JPH11119142A - Deflecting scanner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a rotary polygon mirror from generating a positional deviation. SOLUTION: A bearing surface metal fitting 32 is attached to the upper end of a cylindrical rotary shaft 31 made of ceramics and a metallic rotary polygon mirror 33 is engaged with the fitting 32. A hole part 34 is formed on the center part of the mirror 33 and an approximately cylindrical part 35 of the fitting 32 is inserted into the hole part 34. Plural slits 36 are formed on the cylindrical part 35 in the axial direction, the cylindrical part 35 is formed as a tapered taper part 37 and a collar part 38 having a step part recessed to the inside is formed on the base part of the taper part 37. Further, the fitting 32 is also provided with a bearing surface part 39 for receiving the mirror 33.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a deflection scanning device used for a laser beam printer or the like.

[0002]

2. Description of the Related Art FIG. 3 is a diagram showing the entire configuration of a scanning optical system using a deflection scanning device. A laser unit 2 is mounted on an optical box 1 and a deflection optical path L emitted from the laser unit 2 is placed on the optical path L. A rotary polygon mirror 3 and a lens 4 and 5 serving as a scanning device are disposed inside the optical box 1, and a photoconductor 6 serving as a recording medium is disposed outside the optical box 1.

A laser beam emitted from a laser unit 2 is deflected and scanned by a rotating polygon mirror 3 supported and rotated by a bearing device, and passed through lenses 4 and 5 to form an optical box 1.
The light beam is projected as a spot light on the outer photosensitive member 6 and main scanning is performed.

A corona discharge device for uniformly charging the surface of the photoconductor 6 is provided around the photoconductor 6, and an electrostatic latent image formed on the surface of the photoconductor 6 is visualized as a toner image. And a transfer unit for transferring the toner image onto the recording paper, etc., and the recording information by the laser light generated from the laser unit 2 is printed on the recording paper or the like.

For example, in Japanese Unexamined Patent Publication No. 8-5951, the deflection scanning device has a motor housing 21 provided with a fixed shaft 22 made of ceramic as shown in FIG. A cylindrical rotary sleeve 23 made of ceramic is rotatably fitted on the fixed shaft 22, and a flange 24 made of a nonmagnetic metal material such as aluminum or brass is fitted on the rotary sleeve 23, for example, by shrink fitting. And so on. A drive magnet 25 is attached to the outer periphery of the flange 24 by means such as bonding. A motor board 26 provided with electric components is mounted on the upper surface of the motor housing 21.
A stator 27 opposed to the drive magnet 25 is disposed on the upper side to form a drive motor for rotating the rotary sleeve 23 and the like. I have.

[0006]

However, in the above-described conventional example, there is a slight gap between the hole of the rotary polygon mirror 28 and the rotary sleeve 23, and when the fixing is performed by the leaf spring 29, the gap is reduced by an impact due to the gap. The rotating polygon mirror 28 may be displaced, the balance of the rotating body may be easily lost, and vibration noise may increase.

Further, the flange 24 for fixing the rotary polygon mirror 28 is firmly pressed into the rotary sleeve 23. As a result, the hollow rotary sleeve 24 loses the tightening force of the press-fitting and its cylindricity may be degraded. Yes, this deviation in cylindricity also causes contact galling of the air bearing.

An object of the present invention is to solve the above-mentioned problems,
It is an object of the present invention to provide a deflection scanning device in which the position of a rotary polygon mirror is hardly shifted.

[0009]

According to the present invention, there is provided a deflection scanning apparatus according to the present invention, wherein a rotary polygon mirror is fixed to a substantially cylindrical portion of a seat bracket attached to a tip of a rotating shaft. The fixing is characterized in that the substantially cylindrical portion is elastically contracted in a radial direction and fitted into the hole of the rotary polygon mirror.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the embodiments shown in FIGS. FIG. 1 is a cross-sectional view of an embodiment, in which a seat metal fitting 32 is attached to the upper end of a cylindrical rotating shaft 31 made of ceramic which is rotated by a magnetic driving force of a surrounding electromagnetic coil 30 and the like. A rotating polygon mirror 33 made of metal is attached to the surface fitting 32. A hole 34 is formed at the center of the rotary polygon mirror 33, and a substantially cylindrical portion 35 of the seat fitting 32 is inserted into the hole 34. The substantially cylindrical portion 35 has a plurality of slits 36 in the axial direction.
And a tapered portion 37 having a tapered portion, and a base portion of the tapered portion 37 having a stepped portion recessed inward.
8 are provided. The seat bracket 32 is provided with a seat portion 39 for receiving the rotary polygon mirror 33.

As shown in FIG. 2, before the rotary polygon mirror 33 is mounted, the outer diameter of the seat bracket 32 is made slightly larger than the inner diameter of the hole 34 of the rotary polygon mirror 33. The portion having the large outer diameter, that is, the flange portion 38 is contracted and deformed by using a tool so that the outer diameter of the seat bracket 32 is slightly smaller than the diameter of the hole 34 of the rotary polygon mirror 33. The face fitting 32 is inserted into the hole 34.

In this case, the tapered portion 37 is substantially cylindrical portion 3
5 facilitates insertion and reduces the contact area to reduce friction. When the tool is removed, the shape of the flange portion 38 is restored by the elastic force, and the hole portion 34 of the rotary polygon mirror 33 is removed.
Will be tightly adhered to.

In this way, even if a shock or the like is received, the rotating polygon mirror 33 does not shift, and the balance of the rotating body is not lost, so that the vibration noise can be reduced.

Even if the rotary shaft 31 is firmly pressed into the seat bracket 32, the rotary shaft 31 is solid, so that it does not lose the tightening force of press-fitting and the roundness is not deviated. High reliability can be demonstrated without worrying about contact galling.

Further, since the rotating shaft 31 made of ceramic has a high hardness, the seating bracket 32 can be firmly fixed even with a small press-fit margin. Therefore, the tip of the rotating shaft 31 needs to have the minimum height, so that an expensive ceramic material can be saved and the effect of cost reduction can be obtained.

[0016]

As described above, the deflection scanning apparatus according to the present invention is fixed by inserting the elastic seating metal fitting into the hole of the rotary polygon mirror, so that the rotary polygon mirror is less likely to be displaced. In addition, vibration noise can be reduced without losing the balance of the rotating body.

If this deflection scanning device is used for a scanning optical system, high-speed and high-precision deflection scanning can be stably performed over a long period of time at low cost.

[Brief description of the drawings]

FIG. 1 is a sectional view of an embodiment.

FIG. 2 is an explanatory view at the time of assembly.

FIG. 3 is a perspective view of a conventional scanning optical system.

FIG. 4 is a sectional view of a conventional deflection scanning device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 31 Rotation axis 32 Seat fitting 33 Rotating polygon mirror 34 Hole 35 Substantially cylindrical part 36 Slit 37 Taper part 38 Flange part 39 Seat part

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Taku Fukita 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Mikio Nakasugi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon (72) Inventor Akihiro Fukutomi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (4)

[Claims] 1. A deflection scanning device in which a rotary polygon mirror is fixed to a substantially cylindrical portion of a seat metal fitting attached to a tip of a rotating shaft, wherein the fixing elastically shrinks the substantially cylindrical portion in a radial direction. The deflection scanning device is fitted in a hole of the rotary polygon mirror. 2. The deflection scanning device according to claim 1, wherein a plurality of slits are formed in an axial direction in a substantially cylindrical portion of the seat metal fitting. 3. The deflection scanning device according to claim 1, wherein a tapered portion is provided in a substantially cylindrical portion of the seat metal fitting, and a step is formed inwardly at a base of the tapered portion. 4. The deflection scanning device according to claim 1, wherein the rotation shaft is made of ceramic.