JPH0519198A - Scanning device - Google Patents

Abstract

PURPOSE:To use a thin scanning mirror which does not tilt, to miniaturize a device and to make the device highly accurate by providing a highly accurate attaching reference surface at the tip part of a rotary shaft and allowing the scanning mirror to abut on the reference surface. CONSTITUTION:A groove part 2a is provided on the top of the rotary shaft 2 in order to support the scanning mirror 1, and one side of the groove part 2a is set as the highly accurate attaching reference surface 2b on which the scanning mirror 1 is allowed to abut. The mirror surface 1a of the scanning mirror 1 is pressed and supported to the reference surface 2b by a pressing member 7 consisting of a set screw inserted into a hole 2c which is provided at the side part of the groove part 2a. Therefore, in the case of attaching the scanning mirror 1, the mirror 1 is accurately positioned without causing the mirror surface tilt only by fitting the mirror 1 in the groove part 2a of the rotary shaft 2 and fixing the mirror surface 1a by the pressing member 7 so that it may abut on the reference surface 2b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanning device such as a laser beam printer using a scanning mirror.

[0002]

2. Description of the Related Art Conventionally, two methods have been widely used for fixing a polygon mirror of a light beam scanning device. The first is to provide a reference plane on a plane perpendicular to the mirror surface of the polygon mirror, and a reference plane on a plane perpendicular to the rotation axis on the rotor surface of the motor so that the reference planes are aligned with each other and the center hole of the polygon mirror is aligned. The second method is to fix the rotary shaft by fitting it into the central hole of the polygon mirror.

In recent years, the former has become mainstream because of its ease of manufacture. For example, if the polygon mirror has about 6 surfaces and the circumscribed circle diameter is about 60 mm, a hole is provided at the center of the polygon mirror. It is possible. On the other hand, in a plate-shaped scanning mirror having a mirror surface on both sides or one side, it is desired that the mirror surface be as close as possible to the rotation axis, and the closer the mirror surface is to the rotation center, the smaller the amount of movement with respect to the scanning surface. Therefore, it is possible to reduce the size of the scanning mirror.

[0004]

However, in the conventional scanning mirror, since the rotary shaft is inserted and fixed in the central hole provided in the scanning mirror, the mirror surface and the central hole are separated from each other due to the limit of processing accuracy of the mirror surface. Proximity is difficult.

Actually, considering that the shaft diameter of the motor is about 4 mm at the minimum, in the case of the two-faced mirror scanning mirror, the mirror surface interval needs to be about 10 mm. For example, when the focal length of the scanning lens is 120 mm, the scanning length on the focal plane is about 22 mm.
If 0 mm is required, the effective length of the mirror surface will be 14 mm. In other words, there is a limit to the size of the scanning mirror provided with the central hole, and it is extremely difficult to make it smaller.

Further, the processing standard for the mirror surface processing of the scanning mirror is that the plane orthogonal to the mirror surface is used as the reference surface,
If dust is caught during processing or the accuracy of the processing machine is poor, the perpendicularity between the reference surface and the mirror surface may change, causing so-called mirror surface tilt, which may cause uneven scanning line pitch.

The object of the present invention is to solve the above problems,
An object of the present invention is to provide a scanning device that uses a plate-shaped scanning mirror and can be manufactured with high accuracy, easily and inexpensively.

[0008]

A scanning device according to the present invention for achieving the above object is driven by a motor in a scanning optical system in which light is deflected by a flat plate-shaped scanning mirror having at least one surface as a mirror surface. A groove is provided at the tip of the rotating shaft, and one surface of the groove is used as a mounting reference surface parallel to the core axis of the rotating shaft, and one surface of the scanning mirror is brought into contact with the mounting reference surface. Is.

[0009]

In the scanning device having the above-described structure, the mirror surface of the scanning mirror is mounted on the mounting reference surface formed parallel to the rotation axis of the motor, so that the mirror surface is supported parallel to the rotation axis and is prevented from tilting due to the mounting of the mirror surface. It never happens.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail based on the illustrated embodiments. FIG. 1 is a sectional view of the scanning device of the first embodiment, and FIG. 2 is a plan view. Reference numeral 1 denotes a scanning mirror made of metal or glass whose one surface 1a or both surfaces 1a and 1b are mirror-finished, and the scanning mirror 1 is fixed to the tip of a rotary shaft 2. Rotating shaft 2
Is rotatably fitted in the bearing sleeve 3, and a stator coil 4 and a circuit board 5 are arranged around the bearing sleeve 3. A rotor 6 made of a plastic magnet is fixed to the rotating shaft 2. A groove 2a is provided on the top of the rotary shaft 2 to support the scanning mirror 1,
One surface of the groove 2a serves as a highly accurate mounting reference surface 2b for contacting the scanning mirror 1, and a pressing member 7 formed of a set screw inserted into a hole 2c provided at the side of the groove 2a The mirror surface 1a of the scanning mirror 1 is pressed and supported by the mounting reference surface 2b. Further, a dynamic pressure generating groove 2d is formed in a portion of the rotary shaft 2 inside the bearing sleeve 3, and a slight gap is provided between the rotary shaft 2 and the bearing sleeve 3, and oil is filled in this gap to form an oil dynamic pressure fluid. It is used as a bearing.

The thickness of the scanning mirror 1 in this case is 1 mm, both sides 1a and 1b are cut into parallel planes, and the surface thereof is protectively coated. The groove 2a of the rotary shaft 2 has a width of 1.5 mm, and the mounting reference surface 2b for contacting the scanning mirror 1 is formed at a position which is moved by 0.5 mm in the radial direction from the center of rotation.

Therefore, when mounting the scanning mirror 1,
The scanning mirror 1 is simply fitted into the groove portion 2a of the rotary shaft 2, and the mirror surface 1
It is only necessary to fix a by the pressing member 7 so as to abut the mounting reference surface 2b, and the scanning mirror 1 can be positioned with high accuracy without mirror surface tilt.

FIG. 3 is a plan view of the second embodiment, in which a leaf spring-shaped pressing member 10 for pressing the scanning mirror 1 is bent at a bent portion 10a so as to surround a part of the outer side of the rotary shaft 2. Is provided, and a claw 10b for engaging with the rotary shaft 2 is further provided.

Thus, the bending portion 10a prevents the scanning mirror 1 from protruding from the rotary shaft 2 in the radial direction thereof, and the claw 10b prevents the scanning mirror 1 from coming out in the axial direction.

FIG. 4 is a sectional view of the third embodiment. The scanning mirror 1 is provided with a screw hole 1c at the bottom thereof, and the rotary shaft 2 is provided with a hole 2e reaching the groove 2a from the outside as an attachment reference surface 2b. The mounting reference surface 2b is formed by the screws 11 in a direction orthogonal to each other.
It is fixed by pulling the mirror surface 1a of the scanning mirror 1 to.

With such a configuration, similarly, the scanning mirror 1 is accurately positioned on the mounting reference surface 2b of the rotary shaft 2.

[0017]

As described above, in the scanning device according to the present invention, a highly accurate mounting reference surface is provided at the tip of the rotating shaft, and the scanning mirror is brought into contact with the mounting reference surface so that the thin scanning mirror does not fall. Can be used, which enables significant downsizing and high accuracy.

[Brief description of drawings]

FIG. 1 is a sectional view of a first embodiment.

FIG. 2 is a plan view.

FIG. 3 is a plan view of the second embodiment.

FIG. 4 is a sectional view of a third embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Scanning mirror 1a, 1b Mirror surface 1c Screw hole 2 Rotating shaft 2a Groove portion 2b Mounting reference surface 2c, 2e hole 2d Dynamic pressure generating groove 3 Bearing sleeve 7, 10 Pressing member 11 Screw

Claims (1)

Claim: What is claimed is: 1. In a scanning optical system in which light is deflected by a flat plate scanning mirror having at least one surface as a mirror surface, a groove portion is provided at a tip end portion of a rotation shaft driven by a motor, and the groove portion A scanning device, wherein one surface is a mounting reference surface parallel to a core axis of the rotating shaft, and one surface of the scanning mirror is in contact with the mounting reference surface.