JPH11337856A - Scanning optical device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid the movement of the position of a scanning beam and the variance of the beam diameter. SOLUTION: When a luminous flux reflected and scanned on the reflection face of a rotary polygon mirror 5 passes a first image forming lens 31 and a second image forming lens 32, an optical path passing the vicinity of an adhesion projecting face 35a of the second image forming lens is made to be at a position distant from an adhesion projecting face 33a of the first image forming lens, and an optical path passing the vicinity of an adhesion projecting face 35b of the second image forming lens is made to be at a position distant from an adhesion projecting face 33b of the first image forming lens.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanning optical device used for a laser beam printer, a laser facsimile or the like.

[0002]

2. Description of the Related Art Conventionally, in a scanning optical device used for a laser beam printer, a laser facsimile, or the like, an electrostatic latent image is formed by scanning a photosensitive member with a light beam deflected by a deflector. Is visualized into a toner image by a developing device, transferred to a recording paper, and the toner is heated and fixed by a fixing device, thereby performing printing on the recording paper.

FIG. 4 is a plan view of a conventional scanning optical device. An optical box 1 has a laser holder 2 having a semiconductor laser light source, and a laser beam converted into a parallel light beam along an optical path of a light beam generated from the semiconductor laser light source. A collimator lens 3, a composite lens 4 integrally formed with a cylindrical lens 4 a and a BD lens 4 b for condensing a parallel light beam from the collimator lens 3 into a line, and a line image formed by being condensed by the cylindrical lens 4 a , A rotating polygon mirror 5 having a deflecting / reflecting surface 5a in the vicinity, a motor 6 for rotating and driving the rotating polygon mirror 5, a first imaging lens 7, a second imaging lens 8, A deflecting surface reflecting mirror 9 and the like are arranged. And the BD of the compound lens 4
A BD light receiving unit 10 is arranged on a part of the laser holder 2 on the optical path of the lens 4b, and is set as a trigger indicating a writing start timing of the scanning light.

The first imaging lens 7 is provided with a flange surface on both the upper side and the lower side of the lens portion, and abutment reference shape portions in the optical axis direction are provided on both ends in the longitudinal direction. The lower flange is provided with a center positioning protrusion 11 and adhesive protrusion surfaces 12a and 12b.
3, the position of the center of the first imaging lens 7 in the longitudinal direction is set. Further, abutment reference portions 14a and 14b in the height direction are formed on the optical box 1, and the lower flange surface of the first imaging lens 7 abuts on the upper surface thereof, thereby providing the first image forming lens 7. The optical axis height of the imaging lens 7 is set. Further, the abutting reference surfaces at both ends of the first imaging lens 7 correspond to the projecting rib-shaped portions 15a, 15a of the optical box 1.
b, the position of the first imaging lens 7 in the optical axis direction is set. Adhesive seat surfaces 16a, 16b on optical box 1
Is set several tens μm lower than the abutment reference portions 14a and 14b in the height direction. An ultraviolet curing adhesive or the like is applied to this portion, and the adhesive projection surface 12a of the first imaging lens 7 is 12b is adhesively fixed.

[0005] The second imaging lens 8 is also the first imaging lens 7
Similarly to the above, it is fixed to the optical box 1. The center positioning projection-shaped portion 1 is provided on the lower flange portion of the second imaging lens 8.
7 and adhesive protrusion surfaces 18a and 18b are provided, and the center positioning protrusion shape portion 17 is sandwiched between positioning pins 19 on the optical box 1 side. The optical box 1 is formed with abutment reference portions 20a and 20b in the height direction, and the lower flange surface of the second imaging lens 8 is in contact with the upper surface thereof. The abutment reference surfaces at both ends of the second imaging lens 8 abut against the protruding rib-shaped portions 21a and 21b,
The adhesive seating surfaces 22a and 22b are set several tens μm lower than the abutment reference portions 20a and 20b. And the first
Adhesive projection surface 18 of the imaging lens 7 and the second imaging lens 8
a, 12b, and 18b are arranged on substantially the same optical path formed by the rotational scanning of the rotary polygon mirror 5, as indicated by the dashed line.

With this configuration, the laser light from the semiconductor laser light source passes through the urimeter lens 3 and the cylindrical lens 4a, and passes through the deflecting and reflecting surface 5 of the rotary polygon mirror 5.
The light is deflected and reflected by a, and passes through the opening of the optical box 1 via the first imaging lens 7, the second imaging lens 8, and the surface reflection mirror 9, and is irradiated onto the photosensitive member. At this time, the deflection reflecting surface 5
A part of the laser light reflected by a enters the BD light receiving unit 10 on the laser holder 2 via the BD lens 4b, and the writing timing of the scanning laser light is set. The scanning laser light deflected and reflected by the deflecting reflection surface 5a is condensed by the first imaging lens 7 and the second imaging lens 8 so as to form a spot on the photoreceptor and scanned at a constant speed. . That is, the main scanning is performed by the rotation of the rotary polygon mirror 5,
The photoreceptor is driven to rotate about the axis of the cylinder to perform sub-scanning. Thus, an electrostatic latent image is formed on the surface of the photoconductor.

[0007]

However, since the length of the lens used in the above-described conventional scanning optical system is generally proportional to the installation distance in the optical axis direction from the deflecting surface, a plurality of lenses are required. If the adhesive projection surface, the positioning shape, and the like are provided at positions proportional to the external shape of the lens, the projection shape portions of the respective lenses will be located substantially on the same optical path. If the plastic lens has a part where the thickness changes or the part is asymmetrical in the external shape, a delicate surface of the lens near that part due to the influence of the fluidity of the material or the cooling time of the mold, etc. Optical discontinuities occur. If there is such a discontinuous portion, the beam position at the scanning position moves or the beam diameter changes, resulting in an inconvenient image having uneven density or the like. In particular, in an optical system using a plurality of plastic lenses, discontinuous portions are arranged on the same optical path, which causes a problem that a defect is doubled and an image is further deteriorated.

An object of the present invention is to solve the above-mentioned problems,
An object of the present invention is to provide a scanning optical apparatus in which the position of a scanning beam moves and the beam diameter does not change much.

[0009]

A scanning optical apparatus according to the present invention for achieving the above object has a laser light emitting means and a laser light deflecting means, and uses a plurality of lenses to receive laser light. In a scanning optical device that scans at a constant speed on a body, an irregularly shaped portion is formed on each of the plurality of lenses, and the plurality of lenses are arranged so that the irregularly shaped portion deviates from the same scanning optical path. Features.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the embodiments shown in FIGS. FIG. 1 is a plan view of the first embodiment. In the present embodiment, the same components as those in the conventional example of FIG. 4 are denoted by the same reference numerals except for the first and second imaging lenses. Only different parts will be described.

The optical box 30 includes a laser holder 2, a collimator lens 3, and a cylindrical lens 4 as in FIG.
a and a lens 6 composed of a BD lens 4b and a motor 6
Together with the rotating polygon mirror 5, the surface reflecting mirror 9, etc.
And the second imaging lens 32 are arranged.

The first imaging lens 31 is provided with adhesive projection surfaces 33a and 33b protruding in the optical axis direction, and the optical box 30 has an adhesive seat surface at a position corresponding to the adhesive projection surfaces 33a and 33b. 34a and 34b are provided, and the first imaging lens 31 is attached to the optical box 3 by bonding the adhesive projection surfaces 33a and 33b to the adhesive seat surfaces 34a and 34b, respectively.
0 is fixed at a predetermined position.

Similarly, the second imaging lens 32 is also provided with adhesive projection surfaces 35a and 35b protruding in the optical axis direction, and the optical box 30 has an adhesive seat surface at a position corresponding to the adhesive projection surfaces 35a and 35b. 36a and 36b are provided, and the second imaging lens 32 is attached to the optical box 3 by bonding the adhesive projection surfaces 35a and 35b to the adhesive seat surfaces 36a and 36b, respectively.
0 is fixed at a predetermined position.

With such a configuration, the light beam reflected and scanned by the reflecting surface 5a of the rotary polygon mirror 5 is converted into the first image forming lens 31.
The optical path passing through the second imaging lens 32 is as shown by a dashed line. That is, the optical path passing near the adhesive projection surface 35 a of the second imaging lens 8 passes through a position of the first imaging lens 7 that is separated from the adhesive projection surface 33 a on the first imaging lens 7. Similarly, the optical path passing near the adhesive projection surface 35b of the second imaging lens 8 is also the first imaging lens 7
It passes through a position separated from the other upper adhesive projection surface 33b.

FIG. 2 is a perspective view of the imaging lens of the second embodiment viewed from the back side. The first imaging lens 41 and the second imaging lens 42 have adhesive projections projecting in the thickness direction. Face 4
3a, 43b and 44a, 44b are provided respectively,
The optical path passing through the adhesive projection surfaces 43a and 43b of the first imaging lens 41 is formed by the adhesive projection surfaces 44a and 44a of the second imaging lens 42.
44b so that the first imaging lens 41 and the second
Are formed.

FIG. 3 is a perspective view of the imaging lens according to the third embodiment viewed from the back side. The first imaging lens 51 and the second imaging lens 52 have light on the draft at the bottom. Adhesive projection surfaces 53a, 53b and 54a, 54b whose angles are changed to be parallel to the axis are provided, respectively. The optical path passing through the adhesive projection surfaces 53a, 53b of the first imaging lens 51 is connected to the adhesive projection surfaces 54a, 54 of the second imaging lens 52.
A first imaging lens 51 and a second imaging lens 52 are arranged so as not to pass through b.

In the above embodiment, the adhesive projection surface is formed as a deformed portion. However, the same effect can be obtained even when a deformed portion for positioning or preventing erroneous mounting is provided on a plurality of lenses.

[0018]

As described above, in the scanning optical apparatus according to the present invention, by disposing differently shaped portions on a plurality of lenses so as not to be arranged on the same optical path, optically discontinuous portions of the lenses can be obtained. Is prevented from simultaneously passing through, the fluctuation of the light beam caused by passing through the discontinuous portion is dispersed, and the deterioration of the image can be prevented.

[Brief description of the drawings]

FIG. 1 is a plan view of a first embodiment.

FIG. 2 is a perspective view of a second embodiment.

FIG. 3 is a perspective view of a third embodiment.

FIG. 4 is a plan view of a conventional example.

[Explanation of symbols]

30 optical box 31, 41, 51 first imaging lens 32, 42, 52 second imaging lens 33a, 33b, 35a, 35b, 43a, 43b, 4
4a, 44b, 53a, 53b, 54a, 54b Adhesive projection surface 34a, 34b, 36a, 36b Adhesive seat surface

Claims (5)

[Claims] 1. A scanning optical apparatus having a laser light emitting means and a laser light deflecting means, and scanning a laser beam at a constant speed on a photosensitive member using a plurality of lenses. A scanning optical device, wherein an irregularly shaped portion is formed, and the plurality of lenses are arranged so that the irregularly shaped portion deviates from the same scanning optical path. 2. The scanning optical device according to claim 1, wherein the irregularly shaped portion is formed to be convex or concave in the optical axis direction. 3. The scanning optical device according to claim 1, wherein the irregularly shaped portion is formed to be convex or concave in a height direction of the lens. 4. The scanning optical device according to claim 1, wherein the irregularly shaped portion is formed so as to have an angle change of a draft surface of the lens. 5. The scanning optical device according to claim 1, wherein the lens is a plastic lens.