JP2004273062A - Optical pickup feed mechanism - Google Patents

Abstract

Provided is an inexpensive optical pickup feed mechanism that can stop an optical pickup at an initial position with high accuracy and has a simple structure.
An optical pickup for reading information from a disk, a guide shaft fixed to a base such that an axis direction is in a radial direction of the disk, and a drive mechanism for moving the optical pickup along the guide shaft. When the optical pickup 1 is moved to the inner peripheral side of the disk by this drive mechanism, the optical pickup 1 stops by abutting on the protrusion 10b of the base 10 and at the stopped position. Is configured to face a reading start position provided on the inner peripheral side of the.
[Selection diagram] Fig. 1

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an optical pickup feeding mechanism for moving an optical pickup.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, there is known a disk drive device that reads and reproduces information recorded on an optical disk (hereinafter, simply referred to as a “disk”) such as a CD (Compact Disc) and a DVD (Digital Versatile Disc). In this disk drive device, an optical pickup is used to read information recorded on a disk.
[0003]
Generally, a TOC (Table Of Contents) area is formed on the innermost side of the disc, and information to be reproduced is recorded on the outer side of the TOC area. In the TOC area, the number, type, track position, size, and the like of information recorded on the disc are recorded. Therefore, when reproducing the information recorded on the disc, first, the optical pickup is moved to the innermost peripheral side of the disc, and the optical pickup (strictly, the objective lens mounted on the optical pickup) is moved to a position in the TOC area. It is necessary to stop at a position facing a specific position. Hereinafter, this position is referred to as an “initial position” in this specification.
[0004]
The movement and stop of the optical pickup are performed by an optical pickup feed mechanism. The optical pickup feed mechanism has a guide shaft arranged in the radial direction of the disk, and the optical pickup is mounted movably in the radial direction of the disk along the guide shaft. For example, a microswitch for detecting the innermost position is provided at the inner moving end of the optical pickup. When the optical pickup moves to the initial position, the microswitch is pressed by the optical pickup and turned on. When the microswitch is turned on, the movement of the optical pickup is stopped, and reading of information recorded in the TOC area is started.
[0005]
As a technique for controlling the feed of the pickup, Patent Document 1 detects the load of the pickup feed mechanism by measuring the value of the drive current of the pickup feed motor while moving the pickup from the inner side to the outer side. In addition, a method is disclosed in which the driving voltage of the pickup feed motor is corrected and changed according to the load, thereby controlling the feed operation of the pickup for reading the signal recorded on the disk.
[0006]
[Patent Document 1]
JP-A-8-87843
[Problems to be solved by the invention]
However, the above-described conventional optical pickup feeding mechanism has the following problem. In other words, the microswitch for detecting the innermost peripheral position is required to stop the optical pickup at the initial position with an accuracy equal to or more than an error due to the variation because the time at which the microswitch is turned on (for example, the depth of the stroke) varies among individuals. Is difficult. In addition, since a component called a switch is used to determine whether the optical pickup has stopped at the initial position, the structure of the optical pickup feed mechanism is complicated, and the cost is increased.
[0008]
SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem, and an object of the present invention is to provide an inexpensive optical pickup feed mechanism that can stop an optical pickup at an initial position with high accuracy and has a simple structure. Aim.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, an optical pickup feed mechanism according to the present invention includes: an optical pickup that reads information from a disk; a guide shaft fixed to a base such that an axis direction is a radial direction of the disk; A drive mechanism for moving the optical pickup along the guide shaft, wherein the optical pickup comes into contact with a part of the base when the drive mechanism is moved to the inner peripheral side of the disk, and stops. The stop position opposes a reading start position provided on the inner peripheral side of the disk.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
Embodiment 1 FIG.
FIG. 1 is a plan view schematically showing a configuration of an optical pickup feed mechanism according to Embodiment 1 of the present invention. The optical pickup feed mechanism includes an optical pickup 1, a drive shaft 2, a guide shaft 3, a motor 4, a first gear 5, a second gear 6, a third gear 7, a bearing 8, a bearing 9, a base 10, a control device 11, It comprises a drive circuit 12 and a current detector 13. The drive mechanism of the present invention includes a drive shaft 2, a motor 4, a first gear 5, a second gear 6, a third gear 7, a bearing 8, and a bearing 9. Note that a drive mechanism is attached to the base 10.
[0011]
The optical pickup 1 includes an objective lens 1a for irradiating a disk (not shown) with light and taking in reflected light from the disk. The optical pickup 1 reads information from a disk via the objective lens 1a and writes information on the disk. The disc is set so that its information recording surface faces the objective lens 1a of the optical pickup 1 (so as to be parallel to the paper surface of FIG. 1). At one corner of the optical pickup 1, a projection 1b functioning as a stopper is provided.
[0012]
The drive shaft 2 is rotatably supported by bearings 8 and 9 fixed to a base 10. The drive shaft 2 is formed of a male screw, and is screwed to a female screw (not shown) formed at one end of the optical pickup 1. The optical pickup 1 moves in the radial direction of the disk (the direction of arrow AB in the drawing) as the drive shaft 2 rotates.
[0013]
Both ends of the guide shaft 3 are fixed to the base 10. The guide shaft 3 slidably supports the other end of the optical pickup 1 (the end facing the one end), and functions as a guide when the optical pickup 1 moves. The movement of the optical pickup 1 toward the inner circumference side (the arrow A side) of the disk is restricted by the protrusion 1b of the optical pickup 1 coming into contact with the protrusion 10b of the opening 10a formed in the base 10. The optical pickup 1 accurately opposes a specific position in the TOC area provided on the inner peripheral side of the disc, that is, a reading start position, at the initial position stopped by the regulation. The adjustment of the initial position is performed by adjusting the position where the protrusion 1b and the protrusion 10b are formed.
[0014]
The motor 4 generates a driving force for moving the optical pickup 1. A first gear 5 is fixed to a rotating shaft of the motor 4. The first gear 5 meshes with a second gear 6 rotatably supported by a bearing 8. The second gear 6 meshes with a third gear 7 fixed to the drive shaft 2. The driving force of the motor 4 is transmitted to the drive shaft 2 by the first gear 5, the second gear 6, and the third gear 7 to rotate the drive shaft 2.
[0015]
The control device 11 controls the start and stop of the rotation of the motor 4 by sending a start signal and a stop signal to the drive circuit 12. Hereinafter, rotation of the motor 4 that moves the optical pickup 1 toward the inner periphery of the disk is referred to as forward rotation, and rotation of the motor 4 that moves the optical pickup 1 toward the inner periphery of the disk is referred to as reverse rotation. When the motor 4 is rotated forward, the drive circuit 12 applies a positive drive voltage to the motor 4 when it receives a start signal from the control device 11 to start the motor 4. On the other hand, when a stop signal is received, a negative drive voltage is applied to the motor 4 to apply a brake and stop. When the motor 4 is rotated in the reverse direction, the polarity of the drive voltage is reversed. The drive circuit 12 sends a motor current flowing through the motor 4 to a current detector 13.
[0016]
The current detector 13 detects the magnitude of the motor current supplied from the drive circuit 12 to the motor 4 and sends it to the control device 11 as a motor current signal. The control device 11 determines whether to stop or continue the rotation of the motor 4 according to the motor current detected by the current detector 13.
[0017]
Next, the operation of the optical pickup feed mechanism according to Embodiment 1 of the present invention configured as described above will be described with reference to the waveform diagram shown in FIG.
[0018]
When a disk is inserted into the disk drive device to which the optical pickup feeding mechanism is applied, the control device 11 generates a start signal and sends it to the drive circuit 12 to move the optical pickup 1 to the initial position. The drive circuit 12 generates a positive drive voltage as shown in FIG. 2B and applies it to the motor 4 in response to the start signal. As a result, as shown by a point P1 in FIG. 2A, a positive motor current starts flowing through the motor 4, and the motor 4 starts to rotate forward. Then, while the motor 4 is rotating forward, the motor current continues to maintain the predetermined level.
[0019]
The driving force generated by the forward rotation of the motor 4 is transmitted to the third gear 7 via the first gear 5 and the second gear 6, and rotates the drive shaft 2 fixed to the third gear 7. Accordingly, the optical pickup 1 screwed to the drive shaft 2 moves toward the inner peripheral side of the disk (the direction of arrow A in the drawing) while being guided by the guide shaft 3.
[0020]
In parallel with the mechanical operation described above, the current detector 13 detects the magnitude of the motor current supplied from the drive circuit 12 to the motor 4 and sends the detected magnitude to the control device 11 as a motor current signal. The control device 11 constantly monitors the motor current signal sent from the current detector 13, and drives the start signal while the motor current signal indicates that the motor current is at a predetermined level. Continue to send to circuit 12. As a result, the optical pickup 1 continues to move toward the inner circumference of the disk.
[0021]
As the optical pickup 1 continues to move toward the inner circumference of the disk, the projection 1b of the optical pickup 1 comes into contact with the projection 10b of the base 10 and stops. At this stopped initial position, the optical pickup 1 accurately faces a specific area in the TOC area provided on the inner peripheral side of the disk, that is, the reading start position.
[0022]
As a result of the movement of the optical pickup 1, when the protrusion 1b comes into contact with the protrusion 10b of the base 10, the load on the motor 4 increases. Therefore, the motor 4 starts increasing the motor current as shown at a point P2 in FIG. 2A to generate a larger driving force.
[0023]
When the control device 11 determines that the magnitude of the motor current has exceeded a predetermined threshold α (point P3 in FIG. 2A) by checking the motor current signal from the current detector 13, the control device 11 stops. A signal is generated and sent to the drive circuit 12. As the threshold α, a value larger than the current between the points P1 and P2 in FIG. 2A and smaller than the lock current of the motor 4 can be used.
[0024]
Upon receiving the stop signal, the drive circuit 12 applies a negative pulse-like drive voltage to the motor 4 as shown in FIG. As a result, a negative pulse-like motor current as shown in FIG. 2B flows through the motor 4, and the brake is applied. The width of the negative pulse is appropriately determined in consideration of the time required for the motor 4 to stop rotating. As a result, the positive rotation of the motor 4 is stopped a predetermined time after the generation of the negative pulse-shaped motor current.
[0025]
As described above, according to the optical pickup feed mechanism according to the first embodiment, when the optical pickup 1 moves inward, the projection 1b of the optical pickup 1 comes into contact with the projection 10b of the base 10. As a result, the optical pickup 1 is stopped at the initial position, so that the optical pickup 1 can accurately face a specific area in the TOC area provided on the inner peripheral side of the disk, that is, the reading start position.
[0026]
Further, the fact that the projection 1b of the optical pickup 1 has come into contact with the projection 10b of the base 10 is determined based on the fact that the motor current flowing through the motor 4 has become larger than a predetermined threshold value α. There is no need for a microswitch for detecting a proper innermost position. As a result, the structure of the optical pickup feed mechanism is simplified, and the number of components can be reduced, so that the cost of the optical pickup feed mechanism can be reduced.
[0027]
Next, a modified example of the optical pickup feed mechanism according to the first embodiment of the present invention will be described.
[0028]
A disk drive device to which an optical pickup feed mechanism is applied may be mounted on a vehicle and used. The vehicle is required to be able to operate under a temperature condition of, for example, -30 ° C to + 85 ° C. Therefore, the optical pickup feed mechanism is also required to be able to operate under this temperature condition.
[0029]
Under the above-described temperature conditions, the magnitude of the motor current supplied to the motor 4 varies greatly. Therefore, if the stop or continuation of the rotation of the motor 4 is controlled based on whether the magnitude of the motor current exceeds the above-mentioned threshold α, a situation in which an overcurrent flows through the motor 4 may occur, and May cause a failure.
[0030]
Therefore, in the optical pickup feeding mechanism according to this modification, if the rotation of the motor 4 is stopped by the projection 1b of the optical pickup 1 abutting on the projection 10b of the base 10, the motor current suddenly increases regardless of the ambient temperature. The motor 4 is stopped based on whether or not the rate of change of the motor current exceeds a predetermined threshold value β.
[0031]
That is, if the control device 11 determines that the rate of change of the motor current has exceeded the threshold value β by examining the motor current signal from the current detector 13, it generates a stop signal and sends it to the drive circuit 12. Thus, the driving of the motor 4 is stopped in the same manner as the above-described operation. Note that the rate of change of the motor current can be defined by the value of the motor current increased in a unit time.
[0032]
According to the optical pickup feeding mechanism according to this modified example, it is possible to detect that the projection 1b of the optical pickup 1 has contacted the projection 10b of the base 10 irrespective of the ambient temperature. The used disk drive device can be used even under severe temperature conditions.
[0033]
【The invention's effect】
As described above, according to the present invention, the optical pickup moving toward the inner peripheral side of the disc along the guide shaft fixed to the base so that the axis direction is the radial direction of the disc comes into contact with a part of the base. The optical pickup can be stopped at the initial position with high accuracy because the optical pickup is stopped at the stopped position and faces the reading start position provided on the inner peripheral side of the disk at the stopped position. There is an effect that an inexpensive optical pickup feeding mechanism having a structure can be provided.
[Brief description of the drawings]
FIG. 1 is a plan view schematically showing a configuration of an optical pickup feed mechanism according to Embodiment 1 of the present invention.
FIG. 2 is a waveform chart for explaining an operation of the optical pickup feed mechanism according to the first embodiment of the present invention.
[Explanation of symbols]
Reference Signs List 1 optical pickup, 2 drive shaft (drive mechanism), 3 guide shaft, 4 motor (drive mechanism), 5 first gear (drive mechanism), 6 second gear (drive mechanism), 7 third gear (drive mechanism), 8, 9 bearing (drive mechanism), 10 base, 10a opening, 10b protrusion, 11 control device, 12 drive circuit, 13 current detector.

Claims (3)

An optical pickup that reads information from a disc,
A guide shaft fixed to the base such that the direction of the shaft is in the radial direction of the disc,
A drive mechanism for moving the optical pickup along the guide axis,
When the optical pickup is moved to the inner peripheral side of the disk by the driving mechanism, the optical pickup comes into contact with a part of the base and stops, and the reading provided on the inner peripheral side of the disk at the stopped position. An optical pickup feed mechanism characterized by being opposed to the start position. The drive mechanism includes:
A drive shaft for moving the optical pickup along the guide shaft,
A motor for driving the drive shaft;
A current detector for detecting a motor current flowing through the motor,
When the motor is started, the optical pickup is moved to the inner peripheral side of the disc to make contact with the base, and when the magnitude of the motor current detected by the current detector becomes equal to or greater than a predetermined value, 2. The optical pickup feed mechanism according to claim 1, further comprising a control device for stopping the motor. A drive shaft for moving the optical pickup along the guide shaft,
A motor for driving the drive shaft;
A current detector for detecting a motor current flowing through the motor,
When the motor is started, the optical pickup is moved toward the inner circumference of the disk and is brought into contact with the base, and when the rate of change of the motor current detected by the current detector becomes a predetermined value or more, the motor is started. The optical pickup feed mechanism according to claim 1, further comprising a control device for stopping the optical pickup.

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