JP3980824B2 - Optical writing apparatus and image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical writing apparatus for irradiating a scanning surface of a plurality of image carriers arranged side by side with a light beam and writing a latent image, and a copying machine including the optical writing apparatus and forming a multicolor image The present invention relates to image forming apparatuses such as printers, facsimiles, and plotters.
[0002]
[Prior art]
Conventionally, a latent image is written by irradiating light beams emitted from a plurality of light sources onto four image carriers (for example, photosensitive drums) arranged in parallel, and latent images formed on the respective image carriers. The image is developed with different color developers (for example, yellow, magenta, cyan, and black toners) to be visualized, and then each transfer material such as recording paper carried on a transfer conveyance belt is carried on each image. The images are sequentially conveyed to the transfer section of the body, and each color visible image formed on each image carrier is transferred onto the transfer material, and then the image transferred on the transfer material is fixed to form a multicolor image. There are known tandem color image forming apparatuses.
In such a tandem color image forming apparatus, conventionally, a latent image writing to each image carrier is separately performed by an optical writing device provided individually for each image carrier. An optical writing device using an optical deflector comprising a polygon mirror and its driving motor is relatively expensive, and it is necessary to provide an optical writing device for each image carrier individually in terms of component cost and manufacturing cost. There's a problem. In addition, since a large installation space is required to install a plurality of optical writing devices having optical deflectors corresponding to the number of image carriers, there is a problem that the entire image forming apparatus is increased in size.
[0003]
Therefore, in order to reduce the cost and size of a tandem color image forming apparatus, as a means for performing optical writing on a plurality of image carriers, a light deflector is shared by a plurality of light sources, and one light deflector is used. An optical writing apparatus is known in which light beams from a plurality of light sources are simultaneously deflected and scanned to irradiate a plurality of image carriers to perform optical writing.
[0004]
[Problems to be solved by the invention]
As described above, in an optical writing apparatus that performs optical writing by simultaneously deflecting and scanning light beams from a plurality of light sources with one optical deflector and irradiating a plurality of image carriers, the optical deflector 2 is the center. The optical system is arranged symmetrically with respect to the direction and guides and forms a plurality of light beams deflected and scanned by an optical deflector on the corresponding scanned surface. Since it consists of a number of corresponding optical members, the optical writing device may not be made compact depending on the arrangement of these optical members.
Therefore, the present invention aims to propose a housing structure and an arrangement configuration of an optical system that can achieve further downsizing of the optical writing device and can ensure strength , and includes a compact optical writing device. Another object of the present invention is to provide an image forming apparatus.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, in the present invention, a plurality of light sources, an optical deflector that distributes and deflects light beams from the plurality of light sources in two symmetric directions, and the two directions around the optical deflector. And an optical system for guiding and imaging a plurality of light beams deflected and scanned by the optical deflector on the corresponding scanned surfaces, respectively, including a plurality of light sources, optical deflectors and optical systems. In the optical writing device housed in a housing, the housing has a base on which the optical deflector and the optical system are disposed, and a frame-like side wall surrounding the base, and the base is formed on the side wall. A plurality of light sources disposed on a side wall of the housing; and the optical deflector disposed at a substantially central portion of the base to constitute the optical system . 1 imaging lens and 1st fold On the upper surface side of the return mirror the base, the divided second imaging lens and second mirrors constituting the optical system on the lower surface side of the base and configured arranged, and said light to said base deflectors are respectively provided opening passing through the plurality of light beams in the two directions of each centered is in correspondence with the plurality of light beams, in each of the two directions around the optical deflector Between the opening and the opening in the base, there is a portion standing on the bottom surface of the base, and the second imaging lens is provided on the portion standing on the bottom surface of the base. (Claim 1).
[0007]
Further, according to the present invention, a plurality of image carriers arranged side by side, an optical writing means for writing a latent image by irradiating a light beam onto the scanning surface of the plurality of image carriers, and formed on each image carrier Development means for developing the latent image formed with different color developers to make visible images, and a visible image of each color formed on each image carrier by sequentially transferring the transfer material to the position of each image carrier in the image forming apparatus and means for transferring superimposed on the transfer material, the means for fixing the image transferred onto the transfer material, as the optical writing unit, the optical writing according to claim 1 described above The apparatus includes a device (claim 2 ).
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the configuration, operation, and operation of the optical writing apparatus and the image forming apparatus according to the present invention will be described in detail based on the illustrated embodiments.
1 is a cross-sectional view of an optical writing apparatus showing an embodiment of the present invention, and FIG. 2 is a schematic configuration diagram showing an example of an image forming apparatus including the optical writing apparatus shown in FIG. FIG. 2 is a plan view showing the configuration of the substrate upper surface side of the optical writing device shown in FIG. 1. FIG. 1 shows a cross-sectional configuration taken along the line AA ′ of FIG. 4 is a cross-sectional view showing the structure of the housing of the optical writing device shown in FIG. 1, and FIG. 5 shows the arrangement of the optical deflector and the optical system extracted from the configuration of the optical writing device shown in FIG. FIG. 6 shows the arrangement of the light source unit, the optical deflector, and the optical system extracted from the configuration shown in FIG.
[0009]
The image forming apparatus shown in FIG. 2 is a full-color image forming apparatus in which a plurality of drum-shaped photoconductive photoreceptors (hereinafter referred to as photoreceptor drums) 1, 2, 3, and 4 are juxtaposed as a plurality of image carriers. The four photosensitive drums 1, 2, 3, and 4 display, for example, images corresponding to yellow (Y), magenta (M), cyan (C), and black (Bk) in order from the right in the drawing. (The order of colors is not limited to this, and can be arbitrarily set). Around each of the four photosensitive drums 1, 2, 3, 4 is a charging unit (charging roller, charging brush, charging charger, etc.) 6, 7, 8, 9, exposure portions of the light beams L 1, L 2, L 3, and L 4 from the optical writing device 5, developing portions (developing devices for each color of Y, M, C, and Bk) 10, 11, 12, and 13, and transfer A transfer belt 22 including transfer belts 22a and transfer means (transfer rollers, transfer brushes, etc.) 14, 15, 16, 17 disposed on the back surface thereof; and cleaning units (cleaning blades, cleaning brushes, etc.) 18, 19, 20, 21 and the like are arranged, and image formation of each color can be performed on each of the photosensitive drums 1, 2, 3, and 4.
[0010]
The optical writing device 5 is disposed obliquely above an image forming unit in which four photosensitive drums 1, 2, 3, and 4 are arranged in parallel, and is fixed to body frames 29 and 30 of the image forming apparatus. The optical writing device 5 includes four light source units 52, 53, 54, and 55 and light beams L1, L2, and L2 from the light source units as shown in the configuration examples of FIGS. An optical deflector 62 that deflects and scans L3 and L4 in two symmetrical directions, and a plurality of lights that are symmetrically arranged in the two directions around the optical deflector 62 and deflected and scanned by the optical deflector 62 Optical systems (imaging lenses 63, 64, 69, 70, 71, 72) for guiding the beams L1, L2, L3, and L4 onto the scanned surfaces of the corresponding photosensitive drums 1, 2, 3, and 4, respectively. And optical path folding mirrors 65, 66, 67, 68, 73, 74, 75, 76, 77, 78, 79, 80, etc.). It is stored inside.
[0011]
More specifically, the housing 50 includes a base 50A on which the optical deflector 62 and the optical system are disposed, and a frame-like side wall 50B surrounding the base 50A, and the base 50A is substantially at the center of the side wall 50B. The four light source units 52, 53, 54, and 55 are arranged on the side wall 50B of the housing 50, and the light deflector 62 is substantially at the center of the base 50A of the housing 50. And optical members constituting the optical system (imaging lenses 63, 64, 69, 70, 71, 72, mirrors 65, 66, 67, 68, 73, 74, 75, 76, 77 for turning back the optical path). , 78, 79, 80, etc.) are arranged separately on both surfaces (upper surface side and lower surface side) of the base 50A. Covers 87 and 88 are provided at the upper and lower portions of the housing 50, and an opening through which the light beam passes is provided in 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 is formed by integrally forming the base 50A and the side wall 50B by resin molding, and the cross-sectional structure of the housing 50 has a substantially H-shaped structure. . 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 device 5 is attached.
[0012]
In this 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 receiver, etc.) (not shown) is used as a light source driving signal. The light source (semiconductor laser (LD)) in each light source unit 52,53,54,55 is driven according to it, and a light beam is radiate | emitted. The light beams emitted from the light source units 52, 53, 54, and 55 pass through the cylindrical lenses 56, 57, 58, and 59 for surface tilt correction and reach the optical deflector 62 directly or via the mirrors 60 and 61. The two-stage polygon mirrors 62a and 62b rotated at a constant speed by the polygon motor 62c are deflected and scanned in two symmetrical directions. 1 and 5, the polygon mirror is divided into two upper and lower stages for the L2 and L3 light beams and the L1 and L4 light beams, but is deflected by one thick polygon mirror. It may be configured to scan.
[0013]
The light beams deflected and scanned in two directions by two beams by the polygon mirrors 62a and 62b of the optical deflector 62 pass through the first imaging lenses 63 and 64, each composed of an upper and lower two-layer fθ lens, for example. After being folded by the first folding mirrors 65, 66, 67 and 68 and passing through the opening of the base 51, the second imaging lenses 69, 70, 71 and 72 made of, for example, a long toroidal lens are passed through. The photosensitive drums 1, 2, 3, 3 for the respective colors are passed through the second folding mirrors 73, 75, 77, 79, the third folding mirrors 74, 76, 78, 80, and the dustproof glasses 83, 84, 85, 86. 4 is irradiated onto the surface to be scanned and an electrostatic latent image is written.
[0014]
In the optical writing device 5 described above, the four light source units 52, 53, 54, and 55 are composed of a semiconductor laser (LD) as a light source and a collimating lens that collimates the emitted light beam of the semiconductor laser. The black light source unit (for example, the light source unit of reference numeral 54), which is frequently incorporated in the monochrome image formation, has two or more light sources (for example, a light source unit denoted by reference numeral 54). LD) and a collimating lens may be used. In the case of a multi-beam configuration, if the light source unit is configured to be rotatable about 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. It becomes possible to switch the pixel density (for example, 600 dpi, 1200 dpi, etc.).
[0015]
Further, a synchronization detection mirror (not shown) for taking out the light beam at the scanning start position in the main scanning direction is provided in the optical path of each of the light beams L1, L2, L3, and L4, and is reflected by the synchronization detection mirror. The light beam is received by the synchronization detectors 81 and 82 as shown by broken lines in FIG. 5 and a scanning start synchronization signal is output. Further, as shown in FIG. 5, the third folding mirrors 74, 76, 78 arranged in the optical path of the light beams L1, L2, L3 are provided with stepping motors 92, 93, 94 for skew adjustment. The deviation of the scanning line positions of the L1, L2, and L3 light beams is corrected based on the scanning line position of the L1 light beam.
[0016]
The scanning direction of the light beam deflected and scanned by the optical deflector 62 is the main scanning direction, which is the axial direction of each photosensitive drum. The direction perpendicular to the main scanning direction is the sub-scanning direction, which is the rotation direction of the photosensitive drum (movement direction of the surface of the photosensitive drum), and further the conveyance direction 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.
[0017]
As shown in FIG. 2, a transfer conveyance belt 22a stretched between a driving roller and a plurality of driven rollers is disposed below the four photosensitive drums 1, 2, 3, 4 arranged in parallel. It is conveyed by the driving roller in the direction indicated by the arrow in the drawing. In addition, a plurality of paper feeding units 23 and 24 that store transfer materials such as recording paper are installed at the lower part of the main body of the image forming apparatus, and the transfer materials stored in the paper feeding units 23 and 24 feed paper. The paper is fed to the transfer / conveyance belt 22a via the rollers, the conveyance rollers, and the registration rollers 25, and is carried and conveyed by the transfer / conveyance belt 22a.
[0018]
The latent images formed on the photoconductors 1, 2, 3, and 4 by the optical writing device 5 are developed with toners of Y, M, C, and Bk colors of the developing units 10, 11, 12, and 13, respectively. The visualized toner images of each color of Y, M, C, and Bk are carried on the transfer conveyance belt 22 a by the transfer units 14, 15, 16, and 17 of the transfer conveyance device 22. The images are sequentially superimposed on the transferred material. The transfer material onto which the four color images have been transferred is conveyed to the fixing unit 26, where the image is fixed by the fixing unit 26, and then discharged onto the paper discharge tray 28 by the paper discharge roller 27.
[0019]
The configuration and operation of the optical writing device and the image forming apparatus according to the present invention have been described above. In the optical writing device 5 according to the present invention, the housing 50 is provided with the optical deflector 62 and the optical system. The base 50A has a frame-like side wall 50B surrounding the base 50A, and the base 50A is provided at a substantially central portion of the side wall 50B to partition the housing 50 vertically. , 54, 55 are disposed on the side wall 50B of the housing 50, and the optical deflector 62 is disposed at a substantially central portion of the base 50A of the housing 50, and constitutes an optical member (imaging lenses 63, 64, 69,. 70, 71, 72, mirrors 65, 66, 67, 68, 73, 74, 75, 76, 77, 78, 79, 80, etc. for turning back the optical path) are divided into both surfaces (upper surface side and lower surface side) of the base 50A. The Since the size of the housing 50 of the optical writing device is less than half of the optical path length while securing the entire optical path length of the optical system, the optical writing device can be made compact. it can.
[0020]
As shown in FIG. 4, the housing 50 is formed by integrally forming a base 50A and a side wall 50B by resin molding, and the cross-sectional structure of the housing 50 is a substantially H-shaped structure. As a result, the housing 50 can be made compact and the strength can be ensured, and a structure in which vibration due to the rotation of the optical deflector 62 hardly occurs and the 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 replaced with the image forming apparatus. Even in the state of being fastened to the frames 29 and 30 of the main body, the housing 50 is hardly distorted due to temperature change, and the optical characteristics can be maintained.
[0021]
Since the image forming apparatus having the configuration shown in FIG. 2 includes the compact optical writing device 5 having the configuration shown in FIGS. 1 and 3 to 6, the image forming apparatus is smaller than the conventional tandem color image forming apparatus. A low-cost color image forming apparatus can be provided. Further, as shown in FIG. 2, an image forming unit in which four photosensitive drums 1, 2, 3, and 4 are arranged side by side, an optical writing device 5, and a transfer conveying device 22 are installed obliquely, so that a color image is obtained. Further miniaturization of the forming device can be achieved.
[0022]
【The invention's effect】
As described above, in the present invention, a plurality of light sources, an optical deflector that distributes and deflects light beams from the plurality of light sources in two symmetric directions, and the two directions around the optical deflector. A plurality of light beams which are symmetrically arranged and deflected and scanned by the light deflector to guide and form images on the corresponding scanned surfaces, respectively, and the plurality of light sources, the light deflector and the optical system are provided in one 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 the base is substantially the same as the side wall. A first partition that is provided in a central portion and partitions the housing up and down, the plurality of light sources are disposed on a side wall of the housing, and the optical deflector is disposed in a substantially central portion of the base to constitute the optical system . Imaging lens and first fold The mirror on the upper surface side of the base, since the second imaging lens and second mirrors constituting the optical system has a structure that is separately disposed on the lower surface side of the base, the optical path length of the entire optical system The optical writing apparatus can be made compact while ensuring the above.
[0023]
Further, the optical writing device according to the present invention, in addition to the above configuration, opening said foundation passing through said plurality of light beams to each of the two directions around the optical deflector of the plurality Each of the light beams is provided in correspondence with each other, and in each of the two directions centered on the optical deflector, there is a portion erected on the lower surface of the base between the openings in the base. In addition, since the second imaging lens is provided at a portion standing on the lower surface of the base, the housing can be made compact and the strength can be secured, and the optical deflector can be rotated. It becomes a structure in which vibration or the like hardly occurs, and optical characteristics can be maintained. Further, since the housing 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. 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 the frame of the image forming apparatus main body to which the optical writing device is attached. Therefore, even when the housing of the optical writing apparatus is fastened to the frame of the main body of the image forming apparatus, the distortion of the housing due to temperature change is not easily generated, and the optical characteristics can be maintained.
[0024]
Further, according to the present invention, a plurality of image carriers arranged side by side, an optical writing means for writing a latent image by irradiating a light beam onto the scanning surface of the plurality of image carriers, and formed on each image carrier Development means for developing the latent image formed with different color developers to make visible images, and a visible image of each color formed on each image carrier by sequentially transferring the transfer material to the position of each image carrier In the image forming apparatus comprising means for transferring the image on the transfer material and means for fixing the image transferred onto the transfer material, the optical writing device having the above-described compact configuration is used as the optical writing means. Since the structure is provided, a small and low-cost tandem color image forming apparatus can be provided.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an optical writing device showing an embodiment of the present invention.
FIG. 2 is a diagram illustrating an example of the present invention, and is a schematic configuration diagram illustrating an example of an image forming apparatus including the optical writing device illustrated in FIG.
3 is a plan view showing the configuration of the substrate upper surface side of the optical writing device shown in FIG. 1; FIG.
4 is a cross-sectional view showing the structure of the housing of the optical writing device shown in FIG. 1. FIG.
5 is a schematic configuration diagram showing an arrangement configuration of an optical deflector and an optical system extracted from the configuration of the optical writing device shown in FIG. 1; FIG.
6 is a schematic configuration diagram showing an arrangement configuration of a light source unit, an optical deflector, and an optical system extracted from the configuration shown in FIG. 3;
[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: Development unit (development device for each color of Y, M, C, Bk)
14, 15, 16, 17: transfer means 18, 19, 20, 21: cleaning unit 22: transfer transport device 22a: transfer transport belt 23, 24: paper feed unit 25: registration roller 26: fixing unit 27: paper discharge roller 28: Paper discharge trays 29, 30: Image forming apparatus main body frame 50: Housing 50A: Base 50B: Side walls 52, 53, 54, 55: Light source units 56, 57, 58, 59: Cylindrical lenses 60, 61: Mirror 62 : Optical deflectors 62a, 62b: Polygon mirror 62c: Polygon motors 63, 64: First imaging lenses 65, 66, 67, 68: First folding mirrors 69, 70, 71, 72: Second imaging Lenses 73, 75, 77, 79: second folding mirrors 74, 76, 78, 80: third folding mirrors 81, 82: synchronization detectors 83, 84, 5,86: dust-proof glass 87, 88: cover

Claims (2)

A plurality of light sources, an optical deflector that distributes and deflects light beams from the plurality of light sources in two symmetric directions, and is disposed symmetrically in the two directions with the optical deflector as a center. In an optical writing apparatus comprising an optical system for guiding and imaging a plurality of light beams to be deflected and scanned on corresponding scanning surfaces, and housing a plurality of light sources, optical deflectors and optical systems in one 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 the base is provided at a substantially central portion of the side wall to move the housing up and down. With a structure that partitions
The plurality of light sources are disposed on a side wall of the housing, the optical deflector is disposed at a substantially central portion of the base, and a first imaging lens and a first folding mirror constituting the optical system are provided on the base. On the upper surface side, the second imaging lens and the second folding mirror constituting the optical system are arranged separately on the lower surface side of the substrate, and the optical deflector is centered on the substrate . They are respectively provided opening passing through the plurality of light beams to each of two directions corresponding to said plurality of light beams, and the opening in the base in each of the two directions around the optical deflector An optical writing device having a portion standing on the lower surface of the base between the opening and the second imaging lens provided on the portion standing on the lower surface of the base . A plurality of image carriers arranged side by side, an optical writing means for writing a latent image by irradiating a light beam onto the scanning surface of the plurality of image carriers, and a latent image formed on each image carrier Developing means that develops with different color developers to make visible images, and sequentially transfers the transfer material to the position of each image carrier and overlays each color visible image formed on each image carrier on the transfer material In an image forming apparatus comprising means for transferring together and means for fixing an image transferred on a transfer material,
An image forming apparatus comprising the optical writing device according to claim 1 as the optical writing unit.

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