JPS59167191A - Rotary head type magnetic video recording and reproducing device - Google Patents

Abstract

PURPOSE:To obtain a burst gate signal having a delay time in response to the reproducing mode from a horizontal synchronizing signal by inputting the horizontal synchronizing signal to plural integration circuits having different time constant from each other and extracting selectively its output in response to the switching of the reproducing modes. CONSTITUTION:The horizontal synchronizing signal applied to the 1st integration circuit 2 is integrated by a time constant decided a capacitor and a coil, and the horizontal synchronizing signal applied to the 2nd integration circuit 4 is integrated by a time constant decided by a capacitor, a coil and a resistor, and the integration waveform is widened. The horizontal synchronizing signal outputted from the 1st and 2nd integration circuits 2, 4 is applied to a switching circuit 5, an output of the 1st integration circuit 2 is changed over at the normal reproduction and the output of the 2nd integration circuit 4 is changed over at the special reproduction selectively and they are applied to a burst gate circuit 3 as a burst gate signal. No burst signal missing takes place at the special reproduction even if a width of the horizontal synchronizing signal is narrowered by providing the integration circuit for the special reproduction, allowing to reproduce the burst signal with such condition.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a rotating head type magnetic recording and reproducing apparatus (VTR). The purpose is to extract color burst signals more accurately.

Conventional Structure and Problems The burnout gate means of a conventional VTR will be explained with reference to FIG.

In Figure 1, 1 is a horizontal sync signal separation circuit for increasing the horizontal sync signal in the reproduced video, 2 is composed of a coil and a capacitor, and the horizontal sync signal is separated by a time constant determined by the coil and capacitor. This is an integration circuit for delay. 3 is a burst gate circuit which increases only a burst signal from the reproduced video signal by using the horizontal synchronizing signal delayed by the integrating circuit 2 as a gate signal.

In the above configuration, when a video signal is input now, the horizontal synchronization signal separation circuit 1 extracts only the horizontal synchronization signal. This extracted horizontal synchronization signal is supplied to an integrating circuit 2 composed of a coil and a capacitor, and is delayed so that the output horizontal synchronization signal is at the burst signal position.

Then, the horizontal synchronizing signal that has passed through the integrating circuit 2 is added to the burst gate circuit 3, and only the signal (burst signal) at the position of the horizontal synchronizing signal that has passed through the integrating circuit 2 of the video signal input from the video input terminal is input. I'm taking it out.

However, the time constant determined by the capacitor and coil that make up the integration circuit 2 is for the normal playback mode, where the tape speed during playback is equal to the tape speed during recording, so it cannot be used in the special playback mode. Since the relative speed between the magneto-electric head and the tape is different from that in the normal playback mode, there is a problem in that the time constant of the capacitor and coil cannot increase the correct burst signal.

OBJECTS OF THE INVENTION The present invention eliminates these drawbacks and provides a VTR 1 that can faithfully increase burst signals even in special playback mode.

Structure of the Invention The present invention provides horizontal synchronization by inputting a horizontal synchronization signal to a plurality of integrating circuits having different time constants, and selectively extracting the outputs of the plurality of integrating circuits according to switching of the playback mode. The objective is to obtain a burst gate signal having a delay time depending on the reproduction mode from the signal.

DESCRIPTION OF EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. 2 and 3.

FIG. 2 is a block diagram of a burst gate means of a VTR which is an embodiment of the present invention, and FIG. 3 is a waveform diagram of input/output signals of each part.

In Figure 2, 1 is a horizontal signal separation circuit that extracts only the horizontal synchronizing signal from the input video signal, and 2 is the first integrating circuit for normal reproduction, which is composed of a capacitor and a coil. There is. 3 is a burst gate circuit which extracts only a burst signal from an input video signal using a burst gate signal. A second integrating circuit 4 for special reproduction has a time constant different from that of the first integrating circuit 2, and is composed of a resistor, a coil, and a capacitor. Reference numeral 5 denotes a switching circuit that switches between the output of the first integrating circuit 2 for normal reproduction and the output of the second integrating circuit 4 for special reproduction in accordance with switching of the reproduction mode.

Next, the operation of this device will be explained.

A horizontal synchronizing signal (FIG. 3A) is extracted from the video signal input to the horizontal synchronizing signal separation circuit 1, and the horizontal synchronizing signal is supplied to the first integrating circuit 2 and the second integrating circuit 4.

The horizontal synchronizing signal supplied to the first integrating circuit 2 can be integrated with a time constant determined by a capacitor and a coil, and the horizontal synchronizing signal supplied to the second integrating circuit 4 can be integrated by a time constant determined by a capacitor, coil, and resistor. The second integrating circuit 4 has a wider integrated waveform than the first integrating circuit 2.

The horizontal synchronizing signals output from the first integrating circuit 2 and the second integrating circuit 4 (Fig.
For special reproduction of the output of the second integrating circuit 2, the output of the second integrating circuit 4 is selectively switched and supplied to the burst gate circuit 3 as a burst gate signal.

In this manner, by providing an integrating circuit for special reproduction, even if the width of the horizontal synchronizing signal becomes narrow in the special reproduction state, it is possible to reproduce the burst signal without missing the burst signal.

In this embodiment, an example of a device including a capacitor, a coil, and a resistor is shown, but any other devices that operate in the same manner as these may be used.

As described above, according to the present invention, even in the special playback state,
It is possible to provide a magnetic recording and reproducing device that can reliably extract burst signals and perform high-quality reproduction in the same way as in the normal reproduction state.

[Brief explanation of drawings]

Figure 1 is a block diagram of a conventional burst gate means, Figure 2 is a block diagram of a conventional burst gate means;
The figure is a block diagram of the main parts of a magnetic recording/reproducing apparatus which is an embodiment of the present invention, and FIG. 3 is a waveform diagram of input/output signals of each part of the apparatus. 1...Horizontal synchronization signal separation circuit, 2...
Integral circuit, 3... Burst gate circuit, 4...
...Integrator circuit, 6...Switching circuit.

Claims (1)

[Claims] Separating a horizontal synchronizing signal from a reproduced video signal, inputting the horizontal synchronizing signal to a plurality of integrating circuits each having a different time constant, and selecting one of the outputs of the plurality of integrating circuits according to switching of the reproduction mode. A rotary head type magnetic recording and reproducing apparatus characterized in that the extracted output is used as a burst gate signal for extracting a burst signal from the reproduced video signal.