JPH02306431A - Optical recording/reproducing device - Google Patents

Abstract

PURPOSE:To prevent a double writing mistake by using a means which irradiates a preformat part of the upstream side where the data are written to a recording medium with light via the write power and compares the reproduction signal produced by the return light of the preformat part with a prescribed level to decide whether a recording task is already finished or not. CONSTITUTION:A double write preventing means prevents a double writing mistake with the output which compared the waveheight value of the envelope of a reproduction signal of a preformat part 31 formed at the front of a data area with the prescribed level. At the part 31 and RF envelope 1 is set smaller than MON and this MON is set smaller than an RF envelope 2. Therefore the part 31 is irradiated again with the light via the write power if a data writing command is given to a data part after the data are once written to the part. Thus the identification signal received from a recorded state identifying circuit 11 is set at 'L' to show a double writing state. Then a controller 12 produces immediately a command to inhibit the data writing operations using the write power and to prevent the double writing mistake for the data part.

Description

DETAILED DESCRIPTION OF THE INVENTION rlLl Industrial Field] The present invention relates to an optical recording/reproducing device provided with means for preventing double writing.

[Prior art and problems to be solved by the invention] In recent years, information has been recorded at high density on a recording medium by irradiating a light beam, and information recorded at high density on a recording medium is reproduced at high speed. 2. Description of the Related Art Optical recording and reproducing apparatuses capable of recording and reproducing data are attracting attention.

In the above device, for high-density recording, recording or reproducing
When recording, it is necessary to narrow down the light beam to a sufficiently small size. Therefore, in addition to controlling the focusing of the objective lens that focuses the light beam on the recording medium, recording is performed while tracking control is being performed to track the light beam to the current track. and playback.

By the way, some recording media utilize phase transformation.

When reading optical discs that utilize this phase transformation, since the optical power is at a low level, the optical disc remains in an amorphous state and has a low reflectance (or a low amount of reflected light), but that part cannot be read. When irradiated with high-power light, the amorphous state transforms into a crystalline state,
Reflectance increases. Therefore, it is now possible to record binary information using this difference in the level of reflected light.

The optical disc using the above-mentioned phase transformation is a write-once type, and even in this case, 1. If writing has just been performed, it is necessary to prevent double writing or overwriting.

Therefore, the applicant of this case
1l1 proposes a means to prevent double writing. That is, in this proposal, a record mark section is provided in front of the data section of the recording track, a record mark is written on the record mark section by DC light emission before data is recorded, and the amount of light reflected from the record mark section is monitored. When the second DC light emission is performed on the record mark portion due to double writing, the amount of light reflected from the record mark portion increases. Therefore, double writing can be prevented by monitoring the amount of reflected light from the record mark portion using a predetermined threshold value. In addition, the front part of the record mark part is an area formed by a phase structure (pit) during manufacturing, and shows the sector mark part indicating the start of the sector, the track address, the sector address, etc. A preformat section consisting of an ID section is formed.

By the way, the recording surface of an optical disc has variations in reflectance. Further, the reflectance of each part will be different due to dirt on the recording surface or dust in the base material.

FIG. 6 is an explanatory diagram showing changes in the amount of reflected light from a formatted ID section and a record mark section when the reflectance of the recording surface is not constant. The broken line indicates an optical disc with a low reflectance, and the solid line indicates a reflective indicates an optical disc with a high rate.

Now, for optical discs with low reflectance shown by the broken line,
In the - mark area, the level of the amount of reflected light increases to 8 in the figure by the first writing, and the level of the amount of reflected light increases to B in the figure by the second writing. Therefore, for example, by setting the threshold value (slice level) to level C in the figure and detecting whether the level of the amount of reflected light in the record mark area exceeds this threshold value, it is possible to determine whether data has already been written in the data area. It is possible to judge whether or not the data has been written, and double writing can be prevented.

On the other hand, the solid line has a higher reflectance than the dashed example - and
This shows an optical disc in which the reflectance changes between the front side and the rear side of the ID part, and in this case, the level of the amount of reflected light increases to D higher than the slice level C by the first writing of the record mark part, Further, by the second writing, the amount of reflected light increases to E in the figure. Therefore, in this case, it is necessary to set the slice level to F in the figure, for example.

As described above, in conventional optical recording and reproducing devices, the reflectance is not constant due to variations in optical discs during manufacturing, scratches on the recording surface, dust in the base material, etc., so at a fixed threshold level, There was a problem in that it was not possible to reliably detect whether or not there was double writing.

The present invention has been made in view of such problems, and includes:
It is an object of the present invention to provide an optical recording/reproducing device '4A that can reliably prevent double writing regardless of the difference in reflectance of optical discs.

[Means and effects for solving the problem] In the present invention, when the pre-7 format section provided upstream of the data area is reproduced, the wave value of the envelope of this reproduced signal is determined based on the monitor output level of the laser power, etc. By providing double writing prevention means that compares the set predetermined level with the comparison means and outputs a signal to prohibit writing if the comparison output exceeds the predetermined level, regardless of the difference in reflectance of the recording surface. , to prevent double writing.

[Example] Hereinafter, the present invention will be specifically described with reference to the drawings.

1 to 5 relate to an embodiment of the present invention, FIG. 1 is a schematic configuration diagram of the embodiment, FIG. 2 is an explanatory diagram showing the format of a recording track, and FIG. 3 is a recording stream detection circuit. FIGS. 4 and 5 are explanatory diagrams showing the setting conditions of the discrimination signal level in FIG.

As shown in FIG. 1, the optical recording/reproducing device 1 of the embodiment includes:
An optical pickup 3 is placed opposite a phase change optical disk 2 rotated by a spindle motor (not shown). The optical pickup 3 is movable in the radial direction of the phase change optical disk (hereinafter simply referred to as an optical disk) 2, that is, in the direction R across concentric or spiral tracks, by a coarse movement means such as a VCM. be.

The optical pickup 3 optically performs recording or reproduction on the optical disc 2 using a light beam output from a laser diode 4. The laser diode 4 includes, for example, a monitor bin photodiode 5 and the like, which are integrally sealed together with the laser diode 4 in the same housing 6.

The laser diode 4 outputs the back light to the monitor photodiode 5, while the front light is used for recording or reproduction. The photodiode 5 that receives this backlight converts the photocurrent corresponding to the backlight into an APC.
The output of the APC circuit 7 is used to automatically control the light emission output of the laser diode 4 to a proper value.

By the way, the photodetector 8 that receives the return light reflected by the optical disc 2 is formed of, for example, a four-divided light receiving element, and the RF low signal as a reproduced signal is generated by the addition output of these light receiving elements through an adder/subtractor circuit 9. be done. This RF signal is input to the RF envelope circuit 29 of the recorded identification circuit 11 via a coupling capacitor 27 that blocks direct current.

RF 1 envelope circuit 29 detects the RF low signal envelope and provides the RF envelope signal to the inverting end of comparator 28. On the other hand, the monitor signal of the photodiode 5 is input to the non-inverting terminal of the comparator 28 . The output signal (identification signal) of this recorded identification circuit 11 is
When the identification signal is, for example, L'', the controller 12 controls the APC circuit 7 to regulate the current supplied to the laser diode 4 and prohibits it from reaching the light emission level. (maintained at read power).

By the way, the optical pickup 3 has the following configuration, for example.

For example, a P-polarized light beam from the laser diode 4 is collimated by a collimator lens 14 and input to a polarizing beam splitter 15 . The light beam that has passed through the polarizing beam splitter 15 at almost 100% is circularly polarized by the quarter-wave plate 16, and then condensed by the objective lens 17 and irradiated onto the optical disk 2. This optical disc 2
1=The light passes through the objective lens 17 and the quarter-wave plate 16, becomes S-polarized light, is almost 100% reflected by the polarizing beam splitter 15, and enters the critical angle prism 18. The light reflected by the slope of the critical angle prism 18 is received by the photodetector 8 placed in the far field position. The output signal of the photodetector 8 is input to an adder/subtracter circuit 9, and the adder circuits 21, 22, and 23 generate an RF low signal as a reproduced signal. Also, for example, the tightening circuit 21
．． A tracking error signal TER is generated by 22 and a subtraction circuit 24, and a tracking servo system is formed by applying this signal TER to a tracking coil 26 forming a lens actuator via a tracking servo system path 25. . Note that by changing the combination of light-receiving elements to be subtracted, a focus error signal is generated by the critical angle method (as shown in the diagram).

By the way, when the recorded identification circuit 11 scans the track with the optical beam l\, when comparing the RF envelope signal and the monitor signal for the preformatsu 8 section 31 in the format for the track as shown in FIG. This preformatsu 8
It is detected whether the data section (data area section) on the downstream side of the section 31 is recorded or unrecorded.

Note that in the format shown in Figure 2, each track is divided into multiple sectors, and each sector has a sector mark (
SM), followed by I where the sector identification index is recorded.
A section D is formed. A VFO section and a data section are formed next to the 10th section.

The preformat section 31 is coated with an amorphous material and has a topological structure having an uneven shape, and is formed upstream of the data section within the same sector. The FO section is an area provided for synchronizing the data synchronizer (where data sent asynchronously from the disk is synchronized with the clock on the controller side), and 2-7 COdeF, 100100...・・・
It is written in the pattern of ・.

The data synchronizer is designed to synchronize with the pattern written in the VFO section in advance. With respect to the data section that follows this VFO section, the data in this data section is synchronized in the VFO section, so that the data can be read in correct synchronization.

When recording data in an unrecorded data section, the preformat section 31 irradiates the preformat section 31 with write power, and then writes data into the data section. By irradiating with this write power, the preformat part 31 undergoes a phase transformation from an amorphous state to a crystallized state, and a low oxide Te 02 of tellurium oxide is formed.
For materials such as the above, the reflectance will increase.

By the way, since the light irradiation time with this light power is very short, even the portion irradiated with light does not completely change from an amorphous state to a crystalline state. Therefore, when the light is irradiated again with the light power, the remaining amorphous state changes to a crystalline state, and the reflectance further increases. That is, if the light is irradiated once with the light power and then the light is irradiated with the light power again, the amount of reflected light increases. However, since the ID portion has a phase structure as described above, even if the reflectance of the pit portion increases, the amount of reflected light from the pit portion does not increase. In other words, when light is irradiated onto the Il) portion, the amount of reflected light from the portion other than the pit portion increases, and the difference in the amount of reflected light between the pit portion and the portion other than the pit portion increases. That is, the amplitude (peak value) of the RF low signal envelope becomes larger.

In this embodiment, by utilizing this feature, the recorded identification circuit 11
The monitor signal and BRIFOMATSU 8 part 31 are
-The relationship with the RF envelope signal in the case of light irradiation with power is set as shown in FIG.

In other words, if the peak value of the RF envelope signal once irradiated with light is expressed as RF envelope (1), the preformat unit 31 sets this RF envelope (1) to be smaller than the signal level MON of the monitor signal. It is set to . In other words, RF envelope (1)<MON. Further, the signal level MON of the monitor signal is set smaller than the RF low signal peak value RF envelope (2) when light is irradiated with twice the write power. Therefore, the RF envelope (1) <
Set MON<RFI envelope (2).

Therefore, once data has been written to the data section, if a command is issued to write data to this data section again, the preformat section 31 is irradiated with light with the write power again, so that the preformat section 31 is irradiated with light again by the write power. The identification signal is ′
L'', indicating double writing. As a result, the controller 12 immediately issues a command to prohibit data writing using write power, thereby making it possible to prevent double writing to the data section.

Next, the operation of the optical recording/reproducing apparatus constructed in this way will be explained with reference to the waveforms shown in FIGS. 3 to 5.

Now, assume that data is to be recorded in the data section.

In this case, light with a write power is emitted from the optical pickup 3, and first, the ID section is irradiated with DC light before the data section is taken in and out. As a result, the ID portion undergoes a phase transformation from an amorphous state to a crystalline state. Also, 10
The return light from the optical pickup 3 is received by the photodetector 8 via the optical pickup 3. Each light receiving element of the photodetector 8 outputs a level signal based on the amount of reflected light to the addition/subtraction circuit 9 J-
Ru.

The addition/subtraction circuit 9 generates and outputs an RF low signal based on the sum of the signals from each light receiving element. RF low signal, coupled capacitor +J
27 to the recorded identification circuit 11, and is subjected to envelope detection in the RF envelope circuit 29.

By being inputted via the coupling capacitor 27 and subjected to envelope detection, the low frequency component of the RF low signal is removed, and the RF low signal envelope (peak value) is output from the RF U'' envelope circuit 29. That is, RF
The envelope circuit 29 outputs an RF envelope signal at a level based on the RF multiplied signal peak value, regardless of the difference in reflectance of each part of the optical disc.

The comparator 28 compares the level of this RF envelope signal with the level of a monitor signal based on the amount of light irradiated onto the optical disc 2.

When each track of the optical disc 2 has a format as shown in FIG. 2, the RF envelope signal and monitor signal change as shown in FIG. 4 during the first write mode. That is, in this case, since the RF envelope [1-p(1)<MON], the comparator 28 outputs an identification signal of If HII to the controller 12. Based on this identification signal, the controller 12 determines that data has not yet been written to the data section, and writes to the data section with write power.

Next, when a command to record data is erroneously issued to the data section in which data has been written once, the ID section is irradiated with light again at the write power. This promotes crystallization of the ID portion. Since the pill forming portion of the ID portion has a phase structure, the amount of reflected light hardly changes, and the amount of reflected light increases in the ID portion other than the pit forming portion. The photodetector 8 receives the return light from this ID section, and the addition/subtraction circuit 9 outputs an RF multiplied signal. Therefore, I
The amplitude of the RF signal due to the returned light from the D section increases significantly.

As a result, the output of the RF envelope circuit 29 becomes the fifth
As shown in the figure, the level MON becomes higher than the level MON of the monitor signal. Then, the comparator 28 outputs an L II identification signal to the controller 12. As a result, ]
The controller 2 immediately outputs a command to prohibit writing in the data section to the ΔPC circuit 7, and maintains the current flowing through the laser diode 4 at read power. Therefore, it is possible to prevent double writing to the data section at the rear position within the same sector as the printer 7t-mat section 31.

In this way, in this embodiment, the RF envelope circuit 29 uses the return light from the preformat section 31 to
Since the signal is input via the double signal coupling capacitor 27 and envelope detection is performed, low frequency components of the RF double signal are removed. In addition, by irradiating the ID part of the phase structure with light at a light power, the RF signal peak value increases, so the R
From the output of the F envelope circuit 29, it can be determined that the ID section has been irradiated with light for the second time.

In other words, even if the reflectance of the recording surface of the optical disc is not constant at the position J:, the preformat section 31 upstream of each data section
By determining whether the amount of reflected light exceeds the reference level, it is possible to determine whether the downstream data section has been recorded. Therefore, even if a recording command is issued by mistake, it is possible to prevent double writing in the recorded data section.

In addition, according to this embodiment, it is possible to prevent erroneous double writing at the time of a write command. Before the p1 write operation, the data section is scanned in read mode, and the data is determined from the signal level. Since it is not necessary to check whether the copy has already been recorded, the write operation can be completed in a short time.

Furthermore, it is possible to cope with the case where the optimum conditions for determining whether an inner track, an outer track, and C1 recording/unrecording may deviate from the embodiment.

Further, even if there are variations in the optical discs 2 used, the variations may be corrected by variable setting of the amplification factor.

Note that it is possible to determine whether or not the recording has been completed in synchronization only with the period of the RF envelope signal when it is reflected by the preformat section 31. However, if the "l L II" output signal is output not only during this period but also during that sector period, recording within that sector may be prohibited.

Note that when "L" is detected, the notification means may be configured to notify that it is a double write or overwrite command.

Note that the present invention is not limited to the optical pickup 3 having the configuration shown in FIG. Furthermore, the monitor signal is not limited to the one that uses the back light, but may also use a part of the front light.

Furthermore, in the above embodiment, the reflectance increases due to phase transformation, but the reflectance increases due to phase transformation.
It is clear that the present invention can be easily applied also to cases where the light intensity (or reflected light end) is low. Furthermore, it is possible to indicate that the data section has already been recorded without providing a record mark section, and the recording density can be improved.

[Effects of the Invention] As explained above, according to the present invention, light is irradiated with write power to the preformat section on the upstream side where data is written to a phase-transforming recording medium, and the return light of this preformat section is Since the reproduction signal is compared with a predetermined level to determine whether or not it has been recorded, it is possible to prevent erroneous overwriting of the recorded data section.

[Brief explanation of drawings]

1 to 5 relate to an embodiment of the present invention, FIG. 1 is a schematic configuration diagram of the embodiment, FIG. 2 is an explanatory diagram without showing the format of the recording track, and FIG. 3 is a recorded detection FIG. 4 and FIG. 5 are explanatory diagrams showing the setting conditions of the discrimination signal level applied to the circuit, FIGS. 4 and 5 are explanatory diagrams of the operation of the embodiment, and FIG. be. DESCRIPTION OF SYMBOLS 1... Optical recording/reproducing device, 2... (phase change) optical disc, 3... Optical pickup, 4... Laser diode, 5... Pin-type A-to-Die A-de, 8... Photodetector, 1
1... Recorded identification circuit, 12... Controller, 2
7...Coupling capacitor, 28...Comparator, 29...
・RF envelope circuit.

Claims (1)

[Claims] In a phase change type optical recording/reproducing device, in order to prevent the data area that has been written once from being written again, when a write command is issued, a preformat section provided before the data area is used. What is claimed is: 1. An optical recording and reproducing device comprising double writing prevention means for preventing writing at an output in which the peak value of an envelope of a reproduced signal is compared with a predetermined level.