JPH05144007A - Write enable disk reproduction device - Google Patents

Abstract

PURPOSE:To reproduce with high C/N reproducing signals so as to obtain reproduced signals which have the same characteristics as the initial C/N characteristics of the recorded medium. CONSTITUTION:During recording mode, the input video signals from an input terminal 10 are written on a disk 19 in accordance with the external commands supplied to a system controller 15 from an input terminal 11, the laser output from an optical pickup 20 is controlled by a laser power controller 12. Similarly, during normal reproduction and first round of the repeated reproduction, the reproduced signals are supplied to a frame memory 13 being controlled by the laser power controller 12 so as to irradiate with an optimum laser output. Especially, during repeated reproduction, the system controller 15 performs control to suppress a laser output and to control so that output signals from the frame memory 13 are outputted through a changeover switch 14.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Currently, optical discs capable of recording / reproducing data are classified into a write once read many type capable of writing data only once and a rewritable magneto-optical recording medium. Phase change recording (Phase
There are two methods of change memory).

A disk recording and / or reproducing apparatus for recording data on a disk and / or reproducing data from the disk irradiates the magneto-optical recording MO rewritable with the write-once recording WO with a laser, and Recording is performed by applying heat by this laser irradiation. This recording method will be described. When recording data on a magneto-optical recording type disc of the rewritable optical disc, the disc 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. The various recording mediums described above generally emit laser light having a weaker output than that during recording in a disk recording and / or reproducing apparatus, and a reproduction signal is extracted by the return light of the laser. As described above, the recording medium is heated to some extent by the irradiation of the laser during reproduction.

[0004]

By the way, in the magneto-optical disk which is a recording medium, the state of the magnetic thin film as the magneto-optical recording film, that is, the data storage, is maintained by the heating by the laser irradiation during the reproduction as described above. As described above, even if a laser having a weak output is used for many years, the characteristics of the reproduction signal of the magneto-optical disk are deteriorated because the magnetic field is changed so as to cause a decrease in magnetic force.

The disc shown in FIG. 3 has, for example, spirally formed tracks, and recording / reproduction is performed along the tracks. This disc is a CAV type disc that is rotated at a constant angular velocity. This CAV
The disc of the method is divided into sectors, and information such as an address is recorded in the head area of the sector. Further, in the case of the CAV type disc, one round of the disc corresponds to one frame, and therefore, when a still image is obtained from the disc, the end position of a certain track shown in FIG. end a of the track immediately before b
It can be obtained by jumping back to the track and playing back the same track repeatedly.

However, the repetitive reproduction of the same track causes the recording medium of the track to change to a state in which the data is held, so that the C / N characteristic of the reproduction signal is deteriorated as compared with immediately after recording. Will end up.

Therefore, in view of the above situation, the present invention has a C / N immediately after recording recorded in a recording medium even after repeated reproduction.
It is an object of the present invention to provide a writable disc reproducing apparatus which can maintain a characteristic and output a reproduced signal having a high C / N characteristic even in normal reproduction and repeated reproduction with a simple structure.

[0008]

A writable disc reproducing apparatus according to the present invention is a disc reproducing apparatus for reproducing information recorded on a writable disc, and a laser output control for controlling a laser output applied to the disc. Means, storage means for storing a reproduction signal of an area which is repeatedly reproduced in response to the repeated reproduction command signal, and switching control means for switching control 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 part of the disc reproducing apparatus, wherein the system controller provides the optimum C / N characteristic by the laser output control from the laser output control means only during the first reproduction in the repeated reproduction mode. The reproduced signal is stored in the above-mentioned storage means as a repeated reproduced signal, and is repeatedly reproduced thereafter. 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 disc reproducing apparatus according to the present invention, when the same track is repeatedly reproduced, the laser output control means is reproduced by the control signal from the system controller only once at the first reproduction. A reproduction signal by a laser output that gives an optimum C / N level is supplied to the storage means and stored therein, and the laser output is suppressed during the subsequent repeated reproduction and the output signal from the storage means is used as the repeated reproduction signal. As described above, the switching control means is controlled so as to prevent the data at the time of recording from being changed by the laser output at the time of reproducing. Particularly, in the case of repetitive reproduction such as so-called still jump in which the same recorded portion is reproduced, damage due to heat change of the recording medium is reduced and a reproduction signal having high C / N characteristics is output.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a writable disc 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 disc 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 of a region which is repeatedly reproduced in response to a repeated reproduction command signal. The frame memory 13 which is a storage means for storing the data, the changeover switch 14 which is a changeover control means for changing over and controlling the repeated reproduction signal from the frame memory 13 and the reproduction signal from the disc, and the operation of each part of the disc reproducing apparatus. System controller 15 to control
It consists of and.

The operation of the disc reproducing apparatus for reproducing a writable disc 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) drives the spindle motor 18 to rotate in response to a control signal supplied from the system controller 15.

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

When the system controller 15 detects that the external command is a recording mode command, the laser power controller 12 optically outputs a control signal so as to perform a laser output control required for recording according to the recording mode. It is being supplied to the pickup 20. The modulated digital data is supplied to the optical pickup 20 and converted into a laser pulse, and the laser emitted from the optical pickup 20 records the target position on the disk 19.

Further, 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 reproduction is such that a reproduction signal having a good C / N characteristic 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 this laser, converts it into an RF signal, and sends the RF signal to the demodulation circuit 21.

The demodulation circuit 21 converts the RF signal into a digital signal and a time base collector (hereinafter abbreviated as TBC) 2
Send to 2. The TBC 22 outputs the output signal obtained by performing the time base correction to the digital signal to the frame memory 13
To the terminal a side of the changeover switch 14. The frame memory 13 switches the output signal according to the control signal of the system controller 15
4 is output to the terminal b side. The frame memory 13
Has a memory capacity of a region to be repeatedly reproduced, and for example, in the case of still image reproduction, has a memory capacity of at least one frame.

During this reproduction, the system controller 15
Supplies the changeover control signal to be output to the changeover switch 14 and tilts it to the terminal a side of the changeover switch 14 so as to output a normal reproduction signal. Therefore, during reproduction, a normal reproduction signal is output from the output terminal 23.

Next, the external command supplied to the system controller 15 is a command to set the repeat reproduction mode,
For example, when the command is decoded in a so-called still jump reproduction mode for reproducing a still image, the system controller 15 causes the optical pickup 20 to move once every one revolution of the disk from the end position of one track in the repeated reproduction mode. A control is performed so that the track jumps back to the end of the previous track, and the same track is repeatedly reproduced until a still jump cancel command is input as a new external command. Figure 2
If a still jump reproduction mode command is input during reproduction of the track number # 1003 shown in (a), the track number # 1003 continues even after the end of the track number # 1003.
To play continuously.

By the way, as described above, by repeatedly reproducing the same track, the recording medium on the track changes to a state in which the data is held. Therefore, the C / N characteristic of the reproduced signal is higher than that immediately after recording. There was a problem that the etc. In order to prevent the deterioration of the C / N characteristic of the reproduced signal when repeatedly reproduced, the disc recording and / or
Alternatively, the reproducing device minimizes the laser output during reproduction.

However, in general, when the laser output at the time of reproduction is small, the disk recording and / or reproducing apparatus is affected by noise or the like as the level of the reproduction signal decreases, and the reproduction signal RF is generated. The C / N characteristic and S / N characteristic of the signal are deteriorated. Therefore, when repeatedly reproducing the same track, the laser power controller 1
Reference numeral 2 denotes an optical pickup 2 which is a control signal for controlling the laser output in the repeated reproduction mode (still jump).
Supply to 0. The control of the laser power controller 12 reproduces only 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 boundary of the reproducing laser output level arrow shown in FIG. 2 (b).
At this time, the C / N characteristic of the RF signal decreases in level at the arrow as shown in FIG. Similarly, demodulation circuit 2
The S / N characteristic level of the output signal from 1 also decreases at the boundary of the arrow as shown in FIG. With respect to the characteristic level of the signal of the reproduction signal from the disc during the repeated reproduction, the reproduction signal whose level has been lowered is supplied to the frame memory 13 through the demodulation circuit 21 and the TBC 22. In order to avoid this, the frame memory 13 sets the write enable signal to the disable state after the repetitive reproduction mode transition, and prohibits the writing.

In order to obtain the optimum C / N level reproduction signal, the writable disc 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 to the state of holding the data. Therefore, it is possible to maintain the C / N characteristic immediately after recording in the recording medium.

As for the data for one frame taken in by the repeated reproduction, as shown in FIG. 2 (e), the frame memory 13 is supplied with the data of the track numbers in the order shown in FIG. 2 (a). .. System controller 1
By turning on the read enable signal of No. 5 and reading the read clock from the frame memory 13 at a clock corresponding to the scanning line of the monitor to be used, for example, still images are continuously reproduced and supplied to the terminal b of the changeover switch 14. It The changeover switch 14 is the system controller 1
A switching control signal from 5 controls the terminal to be turned 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 this repeated reproduction mode.

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

By using the output signal from the frame memory 13, S / of the output signal from the output terminal 14 can be obtained.
2 (c) and 2 (d), the N characteristic is lowered at the level of the arrow, but as shown in FIG. 2 (g), the writable disc reproducing device is in operation. In particular, even during repeated reproduction, high S / N characteristics can always be maintained. The output video signal output from the output terminal 23 is output one track later than the track number in the frame memory 13 of FIG.

Not only in the repetitive reproduction mode, but also in the normal reproduction mode, the system controller 15 outputs a write enable signal so as to store the reproduction signal supplied to the frame memory 13 and outputs the reproduced digital signal. It is stored in the frame memory 13 as data. The system controller 15 can also control so that only the area that requires repeated reproduction, for example, only the frame is loaded into the frame memory 13.

In the still reproduction after the first still reproduction, the laser power controller 12 reduces the laser output output from the optical pickup 20. Here, the laser output to be reduced is not completely turned off, but this still jump reproduction mode is applied by applying focus servo, sled servo for rough head feed control, and tracking servo for precise head feed control. When the optical pickup 20 is released, the optical pickup 20 can be operated immediately.
However, the laser output is lowered to the laser output required to hold the still image at the end position of the track where the still image is reproduced.

Another optical pickup 2 in the repetitive reproduction mode in the writable disc reproducing device
As a control method for 0, the optical pickup 20
For example, a method may be used in which, for example, tracking servo control or the like is performed with the laser output that remains the optimum laser output along the track without reducing the laser output. By controlling the position of the optical pickup 20 in this manner, it is possible to prevent deterioration of data recorded on the recording medium by avoiding heating of the same reproduction area due to laser irradiation even if the reproduction is repeated. This optical pickup control takes time to move the optical pickup 20 to the end position of the track on which the still image is reproduced when returning to the normal reproduction mode, but it is necessary to control the laser output by keeping the laser output constant. Since it does not, the circuit configuration can be further simplified.

The system controller 15 also stops the writing operation of the frame memory 13. For example, when the still image reproduction is continuously repeated for a long time, it is possible to reduce the rotation speed of the spindle motor that rotates the disk or stop the rotation of the spindle motor. As a result, the life of the motor can be extended.

The writable disc reproducing device is
Obviously, it can also be applied to a disc reproduction-only device. In the above-mentioned embodiment, the reproduction of the video signal such as a still image from the signal recorded on the disk is described.
The type of the recorded data is not limited to the above, and it can be used for repetitive reproduction of a document image, computer processed 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, and from the viewpoint of preventing the deterioration of the data of the recording medium, for example, when one frame of data is fetched and repeatedly reproduced in the CLV system disc. Is also 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, and in particular, repetitive reproduction such as a still jump for reproducing the same recorded portion is performed. However, the damage due to the heat change of the recording medium can be reduced and the reproduction signal having high C / N characteristics can be maintained.

Further, since the reproduction RF signal is stored in the still jump and the reproduction is repeatedly performed, the rotation of the disk is reduced or stopped, so that the life of the spindle motor can be extended. .. This writable disc reproducing device can also reduce power consumption by stopping or reducing the operation of each circuit in the still jump reproducing mode.

[0035]

As is apparent from the above description, according to the writable disc reproducing device of the present invention, in the disc reproducing device for reproducing the information recorded on the writable disc, the laser for irradiating the disc is irradiated. A laser output control means for controlling the output, a storage means for storing a reproduction signal of an area repeatedly reproduced in response to a repeated reproduction command signal, and a switching between the repeated reproduction signal from the storage means and the reproduction signal from the disc. It has a switching control means for controlling and a system controller for controlling the operation of each part of the disc reproducing apparatus, and the system controller comprises:
In the repetitive reproduction mode, the optimum C / is controlled by the laser output control from the laser output control means only at the first reproduction.
The N-character reproduction signal is stored in the storage means as a repeated reproduction signal, and switching control is performed so that the repeated reproduction signal output from the storage means is output through the switching control means during subsequent repeated reproduction. Due to
It is possible to maintain the data for a long time without changing the state of the data at the time of recording.

In particular, even if the reproduction is repeated such as the still jump for reproducing the same recording portion, the damage due to the heat change of the recording medium can be reduced and the reproduction signal having a high C / N characteristic can be maintained. ..

Further, since the reproduction RF signal is stored in the still jump and the reproduction is repeatedly performed, the rotation of the disk is reduced or stopped, so that the life of the spindle motor can be extended. ..

[Brief description of drawings]

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

FIG. 2 is a diagram illustrating a method for connecting and continuously reproducing data by the circuit configuration shown in FIG.

FIG. 3 is a diagram illustrating a still jump on 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

Claims (1)

[Claims] 1. A disc reproducing apparatus for reproducing information recorded on a writable disc, and a laser output control means for controlling a laser output for irradiating the disc, and a region repeatedly reproduced in response to a repeated reproduction command signal. Storage means for storing the reproduction signal of the disc, switching control means for switching control between the repeated reproduction signal from the storage means and the reproduction signal from the disc, and a system controller for controlling the operation of each part of the disc reproducing device. Then, the system controller causes the storage means to store the reproduction signal having the optimum C / N characteristic as the repeated reproduction signal by the laser output control from the laser output control means only during the first reproduction in the repeated reproduction mode. The repeated reproduction signal output from the storage means during the repeated reproduction of Writable disk reproducing apparatus characterized by comprising by switching control to output via the control means.