JPH03198231A - Optical information recording and reproducing device and optical head used in this device - Google Patents

Abstract

PURPOSE:To provide excellent environmental resistance characteristics by using aluminum, ceramics, etc., having a smaller coefft. of thermal expansion for a member to adhere and fix optical parts and using a PPS resin, etc., for a member to constitute a linear motor coil, etc. CONSTITUTION:The optical parts are all adhered and fixed to the 1st constitu tional member 105. Materials, such as aluminum and ceramics, having the low coefft. of thermal expansion are used for the material of the member 105. The generation of a large difference in elongation and contraction between the optical parts and the member 105 is obviated in this way and the peeling of adhesion, etc., are prevented. The member 105 is inserted and molded integrally to the 2nd constitutional member 106 in which the linear motor coil 117 and rails 118, 119 as means for moving a light beam in the radial direction of the disk to the disk 103 surface constitute the sliding guide part. The member 106 is the member separate from the member 105 and is formed by using the PPS polyphenylene sulfide resin. The defects, such as deviation between the optical parts arising from the heating up of the optical head and the peeling of the adhesion, are eliminated in this way.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an optical information recording medium in which information is recorded, reproduced, or erased by irradiating a semiconductor laser onto the surface of a disk-shaped recording medium (hereinafter simply referred to as a disk). The present invention relates to a recording/reproducing device, and particularly to an optical head used in such a device. Note that the optical information recording and reproducing apparatus herein includes all devices that perform only recording, devices that perform only reproduction, and devices that perform both.

[Conventional technology]

2. Description of the Related Art Recently, optical information recording and reproducing apparatuses have been developed that randomly record, reproduce, or erase information at high density using a light beam such as a laser beam, that is, using an optical head.

Various types of optical heads are known for use in such devices, and a conventional example of an optical head for magneto-optical recording will be described below with reference to the drawings.

FIG. 5 shows an example of an integrated optical head used for magneto-optical recording. Information tracks T are formed on a disk D rotated by a drive device (not shown), and an objective lens 4 is arranged below the disk D. ing. This objective lens 4
is movable in the focusing direction in the X direction of the drawing and in the tracking direction in the Y direction of the drawing.

The light beam emitted from the semiconductor laser light source 1 passes through the collimator lens 2 → beam shaping prism 11 → polarizing beam splitter 3 → mirror 12 → objective lens 4 and irradiates the surface of the disk D, and the light beam reflected there passes through the objective lens 4. The light beam passes through the lens 4 → mirror 12 → condensing lens 5 and is split by the polarizing beam splitter 6. One of the light beams passes through the toric lens 10 and enters the servo sensor 8, and the other light beam becomes a polarized beam splitter. 2 more after entering
The light is divided into two parts and enters the RF sensors 9a and 9b, respectively. Information recorded on the surface of the disk D is read by determining the difference between the signals detected by the two RF sensors 9a and 9b. Note that in such an integrated optical head, the entire head portion is movable during seek or the like.

Furthermore, more recently, a separate type optical head has been devised to shorten the seek time of the optical head.

That is, as shown in FIG. 6, in order to reduce the weight of the movable part of the optical head, only the part that needs to be moved at least is provided as a carriage part 32, which is separated from the fixed head part 31.

The carriage portion 32 is provided with a flip-up mirror 33, an objective lens 4, and an objective lens actuator (not shown) for driving the objective lens 4.

In the above-mentioned integrated optical head and separate optical head, each optical component is bonded and screwed to the base member of the optical head.

The base member in the movable part is fixed to the device or integrated with the linear motor coil so that it can move in the radial direction of the disk in cooperation with the near motors.

Furthermore, since the base member has a complicated shape, it has been integrally molded using PP5 (polyphelene sulfide) for the purpose of reducing processing costs and weight reduction.

[Problem that the invention is trying to solve]

However, because there is a large difference in thermal expansion coefficient between the resin that is the material of the base member of the optical head and the glass that is the material of the optical element,
Due to the rise in temperature of the optical head due to the rise in temperature of the drive device and the rise in environmental temperature, the adhesive surface may peel off or the optical components may become misaligned, or the mold structural member itself may expand, causing the optical components to move relative to each other. There was a drawback that information could not be accurately recorded or reproduced using a light beam due to deviations in optical adjustment.

For example, PPS has a low coefficient of thermal expansion among resins, but the maximum coefficient of thermal expansion is a=3.0-4. OX 10-' (1/℃).On the other hand, for glass α=0.5~1.0xlO-'
(1/℃) and several minutes.

[Means to solve the problem]

In view of the above problems, the present invention provides a conventional method that does not cause peeling of optical components from the base member or change in the relative position of optical components even when each of the integrated optical head and the separate optical head is subjected to thermal effects. The first objective is to provide a lightweight optical head with low processing cost, and furthermore, an optical information recording/reproducing system that can accurately record, reproduce, or erase information even under the influence of heat. A second purpose is to provide an apparatus.

The above purpose is to provide a member (ceramics, aluminum, etc.) with a lower coefficient of thermal expansion than the base member of the optical head made of resin such as PPS integrally with the base member, and to adhere and bond optical components onto the member. This can be achieved by fixing the optical head or by using an optical information recording/reproducing device equipped with an optical head having such a configuration.

[Example J Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a diagram showing an optical information recording/reproducing apparatus of the present invention.

In FIG. 1, 135 is a recording medium such as a magneto-optical disk, 136 is a spindle motor that rotates the recording medium 135 at a predetermined number of rotations during recording, reproduction, and erasing.
37 is a spindle servo circuit that controls the spindle motor 136, 138 is an optical head (described in detail later) having a laser source, etc., and 139 is an optical head that is optically detected by the optical head 138 using a laser beam. The head amplifier 140 that processes the reproduced RF signal,
A focusing servo circuit 141 drives and controls an objective lens actuator (not shown) of the optical head in the focusing direction of the recording medium based on a focusing error signal optically detected by the optical head 13B using a laser beam. , an objective lens actuator (
(not shown) in the tracking direction of the recording medium.

In such a configuration, information is recorded, reproduced, and erased.

Next, the details of the optical head shown in Figure 1 are shown in Figures 2 and 3 (a).
, (b) The cases of an integrated optical head and a separate optical head will be explained using FIG.

First, the case of an integrated optical head will be explained using FIG.

102 is a main body cover; 103 is a disk that is an optical information recording medium; 104 is an objective lens that focuses a light beam such as a laser beam onto the disk; and the objective lens 104 is an objective lens drive device (actuator) not shown. It is supported movably in the orcus direction and the tracking direction with respect to the disk 103.

・〜゛＼ (Deprecation margin) The disk 103 is rotatably supported by a rotation drive means (not shown). Further, as shown in the figure, a laser unit 110 having a semiconductor laser 111 and a collimator lens 109 is attached to the optical head. The beam light emitted from the semiconductor laser passes through the collimator lens 10.
9 to make it into parallel light. Further, the parallel light passes through a beam shaping prism 108 and a polarizing beam splitter 107 provided in the optical head, and is directed to the disk 103 by an objective lens 104 which is supported movably in the focusing direction and the tracking direction by an actuator (not shown). A spot is irradiated on the top.

The beam light reflected by the disk 103 passes through the objective lens 1
04, is reflected in a right angle direction by a polarizing beam splitter 107, passes through a condensing lens 112, and enters a half mirror 113.

The beam light incident on the half mirror is separated into two directions as shown in the figure, one of which is incident on a detector 115a via an analyzer 114a, and the other is incident on a detector 115b via an analyzer 114b. Detectors 115a, 11
Of the signals detected separately in 5b, one is detected as a signal in the focus direction and the other as a signal in the tracking direction.

Then, the detected signal is fed back to the above-mentioned actuator, and autofocus and autotracking control of the objective lens is performed based on the signal. Further, the information recorded on the disk 103 is transmitted to the detector 11.
Detection may be made from either 5a or 115b.

All of the above optical components are bonded to the first structural member 105 (made of a material with a low coefficient of thermal expansion such as near-aluminum or ceramic).
Fixed. The first structural member 105 also includes a linear motor coil 117 and rails 118 and 119, which are means for moving the light beam to the surface of the disk 103 in the A-+B force direction (radial direction of the disk) shown in FIG. It is insert-molded integrally with the second structural member (PPS polyphenylene sulfide resin) 106 that constitutes a sliding guide portion with the second structural member (pps polyphenylene sulfide resin).

However, the optical component may be bonded and fixed to the first structural member 105 after being integrally molded, or may be fixed before molding. Also, after insert molding, the first structural member 105
The optical member may be attached after secondary processing is performed on a part of the optical member to improve accuracy.

Note that the first structural member is provided by insert molding in a range including the position where the optical component is bonded or the vicinity thereof, relative to the second structural member.

As the material of the first structural member 105, for example, steel (α=
1 to 1,2x 10-'(1/'C)) ceramics (α=0.1 to 1.0XIO (1/'C)), etc. can be considered. As mentioned above, the coefficient of thermal expansion of glass is α
= 0.5 to 1.0xlO-' [1/°C), so if the above materials are used, almost the same coefficient of thermal expansion can be achieved. Therefore, there is no large difference in expansion and contraction between the optical component and the first structural member, and peeling of the adhesive can be prevented. Aluminum (α
=2.36X10-' [1/℃)), magnesium (
The performance can be improved by α=2.71x 10-' [1/°C).

In the case of using steel, the number of parts can be reduced by making the yoke of the objective lens actuator and the first structural member 105 an integral part.

Next, as another embodiment, a case of a separate optical head will be described.

Figure 4 shows the carriage (movable head) of a separate optical head.
FIG. Note that a fixed head section equipped with a semiconductor laser and a detector is not shown.

Reference numeral 120 denotes a carriage, and the carriage 120 is roughly composed of a first structural member 121 and a second structural member 122. A flip-up mirror 123 and an objective lens actuator 124 are fixed to the first structural member 121 to reflect upward a laser beam L from a fixed head section (not shown). The flip-up mirror is adhesively fixed to the first structural member 121. Objective lens actuator 124
is York 125. Magnet 126. A fixed part consisting of a sliding shaft 127, a pobbin 128. Objective lens 129. It is divided into a movable part consisting of a bearing 130. Pobbin 128 has a focus coil 131 and a tracking coil 13.
2 are provided, and the objective lens 129 can be moved in the focusing direction and the tracking direction, respectively, by passing a current through them based on the reflected light from the disk. Since the bearing 130 is fitted to the sliding shaft 127, the pobbin 128 can also move along the sliding shaft 127.
It is rotatable around a sliding shaft 127.

The second structural member 122 is made of resin (for example, P, P.

Bearings 13 that engage guide rails (not shown) on both sides at S)
3,134. Although not shown, a linear motor pobbin for driving the entire carriage 120 is also provided integrally with the second structural member 123.

The first structural member is insert molded during molding of the second structural member. At this time, the flip-up mirror 123 and the objective lens actuator may be fixed before molding or after molding. In addition, after insert molding, a part of the first structural member 121 is subjected to secondary processing to improve accuracy, and then the flip-up mirror 12 is
3. An objective lens actuator 124 may be attached.

As the material of the first structural member 121, for example, steel (α=
Possible examples include 1 to 1.2 x 10-1 l (1/'C) ceramics (α = 0.1 to 1.0 x lO (1/'C)). As mentioned above, the coefficient of thermal expansion of glass is 0.5 to 1.0XIO-' (1/°C), so if the above materials are used, the coefficient of thermal expansion can be almost the same. Aluminum (α=2, 36 x 10
-' [1/℃] ), magnesium (α=2.71
It is possible to improve the performance even with x 10-' (1/°C) etc.

When steel is used, the number of parts can be reduced by making the actuator yoke and the first structural member 121 an integral part.

〔Effect of the invention〕

As described above, in the optical head, the members for adhering and fixing the optical components and the members constituting the linear motor coil, bearing, etc. are separate members, and the former is made of aluminum, ceramics, etc. with a smaller coefficient of thermal expansion. , the same P as before for the latter
By using PS resin, etc., defects such as misalignment between optical parts and peeling of adhesives due to the temperature rise of the optical head are eliminated, and the optical head has excellent environmental resistance characteristics, and is also lightweight and easy to process as before. made possible to provide. Furthermore, by recording, reproducing, and erasing information using such an optical head, it has become possible to provide an optical information recording/reproducing device with excellent environmental resistance.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an optical information recording/reproducing device of the present invention, FIG. 2 is a sectional view showing an embodiment of an optical head of the present invention, and FIGS. 3(a) and (b) are second illustrations. 4 is a diagram showing another embodiment of the optical head of the present invention, FIG. 5 is a diagram showing a conventional integrated optical head, and FIG. 6 is a diagram showing a conventional separated type optical head. A diagram showing an optical head. 104...Objective lens 105.121...First structural member 106.122...Second structural member 111...Laser source 20 (C-C or 10 Juku 3 TLSB Chictor (III L-17) −

Claims (8)

[Claims] (1) In an optical head that records and reproduces information by irradiating a light beam onto an information recording medium, a light source and a light beam emitted from the light source are guided to the surface of the medium through light shaping, polarization, and focusing. a first structural member that supports an optical component for use with the optical head, a sensor unit that detects a light beam reflected from a medium surface, a moving means that moves the first structural member and the optical head, and a guide mechanism that guides the movement. It has a supporting second structural member, and the material of the first structural member and the material of the optical component have substantially the same coefficient of thermal expansion, and the coefficient of thermal expansion of the second structural member is higher than that of the material. and a light head. (2) In the optical head of claim 1, The first structural member is ceramic or metal. (3) In an optical head that records and reproduces information by irradiating a light beam onto an information recording medium, the optical head is movable and includes an optical component including an objective lens that focuses the light beam onto the medium. a fixed part including a light beam source that generates the light beam and a detector that detects reflected light from the medium, and the movable part includes a first structural member that supports the optical component; , a moving means for moving the first structural member and the movable part, and a second structural member for supporting a guide mechanism that guides the movement, and the material of the first structural member and the material of the optical component are An optical head characterized in that the coefficients of thermal expansion are substantially the same, and the coefficient of thermal expansion of the second structural member is higher. (4) In the optical head of claim 3 The first structural member is ceramic or metal. (5) In an optical information recording and reproducing device that records and reproduces information by irradiating a light beam onto an information recording medium, a light shaping device that guides a light source and a light beam emitted from the light source to the surface of the medium; a first structural member made of a material having substantially the same coefficient of thermal expansion as the material of the optical component, supporting the optical component for deflection and focusing, and a sensor unit for detecting the light beam reflected from the medium surface; a second structural member made of a material having a higher coefficient of thermal expansion than the material of the first structural member, supporting a first structural member, a moving means for moving the first structural member, and a guide mechanism for guiding the movement; 1. An optical information recording/reproducing device characterized by having an optical head. (6) In the optical information recording/reproducing apparatus according to claim 5, the first structural member is made of ceramic or metal. (7) An optical information recording and reproducing device that records and reproduces information by irradiating a light beam onto an information recording medium, which includes a plurality of optical components including an objective lens that focuses the light beam on the medium. a supporting first structural member made of a material having substantially the same coefficient of thermal expansion as the material of the optical component; a moving means for moving the first structural member; and a guide mechanism for guiding the movement. a second structural member made of a material having a coefficient of thermal expansion higher than that of the material of the first structural member; a light beam source that generates the light beam; 1. An optical information recording/reproducing device comprising: an optical head comprising a fixed part provided with a detector for detection. (8) In the optical information recording/reproducing device according to claim 7, the first structural member is made of ceramic or metal.