JPS59112770A - Horizontal synchronizing pulse signal generator - Google Patents

Abstract

PURPOSE:To remove variation of a horizontal AFC filter signal by using a horizontal AFC gate signal during phase comparison for a pulse signal generator which is used for sampling a character multiplex signal and television and RGB display. CONSTITUTION:A composite synchronizing signal (j) separated synchronously from a composite video signal inputted to an input terminal 30 is applied to a monostable multivibrating oscillator 32 to generate a horizontal periodic signal (k) from which the influence of the vertical equalized pulse signal in the composite synchronizing signal is removed. This signal (k) is applied to a monostable multivibrating oscillator 33, which generates a horizontal AFC gate signal (l) which has pulse width nearly as wide as the horizontal synchronizing signal. A horizontal AFC circuit 34 gates a horizontal synchronizing integral signal (m) by the gate signal (l) and makes a phase comparison to obtain a horizontal AFC signal (n). Therefore, a stable horizontal synchronizing pulse signal appears at the output of a horizontal oscillation circuit 37 even after a vertical equalized pulse section.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is useful for extracting various signals (for example, character multiplex signals) superimposed within the vertical retrace period of a composite video signal, The present invention relates to a device that generates a horizontal synchronizing pulse signal that can be used for RGB (RGB) display.

2. Description of the Related Art Structures of Conventional Examples and Their Problems In recent years, due to rapid advances in semiconductor technology, information transmission and display means using digital signals have attracted much attention. For example, in teletext broadcasting, based on a report by the Radio Technology Council in March 1981, broadcasting (pattern system) is about to begin in the spring of 1981. Furthermore, the implementation of captain services and the widespread use of personal computers (hereinafter referred to as personal computers) are remarkable.

Teletext broadcasting is performed from IOH to 2LH (2
A binary (0'', ``1'') digital signal (referred to as a character multiplex signal) is superimposed on any horizontal scanning period (6) of 12H (each field) from 78H to 284H), and is sent and received. This is a new information medium that displays characters and graphics by combining the above-mentioned signals.The decoding of the character multiplex signal is based on the horizontal synchronization signal obtained from the horizontal synchronization signal of the composite video signal that is multiplexed with the character multiplex signal. This is done by detecting the multiplex position from the pulse signal and the vertical synchronization signal obtained from the vertical equivalent pulse signal.

On the other hand, the above-mentioned teletext broadcasts, captain services, personal computers, etc. display information in the form of images on a television receiver or monitor television (video, RGB i). RG
The screen display in B) is performed using signals obtained from the vertical synchronization signal and the horizontal synchronization pulse signal. this house,
Display in the horizontal direction is performed by a signal obtained from the horizontal synchronization pulse signal.

As described above, the accuracy of the horizontal synchronizing pulse signal has a great deal to do with the accurate extraction of character multiplex signals and the horizontal display on television receivers and monitor televisions (video, RGB). Figure 1 is a block diagram of a conventional horizontal synchronization pulse signal generation circuit, in which (a) is the input terminal for the composite video signal, QI) is the synchronization separation circuit, (a) is the horizontal AFC circuit, and the wire is the horizontal synchronization integral signal input terminal. Input terminal, (
C) represents a filter circuit, (C) represents a horizontal oscillation circuit, and @ represents a horizontal synchronizing pulse signal output terminal. Figure 2 shows the signal waveforms of each block in Figure 1 in the first field of the composite video signal, where (a) shows the sync separation circuit Q])
Output composite synchronization signal waveform, (1)) is horizontal synchronization integral signal waveform input to input terminal (2), (C) is horizontal AFC
Horizontal AFC signal waveform of circuit (2) output, (d) horizontal AFC filter signal waveform of filter circuit (c) output, (e
) represents the horizontal synchronizing pulse signal waveform which is the output of the horizontal oscillation circuit (g). Further, the Arabic numerals in the figure represent the horizontal scanning period number in the first field.

Figure 8 shows the waveforms and their positional relationships of the character multiplex signal multiplexed in the 10th horizontal scanning period within the vertical retrace period of the composite video signal and the pulse signal used to extract the character multiplex signal. (f) is the multiplexed character multiplex signal waveform, (c) is the horizontal synchronization pulse signal waveform whose frequency and phase match the horizontal synchronization signal in the composite video signal, and (h)
is the clamp signal waveform, (i) is the extracted pulse signal for character multiplex signal determination (hereinafter referred to as CRG pulse) waveform, and (g, (h, and i') are the horizontal synchronizing pulse signals (g), respectively. Each of the above signals (g) when the phase of
, Ol) , (i>) and the signal when the phase of (g, (h, i is the horizontal synchronizing pulse signal transmission, respectively) is advanced.

(h) Display the signal waveform corresponding to (i>).

FIG. 4 shows that the phase of the horizontal synchronizing pulse signal shown in FIG. TV receiver and monitor TV (video,
An example of an image of RGB') is shown.

In the conventional horizontal synchronizing pulse signal generator configured in this way, the composite video signal input to the input terminal (A) is
Synchronization is separated in the synchronization separation circuit CI), and the synchronization is separated in the synchronization separation circuit CI).
) is the composite video signal shown in the figure below. On the other hand, the horizontal oscillation circuit (2
) and a horizontal synchronization integral signal (b) obtained by integrating the flyback pulse of a television receiver, etc., is applied to the input terminal (2). The horizontal AFC circuit (a) gates the horizontal synchronization integral signal (b) with the composite synchronization signal (a) and compares the phases, thereby generating the horizontal AFC signal (c).
is obtained. The horizontal AFC signal @(C) thus obtained is smoothed through a filter circuit Q to become a horizontal AFC filter signal (a). In the horizontal oscillation circuit), the horizontal oscillation frequency is set according to the value of the horizontal AFC filter output signal ω), the higher the voltage value is positive, the higher the frequency is oscillated, and the more negative the voltage value is, the higher the frequency is. By oscillating a low frequency, a horizontal synchronizing pulse signal shown in FIG. 2(e) is obtained.

However, in the above configuration, horizontal AF
As shown in the C filter signal waveform (d), the AFCi pressure changes greatly in the 31■ section of 4.5.6 in Fig. 2 (a), the so-called vertical equivalent pulse section, so the horizontal synchronizing pulse signal (e ) changes in frequency. Therefore, the second signal whose phase and frequency match the synchronization signal part of the composite video signal is
The horizontal synchronization pulse signal (e) is shifted in frequency and phase with respect to each horizontal synchronization signal of the composite synchronization signal in FIG. It is about 20H to 80H after the position of the vertical equivalent pulse signal that this deviation subsides and the composite synchronization signal waveform (a) matches the horizontal synchronization signal in phase and frequency.

The horizontal synchronizing pulse signal (
The frequency/phase shift e) has the following problems.

That is, for accurate decoding of a teletext signal in teletext broadcasting, the frequency and phase stability of the horizontal synchronization pulse signal during the vertical retrace period are important. In order to accurately decode the data of the character multiplex signal (f) shown in Figure 3, the CRG pulse signal (i) obtained from the horizontal synchronizing pulse signal must be It is necessary to accurately extract the IN signal (determines the phase of the sampling lock when sampling data) and the FC signal (framing code; determines that the following data is character multiplex signal information). The positional relationship of each pulse signal when accurately decoding a character multiplex signal is the waveform (g), ()j,
(i). On the other hand, the CRG pulse signal obtained by the horizontal synchronizing pulse signal (g') when the phase is delayed within the vertical retrace period in which the character multiplex signal is multiplexed with respect to the horizontal synchronizing pulse signal part (with the correct phase and frequency) (i
1), the first few bits (1 bit in the figure) of the CRI signal of each signal of the 0CRI FC are lost, which interferes with correct decoding of the character multiplex signal. Conversely, the CR obtained from the horizontal synchronizing pulse signal ← (corresponding to Fig. 2 (e)) when the phase is advanced with respect to the above-mentioned correct horizontal synchronizing pulse signal (g)
In sampling using the G pulse signal (i'), the above CR
Of each signal of I and FC, FC (several bits after Fi number (
(1 bit in the figure) is missing, which hinders correct decoding of the character multiplex signal.

In addition, TV receivers and monitor TVs (video, RGB
) When the phase of the horizontal synchronizing pulse signal used for horizontal display of the TV screen shifts due to the above-mentioned reasons, it takes 20 to 80 hours for the phase to become stable, and as shown in Figure 4, the horizontal synchronizing pulse signal is displayed at the top of the TV screen. Distortion may occur. (This figure shows a case where the phase advance of the horizontal synchronization pulse signal is large.) In this way, in the conventional horizontal synchronization pulse signal generator as described above, for example, in teletext broadcasting, it is difficult to decode with an accurate teletext signal. There are also problems such as the upper part of the TV screen being distorted.

OBJECTS OF THE INVENTION The present invention provides a horizontal synchronizing pulse signal generator that can obtain a horizontal synchronizing pulse signal that matches the horizontal synchronizing signal in a composite video signal in both frequency and phase even immediately after a vertical equivalent pulse. With the goal.

Structure of the invention.

The horizontal synchronization pulse signal generation device of the present invention includes synchronization signal separation means for deriving a composite synchronization signal from an input composite video signal;
horizontal periodic signal separation means for deriving a horizontal periodic signal from the composite synchronization signal; phase comparison means for obtaining a horizontal AFC signal by comparing the phases of the horizontal periodic signal and the horizontal synchronization integral signal obtained from the horizontal synchronization signal; A horizontal oscillation circuit that determines an oscillation frequency and phase according to the output signal of the comparison means is provided, and a horizontal synchronization pulse signal whose phase and frequency match the horizontal synchronization signal of the human-powered video signal is obtained from the output of the horizontal oscillation circuit. It is characterized by In addition, as a specific example of the horizontal periodic signal separation means, -! -H to less than IH (H
is a first monostable multi-oscillator with a predetermined pulse width within the range of (horizontal period), and the output of this first monostable multi-oscillator is input and is equivalent to the pulse width of the horizontal synchronization signal specified by the Radio Law. The output of the second monostable multi-oscillator is used as a gate signal for the horizontal AFC circuit.

DESCRIPTION OF THE EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 5 and 6.

FIG. 6 shows a block diagram of a horizontal synchronizing pulse signal generator according to the present invention. In Fig. 5, (to) is the composite video signal input terminal, Op is the synchronous separation circuit, and ) is the first terminal, respectively.
．． Second monostable multi-oscillator, (c) horizontal AFC circuit, (g) horizontal synchronous integral signal input terminal, (to) filter circuit, (b) horizontal oscillation circuit, (to) horizontal synchronous pulse signal Represents an output terminal.

FIG. 6 shows the signal waveform of each block in FIG. 5 in the first field of the composite video signal, and (j)
is the sync separation circuit 0]) output composite sync signal waveform, (k)
is the horizontal periodic signal of the output of the first monostable multi-oscillator (a), (4) is the horizontal periodic signal of the output of the second monostable multi-oscillator)
FC gate signal, (c) is horizontal synchronous integral signal input terminal ■
→Horizontal synchronous integral signal waveform input to →, (n) is horizontal A
Horizontal AFC signal waveform of FC circuit (b) output, (o) horizontal AFC filter signal waveform of filter circuit (to) output,
(p) represents the horizontal synchronizing pulse signal waveform output from the horizontal oscillation circuit (b). Also, the composite synchronization signal waveform (j) in Fig. 6
The operation of the horizontal synchronizing pulse signal generating circuit of this embodiment, which is configured as shown in the horizontal position in the first field, will be described below.

In FIG. 5, the composite video signal inputted to the composite video signal input terminal ) is synchronously separated in the sync separation circuit 0 ]) to become a composite sync signal (j). Composite synchronization signal (
D is added to the first monostable multi-oscillator (a), and
The monostable multi-oscillator (a) latches the signal at each rising edge of the input composite synchronization signal (i), and outputs -HH to I.
Less than H [H is horizontal scanning aperture, approximately iH in Fig. 6 (k))
A horizontal periodic signal (k) having a pulse width of is generated. As shown in the waveform of the horizontal periodic signal (k), the first monostable multi-oscillator (a) generates the vertical equalization pulse signal [4.5.6H in FIG. 6(j)] in the composite synchronization signal. section's vertical equivalent pulse signal] is removed.

The horizontal periodic signal (k) is applied to a second monostable multi-oscillator G). The second monostable multi-oscillator (to) latches the signal at each rising edge of the input horizontal periodic signal (k),
A horizontal AFC gate signal (4) having a pulse width approximately equal to the pulse width of the horizontal synchronization signal in the composite video signal is generated. On the other hand, the horizontal synchronous integral signal obtained by integrating the output signal of the horizontal oscillation circuit (b) and the flyback pulse of a television receiver, etc.) is connected to the horizontal synchronous integral signal input terminal (
added to In the horizontal AFC circuit, the horizontal synchronization integral signal (c) is gated with the horizontal AFC gate signal (1) and phase comparison is performed to obtain the horizontal AFC signal (c).
n) is obtained. The horizontal AFC signal (n
) passes through the filter circuit ) and is smoothed to become a horizontal AFC filter signal (o) with very little variation. The horizontal oscillation circuit (b) determines the oscillation frequency and phase according to the value of the horizontal AFC filter signal (0) and oscillates a horizontal synchronizing pulse signal (p).

In this way, in the horizontal AFC circuit (incorporated), the first . By using the horizontal AFC gate signal (n) derived using the second monostable multi-oscillator (a), the horizontal AFC filter signal (o) is generated by the vertical equivalent pulse signal in the input composite video signal.
It is possible to obtain a stable horizontal synchronizing pulse signal that matches the horizontal synchronizing signal part of the composite video signal in both frequency and phase throughout the field.

In the above embodiment, the horizontal periodic signal separating means is the first.
It consists of a second monostable multi-oscillator (at '0),
This is a discrete circuit, TTL element, semiconductor IC
It is also possible to implement it in a circuit.

As described in the detailed description of the invention, according to the horizontal synchronization pulse signal generator of the present invention, a horizontal period signal is derived from a composite synchronization signal separated from an input composite video signal, and the horizontal period signal and the horizontal synchronization signal are combined. In order to compare the phase with the horizontal synchronization integrated signal obtained from the horizontal oscillation circuit output, the horizontal synchronization f
An excellent effect can be obtained in that it is possible to generate a horizontal synchronizing pulse signal whose phase and frequency match those of the signal.

As a result, it is possible to accurately extract and decode the teletext signals in the teletext broadcasting, and to remove horizontal distortion on the screens of television receivers, monitor televisions, (video, RGB), etc. This can contribute to the spread of multiplex broadcasting and captain services.

[Brief explanation of the drawing]

Figure 1 is a block diagram of a conventional horizontal synchronizing pulse signal generator, Figure 2 is a waveform diagram of the main parts of Figure 1, and Figure 8 is a character multiplex signal waveform and various pulse signal R waveforms used for decoding the character multiplex signal. FIG. 4 is an explanatory diagram of a conventional image example, FIG. 5 is a block diagram of an embodiment of the horizontal synchronizing pulse signal generator of the present invention, and FIG. It is a main part waveform diagram. (l...composite video signal input terminal, υ...synchronization separation circuit, (2) l...first and second monostable multi-oscillators, ■...horizontal AFC circuit, (c) Horizontal synchronization integral signal input terminal, (G) - Filter circuit, (@... Horizontal oscillation circuit, (j)... Composite synchronization signal, (k)...
Horizontal periodic signal, (1)...Horizontal AFC gate signal, 6
rtl...Horizontal synchronous fraction signal, (n)...Horizontal AF
C signal, (o)...Horizontal AFC filter signal, (p)...
...Horizontal synchronization/Mars signal agent Yoshihiro Morimoto Figure 1 ゝ lj Figure 2 Figure 3 ( ( Figure 4

Claims (1)

[Claims] 1. Synchronization signal separation means for deriving a composite synchronization signal from an input composite video signal, horizontal periodic signal separation means for deriving a horizontal periodic signal from the composite synchronization signal, and a horizontal periodic signal and a horizontal synchronization signal. A horizontal oscillation circuit is provided with a phase comparison means for obtaining a horizontal AFC signal by comparing the phases of horizontal synchronization integrated signals obtained from A horizontal synchronizing pulse signal generation device for obtaining a horizontal synchronizing pulse signal whose phase and frequency match the horizontal synchronizing signal of the input composite video signal from the output of the input composite video signal. 2. The horizontal periodic signal separation means is set from 4H to less than IH (H
is a first monostable multi-oscillator with a predetermined pulse width within the range of horizontal period), and the output of this first monostable multi-oscillator is input, and the pulse width of the horizontal synchronization signal specified by the Radio Law is Claim 1 comprising a second monostable multi-oscillator that outputs a signal with the same pulse width, and the output of the second monostable multi-oscillator is used as a gate signal for a horizontal AFC circuit. The horizontal synchronizing pulse signal generator described in .