JPH0816981B2 - Rewritable photochromic optical disk playback device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a rewritable photochromic optical disc reproducing apparatus for reproducing a signal on a photochromic recording medium.

BACKGROUND ART A rewritable optical disc (EDRA that can be recorded, played, and erased)
W) is being developed.

As such an optical disc, a magneto-optical recording utilizing the recording film magneto-optical effect of an alloy is well known.
Recently, it has been studied to use an organic photochromic material capable of high density recording for a recording film of an optical disc.

The organic photochromic material is a compound that repeats coloring and decoloring in response to light. For example, as shown in the light absorption spectrum distribution chart of FIG. 7, when light of wavelength B is absorbed, stable state X changes to metastable state Y. Then colored, metastable state Y
When the light or heat of wavelength A is absorbed, the substance returns to the original substance again and has a property of decoloring. As such an organic photochromic material, for example, there is a material such as thioindigo which uses an isomerization reaction by light, or a spiropyran or fulgide which uses a ring-opening and ring-closing reaction or a redox reaction.

A rewritable optical disk utilizing reversible light and thermal isomerization reaction such as an organic photochromic material has a recording layer 2 containing an organic photochromic material as shown in FIG.
Is formed as a thin film on the transparent substrate 1, and the aluminum reflection layer 3 is formed as a thin film on the recording layer 2. Board 1
Grooves for tracking, pre-pits for controlling writing or reading of data, and pre-address 5 are formed in advance by stamping or the like on the main surface of, and are in a so-called formatting state.

To record information on this optical disc, light and heat energy are applied in spots to the recording layer 2 by a writing laser beam through an optical system of a pickup including an objective lens 4 to actively cause an isomerization reaction or the like. , A sequence of spots whose color tone or refraction is changed is formed. The reproduction of information from this optical disc is performed by irradiating a reading laser beam of another wavelength and reading the recorded spot train.

In this way, an EDRAW disc capable of relatively high density recording can be obtained.

By the way, the organic photochromic material absorbs energy every time it is irradiated with a low-level reading laser beam, and gradually reacts, and the pits formed on the optical disk gradually disappear. On the other hand, in playing an optical disk, it is indispensable to irradiate the track with beam light from the pickup to perform tracking and reading of an address signal, and the number of times of reading from the optical disk is limited.

SUMMARY OF THE INVENTION [Object of the Invention] Therefore, an object of the present invention is to provide a rewritable photochromic optical disk reproducing apparatus capable of suppressing disappearance of a recording information signal.

[Structure of the Invention] A rewritable photochromic optical disk reproducing apparatus of the present invention is a reproducing apparatus for reading and outputting an information signal recorded on a track of a re-recordable photochromic optical disk in response to a read command, and in response to the read command. Reading means for reading and erasing an information signal at a reading point for tracking a track by a track, and signal processing means for sequentially storing the information signals read by the reading means in a memory and reading the information signals stored in the memory in a storage order. , And writing means for writing the information signal read from the memory at a writing point immediately following the reading point on the track.

[Advantageous Effects of the Invention] According to such a configuration, at the same time that the information signal is read from the data area on the track of the photochromic optical disk in response to the read command, the recorded contents of the data area from which the information signal is read are erased. Since the same signal as the information signal read to the erased portion is rewritten, the recording state of the recording information signal is updated during the performance of the photochromic recording medium.

Example An example of the present invention will be described below with reference to FIG.

In FIG. 1, the disk 11 having the organic photochromic layer is rotationally driven by a spindle motor (not shown) and is controlled to a predetermined speed by a spindle servo. The reading pickup 12 converges the beam light A guided by the half mirror 14 from the laser generator 13 by a focus servo to form a light spot of a predetermined diameter on the track, and the tracking servo using the groove of the substrate 1 Make the light spot follow the track. The laser generator 13 generates, for example, a beam light having a wavelength of 632.8 [nm] H
It consists of an e-Ne laser device.

The reflected beam light modulated by the pits on the track is converted by the photoelectric conversion unit 15 into an electric signal having a level corresponding to the amount of reflected light. This electric signal is supplied to the signal reproducing section 16 and the pre-address reading section 17 as a read signal. Circuit 12
Reference numerals 15 to 15 constitute reading means.

The signal reproducing unit 16 demodulates the read signal into a PWM signal, further digitizes it, and supplies it to the buffer memory 18 and a signal demodulating system (not shown). The pre-address reading unit 17 demodulates, for example, an address signal added to the head position of each data block from the read signal, detects the address of the demodulated information signal, and outputs this to the read / write controller 19 and a performance control device (not shown). Supply.

The performance control device controls the operation of the entire player. For example, when the control information of the address signal of the data block and the demodulated information signal is supplied, the generation and disappearance timings of the erase command, the write command, the read command, etc. Can be controlled appropriately.

The read / write controller 19 is a microprocessor, RO
It is composed of M, RAM, etc. The buffer memory 18 supplies a storage signal to one input end of the signal selection switch 20 in response to a read command from the read / write controller 19.

The other input end of the signal selection switch 20 is supplied with the output from the buffer memory 21 storing the information signal to be recorded on the disc. The signal selection switch 20 supplies one of the input signals to the modulation input terminal of the optical modulator 23 via the A / D converter 22 in response to the selection command from the read / write controller 19. Signal reproducing unit 16, buffer memory 18 and A / D converter 2
2 constitutes a signal processing means.

The optical modulator 23 uses, for example, 350 [n from the laser generator 24.
m] of the ultraviolet laser beam B is intermittently turned on and off. The laser light B is guided to the writing pickup 26 by the half mirror 25. The writing pickup 26 converges the beam light B by a focus servo to form a light spot having a predetermined diameter on the track, and the tracking servo causes the light spot to follow the track. The reflected beam light modulated by the pits on the track is converted by the photoelectric conversion unit 27 into an electric signal having a level according to the amount of reflected light. This electric signal is supplied to the pre-address reading unit 28 as a read signal. The pre-address reading unit 28 demodulates the address signal added to the head position of the data block from the read signal, detects the address of the demodulated information signal, and supplies this to the read / write controller 19 and the performance control device. Circuits 23-27
Constitutes a writing means.

Light spot a due to light beams A and B of the pickup
2 and b are arranged close to each other on the same track as shown in FIG. 2, but it is also possible to arrange them at two positions on the same track which face each other across the center of the disk, or at different tracks. is there.

Next, the erase operation, the write operation, and the read operation of the device will be sequentially described.

First, the performance control device executes the spindle servo, and the focus servo, the tracking servo, and the tangential servo are executed for the low-level light spots a and b emitted by the read pickup 12 and the write pickup 26. The performance control device issues an erasing command when detecting an address immediately before the data block where erasing of data should start, and erases the erasing command when detecting an address where erasing of data should end.

When the read / write controller 19 receives the erase command from the performance controller, the read / write controller 19 moves to the third
The erase operation subroutine shown in the figure is executed. It is determined whether or not the address of the data block is supplied from the pre-address reading unit 17 (step S11). When the address is supplied, the position of the light spot is at the head of the information signal writing area of the data block, so the read / write controller 19 increases the output to the laser generator 13 to erase the information signal from the beginning of the data block. Command and laser light A
The level of. When the track is irradiated with the beam light A having a large level, the recording layer carrying the information signal on the track becomes a colorless body X, the pits disappear, and the recorded data is cleared. It should be noted that the substrate 1 of the disk 11 is provided with tracking grooves and pre-pits for carrying the addresses of the data blocks, but these are not erased by the irradiation of light, so the recorded information signal (write pit ) Disappears (step S12). If there is no erase command from the performance control device, the information signal of the next data block should not be erased, so it is determined whether or not there is an erase command. If it exists, the erasing of the information signal is continued (step S13). If there is no erase command, it is determined whether or not an address is supplied from the pre-address reading unit 17 to stop the signal erase at the end portion of the data block (step S14). When the address is supplied, the laser generator 13 is instructed to reduce the output in order to prevent the information signal from being erased, and the level of the light beam A is set to a low level necessary for tracking (step S15).

In this way, when the data block of the required portion is cleared, the read / write controller 19 returns to the main control program.

The write operation will be described. The writing operation is a series of operations for writing an external information signal to the disc, and an information signal to be recorded is supplied and stored in the buffer memory 21 from an external signal processing circuit or the like (not shown). When the performance control device supplies a write command to the read / write controller 19 to write an external information signal to the disk, the read / write controller 19
A main control program 19 executes a write operation subroutine shown in FIG.

When data is already recorded in the data block in which the external information signal is to be recorded, the performance controller issues an erase command and a write command at appropriate timings. By executing the write operation subroutine described in 1. in parallel, the information signal of the data block in which the external information signal is to be written is erased by the pickup 12 in advance, and then the external information is written by the pickup 26, and the double writing is performed. Prevents read errors due to data loading. Normally, the performance control device adjusts the existence periods of the erase command and the write command, respectively, so that the number of erased data blocks and the number of blocks in which data is written are adjusted, but, for example, an audio signal or a video signal is recorded. In this case, there is no particular problem even if the data blocks that are slightly larger than the data blocks to be written are erased.

First, the read / write controller 19 uses the buffer memory 21.
The signal selection switch 20 is switched to the memory 21 side in order to relay the information signal stored in the optical modulator to the optical modulator (step S23).
The read / write controller 19 increases the output of the laser generator 24 in order to write the external information signal when the address is supplied from the pre-address reading unit 28 in order to write from the beginning of the recording area of the information signal of the data block. (Step S2
Five). Then, the reading of the external information signal held in the buffer memory 21 is instructed (step S26). Buffer memory
In response to this, 21 outputs an external information signal to be stored in one data block. The output of the buffer memory 21 is converted into a PWM signal by the A / D converter 22, and the optical modulator
Supplied to 23. The large-level beam light B interrupted by the optical modulator 23 irradiates the track from the approximate head position of the data block from which data has been erased. By the irradiation of the beam light B, pits of the colored body Y are formed in the recording layer.
When the address of the next data block is supplied from the pre-address reading unit 28 (step S27), it is determined whether or not the write command continues to exist (step S28). When the write command is present, steps S26 to S28 are repeated to write the external information signal for each data block. When the write command does not exist, the data writing has been completed, and therefore an output reduction command is issued to the laser generator 24 in order to set the output of the laser B to a low level such that tracking can be performed (step S29). ), Return to the main control program.

In this way, the external information signal is supplied to the optical modulator 23 via the buffer memory 21, the signal selection switch 20, and the A / D converter 22, and is converted into the intermittent beam light B. The beam light B is guided onto the track by the write pickup 26 and formed as pits of the colored body Y on the recording layer.

The read operation will be described with reference to FIGS. 5 (A) and 5 (B).

When the read / write controller 19 receives a read command from the performance control device in the standby state, the read / write controller 19 shifts from the main control program to the subroutine shown in FIG. 5 and executes the subroutine (A) for the read pickup system to read the information signal. Reading and erasing are performed, and the subroutine (B) is executed for the write pickup system to rewrite the read information signal.

First, the read / write controller 19 detects the supply of an address from the pre-address reading unit 17 (step S4).
1) This address is stored as the reading start position (step S42), and the laser generator 13 is instructed to increase the output.
As a result, when the recording signal on the track is read, the information signal recorded in the data block is erased almost at the same time (step S43). The information signal read out is the signal reproduction section.
It is sequentially stored in the buffer memory 18 via 16. The read / write controller 19 continues reading the recording signal and erasing the information signal until the read command disappears. When the read command disappears (step 44), the address of the data block immediately after that is detected (step S45), and this is stored as the read end position (step S46). And the laser generator
The output of 13 is decreased to stop erasing the information signal, and the process returns to the main control program.

Thus, in subroutine (A), the information signal is read from the disk and erased at the same time in response to the presence of the read command.

On the other hand, the read / write controller 19 executes the subroutine (B) for the write pickup system and causes the signal selection switch 20 to select the output of the buffer memory 18 (step S51). When the address supplied to the read / write controller 19 by the pre-address reading unit 28 matches the address stored in step S42, the laser generating unit 24 is instructed to increase the output (steps S52, 53) and is held in the buffer memory 18. The information signal is output for one data block (step S54). As a result, the erased information signal is rewritten in the erased data block. When the detection address is supplied from the pre-address reading unit 28, it is determined whether or not this matches the read end address stored in step S46 (steps S55, 56). If they do not match, data writing to the data block is continued and the read information signal is rewritten (steps S54-5).
6). When the read end address is detected, the read / write controller 19 instructs the laser generator 24 to reduce the output and stops the writing of the information signal because the information signal has not been read or erased after this position. (Step S57). Then, it returns to the main control program.

In this way, since the read information signal is re-recorded in the erased data block, the disappearance of pits due to the reading of the information signal is suppressed.

There are two recording modes of the information signal: a case where colored pits are formed on a colorless track as in the above-described embodiment, and a case where colorless pits are formed on a colored track. The wavelengths (first wavelength and second wavelength) of the light spots of the reading unit and the writing unit are selected according to these recording modes.

As described above, in the write-type photochromic optical disc reproducing apparatus of the present invention, the information signal recorded on the track of the photochromic optical disc is erased while being read according to the read command, and the read information signal is erased. Since the data area is rewritten, it is preferable that the recording state of the recording information signal is updated during the performance of the photochromic recording medium and the deterioration of the recording state due to the reading of the recording information signal as in the conventional case is eliminated.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a diagram for explaining a positional relationship between the light spots a and b, and FIG. 3 is an erasing operation of the read / write controller 19. 4 is a flowchart for explaining the write operation of the read / write controller 19, and FIGS. 5A and 5B are flowcharts for explaining the read operation of the read / write controller 19. 6
FIG. 7 is a diagram for explaining a disc using a photochromic recording medium, and FIG. 7 is a diagram for explaining characteristics of the photochromic recording medium. Explanation of main part code 12 …… Reading pickup 18 …… Buffer memory 19 …… Reading / writing controller 26 …… Write pickup

Claims (2)

[Claims] 1. A rewritable photochromic optical disk reproducing device for reading and outputting an information signal recorded on a track of a re-recordable photochromic optical disk according to a read command, wherein the track is tracked according to the read command. Reading means for erasing while reading the information signal at a reading point, and signal processing means for sequentially storing the information signals read by the reading means in a memory and reading the information signals stored in the memory in a storage order. A rewritable photochromic optical disk reproducing apparatus comprising: a writing unit that writes the information signal read from the memory at a writing point immediately following the reading point on the track. 2. The photochromic optical disk has a photochromic layer which becomes a color developing body in response to a light spot of a first wavelength and becomes a decoloring body in response to a light spot of a second wavelength, and the reading means comprises the first reading means. The information signal is read and erased by a light spot of two wavelengths (or the first wavelength), and the writing means writes the information signal supplied by the light spot of the first wavelength (or the second wavelength). The rewritable photochromic optical disk reproducing apparatus according to claim 1, wherein the rewritable photochromic optical disk reproducing apparatus writes on an optical disk.