JP2002269929A - Disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a disk device that less causes the opportunity of transmission of reproduction information including an error by trying reading for many times in the case of detecting an error in the reproduced information while avoiding interruption of real time reproduction. SOLUTION: The upper limit for the number of read retrial execution times is revised depending on the capacity of cache data, that is, the upper limit of the number of read retrial execution times is increased as the capacity of cache data increases so as to conduct many more read retrials. As the time required for one read retrial decreases, the capacity of the cache data transmitted in the read retrial period is reduced. Hence the capacity of the cache data corresponding to the upper limit of the minimum read retrial execution number of times except zero is decreased as the time required for one read retrial decreases so that the read retrial can be made to the utmost even when the capacity of the cache data is small. Moreover, the time required for one read retrial is estimated by taking into account a rotating speed of the disk.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk device capable of reproducing a disk as an information recording medium, and more particularly to a case where a reproduction speed is defined as in the case of reproducing video or music from a disk. The present invention also relates to a technique for reading information to be continuously reproduced and continuously reproducing the information at a specified reproduction speed.

[0002]

2. Description of the Related Art Continuous reproduction of information to be continuously reproduced at a prescribed reproduction speed at a prescribed reproduction speed is hereinafter referred to as real-time reproduction. The playback speed is specified like video and music. From a disc on which information to be played continuously is recorded, this information is read at a transfer rate higher than the specified playback speed, and this is temporarily stored in a buffer memory. After storing the information in the buffer memory, this information is transmitted from the buffer memory, and is continuously reproduced at a specified reproduction speed, thereby realizing a disk device that realizes real-time reproduction.

When the disk device reads reproduction information such as video or music from the disk, an error occurs in the reproduction information due to the influence of disturbance such as vibration applied to the disk device or the effect of a scratch on the disk. There are cases. In order to prevent this error, in the disk device, together with the reproduction information from the disk, a CIRC (Cross Interle
Saved-Solomon Code) and other known error correction methods are read to thereby detect and correct errors contained in the reproduction information. However, when the degree of error exceeds the limit of the correction capability of the error correction method, the error cannot be corrected. When playing video or music using playback information that contains errors, some of the video may be distorted,
Noise is included in the music, adversely affecting playback.

When a read retry is performed on reproduced information containing an error, disturbance such as vibration applied to the disk device changes, and the influence of the disturbance on the reading operation changes, so that error correction may be possible. If the disc has scratches, etc., the influence of the scratches on the disc on the reading operation can be reduced by changing the parameters related to the reading operation set in the disc device, for example, servo gain. In contrast to the previous reading, error correction becomes possible, and reproduction information containing no error may be obtained. For example, if the servo gain is high, it is likely to react to a scratch and the servo will go off. However, if the servo gain is lowered, the reproduced information may be readable. As described above, the disk device can obtain an opportunity to obtain error-free reproduction information by performing the read retry.

[0005] However, in the case of real-time reproduction by a disk device, if all cache data (reproduction information of video and music stored in the buffer memory of the disk device) is completely transmitted during read retry, There is a problem that real-time playback is interrupted. In order to deal with this problem, it is conceivable to apply the following countermeasures to the disk device when performing real-time reproduction.

In the first disk device, even if an error is detected in the reproduction information read from the disk, the reproduction information is obtained as cache data without performing a read retry in order to avoid interruption of the real-time reproduction. Send out.

In the second disk device, when an error is detected in the reproduction information read from the disk, one or more times of the first
The read retry is performed a number of times up to a certain specified number A, and an opportunity is provided to obtain error-free reproduction information. Here, in order to reduce the possibility that the real-time reproduction is interrupted, the specified number of times A is information that does not hinder reading operation temporarily (information that does not require real-time reproduction, for example, information related to a disc). This is characterized in that the value is smaller than a second predetermined number B of times set as the upper limit of the number of times of read retry when reading information or information created by the user. In addition, the specified number of times A
If the error cannot be corrected even if only the read retry is repeated, the reproduction information is acquired as cache data and transmitted.

In the third disk device, when an error is detected in the reproduction information read from the disk, if the cache data capacity is larger than a first certain threshold value C, the third disk device performs one or more third certain specified times. A read retry is performed up to D times, and an opportunity is provided to obtain reproduction information without error. On the other hand, when the capacity of the cache data is equal to or less than the first threshold value C, in order to avoid interruption of real-time reproduction, the reproduction information is acquired as cache data without performing read retry and transmitted. When the cache data capacity is larger than the first threshold C,
If the error cannot be corrected even if the read retry is repeated the third specified number of times D, the reproduction information is acquired as cache data and transmitted.

[0009]

The first disk device does not attempt to perform a read retry for obtaining error-free reproduction information if the reproduction information read from the disk contains an error. However, it cannot be avoided that the reproduction information is reproduced.

When the reproduction information read from the disk contains an error, the second disk device always performs at least one time, up to the first specified number A, regardless of the size of the cache data. Although the specified number of times A is smaller than the second specified number of times B, all the cache data can be sent out during the read retry, and the real-time reproduction can be interrupted. Sex remains.

In the third disk device, when an error is included in the reproduction information read from the disk, if the cache data capacity is larger than the first threshold value C, the read retry is performed up to the third specified number of times D. Therefore, even when the reproduction information E including an error that cannot be corrected at all due to the influence of a fatal scratch on the disc is read, the reproduction information E must always be read by the third specified number of times D. The read retry is performed for the number of times. Therefore, first, when the capacity of the cache data decreases to the first threshold value C or less during the read retry for the reproduction information E, the reproduction information F to be read next to the reproduction information E is read. There is a problem that the opportunity to retry is lost. This is called problem G. Second, if a certain reproduction information contains an error that can be corrected by several read retries, there is a margin in the cache data capacity and the number of times exceeds the third specified number D. Even if the cache data capacity is extremely unlikely to be equal to or smaller than the first threshold value C even if the read retry is performed, the read retry more than the third specified number of times D is not attempted. As a result, there is a problem that reproduction information including an error may be transmitted. This is called problem H.

Here, if a relatively small value is set as the third prescribed number of times D, the number of times of read retries for reproduction information containing an error becomes relatively small, so that problem G may occur. On the other hand, there is a problem that the probability of occurrence of the problem H increases. Let's call this problem I. On the other hand, the third prescribed number of times D
Is relatively large, the number of read retries for the reproduction information including the error becomes relatively large, so that the possibility of the problem H can be reduced. There is a problem that the possibility of occurrence is high. This is called problem J. As described above, the problem I occurs when a relatively small value is set to the third specified number D, and the problem J occurs when a relatively large value is set to the third specified number D. . In other words, the problem with the third disk device is that even if the upper limit value (specified number of times D) is increased or decreased, there is a problem because only one upper limit value is set for the number of executions of read retries. That's what it means.

It is an object of the present invention to provide a disk device which can reduce the number of cases in which erroneous reproduction information is transmitted while avoiding interruption of real-time reproduction.

[0014]

In order to achieve the above object, according to the present invention, when an error is detected in reproduction information read from a disk by a disk device, the amount of cache data is small, and a read retry is performed. If the possibility that the cache data will be completely exhausted is extremely high, the read information is stored in the buffer memory as cache data without performing a read retry in order not to interrupt the real-time reproduction. On the other hand, if the capacity of the cache data is sufficiently ensured and the possibility of the cache data being completely sent out during the read retry is extremely low, the read retry is performed. At that time, change the upper limit of the number of read retry executions according to the size of the cache data capacity, and increase the upper limit of the number of read retry executions as the cache data capacity increases, and perform more read retries To be able to do. Further, as the time required for one read retry becomes shorter, the amount of cache data transmitted during the read retry becomes smaller. Therefore, as the time required for one read retry becomes shorter, the minimum value excluding 0 becomes smaller. The capacity of the cache data corresponding to the upper limit of the number of times of execution of the read retry is reduced, and the read retry can be performed as much as possible even if the capacity of the cache data is small. Note that the time required for one read retry is estimated in consideration of the rotation speed of the disk.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings using examples. FIG. 1 is a block diagram showing one embodiment of a disk drive according to the present invention. The figure shows an example of an optical disk device. The optical pickup 103 irradiates the optical disk 101 with laser light emitted from a laser diode (not shown) incorporated in the optical pickup 103, converts the reflected light into an electric signal, and outputs the electric signal. . The RF signal processing circuit 104 includes the optical pickup 1
A data signal and a servo error signal are generated from the electric signal output from the control unit 03. The data signal is input to the digital signal processing circuit 105, and the servo error signal is input to the servo processor 108. Digital signal processing circuit 10
5 digitizes the input data signal, performs error detection and error correction, and then converts this into a buffer memory 10.
Record in 6. The servo processor 108 controls the spindle motor 102 and the optical pickup 103 in accordance with the servo error signal and an instruction from the microcomputer 107 that monitors the status of the servo error signal obtained via the servo processor 108, and controls a predetermined rotation speed. Optical disk 1
01 and rotate the laser beam at a desired position on the optical disk 101.

When the digital signal processing circuit 105 detects that there is an error in the information read from the optical disk 101, the microcomputer 107 instructs execution of a read retry as necessary. The cache data stored in the buffer memory 106 is transferred to the digital / analog converter 1 at a predetermined transfer rate via the digital signal processing circuit 105.
09, where the digital information is converted into an analog signal and then transmitted from the analog signal line 110 to a video or music playback unit (not shown).
Real-time reproduction of video or music is performed.
Alternatively, the cache data stored in the buffer memory 106 is transmitted as digital information to the host computer 112 via the digital signal processing circuit 105 and the data bus 111, and the host computer 112 having a reproduction function of video or music is transmitted to the host computer 112. By reproducing this reproduction information at a predetermined reproduction speed, real-time reproduction is performed.

The information recorded on the optical disk is logically divided into basic units called sectors. For example,
In the case of music reproduction information in a compact disc (hereinafter, referred to as a CD), information of a capacity of 2352 bytes is allocated to one sector. On the other hand, the optical disk 1
In 01, sections for storing information of the same capacity as the sector are sequentially arranged from the inner peripheral side. After performing a predetermined process, the reproduction information is divided into unit amounts accommodating the same amount of information, and is sequentially arranged in this section from the inner peripheral side. Therefore, for convenience, the cache data capacity will be expressed in sector units hereinafter.

Hereinafter, the flow of processing by the microcomputer when the reproduction information read from the optical disk includes an error in the optical disk apparatus shown in FIG. 1 will be described with reference to FIGS. 2 and 3. FIG. 2 is a schematic diagram showing an embodiment of the memory capacity of the buffer memory and the upper limit of the number of times of execution of the read retry according to the present invention. FIG.
3 shows a memory space of the buffer memory 106, threshold values of a plurality of memory capacities provided in the memory space, and an upper limit value of the number of times of read retry execution determined for each threshold value. M is the maximum value of the cache data capacity, and is determined by the recording capacity of the buffer memory 106. The first threshold X, the second threshold Y, and the third threshold Z (0 <
X <Y <Z <M) is a threshold of the memory capacity in the buffer memory 106, respectively, and a first specified number P, a second specified number Q, and a third specified number R (0 <P < Q
<R) is the upper limit value of the number of read retry executions defined for the threshold values X, Y, and Z, respectively. Hereinafter, in this embodiment, when the cache data capacity is X or less,
The upper limit values of the number of times of execution of the read retry will be described as 0 times, P times, Q times, and R times when the value is larger than X, equal to or less than Y, larger than Y, equal to or less than Z, and larger than Z.

FIG. 3 is a flow chart showing one embodiment of the processing operation when the reproduction information read from the optical disc contains an error. In the present embodiment, the processing by the microcomputer 107 can be performed so that the upper limit value of the number of executions of read retries can be increased as the cache data capacity increases. Each time an error is detected in the reproduction information, the optical disc apparatus performs the cache data capacity L at that time and the total number N of read retries performed so far for the reproduction information of a certain sector containing the error. Is confirmed, the time required for one read retry is estimated based on the rotation speed of the optical disk 101 at this time, and the threshold values X, Y,
Appropriate values are set for Z and the specified times P, Q, and R. Note that the thresholds X, Y, Z, and the specified times P, Q,
A method for setting an appropriate value for R will be described later.

FIG. 3 shows a processing operation for each sector. Therefore, when there is an error in the reproduction information, the read retry is performed according to this flow, and when the read retry is further performed, this flow is repeated again. First, it is determined whether or not an error has been detected in the read information read in step 300. If no error is detected, the process proceeds to step 312, where the reproduction information is recorded in the buffer memory as cache data without performing read retry. When an error is detected in the reproduction information, in step 301, the optical disk apparatus each time performs the cache data capacity L at that time and the total number of read retries performed so far for the reproduction information of this sector including the error. Check the number of executions N. Then, step 30
In step 2, the time required for one read retry is estimated based on the rotation speed of the optical disc 101 at this time.
In consideration of this, appropriate values are set for the threshold values X, Y, Z and the specified times P, Q, R.

Next, at step 303, it is determined whether or not the cache data capacity L is larger than the threshold value Z. If it is larger (in the case of Yes), it is determined in step 304 whether or not the total number N of read retries performed so far for the reproduction information of this sector including the error is less than a specified number R. If the number is less than the specified number R, a read retry is executed in step 305. Step 30
If the total number of executions N is equal to or greater than R in step 4, step 312
Then, the reproduction information is directly stored in the buffer memory 1.
Record at 06. As a result, if Yes is determined in step 303, read retries can be performed up to R times, and a large number of opportunities to obtain reproduction information without errors can be provided.

Next, if the cache data capacity L is equal to or smaller than the threshold value Z in step 303 (No), the process proceeds to step 306, where the cache data capacity L is equal to or smaller than the threshold value Z and is smaller than the threshold value Y. If it is larger than the threshold value Y (in the case of Yes), in step 307, the total number N of read retries performed so far for the reproduction information of this sector including the error is determined. It is determined whether or not the number is less than the specified number Q. Only when the total number of executions N is less than the specified number Q, a read retry is performed in step 308. If the total number of executions N is equal to or more than Q, the process proceeds to step 312, and the reproduction information is recorded in the buffer memory 106 as it is. As a result, step 306
In the case where it is determined as Yes, the read retry up to Q times is possible, and when the reproduction information includes an error that cannot always be corrected while providing many opportunities to obtain the reproduction information without error. Can shift to the operation of reading the next reproduction information earlier than the case where R (> Q) read retries are performed, and can suppress a decrease in cache data capacity.

If it is determined in step 306 that the cache data capacity L is equal to or smaller than the threshold value Y, the process proceeds to step 309. In step 309, it is determined whether or not the cache data capacity L is equal to or smaller than the threshold Y and larger than the threshold X. It is determined whether the total number N of read retries performed so far is less than a specified number P. If the number is less than the specified number P, the process proceeds to step 311 to perform a read retry. If the total number of executions N is equal to or greater than the specified number of times P, the process proceeds to step 312,
This reproduction information is recorded in the buffer memory 106. As a result, if it is determined to be Yes in step 309, the read retry can be performed up to P times at maximum, and while providing an opportunity to acquire reproduction information without error, an error in which the reproduction information cannot always be corrected is provided. In this case, it is possible to shift to the next read information reading operation earlier than in the case of performing Q (> P) read retries, and it is possible to further suppress a decrease in the cache data capacity.

Finally, if the cache data capacity L is equal to or smaller than the threshold X in step 309, the read information is recorded in the buffer memory 106 without performing read retry. As a result, in the case of No in step 309, that is, when there is no room for performing the read retry in the cache data capacity, the read retry is not performed, and the interruption of the real-time reproduction can be avoided.

The contents described above will be described with reference to FIG. 4 from the viewpoint of the temporal change of the cache data capacity. FIG. 4 is a characteristic diagram showing one embodiment of a temporal change of the cache data capacity in the optical disc device according to the present invention, in which the horizontal axis indicates time and the vertical axis indicates cache data capacity L. X, Y, and Z on the vertical axis are memory capacity thresholds that determine the upper limit of the number of read retries. 0, P, Q, and R shown in the figure are read retries when the cache data capacity L is less than or equal to the memory capacity threshold value X, greater than X, less than Y, greater than Y, less than Z, and greater than Z. Indicates the upper limit of the number of executions. Now, temporarily, P
= 1, Q = 2, R = 4. Time 0 indicates the cache data capacity when a predetermined time has elapsed after the start of reproduction. A characteristic line 400 indicates a temporal change of the cache data capacity L. From time 0 to time t _1, the direction of reading speed goes greater than the delivery rate of the cache data, because there is no abnormality in the reading operation, the capacity L of the cache data in the buffer memory is slide into increased. From time 0 to time t ₁ or at or above time t ₃ , the cache data capacity L is increasing and decreasing as a whole because the management by the microcomputer 107 is performed on a sector-by-sector basis. It shows that it looks like the figure when viewed.

It is assumed that a read error has occurred at time t ₁ . In this case, the processing operation is started from the start in FIG. Since the cache data capacity L at time t ₁ is larger than the threshold value Z, the upper limit of the number of read retry executions is set to R = 4, and read retry in sector units is started. Thereafter, since data is not input to the buffer memory during the execution of the read retry, cache data is transmitted at a predetermined speed of information reproduction, and the capacity is reduced.
When first read retry also a read error occurs at time t ₂ has been completed, also the processing operation is started from the start of FIG. Since the cache data capacity L at time t ₂ is larger than Y and equal to or smaller than Z,
The upper limit of the read retry execution count is replaced with Q = 2. The total number of read retries at this time is one,
Since it is smaller than the upper limit value Q = 2, the read retry in the sector unit is executed again. In the second time t ₃ when completing the read retry, the capacity of the cache data L is less larger than Y Z, the upper limit of the read retry execution count remains Q = 2. On the other hand, the total number of read retries performed at this time is two, and the number of read retries performed at this point has reached the upper limit. Therefore, even if a read error has occurred, read retries are performed no further. , The current data is accepted, and the process proceeds to reading the next data.

The characteristic line 400 in FIG. 4 will be described with reference to FIG. Reading an error occurs at time t _1, the microcomputer 107 performs the processing operation of FIG. Step 300
In step 303, the cache data capacity L and the threshold are determined. Cache data capacity L
Is larger than the threshold value Z, the result is Yes in step 303, and the process proceeds to step 304. Here, since the total number of executions N is 0 and R is 4, a read retry is performed in step 305. If you still reading error at the time t ₂ of FIG. 4 has occurred, beginning from the start of Figure 3. In step 303, since the capacity L of the cache data is between the threshold value Z and the threshold value Y, the result is No.
Shift to 06. In step 306, since the cache data capacity L is larger than the threshold Y, the process proceeds to step 307. In step 307, Q is 2 and the total number of executions N is 1, so that read retry is performed in step 308. If the read error has occurred at time t _3, starting from the start of Figure 3. At time t ₃ , since the cache data capacity L is between the threshold value Z and the threshold value Y, Step 303 is No, Step 306 is determined as Yes, and the process proceeds to Step 307. In this case, the total execution number N is 2 and Q is 2, so
s, and no read retry is performed.
At 12, the reproduction information is recorded in the buffer memory 106.

In this embodiment, three values of X, Y, and Z are provided as threshold values of the cache data capacity L.
Obviously, the effect of the present invention can be obtained by providing two or more threshold values.

The memory capacity thresholds X, Y, and X which define the upper limit of the number of read retries in this embodiment will be described below.
A method for setting appropriate values to Z and the upper limit values P, Q, and R of the number of read retry executions determined for the threshold values X, Y, and Z will be described. When setting the memory capacity threshold value that defines the upper limit of the number of times of read retry, even if the number of read retries is performed up to the upper limit of the number of times of read retry that is defined for this threshold, the cache data capacity Is larger than the memory capacity of the threshold, it is necessary to secure a memory capacity that does not cause the cache data to be lost as the threshold. The time required for transmitting the reproduction information for one sector of cache data is determined by the channel bit rate of the reproduction information of the video and music recorded on the optical disk. Therefore, in the embodiment, the time required to perform read retries the number of times equal to the upper limit value is estimated, and a memory capacity exceeding the capacity of cache data transmitted during that time is set to each threshold value. For example, in order to set the threshold X of the first memory capacity, the time required to perform read retries the specified number of times P, which is the upper limit of the number of read retries executed for this threshold, is estimated. , A value equal to or larger than the capacity of the cache data transmitted during that time is set as the threshold X of the first memory capacity. In this case, the threshold value X needs to be as small as possible so that the read retry can be performed as much as possible even when the capacity of the cache data is small. For that purpose, it is necessary to reduce the time required for performing the read retry by the specified number of times P. Since the time required for one read retry can be regarded as substantially constant under the same reading conditions in the same optical disk device, the time required for performing the read retry the specified number of times P is reduced. It is necessary to reduce the specified number P itself.
Therefore, in order to perform the read retry as much as possible even when the cache data capacity is small, the specified number of times P is set to 1 which is the smallest integer value exceeding 0.

Next, when 1 is set to the specified number of times P,
A method for setting an appropriate value for the threshold X will be described. The time required for performing one read retry is approximately the time when the optical pickup 103 performs a reverse jump on the optical disc 101 by one track, and then the optical pickup 103 reaches a position on the optical disc 101 where reproduction information to be read retried exists. It can be regarded as the time until the optical disk 101 reaches again (that is, the optical disk 101 makes one rotation). The time during which the optical disc 101 makes one rotation depends on the rotation speed at which the optical disc apparatus rotates the optical disc 101. The value depends on the transfer rate at which the optical disc apparatus reads reproduction information from the optical disc 101, and the value at which the optical disc apparatus operates.
01 is controlled by the control method. The control method in which the optical disk device rotates the optical disk 101 includes:
Generally, Constant Linear Velo
city (hereinafter referred to as CLV) method and Consta
nt Angular Velocity (hereinafter CAV)
Called. ) Method.

In the case of the CLV system, the optical disk 101 is always rotating at a constant linear velocity. Therefore, in addition to the transfer rate at which the optical disk apparatus reads the reproduction information from the optical disk 101, the reproduction information to be read is also recorded in the radial direction on the optical disk 101. The time required for the optical disc 101 to make one rotation changes depending on the position of the optical disc 101. Therefore, from the physical address assigned to the reproduction information to be read, the position in the radial direction on the optical disk 101 where the reproduction information exists is determined, and the optical disk device is determined by the transfer rate at which the optical disk apparatus reads the reproduction information from the optical disk 101. From the rotation speed of 101, the optical disk 1
Calculate the time required for 01 to make one revolution.

On the other hand, in the case of the CAV system, the optical disk 1
01 always rotates at a constant angular velocity, so that the time required for the optical disc 101 to make one rotation is constant regardless of where in the radial direction the reproduction information to be read exists on the optical disc 101. is there. Therefore, from the rotation speed of the optical disc 101 determined by the transfer rate at which the optical disc apparatus reads the reproduction information from the optical disc 101,
The time required for the optical disc 101 to make one rotation is calculated.

Here, a method for calculating the time required for the optical disk to make one rotation will be described by taking a CD as an example.
According to the standard of the CD, the area (program area) where the reproduction information is actually recorded is from a radius of 25 (mm) to a radius of 58 (m).
m), the track pitch is 1.6 (μm), C
The LV linear velocity is a fixed value between 1.2 (m / s) and 1.4 (m / s) when reproducing information is read at a 1x transfer rate. The physical address of the playback information is “minute,
Seconds, frames ”, and the beginning (the innermost circumference) of the program area is“ 0 minutes 0 seconds 0 frames ”.
Thereafter, they are sequentially assigned to the outer periphery.

First, a certain physical address “minute”
(Minute), second (second), frame (frame) ”(minute, second, and frame are respectively 0 ≦ minute ≦ 99, 0 ≦ second ≦ 5.
(9, any integer value satisfying 0 ≦ frame ≦ 74), the position on the optical disk where the reproduction information is allocated is determined. For convenience, the physical address converted into “seconds” and displayed is denoted by p, and p = (minute × 60) + (second) + (f
frame @ 75) (s). Using this value, the total line length from the beginning of the program area to the position where the physical address exists is
Assuming that the linear velocity is v (m / s), Becomes CD at the position where the physical address exists
If the upper radius is r (mm), the total line length is the radius r
It can be considered as a value obtained by dividing the area s (m ² ) of the program area up to (mm) by the track pitch 1.6 (μm). Therefore, = {(R × 10 ⁻³ ) ² × π− (25 × 10 ⁻³ ) ² × π}
(1.6 × 10 ⁻⁶ ) (m) From this, the radius r (mm) on the CD at the position where the physical address exists is: The radius on the CD can be obtained from the physical address.

Next, the time required for the optical disk to make one revolution when the reproduction information assigned to the physical address is read by the optical disk device is obtained. When the optical disk device reads an optical disk with a linear velocity v (m / s) at a transfer rate of n times the CLV method, the time t _CLV required for the optical disk to make one revolution at the position of the physical address is t _CLV. = 2π (r × 10 ⁻³ ) ÷ (v × n) (s) (2) Here, r is a value represented by (Equation 1) obtained earlier.

On the other hand, when the optical disk device has a linear velocity v (m / m
When the optical disk of s) is read by the CAV method at an innermost position (radius 25 (mm)) at an angular velocity such that an n-times transfer rate can be obtained, the time t required for the optical disk to make one rotation is t. _CAV is t _CAV = 2π (25 × 10 ⁻³ ) ÷ (v × n) (s) (Equation 3)

As described above, the time required for transmitting reproduction information for one sector of cache data is determined by the channel bit rate of reproduction information of video and music recorded on the optical disk. This time is denoted as T1.
The time required for the optical disc 101 to make one rotation is expressed as T2 by generalizing t _CLV and t _CAV obtained by this calculation. Then, the capacity L of the cache data transmitted during one rotation of the optical disc 101 becomes T2 /
This is equivalent to T1 sectors.

Accordingly, the first memory capacity threshold value X that defines the upper limit of the number of read retries in this embodiment.
Must be set to at least a value corresponding to at least T2 / T1 sector. Actually, the optical pickup 10
3 is a time required for performing a reverse jump for one track, and a time required for recovering control when the control fails, other than the time T2 (this time is described as T3 (> 0)). ) And (T2
+ T3) / T1 sector or more is set as the threshold value X.

Next, an example of a method of actually setting the threshold value X will be described by taking a CD as an example. When a CD is reproduced in real time, reproduction information for 75 sectors per second is transmitted from the cache data according to the standard. Assuming that the optical disk apparatus converts the reproduction information to a linear velocity of 1.2 (m /
Assuming that the CD is read from the CD of s) by the quadruple-speed CLV method, the capacity of the cache data transmitted during one rotation of this CD is calculated by using the above-obtained (Equation 2), T2 / T1 = t _CLV / (1/75) = {2π (r × 10 ⁻³ )} (1.2 × 4)} / (1/75) ≒ 0.1r (sector) Note that r represents that the reproduction information to be read is a CD.
The position in the upper radial direction is indicated, and its value is obtained by using (Equation 1) previously obtained from the physical address assigned to the reproduction information. As an example, if the reproduction information to be read exists at the innermost circumference of the CD, r =
By substituting 25 (mm) and rounding up the fraction to make an integer, T2 / T1 ≒ 2.5 ≒ 3 (sector) When reproduction information to be read exists at the outermost periphery of this CD, r = 58 ( mm), (the fraction is similarly rounded up and converted to an integer.) T2 / T1 ≒ 5.8 ≒ 6 (sector).

The T2 / T1 obtained as described above is added to the T3
The threshold value X is obtained by adding the margin of / T1, but the time T3 is not a value obtained theoretically but a value obtained experimentally. If a relatively large value is set for T3, the margin of T3 / T1 is increased, and the chance of performing a read retry is relatively reduced. On the other hand, if a relatively small value is set for T3, T3 / T1
Since the margin of the optical pickup 103 becomes smaller, the chance of performing a read retry relatively increases. However, when an abnormal situation such as a failure in controlling the optical pickup 103 occurs, the possibility that real-time reproduction is interrupted is relatively low. Will be higher. Therefore, T3 is set to an appropriate value according to the characteristics of the optical disk device.

Here, as an example, it is assumed that T3 is set so that T3 / T1 ≒ 24 (sector). Then, the threshold X
X = (T2 + T3) / T1 = (T2 / T1) + (T3 /
T1) ≒ 3 + 24 = 27 (sectors), and when the reproduction information to be read exists at the outermost periphery of the CD, X = (T2 + T3) / T1 = (T2 / T1) + (T3 /
T1) ≒ 6 + 24 = 30 (sectors).

Next, consider the case where the optical disc apparatus changes the transfer rate for reading the reproduction information and reads the CD by the 8 × CLV method. In this case, the amount of cache data sent during one rotation of the CD is determined by
Using (Equation 2), T2 / T1 = _tCLV / (1/75) = {2π (r × 10 ⁻³ )} (1.2 × 8)} / (1/75)） 0.05r ( Sector). Note that r represents that the reproduction information to be read is a CD.
The position in the upper radial direction is indicated, and the value is obtained by using (Equation 1) previously obtained from the physical address assigned to the reproduction information.

As an example, if the reproduction information to be read is a CD
If they exist at the innermost and outermost circumferences, respectively, r = 25
(Mm) and r = 58 (mm), T2 / T1 ≒ 1.2 ≒ 2 (sector) (in the case of the innermost circumference) T2 / T1 ≒ 2.8 ≒ 3 (sector) (in the case of the outermost circumference) Assuming that the margin of T3 / T1 is 24 sectors as before, the threshold X is: X = (T2 / T1) + (T3 / T1)） 2 + 24 = 26 (sectors) (in the case of the innermost circumference) X = (T2 / T1) + (T3 / T1) ≒ 3 + 24 = 27 (sectors) (in the case of the outermost circumference). In this way, the optical disk device closes the optical disk with CL.
When reading in V format, the linear velocity of the optical disc,
The position on the optical disc where the playback information to be read exists,
Further, the time required for one read retry is estimated from the transfer rate at which the optical disk device reads the reproduction information, and the value of the threshold X is set in consideration of this.

Next, let us consider a case where the optical disk apparatus reads reproduction information from a CD having a linear velocity of 1.2 (m / s) by a quadruple speed CAV method. In this case, the capacity of the cache data transmitted during one rotation of the CD can be calculated by using the equation (3) previously obtained, as follows: T2 / T1 = t _CAV / (1/75) = （2π (25 × 10 ^-3 ) {(1.2 × 4)} / (1/75) ≒ 2.5 / 3 (sector). Assuming that the margin of T3 / T1 is 24 (sectors) as before, the threshold value X is: X = (T2 / T1) + (T3 / T1) １3 + 24 = 27
(Sector).

Next, consider a case where the optical disc apparatus changes the transfer rate for reading reproduction information and reads a CD by the 8 × CAV method. In this case, the amount of cache data transmitted during one rotation of the CD is determined by
Using (Equation 3), T2 / T1 = t _CAV / (1/75) = {2π (25 × 10 ⁻³ )} (1.2 × 8)} / (1/75) {1.2} Assuming that the margin of T3 / T1 is 24 (sectors) as before, the threshold value X is: X = (T2 / T1) + (T3 / T1) １2 + 24 = 26
(Sector). In this way, the optical disk drive converts the optical disk into a CA.
In the case of reading by the V method, the time required for one read retry is estimated based on the linear velocity of the optical disk and the transfer rate at which the optical disk device reads the reproduction information. Set.

Next, the second and third memory capacity thresholds Y,
A method for setting an appropriate value to Z will be described. When setting the memory capacity threshold one step higher, it is necessary to set the memory capacity difference for one step of the threshold to be equal to or larger than the memory capacity estimated to be transmitted during execution of one read retry. Reasonable. The time required for the optical pickup 103 to make a reverse jump on the optical disc 101 by one track can be generally considered to be sufficiently smaller than the time required for the optical disc 101 to make one rotation. Therefore, assuming that the capacity of the cache data sent during execution of one read retry is regarded as T2 / T1 sector, ignoring the margin T3 / T1 sector, the threshold Y becomes equal to the threshold Y. , A value obtained by adding a memory capacity of at least T2 / T1 sector to the threshold X is set, and a value obtained by adding a memory capacity of at least T2 / T1 sector to the threshold Y is added to the threshold Z. Must be set.

Actually, in order to allow a chance to perform a read retry for the next reproduction information of the reproduction information currently being subjected to the read retry,
The threshold value Y is at least (T2 / T1) with respect to the threshold value X.
× Set a value obtained by adding the memory capacity of P sectors or more,
The threshold value Z is at least (T2 / T1) with respect to the threshold value Y.
A value obtained by adding a memory capacity equal to or more than × Q sectors is set.

With this setting, the capacity of the cache data transmitted during execution of one read retry is regarded as T2 / T1 sector, ignoring the margin T3 / T1 sector. If the capacity of the cache data is larger than the threshold Y and equal to or smaller than the threshold Z, it is possible to perform at least P (= 1) times and up to Q times of read retries. Even after the execution, the cache data capacity is in a state at least exceeding the threshold value X. Assuming that the reproduction information that has been the target of the read retry has been read retried the number of times of the upper limit, the reproduction information is recorded in the buffer memory 106 as cache data regardless of the presence or absence of an error. In addition, since the reading speed is higher than the sending speed of the cache data, if an error is detected in reading the next reproduction information of the reproduction information targeted for this read retry, the cache data capacity at this point in time is detected. Is still at least above the threshold X. As a result, if an error is detected in the next reproduction information of the reproduction information that has been the target of the read retry, at least P
It is possible to leave an opportunity to perform (= 1) read retries.

Similarly, if it is assumed that the capacity of cache data transmitted during execution of one read retry is regarded as T2 / T1 sector, ignoring the margin T3 / T1 sector. If the capacity of the cache data is larger than the threshold value Z, the read retry can be performed at least Q times and at most R times. It is in a state exceeding at least the threshold value Y. If it is assumed that the reproduction information that has been subjected to the read retry has been read retried the maximum number of times, the reproduction information is recorded in the buffer memory 106 as cache data regardless of the presence or absence of an error. In addition, since the reading speed is higher than the sending speed of the cache data, if an error is detected in reading the next reproduction information of the reproduction information that has been the target of the read retry, the cache data capacity at this time becomes Still, the state is still at least exceeding the threshold value Y. As a result, if an error is detected in the next reproduction information of the reproduction information which has been the target of the read retry until now, if the cache data capacity at this time is equal to or smaller than the threshold Z, at least P (= 1 ) Times and a maximum of Q times of read retries can be left. If the cache data capacity is larger than the threshold Z, at least Q
It is possible to leave the opportunity to perform the read retry up to R times.

Next, a method of setting appropriate values for the upper limit values Q and R of the second and third read retry execution times determined for the threshold values Y and Z will be described. To the upper limit Q,
An integer value larger than the upper limit value P by one or more is set, and an integer value larger than the upper limit value Q by one or more is set to the upper limit value R. At this time, if the upper limit values Q and R are set to unconditionally large values, the threshold values X, Y and Z of the memory capacity are determined by the above-described method. As a result, the threshold value Z may exceed the recording capacity of the buffer memory 106. is there. Therefore, the thresholds X, Y, Z of the memory capacity
As a result of the above method, the values within a range that can be set so that the threshold value Z is smaller than the recording capacity of the buffer memory 106 are set as the upper limit values Q and R.

As a method of setting the upper limit values Q and R, Q = P
In addition to the method of increasing the upper limit of the number of executions of the read retry by one each time the threshold value of the memory capacity increases by one step, such as +1 and R = Q + 1, the read operation is performed every time the threshold value of the memory capacity increases by one step. Q = P for the upper limit of retry execution count
+2, R = Q + 4, it is possible to increase the value by two or more at a stretch. Here, if the upper limit of the number of read retry executions is increased by one each time the threshold value of the memory capacity increases by one step, the upper limit of the number of read retry executions is changed more finely than when the upper limit is increased by two or more at once. On the other hand, in order to be able to perform read retries more than a certain number m (m is a positive integer), it is necessary to provide the same number (m) of memory capacity thresholds as that. In order for the upper limit of the number of times of read retry execution to be 3 or more (m ≧ 3), cache data of a larger capacity is required. On the other hand, when the upper limit of the number of read retry executions is increased by two or more when the threshold value of the memory capacity is increased by one step, the upper limit of the number of read retry executions is changed more finely than when the upper limit is increased by one. However, since the upper limit of the number of read retries is 3 or more (m ≧ 3), the amount of cache data required is small.

When it is considered that the optical disk 101 is not damaged and the read retry is rarely required, the cache data capacity is considered to be always near the upper limit of the memory capacity of the buffer memory 106. Therefore, when the threshold value of the memory capacity is increased by one step, if the upper limit value of the number of times of execution of the read retry is set to be increased by 2 or more, if the read retry is required, more A read retry can be attempted. Conversely, if the optical disc 101 has many scratches and it is considered that a situation that requires read retries will occur frequently, it is assumed that the cache data capacity is stable near the upper limit of the memory capacity of the buffer memory 106. The upper limit of the number of read retries is set to increase by one each time the threshold value of the memory capacity increases by one step, so that the upper limit of the number of read retries can be finely adapted to changes in cache data capacity. It is possible to set a value.

One example of a method for setting the upper limit values Q and R of the number of times of execution of the read retry is as follows. At the time when the optical disc apparatus starts reading the reproduction information from the optical disc 101, the capacity of the cache data is stored in the buffer memory 1
Since the memory capacity is not stable near the upper limit value of the memory capacity of No. 06, the upper limit value of the number of read retries executed corresponding to the change of the cache data capacity is set as Q = 2 and R = 3. When the cache data capacity increases steadily and approaches the upper limit of the memory capacity of the buffer memory 106, the upper limits Q and R are changed to, for example, Q =
3, it is also possible to adopt a method of changing to R = 5 so as to be able to try more read retries if a read retry is required.

[0054]

As described above, according to the present invention, it is possible to perform many read retries on reproduced information containing errors while avoiding interruption of real-time reproduction. It is possible to reduce the number of cases in which the playback information including the playback information is transmitted.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a disk drive according to the present invention.

FIG. 2 is a schematic diagram showing one embodiment of a memory capacity of a buffer memory and an upper limit value of the number of times of execution of read retries in the optical disk device according to the present invention.

FIG. 3 is a flowchart showing an embodiment of a processing operation when reproduction information read from an optical disc contains an error.

FIG. 4 is a characteristic diagram showing one embodiment of a temporal change in cache data capacity in the optical disc device according to the present invention.

[Explanation of symbols]

101: optical disk, 102: spindle motor, 10
3 ... optical pickup, 104 ... RF signal processing circuit, 10
5 ... Digital signal processing circuit, 106 ... Buffer memory,
107: microcomputer, 108: servo processor, 109
... a digital / analog converter, 110 ... an analog signal line, 111 ... a data bus, 112 ... a host computer.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G06F 3/06 305 G06F 3/06 305K 12/08 501 12/08 501G 541 541D 13/38 310 13/38 310D G11B 20/10 G11B 20/10 A H04N 5/85 H04N 5/85 Z F term (reference) 5B005 JJ12 MM11 5B065 BA01 CE14 EA04 5B077 DD11 5C052 AA02 AC00 BB01 DD09 DD10 5D044 AB05 AB07 BC03 CC06 DE12 DE6983

Claims (7)

[Claims] A read circuit for converting an electric signal into digital information; an error detection circuit for detecting an error in the digital information; a buffer memory for temporarily storing the digital information; A read retry function for re-reading a section on the disk on which the digital information containing the error is recorded when an error is detected, and storing the read digital information in the buffer memory. When an error is detected, an upper limit value for limiting the number of executions of the read retry is determined in accordance with the amount of cache data which is digital information already stored in the buffer memory, and the number of times less than the upper limit value is determined. The digital information is temporarily stored in the buffer memory by executing a read retry only for By sending the cached data, the disk device comprising continuously be played at a specified playback speed. 2. The disk device according to claim 1, wherein the upper limit of the number of times of execution of the read retry determined according to the capacity of the cache data is a plurality of thresholds provided within a range of the recording capacity of the buffer memory. Wherein the upper limit value of the read retry execution number defined for the maximum threshold value among the threshold values is the largest read retry execution number. 3. The disk device according to claim 1, wherein the upper limit value of the number of times of execution of the read retry determined according to the capacity of the cache data is a plurality of threshold values provided within a range of the recording capacity of the buffer memory. Wherein the upper limit of the number of times of execution of read retries, which is determined with respect to the threshold of the memory capacity, increases as the threshold of the memory capacity increases. 4. The disk drive according to claim 1, wherein the upper limit of the number of times of execution of the read retry determined according to the capacity of the cache data is a plurality of thresholds provided within a range of the recording capacity of the buffer memory. Wherein the read retry is not performed when the cache data capacity is equal to or smaller than a minimum threshold value among the plurality of threshold values. 5. The disk device according to claim 1, wherein the upper limit value of the number of times of execution of the read retry determined according to the capacity of the cache data is a plurality of threshold values provided within a range of the recording capacity of the buffer memory. And the threshold value secures a capacity equal to or greater than the cache data capacity estimated to be transmitted during execution of the read retry the number of times of the upper limit value defined for the threshold value. A disk device characterized by being performed. 6. The disk device according to claim 1, wherein the upper limit of the number of times of execution of the read retry determined according to the capacity of the cache data is a plurality of thresholds provided within a range of the recording capacity of the buffer memory. And the total number of read retries already performed at the stage of newly executing the read retries for the digital information to be read The disk device according to claim 1, wherein the read retry is performed only when the upper limit of the number of read retry executions in the data capacity is less than the upper limit. 7. The disk device according to claim 5, wherein the amount of cache data transmitted during execution of read retries the number of times equal to the upper limit value defined with respect to the threshold value takes into consideration the rotational speed of the disk. A disk device characterized by performing estimation.