Non-linear light-emitting load current control
First Claim
1. A sensor circuit for detecting a current supplied to a non-linear load and for producing a current reading dependent on a condition of operation of said non-linear load, said sensor circuit comprising:
- a) first and second serially interconnected resistors also connected in series with the non-linear load; and
b) a variable impedance connected in parallel with one of amid first and second resistors, said impedance varying with said condition of operation of the non-linear load;
whereby at least a portion of the current through the non-linear load flows through the sensor circuit to enable said first and second serially interconnected resistors and said variable impedance to produce a variable voltage signal representative of the current through the non-linear load and dependent on said condition of operation.
3 Assignments
0 Petitions
Accused Products
Abstract
A sensor circuit for detecting a current supplied to a non-linear light-emitting diode (LED) and for producing a current reading dependent on temperature. The sensor circuit comprises first and second serially interconnected resistors also connected in series with the LED, and a temperature-dependent impedance connected in parallel with one of the first and second resistors. At least a portion of the current through the LED flows through the sensor circuit to enable the first and second serially interconnected resistors and said temperature-dependent Impedance to produce a variable voltage signal representative of the current through the LED and dependent on temperature. In another embodiment, the invention discloses a substantially constant intensity light source comprising a controllable dc voltage and current source having first and second terminal, a plurality of non-linear LEDs connected between the first and second terminals and supplied with dc voltage and current from the controllable dc voltage and current source, and a current sensor circuit connected in series with the LEDs between the first and second terminals. The current sensor circuit having a temperature-dependent impedance and being supplied with at least a portion of the current through the LEDs, whereby the impedance produces a variable current-representative signal. The light source also comprises a voltage and current control feedback circuit connected between the current sensor circuit and the controllable dc voltage and current source and through which the dc voltage and current source is controlled In relation to the variable current-representative signal to adjust the dc voltage and current to amplitudes that keep the intensity of the light source substantially constant.
68 Citations
20 Claims
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1. A sensor circuit for detecting a current supplied to a non-linear load and for producing a current reading dependent on a condition of operation of said non-linear load, said sensor circuit comprising:
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a) first and second serially interconnected resistors also connected in series with the non-linear load; and
b) a variable impedance connected in parallel with one of amid first and second resistors, said impedance varying with said condition of operation of the non-linear load;
whereby at least a portion of the current through the non-linear load flows through the sensor circuit to enable said first and second serially interconnected resistors and said variable impedance to produce a variable voltage signal representative of the current through the non-linear load and dependent on said condition of operation. - View Dependent Claims (2, 3)
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4. A substantially constant intensity light source comprising:
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a) a controllable dc voltage and current source having fir&
t and second terminals;
b) a non-linear light-emitting load connected between the first and second terminals and supplied with dc voltage and current from the controllable de voltage and current source;
c) a current sensor circuit connected in series with the non-linear light-emitting load between said first and second terminals, the current sensor circuit having an impedance varying with a condition of operation of the light-emitting load and being supplied with at least a portion of the current through said non-linear light-emitting load, whereby the variable impedance produces a variable current-representative signal; and
d) a voltage and current control feedback circuit connected between said current sensor circuit and said controllable dc voltage and current source and through which the dc voltage and current source is controlled in relation to the variable current-representative signal to adjust the dc voltage and current to amplitudes that keep the light intensity produced by the light source substantially constant. - View Dependent Claims (5, 6, 7, 8, 9, 10)
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- 11. A substantially constant intensity light source as defined in claim 1O, wherein said at least one light-emitfing diode comprises a plurality of sets of light-emitting diodes connected in parallel.
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13. A method for keeping the intensity of a light source substantially constant, comprising:
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a) supplying from a controllable dc voltage and current source a dc voltage and current to a non-linear light-emitting load;
b) supplying at least a portion of the current through said non-linear light-emitting load to a current sensor circuit having an impedance varying with a condition of operation of the light-emitting load, whereby the variable impedance produces a variable current-representative signal; and
c) feedback controlling said dc voltage and current in relation to the variable current-reprerentative signal to adjunt the do voltage and current to amplitudes that keep the light intensity produced by the light source substantially constant.
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20. A substantially constant intensity light source comprising:
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a) a non-linear light-emitting load;
b) a controllable dc voltage and current source for supplying the non-linear light-emitting load with dc voltage and current;
c) a current sensor circuit connected in series with the non-linear light-emitting load and the controllable dc voltage and current source, the current sensor circuit having an impedance varying with a condition of operation of the light-emitting load and being supplied with at least a portion of the current through said non-linear light-emitting load, whereby the variable impedance produces a variable current-representative signal; and
d) a voltage and current control feedback circuit connected between said current sensor circuit and said controllable dc voltage and current source for controlling the dc voltage and current source in relation to the variable current-representative signal to thereby adjust the dc voltage and current to amplitudes that keep the light intensity produced by the light source substantially constant.
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Specification