JP2003307894A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of securing the positional accuracy of an image forming part and made lightweight and inexpensive. <P>SOLUTION: The image forming part and a paper feeding part are arranged in separate housings, and also an image forming part housing 0 is installed on a paper feeding part housing 10, and further the rigidity of the housing 10 is set to be lower than that of the housing 0. Even if an installing place is rugged, the ruggedness is absorbed by the distortion of the low-rigidity housing 10 present under the housing 0, and the housing 0 present on the housing 10 is prevented from being largely deformed. Therefore, the image forming part in the housing 0 always keeps the high positional accuracy so as to prevent the deterioration of image quality caused by color slurring. The image forming apparatus is made lighter in weight than in the case the entire apparatus is constituted as the high-rigidity one, and also the reduction of cost is expected. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine or a printer, and more particularly, to a casing structure of an image forming apparatus capable of ensuring a positional accuracy of an image forming unit and preventing deterioration of image quality. It is a thing.

[0002]

2. Description of the Related Art In a tandem type image forming apparatus in which a plurality of photosensitive drums (for example, four responsible for yellow, magenta, cyan, and black) for forming images of different colors are arranged in series at equal intervals. For example, since the positional deviation between the respective photosensitive drums directly appears as the color deviation of the image, a high strength is required especially in the apparatus casing among various image forming apparatuses. Therefore, in the conventional tandem-type image forming apparatus, the entire apparatus housing is constructed by welding a pipe frame or sheet metal to enhance the strength of the apparatus housing and ensure the positional accuracy of the image forming unit arranged therein. The image quality was prevented from degrading due to color misregistration. Patent Document 1 is an example of such an image forming apparatus.

[0003]

[Patent Document 1] Japanese Patent Laid-Open No. 2001-34021

[0004]

However, if the entire apparatus casing is constructed by welding a high-strength pipe frame or sheet metal as described above, there is a problem that the apparatus becomes heavy and the cost becomes high. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an image forming apparatus that can secure positional accuracy of an image forming unit, and that is lightweight and low cost.

[0005]

In order to achieve the above object, the first invention is an image forming section including a photosensitive drum, a developing device and the like, and a sheet feeding section for conveying a transfer sheet to the image forming section. In the image forming apparatus comprising: the image forming unit and the paper feeding unit are arranged in separate housings, and the image forming unit housing is installed on the paper feeding unit housing; Further, the image forming apparatus is characterized in that the number of connecting members for connecting the side plates constituting the casing is smaller in the paper feeding unit casing than in the image forming unit casing. The rigidity is affected by the number of connecting members such as bolts that connect the side plates. The image forming section has more rigidity by increasing the number of connecting members. The second invention is
In an image forming apparatus including an image forming unit including a photosensitive drum, a developing device, and the like, and a paper feeding unit that conveys a transfer sheet to the image forming unit, the image forming unit and the paper feeding unit are separately provided. Of the image forming unit, the image forming unit casing is installed on the paper feeding unit casing, and the number of bridging members connecting the side plates that form the casing is different from that of the image forming unit casing. The image forming apparatus is characterized in that the paper feed unit housing is smaller than the body. The rigidity is affected by the number of bridging members such as stays that connect the side plates. The image forming section has more bridging members to improve the rigidity. A third aspect of the present invention is an image forming apparatus including an image forming unit including a photoconductor drum, a developing device, and the like, and a paper feeding unit that conveys transfer paper to the image forming unit. The paper feeding unit is arranged in a separate housing, the image forming housing is installed on the paper feeding housing, and the number of fastening points constituting the housing is the same as the image forming housing. The image forming apparatus is characterized in that the number of paper feed unit housings is smaller. The fastening points that make up the housing improve the rigidity of the housing. The image forming section has improved rigidity by increasing the number of fastening points. A fourth aspect of the present invention is an image forming apparatus including an image forming unit including a photosensitive drum, a developing device, and the like, and a paper feeding unit that conveys a transfer sheet to the image forming unit. With respect to the directionality of the connection member that arranges the paper feed unit in a separate housing, installs the image formation housing on the paper feed housing, and connects the side plates that form the housing. The image forming apparatus is characterized in that the paper feed unit casing has a smaller number of fastening directions than the image forming unit casing. Fastening is usually performed in a plurality of directions such as upward and leftward, downward and rightward and leftward. The greater the number of directions, the higher the rigidity. In this invention,
In view of this point, the paper feed unit has a smaller number of fastening directions. A fifth aspect of the present invention is an image forming apparatus including an image forming unit including a photoconductor drum, a developing device, and the like, and a sheet feeding unit that conveys a transfer sheet to the image forming unit. In addition to placing the paper feed unit in a separate housing,
The image forming unit casing is installed on the paper feeding unit casing, and further,
The image forming apparatus is characterized in that the side plates, stays, and other constituent members of the casing are made thinner in the sheet feeding unit casing than in the image forming unit casing. The plate thickness of the member directly affects the rigidity. The plate pressure of the constituent members of the paper feeding unit is reduced to reduce the rigidity. A sixth aspect of the present invention is an image forming apparatus including an image forming unit including a photosensitive drum, a developing device, and the like, and a paper feeding unit that conveys a transfer sheet to the image forming unit. The sheet feeding unit is arranged in a separate housing, the image forming unit housing is installed on the sheet feeding unit housing, and the reinforcing plate and the cross-sectional shape of the stay that form the housing are The image forming apparatus has a U-shape in the image forming unit housing and a flat plate in the paper feeding unit housing. The rigidity is determined by the sectional shape of the reinforcing plate or stay, which is a component of the housing, that is, the second moment of area. Therefore, the image forming section has a U-shaped cross section having a large second moment of area, and the sheet feeding section is formed in a flat plate shape having a small second moment of area, so that the rigidity can be made different. With such a configuration, even if there are irregularities in the installation location, the irregularities are absorbed by the distortion of the low-rigidity paper feed unit casing below the image forming unit casing, and The image forming unit housing is not greatly deformed. Therefore, the image forming unit in the image forming unit housing always maintains high positional accuracy, and the deterioration of image quality due to color misregistration can be prevented. In addition, the weight can be reduced and cost reduction can be expected compared with the case where the entire device is configured to have high rigidity.
In a so-called tandem-type image forming apparatus in which a plurality of photosensitive drums are arranged in series in the image forming unit casing, a final image is obtained by superimposing the images formed on the respective photosensitive drums. Therefore, the positional deviation of the image forming unit including the photosensitive drum directly causes the color deviation, which adversely affects the image quality. Therefore, it is considered to be particularly effective to apply the present invention capable of ensuring the positional accuracy of the image forming unit to such a tandem type image forming apparatus, but of course, the image forming apparatus having only one image forming unit. It is also effective when applied to.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments and examples of the present invention will be described below with reference to the accompanying drawings to provide an understanding of the present invention. The following embodiments and examples are examples of embodying the present invention, and do not limit the technical scope of the present invention. FIG. 1 is a schematic configuration diagram of a tandem type full color printer Z1 according to the embodiment of the present invention.

A tandem type full color printer Z1 according to the present embodiment has a schematic structure as shown in FIG.
The tandem type full color printer Z1 is provided with four sets of image forming units including a drum unit 1 (1a to 1d) centering on a photosensitive drum, an exposure unit 2 (2a to 2d), a developing unit 3 (3a to 3d), and the like. They are arranged in series at equal intervals and are in charge of image formation for each color of black, yellow, magenta, and cyan. Further, transfer rollers 4a to 4d arranged to face the drum units 1a to 1d, respectively.
An endless transfer belt 7 is wound around 4d, the driving roller 5, the driven roller 6, and the like.
Is rotated counterclockwise in FIG. 1 by the drive of the drive roller 5 to sequentially pass the transfer paper through the four image forming sections. The transfer rollers 4a to 4d, the driving roller 5, the driven roller 6, and the transfer belt 7 wound around them.
Are integrated as a transfer unit 8. here,
The four image forming units and the transfer unit 8 (an example of an image forming unit) are mounted in a box-shaped image forming unit housing 0.

Below the image forming unit housing 0, a sheet feeding housing 10 formed separately from the image forming unit housing 0 is installed, and both of them are, for example, detachably connected. There is. In the paper feed case 10, the transfer paper tray 11 and the paper feed roller 1 are provided.
2 and the like (an example of a paper feed unit) are provided. The two housings are connected to the side surfaces of the image forming unit housing 0 and the paper feeding unit housing 10, and transfer paper is transferred from the paper feeding unit housing 10 to the image forming unit housing 0. A transport unit 20 for transporting is detachably attached. Further, a paper discharge unit 30 is detachably attached to the downstream side of the image forming unit casing 0. A fixing unit 31, a paper discharge path 32, a paper discharge tray 33, and the like are provided in the paper discharge unit 30, and the transfer paper onto which the four color toner images have been transferred is transferred in the image forming unit housing 0. After the fixing process, the transfer paper is discharged onto the paper discharge tray 33.

Here, the image forming unit housing 0 is formed with high rigidity to such an extent that the positional accuracy of the image forming unit and the like installed therein can be maintained high. On the other hand, the rigidity of the paper feed case 10 installed as a base in the lower part is lower than that of the image forming case 0, and is kept at the minimum necessary strength. As a result, even if there is unevenness in the installation location, the unevenness is absorbed by the distortion of the paper feed unit housing 10 below the image forming unit housing 0, and the image creating unit housing 0 becomes large. It does not deform. Therefore, the image forming unit in the image forming unit housing 0 is always maintained with high positional accuracy, and for example, the distance or angle between the image forming units does not shift, and the image quality deterioration due to color misregistration can be prevented. Here, the image forming unit housing 0
As a specific method for increasing the rigidity of the paper feeding unit housing 10 and decreasing the rigidity of the paper feeding unit housing 10, for example, it is conceivable that members and configurations of both housings have the differences shown in the following table.

[Table 1]

For example, in the case of the image forming unit housing 0, in order to increase the rigidity, the members are made thicker by the side plates and edge-bent, and further strengthened by the reinforcing plates and stays. It is conceivable to form the cross section in a U shape. Further, regarding the configuration, it is conceivable that the number of connections between the side plates and the number of bridging members are increased, and that the bottom surface + 4 side surfaces are formed into a box shape. On the other hand, in order to reduce the rigidity of the paper feed unit housing 10, the side plate of the member is thinned and the bending of the side plate is not performed, and the reinforcing plate is also thinned to have a flat plate shape. It is possible to do it. In addition, regarding the configuration, it is conceivable that each side plate is made independent by reducing the connection between the side plates and the bridging member. Here, if the rigidity of the paper feed unit housing 10 is reduced by the above method, the paper feed unit housing 10 is consequently lightened and the cost is also kept low. Regarding the difference in rigidity between the image forming unit housing 0 and the paper feeding unit housing 10, the respective housings are placed or fixed on exactly the same test stand under exactly the same conditions (for example, at the same height). It can be confirmed by applying a load (at the position), measuring the strain, and comparing them. If the rigidity of the paper feed unit housing 10 is lower than that of the image forming unit housing 0, the distortion of the paper feed unit housing 10 should be measured more naturally.

As described above, in the tandem type full color printer Z1 according to the present embodiment, the image forming unit housing 0
Is formed with high rigidity such that the positional accuracy of the image forming unit and the like installed inside can be maintained at a high level, and the rigidity of the paper feed casing 10 installed below as a base of the image forming unit is Since it is lower than the case 0 and is kept at the minimum necessary strength, even if there is unevenness in the installation location, for example, the unevenness is at the bottom of the image forming case 0, and the paper feeding case is above. The body 10 is absorbed by being distorted, and the image forming unit housing 0 is not largely deformed. Therefore, the image forming unit in the image forming unit housing 0 always maintains high positional accuracy, and the deterioration of image quality due to color misregistration can be prevented. In addition, the weight can be reduced and cost reduction can be expected compared with the case where the entire device is configured to have high rigidity.

[0012]

EXAMPLE A tandem type image forming apparatus such as the tandem type full color printer Z1 according to the above embodiment,
A plurality of image forming units including a photoconductor drum are installed in series in the image forming unit, and the final image can be obtained by superimposing the images formed by the respective image forming units. The positional deviation is directly affected by the color deviation, which adversely affects the image quality. Therefore, it is considered to be particularly effective to apply the present invention capable of ensuring the positional accuracy of the image forming section to such a tandem type image forming apparatus, but of course, the image forming apparatus having only one image forming section. It goes without saying that it is effective even when applied to such as.

[0013]

As described above, the present invention is an image forming apparatus including an image forming section including a photosensitive drum, a developing device, and the like, and a sheet feeding section for conveying a transfer sheet to the image forming section. In the above, the image forming unit and the paper feeding unit are arranged in separate housings, and the image forming unit housing is installed on the paper feeding unit housing. Since the image forming apparatus is configured to have a specific configuration necessary for lowering the rigidity of the paper feed unit casing as compared with the rigidity, for example, even if the installation location has unevenness, the unevenness is The low-rigidity paper feed unit casing under the image forming unit casing is distorted and absorbed,
The image forming unit casing thereon does not significantly deform. Therefore, the image forming unit in the image forming unit housing always maintains high positional accuracy, and the deterioration of image quality due to color misregistration can be prevented. In addition, the weight can be reduced and cost reduction can be expected compared with the case where the entire device is configured to have high rigidity.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a tandem type full color printer Z1 according to an embodiment of the present invention.

[Explanation of symbols]

0 ... Imaging unit housing 1 (1a to 1d) ... drum unit 2 (2a to 2d) ... exposure device 3 (3a to 3d) ... Developing unit 4 (4a to 4d) ... Transfer roller 5 ... Drive roller 6 ... driven roller 7 ... Transfer belt 8 ... Transfer unit (above, an example of image forming unit) 10 ... Paper feed unit housing 11 ... Transfer paper tray 12 ... Paper feed roller (above, an example of paper feed unit)

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Claims (6)

[Claims] 1. An image forming apparatus comprising: an image forming unit including a photosensitive drum, a developing device, and the like; and a paper feeding unit that conveys a transfer sheet to the image forming unit. The paper unit is placed in a separate housing, the image forming unit housing is installed on the paper feeding unit housing, and the number of connecting members connecting side plates forming the housing is the same as the number of image forming members. An image forming apparatus characterized in that the number of paper feed unit casings is smaller than that of the unit casings. 2. An image forming apparatus comprising an image forming unit including a photosensitive drum, a developing device, etc., and a paper feeding unit for conveying transfer paper to the image forming unit. The paper unit is placed in a separate housing, the image forming unit housing is installed on the paper feeding unit housing, and the number of bridging members connecting the side plates that form the housing is different from each other. An image forming apparatus characterized in that there are fewer paper feed unit casings than image forming unit casings. 3. An image forming apparatus comprising an image forming section including a photosensitive drum, a developing device, etc., and a paper feeding section for conveying a transfer sheet to the image forming section. The paper unit is arranged in a separate housing, the image forming unit housing is installed on the paper feeding unit housing, and the number of fastening points forming the housing is greater than that of the image forming unit housing. An image forming apparatus characterized in that the number of paper feed unit housings is smaller. 4. An image forming apparatus comprising an image forming unit including a photosensitive drum, a developing device, and the like, and a paper feeding unit for conveying transfer paper to the image forming unit. The paper unit is arranged in a separate housing, the image forming housing is installed on the paper feeding housing, and the directionality of the connecting member that connects the side plates that form the housing, An image forming apparatus characterized in that a paper feed unit casing has a smaller number of fastening directions than an image forming unit casing. 5. An image forming apparatus comprising: an image forming unit including a photosensitive drum, a developing device, etc .; and a paper feeding unit for conveying a transfer sheet to the image forming unit. The paper unit is placed in a separate housing, the image forming housing is installed on the paper feeding housing, and the thickness of the side plates, stays, and other constituent members of the housing is The image forming apparatus is characterized in that the paper feed unit casing is thinner than the image forming unit casing. 6. An image forming apparatus comprising an image forming unit including a photosensitive drum, a developing device, and the like, and a paper feeding unit for conveying transfer paper to the image forming unit. The paper unit is placed in a separate housing, the image forming unit housing is installed on the paper feeding unit housing, and the reinforcing plate and the cross-sectional shape of the stay forming the housing are formed. The image forming apparatus is characterized in that the image housing has a U shape and the paper feeding housing has a flat plate shape.