JP2517619B2 - Television receiver - Google Patents

Description

The present invention relates to a television receiver, and is particularly suitable for being applied to a digital television receiver having a high image quality improving function.

[Prior Art] Conventionally, as a digital television receiver, a YC separation circuit that uses line correlation and a YC separation circuit that uses frame correlation are installed in parallel, and motion detection is performed by detecting the motion of the image content of a video signal. There is a type in which one of the YC separation circuits is selected in accordance with the signal to achieve good YC separation.

[Problems to be Solved by the Invention] Meanwhile, some recent television receivers process video signals from video tape recorders and video disc players. Such video signals other than television broadcasting have a jitter (time-axis fluctuation) component, and one frame period is longer than a regular one frame period by a predetermined amount. Therefore, the line correlation and the frame correlation are small, and even if the YC separation symbol is switched according to the motion detection signal as described above, it may not be possible to perform proper YC separation.

By the way, in Japanese Patent Laid-Open No. 62-175091, "Color Television Signal Processing Circuit", there is a circuit for detecting a home video signal or a video disc special reproduction signal and switching the signal processing method to improve the image quality. It is disclosed.
However, this one treats the reproduced signal of a home video tape recorder in which the phase of the color burst signal is not inverted between lines as a non-standard television signal, and is not a comb filter using signal correlation, but a low-pass filter. In-line (frequency separation method) YC separation is performed only by a filter and a bandpass filter, and the YC separation method is switched according to the amount of jitter, or YC separation that considers playback signals with abnormal frame periods. However, it was not able to support only some limited video signals.

Further, in JP-A-60-157391 "Luminance signal / Chromaticity signal separation device", it is determined whether the input video signal is an interleaved signal, and if it is an interleaved signal, YC separation is performed by a comb filter. For non-interleaved signals, there is disclosed a device that performs YC separation by a trap method (frequency separation method). However, this only selects the YC separation method depending on whether the input video signal is an interleaved signal,
No careful consideration was given to the type of signal correlation (combination of line correlation method and frame correlation method) on which the comb filter relies, and there was a limit to image quality improvement.

Furthermore, Japanese Patent Laid-Open No. 63-276994 "Signal processing device for digital television receiver" discloses a television receiver which detects whether an input signal is a standard signal or a non-standard signal and switches the YC separation system. Is disclosed. However, in this product, the color subcarrier phase of the still playback signal of the optical video disc player becomes in-phase between frames, and YC separation by the frame correlation comb filter becomes impossible. Focusing on the occurrence of disturbance in the control voltage for burst reproduction, we only switched the YC separation circuit to the line correlation method, and did not have a pure frequency separation method YC separation circuit as an option of the YC separation method. Therefore, there is a problem in that it is not possible to select an optimum YC separation method for a non-standard video signal with large jitter such as a high-speed reproduction signal of a video tape recorder or a special reproduction signal.

The present invention has been made in view of the above points, and a television receiver which is designed to optimally select the YC separation method according to the signal characteristics of the composite video signal and further improve the image quality by good YC separation. It is intended to provide.

[Means for Solving Problems] In order to solve such problems, the present invention provides a frequency separation method YC separation for separating a luminance signal and a chrominance signal included in a composite video signal by utilizing the difference in occupied frequency bands. Section, a line correlation method YC separation that separates the luminance signal and the color signal by using the difference in line correlation, and a frame correlation method YC separation that separates the luminance signal and the color signal by using the difference in frame correlation And a first part of the composite video signal including jitter
A non-standard video signal detecting unit for detecting whether or not the non-standard video signal is a non-standard video signal including the magnitude of the jitter, and a second non-standard video signal in which the composite video signal has an abnormality in a frame period. A second non-standard video signal detection section for detecting whether or not each of the detection signals of the first and second non-standard video signal detection sections is supplied, and the composite video signal is the first non-standard video signal. And the second non-standard video signal, the frame correlation method YC separation unit is selected, and when the composite video signal is the first non-standard video signal including large jitter, the frequency Separation method YC
If a separating unit is selected and the composite video signal is the first non-standard video signal having a small jitter or the second non-standard video signal, the line correlation separation method
And YC separation mode switching means for selecting the YC separation unit.

[Operation] According to the present invention, the first composite video signal includes jitter.
If it does not correspond to the non-standard video signal of No. 1 or the second non-standard video signal having an abnormal frame period, select the frame correlation YC separation unit and the composite video signal contains large jitter. When it is the first non-standard video signal, the frequency separation method YC separation unit is selected, and the composite video signal is the first non-standard video signal including a small jitter, or the second non-standard video signal is used. In some cases, by selecting the line correlation separation method YC separation section, the YC separation method adapted to the signal characteristics of the composite video signal is selected,
Achieve high image quality.

Embodiments Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a television receiver of the present invention, and FIG. 2 is a diagram showing scanning loci of slow and still reproduction modes of an optical video disc player.

In FIG. 1, the video signal VID is converted into digital data through the analog / digital conversion circuit 1 and then converted into YC.
It is given to the separation circuit 2. The YC separation circuit 2 separates the incoming composite video signal into a luminance signal and a chrominance signal and supplies the luminance signal and the chrominance signal to the YC processing circuit 3. The YC processing circuit 3 performs various processing such as ACC processing, color demodulation processing, and contour correction processing on the incoming luminance signal and color signal, and gives them to the scanning line interpolation circuit 4. The interpolation circuit 4 is
Luminance signals and chrominance signals of a virtual horizontal scanning line in the middle of the incoming horizontal scanning lines are formed by utilizing the correlation of the video signals and are given to the time axis conversion circuit 5. The time-axis conversion circuit 5 time-compresses the luminance signal and the chrominance signal having twice the number of lines of the composite video signal obtained by the interpolation circuit 4 and time-compresses them to the digital / analog conversion circuit 6. That is, the scanning line interpolation circuit 4 and the time axis conversion circuit 5
The scanning line conversion circuit is configured by and outputs a luminance signal and a color signal whose resolution in the vertical direction is doubled.

The digital / analog conversion circuit 6 converts the brightness signal and chrominance signal of the incoming digital data into analog signals and supplies them to the matrix circuit 7. The matrix circuit 7 obtains a primary color signal from the luminance signal and the color signal and supplies it to a CRT display device (not shown).

Here, each of the circuits 1 to 6 in the processing path from the analog / digital conversion circuit 1 to the digital / analog conversion circuit 6
Performs processing based on the system clock signal CK from the system clock generation circuit 8.

In the case of this embodiment, the YC separation circuit 2 follows a frequency separation system for separating the luminance signal and the chroma signal on the frequency axis.
YC separation unit 21, YC separation unit 22 that follows the line correlation separation method that separates the luminance signal and the chroma signal by using the line correlation of the video signal VID, and the luminance signal and the chroma signal that uses the frame correlation of the video signal VID And a YC separation unit 23 according to a frame correlation separation method for separating the.

Further, the scanning line interpolation circuit 4 uses a line correlation to form a luminance signal and a chroma signal of a virtual horizontal scanning line, and a line correlation interpolating unit 41 that utilizes a frame correlation to obtain a luminance signal and a chroma signal of a virtual horizontal scanning line. And a frame correlation interpolator 42 that forms a signal.

Furthermore, the system clock generation circuit 8 is
A burst lock clock generator 81 that forms a system clock signal having a predetermined frequency (for example, four times the frequency of the color subcarrier signal) locked to the burst signal based on the VID burst signal, and a horizontal signal separated from the video signal VID. And an H-lock clock generation unit 82 for forming a system clock signal having a predetermined frequency obtained by frequency-multiplying the synchronization signal.

The YC separating circuit 2, the scanning line interpolating circuit 4, and the clock generating circuit 8 having a plurality of circuit parts of different systems are adapted to select an optimum circuit part according to the discrimination result of the video signal discriminating circuit 9. ing. Further, the YC separation circuit 2 and the interpolation circuit 4 select the circuit unit according to the detection result of the motion detection circuit 10 that detects the motion of the image content of the video signal in addition to the determination result of the video signal determination circuit 9. Has been done.

The video signal discrimination circuit 9 is a video signal in which the video signal provided through the analog / digital conversion circuit 1 has a jitter component (hereinafter referred to as a first non-standard video signal).
First non-standard video signal detection circuit 91 for detecting whether or not
And a video signal in which one frame period of the video signal is intermittently or continuously longer than the regular one frame period by a predetermined period (hereinafter referred to as a second non-standard video signal)
And a second non-standard video signal detection circuit 92 for detecting whether or not.

Here, the first non-standard video signal corresponds to, for example, a video signal from a video tape recorder or a capacitance type video disc player. Further, the second non-standard video signal corresponds to, for example, a video signal in the still reproduction mode and the slow reproduction mode of the optical video disc player. In the still reproduction mode and the slow reproduction mode of the optical video disc player, the same track is scanned every frame or every several frames, so when repeatedly scanning, as shown in FIG. When the scanning position arrives at the end of the track, the scanning position is moved in the radial direction (track crossing) to shift the scanning position to the start position of the track, so that one frame time is increased by the movement time. Non-standard video signal.

The first non-standard video signal detection circuit 91 counts the burst lock clock signal for one frame period of the video signal, for example, and based on the difference from the count number for a regular one frame period which is known in advance, the first non-standard video signal detection circuit 91 It is designed to detect non-standard video signals. Here, the criterion for determining whether the first non-standard video signal is large or small 2
In addition to whether the detection signal is the first non-standard video signal, the first non-standard video signal having a particularly large jitter component (for example, the search mode and the special mode in the video tape recorder) is provided. From the first non-standard video signal having some jitter component (for example, a normal mode playback signal of a video tape recorder and a capacitive video disc player). Video signal of
It is also designed to indicate whether or not

Further, the second non-standard video signal detection circuit 82 obtains the difference between the video signal delayed by one frame period and the video signal not delayed, for example, in the vicinity of the edge of the cut pulse, and calculates the difference time. The second non-standard video signal is detected based on whether or not the increment corresponds to the time for moving the track scanning position in the radial direction.

The video signal discriminating circuit 9 represents the non-standard video signal when at least one of the detection signals for the first and second non-standard video signals is significant, and the detection signals for the first and second non-standard video signals are When both are insignificant, a detection signal S1 representing a standard video signal is applied to the system clock generating circuit 8 and the interpolation mode switching circuit 11.

The system clock generation circuit 8 receives the detection signal S1 in the switch circuit 83 that switches between the system clock signal from the burst lock clock generation unit 81 and the system clock signal from the H lock clock generation unit 82. The switch circuit 83 selects and outputs the system clock signal from the burst lock clock generator 81 when the detection signal S1 represents a standard video signal, and outputs the H lock clock generator 82 when the detection signal S1 represents a non-standard video signal. Select and output the system clock signal from.

This selection is made because in the case of a non-standard video signal, the normal one frame period does not correspond to a predetermined number of burst-locked clock signals, so that the processing of each circuit cannot be properly executed. This is because in the case of the standard video signal, the burst lock system clock signal, which is easy to synchronize with the system clock signal in processing such as color demodulation, is prioritized. Interpolation mode switching circuit 11
When the detection signal S1 represents a non-standard video signal, the interpolating circuit 4 selects the inter-line phase interpolator 41 regardless of the motion detection signal S2. When the detection signal S1 represents a standard video signal, the motion detection signal S2 Accordingly, the interpolating circuit 4 is switched so that the line phase interpolating section 41 is selected when the motion detection signal S2 is significant and the frame interphase interpolating section 42 is selected when the motion detection signal S2 is insignificant.

The reason for switching in this way is that when interpolating, it is necessary to use either line correlation or frame correlation, but in the case of non-standard video signals, frame correlation is small, so line correlation is used. This is because, in the case of a standard video signal, the presence or absence of frame correlation differs depending on the presence or absence of motion, so that the presence or absence of motion is referred to.

The detection signals S3 and S4 of the first and second non-standard video signals by the video signal discrimination circuit 9 are given to the YC separation mode switching circuit 12.

When the detection signal S3 of the first non-standard video signal indicates that the jitter component is particularly large, the YC separation mode switching circuit 12 detects the motion detection signal S2 and the detection signal S4 of the second non-standard video signal. YC that follows frequency separation method regardless of content
When the separation unit 21 is selected and the detection signal S3 of the first non-standard video signal indicates that there is some jitter component, or when the detection signal S4 of the second non-standard video signal is significant, the motion is detected. When the YC separation unit 22 that follows the line correlation separation method is selected regardless of the content of the detection signal S2, and the detection signals S3 and S4 of the first and second non-standard video signals are both insignificant,
According to the motion detection signal S2, when the motion detection signal S2 is significant, the YC separation unit 22 that follows the line correlation separation method is selected, and when the motion detection signal S2 is insignificant, the YC separation unit 23 that follows the frame correlation separation method is selected. The YC separation circuit 2 is switched.

In the case of the first non-standard video signal in which the jitter component is particularly large, both the line correlation and the frame correlation are small, and dot interference is conspicuous when the correlation is used. Therefore, the frequency separation method is adopted. In addition, in the case of the first non-standard video signal or the second non-standard video signal having some jitter component, the line correlation is small because the frame correlation is small but the dot interference is not noticeable. In the case of a standard video signal, the line correlation is always present, but the presence or absence of the frame correlation is determined by the presence or absence of motion. Therefore, when there is motion, the line correlation separation system is adopted, and there is no motion. This is because the frame correlation separation method is adopted.

In the above configuration, when the video signal VID arrives,
The video signal discrimination circuit 9 determines whether the standard video signal
And the second non-standard video signal, the detected signals S1, S3, S4 are given to the system clock generation circuit 8, the interpolation mode switching circuit 11, the YC separation mode switching circuit 12, and the motion detection circuit 10 Motion detection is carried out by the, and the detection signal S2 is given to the interpolation mode switching circuit 11 and the YC separation mode switching circuit 12.

Thus, the system clock generating circuit 8 outputs a system clock signal according to the contents of the video signal to each of the circuits 1-6. Further, the YC separation circuit 2 and the interpolation circuit 4 select a circuit section according to the type of video signal and the presence / absence of motion.

In such a state, the video signal VID is converted into digital data in the analog / digital conversion circuit 1 and given to the YC separation circuit 2, YC separated by the YC separation unit selected in the YC separation circuit 2, and then YC separation is performed. Processing such as ACC processing, color demodulation processing, and contour correction processing is performed in the processing circuit 3, and further scanning line conversion is performed through the selected interpolation unit of the interpolation circuit 4 and the time axis conversion circuit 5 to perform digital / analog conversion. The signal is given to the circuit 6 and converted into an analog signal, given to the matrix circuit 7, converted into a primary color signal and given to the CRT display device.

Therefore, according to the above-described embodiment, YC separation can be performed by the optimum YC separation method for the type of the incoming video signal, and a much better image can be obtained as compared with the conventional device.

EFFECTS OF THE INVENTION As described above, according to the present invention, the second non-standard video in which the composite video signal does not correspond to the first non-standard video signal including jitter and the frame period is abnormal. If the signal does not correspond to the signal, the frame correlation method YC separation unit is selected, and if the composite video signal is the first non-standard video signal containing large jitter, the frequency separation method YC separation unit is selected and the composite video signal is selected. First the signal contains small jitter
When the video signal is the non-standard video signal or the second non-standard video signal, the line correlation separation system YC separation unit is selected, so that the high-speed reproduction signal or special reproduction signal of the video tape recorder is For the first non-standard video signal with large jitter, the frequency separation method YC separation section is selected, and line correlation and frame correlation are poor, so YC separation without dot interference is possible. Like the standard playback signal or the playback signal of the electrostatic capacity type video disc player, the first non-standard video signal with small jitter, or the still playback signal or slow playback signal of the optical video disc player, across tracks. For the second non-standard video signal in which the frame period becomes larger than the regular frame period, the frame correlation is small but the dot interference is small. Has a line correlation that is inconspicuous, so that it is possible to perform proper YC separation by the line correlation separation method, and when the composite video signal does not correspond to either of the first and second non-standard video signals described above. ,
It is possible to perform an appropriate YC separation using frame correlation, and by doing so, it is possible to select a YC separation method adapted to the signal characteristics of the composite video signal and achieve an excellent effect such as high image quality.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a television receiver of the present invention, and FIG. 2 is a diagram showing scanning loci of slow and still reproduction modes of an optical video disc player. 2 …… YC separation circuit 3 …… YC processing subject 4 …… Scanning line interpolation step 5 …… Time axis conversion circuit 7 …… Matrix circuit 8 …… System clock generation circuit 9 …… Video signal discrimination circuit 10 …… Motion detection circuit 12 …… YC separation mode switching circuit

 ─────────────────────────────────────────────────── --Continued from the front page Examiner Ryuichi Sekiya (56) References JP 62-175091 (JP, A) JP 60-157391 (JP, A) JP 63-276994 (JP, A) Special Kai 63-292794 (JP, A) JP 63-1281 (JP, A)

Claims (1)

(57) [Claims] 1. A frequency separation system YC separation unit for separating a luminance signal and a chrominance signal contained in a composite video signal by utilizing a difference in occupied frequency band, and a difference in line correlation between the luminance signal and a chrominance signal. And a line correlation type YC separation unit that separates
A frame correlation method YC separation unit that separates the luminance signal and the chrominance signal by using the difference in frame correlation, and whether the composite video signal is a first non-standard video signal including jitter or not. And a second non-standard video signal detection section for detecting whether the composite video signal is a second non-standard video signal having an abnormal frame period. And each detection signal of the first and second non-standard video signal detection units is supplied,
The composite video signal is also second to the first non-standard video signal.
When the composite video signal is the first non-standard video signal including a large jitter, the frequency separation method YC separation is selected. YC selecting the line correlation separation method YC separation unit when the composite video signal is the first non-standard video signal containing small jitter or the second non-standard video signal. A television receiver comprising a separation mode switching means.