JP2002148542A - Optical writer and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a housing structure capable of making an optical writer more compact and the arrangement constitution of an optical system. SOLUTION: In the optical writer 5 provided with light sources, a light defector 62 for distributing light beams L1 to L4 from plural light sources into two symmetrical directions and deflecting these beams and an optical system for guiding plural light beams deflected and scanned by light deflectors symmetrically arranged in the two directions centering the deflector 62 to corresponding image carriers 1 to 4 to form images, a housing 50 has a base 50A on which the deflector 62 and the optical system are arranged and a frame-like sidewall 50B surrounding the periphery of the base 50A and consists of structure for vertically dividing the housing 50 by arranging the base 50A on the approximately center part of the sidewall 50B. Light sources are arranged on the sidewall 50B of the housing 50, the deflector 62 is arranged on the approximately center part of the base 50A and optical members 63 to 82 constituting the optical system are dividedly arranged on both faces of the base 50A.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical writing device for writing a latent image by irradiating a light beam onto a surface to be scanned of a plurality of image carriers arranged side by side, and a multi-function device including the optical writing device. The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile, and a plotter that forms a color image.

[0002]

2. Description of the Related Art Conventionally, light beams emitted from a plurality of light sources are applied to four image bearing members (for example, photosensitive drums) arranged side by side to write a latent image thereon, and each image bearing member is subjected to writing. After the latent images formed on the sheet are developed with respective developers of different colors (for example, yellow, magenta, cyan, and black toners) to be visualized, the transfer of a recording sheet or the like carried on a transfer conveyance belt or the like is performed. The material is sequentially conveyed to the transfer section of each image carrier, and the visible images of each color formed on each image carrier are superimposed and transferred on the transfer material, and then the image transferred on the transfer material is fixed. A tandem type color image forming apparatus that obtains a multicolor image by using a tandem type is known. In such a tandem type color image forming apparatus, a type in which a latent image is written on each image carrier separately by an optical writing device individually provided for each image carrier is conventionally known. An optical writing device using an optical deflector composed of a polygon mirror and a motor for driving the polygon mirror is relatively expensive. Providing an optical writing device individually for each image carrier is costly in terms of parts costs and manufacturing costs. There's a problem. In addition, a large installation space is required to install a plurality of optical writing devices each having an optical deflector corresponding to the number of image carriers, and thus there is a problem that the entire image forming apparatus becomes large.

In order to reduce the cost and size of the tandem type color image forming apparatus, an optical deflector is shared by a plurality of light sources as a means for performing optical writing on a plurality of image carriers. 2. Description of the Related Art There is known an optical writing apparatus that deflects and scans light beams from a plurality of light sources at the same time by an optical deflector and irradiates a plurality of image carriers with light to perform optical writing.

[0004]

As described above, in an optical writing apparatus for performing optical writing by simultaneously deflecting and scanning light beams from a plurality of light sources and irradiating a plurality of image carriers with one optical deflector. An optical system is arranged symmetrically in two directions about the optical deflector, and has an optical system for guiding a plurality of light beams deflected and scanned by the optical deflector onto the corresponding surfaces to be scanned, respectively, to form an image. Since the optical system is composed of a large number of optical members corresponding to a plurality of light beams, it may not be possible to achieve a compact optical writing device depending on the arrangement of these optical members. In view of the above, an object of the present invention is to provide an image forming apparatus provided with a compact optical writing device, with the object of proposing a housing structure and an arrangement configuration of an optical system capable of further reducing the size of the optical writing device. The purpose is to do.

[0005]

In order to achieve the above object, the present invention provides a plurality of light sources, an optical deflector for distributing and deflecting light beams from the plurality of light sources in two symmetrical directions, An optical system that is arranged symmetrically in the two directions with the deflector as a center and guides and forms a plurality of light beams deflected and scanned by the optical deflector on the corresponding surfaces to be scanned, a plurality of light sources; In an optical writing device in which an optical deflector and an optical system are housed in a single housing, the housing includes a base on which the optical deflector and the optical system are disposed, and a frame-shaped side wall surrounding the base. And a structure in which the base is provided at a substantially central portion of the side wall to partition the housing up and down, the plurality of light sources are disposed on the side wall of the housing, and the light deflector is disposed at a substantially central portion of the base. And constitute the optical system Undergraduate material is obtained by a structure which is disposed separately on both sides of the base (Claim 1).

Further, in the optical writing apparatus according to the present invention, in addition to the above configuration, the base and the side wall of the housing are integrally formed by resin molding, and the cross-sectional structure of the housing has a substantially H-shaped structure. (Claim 2). Further, in the optical writing device according to the present invention, in addition to the above configuration, the housing is formed of a resin material having a small difference in thermal expansion coefficient from a frame of the image forming apparatus main body to which the optical writing device is attached. Features (claim 3).

Further, according to the present invention, a plurality of image carriers arranged side by side, optical writing means for writing a latent image by irradiating a light beam onto a scanned surface of the plurality of image carriers, Developing means for developing the latent image formed on the body with a developer of a different color to make it a visible image, and sequentially transporting the transfer material to the position of each image carrier, and developing each of the colors formed on each image carrier. 4. An image forming apparatus comprising: means for superimposing and transferring a visible image on a transfer material; and means for fixing an image transferred on the transfer material, wherein the optical writing means is used as the optical writing means. An optical writing device according to any one of the above is provided (claim 4).

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The construction, operation and operation of an optical writing apparatus and an image forming apparatus according to the present invention will be described below in detail based on the illustrated embodiment. FIG. 1 is a sectional view of an optical writing apparatus showing one embodiment of the present invention, FIG. 2 is a schematic configuration diagram showing an example of an image forming apparatus provided with the optical writing apparatus shown in FIG. FIG. 2 is a plan view showing a configuration of a top surface side of a substrate of the optical writing device shown in FIG. 1. FIG. 1 shows a cross-sectional configuration taken along the line AA ′ of FIG. FIG. 4 is a sectional view showing the structure of the housing of the optical writing device shown in FIG. 1. FIG. 5 is a diagram showing the arrangement of the optical writing device shown in FIG. FIG.
FIG. 3 shows the arrangement of the light source unit, the optical deflector, and the optical system extracted from the configuration shown in FIG.

The image forming apparatus shown in FIG. 2 is a full-color image forming apparatus in which a plurality of drum-shaped photoconductive photosensitive members (hereinafter, photosensitive drums) 1, 2, 3, and 4 are arranged as a plurality of image carriers. And the four photosensitive drums 1, 2, 3,
4 is, for example, yellow (Y),
An image corresponding to each color of magenta (M), cyan (C), and black (Bk) is formed (the order of the colors is not limited to this and can be set arbitrarily). Around each of the four photosensitive drums 1, 2, 3, and 4,
A charging unit (a charging roller, a charging brush, a charging charger, etc.) for forming an image by an electrophotographic process;
7, 8, 9 and the light beams L1, L from the optical writing device 5.
2, L3, L4 exposure part and development part (Y, M, C, Bk
Transfer device 22 including transfer devices (transfer rollers, transfer brushes, etc.) 14, 15, 16, and 17 disposed on the transfer transfer belt 22 a and the back surface thereof. And cleaning units (cleaning blades, cleaning brushes, etc.) 18, 19, 2
0, 21 and the like are provided, and it is possible to form an image of each color on each of the photosensitive drums 1, 2, 3, and 4.

The optical writing device 5 has four photosensitive drums 1,
2, 3 and 4 are arranged diagonally above the image forming unit arranged side by side,
It is fixed to main body frames 29 and 30 of the image forming apparatus. This optical writing device 5 has four light source units 52, 53, 5 as shown in the configuration examples in FIGS.
4, 55, and light beams L1, L from each light source unit.
2, an optical deflector 62 for deflecting and scanning L2 and L4 in two symmetric directions, and a plurality of light deflectors 62 arranged symmetrically in the two directions with the optical deflector 62 as a center, Optical systems (imaging lenses 63, 64, 69,
70, 71, 72, mirrors 65, 6 for turning back the optical path
6,67,68,73,74,75,76,77,7
8, 79, 80 etc.).
These components are housed in one housing 50.

More specifically, the housing 50 includes a base 50A on which the optical deflector 62 and the optical system are disposed, and a base 50A.
A has a frame-shaped side wall 50B surrounding the periphery of A, and a base 50A is provided at a substantially central portion of the side wall 50B to partition the housing 50 up and down. The four light source units 52, 53, 54, 55 Side wall 50B of housing 50
And the optical deflector 62 is mounted on the base 50 of the housing 50.
An optical member (imaging lenses 63, 64, 69, 70, 71, 72,
Mirrors 65, 66, 67, 68, 7 for turning back the optical path
3, 74, 75, 76, 77, 78, 79, 80, etc.) are separately arranged on both surfaces (upper surface side and lower surface side) of the base 50A. Further, covers 87 and 88 are provided on the upper and lower portions of the housing 50, and an opening for passing a light beam is provided on the lower cover 87, and dustproof glasses 83, 84, 85 and 86 are provided in the openings. Is attached.
As shown in FIG. 4, the housing 50 includes a base 50A.
And the side wall 50B are integrally formed by resin molding, and the cross-sectional structure of the housing 50 has a substantially H-shaped structure. The housing 50 is provided on the frame 2 of the image forming apparatus main body to which the optical writing device 5 is attached.
It is formed of a resin material having a small difference in thermal expansion coefficient from that of the resin materials 9 and 30.

In the optical writing device 5, color-separated image data input from a document reading device (scanner) or an image data output device (personal computer, word processor, facsimile receiving unit, etc.) (not shown) is used for driving a light source. The light source (semiconductor laser (LD)) in each of the light source units 52, 53, 54, 55 is driven in accordance with the signal to emit a light beam. The light beams emitted from each of the light source units 52, 53, 54, 55 are converted into cylindrical lenses 56, 57,
After passing through 58 and 59, the light reaches a light deflector 62 directly or via mirrors 60 and 61, and is deflected and scanned in two symmetrical directions by two-stage polygon mirrors 62a and 62b rotated at a constant speed by a polygon motor 62c. . In the configurations shown in FIGS. 1 and 5, the polygon mirrors are used for the light beams L2 and L3,
Although the configuration is divided into two upper and lower stages for the L4 light beam, a configuration in which deflection scanning is performed by one thick polygon mirror may be employed.

The polygon mirrors 62a, 6 of the optical deflector 62
The light beams deflected and scanned in two directions by two beams in 2b respectively pass through first imaging lenses 63 and 64 composed of, for example, an upper-lower two-layer fθ lens and the like, and are returned to first folding mirrors 65 and 66, respectively. After being folded by 67 and 68 and passing through the opening of the base 51, the second imaging lenses 69, 70, 71, which are composed of, for example, a long toroidal lens, etc.
72, the second folding mirrors 73, 75, 77,
79, the third folding mirrors 74, 76, 78, 80, and dustproof glasses 83, 84, 85, 86 irradiate the surfaces of the photosensitive drums 1, 2, 3, and 4 for the respective colors to be scanned to form an electrostatic latent image. Write the image.

In the above-described optical writing device 5, the four light source units 52, 53, 54, 55 are composed of a semiconductor laser (LD) as a light source and a collimating lens for collimating the emitted light beam of the semiconductor laser. These are integrated into a holder, but two or more light source units for black (e.g., light source unit denoted by reference numeral 54) frequently used when forming a black-and-white image in order to enable high-speed writing. And a multi-beam configuration including a light source (LD) and a collimating lens. In the case of a multi-beam configuration, if the light source unit is configured to be rotatable around the optical axis with respect to the side wall 50B of the housing 50, the beam pitch in the sub-scanning direction can be adjusted,
Pixel density (for example, 600 dpi, 12
00 dpi).

Further, each of the light beams L1, L2, L3, L
In the optical path No. 4, a synchronization detecting mirror (not shown) for extracting a light beam at the scanning start position in the main scanning direction is provided. The light beam reflected by the synchronization detecting mirror is indicated by a broken line in FIG. Are received by the synchronization detectors 81 and 82, and a synchronization signal for starting scanning is output. Further, as shown in FIG. 5, skew adjustment stepping motors 92, 93, 94 are provided on the third folding mirrors 74, 76, 78 arranged in the optical paths of the light beams L1, L2, L3. , L1, with reference to the scanning line position of the light beam L1,
The displacement of the scanning line positions of the light beams L2 and L3 is corrected.

The scanning direction of the light beam deflected by the optical deflector 62 is the main scanning direction, which is the axial direction of each photosensitive drum. The direction orthogonal to the main scanning direction is the sub-scanning direction, which is the direction of rotation of the photoconductor drum (the direction of movement of the surface of the photoconductor drum), and the direction of conveyance of the transfer conveyance belt 22a described later. . That is, the width direction of the transfer conveyance belt 22a is the main scanning direction, and the conveyance direction is the sub-scanning direction.

As shown in FIG. 2, below the four photosensitive drums 1, 2, 3 and 4 arranged side by side, a transfer and transport belt 22a stretched over a driving roller and a plurality of driven rollers is disposed. And is conveyed by a driving roller in the direction indicated by the arrow in the figure. Further, a plurality of paper feed units 23 and 24 containing a transfer material such as recording paper are installed in a lower part of the main body of the image forming apparatus. The transfer material stored in the paper feed units 23 and 24 The paper is fed to the transfer / conveyance belt 22a via rollers, conveyance rollers, and registration rollers 25, and is carried and conveyed by the transfer / conveyance belt 22a.

Each of the photoconductors 1, 2, 2
Each of the latent images formed on the developing units 10, 11, 1 is
The toner images of the respective colors Y, M, C, and Bk are developed and developed with toners of the respective colors Y, M, C, and Bk. Transfer means 1
The transfer is carried out by superimposing on the transfer material carried on the transfer / conveying belt 22a by 4, 15, 16, 17 sequentially. Then, the transfer material on which the four color images are transferred is conveyed to a fixing unit 26, where the images are fixed by the fixing unit 26,
7, the paper is discharged onto the paper discharge tray 28.

The configuration and operation of the optical writing apparatus and the image forming apparatus according to the present invention have been described above. In the optical writing apparatus 5 according to the present invention, the housing 50 includes the optical deflector 62 and the optical system. A base 50A to be provided, and a frame-shaped side wall 50B surrounding the periphery of the base 50A, and the base 50A is provided at a substantially central portion of the side wall 50B to partition the housing 50 up and down. 52,5
The optical deflector 62 is disposed at a substantially central portion of the base 50A of the housing 50, and optical members (image forming lenses 63, 64, and 69) constituting the optical system. , 70, 71, 72, mirrors 65, 66, 67, 68, 73, 74, 7 for turning back the optical path.
5, 76, 77, 78, 79, 80, etc.) are arranged separately on both sides (upper surface side and lower surface side) of the base 50A, so that optical writing is performed while securing the entire optical path length of the optical system. Since the size of the housing 50 of the device is not more than half of the optical path length, the size of the optical writing device can be reduced.

Incidentally, as shown in FIG.
Has a base 50A and a side wall 50B integrally formed by resin molding.
The housing 5 has a mold structure.
In addition, the optical deflector 62 can be made compact, and the strength can be ensured, and the optical deflector 62 has a structure in which vibrations and the like are hardly generated, and optical characteristics can be maintained. Further, since the housing 50 is formed by resin integral molding, the weight can be reduced, and post-processing is not required, so that productivity is high and manufacturing cost can be suppressed. Further, since the housing 50 is formed of a resin material having a small difference in thermal expansion coefficient from the frames 29 and 30 of the image forming apparatus main body to which the optical writing apparatus 5 is attached, the housing 50 of the optical writing apparatus 5 is connected to the image forming apparatus. Body frames 29, 30
Even in the state of being fastened, distortion of the housing 50 due to temperature change hardly occurs, and the optical characteristics can be maintained.

Since the image forming apparatus having the structure shown in FIG. 2 has the compact optical writing device 5 having the structure shown in FIGS. 1 and 3 to 6, it is compared with the conventional tandem type color image forming apparatus. A smaller and less costly color image forming apparatus can be provided. As shown in FIG. 2, a color image can be obtained by installing an image forming unit in which four photoconductor drums 1, 2, 3, and 4 are arranged side by side, an optical writing device 5, and a transfer transport device 22 at an angle. Further miniaturization of the forming apparatus can be achieved.

[0022]

As described above, according to the present invention, there are provided a plurality of light sources, an optical deflector for distributing and deflecting light beams from the plurality of light sources in two symmetric directions, and A plurality of light sources, an optical deflector, and an optical system that guide and image a plurality of light beams deflected and scanned by the optical deflector on the corresponding surfaces to be scanned. In an optical writing device in which a system is housed in a single housing, the housing has a base on which the optical deflector and the optical system are disposed, and a frame-shaped side wall surrounding the periphery of the base. Is provided at a substantially central portion of the side wall to partition the housing up and down, the plurality of light sources are disposed on the side wall of the housing, the optical deflector is disposed at a substantially central portion of the base, and the optical system The optical member constituting the base is Since a structure arranged separately on both sides, it is possible to achieve compactness of the optical writing device while ensuring the optical path length of the entire optical system.

Further, in the optical writing apparatus according to the present invention, in addition to the above configuration, the base and the side wall of the housing are integrally formed by resin molding, and the sectional structure of the housing has a substantially H-shaped structure. With such a configuration, the housing can be made compact and the strength can be ensured, and a structure in which vibrations and the like due to rotation of the optical deflector are hardly generated, and the optical characteristics can be maintained. Also,
Since the housing is formed by integral molding of resin, the weight can be reduced, and post-processing is not required, so that productivity is high and manufacturing cost can be suppressed. Furthermore,
In the optical writing device according to the present invention, in addition to the above configuration, the housing is formed of a resin material having a small difference in thermal expansion coefficient from a frame of an image forming apparatus main body to which the optical writing device is attached. Therefore, even when the housing of the optical writing device is fastened to the frame of the main body of the image forming apparatus, distortion or the like of the housing due to temperature change hardly occurs,
Optical characteristics can be maintained.

Further, according to the present invention, a plurality of image carriers arranged side by side, an optical writing means for irradiating a light beam on a surface to be scanned of the plurality of image carriers to write a latent image, Developing means for developing the latent image formed on the body with a developer of a different color to make it a visible image, and sequentially transporting the transfer material to the position of each image carrier, and developing each of the colors formed on each image carrier. In an image forming apparatus provided with a unit for transferring a visible image by superimposing it on a transfer material and a unit for fixing an image transferred on the transfer material, the optical writing unit having the compact configuration described above is used as the optical writing unit. Since the image forming apparatus is provided with the mounting device, a small-sized and low-cost tandem-type color image forming apparatus can be provided.

[Brief description of the drawings]

FIG. 1 is a sectional view of an optical writing device showing one embodiment of the present invention.

FIG. 2 is a view showing one embodiment of the present invention, and is a schematic configuration diagram showing an example of an image forming apparatus provided with the optical writing device shown in FIG.

FIG. 3 is a plan view showing a configuration of a top surface side of a base of the optical writing device shown in FIG. 1;

FIG. 4 is a sectional view showing a structure of a housing of the optical writing device shown in FIG.

FIG. 5 is a schematic configuration diagram illustrating an arrangement configuration of an optical deflector and an optical system extracted from the configuration of the optical writing device illustrated in FIG. 1;

FIG. 6 is a schematic configuration diagram showing a light source unit, an optical deflector, and an optical system extracted from the configuration shown in FIG. 3 and showing an arrangement configuration thereof.

[Explanation of symbols]

1, 2, 3, 4: photosensitive drum (image carrier) 5: optical writing device 6, 7, 8, 9: charging unit 10, 11, 12, 13: developing unit (Y, M, C, Bk) 14, 15, 16, 17: transfer means 18, 19, 20, 21: cleaning unit 22: transfer / conveyance device 22a: transfer / conveyance belt 23, 24: paper feed unit 25: registration roller 26: fixing Unit 27: Discharge roller 28: Discharge tray 29, 30: Frame of image forming apparatus main body 50: Housing 50A: Base 50B: Side wall 52, 53, 54, 55: Light source unit 56, 57, 58, 59: Cylindrical lens 60, 61: mirror 62: optical deflector 62a, 62b: polygon mirror 62c: polygon motor 63, 64: first imaging lens 65, 66, 67, 68: first folding mirror 6 9, 70, 71, 72: second imaging lens 73, 75, 77, 79: second folding mirror 74, 76, 78, 80: third folding mirror 81, 82: synchronization detector 83, 84, 85, 86: dustproof glass 87, 88: cover

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) G03G 15/04 111 B41J 3/00 D 5C072 H04N 1/04 H04N 1/04 D 1/113 104A F-term (reference) 2C362 AA42 BA50 BA51 BA53 BA90 CA39 DA02 DA03 DA06 DA08 2H030 AA05 AB02 BB02 2H045 AA01 BA02 BA22 BA33 BA34 CA63 CB22 DA02 DA04 2H071 AA26 BA03 BA22 BA27 DA02 DA03 EA18 2H076 AB02 AB07 AB18 EA01 HA14 X03 A03 HA03

Claims (4)

[Claims] A plurality of light sources; an optical deflector for distributing and deflecting light beams from the plurality of light sources in two symmetrical directions; and symmetrically arranged in the two directions about the optical deflector, An optical system for guiding a plurality of light beams deflected and scanned by the optical deflector onto corresponding scanning target surfaces, and forming an image,
An optical writing device in which a plurality of light sources, an optical deflector, and an optical system are housed in one housing, wherein the housing has a base on which the optical deflector and the optical system are arranged, and a frame shape surrounding the base. And the base is provided substantially at the center of the side wall to partition the housing up and down. The plurality of light sources are arranged on the side wall of the housing, and the light deflector is substantially An optical writing device which is arranged at a central portion, and wherein optical members constituting the optical system are arranged separately on both sides of the substrate. 2. The optical writing device according to claim 1, wherein the base and the side wall of the housing are integrally formed by resin molding, and a cross-sectional structure of the housing has a substantially H-shaped structure. Optical writing device. 3. The optical writing device according to claim 2, wherein the housing is formed of a resin material having a small difference in thermal expansion coefficient from a frame of an image forming apparatus main body to which the optical writing device is attached. Optical writing device. 4. A plurality of image carriers arranged in parallel, optical writing means for writing a latent image by irradiating a light beam on a surface to be scanned of the plurality of image carriers, and forming on each image carrier. Developing means for developing the formed latent image with a developer of a different color to form a visible image, and sequentially transferring the transfer material to the position of each image carrier, and forming a visible image of each color on each image carrier An image forming apparatus comprising: means for transferring an image transferred onto a transfer material by superimposing the image on the transfer material; and means for fixing an image transferred on the transfer material, wherein the optical writing means is any one of claims 1 to 3. An image forming apparatus comprising the optical writing device according to any one of the first to third aspects.