JPS6042995A - Television receiver - Google Patents

Abstract

PURPOSE:To obtain a pattern without jitter even when a sampling clock locked to a burst signal is used by calculating and regenerating a luminance signal into a data at a position aligned in phase geometrically with a horizontal synchronizing signal, in phase difference between a horizontal pulse and the inputted horizontal synchronizing signal. CONSTITUTION:Operating devices 14, 15 executing arithmetic processing the luminance signal Y and a color difference signal C-Y subject to analog-digital conversion and outputted from a comb line filter 2 so as to obtain a data at a position aligned geometrically with the horizontal synchronizing signal are provided by means of a horizontal phase error data obtained by filtering an output of a horizontal phase detecting circuit 9 detecting the phase difference between the horizontal pulse outputted from a variable frequency divider 11 and the horizontal synchronizing signal from a synchronizing separator circuit 8 at a low pass filter 12. In the operation device 14, the difference between digital data of adjacent luminance signals from the comb line filter 2 is derived at a difference circuit 14b, the gain of the difference data is controlled by the horizontal phase error data at a variable gain control circuit 14c and the difference data whose gain is controlled at each line is added to the original luminance signal at an adder circuit 14d.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a technology receiver in which video signals are digitally processed and reproduced.

The structure of conventional examples and their problems In recent years, advances in digital technology and semiconductor technology
Attempts were made to make the circuits of color television receivers digital, and efforts were being made to integrate circuits into single circuits and develop new functions.

Of course, since the signal processing is digitized, the analog-to-technical converter that digitizes the composite video signal and the digital-to-analog converter that converts this digital signal back into an analog signal are powerful as X)i, but the circuit In terms of blocks, it is constructed by digitizing the blocks of a conventional analog television receiver. However, the generation of the basic clock signal that operates the digital system, the frequency division based on that clock signal, and the vertical synchronization part of the digital TV are
, is a J-length circuit.

FIG. 1 is a basic block diagram of a conventional television receiver that performs digital processing. The composite video signal, which is an analog signal, is first processed through an analog-to-digital converter (hereinafter referred to as A-
The digital video signal is subjected to analog-to-dental conversion by a D converter (referred to as a D converter) 1, and the digital video signal is separated into a luminance signal Y and a color difference signal CY by a comb filter 2. At this time, the sampling clock used for A-D conversion is an integer multiple of the frequency of the burst signal, and if the burst signal is in sync with the frequency, color reproduction becomes easy. In the case of 4 times the signal, R-Y data and B
-Y data can be obtained by simply extracting C-Y takes alternately in time, and the process has the advantage of being performed by a simple circuit. This theory is already well known and will not be elaborated here.

This sampling clock uses the oscillation output of the voltage controlled oscillator 7. In order to make this sampling clock a clock locked to the burst signal, the burst gate circuit 3 extracts the burst signal from the color difference signals C and -Y output from the comb filter 2, and then the burst signal is extracted by the burst phase detection circuit 4. The phase of the burst signal is detected, this detection output is filtered by a low-pass filter 6, and then a digital-to-analog transformer (hereinafter referred to as D
-A converter) 6 performs tessital-to-analog conversion and adds it to the voltage controlled oscillator 7 to control its oscillation frequency and phase. This sampling clock also serves as a master clock for other digital circuits.

On the other hand, the synchronization signal is divided from the A-'D converted composite video signal by the synchronization pre-distribution circuit 8. They are added to the Hiraishi filter 10 respectively.

The horizontal position detection circuit 9 compares the phase of the horizontal synchronization signal obtained from the synchronization separation circuit 8 with the horizontal pulse H output from the variable frequency divider 11, and transmits the old Lj difference data by that much A" to the low-pass filter 12. The variable frequency divider 11 for horizontal pulses is controlled by adding it to the variable frequency divider 11 through 11. The frequency of the oscillation output is divided to create a horizontal pulse H.The frequency divider 13 is used to create a vertical pulse V, and the vertical synchronization signal obtained from the vertical filter 1o is used as a trigger to generate a horizontal pulse H. A vertical pulse V is created by dividing the frequency twice the horizontal frequency obtained.

The above circuit has good accuracy when receiving a composite video signal that satisfies normal correct standards, and the circuit configuration is simple, which has four advantages, and many of the current digital one-way Ten Vision receivers use this circuit. method is adopted. However, in the case of an irregular signal in which the relationship between the chroma signal and the horizontal frequency is not determined, the master clock is synchronized with the burst signal, and the horizontal output pulse H causes jitter at the sampling clock interval. . This causes the screen to shake, and also causes screen sickness when the luminance signal Y and color difference signal C-Y are stored in the frame memory and are not retrieved again by the system. It shows the relationship between the video signal and the sampling point, with the Y direction showing the amplitude and the X direction showing the time. Figure 4 shows a case where the burst signal and the horizontal frequency have a fixed relationship. Here, N , N
+1, N+2, N+3, . . . indicate the numbers of sampling points from the start of each line. Figure 4 A'
is the case where the relationship to Figure 4 is reproduced to l]J old r11,
The geometrical image f\('( is correct 1゜Figure 4B is,
Figure 4 shows the relationship between the video signal and the sampling point as in the case of humans, but the burst signal and the horizontal frequency are constant.
In the case where there is no pedigree relationship, the sampling points gradually shift as shown by the circles. Figure 4B' shows this i
l! ! When 11f is generated on i/u, the horizontal position is determined by the output of the master clock (sampling clock) divided by a variable frequency divider, so the sampling point is geometrically determined as shown by the O mark. 713 is arranged correctly. However, as shown by the solid line, the image is not represented geometrically correctly and looks chic. Now that the number of video playback devices such as home video tape recorders and video disc players is increasing, there is an urgent need to take countermeasures against this phenomenon.

Purpose of the Invention The present invention is intended to eliminate the above-mentioned drawbacks of the conventional technology, and to compensate for the reception of a video signal whose horizontal frequency is not in a fixed relationship with the burst signal, thereby preventing screen jitter from occurring. The purpose is to obtain a Ten Vision receiver.

Structure of the Invention The present invention uses a sampling clock locked to a burst signal to convert a composite video signal from analog to digital, and also divides the frequency of the sampling clock by 1 to obtain horizontal pulses. In,
The phase difference between the horizontal pulse and the input horizontal synchronization signal is detected, and at least the luminance signal of the analog-to-digital converted luminance signal and two color difference signals is geometrically converted into the horizontal synchronization signal by detecting the phase difference between the horizontal pulse and the input horizontal synchronization signal. This method performs calculations on data at positions where the phase is consistent and reproduces it, and it is possible to always obtain an M raw image without any sick.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 2 and 3. In FIG. 2, blocks that are the same as those in FIG. 1 are given the same number.

The difference between FIG. 2 and FIG. 1 is that the horizontal pulse output from the variable frequency divider 11 and the horizontal synchronization signal position (·lj; The output of the detection circuit 9 is filtered by the low-pass filter 12, and the data is analog-to-digital converted and output from the comb filter 2 as fL'J1111 degree signal Y.
and the color difference signal C1-Y as data at a position geometrically aligned in phase with the horizontal synchronization signal Q.

rM'! l;1. vessel 14
．． There are 15 plans set up.

The horizontal phase detection circuit 9 is made up of 414 multipliers that multiply the synchronization signal by the horizontal/
To increase the accuracy of eye detection, the synchronization signal uses data on its rising and falling slopes. That is, the above synchronization signal is digital data that is extracted from the composite video signal after analog-to-digital conversion, and also includes the signal IJh'i, and the horizontal phase of this signal and the signal i1/,7 Multiplication is performed in the detection circuit 9. As a result, horizontal phase error data having a higher viscosity than the sampling interval is obtained from the horizontal phase detection circuit 9. This fourth error data is added to the low-pass filter 12. Then, the lower bit of the output of the low-pass filter 12 is the sampling interval l (i', position 1 with a resolution of 4 or less) information. The data marked with an X is interpolated from the sampling data indicated by .

A specific example of the configuration of the arithmetic units 14 and 15 is shown in FIG. The arithmetic unit 14 in FIG. 3 shows only the one corresponding to the luminance signal, and the input luminance signal is output from the launch circuit 14a that holds the input luminance signal at -sampling intervals, the human luminance signal -1'9, and the latch circuit 14a. When a difference circuit 1 that calculates the difference between the luminance signal and the luminance signal is inserted, it is configured with a multiplier using a multiplier, for example, and uses the difference data. 4) by horizontal phase error data, and an adder circuit 14d that adds the data output from the variable gain control circuit 14G and the original input luminance signal.

The luminance signal from the comb filter 2 enters the latch concave path 14a and the differential circuit 14b, and the digital data of adjacent luminance signals, for example, N and N+, are input into the differential circuit 14b.
1. 'Take the difference between N-1-1 and N-1-2・,
The gain 1j+ of this difference data is controlled by the horizontal position A-2 error data in the next II2 variable gain control circuit 14C. This means that a coefficient is set for each line j++ by the horizontal level 4.11 error data, and the gain-controlled difference data for each line from the variable gain control circuit 14C is added to the original source in the addition circuit 14d. By adding the brightness signal to the brightness signal of 1., the output of the positive signal 1. shown by the cross mark in FIG. 4B is obtained. It is possible to obtain the latest newsletter data. (7) According to the configuration of the lever, the horizontal position is A
1) A stable decimal type television receiver with a jitter-free screen can be obtained. of course,
Since a sampling clock locked to the burst signal is used, the advantage that color demodulation can be performed with a simple circuit configuration is not lost.

Note that the horizontal phase jitter can be corrected with any degree of precision by increasing the precision of the multipliers constituting the horizontal phase detection circuit 9. Unfortunately, it is also possible to perform thick correction on the color difference signal using the same arithmetic unit as shown in Figure 3, but since color difference signals usually have a narrow frequency band, there is no problem even without correction. It's something that doesn't exist.

Effects of the Invention According to the present invention ψJ, it is possible to obtain a digital television receiver in which no jitter occurs in the horizontal phase even though a clock locked to a burst signal is used as a sampling clock. Therefore, it has the advantage that new functions using memory, such as recording video images in frame memory, can be easily developed.

[Brief explanation of the drawing]

Fig. 1 is a basic block diagram of a conventional decile type television receiver, Fig. 2 is a block diagram of a television receiver according to an embodiment of the present invention, and Fig. 3 is a specific example of the arithmetic unit in Fig. 2. Block diagram showing an example, FIG. 4 17.
1 and 2 are diagrams for explaining the conventional problems and the operation of the embodiment of the present invention. 1...A Di exchange gB, 2... Comb filter,
3... Burst gate circuit, 4... Burst detection circuit, 5, 12... Low pass filter, 6... D-A converter, 7...・Voltage controlled oscillator, 8... Synchronization separation circuit, 9... Horizontal phase detection circuit, 11... Variable frequency divider, 13... Frequency divider, 14.15...・Arithmetic unit. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Figure 3 Horizontal vertical phase Figure 4

Claims (2)

[Claims] (1) means for analog-to-digital conversion of a composite video signal using a sampling clock locked to a burst signal; means for dividing the frequency of the sampling clock to generate a horizontal pulse; A horizontal position III detection circuit for detecting the A-eye difference is provided, and at least the luminance signal converted from analog to digital using the detection output data is calculated into data at geometrically aligned positions of 41'' as a horizontal synchronization signal. A television receiver designed for playback. (2) The television receiver according to claim 1, wherein both the luminance signal and the color difference signal are controlled by the output data of the horizontal phase difference detection circuit.