Lighting control device
First Claim
1. A lighting device comprising:
- a cluster of WLEDs, at least some of which WLEDs are chained in parallel between a pair of lines that apply a voltage across the WLED chains;
first current altering means that can be controlled to alter the total current delivered to the individual WLED chains;
second current altering means provided in each WLED chain, the second current altering means being controllable to alter the current flow in that WLED chain;
current measuring means in each WLED chain; and
control means communicating with the current measuring means within in each WLED chain, the control means being capable of controlling at least one of (i) the first current altering means and (ii) at least one of the second current altering means in response to variations in measured current in the individual WLED chains.
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Accused Products
Abstract
A lighting device and control means therefor is disclosed. The lighting device consists of a plurality of White LEDs (WLEDs) provided in separate chains all connected parallel. A small number of WLEDs is connected in series in each chain, and a number of such chains are wired together in parallel between a pair of voltage lines from which current is drawn. Current measurement and adjusting means is provided firstly between a high voltage line and all the parallely connected chains, and secondly in each chain. Each current measurement and adjusting means is controlled ideally by a microprocessor which monitors both the total current drawn by all the chains together and also the individual currents flowing in each chain. WLEDs have a tendency to fail when subjected to sudden current increases, and also when operating at extreme temperatures as temperature affects the operating characteristics of diodes in general. It cannot however accurately be predicted whether a particular WLED will fail in open or closed circuit and the invention provides a means of mitigating the effect of failure of one WLED on those which remain functioning in the circuit. The control means immediately increases or reduces the total current flow to all the chains depending on whether a WLEDs fails in short or open circuit. The control means also detects operating temperature and user light intensity requirement and adjusts various currents accordingly.
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Citations
18 Claims
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1. A lighting device comprising:
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a cluster of WLEDs, at least some of which WLEDs are chained in parallel between a pair of lines that apply a voltage across the WLED chains;
first current altering means that can be controlled to alter the total current delivered to the individual WLED chains;
second current altering means provided in each WLED chain, the second current altering means being controllable to alter the current flow in that WLED chain;
current measuring means in each WLED chain; and
control means communicating with the current measuring means within in each WLED chain, the control means being capable of controlling at least one of (i) the first current altering means and (ii) at least one of the second current altering means in response to variations in measured current in the individual WLED chains. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 18)
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16. A lighting device comprising:
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a control means for controlling current flow in a plurality of individual parallel connected WLED chains arranged between a pair of voltage lines;
first current altering means situated between one of the voltage lines and the individual parallel connected chains for altering the total current delivered to the individual parallel connected chains, each of said individual parallel connected chains having at least one WLED connected therein; and
second current altering means and current measuring means situated in each WLED chain with the at least one WLED of that chain, the control means being adapted to communicate with the current measuring means in each individual parallel connected chain and capable of controlling at least one of (i) the first current altering means and (ii) at least one of the second current altering means in response to variations in measured current in the individual chains. - View Dependent Claims (17)
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Specification