JP2002304749A - Optical disk drive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical disk drive which can shorten the time needed for seeking for moving a pickup head to a target track by preventing the optical pickup head from jumping out beyond the outermost peripheral track of an optical disk. SOLUTION: The optical disk drive once detecting the optical pickup head jumping out beyond the outermost peripheral track 21 of the optical disk during the seeking for moving the pickup head to the target track moves the pickup head to the inner peripheral side of the optical disk to make a focus search and then performs re-seeking for moving the pickup head to the target track again. In this re-seeking, seeking in failure which is less than the number of movement tracks is repeated to move the pickup head to the target track. In the re-seeking, the moving speed of a thread becomes slower than the moving speed of a thread in the seeking in failure, so the seeking is prevented from ending in failure again.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to CD, MD, D
The present invention relates to an optical disk device for reading data recorded on an optical disk such as a VD and writing data on the optical disk.

[0002]

2. Description of the Related Art Conventionally, there has been an optical disk apparatus for reading data recorded on an optical disk such as a CD, MD, or DVD, and writing data on the optical disk. As is well known, an optical disc has concentric or spiral tracks formed on a recording surface. The optical disk device reads data by detecting reflected light of a light beam applied to the track with a pickup head. In writing data, the track is irradiated with a light beam. The pickup head is mounted on a sled configured to be movable in the radial direction of the optical disc so that data can be read from or written to an arbitrary track formed on the optical disc. Further, an actuator is provided for moving the lens of the pickup head in the radial direction of the optical disk with respect to the sled.

The optical disk device sometimes performs a seek operation to move a pickup head (light beam irradiation position) from a current position to a target track when reading or writing data recorded on the optical disk. . The target track mentioned here is a track from which data is read or data is written. There are cases where seek involves movement of a sled and cases where seek is performed only by movement of a lens by an actuator. When the number of tracks for moving the pickup head is large, the sled needs to be moved.

[0004] The seek control involving the movement of the thread is as follows.
The following procedure was used. The number of tracks from the current position of the pickup head to the target track is calculated. The sled is moved in the direction of the target track, and when the pickup head approaches the target track to some extent, the sled is stopped.

[0005] Thereafter, the lens of the pickup head is moved in the direction of the target track by the actuator, and the irradiation position of the light beam is adjusted to the target track.

Note that the above operation is not executed in a seek without moving a thread.

In the above seek, the number of tracks to which the pickup head has been moved is obtained from the following tracking error signal. The tracking error signal is a signal based on the amount of reflected light from the optical disk detected by the pickup head. As is well known, a mirror portion that totally reflects a light beam is formed between adjacent tracks on an optical disk. Therefore, when the pickup head is moved in the radial direction of the optical disk, a sinusoidal signal (one of which is a tracking error signal) that is generated by one wavelength each time the pickup head crosses the track is obtained. Therefore, the number of tracks to which the pickup head has moved can be obtained by counting the number of waves of the tracking error signal.

In a general optical disk device, as the number of tracks for moving the pickup head increases, the moving speed of the sled is increased to shorten the time required for a seek with a large number of tracks for moving the pickup head. . The faster the sled moves, the less time the pickup head has to cross the track,
The period of the tracking error signal is reduced. For this reason, in the case of a seek in which the number of tracks for moving the pickup head is large, the wave number of the tracking error signal cannot be accurately counted (missing occurs), and the pickup head may jump out of the outermost track of the optical disc. (Seek sometimes failed.)

When the pickup head jumps out of the outermost track of the optical disk, it loses focus and enters a focus-off state. Focus-off is a state in which the optical disk is out of focus.

In a conventional optical disk apparatus, when a focus is turned off at the time of seek, a focus search for focusing on the optical disk is performed at that position. If the focus cannot be turned on (if the optical disk cannot be focused), the pickup head is moved. It was determined that it had jumped out of the outermost track of the optical disc.

The focus-off state is caused by
This is not only when the pickup head jumps out of the outermost track of the optical disc.

When the optical disk device determines that the pickup head has jumped out of the outermost track of the optical disk, it moves the pickup head to the inner peripheral side of the optical disk by a predetermined amount (or for a predetermined time) and performs a focus search again. When the focus can be turned on, re-seek to move the pickup head to the target track is performed again, and the pickup head is moved to the target track.

By the way, if the pickup head protrudes outside the outermost track of the optical disk,
The focus cannot be turned on even if the focus search is performed at that position. That is, there is a problem that the focus search is uselessly performed, and as a result, the time required for the seek becomes long.

Therefore, when the focus is turned off at the time of seeking, the pickup head is immediately moved to the inner peripheral side of the optical disk by a predetermined amount (or for a predetermined time) without performing the focus search at that position, and thereafter the focus search is performed. (Japanese Patent Laid-Open No. 11-2655)
No. 12). Accordingly, the time required for the seek can be reduced without performing the useless focus search described above.

[0015]

However, the main cause of the pickup head jumping out of the outermost track of the optical disk during seek is that the tracking error signal can be counted accurately because the sled movement speed is too high. Instead, it was lost.

On the other hand, when the pickup head protrudes outside the outermost track of the optical disk, the pickup head must be returned inside the outermost track. Therefore, in a general optical disk device, when the pickup head protrudes outside the outermost track of the optical disk, the pickup head is returned to a position near the innermost track of the optical disk.
The target track is the same track for the previous seek and this seek.

Therefore, in most cases, the re-seek performed after the focus is turned on is such that the moving speed of the sled is equal to or higher than the speed of the previous seek (the seek in which the pickup head protrudes outside the outermost track of the optical disk). Was done in For this reason, even in the re-seek, the wave number of the tracking error signal cannot be counted accurately, and it is highly possible that the pickup head jumps out of the outermost track of the optical disc again, so that the pickup head is moved to the target track. In some cases, the above-described re-seek and focus search are repeated many times. In the worst case, the above-described re-seek and focus search are repeated indefinitely.

An object of the present invention is to prevent a pickup head from jumping out of an outermost track of an optical disk in a seek for moving the pickup head to a target track, thereby moving the pickup head to a target track. An object of the present invention is to provide an optical disk device capable of shortening a time required for a seek to be moved.

[0019]

An optical disk device according to the present invention has the following arrangement to solve the above-mentioned problems.

(1) A pickup head for reading data recorded on concentric or spiral tracks formed on a recording surface of an optical disk, head moving means for moving the pickup head in a radial direction of the optical disk, Jump-out detection means for detecting that the pickup head has jumped out of the outermost track formed on the optical disc; and pick-up by the jump-out detection means during seek for moving the pickup head to a target track. When it is detected that the head has jumped out of the outermost track, the head moving means moves the pickup head toward the inner circumference of the optical disc to perform a focus search, and then moves the pickup head again to the target track. Do a reseek to move to Seek control means, the seek control means, during the re-seek, until the pickup head reaches the target track, the pickup head is less than the number of moving tracks in the seek jumped out of the outermost track It is a means to repeat seeking.

In this configuration, when the pickup head detects that the pickup head has jumped out of the outermost track of the optical disk during a seek for moving the pickup head to a target track, the pickup head is moved toward the inner circumference of the optical disk. To do a focus search,
After that, re-seek to move the pickup head to the target track again is performed.

In this re-seek, the seek control means moves the pickup head to the target track by repeating the seek less than the number of moving tracks in the seek in which the pickup head jumps out of the outermost track. Therefore, in the re-seek, the moving speed of the sled is lower than the moving speed of the sled in the seek in which the pickup head jumps out of the outermost track. For this reason, the wave number of the tracking error signal can be properly counted (missing is suppressed), and the pickup head can be prevented from jumping out of the outermost track of the optical disk. As a result, the time required for the seek for moving the pickup head to the target track can be reduced.

(2) When the seek control means detects that the pickup head has jumped out of the outermost track, a limit position at which the head moving means can return the pickup head to the inner circumferential side of the optical disk. This is a means for returning to the vicinity and performing the focus search.

In this configuration, the pickup head that has protruded outside the outermost track can be returned to the vicinity of the limit position where the pickup head can be returned toward the inner circumference side of the optical disk, so that the focus can be reliably turned on in the focus search performed thereafter.

(3) Track number storage means for storing the number of moving tracks in a seek that has detected that the pickup head has jumped out of the outermost track, and the seek control means includes the pickup head during the seek. Is a means for repeating seeks less than the number of tracks stored in the track number storage means until the track reaches the target track.

With this configuration, when the seek control unit performs a seek that is equal to or more than the number of moving tracks when the pickup head jumps out of the outermost track in a seek performed in the past, a seek less than the number of moving tracks is performed. By repeating, the pickup head is moved to the target track. Therefore, it is possible to prevent the pickup head from jumping out of the outermost track not only at the time of reseek but also at the time of normal seek, thereby improving the reliability of the apparatus main body.

(4) When it is detected that the pickup head has jumped out of the outermost track during the seek, the number of moving tracks stored in the track number storage means is determined by the number of moving tracks in the current seek. Update means for updating the information.

In this configuration, since the number of tracks stored in the track number storage means is updated, it is possible to more reliably prevent the pickup head from jumping out of the outermost track during normal seek.

[0029]

FIG. 1 is a block diagram showing a configuration of a main part of an optical disk apparatus according to an embodiment of the present invention. The optical disc device 1 of this embodiment includes a CD, an MD,
This is a device for reading data recorded on the optical disc 10 such as a DVD and writing data to the optical disc 10. A control unit 2 controls the operation of the main body.
Reference numeral 3 denotes a spindle motor for rotating the optical disk 10 set in the main body. Reference numeral 4 denotes a pickup head that irradiates the optical disk 10 with a light beam and detects reflected light from the optical disk 10. The pickup head 4 has a light projecting unit, four divided photodiodes, and an objective lens 4a.

The pickup head 4 is mounted on a sled 11 as shown in FIG. The sled 11 is configured to be movable in a radial direction of the optical disk 10 (a direction indicated by an arrow in FIG. 2) by a sled motor (not shown). The objective lens 4a of the pickup head 4 is attached to the holder 12. Holder 12 is thread 11
Are rotatably mounted on a rotation shaft provided at substantially the center of the. The direction of rotation of the holder 12 is the direction indicated by the arrow in FIG. The holder 12 is rotated by an actuator (not shown). The rotation of the holder 12 causes the lens 4a
Is moved in the radial direction of the optical disk 10. The holder 12 is also configured to be movable in the direction of the rotation axis of the spindle motor 3 for rotating the optical disk 10.
The focus can be set to 0 (the focus can be turned on).

Reference numeral 5 denotes a tracking driver which inputs control signals (kick signal, brake signal, tracking servo signal (TS signal), etc.) to the above-described actuator, and rotates the holder 12 with respect to the sled 11. With the rotation of the holder 12, the lens 4 a
Move in the radial direction.

Reference numeral 6 denotes input of a control signal (kick signal, brake signal, etc.) to the above-described sled motor,
1 is a thread driver for moving the optical disk 1 in the radial direction of the optical disk 10. As the sled 11 moves, the main body of the pickup head 4 moves in the radial direction of the optical disc 10.

Reference numeral 7 denotes a servo processor that inputs signals to the tracking driver 5 and the thread driver 6. Reference numeral 8 denotes an RF amplifier that generates a tracking error signal described later.

The pickup head 4 detects the reflected light of the light beam radiated from the light projecting unit onto the optical disk 10 by the split photodiode, and outputs the output of the split photodiode to the RF.
Input to the amplifier 8. The RF amplifier 8 generates a tracking error signal based on a signal (output of the divided photodiode) input from the pickup head 4. The tracking error signal generated here is input to the servo processor 7.

During reproduction, the RF amplifier 8 generates a reproduction signal based on the output of the divided photodiode. This reproduced signal is output from an output unit (not shown).
At the time of recording, the control unit 2 controls light emission of the light projecting unit of the pickup head 4 to write data on the optical disc 10. The details of the operations at the time of reproduction and at the time of recording are well known, and thus description thereof is omitted here.

The above-described tracking error signal is used as a signal indicating the amount of deviation between the center of the track formed on the optical disk 10 and the irradiation position of the light beam. The irradiation position of the light beam is a position facing the center of the lens 4a.

The servo processor 7 applies tracking servo when the track is on. To apply the tracking servo means to input a tracking servo signal generated based on the input tracking error signal to the tracking driver 5. The tracking driver 5 drives the actuator based on the input tracking servo signal to position the center of the lens 4a, that is, the irradiation position of the light beam, at the center of the track.

Hereinafter, seek control in the optical disk device 1 according to this embodiment will be described. As is well known, the optical disc 10 has a plurality of concentric or spiral tracks 21 formed on a recording surface. A mirror portion 22 is formed between adjacent tracks 21 (see FIG. 3). The mirror section 22 is a total reflection area. FIG. 3 is a diagram showing a cross section of the optical disk 10, and the lower surface is a recording surface. In the actual optical disc 10, the tracks 21 are formed more densely.

In the optical disk apparatus 1, when reading or writing data recorded on the optical disk 10,
A seek for moving the pickup head 4 (the irradiation position of the light beam) from the current position to the target track 21 is performed. Here, the target track 21 is a track 21 from which data is to be read or to which data is to be written. This seek includes a case involving movement of the sled 11 and a case involving only movement of the lens by the actuator. When the number of tracks for moving the pickup head 4 is equal to or greater than a preset number of tracks (for example, 100 or more), the movement of the sled 11 is accompanied. The set number of tracks is stored in a memory (not shown) provided in the control unit 2.

Further, the memory stores a speed table in which the number of tracks for moving the pickup head 4 and the moving speed of the sled 11 are associated with each other. In this speed table, as the number of tracks to be moved increases, the moving speed of the associated thread 11 increases. This is to reduce the time required for a seek with a large number of tracks for moving the pickup head 4.

Note that, instead of the above speed table, function data indicating the relationship between the number of moving tracks and the moving speed of the sled 11 may be stored in the memory. As the function data, for example, moving speed = number of moving tracks / A Note that A may be a constant or may be a variable that changes according to the number of moving tracks.

Further, in the memory, the number of tracks moved when the pickup head 4 jumps out of the outermost track 21 formed on the optical disk 10 in a seek performed in the past (hereinafter, this track number is referred to as a threshold track). Number) is stored.

FIGS. 4 and 5 are flowcharts showing seek control in the optical disk device according to the embodiment of the present invention. 6 to 8 are time charts of the seek control. The optical disk device 1 calculates the number of tracks from the current position of the pickup head 4 to the target track 21, that is, the number of tracks for moving the pickup head 4 (hereinafter referred to as the number of moving tracks) (s1). Then, it is determined whether or not the calculated number of moving tracks is equal to or larger than the set number of tracks accompanied by the movement of the sled 11 (s2).

If it is determined in s2 that the number is not equal to or larger than the set number of tracks (if it is determined that the seek does not involve the movement of the thread 11), the tracking servo is turned off (s3).
A drive kick signal is given to the actuator (s4). Thereafter, the process jumps to s15 described later.

On the other hand, if it is determined that the number of tracks is equal to or more than the set number of tracks (if it is determined that the seek involves the movement of the thread 11), the following processes of s5 to s14 are performed, and then the processes of s15 and thereafter are performed.

Next, the operation of s5 to s14 will be described. The optical disc device 1 determines whether or not the number of moving tracks calculated in s1 is less than the threshold track number (s
5). The threshold track number is the number of moving tracks required for a seek (failed seek) when the pickup head 4 jumps out of the outermost track 21 of the optical disk 10 in a seek performed in the past. The number of moving tracks is updated each time a seek fails.
Therefore, when a seek in which the number of moving tracks is equal to or greater than the threshold track number is performed, there is a high possibility that the pickup head 4 jumps out of the outermost track 21 of the optical disk 10 (the possibility of a seek failure).

When the optical disk device 10 determines that the number of tracks is not less than the threshold track number in s5 (determines that there is a high possibility of a seek failure), it jumps to s21 shown in FIG. The processing after s21 will be described later.

If it is determined in s5 that the number of tracks is less than the threshold track number (if it is determined that the possibility of a seek failure is low),
A drive kick signal to be given to the sled 11 is calculated based on the speed table stored in the memory of the control unit 2, and the calculated drive kick signal is given to the sled 11 (s6) (T1 shown in FIG. 6). ). The magnitude of the driving kick signal calculated here is a magnitude at which the moving speed of the sled 11 quickly reaches the speed corresponding to the number of moving tracks set in the speed table.

At s6, when the drive kick signal is given to the sled 11, the tracking servo is not turned off (the track is on), and the tracking driver 5 moves the center of the lens 4a to the track at the current position. The actuator is controlled so that it stays at the center. Although not shown in FIG. 6, the tracking error signal at this time is at a substantially constant level.

The sled 11 starts moving in the target track direction some time after the drive kick signal is given (T2 shown in FIG. 6). When the sled 11 starts moving in the target track direction, the pickup head 4 moves in the target track direction together with the sled 11. Therefore, the tracking servo signal given to the actuator by the tracking driver 5 gradually increases. Specifically, in the state shown in FIG. 9A, when a drive kick signal is given to the sled 11 and the sled 11 starts moving in the target track direction, the tracking servo is not turned off (the track is in the on state). Therefore, the tracking driver 5 controls the actuator so that the center of the lens 4a is kept at the center of the track where the lens is currently located (see FIG. 9B). Therefore, the tracking servo signal given to the actuator by the tracking driver 5 gradually increases.

When the tracking servo signal reaches a predetermined level set in advance (s7) (T shown in FIG. 6).
3) Turn off the tracking servo and supply a drive kick signal to the actuator (s8, s9). Further, the drive kick signal to the sled 11 is stopped (s10). The actuator is supplied with a drive kick signal of a predetermined magnitude that is predetermined for a predetermined time. Thereafter (after T4 shown in FIG. 6), an acceleration kick and a deceleration kick are given to the sled 11 and the actuator to control the moving speed in the target track direction at a constant speed (s11). This constant velocity control determines whether the pickup head 4 is in a focus off state (the pickup head 4
Does not jump out of the outermost track formed on the optical disc 10) or until the pickup head 4 is detected to have moved to a position less than the set number of tracks with respect to the target track (s12, s1
3).

In s11, the actuator is set to the thread 1
1 is controlled at a reference position (see FIG. 9 (C)), and the moving speed of the lens 4a in the target track direction becomes uniform. Here, the moving speed of the lens 4a is a speed corresponding to the number of moving tracks set in the speed table.

Here, constant speed control of the thread 11 will be described with reference to FIG. Servo processor 7
By detecting the period of the tracking error signal input from the RF amplifier 8, the moving speed of the sled 11 can be detected. The tracking error signal is
This is a sinusoidal signal output every time the center of a crosses the track 21. The cycle of the tracking error signal changes according to the moving speed. Specifically, as the moving speed of the lens 4a increases, the period of the tracking error signal decreases, and conversely, as the moving speed of the lens 4a decreases, the period of the tracking error signal increases.

The servo processor 7 controls the tracking driver 5 and the thread driver 6 so that the period of the tracking error signal (T11 to T19 shown in FIG. 7) becomes a period corresponding to the moving speed set in the speed table.
Input an acceleration kick or a deceleration kick as a servo signal. The tracking driver 5 and the sled driver 6 control the moving speed of the lens 4a based on the input acceleration kick or deceleration kick. The optical disk device 1 detects the number of tracks that the pickup head 4 (lens 4) has traversed by counting the number of waves of the tracking error signal.

As described above, the tracking servo is turned off at the timing when the sled 11 moves by a predetermined amount, and the movement control of the actuator is started. Therefore, when the sled 11 is displaced or when the sled 11 is moved. The actuator can be moved at the timing when the sled 11 has moved by a predetermined amount without being affected by variations in frictional force or the like generated in the above. Therefore, the balance between the sled 11 and the actuator can always be stabilized.

In a past seek in which the moving speed of the sled 11 was lower than the moving speed of the sled 11 controlled in s11, the pickup head 4 was moved outside the outermost track of the optical disc 10 due to the missing tracking error signal. Never jumped out. Therefore, in the processing of s11 to s13, the pickup head 4 jumps out of the outermost track of the optical disk 10 in s12, and is less likely to focus off (the possibility of seeking failure is low).

When the optical disk device 1 detects that the focus is turned off in s12, the process proceeds to s41 shown in FIG. 5B, and in s13, the pickup head reaches a position less than the set number of tracks with respect to the target track. When it is detected that 4 has moved (ta shown in FIG. 7), the brake is applied to the sled 11 (s14). Thereafter, the actuator is controlled to perform constant speed control until the lens 4a reaches 1/2 track before the target track (s1).
5, s16).

At this time, the RF amplifier 8 is inputting the tracking error signal generated based on the input from the pickup head 4 to the servo processor 7. The servo processor 7 causes the actuator to move the lens 4a at a preset constant speed until the center of the lens 4a reaches 1/2 track before the target track.

As shown in FIG. 8, the constant speed control according to s15 is performed so that the period (T21 to T27) of the tracking error signal input from the RF amplifier 8 becomes a predetermined period. Is a control for giving an acceleration kick or a deceleration kick to the motor. When it is determined that the number of tracks is less than the set track number in s2, and the processes in s3 and s4 are performed, the processes in and after s15 are also performed.

The center of the lens 4a is set at 1 / the target track.
When two tracks are approached (tb shown in FIG. 8), a brake is applied to the tracking driver 5 to stop the movement of the lens 4a by the actuator (s17). The servo processor 7 controls the amount of braking according to the moving speed of the lens 4a when crossing the immediately preceding track. Specifically, in the tracking error signal input from the RF amplifier 8, the cycle of the sine wave generated when the signal traverses the immediately preceding track, T2 in FIG.
7, the brake amount is controlled.

The braking amount may be controlled by either the braking time t or the magnitude V of the brake, or by both.

When the application of the brake signal is completed, the servo processor 7 waits until the level of the tracking error signal input from the RF amplifier 8 drops below a preset threshold SH (s18).

At this time, the lens 4a is not completely stopped, but is moving in the target track direction at a speed close to zero.

When the level of the tracking error signal falls below the threshold SH, the servo processor 7 applies tracking servo (s19).

As shown in FIG.
H is set to a level at which the center of the lens 4a is located on the C track. Further, the servo processor 7 does not apply an acceleration kick or a deceleration kick to the tracking driver 5 during a period from the timing tc at which the braking is completed to a timing td at which the level of the tracking error signal falls below the threshold SH.

Therefore, when the center of the lens 4a is located at the target track (track C), the tracking servo can be applied to turn on the track.

In the above description, when the level of the tracking error signal falls below the threshold SH, the tracking servo is applied and the track is turned on. However, the level of the tracking error signal is set within a preset range. Further, when the level of the tracking error signal is lowered, the tracking servo may be performed to turn on the track.

When the servo servo is applied, the servo processor 7 outputs a focus servo signal to adjust the focus of the lens 4a. The focus can be adjusted by moving the lens 4a in the rotation axis direction of the actuator by a focusing actuator (not shown).

As described above, the optical disc apparatus 1 of this embodiment can be driven with respect to the sled 11 without being affected by the dispersion of the components constituting the sled 11 and the frictional force generated when the sled 11 is moved. The balance between the movement of the sled 11 and the movement of the lens 4a by the actuator when the kick signal is stopped can be stabilized.

When the brake amount applied to the actuator for stopping the center of the lens 4a on the target track 21 is adjusted to a magnitude corresponding to the moving speed of the lens 4a immediately before, and the brake is applied. Instead of immediately applying the tracking servo to turn on the track, the track is turned on after the center of the lens 4a is positioned on the target track. For this reason, when the center of the lens 4a is located at the mirror portion 22, the tracking servo is not performed to turn on the track, so that the occurrence of track slippage can be prevented, and the reliability of the apparatus main body can be improved.

Next, FIG. 5 shows a case where it is determined in s5 that the number of moving tracks is equal to or larger than the threshold track number.
This will be described with reference to FIG. In this case, in the past seek in which the moving speed of the thread 11 was lower than the speed corresponding to the number of moving tracks (the speed obtained from the speed table), the optical disc apparatus 1 caused the pickup head 4 to lose the optical disc due to the missing tracking error signal. 10 jumped out of the outermost track and failed in seeking.

The optical disc apparatus 1 calculates the number of tracks by multiplying the threshold track number stored in the memory by a preset constant B as the number of moving tracks (s2).
1). This constant B is a number less than one. For example, 0.9
It is. Then, the same processes as those in s6 to s14 described above are executed (s22 to s30).

The number of moving tracks calculated in the above s21 is smaller than the threshold track number stored in the memory because the constant B is a number less than 1. Therefore, the moving speed of the sled 11 controlled in s27 is lower than the moving speed of the sled 11 in a seek that has failed in the past. For this reason, in the processing of s27 to s29 corresponding to the above s11 to s13, the pickup head 4 jumps out of the outermost track 21 of the optical disc 10 due to the missing tracking error signal,
Less likely to fail seek.

When the pickup head reaches a position less than the set track number in s29 (when the number of moving tracks of the pickup head 4 exceeds the number of moving tracks calculated in s21-the set track number), ), When the brake is applied to the sled motor in s30,
Immediately brake the actuator (s3
1). Then, it waits until the level of the tracking error signal input from the RF amplifier 8 falls below the preset threshold SH (s32), and the level of the tracking error signal is reduced to the threshold S.
When it falls below H, the tracking servo is applied (s3
3).

In the processing shown in FIG.
Since steps 5 and s16 are not executed, there is a high possibility that the pickup head 4 has not moved the number of moving tracks calculated in s21. However, when the pickup head 4 is moved by the number of moving tracks calculated in s21 in the processing shown in FIG. 5A, the pickup head 4 is not necessarily positioned on the target track (track on the target track 21). Not.)

The steps s15 and s16 take a relatively long time.

In the optical disk device 1 of this embodiment, since the pickup head 4 is not located at the target track at the time when the process of s33 is completed, the process returns to s1 and repeats the above process.

Therefore, s15 and s16 shown in FIG.
There is no particular problem even if the step corresponding to is omitted. Conversely, by not performing the processes of s15 and s16, there is an effect that the processing time can be reduced.

As described above, in the optical disk device 1 of this embodiment, the pickup head 4 repeats the seek less than the number of moving tracks in the seek protruding out of the outermost track, thereby moving the pickup head 4 to the target track. Move. Therefore, it is possible to almost certainly prevent the pickup head 4 from jumping out of the outermost track at the time of seeking (sufficient possibility of seeking failure), and as a result, the time required for seeking. Can be shortened.

In step s12 or s28, the pickup head 4 is moved to the outermost track 2 of the optical disk 10.
When the focus jumps out of 1 and the focus is turned off, the processing shown in FIG. 5B is executed, and the process returns to s1. The cause of the focus-off is a missing tracking error signal. First, the optical disc apparatus 1
The pickup head 4 projecting out of the outermost track 21 of the optical disk 10 is moved to the innermost track 21 of the optical disk 10.
It returns to the vicinity (s41). In s41, the optical disk 10
The pick head 4 is returned to the vicinity of a position where the pick head 4 can be mechanically returned to the inside. This allows the pickup head 4 to reliably face the track 21 formed on the optical disc 10.

Next, the optical disk device 1 performs a focus search (s42). As described above, since the pickup head 4 is positioned inside the optical disc 10 in s41, the possibility that the focus search performed in s42 fails is extremely low. The optical disk device 1
When the focus is turned on by the focus search performed in step S42 (s43), the threshold track number stored in the memory is updated to the number of moving tracks in the seek that failed this time (s44), and the process returns to s1.

As described above, the optical disk apparatus 1 of this embodiment updates the threshold track number at s44, and thus, in the seek executed in the past, the pickup head 4 loses the tracking error signal due to the missing tracking error signal.
Since the seek is not performed at a speed higher than the moving speed of the thread 11 in the failed seek that has jumped out of the outermost track 21 of 0, the possibility of the seek failure can be sufficiently suppressed. Thereby, the time required for the seek can be reduced, and the reliability of the apparatus main body can be improved.

One of the causes of missing in the counting of the tracking error signal is the influence of the individual difference of the optical disk 10. Therefore, the threshold track number is reset when the optical disk 10 is replaced. Is also good.

[0084]

As described above, according to the present invention, in the reseek, the moving speed of the thread is set to be lower than the moving speed of the thread in the failed seek, so that the reseek failure can be sufficiently prevented. Thereby, the time required for the seek can be reduced, and the reliability of the apparatus main body can be improved.

Also, when a new seek is performed, the speed of movement of the thread is lower than the speed of the thread in the past failed seek, so that the failure of the new seek can be sufficiently prevented. Therefore, the reliability of the apparatus main body can be further improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a main part of an optical disk device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a thread and a holder on which a pickup head of the optical disc apparatus according to the embodiment of the present invention is mounted.

FIG. 3 is a diagram showing a cross section of an optical disc.

FIG. 4 is a flowchart showing seek control of the optical disc device according to the embodiment of the present invention.

FIG. 5 is a flowchart showing seek control of the optical disc device according to the embodiment of the present invention.

FIG. 6 is a timing chart showing control of a sled and an actuator at the time of a track jump of the optical disc device according to the embodiment of the present invention.

FIG. 7 is a timing chart showing control of a sled and an actuator at the time of a track jump of the optical disc device according to the embodiment of the present invention.

FIG. 8 is a timing chart showing control of a sled and an actuator at the time of a track jump of the optical disc apparatus according to the embodiment of the present invention.

FIG. 9 is a diagram showing movements of a sled and an actuator of the optical disc device according to the embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1-optical disk drive 2-controller 4-pickup head 4a-objective lens 5-tracking driver 6-thread driver 7-servo processor 8-RF amplifier 10-optical disk 11-thread 12-holder 21-track 22-mirror unit

Claims (5)

[Claims] 1. A pickup head for reading data recorded on concentric or spiral tracks formed on a recording surface of an optical disc, a head moving means for moving the pickup head in a radial direction of the optical disc, Jump-out detection means for detecting that the pickup head has jumped out of the outermost track formed on the optical disc; and, at the time of seek for moving the pickup head to a target track, the pickup head by the jump-out detection means. When it is detected that the pickup head has jumped out of the outermost track, the head moving means moves the pickup head to near the limit position where the pickup head can return in the inner circumference direction of the optical disc, and then performs a focus search. Move to the target track again Seek control means for performing re-seek to move, and when detecting that the pickup head has jumped out of the outermost track during the seek, track number storage means for updatingly storing the number of moving tracks in the seek. The seek control means repeats a seek less than the number of moving tracks in a seek in which the pickup head jumps out of the outermost track until the pickup head reaches a target track during the reseek, An optical disc device which is means for repeating a seek less than the number of tracks stored in the track number storage means until the pickup head reaches a target track during a seek. 2. A pickup head for reading data recorded on concentric or spiral tracks formed on a recording surface of an optical disc, a head moving means for moving the pickup head in a radial direction of the optical disc, Jump-out detection means for detecting that the pickup head has jumped out of the outermost track formed on the optical disc; and, at the time of seek for moving the pickup head to a target track, the pickup head by the jump-out detection means. When it is detected that the optical disc jumps out of the outermost track, the head moving means moves the pickup head toward the inner circumference side of the optical disc to perform a focus search, and then moves the pickup head to the target track again. Sea to re-seek to move A seek control unit, wherein the seek control unit performs a seek operation less than the number of moving tracks in a seek in which the pickup head jumps out of an outermost track until the pickup head reaches a target track during the reseek. Optical disk device which is means for repeating the above. 3. The seek control means, when detecting that the pickup head has jumped out of the outermost track, near a limit position at which the head moving means can return the pickup head to the inner circumferential side of the optical disk. 3. The optical disk device according to claim 2, wherein the optical disk device is a means for performing the focus search by returning the optical disk to the optical disk. 4. A seek number storage means for storing the number of moving tracks in a seek that has detected that the pickup head has jumped out of an outermost track, wherein the seek control means is configured to control the pickup head during the seek. 4. The optical disk device according to claim 2, wherein the seek unit repeats a seek less than the number of tracks stored in the track number storage unit until reaching a target track. 5. When the pickup head detects that the pickup head has jumped out of the outermost track during the seek, the number of moving tracks stored in the track number storage means is changed to the number of moving tracks in the current seek. 5. The optical disk device according to claim 4, further comprising an updating unit for updating.