JPS6284679A - Synchronizing signal generator for video printer - Google Patents

Abstract

PURPOSE:To eliminate jitters and to prevent a picture from deviating from the prescribed position by providing a pulse width setting circuit which generates a pulse having a fixed width in synchronization with a synchronizing signal selected by a changeover switch after said switch switching a horizontal synchronizing signal at the time of recording and reproducing. CONSTITUTION:At the time of recording, the horizontal synchronizing signal HDa at the horizontal frequency fH of a television signal can be obtained from a signal inputted to an input terminal 1 by a synchronizing separator circuit 8, and inputted to the pulse width setting circuit 12 through the connection of a horizontal synchronizing signal changeover switch SWA 11 at the time of recording and reproducing. An output signal 12' synchronizing with the HDa from the pulse width setting circuit 12 leads a voltage controlled oscillator VCO 13 to start oscillation, and its output is applied to an A/D converter 3 and a memory control circuit 25 as a clock pulse. In this case, an HD 12' synchronizing with the HDa pulse at the frequency fH temporarily stops the VCO 13's oscillation, which is again started. Thus a jitter-free clock pulse which synchronizes with the HDa at the frequency fH can be available. At the time of reproduction, the oscillation is stopped or resumed with a pulse HDb at the frequency fH generated from an HDb decoder as a reference.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a video printer that can output a still screen or print image using a television signal as a main input signal, and particularly relates to a signal generating device suitable for signal processing. Regarding.

[Background of the invention]

In addition to the conventional television signal generators used in broadcasting stations, there are currently 5sync generators in home video cameras.
It has been adopted as a Signal Generator (hereinafter referred to as SSG) IC. - For example, 1 desk semiconductor data book 7th edition, digital IC “260~2
The IC described on page 65, MN6064R, can be mentioned.

[Problem that the invention seeks to solve]

In the above IC, each output of the horizontal periodic pulse and the vertical periodic pulse can be reset by a reset terminal, and can be synchronized with an external signal. However, the above two types of pulses have an fsc that is 4 times that of the external IC.
(fsc is the color subcarrier frequency) σ) Since it is generated by dividing and decoding the oscillation output of a crystal oscillator with a natural oscillation frequency, if you reset it using the reset terminal, the fsc 1 will increase by four times. Jitter corresponding to one cycle (one clock) occurs.

Therefore, video printers prevent jitter by switching between using a synchronization signal separated from the input signal when recording an input image and a synchronization signal generated inside the printer during playback.

However, at this time, since the pulse width of the synchronizing signal separated from the input signal is not constant, there is a problem that the video position of the input signal and the video horizontal position of the reproduced signal are misaligned on the monitor screen.

SUMMARY OF THE INVENTION An object of the present invention is to provide a synchronization signal generation device for a video printer that is free from jitter and image position shift.

[Means for solving the problem] The above purpose is to switch the horizontal synchronization signal selected by the changeover switch after the changeover switch for changing the horizontal synchronization signal during recording and playback, which is provided to prevent the occurrence of jitter. This is achieved by providing a pulse width setting circuit that synchronously generates pulses of a constant width.

[For production]

Pulse width setting circuit (Ma, during recording, outputs a constant width pulse synchronized with the horizontal synchronization signal separated from the input signal selected by the changeover switch.

During playback, a constant width pulse is output in synchronization with the horizontal synchronization signal inside the video printer selected by the changeover switch, so the pulse width of the horizontal synchronization signal during recording and playback is the same.

No horizontal positional deviation occurs between the input image and the reproduced image.

〔Example〕

Hereinafter, one embodiment of the present invention will be described using FIGS. 1 to 3.

FIG. 1 is a block diagram of a video printer of the present invention.

1 is a video signal input terminal, 2 is an input signal processing circuit, 3
is an A/D (analog-to-digital) converter, and 4 is l(, A
5 is a D/A (digital to analog) converter; 6 is an output signal processing circuit; 7 is an output terminal for a reproduction signal; 8 is a synchronization separation circuit; 9 is the switch (swB), to is the recording/playback switching signal input terminal, and 11 is the horizontal synchronization signal switching switch (
SWA), 12 is a pulse width setting circuit, 13 is a voltage controlled oscillator (VCO) that can control the start and stop of firing, and 14 is a VC
A counter for O output, 15 a decoder that generates fh period pulses from the vCO output, 16 a phase comparator (P, D
), 17 is a low-pass filter (L, 1), F ), 1
8 is a crystal oscillator type oscillator, 19 is a counter that can be externally synchronized with a reset IC, 20 is a decoder that generates horizontal periodic pulses, 21 is a decoder for synchronizing signals for monitor television,
22 is a synchronization signal output terminal.

First, the operation during recording will be explained.

VC during recording (well, switches 8WA11 and 5WB9 in the diagram
are both a by the signal of the recording/playback switching input terminal 10.
When switching to the A/D side, the video signal input to the input terminal 1 is converted into only a video signal by the input signal processing circuit 2.
It passes through an (analog-to-digital) converter 3 and is stored in a memory 4.

In addition, the synchronization separation circuit 8
As a result, a horizontal synchronization signal a;B/ (hereinafter referred to as f(Da)) of the horizontal period fH of the television signal is obtained, and the horizontal synchronization signal changeover switch 5WAII 54 during recording and reproduction is obtained.
- Input from AIE K to pulse width setting circuit 12. Pulse width setting circuit 120HD a Voltage controlled oscillator 13 (hereinafter referred to as VCO) by IfC synchronized output signal 12'
) starts oscillating, and the output of the VCO 13 is sent to the A/D converter 3 and memory control circuit 2 as a clock pulse.
Added to 5. Since this clock needs to be synchronized with l-(Da without the occurrence of jitter and stable in terms of frequency, the oscillation of VCO 13 is performed by HD 12' which is synchronized with the HDa pulse of f!x period. By stopping the oscillation and starting the oscillation again, it is possible to obtain a jitter-free oscillation output that is synchronized with the same period as HDa and fH.
1 oscillator 18 (fsc is the color subcarrier frequency), the counter 19 and HDb decoder 2 are synchronized with HDa by connecting the switch 8WB.
The basic e pulse of fH period generated by VCO1
A phase compensator (hereinafter referred to as P and D) 16 compares the phase of the output of 3 with the pulse generated by a counter 14 and a decoder 15, detects a frequency error, and passes the error output to a low-pass filter (hereinafter referred to as P and F). vC01
The so-called P has a configuration that controls the oscillation frequency of 3.

L, L (Phase Locked Loop
) performs one frequency stabilization. In non-invention, this VCO1
Since the output of No. 3 is used as a clock, the memory No. 11, which has no jitter, is thickened in the memory 4. As the clock frequency, 3 times fsc is often used, but in this example, P
, L, and any frequency can be used depending on the design of L.

Next, the operation during playback will be explained.

8WA11 and S by the signal of the Roku playback input terminal 10.
WB 9 ha b'il! 9UILbo Surtur VC01
3G;! When 8WAII is connected, oscillation is stopped and restarted based on the fH cycle pulse HDb generated by the 14D b decoder 20, and l', L, and L are also set to H at the time of recording.
HD b 2 with the same operation as that based on Da B/
0' as the reference V, and this time synchronizes with i (D b 20' and generates a frequency lock. As a result, the recorded cod picture is read out from the memory 4 and D/A (digital/analog) It is output to the output terminal 7 after passing through the converter 5 and the output signal processing 6.The synchronization signal 18g for the monitor receiver is generated from the °C counter 19 and the decoder 21vc using the output of the oscillator 18 as a reference, and is output to the output terminal 22. At the same time, it is also combined with the output of the output terminal 7. Further, a signal for obtaining a print image is outputted to the output terminal 24 by the print head drive circuit 23.

Here, the pulse width setting circuit 1 of VC Oka during recording and reproduction.
Since the pulse widths of HD a 8' and HD b 20' are the same from 2D, human power No. 18 1' and reproduction signal 7'
It is possible to prevent horizontal positional deviation on the monitor screen of -C.
Monkey. This will be explained using FIG.

1 is the waveform diagram of the input signal, 8' is the synchronous separation circuit output dDa
o) (H-shaped diagram, 12' is the waveform output circuit output HD waveform diagram, 13', 13'' is the clock waveform diagram, 26 is the waveform diagram of the recorded part of the input signal, 6' is the horizontal position shift The reproduced waveform χ is shown.

HD a 8' is synchronously separated from the input waveform 1' at input terminal 10, and added to the pulse 1llIi + setting circuit 12, and as an output, synchronized with the falling edge of the manual shaping and fixed by the pulse width setting circuit 12 - H l with sufficient pulse width. ) Get 12'O
VC (
J13 starts oscillating and obtains the clock 13', and the memory control 25"'(:' is the Mth length from the pJ:i!" of the clock).The output of the K converter 3 is transferred to the memory 4.
In order to record the input signal 1', a recording waveform 26 of a part of the input signal 1' is recorded in the memory 4.

Next, play this ((for playback) l D b20
'If you use it as is, the OVC will be VCO134.
Well, fi 1) The oscillation starts from the rising edge of b20' and the memory controlling fJ is activated. ,I eye memory 4V
The self-bent signal is 44/i. Human power (FI No. 1')
The horizontal position of the fi/raw signal 6' with respect to rc is erroneous (1o, 1o, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 1, 1, , , , , , , , , , , , , , , , , , , , , , , , ,, , , , , , , , , , , , , , , , , s d is being recorded, however, the horizontal position of the fi/raw signal 6 ′ is misaligned with respect to rc, and the oscillation stop and restart of the vCO 13 is controlled by signals having different pulse widths during recording and playback).

In order to prevent this, the present invention (or HD a during recording)
8' and HDb 20' selector switch S during playback
A pulse width setting circuit 12 is provided after WAll to prevent the pulse width from changing between recording and reproduction.

As a result, HD a 8 separated from input signal 1'
Even if the pulse width of ' changes depending on the input signal, the horizontal position of the image on the monitor receiver can be matched between the input signal and the reproduced signal.

FIG. 3 shows how the horizontal position on the monitor receiver shifts.

27 is an example of a monitor image of an input signal, 28 and 29 are examples of a monitor image of a reproduced image with a horizontal position shift, and 30 is an example of a monitor image of a reproduced image without a horizontal position shift. If the horizontal position of the image shifts, the monitor image 28 will be different from the input monitor image 27,
However, if the present invention is used, it is possible to obtain a reproduced image such as a monitor image 30 that is not shifted by one position compared to the input monitor image 27.

Note that the switches SWAII and SWB9 used in the present invention
The pulse width setting circuit 1 may be a general mechanical contact switch or a semiconductor switch that has been frequently used in recent years.
212. 0 [Invention Q) Effect] According to the present invention, when a video printer stores a television signal in a memory, reads it out, and reproduces it on a monitor screen, the input signal and the reproduction High-quality playback image display that does not cause positional deviation from the signal on the monitor screen, and the image display position does not suddenly move, especially when switching the output to the monitor screen in synchronization with recording/playback operations. is possible.

[Brief explanation of drawings]

The eleventh figure is a block diagram showing one embodiment of the present invention. FIG. 2 is a waveform diagram for explaining the present invention in detail. FIG. 3 is an example of a monitor screen showing the effects of the present invention. 11...Horizontal synchronization signal selection switch during recording/playback, (SWA) Fig. 1 Fig. 3

Claims (1)

[Claims] It has a means for taking a video signal as an input signal, A/D converting the input signal and storing it in a memory as a digital signal, a means for outputting the signal stored in the memory as a print image, and a means for reproducing it on a monitor screen. , fH(f
H has means for obtaining a signal with a period (horizontal periodic frequency of the television), and means for generating a signal with a period of fH from the output of an oscillator that oscillates at a stable oscillation frequency. In the video printer device having means for selecting the above two types of fH cycle signals, means is provided to convert the selected fH cycle signal into an fH cycle pulse having a constant width, and this fH cycle pulse is used for A/ A synchronizing signal generator for a video printer, characterized in that it is configured to control oscillation stop and oscillation start of a clock pulse oscillator for a D converter.