JP2004226884A - Scanning optical device and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dependable scanning optical device in which the thermal deformation of an optical box is suppressed, the superimposing accuracy of a color image is improved and an excellent image is available even in a constitution that has a plurality of deflecting and scanning means. <P>SOLUTION: In a constitution in which the plurality of deflecting and scanning means (a polygon mirror 102 and a motor 106) are arranged side by side in the direction along the bottom face part of an optical box 107, the warpage deformation of the optical box 107 is suppressed by providing a fixing part 112 for fixing the optical box 107 on a frame 109 of the image forming device between two adjacent deflecting and scanning means on the bottom face part. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a scanning optical device that performs optical writing using a laser beam in an electrophotographic image forming apparatus such as an LBP (laser beam printer), a copying machine, a facsimile machine, and the like.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a configuration in which a laser beam is deflected and scanned by a motor-driven polygon mirror has been widely known. In a scanning optical device having such an optical deflector (deflection scanning means), the optical box may be thermally expanded due to heat generation of a motor component or the like. Therefore, in order to prevent optical path fluctuation due to thermal deformation, it is common to firmly screw the optical box to the main body frame of the image forming apparatus.
[0003]
FIG. 7 is a diagram illustrating a configuration of a scanning optical device described in Patent Document 1. In the configuration shown in the figure, the scanning optical device is fixed to the main body frame 11 by four fixing portions 13 provided in the optical box 12, and the optical path fluctuation due to thermal deformation is suppressed.
[0004]
[Patent Document 1]
JP 2000-180766 A
[Problems to be solved by the invention]
In a color image forming apparatus such as a color LBP, a color copying machine, and a color digital facsimile, a scanning optical device having a configuration in which a plurality of optical deflectors are provided in one optical box may be used.
[0006]
When the conventional fixing method is applied to the scanning optical device having such a configuration, the effect on the vibration of the scanning optical device and the vibration received from the outside is obtained, but in the direction (sub-scanning direction) orthogonal to the scanning direction (main scanning direction). The effect of suppressing the thermal deformation of the optical box cannot be sufficiently obtained. This is because the optical box warps and deforms in the sub-scanning direction due to the thermal expansion due to the thermal expansion caused by the heat generated by the plurality of optical deflectors at the connecting portion of the two adjacent optical deflectors. Is shifted.
[0007]
As a result, when forming a color image, a shift occurs in the color superposition, which causes a problem that a good color image cannot be obtained.
[0008]
The present invention has been made in view of the above circumstances, and an object of the present invention is to suppress the thermal deformation of an optical box and superimpose color images even in a configuration including a plurality of deflection scanning means. An object of the present invention is to provide a highly reliable scanning optical device capable of improving accuracy and obtaining a good image.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, a scanning optical device according to the present invention is a scanning optical device in which a plurality of deflection scanning means are arranged in a direction along a bottom portion of an optical box. A fixing unit for fixing the optical box to a frame of the image forming apparatus is provided between the deflection scanning units.
[0010]
Further, the image forming apparatus of the present invention includes a scanning optical device in which a plurality of deflection scanning means are arranged in a direction along a bottom portion of the optical box, and an image on which an image is formed by a light beam emitted from the scanning optical device. In the forming apparatus, a fixing portion for fixing the optical box to a frame of the image forming apparatus is provided between two adjacent deflection scanning units in the bottom surface portion.
[0011]
According to the above configuration, the portion where the thermal expansion due to the heat generated by the deflection scanning unit interferes (the portion between the two adjacent deflection scanning units) is fixed, so that the warp deformation of the optical box due to the thermal expansion is prevented. Can be suppressed.
[0012]
In the above configuration, it is preferable that the bottom portion has a substantially quadrangular shape.
[0013]
Further, it is more preferable that a second fixing portion for fixing the optical box to the frame is provided at each top of the bottom surface.
[0014]
According to this configuration, since the four apexes of the optical box are also fixed, in addition to the warp deformation of the optical box, the extension deformation of both ends of the optical box can be suppressed.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Preferred embodiments of the present invention will be illustratively described in detail below with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention thereto unless otherwise specified. Absent.
[0016]
(1st Embodiment)
FIG. 1 is a diagram illustrating a configuration of a color image forming apparatus according to an embodiment of the present invention.
[0017]
The image forming apparatus includes a plurality of (four in the present embodiment) photosensitive drums 1C, 1M, 1Y, and 1BK as image carriers corresponding to cyan, magenta, yellow, and black, and one scanning optical device 51. It is composed.
[0018]
The scanning optical device 51 has a plurality of (two in this embodiment) deflection scanning means, and each deflection scanning means deflects and scans a plurality of (two in this embodiment) laser beams. , A single device can emit a plurality of laser beams corresponding to each of the photosensitive drums 1C, 1M, 1Y, and 1BK. The detailed configuration of the scanning optical device 51 will be described later.
[0019]
In the present embodiment, light beams (laser beams) LC, LM, LY, and LBK, each of which is light-modulated based on image information, are emitted from the scanning optical device 51 and correspond to the corresponding photosensitive drums 1C, 1M, 1Y, and 1BK. Is illuminated to form a latent image. This latent image is formed on the surfaces of the photosensitive drums 1C, 1M, 1Y, 1BK which are uniformly charged by the primary chargers 2C, 2M, 2Y, 2BK.
[0020]
These latent images are visualized (toner images) into cyan, magenta, yellow, and black images by the developing units 4C, 4M, 4Y, and 4BK, respectively. The toner image is electrostatically transferred onto the transfer material P conveyed on the transfer belt 7 by the transfer rollers 5C, 5M, 5Y, and 5BK in order. Thus, a color image is formed on the transfer material P.
[0021]
Thereafter, the photosensitive drums 1C, 1M, 1Y, and 1BK are cleaned of residual toner remaining on the surfaces thereof by the cleaners 6C, 6M, 6Y, and 6BK, and are again charged with the primary charger 2C to form the next color image. , 2M, 2Y, 2BK.
[0022]
The transfer material P is stacked on a sheet feed tray 21, is fed one by one by a sheet feed roller 22, and is sent out onto a transfer belt 7 by a registration roller 23 in synchronization with an 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.
[0023]
The drive roller 24 accurately feeds the transfer belt 7 and is connected to a drive motor (not shown) having small rotation unevenness. After the transfer material P is heat-fixed on the color image by the fixing device 25, the transfer material P is conveyed by a paper discharge roller 26 or the like and output outside the apparatus.
[0024]
FIG. 2 is a diagram illustrating a configuration of the scanning optical device according to the present embodiment. 2A is a plan sectional view of the scanning optical device, and FIG. 2B is a longitudinal sectional view of the scanning optical device.
[0025]
As shown in the figure, the scanning optical device includes two scanning optical systems 100a and 100b in one optical box 107.
[0026]
The optical box 107 is a hermetically sealed container having a hollow inside and comprising a container 107b and a lid 107a attached to an upper opening of the container 107b. The container 107b has a substantially square bottom surface and side surfaces rising from the bottom surface. Further, the container 107b is provided with two partition walls, and divides the internal space of the optical box 107 into three along the bottom surface.
[0027]
The scanning optical system 100a is arranged in the internal space on the left side in the figure, and the scanning optical system 100b is arranged in the internal space on the right side in the figure. Thereby, the two scanning optical systems are independently sealed, and a high dustproof effect can be realized.
[0028]
Since the two scanning optical systems 100a and 100b have a symmetric structure, only the configuration of the scanning optical system 100a will be described below.
[0029]
The scanning optical system 100a generally includes two semiconductor lasers 101a and 101b, which are light sources of a laser beam, a deflection scanning unit (polygon mirror 102, motor 106) for deflecting and scanning the laser beam, and a photoconductor for deflected laser beam. And two sets of scanning optical members (scanning lenses 103a and 103b, folding mirrors 104a and 104b, and scanning lenses 105a and 105b) for guiding the light to the optical axis.
[0030]
Beams emitted from the two semiconductor lasers 101a and 101b are deflected by the polygon mirror 102 in different directions. The polygon mirror 102 is rotated by a motor 106. The beams B1 and B2 deflected by the polygon mirror 102 pass through the first scanning lenses 103a and 103b, respectively, are changed in direction by the folding mirrors 104a and 104b, and pass through the second scanning lenses 105a and 105b. And form an image on the photosensitive drum.
[0031]
As described above, in the scanning optical system 100a, since two systems of laser beams are deflected and scanned by one deflection scanning unit, cost reduction and downsizing of the scanning optical device can be achieved. In addition, since the number of motors 106, which are heating elements, can be reduced, the amount of heat generated by the scanning optical device can be reduced.
[0032]
In the scanning optical device of the present embodiment, two scanning optical systems 100a and 100b are provided side by side in a direction along the bottom surface of the optical box 107. Since each scanning optical system has deflection scanning means, it can be said that two deflection scanning means are arranged in parallel in the direction along the bottom surface of the optical box 107 (the left-right direction in FIG. 2).
[0033]
Then, fixing portions 112, 112 for fixing the optical box 107 to the main body frame 109 of the image forming apparatus are provided between two adjacent deflection scanning means (a portion 110 in the drawing) of the bottom portion of the optical box 107. Is provided. The fixing portion 112 is provided integrally with the container 107b of the optical box 107, and is fixed by a fixing tool 108b such as a screw.
[0034]
Next, thermal deformation when the optical box 107 thermally expands due to heat generated by the motor 106 will be described with reference to FIG. FIG. 3 shows a comparison with the present embodiment, and shows a state of deformation when the fixing portion 113 is provided in a portion other than the portion 110 between the two sets of scanning optical systems.
[0035]
In the following description, a laser beam passing through the scanning lens 105a is a scanning line (1), a laser beam passing through the scanning lens 105b is a scanning line (2), and a laser beam passing through the scanning lens 105c is a scanning line (3). ), The laser beam transmitted through the scanning lens 105d is referred to as a scanning line (4). In the figure, each scanning line is indicated by a numeral in a circle.
[0036]
The optical box 107 thermally expands due to heat generated by coils (not shown) and the drive IC of the two motors 106a and 106b. Then, the expansion by the motor 106a and the expansion by the motor 106b interfere at substantially the center of the two sets of scanning optical systems. At this time, the optical box 107 is deformed in the warp direction due to stress due to expansion, and the peripheral walls 120 at both ends of the optical box 107 are displaced in a direction to spread outward (see FIG. 3B).
[0037]
When the optical box 107 is deformed in the warp direction, the central portion of the bottom surface of the optical box 107 is displaced away from the main body frame 109 (the direction of arrow A), the angles of the folding mirrors 104b and 104c are largely shifted, and the scanning lines (2) and (3) The position of ()) is greatly shifted. Also, due to the displacement of the peripheral wall 120 of the optical box 107 in the spreading direction, the amount of shift of the folding mirrors 104a and 104d from the initial position increases, and the positions of the scanning lines (1) and (4) are greatly shifted.
[0038]
As described above, when the four corners of the optical box 107 are fixed, the optical path of the scanning lines (1) to (4) fluctuates due to the thermal deformation of the optical box 107, and the image forming position on the photoconductor varies. Occurs. Therefore, when forming a color image, a shift occurs in the color overlay, and a good image cannot be obtained.
[0039]
Next, the state of thermal deformation in the scanning optical device of the present embodiment will be described with reference to FIG.
[0040]
In the present embodiment, a fixing portion 112 is provided between two deflection scanning means (part 110) in the bottom portion of the optical box 107, and the fixing portion 112 is fixed with a fixing tool 108b. Therefore, a force acting in the direction opposite to the stress in the direction away from the main body frame 109 (the direction of arrow A) acts on the intermediate portion between two adjacent deflection scanning means. Accordingly, the stress due to the thermal expansion by the motor 106a and the thermal expansion by the motor 106b is suppressed at substantially the center of the two sets of scanning optical systems, so that the deformation of the optical box 107 in the warp direction is reduced, and the folding mirrors 104b and 104c The angle shift can be reduced, and the position shift of the scanning lines (2) and (3) decreases.
[0041]
FIG. 5 shows the irradiation position shift of the scanning line when the motors 106a and 106b are continuously rotated. 3A shows the irradiation position deviation in the configuration of FIG. 3, and FIG. 3B shows the irradiation position deviation in the configuration of the present embodiment. As can be seen by comparing these graphs, the difference between the irradiation position shifts can be reduced by about 20% by employing a configuration in which the two deflection scanning units are fixed.
[0042]
As described above, according to the configuration of the present embodiment, in a scanning optical device having a plurality of deflection scanning units in one optical box, the warp deformation of the optical box caused by the thermal deformation of the optical box is reduced. As a result, it is possible to improve the overlay accuracy of the colors of the color image and obtain a good image.
[0043]
(Second embodiment)
FIG. 6 is a diagram illustrating a configuration of a scanning optical device according to the second embodiment of the present invention. Here, only the components different from those of the first embodiment will be described, and the same components will be denoted by the same reference numerals and description thereof will be omitted.
[0044]
In the present embodiment, the fixing unit 112 is provided between two adjacent deflection scanning units (part 110), and the optical box 107 is formed on the top (four corners) of the bottom of the optical box 107. A second fixing portion 111 for fixing to the body frame 109 of the apparatus is provided. The second fixing portion 111 is provided integrally with the optical box 107, and is fixed by a fixing tool 108a.
[0045]
According to the configuration of the present embodiment, the warpage of the optical box 107 can be suppressed in the same manner as in the first embodiment, and the extension deformation of both ends of the optical box in the sub-scanning direction can also be suppressed. it can. Therefore, it is possible to further improve the overlay accuracy of the colors of the color image, and it is possible to obtain a better image.
[0046]
The above configuration is merely an example of one embodiment of the present invention, and various modifications can be made within the scope of the technical idea of the present invention.
[0047]
For example, in the above embodiment, two fixing portions 112 are provided, but the number of fixing portions may be one, or three or more. Further, the fixing portion 112 may be provided inside the optical box 107 instead of near the side wall of the optical box 107. In short, if a fixed portion is provided between two adjacent deflection scanning units, the same deformation preventing effect as in the above embodiment can be obtained.
[0048]
In the above-described embodiment, an example in which two deflection scanning units are arranged in parallel has been described. However, the present invention can be suitably applied to a configuration in which three or more deflection scanning units are arranged in parallel. . In the case of three or more, the fixing unit 112 is provided between each two adjacent deflection scanning units.
[0049]
As the fixing members 108a and 108b, a member such as a spring that can be elastically fixed may be used other than the screw.
[0050]
The fixing members 108a and 108b may be the same member, or at least two of the fixing members 108a and 108b used for fixing the optical box 107 to the main body frame 109 may be fixed by the same member.
[0051]
【The invention's effect】
As described above, according to the present invention, the portion where the thermal expansion due to the heat generated by the deflection scanning unit interferes (the portion between two adjacent deflection scanning units) is fixed, so that the optical box caused by the thermal expansion is fixed. Warpage can be suppressed. Therefore, even with a configuration including a plurality of deflection scanning units, it is possible to suppress thermal deformation of the optical box, improve the overlay accuracy of color images, and perform favorable image formation.
[0052]
Further, if the four tops of the optical box are fixed, in addition to the warp deformation of the optical box, the extension deformation of both ends of the optical box can be suppressed, and the overlay accuracy of the color image can be further improved. It becomes possible.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a color image forming apparatus according to an embodiment of the present invention.
FIG. 2 is a diagram illustrating a configuration of a scanning optical device according to the first embodiment of the present invention.
FIG. 3 is a diagram illustrating thermal deformation when the optical box is thermally expanded by heat generated by a motor.
FIG. 4 is a diagram illustrating a state of thermal deformation in the scanning optical device according to the first embodiment of the present invention.
FIG. 5 is a diagram illustrating a displacement of an irradiation position of a scanning line when a motor is continuously rotated.
FIG. 6 is a diagram illustrating a configuration of a scanning optical device according to a second embodiment of the present invention.
FIG. 7 is a diagram showing a configuration of a conventional scanning optical device.
[Explanation of symbols]
1C, 1M, 1Y, 1BK Photosensitive drums 2C, 2M, 2Y, 2BK Primary chargers 4C, 4M, 4Y, 4BK Developers 5C, 5M, 5Y, 5BK Transfer rollers 6C, 6M, 6Y, 6BK Cleaner 7 Transfer belt 11 Body frame 12 Optical box 13 Fixed section 21 Paper feed tray 22 Paper feed roller 23 Registration roller 24 Drive roller 25 Fixer 26 Paper discharge roller 51 Scanning optical devices 100a, 100b Scanning optical systems 101a, 101b Semiconductor laser 102 Polygon mirrors 103a, 103b Scanning lenses 104a, 104b, 104c, 104d Folding mirrors 105a, 105b, 105c, 105d Scanning lenses 106, 106a, 106b Motor 107 Optical box 107a Lid 107b Container 108a, 108b Fixture 109 Frame 110 Site 111 Second Fixing part 112 fixing unit 113 fixing unit 120 wall LC, LM, LY, LBK, B1, B2 laser beam P transfer material

Claims (6)

A scanning optical device in which a plurality of deflection scanning means are arranged in a direction along a bottom portion of the optical box,
A scanning optical device, wherein a fixing portion for fixing the optical box to a frame of an image forming apparatus is provided between two adjacent deflection scanning units in the bottom portion. 2. The scanning optical device according to claim 1, wherein the bottom surface has a substantially rectangular shape. 3. The scanning optical apparatus according to claim 2, wherein a second fixing portion for fixing the optical box to the frame is provided at a top of each of the bottom portions. An image forming apparatus comprising: a scanning optical device in which a plurality of deflection scanning units are arranged in a direction along a bottom portion of the optical box, and performs image formation by a light beam emitted from the scanning optical device.
An image forming apparatus, wherein a fixing portion for fixing the optical box to a frame of the image forming apparatus is provided between two adjacent deflection scanning units on the bottom surface. The image forming apparatus according to claim 4, wherein the bottom portion has a substantially quadrangular shape. The image forming apparatus according to claim 5, wherein a second fixing portion for fixing the optical box to the frame is provided at each top of the bottom portion.

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