Apparatus and method for bypassing failed LEDS in lighting arrays
First Claim
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1. A method for operating a solid state light source which receives current from a current-controlled source having an available unloaded voltage along a primary current path comprising:
- a. providing an alternate current path around the solid state light source;
b. holding the alternative current path inactive over a range of ambient temperatures and operating conditions so long as a condition indicative of an open solid state light source failure is not sensed;
c. activating the alternate current path upon detecting a condition indicative of an open solid state light source failure, and setting a triggering voltage associated with the condition without requiring the trigger voltage for the alternate current path needed over the temperature range to exceed the available unloaded voltage of the source.
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Abstract
An apparatus, method and system for controlling one or multiple lighting sources such as those powered by driver circuits or voltage splitting methods, to provide an alternative current path around a failed lighting source when one or more individual lighting sources fail.
36 Citations
21 Claims
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1. A method for operating a solid state light source which receives current from a current-controlled source having an available unloaded voltage along a primary current path comprising:
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a. providing an alternate current path around the solid state light source; b. holding the alternative current path inactive over a range of ambient temperatures and operating conditions so long as a condition indicative of an open solid state light source failure is not sensed; c. activating the alternate current path upon detecting a condition indicative of an open solid state light source failure, and setting a triggering voltage associated with the condition without requiring the trigger voltage for the alternate current path needed over the temperature range to exceed the available unloaded voltage of the source. - View Dependent Claims (2, 3, 4, 6, 7, 8, 9, 10)
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5. The method of claim further comprising providing said current with a current driver circuit.
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11. An LED lighting apparatus comprising:
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a. a string of a plurality of LED light sources connected in series and having an operating current from a current-controlled driver having a voltage limit along a primary current path; b. an alternative current path circuit placed in parallel with the string of LEDs, the alternative current path circuit including a transistor circuit wherein; i. the transistor circuit is substantially inactive except for conducting small leakage and bias currents in a first state; ii. the transistor circuit becomes automatically active to pass at least substantially most of the operating current in a second state; c. wherein the first state is indicative of normal operation of the string of LEDs and the second state is indicative of an. open failure of at least one LED in the string of LEDs; d. wherein the determination of the existence of the first or second states is calibrated to prevent false selection of the second state over a range of ambient temperatures and operating conditions; and e. wherein the selection of the second state does not exceed the voltage limit of the current-controlled driver. - View Dependent Claims (12, 13, 14, 15, 16)
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17. A method of designing an alternative current path circuit adapted for placement in parallel with an LED or string of LEDs to be essentially inactive until a condition indicative of an open LED failure is sensed, and then automatically becoming active to bypass that LED or the string of LEDs including that LED, with substantially all the operating current from a current-controlled driver having an available open circuit voltage maximum, method comprising:
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a. determining and setting a triggering voltage for automatic triggering of an active state for the circuit; b. wherein the triggering voltage is calibrated to prevent false triggering over a range of ambient temperatures and operating conditions; and c. wherein the triggering voltage is calibrated to allow triggering within the available open circuit voltage maximum for the current-controlled driver. - View Dependent Claims (18, 19, 20)
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21. A method of designing an alternative current path circuit adapted for placement in parallel with an LED or string of LEDs to be essentially inactive until a condition indicative of an open LED failure is sensed, and then automatically becoming active to bypass that LED or the string of LEDs including that LED, with substantially all the operating current, the method comprising:
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a. determining and setting a triggering voltage for automatic triggering of an active state for the circuit; b. wherein the automatic triggering comprises a shunt circuit that is latched to an on state; c. further comprising preventing false triggering by filtering transients and triggering voltage is compensated for temperature effects.
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Specification