JP2004171610A - Tracking control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tracking control device capable of promptly stabilizing the tracking control of an optical pickup for the tracks formed on an optical disk. <P>SOLUTION: The tracking control device is provided with a motor, an FG signal generator, the optical pickup, a tracking error signal generator, a comparator generating a tracking cross signal obtained by thresholding the tracking error signal and a controller turns on a tracking servo for controlling the tracking of the optical pickup to the tracks formed on the optical disk based on an FG signal formed by the FG signal generator and the tracking cross signal formed by the comparator. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a tracking control device for controlling tracking of an optical pickup with respect to a track formed on an optical disc.
[0002]
[Prior art]
A conventional tracking control device for controlling tracking of an optical pickup with respect to tracks formed on an optical disk will be described.
[0003]
FIG. 19 is a block diagram showing a configuration of a conventional tracking control device 90. The optical disk 7 is driven to rotate by a motor 6. The optical pickup 5 irradiates light to an optical disk 7 that is rotationally driven by a motor 6, and detects an electric signal based on the light reflected by the optical disk 7.
[0004]
The tracking control device 90 includes the tracking error signal generator 4. The tracking error signal generator 4 generates a tracking error signal indicating a tracking error of the optical pickup 5 with respect to a track formed on the optical disc 7 based on the electric signal detected by the optical pickup 5.
[0005]
The tracking servo controller 14 is provided in the tracking control device 90. The tracking servo controller 14 drives the optical pickup 5 based on the tracking error signal generated by the tracking error signal generator 4 so as to control the tracking of the optical pickup 5 with respect to the track formed on the optical disc 7. The tracking drive signal is output to the optical pickup 5.
[0006]
A switch 15 is provided between the tracking error signal generator 4 and the tracking servo controller 14. The tracking control device 90 has a controller 91. The controller 91 turns the switch 15 on and off.
[0007]
In the conventional tracking control device 90 configured as described above, when the motor 6 drives the optical disc 7 to rotate, the optical pickup 5 irradiates light to the optical disc 7 that is driven to rotate by the motor 6 and is reflected by the optical disc 7. An electrical signal is detected based on the light. Then, the tracking error signal generator 4 generates a tracking error signal indicating a tracking error of the optical pickup 5 with respect to the track formed on the optical disc 7 based on the electric signal detected by the optical pickup 5.
[0008]
Next, when the controller 91 turns on the switch 15, the tracking error signal generated by the tracking error signal generator 4 is input to the tracking servo controller 14. Thereafter, the tracking servo controller 14 outputs a tracking drive signal for driving the optical pickup 5 to control the tracking of the optical pickup 5 with respect to the track formed on the optical disk 7 based on the input tracking error signal. Output to 5
[0009]
Japanese Patent Application Laid-Open No. 8-96379 discloses a configuration in which tracking of the optical pickup 5 with respect to tracks formed on the optical disk 7 is stably controlled even under severe conditions in which an optical disk with a large eccentric amount rotates at high speed. . In the configuration disclosed in this publication, a relative speed between the optical disk and the optical pickup along a direction traversing a track formed on the optical disk is detected, and the detected relative speed becomes equal to or less than a preset value. When this happens, a preset pulse signal is generated, and when the optical pickup is positioned at the edge of the track, a drive signal is given to the optical pickup based on the logical product of the preset pulse signals.
[0010]
[Patent Document 1]
JP-A-8-96379
[0011]
[Problems to be solved by the invention]
However, in the configuration disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 8-96379, when the tracking servo is turned on while the optical disk 7 is rotating at a high speed, the frequency of the tracking error (TE) signal becomes high. There is a problem that the tracking pull-in process for stabilizing the tracking control of the optical pickup 5 with respect to the track formed in the above takes a longer time. Further, in the worst case, there is a problem that the tracking control cannot be stabilized.
[0012]
Further, when manufacturing an optical disk, a disk in which a hole at the center of the optical disk is shifted from the center (hereinafter referred to as “eccentricity”) can be manufactured. In such an eccentric disk, a deviation occurs between the rotation center of the optical disk itself and the rotation center of a track formed on the optical disk. Due to this shift, the relative speed between the optical disk and the optical pickup increases. As a result, the frequency of the tracking error signal further increases. Therefore, there is a problem that the tracking pull-in process for stabilizing the tracking control becomes more difficult.
[0013]
The present invention has been made to solve such a problem, and an object of the present invention is to provide a tracking control device capable of quickly stabilizing tracking control of an optical pickup for a track formed on an optical disc. .
[0014]
[Means for Solving the Problems]
In order to achieve the above object, a tracking control device according to the present invention includes: an FG signal generator that generates an FG signal indicating an angular rotation position of a motor that rotationally drives an optical disc; A tracking error signal that generates a tracking error signal indicating a tracking error of the optical pickup with respect to a track formed on the optical disc based on the electric signal detected by the optical pickup that detects the electric signal based on the reflected light; A generator for generating a tracking cross signal obtained by binarizing the tracking error signal generated by the tracking error signal generator; and a FG signal generated by the FG signal generator and a comparator generated by the comparator. The said tracking Based on the loss signal, characterized by comprising a controller for turning on the tracking servo for controlling the tracking of the optical pickup relative to the track formed on the optical disc.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
In the tracking control device according to the present embodiment, the tracking of the optical pickup with respect to the track formed on the optical disc is controlled based on the FG signal generated by the FG signal generator and the tracking cross signal generated by the comparator. Tracking servo is turned on. Therefore, the tracking servo can be turned on in a region where the frequency of the tracking error signal is low. As a result, the tracking servo can be stabilized early.
[0016]
The optical disc has a plurality of areas divided along the circumferential direction of the optical disc based on the angular rotation position of the motor indicated by the FG signal, and the controller is provided for each of the plurality of areas. Counting the tracking cross signal, selecting at least one of the plurality of regions based on a count value of the tracking cross signal counted for each of the plurality of regions, and selecting at least one of the selected plurality of regions. Preferably, the tracking servo is turned on when the optical pickup is positioned on one of the optical pickups. This is because the tracking servo is turned on in a region where the frequency of the tracking error signal is low.
[0017]
It is preferable that the controller selects an area having the smallest count value of the tracking cross signal among the plurality of areas. This is because the area where the count value of the tracking cross signal is the smallest is the area where the frequency of the tracking error signal is the lowest.
[0018]
The controller further selects an area on the opposite side of the area where the count value of the tracking cross signal is the smallest when viewed from the center of the optical disc, and sets the area on the opposite side to the area where the count value of the tracking cross signal is the smallest. Preferably, the tracking servo is turned on when the optical pickup is positioned on any of the above. This is because the number of regions where the tracking servo can be turned on is increased, so that the tracking servo can be stabilized earlier.
[0019]
It is preferable that the apparatus further includes a storage device that stores a count value of the tracking cross signal counted for each of the plurality of regions and at least one of the plurality of regions selected by the controller.
[0020]
A tracking servo controller that controls the tracking of the optical pickup based on the tracking cross signal generated by the tracking error signal generator; and a tracking servo controller provided between the tracking error signal generator and the tracking servo controller. It is preferable that the controller further includes a switch, and the controller turns on the switch based on the FG signal and the tracking cross signal. This is because the tracking servo can be turned on with a simple configuration.
[0021]
Preferably, the tracks are formed concentrically on the optical disc.
[0022]
A frequency multiplier for multiplying the FG signal generated by the FG signal generator, wherein a plurality of areas of the optical disc are rotated by the angular rotation of the motor indicated by the FG signal multiplied by the frequency multiplier; It is preferable that the image is divided based on the position. Since the optical disc is divided into more areas, the area where the tracking servo is turned on can be selected with high accuracy. Therefore, the tracking servo can be stabilized earlier.
[0023]
A direction detection signal indicating a direction of a shift along a radial direction of the optical disc between the track formed on the optical disc and the optical pickup based on the tracking error signal generated by the tracking error signal generator. Further comprising: a direction detection signal generator that generates the FG signal generated by the FG signal generator, the tracking cross signal generated by the comparator, and the direction detection signal generator. Preferably, the tracking servo is turned on based on the generated direction detection signal.
[0024]
The direction detection signal generated by the direction detection signal generator has a pulse-like waveform, the controller, each of the plurality of regions based on the rising edge of the direction detection signal and the FG signal Is preferably specified.
[0025]
It is preferable that the controller specifies each of the plurality of regions based on a rising edge and a falling edge of the direction detection signal and the FG signal.
[0026]
A direction detection signal indicating a direction of a shift along a radial direction of the optical disc between the track formed on the optical disc and the optical pickup based on the tracking error signal generated by the tracking error signal generator. Further comprising a direction detection signal generator that generates the FG signal generated by the FG signal generator, the tracking cross signal generated by the comparator, and the direction detection signal generator. It is preferable that a track jump drive signal for causing the optical head to jump by a predetermined number of tracks in the radial direction of the optical disk is provided to the optical head based on the detected direction detection signal.
[0027]
The controller, when causing the optical head to track jump from the inner circumference to the outer circumference of the optical disc, performs the track jump drive when the direction of the displacement indicated by the direction detection signal is on the outer circumference of the optical disc. Preferably, a signal is provided to the optical head.
[0028]
The controller, when causing the optical head to track-jump from the outer circumference to the inner circumference of the optical disc, performs the track jump when the direction of the displacement indicated by the direction detection signal is the inner circumference of the optical disc. Preferably, a drive signal is provided to the optical head.
[0029]
The controller, based on the tracking cross signal generated by the comparator and the direction detection signal generated by the direction detection signal generator, accelerates the light head when starting the track jump. It is preferable to change the drive value.
[0030]
The controller is configured to decelerate the light emitting head when terminating the track jump based on the tracking cross signal generated by the comparator and the direction detection signal generated by the direction detection signal generator. It is preferable to change the drive value.
[0031]
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0032]
(Embodiment 1)
FIG. 1 is a block diagram for explaining a configuration of tracking control device 100 according to Embodiment 1. The optical disk 7 is driven to rotate by a motor 6. The optical pickup 5 irradiates light to an optical disk 7 that is rotationally driven by a motor 6, and detects an electric signal based on the light reflected by the optical disk 7.
[0033]
The tracking control device 100 includes a tracking error signal generator 4. The tracking error signal generator 4 generates a tracking error signal 11 indicating a tracking error of the optical pickup 5 with respect to a track formed on the optical disk 7 based on the electric signal detected by the optical pickup 5. The tracks formed on the optical disk 7 are formed concentrically on the optical disk 7.
[0034]
The tracking control device 100 is provided with a tracking servo controller 14. The tracking servo controller 14 drives the optical pickup 5 based on the tracking error signal 11 generated by the tracking error signal generator 4 so as to control the tracking of the optical pickup 5 with respect to the track formed on the optical disk 7. Is output to the optical pickup 5.
[0035]
The tracking control device 100 includes a comparator 2. The comparator 2 generates a tracking cross signal (TKC signal) 12 by binarizing the tracking error signal 11 generated by the tracking error signal generator 4 with a threshold value that is half the amplitude of the tracking error signal 11, and generates a counter 9 Output to The counter 9 counts the tracking cross signal 12 output from the comparator 2.
[0036]
The tracking control device 100 includes an FG signal generator 3. The FG signal generator 3 generates an FG signal 10 indicating the angular rotation position of the motor 6 that rotationally drives the optical disk 7 and outputs the FG signal 10 to the edge detector 8. The edge detector 8 detects an edge of the FG signal 10 output from the FG signal generator 3.
[0037]
A switch 15 is provided between the tracking error signal generator 4 and the tracking servo controller 14. The tracking control device 90 has a controller 91. The controller 91 turns on and off the switch 15 based on the count value of the tracking cross signal 12 counted by the counter 9 and the detection result of the edge of the FG signal 10 by the edge detector 8.
[0038]
The tracking control device 100 includes a storage device 13. The storage device 13 stores information related to the count value of the tracking cross signal 12 counted by the counter 9 and timing for turning on the switch 15.
[0039]
The operation of the tracking control device 100 thus configured will be described. FIG. 2A is a diagram for describing six regions R <b> 0 to R <b> 5 divided along the circumferential direction of the optical disk 7 based on the angular rotation position of the motor 6 indicated by the FG signal 10 on the optical disk 7. FIG. 2B is a waveform diagram for explaining the operation of the tracking control device 100 according to the first embodiment.
[0040]
For the sake of simplicity, an example will be described in which the FG signal 10 indicating the angular rotation position of the motor 6 for rotating and driving the optical disk 7 is output from the FG signal generator 3 by six pulses each time the optical disk 7 rotates once. I do. The optical disk 7 has six substantially fan-shaped regions R0, R1, R2, R3, R4, and C along the circumferential direction of the optical disk 7 based on the angular rotation position of the motor 6 indicated by the FG signal 10. It is divided into a region R5.
[0041]
When the motor 6 drives the optical disk 7 to rotate, the FG signal generator 3 generates an FG signal 10 indicating the angular rotation position of the motor 6 that drives the optical disk 7 to rotate. Each one pulse of the FG signal 10 corresponds to each area of the optical disk 7. The period T0, period T1, period T2, period T3, period T4, and period T5 respectively corresponding to six consecutive pulses of the FG signal 10 correspond to the regions R0, R1, R2, R3, R4, and R4 of the optical disk 7. R5 respectively. Next, the edge detector 8 detects an edge of the FG signal 10 output from the FG signal generator 3.
[0042]
Then, the optical pickup 5 irradiates light to the optical disc 7 that is driven to rotate by the motor 6, and detects an electric signal based on the light reflected by the optical disc 7. Next, the tracking error signal generator 4 generates a tracking error signal 11 indicating a tracking error of the optical pickup 5 with respect to a track formed on the optical disk 7 based on the electric signal detected by the optical pickup 5. After that, the comparator 2 generates a tracking cross signal (TKC signal) 12 by binarizing the tracking error signal 11 generated by the tracking error signal generator 4 with a threshold of half the amplitude of the tracking error signal 11, Output to the counter 9.
[0043]
Then, based on the edge detection result of the FG signal 10 by the edge detector 8, the counter 9 generates a tracking cross signal (TKC) for each of the regions R0, R1, R2, R3, R4, and R5 on the optical disk 7. Signal) 12 and outputs it to the controller 13.
[0044]
Next, the controller 13 stores the count value of the tracking cross signal (TKC signal) 12 for each of the regions R0, R1, R2, R3, R4, and R5 output from the counter 9 in the storage device 13. I do. After that, the controller 13 selects an area in which the count value of the tracking cross signal 12 is the smallest among the areas R0, R1, R2, R3, R4, and R5, and stores the selected area in the storage device 13. Then, the controller 13 turns on the switch 15 when the optical pickup 5 is located above the area where the count value of the tracking cross signal 12 is the smallest.
[0045]
When the switch 15 is turned on by the controller 13, the tracking servo controller 14 controls the light for a track formed on the optical disc 7 based on the tracking error signal 11 input from the tracking error signal generator 4 via the switch 15. A tracking drive signal for driving the optical pickup 5 so as to control the tracking of the pickup 5 is output to the optical pickup 5.
[0046]
The region where the count value of the tracking cross signal 12 is the smallest is the region where the frequency of the tracking error signal 11 is the lowest. Therefore, when the optical pickup 5 is positioned above the region where the count value of the tracking cross signal 12 is the smallest, When the switch 15 is turned on, the tracking control of the optical pickup 5 with respect to the tracks formed on the optical disk 7 can be quickly stabilized.
[0047]
FIG. 3 is a flowchart for explaining a tracking pull-in point learning operation of the tracking control device 100 according to the first embodiment, and FIG. 4 is a flowchart for explaining an operation of turning on the tracking servo of the tracking control device 100. .
[0048]
Referring to FIG. 3, first, the controller 13 assigns an area number which is a variable for specifying any one of the six areas R0, R1, R2, R3, R4, and R5 on the optical disk 7. , The region R0 is set to zero (step S1). Then, the controller 13 determines whether or not the edge detector 8 has detected the falling edge of the FG signal 10 (Step S2). The controller 13 executes Step S2 until the edge detector 8 detects the falling edge of the FG signal 10.
[0049]
When the edge detector 8 detects the falling edge of the FG signal 10 (YES in step S2), the controller 13 adds 1 to the area number (step S3). Then, the counter 9 resets the count value of the tracking cross signal 12 to zero (Step S4). Next, the counter 9 starts counting the tracking cross signal 12 (Step S5).
[0050]
Thereafter, the controller 13 determines whether or not the edge detector 8 has again detected the falling edge of the FG signal 10 (Step S6). The controller 13 executes Step S6 until the edge detector 8 detects the falling edge of the FG signal 10 again. When the edge detector 8 determines that the falling edge of the FG signal 10 has been detected again (YES in step S6), the counter 9 stops counting the tracking cross signal 12 (step S7).
[0051]
Then, the controller 13 stores the count value of the tracking cross signal 12 counted by the counter 9 in the storage device 13 as the count value in the area indicated by the area number (step S8). Next, the controller 13 adds 1 to the area number (step S9). Thereafter, the controller 13 determines whether or not the area number is 5 or more (Step S10).
[0052]
When it is determined that the area number is not 5 or more (NO in step S10), the counter 9 resets the count value of the tracking cross signal 12 to zero (step S12). Then, the counter 9 starts counting the tracking cross signal 12 again (step S13). Next, the process returns to step S6.
[0053]
If it is determined that the area number is 5 or more (YES in step S10), the controller 13 determines the area having the smallest count value among the count values in the areas R0 to R5 stored in the storage device 13 (Step S11). Then, the process ends.
[0054]
Referring to FIG. 4, first, the controller 13 determines whether or not the edge detector 8 has detected a falling edge of the FG signal 10 (Step S21). The controller 13 executes Step S21 until the edge detector 8 detects the falling edge of the FG signal 10. When it is determined that the edge detector 8 has detected the falling edge of the FG signal 10 (YES in step S21), the controller 13 determines an area where the count value of the tracking cross signal 12 registered in the storage device 13 is the smallest. It is determined whether or not the area on the optical disk 7 where the optical pickup 5 is located is an area where the count value of the tracking cross signal 12 is the smallest (step S22). If it is determined that the area on the optical disk 7 where the optical pickup 5 is located is not the area where the count value of the tracking cross signal 12 is the smallest (NO in step S22), the process returns to step S21.
[0055]
When it is determined that the area on the optical disk 7 where the optical pickup 5 is located is the area where the count value of the tracking cross signal 12 is the smallest (YES in step S22), the controller 13 turns on the switch 15 (step S23). . After that, the process ends.
[0056]
Note that, although an example has been described in which the controller 13 turns on the switch 15 when the optical pickup 5 is positioned over an area where the count value of the tracking cross signal 12 is the smallest, the present invention is not limited to this. In FIG. 2A and FIG. 2B, for example, assuming that the region R0 has the minimum value as a result of counting the TKC, the TKC count is also small in the region R3 on the opposite side, that is, the TE signal 11 It can be seen that the frequency is low. This is due to the eccentricity of the optical disk 7, and the same result is obtained for all the optical disks. Therefore, the controller 1 further selects an area on the opposite side of the area where the count value of the tracking cross signal 12 is the smallest when viewed from the center of the optical disc 7, and selects the area opposite to the area where the count value of the tracking cross signal 12 is the smallest. The tracking servo may be turned on when the optical pickup 7 is positioned on any one of the areas. With this configuration, since the number of tracking pull-in points increases from one to two, the pull-in possible area increases, so that the pull-in time of the tracking servo is reduced to half.
[0057]
As described above, according to the first embodiment, based on the FG signal generated by the FG signal generator 3 and the tracking cross signal generated by the comparator 2, the controller 1 controls the track formed on the optical disc 7. The tracking servo for controlling the tracking of the optical pickup 5 is turned on. Therefore, the tracking servo can be turned on in a region where the frequency of the tracking error signal 11 is low. As a result, the tracking servo can be stabilized early.
[0058]
In the tracking pull-in method according to the first embodiment, it is not necessary to always measure the frequency of the tracking error signal during operation as in the configuration disclosed in Japanese Patent Application Laid-Open No. 8-96379. Therefore, the processing occupancy can be reduced.
[0059]
(Embodiment 2)
FIG. 5 is a block diagram for explaining a configuration of tracking control device 100A according to Embodiment 2. The same components as those of the tracking control device 100 according to the first embodiment described above with reference to FIG. 1 are denoted by the same reference numerals. Therefore, a detailed description of these components will be omitted. The difference from the above-described tracking control device 100 is that a multiplier 16 is further provided.
[0060]
The multiplier 16 generates an FG signal 10 </ b> A which is a double of the FG signal 10 generated by the FG signal generator 3 and outputs the signal to the edge detector 8. The edge detector 8 detects an edge of the FG signal 10 </ b> A doubled by the multiplier 16.
[0061]
The operation of the tracking control device 100A thus configured will be described. FIG. 6A is a diagram for explaining a plurality of regions R0 to R5 divided along the circumferential direction on the optical disc 7 based on the angular rotation position of the motor indicated by the FG signal 10, and FIG. b) is a diagram for explaining another plurality of regions R10 to R21 divided along the circumferential direction based on the angular rotation position of the motor indicated by the doubled FG signal 10A on the optical disc 7; FIG. 6C is a waveform diagram for explaining the operation of the tracking control device 100A.
[0062]
In the above-described first embodiment, as shown in FIG. 6A, the optical disc 7 has six substantially optical discs along the circumferential direction of the optical disc 7 based on the angular rotation position of the motor 6 indicated by the FG signal 10. It is divided into fan-shaped regions R0 to R5.
[0063]
In the second embodiment, as shown in FIG. 6B, 12 optical disks 7 are provided along the circumferential direction of the optical disk 7 based on the angular rotation position of the motor 6 indicated by the FG signal 10A multiplied by 2. Are divided into substantially fan-shaped regions R10 to R21. As described above, when the FG signal 10 is doubled by the multiplier 16, the area obtained by dividing the optical disk 7 can be increased from six to twelve.
[0064]
Referring to FIG. 6C, in the FG signal 10 before multiplication, the tracking error signal in the period T1 corresponding to the region R1 has a denser waveform than the tracking error signal in the period T2 corresponding to the region R2. . The region R2 in which the tracking error signal has a sparse waveform has a lower frequency of the tracking error signal than the region R1 in which the tracking error signal has a dense waveform. In a region where the frequency of the tracking error signal is low, the tracking pull-in becomes stable. Therefore, turning on the tracking control in the region R2 where the frequency of the tracking error signal is low can stabilize the tracking servo earlier than turning on the tracking control in the region R1 where the frequency of the tracking error signal is high.
[0065]
In the tracking error signal 11 in the period T2 corresponding to the region R2, the frequency of the tracking error signal in the latter half of the period T2 is lower than the frequency of the tracking error signal in the first half of the period T2. As described above, the frequency of the tracking error signal fluctuates even in the same region R2. For this reason, by increasing the number of divided areas on the optical disc 7, it is possible to select the area where the tracking control is turned on with higher accuracy so that the tracking servo is stabilized early.
[0066]
When the motor 6 drives the optical disk 7 to rotate, the FG signal generator 3 generates an FG signal 10 indicating the angular rotation position of the motor 6 that drives the optical disk 7 to rotate. Then, the multiplier 16 generates an FG signal 10A obtained by doubling the FG signal 10.
Each one pulse of the FG signal 10A corresponds to each of twelve areas of the optical disk 7. Periods T10 to T21 respectively corresponding to 12 consecutive pulses of the FG signal 10A correspond to twelve regions R10 to R21 of the optical disk 7, respectively. Next, the edge detector 8 detects an edge of the FG signal 10A output from the multiplier 16.
[0067]
Then, the optical pickup 5 irradiates light to the optical disc 7 that is driven to rotate by the motor 6, and detects an electric signal based on the light reflected by the optical disc 7. Next, the tracking error signal generator 4 generates a tracking error signal 11 indicating a tracking error of the optical pickup 5 with respect to a track formed on the optical disk 7 based on the electric signal detected by the optical pickup 5. After that, the comparator 2 generates a tracking cross signal (TKC signal) 12 by binarizing the tracking error signal 11 generated by the tracking error signal generator 4 with a threshold of half the amplitude of the tracking error signal 11, Output to the counter 9.
[0068]
Then, the counter 9 counts the tracking cross signal (TKC signal) 12 for each of the 12 regions R10 to R21 on the optical disk 7 based on the edge detection result of the FG signal 10 by the edge detector 8, and sends the count to the controller 13. Output.
[0069]
Next, the controller 13 stores the count value of the tracking cross signal (TKC signal) 12 for each of the 12 regions R10 to R21 output from the counter 9 in the storage device 13. Thereafter, the controller 13 selects an area in which the count value of the tracking cross signal 12 is the smallest from the 12 areas R10 to R21, and stores the selected area in the storage device 13. Then, the controller 13 turns on the switch 15 when the optical pickup 5 is located above the area where the count value of the tracking cross signal 12 is the smallest.
[0070]
As described above, according to the second embodiment, the optical disc 7 further includes the multiplier 16 for multiplying the FG signal generated by the FG signal generator 3. It is divided based on the angular rotation position of the motor 6 indicated by the FG signal 10A multiplied by 16. For this reason, since the optical disk is divided into more areas, the area where the tracking servo is turned on can be selected with high accuracy. As a result, the tracking servo can be stabilized earlier.
[0071]
(Embodiment 3)
FIG. 7 is a block diagram for explaining a configuration of tracking control device 100B according to Embodiment 3. The same components as those of the tracking control device 100 according to the first embodiment described above with reference to FIG. 1 are denoted by the same reference numerals. Therefore, a detailed description of these components will be omitted. The difference from the above-described tracking control device 100 is that a direction detection signal generator 17 and a synchronization detector 21 are further provided, and a controller 1A is provided instead of the controller 1.
[0072]
Based on the tracking error signal 11 generated by the tracking error signal generator 4, the direction detection signal generator 17 shifts the track formed on the optical disk 7 and the optical pickup 5 along the radial direction of the optical disk 7. , And outputs it to the controller 1A and the synchronization detector 21.
[0073]
The synchronization detector 21 generates the direction detection signal 18 and the FG signal 10 based on the direction detection signal 18 output from the direction detection signal generator 17 and the edge detection result of the FG signal 10 output from the edge detector 8. Detect synchronization.
[0074]
FIG. 8A is a diagram for explaining the eccentricity of the optical disk 7 in the tracking control device 100B according to the third embodiment, and FIG. 8B is a diagram for explaining the operation principle of the tracking control device 100B. It is a waveform diagram.
[0075]
Referring to FIG. 8A, each concentric circle drawn by a dotted line indicates a recording track recorded concentrically with the innermost circumference as a hole. Of the two concentric circles drawn by solid lines, the inner circle shows a hole when the optical disc 7 is eccentric, and the outer circle shows a hole when an eccentric disc having a hole drawn by a solid line is reproduced. Shows the trajectory followed by the fixed optical pickup. Similarly to the first embodiment, the optical disk 7 has six substantially fan-shaped regions R0, R1, and R2 along the circumferential direction of the optical disk 7 based on the angular rotation position of the motor 6 indicated by the FG signal 10. It is divided into R2, region R3, region R4 and region R5.
[0076]
Here, attention is paid to the region R0. When the optical pickup 5 is fixed when the eccentric disk 7 rotates, the circle indicating the locus followed by the optical pickup 7 and the position of the recording track show that the optical pickup 7 at the beginning of the region R0. The position of the optical pickup 7 at the end of the region R0 is shifted toward the outside of the optical disk 7 by a half track with respect to the position of.
[0077]
This deviation appears as the density of the waveform of the tracking error signal 11. Paying attention to the region R1, there is a shift of one track between the start position and the end position. Looking at the waveform of the tracking error signal 11, the tracking error signal 11 in the period T1 corresponding to the region R1 is denser than the tracking error signal 11 in the period T0 corresponding to the region R0.
[0078]
Referring to FIG. 8A, each arrow shown in the regions R0 to R5 of the optical disk indicates a shift amount and a shift direction between the position of the optical pickup 5 and the position of the recording track. The direction detection signal 18 has a pulse shape. When in the high state, the direction of deviation of the optical pickup 5 from the track is toward the outside of the optical disk 7, and when in the low state, the optical pickup 5 is in the optical pickup state. 5 indicates that the direction of deviation from the track is toward the inside of the optical disk 7. The shift amount of the optical pickup 5 with respect to the track can be obtained by counting the tracking cross signal 12.
[0079]
As described above, the direction of deviation of the optical pickup 5 from the track can be obtained based on the direction detection signal 18, and the amount of deviation of the optical pickup 5 from the track can be obtained based on the tracking cross signal 12.
[0080]
FIG. 9 is a waveform diagram for explaining the operation of tracking control device 100B according to Embodiment 3. The FG signal 10 is one cycle of the disk in six cycles. When giving six area numbers R0 to R5 to each of the six periods of the FG signal 10, in the above-described first and second embodiments, it is necessary to consider the actual position of the optical disk 7. Did not. This is because the FG signal 10 was continuously output from the FG signal generator 3 after the rotation of the optical disk 7 reached a certain speed.
[0081]
However, if the FG signal 10 is interrupted as a result of the stoppage of the rotation of the optical disk 7, for example, the area number and the actual position of the optical disk 7 deviate, so that it is necessary to obtain disk information indicating the actual position of the optical disk again. is there.
[0082]
Therefore, the direction detection signal 18 is used to match the area number with the actual position of the optical disk 7. The feature of the direction detection signal 18 is that the direction detection signal 18 is a pulse signal whose edge changes at the folded portion 31 of the tracking error signal 11. In other words, the cycle of the direction detection signal 18 coincides with the time during which the optical pickup 5 makes one round around the optical disk. When the area numbers are sequentially assigned from R0 in accordance with the rising edge 19 of the direction detection signal 18, the area numbers and the actual position of the optical disk 7 can be matched.
[0083]
When the optical disc 7 is started up for the first time, with the focus servo on, the synchronization detector 21 synchronizes the rising edge 19 of the direction detection signal 18 with the falling edge of the FG signal 10 to obtain the area number and The count value of the tracking cross signal (TKC) is stored in the storage device 13 in association with the count value.
[0084]
Then, the controller 1 </ b> A searches for an area in which the count value of the tracking cross signal (TKC) is the smallest among the areas R <b> 0 to R <b> 5 and stores the area in the storage device 13. Next, the controller 1A turns on the switch 15 in order to start tracking servo control in an area where the count value of the tracking cross signal (TKC) is minimum.
[0085]
When the optical disk 7 is started for the second time or later, information obtained when the optical disk 7 is started for the first time is used. When the focus servo is on, a rising edge 19 of the direction detection signal 18 is detected, and an area number assigned in synchronization with the rising edge 19 of the direction detection signal 18 at the time of the first learning is used.
[0086]
As described above, once the information of the optical disk 7 is obtained, even if the optical disk 7 stops and the FG signal 10 is interrupted, the direction detection signal 18 is output from the direction detection signal generator 17 unless the optical disk 7 is replaced. At this point, the information of the optical disk 7 obtained previously can be reused. Since a simple configuration for detecting the rising edge 19 of the direction detection signal 18 at the time of re-learning is used, the processing performance is improved, and the restart time can be reduced.
[0087]
FIG. 10 is a waveform chart for explaining another operation of the tracking control device 100B according to the third embodiment. The same components as those in the waveform diagram for describing the operation of the tracking control device 100B described above with reference to FIG. 9 are denoted by the same reference numerals. Therefore, a detailed description of these components will be omitted.
[0088]
When the optical disc 7 is started up for the first time and the focus servo is on, the synchronization detector 21 synchronizes the rising edge 19 of the direction detection signal 18 with the falling edge of the FG signal 10 to obtain the area number and TKC The count value is stored in the storage device 13 in association with the count value.
[0089]
Then, the synchronization detector 21 synchronizes the falling edge 20 of the direction detection signal 18 with the falling edge of the FG signal 10 and stores the area number and the TKC count value at that time in the storage device 13 in association with each other.
[0090]
Next, the controller 1 </ b> A searches for an area having the smallest TKC count value among the areas R <b> 0 to R <b> 5, and stores it in the storage device 13. Next, the controller 1A turns on the switch 15 to start the tracking servo control in a region where the TKC count value is the minimum.
[0091]
When the optical disk 7 is started up for the second time or later, information obtained when the optical disk 7 is started up for the first time is used. Either the rising edge 19 or the falling edge 20 of the direction detection signal 18 is detected in a state where the focus servo is on, and is given in synchronization with the rising edge 19 or the falling edge 20 of the direction detection signal 18 at the time of the first learning. Use the specified area number.
[0092]
By providing two reference positions in this way, relearning can be executed in half the time as compared with the operation described above with reference to FIG.
[0093]
According to the third embodiment, if learning is performed once at the time of disk startup by performing synchronization detection with the direction detection signal, it is not necessary to perform re-learning at the second and subsequent disk startups. Therefore, as long as the recording medium disk is not replaced, the time for starting the disk can be reduced.
[0094]
(Embodiment 4)
FIG. 11 is a diagram for explaining the principle of track jump processing in the tracking control device according to the fourth embodiment. In the track jump process, the pulse drive 32 of the track jump drive signal 23 is forcibly applied at time 21 in a state where the tracking servo is turned off, and the optical head 5 is moved by a predetermined number of tracks along the radial direction of the optical disk 7. , A pulse drive 33 having a polarity opposite to that of the pulse drive 32 is applied at a time 22, and then the tracking servo is turned on again.
[0095]
FIG. 12A is a diagram for explaining the eccentricity of the optical disc in the tracking control device according to the fourth embodiment, and FIG. 12B is a diagram for explaining the operation of the tracking control device according to the fourth embodiment. It is a waveform diagram.
[0096]
An example in which the optical head 5 causes a track jump from the inner circumference to the outer circumference of the optical disk 7 having an eccentric component will be described. If the force of the eccentric component toward the inner circumferential direction is larger than the force of the acceleration drive for causing the optical head 5 to track jump from the inner circumferential side to the outer circumferential direction of the optical disk 7, the light is directed toward the outer circumferential direction. Although the head 5 is accelerated, the optical head 5 may move in the inner circumferential direction due to the force of the eccentric component in the inner circumferential direction that is larger than the acceleration driving force in the outer circumferential direction. is there.
[0097]
Therefore, when the optical head 5 is caused to make a track jump toward the outer periphery, the optical head 5 is caused to make a track jump when the optical head 5 is located on a region where the eccentric component acts toward the outer periphery. Thus, the track jump of the optical head 5 can be accurately performed.
[0098]
In the example shown in FIGS. 12A and 12B, any one of the period T0, the period T1, and the period T2 corresponding to the region R0, the region R1, and the region R2 in which the eccentric component works in the outer peripheral direction. In the above, the pulse drive 32 of the track jump drive signal 23 for causing the optical head 5 to make a track jump may be given to the optical head 5.
[0099]
Similarly, when the optical head 5 is caused to perform a track jump from the outer peripheral side to the inner peripheral side of the optical disc 7, when the optical head 5 is located above the region where the eccentric component works in the inner peripheral direction. By causing the optical head 5 to make a track jump, the optical head 5 can make a track jump accurately.
[0100]
In the example shown in FIGS. 12A and 12B, any one of the period T3, the period T4, and the period T5 respectively corresponding to the region R3, the region R4, and the region R5 in which the eccentric component works in the inner circumferential direction. In this case, a pulse drive 32 of a track jump drive signal 23 for causing the optical head 5 to perform a track jump may be given to the optical head 5.
[0101]
(Embodiment 5)
FIG. 13 is a diagram for explaining the principle of the operation of starting the track jump in the tracking control device according to the fifth embodiment, and FIG. 14 is a diagram for explaining the operation of starting the track jump. FIG. 8 is a diagram for explaining another operation for starting a track jump.
[0102]
Consider a case where the optical pickup 5 causes a track jump from the inner circumference to the outer circumference of the optical disc 7. FIG. 13 illustrates the acceleration drive time when the eccentric component of the optical disk 7 is zero. FIG. 14 is a diagram for explaining the acceleration drive time when the eccentric component of the optical disk 7 acts in the inner circumferential direction and an external force acts on the optical pickup 5 in the outer circumferential direction. Things. FIG. 15 is a diagram for explaining the acceleration driving time when the eccentric component is acting toward the outer periphery and an external force is acting on the optical pickup 5 toward the inner periphery. .
[0103]
As shown in FIG. 13, when the eccentric component is zero, the optical pickup 5 can be caused to perform normal track jump by giving the acceleration drive pulse 32 for a predetermined acceleration drive time T1.
[0104]
However, as shown in FIG. 14, when the eccentric component acts in the inner circumferential direction, a force is applied in the same direction as the acceleration direction. Therefore, when the eccentric component is zero, the acceleration driving pulse 32 is applied. It is necessary to apply the acceleration drive pulse 32A only during the acceleration drive time T12 shorter than the drive time T11.
[0105]
When the eccentric component acts toward the outer peripheral direction as shown in FIG. 15, a force is applied in a direction opposite to the acceleration direction. It is necessary to apply the acceleration drive pulse 32B for the acceleration drive time 13 longer than the time T11.
[0106]
Considering these, the acceleration drive time is
Acceleration drive time = Standard acceleration time + Direction detection signal × TKC count value in FG area × α (coefficient) (Equation 1)
Can be determined by:
[0107]
Here, the direction detection signal is -1 when the eccentric component is acting toward the outer peripheral direction, and is +1 when the eccentric component is acting toward the inner peripheral direction.
[0108]
The coefficient α is determined after confirming the actual device.
[0109]
FIG. 16 is a diagram for explaining the principle of the operation for ending the track jump in the tracking control device according to the fifth embodiment, and FIG. 17 is a diagram for explaining the operation for ending the track jump. FIG. 9 is a diagram for explaining another operation for ending the track jump.
[0110]
Similar to FIGS. 13 to 15 described above, a case where the optical pickup 5 causes a track jump from the inner circumference to the outer circumference of the optical disk 7 will be considered. FIG. 16 is for explaining the deceleration drive time when the eccentric component is zero. FIG. 17 illustrates the deceleration driving time when the eccentric component acts toward the inner circumference of the optical disc 7 and an external force acts on the optical pickup 5 toward the outer circumference. It is. FIG. 18 is a diagram for explaining the deceleration driving time when the eccentric component acts in the outer circumferential direction and an external force acts on the optical pickup 5 in the inner circumferential direction.
[0111]
As shown in FIG. 16, when the eccentricity component is zero, the optical pickup 5 can be caused to perform normal track jump by giving the deceleration drive pulse 33 for a predetermined deceleration drive time T14.
[0112]
However, when the eccentric component acts on the optical pickup 5 in the inner circumferential direction as shown in FIG. 17, a force is applied in the same direction as the acceleration direction. It is necessary to apply the deceleration drive pulse 33A only during the deceleration drive time T15 longer than the deceleration drive time T14 that gives.
[0113]
When the eccentric component acts on the optical pickup 5 toward the outer peripheral direction as shown in FIG. 18, a force is applied in a direction opposite to the acceleration direction. It is necessary to give the deceleration drive pulse 33B only for the deceleration drive time 16 shorter than the deceleration drive time T14 that gives
[0114]
Considering these, the deceleration drive time is
Deceleration drive time = standard deceleration time + direction detection signal × TKC count value in FG area × β (coefficient) (Equation 2)
Can be determined by:
[0115]
Here, the direction detection signal is -1 when the eccentric component is acting toward the outer periphery, and is +1 when the eccentric component is acting toward the inner periphery.
[0116]
The coefficient β is determined after confirming the actual machine.
[0117]
As described above, also in the track jump, the jump start timing and the acceleration / deceleration drive value can be changed according to the eccentric component based on the direction detection signal. For this reason, the optical pickup 5 can accurately make a track jump.
[0118]
【The invention's effect】
As described above, according to the present invention, it is possible to provide a tracking control device capable of quickly stabilizing the tracking control of the optical pickup with respect to tracks formed on an optical disc.
[Brief description of the drawings]
FIG. 1 is a block diagram for explaining a configuration of a tracking control device according to a first embodiment.
FIG. 2A is a diagram illustrating a plurality of regions divided along a circumferential direction based on an angular rotation position of a motor indicated by an FG signal on an optical disc of the tracking control device according to the first embodiment; FIG.
(B) is a waveform diagram for explaining the operation of the tracking control device according to the first embodiment.
FIG. 3 is a flowchart for explaining a tracking pull-in point learning operation of the tracking control device according to the first embodiment.
FIG. 4 is a flowchart for explaining an operation of turning on a tracking servo of the tracking control device according to the first embodiment;
FIG. 5 is a block diagram for explaining a configuration of a tracking control device according to a second embodiment.
FIG. 6A is a diagram illustrating a plurality of areas divided along a circumferential direction based on an angular rotation position of a motor indicated by an FG signal on an optical disc of a tracking control device according to a second embodiment; FIG.
(B) is a diagram for explaining another plurality of areas divided along the circumferential direction based on the angular rotation position of the motor indicated by the FG signal on the optical disc of the tracking control device according to the second embodiment. And
(C) is a waveform diagram for explaining an operation of the tracking control device according to the second embodiment.
FIG. 7 is a block diagram illustrating a configuration of a tracking control device according to a third embodiment.
FIG. 8A is a diagram for explaining eccentricity of an optical disc in a tracking control device according to a third embodiment;
(B) is a waveform diagram for explaining the operation principle of the tracking control device according to the third embodiment.
FIG. 9 is a waveform chart for explaining an operation of the tracking control device according to the third embodiment.
FIG. 10 is a waveform chart for explaining another operation of the tracking control device according to the third embodiment.
FIG. 11 is a diagram for explaining the principle of a track jump operation of the tracking control device according to the fourth embodiment.
FIG. 12A is a diagram for explaining eccentricity of an optical disc in a tracking control device according to a fourth embodiment;
(B) is a waveform diagram for explaining an operation of the tracking control device according to the fourth embodiment.
FIG. 13 is a diagram for explaining a principle of an operation of starting a track jump in the tracking control device according to the fifth embodiment.
FIG. 14 is a diagram for explaining an operation of starting a track jump in the tracking control device according to the fifth embodiment.
FIG. 15 is a diagram for explaining another operation of starting a track jump in the tracking control device according to the fifth embodiment.
FIG. 16 is a diagram for explaining a principle of an operation of ending a track jump in the tracking control device according to the fifth embodiment.
FIG. 17 is a diagram illustrating an operation of ending a track jump in the tracking control device according to the fifth embodiment.
FIG. 18 is a diagram for explaining another operation of ending the track jump in the tracking control device according to the fifth embodiment.
FIG. 19 is a block diagram showing a configuration of a conventional tracking control device.
[Explanation of symbols]
1 Controller
2 Comparator
3 FG signal generator
4 Tracking error signal generator
5 Optical pickup
6 motor
7 Optical disk
8 Edge detector
9 Counter
10 FG signal
11 Tracking error signal
12 Tracking cross signal
13 Storage device
14 Tracking servo controller
15 switches
16 multiplier
17 Direction detection signal generator
18 Direction detection signal
19 rising edge
20 Falling edge
21 Sync detector
23, 24, 25 track jump drive signal
32, 33 drive pulse
T11, T12, T13 Acceleration drive period
T14, T15, T16 Deceleration drive period

Claims (16)

An FG signal generator that generates an FG signal indicating an angular rotation position of a motor that rotationally drives the optical disc;
A tracking error of the optical pickup with respect to a track formed on the optical disc based on the electric signal detected by the optical pickup that irradiates the optical disc with light and detects an electric signal based on the light reflected by the optical disc. A tracking error signal generator that generates a tracking error signal indicating
A comparator that generates a tracking cross signal obtained by binarizing the tracking error signal generated by the tracking error signal generator;
A tracking servo for controlling tracking of the optical pickup with respect to the track formed on the optical disc based on the FG signal generated by the FG signal generator and the tracking cross signal generated by the comparator; A tracking control device, comprising: a controller that turns on the tracking control device. The optical disc has a plurality of areas divided along a circumferential direction of the optical disc based on the angular rotation position of the motor indicated by the FG signal,
The controller counts the tracking cross signal for each of the plurality of regions, and selects at least one of the plurality of regions based on a count value of the tracking cross signal counted for each of the plurality of regions, The tracking control device according to claim 1, wherein the tracking servo is turned on when the optical pickup is positioned on at least one of the selected plurality of regions. The tracking control device according to claim 2, wherein the controller selects an area having the smallest count value of the tracking cross signal among the plurality of areas. The controller further selects an area on the opposite side of the area where the count value of the tracking cross signal is the smallest when viewed from the center of the optical disc,
4. The tracking control device according to claim 3, wherein the tracking servo is turned on when the optical pickup is positioned on one of a region where the count value of the tracking cross signal is the smallest and a region on the opposite side. 5. The tracking control according to claim 2, further comprising a storage device that stores a count value of the tracking cross signal counted for each of the plurality of regions and at least one of the plurality of regions selected by the controller. apparatus. A tracking servo controller that controls the tracking of the optical pickup based on the tracking cross signal generated by the tracking error signal generator;
It further comprises a switch provided between the tracking error signal generator and the tracking servo controller,
The tracking control device according to claim 1, wherein the controller turns on the switch based on the FG signal and the tracking cross signal. The tracking control device according to claim 1, wherein the track is formed concentrically on the optical disc. A frequency multiplier for multiplying the FG signal generated by the FG signal generator;
3. The tracking control device according to claim 2, wherein the plurality of areas of the optical disc are divided based on the angular rotation position of the motor indicated by an FG signal multiplied by the multiplier. A direction detection signal indicating a direction of a shift along a radial direction of the optical disc between the track formed on the optical disc and the optical pickup based on the tracking error signal generated by the tracking error signal generator. Further comprising a direction detection signal generator that generates
The controller controls the tracking servo based on the FG signal generated by the FG signal generator, the tracking cross signal generated by the comparator, and the direction detection signal generated by the direction detection signal generator. The tracking control device according to claim 1, which is turned on. The direction detection signal generated by the direction detection signal generator has a pulse-like waveform,
The tracking control device according to claim 2, wherein the controller specifies each of the plurality of regions based on a rising edge of the direction detection signal and the FG signal. The tracking control device according to claim 10, wherein the controller specifies each of the plurality of regions based on a rising edge and a falling edge of the direction detection signal and the FG signal. A direction detection signal indicating a direction of a shift along a radial direction of the optical disc between the track formed on the optical disc and the optical pickup based on the tracking error signal generated by the tracking error signal generator. And a direction detection signal generator that generates
The controller calculates a radius of the optical disc based on the FG signal generated by the FG signal generator, the tracking cross signal generated by the comparator, and a direction detection signal generated by the direction detection signal generator. 10. The tracking control device according to claim 9, wherein a track jump drive signal for causing the optical head to perform a track jump by a predetermined number of tracks along the direction is provided to the optical head. The controller, when causing the optical head to track jump from the inner circumference to the outer circumference of the optical disc, performs the track jump drive when the direction of the displacement indicated by the direction detection signal is on the outer circumference of the optical disc. 13. The tracking control device according to claim 12, wherein a signal is provided to the optical head. The controller, when causing the optical head to make a track jump from the outer peripheral side to the inner peripheral side of the optical disc, performs the track jump when the direction of the displacement indicated by the direction detection signal is the inner peripheral side of the optical disc. 13. The tracking control device according to claim 12, wherein a drive signal is provided to the optical head. The controller, based on the tracking cross signal generated by the comparator and the direction detection signal generated by the direction detection signal generator, accelerates the light head when starting the track jump. 13. The tracking control device according to claim 12, wherein the driving value is changed. A controller for decelerating the light head when terminating the track jump based on the tracking cross signal generated by the comparator and the direction detection signal generated by the direction detection signal generator. 13. The tracking control device according to claim 12, wherein the driving value is changed.

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