JPH1139776A - Optical disk driving device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten a search time by performing a fine searching operation without closing a tracking control loop even after a coarse searching operation is completed and making the number of track traversing lines of the fine searching operation a value in which the number of lines counted in the coarse searching operation is subtracted from a specified number of lines to dispense with a pull-in time and an address reading time. SOLUTION: A controller 17 calculates a distance by comparing the address at the point of time of starting a rough search with the address of a search target point to specify it to a coarse search means 15. The coarse search means 15 moves an optical pickup to the track direction by driving a traverse mechanism 13. At the same time, the controller 17 outputs the number of target track traversing lines of a total searching operation to a subtracting means 32. Then, the controller counts the number of actrually traversed track lines while performing the coarse searching operation and absorbs the number of error lines of the coarse seaching operation by performing a fine search by the number of error lines between the number of coarse searching lines and the number of the target track traversing lines instantly at the time of completing the coarse search.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to search control in an optical disk drive.

[0002]

2. Description of the Related Art In a recent optical disk drive,
It is widely used as a computer peripheral device, and demand for cost reduction is remarkable. In such a situation, a technique for speeding up a search using a simple mechanism with low cost is important.

Hereinafter, search control in a conventional optical disk drive will be described. FIG. 7 is a block diagram of a conventional optical disk drive. 1 is an optical disk, 2 is a rotating means for rotating the optical disk 1, and 3 is an optical disk 1.
A condensing lens for converging a light beam on the recording surface of the optical disc 1 to form a light spot; 4 a tracking actuator for moving the light spot by moving the condensing lens 3 in a direction perpendicular to the track of the optical disc 1; Optical disk 1
A light receiving element for receiving reflected light from the optical disc and detecting a relative position error between the light spot and the track (ie, a tracking error signal) and an information signal recorded on the disk recording surface;
Reference numeral 6 denotes a tracking control means for forming a tracking control loop by performing a filter operation such as phase compensation with a tracking error signal output from the light receiving element 5 as an input. Track number counting means for counting the number of track crossings by counting the number of zero crossings (or falling), and a cycle detecting means 8 for detecting a zero cross cycle of the rising (or falling) of the tracking error signal output from the light receiving element 5. , 9 drive the tracking actuator 4 until the number of track crossings counted by the track number counting means 7 reaches a value designated by the controller 17 while controlling the cycle so that the cycle detected by the cycle detecting means 8 becomes a predetermined cycle. Fine search means for performing a fine search operation 0 selecting means for selecting the output and the ground level of the output and fine search means 9 of the tracking control means 6 in response to a control signal output 21 of the controller 17,
11 is a tracking driving means for driving the tracking actuator 4 by using the output of the selecting means 10 as an input;
Is a traverse mechanism for transporting the optical pickup including the condenser lens 3, the tracking actuator 4, and the light receiving element 5 in the radial direction of the disk, 14 is a stepping motor for driving the traverse mechanism 13, and 15 is
A coarse search means for performing a coarse search operation for moving the optical pickup by a predetermined distance by step-feeding the stepping motor according to a value designated by the controller;
6 is an address detecting means for reading an address signal recorded on the optical disc 1 from the output of the light receiving element 5, 17 is a controller for controlling the fine search means 9, selecting means 10 and coarse search means 15, and 18 is an address signal input of the controller 17 , 19 are the step feed number outputs of the controller 17,
Reference numeral 20 denotes a designated number output of the number of track crossings to the fine search means 9 of the controller 17, and reference numeral 21 denotes a control signal output to the selection means 10.

The operation of the conventional optical disk drive configured as described above will be described below with reference to FIG. FIG. 8 is a waveform diagram schematically showing the operation of the conventional optical disc drive during search control.

[0005] In FIG. 8, A is a tracking error signal waveform output from the light receiving element 5, and B is tracking control means 6.
, C represents the rotation speed of the stepping motor 14, D represents the cumulative value of the number of track crossings counted by the track number counting means 7 during the search operation, and Nref represents the sum of the coarse search and the fine search. Nrough indicates the number of traverses during the coarse search operation, and Nfine indicates the number of traverses during the fine search operation. T
0 is a period during which the tracking control loop is closed before the start of the search operation, T1 is a coarse search operation period, T2 is a tracking control pull-in period immediately after the coarse search operation, T3 is an address reading time, and T4 is a fine search period.

In a state before the start of the search operation, the selection means 10 selects the output of the tracking control means 6 by the control signal output 21 of the controller 17 to close the tracking control loop, and the light spot follows the track ( Period T0 in FIG. 8).

At the time of the search operation, first, the selection means 10 selects the ground level by the control signal output 21 of the controller 17, and the tracking control loop is opened. Since the rotation angle of the stepping motor 14 can be changed by a desired number of steps in accordance with the drive waveform, any positioning can be basically performed by open control (however, an error corresponding to the step resolution occurs). Therefore, the controller 17 reads the address at the start of the coarse search from the address detecting means 16, compares the read address with the address of the search target point, calculates the distance traveled in the coarse search, and converts this to the number of feed steps of the stepping motor 14. Is specified to the coarse search means 15 as the step feed number output 19.

The coarse search means 15 performs step feed of the stepping motor 14 according to the designated number of steps, and moves the optical pickup in the track direction by the traverse mechanism 13 (period T1 in FIG. 8).

At this time, the rotation speed of the stepping motor 14 is formed into a triangular waveform as shown by C in a period T1 in FIG. 8, thereby preventing stepping out of the stepping motor at the time of starting and stopping, and reducing the moving time. Can be shortened. This completes the coarse search, but the resolution of the step feed is usually several tens of the pitch of one track, and is concentric (or spiral) with the center of rotation of the disk.
Since the center of the circular track has an error (so-called eccentricity), the target number of coarse searches does not usually match the actually moved number. Therefore, a precise search for driving the tracking actuator is required next.

After the coarse search is completed in order to obtain the target number of the fine search, the selection means 10 again selects the output of the tracking control means 6 by the control signal 21 of the controller 17, and the tracking control loop is closed. When the tracking control pulls in and the light spot follows the track, the controller 17 reads the address again by the address detection means 16, calculates the number of fine search from the difference from the target address, and outputs the specified number output 20 to the fine search means 9. The selection means 10 selects the output of the fine search means 9 by the control signal output 21 and starts the fine search operation. The fine search means compares the output of the cycle detection means 8 with a predetermined value, controls the tracking actuator so that the relative movement cycle between the light spot and the track becomes a predetermined value, and uses the output of the tracking number counting means 7 to determine the number of track crossings. When the number reaches the designated number, the controller 17
The selection means 10 selects the output of the tracking control means 6 according to the control signal output 21 of the above, the tracking control loop is closed, and the fine search is completed, thereby completing a series of search operations.

[0011]

However, the above conventional configuration has a problem that the time required from the end of the coarse search operation to the start of the fine search operation is long, and the search operation time is increased. I was This will be described with reference to FIG.

After the coarse search period T1 ends, it is necessary to close the tracking control loop so that the light spot follows the track in order to read the address, and a tracking control pull-in time T2 is required. Here, during the coarse search, the tracking actuator vibrates due to the acceleration of moving the optical pickup, so that the relative speed between the light spot and the track is large immediately after the coarse search, and it is difficult to perform the tracking control pull-in operation.

Normally, the gain crossing point of the loop transfer characteristic of the tracking control loop of a compact disk (hereinafter abbreviated as CD) or a mini-disc (hereinafter abbreviated as MD) is 1 to 2 in consideration of playability with respect to disk surface flaws. It is necessary to be 1.5 kHz or less, and in such a servo band, the relative speed between the light spot and the track is 3 kHz.
Unless it is less than about z, it is difficult to stably pull in.

However, the relative speed due to the vibration of the tracking actuator due to the acceleration during the coarse search is usually 3 kHz.
Since z is larger than z, it is necessary to take measures such as waiting for the vibration of the tracking actuator to settle in order to stably pull in the tracking control. As the coarse search speed increases, the vibration also increases, so the waiting time needs to be increased, and the operation also becomes unstable. As a result, the pull-in time T2 increases, which hinders a reduction in the search time. Further, an address reading time T3 is required after the tracking control is performed. For example, in a CD or MD rotating at a normal speed, an address is written about every 13.3 msec.
c reading time is required.

The present invention solves the above-mentioned conventional problems, and provides an optical disk drive capable of shortening the search time by eliminating the pull-in time and the address reading time of the tracking control after the end of the coarse search operation. The purpose is to do.

[0016]

In order to achieve this object, an optical disk drive according to the present invention comprises: a coarse search means for performing a coarse search operation for moving an optical pickup in a disk radial direction; Moving state detecting means for detecting a moving direction and a moving speed, and fine searching means for performing a fine searching operation for driving a tracking actuator in accordance with an output of the moving state detecting means to cause a light spot to cross a track at a predetermined cycle. And counting means for counting the number of tracks that the light spot traverses the track, and search control means for controlling the coarse search means and the fine search means to change the track followed by the light spot according to the designated number. The search control means performs a fine search operation without closing the tracking control loop after the coarse search operation is completed. Performed, the track crossing number of fine search operation is to a value obtained by subtracting the counted number of tracks by the counting means from the specified number during coarse search operation. With this configuration, the error in the number of track crossings caused by the coarse search operation can be immediately absorbed by the fine search operation without closing the tracking control loop, so that the tracking control between the coarse search operation and the fine search operation is pulled in. Time and address reading time can be made unnecessary.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention provides a means for forming a light spot by converging a light beam on an information surface of an optical disk on which an information signal is recorded in a predetermined track form. An optical pickup comprising: a tracking actuator that moves the light spot in the disk radial direction; and a unit that detects a relative position error of the light spot and the track in the disk radial direction by detecting reflected light from the information surface; Driving the tracking actuator according to the relative position error to form a tracking control loop to cause the light spot to follow the track; and a coarse search operation for moving the optical pickup in a disk radial direction. Coarse search means for performing, relative movement of the light spot and the track Moving state detecting means for detecting a degree, and fine searching means for performing a fine searching operation for causing the light spot to traverse the track at a predetermined cycle by driving the tracking actuator according to the output of the moving state detecting means; A search unit that counts the number of tracks that the light spot traverses the track; and a search control that controls the coarse search unit and the fine search unit to change the track that the light spot follows according to the designated number. Means for performing the fine search operation without closing the tracking control loop after completion of the coarse search operation, and the number of track traversals of the fine search operation is calculated from the specified number of tracks by the coarse search operation. In this case, the number of tracks counted by the counting means is subtracted.

According to a second aspect of the present invention, there is provided means for forming a light spot by condensing a light beam on an information surface of an optical disk on which an information signal is recorded in a predetermined track form, and forming the light spot on the information surface. An optical pickup comprising: a tracking actuator for moving in a disk radial direction; and means for detecting a relative position error in the disk radial direction between the light spot and the track by detecting reflected light from the information surface; and the relative position error. A tracking control means for forming a tracking control loop by driving the tracking actuator in accordance with the following so that the light spot follows the track, and a coarse search means for performing a coarse search operation for moving the optical pickup in a disk radial direction. And the relative speed of movement of the light spot and the track. Moving state detecting means, a decelerating means for performing a decelerating operation for lowering a relative moving speed of the light spot and the track by driving a tracking actuator in accordance with an output of the moving state detecting means, and driving the tracking actuator A fine search means for performing a fine search operation of causing the light spot to traverse the track, and a counting means for counting the number of tracks that the light spot traverses the track,
A search control unit that controls the coarse search unit, the deceleration unit, and the fine search unit to change a track that the light spot follows according to a specified number of tracks, wherein the search control unit performs the coarse search operation. After the deceleration operation, the deceleration operation is performed, and after the deceleration operation is completed, the fine search operation is performed without closing the tracking control loop. It is a value obtained by subtracting the number of tracks counted by the counting means during operation.

According to a third aspect of the present invention, there is provided means for forming a light spot by converging a light beam on an information surface of an optical disk on which an information signal is recorded in a predetermined track form, and forming the light spot on the disk. An optical pickup comprising a tracking actuator for moving in a radial direction and a means for detecting a relative position error of the optical spot and the track in a disk radial direction by detecting reflected light from the information surface; and A tracking control unit configured to form a tracking control loop by driving the tracking actuator in accordance with the track to cause the light spot to follow the track; and a coarse search unit performing a coarse search operation to phase the optical pickup in a disk radial direction. Detects the relative speed of movement of the light spot and the track Moving state detection means, a fine search means for performing a fine search operation of causing the light spot to traverse the track at a predetermined cycle by driving the tracking actuator in accordance with an output of the moving state detection means, and Counting means for counting the number of tracks that the spot traverses the track; and search control means for controlling the coarse search means and the fine search means to change the track followed by the light spot according to the designated number. The search control means performs the fine search operation without closing the tracking control loop after the coarse search operation is completed, and the number of track crossings in the coarse search operation is a predetermined value N (where N is an arbitrary number) from the specified number. (Natural number) is subtracted, and the number of track crossings in the fine search operation is the predetermined value N. .

According to a fourth aspect of the present invention, in the third aspect, the predetermined value N is varied according to a search speed or a search distance. Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1) FIG. 1 shows an optical disk drive according to a first embodiment of the present invention. 1-8,
11, 13 to 16 are the same as those in FIG.

Reference numeral 17 denotes a controller for controlling the entire search operation. Reference numeral 18 denotes an address signal input of the controller 17;
9 is a step feed number output of the controller 17, 22 is a timing signal output for storing the total number of track traversals during the coarse search operation, and 23 is a track traverse targeted by the entire search operation including the coarse search and the fine search. The number output, 24 is a control signal output to the selection means 10, 30 is a direction detection means for detecting the relative movement direction of the light spot and the track from the signal output from the light receiving element 5, and 31 is the output of the track number counting means 7 Storage means for storing the cumulative value of the number of track crossings counted during the coarse search operation by the timing signal output 22 of the controller 17; 32, subtraction means for subtracting the output of the storage means 31 from the designated number output 23 output by the controller 17; 9 is a direction detecting means 3
The number of track crossings counted by the track number counting means 7 is reduced by the number of tracks output by the subtracting means 32 while performing cycle control so that the cycle detected by the cycle detecting means 8 becomes a predetermined cycle in accordance with the relative movement direction output by 0. This is a fine search means for performing the fine search operation by driving the tracking actuator 4 until the time becomes.

The operation of the optical disk drive of the first embodiment configured as described above will be described below with reference to FIG. FIG. 4 is a waveform diagram schematically showing the operation of the optical disc drive of the first embodiment during search control. A, B, C, D, T0, T1, and T4 are the same as those in FIG.

First, the controller 17 reads the address at the start of the coarse search from the address detecting means 16 and compares it with the address of the search target point to calculate the distance traveled in the coarse search. The converted value is designated to the coarse search means 15, and the coarse search means 15 drives the traverse mechanism 13 to move the optical pickup in the track direction (period T in FIG. 4).
1).

Here, the target number of coarse search lines does not usually coincide with the number of lines actually moved due to the step feed resolution and the eccentricity of the disk. The operation so far is the same as in the conventional example.

In the present embodiment, the controller 17 specifies the number of step feeds to the coarse search means 15 and at the same time,
The target track crossing number 23 (Nref in FIG. 4) of the entire search operation including the coarse search and the fine search is output to the subtraction means 32. Then, the total (Nrough in FIG. 4) counted by the track number counting means 7 during the coarse search operation is stored in the storage means 31 by outputting the timing signal output 22 to the storage means 31, and the coarse search is completed. At this time, the selection means 1 is controlled by the control signal 24 of the controller 17.
0 selects the output of the fine search means 9. Thus, the fine search operation is immediately started without pulling in the tracking control.

At this time, the fine search performs relative speed control, and the number of target track crossings is calculated by the subtracting means 3.
2, the number of tracks traversed by all search operations is 2
3 (Nref in FIG. 4) minus the total number of track traversals (Nrough in FIG. 4) during the coarse search operation (Nfine = Nref−Nrough in FIG. 4).

That is, the number of tracks actually traversed during the coarse search is counted while performing the coarse search operation by the step feed, and at the end of the coarse search, only the number of tracks that are different from the target number is immediately subjected to the fine search. Absorb the number of errors in the search operation. As a result, as shown in FIG. 4, the tracking control pull-in time T2 and the address reading time T3 required in FIG.
Search time can be reduced.

As described above, in the first embodiment, the coarse search means for performing the coarse search operation for moving the optical pickup in the disk radial direction, and the relative moving direction and moving speed of the light spot and the track are detected. Moving state detecting means,
Fine search means for performing a fine search operation for causing a light spot to cross a track at a predetermined cycle by driving a tracking actuator in accordance with the output of the moving state detecting means; and a counting means for counting the number of tracks that the light spot crosses the track And a search control means for controlling the coarse search means and the fine search means to change the track followed by the light spot in accordance with the designated number, and the search control means is provided after the coarse search operation is completed. The fine search operation is performed without closing the tracking control loop, and the number of tracks traversed in the fine search operation is set to a value obtained by subtracting the number of tracks counted by the counting means during the coarse search operation from the specified number. When searching, the pull-in time of tracking control and address reading time between the fine search operation and the fine search operation are unnecessary. It is possible to shorten the.

(Embodiment 2) Next, a second embodiment of the present invention will be described. FIG. 2 is a block diagram of an optical disk drive according to a second embodiment of the present invention. 1
9, 11, 13 to 16, 30, and 32 are the same as those in FIG. 1 of the first embodiment, and a description thereof will be omitted.

17 is a controller for controlling the entire search operation, 18 is an address signal input of the controller 17, 1
9 is a step feed number output of the controller 17, 25 is a timing signal output for storing the accumulated value of the number of track crossings during the coarse search operation and the deceleration operation, and 23 is a full search operation combining the coarse search and the fine search. 26, a control signal output to the selection means 35; 27, an input terminal to which the controller 17 inputs an output signal of the cycle detection means 8; 33, an output of the track number counting means 7; Storage means for storing the cumulative value of the number of track crossings counted during the coarse search operation and the deceleration operation by the timing signal output 25 of
34 is a deceleration means for reducing the relative movement speed between the light spot and the track by driving the tracking actuator 4 with the outputs of the period detection means 8 and the direction detection means 30 as inputs, and 35 is a control signal output 26 of the controller 17.
Selection means for selecting the output of the tracking control means 6, the output of the fine search means 9, the output of the deceleration means 34, and the ground level in accordance with.

The operation of the optical disk drive according to the second embodiment configured as described above will be described below with reference to FIG. FIG. 5 is a waveform diagram schematically showing an operation of the optical disc drive according to the second embodiment during search control. A, B, C, D, T0, T1, T4, N
Since ref is the same as that of FIG. 4 showing the waveform of the first embodiment, the description is omitted. T1 'is a deceleration period in which the relative moving speed of the light spot and the track is decelerated by the deceleration means 34, Nrough' is an accumulated value of the number of crossings during the coarse search operation and the deceleration operation, and Nfine is a number of crossings during the fine search operation. Show.

First, the controller 17 reads the address at the start of the coarse search from the address detecting means 16 and compares it with the address of the search target point to calculate the distance traveled in the coarse search. The rough search means 15 is converted and designated, and the rough search means 15 drives the traverse mechanism 13 in response to this to move the optical pickup in the track direction (FIG. 5).
Period T1).

The controller 17 designates the number of step feeds to the coarse search means 15 and, at the same time, the target track traversal number 23 for all search operations including the coarse search and the fine search.
(Nref in FIG. 5) is output to the subtraction means 32. And
The number of tracks actually traversed is counted by the track number counting means 7 during the coarse search operation. The operation so far is the same as in the first embodiment.

However, as described in the description of the conventional example, if the moving speed of the optical pickup during the coarse search is increased or the eccentricity of the disk is increased in order to reduce the search time, the light spot at the end of the coarse search will be lost. The relative moving speed of the truck increases. Therefore, if the fine search operation is started immediately, the speed control error during the fine search operation becomes large, and the operation may become unstable. Therefore, in the present embodiment, when the coarse search operation is completed,
The selection means 35 selects the output of the deceleration means 34 in response to the control signal 26 of. The direction detecting means 30 detects the relative moving direction of the light spot and the track, and the cycle detecting means 8 detects the relative moving cycle.
The relative speed between the light spot and the track can be reduced by applying a deceleration force to the tracking actuator 4 in a direction opposite to the direction detected by 0 and in inverse proportion to the cycle outputted by the cycle detection means 8 (FIG. Period T of 5
1 ').

The controller 17 causes the selection means 35 to select the output of the fine search means 9 by the control signal 26 when the cycle inputted from the input terminal 27 becomes larger than a predetermined value. Thus, the fine search operation is always started when the relative speed is within the predetermined range, so that the stability of the fine search operation can be improved. The accumulated value (Nrough 'in FIG. 5) of the number of track crossings during the coarse search operation and the deceleration operation is stored in the storage means 33 by the timing signal 25 of the controller 17, and the subtraction means 32 performs the entire search operation outputted by the controller 17. The output of the storage means 33 is subtracted from the target number of track traversals 23 (Nref in FIG. 5), and this is set as the target number of fine search operations (Nfine = Nref-Nrough 'in FIG. 5), thereby decelerating. Since the fine search operation including the number error generated during the operation can be absorbed, the search accuracy does not deteriorate.

As described above, in the second embodiment, the coarse search means for performing the coarse search operation for moving the optical pickup in the radial direction of the disk, and the relative moving direction and moving speed of the light spot and the track are detected. Moving state detecting means,
A deceleration means for performing a deceleration operation for reducing the relative movement speed between the light spot and the track by driving the tracking actuator in accordance with the output of the movement state detection means, Fine search means for performing a search operation, counting means for counting the number of tracks that the light spot traverses the track, and control of the coarse search means, deceleration means and fine search means so that the track that the light spot follows follows the specified number. The search control means performs a deceleration operation after completion of the coarse search operation, performs a fine search operation without closing the tracking control loop after completion of the deceleration operation, and performs a fine search operation. The number of tracks traversing the operation is counted from the specified number during coarse search operation and deceleration operation. By subtracting the number of tracks counted by the means, it is possible to shorten the search time by eliminating the pull-in time and address reading time of the tracking control between the coarse search operation and the fine search operation, and to reduce the optical time during the coarse search. Even when the pickup is moved at a high speed or the eccentricity of the disk is large, a stable and high-speed search operation can be realized.

(Embodiment 3) Next, a third embodiment of the present invention will be described. FIG. 3 is a block diagram of an optical disk drive according to the third embodiment of the present invention. 1 to 8, 10 to 11, and 30 are the same as those of the first embodiment shown in FIG.

Reference numeral 17 denotes a controller for controlling the entire search operation. Reference numeral 18 denotes an address signal input of the controller 17;
3 is a coarse search command signal for the coarse search means 42;
Is a track number counting signal input of the controller 17;
Is a direction detection signal input of the controller 17, 46 is a target number output of the fine search operation which the controller 17 gives to the fine search means 9, 47 is a control signal which the controller 17 gives to the selection means 10, and 40 is a condenser lens 3 and a tracking actuator. A traverse mechanism for transporting an optical pickup including the optical pickup 4 and the light receiving element 5 in the radial direction of the disc;
Reference numeral 41 denotes a DC motor with a brush for driving the traverse mechanism 40, and reference numeral 42 denotes a coarse search means for driving the DC motor 41 in accordance with a coarse search command signal 43 of the controller 17.

The operation of the optical disk drive according to the third embodiment configured as described above will be described below with reference to FIG. FIG. 6 is a waveform diagram schematically showing an operation of the optical disk drive according to the third embodiment during search control. A, B, D, T0, T1, T4, Nref
Are the same as those in the waveform diagram 4 of the first embodiment, and the description is omitted.

E is a drive voltage waveform of the brushed DC motor for driving the traverse mechanism, and Nfine is a preset fine search number. In the conventional example, the first embodiment, and the second embodiment, since the motor for driving the traverse mechanism is a stepping motor, positioning by open control can be basically performed. However, in the third embodiment, positioning using open control is difficult because a brushed DC motor is used. Therefore, the coarse search operation is performed by counting the number of track traversals in the same manner as the fine search operation, and a predetermined number of target tracks (FIG. 6).
Nfine) Switch to the fine search operation before this.

This operation will be described in more detail. First, the controller 17 reads the address at the start of the coarse search from the address detection means 16, compares it with the address of the search target point, and searches for the number of search targets (N in FIG. 6).
ref), and instructs the coarse search means 42 to start the coarse search by the coarse search command signal 43. Rough search means 4
2 applies a predetermined voltage (E in the period T1 in FIG. 6) to the DC motor 41, and moves the optical pickup in the track direction by the traverse mechanism 40 (period T1 in FIG. 6).

The controller 17 monitors the number of tracks actually traversed by the output of the track number counting means 7 during the coarse search operation. At this time, if the relative movement direction between the light spot and the track is reversed from the search target direction due to the influence of the eccentricity of the disk or the vibration of the tracking actuator according to the output of the direction detection means 30, the number of track movements is compensated by subtracting it. Thereby, the number error can be reduced.

The controller 17 determines that the actual number of track crossings during the coarse search operation is the search target number (Nre in FIG. 6).
f) The number of fine search preset from (fine in Fig. 6)
When it is detected that the number (Nref−Nfine) has been subtracted from the coarse search command signal 43, the coarse search means 4
2, the coarse search operation is terminated, and at the same time, the selection means 10 is caused to select the output of the fine search means 9 by the control signal 47 to start the fine search operation. At this time, the controller 17
Since the fine search target number output 46 (Nfine in FIG. 6) is preset in the fine search means 9, the fine search number is Nfine. In this way, the search target number of Nfi
neBecause the mode is switched to the fine search operation before this, unnecessary operations such as overrunning the target track during the coarse search operation and returning in the reverse direction in the fine search operation can be prevented, and the search time can be reduced. it can.

The predetermined fine search number Nfine may be a fixed value in the system, but may be a target track for the entire search operation according to the traverse moving speed or distance during the coarse search or the entire search operation combining the coarse search and the fine search. It may be made to be variable by the controller 17 according to the number of crossings. The number of fine searches Nfine is preferably as small as possible from the viewpoint of the required search time and the movable range of the tracking actuator. However, if the relative movement speed between the light spot and the track at the start of the fine search is high, the fine search operation is completed. In some cases, the relative speed error cannot be sufficiently compressed before the search is performed, and the pull-in of the tracking control at the end of the fine search may become unstable. In order to avoid this, the controller 17 increases the fine search number Nfine when the traverse travel distance or speed is large, and decreases the fine search number Nfine when the traverse travel distance or speed is small, thereby starting the fine search. Even when the relative speed at the time is high, the relative speed error can be sufficiently compressed until the fine search operation is completed, and the pull-in of the tracking control can be stabilized.

As described above, in the third embodiment, the coarse search means for performing the coarse search operation for moving the optical pickup in the disk radial direction, and the relative moving direction and moving speed of the light spot and the track are detected. Moving state detecting means,
Fine search means for performing a fine search operation for causing a light spot to cross a track at a predetermined cycle by driving a tracking actuator in accordance with the output of the moving state detecting means; and a counting means for counting the number of tracks that the light spot crosses the track And a search control means for controlling the coarse search means and the fine search means to change the track followed by the light spot according to the designated number, and the search control means performs tracking after the coarse search operation is completed. The fine search operation is performed without closing the control loop. The number of track crossings in the coarse search operation is a value obtained by subtracting a predetermined value N (N is an arbitrary natural number) from the specified number. The predetermined value N varies between the coarse search operation and the fine search operation by being varied according to the search speed or the search distance. The tracking pull-in time and address reading time become unnecessary, and at the same time, the search operation is shortened by preventing useless operations such as overrunning the target track during the coarse search operation and returning in the reverse direction in the fine search operation. Further, even when the traverse movement speed at the time of the coarse search is high or the eccentricity of the disk is large, the pull-in of the tracking control at the end of the fine search can be stabilized.

In all of the embodiments of the present invention, each process to be performed electrically may be an analog circuit that directly processes an analog signal, or may be A / D converted and digitally processed. Is also good. In the case of digital processing, processing may be performed by hardware of a digital circuit, or processing may be performed by software such as a DSP or a microcomputer.

For example, in the embodiment of the present invention, the fine search means 9, the coarse search means 15, the selection means 10 or 35 are provided, and the control thereof is performed by the controller 17, but all of these means or A part may be configured by a controller, and the controller may be software such as a microcomputer or a DSP, or hardware such as a sequencer. There is no change.

In all the embodiments of the present invention, the direction detecting means 30 may be any type as long as it detects the relative movement direction between the light spot and the track. In general, the tracking error signal and the information signal are used. Can be realized by comparing the phases of the envelopes (or the total reflected light amounts). Alternatively, the direction detecting means 30 can be omitted, and in that case, the gist of the present invention is not changed at all.

Further, in the second embodiment of the present invention, the speed reducing means 34 may be any type as long as it reduces the relative moving speed between the light spot and the track. The method is not limited to the method of applying the driving force inversely proportional to the relative movement cycle as in the second embodiment, and various methods such as applying a constant pulse value as long as the relative movement direction can be detected.

In all of the embodiments of the present invention, the fine search means 9 detects the zero-cross period of the tracking error signal and controls the period so that the zero-cross period becomes a predetermined value. Any configuration may be used as long as it can control the relative movement speed with respect to the track. For example, the configuration is such that the tracking error signal is subjected to F / V (frequency / voltage) conversion to detect the relative speed and control the speed. Is also good.

In the selection means 10 in the first and third embodiments of the present invention and the selection means 35 in the second embodiment, one of the inputs is a ground level. It is not necessary to be at the ground level because it is for opening the loop. It may be a predetermined reference voltage level, or a predetermined numerical value in the case of digital processing. Further, a driving force for suppressing the vibration of the tracking actuator during the coarse seek may be applied, or a vibration of the tracking actuator may be directly or indirectly detected and fed back.

Further, in the first and second embodiments of the present invention, the motor for driving the traverse mechanism is a stepping motor. However, a structure capable of positioning by open control (a hall motor, a motor with an FG & encoder, a position sensor) The same processing is possible if it is a mechanism that has an FG or a position sensor, such as a motor with a DC brush or a voice coil motor that does not have an FG or position sensor. The same processing can be performed by predicting or learning the distance traveled by using the above method, or by using a fixed value. In any case, there is no change in the spirit of the present invention.

In the third embodiment of the present invention, the traverse mechanism is a motor with a DC brush. However, not only a stepping motor but also a mechanism for moving the optical pickup in the radial direction of the disk.
Exactly the same process is possible with any motor and mechanism.

In the first and second embodiments of the present invention, the profile of the rotation speed of the stepping motor at the time of the coarse search has a triangular waveform, but a constant speed, a trapezoidal waveform, or a waveform that changes more smoothly. For example, any waveform may be used.

Further, in the third embodiment of the present invention, the drive voltage waveform of the DC motor at the time of the coarse search is a constant voltage, but this may also be a triangular wave, trapezoidal wave, or a combination of acceleration / deceleration. , Any driving waveform may be used.

[0057]

As described above, the present invention provides a coarse search means for performing a coarse search operation for moving an optical pickup in the radial direction of a disk, and a moving state for detecting a relative moving direction and a moving speed of a light spot and a track. Detecting means, fine search means for performing a fine search operation of driving the tracking actuator in accordance with the output of the moving state detecting means to cause the light spot to cross the track at a predetermined cycle, and the number of tracks which the light spot crosses the track And a search control means for controlling the coarse search means and the fine search means to change the track followed by the light spot in accordance with the designated number. After the operation is completed, the fine search operation is performed without closing the tracking control loop, and the number of tracks traversed in the fine search operation is specified. By subtracting the number of tracks counted by the counting means during the coarse search operation from the number, the pull-in time of the tracking control between the coarse search operation and the fine search operation is unnecessary, and the search time can be reduced. .

[Brief description of the drawings]

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

FIG. 2 is a block diagram of an optical disk drive according to a second embodiment of the present invention;

FIG. 3 is a block diagram of an optical disk drive according to a third embodiment of the present invention;

FIG. 4 is a waveform chart showing waveforms during a search operation according to the first embodiment of the present invention.

FIG. 5 is a waveform chart showing waveforms during a search operation according to the second embodiment of the present invention.

FIG. 6 is a waveform chart showing waveforms during a search operation according to the third embodiment of the present invention.

FIG. 7 is a block diagram of an optical disk drive in a conventional example.

FIG. 8 is a waveform diagram showing a waveform during a search operation in a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical disk 2 Rotation means 3 Objective lens 4 Tracking actuator 5 Light receiving element 6 Tracking control means 7 Track number counting means 8 Period detection means 9 Fine search means 10 Selection means 15 Rough search means 17 Controller 31 Storage means 32 Subtraction means 33 Storage means 34 Reduction means 35 Selection means 42 Rough search means

Claims (4)

[Claims] A means for forming a light spot by converging a light beam on an information surface of an optical disk on which an information signal is recorded in a predetermined track form; a tracking actuator for moving the light spot in a disk radial direction; An optical pickup including means for detecting a relative position error between the light spot and the track in a disk radial direction by detecting light reflected from an information surface; and driving the tracking actuator according to the relative position error. A tracking control means for forming a tracking control loop to cause the light spot to follow the track; a coarse search means for performing a coarse search operation for moving the optical pickup in a disk radial direction; and a relative position between the light spot and the track. Moving state detecting means for detecting a dynamic moving speed; Fine search means for performing a fine search operation of causing the light spot to cross the track at a predetermined cycle by driving the tracking actuator in accordance with the output of the moving state detecting means; and a track where the light spot crosses the track. Counting means for counting the number of tracks, and search control means for controlling the coarse search means and the fine search means to change the track followed by the light spot in accordance with a designated number, and wherein the search control means comprises After the search operation is completed, the fine search operation is performed without closing the tracking control loop, and the number of tracks traversed in the fine search operation is obtained by subtracting the number of tracks counted by the counting means during the coarse search operation from the specified number. An optical disk drive, wherein the value is a value obtained by subtraction. 2. A means for converging a light beam on an information surface of an optical disc on which an information signal is recorded in a predetermined track form to form a light spot, a tracking actuator for moving the light spot in a radial direction of the disc, and An optical pickup including means for detecting a relative position error between the light spot and the track in a disk radial direction by detecting light reflected from an information surface; and driving the tracking actuator according to the relative position error. A tracking control means for forming a tracking control loop to cause the light spot to follow the track; a coarse search means for performing a coarse search operation for moving the optical pickup in a disk radial direction; and a relative position between the light spot and the track. Moving state detecting means for detecting a dynamic moving speed; Decelerating means for performing a decelerating operation to reduce a relative moving speed of the light spot and the track by driving a tracking actuator in accordance with an output of a moving state detecting means; and Fine search means for performing a fine search operation of traversing a track; counting means for counting the number of tracks in which the light spot crosses the track; controlling the coarse search means, the deceleration means, and the fine search means, Search control means for changing the track that the light spot follows according to the specified number of tracks, the search control means performs the deceleration operation after the coarse search operation ends, and executes the tracking control loop after the deceleration operation ends. Perform the fine search operation without closing, and An optical disk drive, wherein the number of traversing tracks is a value obtained by subtracting the number of tracks counted by the counting means during the coarse search operation and the deceleration operation from the specified number of tracks. 3. A means for converging a light beam on an information surface of an optical disc on which an information signal is recorded in a predetermined track form to form a light spot, a tracking actuator for moving the light spot in a radial direction of the disc, and An optical pickup including means for detecting a relative position error between the light spot and the track in a disk radial direction by detecting light reflected from an information surface; and driving the tracking actuator according to the relative position error. A tracking control means for forming a tracking control loop to cause the light spot to follow the track; a coarse search means for performing a coarse search operation for moving the optical pickup in a disk radial direction; and a relative position between the light spot and the track. Moving state detecting means for detecting a dynamic moving speed; Fine search means for performing a fine search operation of causing the light spot to cross the track at a predetermined cycle by driving the tracking actuator in accordance with the output of the moving state detecting means; and a track where the light spot crosses the track. Counting means for counting the number of tracks, and search control means for controlling the coarse search means and the fine search means to change the track followed by the light spot in accordance with a designated number, and wherein the search control means comprises After the search operation is completed, the fine search operation is performed without closing the tracking control loop, and the number of track crossings in the coarse search operation is a value obtained by subtracting a predetermined value N (N is an arbitrary natural number) from the specified number of tracks. An optical disk drive, wherein the number of track crossings in the fine search operation is the predetermined value N. 4. A means for forming a light spot by converging a light beam on an information surface of an optical disk on which an information signal is recorded in a predetermined track form, a tracking actuator for moving the light spot in a disk radial direction, and An optical pickup including means for detecting a relative position error between the light spot and the track in a disk radial direction by detecting light reflected from an information surface; and driving the tracking actuator according to the relative position error. A tracking control means for forming a tracking control loop to cause the light spot to follow the track; a coarse search means for performing a coarse search operation for moving the optical pickup in a disk radial direction; and a relative position between the light spot and the track. Moving state detecting means for detecting a dynamic moving speed; Fine search means for performing a fine search operation of causing the light spot to cross the track at a predetermined cycle by driving the tracking actuator in accordance with the output of the moving state detecting means; and a track where the light spot crosses the track. Counting means for counting the number of tracks, and search control means for controlling the coarse search means and the fine search means to change the track followed by the light spot in accordance with a designated number, and wherein the search control means comprises After the search operation is completed, the fine search operation is performed without closing the tracking control loop, and the number of track crossings in the coarse search operation is a value obtained by subtracting a predetermined value N (N is an arbitrary natural number) from the specified number of tracks. The number of track crossings in the fine search operation is the predetermined value N, and the predetermined value N is a search speed or a search speed. Optical disk drive apparatus characterized by being varied depending on the release.