JPH0996711A - Rotary polyhedral mirror made of synthetic resin and production of rotary polyhedral mirror made of synthetic resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotary polyhedral mirror made of a synthetic resin which is improved in the flatness of reflection surfaces by making the temp. distribution on the reflection surfaces after parting from molds uniform and obviates the occurrence of unequal rotation by high-speed rotation. SOLUTION: The upper surface of a body 51 having flanks 516 which becomes the reflection surfaces is projectingly provided with a placing section 53 which is specified in the size of a height direction nearly to 10% of the plate thickness of the body and to nearly 5mm in the spacing between the external shape line thereof and the external shape line of the body. The placing section 53 is cooled in the state of bringing this section into contact with the surface of the flat plate in a cooling stage. The flanks 516 which are the reflection surfaces are rested in the air without coming into contact with any point in the cooling and, therefore, the temp. fall state to the height direction of the flanks is made uniform and the degree of shrinkage of the resin is made uniform. The flat plate on which the synthetic resin member formed by molding is placed and which cools this member is otherwise projectingly provided with a projection for placement to avert the contact of the flanks which are the reflection surfaces and to make the temp. fall state uniform.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary polygon mirror made of synthetic resin for rotationally deflecting and scanning incident light and a method for manufacturing the rotary polygon mirror.

[0002]

2. Description of the Related Art Japanese Unexamined Patent Publication No. 63-304225 and Japanese Unexamined Patent Publication No. 7-180429 disclose prior arts for improving the flatness of a reflecting surface of a rotary polygon mirror.

[0003]

The conventional rotary polygon mirror made of synthetic resin has a mounting reference plane 1 as shown in FIGS.
0 or the mounting end surface 13 is formed as a flat surface extending vertically from the end of the reflecting surface 15. Alternatively, FIG.
As shown in FIG. 6, the rotary shaft insertion hole 20 and the polygonal reflection surface portion 2
1 are connected by the plate body 23, and the boss portion 25 for reinforcement is formed. These polygonal mirrors were configured to prevent sink marks and improve flatness. At the same time, this is aimed at weight reduction for reducing the rotational load on the scanner, but in particular, the latter has a problem that it cannot withstand centrifugal force during high-speed rotation. Further, except in special cases such as cooling to room temperature in the mold, in the left state after molding and releasing, in the former rotary polygonal mirror made of synthetic resin, the side surface end which becomes the reflecting surface 15 is directly I got in touch with something. For this reason, there was a difference in the cooling rate due to heat conduction between the contact portion and the non-contact portion (state left in the air). Due to this partial difference in the cooling rate of the resin, a phenomenon in which the rate of resin shrinkage varies, and the uneven shrinkage has been a factor of deteriorating the flatness of the reflecting surface. Further, the latter rotary polygon mirror made of synthetic resin has a reflective surface portion 2
Since the plate thickness of No. 1 is different between the portion b having the connecting plate body 23 and the portion a not having the connecting plate body 23, the cooling rate of the reflection surface portion 21 also has a difference, the contraction rate of the resin and the temperature distribution change, and The flatness was adversely affected.

In recent years, as the resolution of copying machines and laser beam printers has increased, there has been a demand for higher precision in the reflecting surface of the rotary polygon mirror. At the same time, by making this rotary polygon mirror made of synthetic resin, it is expected that the manufacturing cost will be significantly reduced as compared with the conventional metal rotary polygon mirror. Also,
Since the accuracy of the rotating polygon mirror directly affects the print quality,
Ultra-precision precision is required, and ensuring the precision of the flatness of the reflecting surface is an important issue. When this rotary polygon mirror is manufactured from synthetic resin, the product during molding is generally exposed to air at room temperature by releasing from a high mold temperature (near the glass transition point). After that, the product is placed on a tray or the like so as to be stocked. Even when the product is placed on this tray, the product shrinks as the resin cools. However, in order to uniformly shrink the product after releasing the mold and to improve the flatness of the reflecting surface, at least the temperature distribution of the reflecting surface after the releasing must be uniform. However, when placed on a tray or the like and cooled, the temperature of the reflection surface becomes non-uniform due to the reflection surface being in direct contact with the tray, the difference in plate thickness, or the like. This non-uniform cooling caused the shrinkage speed of the resin to be partially different, and as a result, the shrinkage speed changed depending on the location and adversely affected the flatness of the reflecting surface.

According to the present invention, the flatness of the reflecting surface is improved by making the temperature distribution of the reflecting surface after releasing the mold uniform,
Provided is a method for manufacturing a synthetic resin rotary polygonal mirror having no rotational unevenness even at high speed rotation, and a synthetic resin rotary polygonal mirror having good quality.

[0006]

A method of manufacturing a rotary polygon mirror made of synthetic resin according to the present invention has a main body having a fitting hole for a rotary shaft and a plurality of side surfaces serving as reflecting surfaces formed on an outer peripheral surface. When,
A molding process that projects in the axial direction from the axial end face of the main body and that forms a rotary polyhedron with a mounting portion having an end face that is orthogonal to the fitting hole of the rotary shaft by molding the synthetic resin material. The end surface of the mounting part that projects the molded synthetic resin member from the main body is mounted on a flat plate, and the side surface that is the reflection surface of the main body is separated from the flat plate surface by the thickness dimension of the mounting part, and the temperature of the synthetic resin member Basically, a cooling step of lowering the temperature to a prescribed temperature and a vapor deposition step of forming a reflective surface by coating on the side surface to be the reflective surface.

Furthermore, the ratio of the thickness of the mounting portion of the molded synthetic resin member to the thickness of the main body is 10%.
A configuration may be provided such that the front and rear or the interval between the outline of the mounting portion and the outline of the main body is approximately 5 mm. In addition, the leaving plate of the synthetic resin member in the cooling step is provided with a mounting protrusion for mounting the synthetic resin member, and the synthetic resin member is mounted and cooled on the mounting protrusion, and the mounting protrusion has a cooling mechanism. May be connected.

A rotary polygon mirror made of synthetic resin according to the present invention comprises a main body having a plurality of reflecting surfaces formed on an outer peripheral surface thereof, having a fitting hole for a rotary shaft, and an axial end surface of the reflecting surfaces of the main body. A mounting portion protruding in the axial direction (the ratio of the thickness of the mounting portion to the thickness of the main body is about 10%, and the distance between the outline of the mounting portion and the outline of the main body is about 5 mm. ) And the end surface of the mounting portion is a plane orthogonal to the fitting hole of the rotating shaft.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments of the present invention will be described below with reference to the drawings. First Embodiment FIG. 1 is a perspective view of a rotary polygon mirror, and FIG. 2 is a side view. The rotating polyhedron 50 integrally includes a main body 51 having a polygonal outer shape formed of a synthetic resin body and a mounting portion 53 having a similar shape to the main body at the upper portion of the main body. 5
5 are perforated. The main body 51 has a mounting reference surface 512 to be mounted on the rotor and a mounting end surface 514 opposite to the mounting reference surface 512 arranged in parallel, and has a reflection surface perpendicular to both surfaces connecting the mounting reference surface 512 and the mounting end surface 514. The side surface 516 is formed. The illustrated main body 51 is an octahedron. The plate thickness of the main body 51 is set to H. The mounting portion 53 has a shape substantially similar to the shape of the main body 51, and its height dimension is h
And Here, the height dimension h of the mounting portion 53 is formed so as to be within a range satisfying approximately 10% of the plate thickness dimension H of the main body 51. The plate thickness dimension H of the main body 51 and the height dimension h of the mounting portion 53 influence the thickness balance of the entire rotary polyhedron 50 and the flatness accuracy of the reflecting surface. For example, when the plate thickness dimension H of the main body 51 is 4.4 mm, the height dimension h of the mounting portion 53 is set to about 0.4 mm. Further, the placement position of the mounting portion 53 with respect to the main body 51 is determined by
The distance f between the outline of No. 1 (the edge of the side surface 516 serving as the reflecting surface) and the outline of the mounting portion 53 is set to approximately 5 mm. For example, when the longest width dimension R of the main body 51 is 34 mm, the longest width dimension r of the mounting portion 53 is approximately 24 mm. The side surface 516 of the rotating polyhedron 50 configured as described above is mirror-finished to form a reflection surface 51.
6K, and the rotating polygon mirror 500.

Next, attachment of the synthetic resin rotary polygon mirror to the scanner motor will be described (see FIG. 3). The rotary shaft 70 of the scanner motor is fitted into the fitting hole 55 of the rotary polygon mirror 500, and the rotary polygon mirror 500 is mounted on the pedestal 40 rotatably attached to the housing 43 via the bearing 45.
Mount the mounting reference surface 512 of. The top of the mounting portion 53 is pressed by the leaf spring 47. Here, reference numeral 41 indicates a printed circuit board. As described above, the rotary polygon mirror 500 attached to the scanner motor is held between the spring 47 that presses the upper surface and the receiving pedestal 40, rotates, and reflects light at the reflecting surface 516K.

Next, a method of manufacturing the rotary polygon mirror 500 made of synthetic resin will be described. Molding Step A molten synthetic resin material is injected into a mold to form a synthetic resin member (rotary polyhedron) 50 having an octagonal main body 51 and a mounting portion 53 having a similar shape to the main body 51.

Cooling Step A rotary polyhedron 50, which is a molded product, is taken out of the mold and left on a flat plate, for example, a glass flat plate 100, with the rotary polyhedron mounting portion 53 as the lower surface, and cooled. About 6 hours
It is about time. FIG. 4 shows a conceptual diagram of a cooling state when the synthetic resin body is mounted as described above. According to this figure, it is considered that the temperature distribution of the side surface 516, which is the reflecting surface, of the rotating polyhedron 50 is constant (uniform) in the height direction H. On the other hand, as shown in FIG. 5, it is considered that the temperature distribution of the side surface 15a serving as the reflection surface of the conventional rotating polyhedron 10 is higher in the plate thickness direction (height direction H) of the rotating polyhedron 10. To be That is, the conventional rotating polyhedron 1
0 is left on the surface of the flat plate 100 such as glass directly in the high temperature state immediately after the mold release, so that the cooling rate is low in the low portion in contact with the flat plate 100, and as the distance from the flat plate 100 increases,
Cooling rate is slow.

The rotating polyhedron 50 according to this embodiment is
Since the main body 51 is placed on the flat plate 100 via the placement surface 53 without directly contacting the flat plate 100 in the state after being released from the mold, the side surface 516 serving as a reflection surface does not contact anything. Left in the air. Therefore, the temperature drop rate of the side surface 516 serving as the reflection surface becomes uniform in the height direction, and the side surface 5
The temperature distribution of 16 and the resin cooling are uniform.

Here, the thickness dimension of the main body 51 and the mounting portion 53
The flatness of the mirror surface with respect to the ratio of the thickness dimension was measured. The result is shown in the graph of FIG. In this graph, the vertical axis represents the flatness of the mirror surface (unit λ · 1λ = 0.6328 μm),
The horizontal axis represents the ratio (%) of the thickness dimension of the mounting portion to the thickness dimension of the main body. Samples A, B, C, D, and E each have three rotating polyhedra each having a hexahedron as a main body and a mounting portion, and the average flatness of each surface of each sample is displayed as a symbol. Is displayed as a straight line. Here, in the case of the sample A having a recessed mounting portion, in the case of sample B not having the mounting portion formed thereon and when the main body is directly mounted on a flat plate and cooled, the sample C has a thickness dimension of the mounting portion. Is 6.25% of the thickness of the main body, Sample D is 21.25% of the thickness of the main body when sample thickness is 21.25%, and Sample E is the thickness of the mounting portion. Is 23.75% of the thickness of the main body, and is the flatness of the mirror surface in a state where the mounting portion is mounted on a flat plate and cooled.

Looking at this graph, it is shown that Sample C and Sample D have good flatness. That is, the thickness dimension of the placing portion 53 is formed in the range of 6.25% to 21.25% with respect to the thickness dimension of the main body 51, and the placing portion 53 is placed on a flat plate and cooled. As a result, it can be seen that the cooling temperature on the side surface to be the mirror surface is made uniform.
However, when the thickness of the mounting portion 53 is increased, the total thickness of the central portion and the side portions of the rotating polyhedron becomes unbalanced, and the central portion having a large plate thickness is not uniformly cooled. From this point of view, in the rotary polyhedron 50 in this embodiment, the plate thickness of the mounting portion 53 is set to about 10% of the plate thickness of the main body.

Vapor Deposition Process Step A metal coating film is vapor deposited on the side surface 516 of the cooled rotating polyhedron 50 which serves as a reflection surface. The side surface 516 serving as a reflecting surface serves as a reflecting surface and reflects, for example, laser light with polarization. As described above, the rotary polygon mirror according to this embodiment has a uniform temperature distribution on the side surface to be the reflecting surface after release, uniform resin shrinkage, and good flatness of the reflecting surface. It becomes a resin polygon mirror. Also, increase the thickness of the center of rotation,
Since the thickness of the other portion is thinly formed, and for example, the convex portion of the central portion is made uniform to about 10% of the thickness of the side surface with respect to the side surface to be the reflection surface, the overall thickness balance is good,
No uneven rotation occurs due to high speed rotation.

In addition to the above, the following shapes can be formed as the rotary polygon mirror. (A) A convex surface corresponding to a mounting surface is formed on both surfaces of the main body 51. ...... Refer to FIG. 7. A reference surface side convex surface 53A is formed on the mounting reference surface 512 of the main body 51, and a mounting end surface side convex surface 530A is formed on the mounting end surface 514 side.
In this rotary polyhedron 50A, either convex surface may be used as the mounting surface when left standing after the mold is released. (B) The mounting surface has a trapezoidal shape. ... Figures 8, 9, and 1
Reference 0 A trapezoidal mounting surface 53B is formed on the mounting end surface side of the main body 51B. The trapezoidal mounting surface 53B includes a mounting portion 530B orthogonal to the fitting hole 55 of the rotary shaft, an end of the main body 51B, and the mounting portion 5.
It is composed of an inclined side surface 531B connecting the 30B end edge,
The distance between the edge of the main body 51B and the edge of the mounting portion 530B is approximately 5
mm. Also in this shape, as shown in FIG. 10, the first mounting portion 53C and the second mounting portion 53C are provided on both surfaces of the main body 51C.
The mounting portion 530C can be formed. (C) The mounting surface is circular, see FIG. 11. The mounting surface 53D formed on the upper surface of the main body 51D is circular with the fitting hole 55 of the rotating shaft being concentric. The rotary polyhedron 50D thus configured has a simple mold configuration. The shape of the rotating polyhedron described above must maintain symmetry as a product in order to rotate at a high speed with good balance. Therefore, any shape is a shape that spreads radially around the fitting hole of the rotating shaft.

Second Embodiment In this embodiment, the contraction of the synthetic resin material during the cooling process is made uniform without changing the shape of the rotary polygon mirror, and the flatness of the reflecting surface is improved. There is. A method of manufacturing the rotary polygon mirror according to this mode will be described (see FIG. 12). Molding Step A molten synthetic resin material is injected into a mold to form a synthetic resin member (rotary polyhedron) 60 having a plate thickness of thickness H.

Cooling Step The molded product and the rotating polyhedron 60 are taken out from the mold and left on the plate 2.
Place it on 00. The standing plate 200 has a plurality of mounting protrusions 250 on which molded articles are placed. The mounting protrusion 250 is a protrusion having a circular cross section, and the size thereof conforms to the size of the mounting surface for the rotating polyhedron described in the first embodiment. For example, the diameter r ₁ of the mounting projection 250 is set such that the outer edge portion of the rotary polyhedron 60 projects substantially by the dimension f ₁ when the rotary polyhedron 60 is mounted. Here, the dimension f ₁ is equal to the difference dimension f between the outer shape of the body of the rotating polyhedron and the mounting surface described in the first embodiment, which is about 5 mm. The standing plate 200 is formed of, for example, a glass plate or the like. The rotating polyhedron 250 is left on the standing plate 200 (about 6 hours) and cooled.
Also in the rotating polyhedron 60 according to this embodiment, the side surface 65 portion that is the reflecting surface of the rotating polyhedron 60 does not directly contact the standing plate 200 in the standing state after release from the mold, and the standing plate is placed via the mounting projection 250. Since it is placed on 200, the side surface 65 serving as a reflecting surface is left in the air without contacting anything. Therefore, the temperature drop rate in the plate thickness direction of the side surface 65 serving as the reflection surface becomes uniform, and the temperature distribution, the resin cooling,
And the shrinkage becomes uniform. Further, since the dimension f ₁ of the side surface portion of the rotary polyhedron 60 protruding from the mounting protrusion 250 is set to about 5 mm like the dimension f, even if it is left for a long time,
The rotating polyhedron does not deform.

Vapor Deposition Process Step A metal coating film is vapor-deposited on the side surface 65 of the cooled rotating polyhedron 60 which serves as a reflection surface. The side surface 65 serves as a reflecting surface and reflects, for example, the laser light by polarization. As described above, the rotary polygon mirror according to this embodiment has a uniform temperature distribution on the side surface that becomes the reflecting surface after release, and the resin shrinkage is uniform, so that the flatness of the reflecting surface is good. It becomes a polygonal mirror made of various synthetic resins. Moreover, since the thickness orthogonal to the fitting hole of the rotating shaft of the polyhedron is made uniform, it is possible to rotate at high speed with good balance. Further, since the mounting projection of the leaving plate has a predetermined size with respect to the rotating polyhedron, even if it is left for a long time, the side surface portion of the rotating polyhedron protruding beyond the mounting projection causes shape deformation. Never.

FIG. 13 shows another example of the leaving plate 270. The mounting protrusion 2 formed on the leaving plate 270 shown in this figure
75 has a cooling function. The placing protrusion 275 of the standing plate 270 has a hollow shape and is connected to a temperature adjusting means such as an air blower arranged outside by a connecting pipe 277. For example, when the room temperature to be left is 23 ° C., the molded product (rotary polyhedron) 60 immediately after being taken out from the molding machine has a very high temperature near the glass transition point. Therefore, the mounting protrusion 27
There is a temperature difference between the contact portion 62 of the rotating polyhedron 60 that is in contact with 5 and the portion 64 that is in contact with air. The resin causes a difference in shrinkage due to the difference in cooling temperature, and this difference in shrinkage may affect the side surface portion serving as the reflecting surface. Therefore, the temperature of the contact portion 62 and the non-contact portion 64 is adjusted by operating the temperature adjusting means and blowing cooling air into the mounting protrusion 275, for example. By configuring the mounting protrusion 275 in this way, it is possible to eliminate the temperature difference due to the portion of the rotating polyhedron 60 and to make the resin shrinkage uniform throughout.
It is possible to obtain a molded article having a high side surface (reflection surface) precision without being affected by heat shrinkage.

As described above, according to the structure of the present invention, when the reflecting surface is left in the air after being released from the mold without being in contact with anything, the temperature distribution in the vicinity of the side surface to be the reflecting surface is improved. It becomes possible to make it uniform. As a result, the resin can be cooled uniformly and the flatness of the reflecting surface can be improved.

[0023]

The rotary polygonal mirror made of synthetic resin of the present invention is a polygonal mirror having a reflecting mirror surface with high plane accuracy, good quality, and high-speed rotation and high durability. Further, in the method for manufacturing a rotary polygon mirror of the present invention, the side surface to be the reflecting surface after taking out the molded product is uniformly exposed to the air, so that the side surface to be the reflecting surface can be uniformly cooled. Furthermore, it is possible to prevent uneven resin shrinkage due to uneven cooling, and it is possible to manufacture a rotary polygon mirror made of resin with a good flatness of the reflecting surface.

[Brief description of drawings]

FIG. 1 is a perspective view of a rotary polygon mirror made of synthetic resin.

FIG. 2 is a side view of a synthetic resin rotary polygon mirror.

FIG. 3 is a cross-sectional view of a rotary polygon mirror arranged on a scanner motor.

FIG. 4 is an explanatory diagram illustrating a mounted state of a rotating polyhedron.

FIG. 5 is an explanatory view illustrating a mounting state of a conventional rotating polyhedron.

FIG. 6 is a graph showing the relationship between the flatness and the ratio of the plate thickness of the mounting portion to the plate thickness of the main body.

FIG. 7 is a side view of another rotary polygon mirror according to the present invention.

FIG. 8 is a perspective view of another rotary polygon mirror according to the present invention.

FIG. 9 is a side view of another rotary polygon mirror according to the present invention.

FIG. 10 is a side view of another rotary polygon mirror according to the present invention.

FIG. 11 is a perspective view of another rotary polygon mirror according to the present invention.

FIG. 12 is an explanatory diagram of another embodiment according to the present invention.

FIG. 13 is an explanatory diagram of another embodiment according to the present invention.

FIG. 14 is a perspective view of a conventional rotary polygon mirror.

FIG. 15 is a side view of a conventional rotary polygon mirror.

FIG. 16 is a side view of a conventional rotary polygon mirror.

[Explanation of symbols]

50, 60 synthetic resin body (rotary polyhedron), 51 main body, 53 mounting portion, 55 fitting hole, 100 flat plate,
200 standing plate, 250 mounting protrusion, 500 rotating polygon mirror, 516 side surface to be reflective surface.

Claims (9)

[Claims] 1. A method for producing a rotary polygonal mirror having a plurality of reflecting surfaces formed on an outer peripheral surface thereof, which has a fitting hole for a rotating shaft, by molding a synthetic resin material. Molding process for molding a synthetic resin member having a main body having a side surface and a mounting portion projecting in the axial direction from the axial end surface of the main body and having an end surface substantially orthogonal to the fitting hole of the rotary shaft. Steps, a cooling step of placing the end surface of the mounting portion projecting the molded synthetic resin member from the main body on a flat plate to lower the temperature of the synthetic resin member to a specified temperature, and a side surface to be a reflecting surface. A vapor deposition step of forming a reflective surface,
In the cooling step, the synthetic resin member placed on the flat plate is a synthetic resin rotary polygonal mirror that is cooled in a state where the side surface to be the reflecting surface of the main body is separated from the flat plate surface by the thickness dimension of the placing portion. Production method. 2. The method for manufacturing a rotary polygon mirror made of synthetic resin according to claim 1, wherein the ratio of the thickness of the mounting portion to the thickness of the main body is about 10%. 3. The method for manufacturing a rotary polygon mirror made of synthetic resin according to claim 1, wherein the interval between the outline of the mounting portion and the outline of the main body is approximately 5 mm. 4. A method of manufacturing a rotary polygon mirror having a plurality of reflecting surfaces formed on an outer peripheral surface by molding a synthetic resin material, wherein a synthetic resin member having a side surface to be a reflecting surface is molded. A molding step of processing and a cooling step of placing the molded synthetic resin member on the standing plate so that the side surface of the molded resin member does not contact the standing plate and lowering the temperature of the synthetic resin member to a specified temperature. A method for manufacturing a rotary polygon mirror made of synthetic resin. 5. The leaving plate of the synthetic resin member in the cooling step is provided with a mounting protrusion having a size capable of supporting approximately 5 mm inside the outline of the synthetic resin member, and the synthetic resin member is mounted on the mounting protrusion. The method for manufacturing a rotary polygon mirror made of synthetic resin according to claim 4, which is placed and cooled. 6. The method for manufacturing a rotary polygon mirror made of synthetic resin according to claim 4, wherein the placing projection of the leaving plate has a temperature adjusting mechanism. 7. A main body having a plurality of reflecting surfaces formed on an outer peripheral surface thereof, which has a fitting hole for a rotary shaft, and a mounting body which projects in an axial direction from an axial edge of the reflecting surface of the main body. A rotary polygon mirror made of synthetic resin having a portion, and the end surface of the mounting portion is a plane orthogonal to the fitting hole of the rotating shaft. 8. The rotary polygon mirror made of synthetic resin according to claim 7, wherein the ratio of the thickness of the mounting portion to the thickness of the main body is about 10%. 9. The rotary polygon mirror made of synthetic resin according to claim 7, wherein the interval between the outline of the mounting portion and the outline of the main body is approximately 5 mm.