JPS63125064A - Scanning system in information reproducing device - Google Patents

Abstract

PURPOSE:To reduce the burden of a tracking actuator by starting a track jump moving action just after rewriting the stored contents in a video memory with at least one field of video information. CONSTITUTION:When a scan command is issued, a video signals written in a RAM 33 are selectively outputted from a switching switch 30 and a forced feed command signal (b) is transmitted so as to drive a slider 9 by force. When a tracking open command signal (a) is outputted, a light spot for detecting information moves with jumping the tracks of a disk 2. After that, when a write is completed the signal (a) is outputted again so as to start the track jump moving action of the light spot for information detection. Thus, the time for continuing playing actions is shortened and the deviation quantity of the tracking actuator is made small, so that the burden of the actuactor is reduced and the fault can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a scan type recording disk in an information reproducing apparatus, a CAM (constant angular velocity) disk and a CLV (
(constant linear velocity) disk exists.

In the case of a CAM disk, a certain group of information, for example, video information for one frame, is recorded on one round of tracks formed at any position in the radial direction, and a track located at the boundary between each frame is recorded. The portions in which information corresponding to the vertical synchronization signal is recorded exist so as to be arranged on a straight line extending in the radial direction. Therefore, in the CAM disk, there is no disturbance in the period of the synchronization signal of the reproduced video signal immediately after the jump operation, and special reproduction such as still image reproduction can be performed satisfactorily.

However, in the case of a CLV disc, the amount of information recorded on one track varies depending on the position in the radial direction. For example, the innermost track contains video information for one frame, and the outermost track For example, video information for three frames is recorded on the track. For this reason, in the CLV disk, a disturbance occurs in the period of the synchronization signal of the video signal obtained immediately after the jump operation. Therefore, a video memory with a storage capacity ω capable of storing one frame or one field of video signals is provided, the video signal is converted into a digital signal by a clock synchronized with the reproduced video signal, and this is stored at a predetermined location in the video memory. Information reproducing apparatuses have been proposed in which information is read out using an external stabilizer or an external device.

In such an information reproducing apparatus, it is possible to perform high-speed reproduction by so-called scanning, which alternately performs a track jumping operation (jump operation) of the information detection point of the pickup and a play operation. At this time, the slider servo that controls the position of the slider carrying the pickup in the radial direction of the recording disk is turned off to forcibly move the slider, and at the same time, the tracking servo loop is opened at predetermined time intervals to move the slider over tracks. It is possible to perform an action. In this case, the amount of deflection of the tracking actuator built into the pickup gradually increases, and when the tracking servo loop opens, the tracking actuator returns to the midpoint of its movable range. By the operation of this tracking actuator, the information detection point moves across the track. By rewriting the stored contents of the video memory in synchronization with this track-jumping movement, high-speed reproduction without image disturbance caused by track-jumping movement can be performed.

However, in such conventional scanning methods, when the tracking servo loop is closed and the play operation is performed, it is necessary to continue the play operation for a long time (about 33 ms) in order to reliably obtain one field's worth of video information. , the deviation of the tracking actuator becomes large and the load on the tracking actuator increases,
There was a fear that failures would be more likely to occur. In addition, when the tracking 1 servo loop opens, the number of tracks that the pickup information detection point jumps through becomes large, so the difference in frequency between the video signals obtained immediately before and after the servo loop opens becomes large, and the time base servo ( This also places a heavy burden on the time axis servo.

For this reason, especially in a disk with a large eccentricity, the time axis error exceeds the control range of the COD for removing the time axis error, resulting in color disturbance.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a scanning method that can reduce the burden on a tracking actuator and at the same time obtain an image without color disturbance.

In the scanning method according to the present invention, at least one field worth of video information of information obtained from a recording disk is stored in a video memory during a play operation that is performed alternately with a track jumping operation in response to the scanning method. The feature is that the track jumping operation is started immediately after the content is rewritten.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In FIG. 1, recorded information on a disk 2 that is rotationally driven by a spindle motor 1 is read by an optical pickup 3. As shown in FIG. The pickup 3 includes a laser diode, an objective lens, a focus actuator, a tracking actuator, a photodetector, and the like. The output of the pickup 3 is supplied to the RF amplifier 4 and, at the same time, to a focus servo circuit (not shown) and a tracking servo circuit 52. These focus servo circuits and tracking servo circuits drive the focus actuator and tracking actuator in the pickup 3, and the laser light emitted from the laser diode in the pickup 3 is directed to the disk 2.
in the radial direction of the disk 2 so that a light spot for information detection (information detection point) is converged on the recording surface of the disk 2, and this light spot is located on a track formed on the recording surface of the disk 2. The position of the light spot is controlled. The tracking servo circuit 52 is configured to open the tracking servo loop in response to the tracking open command signal a and stop position control of the information detection light spot.

Further, the coil current supplied to the coil for driving the tracking actuator in the pickup 3 is supplied to the current detection circuit 5. A current detection signal corresponding to the coil current is output from the 7Ii current ratio detection 5 and supplied to the slider servo circuit 6. In the slider servo circuit 6, the current detection signal is amplified and phase compensated.

The output of this slider servo circuit 6 is the motor drive circuit 7
becomes a drive signal for the slider motor 8. This slider motor 8 drives a slider 9 on which the pickup 3 is mounted and is movable in the disk radial direction, and the tracking actuator in the pickup 3 is controlled so as to be located at the midpoint of its movable range. Note that the slider servo circuit 6 controls the slider 6 by the forced feed command signal.
is configured to forcibly move in the radial direction of the disk 2.

On the other hand, the RF multiplied signal output from the RF amplifier 4, BPF
(Bandpass filters) 10 and 11 are supplied to extract and separate the left and right channel audio FM signals. These two channels of audio FM signals are supplied to FM demodulators 12 and 13, respectively, to reproduce the two channels of audio signals. The audio signals of these two channels are processed by the de-emphasis circuit 1
4 and 15, and the components emphasized during recording are returned to their original levels. Audio signals output from these de-emphasis circuits 14 and 15 are supplied to audio output terminals 16 and 17.

In addition, the RF multiplied signal output from the RF amplifier 4, BPF
18, and the video FM signal is extracted and separated. After the amplitude of this video FM signal is limited by a limiter 19, it is supplied to an FM demodulator 20 to reproduce the video signal. This video signal is supplied via an LPF (low pass filter) 21 to one input terminal of a changeover switch 22 for dropout compensation. Changeover switch 2
A video signal delayed by an IH (horizontal synchronization period) delay line 23 is supplied to the other input terminal of 2. A dropout detection signal output from a dropout detection circuit 50 is supplied to this changeover switch 22 as a control signal. The dropout detection circuit 50 is supplied with the RF multiplied signal high frequency component extracted and separated by an HPF (bypass filter) 51. The dropout detection circuit 50 is configured to detect a dropout using, for example, a zero-crossing point of the high-frequency component of the RF multiplied signal and generate a dropout detection signal. This dropout detection signal controls the signal switching of the selector switch 22, and when a dropout occurs, the video signal 1H before output from the 1-day delay line 23 is selectively output from the selector switch 22 to compensate for the dropout. It will be done.

The video signal output from the changeover switch 22 is a CCD
(Charae Coupled Device
)24. A clock output from ■C○ (voltage controlled oscillator) 25 is supplied to C0D24. At C0D24, the video signal is delayed by a time depending on the clock frequency. The video signal output from this C0D 24 is supplied to a separation circuit 26. The separation circuit 26 extracts a horizontal synchronization signal, a vertical synchronization signal V, and control data C such as a Phillips code from the video signal.
is configured to separate the The horizontal synchronizing signal output from the separation circuit 26 is supplied to a spindle servo circuit 27. In the spindle servo circuit 27, the horizontal synchronization signal is phase-compared with a reference signal of a predetermined frequency from the reference signal generation circuit 28, and a spindle error signal is generated according to the phase difference between the two signals. This spindle error signal is supplied to the motor drive circuit 29 to control the rotational speed of the spindle motor 1. At the same time, the I
A III1 signal is generated and applied to the control input terminal of VCO 25. Then, the oscillation frequency of the vCO 25 becomes in accordance with the phase difference between the horizontal synchronizing signal and the reference signal, and the signal delay time of the CCE) 24 changes in accordance with the phase difference, thereby eliminating the time axis error.

The video signal whose time axis error has been removed by the C0D 24 is supplied to one input terminal of the changeover switch 30 and at the same time is supplied to the A/D (analog/digital) converter 32 via the LPF 31. In the A/D converter 32, 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 32 is supplied to a RAM 33 as a video memory. Address control and mode control of the RAM 33 are performed by a memory control circuit 34. The memory control circuit 34 sequentially reads the data written in each address of the RAM 33 by the clock from the reference signal generation circuit 28, and rewrites the contents of each address of the RAM 33 in response to the write enable signal W. The configuration is such that it is controlled as desired. RAM3
The data read from the D/A converter 35 is supplied to the D/A converter 35 and converted into an analog signal. This D/A converter 35
The output is sent to the sink insert circuit 3 via the LPF 36.
7, a synchronizing signal is added, and the video signal is reproduced. The video signal output from the sink insert circuit 37 is supplied to the other input terminal of the changeover switch 30.

The changeover switch 30 is supplied with a control signal d for changeover control from the system controller 40 .

One of the video signal that has passed through the RAM 33 from the changeover switch 30 and the video signal that has been directly supplied to the changeover switch 30 from the C0D 24 is selectively supplied to the character insertion circuit 41. The character insertion circuit 41 is configured to combine the video signal corresponding to the character indicated by the data sent from the system controller 40 with the video signal from the changeover switch 30. A video signal output from this character insertion circuit 41 is supplied to a video output terminal 42.

The system controller 40 includes a processor, ROM, R
It is formed by a microcomputer consisting of AM, programmable timer, etc. This system controller 4
0 receives a synchronization signal and control data from the separation circuit 26, data corresponding to key operations on the operation key 48, a loading detection signal from the loading mechanism, a disk detection signal, etc. In the system controller 40, the processor processes input signals according to a program stored in advance in the ROM, and processes the input signals using the slider servo circuit 6, the spindle servo circuit 27, the changeover switch 30, and the memory t.
11 control circuit 34, character insertion circuit 41, drive circuit 43 that drives the laser diode, track jump drive circuit 44 that drives the tracking actuator in response to a jump command, and motor 45 of the disk loading mechanism.
, a motor drive circuit 46, a display circuit 47, a tracking servo circuit 52, and other components. Further, a power supply terminal of the system controller 40 is supplied with power through a diode D. A capacitor C is connected between the power terminal of the system controller 40 and ground. A backup circuit 49 is formed by the diode D and the capacitor C, and power is supplied to the system controller 40 even when the power is off.

In the above configuration, the operation of the processor in the system controller 40 will be explained with reference to the flowchart in FIG. 2.

When a scan command is issued by operating a key on the operating unit 48 during execution of a main routine or the like, the processor proceeds to step S1 and determines whether or not the vertical synchronization signal qv is output from the separation circuit 26. When it is determined in step S1 that the vertical synchronization signal V is not output,
The processor repeatedly executes step S1, and moves to step S2 only when it is determined that the vertical synchronizing signal (3) is being output. In step S2, the processor stops sending out the write enable signal W and
prevent the video signal from being written to 33,
And by controlling the changeover switch 30, the RAM3
3 is selectively supplied to the output terminal 42.

Next, the processor moves to step S3 and starts sending a forced feed command signal S to the slider servo circuit 6. The processor then moves to step S4 and ovens the tracking servo loop for 10m5.

Next, the processor moves to step S5, sets the clock time of the programmable timer in the system controller 40 to 5 ms, and starts the clock operation of this programmable timer. The processor then performs step S
6, it is repeatedly determined whether or not the time counting operation of the 5 ms timer has ended, and only when the 5 ms type time measuring operation has ended, the process moves to step S7.

In step S7, the processor determines whether the vertical synchronization signal V is output from the separation circuit 26. When it is determined in step S7 that the vertical synchronizing signal V is not output, the processor repeatedly executes step S7, and only when it is determined that the vertical synchronizing signal V is being output, the processor moves to step S8. .

In step S8, the processor starts sending out the write enable signal W. Next, BroHizza moves to step S9 and determines whether a scan command is being issued continuously. When it is determined in step S9 that a scan command has been issued, the processor moves to step S10, and the vertical synchronization signal ■ is sent to the separation circuit 2.
6. It is determined whether or not it is output from 6. Step S1
When it is determined that the vertical synchronizing signal (2) is not outputted in step 0, the Brosetuna repeatedly executes step S10, and only when it is determined that the vertical synchronizing signal V is being outputted, proceeds to step 811. Step 811
In step S4, the processor stops sending out the write enable signal W and returns to step S4.

If it is determined in step S9 that the scan command has not been issued, the processor moves to step S12 and stops sending out the forced feed command signal to the slider servo circuit 6. Next, the processor moves to step 313 and determines whether or not the vertical synchronization signal V is output from the separation circuit 26. When it is determined in step 813 that the vertical synchronization signal ■ is not being output, the processor repeatedly executes step 813, and only when it is determined that the vertical synchronization signal ■ is being output, the processor moves to step 814. . In step S14, the processor controls each section so that the video signal and audio signal recorded on the disc 2 are reproduced and supplied to the video output terminal 42 and the audio output terminal 16, 17, and immediately before proceeding to step S1. Resumes execution of the routine that was previously running.

The effects of the above operations will be explained with reference to FIG. FIG. 3(A) shows the tracking oven command signal a
, (B) is a waveform diagram of the forced feed command signal d sent to the slider servo circuit 6, (C) is a waveform diagram of the switching control signal d supplied to the changeover switch 30,
(D) is a waveform diagram of the vertical synchronizing signal (■) output from the separation circuit 26, and (E) is a waveform diagram of the write enable signal W.
FIG. When the scan command is issued, the transmission of the write enable signal W is stopped in synchronization with the generation of the vertical synchronization signal V, and rewriting of the contents stored in the RAM 33 is stopped. At the same time, the control signal d becomes high level, and the video signal written in the RAM 33 starts to be selectively output from the changeover switch 30. After this, the sending of the forced feed command signal S is started, and the slider 9 begins to be forcedly driven. The sending of this forced feed command signal continues until the scan command disappears.

Further, after the sending of the forced feed command signal A is started, the tracking oven command signal a is output for a period of 10 m5.

Due to the forced movement of the slider 9, the bias fim of the tracking actuator in the pickup 3 increases. Then, when the tracking servo loop becomes oven due to the tracking oven command signal a, the tracking actuator returns to the middle point of the movable range and the deviation amount becomes O, and the light spot for information detection moves over the tracks of the disk 2. do.

After this, 5ms is the time required for the tracking servo to lock in after the tracking open command signal a disappears and the tracking servo loop is closed.
When the period has elapsed, detection of the vertical synchronizing signal (2) in step S7 is started. When the vertical synchronization signal V is detected in step S7, the write enable signal W is sent out over the period from the disappearance of the vertical synchronization signal V to the generation of the next vertical synchronization signal, and the video signal for one field is sent to the RA.
The data is written to M33 and the stored contents of RAM33 are rewritten.

Furthermore, when the transmission of the write enable signal W is stopped and writing of one field's worth of video signals is completed, the tracking open command signal a is outputted again and the track jumping movement operation of the information detection light spot is started.

Therefore, immediately after one field of video signal is obtained from the disk after the track-jumping movement of the information detection light spot, the track-jumping movement is started again. Therefore, during the play operation during scanning, the storage contents of the RAM 33 are reliably rewritten using one field's worth of video signals, and at the same time, the duration of the play operation is shortened. As a result, the amount of deflection of the tracking actuator is reduced, the load on the tracking actuator is reduced, and failures are prevented.

In addition, since the number of tracks that the information detection point of the pickup jumps through when the tracking servo loop is opened is small, the difference in frequency between the video signals obtained immediately before and after the servo loop is opened is small, and the time base servo ( This reduces the burden on the time axis servo (time axis servo) and allows reproduced images with no color disturbances to be obtained even during scanning.

Effects of the Invention As detailed above, the scanning method according to the present invention is capable of scanning at least one field of information obtained from a recording disk during a play operation that is performed alternately with a track jumping operation in response to a scan command. Since the track jumping operation is started immediately after the video memory is rewritten with video information, the duration of the play operation is shortened, the amount of deflection of the tracking actuator is reduced, and failure of the tracking actuator is prevented. The Rukoto. At the same time, the number of tracks on which the information detection point of the pickup jumps is reduced, so the difference in frequency between the video signals obtained immediately before and after the track-jumping movement becomes small, and the time base servo (time base servo) This reduces the burden on the axis servo (axis servo) and allows reproduced images without color disturbance even during scanning.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an information reproducing device adopting the method according to the present invention, FIG. 2 is a flowchart showing the operation of the device shown in FIG. 1, and FIG. 3 shows signals of each part of the device shown in FIG. 1. FIG. 3 is a waveform diagram showing waveforms.

Claims (1)

[Claims] In an information reproducing apparatus having a video memory for storing video information obtained from a recording disk, high-speed reproduction is achieved by alternately performing a play operation and an operation of moving an information detection point of a pickup over tracks in response to a scan command. In the scanning method, the track skipping operation is performed immediately after the storage contents of the video memory are rewritten with at least one field worth of video information among the information obtained from the recording disk during the play operation. A scanning method in an information reproducing device characterized by activating.