AC LED ASSEMBLY AND LIGHTING SYSTEM METHOD AND APPARATUS
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`RELATED APPLICATIONS
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`[Para 1]
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`The present application claims priority to U.S. Provisional Application No.
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`60/547,653, filed February 25, 2005 and U.S. Provisional Application No. 60/559,867, filed
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`April6, 2004, both of which are incorporated herein by reference.
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`TECHNICAL FIELD
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`[Para 2]
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`The present invention generally relates to light emitting diodes ("LEDs") and
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`LED drive methods. The present invention specifically relates to AC LED assemblies and AC
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`LED assembly lighting systems.
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`FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
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`[Para 3]
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`None.
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`BACKGROUND OF THE INVENTION
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`[Para 4]
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`LEDs are semiconductor devices that produce light when a current is supplied to
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`them. LEDs are intrinsically DC devices that only pass current in one polarity and historically
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`have been driven by DC voltage sources using resistors, current regulators and voltage regulators
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`to limit the voltage and current delivered to the LED. Some LEDs have resistors built into the
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`LED package providing a higher voltage LED typically driven with 5V DC or 12V DC.
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`[Para 5]
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`With proper design considerations LEDs may be driven more efficiently with AC
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`than with DC drive schemes. LED based lighting may be used for general lighting, specialty
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`lighting, signs and decoration such as for Christmas tree lighting. For example, U.S. Pat. No.
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`5,495,147 entitled LED LIGHT STRING SYSTEM to Lanzisera (hereinafter "Lanzisera") and
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`U.S. Pat. No. 4,984,999 entitled STRING OF LIGHTS SPECIFICATION to Leake (hereinafter
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`"Leake") describes different forms of LED based light strings. In both Lanzisera and Leake,
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`exemplary light strings are described employing purely parallel wiring of discrete LED lamps
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`using a step-down transformer and rectifier power conversion scheme. This type of LED light
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`string converts input electrical power, usually assumed to be the common U.S. household power
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`of 110 V AC, to a low voltage, rectified to nearly DC input.
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`1
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`IPR PAGE 1
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`[Para 6)
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`LEDs can be operated from an AC source more efficiently if they are ~onnected
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`in an "opposing parallel" configuration.
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`[Para 7]
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`Pat. Pending Application No. 0015968Al entitled PREFERRED EMBODIMENT
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`TO LED LIGHT STRING to Allen (hereinafter "Allen") discloses AC powered LED-based light
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`strings. Allen describes LED light strings employing series parallel blocks with a voltage
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`matching requirement for direct AC drive placing fundamental restrictions on the number of
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`diodes (LEDs) on each diode series block, depending on the types of diodes used. Allen
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`discloses that for the forward voltage to be "matched," in each series block, the peak input
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`voltage must be less than or equal to the sum of the maximum forward voltages for each series
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`block in order to prevent over-driving.
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`[Para 8]
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`(Para 9]
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`LED~ driven with 50/60 Hz AC are known to flicker. A true AC LED circuit has
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`LEDs connected in opposing parallel configuration so that one each half cycle of the AC
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`waveform powers one half the LED circuit causing the LEDs to take turns thus causing flicker.
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`[Para 10)
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`One way to reduce flicker is to increase the frequency of the AC waveform ans
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`taught by Clauberg patent # -------and Miskin patent application number----------- .
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`[Para 11]
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`LED semiconductor die have been integrated into LED packages and configured
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`into AC LED circuits within an LED device and/or package as thought by Seoul patent
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`#
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`and Miskin patent #
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`. These LEDs
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`are configured in anti-parallel configuration at the semiconductor level.
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`[Para 12]
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`The density of the LED die placement in these AC LED packages can reduce
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`and/or eliminate flicker when powered with low frequency AC such as the 50/60 Hz mains
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`voltage enables these LEDs to be powered with low frequency AC voltages at frequencies of
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`50/60 Hz as provided by mains power .sources.
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`[Para 13)
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`Handling and packaging LED semiconductor die requires special facilities,
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`equipment and professional staff. The capital investment needed to acquire and/or build these
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`resources places limits on the availability of AC LED technology that can operate on lower
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`frequency AC voltages such as the 50/60 Hz mains.
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`[Para 14]
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`The present invention addresses the above-noted shortcomings of the prior art
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`while providing new methods of packaging AC LED technology that can be driven at low
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`frequency AC voltages thereby offering benefits and advantages over prior art.
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`2
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`IPR PAGE 2
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`[Para 15]
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`It would be advantageous to be able to manufacture AC LED assemblies that can
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`operate on low frequency AC voltages without having to use packaged AC LED devices.
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`[Para 16]
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`It would be advantageous to be able to manufacture AC LED assemblies that can
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`operate on low frequency AC voltages without having to integrate and package the raw
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`semiconductor LED die within a LED semiconductor packages more easily.
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`[Para 17]
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`It would be advantageous to be able to manufacture AC LED products that can
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`operate on low frequency AC voltages such as the mains power source more cost effectively and
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`without having to acquire all the resources needed to package raw semiconductor LED die.
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`[Para 18]
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`It would be advantageous to be able to operate these AC LED assemblies over
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`low frequency AC voltages sources such as direct mains 120/220Vac and/or lower AC voltages
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`such as 12Vac or 24Vac provided through step down magnetic transformers.
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`SUMMARY OF THE INVENTION
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`[Para 19]
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`AC LED assemblies can be designed and manufactured without packaged AC
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`LED devices and operate on low frequency AC voltages without producing low frequency
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`flick~r effects by utilizing very small prepackaged LEDs that can be placed onto a printed circuit
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`board assembly at a spatial separation that is dense enough to cause the flicker to be reduced
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`and/or eliminated by virtue of the eye integrating the light distributed by the AC LED assembly
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`at low frequencies.
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`[Para 20]
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`It is also contemplated that the light distributed from such an AC LED assembly
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`would cause photons and /or light beams to cross paths based on the light distribution and/or
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`viewing angle of the prepackaged LEDs being used in the AC LED assembly thereby integrating
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`distributed light and reducing the effects of flicker at low frequency AC voltage.
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`[Para 21]
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`According to one broad aspect of the invention a LED assembly is provided
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`having one or more LED circuits. Each LED circuit has at least two packaged LEDs connected
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`to each other in opposing parallel relation at a special separation less than 3 mm. The at least two
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`LEDs are of a dimension less than 2.5mm x 2.5 mm. The AC LED circuit may be also be
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`comprised ofLEDs configured in anti-parallel and cross connected between opposing phases so
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`that the opposing sides of the anti-parallel LEDs are forward biased at both half cycles of an AC
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`wave so that many ofthe LEDs are on during both half cycles of an AC wave.
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`3
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`IPR PAGE 3
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`Claims:
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`I. An AC LED assembly comprising:
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`At least two packaged LEDs having a dimension less than 2.5mm x 2.5mm in
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`size,
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`a thermally conductive printed circuit board,
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`the at least two packaged LEDs being mounted onto the thermally conductive
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`printed circuit board
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`the at least two packaged LEDs placed on the thermally conductive printed
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`circuit board at a special separation that is less than 3mm between the at least
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`twoLEDs.
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`2. The AC LED assembly of claim I being connected to a low frequency AC
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`power source.
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`3. The AC LED assembly of claim I having LEDs with a light distribution
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`viewing angle that is broad enough to cause the light beam or distribution of
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`one LED to cross the path of the LED next to it.
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`4. The AC LED assembly of claim I configured such that it can be powered with
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`a high frequency low voltage AC electronic transformer.
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`5. The AC LED assembly of claim I configured such that it can be configured
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`such that it can be powered by a magnetic transformer
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`6. The method of manufacturing the AC LED assembly of claim one as an
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`independent circuit.
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`7. The method of manufacturing the AC LED assembly of claim 1 in a printed
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`circuit board panel.
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`8. The method of claims 1 and 7 having more than one of the AC LED
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`assemblies of claim I electrically connected to at least one other AC LED
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`assemblies on the same printed circuit board panel.
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`4
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