JPH0770060B2 - Optical head transfer device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical head transfer device for recording, reproducing or erasing information on an information track formed on a recording medium.

2. Description of the Related Art Japanese Unexamined Patent Publication No. 61-42741 discloses a structure for guiding the movement of a movable portion of an optical head including a guide shaft having a bearing loss and an objective lens for focusing on an information track of a recording medium without using a bearing. Optical head transfer device has been proposed. This prior art will be described below with reference to FIG.

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

In FIG. 5, the X direction is the direction orthogonal to the information track of the recording medium (called the tracking direction), the Z direction is the direction perpendicular to the recording medium (called the focus direction), the Y direction is the X direction, The direction is perpendicular to both the Z direction and the tangential direction of the information track of the recording medium.

Reference numeral 131 denotes a reflecting mirror, which is adjusted so that the optical axis of the objective lens 107 is reflected along the optical path C of the optical disc 101 in the X direction, and is fixed to the carriage 133. 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 optical axis direction to focus. The carriage 133 having such a structure is directly connected to the movable shaft 134 integrally formed with the moving coil 135 of the voice coil motor 106, and the movable shaft 134 is connected to the voice coil via a leaf spring 136 having flexibility in the X direction. Spacer screws 138 are used at the fixed portion 137 of the motor 106 to support the motor 106 at two positions in the front and rear. A magnetic circuit 139 can position the carriage 133 on the medium surface of the optical disc 101 in the X direction by supplying a control current to the moving coil 135. Even if the carriage 133 moves, since the moving direction matches the optical path C, the optical axis does not move, and the reflecting mirror 132 can guide the light in a desired direction.

Further, the structure and operation of the optical system housed in the fixed portion of the optical disk device main body is that the laser light emitted from the laser diode 112 of the light source becomes a parallel light beam by the collimator lens 113 and becomes a circular light flux by the perfect circle correction prism 114. The light beam spot is adjusted, passes through the polarization beam splitter 115 and the λ / 4 plate 116 (λ is the wavelength of the laser beam), is condensed into a light beam spot by the objective lens 107, and is irradiated onto the track of the optical disc 101.

Further, the reflected light from the optical disc 101 travels backward in the incident optical path, is reflected at a right angle by the polarization beam splitter 115, and is received by the photodetector 119 via the cylindrical lens 117 and the condenser lens 118. ing.

In addition to this, the optical system also houses a detection circuit 120 such as a focus detection system, a track position detection system, and a signal detection system.

As described above, according to the conventional optical head transfer device,
It is possible to improve the reliability of the apparatus by guiding the movable portion of the optical head by means of the leaf spring 136 having flexibility in the X direction without using a guide shaft and bearing having bearing loss.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, in the above, the voice coil motor 106 and the automatic focus control mechanism 108 exist independently of each other, and the automatic focus control mechanism 108 is assumed to be the most general-purpose voice coil motor. If such a configuration is adopted, the voice coil motor 106 and the automatic focus control mechanism 108 require separate magnetic circuits, and the optical head becomes large, and thus the optical head transfer device equipped with this optical head also becomes large. Had.

In view of the above point, the present invention uses a magnetic circuit common to a voice coil motor that drives an objective lens in a direction perpendicular to a recording medium to move a movable portion of an optical head in a direction orthogonal to an information track of the recording medium, Moreover, it is an object of the present invention to provide an optical head transfer device that has a small number of parts, has a simple and inexpensive structure, and can be downsized. Further, it is possible to provide an optical head transport device which is free from bearing loss in a device including a guide shaft and a bearing, that is, has no friction and wear and is highly reliable.

Means for Solving the Problems In order to solve the above problems, the present invention relates to an optical head transport device, an objective lens for condensing a light beam on an information track of a recording medium, and a mover bobbin accommodating the objective lens. A carriage that movably supports the mover bobbin at least in a direction perpendicular to the recording medium, and a focus coil that is provided on the mover bobbin and drives the objective lens in a direction perpendicular to the recording medium. A tracking coil that is provided on at least one of the mover bobbin and the carriage and that drives at least the carriage in a direction orthogonal to the information track, and a magnet that supplies magnetic flux to the focus coil and the tracking coil to generate a driving force. A circuit and a plate bar for movably supporting the carriage in a direction orthogonal to the information track. The magnetic circuit has yokes on both sides in a tangential direction of the information track of the carriage, the yoke being longer than a width of the carriage in the orthogonal direction of the information track, and at least one of the yokes. A magnet is provided on the yoke, and the leaf spring has a notch for penetrating the yoke, a first fixing portion for fixing to the carriage, and a second fixing portion for fixing to a magnetic circuit around the notch. It is configured.

Action The present invention has the above-described configuration, has a small number of parts, and can be made simple and inexpensive to downsize the optical head transfer device. Further, since the device is not configured to be supported by the guide shaft and the bearing, reliability without friction and wear is provided. It is possible to provide a high device.

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

1 to 4, the X direction is a direction orthogonal to the information track of the recording medium (called a tracking direction), the Z direction is a direction perpendicular to the recording medium (called a focusing direction), and the Y direction. Is a direction perpendicular to both the X direction and the Z direction, and is a tangential direction of the information track of the recording medium.

Hereinafter, this embodiment will be described with reference to FIGS. 1 to 4.

Reference numeral 1 is a recording medium, which is an optical disc having spiral or concentric information tracks. An optical disk motor 2 is a motor for mounting the recording medium 1 and rotating the same. A fixed optical unit 3 includes a semiconductor laser as a light source and a recording medium 1.
The fixing member accommodates a detector for detecting the reflected light from the optical disk, an optical element such as a prism for converting the light beam from the semiconductor laser into parallel light, and the like. An objective lens 4 focuses the light beam on the recording medium 1. Reference numeral 5 denotes a bobbin as a mover, which houses the objective lens 4 on the side of the recording medium 1 in the Z direction, and is wound with two focus coils 5a for driving the objective lens 4 in the Z direction and two tracking coils 5b for driving the X direction. There is. Reference numeral 6 denotes a balance weight, which is housed at a position opposite to the recording medium 1 in the Z direction of the mover bobbin 5, that is, a position facing the objective lens 4 in order to maintain the dynamic balance of the mover bobbin 5. 7 is an objective lens supporting means,
A three-layer sandwich structure of a focus leaf spring in which the central cylindrical portion 7a and the peripheral portion 7b are connected in a spiral shape, a damping rubber that damps resonance of the focus leaf spring, and an auxiliary spring that reinforces the peripheral portion 7b is provided. One is that the central cylindrical portion 7a is adhered and fixed to the outer peripheral portion of the cylindrical portion of the mover bobbin 5 that houses the objective lens 4, and the other similarly accommodates the balance weight 6 of the mover bobbin 5. The central cylindrical portion 7a is adhesively fixed to the outer peripheral portion of the cylindrical portion. 7c
Is a positioning hole for adhering and fixing the peripheral portion 7b to the carriage 8 described later, one is a round hole and the other is a long hole. Reference numeral 8 denotes a carriage, which is a peripheral portion 7b of the two objective lens supporting means 7.
Are bonded and fixed on the surface on the recording medium 1 side in the Z direction and the surface on the opposite side. Reference numeral 8a is a positioning boss for bonding the peripheral portion 7b of the objective lens supporting means 7. Also, 8b
Is a positioning boss for positioning a leaf spring 11 described later. Reference numeral 9 denotes a reflection mirror, which is a mirror for reflecting the light beam emitted from the fixed optical unit 3 in the X direction in the Z direction. Reference numeral 10 is a reflection mirror holder, and the reflection mirror 9 is adhesively fixed to the carriage 8. In addition, 10a
Like 8b, is a positioning boss for positioning a leaf spring 11 described later. A leaf spring 11 is positioned and adhered by the positioning hole 11a and the positioning boss 8b of the carriage 8 or the positioning boss 10a of the reflection mirror holder 10, and is screwed and fixed by the hole 11b and a screw hole 12a of the plate spring holder 12 described later. When the transfer force acts on the carriage 8, the deformable portion 11c is deformed to support the carriage 8 linearly in the X direction. 12 is a leaf spring holder with screw holes
The leaf spring 11 is screwed and fixed by 12a and the hole 11b of the leaf spring 11. The hole 12b is a hole for screwing and fixing to a back yoke 14 described later. Reference numeral 13 denotes a magnet, which includes a back yoke 14, a facing yoke 15, and a side yoke A1 which will be described later.
6, a magnetic circuit is constructed with the side yoke B17, the mover bobbin 5 is driven in the Z direction by the electromagnetic force with the focus coil 5a, and the carriage 8 and the mover bobbin 5 are moved in the X direction by the electromagnetic force with the tracking coil 5b. To drive. 14
Is a back yoke, which is made of electromagnetic soft iron and to which the magnet 13 is adhered and fixed. The leaf spring holder 12 is screwed and fixed by the screw hole 14a and the hole 12b of the leaf spring holder 12. A facing yoke 15 is formed of electromagnetic soft iron and is arranged at a position facing the magnet 15. 16 is a side yoke A, which is made of electromagnetic soft iron,
The back yoke 14 and the opposing yoke 15 are fixed at the tips. Reference numeral 16a is a hole for screwing and fixing to the main body (not shown) of the optical recording or reproducing apparatus. Further, 16b is a fixed optical unit mounting portion, which has two holes for fixing the fixed optical unit 3, one of which is a set screw and a standard hole without backlash, and the other of which is a hole larger than the set screw. It is designed so that it can be tilted and fixed with screws. Reference numeral 17 denotes a side yoke B, which is made of electromagnetic soft iron and fixes the back yoke 14 and the counter yoke 15 at their tips. Like 17a, 17a is a hole for screwing and fixing to the main body (not shown) of the optical recording or reproducing apparatus. 18 is a fixed optical unit support spring, which is a side yoke A1
It is an L-shaped leaf spring for connecting and fixing 6 and the fixed optical unit 3. That is, the fixed optical unit 3 is fixed at two positions with sufficient distance, that is, the side yoke A, the fixed optical unit mounting portion 16b, and the fixed optical unit support spring 18, and has a stable fixing structure against vibrations and shocks. There is.

In addition, the focus coil 5a and the tracking coil 5b
The movable part which is moved by the driving force generated in is mainly composed of two movable parts. The first is the movable part A
The objective lens supporting means 7 supports the objective lens 4, the balance weight 6, the mover bobbin 5, the focus coil 5a, and the tracking coil 5b to form a unit. The second is the movable part B, which is a leaf spring 11
Is a unit which is integrally supported by the reflection mirror 9, the carriage 8 and the reflection mirror holder 10.

The movable part A and the movable part B are tracking coils.
In the state where no driving force is generated in 5b, as shown in FIG.
It is arranged in the middle position.

The operation of the optical head transporting device of this embodiment having the above-described configuration will be described below.

First, when a drive current flows through the focus coil 5a, a drive force is generated in the Z direction by the electromagnetic action with the magnetic circuit in the focus coil 5a. At this time, since the spiral portion of the objective lens supporting means 7 that supports the movable portion A with respect to the movable portion B is sufficiently soft in the Z direction, the spiral portion of the objective lens supporting means 7 is deformed, so that the movable portion A becomes Z. Move in the direction.

On the other hand, when a driving current flows through the tracking coil 5b, a driving force is generated in the X direction by the electromagnetic action with the magnetic circuit in the tracking coil 5b. At this time, the tracking coil up to the resonance frequency (around 1 KHz) of the objective lens supporting means 7 in the X direction which is determined by the rigidity of the spiral portion of the objective lens supporting means 7 in the X direction and the mass of the movable portion A and the movable portion B. The driving force generated in 5b is also transmitted to the movable part B through the objective lens supporting means 7, but at a frequency higher than this resonance frequency, the objective lens supporting means 7 is substantially equivalent to that which does not exist, and tracking is performed. The driving force generated in the coil 5b is not transmitted to the movable portion B. That is, with respect to the X direction, the movable portion changes at the boundary of the resonance frequency of the objective lens support means 7 in the X direction, and this resonance frequency is referred to as split resonance. Therefore, both the movable portion A and the movable portion B vibrate up to the frequency of the split resonance, and only the movable portion A vibrates at the frequency after the split resonance.

Further, when the movable part B is moved at a frequency lower than the split resonance, the movement of the leaf spring 11, which is the supporting member thereof, is deformed in the form shown by the broken line and the alternate long and short dash line in FIG. That is, the movable part B and the movable part A can be linearly moved in the X direction. At this time, the driving force generated in the tracking coil 5b and the restoring force of the leaf spring 11 balance each other.

Therefore, when recording, reproducing or erasing information on any information track of the recording medium 1, a driving current for generating a driving force corresponding to the restoring force of the leaf spring 11 at that time is applied to the tracking coil 5b in a direct current manner. All you have to do is add.

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

Further, in this embodiment, the transfer device of the separation type optical head in which the optical head is separated into the fixed optical unit and the movable optical unit has been described, but the integrated type optical head configured to transfer the entire optical head is described. The head is also effective.

Further, in the present embodiment, as shown in FIG. 3, the deformed portions of the leaf spring 11 are provided at two locations on both sides of the movable portion B and the movable portion A in the Y direction. Y
Two deformed portions may be provided on one side of the direction and one deformed portion on the other side.

EFFECTS OF THE INVENTION As described above, according to the present invention, the number of parts is small, the optical head transfer device can be downsized in a simple and inexpensive manner, and the device is not configured to be supported by the guide shaft and the bearing. -It is possible to provide a highly reliable optical head transfer device without wear.

Further, by providing the deformed portions of the leaf springs on both sides of the movable portion, the movable portion can be linearly moved, and the information track of the recording medium and the moving locus of the movable portion can always be made orthogonal to each other.
This is because, in the transfer device of the separation type optical head in which the optical head is separated into the fixed optical unit and the 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 portion are transferred. It is particularly effective because the locus and the locus should match as closely as possible.

[Brief description of drawings]

1 to 4 show an embodiment of the present invention, FIG. 1 is an exploded perspective view, FIGS. 2 (a) and 2 (b) are a top view and an AA ′ sectional view, and FIG. 3 ( FIGS. 4A and 4B are a top view and a front view of a main part, FIG. 4 is a sectional view taken along the line BB ′, and FIG. 5 is a perspective view of a conventional optical head transfer device. 1 ... Recording medium, 4 ... Objective lens, 5 ... Movable bobbin, 5a ... Focus coil, 5b ... Tracking coil, 7 ... Objective lens supporting means, 8 ... Carriage, 9
...... Reflecting mirror, 11 ...... Leaf spring, 13,14,15,16,17 …… Magnetic circuit.

Claims (1)

[Claims] 1. An objective lens for focusing a light beam on an information track of a recording medium, a mover bobbin accommodating the objective lens, and a movable bobbin movably supported at least in a direction perpendicular to the recording medium. And a focus coil provided on the mover bobbin for driving the objective lens in a direction perpendicular to the recording medium, and provided on at least one of the mover bobbin and the carriage, and at least the carriage is provided with the information. A tracking coil that drives in the direction orthogonal to the track, a magnetic circuit that supplies a magnetic flux to the focus coil and the tracking coil to generate a driving force, and a leaf spring that movably supports the carriage in the direction orthogonal to the information track. The magnetic circuit is connected to the information track of the carriage. There are yokes on both sides in the line direction, the yoke is longer than the width of the carriage in the direction orthogonal to the information track, and at least one yoke is provided with a magnet. An optical head transfer device, comprising: a notch to be penetrated, a first fixing part to be fixed to a carriage, and a second fixing part to be fixed to a magnetic circuit, around the notch.