JP2003335870A - Optical component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical component having a small dimensional change caused by embironmental changes. <P>SOLUTION: This optical component has a coefficient of linear expansion of 2.2×10<SP>-5</SP>/°C or below at a temperature from -20 to 80°C in three-dimensional directions (X-, Y- and Z-axis directions). This optical component is composed of a composition comprising a thermoplastic resin of ≥20 and <50 vol.%, an inorganic filler of >50 and ≤80 vol.% and a fibrous filler of 0-25 vol.%. It is also possible to constitute it with a stainless steel alloy or a meta composition for die casting. This optical component is favorably used as an optical pickup base 6 for an optical pickup device 10. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an optical component,
In particular, the present invention relates to an optical component whose dimensional change due to environmental changes is small.

[0002]

2. Description of the Related Art Conventionally, an optical pickup device used for irradiating a light beam when recording or reproducing information on or from a recording surface of an optical disk such as a compact disk (CD) or a digital versatile disk (DVD), and a high-speed color laser -The optical system housings of printers and high-speed color copying machines have been manufactured by die-casting metals such as aluminum and zinc. Further, in order to reduce the weight of the device, synthetic resin products, for example, optical parts made of polyarylene sulfide have been proposed.

[0003]

However, in recent years, the recording capacity of optical disks has increased, and writable compact disk recordable (CD-R), compact disk rewritable (CD-RW), digital versatile disk random access. Memory (DVD-RA
It has become necessary to increase the recording density and at the same time increase the output of the irradiation laser by increasing the recording and reading speeds of M) and the like. For this reason, the optical pickup device is set at a higher temperature, for example, 50 ° C.
As described above, it is often used particularly at a temperature of 70 ° C. or higher, and it is required that the dimensional stability of the optical component at a high temperature, especially the optical axis deviation of the optical system with respect to the temperature change is small. Further, with respect to the hard disk drive device as well, it is required that the relative positions of the disk unit and the reading unit (arm) be more constant in order to cope with higher density and higher speed. The present invention has been made in view of the above problems, and an object thereof is to provide an optical component whose dimensional change due to environmental changes is small.

[0004]

Conventionally, research and development have been carried out from various viewpoints such as mechanical strength, elastic modulus, toughness, weight reduction or insulating property as a member used in an optical pickup device and having little dimensional change. , The present inventor
It was found that if the linear expansion coefficient in the three-dimensional direction (X-axis, Y-axis, and Z-axis direction) in the range of 80 to 80 ° C. is 2.2 × 10 ⁻⁵ / ° C. or less, the dimensional stability can be significantly improved. The present invention has been completed.

According to the present invention, the optical coefficient of linear expansion at −20 ° C. to 80 ° C. in the three-dimensional direction (X-axis, Y-axis and Z-axis direction) is 2.2 × 10 ⁻⁵ / ° C. or less. Parts are provided.

According to another aspect of the present invention, there is provided a resin composition for optical parts, which comprises the following (A), (B) and (C). (A) Thermoplastic resin or thermosetting resin: The compounding amount in the whole composition is 20% by volume or more and less than 50% by volume. (B) The inorganic filler: The compounding amount in the whole composition is
50% by volume or more and 80% by volume or less (C) Fibrous filler: the compounding amount of the entire composition is 0 to 25% by volume.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below. The optical component of the present invention has a linear expansion coefficient in a three-dimensional direction (X-axis, Y-axis, and Z-axis direction) of −20 ° C. to 80 ° C. of 2.2 × 10 ⁻⁵ / ° C. or less, preferably 2. 1 x
10 ⁻⁵ / ° C. or less, particularly preferably 2.0 × 10 ⁻⁵
/ ° C or lower. If the coefficient of linear expansion in any one of the three-dimensional directions exceeds 2.2 × 10 ⁻⁵ / ° C., excellent dimensional stability will not be exhibited, causing optical axis misalignment. Where X
The axis, Y-axis, and Z-axis directions mean three directions that intersect each other at right angles, and specifically mean the longitudinal direction, the lateral direction, and the depth direction of the measurement test piece. As a material that meets this requirement,
For example, iron, SUS303, SUS304, SUS30
4L, SUS316, SUS403, stainless alloy such as SUS430, aluminum composition, metal such as zinc composition or magnesium composition, alloy or these compositions, metal die-casting composition, thermosetting resin composition or heat A plastic resin composition etc. are mentioned. Among the above materials, from the productivity of optical parts, the composition for metal die casting, a thermosetting resin composition or a thermoplastic resin composition is preferable, and in particular, a thermoplastic resin composition from the viewpoint of weight saving. preferable. Hereinafter, specific constituent components of these compositions will be described.

In the present invention, the composition preferably used is component (A) which is at least one substance selected from thermoplastic resins, thermosetting resins and metals for die casting, and an inorganic filler. (B) component is included.

From the viewpoint of dimensional stability at high temperatures, the thermoplastic resin is preferably a thermoplastic resin having a deflection temperature under load of 100 ° C. or higher, particularly preferably 110 ° C. or higher. As such a thermoplastic resin, for example, polyarylene sulfide, polycarbonate, syndiotactic polystyrene, modified polyphenylene ether,
Examples thereof include polybutylene terephthalate, liquid crystal resin, polyarylate, polysulfone, polyetherimide, polyether sulfone, polyethylene terephthalate, and potiamide. Preferred are polyarylene sulfide, polycarbonate, syndiotactic polystyrene, modified polyphenylene ether, polybutylene terephthalate and liquid crystal resin, and particularly preferred are polyarylene sulfide and polycarbonate. still,
The deflection temperature under load is 0.
It means a value at 46 MPa.

As the thermosetting resin, for example, phenol, epoxy, urethane, unsaturated polyester and the like can be used. Phenol, epoxy and unsaturated polyester are preferable.

As the metal for die casting, for example, aluminum alloy, zinc alloy, magnesium alloy, copper alloy, lead alloy, tin alloy, iron alloy and the like can be used. Aluminum alloy, zinc alloy or magnesium alloy is preferable, and zinc alloy is particularly preferable. Specific examples of the aluminum alloy include Al-Si system and Al-Si.
-Mg system, Al-Mg system, Al-Mg-Mn system, Al-
Specific examples of zinc alloys such as Cu-Si system are Zn-A.
Specific examples of magnesium alloys such as 1-Cu type and Zn-Al type include Mg-Al-Zn type.

The linear expansion coefficient of the composition containing the component (A) is
In order to make it 2.2 × 10 ⁻⁵ / ° C. or less, the inorganic filler which is the component (B) is added. The inorganic filler should be isotropic so that the coefficient of linear expansion of the composition does not become anisotropic. Such inorganic fillers include sericite, kaolin, mica, clay, bentonite, talc, silicates such as alumina silicate, alumina, silicon oxide, magnesium oxide, zirconium oxide, titanium oxide, metal compounds such as iron oxide, Calcium carbonate, magnesium carbonate, dolomite and other carbonates, calcium sulfate, barium sulfate and other sulfates, glass beads, ceramic beads, boron nitride, silicon carbide, calcium phosphate, silica,
Graphite, carbon black, metal powder, etc. may be mentioned. Preferred are silica, calcium carbonate, and metal powder, and particularly preferred is calcium carbonate.

The inorganic filler is pretreated with a silane coupling agent or a titanate coupling agent in order to improve the interfacial adhesion with the component (A) and maintain the mechanical strength of the composition. It is preferable.

If desired, components other than the components (A) and (B) may be added to the above composition. In order to maintain the mechanical strength of the optical component, such as tensile strength, bending strength, impact strength, elastic modulus, etc., as the (C) component,
A fibrous filler may be added. Examples of the fibrous filler include glass fiber, carbon fiber, alumina fiber, silicon carbide fiber, ceramic fiber, asbestos fiber, gypsum fiber, metal fiber, potassium titanate whiskers, zinc oxide whiskers, calcium carbonate whiskers, wollastonite, asbestos. Etc. Among these fibrous inorganic fillers, glass fibers, carbon fibers and whisker fillers are particularly preferable. Like the component (B), the fibrous filler may be used after being surface-treated with a silane coupling agent, a titanate coupling agent, or the like.

Further, as additives, antioxidants such as hindered phenol, hydroquinone and phosphite, heat stabilizers, and ultraviolet absorbers such as resorcinol, salicylate, benzotriazole and benzophenone can be added. Further, various additives such as an antistatic agent, a flame retardant, a nucleating agent, a releasing agent and a pigment which are generally used for synthetic resins may be blended in appropriate amounts.

Regarding the composition ratio of each component in the present invention, when a thermoplastic resin or a thermosetting resin is used as the component (A), the ratio of the component (A) to the composition is 20% by volume or more and 50% by volume. %, Preferably 30-50% by volume
Is. If it is less than 20% by volume, the fluidity of the composition is lowered and the processability is deteriorated. If it is 50% by volume or more, the reduction of the linear expansion coefficient becomes insufficient and the optical deviation becomes large. In this case, the proportion of the component (B) in the composition is
It is 50 to 80% by volume, preferably 50 to 70% by volume.

When a metal for die casting is used as the component (A), the proportion of the component (A) in the composition is 20-9.
It is 0% by volume, preferably 30-60% by volume. If it is less than 20% by volume, the fluidity of the composition is lowered and the processability is deteriorated. When it is 90% by volume or more, the reduction of the linear expansion coefficient becomes insufficient and the optical deviation becomes large. Also in this case,
The proportion of the component (B) in the composition is 10 to 80% by volume, preferably 40 to 70% by volume. In addition, when the component (C), which is a fibrous filler, is added, it may cause anisotropy of the coefficient of linear expansion depending on the amount added, and therefore the minimum required amount should be taken into consideration while considering the requirements of the optical components to be used. It is necessary to adjust the amount added. The proportion of the composition (C) in the composition is
For example, 25% by volume or less, preferably 0 to 15% by volume
Is.

In the method for preparing the thermoplastic resin composition, the above components are mixed in advance in a predetermined mixing ratio, the mixture is put into a kneader, and kneaded at the melting temperature of the resin. As a kneader,
There are single-screw extruders, twin-screw extruders, Banbury mixers, various kneaders, and the like. At this time, it is preferable to granulate (pelletize) from the viewpoint of handling property for the subsequent molding process of the optical component. In the method for preparing the thermosetting resin composition, the above components, a curing agent, a reaction accelerator and the like are kneaded in advance. The method for preparing the composition for die-casting is such that the above components are heated and kneaded at a melting point of the matrix metal or higher in advance,
Make into blocks or pellets.

The method for molding the optical component is not particularly limited, and a known method for processing the substance can be used depending on the kind of the substance used. For example, as a method of manufacturing an optical component from a metal or an alloy, a method such as cutting, electric discharge machining, powder metallurgy, metal injection molding (MIM) can be used. For the low melting point metal or the composition for die casting, a method such as a metal die casting method can be used. Further, in the case of a thermosetting resin composition, a method such as transfer molding can be used, and in the case of a thermoplastic resin composition, it can be manufactured by injection molding, extrusion molding, solvent molding, press molding, thermoforming or the like. Of these molding methods, injection molding is preferable because it is excellent in productivity and dimensional accuracy of molded products. Incidentally, the constituent components of the thermoplastic resin composition may be mixed and directly charged into the molding machine, or the one previously melt-kneaded as described above may be charged.

The linear expansion coefficient of the optical component of the present invention in the three-dimensional direction (X-axis, Y-axis and Z-axis direction) at −20 ° C. to 80 ° C. is 2.2 × 10 ⁻⁵ / ° C. or less, preferably. 2.
1 × 10 ⁻⁵ / ° C. or less, particularly preferably 2.0 × 10
^{It is -5} / ° C or less. Therefore, the optical component of the present invention has a small dimensional change due to environmental changes, and has a very small optical axis deviation even when used in a high temperature environment, for example, a high temperature of 110 ° C. As a specific example of the optical component of the present invention,
Optical components using lasers, for example, optical pickups for CD, DVD or Blu-ray, optical housings for laser beam printers, copiers and liquid crystal projectors, arms or carriages for hard disk drives, especially optical pickups for high-speed DVD devices. There are high-speed color laser beam printers, etc., which are all or a part of equipment that requires dimensional stability. In particular, the optical component of the present invention is useful as an optical pickup substrate.

An optical pickup substrate which is an optical component of the present invention will be described with reference to the drawings. FIG. 1 is a side sectional view showing an outline of an optical pickup device equipped with an optical pickup substrate for DVD. In this optical pickup device 10, a semiconductor laser light source 1, a half mirror 2, an objective lens 3 and a light receiving section 5 are held on an optical pickup base 6 mounted in a holding container 9. The laser light output from the semiconductor laser light source 1 is converged on the recording surface 8 of the optical disc 7 by the objective lens 3 via the half mirror 2 and the collimator lens 4, and the recording surface 8
The reflected light from the objective lens 3 and the collimator lens 4
Then, the light is incident on the light receiving unit 5 via the half mirror 2 to obtain an error signal such as a data signal and a focus error signal. It has a mechanism for adjusting the position and the like of the objective lens 3 with respect to the error signal. Further, the optical pickup substrate 6 can irradiate laser light over the entire recording surface 8 of the optical disk 7 while moving in conjunction with the shaft in the holding container 9. The optical pickup substrate 6 is exposed to a temperature environment of about −20 ° C. to about 80 ° C. However, since the linear expansion coefficient is small, the optical axis shift is small, and each member functions accurately.

[0022]

EXAMPLES Examples of the present invention will be described below, but the present invention is not limited to these examples. [Example of Use of Thermoplastic Resin Composition] Example 1 40 volumes of cross-linked polyarylene sulfide (B100: hereinafter referred to as PAS) having a melt viscosity of 100 poise at a resin temperature of 300 ° C. and a shear rate of 1000 sec ⁻¹ . % And calcium carbonate (Shiraishi calcium, Whiten P30) 60% by volume are charged into a twin-screw extruder (Toshiba Machine, TEM35B), and 320
The mixture was melt-kneaded at 0 ° C. to prepare pellets of the composition. The deflection temperature under load of this composition was 220 ° C. The pellets were put into an injection molding machine (manufactured by Japan Steel Works, 50 ton molding machine), and an optical component was manufactured using a mold of an optical pickup substrate for DVD. Molding conditions are resin temperature 320
The mold temperature was 135 ° C.

Example 2 An optical component was produced in the same manner as in Example 1 except that the content of PAS was changed to 30% by volume and the content of calcium carbonate was changed to 70% by volume.

Example 3 The content of PAS was changed to 40% by volume, the content of calcium carbonate was changed to 55% by volume, and 5% by volume of glass fiber (manufactured by Asahi Fiber Glass, trade name: JAFT591) was added. An optical component was produced in the same manner as in Example 1.

Example 4 Polycarbonate having a deflection temperature under load of 150 ° C. instead of PAS (trade name: A190, manufactured by Idemitsu Petrochemical Co., Ltd.)
An optical component was produced in the same manner as in Example 1 except that 0) was used.

Comparative Example 1 PAS was 18% by volume and calcium carbonate was 8%.
An optical component was manufactured in the same manner as in Example 1 except that the content was changed to 2% by volume, but the moldability was poor and a component that could be used was not manufactured.

Comparative Example 2 An optical component was manufactured in the same manner as in Example 1 except that the compounding amounts were changed to PAS 50% by volume and calcium carbonate 50% by volume.

Comparative Example 3 An optical component was manufactured in the same manner as in Example 1 except that the compounding amounts were changed to PAS 65% by volume and calcium carbonate 35% by volume.

[Example of Use of Metal] Example 5 An optical component was produced from a block-shaped material of a stainless alloy (SUS304L) by electric discharge machining and cutting. The parts were manufactured in the same shape as in Example 1. The machining device is an NC electric discharge machine (M25-C manufactured by Mitsubishi Electric Corporation).
6), NC wire cut processing machine (DWC90G) and surface grinder (Okamoto, PSG-52) were used.

[Example of Use of Metal Composition for Die Casting] Example 6 50% by volume of aluminum alloy (ADC12) and 50% by volume of silica were compounded with an extruder having a screw diameter of φ35 (manufactured by Toshiba Machine Co., Ltd.). A metal composition for die casting was produced. This compound was molded by a die cast machine (80TON, manufactured by Toyo Kikai Kinzoku Co., Ltd.). The parts were manufactured in the same shape as in Example 1. The molding conditions were an injection temperature of 680 ° C.

Example 7 An optical component was manufactured in the same manner as in Example 6 except that the composition was changed to 70% by volume of aluminum alloy and 30% by volume of silica.

Example 8 An optical component was manufactured in the same manner as in Example 6 except that the composition was changed to 40% by volume of aluminum alloy and 60% by volume of silica.

Comparative Example 4 An optical component was manufactured in the same manner as in Example 6 except that silica was not mixed and the aluminum alloy was changed to 100% by volume.

Comparative Example 5 An optical component was produced in the same manner as in Example 6 except that the composition was changed to 17% by volume of aluminum alloy and 83% by volume of silica, but the moldability and the physical properties of the composition were poor. It was not possible to manufacture parts that could be used.

[Evaluation of Optical Components] 1. Measurement of Optical Axis Deviation Amount of optical components (DVD
The laser diode (LD) and the half mirror were fixed to the pickup part) with a UV curing adhesive (Kyoritsu Chemical Industry, World Rock 8000 series). This component was fixed to a jig, placed in an oven capable of being controlled and held at a temperature of -40 to 80 ° C or higher, a laser was emitted, and the angle of the reflected light from the half mirror was measured by an autocollimator. At this time, the zero point was adjusted at room temperature of 23 ° C. to determine the origin. Next, the oven was heated to 80 ° C., and after holding for 10 minutes, the amount of laser deviation was measured at an angle (min), and this value was taken as the amount of optical axis deviation. Since the position of the half mirror shifts due to the influence of linear expansion due to temperature, it is presumed that the optical axis shifts. 2. Evaluation by an actual machine The manufactured optical parts were installed in a DVD-ROM drive of 48 times speed, and in the use environment of -20 ° C to 80 ° C,
It was judged by whether or not a reading error occurred. When no reading error occurred, it was evaluated as ○, and when it was found, evaluated as ×.
In addition, the optical axis deviation at 80 ° C. was 0.1 in the measurement by the light output method.
It has been confirmed that when it is 0 or less, it can be used even in the evaluation of actual equipment, and when it is more than that, it cannot be used. 3. Linear expansion coefficient A part of the manufactured optical component was cut into a test piece in a three-dimensional direction (MD direction x, TD direction y, thickness direction z), and measured in a temperature range of -20 ° C to 80 ° C. The shape of the test piece is 5 mm x 5 mm x 2 mm, and the measurement is ASTM
D696 (TMA method). 4. Moldability In the molding process, when a molded product which can be evaluated by the actual machine was obtained, it was evaluated as ◯, and when a molded product which could not be evaluated by the actual machine was obtained, it was evaluated as x. Table 1 shows the evaluation results of the optical components when the component (A) is a thermoplastic resin. Table 2 shows the evaluation results of the optical components when the component (A) is a metal.

[0036]

[Table 1]

[0037]

[Table 2]

[0038]

According to the present invention, it is possible to provide an optical component whose dimensional change due to environmental changes is small.

[Brief description of drawings]

FIG. 1 is a side sectional view of a DVD optical pickup substrate of the present invention.

[Explanation of symbols]

1 Semiconductor laser light source 2 half mirror 3 Objective lens 4 collimator lens 5 Light receiving part 6 Optical pickup board (optical parts) 7 Optical disc 8 Optical disc recording surface 9 holding container 10 Optical pickup device

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Claims (10)

[Claims] 1. Three-dimensional direction (X-axis, Y-axis and Z-axis directions)
Has a linear expansion coefficient of 2.2 × at −20 ° C. to 80 ° C.
An optical component having a temperature of 10 ⁻⁵ / ° C. or less. 2. The optical component according to claim 1, wherein the optical component is made of a stainless alloy, an aluminum composition, a zinc composition or a magnesium composition. 3. The optical component according to claim 1, wherein the optical component is composed of a composition containing the following (A) and (B). (A) Thermoplastic resin or thermosetting resin: The compounding amount in the whole composition is 20% by volume or more and less than 50% by volume. (B) The inorganic filler: The compounding amount in the whole composition is
50% by volume or more and 80% by volume or less (C) Fibrous filler: the compounding amount of the entire composition is 0 to 25% by volume. 4. The optical component according to claim 3, wherein the deflection temperature under load of the thermoplastic resin composition is 100 ° C. or higher. 5. The optical component according to claim 3, wherein the thermoplastic resin is one or more of polyarylene sulfide, polycarbonate, syndiotactic polystyrene, modified polyphenylene ether, polybutylene terephthalate or liquid crystal resin. . 6. The optical component according to claim 1, wherein the optical component is composed of a composition containing the following component (A) and component (B). (A) Metal for die casting: 20 to 90% by volume of the total composition, (B) Inorganic filler: the total amount of the composition,
10-80% by volume 7. The metal for die casting is an aluminum alloy, a zinc alloy or a magnesium alloy.
The optical component described in. 8. The optical component is a compact disc,
The optical component according to any one of claims 1 to 7, which is at least a part of an optical housing of a digital versatile disk or a Blu-ray disc, a laser beam printer, a copying machine or a liquid crystal projector, an arm or a carriage of a hard disk drive. . 9. The optical component according to claim 8, wherein the optical component is an optical pickup substrate. 10. A resin composition for an optical component, which contains the following (A), (B) and (C). (A) Thermoplastic resin or thermosetting resin: The compounding amount in the whole composition is 20% by volume or more and less than 50% by volume. (B) The inorganic filler: The compounding amount in the whole composition is
50% by volume or more and 80% by volume or less (C) Fibrous filler: the compounding amount of the entire composition is 0 to 25% by volume.