JPH0683427B2 - Disk scanning device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention scans desired recording information by moving a pickup to an information recording medium such as a video disk in a radial direction faster than a normal reproducing speed. The present invention relates to a device that performs a so-called visual scan operation.

[Conventional technology]

For example, the reproduction of a video disc is performed by the structure as shown in FIG. In the figure, reference numeral 1 is a disk, which is rotated by a motor 2. A pickup 3 irradiates the disc 1 with laser light or the like to reproduce recorded information. The reproduction RF signal obtained from the pickup 3 is demodulated by the demodulation circuit 4 to be a video signal and supplied to the television receiver 5.

In the case of a normal reproducing operation, since the tracking servo loop of the pickup 3 is closed, the pickup 3 is transferred at a relatively slow speed in the disk radial direction, and a good video signal can be obtained. However, during a visual scan operation, such as when searching for a desired screen while looking at the devision receiver, the pickup 3 is moved in the disk radial direction at a relatively high speed. Pickup 3 at this time
The tracking servo loop is closed for a certain section and opened for another section, and this operation is repeated. When the tracking servo loop is closed, the pickup 3 can follow the track of the disc 1, and a good video signal can be obtained. However, if the tracking servo loop is open, the pickup 3 will cross (jump) the track, and the video signal will be defective including noise. FIG. 5 schematically shows these things. The sections A and I are in the reproduction mode, and the sections B to H are in the scan mode. The section C (E, G) is a section which is generated when the tracking mirror (not shown) of the pickup 3 is rotated to the rotation limit, for example, and usually corresponds to several hundred tracks. , Very short in time.

[Problems to be solved by the invention]

By the way, during such a scanning operation, there is no problem in the case of the CAV disc, but in the case of the CLV disc, the phases of the vertical and horizontal synchronizing signals extracted from the reproduction signal are deviated. This is because the information is recorded so that the angular velocity is constant in the CAV disc, so that each sync signal is aligned on the radial line on the disc, whereas in the CLV disc, the information is recorded so that the linear velocity is constant. Is recorded, the sync signals are not aligned on the radial line on the disc. In the case of a CLV disc, theoretically, the phase changes randomly within a range of ± π before and after the sections B and D (D and F, F and H). As shown in FIG. 6, in the case of the CAV disc, the vertical synchronizing signal that continuously arrives at a predetermined cycle is CLV.
In the case of a disc, it does not arrive at every predetermined period and it becomes discontinuous before and after sections B and D (sections C, E, and G are almost ignored in FIG. 6 because the time is short). Available). Therefore, when the CLV disk is scanned, the vertical deflection scanning is disturbed and the screen flows in the vertical direction, which is very unsightly, and it is practically impossible to scan the CLV disk in the conventional apparatus.

[Means for solving problems]

In order to solve the above-mentioned problems, the present invention, based on a synchronization signal extracting means for extracting a reproduction vertical synchronization signal from an input signal and a scan command pulse from the outside, generates a pulse phase-synchronized with the reproduction vertical synchronization signal during non-scan operation. A pulse generating means for generating and outputting, and generating and outputting a pulse phase-synchronized with the reproduction vertical synchronizing signal extracted immediately before the start of the scanning operation, and an output of the pulse generating means are input. A pseudo sync signal generating unit that includes a PLL circuit and generates and outputs a pseudo vertical sync signal that is phase-locked with the pulse, and outputs the pseudo vertical sync signal by adding the pseudo vertical sync signal to the input signal from which the reproduced vertical sync signal is extracted. Addition means, pulse stretch means for extending and outputting the pulse width of the scan command pulse, and output of the pulse stretch means Based configure and a selection means for outputting selectively one of an output signal of said input signal or said additional means.

[Action]

According to the present invention, the synchronizing signal extracting means outputs the input signal from which the reproduced vertical synchronizing signal is extracted to the adding means. The pulse generating means generates and outputs a pulse that is phase-synchronized with the reproduction vertical synchronization signal in the non-scan operation based on the scan command pulse from the outside, and outputs the reproduction vertical synchronization extracted immediately before the start of the scan operation in the scanning operation. The pulse that is phase-locked with the signal is generated and maintained, and is output to the pseudo-synchronization signal generation means. The pseudo sync signal generating means uses the PLL circuit to generate a pseudo vertical sync signal that is phase-locked with the pulse from the pulse generating means and outputs it to the adding means. The adding means adds the pseudo vertical synchronizing signal to the input signal from which the reproduced vertical synchronizing signal is extracted and outputs it. On the other hand, the pulse stretching means stretches the pulse width of the scan command pulse and outputs it to the selecting means. As a result, the selecting means selectively outputs either the input signal or the output signal of the adding means based on the output of the pulse stretching means.

Therefore, the disk scanning device is
Since the image is displayed based on the pseudo input signal to which the pseudo synchronization signal having the stable phase is added, the stable image can be displayed without the image flowing during the scanning operation. Further, when the scan operation shifts to the normal operation, the pseudo sync signal is switched after the phase of the reproduced sync signal sufficiently matches the phase of the reproduced sync signal, so that the screen is not disturbed when the sync signal is switched.

〔Example〕

Next, an embodiment of the present invention will be described with reference to FIGS.

This embodiment is realized by inserting an adapter 10 as shown in FIG. 1 between the demodulation circuit 4 and the television receiver 5 in FIG.

In FIG. 1, reference numeral 11 denotes an input terminal to which a demodulated video signal is input, a contact Y of a switch 12, a vertical synchronization signal extraction circuit 13 that extracts a vertical synchronization signal from the input signal,
Phase detecting means for detecting the phase of the vertical synchronizing signal of the input signal
And 14 vertical synchronizing signal separation circuits 15, respectively. The video signal from which the vertical synchronization signal has been extracted through the vertical synchronization signal extraction circuit 13 is added with a pseudo synchronization signal by the vertical synchronization signal addition circuit 16 and is used as a pseudo input signal by the switch 12
It is designed to be output to the contact X of. A signal having a frequency twice the frequency f _H of the horizontal synchronizing signal, for example, is supplied to the terminal 32 as a reference signal, and this signal is supplied to the frequency dividing circuit 33.
Is divided into 1/525. Therefore, the frequency dividing circuit 33 outputs a signal having the same frequency as the vertical synchronizing signal to the PLL circuit 17. The PLL circuit 17 outputs a signal having a phase corresponding to the signal from the frequency dividing circuit 33. Reference numeral 18 is a mono-multivibrator as a means for generating a pseudo sync signal, and a vertical sync signal addition circuit for applying a pseudo vertical sync signal of 3H (H is a cycle of the horizontal sync signal) corresponding to the vertical sync signal of the input video signal during normal reproduction. Supply to 16.

19 is a terminal, which can be
High level signal when scanning CLV disk
When scanning is not performed, low level signals are supplied. The switch 31 is opened when a high level signal is output from the terminal 19 and closed when it is at a low level. The signal from the vertical synchronizing signal separation circuit 15 is supplied to the reset terminal of the frequency dividing circuit 33.

Reference numeral 20 is a pulse stretch circuit that delays only the falling edge of the pulse signal from the terminal 19. 21 is a switch
An output terminal for supplying a video signal or a pseudo input signal from 12 to the television receiver 5. The switch 12 is switched to the contact X side when a high level signal comes from the pulse stretch circuit 20 and to the contact Y side when it is low level.

Therefore, the operation will be described with reference to FIG. 2. In the non-scan mode, the frequency dividing circuit 33 is a vertical synchronizing signal separation circuit.
When the vertical sync signal reproduced from the input video signal is detected and output by 15, the pulse is output to the PLL circuit 17 and reset, and then the frequency division is restarted and the pin
The operation of dividing the pulse from 32 by 525 or outputting a pulse again when it is reset is repeated. Therefore, the output pulse of the frequency dividing circuit 33 and the phase of the PLL circuit 17 are synchronized with the phase of the vertical synchronizing signal at the time of normal reproduction.

When the signal of the terminal 19 becomes high level and the scanning operation of the CLV disc is instructed, the pickup 3 is moved in the disc radial direction, and the tracking servo loop is intermittently closed to obtain the signal in the tracking rose period. The video signal is output. Switch at this time
12 is connected to the contact X side, and the switch 31 is open.

When the switch 31 is opened, the frequency dividing circuit 33 only divides the frequency of the signal from the terminal 32 and outputs it, and thereafter it is not reset by the vertical synchronizing signal. Specifically, a carry pulse is supplied to the PLL circuit 17 every time 525 counts of a reference clock having a frequency (= 2f _H ) twice as high as the horizontal synchronizing signal. Since this carry pulse holds the phase of the reproduction sync signal immediately before the start of the scan operation,
The pseudo vertical sync signal output from the mono multivibrator 18 holds the phase of the reproduction sync signal immediately before the start of the scan operation.

As a result, the phase of the vertical synchronizing signal at the time of normal reproduction before the start of the scan operation is maintained as it is during the scan operation (sections A to H in FIG. 2), so that the reproduced image obtained during the scan operation is vertical. It will not flow or be disturbed in any direction.

Then, when the scanning operation is stopped, the switch 31 is closed again, and the frequency dividing circuit 33 operates again from that time point so as to be synchronized with the vertical synchronizing signal (section I in FIG. 2).

The screen of the television receiver 5 during the above operation is as shown in FIG. That is, for section A, section B,
In F, the reproduced vertical synchronization signal itself has no phase difference, so that a normal image can be viewed, and in sections D and H, there is a phase difference, so a vertical blanking period appears in the middle of the screen. The position where this vertical blanking period appears does not change in each section D and H. This is because, in this embodiment, the vertical deflection scanning during the scanning operation is eventually performed by the signal from the fixed oscillator. Therefore, the respective images displayed during the period in which the tracking servo in the scan mode is on do not flow vertically, and the display is very easy to see.

On the other hand, after the scanning operation is completed, the pseudo sync signal is
Due to the flywheel effect of, the phase is gradually synchronized with the reproduction synchronization signal. Also pulse stretch circuit 20
In consideration of the time required for the phase of the PLL circuit 17 to match the phase of the vertical synchronizing signal of the input signal, the switch 12 remains connected to the contact X side for a while even after the end of the scanning operation ( 2 (d)), the contact of the switch 12 is Y
When the switch 12 is switched to the side, the phases of the vertical synchronizing signals output from the contact Y and the contact X are in agreement, so that the screen is not disturbed when the switch 12 is switched, and a very natural feeling is obtained. The image can be displayed on the screen of the television receiver 5 with.

〔effect〕

As described above, in the present invention, since the pseudo sync signal is added to the input signal from which the sync signal is extracted, if the pseudo sync signal is used during the scan operation, the scan operation can be performed even on the CLV disk and at the time of the scan operation. The screen never flows. Further, when the scan operation shifts to the normal operation, the pseudo sync signal is switched after the phase of the reproduced sync signal sufficiently matches the phase of the reproduced sync signal, so that the screen is not disturbed when the sync signal is switched.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment, FIG. 2 is its timing chart, FIG. 3 is a diagram showing how the screen changes, FIG. 4 is a block diagram of a conventional video disc, and FIG. 5 is its operation. FIG. 6 is a diagram showing how the vertical synchronizing signal changes. 1 …… Disk 2 …… Motor 3 …… Pickup 4 …… Demodulation circuit 5 …… TV receiver 10 …… Adapter 11 …… Input terminals 12, 31 …… Switch 13 …… Vertical sync signal extraction circuit 14 …… Phase detector 15 …… Vertical sync signal separation circuit 16 …… Additional circuit 17 …… PLL circuit 18 …… Mono multivibrator 19, 21, 32 …… Terminal 20 …… Pulse stretch circuit

Claims (2)

[Claims] 1. A synchronization signal extracting means for extracting a reproduction vertical synchronization signal from an input signal, and a pulse which is phase-synchronized with the reproduction vertical synchronization signal during non-scanning operation is generated and output based on a scan command pulse from the outside. In the scan operation, a pulse generator that generates and outputs a pulse that is phase-synchronized with the reproduction vertical synchronization signal extracted immediately before the start of the scan operation, and a PLL circuit that receives the output of the pulse generator, Pseudo-sync signal generating means for generating and outputting a pseudo-vertical sync signal phase-synchronized with the pulse; adding means for adding the pseudo-vertical sync signal to the input signal from which the reproduced vertical sync signal has been extracted and outputting the signal. Based on the output of the pulse stretch means for stretching and outputting the pulse width of the scan command pulse, In addition, the output signal of the adding means is selectively output during the period from the start of the scan operation until the time corresponding to the expanded pulse width of the scan command pulse elapses, and the input signal is changed during the other period. A disk scanning device comprising: a selection unit that selectively outputs. 2. The pulse generating means includes a fixed oscillator that generates and outputs a reference signal having a constant frequency, and a frequency dividing counter that frequency-divides the reference signal. The disk scanning device according to claim 1, wherein the disk scanning device is reset by the reproduction vertical synchronizing signal during a non-scan operation.