JPH0636320A - Optical head device and optical disk device including the device - Google Patents

Abstract

(57) [Abstract] [Purpose] To increase the rigidity of a base that is a base on which parts such as an objective lens are mounted, and to reduce the size and thickness of an optical head device and an optical disk device. [Arrangement] An optical head device comprising an optical head including a base 17 made of a glass material having an L-shape in a side view and a lens barrel 8 having a reflection mirror 9 and an objective lens 7 and a moving means thereof. The laser light emitted from the fixed optical system 20 is irradiated, and the laser light is guided to the objective lens 7 which is transmitted through the glass base 17 and reflected by the reflection mirror 9, and the objective lens 1 collects the reflected light. Then, a light spot is formed on the recording surface of the disc 1 to record / reproduce information.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical head device used for information equipment and AV equipment such as a magneto-optical disk and a compact disk, and an optical disk device equipped with the same.

[0002]

2. Description of the Related Art Conventionally, as an optical disk device of this type,
There is a technique described in JP-A-2-123544. Figure 8
3, reference numeral 3 is a base having an L-shaped vertical section with rolling bearings 2 and 2 for moving in the radial direction of a disc 1 which is an information recording medium. One end of each of the piezoelectric elements 6 and 6 is attached, and the lens barrel 8 holding the objective lens 7 is held at the other end. On the horizontal wall 5 of the base 3, a reflection mirror 9 having a triangular shape in a side view is fixed vertically below the objective lens 7. A through hole 10 for entering laser light is formed at a predetermined position on the vertical wall 4 on the light entrance side of the reflection mirror 9. Then, the laser light emitted from the light source passes through the through hole 10 formed in the vertical wall 4 of the base 3, is reflected by the reflection mirror 9, and is guided to the objective lens 7. The laser light guided by the reflection mirror 9 is condensed by the objective lens 7, and the light spot is irradiated onto the surface of the disc 1.

US Pat. No. 4,823,336 describes the following optical head device. As shown in FIG. 9, first, bobbins 13 and 13 having coils 12 formed by windings are mounted on both side surfaces of the carriage 11, and guide shafts 14 and 14 are provided in through holes of the bobbins 13 and 13. Has been inserted. Further, the bobbin 13 parallel to both side surfaces of the carriage 11,
C-shaped outer motor yoke 15, 15 so as to cover the side surface of 13.
Are mounted on the guide shafts 14, 14. Furthermore, the magnets 16, 16
Are mounted on the surfaces of the outer motor yokes 15, 15 where the coils 12, 12 face each other.

[0004]

In recent years, information equipment and AV
As devices become smaller, lighter, and thinner, it is desired that parts or units that make up such devices also be made smaller and thinner.

The above-mentioned conventional example, Japanese Patent Laid-Open No. 123544/1990.
In the technique described in the publication, since a material that does not transmit light is used for the base, it is necessary to form a through hole in the light passage portion of the base. As a result, the rigidity of the base is reduced, while the base itself is large due to the size of the through hole. Furthermore, since the base and the reflection mirror are separate members, the size of the apparatus becomes large, and further, the accuracy of mounting the reflection mirror is required.

Further, although the base material is conventionally made of metal such as aluminum, the weight is still heavy and the seek movement speed becomes slow. Further, since the Young's modulus is small, the rigidity of the head could not be increased.

An object of the present invention is to solve the above problems and provide an optical head device and an optical disk device which have been made smaller and lighter, thinner, and more rigid.

[0008]

In order to achieve such an object, according to the present invention, a base of an optical head device is formed of a light transmissive material, and a laser beam is irradiated to a deflecting means through a part of the base. It will be configured.

Further, the optical disk device is provided with the optical head device having the above-mentioned structure.

[0010]

As described above, the use of the light transmitting material for the base of the optical head device allows the laser light from the fixed optical system to pass through the base. No through hole is required, and the rigidity of the base is increased. In addition, since the rigidity of the base is increased, unnecessary vibration is less likely to occur in the base, and accurate seek operation can be performed.

Further, since the optical head device can perform an accurate seek operation, the track density of the optical disk can be increased.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings. The same members as those in the conventional technique are designated by the same reference numerals.

In FIG. 1, 1 is a disk which is an information recording medium, 2 is a bearing, 6 is a piezoelectric element, 7 is an objective lens, 8 is a lens barrel, 9 is a reflection mirror, 17 is a base, 18 is a vertical wall, and 19 is a vertical wall. Is a horizontal wall, and 20 is a fixed optical system.

The optical head device according to the first embodiment is shown in FIG.
In the structure described in the related art, the base 3 is made of a glass material, and the through hole 10 for light transmission provided in the vertical wall 4 of the base 3 is eliminated.

That is, as shown in FIG. 1, in the optical head device according to the first embodiment, first, a longitudinal section made of a glass material is provided with bearings 2 and 2 for moving the disk 1 in the radial direction at the bottom. A base 17 having an L-shaped surface serves as a base. One end of two upper and lower bimorph type piezoelectric elements 6 arranged in parallel with the horizontal wall 19 is attached to the upper end of the vertical wall 18 of the base 17. Lens holding holes (not shown) are provided at the other ends of the piezoelectric elements 6 and 6, and the upper end and the lower end of the lens barrel 8 to which the objective lens 1 is attached are respectively provided in the holding holes. It is inserted and held. On the horizontal wall 19 of the base 17, a reflecting mirror 9 having a triangular shape in a side view is fixed vertically below the objective lens 7.

In the optical disk device equipped with the optical head device of the first embodiment described above, the laser light emitted from the fixed optical system 20 passes through the vertical wall 18 of the base 17 and is reflected by the reflection mirror 9. It is guided to the objective lens 7. The laser light guided to the objective lens 7 is condensed by the objective lens 7, and the light spot thereof is applied to the recording surface of the disc 1. The seek movement of the optical head is performed by a driving device (not shown) such as a linear motor.

In the first embodiment, by adopting such a structure, the through hole for transmitting the laser beam used in the conventional technique is unnecessary, and the rigidity is increased accordingly. Also,
By using glass as the material forming the base 17, the Young's modulus is high and the density is low as compared with the case of the aluminum material which has been conventionally used, so that the rigidity and the weight are reduced. In addition, since the rigidity of the base 17 is increased, unnecessary vibration is less likely to occur in the base 17 during seek operation, so that accurate seek movement is possible, and an optical disc device capable of achieving high density information recording is obtained. To be

Next, a second embodiment will be described with reference to FIG. In the first embodiment, the reflecting mirror 9 and the base 17 are separate parts, whereas in the second embodiment,
As shown in FIG. 2, an inclined surface is formed at one end of a horizontal wall 19 which is vertically below the objective lens 7, and the light deflection surface 21 is provided on this inclined surface.

With respect to the optical head device constructed as described above,
The fixed optical system 20 irradiates the laser light toward the horizontal wall 19.
This laser light passes through the inside of the horizontal wall 19 and is reflected by the light deflection surface 21 to be guided to the objective lens 7. The objective lens 7 collects the guided laser light and forms a light spot on the recording surface of the disk 1.

The second embodiment can eliminate the reflection mirror 9 in the first embodiment by adopting the above-mentioned structure, and can be made thinner accordingly. Further, since the number of parts is changed from two to one, the reflection accuracy of light is also improved.

Next, a third embodiment will be described with reference to FIGS. 3 and 4. As shown in FIG. 3, in the third embodiment, the incident surface of the laser light on the base 17 is an inclined surface having a slight angle (θ in the figure) with respect to the direction perpendicular to the incident direction of the laser light. There is. That is, the laser light is configured so as not to enter perpendicularly to the incident surface of the base 17.

According to the third embodiment having such a structure, the light reflected by the laser light incident surface of the base 17 can be returned to the servo system such as tracking and focusing provided in the fixed optical system 20. Since the laser light reflected by the disk 1 entering the servo system is not affected by the laser light reflected by the incident surface of the base 17, noise generated in the servo system can be reduced.

By the way, in the third embodiment, the surface of the base 17 on which the laser light is incident is an inclined surface, but the invention is not limited to this, and the laser reflected by the light deflection surface 21 as shown in FIG. Base that transmits light when it enters the objective lens 7.
The upper surface of 17 may also be an inclined surface to prevent reflected light from returning to the fixed optical system 20.

Next, as a fourth embodiment, an optical head device and an optical disk device using the optical head described in the second embodiment will be described with reference to FIGS.

FIG. 5 shows an optical head device, in which 22 is a coil, 23 is a guide shaft, 24 is an outer motor yoke, and 25 is a magnet. The horizontal wall 19 of the base 17 is formed with two through holes parallel to the L-shaped side surface on both sides when viewed from the front. Guide shafts 23 and 23 coated with Teflon are slidably inserted into the base 17 in the two through holes. The guide shafts 23, 23 also serve as inner motor yokes, and both ends of the C-shaped outer motor yokes 24, 24 are attached to both ends of the guide shafts 23, 23. On the planes of the outer motor yokes 24, 24 facing the L-shaped side surface of the base 17, magnets each having a length substantially equal to the length of the plane are placed on the sides facing the coil 22, as shown in FIG. It is attached so that it becomes the N pole.

FIG. 7 shows an optical disk device equipped with the optical head device according to the fourth embodiment. In FIG. 7, reference numeral 26 is a disk holder, and 27 is a spindle motor.

When a disc cartridge (not shown) having the disc 1 is inserted into the optical disc device, the disc cartridge is held by the disc holder 26, and the center of the disc 1 is engaged with the spindle motor 27. Then, the disk 1 rotates by rotating the spindle motor 27. A device is installed below the surface of the disk 1 in the optical head according to the third embodiment, and by applying an electric current to a coil 22 formed in the base 17, a force acting on the base 17 in the radial direction of the disk 1. Occurs and a seek operation is performed. Further, a fixed optical system 20 including a servo system for controlling tracking and focusing of a light source and an objective lens is installed behind the optical head device.
The laser light emitted from the fixed optical system 20 passes through the base 17, is reflected by the light deflecting surface 21, and a light spot is formed on the disk 1 by the objective lens 7, and data recording / reproduction is performed.

In the fourth embodiment, by adopting the optical head device having the above-mentioned configuration and the optical disk device equipped with the optical head device, an optical head device in which the moving means of the optical head is extremely small and lightweight is obtained. In addition, since the bearing as in the conventional example is not used, the optical disc device can be made thinner.

Although glass is used as the base material in the embodiments of the present invention, plastic may be used as the base material, and by doing so, the weight is further reduced and the cost is significantly reduced. Can be achieved. Further, in the third embodiment of the present invention, the guide shaft is coated with Teflon to improve the friction, wear characteristics and durability.
In addition, a low friction coefficient material such as fluorine or molybdenum may be coated as a coating material.

[0030]

The present invention has the following effects by adopting the above-mentioned configuration.

First, by using a light transmissive material for the base that is the base for constructing the optical head, it is not necessary to provide a through hole for passing light as in the conventional case, so the strength of the base is improved. , The rigidity is improved. Further, in the optical head device in which the moving means is provided in the optical head, unnecessary vibration is less likely to occur in the base during the seek operation, so that accurate positioning servo can be performed. Further, in the optical disk device provided with this optical head device, the optical head device performs accurate servo, so that the density of information recording can be increased.

Further, since the base has a light deflection surface, a small and thin optical head can be obtained, and since a reflection mirror is not provided as a component as in the conventional case, but a single component, The accuracy of the reflection angle of is also improved.

Further, by using a glass material for the base, it is possible to obtain an optical head with higher rigidity and lighter weight than when an aluminum material is used. Further, by using plastic as the material of the base, further weight reduction and cost reduction can be achieved.

Furthermore, since the base also serves as the winding bobbin, the weight and size of the optical head device can be reduced.

Further, by coating the guide shaft with a material having a low coefficient of friction, even a base made of a light-transmissive material having a relatively low coefficient of friction can be smoothly moved along the guide shaft. The durability of is greatly improved.

Furthermore, by making the surface of the base through which the laser light passes an inclined surface and avoiding the laser light from entering perpendicularly to the base surface, the reflected light reflected by the base surface can be used for tracking and focusing. Since it does not enter the servo system, it is possible to prevent the generation of noise due to receiving inaccurate light.

[Brief description of drawings]

FIG. 1 is a side sectional view showing an optical head device according to a first embodiment of the invention.

FIG. 2 is a side sectional view showing an optical head device according to a second embodiment of the invention.

FIG. 3 is a side view showing a base of an optical head device according to a third embodiment of the invention.

FIG. 4 is a side view showing a modified example of FIG.

FIG. 5 is a perspective view showing an optical head device according to a fourth embodiment of the invention.

6 is a cross-sectional view taken along the line AA of FIG.

7 is a plan view showing an optical disc device including the optical head device of FIG.

FIG. 8 is a side sectional view showing an optical head device according to a conventional example.

FIG. 9 is a perspective view showing an optical head device according to a conventional example.

[Explanation of symbols]

1 ... disc, 3,17 ... base, 4,18 ... vertical wall,
5, 19 ... Horizontal wall, 7 ... Objective lens, 9 ... Reflection mirror, 20 ... Fixed optical system, 21 ... Light deflection surface, 22 ... Coil, 23 ... Guide shaft, 24 ... Outer motor yoke, 25 ...
magnet.

Claims (8)

[Claims] 1. An optical head having an objective lens on a base and a deflecting means for guiding laser light to the objective lens, and means for moving the optical head in a radial direction of a disk-shaped information recording medium. 2. The optical head device according to claim 1, wherein the base is formed of a light-transmissive material, and the laser light is applied to the deflecting means through a part of the base. 2. The optical head device according to claim 1, wherein a part of the base serves as a deflection unit. 3. The optical head device according to claim 1, wherein the light-transmissive material forming the base is glass. 4. The optical head device according to claim 1, wherein the light transmissive material forming the base is plastic. 5. The optical head moving means comprises a guide hole formed in the base, a coil wound around the base, and a guide shaft inserted into the guide hole and movably supported in the radial direction of the information recording medium. The optical head device according to claim 1, wherein 6. The optical head device according to claim 5, wherein the guide shaft is coated with a material having a low friction coefficient. 7. The optical head device according to claim 1, wherein at least one of the surfaces of the base through which the laser light is transmitted has an angle with respect to the incident or emission direction of the laser light. 8. A fixed optical system comprising: the optical head device according to claim 1; and a light source for generating a laser beam, and a fixed optical system for irradiating the deflecting means of the optical head device with the laser beam; An optical disk device comprising an information recording medium.