JPH07175004A - Deflection and scanning device - Google Patents

Abstract

PURPOSE:To reduce the light quantity of a laser beam by an ND filter cap provided on a rotary polygon mirror. CONSTITUTION:The rotary polygon mirror 1 is integrated with a rotor 4 and the outside circumferential surface 1a thereof is covered with the ND filter cap 8. The cap 8 is fixed to the mirror 1 by a catch 8c. When a current is supplied to the coil 6a of a stator 6, the rotor 11 and the mirror 1 are integrally rotated. When the laser beam with which the outside circumferential surface 1a of the mirror 1 is irradiated is transmitted through the cap 8, the light quantity thereof is reduced. Then, the image thereof is formed on a photoreceptor on a photoreceptive drum through an image forming lens system.

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 in laser printers, laser facsimiles and the like.

[0002]

2. Description of the Related Art In a deflection scanning device used for a laser printer, a laser facsimile, etc., as shown in FIG. 5, a laser beam L ₁ generated from a semiconductor laser S is collimated by a collimator lens (not shown) and then cylindrical. The light is condensed linearly by the lens C and is irradiated onto each mirror surface 101a on the outer peripheral surface of the rotary polygon mirror 101. The laser beam L ₂ deflected by the rotation of the rotary polygon mirror 101 is imaged on the photoconductor on the rotary drum D via the imaging lens F and the folding mirror M, and the main scanning by the rotation of the rotary polygon mirror 101 and the rotary drum D. An electrostatic latent image is formed by sub-scanning by rotation of the. Further, a part of the laser light L ₂ deflected by the rotary polygon mirror 101 is reflected by the detection mirror N to the light receiving end of the optical fiber G, and is input to the semiconductor laser S as a write start signal. The rotary polygon mirror 101,
The imaging lens F, the folding mirror M, the detection mirror N, the optical fiber G, etc. are housed in the optical box E, and the semiconductor laser S is mounted on one side wall of the optical box E. Further, on the bottom wall of the optical box E, there is provided an extraction window W for the laser light L ₃ reflected from the folding mirror M toward the rotary drum D.

The drive system for rotating the rotary polygon mirror 101 is
As shown in FIG. 6, the rotor 104 integrated with the shaft 103 supported by the bearing 105 and the housing 1 of the bearing 105.
The rotor 1 comprises a stator 106 fixed to 05a.
04 and the stator 106 constitute a motor that rotationally drives the rotary polygon mirror 101. That is, the magnet 104a of the rotor 104 and the coil 106a of the stator 106 are disposed so as to face each other, and the rotary polygon mirror 101 is pressed against the rotor 104 by the leaf spring 102 and integrally coupled with the rotor 104, so that the coil 106a of the stator 106 is When a current is supplied from a drive circuit (not shown) on the substrate 107 on which the rotor is mounted, the rotor 104 and the rotary polygon mirror 101 rotate together.

The semiconductor laser S also has a light quantity adjusting device for adjusting the quantity of light emitted from the laser light L ₁ in accordance with the quantity of light required for the photosensitive member of the rotary drum D. In recent years, a high-sensitivity photoconductor is often used along with higher definition of printing in a laser printer, a laser facsimile, etc., and the required light amount of the photoconductor tends to decrease.

[0005]

However, according to the above-mentioned conventional technique, as described above, when the required light amount of the photoconductor is lowered with the high definition of printing, the light emitting device adjusts the light emitting amount of the semiconductor laser. This is not enough, and it is necessary to take measures such as coating the folding mirror to reduce the reflectance. In addition, recently, the speed of the deflection scanning device has been increased, and the rotating polygon mirror is operated at 10,000 rpm.
It is required to rotate at a high speed of 20,000 rpm or more, but when the rotating polygon mirror is rotated at such a high speed, wind noise increases and dust in the air adheres to each mirror surface. As a result, the reflectance may become uneven.

The present invention has been made in view of the above problems of the prior art, and can effectively reduce the amount of laser light in accordance with the required amount of light of the photosensitive member and contaminate the mirror surface of the rotating polygon mirror. It is an object of the present invention to provide a deflection scanning device capable of preventing the above.

[0007]

In order to achieve the above object, a deflection scanning device of the present invention comprises a rotary polygonal mirror having at least one mirror surface on its outer peripheral surface, and a light reflected by the mirror surface of the rotary polygonal mirror. It is characterized in that it has a photosensitive means for receiving light, and at least the mirror surface of the rotary polygonal mirror is covered by an optical filter means having a predetermined light transmittance.

The optical filter means may be a part of a detachable cap member that covers at least the outer peripheral surface of the rotary polygon mirror.

Further, it is preferable that the cap member has a cylindrical outer peripheral surface.

[0010]

According to the above apparatus, the light quantity of the light received by the photosensitive means can be reduced by the optical filter means provided on the mirror surface according to the required light quantity of the photosensitive means.

Further, since the mirror surface is covered with the optical filter means, it is possible to prevent contamination by dust or the like in the air.

If the optical filter means is at least a part of the detachable cap member that covers at least the outer peripheral surface of the rotary polygon mirror, the optical filter means can be easily replaced according to the required light quantity of the photosensitive means.

[0013]

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

FIG. 1 is a partial schematic cross-sectional view showing a main part of a deflection scanning device according to an embodiment. A polygonal prism rotary polygon mirror 1 having six mirror surfaces on an outer peripheral surface 1a is formed by a leaf spring 2. The rotor 4 that is integral with the shaft 3 is pressed and integrally coupled thereto. The rotor 4 rotates the rotary polygon mirror 1 together with the stator 6 that is integral with the housing 5a of the bearing 5 that supports the shaft 3. To configure the motor. That is, the rotor 4 has a magnet 4a facing the coil 6a of the stator 6, and a motor drive circuit (not shown) is mounted on the substrate 7 supported by the housing 5a of the bearing 5.
The motor drive circuit supplies a drive current to the coil 6a of the stator 6.

The deflection scanning apparatus according to the present embodiment includes a semiconductor laser that generates laser light toward the rotary polygon mirror 1.
An imaging lens that forms an image of the laser light reflected by the rotary polygon mirror 1 on a photoconductor on a rotating drum that is a photosensing means via a folding mirror, and a part of the laser light is reflected by an optical fiber as a scanning start signal. It has a reflection mirror and the like, and the rotary polygon mirror 1, the imaging lens, the folding mirror, the reflection mirror, etc. are housed in an optical box, and the semiconductor laser is mounted on one side wall thereof.

The outer peripheral surface 1a of the rotary polygon mirror 1 is covered with an ND filter cap 8 which is a detachable cap member, and the ND filter cap 8 is attached to the rotary polygon mirror 1.
It serves to reduce the amount of laser light applied to each mirror surface of the outer peripheral surface 1a by a predetermined amount according to the required amount of light of the photoconductor, and the material of the ND filter cap 8 is Accordingly, one having a predetermined light transmittance is selected.

The ND filter cap 8 has a disc portion 8a which abuts on the top surface 1b of the rotary polygon mirror 1, a main body 8b having a cylindrical surface which is integral with the disc portion 8a, and an integral body 8b. The stopper 8c is provided, and the disk portion 8a, the main body 8b, and the locking claw 8c are integrally formed by an ND filter material (a density conversion filter that changes the amount of transmission) that is an optical filter material. The locking claw 8
c is elastically locked to the bottom surface 1c of the rotary polygon mirror 1, and the number thereof is not limited to one, and a predetermined number is provided at the lower end of the main body 8b as necessary.

The main body 8b of the ND filter cap 8 is
As shown in FIG. 3, it has a hexagonal columnar inner surface 8d slidably fitted on the outer peripheral surface 1a of the rotary polygon mirror 1. The procedure for attaching the ND filter cap 8 to the rotary polygon mirror 1 is as follows. With the locking claw 8c deformed outward in the circumferential direction, the ND filter cap 8 is placed on the rotary polygonal mirror 1 and slid in the axial direction, and the disc portion 8a of the ND filter cap 8 is moved to the rotary polygonal mirror 1's side. When it comes into contact with the top surface 1b, the locking claw 8c is released to the shape before deformation. The outer peripheral surface 1a of the rotary polygon mirror 1 is in close contact with the inner surface 8d of the ND filter cap 8, and the disc portion 8a of the ND filter cap 8 is also included.
It is firmly connected to the ND filter cap 8 by being sandwiched between the locking claw 8c and the locking claw 8c, and there is no fear of rattling even during high speed rotation.

According to this embodiment, it is possible to easily reduce the light amount of the laser beam for deflection scanning simply by mounting the ND filter cap on the rotary polygon mirror, and at the same time, the outer circumference including each mirror surface and the ridge angle of the rotary polygon mirror. Since the entire surface is covered with the cylindrical ND filter cap, wind noise is significantly reduced, and in addition, there is no possibility that each mirror surface is contaminated by dust or the like in the air. Further, when the ND filter cap is contaminated by the dust or the like, it can be easily replaced. Further, when the required amount of light on the photosensitive member of the photosensitive drum changes, it can be easily replaced with an ND filter cap having a different light transmittance.

Although the ND filter cap of this embodiment has a main body having a cylindrical surface, it goes without saying that the surface of the main body can be made into a polygonal column shape in accordance with the shape of the outer peripheral surface of the rotary polygon mirror.

FIG. 4 is a perspective view showing an ND filter cap according to a modification of the present embodiment, which is a rotary polyhedral surface (not shown) of a main body 18b of the ND filter cap 18 similar to the ND filter cap of the present embodiment. Only the arcuate portion 18e that is in contact with each mirror surface of the mirror is made of an ND filter material, and the disk portion 18a, the locking claw 18c and the rest of the body 18b are made of a resin material such as polycarbonate. .

[0022]

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

The amount of laser light can be effectively reduced in accordance with the required amount of light on the photosensitive member, and the mirror surface of the rotary polygon mirror can be prevented from being contaminated by dust in the air. Further, the light amount of the laser light can be changed by replacing the detachable cap member. Further, it is easy to reduce the wind noise of the rotary polygon mirror. As a result, it is possible to realize a high-performance deflection scanning device which is low in noise and inexpensive.

[Brief description of drawings]

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

2 is a perspective view showing only the ND filter cap of the apparatus of FIG. 1. FIG.

FIG. 3 is a perspective view showing the ND filter cap of FIG. 2 upside down.

FIG. 4 is a perspective view showing an ND filter cap according to a modification.

FIG. 5 is a perspective view showing the entire deflection scanning device.

FIG. 6 is a partial schematic cross-sectional view showing a rotary polygon mirror and a drive unit thereof according to a conventional example.

[Explanation of reference numerals] 1 rotary polygon mirror 1a outer peripheral surface 2 leaf spring 3 axis 4 rotor 4a magnet 5 bearing 5a housing 6 stator 6a coil 7 substrate 8, 18 ND filter cap 8a, 18a disc portion 8b, 18b main body 8c, 18c Locking claw

Claims (4)

[Claims] 1. A rotary polygonal mirror having at least one mirror surface on an outer peripheral surface thereof, and a photosensitive means for receiving reflected light from the mirror surface of the rotary polygonal mirror, wherein at least the mirror surface of the rotary polygonal mirror has a predetermined shape. The deflection scanning device is characterized in that it is covered by an optical filter means having the above-mentioned light transmittance. 2. The deflection scanning device according to claim 1, wherein the optical filter means is a part of a detachable cap member which covers at least the outer peripheral surface of the rotary polygon mirror. 3. The deflection scanning device according to claim 2, wherein the entire cap member is made of an optical filter material having a predetermined light transmittance. 4. The deflection scanning device according to claim 2, wherein the cap member has a cylindrical outer peripheral surface.