JPH0228184U

JPH0228184U -

Info

Publication number: JPH0228184U
Application number: JP10661288U
Authority: JP
Priority date: 1988-08-12
Filing date: 1988-08-12
Publication date: 1990-02-23

Description

[Brief explanation of drawings]

図面は本考案の一実施例を示すもので、第１図
は液晶表示式テレビジヨン受像機の全体の回路構
成を示すブロツク図、第２図は第１図におけるキ
ードＡＧＣ回路の詳細を示すブロツク図、第３図
ａ，ｂは一般的なビデオ信号用Ａ／Ｄ変換回路の
動作点例を示す図、第４図ａ，ｂは第１図におけ
るビデオ信号用Ａ／Ｄ変換回路の動作点例を示す
図、第５図はＹ検波回路の原理的構成を示す図、
第６図はコントラスト・コントロール回路のゲイ
ン特性を示す図、第７図ａ，ｂはＹ検波回路への
入力信号波形例を示す図である。２……チユーナ、４……映像／音声検波回路、
５……ビデオスイツチ回路、１１……Ｙ検波回路
、１２，１５……コントラスト・コントロール回
路、１３……Ｙ信号処理回路、１６……復調回路
、１７〜１９……Ａ／Ｄ変換回路、２０……表示
コントロール回路、２１……液晶表示パネル、３
０……キードＡＧＣ回路、３１……ゲイン・コン
トロールアンプ、３２……バツフアアンプ、３３
……ＬＰＦ、３４……シンク・チツプ・クランプ
回路、３５……キーパルス付加回路、３６……キ
ーパルス発生回路、３７……ピークホールド回路
。 The drawings show one embodiment of the present invention; FIG. 1 is a block diagram showing the overall circuit configuration of a liquid crystal display television receiver, and FIG. 2 is a block diagram showing details of the keyed AGC circuit in FIG. 1. Figures 3a and 3b are diagrams showing examples of operating points of a general A/D conversion circuit for video signals, and Figures 4a and b are operating points of the A/D conversion circuit for video signals in Figure 1. A diagram showing an example, FIG. 5 is a diagram showing the principle configuration of a Y detection circuit,
FIG. 6 is a diagram showing the gain characteristics of the contrast control circuit, and FIGS. 7a and 7b are diagrams showing examples of input signal waveforms to the Y detection circuit. 2...Tuner, 4...Video/audio detection circuit,
5... Video switch circuit, 11... Y detection circuit, 12, 15... Contrast control circuit, 13... Y signal processing circuit, 16... Demodulation circuit, 17-19... A/D conversion circuit, 20 ... Display control circuit, 21 ... Liquid crystal display panel, 3
0... Keyed AGC circuit, 31... Gain control amplifier, 32... Buffer amplifier, 33
...LPF, 34...Sink chip clamp circuit, 35...Key pulse addition circuit, 36...Key pulse generation circuit, 37...Peak hold circuit.

Claims

[Claims for Utility Model Registration] (1) An input means for switching and inputting multiple systems of video signals, and an AGC circuit for adjusting the level of the video signal inputted by the input means to a constant level;
A liquid crystal display type image comprising a contrast control means for controlling the contrast of the video signal adjusted to a constant level from the AGC circuit, and a display means for displaying the video signal from the contrast control means on a liquid crystal display. Display device. (2) The liquid crystal display type image display device according to claim (1), wherein the input means switches between a received video signal and an externally input video signal.