Patent ID: 6445143
Filing Date: 2002-09-03
Classification: G09G,H05B

Abstract:
An inverter for LCD backlight, comprising:a first switching element connected to an input terminal of a DC/AC converter operating a lamp by using an inputted power for determining supply of the inputted power; a dimming control section for comparing a first dimming signal with a second dimming signal inputted from outside in accordance with a dimming mode selection signal, and outputting first to third control signals to perform a PWM dimming, an analog dimming or a complex dimming control; an error amplifier for receiving a feedback signal F/B of a feedback part connected to the lamp by means of an inverting terminal, and a first control signal outputted from the dimming control section by means of a non-inverting terminal to output a compared signal in accordance with a state of the signals inputted to each terminal; a first comparator for receiving a pyramidal wave for controlling the PWM dimming having a predetermined cycle or a third control signal outputted from the dimming control section by means of the non-inverting terminal, and a second control signal outputted from the dimming control section by means of the inverting terminal, comparing the two signals, and outputting a signal in accordance with a compared value; a second switching element connected between an output terminal of the error amplifier and a ground terminal for performing on/off operation in accordance with a voltage level of a signal outputted from the first comparator, and converting a potential of the output terminal of the error amplifier to a ground potential; and a second comparator for receiving the output signal of the error amplifier by means of the non-inverting terminal and an oscillating signal of a predetermined cycle by means of the inverting terminal, and comparing the two signals to control on/off operations of the first switching element in accordance with the compared result.