JP2007178730A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus having a mounting structure for a superposition unit achieving high accuracy with simple structure of a small number of parts. <P>SOLUTION: The superposition unit is coupled with an image forming unit and an image forming apparatus main body by gap fit coupling that a positioning pin is fit in a positioning means comprising a hole or a groove with a gap, and interference fit coupling that the positioning pin is fit in the positioning means while interposing a cap member. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus that forms an image on a recording material, and more particularly to an image forming apparatus that forms an image by an electrophotographic process.

  In an image forming apparatus that forms an image by an electrophotographic process, a toner image is formed on an image forming body such as a photoconductor, and the formed toner image is transferred to a recording material and fixed to form an image.

  In recent years, the need for higher image quality for electrophotographic image forming apparatuses has increased, and the need for higher image quality has become more severe due to the trend toward colorization.

  A color image is formed by superimposing single color images. However, one of the problems in a color image forming apparatus is to eliminate color misregistration due to positional misalignment during superimposition.

  In Patent Document 1, in an image forming apparatus having a plurality of image forming units and a superposition unit having a transfer belt that travels along the plurality of image forming units, the most upstream unit and the most downstream of the plurality of image forming units. Positioning by abutment is performed at the position of the unit, and spring biasing means is used for this positioning.

In Patent Document 2, positioning between an upper unit that supports a photosensitive drum and a lower unit that supports a transfer unit is performed using a spring that can swing vertically and horizontally.
JP-A-7-261493 JP-A-8-30054

  In the positioning structure for positioning the transfer portion with respect to the image forming unit using a spring as in Patent Documents 1 and 2, in addition to the positioning abutment structure, a spring and a spring support structure for supporting the spring are required. As a result, the structure becomes complicated and the cost increases, and the assembly process becomes complicated.

  An object of the present invention is to provide an image forming apparatus in which a transfer unit is positioned with a simple structure and high positional accuracy.

The object is achieved by the following invention.
1.
In an image forming apparatus having an image forming unit for forming a single color toner image and an overlapping unit for forming a multicolor toner image by superimposing the single color toner images formed in the image forming unit,
In the first position, the first positioning means and a first positioning pin that fits into the first positioning means with a gap are coupled with a gap.
In the second position, the second positioning means, the second positioning pin fitted into the second positioning means, and the interference fit coupling by the cap member interposed between the second positioning means and the second positioning pin,
An image forming apparatus, wherein the image forming unit and the superposition unit are combined.
2.
The image forming unit develops an image forming body, latent image forming means for forming an electrostatic latent image on the image forming body, and the formed electrostatic latent image to form a toner image on the image forming body. 2. The image forming apparatus according to 1, further comprising a developing unit, wherein the superimposing unit includes an intermediate transfer member that carries the toner image transferred from the image forming member.
3.
The image forming unit develops an image forming body, latent image forming means for forming an electrostatic latent image on the image forming body, and the formed electrostatic latent image to form a toner image on the image forming body. 2. The image forming apparatus according to 1, further comprising a developing unit, wherein the superimposing unit includes a recording material conveyance body that conveys a recording material that carries the toner image transferred from the image forming body. .
4).
The superposition unit has an image forming body, and the image forming unit develops a latent image forming means for forming an electrostatic latent image on the image forming body and a toner image by developing the formed electrostatic latent image. 2. The image forming apparatus as described in 1 above, further comprising developing means for forming.
5.
The superposition unit has a superposition unit frame provided with the first positioning means, and the image forming unit has a first image formation unit frame provided with a third positioning means, The image forming apparatus according to any one of claims 1 to 4, wherein the gap fitting coupling is formed by inserting a positioning pin into the first and third positioning means.
6).
The second positioning pin is formed on the overlapping unit frame, the second positioning means is provided on the first image forming unit frame, and the cap member is inserted into the second positioning pin. The image forming apparatus according to any one of 1 to 5 above.
7).
In an image forming apparatus having an image forming apparatus main body and an overlay unit,
In the first position, the first positioning means and a first positioning pin that fits into the first positioning means with a gap are coupled with a gap.
In the second position, the second positioning means, the second positioning pin fitted into the second positioning means, and the cap member interposed between the second positioning means and the second positioning pin are coupled with an interference fit. ,
An image forming apparatus, wherein the image forming apparatus main body and the superposition unit are combined.
8).
The image forming apparatus main body has a main body frame provided with the first positioning pins, and the superposition unit has a superposition unit frame provided with the first positioning means. The image forming apparatus described.
9.
An image forming unit that forms a toner image to be transferred to the superposition unit; and the superposition unit frame is provided with the second positioning pin, and the image forming unit is a second image forming unit. 9. The image forming apparatus according to 8, wherein the image forming apparatus has a frame, and the second image forming unit frame is provided with the second positioning unit.
10.
10. The image forming apparatus according to any one of 1 to 9, wherein the first positioning unit includes a hole.
11.
11. The image forming apparatus according to any one of 1 to 10, wherein the second positioning unit includes a groove.
12
6. The image forming apparatus according to 5, wherein the third positioning unit includes a hole.
13.
An image forming unit for forming a toner image transferred to the superposition unit, and the image forming unit and the superposition unit are coupled by the gap fit coupling and the interference fit coupling. The image forming apparatus according to 7 above.

  According to the present invention, high-accuracy positioning is performed simply by attaching a cap member for positioning between the image forming unit, the image forming apparatus main body, and the superposition unit. Thus, an image forming apparatus is realized in which the superposition unit is positioned and assembled with high accuracy with respect to the image forming unit.

(1) Embodiment 1
<Structure of image forming apparatus>
Hereinafter, the present invention will be described with reference to embodiments, but the present invention is not limited to the embodiments. FIG. 1 is a schematic configuration diagram of a color image forming apparatus according to Embodiment 1 of the present invention.

  The image forming apparatus 100 is called a full-color image forming apparatus having a tandem configuration, and includes a plurality of sets of image forming units Y, M, C, and K, an overlapping unit T, a paper feed roller R1, and the like. A sheet feeding / conveying section 21 and a fixing device 24 are provided. A document image reading device SC is disposed on the upper part of the image forming apparatus main body A.

  Further, the image forming apparatus main body A is provided with a detachable drawer unit D, and the drawer unit D is provided with image forming units Y, M, C, K, and an overlapping unit T. . A drawer unit D as an image forming unit for forming an image on the recording material P can be guided and pulled out from an image forming apparatus main body H called a process cartridge by a rail 80R.

  In FIG. 1, the image forming units Y, M, C, and K are vertically arranged in the vertical direction, and the overlapping unit T is arranged on the left side of the photosensitive member constituting each image forming unit. The superimposing unit T includes an endless belt-shaped intermediate transfer body 70 wound around a plurality of rollers 70R, and primary transfer rollers 5Y and 5M that transfer the toner images formed by the respective image forming units onto the intermediate transfer body 70. 5C, 5K, and a cleaning device 6A that removes toner remaining on the intermediate transfer member 70. Next, an image forming unit performed in the image forming apparatus 100 will be described.

  The image forming unit Y for forming a yellow image includes a drum-shaped photoreceptor 1Y, a charging device 2Y, an exposure device 3Y, a developing device 4Y, and a primary transfer roller as a primary transfer device disposed around the photoreceptor 1Y. 5Y and a cleaning device 6Y. The image forming unit M for forming a magenta image includes a drum-shaped photoconductor 1M, a charging device 2M arranged around the photoconductor 1M, an exposure device 3M, a developing device 4M, and a primary transfer roller as a primary transfer device. 5M and a cleaning device 6M. The image forming unit C that forms a cyan image includes a drum-shaped photoreceptor 1C, a charging device 2C, an exposure device 3C, a developing device 4C, and a primary transfer roller as a primary transfer device disposed around the photoreceptor 1C. 5C and a cleaning device 6C. The image forming unit K for forming a black image includes a drum-shaped photoconductor 1K, a charging device 2K arranged around the photoconductor 1K, an exposure device 3K, a developing device 4K, a primary transfer roller 5K as a primary transfer device, It has a cleaning device 6K.

  The superimposing unit T includes a semiconductive endless belt-shaped intermediate transfer body 70 that is wound around a plurality of rollers 70R and is rotatably supported.

  The respective color images formed by the image forming units Y, M, C, and K are sequentially transferred onto the rotating intermediate transfer body 70 by the primary transfer rollers 5Y, 5M, 5C, and 5K, and are superposed to be color toners. An image is formed.

  The recording material P accommodated in the paper feed cassette 20 is fed one by one by the first paper feed roller R1, conveyed by the paper feed roller R2, and temporarily stopped at the upstream position of the registration roller R3. After the temporary stop, the recording material P is conveyed to the transfer position by the registration roller R3 in synchronization with the image forming units in the image forming units Y, M, C, and K. The color toner image is transferred onto the recording material P at the transfer position formed by the roller 70R, which is one of the rollers that support the intermediate transfer body 70, and the transfer roller 5A.

  The recording material P to which the color toner image has been transferred is fixed by the fixing device 24, is sandwiched between the paper discharge rollers 25, and is placed on a paper discharge tray 26 outside the apparatus.

  In the double-sided image forming unit, the recording material P having an image formed on the front surface travels downward after passing through the fixing device 24 and is turned upside down in the reverse conveyance path 27 and then fed again to the registration roller R3. . After the back image is formed and fixed on the re-recorded recording material P, the recording material P is discharged to the discharge tray 26.

  On the other hand, after the color toner image is transferred to the recording material P by the secondary transfer roller 5A as the secondary transfer means, the residual toner is removed by the cleaning device 6A from the intermediate transfer body 70 from which the recording material P is separated by curvature.

  FIG. 2 is a diagram showing the relationship among the image forming apparatus main body H, the superposition unit T, and the drawer unit D as an image forming unit. A drawer unit D is mounted on the image forming apparatus main body H and can be pulled out as indicated by an arrow W. The drawer unit D includes image forming units Y, M, C, and K that form a single-color image, and an overlapping unit T that carries the formed and transferred toner image. The superimposing unit T has the superposing unit frames 71 and 72 for the image forming apparatus main body H and the drawer unit D, the front frame 80 (first image forming unit frame) of the drawer unit D, and the intermediate frame 81 ( The second image forming unit frame) and the rear frame 82 (main body frame) of the image forming apparatus main body H are positioned with high accuracy by the gap fitting coupling and the interference fitting coupling described below.

  3 shows the front frame 80 of the drawer unit D, FIG. 4 shows the intermediate frame 81 of the drawer unit D, and FIG. 5 shows the back frame 82 of the image forming apparatus main body H. 4 and 5 are views of the intermediate frame 81 and the back frame 82 as viewed from the troublesome side of the image forming apparatus, that is, from the direction opposite to the arrow W in FIG. 2, and FIG. It is the figure seen from the back side of the forming apparatus, ie, the direction of the arrow W of FIG.

  The front frame 80 has holes 80Y, 80M, 80C, and 80K, and these holes support the image forming units Y, M, C, and K, respectively. Similarly, the intermediate frame 81 has holes 81Y, 81M, and 81C, and these holes support the image forming units Y, M, and C, respectively. The image forming unit K is fitted into a recess 81K provided at the lower part of the intermediate frame 81.

  Next, the support structure of the overlapping unit T will be described.

The overlapping unit T needs to be positioned and attached with an accuracy of micron order so as not to cause color misregistration. In order to achieve such a high positional accuracy, in the present invention, a clearance fit and an interference fit are used in combination.
<Gap fitting connection>
FIG. 6 is a perspective view of the overlapping unit T. FIG.

  The overlapping unit T is formed in a box shape as shown in the figure by overlapping unit frames 71 and 72 that support the shaft ends of a plurality of rollers 70R (shown in FIG. 1) and transfer rollers 5Y, 5M, 5C, and 5K. .

  In the overlapping unit frames 71 and 72, only 71 is shown in the figure, but positioning holes 73A and 73B as first positioning means are provided, respectively.

  Corresponding to the positioning holes 73A and 73B on the overlapping unit T side, positioning holes 80A and 80B as third positioning means are provided in the front frame 80, and through holes 81A and 81B are provided in the intermediate frame 81. Further, positioning pins 83A and 83B as first positioning pins are fixed to the rear frame 82 of the image forming apparatus main body corresponding to the positioning holes 73A and 73B on the overlapping unit side.

  The positioning pin 83A passes through the through hole 81A and fits into the positioning hole 73A (positioning means 73A of the superposition unit 72), and the positioning pin 83B penetrates the through hole 83B, and the positioning hole 73B (positioning means of the superposition unit 72) 73B).

  The positioning pins 83A and 83B have the shape shown in FIG. 7 and have a pin and a flange 833, the base portion 831 and the tip portion 832 of the pin have a diameter of micron order accuracy, and the base portion 831 has a positioning surface. Form. The positioning pins 83A and 83B are the same, and are denoted by 83 in FIG. FIG. 7A is a plan view of the positioning pin 83, and FIG. 7B is a cross-sectional view of the positioning pin 83.

  Screws for fixing the positioning pins 83A and 83B to the front frame 80 and the rear frame 82 are fitted into the grooves 834 provided in the flange 833.

  Position pins 83A and 83B are fixed in advance to the back frame 82, while positioning pins 83A and 83B are fixed to the front frame 80 when the overlapping unit T is attached to the drawer unit D. .

  That is, the overlapping unit T is assembled to the drawer unit D, the positioning hole 73A of the overlapping unit 72 of the overlapping unit T is aligned with the positioning hole 80A of the front frame 80, and the positioning hole 73B is aligned with the positioning hole 80B. Later, the positioning pin 83A is fitted into the positioning holes 73A and 80A, the positioning pin 83B is fitted into the positioning holes 73B and 80B, and each is fixed to the front frame 80.

Since these parts are processed so that the difference between the diameter of the positioning holes 73A, 73B, 80A, 80B and the outer diameter of the base 831 of the positioning pins 83A, 83B is 30 to 50 μm, the positioning pins 83A, 83B And the positioning holes 73A, 73B, 80A, 80B, the overlapping unit T is positioned with respect to the drawer unit D within an error range of several tens of microns.
<Fitting with interference fit>
As shown in FIG. 6, positioning unit 74A as a second positioning pin is provided at a second position close to the first position at which positioning holes 73A and 73B are provided in the overlapping unit frames 71 and 72 of the overlapping unit T. 74B is fixed. 6 shows the positioning pins 74A and 74B of the overlapping unit 71, the positioning unit 74 is also provided with positioning pins 74A and 74B.

  On the other hand, as shown in FIG. 6, a support member 84A as second positioning means is fixed to the intermediate frame 81 corresponding to the positioning pins 74A of the overlapping unit 7, and second positioning means corresponding to the positioning pins 74B. The support member 84B is fixed.

  As shown in FIG. 3, the front frame 80 is also provided with support members 84A and 84B as second positioning means. That is, the support member 84A is fixed corresponding to the positioning pin 74A on the overlapping unit side, and the support member 84B is fixed corresponding to the positioning pin 74B.

The support members 84A and 84B have the same shape. As shown by 84 in FIG. 8, a protrusion 843 that forms a support groove 842 is formed on the substrate 841, and a mounting screw is inserted into the substrate 841. A hole 844 is formed. FIG. 8 is a plan view of the support member 84. The support groove 842 is formed so that its inner diameter is several hundred microns larger than the outer diameter of the positioning pins 74A and 74B.

  When the positioning pins 74 </ b> A and 74 </ b> B are on the support groove 842, the overlapping unit T is supported by the front frame 80 and the intermediate frame 81.

  9 shows the cap member 85, FIG. 9A is a plan view, and FIG. 9B is a cross-sectional view. The cap member 85 includes a cylindrical portion 851 into which the positioning pins 74A and 74B are fitted, and a substrate 852. The substrate 852 is formed with a groove 853 into which a screw for fixing the cap member 85 to the front frame 80 and the intermediate frame 81 is fitted. Is done.

  The cap member 85 shown in FIG. 9 is inserted into the positioning pins 74A and 74B. The cap member 85 is a resin member and is supported by the support groove 842 of the support member 84 when the cap member 85 is interposed between the positioning pins 74A and 74B and the protrusion 843 in the inserted state. The positioning pins 74A and 74B are pushed upward.

  The pushing-up action of the cap member 85 pushes the overlapping unit T upward with respect to the drawer unit D and the image forming apparatus main body H, and the base portion 831 of the positioning pin 83 in FIG. It is positioned at a predetermined position determined by design with respect to 73B. As a result, the overlapping unit T is accurately positioned with respect to the front frame 80 and the rear frame 82.

  The action of such an interference fit will be described with reference to FIG.

  10, the pin PN is the base 831 of the pin 83 in FIG. 7, and the hole AP is the positioning holes 73A and 73B in FIG.

  As a result of the push-up action by the cap member 85 of FIG. 9, the pin is pushed in the XY direction in the hole AP and contacts the predetermined position of the hole AP, thereby positioning the pin PN.

In this way, the pin PN positioned by the gap fitting is positioned at a predetermined position in the hole AP by the interference fitting by the action of the cap member 85, and the overlapping unit T has a high positional accuracy and the drawer unit D and the image formation. It is positioned with respect to the apparatus main body H.
(2) Embodiment 2
FIG. 5 shows a color image forming apparatus according to another embodiment 2 of the present invention.

  The color image forming apparatus shown in the figure forms an image forming unit Y for forming a yellow toner image, an image forming unit M for forming a magenta toner image, an image forming unit C for forming a cyan toner image, and an image forming for forming a black toner image. It has a unit K. Each image forming unit includes a photosensitive member 1, a charging device 2, an exposure device 3, a developing device 4, a transfer device 5, and a cleaning device 6, which are respectively labeled Y, M, C, and K.

  Reference numeral 31 denotes a conveying belt as a conveying member that conveys the recording material P. The conveying belt 31 is stretched around the driving roller 31R1 and the driven roller 31R2, and is driven by the driving roller 31R1 to circulate and move as indicated by an arrow.

  The conveying belt 31, the driving roller 31R1, and the driven roller 31R2 are stacked to convey a recording material P carrying a multicolor toner image formed by superimposing single color toner images formed in the image forming units Y, M, C, and K. The alignment unit T is configured.

  The overlapping unit T and the image forming units Y, M, C, and K are coupled by gap fitting coupling and interference fitting coupling as in the first embodiment.

  The recording material P supplied from the storage unit 14 is brought into close contact with the conveying belt 31 by an electrostatic force or mechanically adhering means 32 and is conveyed by the conveying belt 31, and is stored in the image forming units Y, M, C, and K. A color toner image is formed on the recording material P through the transfer position. The formed color toner image is fixed by the fixing device 13.

The driving roller 31R1 is driven by a motor MT as driving roller driving means, and the shaft of the driven roller 31R2 is driven by a motor 23 as driven roller driving means.
(3) Embodiment 3
FIG. 6 shows a color image forming apparatus according to still another embodiment 3 of the present invention.

  Image forming portions Y, M, C, and K are disposed along a photosensitive belt 41 as an image carrier, and each image forming portion is a charging device 2 (Y, M, C, K) exposure device 3 (Y, M , C, K) and a developing device (Y, M, C, K) 4.

  Reference numeral 5 denotes a transfer device that transfers the color toner image on the photoreceptor 1 to the recording material P, 6 denotes a cleaning device that cleans the photoreceptor 1, and 24 denotes a fixing device that fixes the color toner image on the recording material P.

  On the photosensitive belt 41, a yellow toner image, a magenta toner image, a cyan toner image, and a black toner image are formed and superimposed to form a color toner image. The formed color toner image is transferred to the recording material P by the transfer device 5 and fixed by the fixing device 13.

  A driving roller 41R1 for driving the photosensitive belt 41 is driven by a motor MT and moves as indicated by an arrow to form an image.

  The photosensitive belt 41, the driving roller 41R, and the driven roller 41R2 constitute an overlapping unit 40, and the image forming units Y, MT, C, and K and the overlapping unit T are gap-fitting and tightening as in the first embodiment. It is connected by the fitting connection.

  The embodiment described above is a color image forming apparatus in which a multicolor toner image is formed by one circulation movement of the superposition unit, but the present invention is not limited to such a color image forming apparatus. That is, an image of a system in which a single color toner image is formed by one circulation movement of the superposition unit and a multicolor toner image is formed on an image carrier such as an intermediate transfer member or a photosensitive member by a plurality of circulation movements. The present invention can also be applied to a forming apparatus.

1 is a schematic configuration diagram of a color image forming apparatus according to Embodiment 1 of the present invention. FIG. 4 is a diagram illustrating a relationship among an image forming apparatus main body H, an overlapping unit T, and a drawer unit D as an image forming unit. FIG. 4 is a view showing a front frame 80 of the drawer unit D. FIG. 6 is a view showing an intermediate frame 81 of the drawer unit D. 3 is a view showing a back frame 82 of the image forming apparatus main body H. FIG. 2 is a perspective view of a superposition unit T. FIG. It is a figure which shows positioning pin 83A, 83B. It is a figure which shows support member 84A, 84B. It is a figure which shows the cap member 85. FIG. It is a figure for demonstrating the effect | action of interference fitting. It is a schematic block diagram of the color image forming apparatus which concerns on Embodiment 2 of this invention. It is a schematic block diagram of the color image forming apparatus which concerns on Embodiment 3 of this invention.

Explanation of symbols

D Drawer unit H Image forming apparatus main body T Overlapping unit 71, 72 Overlapping unit frame 80 Front frame 81 Intermediate frame 82 Rear frame 83, 83A, 83B Positioning pin 84, 84A, 84B Support member 85 Cap member 100 Image forming apparatus

Claims (13)

In an image forming apparatus having an image forming unit for forming a single color toner image and an overlapping unit for forming a multicolor toner image by superimposing the single color toner images formed in the image forming unit,
In the first position, the first positioning means and a first positioning pin that fits into the first positioning means with a gap are coupled with a gap.
In the second position, the second positioning means, the second positioning pin fitted into the second positioning means, and the interference fit coupling by the cap member interposed between the second positioning means and the second positioning pin,
An image forming apparatus, wherein the image forming unit and the superposition unit are combined. The image forming unit develops an image forming body, latent image forming means for forming an electrostatic latent image on the image forming body, and the formed electrostatic latent image to form a toner image on the image forming body. The image forming apparatus according to claim 1, further comprising: a developing unit, wherein the superimposing unit includes an intermediate transfer member that carries the toner image transferred from the image forming member. The image forming unit develops an image forming body, latent image forming means for forming an electrostatic latent image on the image forming body, and the formed electrostatic latent image to form a toner image on the image forming body. 2. The image forming apparatus according to claim 1, further comprising a developing unit, wherein the superimposing unit includes a recording material conveyance body that conveys a recording material carrying the toner image transferred from the image forming body. apparatus. The superposition unit has an image forming body, and the image forming unit develops a latent image forming means for forming an electrostatic latent image on the image forming body and a toner image by developing the formed electrostatic latent image. The image forming apparatus according to claim 1, further comprising a developing unit for forming the image forming apparatus. The superposition unit has a superposition unit frame provided with the first positioning means, and the image forming unit has a first image formation unit frame provided with a third positioning means, The image forming apparatus according to claim 1, wherein the gap fitting coupling is formed by inserting a positioning pin into the first and third positioning means. The second positioning pin is formed on the overlapping unit frame, the second positioning means is provided on the first image forming unit frame, and the cap member is inserted into the second positioning pin. The image forming apparatus according to claim 1. In an image forming apparatus having an image forming apparatus main body and an overlay unit,
In the first position, the first positioning means and a first positioning pin that fits into the first positioning means with a gap are coupled with a gap.
In the second position, the second positioning means, the second positioning pin fitted into the second positioning means, and the cap member interposed between the second positioning means and the second positioning pin are coupled with an interference fit. ,
An image forming apparatus, wherein the image forming apparatus main body and the superposition unit are combined. 8. The image forming apparatus main body includes a main body frame provided with the first positioning pins, and the superposition unit includes a superposition unit frame provided with the first positioning means. The image forming apparatus described in 1. An image forming unit that forms a toner image to be transferred to the superposition unit; and the superposition unit frame is provided with the second positioning pin, and the image forming unit is a second image forming unit. The image forming apparatus according to claim 8, further comprising: a frame, wherein the second image forming unit frame is provided with the second positioning unit. The image forming apparatus according to claim 1, wherein the first positioning unit includes a hole. The image forming apparatus according to claim 1, wherein the second positioning unit includes a groove. The image forming apparatus according to claim 5, wherein the third positioning unit includes a hole. An image forming unit for forming a toner image transferred to the superposition unit, and the image forming unit and the superposition unit are coupled by the gap fit coupling and the interference fit coupling. The image forming apparatus according to claim 7.

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