JP2848016B2 - Objective lens actuator and optical head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an objective lens actuator used for an optical storage device or the like. Also large capacity,
The present invention relates to an optical head used for a high-speed optical storage device.

[0002]

2. Description of the Related Art A conventional objective lens actuator is shown in FIG.
The objective lens 602, the electromagnetic coil 603 for focusing operation, the counterweight 60
4 and 605, and the sliding shaft 607 was inserted into a hole 606 in the same direction as the optical axis opened in the bobbin 601.

Alternatively, a conventional optical head uses an objective lens actuator having a structure in which an objective lens is held by two parallel leaf springs and displaced in the optical axis direction by a focusing operation electromagnetic coil, and a seek operation electromagnetic coil is used. It was moving.

[0004]

The demand for higher performance of the optical storage device is not limited, and a mechanism capable of higher-speed seek and higher-speed data transfer is required. Alternatively, a mechanism that can be used with lower power consumption is required. Therefore, there is a problem of reducing the weight of the movable part as much as possible. In the prior art shown in FIG.
04, 605 A large bobbin 601 and a large focusing operation electromagnetic coil 603 increase the weight of the movable part. Also, a large chassis for fixing the sliding shaft 607 was required. In the prior art using two parallel leaf springs,
The length of the chassis holding the objective lens, the parallel leaf spring, the reflecting mirror, and the like is long because the parallel leaf spring is long, and the supporting structure of the parallel leaf spring is also required, so that the weight of the movable part is also increased. Accordingly, an object of the present invention is to reduce the weight of a movable part by making it more compact.

[0005] On the other hand, there is also a demand for increasing the capacity of the optical storage device. For that purpose, there is a problem of reducing the size of the light spot on the optical storage medium surface. Since the conventional technique shown in FIG. 6 uses all the light incident on the objective lens, the size of the light spot on the optical storage medium 608 cannot be smaller than the diffraction limit, and there is a limit in increasing the capacity. there were. Therefore, another object of the present invention is to reduce the light spot without increasing the weight of the movable part.

[0006]

An objective lens actuator according to the present invention is an objective lens actuator which performs a focusing operation by displacing an objective lens in an optical axis direction.
The objective lens has a hole in the same direction as the optical axis, a sliding shaft is inserted into this hole to slide the objective lens, and a sleeve is fixed to the hole of the objective lens. Further, one end of the sliding shaft is fixed to a transparent member, and the transparent member is further characterized by being a reflecting prism for bending an optical path, further between the objective lens and the transparent member It is characterized by having an elastic body.

Further, an optical head according to the present invention has an objective lens having a hole provided in the effective aperture in the same direction as the optical axis, a sliding shaft for sliding the objective lens along the hole, and a sliding shaft. It has a transparent member having one end of a moving shaft fixed thereto, an electromagnetic coil for focusing operation fixed to the objective lens, and an electromagnetic coil for seek operation fixed to the transparent member.

[0008]

【Example】

(Embodiment 1) FIG. 1 shows an embodiment of an objective lens actuator according to the present invention. FIG. 1A is a front view showing a cross section,
FIG. 1B is a side view showing a cross section.

The objective lens 101 has a hole 103 in the same direction as the optical axis 102, into which a sliding shaft 104 is inserted. The sliding shaft 104 is coated with Teflon. The objective lens 101 is fixed to the focusing operation electromagnetic coil 105. A bobbin may be used for fixing, or the flange of the objective lens may be extended using a glass pressing technique or a plastic molding technique, and the focusing coil 105 may be directly adhered thereto. The focusing electromagnetic coil 105 is a single coil wound in a rectangular shape when viewed from above, and is driven in the direction of the optical axis 102 by a magnetic circuit including a magnet 106 and a yoke 107.

One end of the sliding shaft 104 is fixed to a hole formed in a total reflection prism 108 which is a transparent member.

The objective lens 101 and the total reflection prism 1
An elastic body 109 made of rubber is provided between the reference numerals 08 and 08. The rubber is fixed to the flange or bobbin of the objective lens and to the side surface of the total reflection prism.

Embodiment 2 FIG. 2 shows another embodiment of the objective lens actuator of the present invention. 2A is a front view showing a cross section, and FIG. 2B is a side view showing a cross section.

The objective lens 201 has a hole 203 in the same direction as the optical axis 202. A sleeve 204 made of aluminum is fixed to the hole 203. The sliding shaft 205 is inserted therein. Sleeve 204 and sliding shaft 2
The clearance of 05 was 5 μm or less in order to make the inclination of the objective lens 0.1 degrees or less.

One end of the sliding shaft 205 is fixed to a hole formed in a parallel flat glass plate 206 which is a transparent member. 20
Reference numeral 7 denotes a surface reflecting mirror for bending the optical path.

A plastic spring 208 inserted into the sliding shaft 206 is provided between the objective lens 201 and the parallel flat glass plate 206. One end of the spring 208 is on the sleeve 204, and the other end is a parallel flat glass plate 206.
It is fixed to.

(Embodiment 3) FIG. 3 shows an embodiment of an optical head according to the present invention. In this optical head, an optical system composed of a semiconductor laser, a prism, an optical sensor, etc., and a galvanometer mirror for performing a tracking operation are fixed, and only the minimum necessary components, namely, an objective lens, an objective lens actuator, and a total reflection prism are linearly arranged. This is a separation type optical head that seeks by a motor.

FIG. 3A is a front view showing a cross section, and FIG.
(B) is the side view which showed the cross section.

The objective lens actuator shown in FIG. 1 is used. The total reflection prism 301 is a chassis 302
Since the seek operation electromagnetic coil 303 is also fixed to the chassis 302, the seek operation electromagnetic coil 30 is substantially fixed to the total reflection prism 301 which is a transparent member.
3 is fixed. The seek operation electromagnetic coil 303 is wound around the bobbin and slide bearings 304 and 305, and the direction of current flowing through the right and left seek operation electromagnetic coils is the same as the arrow. The bobbin / slide bearing 304 has a circular opening as a reference, and the bobbin / slide bearing 305 has a long hole opening shape having a degree of freedom in the lateral direction. The material of the bobbin and slide bearing was aluminum or polyacetal. 306 and 307 are magnets, and 308 is a yoke. The magnet 306 is mainly for the focusing operation electromagnetic coil, and the magnet 307 is mainly for the seek operation electromagnetic coil. The directions of magnetization of the magnets 306 and 307 are opposite directions on the left and right as indicated by arrows. Two magnets 30
The magnets 6 and 307 may be integrally manufactured as one magnet. Reference numeral 309 denotes a slide shaft and inner yoke, which is a soft magnetic material coated with Teflon.

[0019]

As described above, according to the present invention, since the structure in which the sliding shaft is inserted into the hole of the objective lens can obtain symmetry, no counterweight is required, and the bobbin can be made very small. The bobbin was abolished by devising the brim.

Further, by using the sleeve, the frictional resistance can be reduced and the durability is improved.

Further, by fixing the sliding shaft to the transparent member, only the center of the light beam is used as a shadow as shown in FIG. 4 and necessary peripheral light can be used.

In addition, since the transparent member is a reflection prism, it is not necessary to increase the number of parts for fixing, and the parts can be shared.

Also, by using an elastic body, a damping effect can be provided at the resonance frequency, and a transfer function that can be easily controlled can be obtained. This prevented the electromagnetic coil from interfering with the magnet.

Further, by using the objective lens actuator of the present invention and fixing the electromagnetic coil for seek operation to a transparent member, the weight of the movable part can be greatly reduced, and high speed or low power consumption can be achieved. Because of its smaller size, the resonance frequency was increased, the servo band in the seek direction was widened, and it could be used for a higher-speed optical storage device.

Further, as shown in FIG. 4, the light beam 401 incident on the objective lens has a shadow 402 at the center due to the sliding axis. When having such an intensity distribution on the entrance pupil, a super-resolution phenomenon occurs, and an intensity distribution of a diffraction-limited light spot,
5, a light spot 502 smaller than 501 is obtained.
Thus, the capacity of the optical storage device can be increased.

As described above, the present invention greatly contributes to the development of optical storage.

[Brief description of the drawings]

FIG. 1 shows a first embodiment of an objective lens actuator according to the present invention.
FIG. (A) is an explanatory view showing a cross section viewed from the front, and (b) is an explanatory view showing a cross section viewed from the side.

FIG. 2 shows Embodiment 2 of the objective lens actuator of the present invention.
FIG. (A) is an explanatory view showing a cross section viewed from the front, and (b) is an explanatory view showing a cross section viewed from the side.

FIG. 3 is an explanatory diagram of the optical head of the present invention shown in a third embodiment. (A) is an explanatory view showing a cross section viewed from the front,
(B) is an explanatory view showing a cross section viewed from the side.

FIG. 4 is a diagram showing a light beam incident on an objective lens.

FIG. 5 is a light intensity distribution diagram showing a size of a light spot on an optical storage medium surface.

FIG. 6 is an explanatory diagram showing an example of a conventional objective lens actuator. (A) is an explanatory view showing a cross section viewed from the front, and (b) is an explanatory view showing a cross section viewed from the side.

[Explanation of symbols]

 101 201 602 Objective lens 102 202 Optical axis 103 203 606 Hole 104 205 607 Sliding axis 105 603 Focusing operation electromagnetic coil 106 306 307 Magnet 107 308 Yoke 108 301 Total reflection prism 109 Elastic body 110 608 Optical storage medium 204 Sleeve 206 Parallel plane glass plate 207 Surface reflector 208 Spring 302 Chassis 303 Seek operation electromagnetic coil 304 305 Bobbin and slide bearing 309 Slide shaft and inner yoke 401 Light flux incident on objective lens 402 Shadow due to sliding axis 501 Light at conventional diffraction limit Spot intensity distribution 502 Light spot intensity distribution in the super-resolution according to the present invention 601 Bobbin 604 605 Counterweight

Claims (6)

(57) [Claims] 1. An objective lens actuator for performing a focusing operation by displacing an objective lens in an optical axis direction,
An objective lens actuator, wherein the having the objective lens holes of the optical axis in the same direction, sliding the objective lens by inserting the sliding shaft in the hole. 2. The objective lens actuator according to claim 1, characterized in that to fix the sleeve to the bore of the objective lens. 3. One end of the sliding shaft is fixed to a transparent member.
An objective lens actuator according to 請 Motomeko 1 you wherein a. 4. The objective lens actuator according to claim 3, wherein the transparent member is a reflecting prism for bending the optical path. 5. The objective lens actuator according to claim 3, characterized in that it comprises an elastic member between said transparent member and said objective lens. 6. A objective lens having a set only hole to the optical axis in the same direction in the effective aperture, along the objective lens into the hole
A sliding shaft for sliding Te, a transparent member having one end were fixed for this sliding shaft, pre-SL and the electromagnetic coil fixed focus operation to the objective lens, fixed prior Symbol transparent member electromagnetic for seek operation optical head and having a coil.