JPS60101871U

JPS60101871U - television receiver

Info

Publication number: JPS60101871U
Application number: JP19414083U
Authority: JP
Inventors: 関上　秀雄
Original assignee: 株式会社東芝
Priority date: 1983-12-19
Filing date: 1983-12-19
Publication date: 1985-07-11

Abstract

(57)【要約】本公報は電子出願前の出願データであるた
め要約のデータは記録されません。(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Brief explanation of drawings]

第１図は従来のテレビジョン受像機におけるチューナ、
■下回路及びＡＦＴ回路部分を示す回路図、第２図は第
１図のＶＩＰ回路における入力電界強度に対するＩＦＡ
ＧＣ電圧の変化を示す特性図、第３図は第１図めＡＦＴ
回路におけるチューナ局部発振周波数のいずれに対する
ＡＦＴ電圧の変化を示す特性図、第４図は本考案に係る
テレビジョン受像機を示す回路図、第５図は第４図のＩ
ＦＡＧＣ電圧検出用トランジスタのベース設定電圧を示
すた、めの入力電界強度対ＩＦＡＧＣ電圧の関係を示す
特性図である。１−ｆニー−）−１２・：・ｖＩＦ回路、４−ＩＦ端子
、１０・・・ＩＦＡＧＣ出力端子、１１・・・ＡＦＴ回
路、１２゜・　１３・・−ＡＦＴ出力端子、１４・・・
チュー−）ＡＦＴ制御端子、１５・・・ＡＦ　Ｔ＃−動
スイッチ、１６・・・ＡＦＴオフ動作側端子、１８・・
−ＡＦＴオン動作側端子、２２′・・・検出及びスイッ
チング回路、２３・・・ＩＦＡＧＣ電圧検出用トランジ
スタ、２４・・・スイッチングトランジスタ、２５・・
・電界効果型トランジスタ。 −ｖＡｔ　　　　　　　第２図　　− １１１− ！＋ →−Ｈ２−申−Ｈ３−− １１− −１− 一、　　　−第４図 ″″雪、’　　　−−＝　、　、／％、１　　　　　　
　　／　　ｉＭ−Figure 1 shows a tuner in a conventional television receiver.
■Circuit diagram showing the lower circuit and AFT circuit part, Figure 2 is the IFA for the input electric field strength in the VIP circuit of Figure 1.
Characteristic diagram showing changes in GC voltage, Figure 3 is the same as Figure 1.AFT
A characteristic diagram showing changes in AFT voltage with respect to each tuner local oscillation frequency in the circuit, FIG. 4 is a circuit diagram showing a television receiver according to the present invention, and FIG.
FIG. 3 is a characteristic diagram showing the relationship between input electric field strength and IFAGC voltage, which shows the base setting voltage of the FAGC voltage detection transistor. 1-f knee-) -12... vIF circuit, 4-IF terminal, 10... IFAGC output terminal, 11... AFT circuit, 12°, 13... -AFT output terminal, 14...
Chu-) AFT control terminal, 15...AF T#-motion switch, 16...AFT off operation side terminal, 18...
-AFT on operation side terminal, 22'... detection and switching circuit, 23... IFAGC voltage detection transistor, 24... switching transistor, 25...
・Field-effect transistor. -vAt Figure 2 - 1 11-! ＋ →-H2-Sen-H3-- 11- -1- 1, -Figure 4 ``''Snow,' --= , , /%, 1
/iM-

Claims

[Scope of utility model registration request]

An automatic gain control circuit and an automatic fine adjustment circuit are disposed between the tuner and the video intermediate frequency amplification circuit, and the output of the video intermediate frequency amplification circuit is kept constant depending on the strength of the input electric field of the antenna, and the output of the video intermediate frequency amplification circuit is In a television receiver configured to control any of the tuner local oscillation frequencies so that the frequency is constant, a detection circuit detects a change in the gain control voltage obtained by the video intermediate frequency amplification circuit. Based on this detection result, the two fine adjustment output voltages having reciprocal characteristics created by the automatic fine adjustment circuit are short-circuited or opened to create an ON operation for controlling the tuner local oscillation frequency. is provided with a switching circuit that is turned on, and is configured to control the switching circuit according to changes in the input electric field strength, and to turn on the switching circuit when there is no signal electric field and turn the automatic fine adjustment circuit into an OFF operation state. A television receiver characterized by: