JP2948926B2 - Disk seeker - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information recording / reproducing apparatus for recording / reproducing information on / from a disk having tracks on which information is recorded or recorded.

[0002]

2. Description of the Related Art An optical information recording / reproducing apparatus is one of suitable recording / reproducing apparatuses to which the present invention is applied.

[0003] With respect to a conventional optical information recording / reproducing apparatus,
This will be described with reference to FIG. As shown in FIG. 4, a light beam generated from a light source 51 such as a semiconductor laser passes through a coupling lens 52 and a beam splitter 53, is reflected by a reflecting mirror 54, and is condensed by a converging lens 55.
7 is irradiated. The motor 58 rotates the recording medium 57 at a predetermined rotation speed. Tracking actuator 56
Has a configuration in which a converging lens is moved in a radial direction of a recording medium (a direction substantially perpendicular to a track). Further, the split photodetector 59 converts the reflected light from the recording medium 57 into an electric signal, and outputs each signal to the differential amplifier 60 and a synthesizing circuit 61 for reading information such as a track number. . The differential amplifier 60 outputs the signal from the split photodetector 59 to the waveform processing circuit 62 and the switch 63 as a tracking error signal (TES). TES
Is input to a tracking actuator 56 for performing tracking control via a switch 63, a phase compensation circuit 64, and a drive circuit 67. Also, TES is
Combining circuit 68 via switch 63 and phase compensation circuit 65
The output signal of the synthesizing circuit 68 is input to a driving circuit 70 for driving a linear motor 69.
During the tracking control, the linear motor 69 is driven so that the signal of the drive circuit 70 becomes zero level on average to perform the transfer control in order to prevent the transfer table 71 from being largely displaced and the tracking control being deviated. I have. So-called two-stage servo control is performed.

A signal from a speed detector 72 that outputs a signal corresponding to the moving speed of the transfer table 71 is input to the synthesizing circuit 68 and the counting circuit 74, respectively. The counting circuit 74
Counts the output signal obtained by shaping the TES signal by the waveform processing circuit 62, and outputs the counted output to a signal generation circuit 75. The signal generation circuit 75
A signal is output to the synthesizing circuit 68. The synthesis circuit 68
The speed signal of the transfer table 71 of the speed detector 72, the output signal of the phase compensation circuit 65, and the signal generation circuit 75
For synthesizing the signal output via the.

When this device performs a seek operation, when a desired track number A0 is input to an address input device 77, an information processing control device 78 causes a light beam to be positioned on the recording medium 57 by a read signal of the synthesizing circuit 61. The current track number Al is read. The information processing control device 78
-A0 | is output to the counting circuit 74. Then, the information processing control device 78 gives a switching instruction to the switch 76, and outputs a seek command to the counting circuit 74. The signal generating circuit 75 outputs | Al-A0 |
A movement amount signal corresponding to the counter value k is generated. The signal generation circuit 75 outputs a movement amount signal to the linear motor 69 via the switch 76, the synthesizing circuit 68, and the driving circuit 70, and the linear motor 69 drives the transfer table 71, and the transfer table 71 starts to move.

On the other hand, the counting circuit 74 delays a seek command by an internal delay circuit, and this delayed signal is input to the information processing control device 78. By the way, the information processing control device 7
Until the delay signal is input to 8, tracking control,
The light beam on the recording medium 57 is stably positioned on a predetermined track by the two-step servo control. When the delay signal is input, the information processing control device 78 switches the switch 63 to stop the tracking control and the transfer control. While the transfer table 71 is moving, the differential amplifier 60 outputs TESs for the number of light beams crossing the tracks on the recording medium 57, and the waveform processing circuit 62 binarizes the TESs and counts them. Output to the circuit 74. The counting circuit 74 has a binarized TES
Is output to the signal generation circuit 75. The signal generating circuit 75 generates a signal corresponding to the count value of the counting circuit 74 and controls the moving speed of the transfer table 71.

The counting circuit 74 outputs the light beam to the recording medium 57.
Count the number of tracks that crossed the upper track, and | A1−
A0 | It detects that the light beam has reached the track of the current track, and outputs a coincidence signal m to the information processing control device 78.
The information processing control device 78 opens the switch 76 to stop the linear motor 69, and the information processing control device 78 short-circuits the switch 63 to operate the tracking control and the transfer control, and the light beam on the recording medium 57. A2 is read from the track number where is located. If A2 = A0, the seek is terminated; if | A2-A0 | ≥N, the coarse seek is performed; if | A2-A0 | <N, the fine seek is performed via the tracking actuator 56. ,
Move the light beam to the desired track.

[0008]

However, in the conventional apparatus, when performing a seek operation, a track keeping operation is performed by a tracking actuator. In order to eliminate the influence of the above, the track keeping operation by the tracking actuator is released after a delay of a certain time until the linear motor starts to accelerate. Therefore, if the acceleration sensitivity of the linear motor is lower than the standard value due to variations in the linear motor, the linear motor cannot be sufficiently accelerated within the delay time, and the speed of the linear motor loses to the eccentric speed of the disk. There is a disadvantage that the track traversed by the light beam is miscounted. If the acceleration sensitivity of the linear motor is higher than the standard value, the linear motor will be accelerated too much within the delay time, and will exceed the servo controllable range of the tracking actuator. There is a disadvantage that it will.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has no influence on the rotational eccentricity of a disk and the like, and is not affected by the variation in the acceleration sensitivity of a coarse moving means such as a linear motor. It is an object of the present invention to provide a disk seek device capable of accurately measuring a track traversed by an upper light beam and performing an accurate seek operation.

[0010]

According to the present invention, there is provided a disk seek apparatus for performing at least one of recording and reproduction of information by scanning a light spot on a disk having a plurality of tracks on which information is recorded. In the optical information recording and reproducing apparatus of the fine movement means for displacing the light spot in a direction crossing the track of the disk,
Coarse movement means for moving the scanning position of the light spot across the track of the disk, including the fine movement means, and detecting a relative position shift between the light spot and the track to generate a track error signal; A track error detecting means for outputting, and at least one of a position and a speed of the fine moving means in a direction crossing the track provided in the coarse moving means to output at least one of the position signal or the speed signal Detecting means, and at least one of a position signal and a speed signal output by the detecting means at the time of seeking, and in a state where the coarse moving means starts accelerating in the target track direction, the output signal of the detecting means is monitored. The fine moving means performs the track keeping operation until at least one of them reaches a preset value, and When it exceeds, the track keeping operation by the fine moving means is released, the number of tracks crossed by the light spot is counted from the track error signal output by the track error detecting means, and the coarse moving means and the fine moving means are controlled. Means.

[0011]

With this configuration, the control means monitors at least one of the position signal and the speed signal output by the detection means at the time of seeking, and performs the detection while the coarse movement means starts accelerating in the target track direction. Until at least one of the output signals of the means reaches a preset value, the fine moving means performs the track keeping operation, and when exceeding the set value, cancels the track keeping operation by the fine moving means, The number of tracks crossed by the light spot is counted from the track error signal provided by the track error detecting means, and the coarse moving means and the fine moving means are controlled.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of an apparatus according to a first embodiment of the present invention. As shown in FIG. 1, an optical information recording / reproducing apparatus 1 for recording or reproducing information on or from a disk 2 having a plurality of tracks (not shown) for recording or recording information is shown. The optical information recording / reproducing apparatus 1 includes a seek device for moving a light spot to a target track on a disk 2.

The optical head 3 has an objective lens 4 for irradiating the disk 2 with light emitted from a light source as a light spot.
This is for writing information to the disk 2 or reading information from the disk 2. The optical head 3 internally has a tracking actuator 5 as a fine moving means for deflecting the objective lens 4 in a direction crossing the track of the disk 2, while a TES photodetector 6 for detecting a tracking error signal (TES). have. The optical head 3 also includes an information detecting light detector 7 for detecting information on the disk 2 and a position detector 8 as a detecting means for detecting a position of the objective lens 4 in a direction crossing the track. . The optical head 3 is moved in a direction crossing the tracks of the disk 2 by a voice coil motor (VCM) 9 as a coarse moving means. The disk 2 is rotated at a predetermined rotation speed by a motor (not shown).

An information signal detection circuit 10 reproduces information of the disk 2 detected by the information detection photodetector 7 as an RF information signal, and an address detection circuit 11 reads a track number from the RF information signal to read a control signal to be described later. Output to the circuit 12 is provided.

The tracking actuator 5 has a T
The TES output from the ES photodetector 6 is changed to the first switch 1
2, a first phase compensation circuit 13 for compensating the phase of TES,
The signals are input via the adder 14 and the actuator driver 15 and constitute a tracking loop for performing tracking servo control so that the objective lens 4, that is, the light spot keeps a predetermined track. Further, the VCM 9 inputs the position signal output from the position detector 8 via a third phase compensation circuit 16, a third switch 17, and a VCM driver 18 for compensating the phase of the signal. Tracking actuator 5
Constitutes a transfer control loop for driving the VCM 9 to move around the natural state. That is, the servo movable range in which tracking servo is applied, that is, the range in which the tracking actuator 5 can move is, for example, about 500 μm, and so-called two-step servo is applied so that tracking control due to eccentricity of disk rotation does not deviate. . Further, the VCM driver 18 outputs the position signal subjected to the phase compensation to the reaction compensation circuit 19. Then, the reaction correction circuit 19
The position signal output from the VCM driver 18 is received, via the fourth switch 20, the adder 14, and the actuator driver 15, so as to eliminate the influence of the inertial force generated in the tracking actuator 5 when the VCM 9 moves. Correction is performed. These position detector 8, third phase compensation circuit 16, third switch 1
7, a VCM driver 18, a reaction correction circuit 19, an adder 14, an actuator driver 15, and a tracking actuator 5 constitute a reaction correction loop. The three loops described above operate simultaneously in tracking control, that is, in a track keeping state.

On the other hand, a control 12 as control means
Inputs the target track number of the movement destination set by the target track setting circuit 21, and the light spot is currently located via the information light detector 7, the information signal detection circuit 10, and the address detection circuit 11. The track number and input. The control 12 includes a third switch 17 and a VCM driver 18
, The movement amount corresponding to the difference between the target track number and the current track number is given to the VCM 9, and the VCM 9 causes the light spot to reach the target track. The control circuit 12 monitors the position signal output from the position detector 8, and switches a predetermined switch to cancel the track keep state when the position signal exceeds a preset position. Accordingly, the tracking actuator 5 inputs the position signal output from the position detector 8 via the second phase compensation circuit 22 for compensating the phase of the signal, the second switch 23, and the actuator driver 15, and seeks. When the VCM 9 moves inside, the objective lens 4 is locked so as not to be displaced from a reference position, and these constitute a steady-back servo loop. On the other hand, the track cross signal detection circuit 24
Is for binarizing the TES output from the TES photodetector 6 and outputting it to the control circuit 12. The control circuit 12 counts the number of track cross pulses output from the track cross signal detection circuit 24, monitors the difference from the target track, that is, the position of the currently passing track (distance to the target track), and monitors the target track. Speed control signal according to the distance of the VCM driver 1
8 to the VCM 9. Accordingly, the speed of the VCM 9 is controlled by the control circuit 12 according to the distance to the target track during the seek. Further, when the control circuit 12 detects that the number of track cross pulses to be counted matches the target track number, the control circuit 12 instructs a predetermined switch to switch, and
It returns to the track keep state. In the track keeping state, the first switch 12, the second switch 23, the third switch 17, and the fourth switch 20 are turned on to the side a.

The objective lens 4 is driven by a focusing actuator (not shown).
Focus servo control is performed so that the light spot is focused on the top. Further, the control circuit 12 gives the movement amount for the fine seek to the actuator driver 15 by a signal line (not shown), and finely seeks the objective lens 4 via the track actuator 5.

The operation of the embodiment will be described. At the start of the seek, the control circuit 12 controls the first switch 1
2 and the second switch 23 is turned on to the
And outputs a switching instruction to turn on the switch 17 and the fourth switch 20 to the b side. Control 1
2 outputs the movement amount corresponding to the difference between the given target track number of the movement destination and the current track number to the VCM 9 via the VCM driver 18, and the VCM 9 starts acceleration in the direction of the target track. At this time, the objective lens 4
Track keeping operation is performed by the tracking loop. By the way, as the VCM 9 moves,
The tracked objective lens 4 is left behind in the direction opposite to the seek direction, and exceeds the servo controllable range. Therefore, the control circuit 12 monitors the position signal output from the position detection circuit 8, and when the position signal exceeds the preset position, that is, before the servo control range is exceeded,
The first switch 12 is turned on to the b side to release the tracking keep state, while the third switch 17 is turned on to the b side, and the fourth switch 20 is set to the a side. The objective lens 4 is locked by the loop. At the same time, the control 12
Switch 23 is turned on, the number of track cross pulses output by the track cross signal detection circuit 24 is counted, and according to the difference between the count value and the target track number, V
Via the CM driver 18, the speed of the VCM 9 is controlled according to the distance to the target track. Control circuit 1
2 turns on the first switch 12, the second switch 23, the third switch 17, and the fourth switch 20 to the a side when the target track and the count value match, and The track is turned on and the tracking state including the two-step servo and reaction correction control is completed to complete the coarse seek operation. Next, the control circuit 12 reads the current track number N1 from the address detection circuit 11 and judges whether or not the current track number N1 has been reached. When N1 = N0, the seek operation is terminated, while | N1-N0. When | ≦ α, fine seek is performed via the tracking actuator 5, and when | N1−N0 |> α, coarse seek is performed again. The predetermined value α is a preset number of tracks, and is set to, for example, a coarse seek error.

In this embodiment, when the seek operation is performed,
The control 12 monitors the position of the objective lens 4 by the position signal, cancels the track keeping state before the servo controllable range is exceeded, and counts the number of tracks crossed by the light spot. It is possible to prevent the number of tracks from being erroneously counted because the servo is not applied beyond the servo controllable range without being affected by the core or the like, and therefore, an accurate seek operation can be performed. Also, if a specific VCM 9 is used,
When the variation in the acceleration sensitivity of the VCM 9 used is small, the acceleration is accelerated to a predetermined speed within the servo controllable range, so that the speed of the linear motor is not lost to the eccentric speed of the disk, and the light spot is formed. Miscounting of the number of traversed tracks can also be prevented, so that an accurate seek operation can be performed.

FIG. 2 is a block diagram of an apparatus according to a second embodiment of the present invention. In this embodiment, the timing at which the tracking servo is turned off is controlled based on the position detection in the first embodiment, but the timing is switched by speed detection instead of position detection. In addition, the same components and operations as those of the first embodiment are denoted by the same reference numerals, description thereof will be omitted, and illustration in FIG. 2 will be omitted.

As shown in FIG. 2, a differentiating circuit 30 as a detecting means differentiates the position signal output from the position detector 8 and outputs the result as a speed signal of the objective lens 4 to the control circuit 1.
2A. Control circuit 1
2A is for monitoring the speed signal at the time of seek and canceling the track keep state when the speed exceeds a predetermined speed (sufficient speed for not miscounting the number of tracks crossed by the light spot). Each of the above-mentioned switches is switched. This control circuit 12A is the same as the control circuit 12 of the first embodiment except that the speed is monitored and the predetermined switch is switched.
And the other configurations are the same.

In this embodiment, the VCM 9 starts moving to the target track, and the control circuit 12 monitors the speed signal output from the differentiating circuit 30 and cancels the track keep state when the speed exceeds a preset speed. Since the number of tracks traversed by the light spot is counted, it is not affected by the rotational eccentricity of the disk, etc., and the speed of the linear motor is less than the eccentric speed of the disk. A simple seek operation. If a specific VCM 9 is used, that is, if the variation in the acceleration sensitivity of the VCM 9 to be used is small, a predetermined speed is reached before exceeding the servo controllable range, and the track keep state is released in that state. Counting. For this reason, it is possible to prevent the number of tracks from being miscounted, and to perform an accurate seek operation.
The other configuration and operation and effect are the same as in the first embodiment, and the description is omitted.

FIG. 3 is a block diagram of an apparatus according to a third embodiment of the present invention. In the present embodiment, the timing for turning off the tracking servo is controlled based on both the position detection in the first embodiment and the speed detection in the second embodiment. In addition, the same configurations and operations as those in the first and second embodiments are denoted by the same reference numerals, description thereof will be omitted, and illustration in FIG. 3 will be omitted.

As shown in FIG. 3, a differentiating circuit 30 as a detecting means differentiates the position signal output from the position detector 8 and outputs the result as a speed signal of the objective lens 4 to the control circuit 1.
2B. Further, the position detector 8 as a detecting means detects the position of the objective lens 4 and sends it to the control circuit 12B as a position signal. The control circuit 12B monitors the previous speed signal and the position signal at the time of seeking, and switches over the predetermined switches to cancel the track keep state when the speed exceeds a predetermined speed and exceeds a predetermined position. I have. The control circuit 12B has the same configuration as the control circuit 12 of the first embodiment, except that both the speed and the position are monitored and the predetermined switch is switched.

In this embodiment, the VCM 9 starts moving to the target track, and the control circuit 12 monitors the speed signal output from the differentiating circuit 30 and exceeds the speed set in advance.
In addition, the position signal output from the position detector 8 is monitored, and when the position exceeds a preset position, the track keeping state is released, and the number of tracks crossed by the light spot is counted. Therefore, the speed of the linear motor is less than the eccentric speed of the disk, so that there is no miscount, and there is no miscount beyond the servo controllable range. That is, the control circuit 12B uses the VCM 9 to be used.
It is possible to determine whether or not the objective lens 4 has reached a sufficient speed that does not cause a miscount before exceeding the servo controllable range, even if the acceleration sensitivity varies, and to prevent miscounting of the number of tracks. Therefore, an accurate seek operation can be performed. If both or one of the conditions of the speed and the position is not satisfied, the possibility of miscounting is extremely high, so that the VCM 9 can be used as an acceleration sensitivity check or a secular change check device. Other configurations, functions and effects are the first.
This is the same as the embodiment and the second embodiment, and the description is omitted. The setting condition may be set for either the speed or the position, but is effectively the same as in the first embodiment or the second embodiment.

When a galvanomirror is used as the optical head, the fine moving means is replaced with a galvanomirror driving means instead of the tracking actuator 5, and the detecting means is replaced with the position detector 8 or the differentiating circuit 30 instead of the position detector 8.
The same effect can be obtained by a configuration having an angle detecting means or an angular velocity detecting means for detecting an angle at which the galvanomirror rotates.

[0027]

As described above, according to the present invention, the number of tracks traversed by a light beam on a recording medium during a seek operation is accurately measured without being affected by variations in the acceleration sensitivity of the coarse moving means. There is an effect that an accurate seek operation can be performed, and therefore, the seek accuracy of the apparatus can be improved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an apparatus according to a first embodiment.

FIG. 2 is a configuration diagram of an apparatus according to a second embodiment.

FIG. 3 is a configuration diagram of an apparatus according to a third embodiment.

FIG. 4 is a configuration diagram of a conventional device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Optical information recording / reproducing apparatus 2 ... Disk 3 ... Optical head 4 ... Objective lens 5 ... Tracking actuator 8 ... Position detector 9 ... VCM 11 ... Address detection circuit 12 ... Control circuit 21 ... Target track setting circuit 24 ... Track cross Signal detection circuit

Claims (1)

(57) [Claims] An optical information recording / reproducing apparatus for performing at least one of recording and reproduction of information by scanning a light spot on a disk having a plurality of tracks on which information is recorded. Fine moving means for displacing in a direction crossing the track of the disk, coarse moving means for moving the scanning position of the light spot in a direction crossing the track of the disk including the fine moving means, and the light spot; A track error detecting means for detecting a relative position shift with respect to a track and outputting a track error signal; and detecting at least one of a position and a speed of the fine moving means in a direction crossing the track provided in the coarse moving means. Detecting means for outputting at least one of the position signal and the speed signal; Monitoring at least one of the position signal or the speed signal output by the output means, and in a state where the coarse movement means has started accelerating in the target track direction, at least one of the output signals of the detection means has a preset value. Until the fine moving means performs the track keeping operation, and when the set value is exceeded, the track keeping operation by the fine moving means is released and the light spot is detected from the track error signal output by the track error detecting means. A seek device for a disk, comprising: a controller that counts the number of tracks traversed and controls a coarse moving unit and a fine moving unit.