JP2583505B2 - Optical pickup lens holder - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a lens holder of an optical pickup for performing focus control and tracking control of an optical information recording / reproducing apparatus.

[Conventional technology]

2. Description of the Related Art Conventionally, in a device such as a video disk player, a digital audio player, and an optical disk file, a signal track (information bit string) on the disk and an objective lens light for condensing a light beam for detecting information at an appropriate position on the disk surface. If there is a deviation from the axis (radial deviation of the optical axis), accurate reading cannot be performed.
Further, the deviation of the signal track is compensated by the tracking servo. Although there are many specific methods, there is a lens holder for an optical pickup as shown in FIGS. 1 and 2, for example.

1 and 2, a base 1 has a support shaft 2
And a magnetic core 3, and a lens holder 10 is rotatably fitted to the support shaft 2. The lens holder 10 has a metal sleeve 12 at the center of the holder body 11,
A driving coil 13 is provided on the outer periphery, and a lens mounting hole 14 is provided for mounting an objective lens 15 at an eccentric position of the sleeve 12.
And Here, the drive coil 13 is disposed at an opposing position with respect to a focus coil wound around the axis of the sleeve 12 and a plane including the axis of the sleeve 12 wound in the optical axis direction of the objective lens 15 as an object plane. And the amount of movement and rotation of the lens holder 10 in the axial direction is controlled in accordance with the current flowing through the focus coil and the tracking coil.
Therefore, in order to improve the responsiveness of such control, it is necessary to reduce the inertia force by reducing the weight of the lens holder 10 as much as possible and to make the lens holder 10 from a non-magnetic material. Is formed of a lightweight material made of an aluminum alloy or a synthetic resin. However, when the lens holder 10 is made of an aluminum alloy, finishing such as cutting is necessary, so there is an inconvenience that the cost is increased, and a synthetic resin is used to reduce the cost or to reduce the weight. Very often.

Even when the lens holder 10 is made of synthetic resin, the sleeve 12 in FIGS. 1 and 2 is made of metal or synthetic resin,
To the holder body by pressing or gluing
And a method of forming the same material as the holder main body 11 and integrally forming the same. Here, the holder main body 11 is not limited to a cylindrical shape as shown in the figure, but may have an arbitrary shape such as a prism.

In any case, the dimensional accuracy of the inner diameter of the sleeve 12 that is in contact with the support shaft 2 (equivalent to the inner diameter of the holder body 11 itself when the sleeve 12 is integrally formed of the same material as the holder body 11) is improved, The clearance between the inner surface of the sleeve 12 and the outer peripheral surface of the support shaft in contact with the inner surface of the sleeve 12 is improved to improve the responsiveness and reliability of the lens holder 10 in combination with the weight reduction. I came.

However, among these methods, when the sleeve 12 is made of a metal material such as aluminum or an alloy thereof, by machining, the dimensional accuracy is excellent, but not only the cost is high but also the temperature and humidity are high. Corrosion easily occurs in the atmosphere, causing rust, which hinders normal sliding.In addition, the sleeve 12 made of synthetic resin is integrally formed of the same material as the holder body 11 mainly in terms of cost. Are often used, but the elastic modulus (rigidity) of the resin is small,
At the time of focusing or tracking, higher-order resonance occurs due to a frequency corresponding to the elastic modulus, and control becomes ineffective. Therefore, synthetic resin is mixed with a large amount of fibrous filler such as glass fiber or carbon fiber to increase the modulus of elasticity as a composite material. As a result, the dimensional accuracy is adversely affected, and the dimensional accuracy such as the roundness of the inner diameter of the lens holder 10 and the shrinkage are deteriorated. As a result, the variation in the mounting clearance on the sliding surface with the support shaft 2 is increased, and the control stability is increased. In addition, abrasion is severe due to scratching the support shaft at the point or edge of the composite fiber or the coating film of the support shaft 2 described later, and the generated abrasion powder is generated on the lens holder 10. The gap between the inner diameter and the support shaft 2 is filled, resulting in a malfunction. Therefore, a large amount of non-fibrous fillers such as mica, kaolin, and graphite with low anisotropy are blended in large amounts to increase the modulus of elasticity, reduce dimensional anisotropy to increase dimensional accuracy, and increase the mating shaft or coating. There is a method to make the film difficult to damage, but in this case, the elastic modulus is still insufficient, warping or sinking is likely to occur even if the anisotropy is lost, the molding shrinkage is large, and it is mixed very multiple This causes a problem that the melt formability is significantly impaired. There is also a method that attempts to solve the problem by combining the two, that is, by blending both the fibrous filler and the powder filler, but depending on the blending ratio of the filler, the respective drawbacks appear and all are satisfactory. What we can do is not yet available.

As described above, the sliding characteristics between the outer peripheral surface of the support shaft 2 and the inner peripheral surface of the lens holder 10 are also important factors. As a method for obtaining the sliding characteristics, (1) a method of blending a fixed lubricant such as a fluororesin with the synthetic resin constituting the lens holder 10 (or the sleeve 12), and (2) a method of mixing the lens holder 10 (or the sleeve 12) On the outer peripheral surface of the support shaft 2 in contact with the inner diameter surface of
For example, a method of providing a lubricating coating such as a fluororesin-containing polymer, (3) a lens holder 10 (or a sleeve)
12) A method of forming a thin film of an organosiloxane or a low molecular weight fluoropolymer on the inner diameter surface (for example, Japanese Patent Application No. 61-48075). However, in the method (1), the elasticity of the lens holder 10 (or the sleeve 12) is low due to the compounding of a solid lubricant having a very low elasticity.
At the same time as causing the resonance problem, the driving coil 13
Alternatively, since the adhesive strength to the objective lens 15 or the like is reduced, even if the sliding characteristics are improved, it is not preferable because it cannot withstand long-term use. Further, the methods (2) and (3) do not reduce the elastic modulus of the lens holder 10 (or the sleeve 12),
In addition, it is excellent in that it can impart sliding characteristics without impairing the adhesiveness of the driving coil 13 or the objective lens 15, but in any case, the dimensional accuracy of the lens holder 10 itself,
In particular, dimensional accuracy such as roundness, cylindricity, and sink of the inner diameter surface of the lens holder 10 is important. In recent years, compact discs for audio have been widely used from stationary to portable or in-vehicle applications.In addition to audio discs, they have begun to be used for information files. External forces greater than before are applied in the horizontal and vertical directions. Therefore, the stability of the control must be obtained by suppressing the variation of the mounting clearance on the sliding surface of the lens holder 10 with the support shaft 2 more than ever. further,
According to the method (2), no matter how much a lubricating film exists on the outer peripheral surface of the support shaft 2, if the sliding characteristics (lubricity, wear resistance, etc.) of the inner surface of the lens holder 10 that slides therewith are poor, Smooth focusing is hindered, causing problems such as the inability to operate unless the amount of power applied to the drive coil 13 is increased, and malfunction due to abrasion powder. Also,
In the method (3), in order for the thin film applied to the inner surface of the lens holder 10 to exhibit a sufficient effect, it is necessary that the inner surface of the lens holder 10 and the thin film are firmly adhered.

Recently, actuators of optical pickups have been used not only for storing general information but also for various information files such as traffic control or medical use. However, even higher reliability is demanded, but as described above, the lens holder 10 made of a synthetic resin has a low rigidity, and a resonance occurs when the lens holder 10 is operated for a short time with high-order vibration when compensating for optical axis deviation. As a result, an error occurs in the focal spot, resulting in a malfunction. This resonance point is determined by the elastic modulus of the material constituting the lens holder 10.The higher the elastic modulus, the higher the resonance point moves to the higher frequency side and the higher the safety. There is a need for a material having a higher modulus of elasticity than has been used.

[Problems to be Solved by the Invention] As described above, the actuator of the optical pickup based on the prior art, in particular, the lens holder 10 constituting the actuator
Are not satisfactory in terms of dimensional accuracy and elastic modulus. Furthermore, focusing on whether the actuator has excellent sliding characteristics (lubricity and wear resistance) when combined with the support shaft 2, focusing servo and There has been a problem that the reliability and durability of the tracking servo due to instability, uncertainty, inoperability and the like are not yet sufficient.

[Means for solving the problem]

In order to solve the above problems, the present invention relates to a polyphenylene sulfide resin (referred to as I), a heat-meltable heat-resistant epoxy resin (referred to as II), and a fiber reinforcing agent (referred to as III). ) And a powdered reinforcing agent (referred to as IV), the proportion of which in the total composition is
25 to 60% by weight of the sum of I and II, 40 to 75% of the sum of II and III
% By weight and I to II is 1 to 9, III by weight ratio.
In this method, a means for forming a lens holder of an optical pickup molded from a composition having a pair IV in the range of 1 to 7 is employed. The details are described below.

First, the polyphenylene sulfide (PPS) resin I in the present invention can be prepared by reacting a halogen-substituted aromatic compound with an alkali sulfide as disclosed in, for example, JP-B-44-27671 and JP-B-45-3368. −27
No. 255, the reaction of condensing an aromatic compound with sulfur chloride by a Lewis acid catalyst, or the presence of an alkali catalyst or a copper salt of thiophenols as disclosed in U.S. Pat. No. 3,274,165. A polymer synthesized by the following condensation reaction, etc., having the general formula It is preferable to use a repeating unit represented by the formula (1) and containing the repeating unit in an amount of 30 mol% or more, because it exhibits properties peculiar to the PPS resin. And as a copolymer component [Where R is an alkyl, nitro, phenyl, alkoxy group, etc.] When the content is less than 10 mol%, the crystallinity of the polymer is not adversely affected.

Immediately after the above-described reaction such as condensation, the PPS resin I is an uncrosslinked product having a color close to white, and has a low molecular weight and low viscosity or is heated to a melting point or lower in air to be oxidized and crosslinked, or In the step of the condensation reaction, the molecular weight is increased to change to a melt viscosity suitable for extrusion molding, injection molding and the like. If the molecular weight is too small, for example, even if it is made to react with an epoxy resin base material to increase the molecular weight, the sliding properties, especially lubricating properties, deteriorate.
Is the temperature at which the melt viscosity is specified by ASTM-D1238, 300 ° C, and the load
The melt flow rate (orifice inner diameter 2.09mm, length 8.00mm) under the condition of 5000g and holding time of 6 minutes is 200g / 10
Less than a minute.

Next, the type of the epoxy (EP) resin II used in the present invention is not particularly limited as long as the main component itself contains an epoxy group, and bisphenol-based, alicyclic-based,
Any type such as a novolak type may be used. Examples of the curing agent include amines, acid anhydrides, polysulfides, and phenol resins. Particularly preferred examples are high-molecular-weight novolak-type phenol resins (for example, T resin manufactured by Mitsui Petrochemical Industries, Ltd .: T resin). Etc.).

It is desirable that the ratio of the PPS resin I to the EP resin II be in the range of 1 to 9 for the addition ratio of the EP resin II main agent and the curing agent. This is because if the ratio exceeds 9, a factor such as warpage, sink, and molding shrinkage cannot be suppressed in dimensional accuracy, and if the ratio is less than 1, the mechanical strength decreases or the added EP resin. This is because, depending on the type, the sliding characteristics may be degraded due to bleed on the surface of the molded product, or the melt fluidity may be adversely affected. In the present invention, since one of the main objects is to improve the dimensional stability of the resin composition, it is extremely important to use a curing agent to form a three-dimensional crosslinked structure between the resins.

As described above, the melt flow rate of the mixture obtained by adding the EP resin II to the PPS resin I was determined by the method specified in ASTM-D1238 using an orifice having an inner diameter of 2.09 mm and a length of 8.00 mm.
Under the conditions of a temperature of 300 ° C and a load of 5000g, the holding time is 6 minutes and 30
It is desirable that the difference between the values for the minutes and the value for the holding time of 6 minutes is 0.7 or less. This is because when the difference between the melt flow rates of the holding time of 6 minutes and 30 minutes is larger than 0.7 at the holding time of 6 minutes, the melt flowability and melt molding stability are slightly lacking. In some cases, the mold cannot be completely filled or continuous molding cannot be performed.

Thus, even if the EP resin II is added and mixed with the PPS resin I,
Since the mechanical properties such as strength and elastic modulus are insufficient, a reinforcing agent is further added.However, the reinforcing agent used in the present invention has a purpose of improving the mechanical strength as well as a phase excess with EP resin II. It is effective in suppressing the molding shrinkage, warpage, sink marks, etc. by the effect and increasing the dimensional accuracy, and specifically limited as long as it can withstand the temperature at the time of melting and molding the PPS resin I. Rather, as the fibrous reinforcing agent III, heat-resistant inorganic materials such as glass fiber, carbon fiber, graphite fiber, wollastonite, potassium titanate whisker, silicon carbide whisker, sapphire whisker, steel wire, copper wire, and stainless steel wire are used. Heat-resistant inorganic composite fiber such as so-called boron fiber or silicon carbide fiber obtained by depositing boron or silicon carbide on one fiber, tungsten core wire or carbon fiber Examples thereof include heat-resistant organic fibers such as aromatic amide fibers, and glass fibers or carbon fibers are preferable in terms of high elastic modulus and high dimensional accuracy. Powdered reinforcing agents include, for example, graphite,
Inorganic powders such as mica, kaolin, talc, glass beads, calcium carbonate, diatomaceous earth, asbestos, carbon, metal powders such as zinc, aluminum, molybdenum and copper, and oxide powders thereof can be exemplified. Since it does not adversely affect dimensional accuracy and sliding characteristics, etc.
Graphite, mica, and kaolin are desirable.

The mixing ratio of the fibrous reinforcing agent III and the powdery reinforcing agent IV is such that the proportion of the total resin composition is in the range of 45 to 75% by weight, and the ratio of III to IV is in the range of 1 to 7. Is preferred. The reason is that if the compounding ratio of the reinforcing agent is less than 45% by weight, the effect of high elastic modulus and high dimensional accuracy cannot be obtained, and if it exceeds 75% by weight, the melt formability is remarkably inferior. . When the ratio of III to IV is less than 1, anisotropy is remarkably exhibited in the molding shrinkage or the thermal expansion coefficient, which has an adverse effect on dimensional accuracy and thermal stability (dimension) during use. If you go over it, it may cause a large sled, sink, etc.
This is because the molding shrinkage also increases, and the dimensional accuracy deteriorates.

The method of mixing the above resins I and II and reinforcing agents III and IV is not particularly limited.
Resin and reinforcing agent separately, or Hensiel mixer,
After dry-mixing using a mixer such as a ball mill or a tumbler mixer, a mixture obtained by melt-mixing (for example, granulation) with a hot roll, a kneader, a Banbury mixer, a melt extruder, or the like may be melt-formed into a predetermined shape. The melting temperature at this time is 280 to 400 ° C. at which the PPS resin melts, preferably 280 to 400 ° C.
Around 350 ° C is desirable. Here, at high temperatures exceeding 400 ° C, EP
It is not preferable because the resin cures too quickly and a uniformly dispersed structure is not formed.

〔Example〕

Raw materials used in Examples and Comparative Examples are collectively shown as follows. Abbreviations are used to simplify the names of the raw materials. These mixing ratios are shown in parts by weight.

I Polyphenylene sulfide (PPS) resin [PPS-1] (Philips Petrolium, USA
International Corporation: Ryton P-4), [PPS-2] (Ryton PR06), [PPS-3] (Ryton V-1), II Heat-resistant epoxy (EP) that can be heated and melt molded Resin Bisphenol A type [EP-1] (Mitsui Petrochemical: E
POMIK R-140), Novolak type [EP-2] (Ciba Geigy: Araldite ECN-1280), EP resin curing agent [Curing agent-1] (Mitsui Petrochemical: High molecular weight novolak type phenolic resin: T range) ), EP resin curing agent [Curing agent-2] (Showa Union Gosei Co., Ltd .: Novolac type phenol resin: BRG-557), III Fibrous reinforcing agent Carbon fiber (Toho Rayon Co., Ltd .: Chopped fiber, fiber diameter 7 μm, fiber 6mm long, epoxy sizing agent), glass fiber (chopped strand, fiber diameter 13μm, fiber length 3mm, aminosilane coupling product, manufactured by Asahi Fiberglass Co., Ltd.), IV powdered reinforcing agent Mica (mica S, Mica Canada) -325), kaolin (Tsuchiya Kaolin: SP-33), graphite (Nippon Graphite Co., Ltd .: ACP), and other support shaft materials [support shaft-1] : R-600, obtained by dispersing fluororesin polyimide resin), the support shaft material [support shaft -2] (stainless steel SUS420J
2, surface roughness 0.15 s), holder body inner diameter coating agent [coating agent] hydroxyl group-containing perfluoropolyether polymer having an average molecular weight of 2000 represented by the following structural formula), that is, HOCH ₂ -CF ₂ OC _{2 F 4 O m CF 2 O n} CF 2 -CH 2 OH example 1-9: after dry-mixing the raw materials at the mixing ratio shown in table 1, a twin-screw extruder (Ikegai Corporation: PCM-30 ), And the mixture is kneaded and extruded at a cylinder temperature of 300 ° C. and a screw rotation speed of 50 rpm for granulation.
Injection molding under the conditions of ℃, injection pressure 900kg / cm ² , mold temperature 135 ° C, cylinder with inner diameter 14mm, outer diameter 23mm, length 13mm, width 1
2.7mm, length 126mm, thickness 3.2mm plate material, dimension accuracy measurement height 9mm, inner diameter 2mm, body diameter 8mm, as shown in Fig. 5
A test piece having a flange diameter of 20 mm and a thickness of 3 mm, a comb flow test for measuring flowability (width 5 mm, thickness 0.4 mm and 0.6 mm), and a lens holder 19 having an inner diameter of 2 mm as shown in FIGS.
Was obtained. The following tests were performed using these test pieces.

(1) Comb flow test: Injection molding under constant conditions using a comb for flow test with a thickness of 0.4 mm and 0.6 mm and a width of 5 mm each, measure the flow length of each thickness, and test 100 pieces. The maximum value and the minimum value of the piece were taken as a measure of melt molding stability.

(2) Flexural modulus: according to ASTM-D790.

(3) Coefficient of thermal expansion: A prism (3 mm square, 8 mm long) whose TMA method (thermomechanical analyzer manufactured by Shimadzu Corporation) is used so that the flow direction of the resin during molding or its perpendicular direction is the longitudinal direction. hand,
The coefficient of thermal expansion in the range of 0 to 90 ° C is determined.

(4) Dimensional accuracy (roundness and sink): Roundness was measured in the axial center using a Taylorund 200 manufactured by Rank Taylor Hobson of the United Kingdom, and sink was measured using a surf coder model SE-3E manufactured by Kosaka Laboratory. Fig. 6 → As shown in the figure, four holes at each diagonal are used to measure the inner diameter shape of the hole with an inner diameter of 2mm in the axial direction. Find the largest one as a sink.

(5) Dynamic friction coefficient: Using a test piece with an inner diameter of 14 mm, an outer diameter of 23 mm, and a length of 13 mm, using a thrust-type friction and wear testing machine, load 1 kg / cm ² , speed 100
Determine the value after sliding for 1 hour with the bearing steel (SUJ2) as the mating material under the condition of m / min.

(6) Endurance test: The support shaft of the optical pickup actuator for measuring the sliding characteristics (the surface of the support shaft made of stainless steel covered with the material for the support shaft or made of stainless steel) and the inner diameter of the lens holder 19 (Apply after diluting the inner diameter coating agent to 3% by weight with Freon,
After heating for one hour and forming a coating of about 1 μm), attach it to the test bench, and install a drive unit (manufactured by our company) and a signal generator (manufactured by Advantest: Signal Generator TR98)
202), a voltage of 0.5 V and a frequency of 20 Hz (sine wave) are applied to the drive coil 20 of the pickup actuator by the applied voltage generator, and the lens holder 19 is mounted. It was driven at an amplitude of ± 1.5 mm and operated continuously on the indoor atmosphere plate. The operating time until the operation failure will be used as a measure of durability, but if the operation is good and the machine can withstand a long operation exceeding 1000 hours, the operation will be terminated in 1000 hours.

(7) Sliding test (vertical method): A lens holder displacement measurement device consisting of an optical actuator test head (Advantest: TQ88091) and an analyzing coder (Yokogawa Hokushinki: 3656) ) Endurance test After 100, 200 and 500 hours, mount the test pickup actuator with the support axis vertical, and consist of a drive unit (manufactured by our company) and a signal generator (FG-350 manufactured by Iwasaki Communication Equipment Co., Ltd.). The imprint voltage generator applies an imprint voltage of 0.1 V and a triangular wave having a frequency of 0.1 Hz to the driving coil 20, and the magnitude of the difference between the imprint voltage waveform and the response waveform of the lens holder 19 (both waveforms are approximated). The better the lubricating property, the better the evaluation.

(8) Sliding test (horizontal method): Except that the support shaft is horizontal, it is exactly the same as the sliding test (vertical method) described in (7) above.

(9) Resonance: The pickup actuator under test is mounted on the same test table as the sliding test (vertical method), and the signal generation from the signal generator is controlled by a servo analyzer (Advantest: Servo Analyzer T592A) to adjust the frequency response function. By measuring, the resonance point is obtained.

Table 2 summarizes the results obtained for (1) comb flow test, (2) flexural modulus, (3) coefficient of thermal expansion, (4) dimensional accuracy, and (5) coefficient of kinetic friction. Was. Furthermore, (6) durability test, (7) sliding test (vertical method),
Table 3 summarizes the results obtained for (8) the sliding test (horizontal method) and (9) the resonance. In Examples 1 to 8, the combination of the support shaft and the inner diameter of the lens holder is the same as the one in which the surface of the stainless steel shaft is coated with the support shaft material and the inner diameter of the lens holder. This is a combination of the lens holder inner diameter with a coating agent applied to the shaft.

Comparative Examples 1 to 9: Except that various raw materials were blended in the proportions shown in Table 4, exactly the same operation as in Example 1 was performed to prepare various test pieces, and various characteristics were examined. The obtained results were obtained. Are shown in Table 5 and Table 3 (both described). As is clear from Tables 2 and 3, Examples 1 to 9 show little variation in the comb flow test and good melt molding stability. In particular, Example 6 using a high molecular weight novolak type phenol resin as an epoxy resin curing agent.
Others are better. The flexural modulus also varies depending on the quality and quantity of the reinforcing agent, but shows a good value.

In addition, the anisotropy of the coefficient of thermal expansion is small, not only the dimensional accuracy is excellent, but also the sliding characteristics are good. From these results, even in the practical characteristics, the durability test secured 1000 hours in all cases, showed good lubrication characteristics even if the support shaft was kept vertical or horizontal, and the resonance point affected by the rigidity of the material It showed a sufficiently high value. On the other hand, as is apparent from Tables 3 and 5, when the amount of the epoxy resin added is out of the limited range of the present invention, that is, in Comparative Example 1, when the amount is substantially not contained, the anisotropic thermal expansion coefficient In Comparative Example 2, that is, when the amount is too large, the dynamic friction coefficient is high, and the sliding characteristics when the support shaft is horizontal are poor. When the ratio of the fibrous material to the powdery material is out of the limited range in Comparative Example 3, that is, when the fibrous material is excessive, the anisotropic thermal expansion coefficient is large, the dimensional accuracy is poor, and the durability is poor. In addition, the dimensional accuracy is poor and the durability is not good even in Comparative Example 4, that is, when there are too many powdery materials. Further, Comparative Example 5 has a low flexural modulus, resulting in a small resonance point and low reliability as a pickup. When the amount is too large as in Comparative Example 6, the melt moldability is extremely poor, and the lens bobbin is formed. I couldn't do that. Comparative Example 7 using a PPS resin having a low melt viscosity such that the melt flow rate exceeds 500 g / 10 minutes, that is, a resin having a low molecular weight, has a high friction coefficient, resulting in durability and sliding characteristics (horizontal method). Both showed bad results. Also
Comparative Example 8 in which no curing agent was used even when EP resin was added
Had poor dimensional accuracy and sliding characteristics, and poor durability. As described above, the combination of the support shaft and the lens holder in Comparative Examples 1 to 8 was completely the same as in Examples 1 to 8, but in Comparative Example 9 in which stainless steel and a holder inner diameter coating agent were combined as in Example 9. Also, it was revealed that the durability was inferior because no EP resin was added.

〔effect〕

As described above, the lens holder of the optical pickup according to the present invention can exhibit high elasticity, high dimensional accuracy, and good sliding characteristics. As a result, the dimensions of the sliding portion between the support shaft and the lens holder can be improved. Extremely high accuracy and excellent lubrication even when the support shaft and lens holder inner diameter are in contact with each other, so even if external forces such as vibration, inertia force, centrifugal force, etc. are applied,
Focusing servo and tracking servo with good safety and certainty can be performed, and the durability becomes very excellent. Therefore, it can be said that the significance of the present invention is extremely large.

[Brief description of the drawings]

FIG. 1 is a plan view illustrating the structure of an actuator of an optical pickup, FIG. 2 is a sectional view of FIG. 1, and FIG.
FIG. 4 is a plan view showing the structure of the actuator of the optical pickup used in the embodiment, FIG. 4 is a cross-sectional view of FIG. 3, and FIG. 5 is a cross-section of a test piece used for measuring dimensional accuracy in the embodiment. FIG. 6 is a plan view of FIG. 1 ... base 2 ... support shaft 3 ... magnetic core 10 ...
Lens holder, 11 Holder body, 12 Sleeve, 13 Coil for driving, 14 Lens mounting hole, 15
... Objective lens, 16 ... Base, 17 ... Support shaft, 18 ... Magnetic core, 19 ... Lens holder, 20 ... Drive coil,
21: Lens mounting hole, 22: Objective lens, 23: Dimensional accuracy test specimen.

Claims (2)

(57) [Claims] 1. A polyphenylene sulfide resin (referred to as I), a heat-resistant epoxy resin capable of heat-melt molding (referred to as II), and a fiber reinforcing agent (referred to as III)
And a powdered reinforcing agent (referred to as IV), the proportion of which in the total composition is 25-60% by weight of the sum of I and II, II
And III are in the range of 40 to 75% by weight, and the ratio of I to II is 1 to 9 and III to IV is 1 to 7 by weight. Lens holder for optical pickups. 2. The melt flow rate of the polyphenylene sulfide resin (I) is determined by the method of ASTM-D1238 using an orifice having an inner diameter of 2.09 mm and a length of 8.00 mm at a temperature of 300.
C., a holding time of 6 minutes, and a load of 5000 g, which is 200 g / 10 minutes or less. The melt flow rate of the molten mixture of the polyphenylene sulfide resin (I) and the epoxy resin (II) is determined by the method described in ASTM-D1238. At 2.09m inside diameter
m, orifice length 8.00mm, temperature 300 ℃, load 50
Claims wherein the difference between the melt flow rate values when the holding time is 6 minutes and 30 minutes under the condition of 00g is 0.7 or less with respect to the value when the holding time is 6 minutes. 2. A lens holder for an optical pickup according to claim 1.