JPH1040565A - Optical disk drive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve operation efficiency, prolong a life of a laser diode and improve reliability, by sampling a track by a preceding sub beam, and controlling an output of a laser light so that the amount of a main beam becomes optimum in a three-beam type optical disk drive. SOLUTION: A state information on a track accessed by a sub beam preceding by one cycle to a main beam among three beams is detected by a photodetecting element 11. A condition whether the track at the position is dirty is judged from the amount of the detected light. A current for supplying the amount of the main beam from a driver 13 of a laser diode LD to a laser diode LD 14 in accordance with an output of the photodetecting element 11 corresponding to the sub beam is controlled thereby to adjust a laser output to be an optimum value. In this manner, the amount of the main beam reaching the track sampled by the sub beam can be optimum, whereby an optical disk is recorded, reproduced well without being influenced by the dust and dirt of the optical disk.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk drive such as a CD-R drive and a CD-E drive, and a file drive such as a CD-ROM drive and an MO disk drive. The present invention relates to an output control of a laser diode in an optical disk drive or a file driving device which can obtain an optimal amount of laser light at an actual access position on an optical disk.

[0002]

2. Description of the Related Art Conventionally, an optical disk drive of a three-beam system has been known (for example, Japanese Patent Laid-Open No. 7-192306).
No.). In this three-beam type optical disk drive, a hologram element is arranged between a laser light source and an information recording medium such as an optical disk or a magneto-optical disk, and one laser beam is converted into three beams having a track interval on the information recording medium. The beam is split and each beam is controlled independently. Accordingly, information on three tracks can be read at the same time, and the reading efficiency is improved.

[0003]

As described in the prior art, a three-beam type optical disk drive has been conventionally known, and an efficient reading operation can be performed by simultaneous reading of three beams. Become. However, in this conventional three-beam type optical disk drive, each beam is only used independently for tracking servo and signal detection. By the way, in the case of an information recording medium such as an optical disk or a magneto-optical disk (hereinafter collectively referred to as an optical disk), if a dirt such as dust or a fingerprint is present on the surface, a predetermined laser beam With the quantity of light, there is a problem that accurate reading and writing cannot be performed.

FIG. 7 is a top view for explaining the state of dirt attached to the entire optical disk. In the figure, 1 indicates an optical disk and 2 indicates a dirty portion.

[0007] As shown in FIG. 7, it is assumed that, for example, a contaminated portion 2 which is so remarkably impossible to be written has adhered to the optical disc 1 over a wide range on the order of several mm. If writing is performed in such a state, a writing error will occur. However, even in this case, if the laser beam power is controlled and driven with the write power, the high power level The drive current will continue to flow. Laser diodes generally have a shorter life depending on current and temperature.
If such a useless operation is performed, the laser diode will be deteriorated and the replacement time will be shortened, resulting in an inconvenience of increasing the cost.

According to the present invention, dirt or the like adhering to the surface of an optical disk is detected, and the output of the laser light is controlled so that the amount of the laser light becomes an optimum value according to the state of the actual recording position. It is another object of the present invention to suppress deterioration due to useless driving of a laser diode and improve the reliability of an optical disk drive.

[0007]

According to the first aspect of the present invention, an optical disk is accessed in an apparatus having a function of recording, reproducing, erasing, initializing, etc. information by focusing a laser beam on a recording layer of the optical disk. Beam splitting means for splitting a laser beam into three at the position of the recording layer of the optical disc at an integral multiple of the track, and a laser beam preceding the main beam among the three split beams Sampling means for sampling the state of the track using the signal of the sub-beam, and when the main beam reaches the track position sampled by the preceding sub-beam, the laser beam is emitted so that the light amount of the main beam becomes an optimum value. Controlling output.

According to a second aspect of the present invention, in the optical disk drive of the first aspect, the optical disk is a rewritable disk. When recording information, information of an area of the optical disk is obtained in advance by a preceding sub-beam and recorded. By changing the light amount of the main beam at the time of recording between the recorded area and the unrecorded area, the output of the laser beam is controlled so as to be an optimum value in each area.

According to a third aspect of the present invention, in the optical disk drive of the first or second aspect, a sum signal of a sub beam preceding the main beam and a sum signal of a sub beam following the main beam are compared. If the sum signal of the two sub-beams exceeds a predetermined value, it is determined that recording is not possible, and if the state lasts for a certain period of time, the recording position is determined by the main beam. At the time of recording, the output control of the laser beam is stopped to perform the constant current drive.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION

First Embodiment This first embodiment mainly corresponds to the invention of claim 1, but also relates to the inventions of claims 2 and 3, and the invention of claim 1 This is a basic invention. The present invention
The point that the laser light is divided into three parts is similar to that of the conventional three-beam type optical disk drive, but the three beams are divided into a sub-beam preceding the main beam, a main beam, and a sub-beam following the main beam. They are distinguished and assigned different functions. And
In the first embodiment, two beams, a sub beam and a main beam, which precede the main beam among the three beams, are used to precede information recording or reproduction by the main beam in advance. It is characterized in that the state of the processing target location (access position) is detected by the sub-beam, and when the main beam reaches the processing target location, the light quantity control is performed so that the light quantity becomes the optimum value. ing. First, the relationship between the position of the spot formed by the three divided beams and the track on the optical disk will be described.

FIG. 2 is a partially enlarged view for explaining the relationship between the position of a track on an optical disk and the position of a spot formed by three beams and the appearance of dirt on the optical disk surface in the optical disk drive of the present invention. In the figure,
Reference numeral 3 denotes a track (land), 4 denotes a groove, 5 denotes a spot by a preceding sub beam, 6 denotes a spot by a main beam, 7 denotes a spot by a succeeding sub beam, and 8 denotes a stained area.

As shown in FIG. 2, a spot formed by three beams, that is, a spot 5 formed by a preceding sub beam, a spot 6 formed by a main beam,
A total of three spots, that is, spots 7 by the following sub-beams, are focused on the track (land) 3. In this case, the interval between the three spots 5, 6, 7 (the pitch in the radial direction of the optical disk) is set to match the pitch of the track 3. Usually, when accessing the optical disc, the inner position is used as the home position, and recording and reproduction are performed toward the outer position. Therefore, when viewed from the main beam (spot 6), the sub beam (spot 5) on the outer position is used.
Is advanced by about one turn of the optical disk, and the sub-beam (spot 7) on the inner circumference side is delayed by about one turn of the optical disk. Therefore, a certain location (access position) on the track 3 where the preceding sub-beam has passed will be accessed by the main beam after the optical disc has rotated about one turn, so that the preceding position before the main beam accesses will be reached. When the sub-beam passes, the actual state of the place can be detected in advance.

More specifically, it is possible to obtain in advance information about the actual state (state of dirt or the like) of an arbitrary position on the optical disk by using the preceding sub-beam,
If the light amount of the main beam is controlled to an optimum value based on the information, the reliability of information recording / reproduction can be improved. For example, dirt or the like (dirt area 8 in FIG. 2) that has adhered over time changes in an analog manner, so how much the power (light amount) of the laser beam should be set depends on whether the sub-beam actually It is possible to set the optimal value from the state at the time of accessing by experiment or experience. Therefore, if the light amount of the main beam at the time when the optical disk rotates about one turn thereafter is controlled based on the information of the location (access position) detected by the preceding sub-beam, the optimum value can be set. In FIG. 2, the case where the interval between the spots of the three beams coincides with the track pitch has been described, but it is apparent that the same operation and effect can be obtained even if the interval is set to an integral multiple of the track pitch. Next, the configuration of the main part of the optical disk drive that performs such an operation will be described.

FIG. 1 is a functional block diagram showing an example of a main configuration of the optical disk drive according to the first embodiment of the present invention. In the figure, 11 denotes a light receiving element (photodetector), 12 denotes a power table, 13 denotes an LD (laser diode) driver, 14 denotes an LD (laser diode), and 15 denotes an optical path.

FIG. 1 shows three light beams emitted from the LD 14.
The main parts involved in the light amount control of the three beams, particularly, the respective parts for controlling the output of the laser beam so that the light amount of the main beam becomes an optimum value are shown. Specifically, LD1
The laser light emitted from 4 is reflected by the optical disk at a portion schematically shown as an optical path 15, and a part of the light enters the light receiving element 11. And this light receiving element 11
Is converted into an electrical signal. The light receiving element 11 corresponds to each of the three divided beams, that is, the sub beam preceding the main beam, the main beam, and the sub beam following the main beam, as shown in FIG.
In the first embodiment, the light receiving element 11 corresponding to the sub beam preceding the main beam is provided.
From the amount of received light detected by the above, the state of contamination at the location (access position) or the like is determined, and the optimal value is determined by controlling the amount of light of the main beam for performing recording and reproduction. In this case, the power table 12 in FIG. 1 is referred to.

FIG. 3 shows the power table 12 shown in FIG.
FIG. 7 is a diagram showing an example of the content of the sub-beam, and the amount of received sub-beams and LD
6 is a graph of a power table showing a relationship with (laser diode) power. The horizontal axis in the figure is the output of the light receiving element 11 (input of the power table), and the vertical axis is the LD driver 13.
(Power table output).

As shown in FIG. 3, when the output of the light receiving element corresponding to the preceding sub-beam is large, the current supplied from the LD driver 13 to the LD 14 is reduced, and when the output of the light receiving element is small, on the contrary, By increasing the current supplied from the LD driver 13 to the LD 14,
Stable writing (recording) and reading (reproduction) become possible. As described above, in the first embodiment, the laser beam is divided into three at the recording layer position of the optical disc so as to have an interval of an integral multiple of the track, and the signal of the sub beam preceding the main beam is used. Then, the state of the track is sampled, and when the main beam has just reached the track where the sub-beam has been sampled, the output of the laser beam is controlled so that the light amount of the main beam becomes an optimum value. Therefore, it is possible to emit the optimum amount of laser light (at the actual recording timing) to the actual access position where writing is performed by the main beam, and the recording is not affected by dirt or fingerprints on the optical disk. (The same applies to reproduction). In other words, an optical disk drive having high reliability of recorded information and reproduced information can be obtained.

Second Embodiment The second embodiment corresponds to the second aspect of the invention, but also relates to the first and third aspects of the invention. In the first embodiment, a case has been described in which the state of a location (access position) to be recorded is detected in advance by the preceding sub-beam, and the amount of laser light at the time of recording by the main beam is controlled to an optimum value. . The second embodiment also has a common feature that the state of a location (access position) to be recorded is detected in advance by the preceding sub-beam, but in the case of an information rewritable disc, the access position becomes dirty. Instead of detecting such a state, it is characterized by detecting whether the area is a recorded area or an unrecorded area.

When recording information on a rewritable disk, there are cases where writing is newly performed and cases where writing is performed at a location where data has already been recorded. The optimum power of the laser beam is different between the case where writing is performed on a new (unrecorded area) and the case where writing is performed on an already recorded location (recorded area). Therefore, before performing recording by the main beam using the preceding sub-beam, it is checked whether or not the recording location is already recorded, and the main beam at the time of recording is determined depending on whether the recording is performed or not. To set the optimum value.

FIG. 4 is a partially enlarged view for explaining the relationship between the track position on the optical disk and the spot position by three beams and the state of the recorded bits in the optical disk drive of the present invention. The reference numerals in the figure are the same as those in FIG. 2, and 9 indicates a recorded bit.

FIG. 4 corresponds to FIG. 2 described above. A spot (access position) on the track 3 has been recorded by the spot 5 by the preceding sub-beam (whether or not the recorded bit 9 has been recorded). Is determined, and in accordance with the determination result, when the main beam (spot 6) is accessed after the optical disk has rotated about one round, the light amount is controlled to an optimum value. Other operations are the same as those in the first embodiment.

FIG. 5 is a functional block diagram showing an example of the configuration of the main part of the optical disk drive according to the second embodiment of the present invention. The reference numerals in the figure are the same as those in FIG. 1, and 16 indicates a light table.

In the optical disk drive shown in FIG. 5, the light receiving element 11 of the optical disk drive shown in FIG.
A light table 16 is added to the D driver 13. The light table 16 holds the optimum power of the laser light at the time of recording on the recorded area and the optimum power of the laser light at the time of recording on the unrecorded area. Although it depends on the characteristics of the optical disk, in general, in the case of a recorded place, the reflectance is higher than that of the unrecorded part, so whether or not the recorded place is determined by the detection output of the light receiving element corresponding to the preceding sub beam. It can be determined accurately. In order to compensate for the power corresponding to the difference between the recorded area and the unrecorded area based on the information on whether or not the information has been recorded, a write table 16 is added separately from an additional portion due to dirt or the like (information of the power table 12). Thus, a more suitable current value is determined and LD
14 can be driven. As described above, in the second embodiment, the laser beam is divided into three at the position of the recording layer of the optical disc so as to have an integral multiple of the track, and the signal of the sub beam preceding the main beam is used. Then, it is determined whether the area is a recorded area or an unrecorded area, and the output of the laser beam is controlled so as to have an optimum value in each area by changing the light amount of the main beam at the time of recording. Therefore, in addition to the effects of the first embodiment, even when newly recording information or when overwriting (writing at a recorded location), recording that is not affected by dust or fingerprints on the optical disc. Can be performed.

Third Embodiment The third embodiment corresponds to the third aspect of the present invention, but also relates to the first and second aspects of the present invention. In the first embodiment, before the main beam is used to record or reproduce information by using two beams, a sub beam and a main beam, which precede the main beam, a process target is preliminarily processed by the preceding sub beam. A case has been described in which the state of the location (access position) is detected, and when the main beam reaches the location to be processed, the light quantity control is performed so that the light quantity becomes an optimum value.

However, as shown in FIG. 7, the optical disk 1 has a dirty portion 2, and when the range of the dirty portion 2 is wide, recording is not possible. However, in the first embodiment, even in such a case, a drive current is continuously supplied to the LD 14 while referring to the power table 12 in order to emit an optimal laser beam.
As described in connection with the related art, the life of the LD 14 is generally shortened depending on the current and the temperature. Therefore, if such an unnecessary operation is performed, the LD 14 is deteriorated and the replacement time is advanced. In the third embodiment, not only the presence / absence of dirt due to the preceding sub-beam, but also the degree of the dirt is determined, and for an extremely dirty part, the LD1 is determined by the optimum recording power.
4 is stopped and steady driving with low power is performed.

FIG. 6 is a functional block diagram showing an example of the configuration of the main part of the optical disk drive according to the third embodiment of the present invention. The reference numerals in the figure are the same as those in FIG. 1; 17 is a time monitoring unit; and 18 is a power control signal output unit.

In the optical disk drive shown in FIG. 6, the power table 1 of the optical disk drive shown in FIG.
2, a time monitoring unit 7 is added. The time monitoring unit 7 monitors the time when the difference between the output level of the light receiving element corresponding to the preceding sub beam and the output level of the light receiving element corresponding to the succeeding sub beam exceeds a predetermined value. More specifically, a sum signal of a sub beam preceding the main beam and a sum signal of a sub beam following the main beam are compared, and a difference between these two sum signals indicates a predetermined magnitude. Measure the time exceeded. The time set in this case differs depending on the number of rotations of the optical disk at the time of access.
If it lasts for more than the time corresponding to, the place is determined to be a place where recording is practically impossible. For example, as shown in FIG. 7, when the dirty portion 2 on the optical disc 1 is wide (the degree of dirt is remarkable), three tracks adjacent to each other (or at an interval of an integral multiple thereof) are located at both ends. There is a difference in the light receiving output between the preceding sub beam and the following sub beam. Therefore, when such a state continues for a certain period of time or longer, the drive current of the LD 14 is unilaterally suppressed to prevent the consumption of the LD 14 irrespective of the preset recording power (contents of the power table 12). .

[0028]

According to the optical disk drive of the present invention, the laser beam is divided into three at the recording layer position of the optical disk so as to have an interval of an integral multiple of the track, and the signal of the sub beam preceding the main beam is used. When the main beam reaches the track where the sub-beam has just been sampled, the output of the laser beam is controlled so that the light amount of the main beam becomes an optimum value. Therefore, it is possible to emit the optimal amount of laser light to the actual access position of the optical disk,
Since recording can be performed without being affected by dust or fingerprints on the optical disk, a highly reliable optical disk drive can be obtained.

According to a second aspect of the present invention, in the optical disk drive of the first aspect, at the time of recording information on the rewritable optical disk, information of the optical disk is obtained in advance by a preceding sub-beam, and the recorded area and the unrecorded area are recorded. The output of the laser beam is controlled so as to be optimal in each area by changing the light amount of the main beam at the time of recording. Therefore, in addition to the effect of the optical disk drive according to the first aspect, it is possible to perform recording without being affected by dust and fingerprints on the optical disk, even when recording new information or overwriting information. A high optical disk drive is obtained.

In the optical disk drive according to the third aspect, in the optical disk drive according to the first or second aspect, if the sum signal of the sub beam preceding the main beam and the sub beam following the main beam is significantly different, recording is performed. If it is determined that the state is impossible, and if this state continues for a predetermined time or more, the constant current drive is used instead of controlling the output of the laser beam when recording at the position by the main beam. Therefore, in addition to the effect of the optical disk drive according to claim 1 or 2, it is possible to provide an optimum amount of laser light to the actual access position of the optical disk, and the optical disk is not affected by dirt such as dust and fingerprints. It is possible to obtain an optical disk drive that can perform recording and does not adversely affect the life of the laser diode even when recording on an optical disk in which there is a significant degree of dirt or the like that cannot be partially recorded.

[Brief description of the drawings]

FIG. 1 shows an optical disk drive according to a first embodiment of the present invention.
It is a functional block diagram showing an example of an important section composition in an embodiment.

FIG. 2 is a partially enlarged view illustrating a relationship between a track position on an optical disk and a spot position by three beams in the optical disk drive of the present invention, and a stain on the optical disk surface.

FIG. 3 is a diagram showing an example of the contents of a power table 12 shown in FIG.

FIG. 4 is a partially enlarged view illustrating a relationship between a track position on an optical disk and a spot position by three beams, and a state of a recorded bit in the optical disk drive of the present invention.

FIG. 5 shows an optical disk drive according to a second embodiment of the present invention.
It is a functional block diagram showing an example of an important section composition in an embodiment.

FIG. 6 shows a third example of the optical disk drive of the present invention.
It is a functional block diagram showing an example of an important section composition in an embodiment.

FIG. 7 is a top view illustrating a state of dirt attached to the entire optical disc.

[Explanation of symbols]

 Reference Signs List 11 light receiving element 12 power table 13 LD driver 14 LD 15 optical path 16 light table

Claims (3)

[Claims] A drive device for accessing an optical disk in a device having a function of recording, reproducing, erasing, and initializing information by condensing a laser beam on a recording layer of the optical disk. A laser beam splitting means for splitting into three at intervals of the track at the position of the recording layer, and a track state using a signal of a sub-beam preceding a main beam among the three split beams. An optical disk drive, comprising: sampling means for sampling, wherein when a main beam reaches a track position sampled by a preceding sub-beam, an output of a laser beam is controlled so that a light amount of the main beam becomes an optimum value. . 2. The optical disk drive according to claim 1, wherein the optical disk is a rewritable disk, and when information is recorded, information of an area of the optical disk is acquired in advance by a preceding sub-beam, and the information is recorded on an optical disk. An optical disc drive characterized by controlling the output of a laser beam so that an optimum value is obtained in each area by changing the light amount of a main beam at the time of recording in an unrecorded area. 3. The optical disk drive according to claim 1, wherein a sum signal of a sub beam preceding the main beam,
A sum signal comparing unit that compares a sum signal with a subsequent sub beam with respect to the main beam; and when the sum signal with the two sub beams exceeds a predetermined value, it is determined that recording is not possible, When the state continues for a predetermined time or more, the optical disk drive stops laser beam output control and performs constant current driving when recording is performed at the recording position by the main beam.