Patent ID: 7893624
Filing Date: 2011-02-22
Classification: H05B

Abstract:
1. A backlight control circuit comprising: an inverter configured to provide an alternating current voltage to a lamp; a pulse width modulation (PWM) circuit configured to provide a pulse control signal to the inverter; and a frequency setting circuit configured to regulate a frequency of the pulse control signal provided by the PWM circuit according to an environment temperature; wherein the frequency setting circuit comprises an adjustable resistor, a temperature sensor configured to sense the environment temperature, a look-up table and an encoder, the look-up table comprises a plurality of environment temperature values and a plurality of binary instructions corresponding to the environment temperature values, the frequency setting circuit searches the look-up table for a binary instruction corresponding to the environment temperature and output the binary instruction to the encoder, the encoder encodes the binary instruction, and the frequency setting circuit is further configured to regulate a resistance of the adjustable resistor according to the encoded binary instruction.