JPH06325554A - Access controller and control method - Google Patents

Abstract

PURPOSE:To shorten the access time of optical head by minimizing the rotation waiting time for a target sector after arriving at a target track. CONSTITUTION:The access controller comprises an optical head 3, a spindle motor 2 for rotating the optical disc at a variable speed, a seek mechanism for shifting the optical head 3, a seek time estimation unit 57 for operating the seek operation finishing time, and circuits 58-60, 61 for controlling the rotational speed of the spindle motor 2 under seek operation to minimize the rotation waiting time of the head 3 for a target sector upon finish of seek operation. The spindle motor 2 is controlled so that the optical head 3 is located immediately in front of the target sector at the moment when the seek operation finishes.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an access control apparatus and an access control method for an apparatus for driving a disk-shaped recording medium such as an optical disk apparatus, and more particularly to an access control apparatus and an access control method capable of shortening access time.

[0002]

2. Description of the Related Art As optical discs, compact discs (CDs) for audio, CD-ROMs (compact disc read-only memories), write-once optical discs, rewritable magneto-optical discs, etc. have been put to practical use, and they are used in various fields. Development for higher performance is being actively conducted.

An optical disk has a high recording density and can record a large capacity, but the track pitch is very narrow (1 to 2 μm). Therefore, it is necessary to form a minute light spot and control the positioning of the light spot with respect to the rotating optical disc with high accuracy.

The light spot is formed by making the emitted light of the semiconductor laser incident on the objective lens through an optical prism or the like and condensing it on the optical disk. The position of the light spot is controlled by detecting the position of the light spot in the focus direction (perpendicular to the surface of the optical disc) and the tracking direction (radial direction of the optical disc) with a photodetector and servo-controlling the actuator of the objective lens. It is realized by this.

Taking this point as an example of a CD-ROM (Compact Disc Read Only Memory) driving device, which has been attracting attention as a data reproducing device for a computer as a center of multimedia, with reference to FIGS. 8 to 11. explain.

FIG. 8 is a block diagram showing the structure of a CD-ROM drive device. In FIG. 8, reference numeral 1 is a CD-RO
M, 2 is a spindle motor, 3 is an optical head, 4 is an objective lens, 5 is an actuator, 6 is an objective lens actuator, 7 is a semiconductor laser, 8 is a beam splitter, 9 is a reflecting mirror, 10 is an astigmatic lens, 11 Is a light sensor,
12 is a tracking servo control unit, 13 is a focus servo control unit, 14 is a tracking control signal, 15 is a focus control signal, 16 is an information signal detection unit, 17 is a signal processing circuit, 18 is an interface control unit, 19 is an interface signal, 20 is an access / laser control unit, 21
Is a spindle motor control unit, and 22 is a controller.

The CD-ROM 1 is an access target,
Various information is recorded. Spindle motor 2 is C
Rotate the D-ROM1. The optical head 3 is composed of a mechanical section, an optical section, and the like. The mechanism section is composed of an actuator 5 for moving the objective lens 4 in the focus direction and the tracking direction and an objective lens actuator 6 in which the objective lens 4 is integrally formed. The optical section includes an objective lens 4, a semiconductor laser 7, a beam splitter 8, a reflection mirror 9, an astigmatism lens 10, and the like.

The light emitted from the semiconductor laser 7 enters the objective lens 4 through the beam splitter 8 and the reflection mirror 9, and C
A minute light spot is formed on the D-ROM 1. CD-
The reflected light from the ROM 1 returns to the objective lens 4 and the reflection mirror 9, the optical path of which is changed by 90 degrees by the beam splitter 8, and enters the optical sensor 11 through the astigmatism lens 10. The light receiving surface of the optical sensor 11 is divided into a plurality of parts in order to detect the positional deviation of the light spot in the focus direction and the positional deviation in the track direction.

The output signal of the optical sensor 11 is supplied to the tracking servo control unit 12, the focus servo control unit 13, and the information signal detection unit 16. The tracking servo control unit 12 generates a tracking control signal 14 from the output signal of the optical sensor 11. This tracking control signal 14
Is supplied to the objective lens actuator 6 to control the position of the objective lens 4 in the tracking direction. On the other hand, the focus servo control unit 13 generates the focus control signal 15 from the output signal of the optical sensor 11. This focus control signal 15 is supplied to the objective lens actuator 6,
The position of the objective lens 4 in the focus direction is controlled.

The information signal detector 16 reproduces the information signal from the output signal of the optical sensor 11 and supplies it to the signal processing circuit 17. The signal processing circuit 17 responds to the reproduced information signal by
Processing such as modulation / demodulation and data error correction is performed. The signal processing circuit 17 sends the processed signal as an interface signal 19 to a host device such as a personal computer through the interface control unit 18.

The recorded information on the CD-ROM 1 is recorded at the same density over the entire area. Therefore, the CD-R
In order to reproduce the data written in each track of the OM1, it is necessary to read each track having a different radius at a constant speed. Therefore, the spindle motor control unit 21
Controls the rotation of the spindle motor 2 so that the CD-ROM 1 rotates at a constant linear velocity.

The access / laser control unit 20 controls the semiconductor laser 7 by moving the optical head 3 to a predetermined track of the CD-ROM 1 by a linear motor or the like integrated with the optical head 3. The controller 22 controls each block in FIG.

When such a CD-ROM drive device is used as an external storage device for a computer or the like, it is necessary to improve the throughput of the entire system, and therefore the operation of the CD-ROM drive device must be accelerated. The problem arises. For that purpose, it is required to speed up the operation of moving the optical head 3 onto the target sector (hereinafter referred to as “access”).

The access method will be described with reference to FIG. FIG. 9 is a diagram showing an access sequence of a conventional access control device. As shown in FIG. 9, the access is roughly divided into a rough seek (FIG. 9A) and a dense seek (FIG. 9B). (Fig.) And waiting for rotation (Fig. 9 (c)).

In the rough seek operation, the optical head 3 (more precisely, the optical spot formed on the CD-ROM 1 by the optical head 3) is positioned from the track 24 where the target sector 25 is positioned to the target track where the target sector 25 is positioned. This is an operation of greatly moving it to the vicinity of 26 (for example, the track 27 shown by the broken line). The dense seek is an operation for performing accurate positioning so that the optical head 3 is moved from the adjacent track 27 to the target track 26. The waiting for rotation is an operation of waiting for the target sector 25 to reach the optical head 3 as the CD-ROM 1 rotates after the optical head 3 reaches the target track 26.

The moving speed and the moving amount of the optical head 3 during the rough seek and the fine seek are controlled by counting the number of traverse tracks. The counting of the number of crossing tracks is performed using, for example, the track crossing signal shown in FIG.

FIG. 10A shows a sectional view of the CD-ROM 1. In FIG. 10A, reference numeral 28 is a CD-ROM
1 shows the center of the track, 29 is a non-recording portion between tracks, and 32 and 33 are edge portions of the tracks. When the light spot is applied to the center 28 of the track or the center of the non-recorded portion 29, the track crossing signal becomes the reference level. Further, when the light spot is applied to the edge portions 32 and 33, the peak value becomes positive or negative. Therefore, FIG.
One cycle of the track crossing signal shown in 0 (b) corresponds to the optical head 3 crossing one track. The number of tracks crossed can be known by counting the number of waves of this track crossing signal. Further, the moving speed of the light spot can be detected by measuring the frequency or the cycle of the track crossing signal, which can be used for controlling the moving speed of the light spot.

Next, an access control method in the conventional CD-ROM drive will be described with reference to the block diagram of the access control device of FIG. In FIG. 11, reference numeral 34
Is a command signal, 35 is a residual track counter, 36 is a target speed generator, 37 is a cross-track signal converter, 38 is a cross-track signal detector, 39 is a speed detector, 40 is a comparator, 41 is a period counter, 42 is a moving speed converter, 43 is a head drive amplifier, 44 is a drive signal, 45 is a spindle motor controller, and 46 is a spindle driver.

First, the host device or the like sets the distance to the target track, that is, the number of tracks from the current track to the target track in the remaining track counter 35 via the command signal 34. The target speed generator 36 sets a target value of the moving speed of the optical head 3 according to the value of the remaining track counter 35, and supplies it to the comparator 40. The remaining track counter 35 is a counter indicating the number of remaining tracks up to the target track, and subtracts the count value according to the pulse signal supplied from the track crossing signal converter 37 according to the movement of the optical head 3.

The track crossing signal detector 38 generates a track crossing signal shown in FIG. 10B from the output signal of the optical head 3. The track crossing signal is converted into a pulse signal by the track crossing signal converter 37 and supplied to the remaining track counter 35. The remaining track counter 35 subtracts the count value according to the number of supplied pulses.

This pulse signal is also supplied to the speed detector 39. The speed detector 39 is composed of, for example, a cycle counter 41 that calculates the cycle of the pulse signal from the track crossing signal converter 37 and a moving speed converter 42 that calculates the moving speed according to this cycle. The actual moving speed of the optical head 3 is detected based on the pulse signal from the device 37, and this is supplied to the comparator 40.

The comparator 40 successively compares the actual moving speed and the target value of the moving speed from the target speed generator 36 to obtain a difference signal between them. The head drive amplifier 43 amplifies this difference signal and sends it to the optical head 3 as a drive signal 44. The optical head 3 servo-controls the moving speed of the optical head so that the difference signal becomes zero, and performs access by optimal speed control.

In the rough seek operation, a slight error occurs in the track movement, and the light spot may stop before the target track or go too far. In such a case, the optical head 3 reads the signal recorded on the track, recognizes the track number of the current track, and corrects the movement to the target track. This corresponds to a dense seek. When the light spot is located on the target track due to the dense seek, the recording signal of the track is read again to recognize the track number and the sector. Then, the rotation of the target sector is waited until it reaches the light spot as the CD-ROM 1 rotates, and finally the recording signal of the target sector is read. This is a series of access operations.

Since it is necessary to control the rotation of the CD-ROM 1 at a constant linear velocity, the spindle motor controller 45 is given the rotational velocity of the target track as a command value at the start of access. In response to this command value, the spindle driver 46 gives a drive signal to the spindle motor 2 and controls so that the rotational speed of the CD-ROM 1 coincides with the command value in parallel with the seek operation.

Generally, the rotation speed of the CD-ROM 1 is controlled by phase locked loop (PLL) control. That is, the sync signal is recorded on the CD-ROM 1 at regular intervals on the track, and the linear velocity can be kept constant by controlling the spindle motor 2 so that the sync signal is read at a constant cycle during reproduction. . During seek, the cycle of the synchronizing signal changes with the movement of the optical head 3. If the rotation speed of the spindle motor 2 is made to follow the cycle so that this cycle becomes constant, the rotation speed control is automatically performed. Will be seen.

[0026]

As described above, in order to speed up the access of the optical head, the moving speed of the optical head is increased so that the optical head reaches the target track more quickly and the target sector is read. Must be able to start. Therefore, efforts are being made to reduce the size and weight of the optical head and perform faster seek. However, since the access operation is composed of the seek operation and the rotation wait operation, it is not sufficient to speed up only the seek operation, and as described below, the rotation wait operation must be speeded up. In some cases there will be.

This point will be described below with reference to FIG. FIG. 12 is a diagram for explaining a problem in the conventional access control device, and FIG. 12 (a) shows a state at the start of access. Reference numeral 3 is an optical head at the current position, 48 is a target track 49. Indicates the target sector located. Further, in response to the access command, a rough seek and a dense seek are performed, and after 1 hour, the optical head 3 makes the target track 4
FIG. 12B shows the state in which the number 9 has been reached. At this time, the target sector 48 comes immediately after the optical head 3 due to the rotation of the disk. Therefore, in order for the target sector 48 to reach the optical head, the rotation of the CD-ROM 1 causes the target sector 4 to move.
You must wait until 8 is in the position shown in Figure 12 (c). In this case, the rotation waiting time corresponds to the time required for the CD-ROM 1 to make one rotation.

Normally, the linear velocity of the CD-ROM 1 is 1.2 m.
/ S to 1.4 m / s, which corresponds to 200 to 500 rpm from the outer peripheral portion to the inner peripheral portion of the disk when converted to the rotational speed, and the rotation waiting time is 120 to 300 ms.
In order to increase the data transfer speed, a method of doubling the rotation speed is also used, but the rotation waiting time is still extremely long at 150 ms in the worst case.

As described above, there is a problem in that even if only the seek time is increased, the total access speed cannot be increased due to the rotation waiting time, so that the speed of the CD-ROM drive cannot be increased. This point is
The same applies to other optical disk drive devices, not limited to the CD-ROM drive device.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an access control device and an access control method that enable high-speed access to a disk-shaped storage medium, particularly an optical disk.

[0031]

In order to achieve the above-mentioned object, an access control apparatus according to the present invention comprises seek time estimating means for estimating and calculating a completion time of a seek operation in which a head moves to a track having a target sector. A rotation speed control means for controlling the rotation speed of the spindle motor during the seek operation based on the estimated completion time of the seek operation,
The rotation speed of the spindle motor is controlled so that the rotation waiting time from the completion of the seek operation until the head reaches the target sector is minimized.

Further, the access control device according to the present invention comprises:
In order to achieve the above object, the rotation speed control means calculates in advance the rotation waiting time required to reach the target sector after the completion of the seek operation of the head, and the rotation speed of the spindle motor is accelerated or decelerated according to the calculation result. And means for controlling.

Further, the access control device according to the present invention comprises:
In order to achieve the above object, there is provided a speed profile storage means for storing a speed control law of acceleration / deceleration of the rotation speed control means according to at least one of a rotation waiting time, a seek time, and a moving distance of the head, and the storage thereof. It is characterized in that the rotation speed of the spindle motor is controlled according to the contents.

Further, in order to achieve the above object, the access control method according to the present invention estimates and calculates the completion time of the seek process of moving the head to the track where the target sector is located, and the estimated completion time of the seek process. On the basis of the above, the step of controlling the rotation speed of the disk-shaped storage medium during the seek process so that the rotation waiting time from completion of the seek operation of the head to reaching the target sector is minimized.

The present invention is configured as described above, estimates the completion time of the seek operation for the target track of the head, and based on this, by controlling the rotation speed of the spindle motor during the seek operation, the head is completed when the seek operation is completed. Is located immediately before the target sector and the rotation waiting time is minimized, so that the head can access the target sector at high speed.

Further, according to the present invention having the above-mentioned structure, the rotation waiting time required to reach the target sector after the completion of the seek operation of the head is calculated in advance, and the rotation speed of the spindle motor is accelerated or decelerated according to the calculation result. In this way, by making the rotation waiting time the shortest, the head can access the target sector at high speed.

Further, the present invention is configured as described above, and stores the speed control law of acceleration / deceleration of the rotation speed control means in accordance with at least one of the rotation waiting time, the seek time, and the moving distance of the head. Thus, by controlling the rotation speed of the spindle motor, the head can access the target sector at high speed with simple control.

Further, the method of the present invention is configured as described above, and estimates the completion time of the seek process in which the head moves to the target track, so that when the seek operation of the head is completed, the head is already in front of the target sector. Since the head rotation waiting time is minimized by arranging the head position, the head can access the target sector at high speed.

[0038]

An embodiment of the present invention will be described in detail below with reference to the accompanying drawings. First, regarding the principle of speeding up access of the optical head by the access control device of the embodiment,
This will be described with reference to FIGS. 2 and 3.

FIG. 2A shows the CD-RO before the start of access.
2B is a diagram showing the positional relationship between M and the optical head, FIG. 2B is a diagram showing the positional relationship between the CD-ROM and the optical head when the seek operation is completed, and FIG. 3 is a rotational speed control of the spindle motor according to an embodiment of the present invention. 3A and 3B are timing charts for explaining the method, FIG. 3A is a diagram showing a normal rotation speed control method using a synchronization signal, and FIG. 3B is a diagram showing a rotation speed control method of this embodiment. FIG. 3C is a diagram showing a modified example.

In FIG. 2, reference numeral 1 is a CD-ROM, 3
Is an optical head, 64 is a target sector, and 65 is a target track on which the target sector is located. In the example of FIG. 2, the optical head 3
When the target sector 65 reaches the target track 65, the target sector 64 is located past the optical head 3, the rotation waiting time becomes long, and high speed access is hindered.

Therefore, in the present embodiment, as shown in FIG. 3, the seek time t1 is predicted, the rotational speed of the spindle motor 2 during the seek operation is controlled (adjusted), and the target sector is completed at the time of completion of the seek operation. CD-ROM 64 so that 64 is located at a position 67 (FIG. 2B) in front of the optical head 3.
Controls the rotation of 1. In this way, the rotation waiting time can be shortened and high speed access can be achieved. The moving speed of the optical head 3 is controlled according to the optimum speed profile according to the difference between the current track and the target track. Therefore, the seek time can be almost uniquely predicted according to the number of traversing tracks.

As shown in the example of FIG. 2, when the optical head 3 moves from the inner circumference to the outer circumference, since the tracks on the outer circumference side are read at the same speed, the rotation speed of the CD-ROM 1 is reduced and the seek operation is completed. In the above, the rotation speed of the CD-ROM 1 must match the rotation speed specific to the target track. Therefore, conventionally, as shown in FIG. 3A, the rotation speed is changed from the speed V1 (the rotation speed peculiar to the track before the movement) to V2 (the target speed) so that the synchronization signal reproduced from the CD-ROM 1 has a constant cycle. The rotation speed of the truck was reduced to a certain rate.

However, in this embodiment, for example, as shown in FIG.
As shown in (b), the rotation speed is reduced to V2 by time t2 (t2 <t1). By controlling the rotation speed in this way, the moving distance of the target sector with respect to the optical head 3 during the rotation waiting period becomes shorter than that in the conventional case, and the target sector can be positioned in front of the optical head 3 when the seek operation is completed. become.

As shown in FIG. 3 (c), when the optical head 3 moves from the outer circumference to the inner circumference, the reading speed is made to be the same as the above case, so that the rotation speed of the CD-ROM 1 is changed. It is necessary to increase to the rotation speed specific to the target track. Therefore, the position of the target sector at the time of completion of the seek operation can be controlled by adjusting the time t2 until the rotation speed reaches the target value on the high speed side.

Time t2 is seek time t1, current sector,
It can be calculated based on the target sector. The seek time, the moving distance of the optical head, the rotation waiting time when the rotation speed is normally controlled, and the like, the time t2 is calculated or measured in advance and stored in the memory, and the stored seek is stored as necessary. The time t1 may be read.

Next, the configuration of the access control device that enables the above access control will be described with reference to the block diagram of FIG. In FIG. 1, reference numeral 50 is a track crossing signal detector, 51 is a track crossing signal converter, 52 is a speed detector, 53 is a comparator, 54 is a residual track counter, and 55.
Is a target speed generator, 56 is a head drive amplifier, 57 is a seek time estimator, 58 is a rotation waiting time calculator, 59 is a rotation speed controller, 60 is a spindle driver, and 61 is a controller.

When an access command signal is output from the host device or the like to the controller 61, the controller 61 inputs the sector number, the track number, the target sector and the target track number where the optical head 3 is currently located, to the seek time estimator 57. At the same time, the number of moving tracks to the target track is set in the remaining track counter 54. As a result, control of the optical head 3 and the spindle motor 2 is started.

First, the control of the optical head 3 will be described. The remaining track counter 54 is an up / down counter, and as described above, the number of moving tracks to the target track is initialized at the start of access. Depending on the count value of the remaining track counter 54, the target speed generator 5
5 is according to a pre-optimally designed speed profile,
The target speed of the optical head 3 is set, and this target speed is supplied to the comparator 53 as a command value of the moving speed of the optical head 3.

The comparator 53 uses this command value and the speed detector 52.
The actual moving speeds of the optical heads 3 supplied from the above are sequentially compared, and a difference signal corresponding to the difference is output. This difference signal is amplified by the head drive amplifier 56 and supplied as a drive signal 62 to the actuator of the optical head 3. The actuator controls the moving speed of the optical head 3 in the tracking direction so that the difference signal becomes zero.

The track crossing signal detector 50 outputs a sinusoidal track crossing signal corresponding to the movement of the optical head 3 based on the output signal of the optical head 3. The track crossing signal converter 51 converts this track crossing signal into a pulse signal and supplies it to a speed detector 52 and a residual track counter 54.

The remaining track counter 54 subtracts the count number corresponding to the pulse number of the pulse signal supplied from the track crossing signal converter 51, and updates the remaining track number up to the target track. The target speed generator 55 resets a new target speed according to the number of remaining tracks and the speed profile, and supplies this set value to the comparator 53 as a command value of a new moving speed of the optical head 3.

The speed detector 52 detects the actual moving speed of the optical head 3 based on the pulse signal from the track crossing signal converter 51. The speed detector 52 detects the actual moving speed of the optical head 3 by counting the period and frequency of the track crossing signal, similarly to the speed detector 39 of FIG.

As described above, the actual moving speed detected by the speed detector 52 is supplied to the comparator 53, successively compared with the speed command value, and fed back to the optical head 3 so that the difference signal becomes zero. The moving speed of the optical head 3 is controlled. Through the series of feedback control operations, the coarse seek operation and the fine seek operation of the optical head 3 are controlled.

Next, the control method of the spindle motor 2 will be described in detail based on the same method. As described above, in response to the access command signal, the controller 61 inputs the sector number, the track number, the target sector, the target track number, etc., where the optical head 3 is currently positioned, to the seek time estimator 57. The seek time estimator 57 calculates the seek time t from the current track number and the target track number.
Ask for 1.

On the other hand, the rotation waiting time calculator 58 calculates the seek time t1, the target sector number, the current sector number, etc.
The rotation waiting time when the normal rotation speed control (speed control performed based on the synchronization signal recorded in the CD-ROM 1) is performed is calculated. For the rotation waiting time, the relationship between the seek time t1, the current sector number, the target sector number, etc. and the rotation waiting time etc. is obtained by experiment or calculation and stored in a memory or the like.
The parameters may be set in advance, and the memory contents may be read out and obtained.

The rotation speed controller 59 calculates the rotation waiting time based on the rotation waiting time calculated by the rotation waiting time calculator 58.
The time t2 in (b) is calculated. For example, when the rotation waiting time calculated by the rotation waiting time calculator 58 is close to zero, t2 and t1 are equalized, and when the rotation waiting time is long, the time t2 is determined according to the length. Rotation waiting time,
The relationship between the current rotation speed of the track and the rotation speed of the target track, and the time t2 is obtained in advance by experiments or calculations and stored in a memory or the like, parameters are set, the contents of this memory are read out later, and the time t2 is read. May be requested.

The rotation speed controller 59 controls the spindle driver 60 based on the obtained data, and the CD-ROM
Control the rotation speed of 1.

The change in the rotation speed of the spindle motor 2 is not limited to the example shown in FIG. 3 (b).
It may have a complicated profile as shown by the solid line and the broken line.

Next, based on FIG. 4, the rotation speed controller 59
An example of the control signal supplied to the spindle driver 60 will be described in detail. FIG. 6 is a waveform diagram of control waveforms used for control by the method of controlling the rotation speed of the spindle motor according to the embodiment of the present invention.

The spindle driver 60 controls the rotation speed of the spindle motor 2 according to a control signal as shown in FIG. 4, for example. In FIG. 4, the horizontal axis represents time t, the vertical axis represents the voltage level of the control signal, and the symbol t41 represents the access disclosure time. In the period t40 before the access is started, the rotation control of the spindle motor 2 is performed by the phase locked loop (PLL) based on the data read from the CD-ROM 1.
It is done by control. That is, the spindle driver 60 is supplied with the sync signal reproduced from the CD-ROM 1, and the spindle driver 60 controls the spindle motor 2 so that the cycle of the sync signal becomes a predetermined cycle.

At the start of access (time t41), the phase locked loop (PLL) control is stopped and switched to open loop control. The spindle motor is in the target speed control mode state during this open loop control period. In this target speed control mode, the spindle driver 60 is controlled by positive and negative control pulses as shown in FIG. The positive pulse becomes a signal instructing acceleration of the spindle motor, and the negative pulse becomes a signal instructing deceleration (brake).

The rotation speed controller 59 controls the rotation speed of the spindle motor 2 via the spindle driver 60 by controlling the pulse width or peak value of the positive and negative pulses. In this example, this control is performed by controlling the pulse width Ta of the acceleration pulse, the pulse width Tb of the deceleration pulse, and the switching time t42. After the end of the open loop control, the mode is switched to the phase locked loop (PLL) control mode again, and the rotation speed is controlled according to the synchronizing signal reproduced from the CD-ROM 1.

Next, an example of the structure of the rotation speed controller 59 for generating the control signal shown in FIG. 4 will be described with reference to FIG. The rotation speed controller 59 shown in FIG. 5 gives a speed profile by inputting how long each of the series of sequences starting from acceleration of the spindle motor, deceleration, and settling to the target speed is performed. Composed.

In FIG. 5, reference numeral 70 is a designated time input signal, 71 is an arithmetic unit, 72 is a switching time memory, 73 is an acceleration pulse generator, 74 is a deceleration pulse generator, 75 is a changeover switch, and 76 is a control signal. Indicates.

The designated time input signal 70 is the rotation waiting time,
It includes all or part of information such as seek time, optical head movement distance, target track rotation speed, and movement source track rotation speed. The switching time memory 72 is a random access memory (RAM) or a read only memory (ROM).
And stores data such as pulse widths Ta and Tb of the acceleration pulse and the deceleration pulse for each combination of parameters. The data stored in the switching time recorder 72 can be obtained by calculation based on the torque characteristics of the spindle motor.
It is also possible to measure the time until the motor is settled according to the switching timing and the pulse width by trial drive and use this as the stored data. This trial is performed when the device is assembled or when the device is started.

The arithmetic unit 71 reads the stored data of the switching time storage unit 72 based on the designated time input signal 70, and outputs the switching control signal to the changeover switch 7 based on the read data.
Supply to 5.

The acceleration pulse generator 73 and the deceleration pulse generator 74 are circuits that generate a positive voltage and a negative voltage, for example. The changeover switch 75 is responsive to the changeover control signal from the arithmetic unit 71 to generate the acceleration pulse generator 73 and the deceleration pulse generator 7.
4 output is selected and supplied to the spindle driver 60 as a control signal 76. Spindle driver 60 uses control signal 7
According to 6, the rotation speed of the spindle motor 2 is controlled. In this way, a control signal for open loop control can be generated.

Next, a specific example of the access control method according to this embodiment will be described in detail with reference to FIGS. 6 and 7.
FIG. 6 is a flow chart showing a specific example of an access control method according to an embodiment of the present invention, and FIG. 7 is used to explain a specific example of the access control method according to an embodiment of the present invention. It is a top view of CD-ROM which shows a relationship. When the seek time estimator 57 determines the seek time t1 to the target track, the rotation waiting time calculator 58 and the rotation speed controller 59 start the control operation shown in the flowchart of FIG.

First, the rotation waiting time calculator 58 calculates the position of the target track after t1 hours when the rotation speed control (FIG. 3 (a)) based on the normal synchronizing signal is performed (step S1). Then, it is determined whether or not this position is in the region 77 shown in FIG. 7, that is, at a position past the optical head 3 (step S2). In step S2, when the determination result is “No”, that is, when the rotation waiting time is short even with the normal rotation speed control, the rotation speed controller 59 uses the normal synchronization signal to control the rotation speed (FIG. 2 (a)). ) Is performed (step S3).

In step S2, if the determination result is "yes", that is, if the rotation waiting time becomes long in the normal rotation speed control, the rotation waiting time calculator 58 is used.
Calculates the position of the target sector after t1 hours when the spindle motor 2 is controlled by maximum acceleration / deceleration (deceleration when seeking from the inner circumference to the outer circumference and acceleration when seeking from the outer circumference to the inner circumference). (Step S4).

The rotation speed controller 59 determines whether or not the position of the target sector after the time t1 is within the area 78 of FIG. 7 (step S5), and if "yes", waits for rotation according to this control law. It is determined that the time can be shortened, and the open loop control described with reference to FIG. 4 is executed (step S
6). On the other hand, in the case of "no", the rotation speed controller 59 determines that the control by the maximum acceleration / deceleration has no effect, and performs the rotation speed control using the normal synchronization signal (step S6).
The rotation waiting time is controlled as described above.

Although the embodiment of the present invention has been described in detail with reference to FIGS. 1 to 7, the seek time estimator 57, the rotation waiting time calculator 58, and the rotation speed controller 59 shown in FIG.
Can be configured by software, or can be performed by processing by software in the controller 61.

It is also possible to incorporate variable parameters such as the environmental temperature condition, the inclination of the apparatus, the type of disk, etc. into the control law calculation, and in this case, it is possible to realize higher performance control. Become.

In the present embodiment, the case of performing access at a relatively long distance has been described as an example, but the present invention is applied to access when there is a target sector on an adjacent track such as a track jump operation. It is also possible to do so.
Further, although the description has been given centering on the CD-ROM as an example of the optical disc, the present invention can be similarly applied to other optical discs. Further, it is similarly applicable to magnetic disk devices such as hard disk devices and floppy disk devices.

[0075]

The present invention is configured as described above, and in particular, the rotation waiting time in the target track is minimized to shorten the access time of the optical head with respect to the target track and to speed up the access operation. Became possible.

[Brief description of drawings]

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

FIG. 2 is a plan view of a CD-ROM showing a positional relationship between a track and an optical head, which is used for explaining a rotation waiting time shortening method according to an embodiment of the present invention. FIG. Figure (b) shows the state when the seek is completed

FIG. 3 is a timing chart used for explaining a rotation speed control method of a spindle motor according to an embodiment of the present invention, FIG. 3A is a view showing a normal rotation speed control method using a synchronization signal, and FIG. The figure which shows the rotation speed control method of this Example, (c) is a figure which shows a modification.

FIG. 4 is a waveform diagram of control waveforms used for control by a rotation speed control method for a spindle motor according to an embodiment of the present invention.

FIG. 5 is a block diagram showing a configuration of a rotation speed controller according to an embodiment of the present invention.

FIG. 6 is a flowchart showing a specific example of an access control method according to an embodiment of the present invention.

FIG. 7 is a plan view of a CD-ROM showing a positional relationship between a track and an optical head, which is used for explaining a specific example of an access control method according to an embodiment of the present invention.

FIG. 8 is a block diagram showing a configuration of a conventional CD-ROM drive device.

9 is a plan view of a CD-ROM showing a positional relationship between a track and an optical head for use in explaining an access sequence of a conventional access control device. FIG. 9A is a diagram showing a rough seek operation, and FIG. Diagram showing seek operation (c) Diagram showing rotation waiting operation

FIG. 10 is a diagram showing a method of controlling a moving speed of an optical head in a conventional access control device, in which (a) is a sectional view of an optical disk and (b) is a waveform diagram of a track crossing signal.

FIG. 11 is a block diagram showing a configuration of a conventional access control device.

FIG. 12 is a plan view of a CD-ROM showing a positional relationship between a track and an optical head, which is used for explaining a problem in a conventional access control device.

[Explanation of symbols]

1 CD-ROM (compact disc read-only memory) 2 spindle motor 3 optical head 4 objective lens 5 actuator 6 objective lens actuator 7 semiconductor laser 8 beam splitter 9 reflection mirror 10 astigmatism lens 11 optical sensor 12 tracking servo control unit 13 focus Servo control unit 16 Information signal detection unit 17 Signal processing circuit 18 Interface control unit 20 Access / laser control unit 21 Spindle motor control unit 22 Controller 35 Residual track counter 36 Target speed generator 37 Track crossing signal converter 38 Track crossing signal detector 39 speed detector 40 comparator 41 cycle counter 42 moving speed converter 43 head drive amplifier 45 spindle motor controller 46 spindle drive 50 track crossing communication No. detector 51 Track crossing signal converter 52 Speed detector 53 Comparator 54 Residual track counter 55 Target speed generator 56 Head drive amplifier 57 Seek time estimator 58 Rotation waiting time calculator 59 Spindle speed controller 60 Spindle driver 61 Controller 71 Calculation unit 72 Switching time memory 73 Acceleration pulse generator 74 Deceleration pulse generator 75 Changeover switch

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Koji Muraoka 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (4)

[Claims] 1. An access control device for allowing a head to access an arbitrary sector of a disk-shaped storage medium, the head accessing the disk-shaped storage medium, a spindle motor for rotating the disk-shaped storage medium at a variable speed, A moving mechanism for moving the head, a seek time estimating means for estimating and calculating a completion time of a seek operation in which the head moves to the track where the target sector is located by the moving mechanism, and a seek operation completion time based on the estimated and calculated seek operation completion time And a rotation speed control means for controlling the rotation speed of the spindle motor during the seek operation so as to minimize the rotation waiting time from the completion of the seek operation until the head reaches the target sector. Access control device. 2. The rotation speed control means calculates a rotation waiting time required for the head to reach the target sector after completion of a seek operation, and the rotation speed of the spindle motor according to the calculation result. The access control device according to claim 1, further comprising means for controlling acceleration / deceleration. 3. A speed profile storage means for storing a speed control law for acceleration / deceleration of the rotation speed control means in accordance with at least one of a rotation waiting time, a seek time, and a head moving distance, and the rotation speed control. 3. The means controls the rotational speed of the spindle motor according to the contents stored in the speed profile storage means.
The access control device described. 4. An access control method for accessing an arbitrary sector of a disk-shaped storage medium by a seek step of moving the head to a track where a target sector is located, and a step of estimating and calculating a completion time of the seek step. And, based on the estimated completion time of the seek step, the rotation speed of the disk-shaped storage medium during the seek process is set so as to minimize the rotation waiting time from the completion of the seek operation until the head reaches the target sector. An access control method comprising: a controlling step.