JPH08136844A - Optical deflector - Google Patents

Abstract

(57) [Abstract] [Purpose] The cover member of the rotating polygon mirror and the optical member such as the cylindrical lens are integrated. The laser beam L ₁ is deflected and scanned by the rotary polygon mirror 1, and forms an image on a photoconductor of a rotary drum via a spherical lens 7a and a toric lens 7b. The rotary polygon mirror 1 and its drive unit are covered with a cover member 2, and the laser light L
Plastic cylindrical lens 5 for condensing the ₁ linearly on the reflecting surface 1a of the rotary polygon mirror 1 is integrally molded with the cover member 2. Since it is not necessary to individually assemble the cylindrical lens 5, it is possible to reduce the number of assembly parts and simplify the assembly process.

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 light beam such as a laser beam at a high speed in an image forming apparatus such as a laser printer.

[0002]

2. Description of the Related Art In recent years, the speed of optical deflectors such as laser printers and laser facsimiles has become particularly high, and the rotating polygon mirrors used in these deflectors perform high-speed rotations 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 member.

FIG. 6 illustrates a general optical deflector as a whole. A laser oscillator 11 mounted on an optical box 100 is shown.
Laser light L ₀ generated from laser beam ₀ is focused into a predetermined beam shape by a cylindrical lens 105, then deflected and scanned by a rotary polygon mirror 101, and the spherical lens 10
An image is formed on the photosensitive drum 107 via an image forming lens system 106 composed of 6a and a toric lens 106b. A part of the laser light reflected by the rotary polygon mirror 101 is introduced into the optical fiber 109 by the reflection mirror 108 and converted into a scanning start signal.

FIG. 7 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 101 includes a bearing device 113 that supports the rotary shaft 111, a stator coil 114, and a circuit board 115 that supplies a drive current to the stator coil 114.
By the pressing mechanism 116 including the corrugated washer 116a, the flat washer 116b, and the retaining ring 116c, the rotating shaft 11
It is pressed by the flange member 111a that is integral with the shaft 1 and is thereby integrated with the rotary shaft 111. The rotary polygon mirror 101 is covered with a substantially cylindrical cover member 102, which limits the flow of air accompanying the rotation of the rotary polygon mirror 101 and reduces the generation of wind noise.
Prevents wind noise from leaking to the outside. The cover member 10
The second cylindrical portion 102a has a window 10 through which laser light passes.
3 is provided.

Further, recently, as shown in FIG. 8, there has been developed one in which a cylindrical lens 205 is attached to an opening 202a on a laser beam introducing side of a cover member 202. In this case, it is general that the cylindrical lens 205 is pressed against the outer surface of the cover member 202 by the pressing member 205a to be integrated with the cover member 202.
Further, the opening 202 on the laser light extraction side of the cover member 202
b is covered with dust-proof glass 207 to reduce the amount of air sucked into the cover member 202 as the rotary polygon mirror 201 rotates, to prevent contamination of the reflecting surface 201a of the rotary polygon mirror 201 and during rotation of the rotary polygon mirror 201. It is designed to reduce wind noise.

[0006]

However, according to the above conventional technique, the cover member and the cylindrical lens are manufactured as separate members, and the cylindrical lens is integrated with the cover member by the pressing member or the like. Therefore, the assembly process is complicated. In addition, since the cover lens is attached to the housing of the optical deflector after the cylindrical lens and dustproof glass are attached to the cover member, the position of the cylindrical lens is displaced during the work, and the light of the cylindrical lens is again generated. There is an inconvenience that axis alignment is required. Further, the pressing force of the pressing member or the like may cause distortion in the cylindrical lens, which may deteriorate the optical characteristics of the cylindrical lens.

The present invention has been made in view of the above-mentioned problems of the prior art. An optical member such as a cylindrical lens is integrated with a cover member, so that they can be easily assembled and assembled. It is an object of the present invention to provide an optical deflector in which the number of parts is significantly reduced, and the optical characteristics of the optical deflector are not deteriorated by the assembly of the optical members.

[0008]

In order to achieve the above object, an optical deflector of the present invention comprises a light source, a rotary polygon mirror for deflecting and scanning a light beam generated from the light source toward a photoconductor, and A cover member surrounding the rotary polygonal mirror, at least one optical member made of plastic is disposed in the optical path of the light beam, and the optical member is integrally molded with the cover member. And

Further, it is preferable that the optical member is a cylindrical lens for linearly focusing the light beam toward the rotary polygon mirror.

The optical member may be a lens arranged between the rotary polygon mirror and the photoconductor.

Further, guide means for guiding the cover member along the optical axis of the optical member may be provided.

[0012]

The number of parts to be assembled is greatly reduced by integrally molding the cover member for preventing the contamination of the reflecting surface of the rotating polygon mirror and the noise during rotation and the optical member such as the plastic cylindrical lens.

Since it is not necessary to individually assemble the optical members such as the cylindrical lens only by assembling the cover member, the assembling process is greatly simplified.

In addition, unlike the case where a plastic optical member is assembled by a pressing member or the like, there is no possibility that the optical member is deformed due to the pressing force of the pressing member and the optical characteristics thereof are deteriorated.

Further, if the guide means for guiding the cover member along the optical axis of the optical member is provided, the optical member can be easily focused on the rotary polygon mirror or the like when the cover member is assembled. .

[0016]

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

FIG. 1 is a schematic partial sectional view showing the main part of the optical deflector according to the first embodiment, which shows a laser beam L ₁ which is a light beam generated from a laser oscillator which is a light source (not shown). A rotary polygon mirror 1 for deflecting and scanning toward a photoconductor of a rotary drum (not shown), a drive unit (not shown) for rotating the same, and a cover member 2 for covering the drive unit and the rotary polygon mirror 1 are provided. A cylindrical portion 2a that is made of a transparent plastic material and surrounds the reflecting surface 1a of the rotary polygon mirror 1 and a disc-shaped top plate 3 (see FIG. 2), and a bottom flange that is the lower end and one end of the cylindrical portion 2a. It is equipped with 4.

The cylindrical portion 2a of the cover member 2 includes, as a part thereof, a cylindrical lens 5 which is a plastic optical member for condensing the laser beam L ₁ only in the axial direction of the rotary polygon mirror 1, and the rotary polygon mirror 1. The thin dustproof plate 6 that covers the window 2b that takes out the deflected and scanned laser light from the cover member 2 is integrally formed.
It is attached to a housing (not shown) by screws that penetrate through the through holes 4a provided in the bottom flange 4.

Between the rotary polygon mirror 1 and the photoconductor, a spherical lens 7a for focusing the scanning light L ₂ deflected and scanned by the rotary polygon mirror 1 on the photoconductor and a toric lens 7b which is a kind of anamorphic lens are provided. The so-called fθ function for eliminating the change in the scanning speed of the scanning light L ₂ and the so-called f-function for preventing the positional deviation of the point image due to the surface tilt of the rotary polygon mirror 1 like the cylindrical lens 5 are provided. Has a function to correct face tilt.

A protrusion 5a is provided on the outer peripheral edge of the cylindrical lens 5, and the protrusion amount of the protrusion 5a is larger than the central portion of the cylindrical lens 5 having the largest protrusion amount by a predetermined amount Δm, as shown in FIG. When the cover member 2 is set in the housing and the operator's hand or equipment is set in the cylindrical lens 5 during the maintenance work of the device.
It is configured so that it can be prevented from swinging directly to the surface of.

Similarly, a projection 6a projecting from the dustproof plate 6 by a predetermined amount is also arranged around the dustproof plate 6 to prevent the dustproof plate 6 from being contaminated or damaged during assembly or maintenance work. Has been done.

When it is necessary to positively introduce the outside air into the cover member 2 to cool the drive member of the rotary polygon mirror 1 and the like, the dustproof plate 6 is omitted and the window 2b is opened. It is desirable to leave it as it is.

According to this embodiment, since the cover member for covering the periphery of the rotary polygon mirror and preventing the noise due to the pollution of the reflecting surface and the wind noise, the cylindrical lens and the dustproof plate are integrally molded, these components are integrally formed. When assembling, the cover member need only be assembled to the housing. Unlike the conventional example, it is not necessary to assemble the cylindrical lens and the dustproof plate individually, so the assembly process is simple and the number of parts to be assembled is small, and the mounting position of the cylindrical lens may shift during the assembly work of the cover member. Also, there is no possibility that the optical characteristics of the cylindrical lens will deteriorate due to the pressing force of the pressing member for assembling the cylindrical lens.

As a result, an inexpensive and high-performance optical deflector can be realized.

In this embodiment, the cover member, the cylindrical lens and the dustproof plate are integrally molded, but as described above, only the cover member and the cylindrical lens are integrally molded and the dustproof plate is omitted. Good and also
A collimator lens for collimating the laser beam L ₁ generated from the laser oscillator may be integrated with the cylindrical lens, and the integrated anamorphic lens may be integrally molded with the cover member.

FIG. 4 shows a modified example, in which the cylindrical lens 5 is provided on the bottom flange 4 of the cover member 2.
Is provided with a pair of elongated holes 4b which are guide means extending in the optical axis direction, and each elongated hole 4b is engaged with a positioning pin (not shown) which is integral with the housing to move the cover member 2 in the optical axis direction. The cylindrical lens 5 is configured to be focused on the rotary polygon mirror 1, and in addition, the cover member 2 is used.
The concave and convex portions 8 are formed on the inner surface of the cylindrical portion 2a to scatter the light reflected by the inner surface of the cover member 2 to reduce disturbance.

FIG. 5 is a schematic partial sectional view showing the main part of the optical deflector according to the second embodiment, which covers the spherical lens 17a which is a lens instead of the dustproof plate 6 of the first embodiment. It is provided integrally with the member 12. Projection amount Δn of the projection 17b arranged on the outer peripheral edge of the spherical lens 17a
Needless to say, similarly to the projection 5a of the cylindrical lens 5, is set to be larger than the central portion where the spherical lens 17a has the largest projection amount.

Since the rotary polygon mirror 1, the cylindrical lens 5 and the like are the same as those in the first embodiment, they are designated by the same reference numerals and their description will be omitted.

[0029]

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

Since the optical member such as the cylindrical lens is integrated with the cover member, there is no fear that the optical characteristics will be deteriorated due to the assembly of the optical member, the number of assembling parts is greatly reduced, and the assembling process is also drastically reduced. It is simplified.

As a result, an inexpensive and high-performance optical deflector can be realized. Use of such an optical deflector can greatly contribute to cost reduction and high performance of the image forming apparatus.

[Brief description of drawings]

FIG. 1 is a schematic partial sectional view showing a main part of an optical deflector according to a first embodiment.

FIG. 2 is a perspective view of the cover member of FIG.

FIG. 3 is an enlarged schematic partial cross-sectional view taken along the line AA of FIG.

FIG. 4 is a schematic partial sectional view showing a main part of an optical deflector according to a modification.

FIG. 5 is a schematic partial sectional view showing a main part of an optical deflector according to a second embodiment.

FIG. 6 is a diagram illustrating an entire optical deflector.

FIG. 7 is a schematic partial sectional view showing a main part of an optical deflector according to a conventional example.

FIG. 8 is a schematic partial sectional view showing a main part of an optical deflector according to another conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 rotary polygon mirror 2, 12 cover member 2a cylindrical part 4 bottom flange 4b long hole 5 cylindrical lens 5a, 6a, 17b protrusion 6 dustproof plate 7a, 17a spherical lens 7b toric lens

Claims (4)

[Claims] 1. A light source, a rotary polygonal mirror for deflecting and scanning a light beam generated from the light source toward a photosensitive member, and a cover member surrounding the rotary polygonal mirror, and at least in an optical path of the light beam. An optical deflector in which one plastic optical member is provided, and the optical member is integrally molded with the cover member. 2. The optical deflector according to claim 1, wherein the optical member is a cylindrical lens that linearly focuses the light beam toward the rotary polygon mirror. 3. The optical deflector according to claim 1, wherein the optical member is a lens disposed between the rotary polygon mirror and the photoconductor. 4. The optical deflector according to claim 1, further comprising guide means for guiding the cover member along the optical axis of the optical member.