JP2000215485A - Optical disk drive device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform stable tracking operation by switching the polarity of a tracking error signal at the suitable timing. SOLUTION: When it is indicated that an address decode signal S41a is normal, a reference value stored in a reference value storage circuit 37 is updated by a rotation angle indicated by a rotation angle signal S31 on a switching position between a land and a groove fetched to a capture circuit 35. Further, an interpolation value for a track radius is obtained from a difference between angular reference values of an innermost peripheral track and an outermost peripheral track by a reference value interpolation circuit 50, and the reference value of the reference value storage circuit 37 is interpolated. Then, the reference value interpolated by the reference value interpolation circuit 50 is compared with the rotation angle indicated by the rotation angle signal S31 by a comparator circuit 32, and when they agree, a switching signal S29 for switching the polarity of the tracking error signal is generated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an optical disk drive capable of driving an optical disk by stably generating an appropriate tracking error signal.

[0002]

2. Description of the Related Art Conventionally, DVD-RAM (Digital Ve
2. Description of the Related Art A recordable and reproducible optical disk such as an rsatile disk (random access memory) is known. Among such optical disks, there is one that adopts, for example, a land / groove method as a disk format. In this case, in order to record and reproduce arbitrary information on the recording surface of the optical disk, there are provided a data area in which only guide grooves are generated, and an address area in which absolute position information in the disk is recorded in bits. The land-groove type disk format is roughly classified into a double spiral format and a single spiral format. In the double spiral format, individual land tracks and groove tracks are provided adjacent to each other. Also, the single spiral format is one of the discs.
The land track and the groove track are switched every circumference, forming one track as a whole.

[0003] A tracking servo of a conventional recording / reproducing apparatus for recording / reproducing a single spiral format DVD-RAM will be described below. FIG.
FIG. 2 is a block diagram illustrating a configuration of a conventional optical disk drive 1 that realizes a function related to tracking servo of a DVD-RAM recording / reproducing apparatus. As shown in FIG. 7, in the optical disk drive 1, the DVD-RAM disk 2 is driven to rotate by the spindle motor 15, and the laser beam from the laser device 3 is emitted by the tracking coil 4 on the recording surface of the DVD-RAM disk 2. The controlled position is irradiated via the objective lens, and the returned light (reflected light) forms an image on the light receiving element 5. In the light receiving element 5, a DVD-RAM
The return light from the disk 2 is converted into a tracking error signal S5A indicating a tracking shift and a sum signal S5B indicating the amount of return light, and output to the A / D converters 6 and 7, respectively.

The A / D converters 6 and 7 convert the tracking error signal S5A and the sum signal S5B into digital tracking error signals S6 and sum signals S7, respectively.
And these are output to the normal processor 8. The normalization processor 8 performs a normalization process based on the sum signal S7 so that the level of the tracking error signal S6 does not change, and outputs the normalized tracking error signal S8 to the polarity switching device 9.

On the other hand, the address S5C read from the DVD-RAM disk 2 is output from the light receiving element 5 to the raster sector detection circuit 13, and the last sector detection circuit 13 immediately before the land and groove are switched based on the address S5C. A last sector signal S13 indicating a sector is detected. Next, the one-sector delay circuit 14
, The last sector signal S13 is delayed by a time corresponding to one sector to become a polarity switching signal S14, which is output to the polarity switching device 9. In the polarity switching device 9, based on the polarity switching signal S14, the polarity of the tracking error signal S8 is inverted as necessary, and the tracking error signal S9 whose polarity is controlled is generated.
This tracking error signal S9 is output to the phase compensation digital filter 10.

The reason why the polarity of the tracking error signal S8 needs to be controlled in this way is that the polarity of the tracking error signal is reversed when tracing a land and when tracing a groove. . The tracking error signal S9 is the phase compensation digital filter 1
At 0, the signal is phase-compensated, converted to an analog signal by the D / A converter 11, and a drive signal S11 is generated. After the drive signal S11 is amplified by the drive amplifier 12, the tracking coil 4
And the tracking coil 4 is driven.

[0007]

However, in the above-mentioned conventional optical disk drive 1, for example, a DVD-RAM
The polarity switching may occur due to dust or the like not adhering to the recording surface of the disk 2 to detect the last sector, or when the speed of the spindle motor 15 is not stable when starting track tracing after performing a seek operation. There is a problem that the signal S14 is not generated properly and the tracking servo becomes unstable.

The applicant of the present invention uses a signal synchronized with the rotation of the spindle motor to generate an RF (last sector) signal.
An optical disk drive that can generate a polarity switching signal with accurate timing even when a signal cannot be detected or when the spindle rotation is changing has been proposed (Japanese Patent Application No. Hei 10 (1998) -108).
-086756). That is, this optical disk drive generates a rotation angle signal of the optical disk based on an FG signal corresponding to the rotation of the optical disk or a signal from the Hall element, and compares the rotation angle signal with a previously stored rotation angle reference value. By detecting the coincidence, a polarity switching signal of an appropriate tracking error signal is generated. By the way, such a configuration is based on the premise that there is no displacement between the moving straight line of the light spot by the optical pickup feed mechanism and the rotation center of the optical disk.

However, in an actual apparatus, the movement straight line of the light spot and the rotation center of the optical disk have a certain positional deviation due to a mechanical error or the like. Therefore, the rotation angle reference value used in the above configuration is It changes depending on the radius of the track being tracked, and cannot be an optimal timing switching signal for all tracks. Note that the amount of deviation between the light spot movement straight line and the center of rotation of the disk is approximately 0.5 in the example shown in FIG.
The deviation of the rotation angle reference value between the inner and outer peripheries (r = 30.55) of the recording / reproducing area of an optical disc having a diameter of about 5 mm and a diameter of 120 mm is 0.43 ° in angle, for example, a DVD-RAM format. In the case of (1), it deviates from the land / groove switching area.

Accordingly, an object of the present invention is to provide a configuration in which a polarity switching signal of a tracking error signal is generated in accordance with the rotation angle of an optical disk. An object of the present invention is to provide an optical disk drive capable of removing an error and obtaining a proper polarity switching operation.

[0011]

SUMMARY OF THE INVENTION In order to achieve the above object, according to the present invention, a tracking servo is performed on an optical disk having a recording track of a single spiral format in which lands and grooves are alternately arranged for each rotation. An optical disk drive for switching the polarity of a tracking error signal in accordance with the switching position of the groove and the groove, wherein the rotation angle of the optical disk is determined based on a rotation signal corresponding to the rotation of the optical disk input from a drive unit for driving the rotation of the optical disk A rotation angle generating means for generating, a first detecting means for detecting a position at which a land and a groove are switched based on an address signal read from the optical disk, and a detecting means for detecting a position at which the land and the groove are switched. The rotation angle generated by the rotation angle generation means at a corresponding timing. Rotation angle specifying means for specifying an angle, reference value storage means for storing a reference value to be compared with the rotation angle generated by the rotation angle generating means, and when the address signal is correct, the rotation angle specifying means Reference value setting means for updating the reference value stored in the reference value storage means at the specified rotation angle; and second detection means for detecting a radius of a track being tracked based on a track signal read from the optical disc. Detecting means;
Reference value interpolation means for interpolating the reference value stored in the reference value storage means based on the radius of the track detected by the detection means, and the rotation angle and the reference value generated by the rotation angle generation means. A comparison unit that compares a reference value interpolated by the interpolation unit and generates a polarity switching signal of the tracking error signal when the two match, and a polarity of the tracking error signal is determined by the polarity switching signal generated by the comparison unit. Switching means for switching the polarity, and servo control means for performing tracking servo control of the optical disk by the optical pickup based on an output signal from the polarity switching means. The rotation center of the optical disk and the optical pickup are controlled by the reference value interpolation means. Polarity cut due to deviation of the relative position of the light spot movement straight line due to Characterized in that to compensate for the timing error e signal.

In this optical disk drive, the reference value stored in the reference value storage means, which is appropriately updated by the reference value setting means, is interpolated by the reference value interpolation means in correspondence with the track radius. The rotation angle generated by the generation unit is compared by the comparison unit, and when they match, a polarity switching signal of the tracking error signal is generated. The polarity of the tracking error signal is switched by the polarity switching means in accordance with the polarity switching signal, and tracking servo control of the optical disk by the optical pickup is performed based on the output signal from the polarity switching means. As described above, in the configuration in which the polarity switching signal of the tracking error signal is generated in accordance with the rotation angle of the optical disc, the error of the polarity switching timing due to the deviation between the moving straight line of the light spot by the optical pickup and the center of the optical disc is determined by the reference value interpolation means. And an appropriate polarity switching operation can be obtained.

Further, according to the present invention, during the execution of tracking servo for an optical disk having a recording track of a single spiral format in which lands and grooves are alternately arranged for each revolution, a tracking error signal is generated in accordance with the switching position of the lands and grooves. An optical disk drive that switches the polarity of the optical disk, a rotation angle generating unit that generates a rotation angle of the optical disk based on a rotation signal corresponding to the rotation of the optical disk input from a driving unit that drives the rotation of the optical disk; Detecting means for detecting a position at which the land and the groove are switched based on the read address signal; and the rotation generated by the rotation angle generating means at a timing corresponding to the detection of the position at which the land and the groove are switched. Rotation angle specifying means for specifying an angle; A reference value storing means for storing a reference value which is rolling angle generating unit is compared with the rotational angle generated,
When the address signal is correct, a reference value setting unit that updates a reference value stored in the reference value storage unit with the rotation angle specified by the rotation angle specifying unit; and the rotation generated by the rotation angle generation unit. Comparing the angle with the reference value stored in the reference value storage means, and when the two coincide with each other, generating a polarity switching signal of a tracking error signal; and performing tracking by the polarity switching signal generated by the comparison means. Polarity switching means for switching the polarity of the error signal; servo control means for performing tracking servo control of the optical disk by the optical pickup based on the output signal from the polarity switching means; Adjusting means for mechanically adjusting the amount of displacement of the rotation center. To.

In this optical disk drive, the deviation between the moving straight line of the light spot by the optical pickup and the center of rotation of the optical disk is mechanically adjusted in advance by adjusting means.
The moving straight line of the light spot coincides with the radial direction of the optical disk. Then, the reference value of the reference value storage means, which is appropriately updated by the reference value setting means, and the rotation angle generated by the rotation angle generation means are compared by the comparison means. When the two coincide, the polarity switching signal of the tracking error signal is output. Is generated. Here, the reference value set by the reference value setting means is uniform irrespective of the radius of the track because the moving straight line of the light spot coincides with the radial direction of the optical disk. The polarity of the tracking error signal is switched by the polarity switching means in accordance with the polarity switching signal, and tracking servo control of the optical disk by the optical pickup is performed based on the output signal from the polarity switching means. As described above, in the configuration in which the polarity switching signal of the tracking error signal is generated in accordance with the rotation angle of the optical disk, the error of the polarity switching timing due to the deviation between the moving straight line of the light spot by the optical pickup and the center of the optical disk is previously determined by mechanical. It can be removed by the adjusting means, and an appropriate polarity switching operation can be obtained.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an optical disk drive according to the present invention will be described below. In this embodiment, a single spiral format DVD-RAM
An optical disk drive provided in a recording / reproducing device for recording and reproducing data will be described. The optical disk drive according to the present embodiment is characterized by tracking servo. FIG. 1 shows a DVD-ROM according to the present embodiment.
FIG. 2 is a block diagram illustrating a configuration of an optical disk drive device 21 that realizes a function related to tracking servo of a recording / reproducing device of a RAM.

The optical disk drive 21 performs tracking servo of the single spiral format DVD-RAM disk 2 by controlling the rotation of the disk 2 by the spindle motor 15 and the tracking control by the optical pickup 22. As shown in FIG. 1, the optical disk drive 21 includes a polarity switching signal generation circuit 29, a digital signal processing circuit 19, a spindle control unit 40, an address decoding unit 41, and the tracking coil 4. The spindle control unit 40 generates a spindle drive signal S40A, outputs this to the spindle motor 15, and outputs an FG signal shown in FIG. 2A from a frequency generator (not shown) provided in the spindle motor 15. Based on the cycle of S15, a spindle lock signal S40B indicating whether the spindle motor 15 is stable at the target rotational speed, that is, whether the spindle motor 15 is in the locked state, is generated. Output to

The address decoding section 41 receives the address signal S5C based on the RF signal S5C input from the light receiving element 5.
41B, and outputs it to the last sector detection circuit 13. In addition, the address decoding unit 41 includes the light receiving element 5
A track signal S41C is generated based on the RF signal S5C input from the
9 to the reference value storage circuit 37 and the reference value interpolation circuit 50. Further, the address decode unit 41 generates an address decode error signal S41A read based on the RF signal S5C input from the light receiving element 5, and outputs this to the reference value setting circuit 36 of the polarity switching signal generation circuit 29.

The digital signal processing circuit 19 has basically the same configuration as the digital signal processing circuit of the optical disk drive 1 shown in FIG. That is, the digital signal processing circuit 19 includes the A / D converters 6 and 7, the normal processor 8, the polarity switcher 9, the phase compensation digital filter 1
0 and a D / A converter 11. A / D converter 6
Converts the analog tracking error signal S5A from the light receiving element 5 into a digital tracking error signal S6, and converts the tracking error signal S6 into the normal processor 8
Output to The A / D converter 7 converts the analog sum signal S5B from the light receiving element 5 into a digital sum signal S7, and outputs this sum signal S7 to the normal processor 8.

The normalization processor 8 performs a normalization process based on the sum signal S7 so that the level of the tracking error signal S6 does not change, and outputs the normalized tracking error signal S8 to the polarity switching device 9. The polarity switch 9 inverts the polarity of the tracking error signal S8 as needed based on the polarity switching signal S29, and generates the tracking error signal S9. This tracking error signal S9 is output to the phase compensation digital filter 10. The phase compensation digital filter 10 performs phase compensation of the tracking error signal S9, and outputs the phase-compensated tracking error signal S10 to the D / A converter 11. The D / A converter 11 converts the tracking error signal S10 into an analog tracking error signal S11, and outputs the tracking error signal S11 to the drive amplifier 12.

The polarity switching signal generation circuit 29
PLL circuit 30, rotation angle counter circuit 31, comparator circuit 32, capture circuit 35, reference value setting circuit 3
6, a reference value storage circuit 37, a reference value interpolation circuit 50, a last sector detection circuit 13, and a one-sector delay circuit 14. Last sector detection circuit 13 and one-sector delay circuit 14
Are the same as the last sector detection circuit 13 and the one-sector delay circuit 14 of the conventional optical disk drive 1 shown in FIG. The last sector detection circuit 13 generates a last sector signal S13 indicating that the sector is immediately before the land and groove are switched based on the address signal S41b input from the address decoding unit 41, and sends this to the one-sector delay circuit 14. Output. One-sector delay circuit 14
Delays the last sector signal S13 by a time corresponding to one sector, and outputs the last sector detection signal S14 shown in FIG.
A is generated and output to the capture circuit 35.

The PLL circuit 30 includes a spindle motor 15
After performing PLL processing on the FG signal S15 shown in FIG. 2A input from the FG signal S1 shown in FIG.
It outputs to the rotation angle counter circuit 31 as 30. The rotation angle counter circuit 31 counts the pulses included in the FG signal S30, generates a rotation angle signal S31 indicating the rotation angle of the disc 2 as shown in FIG. 32. The capture circuit 35 captures the rotation angle value indicated by the rotation angle signal S31 from the rotation angle counter circuit 31 according to the timing at which the raster sector is reproduced, based on the raster sector signal S14A from the one-sector delay circuit 14. a1 Generates a polarity switching signal S14 and outputs it to the polarity switching device 9.

The reference value setting circuit 36 functionally determines whether or not the rotation angle value captured by the capture circuit 35 is a correct value. Only when it is determined that the rotation angle value is correct, the reference value storage circuit 37 Update the stored reference value. Specifically, the reference value setting circuit 36 outputs the spindle lock signal S4
When 0B indicates the locked state and the address decode error signal S41A indicates that no error has occurred, the rotation angle value captured by the capture circuit 35 is read as a valid value, and the read rotation angle value and ,
The average value with a plurality of rotation angle values read in the past from the capture circuit 35 is calculated, and the reference value already stored in the reference value storage circuit 37 is updated using this average value as a new reference value. As described above, the average value of the rotation angle values is obtained by the capture circuit 35, so that the capture circuit 35
The reference value stored in the reference value storage circuit 37 can be made stable even when the rotation angle value taken into the storage device slightly increases or decreases.

The reference value interpolating circuit 50 is based on the track signal S41C input from the address decoding unit 41,
It interpolates the rotation angle reference value stored in the reference value storage circuit 37, and functions as a means for compensating a timing error of a polarity switching signal due to a relative positional deviation between a recording track of the disk 2 and a light spot of the optical pickup 22. I do. In particular, in this example, the deviation amount between the light spot movement straight line and the rotation center of the optical disk is obtained from the timing deviation amount between the innermost track and the outermost track of the optical disk, and the radius of the track being tracked according to this deviation amount. The interpolation of the polarity switching signal corresponding to the above is performed. Hereinafter, the operation of interpolating the reference value by the reference value interpolation circuit 50 will be described in detail.

In general, in this type of optical disk drive, an optical pickup 22 is transported along a feed axis (feed screw or the like) installed in the apparatus main body in a radial direction of the optical disk to perform tracking servo of an optical spot. In this case, the moving straight line of the optical pickup 22 (that is, the light spot) is moved with respect to the rotation center of the optical disk (that is, the recording track).
There is a certain deviation due to a mechanical assembly error or the like. Therefore, as shown in FIG. 4, the above-described rotation angle reference value changes according to the radius of the track, and cannot be a polarity switching signal at an appropriate timing for each radius. Therefore, in this embodiment, the polarity switching signal at an appropriate timing is obtained by interpolating the rotation angle reference value according to the radius of the track being tracked by the reference value interpolation circuit 50.

In this example, first, the amount of deviation between the light spot movement straight line and the center of rotation of the optical disk is determined from the amount of timing deviation between the innermost track and the outermost track of the optical disk 2. That is, in this operation, the optical pickup is moved within the recording / reproducing area of the optical disk 2, and the rotation angle reference value is set at the positions of the innermost track and the outermost track. At this time, if there is a deviation between the moving straight line of the light spot and the rotation center of the disk 2, the rotation reference values at the inner circumference and the outer circumference are different.

FIG. 4 is a plan view of an optical disk showing the example. That is, in FIG. 4, when the relative displacement between the light spot movement straight line and the rotation center of the optical disk is d, the rotation angle reference value of the innermost track (zone 0) is set to θin, and the outermost track (zone The rotation angle reference value of 26) is shown as θout. On the other hand, since the radii of the innermost track and the outermost track are known in advance,
Knowing these θin and θout, conversely, the shift amount d
Can be requested. By knowing the deviation d, the interpolation value θr of the rotation angle reference value at an arbitrary radius r is obtained.
Can be set as θr = sin ⁻¹ (d / r). That is, by calculating the relative displacement between the light spot movement straight line and the rotation center of the optical disc 2 from the difference between the rotation angle reference values of the inner circumference and the outer circumference, the rotation angle reference value at an arbitrary radius is interpolated with the interpolation value θr. Can be.

When the light spot is moving slowly on the adjacent track, the change in the error of the angle reference value due to the change in the track radius is small. It is possible to obtain However, when the light spot moves rapidly between the separated tracks, the change in the error of the angle reference value due to the change in the track radius becomes large. An error of the angle reference value due to the change is eliminated, and a proper operation timing is secured.

The reference value interpolation circuit 50 detects the radius of the track being tracked on the basis of the track signal S41C input from the address decoding unit 41 according to the principle described above, and according to the radius, stores the reference value storage circuit. 37
Interpolation of the rotation reference value stored in the comparator circuit 3
Feed to 2. The comparator circuit 32 stores the rotation angle value indicated by the rotation angle signal S31 from the rotation angle counter circuit 31 and the reference value storage circuit 37 into the reference value interpolation circuit 5.
The reference value interpolated by 0 is compared with the reference value, and when they match, a pulse is generated, a polarity switching signal S29 as shown in FIG.

Next, the operation of the above optical disk drive will be described. Here, mainly the operation of the polarity switching signal generation circuit 29 will be mainly described,
1 will be described separately when the address is properly decoded and when it is not.

(1) When Address Decoding is Correctly Performed In this case, the RF signal S according to the reproduction result of the disk 2
The address read from the disk 2 is correctly decoded by the address decoding unit 41 based on 5C, and a valid address signal S41B is output to the last sector detection circuit 13. Further, an address decode signal S41A indicating that decoding has been correctly performed is output to the reference value setting circuit 36. Then, the last sector detection circuit 13 generates a last sector signal S13 indicating that the sector is immediately before the land and groove are switched based on the address signal S41B, and outputs the last sector signal S13 to the one-sector delay circuit 14. You. The last sector signal S13 is output from the one-sector delay circuit 14 as 1
A last sector signal S1 that is delayed by a time corresponding to a sector and generates a pulse at timing A shown in FIG.
4A is output to the capture circuit 35. The capture circuit 35 captures the rotation angle value indicated by the rotation angle signal S31 at a timing corresponding to the last sector indicated by the last sector signal S14A.

On the other hand, in the reference value setting circuit 36, the spindle lock signal S40B indicates the locked state, and the address decode error signal S41A indicates that the decoding is correctly performed. The reference value stored in the reference value storage circuit 37 is updated using the new reference value that is the average value calculated using the reference value. Further, the reference value is interpolated by the reference value interpolation circuit 50 according to the radius of the track being tracked. Thereafter, in the comparator circuit 32, the reference value interpolated by the reference value interpolation circuit 50 is compared with the rotation angle value indicated by the rotation angle signal S31, and when they match, that is, at the timing B shown in FIG. The polarity switching signal S29 is switched.

(2) When an error occurs in the decoding of the address In this case, the address decoding unit 41 decodes the address read from the disk 2 based on the RF signal S5C corresponding to the reproduction result of the disk 2. Becomes an error, and the address signal S41B output to the last sector detection circuit 13 becomes an error. Further, an address decode signal S41A indicating an error is output to the reference value setting circuit 36. The last sector detection circuit 13 does not detect the last sector, and no pulse is generated in the last sector signal S14A output from the one-sector delay circuit 14 at the timing C shown in FIG. As a result, the rotation angle value indicated by the rotation angle signal S31 is not taken into the capture circuit 35.

In the reference value setting circuit 36, since the spindle lock signal S40B indicates a locked state and the address decode error signal S41A indicates an error, the reference value stored in the reference value storage circuit 37 is not updated.
Thereafter, in the comparator circuit 32, the reference value previously stored in the reference value storage circuit 37 and interpolated according to the radius of the track being tracked by the reference value interpolation circuit 50, and the rotation angle value indicated by the rotation angle signal S31. Are compared with each other, and when they match, ie, as shown in FIG.
The polarity switching signal S29 is switched at the timing D shown in FIG.

As described above, the optical disk drive 2 of the present embodiment
According to FIG. 1, even when no pulse is generated in the last sector signal S14A at the timing C shown in FIG. 2, the polarity switching signal S output from the polarity switching signal generation circuit 29.
29 can be appropriately switched at timing D.
For this reason, the polarity switching signal S29 is not disturbed even when a defect such as dust adheres to the storage surface of the disk 2 and the last sector cannot be detected or a spot crosses a track. Also, since the rotation angle value indicated by the rotation angle signal S31 corresponds to the rotation of the disk 2, the scened CLV (Constant Linear
Velocity) format DVD-RAM disk 2 is used, even in the transient state where the rotation speed is changing.
The polarity switching signal S29 can be correctly changed at the switching point of the disk. Therefore, the polarity of the tracking error signal read from the disk 2 can always be matched with the polarity to be actually controlled, and a stable tracking servo can be realized.

Next, the seek operation in the optical disk drive 21 of this embodiment will be described. FIG. 3 shows a DVD-R
FIG. 4 is a diagram illustrating a tracking error signal and a polarity switching signal during a seek operation for moving a track on the AM disk 2. Here, FIG. 3A is a waveform diagram of a conventional tracking error signal without polarity control, and FIG.
FIG. 3C is a waveform diagram of the tracking error signal of the present example in which the polarity control is performed, and FIG. 3C is a waveform diagram of the polarity switching signal S29. As shown in FIG. 3A, when the polarity control is not performed, the tracking error signal is discontinuous at the disc switching timings ta, tb, and tc. Therefore, the traverse counter that counts the number of tracks crossed cannot count correctly,
An error occurs in the count result, and the accuracy of the seek operation decreases.

On the other hand, the optical disk drive 2 of the present embodiment
According to No. 1, as shown in FIG. 3 (C), the level of the polarity switching signal S29 is switched at the disk switching timings ta, tb, tc, and the polarity of the tracking error signal S8 is inverted in the polarity switching unit 9. You. As a result, the tracking error signal S9 is
As shown in (B), a continuous waveform is obtained. for that reason,
The traverse counter can obtain a correct count value, and can realize a highly accurate seek operation. Especially in this example,
An error in the polarity switching timing due to a deviation between the light spot movement straight line and the rotation center of the disk 2 is determined by a reference value interpolation circuit 5.
Since the compensation is made with 0, the polarity switching timing is properly maintained, and a high-accuracy and high-speed seek operation can be realized.

As described above, according to the optical disk drive of the present embodiment, in the tracking servo at the time of reproducing the single spiral format DVD-RAM disk 2, a highly accurate polarity switching signal S2
9 can be generated. That is, the optical disk drive 2
According to No. 1, even if there is a defect such as dust adhering to the recording surface of the disk 2 and the last sector cannot be detected, or even if the spot crosses the track, the light spot movement straight line and the disk 2 It is possible to generate a highly accurate polarity switching signal S29 that compensates for a polarity switching timing error due to a deviation from the rotation center. Further, according to the optical disk drive 21, when the DVD-RAM disk 2 having a format such as a sound CLV is used, a highly accurate polarity switching signal S29 can be generated even in a transient state in which the rotation speed is changing. As a result, according to the optical disk drive device 21, the tracking servo can be stably performed, and the seek operation can be performed at high speed and with high accuracy.

In the above example, the timing of the polarity switching signal is optimized by interpolating the rotation angle reference value according to the track radius with respect to the relative positional deviation between the moving straight line of the light spot and the rotation center of the optical disk. In the following example, a configuration for mechanically adjusting the relative positional deviation between the moving straight line of the light spot and the rotation center of the optical disc will be described. That is, in the present embodiment, the displacement between the moving straight line of the light spot by the optical pickup and the rotation center of the optical disk is mechanically adjusted by displacing the feed axis for moving the optical pickup 22.

FIGS. 5A and 5B are explanatory views showing the mechanical principle in this case. FIG. 5A shows a state before adjustment, and FIG. 5B shows a state after adjustment. Is shown. As the configuration of the control system, a configuration in which the reference value interpolation circuit 50 is omitted from the configuration shown in FIG. 1 can be used. As shown, the feed shaft (feed screw) 24 of the optical pickup 22
The end portion 24A on the inner diameter side of the optical disk 2 is rotatably supported by the support portion 26. Therefore, by displacing the end 24B on the outer diameter side of the feed shaft 24, the movement straight line of the objective lens (that is, the light spot) 22A due to the movement of the optical pickup 22 is moved to the rotation center 2 of the optical disk 2.
A can be matched.

The outer end 24B of the feed shaft 24 is slidably supported by a support (not shown), and can be fixed at any position by screws or the like. To adjust the light spot 22A
The moving straight line is made to coincide with the rotation center 2A of the optical disk 2 and then fixed. The configuration itself for displacing the feed shaft 24 of the optical pickup 22 as described above is conventionally known, for example, as disclosed in JP-A-63-71934.

Next, a method of adjusting the moving straight line of the light spot 22A to the rotation center 2A of the optical disk 2 by the displacement of the feed shaft 24 will be described. First, the moving straight line of the light spot 22A is
As a means for evaluating whether or not the rotation center 2A can be matched, for example, the rotation angle reference value of the innermost track and the rotation angle reference value of the outermost track described above are measured, and the difference is large or small. Can be used. In this case, a device for monitoring the measured rotation angle reference value from the outside is prepared, and the rotation angle reference value of the innermost track and the rotation angle reference value of the outermost track are determined while the position of the feed shaft 24 is fixed. Monitor. This work is called feed shaft 2
4 is repeated while changing the position, the feed shaft 24 is fixed at a position where the rotation angle reference value of the innermost track and the rotation angle reference value of the outermost track match, and the adjustment operation is completed.

In the case of an optical disk drive in which the light spot is divided into a main spot and a side spot, the position of the feed shaft 24 can be adjusted by checking the positional relationship between the main spot and the side spot. It is possible. That is, as shown in FIG. 5 (B), if there is no relative displacement between the moving straight line of the light spot and the rotation center of the optical disk 2, the light spot group on the recording track and the disk surface (ie, the main spot and the side spot) Is always constant regardless of the radial position of the light spot group. On the other hand, when there is a relative displacement, as shown in FIG. 5A, the relative positional relationship between the recording track and the light spot group on the disk surface changes according to the radial position of the light spot. Therefore, the above-described position adjustment of the feed shaft 24 is performed while confirming that the phase of the signal modulated by the main and side spots of these spot groups crossing the track does not change depending on the radial position of the light spot. .

In an actual optical pickup, the adjustment between the angle formed by the main spot and the side spot and the track on the optical disk is performed in a state where there is no relative displacement between the light spot movement straight line and the rotation center of the disk. For example, the phase difference between the main spot and the side spot is 18
In an optical pickup adjusted to 0 ° and without this relative position deviation, the Lissajous waveforms from the main and side spots modulated by the track are shown in FIG.
As shown in FIG. On the other hand, when there is a relative displacement, the Lissajous waveforms from the main and side spots modulated by the track are as shown in FIG. 6B. Therefore, the above-described position adjustment of the feed shaft 24 may be adjusted so as to become a linear shape shown in FIG. 6A while observing the Lissajous waveform.

As described above, the displacement between the moving straight line of the light spot by the optical pickup 22 and the rotation center of the optical disc 2 is mechanically adjusted in advance, and the moving straight line of the light spot is made to coincide with the radial direction of the optical disc 2. The rotation angle reference value updated by the reference value setting circuit 36 and stored in the reference value storage circuit 37 is constant regardless of the radius of the optical disc 2. Therefore, by using this reference value and comparing the rotation angle with the comparator circuit 32, a polarity switching signal at an appropriate timing can be generated, and an appropriate polarity switching operation of the tracking error signal can be obtained. As a result, according to the optical disk drive of the present embodiment, a single spiral format DV
In the tracking servo at the time of reproduction of the D-RAM disk 2, a highly accurate polarity switching signal S29 can be generated,
The tracking servo can be stably performed, and the seek operation can be performed at high speed and with high accuracy.

[0045]

As described above, in the optical disk drive of the present invention, the reference value in the reference value storage means, which is appropriately updated by the reference value setting means, is further interpolated by the reference value interpolation means in accordance with the track radius. The interpolated reference value is compared with the rotation angle generated by the rotation angle generation means by the comparison means, and when they match, a polarity switching signal of the tracking error signal is generated to switch the polarity of the tracking error signal. The tracking servo control of the optical disk is performed. For this reason, in the configuration in which the polarity switching signal of the tracking error signal is generated according to the rotation angle of the optical disk, the error of the polarity switching timing due to the deviation between the moving straight line of the light spot by the optical pickup and the center of the optical disk is determined by the reference value interpolation means. Since it can be removed by the interpolation processing and an appropriate polarity switching operation can be obtained, there is an effect that the tracking servo can be stably performed, and a high speed and high accuracy of the seek operation can be achieved.

Further, in the optical disk drive of the present invention, the displacement between the moving straight line of the light spot by the optical pickup and the rotation center of the optical disk is mechanically adjusted in advance by adjusting means, and the moving straight line of the optical spot is adjusted in the radial direction of the optical disk. I tried to match. Therefore, in the configuration in which the polarity switching signal of the tracking error signal is generated in accordance with the rotation angle of the optical disk, the error of the polarity switching timing due to the deviation between the moving straight line of the light spot by the optical pickup and the center of the optical disk is previously adjusted mechanically. Since it can be removed by means and an appropriate polarity switching operation can be obtained, there is an effect that the tracking servo can be stably performed, and a high speed and high accuracy of the seek operation can be achieved.

[Brief description of the drawings]

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

FIG. 2 is a timing chart showing some signal waveforms in the optical disk drive shown in FIG.

3 is a timing chart showing a waveform of a tracking error signal and a polarity switching signal waveform when the polarity control is performed and not performed in the optical disc driving device shown in FIG. 1;

4 is an explanatory diagram showing a relationship between a recording track of an optical disc and a moving straight line of a light spot in the optical disc driving device shown in FIG.

FIG. 5 is an explanatory diagram showing a principle of mechanical adjustment of a rotation center of an optical disk and a movement straight line of an optical spot in an optical disk drive according to another embodiment of the present invention.

FIG. 6 is an explanatory diagram showing a change in a Lissajous waveform based on mechanical adjustment of the rotation center of the optical disk and the movement straight line of the light spot in the optical disk drive device shown in FIG. 1;

FIG. 7 is a block diagram showing a configuration of a control system of an optical disk drive according to a prior example of the present invention.

[Explanation of symbols]

2 ... DVD-RAM disk, 3 ... Laser device, 5
…… Light receiving element, 15 …… Spindle motor, 6, 7 ……
A / D converter, 8: normal processor, 9: polarity switcher, 10: phase compensation digital filter, 11: D /
A converter, 12 drive amplifier, 13 last sector detection circuit, 14 one-sector delay circuit, 22 optical pickup, 24 feed axis, 30 PLL circuit,
31 rotation angle counter circuit, 32 comparator circuit, 35 capture circuit, 36 reference value setting circuit, 37 reference value storage circuit, 40 spindle control unit, 41 address decoding unit, 50: Reference value interpolation circuit.

Continued on the front page F term (reference) 5D117 AA02 CC01 CC04 EE07 EE14 FF11 FF14 FX02 JJ10 KK09 KK20 5D118 BA01 BC09 BC12 BF02 BF03 BF12 CA07 CA13 CD03

Claims (10)

[Claims] 1. A tracking servo for an optical disk having a recording track of a single spiral format in which lands and grooves are alternately arranged for each round is executed.
An optical disk drive for switching the polarity of a tracking error signal in accordance with a switching position between a land and a groove, comprising: a rotation angle of the optical disk based on a rotation signal corresponding to the rotation of the optical disk input from driving means for driving the rotation of the optical disk. A rotation angle generating means for generating a position, and a first position detecting a position at which a land and a groove are switched based on an address signal read from the optical disk.
Detection means, rotation angle specifying means for specifying the rotation angle generated by the rotation angle generation means at a timing corresponding to the detection of the position where the land and groove are switched, and the rotation angle generation means generated by the rotation angle generation means A reference value storage unit for storing a reference value to be compared with a rotation angle; and, when the address signal is correct, updating the reference value stored in the reference value storage unit with the rotation angle specified by the rotation angle specification unit. Reference value setting means, a second detection means for detecting the radius of the track being tracked based on the track signal read from the optical disc, and a second detection means for detecting the radius of the track detected by the second detection means. A reference value interpolation unit that interpolates a reference value stored in the reference value storage unit; and the rotation angle generated by the rotation angle generation unit. Comparing means for comparing a reference value interpolated by the reference value interpolating means and generating a polarity switching signal of the tracking error signal when the two coincide with each other; and a tracking error signal based on the polarity switching signal generated by the comparing means. And a servo control unit for performing tracking servo control of the optical disk by the optical pickup based on an output signal from the polarity switching unit. An optical disk drive, wherein a timing error of the polarity switching signal due to a deviation of a relative position of a light spot from a moving straight line by the optical pickup is compensated. 2. The interpolating means calculates a deviation amount between a moving straight line of an optical spot and a rotation center of the optical disk from a timing deviation amount between an inner track and an outer track of the optical disk, and calculates a track radius in accordance with the deviation amount. 2. The optical disk drive according to claim 1, wherein the optical disk drive is means for interpolating a reference value corresponding to the following. 3. The optical disk drive according to claim 1, further comprising a measuring unit for measuring the number of moving tracks during a seek operation by the polarity switching signal. 4. The optical disk drive according to claim 3, further comprising means for performing a seek operation using a value measured by said measuring means. 5. The optical disc according to claim 1, wherein the optical disc is an optical disc capable of recording and reproducing data.
An optical disk drive as described in the above. 6. A tracking servo for an optical disk having a recording track of a single spiral format in which lands and grooves are alternately arranged for each round is executed.
An optical disk drive for switching the polarity of a tracking error signal in accordance with a switching position between a land and a groove, comprising: a rotation angle of the optical disk based on a rotation signal corresponding to the rotation of the optical disk input from driving means for driving the rotation of the optical disk. A rotation angle generating means for generating a position, a detecting means for detecting a position at which a land and a groove are switched based on an address signal read from the optical disk, and a detecting means for detecting a position at which the land and the groove are switched. Rotation angle identification means for identifying the rotation angle generated by the rotation angle generation means at a timing; reference value storage means for storing a reference value to be compared with the rotation angle generated by the rotation angle generation means; If the signal is correct, the rotation angle specified by the rotation angle identification A reference value setting unit that updates a reference value stored in a reference value storage unit, and compares the rotation angle generated by the rotation angle generation unit with a reference value stored in the reference value storage unit. A comparison unit that generates a polarity switching signal of the tracking error signal when they match, a polarity switching unit that switches the polarity of the tracking error signal by the polarity switching signal generated by the comparison unit, and an output signal from the polarity switching unit. Servo control means for performing tracking servo control of the optical disc by the optical pickup based on the optical pickup; and adjusting means for mechanically adjusting the displacement amount between the movement straight line of the light spot by the optical pickup and the rotation center of the optical disc in advance. Optical disk drive device. 7. An optical disk drive according to claim 6, wherein said adjusting means is means for displacing a position of a feed shaft for moving said optical pickup in a substantially radial direction of said optical disk. 8. An optical disk drive according to claim 6, further comprising a measuring means for measuring the number of moving tracks during a seek operation by said polarity switching signal. 9. The optical disk drive according to claim 8, further comprising means for performing a seek operation using a value measured by said measuring means. 10. The optical disk drive according to claim 6, wherein the optical disk is an optical disk capable of recording and reproducing data.