JPH02185184A - Video signal recording and reproducing device - Google Patents

Abstract

PURPOSE:To prevent vertical fluctuation on the screen from being caused by providing a synchronizing signal separator circuit, a synchronizing signal processing circuit, a pseudo V SYNC generating circuit and a pseudo V SYNC insertion circuit and switching a pseudo vertical synchronizing signal into a vertical synchronizing signal of a video signal at the movement of a magnetic head. CONSTITUTION:A synchronizing signal processing circuit 12 inputs a synchronizing delay signal (c) retarded by accurately 1V period from an inputted vertical synchronizing signal (b) to a pseudo V SYNC generating circuit 9. Then the circuit 9 generates a pseudo V SYNC signal (d) whose front ridge comes across at a period of the inputted synchronizing delay signal (c) and outputs it to a pseudo V SYNC insertion circuit 8. The circuit 8 receives an output (a) of a video signal processing circuit 7 and the pseudo V SYNC signal (d) from the circuit 9. Then the circuit 8 inserts the pseudo V SYNC signal (d) according to an insertion command l of a system control circuit 6 in place of a vertical synchronizing signal being an output (e) of a video signal processing circuit and outputs the result to a video signal output terminal 10 as a video output (f). Thus, the pattern is not fluctuated and the vertical fluctuation of the screen due to + or -2H being an allowable limit is not caused.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a video signal recording and reproducing apparatus using a video floppy disk.

2. Description of the Related Art In recent years, image quality has been emphasized in recording and reproducing devices for video floppy disks (hereinafter abbreviated as VF), and in particular, image quality during track feeding has also received attention.

An example of the above-mentioned conventional video signal recording and reproducing apparatus will be described below with reference to the drawings. FIG. 3 is a block diagram of a conventional video signal recording and reproducing apparatus, and FIG. 4 is a waveform diagram of each part. In FIGS. 3 and 4, a magnetic sheet 1 has a plurality of concentric tracks and is rotated by a spindle motor 3. As shown in FIG.

A magnetic head 2 contacts the magnetic sheet 1 and records and reproduces video signals on each track thereof. 4 is a stepping motor that moves the magnetic head onto the track on the magnetic sheet.
It moves in sync with the rotation of the magnetic sheet so as to track it. 6 is a PG signal, which is input to the system control circuit 6 to control the rotational phase of the magnetic sheet 1, and this signal g
Based on this, the system control circuit 6 rotates the spindle motor 3 at a constant speed.

21 is a delay circuit, and a PG multiplied signal obtained by waveform-shaping the output g of the PG sensor 6 in the system control circuit 6 is input to the delay circuit 21. The delay circuit 21 sends the PG multiplied signal to the PG sensor 6.
is delayed by a time corresponding to the rotational phase of the magnetic head 1, and is output to the pseudo V sync generation circuit 9. Based on the delay circuit output 1 (falling edge in the conventional example in Fig. 4),
The pseudo V sink generation circuit generates a pseudo V sink d.

A video signal processing circuit 7 amplifies the video signal on the magnetic sheet 1 detected by the magnetic head 2. Reference numeral 8 denotes a pseudo V-sink insertion circuit, which inputs its output a from the video signal processing circuit 7 and pseudo V-sink d from the pseudo V-sink generation circuit 9, and outputs the video signal processing circuit according to the insertion command 4 of the system control circuit 6. Insert a pseudo V sync d instead of the vertical synchronization signal of e.

It is output to the video signal output terminal 10 as a video output.

The operation of the video signal recording and reproducing apparatus configured as described above will be described below.

A magnetic head 2 fixed on a magnetic track by a stepping motor 4 comes into contact with a magnetic sheet rotated at a constant speed by a spindle motor 3, detects a video signal from the magnetic sheet 1, and sends it to a video signal processing circuit 7. Output.

The output a amplified by the video signal processing circuit 7 is input to the pseudo V-sink insertion circuit 8, but under normal conditions, the output a is input from the system control circuit 6 to the pseudo V-sink insertion circuit 8, and is then sent to the pseudo V-sink d and the video signal processing circuit. Since the insertion command e to replace the vertical synchronization signal of the output a is not issued, the video signal processing circuit output a is output as is as the video output f. During track feeding, the system control circuit 6 causes the magnetic head 2 to vertically move the video signal recorded on the magnetic sheet 1 in synchronization with the output g of the PG sensor 6 so that the track feeding is completed within the vertical erasing period. When the synchronization signal is reached, the stepping motor 4 is driven to send the track. At this time, the magnetic head 2 does not detect the vertical synchronization signal of the video signal because it passes through the guide band between tracks, and its output contains noise, so the video signal processing circuit output a is , there is a lot of noise and the vertical synchronization signal is not clear (mu). However, when moving a track, the system control circuit sends a command e to the pseudo V sync insertion circuit to insert a pseudo V sync d obtained by delaying the PG multiplication signal instead of the vertical synchronization signal of the video signal processing circuit output a. is output (B). As a result, in the video output f output from the pseudo V-sync insertion circuit, the vertical synchronization signal is replaced by the pseudo V-sync signal (C), so vertical synchronization does not flow during track forwarding.

Problems to be Solved by the Invention However, in the above configuration, according to the vF standard, P
Time difference with the leading edge of the G-multiple signal vertical synchronization signal (TH±2H)
allows a tolerance of ±2H, so the image immediately after track feeding is vertically synchronized with pseudo V-sync, so it deviates from the original vertical synchronization by a maximum of ±2H. This±
The 2H misalignment appears as the screen shaking up and down,
In the case of still images such as video floppies, this vertical play is very noticeable and cannot be ignored.

In view of the above-mentioned problems, the present invention provides a video signal recording and reproducing apparatus that makes use of the original vertical synchronizing signal without using the PO multiplication signal, and in which vertical fluctuation of the screen does not occur even during track forwarding.

Means for Solving the Problems In order to solve the above problems, the video signal recording and reproducing device of the present invention includes a sync signal separation circuit that separates a vertical sync signal from a video signal reproduced from a magnetic track, and a sync signal separation circuit that separates a vertical sync signal from a video signal reproduced from a magnetic track. A synchronization signal processing circuit outputs a synchronization delay signal delayed by a predetermined time from the signal, a pseudo V-sync generation circuit outputs a pseudo vertical synchronization signal delayed by a predetermined time from the synchronization delay signal, and a pseudo vertical synchronization signal is used for vertical synchronization of the video signal. This device includes a pseudo V-sync insertion circuit that switches between the pseudo vertical synchronization signal and the video signal, and switches the pseudo vertical synchronization signal with the vertical synchronization signal of the video signal when the magnetic head moves.

Effect The present invention has the above-mentioned configuration, so that P in the VF standard is
(Tolerable time difference between the r signal and the leading edge of the vertical synchronization signal (±2H)
), the actual vertical synchronization signal is divided into one vertical synchronization period (
Vertical synchronization is performed using a pseudo sync delayed by IV), so the screen will not shake up or down.

Embodiment Hereinafter, a video signal recording and reproducing apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a configuration diagram of a video signal recording and reproducing apparatus according to an embodiment of the present invention, and FIG. 2 shows waveform diagrams of various parts. In FIG. 1, reference numeral 11 denotes a synchronization signal separation circuit, into which the video signal a is input from the video signal processing circuit 7.

A vertical synchronization signal is separated from the video signal a and outputted to the synchronization signal processing circuit 12. The synchronization signal processing circuit 12 inputs to the pseudo V sync generation circuit 9 a synchronization delay signal C that is delayed by exactly 1v from the input vertical synchronization signal. The pseudo-V sync generation circuit 9 responds to the input synchronized delay signal C (in the embodiment, to the falling of the synchronized delay signal C).
A pseudo V sink d where the leading edge comes is created and output to the pseudo V sink insertion circuit 8. Similar to the conventional example, the pseudo V sink insertion circuit 8 receives the output a from the video signal processing circuit 7 and the pseudo V sink.
A pseudo Vz sink d is input from the sync generation circuit 9, and according to the insertion command l of the system control circuit 6, a pseudo V sink d is inserted in place of the vertical synchronization signal of the video signal processing circuit output e, and as the video output f. It is output to the video signal output terminal 10. The other configurations are the same as the conventional example.

The operation of the video signal recording and reproducing apparatus configured as described above will be described below with reference to FIGS. 1 and 2.

First, a magnetic head fixed on a magnetic track by a stepping motor 4 contacts a magnetic sheet that is rotated at a constant speed by a spindle motor 3, detects a video signal from the magnetic sheet, and outputs it to a video signal processing circuit 7. . The output a amplified by the video signal processing circuit 7 is input to the pseudo V sink insertion circuit 8, but normally it is input to the system control circuit 6.
Since the insertion command l for exchanging the pseudo V-sync d and the vertical synchronization signal of the video signal processing circuit output a is not issued to the pseudo V-sync insertion circuit 8, the video signal processing circuit output a is output as is as the video output f. Ru.

During track feeding, when the magnetic head 2 detects the vertical synchronization signal of the video signal, as in the conventional example.

Since the stepping motor 4 is moved, the vertical synchronizing signal portion of the video signal a has a lot of noise (see Fig. 2).

Therefore, the vertical synchronization signal outputted from the synchronization signal separation circuit 11 also has an abnormal waveform. However, since the output of the synchronization signal processing circuit 12 at that time is delayed by one vertical synchronization period from the vertical synchronization signal immediately before the track feed, it becomes a normal synchronization delay signal C, which is a pseudo V synchronization signal d. is also normal. At this time, since the track is being fed, an insertion command l is output from the system control circuit 6 to the pseudo V-sync insertion circuit 8, and a pseudo V-sync is added to the noisy vertical synchronization signal portion of the video signal a. d is inserted,
The video output is normal. In addition, the vertical synchronization signal sumo, which has an abnormal waveform due to track forwarding, is delayed by the synchronization signal processing circuit 12 and the pseudo V sync generation circuit 9 and is output as a pseudo V sync d, but the output is normal. It is not. However, since the system control circuit e does not cause the magnetic head to continue track feeding during the two vertical synchronization periods, the vertical synchronization signal portion of the video signal at this time is normal, and the insertion command l is also output from the system control circuit 6. Because it is not
The video signal a becomes the video output f as it is and is outputted from the pseudo V-sync insertion circuit.

As described above, according to this embodiment, by extracting the vertical synchronization signal from the video signal and replacing the pseudo V sync delayed by 1V with the vertical synchronization signal of the video signal that has become inaccurate due to track feeding, the screen does not flow, and the screen does not shake vertically due to the allowed ±2H.
Even if you quickly advance each track while playing back an image, there is no unsightliness caused by one screen shaking up and down.

Effects of the Invention As described above, according to the present invention, the vertical synchronization signal separated from the reproduced signal is delayed to create a pseudo synchronization signal, and this is replaced with the vertical synchronization signal disrupted by track feed, so that even if the track is sent, , it is possible to obtain the excellent effect that vertical shaking of the screen due to the standard tolerance of ±2H does not occur.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a video signal recording and reproducing apparatus according to an embodiment of the present invention, FIG. 2 is a waveform diagram of each part of FIG. 1, and FIG. 3 is a configuration diagram of a conventional video signal recording and reproducing apparatus. FIG. 4 is a waveform diagram of each part of FIG. 3. 1...Magnetic sheet, 2...Magnetic head, 4...Stepping motor%6...
System control circuit, 7... Video signal processing circuit,
8...Pseudo V sink insertion circuit, 9...
Pseudo V-sync generation circuit, 11... synchronous signal separation circuit, 12... synchronous signal processing circuit.

Claims (1)

[Claims] a magnetic sheet having a plurality of concentric magnetic tracks;
a magnetic head that is movable in synchronization with the rotation of the magnetic sheet and records and reproduces a video signal on a magnetic track of the magnetic sheet; and a synchronization signal that separates a vertical synchronization signal from the video signal reproduced from the magnetic track. a separation circuit, a synchronization signal processing circuit that outputs a synchronization delay signal delayed by a predetermined time from the separated vertical synchronization signal, and a pseudo V-sync generation circuit that outputs a pseudo vertical synchronization signal obtained by delaying the synchronization delay signal by a predetermined time; It is characterized by comprising a pseudo V-sync insertion circuit that switches the pseudo vertical sync signal with the vertical sync signal of the video signal, and switches the pseudo vertical sync signal with the vertical sync signal of the video signal when the magnetic head moves. Video signal recording and playback device.