JPS6018077A - Processing circuit of field signal - Google Patents

Abstract

PURPOSE:To eliminate skew distortion by replacing a fixed period including a 0.5 horizontal period within a vertical blanking period with the period of a video signal including an artificial horizontal synchronizing signal having a different cycle from an ordinary horizontal synchronizing signal. CONSTITUTION:The output of an SR flip-flop 12 is turned into an artificial horizontal synchronizing signal (h) having a longer cycle by about 5% than a horizontal synchronizing signal by a counter 10. The signal (h) is applied to an analog switch 4 and a counter 13. The counter 13 counts the signals (h) and delivers pulses with the 230th and 240th signals, and these pulses are applied to monostable multivibrator 15. The output (i) of a D flip-flop 16 is switched at the 229.5th and 239.5th cycles of the signal (h). In this case, the video signal is replaced with the signal (h) by a switch 4. This signal (h) is applied to a hosehold TV set and therefore the reproduced pictures can be obtained with no skew distortion without performing any field/frame conversion.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical field to which the invention pertains] The present invention relates to a field signal processing circuit. More specifically, the present invention provides a monitoring device that records one field per revolution of a disc-shaped recording medium, reproduces a signal recorded in this way, or monitors a field signal output from an imaging device in real time, for example. The present invention relates to a field signal processing circuit effective for use in an electronic viewfinder device.

[Prior art]

A still image can be obtained by recording one field of a video signal on a circular trajectory, that is, endlessly, on a recording medium, such as a rotating magnetic sheet, and reproducing this repeatedly.

In this case, in the video signal of the current standard television system, such as the NTSC system, one field consists of 262.5H (H is one horizontal period), and the sheet is rotated in synchronization with the vertical period of the video signal. When recorded, 262.5 H minutes are recorded on the circular trajectory, and when this is reproduced, jumping (this is called skew distortion) occurs in the horizontal period of 0.5 H, which is not desirable.

In order to remove such skew distortion, a conversion circuit that converts a field signal into a frame signal has generally been used.

FIG. 1 is a block diagram showing an example of a conventional field/frame conversion circuit. This circuit includes a reproducing magnetic head 1 coupled to a magnetic disk on which one field image is recorded on one track, an FM demodulator and an amplifier for demodulating and amplifying the FM modulated signal reproduced by this magnetic head 1. Reproduction signal processing circuit 2, this reproduction signal processing circuit 2
A field that controls the analog switch 4 by the synchronization signal from the synchronization separation circuit 5. - Consists of a frame conversion switching pulse generator 6.

The analog switch 4 outputs a frame signal 101 by switching and outputting a long-delay signal and a 0 and 5H delay signal passed through a 0.5H delay line 6 for each field.

A field/frame conversion circuit having such a configuration is 0.
The 5H delay line 6 is required, which makes the configuration complicated, and if a glass delay line is used as this delay line, the volume is
Further, when a CCD delay line is used, a problem arises in terms of power consumption.

Therefore, as a method for removing skew distortion without using a delay line, for example, a method disclosed in Japanese Patent Laid-Open No. 53-66324 has been proposed. This electrically processes horizontal periods 0 and 5 within one field period, but in order to electrically extend the horizontal pulse, a phase modulation circuit for the horizontal pulse is required, resulting in a complicated configuration. It has become.

[Object of the present invention]

The present invention has been made in view of these problems and shortcomings in the prior art, and uses a simple circuit configuration to remove skew distortion and enable field signals to be viewed using a home television. The aim is to realize a processing circuit.

[Summary of the invention]

The device according to the present invention generates a pseudo-horizontal periodic signal having a period different from a normal horizontal synchronization signal period during a period that is not substantially displayed on a television screen, for example, a period including horizontal periods 0 and 5 within a vertical blanking period. This feature is characterized in that the horizontal period of 0.5 is substantially removed by replacing it with a video signal containing .

〔Example〕

FIG. 2 is a block diagram showing an example of a circuit according to the present invention. In this figure, 1 is a magnetic head, 2 is a reproduction amplifier and FM demodulator, 4 is an analog switch, and 5 is a synchronization separation circuit that inputs signals from the reproduction amplifier and FM demodulator 2, and outputs C15ynC and VD multiplied signals. . 7 is a retriggerable monostable multivibrator (hereinafter abbreviated as RMM) with a pulse width of 0.5H (shorter period than IH, for example, about 0.7 to 0.9H). 8
is D F IJ Tsubu flop (hereinafter abbreviated as DF'F)
, 9 is a monostable multivibrator (hereinafter abbreviated as M) with a pulse width of 85 times the period (hereinafter abbreviated as Tsc) of the color subcarrier (3,58ME(z)), and includes, for example, a counter and a flip-flop. It is composed of
Counting the period of the color subcarrier from the outside, 85Ts
The pulse of b is output. 10 is a counter, terminal 1
Using the color subcarrier applied to 03 as a clock,
It has two output terminals that output pulses at the 19th and 240th clocks after the counter is reset. 1
1 is an OR gate that inputs the signal from MM9 and the 240th clock pulse from counter 10; 12 is an SR flip-flop C or lower 5RFP that is set by the 19th clock pulse from counter 10 and reset by the output of OR gate 11; ), 16 is a counter, which uses the output from 5RFF 12 as a clock,
It has two output terminals that output pulses at the 230th and 24th-0th clock after the counter is reset. 14
15 is an OR gate that inputs the 260th and 240th clock pulses from the counter 16, and 15 is an MJ with a pulse width of about 0.5 H that inputs the output pulse from the OR gate 14.
16 is a DFF whose clock is the signal from this MM15.
It is. 102 is a terminal to which a field frame signal in which a part of the video signal obtained from the analog switch 4 is replaced with a pseudo signal is output.

Next, the operation of the circuit configured in this manner will be explained with reference to the timing charts shown in FIGS. 6 and 4. FIG. 6 shows the case where the recorded video signal is an odd field, and FIG. 4 shows the case where the recorded video signal is an eVQn field.

In these figures, (a) is a reproduced video signal, and (b) is a rotational phase signal (PG multiplied signal) that generates one pulse per rotation of the magnetic disk, and this pulse is the point at which recording starts and ends. In this figure, the video signal is recorded so that the PG double signal position is 7H before the VD signal. (
c) and d) are the C05ync and VD signals obtained by synchronously separating the reproduced signals. (E) is the output of MM7, (F) is the output of DFF8, (G) is the output of MM9, (E) is the 5R
Output of FF12, (S) is output of DFF16, (B)
is a signal obtained by replacing a part of the reproduced video signal obtained at the terminal 102 with a pseudo signal, and is sent to the home television.

In addition, in C-5ync shown in (c) in FIGS. 6 and 4, the start of VD in the odd field is O, and each HD
The positions are numbered up to 524.

Now, the VD signal shown in (b) is OH and 262.5H.
When the eye falls, DFF8 is reset and DFF8
The output becomes L level as shown in (v).

When the VD signal rises and the reset of DFF8 is released, the M
The output of M7 rises as shown in (e) fi, DFF
The output of No. 8 changes to H level as shown in (v). DF
When the output of F8 changes to H level, the output of MM9 becomes
As shown in (g), the level changes to H level for a period of 85 Tsc, and the counter 10°15SRFF12. DF
F16 are each reset.

Because the reset of counter 10 is canceled, color/reset is 10
counts the color subcarriers, and at the 19th point, 5RFF
12, and the 24040th shot resets the RFF 12 and also resets the counter 10 itself. Therefore, the output of the 5RFF 12 goes to the L level for 18 Tsc in a 239 Tsc period, as shown in (a). Therefore, since IH is 227.5+ Tsc, (
e) The output of the 5RFF 12 shown in K becomes a pseudo-horizontal synchronization signal with a period approximately 5% longer than that of the horizontal synchronization signal. This pseudo-horizontal synchronization signal is applied to the analog switch 4 and also to the counter 13. The counter 13 counts the pseudo horizontal synchronizing signal shown in (e) and outputs the 2'50th pulse and the 24040th pulse, and this pulse output is applied to the MM 15 through the OR gate 14.

When a pulse is applied to MM15, M
The output of M15 falls, and the output of DFF 16 changes. Note that the reset input of the DFF 16 is used to prevent malfunction. (The output of the DFF 16 shown in Figure 1 is switched at the 2295th period and the 259th and -5th period of the pseudo horizontal synchronization signal. Only during that period, the video signal is analog
The switch 4 replaces it with a pseudo horizontal synchronization signal. Here, the positions 260' and 240' of the pseudo horizontal sync signal shown in (E) are set to match the horizontal sync signal of the video signal, so that switching between the video signal and the pseudo horizontal sync signal is smooth. It will be held in The signal after being switched by the analog switch 4 becomes sharp as shown in FIG. 1), and one field is 262H, which is an integral multiple of the horizontal synchronizing signal. Therefore, if this signal is input to a home television, a reproduced image free of skew distortion can be viewed without performing field-frame conversion.

Note that all operations of this circuit are reset by the vertical synchronizing signal, VD shown in ), and the timing of subsequent operations is determined by the first horizontal synchronizing signal after the equalization period, so there is no drop error). It is also possible to prevent malfunctions due to Further, the writing start and end positions are not affected by the operation of the circuit at any position as long as they are within the pseudo signal busy switching period.

In the above explanation, the period of the pseudo-horizontal synchronization signal was assumed to be a constant period that is about 5 inches longer than that of the horizontal synchronization signal, but depending on the AFC function of the TV, the switching period between the horizontal synchronization signal and the pseudo-horizontal synchronization signal may be different. When switching, skew distortion may be less likely to occur if the periods of the two signals do not differ greatly.

FIG. 5 is an operational waveform diagram of the main parts in this case.

Here, (c) indicates reproduction C15sync % (power indicates a pseudo horizontal synchronizing signal, and (m) indicates a switching signal of analog switch 4.

In this example, the period of the pseudo-horizontal synchronization signal shown in FIG. A pseudo horizontal synchronizing signal is generated so that the period is the same as that of the horizontal synchronizing signal when the signal is switched again.

This further reduces the influence of skew distortion. Of course, the same effect can be obtained by gradually shortening the length and then gradually lengthening it.

In the circuit shown in Figure 2, the circuits that generate the pseudo-horizontal synchronization signals are all digital circuits, so they can be integrated into an IC and integrated into one chip, simplifying the configuration. . Note that the period in which the video signal is replaced with a video signal containing a specific pseudo-horizontal synchronization signal is a period that does not appear on the television screen, such as a vertical blanking period, or a somewhat longer period that does not substantially appear on the television screen. . Furthermore, if the video signal is black as in this embodiment, it will not be noticeable even if it appears on the television screen, so there is no major problem.

In addition, although the above explanation assumes a playback device that applies a field signal recorded on a disk-shaped recording medium to a home television, the form of the medium is not limited to this and is not limited to playback devices. The invention may also be applied to a monitoring device that monitors field signals from a recording device or an imaging device such as an electronic viewfinder.

[Effects of the present invention]

As described above, according to the present invention, a field signal processing circuit capable of removing skew distortion can be realized with a simple circuit configuration without using a delay line or the like.

In addition, each circuit is composed of a digital circuit, and I
It can be converted into C, and is particularly effective when used in viewfinders of portable video equipment.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the configuration of a field/frame conversion circuit showing an example of the prior art, FIG. 2 is a block diagram of the configuration of a circuit according to the present invention, and FIGS. Timing chart showing the operation. FIG. 5 is a timing chart of main parts showing another example of the operation. DESCRIPTION OF SYMBOLS 1...Magnetic head, 2...Reproduction amplifier and FM demodulator, 4...Analog switch, 5...Synchronization separation circuit, 7...RMM18...DFF, 9.15...
MM, 10゜13...Counter, 11.14...Or Gate, 12...5RFF, i6...DFF0 Agent Patent Attorney Sanro Kimura

Claims (3)

[Claims] (1) In a circuit that performs signal processing for recording or reproducing field signals that include a horizontal period of 0.5, or for displaying on a monitor, a certain period that includes the horizontal period of 0.5 is different from the normal horizontal synchronization signal period. A field signal processing circuit characterized in that the horizontal period of 0.5 is substantially removed by replacing it with a pseudo-horizontal periodic signal having a period of 0.5. (2) Change the period of the pseudo horizontal synchronization signal to the horizontal synchronization signal υ
The period is gradually lengthened and then gradually shortened from the time of switching to the horizontal synchronization signal, so that the period becomes the same as the horizontal synchronization signal at the time of switching to the horizontal synchronization signal again. Field signal processing circuit. (3) The period of the pseudo-horizontal synchronization signal is gradually shortened from the time when it is switched to the horizontal synchronization signal, and then gradually lengthened, and the period becomes horizontal when it is switched to the horizontal synchronization signal again. The field signal processing circuit according to claim 1, wherein the field signal processing circuit is made to be the same as a synchronization signal.