JPS61239404A - Rotary head type magnetic video recording and reproducing device - Google Patents

Abstract

PURPOSE:To attain the consecutive recording with no noise on the screen of a TV receiver when the corresponding section is reproduced, by using a circuit which secures the synchronization of the timing of the recording part indicating signal of a VTR with the head switching signal. CONSTITUTION:A recording mode setting signal (c) of the Q output is set at a high level at the starting rise edge of a head switching signal (b) after a start indicating signal (a) is changed to a high level from a low level. Thus the video recording starts. This recording ends when the signal (c) is set at a low level at the starting rise of the signal (b) after the signal (a) is changed to a high level from a low level. In such a way, the starting point of a recording mode is always set at a place near the vertical synchronizing signal of the 1st video signal recorded previously. Thus the noises if produced at a switching point are not given on a reproduced screen.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention sequentially switches and uses a plurality of rotary heads rotated in synchronization with a vertical synchronization signal of a video signal to be recorded.
A helical scan rotary head type that records the video signal as a plurality of recording trajectories that are inclined with respect to the longitudinal direction of the magnetic tape and parallel to each other, and so that the vertical synchronization signal is located at a fixed position on each recording trajectories. Magnetic Takuga playback device (
(hereinafter referred to as VTR).

BACKGROUND ART Conventionally, in a helical scan type VTR, in the case of so-called splicing, in which a second video signal is recorded consecutively to the first video signal on a magnetic tape on which a first video signal has been recorded, playback is performed. Sometimes, when switching from a first video signal to a second video signal, the first video signal is phase-synchronized with the vertical synchronization signal of the second video signal so as not to cause fluctuations in the tracking control system. It is configured to play back for a predetermined period of time (for example, one second) and then switch to the recording mode. In other words, from the stop state, after loading is finished, the mode enters the recording mode after running in the playback mode for a certain period of time, and when recording is paused, it is rewound in the opposite direction for a certain period of time at the same time as the pause, and after the pause is released, this rewinding is resumed. After running in playback mode for a predetermined period slightly shorter than the period of time, switching to record mode occurs. By doing this, the phases of the vertical synchronization signals of the first and second video signals match, the first video signal and the second video are recorded in a well-connected manner, and even when recording is paused, continuous recording is possible without any gap. Can be recorded.

Problems to be Solved by the Invention However, in the configuration described above, the recording start timing is simply a predetermined period of time after loading is finished or after a pause is released, so the vertical synchronization of the video signal is difficult. In some cases, the recording mode is switched to at a point other than the section corresponding to 10 horizontal synchronization signals before and after the signal, and in such a case, when that section is played back, noise may appear on the playback screen of the TV receiver at the part where recording starts. The problem was that

In view of the above-mentioned problems, the present invention provides a rotary head type magnetic recording and playback system that does not generate noise when reproducing that section by always setting the recording start timing within 10 horizontal synchronization signals before and after the vertical synchronization signal. It provides armor.

Means for Solving the Problems In order to solve the above problems, the rotary head type magnetic recording/reproducing apparatus of the present invention is provided with a structure in which the timing of recording start is synchronized with the head switching signal in the reproduction state. . .

According to the above-described configuration, the head switching signal is generated in synchronization with the rotational phase of the rotary head, as is well known.
A predetermined period of the vertical synchronization signal (for example, horizontal synchronization signal 7 of the reproduced video signal during playback and of the recording signal during recording)
Since the rotational phase of the rotary head is controlled so that the switching occurs before the head switching signal (rise and fall), the switching points (rising and falling edges) of the head switching signal are always the same as the vertical synchronization signal of the video signal to be recorded or the reproduced video signal. located before a predetermined period of time. Therefore, if the recording mode is switched at the switching point of this head switching signal, the noise caused by switching the screen at the start of recording will not appear on the screen of the television receiver.

' Embodiment Hereinafter, a VTR according to an embodiment of the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram of the main parts of a VTR used in continuous shooting in a first embodiment of the present invention. In Fig. 1, 1 is a D-type flip-flop, and when the input applied to the D terminal changes to high or low, the Q output changes to high or low at the rising edge of the next clock input to the clock terminal CP. change. A start instruction signal a that instructs to start continuous shooting is applied to the D input terminal of this D type flip-flop.
A head switching signal for switching heads during reproduction is applied to the CP terminal.

The operation of the VTR configured as described above will be explained below with reference to FIG.

FIG. 2 shows a timing diagram of each signal. After the start instruction signal a goes from Low to High, the recording mode setting signal C of the Q output goes High at the first rising edge of the head switching signal. , video recording starts. After the start instruction signal changes from Low to High, the recording mode setting signal C of the Q output changes to Low at the first rising edge of the head switching signal, and recording ends.

As described above, according to this embodiment, since the start point of the recording mode is always placed near the vertical synchronization signal (within 10 horizontal synchronization signals) of the first video signal recorded in advance, noise may occur at the switching point. Even if this occurs, it is not substantially displayed on the playback screen.

FIG. 3 is a block diagram of the main parts of a VTR used for continuous shooting, showing a second embodiment of the present invention. The difference from the configuration shown in FIG. 1 is that the head switching signal is input to the CP terminal via a doubler circuit 32.

The operation of the VTR configured as described above will be explained below with reference to FIG.

The waveform obtained by multiplying the head switching signal S by 2 is d, and P is D.
It is input to the clock terminal CP of the type flip-flop 31. Start instruction signal a changes from Low to High,
Or, Q at the first rising edge of the double signal d of the head switching signal after changing from High to Low.
Output recording mode setting signal C is High or Low
Changes to

As described above, by providing the doubling circuit to double the head switching signal, recording is started at the rising or falling edge of the head switching signal, and the start instruction signal a in the first embodiment and the recording The maximum difference with the mode setting signal C can be suppressed to just a few.

Effects of the Invention As described above, the present invention provides a circuit that synchronizes the timing of the recording start instruction signal of the VTR with the head switching signal, thereby eliminating noise on the screen of the television receiver when that section is played back. You can record continuous shots that are not

[Brief explanation of the drawing]

FIG. 1 shows the first part of the rotary head type magnetic recording and reproducing apparatus of the present invention.
Fig. 2 is a waveform diagram for explaining the operation of the same device, Fig. 3 is a block diagram of the main part of another embodiment, and Fig. 4 is a waveform diagram for explaining the operation of the same device. It is. 1...D type flip-flop, 31...
...D type flip-flop, 32...2
Multiplier circuit.

Claims (1)

[Claims] A plurality of rotary heads rotated in synchronization with the vertical synchronization signal of the video signal to be recorded are sequentially switched and used to create a plurality of recording trajectories that are inclined to the longitudinal direction of the magnetic tape and parallel to each other, and which are vertically synchronized. When the video signal is recorded at a fixed position on each recording locus and the second video signal is continuously recorded on the magnetic tape on which the first video signal has been recorded in advance, the first video signal is The reproduction signal is reproduced in phase synchronization with the vertical synchronization signal of the second video signal, and the recording mode is set in synchronization with the switching signal of the rotary head synchronized with the vertical synchronization signal of the second video signal. A rotary head type magnetic recording and reproducing device characterized in that it is configured to switch.