JPH067228B2 - Rotating polygon mirror mounting base - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a rotary polygon mirror mounting pedestal that can be easily mounted and whose mutual radial differences can be minimized.

[Prior Art] As a conventional mounting base for a rotary polygon mirror, there is, for example, one shown in FIG. 5 and FIG. 6 used in an optical system of a laser recording apparatus, and each hexagonal peripheral surface is mirror-finished. And a rotary polygon mirror 1 having a mounting hole 2 in the center,
The rotary polygon mirror 1 is attached to the lower part, and a flange portion 3 is provided at a portion facing the bottom surface of the rotary polygon mirror 1.
Further, the mounting pedestal 5 provided with a shaft portion 4 in contact with the inner peripheral surface of the rotary polygonal mirror 1, and the rotary polygonal mirror 1 is fitted into the rotation center of the mounting pedestal 5 and driven by a driving type (not shown). The rotary shaft 6 and the fixing member 8 for fixing the rotary polygon mirror 1 to the mounting base 5 with the fixing screw 7. In the above configuration, the mounting hole 2 of the rotary polygon mirror 1 is fitted into the shaft portion 4 of the mounting pedestal 5 installed in advance in the main body, and the bottom surface of the rotary polygon mirror 1 is placed on the flange portion 3. Then, after mounting the fixing member 8 on the upper part of the mounting hole 2 from the upper surface of the rotary polygon mirror 1,
The fixing screw 7 is inserted through a mounting hole provided at the center of the fixing member 8 and screwed into a screw hole formed on the top of the rotary shaft 6. As a result, the rotary polygon mirror 1 is fixedly arranged by the mounting base 5 and the fixing member 8. The inner diameter of the mounting hole 2 of the rotary polygonal mirror 1 needs to have a gap of 10 μm or more with respect to the outer diameter of the shaft portion 4 in order to facilitate the work of fitting into the shaft portion 4.

[Problems to be Solved by the Invention] However, in the conventional rotary polygon mirror mounting pedestal, if the distance between the mounting hole 2 and the shaft portion 4 is increased in order to facilitate the device of the rotary polygon mirror, the rotary polygon mirror will rotate. Since the center of the shaft 6 and the center of the rotary polygon mirror are displaced, a mutual difference in radius (variation in distance from the rotation center of the rotary polygon mirror to each reflection surface) occurs.
There is a problem in that the reflection position of the light beam on each reflection surface fluctuates in the radial direction, and the scanning speed varies.

As a result, the optical scanning end portion changes for each scanning. That is, as shown in FIG. 7, when a light beam is incident from the light source A, this beam is emitted at an angle θ at the scanning angle where a certain mirror surface (F1) of the rotary polygon mirror 1 exists. If more mirror (F1) of the light beam reflected by the reflecting surface passes through the shortest distance is d, the scanning of the scanning angle in the θ ranging incident side point A and the exit side point B ₁ of the light beam dwell in this distance d The width l ₁ is expressed by the following equation.

l ₁ = 2 dtan θ / 2 (1) On the other hand, on the mirror surface (F2) having a deviation of + Δr with respect to the regular distance r of the rotation center of the rotary polygon mirror 1 to the reflection mirror surface, the reflection surface of the light beam is Move to (d-Δr).
If the incident position in this case is the same as described above, the scanning distance to the scanning end point B ₂ is l ₂ , which is represented by the following equation.

l ₂ = (d-Δr) tan θ / 2 = 2dtan θ / 2-2Δrtan θ / 2 (2) As is clear from the comparison between this equation (2) and the above equation (1), the scanning width l ₂ Is shortened by 2Δrtan θ with respect to l ₁ . That is, this deviation (difference between radii) causes a deviation at the end point of scanning, which deteriorates the recording image quality. Further, since fixing members such as the fixing screw 7 and the fixing member 8 are used for actually fixing the rotary polygon mirror 1, a complicated fixing work using a fixing tool is required and an unreasonable tightening of the fixing screw 7 is required. When stress is applied, there is a risk that the joint portion with the fixed shaft 6 may be deformed or the fixing member may be damaged.

[Means for Solving the Problems] Therefore, in the present invention, the tips of the plurality of columnar bodies are bent toward the center of rotation at a height position corresponding to the depth of the mounting hole of the rotary polygon mirror. The columnar body is formed of a shape memory alloy whose shape is recorded in a state in which the columnar body is expanded outside the mounting hole, and each of the columnar bodies is mounted in the mounting hole while the claw portion is housed in the mounting hole. After being fitted in the hole, the rotary polygon mirror is fixed by recovering the shape.

[Operation] According to the rotary polygon mirror mounting pedestal, when the shape memory is heated, the memory shape is restored, that is, the shape is restored to a state in which each of the columnar bodies is expanded outside the mounting hole. In the above process, the rotary polygon mirror can be fixed very easily with no space between the rotary polygon mirror and the rotary polygon mirror, whereby the above-mentioned problems can be solved all at once.

Embodiments Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is a perspective view of a rotary polygon mirror mounting base according to the present invention.
The configuration example is shown in association with the arrangement of the rotary polygon mirror 1. In FIG. 1, a rotary polygon mirror mount pedestal 50, which also has a rotation center on a straight line G passing through the rotation center of the rotary polygon mirror 1, has a mounting hole 2 provided at the center of the rotary polygon mirror 1, for example. Circular pedestal plate 51 having a wider area
Above the mounting hole 2 drawn around the center of rotation
Are arranged along a circle having a diameter substantially the same as the inner diameter of the rotating polygonal mirror 1, and when the rotating polygonal mirror 1 is moved so that its rotation center passes along the straight line G, a surface contacting the inner peripheral surface of the mounting hole 2, respectively. And a plurality of columnar bodies 52 having
The claw portions 53 are formed on the respective columnar bodies 52 by bending the respective columnar bodies 52 at a height position corresponding to the depth of the mounting hole 2 toward the outside of the rotation center by a predetermined length. It has a structure.

A rotary shaft 6 is fitted and fixed to the rotation center of the rotary polygon mirror mounting base 50 from the bottom surface of the base plate 51, and the rotary polygon mirror is connected by a drive source (not shown) connected to the rotary shaft 6. It is configured so that the mounting base 50 can be rotated. Further, in the present invention, a shape memory alloy is used in manufacturing the rotary polygon mirror mounting base 50 having the above-described shape, and the rotary polygon mirror 1 and the rotary polygon mirror mounting base 50 are used.
The rotary polygon mirror 1 is fixed through the fixing steps shown in FIGS.

First, as shown in FIG. 2, the rotary polygon mirror mounting pedestal 50 molded with the above-described shape and requirements is provided with the columnar body 52 at the center of the rotary polygon mirror 1 in the mounting hole 2. With respect to the state of being inscribed, the state of being slightly expanded outward, that is, the diameter of the circle circumscribing each columnar body 52 is larger than the inner peripheral diameter of the mounting hole 2, By heating at a predetermined high temperature, so-called shape memory with the above shape is carried out. Next, after the rotary polygon mirror mounting base 50 is returned from the high temperature to the low temperature (for example, normal temperature), as shown in FIG. 3, the state opposite to the above, that is, the columnar bodies 52 are directed toward the center of rotation. The diameter of the circle that is converged and circumscribes the claw portion 53 is the mounting hole 2
The columnar body 52 is inserted into the mounting hole 2 until the upper surface of the pedestal plate 51 is in contact with the bottom surface of the rotary polygon mirror 1 with the shape. . Further, the columnar body 5 is formed in a form as shown in FIG.
By heating 2 at the same high temperature as when the shape memory is performed as described above, the shape of each columnar body 52 is restored to the state as shown in FIG. Here, the columnar body 5
The shape memorized by 2 is a shape in which the diameter of the circle circumscribing each columnar body 52 is larger than the inner diameter of the mounting hole 2 as shown in FIG. Therefore, in the process of recovering to this shape, each columnar body 52 is in contact with the inner peripheral surface of the mounting hole 2 without any interval, and the center of the rotary polygon mirror 1 is maintained at the rotation center of the rotary shaft 6 (on the straight line G). In addition, the claw portion 53 is in contact with the upper surface of the rotary polygon mirror 1 so as to cover the rotary polygon mirror 1 from above, and the rotary polygon mirror 1 is fixed to the pedestal plate 5.
It acts to hold it in between 1. After all, in this rotary polygon mirror 1, the rotary polygon mirror can be securely fixed only by heating without using a fixing member such as a fixing screw 7 and a fixing member 8 (see FIG. 5) or a fixing tool. This is effective not only to prevent damage but also to prevent deformation of the joint with the rotary shaft 6 due to improper stress applied when the fixing screw 7 is tightened. In the above example, only the mounting hole 2, the pedestal plate 51, and the columnar body 52 are all arranged in a circular shape.

[Effects of the Invention] As described above, according to the rotary polygon mirror mounting base of the present invention, the shape memory alloy is used as the forming material, and the shape is memorized in the state expanded from the mounting hole of the rotary polygon mirror on the high temperature side. The columnar body is reversely deformed on the low temperature side to be inserted into the mounting hole, and in the process of again recovering the shape of the columnar body on the high temperature side, the center of the rotary polygon mirror and the rotation axis are aligned with each other. Since the rotary polygon mirror is fixed in a state where there is no space between the mounting hole and the columnar body, the mutual difference in radius can be suppressed to be extremely small, and at the same time, it can contribute to simplification of assembly work and improvement in quality. It has an excellent effect.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an example of a rotary polygon mirror mounting base according to the present invention, and FIGS. 2 to 4 are built-in cross sections showing a fixing process of the rotary polygon mirror to the rotary polygon mirror mounting base of the present invention. FIG. 5, FIG. 5 and FIG. 6 are exploded structural views and an assembled sectional view showing an example of a conventional rotary polygon mirror mounting base, and FIG. 7 is a rotary polygon mirror fixed by the conventional rotary polygon mirror mounting base. It is a scanning optical path diagram. DESCRIPTION OF SYMBOLS 1 ... Rotating polygon mirror, 2 ... Mounting hole, 3 ... Flange part, 4 ... Shaft part, 5 ... Mounting base, 6 ... Rotating shaft, 7 ... Fixing screw, 8 ... Fixing member, 50 ... Rotating polygon mirror mounting base, 51 … Pedestal board, 5
2 ... Columnar body, 53 ... Claw

Claims (1)

[Claims] 1. A claw portion is formed by bending the tips of a plurality of columnar bodies toward the outside of the center of rotation at a height position corresponding to the depth of a mounting hole of a rotary polygonal mirror, and the columnar bodies. Is formed of a shape memory alloy that has a shape memory in a state of being expanded to the outside of the mounting hole, and after fitting each of the columnar bodies into the mounting hole in a state where the claw portion is housed in the mounting hole, A rotary polygon mirror mounting base, characterized in that the rotary polygon mirror is fixed by recovering its shape.