JPS6192473A - Time axis correction circuit - Google Patents

Abstract

PURPOSE:To prevent deterioration in quality of reproducing information and to reduce the cost by using one of time axis correcting means applying time axis correction respectively to the 1st and 2nd information signal recorded on a recording medium as other delay means. CONSTITUTION:At the still picture reproducing mode, switches 11, 31, 32, 33 are changed over to the position of contact S, and a composite video signal is fed to a time axis correcting means 2 from a time axis correcting means 4. A signal of a fixed frequency 3fc is fed to the time axis correction means 2 from the switch 33, the composite video signal subjected to 1H delay is added or subtracted to/from the composite video signal not subjected to 1H delay via the switch 32, a luminance signal is outputted from an adder 21 and a color signal is outputted from the subtractor 22 respectively. Then a color signal inverted by the inverter 9 and a color signal not inverted are inputted alternately to an adder 8 via a switch 10 switched at every generation of a jump pulse, added with a luminance signal from the adder 21 and outputted via the switch 11.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention corrects the time axis of an information signal reproduced from a recording medium on which at least two or more types of information signals are recorded, such as a video disc player or a video tape recorder. The present invention relates to a time axis correction circuit.

[Prior Art] For example, a video disc records at least two types of information signals: an audio signal and a video signal.
The figure shows the configuration of a conventional circuit for time axis correction. In the figure, reference numeral 1 denotes an RF amplifier that amplifies a reproduced RF signal reproduced from a pickup (not shown) and separates it into an audio RF signal and a video RF signal. The time axis of the separated audio RF signal is corrected by a time axis correction means 2 consisting of a variable delay line such as a CCD or BBD, and the signal is output to an audio detector (not shown).

The video RF signal is detected by an FM detector 3 to become a composite video signal, and after the time axis is corrected by a time axis correction means 4 similar to the time axis correction means 2, it is input to a low pass filter 5 and a band pass filter 6. It has become so. The low-pass filter 5 is, for example, 3M1 (z
It has a cutoff frequency of , and removes a relatively high frequency color signal (C signal) from the composite video signal, and extracts a luminance signal (Y signal). 7 is a delay circuit that gives a predetermined delay time to the luminance signal in order to adjust the timing, and the delayed luminance signal is input to the adder 8. For example, the color signal extracted from the composite video signal by the bandpass filter 6 having a center frequency of 3.58M& is inverted in phase by the inverter 9, or is sent to the adder from the switch 10 without passing through the inverter 9 and without inverting the phase. 8 is input.

The switch 11 is configured to selectively output either the signal obtained by adding the luminance signal and the color signal by the adder 8 or the signal from the time axis correction means 4. A servo circuit 12 separates a horizontal synchronization signal from the output signal, compares the phase with a signal of a predetermined fixed frequency from a reference oscillator, and outputs an error signal to the voltage controlled oscillator 13. The voltage controlled oscillator 13 converts the clock signal of the phase corresponding to the error signal into the time axis correction means 2.
It is designed to output to 4.

In the normal playback mode, the switch 11 is switched to the contact P side, and the audio RF signal separated from the playback RF signal is supplied to the audio detector via the time axis correction means 2, where it is detected and output. be done. On the other hand, the video RF signal is detected by the FM detector 3 to become a composite video signal, and the time axis correction circuit 4. It is output via the contact P of the switch 11. Further, the time axis error of this output signal is detected by the servo circuit 12.

Since the oscillation frequency of the voltage controlled oscillator 13 changes in response to this error, the time axis correction means 2.4 corrects the time axis error of the audio and video signals.

For example, when the still image reproduction mode is selected, the switch 11 is switched to the contact S side.

In the still image reproduction mode, the pickup repeatedly jumps back one track each time a disk (not shown) rotates once. Assuming that an NTSC video signal is recorded at a rate of one frame (odd frame) per round of the disc, the phase of the luminance signal is continuous and in phase before and after the jump, but the phase of the chrominance signal (
The phase of the color subcarrier) changes by 180 degrees and becomes discontinuous. As a result, if the video signal is output in the same way as in normal playback mode, the monitor's APC (Automatic Phase Control) circuit's response capability is not very fast, so hue unevenness will occur at the top of the screen. ,
Switch 1 is activated by the jump pulse generated for each jump.
o is switched, and only the phase of the color signal is inverted for each jump to ensure phase continuity.

However, since this circuit has a configuration in which the luminance signal is separated by the low-pass filter 5, the band cannot be widened in principle, resulting in deterioration of resolution and loss of image quality.

In order to eliminate this drawback, a structure as shown in FIG. 3 has been conventionally used. In the same figure, the second
Portions corresponding to those in the figures are designated by the same reference numerals, and detailed description thereof will be omitted.

In this circuit, a luminance signal is processed by a delay circuit 20 that delays the input signal by IH (H is the period of the horizontal synchronizing signal), an adder 21 and a subtracter 22 that add or subtract the delayed signal and the undelayed signal. and color signals are separated. That is, in the IH-delayed signal and the non-delayed signal, the luminance signal is in phase, but the color signal is in opposite phase.

As a result, the color signal component is canceled out in the adder 21, and the luminance signal component is canceled out in the subtracter 22, so that
The adder 21 outputs a luminance signal, and the subtracter 22 outputs a chrominance signal. Other operations are second
This is the same as in the figure.

[Problem that the invention seeks to solve]

However, in the circuit shown in Figure 3, the luminance signal and color signal are separated by a comb-shaped filter circuit configuration using an IH delay circuit, which limits the band and degrades the resolution. Although the drawback of the circuit shown in FIG. 2, such as the loss of image quality, can be eliminated, there is a drawback that one additional delay circuit is required, resulting in high cost.

[Means for solving problems]

FIG. 1 shows the configuration of a time base correction circuit according to the present invention.

In this figure, parts corresponding to those in FIGS. 2 and 3 are denoted by the same reference numerals, and detailed description thereof will be omitted. In this circuit, the audio RF signal is switched to switch 3.
The signal is inputted to the time axis correction means 2 via the contact point P of 1.

Further, the output of the time axis correction means 4 is supplied to the contact S of the switch 31. The output of the time axis correction means 2 is supplied to the adder 21 and the subtracter 22 via a contact S of a switch 32. Sui.

Contact P of switch 32 is open. Further, the output of the voltage controlled oscillator 13 is applied to the time axis correction means 2 via a contact P of a switch 33. The contact S of the switch 33 is supplied with a signal of a predetermined fixed frequency from a reference oscillator (not shown).6 The frequency is such that the signal input to the time axis correction means 2 is delayed by about IH. For example, if the number of COD stages constituting the time axis correction means 2 is 678.5 stages and the IH is approximately 63 μs, then 3 fc (fc is the frequency of the color subcarrier, for example, 3.58 MHz) is selected to be output. Become. Furthermore, in this circuit, the input to the servo circuit 12 is taken directly from the output of the time axis correction means 4 without going through the switch 11, but as in the case in FIG. You can also choose to take it.

[Effect]

The operation will now be explained. During normal play operation, each switch 11, 31, 32, 33 is switched to the contact P side. The operation at this time is the same as that described above; the audio signal is subjected to time axis correction by the time axis correction means 2 and outputted to the detector, and the video signal is subjected to time axis correction by the time axis correction means 4. Output.

In the still image playback mode (the same applies to the double speed playback mode in which the pickup jumps, etc.), the switches 11, 31, 32, and 33 do not switch to the contact S side. As a result, the time axis correction means 2 uses audio RF.
The signal is no longer supplied, and instead, a composite video signal output from the time axis correction means 4 is supplied.

At this time, a fixed frequency signal of 3fc is applied as a clock from the contact S of the switch 33 to the time axis correction means 2, so the time axis correction means 2 delays the input composite video signal by about the time IH. It operates as a delay means for output. At this time, the audio signal output stage (not shown) is squelched, so that noise and the like are not output as audio. The IH-delayed composite video signal is sent to the adder 21 and the subtracter 22 via the contact S of the switch 32.
and is added to or subtracted from the composite video signal without IH delay. As a result, as described above, the adder 21 outputs a luminance signal, and the subtracter 22 outputs a color signal, and the color signal whose phase is inverted by the inverter 9 and the color signal which is not inverted without going through the inverter 9 are separated. ,
The jump pulse is alternately inputted to the adder 8 via the switch 10 which is switched every time the jump pulse occurs, and is added there to the luminance signal from the adder 21, and the contact S of the switch 11 is input to the adder 8.
Output via . At this time, the composite video signal that is the output of the time axis correction means 4 is input to the servo circuit 12, and an error signal corresponding to the phase difference with the reference synchronization signal is supplied to the voltage controlled oscillator 13.
The time axis correction means 4 is controlled by the clock signal issued by the time axis correction means 3.

Time axis errors in the composite video signal are corrected. At this time, the contact of the switch 33 has been switched to the S side,
The output signal of the voltage controlled oscillator 13 is not supplied to the time axis correction means 2.

Although the above description has been made using a video disc player as an example, the present invention is not necessarily limited to this.

〔effect〕

As described above, in the present invention, when the phase of the signal becomes discontinuous due to a jump operation, etc. in still image playback mode, double speed playback mode, etc., the first and second
Since one of the time axis correction means for correcting the time axis of each information signal is used as the delay means of the other, the quality of the reproduced information does not deteriorate, and the portion surrounded by the dotted line in FIG. 1 (switch 10.32) , the adder 8, 21, the subtracter 22, and the inverter 9) can be easily integrated, and the cost can also be reduced.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of the time axis correction circuit of the present invention, Fig. 2 is a block diagram of a conventional time axis correction circuit, and Fig. 3 is a block diagram of another conventional time axis correction circuit.・RF amplifier 2.4...Time axis correction means 3...FM detector 5...Low pass filter 6...Band pass filter 7.20...Delay circuit 8.21...Adder 9・・・
・Inverter 10.11.31.32.33...Switch 12...
・Servo circuit 13...Voltage controlled oscillator 22...Subtractor or higher

Claims (8)

[Claims] (1) A first correction means for correcting the time axis of the first information signal reproduced from the recording medium, and a second correction means for correcting the time axis of the second information signal reproduced from the recording medium. ,
separation means for separating the second information signal whose time axis has been corrected by the second correction means from a signal delayed by a predetermined time and a signal not delayed; , in the first operation mode, the first or second
The first or second correction means is controlled in response to the time axis error of the information signal, and the first correction means corrects the first information signal, and the second correction means corrects the second information signal. The time axis of each information signal is corrected and outputted, and in the second operation mode, the second information signal whose time axis has been corrected by the second correction means is outputted as the first information signal. Instead, the second information signal is input to the first correction means, the second information signal is delayed by the first correction means by a time approximately corresponding to the predetermined time, and the delayed second information signal is A time axis correction circuit characterized in that the input is input to a separating means. (2) The time axis correction circuit according to claim 1, wherein the first and second correction means are CCDs. (3) The CCD is driven by an output signal of a voltage controlled oscillator that oscillates in response to a time axis error signal of the second information signal in the first operation mode, and is driven by a predetermined signal in the second operation mode. 3. The time base correction circuit according to claim 2, wherein the time base correction circuit is driven by a fixed frequency signal. (4) The time axis according to claim 1, 2, or 3, wherein the first information signal is an audio signal, and the second information signal is a video signal. correction circuit. (5) A patent claim characterized in that the first information signal is an audio signal, the second information signal is a video signal, and the fixed frequency is approximately three times the frequency of the color subcarrier signal. The time axis correction circuit according to item 3. (6) The time axis correction circuit according to claim 4 or 5, wherein the second operation mode is a still image reproduction mode. (7) The time axis correction circuit according to claim 4 or 5, wherein the second operation mode is a double speed playback mode. (8) The time axis correction circuit according to any one of claims 4 to 7, wherein the separating means separates a luminance signal and a color signal from the video signal.