SIMULTANEOUS ADJUSTING CIRCUIT FOR BRIGHTNESS AND CONTRAST OF LIQUID CRYSTAL DISPLAY MONITOR

• Main Author: YAMAGATA TAKATSUGU
• Format: Patent
• Language: English
• Published: 16.03.1999
• Edition: 6
• Subjects: ADVERTISING; ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICESUSING STATIC MEANS TO PRESENT VARIABLE INFORMATION; CRYPTOGRAPHY; DEVICES OR ARRANGEMENTS, THE OPTICAL OPERATION OF WHICH ISMODIFIED BY CHANGING THE OPTICAL PROPERTIES OF THE MEDIUM OF THEDEVICES OR ARRANGEMENTS FOR THE CONTROL OF THE INTENSITY,COLOUR, PHASE, POLARISATION OR DIRECTION OF LIGHT, e.g.SWITCHING, GATING, MODULATING OR DEMODULATING; DISPLAY; EDUCATION; ELECTRIC COMMUNICATION TECHNIQUE; ELECTRICITY; FREQUENCY-CHANGING; NON-LINEAR OPTICS; OPTICAL ANALOGUE/DIGITAL CONVERTERS; OPTICAL LOGIC ELEMENTS; OPTICS; PHYSICS; PICTORIAL COMMUNICATION, e.g. TELEVISION; SEALS; TECHNIQUES OR PROCEDURES FOR THE OPERATION THEREOF

PROBLEM TO BE SOLVED: To prevent the occurrence of white saturation even when brightness is increased by video black level control. SOLUTION: This simultaneous adjusting circuit is provided with a video amplifier 4, a maximum brightness voltage detecting circuit 6, which detects a maximum brightness voltage value of a video signal, a level comparator 1, which adopts a drive voltage value of white saturation point as a reference voltage and inputs it and an output of the maximum brightness voltage detector 6, a microcomputer 2 which controls a contrast set point from the output of the level comparator 1, a D/A converter, and an A/D converter.