Abstract:
A linear light-emitting diode (LED) tube lamp having a readily retrofittable modular structure enables consumers or manufacturers to readily retrofit the lamp by replacing an LED module or internal electronic control units that include an LED driver in maintenance or lamp upgrade without hazards. The readily retrofittable modular structure includes a core assembly in each of lamp bases for easily securing or removing the electronic control unit through a mechanical securing means, and two sets of connection modules for quickly connecting and disconnecting the electronic control unit with the LED module. The readily retrofittable modular structure may use one bi-pin or two bi-pins to connect to the AC mains via pluggable wire for delivering power to the LEDs. Thus, the LLT lamp using the readily retrofittable modular structure may be configured as single-ended, double-ended, or double-ended with double shock-protection switches and can be cost-effectively retrofitted after initial installation.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    This invention relates to a linear light-emitting diode (LED) lamp, and more particularly to a linear LED lamp with a readily retrofittable modular structure that enables consumers or manufacturers to readily retrofit, maintain, or upgrade the lamp by replacing an LED module or an internal LED driver. With such a retrofittable modular structure, all the workable parts with specifications that meet market demands can be reused to save resources and to reduce waste on the earth. 
         [0003]    2. Description of the Related Art 
         [0004]    Solid-state lighting from semiconductor light-emitting diodes (LEDs) has received much attention in general lighting applications today. Because of its potential for more energy savings, better environmental protection (no hazardous materials used), higher efficiency, smaller size, and much longer lifetime than conventional incandescent bulbs and fluorescent tubes, the LED-based solid-state lighting will be a mainstream for general lighting in the near future. Meanwhile, as LED technologies develop with the drive for energy efficiency and clean technologies worldwide, more families and organizations will adopt such a “green” LED lighting for their illumination applications. In this trend, even though no hazardous materials are used in an LED lamp, the lamp material reuse becomes an important environmental issue and needs to be well addressed. 
         [0005]    Whereas environmental interest groups persist to urge businesses to pay more attention to their environmental policy, Environmental Protection Agency (EPA) continues to encourage people and businesses to conserve energy, reduce waste, and even lower carbon footprint by recycling and reusing materials. On the LED lamp market, quite a number of so called “green” consumers express preferences for products and firms that are recognized to be more environment-friendly than other competitive products and companies. Such green consumers always check potential LED lamps to see if they are either recyclable or made from interchangeable parts. Besides, some green consumers express their concerns about LED lamps&#39; durability, not just to get one at a cheaper price because they know LED lamps that are more durable and repairable will last longer and therefore produce less garbage in the long run. “Green” investors including individuals and organizations always want to put their money where their environmental values are, especially for solid-state lighting—“green” products based on “green” technologies. In this sense, the linear LED tube lamp manufacturers should make an environmental decision to make their products to be more eco-friendly to be successful. 
         [0006]    Although LEDs themselves can operate at least 50,000 hours, the LED driver that operates the LEDs in a linear LED tube (LLT) lamp in most cases cannot last so long because of potential failures of a LED driver in which electrolytic capacitors or other electronic components used are likely to fail prematurely. Upon failure, the LED driver needs to be replaced. But if the LED driver, typically about 10-15% of the cost of an LLT lamp, is not cost-effectively replaceable, then the whole lamp needs to be replaced and becomes waste. However, if the LLT lamp is so designed that internal LED driver can be easily removed and replaced, consumers or manufacturers can replace the LED driver only and not the whole lamp. That way, the manufacturers can reuse all other workable parts with specifications that meet market demands and rebuild the LLT lamp, saving about 85-90% of cost of the lamp with all the workable parts including the LED module, lamp bases, heat sink and housing, lens, and so on. 
         [0007]    Furthermore, as LED technologies and standards continue to develop rapidly, requirements of an LED luminous efficacy of 100 lumens per watt and a color rendering index (CRI) of 80 today will be unsatisfactory tomorrow to consumers and the Energy Star program. Market also requires a minimum number of surface mount LEDs used in the LED module and a specific correlated color temperature (CCT) tolerance for LED chips. So, for example, a minimum requirement of 264 LEDs in a 4-ft-T8 LLT lamp and a CCT tolerance of 175 K (Kelvin) today may be obsolete tomorrow. Similarly for LED drivers, requirements of a power factor of 0.9, a total harmonic distortion (THD) less than 20%, and a power consumption of 20 W today may not be good enough tomorrow for energy firms to offer energy rebates, a great incentive for consumers and organizations to adopt LED lamps. In this case, outdated LED modules and LED drivers may need to be replaced with upgraded ones to meet updated consumer needs and new standards. 
         [0008]    It is, therefore, the manufacturers&#39; environmental responsibility to design a readily retrofittable LLT lamp such that the redesign efforts are beneficial to lifetime cost of ownership and environmental protection. It seems simple and straightforward, but not single one of manufacturers adopts the idea and builds such products today, whereas an LLT lamp costs only several tens of dollars, and price competition continues to be severe on the market; manufacturers are just trying to produce such LLT lamps at the lowest cost. 
         [0009]    To retrofit a conventional LLT lamp for replacing an existing LED driver, one must first remove the two end caps and then cut the AC wires that connect to the AC mains through two opposite bi-pins in the two end caps or de-solder the wires from their respective soldering joints in the two end caps. Then one must disconnect DC wires connected between the LED driver and the LED module by cutting or de-soldering the wires from their respective soldering joints/contacts on the LED PCB (printed circuit board). If the LED driver is not mechanically fixed, then it can be removed immediately after all the wires are released. However, the LED driver should be mechanically secured in an LLT lamp, not relying solely on the electrical contacts, to prevent possible electric shock hazards that occur when any one of the wires is accidentally detached from the soldering joint with the exposed conductor touching the metallic housing. Therefore, Underwriters Laboratories (UL) requires the LLT lamp to meet this consumer safety need. If the LED driver is fixed inside an LLT lamp using a rivet, then one needs to first remove the LED PCB on the upper platform of the lamp housing and then drill the rivet out of the place and then remove the LED driver. The replacement work is tedious and labor intensive; when LED PCB is removed from the platform of the aluminum housing, the LED PCB becomes bent, preventing it from reuse. Thus, no manufacturers would like to replace the LED driver even though the LED driver is broken, but would rather replace the whole lamp, leaving the whole non-operable lamp as a piece of garbage. This kind of products is not eco-friendly and will eventually be rejected by consumers, especially by “green” consumers. 
         [0010]    Referring to  FIGS. 1 and 2 , a conventional LLT lamp  100  comprises a housing  110  with a length much greater than its diameter of 25 to 32 mm, two end caps  120  and  130  with bi-pins  180  and  190  respectively on two opposite ends of the housing  110 , LED arrays  140  mounted on a printed circuit board (PCB)  150 , and an LED driver  160  used to receive energy from the AC mains, 110 V, 220 V, or 277 VAC, through electrical contacts  142  and the bi-pins  180  and  190 , to generate a proper DC voltage with a proper current, and to supply it to the LED arrays  140  such that the LEDs  170  on the PCB  150  can emit light. In some conventional LLT lamps, the LED driver wrapped by an insulation paper or a heat shrinking tube is inserted into the LLT lamp without being mechanically secured. The electrical wires connected to the AC mains may come off from the soldering joints at the electrical contacts  142 , which may create a safety issue not acceptable for UL and consumers. Therefore, in some conventional LLT lamps, a rivet (not shown) on the upper platform of the housing is used to secure the LED driver in place under the platform. When the LED PCB is attached on the upper platform of the housing, the rivet can no longer be accessed without first detaching LED PCB from the housing. This means that the LED driver cannot be removed unless the rivet is removed first. Soldering joints  152  and  153  are used to connect the LED driver output DC+ and DC− to the LED arrays. The bi-pins  180  and  190  on the two opposite end caps  120  and  130  connect electrically to the AC mains through two electrical sockets located lengthways in an existing fluorescent tube fixture whereas the two sockets in the fixture connect electrically to the line and the neutral wire of the AC mains, respectively. This is a so called “double-ended” configuration. 
         [0011]    To replace a fluorescent tube with an LLT lamp  100 , one inserts the bi-pin  180  at one end of the LLT lamp  100  into one of the two electrical sockets in the fixture and then inserts the other bi-pin  190  at the other end of the LLT lamp  100  into the other electrical socket in the fixture. When the line power of the AC mains applies to the bi-pin  180  through one socket, and the other bi-pin  190  at the other end is not yet in the other socket in the fixture, the LLT lamp  100  and the LED driver  160  are deactivated because no current flows through the LED driver  160  to the neutral. However, the internal electronic circuitry is live. At this time, if the person who replaces the LLT lamp  100  touches the exposed bi-pin  190 , which is energized, he or she will get an electric shock because the current flows to earth through his or her body—a shock hazard. 
         [0012]    Almost all the LLT lamps currently available on the market are without any protections for such electric shock. The probability of getting shock is 50%, depending on whether the person who replaces the lamp inserts the bi-pin first to the line of the AC mains or not. If he or she inserts the bi-pin  180  or  190  first to the neutral of the AC mains, then the LLT lamp  100  is deactivated because the internal circuitry is not live—no shock hazard. An LLT lamp supplier may want to adopt single protection only at one end of an LLT lamp in an attempt to reduce the risk of shock during re-lamping. However, such a single protection approach cannot completely eliminate the possibility of shock risk. 
         [0013]    An easy solution to reducing the risk of shock is to connect electrically only one of two bi-pins at the two ends of an LLT lamp to the AC mains, leaving the other bi-pin at the other end of the LLT lamp electrically insulated. Thus, the line and the neutral of the AC mains go into the LLT lamp through the single-ended bi-pin, one for “line” (denoted as L, hereafter) and the other for “neutral” (denoted as N, hereafter). The electrically insulated bi-pin at the other end only serves as a lamp holder to support the LLT lamp mechanically in the fixture. The LLT lamp configured this way is therefore called “single-ended”. 
         [0014]    In  FIG. 3 , the AC mains supply voltage to the bi-pin socket  255  in the lamp holder  311  from an end of the LLT lamp  101  leaving the lamp holder  312  electrically insulated—a single ended configuration. Two pins  181  and  182  of the bi-pin are at one end, from which the driver  400  receives energy to power the LED arrays  214 . The conductors in the bi-pin socket  255  of the lamp holder  311  are used to connect the bi-pins to the AC mains through electrical contacts shown as dots. The “dot” notation will be used to indicate electrical contacts throughout the figures. 
         [0015]    In  FIG. 4 , the driver  400  receives energy from both bi-pin sockets  255  and  256  in the lamp holders  313  and  314  at opposite ends of the LLT lamp  102  to power the LED arrays  214 —a double-ended configuration. The two pins  181  and  182  at one end are internally interconnected with a conductor  253 . Similarly, the two pins  183  and  184  at the other end are internally interconnected with a conductor  254 . In this case, as long as either one of the two pins  181  and  182  in the bi-pin socket  255  and either one of the two pins  183  and  184  in the bi-pin socket  256  receive power, the LLT lamps can operate. 
         [0016]    In the U.S. Pat. No. 8,147,091, issued Apr. 3, 2012, the entirety of which is incorporated herein by reference, double shock protection switches are used in a double-ended LLT lamp to isolate its LED driver such that a leakage current flowing from a live bi-pin, through the LED driver, to an exposed bi-pin is eliminated without shock hazards.  FIGS. 5 and 6  illustrate an LLT lamp with such shock protection switches. The LLT lamp  200  comprises a housing  201 ; two lamp bases  260  and  360 , one at each end of the housing  201 ; two actuation mechanisms  240  and  340  of shock protection switches  210  and  310  in the two lamp bases  260  and  360 , respectively; an LED driver  400 ; and LED arrays  214  on an LED PCB  205 . Soldering joints  152  and  153  are used to connect the driver output DC+ and DC− to the LED arrays. 
         [0017]      FIG. 6  is a block diagram of an LLT lamp  200  with the shock protection switches  210  and  310 . The shock protection switch  210  comprises two electrical contacts  220  and  221  and one actuation mechanism  240 . Similarly, a shock protection switch  310  comprises two electrical contacts  320  and  321  and one actuation mechanism  340 . The electrical contact  220  in the shock protection switch  210  connects electrically to the bi-pin  250  that connects to the L wire of the AC mains, and the other contact  221  connects to one of the inputs  270  of the LED driver  400 . Similarly, the electrical contact  320  in the shock protection switch  310  connects electrically to the bi-pin  350  that connects to the N wire of the AC mains, and the other contact  321  connects to the other input  370  of the LED driver  400 . The shock protection switches  210 ,  310  are normally off. Only after being actuated, will the shock protection switches turn “on” such that they connect the AC mains to the LED driver  400  that in turn powers the LED arrays  214 . Serving as gate controllers between the AC mains and the LED driver  400 , the shock protection switches  210  and  310  connect the line and the neutral of the AC mains to the two inputs  270  and  370  of the driver  400 , respectively. If only one shock protection switch  210  is used at one lamp base  260 , and if the bi-pin  250  of this end happens to be first inserted into the live socket at one end of the fixture, then a shock hazard can occur because the shock protection switch  210  already allows the AC power to electrically connect to the driver  400  inside the LLT lamp when the bi-pin  250  is in the socket. Although the LLT lamp  200  is deactivated at the time, the LED driver  400  is live. Without the shock protection switch  310  at the other end of the LLT lamp  200 , the driver input  370  connects directly to the bi-pin  350  at the other end of the LLT lamp  200 . This presents a shock hazard. However, if the shock protection switch  310  is used in accordance with this application, the current flow to the earth continues to be interrupted until the bi-pin  350  is inserted into the other socket, and the protection switch  310  is actuated. The switch redundancy eliminates the possibility of shock hazard for a person who installs an LLT lamp in the existing fluorescent tube fixture. 
         [0018]    Almost all the commercially available LLT lamps today—single-ended, double-ended, or double-ended with double shock-protection switches use wire soldering approach to directly connect the LED driver output to the LED arrays and to directly connect the bi-pins in the end cap to the LED driver inputs. This approach prevents the LED driver used from being easily replaced in the first place. Furthermore, the driver not being mechanically secured may create consumer safety problems whereas the driver being mechanically secured with rivets, screws, or some other improper ways, is even more difficult to be replaced. 
       SUMMARY OF THE INVENTION 
       [0019]    It is an object of the invention to provide a readily retrofittable modular structure for any LLT lamps configured as single-ended, double-ended, or double-ended with shock protection switches so that the internal driver used in such LLT lamps can be replaced as easily as an external driver, which sometimes can be replaced without disassembling the lamp itself in the field. Retrofitting an LED module that comprises LED arrays and the lamp housing is the same as replacing an LED driver. Only difference is that the driver removed is to be reused with an upgraded LED module. This is essential for long-term maintenance and retrofit for linear LED lighting products. 
         [0020]    According to the invention, the retrofittable LLT lamp comprises an elongated housing having two ends and a platform on a top side thereof between the two ends; an LED PCB fixed on top of the platform, the LED PCB having LED arrays and at least one first connection module thereon; at least one electronic control unit that controls the power to the LED arrays on the LED PCB, the at least one electronic control unit having two inputs and a second connection module thereon; and two lamp bases respectively connected to the two ends of the housing, each lamp base having an end cover comprising a bi-pin with two pins protruding outwards through the end cover and an intermediate core assembly comprising a securing means used to mechanically couple one electronic control unit and a compartment used to accommodate at least one connection terminal for one AC power pluggable wire. 
         [0021]    In an embodiment, at least one electronic control unit is an LED driver. The LED driver is mechanically coupled with a first core assembly through the securing means that comprises a dowel to couple a hole on the LED driver and a platform on the core assembly to partially support the LED driver in a way that when the lamp base is coupled with the lamp housing, the LED driver is pushed into a hollow compartment under the platform of the lamp housing, and the second connection module on the LED driver is automatically coupled with the first connection module on the LED PCB to make a reliable DC power connection. In the single-ended lamp, the AC power connection is done by using two AC pluggable wires plugging onto the connection terminals in the first core assembly in the lamp base. In the double-ended lamp, the AC power connection is done by using two AC pluggable wires plugging onto the connection terminals, each in the first core assembly and a second core assembly in the lamp bases. For the double-ended lamp with double shock protection switches, the AC power connection is done by using two AC pluggable wires plugging onto the connection terminals on the switches, each in the first core assembly and a second core assembly in the lamp bases. 
         [0022]    With this readily retrofittable modular structure (readily retrofittable mechanism, thereafter), the linear LED lamp can be cost-effectively retrofitted or upgraded. For example, when the LED driver needs to be replaced, one can remove the lamp base to pull out the LED driver, and at the same time to electrically and mechanically disconnect the LED driver from the LED PCB. Then one can unplug the two AC pluggable wires from the connection terminals in the core assembly/assemblies, depending on single- or double-ended configuration. This way, the LED driver can be taken out from the lamp without cutting or de-soldering any wires. Similarly for installing a new LED driver, one can just follow reverse procedures, no need to make wire connections or to solder any wires. What is most important is that because the AC connection terminals are embedded inside the core assembly/assemblies which are made of an insulated plastic material, and because DC connection between the LED driver and the LED PCB is through the connection modules thereon, AC and DC paths are well separated and insulated; there is no possibility that the AC voltage can mess up in the DC path with a leakage current flowing on the metallic housing, which may create an electric shock hazard for consumers. To prevent consumers from injury due to this shock hazard, UL uses one of the procedures in UL 1993 Standards, Dielectric Voltage-Withstand Test, to determine if LLT lamps under test meet the consumer safety requirements. 
         [0023]    Because the readily retrofittable mechanism implemented in the LLT lamp enables consumers or manufacturers to cost-effectively upgrade the LLT lamp without possible misuse of mechanical and electrical connections between the LED PCB and the LED driver and between the LED driver and the AC connection terminals, they are willing to do the upgrade by only replacing the LED driver or the LED module that need to be replaced. Therefore, all the workable parts such as the LED driver, the LED module comprising a plurality of LEDs on the LED PCB, the heat sink or lamp housing, lamp bases, and the lens to be described in detail below can be reused to save resources and to reduce waste on the earth. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0024]      FIG. 1  is an illustration of a conventional LLT lamp. 
           [0025]      FIG. 2  is a block diagram of a conventional LLT lamp. 
           [0026]      FIG. 3  is a block diagram of a conventional single-ended LLT lamp. 
           [0027]      FIG. 4  is a block diagram of a conventional double-ended LLT lamp. 
           [0028]      FIG. 5  is an illustration of a double-ended LLT lamp with shock protection switches. 
           [0029]      FIG. 6  is a block diagram of a double-ended LLT lamp with shock protection switches. 
           [0030]      FIG. 7  is a perspective view of a core assembly in a lamp base according to the present invention. 
           [0031]      FIG. 8  is a perspective view of a lamp base comprising the core assembly according to the present invention. 
           [0032]      FIG. 9  is a side view of a lamp base comprising the core assembly and a pluggable wire according to the present invention. 
           [0033]      FIG. 10  is a perspective view of a connection module in an LED driver according to the present invention. 
           [0034]      FIG. 11  is a perspective view of a connection module in an LED lighting board according to the present invention. 
           [0035]      FIG. 12  is a perspective view of an embodiment of the readily retrofittable mechanism before the lamp base is coupled to an LLT lamp according to the present invention. 
           [0036]      FIG. 13  is a perspective view of an embodiment of the readily retrofittable mechanism after the lamp base is coupled to an LLT lamp according to the present invention. 
           [0037]      FIG. 14  is a cross-sectional view of an embodiment of the readily retrofittable mechanism in an LLT lamp according to the present invention. 
           [0038]      FIG. 15  is a perspective view of a double-ended LLT lamp with shock protection switches and with the readily retrofittable mechanism according to the present invention. 
           [0039]      FIG. 16  is a block diagram of a double-ended LLT lamp with shock protection switches and with the readily retrofittable mechanism according to the present invention. 
           [0040]      FIG. 17  is a block diagram of a double-ended LLT lamp with the readily retrofittable mechanism according to the present invention. 
           [0041]      FIG. 18  is a block diagram of a single-ended LLT lamp with the readily retrofittable mechanism according to the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0042]    Referring to  FIGS. 7 ,  8 ,  9 , and  14 , a core assembly  500  comprises a circular interface ring  501  concentric to the inner wall of an end cover  502 , a horizontal channel  503  used to position the core assembly  500  with the aluminum heat sink housing  802  (in  FIG. 14 ) by embedding an end of platform  803  (in  FIG. 14 ) of the heat sink housing  802  into the channel  503 , a supporting surface  510  to support an LED driver  600  (in  FIG. 14 ), a mechanical securing means  511  on the supporting surface  510  to hold and secure the LED driver  600 , a bi-pin  509  for connecting to a socket for an LLT lamp, a hollow compartment  513  under the supporting surface  510  for holding the AC connection terminals  514  (in  FIG. 9 ) and a lead wire (not shown) that electrically connects to a bi-pin  509 , and two holes  512  each for accommodating an AC power pluggable wire  515  inserted and connected to one of the AC connection terminals  514 . The supporting surface  510  on the core assembly  500  should be long enough to partially support the LED driver and be protruded in a way that it can be partially inside the lamp housing under the platform  803  when the lamp base  550  that includes the end cover  502  is connected to the lamp housing  802 . On the supporting surface  510 , the mechanical securing means  511  used is a dowel, which can be replaced with two or more dowels. Other possibilities for holding and securing the LED driver  600  include a tap hole with a fixing screw, a retaining clip, or other similar means. In this embodiment, the LED driver  600  is held and secured by using the mechanical securing means  511  in one of two lamp bases. Other electronic control units including a dimming control unit or a ZigBee controller may be attached to the other lamp base by the same mechanical securing means  511 . 
         [0043]    Introducing an intermediate core assembly  500  to interface the end cover  502  and the lamp housing  802  offers another advantage which a person having ordinary skill in the art always ignore. The end cover  502  contains an outward bi-pin that connects to the AC mains, and the inner side of the end cover  502  unavoidably has exposed live traces or connection joints. Without the plastic core assembly which is insulated as an interface, when the end cover  502  and the heat sink housing  802  are connected, the live traces or the connection joints may contact the metallic heat sink and short—an electric shock hazard. So the intermediate core assembly  500  also serves as a buffer intended to physically limit access to live parts that pose a risk of electric shock. Thus, with the intermediate core assembly  500  in place, retrofitting an LLT lamp can be straightforwardly done by a consumer without any safety concern. 
         [0044]    In  FIG. 8 , the core assembly  500  is coupled with the end cover  502  to form a lamp base  550  by the concentric interface ring  501  (in  FIG. 7 ) and an internal positioning means in the end cover  502 . In  FIG. 9 , the AC power pluggable wire  515  is further inserted into one of the holes  512  and connected to one of the AC connection terminals  514  in the hollow compartment  513 . The other end of the AC power pluggable wire  515  is connected to one of the inputs of the LED driver  600 . After installing the AC power pluggable wire  515  and an LED driver, one can install the lamp base  550  by using screws to secure the end cover  502  and the core assembly  500  through the screw holes (not shown) in the end cover  502  and the screw holes  504  (in  FIG. 7 ) in the core assembly  500  all the way to the end of an LLT lamp  900  (in  FIG. 14 ). 
         [0045]    For the single-ended application, two holes  512  and two connection terminals  514  are needed for two AC power pluggable wires  515  to connect to the AC mains because the power is delivered from the bi-pin at the same lamp end. For the double-ended application, one of the holes  512  and one of the connection terminals  514  in each lamp base at opposite end are used to connect to the AC mains because the power is delivered from the bi-pins at the two opposite lamp ends. For the double-ended application with double shock-protection switches, the connections are the same as the double-ended application. Only difference is that the AC power pluggable wire  515  is connected to the connection terminals  514  on a shock protection switch (in  FIG. 9 ) in the core assembly  500 . The shock protection switch of each of the lamp bases comprises at least two electrical contacts, one electrically connected to the bi-pin of the lamp base and the other electrically connected to one of the inputs of the LED driver, now through the connection terminals  514 ; and at least one switch actuation mechanism  905  (shown in  FIG. 9 ) having a front portion protruding outwards through the end cover of the lamp base, wherein when the front portion of the switch actuation mechanism is actuated by inserting the bi-pin of the lamp base into a lamp socket, the two electrical contacts are electrically connected to actuate the shock protection switch so that the bi-pin is electrically connected with one of the inputs of the LED driver. Spring  906  in  FIG. 9  is used to provide a stretching force for the switch actuation mechanism  905  to keep deactivated so that the shock protection switch is maintained an off-state when the lamp is not in the fixture and during relamping. 
         [0046]    In the above embodiment, only one electronic control unit which is the LED driver is used. Two electronic control units may be used with the two core assemblies at the opposite ends of the lamp, taking the same advantage of being readily retrofitted. The electronic control units that may be used in this case include the LED driver, a dimming control unit, a ZigBee controller, or an LED driver in part. The LED driver in part means that the LED driver may be divided into two parts installed respectively in the two core assemblies at the opposite ends of the lamp for another purposes. 
         [0047]    Referring to  FIGS. 10 ,  11 ,  12 , and  13 , the second connection module  601  in an LED driver  600  is used to electrically connect to an LED lighting board  700  through the first connection module  701  on the LED PCB  707 . Two connection pins  602  and  603  in the second connection module  601  are used to couple with two connection slots  702  and  703  (not shown) on the back of the first connection module  701  on the LED lighting board  700 . In  FIG. 10 , a hole  606  on the LED driver PCB  605  is used to couple with the dowel  511  on the core assembly  500  in the lamp base  550  and to mechanically secure the LED driver  600  with the support of the supporting surface  510  on the core assembly  500  in the lamp base  550  so that when the lamp base  550  is mechanically connected with the lamp housing  802 , the LED driver  600  is pushed into the bottom compartment  804  of the lamp housing  802 , whereas when the lamp base  550  is removed from the lamp housing  802 , the LED driver  600  is pulled out from the bottom compartment  804  of the lamp housing  802  and can then be easily removed from the dowel  511  on the core assembly  500  in the lamp base  550 . The hole  606  on the LED driver PCB  605  can also be used with the tap hole (the position of the dowel  511 ) on the core assembly  500  in the lamp base  550  to mechanically secure the LED driver  600  with a fixing screw. Another possibility is that the hole  606  on the LED driver PCB  605  is used with the retaining clip on the core assembly  500  in the lamp base  550  to grip the LED driver  600  in place. 
         [0048]    In  FIG. 11 , a cutout  708  on the LED PCB  707  is used to guide and accommodate the width of the second connection module  601  on the LED driver  600 . The first connection module  701  is mounted along an edge of the cutout  708  with the pins  704  and  705  soldered on the LED PCB  707 . In  FIG. 12 , the LED lighting board  700  is fixed on top of the platform  803  of the housing  802  whereas the LED driver  600  is inserted into the hollow bottom compartment  804  under the platform  803 . The platform  803  has a similar cutout as the cutout  708  to accommodate the width of the second connection module  601 . The LED PCB  707  and the driver PCB  605  are not in the same plane. So one of the challenges is how to precisely couple the two connection modules  601  and  701  such that the two connection pins  602  and  603  in the second connection module  601  can be three-dimensionally coupled with two connection slots  702  and  703  on the back of the first connection module  701  in the LED lighting board  700 . The cutout  708  provides a horizontal guiding in the first place followed by the use of the pins  704  and  705  soldered on the LED PCB  707  to provide a vertical flexibility. In combination, they can offer enough tolerance of mechanical precision and make mechanical coupling and electrical connections easier and faster, thus reducing retrofit cost. That is, when the second connection module  601  on the LED driver  600  is pushed into the first connection module  701  on the LED lighting board  700 , the two connection pins  602  and  603  in the second connection module  601  and the connection slots  702  and  703  on the back of the first connection module  701  are mated so that mechanical coupling and electrical connections can be made in the shortest period of time. This is essential for cost-effective LED driver replacement. After assembling, the two connection modules  601  and  701  are coupled with electrical connections automatically made—no lead wires or wire soldering needed. This completely eliminates electrical wire management in the small lamp base area. Furthermore, the LED lighting board  700  and the LED driver  600  are respectively disposed on top and bottom of the platform  803  of the housing  802 , separated by the platform  803 . If there is a wire interconnection between the LED lighting board  700  and the LED driver  600 , the wires must cross the platform  803  to make an electrical connection. It is possible that part of the wires is squeezed between the lamp base  550  and the cross section of the platform  803  when the lamp base  550  is fixed on the lamp housing, leading to broken wires. On the other hand, when the lamp base  550  is removed from the lamp housing  802 , the LED driver  600  is pulled out from the bottom compartment  804  of the lamp housing  802 , and at the same time, the second connection module  601  in the LED driver  600  is decoupled from the first connection module  701  in the LED lighting board  700 , automatically disconnecting the electrical connection between the LED driver  600  and the LED lighting board  700 —no wire cutting or de-soldering is needed. 
         [0049]    In  FIG. 12 , when assembling an LLT lamp  800 , the AC power pluggable wire  515  must be first inserted into the hole  512  and then plugged onto the connection terminal  514  in the core assembly  500  in the lamp base  550 . The other end of the AC power pluggable wire  515  can be soldered to the LED driver  600  or be connected with a connector on the LED driver  600  to make an AC connection. In disassembling the LLT lamp  800 , when the lamp base  550  is removed from the lamp housing  802 , the AC power pluggable wire  515  can be accessed and removed from the connection terminal  514  in the core assembly  500  in the lamp base  550 , and then the LED driver  600  can be immediately removed and replaced. 
         [0050]      FIG. 13  is a perspective view of an embodiment of a readily retrofittable mechanism after the lamp base  550  is coupled to an LLT lamp  900  with a lens (not shown for clarity).  FIG. 14  is a cross-sectional view of the LLT lamp  900  that adopts the readily retrofittable mechanism. As shown in  FIGS. 13 and 14 , the elongated lamp housing  802  made of aluminum is served as a heat sink of the lamp. On the platform  803  of the lamp housing  802  is an LED PCB  707  whereon the LED arrays  706  are mounted. In the hollow bottom compartment  804  under the platform  803 , the LED driver  600  is secured on the dowel  511  (with the dowel  511  inserted through the hole  606 ) on the core assembly  500  in the lamp base  550  when the lamp base  550  is coupled to an end of the lamp housing  802 . The LED driver  600  is mounted in such a way that the electronic components  607  thereof on the LED driver PCB  605  face downward. Depending on the lamp configurations—single-ended, double-ended, or double-ended with double shock-protection switches, the AC power pluggable wires  515  connect differently to the connection terminals  514  in the core assembly  500  in the lamp base  550 . For example, in the single-ended application, two AC power pluggable wires  515  are used at a single lamp base, leaving the other lamp base electrically insulated. In the double-ended application, the two AC power pluggable wires  515  are used separately in two lamp bases at two opposite ends of the lamp. For the double-ended application with double shock-protection switches, the connections are the same as those in the double-ended application except that the AC power pluggable wires  515  are connected to the connection terminals  514  on the shock protection switches in the lamp bases at the two opposite ends of the lamp. On each of the two end covers  502  are two screw holes for the two lamp bases  550  to be fixed on the lamp housing  802  to form a complete lamp. On the lamp housing  802  along two longitudinal sides of the platform  803  are two elongated troughs  901  to secure the lens  903 , through which the LED arrays emit the light to the ambient. The installation and removal of the lens  903  should be easy because of this trough design. On the LED PCB  707 , the connection module  701  is coupled with the connection module  601  in the LED driver  600 . 
         [0051]      FIG. 15  is a perspective view of an LLT lamp  900  that adopts a readily retrofittable mechanism with a lens (not shown for clarity).  FIG. 16  is a block diagram of a double-ended LLT lamp  900  with shock protection switches and the readily retrofittable mechanism. Referring to  FIGS. 15 and 16 , the lamp  900  is for double-ended application with double shock-protection switches in both lamp bases  550 , in which two switch actuation mechanisms  905  are shown. The soldering joints  152  and  153  on the LED PCB  205  (as shown in  FIG. 5 ) are replaced with a combination of the connection modules  601  and  701  electrically connected to deliver DC power from the LED driver  600  to the LED PCB  707  for LED arrays  706  to emit light. Two lamp bases  550  are respectively attached to the two ends of the LLT lamp housing  802  to form the lamp  900  as a stand-alone lighting device. Each lamp base  550  has an end cover  502  comprising a bi-pin with two pins  509  protruding outwards through the end cover, and the core assembly  500  comprising a mechanical securing means (such as a dowel  511 ) to secure the LED driver  600 , wherein: when the lamp base  550  with the core assembly  500  with the LED driver  600  secured thereon is fixed to the LLT lamp housing  802  on which the LED PCB  707  is fixed, the LED lighting board  700  (or LED PCB  707 ) is electrically connected to the LED driver  600  through the linkage  670  of the mechanical securing means (namely, by mating between the dowel  511  and the hole  606  in the LED driver  600 ). In  FIG. 16 , two shock protection switches  983 , one each in the two core assemblies  500 , are shown. Two pluggable wires  515  connecting the LED driver  600  to the connection terminals  514  on the shock protection switches  983  are also shown. Therefore, as the AC power is delivered to the lamp  900  with the shock protection switches  983  actuated, the LED arrays  706  can emit light. 
         [0052]      FIG. 17  is a block diagram of a double-ended LLT lamp  910  adopting the readily retrofittable mechanism. The functions are almost the same as the double-ended LLT lamp  900  with shock protection switches except that the shock protection switches  983  are not used in the double-ended LLT lamp  910 . Two core assemblies  500  are included, one each in the two lamp bases  550  for one connection terminal  514  to be secured therein. The AC power pluggable wires  515  can be easily plugged onto the connection terminal  514  through the hole  512  of each core assembly  500  and make electrical connections so that the AC power can be delivered. 
         [0053]      FIG. 18  is a block diagram of a single-ended LLT lamp  920  adopting the readily retrofittable mechanism. The functions are almost the same as the double-ended LLT lamp  900  except that the power is delivered from one bi-pin at one of the two ends of the lamp  920 . In this case, the only core assembly  500  have two connection terminals  514  secured therein for the AC power pluggable wires  515  to be easily plugged in and make an electrical connection with the two connection terminals  514  so that the AC power can be delivered. 
         [0054]    Whereas preferred embodiments of the invention have been shown and described, it will be realized that alterations, modifications, and improvements may be made thereto without departing from the scope of the following claims. Another readily retrofittable mechanism in an LLT lamp using various kinds of combinations to accomplish the same or different objectives could be easily adapted for use from the present invention. Accordingly, the foregoing description and attached drawings are by way of example only, and are not intended to be limiting.