JPH066306B2 - Fixture for optical component and manufacturing method thereof - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a fixture for an optical component (hereinafter also simply referred to as “attachment”) and a method for manufacturing the same, and more particularly to an optical pickup for an optical recording medium and an optical pickup. , Measuring instrument using laser,
Further, the present invention relates to an optical signal recording / reproducing apparatus for a microscope or the like, a fixture for optical components such as lenses, mirrors, prisms, etc. in a measuring instrument, and a method for manufacturing the same.

[Conventional technology]

In an optical base (mounting tool) that forms a mounting surface of an optical component by a method such as injection molding or casting using a mold, when the mounting surface of the optical component is a side surface with respect to the mold drawing direction, If you make a protrusion, it will become an undercut and you will not be able to remove it from the mold. For this reason, conventionally, as shown in FIG. 7 (A), a method has been performed in which a flat surface is formed in the die-cutting direction, and an optical component is pressed against the surface and installed. Incidentally, FIG.
In (A), 11 is a mirror, and 20 is a base (mounting tool), which is attached to the side surface 2a of the base 20 by pressing force of a leaf spring (not shown) as shown in FIG. ing. Alternatively, as shown in FIG. 3C, two ribs 2b are formed on the surface of the base 20, and the ribs 2b are formed.
There is a case where the mirror 11 is installed on the surface of the above, but in any case, the side view in the drawing direction of the mold is a flat surface in order to avoid undercut.

[Problems to be Solved by the Invention]

In mounting an optical component, accuracy and stability in the angle of the mounting surface are extremely important problems. In parts that reflect light, such as total reflection mirrors and half mirrors, changes in the mounting angle result in movement of the optical axis, which causes an increase in aberrations in transmissive parts such as lenses.

Now, with reference to FIG. 8, the influence of the angle change in the mirror will be described. As shown in this figure, the light beam a is reflected by the mirror 11 and adjusted so as to come to a predetermined position on the surface of the light receiving element PD. Now, when the mirror 11 causes the angle change of θ ₁ , the angle change θ ₂ of the reflected light beam becomes θ _2.
2 times ₁ Further, the amount of change l _P of the irradiation position of the light beam on the light receiving element PD increases in proportion to the distance 1 between the beam irradiation point P of the mirror 11 and the light receiving element PD, and
1 _P is usually several times as large as the positional deviation l _M of. As a practical problem, for example, in an optical system of an optical pickup for a CD player, it is known that if the position of the light beam on the light receiving element PD is deviated by 10 μm, there will be a problem. 11 (beam splitter) corresponds to an inclination of 1 to 2 μm. Therefore mirror 1
The allowable amount of inclination (mounting angle) of 1 is less than 1 to 2 μm, and it is very important to mount the mirror 11 stably and reliably.

However, in the structure shown in FIG. 7 in which the mirror 11 is mounted on the flat surface portion of the optical base 2, the angle of the mounting surface tends to be unstable. The reason will be described with reference to FIG.

(1) Initial dimensional accuracy; problems due to dust adhesion Various dust particles with a size of 1 to several tens of μm are usually suspended in the work environment. These dust particles 4 are often sandwiched between the optical components such as the mirror 11 and the seat surface 3 of the base 20, as shown in FIG. 9 (A). If dust 4 is caught in the center of the seat surface 3, etc., the mounting angle will change by θ ₃ as shown in the figure, although there will be some difference due to its hardness, which will increase the tilt of the optical axis and aberration. Cause to cause.

(2) Change of angle Change of angle with time When dust is caught in the initial stage of installation as described above,
Even if the mounting weight of the optical parts is about several tens of grams, the dust itself is very small, so several tens to several hundreds kg / mm at that part.
There will be a lot of intensive weighting of ² . As a result, FIG. 9 (B)
As shown in, the dust is crushed and the size changes by χ,
The angle of the mirror 11 changes by θ _χ . Moreover, such deformation is often accelerated by environmental conditions.

Angle change due to external impact Even if the surface of the base 20 is intended to be flat, microscopically, it is easy to form fine irregularities due to scratches on the mold and weaknesses in the molding technology (wrinkles, cavities, welds, etc.). . FIG. 9 (C) shows a state in which a convex portion is formed on the lower portion 3b of the mirror seat surface 3. When the mirror 11 is mounted in such a state, it is difficult for the mirror 11 to easily shift to the state shown in FIG. 3D due to an external impact and to return to the original position. Due to this shift,
This causes an angle change of θ _y .

By the way, in the case of a CD (compact disc) optical pickup, the position of the light receiving element is adjusted to about ± 1 μm, and a slight angle change caused by a change of 1 to 2 μm on the mirror mounting surface 3 causes the light receiving element on the light receiving element. However, there is a problem in that it is difficult to obtain the necessary and sufficient performance because the value is close to ± 10 μm.

[Means for Solving the Problems]

According to the present invention, when the seating surface for mounting the optical component is a side view in the drawing direction of the mold, the heights (undercut dimensions) G of the three protrusions are given by the following formula A × B + A × (C−D ) × (E−F) ≧ G (However, A: wall thickness of fixture (seat surface portion), B: shrinkage ratio during molding and curing, C: linear expansion coefficient of molding material, D: linear expansion of mold material The above problems have been solved by providing a fixture for an optical component formed so as to satisfy a coefficient, E: a melting point of a molding material, F: a temperature at the time of taking out from a mold and a manufacturing method thereof.

[Example] A first example of a fixture for an optical component according to the present invention (hereinafter, also simply referred to as "attachment") will be described with reference to FIG. The main feature of the fixture 1 of the present invention is shown in FIG.
As is clear from (A), the seat surface 3 has two ribs 5a, 5
After forming b, the three protrusions 6a to 6c are formed on both ribs 5.
a) and 5b (in the embodiment, one on the rib 5a and two on the rib 5b) and separated from each other at a distance slightly smaller than the width of the optical component to be attached. Of course, two ribs may be formed on the rib 5a side and one rib 5b may be formed. And on these protrusions 6a-6c, the same figure (B)
As shown in, the optical components such as the mirror 11 are mounted and attached. It is preferable that the protrusions 6a to 6c do not deform due to their weight (pressing force) when the optical component is placed, but if they are formed to have the same size, they will be uniformly deformed, and there is no problem.

Next, the features of the fixture 1 of the present invention will be described. First, as to the problem of the protrusion 3b which is likely to occur when the dust 4 adheres and is molded, as shown in FIG. 2, by forming the protrusions 6a to 6c higher than the size of the dust 4 and the height of the protrusion 3b, It can be avoided easily and sufficiently. Also, the protrusion 6a
With respect to the possibility that dust 4 may adhere to the tops (tops) of 6c and the protrusions 3b may be formed, the probability of occurrence can be reduced by reducing the area of the tops of the protrusions 6a to 6c. For example, the width of the ribs 5a and 5b is 2 mm,
If the length is formed to 5 mm and the protrusions 6a to 6c (the tops thereof) are points having a diameter of 0.1 mmφ, the probability of occurrence is only 1/1273 compared with the occurrence on the ribs 5a and 5b.

As for the displacement of the optical component due to an external impact, as shown in FIG. 2, even if the optical component is displaced in the direction of the arrow Y from the position indicated by the broken line to the position indicated by the solid line, there is no change in the angle. There is no.

As described above, when mounting the optical component, it is best to mount the optical component at three points that are not on the same straight line on the seat surface. However, the metal for integrally molding the mounting tool 1 having such a shape is used. When the side surface of the mold with respect to the pulling direction hits the seating surface (mounting surface of the optical component), these protrusions 6a to 6c are undercuts. It was not used conventionally.

For molded plastic parts that do not require high precision, the elasticity of the material was used to deform it and forcibly pull it out. According to this method, scratches (scratches) are generated on the undercut surface, and therefore, the optical parts cannot be roughly processed in terms of accuracy. In the case of a large plastic part, as shown in FIG. 10, in the die 12, a part 13 constituting the die 12 is slid by a solenoid 14 or the like to pull it out, or an undercut portion is formed by rotating it. There is also a method of pulling it out, but this requires a space that allows the mold to have a double structure, and in many cases it cannot be implemented with small parts such as an optical pickup. Also, 2
Due to the heavy structure, the dimension becomes unstable, and the molds 12 and 1
However, it has a drawback that burrs are easily generated at the connection point of No. 3, and is not suitable for a mold of a fixture for an optical component that requires high accuracy.

Therefore, as a mold for integrally molding the fixture 1 of the present invention, an epoch-making mold which eliminates the various drawbacks in the above-mentioned conventional example is required. In particular, the point is the method of forming the three-point receiving portions (projections 6a to 6c) on the side surface (seat surface) in the die removal direction. Hereinafter, a method of manufacturing the fixture 1 and a mold for integrally molding the fixture 1 will be described.

First, the condition of the protrusion amount (height of the three protrusions 6a to 6c) is that the surface roughness of the molding by the mold is usually 10 μm or less.

Most of the dust that is usually a problem should be 20 μmφ or less.

The ridge of the seat surface (rib) should be 20 μm or less.

In order to satisfy the above conditions, the protrusion amount is 10 to 30 μm.
It will be good if it is about a degree. On the other hand, in order to pull out the undercut on the mold, the amount of protrusion should be small.
Therefore, the protrusion amount of about 30 μm is almost sufficient. or,
Even if it is less than 30 μm, the effect of reducing unstable elements is sufficient.

Next, a method of manufacturing the fixture of the present invention, particularly a method of pulling out the undercut on the integrally-molded die will be described. FIG. 3 is a side sectional view of the fixture 1 which is a molded product and the molding die 10. Mold 10 is fixed mold 1
5 and the movable die 16, and the movable die 16 moves in the direction of the arrow X when the die is removed. During injection molding, the molten molding material is poured into the cavity 9 via the gate 8. In this state, the protrusions 6b and 6c on the molded product are
Becomes an undercut on the mold 16.

By the way, it is known that the molten molding material shrinks when it is radiated and cured. Moreover, the coefficient of linear (body) expansion of the molding material is generally larger than the coefficient of linear (body) expansion of the mold. Therefore, the material cured at the melting point temperature,
If the temperature is further lowered before taking out, as shown in FIG. 4, contraction that is substantially proportional to the temperature decrease occurs. Therefore,
If the sum P (see FIG. 4) of curing shrinkage and temperature shrinkage of the molding material is larger than the undercut amount Q, this undercut can be removed from the mold. This can be expressed as a general formula as follows.

A × B + A × (C−D) × (E−F) ≧ G (1) where A: wall thickness of fixture B: molding shrinkage (shrinkage of molding material upon curing) C: molding material Coefficient of linear expansion D: Coefficient of linear expansion of the mold E: Melting point of the molding material (° C) F: Temperature of taking out from the mold (° C) G: Undercut dimension of protrusions As an actual numerical example, zinc die casting is used as the molding material. (B =
0.002, C = 2.8 × 10 ^-5 , E = 385 ° C, F = 250 ° C), and iron (D = 1.1 × 10 ^-5 ) as the mold material, A
= 3 mm and applying these to the first equation, it becomes 3 × 0.002 + 3 × (2.8-1.1) × 10 ^-5 × (385-250) = 13 μm ≧ G, and it is possible to escape until the undercut amount of 13 μm. Become.

In this case, as shown in FIG. 5 (A), if the undercut side of the protrusion 6 is provided with an inclination 6e in the direction in which the mold easily comes off, the protrusion of the protrusion 6 when the mold is removed. It is less likely to get caught. Further, as shown in FIG. 6B, if the protrusion 6 is formed in a hemispherical shape, the mold can be easily pulled out, and even if the apex of the ball is deformed, the contact area is rapidly increased to stabilize. Will be faster.

Next, a second embodiment of the fixture for the optical component of the present invention will be described with reference to FIG. This attachment 1
As shown in FIG. 6, the feature of ′ is that, from the location of the protrusions 6a and 6b formed on the ribs 5a and 5b, on the side opposite to the drawing direction Y of the mold, the protrusions 6a to 6c are formed. This is where thin ribs 7a and 7b having substantially the same width as the size are formed.
Since these thin ribs 7a and 7b are not undercut,
There is no hindrance to the extraction of the mold, and it becomes easier to extract it. This is effective when the undercut amount G is small where the wall thickness A is small in the above equation (1).
In addition, the possibility that dust larger than the undercut amount of the protrusions 6a to 6c will adhere to the ribs is reduced, for example, a width of 2 mm.
If fine ribs 7a and 7b having a width of 0.1 mm are formed in the ribs 5a and 5b, the probability of dust adhesion will be 1/20 or less.

Since the optical component fixtures 1 and 1'of the present invention are configured as described above, not only countermeasures against the dust 4 and the convex portions 3b but also fixtures due to rust, nests, welds, wrinkles, mold scratches, etc. It is also effective for convex parts of the surface (seat surface) and instability of contact points due to twisting of the surface.

Further, the attachments 1, 1 ′ of the optical component of the present invention are ribs 5
Although description has been made assuming that two a and 5b are formed, the present invention is not limited to this, and three ribs may be formed to form protrusions on each rib, or the ribs may be omitted. In any case, it suffices that the gaps are formed to be slightly narrower than the width of the optical component to be attached and that the three protrusions are not aligned with each other.

〔effect〕

The fixture for the optical component of the present invention is configured as described above, and the fixture is manufactured as described above. Therefore, the drawbacks of the conventional example are eliminated and the following excellent effects are obtained. There is.

Since the optical component is mounted by the three protrusions, it can be installed stably.

The sitting of the optical parts is good, so it is stable against external impact.

Almost no trouble due to dust that is easily sandwiched between the fixture and the optical component.

Since the inclination of the optical component is less likely to occur during and after the attachment, the performance of the optical device equipped with the attachment of the present invention is stable.

Reduced optics failures have improved production yields.

[Brief description of drawings]

FIGS. 1 (A) and 6 are perspective views of the first and second embodiments of the fixture of the optical component of the present invention, and FIG. 1 (B) is the first embodiment of the fixture of the present invention. FIG. 2 is a perspective view showing a state in which an optical component is attached, FIG. 2 is a side sectional view for explaining the features of the fixture of the present invention, and FIGS. 3 and 4 are molding (manufacturing) methods of the fixture of the present invention. 5A and 5B are side cross-sectional views for explaining the present invention, FIG. 5A and FIG.
Figures (A) to (C) are explanatory views showing how to attach an optical component to a conventional fixture, and FIG. 8 is a principle diagram explaining the influence of an angle change in a mirror attached to the present invention and the conventional fixture, 9 (A) to 9 (D) are principle views for explaining an angle instability element when a mirror is attached to a conventional fixture, and FIG. 10 is a sectional view showing an example of a conventional die molding method. is there. 1, 1 '... Fixture, 20 ... Base, 3 ... Seating surface, 3b ...
Projections, 4 ... Dust, 5a, 5b ... Ribs, 6a-6c ... Projections, 7a, 7b ... Thin ribs, 8 ... Gates, 9 ... Cavities, 10
... Mold, 11 ... Mirror, 15 ... Fixed mold, 16 ... Movable mold.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical display location G11B 7/08 Z 8524-5D 7/22 8947-5D // B29L 11:00 4F

Claims (2)

[Claims] 1. A method of manufacturing a fixture for an optical component, wherein three projections are provided on a seat surface for mounting the optical component by a molding method involving heating and cooling using a mold, wherein the seat surface is In the case of the side surface in the drawing direction of the mold, the height G of the above-mentioned three protrusions is calculated by the following formula: A × B + A × (C−D) × (E−F) ≧ G where A: a fixture (seat) Thickness of the surface part) B: Shrinkage ratio during molding and curing C: Linear expansion coefficient of molding material D: Linear expansion coefficient of mold material E: Melting point of molding material F: Temperature at the time of removal from the mold A method for manufacturing a fixture for an optical component, which is characterized by forming the fixture. 2. A fixture for an optical component, which is provided with three protrusions spaced apart from each other on a seat surface for mounting the optical component by a molding method involving heating and cooling using a mold, and is substantially equivalent to the protrusion. A plurality of thin ribs having a width are formed on the seating surface, the three protrusions are formed on the plurality of ribs, and the height G of the three protrusions is calculated by the following formula A × B + A × (C -D) × (E−F) ≧ G where A: wall thickness of fixture (seat surface) B: shrinkage during molding and curing C: linear expansion coefficient of molding material D: linear expansion coefficient of mold material E : Melting point of molding material F: Fixing tool for optical parts, which is formed so as to satisfy the temperature at the time of taking out from the mold.