JP2005157030A - Scanning optical apparatus and color image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the cost and to suppress color smear of a color image, by integrating components. <P>SOLUTION: In an inline color image forming apparatus, a scanner fixing bed serves as a dust and protective cover of a scanner. The scanner and a cartridge are accurately positioned on the scanner fixing bed. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a color image forming apparatus such as a color laser beam printer or a color digital copying machine using a plurality of scanning optical devices.

  In a scanning optical device used for a laser beam printer, a digital copying machine or the like, a light beam which is light-modulated from a light source means according to an image signal and emitted is periodically deflected and scanned by an optical deflector such as a rotary polygon mirror, for example. It is focused in a spot shape on the imaging surface on the photosensitive drum by the imaging optical system having the fθ characteristic. The spot on the imaging surface forms an electrostatic latent image in accordance with the main scanning by the optical deflector and the sub scanning by the rotation of the photosensitive drum, and image recording is performed.

With respect to a color image forming apparatus for forming a color image, for example, as described in JP-A-6-183056 and JP-A-10-186254, a plurality of photosensitive optical drums are used by using a plurality of scanning optical devices. Some of them record image information for each color and form a color image by overlapping a plurality of scanning lines.
JP-A-6-183056 JP-A-10-186254

  However, as in the conventional example described above, the scanning optical device including the optical element has the following drawbacks because it requires a dustproof protective cover for preventing the optical element from being contaminated.

  When the space where the optical element in the optical box is arranged is opened in a plurality of directions, the dust-proof protective cover must be attached from the plurality of directions, so the number of parts of the dust-proof protective cover increases. Therefore, it leads to cost increase. In addition, even if an attempt is made to form a dust-proof protective cover with a single component without using a plurality of dust-proof protective covers, the shape becomes complicated, resulting in an increase in cost.

  In the case of an image forming apparatus composed of a plurality of scanning optical devices as disclosed in JP-A-10-186254, a dustproof protective cover must be attached to each scanning optical device, so that it is composed of only one scanning optical device. Cost is high compared to an image forming apparatus.

  Further, in the case of an image forming apparatus composed of a plurality of scanning optical devices, misalignment is likely to occur in the superposition of a plurality of scanning lines. Therefore, in order to output a high-precision image with a small amount of color misregistration, color misregistration correction means Etc. are necessary and difficult to achieve easily.

  The present invention has been made in view of the above-mentioned unsolved problems of the prior art, and the first invention according to the present application is that a space in which an optical element in an optical box is arranged has a plurality of directions. An inexpensive color image forming apparatus capable of outputting a high-precision image by using a part of the housing of the color image forming apparatus as the closing means in at least one direction even when it is open Is intended to provide.

  Further, even when the space in which the optical element is arranged in the optical box is open in a plurality of directions, a part of the housing of the color image forming apparatus is used as a closing means in at least one direction. It is intended to output a high-precision image with small scanning line deviation by positioning a scanning optical device and an image carrier on a part of the casing.

  The second invention according to the present application aims to output a high-precision image with a small scanning line deviation between colors by positioning an image carrier on a scanning optical device.

  In order to achieve the above object, according to a first invention of the present application, scanning optical elements are arranged on both front and back surfaces of an optical box, and at least one of a front surface and a back surface on which the scanning optical elements are disposed is arranged on a color image forming apparatus. A space closed by a part of the housing is formed.

  If the said structure is used, since a dust-proof protective cover is not newly required as an obstruction | occlusion means, it is inexpensive.

  Further, the scanning optical device and the image carrier are positioned and attached to the casing.

  If the above configuration is used, the scanning optical device and the image carrier can be arranged with a high-accuracy relative positional relationship, so that a high-accuracy image with a small scan line deviation can be output.

  In order to achieve the above object, a second invention according to the present application is characterized in that an image carrier is positioned and attached to the scanning optical device.

  If the above configuration is used, the scanning optical device and the image carrier can be arranged in a highly accurate relative positional relationship. In addition, since the relative positional relationship between the plurality of image carriers is maintained with high accuracy, it is possible to output a high-accuracy image with a small shift of scanning lines between the colors.

  As described above, according to the first invention of the present application, by using a part of the housing of the color image forming apparatus as means for closing the space around the scanning optical element in the scanning optical apparatus, Since a separate dustproof protective cover is not required, an inexpensive scanning optical device and color image forming apparatus can be provided. In addition, since the scanning optical device and the image carrier are positioned on the housing of the color image forming apparatus, it is possible to suppress the deviation of the relative positional relationship between the scanning optical device and the image carrier as much as possible, and the scanning line deviation is reduced. A small and very good color image can be output.

  In addition, according to the second invention of the present application, the positional relationship between the scanning optical device and the image carrier is maintained with a very high accuracy, so that an image with a small scan line inclination and dot deviation can be output. it can. In addition, it is possible to provide a color image forming apparatus capable of outputting a very high-definition image that hardly causes a scanning line shift between colors because it is possible to suppress a shift in relative positions of a plurality of image carriers as much as possible. Can do.

(First embodiment)
FIG. 1 is a view showing a color image forming apparatus according to an embodiment of the present invention. In the figure, reference numeral 51 denotes a scanning optical device having a structure described later, 55 denotes an optical box, 1C, 1M, 1Y, and 1BK denote photosensitive drums as image carriers. In the present embodiment, each light beam (laser beam) LC, LM, LY, and LBK that is optically modulated based on image information is emitted from the scanning optical devices 51 and 52, and the corresponding photosensitive drums 1C, 1M, and 1Y, respectively. 1. A latent image is formed by irradiating the surface of 1BK. The latent images are formed on the surfaces of the photosensitive drums 1C, 1M, 1Y, and 1BK, which are uniformly charged by the primary chargers 2C, 2M, 2Y, and 2BK, respectively. Are visualized as cyan, magenta, yellow, and black images, respectively, and are electrostatically transferred in sequence by transfer rollers 5C, 5M, 5Y, and 5BK onto the transfer material P conveyed on the transfer belt 7. A color image is formed. Thereafter, residual toner remaining on the photosensitive drums 1C, 1M, 1Y, and 1BK is removed by the cleaners 6C, 6M, 6Y, and 6BK, and the primary chargers 2C and 2M are formed again to form the next color image. 2Y and 2BK are uniformly charged.

  The transfer material P is stacked on the paper feed tray 21, and is sequentially fed one by one by the paper feed roller 22, and is sent out onto the transfer belt 7 by the registration roller 23 in synchronization with the image writing timing. A cyan image, a magenta image, a yellow image, and a black image formed on the photosensitive drums 1C, 1M, 1Y, and 1BK surfaces while being accurately conveyed on the transfer belt 7 are sequentially transferred onto the transfer material P. The image is transferred to form a color image. The drive roller 24 accurately feeds the transfer belt, and is connected to a drive motor (not shown) with little rotation unevenness. The color image formed on the transfer material P is heat-fixed by the fixing device 25, and then conveyed by the paper discharge roller 26 and outputted outside the apparatus.

  2 and 3 are diagrams for explaining the configuration of the scanning optical apparatus in the first embodiment. FIG. 3 is a top view of FIG.

  The scanning optical device 51 is fixed to a metal stay 53 that is a part of the casing of the image forming apparatus. At that time, the scanning optical device 51 is positioned and fixed to the stay 53 by the positioning means 56 with high accuracy. Also, the cartridge units 54C and 54M for holding the photosensitive drums 1C and 1M, respectively, are assembled to the stay 53 with high accuracy by the positioning means 57, similarly to the scanning optical device 51.

  Beams emitted from the semiconductor lasers 101C and 101M are scanned in different directions by the polygon mirror 102, respectively. The beams LC and LM scanned by the polygon mirror 102 are transmitted through the first scanning lenses 103C and 103M, respectively, changed in direction by the folding mirrors 104C and 104M, and transmitted through the second scanning lenses 105C and 105M. After passing through the emission windows 108C and 108M, an image is formed on the photosensitive drums 1C and 1M. By arranging two pairs of such scanning optical systems in parallel, the scanning light is guided onto the four photosensitive drums.

  According to the present embodiment, even if the scanning optical element is arranged on the front and back of the optical box, the stay also serves as a dust-proof protective cover, so it is less expensive than when a separate dust-proof protective cover is required. It becomes the composition.

  Since the four scanning optical devices are attached to one metal stay, the stay effectively conducts heat when the temperature inside the scanning optical device rises as the scanning optical device is operated. The temperature of the four scanning optical devices becomes uniform. Therefore, since the thermal deformation of the scanning optical element included in each scanning optical device becomes uniform, the relative deviation of the scanning lines of each color can be suppressed small.

  In addition, since the scanning optical device and the cartridge unit are accurately positioned with respect to the stay, the positional relationship between the scanning optical device and the photosensitive drum is maintained with very high accuracy. Accordingly, it is possible to output a high-quality image with a small scan line inclination and a small dot shift.

  In particular, in the case of a tandem type color image forming apparatus using a plurality of photosensitive drums as in this embodiment, when a plurality of scanning lines are overlapped to form an image, the scanning line deviation between the colors is extremely reduced. This is particularly effective.

(Second embodiment)
4 and 5 are diagrams for explaining the configuration of the scanning optical apparatus in the second embodiment. FIG. 5 is a top view of FIG.

  In the optical box 65, scanning optical elements such as a semiconductor laser 111, a polygon mirror 112, a first scanning lens 113, a folding mirror 114, and a second scanning lens 115 are mounted. The scanning optical device 61 is formed of an optical box 65 and a scanning optical element. The scanning optical device 61 is fixed at a predetermined position of a stay 63 that is a part of the casing of the image forming apparatus.

  The cartridge units 64C, 64M, 64Y, and 64Bk that hold the photosensitive drums 11C, 11M, 11Y, and 11Bk are assembled to the optical box 65 with high accuracy by the respective positioning means 67.

  According to this embodiment, since the cartridge unit is directly assembled to the optical box, the positional relationship between the scanning optical device and the photosensitive drum can be maintained with very high accuracy. Therefore, the deviation of the beam irradiation position on the photosensitive drum surface can be suppressed as much as possible. Further, in the case of a tandem type color image forming apparatus using a plurality of photosensitive drums as in this embodiment, a plurality of scanning lines are overlapped to form an image, so that the scanning line deviation between each color is particularly reduced. This is very important. With the configuration of this embodiment, each photosensitive drum is positioned and fixed to one optical box, so that the relative position shift of each photosensitive drum can be suppressed. Therefore, the scanning line deviation between the colors can be extremely reduced, and a good image can be provided.

  Further, since the space around the optical element of the scanning optical device is sealed by the cartridge unit, a separate dustproof protective cover is not required. Therefore, it leads to cost reduction.

  The present invention is not limited to the first and second embodiments described above, and it goes without saying that the same effect can be obtained even when the arrangement of each color and the number of scanning optical devices are different. . In addition, the number of optical boxes is not limited. There is no problem even if a dustproof cover glass is provided on the exit window. As a matter of course, the scanning optical device, the stay and the cartridge unit are not limited to the shape of the present embodiment, and the positioning means and the attaching means for each unit and each component may be any means.

1 is a schematic diagram showing a first embodiment of a color image forming apparatus of the present invention. 1 is a schematic cross-sectional view of an essential part showing a first embodiment of a color image forming apparatus and a scanning optical apparatus of the present invention. FIG. 3 is a schematic view of a main part of a color image forming apparatus and a scanning optical apparatus according to a first embodiment of the present invention, and is a view of FIG. 2 as viewed from above. It is a principal part schematic sectional drawing which shows the 2nd Example of the color image forming apparatus of this invention, and a scanning optical apparatus. FIG. 5 is a schematic view of the essential portions showing a second embodiment of the color image forming apparatus and the scanning optical apparatus of the present invention, and is a view of FIG. 4 as viewed from above.

Explanation of symbols

1C, 1M, 1Y, 1BK, 11C, 11M, 11Y, 11Bk Photosensitive drum 51, 61 Scanning optical device 53, 63 Stay 54C, 54M, 54Y, 54BK, 64C, 64M, 64Y, 64BK Cartridge unit 55, 65 Optical box

Claims (4)

A color image forming apparatus comprising a plurality of combinations of laser light modulated in accordance with image information and an image carrier corresponding to the laser light, and superposing images formed on the plurality of image carriers to form a color image In a scanning optical device comprising a light source, a scanning means, a scanning optical element, and an optical box containing them,
The optical box is attached to the casing of the color image forming apparatus at the outer edge on the image carrier side, and the casing has a plurality of passage openings through which the laser light emitted from the scanning optical apparatus passes. A scanning optical apparatus and a color image forming apparatus, which are provided.   2. A scanning optical device and a color image forming apparatus according to claim 1, wherein the scanning optical elements are arranged on both front and back surfaces of the optical box.   The scanning optical device and the color image forming apparatus according to claim 1, wherein the scanning optical device and the image carrier are positioned in the housing. Color image forming apparatus comprising a plurality of combinations of laser light modulated in accordance with image information and an image carrier corresponding to the laser light, and forming a color image by superimposing images formed on the plurality of image carriers In a scanning optical device comprising a light source, a scanning means, a scanning optical element, and an optical box containing them,
The scanning optical device and the color image forming apparatus, wherein the image carrier is positioned on the scanning optical device.

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