JP3010867B2 - Writable disc player - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a writable disk reproducing apparatus suitable for use in reproducing a reproduction signal from a writable disk at a good C / N ratio during reproduction.

[0002]

2. Description of the Related Art Currently, optical disks capable of recording and reproducing data include write-once recording (Write Once Read Many type) in which data can be written only once and rewritable magneto-optical recording (Magneto-Optical memory). Phase change record (Phase
Change memory) method.

A disk recording and / or reproducing apparatus for recording data on a disk and / or reproducing data from the disk irradiates a laser to a magneto-optical recording MO rewritable with these write-once recording WOs, Recording is performed by applying heat by this laser irradiation. The recording method will be described. When data is recorded on a magneto-optical recording disk in the rewritable optical disk, the disk recording and / or reproducing apparatus lowers the coercive force of a portion heated by laser irradiation. At the same time, recording is performed by externally applying an external magnetic field to the heated portion to cause magnetization reversal according to the data. Each of the above-mentioned various recording media usually irradiates a laser having a lower output than that during recording in a disk recording and / or reproducing apparatus, and retrieves a reproduction signal by return light of the laser. As described above, the recording medium is heated by the irradiation of the laser during the reproduction.

[0004]

As described above, the magneto-optical disk serving as a recording medium retains the state of a magnetic thin film as a magneto-optical recording film, ie, data, by heating by laser irradiation during reproduction, as described above. Since the laser beam undergoes a change to cause a decrease in magnetic force, as described above, even if a laser having a low output is used for a long time, the characteristics of the reproduction signal of the magneto-optical disk will be deteriorated.

[0005] The disk shown in FIG. 3 has tracks formed in a spiral, for example, and recording and reproduction are performed along the tracks. This disk is a CAV type disk rotated at a constant rotation angular velocity. This CAV
The disc of the system is divided for each sector, and information such as an address is recorded in a head area of the sector. In addition, in the CAV system disk, one round of the disk corresponds to one frame. Therefore, when a still image is obtained from the disk, the end position of a certain track on the disk shown in FIG. end a of track one track before b
And jumps back to the previous track to repeatedly reproduce the same track.

However, due to the repetitive reproduction of the same track, the recording medium of the track changes its state of retaining data, and the C / N characteristics and the like of the reproduced signal are reduced as compared to immediately after recording. Would.

Therefore, in view of the above situation, the present invention provides a C / N just after recording on a recording medium even after repeated reproduction.
It is an object of the present invention to provide a writable disc reproducing apparatus capable of maintaining a characteristic and outputting a reproduction signal having a high C / N characteristic with a simple configuration even in normal reproduction and repeated reproduction.

[0008]

According to the present invention, there is provided a writable disk reproducing apparatus for reproducing information recorded on a writable disk in a laser output control for controlling a laser output applied to the disk. Means, storage means for storing a reproduction signal of an area that is repeatedly reproduced in accordance with a repetition reproduction command signal, switching control means for switching between a repetition reproduction signal from the storage means and a reproduction signal from the disk, A system controller for controlling the operation of each section of the disc reproducing apparatus, wherein the system controller has an optimum C / N characteristic by the laser output control from the laser output control means only at the first reproduction in the repetitive reproduction mode. The reproduction signal is stored in the storage means as a repetition reproduction signal, and is used for subsequent repetition reproduction. There repeating reproduction signal outputted from said memory means by obtained by switching control to output via the switching control means, to solve the problems described above.

[0009]

In the writable disk reproducing apparatus according to the present invention, when repeatedly reproducing the same track, the laser output control means is reproduced only once at the time of the first reproduction by the control signal from the system controller. A reproduction signal based on a laser output that provides an optimum C / N level is supplied to and stored in the storage unit, and the output signal from the storage unit is used as a repetition reproduction signal while suppressing the laser output during subsequent repetition reproduction. In this way, the switching control means is switched and controlled so that the data at the time of recording is not changed by the laser output at the time of reproduction. In particular, in the case of repetitive reproduction such as a so-called still jump for reproducing the same recorded portion, a reproduction signal having high C / N characteristics is output by reducing damage due to a thermal change of the recording medium.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a writable disk reproducing apparatus according to the present invention will be described with reference to the drawings.

FIG. 1 shows a schematic block circuit configuration of a writable disk reproducing apparatus according to the present invention.
In a disc reproducing apparatus for reproducing a writable disc, a laser power controller 12 which is a laser output control means for controlling a laser output applied to the disc 19, and a reproduction signal for an area which is repeatedly reproduced in response to a repetition reproduction command signal , A changeover switch 14 as switching control means for switching between a repetitive reproduction signal from the frame memory 13 and a reproduction signal from the disk, and an operation of each unit of the disk reproduction apparatus. System controller 15 to control
It consists of:

The operation of the disk reproducing apparatus for reproducing a writable disk will be described based on the circuit configuration shown in FIG. An external command input via the input terminal 11 is supplied to the system controller 15. The disk 19 mounted on a mounting table (not shown) is rotated by driving a spindle motor 18 according to a control signal supplied from the system controller 15.

An input video signal to be recorded is supplied to a video signal processing circuit 16 via an input terminal 10.
The video signal processing circuit 16 performs various kinds of signal processing, and a digital signal is sent to the laser power controller 12 via the modulation circuit 17 as modulated digital data.

When the system controller 15 detects that the external command is a recording mode command, the laser power controller 12 transmits a control signal to the laser power controller 12 so as to perform necessary laser output control at the time of recording according to the recording mode. It is supplied to the pickup 20. The modulated digital data is supplied to an optical pickup 20 and converted into a laser pulse, and the laser beam emitted from the optical pickup 20 is recorded at a target position on a disk 19.

When the system controller 15 detects that the input external command is in the reproduction mode, it supplies a control signal for controlling the laser power controller 12 in the reproduction mode. The laser power controller 12 controls the optical pickup 20 to emit an optimum laser output required for reproduction. The optimum laser output at the time of this reproduction is set to such a level that a reproduced signal having better C / N characteristics can be obtained as compared with the laser output at the time of recording.

The laser output from the optical pickup 20 is reflected by the disk 19 and returns. The optical pickup 20 detects the return light of the laser, converts it into an RF signal, and sends the RF signal to the demodulation circuit 21.

The demodulation circuit 21 converts a RF signal into a digital signal, and converts the RF signal into a time base collector (hereinafter abbreviated as TBC) 2.
Send to 2. The TBC 22 outputs an output signal obtained by performing time axis correction on the digital signal to the frame memory 13.
And to the terminal a of the changeover switch 14. The frame memory 13 switches an output signal in accordance with a control signal from the system controller 15 to the changeover switch 1.
4 is output to the terminal b side. The frame memory 13
Has a memory capacity for a region that is repeatedly played back, and for example, in the case of still image playback, has a memory capacity for at least one frame.

At the time of this reproduction, the system controller 15
Supplies a switching control signal to be output to the changeover switch 14, and controls the switch to output a normal reproduction signal by turning the switchover switch 14 to the terminal a side. Therefore, a normal reproduction signal is output from the output terminal 23 during reproduction.

Next, an external command supplied to the system controller 15 is a command for setting a repetitive reproduction mode,
For example, when the command is decoded as a so-called still-jump playback mode command for playing back a still image, the system controller 15 moves the optical pickup 20 from the end position of a certain track once per rotation of the disc in the repetitive playback mode. Control is performed so that the same track is repeatedly played back until a track jump is returned to the end of the previous track and a still jump release command is input as a new external command. For example, FIG.
If the command of the still jump playback mode is input during playback of the track number # 1003 shown in (a), the track number # 1003 is maintained after the end of the track number # 1003.
Is played continuously.

By the way, as described above, due to the repeated reproduction of the same track, the recording medium of the track changes its state of retaining data, and therefore the C / N characteristic of the reproduced signal is smaller than immediately after recording. And the like. In order to prevent the C / N characteristics of the reproduced signal from being reduced in the case of repeated reproduction, disc recording and / or
Alternatively, the reproducing apparatus reduces the laser output during reproduction as much as possible.

However, in general, when the laser output at the time of reproduction is small, the disk recording and / or reproduction apparatus is affected by noise or the like as the level of the reproduction signal decreases, and the RF as the reproduction signal is reduced. The C / N characteristics and S / N characteristics of the signal will be reduced. Therefore, when repeatedly reproducing the same track, the laser power controller 1
Reference numeral 2 denotes a control signal for controlling the laser output in the repetitive reproduction mode (still jump).
Supply 0. The control of the laser power controller 12 reproduces only one time of the first reproduction with a laser output capable of obtaining a reproduction signal of an optimum C / N level and outputs an RF signal.

Next, the laser output level is lowered at the reproduction laser output level arrow shown in FIG.
At this time, the level of the C / N characteristic of the RF signal decreases at the boundary of the arrow as shown in FIG. Similarly, demodulation circuit 2
As shown in FIG. 2D, the S / N characteristic level of the output signal from 1 also decreases at the boundary of the arrow. The characteristic level of the signal of the reproduction signal from the disc at the time of repetitive reproduction is supplied to the frame memory 13 via the demodulation circuit 21 and the TBC 22. In order to avoid this, the frame memory 13 sets the write enable signal to the disabled state after the repetition of the reproduction mode, and inhibits the writing.

In order to obtain the optimum reproduction signal of the C / N level, the writable disk reproducing apparatus supplies the optimum laser output only once to obtain the first reproduction signal.
In the subsequent repetitive reproduction, the output of the laser can be suppressed so that the recording medium does not change the state of retaining data. Therefore, it is possible to maintain the C / N characteristics immediately after the recording in the recording medium.

As shown in FIG. 2 (e), the data of one frame taken in the repetitive reproduction is supplied to the frame memory 13 in the order of the track numbers shown in FIG. 2 (a). . System controller 1
5 by turning on the read enable signal 5 and reading the read clock from the frame memory 13 with, for example, a clock corresponding to the scanning line of the monitor to be used, a still image is continuously reproduced and supplied to the terminal b of the changeover switch 14. You. The changeover switch 14 is connected to the system controller 1
5 is controlled so as to fall to the terminal b side. In this way, a reproduction signal having a high C / N characteristic can be maintained through the output terminal 23 even during the repetitive reproduction mode.

Here, the schematic block circuit diagram shown in FIG. 1 shows a state in the repetitive reproduction mode.

By using the output signal from the frame memory 13, the S / S of the output signal from the output terminal 14 is
The N characteristic, as shown in FIG. 2C and FIG. 2D, is reduced during the operation of the writable disc reproducing apparatus as shown in FIG. In particular, high S / N characteristics can always be maintained even during repeated reproduction. The output video signal output from the output terminal 23 is output with a delay of one track with respect to the track number in the frame memory 13 in FIG.

The system controller 15 outputs a write enable signal so as to store the reproduction signal supplied to the frame memory 13 in the normal reproduction mode as well as in the repetitive reproduction mode, and outputs the reproduced digital signal. The data is taken into the frame memory 13 as data. It should be noted that the system controller 15 can also control so that an area that requires repeated reproduction, for example, only a frame, is loaded into the frame memory 13.

In the still reproduction after the first still reproduction, the laser power controller 12 lowers the laser output from the optical pickup 20. Here, the laser output to be lowered is not completely turned off, but the focus jump, the thread servo for performing coarse head feed control, and the tracking servo for performing precise head feed control are applied, and this still jump reproduction mode is performed. When the optical pickup 20 is released, the optical pickup 20 can be operated immediately.
However, the laser output required for holding the still image at the end position of the track on which the still image is reproduced is reduced to the laser output required.

In the writable disc reproducing apparatus, another optical pickup 2 in the repetitive reproduction mode is used.
0 as the control method for the optical pickup 20
For example, a method of performing, for example, tracking servo control with the laser output that is the optimum laser output along the track without lowering the laser output may be used. By controlling the position of the optical pickup 20 in this way, even if the data is repeatedly reproduced, the same reproduction area can be prevented from being heated by laser irradiation, and the data recorded on the recording medium can be prevented from deteriorating. This optical pickup control requires time to move the optical pickup 20 to the end position of the track on which the still image was reproduced when returning to the normal reproduction mode. However, it is necessary to control the laser output while keeping the laser output constant. Since this is not done, the circuit configuration can be further simplified.

Also, the system controller 15 stops the operation of writing in the frame memory 13. For example, when the still image reproduction is continuously repeated for a long time, the rotation speed of the spindle motor for rotating the disk can be reduced, or the rotation of the spindle motor can be stopped. As a result, the life of the motor can be extended.

Incidentally, the writable disc reproducing apparatus is
Obviously, it is possible to cope with a disk playback-only device. In the above-described embodiment, the signal recorded on the disc is described as a reproduction of a video signal such as a still image.
The present invention is not limited to the type of the recording data, and can be used for repetitive reproduction of document images, computer processing data, character data, and audio data included between so-called AB section jumps.

Further, the disc system is not limited to the CAV system described above. From the viewpoint of preventing data deterioration of a recording medium, for example, when one frame of data is fetched from a CLV system disc and repeatedly reproduced. Is clearly an effective method.

By controlling the laser output according to each mode with such a configuration, the state at the time of recording can be maintained. In particular, the reproduction is repeatedly performed like a still jump for reproducing the same recorded portion. Even so, it is possible to reduce the damage due to the thermal change of the recording medium and maintain the reproduced signal having high C / N characteristics.

In addition, when the above-mentioned repetitive reproduction is performed because the reproduction RF signal is stored in the still jump, the rotation of the disk is reduced or the rotation is stopped, so that the life of the spindle motor can be extended. . The writable disk reproducing apparatus can also reduce power consumption by stopping or reducing the operation of each circuit in the still jump reproduction mode.

[0035]

As is apparent from the above description, according to the writable disk reproducing apparatus of the present invention, in a disk reproducing apparatus for reproducing information recorded on a writable disk, a laser for irradiating the disk is used. Laser output control means for controlling the output; storage means for storing a reproduction signal of an area which is repeatedly reproduced in response to a repetition reproduction command signal; and switching between the repetition reproduction signal from the storage means and the reproduction signal from the disk. Switching control means for controlling, and a system controller for controlling the operation of each unit of the disk playback device, the system controller,
In the repetitive reproduction mode, the optimal C / C is controlled only by the laser output control from the laser output control means during the first reproduction.
A reproduction signal having N characteristics is stored in the storage means as a repetition reproduction signal, and switching control is performed so that a repetition reproduction signal output from the storage means is output via the switching control means in the subsequent repetition reproduction. By
Data can be maintained for a long time without changing the state of data at the time of recording.

In particular, even if the reproduction is repeatedly performed like a still jump for reproducing the same recorded portion, the damage due to the thermal change of the recording medium is reduced, and the reproduction signal having high C / N characteristics can be maintained. .

In addition, when the reproduction RF signal is stored in the still jump and the above-mentioned repetitive reproduction is performed, the rotation of the disk is reduced or stopped, so that the life of the spindle motor can be extended. .

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic block configuration of one embodiment of a writable disc reproducing apparatus according to the present invention.

FIG. 2 is a diagram for explaining a method of connecting data and performing continuous reproduction by the circuit configuration shown in FIG. 1;

FIG. 3 is a diagram illustrating a still jump in a writable disc.

[Explanation of symbols]

10, 11 ... input terminal 12 ... laser power controller 13 ... frame memory 14 ... ······· Changeover switch 15 ··· System controller 19 ··· Disk 20 ········ ..Optical pickup 23 ........ Output terminal

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) G11B ^7/ 00-7/013 G11B 11/00-13/06 G11B 20/02 H04N 5/85

Claims (1)

(57) [Claims] 1. A disc reproducing apparatus for reproducing information recorded on a writable disc, comprising: a laser output control means for controlling a laser output applied to the disc; and an area which is repeatedly reproduced in response to a repetitive reproduction command signal. Storage means for storing the reproduction signal of the disk, switching control means for switching between the repeated reproduction signal from the storage means and the reproduction signal from the disk, and a system controller for controlling the operation of each section of the disk reproduction apparatus. In the repetitive reproduction mode, the system controller stores a reproduction signal having an optimal C / N characteristic in the storage means as a repetition reproduction signal by the laser output control from the laser output control means only at the first reproduction. During the repetitive reproduction of the above, the repetitive reproduction signal output from the storage means Writable disk reproducing apparatus characterized by comprising by switching control to output via the control means.