JPH0384513A - Lens holding structure for optical writing means - Google Patents

Abstract

PURPOSE:To securely position and hold a lens without distorting the lens nor causing an adhesive to peel by providing a recessed part in the lengthwise center of the lens and fitting the lens at the recessed part with the adhesive. CONSTITUTION:The long-sized f-theta lens 34 is made of plastic and the recessed part 34a is formed cylindrically in the lengthwise center part. The diameter size (a) of the recessed part 34 is made a little bit larger than that of a lens holding part 40a. The recessed part 34a of the f-theta lens 34 is made to abut on the lens holding part 40a and the f-theta lens 34 is fitted to the lens holding part 40a with the adhesive 41. Both end parts of the f-theta lens 34 are mounted on a lens mount part 40b, and both end surfaces of the f-theta lens 34 are sandwiched between positioning parts 40c and positioned lengthwise. Consequently, the lens is securely held without distorting the lens nor causing the adhesive to peel.

Description

[Detailed Description of the Invention] Production 1 "Bori Ri Kitaka - This invention is a method for printing paper by repeating electrophotographic processes such as charging, optical writing, development, and transfer in printers, copiers, facsimile machines, etc. that use lasers. Applicable to electrophotographic devices that perform recording. Specifically, in such an electrophotographic apparatus, the present invention can be applied to an optical writing means that forms an image of light such as a laser beam on a photoreceptor through a lens and writes on the surface of the photoreceptor. More specifically, the present invention relates to a lens holding structure for holding a lens within a housing of the optical writing means.

Conventionally, especially when holding a long lens of an optical writing means, as shown in FIGS. A plurality of lens holding parts 3 are provided to protrude, and a lens 4 is placed on the mounting part 2,
A lens 4 was attached to a lens holding part 3 via an adhesive 5. Furthermore, the housing 1 is provided with a positioning part 6 that sandwiches the lens mounting part 2 and the lens holding part 3 and protrudes one step higher than them. Its longitudinal positioning is shown.

However, the lens 4 is generally made of organic glass with a relatively high coefficient of thermal expansion, while the housing 1 including the lens holding part 3 is made of metal such as aluminum die-casting with a low coefficient of thermal expansion. They are made of resin containing inorganic glass, and there is a large difference in the coefficient of thermal expansion between the two. Therefore, in the conventional lens holding structure as described above, first, in order to increase the adhesive strength as a whole, a plurality of locations where the lens is bonded by the lens holder 3 are provided, so thermal stress is generated at the bonding locations due to the difference in thermal expansion. The thermal stress causes a difference in the elongation of the lens 4 and the elongation of the lens holding portion 3 in the longitudinal direction, which causes problems such as the adhesive 5 peeling off. Further, there is also a problem in that the lens 4, which has relatively low rigidity, is distorted between the positioning portions 6 due to the difference in thermal expansion coefficient.

Therefore, the purpose of this invention is to securely position and hold the lens without causing distortion or peeling of the adhesive due to the difference in thermal expansion coefficient between the lens and the housing even if the long lens expands. It is in.

Therefore, in the lens holding structure of the present invention, as shown in the illustrated embodiment below, light such as a laser beam is emitted from a light source within the housing 40 and is deflected by the deflector 33, for example, f-θ. In an optical writing means 17 of an electrophotographic apparatus that forms an image on a photoreceptor 15 through a long lens such as a lens 34 and writes on the surface of the photoreceptor 15, a recess 34a is provided at the center in the longitudinal direction of the lens. , a lens holding portion 40a and the lens holding portion 40 are provided in the housing 40.
and a lens mounting portion 40b sandwiching the lens a.

The lens is attached to the lens holding portion 40a in its concave portion 34a.
The lens is attached via an adhesive 41, and the lens is placed on the lens mounting portion 40b.

Even if the lens expands, the lens is held in a state where it can freely expand and contract at both ends.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 8 is a laser printer equipped with a lens holding structure according to the present invention, and shows the overall schematic structure of its internal mechanism. The reference numeral 10 in the figure is the main body of the printer. Printer main body 10
1, a paper feed tray 1 is removably loaded on the right side in FIG. Paper 12 is stored in the paper feed tray 11. Then, the paper 12 is sent out by a paper feed roller 13, once stopped by a pair of registration rollers 14, and then sent out toward the photoreceptor 15 as the photoreceptor 15, which is an image carrier, rotates.

The photoreceptor 15 is rotated clockwise by a drive device (not shown), and its surface is charged by the charger 16 at this time. Thereafter, a laser beam is irradiated from the optical writing means 17 to form an electrostatic latent image on the photoreceptor 15.

The latent image is formed by a developing device 1 disposed on one side of the photoreceptor 15.
When passing through 18.

Visualize with toner. This visible image is transferred by the transfer charger 19 onto the paper 12 that has been conveyed as described above. After that, the fixing device! established at 20,
The paper is discharged through the paper conveyance path 21 to the paper discharge section 22 .

On the other hand, a cleaning unit 2 is provided on the other side of the photoreceptor 15.
3, the cleaning blade 24 removes residual toner on the photoreceptor 15 after the visible image has been transferred, and the charge removal brush 25 removes static electricity from the surface of the photoreceptor 15. Photoreceptor 15
The toner removed from the toner is sent to a collection toner tank 27 by a collection roller 26 and collected there.

By the way, in the optical writing means 17, specifically, as shown in FIG. The light is incident on the mirror surface of a rotating polygon mirror (deflector) 33 that rotates at a constant high speed.

The reflected light is deflected within a predetermined angular range for each surface by rotating the mirror surface, and repeatedly scans the same angular range. This laser light passes through a long f-theta lens 34 so as to form an image in a straight line at a constant speed on the surface of the photoreceptor 15, is reflected in a predetermined direction by a mirror 35, and is reflected in a second direction.
An image is formed on the photoreceptor 15 through a cylindrical lens, that is, a similarly long cylindrical lens 36 for correcting optical path deviation. The cylindrical lens 36 is for correcting optical path deviation caused by tilting of each mirror surface of the deflector 33.

Now, such optical writing means 17 is housed in a box-shaped housing 40, as shown in FIG. The housing 40 is made of a material with a relatively low coefficient of thermal expansion, such as metal such as aluminum die-casting or resin containing glass. As shown in FIG. 1, the housing 40 is provided with a lens holding portion 40a projecting upward. Lens holding part 4
0a has a cylindrical shape. And this lens holding part 40
A pair of lens mounting portions 40b are provided which protrude to the same height as the lens holding portions 40b, which are sandwiched between the lens mounting portions 40a and 40b. Furthermore, those lens holding parts 4
A pair of positioning parts 40c are provided which sandwich the lens mounting part 40a and the lens mounting part 40b and protrude higher than them.

On the other hand, the elongated f-theta lens 34 described above is made of plastic, and as shown in FIG. 1, is provided with a cylindrical recess 34a at its longitudinal center. The diameter dimension a of this recessed portion 34 is made slightly larger than that of the lens holding portion 40a.

Then, the concave portion 34a of the f-θ lens 34 is butted against the lens holding portion 40a, and the f-θ lens 34 is attached to the lens holding portion 40a via the adhesive 41. f-
Both ends of the θ lens 34 are placed on the lens mounting portion 40b. Further, one positioning portion 40c holds both end surfaces of the f-θ lens 34 to position it in the longitudinal direction.

According to this illustrated embodiment, as shown in FIG.
As a result, the bonding strength can be increased and the bonding location can be reduced to only one location on the lens holding portion 40a.

Moreover, both ends of the f-θ lens 34 are placed on the lens mounting portion 40.
Since the f-θ lens 34 is placed on the housing 40 and can expand and contract freely, even if the f-θ lens 34 expands, the influence of thermal stress due to the difference in thermal expansion coefficient with the housing 40 is reduced.

By the way, in the illustrated embodiment described above, the f-θ lens 34
is positioned in the longitudinal direction by the positioning portion 40c. but,
For example, as shown in FIGS. 2 and 3, the recess 34a of the f-theta lens 34 is formed in two stages, and a fitting hole 50 with a smaller diameter is provided in the center, while the upper end of the lens holding part 40a is 5 protrusions are provided in the center, and the protrusions 51 are inserted into the fitting holes 50.
By fitting with the f-theta lens 34, the movement of the f-theta lens 34 in the longitudinal direction can be restricted and the f-theta lens can be positioned in that direction. Further, as shown in FIG. 4, a downward protrusion 52 is provided at the center of the recess 34a of the f-θ lens 34, and a fitting hole 53 is provided at the center of the lens holding portion 40a, and the protrusion 52 is inserted into the fitting hole. 53, it is also possible to similarly position the f-theta lens 34 in its longitudinal direction.

Therefore, according to these other embodiments, the positioning section is unnecessary and there is no member for regulating both ends of the f-theta lens 34, so the f-theta lens 34 can be expanded and contracted more freely at both ends. It can be kept in the same condition. Furthermore, since the positioning part 40c is not provided, it is possible to eliminate the trouble of removing each gate part 54 for making the flow direction constant in the mold during the lens manufacturing process, as shown in FIG.

In addition, in the illustrated embodiment described above, as a long lens, f
-The configuration is such that the θ lens 34 is used and held; however,
If the lens is long, it may be configured to hold not only the f-θ lens but also other lenses.

Therefore, according to the present invention, a concave portion is provided in the center in the longitudinal direction of a long lens, and the lens is attached to the lens holding portion through an adhesive in the concave portion, so that even if the lens expands, However, the effect of the difference in thermal expansion coefficient with the housing is small, causing distortion in the lens,
The lens can be held securely without the adhesive peeling off.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a lens holding structure of an optical writing means according to an embodiment of the present invention, and FIG. 2 is another embodiment of the lens holding structure, of which (a) FIG. 4 is a partial cross-sectional view showing how the lens is attached; FIG. The figure shows a third embodiment of the lens holding structure.
5 is a perspective view showing an overview of the optical writing means of a laser printer to which the present invention is applied; FIG. 6 is a schematic configuration diagram showing the internal mechanism of the laser printer; FIG. 7 is a partial sectional view similar to the figure; 8 is a sectional view showing a lens holding structure of a conventional optical writing means, and FIG. 8 is a schematic perspective view thereof. L...Laser light! (light) 15...
. . . Photoreceptor 17 . . . Optical writing means 33 . . . Deflector 34 . . . f-θ lens (lens) 34a
......Concavity 40...Housing 40a...Lens holding part 40b...
・・・・・・Lens mounting part 41・・・・・・Adhesive Patent Attorney Nakao Co., Ltd. Figure 1 Figure 2 Figure 4 Figure 0 2325 1519 4 Old

Claims (1)

[Claims] In an optical writing means of an electrophotographic apparatus, in which light is emitted from a light source within a housing, the light is deflected by a deflector, an image is formed on a photoreceptor through a long lens, and writing is performed on the surface of the photoreceptor. A recess is provided in the center of the direction, the housing is provided with a lens holding part and a lens mounting part sandwiching the lens holding part therebetween, the lens is attached to the lens holding part in the recess through an adhesive, and A lens holding structure for an optical writing means, in which both ends of the lens are placed on a lens placement part.