Optical: systems and elements – Deflection using a moving element
Reexamination Certificate
1998-09-29
2001-01-30
Phan, James (Department: 2872)
Optical: systems and elements
Deflection using a moving element
C359S205100, C359S207110, C359S212100, C359S215100, C359S216100, C359S710000, C359S717000, C359S819000
Reexamination Certificate
active
06181455
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a cylindrical lens that is used in, e.g., an image forming apparatus, and linearly images a laser beam originating from a laser light source, and an optical scanning device that uses the cylindrical lens and images a laser beam, deflected by a deflection means, onto a surface to be scanned via an imaging lens.
2. Related Background Art
In a conventional optical scanning device used in an image forming apparatus, such as a laser printer or the like, as shown in, e.g.,
FIG. 1
, a laser unit
2
is fixed to a predetermined position of an optical frame
1
. A laser beam L coming from the laser unit
2
is linearly focused by a cylindrical lens
3
, is deflected by a polygonal mirror
4
, which is rotated by the drive force of a drive motor
5
, and forms a beam spot on a surface
8
to be scanned of a photosensitive body via imaging lenses
6
and
7
.
As shown in
FIG. 2
, the cylindrical lens
3
has an integrated structure obtained by adhering a first lens
3
a
having a positive refractive power, and a second lens
3
b
having a negative refractive power, to each other. When the cylindrical lens
3
is fixed to the optical frame
1
, an adhesive
9
is interposed between the optical frame
1
and cylindrical lens
3
, the position of the cylindrical lens
3
is adjusted to form a desired spot shape on the surface
8
to be scanned, and the lens
3
is then fixed.
However, the cylindrical lens
3
is adjusted before the adhesive
9
is set. During the adjustment, the adhesive
9
may enter the effective portion from a gap
3
c
between the first and second lenses
3
a
and
3
b
. For this reason, in the conventional optical scanning device, the adhesive that has entered the effective portion of the cylindrical lens
3
intercepts, refracts, and scatters the laser beam, and the spot image on the surface
8
to be scanned may deform. When such optical scanning device is used in the image forming apparatus, the image quality deteriorates.
SUMMARY OF THE INVENTION
It is an object of the present invention to solve the above-mentioned problem, and to provide a cylindrical lens that can prevent an adhesive from entering the gap between optical elements, and an optical scanning device using the lens.
In order to achieve the above object, according to the present invention, a cylindrical lens, which is comprised of a plurality of optical elements and linearly images a laser beam, comprises adhesive entrance preventing means for preventing an adhesive used for fixing the optical elements to an optical frame from entering a gap between the optical elements.
Also, an optical scanning device according to the present invention comprises a laser light source for emitting a laser beam, a cylindrical lens, which is comprised of a plurality of optical elements and linearly images a laser beam, deflection means for deflecting the laser beam coming from the cylindrical lens, an imaging lens for imaging the laser beam from the deflection means on a surface to be scanned, an optical frame for holding the cylindrical lens, and adhesive entrance preventing means for preventing an adhesive, used for fixing the cylindrical lens to the optical frame, from entering a gap between the optical elements.
REFERENCES:
patent: 0 493 805 (1992-07-01), None
patent: 9-184997 (1997-07-01), None
patent: 9-184996 (1997-07-01), None
patent: 9-243947 (1997-09-01), None
Patent Abstracts of Japan, vol. 97, No. 11 (JP 9-184997, Jul. 15, 1997), Nov. 28, 1997.
Patent Abstracts of Japan, vol. 98, No. 1 (JP 9-243947, Sep. 19, 1997), Jan. 30, 1998.
Patent Abstracts of Japan, vol. 97, No. 11 (JP 9-184996, Jul. 15, 1997), Nov. 28, 1997.
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Phan James
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