JP5476934B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus.

  In the image forming apparatus, it is necessary to accurately position the image holding body that holds the image. Patent Document 1 discloses a positioning plate for positioning an image carrier within an image forming apparatus. Patent Document 2 discloses a configuration in which parts having similar shapes are stacked as means for increasing the rigidity of a plate body such as this positioning plate.

JP 2006-3735 A JP 2000-77858 A

  SUMMARY OF THE INVENTION An object of the present invention is to suppress a shift in the relative position between image holding members that hold an image.

According to a first aspect of the present invention, there is provided an image forming apparatus comprising: a plurality of image holding bodies each having a rotation shaft that rotates by receiving a driving force, and comprising a plurality of image holding bodies and a plate having a first thickness . A first base and a door that opens or shields a space in which the plurality of image holding bodies are disposed to the outside, and the first facing the first base when the door is in a state of shielding the space. A first support portion and a second support portion that support the rotation shaft of each of the image holding bodies between the first base portion and the second base portion in a state where the two base portions and the door shield the space. there it is fixed to the first base portion, the first support portion of the first consisting of second thickness of the plate member than the thickness integrally, and the second support portion fixed to the second base part When, of the first base portion, the side facing the space on the opposite side, protruding to the opposite side Driving means for applying a driving force to each of the rotating shafts, and a third support portion fixed to a surface of the first base opposite to the side facing the space, and supporting the driving means on the first base A third support portion made of a plate having a third thickness that is thicker than the first thickness, and connecting a plurality of locations where the first support portion is fixed in the first base portion. The first region and the second region connecting the plurality of locations where the third support portion is fixed in the first base portion are portions that overlap each other when viewed from the axial direction of the rotation shaft. and wherein the Rukoto that Yusuke.

The image forming apparatus according to claim 2 is characterized in that, in the image forming apparatus according to claim 1 , the second region of the first base portion is directed to the third support portion to be reinforced. To do.

  According to the image forming apparatus of the first aspect, it is possible to suppress the relative position between the image holding members from being shifted as compared with the case where the rigidity of the support part is equal to or less than the rigidity of the base part.

  According to the image forming apparatus of the second aspect, it is possible to suppress the relative position between the image holding members from being shifted as compared with the case where the rigidity of the first support part is equal to or less than the rigidity of the first base part. it can.

  According to the image forming apparatus of the third aspect, the region connecting the plurality of locations where the first support portion is fixed in the first base portion and the plurality of locations where the third support portion is fixed in the first base portion are connected. The rigidity of the first support portion can be increased as compared with a case where the region does not overlap each other when viewed from the axial direction of the rotating shaft.

1 is a schematic diagram illustrating a configuration of an image forming apparatus according to an embodiment of the present invention. It is a perspective view which shows the structure of a housing | casing. It is a perspective view which shows the structure of the support plate which pinches | interposes and supports both ends, such as a photoconductive drum. It is a perspective view which shows the structure of the support plate which inserts | pinches and supports the both ends of a rotating shaft. It is sectional drawing seen from the arrow VV direction in FIG. It is a figure which shows the state which fixed the drive unit which rotationally drives the rolls, such as a photoconductive drum, to the outer surface of a rear side frame. It is a figure which shows the state which removed the cover of the drive unit shown in FIG. It is a figure which shows the state which fixed the support plate except parts, such as a gearwheel shown in FIG. It is a figure which shows the position of the 1st support plate provided in the back side base, and the fixed position of a drive unit.

<1. Embodiment>
For example, in an image forming apparatus such as a printer or a copier, an open / close cover is provided on the front or side of the housing in order to perform maintenance work such as maintenance and replacement of component parts or work to solve problems such as jamming of recording paper. It has been. In this embodiment, such an image forming apparatus will be described as an example. FIG. 1 is a diagram schematically showing the structure of the image forming apparatus according to the present embodiment. Hereinafter, when the user looks at the image forming apparatus 1 from the front, the left and right right direction is X (+), the left direction is X (−), the front and rear back direction is Y (+), and the front direction is Y (−). ), The upper direction of the height will be described as Z (+), and the lower direction will be described as Z (-). Unless specifically defined, the inner side is a side toward the space in which the exposure apparatus is accommodated when viewed from frames 43 and 44 described later, and the outer side is the exposure apparatus when viewed from the frames 43 and 44. It is on the opposite side of the direction toward the space to be accommodated.

<Configuration of image forming apparatus>
The image forming apparatus 1 constitutes a tandem type full-color printer, and an image processing apparatus that performs image processing on image data sent from a scanner, a personal computer, a telephone line, or the like (not shown) therein (Not shown) is provided. Inside the image forming apparatus 1, four image forming units (image forming portions) 2Y, 2M, 2C, and 2K of yellow (Y), magenta (M), cyan (C), and black (K) are provided. . The image forming units 2Y, 2M, 2C, and 2K are configured such that the yellow (Y) image forming unit 2Y of the first color is relatively high and the black (K) image forming unit 2K of the final color is relatively low. Further, they are arranged in parallel with an interval that is inclined by a certain angle (for example, 10 degrees) with respect to the horizontal direction. As described above, when the four image forming units 2Y, 2M, 2C, and 2K are arranged in a state inclined by a certain angle, the four image forming units 2Y, 2M, 2C, and 2K are arranged horizontally. In comparison, the distance in the width direction is shortened.

These four image forming units 2Y, 2M, 2C, and 2K are basically configured in the same manner, and are rotationally driven at a certain speed by a driving unit 70 described later, and a photosensitive drum 3 as an image holding member, A charging roll 4 for primary charging for charging the surface of the photosensitive drum 3 and a developing unit 6 for developing an electrostatic latent image formed on the photosensitive drum 3 by image exposure by an image exposure device 5 described later with toner. And a cleaning device 7 for cleaning the surface of the photosensitive drum 3. The photosensitive drum 3 is, for example, an organic photosensitive member formed in a drum shape with a diameter of 30 mm and having an overcoat layer on the surface, and is rotated by rotating a rotating shaft 3A (shown in FIGS. 3 and 4). . The charging roll 4 is, for example, a roll-shaped charger in which the surface of a core metal is covered with a conductive layer made of synthetic resin or rubber and having an adjusted electric resistance. A charging bias is applied to the core metal of the charging roll 4. Is used. Further, a cleaning roll for removing foreign matters such as toner adhering to the surface of the charging roll 4 is disposed on the surface of the charging roll 4.
Hereinafter, the image forming units 2Y, 2M, 2C, and 2K will be described as the image forming unit 2 when it is not necessary to identify and describe them.

An image exposure device 5 is provided below the image forming units 2Y, 2M, 2C, and 2K. The image exposure apparatus 5 includes four semiconductor lasers (all not shown) that emit laser beams modulated in accordance with image data. The four laser beams emitted from these semiconductor lasers are deflected and scanned by a polygon mirror, and are also sensitized by the image forming units 2Y, 2M, 2C, and 2K via lenses and mirrors (none shown). Scanning exposure is performed on the body drum 3.
In this embodiment, the image exposure apparatus 5 is disposed along the lower part of the four image forming units 2Y, 2M, 2C, 2K. These four image forming units 2Y, 2M, 2C, 2K It is provided in a state inclined with respect to the direction. For this reason, the optical path lengths of the laser beams that are scanned and exposed on the photosensitive drums 3 of the image forming units 2Y, 2M, 2C, and 2K are equal in the image forming units 2Y, 2M, 2C, and 2K.

  From the image forming apparatus 1, the image data of each color is sequentially output to the image exposure apparatus 5 provided in common to the image forming units 2Y, 2M, 2C, and 2K. The laser beam emitted according to the image data from the image exposure device 5 is scanned and exposed on the surface of the corresponding photosensitive drum 3 to form an electrostatic latent image. The electrostatic latent image formed on the photosensitive drum 3 is developed as a toner image of each color by the developing devices 6Y, 6M, 6C, and 6K. The toner images of the respective colors sequentially formed on the photosensitive drums 3 of the image forming units 2Y, 2M, 2C, 2K are intermediately arranged in an inclined state over the image forming units 2Y, 2M, 2C, 2K. On the intermediate transfer belt 10 as a transfer body, the image is transferred in multiple by the primary transfer roll 11.

The intermediate transfer belt 10 is a belt-like member stretched by a plurality of rolls, and the lower side running region of the belt-like member is low on the downstream side along the running direction and high on the upstream side. It is arranged in an inclined state with respect to the horizontal direction. That is, the intermediate transfer belt 10 is wound around the drive roll 13, the tension roll 15, the backup roll 14, and the first idler roll 12 with a tension, and has a dedicated drive motor excellent in constant speed (see FIG. A drive roll 13 that is rotationally driven by an unillustrated drive is circulated in the direction of the arrow. As the intermediate transfer belt 10, for example, a flexible synthetic resin film such as polyimide is formed in a band shape, and both ends of the synthetic resin film formed in a band shape are connected by means such as welding, thereby being endless. A belt-shaped one is used. The intermediate transfer belt 10 is disposed so as to be in contact with the photosensitive drums 3Y, 3M, 3C, and 3K of the image forming units 2Y, 2M, 2C, and 2K in the lower side running region.
The intermediate transfer belt 10, each primary transfer roll 11, the drive roll 13, the tension roll 15, the backup roll 14, the first idler roll 12, and the like are configured as one intermediate transfer unit 9.

  The recording paper 18 serving as a recording medium is transported along a transport path 21 in which a path is formed by each roller pair from a paper storage unit 24 disposed inside the image forming apparatus 1 with a specified size and material. The In this transport path 21, the recording paper 18 in the paper storage unit 24 is transported to the registration roll 28 once in a state of being separated one by one by a paper feed roller 25 and a pair of paper separating and transporting rollers 26, and then stopped. . The recording paper 18 fed from the paper storage unit 24 is sent to the secondary transfer position of the intermediate transfer belt 10 by a registration roll 28 that is rotationally driven at a predetermined timing. Further, the recording paper 18 on which the toner image of each color is transferred through the secondary transfer position is subjected to a fixing process by heat and pressure by the fixing device 19 and then discharged through the outlet roll 20 of the fixing device 19. 22 is discharged onto a sheet receiving portion 23 provided on the upper portion of the image forming apparatus 1.

  At a position facing the backup roll 14 with the intermediate transfer belt 10 interposed therebetween, a secondary transfer roll 17 serving as a rotating body so as to come into contact with the surface of the intermediate transfer belt 10 while being in contact with the intermediate transfer belt 10 is positioned along the conveyance path 21. Placed in. The yellow (Y), magenta (M), cyan (C), and black (K) toner images transferred onto the intermediate transfer belt 10 in a multiple manner are pressed against each other by the secondary transfer roll 17 that presses against the backup roll 14. Then, it is secondarily transferred onto a recording paper 18 as a recording medium by electrostatic force. The position where the backup roll 14 and the secondary transfer roll 17 face each other with the intermediate transfer belt 10 interposed therebetween is the secondary transfer position.

  In addition, toner cartridges 29Y, 29M, 29C, and 29K are provided between the sheet receiving portion 23 and the intermediate transfer belt 10, and the toner cartridges 29Y, 29M, 29C, and 29K are developed by the developing devices 6Y, 6M, 6C, and 6K. Toner is supplied. Since the toner cartridge 29K containing black (K) toner is frequently used, the toner cartridge 29K is formed in a larger size than other color toner cartridges.

<Case configuration>
Next, the structure of the housing 40 that forms the outer shape of the image forming apparatus 1 will be described with reference to FIGS. 1 and 2. FIG. 2 is a perspective view showing the configuration of the housing.

As shown in FIG. 2, the housing 40 includes four support columns 41 extending along the Z-axis direction and a plurality of beam portions 42 provided between the support columns 41. A rear frame 43 serving as a first base is provided in the Z (+) direction between the columns 41 and 41 located on the (+) side), and between the columns 41 and 41 located on the front side (Y (−) side). A front frame 44 is provided on the Z (+) side. A rectangular through hole 45 (only the rear frame 43 is shown) is formed in the frames 43 and 44. The front frame 44 is provided with a front door 46 serving as a second base that is provided so as to be operable in the direction of arrow a and opens or shields the space for housing the image forming unit 2 (rotating shaft 3A) from the outside. .
A first support plate 50 serving as a first support portion is provided on the inner side (Y (−) side) surface of the rear frame 43, and the inner side (Y (+) side) of the front door 46 provided on the front frame 44. Is provided with a second support plate 60 serving as a second support portion. The second support plate 60 is integrally formed inside the front door 46.

In order to reduce the weight of the image forming apparatus 1, each column 41, the beam portion 42, the frames 43 and 44, etc. constituting the housing 40 have a thickness d1 of 1.0 to 1 as shown in FIG. A plate of 2 mm is used. On the other hand, the support plates 50 and 60 are plates having a thickness d2 of 2.0 mm. Thereby, the rigidity of the support plates 50 and 60 is higher than the rigidity of the frames 43 and 44. For example, when the image forming apparatus 1 is installed in a non-planar place or a non-horizontal place, the frame of the image forming apparatus 1 is distorted to cause a deviation in the arrangement of the optical elements having the photosensitive drum 3. In such a case, color misalignment or the like may occur in the image formed on the recording paper 18. However, since the first support plate 50 is formed by a plate having a thickness d2 thicker than the rear frame 43 and has higher rigidity than the rear frame 43, the rear frame 43 is temporarily distorted. Even in this case, the occurrence of distortion in the first support plate 50 is suppressed.
Therefore, even if the rear frame 43 is distorted and the position of the first support plate 50 is displaced, there is no displacement of the photosensitive drums 3 supported by the first support plate 50 and the second support plate having high rigidity. The distance between the photosensitive drums 3 does not change. For this reason, the deviation of the toner images that are multiple-transferred from the respective photosensitive drums 3 to the intermediate transfer belt 10 is eliminated, and the color shift is suppressed.

<Configuration of support plate>
Here, the mechanism of the image forming unit 2 (photosensitive drum 3) sandwiched between the first support plate 50, the second support plate 60, and the support plates 50 and 60 will be described with reference to FIGS. 3 is a perspective view showing the configuration of the support plates 50 and 60 that sandwich and support both ends of the image forming unit 2 including the photosensitive drum 3, and FIG. 4 shows the support plate that sandwiches and supports both ends of the rotating shaft 3A. The perspective view which shows a structure, FIG. 5 is sectional drawing seen from the arrow VV direction in FIG.
As shown in FIGS. 4 and 5, the first support plate 50 is formed of a rectangular plate body, and rib portions 51 and 51 that are bent toward the outside (Y (+)) are formed on the long side. The tip is fixed to the inner surface of the rear frame 43 by laser welding or the like. In the first support plate 50, shaft insertion holes 52, 52,... Into which the rotation shafts 3A of the respective photosensitive drums 3 are respectively inserted are formed along the longitudinal direction (Y direction) of the first support plate 50. The The shaft insertion hole 52 is formed in a trapezoidal shape.
Here, as shown in FIG. 5, the rotating shaft 3 </ b> A has a coupling 3 </ b> B formed at an end, and is connected to the gear 72 </ b> K of the drive unit 70 via the coupling 3 </ b> B.

On the other hand, as shown in FIGS. 3 and 4, the second support plate 60 is made of a plate body having a larger shape than the first support plate 50, and the first support plate 50 of the first support plate 50 is closed when the front door 46 is closed. .. Are formed at positions facing the respective shaft insertion holes 52, and have the same shape as the shaft insertion holes 52.
The first support plate 50 and the second support plate 60 are made of the same material and the same thickness. When each of the shaft insertion holes 52 and 61 is drilled, the first support plate 50 and the second support plate 60 are combined and drilled. For this reason, the shaft insertion holes 52 and 61 are aligned with burrs and distortions generated during processing. Thereby, the shift | offset | difference of the position in the both ends of 3 A of rotating shafts is suppressed.

<Configuration of drive unit>
Next, a driving unit 70 serving as a driving unit that rotationally drives each roll of the image forming unit 2 will be described with reference to FIGS. 6 to 8.
6 is a view showing a state where the drive unit is fixed to the outer surface of the rear frame 43, FIG. 7 is a view showing a state where the cover of the drive unit shown in FIG. 6 is removed, and FIG. It is a figure which shows the state which fixed the base plate which supports the drive unit 70 except parts, such as a gearwheel shown in it. 6 to 8 show a state when the image forming apparatus 40 of FIG. 2 is viewed from the Y (+) side toward the Y (−) side.
The drive unit 70 applies a driving force to each of the rotating shafts 3 </ b> A protruding outward on the side opposite to the side facing the space, that is, outside the rear frame 43. The drive unit 70 has a base plate 71 serving as a third support portion that supports the drive unit 70, and the base plate 71 supports a shaft of a gear train 72 including gears 72A to 72M. Further, the gear train 72 is covered by a unit cover 73 (shown in FIG. 6). As shown in FIG. 5, the base plate 71 has a thickness d3 of 2.0 mm, which is thicker than the thickness d1 of the rear frame 43. Thereby, the rigidity of the base plate 71 is higher than the rigidity of the rear frame 43.

As shown in FIG. 7, the gear train 72 has a drive gear 72 </ b> A connected to a drive shaft of a motor that is a drive source (not shown). The rotation of the drive gear 72A is transmitted to the gear 72E connected to the drive roll 12 and the driven gear 72F via the driven gears 72B, 72C, 72D.
The rotation of the driven gear 72F is transmitted to gears 72H and 72I connected to the rotation shaft 3A of the photosensitive drums 3M and 3C via the driven gear 72G. The rotation of the gear 72H is transmitted to the gear 72K connected to the rotation shaft 3A of the photosensitive drum 3Y via the driven gear 72J. On the other hand, the rotation of the gear 72I is transmitted to the gear 72M connected to the rotation shaft 3A of the photosensitive drum 3K via the driven gear 72L.

Further, the base plate 71 is fixed to the outer surface of the rear frame 43 at three fixing points 75, 76, 77 as shown in FIG. 8. The method of fixing at the fixing points 75, 76, 77 may be fixed by screwing even by welding.
Of the three fixed points 75, 76, 77, two fixed points 75, 76 are separated from the distance between the photosensitive drums 3 at both ends arranged in parallel in the X direction. The remaining fixing points 77 are closer to the motor than the fixing points 75 and 76, and the distance to one fixing point 75 is shorter than the distance to the other fixing point 76 in the Z (+) direction. It is the position. In the rear frame 43, a triangular region surrounded by the fixing points 75, 76, 77 is directed to the base plate 71 and reinforced, and the rigidity in this region is higher than that of the other portions. Further, the distance L1 from the fixed point 77 to one fixed point 75 is different from the distance L2 to the other fixed point 76.

Next, the attachment position of the first support plate 50 and the rear frame 43 of the drive unit 70 will be described with reference to FIG. FIG. 9 is a view of the rear frame 43 as viewed from the inside (Y (−) side).
In the first support plate 50, the ends of the rib portions 51, 51 extending in the longitudinal direction are fixed to the inner surface of the rear frame 43. On the other hand, the drive unit 70 (base plate 71) is fixed to the outer surface of the rear frame 43 by the fixing points 75, 76, 77 as described above. The triangular area connecting the fixing points 75, 76, 77 of the base plate 71 in the rear frame 43 and the rectangular area where the first support plate 50 is fixed in the rear frame have portions that overlap each other. ing. In other words, solid base plate 71 in the region of the triangle formed by connecting the fixed point 75, 76 and 77 is fixed, the base plate 71 has a rigidity higher than the rear frame 43. Thereby, the rigidity of the part located in the triangular area | region among the back side frames 43 becomes higher than another part.
On the other hand, on the inner side surface of the rear frame 43, the tips of the rib portions 51 of the first support plate 50 are fixed to form a rectangular region. The rectangular area and the triangular area have overlapping portions. Accordingly, the first support plate 50 is provided on the rear frame 43 across the rigid triangular region of the rear frame 43, and the first support plate 50 is distorted by the distortion of the rear frame 43. It is more suppressed. Then, the support position of the rotating shaft 3A is prevented from changing for each photosensitive drum 3, thereby suppressing color misregistration.

<2. Modification>
The above embodiment may be modified as follows.
<2-1>
In the embodiment, the first support plate 50 and the second support plate 60 that support both ends of each rotating shaft 3A are made higher than the rigidity of the frames 43 and 44, but the distortion of the front frame 44 is supported by the shaft. It is difficult to reach the front door 46. For this reason, only the first support plate 50 may be higher in rigidity than the frame 43.

<2-2>
The first support plate 50 according to the embodiment has a shape in which rib portions 51 and 51 are formed on long sides and the tip thereof is fixed to the inner side surface of the rear frame 43. However, the present invention is not limited to this, and any shape may be used as long as the rotating shafts 3A are integrally fixed to the rear frame 43. Further, the region formed when the rotary shaft 3A is fixed to the rear frame 43 and the drive unit 70 are fixed. What is necessary is just to have the part which overlaps with the area | region formed in that case.

<2-3>
In the embodiment, the region where the first support plate 50 is fixed to the rear frame 43 is a rectangle, and the region where the drive unit 70 is fixed to the rear frame 43 is a triangle. The region on the first support plate 50 side may be included in the region on the drive unit 70 side. In short, a part of the region on the first support plate 50 side is included in the region on the drive unit 70 side. It is only necessary to get in.
Further, the fixing of the drive unit 70 to the rear frame 43 is not limited to three points, and may be four points or more. In short, it is sufficient that an area is formed in the rear frame 43.
Furthermore, in the said embodiment, although the rotating shaft 3A was fixed with the 1st support plate 50 in the back | inner side of the housing | casing 40, and the front side was fixed with the 2nd support plate 60 of the front door 46, the front side Of course, the present invention can be applied to the case where the rotary shaft 3A is cantilevered and supported by the first support plate 50 or the front frame is fixed to the front frame.

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 2 ... Image forming unit (image forming means), 3 ... Photosensitive drum (image holding body), 3A ... Rotary shaft, 3B ... Coupling, 10 ... Intermediate transfer belt, 11 ... Primary transfer roll, DESCRIPTION OF SYMBOLS 13 ... Drive roll, 18 ... Recording paper, 40 ... Housing | casing, 41 ... Support | pillar, 42 ... Beam part, 43 ... Rear side frame (1st base), 44 ... Front side frame, 46 ... Front side door (2nd base), DESCRIPTION OF SYMBOLS 50 ... 1st support plate (1st support part), 51 ... Rib part, 52 ... Exterior cover, 52, 61 ... Shaft insertion hole, 60 ... 2nd support plate (2nd support part), 70 ... Drive unit, 71 ... Base plate (third support part), 72 ... Gear train, 75, 76, 77 ... Fixed point

Claims (2)

A plurality of image holders each having a rotation shaft that rotates by receiving a driving force and holding an image;
A first base made of a plate having a first thickness ;
Forming a door that opens or shields the space in which the plurality of image holding bodies are disposed to the outside, the second base facing the first base when the door is in a state of shielding the space;
In a state where the door shields the space, a first support part and a second support part that support a rotation shaft of each image holding body between the first base part and the second base part, is fixed to the first base, a first support portion of the first consisting of second thickness of the plate member than the thickness integrally, and the second support portion fixed to the second base portion,
Driving means for applying a driving force to each of the rotating shafts protruding to the opposite side of the first base on the side opposite to the side facing the space;
A third support portion fixed to a surface of the first base portion opposite to the side facing the space and supporting the driving means on the first base portion; a third support portion being thicker than the first thickness; comprising of a third support portion having a thickness of the plate member, the,
A first region connecting a plurality of locations where the first support portion is fixed in the first base, and a second region connecting a plurality of locations where the third support portion is fixed in the first base. and an image forming apparatus, characterized in that that have a portion overlapping each other when viewed from the axial direction of the rotary shaft. The second region of the first base is directed to the third support and reinforced.
The image forming apparatus according to claim 1.

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