| 摘要 |
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.
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