JPH0266742A - Optical head shifting device - Google Patents

Abstract

PURPOSE:To shift the movable part of an optical head in the direction orthogonal to the track of a recording medium by using a magnetic circuit common to a voice coil motor to drive an objective lens in the direction vertical to the recording medium. CONSTITUTION:When a driving current flows at a focus coil 5a, a driving force occurs in a Z direction by the electromagnetic action with a magnetic circuit at a coil 5a. Thus, a movable part A composed of an objective lens 4, a needle bobbin 5, an objective lens supporting means 7 or the like is moved in a Z direction. On the other hand, when a driving current flows at a tracking coil 5b, a driving force occurs in an X direction by the electromagnetic action with a magnetic circuit at the coil 5b. Thus, up to the frequency of the dividing resonance, both movable part A and movable part B composed of a carriage 8, a reflecting mirror 9, a plate spring 11 or the like are oscillated. When the movable part B is moved by the frequency lower than the dividing resonance, the plate spring 11, which is the supporting member, is deformed and the movable part B and the movable part A can be linearly shifted in an X direction.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an optical head transport device for recording, reproducing, or erasing information on information tracks formed on a recording medium.

Conventional technology Japanese Patent Application Laid-Open No. 61-42741 discloses a configuration for guiding the movement of a movable part of an optical head including a guide shaft having bearing loss and an objective lens that focuses light on an information track of a recording medium without using a bearing. An optical head transfer device has been proposed. This conventional technique will be explained below using FIG. 5.

FIG. 5 is a perspective view of a conventional optical head transfer device.

In FIG. 5, the X direction is the direction perpendicular to the information 1-rank of the recording medium (referred to as the tracking direction), the X direction is the direction perpendicular to the recording medium (referred to as the focus direction), and the Y direction is the This is a direction perpendicular to both the X direction and the X direction, and is a tangential direction to the information track of the recording medium.

A reflecting mirror 131 is fixed to the carriage 133 and is adjusted so as to reflect the optical axis of the objective lens 107 along an optical path C in the X direction of the optical disc 101.

An automatic focus control mechanism 108 is provided on the upper surface of the carriage 133, and the objective lens 107 is finely adjusted in the direction of its optical axis to focus. The carriage 133 having such a configuration is directly connected to a movable shaft 134 that is integrally constructed with the moving coil 135 of the voice coil motor 106, and the movable shaft 133 is
4 is supported at three locations in the front and rear using spacer screws 138 on a fixed portion 137 of the voice coil motor 106 via a plate spring 136 having flexibility in the X direction. Reference numeral 139 denotes a magnetic circuit that can position the carriage 133 on the medium surface of the optical disk 101 in the X direction by supplying a control current to the moving coil 135. Even if the carriage 133 moves, the moving direction matches the optical path C, so there is no deviation of the optical axis, and the reflecting mirror 132 can guide the light in a desired direction.

The configuration and operation of the optical system housed in the fixed part of the optical disk device main body are based on the laser diode 1-'1)2 of the light source.
The laser beam emitted from the collimator lens 1) 3 converts the laser beam into a parallel beam, and the circular correction prism 1) 4 adjusts the beam into a circular beam.
The light passes through 4 plates 1) 6 (λ is the wavelength of the laser beam) and is focused on the optical beam spot by the objective lens 107, and is focused on the optical disk 101.
is illuminated onto the track.

In addition, the reflected light from the optical disk 101 travels backward along the incident optical path, is reflected at right angles by the polarizing beam mirror 1) 5, passes through the cylindrical force lens 1) 7 and the condensing lens 1) 8, and then passes through the photodetector 1). The light is received at 9.

Furthermore, the optical system also houses detection circuits 120 such as a focus detection system, a track position detection system, and a signal detection system.

As explained above, according to the conventional optical head transfer device,
The reliability of the apparatus can be improved by guiding the movable part of the optical head using a plate spring 136 that is flexible in the X direction without using a guide shaft and bearings that have bearing loss.

Problem to be Solved by the Invention However, in the above-mentioned device, the voice coil motor 106 and the automatic focus control mechanism 108 exist independently of each other, and it is assumed that the automatic focus control mechanism 108 is replaced with the most general-purpose voice coil motor. If configured as shown in FIG.

In view of this, the present invention uses a common magnetic circuit with a voice coil motor that drives an objective lens in a direction perpendicular to the recording medium to move the movable part of the optical head in a direction perpendicular to the information track of the recording medium, Moreover, it is an object of the present invention to provide an optical head transfer device having a simple and inexpensive configuration with a small number of parts.

Means for Solving the Problems The present invention provides an objective lens that focuses an optical beam onto an information track of a recording medium, a movable bobbin that integrally houses the objective lens, and a movable bobbin that is integrally wound on the movable bobbin. A focus coil for driving the objective lens in a direction perpendicular to the recording medium, an objective lens support means for movably supporting the movable bobbin at least in a direction perpendicular to the recording medium, and the objective lens support means. a carriage configured integrally with a fixed portion of the movable bobbin or the carriage;
a tracking coil that drives at least the carriage in a direction perpendicular to the information track; and a plate that is connected to the carriage and a fixed part of the optical recording/reproducing device and supports the carriage movably in the direction perpendicular to the information track. The optical head transport device includes a spring and a magnetic circuit that commonly supplies magnetic flux to both the focus coil and the tracking coil to generate a driving force.

Operation The present invention has a simple and inexpensive structure with a small number of parts, and uses a magnetic circuit common to the voice coil motor that drives the objective lens in a direction perpendicular to the recording medium to drive the movable part of the optical head. It can be transported in a direction perpendicular to the information tracks of the recording medium.

EXAMPLE An example of the present invention will be described below with reference to the drawings. 1 to 4 show an embodiment of the present invention,
Figure 1 is an exploded perspective view, Figure 2 is a top view and A-A
3 is a top view and a front view of the main part, and FIG. 4 is a BB' sectional view.

In Figures 1 to 4, the X direction is a direction perpendicular to the information track of the recording medium (referred to as the tracking direction), the X direction is the direction perpendicular to the recording medium (referred to as the focus direction), and the Y direction is the direction perpendicular to both the X direction and the direction tangential to the information track of the recording medium.

This embodiment will be described below using FIGS. 1 to 4.

Reference numeral 1 denotes a recording medium, which is an optical disk having spiral or concentric information tracks. 2 is a disk motor that rotates the recording medium 1. 63 is a fixed optical unit that includes a semiconductor laser as a light source, a detector that detects the reflected light from the recording medium 1, and a light beam from the semiconductor laser. An optical element such as a prism that converts light into parallel light is housed in a fixed member. Reference numeral 4 denotes an objective lens that focuses a light beam onto the recording medium 1. 5 is a movable bobbin,
The objective lens 4 is housed on the recording medium 1 side in the X direction, and two focus coils 5a and X
Two tracking coils 5b which are driven in the direction are wound. A balance weight 6 is housed at a position opposite to the recording medium 1 in the X direction of the movable bobbin 5, that is, at a position facing the objective lens 4, in order to dynamically balance the movable bobbin 5. 7 is an objective lens support means;
The three-layer sandwich structure includes a focus plate spring in which a central cylindrical part 7a and a peripheral part 7b are connected in a spiral shape, a damping rubber that dampens the resonance of this focus plate spring, and an auxiliary spring that reinforces the peripheral part 7b. and
One has a central cylindrical part 7a adhesively fixed to the outer periphery of a cylindrical part that houses the objective lens 4 of the movable bobbin 5, and the other one has the outer periphery of a cylindrical part that similarly houses the balance weight 6 of the movable bobbin 5. A central cylindrical portion 7a is adhesively fixed to the center cylindrical portion 7a. In addition, 7C is a positioning hole when adhesively fixing the peripheral part 7b to the carriage 8 mentioned later, one is a round hole and the other is a long hole. Reference numeral 8 denotes a carriage, and the peripheral portions 7b of the two objective lens support means 7 are adhesively fixed to the surface of one example of the recording medium in the X direction and the surface on the opposite side thereof. Note that 8a is a positioning boss for bonding the peripheral portion 7b of the objective lens support means 7. Moreover, 8b is a positioning boss for positioning a leaf spring 1), which will be described later. Reference numeral 9 denotes a reflecting mirror, which reflects in the X direction the light beam emitted from the fixed optical unit 3 in the X direction. Reference numeral 10 denotes a reflective mirror holder to which the reflective mirror 9 is fixed with adhesive and is fixed to the carriage 8 with adhesive. Note that, like 8b, 10a is a positioning boss for positioning a leaf spring 1), which will be described later. 1) is a plate spring, which is positioned and glued by the positioning hole 1)a and the positioning boss 8b of the carriage 8 or the positioning boss 10a of the reflective mirror holder 10; The carriage 8 is fixed with screws, and whenever a transfer force is applied to the carriage 8, the deformable portion 1) deforms, thereby supporting the carriage 8 so as to be movable linearly in the X direction. Reference numeral 12 denotes a leaf spring holder, which fixes the leaf spring 1) with screws through a screw hole 12a and a hole 1)b of the leaf spring 1). Note that the hole 12b is a hole for fixing with a screw to a hack yoke 14, which will be described later. 13
is a magnet, which constitutes a magnetic circuit together with a hack yoke 14, an opposing yoke 15, a side yoke A 16, and a side yoke B 17, which will be described later.The movable hobbin 5 is driven in the X direction by electromagnetic force with the focus coil 5a, and the tracking coil 5b and The carriage 8 and movable bobbin 5 are driven in the X direction by the electromagnetic force. A hack yoke 14 is made of electromagnetic soft iron, and the magnet 13 is fixed with adhesive. Note that the screw hole 14a and the plate spring holder 12
The plate spring holder 12 is fixed by screws through the hole 12b. Reference numeral 15 denotes a facing yoke, which is made of electromagnetic soft iron and is disposed at a position facing the magnet 15.

1G is a side yoke A made of electromagnetic soft iron, and fixes the hack yoke 14 and the opposing yoke 15 at its tips. Note that 16a is a hole for fixing to the main body of the recording/reproducing apparatus (not shown) with a screw. In addition, 16b is a fixed optical unit/nod attachment part, which has two holes for fixing the fixed optical unit 3, one of which is a reference hole that does not have any play with a set screw, and the other is a hole that is larger than the set screw, and has two holes for fixing the fixed optical unit 3. It is designed to be fixed with screws so that the inclination around it can be adjusted.

A side yoke B 17 is made of electromagnetic soft iron and fixes the hack yoke 14 and the opposing yoke 15 at its tips. Note that, like 16a, 17a is a hole for screwing and fixing to the main body of the recording/reproducing apparatus (not shown). 18
A fixed optical unit support spring is a glue-shaped plate spring for connecting and fixing the side yoke A16 and the fixed optical unit 3. That is, the fixed optical unit 3 is fixed at three sufficiently distant locations: the side yoke A, the fixed optical unit mounting portion 16b, and the fixed optical unit support spring 18, and a stable fixed structure against vibrations, shocks, etc. is achieved. There is.

Further, the movable section that is moved by the driving force generated in the focus coil 5a and the tracking coil 5b is mainly composed of two movable sections. The first is a movable unit that is supported by objective lens support means 7 and is integrally constituted by objective lens 4, balance way l-6, mover Bohin 5, focus coil 5a, and tracking coil 5b. . The second is the moving part B,
It is a unit that is supported by a plate spring 1) and is integrally constituted by a counter mirror 9, a carriage 8, and a reflective mirror holder 10.

In addition, when no driving force is generated in the tracking coil 5b, the J section A and the movable section B are located at the center of the magnetic circuit in the X direction, that is, the middle circumference of the recording medium 1, as shown in Figure 3 of the book. It is located in

The operation of the optical head transfer device of this embodiment configured as described above will be explained below.

First, when a drive current flows through the focus coil 5a, a drive force is generated in the focus coil 5a in the X direction due to electromagnetic interaction with the magnetic circuit. At this time, the spiral portion of the objective lens support means 7 that supports the movable part A with respect to the movable part B is
Since it is sufficiently flexible in terms of direction, the objective lens support means 7
The movable part A moves in the X direction by deforming the spiral part.

On the other hand, when a drive current flows through the tracking coil 5b,
A driving force is generated in the X direction in the tracking coil 5b due to electromagnetic interaction with the magnetic circuit.

At this time, the resonance frequency in the X direction of the objective lens support means 7 (around IKHz) is determined by the rigidity in the X direction of the spiral portion of the objective lens support means 7 and the mass of the entire movable part A supported by the objective lens support means 7. Up to this point, the driving force generated in the tracking coil 5b is also transmitted to the movable part B via the objective lens support means 7, or at frequencies higher than this resonance frequency, the objective lens support means 7 is substantially absent. They are equivalent, and the driving force generated in the tracking coil 5b is not transmitted to the movable part B. That is, regarding the X direction, the movable portion changes with the X direction resonance frequency of the objective lens support means 7 as a boundary, and this resonance frequency will be referred to as split resonance. Therefore, up to the frequency of split resonance, both movable part A and movable part B vibrate, and at frequencies after split resonance, only movable part A vibrates.

Further, when the movable part B is moved at a frequency lower than the split resonance, the movement of the leaf spring 1), which is a supporting member thereof, is deformed as shown by the broken line and the dashed-dotted line in FIG. That is, movable part B and movable part A can be moved linearly in the X direction. At this time, the driving force generated in the tracking coil 5b and the restoring force of the leaf spring 1) are balanced.

Therefore, when recording, reproducing, or erasing any information on the recording medium 1, the leaf spring 1 at that time
) A drive current that generates a drive force corresponding to the restoring force of 2 is applied to the tracking coil 5b in a direct current manner.

In this embodiment, the tracking coil 5b is integrally provided only on the movable bobbin 5, but it may be provided integrally only on the carriage, or it may be provided integrally on both the carriage and the movable bobbin. You can.

In addition, in this embodiment, a separate type optical head transfer device was described in which the optical head was separated into a fixed optical unit and a movable optical unit, but an integrated optical head configured to transfer the entire optical head was described. This is also effective for heads.

In addition, in this embodiment, as shown in FIG. 3, two deformable parts of the leaf spring 1) are provided on both sides of the movable part B and the movable part A in the Y direction. Deformed portions may be provided at three locations on one side in the Y direction and at one location on the other side.

As described in detail, the present invention has a simple and inexpensive configuration with a small number of parts, and uses a magnetic circuit common to the voice coil motor that drives the objective lens in a direction perpendicular to the recording medium. The movable part of the optical head can be moved in a direction perpendicular to the information track of the recording medium.

Furthermore, by providing the deformable parts of the leaf springs on both sides of the movable part, the movable part can be moved linearly, and the information track of the recording medium and the moving locus of the movable part can always be perpendicular to each other.

In a separate type optical head transfer device in which the optical head is separated into a fixed optical unit and a movable optical unit as in this embodiment, the optical axis of the light beam emitted from the fixed optical unit and the transfer of the movable part are This is particularly effective because it is better to match the trajectory as much as possible.

[Brief explanation of the drawing]

1 to 4 show one embodiment of the present invention, in which FIG. 1 is an exploded perspective view, FIG. 2 (al fbl is a top view and A-A' sectional view, and FIG. 4 is a sectional view taken along line B-B', and FIG. 5 is a perspective view of a conventional optical head transport device. ■ Recording medium, 4... ...objective lens,
5... Mover bobbin, 5a... Focus coil, 5b... Tracking coil, 7
...Objective lens support means, 8...Carriage, 9...Reflection mirror, 1)...
Leaf spring, 13.14.15.16.17...Magnetic circuit. Name of agent: Patent attorney Shigetaka Awano

Claims (2)

[Claims] (1) an objective lens that focuses a light beam onto an information track of a recording medium; a movable bobbin that integrally houses the objective lens; A focus coil driven in a direction perpendicular to the medium, an objective lens support means for movably supporting the movable bobbin at least in a direction perpendicular to the recording medium, and a fixed part of the objective lens support means integrally configured. a tracking coil that is integrally disposed on at least one of the movable bobbin or the carriage and drives at least the carriage in a direction perpendicular to the information track; and fixing of the carriage and the optical recording/reproducing device. a plate spring connected to the section and movably supporting the carriage in a direction orthogonal to the information track; and a magnetic circuit that commonly supplies magnetic flux to both the focus coil and the tracking coil to generate a driving force. An optical head transfer device comprising: (2) The leaf spring has at least one deformable portion on each side of the carriage in the direction orthogonal to the information track, which can be deformed in a direction perpendicular to the information track by a driving force generated in the tracking coil. An optical head transfer device according to claim (1).