JPS63152079A - Searching method for disk reproducing device - Google Patents

Abstract

PURPOSE:To prevent a noise picture from being regenerated, by reading repeatedly and outputting video information stored in a video memory during a search operation between a CD (compact disk) area and a video area. CONSTITUTION:When it is decided that a vertical synchronizing signal is outputted from a separation circuit 12 during the regeneration of the video area, a write enable signal (w) for a memory control circuit 19 is started to be sent. Following that, when the vertical synchronizing signal is outputted again, the sending of the write enable signal (w) is stopped. Thus, the video information of one field just before searching is stored in a video memory 18. Next, a CPU starts the search operation to move the information detecting light spot of a designated pickup 3, and when a search destination is a different area, that is the CD area which is a first area made into a PCM (Pulse Code Modulation) and stored, the regeneration of a still picture is performed by switching a selection switch 15 to a (b) side, and reading out repeatedly the video information.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a search method in a disc playback device.

BACKGROUND ART A small digital audio disk with a diameter of about 12 cm called a compact disk (CD) is known as an information recording disk (hereinafter simply referred to as a disk) on which digital signals are recorded. , recently, PCM (Pulse
In addition to the Code Modulation) signal, FM
Discs (hereinafter referred to as composite discs) on which a modulated video signal and a PCM signal are recorded in a superimposed manner are being developed.

In this composite disc, as shown in FIG.
Information is recorded in a second area (hereinafter referred to as video area) 1b in which a modulated video signal and a PCM audio signal are recorded in a superimposed manner. The video signal contains higher frequency components than the PCM signal, and the frequency spectrum of the signal recorded in the video area 1b is as shown in FIG. In the figure, the component indicated by A is a PCM signal, and the component indicated by B is a video FM signal. Therefore, when recording signals to the video area 1b, it is necessary to increase the rotational speed of the disc compared to when recording to the CD area 1a, and as a result, as a matter of course, during playback, the rotational speed of the disc must be higher than that when recording signals to the CD area 1a. The disc must be played back at a high rotational speed in the video area 1b. As shown in FIG. 5, the rotation speed is several hundred rpm in the CD region 1a, whereas
In the video area 1b, the speed is around 2,000 rpm at the innermost circumference of the area,
The rotational speed is extremely high, reaching over 1,000 rpm at the outermost circumference.

When playing such a composite disc, the video area and C
When performing a search operation with area D, the disk rotational speeds in both areas are extremely different, so it takes time to stabilize at the rotational speed of the search destination, and the search speed is slower than when searching in the same area. It will take time. Therefore, during a search operation between the video area and the CD area, video information is not input to the TV monitor for a long time, which may cause noise on the TV monitor screen, impairing visibility. there is a possibility.

Summary of the Invention The present invention has been made in view of the above-mentioned points, and an object of the present invention is to provide a search method that can display an image on a television monitor even during a search operation between a video area and a CD area. shall be.

The search method according to the present invention stores last read video information in the video memory when playing a video area in a disc playback device having a video memory, and stores the last read video information in the video memory.
It is characterized in that during a search operation between the D area and the video area, video information stored in the video memory is repeatedly read out and output as playback information.

Example Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

FIG. 1 is a block diagram showing an example of a disc playback device to which a search method according to the present invention is applied.

In the figure, a disk 1 is rotationally driven by a spindle motor 2, and recorded information is read by an optical pickup 3. The pickup 3 includes an optical system including a laser diode, an objective lens, a photodetector, etc., and a focus actuator that drives the objective lens in the optical axis direction with respect to the information recording surface of the disk 1. A tracking actuator and the like are built in to bias the beam spot (information detection point) in the disk radial direction with respect to the recording track. The pickup 3 is mounted on a slider 4 that is movable in the radial direction of the disk, and the slider 4 is linearly driven by a transmission mechanism 6 that uses a slider motor 5 as a drive source and is made up of a combination of a rack and pinion, for example.

A read RF (high frequency) signal output from the pickup 3 is supplied to a video information demodulation system 8 and a digital information demodulation system 9 via an RF amplifier 7.

In the video information demodulation system 8, the RF from the RF amplifier 7
The signal is demodulated into a video signal by a double signal demodulation circuit 10, and then supplied to a time base correction circuit 11 and a separation circuit 12. The separation circuit 12 separates and extracts a horizontal (H) synchronization signal, a vertical (V) synchronization signal, and control data contained in the video signal. The time axis correction circuit 11 includes, for example, a CCD (Cha
It is configured to perform time axis correction by changing the amount of delay of the element in accordance with a control signal from the time axis control circuit 13. The time axis control circuit 13 is
For example, the oscillation output of a crystal oscillator (VCXO) 14 that oscillates in synchronization with a horizontal synchronization signal and its frequency-divided output separated and extracted by the separation circuit 14, and the horizontal synchronization signal and color in the video signal that have passed through the time axis correction circuit 11. It is configured to output a control signal according to the phase difference with the burst signal, and its specific configuration is shown in Japanese Patent Application Laid-Open No. 56-102182.

The time axis corrected video signal is supplied to a selection switch 15 and is also supplied to an A/D (analog/digital) converter 17 via an LPF (low pass filter) 16. In the A/D converter 17, the video signal is sampled at a predetermined period, and the obtained sample values are sequentially converted into digital data. The output data of this A/D converter 17 is supplied to a video memory 18 consisting of a RAM (random access memory) or the like.

As the video memory 18, one having a storage capacity capable of storing at least one field of video information is used. Address control and mode control of the video memory 18 are performed by a memory control circuit 19. One memory control circuit sequentially reads out data written in each address of the video memory 18 using a clock from a reference clock generation circuit 20, and reads out data written in each address of the video memory 18 in response to a write enable signal W output from a system controller 21, which will be described later. The configuration is such that control is performed to rewrite the contents of each address in the memory 18.

The data read from the video memory 18 is
The signal is converted into an analog signal by the (digital/analog) converter 22, and becomes the external power of the selection switch 15 via the LPF 2B. The selection switch 15 is normally located on the a side and supplies the video signal directly supplied from the time axis correction circuit 11 to the video output terminal 24, and is switched to the b side in response to a switching command from the system controller 21 to output the video memory. 18 is selected and supplied to a video output terminal 24.

On the other hand, the digital information demodulation system 9 is provided with a selection switch 25 that switches depending on the area to be played (CD area and video area) when playing a composite disc.
This switch 25 is located on the a side when reproducing the CD area, and on the b side when reproducing the video area, and the switching is performed in response to a switching command issued from the system controller 21.

In the case of a composite disc, as explained in FIG.
The rotational speed of the disc is extremely different between the area and the video area, and the PCM audio signal is, for example, EFM
(Eight to Fourteen Modula
In the video domain, if the digital signal is directly superimposed on the FM modulated video signal during recording, the EFM signal will have a negative effect on the low-frequency components of the FMM video signal, so the modulation degree is are equivalent, but the EFM signal is recorded in a state where the signal level is suppressed by several tens of outputs with respect to the video carrier (see FIG. 4). Therefore, even if the EFM signal is the same, the frequency characteristics and amplitude will be different when playing back the CD area and when playing the video area.
By switching the signal processing system, the demodulation system can be shared.

That is, when reproducing the CD area, the reproduced RF signal is EF
The E F M signal has its frequency characteristics compensated by an equalizer circuit 26 having predetermined equalizing characteristics, and is further amplified by an amplifier 27 with a predetermined gain.

On the other hand, in the case of video area playback, only the EFM signal included in the playback RF signal together with the FM video signal is
The frequency characteristics are extracted by an EFM extracting circuit 28 consisting of a PF, etc., and the frequency characteristics are compensated by an equalizer circuit 29 having equalizing characteristics different from those of the equalizer circuit 26.
By being amplified by the amplifier 30 having a gain greater than 7, the EFM signal is output as an EFM signal with frequency characteristics and amplitude equivalent to those during CD region reproduction.

Incidentally, when playing back a compact disc, the selection switch 25 is always in the state where the a side is selected.

The reproduced EFM signal selected by the selection switch 25 is demodulated and
The signal is supplied to the correction circuit 31. This demodulation/correction circuit 31 demodulates the EFM signal and writes it into a memory such as a RAM, controls the RAM based on the clock from the reference clock generator 32, exchanges data, and performs deinterleaving and the data. Error correction is performed using the parity contained in the data, and control data is further detected. The digital audio signal demodulated and corrected by the demodulation/correction circuit 31 is processed by an audio signal processing circuit 33 consisting of a D/A converter, a deglitcher circuit, etc., and then supplied to left and right channel audio output terminals 34L and 34R. be done.

A detection signal is generated near the travel path of the pickup 3 in the disk radial direction by detecting that the beam spot emitted from the pickup 3 has arrived at a position corresponding to the vicinity of the boundary between the CD area and the video area on the composite disk. A position detector 35 is provided. By generating this detection signal, it is possible to detect that the pickup 3 has reached the video area. As the position detector 35, one having a well-known configuration such as an optical sensor can be used. A detection signal output from the position detector 35 is supplied to the system controller 21.

The system controller 21 is composed of a microcomputer including a CPU (central processing circuit), ROM (read only memory), RAM, and the like.

This system controller 21 receives the horizontal synchronization signal, vertical synchronization signal and control data from the separation circuit 12, as well as demodulation and control data.
Control data from the correction circuit 31, disc designation information indicating whether the disc to be played back is a compact disc or a composite disc from the operation unit 36, whether the playback area when playing a composite disc is only a CD area or only a video area, or Mode designation information indicating whether it is a double-headed area or the like is supplied. In this system controller 21, the CPU processes signals input manually according to a program stored in advance in the ROM,
It controls various parts such as the selection switches 15 and 25, the memory control circuit 19, a drive circuit (not shown) for driving the spindle motor 2, a drive circuit 37 for driving the slider motor, and a display section 38.

Next, the procedure of the search method according to the present invention executed by the CPU constituting the system controller 21 in the disc playback device having such a configuration will be explained according to the flowchart of FIG. 2.

When a key operation is performed by the user during execution of the main routine or a subroutine for controlling play operations, it is determined whether a search (address search) command has been issued (step Sl). When it is determined that no search command has been issued, the routine returns to the routine that was being executed immediately before proceeding to step S1, and the execution of that routine is resumed. When it is determined in step S1 that a search command has been issued, it is then determined whether a video area is being reproduced (step S2).

When it is determined in step S2 that the video area is being played back, the vertical (V) synchronization signal is then sent to the separation circuit 12.
(Step S3)
. If the vertical synchronization signal is not output, step S3
When it is determined that the vertical synchronization signal has been output, the CPU 11 starts sending out the write enable signal W to the memory control circuit 19 (step S4). Then again,
It is determined whether or not the vertical synchronization signal is outputted from the separation circuit 12 (step S5). If it is determined that the vertical synchronization signal is not outputted, the execution of step S5 is repeated; Sending out the write enable signal W is stopped (step S6). As a result, video information for one field immediately before the search is stored in the video memory 18.

Next, the CPU starts a search operation to move the information detection optical spot of the pickup 3 to the address specified by the search command (step S7), and then determines whether the search destination is a different area (step S8). When it is determined that the search destination is a different area, that is, the CD area, the selection switch 15 is switched to the b side and the video memory 18
The still image is reproduced by repeatedly reading out the video information stored in the still image (step S9).

Next, it is determined whether the search operation is completed and the information detection light spot has reached the designated address (step 510), and step S9 is repeated until it is determined that the information detection light spot has arrived. Step S1 at the time
Return to the routine that was running immediately before transitioning to , and resume execution of that routine. When it is determined in step S8 that the search destination is the same area, that is, a video area, the still image is not reproduced and the process directly proceeds to step SIO.

Furthermore, after the search operation from the video area to the CD area is completed, playback of the CD area is started, but since video information cannot be obtained in the CD area, the playback period selection switch 15 of the CD area is set to the b side. It is also possible to continue playing still images based on the video information stored in the video memory 18 by switching.

On the other hand, when it is determined in step S2 that the CD area is being played, the process moves to step S7 to start a search operation, and when it is determined in step S8 that the search destination is a different area, that is, a video area, If the video area has been played by then, the last read video information will be stored in the video memory 18 for one field unless the disc is ejected, so the still image can be played back by repeatedly reading out the video information. (Step S9). Note that if the video area has not been played by then, video memory 1
Since no video information is stored in 8, still images cannot be played back.

However, by storing, for example, blue screen information in the video memory 18 during initialization when the system is started up, or by configuring the system to selectively output blue screen information using a character generator, the television monitor can project a blue screen.

By the above operation, even during a search operation between the video area and the CD area, that is, between different areas, the video information previously stored in the video memory 18 can be displayed on the television monitor.

As described in detail, according to the search method according to the present invention,
The last read video information when playing the video area is stored in the video memory, and the video information stored in the video memory is repeatedly read out during a search operation between the CD area and the video area and output as playback information. By doing so, it is possible to display an image on the television monitor even during a search operation between both areas, so that it is possible to prevent the reproduction of a noise screen.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an example of a disc playback device to which the search method according to the present invention is applied, FIG. 2 is a flowchart showing the procedure of the search method according to the present invention executed by a CPU, and FIG. FIG. 4 is a diagram showing the frequency spectrum of a signal recorded in the video area of the composite disc, and FIG. 5 is a diagram showing the division of the information recording area on the composite disc. Explanation of symbols of main parts 1...Disk 2...Spindle motor 3...Optical pickup 5...Slider motor 8...Video Information demodulation system 9... Audio information demodulation system 11... Time axis correction circuit 15.25... Selection switch 18... Video memory

Claims (1)

[Claims] A disc reproducing device capable of reproducing an information recording disc having a first area in which only a predetermined digital signal is recorded and a second area in which a frequency modulated video signal and a predetermined digital signal are recorded in a superimposed manner. In the search method, the disc playback device has a video memory capable of storing at least one field of video information, and the last read video information during playback of the second area is stored in the video memory. A disc characterized in that the video information stored in the video memory is repeatedly read out during a search operation between the first area and the second area and output as playback information. Search method in playback device.