JPH11259870A - Disk recording medium reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To read data always at the read speed of the highest performance according to the individual differences of disk recording media. SOLUTION: This reproducing device drives and rotates a disk recording medium 201 where data are recorded at an equal linear speed at an equal angular velocity to perform reproduction in accordance with a characteristic reproduction speed varying linearly along the radius direction, divides the information recording surface of the disk recording medium 201 into plural areas in the radial direction, calculates as an access failure rate the ratio of an access failure frequency occupied to an access frequency when the divided areas are accessed and varies the said angular velocity when the access failure rate exceeds a previously set threshold to vary the characteristic reproduction speed in the said area to a lower speed. Consequently, the disk recording medium 201 can be reproduced with the highest performance matching the medium quality.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disc-shaped recording medium reproducing apparatus capable of always reading data at a reading speed of the highest performance according to individual differences of the disc-shaped recording medium.

[0002]

2. Description of the Related Art FIG. 5 is a circuit diagram showing an example of a conventional optical disk reproducing apparatus. The optical disc reproducing apparatus 200 shown in FIG. 1 is a disc-shaped recording medium 20 such as a CD-ROM.
1 is rotated by a medium rotating motor 202, and an optical pickup 203 for irradiating a laser beam is
And supplies the read optical information to the CD signal processing circuit 204. CD signal processing circuit 204
Is supplied with a control command from the control CPU 205 and an analog signal from the optical pickup 203.
The information spirally recorded in the optical pickup 203
Controls the driver 208 so that
The optical pickup 203 converts an analog signal read by the optical pickup 203 into digital data, acquires address information recorded on the recording medium 201, and sends the converted digital data to the CD-ROM signal processing circuit 206.
The CD-ROM signal processing circuit 206 decodes the digital signal sent from the CD signal processing circuit 204 by using an error correction method or the like, and supplies the decoded signal to the HOST I / F 207. The HOST I / F 207 transmits data to a HOST device (not shown) such as a host computer on the I / F to which the optical disc reproducing device 200 is connected,
For example, receiving a command from the HOST device.

[0003] Data is recorded on a recording medium 201 by a constant linear velocity recording method so that a linear velocity is constant with respect to a spiral track. For this reason, when the recording medium 201 is rotated at a constant rotational speed, that is, when the angular velocity is reproduced, when the optical pickup 203 is on the outer peripheral side, the speed at which information is read is when the optical pickup 203 is on the inner peripheral side. Several times faster than the speed of reading information. Normally, the CD signal processing circuit 204 issues a command to the driver 208 according to the scanning position of the optical pickup 203 so that the speed at which information is read from the recording medium 201, that is, the reproduction speed is constant regardless of the position of the optical pickup 203. , The number of rotations of the medium rotation motor 202 is controlled.

In general, the reading speed (reproduction speed) is preset to a predetermined value as a value unique to the apparatus, and is defined by how many times the reading speed (reproduction speed) of an audio compact disc corresponds to the reading speed. However, in the case of the linear velocity reproduction, the difference between the rotation speed of the recording medium 201, that is, the angular velocity between the innermost peripheral reading and the outermost peripheral reading is about 2.5 times corresponding to the radial distance ratio of the reading position. Occurs. In the case of a so-called audio compact disc, the medium rotation speed is about 5 per second when reading the innermost circumference.
On the other hand, the rotation speed of the medium at the time of reading the outermost periphery is reduced to about 1 / 2.5, ie, about 200 rotations per second.
Also, with this kind of audio compact disc, if the playback speed is increased arbitrarily, the tempo of the music itself to be played will also increase, so increasing the playback speed does not make sense. In the case of a CD-ROM device used as a storage device, the higher the reproduction speed is, the faster the information can be read, so that the reproduction speed is a very important factor. Specifically, for example, the medium rotation motor 202 is always set at 4000 per second.
When playing at the same angle by rotating with rotation, digital data can be read at approximately eight times the speed (8 times speed) when reading the innermost circumference, and approximately 20 times (20 times speed) when reading the outermost circumference. ) Can read digital data. That is, as shown in FIG. 6, the reading speed (reproduction speed) increases as the reading position of the optical pickup 203 approaches the outer peripheral side, and the change is made linearly and smoothly.

On the recording surface of the recording medium 201, tracks having a width of 0.5 μm are arranged at intervals of 1.6 μm. However, it is not easy to control the optical pickup 203 to always follow the tracks. Absent. The signal read by the optical pickup 203 is a CD signal processing 204
The position of the optical pickup 203 is controlled through the driver 208 so that the optical pickup 203 can track the center of the track. The recording medium 201 is rotationally driven by a medium rotating motor 202. However, a track on the recording medium 201 is periodically shifted in the X direction in FIG. Focusing error may occur in the Y direction. For the optical pickup 203, tracking control or focusing control is applied in a direction to cancel the above-mentioned deviation so as to always track the track on the recording medium 201, but the target track cannot be canceled without completely canceling the control deviation. In some cases, it deviates. The boundary between whether such deviation is within the control range or not is determined by the amount of deviation and the amount of change per unit time of the deviation. It can be considered that the smaller the amount of shift and the smaller the amount of change per unit time, the easier it is to cancel. In the case of the above-described optical disk reproducing apparatus in which the medium rotating motor 202 is always rotated at 4000 revolutions per second and data is read at 8 to 20 times speed, the data reading environment becomes more severe when reading on the outer peripheral side.

Further, the weight balance of the recording medium 201 may be lost due to the user touching the surface of the recording medium 201 or the surface of the recording medium 201 may be damaged. When a recording medium having such an unbalanced weight is reproduced, the optical pickup 2
When the number 03 is in the outer circumferential direction, the shift amount (focusing error) in the Y direction of the recording medium exceeds the range that can be canceled, and the reading becomes impossible, or the reading operation is performed by setting the reproduction speed to a low speed again. You need to start over. Further, not only for such acquired reasons, but also for a recording medium in which the weight balance has been lost from the beginning of production, there is a high possibility that the same problem occurs. FIG. 7 is a diagram showing a reproduction area of an optical pickup capable of following a track on such a defective recording medium. In the figure, the limit reading position 203b of the optical pickup 203 capable of following a track is a recording medium 2 at a reproduction speed of 16 times.
01 indicates a position where the amount of deviation from the weight imbalance deviates from the range that can follow the track. That is, in the area B, if the reproduction speed is 16 times, the track can be sufficiently followed, but if the reproduction speed exceeds 16 times, the track cannot be followed. 203a is the innermost position of the optical pickup 203, and the area A is between 203a and 203b. Reference numeral 203c denotes the outermost peripheral position of the optical pickup 203, and a region B is between 203b and 203c.

A conventional technique for reproducing such a defective recording medium will be described below. First, consider a case where the optical pickup 203 is located in the area A shown in FIG. Data reading can be broadly divided into searching for a target address and reproducing data. Here, first, FIG.
The search for the target address will be described with reference to the flowchart shown in FIG.

The recording medium 201 is rotated at a rotational speed for providing a preset reproduction speed as a value unique to the above-described apparatus, for example, at approximately 4000 revolutions. It is assumed that the reproduction speed is double speed, and the reproduction speed is about 20 times when reading on the outer peripheral side. First, in step (1000) shown in FIG. 8, a timer is started. This is because, if the optical pickup 203 is unable to move for some reason while moving to the target position, the optical pickup 203 continues the moving operation without meaning.
This is to prevent a situation in which the optical disk reproducing apparatus becomes inoperable. When the address information of the current position of the optical pickup 203 is obtained in step (1010),
In the following step (1020), the difference from the target address is calculated, and in step (1030), the optical pickup 203 starts moving. This step (1030)
Then, the optical pickup 203 is moved by directly supplying a movement control signal from the control CPU 205 shown in FIG. 5 to the driver 208. If the movement amount is large, first, the optical pickup 203 is moved to the vicinity of the target address and then gradually. To the final destination address. Address information indicating the current scanning position during or after movement is obtained in step (1040).

In a determination step (1050) following the step (1040), it is determined whether or not the current address matches the target address. If the current address has reached the target destination, the flow advances to step (1080) to store the data. Start reading. On the other hand, if the target destination has not been reached, it is checked in step (1060) whether a time-out exceeding the time set in the timer has occurred. Proceed to 1020) to continuously move the optical pickup 203. However, if a timeout occurs,
It is determined that address information cannot be obtained at the current playback speed, and the playback speed is reduced in step (1070).
Start again from starting the timer. However, if the scanning position has already reached the area B, step (1040)
However, even if the optical pickup 203 attempts to acquire the address information after the movement of the pickup, the optical pickup 203 cannot correctly follow the track, and thus cannot acquire the correct address information. For this reason, in the determination step (1050), only the determination result that the vehicle has not reached the target destination is obtained, and steps (1020) to (1050) are repeated until a timeout occurs in step (1060). .

If it is determined in step (1060) that a timeout has occurred, the process proceeds to step (107).
At 0), the reproduction speed is reset to, for example, 8 times speed, and a series of steps is repeated. For example, the optical pickup 203 is located at the position 203b of the optical pickup shown in FIG.
Is issued, a command is issued to the medium rotation motor 202 to change the rotation speed to about 1600 rotations per second. However, in order to reduce the number of rotations of the medium rotation motor rotating at 4000 revolutions per second to 1600 revolutions per second,
A waiting time is required and it is not possible to proceed to the next step until it is confirmed that the rotation has dropped to 1600 rotations.

When the reproduction speed is changed to the 8 × speed and the process is executed again from step (1000), the optical pickup 203 does not change the track this time even if the displacement of the medium is large because the rotation speed of the medium is sufficiently low. Can follow. For this reason, the address information can be correctly acquired in step (1040).
After the steps 20) to (1050) are repeated several times, the robot reaches the target destination, and the data reading in step (1080) can be started.

[0012]

However, in the conventional optical disk reproducing apparatus 200, a timeout occurs until the search is completed, and a waiting time is required to reduce the number of rotations.
There is a problem that a considerable amount of time is required from the time when the data is issued from the device to the time when the data is actually sent. Further, in the optical disc reproducing apparatus 200 connected to the HOST apparatus, a search is frequently performed in accordance with data reading from the recording medium 203.
Therefore, even if the reproduction speed is once reduced to 8 × speed as described above, the area A can be sufficiently searched at about 16 × speed, so that the search for the entire area is performed at 8 × speed, which may cause a significant performance drop. In order to avoid this, a method is used in which the playback speed is reset to a speed at which a predetermined maximum performance is obtained at each search. However, even if such a method is adopted, the access to the area A can be performed with the highest performance. However, in the area B, the recording medium 201 is rotated at 4000 revolutions every time a search occurs, and a timeout occurs each time. For this reason, there is a problem that the reproduction time is not effectively shortened.

In other words, the conventional optical disk reproducing apparatus 200 cannot achieve both access performances such that the area A and the area B are accessed with the highest performance. In addition, a method of adopting a high-performance motor having a large torque of the medium rotating motor 202 and reducing the time spent changing the rotation speed of the recording medium 201 depending on the motor performance was also studied. Since it takes time in seconds, it was not possible to expect any significant improvement. Also, as described above, the recording medium 20
The surface of the disc 1 may be damaged by touching by a user, or the weight balance may be lost due to the attachment, and when considering that the weight balance may be lost at the time of manufacturing the medium, a disc including the weight balance may be considered. Unlike the case of reproducing an optical disk that satisfies the quality of the medium sufficiently, when reproducing a recording medium having such a quality problem, there is a problem that sufficient reproduction performance cannot be expected. That is, in order to maintain access and reproduction performance to a specific area of the recording medium, it is necessary to reduce the reproduction performance to another area, and especially a recording medium whose weight balance has been lost due to use by a user after manufacturing, Alternatively, there has been a problem that a recording medium whose entire recording surface has been damaged by long-term use cannot provide good reproduction performance.

[0014] In order to solve the above problems, it is an object of the present invention to enable data to be read at a reading speed of the highest performance at all times in accordance with individual differences of a disc-shaped recording medium.

[0015]

In order to achieve the above-mentioned object, a disk-shaped recording medium on which a constant linear velocity is recorded is rotated at a constant angular velocity, and reproduced according to an inherent reproduction velocity linearly changing in a radial direction. Reproducing means, dividing the information recording surface of the disc-shaped recording medium into a plurality of regions in the radial direction, and calculating the ratio of the number of access failures to the number of access times when accessing the divided region as an access failure ratio; When the access failure rate exceeds a preset threshold,
Reproduction speed changing means for changing the angular velocity to change the specific reproduction speed in the area to a lower speed side.

The reproduction speed changing means counts and stores the number of accesses to the divided area, an access failure number storage circuit that counts and stores the number of access failures to the area, A reproduction speed storage circuit for storing the set reproduction speed.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a circuit diagram showing an embodiment of an optical disk reproducing apparatus to which the disk-shaped recording medium reproducing apparatus of the present invention is applied, and FIG. 2 is a circuit for storing the number of times of access and the number of times of access failure shown in FIG. FIG. 3 is a diagram showing the internal structure of the speed storage circuit, FIG. 3 is a flowchart for explaining the reproduction speed determination operation by the control CPU shown in FIG. 1, and FIG. 4 is an optical pickup of the optical disk reproducing apparatus shown in FIG. FIG. 4 is a diagram illustrating an example of a relationship between a position and a reproduction speed. In the following description, for the sake of convenience, a case where the area of the recording medium 201 is roughly divided into two areas A and B as shown in FIG. 6 will be described. For the sake of simplicity, it is assumed that the recording surface of the recording medium 201 is uniformly damaged, and stable reading cannot be performed at a reproduction speed exceeding 16 times speed.

An optical disk reproducing apparatus 100 shown in FIG.
The control CPU 205 stores an access count storage circuit 101, an access failure count storage circuit 102, and a reproduction speed storage circuit 10.
3 and these circuits 101 to 103
Is characterized in that data can always be read at the highest performance reading speed according to the individual difference of the disc-shaped recording medium. The access number storage circuit 101 stores the area A,
The number of accesses is counted and stored for each area B. The access failure frequency storage circuit 102 counts and stores the access failure frequency for each of the areas A and B. The reproduction speed storage circuit 103 is a circuit that stores the reproduction speed for each of the areas A and B.

In this embodiment, as shown in FIG. 2, the inside of each of the circuits 101 to 103 divides a storage area corresponding to the areas A and B, respectively.
Are divided into a pair of circuits a and b with subscripts a and b corresponding to. Further, these circuits 101 to 103 may be configured by using a part of a buffer memory mounted on a general optical disk reproducing apparatus, or may be configured by using a control CP.
The memory incorporated in the U205 can be used, and the type of the storage medium is not an essential problem.

The control CPU 205 calculates the ratio (%) of the number of times of access failure to the number of times of access, compares it with a preset threshold value, and if an access failure rate exceeding the threshold value occurs, , And functions to change the reproduction speed in the area to a lower speed side. This control CPU 2
The playback speed set by 05 is stored in each of the circuits 103a and 103b in the playback speed storage circuit 103.

First, at the time of initialization of the optical disc reproducing apparatus 100, in step (10) shown in FIG.
The access number storage circuit 101, the access failure number storage circuit 102, and the reproduction speed storage circuit 103 are initialized. In this example, the access number storage circuits 101a and 101b and the access failure number storage circuits 102a and 102b each have an initial value of "0", and the reproduction speed storage circuit 103.
The initial values of “a” and “103b” are “8-20X”. Note that “8-20X” indicates a state in which the medium rotation motor 202 is rotated at approximately 4000 revolutions per second, and the data reading speed when the optical pickup 203 is at the innermost circumference is 8 ×.
Data reading speed at the outermost periphery at double speed is 20
It means double speed. The threshold value for determining the access failure rate calculated from the two count values is set to “80%” here, and this threshold value is resident in the control CPU 205 as an invariable value. It has been set.

The relationship between the reading position of the optical pickup 203 and the reproducing speed is shown in FIG. 6 assuming that the normal recording medium 201 is the object to be reproduced, and the reproduction is performed at the specific reproducing speed specified in this relationship. Be started. First,
It is assumed that an access from the HOST device (not shown) to the area A or the area B of the recording medium 201 is started through the HOST I / F 207. The control CPU 205
The position of the optical pickup 203 is calculated from the data read address specified through the OST I / F 207,
The playback speed is read from one of the playback speed storage circuits 103a and 103b according to whether the playback speed is the area A or the area B, and the CD-ROM is set so that the read playback speed becomes the read playback speed.
A command is issued to the signal processing circuit 206 and the CD signal processing circuit 204 to execute data reading. At this time, a determination step (2) for determining whether or not there is access to the area.
In a determination step (30) following the step (0), it is determined whether or not the access to the accessed area has failed.

If the access is successful at the time of the judgment in the judgment step (30), the step (40)
As shown in (1), the number of times stored in the access number storage circuit 101a is increased by one for access to the area A, and the number of times stored in the access number storage circuit 101a is increased by one for access to the area B. increase. On the other hand, if the access fails, that is, normal access or normal data reading cannot be performed at the reproduction speed stored in the reproduction speed storage circuit 103 for the area, and the rotation speed of the storage medium 201 is reduced to retry. When the access is performed, the number of times stored in the number-of-access-failures storage circuit 102 is increased by one, as shown in step (31).

As an example, it is assumed that the areas A and B shown in FIG. 5 are accessed in the following order from the HOST I / F 207, and the success or failure of each access result is as follows. 1. Area A Successful access 2. 2. Area B access successful 3. Area B access failure 4. Area A access successful 5. Area A access failure 6. Area B access failure 7. Area A access successful 8. Area B access failure Area B Access failure The command that instructs access from the above 1 to 9 is HO
Each time the data is supplied from the HOST device via the ST I / F 207, the control CPU 205 calculates whether it is the area A or the area B on the recording medium 201 from the data reading address included in the command. Further, the reproduction speed is read from the corresponding reproduction speed storage circuit 103, and a command is issued to the CD-ROM signal processing circuit 206 and the CD signal processing circuit 204 so that the read reproduction speed is obtained, and the data is read. At the same time, the value stored in the access number storage circuit 101 is updated or
Alternatively, if necessary, the access failure frequency storage circuit 10
The value stored in 2 is updated. These steps are completed in a very short time as compared with the moving time of the optical pickup 203. This is because the movement of the optical pickup 203 involves physical spatial movement and usually requires several tens of milliseconds, but the access number storage circuit 101, the access failure number storage circuit 102, and the reproduction speed storage circuit 103 must be checked. This is because the update is completed in at most several tens of μs.

Therefore, the processing load on the control CPU 205 can be largely ignored. Therefore, by repeating the above steps, the respective storage states of the access count storage circuit 101, the access failure count storage circuit 102, and the reproduction speed storage circuit 103 at the time when the above processes 1 to 9 are completed are as follows, for example. Become like Access frequency storage circuit 101a 4 times Access frequency storage circuit 101b 5 times Access failure frequency storage circuit 102a 1 time Access failure frequency storage circuit 102b 4 times

Each time the control CPU 205 completes each of the above processes 1 to 9, the access number storage circuit 101 and the access failure number storage circuit 10
The access failure rate is calculated from the values respectively stored in 2. In the case of this example, when the process 8 is completed, the access failure rate for each area does not fall below the preset failure rate threshold value of 80%. Since the access failure rate becomes 80%, the judgment result in the judgment step (50) is received, and in step (60), the storage content of the reproduction speed storage circuit 103b is changed from "8-20X" to "16X".
As a result, the relationship between the position of the optical pickup 203 and the reproduction speed is as shown in FIG. Note that “16X” defined here depends on the position of the optical pickup 203 so that the read speed is constant at 16 × speed.
02 means to control the rotation speed. So-called C
This refers to rotating at a speed just 16 times the rotation speed of a D (compact disc) player.

Thereafter, when an access from the HOST device to the area B of the recording medium 201 occurs through the HOST I / F 207, the control CPU 205 causes the reproduction speed "16X" read from the reproduction speed storage circuit 103b to be set to the CD. -Issue commands to ROM signal step 206 and CD signal step 204 to perform data reading. All subsequent accesses to area B are 16
Double speed. Thus, depending on the quality of the storage medium 201, 1
When an access is made to the area B, which has a high probability that the step cannot be completed normally at a reproduction speed exceeding 6 times speed,
Steps can be started at 16 times speed from the beginning of access. Therefore, the medium rotating motor 202
Is temporarily rotated at about 4000 revolutions, and the waiting time which cannot be avoided by the conventional method such as lowering the rotation speed of the medium rotation motor 202 to 16 times speed due to access failure becomes unnecessary, and the data is read efficiently. Can be performed. On the other hand, with respect to the area A, data can be read without lowering the reproduction speed more than necessary, and the best is achieved without using a medium rotation motor having a torque larger than necessary as in the related art. The performance can be brought out.

In the above embodiment, the case where the number of areas is at most two has been described. However, as the number of areas is increased and the area is made smaller, data can be read at the maximum reproduction speed corresponding to the recording medium. It goes without saying that the basic realization method is not different from the method described above even when the number of areas is two or more.

The access to the area B in the above-mentioned processing 2 is the first access to the area B in fact. However, if this access fails, the access failure rate becomes 100%. The reproduction speed for the area B generated in the above becomes "16X". However, this cannot read data efficiently. Therefore, in the case where the number of accesses is a small number of times, the calculated probability is not so relied on.
For example, one of the methods is to use a technique of calculating the probability from the time point when the number of times exceeds ten times, and thus, it is possible to more appropriately control the reproduction speed.

An access frequency storage circuit 101, an access failure frequency storage circuit 102, and a reproduction speed storage circuit 103
Is a value corresponding to the storage medium 201. Therefore, when the storage medium 201 is exchanged, for example, the insertion / removal of the tray holding the storage medium is detected, and the access count storage circuit 101 and the access failure count storage The values stored in the circuit 102 and the reproduction speed storage circuit 103 may be returned to the initial values.

In the above embodiment, the case where an optical disk such as a CD-ROM is used as the disk-shaped recording medium is taken as an example. However, the disk-shaped recording medium is not limited to the optical disk, but may be another recording medium.

[0032]

As described above, according to the present invention,
The disc-shaped recording medium on which the constant linear velocity is recorded is driven to rotate at a constant angular velocity, and reproduced in accordance with the inherent reproduction speed linearly changing in the radial direction, and the information recording surface of the disc-shaped recording medium is moved in a plurality of radial directions. The area is divided into areas, and the ratio of the number of access failures to the number of accesses when accessing the divided area is calculated as an access failure rate. When the access failure rate exceeds a preset threshold, the angular velocity is calculated. Since the configuration is such that the specific reproduction speed in the area is variably changed to the low speed side, when accessing an area having a high probability that normal reading cannot be completed at a reproduction speed exceeding a certain speed due to the quality of the storage medium, The playback speed is reduced only for these specific areas to enable normal reading, while the area accessible at the playback speed specific to the device is reduced. Normal access is possible without reducing the playback speed, and the playback speed determined for each area unique to the recording medium can be maintained. There is no need to use a medium rotation motor with an excessively large torque because there is a waiting time until the data is read and the playback speed is reduced. Discs can be reproduced with the highest performance commensurate with the quality of the discs, so that even disc-shaped recording media whose weight balance has been lost due to manufacturing defects, scratches or deposits on the surface, and sufficient reproduction Excellent effects such as performance can be exhibited.

Also, in the present invention, the reproduction speed changing means preferably includes an access number storage circuit for counting and storing the number of accesses to the divided area, and an access failure number storage circuit for counting and storing the number of access failures to the area. And a playback speed storage circuit for storing a playback speed set for each area, so that the number of accesses and the number of access failures are stored for each playback area, and an accurate access failure for each playback area divided into a plurality of areas is stored. Calculate the rate, and can properly manage and grasp the appropriate playback speed according to the quality of the recording medium for each playback area. Since an appropriate playback speed is selected, there is an effect that the disc-shaped recording medium can be reproduced with the highest performance corresponding to the quality of the recording medium. .

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an embodiment of an optical disk reproducing apparatus to which a disk-shaped recording medium reproducing apparatus of the present invention is applied.

FIG. 2 is a diagram showing each internal structure of an access count storage circuit, an access failure count storage circuit, and a reproduction speed storage circuit shown in FIG.

FIG. 3 is a flowchart for explaining a reproduction speed determination operation by a control CPU shown in FIG. 1;

FIG. 4 is a diagram showing an example of a relationship between a position of an optical pickup and a reproducing speed of the disc-shaped recording medium reproducing device shown in FIG.

FIG. 5 is a circuit diagram showing an example of a conventional optical disc reproducing apparatus.

FIG. 6 is a diagram showing a relationship between a position of an optical pickup and a reproducing speed of the optical disk reproducing device shown in FIG.

FIG. 7 is a diagram showing a reproduction area of an optical pickup capable of following a track on a defective recording medium.

FIG. 8 is a flowchart for explaining a control operation when data is read from the inner peripheral side to the outer peripheral side of the recording medium.

[Explanation of symbols]

 REFERENCE SIGNS LIST 100 optical disc reproducing device 101 access count storage circuit 101a access count storage circuit for area A 101b access count storage circuit for area B 102 access failure count storage circuit 102a access failure count storage circuit for area A 102b access failure to area B Number-of-times storage circuit 103 Reproduction speed storage circuit 103a Reproduction speed storage circuit for area A 103b Reproduction speed storage circuit for area B 201 Recording medium 202 Medium rotation motor 203 Optical pickup 204 CD signal processing circuit 205 Control CPU 206 CD-ROM signal processing Circuit 207 HOST I / F 208 Driver

Claims (2)

[Claims] 1. A reproducing means for rotating a disk-shaped recording medium on which a constant linear velocity is recorded at a constant angular velocity and reproducing according to an inherent reproduction speed linearly changing in a radial direction, and information on the disk-shaped recording medium. Dividing the recording surface into multiple areas in the radial direction,
When the divided area is accessed, the ratio of the number of access failures to the number of access times is calculated as an access failure rate, and when the access failure rate exceeds a preset threshold, the angular velocity is varied. A reproducing speed changing means for changing a specific reproducing speed in the area to a lower speed side. 2. The reproduction speed changing means includes: an access number storage circuit that counts and stores the number of accesses to the divided area; an access failure number storage circuit that counts and stores the number of access failures to the area; 2. The disc-shaped recording medium reproducing apparatus according to claim 1, further comprising: a reproducing speed storage circuit for storing the set reproducing speed.