JPH03181913A - Production of rotary polygonal mirror - Google Patents

Abstract

PURPOSE:To improve the surface accuracy of the side faces to constitute reflecting mirror surfaces by providing compressing mean which moves in the direction perpendicular to the revolving shaft of the rotary polygonal mirror and press welding a resin to the inner side surfaces of side part molds by the compressing means. CONSTITUTION:The means 21 which moves perpendicular to the revolving shaft of the rotary polygonal mirror and compress the injected resin are provided in a part of the molds. The resin is pressurized toward both surfaces of the side parts molds 11 by the compressing means 21 in the curing process of the resin injected and poured into a cavity part 10. Since the transferability of the reflecting mirror surfaces in particular to the molds is improved in this way, the production of the rotary polygonal mirror having the sufficiently high surface accuracy of the reflecting mirror surfaces is executed by using the resin injection molding which allows the reduction of weight and is low in production cost.

Description

[Detailed Description of the Invention] [Summary] Regarding the improvement of a method for manufacturing a rotating polygon mirror by injection molding a resin, the present invention relates to a method for manufacturing a rotating polygon mirror using a resin injection molding method with high surface precision of the side surface that becomes a reflective mirror surface. A method for manufacturing a rotating polygon mirror by injection molding resin into a cavity surrounded by side molds corresponding to the reflective mirror surface to be formed and upper and lower molds. A means for compressing the injected resin by moving perpendicularly to the rotation axis of the rotary polygon mirror is provided in a part of the mold, and the compressing means compresses the resin injected into the cavity during the curing process. A method for manufacturing a rotating polygon mirror in which pressure is applied toward both sides of a side mold, and the compression means is provided near the inner surface of the side mold and slides in a direction perpendicular to the rotation axis. Mix the foam material injected into a second cavity formed near the inner surface of the side mold, either in a moving nest or in a side mold that slides perpendicularly to the rotation axis. This is because of the resin.

[Industrial application field]

The present invention relates to an improvement in the method of manufacturing a rotating polygon mirror by injection molding resin.

[Conventional technology]

A rotating polygon mirror included in an optical device having a laser scanning system is generally a regular polygon with the side surfaces of a prism member formed as a reflective mirror surface. It is used to change the reflection direction of an incident laser beam and scan the laser beam spot on the light receiving surface.

Conventionally, such a rotating polygon mirror is made of optical glass or a metal material such as an aluminum alloy, which is formed into a regular polygonal column by cutting or grinding, and then, when optical glass is used, by polishing. When metal materials are used, they have been manufactured by ultra-precision cutting using a diamond cutting tool to form the side surfaces of the prisms as reflective mirror surfaces.

[Problem to be solved by the invention]

However, the method for manufacturing a rotating polygon mirror using the above method is
There are many steps, and it requires a lot of labor, time, and advanced technology to form prismatic parts through processes such as cutting from optical glass or metal materials, and to form highly accurate reflective mirror surfaces through polishing and cutting treatments. However, there is a problem in that the manufacturing cost is high.

In addition, since rotating polygon mirrors made of metal or glass are heavy, the drive system for high-speed rotation must also be large, which is an obstacle to reducing the weight and size of equipment equipped with rotating polygon mirrors. ing.

In order to solve the above problems, a rotating polygon mirror manufactured by injection molding using resin as a material and a method for manufacturing the same have been proposed (see, for example, Japanese Patent Laid-Open No. 196221/1983). However, if only the general injection molding method is used, the transferability of the resin to the mold that forms the side surfaces of the rotating polygon mirror is insufficient, and the side surfaces will suffer from sink marks, warpage, and curvature, and will not be used as a reflective mirror surface. The drawback was that the surface accuracy was insufficient for use.

To solve this problem, it is possible to compress the resin injected into the cavity of an injection mold from the direction of the rotation axis, which is the method currently used in compact disc molding. Although this method is conceivable, there is a drawback in that this method has little effect on side surfaces that require particularly high surface accuracy.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing a rotating polygon mirror by resin injection molding, in which the side surfaces serving as reflective mirror surfaces have a high surface area.

[Means to solve problems]

In order to solve the above problem, the method for manufacturing a rotating polygon mirror of the present invention includes a side mold (11) corresponding to the reflective mirror surface to be formed, and upper and lower molds (12, 13). A method of manufacturing a rotating polygon mirror by injection molding resin into an enclosed cavity (10), the resin being injected into a part of the mold while moving perpendicularly to the rotation axis of the rotating polygon mirror. In the curing process of the resin injected into the cavity part (10), the compression means pressurizes the resin toward the screen of the side mold. Side mold (11) that forms the reflective surface of the mirror
A nest (21) that has a plane (21A) parallel to the inner surface (11A) and slides in a direction perpendicular to the rotation axis of the rotating polygon mirror is provided near the inner surface (11A) of the polygon mirror. The nest (21) is provided with the same number of reflective mirror surfaces as the inner surface (11A) after resin is injected into the cavity (10).
) side to compress the resin in the cavity portion (10A) near the inner surface (11A), or the injection mold for forming the rotating polygon mirror is as described above. Upper and lower molds (3
2, 33), and at least two side molds (31) which are divided by a plane including the rotation axis and movable in a direction perpendicular to the rotation axis, are placed at the bottom of the tank, and resin is poured into the cavity part (10). The injection process and the upper and lower molds (32
33) compressing the resin in the cavity part (10) from the direction of the rotating shaft, and the side mold (31)
) to compress the resin in the cavity part (10) in a direction perpendicular to the rotation axis, or a side mold ( 11) has a plane (41A) parallel to the inner surface (11A) near the first cavity portion (10A) formed inside the inner surface (11A) of the rotary polygon mirror; The slide core (41) is provided with a slide core (41) that forms a second cavity part (10B) by retracting in the axial direction, and after a certain period of time after injecting the resin into the first cavity part (10A), the slide core (41) is retreated, and a resin mixed with a foaming material is injected into the formed second cavity part (10B) and integrally molded. In order to improve the transferability to the inner surface of the side mold to be formed and to increase the surface precision of the reflecting mirror surface, a compression means that moves in a direction perpendicular to the rotation axis of the rotating polygon mirror is provided. The resin is pressed onto the inner surface of the part mold.

In a second aspect of the present invention, the insert serving as the compression means presses the resin injected near the inner surface to the inner surface by applying pressure from the inside.

The third invention is such that the upper and lower molds compress the resin injected from the circumferential axis direction of the rotating polygon mirror, and the side molds forming the reflective mirror surface of the rotating polygon mirror are directly used as the compression means. Pressure is applied to the injected resin to press the resin against the inner surface.

A fourth aspect of the invention is that after the resin injected into the first cavity near the inner surface has hardened to some extent, the resin mixed with the foaming material is injected into the second cavity having a plane parallel to the inner surface. The resin on the first cavity side is compressed to the inner surface by using the compression means that causes the resin mixed with the foam material to expand due to the foaming action of the injection.

〔Example〕

(al) Description of the First Embodiment The first embodiment will be described with reference to FIGS. 1 to 3.

FIG. 1 is a diagram showing the main parts of the injection mold used in the manufacturing method of this example. The plane perpendicular to the vertical direction (hereinafter referred to as the horizontal plane)
FIG. 1(b) is a plane including the circumferential axis (hereinafter referred to as a vertical plane/line A-A in FIG. 1 al). FIG. FIG. 2 is a diagram showing a drive mechanism for the nest of the injection mold shown in FIG. FIG. 3 is a diagram showing the rotating polygon mirror manufactured according to this example, in which FIG. Yes, Fig. 3 (bl is the vertical plane of the rotating polygon mirror (third
FIG. 2 is a cross-sectional view taken along the line C-C in FIG.

The rotating polygon mirror manufactured in this embodiment is a regular octagonal member as shown in FIG. 3, and the side surface IA of the mirror surface portion 1 is formed as a reflective mirror surface. In addition, as shown in Figure 5, there is an insertion hole 2 in the center for inserting the rotating shaft that drives the rotating polygon mirror.
A boss 3 is formed to form a mirror surface l and a boss 3.
is integrally formed with a plate-shaped portion 4 perpendicular to the rotation axis being interposed therebetween.

Further, 5 is a gap formed by a nest 21 which will be described later.

For example, polycarbon resin is used as the resin material constituting this rotating polygon mirror. This has excellent mechanical strength,
Furthermore, since the transferability to the mold is good, a reflective mirror surface with high surface precision can be obtained.

Next, the injection mold of this embodiment will be explained with reference to FIG. The injection mold of this embodiment includes a plurality of (four in this embodiment) side molds 11 that form the mirror surface of the rotating polygon mirror, and an upper mold 12 that forms the upper part of the rotating polygon mirror. , a lower mold 13 forming the lower part of the rotating polygon mirror.

The upper mold 12 is movable in the vertical direction, and when the resin has finished curing, is pulled upward to remove the molded rotating polygon mirror. Note 1
2A is a portion of the upper mold where the insertion hole 2 for the rotary polygon mirror is formed.

- The gusset mold 13 is fixed to an injection molding device (not shown).

In addition, the side mold 11 is movable in a direction perpendicular to the rotation axis, and when the resin has finished curing, it slides outward to remove the molded rotating polygon mirror without damaging the reflective mirror surface IA. It is made to be removable.

21 is a nest which is a feature of the present invention, and the 111th (a)
The resin is pressed onto the inner surface 11A of the side mold 11 by moving in the direction of the arrow shown in each of 1 and bl.

Next, the drive mechanism of the nest 21 will be explained with reference to FIG.

FIG. 2 shows the line B-B of FIG. 1 (bl) in the left-right direction of the figure, and the injection mold shown in FIG. 1 is omitted in this figure.

51 is a rotating shaft rotated by a drive system (not shown);
52 is a gear connected to the rotating shaft of 51. 53
is a part of the first taper, teeth 53A are formed on the lower surface and engage with teeth 52A formed on the circumference of the gear 52, and a slope 53B is formed on the upper surface. Therefore, the first tapered portion 53 has a wedge shape with a narrow width on the right side and a wide width on the left side. Further, 54 is a second taper part, and since a slope 54A that contacts the first taper part 53B is formed on the lower surface, the overall shape is wedge-shaped, wide on the right side and narrow on the left side. It becomes.

The first tapered portion 53 is slidable in the left-right direction, and the second tapered portion 54 is slidable in the vertical direction.

55 is a sliding portion, which contacts the second taper 54 at 55A. Further, the sliding portion 55 slides in the vertical direction and is biased downward by a biasing force (not shown).

56 is a leg connected to the nest 21, and has eight trees radially arranged, the same number as the nest. This leg portion 56 is connected to the main body 50 of the drive mechanism at a fulcrum 56A. On the other hand, the sliding part 55 is connected to the connecting part 56B, so that when the sliding part 55 slides upward, the connecting part 56B is pushed upward, and the leg part 56 is connected to the tip of the leg. A certain nest 21 opens in the direction shown by the arrow in the figure.

To explain the operation of this embodiment, first, when resin is injected into the cavity 10, the gear 52 is rotated by a certain angle due to the driving force transmitted to the rotating shaft 51 directly connected to a drive system (not shown). This rotation causes the teeth 52 of the gear 52 to
A and the first taper 53 engaged through teeth 53A.
slides to the right. Thereafter, as described above, the second taper 54 and the sliding part 55 in contact with it slide upward, the leg part 56 opens, and the nest 21 at the tip of the leg part 56 moves outward by 0.05 mm. By sliding about 0.1 mm, the resin in the cavity 10A near the inner surface 11A of the side mold 11 is compressed.

As a result, since the resin in the cavity portion 10A is pressed against the inner surface 11A, the transferability to the inner surface 11A is improved, and a rotating polygon mirror with excellent surface precision of the reflecting mirror surface can be molded.

(bl) Description of Second Embodiment The second embodiment will be explained with reference to FIGS. 4 and 5.

FIG. 4 is a diagram showing the main parts of the injection mold used in the manufacturing method of this example, in which fat in FIG. FIG. 4(b) is a cut sectional view taken along a vertical plane (line E-E in FIG. 4 (al)). FIG. 5 shows a rotating polygon mirror manufactured according to this example. Figure 4 (al.
is a cross-sectional view taken along the horizontal plane of the rotating polygon mirror (line H-H in FIG. 5 (bl)), and FIG. FIG. 4 is a cutaway sectional view. In both FIGS. 4 and 5, the same parts as in FIGS. 1 to 3 are designated by the same reference numerals.

The rotating polygon mirror manufactured by the manufacturing method of this embodiment shown in FIG. 5 is the same as the rotating polygon mirror of FIG. 3 manufactured by the above-mentioned first embodiment except that the gap 5 is not formed. It has the shape of

Furthermore, the upper mold of the injection molding mold of this embodiment shown in FIG. It has a sliding structure that compresses it.

The side mold 31 is divided into eight parts, the same number as the reflecting mirror surfaces IA of the rotating polygon mirror, and the outer edge is a side extending upward from the side of the lower mold 33 fixed to an injection molding machine (not shown). It is supported by the mold support part 33A.

Further, the side mold 3I is configured to slide in the direction of the cavity portion 10 by a mechanism similar to the mechanism for sliding the nest 21 in the first embodiment.

That is, the leg portion 34 connected to the side mold 31 corresponds to the leg portion 56 in FIG. 2 of the first embodiment, and contrary to the first embodiment, the leg portion 34 is normally The portion 34 is biased outwardly and is configured to tighten inwardly during the compression process described below.

To explain the operation of this embodiment, the manufacturing process includes: (1) a step of injecting resin into the cavity portion 10; (2) a step of injecting resin into the cavity portion 10;
2 compresses the resin in the cavity 10 in the vertical direction by sliding downward; (2) compressing the resin in the cavity 10 from the side by sliding the side mold 31 toward the cavity 10; It consists of a step of compressing, and (1) a step of taking out the molded rotating polygon mirror from the mold after steps (2) and (2) are completed and the resin is cured.

Of these, steps (1) and (2) are performed while the melted resin is curing, and step (2) may be performed before step (2). Further, the sliding distances of the upper mold and the side mold in steps (1) and (2) are both about 0.05 to 0.1 mm.

In this embodiment, since the resin is pressure-bonded to the inner surface 31A of the side mold 31 that forms the reflective mirror surface in step (3), the transferability to the inner surface 31A is improved, and the rotating polygon surface with excellent surface precision of the reflective mirror surface is obtained. The mirror can be made into a bottom shape.

(C) Description of the third embodiment The third embodiment will be explained with reference to FIGS. 6 and 7.

FIG. 6 is a diagram showing the main parts of the injection mold used in the manufacturing method of this example, in which FIG. FIG. Fig. 6(b), (C1 is a cross-sectional view taken along the vertical plane (line -G in Fig. 4(a));
6(C) is a diagram showing a process of injecting resin into the first cavity part 10A, and FIG. 6(C) is a diagram showing a process of injecting resin mixed with a foaming material into the second cavity part.

9 FIG. 7 is a diagram showing the rotating polygon mirror manufactured according to this example, of which FIG. 6 1al shows the horizontal plane (7th
FIG. 7(b) is a cross-sectional view cut along the vertical plane of the rotating polygon mirror (line LL in FIG. 7(b)). In both FIGS. 6 and 7, the same parts as in FIGS. 1 to 5 are designated by the same reference numerals.

The rotating polygon mirror manufactured by the manufacturing method of this embodiment shown in FIG.
A resin portion 6 mixed with a foamed material having an octagonal column shape and having a plane parallel to is formed.

The injection mold of this embodiment shown in FIG. 6 includes an upper mold 12 that can be pulled out upwards as in the first embodiment, a lower mold 13 fixed to an injection molding machine (not shown), In addition to the four-part side mold 11 that is extracted in a direction perpendicular to the circumferential axis, the structure includes a slide core 41 that is a feature of the present invention.

As shown in FIG.
The lower mold 13 is divided into a cavity part 10A on the inner surface 11A side of the side mold 11 and a cavity part 10C in the center part.As shown in FIG. A cavity portion 10B is formed by being drawn into a pocket 13A provided in the pocket 13A.

To explain the operation of this embodiment, first, as shown in the sixth opening, the slide core 41 injects resin into the cavities 10A and 10C while being positioned upward.

When the injected resin hardens, the slide core 41 retreats into the pocket 13A, forming a cavity 10B as shown in FIG. 6 (TO). A resin mixed with a foaming material is injected into this cavity portion 10B. When the resin is cured, the resin is not completely cured, but the cavity part 10
This refers to a state in which the material has hardened to the extent that it does not block B.

The resin mixed with the foaming material injected into the cavity part 10B foams and expands, causing the cavity part 1
The resin in 0A is compressed toward the inner surface 11A of the side mold 11.

Therefore, the resin side mold 11A inside the cavity part 10A
It is possible to form a rotating polygon mirror with excellent surface precision of the reflecting mirror surface.

In this embodiment, the shape of the resin part 6 mixed with the foam material (the shape of the slide core) may be formed of a plane parallel to the mirror surface IA as described above, but the resin part 6 mixed with the foam material may Since the mechanical strength is inferior to that of ordinary resin, the proportion of the resin portion 6 mixed with the foam material in the rotating polygon mirror may be determined by taking into consideration this strength and the above-mentioned transferability.

In each of the first to third embodiments above, a regular octagonal prism-shaped rotating polygon mirror was explained as an example, but of course, other polygonal prism-shaped (for example, regular hexagonal prism) rotating polygon mirrors can also be used as shown in the above embodiments. Manufacturing methods can be applied.

In addition to the above-mentioned embodiments, various methods such as using an air chamber may be used to compress the resin injected into the cavity toward the inner surface of the side mold during the curing process. You can also do that.

Incidentally, the reflectance of the rotating polygon mirror manufactured according to each of the above embodiments can be further increased by depositing a metal coating such as aluminum on A to form a reflection-increasing coating, and then forming a protective coating on top of this. A highly rotating polygon mirror can be obtained.

〔Effect of the invention〕

As explained above, according to the present invention, the transferability of the reflective mirror surface to the mold is particularly improved, so resin injection molding, which can be lightweight and has low manufacturing costs, can be used, and the reflective A method for manufacturing a rotating polygon mirror with a sufficiently high mirror surface area can be realized.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the injection mold of the first embodiment, 3 Fig. 2 is a diagram showing the drive mechanism of the insert 2I in Fig. 1, and Fig. 3 is a diagram showing the injection mold of the first embodiment. FIG. 4 is a diagram showing an injection molding mold of the second embodiment. FIG. 5 is a diagram showing a rotating polygon mirror manufactured according to the second embodiment. FIG. 7 is a diagram showing an injection molding die of the second embodiment, and FIG. 7 is a diagram showing a rotating polygon mirror manufactured by the second embodiment. In the figure, 1- mirror surface part, 2- insertion hole, 3- boss part, 4- plate-like part, 5- gap part, 6- resin part mixed with foam material, 10- cavity part, 11. 31- side part Mold, 12.32-1 Upper mold, 4 13゜3 Lower mold, 1 Nest, 1 Slide core. (Q) Ho plane tga#r#r1 button ■ JP-A-3 181913 (8) LLl+1 LL<J Esshi!・- J-ya”

Claims (4)

[Claims] (1) Side mold (11) corresponding to the reflective mirror surface to be formed
A method for manufacturing a rotating polygon mirror by injection molding a resin into a cavity portion (10) surrounded by upper and lower molds (12, 13), the method comprising the steps of: A means for compressing the injected resin by moving perpendicular to the rotation axis is provided, and the cavity part (
10) A method for manufacturing a rotating polygon mirror, characterized in that during the curing process of the injected resin, the compression means pressurizes the resin toward both sides of the side mold. (2) Side mold (11
) near the inner surface (11A) of the inner surface (11A).
The number of inserts (21) having a plane (21A) parallel to the mirror and sliding in a direction perpendicular to the rotation axis of the rotating polygon mirror is the same as the number of reflecting mirror surfaces, and resin is injected into the cavity part (10). After that, the nest (21) slides toward the inner surface (11A), thereby opening the cavity portion (10A) near the inner surface (11A).
) A method for manufacturing a rotating polygon mirror, characterized by compressing resin in the interior. (3) The injection mold for forming the rotating polygon mirror is divided into upper and lower molds (32 , 33) and at least two side molds (31) that are divided by a plane including the rotation axis and movable in a direction perpendicular to the rotation axis, and inject resin into the cavity part (10). a step of compressing the resin in the cavity part (10) from the direction of the rotating shaft by the upper and lower molds (32, 33); and compressing the resin in the cavity part (10) by the side molds (31) 10) A method for manufacturing a rotating polygon mirror, comprising the step of compressing the resin in a direction perpendicular to the rotation axis. (4) Side mold (11
) has a plane (41A) parallel to the inner surface (11A) in the vicinity of the first cavity portion (10A) formed inside the inner surface (11A) of the rotary polygon mirror; The second cavity part (10B
), and after a certain period of time after injecting the resin into the first cavity part (10A), the slide core (41) retreats to form a second cavity part (10A). 10B) A method for manufacturing a rotating polygon mirror, characterized in that the polygon mirror is integrally molded by injecting a resin mixed with a foaming material.