JPH07182662A - Optical disc apparatus - Google Patents

Abstract

PURPOSE:To obtain an optical disc apparatus which can shorten retraction time before the focus control becomes normal at a target track as compared with a conventionally required time and improve accessing accuracy while restricting manufacturing costs. CONSTITUTION:At a jumping time over a track, a driving signal from a driving circuit 4 for driving an optical pickup part is fed to a rack and pinion part 2a with the use of a tracking error signal detected from an optical disc 1, thereby moving the optical pickup by a feed mechanism 2 in a diametrical direction of the optical disc l. A microcomputer 6 controls a biaxial actuator- driving part 5 so that a control pulse is output when the movement is started and ended. In consequence of this, an objective lens 3b is always arranged at a predetermined position by a driving signal of the driving part 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk device for jumping a plurality of tracks on an optical disk to access a target track by an optical pickup section for recording and / or reproducing.

[0002]

2. Description of the Related Art An optical disk device records an information signal by using light irradiated on an optical disk which is a disk-shaped recording medium, and reproduces an information signal recorded by the light irradiated on the disk-shaped recording medium. It is something to do. In this optical disc device, the optical pickup unit is roughly moved by a feeding mechanism that moves the optical pickup unit in the radial direction of the optical disc.

The optical system of the optical pickup unit and the objective lens are arranged in the optical pickup unit via an elastic member. This objective lens is finely adjusted by focus control in the focus direction of the objective lens by a biaxial actuator and tracking control in the track direction of the optical disc. Further, the optical disc device is provided with a drive circuit for moving the biaxial actuator in the radial direction of the optical disc. The amount of radial movement by the biaxial actuator according to the drive signal output from this drive circuit is calculated by counting the number of tracks that the light beam spot from the optical pickup unit has traversed with a counter and converting from the counted value. Is required. The optical disc device controls the track jump so that the optical pickup reaches the target track by the movement amount calculated in this way. The track jump in this optical disk device is generally performed within at most several hundred tracks. When performing this track jump, the optical disc apparatus is accessing with the tracking control turned off.

[0004]

By the way, as described above, the optical pickup section has a structure in which the objective lens and the optical system are connected by an elastic member. When performing tracking jump with the tracking control of this optical pickup unit turned off, the feed mechanism of the optical pickup unit that converts the rotation of the sled motor into the movement of the optical disc in the radial direction allows the optical pickup unit to move at high speed to the target track position. Access is possible. Further, recently, in a large-capacity optical disc that is handled as a data storage using the optical disc format for music, high-speed access of such an optical pickup unit has been further required.

When the optical pickup section is accessed at a high speed, the optical system fixedly arranged on the housing inside the optical pickup section is operated integrally with the feeding movement by the feeding mechanism of the optical pickup section. .

However, when the optical system is moved by the feeding mechanism of the optical pickup section, the inertia due to high-speed access acts on the objective lens greatly. By using the elastic member as a connecting member for supporting and arranging the objective lens at a predetermined position, as a result, the objective lens disposed above the optical system is left behind (see FIG. 4 (a)). In an extreme case, the objective lens of the optical pickup unit mechanically collides with the wall surface of the housing of the optical pickup unit in the position opposite to the arrow B in FIG.

This inertia also acts at the time of stop. That is, the objective lens that follows with a delay collides with the wall surface in the moving direction due to the inertia acting so as to maintain the moving speed (see FIG. 4B).

As described above, even if the optical pickup unit is moved at a high speed to access the target track, it may take a long time for the focus control to become possible again. Therefore, it takes time to restart the operation of the optical pickup unit at the target track position.

In order to solve this problem, conventionally, for example, as shown in FIG. 5, a light emitting diode 21 is arranged on a side surface 22 as a position sensor on a biaxial actuator 20 in an optical pickup portion, and a side wall of a housing facing the side surface 22. The position of the objective lens 24 with respect to the reference position b _a is detected by _a configuration in which the light receiving elements 25 are arranged in a line in 23 with the middle point position of the objective lens 24 as a reference, and the deviation from the midpoint position of the objective lens 24 is corrected. It has feedback control. However, such a position sensor must be added to the optical pickup section as a new constituent member, which is one of the causes for increasing the manufacturing cost.

Therefore, the present invention has been made in view of the above-mentioned circumstances, and while suppressing the manufacturing cost,
An object of the present invention is to provide an optical disk device capable of shortening the pull-in time until the focus control on the target track becomes normal and shortening the time required conventionally and improving the access accuracy.

[0011]

In order to solve the above-mentioned problems, an optical disk apparatus according to the present invention provides an actuator for controlling an objective lens in the optical axis direction and the track direction, information of a disk-shaped recording medium, and a servo error signal. An optical pickup unit composed of an optical unit for detecting, a feeding mechanism for moving the optical pickup unit in the radial direction of the disk-shaped recording medium, and an objective lens arranged in the optical pickup unit via an elastic member. When the optical pickup unit is moved to the target track by the feed mechanism by turning off the tracking control by turning off the tracking control, the objective lens is moved in the moving direction by the driving unit at the same time when the movement is started. The objective lens is driven by the driving means in the opposite direction to the moving direction at the same time as the movement is completed. It is characterized by having a that control means.

Here, the objective lens is movable in the optical axis direction of the objective lens by a biaxial actuator to perform focus control, and while performing the focus control, tracking control is performed in the track direction of the disc-shaped recording medium. It is characterized by fine adjustment. During the track jump, the objective lens is controlled to move while the focus control is being performed and the tracking control is turned off so that the optical pickup unit jumps to the target track.

[0013]

In the optical disk device according to the present invention, the optical pickup unit is driven by the driving means in the moving direction at the same time as the movement of the optical pickup unit by the feeding mechanism starts, so that the objective lens is not left behind due to inertia. The optical pickup unit is moved so as not to go over the target track of the objective lens by accelerating the moving speed for a certain period and driving the objective lens in the opposite direction to the moving direction by the driving means at the same time as the movement is finished. The speed is reduced for a certain period of time to avoid the collision of the objective lens in the housing of the optical pickup unit, while improving the accuracy of access to the target track and shortening the access time.

Here, as the jump amount to the target track in the optical disk device, a track jump of 1000 tracks or more is particularly assumed. In other words,
When the track pitch is, for example, 1.6 μm, the movement of 1000 tracks is about 1.6 mm. The present invention uses this 1.6 mm
It is effective when jumping the distance. Furthermore, the present invention is particularly effective when the optical pickup unit is 5 m.
This is effective when moving a distance of m or more.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an optical disk device according to the present invention will be described below with reference to the drawings. The present embodiment is an example applied to a case where an optical pickup unit in an optical disc device is track-jumped over a large distance.

In the optical disk device of this embodiment, for example, as shown in FIG. 1, a feeding mechanism 2 for moving the optical disk 1 in the radial direction, that is, the direction of arrow A using a tracking error signal detected from the optical disk 1, and an optical disk. 1
An optical pickup unit 3 for recording an information signal by using the light irradiated on the optical disc, and for reproducing the information signal recorded by the light irradiated on the optical disc 1, and an optical pickup unit for driving the optical pickup unit 3. Drive circuit 4
And a biaxial actuator drive unit 5 that drives a biaxial actuator in the optical pickup unit 3 according to the movement of the optical pickup unit 3, and a control that controls the operations of the optical pickup unit drive circuit 4 and the biaxial actuator drive unit 5. It has a microcomputer 6 as means, a counter 7 for counting the number of tracks as the movement amount of the optical pickup unit drive circuit 4, and a low pass filter 8.

The feed mechanism 2 for feeding the optical pickup unit 3 in the direction of arrow A in FIG. 1 outputs a driving force for coarsely moving in response to a drive signal from the optical pickup unit drive circuit 4, and a coarse movement drive unit 2a. It is composed of, for example, a gear transmission mechanism that transmits the driving force from the coarse movement driving unit 2a. In general, for example, a shaft 2b penetrates the optical pickup unit 3 to move the optical pickup unit 3 along the radial direction of the optical disc 1. A coarse movement drive unit 2a, for example, is arranged on the tip side of the shaft 2b.

As a more specific example of this feeding mechanism, a sled motor is used for the coarse movement driving section 2a. It may be configured with, for example, a rack gear that meshes with the rotation shaft of the thread motor having a pinion gear that transmits the rotational driving force of the thread motor. When this configuration is used, the optical pickup unit 3 is arranged on the back side where the gear of the rack gear is not formed.

The optical pickup unit 3 includes a housing 3A of the optical pickup unit 3, a biaxial actuator 3c for performing focus control and tracking control of the optical system 3a and the objective lens 3b, and an optical system 3a and a biaxial actuator 3c. And elastic members 3d and 3d that connect the objective lens 3b with each other.

The biaxial actuator driving section 5 is an amplifier 5 for amplifying a tracking error signal from, for example, a two-divided detector 3e arranged in the optical pickup section 3.
a, a servo circuit 5b for outputting a control signal according to the supplied tracking error signal, and a servo circuit 5b.
Drive circuit 5c for outputting a drive signal according to the control signal from
Composed of and.

The drive circuit 5c outputs a drive signal in response to a control signal from the microcomputer 6 as a control means. The circuit configuration of the drive circuit 5c is, for example, as shown in FIG. 2, a constant current source 501, 5 that outputs a constant current.
02, output switches from the constant current sources 501 and 502, output signals from the servo circuit 5b, and switch switches 504 and 505 that switch and supply the output from the constant current sources 501 and 502 to one end side of the gain amplifier 503 in response to a switch control signal from the microcomputer 6. Is switched to the other end of the gain amplifier 503 via the resistor R1 in response to a switching control signal from the microcomputer 6, and the switching switch 506 and the switching switch 50 are provided.
4 to 506, and an amplifier 507 that amplifies the input signal supplied. Here, the constant current sources 501, 5
The voltages output from 02 have opposite polarities.

The drive circuit 5c outputs a drive signal for moving the entire objective lens 3b to the drive coil 10. The drive coil 10 moves in accordance with this drive signal, and controls the movement of the objective lens 3b in the direction of arrow A in FIG. 1 so that it is always located at the midpoint in the radial direction inside the housing 3A.

Next, the operation of the optical disk device having the above-mentioned structure will be described with reference to FIGS. In the optical disk device, a track jump command signal shown in FIG. 3A, for example, is input to the microcomputer 6 that controls the operation of each unit via the input terminal 11. This command signal is a signal of a large track jump for moving a distance of several millimeters on the optical disk at high speed in the direction of arrow A in FIG. At this time, the microcomputer 6 receiving this command signal switches to the terminal b side of the changeover switch 9 shown in FIG. 1 according to the changeover control signal from the microcomputer 6. By this switching operation, for example, a command signal from the microcomputer 6 is supplied to the optical pickup unit drive circuit 4. The optical pickup section drive circuit 4 outputs a drive signal corresponding to the command signal to the coarse movement drive section 2a.

The coarse drive unit 2a rotates according to the drive signal supplied. The driving force of the coarse motion drive unit 2a is transmitted to the shaft 2b via a transmission mechanism. By the driving force thus supplied, the optical pickup section 3 which is integrally arranged with the shaft 2b is moved in the direction of arrow A in FIG. This rough movement continues until the target track position is jumped from the track position where the optical pickup unit 3 is currently arranged. The period from the track position to the target track position corresponds to the level "H" period in FIG. During this period, the optical pickup unit 3 is moving at a constant speed.

The microcomputer 6 calculates and obtains how many tracks this level "H" is. Further, the optical disk device supplies a tracking error signal detected by, for example, a two-divided detector, to a counter 7 that measures a movement amount via an amplifier 5a of the biaxial actuator driving section 5. The counter 7 counts the number of tracks traversed by the light beam spot based on the mirror signal in the supplied tracking error signal, and outputs it to the microcomputer 6. The microcomputer 6 switches to the terminal b side of the changeover switch 9 until the number of tracks calculated and the count value supplied from the counter 7 match. In this way, the coarse movement drive unit 2a sends the optical pickup unit 3 to the target track position.

Since the coarse movement of the optical pickup unit 3 by the feeding mechanism 2 is performed at a high speed by a uniform velocity motion as shown in FIG. 3A, the objective lens 3b connected by the elastic members 3d and 3d is inertial. Therefore, it may be left behind and cannot follow the movement of the optical pickup unit 3. For this reason, the objective lens 3 b is used as the housing 3 of the optical pickup unit 3.
It may collide with the inner wall of A and the focus control in the ON state may not be performed. In order to solve this problem, the objective lens 3b is moved in the same direction as the moving direction of the optical pickup unit 3.

The objective lens 3b is usually controlled so as to be arranged at the midpoint position of the objective lens 3b in the optical pickup section. In order to recover the delay of the objective lens 3b when the optical pickup unit 3 accesses the optical disc 1 at a high speed, the optical pickup unit 3 has to be accelerated for _a certain period T _a shown in FIG. 3B. In order to perform this acceleration, at the same time when the command signal is input to the microcomputer 6, the microcomputer 6 turns on the changeover switches 504 and 506 shown in FIG. 2 by the output changeover control signal. By this switching process of the changeover switch 504,
A positive control pulse, for example, is applied as a pulse for acceleration shown in FIG. 3B to one end of the gain amplifier 503. The control pulse is controlled by the microcomputer 6 so as to supply it for _a predetermined period T _a as shown in FIG. By this control, the objective lens 3b
Can be operated by following the coarse movement direction of the optical pickup unit 3. Further, by adjusting the period of the control pulse and the like, the objective lens 3b can be always located at the midpoint in the radial direction in the housing 3A, for example. The position can be controlled.

The period during which this command signal is supplied is a so-called track jump period. The optical disc device has tracking control turned off and focus control turned on. The objective lens 3b can be moved following the optical system 3a in the optical pickup unit 3 and the biaxial actuator 3c. Therefore, the focus control can be accurately performed even during this jump.

Next, when the microcomputer 6 determines that the movement from the counter value of the counter 7 to the instructed target track is completed by the command signal, the microcomputer 6 receives the changeover control signal and supplies the changeover switch. Switch to the terminal a side of 9. By this switching operation, the optical pickup section drive circuit 4 stops the supply of the drive signal that has been supplied to the coarse movement drive section 2a. By stopping the supply of the drive signal, the coarse movement of the optical pickup unit 3 is completed.

However, the objective lens 3b in the optical pickup section 3 has an inertia acting to continue the constant velocity motion. Therefore, the sudden stop of the coarse movement of the optical pickup unit 3 may cause the objective lens 3b to collide with the inner wall in the coarse movement direction. In order to avoid this collision, the microcomputer 6 uses the objective lens 3b.
Must reduce the speed that he has. For this reason,
At the same time when the command signal changes from the level "H" to the level "L", the microcomputer 6 switches
Turn on 506. By performing the switching operation in this manner, the control pulse is supplied for a certain period T _b as shown in FIG. 3B, for example. This deceleration pulse is a negative pulse.

[0031] By the deceleration pulse is a fixed period T _b is applied, the driving coil 10 generates the restraint force in the direction opposite to the direction of the constant velocity movement of the objective lens 3b. With the supplied restraining force, it is possible to prevent the target track from being overtraveled and to shorten the time required for settling after the optical pickup unit 3 is accessed at high speed.

Here, the periods T _a and T _b to which the acceleration pulse and the deceleration pulse are applied are adjusted and set in advance so as to prevent collision of the objective lens in consideration of the amount of current. .

For coarse movement of the optical pickup section 3 during a normal track jump operation, the microcomputer 6 switches to the terminal a side of the changeover switch 9 and the LPF 8 is switched.
The signal through the optical pickup unit is supplied to the optical pickup unit drive circuit 4. The optical pickup unit drive circuit 4 supplies a drive signal to the sled motor 2a to roughly move the optical pickup unit 3.

With the above-mentioned structure, when the target track is accessed at high speed, the objective lens of the biaxial actuator which is connected to the optical system in the optical pickup section by the elastic member is left unremoved or the objective lens is left. It is possible to prevent an offset of the so-called objective lens caused by the excessive movement of As a result, the pull-in time until the swing of the objective lens is settled after reaching the target track can be significantly shortened as compared with the conventional required time. This reduction in processing time after high-speed access is very significant for a large-capacity optical disc.

Further, according to the structure of this embodiment, the optical pickup unit can be accessed at a high speed with a simple structure without providing a position sensor unit as a position detecting means which is conventionally provided. Thereby, the cost at the time of manufacturing can be reduced.

The present invention is not limited to the method of measuring the number of track-cut mirror signals in the above-mentioned embodiment, but the number of tracks is measured by using the encoder attached to the feeding mechanism 2. You may.

[0037]

In the optical disk device according to the present invention, the optical pickup unit is driven in the moving direction by the driving means at the same time when the movement of the optical pickup unit is started by the feeding mechanism, so that the objective lens is not left behind due to inertia. By moving the objective lens in the opposite direction to the moving direction by the driving means at the same time as the movement is completed, the optical pickup unit is prevented from overshooting the target track. The movement speed of the objective lens is reduced for a certain period of time to avoid collision of the objective lens inside the housing of the optical pickup unit, so-called objective lens offset is prevented, and the swinging of the objective lens after reaching the target track is settled. It is possible to greatly shorten the pull-in time until it is carried out as compared with the conventional required time.

Further, according to the present invention, it is possible to perform high-speed access to the optical pickup section with a simple structure without providing a position sensor section as a position detecting means, which is conventionally provided. Thereby, the cost at the time of manufacturing can be reduced.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic block configuration of an optical disc device according to the present invention.

FIG. 2 is a circuit diagram showing a specific circuit configuration of a drive circuit of the optical disc device.

FIG. 3 is a timing chart for explaining a timing relationship of jump control in the optical disc device.

FIG. 4 is a schematic diagram for explaining the operation of the conventional objective lens during movement.

FIG. 5 is a diagram schematically showing a configuration for detecting the position of a conventional objective lens.

[Explanation of symbols]

1 --- Optical disk 2 --- Feeding mechanism during coarse movement of optical pickup section 3 --- Optical pickup section 4 ...・ ・ ・ ・ ・ ・ ・ ・ Optical pickup drive circuit 5 ・ ・ ・ ・ ・ Biaxial actuator drive 6 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Microcomputer 7 ・ ・ ・・ ・ ・ Counter 8 ・ ・ ・ ・ ・ LPF 9, 504, 505, 506 ・ ・ ・ Changeover switch 10 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Actuator 5a ・ ・ ・ ・ ・ ・ ・ ・Amplifier 5b ・ ・ ・ ・ ・ ・ Servo circuit 5c ・ ・ ・ ・ ・ ・ ・ Drive circuit 501, 502 ・ ・ Constant current source

Claims (1)

[Claims] 1. An optical pickup unit comprising an actuator for controlling an objective lens in an optical axis direction and a track direction, and an optical unit for detecting information of a disc-shaped recording medium and a servo error signal, and a disc having the optical pickup unit. Feeding mechanism for moving the recording medium in the radial direction, driving means for driving an objective lens disposed in the optical pickup section via an elastic member, tracking control turned off and the optical pickup section for feeding When the mechanism jumps and moves to the target track, the objective lens is driven in the moving direction by the driving means at the same time when the movement starts, and the objective lens moves in the opposite direction to the moving direction at the same time when the movement ends. An optical disk device comprising: a control unit that is driven by a drive unit.