Patent Publication Number: US-8531118-B2

Title: AC light emitting diode and AC LED drive methods and apparatus

Description:
RELATED APPLICATIONS 
     The present application is a continuation of U.S. patent application Ser. No. 12/364,890 filed Feb. 3, 2009, now U.S. Pat. No. 8,148,905 which is a continuation of U.S. patent application Ser. No. 11/066,414 filed Feb. 25, 2005 now U.S. Pat. No. 7,489,086, which claims priority to U.S. Provisional Application No. 60/547,653, filed Feb. 25, 2004 and U.S. Provisional Application No. 60/559,867, filed Apr. 6, 2004; the contents of all of which are expressly incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present invention generally relates to light emitting diodes (“LEDs”) and LED drivers. The present invention specifically relates to alternating current (“AC”) driven LEDs, LED circuits and AC drive circuits and methods. 
     FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     None. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention generally relates to light emitting diodes (“LEDs”) and LED drivers. The present invention specifically relates to alternating current (“AC”) driven LEDs, LED circuits and AC drive circuits and methods. 
     2. Description of the Related Art 
     LEDs are semiconductor devices that produce light when a current is supplied to them. LEDs are intrinsically DC devices that only pass current in one polarity and historically have been driven by DC voltage sources using resistors, current regulators and voltage regulators to limit the voltage and current delivered to the LED. Some LEDs have resistors built into the LED package providing a higher voltage LED typically driven with 5V DC or 12V DC. 
     With proper design considerations LEDs may be driven more efficiently with AC than with DC drive schemes. LED based lighting may be used for general lighting, specialty lighting, signs and decoration such as for Christmas tree lighting. For example, U.S. Pat. No. 5,495,147 entitled LED LIGHT STRING SYSTEM to Lanzisera (hereinafter “Lanzisera”) and U.S. Pat. No. 4,984,999 entitled STRING OF LIGHTS SPECIFICATION to Leake (hereinafter “Leake”) describes different forms of LED based light strings. In both Lanzisera and Leake, exemplary light strings are described employing purely parallel wiring of discrete LED lamps using a step-down transformer and rectifier power conversion scheme. This type of LED light string converts input electrical power, usually assumed to be the common U.S. household power of 110 VAC, to a low voltage, rectified to nearly DC input. 
     Pat. Pending Application No. 0015968A1 entitled PREFERRED EMBODIMENT TO LED LIGHT STRING to Allen (hereinafter “Allen”) discloses AC powered LED-based light strings. Allen describes LED light strings employing series parallel blocks with a voltage matching requirement for direct AC drive placing fundamental restrictions on the number of diodes (LEDs) on each diode series block, depending on the types of diodes used. Allen discloses that for the forward voltage to be “matched,” in each series block, the peak input voltage must be less than or equal to the sum of the maximum forward voltages for each series block in order to prevent over-driving. 
     LEDs can be operated from an AC source more efficiently if they are connected in an “opposing parallel” configuration as shown by WO98/02020 and JP11/330561. More efficient LED lighting systems can be designed using high frequency AC drivers as shown by Patent Publication Number 20030122502 entitled Light Emitting Diode Driver (“Clauberg et. al.”) Clauberg et. al. discloses that higher frequency inverters may be used to drive an opposing parallel LED pair, an opposing parallel LED string and/or an opposing parallel LED matrix by coupling the LEDs to a high frequency inverter through a resonant impedance circuit that includes a first capacitor coupled in series to one or more inductors with the impedance circuit coupled in series to opposing parallel LEDs with each set of LEDs having a second series capacitor in series to the impedance circuit. In this system additional opposing parallel configurations of LEDs with capacitors may not be added to or removed from the output of the driver without effecting the lumens output of the previously connected LED circuits unless the driver or components at the driver and/or the opposing parallel LED capacitors were replaced with proper values. By adding or removing the opposing parallel LED circuits the voltage would increase or drop at the inductor and the current would increase or drop through the first series capacitor as the load changed therefore the inductor and all capacitors or entire driver would need to be replaced or adjusted each time additional LEDs were added to or removed from the system. 
     Patent application number US2004/0080941 entitled Light Emitting Diodes For High AC Voltage Operation And General Lighting discloses that a plurality of opposing parallel series strings of LEDs can be integrated into a single chip and driven with high voltage low frequency mains AC power sources as long as there are enough LEDs in each opposing parallel series string of LEDs to drop the total source voltage across the series LEDs within the chip. Patent numbers WO2004023568 and JP2004006582 disclose that a plurality of opposing parallel series strings or opposing parallel series matrix of LEDs can be integrated into a single chip and mounted on an insulating substrate and driven with a high drive voltage and low drive current as long as there are enough LEDs in each opposing parallel series string of LEDs to drop the total source voltage across the series LEDs within the chip. These patents and application disclose that for single chip or packaged LED circuits a plurality of opposing parallel series strings are required with the total number of LEDs in each series string needing to be equal to or greater than the AC voltage source in order to drop the total forward voltage and provide the required drive current when driven direct with low frequency AC mains power sources. 
     The present invention addresses the above-noted shortcomings of the prior art while providing additional benefits and advantages 
     SUMMARY OF THE INVENTION 
     According to one broad aspect of the invention a lighting system is provided having one or more LED circuits. Each LED circuit has at least two diodes connected to each other in opposing parallel relation, wherein at least one of which such diodes is an LED. As used throughout the application, the term diode may mean any type of diode capable of allowing current to pass in a single direction, including but not limited to, a standard diode, a schottky diode, a zener diode, and a current limiting diode. A driver is connected to the one or more LED circuits, the driver providing an AC voltage and current to the one or more LED circuits. The driver and the LED circuits form a driven circuit. The driver and the LED circuits are also configured such that LED circuits may be added to or subtracted (intentionally or by component failure) from the driven circuit:
         (a) without significantly affecting the pre-determined desired output range of light from any individual LED; and,   (b) without the need to: (i) change the value of any discrete component; or, (ii) to add or subtract any discrete components, of any of the pre-existing driven circuit components which remain after the change.       

     In another embodiment of the invention at least one capacitor is connected to and part of each LED circuit. In yet another embodiment, at least one resistor is connected to and is part of each opposing parallel LED circuit noted above. The resistor is connected in series with the at least one capacitor. 
     According to another aspect of the invention an LED circuit (sometimes referred to as an “AC LED”) can comprise two opposing parallel LEDs, an opposing parallel LED string or an opposing parallel LED matrix. These opposing parallel LEDs may have a capacitor in series connected to at least one junction of the connected opposing parallel configurations within a single chip, a single package, an assembly or a module. 
     When a real capacitor is connected in series in one or more lines between an LED and an AC power source, there is a displacement current through that capacity of magnitude: I=2ΠfCV. The capacitor in the LED circuits of the invention regulates the amount of current and forward voltage delivered to the one or more opposing parallel LEDs based on the voltage and frequency provided by the AC driver. Based on the number of LEDs in the LED circuit the opposing parallel connections provide two or more junctions to which at least one series capacitor may be connected in series of at least one power connection lead. In some embodiments, LED circuits may also use a series resistor in addition to the capacitor providing an “RC” resistor capacitor network for certain LED circuit driver coupling that does not provide protection against surge currents to the LED circuits. 
     According to another aspect of the invention an LED circuit may comprise a single LED or a series string of diodes and/or LEDs connected to a full bridge rectifier capable of rectifying a provided AC voltage and current for use by the series string of diodes and/or LEDs. The rectifier may be formed as part of the LED circuit, or may be formed separately, having leads provided on both the output of the driver and the input of the LED circuit to allow the LED circuit to connect directly to the driver. In order to protect the LED circuit from voltage spikes a capacitor may be connected across the inputs of the bridge rectifier. The capacitor may also be used for smoothing the AC waveform to reduce ripple. A capacitor may likewise be connected between one rectifier input and the AC voltage and current source in order to limit the DC current flow to protect the LEDs. The bridge diode and LED circuit may be packaged separate or together, and may be configured within a single chip or two chips, a single package or two packages, an assembly, or a module. 
     According to another aspect of the invention, a single bridge rectifier may be used to drive parallel LEDs or series strings of diodes and/or LEDs. Alternatively, it is contemplated by the invention that each LED circuit requiring a bridge rectifier to utilize both the high and low phases of an AC power wave may include its own full bridge rectifier integrated or otherwise connected thereto. In embodiments where each LED circuit includes its own rectifier, additional LED circuits may be added in parallel across an AC voltage and current source to any existing LED circuits without concern of connecting to any existing bridge rectifiers or, where used, capacitors. Providing each LED circuit with its own bridge rectifier has the further advantage of scaling capacitors included in the circuit for voltage protection and/or current limiting to be matched to a particular LED or string of diodes and/or LEDs. 
     It should be noted that “package” or “packaged” is defined herein as an integrated unit meant to be used as a discrete component in either of the manufacture, assembly, installation, or modification of an LED lighting device or system. Such a package includes LED&#39;s of desired characteristics with capacitors and or resistors (when used) sized relative to the specifications of the chosen LED&#39;s to which they will be connected in series and with respect to a predetermined AC voltage and frequency. 
     Preferred embodiments of a package may include an insulating substrate whereon the LEDs, capacitors and/or resistors are formed or mounted. In such preferred embodiments of a package, the substrate will include electrodes or leads for uniform connection of the package to a device or system associated with an AC driver or power source or any individually packaged rectifiers used to rectify AC voltage and current. The electrodes, leads, and uniform connection may include any currently known means including mechanical fit, and/or soldering. The substrate may be such as sapphire, silicon carbide, galium nitride, ceramics, printed circuit board material, or other materials for hosting circuit components. 
     A package in certain applications may preferably also include a heat sink, a reflective material, a lens for directing light, phosphor, nano-crystals or other light changing or enhancing substances. In sum, according to one aspect of the invention, the LED circuits and AC drivers of the present invention permit pre-packaging of the LED portion of a lighting system to be used with standardized drivers (and when necessary full wave rectifiers) of known specified voltage and frequency output. Such packages can be of varied make up and can be combined with each other to create desired systems given the scalable and compatible arrangements possible with, and resulting from, the invention. 
     According to one aspect of the invention, AC driven LED circuits (or “driven circuits”) permit or enable lighting systems where LED circuits may be added to or subtracted (either by choice or by way of a failure of a diode) from the driven circuit without significantly affecting the pre-determined desired output range of light from any individual LED and, without the need to: (i) change the value of any discrete component; or, (ii) to add or subtract any discrete components, of any of the pre-existing driven circuit components which remain after the change. During design of a lighting system, one attribute of the LEDs chosen will be the amount of light provided during operation. In this context, it should be understood that depending on the operating parameters of the driver chosen, the stability or range of the voltage and frequency of the driver will vary from the nominal specification based upon various factors including but not limited to, the addition or subtraction of the LED circuits to which it becomes connected or disconnected. Accordingly, as sometimes referred to herein, drivers according to the invention are described as providing “relatively constant” or “fixed” voltage and frequency. The extent of this relative range may be considered in light of the acceptable range of light output desired from the resulting circuit at the before, during, or after a change has been made to the lighting system as a whole. Thus it will be expected that a pre-determined range of desired light output will be determined within which the driven LED circuits of the invention will perform whether or not additional or different LED circuits have been added or taken out of the driven circuit as a whole or whether additional or different LED circuits have been added proximate any existing LED circuits or positioned remotely. 
     According to another aspect of the invention an LED circuit may be at least one pre-packaged LED and one pre-packaged diode connected together opposing parallel of each other, two opposing parallel pre-packaged LEDs, an opposing parallel LED string of pre-packaged LEDs, an opposing parallel LED matrix of pre-packaged LEDs optionally having a capacitor in series of at least one junction of the connected LED circuits. It is contemplated that the LED circuit may also be at least one of a single LED or series string of diodes and/or LEDs having a bridge rectifier connected across the single LED or string of diodes. In embodiments where a series string of diodes and/or LEDs and a rectifier is utilized, each LED may likewise be pre-packaged. The rectifier may optionally having a capacitor connected across the rectifier inputs and/or a capacitor connected between to an input of the rectifier for connection between the rectifier and a AC voltage and current source. In either embodiment, utilizing an LED circuit capacitor may allow for direct coupling of at least one LED circuit to the LED driver without additional series components such as capacitors and/or inductors between the LED circuit driver and the LED circuits. The LED circuit driver provides a relatively fixed voltage and relatively fixed frequency AC output even with changes to the load using feedback AC voltage regulator circuitry. The LED circuit&#39;s may be directly coupled and scaled in quantity to the LED circuit driver without affecting the other LED circuit&#39;s lumen output as long as the LED circuit driver maintains a relatively fixed voltage and relatively fixed frequency AC output. 
     According to an aspect of the invention, an LED circuit driver provides a relatively fixed voltage and relatively fixed frequency AC output such as mains power sources. The LED circuit driver output voltage and frequency delivered to the LED circuit may be higher than, lower than, or equal to mains power voltage and frequencies by using an LED circuit inverter driver. The LED circuit inverter driver providing higher frequencies is preferable for LED circuits that are integrated into small form LED packages that include integrated capacitors or resistor capacitor “RC” networks. The LED circuit inverter driver has feedback circuitry such as a resistor divider network or other means allowing it to sense changes to the load and re-adjust the frequency and/or voltage output of the LED circuit driver to a desired relatively fixed value. The LED circuit driver may also provide a soft-start feature that reduces or eliminates any surge current from being delivered to the LED circuit when the LED circuit driver is turned on. Higher frequency and lower voltage LED circuit inverter drivers are preferred enabling smaller package designs of LED circuits as the capacitor at higher frequencies would be reduced in size making it easier to integrate into a single LED circuit chip, package, assembly or module. 
     According to the invention LED circuits may have a resistor capacitor (“RC”) network connected together in series or separate from the LED circuits. The maximum resistor value needed is only that value of resistance needed to protect the one or more LEDs within the LED circuit from surge currents that may be delivered by LED circuit drivers that do not provide soft start or other anti surge current features. Direct mains power coupling would require RC network type LED circuits as the mains power source delivers surge currents when directly coupled to an LED circuit. 
     The higher frequency LED circuit inverter driver may be a halogen or high intensity discharge (HID) lamp type driver with design modifications for providing a relatively fixed voltage and relatively fixed frequency output as the LED circuit load changes. Meaning if the LED circuit inverter driver is designed to have an output voltage of 12V at a frequency of 50 Khz the LED circuit driver would provide this output as a relatively constant output to a load having one or more than one LED circuits up to the wattage limit of the LED circuit driver even if LED circuits were added to or removed from the output of the LED circuit driver. 
     The higher frequency inverter having a relatively fixed voltage and relatively fixed frequency output allows for smaller components to be used and provides a known output providing a standard reference High Frequency LED circuit driver enabling LED circuits to be manufactured in volume in existing or reasonably similar LED package sizes with integrated capacitors or RC networks based on the number of LEDs desired in the LED circuit package. 
     Patent publication number 20030122502 entitled Light Emitting Diode driver (Clauberg and Erhardt) does not disclose the use of a high frequency inverter driver having a means or keeping a relatively fixed voltage and relatively frequency in response to changes in the load. According to the present invention described herein, by not having additional components such as an inductor or capacitor in series between the LED circuit and the LED circuit driver one LED circuit at a time may be added to or removed from the LED circuit driver output without having to change any components, the LED circuit driver or make adjustments to the LED circuit driver. Additionally, according to this invention the lumen output of the existing LED circuits stays relatively constant due to the self-regulating nature of each individual LED circuit when driven with the relatively fixed frequency and voltage of the LED circuit driver. This level of scalability, single chip LED circuit packaging and standardization is not possible with the prior art using an inductor in series between the LEDs or other components due to the voltage or current increase or drop across the inductors and capacitors in response to changes in the load. 
     Prior art for single chip LED circuits, for example those disclosed in WO2004023568 and JP2004006582 do not provide a way to reduce the number of LEDs within the chip below the total forward voltage drop requirements of the source. The present invention however, enables an LED circuit to be made with any number of LEDs within a single chip, package or module by using, where desired, transformers, capacitors, or RC networks to reduce the number of LEDs needed to as few as one single LED. Improved reliability, integration, product and system scalability and solid state lighting design simplicity may be realized with LED circuits and the LED circuit drivers. Individual LED circuits being the same or different colors, each requiring different forward voltages and currents may be driven from a single source LED circuit driver. Each individual LED circuit can self-regulate current by matching the capacitor or RC network value of the LED circuit to the known relatively fixed voltage and frequency of the LED circuit driver whether the LED circuit driver is a mains power source, a high frequency LED circuit driver or other LED circuit driver capable of providing a relatively fixed voltage and relatively fixed frequency output. 
     When a real capacitor is connected in series in one or more lines between an LED and an AC power source, there is a displacement current through that capacity of magnitude: I=2ΠfCV. This means that one can predetermine the amount of current to be delivered through a capacitance based upon a known voltage and frequency of an AC source, allowing for each LED circuit containing a series capacitor to have the specific or ideal current required to provide the desired amount of light from the LED circuit. 
     According to other aspects of the invention, the LED circuit driver may be coupled to a dimmer switch that regulates voltage or frequency or may have integrated circuitry that allows for adjustability of the otherwise relatively fixed voltage and/or relatively fixed frequency output of the LED circuit driver. The LED circuits get brighter as the voltage and/or frequency of the LED circuit driver output is increased to the LED circuits. 
     One form of the invention is at least one LED and one diode connected together opposing parallel of each other, two opposing parallel LEDs, an opposing parallel LED string and/or opposing parallel LED matrix having a capacitor in series of at least one connected junction of the connected opposing parallel LED configurations within a single chip, a single package, an assembly or a module. When desired, the LED circuit with capacitor may be placed on an insulating substrates such as but not necessarily ceramic or sapphire and/or within various LED package sizes; materials and designs based of product specifications or assembled on printed circuit board material. Any integrated LED circuit capacitors should be scaled to a predetermined value enabling the LED circuit to self-regulate a reasonably constant and specific current when coupled to an LED circuit driver that provides a relatively fixed voltage and frequency output. Utilized LED circuit capacitors may be of a value needed to provide the typical operating voltage and current of the LED circuit when designed for coupling to a specific LED circuit driver. 
     Another form of the invention is an LED circuit comprising at least one LED and one diode connected together opposing parallel of each other, two opposing parallel LEDs, an opposing parallel LED string and/or opposing parallel LED matrix having a series resistor capacitor (“RC”) network connected together in series or independently in series between at least one connected junction of the opposing parallel LEDs and the respective power connection of the LED circuit. When desired, the opposing parallel LEDs and RC network may be placed on an insulating substrate such as but not necessarily ceramic or sapphire and/or within various LED package sizes; materials and designs based of product specifications or assembled on printed circuit board material. The LED circuit RC network may be of a value needed to provide the typical operating voltage and current of the LED circuit when designed for coupling to a specific LED circuit driver. 
     Another form of the invention is an LED circuit comprising a matrix of two opposing parallel LEDs connected together in parallel with every two opposing parallel LEDs having an individual capacitor in series to the power source connection if desired. The entire parallel array of opposing parallel LED circuits, including capacitors when used, may be may be placed on an insulating substrate such as but not necessarily ceramic or sapphire and/or within various LED package sizes; materials and designs based of product specifications or assembled on printed circuit board material. The opposing parallel matrix of LED circuits integrated in the LED circuit package may be RC network type LED circuits. 
     Another form of the invention is an LED circuit comprising a matrix of opposing parallel LEDs connected together in parallel with every set of opposing parallel LEDs having an individual RC network in series to the power connection lead if desired. 
     Another form of the invention is an LED circuit comprising a matrix of opposing parallel LEDs connected together in parallel, a capacitor connected in series to at least one side of the line going to the matrix of opposing parallel LEDs with every set of opposing parallel LEDs having an individual resistor in series to the power connection if desired. 
     Yet another form of the invention is an LED circuit comprising opposing parallel series strings of LEDs connected together and driven direct with a high frequency AC voltage equal to or less than to total series voltage drop of the opposing parallel series strings of LEDs within the LED circuit. 
     Yet another form of the invention is a LED circuit comprising a single LED or a series string of diodes and/or LEDs and a bridge rectifier connected across the LED or string of diodes and/or LEDs. The rectifier may optionally include a capacitor connected across the inputs of the rectifier. The rectifier may additionally, or alternatively, optionally include a capacitor connected in series with one input, the capacitor being capable of connecting the rectifier input to an AC voltage and current source. 
     Yet another form of the invention is a LED circuit comprising a single LEDs or a series strings of diodes and/or LEDs connected in parallel across the output of a bridge rectifier. The rectifier may optionally include a capacitor connected across the inputs of the rectifier. The rectifier may additionally, or alternatively, optionally include a capacitor connected in series with one input, the capacitor being capable of connecting the rectifier input to an AC voltage and current source. 
     Another form of the invention comprises a method of driving LED circuits direct from an AC power source (“LED circuit driver”) having a relatively fixed voltage and relatively fixed frequency. The LED circuit driver may be a mains power source, the output of a transformer, a generator or an inverter driver that provides a relatively fixed voltage and relatively fixed frequency as the load changes and may be a higher or lower frequency than the frequencies of mains power sources. The LED circuit driver provides a relatively fixed voltage and relatively fixed frequency output even when one or more LED circuits are added to or removed from the output of the LED circuit driver. Higher frequency inverters with lower output voltages are used as one LED circuit driver in order to reduce component size and simplify manufacturing and standardization of LED circuits through the availability of higher frequency LED circuit drivers. The LED circuit driver may also include circuitry that reduces or eliminates surge current offering a soft-start feature by using MOSFET transistors, IGBT transistors or other electronic means. The LED circuit driver may also be pulsed outputs at a higher or lower frequency than the primary frequency. 
     Another form of the invention is an LED lighting system comprising an LED circuit array having a plurality of different LED circuits each drawing the same or different currents, each having the same or different forward operating voltages, and each delivering the same or different lumen outputs that may be the same or different colors and an LED circuit driver coupled to the LED circuit array. The LED circuit driver delivering a relatively fixed t frequency and voltage output allows for mixing and matching of LED circuits requiring different forward voltages and drive currents. The LED circuits may be connected to the output of an LED circuit driver in parallel one LED circuit at a time within the limit of the wattage rating of the LED circuit driver with no need to change or adjust the LED circuit driver as would typically be required with DC drivers and LEDs when increasing or reducing the load with LEDs and other components. Never having to go back to the power source allows for more efficient integration and scalability of lighting systems designed with LED circuits and allows for a single driver to independently provide power to multiple independently controlled LED circuits in the system. Introducing an inductor and/or an additional capacitor such as the impedance circuit described in prior art between the LED circuit drive source and the LED circuits would require changes to the driver or components and prohibit scalability, standardization and mass production of AC-LEDs with integrated capacitors or RC networks. 
     With the LED circuit driver providing a known relatively constant AC voltage and frequency, mass production of various LED circuits with specific capacitor or RC network values would deliver 20 mA, 150 mA or 350 mA or any other desired current to the LED circuit based on the output of the specified LED circuit driver. The relatively fixed voltage and frequency allows for standardization of LED circuits through the standardization of LED circuit drivers. 
     In another aspect, a transistor is coupled to at least one power connection of the LED circuit or built into the LED circuit package in series between the power connection lead and the LED circuit with the transistor being operable to control (e.g., varying or diverting) the flow of the alternating current through the LED circuit through a capacitance within the transistor. 
     The foregoing forms as well as other forms, features and advantages of the present invention will become further apparent from the following detailed description of the presently preferred embodiments, read in conjunction with the accompanying drawings. The detailed description and drawings are merely illustrative of the present invention rather than limiting, the scope of the present invention being defined by the appended claims and equivalents thereof. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a schematic view of a preferred embodiment of the invention; 
         FIG. 2  shows a schematic view of a preferred embodiment of the invention; 
         FIG. 3  shows a schematic view of a preferred embodiment of the invention; 
         FIG. 4  shows a schematic view of a preferred embodiment of the invention; 
         FIG. 5  shows a schematic view of a preferred embodiment of the invention; 
         FIG. 6  shows a schematic view of a preferred embodiment of the invention; 
         FIG. 7  shows a schematic view of a preferred embodiment of the invention; 
         FIG. 8  shows a schematic view of a preferred embodiment of the invention; 
         FIG. 9  shows a schematic view of a preferred embodiment of the invention; 
         FIG. 10  shows a schematic view of a preferred embodiment of the invention; 
         FIG. 11  shows a schematic view of a preferred embodiment of the invention; 
         FIG. 12  shows a schematic view of a preferred embodiment of the invention; 
         FIG. 13  shows a schematic view of a preferred embodiment of the invention; 
         FIG. 14  shows a schematic view of a preferred embodiment of the invention; 
         FIG. 15  shows a schematic view of a preferred embodiment of the present invention; 
         FIG. 16  shows a shows a schematic view of a preferred embodiment of the present invention; 
         FIG. 17  shows a schematic view of a preferred embodiment of the present invention; 
         FIG. 18  shows a schematic view of a preferred embodiment of the present invention; 
         FIG. 19  shows a schematic view of a preferred embodiment of the invention; 
         FIG. 20  shows a schematic view of a preferred embodiment of the invention; 
         FIG. 21  shows a schematic view of a preferred embodiment of the invention; 
         FIG. 22  shows a schematic view of a preferred embodiment of the invention; 
         FIG. 23  shows a schematic view of a preferred embodiment of the invention; 
         FIG. 24  shows a schematic view of a preferred embodiment of the present invention; 
         FIG. 25  shows a schematic view of a preferred embodiment of the present invention; 
         FIG. 26  shows a schematic view of a preferred embodiment of the present invention; 
         FIG. 27  shows a schematic view of a preferred embodiment of the present invention; 
         FIG. 28  shows a schematic view of a preferred embodiment of the present invention; 
         FIG. 29  shows a schematic view of a preferred embodiment of the invention; 
         FIG. 30A  shows a schematic view of a preferred embodiment of the invention; 
         FIG. 30B  shows a schematic view of a preferred embodiment of the invention; 
         FIG. 30C  shows a schematic view of a preferred embodiment of the invention; 
         FIG. 30D  shows a schematic view of a preferred embodiment of the invention; 
         FIG. 30E  shows a schematic view of a preferred embodiment of the invention; 
         FIG. 31  shows a schematic view of a preferred embodiment of the invention; 
         FIG. 32  shows a schematic view of a preferred embodiment of the invention; 
         FIG. 33  shows a schematic view of a preferred embodiment of the invention; 
         FIG. 34  shows a schematic view of a preferred embodiment of the invention; 
         FIG. 35  shows a schematic view of a preferred embodiment of the invention; and, 
         FIG. 36  shows a schematic view of a preferred embodiment of the invention; 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     While this invention is susceptible to embodiments in many different forms, there is described in detail herein, preferred embodiments of the invention with the understanding that the present disclosures are to be considered as exemplifications of the principles of the invention and are not intended to limit the broad aspects of the invention to the embodiments illustrated. 
     The present invention is directed to an LED light emitting device and LED light system capable of operating during both the positive and negative phase of an AC power supply. In order to operate during both phases provided by an AC power, as is shown herein, the circuit must allow current to flow during both the positive and negative phases and LED light emitting devices may be configured such that at least one LED is capable of emitting light during one or both of the positive or negative phases. In order to accomplish this, the LED circuit itself may be configured so as to allow current to pass during both phases, or the device may include a bridge rectifier to rectify AC power for use by single LEDs, series strings of LEDs, and parallel series strings of LEDs. Rectification may be accomplished within the light emitting device, or prior to any power being provided to the same. Once integrated into a light system, the present invention further contemplates a driver having the ability to provide a substantially constant voltage at a substantially constant frequency, and that the driver be configured in a manner which will allow LED light emitting devices to be added to or subtracted from the system, regardless of configuration, without having to add, subtract, or change the values of discrete circuit components and without affecting the light output of any individual LED. 
       FIG. 1  discloses a schematic diagram of a light emitting device  10  for an AC driver according to one embodiment of the invention. The device  10  includes a first LED  12  connected to a second LED  14  in opposing parallel configuration, a capacitor  16  connected in series between a first junction  18  of the two opposing parallel LEDs, a first power connection  20  connected to the two opposing parallel LEDs, and a second power connection  22  connected to a second junction  24  of the two opposing parallel connected LEDs. A diode may be used in place of LED  12  or LED  14 . 
       FIG. 2  discloses a schematic diagram of a light emitting device  26  for an LED circuit driver according to an embodiment of the invention. The device  26  includes the device  10  as disclosed in  FIG. 1  mounted on an insulating substrate  28  such as, but not necessarily, ceramic or sapphire, and integrated into an LED package  30  that may be various LED package sizes; materials and designs based of product specifications or on printed circuit board material. The device  26  provides power connection leads  32  and may have a first or additional lens  34  that may be made of a plastic, polymer or other material used for light dispersion and the lens may be coated or doped with a phosphor or nano-particle that would produce a change in the color or quality of light emitted from the device  10  through the lens  34 . 
       FIG. 3  discloses a schematic diagram of a device  36  having a schematic diagram of the embodiment shown as light emitting device  26  driven directly by an AC driver  38  that is connected to the power connections  32  of the device  26  without any additional components in series between the AC driver  38  and the device  26  such as a capacitor, inductor or resistor. The AC driver  38  provides a relatively constant AC voltage and frequency output to the device  26  no matter what the total load of the device  26  may be, or the number of devices  26  added or subtracted as long as the load does not exceed the wattage limitation of the AC driver  38 . The AC driver  38  may be a generator, a mains power source, or an inverter capable of providing a relatively fixed voltage and relatively fixed frequency output to different size loads. The AC driver may provide a low or high voltage and a low or high frequency to the device  26  according to the invention as long as the capacitor  16  is the proper value for the desired operation of the device  26 . 
       FIG. 4  discloses a schematic diagram of a light emitting device  40  for coupling to an LED circuit driver according to an embodiment of the invention. The device  40  includes a first LED  42  connected to a second LED  44  in opposing parallel configuration. A capacitor  46  is connected in series between a first junction  48  of the two opposing parallel LEDs and a first power connection  50 . A resistor  52  is connected in series between a second junction  54  of the two opposing parallel LEDs and a second power connection  56 . A diode may be used in place of LED  42  or LED  44  and the resistor  52  may be put in series on either end of the capacitor  46  as an alternate location. 
       FIG. 5  discloses a schematic diagram of a light emitting device  58  for LED circuit drivers according to an embodiment of the invention. The device  58  includes the device  40  as disclosed in  FIG. 4  integrated into a package as disclosed in the device  26  in  FIG. 2 . The device  58  provides power connection leads for connecting to an AC driver  38  as disclosed in  FIG. 3 . 
       FIG. 6  discloses a diagram of a light emitting device  64  for coupling to an LED circuit driver according to an embodiment of the invention. The device  64  includes a first series string of LEDs  66  connected to a second series string of LEDs  68  in opposing parallel configuration, a capacitor  70  connected in series between a first junction  72  of the opposing parallel series string of LEDs and a first power connection  74 , and a second power connection  76  connected to a second junction  78  of the opposing parallel series string of LEDs. A diode may be used in place of one or more LEDs  66  and one or more of LEDs  68  and the LEDs  66  and  68  are integrated into a package  80  as described in the package  30  disclosed in  FIG. 2  along with capacitor  70 . 
       FIG. 7  discloses a diagram of a light emitting device  82  for AC drive according to an embodiment of the invention. The device  82  includes a first series string of LEDs  84  connected to a second series string of LEDs  86  in opposing parallel configuration, a capacitor  88  connected in series between a first junction  90  of the opposing parallel series string of LEDs and a first power connection  92 , and a resistor  94  connected in series between a second junction  96  of the opposing parallel series string of LEDs and a second power connection  98 . A diode may be used in place of one or more LEDs  84  and one or more of LEDs  86  and the LEDs  84  and  86  are integrated into a package  100  as described in the package  30  disclosed in  FIG. 2  along with capacitor  88  and resistor  94 . The resistor  94  may be put in series on either end of the capacitor  88  as an alternate location. 
       FIG. 8  discloses a diagram of a light emitting device  102  according to an embodiment of the invention. The device  102  includes a first series string of LEDs  104  connected to a second series string of LEDs  106  in opposing parallel configuration. A first power connection  108  is connected to a first junction  110  of the opposing parallel series string of LEDs and a second power connection  112  is connected to a second junction  114  of the opposing parallel series string of LEDs. A diode may be used in place of one or more LEDs  104  and one or more of LEDs  106  and the LEDs  104  and  106  are integrated into a package  118  as described in the package  30  disclosed in  FIG. 2 . 
       FIG. 9  discloses a circuit diagram of a light emitting device  120  according to an embodiment of the invention. The device  120  is similar to the device disclosed in  FIG. 5  and includes a second series resistor  122  that can be placed in series on either side of the first capacitor  46 . 
       FIG. 10  discloses a diagram of a light emitting device  124  according to an embodiment of the invention. The device  124  is similar to the device disclosed in  FIG. 2  and includes a second series capacitor  126  connected in series between the junction  128  of the opposing parallel LEDs and a power connection  130 . 
       FIG. 11  discloses a diagram of a light emitting device  130  according to an embodiment of the invention. The device  130  has a matrix of individual light emitting devices  10  as described in  FIG. 1  integrated into a package  132  similar to package  30  as described in  FIG. 2 . 
       FIG. 12  discloses a diagram of a light emitting device  134  according to an embodiment of the invention. The device  134  has a matrix of individual light emitting devices  40  as described in  FIG. 4  integrated into a package  136  similar to package  30  as described in  FIG. 2 . 
       FIG. 13  discloses a diagram of a light emitting device  138  according to an embodiment of the invention. The device  138  has a matrix of individual sets of 2 opposing parallel light emitting devices  140  with each set having an individual series resistor to connect to a first power connection  140  and a capacitor  146  connected in series between a second power connection and the matrix of devices  140 . The capacitor  146  may alternately be in series between the first power connection  144  and all resistors  142 . The matrix of devices  140 , resistors  142  and capacitor  146  are integrated into a package  150  similar to package  30  as described in  FIG. 2 . 
       FIG. 14  discloses a diagram of a light emitting device  152  according to an embodiment of the invention. The device  152  includes another version of a series opposing parallel LED matrix  154  and a capacitor  156  connected in series between a first junction  158  of the opposing parallel LED matrix  154  and a first power connection, and a second power connection  162  connected to a second junction  164  of the opposing parallel LED matrix. A first power connection  108  is connected to a first junction  110  of the opposing parallel series string of LEDs and a second power connection  112  is connected to a second junction  114  of the opposing parallel series string of LEDs. A diode may be used in place of one or more LEDs  104  and one or more of LEDs  106  and the LEDs  104  and  106  are integrated into a package  118  as described in the package  30  disclosed in  FIG. 2 . 
       FIG. 15  discloses a schematic diagram of a light emitting device  300  according to an embodiment of the invention. Device  300  includes bridge rectifier circuit  302  having diodes  304   a - 304   d  with at least one LED connected across the output of the rectifier circuit, shown as LED  306 . While inputs  308  and  310  of the bridge rectifier may be provided for direct connection to an AC power supply, it is contemplated by the invention that one input, shown as input  310 , may have a capacitor (shown as capacitor  312 ) or a resistor (shown in  FIG. 18  as resistor  313 ) connected in series in order to control and limit the current passing through the at least one LED. Additionally, capacitor  314  may be connected across the rectifier inputs to protect against voltage spikes. 
       FIGS. 16 and 18  each disclose a schematic diagram of a light emitting device  316  and  332  for an LED circuit driver according to an embodiment of the invention. The device  316  includes the device  300  as disclosed in  FIG. 15  (with additional LEDs  306  added in series) mounted on an insulating substrate  318  such as, but not necessarily, ceramic or sapphire, and forming an LED package  320  that may be various sizes; materials and designs based of product specifications or on printed circuit board material. As shown in  FIG. 16 , The device  316 ,  332  provides power connection leads  322  and  323  and may have a first or additional lens that may be made of a plastic, polymer or other material used for light dispersion and the lens may be coated or doped with a phosphor or nano-particle that would produce a change in the color or quality of light emitted from device  300  through the lens, LED package  320  may include rectifier  302  to drive LEDs  306 . Rectifier  306  may be mounted on insulating substrate  318  along with any LEDs. As should be appreciated by those having ordinary skill in the art, it is contemplated by the invention that any diode or LED may be swapped for the other within the package so long as the package includes at least one LED to emit light when in operation. Any capacitors  312 ,  314  or resistors  313  included in the light emitting devices may like wise be mounted on substrate  318  and included in LED package  320 . 
     Rather than be packaged together and mounted on a single substrate, and no matter whether the LEDs and diodes are integrated into a single package or are discrete individual LEDs and/or diodes wire-bonded together, as disclosed in  FIG. 17  rectifier  302  may be discretely packaged separate from any discrete LED packages  324  where discrete LED package  324  includes one LED  306  or multiple LEDs connected in series or parallel. Rectifier  302  may be packaged into rectifier package  326  for plug and use into a light system, or alternatively may be included as part of a driver used to drive the series LEDs. When packaged separate, package  326  may be provided with input power connections  328  and  329  which to connect the inputs of the rectifier to an AC power supply. In order to connect to one (or more) single or series LEDs and provide power thereto, package  326  may also be provided with output power connections  330  and  331  which may connect to LED package inputs  334  and  335 . Any capacitors  312 ,  314  or resistors  313  included in the light emitting devices may like wise be mounted on substrate  316  and included in rectifier package  326 . 
     Regardless of whether rectifier  302  and LEDs  306  are integrated or mounted in a single package or are discretely packaged and connected, in order to drop higher voltages any number of LEDs may be connected in series or parallel in a device to match a desired voltage and light output. For example, in a lighting device that is run off of a 120 V source and contains LEDs having a forward operating voltage of 3V each connected to a bridge rectifier having diodes also having a forward operating voltage of 3V each, approximately 38 LEDs may be placed in series to drop the required voltage. 
       FIG. 19  discloses an embodiment of an LED lighting device encapsulated in a housing. As shown in  FIG. 19 , LED device  336  may include a housing  338  encapsulating at least one bridge rectifier  340 , at least one LED circuit  342  connected across the output of the bridge rectifier. Device  334  includes first power connection lead connected  344  to a first input of the rectifier  346  and a second power connection lead  348  connected to a second input of the rectifier  350 . At least a portion of each power connection is contained within the housing while at least a portion of each power connection extends beyond the housing to allow device  336  to connect to an AC power source. Rectifier  340  and LED circuit  342  may be connected, assembled, and/or packaged within housing  336  using any of the methods described in conjunction with  FIGS. 15-18  or any other means known in the art. It should be appreciated by those having ordinary skill in the art that the devices and packages described in  FIGS. 2 ,  3 , and  5 - 14  may likewise incorporate a housing to encapsulate any device and/or package therein. 
       FIG. 20  discloses a schematic diagram of a lighting system  168  according to an embodiment of the invention. The device  168  includes a plurality of devices  26  as described in  FIG. 2  connected to a high frequency inverter AC drive Method  170  as described in  FIG. 3  which in this example provides a relatively constant 12V AC source at a relatively constant frequency of 50 Khz to the devices  26 . Each or some of the devices  26  may have integrated capacitors  172  of equal or different values enabling the devices  26  to operate at different drive currents  174  from a single source AC drive Method. 
       FIG. 21  discloses a schematic diagram of a lighting system  176  according to an embodiment of the invention. The lighting system  176  includes a plurality of devices  178 ,  180  and  182  each able to have operate at different currents and lumens output while connected directly to the transformer  184  output of a fixed high frequency AC drive Method  186 . 
     Any of the aforementioned AC drive methods may likewise be used with the devices embodied in  FIGS. 15-19 . 
     For example,  FIG. 22  discloses a schematic diagram of a lighting system  400  according to an embodiment of the invention. System  400  includes a plurality of devices  316 ,  332  as described in  FIGS. 16 and 18  connected to a high frequency inverter AC drive Method  170  similar to that described in  FIGS. 3 and 20  which provides a relatively constant 12V AC source at a relatively constant frequency of 50 Khz to the devices  316 ,  332 . Each or some of the devices  316 ,  332  may have integrated capacitors  312 ,  314  and resistors  313  of equal or different values enabling the devices  300  to operate at different drive currents from a single source AC drive Method. As should be appreciated by those having ordinary skill in the art, while the example of 12V AC at 50 Khz is given herein, it is contemplated by the invention that any voltage at substantially any frequency may be provided by the driver by utilizing a proper transformer and/or inverter circuit. 
     Similarly, AC drive Method  186  may be utilized may be used with a single or plurality of devices  214  as disclosed in  FIG. 23 . As with the embodiment shown in  FIG. 21 , each device  316 ,  332  may be connected directly to transformer  184  output to receive a substantially fixed frequency voltage. 
       FIG. 24  discloses an embodiment of the invention where AC drive Method  186  is provided to a rectifier and LED series strings are discretely packaged. As previously disclosed, rectifier  302  may be discretely packaged in a rectifier package  326 , separate from both AC drive Method  186  (or alternatively AC drive Method  170 ) and discrete LED packages  324 , or alternatively may be included in AC drive Method  186 . 
       FIG. 25  discloses another schematic view diagram of a light emitting device  188  identical to the device  130  disclosed in  FIG. 11  and integrated into a package  30  as described in  FIG. 2  for an AC drive Method according to an embodiment of the invention. The device  188  includes the device  130  as disclosed in  FIG. 11  mounted on an insulating substrate  28  such as but not necessarily ceramic or sapphire and integrated into an LED package  30  that may be various LED package sizes; materials and designs based of product specifications or on printed circuit board material. The device  188  provides power connection leads  190  and  192  and may have a first or additional lens  194  that may be made of a plastic, polymer or other material used for light dispersion and the lens may be coated or doped with a phosphor or nano-crystals that would produce a change in the color or quality of light emitted from the device  130  through the lens  194 . The device  130  has a matrix of devices  10 . The power connection opposite the capacitors  16  within the device  130  and part of each device  10  is connected to a power connection  196  that is connected to a solderable heat sinking material  198  and integrated into the package  30 . The power connection  196  connected to the heat sink  198  may be of a heavier gauge within the device  130  or  188  than other conductors. The schematic view of the device  188  provides a side view of the package  30  and an overhead view of the device  130  in this  FIG. 25 . 
       FIG. 26  discloses another schematic view diagram of a light emitting device  198  similar to the device  188  described in  FIG. 25  with a different light emitting device  200  identical to the device  136  disclosed in  FIG. 12  and integrated into a package  30  as described in  FIG. 2  for an AC drive Method according to an embodiment of the invention. The device  198  includes a reflective device integrated into the package  30  for optimized light dispersion. The light emitting device  200  may be facing down towards the reflector  202  and opposite direction of light output from the lens  194  if the reflector  202  is integrated into the package  30  properly for such a design. 
       FIG. 27  discloses another schematic view diagram of a light emitting device  500  similar to that shown in  FIG. 24  according to an embodiment of the invention. The device  500  includes the devices  316 ,  332  similar to those disclosed in  FIGS. 16 and 18 , mounted on an insulating substrate  318  such as but not necessarily ceramic or sapphire and integrated into an LED package  320  that may be various LED package sizes; materials and designs based of product specifications or on printed circuit board material. The device  500  provides power connection leads  502  and  503  which connect to package power connect leads  322  and  323  and may have a first or additional lens  504  that may be made of a plastic, polymer or other material used for light dispersion and the lens may be coated or doped with a phosphor or nano-crystals that would produce a change in the color or quality of light emitted from the device through the lens  504 . Power connection  322  may be connected to heat sink  506  and may be of a heavier gauge within the device than other conductors. 
       FIG. 28  discloses another schematic view diagram of a light emitting device  508  similar to that shown in  FIG. 26 . Device  508  is contemplated for use in embodiments where the rectifier is discretely packaged or included as part of AC drive Method  170  or  186 . In device  508 , power connection leads  510  and  511  connect to the outputs of rectifier  302  (not shown) to provide power to LED packages  324 . 
       FIG. 29  shows a block diagram of an LED circuit driver  204  having a high frequency inverter  206  stage that provides a relatively constant voltage and relatively constant frequency output. The high frequency inverter  206  stage has an internal dual half bridge driver with an internal or external voltage controlled oscillator that can be set to a voltage that fixes the frequency. A resistor or center tapped series resistor diode network within the high frequency inverter  206  stage feeds back a voltage signal to the set terminal input of the oscillator. An AC regulator  208  senses changes to the load at the output lines  210  and  212  of the inverter  206  and feeds back a voltage signal to the inverter  208  in response changes in the load which makes adjustments accordingly to maintain a relatively constant voltage output with the relatively constant frequency output. 
       FIG. 30  shows a schematic diagram of an LED circuit driver  214  having a voltage source stage  216 , a fixed/adjustable frequency stage  218 , an AC voltage regulator and measurement stage  220 , an AC level response control stage  222 , an AC regulator output control stage  224  and a driver output stage  226 . 
       FIG. 31  shows a schematic diagram of the voltage source stage  216  described in  FIG. 20 . The voltage source stage  216  provides universal AC mains inputs  228  that drive a diode bridge  230  used to deliver DC to the LED circuit driver system  214 . Direct DC could eliminate the need for the universal AC input  228 . Power factor correction means  232  may be integrated into the LED circuit driver  216  as part of the circuit. The voltage source stage  216  includes a low voltage source circuit  234  that may include more than one voltage and polarity. 
       FIG. 32  shows a schematic diagram of the fixed/adjustable frequency stage  218  as described in  FIG. 20 . The fixed/adjustable frequency stage  218  includes a bridge driver  236  that may include an integrated or external voltage controlled oscillator  238 . The oscillator  238  has a set input pin  240  that sets the frequency of the oscillator to a fixed frequency through the use of a resistor or adjustable resistor  242  to ground. The adjustable resistor  242  allows for adjusting the fixed frequency to a different desired value through manual or digital control but keeps the frequency relatively constant based on the voltage at the set terminal  240 . 
       FIG. 33  is a schematic diagram of the AC voltage regulator with voltage measurement stage  220  as described in  FIG. 20 . The AC voltage regulator with voltage measurement circuit  220  monitors the voltage at the driver output  226  as shown in  FIG. 20  and sends a voltage level signal to the AC level response control stage  222  as shown in  FIG. 20 . 
       FIG. 34  is a schematic diagram of the AC level response control  228  stage. The AC level response control stage  228  receives a voltage level signal from the AC voltage regulator with voltage measurement circuit  220  as shown in  FIG. 23  and drives the AC regulator output control stage  224  as shown in  FIG. 20 . 
       FIG. 35  is a schematic diagram of the AC regulator output control stage  230 . The AC regulator output control stage  230  varies the resistance between the junction of the drive transistors  232  and the transformer input pin  234  of the driver output  226  as shown in  FIG. 26 . The AC regulator output control stage  230  is a circuit or component such as but not necessarily a transistor, a voltage dependent resistor or a current dependent resistor circuit having a means of varying its resistance in response to the voltage or current delivered to it. 
       FIG. 36  is a schematic diagram of the driver output stage  226 . The driver output stage  226  includes drive transistors  232  and the transformer  236  that delivers an AC voltage output  238  to LED circuits at a relatively constant voltage and frequency. 
     The above-described embodiments of the present invention are intended to be examples only. Alterations, modifications and variations may be effected to the particular embodiments by those of ordinary skill in the art without departing from the scope of the invention, which is defined by the claims appended hereto.