JPS6311739U

JPS6311739U -

Info

Publication number: JPS6311739U
Application number: JP10409886U
Authority: JP
Priority date: 1986-07-07
Filing date: 1986-07-07
Publication date: 1988-01-26
Anticipated expiration: 2001-07-07
Also published as: JPH0538422Y2

Description

[Brief explanation of drawings]

第１図は本考案の一実施例のブロツク図、第２
図は第１図の実施例の動作説明に供する信号波形
図、第３図は従来例のブロツク図、第４図は第３
図の動作説明に供する信号波形図、第５図は記録
信号の周波数分布を示す図、第６図は磁化パター
ンの説明図、第７図はパイロツト信号の周波数分
布を示す図、第８図は回転磁気ヘツドのトレース
の状態を示す図である。７……ＡＧＣ回路、８……ビート信号形成回路
、１３，２０……第１、第２切換回路、１４，１
５……第１、第２整流回路、１７，１８……第１
、第２サンプルホールド回路、２１……制御信号
形成回路。 Fig. 1 is a block diagram of an embodiment of the present invention;
The figure is a signal waveform diagram for explaining the operation of the embodiment shown in Fig. 1, Fig. 3 is a block diagram of the conventional example, and Fig. 4 is a diagram of the third embodiment.
Fig. 5 is a diagram showing the frequency distribution of the recording signal, Fig. 6 is an explanatory diagram of the magnetization pattern, Fig. 7 is a diagram showing the frequency distribution of the pilot signal, and Fig. 8 is a diagram showing the frequency distribution of the pilot signal. FIG. 3 is a diagram showing the state of tracing of a rotating magnetic head. 7... AGC circuit, 8... Beat signal forming circuit, 13, 20... First, second switching circuit, 14, 1
5...first, second rectifier circuit, 17,18...first
, second sample and hold circuit, 21... control signal forming circuit.

Claims

[Claims for Utility Model Registration] Four types of pilot signals with different frequencies are sequentially switched for each field, combined with an FM luminance signal, etc., and recorded on a magnetic tape, and tracking control is performed using the pilot signals during playback. In an azimuth recording type helical scan video tape recorder, AGC (automatic gain control) is used to adjust the output levels of four types of reference pilot signals having the same frequencies as each of the four types of pilot signals, based on a control signal. ) circuit; a beat signal forming circuit that forms two types of beat signals based on the pilot signal reproduced from the magnetic tape and the four types of reference pilot signals from the AGC circuit; a first switching circuit that outputs two types of error signals by switching the polarity of both beat signals from the beat signal forming circuit for each field; and a first switching circuit that rectifies the two types of error signals from the first switching circuit. 1. A second rectifier circuit, a comparator that compares the output levels of both rectifier circuits, and based on each error signal from each of the rectifier circuits,
a control signal forming circuit that forms a control signal for the AGC circuit; the control signal forming circuit includes first and second circuits that sample and hold each error signal from each of the rectifier circuits in response to a head switching pulse; 2 sample and hold circuits, and the outputs of both sample and hold circuits are switched alternately for each field in response to a head switching pulse, and the control signal A is used as a control signal.
A video tape recorder comprising a second switching circuit that outputs to a GC circuit.