JP3311231B2 - Light deflection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical deflecting device having a rotary polygon mirror for scanning a light beam such as a laser beam onto a photosensitive member, for example.

[0002]

2. Description of the Related Art In recent years, this type of scanning optical device has been required to rotate a rotary polygon mirror at high speed or with high accuracy. In particular, in a laser beam printer or the like, in order to obtain a high-precision light deflecting device, A non-contact rotating bearing is used.

FIG. 5 shows a light deflecting device of a laser beam printer using a non-contact bearing filed by the present applicant. That is, the rotary sleeve 2 is rotatably fitted around the fixed shaft 1, and these are formed of a ceramic material. A mirror receiving member 3 made of a metal material is attached to the outer periphery of the rotating sleeve 2 by shrink fitting or the like. A rotating polygon mirror 4 is fixed to the mirror receiving member 3 by a leaf spring 5, and a driving magnet 6 is provided. It is fixed by bonding or the like.

[0004] The fixed shaft 1 is fixed to a motor housing 7, and a motor board on which a stator 8 and electric components are mounted is disposed at a position facing the driving magnet 6 in the motor housing 7 to form a driving motor. I have. Further, a permanent magnet 10 is disposed below the rotating sleeve 2, while a permanent magnet 11 that is vertically opposed to the permanent magnet 10 is disposed on the fixed shaft 1.
11 repel each other and support the thrust load.

Here, the rotating sleeve 2 is driven by a drive motor.
Is rotated, an air film is formed between the fixed shaft 1 and the rotating sleeve 2, and the rotating sleeve 2 and the rotating polygon mirror 4 can be driven to rotate in a non-contact manner.

Further, in order to form an air pocket so that the rotating body does not move up and down when an external force is applied to the rotating body, a bearing cap may be attached to the upper end of the rotating sleeve 2 to provide an air damper effect. .

[0007]

However, in the above-mentioned prior art, a leaf spring 5 for fixing the rotary polygon mirror 4 is mounted on the mirror receiving member 3 mounted on the rotary sleeve 2 or on the rotary sleeve 2. Therefore, the total length of the rotary sleeve 2 becomes longer, the air receiving portion becomes longer than necessary, and it becomes difficult to reduce the size of the optical deflecting device.
Costs such as processing costs increase.

In order to improve the processing accuracy of the inner peripheral portion of the rotating sleeve 2, the mirror receiving member 3 is attached to the rotating sleeve 2
When the inner peripheral surface of the rotary sleeve 2 is machined after being attached to the inner surface of the rotary sleeve 2 by shrink fitting or the like, if the outer peripheral surfaces at both ends of the rotary sleeve 2 are not exposed, there is a disadvantage that highly accurate and efficient processing cannot be performed. .

An object of the present invention is to solve the above-mentioned problems,
In addition to minimizing the length of the air bearing by the necessary length,
An object of the present invention is to provide an optical deflecting device that makes an air bearing highly accurate and inexpensive.

[0010]

According to the present invention, there is provided a light deflecting device for deflecting a light beam emitted from a light beam generating means by an outer peripheral surface of a substantially annular rotating polygon mirror. A deflecting device, wherein the rotating polygon mirror and the driving magnet are fixed to a mirror receiving member attached to a rotating sleeve of an air bearing, a bearing cap is attached to an upper end of the rotating sleeve, and an outer diameter of the bearing cap is It is characterized in that it is smaller than the inner diameter of the rotating polygon mirror, and that the bearing cap is provided with fixing means for the rotating polygon mirror.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the embodiments shown in FIGS. 1 and 2 show a first embodiment. In FIG.
A fixed shaft 22 made of a ceramic material is fixed to the fixed shaft 2.
2 is rotatably fitted. Here, the ceramic material used for the fixed shaft 22 and the rotating sleeve 23 has a low possibility of galling or the like even when the ceramic material comes into contact with dust or the like or due to vibration during high-speed rotation. Rotating sleeve 2
A mirror receiving member 24 made of a metal material such as brass or aluminum is fixed to the outer periphery of the base 3 by shrink fitting.
A driving magnet 25 is fixed to the outer periphery of the mirror receiving member 24 by bonding, and the substrate 2 fixed to the housing 21.
The drive motor is configured by disposing the stator 27 on the motor 6 so as to face the drive magnet 25.

At the lower end of the rotating sleeve 23, a magnetic pole of the same type as the first permanent magnet 28 disposed on the fixed shaft 22 or the housing 21 is fixed. I have. In the vicinity of the rotating sleeve 23 of the housing 21, the second permanent magnet 29 fixed to the lower end of the rotating sleeve 23 is pressed in a direction of pressing the fixed shaft 22 or the first permanent magnet 28 provided on the housing 21. The third permanent magnet 30 is arranged so that a repulsive force acts, and the rotating sleeve 23 and the components attached thereto are supported in the thrust direction.

Here, the mirror receiving member 24 is provided with a protruding portion 24a at the upper side, so as to fit with the inner diameter portion 31a of the substantially annular rotating polygon mirror 31 placed on the mirror receiving member 24. The rotating polygon mirror 31 is fixed by a spring 32. Further, the mirror receiving member 24 and the rotating sleeve 23
A gap 33 is provided between the rotating polygon mirror 31 and the mirror receiving member 24 even when there is a temperature change.
Similarly, the protruding portion 24a, which is the fitting portion, expands and contracts, and the rotating polygon mirror 31 is less likely to be displaced.

Here, a bag-like bearing cap 35 is provided at the upper end of the rotating sleeve 23. The bearing cap 35 is attached to the outer peripheral portion of the rotating sleeve 23, and the attachment is fixed with an adhesive or the like, and an air reservoir 36 is formed. A groove 37 is provided in the bearing cap 35, and a leaf spring 32 for fixing the rotary polygon mirror 31 is fixed directly or via a C-ring or the like.

Here, the inner diameter D of the bearing cap 35 is smaller than the inner diameter d of the rotating polygon mirror 31 (D <d), so that the rotating polygon mirror 31 is attached after the bearing cap 35 is assembled.

A laser beam L rotated by a drive motor and emitted from a laser unit 42 disposed in an optical box 41 as shown in FIG. 2 is deflected by the rotating polygon mirror 31 and condensed by lenses 43 and 44. Photoconductor 4
5 is scanned.

With such a configuration, since the fixing means such as the leaf spring 32 for fixing the rotary polygon mirror 31 is attached to the bearing cap 35, the height of the rotary sleeve 23 is reduced. 31, it is possible to reduce the length of the rotary sleeve 23 to the minimum length as an air bearing, and it is possible to reduce the size of the optical deflecting device.

The mirror receiving member 2 is
Since the outer peripheral surfaces at both ends of the rotary sleeve 23 are exposed after the shrink-fitting of the bearing 4, despite the shortened bearing portion, the outer peripheral surface is supported and the inner peripheral surface of the rotary sleeve 23 is mass-produced. It is possible to perform processing such as centerless grinding, which is suitable for the above, to remove deformation of the inner peripheral surface due to shrink fitting of the mirror receiving member 24, and to obtain the rotating sleeve 23 with high precision. Therefore, since a relatively expensive and difficult-to-machine material such as ceramic can be used to shorten a high-precision part, it is possible to reduce the cost.

FIG. 3 shows a second embodiment, in which the same members having the same functions as those in FIGS. 1 and 2 are denoted by the same reference numerals and description thereof is omitted. In FIG. 3, a small hole 42 for venting air is provided in a bearing cap 41 provided at the upper end of the rotating sleeve 23.
A sealing member 43 is fixed to the tip of the sealing member 43 by bonding or the like.

With such a configuration, a member to be attached to the rotating sleeve 23, for example, the mirror receiving member 2
4. Attach all the rotating polygon mirrors 31 and, after inserting them into the fixed shaft 1, finally fix the sealing member 43 by bonding,
By forming, air bleeding at the time of insertion becomes easy, and the same effect as in the first embodiment can be obtained.

FIG. 4 shows a third embodiment, in which a bearing cap 44 provided at the upper end of the rotary sleeve 23 has a circumferential groove 44a at a portion where the upper end surface of the rotary sleeve 23 abuts.
Is provided.

By providing the groove 44a, when the bearing cap 44 is bonded to the rotating sleeve 23, it is possible to prevent an extra adhesive from entering the inside of the bearing. Therefore, it is possible to reduce the possibility that the failure of the bearing due to the invasion of the adhesive occurs.

Further, an adhesive can be applied to the outer peripheral portion of the groove 44a on the end face, and the adhesive strength in the axial direction can be ensured. In the above description, the groove 44 is formed in the bearing cap 44.
Although the case where a is provided has been described as an example, the same effect can be obtained by providing a groove on the upper end surface of the rotating sleeve 23.

Further, in the second and third embodiments, the small holes 42 of the bearing caps 41 and 44 are fixed with the sealing member 43 by bonding, but the leaf springs are directly connected to the small holes using screws. It is also possible to fix to. In addition, although the groove is provided and fixed in the fixing portion of the spring, the spring may be fixed with a screw or the like other than the groove.

[0025]

As described above, the optical deflecting device according to the present invention has the bearing cap attached to the rotating sleeve, the outer diameter of the bearing cap is made smaller than the inner diameter of the rotary polygon mirror, and the bearing cap is mounted on the bearing cap. By mounting the rotating polygon mirror fixing means, it is not necessary to make the length of the air bearing unnecessarily long, and the size can be reduced. In addition, since the outer peripheral surfaces of both ends of the rotating sleeve are exposed, that is, the inner peripheral surface of the rotating sleeve can be processed by receiving the outer peripheral surface, even if the rotating sleeve is shortened, highly accurate and efficient processing becomes possible. Cost can be reduced.

[Brief description of the drawings]

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

FIG. 2 is a plan view of a scanning optical system.

FIG. 3 is a cross-sectional view of a second embodiment.

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

FIG. 5 is a cross-sectional view of a conventional light deflecting device.

[Explanation of symbols]

 Reference Signs 22 fixed shaft 23 rotating sleeve 31 rotating polygon mirror 24 mirror receiving member 35, 41, 44 bearing cap

Claims (4)

(57) [Claims] 1. An optical deflector for deflecting a light beam emitted from a light beam generating means by an outer peripheral surface of a substantially annular rotating polygon mirror, wherein said rotating polygon mirror and a driving magnet are rotated by a rotating sleeve of an air bearing. A bearing cap is attached to the upper end of the rotating sleeve, and an outer diameter of the bearing cap is smaller than an inner diameter of the rotating polygon mirror, and the bearing cap is mounted on the bearing cap. An optical deflecting device comprising fixing means for a mirror. 2. The light deflecting device according to claim 1, wherein the bearing cap is fixed to an outer peripheral portion of the rotating sleeve by bonding. 3. The light deflecting device according to claim 1, wherein a small hole is provided in the bearing cap, and the small hole is sealed with a sealing member. 4. The optical deflecting device according to claim 1, wherein a groove is provided on one of surfaces on which the bearing cap and the upper end of the rotating sleeve abut.