# US 7,746,318 B2 · Liquid crystal display backlight inverter

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 7,746,318 B2
- Document ID: US7746318B2
- Status: Granted
- Kind: B2
- Application number: 11/695,222
- Filed: 2007-04-02
- Published: 2007-10-04
- Granted: 2010-06-29
- Earliest claimed: 2006-04-04
- Assignees: Samsung Electro-Mechanics Co., Ltd.
- Inventors: Sang Cheol Shin; Byoung Own Min; Chang Woo Ha; Jung Chul Gong
- Web page: https://patentgrep.com/patent/US7746318B2

## CPC

- H05B 41/386: {for speeding-up the lighting-up}
- H05B: ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL

## Abstract

An LCD backlight inverter includes a soft starter for generating a soft-start reference voltage gradually increasing as the driving power begins to be supplied. The LCD backlight inverter also includes a first error detector for receiving a first feedback voltage indicating the magnitude of driving current of the lamp and for comparing a smaller value out of a predetermined first reference voltage and the soft-start reference voltage with the first feedback voltage to generate a first error signal corresponding to the difference between the smaller value and the soft-start reference voltage. The LCD backlight inverter further includes a pulse width modulation comparator for comparing the first error signal and a triangle wave oscillation signal to output the pulse width modulation control signal with a predetermined duty ratio. The LCD backlight inverter prevents application of over-current and over-voltage to the LCD backlight to prolong the lifetime of the backlight.

## Claims

### Claim 1

A liquid crystal display backlight inverter, which generates a pulse width modulation control signal to regulate the magnitude of driving power of a liquid crystal display backlight lamp, comprising:
a soft starter for generating a soft-start reference voltage gradually increasing as the driving power begins to be supplied;
a first error detector for receiving a first feedback voltage indicating the magnitude of driving current of the lamp and for comparing a smaller value out of a predetermined first reference voltage and the soft-start reference voltage with the first feedback voltage to generate a first error signal corresponding to the difference between the smaller value and the soft-start reference voltage; and
a pulse width modulation comparator for comparing the first error signal and a triangle wave oscillation signal to output the pulse width modulation control signal with a predetermined duty ratio.

### Claim 2 (depends on 1)

The liquid crystal display backlight inverter according to claim 1, wherein the soft starter comprises:
a switch connected to one end of a power source, the switch being turned on as the driving power is supplied to the lamp; and
a capacitor connected between the other end of the switch and a ground,
wherein the soft-starter provides the voltage generated at a connection point of the switch and the capacitor as the soft-start reference voltage.

### Claim 3 (depends on 1)

The liquid crystal display backlight inverter according to claim 1, further comprising:
a second error detector for receiving a second feedback voltage indicating the magnitude of driving voltage of the lamp and for comparing a smaller value out of a predetermined second reference voltage and the soft-start reference voltage with the second feedback voltage to generate a second error signal corresponding to the difference between the smaller value and the soft-start reference voltage,
wherein the pulse width modulation comparator compares a smaller value of the first error signal and the second error signal with the triangle wave oscillation signal to determine the duty ratio of the pulse width modulation control signal.