JPH06289311A - Light deflector - Google Patents

Abstract

PURPOSE:To reduce wind whistle caused by air flowing out from the cover of a rotary polygon mirror. CONSTITUTION:The rotary polygon mirror 1 is covered with the almost cylindrical cover 2 and a window 3 where a laser light beam is passed is provided on the cylindrical wall 2a of the cover 2. The wall 2a is provided with a soundproof hood 4 surrounding the circumference of the window 3. Since the hood J4 projects outside from the wall 2a of the cover 2 in a diameter direction, the air flowing out from the window 3 is decelerated while it is passed through the hood 4. As the result, the wind whistle of the air flowing out from the cover 2 can be reduced.

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 deflecting and scanning a laser beam or the like at a high speed in a laser printer or the like.

[0002]

2. Description of the Related Art Optical deflectors for laser printers, laser facsimiles and the like have been particularly accelerated in recent years, and rotary polygon mirrors used for these deflectors rotate at high speeds of 10,000 or more revolutions per minute. When the rotary polygon mirror is rotated at such a high speed, the wind noise during rotation is increased and a large noise is generated. Therefore, the periphery of the rotary polygon mirror is covered with a substantially cylindrical cover.

FIG. 9 illustrates a general optical deflector, in which a laser beam L generated from a laser oscillator 110 is used.
After being condensed into a predetermined beam shape by the cylindrical lens 105, it is deflected and scanned by the rotary polygon mirror 101, and an image is formed on the photosensitive drum 107 via the imaging lens system 106. A part of the laser light reflected by the rotating polygon mirror 101 is reflected by the reflecting mirror 108 to the optical fiber 10.
9 and is converted into a scanning start signal.

FIG. 8 shows the rotary polygon mirror 101 and its drive unit. The drive unit of the rotary polygon mirror 101 is a rotary shaft 111.
And the rotor magnet 112 integrally connected to the
The rotary polygon mirror 1 includes a stator coil 114 that is integral with a bearing device 113 that supports the rotary shaft 111, and a circuit board 115 that supplies a drive current to the stator coil 114.
01 is a corrugated washer 116a and a flat washer 116b
A pressing mechanism 116 including a stopper ring 116c presses the flange member 111a, which is integrated with the rotating shaft 111, and thereby is integrated with the rotating shaft 111. The rotary polygon mirror 101 is covered with a substantially cylindrical cover 102, which restricts the flow of air accompanying the rotation of the rotary polygon mirror 101, reduces wind noise, and reduces wind noise to the outside. Prevent it from leaking. The cover 10
The second cylindrical portion 102a has a window 10 through which laser light passes.
3 is provided.

[0005]

However, according to the above-mentioned conventional technique, the air flowing inside the cover as the rotary polygon mirror rotates at a high speed flows out from the window through which the laser light passes. A large wind noise is generated due to friction with the peripheral edge of the, and becomes a cause of noise.

The present invention has been made in view of the above-mentioned problems of the prior art. When the air flowing inside the cover along with the high speed rotation of the rotary polygon mirror flows out from the window of the cover. It is an object of the present invention to provide an optical deflector capable of reducing the wind noise.

[0007]

In order to achieve the above object, an optical deflector according to the present invention comprises a rotary polygon mirror for deflecting and scanning the illumination light applied to the outer peripheral surface, and a cylindrical portion covering the outer peripheral surface. A cover, and a cylindrical portion of the cover is provided with an opening that allows the illumination light to pass therethrough and a substantially cylindrical protruding portion that surrounds the opening, and the protruding portion opens outside the opening. It is characterized by

It is preferable that the amount of protrusion of the protrusion is reduced in the direction opposite to the rotating direction of the rotary polygon mirror.

Further, the opening extends in the rotation direction of the rotary polygon mirror, and the protrusion extends along the tangent plane of the cylindrical portion of the cover from the edge of the opening in the direction opposite to the direction. It should be protruding.

[0010]

The air in the cover flows at a high speed as the rotary polygon mirror rotates at a high speed, and flows out through the opening of the cover.
The air flowing out from the opening swirls in the rotation direction of the rotary polygon mirror, flows outward along the protrusion, loses its flow velocity as it moves away from the rotary polygon mirror, and decelerates. Since the wind noise is smaller as the flow velocity of the air flowing out from the cover is slower, the wind noise can be reduced by providing the protrusion.

If the amount of protrusion of the protrusion is reduced in the direction opposite to the direction of rotation of the rotary polygon mirror, the space can be saved without significantly impairing the effect of wind noise reduction by the protrusion.

The opening extends in the direction of rotation of the rotary polygonal mirror, and the projection projects from the edge of the opening in the extension direction in the opposite direction along the tangential plane of the cylindrical portion of the cover. In this case, the wind noise can be further reduced by increasing the radial protrusion amount of the protrusion in the rotation direction of the rotary polygon mirror.

[0013]

Embodiments of the present invention will be described with reference to the drawings.

FIGS. 1 to 3 are a partial schematic sectional view and a partial schematic perspective view showing the main part of one embodiment in two different cross sections, and the optical deflector of the present embodiment is driven by a driving mechanism (not shown). The rotary polygon mirror 1 that is rotated in the direction of arrow A, and a substantially cylindrical cover 2 that covers the rotary polygon mirror 1 are provided.
Has a cylindrical wall 2a, which is a cylindrical portion, and a disk-shaped top wall 2b. It has a window 3 which is an opening for passing the laser light imaged on the photosensitive drum through the image lens. Window 3
Is surrounded by a soundproof hood 4 which is a substantially cylindrical protruding portion integrally provided with the cylindrical wall 2a of the cover 2, and the soundproof hood 4 has a cross section having substantially the same shape as the opening shape of the window 3. , Projecting radially outward from the cylindrical wall 2a of the cover 2,
It has an open end 4a that opens in substantially the same direction as the window 3.

When the rotary polygon mirror 1 rotates at a high speed, the air inside the cover 2 flows at a high speed accordingly, and a part of the air passes through the soundproof hood 4 from the window 3 of the cover 2 and its opening end 4 opens.
It flows out from a. As described above, the soundproof hood 4 projects radially outward from the cylindrical wall 2a of the cover 2, so that the air flowing out from the open end 4a of the soundproof hood 4 flows inside the soundproof hood 4. In the meantime, it loses some of its flow velocity and slows down. To this end, the window 3 through the cover 2
The friction between the air flowing out to the outside and the opening end 4a of the soundproof hood 4 and the wind noise due to the vortex of the air generated around the window 3 can be significantly reduced. Further, since the soundproof hood 4 absorbs a part of the wind noise due to the friction between the rotary polygon mirror 1 and the air in the sound hood 4, the wind noise leaking from the cover 2 to the outside can be reduced. According to the experiment, it was found that the noise is reduced by 4 to 8 dB by providing the soundproof hood of this example.

Next, a modification of this embodiment will be described.

FIGS. 4 and 5 show a first modified example, in which the cover 12 of this modified example has a substantially cylindrical soundproof hood 4 having a cross section that is substantially the same as the opening shape of the window 3 of this embodiment. Instead, of the both side edges 13 a and 13 b of the window 13, the side edge 13 b on the downstream side in the rotation direction of the rotary polygon mirror 11 is moved to the cover 12.
Side wall 14b protruding in the tangential direction of the cylindrical wall 12a, and a substantially triangular top wall 14 integrally provided at the upper and lower ends in the figure.
A beak-shaped soundproof hood 14 composed of c and a bottom wall 14d is provided. In the soundproof hood 14 of the present modification, the amount of protrusion is reduced in the direction opposite to the rotation direction of the rotary polygon mirror 11, and since the side edge 13a on the upstream side of the window 13 does not have a protrusion, the lens is located in this vicinity. Etc. can be provided close to each other.

FIGS. 6 and 7 show a second modified example, in which the cover 22 of this modified example extends a window 23 similar to the window 3 of the above-described embodiment to the downstream side in the rotational direction, and A side wall 24b of the soundproof hood 24, which is similar to the soundproof hood 4 of the embodiment, on the downstream side in the rotation direction of the rotary polygon mirror 21 is covered.
By arranging along the tangential plane of the two cylindrical walls 22a, the cross section of the soundproof hood 24 is enlarged toward the rotational direction of the rotary polygon mirror 21. The air flowing out from the cover 22 through the window 23 swirls in the above-mentioned direction and is discharged beyond the end line of the side wall 24b on the downstream side of the soundproof hood 24, so that noise due to wind noise is further reduced.

[0019]

Since the present invention is configured as described above, it has the following effects.

It is possible to reduce wind noise when the air flowing inside the cover of the rotary polygon mirror as the rotary polygon mirror rotates at high speed flows out from the opening of the cover. As a result, an optical deflector with less noise can be realized.

[Brief description of drawings]

FIG. 1 is a partial schematic cross-sectional view showing a main part of one embodiment.

FIG. 2 is a partial schematic cross-sectional view showing the main part of one embodiment in another cross section.

FIG. 3 is a partial schematic perspective view showing a main part of one embodiment.

FIG. 4 is a partial schematic cross-sectional view showing a main part of a first modified example.

FIG. 5 is a partial schematic perspective view showing a main part of a first modified example.

FIG. 6 is a partial schematic cross-sectional view showing a main part of a second modification.

FIG. 7 is a partial schematic perspective view showing a main part of a second modified example.

FIG. 8 is a partial schematic cross-sectional view showing a conventional example.

FIG. 9 is an explanatory diagram illustrating an entire optical deflector.

[Explanation of symbols]

 1,11,21 rotating polygon mirror 2,12,22 cover 2a, 12a, 22a cylindrical wall 3,13,23 window 4,14,24 soundproof hood

Front page continuation (72) Inventor Hideyuki Miyamoto 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Yasuo Suzuki 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Kenichi Tomita 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (3)

[Claims] 1. A rotary polygonal mirror for deflecting and scanning illumination light applied to an outer peripheral surface, and a cover having a cylindrical portion covering the outer peripheral surface, the illumination light passing through the cylindrical portion of the cover. An optical deflector comprising an opening and a substantially cylindrical projection surrounding the opening, the projection being open to the outside of the opening. 2. The optical deflector according to claim 1, wherein the amount of protrusion of the protrusion is reduced in the direction opposite to the rotating direction of the rotary polygon mirror. 3. The opening extends in the rotational direction of the rotary polygon mirror, and the protrusion extends from the edge of the opening in the direction opposite to the direction along the tangential plane of the cylindrical portion of the cover. The optical deflector according to claim 1, wherein the optical deflector is projected.