JPH05127116A - Deflection device - Google Patents

Abstract

PURPOSE:To provide the deflection device which can reduce the frictional resistance between surrounding air and 2nd border parts, not to mention the resistance between the air and 1st border parts. CONSTITUTION:A plate type polygon main body 1 which rotates on its axis is provided and plural reflecting mirrors 4 which reflect light are arranged adjacently in the rotating direction to constitute a polygon mirror 58; and the 1st border parts between the reflecting mirrors 4 are formed into curved surfaces. Thin plates 3 (disk) which reduce the frictional resistance between the 2nd border parts between the reflecting mirrors 4 and the top and reverse surfaces of the polygon mirror 58 and the surrounding air when the polygon mirror 58 rotates are provided on the top and reverse surfaces of the polygon mirror 58 of the deflection device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a deflecting device used for a laser beam reflecting mechanism in a copying machine, a printer or the like.

[0002]

2. Description of the Related Art FIG. 5 shows a conventional deflecting device of this type. A plurality of reflecting surfaces 10 are provided on the outer periphery of the plate-shaped polygon mirror 100.
1 is arranged along the rotation direction A. Also, the reflective surface 1
The second boundary portion (ridge line) 102 between 01 is a curved surface such as a convex spherical surface or a convex cylindrical surface.

The polygon mirror 100 rotates in the direction of arrow A about an axis (not shown), and reflects the laser light B on the reflecting surface 101 to deflect it.

When the polygon mirror 100 rotates at a high speed, the frictional resistance between the boundary portion 102 and the gas is large, and the flow of gas around the polygon mirror 100 is disturbed. As a result, noise due to wind noise and frictional heat heat the polygonal mirror 100 to cause surface distortion of the reflecting surface 101, which reduces the deflecting function. Unless the driving force for rotating the polygonal mirror 100 is increased. However, there is a problem that power consumption increases.

However, as described above, the first boundary portion 102
If it is curved, the frictional resistance can be reduced to some extent and the above problems can be suppressed.

[0006]

However, in the above-mentioned conventional example, friction resistance occurs between the second boundary 104 between the reflecting surface 101 and the back surface 103 of the polygonal mirror 100 and the surrounding gas, and therefore the same as described above. The problem of remains.

The present invention is for solving the above-mentioned problems, and it is possible to reduce not only the friction resistance between the surrounding gas and the first boundary portion but also the friction resistance between the gas and the second boundary portion. Is intended to provide.

[0008]

In order to achieve the above object, the present invention provides a plate-shaped rotating body that rotates about an axis, and a plurality of reflecting surfaces that reflect light on the outer periphery of the rotating body. In a deflecting device in which a polygonal mirror is arranged adjacently along the rotation direction, and the first boundary portion of the plurality of reflecting surfaces is a curved surface, the reflecting surface and at least one of the front surface and the back surface of the polygonal mirror. A friction reducing means for reducing the frictional resistance between the second boundary portion and the surrounding gas when the polygon mirror is rotated is provided near the second boundary portion.

The friction reducing means is a disc provided on at least one of the front surface and the back surface of the polygon mirror.
The outer diameter of the disc was set larger than the circumscribed circle of the polygon mirror.

Further, the boundary between the disc and the reflecting surface is curved.

[0011]

According to the operation of the present invention based on the above structure, the polygon mirror rotates about the axis, and the plurality of reflecting surfaces reflect and deflect the light. During the rotation of the polygon mirror, the frictional resistance between the first boundary and the gas is reduced by the curved surface. On the other hand, the frictional resistance between the second boundary portion and the gas is reduced by the friction reducing means.

The disk rotates integrally with the polygon mirror.
Since the outer diameter of the disk is larger than the circumscribed circle of the polygonal mirror, the outer circumference of the disk substantially contacts the gas. Here, since the shape is a disk, the locus during rotation is always the same, and the frictional resistance with the gas is small.

Further, the frictional resistance at the boundary between the disc and the reflecting surface is further reduced.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an explanation will be given based on an embodiment in which the invention is applied to a copying machine. The copying machine 50 shown in FIG. 2B has a hollow printer section 51 and a scanner section 52 mounted on the printer section 51. The printer unit 51 is equipped with a cassette 30 containing recording paper and has a transfer drum 27. A first transport means 53 is provided between the cassette 30 and the transfer drum 27.

The photosensitive drum 2 is provided near the transfer drum 27.
8. A developing drum 54 is provided. Also, the cassette 30
A fixing device 31 is provided above the image forming device, and a second conveying unit 55 is provided between the fixing device 31 and the transfer drum 27.

Further, above the photosensitive drum 28, a polygon scanner motor 26 for rotatably driving a polygon mirror described later,
A mirror 56 and the like are provided.

On the other hand, in the scanner section 52, the light source 5
7. An optical system equipped with CCD 25 and the like is housed. C
The CD 25 and a semiconductor laser described later are connected by a cable.

In the above structure, a document (not shown) is illuminated by the light source 57, and the reflected light is read by the CCD 25. A semiconductor laser emits light in response to a signal read by the CCD 25, and the laser light D is irradiated onto the photosensitive drum 28 via the mirror 56 to form a latent image. This latent image is visualized with toner by the developing device 29 of the developing drum 54.

On the other hand, in response to the above operation, the recording paper in the cassette 30 is conveyed by the first conveying means 53 and adsorbed to the transfer drum 27. Then, the image on the photosensitive drum 28 is transferred onto the recording paper, the recording paper is sent to the fixing device 31 by the second conveying means, the image is fixed by heating and pressurizing, and the recording paper is discharged to the outside of the printer section 51. ..

By the way, the polygon scanner motor 2
A polygon mirror (polyhedral mirror) 58 shown in FIG. 2 (A) is provided above 6. The polygon mirror 58 is rotationally driven by the polygon scanner motor 26 in the arrow direction. The polygon mirror 58 is housed in a translucent case 59, and the semiconductor laser 24 and the collimator lens 23 are provided outside the case 59. Inside the case 59 and between the semiconductor laser 24 and the polygon mirror 58,
A cylindrical lens 22 is provided.

An imaging lens 21 is provided in the case 59.

FIGS. 1A and 1B are a plan sectional view and a side view of the polygon mirror 58. Polygon mirror 58
A plurality of (eight) reflecting mirrors 4 as reflecting surfaces are equally arranged adjacent to each other on the outer periphery of a polygonal body 1 as a plate-like rotating body along the rotation direction. The polygon main body 1 is made of aluminum that is less likely to thermally expand, and the boundary between the reflection mirrors 4 forms a convex curved surface 2 along the thickness direction of the polygon main body 1.

The reflection mirror 4 and the polygon body 1
A disk-shaped thin plate (friction reducing means) 3 is attached to at least one of the front and back surfaces, that is, in the vicinity of the boundary with both upper and lower surfaces in FIG. 1B, that is, the upper and lower surfaces. The outer diameter of this thin plate 3 is the circumscribed circle of the polygon body 1, that is, all the convex curved surfaces 2
It is set larger than the circle formed by connecting. The thickness of the thin plate 4 is about 2 mm in this embodiment, and the material thereof is aluminum, which is the same as that of the polygon body 1.

The laser light D emitted from the semiconductor laser 24 is diffused and radiated, but is converted into a cylindrical parallel beam by the collimator lens 23, and then the cylindrical lens 2 is used.
It can be converted into a flat belt-shaped parallel beam by 2.

In this embodiment, the polygon body 1 is 18000.
Rotating at rpm, the parallel beam is reflected by the reflecting mirror 4 and guided to the photosensitive drum 28 as described above.

During the rotation of the polygon body 1, the frictional resistance between the boundary between the reflection mirrors 4 and the surrounding gas is reduced by the convex curved surface 2.

The thin plate 4 rotates integrally with the polygon body 1. Since the outer diameter of the thin plate 4 is larger than the circumscribing circle of the polygon body 1, the outer periphery of the thin plate 4 substantially contacts the gas. Here, since the shape is a disk, the locus during rotation is always the same, and the frictional resistance with the gas is small.

As a result, no noise due to wind noise is generated, the reflection mirror 4 is not distorted by frictional heat, and accurate deflection characteristics can always be maintained. The driving force of the polygon scanner motor 26 for rotating the polygon mirror 58 is small. The effect is that power consumption can be suppressed.

FIGS. 3A and 3B show a second embodiment. The outer peripheral surface of the thin plate 3 of (A) is an R curved surface 5, and (B) is an example of a C curved surface 6. With this structure, the frictional resistance between the thin plate 3 and the gas can be further reduced. Other configurations, operations, and effects are similar to those of the first embodiment.

FIGS. 4A and 4B show a third embodiment. (A) is a reflection mirror 4 and a thin plate 3 of the polygon body 1.
A concave curved surface 7 is formed at the boundary with the reflection mirror 4, that is, at the upper and lower ends of the reflection mirror 4.
It is an example of applying. Further, (B) is an example in which the upper and lower ends of the reflection mirror 4 are provided with a C surface 8. Even in this case, the concave curved surface 7 and the C surface 8 can reduce the frictional resistance with the gas. The other configurations, operations and effects are similar to those of the first embodiment.

[0031]

Since the present invention is constructed as described above, not only the frictional resistance between the first boundary portion and the gas at the time of rotation of the polygon mirror but also the frictional resistance between the second boundary portion and the gas can be obtained. It can be reduced.

As a result, no noise due to wind noise is generated, the reflecting surface is not distorted by frictional heat, accurate deflection characteristics can be maintained at all times, the driving force of the driving source for rotating the polygon mirror is small, and the consumption is low. The effect of suppressing the current is further improved.

[Brief description of drawings]

FIG. 1 shows a polygon mirror according to a first embodiment of the present invention,
(A) is a cross-sectional plan view and (B) is a side view.

2A and 2B show a copying machine to which the present invention is applied, FIG. 2A is a plan view of a peripheral surface of a polygonal mirror, and FIG.

3A and 3B are side views of a polygon mirror according to a second embodiment of the present invention.

4A and 4B are side views of a polygon mirror according to a third embodiment of the present invention.

FIG. 5 is a perspective view of a conventional example.

[Explanation of symbols]

 1 Polygon main body (rotating body) 2 Convex curved surface (first boundary portion) 3 Thin plate (disk, friction reducing means) 4 Reflecting mirror (reflecting surface) D Laser light

Claims (3)

[Claims] 1. A polygonal mirror is provided in which a plate-shaped rotating body that rotates about an axis is provided, and a plurality of reflecting surfaces that reflect light are arranged adjacent to each other on the outer periphery of the rotating body along the rotation direction. Then
In a deflecting device having a curved first boundary portion between the plurality of reflecting surfaces, in the vicinity of a second boundary portion between the reflecting surface and at least one of the front surface and the back surface of the polygon mirror, A deflection device comprising friction reducing means for reducing frictional resistance between the second boundary portion and surrounding gas. 2. The friction reducing means is a disk provided on at least one of a front surface and a back surface of the polygon mirror, and an outer diameter of the disk is set to be larger than a circumscribed circle of the polygon mirror. Deflection device as described. 3. The deflecting device according to claim 2, wherein a boundary portion between the circular plate and the reflecting surface is curved.