JPH0855347A - Retrieving controller - Google Patents

Abstract

PURPOSE:To obtain a device having high reliability which can surely retrieve a desired track by securing stability for speed control, and pull-in during retrieving for temperature variation, recular change, or vibration/impact of an optical head, disk, and the like, or eccentricity of a disk. CONSTITUTION:The number of errors of retrieving and the frequency of retrying are detected. Temperature variation and vibration/impact of a device are measured by a temperature sensor 51 and an acceleration sensor 61. Eccentricity of a disk 7 is measured. Speed profile being the reference speed of next driving is switched to the optimum condition depending on conditions obtained as the above, and stability of speed control and pull-in during retrieving after that is secured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is preferably applied to an optical recording / reproducing apparatus for optically recording a signal on a recording medium or reproducing a signal on the recording medium by using a light source such as a laser. In particular, the present invention relates to a search control device for accessing a desired track with an optical beam.

[0002]

2. Description of the Related Art In recent years, an optical recording / reproducing apparatus has been required to have a high search speed, and has been gradually realized. Especially 3.5 "
For optical disk devices, the catalog value is 30 ms on average
Those that have achieved the following search times have also been commercialized.

The structure and algorithm of a conventional search control device will be described below. FIG. 17 is a block diagram showing a simple configuration of a conventional search control device.

An optical beam 6 generated from a light source 1 such as a semiconductor laser is collimated by a coupling lens 2 and then converted into parallel light.
The light is reflected by the polarization beam splitter 3, converged by the raising mirror 4 and the converging lens 5, and irradiated on the rotating disk 7 by a motor (not shown). The reflected light of the optical beam 6 from the disk 7 passes through the converging lens 5 and the rising mirror 4, the polarization beam splitter 3, and is input to the photodetector 8 having a two-division structure. Photo detector 8
The outputs a and b are amplified by preamplifiers 9a and 9b, respectively, and then input to the differential amplifier 10, and a track deviation signal (hereinafter referred to as "TE") can be obtained from the output of the differential amplifier 10.

TE is input to a gain switching circuit 11 for adjusting variations in the optical system. The gain switching circuit 11 can change the amplification factor by a variable resistor (not shown) so that the amplitude of TE at point a in FIG. 17 becomes substantially constant. The TE having a substantially constant amplitude is input to the phase compensation filter 20 for compensating the phase of the tracking control system, the switch 21 for turning on / off the control system, and the TR drive circuit 22 for amplifying power to perform tracking control element. 23 is input. As a result, the tracking control element 23 is driven so that the optical beam on the disk 7 correctly scans the track.

Further, the output TE of the gain switching circuit 11
Is also input to the low-pass filter 12 and the phase compensation filter 13, and is input to the linear motor 24 via the switch 14 for turning on / off the control system and the LM drive circuit 15 for power amplification. This allows the linear motor 24
Means that the center of the light beam and the center of the converging lens 5 coincide with each other when the light beam on the disk 7 scans the track, that is, the optical axis of the light beam convergently irradiated on the disk 7 is The transfer is controlled so as to be perpendicular to the.

Further, the output TE of the gain switching circuit 11
Is binarized in the binarization circuit 16. Therefore, the moving distance can be calculated by counting the binary signal when the light beam crosses the track. Further, the moving speed can be calculated by measuring the pulse width of this binarized signal.

The arithmetic circuit 17 calculates the moving distance and moving speed of the light beam based on the binarized signal, selectively acquires the moving speed corresponding to the distance from the speed profile table 18, and sets the reference speed Vref. Differential amplifier circuit 19
To enter. The actual moving speed Vreal is also input to the differential amplifier circuit 19, and the difference signal is input to the LM drive circuit 15 via the switch 14 and is controlled so as to have a predetermined moving speed. The switch 14 is on the side of the differential amplifier circuit 19
When N, the loop of the tracking control system is OF
Therefore, the linear motor 24 is driven while controlling at a predetermined speed based on a predetermined speed profile table to search for a desired track.

The search flow in the configuration of FIG. 17 will be described in more detail. When a read / write or search command is issued from the host computer, the difference between the target address of the desired track of the arithmetic circuit 17 and the address of the track where the current light beam is located, that is, the moving distance of the light beam at the time of search The reference speed is set from the speed profile table 18 in accordance with the above. After that, the tracking control is turned off, the acceleration (deceleration) signal from the differential amplifier circuit 19 is applied to the LM drive circuit 15, and the linear motor 24 is driven toward a desired track. When the linear motor 24 is driven, the track cross signal obtained by binarizing TE is counted to calculate the moving distance, and the width of the track cross signal is measured to calculate the moving speed at that time. The reference speed obtained from the speed profile table 18 is switched according to the distance to the target address, that is, the number of remaining tracks to accelerate or decelerate. When the number of remaining tracks becomes 0, the applied acceleration (deceleration) signal is set to 0 and the tracking control is turned on.

After the tracking control is turned on, the address of the arrived track is confirmed and compared with the target address. When the confirmation address matches the target address (when the number of remaining tracks is 0), the search is completed. If the confirmation address does not match the target address, the difference between the target address and the track currently scanned by the light beam is obtained, the tracking control is turned off again, and the linear motor 24 is driven toward the desired track. The address is confirmed again in the arrival track and compared with the target address. When the confirmed address matches the target address (when the number of remaining tracks is 0), the search is completed.

As described above, the conventional search control device retries the movement until the track address after the movement of the light beam matches the target track address, and searches for the desired track.

[0012]

However, in such a conventional example, the tracking control element 23 and the linear motor 2 are changed due to a change with time or a change in temperature of the device.
4 changes, and the drive sensitivity or resonance level drifts.

The drift of the driving sensitivity deteriorates the ability to follow the reference speed and makes the search unstable with respect to a disturbance such as a vibration shock.

The drift of the resonance level deviates from the filter characteristic that traps the resonance value, and the resonance level in the control loop increases, so that the system becomes unstable.
In the worst case, the oscillation of the speed control system or the oscillation of the tracking control system after pulling in was generated. In such a state, the search becomes extremely unstable in any case, and it takes time to search, and in the worst case, the target track cannot be reached.

FIG. 18 shows the movement of the light beam during the search in the steady state (a), for example, the state where the driving sensitivity is increased at high temperature (b) and the state where the resonance value is increased (c).
It is shown in the waveform diagram of.

When the driving sensitivity varies as shown in FIG. 18B, the reference speed is set before the settling is performed following the speed profile for setting the reference speed of the speed control, as compared with the steady state (a). The tracking control is switched on, and the tracking control is turned on in the state in which the speed is varied at the time of pulling in. In such a state, even if the tracking control is turned on, the tracking cannot be pulled in,
The light beam causes a so-called slip, which goes too far over a desired track by a unit of hundreds to thousands. In order to search for a desired track, a retry is executed in this state as well, but there is a high possibility that slip will occur during the retry, and the number of retries increases and the search time becomes long.

When the resonance value increases as shown in FIG. 18 (c), the impact at the time of retraction triggers and the tracking control system oscillates. In the worst case, the oscillation deviates from the tracking and the retry is performed. Therefore, the search time was long, as was the case when the driving sensitivity varied.

When vibration shock is applied during the search,
Even when the amount of eccentricity of the disk is extremely large, the speed fluctuation of the moving speed of the light beam increases, the pulling in becomes unstable in the same manner, the number of retries increases, and the search time is long.

The present invention has been made in view of the above technical problems, and stabilizes the speed control during the search even when the drive sensitivity or the resonance level drifts due to a change with time or a change in temperature, and the pull-in speed. Provides a highly reliable search control device that secures pull-in performance by reducing fluctuations in vibration, and that can perform stable search even for disturbances such as vibration and shock, and for disks with large eccentricity. The purpose is to do.

[0020]

In order to achieve the above object, the present invention is configured as follows.

That is, the search control device of the present invention according to claim 1 is a converging means for converging and irradiating the recording medium with the light beam, and a moving means for moving the light beam converged by the converging means. Track deviation detecting means for generating a signal according to the positional relationship between the optical beam and the track of the recording medium by the transmitted light transmitted through the recording medium or the reflected light reflected by the recording medium, Tracking control means for driving the moving means in response to a signal from the track deviation detection means to control the light beam to scan over the track, and a light beam crossing a plurality of tracks to a desired track. Speed control means for controlling the moving speed when moving toward a predetermined speed profile, and the speed control means with the predetermined speed profile as a reference. Error detection means for detecting an error between the arriving track and the desired track after moving once, and the predetermined speed serving as a reference for control by the speed control means according to the error detected by the error detection means. Speed switching means for switching the profile.

According to another aspect of the present invention, there is provided a search control device,
Converging means for converging and irradiating the recording medium with the optical beam, moving means for moving the converging optical beam by the converging means, and transmitted light transmitted by the optical beam on the recording medium or the recording medium. The track deviation detecting means for generating a signal corresponding to the positional relationship between the optical beam of the recording medium and the track by the reflected light reflected by the recording medium, and the moving means driven in response to the signal of the track deviation detecting means Tracking control means for controlling the beam to scan over a track, and the moving speed when the light beam moves toward a desired track across a plurality of tracks, based on a predetermined speed profile. Speed control means for controlling, and movement for counting the number of movements until the light beam reaches a desired track by the speed control means on the basis of the predetermined speed profile. The number detecting means, depending on the number of movements detected by said moving count detection means, and a speed switching means for switching said predetermined speed profile as a reference for control by the speed control means.

The search control device of the present invention according to claim 3 is
Converging means for converging and irradiating the recording medium with the optical beam, moving means for moving the converging optical beam by the converging means, and transmitted light transmitted by the optical beam on the recording medium or the recording medium. The track deviation detecting means for generating a signal corresponding to the positional relationship between the optical beam of the recording medium and the track by the reflected light reflected by the recording medium, and the moving means driven in response to the signal of the track deviation detecting means Tracking control means for controlling the beam to scan over a track, and the moving speed when the light beam moves toward a desired track across a plurality of tracks, based on a predetermined speed profile. The speed control means for controlling, the temperature detecting means for detecting the temperature in the device, and the predetermined speed as a reference for the control by the speed controlling means according to the detection output of the temperature detecting means. And a speed switching means for switching the profile.

A search control device according to a fourth aspect of the present invention is
Converging means for converging and irradiating the recording medium with the optical beam, moving means for moving the converging optical beam by the converging means, and transmitted light transmitted by the optical beam on the recording medium or the recording medium. The track deviation detecting means for generating a signal corresponding to the positional relationship between the optical beam of the recording medium and the track by the reflected light reflected by the recording medium, and the moving means driven in response to the signal of the track deviation detecting means Tracking control means for controlling the beam to scan over a track, and the moving speed when the light beam moves toward a desired track across a plurality of tracks, based on a predetermined speed profile. Speed control means for controlling, acceleration detection means for detecting vibration or impact applied to the device, and control by the speed control means according to the detection output of the acceleration detection means And a speed switching means for switching said predetermined speed profile as a reference.

The retrieval control device of the present invention according to claim 5 is
Converging means for converging and irradiating the recording medium with the optical beam, moving means for moving the converging optical beam by the converging means, and transmitted light transmitted by the optical beam on the recording medium or the recording medium. The track deviation detecting means for generating a signal corresponding to the positional relationship between the optical beam of the recording medium and the track by the reflected light reflected by the recording medium, and the moving means driven in response to the signal of the track deviation detecting means Tracking control means for controlling the beam to scan over a track, and the moving speed when the light beam moves toward a desired track across a plurality of tracks, based on a predetermined speed profile. Speed control means for controlling, eccentricity detection means for detecting the eccentricity amount of the recording medium based on the signal of the track deviation detection means, and the speed control according to the detection output of the eccentricity detection means. And a speed switching means for switching said predetermined speed profile as a reference of control by means.

According to a sixth aspect of the present invention, there is provided a search control device,
Converging means for converging and irradiating the recording medium with the optical beam, moving means for moving the converging optical beam by the converging means, and transmitted light transmitted by the optical beam on the recording medium or the recording medium. The track deviation detecting means for generating a signal corresponding to the positional relationship between the optical beam of the recording medium and the track by the reflected light reflected by the recording medium, and the moving means driven in response to the signal of the track deviation detecting means Tracking control means for controlling the beam to scan over a track, and the moving speed when the light beam moves toward a desired track across a plurality of tracks, based on a predetermined speed profile. A pull-in state for detecting the pull-in state of the tracking control means after the movement based on the signal of the speed control means for controlling and the track deviation detecting means immediately after the movement of the light beam It means out, in accordance with the detection output of the retraction state detecting means, and a speed switching means for switching said predetermined speed profile as a reference for control by the speed control means.

According to a seventh aspect of the present invention, there is provided a search control device,
The structure according to any one of claims 1 to 6, wherein the speed control means uses a speed control signal which is a difference signal between a speed reference signal based on the predetermined speed profile and an actual moving speed of the light beam. The moving speed is controlled, and the speed switching means switches the speed profile by changing the gain of the speed reference signal.

The search control device of the present invention according to claim 8 is:
The structure according to any one of claims 1 to 6, wherein the speed control means uses a speed control signal which is a difference signal between a speed reference signal based on the predetermined speed profile and an actual moving speed of the light beam. The moving speed is controlled by the speed switching means, and the speed profile is switched by changing the gain of the speed control signal.

[0029]

According to the search control device of the present invention, the moving speed of the light beam is controlled on the basis of a predetermined speed profile to move the light beam toward a desired track,
The error between the arrival track and the desired track is detected, and depending on the error, for example, if the error is large, it is considered that the search is unstable, and when moving to the next desired track, the velocity profile is detected. By controlling the moving speed by suppressing the moving speed, it is possible to secure the stability of the speed control and the pull-in associated therewith, and to reliably search for a desired track. On the other hand, if the usage environment improves due to changes in ambient temperature, etc., and the search can be performed sufficiently stably due to a small error between the arriving track and the desired track in multiple searches, the speed profile is By switching and increasing the moving speed, it is possible to perform stable and high-speed search.

According to the search control device of the present invention as defined in claim 2, the number of movements (the number of retries) until the light beam whose movement speed is controlled on the basis of a predetermined velocity profile reaches a desired track is determined. Depending on the number of movements detected, for example, when the number of movements is large, it is determined that the search is unstable, and when moving to the next desired track,
By switching the speed profile and suppressing the moving speed, it is possible to ensure the stability of the speed control and the pull-in associated therewith, and to reliably search for a desired track. On the contrary, if the environment is improved due to changes in the ambient temperature and the number of searches to reach the desired track is small and the search can be performed sufficiently stably in a large number of searches, the speed profile is switched. By increasing the moving speed with the search, it is possible to perform a stable and high-speed search.

According to the search control device of the present invention as set forth in claim 3, depending on the temperature detected by the temperature detecting means, for example, when the detected temperature is equal to or higher than a predetermined temperature (lower than a predetermined temperature),
It is estimated that the search becomes unstable due to the characteristics of the tracking control element and the linear motor changing, and the speed profile is switched to suppress the moving speed, ensuring the stability of speed control and the accompanying pull-in, and ensure the desired. It becomes possible to search to the track. On the contrary, when the environment for use is improved due to the change in ambient temperature, the speed profile is switched to increase the moving speed, so that the search can be performed stably and at high speed.

According to the search control device of the present invention as set forth in claim 4, depending on the detection output of the acceleration detecting means, for example, when the detected acceleration is a predetermined value or more, the search control device is vibrated or shocked. Even if a disturbance such as is applied, the speed profile is switched to suppress the moving speed, ensuring stability of speed control and accompanying retraction even during vibration or impact, and reliably search for the desired track. It becomes possible to do. On the contrary, when the vibration or shock disappears, the speed profile is switched to increase the moving speed, so that stable and high-speed search can be performed.

According to the search control device of the present invention as defined in claim 5, the eccentricity detecting means detects the eccentricity amount of the disk as the recording medium on the basis of the track deviation signal which is the signal of the track deviation detecting means, and the eccentricity is detected. Depending on the quantity, for example,
When the amount of eccentricity is large, the speed profile is switched to suppress the moving speed, so that speed control and accompanying pull-in stability can be ensured even for a disk with a large amount of eccentricity, and a desired track can be reliably searched. It becomes possible.

According to the sixth aspect of the search control device of the present invention, the pull-in state detecting means detects the pull-in state of the tracking control system, that is, the slippage or the oscillation state based on the track deviation signal immediately after the search is completed. By switching the speed profile and suppressing the moving speed according to the state, it is possible to always ensure the stability of the speed control and the pull-in associated therewith, and to reliably search for a desired track. On the other hand, when the environment for use is improved due to changes in ambient temperature or the like and the pull-in state is good in a large number of searches, the speed profile is switched to increase the moving speed to perform a stable and high-speed search. It becomes possible.

According to the search control device of the present invention as defined in claim 7, the speed profile is switched by changing the gain of the speed reference signal based on a predetermined speed profile, so one kind of speed profile is stored in the memory. You only have to save the memory capacity.

According to the search control device of the present invention as defined in claim 8, the gain of the speed control signal, which is a difference signal between the speed reference signal based on a predetermined speed profile and the actual moving speed, is varied, Since the profiles are switched, only one kind of speed profile needs to be stored in the memory, and the memory capacity can be reduced.

[0037]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of the search control apparatus according to the first embodiment of the present invention. The portions corresponding to the conventional example in FIG. Omit it.

The reflected light of the light beam 6 from the disk 7 is
Polarization beam is transmitted through the converging lens 5 and the rising mirror 4.
The light passes through the optical splitter 3 and is input to the photodetector 8 having a two-divided structure. The outputs a and b of the photodetector 8 are preamplifier 9 respectively.
After being amplified by a and 9b, it is input to the differential amplifier 10 constituting the track deviation detecting means, and a track deviation signal (hereinafter referred to as "TE") can be obtained from the output of the differential amplifier 10. TE is an AD converter 33 and an AD converter 42 with a built-in digital signal processor (DSP) 40.
And to the binarization circuit 16. This DSP40
It has functions as a tracking control means, a speed control means for controlling the moving speed of the light beam based on the speed profile, an error detection means for detecting the number of track errors at the time of search, and a speed switching means for switching the speed profile.

The outputs of the preamplifiers 9a and 9b are input to the summing amplifier 31. Output TS of summing amplifier 31
Is a signal corresponding to the amount of total reflected light from the disk 7, and therefore the track address on the disk 7 can be read by processing this signal by the address reading circuit 32. The output of the address reading circuit 32 is input to the arithmetic processing unit 41, which is the core of the DSP 40, and the track address where the light beam is located can be detected.

The TE input to the AD converter 42 is input to the phase compensation filter 43. Phase compensation filter 43
Is a digital filter composed of an adder, a multiplier and a delay device. The output of the phase compensation filter 43 is passed through a digitally configured switch 44 and a DA converter 45.
Is converted into an analog signal and input to the TR drive circuit 22, where the power is amplified and the level is converted. The tracking control element 23 is driven by the output signal of the TR drive circuit 22, and the tracking control element 23 is driven so that the converging lens 5 is moved in the radial direction of the disk 7 based on TE so that the light beam scans the track. Tracking control is performed.

TE is also input to the AD converter 33, and after being converted into a digital signal, it passes through a low-pass filter 34 that limits the frequency band and removes noise,
Phase compensation filter 3 for compensating the phase of the linear motor 24
It is entered in 5. The low-pass filter 34 and the phase compensation filter 35 are digital filters realized by arithmetic processing, like the phase compensation filter 43. The output of the phase compensation filter 35 is converted into an analog signal by the DA converter 37 via the switch 36 that switches the drive of the linear motor 24 during tracking control and search, and the LM
It is input to the drive circuit 15 and power is amplified. The linear motor 24 is driven by the output of the LM drive circuit 15 so that the center of the light beam and the center of the converging lens 5 coincide with each other when the optical beam on the disk 7 scans the track. That is, the disc 7 is driven so that the optical axis of the light beam converged and irradiated is perpendicular to the disc, and the transfer control is realized.

At the start of the search, the target address of the desired track is input to the arithmetic processing unit 41, and the address of the track where the light beam is currently located is recognized from the signal obtained from the address reading circuit 32. The moving distance (number of moving tracks) is calculated from the difference between the current address and the target address.

The speed profile tables A (47a), B (47b), and C (47) are stored on the ROM of the DSP 40.
c) and D (47d) are stored, and the reference speed corresponding to the distance has a relationship of A ≧ B ≧ C ≧ D as shown in FIG. 2 (a) is full stroke, FIG. 2 (b)
Shows the velocity profile in the case of 1/2 stroke.

In the initial state, the speed profile table A is selected by the arithmetic processing unit 41 and the multiplexer 46, and the mode in which the search time is the fastest is set. Actually, the argument from the speed profile tables 47a to 47d is an acceleration output in which the final speed is the reference speed, and the acceleration signal is switched so as to become the optimum speed according to the number of remaining tracks after the start of movement. With reference speed (V
ref) is changed, and acceleration / deceleration is performed so as to follow the reference speed.

Since the light beam traverses one track and a TE output having a sinusoidal waveform of one cycle appears, the number of light beams moved can be obtained by counting the output pulses of the binarization circuit 16. The absolute position during movement can be detected by adding to the address detected before the movement. Also, when the moving speed of the light beam becomes faster, the sine wave TE obtained when crossing the track becomes denser (higher frequency), and when the moving speed becomes slower, the TE sinusoidal wave obtained when crossing the track becomes coarse (lower frequency). Become. Therefore, the moving speed of the light beam can be obtained as the current moving speed (Vreal) by measuring the output pulse width (or pulse interval) of the binarization circuit 16. The differential amplification section 48 uses the reference speed Vref and the moving speed Vreal.
Difference signal (speed control signal) is generated, and this difference signal is input to the LM drive circuit 15 via the switch 36 and the DA converter 37. Therefore, during the search, the linear motor 24 is driven based on this difference signal, and the linear motor 24 is controlled to follow the reference speed according to the speed profile, that is, the distance (the number of tracks) set in the speed profile table on the ROM of the DSP 40. Will move.

FIG. 3 is a flowchart showing the search algorithm of the first embodiment. The algorithm will be described below with reference to FIGS. 1 to 3.

When a read / write or search command is issued from the host computer, the arithmetic processing unit 41 of the DSP 40 selects the set speed profile (initially A) (S1). Then, the tracking control is turned off (S2), the reference speed at that time is calculated from the number of moving tracks based on the set speed profile table A (S3), and the number of remaining tracks is counted while counting the signal of the binarization circuit 16. The reference speed is switched accordingly. During the movement, the width of the signal of the binarization circuit 16 is measured to calculate the actual movement speed, and the linear motor 24 is accelerated by driving the linear motor 24 with the difference signal so that the calculated movement speed and the reference speed match. After that, the vehicle decelerates and converges to the pulling speed (constant) in front of the target track (S4 to S).
7).

When the pull-in speed becomes constant and the counter value becomes 0, tracking is pulled in (S8), and the address of the reached track is read by the address reading circuit 32.
It is further detected (S9) and compared with the target address of the desired track initially set (S10). When the target track and the arrival track match, the search is completed (S14).

In the first embodiment, when the number of error tracks from the target track is less than a predetermined value (50), the reference speed corresponding to the remaining number is set again according to the speed profile table A, and the linear motor 24 To retry to the desired track. If the number of errors from the target track is a predetermined value (for example, 50) or more, the speed profile table 47 is switched from A to B (S12, S1).
3) According to the speed profile table B, the reference speed corresponding to the remaining number is set, and the linear motor 24 is retried toward the desired track.

After the retry, the address of the arrived track is detected (S9), and the number of error tracks from the target address is confirmed (S11). Similar to the first time, when the target track and the arriving track match, the search is completed (S1
1, S14). When the number of error tracks with respect to the target track is within a predetermined value (for example, 50), the reference speed corresponding to the remaining number is set again according to the previous speed profile table A or B, and the linear motor 24 is set to a desired track. To try again. When the number of errors with respect to the target track is equal to or more than a predetermined value (for example, 50), the speed profile table 47 is further delayed than the previous time, that is, when the previous time A is B, the previous time B is C, and A reference speed corresponding to the remaining number is set according to the speed profile table B or C, and the linear motor 24 is retried toward a desired track (S12, S1).
3).

As described above, the retry is repeated until the target address and the arrival address match, that is, the remaining number becomes zero.

At this time, if the number of remaining lines after the retry exceeds a predetermined value, it is estimated that the search is unstable, and the speed profile table is switched from A to B, C, D to suppress the reference speed and control the speed. Improve the tracking performance of the system and try again. This makes it possible to search more stably during retries, reliably reach the target track, and shorten the search time because the number of retries can be reduced.

If the speed profile table is switched from A to C when the search from track X to track Y is completed, then track Y to track Z is selected.
When searching for, the initial speed profile table is set to C, and the speed profile table is switched from C to D according to the number of errors.

As another embodiment of the present invention, the initial velocity profile table may always start from "A".

The number of speed profile tables is D
An appropriate number may be set according to the ROM capacity of SP40.

It is also assumed that the operating environment of the drive may be improved due to changes in ambient temperature.
When the number of errors is always less than or equal to a predetermined value (50) in zero movement (search), the search time is shortened from D to C, C to B, and B to A with the speed profile reversed. If it is configured to switch to, it is possible to always use the device in an optimal state, and it is possible to sufficiently bring out the performance.

Next, the second embodiment will be described. FIG. 4 is a block diagram showing the configuration of the search control device according to the second embodiment of the present invention. The parts corresponding to those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted. .

The second embodiment can be realized by changing the processing in the arithmetic processing section 41 in the same structure as that of FIG. 1 showing the structure of the first embodiment. That is, in the second embodiment, the arithmetic processing unit 41 is provided with the retry counter 41a for counting the number of retries, and the initial speed profile is switched according to the count value. Similar to the speed profile tables 47a to 47d in FIG. 1, the speed profile tables 47a to 47d in FIG. 4 are stored in the ROM of the DSP 40 with the speed profile tables shown in FIG. . Therefore, description of the configuration shown in FIG. 4 is omitted.

FIG. 5 is a flow chart showing the search algorithm of the second embodiment, and the parts corresponding to the steps in FIG. 3 are given the same numbers. 4 and 5
The algorithm will be described below with reference to.

When a read / write or search command is issued from the host computer, the arithmetic processing unit 41 of the DSP 40 selects the set speed profile (initially A) (S1). Then, the tracking control is turned off (S2), the reference speed at that time is calculated from the number of moving tracks based on the set speed profile table A (S3), and the number of remaining tracks is counted while counting the signal of the binarization circuit 16. The reference speed is switched accordingly. While moving, the width of the signal of the binarization circuit 16 is measured to calculate the actual moving speed, and the linear motor 24 is driven by the difference signal so that the calculated moving speed and the reference speed match, thereby accelerating. After that, the vehicle decelerates and converges to the pulling speed (constant) in front of the target track (S4 to S).
7).

When the pull-in speed becomes constant and the counter value becomes 0, tracking is pulled in (S8), the address of the reached track is detected by the address reading circuit 32 (S9), and the desired track initially set is set. (S10). When the target track and the arrival track match, it is judged whether or not the number of retries until reaching the target track is a predetermined value, for example, less than 5 times (S15), and when it is less than 5, it is searched. Is stable, the search is completed as it is (S14). When the number of retries is 5 or more, it is estimated that the search is unstable, and when the next desired track is searched, the initial speed profile is changed from the currently set initial speed profile. To suppress B, for example, A to B, or B
To C or C to D to suppress the reference speed, thereby improving the tracking performance of the speed control system and driving the linear motor 24.

If the target track and the arrival track do not match, the procedure is the same as in the first embodiment. That is, when the number of error tracks with respect to the target track is less than or equal to a predetermined value (50), the reference speed corresponding to the remaining number is set again according to the initial speed profile table A, and the linear motor 2
Retry 4 toward the desired track. If the number of errors from the target track is a predetermined value (for example, 50) or more, the speed profile table 47 is switched from A to B (S12, S13), and the speed profile table B
Then, the reference speed corresponding to the remaining number is set, and the linear motor 24 is retried toward a desired track.

As described above, similarly to the first embodiment, the movement is repeated toward the desired track, and the retry is performed until the target address and the arrival address match, that is, the remaining number becomes 0. The arithmetic processing unit 40 counts the total number of retries, and when the number of retries is 5 or more, it is estimated that the search is unstable, and when the next desired track is searched, the initial speed profile is calculated. By switching and suppressing the reference speed, the tracking performance of the speed control system is improved and the linear motor 24 is driven.

When the next desired track is searched, the number of retries is counted in the same manner, and when the number of retries becomes 5 times or more again, the initial speed profile is changed from B to C or again at the next search. , C to D and further suppress the reference speed to improve the tracking performance of the speed control system to drive the linear motor 24.

By repeating this process, the search is repeated so that the speed profile converges to an appropriate speed profile and the target track can be surely reached. Also, the search time can be shortened because the number of retries decreases when the speed profile is optimized.

It is also assumed that the drive usage environment may be improved due to changes in ambient temperature.
When the number of retries is always less than the predetermined value (5 times) in the movement (search), the speed profile is switched to D to C, C to B, and B to A in the direction in which the search time becomes faster. With this configuration, the device can always be used in an optimum state, and the performance can be sufficiently obtained.

As another embodiment of the present invention, without switching the speed profile depending on the number of errors,
Alternatively, only the initial speed profile may be switched depending on the number of retries.

Next, the third embodiment will be described. Figure 6
FIG. 6 is a block diagram showing a configuration of a search control device according to a third embodiment of the present invention, and portions corresponding to those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

In the third embodiment, the linear motor 2
4. A temperature sensor 51 for detecting the temperature inside the device is mounted on the frame of the device equipped with the tracking control element 23 and the like.
Is fixed, and is input to the arithmetic processing unit 41 in the DSP 40 via the amplifier 52 and the AD converter 53.
As a result, the DSP 40 can detect the temperature particularly near the linear motor 24 and the tracking control element 23.

As described in the problem to be solved by the invention, when the temperature inside the apparatus rises or falls, the moving speed of the light beam being searched for varies due to the variation of the resonance frequency and the resonance value of the tracking control element 23. In addition, since the lens shakes after the drawing, the error from the desired track increases.

Therefore, in the third embodiment, the speed profile is switched according to the temperature detected by the temperature sensor 51.

FIG. 7 shows an example of the temperature detected by the temperature sensor 51, the maximum speed of search at that time, and the speed profile to be set. As shown in FIG. ), The velocity profile is changed from A to B, B every time the temperature drift exceeds a predetermined range.
To C and C to D, the reference speed is set by a speed profile that stabilizes the speed control, and driving is performed at the suppressed speed. Therefore, by driving the linear motor 24 at a low speed, the induction of resonance due to rapid acceleration and rapid deceleration is eliminated, and even if resonance occurs, sufficient response time is improved by ensuring sufficient follow-up time to speed control disturbance. Therefore, it becomes possible to stably pull in the target truck.

Further, the speed becomes unstable due to variations in sensitivity of the linear motor 24 and the tracking control element 23 due to temperature changes, which makes the search unstable. Therefore,
When the sensitivity change due to temperature is large, the switching temperature of the speed profiles 47a to 47d may be set to a temperature exceeding the allowable range of sensitivity change.

As another embodiment of the present invention, within a predetermined temperature range corresponding to the speed profile A shown in FIG. 7, the speed profile is switched according to the number of errors similarly to the first embodiment. When the temperature is out of the predetermined temperature range, the speed profile shown in FIG. 7 may be preferentially switched.

Next, a fourth embodiment will be described. FIG.
FIG. 7 is a block diagram showing a configuration of a search control device according to a fourth embodiment of the present invention, and a portion corresponding to the first embodiment is
The same reference numerals are given and the description thereof is omitted.

In the fourth embodiment, the linear motor 2
4. An acceleration sensor 61 for detecting vibrations, impacts, etc. applied to the device is fixed to a frame 25 of the device on which a disc motor or the like (not shown) is mounted. The output of the acceleration sensor 61 is It is input to the arithmetic processing unit 63 in the DSP 40 via the low-pass filter 62 that reduces high-frequency noise and the AD converter 63. Thereby, the DSP 40 can detect the acceleration particularly in the direction perpendicular to the track (tracking direction). In the fourth embodiment, the speed profile is switched according to the magnitude of vibration, impact or the like.

FIG. 9 is a characteristic diagram showing an example of the relationship between the vibration acceleration applied to the device and the velocity profile set at that time. As shown in FIG. 9, when vibration or shock is applied to the device during the execution of the search, the speed profile is switched from A to B, B to C, and C to D according to the magnitude of the acceleration signal, and the speed is changed. A reference speed is set according to a speed profile that stabilizes the control, and driving is performed at a suppressed speed. Therefore, when a large vibration is applied, the speed control band is set low. This allows the linear motor 2
4 is driven at a low speed, and the response time is improved by ensuring a follow-up time for disturbance such as vibration impact, and it is possible to stably pull in the target track.

As another embodiment of the present invention, when there is no impact or vibration, that is, when the detected acceleration is less than a predetermined value, the speed profile is switched according to the number of errors as in the first embodiment. However, when a predetermined value is exceeded due to shock or vibration, the speed profile shown in FIG. 9 may be switched according to the detected acceleration.

Next, a fifth embodiment will be described. FIG.
Reference numeral 0 is a block diagram showing the configuration of the search control device according to the fifth embodiment of the present invention. Parts corresponding to those in the first embodiment are:
The same reference numerals are given and the description thereof is omitted.

When the focus control is turned on and the tracking control is turned off at the time of starting the apparatus, as shown in FIG. 11, TE has a sinusoidal signal whose number changes according to the eccentricity of the disk 7. Occurs. Therefore, the amount of eccentricity can be calculated by counting the number of TEs or 0 cross points for one rotation time.

By the way, the eccentricity of the disk 7 causes a speed fluctuation of the moving speed of the light beam during the search. Especially, in the pulling speed settling period immediately before the pulling, the moving speed of the light beam is about 5 mm / s, which is extremely low. Therefore, the influence of the eccentricity becomes large, failing in the pulling, and slipping away from the desired track.

Therefore, in this embodiment, when the apparatus is started up, the eccentricity counter 71 counts the binarized signal of TE which appears due to the eccentricity of the disk when the focus control is ON, and the eccentricity amount of the mounted disk is calculated. measure. Then, when the tracking control and the still are turned on and the desired track is searched, the speed profile is switched to A to D according to the eccentricity of the disk measured in advance as shown in FIG. It moves following the reference speed.

FIG. 12 is a characteristic diagram showing an example of the relationship between the amount of eccentricity of the mounted disk and the speed profile table to be selected. As shown in FIG. 12, when the disk eccentricity is less than 16 μm, the fastest table A, 16
Table B is selected when less than 32 μm and less than 32 μm, table C is selected when less than 32 μm and less than 48 μm, and table D is selected when greater than 48 μm. Therefore, when there is a large amount of eccentricity, a speed profile that allows stable speed control that does not affect the amount of eccentricity is selected, and the reference speed is set by that speed profile to drive at a suppressed speed. Therefore, by ensuring the follow-up time for the eccentricity, it is possible to improve the responsiveness and stably pull in the target track.

As another embodiment of the present invention, when the amount of eccentricity is within the range corresponding to the speed profile A in FIG. 12, the speed is changed according to the number of errors as in the first embodiment. The profile may be switched, and when the amount of eccentricity deviates from the range corresponding to the speed profile A in FIG. 12, the speed profile in FIG. 12 may be preferentially switched.

Next, a sixth embodiment will be described. FIG.
FIG. 3 is a block diagram showing the configuration of the search control device according to the sixth embodiment of the present invention. The parts corresponding to those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

In the initial state of the apparatus, the speed profile 47 is set to A, which is the highest speed, in order to obtain the maximum performance.

However, when the resonance frequency of the tracking control element 23 deviates due to the temperature change and the change over time and the resonance value increases, even if the tracking control is turned on and the target address is reached, the target slips away from the target address. Alternatively, oscillation occurs after the tracking control is turned on, the oscillation component increases, and the tracking control deviates. Therefore, the number of retries increases and the search time increases. A TE waveform diagram showing this state is shown in FIG.

After the light beam reaches the target address and the tracking control is turned on, TE for a predetermined period T is sampled. When the slip shown in FIG. 14 (a) and the oscillation shown in FIG. 14 (b) occur, the amplitude of TE in the period T becomes large, so that the average value or the maximum value (minimum value) is used. The state after pulling in can be estimated. Therefore, in the sixth embodiment, the speed profile described above is switched according to the magnitude of the estimated value (for example, the average value of the TE amplitude after pulling in), and the linear motor 24 is driven at the suppressed speed to perform the search. It is possible to secure stability and repeatably pull into the target track.

It is also assumed that the operating environment of the drive may be improved due to changes in the ambient temperature.
When the amplitude value of TE after the pull-in is less than the predetermined value during the movement (search) of times, the speed profile is switched to the direction from D to C, C to B, and B to A in the direction in which the search time becomes faster. With this configuration, the device can always be used in an optimum state, and the performance can be sufficiently obtained.

In the first to sixth embodiments, the configuration having a plurality of speed profiles and switching the profiles according to conditions has been described.
Even if it does not have a plurality of profiles, if one speed profile is used to switch the gain of the output stage, the same effect can be obtained.
It is possible to reduce the ROM capacity of P40.

This structure will be described with reference to FIG. FIG. 15 is an example in which the first embodiment is applied to a configuration for switching speed profiles, and is a block diagram showing each configuration. This will be described below with reference to FIG. In addition,
The parts corresponding to those in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted.

Unlike FIG. 1, only one kind of speed profile table 47 is stored in the ROM of the DSP 40, and this one kind of speed profile table is converted into an appropriate gain by the gain switching unit 91 composed of a multiplier. By doing so, the reference speed corresponding to the distance can be switched as shown in FIG.

As shown in FIG. 16, the gain switching unit 91
The reference speed that is set by increasing the gain of (the coefficient of the multiplier is increased) is relatively increased, and is set by decreasing the gain of the gain switching unit 91 (the coefficient of the multiplier is decreased). The reference speed is relatively small. In the initial state when the normal drive is activated, the gain switching unit 91 is set to the maximum value, which is the mode in which the search time is the fastest.

Similar to the first embodiment, the number of error tracks between the target address and the reaching address in one movement when searching for a desired track is obtained, and the gain is used instead of switching the speed profile table according to the error. The gain of the switching unit 91 is switched.

That is, when a read / write or search command is issued from the host computer, D
The arithmetic processing unit 41 of SP40 selects a predetermined gain of the gain switching unit 91 that has been set. After that, the tracking control is turned off, the reference speed at that time is calculated from the number of moving tracks based on the speed profile table and its gain value, and while counting the signal of the binarization circuit 16, the reference speed is switched according to the remaining number. To go. While moving, the width of the signal of the binarization circuit 16 is measured to calculate the actual moving speed, and the linear motor 24 is driven by the difference signal so that the calculated moving speed and the reference speed match,
After accelerating, decelerate and converge to the pull-in speed (constant) before the target track.

When the pulling-in speed becomes constant and the counter value becomes 0, tracking is pulled in, the address of the reached track is detected by the address reading circuit 32, and it is compared with the target address of the initially set desired track. . When the target track and the arrival track match, the search is completed. When the number of error tracks with respect to the target track is less than a predetermined value (50), gain switching is not executed, the reference speed corresponding to the remaining number is set again according to the speed profile table 47, and the linear motor 24 is set to the desired track. To try again. When the number of errors from the target track is a predetermined value (for example, 50) or more, the gain is switched to an appropriate value, the reference speed corresponding to the remaining number is set according to the speed profile table at that time, and the linear motor 24 is desired. Try again for the truck.

After the retry, the address of the arrived track is detected, and the number of error tracks from the target address is confirmed. Similar to the first time, when the target track and the arriving track match, the search is completed. If the number of error tracks with respect to the target track is within a predetermined value (for example, 50), the linear motor 24 is retried toward the desired track without performing gain switching. When the number of errors from the target track is equal to or greater than a predetermined value (for example, 50), the gain is switched again and the linear motor 24 is retried toward the desired track.

As described above, the retry is repeated until the target address and the arrival address match, that is, the remaining number becomes zero. At that time, if the remaining number after the trial exceeds the predetermined value, it is estimated that the search is unstable and the gain is gradually decreased to suppress the reference speed and improve the tracking performance of the speed control system. Try again. Therefore, at the time of retry, the search can be performed more stably, the target track can be reliably reached, and the search time can be shortened because the number of retries can be reduced.

As in the case of the first embodiment, it is assumed that the environment in which the drive is used is improved due to changes in the ambient temperature and so on. Therefore, the number of errors is always below a predetermined value (50) in 100 movements (searches). In such a case, if the gain switching unit 91 is configured to switch in the direction in which the gain increases (direction in which the search time becomes faster), the device can always be used in an optimum state and the performance can be sufficiently obtained. Becomes

Since the output of the gain switching unit 91 is a signal for driving the linear motor 24, instead of switching the gain of the gain switching unit 91, the differential amplifying unit 48 is used.
Even if the gain switching unit 92 switches the output gain, the same effect can be obtained.

The gain switching structure described above can be replaced with a structure for switching the speed profile. That is, it can be applied to all of the above-described first to sixth embodiments.

Furthermore, as another embodiment of the present invention, the first
-By combining each of the sixth embodiments, a search with higher stability may be realized.

[0104]

As described above, according to the present invention, the speed profile is switched according to the number of errors between the arrival track after one movement in the search and the desired track, or the desired track is selected. The speed profile is switched according to the number of movements (retry times) until reaching, or the apparatus is equipped with temperature detecting means and acceleration detecting means and the speed profile is switched according to the detection output. Alternatively, the amount of eccentricity of the recording medium disk is detected, and the speed profile is switched according to the amount of eccentricity. Alternatively, after the tracking is pulled in at the end of the search, the pulling state, that is, oscillation or slippage is detected based on the track error signal, and the speed profile is switched according to the state, so that the change over time of the device Even if the tracking control element and linear motor characteristics change due to temperature changes and the drive sensitivity or resonance level drifts, the reference speed according to the distance is suppressed, speed control during search is stabilized, and pull-in speed fluctuations It is possible to secure the pull-in performance by reducing the noise, and it is possible to perform a stable search for disturbances such as vibration and shock, and even for disks with a large amount of eccentricity. It provides a high-performance and highly reliable device that enables search.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a search control device according to a first embodiment of the present invention.

FIG. 2 is a characteristic diagram showing characteristics of a velocity profile in the example.

FIG. 3 is a flowchart showing a search algorithm in the embodiment.

FIG. 4 is a block diagram showing a configuration of a search control device according to a second embodiment of the present invention.

FIG. 5 is a flowchart showing a search algorithm in the embodiment.

FIG. 6 is a block diagram showing a configuration of a search control device according to a third embodiment of the present invention.

FIG. 7 is a characteristic diagram showing a relationship between a temperature detected by a temperature sensor and a velocity profile set at that time in the same embodiment.

FIG. 8 is a block diagram showing a configuration of a search control device according to a fourth embodiment of the present invention.

FIG. 9 is a characteristic diagram showing the relationship between the acceleration detected by the acceleration sensor and the velocity profile set at that time in the embodiment.

FIG. 10 is a block diagram showing a configuration of a search control device according to a fifth embodiment of the present invention.

FIG. 11 is a waveform diagram showing TE and its binarized signal input to the eccentricity detection means in the embodiment.

FIG. 12 is a characteristic diagram showing the relationship between the amount of eccentricity detected by the eccentricity detecting means and the velocity profile set at that time in the embodiment.

FIG. 13 is a block diagram showing a configuration of a search control device according to a sixth embodiment of the present invention.

FIG. 14 is a waveform diagram showing a state of a track deviation signal detected by the pull-in detection unit in the embodiment.

FIG. 15 is a block diagram showing a configuration of a search control device in which the first exemplary embodiment of the present invention is realized by another configuration.

16 is a characteristic diagram showing characteristics of a velocity profile in the search control device of FIG.

FIG. 17 is a block diagram showing a configuration of a conventional search control device.

FIG. 18 is a waveform diagram of a moving speed and a track deviation signal for explaining the operation of the conventional search control device.

[Explanation of symbols]

 1 Semiconductor Laser (Light Source) 2 Coupling Lens 3 Deflection Beam Splitter 4 Startup Mirror 5 Converging Lens 6 Optical Beam 7 Disk 8 Photodetector 9 Collection Preamplifier 10 Differential Amplifier 11 Gain Switching Circuit 11 Optical Beam 12 Low-pass filter 13 Phase compensation filter 14 Switch 15 LM drive circuit 16 Binarization circuit 17 Arithmetic circuit 18 Speed table 19 Differential amplification circuit 20 Phase compensation filter 21 Switch 22 TR drive circuit 23 Tracking control element 24 Linear Motor 25 Device frame 31 Adder circuit 32 Address reading circuit 33 AD converter 34 Low pass filter 35 Phase compensation filter 36 Switch 37 DA converter 40 Digital signal processor 41 Arithmetic processing unit 42 AD converter 43 Phase compensation filter 44 Low Area Over filter 45 DA converter 46 Multiplexer 47 Speed table 48 Differential amplifier 51 Temperature sensor-52 Amplifier 53 AD converter 61 Acceleration sensor 62 Low-pass filter 63 AD converter 71 Eccentricity counter 81 Entrainment detection unit 91 Gain switching unit 92 Gain switching section

Claims (8)

[Claims] 1. A converging means for converging and irradiating a light beam onto a recording medium, a moving means for moving the light beam converged by the converging means, and the light beam transmitted through the recording medium. Track deviation detecting means for generating a signal according to the positional relationship between the optical beam of the recording medium and the track by transmitted light or reflected light reflected from the recording medium, and the moving means according to the signal of the track deviation detecting means. And a tracking control means for controlling the optical beam to scan over the tracks, and a moving speed when the light beam moves across a plurality of tracks toward a desired track. Speed control means for controlling on the basis of the speed profile,
Depending on the error detected by the error detection means, an error detection means for detecting an error between the arrival track and the desired track after the light beam has moved once by the speed control means on the basis of the predetermined speed profile. And a speed switching unit that switches the predetermined speed profile that serves as a reference for control by the speed control unit. 2. Converging means for converging and irradiating a recording medium with an optical beam, moving means for moving the converging optical beam by the converging means, and the optical beam transmitted through the recording medium. Track deviation detecting means for generating a signal according to the positional relationship between the optical beam of the recording medium and the track by transmitted light or reflected light reflected from the recording medium, and the moving means according to the signal of the track deviation detecting means. And a tracking control means for controlling the optical beam to scan over the tracks, and a moving speed when the light beam moves across a plurality of tracks toward a desired track. Speed control means for controlling on the basis of the speed profile,
Depending on the number of movements detecting means for counting the number of movements of the light beam until the light beam reaches a desired track by the speed control means on the basis of the predetermined velocity profile, and the number of movements detected by the number of movements detecting means, A search control device, comprising: speed switching means for switching the predetermined speed profile that serves as a reference for control by the speed control means. 3. A converging means for converging and irradiating a recording medium with an optical beam, a moving means for moving the converging optical beam by the converging means, and the optical beam transmitted through the recording medium. Track deviation detecting means for generating a signal according to the positional relationship between the optical beam of the recording medium and the track by transmitted light or reflected light reflected from the recording medium, and the moving means according to the signal of the track deviation detecting means. And a tracking control means for controlling the optical beam to scan over the tracks, and a moving speed when the light beam moves across a plurality of tracks toward a desired track. Speed control means for controlling on the basis of the speed profile,
A temperature detecting means for detecting a temperature in the apparatus; and a speed switching means for switching the predetermined speed profile serving as a reference for control by the speed controlling means according to a detection output of the temperature detecting means. Search control device. 4. A converging means for converging and irradiating a recording medium with an optical beam, a moving means for moving the converging optical beam by the converging means, and the optical beam transmitted through the recording medium. Track deviation detecting means for generating a signal according to the positional relationship between the optical beam of the recording medium and the track by transmitted light or reflected light reflected from the recording medium, and the moving means according to the signal of the track deviation detecting means. And a tracking control means for controlling the optical beam to scan over the tracks, and a moving speed when the light beam moves across a plurality of tracks toward a desired track. Speed control means for controlling on the basis of the speed profile,
An acceleration detecting means for detecting a vibration or an impact applied to the device, and a speed switching means for switching the predetermined speed profile as a reference for control by the speed controlling means according to a detection output of the acceleration detecting means. A search control device comprising. 5. Converging means for converging and irradiating a recording medium with a light beam, moving means for moving the converging light beam by the converging means, and the light beam transmitted through the recording medium. Track deviation detecting means for generating a signal according to the positional relationship between the optical beam of the recording medium and the track by transmitted light or reflected light reflected from the recording medium, and the moving means according to the signal of the track deviation detecting means. And a tracking control means for controlling the optical beam to scan over the tracks, and a moving speed when the light beam moves across a plurality of tracks toward a desired track. Speed control means for controlling on the basis of the speed profile,
An eccentricity detection unit that detects the amount of eccentricity of the recording medium based on the signal of the track deviation detection unit, and, in accordance with the detection output of the eccentricity detection unit, the predetermined speed profile serving as a reference for control by the speed control unit. A search control device comprising: speed switching means for switching. 6. A converging means for converging and irradiating a recording medium with an optical beam, a moving means for moving the converging optical beam by the converging means, and the optical beam transmitted through the recording medium. Track deviation detecting means for generating a signal according to the positional relationship between the optical beam of the recording medium and the track by transmitted light or reflected light reflected from the recording medium, and the moving means according to the signal of the track deviation detecting means. And a tracking control means for controlling the optical beam to scan over the tracks, and a moving speed when the light beam moves across a plurality of tracks toward a desired track. Speed control means for controlling on the basis of the speed profile,
The pull-in state detecting means for detecting the pull-in state of the tracking control means after the movement based on the signal of the track deviation detecting means immediately after the movement of the light beam, and the speed control according to the detection output of the pull-in state detecting means. A search control device comprising: speed switching means for switching the predetermined speed profile, which serves as a reference for control by the means. 7. The speed control means controls the moving speed of the light beam by a speed control signal which is a difference signal between a speed reference signal based on the predetermined speed profile and an actual moving speed of the light beam. 2. The speed switching means switches the speed profile by changing the gain of the speed reference signal.
7. The search control device according to any one of 6 to 6. 8. The speed control means controls the moving speed of the light beam by a speed control signal which is a difference signal between a speed reference signal based on the predetermined speed profile and an actual moving speed of the light beam. 2. The speed switching means switches the speed profile by changing the gain of the speed control signal.
7. The search control device according to any one of 6 to 6.