Patent Publication Number: US-9903577-B2

Title: LED tube lamp including light strip including a pad and an opening formed on the pad

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a Continuation application of U.S. patent application Ser. No. 15/065,890, filed Mar. 10, 2016, the contents of which are incorporated herein by reference in their entirety, and which is a Continuation-in-part application of U.S. patent application Ser. No. 14/865,387, filed Sep. 25, 2015, the contents of which are incorporated herein by reference in their entirety, and which claims priority under 35 U.S.C. § 119 to the following Chinese Patent Applications Nos.: CN 201510104823.3 filed on 2015 Mar. 10; CN 201510136796.8 filed on 2015 Mar. 27; CN 201510259151.3 filed on 2015 May 19; CN 201510338027.6 filed on 2015 Jun. 17; CN 201510373492.3 filed on 2015 Jun. 26; CN 201510482944.1 filed on 2015 Aug. 7; CN 201510483475.5 filed on 2015 Aug. 8; CN 201510486115.0 filed on 2015 Aug. 8; CN 201510555543.4 filed on 2015 Sep. 2; CN 201510557717.0 filed on 2015 Sep. 6; and CN 201510595173.7 filed on 2015 Sep. 18, the disclosures of each of which are incorporated herein in their entirety by reference. 
     In addition, U.S. patent application Ser. No. 15/065,890 from which this application claims priority as a Continuation application also claims priority under 35 U.S.C. § 119 to the following Chinese Patent Applications Nos.: CN 201510324394.0 filed on 2015 Jun. 12; CN 201510448220.5 filed on 2015 Jul. 27; CN 201510499512.1 filed on 2015 Aug. 14; CN 201510645134.3 filed on 2015 Oct. 8; and CN 201510716899.1 filed on 2015 Oct. 29, the disclosures of each of which are incorporated herein in their entirety by reference. 
    
    
     FIELD OF THE INVENTION 
     The present disclosure relates to an LED tube lamp, and more particularly to an LED tube lamp and its components including anti-flickering circuit. 
     BACKGROUND OF THE INVENTION 
     LED lighting technology is rapidly developing to replace traditional incandescent and fluorescent lightings. LED tube lamps are mercury-free in comparison with fluorescent tube lamps that need to be filled with inert gas and mercury. Thus, it is not surprising that LED tube lamps are becoming a highly-desired illumination option among different available lighting systems used in homes and workplaces, which used to be dominated by traditional lighting options such as compact fluorescent light bulbs (CFLs) and fluorescent tube lamps. Benefits of LED tube lamps include improved durability and longevity and far less energy consumption; therefore, when taking into account all factors, they would typically be considered as a cost-effective lighting option. 
     Typical LED tube lamps have a lamp tube, a circuit board disposed inside the lamp tube with light sources being mounted on the circuit board, and end caps accompanying a power supply provided at two ends of the lamp tube with the electricity from the power supply transmitting to the light sources through the circuit board. 
     The available electronic ballasts are mainly classified into two types of instant start electronic ballast and pre-heat start electronic ballast. The electronic ballast has a resonant circuit, which is designed to match a load characteristic of a fluorescent lamp to provide an appropriate ignition process for igniting the lamp. The load characteristic of the fluorescent lamp is capacitive before the lamp is ignited and is resistive after the lamp is ignited. The LED is a non-linear load, having a completely different load characteristic. Therefore, the LED tube lamp affects the resonant of the resonant circuit and so causes compatible problems. In general, the pre-heat electronic ballast detects the filament of the lamp during ignition process. However, the conventional LED driving circuit can not supply the filament detection and so can not light with the pre-heat electronic ballast. In addition, the electronic ballast is effectively a current source, and it easily results in the problems of over current, over voltage, under current and the under voltage when being used to be a power supply of the LED tube lamp. The LED tube lamp may not provide stable lighting and even the electrical device therein may be damaged. Moreover, a transient flicker appears after the user turned off the power and it makes the user discomfort. 
     Accordingly, the present disclosure and its embodiments are herein provided. 
     SUMMARY OF THE INVENTION 
     It&#39;s specially noted that the present disclosure may actually include one or more inventions claimed currently or not yet claimed, and for avoiding confusion due to unnecessarily distinguishing between those possible inventions at the stage of preparing the specification, the possible plurality of inventions herein may be collectively referred to as “the (present) invention” herein. 
     Various embodiments are summarized in this section, and are described with respect to the “present invention,” which terminology is used to describe certain presently disclosed embodiments, whether claimed or not, and is not necessarily an exhaustive description of all possible embodiments, but rather is merely a summary of certain embodiments. Certain of the embodiments described below as various aspects of the “present invention” can be combined in different manners to form an LED tube lamp or a portion thereof. 
     The present invention provides a novel LED tube lamp, and aspects thereof. 
     In one embodiment, the invention provides an LED tube lamp, comprising a tube, a terminal adapter circuit, a first rectifying circuit, a filtering circuit, an LED lighting module and an anti-flickering circuit. The tube has a first pin and a second pin for receiving an external driving signal. The terminal adapter circuit has two fuses respectively coupled to the first and second pins. The first rectifying circuit is coupled to the first and second pins for rectifying the external driving signal to generate a rectified signal. The filtering circuit is coupled to the first rectifying circuit for filtering the rectified signal to generate a filtered signal. The LED lighting module is coupled to the filtering circuit and the LED lighting module having a LED module, wherein the LED lighting module is configured to receive the filtered signal and generate a driving signal, and the LED module receives the driving signal and lights. The anti-flickering circuit is coupled between the filtering circuit and the LED lighting module, and a current higher than a set anti-flickering current flows the anti-flickering circuit when a peak value of the filtered signal is higher than a minimum conduction voltage of the LED module. 
     The anti-flickering circuit may comprise at least one resistor. 
     The rectifying circuit may be a full-wave rectifying circuit. 
     In one embodiment, the present invention provides an LED tube lamp, further comprising an over voltage protection circuit coupled to a first filtering output terminal and a second output terminal of the filtering circuit to detect the filtered signal for clamping a voltage level of the filtered signal when the voltage level of the filtered signal is higher than a set over voltage value. 
     The over voltage protection circuit may comprise a voltage clamping diode. 
     A frequency of the external driving signal may be in the range of 20 k-50 k Hz. 
     The LED module may comprise at least two LED units, and each LED unit comprises at least two LEDs. 
     The first and second pins may be respectively disposed at two opposite end cap of the LED tube lamp to form a single pin at each end of LED tube lamp. 
     In one embodiment, the present invention provides an LED tube lamp, further comprising a second rectifying circuit coupled to a third pin and a fourth pin for rectifying the external driving signal concurrently with the first rectifying circuit. 
     The first and second pins may be disposed on one end cap of the LED tube lamp and the third and fourth pins are disposed on the other cap end thereof. 
     In one embodiment, the present invention provides an LED tube lamp, further comprising two filament-simulating circuit, wherein one filament-simulating circuit has filament-simulating terminals coupled to the first and second pins, and the other filament-simulating circuit has filament-simulating terminals coupled to the third and fourth pins. 
     In one embodiment, the present invention provides an LED tube lamp, comprising a tube, a first rectifying circuit, a filtering circuit, an LED lighting module, an anti-flickering circuit and an over voltage protection circuit. The tube has a first pin and a second pin for receiving an external driving signal. The first rectifying circuit is coupled to the first and second pins for rectifying the external driving signal to generate a rectified signal. The filtering circuit is coupled to the first rectifying circuit for filtering the rectified signal to generate a filtered signal. The LED lighting module is coupled to the filtering circuit and the LED lighting module having a LED module, wherein the LED lighting module is configured to receive the filtered signal and generate a driving signal, and the LED module receives the driving signal and lights. The anti-flickering circuit is coupled between the filtering circuit and the LED lighting module, and a current higher than a set anti-flickering current flows the anti-flickering circuit when a peak value of the filtered signal is higher than a minimum conduction voltage of the LED module. The over voltage protection circuit is coupled to a first filtering output terminal and a second output terminal of the filtering circuit to detect the filtered signal for clamping a voltage level of the filtered signal when the voltage level of the filtered signal is higher than a set over voltage value. 
     The anti-flickering circuit may comprise at least one resistor. 
     The rectifying circuit may be a full-wave rectifying circuit. 
     The over voltage protection circuit may comprise a voltage clamping diode. 
     A frequency of the external driving signal may be in the range of 20 k-50 k Hz. 
     The LED module may comprise at least two LED units, and each LED unit comprises at least two LEDs. 
     In one embodiment, the present invention provides an LED tube lamp, further comprising a second rectifying circuit coupled to a third pin and a fourth pin for rectifying the external driving signal concurrently with the first rectifying circuit. 
       19 . The LED tube lamp of claim  18 , wherein the first and second pins are disposed on one end cap of the LED tube lamp and the third and fourth pins are disposed on the other cap end thereof. 
     In one embodiment, the present invention provides an LED tube lamp, further comprising two filament-simulating circuit, wherein one filament-simulating circuit has filament-simulating terminals coupled to the first and second pins, and the other filament-simulating circuit has filament-simulating terminals coupled to the third and fourth pins. 
     In one embodiment, the present invention provides an LED tube lamp, further comprising two fuses, wherein one fuse is coupled to the first pin and the other fuse is coupled to the second pin. 
     The first and second pins are respectively disposed at two opposite end cap of the LED tube lamp to form a single pin at each end of LED tube lamp. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view schematically illustrating an LED tube lamp according to one embodiment of the present invention; 
         FIG. 1A  is a perspective view schematically illustrating the different sized end caps of an LED tube lamp according to another embodiment of the present invention to illustrate; 
         FIG. 2  is an exploded view schematically illustrating the LED tube lamp shown in  FIG. 1 ; 
         FIG. 3  is a perspective view schematically illustrating front and top of an end cap of the LED tube lamp according to one embodiment of the present invention; 
         FIG. 4  is a plane cross-sectional view schematically illustrating inside structure of the glass tube of the LED tube lamp according to one embodiment of the present invention, wherein two reflective films are respectively adjacent to two sides of the LED light strip along the circumferential direction of the glass tube; 
         FIG. 5  is a plane cross-sectional view schematically illustrating inside structure of the glass tube of the LED tube lamp according to another embodiment of the present invention, wherein only a reflective film is disposed on one side of the LED light strip along the circumferential direction of the glass tube; 
         FIG. 6  is a plane cross-sectional view schematically illustrating inside structure of the glass tube of the LED tube lamp according to still another embodiment of the present invention, wherein the reflective film is under the LED light strip and extends at both sides along the circumferential direction of the glass tube; 
         FIG. 7  is a plane cross-sectional view schematically illustrating inside structure of the glass tube of the LED tube lamp according to yet another embodiment of the present invention, wherein the reflective film is under the LED light strip and extends at only one side along the circumferential direction of the glass tube; 
         FIG. 8  is a plane cross-sectional view schematically illustrating inside structure of the glass tube of the LED tube lamp according to still yet another embodiment of the present invention, wherein two reflective films are respectively adjacent to two sides of the LED light strip and extending along the circumferential direction of the glass tube; 
         FIG. 9  is a plane sectional view schematically illustrating the LED light strip is a bendable circuit sheet with ends thereof passing across the glass tube of the LED tube lamp to soldering bonded to the output terminals of the power supply according to one embodiment of the present invention; 
         FIG. 10  is a plane cross-sectional view schematically illustrating a bi-layered structure of the bendable circuit sheet of the LED light strip of the LED tube lamp according to an embodiment of the present invention; 
         FIG. 11  is a perspective view schematically illustrating the soldering pad of the bendable circuit sheet of the LED light strip for soldering connection with the printed circuit board of the power supply of the LED tube lamp according to one embodiment of the present invention; 
         FIG. 12  is a plane view schematically illustrating the arrangement of the soldering pads of the bendable circuit sheet of the LED light strip of the LED tube lamp according to one embodiment of the present invention; 
         FIG. 13  is a plane view schematically illustrating a row of three soldering pads of the bendable circuit sheet of the LED light strip of the LED tube lamp according to another embodiment of the present invention; 
         FIG. 14  is a plane view schematically illustrating two rows of soldering pads of the bendable circuit sheet of the LED light strip of the LED tube lamp according to still another embodiment of the present invention; 
         FIG. 15  is a plane view schematically illustrating a row of four soldering pads of the bendable circuit sheet of the LED light strip of the LED tube lamp according to yet another embodiment of the present invention; 
         FIG. 16  is a plane view schematically illustrating two rows of two soldering pads of the bendable circuit sheet of the LED light strip of the LED tube lamp according to yet still another embodiment of the present invention; 
         FIG. 17  is a plane view schematically illustrating through holes are formed on the soldering pads of the bendable circuit sheet of the LED light strip of the LED tube lamp according to one embodiment of the present invention; 
         FIG. 18  is a plane cross-sectional view schematically illustrating soldering bonding process utilizing the soldering pads of the bendable circuit sheet of the LED light strip of  FIG. 17  taken from side view and the printed circuit board of the power supply according to one embodiment of the present invention; 
         FIG. 19  is a plane cross-sectional view schematically illustrating soldering bonding process utilizing the soldering pads of the bendable circuit sheet of the LED light strip of  FIG. 17  taken from side view and the printed circuit board of the power supply according to another embodiment of the present invention, wherein the through hole of the soldering pads is near the edge of the bendable circuit sheet; 
         FIG. 20  is a plane view schematically illustrating notches formed on the soldering pads of the bendable circuit sheet of the LED light strip of the LED tube lamp according to one embodiment of the present invention; 
         FIG. 21  is a plane cross-sectional view of  FIG. 20  taken along a line A-A′; 
         FIG. 22  is a perspective view schematically illustrating a circuit board assembly composed of the bendable circuit sheet of the LED light strip and the printed circuit board of the power supply according to another embodiment of the present invention; 
         FIG. 23  is a perspective view schematically illustrating another arrangement of the circuit board assembly of  FIG. 22 ; 
         FIG. 24  is a perspective view schematically illustrating an LED lead frame for the LED light sources of the LED tube lamp according to one embodiment of the present invention; 
         FIG. 25  is a perspective view schematically illustrating a power supply of the LED tube lamp according to one embodiment of the present invention; 
         FIGS. 28A to 28F  are views schematically illustrating various end caps having safety switch according to embodiments of the present invention; and 
         FIG. 27  is a plane view schematically illustrating a LED tube lamp with end caps having safety switch according to one embodiment of the present invention; 
         FIG. 28A  is a block diagram of an exemplary power supply module  250  in an LED tube lamp according to some embodiments of the present invention; 
         FIG. 28B  is a block diagram of an exemplary power supply module  250  in an LED tube lamp according to some embodiments of the present invention; 
         FIG. 28C  is a block diagram of an exemplary LED lamp according to some embodiments of the present invention; 
         FIG. 28D  is a block diagram of an exemplary power supply module  250  in an LED tube lamp according to some embodiments of the present invention; 
         FIG. 28E  is a block diagram of an LED lamp according to some embodiments of the present invention; 
         FIG. 29A  is a schematic diagram of a rectifying circuit according to some embodiments of the present invention; 
         FIG. 29B  is a schematic diagram of a rectifying circuit according to some embodiments of the present invention; 
         FIG. 29C  is a schematic diagram of a rectifying circuit according to some embodiments of the present invention; 
         FIG. 29D  is a schematic diagram of a rectifying circuit according to some embodiments of the present invention; 
         FIG. 30A  is a schematic diagram of a terminal adapter circuit according to some embodiments of the present invention; 
         FIG. 30B  is a schematic diagram of a terminal adapter circuit according to some embodiments of the present invention; 
         FIG. 30C  is a schematic diagram of a terminal adapter circuit according to some embodiments of the present invention; 
         FIG. 30D  is a schematic diagram of a terminal adapter circuit according to some embodiments of the present invention; 
         FIG. 31A  is a schematic diagram of an LED module according to some embodiments of the present invention; 
         FIG. 31B  is a schematic diagram of an LED module according to some embodiments of the present invention; 
         FIG. 31C  is a plan view of a circuit layout of the LED module according to some embodiments of the present invention; 
         FIG. 31D  is a plan view of a circuit layout of the LED module according to some embodiments of the present invention; 
         FIG. 31E  is a plan view of a circuit layout of the LED module according to some embodiments of the present invention; 
         FIG. 32A  is a block diagram of an exemplary power supply module in an LED lamp according to some embodiments of the present invention; 
         FIG. 32B  is a schematic diagram of an anti-flickering circuit according to some embodiments of the present invention; 
         FIG. 33A  is a block diagram of an exemplary power supply module in an LED tube lamp according to some embodiments of the present invention; 
         FIG. 33B  is a schematic diagram of a filament-simulating circuit according to some embodiments of the present invention; 
         FIG. 33C  is a schematic block diagram including a filament-simulating circuit according to some embodiments of the present invention; 
         FIG. 33D  is a schematic block diagram including a filament-simulating circuit according to some embodiments of the present invention; 
         FIG. 33E  is a schematic diagram of a filament-simulating circuit according to some embodiments of the present invention; 
         FIG. 33F  is a schematic block diagram including a filament-simulating circuit according to some embodiments of the present invention; 
         FIG. 34A  is a block diagram of an exemplary power supply module in an LED tube lamp according to some embodiments of the present invention; and 
         FIG. 34B  is a schematic diagram of an OVP circuit according to an embodiment of the present invention. 
         FIG. 35A  is a block diagram of an exemplary power supply module in an LED lamp according to some embodiments of the present invention; 
         FIG. 35B  is a block diagram of an exemplary power supply module in an LED lamp according to some embodiments of the present invention; 
         FIG. 35C  illustrates an arrangement with a ballast-compatible circuit in an LED lamp according to some embodiments of the present invention; 
         FIG. 35D  is a block diagram of an exemplary power supply module in an LED lamp according to some embodiments of the present invention; 
         FIG. 35E  is a block diagram of an exemplary power supply module in an LED lamp according to some embodiments of the present invention; 
         FIG. 35F  is a schematic diagram of a ballast-compatible circuit according to some embodiments of the present invention; 
         FIG. 35G  is a block diagram of an exemplary power supply module in an LED lamp according to some embodiments of the present invention; 
         FIG. 35H  is a schematic diagram of a ballast-compatible circuit according to some embodiments of the present invention; 
         FIG. 35I  illustrates a ballast-compatible circuit according to some embodiments of the present invention; 
         FIG. 36A  is a block diagram of an exemplary power supply module in an LED tube lamp according to some embodiments of the present invention; 
         FIG. 36B  is a block diagram of an exemplary power supply module in an LED tube lamp according to some embodiments of the present invention; 
         FIG. 36C  is a block diagram of a ballast detection circuit according to some embodiments of the present invention; 
         FIG. 36D  is a schematic diagram of a ballast detection circuit according to some embodiments of the present invention; 
         FIG. 36E  is a schematic diagram of a ballast detection circuit according to some embodiments of the present invention; 
         FIG. 37A  is a block diagram of a filtering circuit according to some embodiments of the present invention; 
         FIG. 37B  is a schematic diagram of a filtering unit according to some embodiments of the present invention; 
         FIG. 37C  is a schematic diagram of a filtering unit according to some embodiments of the present invention; 
         FIG. 37D  is a schematic diagram of a filtering unit according to some embodiments of the present invention; and 
         FIG. 37E  is a schematic diagram of a filtering unit according to some embodiments of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     The present disclosure provides a novel LED tube lamp based on the glass made tube to solve the abovementioned problems. The present disclosure will now be described in the following embodiments with reference to the drawings. The following descriptions of various embodiments of this invention are presented herein for purpose of illustration and giving examples only. It is not intended to be exhaustive or to be limited to the precise form disclosed. These example embodiments are just that—examples—and many implementations and variations are possible that do not require the details provided herein. It should also be emphasized that the disclosure provides details of alternative examples, but such listing of alternatives is not exhaustive. Furthermore, any consistency of detail between various examples should not be interpreted as requiring such detail—it is impracticable to list every possible variation for every feature described herein. The language of the claims should be referenced in determining the requirements of the invention. 
     Referring to  FIGS. 1 and 2 , an LED tube lamp of one embodiment of the present invention includes a glass tube  1 , an LED light strip  2  disposed inside the glass tube  1 , and two end caps  3  respectively disposed at two ends of the glass tube  1 . The sizes of the two end caps  3  may be same or different. Referring to  FIG. 1A , the size of one end cap may in some embodiments be about 30% to about 80% times the size of the other end cap. In one embodiment, the end cap is wholly made of a plastic material, and preferably, the end cap is made by integral molding. In one embodiment, the end caps are made of a transparent plastic material and/or a thermal conductive plastic material. 
     Furthermore, the glass tube and the end cap are secured by a highly thermal conductive silicone gel with a thermal conductivity not less than 0.7 w/m·k. Preferably, the thermal conductivity of the highly thermal conductive silicone gel is not less than 2 w/m·k. In one embodiment, the highly thermal conducive silicone gel is of high viscosity, and the end cap and the end of the glass tube could be secured by using the highly thermal conductive silicone gel and therefore qualified in a torque test of 1.5 to 5 newton-meters (Nt-m) and/or in a bending test of 5 to 10 newton-meters (Nt-m). 
     In one embodiment, the glass tube could be covered by a heat shrink sleeve (not shown) to make the glass tube electrically insulated. The thickness range of the heat shrink sleeve may be 20 μm-200 μm, and preferably be 50 μm-100 μm. 
     In some embodiments, the inner surface of the glass tube could be formed with a rough surface while the outer surface of the glass tube remains glossy. In other words, the inner surface is rougher than the outer surface. The roughness Ra of the inner surface is from 0.1 to 40 μm, and preferably, from 1 to 20 μm. 
     Controlled roughness of the surface is obtained mechanically by a cutter grinding against a workpiece, deformation on a surface of a workpiece being cut off or high frequency vibration in the manufacturing system. Alternatively, roughness is obtained chemically by etching a surface. Depending on the luminous effect the glass tube is designed to produce, a suitable combination of amplitude and frequency of a roughened surface is provided by a matching combination of workpiece and finishing technique. 
     The LED tube lamp is configured to reduce internal reflectance by applying a layer of anti-reflection coating to an inner surface of the glass tube. The coating has an upper boundary, which divides the inner surface of the glass tube and the anti-reflection coating, and a lower boundary, which divides the anti-reflection coating and the air in the glass tube. Light waves reflected by the upper and lower boundaries of the coating interfere with one another to reduce reflectance. The coating is made from a material with a refractive index of a square root of the refractive index of the glass tube by vacuum deposition. Tolerance of the refractive index is ±20%. The thickness of the coating is chosen to produce destructive interference in the light reflected from the interfaces and constructive interference in the corresponding transmitted light. In an improved embodiment, reflectance is further reduced by using alternating layers of a low-index coating and a higher-index coating. The multi-layer structure is designed to, when setting parameters such as combination and permutation of layers, thickness of a layer, refractive index of the material, give low reflectivity over a broad band that covers at least 60%, or preferably, 80% of the wavelength range beaming from the LED light source  202 . In some embodiments, three successive layers of anti-reflection coatings are applied to an inner surface of the glass tube  1  to obtain low reflectivity over a wide range of frequencies. The thicknesses of the coatings are chosen to give the coatings optical depths of, respectively, one half, and one quarter of the wavelength range coming from the LED light source  202 . Dimensional tolerance for the thickness of the coating is set at ±20%. 
     In some embodiments, the terminal part of the glass tube to be in touch with the end cap includes a protrusion region which could be formed to rise inwardly or outwardly. Furthermore, the outer surface of the protrusion region is rougher than the outer surface of the glass tube. These protrusion regions help to contribute larger contact surface areas for the adhesives between the glass tube and the end caps such that the connection between the end caps and the glass tube become more secure. 
     Referring to  FIGS. 2, and 3 , in one embodiment, the end cap  3  may have openings  304  to dissipate heat generated by the power supply modules inside the end cap  3  so as to prevent a high temperature condition inside the end cap  3  that might reduce reliability. In some embodiments, the openings are in a shape of arc; especially in shape of three arcs with different size. In one embodiment, the openings are in a shape of three arcs with gradually varying size. The openings on the end cap  3  can be in any one of the above-mentioned shape or any combination thereof. 
     In other embodiments, the end cap  3  is provided with a socket (not shown) for installing the power supply module. 
     Referring to  FIG. 4 , in one embodiment, the glass tube  1  further has a diffusion film  13  coated and bonded to the inner wall thereof so that the light outputted or emitted from the LED light sources  202  is diffused by the diffusion film  13  and then pass through the glass tube  1 . The diffusion film  13  can be in form of various types, such as a coating onto the inner wall or outer wall of the glass tube  1 , or a diffusion coating layer (not shown) coated at the surface of each LED light source  202 , or a separate membrane covering the LED light source  202 . 
     Referring again to  FIG. 4 , when the diffusion film  13  is in form of a sheet, it covers but not in contact with the LED light sources  202 . The diffusion film  13  in form of a sheet is usually called an optical diffusion sheet or board, usually a composite made of mixing diffusion particles into polystyrene (PS), polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), and/or polycarbonate (PC), and/or any combination thereof. The light passing through such composite is diffused to expand in a wide range of space such as a light emitted from a plane source, and therefore makes the brightness of the LED tube lamp uniform. 
     In alternative embodiment, the diffusion film  13  is in form of an optical diffusion coating, which is composed of any one of calcium carbonate, halogen calcium phosphate and aluminum oxide, or any combination thereof. When the optical diffusion coating is made from a calcium carbonate with suitable solution, an excellent light diffusion effect and transmittance to exceed 90% can be obtained. 
     In the embodiment, the composition of the diffusion film  13  in form of the optical diffusion coating includes calcium carbonate, strontium phosphate (e.g., CMS-5000, white powder), thickener, and a ceramic activated carbon (e.g., ceramic activated carbon SW-C, which is a colorless liquid). Specifically, such an optical diffusion coating on the inner circumferential surface of the glass tube has an average thickness ranging between about 20 to about 30 μm. A light transmittance of the diffusion film  13  using this optical diffusion coating is about 90%. Generally speaking, the light transmittance of the diffusion film  13  ranges from 85% to 96%. In addition, this diffusion film  13  can also provide electrical isolation for reducing risk of electric shock to a user upon breakage of the glass tube  1 . Furthermore, the diffusion film  13  provides an improved illumination distribution uniformity of the light outputted by the LED light sources  202  such that the light can illuminate the back of the light sources  202  and the side edges of the bendable circuit sheet so as to avoid the formation of dark regions inside the glass tube  1  and improve the illumination comfort. In another possible embodiment, the light transmittance of the diffusion film can be 92% to 94% while the thickness ranges from about 200 to about 300 μm. 
     In another embodiment, the optical diffusion coating can also be made of a mixture including calcium carbonate-based substance, some reflective substances like strontium phosphate or barium sulfate, a thickening agent, ceramic activated carbon, and deionized water. The mixture is coated on the inner circumferential surface of the glass tube and has an average thickness ranging between about 20 to about 30 μm. In view of the diffusion phenomena in microscopic terms, light is reflected by particles. The particle size of the reflective substance such as strontium phosphate or barium sulfate will be much larger than the particle size of the calcium carbonate. Therefore, adding a small amount of reflective substance in the optical diffusion coating can effectively increase the diffusion effect of light. 
     In other embodiments, halogen calcium phosphate or aluminum oxide can also serve as the main material for forming the diffusion film  13 . The particle size of the calcium carbonate is about 2 to 4 μm, while the particle size of the halogen calcium phosphate and aluminum oxide are about 4 to 6 μm and 1 to 2 μm, respectively. When the light transmittance is required to be 85% to 92%, the required average thickness for the optical diffusion coating mainly having the calcium carbonate is about 20 to about 30 μm, while the required average thickness for the optical diffusion coating mainly having the halogen calcium phosphate may be about 25 to about 35 μm, the required average thickness for the optical diffusion coating mainly having the aluminum oxide may be about 10 to about 15 μm. However, when the required light transmittance is up to 92% and even higher, the optical diffusion coating mainly having the calcium carbonate, the halogen calcium phosphate, or the aluminum oxide must be thinner. 
     The main material and the corresponding thickness of the optical diffusion coating can be decided according to the place for which the glass tube  1  is used and the light transmittance required. It is to be noted that the higher the light transmittance of the diffusion film is required, the more apparent the grainy visual of the light sources is. 
     Referring to  FIG. 4 , the inner circumferential surface of the glass tube  1  may also be provided or bonded with a reflective film  12 . The reflective film  12  is provided around the LED light sources  202 , and occupies a portion of an area of the inner circumferential surface of the glass tube  1  arranged along the circumferential direction thereof. As shown in  FIG. 4 , the reflective film  12  is disposed at two sides of the LED light strip  2  extending along a circumferential direction of the glass tube  1 . The LED light strip  2  is basically in a middle position of the glass tube  1  and between the two reflective films  12 . The reflective film  12 , when viewed by a person looking at the glass tube from the side (in the X-direction shown in  FIG. 4 ), serves to block the LED light sources  202 , so that the person does not directly see the LED light sources  202 , thereby reducing the visual graininess effect. On the other hand, that the lights emitted from the LED light sources  202  are reflected by the reflective film  12  facilitates the divergence angle control of the LED tube lamp, so that more lights illuminate toward directions without the reflective film  12 , such that the LED tube lamp has higher energy efficiency when providing the same level of illumination performance. 
     Specifically, the reflection film  12  is provided on the inner peripheral surface of the glass tube  1 , and has an opening  12   a  configured to accommodate the LED light strip  2 . The size of the opening  12   a  is the same or slightly larger than the size of the LED light strip  2 . During assembly, the LED light sources  202  are mounted on the LED light strip  2  (a bendable circuit sheet) provided on the inner surface of the glass tube  1 , and then the reflective film  12  is adhered to the inner surface of the glass tube  1 , so that the opening  12   a  of the reflective film  12  correspondingly matches the LED light strip  2  in a one-to-one relationship, and the LED light strip  2  is exposed to the outside of the reflective film  12 . 
     In one embodiment, the reflectance of the reflective film  12  is generally at least greater than 85%, in some embodiments greater than 90%, and in some embodiments greater than 95%, to be most effective. In one embodiment, the reflective film  12  extends circumferentially along the length of the glass tube  1  occupying about 30% to 50% of the inner surface area of the glass tube  1 . In other words, a ratio of a circumferential length of the reflective film  12  along the inner circumferential surface of the glass tube  1  to a circumferential length of the glass tube  1  is about 0.3 to 0.5. In the illustrated embodiment of  FIG. 4 , the reflective film  12  is disposed substantially in the middle along a circumferential direction of the glass tube  1 , so that the two distinct portions or sections of the reflective film  12  disposed on the two sides of the LED light strip  2  are substantially equal in area. The reflective film  12  may be made of PET with some reflective materials such as strontium phosphate or barium sulfate or any combination thereof, with a thickness between about 140 μm and about 350 μm or between about 150 μm and about 220 μm for a more preferred effect in some embodiments. As shown in  FIG. 5 , in other embodiments, the reflective film  12  may be provided along the circumferential direction of the glass tube  1  on only side of the LED light strip  2  occupying the same percentage of the inner surface area of the glass tube  1  (e.g., 15% to 25% for the one side). Alternatively, as shown in  FIGS. 6 and 7 , the reflective film  12  may be provided without any opening, and the reflective film  12  is directly adhered or mounted to the inner surface of the glass tube  1  and followed by mounting or fixing the LED light strip  2  on the reflective film  12  such that the reflective film  12  positioned on one side or two sides of the LED light strip  2 . 
     In the above-mentioned embodiments, various types of the reflective film  12  and the diffusion film  13  can be adopted to accomplish optical effects including single reflection, single diffusion, and/or combined reflection-diffusion. For example, the glass tube  1  may be provided with only the reflective film  12 , and no diffusion film  13  is disposed inside the glass tube  1 , such as shown in  FIGS. 6, 7, and 8 . 
     In other embodiments, the width of the LED light strip  2  (along the circumferential direction of the glass tube) can be widened to occupy a circumference area of the inner circumferential surface of the glass tube  1 . Since the LED light strip  2  has on its surface a circuit protective layer made of an ink which can reflect lights, the widen part of the LED light strip  2  functions like the reflective film  12  as mentioned above. In some embodiments, a ratio of the length of the LED light strip  2  along the circumferential direction to the circumferential length of the glass tube  1  is about 0.2 to 0.5. The light emitted from the light sources could be concentrated by the reflection of the widen part of the LED light strip  2 . 
     In other embodiments, the inner surface of the glass made glass tube may be coated totally with the optical diffusion coating, or partially with the optical diffusion coating (where the reflective film  12  is coated have no optical diffusion coating). No matter in what coating manner, it is better that the optical diffusion coating be coated on the outer surface of the rear end region of the glass tube  1  so as to firmly secure the end cap  3  with the glass tube  1 . 
     In the present invention, the light emitted from the light sources may be processed with the abovementioned diffusion film, reflective film, other kind of diffusion layer sheet, adhesive film, or any combination thereof. 
     Referring again to  FIG. 2 , the LED tube lamp according to the embodiment of present invention also includes an adhesive sheet  4 , an insulation adhesive sheet  7 , and an optical adhesive sheet  8 . The LED light strip  2  is fixed by the adhesive sheet  4  to an inner circumferential surface of the glass tube  1 . The adhesive sheet  4  may be but not limited to a silicone adhesive. The adhesive sheet  4  may be in form of several short pieces or a long piece. Various kinds of the adhesive sheet  4 , the insulation adhesive sheet  7 , and the optical adhesive sheet  8  can be combined to constitute various embodiments of the present invention. 
     The insulation adhesive sheet  7  is coated on the surface of the LED light strip  2  that faces the LED light sources  202  so that the LED light strip  2  is not exposed and thus electrically insulated from the outside environment. In application of the insulation adhesive sheet  7 , a plurality of through holes  71  on the insulation adhesive sheet  7  are reserved to correspondingly accommodate the LED light sources  202  such that the LED light sources  202  are mounted in the through holes  71 . The material composition of the insulation adhesive sheet  7  includes vinyl silicone, hydrogen polysiloxane and aluminum oxide. The insulation adhesive sheet  7  has a thickness ranging from about 100 μm to about 140 μm (micrometers). The insulation adhesive sheet  7  having a thickness less than 100 μm typically does not produce sufficient insulating effect, while the insulation adhesive sheet  7  having a thickness more than 140 μm may result in material waste. 
     The optical adhesive sheet  8 , which is a clear or transparent material, is applied or coated on the surface of the LED light source  202  in order to ensure optimal light transmittance. After being applied to the LED light sources  202 , the optical adhesive sheet  8  may have a granular, strip-like or sheet-like shape. The performance of the optical adhesive sheet  8  depends on its refractive index and thickness. The refractive index of the optical adhesive sheet  8  is in some embodiments between 1.22 and 1.6. In some embodiments, it is better for the optical adhesive sheet  8  to have a refractive index being a square root of the refractive index of the housing or casing of the LED light source  202 , or the square root of the refractive index of the housing or casing of the LED light source  202  plus or minus 15%, to contribute better light transmittance. The housing/casing of the LED light sources  202  is a structure to accommodate and carry the LED dies (or chips) such as a LED lead frame  202   b  as shown in  FIG. 24 . The refractive index of the optical adhesive sheet  8  may range from 1.225 to 1.253. In some embodiments, the thickness of the optical adhesive sheet  8  may range from 1.1 mm to 1.3 mm. The optical adhesive sheet  8  having a thickness less than 1.1 mm may not be able to cover the LED light sources  202 , while the optical adhesive sheet  8  having a thickness more than 1.3 mm may reduce light transmittance and increases material cost. 
     In process of assembling the LED light sources to the LED light strip, the optical adhesive sheet  8  is firstly applied on the LED light sources  202 ; then the insulation adhesive sheet  7  is coated on one side of the LED light strip  2 ; then the LED light sources  202  are fixed or mounted on the LED light strip  2 ; the other side of the LED light strip  2  being opposite to the side of mounting the LED light sources  202  is bonded and affixed to the inner surface of the glass tube  1  by the adhesive sheet  4 ; finally, the end cap  3  is fixed to the end portion of the glass tube  1 , and the LED light sources  202  and the power supply  5  are electrically connected by the LED light strip  2 . As shown in  FIG. 9 , the bendable circuit sheet  2  has a freely extending portion  21  to be soldered or traditionally wire-bonded with the power supply  5  to form a complete LED tube lamp. 
     In this embodiment, the LED light strip  2  is fixed by the adhesive sheet  4  to an inner circumferential surface of the glass tube  1 , so as to increase the light illumination angle of the LED tube lamp and broaden the viewing angle to be greater than 330 degrees. By means of applying the insulation adhesive sheet  7  and the optical adhesive sheet  8 , electrical insulation of the entire light strip  2  is accomplished such that electrical shock would not occur even when the glass tube  1  is broken and therefore safety could be improved. 
     Furthermore, the inner peripheral surface or the outer circumferential surface of the glass made glass tube  1  may be covered or coated with an adhesive film (not shown) to isolate the inside from the outside of the glass made glass tube  1  when the glass made glass tube  1  is broken. In this embodiment, the adhesive film is coated on the inner peripheral surface of the glass tube  1 . The material for the coated adhesive film includes methyl vinyl silicone oil, hydro silicone oil, xylene, and calcium carbonate, wherein xylene is used as an auxiliary material. The xylene will be volatilized and removed when the coated adhesive film on the inner surface of the glass tube  1  solidifies or hardens. The xylene is mainly used to adjust the capability of adhesion and therefore to control the thickness of the coated adhesive film. 
     In one embodiment, the thickness of the coated adhesive film is in some embodiments between about 100 and about 140 micrometers (μm). The adhesive film having a thickness being less than 100 micrometers may not have sufficient shatterproof capability for the glass tube, and the glass tube is thus prone to crack or shatter. The adhesive film having a thickness being larger than 140 micrometers may reduce the light transmittance and also increases material cost. The thickness of the coated adhesive film may be between about 10 and about 800 micrometers (μm) when the shatterproof capability and the light transmittance are not strictly demanded. 
     In this embodiment, the inner peripheral surface or the outer circumferential surface of the glass made glass tube  1  is coated with an adhesive film such that the broken pieces are adhered to the adhesive film when the glass made glass tube is broken. Therefore, the glass tube  1  would not be penetrated to form a through hole connecting the inside and outside of the glass tube  1  and thus prevents a user from touching any charged object inside the glass tube  1  to avoid electrical shock. In addition, the adhesive film is able to diffuse light and allows the light to transmit such that the light uniformity and the light transmittance of the entire LED tube lamp increases. The adhesive film can be used in combination with the adhesive sheet  4 , the insulation adhesive sheet  7  and the optical adhesive sheet  8  to constitute various embodiments of the present invention. As the LED light strip  2  is configured to be a bendable circuit sheet, no coated adhesive film is thereby required. 
     In certain embodiments, a bendable circuit sheet is adopted as the LED light strip  2  for that such a LED light strip  2  would not allow a ruptured or broken glass tube to maintain a straight shape and therefore instantly inform the user of the disability of the LED tube lamp and avoid possibly incurred electrical shock. 
     Referring to  FIG. 10 , in one embodiment, the LED light strip  2  includes a bendable circuit sheet having a metal layer  2   a  and a dielectric layer  2   b  that are arranged in a stacked manner, wherein the metal layer  2   a  is electrically conductive and may be a patterned wiring layer. The metal layer  2   a  and the dielectric layer  2   b  may have same areas. The LED light source  202  is disposed on one surface of the metal layer  2   a , the dielectric layer  2   b  is disposed on the other surface of the metal layer  2   a  that is away from the LED light sources  202 . The metal layer  2   a  is electrically connected to the power supply  5  to carry direct current (DC) signals. Meanwhile, the surface of the dielectric layer  2   b  away from the metal layer  2   a  is fixed to the inner circumferential surface of the glass tube  1  by means of the adhesive sheet  4 . In other words, the LED light strip  2  may have a bendable circuit sheet being made of only the single metal layer  2   a  or a two-layered structure having the metal layer  2   a  and the dielectric layer  2   b . In this case, the structure of the bendable circuit sheet can be thinned and the metal layer originally attached to the tube wall of the glass tube can be removed. Even more, only the single metal layer  2   a  for power wiring is kept. Therefore, the LED light source utilization efficiency is improved. This is quite different from the typical flexible circuit board having a three-layered structure (one dielectric layer sandwiched with two metal layers). The bendable circuit sheet is accordingly more bendable or flexible to curl when compared with the conventional three-layered flexible substrate. As a result, the bendable circuit sheet of the LED light strip  2  can be installed in a glass tube with a customized shape or non-tubular shape, and fitly mounted to the inner surface of the glass tube. 
     In another embodiment, the outer surface of the metal layer  2   a  or the dielectric layer  2   b  may be covered with a circuit protective layer made of an ink with function of resisting soldering and increasing reflectivity. Alternatively, the dielectric layer can be omitted and the metal layer can be directly bonded to the inner circumferential surface of the glass tube, and the outer surface of the metal layer  2   a  is coated with the circuit protective layer. No matter the bendable circuit sheet is one-layered structure made of just single metal layer  2   a , or a two-layered structure made of one single metal layer  2   a  and one dielectric layer  2   b , the circuit protective layer can be adopted. The circuit protective layer can be disposed only on one side/surface of the LED light strip  2 , such as the surface having the LED light source  202 . The bendable circuit sheet closely mounted to the inner surface of the glass tube is preferable in some cases. In addition, using fewer layers of the bendable circuit sheet improves the heat dissipation and lowers the material cost. 
     Moreover, the length of the bendable circuit sheet could be greater than the length of the glass tube. 
     In other embodiments, the LED light strip may be replaced by a hard substrate such as an aluminum substrate, a ceramic substrate or a fiberglass substrate having two-layered structure. 
     Referring to  FIG. 2 , in one embodiment, the LED light strip  2  has a plurality of LED light sources  202  mounted thereon, and the end cap  3  has a power supply  5  installed therein. The LED light sources  202  and the power supply  5  are electrically connected by the LED light strip  2 . The power supply  5  may be a single integrated unit (i.e., all of the power supply components are integrated into one module unit) installed in one end cap  3 . Alternatively, the power supply  5  may be divided into two separate units (i.e. all of the power supply components are divided into two parts) installed in two end caps  3 , respectively. 
     The power supply  5  can be fabricated by various ways. For example, the power supply  5  may be an encapsulation body formed by injection molding a silicone gel with high thermal conductivity such as being greater than 0.7 w/m·k. This kind of power supply has advantages of high electrical insulation, high heat dissipation, and regular shape to match other components in an assembly. Alternatively, the power supply  5  in the end caps may be a printed circuit board having components that are directly exposed or packaged by a conventional heat shrink sleeve. The power supply  5  according to some embodiments of the present invention can be a single printed circuit board provided with a power supply module as shown in  FIG. 9  or a single integrated unit as shown in  FIG. 25 . 
     Referring to  FIGS. 2 and 25 , in one embodiment of the present invention, the power supply  5  is provided with a male plug  51  at one end and a metal pin  52  at the other end, one end of the LED light strip  2  is correspondingly provided with a female plug  201 , and the end cap  3  is provided with a hollow conductive pin  301  to be connected with an outer electrical power source. Specifically, the male plug  51  is fittingly inserted into the female plug  201  of the LED light strip  2 , while the metal pins  52  are fittingly inserted into the hollow conductive pins  301  of the end cap  3 . The male plug  51  and the female plug  201  function as a connector between the power supply  5  and the LED light strip  2 . Upon insertion of the metal pin  502 , the hollow conductive pin  301  is punched with an external punching tool to slightly deform such that the metal pin  502  of the power supply  5  is secured and electrically connected to the hollow conductive pin  301 . Upon turning on the electrical power, the electrical current passes in sequence through the hollow conductive pin  301 , the metal pin  52 , the male plug  51 , and the female plug  201  to reach the LED light strip  2  and go to the LED light sources  202 . However, the power supply  5  of the present invention is not limited to the modular type as shown in  FIG. 25 . The power supply  5  may be a printed circuit board provided with a power supply module and electrically connected to the LED light strip  2  via the abovementioned the male plug  51  and female plug  52  combination. In another embodiment, the power supply and the LED light strip may connect to each other by providing at the end of the power supply with a female plug and at the end of the LED light strip with a male plug. The hollow conductive pin  301  may be one or two in number. 
     In another embodiment, a traditional wire bonding technique can be used instead of the male plug  51  and the female plug  52  for connecting any kind of the power supply  5  and the light strip  2 . Furthermore, the wires may be wrapped with an electrically insulating tube to protect a user from being electrically shocked. However, the bonded wires tend to be easily broken during transportation and can therefore cause quality issues. 
     In still another embodiment, the connection between the power supply  5  and the LED light strip  2  may be accomplished via tin soldering, rivet bonding, or welding. One way to secure the LED light strip  2  is to provide the adhesive sheet  4  at one side thereof and adhere the LED light strip  2  to the inner surface of the glass tube  1  via the adhesive sheet  4 . Two ends of the LED light strip  2  can be either fixed to or detached from the inner surface of the glass tube  1 . 
     In case that two ends of the LED light strip  2  are fixed to the inner surface of the glass tube  1 , it may be preferable that the bendable circuit sheet of the LED light strip  2  is provided with the female plug  201  and the power supply is provided with the male plug  51  to accomplish the connection between the LED light strip  2  and the power supply  5 . In this case, the male plug  51  of the power supply  5  is inserted into the female plug  201  to establish electrically conductive. 
     In case that two ends of the LED light strip  2  are detached from the inner surface of the glass tube and that the LED light strip  2  is connected to the power supply  5  via wire-bonding, any movement in subsequent transportation is likely to cause the bonded wires to break. Therefore, a preferable option for the connection between the light strip  2  and the power supply  5  could be soldering. Specifically, referring to  FIG. 9 , the ends of the LED light strip  2  including the bendable circuit sheet are arranged to pass over and directly soldering bonded to an output terminal of the power supply  5  such that the product quality is improved without using wires. In this way, the female plug  201  and the male plug  51  respectively provided for the LED light strip  2  and the power supply  5  are no longer needed. 
     Referring to  FIG. 11 , an output terminal of the printed circuit board of the power supply  5  may have soldering pads “a” provided with an amount of tin solder with a thickness sufficient to later form a solder joint. Correspondingly, the ends of the LED light strip  2  may have soldering pads “b”. The soldering pads “a” on the output terminal of the printed circuit board of the power supply  5  are soldered to the soldering pads “b” on the LED light strip  2  via the tin solder on the soldering pads “a”. The soldering pads “a” and the soldering pads “b” may be face to face during soldering such that the connection between the LED light strip  2  and the printed circuit board of the power supply  5  is the most firm. However, this kind of soldering requires that a thermo-compression head presses on the rear surface of the LED light strip  2  and heats the tine solder, i.e. the LED light strip  2  intervenes between the thermo-compression head and the tin solder, and therefor is easily to cause reliability problems. Referring to  FIG. 17 , a through hole may be formed in each of the soldering pads “b” on the LED light strip  2  to allow the soldering pads “b” overlay the soldering pads “b” without face-to-face and the thermo-compression head directly presses tin solders on the soldering pads “a” on surface of the printed circuit board of the power supply  5  when the soldering pads “a” and the soldering pads “b” are vertically aligned. This is an easy way to accomplish in practice. 
     Referring again to  FIG. 11 , two ends of the LED light strip  2  detached from the inner surface of the glass tube  1  are formed as freely extending portions  21 , while most of the LED light strip  2  is attached and secured to the inner surface of the glass tube  1 . One of the freely extending portions  21  has the soldering pads “b” as mentioned above. Upon assembling of the LED tube lamp, the freely extending end portions  21  along with the soldered connection of the printed circuit board of the power supply  5  and the LED light strip  2  would be coiled, curled up or deformed to be fittingly accommodated inside the glass tube  1 . In this embodiment, during the connection of the LED light strip  2  and the power supply  5 , the soldering pads “b” and the soldering pads “a” and the LED light sources  202  are on surfaces facing toward the same direction and the soldering pads “b” on the LED light strip  2  are each formed with a through hole “e” as shown in  FIG. 17  such that the soldering pads “b” and the soldering pads “a” communicate with each other via the through holes “e”. When the freely extending end portions  21  are deformed due to contraction or curling up, the soldered connection of the printed circuit board of the power supply  5  and the LED light strip  2  exerts a lateral tension on the power supply  5 . Furthermore, the soldered connection of the printed circuit board of the power supply  5  and the LED light strip  2  also exerts a downward tension on the power supply  5  when compared with the situation where the soldering pads “a” of the power supply  5  and the soldering pads “b” of the LED light strip  2  are face to face. This downward tension on the power supply  5  comes from the tin solders inside the through holes “e” and forms a stronger and more secure electrically conductive between the LED light strip  2  and the power supply  5 . 
     Referring to  FIG. 12 , in one embodiment, the soldering pads “b” of the LED light strip  2  are two separate pads to electrically connect the positive and negative electrodes of the bendable circuit sheet of the LED light strip  2 , respectively. The size of the soldering pads “b” may be, for example, about 3.5×2 mm 2 . The printed circuit board of the power supply  5  is corresponding provided with soldering pads “a” having reserved tin solders and the height of the tin solders suitable for subsequent automatic soldering bonding process is generally, for example, about 0.1 to 0.7 mm, in some embodiments 0.3 to 0.5 mm, and in some even more preferable embodiments about 0.4 mm. An electrically insulating through hole “c” may be formed between the two soldering pads “b” to isolate and prevent the two soldering pads from electrically short during soldering. Furthermore, an extra positioning opening “d” may also be provided behind the electrically insulating through hole “c” to allow an automatic soldering machine to quickly recognize the position of the soldering pads “b”. 
     For the sake of achieving scalability and compatibility, the amount of the soldering pads “b” on each end of the LED light strip  2  may be more than one such as two, three, four, or more than four. When there is only one soldering pad “b” provided at each end of the LED light strip  2 , the two ends of the LED light strip  2  are electrically connected to the power supply  5  to form a loop, and various electrical components can be used. For example, a capacitance may be replaced by an inductance to perform current regulation. Referring to  FIGS. 13 to 16 , when each end of the LED light strip  2  has three soldering pads, the third soldering pad can be grounded; when each end of the LED light strip  2  has four soldering pads, the fourth soldering pad can be used as a signal input terminal. Correspondingly, the power supply  5  should have the same amount of soldering pads “a” as that of the soldering pads “b” on the LED light strip  2 . As long as electrical short between the soldering pads “b” can be prevented, the soldering pads “b” should be arranged according to the dimension of the actual area for disposition, for example, three soldering pads can be arranged in a row or two rows. In other embodiments, the amount of the soldering pads “b” on the bendable circuit sheet of the LED light strip  2  may be reduced by rearranging the circuits on the bendable circuit sheet of the LED light strip  2 . The lesser the amount of the soldering pads, the easier the fabrication process becomes. On the other hand, a greater number of soldering pads may improve and secure the electrically conductive between the LED light strip  2  and the output terminal of the power supply  5 . 
     Referring to  FIG. 17 , in another embodiment, the soldering pads “b” each is formed with a through hole “e” having a diameter generally of about 1 to 2 mm, in some embodiments of about 1.2 to 1.8 mm, and in yet some embodiments of about 1.5 mm. The through hole “e” communicates the soldering pad “a” with the soldering pad “b” so that the tin solder on the soldering pads “a” passes through the through holes “e” and finally reach the soldering pads “b”. A smaller through holes “e” would make it difficult for the tin solder to pass. The tin solder accumulates around the through holes “e” upon exiting the through holes “e” and condense to form a solder ball “g” with a larger diameter than that of the through holes “e” upon condensing. Such a solder ball “g” functions as a rivet to further increase the stability of the electrically conductive between the soldering pads “a” on the power supply  5  and the soldering pads “b” on the LED light strip  2 . 
     Referring to  FIGS. 18 to 19 , in other embodiments, when a distance from the through hole “e” to the side edge of the LED light strip  2  is less than 1 mm, the tin solder may pass through the through hole “e” to accumulate on the periphery of the through hole “e”, and extra tin solder may spill over the soldering pads “b” to reflow along the side edge of the LED light strip  2  and join the tin solder on the soldering pads “a” of the power supply  5 . The tin solder then condenses to form a structure like a rivet to firmly secure the LED light strip  2  onto the printed circuit board of the power supply  5  such that reliable electric connection is achieved. Referring to  FIGS. 20 and 21 , in another embodiment, the through hole “e” can be replaced by a notch “f” formed at the side edge of the soldering pads “b” for the tin solder to easily pass through the notch “f” and accumulate on the periphery of the notch “f” and to form a solder ball with a larger diameter than that of the notch “e” upon condensing. Such a solder ball may be formed like a C-shape rivet to enhance the secure capability of the electrically connecting structure. 
     Referring to  FIGS. 22 and 23 , in another embodiment, the LED light strip  2  and the power supply  5  may be connected by utilizing a circuit board assembly  25  instead of soldering bonding. The circuit board assembly  25  has a long circuit sheet  251  and a short circuit board  253  that are adhered to each other with the short circuit board  253  being adjacent to the side edge of the long circuit sheet  251 . The short circuit board  253  may be provided with power supply module  250  to form the power supply  5 . The short circuit board  253  is stiffer or more rigid than the long circuit sheet  251  to be able to support the power supply module  250 . 
     The long circuit sheet  251  may be the bendable circuit sheet of the LED light strip including a metal layer  2   a  as shown in  FIG. 10 . The metal layer  2   a  of the long circuit sheet  251  and the power supply module  250  may be electrically connected in various manners depending on the demand in practice. As shown in  FIG. 22 , the power supply module  250  and the long circuit sheet  251  having the metal layer  2   a  on surface are on the same side of the short circuit board  253  such that the power supply module  250  is directly connected to the long circuit sheet  251 . As shown in  FIG. 23 , alternatively, the power supply module  250  and the long circuit sheet  251  including the metal layer  2   a  on surface are on opposite sides of the short circuit board  253  such that the power supply module  250  is directly connected to the short circuit board  253  and indirectly connected to the metal layer  2   a  of the LED light strip  2  by way of the short circuit board  253 . 
     As shown in  FIG. 22 , in one embodiment, the long circuit sheet  251  and the short circuit board  253  are adhered together in the first place, and the power supply module  250  is subsequently mounted on the metal layer  2   a  of the long circuit sheet  251  serving as the LED light strip  2 . The long circuit sheet  251  of the LED light strip  2  herein is not limited to include only one metal layer  2   a  and may further include another metal layer such as the metal layer  2   c  shown in  FIG. 48 . The light sources  202  are disposed on the metal layer  2   a  of the LED light strip  2  and electrically connected to the power supply  5  by way of the metal layer  2   a . As shown in  FIG. 23 , in another embodiment, the long circuit sheet  251  of the LED light strip  2  may include a metal layer  2   a  and a dielectric layer  2   b . The dielectric layer  2   b  may be adhered to the short circuit board  253  in a first place and the metal layer  2   a  is subsequently adhered to the dielectric layer  2   b  and extends to the short circuit board  253 . All these embodiments are within the scope of applying the circuit board assembly concept of the present invention. 
     In the above-mentioned embodiments, the short circuit board  253  may have a length generally of about 15 mm to about 40 mm and in some embodiments about 19 mm to about 36 mm, while the long circuit sheet  251  may have a length generally of about 800 mm to about 2800 mm and in some embodiments of about 1200 mm to about 2400 mm. A ratio of the length of the short circuit board  253  to the length of the long circuit sheet  251  ranges from, for example, about 1:20 to about 1:200. 
     When the ends of the LED light strip  2  are not fixed on the inner surface of the glass tube  1 , the connection between the LED light strip  2  and the power supply  5  via soldering bonding could not firmly support the power supply  5 , and it may be necessary to dispose the power supply  5  inside the end cap  3 . For example, a longer end cap to have enough space for receiving the power supply  5  would be needed. However, this will reduce the length of the glass tube under the prerequisite that the total length of the LED tube lamp is fixed according to the product standard, and may therefore decrease the effective illuminating areas. 
     Next, examples of the circuit design and using of the power supply module  250  are described as follows. 
       FIG. 28A  is a block diagram of a power supply module  250  in an LED tube lamp according to an embodiment of the present invention. Referring to  FIG. 28A , an AC power supply  508  is used to supply an AC supply signal, and may be an AC powerline with a voltage rating, for example, in 100-277 volts and a frequency rating, for example, of 50 or 60 Hz. A lamp driving circuit  505  receives and then converts the AC supply signal into an AC driving signal as an external driving signal. Lamp driving circuit  505  may be for example an electronic ballast used to convert the AC powerline into a high-frequency high-voltage AC driving signal. Common types of electronic ballast include instant-start ballast, program-start or rapid-start ballast, etc., which may all be applicable to the LED tube lamp of the present invention. The voltage of the AC driving signal is likely higher than 300 volts, and is in some embodiments in the range of about 400-700 volts. The frequency of the AC driving signal is likely higher than 10 k Hz, and is in some embodiments in the range of about 20 k-50 k Hz. The LED tube lamp  500  receives an external driving signal and is thus driven to emit light. In one embodiment, the external driving signal comprises the AC driving signal from lamp driving circuit  505 . In one embodiment, LED tube lamp  500  is in a driving environment in which it is power-supplied at its one end cap having two conductive pins  501  and  502 , which are coupled to lamp driving circuit  505  to receive the AC driving signal. The two conductive pins  501  and  502  may be electrically connected to, either directly or indirectly, the lamp driving circuit  505 . 
     It is worth noting that lamp driving circuit  505  may be omitted and is therefore depicted by a dotted line. In one embodiment, if lamp driving circuit  505  is omitted, AC power supply  508  is directly connected to pins  501  and  502 , which then receive the AC supply signal as an external driving signal. 
     In addition to the above use with a single-end power supply, LED tube lamp  500  may instead be used with a dual-end power supply to one pin at each of the two ends of an LED lamp tube.  FIG. 28B  is a block diagram of a power supply module  250  in an LED tube lamp according to one embodiment of the present invention. Referring to  FIG. 28B , compared to that shown in  FIG. 28A , pins  501  and  502  are respectively disposed at the two opposite end caps of LED tube lamp  500 , forming a single pin at each end of LED tube lamp  500 , with other components and their functions being the same as those in  FIG. 28A . 
       FIG. 28C  is a block diagram of an LED lamp according to one embodiment of the present invention. Referring to  FIG. 28C , the power supply module of the LED lamp summarily includes a rectifying circuit  510 , a filtering circuit  520 . Rectifying circuit  510  is coupled to pins  501  and  502  to receive and then rectify an external driving signal, so as to output a rectified signal at output terminals  511  and  512 . The external driving signal may be the AC driving signal or the AC supply signal described with reference to  FIGS. 28A and 28B , or may even be a DC signal, which embodiments do not alter the LED lamp of the present invention. Filtering circuit  520  is coupled to the first rectifying circuit for filtering the rectified signal to produce a filtered signal, as recited in the claims. For instance, filtering circuit  520  is coupled to terminals  511  and  512  to receive and then filter the rectified signal, so as to output a filtered signal at output terminals  521  and  522 . LED lighting module  530  is coupled to filtering circuit  520 , to receive the filtered signal for emitting light. For instance, LED lighting module  530  may be a circuit coupled to terminals  521  and  522  to receive the filtered signal and thereby to drive an LED unit (not shown) in LED lighting module  530  to emit light. Details of these operations are described in below descriptions of certain embodiments. 
     It is worth noting that although there are two output terminals  511  and  512  and two output terminals  521  and  522  in embodiments of these Figs., in practice the number of ports or terminals for coupling between rectifying circuit  510 , filtering circuit  520 , and LED lighting module  530  may be one or more depending on the needs of signal transmission between the circuits or devices. 
     In addition, the power supply module of the LED lamp described in  FIG. 28C , and embodiments of the power supply module of an LED lamp described below, may each be used in the LED tube lamp  500  in  FIGS. 28A and 28B , and may instead be used in any other type of LED lighting structure having two conductive pins used to conduct power, such as LED light bulbs, personal area lights (PAL), plug-in LED lamps with different types of bases (such as types of PL-S, PL-D, PL-T, PL-L, etc.), etc. 
       FIG. 28D  is a block diagram of a power supply module  250  in an LED tube lamp according to an embodiment of the present invention. Referring to  FIG. 28D , an AC power supply  508  is used to supply an AC supply signal. A lamp driving circuit  505  receives and then converts the AC supply signal into an AC driving signal. An LED tube lamp  500  receives an AC driving signal from lamp driving circuit  505  and is thus driven to emit light. In this embodiment, LED tube lamp  500  is power-supplied at its both end caps respectively having two pins  501  and  502  and two pins  503  and  504 , which are coupled to lamp driving circuit  505  to concurrently receive the AC driving signal to drive an LED unit (not shown) in LED tube lamp  500  to emit light. AC power supply  508  may be e.g. the AC powerline, and lamp driving circuit  505  may be a stabilizer or an electronic ballast. 
       FIG. 28E  is a block diagram of an LED lamp according to an embodiment of the present invention. Referring to  FIG. 28E , the power supply module of the LED lamp summarily includes a rectifying circuit  510 , a filtering circuit  520 , and a filtering circuit  540 . Rectifying circuit  510  is coupled to pins  501  and  502  to receive and then rectify an external driving signal conducted by pins  501  and  502 . Rectifying circuit  540  is coupled to pins  503  and  504  to receive and then rectify an external driving signal conducted by pins  503  and  504 . Therefore, the power supply module of the LED lamp may include two rectifying circuits  510  and  540  configured to output a rectified signal at output terminals  511  and  512 . Filtering circuit  520  is coupled to terminals  511  and  512  to receive and then filter the rectified signal, so as to output a filtered signal at output terminals  521  and  522 . LED lighting module  530  is coupled to terminals  521  and  522  to receive the filtered signal and thereby to drive an LED unit (not shown) in LED lighting module  530  to emit light. 
     The power supply module of the LED lamp in this embodiment of  FIG. 28E  may be used in LED tube lamp  500  with a dual-end power supply in  FIG. 28D . It is worth noting that since the power supply module of the LED lamp comprises rectifying circuits  510  and  540 , the power supply module of the LED lamp may be used in LED tube lamp  500  with a single-end power supply in  FIGS. 28A and 28B , to receive an external driving signal (such as the AC supply signal or the AC driving signal described above). The power supply module of an LED lamp in this embodiment and other embodiments herein may also be used with a DC driving signal. 
       FIG. 29A  is a schematic diagram of a rectifying circuit according to an embodiment of the present invention. Referring to  FIG. 29A , rectifying circuit  610  includes rectifying diodes  611 ,  612 ,  613 , and  614 , configured to full-wave rectify a received signal. Diode  611  has an anode connected to output terminal  512 , and a cathode connected to pin  502 . Diode  612  has an anode connected to output terminal  512 , and a cathode connected to pin  501 . Diode  613  has an anode connected to pin  502 , and a cathode connected to output terminal  511 . Diode  614  has an anode connected to pin  501 , and a cathode connected to output terminal  511 . 
     When pins  501  and  502  receive an AC signal, rectifying circuit  610  operates as follows. During the connected AC signal&#39;s positive half cycle, the AC signal is input through pin  501 , diode  614 , and output terminal  511  in sequence, and later output through output terminal  512 , diode  611 , and pin  502  in sequence. During the connected AC signal&#39;s negative half cycle, the AC signal is input through pin  502 , diode  613 , and output terminal  511  in sequence, and later output through output terminal  512 , diode  612 , and pin  501  in sequence. Therefore, during the connected AC signal&#39;s full cycle, the positive pole of the rectified signal produced by rectifying circuit  610  remains at output terminal  511 , and the negative pole of the rectified signal remains at output terminal  512 . Accordingly, the rectified signal produced or output by rectifying circuit  610  is a full-wave rectified signal. 
     When pins  501  and  502  are coupled to a DC power supply to receive a DC signal, rectifying circuit  610  operates as follows. When pin  501  is coupled to the anode of the DC supply and pin  502  to the cathode of the DC supply, the DC signal is input through pin  501 , diode  614 , and output terminal  511  in sequence, and later output through output terminal  512 , diode  611 , and pin  502  in sequence. When pin  501  is coupled to the cathode of the DC supply and pin  502  to the anode of the DC supply, the DC signal is input through pin  502 , diode  613 , and output terminal  511  in sequence, and later output through output terminal  512 , diode  612 , and pin  501  in sequence. Therefore, no matter what the electrical polarity of the DC signal is between pins  501  and  502 , the positive pole of the rectified signal produced by rectifying circuit  610  remains at output terminal  511 , and the negative pole of the rectified signal remains at output terminal  512 . 
     Therefore, rectifying circuit  610  in this embodiment can output or produce a proper rectified signal regardless of whether the received input signal is an AC or DC signal. 
       FIG. 29B  is a schematic diagram of a rectifying circuit according to an embodiment of the present invention. Referring to  FIG. 29B , rectifying circuit  710  includes rectifying diodes  711  and  712 , configured to half-wave rectify a received signal. Diode  711  has an anode connected to pin  502 , and a cathode connected to output terminal  511 . Diode  712  has an anode connected to output terminal  511 , and a cathode connected to pin  501 . Output terminal  512  may be omitted or grounded depending on actual applications. 
     Next, exemplary operation(s) of rectifying circuit  710  is described as follows. 
     In one embodiment, during a received AC signal&#39;s positive half cycle, the electrical potential at pin  501  is higher than that at pin  502 , so diodes  711  and  712  are both in a cutoff state as being reverse-biased, making rectifying circuit  710  not outputting a rectified signal. During a received AC signal&#39;s negative half cycle, the electrical potential at pin  501  is lower than that at pin  502 , so diodes  711  and  712  are both in a conducting state as being forward-biased, allowing the AC signal to be input through diode  711  and output terminal  511 , and later output through output terminal  512 , a ground terminal, or another end of the LED tube lamp not directly connected to rectifying circuit  710 . Accordingly, the rectified signal produced or output by rectifying circuit  710  is a half-wave rectified signal. 
       FIG. 29C  is a schematic diagram of a rectifying circuit according to an embodiment of the present invention. Referring to  FIG. 29C , rectifying circuit  810  includes a rectifying unit  815  and a terminal adapter circuit  541 . In this embodiment, rectifying unit  815  comprises a half-wave rectifier circuit including diodes  811  and  812  and configured to half-wave rectify. Diode  811  has an anode connected to an output terminal  512 , and a cathode connected to a half-wave node  819 . Diode  812  has an anode connected to half-wave node  819 , and a cathode connected to an output terminal  511 . Terminal adapter circuit  541  is coupled to half-wave node  819  and pins  501  and  502 , to transmit a signal received at pin  501  and/or pin  502  to half-wave node  819 . By means of the terminal adapting function of terminal adapter circuit  541 , rectifying circuit  810  allows of two input terminals (connected to pins  501  and  502 ) and two output terminals  511  and  512 . 
     Next, in certain embodiments, rectifying circuit  810  operates as follows. 
     During a received AC signal&#39;s positive half cycle, the AC signal may be input through pin  501  or  502 , terminal adapter circuit  541 , half-wave node  819 , diode  812 , and output terminal  511  in sequence, and later output through another end or circuit of the LED tube lamp. During a received AC signal&#39;s negative half cycle, the AC signal may be input through another end or circuit of the LED tube lamp, and later output through output terminal  512 , diode  811 , half-wave node  819 , terminal adapter circuit  541 , and pin  501  or  502  in sequence. 
     It&#39;s worth noting that terminal adapter circuit  541  may comprise a resistor, a capacitor, an inductor, or any combination thereof, for performing functions of voltage/current regulation or limiting, types of protection, current/voltage regulation, etc. Descriptions of these functions are presented below. 
     In practice, rectifying unit  815  and terminal adapter circuit  541  may be interchanged in position (as shown in  FIG. 29D ), without altering the function of half-wave rectification.  FIG. 29D  is a schematic diagram of a rectifying circuit according to an embodiment of the present invention. Referring to  FIG. 29D , diode  811  has an anode connected to pin  502  and diode  812  has a cathode connected to pin  501 . A cathode of diode  811  and an anode of diode  812  are connected to half-wave node  819 . Terminal adapter circuit  541  is coupled to half-wave node  819  and output terminals  511  and  512 . During a received AC signal&#39;s positive half cycle, the AC signal may be input through another end or circuit of the LED tube lamp, and later output through output terminal  512  or  512 , terminal adapter circuit  541 , half-wave node  819 , diode  812 , and pin  501  in sequence. During a received AC signal&#39;s negative half cycle, the AC signal may be input through pin  502 , diode  811 , half-wave node  819 , terminal adapter circuit  541 , and output node  511  or  512  in sequence, and later output through another end or circuit of the LED tube lamp. 
     It is worth noting that terminal adapter circuit  541  in embodiments shown in  FIGS. 29C and 29D  may be omitted and is therefore depicted by a dotted line. If terminal adapter circuit  541  of  FIG. 29C  is omitted, pins  501  and  502  will be coupled to half-wave node  819 . If terminal adapter circuit  541  of  FIG. 29D  is omitted, output terminals  511  and  512  will be coupled to half-wave node  819 . 
     Rectifying circuit  510  as shown and explained in  FIGS. 29A-D  can constitute or be the rectifying circuit  540  shown in  FIG. 28E , as having pins  503  and  504  for conducting instead of pins  501  and  502 . 
     Next, an explanation follows as to choosing embodiments and their combinations of rectifying circuits  510  and  540 , with reference to  FIGS. 28C and 28E . 
     Rectifying circuit  510  in embodiments shown in  FIG. 28C  may comprise the rectifying circuit  610  in  FIG. 29A . 
     Rectifying circuits  510  and  540  in embodiments shown in  FIG. 28E  may each comprise any one of the rectifying circuits in  FIGS. 29A-D , and terminal adapter circuit  541  in  FIGS. 29C-D  may be omitted without altering the rectification function needed in an LED tube lamp. When rectifying circuits  510  and  540  each comprise a half-wave rectifier circuit described in  FIGS. 29B-D , during a received AC signal&#39;s positive or negative half cycle, the AC signal may be input from one of rectifying circuits  510  and  540 , and later output from the other rectifying circuit  510  or  540 . Further, when rectifying circuits  510  and  540  each comprise the rectifying circuit described in  FIG. 29C or 50D , or when they comprise the rectifying circuits in  FIGS. 29C and 29D  respectively, only one terminal adapter circuit  541  may be needed for functions of voltage/current regulation or limiting, types of protection, current/voltage regulation, etc. within rectifying circuits  510  and  540 , omitting another terminal adapter circuit  541  within rectifying circuit  510  or  540 . 
       FIG. 30A  is a schematic diagram of the terminal adapter circuit according to an embodiment of the present invention. Referring to  FIG. 30A , terminal adapter circuit  641  comprises a capacitor  642  having an end connected to pins  501  and  502 , and another end connected to half-wave node  819 . Capacitor  642  has an equivalent impedance to an AC signal, which impedance increases as the frequency of the AC signal decreases, and decreases as the frequency increases. Therefore, capacitor  642  in terminal adapter circuit  641  in this embodiment works as a high-pass filter. Further, terminal adapter circuit  641  is connected in series to an LED unit in the LED tube lamp, producing an equivalent impedance of terminal adapter circuit  641  to perform a current/voltage limiting function on the LED unit, thereby preventing damaging of the LED unit by an excessive voltage across and/or current in the LED unit. In addition, choosing the value of capacitor  642  according to the frequency of the AC signal can further enhance voltage/current regulation. 
     It&#39;s worth noting that terminal adapter circuit  641  may further include a capacitor  645  and/or capacitor  646 . Capacitor  645  has an end connected to half-wave node  819 , and another end connected to pin  503 . Capacitor  646  has an end connected to half-wave node  819 , and another end connected to pin  504 . For example, half-wave node  819  may be a common connective node between capacitors  645  and  646 . And capacitor  642  acting as a current regulating capacitor is coupled to the common connective node and pins  501  and  502 . In such a structure, series-connected capacitors  642  and  645  exist between one of pins  501  and  502  and pin  503 , and/or series-connected capacitors  642  and  646  exist between one of pins  501  and  502  and pin  504 . Through equivalent impedances of series-connected capacitors, voltages from the AC signal are divided. Referring to  FIGS. 28E and 30A , according to ratios between equivalent impedances of the series-connected capacitors, the voltages respectively across capacitor  642  in rectifying circuit  510 , filtering circuit  520 , and LED lighting module  530  can be controlled, making the current flowing through an LED module in LED lighting module  530  being limited within a current rating, and then protecting/preventing filtering circuit  520  and LED lighting module  530  from being damaged by excessive voltages. 
       FIG. 30B  is a schematic diagram of the terminal adapter circuit according to an embodiment of the present invention. Referring to  FIG. 30B , terminal adapter circuit  741  comprises capacitors  743  and  744 . Capacitor  743  has an end connected to pin  501 , and another end connected to half-wave node  819 . Capacitor  744  has an end connected to pin  502 , and another end connected to half-wave node  819 . Compared to terminal adapter circuit  641  in  FIG. 30A , terminal adapter circuit  741  has capacitors  743  and  744  in place of capacitor  642 . Capacitance values of capacitors  743  and  744  may be the same as each other, or may differ from each other depending on the magnitudes of signals to be received at pins  501  and  502 . 
     Similarly, terminal adapter circuit  741  may further comprise a capacitor  745  and/or a capacitor  746 , respectively connected to pins  503  and  504 . Thus, each of pins  501  and  502  and each of pins  503  and  504  may be connected in series to a capacitor, to achieve the functions of voltage division and other protections. 
       FIG. 30C  is a schematic diagram of the terminal adapter circuit according to an embodiment of the present invention. Referring to  FIG. 30C , terminal adapter circuit  841  comprises capacitors  842 ,  843 , and  844 . Capacitors  842  and  843  are connected in series between pin  501  and half-wave node  819 . Capacitors  842  and  844  are connected in series between pin  502  and half-wave node  819 . In such a circuit structure, if any one of capacitors  842 ,  843 , and  844  is shorted, there is still at least one capacitor (of the other two capacitors) between pin  501  and half-wave node  819  and between pin  502  and half-wave node  819 , which performs a current-limiting function. Therefore, in the event that a user accidentally gets an electric shock, this circuit structure will prevent an excessive current flowing through and then seriously hurting the body of the user. 
     Similarly, terminal adapter circuit  841  may further comprise a capacitor  845  and/or a capacitor  846 , respectively connected to pins  503  and  504 . Thus, each of pins  501  and  502  and each of pins  503  and  504  may be connected in series to a capacitor, to achieve the functions of voltage division and other protections. 
       FIG. 30D  is a schematic diagram of the terminal adapter circuit according to an embodiment of the present invention. Referring to  FIG. 30D , terminal adapter circuit  941  comprises fuses  947  and  948 . Fuse  947  has an end connected to pin  501 , and another end connected to half-wave node  819 . Fuse  948  has an end connected to pin  502 , and another end connected to half-wave node  819 . With the fuses  947  and  948 , when the current through each of pins  501  and  502  exceeds a current rating of a corresponding connected fuse  947  or  948 , the corresponding fuse  947  or  948  will accordingly melt and then break the circuit to achieve overcurrent protection. 
     Each of the embodiments of the terminal adapter circuits as in rectifying circuits  510  and  810  coupled to pins  501  and  502  and shown and explained above can be used or included in the rectifying circuit  540  shown in  FIG. 28E , as when conductive pins  503  and  504  and conductive pins  501  and  502  are interchanged in position. 
     Capacitance values of the capacitors in the embodiments of the terminal adapter circuits shown and described above are in some embodiments in the range, for example, of about 100 pF-100 nF. Also, a capacitor used in embodiments may be equivalently replaced by two or more capacitors connected in series or parallel. For example, each of capacitors  642  and  842  may be replaced by two series-connected capacitors, one having a capacitance value chosen from the range, for example of about 1.0 nF to about 2.5 nF and which may be in some embodiments preferably 1.5 nF, and the other having a capacitance value chosen from the range, for example of about 1.5 nF to about 3.0 nF, and which is in some embodiments about 2.2 nF. 
       FIG. 31A  is a schematic diagram of an LED module according to an embodiment of the present invention. Referring to  FIG. 31A , LED module  630  has an anode connected to the filtering output terminal  521 , has a cathode connected to the filtering output terminal  522 , and comprises at least one LED unit  632 . When two or more LED units are included, they are connected in parallel. The anode of each LED unit  632  is connected to the anode of LED module  630  and thus output terminal  521 , and the cathode of each LED unit  632  is connected to the cathode of LED module  630  and thus output terminal  522 . Each LED unit  632  includes at least one LED  631 . When multiple LEDs  631  are included in an LED unit  632 , they are connected in series, with the anode of the first LED  631  connected to the anode of this LED unit  632 , and the cathode of the first LED  631  connected to the next or second LED  631 . And the anode of the last LED  631  in this LED unit  632  is connected to the cathode of a previous LED  631 , with the cathode of the last LED  631  connected to the cathode of this LED unit  632 . 
     It&#39;s worth noting that LED module  630  may produce a current detection signal  5531  reflecting a magnitude of current through LED module  630  and used for controlling or detecting on the LED module  630 . 
       FIG. 31B  is a schematic diagram of an LED module according to an embodiment of the present invention. Referring to  FIG. 31B , LED module  630  has an anode connected to the filtering output terminal  521 , has a cathode connected to the filtering output terminal  522 , and comprises at least two LED units  732 , with the anode of each LED unit  732  connected to the anode of LED module  630 , and the cathode of each LED unit  732  connected to the cathode of LED module  630 . Each LED unit  732  includes at least two LEDs  731  connected in the same way as described in  FIG. 31A . For example, the anode of the first LED  731  in an LED unit  732  is connected to the anode of this LED unit  732 , the cathode of the first LED  731  is connected to the anode of the next or second LED  731 , and the cathode of the last LED  731  is connected to the cathode of this LED unit  732 . Further, LED units  732  in an LED module  630  are connected to each other in this embodiment. All of the n-th LEDs  731  respectively of the LED units  732  are connected by every anode of every n-th LED  731  in the LED units  732 , and by every cathode of every n-th LED  731 , where n is a positive integer. In this way, the LEDs in LED module  630  in this embodiment are connected in the form of a mesh. 
     The LED lighting module  530  of the above embodiments includes LED module  630 , but doesn&#39;t include a driving circuit for the LED module  630 . 
     Similarly, LED module  630  in this embodiment may produce a current detection signal  5531  reflecting a magnitude of current through LED module  630  and used for controlling or detecting on the LED module  630 . 
     In actual practice, the number of LEDs  731  included by an LED unit  732  is in some embodiments in the range of 15-25, and is may be preferably in the range of 18-22. 
       FIG. 31C  is a plan view of a circuit layout of the LED module according to an embodiment of the present invention. Referring to  FIG. 31C , in this embodiment LEDs  831  are connected in the same way as described in  FIG. 31B , and three LED units are assumed in LED module  630  and described as follows for illustration. A positive conductive line  834  and a negative conductive line  835  are to receive a driving signal, for supplying power to the LEDs  831 . For example, positive conductive line  834  may be coupled to the filtering output terminal  521  of the filtering circuit  520  described above, and negative conductive line  835  coupled to the filtering output terminal  522  of the filtering circuit  520 , to receive a filtered signal. For the convenience of illustration, all three of the n-th LEDs  831  respectively of the three LED units are grouped as an LED set  833  in  FIG. 31C . 
     Positive conductive line  834  connects the three first LEDs  831  respectively of the leftmost three LED units, at the anodes on the left sides of the three first LEDs  831  as shown in the leftmost LED set  833  of  FIG. 31C . Negative conductive line  835  connects the three last LEDs  831  respectively of the leftmost three LED units, at the cathodes on the right sides of the three last LEDs  831  as shown in the rightmost LED set  833  of  FIG. 31C . And of the three LED units, the cathodes of the three first LEDs  831 , the anodes of the three last LEDs  831 , and the anodes and cathodes of all the remaining LEDs  831  are connected by conductive lines or parts  839 . 
     For example, the anodes of the three LEDs  831  in the leftmost LED set  833  may be connected together by positive conductive line  834 , and their cathodes may be connected together by a leftmost conductive part  839 . The anodes of the three LEDs  831  in the second leftmost LED set  833  are also connected together by the leftmost conductive part  839 , whereas their cathodes are connected together by a second leftmost conductive part  839 . Since the cathodes of the three LEDs  831  in the leftmost LED set  833  and the anodes of the three LEDs  831  in the second leftmost LED set  833  are connected together by the same leftmost conductive part  839 , in each of the three LED units the cathode of the first LED  831  is connected to the anode of the next or second LED  831 , with the remaining LEDs  831  also being connected in the same way. Accordingly, all the LEDs  831  of the three LED units are connected to form the mesh as shown in  FIG. 31B . 
     It&#39;s worth noting that in this embodiment the length  836  of a portion of each conductive part  839  that immediately connects to the anode of an LED  831  is smaller than the length  837  of another portion of each conductive part  839  that immediately connects to the cathode of an LED  831 , making the area of the latter portion immediately connecting to the cathode larger than that of the former portion immediately connecting to the anode. The length  837  may be smaller than a length  838  of a portion of each conductive part  839  that immediately connects the cathode of an LED  831  and the anode of the next LED  831 , making the area of the portion of each conductive part  839  that immediately connects a cathode and an anode larger than the area of any other portion of each conductive part  839  that immediately connects to only a cathode or an anode of an LED  831 . Due to the length differences and area differences, this layout structure improves heat dissipation of the LEDs  831 . 
     In some embodiments, positive conductive line  834  includes a lengthwise portion  834   a , and negative conductive line  835  includes a lengthwise portion  835   a , which are conducive to making the LED module have a positive “+” connective portion and a negative “−” connective portion at each of the two ends of the LED module, as shown in  FIG. 31C . Such a layout structure allows for coupling any of other circuits of the power supply module of the LED lamp, including e.g. filtering circuit  520  and rectifying circuits  510  and  540 , to the LED module through the positive connective portion and/or the negative connective portion at each or both ends of the LED lamp. Thus, the layout structure increases the flexibility in arranging actual circuits in the LED lamp. 
       FIG. 31D  is a plan view of a circuit layout of the LED module according to another embodiment of the present invention. Referring to  FIG. 31D , in this embodiment LEDs  931  are connected in the same way as described in  FIG. 31A , and three LED units each including 7 LEDs  931  are assumed in LED module  630  and described as follows for illustration. A positive conductive line  934  and a negative conductive line  935  are to receive a driving signal, for supplying power to the LEDs  931 . For example, positive conductive line  934  may be coupled to the filtering output terminal  521  of the filtering circuit  520  described above, and negative conductive line  935  coupled to the filtering output terminal  522  of the filtering circuit  520 , to receive a filtered signal. For the convenience of illustration, all seven LEDs  931  of each of the three LED units are grouped as an LED set  932  in  FIG. 31D . Thus, there are three LED sets  932  corresponding to the three LED units. 
     Positive conductive line  934  connects to the anode on the left side of the first or leftmost LED  931  of each of the three LED sets  932 . Negative conductive line  935  connects to the cathode on the right side of the last or rightmost LED  931  of each of the three LED sets  932 . In each LED set  932 , of two consecutive LEDs  931  the LED  931  on the left has a cathode connected by a conductive part  939  to an anode of the LED  931  on the right. By such a layout, the LEDs  931  of each LED set  932  are connected in series. 
     It&#39;s also worth noting that a conductive part  939  may be used to connect an anode and a cathode respectively of two consecutive LEDs  931 . Negative conductive line  935  connects to the cathode of the last or rightmost LED  931  of each of the three LED sets  932 . And positive conductive line  934  connects to the anode of the first or leftmost LED  931  of each of the three LED sets  932 . Therefore, as shown in  FIG. 31D , the length (and thus area) of the conductive part  939  is larger than that of the portion of negative conductive line  935  immediately connecting to a cathode, which length (and thus area) is then larger than that of the portion of positive conductive line  934  immediately connecting to an anode. For example, the length  938  of the conductive part  939  may be larger than the length  937  of the portion of negative conductive line  935  immediately connecting to a cathode of an LED  931 , which length  937  is then larger than the length  936  of the portion of positive conductive line  934  immediately connecting to an anode of an LED  931 . Such a layout structure improves heat dissipation of the LEDs  931  in LED module  630 . 
     Positive conductive line  934  may include a lengthwise portion  934   a , and negative conductive line  935  may include a lengthwise portion  935   a , which are conducive to making the LED module have a positive “+” connective portion and a negative “−” connective portion at each of the two ends of the LED module, as shown in  FIG. 31D . Such a layout structure allows for coupling any of other circuits of the power supply module of the LED lamp, including e.g. filtering circuit  520  and rectifying circuits  510  and  540 , to the LED module through the positive connective portion  934   a  and/or the negative connective portion  935   a  at each or both ends of the LED lamp. Thus, the layout structure increases the flexibility in arranging actual circuits in the LED lamp. 
     Further, the circuit layouts as shown in  FIGS. 31C and 31D  may be implemented with a bendable circuit sheet or substrate, which may even be called flexible circuit board depending on its specific definition used. For example, the bendable circuit sheet may comprise one conductive layer where positive conductive line  834 , positive lengthwise portion  834   a , negative conductive line  835 , negative lengthwise portion  835   a , and conductive parts  839  shown in  FIG. 31C , and positive conductive line  934 , positive lengthwise portion  934   a , negative conductive line  935 , negative lengthwise portion  935   a , and conductive parts  939  shown in  FIG. 31D  are formed by the method of etching. 
       FIG. 31E  is a plan view of a circuit layout of the LED module according to another embodiment of the present invention. The layout structures of the LED module in  FIGS. 31E and 31C  each correspond to the same way of connecting LEDs  831  as that shown in  FIG. 31B , but the layout structure in  FIG. 31E  comprises two conductive layers, instead of only one conductive layer for forming the circuit layout as shown in  FIG. 31C . Referring to  FIG. 31E , the main difference from the layout in  FIG. 31C  is that positive conductive line  834  and negative conductive line  835  have a lengthwise portion  834   a  and a lengthwise portion  835   a , respectively, that are formed in a second conductive layer instead. The difference is elaborated as follows. 
     Referring to  FIG. 31E , the bendable circuit sheet of the LED module comprises a first conductive layer  2   a  and a second conductive layer  2   c  electrically insulated from each other by a dielectric layer  2   b  (not shown). Of the two conductive layers, positive conductive line  834 , negative conductive line  835 , and conductive parts  839  in  FIG. 31E  are formed in first conductive layer  2   a  by the method of etching for electrically connecting the plurality of LED components  831  e.g. in a form of a mesh, whereas positive lengthwise portion  834   a  and negative lengthwise portion  835   a  are formed in second conductive layer  2   c  by etching for electrically connecting to (the filtering output terminal of) the filtering circuit. Further, positive conductive line  834  and negative conductive line  835  in first conductive layer  2   a  have via points  834   b  and via points  835   b , respectively, for connecting to second conductive layer  2   c . And positive lengthwise portion  834   a  and negative lengthwise portion  835   a  in second conductive layer  2   c  have via points  834   c  and via points  835   c , respectively. Via points  834   b  are positioned corresponding to via points  834   c , for connecting positive conductive line  834  and positive lengthwise portion  834   a . Via points  835   b  are positioned corresponding to via points  835   c , for connecting negative conductive line  835  and negative lengthwise portion  835   a . A preferable way of connecting the two conductive layers is to form a hole connecting each via point  834   b  and a corresponding via point  834   c , and to form a hole connecting each via point  835   b  and a corresponding via point  835   c , with the holes extending through the two conductive layers and the dielectric layer in-between. And positive conductive line  834  and positive lengthwise portion  834   a  can be electrically connected by welding metallic part(s) through the connecting hole(s), and negative conductive line  835  and negative lengthwise portion  835   a  can be electrically connected by welding metallic part(s) through the connecting hole(s). 
     Similarly, the layout structure of the LED module in  FIG. 31D  may alternatively have positive lengthwise portion  934   a  and negative lengthwise portion  935   a  disposed in a second conductive layer, to constitute a two-layer layout structure. 
     It&#39;s worth noting that the thickness of the second conductive layer of a two-layer bendable circuit sheet is in some embodiments larger than that of the first conductive layer, in order to reduce the voltage drop or loss along each of the positive lengthwise portion and the negative lengthwise portion disposed in the second conductive layer. Compared to a one-layer bendable circuit sheet, since a positive lengthwise portion and a negative lengthwise portion are disposed in a second conductive layer in a two-layer bendable circuit sheet, the width (between two lengthwise sides) of the two-layer bendable circuit sheet is or can be reduced. On the same fixture or plate in a production process, the number of bendable circuit sheets each with a shorter width that can be laid together at most is larger than the number of bendable circuit sheets each with a longer width that can be laid together at most. Thus, adopting a bendable circuit sheet with a shorter width can increase the efficiency of production of the LED module. And reliability in the production process, such as the accuracy of welding position when welding (materials on) the LED components, can also be improved, because a two-layer bendable circuit sheet can better maintain its shape. 
     As a variant of the above embodiments, a type of LED tube lamp is provided that has at least some of the electronic components of its power supply module disposed on a light strip of the LED tube lamp. For example, the technique of printed electronic circuit (PEC) can be used to print, insert, or embed at least some of the electronic components onto the light strip. 
     In one embodiment, all electronic components of the power supply module are disposed on the light strip. The production process may include or proceed with the following steps: preparation of the circuit substrate (e.g. preparation of a flexible printed circuit board); ink jet printing of metallic nano-ink; ink jet printing of active and passive components (as of the power supply module); drying/sintering; ink jet printing of interlayer bumps; spraying of insulating ink; ink jet printing of metallic nano-ink; ink jet printing of active and passive components (to sequentially form the included layers); spraying of surface bond pad(s); and spraying of solder resist against LED components. 
     In certain embodiments, if all electronic components of the power supply module are disposed on the light strip, electrical connection between terminal pins of the LED tube lamp and the light strip may be achieved by connecting the pins to conductive lines which are welded with ends of the light strip. In this case, another substrate for supporting the power supply module is not required, thereby allowing of an improved design or arrangement in the end cap(s) of the LED tube lamp. In some embodiments, (components of) the power supply module are disposed at two ends of the light strip, in order to significantly reduce the impact of heat generated from the power supply module&#39;s operations on the LED components. Since no substrate other than the light strip is used to support the power supply module in this case, the total amount of welding or soldering can be significantly reduced, improving the general reliability of the power supply module. 
     Another case is that some of all electronic components of the power supply module, such as some resistors and/or smaller size capacitors, are printed onto the light strip, and some bigger size components, such as some inductors and/or electrolytic capacitors, are disposed in the end cap(s). The production process of the light strip in this case may be the same as that described above. And in this case disposing some of all electronic components on the light strip is conducive to achieving a reasonable layout of the power supply module in the LED tube lamp, which may allow of an improved design in the end cap(s). 
     As a variant embodiment of the above, electronic components of the power supply module may be disposed on the light strip by a method of embedding or inserting, e.g. by embedding the components onto a bendable or flexible light strip. In some embodiments, this embedding may be realized by a method using copper-clad laminates (CCL) for forming a resistor or capacitor; a method using ink related to silkscreen printing; or a method of ink jet printing to embed passive components, wherein an ink jet printer is used to directly print inks to constitute passive components and related functionalities to intended positions on the light strip. Then through treatment by ultraviolet (UV) light or drying/sintering, the light strip is formed where passive components are embedded. The electronic components embedded onto the light strip include for example resistors, capacitors, and inductors. In other embodiments, active components also may be embedded. Through embedding some components onto the light strip, a reasonable layout of the power supply module can be achieved to allow of an improved design in the end cap(s), because the surface area on a printed circuit board used for carrying components of the power supply module is reduced or smaller, and as a result the size, weight, and thickness of the resulting printed circuit board for carrying components of the power supply module is also smaller or reduced. Also in this situation since welding points on the printed circuit board for welding resistors and/or capacitors if they were not to be disposed on the light strip are no longer used, the reliability of the power supply module is improved, in view of the fact that these welding points are most liable to (cause or incur) faults, malfunctions, or failures. Further, the length of conductive lines needed for connecting components on the printed circuit board is therefore also reduced, which allows of a more compact layout of components on the printed circuit board and thus improving the functionalities of these components. 
     Next, methods to produce embedded capacitors and resistors are explained as follows. 
     Usually, methods for manufacturing embedded capacitors employ or involve a concept called distributed or planar capacitance. The manufacturing process may include the following step(s). On a substrate of a copper layer a very thin insulation layer is applied or pressed, which is then generally disposed between a pair of layers including a power conductive layer and a ground layer. The very thin insulation layer makes the distance between the power conductive layer and the ground layer very short. A capacitance resulting from this structure can also be realized by a conventional technique of a plated-through hole. Basically, this step is used to create this structure comprising a big parallel-plate capacitor on a circuit substrate. 
     Of products of high electrical capacity, certain types of products employ distributed capacitances, and other types of products employ separate embedded capacitances. Through putting or adding a high dielectric-constant material such as barium titanate into the insulation layer, the high electrical capacity is achieved. 
     A usual method for manufacturing embedded resistors employ conductive or resistive adhesive. This may include, for example, a resin to which conductive carbon or graphite is added, which may be used as an additive or filler. The additive resin is silkscreen printed to an object location, and is then after treatment laminated inside the circuit board. The resulting resistor is connected to other electronic components through plated-through holes or microvias. Another method is called Ohmega-Ply, by which a two-metallic layer structure of a copper layer and a thin nickel alloy layer constitutes a layer resistor relative to a substrate. Then through etching the copper layer and nickel alloy layer, different types of nickel alloy resistors with copper terminals can be formed. These types of resistor are each laminated inside the circuit board. 
     In an embodiment, conductive wires/lines are directly printed in a linear layout on an inner surface of the LED glass lamp tube, with LED components directly attached on the inner surface and electrically connected by the conductive wires. In some embodiments, the LED components in the form of chips are directly attached over the conductive wires on the inner surface, and connective points are at terminals of the wires for connecting the LED components and the power supply module. After being attached, the LED chips may have fluorescent powder applied or dropped thereon, for producing white light or light of other color by the operating LED tube lamp. 
     In some embodiments, luminous efficacy of the LED or LED component is 80 lm/W or above, and in some embodiments, it may be preferably 120 lm/W or above. Certain more optimal embodiments may include a luminous efficacy of the LED or LED component of 160 lm/W or above. White light emitted by an LED component in the invention may be produced by mixing fluorescent powder with the monochromatic light emitted by a monochromatic LED chip. The white light in its spectrum has major wavelength ranges of 430-460 nm and 550-560 nm, or major wavelength ranges of 430-460 nm, 540-560 nm, and 620-640 nm. 
       FIG. 32A  is a block diagram of using a power supply module in an LED lamp according to an embodiment of the present invention. The embodiment of  FIG. 32A  includes rectifying circuits  510  and  540 , and a filtering circuit  520 , and further includes an anti-flickering circuit  550  coupled between filtering circuit  520  and an LED lighting module  530 . It&#39;s noted that rectifying circuit  540  may be omitted and is thus depicted in a dotted line in  FIG. 32A . 
     Anti-flickering circuit  550  is coupled to filtering output terminals  521  and  522 , to receive a filtered signal, and under specific circumstances to consume partial energy of the filtered signal so as to reduce (the incidence of) ripples of the filtered signal disrupting or interrupting the light emission of the LED lighting module  530 . In general, filtering circuit  520  has such filtering components as resistor(s) and/or inductor(s), and/or parasitic capacitors and inductors, which may form resonant circuits. Upon breakoff or stop of an AC power signal, as when the power supply of the LED lamp is turned off by a user, the amplitude(s) of resonant signals in the resonant circuits will decrease with time. But LEDs in the LED module of the LED lamp are unidirectional conduction devices and require a minimum conduction voltage for the LED module. When a resonant signal&#39;s trough value is lower than the minimum conduction voltage of the LED module, but its peak value is still higher than the minimum conduction voltage, the flickering phenomenon will occur in light emission of the LED module. In this case anti-flickering circuit  550  works by allowing a current matching a defined flickering current value of the LED component to flow through, consuming partial energy of the filtered signal which should be higher than the energy difference of the resonant signal between its peak and trough values, so as to reduce the flickering phenomenon. In certain embodiments, a preferred occasion for anti-flickering circuit  550  to work is when the filtered signal&#39;s voltage approaches (and is still higher than) the minimum conduction voltage. 
     It&#39;s worth noting that anti-flickering circuit  550  may be more suitable for the situation in which LED lighting module  530  doesn&#39;t include driving circuit, for example, when LED module  630  of LED lighting module  530  is (directly) driven to emit light by a filtered signal from a filtering circuit. In this case, the light emission of LED module  630  will directly reflect variation in the filtered signal due to its ripples. In this situation, the introduction of anti-flickering circuit  550  will prevent the flickering phenomenon from occurring in the LED lamp upon the breakoff of power supply to the LED lamp. 
       FIG. 32B  is a schematic diagram of the anti-flickering circuit according to an embodiment of the present invention. Referring to  FIG. 32B , anti-flickering circuit  650  includes at least a resistor, such as two resistors connected in series between filtering output terminals  521  and  522 . In this embodiment, anti-flickering circuit  650  in use consumes partial energy of a filtered signal continually. When in normal operation of the LED lamp, this partial energy is far lower than the energy consumed by LED lighting module  530 . But upon a breakoff or stop of the power supply, when the voltage level of the filtered signal decreases to approach the minimum conduction voltage of LED module  630 , this partial energy is still consumed by anti-flickering circuit  650  in order to offset the impact of the resonant signals which may cause the flickering of light emission of LED module  630 . In some embodiments, a current equal to or larger than an anti-flickering current level may be set to flow through anti-flickering circuit  650  when LED module  630  is supplied by the minimum conduction voltage, and then an equivalent anti-flickering resistance of anti-flickering circuit  650  can be determined based on the set current. 
       FIG. 33A  is a block diagram of a power supply module in an LED tube lamp according to an embodiment of the present invention. Compared to that shown in  FIG. 28E , the present embodiment comprises the rectifying circuits  510  and  540 , and the filtering circuit  520 , and further comprises two filament-simulating circuits  1560 . The filament-simulating circuits  1560  are respectively coupled between the pins  501  and  502  and coupled between the pins  503  and  504 , for improving a compatibility with a lamp driving circuit having filament detection function, e.g.: program-start ballast. 
     In an initial stage upon the lamp driving circuit having filament detection function being activated, the lamp driving circuit will determine whether the filaments of the lamp operate normally or are in an abnormal condition of short-circuit or open-circuit. When determining the abnormal condition of the filaments, the lamp driving circuit stops operating and enters a protection state. In order to avoid that the lamp driving circuit erroneously determines the LED tube lamp to be abnormal due to the LED tube lamp having no filament, the two filament-simulating circuits  1560  simulate the operation of actual filaments of a fluorescent tube to have the lamp driving circuit enter into a normal state to start the LED lamp normally. 
       FIG. 33B  is a schematic diagram of a filament-simulating circuit according to an embodiment of the present invention. The filament-simulating circuit comprises a capacitor  1663  and a resistor  1665  connected in parallel, and two ends of the capacitor  1663  and two ends of the resistor  1665  are re respectively coupled to filament simulating terminals  1661  and  1662 . Referring to  FIG. 33A , the filament simulating terminals  1661  and  1662  of the two filament simulating  1660  are respectively coupled to the pins  501  and  502  and the pins  503  and  504 . During the filament detection process, the lamp driving circuit outputs a detection signal to detect the state of the filaments. The detection signal passes the capacitor  1663  and the resistor  1665  and so the lamp driving circuit determines that the filaments of the LED lamp are normal. 
     In addition, a capacitance value of the capacitor  1663  is low and so a capacitive reactance (equivalent impedance) of the capacitor  1663  is far lower than an impedance of the resistor  1665  due to the lamp driving circuit outputting a high-frequency alternative current (AC) signal to drive LED lamp. Therefore, the filament-simulating circuit  1660  consumes fairly low power when the LED lamp operates normally, and so it almost does not affect the luminous efficiency of the LED lamp. 
       FIG. 33C  is a schematic block diagram including a filament-simulating circuit according to an embodiment of the present invention. In the present embodiment, the filament-simulating circuit  1660  replaces the terminal adapter circuit  541  of the rectifying circuit  810  shown in  FIG. 29C , which is adopted as the rectifying circuit  510  or/and  540  in the LED lamp. For example, the filament-simulating circuit  1660  of the present embodiment has both of filament simulating and terminal adapting functions. Referring to  FIG. 33A , the filament simulating terminals  1661  and  1662  of the filament-simulating circuit  1660  are respectively coupled to the pins  501  and  502  or/and pins  503  and  504 . The half-wave node  819  of rectifying unit  815  in the rectifying circuit  810  is coupled to the filament simulating terminal  1662 . 
       FIG. 33D  is a schematic block diagram including a filament-simulating circuit according to another embodiment of the present invention. Compared to that shown in  FIG. 33C , the half-wave node is changed to be coupled to the filament simulating terminal  1661 , and the filament-simulating circuit  1660  in the present embodiment still has both of filament simulating and terminal adapting functions. 
       FIG. 33E  is a schematic diagram of a filament-simulating circuit according to another embodiment of the present invention. A filament-simulating circuit  1760  comprises capacitors  1763  and  1764 , and the resistors  1765  and  1766 . The capacitors  1763  and  1764  are connected in series and coupled between the filament simulating terminals  1661  and  1662 . The resistors  1765  and  1766  are connected in series and coupled between the filament simulating terminals  1661  and  1662 . Furthermore, the connection node of capacitors  1763  and  1764  is coupled to that of the resistors  1765  and  1766 . Referring to  FIG. 33A , the filament simulating terminals  1661  and  1662  of the filament-simulating circuit  1760  are respectively coupled to the pins  501  and  502  and the pins  503  and  504 . When the lamp driving circuit outputs the detection signal for detecting the state of the filament, the detection signal passes the capacitors  1763  and  1764  and the resistors  1765  and  1766  so that the lamp driving circuit determines that the filaments of the LED lamp are normal. 
     It is worth noting that in some embodiments, capacitance values of the capacitors  1763  and  1764  are low and so a capacitive reactance of the serially connected capacitors  1763  and  1764  is far lower than an impedance of the serially connected resistors  1765  and  1766  due to the lamp driving circuit outputting the high-frequency AC signal to drive LED lamp. Therefore, the filament-simulating circuit  1760  consumes fairly low power when the LED lamp operates normally, and so it almost does not affect the luminous efficiency of the LED lamp. Moreover, any one of the capacitor  1763  and the resistor  1765  is short circuited or is an open circuit, or any one of the capacitor  1764  and the resistor  1766  is short circuited or is an open circuit, the detection signal still passes through the filament-simulating circuit  1760  between the filament simulating terminals  1661  and  1662 . Therefore, the filament-simulating circuit  1760  still operates normally when any one of the capacitor  1763  and the resistor  1765  is short circuited or is an open circuit or any one of the capacitor  1764  and the resistor  1766  is short circuited or is an open circuit, and so it has quite high fault tolerance. 
       FIG. 33F  is a schematic block diagram including a filament-simulating circuit according to an embodiment of the present invention. In the present embodiment, the filament-simulating circuit  1860  replaces the terminal adapter circuit  541  of the rectifying circuit  810  shown in  FIG. 29C , which is adopted as the rectifying circuit  510  or/and  540  in the LED lamp. For example, the filament-simulating circuit  1860  of the present embodiment has both of filament simulating and terminal adapting functions. An impedance of the filament-simulating circuit  1860  has a negative temperature coefficient (NTC), i.e., the impedance at a higher temperature is lower than that at a lower temperature. In the present embodiment, the filament-simulating circuit  1860  comprises two NTC resistors  1863  and  1864  connected in series and coupled to the filament simulating terminals  1661  and  1662 . Referring to  FIG. 33A , the filament simulating terminals  1661  and  1662  are respectively coupled to the pins  501  and  502  or/and the pins  503  and  504 . The half-wave node  819  of the rectifying unit  815  in the rectifying circuit  810  is coupled to a connection node of the NTC resistors  1863  and  1864 . 
     When the lamp driving circuit outputs the detection signal for detecting the state of the filament, the detection signal passes the NTC resistors  1863  and  1864  so that the lamp driving circuit determines that the filaments of the LED lamp are normal. The impedance of the serially connected NTC resistors  1863  and  1864  is gradually decreased with the gradually increasing of temperature due to the detection signal or a preheat process. When the lamp driving circuit enters into the normal state to start the LED lamp normally, the impedance of the serially connected NTC resistors  1863  and  1864  is decreased to a relative low value and so the power consumption of the filament simulation circuit  1860  is lower. 
     An exemplary impedance of the filament-simulating circuit  1860  can be 10 ohms or more at room temperature (25 degrees Celsius) and may be decreased to a range of about 2-10 ohms when the lamp driving circuit enters into the normal state. It may be preferred that the impedance of the filament-simulating circuit  1860  is decreased to a range of about 3-6 ohms when the lamp driving circuit enters into the normal state. 
       FIG. 34A  is a block diagram of a power supply module in an LED tube lamp according to an embodiment of the present invention. Compared to that shown in  FIG. 28E , the present embodiment comprises the rectifying circuits  510  and  540 , and the filtering circuit  520 , and further comprises an over voltage protection (OVP) circuit  1570 . The OVP circuit  1570  is coupled to the filtering output terminals  521  and  522  for detecting the filtered signal. The OVP circuit  1570  clamps the level of the filtered signal when determining the level thereof higher than a defined OVP value. Hence, the OVP circuit  1570  protects the LED lighting module  530  from damage due to an OVP condition. The rectifying circuit  540  may be omitted and is therefore depicted by a dotted line. 
       FIG. 34B  is a schematic diagram of an overvoltage protection (OVP) circuit according to an embodiment of the present invention. The OVP circuit  1670  comprises a voltage clamping diode  1671 , such as zener diode, coupled to the filtering output terminals  521  and  522 . The voltage clamping diode  1671  is conducted to clamp a voltage difference at a breakdown voltage when the voltage difference of the filtering output terminals  521  and  522  (i.e., the level of the filtered signal) reaches the breakdown voltage. The breakdown voltage may be preferred in a range of about 40 V to about 100 V, and more preferred in a range of about 55 V to about 75V. Referring to  FIG. 24 , in one embodiment, each of the LED light sources  202  may be provided with a LED lead frame  202   b  having a recess  202   a , and an LED chip  18  disposed in the recess  202   a . The recess  202   a  may be one or more than one in amount. The recess  202   a  may be filled with phosphor covering the LED chip  18  to convert emitted light therefrom into a desired light color. Compared with a conventional LED chip being a substantial square, the LED chip  18  in this embodiment is in some embodiments rectangular with the dimension of the length side to the width side at a ratio ranges generally from about 2:1 to about 10:1, in some embodiments from about 2.5:1 to about 5:1, and in some more desirable embodiments from 3:1 to 4.5:1. Moreover, the LED chip  18  is in some embodiments arranged with its length direction extending along the length direction of the glass tube  1  to increase the average current density of the LED chip  18  and improve the overall illumination field shape of the glass tube  1 . The glass tube  1  may have a number of LED light sources  202  arranged into one or more rows, and each row of the LED light sources  202  is arranged along the length direction (Y-direction) of the glass tube  1 . 
     Referring again to  FIG. 24 , the recess  202   a  is enclosed by two parallel first sidewalls  15  and two parallel second sidewalls  16  with the first sidewalls  15  being lower than the second sidewalls  16 . The two first sidewalls  15  are arranged to be located along a length direction (Y-direction) of the glass tube  1  and extend along the width direction (X-direction) of the glass tube  1 , and two second sidewalls  16  are arranged to be located along a width direction (X-direction) of the glass tube  1  and extend along the length direction (Y-direction) of the glass tube  1 . The extending direction of the first sidewalls  15  is required to be substantially rather than exactly parallel to the width direction (X-direction) of the glass tube  1 , and the first sidewalls may have various outlines such as zigzag, curved, wavy, and the like. Similarly, the extending direction of the second sidewalls  16  is required to be substantially rather than exactly parallel to the length direction (Y-direction) of the glass tube  1 , and the second sidewalls may have various outlines such as zigzag, curved, wavy, and the like. In one row of the LED light sources  202 , the arrangement of the first sidewalls  15  and the second sidewalls  16  for each LED light source  202  can be same or different. 
     Having the first sidewalls  15  being lower than the second sidewalls  16  and proper distance arrangement, the LED lead frame  202   b  allows dispersion of the light illumination to cross over the LED lead frame  202   b  without causing uncomfortable visual feeling to people observing the LED tube lamp along the Y-direction. The first sidewalls  15  may to be lower than the second sidewalls, however, and in this case each rows of the LED light sources  202  are more closely arranged to reduce grainy effects. On the other hand, when a user of the LED tube lamp observes the glass tube thereof along the X-direction, the second sidewalls  16  also can block user&#39;s line of sight from seeing the LED light sources  202 , and which reduces unpleasing grainy effects. 
     Referring again to  FIG. 24 , the first sidewalls  15  each includes an inner surface  15   a  facing toward outside of the recess  202   a . The inner surface  15   a  may be designed to be an inclined plane such that the light illumination easily crosses over the first sidewalls  15  and spreads out. The inclined plane of the inner surface  15   a  may be flat or cambered or combined shape. When the inclined plane is flat, the slope of the inner surface  15   a  ranges from about 30 degrees to about 60 degrees. Thus, an included angle between the bottom surface of the recess  202   a  and the inner surface  15   a  may range from about 120 to about 150 degrees. In some embodiments, the slope of the inner surface  15   a  ranges from about 15 degrees to about 75 degrees, and the included angle between the bottom surface of the recess  202   a  and the inner surface  15   a  ranges from about 105 degrees to about 165 degrees. 
     There may be one row or several rows of the LED light sources  202  arranged in a length direction (Y-direction) of the glass tube  1 . In case of one row, in one embodiment the second sidewalls  16  of the LED lead frames  202   b  of all of the LED light sources  202  located in the same row are disposed in same straight lines to respectively from two walls for blocking user&#39;s line of sight seeing the LED light sources  202 . In case of several rows, in one embodiment only the LED lead frames  202   b  of the LED light sources  202  disposed in the outermost two rows are disposed in same straight lines to respectively form walls for blocking user&#39;s line of sight seeing the LED light sources  202 . The LED lead frames  202   b  of the LED light sources  202  disposed in the other rows can have different arrangements. For example, as far as the LED light sources  202  located in the middle row (third row) are concerned, the LED lead frames  202   b  thereof may be arranged such that: each LED lead frame  202   b  has the first sidewalls  15  arranged along the length direction (Y-direction) of the glass tube  1  with the second sidewalls  16  arranged along in the width direction (X-direction) of the glass tube  1 ; each LED lead frame  202   b  has the first sidewalls  15  arranged along the width direction (X-direction) of the glass tube  1  with the second sidewalls  16  arranged along the length direction (Y-direction) of the glass tube  1 ; or the LED lead frames  202   b  are arranged in a staggered manner. To reduce grainy effects caused by the LED light sources  202  when a user of the LED tube lamp observes the glass tube thereof along the X-direction, it may be enough to have the second sidewalls  16  of the LED lead frames  202   b  of the LED light sources  202  located in the outmost rows to block user&#39;s line of sight from seeing the LED light sources  202 . Different arrangement may be used for the second sidewalls  16  of the LED lead frames  202   b  of one or several of the LED light sources  202  located in the outmost two rows. 
     In summary, when a plurality of the LED light sources  202  are arranged in a row extending along the length direction of the glass tube  1 , the second sidewalls  16  of the LED lead frames  202   b  of all of the LED light sources  202  located in the same row may be disposed in same straight lines to respectively form walls for blocking user&#39;s line of sight seeing the LED light sources  202 . When a plurality of the LED light sources  202  are arranged in a number of rows being located along the width direction of the glass tube  1  and extending along the length direction of the glass tube  1 , the second sidewalls  16  of the LED lead frames  202   b  of all of the LED light sources  202  located in the outmost two rows may be disposed in straight lines to respectively from two walls for blocking user&#39;s line of sight seeing the LED light sources  202 . The one or more than one rows located between the outmost rows may have the first sidewalls  15  and the second sidewalls  16  arranged in a way the same as or different from that for the outmost rows. 
     Turing to  FIG. 27 , in accordance with an exemplary embodiment of the claimed invention, the end cap  3  includes a housing, an electrically conductive pin  301 , a power supply  5  and a safety switch. The safety switch is positioned between the electrically conductive pin  301  and the power supply  5 . The safety switch may further include a micro switch  334  and an actuator  332 . The end caps  3  are disposed on two ends of the glass tube  1  and configured to turn on the safety switch—and make a circuit connecting, sequentially, mains electricity coming from a socket of a lamp holder, the electrically conductive pin  301 , the power supply  5  and the LED light assembly—when the electrically conductive pin  301  is plugged into the socket. The end cap  3  is configured to turn off the safety switch and open the circuit when the electrically conductive pin  301  is unplugged from the socket of the lamp holder. The glass tube  1  is thus configured to minimize risk of electric shocks during installation and to comply with safety regulations. 
     In some embodiments, the safety switch directly—and mechanically—makes and breaks the circuit of the LED tube lamp. In other embodiments, the safe switch controls another electrical circuit, i.e. a relay, which in turn makes and breaks the circuit of the LED tube lamp. Some relays use an electromagnet to operate a switching mechanism mechanically, but other operating principles are also used. For example, solid-state relays control power circuits with no moving parts, instead using a semiconductor device to perform switching. 
     As shown in  FIG. 27 , the proportion of the end cap  3  in relation to the glass tube  1  is exaggerated in order to highlight the structure of the end cap  3 . In an embodiment, the depth of the end cap  3  is from 9 to 70 mm. The axial length of the glass tube  1  is from 254 to 2000 mm, i.e. from 1 inch to 8 inch. 
     The safety switch may be two in number and disposed respectively inside two end caps. In an embodiment, a first end cap of the lamp tube includes a safety switch but a second end cap does not, and a warning is attached to the first end cap to alert an operator to plug in the second end cap before moving on to the first end cap. 
     In an embodiment, the safety switch may be a level switch including liquid. Only when liquid inside the level switch is made to flow to a designated place, the level switch is turned on. The end cap  3  is configured to turn on the level switch and, directly or through a relay, make the circuit only when the electrically conductive pin  301  is plugged into the socket. Alternatively, the micro switch  334  is triggered by the actuator  332  when the electrically conductive pin  301  is plugged into the socket and the actuator  332  is pressed. The end cap  3  is configured to, likewise, turn on the micro switch  334  and, directly or through a relay, make the circuit only when the electrically conductive pin  301  is plugged into the socket. 
     Turning to  FIG. 26A , in accordance with an exemplary embodiment of the claimed invention, the end cap  3  includes a housing  300 , an electrically conductive pin  301  disposed on top wall of the housing  300 , an actuator  332  movably disposed on the housing  300  along the direction of the electrically conductive pin  301 , and a micro switch  334 . The upper portion of the actuator  332  projects out of an opening formed in the top wall of the housing  300 . The actuator  332  includes, inside the housing  300 , a stopping flange  337  extending radially from its intermediary portion and a shaft  335  extending axially in its lower portion. The shaft  335  is movably connected to a base  336  rigidly mounted inside the housing  300 . A preloaded coil spring  333  is retained, around the shaft  335 , between the stopping flange  337  and the base  336 . An aperture is provided in the upper portion of the actuator  332  through which the electrically conductive pin  301  is arranged. The micro switch  334  is positioned inside the housing  300  to be actuated by the shaft  335  at a predetermined actuation point. The micro switch  334 , when actuated, makes the circuit, directly or through a relay, between the electrically conductive pin  301  and the power supply  5 . The actuator  332  is aligned with the electrically conductive pin  301 , the opening in the top wall of the housing  300  and the coil spring  333  along the longitudinal axis of the glass tube  1  to be reciprocally movable between the top wall of the housing  300  and the base  336 . When the electrically conductive pin  301  is unplugged from the socket of a lamp holder, the coil spring  333  and stopping flange  337  biases the actuator  332  to its rest position. The micro switch  334  stays off and the circuit of the LED tube lamp stays open. When the electrically conductive pin  301  is duly plugged into the socket, the actuator  332  is depressed and brings the shaft  335  to the actuation point. The micro switch  334  is turned on to, directly or through a relay, complete the circuit of the LED tube lamp. 
     Turning to  FIG. 26B , in accordance with an exemplary embodiment of the claimed invention, the end cap  3  includes a housing  300 , an electrically conductive pin  301   a  disposed on top wall of the housing  300 , an actuator  332  movably disposed on the housing  300  along the direction of the electrically conductive pin  301   a , and a micro switch  334 . In an embodiment, the electrically conductive pin  301   a  is an enlarged hollow structure. The upper portion of the actuator  332  is bowl-shaped to receive the electrically conductive pin  301   a  and projects out of an opening formed in the top wall of the housing  300 . The actuator  332  includes, inside the housing  300 , a stopping flange  337  extending radially from its intermediary portion and, in its lower portion, a spring retainer and a bulging part  338 . A preloaded coil spring  333  is retained between the string retainer and a base  336  rigidly mounted inside the housing  300 . The micro switch  334  is positioned inside the housing  300  to be actuated by the bulging part  338  at a predetermined actuation point. The micro switch  334 , when actuated, makes the circuit, directly or through a relay, between the electrically conductive pin  301   a  and the power supply. The actuator  332  is aligned with the electrically conductive pin  301   a , the opening in the top wall of the housing  300  and the coil spring  333  along the longitudinal axis of the lamp tube  1  to be reciprocally movable between the top wall of the housing  300  and the base  336 . When the electrically conductive pin  301   a  is unplugged from the socket of a lamp holder, the coil spring  333  and the stopping flange  337  biases the actuator  332  to its rest position. The micro switch  334  stays off and the circuit of the LED tube lamp  1  stays open. When the electrically conductive pin  301   a  is duly plugged into the socket of the lamp holder, the actuator  332  is depressed and brings the bulging part  338  to the actuation point. The micro switch  334  is turned on to, directly or through a relay, complete the circuit. 
     Turning to  FIG. 26C , in accordance with an exemplary embodiment of the claimed invention, the end cap  3  includes a housing  300 , a power supply (not shown), an electrically conductive pin  301  disposed on top wall of the housing  300 , an actuator  332  movably disposed on the housing  300  along the direction of the electrically conductive pin  301 , and a micro switch  334 . In an embodiment, the end cap includes a pair of electrically conductive pins  301 . The upper portion of the actuator  332  projects out of an opening formed in the top wall of the housing  300 . The actuator  332  includes, inside the housing  300 , a stopping flange  337  extending radially from its intermediary portion and a spring retainer in its lower portion. A first coil spring  333   a , preloaded, is retained between the string retainer and a first end of the micro switch  334 . A second coil spring  333   b , also preloaded, is retained between a second end of the micro switch  334  and a base rigidly mounted inside the housing. Both of the springs  333   a ,  333   b  are chosen to respond to a gentle depression; however, the first coil spring  333   a  is chosen to have a different stiffness than the second coil spring  333   b . Preferably, the first coil spring  333   a  reacts to a depression of from 0.5 to 1 N but the second coil spring  333   b  reacts to a depression of from 3 to 4 N. The actuator  332  is aligned with the opening in the top wall of the housing  300 , the micro switch  334  and the set of coil springs  333   a ,  333   b  along the longitudinal axis of the lamp tube to be reciprocally movable between the top wall of the housing  300  and the base. The micro switch  334 , sandwiched between the first coil spring  333   a  and the second coil spring  333   b , is actuated when the first coil spring  333   a  is compressed to a predetermined actuation point. The micro switch  334 , when actuated, makes the circuit, directly or through a relay, between the pair of electrically conductive pins  301  and the power supply. When the pair of electrically conductive pins  301  are unplugged from the socket of a lamp holder, the pair of coil springs  333   a ,  333   b  and the stopping flange  337  bias the actuator  332  to its rest position. The micro switch  334  stays off and the circuit of the LED tube lamp stays open. When the pair of electrically conductive pins  301  are duly plugged into the socket of a lamp holder, the actuator  332  is depressed and compresses the first coil spring  333   a  to the actuation point. The micro switch  334  is turned on to, directly or through a relay, complete the circuit. 
     Turning to  FIG. 26D , in accordance with an exemplary embodiment of the claimed invention, the end cap  3  includes a housing  300 , a power supply (not shown), an electrically conductive pin  301  disposed on top wall of the housing  300 , an actuator  332  movably disposed on the housing  300  along the direction of the electrically conductive pin  301 , a first contact element  334   a  and a second contact element  338 . The upper portion of the actuator  332  projects out of an opening formed in the top wall of the housing  300 . The actuator  332  includes, inside the housing  300 , a stopping flange extending radially from its intermediary portion and a shaft  335  extending axially in its lower portion. The shaft  335  is movably connected to a base  336  rigidly mounted inside the housing  300 . A preloaded coil spring  333  is retained, around the shaft  335 , between the stopping flange and the base  336 . An aperture is provided in the upper portion of the actuator  332  through which the electrically conductive pin  301  is arranged. The actuator  332  is aligned with the electrically conductive pin  301 , the opening in the top wall of the housing  300 , the coil spring  333  and the first and second contact elements  334   a ,  338  along the longitudinal axis of the lamp tube to be reciprocally movable between the top wall of the housing  300  and the base  336 . The first contact element  334   a  includes a plurality of metallic pieces, which are spaced apart from one another, and is configured to form a flexible female-type receptacle, e.g. V-shaped or bell-shaped. The second contact element  338  is positioned on the shaft  335  to, when the shaft  335  moves downwards, come into the first contact element  334   a  and electrically connect the plurality of metallic pieces at a predetermined actuation point. The first contact element  334   a  is configured to impart a spring-like bias on the second contact element  338  when the second contact element  338  goes into the first contact element  334   a  to ensure faithful electrically conductive with one another. The first and second contact elements  334   a ,  338  are made from, preferably, copper alloy. When the electrically conductive pin  301  is unplugged from the socket of a lamp holder, the coil spring  333  and the stopping flange biases the actuator  332  to its rest position. The first and second contact elements  334   a ,  338  stay unconnected and the circuit of the LED tube lamp stays open. When the electrically conductive pin  301  is duly plugged into the socket of a lamp holder, the actuator  332  is depressed and brings the second contact element  338  to the actuation point. The first and second contact elements  334   a ,  338  are connected to, directly or through a relay, complete the circuit of the LED tube lamp. The contact element  334   a  may be made of copper. 
     Turning to  FIG. 26E , in accordance with an exemplary embodiment of the claimed invention, the end cap  3  includes a housing  300 , a power supply  5 , an electrically conductive pin  301  disposed on top wall of the housing  300 , an actuator  332  movably disposed on the housing  300  along the direction of the electrically conductive pin  301 , a first contact element  334   a  and a second contact element. The upper portion of the actuator  332  projects out of an opening formed in the top wall of the housing  300 . The actuator  332  includes, inside the housing  300 , a stopping flange extending radially from its intermediary portion and a shaft  335  extending axially in its lower portion. The shaft  335  is movably connected to a base rigidly mounted inside the housing  300 . A preloaded coil spring  333  is retained, around the shaft  335 , between the stopping flange and the base. The actuator  332  is aligned with the opening in the top wall of the housing  300 , the coil spring  333 , the first contact element  334   a  and the second contact element along the longitudinal axis of the lamp tube to be reciprocally movable between the top wall of the housing  300  and the base. The first contact element  334   a  forms an integral and flexible female-type receptacle and may be made from, preferably, copper and/or copper alloy. The second contact element, made from, preferably, copper and/or copper alloy, is fixedly disposed inside the housing  300 . In an embodiment, the second contact element is fixedly disposed on the power supply  5 . The first contact element  334   a  is attached to the lower end of the shaft  335  to, when the shaft  335  moves downwards, receive and electrically connect the second contact element at a predetermined actuation point. The first contact element  334   a  is configured to impart a spring-like bias on the second contact element when the former receives the latter to ensure faithful electrically conductive with each other. When the electrically conductive pin  301  is unplugged from the socket of a lamp holder, the coil spring  333  and the stopping flange biases the actuator  332  to its rest position. The first contact element  334   a  and the second contact element stay unconnected and the circuit of the LED tube lamp stays open. When the electrically conductive pin  301  is duly plugged into the socket of a lamp holder, the actuator  332  is depressed and brings the first contact element  334   a  to the actuation point. The first contact element  334   a  and the second contact element are connected to, directly or through a relay, complete the circuit of the LED tube lamp. 
     Turning to  FIG. 26F , in accordance with an exemplary embodiment of the claimed invention, the end cap  3  includes a housing  300 , a power supply  5 , an electrically conductive pin  301  disposed on top wall of the housing  300 , an actuator  332  movably disposed on the housing  300  along the direction of the electrically conductive pin  301 , a first contact element  334   b  and a second contact element. The upper portion of the actuator  332  projects out of an opening formed in the top wall of the housing  300 . The actuator  332  includes, inside the housing  300 , a stopping flange extending radially from its intermediary portion and a shaft  335  extending axially in its lower portion. The shaft  335  is movably connected to a base rigidly mounted inside the housing  300 . A preloaded coil spring  333  is retained, around the shaft  335 , between the stopping flange and the base. The actuator  332  is aligned with the opening in the top wall of the housing  300 , the coil spring  333 , the first contact element  334   b  and the second contact element along the longitudinal axis of the lamp tube to be reciprocally movable between the top wall of the housing  300  and the base. The shaft  335  includes a non-electrically conductive body in the shape of an elongated thin plank and a window  339  carved out from the body. The first contact element  334   b  and the second contact element are fixedly disposed inside the housing  300  and face each other through the shaft  335 . The first contact element  334   b  is configured to impart a spring-like bias on the shaft  335  and to urge the shaft  335  against the second contact element. In an embodiment, the first contact element  334   b  is a bow-shaped laminate bending towards the shaft  335  and the second contact element, which is disposed on the power supply  5 . The first contact element  334   b  and the second contact element are made from, preferably, copper and/or copper alloy. When the actuator  332  is in its rest position, the first contact element  334   b  and the second contact element are prevented by the body of the shaft  335  from engaging each other. However, the first contact element  334   b  is configured to, when the shaft brings its window  339  downwards to a predetermined actuation point, engage and electrically connect the second contact element through the window  339 . When the electrically conductive pin  301  is unplugged from the socket, the coil spring  333  and the stopping flange biases the actuator  332  to its rest position. The first contact element  334   b  and the second contact element stay unconnected and the circuit of the LED tube lamp stays open. When the electrically conductive pin  301  is duly plugged into the socket of a lamp holder, the actuator  332  is depressed and brings the window  339  to the actuation point. The first contact element  334   b  engages the second contact element to, directly or through a relay, complete the circuit of the LED tube lamp. 
     In an embodiment, the upper portion of the actuator  332  that projects out of the housing  300  has a less length than the electrically conductive pin  301 . Preferably, the projected portion of the actuator  332  has a length of from 20 to 95% of that of the electrically conductive pin  301 . 
       FIG. 35A  is a block diagram of a power supply module in an LED lamp according to an embodiment of the present invention. Compared to  FIG. 28E , the embodiment of  FIG. 35A  includes rectifying circuits  510  and  540 , a filtering circuit  520 , and an LED driving module  530 , and further includes a ballast-compatible circuit  1510 . The ballast-compatible circuit  1510  may be coupled between pin  501  and/or pin  502  and rectifying circuit  510 . This embodiment is explained assuming the ballast-compatible circuit  1510  to be coupled between pin  501  and rectifying circuit  510 . With reference to  FIGS. 28A, 28B, and 28D  in addition to  FIG. 35A , lamp driving circuit  505  comprises a ballast configured to provide an AC driving signal to drive the LED lamp in this embodiment. 
     In an initial stage upon the activation of the driving system of lamp driving circuit  505 , lamp driving circuit  505 &#39;s ability to output relevant signal(s) has not risen to a standard state. However, in the initial stage the power supply module of the LED lamp instantly or rapidly receives or conducts the AC driving signal provided by lamp driving circuit  505 , which initial conduction is likely to fail the starting of the LED lamp by lamp driving circuit  505  as lamp driving circuit  505  is initially loaded by the LED lamp in this stage. For example, internal components of lamp driving circuit  505  may need to retrieve power from a transformed output in lamp driving circuit  505 , in order to maintain their operation upon the activation. In this case, the activation of lamp driving circuit  505  may end up failing as its output voltage could not normally rise to a required level in this initial stage; or the quality factor (Q) of a resonant circuit in lamp driving circuit  505  may vary as a result of the initial loading from the LED lamp, so as to cause the failure of the activation. 
     In this embodiment, in the initial stage upon activation, ballast-compatible circuit  1510  will be in an open-circuit state, preventing the energy of the AC driving signal from reaching the LED module. After a defined delay upon the AC driving signal as an external driving signal being input to the LED tube lamp, ballast-compatible circuit  1510  switches from a cutoff state during the delay to a conducting state, allowing the energy of the AC driving signal to start to reach the LED module. By means of the delayed conduction of ballast-compatible circuit  1510 , operation of the LED lamp simulates the lamp-starting characteristics of a fluorescent lamp, that is, internal gases of the fluorescent lamp will normally discharge for light emission after a delay upon activation of a driving power supply. Therefore, ballast-compatible circuit  1510  further improves the compatibility of the LED lamp with lamp driving circuits  505  such as an electronic ballast. 
     In this embodiment, rectifying circuit  540  may be omitted and is therefore depicted by a dotted line in  FIG. 35A . 
       FIG. 35B  is a block diagram of a power supply module in an LED lamp according to an embodiment of the present invention. Compared to  FIG. 35A , ballast-compatible circuit  1510  in the embodiment of  FIG. 35B  is coupled between pin  503  and/or pin  504  and rectifying circuit  540 . As explained regarding ballast-compatible circuit  1510  in  FIG. 35A , ballast-compatible circuit  1510  in  FIG. 35B  performs the function of delaying the starting of the LED lamp, or causing the input of the AC driving signal to be delayed for a predefined time, in order to prevent the failure of starting by lamp driving circuits  505  such as an electronic ballast. 
     Apart from coupling ballast-compatible circuit  1510  between terminal pin(s) and rectifying circuit in the above embodiments, ballast-compatible circuit  1510  may alternatively be included within a rectifying circuit with a different structure.  FIG. 35C  illustrates an arrangement with a ballast-compatible circuit in an LED lamp according to a preferred embodiment of the present invention. Referring to  FIG. 35C , the rectifying circuit assumes the circuit structure of rectifying circuit  810  in  FIG. 29C . Rectifying circuit  810  includes rectifying unit  815  and terminal adapter circuit  541 . Rectifying unit  815  is coupled to pins  501  and  502 , terminal adapter circuit  541  is coupled to filtering output terminals  511  and  512 , and the ballast-compatible circuit  1510  in  FIG. 35C  is coupled between rectifying unit  815  and terminal adapter circuit  541 . In this case, in the initial stage upon activation of the ballast, an AC driving signal as an external driving signal is input to the LED tube lamp, where the AC driving signal can only reach rectifying unit  815 , but cannot reach other circuits such as terminal adapter circuit  541 , other internal filter circuitry, and the LED driving module. Moreover, parasitic capacitors associated with rectifying diodes  811  and  812  within rectifying unit  815  are quite small in capacitance and thus can be ignored. Accordingly, lamp driving circuit  505  in the initial stage isn&#39;t loaded with or effectively connected to the equivalent capacitor or inductor of the power supply module of the LED lamp, and the quality factor (Q) of lamp driving circuit  505  is therefore not adversely affected in this stage, resulting in a successful starting of the LED lamp by lamp driving circuit  505 . 
     It&#39;s worth noting that under the condition that terminal adapter circuit  541  doesn&#39;t include components such as capacitors or inductors, interchanging rectifying unit  815  and terminal adapter circuit  541  in position, meaning rectifying unit  815  is connected to filtering output terminals  511  and  512  and terminal adapter circuit  541  is connected to pins  501  and  502 , doesn&#39;t affect or alter the function of ballast-compatible circuit  1510 . 
     Further, as explained in  FIGS. 29A-29D , when a rectifying circuit is connected to pins  503  and  504  instead of pins  501  and  502 , this rectifying circuit may constitute the rectifying circuit  540 . That is, the circuit arrangement with a ballast-compatible circuit  1510  in  FIG. 35C  may be alternatively included in rectifying circuit  540  instead of rectifying circuit  810 , without affecting the function of ballast-compatible circuit  1510 . 
     In some embodiments, as described above terminal adapter circuit  541  doesn&#39;t include components such as capacitors or inductors. Or when rectifying circuit  610  in  FIG. 29A  constitutes the rectifying circuit  510  or  540 , parasitic capacitances in the rectifying circuit  510  or  540  are quite small and thus can be ignored. These conditions contribute to not affecting the quality factor of lamp driving circuit  505 . 
       FIG. 35D  is a block diagram of a power supply module in an LED lamp according to an embodiment of the present invention. Compared to the embodiment of  FIG. 35A , ballast-compatible circuit  1510  in the embodiment of  FIG. 35D  is coupled between rectifying circuit  540  and filtering circuit  520 . Since rectifying circuit  540  also doesn&#39;t include components such as capacitors or inductors, the function of ballast-compatible circuit  1510  in the embodiment of  FIG. 35D  will not be affected. 
       FIG. 35E  is a block diagram of a power supply module in an LED lamp according to an embodiment of the present invention. Compared to the embodiment of  FIG. 35A , ballast-compatible circuit  1510  in the embodiment of  FIG. 35E  is coupled between rectifying circuit  510  and filtering circuit  520 . Similarly, since rectifying circuit  510  doesn&#39;t include components such as capacitors or inductors, the function of ballast-compatible circuit  1510  in the embodiment of  FIG. 35E  will not be affected. 
       FIG. 35F  is a schematic diagram of the ballast-compatible circuit according to an embodiment of the present invention. Referring to  FIG. 35F , a ballast-compatible circuit  1610  has an initial state in which an equivalent open-circuit is obtained at ballast-compatible circuit input and output terminals  1611  and  1621 . Upon receiving an input signal at ballast-compatible circuit input terminal  1611 , a delay will pass until a current conduction occurs through and between ballast-compatible circuit input and output terminals  1611  and  1621 , transmitting the input signal to ballast-compatible circuit output terminal  1621 . 
     Ballast-compatible circuit  1610  includes a diode  1612 , resistors  1613 ,  1615 ,  1618 ,  1620 , and  1622 , a bidirectional triode thyristor (TRIAC)  1614 , a DIAC or symmetrical trigger diode  1617 , a capacitor  1619 , and ballast-compatible circuit input and output terminals  1611  and  1621 . It&#39;s noted that the resistance of resistor  1613  should be quite large so that when bidirectional triode thyristor  1614  is cutoff in an open-circuit state, an equivalent open-circuit is obtained at ballast-compatible circuit input and output terminals  1611  and  1621 . 
     Bidirectional triode thyristor  1614  is coupled between ballast-compatible circuit input and output terminals  1611  and  1621 , and resistor  1613  is also coupled between ballast-compatible circuit input and output terminals  1611  and  1621  and in parallel to bidirectional triode thyristor  1614 . Diode  1612 , resistors  1620  and  1622 , and capacitor  1619  are series-connected in sequence between ballast-compatible circuit input and output terminals  1611  and  1621 , and are connected in parallel to bidirectional triode thyristor  1614 . Diode  1612  has an anode connected to bidirectional triode thyristor  1614 , and has a cathode connected to an end of resistor  1620 . Bidirectional triode thyristor  1614  has a control terminal connected to a terminal of symmetrical trigger diode  1617 , which has another terminal connected to an end of resistor  1618 , which has another end connected to a node connecting capacitor  1619  and resistor  1622 . Resistor  1615  is connected between the control terminal of bidirectional triode thyristor  1614  and a node connecting resistor  1613  and capacitor  1619 . 
     When an AC driving signal (such as a high-frequency high-voltage AC signal output by an electronic ballast) is initially input to ballast-compatible circuit input terminal  1611 , bidirectional triode thyristor  1614  will be in an open-circuit state, not allowing the AC driving signal to pass through and the LED lamp is therefore also in an open-circuit state. In this state, the AC driving signal is charging capacitor  1619  through diode  1612  and resistors  1620  and  1622 , gradually increasing the voltage of capacitor  1619 . Upon continually charging for a period of time, the voltage of capacitor  1619  increases to be above the trigger voltage value of symmetrical trigger diode  1617  so that symmetrical trigger diode  1617  is turned on in a conducting state. Then the conducting symmetrical trigger diode  1617  will in turn trigger bidirectional triode thyristor  1614  on in a conducting state. In this situation, the conducting bidirectional triode thyristor  1614  electrically connects ballast-compatible circuit input and output terminals  1611  and  1621 , allowing the AC driving signal to flow through ballast-compatible circuit input and output terminals  1611  and  1621 , thus starting the operation of the power supply module of the LED lamp. In this case the energy stored by capacitor  1619  will maintain the conducting state of bidirectional triode thyristor  1614 , to prevent the AC variation of the AC driving signal from causing bidirectional triode thyristor  1614  and therefore ballast-compatible circuit  1610  to be cutoff again, or to prevent the problem of bidirectional triode thyristor  1614  alternating or switching between its conducting and cutoff states. 
     In general, in hundreds of milliseconds upon activation of a lamp driving circuit  505  such as an electronic ballast, the output voltage of the ballast has risen above a certain voltage value as the output voltage hasn&#39;t been adversely affected by the sudden initial loading from the LED lamp. A detection mechanism to detect whether lighting of a fluorescent lamp is achieved may be disposed in lamp driving circuits  505  such as an electronic ballast. In this detection mechanism, if a fluorescent lamp fails to be lit up for a defined period of time, an abnormal state of the fluorescent lamp is detected, causing the fluorescent lamp to enter a protection state. In view of these facts, in certain embodiments, the delay provided by ballast-compatible circuit  1610  until conduction of ballast-compatible circuit  1610  and then the LED lamp should be and may preferably be in the range of about 0.1˜3 seconds. 
     It&#39;s worth noting that an additional capacitor  1623  may be coupled in parallel to resistor  1622 . Capacitor  1623  works to reflect or support instantaneous change in the voltage between ballast-compatible circuit input and output terminals  1611  and  1621 , and will not affect the function of delayed conduction performed by ballast-compatible circuit  1610 . 
       FIG. 35G  is a block diagram of a power supply module in an LED lamp according to an embodiment of the present invention. Compared to the embodiment of  FIG. 28D , lamp driving circuit  505  in the embodiment of  FIG. 35G  drives a plurality of LED tube lamps  500  connected in series, wherein a ballast-compatible circuit  1610  is disposed in each of the LED tube lamps  500 . For the convenience of illustration, two series-connected LED tube lamps  500  are assumed for example and explained as follows. 
     Because the two ballast-compatible circuits  1610  respectively of the two LED tube lamps  500  can actually have different delays until conduction of the LED tube lamps  500 , due to various factors such as errors occurring in production processes of some components, the actual timing of conduction of each of the ballast-compatible circuits  1610  is different. Upon activation of a lamp driving circuit  505 , the voltage of the AC driving signal provided by lamp driving circuit  505  will be shared out by the two LED tube lamps  500  roughly equally. Subsequently when only one of the two LED tube lamps  500  first enters a conducting state, the voltage of the AC driving signal then will be borne mostly or entirely by the other LED tube lamp  500 . This situation will cause the voltage across the ballast-compatible circuits  1610  in the other LED tube lamp  500  that&#39;s not conducting to suddenly increase or be doubled, meaning the voltage between ballast-compatible circuit input and output terminals  1611  and  1621  might even be suddenly doubled. In view of this, if capacitor  1623  is included, the voltage division effect between capacitors  1619  and  1623  will instantaneously increase the voltage of capacitor  1619 , making symmetrical trigger diode  1617  triggering bidirectional triode thyristor  1614  into a conducting state, thus causing the two ballast-compatible circuits  1610  respectively of the two LED tube lamps  500  to become conducting almost at the same time. Therefore, by introducing capacitor  1623 , the situation, where one of the two ballast-compatible circuits  1610  respectively of the two series-connected LED tube lamps  500  that is first conducting has its bidirectional triode thyristor  1614  then suddenly cutoff as having insufficient current passing through due to the discrepancy between the delays provided by the two ballast-compatible circuits  1610  until their respective conductions, can be avoided. Therefore, using each ballast-compatible circuit  1610  with capacitor  1623  further improves the compatibility of the series-connected LED tube lamps with each of lamp driving circuits  505  such as an electronic ballast. 
     In practical use, a suggested range of the capacitance of capacitor  1623  is about 10 pF to about 1 nF, which may preferably be in the range of about 10 pF to about 100 pF, and may be even more desirable at about 47 pF. 
     It&#39;s worth noting that diode  1612  is used or configured to rectify the signal for charging capacitor  1619 . Therefore, with reference to  FIGS. 35C, 35D, and 35E , in the case when ballast-compatible circuit  1610  is arranged following a rectifying unit or circuit, diode  1612  may be omitted. Thus, diode  1612  is depicted in a dotted line in  FIG. 35F . 
       FIG. 35H  is a schematic diagram of the ballast-compatible circuit according to another embodiment of the present invention. Referring to  FIG. 35H , a ballast-compatible circuit  1710  has an initial state in which an equivalent open-circuit is obtained at ballast-compatible circuit input and output terminals  1711  and  1721 . Upon receiving an input signal at ballast-compatible circuit input terminal  1711 , ballast-compatible circuit  1710  will be in a cutoff state when the level of the input external driving signal is below a defined value corresponding to a conduction delay of ballast-compatible circuit  1710 ; and ballast-compatible circuit  1710  will enter a conducting state upon the level of the input external driving signal reaching the defined value, thus transmitting the input signal to ballast-compatible circuit output terminal  1721 . 
     Ballast-compatible circuit  1710  includes a bidirectional triode thyristor (TRIAC)  1712 , a DIAC or symmetrical trigger diode  1713 , resistors  1714 ,  1716 , and  1717 , and a capacitor  1715 . Bidirectional triode thyristor  1712  has a first terminal connected to ballast-compatible circuit input terminal  1711 ; a control terminal connected to a terminal of symmetrical trigger diode  1713  and an end of resistor  1714 ; and a second terminal connected to another end of resistor  1714 . Capacitor  1715  has an end connected to another terminal of symmetrical trigger diode  1713 , and has another end connected to the second terminal of bidirectional triode thyristor  1712 . Resistor  1717  is in parallel connection with capacitor  1715 , and is therefore also connected to said another terminal of symmetrical trigger diode  1713  and the second terminal of bidirectional triode thyristor  1712 . And resistor  1716  has an end connected to the node connecting capacitor  1715  and symmetrical trigger diode  1713 , and has another end connected to ballast-compatible circuit output terminal  1721 . 
     When an AC driving signal (such as a high-frequency high-voltage AC signal output by an electronic ballast) is initially input to ballast-compatible circuit input terminal  1711 , bidirectional triode thyristor  1712  will be in an open-circuit state, not allowing the AC driving signal to pass through and the LED lamp is therefore also in an open-circuit state. The input of the AC driving signal causes a potential difference between ballast-compatible circuit input terminal  1711  and ballast-compatible circuit output terminal  1721 . When the AC driving signal increases with time to eventually reach a sufficient amplitude (which is a defined level after the delay) after a period of time, the signal level at ballast-compatible circuit output terminal  1721  has a reflected voltage at the control terminal of bidirectional triode thyristor  1712  after passing through resistor  1716 , parallel-connected capacitor  1715  and resistor  1717 , and resistor  1714 , wherein the reflected voltage then triggers bidirectional triode thyristor  1712  into a conducting state. This conducting state makes ballast-compatible circuit  1710  entering a conducting state which causes the LED lamp to operate normally. Upon bidirectional triode thyristor  1712  conducting, a current flows through resistor  1716  and then charges capacitor  1715  to store a specific voltage on capacitor  1715 . In this case, the energy stored by capacitor  1715  will maintain the conducting state of bidirectional triode thyristor  1712 , to prevent the AC variation of the AC driving signal from causing bidirectional triode thyristor  1712  and therefore ballast-compatible circuit  1710  to be cutoff again, or to prevent the situation of bidirectional triode thyristor  1712  alternating or switching between its conducting and cutoff states. 
       FIG. 35I  illustrates the ballast-compatible circuit according to an embodiment of the present invention. Referring to  FIG. 35I , a ballast-compatible circuit  1810  includes a housing  1812 , a metallic electrode  1813 , a bimetallic strip  1814 , and a heating filament  1816 . Metallic electrode  1813  and heating filament  1816  protrude from the housing  1812 , so that they each have a portion inside the housing  1812  and a portion outside of the housing  1812 . Metallic electrode  1813 &#39;s outside portion has a ballast-compatible circuit input terminal  1811 , and heating filament  1816 &#39;s outside portion has a ballast-compatible circuit output terminal  1821 . Housing  1812  is hermetic or tightly sealed and contains inertial gas  1815  such as helium gas. Bimetallic strip  1814  is inside housing  1812  and is physically and electrically connected to the portion of heating filament  1816  that is inside the housing  1812 . And there is a spacing between bimetallic strip  1814  and metallic electrode  1813 , so that ballast-compatible circuit input terminal  1811  and ballast-compatible circuit output terminal  1821  are not electrically connected in the initial state of ballast-compatible circuit  1810 . Bimetallic strip  1814  may include two metallic strips with different temperature coefficients, wherein the metallic strip closer to metallic electrode  1813  has a smaller temperature coefficient, and the metallic strip more away from metallic electrode  1813  has a larger temperature coefficient. 
     When an AC driving signal (such as a high-frequency high-voltage AC signal output by an electronic ballast) is initially input at ballast-compatible circuit input terminal  1811  and ballast-compatible circuit output terminal  1821 , a potential difference between metallic electrode  1813  and heating filament  1816  is formed. When the potential difference increases enough to cause electric arc or arc discharge through inertial gas  1815 , meaning when the AC driving signal increases with time to eventually reach the defined level after a delay, then inertial gas  1815  is then heated to cause bimetallic strip  1814  to swell toward metallic electrode  1813  (as in the direction of the broken-line arrow in  FIG. 35I ), with this swelling eventually causing bimetallic strip  1814  to bear against metallic electrode  1813 , forming the physical and electrical connections between them. In this situation, there is electrical conduction between ballast-compatible circuit input terminal  1811  and ballast-compatible circuit output terminal  1821 . Then the AC driving signal flows through and thus heats heating filament  1816 . In this heating process, heating filament  1816  allows a current to flow through when electrical conduction exists between metallic electrode  1813  and bimetallic strip  1814 , causing the temperature of bimetallic strip  1814  to be above a defined conduction temperature. As a result, since the respective temperature of the two metallic strips of bimetallic strip  1814  with different temperature coefficients are maintained above the defined conduction temperature, bimetallic strip  1814  will bend against or toward metallic electrode  1813 , thus maintaining or supporting the physical joining or connection between bimetallic strip  1814  and metallic electrode  1813 . 
     Therefore, upon receiving an input signal at ballast-compatible circuit input and output terminals  1811  and  1821 , a delay will pass until an electrical/current conduction occurs through and between ballast-compatible circuit input and output terminals  1811  and  1821 . 
     Therefore, an exemplary ballast-compatible circuit such as described herein may be coupled between any pin and any rectifying circuit described above in the invention, wherein the ballast-compatible circuit will be in a cutoff state in a defined delay upon an external driving signal being input to the LED tube lamp, and will enter a conducting state after the delay. Otherwise, the ballast-compatible circuit will be in a cutoff state when the level of the input external driving signal is below a defined value corresponding to a conduction delay of the ballast-compatible circuit; and ballast-compatible circuit will enter a conducting state upon the level of the input external driving signal reaching the defined value. Accordingly, the compatibility of the LED tube lamp described herein with lamp driving circuits  505  such as an electronic ballast is further improved by using such a ballast-compatible circuit. 
       FIG. 36A  is a block diagram of a power supply module in an LED tube lamp according to an embodiment of the present invention. Compared to that shown in  FIG. 33A , the present embodiment comprises the rectifying circuits  510  and  540 , the filtering circuit  520 , the LED driving module  530  and the two filament-simulating circuits  1560 , and further comprises a ballast detection circuit  1590 . The ballast detection circuit  1590  may be coupled to any one of the pins  501 ,  502 ,  503  and  504  and a corresponding rectifying circuit of the rectifying circuits  510  and  540 . In the present embodiment, the ballast detection circuit  1590  is coupled between the pin  501  and the rectifying circuit  510 . 
     The ballast detection circuit  1590  detects the AC driving signal or a signal input through the pins  501 ,  502 ,  503  and  504 , and determines whether the input signal is provided by an electric ballast based on the detected result. 
       FIG. 36B  is a block diagram of a power supply module in an LED tube lamp according to an embodiment of the present invention. Compared to that shown in  FIG. 36A , the rectifying circuit  810  shown in  FIG. 29C  replaces the rectifying circuit  510 . The ballast detection circuit  1590  is coupled between the rectifying unit  815  and the terminal adapter circuit  541 . One of the rectifying unit  815  and the terminal adapter circuit  541  is coupled to the pines  503  and  504 , and the other one is coupled to the rectifying output terminal  511  and  512 . In the present embodiment, the rectifying unit  815  is coupled to the pins  503  and  504 , and the terminal adapter circuit  541  is coupled to the rectifying output terminal  511  and  512 . Similarly, the ballast detection circuit  1590  detects the signal input through the pins  503  and  504  for determining the input signal whether provided by an electric ballast according to the frequency of the input signal. 
     In addition, the rectifying circuit  810  may replace the rectifying circuit  510  instead of the rectifying circuit  540 , and the ballast detection circuit  1590  is coupled between the rectifying unit  815  and the terminal adapter circuit  541  in the rectifying circuit  510 . 
       FIG. 36C  is a block diagram of a ballast detection circuit according to an embodiment of the present invention. The ballast detection circuit  1590  comprises a detection circuit  1590   a  and a switch circuit  1590   b . The switch circuit  1590   b  is coupled to switch terminals  1591  and  1592 . The detection circuit  1590   a  is coupled to the detection terminals  1593  and  1594  for detecting a signal transmitted through the detection terminals  1593  and  1594 . Alternatively, the switch terminals  1591  and  1592  serves as the detection terminals and the detection terminals  1593  and  1594  are omitted. For example, in certain embodiments, the switch circuit  1590   b  and the detection circuit  1590   a  are commonly coupled to the switch terminals  1591  and  1592 , and the detection circuit  1590   a  detects a signal transmitted through the switch terminals  1591  and  1592 . Hence, the detection terminals  1593  and  1594  are depicted by dotted lines. 
       FIG. 36D  is a schematic diagram of a ballast detection circuit according to an embodiment of the present invention. The ballast detection circuit  1690  comprises a detection circuit  1690   a  and a switch circuit  1690   b , and is coupled between the switch terminals  1591  and  1592 . The detection circuit  1690   a  comprises a symmetrical trigger diode  1691 , resistors  1692  and  1696  and capacitors  1693 ,  1697  and  1698 . The switch circuit  1690   b  comprises a TRIAC  1699  and an inductor  1694 . 
     The capacitor  1698  is coupled between the switch terminals  1591  and  1592  for generating a detection voltage in response to a signal transmitted through the switch terminals  1591  and  1592 . When the signal is a high frequency signal, the capacitive reactance of the capacitor  1698  is fairly low and so the detection voltage generated thereby is quite high. The resistor  1692  and the capacitor  1693  are connected in series and coupled between two ends of the capacitor  1698 . The serially connected resistor  1692  and the capacitor  1693  is used to filter the detection signal generated by the capacitor  1698  and generates a filtered detection signal at a connection node thereof. The filter function of the resistor  1692  and the capacitor  1693  is used to filter high frequency noise in the detection signal for preventing the switch circuit  1690   b  from misoperation due to the high frequency noise. The resistor  1696  and the capacitor  1697  are connected in series and coupled between two ends of the capacitor  1693 , and transmit the filtered detection signal to one end of the symmetrical trigger diode  1691 . The serially connected resistor  1696  and capacitor  1697  performs second filtering of the filtered detection signal to enhance the filter effect of the detection circuit  1690   a . Based on requirement for filtering level of different application, the capacitor  1697  may be omitted and the end of the symmetrical trigger diode  1691  is coupled to the connection node of the resistor  1692  and the capacitor  1693  through the resistor  1696 . Alternatively, both of the resistor  1696  and the capacitor  1697  are omitted and the end of the symmetrical trigger diode  1691  is directly coupled to the connection node of the resistor  1692  and the capacitor  1693 . Therefore, the resistor  1696  and the capacitor  1697  are depicted by dotted lines. The other end of the symmetrical trigger diode  1691  is coupled to a control end of the TRIAC  1699  of the switch circuit  1690   b . The symmetrical trigger diode  1691  determines whether to generate a control signal  1695  to trigger the TRIAC  1699  on according to a level of a received signal. A first end of the TRIAC  1699  is coupled to the switch terminal  1591  and a second end thereof is coupled to the switch terminal through the inductor  1694 . The inductor  1694  is used to protect the TRIAC  1699  from damage due to a situation where the signal transmitted into the switch terminals  1591  and  1592  is over a maximum rate of rise of Commutation Voltage, a peak repetitive forward (off-state) voltage or a maximum rate of change of current. 
     When the switch terminals  1591  and  1592  receive a low frequency signal or a DC signal, the detection signal generated by the capacitor  1698  is high enough to make the symmetrical trigger diode  1691  generate the control signal  1695  to trigger the TRIAC  1699  on. At this time, the switch terminals  1591  and  1592  are shorted to bypass the circuit(s) connected in parallel with the switch circuit  1690   b , such as a circuit coupled between the switch terminals  1591  and  1592 , the detection circuit  1690   a  and the capacitor  1698 . 
     In some embodiments, when the switch terminals  1591  and  1592  receive a high frequency AC signal, the detection signal generated by the capacitor  1698  is not high enough to make the symmetrical trigger diode  1691  generate the control signal  1695  to trigger the TRIAC  1699  on. At this time, the TRIAC  1699  is cut off and so the high frequency AC signal is mainly transmitted through external circuit or the detection circuit  1690   a.    
     Hence, the ballast detection circuit  1690  can determine whether the input signal is a high frequency AC signal provided by an electric ballast. If yes, the high frequency AC signal is transmitted through the external circuit or the detection circuit  1690   a ; if no, the input signal is transmitted through the switch circuit  1690   b , bypassing the external circuit and the detection circuit  1690   a.    
     It is worth noting that the capacitor  1698  may be replaced by external capacitor(s), such as at least one capacitor in the terminal adapter circuits shown in  FIG. 30A-C . Therefore, the capacitor  1698  may be omitted and be therefore depicted by a dotted line. 
       FIG. 36E  is a schematic diagram of a ballast detection circuit according to an embodiment of the present invention. The ballast detection circuit  1790  comprises a detection circuit  1790   a  and a switch circuit  1790   b . The switch circuit  1790   b  is coupled between the switch terminals  1591  and  1592 . The detection circuit  1790   a  is coupled between the detection terminals  1593  and  1594 . The detection circuit  1790   a  comprises inductors  1791  and  1792  with mutual induction, capacitor  1793  and  1796 , a resistor  1794  and a diode  1797 . The switch circuit  1790   b  comprises a switch  1799 . In the present embodiment, the switch  1799  is a P-type Depletion Mode MOSFET, which is cut off when the gate voltage is higher than a threshold voltage and conducted when the gate voltage is lower than the threshold voltage. 
     The inductor  1792  is coupled between the detection terminals  1593  and  1594  and induces a detection voltage in the inductor  1791  based on a current signal flowing through the detection terminals  1593  and  1594 . The level of the detection voltage is varied with the frequency of the current signal, and may be increased with the increasing of that frequency and reduced with the decreasing of that frequency. 
     In some embodiments, when the signal is a high frequency signal, the inductive reactance of the inductor  1792  is quite high and so the inductor  1791  induces the detection voltage with a quite high level. When the signal is a low frequency signal or a DC signal, the inductive reactance of the inductor  1792  is quite low and so the inductor  1791  induces the detection voltage with a quite high level. One end of the inductor  1791  is grounded. The serially connected capacitor  1793  and resistor  1794  is connected in parallel with the inductor  1791 . The capacitor  1793  and resistor  1794  receive the detection voltage generated by the inductor  1791  and filter a high frequency component of the detection voltage to generate a filtered detection voltage. The filtered detection voltage charges the capacitor  1796  through the diode  1797  to generate a control signal  1795 . Due to the diode  1797  providing a one-way charge for the capacitor  1796 , the level of control signal generated by the capacitor  1796  is the maximum value of the detection voltage. The capacitor  1796  is coupled to the control end of the switch  1799 . First and second ends of the switch  1799  are respectively coupled to the switch terminals  1591  and  1592 . 
     When the signal received by the detection terminal  1593  and  1594  is a low frequency signal or a DC signal, the control signal  1795  generated by the capacitor  1796  is lower than the threshold voltage of the switch  1799  and so the switch  1799  are conducted. At this time, the switch terminals  1591  and  1592  are shorted to bypass the external circuit(s) connected in parallel with the switch circuit  1790   b , such as the least one capacitor in the terminal adapter circuits show in  FIG. 30A-C . 
     When the signal received by the detection terminal  1593  and  1594  is a high frequency signal, the control signal  1795  generated by the capacitor  1796  is higher than the threshold voltage of the switch  1799  and so the switch  1799  are cut off. At this time, the high frequency signal is transmitted by the external circuit(s). 
     Hence, the ballast detection circuit  1790  can determine whether the input signal is a high frequency AC signal provided by an electric ballast. If yes, the high frequency AC signal is transmitted through the external circuit(s); if no, the input signal is transmitted through the switch circuit  1790   b , bypassing the external circuit. 
     Next, exemplary embodiments of the conduction (bypass) and cut off (not bypass) operations of the switch circuit in the ballast detection circuit of an LED lamp will be illustrated. For example, the switch terminals  1591  and  1592  are coupled to a capacitor connected in series with the LED lamp, e.g., a signal for driving the LED lamp also flows through the capacitor. The capacitor may be disposed inside the LED lamp to be connected in series with internal circuit(s) or outside the LED lamp to be connected in series with the LED lamp. Referring to  FIG. 28A, 28B , or  28 D, the AC power supply  508  provides a low voltage and low frequency AC driving signal as an external driving signal to drive the LED tube lamp  500  while the lamp driving circuit  505  does not exist. At this moment, the switch circuit of the ballast detection circuit is conducted, and so the alternative driving signal is provided to directly drive the internal circuits of the LED tube lamp  500 . When the lamp driving circuit  505  exists, the lamp driving circuit  505  provides a high voltage and high frequency AC driving signal as an external driving signal to drive the LED tube lamp  500 . At this moment, the switch circuit of the ballast detection circuit is cut off, and so the capacitor is connected in series with an equivalent capacitor of the internal circuit(s) of the LED tube lamp for forming a capacitive voltage divider network. Thereby, a division voltage applied in the internal circuit(s) of the LED tube lamp is lower than the high voltage and high frequency AC driving signal, e.g.: the division voltage is in a range of 100-270V, and so no over voltage causes the internal circuit(s) damage. Alternatively, the switch terminals  1591  and  1592  is coupled to the capacitor(s) of the terminal adapter circuit shown in  FIG. 30A  to  FIG. 30C  to have the signal flowing through the half-wave node as well as the capacitor(s), e.g., the capacitor  642  in  FIG. 30A , or the capacitor  842  in  FIG. 30C . When the high voltage and high frequency AC signal generated by the lamp driving circuit  505  is input, the switch circuit is cut off and so the capacitive voltage divider is performed; and when the low frequency AC signal of the commercial power or the direct current of battery is input, the switch circuit bypasses the capacitor(s). 
     It is worth noting that the switch circuit may have plural switch unit to have two or more switch terminal for being connected in parallel with plural capacitors, (e.g., the capacitors  645  and  645  in  FIG. 30A , the capacitors  643 ,  645  and  646  in  FIG. 30A , the capacitors  743  and  744  or/and the capacitors  745  and  746  in  FIG. 30B , the capacitors  843  and  844  in  FIG. 30C , the capacitors  845  and  846  in  FIG. 30C , the capacitors  842 ,  843  and  844  in  FIG. 30C , the capacitors  842 ,  845  and  846  in  FIG. 30C , and the capacitors  842 ,  843 ,  844 ,  845  and  846  in  FIG. 30C ) for bypassing the plural capacitor. 
       FIG. 37A  is a block diagram of the filtering circuit  520  according to an embodiment of the present invention. Rectifying circuit  510  is shown in  FIG. 37A  for illustrating its connection with other components, without intending filtering circuit  520  to include rectifying circuit  510 . Referring to  FIG. 37A , filtering circuit  520  includes a filtering unit  523  coupled to rectifying output terminals  511  and  512  to receive, and to filter out ripples of, a rectified signal from rectifying circuit  510 , thereby outputting a filtered signal whose waveform is smoother than the rectified signal. Filtering circuit  520  may further comprise another filtering unit  524  coupled between a rectifying circuit and a pin, which are for example rectifying circuit  510  and pin  501 , rectifying circuit  510  and pin  502 , rectifying circuit  540  and pin  503 , or rectifying circuit  540  and pin  504 . Filtering unit  524  is for filtering of a specific frequency, in order to filter out a specific frequency component of an external driving signal. In this embodiment of  FIG. 37A , filtering unit  524  is coupled between rectifying circuit  510  and pin  501 . Filtering circuit  520  may further comprise another filtering unit  525  coupled between one of pins  501  and  502  and a diode of rectifying circuit  510 , or between one of pins  503  and  504  and a diode of rectifying circuit  540 , for reducing or filtering out electromagnetic interference (EMI). In this embodiment, filtering unit  525  is coupled between pin  501  and a diode (not shown in  FIG. 37A ) of rectifying circuit  510 . Since filtering units  524  and  525  may be present or omitted depending on actual circumstances of their uses, they are depicted by a dotted line in  FIG. 37A . 
       FIG. 37B  is a schematic diagram of the filtering unit according to an embodiment of the present invention. Referring to  FIG. 37B , filtering unit  623  includes a capacitor  625  having an end coupled to output terminal  511  and a filtering output terminal  521  and another end coupled to output terminal  512  and a filtering output terminal  522 , and is configured to low-pass filter a rectified signal from output terminals  511  and  512 , so as to filter out high-frequency components of the rectified signal and thereby output a filtered signal at output terminals  521  and  522 . 
       FIG. 37C  is a schematic diagram of the filtering unit according to an embodiment of the present invention. Referring to  FIG. 37C , filtering unit  723  comprises a pi filter circuit including a capacitor  725 , an inductor  726 , and a capacitor  727 . As is well known, a pi filter circuit looks like the symbol π in its shape or structure. Capacitor  725  has an end connected to output terminal  511  and coupled to output terminal  521  through inductor  726 , and has another end connected to output terminals  512  and  522 . Inductor  726  is coupled between output terminals  511  and  521 . Capacitor  727  has an end connected to output terminal  521  and coupled to output terminal  511  through inductor  726 , and has another end connected to output terminals  512  and  522 . 
     As seen between output terminals  511  and  512  and output terminals  521  and  522 , filtering unit  723  compared to filtering unit  623  in  FIG. 37B  additionally has inductor  726  and capacitor  727 , which are like capacitor  725  in performing low-pass filtering. Therefore, filtering unit  723  in this embodiment compared to filtering unit  623  in  FIG. 37B  has a better ability to filter out high-frequency components to output a filtered signal with a smoother waveform. 
     Inductance values of inductor  726  in the embodiment described above are chosen in some embodiments in the range of about 10 nH to about 10 mH. And capacitance values of capacitors  625 ,  725 , and  727  in the embodiments described above are chosen in some embodiments in the range, for example, of about 100 pF to about 1 uF. 
       FIG. 37D  is a schematic diagram of the filtering unit according to an embodiment of the present invention. Referring to  FIG. 37D , filtering unit  824  includes a capacitor  825  and an inductor  828  connected in parallel. Capacitor  825  has an end coupled to pin  501 , and another end coupled to rectifying output terminal  511 , and is configured to high-pass filter an external driving signal input at pin  501 , so as to filter out low-frequency components of the external driving signal. Inductor  828  has an end coupled to pin  501  and another end coupled to rectifying output terminal  511 , and is configured to low-pass filter an external driving signal input at pin  501 , so as to filter out high-frequency components of the external driving signal. Therefore, the combination of capacitor  825  and inductor  828  works to present high impedance to an external driving signal at one or more specific frequencies. Thus, the parallel-connected capacitor and inductor work to present a peak equivalent impedance to the external driving signal at a specific frequency. 
     Through appropriately choosing a capacitance value of capacitor  825  and an inductance value of inductor  828 , a center frequency f on the high-impedance band may be set at a specific value given by f=1/2π√{square root over (LC)}, where L denotes inductance of inductor  828  and C denotes capacitance of capacitor  825 . The center frequency is in some embodiments in the range of about 20˜30 kHz, and may be preferably about 25 kHz. And an LED lamp with filtering unit  824  is able to be certified under safety standards, for a specific center frequency, as provided by Underwriters Laboratories (UL). 
     It&#39;s worth noting that filtering unit  824  may further comprise a resistor  829 , coupled between pin  501  and filtering output terminal  511 . In  FIG. 37D , resistor  829  is connected in series to the parallel-connected capacitor  825  and inductor  828 . For example, resistor  829  may be coupled between pin  501  and parallel-connected capacitor  825  and inductor  828 , or may be coupled between filtering output terminal  511  and parallel-connected capacitor  825  and inductor  828 . In this embodiment, resistor  829  is coupled between pin  501  and parallel-connected capacitor  825  and inductor  828 . Further, resistor  829  is configured for adjusting the quality factor (Q) of the LC circuit comprising capacitor  825  and inductor  828 , to better adapt filtering unit  824  to application environments with different quality factor requirements. Since resistor  829  is an optional component, it is depicted in a dotted line in  FIG. 37D . 
     Capacitance values of capacitor  825  are in some embodiments in the range of about 10 nF-2 uF. Inductance values of inductor  828  are in some embodiments smaller than 2 mH, and may be preferably smaller than 1 mH. Resistance values of resistor  829  are in some embodiments larger than 50 ohms, and are may be preferably larger than 500 ohms. 
     Besides the filtering circuits shown and described in the above embodiments, traditional low-pass or band-pass filters can be used as the filtering unit in the filtering circuit in the present invention. 
       FIG. 37E  is a schematic diagram of the filtering unit according to an embodiment of the present invention. Referring to  FIG. 37E , in this embodiment filtering unit  925  is disposed in rectifying circuit  610  as shown in  FIG. 29A , and is configured for reducing the EMI (Electromagnetic interference) caused by rectifying circuit  610  and/or other circuits. In this embodiment, filtering unit  925  includes an EMI-reducing capacitor coupled between pin  501  and the anode of rectifying diode  613 , and also between pin  502  and the anode of rectifying diode  614 , to reduce the EMI associated with the positive half cycle of the AC driving signal received at pins  501  and  502 . The EMI-reducing capacitor of filtering unit  925  is also coupled between pin  501  and the cathode of rectifying diode  611 , and between pin  502  and the cathode of rectifying diode  612 , to reduce the EMI associated with the negative half cycle of the AC driving signal received at pins  501  and  502 . In some embodiments, rectifying circuit  610  comprises a full-wave bridge rectifier circuit including four rectifying diodes  611 ,  612 ,  613 , and  614 . The full-wave bridge rectifier circuit has a first filtering node connecting an anode and a cathode respectively of two diodes  613  and  611  of the four rectifying diodes  611 ,  612 ,  613 , and  614 , and a second filtering node connecting an anode and a cathode respectively of the other two diodes  614  and  612  of the four rectifying diodes  611 ,  612 ,  613 , and  614 . And the EMI-reducing capacitor of the filtering unit  925  is coupled between the first filtering node and the second filtering node. 
     Similarly, with reference to  FIGS. 29C, and 30A-30C , any capacitor in each of the circuits in  FIGS. 30A-30C  is coupled between pins  501  and  502  (or pins  503  and  504 ) and any diode in  FIG. 29C , so any or each capacitor in  FIGS. 30A-30C  can work as an EMI-reducing capacitor to achieve the function of reducing EMI. For example, rectifying circuit  510  in  FIGS. 28C and 28E  may comprise a half-wave rectifier circuit including two rectifying diodes and having a half-wave node connecting an anode and a cathode respectively of the two rectifying diodes, and any or each capacitor in  FIGS. 30A-30C  may be coupled between the half-wave node and at least one of the first pin and the second pin. And rectifying circuit  540  in  FIG. 28E  may comprise a half-wave rectifier circuit including two rectifying diodes and having a half-wave node connecting an anode and a cathode respectively of the two rectifying diodes, and any or each capacitor in  FIGS. 30A-30C  may be coupled between the half-wave node and at least one of the third pin and the fourth pin. 
     It&#39;s worth noting that the EMI-reducing capacitor in the embodiment of  FIG. 37E  may also act as capacitor  825  in filtering unit  824 , so that in combination with inductor  828  the capacitor  825  performs the functions of reducing EMI and presenting high impedance to an external driving signal at specific frequencies. For example, when the rectifying circuit comprises a full-wave bridge rectifier circuit, capacitor  825  of filtering unit  824  may be coupled between the first filtering node and the second filtering node of the full-wave bridge rectifier circuit. When the rectifying circuit comprises a half-wave rectifier circuit, capacitor  825  of filtering unit  824  may be coupled between the half-wave node of the half-wave rectifier circuit and at least one of the first pin and the second pin. 
     The LED tube lamps according to various different embodiments of the present invention are described as above. With respect to an entire LED tube lamp, the features including “securing the glass tube and the end cap with a highly thermal conductive silicone gel”, “covering the glass tube with a heat shrink sleeve”, “adopting the bendable circuit sheet as the LED light strip”, “the bendable circuit sheet being a metal layer structure or a double layer structure of a metal layer and a dielectric layer”, “coating the adhesive film on the inner surface of the glass tube”, “coating the diffusion film on the inner surface of the glass tube”, “covering the diffusion film in form of a sheet above the LED light sources”, “coating the reflective film on the inner surface of the glass tube”, “the end cap including the thermal conductive member”, “the end cap including the magnetic metal member”, “the LED light source being provided with the lead frame”, “utilizing the circuit board assembly to connect the LED light strip and the power supply”, “the rectifying circuit”, “the terminal adapter circuit”, “the anti-flickering circuit”, “the protection circuit” and “the filament-simulating circuit” may be applied in practice singly or integrally such that only one of the features is practiced or a number of the features are simultaneously practiced. 
     Furthermore, any of the features “adopting the bendable circuit sheet as the LED light strip”, “the bendable circuit sheet being a metal layer structure or a double layer structure of a metal layer and a dielectric layer” which concerns the “securing the glass tube and the end cap with a highly thermal conductive silicone gel” includes any related technical points and their variations and any combination thereof as described in the above-mentioned embodiments of the present invention, and which concerns the “covering the glass tube with a heat shrink sleeve” includes any related technical points and their variations and any combination thereof as described in the above-mentioned embodiments. “coating the adhesive film on the inner surface of the glass tube”, “coating the diffusion film on the inner surface of the glass tube”, “covering the diffusion film in form of a sheet above the LED light sources”, “coating the reflective film on the inner surface of the glass tube”, “the LED light source being provided with the lead frame”, and “utilizing the circuit board assembly to connect the LED light strip and the power supply” includes any related technical points and their variations and any combination thereof as described in the abovementioned embodiments of the present invention. 
     As an example, the feature “adopting the bendable circuit sheet as the LED light strip” may include “the connection between the bendable circuit sheet and the power supply is by way of wire bonding or soldering bonding; the bendable circuit sheet being a metal layer structure or a double layer structure of a metal layer and a dielectric layer; the bendable circuit sheet has a circuit protective layer made of ink to reflect lights and has widened part along the circumferential direction of the glass tube to function as a reflective film.” 
     As an example, the feature “coating the diffusion film on the inner surface of the glass tube” may include “the composition of the diffusion film includes calcium carbonate, halogen calcium phosphate and aluminum oxide, or any combination thereof, and may further include thickener and a ceramic activated carbon; the diffusion film may be a sheet covering the LED light source.” 
     As an example, the feature “coating the reflective film on the inner surface of the glass tube” may include “the LED light sources are disposed above the reflective film, within an opening in the reflective film or beside the reflective film.” 
     As an example, the feature “the LED light source being provided with the lead frame” may include “the lead frame has a recess for receive an LED chip, the recess is enclosed by first sidewalls and second sidewalls with the first sidewalls being lower than the second sidewalls, wherein the first sidewalls are arranged to locate along a length direction of the glass tube while the second sidewalls are arranged to locate along a width direction of the glass tube.” 
     As an example, the feature “utilizing the circuit board assembly to connect the LED light strip and the power supply” may include “the circuit board assembly has a long circuit sheet and a short circuit board that are adhered to each other with the short circuit board being adjacent to the side edge of the long circuit sheet; the short circuit board is provided with a power supply module to form the power supply; the short circuit board is stiffer than the long circuit sheet.” 
     According to the design of the rectifying circuit in the power supply module, there may be a signal rectifying circuit, or dual rectifying circuit. First and second rectifying circuits of the dual rectifying circuit are respectively coupled to the two end caps disposed on two ends of the LED tube lamp. The single rectifying circuit is applicable to the drive architecture of signal-end power supply, and the dual rectifying circuit is applicable to the drive architecture of dual-end power supply. Furthermore, the LED tube lamp having at least one rectifying circuit is applicable to the drive architecture of low frequency AC signal, high frequency AC signal or DC signal. 
     The single rectifying circuit may be a half-wave rectifier circuit or full-wave rectifying circuit. The dual rectifying circuit may comprise two half-wave rectifier circuits, two full-wave rectifying circuits or one half-wave rectifier circuit and one full-wave rectifying circuit. 
     According to the design of the pin in the power supply module, there may be two pins in single end (the other end has no pin), two pins in corresponding end of two ends, or four pins in corresponding end of two ends. The designs of two pins in single end two pins in corresponding end of two ends are applicable to signal rectifying circuit design of the of the rectifying circuit. The design of four pins in corresponding end of two ends is applicable to dual rectifying circuit design of the of the rectifying circuit, and the external driving signal can be received by two pins in only one end or in two ends. 
     According to the design of the filtering circuit of the power supply module, there may be a single capacitor, or π filter circuit. The filtering circuit filers the high frequency component of the rectified signal for providing a DC signal with a low ripple voltage as the filtered signal. The filtering circuit also further comprises the LC filtering circuit having a high impedance for a specific frequency for conforming to current limitations in specific frequencies of the UL standard. Moreover, the filtering circuit according to some embodiments further comprises a filtering unit coupled between a rectifying circuit and the pin(s) for reducing the EMI. 
     A protection circuit may be additionally added to protect the LED module. The protection circuit detects the current and/or the voltage of the LED module to determine whether to enable corresponding over current and/or over voltage protection. 
     According to the design of the filament-simulating circuit of the power supply module, there may be a single set of a parallel-connected capacitor and resistor, two serially connected sets, each having a parallel-connected capacitor and resistor, or a negative temperature coefficient circuit. The filament-simulating circuit is applicable to program-start ballast for avoiding the program-start ballast determining the filament abnormally, and so the compatibility of the LED tube lamp with program-start ballast is enhanced. Furthermore, the filament-simulating circuit almost does not affect the compatibilities for other ballasts, e.g., instant-start and rapid-start ballasts. 
     The above-mentioned features of the present invention can be accomplished in any combination to improve the LED tube lamp, and the above embodiments are described by way of example only. The present invention is not herein limited, and many variations are possible without departing from the spirit of the present invention and the scope as defined in the appended claims.