Backlight adjustment circuit and electronic device

摘要

An backlight adjustment circuit (20), configured to adjust luminance of light emitted by one light-emitting diode (LED) string (11) of a LED module (10), the LED string (11) includes a plurality of LEDs (D) and a current control resistor (R). The backlight adjustment circuit (20) includes a light sensing circuit (21) for sensing the luminance of one corresponding LED string (11) and producing a corresponding light sensing signal value; a comparison unit (22) for comparing the light sensing signal value with a preset reference value, and producing a first signal when comparing the light sensing signal value is less than the preset reference value, else producing a second signal; and an adjustment unit (23) for decreasing the luminance of the LED string (11) when receiving the first signal and increasing the luminance of the LED string (11) when receiving the second signal.

主权项

1. An electronic device, comprising a light-emitting diode (LED) module and at least one backlight adjustment circuit, each backlight adjustment circuit is configured to detect the luminance of the light emitted by a corresponding one LED string and adjust the luminance correspondingly, each LED string comprises a plurality of LEDs and a current control resistor connected between a positive voltage port and ground in series; wherein, the backlight adjustment circuit comprises:
a light sensing circuit, configured to sense the luminance of light emitted by one corresponding LED string and produces a corresponding light sensing signal value; a comparison unit, configured to compare the light sensing signal value produced by the light sensing circuit with a preset reference value, and produce a first signal when comparing the light sensing signal value is less than the preset reference value, and produce a second signal when comparing the light sensing signal value is greater than the preset reference value; and an adjustment unit, configured to control to decrease a current flowing through the LED string to decrease the luminance of the light emitted by the LED string, when receiving the first signal produced by the comparison unit; and to control to increase the current flowing through the LED string to increase the luminance of the light emitted by the LED string, when receiving the second signal produced by the comparison unit; wherein the light sensing circuit comprises a photoelectric converter and a voltage difference calculating unit, the photoelectric converter is located on an area where the LED string is, and is configured to sense the luminance of the light emitted by the LED string and produce corresponding first voltage and second voltage; the voltage difference calculating unit is configured to calculate a voltage difference of the first voltage and the second voltage according to the first voltage and the second voltage; the preset reference value is a reference voltage, the comparison unit compares the voltage difference of the first voltage and the second voltage with the reference voltage, and produces the first signal when comparing the voltage difference is less than the reference voltage, and produces the second signal when comparing the voltage difference is greater than the reference voltage.