JPS62231969A - Optical writing device - Google Patents

Abstract

PURPOSE:To eliminate an out-of-focus image caused by a focus deviation, by fixing an image forming element to a supporting member provided in the longitudinal direction extending over the whole side face, so that they contact each other extending over the whole side face. CONSTITUTION:A groove-shaped recessed part 19 is formed to length being equal to a selfoc lens length of a selfoc lens 12, and also so that 24 of the selfoc lens always comes to the same position, even in case of a different selfoc lens length. The selfoc lens 12 is inserted into this groove-shaped recessed part and fixed. A supporting member is assembled so as to contact to an LED array by a selfoc lens fitting reference surface 20 on an LED array substrate 10, and an assembled LED array head is fixed to a frame 9 through an LED supporting member 14 so that a distance between an LED light emitting part 11 and a photosensitive body becomes a conjugate length of the selfoc lens.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an optical writing device characterized by means for mounting an imaging element.

BACKGROUND OF THE INVENTION Recent advances in information processing technology have been remarkable, and as a result, printing devices, which are one type of output device, are required to have high density, high speed, and even high print quality. Printing devices that satisfy these performances include a laser beam printer (LBP) that uses a laser and a deflection modulation device as an optical writing device, or an electrophotographic printer that uses an OFT printer that uses an optical fiber tube. It has been put into practical use.

However, both the above-mentioned LBP and OFT printers are very expensive and the devices themselves are large, which is a major factor preventing their widespread use. In order to solve these problems, a light-emitting diode array and a cylindrical lens array (hereinafter referred to as a bulb printer) as an imaging lens opposing each light-emitting diode array have been proposed as a small to medium-sized and inexpensive (111i) printer.

FIG. 10 shows the configuration of an electrophotographic printer using the above optical writing device. In this electrophotographic printer, a photoreceptor 1 is charged to a desired polarity by a charge corotron 2. Next, the light emitting means of the optical writing device 3 is caused to selectively emit light based on the image signal, and the light is focused on the photoreceptor 1 by the SELFOC lens to form an electrostatic latent image. Thereafter, toner is applied to this electrostatic latent image by the developing device 4, and then this toner is applied to the transfer plate.
The image is transferred onto a recording paper 8 by a tron 5 and fixed by a fixing device 6. The photoreceptor is cleaned by a cleaning device 7 for the next operation.

By the way, a conventional optical writing device used in the above electrophotographic printer has a structure shown in FIGS. 11 to 14, for example.

By the way, to explain the problems when using a commercially available SELFOC lens using FIGS. 7 to 9, the conventional SELFOC lens has the following problems:
There are lenses with aperture angles of 20', 9°, and 6°, but their light utilization efficiency is approximately 115 and 1, respectively, based on a SELFOC lens with an aperture angle of 20° and 9°, and 6°, respectively.
/15. Furthermore, as the aperture angle becomes lower, the conjugate length (TC) of the SELFOC lens becomes longer, resulting in the problem that the optical writing device becomes larger.

On the other hand, when using a SELFOC lens with a high aperture angle, there is a problem that the depth of focus is shallow.

Regarding the focus deviation of the SELFOC lens, as shown in Fig. 8, (a> one side deviation, (b) both sides deviation, and (C)
There are three types of center deviation (C), as shown in Figure 9, which causes the largest decrease in depth of focus due to center deviation.For a Selfoc lens with an aperture angle of 20', this center deviation The permissible range of Q is within a very small range of 1 mm or less. Therefore, it is very important to suppress this center shift when installing the SELFOC lens.

In actual optical printers, the factors that affect image blur and the accuracy of SELFOC lens installation include reference surface tolerances, torsion of the photoreceptor surface, and other factors that sometimes occur when SELFOC lens installation occurs. There is a problem with the SELFOC lenses warping.

The warpage caused by attaching the SELFOC lens will be explained. 11 to 14 are for explaining the mounting state of the SELFOC lens in a conventional optical writing device. In FIG. 11, 101. This is an ILED array substrate, and is attached to the frame 9 by an LED array head support member 14. The SELFOC lens 12 has a notch at the end that serves as the SELFOC lens attachment surface 5, which is closely connected to the SELFOC lens support member 13 attached to the LED array board, and is used for fixing the SELFOC lens. By tightening the SELFOC lens support member 13 with the SELFOC lens 12 in between with the screws 16, or as shown in FIGS. 13 and 14, the SELFOC lens support member 13, the positioning member 24, and the fixing screw 26 and 27 to fix the SELFOC lens.

Note that the reason why the reference plane is set 8 times apart when installing the SELFOC lens is as follows.

In general, the refractive index of the glass in Selfoc lenses varies depending on each lot, and in order to make them equal conjugate lengths (TC>), the Selfoc lens length (20) is cut in such a way that the TC is the same. So,
To position and assemble the centers of lenses with different shapes, as shown in Figure 12, make a notch at both ends of the part at a certain distance (a) from the center of the self-locking lens. To attach the lens, a reference surface 15 is provided, and this surface is installed on the Selfoc lens support member having a height TC-a. Therefore, the SELFOC lens length (
Even if the ZO) is different, the center of the SELFOC lens is L.
It comes to the position TC/2 from the ED light emitting part.

Problems to be Solved by the Invention However, when the SELFOC lens is supported by the above fixing means, the SELFOC lens is supported only by the portion that is in contact with the SELFOC lens mounting table surface 15 and the support member. Therefore, the SELFOC lens may be significantly warped depending on the way the SELFOC lens fixing screw is applied. Especially for 5AL-20, which has a short SELFOC lens length (20), it is 0.2 m.
A warpage of about m is likely to occur, and as is clear from the above description, the magnitude of the warp exceeds the permissible range for image blurring.

The present invention has been made with the object of solving the above-mentioned problems in conventional optical dedication devices.

Means for Solving the Problems The above object of the present invention is to provide an optical writing device comprising a light emitting means that can be modulated in accordance with image information and an imaging element for projecting an optical image of the light emitting means onto a photoreceptor. This is achieved by fixing at least one side surface of the imaging element to a support member arranged in the longitudinal direction of the imaging element in a state in which the entire side surface of the imaging element is in contact with the support member.

In the present invention, as a mode for fixing the imaging element in a state in which it is in contact with the supporting member over the entire side surface of the imaging element, the supporting RIS material disposed in the longitudinal direction of the imaging element is provided with a In some cases, a groove-like recess is formed, and the imaging element is inserted and fixed therein. Further, the imaging element may be fixed by a groove-shaped recess formed by a plurality of support members. Note that the groove-shaped recess needs to be provided at a position TC/2 from the center of the imaging element or the light emitting part of the light emitting means.

Another method for fixing is to use an adhesive. That is, the imaging element is fixed to a support member disposed in the longitudinal direction over the entire side surface of the imaging element using an adhesive. In that case, at least one of the surface of the support member and the surface of the imaging cord to be bonded needs to be roughened and roughened.

Function In the present invention, since at least one side of the imaging element is fixed in contact with the support member disposed in the longitudinal direction over the entire side surface of the imaging element, the imaging element There is no warpage in the center of the element, and therefore, once the imaging element is placed at a predetermined position on the support member, there is no center shift due to warpage of the imaging element.

Example Hereinafter, the present defense will be explained with reference to examples.

1 and 2 show one embodiment of the present invention.

The optical writing device includes an LED array substrate 10. LED array light emitting section 11 light emitting layer 11 provided on the LED array substrate
It consists of a selfoc lens 12, both left and right support members 18 for supporting the selfoc lens, and a fin 17 provided on the other surface of the LED array board. A groove-like recess 19 for supporting the SELFOC lens is formed in the support member 18 . This groove-like recess 19 has a length equal to the Selfoc lens length ZO of the Selfoc lens 12,
Moreover, even if the SELFOC lenses have different lengths, the SELFOC lenses 24 are formed so that they are always at the same position. The SELFOC lens 12 is inserted into this groove-like recess and fixed. The support member is an LED array ticket board 10
The upper SELFOC lens is attached to the reference surface 20 and assembled so as to be in close contact with the ED array. is fixed to the frame 9 so that the selfoc lens has a co-j9 length (TC).

FIG. 3 is a cross-sectional view of another embodiment of the invention. In the optical writing device of this embodiment, a groove-shaped recess 19 is formed only in one of the pair of left and right support members 18.21.
is formed.

FIG. 4 is a cross-sectional view of yet another embodiment of the invention.

In this embodiment, the support member of the SELFOC lens is separated into two upper and lower parts 22 and 23, and the groove-like recess is formed by fixing these support members with fixing screws 25. The SELFOC lens is inserted and fixed in the groove-shaped recess formed by these two support members.

FIG. 5 and FIG. 6 show an embodiment in which a SELFOC lens is fixed with an adhesion agent in accordance with the present invention. In this embodiment, one side of the Selfoc lens is fixed with an adhesive to a support member 21 disposed in the longitudinal direction of the Selfoc lens, and both ends of the Selfoc lens are fixed to a support member 21 disposed in the longitudinal direction of the Selfoc lens. Support member 13
It is fixed to the LED array board 10 using fixing screws 26 and 27. In this embodiment, at least one of the surface to which the SELFOC lens is bonded and the surface to which the support member is bonded needs to be roughened, thereby improving the bonding strength. In the above embodiment, only one side of the SELFOC lens is attached to the support member, but it may be configured to be sandwiched between the support members from both sides.

Effects of the Invention As described above, in the optical writing device of the present invention, at least one side of the imaging element includes a support member disposed longitudinally over the entire side surface thereof, and a support member disposed over the entire side surface of the imaging element. Since the image forming element is fixed in a contact state, there is no possibility of warping in the center of the image forming element. Therefore, once the image forming element is placed in a predetermined position on the support member, The effect is that center shift due to warpage is eliminated, and image blur due to focus shift is eliminated.

[Brief explanation of drawings]

1 and 2 are a cross-sectional view and a vertical cross-sectional view of a main part of an embodiment of the present invention, and FIGS. 3 and 4 are a cross-sectional view and a fifth embodiment of another embodiment of the present invention, respectively. The figure is a cross-sectional view of the main part of the embodiment of the invention, FIG. 6 is an explanatory diagram showing the installation state of the Selfoc lens in the embodiment of FIG.
8 and 8 are explanatory diagrams for explaining the optical properties of the SELFOC lens, FIG. 9 is a graph showing the state of decrease in MTF due to positional deviation, and FIG. 10 is an overview of the configuration of the optical printer. FIG. 11 is a schematic vertical sectional view of a conventional optical writing device. FIG. 12 is an explanatory diagram showing how the SELFOC lens is installed in the optical writing device of FIG. 11. FIG. 14 is a schematic cross-sectional view of another conventional marketing device, and FIG. 14 is an explanatory diagram showing how the SELFOC lens is installed in the optical writing device of FIG. 13. 1...Photoreceptor, 2...Charge corotron, 3...
- Optical writing device, 4... Developing device, 5... Transfer corotron, 6... Fixing device, 7... Cleaning device,
8... Recording paper, 9... Frame, 10... LED
Array substrate, 11... LED light emitting section, 12... SELFOC lens, 13... SELFOC lens support member, 14... LED array head support member, 15...
・For self-cleaning lens installation, use reference surface, 16...Selfoc lens fixing screw, 17...fin, 18.
... Support member, 19 ... Groove-shaped recess, 20 ... Reference surface, 21 ... Support member, 22 ... Upper support member, 23
. . . lower support member, 24 . . . positioning member, 25.
26 and 27...fixing screws. Figure 1 % 2 Figure S Figure 6 (a) One side deviation (D) Both sides deviation (C) Center deviation Figure 8 2! Displacement amount Atsushi 11 drawings 12 drawings

Claims (3)

[Claims] (1) In an optical writing device consisting of a light emitting means that can be modulated in accordance with image information and an imaging element for projecting an optical image of the light emitting means onto a photoreceptor, at least one side of the imaging element is What is claimed is: 1. An optical writing device characterized in that an image forming element is fixed to support members arranged in a direction such that the entire side surface of an imaging element is in contact with the support members. (2) The optical writing device according to claim 1, wherein the support member is a member having a recessed portion equal to the length of the imaging element in the optical axis direction. (3) The optical writing device according to claim 1, wherein the support member is a plate-like member parallel to the imaging element.