JP2586639Y2 - Video signal processing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] The present invention relates to a synchronous window generator for generating a pulse-shaped window having a constant width with reference to a normal synchronous signal, and a terminal for generating a pulse generated by the synchronous window generator. Video signal processing comprising: a pseudo-synchronous signal generating unit for generating a pseudo-synchronous signal by a change; and a synchronizing signal switching unit for outputting a pseudo-synchronous signal from the pseudo-synchronous signal generating unit when the synchronizing signal does not appear in the pulse width. The apparatus can correct horizontal / vertical synchronization disturbance even if there is a sudden electric field fluctuation of a TV broadcast wave.

[Industrial applications]

 The present invention relates to a television receiver mounted on a mobile object.

In particular, the present invention refers to a video signal processing apparatus that prevents deterioration of image quality when a received radio wave is shielded and weakened by a building or the like.

[Conventional technology]

Generally a television receiver is added to the antenna
Extract the signal of the channel to be received from the VHF or UHF signal, amplify and detect it, extract the color TV signal, extract the color signal and the synchronization signal from this signal, and receive the image from the color signal. The three primary color signals (R, G, B) necessary to operate the tube are created, and from the synchronization signal, horizontal and vertical synchronization signals are created on the phosphor screen of the picture tube to assemble the same image as the image on the image transmission side. Device. The frequency is exactly 15.734264KHz in the horizontal polarization circuit
However, it is not necessary to achieve a perfect synchronized screen simply by adjusting the phase, and the phases must also be matched. The horizontal synchronization is more susceptible to noise than the vertical synchronization, and the AFC method is generally adopted. FIG. 6 is a diagram showing a conventional horizontal polarization circuit. First, only the horizontal synchronizing signal is extracted from the video signal by the synchronizing separation circuit 41, and the pulse from the flyback transformer 47 is added to the phase comparator together with the sawtooth wave integrated by RC.
The output of the phase comparator 42 is smoothed by a low-pass filter 43, and the oscillation frequency of the VCO 44 is controlled by a control voltage according to the phase difference. The horizontal synchronization signal is output to a horizontal output unit 46 via a horizontal driver 45. The above-mentioned PLL prevents the synchronization from being disturbed and makes it less susceptible to noise. Thus, in order to maintain accurate screen synchronization, the polarization frequencies of the transmitting side and the receiving side are completely matched, and the phase error between the scanning lines in the horizontal direction is, for example, 0.111 μs, and in the vertical direction, within 3 μs, and the resolution is improved. I have.

[Problems to be solved by the invention]

However, television receivers mounted on automobiles, etc. are easily disturbed by the synchronization signal of the received radio wave due to changes in the environment, and the image is easily disturbed, so even if you try to control with the conventional AFC circuit, the synchronization disturbance due to sudden electric field fluctuation In response, there is a problem that this cannot be removed.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a video signal processing apparatus capable of securing a stable synchronization signal against disturbance caused by the environment in view of the above problems.

[Means for solving the problem]

FIG. 1 is a diagram showing the principle configuration of the present invention. In order to solve the above problem, the present invention provides a video signal device including a synchronization window generator 1, a pseudo synchronization signal generator 2, and a synchronization signal switching unit 3. Synchronization window generator generates a pulse-shaped window having a constant width normal synchronization signal V _i as a reference. The pseudo synchronizing signal generator 2 generates a pseudo synchronizing signal based on a change in the edge of the pulse generated by the synchronizing window generator 1.
V _i ′. Synchronizing signal switching unit 3 outputs a pseudo synchronization signal from the synchronization signal generator 2 similar該擬when not the synchronization signal V _i appears on the pulse width.

[Action]

In FIG. 1, according to the video signal processing apparatus of the present invention, a pulse-shaped window having a constant width based on a normal synchronization signal is generated by the synchronization window generator 1 even if the synchronization signal is temporarily lost. Pseudo pseudo sync signal in changing the end edge of the synchronizing signal generating unit 2, the constant width of the pulse V _i 'is generated. Synchronizing signal switching unit 3, synchronization signal V _i and the pseudo synchronization signal V _i 'and is inputted and it is determined that the synchronization signal V _i is not input pseudo sync signal V _i' is as the synchronizing signal is output. When there is a regular synchronization signal V _i , the pseudo synchronization signal V _i ′
Synchronization Since the window generating unit 1 and the regular synchronizing signal V _i is adjusted so as not to shift the timing at pseudo sync signal V _i 'be suddenly sync signal is lost as a reliable synchronizing signal Can play a role.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 2 is a diagram showing a video signal processing device according to an embodiment of the present invention. The configuration of this drawing will be described. This figure shows an antenna 11 for receiving a video signal, a tuner 12 for tuning a radio wave received by the antenna 11 to a predetermined carrier frequency, and an amplification / detection unit for amplifying and detecting a signal selected by the tuner 12. (Video VIF & DET) 13, an analog / digital A / D converter 14 for converting a video signal from an analog signal to a digital signal among the composite video signals of the amplification / detection unit (video VIF & DET) 13, and the A / D converter Table 14
A Y / C separation unit 15 for separating the digital signal from the digital signal into a luminance signal Y and a chrominance signal C;
Matrix circuit that converts color to three primary colors R, G and B
A digital / analog D / A converter 17 for converting digital signals of the three primary colors R, G and B into analog signals;
A synchronizing separator 18 for separating a composite synchronizing signal Csync from the composite video signal of the video VIF & DET unit; and an image receiving unit for synthesizing a video signal from the D / A converter with the composite synchronizing signal to input and form an image. Unit 19 and the features of the present invention, wherein the synchronization separation unit
Synchronization signal stabilizer that stabilizes 18 horizontal and vertical synchronization signals
Including 10.

FIG. 3 is a diagram showing a configuration of a synchronization signal stabilizing unit according to an embodiment of the present invention. Synchronization stabilizer 10 of the figure the synchronization window generating unit 1 for generating a pulse-shaped window of predetermined width with reference to the synchronization signal V _i of the normal pulse terminal edge of that occurred in the synchronization window generating unit (1) A pseudo synchronizing signal generator (2) for generating a pseudo synchronizing signal (V _i ') by a change in the section, and a pseudo synchronizing signal generator (2) when the synchronizing signal (V _i ) does not appear in the pulse width. And a synchronizing signal switching section (3) for outputting a pseudo synchronizing signal. Further, the synchronization window generator 1 includes a clock 4 for generating a quadrupled signal (frequency 4f _sc ) synchronized with a color subcarrier (frequency f _sc ) from which a color burst signal is extracted by a color synchronization circuit (not shown), for example. 4 of the clock signal 4f _sc and the signal count as an input, for example, counting 50 clock the horizontal synchronizing signal, 860 clock, and outputs a timing signal at 910 clock inputs the synchronization signal V _i, the count in the signal a counter 5 to be reset, generates a pulse on this signal the timing signal counting 910 clocks of the counter 5 as an input, when there is no input of the synchronization signal V _i resets the count of the counter 5 in the signal, for example a monostable A counter reset generator 6 composed of a multivibrator and a timing signal of a count value of 860 clocks of the counter 5 are input and The output signal is changed from “H (High) signal” to “L”.
(Low) signal ”and the count value 50
A pulse forming unit 7 comprising, for example, a bistable multivibrator for forming a pulse having a width of ± 50 clocks around 910 clocks by inputting a clock timing signal and changing the output signal from an L signal to an H signal. Further, the synchronous window generator 1 has a comparator 8 to which the AGC signal S _AGL from the tuner 12 and the reference voltage V _ref are input, and an output of the pulse generator 7 when an arbitrary S _AGL > V _{ref in} the comparator 8. And a switch section 9 for turning off the switch. Here, _assuming that the color subcarrier frequency f _sc , the horizontal scanning frequency f _H , and the vertical scanning frequency f _V , f _V = 59.94Hz, f _sc = 3.579545MHz ± 10Hz
It is. The clock input of the free counter 5 and the synchronization signal generation counter 7 is 4 _fsc , but may be 2 _fsc .

FIG. 4 is a diagram showing a configuration of an example of the pseudo synchronizing signal generator of FIG. The pseudo synchronizing signal generator 2 shown in FIG. 1 is connected to the output of the synchronous wing forming unit 1 and differentiates the output E of the pulse forming unit. 22, a waveform shaping circuit 23 for shaping the output signal of the rectifier 22 into the same waveform as the synchronization signal
And

Next, the operation will be described. FIG. 5 is a time chart showing the operation of the synchronization stabilizing section of FIG. FIG. 3A shows the output of the comparator 8. The power supply and the switching of the receiving channel are performed at a sufficiently high input level (AGL level) of the antenna 11, that is, S _AGC > V _ref is secured and the synchronization signal V _i is secured.
, The counting of the counter 5 is started reliably. At the same time, the switch 9 is switched by the H signal output from the comparator 8 to make it conductive. The counting may be started once at first, and the result may be displayed on a display unit (not shown). Further, S _AGC ≦ V _ref may be _satisfied thereafter. S _AGC >
When V _ref is not ensured even once, the switch 9 is turned off by the L signal output from the comparator 8, and the conventional state is maintained. FIG. 4B shows a clock signal 4f _sc supplied from the clock 4 to the counter 5. This figure (c) shows a horizontal synchronizing signal, and the interval H is 910 in terms of the number of clocks.
This is the number of clocks (910 / 4f _sc = 63.5 μsec). The width of the horizontal synchronization signal may be 0.08H. FIG. 6D shows the count value of the counter 5. The counter 5 is reset at the falling of the horizontal synchronizing signal, and starts counting. The count is 91
When 0 clocks are counted, the falling of the next horizontal synchronizing signal is reset, and this operation is repeated. In addition, a noise signal larger than the threshold value L is cut off from the input of the horizontal synchronizing signal to the counter 5 through the threshold, thereby preventing the count reset by the noise signal. FIG. 3E shows an output signal of the counter reset generation unit 6. This output signal is sent from the counter reset generator 6 to the counter 5 every time the counter 5 counts 910 clocks, and resets the count of the counter 5 at its falling edge. When the counter 5 is not reset due to the loss of the horizontal synchronizing signal, the counter 5 is reset by the counter reset generator 6. FIG. 3F shows an output signal of the pulse width forming unit 7.
The pulse width forming unit 7 changes and holds the H signal from the H signal at 860 clocks of the counter 5 and outputs the signal E which changes from the L signal to the H signal at 50 clocks of the counter 5 and holds the same. When the horizontal synchronizing signal is lost, the rise of this output is used as a reference for generating a pseudo synchronizing signal. This pulse width is determined in consideration of the allowable time of the horizontal synchronization signal such as the pool in of the PLL. FIG. 3G shows an output signal of the synchronization signal switching unit 3. Synchronization is passed through the V _i when the incoming horizontal synchronizing signal V _i to the window generating unit 1 in the window, the pseudo synchronization signal of the pseudo synchronization signal generator 2 when not not enter the horizontal synchronizing signal V _i
Output V _i ′.

Although the case of stabilizing the horizontal synchronization has been described above, the stabilization of the vertical synchronization is similarly configured. However, the interval of the horizontal synchronization signal is 910 × 262 + 910/2 = 238875 clocks (23887
5 / 4f _sc = 16.7 msec), the pulse width forming unit 7 changes the signal from the H signal to the L signal at (238875−200) clocks of the counter 5 and holds it. The only difference is that a signal E which is changed into a signal and held is output.

[Effect of the invention]

As described above, according to the present invention, if the synchronization signal does not appear in the width of the pulse generated by the synchronization window generation unit, the pseudo synchronization signal generation unit generates the pseudo synchronization generated by changing the end edge of the pulse. Since the signal is output from the synchronization signal switching unit in place of the synchronization signal, it is possible to correct horizontal / vertical synchronization disturbance even if there is a sudden electric field fluctuation of the TV broadcast wave.

[Brief description of the drawings]

FIG. 1 is a diagram showing a principle configuration of the present invention, FIG. 2 is a diagram showing a video signal processing device according to an embodiment of the present invention, and FIG. FIG. 4 is a diagram showing an example of the configuration of a pseudo-synchronous signal generating unit in FIG. 3, FIG. 5 is a time chart showing the operation of the synchronization stabilizing unit in FIG. 3, and FIG. FIG. 3 is a diagram showing a horizontal polarization circuit of FIG. In the figure, 1... A synchronous window generating unit, 2... A pseudo synchronous signal generating unit, 3... A synchronous signal switching unit.

Claims (1)

(57) [Scope of request for utility model registration] 1. A video signal processing apparatus for processing a synchronization signal (V _i ) separated from a composite video signal, wherein a synchronization window generating section for generating a pulse-shaped window having a constant width based on a regular synchronization signal (V _i ). (1) a pseudo synchronizing signal generating section (2) for generating a pseudo synchronizing signal (V _i ′) by a change in the end edge of the pulse generated in the synchronizing window generating section (1); A video signal processing device comprising: a synchronizing signal switching section (3) for outputting a pseudo synchronizing signal from the pseudo synchronizing signal generating section (2) when the synchronizing signal (V _i ) does not appear.