JPS6177481A - Disk scanner - Google Patents

Abstract

PURPOSE:To attain a scanning action on a CLV disk by detecting the phase of a reproduction synchronizing signal before a device shifts to the scanning action and holding the phase as much as possible at the time of the scanning action. CONSTITUTION:When a reproduction vertical synchronizing signal is detected and outputted from a vertical synchronous separator circuit 15 at the time of non-scan, a frequency divider circuit 33 outputs a pulse to a PLL circuit 17, and simultaneously is reset. Afterward, the action that the circuit 33 restarts the frequency division to carry out the 525-frequency division of the pulse from a terminal 21, or the action that the circuit 33 outputs the pulse as it is set is repeated. When the signal of a terminal 19 comes to a high level and the scanning action of a CLV disk is indicated, a switch 31 becomes opened. Accordingly the circuit 33 simply divides and outputs the frequency of the signal from the terminal 32, and afterward it will never be reset with the aid of the reproduction vertical synchronizing signal. As a result, the phase of the reproduction synchronizing signal before the start of the scanning action can be held as it is during the scanning action.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention scans desired recorded information by moving a pickup in the radial direction of an information recording medium such as a video disk at a speed higher than the normal playback speed. The present invention relates to a device that performs a so-called visual scan operation.

[Conventional technology]

For example, video discs are played back using a configuration as shown in FIG. In the figure, reference numeral 1 denotes a disk which is rotated by a remote control 2. As shown in FIG.

A pickup 3 irradiates the disc 1 with laser light or the like to reproduce recorded information. The reproduced RF signal obtained from the pickup 3 is demodulated by a demodulation circuit 4 and supplied to a television receiver 5 as a video signal.

In normal playback operation, the tracking servo loop of the pickup 3 is closed, so the pickup 3 is transported in the radial direction of the disk at a relatively slow speed.

A good video signal can be obtained. However, during a visual scan operation such as when searching for a desired screen while watching a television receiver.

The pickup 3 is transported in the disk radial direction at a relatively high speed. At this time, the tracking servo loop of the pickup 3 is closed in a certain section and opened in a certain section, and this operation is repeated. When the tracking servo loop is closed, the pickup 3 can follow the track on the disk 1, so a good video signal can be obtained. However, when the tracking servo loop is open, the pickup 3 crosses (jumps over) the track, resulting in a poor video signal containing noise. FIG. 7 schematically represents these matters. Sections A and 2 are playback modes, and sections B to H are scan modes.

Section C (E, G) is a section that occurs to return the tracking mirror (not shown) of pickup 3 to its original position when it has rotated to its rotation limit, and usually corresponds to several hundred tracks. , which is extremely short in terms of time.

[Problem that the invention seeks to solve]

By the way, during such a scan operation, there is no problem in the case of a CAV disk, but in the case of a CLV disk, the phase of the vertical and horizontal synchronization signals extracted from the playback signal will be shifted. Since information is recorded to be constant, each synchronization signal is aligned on a radial line on the disk, whereas C
This is because information is recorded on the LV disc so that the linear velocity is constant, so the synchronization signals are not aligned on the radial line on the disc. In the case of CL and V disks, theoretically sections B and D (D and F, F and H
), the phase changes randomly within the range of ±π. As shown in Fig. 8, the vertical synchronization signal that continuously arrives at a predetermined period in the case of a CAV disk does not arrive at a predetermined period in the case of a CLV disk, but before and after sections B and D. This means that it is discontinuous (because the periods C, E, and G are short, they are almost ignored in FIG. 8). Therefore, when a CL disk is scanned, the vertical deflection scan is disturbed and the screen moves in the vertical direction, resulting in an extremely unsightly image, making it virtually impossible to scan a CLV disk with conventional devices6. Means for Solving the Problems] The present invention can be 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, 11 is an input terminal into which a demodulated video signal is input, and a contact Y of a switch 12 and a vertical synchronization signal extraction circuit 13 that extracts a vertical synchronization signal from the input signal.
and a vertical synchronization signal separation circuit 15 constituting a phase detection means 14 for detecting the phase of the vertical synchronization signal of the input signal.

The signal from which the vertical synchronizing signal has been extracted through the vertical synchronizing signal extracting circuit 13 is added with a pseudo vertical synchronizing signal by an additional circuit 16, and then output to the contact X of the switch 12. 17 is a PLL constituting the phase detection means 14
This circuit outputs a signal with a phase corresponding to the signal from the vertical synchronization signal separation circuit 15. A mono multivibrator 18 serves as a pseudo vertical synchronizing signal generating means, and supplies the additional circuit 18 with a pseudo vertical synchronizing signal of 3H (H is the period of the horizontal synchronizing signal) corresponding to the vertical synchronizing signal of the input signal. Reference numeral 19 denotes a terminal, to which a high-level signal is supplied when the CLV disk is scanned, and a low-level signal is supplied when the CLV disk is not scanned, from a microcomputer or the like (not shown). 20 is a pulse stretch circuit 6 that delays only the falling edge of the pulse signal from the terminal 19.
21 transfers the signal from the switch 12 to the television receiver 5
This is the output terminal that supplies the The switch 12 is switched to the contact X side when a high level signal is received from the pulse stretch circuit 20, and to the contact Y side when the signal is low level.

[Effect]

However, to explain its operation, 1. When a normal playback operation is being performed, a low level signal is supplied from terminal 19, so switch 12 is switched to the contact Y side, and the signal input to terminal 11 is The signal is output to the terminal 21 as it is.

When a high level signal is input from terminal 19 and a CLV disk scan operation is instructed.

The switch 12 is switched to the contact X side. Also at that time, the PLL@path 17 has its time constant switched from a small value to a large value (switched from wideband operation to narrowband operation).

On the other hand, the vertical synchronizing signal is extracted from the input signal input to the terminal 11 by the vertical synchronizing signal extracting circuit 13, and the vertical synchronizing signal is extracted from the input signal to the additional circuit 11.
A vertical synchronizing signal is separated from the input signal 6 by a vertical synchronizing signal separation circuit 15 and is supplied to a PLL circuit 17 . Therefore, the PLL circuit 17 outputs a signal synchronized with the phase of the reproduced vertical synchronization signal. As a result, the mono multivibrator 18 outputs a pseudo vertical synchronization signal to the additional circuit 16 in synchronization with the phase of the reproduced vertical synchronization signal. The addition circuit 16 adds a pseudo vertical synchronization signal to the signal from which the vertical synchronization signal has been extracted and outputs the signal.

Assuming that the scan operation changes the phase of the reproduced vertical synchronizing signal as shown in FIG. 2(a), the phase of the output signal of the PLL circuit 17 changes as shown in FIG. 2(b). In other words, the PLL circuit 17 has a so-called flywheel effect, and since the time constant is switched to a larger one, the effect is even greater, so even if there is a sudden phase change, it will be quickly canceled. Instead of following it, they try to maintain the state before the change. As a result, the phase change becomes slow, and the vertical deflection scanning of the television receiver 5 can follow the change, making it possible to perform a scanning operation on the CLV disc.

When the level of the signal at the terminal 19 becomes low and the scanning operation is stopped (FIG. 2(c)), the PLL circuit 17 is switched from the one with a larger time constant to the one with a smaller time constant (switching from narrowband operation to wideband operation). ). As a result, PL
The time required for phase synchronization of the L circuit 17 is shortened, and the vertical shift of the screen after the scan operation is completed is quickly eliminated.

In addition, in consideration of the time required for the phase of this PLL circuit 17 to match the phase of the vertical synchronization signal of the input signal, the switch 12 is connected to the contact X side for a while even after the pulse stretch circuit 20 finishes the scan operation. I will leave it as is (
2(d)), when the contact of the switch 12 is switched to the Y side, the phases of the vertical synchronization signals output from the contact Y and the contact X match, so the switch 12 switches The screen will not be distorted when

〔Example〕

FIG. 3 represents another embodiment of the invention. In the figure, parts corresponding to those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted.

In this embodiment, the phase detection means 14 is composed of a vertical synchronizing signal separation circuit 15 and a PLL circuit 17, as well as a switch 31 and a frequency dividing circuit 33 to which a signal from a fixed oscillator is supplied from a terminal 32. There is. For example, a signal with a frequency twice the frequency fl of the horizontal synchronizing signal is supplied to the terminal 32, and this signal is converted to 11525 by the frequency dividing circuit 33.
Therefore, the frequency dividing circuit 33 outputs a signal having the same frequency as the vertical synchronizing signal to the PLL circuit ]-7. The switch 31 is open when a high level signal is output from the terminal 19 and closed when the signal is low level. The signal from the vertical synchronization signal separation circuit 15 is supplied to the reset terminal of the frequency dividing circuit 33. It looks like this.

The operation will be explained with reference to FIG. 4. During non-scanning, the frequency divider circuit 33 outputs the PL signal when the reproduced vertical synchronization signal is detected and output from the vertical synchronization signal separation circuit 15.
It is reset while outputting a pulse to the L circuit 17,
From that point on, frequency division is restarted, and the operation of dividing the pulse from the terminal 32 by 525 and outputting another pulse when set is repeated. Therefore, frequency divider circuit 3
The output pulse of No. 3 and the phase of the PLL circuit 17 are synchronized with the phase of the reproduced vertical synchronization signal.

When the signal at the terminal J9 becomes high level and a CLV disk scanning operation is instructed, the switch 31 becomes an oven. Therefore, the frequency dividing circuit 33 only divides the frequency of the signal from the terminal 32 and outputs it, and is no longer reset by the reproduced vertical synchronizing signal. As a result, the phase of the reproduced vertical synchronization signal immediately before the start of the scan operation is maintained during the scan operation (sections A to H in FIG. 4).

Then, when the scan operation is stopped, the switch 31 is closed again, and the 1 frequency divider circuit 33 operates again from that point on in synchronization with the reproduced vertical synchronizing signal (section operation in Fig. 4). This is the same as in the figure.

The screen of the television receiver 5 during the above operation is as shown in FIG. In other words, for section A, section B
In , F, there is no phase difference in the reproduced vertical synchronization signal itself, so a normal image can be viewed.In H, there is a phase difference, so a vertical blanking period appears in the middle of the screen. The position where the vertical blanking period appears does not change in each interval. This is because, in this embodiment, vertical deflection scanning during the scanning operation is ultimately performed by a signal from a fixed oscillator. Therefore, in the case shown in FIG. 1, the position at which this vertical blanking period appears changes in each section and H, and the position flows from top to bottom or from bottom to top. In section (3), a vertical blanking period initially appears until the phase of the PLL circuit 17 matches the phase of the reproduced vertical synchronizing signal, but once they match, it no longer appears. Thereafter, the same operation will be repeated using the phase of the reproduced vertical synchronization signal in section I as a reference.

〔effect〕

As described above, in the present invention, the phase of the reproduction synchronization signal is detected before shifting to the scan operation.

Since the phase is maintained as much as possible during the scan operation, and the phase change is made slow or almost eliminated, and the deflection scan is performed using the synchronization signal, the scan operation is possible even on a CLV disk.

[Brief explanation of drawings]

Figure 1 is a block diagram of the adapter of the present invention, Figure 2 is its timing chart, Figure 3 is a block diagram of another embodiment, Figure 4 is its timing chart, and Figure 5 is how the screen changes. 6 is a block diagram of a conventional video disk, FIG. 7 is an explanatory diagram of its operation, and FIG. 8 is a diagram illustrating how its vertical synchronizing signal changes. 1...Disc 2...Motor 3...Pickup 4...Demodulation circuit 5...Television receiver 10...Adapter 11...Input terminal 12.31
...Switch 13...Vertical synchronization signal sampling circuit 14...Phase detection means 15...Vertical synchronization signal separation circuit 16...Additional circuit 17...PLL circuit 18...
・Mono multivibrator 19.21.32...terminal 20...pulse stretch circuit 33...branch circuit or higher

Claims (5)

[Claims] (1) Synchronization signal extracting means for extracting a synchronization signal from an input signal; pseudo synchronization signal generation means for generating a pseudo synchronization signal corresponding to the synchronization signal of the input signal; Additional means for adding a pseudo synchronization signal; and phase detection means for detecting the phase of the synchronization signal of the input signal; when the phase of the synchronization signal of the input signal changes during a scan operation, the phase detection means The means maintains the phase of the synchronizing signal before changing, the pseudo synchronizing signal generating means is operated by the signal of the maintained phase, and the pseudo synchronizing signal generated is extracted by the adding means. What is claimed is: 1. A disc scanning device characterized in that the input signal is added to the received input signal. (2) The phase phase detection means includes a PLL circuit, and the PLL circuit
2. The disk scanning device according to claim 1, wherein said signal having a maintained phase is generated by utilizing a flywheel effect of an L circuit. (3) The phase detection means has a frequency division means for frequency dividing the signal from the fixed oscillator, and before the scanning operation, resets the frequency division means with the phase of the synchronization signal of the input signal to generate the synchronization signal. 3. The disk scanning device according to claim 1, wherein the synchronization signal is synchronized with the phase of the input signal, and synchronization with the synchronization signal of the input signal is stopped during the scan operation. (4) The disk scanning device has a switch that selectively outputs either the signal to which the pseudo sync signal is added or the input signal, and during the scan operation, the pseudo sync signal is added to the switch. 4. A disc scanning device according to claim 1, 2, or 3, wherein the disc scanning device selectively outputs the input signal and the input signal during normal playback operation. (5) When the switch shifts from the scanning operation to the reproducing operation, at least the time required for the phase of the output of the phase detection means to substantially match the phase of the synchronization signal of the input signal, and the pseudo synchronization signal 5. The disk scanning device according to claim 4, wherein the disk scanning device outputs a signal to which is added.