JPS62245537A - Lens holder of optical pickup - Google Patents

Abstract

PURPOSE:To obtain a lens holder for an optical pickup which has excellent lubricity and wear resistance and permits focusing and tracking of good stability and sureness by forming the lens holder of a specific compsn. CONSTITUTION:The lens holder of the optical pickup is formed of the compd. prepd. by compounding either or both of an organopolysiloxane having a unit contg. a functional group or fluoropolymer with a composite material essentially consisting of a synthetic resin. The organopolysiloxane is prepd. by introducing the functional group into a homopolymer such as, for example, dimethyl siloxane, methylphenyl siloxane or trimethylfluoropropyl siloxane or copolymer of >=2 kinds thereof and the functional group includes a glycyl group, amino group, carboxyl group, hydroxyl group, merecapto group, isocyanate group, etc. The compounding ratio of said polymers is respectively preferably 0.5-30.0 or 2.0-20.0pts.wt. per 100pts.wt. composite material in the case of the polymer contg. one or plural kinds of the functional groups.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a lens holder for an optical pickup for performing focus control and tracking control of an optical information recording/reproducing device.

[Conventional technology]

Conventionally, in devices such as video disc players, digital audio players, and optical disc files, a light beam for detecting signal tracks (information bit rows) and information on a disc is focused at an appropriate position on the disc surface. deviation from the optical axis of the objective lens (radial deviation of the optical axis)
If this occurs, accurate reading is not possible, so the focus shift of the objective lens is usually compensated for by focusing servo, and the shift of the signal track is compensated for by tracking servo. There are many specific methods for this, but one example is the lens holder for an optical pickup shown in FIGS. 1 and 2.

1 and 2, a base 1 is provided with a support shaft 2 and a magnetic core 3, and a lens holder 10 is rotatably fitted onto the support shaft 2.

The lens holder 10 has a metal sleeve 12 in the center of the holder body 11, a drive coil 13 on the outer periphery, and a lens mounting hole 14 for mounting an objective lens 15 at an eccentric position of the sleeve 12. are doing. Here, the drive coil 13 is arranged at a position facing the focus coil wound around the axis of the sleeve 12, with a plane of symmetry including the axis of the sleeve 12 wound in the optical axis direction of the objective lens 15. A tracking coil (not shown) is included in the lens holder 10 according to the current flowing through the focusing coil and the tracking coil.
The amount of axial movement and rotation of is controlled. Therefore, in order to improve the responsiveness of such control, it is preferable to reduce the inertia force by reducing the weight of the lens holder 10 as much as possible, and the holder body 11 is usually made of aluminum alloy or synthetic resin. Made of lightweight material. In addition, sleeve 1 in FIGS. 1 and 2
2 may be fixed to the separately molded holder main body 11 by press fitting or adhesive, or may be integrally molded with the holder main body 11, and the holder main body 11 is formed as shown in the figure. It is not limited to a cylindrical shape, but may be of any shape such as a prismatic shape. However, in any case, the dimensional accuracy of the inner diameter of the sleeve 12 in contact with the support shaft 2 (corresponding to the inner diameter of the holder body 11 itself when the sleeve 12 and the holder body 11 are integrally molded from the same material) should be improved. Alternatively, a lubricating film such as a fluororesin-containing polymer is formed on the inner surface of the sleeve 12 and the outer peripheral surface of the support shaft 2 in contact with the inner surface to improve the sliding characteristics between the two, thereby reducing the weight. Together with this, efforts have been made to improve the responsiveness and reliability of the holder 10.

Among these methods, when the inner surface of the sleeve 12 is made of metal such as aluminum or its f'i gold, it easily corrodes and generates rust in a high temperature and humid atmosphere, inhibiting normal sliding. In addition, when the holder main body 11 is made of metal, it is usually machined, so there is a drawback that the molding cost is high. In addition, in the method of forming a lubricating film, the lubricating film is made of a fluorine-containing resin with high lubricity such as tetrafluoroethylene resin, tetrafluoroethylene hexafluoride propylene resin, perfluoroalkoxy resin, polyimide resin, polyamide resin, etc. Since it is dispersed in a binder resin such as imide resin or epoxy resin that has excellent adhesion to the base material, a layer rich in binder resin is added to the base material side (adhesive side) of the coating. On the opposite side (sliding surface side), a layer rich in fluorine-containing resin must be formed by taking advantage of differences in cohesive energy density, etc., which inevitably results in a thicker film, and dimensions such as roundness and cylindricity. Not only is it difficult to obtain precision, but the mounting gap between the sliding surfaces of each lens holder 10 and the support shaft 2 increases, resulting in a disadvantage to control stability. In addition, the inner surface roughness of the sleeve 12 that slides on the support shaft 2 is usually about 0.2 to 0.8S when it is made of aluminum or its alloy, which is far from a mirror surface, and the lubricating coating interposed between it and the support shaft 2 is The rough surface scrapes and the generated abrasion powder fills the gap and often causes malfunction. Even if the sleeve 12 is made of synthetic resin, the elastic modulus (rigidity) of the resin is small.
During focusing or tracking, a high-order resonance occurs at a frequency corresponding to the elastic modulus, and control becomes ineffective. Therefore, a method is used to increase the elastic modulus of a composite material by adding glass fibers, carbon fibers, etc. to synthetic resin. However, in this method, the coating surface is scratched by the tips or edges of the composite fibers, resulting in severe abrasion, resulting in the same malfunction as described above.

Furthermore, the combination of the lens holder 10 made of a synthetic resin base material and the support shaft 2 (usually made of stainless steel) without a lubricating coating is very advantageous in terms of cost, but the sliding characteristics are unfavorable. In recent years, lens bolter 10 made of synthetic resin containing solid lubricant such as fluororesin and stainless steel have been developed. Combinations with support shafts 2 made of metals such as, ceramics such as SiC, etc., are also being considered. However, even with this method, if a solid lubricant with a very low elastic modulus such as fluororesin is mixed, the elastic modulus of the lens holder 10 is low, causing the above-mentioned resonance problem, and at the same time, the driving coil, objective lens 15, etc. This is not preferable because even if the sliding properties are improved, it cannot withstand long-term use. In addition, if the lubricant is poorly dispersed in the synthetic resin that serves as the base material, it will actually accelerate wear, and especially wear particles of fluororesin will adhere to the surface of the support shaft 2 in the form of a film.
Since it becomes difficult to remove, it causes poor sliding, and reliability is still insufficient. Furthermore, attempts have been made to adhere a fluororesin film or form a coating on the inner surface of the sliding part of the lens holder 10 that contacts the support shaft 2, but it has not been possible to adhere the film without impairing the dimensional accuracy of the inner diameter. is impossible, and the organic solvent in which the fluororesin is dissolved has a fairly high viscosity even when diluted, and it is usually
It is extremely difficult to construct a small hole with an inner diameter of ~3 mm, and even if the dimensions are achieved by mechanical finishing after construction, the abrasion powder of the fluororesin will be stretched into a film during long-term sliding, and the support shaft will be damaged. It adhered firmly to the outer surface of 2, resulting in malfunction and long-term stability was not ensured.

[Problem that the invention seeks to solve]

As described above, the optical pickup actuator based on the conventional technology, especially the lens holder 10 that constitutes the actuator, has the following features:
None of them are superior in terms of lubrication properties, wear resistance, and high elastic modulus, and there are problems in that the focusing servo and tracking servo lack reliability and durability, such as instability, uncertainty, or inoperability.

[Means for solving problems]

In order to solve the above problems, the present invention provides a composition in which either or both of an organopolysiloxane and a fluorine-containing polymer having a unit containing a functional group are blended into a composite material based on a synthetic resin. The lens holder of the optical pickup is a mixture of the two, and the details thereof will be described below.

First, the synthetic resin-based composite material of this invention has a very high elastic modulus, good stability against temperature changes, low molding shrinkage and thermal expansion, and low water absorption. It is desirable that the dimensional change is small even when water is absorbed.

Therefore, there are no particular restrictions on the type or blending ratio of the synthetic resin or filler, but in normal cases, a relatively large amount of inorganic fibrous or powder filler can be mixed in, and the holder itself Examples of synthetic resins having heat resistance (for example, around 150'C or more) that can withstand the heat generated when attaching accessories such as the drive coil 13 to the drive coil 11 include polyphenylene sulfide resin, polyetherketone resin, aromatic polyester resin, polyetherimide resin, polyamideimide resin, polyimide resin,
Examples include epoxy resins, but these synthetic resins may be used alone or in combination of two or more.

Next, the organopolysiloxane in this invention is
For example, a functional group is introduced into a homopolymer or a copolymer of two or more siloxanes such as dimethylsiloxane, methylphenylsiloxane, and trimethylfluoropropylsiloxane.

The functional groups include, for example, a glycidyl group, an amino group, a carboxyl group, a hydroxyl group, a mercapto group, an isocyanate group, etc., and specific examples of introducing these groups are as follows. Note that the examples for each functional group are not limited to those exemplified.

C113CH3(CH2)3NHC2H4NH2theal. Here, k in these formulas is an alkylene group, etc., and m is 5 to
10000, n indicates a number from 2 to 10o.

Furthermore, the fluorine-containing polymer in this invention is a polyfluoroalkyl polymer or a fluoropolyether polymer. The polyfluoroalkyl polymer is a polymer having a fluoroalkyl group as shown below.

F3O(CF2)7-1H(CF2)6-1CI F2
O(CF2), -1 The fluoropolyether polymer has -CxF2x-0- [where X is an integer of 1 to 4] as a main structural unit and has an average molecular weight of about 1,000 to 50,000.

These fluorine-containing polymers also have functional groups such as glycidyl groups, amino groups, carboxyl groups, hydroxyl groups, mercapto groups, and isocyanate groups introduced like the organopolysiloxanes mentioned above, and specifically include the following. be able to.

That is, C6F, 3C21(40CNH-(CH2)6NC0.

OCN-(Q(2) 6-N1-1co-C,,F,
□-CONH-(CH2) 6-NC0.

C3F1□C2H4OH, C7oF21CONllC2
H40H1C6F13SCH2CH20CO (CI-1
2) 5NII2, C8F, 7SO2F.

HOOC-CF20+C2F4O+-+CF2OCF2
0 child CF2H1m n CF3 HOOC-CF20 child CF2-CF-0 connection CF2O piece CF3, H3COOC-CF20-(-C2F40 view C
F2O肱-CF2COOC113, HOCH2-CF2
0(-C2F40+-〇CF2O+-CF2-CH20
H1 11n Cr2 etc.

When using either or both of the above-mentioned organopolysiloxanes and fluorine-containing polymers having units containing functional groups of the present invention, it is important to ensure that the functional groups of each polymer react with each other. When combined, the reaction further increases the molecular weight of the polymer, which is useful for improving the hardness of the molded article. For example, a polymer whose functional group is a glycidyl group (it may be an organopolysiloxane, a fluorine-containing polymer, or both).

(the same applies hereinafter) and a polymer containing at least one group selected from the functional groups of amino, carboxyl, hydroxyl, and mercapto; a polymer that is a carboxyl or ester functional group and an amino group; A combination of a polymer containing at least one type of group selected from hydroxyl groups, or a combination of a polymer containing incyanate groups and at least one type of group selected from hydroxyl groups, amino groups, mercapto groups, carboxyl groups, and ester groups. A preferred example is a combination with a polymer containing a group.

When using alone one of these organosiloxanes or fluorine-containing polymers containing a glycidyl group,
It is best to add aminos or acid anhydrides to cause the glycidyl groups to react with each other, or when using one containing an isocyanate group alone, add a diamino such as diaminodiphenylmethane or a diol such as ethylene glycol to react the incyanate groups. In order to cause the same functional groups to react with each other, it is preferable to add a substance that exhibits a catalytic action as appropriate. Alternatively, a method may be used in which a trimerization catalyst such as a tin compound is added to increase the molecular weight.

The above blending amount of organopolysiloxane or fluorine-containing polymer is based on the synthetic resin base material when a polymer containing any one of glycidyl group, incyanate group, or cyanate group is used alone. The amount is 0.5 to 30.0 parts by weight per 100 parts by weight of the composite material. This is because when the amount is small (less than 0.5 parts by weight), the effect of improving the sliding properties is insufficient, whereas when the amount is more than 30.0 parts by weight, the mechanical properties of the base synthetic resin are affected. This is because the amount is usually preferably 2.0 to 20.0 parts by weight. In addition, when attempting to combine polymers containing different types of functional groups to react with each other, each polymer containing different types of functional groups is added to 100 parts by weight of a composite material based on a synthetic resin. 0.5-20.0 J
It is sufficient to mix 1 part of i. This is because if the blending amount is less than 0.5 parts, the mutual reaction will be insufficient, and the polymer produced by the reaction will not be able to be bound inside the composite material, and a large amount of components will ooze out, which is undesirable. On the other hand, if the amount exceeds 20.0 parts by weight, the mechanical properties of the composite material will significantly deteriorate, which is undesirable, and the range of 1.0 to 15.0 parts by weight is usually preferable.

Conventionally well known methods can be used to mix the compositions of this invention.

For example, the synthetic resin as a base material and the polymer having the above-mentioned functional group are dissolved individually or appropriately in a solvent (for example, fluorochlorohydrocarbon, etc.),
After mixing with a mixer such as a Henschel mixer, a ball mill, or a tumbler mixer, the solvent is removed and the mixture is fed to an injection molding machine or melt extruder with good melt-mixing properties, or it is mixed in advance with a heated roller, kneader, or Banbury mixer 1.
Melt mixing may be performed using a melt extruder or the like, or polymers having different functional groups may be individually mixed with a synthetic resin as a base material and granulated into pellets, which are then mixed immediately before molding and molded. It may be a method.

[Effect]

In the optical pickup lens holder of this invention, a three-dimensional network structure with lubricating properties of organopolysiloxane or fluorine-containing polymer is formed in a composite material based on synthetic resin, and the network is finely dispersed. Because of its presence, the coefficient of friction is small, and it also works to prevent lubricating substances from falling off.

〔Example〕

Examples and Comparative Examples are shown below, and the blending ratios of raw materials are expressed in parts by weight, and the lubricity and durability test methods performed on molded products made from the obtained compositions are as follows.

Lubricity test: A focus coil was attached to the lens holder, and an optical actuator test head (manufactured by Takeda Riken Kogyo Co., Ltd.; TQ88091) and a function generator (Iwasaki Tsushin Co., Ltd. iM: Fc-350) were used to apply a voltage of 0 to 5 V. A sawtooth wave output voltage (during load) is applied, and the difference between the input waveform and the output waveform (the closer the two waveforms are, the better the lubricity) is determined. Evaluate in three stages: ○ mark), acceptable (△ mark), and poor (x mark).

Durability test: Attach the focusing coil and tracking coil to the lens holder, assemble the drive system, and test the accuracy by ±1.2 mm in the focusing direction and ±0.15 mm in the racking direction.
It was operated continuously based on a vibration frequency of about 20 to 27]-1z with a stroke of mm, and the durability was determined as the period of operation 11j until malfunction occurred. Note that this condition is set as an acceleration mode for actual use.

Further, the main raw materials used in the Examples and Comparative Examples are as follows, and in the following description, these raw materials will be expressed and simplified by numbers or symbols attached to each.

A. Organopolysiloxane [abbreviated as OPS] ■Glycidyl group-containing product (Shin-Etsu Chemical Co., Ltd.: Epoxy-modified silicone oil KF102), ■Amino group-containing product (Niamino-modified silicone oil KF861, manufactured by Shin-Etsu Chemical Co., Ltd.), ■Carboxyl group-containing product ( Made by the same company: carboxyl-modified silicone oil
2-160C), ■Mercapto group-containing product (manufactured by the same company: mercapto-modified silicone oil X-22-980), B,
Fluoropolyether polymer (average molecular weight approximately 2000)
[Abbreviated as l'PFPE] ■ Carboxyl group-containing product l-100C-C, F204C2F40 ) (-CF2
0→-CF2-COOHlm n ■Hydroxyl group-containing product 1-10CH2-CF20+C2F4O view CF2O piece C
F2-CH20H.

■ Incyanate group-containing product C1 catalyst ■ Tertiary amino (N,N-dimethylbenzylamino), [
Phase] Dibutyltin laurate, D, synthetic resin for base material ■Polyphenylene sulfide! Fat (manufactured by Phillips Petroleum Co., Ltd.; Rydon P-4 powder) [
abbreviated as pps], 0 polyetheretherketone resin (UK I.C.
Made by I Corporation: PEEK-150PCPEEK], [Phase] Polyetherimide resin (made by General Electric Co., USA: Ultem 1000) Aromatic polyester resin (made by Dartco Co., USA: XYD)
AR-3RT3QO) Abbreviated as CXYDAR] [Phase] Polyamide-imide resin (Nidoron 4000 manufactured by Amoco, USA)
T) [Abbreviated as PAI] [Phase] Polyimide resin (manufactured by Nippon Polyimide Co., Ltd.: Kelimide 1050) [abbreviated as PABM], ■Epoxy resin (manufactured by Mitsui Petrochemical Epoxy Co., Ltd.: Epomix R-140) C
[Phase] Epoxy resin curing agent (manufactured by Mitsui Petrochemical Epoxy Co., Ltd.: Ebox curing agent Q-643) L: EPC (abbreviation)], [Phase] Carbon fiber (manufactured by Toshisha Co., Ltd. 2) Trading card CF, fiber length 6mm
) Abbreviated as CCF], [Phase] Glass fiber (manufactured by Fiberglass Co., Ltd.: chopped strand fiber length 3 mm) [abbreviated as GF], 〇 Tetrafluoroethylene resin (manufactured by DuPont Mitsui Fluorochemical Co., Ltd.:
Teflon 7J) [abbreviated as PTFE] Examples 1 to 13: The above raw materials were blended as shown in Tables 1 and 2, mixed thoroughly in a Henschel mixer, and then fed to a twin-screw melt extruder. , extruded and granulated under the melt-mixing conditions listed in each table, and supplied to an injection molding machine. Under the molding conditions shown in each table, the lens holder 10, in which the metal sleeve 12 is also made of resin, is integrally formed. Molded. The obtained lens holder 10 was tested for lubricity and durability using a support shaft 2 made of 5US420J2. The test results are shown in Table 3.

Comparative Examples 1 and 2: As shown in Table 2, organosiloxane (OPS)
and fluoropolyether (PFPE) Table 3 is not used at all, or even if a fluorine-containing resin is used, the lens holder is made by performing the same operations as in Example 1 except that it is tetrafluoroethylene resin @ (PTFE). It was molded and tested for its lubricity and durability. The obtained results are shown in Table 3, and the lubricity and durability were significantly inferior compared to Examples 1 to 13.

Example 14: A lens holder was molded and tested in the same manner as in Example 1 except that the blending ratios shown in Table 2 were used and a kneader was used instead of the twin-screw melt extruder. Note that the lens holder was heated in advance at 200° C. for 6 hours before being subjected to the test. The results obtained are summarized in Table 3.

Example 15: Mixing ratio shown in Table 2, 140°C instead of injection molding
A lens holder was obtained in exactly the same manner as in Example 14, except that the molded product was cast in the mold and the obtained molded body was heat-treated in the mold for 4 hours. The test results of the obtained lens holder are also listed in Table 3.

As is clear from Table 3, Examples 14 and 15 also
Similar to Examples 1 to 13, the lubricity and durability were far superior to Comparative Examples 1 and 2.

In any of Examples 1 to 15, no stickiness was observed on the surface of the support shaft after the durability test, which is the case when ordinary oil-impregnated plastics are used.

〔effect〕

As mentioned above, the lens holder for the optical pickup of the present invention retains the mechanical properties of the base synthetic resin and also has excellent lubricity, so it has extremely good stability and reliability. Focusing servo and tracking servo can be performed, and the wear resistance and durability are extremely excellent. Therefore, it can be said that the significance of this invention is extremely large.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view illustrating the structure of an actuator of a conventional pickup, and FIG. 2 is a plan view of FIG. 1. 1. Base, 2. Support shaft, 3. Magnetic core, 10.
... Lens holder, 11... Holder body, 12.
・Sleeve, 13...Drive coil, 14...Lens mounting hole, 15...Objective lens Patent applicant: Western Baer Rulon Industries Co., Ltd. Agent Sickle 1) Sentence - (') (N Procedural amendment Calligraphy (spontaneous) October 7, 1986

Claims (1)

[Scope of Claims] 1. Molded from a composition in which either or both of an organopolysiloxane and a fluorine-containing polymer having a unit containing a functional group are blended into a composite material based on a synthetic resin. An optical pickup lens holder featuring: 2. The organopolysiloxane or fluorine-containing polymer having a unit containing a functional group is an organopolysiloxane or fluorine-containing polymer having a unit containing a glycidyl group, an isocyanate group, or a cyanate group, according to claim 1. Optical pickup lens holder. 3. The organopolysiloxane or fluorine-containing polymer having a unit containing a functional group is selected from an organopolysiloxane or fluorine-containing polymer having a glycidyl group and a functional group such as an amino group, a carboxyl group, a hydroxyl group, or a mercapto group. The lens holder for an optical pickup according to claim 1, which has a composition comprising an organopolysiloxane or a fluorine-containing polymer having a unit containing at least one type of group. 4. The organopolysiloxane or fluorine-containing polymer having a unit containing a functional group is at least one type selected from an organopolysiloxane or fluorine-containing polymer having a unit containing a carboxyl group or an ester group, an amino group, and a hydroxyl group. The lens holder for an optical pickup according to claim 1, which is a composition comprising an organopolysiloxane or a fluorine-containing polymer having a unit containing a group. 5. The organopolysiloxane or fluorine-containing polymer having a unit containing a functional group is combined with the organopolysiloxane or fluorine-containing polymer having a unit containing an isocyanate group and a functional group of a hydroxyl group, an amino group, a mercapto group, a carboxyl group, or an ester group. at least one selected from the group
2. The lens holder for an optical pickup according to claim 1, which is a composition comprising an organopolysiloxane or a fluorine-containing polymer having units containing various types of groups.