JP2605622B2 - Inner / outer circumference access optical head drive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk drive,
In particular, high-speed access to the inner and outer circumferences of the optical head of an optical head of an optical memory device such as a high-speed access compatible, high transfer rate digital image file, a high-definition compatible image memory device, or a high-speed computer compatible graphic workstation (GWS). The present invention relates to an optical system of an optical disk device for enabling the optical disk device, and an inner / outer-peripheral access optical head driving device for detecting a position in an optical disk radial direction and performing a high-speed driving device.

[0002]

2. Description of the Related Art Research on an external storage device having both the high-speed accessibility of a magnetic disk for a computer and the large-capacity memory of an optical disk is progressing rapidly. It is certain that next-generation disk devices will become optical disk devices because of their high transfer rate, high-speed random access, large-capacity memory and medium storability, and medium durability due to non-contact.

[0003] Erasable magneto-optical disks and phase change disks are promising optical disk media. For high-speed random access, a large acceleration is required at the time of movement to enable high-speed movement between the inner and outer circumferences of the disk. In order to increase the acceleration, it is necessary to reduce the weight of the movable body as much as possible and to perform electromagnetic drive mainly using a high-efficiency magnetic circuit.

FIG. 5 and FIG. 6 show, for example, Patent Application Publication 3-1.
A configuration for detecting a disk radial position of a conventional inner / outer circumference access optical head as disclosed in Japanese Patent No. 10416 is shown. A beam emitted from a light emitting diode (LED) passes through a slit encoder and is received by an optical sensor via a slit filter corresponding to the slit encoder. FIG.
Shows a cross-sectional configuration for explaining this function. LED5
Light emitted from 1 passes through a slit encoder 52, passes through a slit filter 53 which is a light receiving portion, and is received by an optical sensor 54. A guide 55 is provided to facilitate mechanical setting of the slit encoder 52 and the encoder.

[0005]

As described above, in order to perform high-speed random access, it is important to accurately detect the position of a movable body that moves on the inner and outer circumferences of a disk. However, with respect to the LED light source as described above, the configuration of the Talbot interferometer using the slit encoder and the slit filter for receiving light can only provide an accuracy of about ± 10 μm. In addition, if the gap between the position of the film-shaped slit encoder and the position of the slit filter in the light-receiving portion is deviated, the accuracy is deteriorated. It is an object of the present invention to accurately and stably detect the position of the inner and outer circumferences of a disk without any mechanical constraints.

Conventionally, such an inner / outer-peripheral access optical head needs to accurately detect the radial position of the optical disk, and if a portion for detecting this position is added to a movable body, it is necessary to obtain high thrust corresponding to high-speed access. In order to accurately detect the position, conventionally, it is necessary to detect the position pulse for each slit by using a transmission or reflection type linear encoder as an increment type. As such detection, there is a detector such as Talbot interference, but it is generally not suitable for weight reduction.

Further, conventionally, such an inner / outer peripheral access optical head has to be provided with a flexible substrate extending from the movable body and a coaxial cable for a high frequency one in combination with the optical performance and the dynamic characteristics of the movable body such as a linear motor. With regard to devices aiming for high transfer rates, considering that it is disadvantageous to provide a magneto-optical detection system that connects a head amplifier etc. directly to an optical sensor in the movable part, because the weight of the movable body is further increased. It is necessary to summarize.

Therefore, an object of the present invention is to provide a magneto-optical inner / outer-peripheral access optical head for high-speed access, in which a part of the optical system is arranged on a movable body, the weight of the movable body is reduced as much as possible, and there is a demand for an optical head. It is an object of the present invention to provide a form suitable for signal processing.

In particular, the weight of the entire movable body is reduced by incorporating a lightweight position sensor into the movable body including the objective lens actuator.

[0010]

According to the present invention, in order to achieve the above-mentioned object, in particular, a structure of a separation type magneto-optical head is provided.
An optical component capable of detecting at least one beam type push-pull tracking error is provided in a portion constituting the movable body.

For this reason, detection is carried out via a non-polarizing beam splitter and at least a two-part optical sensor. The fixed optical system has a focus error signal and a magneto-optical detection system.

A sensor for detecting the radial position of the optical disk uses a collimated beam. The reflected light of the optical disk for detecting the tracking error signal travels straight through the objective lens and is obtained by a two-division sensor.
Deflects the beam to the objective lens and travels 9
It has a prism that deflects 0 degrees and performs slit detection with two beams by a split convex lens described later. By attaching the movable body from the inner periphery to the outer periphery in this way, the optical system of the movable body is integrated, and the weight is reduced as much as possible.

In the inner / outer-peripheral access optical head driving apparatus of the present invention, in a separate type optical head optical drive for high-speed access, grooves are provided above and below a long yoke, and an objective lens is provided in the upper groove in the focus direction. An adjacent magnet of opposite polarity for driving is arranged, a linear encoder with a cassette coat is provided in the lower groove, and a rectangular coil that doubles as a tracking drive is provided for access to the inner and outer circumferences. A plurality of roller parts are provided on four sides,
The shaft abutting on this coil is provided with cutouts at the four corners of the yoke, where four shafts are arranged,
This coil further has a 45
Attachment of a mirror plate and a parallel leaf spring type attachment part for focus drive. A 45 ° mirror part attachment part deflects 90 ° and deflects the beam incident on the objective lens by 90 ° downward. An optical encoder for forming a spot and detecting a radial position of a disk is formed.

[0014]

According to the present invention, the one-beam tracking error detection can be stably taken out from the inner and outer access optical heads by the above-described structure, and a portion for detecting the radial position of the optical disk is provided. A large thrust can be obtained by adopting a configuration in which the thrust is applied.

[0015]

Next, the present invention will be described with reference to the drawings.

FIG. 1 is an exploded perspective view showing an embodiment of the present invention, FIG. 2 is a cross-sectional view in a direction perpendicular to the disk radial direction, and FIG. 3 detects the optical disk radial position of an objective lens actuator and a tracking error signal. It is a perspective view of an optical system.

Referring to FIG. 1, a recess 12 above a center of a magnetic yoke (yoke) 11 having an H-shaped cross section is provided.
A magnet 13 of opposite polarity extending from the inner circumference to the outer circumference of the optical disk is arranged, and a reflective linear encoder 15 is attached to the lower recess 14. Grooves 15, 16, 16, 17 and 18 are attached to the four corners of the outer periphery of the H-shaped yoke, and shafts 25, 26, 27, and 28 are attached.

A movable body 19 including an objective lens actuator to be described later is fitted in the center H-shaped yoke 11. The yokes 29 and 30 constituting a magnetic circuit for driving a coil which performs both the tracking operation and the inner and outer peripheral operations of the optical disk are attached to both sides of the center yoke 11. An optical system described later is mounted on the movable body 19, and a tracking error signal detection and an optical disk radial position detector are mounted. Further, a collimator beam 21 extends from the fixed optical system 20 to this optical system.

Referring to FIG. 2, shafts 25, 26, 27, 28 for movement of the inner and outer circumferences and roller bearing systems 35, 35 ', 36, 36', 37, 37 ', 38,
38 ', a magnetic circuit system for focus driving, an optical system for tracking error signals, and an optical system for detecting the radial position of the optical disk are shown.

This magnetic circuit system is an H-shaped magnetic yoke 11
And long magnetic yokes 29 and 30 form a closed magnetic circuit, and permanent magnets 201 and 202 are attached. A rectangular coil 19 is arranged in the magnetic gaps 203 and 204 so as to move from the inner circumference to the outer circumference of the disk.

The focus magnetic circuit system is long in the direction extending in the disk radial direction, and has a magnet 20 having a magnetic pole different from NS in the disk axis direction (hereinafter referred to as a focus direction).
5,206,207,208 were arranged.

A rectangular coil 2 corresponding to this magnetic circuit
09 and 2010 are attached to the lens holder 40. Since the current directions of the coils in the parallel lines opposed to the focusing direction of the rectangular coils 41 and 42 are opposite to each other, and the magnetic poles are opposite, the focusing direction is opposed. The coils at the parallel lines get the same force according to Fereming's left-hand rule. This realizes focus drive of the objective lens.

Further, the optical system separates the collimated beam emitted from the fixed optical system into an optical path system for guiding the objective lens and a direction extending in the direction toward the lower surface of the disk. As a means for splitting the light, a composite prism 45 including a beam splitter and a mirror is arranged. This optical path system will be described in detail later in the description of the optical encoder.

The tracking drive and the driving of the inner and outer circumferences of the optical disk are performed by a large rectangular coil 19. This large coil frame is a movable body. A substantially V-shaped roller 35-38 'shown is attached to the frame 19, and is in contact with the shafts 25, 26, 27, 28.

Next, the position detection in the radial direction of the optical disk will be described with reference to FIG. FIG. 3 is a perspective view of an optical system for detecting a radial position of an optical disk of an objective lens actuator and a tracking error signal. The above-described collimated beam 21 is guided downward in the figure by the composite prism 45, and a long hole is formed in the concave portion of the H-shaped yoke and penetrates vertically. Reflective encoder 5 in the recess at the bottom of the H-shaped yoke
0 is arranged, and an incremental type position detection is performed using a slit optical system composed of two beams.

For focus driving, rectangular focus coils 41 and 42 are attached to both sides of a substantially box-shaped lens holder 40 and supported by parallel leaf springs 43 and 44.

The collimated beam 21 emitted from the fixed optical system 20 is deflected by 90 ° at the beam splitter portion of the composite prism 45 composed of a beam splitter and a mirror, reaches the objective lens 46, and the reflected light from the optical disk travels straight through the composite prism 45. Then, the light reaches the two-division optical sensor 47 for detecting the tracking error signal.

The collimated beam 21 is applied to the composite prism 45
The beam that goes straight through the beam splitter is deflected downward by 90 ° at the 45 ° mirror portion, goes straight through the split lens 48 and the beam splitter 49, and enters the two beam spots 51, 51 into the cassette-coated reflective linear encoder 50.
Focus as 52.

The reflected light of the two beams of the cassette-type reflective linear encoder 50 for dust protection returns to the beam splitter 49 in the reverse order, is deflected by 90 ° by the beam splitter 49, and shifted by 90 ° by the two-division sensor 53. To obtain a pulse output.

From these two pulses, the inner circumference of the optical disk,
The outer peripheral direction is detected, and position information based on the increment pulse is detected.

The optical system using the split lens for detecting the radial position of the optical disk is configured to move the hole of the H-shaped yoke from the inner circumference to the outer circumference. That is, a part for inserting the optical system is provided in a part of the yoke 11, or an optical system using a split lens is mounted after a moving body based on the coil frame for tracking drive is mounted on a rail mounted on the yoke.

The optical system based on the split lens 48 is configured so that the optical system based on the split lens 48 can be rotationally adjusted so that the degree of modulation of the pulse characteristic having a phase difference of 90 ° can be increased in accordance with the pitch of the linear encoder 50. . This adjustment will be described with reference to FIG. 4 to make it easier to understand. The two spots deflected by the beam splitter 49 are received by the split sensor 53 to obtain A-phase and B-phase encoder outputs.

With the above arrangement, high-speed access is made possible by providing a coil frame 19 serving as a base of a movable body that supports high-speed access and a portion for detecting the disk radial position, which also serves as tracking and positioning.

[0034]

As described above, according to the present invention, when an optical head for accessing the inner and outer peripheries of an optical disk device at high speed is performed in a separated type, the weight of the movable parts is reduced drastically, and the sled drive is used. Because of the configuration
It is possible to obtain a remarkable acceleration characteristic as compared with the conventional one, and at the same time, it is possible to stably extract a tracking error which is important for servo by a one-beam system.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing a configuration of an embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a perspective view showing a configuration of a movable body in the embodiment of FIG.

FIG. 4 is a diagram for explaining detection of a disk radial position in the embodiment of FIG. 1;

FIG. 5 is a partial cross-sectional view showing an encoder part in a conventional example.

FIG. 6 is a partial cross-sectional view showing an encoder part in a conventional example.

[Explanation of symbols]

11 H type magnetic yoke 29, 30 Side yoke 15 Linear encoder 19 Tracking drive coil 20 Fixed optical system 35, 35 ', 36, 36', 37, 37 ', 38, 3
8 'Roller 41 Lens holder 41, 42 Square shaped coil 47 Two-split sensor 49 Beam splitter 53 Two-split sensor

Claims (3)

(57) [Claims] In a separate type optical head optical drive for high-speed access, grooves are provided above and below a long yoke, and adjacent upper and lower magnets for driving an objective lens in a focusing direction are provided in upper grooves. Is provided, a linear encoder with a cassette coat is provided in the lower groove, and a rectangular coil serving also as a tracking drive is provided in the inner and outer access, and a plurality of roller portions are provided on four sides inside the coil bobbin, The shaft contacting the coil is provided with cutouts at the four corners of the yoke, and four shafts are arranged here.
A mirror part and a parallel-plate spring mounting part for focus drive are attached. A 45-degree mirror part is deflected 90 degrees and a beam incident on the objective lens is deflected downward by 90 degrees. An inner / outer-peripheral access optical head driving device, wherein an optical encoder for forming a spot and detecting a radial position of a disk is formed. 2. A groove extending from an inner periphery to an outer periphery is provided in a yoke body having a substantially H-shaped cross section in the optical encoder portion, and a beam directed downward from the collimated beam is obtained through the groove. The beam splits the convex lens into two parts and forms a split lens that is arranged with the center position shifted. This lens allows the beam to pass through the beam splitter, converges on the linear encoder, and divides the reflected light from the reflective encoder into two parts. 2. The inner and outer access optical head drive device according to claim 1, wherein the sensor is configured to receive light. 3. The movement of the rectangular coil for driving the inner and outer circumferences of the disk is made up of a plurality of rollers arranged inside the coil and having a substantially V-shaped cross section, and arranged at four corners of the center yoke. 2. The inner / outer-peripheral access optical head driving device according to claim 1, wherein the driving device is formed by contacting the shaft.