JP2002358664A - Optical pickup moving device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical pickup moving device provided with a control mechanism capable of precisely controlling the movement of an optical pickup. SOLUTION: In the optical pickup moving device provided with a motor 1 and transmission mechanisms 13, 12 and 16 for transmitting the driving force of the motor 1 to an optical pickup, a detecting plate 15 rotated similarly to the motor 1, a detector 6 for detecting the rotation of the detecting plate 15, and a driving control means 7 for controlling the rotation of the motor 1 by a rotational angle signal generated by the detector 6 are disposed. Since the moving amount of the optical pickup can be finely controlled by the minimum resolution (half in the case of 2 phases) of the detector 6, the optical pickup moving amount per motor rotation can be set large. Thus, the stable optical axis correction feeing and the low-rotation and fast long-distance movement of the optical pickup can be carried out.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical pickup moving load for moving an optical pickup from the inner circumference to the outer circumference of a disk in order to read information recorded on the disk, and more particularly to an improvement in a control system. is there.

[0002]

2. Description of the Related Art An optical disk apparatus moves an optical pickup at high speed in a radial direction of an optical disk in order to access a track at a desired position where information on the optical disk is recorded.
Also, to track the playback position of the track during playback,
An optical pickup moving device for minutely moving the optical pickup (optical axis correction feed) is provided.

[0003] This moving device is generally configured to transmit the rotation of a motor as a drive source to a drive shaft, and to transmit the rotation of the drive shaft to an optical pickup by meshing gears or the like.
In order for the optical pickup to be able to access the target position accurately, it is necessary to properly control the feed mechanism and a mechanical structure such as a drive shaft and gears that accurately transmit the driving force according to the control. From such a viewpoint, various improvements have been made to the optical pickup moving device.

Japanese Utility Model Publication No. Hei 6-2071 discloses a driving force transmission device in which the relationship between a rack fixed to the optical pickup side and a gear for transmitting driving force is improved. As shown in FIG. 7, this apparatus includes a fixed rack 3 for fixing a rack moving together with the optical pickup to the optical pickup, and a slide rack 9 for sliding on the fixed rack 3.
And a double rack. The fixed rack 3 and the slide rack 9 are urged in opposite directions by a spring. A driving force is transmitted from a drive shaft to the gear 12 that meshes with the double rack, and the double rack and the optical pickup move to the left and right on the paper according to the rotation of the gear 12. When the double rack and the optical pickup move to the left and reach the end, the stopper 10 collides with the fixed rack 3,
Movement stops.

[0005] The height of the teeth 3a at the final end of the fixed rack 3 is formed lower than the heights of the other teeth. Therefore, when the fixed rack 3 moves to the end and hits the stopper 10, it stops. Then, the gear 3 is disengaged from the gear 3a at the last end, and the rotational force of the gear 12 does not act on the fixed rack 3. Therefore, damage to the teeth of the fixed rack 3 and the gear 12 can be prevented.

In this state, since the slide rack 9 and the gear 12 are engaged with each other by one tooth, the slide rack 9
, The slide rack 9 is pushed leftward by one tooth, but is returned by the urging force of the spring between the fixed rack 3 and the slide rack 9, and meshes with the gear 12 again. This operation is repeated until stops. Next, when the gear 12 rotates reversely, first, the slide rack 9
12 and then the fixed rack 3 is
With the movement of the gear, it moves rightward and meshes with the gear 12, and the double rack and the optical pickup can move in the opposite direction (rightward on the paper).

Japanese Utility Model Laid-Open Publication No. 1-107063 discloses a moving device having a mechanism for accurately controlling the feed of an optical pickup. This device is shown in FIG.
As shown in FIG. 1, a motor 1 as a drive source for moving the optical pickup 2, a transmission mechanism 13 for transmitting the driving force of the drive source, and a feed screw for directly moving the optical pickup 2
14, a detection plate 15 attached to the tip of the feed screw 14, a rotary encoder 6 for detecting the rotation of the detection plate 15, and a movement amount of the optical pickup 2 from the lead-in position based on the output of the rotary encoder 6. Operation means 8 for performing the operation. Reference numeral 4 denotes a guide shaft inserted through a hole of the optical pickup 2, and the optical pickup 2 moves along the guide shaft 4.

In this apparatus, the rotation of the feed screw 14 is detected by the detection plate 15 attached to the tip of the feed screw 14 and the rotary encoder 6 having the light detection element.
Outputs a pulse signal corresponding to the rotation speed. The amount of movement of the optical pickup 2 per pulse is known from the reduction ratio of the driving force transmission mechanism 13, the lead pitch of the feed screw 14, and the number of divided encoders.
The amount of movement of the optical pickup 2 is obtained by counting the number of pulses output from the optical pickup 2 by the calculating means 8. Therefore, the optical pickup 2 can be moved while counting the pulse signals for the distance to the target position, so that the target position can be accessed accurately.

[0009]

However, the conventional optical pickup moving device has the following problems. With regard to the mechanical structure of the drive mechanism, when the fixed rack reaches the end, when the operation proceeds in the opposite direction, the fixed rack and the gear mesh again, but at this time, the teeth of the fixed rack and the slide rack are engaged. If there is backlash between the gears and they are out of synchronization, smooth meshing is not possible, and the gear and the fixed rack are brought into contact with each other to damage the teeth.

The double rack has two racks and one spring.
Since the number of components is one, the number of parts increases. Further, when the rack is attached to and fixed to the optical pickup, fine adjustment is required so that the pitch distance between the rack and the gear becomes uniform within the moving range of the optical pickup.

As for the control mechanism, when the access operation of the optical pickup is controlled by counting the number of rotations of the feed shaft, an inertial force acts if the brake is applied immediately before the target position. Overruns the target position. Therefore, the brake is applied a certain distance before the target position. Is related to this moving speed, so even if the brake is applied a fixed distance before the target position, the remaining distance from the stop position to the target position is not uniform. Therefore, it is difficult to access the target position once, and in the worst case, the access operation must be repeated several times.

The present invention solves the problem of the control mechanism among the conventional problems, and provides an optical pickup moving device having a control mechanism capable of precisely controlling the movement of the optical pickup. It is intended to provide.

[0013]

Therefore, in the optical pickup moving device of the present invention, the rotation of the detecting plate which rotates in the same direction as the motor is detected, and the rotation of the motor is controlled. Therefore, the rotation of the motor can be controlled up to the minimum rotation angle corresponding to the resolution of the detection plate.

The speed of the optical pickup is controlled in accordance with a predetermined profile such as acceleration, constant speed, and deceleration. Therefore, variation in the stop position of the optical pickup can be reduced.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention according to claim 1 of the present invention provides an optical pickup moving device having a motor and a transmission mechanism for transmitting a driving force of the motor to the optical pickup, in which the same rotation as the motor is performed. A detection plate, a detector for detecting the rotation of the detection plate, and drive control means for controlling the rotation of the motor based on a rotation angle signal generated by the detector. Since the drive can be minutely controlled with the minimum resolution (half in the case of two phases), it is possible to set a large amount of movement of the optical pickup per rotation of the motor, and to achieve stable optical axis correction feed of the optical pickup. And high-speed movement of the optical pickup at a low rotation over a long distance.

According to a second aspect of the present invention, there is provided a calculating means for calculating the moving speed of the optical pickup based on the rotation angle signal generated by the detector, and the drive control means refers to the calculation result of the calculating means. The moving speed of the optical pickup is controlled according to a predetermined speed profile. By controlling the moving speed of the optical pickup, the variation in the stop position of the optical pickup due to the moving distance can be reduced, and the target position can be controlled. Can be accurately moved.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. First, the overall structure of the optical pickup moving device according to the embodiment will be described. This device is
As shown in FIG. 6, an optical pickup 2 that moves along a guide shaft 4, a rack 3 that is fixed to the optical pickup 2 and integrally includes a guide portion 5 for positioning at the time of fixing, and a motor , A transmission mechanism 13 for transmitting the driving force of the driving source 1 to the rack 3, and a spur gear
12, a detection plate 15 attached to the tip of the motor rotation shaft, a detector 6 for detecting the rotation of the detection plate 15, and a calculation device 8 for calculating the moving speed of the optical pickup 2 based on the detection result of the detector 6. And a drive control device 7 for controlling the rotation of the motor.

An embodiment in which each part of the apparatus is improved will be described with reference to drawings in which related parts are extracted.
I will explain separately.

(First Embodiment) A first embodiment is described as follows.
When moving the optical pickup that has reached the end in the opposite direction,
This is a configuration for preventing gears and racks from being inappropriately meshed with each other to damage the teeth. This device is shown in FIG.
As shown in the figure, a fixed rack 3 attached to and fixed to the optical pickup 2, a slide rack 9 that slides on the fixed rack 3, and a preload that is mounted between the fixed rack 3 and the slide rack 9 and urges them in opposite directions. A rack spring 11 to be provided, a gear (pinion) 12 meshing with the fixed rack 3 and the slide rack 9, and the motor 1 as a drive source.
A transmission mechanism 13 for transmitting the driving force of the motor 1 to the fixed rack 3 and the slide rack 9 via the gear 12 and a stopper 10 for stopping the fixed rack 3 when the optical pickup 2 reaches the end. The stopper 10 is arranged before and after in the traveling direction of the optical pickup 2.

The fixed rack 3 and the slide rack 9 are mounted so as to be shifted by one tooth, and the tip of the last tooth of the fixed rack 3 and the frontmost tooth of the slide rack 9 are:
It is formed in a tapered shape so as to be cut obliquely to the side of an adjacent tooth (FIG. 1 (C)).

In this apparatus, in order to move the optical pickup 2, the motor 1 is driven, and the transmission mechanism 13 and the gear 12 are driven.
, The driving force is transmitted to a double rack including the fixed rack 3 and the slide rack 9. When the optical pickup 2 moves to the outer peripheral position (end) in the disk radial direction, the fixed rack 3 collides with the stopper 10 and stops (FIG. 1B). However, if the motor 1 does not stop instantaneously due to the inertial force or does not stop due to an abnormality or the like, the slide rack 9 that has not collided with the stopper 10 continues to be pushed by the rotational force of the gear 12. When the optical pickup 2 moves to the end position of the inner circumference in the disk radial direction, the relationship is reversed, and the slide rack 9 collides with the stopper 10 and the fixed rack 3 which does not collide with the stopper 10 is moved. The gear 12 keeps being pressed by the rotational force.

At this time, the rack stopped by the stopper 10 is disengaged from the gear 12 and does not damage the teeth. On the other hand, the rack which is not stopped by the stopper 10 is meshed with the gear 12 by one tooth. The operation is repeated until the motor 1 stops. As a result, the teeth do not bite between the gear and the rack, and the teeth are not damaged.

Next, when the motor 1 is rotated in the reverse direction to move the optical pickup 2 in the opposite direction, the rack which has already meshed is pushed by the gear 12, and then the tapered tooth profile of the other rack and the gear 12 are connected. Begins to mesh. At this time, since the tapered tooth profile has an inclined tip, the gear 12
The optical pickup 2 can be moved without interfering with the tooth tip of the optical pickup 2 and smoothly pressed and meshed. Thus, by adopting this embodiment, it is possible to prevent the teeth from being damaged due to the contact between the rack and the gear tip, and it is possible to smoothly engage the rack and the gear. Also, backlash between the rack and the gear can be eliminated.

(Second Embodiment) In a second embodiment,
This is a configuration for reducing the number of parts of the rack. In this apparatus, as shown in FIG.
The rack 3 fixed to the optical pickup 2 is provided with cutouts 3 b, 3
It is composed of one resin plate provided with c. The notches 3b and 3c are provided at the front and rear portions of the rack 3, so that the width of the front and rear tooth row portions is reduced.

In this apparatus, even if the gear 12 rotates after the rack 3 reaches the end, as shown in FIG. 2B, the rack 3 is bent in a direction in which the gear 3 is disengaged from the gear 12 and escapes. Due to the rotational force of the gear 12, no extra force is applied to the teeth, and damage to the teeth is prevented.

In this apparatus, when the spur gear 12 is rotated by the driving of the motor and the rack 3 moves to reach the end of the inner or outer periphery of the optical pickup 2, the rack 3 is moved to the stopper.
At 10 the optical pickup 2 stops. At this time, if the motor continues to rotate due to the inertia force of the motor, the abnormality of the motor, or the like, the spur gear 12 continues to push the rack 3. It escapes by bending in the direction in which the engagement is released. Therefore, even if the spur gear 12 rotates, no extra force is applied to the spur gear 12 and the teeth of the rack 3. And, by repeating this operation until the motor stops, no biting of the gear occurs,
Damage to teeth can be prevented. When the reverse rotation operation is started, the rack 3 returns to the initial state position, meshes with the spur gear 12, and can move the optical pickup 2 in the reverse direction.

(Third Embodiment) A third embodiment is directed to
This is a configuration that simplifies positioning when the rack is fixed to the optical pickup. In this device, as shown in FIG. 3, an optical pickup 2 sliding on a guide shaft 4 is used.
And a rack 3 having guide portions 5 at the front and rear. The guide portion 5 has a positioning function, and when the rack 3 is fixed to the optical pickup 2, the position of the rack 3 is determined by positioning the guide shaft 4 between the forks of the guide portion 5.

The rack 3 is mounted on the reference surface (2a) of the optical pickup 2. At this time, the pitch listening distance between the rack 3 and the spur gear 12 is kept constant regardless of the position of the optical pickup 2 that moves while being guided by the guide shaft 4 from the inner circumference to the outer circumference of the disk. The rack 3 must be fixed to the optical pickup 2. If the distance between the pitches varies depending on the position of the optical pickup 2, the meshing load between the rack 3 and the spur gear 12 changes depending on the position of the optical pickup 2.

When the guide 5 is not provided, the rack 3 is fixed to the reference surface (2a) of the optical pickup 2 while adjusting it. And the pitch between the guide hole of the optical pickup 2 for receiving the guide shaft 4 and the reference surface 2a, the parallelism between the mounting reference surface of the rack 3 and the pitch line of the tooth row, and the like. Therefore, adjustment is difficult.

However, as in this embodiment, the rack 3
In the case where the guide portion 5 is provided, the rack 3 can be attached to the optical pickup 2 with reference to the guide shaft 4 so that the guide portion 5 is in contact with the guide shaft 4. In this case, only the parallelism between the guide portion 5 and the pitch line of the tooth row in the rack 3 becomes an error factor. Therefore, if the rack 3 is precisely processed, the parallelism can be adjusted when the rack 3 is mounted. Is performed, the parallelism error between the rack 3 and the spur gear 12 can be reduced to almost zero.

Therefore, no matter where the optical pickup 2 moves from the inner circumference to the outer circumference, the distance between the pitches of the spur gear 12 and the rack 3 does not fluctuate. , Disengagement and the like are eliminated. for that reason,
Rotational load fluctuation is reduced, and stable movement of the optical pickup 2 can be realized. In addition, it is possible to eliminate variations in the mounting position of the rack 3.

(Fourth Embodiment) In a fourth embodiment,
This is a configuration of a control system that enables stable micro movement of the optical pickup and long-distance movement of the optical pickup at high speed. As shown in FIG. 4 (a), this device includes a motor 1 which is a driving source for moving the optical pickup, a transmission means 13 fixed to a motor shaft for transmitting the driving force of the motor, A fixed detection plate 15 for detecting the rotation angle of the motor shaft, a gear 12 to which the driving force of the motor 1 is transmitted through the transmission means 13, and the optical pickup is moved by the driving force transmitted from the gear 12. A direct drive force transmitting means 16 comprising a rack or a feed screw, a detector 6 for detecting the rotation of the detection plate 15 rotating in the same direction as the motor 1 and outputting a rotation angle signal, and a rotation angle generated by the detector 6 And a drive control device 7 for controlling the motor 1 to rotate by the target rotation angle using the signal.

In this device, the detection plate 15 rotates by the same angle as the rotation angle of the motor 1, the detector 6 which detects the rotation angle of the detection plate 15 outputs a rotation angle signal, and the drive control device 7 The rotation angle signal is fetched, and the drive control of the motor 1 is performed so that the optical pickup rotates by a target rotation angle that causes the optical pickup to move a predetermined distance. FIG. 2B shows the relationship between the motor rotation angle signal output from the detector 6 and the motor drive signal output from the drive control device 7 to the motor, and corresponds to two pulses of the rotation angle signal. The case where the motor is driven only for the time is shown.

In this closed loop control, the rotation of the motor 1 is directly detected by a detecting means including the detecting plate 15 and the detector 6, and
Control, the motor 1 rotates at the minimum rotation angle corresponding to the minimum resolution of this detection means (half for two-phase).
Can be precisely controlled for rotation. The stable stop angle inherent to the motor 1 is determined by the number of phases of the motor coil and the magnet, and the minimum rotation angle is 1/6 rotation (60 °).
In this closed loop, drive control at 1/6 rotation or less can be performed by setting the resolution of the detection means to 60 ° or less. As the resolution of the detection means is smaller, drive control at a smaller angle becomes possible.

Therefore, this closed loop control enables stable optical axis correction feed (small movement) of the optical pickup. In this case, even if the amount of movement of the optical pickup per rotation of the motor is increased, the rotation angle of the motor can be minutely controlled, so that a stable minute movement of the optical pickup can be realized. In addition, by increasing the amount of movement of the optical pickup per rotation of the motor in this way, it becomes possible to move the optical pickup at a high speed over a long distance (high-speed access) with a small rotation speed of the motor.

(Fifth Embodiment) In the fifth embodiment,
This is a configuration of a control system that controls the moving speed of the optical pickup to reduce variation in stop positions. This device is shown in FIG.
As shown in (a), an arithmetic unit 8 that calculates the moving speed of the optical pickup 2 based on the rotation angle signal output from the detector 6, and the moving speed of the optical pickup 2 is a target speed profile (acceleration, constant speed, And a drive control device 7 for controlling the rotation of the motor 1 so as to coincide with the deceleration.
Other configurations are the same as those of the fourth embodiment (FIG. 4A).

In this apparatus, the arithmetic unit 8 calculates the rotation speed of the motor 1 based on the rotation angle signal generated by the detector 6, and converts it into the actual moving speed of the optical pickup. When the target position is input, the drive control device 7
While comparing the actual moving speed obtained by the arithmetic unit 8, the moving speed of the optical pickup changes along time with the order of acceleration, constant speed, and deceleration. Control the speed. At this time, the drive control device 7 calculates the moving distance of the optical pickup from the moving time and the moving speed, determines the time required to reach the target position, determines the deceleration start timing, and determines whether the moving distance reaches the target position. When the distance is reached, the rotation of the motor 1 is stopped.
By doing so, it is possible to improve the accuracy with which the optical pickup reaches the target position, and to reduce the variation in the stop position due to the moving distance. As a result, the number of re-access operations is reduced, and a high-speed access operation is enabled.

[0038]

As is apparent from the above description, the optical pickup moving device of the present invention directly detects the rotation angle of the motor and uses the detection result to control the rotation of the motor. It can be controlled, and enables stable optical axis correction feed and high-speed access operation.

In the apparatus for controlling the speed of the optical pickup during the access operation, the variation in the stop position of the optical pickup can be reduced and the optical pickup can be moved to the target position with high accuracy.

[Brief description of the drawings]

FIG. 1 is a schematic view of an optical pickup moving device according to a first embodiment of the present invention;

FIG. 2 is a schematic view of an optical pickup moving device according to a second embodiment of the present invention;

FIG. 3 is a schematic diagram of an optical pickup moving device according to a third embodiment of the present invention;

FIG. 4 is a schematic view of an optical pickup moving device according to a fourth embodiment of the present invention;

FIG. 5 is a schematic view of an optical pickup moving device according to a fifth embodiment of the present invention;

FIG. 6 is a diagram showing an entire configuration of an optical pickup moving device according to the embodiment of the present invention;

FIG. 7 is a diagram showing a configuration of a rack and gears of a conventional optical pickup moving device.

FIG. 8 is a schematic view of a conventional optical pickup moving device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Drive source (motor) 2 Optical pick-up 3 Fixed rack 4 Guide shaft 5 Guide part 6 Detecting means (detector) 7 Drive control device 8 Computing means (Computing device) 9 Slide rack 10 Stopper 11 Elastic means (spring) 12 Gear ( Pinion) 13 Driving force transmission mechanism 14 Feed screw 15 Detection plate 16 Direct driving force transmission means (rack or feed screw)

Claims (2)

[Claims] 1. An optical pickup moving device comprising: a motor; and a transmission mechanism for transmitting a driving force of the motor to the optical pickup. And a drive control means for controlling the rotation of the motor based on a rotation angle signal generated by the detector. 2. The optical pickup according to claim 1, further comprising a calculating unit that calculates a moving speed of the optical pickup based on a rotation angle signal generated by the detector, wherein the drive control unit refers to a calculation result of the calculating unit, and The optical pickup moving device according to claim 1, wherein the moving speed of the optical pickup is controlled according to a predetermined speed profile.