JPH03172819A - Structure for mounting polygon mirror - Google Patents

Abstract

PURPOSE:To eliminate or decrease the deformation of mirror surfaces generated from thermal expansion and centrifugal force at the time of operation of a high-speed scanner by disposing an elastic member consisting of a rubber basis between the shaft part of a revolving shaft and the central hole part or upper surface of a polygon mirror. CONSTITUTION:The elastic member 5 consisting of the rubber basis having a high coefft. of friction is disposed as the stopper of a rotating direction between the inner peripheral surface of the central hole 1d of the polygon mirror 1 and the outer peripheral surface of the revolving shaft 2a positioned in the central hole 1d of the polygon mirror 1 by fitting the member to the revolving shaft 2a. The clamping force of a mounting screw 4 is sufficient with the force to press the reference plane 1b of the polygon mirror 1 closely to the flange part 2A of the revolving shaft and the clamping force on the reference plane 1b is decreased if the structure is formed in such a manner. The distortion of the mirror surfaces 1c by the increased face pressure of the reference plane 1b arising from the temp. rise and centrifugal force at the time of operation of the high-speed scanner is prevented by the decreased clamping force on the reference plane 1b of the polygon mirror 1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a mounting structure for a polygon mirror, which is a polygon mirror used in laser printers and the like.

[Conventional technology]

In a high-speed scanner device, there are 12 polygon mirrors,
Since the polygon mirror rotates at a high speed exceeding OOOr p m, it generates wind noise, and as a measure to reduce this noise, a method is generally adopted in which a portion of the polygon mirror is surrounded by a sealed housing.

The inside of the sealed housing that houses the polygon mirror experiences a temperature rise of 40 to 50 degrees relative to room temperature. Therefore, heat radiation fins are provided on the outer surface of the housing, and forced air cooling fans are installed to reduce the temperature rise. is being prevented.

However, in reality, a temperature rise of 10 to 20 degrees above room temperature cannot be avoided, and this heat causes deformation of the mirror surface of the polygon mirror.

That is, in the conventional polygon mirror mounting structure shown in Part 4, the polygon mirror 1 made of aluminum is placed on the flange portion 2A of the rotating shaft 2 made of rope, and the upper surface of the polygon mirror 1 is A retaining ring 3 is provided, and the mounting screw 4 made of steel is tightened through the hole 1a from the upper surface of the retaining ring 3 to the polygon mirror 1 by adjusting the force so that the reference surface 1b of the polygon mirror 1 is It is fixed so as to abut on the flange portion 2A with a predetermined surface pressure.

If the above-mentioned temperature rise occurs in this state, the linear expansion coefficient of the polygon mirror 1 made of aluminum is larger than that of the flange portion 2A of the rotating shaft and the mounting screw 4 made of steel, and the polygon mirror 1 is made of aluminum. In the thickness direction of the mirror, the polygon mirror 1 becomes tighter and the clamped state becomes stronger. Therefore, the surface pressure of the reference surface 1b of the polygon mirror 1 increases, and the mirror surface IC of the polygon mirror 1 is deformed.

In addition to the deformation of the mirror surface due to this thermal expansion, the mirror surface also undergoes deformation due to centrifugal force. It has been confirmed through experiments that the mirror surface deforms due to this centrifugal force in the fixing means shown in Fig. 4, when the frictional drag on the reference surface is large, the mirror surface becomes concave, and when the frictional drag is small, it becomes convex. ing.

[Problem to be solved by the invention]

As described above, the present invention is designed to prevent thermal expansion during operation of a high-speed scanner.
It is an object of the present invention to provide a polygon mirror mounting structure that can eliminate or reduce deformation of a mirror surface caused by centrifugal force.

[Means to solve the problem]

In order to achieve the above-mentioned object, the present invention aims to reduce the surface pressure between the reference surface of the polygon mirror and the flange of the rotation shaft, and to reduce the surface pressure between the center hole or upper surface of the polygon mirror and the shaft of the rotation shaft. It is characterized in that a rubber-based elastic member is arranged in between.

[For production]

With the configuration of the present invention, even if the surface pressure between the reference surface of the polygon mirror and the flange of the rotating shaft is reduced, the rubber-based elasticity between the center hole or top surface of the polygon mirror and the shaft of the rotating shaft can be reduced. Due to the arrangement of the members, even if the temperature rises, the surface pressure on the reference surface of the polygon mirror does not increase, and the mirror surface of the polygon mirror does not become deformed.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

Conventionally, as shown in FIG. 4, a polygon mirror 1 is fastened to a flange portion 2A of a rotating shaft 2 by the tightening torque of a mounting screw 4. This tightening torque, so-called clamping force, is
It is subject to the following restrictions.

That is, the upper limit of the clamping force is such that the surface pressure generated on the reference surface 1b of the polygon mirror does not deteriorate the flatness of the mirror surface IC, and the lower limit of the clamping force is the surface pressure generated on the reference surface ib of the polygon mirror. The clamping force is such that no slippage occurs between the reference surface 1b of the polygon mirror and the flange portion 2A of the rotating shaft. Generally, the surface pressure generated on the reference surface 1b of the polygon mirror is 50 gf/mm.
A clamping force in the range of "~100 gf/mm" is adopted.

The present invention deals with an increase in surface pressure applied to the reference surface 1b of the polygon mirror (deformation of the mirror surface due to thermal expansion) due to thermal expansion of the polygon mirror 1 due to temperature rise, and a reduction in the reference surface 1b of the polygon mirror due to centrifugal force. Size of frictional drag (surface pressure 5
The range from 0gf/mm” to 100gf/■C is a region where the frictional drag is large, and the mirror surface deforms due to centrifugal force)
In order to eliminate or reduce this, a means is provided which lowers the lower limit of the clamping force and reduces the surface pressure generated on the reference surface 1b of the polygon mirror.

In the embodiment shown in FIG. 1, in order to reduce the clamping force of the mounting screw 4, the rotation shaft 2a is located between the inner peripheral surface of the center hole 1d of the polygon mirror 1 and the center hole 1d of the polygon mirror 1.
A rubber-based elastic member 5 having a high coefficient of friction is disposed between the outer circumferential surface of the rotary shaft 2a and the rotary shaft 2a to prevent slippage in the rotational direction.

The clamping force of the mounting screw 4 is sufficient to press the reference surface 1b of the polygon mirror 1 onto the flange portion 2A of the rotating shaft without any gap, and therefore, the lower limit of the clamping force can be lowered than in the past. can.

Furthermore, in this embodiment, the mounting screw 4 is made of the same aluminum as the polygon mirror, and its displacement due to thermal expansion is made equal to that of the polygon mirror.

By reducing the clamping force on the reference surface 1b of the polygon mirror 1, adhesive is attached to the threaded hole 2b of the flange 2A at the end of the mounting screw 4 to prevent the mounting screw 4 from loosening during scanner operation. Agent 6 is filled.

Therefore, the rubber-based elastic member 5 with a high coefficient of friction is attached to the rotating shaft 2.
By disposing it between A and the center hole 1d of the polygon mirror, the clamping force on the reference surface 1b of the polygon mirror 1 can be reduced, and the reference surface 1 can be
The increase in the surface pressure b does not cause distortion of the mirror surface.

FIGS. 2 and 3 show another embodiment of the present invention having a similar purpose and reducing the number of parts.

In the second embodiment shown in FIG. 2, the reference surface 1 of the polygon mirror is
b is the clamping force (surface pressure) that contacts the flange portion 2A, and instead of using the mounting screw in FIG. A spring 8 is arranged. In this configuration,
Compared to the case where mounting screws are used, it is easier to lower the surface pressure on the reference surface of the polygon mirror.

In addition, in the third embodiment shown in FIG. 3, the clamping force on the reference surface 1b by the mounting screw 4 in FIG. 1 is reduced.
Instead of using the rubber-based elastic member 5, the mounting screws that generate surface pressure on the reference surface 1b are unnecessary, and the polygon mirror l
A rubber-based elastic member 9 is disposed between the upper surface of the rotary shaft 2 and a retaining ring 7 that is secured to the rotary shaft 2 so as to come into contact with the rotary shaft 2.

This rubber-based elastic member 9 is tightly fitted to the rotating shaft 2, and this tightening uses force to restrict slippage of the polygon mirror in the rotating direction.

In the embodiment shown in FIG. 3, a single rubber-based elastic member 9 prevents the polygon mirror 1 from slipping in the rotational direction and holds it down in the thrust direction.

In the above configuration of the present invention, the surface pressure generated on the reference surface of the polygon mirror is set to 50 gf/m as an initial value at the time of clamping.
By setting it to m2 or less, even if the polygon mirror thermally expands and the surface pressure increases, the mirror surface will not be distorted.

In the first embodiment using mounting screws, the increase in surface pressure can be suppressed by setting the surface pressure low as described above and using a material for the mounting screws that has a coefficient of thermal expansion equal to that of the polygon mirror. This can prevent the occurrence of distortion on the mirror surface.

In addition, in the configuration of the present invention, even with respect to deformation due to centrifugal force, the surface pressure generated on the reference surface of the polygon mirror can be set low, so that deformation of the polygon mirror due to centrifugal force can be minimized.

〔effect〕

According to the configuration of the present invention, since the rubber-based elastic member is disposed between the rotating shaft portion and the polygon mirror, the surface pressure between the reference surface of the polygon mirror and the flange portion of the rotating shaft can be reduced, and the surface pressure caused by temperature rise can be reduced. It is possible to prevent the deformation of the mirror surface due to the increase in the amount of polygon mirror, and also to minimize the deformation of the mirror surface caused by the frictional force acting on the reference surface of the polygon mirror due to centrifugal force.

[Brief explanation of the drawing]

Fig. 1 is a schematic sectional view showing a first embodiment of the present invention, Fig. 2 is a schematic sectional view showing a second embodiment of the invention, and Fig. 3 is a schematic sectional view showing a third embodiment of the invention. , FIG. 4 is a schematic sectional view showing a conventional configuration. 1... Polygon mirror 1b... Reference surface, 1c...
・Mirror surface, ld...center hole, 2...rotation axis, 2A
...Flange part, 2a...Rubber elastic member is attached to rotating shaft part, 3...Pressure ring, 4...Mounting screw, 5.
... Rubber-based elastic member, 7... Retaining ring, 8... Presser spring, 9... Rubber-based elastic member. Figure 4

Claims (1)

[Claims] In order to reduce the surface pressure between the reference surface of the polygon mirror and the flange of the rotating shaft, a rubber-based elastic member is placed between the center hole or top surface of the polygon mirror and the shaft of the rotating shaft. Mounting structure of polygon mirror.