JP2002183982A - Access controller and optical disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an access error when a disturbance is added and to improve reliability. SOLUTION: The access controller has a speed control means for controlling the moving speed of a reading-out means for reading out the information recorded to a recording medium by controlling the drive signal to a drive means of the reading-out means. Further, the speed control means controls the moving speed of the reading-out means by switching over the speed pattern for outputting a target speed signal according to the drive signal to the drive means form a certain speed pattern to another speed pattern in accessing the desired track on the recording medium.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an access control device for a storage device using, for example, an optical disk or the like, and an optical disk device.

[0002]

2. Description of the Related Art In a storage device such as an optical disk device,
Various devices have been devised to reduce the access time while preventing access errors. Japanese Patent Application Laid-Open No. 6-28683 discloses an access test under a predetermined condition by a test means at the time of starting a storage device or the like as a measure against an access error when there is disturbance such as external vibration or power supply voltage drop. A technique for performing the above is disclosed.
In the access test, a test is performed to determine whether a normal access operation is performed. If an access error occurs during the test, the target value of the target speed of the linear motor that drives the optical head is switched. That is, when there is an abnormality, the setting of the target value of the target speed is switched, such as reducing the target speed.

[0003]

However, according to such a method, when an external force is not applied at the time of the test of the access operation and an external force is applied at the time of the actual access which is not at the time of the test,
The actual access operation sometimes ends in failure, and there is a problem in operation stability.

Conversely, if an external force is applied during the access operation test and the access fails, the target value is changed to a lower speed. Therefore, even when no disturbance is applied during the actual access operation, the target speed is reduced, so that in the actual access operation, the access time becomes longer and the performance is reduced.

[0005]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an access control device and an optical disk device that can prevent an access error from occurring without deteriorating performance.

The access control device of the present invention has a speed control means for controlling the moving speed of the reading means for reading the information recorded on the recording medium by controlling a driving signal to the driving means of the reading means. The speed control unit switches a speed pattern for outputting as a target speed signal from a certain speed pattern to another speed pattern in response to a drive signal to the drive unit when accessing a desired track on the recording medium, The moving speed of the reading means is controlled based on the other switched speed pattern.

Further, the access control device of the present invention switches the speed pattern when the magnitude of the drive signal reaches a level at which the value of the current flowing through the drive means is saturated.

Further, the optical disk device of the present invention controls the moving speed of the optical head by controlling the drive signal to the moving mechanism, and provides the moving mechanism with the moving mechanism when accessing a desired track on the optical disk. Target speed output means for switching a speed pattern for outputting as a target speed signal from a certain speed pattern to another speed pattern in accordance with the drive signal, and outputting a target speed signal. Based on the target speed signal from
The moving speed of the optical head is controlled by controlling a drive signal to a moving mechanism.

According to such a configuration, an access error can be prevented and the reliability can be improved while maximizing the performance.

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 to FIG. 4 show an embodiment of the present invention. FIG. 1 is a block diagram of a storage device according to an embodiment of the present invention. FIG. 2 is a block diagram of the speed control means in FIG. FIG. 3 is a diagram showing changes in a target speed signal and a drive signal of a linear motor which is one of the moving mechanisms when the storage device of FIG. 1 accesses a track. FIG. 4 is a diagram showing changes in the target speed signal and the drive signal of the linear motor when there is a disturbance or the like.

First, the overall configuration of the storage device will be described with reference to FIG.

In FIG. 1, reference numeral 1 denotes a spindle motor;
Is an optical disk. The optical disc 2 is rotated by the spindle motor 1. The light spot 3 is formed on the surface of the optical disc 2 by receiving the laser beam from the optical head 10. The optical head 10 includes a laser diode 6, a collimator lens 7, an objective lens 4, a beam splitter 8, and a tracking error detector 9. As a driving means, a tracking actuator 5 is attached to the objective lens 4, and a linear motor 11 is attached to the optical head 10.

In the optical head 10, the laser diode 6
Is applied to the disk 2 through the collimator lens 7 and the objective lens 4, and the reflected light is partially changed in the optical path by the beam splitter 8 and enters the tracking error detector 9. Based on the output signal of the tracking error detector 9, the operations of the tracking actuator 5 for adjusting the position of the objective lens 4 and the linear motor 11 for moving the entire optical head 10 are controlled as described later.

12 is a tracking error signal generating means,
13 is a phase compensating means at the time of tracking (track following), 14 is a speed control means, and 15 is a coupling compensating means at the time of tracking. Further, 16 and 17 are switch means. Reference numerals 18 and 19 are a driver for the tracking actuator and a driver for the linear motor, respectively. Reference numeral 20 denotes a control unit which includes a CPU and the like, and outputs a control signal, a timing signal, a selection signal and the like to the speed control means 14, the switch means 16 and 17, and the like.

The tracking error signal generating means 12
Upon receiving the analog output signal of the tracking error detector 9, the tracking error signal is supplied to the phase compensator 13 and the speed controller 14 at the subsequent stage. The output signal of the phase compensating means 13 for compensating for the servo system stabilization includes one of two inputs a of the switch 16 and the coupling compensating means 15.
Given to. The output signal of the coupling compensation means 15 is given to one of two inputs a of the switch 17. The two output signals of the speed control means 14 are applied to the other inputs b of the switches 16 and 17, respectively. Speed control means 1
The configuration of No. 4 will be described later. Switches 16 and 17
Are supplied to drivers 18 and 19, respectively. The output signal of the driver 18 is given to the tracking actuator 5. The output signal of the driver 19 is given to the linear motor 11. Switching of the switches 18 and 19, that is, whether the input is a or b is performed by a selection signal from the control unit 20. Although not shown here, the rotation of the spindle motor 1 is separately provided so that information recorded on the medium 2 can be correctly reproduced.
Controlled.

Next, the operation of the entire storage device will be described separately for the tracking mode and the access mode.

First, the operation in the reproduction / recording mode (tracking mode) will be described.

When information written on the surface track of the optical disk 2 rotated by the spindle motor 1 is reproduced or information is recorded on the surface track of the optical disk 2, the switches 16 and 17 are controlled by a selection signal from the control unit 20. The input is set to a side. When in the reproduction / recording mode, information on the recording medium is transmitted to the optical head 10.
And a part of the light beam is guided to the tracking error detector 9. The detection signal from the tracking error detector 9 is given to a tracking error signal generating means. Then, the tracking error signal from the tracking error signal generating means 12 is given to the phase compensating means 13, and the output signals of the phase compensating means 13 and the coupling compensating means 15 are sent to the drivers 18 and 19 via the switches 16 and 17, respectively. Given. The output signals (voltage values) of the drivers 18 and 19 control the linear motor 11 and the tracking actuator 5 as driving means, and control the position of the objective lens 4 so that the light spot 3 is located at the center of the track. . Thereby, the reproduction and recording of the information are appropriately performed.

Next, a speed control mode (access mode)
The operation at the time will be described.

When accessing a desired track on the recording medium, that is, when retrieving information on the disk, the inputs of the switches 16 and 17 are changed to b by a selection signal from the control unit 20 based on an access command. Side, and the speed control unit 14 controls the speed.
In the speed control mode, the drivers 18 and 19 supply output signals to the tracking actuator 5 and the linear motor 11 based on an output signal of a speed control unit 14 described later.

Next, the speed control means 14 will be described.
FIG. 2 is a block diagram of the speed control means 14.

Reference numeral 31 is a track counter, 32 is speed detection means, 34 is speed table switching means, and 35 is phase compensation means. Reference numeral 33 denotes speed table means, which includes a plurality of speed tables 1 and 2 and outputs a target speed signal corresponding to a speed pattern based on each speed table. 36 and 37 are amplification means, and 38 is a difference calculation means.

When in the speed control mode, information on the recording medium is read by the optical head 10 and a part of the light beam is guided to the tracking error detector 9. The output signal of the tracking error detector is provided to a tracking error signal generating means.

The tracking error signal from the tracking error signal generator 12 is input to the track counter 31 and the speed detector 32.

The track counter 31 counts the number of moving tracks at a predetermined timing under the control of the control unit 20. The number of moving tracks can be counted by extracting a transverse pulse from the tracking error signal. The number of remaining tracks is calculated based on the number of moving tracks, and the number of remaining tracks is calculated by the speed table means 3.
3 given. The speed table means 33 outputs a target speed signal corresponding to the input remaining number of tracks based on the speed pattern of the selected speed table. In addition,
Instead of the track counter 31 calculating and outputting the number of remaining tracks, the track counter 31 outputs the number of moving tracks counted and the remaining track number calculated by another circuit or the like is input to the speed table means 33, or Alternatively, the speed table means 33 may have a function of calculating the number of remaining tracks.

The speed table means 33 has a nonvolatile memory and stores a target speed value corresponding to the number of remaining tracks, and outputs a target speed signal when the number of remaining tracks is input. It is to be noted that a DSP (Digital Signal Pr) is not stored in a nonvolatile memory or the like.
The target speed signal may be output by performing a calculation each time by using a processor or the like.

The speed detecting means 32 calculates the moving speed of the optical head 10 as the reading means based on the tracking error signal and outputs a detected speed signal. Speed detection can be realized by various methods. For example, the crossing pulse of the track is extracted based on the tracking error signal, and the crossing pulse cycle is measured by counting the pulses for a predetermined period set by a timer or the like. The speed can be calculated based on the pulse count number corresponding to the cycle and output as a detected speed signal.

The difference between the target speed signal from the speed table means 33 and the detected speed signal from the speed detecting means 32 is calculated by a difference calculating means 38, and a signal corresponding to the difference value is given to the phase compensating means 35. Can be Phase compensation means 35
Are input to the amplifying means 36 and 37.
The amplifying unit 36 outputs a drive signal for the tracking actuator 5. The amplifying unit 37 outputs a drive signal of the linear motor 11. In this way, the moving speed of the optical head 10 as the information reading means is controlled.

The speed table switching means 34 monitors a drive signal of the linear motor 11. The two tables are switched based on the monitoring result, and after the switching, a speed pattern based on the switched speed table is output. This monitoring and switching function will be described later. In this case, the linear motor 11 saturates at a lower current value with respect to the output of the phase compensator 35 than the tracking actuator 5. Here, the monitoring and switching are performed based on the output signals of the amplifying units 36 and 37, but may be performed based on the output signals of the drivers 18 and 19.

Next, how the output of the target speed signal and the output of the linear motor drive signal in the speed table change with time will be described with reference to FIG. FIG. 3A shows the output state of the target speed signal of the high acceleration speed table (speed table 1) and the output state of the corresponding target speed signal of the linear motor drive signal. FIG. 3B shows the output state of the low acceleration speed table (speed table 2) and the output state of the target speed signal of the linear motor drive signal corresponding thereto. When the speed table 1 or 2 is selected, a target speed signal is output according to a predetermined output timing signal. The difference from the detected speed signal is calculated by the difference calculation means, and the difference signal is calculated via the phase compensation means 35.
Amplification means 36 and 37 are provided. Then, the amplifying unit 3 sets the moving speed of the optical head 10 to the target speed.
7 outputs a linear motor drive signal.

At the same time as outputting the target speed signal from time t0, a linear motor driving signal is also output. When the predetermined speed is reached, the linear motor drive signal becomes zero (0) and the target speed signal becomes a constant value. After a while, the target speed signal starts to decrease, and the linear motor drive signal starts to output a signal in the minus direction. Finally, the target speed signal becomes zero (0), and the linear motor drive signal also becomes zero (0).
become.

The difference between FIGS. 3A and 3B is that the speed table 1 has a greater slope of the target speed signal and the absolute value of the output voltage of the linear motor drive signal than those of the speed table 2. That is. Although only two speed tables are shown here, the speed pattern of the target speed signal in the speed table may have various patterns according to the difference between the current track and the target track. Good.

Next, the operation of the speed table switching means 34 will be described with reference to FIGS. First, upon receiving the access operation command, the control unit 20 outputs a control signal to the speed table switching means 34 so as to select the speed table 1 of the speed table means 33. Note that the speed table switching means 34 may output a selection signal for selecting a table of high acceleration as a default.

Therefore, first, the high acceleration speed table (speed table 1) shown in FIG. 3A is used, and the output of the target speed signal based on the speed pattern of the speed table 1 is started in response to the access start command. (At time t0). At the same time, the speed table switching means 34 monitors the drive voltage of the linear motor 11 and monitors whether the absolute value of the drive voltage exceeds a preset threshold (Vth1). If there is no disturbance or the like in the middle, the tracking actuator 5 according to the target speed of the high acceleration speed table 1 shown in FIG.
And the drive signal of the linear motor 11 are output, so that the access operation is performed at high speed.

Further, after the output of the target speed signal according to the speed table 1 is started, a disturbance such as the application of an external force occurs, and the absolute value of the driving voltage of the linear motor becomes equal to the threshold value (Vth
If 1) is exceeded (at time t1 in FIG. 4), the speed table switching means 34 switches the speed table from the high acceleration speed table (speed table 1) to the low acceleration speed table (speed table 2). The switching signal is output to the speed table means 33. Upon receiving the switching signal, the speed table means 33 switches to a low acceleration speed table (speed table 2) and outputs a target speed signal corresponding to the speed pattern data of the speed table 2.

Since the target speed signal at this time is the target speed at the time point t1 after the output of the target speed signal of the speed table 1 has started (time point t0), the target speed signal of the speed table 2 As the output, a target speed signal is output when it is assumed that the time t1 has elapsed since the start of the output from the time point t0 in the speed table 2. However, the output of the high acceleration speed table (speed table 1) is greater than the output of the low acceleration speed table (speed table 2) at the time point t1 after the start of the output.
Therefore, when the speed pattern is switched, the output of the speed pattern is controlled so that the value of the target speed signal before switching is continuously changed from the value of the target speed signal after switching.

That is, the output value of the speed table 1 is latched until the output value of the target speed signal of the speed table 2 becomes equal to the output value of the table 1 at the time t1, and the output value at the time t1 is maintained. to continue. When the output value of the speed table 2 becomes equal to the output value of the table 1 at the time point t1 with the passage of time (time point t2), after that, the speed table means 33 replaces the output value at the time point t1 with The target speed signal of the speed table 2 shown in FIG. The latch function may be provided in the speed table means 33, or another circuit means may be provided with this function.

Here, if the threshold value (Vth1) is set to a voltage value corresponding to the level of the limit value at which the drive current of the linear motor 11 is saturated, the drive current of the linear motor 11 will not be saturated. Thus, it is possible to execute a stable access operation without causing an access error.

In the above-described embodiment, the linear motor 11 is more effective than the tracking actuator 5.
The speed table switching means 34 monitors the drive signal of the linear motor 11 on the assumption that the output of the phase compensating means 35 is saturated at a low current value. However, when the tracking actuator 5 saturates at a lower current value, the speed table switching means 34 monitors the drive signal of the tracking actuator 5 so that when the speed signal exceeds the set threshold value (Vth2), May be switched. The threshold value at this time (Vth2)
Is the same as Vth1, the tracking actuator 5
May be set to a voltage value corresponding to the limit value at which the drive current of the above becomes saturated.

Further, speed table switching means 34
Counts the number of times the absolute value of the drive voltage of the monitored linear motor 11 or the tracking actuator 5 exceeds a threshold value, and generates a switching signal to switch the speed table when the number exceeds a preset number. It may be. Thus, the switching of the speed table does not occur due to high-frequency noise or the like, and a high-speed access operation can be realized.

The threshold at this time is set to the above-described threshold (Vth
The value is set as a value (Vth11) different from 1), and switching to the table 2 is performed when the absolute value of the driving voltage exceeds another threshold (Vth11) a predetermined number of times or exceeds the threshold (Vth1). You may do so.

As described above, according to the above-described embodiment, the drive current of the linear motor or the tracking actuator can be reduced even when disturbance such as generation of acceleration due to eccentricity of the disk, external vibration, and decrease in power supply voltage is applied. Does not saturate. Therefore, without deteriorating performance, an access error can be prevented and stable access control can be realized.

Even when the drive voltage of the actuator or the linear motor is low, a stable access operation can be performed without generating a saturation current, so that the power supply voltage of the device can be reduced and power consumption can be reduced.

The configuration described above is characterized by the configuration shown in the following supplementary note.

[Supplementary Notes] (1) Access control having speed control means for controlling the moving speed of the reading means for reading the information recorded on the recording medium by controlling the driving signal to the driving means of the reading means. A speed pattern for outputting as a target speed signal in response to a drive signal to the drive means when accessing a desired track on the recording medium; An access control device for controlling the moving speed of the reading means by switching from a speed pattern to another speed pattern.

(2) The access control according to (1), wherein the speed pattern is switched when the magnitude of the drive signal reaches a level at which the current flowing through the drive means is saturated. apparatus.

(3) When the speed pattern is switched,
3. The access according to claim 1, wherein the output of the speed pattern is controlled such that a change from the value of the target speed signal before switching to the value of the target speed signal after switching is continuous. Control device.

(4) When the speed pattern is switched,
Until the target speed signal after switching becomes the value of the target speed signal before switching at the time of switching so that the change from the value of the target speed signal before switching to the value of the target speed signal after switching is continuous. Additional item 3 characterized in that the value of the target speed signal before switching is maintained.
An access control device according to claim 1.

(5) An optical disk apparatus for moving an optical head having an objective lens in a radial direction of an optical disk by a moving mechanism and recording or reproducing information on or from the optical disk, wherein a drive signal to the moving mechanism is controlled. By
A control means for controlling a moving speed of the optical head, and a speed pattern for outputting as a target speed signal in response to a drive signal to the moving mechanism when a desired track on the optical disk is accessed, A target speed output unit that outputs the target speed signal by switching from a pattern to another speed pattern, and controls a drive signal to the moving mechanism based on the target speed signal from the target speed output unit. An optical disk device, wherein the moving speed of the optical head is controlled.

[0051]

As described above, according to the present invention,
Access errors can be prevented while maximizing performance, and reliability can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram of a storage device according to an embodiment of the present invention;

FIG. 2 is a block diagram of a speed control unit in FIG. 1;

FIG. 3 is a diagram showing changes in a target speed signal and a linear motor drive signal during track access of the storage device of FIG. 1;

FIG. 4 is a diagram showing changes in a target speed signal and a linear motor drive signal when there is a disturbance or the like;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Spindle motor 2 ... Optical disk 3 ... Optical spot 4 ... Objective lens 5 ... Tracking actuator 6 ... Laser diode 7 ... Collimator lens 8 ... Beam splitter 9 ... Tracking error detector 10 Optical head 11 Linear motor 12 Tracking error signal generating means 13 Phase compensating means 14 Speed control means 15 Coupling compensating means 16, 17 ... Switch circuits 18, 19 ... Driver 20 ... Control unit 31 ... Track counter 32 ... Speed detection means 33 ... Speed table means 34 ... Speed table switching means 35 ... Phase compensation means 36, 37 ... amplification means

Claims (3)

[Claims] 1. An access control device having a speed control means for controlling a moving speed of a reading means for reading information recorded on a recording medium by controlling a driving signal to a driving means of the reading means. The speed control means, when accessing a desired track on the recording medium, changes a speed pattern for outputting as a target speed signal according to a drive signal to the drive means from a certain speed pattern to another speed pattern. An access control device, wherein the moving speed of the reading means is controlled based on another switched speed pattern. 2. The access control device according to claim 1, wherein the switching of the speed pattern is performed when the magnitude of the drive signal reaches a level at which the value of the current flowing through the drive means is saturated. 3. An optical disk device for moving an optical head having an objective lens in a radial direction of an optical disk by a moving mechanism and recording or reproducing information on or from the optical disk, wherein a drive signal to the moving mechanism is controlled. Control means for controlling the moving speed of the optical head, and when accessing a desired track on the optical disc,
Target speed output means for outputting a target speed signal by switching a speed pattern for outputting as a target speed signal from a certain speed pattern to another speed pattern in accordance with a drive signal to the moving mechanism. An optical disc apparatus, wherein a drive signal to the moving mechanism is controlled based on the target speed signal from the target speed output means to control a moving speed of the optical head.