JPH09115256A - Disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To speedily and stably seek a target track in a disk device provided with a seek control mechanism for a head between tracks on a recording medium. SOLUTION: A feed motor for moving a pickup is rotated at the max. rated output from a seek starting time t0 to a preset deceleration starting time t1 , and is then decelerated from t1 to an objective position at t2 with a deceleration control signal of speed corresponding to a moving amt. stored previously in a ROM by an MPU. Then, upon arrival of the pickup in the objective position t2 , a supply period T2 of a brake control signal corresponding to a speed just prior to the arrival is calculated, and this brake control signal is supplied so as to position the pickup in the target track position at t3 .

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk device having a mechanism for controlling the seek of a head between tracks on a recording medium.

[0002]

2. Description of the Related Art In recent years, in a disk device for driving a high density recording disk medium such as a CD-ROM, a seek for moving a pickup between tracks of the disk medium is controlled by an open loop control system. Therefore, it is desired to perform such seek at high speed and stably.

Here, FIG. 6 is a plan view of an essential part of an example of a conventional disk device. Further, FIG. 7 shows a plan view of a main part below the pickup feed mechanism of FIG. A disk device 11 shown in FIG. 6 shows a configuration in which a disk medium such as a CD-ROM is used, and a drive unit including a pickup unit 13 and a turntable 14 above a sub-chassis provided in the chassis 12. 1
5 are provided. The opening 1 is provided above the drive unit 15.
A base 16 on which a 6a is formed is arranged, and a tray 17 having a stepped facing surface 17a on which a CD-ROM is mounted and an opening 17b is arranged above the base 16. The tray 17 is movable in the direction of the front bezel 18 by a movable portion (not shown).

As shown in FIGS. 6 and 7, the drive unit 15 is provided with a pickup drive section 19 on the lower surface of a base 16, and the pickup drive section 19 includes a feed motor 20 for pickup feed and a plurality of gears. The transmission mechanism 21, the lead screw 22 driven via the transmission mechanism 21, and the guide shaft 23 extending to the lead screw 22 so as to be a plane and guiding the pickup unit 13.

The pickup unit 13 is such that the pickup 25 having the objective lens 25a exposed to the opening 16a side is mounted on the sled 24, and one side of the sled 24 engages with the lead screw 22. Is formed, and the other side is formed with an engaging portion 24b that engages so as to sandwich the guide shaft 23. The objective lens 25a forming the pickup 25 is suspended in the pickup 25 by a wire or the like in order to perform focusing and tracking.

Further, the pickup 25 is a connector 25b for exchanging read data, focusing and tracking control signals with a control board (not shown).
Is provided, and the flexible cable 26 is connected to the connector 25b.

On the other hand, the turntable 14 is provided with a drive motor (not shown in the figure) in the lower part thereof, and the disk medium clamped on the turntable 14 by the drive motor is rotated at a constant rotation speed. It is driven at a constant speed. In such a disc device 11, when the pickup unit 13 is moved between the tracks of the disc medium clamped on the turntable 14, the feed motor 2 is used.
0 is driven to rotate the lead screw 22 to position the pickup unit 13 at a predetermined position. This feed control is performed by the feed motor 2 at a predetermined timing.
This is performed by an open loop control method in which 0 is turned on / off with a constant current.

Therefore, FIG. 8 shows an explanatory view of the conventional feed motor drive control of the disk device. FIG. 8A is a waveform diagram of the control current, and FIG. 8B is a state diagram of the speed of the pickup unit. Now, when the control current is supplied to the feed motor 20 at the seek start t ₀ , the pickup unit 13 gradually increases the speed, and when the speed reaches a speed corresponding to the control current, the pickup unit 13 maintains the speed until the supply of the control current is stopped. And move.

Then, the track jump is read by the pickup unit 13, the count is counted, and when the pickup unit 13 is located on the target track (t ₁ ), the supply of the control current is stopped, but the feed motor 20 and The inertia of the transmission mechanism 21 causes an overshoot t _OV1 . In order to return the movement of the overshoot, currents with different polarities (reverse rotation) are supplied (t ₂ ~
Reseek by performing t ₃ ). This re-seek also causes a considerable amount of overshoot (t _OV2 ), and the overshoot correction is repeated to such an extent that it does not pose a problem.

[0010]

However, although the overshoot of the pickup section 13 is corrected as described above, the pickup section 13 cannot stabilize the convergence to the target track and the positioning is performed to some extent. There is a problem that it takes time to achieve high speed.

Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide a disk device for speeding up and stabilizing seek to a target track.

[0012]

In order to solve the above-mentioned problems, in the present invention, the head moved by the moving means is provided with the function of controlling and moving the head to the target track of the storage medium by the open loop method. In the disk device,
A storage unit that stores in advance movement speed information of the head with respect to a movement amount of the head in a predetermined section, and information regarding the movement of the head is calculated based on track information read when the head moves, A first control signal for initial control, which is output to the moving means based on moving speed information from the storage means at the start of movement according to the moving amount of the head, and a moving speed from the storage means according to the position of the head A second control signal for decelerating a predetermined movement period until the start of braking, which is performed immediately before the head reaches the target track based on the information, and reverses the movement means after a predetermined period after the supply of the second control signal is stopped. A disk device is configured to have a control means for supplying a third control signal for directional driving to position the head on the target track.

According to a second aspect of the present invention, the first and third control signals supplied by the control means according to the first aspect are signals which should drive the moving means to a maximum rated output. In the third aspect, the third control signal supplied from the control means according to the first or second aspect corresponds to the moving speed of the head immediately before the stop of the second control signal, which is stored in the storage means. It is supplied in the time obtained by multiplying by a constant.

As described above, according to the first aspect of the invention, the control means supplies the first control signal at the start of movement based on the track information by the movement of the head, and when the head moves to a predetermined position, the storage means A third control signal for decelerating based on the moving speed information of No. 3 and driving the moving means in the reverse direction for a predetermined period after the supply of the second control signal is stopped.
Supply the control signal of. This enables the head to be stably converged on the target track without overshooting despite the open loop control method.
The time until convergence can be shortened, and seek and access can be speeded up.

According to the second aspect of the invention, the moving means is driven to the maximum rated output by the supply of the first control signal at the start of driving the moving means and the third control signal for driving in the reverse direction. As a result, it is possible to increase the speed by shortening the time required for the head to converge on the target track.

According to the third aspect of the invention, the supply time of the third control signal can be calculated by multiplying the moving speed of the head immediately before the stop of the second control signal by a preset constant. As a result, the head can be easily and surely converged on the target track for stabilization.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic view of the essential parts of an embodiment of the present invention. FIG. 1A is a block diagram of a feed motor servo system in which a pickup, which is a head in an optical disc device such as a CD-ROM drive as shown in FIG. 2 described later, seeks a target track of a disc medium by a feed motor. Yes, FIG. 1 (B) is the MPU of FIG. 1 (A).
3 is a functional block diagram of FIG.

In FIG. 1A, M as a control means
A target address given to a PU (microprocessor unit) 31 from a host device (upper device such as a personal computer to which a disk device is connected) not shown, and a current address where the pickup is currently located,
A frequency-divided track jump pulse obtained by frequency-dividing (for example, 64 as will be described later) the track jump pulse read from the disk medium during movement of the pickup via the frequency divider 32 is input. The MPU 31 is connected so as to receive the reference clock generated by the clock generator 33, and is also connected to a ROM (Read Only Memory) 34.

The ROM 34 stores moving speed data according to the moving distance or moving amount of the pickup and data for applying a reverse drive brake to the feed motor. Therefore, the MPU 31 refers to the moving speed data from the ROM 34 on the basis of the current address or target address of the pickup, the divided track jump pulse, and the reference clock from the clock generator 33, and outputs the first control signal for initial control, Second control signal for deceleration control, third control for brake control
Is supplied to the feed motor servo circuit 35. Then, the feed motor servo circuit 35 is connected to the motor driver (D
-A converter and the like), and the feed motor 36 for moving the pickup is controlled and driven by the motor driver.

Further, in FIG. 1B, the MPU 31
Has a calculation function of the down counter 41, the up counter 42, the counter 43, and the counter 46, and the ROM 3
4 has a calculation function of a divider 44 and a multiplier 45 that calculates based on the data from the ROM 34a in a partial area,
The switch 47 has a conditional branch calculation function and the track number calculation circuit 48 has a calculation function. The divided track jump pulse from the frequency divider 32 is input to the down counter 41 and the up counter 42, and the down counter 41 down counts the number of track jumps given from the track number calculation circuit 48 with the divided track jump pulse. . This track jump number is calculated and obtained by the track number calculation circuit 48 from the target address given from the host device immediately before the seek operation and the current address where the pickup is currently located.

The counter 46 is activated by a seek start instruction coming from the host device and counts the reference clock of the clock generator 33, for example, 5 msec. While the counter 46 is measuring 5 msec, the switch 47 is controlled to output the data of the ROM 34c. The ROM 34c is the R of FIG.
Control data for driving the pickup at the maximum speed is stored in a part of the OM 34.

When the counter 46 finishes the measurement of 5 msec, the switch 47 causes the speed control amount from the ROM 34b in a partial area of the ROM 34c from the ROM 34c side and the counter 4 to operate.
It is switched to the adder 49 side for adding the brake control amount from No. 3 and outputs the speed control signal coming from the adder 49 to the feed motor servo circuit 35.

The output of the down counter 41 is to generate the data of the remaining track count number during the movement of the pickup when the speed control signal necessary for the deceleration control of the pickup is generated, and the pickup is set to the target position ( It is used to judge whether or not the vehicle has reached the stop start position).

To explain the operation, first, from the target address given from the host device immediately before the seek operation and the current address obtained from the pickup, the number of track jumps required for the pickup to move is calculated as a track number calculation circuit. It is calculated at 48 and given as an initial value of the down counter 41.

Next, when the seek operation is started, the down counter 41 counts down the number of track jumps by the divided track jump pulse. The count value at this time is given to the ROM 34b as address data. The ROM 34b is a partial area of the ROM 34 shown in FIG. 1A, and stores "remaining distance" data of the pickup and control amount data corresponding thereto in a table format. The control amount output from the ROM 34b is output as a speed control signal via the switch 47.
When the down counter 41 indicates count 0, a trigger pulse is output to the divider 44 to start the brake control.

On the other hand, the up counter 42 is always supplied with the reference clock of the clock generator 33, and is reset by the divided track jump pulse. That is, the time T between the incoming divided track jump pulses.
φ is measured and output to the divider 44.

The divider 44 starts the division for the first time by the trigger pulse of the down counter 41. Distance data for each track jump pulse, which is the moving speed information read from the ROM 34a (number of divided tracks K × track pitch T)
p) is divided by the time Tφ from the up counter 42 (K · Tp / Tφ) to obtain the pickup moving speed vφ immediately before the start of the brake control.

The immediately preceding velocity (vφ) is calculated by the multiplier 45,
The constant β read from the ROM 34a is multiplied (β · v
φ), this value is used as the brake signal application time by the counter 4
3 is output. The counter 43, like the counter 41, is a down counter, down counts the reference clock from the clock generator 33 after the data from the multiplier 45 is input, and sends it from the counter 43 until the count value becomes zero. Feed motor 36 to motor servo circuit 35
It outputs a brake control signal which is a third control signal for reversely rotating.

Here, FIG. 2 shows an overall configuration diagram of an example of a disk device to which FIG. 1 is applied. FIG. 2 shows the optical disk device 51, which is a CD-RO which is a disk medium.
An optical disk 52 such as M is rotatably mounted on a disk motor 53. A pickup 54, which is a head, is provided movably in the radial direction of the optical disc 52 by a feed motor 36, which is a moving means, via a lead screw 36a. The pickup 54 includes a laser diode 55, a beam splitter 56, and a light receiving section (detector) 5
7, the reflecting mirror 58 and the objective lens 59. The objective lens 59 is arranged in a suspended state by a wire or the like as described above, although not shown,
There are provided actuators for finely moving in the horizontal and vertical directions, respectively.

That is, the optical pickup 54 irradiates the optical disk 52 with the laser light emitted from the laser diode 55 through the beam splitter 56, the reflecting mirror 58, and the objective lens 59, and the reflected light from the optical disk 52 is the objective lens 59. The light is received by the light receiving unit 57 via the reflection mirror 58 and the beam splitter 56.

On the other hand, in the circuit system, there is provided a controller 61 as a system control unit for controlling the entire apparatus, and this controller 61 is provided with an MPU of the overall control system, and FIG. It is a diagram showing a configuration diagram of a motor servo system. This controller 61
Mainly controls the disk motor drive circuit 62, the focus servo circuit 63, the tracking servo circuit 64, the feed motor servo circuit 35, and the signal processing circuit 65. The controller 61 is connected to a host device such as a personal computer via an interface circuit or the like.

The disk motor drive circuit 62 drives the disk motor 53 based on a control signal from the controller 61 so that the optical disk 52 is rotated at a predetermined rotation speed. The focus servo circuit 63 drives the actuator of the pickup 54 according to a control signal from the controller 61 based on the detected focus error signal, and slightly moves the objective lens 59 in the direction of the optical disc 52 to perform focusing. Tracking servo circuit 64
Drives the actuator by a control signal from the controller 61 based on the detected tracking error (TE) signal, and minutely moves the objective lens 59 in the radial direction of the optical disc 52 to perform tracking.

The feed motor servo circuit 35 drives the feed motor 36 by the above-mentioned various control signals from the controller 61 based on the detected position error signal, track pulse, etc., and causes the pickup 54 to perform rough seek for movement between tracks. . The signal processing circuit 65 processes the information reproduced by the pickup 54 under the control of the controller 61. This reproduction information includes the track jump pulse read during the seek of the pickup 54, the number of track jumps is measured in the controller 61, and the track jump pulse is supplied to the frequency divider 32.

The essential parts of the mechanical structure of the optical disk device 51 are the same as those shown in FIGS. 6 and 7. Therefore,
FIG. 3 shows a principle explanatory diagram of the feed motor drive control of FIG. 3A is a waveform diagram of the control current, and FIG. 3B is a state diagram of the speed of the pickup 54. FIG. 3 (A),
In (B), at the start of seek t ₀ , the pickup 5
4 determines whether the number of tracks (or distance) to the movement target position (t ₂ ) is equal to or more than a predetermined value (N). When the number is equal to or more than the predetermined value, the MPU 31 causes the feed motor servo circuit 35 to
A control signal for rotating the feed motor 36 at the maximum rated output (first control signal for initial control) is supplied to rotate the feed motor 36 to move the pickup 54.
At this time, the speed of the pickup 54 gradually increases from the start of the movement, and becomes a steady movement state when reaching a constant speed. During the movement of the pickup 54, the number of remaining moving tracks (or distance) is calculated from the number of track jumps.

When the number of remaining moving tracks (or distance) becomes equal to or less than the predetermined value (N) (t ₁ ), the down counter 41 and the up counter 42 shown in FIG. Start counting by jump number and reference clock, and ROM in divider 44
The moving speed is calculated based on the moving speed information from 34, and the speed control signal as the second control signal for the deceleration control is supplied to the feed motor servo circuit 35 to enter the deceleration state.

In this deceleration state, the MPU 31 gradually decelerates based on the moving speed information of the ROM 34 until the pickup 54 reaches the target position (t ₂ ) (T ₁ ).
A control signal is supplied to the feed motor servo circuit 35. Even when the pickup 54 reaches the target position (t ₂ ), the inertia of the feed motor 36 keeps rotating in the feed direction at a predetermined speed. Therefore, the speed immediately before is shown in Figure 1.
It is calculated in the multiplier 45 shown in (B) based on the information from the ROM 34, and the time (T ₂ = t) corresponding to this speed is calculated.
Feed motor servo circuit 3 from MPU31 during _3- t ₂ )
5 is supplied with a brake control signal as a third control signal for performing brake control for causing the feed motor 36 to rotate in the reverse direction at the maximum rated output. The brake control signal is supplied so that the pickup 54 is stopped at the target track position (t ₃ ) and the speed of the pickup 54 becomes zero.

As a result, the pickup 54 is immediately positioned (converged) on the target track. That is, the pickup 54 can be converged to the target track stably with a small error by the open loop control method, and since it is converged immediately, the time until convergence is shortened and the seek and the access are speeded up. Is.

[0038]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In an optical disk device 51 using the above-mentioned CD-ROM as a disk medium (optical disk 52), the objective lens 59 of the pickup 54 is a wire (spring) as described above.
When the actuator is used for focusing and tracking, the manufacturing cost is low, but the objective lens 59 is applied against the force (acceleration) in the disk radial direction generated during seek or tracking. Will be twisted. For example, if a strong acceleration is applied to the pickup 54 at the time of seek, the objective lens 59 collides with the inner wall and adversely affects the tracking operation immediately after the seek is completed.

Therefore, the maximum twist amount allowed for the objective lens 59 is determined, and the maximum acceleration allowed for the pickup 54 is calculated using the spring constant of the wire supporting the objective lens 59. Here, the maximum twist amount is 50
Set to μm and set the maximum allowable acceleration to 2.4 m / sec ² .

Here, FIG. 4 shows an explanatory view of an example of the control amount of the feed motor of the present invention. As described above, the maximum twist amount of the objective lens is 50 μm and the maximum allowable acceleration is 2.4 m / sec ²
At this time, the moving speed information stored in the ROM 34 is set as shown in FIG. Note that the control amount D _C in FIG. 4 shows the case of decimal and hexadecimal, and the parameter of the speed of the pickup 54 with respect to a predetermined count value N corresponding to the number of remaining tracks (or distance) in the movement is stored as a table. It In this case, the count value N is the number of frequency-divided track jump pulses, as will be described later, and is to shift to the deceleration state from N ≦ 46.
When N> 46, the feed motor 36 is moved at a speed according to the maximum rated output.

The speed setting in the ROM 34 will be described. First, the maximum permissible speed (maximum rated output) v _max of the feed motor 36 is set to 0.15 m / sec due to the restriction of the motor driver included in the feed motor servo circuit 35, and the deceleration α is equal to the maximum permissible acceleration α = 2.4 m. / sec ²
And An optical disc (CD-
The track pitch T _P of the ROM) 52 is 1.6 μm.
Due to the processing capability of the MPU 31, the frequency of the track jump pulse is divided by the frequency divider 33 (frequency division ratio K = 64) and one pulse is moved every 64 tracks to move the MPU 31 (the down counter 41 and the up counter 42). ). In this case, the operating characteristics of the feed motor 36 increase linearly with respect to the current.

Therefore, focusing on the moving distance of the pickup 54, the number of divided pulses generated in the deceleration region is obtained. Since the velocity v is v = α · t, the distance L is L = (α / 2) t ² = (α / 2) × (v / α) ² = v ² / 2α (1) Become. If the number of divided track counts is N, L = T
_{From P} KN, T _P KN = v ² / 2α N = v ² / (2 · α · T _P · K) (2) Therefore, substituting a numerical value results in N = 46 counts. That is, the deceleration state is shifted from N = 46.

[0043] The speed v from the equation (2), v = a _{√ (2 · α · T P} · K · N) ··· (3), the speed is v = 22.2 × 10 ^-3 √N ( m / sec). Further, the control amount D output to the DA converter in the motor driver included in the feed motor servo circuit 35
_{When C} has a resolution of 256, D _C = (v / v _max ) × 256 × √N = 37.8√N (4) Therefore, the speed v and the control amount D _C when the divided track count number N is sequentially decreased by one from 46 are as shown in FIG.

Next, FIG. 5 shows a current waveform diagram of the feed motor drive control according to the seek distance of the pickup. In FIG. 5A, at the seek start time t ₀ , an initial control signal for rotating the feed motor 36 at the maximum rated output (maximum allowable speed v _max ) for a period of, for example, 5 msec is output with the period of T _{0 being} a fixed period. . 5 msec later, it is judged whether or not the moving distance T ₁ from the position (t ₀₁ ) of the pickup 54 to the target position (t ₂ ) is N> 46, and FIG.
In the case of N> 46, as shown, the maximum allowable speed v _max
It is moved as it is until N = 46 (T ₁₁ ).

At the time when N = 46 (t ₁ ) due to the movement of the pickup 54, the speed is sequentially decelerated according to the count value of N at the speed v stored in the ROM 34 (T ₁₂ ). Then, when v = 0 (t ₂ ) is the target position, the supply time T ₂ of the brake control signal is calculated from the speed immediately before that, as shown in FIG.
The brake control signal for rotating the feed motor 36 in the reverse direction is supplied as shown in (1) to position the pickup 54 on the target track.

On the other hand, as shown in FIG. 5B, T ₀ (5
When the remaining movement amount after the movement of the maximum allowable speed v _max of (msec) (t ₁ ) is (N ≦ 46), the speed corresponding to the N value is read from the ROM 34 and the target position t ₂ (T ₁ ) Slow down to. Then, the supply time T ₂ of the brake control signal is calculated from the speed immediately before N = 0 (t ₂ ) as shown in FIG. 1B, and the brake control signal for rotating the feed motor 36 in the reverse direction is supplied. The pickup 54 is positioned on the target track.

In this way, the speed to be stored in the ROM 34 is obtained in advance, and the feed motor 36 is moved at the maximum speed by the maximum control amount of the motor driver (feed motor servo circuit). Nevertheless, the pickup 54 can be converged at high speed to achieve high speed and stability.

In the above embodiments, the optical disk device is shown as an example, but the present invention can be applied to all disk devices that seek heads such as pickups by the open loop control system.

[0049]

As described above, according to the first aspect of the present invention,
The control means, based on the track information by the head movement,
A first control signal is supplied at the start of movement, a second control signal is supplied when the head moves to a predetermined position and decelerated based on the moving speed information from the storage means, and the supply of the second control signal is stopped. By supplying a third control signal for driving the moving means in the reverse direction for a predetermined period later, the head can be stably converged on the target track without overshooting despite the open loop control method. The time until convergence can be shortened, and seek and access can be speeded up.

According to the second aspect of the invention, the moving means is driven so as to reach the maximum rated output by supplying the first control signal at the start of driving the moving means and the third control signal for driving the moving means in the reverse direction. By doing so, the speed can be increased by shortening the time until the head converges on the target track.

According to the invention of claim 3, the supply time of the third control signal is obtained by multiplying the moving speed of the head immediately before the stop of the second control signal by a preset constant. Thus, the head can be easily and surely converged on the target track for stabilization.

[Brief description of the drawings]

FIG. 1 is a main part configuration diagram of an embodiment of the present invention.

FIG. 2 is an overall configuration diagram of an example of a disk device to which FIG. 1 is applied.

FIG. 3 is a diagram illustrating the principle of drive motor drive control of FIG.

FIG. 4 is an explanatory diagram showing an example of a control amount of the feed motor of the present invention.

FIG. 5 is a current waveform chart of the feed motor drive control according to the seek distance of the pickup.

FIG. 6 is a plan view of a main part of an example of a conventional disk device (1)
It is.

FIG. 7 is a plan view of an essential part below the pickup mechanism of FIG.

FIG. 8 is an explanatory diagram of a feed motor drive control of a conventional disk device.

[Explanation of symbols]

 31 MPU 32 Frequency divider 33 Clock generator 34 ROM 35 Feed motor servo circuit 36 Feed motor 41 Down counter 42 Up counter 43 Counter 44 Divider 45 Multiplier 51 Optical disk device 54 Pickup

Claims (3)

[Claims] 1. A disk device having a function of controlling the position of a head moved by a moving means to a target track of a storage medium by an open-loop system and moving the head, wherein the head moves with respect to a moving amount of the head in a predetermined section. Storage means for storing movement speed information in advance, and information regarding movement of the head based on track information read when the head is moved, and the storage means at the start of movement according to the movement amount of the head. A first control signal for initial control to be output to the moving means based on the moving speed information from the head, and the arrival of the head on the target track based on the moving speed information from the storage means according to the position of the head. A second control signal for decelerating a predetermined movement period until immediately before the start of braking, and a movement means for a predetermined period after the supply of the second control signal is stopped is reversed. The to direction drive 3
And a control means for supplying the control signal of 1) to position the head on the target track. 2. A disk device, wherein the first and third control signals supplied by the control means according to claim 1 are signals which should drive the moving means to a maximum rated output. 3. The third control signal supplied from the control means according to claim 1 corresponds to the moving speed of the head immediately before the stop of the second control signal stored in the storage means. The disk device is characterized in that it is supplied in a time obtained by multiplying by a constant.