JPS62287792A - Video disk reproducing device for pal - Google Patents

Abstract

PURPOSE:To obtain a PAL video signal correcting the discontinuity of a color phase into the continuity by executing the phase inversion in accordance with a track jumping concerning the V axis component of a chroma and resynthesizing with a luminance after the luminance and the chroma are separat ed. CONSTITUTION:The luminance and chroma in a reproducing video signal are separated by a low pass filter 10 and a band pass filter 9. A U-axis conponent in a separated chroma signal and the U-axis component are separated by a separating circuit 12. The phase of the separated U-axis component is alternately inverted and non-inverted for a track jumping by an inverter 13 and a changing- over switch 14 and added to the U-axis component by an adder 15. The chroma signal and the luminance signal obtained by adding are added by an adder 16. Thus, the PAL video signal correcting the discontinuity of the color phase into the continuity can be obtained.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a PAL video disc playback device, and particularly to a video disc playback device with variable speed playback functions such as still, flow, and fast. It is most suitable for use in

[Summary of the invention]

At festivals where variable speed playback such as still, fast, and slow is performed while performing track jumps on video discs recorded with PAL video signals, the luminance/chroma is separated from the playback signal, and the U-axis/■-axis components are separated from the chroma. Then, the phase of the V-axis component is inverted or non-inverted for each trunk jump, and the U
In addition to the axis component, a luminance signal is added to maintain the continuity of color and phase (one line alternating inversion of the V-axis component) for each track jump.

[Conventional technology]

In the PAL television system, color framing is performed in which the color phase changes in a cycle of eight fields. Variable speed playback (still, flow, fast, etc.) of video discs recorded with such PAL television signals
When doing so, the track is traced while performing track jumps of one field to several fields. For this reason, the sequentiality of the color frame is lost with each jump, the phase of the color subcarrier shifts in 90° units, and the V-axis
Line-by-line inversion becomes discontinuous.

In order to maintain the continuity of color framing for each jump, conventionally, the subcarrier phase of the reproduced signal was adjusted by changing the reference phase of the time base collector circuit by 90° for subcarriers. Regarding the continuity of axis inversion, after luminance/chroma separation, the V-axis component Ev in the chroma signal EC=Eu +EV is extracted using a comb filter, and -2 times that is added to the original video input signal. For Ec' = (Eu + Ev) 2 Ev
=Eu Ev V-axis inversion operation is performed, and V-axis inversion (Ec') and no inversion (EC) are performed in synchronization with the track jump.
The continuity was maintained by switching between the two (see Japanese Patent Application Laid-open No. 81396/1983).

[Problem that the invention seeks to solve]

In the color framing restoration circuit described above, if the luminance/chroma separation is incomplete, the V-axis inverted signal -2Ev
When adding 2E to the chroma component in the video signal,
The high-frequency characteristics of the video deteriorate due to the luminance component of the opposite polarity mixed in v. Further, when adding -2Ev of the (2) axis component to generate E,', the added -2Ev must match Ev in the chroma component EC of the input video signal in phase and group delay time. If the phase differences do not match within several n5ec, phase inversion due to Ev acid component cancellation will not be performed as designed. However, in reality, a comb-like filter for extracting Ev from Ec is included in the 12Ev derivation path, so it is very difficult to match the phase between Ec in the wideband video signal and the narrowband 12Ev. . If this is to be realized, a complicated phase and delay time adjustment circuit will be required, and unstable factors such as temperature characteristics will also increase.

In view of this problem, it is an object of the present invention to provide a color framing restoration circuit that can obtain the required performance with a simple circuit configuration.

[Means for solving problems]

As shown in FIG. 1, first, luminance and chroma in a reproduced video signal are separated by a low-pass filter 10 and a band-pass filter 9. The U-axis component in the separated chroma signal and ■
A separation circuit 12 separates the axial component from the axial component. The inverter 13 and changeover switch 14 alternately invert and non-invert the phase of the separated ■-axis component for each track jump, and the adder 15 converts the phase to U.
Add to axis component. The chroma signal and luminance signal obtained by the addition are added by an adder 16 to obtain a PAL video signal that maintains continuity of color phase.

[For production]

Since the phases and delay times of the ■-axis and U-axis components added by the adder 15 are almost the same, there is no need to match the phases and delays of both. In addition, since the luminance signal and chroma signal added in the adder 16 have different bands, they do not interfere with each other (even if the luminance signal has a phase shift,
There is no need to match the phase of the chroma signal; if necessary, it is sufficient to simply match the delay time. Therefore, the circuit configuration is simple, the required performance can be obtained, and the stability and reliability of the circuit operation are also high.

〔Example〕

FIG. 1 is a block diagram of the main parts of a playback system of a PAL video disc player to which the present invention is applied.

The reproduced video signal is transmitted through variable delay element 1 constituting the TBC circuit.
, and is led out to the monitor from the normal side of the changeover switch 2. The TBC circuit has a well-known configuration, in which a burst gate circuit 3 extracts a burst signal from the output of the variable delay element 1, a phase detector 4 compares it with a reference subcarrier of a reference oscillator 5, and the error is filtered through a low-pass filter 7. through v
A variable delay element 1 such as a COD is driven by a clock of a variable controlled frequency of the output of Vcos.
Time axis correction is performed to remove jitter from the reproduced video signal.

During variable speed playback such as still, slow, and fast, the selector switch 2 is set to the variable speed side, and a continuous video output with corrected color frame discontinuity for each trunk jump is output to the monitor.

In the TBC circuit, the output of the reference oscillator 5 is ±900, ±1
The signal is applied to the phase detector 4 through an 80° shift circuit 6. A track jump signal is applied to this shift circuit 6, and the reference subcarrier phase is sequentially switched from 00.180° to 1270° every time a jump occurs. This corrects the 90° shift of the color subcarriers for each jump.

The output of the variable delay element 1 is given to a bandpass filter 9, and the extracted chroma component Ec''Eυ+Ev is supplied to a U/V component separation circuit 12.

The separation circuit 12 is a comb-tooth filter consisting of an IH+λ/4 (λ: one subcarrier wavelength) delay line 12a, a subtracter 12b, and an adder 12c. Ev is obtained, and the U-axis component E0 is obtained from the output of the adder 12C. Note that if the delay line 12a is set to IH-λ/4, ELI and Ev of the comb output will be reversed.

The V-axis component Ev is inverted by an inverter 13, and an inverted signal and a non-inverted signal are alternately selected by a changeover switch 14 for each track jump. The selected output is added to the U-axis component E from the separation circuit 12, resulting in Ec "" Eu '! :Ev is returned to the chroma signal. The continuity of the (1) axis reversal due to track jumps is maintained correctly by switching the changeover switch 14 for each jump, resulting in a regular PAL signal.

The first Roma signal E is added in an adder 16 to a luminance signal Y provided from the variable delay element 1 via a low-pass filter 10 and a delay circuit 11 for time adjustment (group delay adjustment). The added output is output from the speed change side of the changeover switch 2 to the monitor.

According to the embodiment shown in FIG. 1, since the luminance signal Y is band-limited by the low-pass filter 10, when it is added to the chroma signal Ec in the adder 16, high-frequency components of Y are mixed into EC. There is no mutual interference and the luminance signal does not deteriorate even if the Further, since the phase rotation of the luminance signal Y is not a problem, if necessary, the delay circuit 11 may be used to perform minute timing adjustment (several tens of nanoseconds) with the chroma system. In other words, the phase relationship between Y and Ec added together in the adder 16 is arbitrary, and there is no need to match the phases of the two.

Furthermore, since the U-axis component EU and the ■-axis component Ev that are added in the adder 15 pass through almost the same path (including the toothed filter), their phases and delay times are almost the same, and when they are added, There is no need to adjust the phase or time.

Note that the U/V separation circuit 12 can be realized with a configuration other than a comb filter. Further, the trunk jump signal may be a signal obtained by comparing the color framing of the reproduced signal with the reference color framing and detecting a deviation between the two.

〔Effect of the invention〕

As described above, the present invention is configured to separate luminance and chroma, then perform phase inversion on the V-axis component of chroma according to a track jump, and recombine with luminance to obtain a PAL reproduction signal. Since the luminance and chroma bands are different during synthesis, they do not interfere with each other, and even if there is a phase mismatch between the two, they can be added (recombined) without any problem. Therefore, it is possible to obtain a PAL video signal in which discontinuities in the color phase (reversal for each V-axis line) are continuously corrected for each track jump with a simple circuit configuration.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the main parts of a PAL video disc player to which the present invention is applied. In addition, in the symbols used in the drawings, 1----------1 variable delay element 2----
−−−−−−−−−−−−−− All changeover switch 3−−−
−−−−−−〜−・−−１−−・−Perst Gate 4−
・・−・−・−・・−・−Phase detector 5−−−−−−−
−・−・−=−−−−One reference oscillator 6−・・・−−−−
−1−・−−−−1・・±90@, ±180@Shift circuit 7−−−−−・−・−1−−−−−−~Low pass filter 8 −m−−−・−・−−m−−−・−V
CO9--------------Band pass filter 10------Low pass filter 11-------------- −・・−・−Delay circuit 12・・・−・−−−−m−−−・・−・・U/V separation circuit 13−・−・−・−・−−−1−−−−～ - Inverter 14 - - - - - - - - - - Changeover switch 15, 16 - - - Adder.

Claims (1)

[Claims] a circuit that separates luminance and chroma in a reproduced video signal;
A circuit that separates the U-axis component and V-axis component in the separated chroma signal, and a circuit that alternately inverts and non-inverts the phase of the separated V-axis component at each track jump and adds it to the U-axis component. 1. A PAL video disc playback device comprising: a circuit for adding a chroma signal and a luminance signal obtained by addition to obtain a PAL video signal maintaining continuity of color phase.