LED DEVICE AND LED DRIVER
First Claim
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1. An LED driver for driving one or plural LEDs (light emitting diodes) connected in series with each other electrically to emit light, comprising:
- a DC power source that outputs a DC LED driving voltage;
a constant current driving circuit connected in series with said LED with respect to said DC power source for providing a constant LED driving current in said LED; and
a headroom voltage monitoring circuit for said DC power source to perform dynamic variable control of the voltage level of said LED driving voltage so that the headroom voltage obtained at the current terminal of said constant current driving circuit is kept within a predetermined range of a first reference voltage.
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Abstract
A LED device having a LED array, LED driver ICs, DC-DC converter, a first feedback circuit consisting of voltage dividing resistors, and a headroom voltage monitoring circuit having controller and second feedback circuit. In second feedback circuit, headroom voltages obtained at output current terminals of the LED driver ICs, are fed back to DC-DC converter.
68 Citations
20 Claims
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1. An LED driver for driving one or plural LEDs (light emitting diodes) connected in series with each other electrically to emit light, comprising:
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a DC power source that outputs a DC LED driving voltage; a constant current driving circuit connected in series with said LED with respect to said DC power source for providing a constant LED driving current in said LED; and a headroom voltage monitoring circuit for said DC power source to perform dynamic variable control of the voltage level of said LED driving voltage so that the headroom voltage obtained at the current terminal of said constant current driving circuit is kept within a predetermined range of a first reference voltage. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 19)
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9. An LED driver comprising:
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a DC power source that outputs a DC LED driving current; an LED array having m LED serial circuits (m is an integer of 2 or greater), each having n LEDs (n is an integer of 2 or greater) electrically connected in series, electrically connected in parallel with respect to the output terminal of said DC power source; m constant current driving circuits for providing a constant LED driving current in said LEDs and connected in series with said m LED serial circuits with respect to said DC power source; and a headroom voltage monitoring circuit for said DC power source and dynamically variably controls the voltage level of said LED driving voltage so that at least one of the headroom voltages obtained at the current terminals of said m constant current driving circuits is kept within a predetermined range of a first reference voltage. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17, 18, 20)
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Specification