JPH0815628A - Light deflector - Google Patents

Abstract

PURPOSE:To provide the small-sized, inexpensive stable rotation with less vibration. CONSTITUTION:A cap 29 formed by a metal member such as brass, etc., is attached to an upper end of a rotary sleeve 22 formed by ceramics by adhesion, and a ring 31 formed by the same member as the cap 29 is attached to an outer periphery of a ring-shaped permanent magnet 30 for thrust float attached to the lower end also by adhesion, etc., similarly. Then, when the rotation balance of a rotary body constituted of a rotary mirror 26 and the rotary sleeve 22 attaching its fixing member 24, etc., is adjusted, the rotary body is held by the cap 29 and the ring 31, and the injury onto the rotary sleeve 22 and the permanent magnet 30 is prevented, and the rotation balance is corrected precisely.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical deflector for use in an image recording apparatus using a laser beam or the like, for scanning a laser beam on a photosensitive member by rotating a rotating mirror. .

[0002]

2. Description of the Related Art As a conventional optical deflector, one shown in FIG. 5 is known. That is, a vertical fixed shaft 2 having a lower end fixed to the housing 1 is provided, and a rotary sleeve 3 is rotatably fitted to the fixed shaft 2. Housing 1
Is provided with a coil 4, a rotary sleeve 3 is provided with a drive permanent magnet 5 to form a drive motor, the rotary sleeve 3 is provided with a land portion 3a, and a rotary mirror 6 is attached thereto. .

The rotating mirror 6 includes a land portion 3a and a rotating sleeve 3.
It is sandwiched between the ring 7 and the ring 7 that is fitted to the land 7, and is fixed by the screw 8 that tightens the ring 7 toward the land portion 3a. On the upper surface of the ring 7, a groove 7a is formed concentrically with the ring 7 for attaching a weight when adjusting the balance of the rotating sleeve 3 to which these are attached. Another ring 9 with a groove 9a of similar purpose is mounted.

A groove 2 for generating a dynamic pressure is formed on the outer periphery of the fixed shaft 2.
a is formed, a shaft hole 10a for adjusting thrust pressure is provided at the center of the upper end of the rotary sleeve 3, and a thrust bearing 10 having a thrust receiving groove is attached to the bottom surface to form a hydrodynamic bearing. ing.

If the rotating body including the rotating sleeve 3 and the rotating mirror 6 is unbalanced, the rotating body rotates at a high speed, which causes a large vibration, which prevents stable rotation and causes a large noise. Therefore, a weight is attached to the grooves 7a and 9a to adjust the balance of the rotating body.

[0006]

However, in an optical deflecting device using such a hydrodynamic bearing, it is difficult to miniaturize it because dynamic pressure is generated and stable rotation with small vibration is generated. Since the diameter and length of the shaft are limited, the size of the device becomes large, and the cost for forming the dynamic pressure generating groove is high.

An object of the present invention is to solve the above problems,
An object of the present invention is to provide an optical deflector which is small in size and low in cost, has small vibration, and can obtain stable rotation.

[0008]

An optical deflecting device according to the present invention for achieving the above object is an optical deflecting device which deflects light by rotating a rotary mirror, and a fixed shaft made of a ceramic material. A rotary sleeve made of a ceramic material fitted to the fixed shaft and rotatably held, wherein a rotary mirror is attached to the rotary sleeve, and at least one of the upper and lower sides of the rotary mirror and the outer circumference of the rotary sleeve An annular metal member used for holding during balance adjustment is provided.

[0009]

In the optical deflecting device having the above-described structure, the metal member used for balancing the rotary sleeve having the rotary mirror is disposed on at least one of the upper and lower sides of the rotary sleeve.

[0010]

DETAILED 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 schematic configuration diagram of an optical deflector according to a first embodiment. A lower end of a vertical fixed shaft 21 made of a ceramic material is fixed to the motor housing 20, and a rotary sleeve 22 made of a ceramic material and closed at the upper end is rotatably fitted to the fixed shaft 21. There is. An air reservoir 23 is provided between the upper end of the fixed shaft 21 and the upper end of the rotating sleeve 22 to form an air damper, and the upper end of the rotating sleeve 22 has an air reservoir 23.
There is provided a small-diameter hole 22a that communicates with the outside.

A disk-shaped fixing member 24 is fixed to the outer periphery of the rotary sleeve 22 by shrink fitting or the like.
A drive permanent magnet 25 is attached along the outer peripheral surface of the fixing member 24, and a groove 24a concentric with the fixing member 24 is provided on the lower surface of the fixing member 24. A rotary mirror 26 is attached to the upper surface of the fixed member 24, and the rotary mirror 26 is pressed and fixed toward the fixed member 24 by a spring 27 attached to the upper portion of the rotary sleeve 22. A groove 28 concentric with 22 is provided.

Further, the cap 2 is formed of a metal member such as brass at the upper end of the rotary sleeve 22 and has a hole 29a at the center.
9 is attached by adhesion or the like, and the rotary sleeve 22
An annular permanent magnet 30 is attached to the lower end of the, and an annular ring 31 made of the same material as the cap 29 covers the outer peripheral surface of the permanent magnet 30 and a part of the outer peripheral surface of the rotary sleeve 22. Attached by gluing, etc.

On the other hand, in the motor housing 20, a motor substrate 32 and a drive permanent magnet 2 which constitute a motor drive circuit.
5 is attached to the coil 33 disposed at a position opposed to the fixed shaft 21. Further, in the motor housing 20 below the fixed shaft 21, an annular permanent magnet 34 repels the permanent magnet 30 at a position below the permanent magnet 30. It is fitted to fit.

When inspecting the rotational balance of a rotary body composed of members such as the rotary sleeve 22, the rotary mirror 26, the drive permanent magnet 25, etc., as shown in FIG. The cap 29 and the ring 31 are respectively placed and rotated for inspection, and vibrations caused by imbalance are detected by the two sensors 43 and 44. When the rotation is unbalanced, the weight W is attached to the grooves 24a and 28 to correct the balance.

As described above, when the rotational balance is inspected, the rotating body is held by the cap 29 and the ring 31, so that the drive permanent magnet 25 and the rotating sleeve 22 made of a ceramic material may be scratched or cracked. Therefore, the strength does not become weak. Therefore, the rotating body that rotates at a high speed when the device is used is not likely to be damaged by the centrifugal force.

The drive permanent magnet 25 fixed to the rotary sleeve 22 by an adhesive means is
It is difficult to install it while maintaining a high degree of coaxiality with the inner diameter of. Therefore, if the drive permanent magnet 25 is held to correct the balance of the rotating body, it is difficult to achieve accurate balance. Therefore, as described above, the cap 29 and the ring 31 are fitted and attached to the outer circumference concentric with the inner circumference of the rotary sleeve 22, or preferably, the outer diameters of the cap 29 and the ring 31 are processed based on the inner diameter of the rotary sleeve 22. As a result, the coaxial accuracy is improved and the balance can be corrected accurately.

In this way, the balanced rotating body is fitted with a small gap between the rotating sleeve 22 and the fixed shaft 21, so that it is completely non-contact with the air film in the radial direction. Since it is supported in a stable non-contact state by the repulsive force of the permanent magnets 30 and 34 and the air reservoir 23 also in the thrust direction, miniaturization is possible and stable rotation is obtained.

FIG. 3 shows a second embodiment. Instead of the fixing member 24 in the first embodiment, a fixing member 51 having an extension 51a along the rotary sleeve 22 is provided, and the cap 29 is omitted. There is. The fixing member 51 is a metal member such as brass attached to the rotary sleeve 22 by shrink fitting, and the spring 27 is attached to a recess provided in the extension portion 51a.

When inspecting the rotational balance of the rotating body,
The ring 31 and the extension 51a of the fixing member 51 are held by the rollers of the correction table.

By configuring as in the second embodiment, the same effect as in the first embodiment can be obtained, and in addition, the cap to be attached to the upper surface of the rotary sleeve 22 is unnecessary, and the assembling is simplified. At the same time, the rotating mirror 26 can be removed, and the manufacturing cost can be further reduced.

FIG. 4 shows a rotating body of the third embodiment, in which the groove 24a of the fixing member 24 in the first embodiment is omitted, and instead of the ring 31, a weight for adjusting the balance is provided. Ring 5 with groove 52a for mounting
2 are provided.

Normally, the rotating mirror 26,
The fixed member 24 and the drive permanent magnet 25 are attached to a relatively heavy one, and the center of gravity G is located at the substantially central portion of the rotating body. Therefore, when these weights are unbalanced or are not properly attached to the rotary sleeve 22, vibrations such as an arrow occur about the center of gravity G of the rotating portion as a center. The position for attaching the weight for correcting the distance becomes far from the center of gravity, and a small weight is sufficient for the correction.

In the above-described embodiments, the case where the rings for protecting the rotary sleeve 22 and the drive permanent magnet 25 are arranged vertically is described, but as the ceramic material, for example, high strength silicon nitride (Si ₃ N ₄ ) or the like is used. In the case of using, since the ceramic material itself has sufficient strength so as not to be damaged during rotation, it is possible to hold this ceramic portion and correct the balance. Therefore, the rotary sleeve 2 using such a ceramic material
In the case of 2, the same effect can be obtained by disposing the metal member only on the lower rings 31 and 46 that protect the permanent magnet 30 and the like that may be damaged and damaged.

[0024]

As described above, in the optical deflecting device according to the present invention, the fixed shaft and the rotating sleeve are made of ceramic material and are fitted to each other, and when the unbalance of the rotating body is corrected, Since a metal member such as a ring that protects the permanent magnets is provided, the rotating body can be balanced with high accuracy without damaging the rotating sleeve or the permanent magnets, which enables stable rotation with less vibration. Since the dynamic pressure generating groove is unnecessary, the size can be reduced.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a first embodiment.

FIG. 2 is a perspective view of balance correction of a rotating body.

FIG. 3 is a schematic configuration diagram of a second embodiment.

FIG. 4 is a schematic configuration diagram of a rotating body according to a third embodiment.

FIG. 5 is a schematic configuration diagram of a conventional example.

[Explanation of symbols]

 21 fixed shaft 22 rotating sleeve 24, 51 fixing member 24a, 28, 52a groove 26 rotating mirror 29 cap 30, 34 permanent magnet 31, 52 ring

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kenichi Tomita, 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor, Kazuo Togetsu 3-30-2 Shimomaruko, Ota-ku, Tokyo (72) Inventor Kimio Kono 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (4)

[Claims] 1. An optical deflecting device for deflecting light by rotating a rotary mirror, wherein a fixed shaft made of a ceramic material and a rotary sleeve made of a ceramic material fitted to the fixed shaft and rotatably held. A rotary mirror is attached to the rotary sleeve, and an annular metal member used for holding at the time of balance adjustment is disposed on at least one of the upper and lower sides of the rotary mirror and the outer circumference of the rotary sleeve. And a light deflection device. 2. The optical deflector according to claim 1, wherein a flange portion for mounting the rotating mirror is provided on one of the metal members. 3. The optical deflector according to claim 1, wherein a thrust levitation permanent magnet is arranged at a lower end of the rotary sleeve, and the metal member is attached around the permanent magnet. 4. The optical deflector according to claim 1, wherein a groove for fixing a weight is provided on at least one of the metal members.