JP2545618B2 - Track jump control device for optical disk device - Google Patents

Description

The present invention relates to a track jump control device for an optical disk device that moves a light beam from an optical head to a target track position by controlling the speed of a track actuator, and a deceleration for stabilizing the beam settling after the end of the track jump. For the purpose of control, the speed of the track actuator is controlled based on the speed error between the target speed and the beam moving speed, and during deceleration control at the end of the tra-jump, the deceleration time and the deceleration time are calculated based on the beam moving speed detected immediately before the target track. The deceleration control is performed by calculating the deceleration start timing at which the deceleration is finished at the center of the target track and the speed becomes zero.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a track jump control device for an optical disk device that moves a light beam from an optical head to a target track position by controlling the speed of a track actuator.

The optical disk device has a large storage capacity because the track interval can be set on the order of several microns, and has recently attracted attention as a large-capacity storage device for computer systems and the like.

The optical disc drive track jump control is to move a light beam from an optical head to a target track position designated by external read access or write access by speed control.

That is, the speed of the track actuator is controlled based on the speed error between the target speed and the beam moving speed detected from the tracking error signal with the track servo off, and the acceleration pulse voltage is applied to the actuator at the start of the track jump. Acceleration control is performed, and deceleration control is performed by adding a deceleration pulse voltage at the end of the track jump.

However, the beam moving speed before entering the deceleration control performed immediately before the end of the track jump does not always completely match the target speed, and usually has a velocity control residual, and the deceleration control is performed for a certain period of time. However, the beam velocity is not completely zero, and the beam settling becomes unstable after jumping into the track servo at the end of the track jump. Therefore, in order to completely reduce the beam speed to zero during the deceleration time, the deceleration time may be set according to the beam speed at the start of deceleration control. However, with such a setting of the deceleration time, the beam deviates from the center of the target track at the end of deceleration, and therefore control is desired to end deceleration at the track center.

[Prior Art] FIG. 6 is an explanatory view of a conventional device.

In FIG. 6, for example, 36
An optical head 12 is provided so as to be freely movable in the radial direction by a head drive motor 26 with respect to the optical disk 10 which is rotated at a constant speed of 00 rpm. Done.

A semiconductor laser 28 as a light source is provided in the optical head 12, and the light from the semiconductor laser 28 is collimated by a collimator lens.
The beam is guided to the objective lens 36 through the polarization beam splitter 32, the λ / 4 plate 34, the beam spot is narrowed down by the objective lens 36, and the optical disc 10 is irradiated with the beam spot. The beam reflected light from the optical disk 10 is reflected at right angles by the polarization beam splitter 32 and enters the four-divided light receiver 40 via the condenser lens.

In such an optical disk device, the optical disk 10
A large number of tracks are formed in the radial direction at an interval of, for example, a track pitch of 1.6 μm. Even a slight eccentricity greatly shifts the track position, and the waviness of the optical disk shifts the focus position of the beam spot. It is necessary to follow the beam spot of 1 μm or less.

Therefore, a focus actuator 42 that moves the objective lens 36 of the optical head 12 in the vertical direction to adjust the focal position.
And a track actuator 44 for moving the objective lens 20 in a direction transverse to the track and following the beam to the track.
And are provided.

The focus actuator 42 is the focus servo circuit
Controlled by 46. That is, the focus servo circuit 46
Drives the focus actuator 42 so that the focus error signal FES obtained from the light receiving signal of the four-division light receiver 40 is minimized.

The track actuator 44 is a track servo circuit 48 during a track servo for making a beam follow a target track.
On the other hand, the speed is controlled by the speed control circuit 50 at the time of a track jump for moving the beam to an arbitrary track for new access.

FIG. 7 is an explanatory view of the conventional track jump control. In order to make the beam jump from the initial position S to the target track position, the track actuator is designed to minimize the speed error Ve between the target speed Vt and the beam moving speed V. The speed control for feedback control is performed. At the same time, at the start of a track jump, an acceleration pulse of an acceleration voltage + Va is applied for a certain period of time to control the acceleration of the track actuator to quickly reach the target speed. Thus, the track actuator can be decelerated and controlled to reach the target track position with the beam velocity set to zero, and jump into the track servo control.

However, in the conventional track jump control, there is a problem that the beam velocity is not completely zero even after the deceleration control is completed, and the beam settling after the track servo jump becomes unstable.

That is, as shown in FIG. 8 (a), when the beam moving speed V at the time of deceleration start at time t1 coincides with the target speed Vt and there is no residual speed control, a constant deceleration time equal to the acceleration time is used. T
The beam velocity V becomes completely zero by the deceleration control over, and the beam is settled stably after the track servo jump.

However, as shown in FIGS. 8B and 8C, the beam moving speed V at the start of the deceleration control at the time t1 is equal to the target speed Vt.
Larger or smaller speed control residual + V
In the case where e and −Ve have occurred, even when deceleration control is performed for a fixed deceleration time T, the speed at the time of track servo diving does not become zero, and beam setting after track servo diving becomes unstable, There is a problem that the waiting time until the read / write is enabled becomes long.

To solve this problem, as shown in FIG. 9, if the deceleration time is calculated and controlled according to the beam moving speed V at the start of deceleration control, the beam speed can be surely made zero at the end of deceleration. .

It should be noted that FIG. 9 shows a beam speed V1 equal to the target speed Vt, a high beam speed V2, and a low beam speed at the deceleration start time t1.
The deceleration times T1, T2, and T3 in three cases of V3 are shown.

[Problem to be Solved by the Invention] However, when the deceleration pulse is output for the deceleration time calculated according to the beam velocity, the place where the deceleration ends is changed. For example, when the beam speed is appropriate, deceleration can be completed at the center of the target track as shown in FIG. 10 (a), but when the beam speed is slow, FIG. 10 (b) As shown in, the short deceleration time is calculated, the deceleration ends before the center of the target track, undershoot occurs until the track servo is switched to the track center, and beam establishment becomes unstable. There was a problem. When the beam speed is high, there is a problem that the deceleration time becomes long and the beam overshoots the track center at the end of deceleration to cause overshoot.

The present invention has been made in view of the above conventional problems, and an object of the present invention is to provide a track jump control circuit of an optical disk device that performs deceleration control so as to stabilize beam establishment after the end of a track jump. .

[Means for Solving the Problems] FIG. 1 is a diagram illustrating the principle of the present invention.

In FIG. 1, an optical head 12 for recording and reproducing information on a track of a medium 10 rotated at a constant speed is provided, and a track actuator 14 for moving a light beam in a direction crossing the medium track is mounted on the optical head 12. Is done.

At the time of a track jump, the track actuator 14 is controlled by the speed control means 16. That is, speed control means
Reference numeral 16 generates a target velocity Vt at the time of a track jump and detects the beam moving velocity V based on a tracking error signal obtained from the light receiving signal of the optical head 12 to obtain a velocity error Ve of the beam moving velocity V with respect to the target velocity Vt. The speed is detected and the speed of the track actuator 14 is controlled so as to minimize the speed error Ve.

Further, an acceleration means 18 for controlling the acceleration of the track actuator 14 at the start of the track jump and a deceleration means 20 for controlling the deceleration of the track actuator 14 at the end of the track jump are provided.

Further, in the present invention, the deceleration means 20 includes a deceleration time calculation unit 22 for calculating the deceleration time T based on the beam moving speed V immediately before the target track, and a beam speed when the beam reaches the center of the target track. And a deceleration timing calculation unit 24 for calculating the timing for starting the deceleration control over the deceleration time T calculated by the deceleration time calculation unit 22 so that 0 becomes zero.

Here, the deceleration timing calculation unit 22 calculates the loss time (T) loss from the center of the target track to the start of deceleration starting 1 track pitch before or half track pitch before.

In addition, the deceleration timing calculation unit 22 calculates the product V · (T) loss of the loss time t and the beam velocity, the beam velocity V, and the deceleration time T.
The loss time so that the sum of the product and the product of the track pitch Tp or 1/2 track pitch, Tp = V · (T) loss + VT / 2 or Tp / 2 = V · (T) loss + VT / 2 holds. Calculate (T) loss.

 That is, the loss time (T) loss is calculated as (T) loss = (Tp / V)-(T / 2).

Further, the speed control means 16 uses the tracking error signal TE
The beam moving speed is detected based on the zero-cross period of S.

[Operation] According to the track jump control circuit of the present invention having such a configuration, even if there is a velocity control residual in the beam movement velocity at the start of deceleration, it is possible to respond to the beam movement velocity having the velocity control residual. The deceleration time is calculated, and the deceleration start timing is controlled so as to end the deceleration at the center of the target track, so that the beam settling after jumping into the track servo can be stabilized and the access time can be shortened.

[Embodiment] FIG. 2 is a configuration diagram of an embodiment showing one embodiment of the present invention.

In FIG. 2, reference numeral 12 is an optical head, and as shown in FIG. 6, a track actuator 14 for moving the beam spot on the optical disk in the direction traversing the track.
And a four-division light receiver 40 for receiving the return light from the optical disk. The four light reception signals from the four-division light receiver 40 are input to the RF generation circuit 52, and the high frequency reproduction signal RFS is obtained by calculating the sum of the four light reception signals, and the high frequency reproduction signal RFS is given to the MPU 100 to obtain the reproduction signals. .

The output of the four-division light receiver 40 is input to the tracking error detection circuit 54 provided in the control circuit section 200. The tracking error detection circuit 54 detects the tracking error signal TES by subtracting the added light receiving signals of the light receiving units B and C from the added light receiving signals of the light receiving units A and D, that is, (A + D)-(B + C). The tracking error signal TES is subjected to lead phase compensation for raising the high frequency band of the servo band by the phase compensation circuit 56. The tracking error signal TES from the phase compensation circuit 56 is input to the power amplifier 62 via the switch 58 for turning the track servo on and off, and the adder 60. The power amplifier 62 current-drives the tracking coil of the track actuator 14 based on the tracking error signal TES.

In this embodiment, the speed control circuit for performing the track jump control on the track servo circuit provided in the control circuit unit 200 is realized by the program control of the MPU 100 in this embodiment.

That is, the MPU 100 is provided with a target velocity generating unit 68, a beam velocity detecting unit 70, a velocity error detecting unit 72, and further an accelerating unit 18 and a decelerating unit 20 for performing velocity control. Further, in connection with speed control, the control circuit unit 200 has a zero-cross comparator for detecting the zero-cross timing of the tracking error signal TES.
DA converter 66 that converts the speed control data calculated on the MPU100 side into an analog signal voltage and adds it from the adder 60
Is provided.

The speed control for the track jump realized by the MPU100 is such that when the track jump is instructed to the MPU100, the target speed generation unit 68 sets a constant target speed Vt or the remaining number of tracks (access difference) to the target track. The target velocity Vt is generated, and the velocity error Ve with respect to the beam velocity V detected by the beam velocity detector 70 is calculated by the velocity error detector 72. This velocity error Ve is set in the DA converter 66, and the adder 60 The speed error voltage is output to. Beam velocity detector 70
The velocity is detected by the timer by counting the zero-cross output cycle of the tracking error signal TES from the zero-cross comparator 64, for example, the rising cycle to the H level, and this rising cycle is the beam passing time of the track pitch Tp. The beam velocity V can be obtained by dividing the track pitch Tp by the rising cycle of. The track pitch Tp is Tp = 1.6 μm in the case of an ISG standard 5-inch optical disc, for example.

Further, the acceleration unit 18 sets the acceleration data in the DA converter 66 at the start of the track jump control, and outputs the acceleration voltage + Va from the adder 60 over the acceleration time. Also the reduction unit
20 sets the deceleration data in the DA converter 66 at the end of the track jump, and outputs the deceleration voltage −Va from the adder 60 over the deceleration time T.

Here, the deceleration unit 20 calculates the deceleration time T based on the beam velocity V at the end of the track jump, and the deceleration time calculation unit 22 that terminates the deceleration when the beam reaches the center of the target track by deceleration control. Further, a deceleration timing calculation unit 24 for calculating the start timing of deceleration control according to the deceleration time T is provided.

More specifically, the deceleration time calculation unit 22 uses the beam speed V obtained at the zero cross timing of the tracking error signal TES one track before the target track, and calculates the deceleration time T by the following equation. .

T = C × V (1) (where C is a constant and is given as the reciprocal of the deceleration acceleration due to the deceleration voltage −Va.) On the other hand, the deceleration timing calculation unit 24 calculates the deceleration time calculated by the deceleration time calculation unit 22. Based on T, the beam velocity V, and the track pitch Tp, the loss time (T) loss from the zero cross timing one track before the target track to the start of deceleration control is calculated.

FIG. 3 is a diagram illustrating the principle of deceleration control according to the present invention,
FIG. 3 (a) shows a low speed, and FIG. 3 (b) shows a high speed.

For example, when the beam velocity at time t1 immediately before the target track where the tracking error signal TES is zero crossing is V1 at the low speed in FIG. 3 (a), the deceleration time T1 is T1 = C.multidot.C from the equation (1). Required as V1. In order to end the deceleration control at the center of the target track at the time t3 by the deceleration over the deceleration time T1, the loss time (T) loss from the time t1 to the time t2 when the deceleration control is started is required.

Here, the track pitch Tp, which is the moving distance from time t1 to t3, is given by the area shown by the shaded portion of the speed control from time t1 to t3. That is, when it is generalized and expressed as V1 = V and T1 = T, Tp = (V × Tloss) + (V × T) / 2 (1) holds. Therefore, the loss time (T) loss is calculated as (T) loss = (Tp / V)-(T / 2) (2).

The area of the speed control indicated by the shaded portion at low speed shown in FIG. 3 (a) is the area of the shaded portion of the speed control of loss time and deceleration control at times t1 to t3 at the time of high speed shown in FIG. 3 (b). Matches

That is, according to the present invention, even if the beam velocity V obtained at the zero cross of the tracking error signal TES before the target track is 1 track pitch Tp is different, the deceleration time based on the loss time (T) loss and the beam velocity V. By obtaining the loss time (T) loss so that the area of the speed control given by T matches the track pitch Tp, the deceleration control that always ends the deceleration at the center of the target track can be performed.

Next, the track jump control of the present invention will be described with reference to the operation flow chart of FIG.

When a track jump is instructed to the MPU100 by the host device, first, step S1 (hereinafter, step is omitted).
At, the access difference, that is, the remaining number of tracks D from the current position to the target track is set to D = D-2. As shown in the track jump explanatory diagram of FIG. 5, one track at the start of the track jump is assigned to acceleration control, one track at the end of the track jump is assigned to deceleration control, and the track remaining except for two tracks is left. Since the speed control is performed for a number, a value obtained by subtracting 2 from the set track difference D is set.

Then, in S2, the track servo is turned off. That is, the switch 58 of the control circuit unit 200 is turned off. Subsequently, in S3, the acceleration voltage + Va is set in the DA converter 66, and acceleration control is started. The acceleration time is monitored by S4, and when the acceleration time elapses, the set voltage of the DA converter 66 is returned to 0 volt,
The acceleration control is ended, and then the target speed Vt for speed control is prepared.

Then, in S6, the timer is reset to 0, and S7 and
The process proceeds to S8, and the output TZC of the zero cross comparator 64 detects the zero cross of the tracking error signal TES. When the zero cross is detected, the process proceeds to S9 to start the timer, and the next S10 and S11 detect the zero cross of the next tracking error signal, specifically, the rising timing of the zero cross comparator output TZC shown in FIG. S1
When the zero cross of the tracking error signal TES is detected from 0 and S11, the process proceeds to S12, and the timer is stopped. At this time, the timer obtains the count value indicating the rising cycle of the zero cross comparator TZC.

Then, the process proceeds to S13, and the beam velocity V is calculated from the timer count obtained in S12, that is, the zero-cross cycle and the track pitch Tp. Subsequently, the beam velocity V is subtracted from the target velocity Vt in S14 to calculate the velocity error Ve, the velocity error is set in the DA converter 66 in S15, and the velocity error voltage Ve is supplied to the track actuator 14 to maintain the target velocity Vt. Feedback control.

Then, since one track pitch was passed in S16, one access difference D is subtracted and the next
If the track difference does not reach 0 in S17, S
Proceeding to 18, after setting the predetermined loss time determined by the program step in the timer, the process returns to S9 again, and the same speed control is repeated.

When the access difference D = 0 in S17, that is, when the zero cross timing one track pitch before the target track center is reached, the process proceeds to S19, in which the deceleration time T is calculated based on the equation (1). Then, in S20, the loss time (T) loss is calculated based on the equation (2). Then, in S21, the loss time (T) loss is set in the timer, and in S22, the loss time (T) loss is set. When the timer expires, the process proceeds to S23, where the deceleration voltage −Va is set to DA.
Set it in the converter 66 and start deceleration control. The deceleration control time T is monitored in S24. When the deceleration time T elapses, the process proceeds to S25 to set the DA converter 66 to zero voltage,
As a result, the track servo is turned on since the track jump is completed, and a series of track jump control is completed after waiting a predetermined set time in S26. As a result,
Beam deceleration control based on the deceleration time T calculated based on the beam speed V at the time when the loss time (T) loss has elapsed from the rising timing of the zero-cross comparator output one track pitch before the target track center in FIG. The beam reaches the target track center when the deceleration control is completed and the beam speed becomes zero.At this time, the track servo is turned on to make the beam establishment stable and secure. The beam can follow the target track and the read or write operation is immediately enabled.

In the above embodiment, the deceleration time T and the loss time (T) loss are calculated from the beam speed obtained at the zero cross timing of the tracking error signal one track pitch Tp before the center of the target track. The deceleration time T and the loss time (T) loss may be similarly obtained from the beam velocity V obtained at the zero-cross timing half track pitch Tp / 2 before the center to perform deceleration control. In this case, the track time Tp in the equation (2) is set to Tp / 2 and the loss time (T) loss is set.
Should be calculated.

As described above, according to the present invention, even if there is a velocity control residual in the beam velocity at the end of the track jump,
Calculation of deceleration time according to beam speed and deceleration start timing are controlled so that deceleration ends at the center of the target track, the stability of beam settling when jumping into the track servo is improved, and access time can be shortened. As a result, the seek error rate can be greatly improved.

[Brief description of drawings]

FIG. 1 is a diagram for explaining the principle of the present invention; FIG. 2 is a configuration diagram for an embodiment of the present invention; FIG. 3 is an explanatory diagram for deceleration control according to the present invention; FIG. 4 is an operation flow diagram for the present invention; FIG. 6 is an explanatory view of a conventional device; FIG. 7 is an explanatory view of a conventional track jump; FIG. 8 is an explanatory view of a conventional deceleration control; Explanatory diagram of deceleration time; FIG. 10 is an explanatory diagram when the deceleration time is changed according to the final beam velocity. In the figure, 10: medium (optical disk) 12: optical head 14: track actuator 16: speed control means 18: acceleration means 20: deceleration means 22: deceleration time calculation unit 24: deceleration timing calculation unit 40: 4-division receiver 52: RF creation circuit 54: Tracking error detection circuit 56: Phase compensation circuit 58: Switch 60: Adder 62: Power amplifier 66: DA converter 68: Target speed generator 70: Beam speed detector 72: Speed error detector 100: MPU 200: Control circuit section

Claims (5)

(57) [Claims] 1. An optical head (12) for recording / reproducing information on / from a track of a medium (10) which is rotated; and a direction of a light beam from the optical head (12) crossing a track of the medium (10). A track actuator (14) which is moved to a position; a target velocity (Vt) is generated at the time of a track jump, and a beam moving velocity (V) is detected based on a tracking error signal obtained from a light receiving signal of the optical head (12). ,
A velocity control means (16) for detecting a velocity error (Ve) of the beam moving velocity (V) with respect to the target velocity (Vt) and controlling the velocity of the track actuator (14) so as to minimize the velocity error (Ve). ); And a deceleration means (20) for decelerating and controlling the track actuator (14) at the end of the track jump, and further comprising: the deceleration means (20) for adjusting the beam moving speed (V) immediately before the target track. Deceleration time calculation unit (22) that calculates deceleration time (T) based on
Deceleration timing for deriving the timing for starting deceleration control over the deceleration time (T) derived by the deceleration time calculation unit (22) so that the beam velocity becomes zero when the beam reaches the center of the target track. A track jump control device for an optical disk device, which is provided with a calculating section (24); 2. The optical disc according to claim 1, wherein the deceleration timing calculation unit (22) derives a loss time (T) loss from the center of the target track to the start of deceleration starting one track pitch before. Equipment track jump controller. 3. The deceleration timing calculation unit (22) derives a loss time (T) loss from the center of the target track to a point before the half track pitch before starting the deceleration control (T) loss. A track jump control device for the optical disk device described. 4. The deceleration timing calculation unit (24) is a product of loss time (T) loss and beam velocity (V) V · (T) lo.
Half of the product of ss, beam velocity (V) and deceleration time (T) (VT
The loss time (T) loss is derived so that a relational expression in which the sum of / 2) is equal to the one track pitch (Tp) or the half track pitch (Tp / 2) is established. Track jump control device of the optical disc device. 5. The optical disk apparatus according to claim 1, wherein the speed control means (16) detects the beam moving speed (V) based on the zero-cross cycle of the tracking error signal obtained during the track jump. Track jump controller.