JP2560288B2 - Optical writing device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical writing device having a supporting means for preventing the warp of an imaging element.

(Prior Art) Recent advances in information processing technology have been remarkable,
Along with this, a high density, high speed, and high printing quality are required for a printing apparatus which is one type of output apparatus.
A laser beam printer (LBP) that uses a laser and a deflection modulator as an optical writing device or an OFT that uses an optical fiber tube as a printing device that satisfies these performances.
An electrophotographic printer using a printer has been put into practical use.

However, both the above LBP and OFT printer are very expensive, and the large size of the device itself is a major cause of the spread of the device. In order to solve these problems, LEDs that use a cylindrical lens array (hereinafter referred to as SELFOC lens) as an imaging lens facing the light emitting diode array as a small and medium-sized inexpensive printer
A printer and a liquid crystal light valve printer using a uniform light source, a liquid crystal shutter, an imaging lens, and the like have been proposed.

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

In the optical writing device using the combination of the light emitting diode array and the uniform light emitting source and the liquid crystal shutter as the light emitting means, when the light emitting diode array is used, the printing speed is increased, the power consumption is reduced, and the life of the element is extended. From the standpoint of the above, and in the case of using the combination of the uniform light emitting source and the liquid crystal shutter, from the viewpoint of downsizing of the optical writing device, the SELFOC lens having a high aperture angle is used.

The problems in the case of using a commercially available SELFOC lens will be described with reference to FIGS. 8 to 12.
A conventional SELFOC lens has an aperture angle of 20.
There are 9 °, 9 °, and 6 °, but the light utilization efficiency is about 1 / for a SELFOC lens with an aperture angle of 20 ° and a SELFOC lens with an aperture angle of 20 °, respectively.
It becomes 5 and 1/15. Further, as the aperture angle is made smaller, the conjugate length (TC) of the SELFOC lens 9 between the light emitting means 10 and the photoconductor 3 becomes longer, so that the optical writing device becomes larger. On the other hand, when a SELFOC lens having a high aperture angle is used, there is a problem that the depth of focus is shallow.

Regarding the defocus of the SELFOC lens, as shown in FIG. 9, it is considered to be divided into three types, that is, (a) one side deviation, (b) both sides deviation, and (c) center deviation.
As shown in the figure, the decrease in MTF due to the center deviation in (c) is the largest. Regarding the SELFOC lens with an aperture angle of 20 °,
The permissible range of the center deviation is within a very small range of 0.1 mm or less. Therefore, it is very important to suppress the occurrence of the center deviation when attaching the SELFOC lens.

11 and 12 show a conventional example in which a SELFOC lens is attached to an optical writing device using a light emitting diode array as a light emitting means. In FIG. 11, the center lines of the light emitting means 10 and the SELFOC lens 12 are adjusted by the SELFOC support block 11. However, since a tightening force is applied upward by tightening at both ends of the SELFOC lens fixing portion, a downward warp is likely to occur at the center of the SELFOC lens. Therefore, the image by the printer using the optical writing device by the fixing method shown in the conventional example is
Defocusing often occurred in the center of the image.

Conventionally, several methods for preventing the warp of the SELFOC lens as described above have been proposed. For example,
In the 56-16160 publication, it is proposed to provide a plurality of twist adjusting screws and deflection adjusting screws in the longitudinal direction of the SELFOC lens, and in the existing liquid crystal light valve, the SELFOC lens is attached to a metal plate. Is also known.

(Problems to be solved by the invention) However, in the case where a plurality of adjustment points are provided in the SELFOC longitudinal direction, in the case of a SELFOC lens having an aperture angle of 20 °, the distance from the SELFOC plane to the focal plane is as short as about 5 mm. Therefore, it is difficult to provide a complicated adjustment mechanism,
Adjustment work is also required. In addition, a SELFOC lens adhered to a metal plate with an adhesive is difficult to adhere with an accuracy of 0.1 mm, which is not practical.
The present invention has been made in view of the problems of the conventional techniques as described above. Therefore, the present invention relates to holding a SELFOC lens in an optical writing device, and an object of the present invention is to provide a high-resolution optical writing device that prevents warping of the SELFOC lens.

Another object of the present invention is to provide an optical writing device which is easy and inexpensive to assemble, is lightweight, and is small in size.

(Means for Solving the Problems) The above object of the present invention is to provide optical writing having a light emitting means that can be modulated according to an image signal and an imaging element for projecting an optical image of the light emitting means onto a photoconductor. In the apparatus, the distance between the image forming element and the light emitting means is maintained at a predetermined length, and an image forming element supporting member that movably supports at least one of both ends of the image forming element is provided.

In the present invention, liquid crystal micro-shutter arrays, uniform light emitting light sources, fluorescent display array, and the like are included as the light emitting means that can be modulated according to image information, in addition to the LED allen.

In the invention of the present application, the following cases may be mentioned as examples of movably supporting at least one of both ends of the imaging element.

(1) The imaging element support member is provided with a rotating body rotatable in the longitudinal direction of the imaging element, and the rotating body supports one end or both ends of the imaging element. More specifically, the imaging element support member that movably supports at least one of both ends of the imaging element has a rotating body that can rotate along the longitudinal direction of the imaging element, and the imaging element is supported by the rotating body. One or both ends of the child are supported.

(2) One end of the image forming element is rotatably attached to the image forming element supporting member and the other end is attached so as to be movable in the longitudinal direction of the image forming element. More specifically, an imaging element support member that movably supports at least one of both ends of the imaging element is provided,
(A) A circular hole into which the imaging element support member inserts a pin that rotatably supports one end of the imaging element, and a length that supports the other end of the imaging element support member so that the pin is slidable in the longitudinal direction of the imaging element. And a structure in which pins provided at both ends of the imaging element are supported by penetrating the round hole and the elongated hole, and (b) the imaging element support member is an imaging element. Has a pin for rotatably supporting one end of the imaging element and a pin for slidably supporting the other end in the longitudinal direction of the imaging element. It has a structure that is supported by penetrating the pin in the provided long hole.

(Operation) The operation of the present invention will be described with reference to FIG.

Since both ends of the SELFOC lens 12 are attached to the imaging element support body for adjusting the distance between the SELFOC lens and the light emitting means on the substrate 9 via the rotatable supporting device 14, the SELFOC lens Even if both ends of the SELFOC lens are fixed, the stress applied to the SELFOC lens is absorbed by the movement of the fixed portion at the SELFOC lens end, and no distortion occurs at the center of the SELFOC lens.

At this time, if an elastic body is provided on the imaging element support and tension is applied from the center portion of the SELFOC lens toward both ends (in the direction of the arrow in FIG. 1), the above-mentioned warp prevention effect is enhanced.

(Examples) The present invention will be described in more detail with reference to Examples.

2 and 3 show an embodiment of the present invention, in which a light emitting diode array is used as the light emitting means 10, and a SELFOC lens 12 is used as the imaging element. The image forming element indicating member includes a position adjusting roller 17 and a fixed roller.
Support frame 15 and moving frame 16 with 18 attached
Consists of. The SELFOC lens 12 is movably supported by these rollers, but the SELFOC lens and the light emitting diode array are provided by applying a metal position adjusting roller 17 to the notched portion accurately cut with respect to the center line. Are positioned so that the distance between them becomes a predetermined length.

The contact of the position adjustment roller 17 to the selfoc lens notch and the downward support of the selfoc lens are
By the fixed roller 18 provided at intervals of the selfoc notch. The fixed roller 18 is a metal roll covered with an elastic material such as rubber, and the SELFOC lens is sufficiently fixed in the vertical direction.

A coil spring 19 is attached between the moving frame 16 and the SELFOC lens 12, and tension is applied to the SELFOC lens via this coil spring. When the tension is applied via the coil spring, the tension is easy to adjust because the tensile force is proportional to the changed position.

The procedure for actually mounting the SELFOC lens is shown below. First, after inserting the notches at both ends of the SELFOC lens between the position adjusting roller 17 and the fixed roller 18, the support frame 15 is fixed to the substrate 9. After attaching one end of the coil spring to the SELFOC lens, the moving frame 16 with the other end of the coil spring is attached to the support frame via the tension adjusting screw 20. The tension adjusting screw is composed of a combination of a pushing screw 201 and a pulling screw 202, and by changing the distance between the support frame 15 and the moving frame 16, the tension of the selfoc lens by the coil spring can be adjusted.

FIG. 4 shows another embodiment of the present invention. An end of the SELFOC lens 12 is movably supported by a fixed roller 18 and a one-point fixed support block 21 having a triangular prism-shaped convex portion. In this embodiment, since the contact area between the one-point fixed support block and the SELFOC lens cutout is small, the freedom in the longitudinal direction of the SELFOC lens is not impaired, and the structure is simple and the processing is easy.

FIG. 5 shows still another embodiment of the present invention. A support block 23 having a long hole extending in the longitudinal direction of the SELFOC lens 12 is fixedly provided on one side of the substrate 9, and a support block 24 having a round hole is fixedly provided on the other side. A sliding pin 25 is attached to one end of the SELFOC lens, and a fixed pin 26 is attached to the other end of the SELFOC lens. The former is a long hole of the support block 23, and the latter is a circle of the support block 24. The SELFOC lenses are respectively fitted into the holes, so that one end of the SELFOC lens is slidably supported and the other end is rotatably supported.

FIG. 6 shows an embodiment of the present invention in which the relationship between the SELFOC lens and the support block is opposite to that of the embodiment of FIG. That is, a long hole is provided at one end of the SELFOC lens 12 and a round hole is provided at the other end of the SELFOC lens 12, and pins attached to support members 25 and 26 fixedly provided on the substrate 9 are provided. 27 and 28 penetrate the long hole and the round hole. Also in the case of this embodiment, as in the embodiment of FIG. 5, the SELFOC lens is rotatable on one mounting portion and movable on the other side in the longitudinal direction. No stress is applied.

(Effect of the Invention) In the present invention, since the coupling element supporting member that movably supports at least one of both ends of the imaging element is provided, the end of the imaging element moves to the imaging element supporting member. Supported as possible. Therefore, when fixing the imaging element, the imaging element does not warp. Even after the image-forming element is attached, even if the image-forming element linearly expands due to environmental changes (such as temperature change), the end of the image-forming element can move, so that the stress is absorbed and warpage is prevented. It never happens. Therefore, image blurring over the entire print image and density unevenness of fine lines due to latent image blurring do not occur.

Further, there is also an advantage that individual adjustment is not necessary, as compared with a supporting device in which a plurality of adjusting mechanisms are provided in the longitudinal direction.

[Brief description of drawings]

FIG. 1 is an explanatory view for explaining the operation of the present invention, and FIG.
FIG. 3 is a schematic vertical sectional view of an essential part of an embodiment of the present invention, FIG. 3 is a sectional view taken along the line NN of FIG. 2, and FIG. 4 is an outline of an essential part of another embodiment of the present invention. FIG. 5 is a longitudinal sectional view, FIG. 5 and FIG. 6 are explanatory views showing the attachment state of the SELFOC lens in this embodiment, and FIG. 7 is a schematic configuration of an electrophotographic printer using an optical writing device. Explanatory drawing, FIG. 8 is an explanatory view for explaining the optical properties of the SELFOC lens, FIG. 9 is an explanatory view showing the state of SELFOC lens displacement, and FIG. 10 is a SELOC lens displacement. 11 is a graph showing the state of the depth of focus with respect to FIG. 11, FIG. 11 is an explanatory diagram for explaining the attachment state of the conventional SELFOC lens, and FIG. 12 is a sectional view taken along the line MM ′ of FIG. 1 ... Photoconductor, 2 ... Charge corotron, 3 ... Optical writing device, 4 ... Developing device, 5 ... Transfer corotron, 6
...... Fixer, 7 …… Cleaning device, 8 …… Recording paper,
9 ... Substrate, 10 ... Light emitting means, 11 ... Support block, 12
…… Selfoc lens, 13 …… Protective cover, 14 …… Support device, 15 …… Support frame, 16 …… Moving frame, 17
…… Position adjusting roller, 18 …… Fixed roller, 19 …… Coil spring, 20 …… Tension adjusting screw, 201 …… Pushing screw, 202
…… Drawing screw, 21 …… One-point fixed support block, 23,24…
… Support block, 25 …… Sliding pin, 26 …… Fixed pin, 2
7, 28 ... pin.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical display location G02B 7/00 (72) Inventor Ryoichi Hirano 2274 Hongo, Ebina City Fuji Xerox Co., Ltd. Ebina Works (72 ) Inventor Toshiro Yamamoto 2274 Hongo, Ebina City, Fuji Xerox Co., Ltd.Ebina Business Office (72) Inventor Toru Okamoto 2274 Hongo, Ebina City, Ebina Business Office Fuji Xerox Co., Ltd. (56) Reference JP-A-56-16160 (JP, JP-16-16160) A) JP 61-46918 (JP, A) JP 58-178306 (JP, A) JP 58-87508 (JP, A)

Claims (3)

(57) [Claims] 1. An optical writing device having a light emitting means capable of being modulated according to an image signal and an image forming element for projecting an optical image of the light emitting means onto a photoconductor, and a gap between the image forming element and the light emitting means. Is kept at a predetermined length, and at least one of both ends of the image forming element is movably supported by the image forming element supporting member having a rotatable body along the longitudinal direction of the image forming element. An optical writing device, wherein one end or both ends of an imaging element are supported by a body. 2. An optical writing device having a light emitting means capable of being modulated according to an image signal and an image forming element for projecting an optical image of the light emitting means onto a photoconductor, wherein a gap between the image forming element and the light emitting means. Is provided with a predetermined length, and at least one of both ends of the imaging element is movably supported, and the imaging element support member allows one end of the imaging element to rotate. A round hole for inserting a supporting pin and an elongated hole at the other end for slidably supporting the pin in the longitudinal direction of the imaging element are provided, and the pins provided at both ends of the imaging element are An optical writing device, which is supported by penetrating a round hole and an elongated hole. 3. An optical writing device having a light emitting means capable of being modulated according to an image signal and an image forming element for projecting an optical image of the light emitting means onto a photoconductor, and a gap between the image forming element and the light emitting means. Is provided with a predetermined length, and at least one of both ends of the imaging element is movably supported, and the imaging element support member allows one end of the imaging element to rotate. A pin for supporting and a pin for slidably supporting the other end in the longitudinal direction of the imaging element, and a round hole provided at one end of the imaging element and an elongated hole provided at the other end. An optical writing device, which is supported by penetrating the pin.