JP3378711B2 - Image forming device - Google Patents

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 configured as a copying machine, a printer, a facsimile, or a multi-function machine combining these functions as appropriate.

[0002]

2. Description of the Related Art An image forming apparatus of the above type has an image carrier on which an electrostatic latent image is formed, a developing unit for visualizing the electrostatic latent image as a toner image, and a toner image transferred. It has various image forming units such as a pair of conveying rollers for conveying the recording paper and a fixing unit for fixing the toner image on the recording paper.Many of these image forming units are in front of the image forming apparatus main body. It is supported by a front side plate and a rear side plate which are arranged to face each other at a side and a back side with a space therebetween. The front side usually refers to the side of the image forming apparatus main body on which the operator is located, and the opposite side facing this is the back side.

Such image forming apparatuses are classified into various types according to their functions. For example, as described above, the image forming apparatus having only the function of the copying machine, the image forming apparatus having only the function of the printer, the image forming apparatus having only the facsimile function, or the image forming apparatus in which these functions are appropriately combined is used. There are various types such as a monochromatic image forming apparatus capable of obtaining only a monochromatic image and a color image forming apparatus capable of obtaining a multicolor image or a full color image. One way to reduce the cost of such various types of image forming apparatuses is to make the parts common. For example, the fixing device having the same structure is used for the single-color image forming apparatus and the color image forming apparatus to reduce the total cost.

By the way, the image forming unit used in these image forming apparatuses has an image forming unit having a unit element movable with respect to the unit body, and has such a unit element. There is an image forming unit in which the unit main body itself is movably supported with respect to the front side plate and the rear side plate of the image forming apparatus main body. For example, a developing unit used in a monochromatic image forming apparatus has a unit element composed of, for example, a developing roller that rotates with respect to the unit body, but the unit body itself is arranged immovably with respect to the image forming apparatus body. To be done. On the other hand, the rotary developing unit used in the color image forming apparatus is
Having a plurality of developing devices, each developing device is provided with a developing roller rotatable with respect to the unit main body,
The unit main body of the developing unit is rotatably supported by the front side plate and the rear side plate so that each developing device can be brought to a developing position facing the image carrier. At that time, the drive element for rotating the unit main body and the drive element for rotationally driving the developing roller are arranged on the back side of the unit main body and on the front side of the rear side plate. If these driving elements are arranged on the front side of the unit main body, when the operator performs maintenance work for the developing unit, the driving elements may interfere with the work or the operator may touch the driving elements. Is.

As described above, since the rotary developing unit is provided with a large number of drive elements for driving the unit main body and the unit elements on the inner side of the unit main body, the developing unit including the drive elements is provided. The entire length is longer than that of the developing unit of the monochrome image forming apparatus. Therefore, in order to support this long developing unit by the front side plate and the rear side plate, it is necessary to increase the distance between both side plates. That is, the distance between the front side plate and the rear side plate of the color image forming apparatus is larger than the distance between the front side plate and the rear side plate of the single image forming apparatus. Therefore, for the image forming units other than the developing unit in the color image forming apparatus and the single color image forming apparatus, it is necessary to prepare a unit of another form according to the distance between both side plates. For example, a fixing unit for a color image forming apparatus and a fixing unit for a single color image forming apparatus having a shorter length than this are separately manufactured, and each of them is provided with front and rear side plates of a main body of the color image forming apparatus with large intervals. , The front and rear side plates of the main body of the single-color image forming apparatus with a small interval. As can be seen from the above, it is not possible to share the components of the fixing unit between the color image forming apparatus and the monochromatic image forming apparatus, which inevitably leads to the drawback of increased cost. Such a phenomenon occurs not only between the color image forming apparatus and the single color image forming apparatus but also in the image forming unit other than the fixing unit.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image forming apparatus in which the above-mentioned conventional drawbacks are eliminated by a simple structure.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a front side plate and a rear side plate which are arranged on the front side and the rear side of an image forming apparatus body so as to be opposed to each other with a space therebetween, and these side plates. And an image forming unit movably supported in the image forming unit, the image forming unit having a unit element movable with respect to the unit main body, and the unit main body and the unit element being on the inner side of the unit main body. In the image forming apparatus that is respectively actuated via the drive elements arranged in the region on the front side of the rear plate, the rear plate is
An image forming apparatus is proposed in which at least a portion facing the rear end of the unit main body is formed so as to be recessed toward the rear side of the image forming apparatus main body.

At this time, the rear end of the unit body is opposed to the rear end of the pair of conveying rollers for conveying the recording paper rotatably supported by the front and rear plates. It is advantageous that the portion of the rear side plate facing to is formed by drawing so as to be recessed toward the back side of the image forming apparatus main body.

In each of the above constructions, the image forming unit is a developing unit for forming a toner image on the surface of the image carrier supported by the front side plate and the rear side plate, and the rear end portion of the image carrier. It is advantageous that the portion of the rear plate facing the rear end of the unit main body of the developing unit is formed so as to be recessed toward the rear side of the image forming apparatus main body with respect to the rear side plate of the developing unit. Is.

Similarly, in each of the above-mentioned constitutions, the image forming unit is a developing unit for forming a toner image on the surface of the image carrier supported by the front side plate and the rear side plate, and the rear side end of the image carrier. The portion of the rear side plate facing the image forming unit and the portion of the rear side plate facing the rear side end of the unit main body of the developing unit are both formed so as to be recessed toward the rear side of the image forming apparatus main body. And is advantageous.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows the inside of the printer section of the color image forming apparatus, which is the front side (front side) where the operator is usually located.
It is a schematic sectional drawing when it sees from.

In FIG. 1, a drum-shaped photoconductor 5 which is an example of the structure of the image carrier is rotationally driven counterclockwise in FIG. 1 by a drive motor (not shown). During this rotation, the surface of the photoconductor 5 is uniformly charged by the action of the charging charger 6 which is an example of a charging device. Next, in the exposure unit 7, a laser beam 9 emitted from the laser beam writing system 8 performs optical writing scanning, so that a predetermined electrostatic latent image is formed on the photoconductor 5. It is also possible to form the light image from the original directly on the photoconductor to form an electrostatic latent image.

The electrostatic latent image is first converted into a black toner image by a black developing device 40B of a rotary developing unit 13 having a black developing device 40B, a yellow developing device 40Y, a magenta developing device 40M, and a cyan developing device 40C. Visualized. In the illustrated image forming apparatus, an intermediate transfer belt 14 is provided so as to face the photoconductor 5, and the belt 14
Is rotated clockwise in FIG. 1, and the black toner image is primarily transferred to the intermediate transfer belt 14 in the primary transfer area 11 by the action of the transfer charger 15. The intermediate transfer belt 14 is wound around rollers 35, 36, 37, 38, 39 and driven to rotate.

After the above-mentioned formation of the electrostatic latent image, another color-separated electrostatic latent image is sequentially formed on the photoconductor 5 which continues to rotate. Each time the electrostatic latent image is formed, another developing device 4 of the rotary developing unit 13
0Y, 40M, 40C, yellow, magenta,
Cyan toner images are sequentially formed. Then, the toner images of the respective colors are sequentially superposed and secondarily transferred onto the initially transferred black toner image, so that a full-color toner image is formed on the intermediate transfer belt 14. After the toner images of the respective colors on the photoconductor 5 are transferred to the intermediate transfer belt 14, the toner remaining on the photoconductor 5 is cleaned and removed from the photoconductor 5 by the cleaning device 31.

On the other hand, the recording paper 17 is fed from the paper feed tray 16.
However, when the paper feed roller 19 rotates, the paper is fed toward the registration roller pair 18 via the conveyance roller pair 20. The recording paper 17 whose front end has reached the registration roller pair 18 is rotated by the registration roller pair 18 to cause the intermediate transfer belt 1 to rotate.
The front end portion of the full-color toner image on the recording sheet 4 and the front end portion of the recording paper 17 are sent toward the secondary transfer area 12 so as to meet the transfer area 12 in a favorable manner. in this way,
The registration roller pair 18 also constitutes a conveyance roller pair for conveying the recording paper.

The full-color toner image on the intermediate transfer belt 14 is secondarily transferred to the recording paper 17 sent toward the secondary transfer area 12 by the action of the transfer charger 21. After this transfer, the recording paper 17 is separated by the separation charger 2
By the action of 2, it is separated from the intermediate transfer belt 14.

The conveyor belt 23 includes a pair of rollers 23A,
It is hung between 23B and is rotationally driven in the counterclockwise direction in the figure. The recording paper 17 separated from the intermediate transfer belt 14 is sent toward the fixing roller pair of the fixing unit 24 by the rotation of the conveying belt 23.

The fixing roller pair includes a heat fixing roller 24A,
The heat fixing roller 24A, which is in pressure contact with the pressure roller 24B, is rotationally driven in the arrow direction in the figure, and the pressure roller 24B is also rotationally driven in the arrow direction.
While the recording paper 17 passes between these rotating rollers,
The transferred toner image on the recording paper is fixed. After this fixing, the recording paper is conveyed toward the paper ejection tray 27 by the rotation of the conveyance roller pair 25 and the ejection conveyance roller pair 26, and is stored in the tray 27 as a full-color copy paper.

A cleaning device 32 for the intermediate transfer belt is provided opposite to the intermediate transfer belt 14, and the toner remaining on the intermediate transfer belt 14 after the toner image is secondarily transferred from the intermediate transfer belt 14 to the recording paper 17 is generated. Cleaning is performed by the cleaning member 32 a of the cleaning device 32. The collected toner is collected in the cleaning device 3
The toner conveying member composed of the second toner conveying screw 33 conveys and discharges the toner to the outside of the case of the cleaning device. The cleaning member 32a is configured to be separated from the intermediate transfer belt 14 at a time other than the time of cleaning the intermediate transfer belt 14 so as not to disturb the toner image on the intermediate transfer belt 14.

In the case of a single color copy, the toner images of a plurality of colors are not superposed and transferred, but the single color toner images are transferred from the photoconductor 5 to the intermediate transfer belt 14, and the intermediate transfer belt 1 is further transferred.
The transfer toner image on the recording sheet 4 is transferred onto the recording paper, and the monochromatic copy paper is ejected to the paper ejection tray 27.

Here, the rotary type developing unit 13 briefly described above has a unit case 41 constituting its unit main body, and the unit case 41 is a developer for each of the developing devices 40B, 40Y, 40M and 40C. The room is partitioned. Each developer chamber contains a two-component developer having a toner of a predetermined color and a carrier, but a one-component developer containing no carrier may be used.

Developing units 40B, 40Y, 40M, 40C
Have the same structure except that they are radially arranged around the central axis O of the developing unit 13, and therefore only the black developing device 40B will be described as a representative thereof.
0B includes a developing roller 42B rotatably supported by the unit case 41, a stirring screw 43B that stirs while conveying the developer, and a stirring paddle 44B that also stirs and conveys the developer. 43B
The developer agitated by the agitating paddle 44B is supplied onto the developing roller 42B rotating clockwise in FIG. The supplied developer is carried while being carried on the developing roller 42B, and in the developing area between the developing roller 42B and the photoconductor 5, the electrostatic latent image formed on the photoconductor 5 is formed as described above. It is visualized as a black toner image.

Next, the unit case 41 of the developing unit 13 is rotationally driven in the clockwise direction in FIG. 1 around the central axis O thereof. As a result, the black developing device 40B, which has been occupying the developing position facing the photoconductor 5 until now, is separated from the developing position, and the next yellow developing device 40Y occupies the developing position. 5
The electrostatic latent image formed on the above is visualized as a yellow toner image. Similarly, the developing device 40C sequentially occupies the developing position of the magenta developing device 40M and the shear, and visualizes each electrostatic latent image as a magenta toner image and a cyan toner image.

FIG. 2 is a schematic plan view showing a state in which the rotary developing unit 13 and the photoconductor 5 are supported by the image forming apparatus main body 1. In this figure, the symbol A side is the front side of the image forming apparatus main body 1, the symbol B side is the rear side, and as described above, the operator is usually the front side of the image forming apparatus main body 1. Perform a predetermined operation. That is, the side on which the operator normally operates is the front side, and the opposite side facing this is the back side. As shown schematically in FIG. 3, the image forming apparatus main body 1 has a front side plate 46 and a rear side plate 47, which are arranged on the front side A and the rear side B of the main body 1 so as to face each other with a space therebetween and substantially parallel to each other. The lower end portions of the side plates 46 and 47 are fixed to a common bottom plate 48. The side plates 46 and 47 and the bottom plate 48 are made of, for example, a metal plate having high rigidity, and these form a frame of the image forming apparatus main body 1.

The reference numeral 49 in FIG. 2 is a unit carrier, and the carrier 49 is located so as to surround a part of the unit case 41, which is only schematically shown in FIG. 50 and a front support plate 51 fixed to the front end of the front support plate 51.
6 is inserted into the rear side through a hole 52 formed in 6, and the end portion on the rear side is removably positioned and supported with respect to the rear side plate 47 via a positioning pin (not shown). The front support plate 51 is detachably fixed to the front side plate 46 by a screw 53, and the unit case 41 of the rotary developing unit 13 is inserted into the rear side through a hole 54 formed in the front support plate 51. A unit support hole 56 in which a central shaft 55 projecting from the rear end of 41 is formed in the rear plate 47.
Is rotatably fitted to. The central axis 55 is located on the central axis O of the unit case 41. The front end of the unit case 41 is rotatably supported by a support roller 57 that is rotatably supported around the hole 54 of the front support plate 51. As described above, in the rotary developing unit 13, the front side of the unit case 41 is rotatably supported by the front side plate 46 via the unit carrying base 49, and the back side is rotatably supported by the rear side plate 47 by the central shaft 55. Has been done.

The unit carrier 49 is supported by front and rear plates 46 and 47 slidably in the front-rear direction via guide rails (not shown). Therefore, screw 5
By removing 3 and sliding the unit carrier 49 together with the developing unit 13 to the front side, the developing unit 13 can be pulled out to the front side of the image forming apparatus main body 1 or pushed to the back side thereof.

In the vicinity of the rear end of the unit case 41,
A unit rotating gear 58 is formed integrally with the case 41. The gear 58 is formed around the central axis O of the unit case 41 and meshes with a drive gear 60 that is rotationally driven by a drive motor 59 fixed to the rear side plate 47. By the operation of the drive motor 59, the rotation of the drive motor 59 is transmitted via the drive gear 60 to the unit rotation gear 58.
The rotary developing unit 13, that is, the unit case 41 thereof is driven to rotate in the clockwise direction in FIG. 1 around the central axis O, and the developing units 40B, 40Y, 40M and 40C are selected as described above. Is brought to the developing position.

Further, another drive motor 61 is fixed to the rear side plate 47, and the other drive gear 62 is rotationally driven by this motor 61. Further, as described above, each of the developing devices 40B, 40Y, 40M, and 40C is provided with the developing roller, the stirring screw, and the stirring paddle, but the shafts of these members extend from the rear end wall of the unit case 41. Further, input gears (not shown) are fixed to the portions further projecting toward the inner side, and the respective input gears of the developing device brought to the developing position are connected to the above-mentioned drive gear 62,
It is rotationally driven via an idle gear (not shown) supported at the rear end of the unit case 41, and the stirring screw, stirring paddle, and developing roller are rotationally driven as described above.

The above-described unit rotating gear 58, each input gear, idle gear, and both drive gears 60, 62 are arranged on the inner side of the unit case 41 and on the front side of the rear side plate 47. Has been done.

On the other hand, the photosensitive member 5 located opposite to the rotary developing unit 13 has a photosensitive member main body 63 formed in a cylindrical shape as shown in FIG. 2, and a rear end portion and a front end portion thereof. Disc-shaped support plates 64 and 65 that are fitted to each other are provided, and the support plates 64 and 65 are detachably fixed to the drive shaft 66. The photoconductor body 63 is arranged concentrically with the drive shaft 66,
The rear end of the drive shaft 66 is rotatably supported by a photoconductor support hole 84 formed in the rear plate 47 via a holder 67 and bearings 68, 68 held by the holder 67. The front end of the drive shaft 66 is rotatably supported via a bearing 71 in a hole of an auxiliary support plate 70 that is detachably fixed to the front plate 47. The auxiliary support plate 70 is
It is arranged so as to cover the hole 69 formed in the front side plate 46. The rear end of the drive shaft 66 extends through the rear plate 47, and the drive gear 7 is provided at the rear end of the rear plate 47.
2 is fixed. By driving the gear 72 by the drive motor (not shown), the photoconductor 5 is rotationally driven in the counterclockwise direction in FIG. As described above, the photoconductor 5 includes the drive shaft 66, the holder 63, the bearing 68,
It is rotatably supported by the front side plate 46 and the rear side plate 47 via 71 and the auxiliary support plate 70.

As described above, the image forming apparatus shown in FIG. 1 has a large number of conveying roller pairs for conveying the recording paper, and these roller pairs also include the front side plate 46 and the rear side plate 47 of the image forming apparatus main body 1. It is rotatably supported by. FIG. 4A is a sectional view showing a support structure of the registration roller pair 18 as an example. As shown in this figure, the registration roller pair 18 includes a driving roller 75 fixed to a driving roller shaft 73 and a driven roller shaft 74 which are arranged in parallel with each other.
And the driven roller 76. The front and rear ends of the roller shafts 73 and 74 are respectively bearings 77 and 7.
It is rotatably supported by the front side plate 46 and the rear side plate 47 via 8, 79 and 80. Gears 81 and 82 meshing with each other are fixed to the respective roller shaft ends on the inner side of the rear plate 47, and the gear 81 fixed to the drive roller shaft 73.
Is driven to rotate by a drive motor (not shown), whereby both rollers 75 and 76 are driven to rotate respectively, and as a result, the recording paper is transferred to the secondary transfer area 1 as described above.
2 (FIG. 1). Reference numeral 8 in FIG.
In FIG. 3, the driven roller shaft 74 is connected to the drive roller shaft 73.
It is a pressure spring that urges the rollers 75 and 76 toward each other, whereby the rollers 75 and 76 are pressed against each other at a predetermined pressure.

In the image forming apparatus described above, the rotary developing unit 13 constitutes an image forming unit which is rotatably supported by the front side plate 46 and the rear side plate 47 in this example. The image forming unit has a unit element composed of a developing roller, a stirring screw, and a stirring paddle that are movable with respect to a unit case 41 that is the unit body, and are rotatably supported in this example. The unit main body, that is, the unit case 41, and the unit element are drive elements, that is, the drive gear 60 and the unit, which are arranged in a region on the back side of the unit main body and on the front side of the rear plate 47. It operates through the rotating gear 58, the drive gear 62, the input gear, and the idle gear,
That is, it is rotationally driven. In this way, since the drive elements are arranged on the back side of the unit case 41,
When the operator performs maintenance work on the developing unit 13 on the front side of the image forming apparatus main body 1, each drive element does not interfere with the work, and the operator does not have to touch the drive element. it can.

When the drive element is located on the back side of the unit case 41 in this way, the length in the central axis direction of the entire developing unit 13 including the drive element is the development used in the monochromatic image forming apparatus. It will be longer than the length of the unit. Even in the developing unit of the single-color image forming apparatus, a driving element that rotationally drives a unit element such as a developing roller is required, but since it is not necessary to rotationally drive the entire unit, the driving element arranged on the back side thereof. The space occupied by can be kept small and its total length becomes short.

Therefore, conventionally, it is necessary to set the distance between both side plates of the color image forming apparatus larger than the distance between the front side plate and the rear side plate in the single color image forming apparatus (see FIG. 4B). This made it difficult to standardize parts. For example, the fixing unit 24 shown in FIG.
Also, the other image forming units also include a front side plate 46 and a rear side plate 47.
However, since the distance between the both side plates is longer in the color image forming apparatus than in the single color image forming apparatus, the length of the fixing unit in the front-rear direction is adjusted to the distance between the side plates. Since it is necessary to set the color image forming apparatus and the single-color image forming apparatus, it is impossible to use the same fixing unit, and it is difficult to share the parts.

Therefore, in the image forming apparatus of this example,
As clearly shown in FIGS. 2, 3, 5, and 6, at least the portion 47A of the rear plate 47 facing the rear end of the unit main body including the unit case 41 is the rear side B of the image forming apparatus main body. Is formed so as to be depressed. In this example, only the rear side plate portion 47A facing the rear end portion of the unit case 41 is recessed and formed in the rear side by, for example, δ = 10 mm (FIG. 5) from the other rear side plate portion 47A. There is.

According to this structure, the unit case 41 having the drive element on the back side can be housed in the main body of the image forming apparatus without any trouble, and the other image forming unit, for example, the fixing unit 24, is a monochromatic image. Since it is possible to support the front side plate 46 and the rear side plate 47 arranged at the same intervals as the forming device, the fixing unit 24 of the same form can be shared by the single color image forming device and the color image forming device. In this way, the total cost of the image forming apparatus can be reduced without any trouble. Further, as for the bottom plate 48 shown in FIG. 3 and the like, a bottom plate having the same form as this can be used in the single-color image forming apparatus, and parts can be shared.

In the portion of the rear side plate facing the rear end of the unit case 41 shown in FIG.
A large hole into which the rear end of the unit case 41 can be inserted, the rear end of the unit case 41 is inserted therein, the drive gears 60 and 62 are rotatably supported, and each drive motor 5
Even if the bracket that supports 9, 61 is fixed to the rear plate,
The space between the front side plate 67 and the rear side plate 47 can be narrowed, and other image forming units can be shared with the single color image forming apparatus. However, if a large hole is formed in the rear side plate, its strength is lowered, and if a bracket is provided, the cost is increased accordingly.

On the other hand, when a part of the rear side plate 47 is formed by drawing like the present example, it is not necessary to form a large hole in the rear side plate 47, so that the strength of the rear side plate 47 is lowered and the cost is reduced. Is not likely to rise. Not only that, when the recessed portion formed by drawing is formed in the rear side plate 47, the rigidity of the rear side plate 47 can be increased as compared with the case where this is not formed, and even if the thickness of the rear side plate 47 is set smaller than the conventional thickness. The predetermined rigidity can be maintained. As a result, cost reduction and weight reduction of the image forming apparatus can be achieved.

FIG. 4B is a sectional view showing the support structure of the registration roller pair 18 in the conventional color image forming apparatus. As shown in this figure, the front and rear side plates 4 are conventionally used.
The interval of 6, 47 had to be made larger than that of the image forming apparatus of this example shown in FIG. 3A. However, according to such a conventional configuration, the recording paper 17 with respect to the conveyance direction is conveyed. From the center CL in the width direction, the front side plate 46 and the rear side plate 47
The respective distances L1 and L2 up to are different from each other.
For this reason, the conveyance force that the recording paper 17 receives from the registration roller pair 18 is different between the left and right in the conveyance direction, which causes skew in the recording paper 17,
Transport problems such as jams are more likely to occur. The same applies to other pairs of conveying rollers.

On the other hand, in the image forming apparatus of this embodiment, as described above, the portion 47A of the rear side plate 47 facing the rear end of the unit case 41 in the developing unit 13.
However, the rear plate 47 facing the rear end of the registration roller pair 18 is not recessed (FIG. 4A). That is, the rear side plate 47 opposed to the rear side end portion of the pair of conveying rollers for conveying the recording paper (the registration roller pair 18 in the example of FIG. 4A) rotatably supported by the front side plate 46 and the rear side plate 47. A portion 47A (FIG. 2) of the rear plate 47 facing the rear end of the unit main body including the unit case 41 is formed so as to be recessed into the rear side B of the image forming apparatus main body. -ing

With this configuration, as described above, not only the advantage that the pair of conveying rollers including the pair of registration rollers 18 and the roller shaft thereof can be shared with the pair of conveying rollers of the single-color image forming apparatus, but also in FIG. Recording paper 1 shown in (a) of
The distances L1 'and L2' from the center CL of the conveyance direction 7 to the side plates 46 and 47 can be made equal. This makes it possible to apply an equal lateral conveyance force to the recording paper 17, suppress the occurrence of skew thereof, and prevent the conveyance trouble of the recording paper.

In the example shown in FIG. 2, as described above,
The image forming unit is configured as the developing unit 13 that forms a toner image on the surface of the photoconductor 5, which is an example of an image carrier supported by the front side plate 46 and the rear side plate 47, and the back side of the photoconductor 5 is formed. The part of the rear side plate 47 facing the end is not recessed on the back side. That is, the unit main body of the developing unit 13, that is, the unit case 4 with respect to the portion of the rear plate 47 facing the rear end of the photoconductor 5.
A portion 47A of the rear side plate 47 facing the rear end portion of 1 is formed so as to be recessed into the rear side B of the image forming apparatus main body 1.

With this structure, as described above, in addition to the advantage that the photoconductor 5 can be shared with the photoconductor of the monochromatic image forming apparatus, the following operational effects can be obtained.

If the rear plate 47 facing the rear end of the photoconductor 5 is also recessed toward the back of the image forming apparatus main body 1, the photoconductor 5 is formed on both side plates 46, 47. The distance between the supporting portions that support each other becomes long. That is, the distance between both bearings 68 and 74 becomes larger than that in the case of FIG. When the distance between the support portions of the photoconductor 5 is increased in this way, when the photoconductor 5 is rotationally driven, uneven rotation tends to occur with respect to the photoconductor 5. Even if the peripheral surface of the photoconductor 5 has a very slight eccentricity, the influence thereof is greatly exerted, and uneven rotation of the photoconductor 5 occurs. If such unevenness occurs, the toner image formed on the surface thereof may be blurred and the image quality thereof may be deteriorated. In order to prevent such uneven rotation of the photoconductor 5, it is sufficient to increase the support rigidity, but this increases the cost of the support structure.

On the other hand, in the example shown in FIG. 3, the portion of the rear side plate 47 facing the end portion on the back side of the photoconductor 5 is not formed to be recessed on the back side. Bearing 6
It is not necessary to increase the distance between 8 and 71. Therefore, when the photoconductor 5 rotates, it is possible to prevent the problem that the photoconductor 5 is unevenly rotated, and it is possible to prevent the toner image from blurring and improve the image quality. Further, it is possible to suppress an increase in cost for the support structure of the photoconductor.

On the other hand, in the embodiment shown in FIGS. 7 to 9, the front side plate 46 and the rear side plate 47 are movably supported and have a unit element movable with respect to the unit body. The image forming unit includes a front side plate 46 and a rear side plate 4.
Although the rotary developing unit 13 forms a toner image on the surface of the image carrier composed of the photoconductor 5 supported by the image carrier 7, the image carrier composed of the photoconductor 5 is the same as in the previous embodiment. A portion 47B of the rear plate 47 facing the back end of the body
Also, this is different from the previous embodiment in that the image forming apparatus main body 1 is recessed in the back side B. That is, the portion 47B of the rear plate facing the rear end of the image carrier and the portion 47A of the rear plate 47 facing the rear end of the unit case 41 (that is, the unit main body) of the developing unit 13, Both are formed so as to be recessed into the back side B of the image forming apparatus main body 1. Other configurations are
There is no difference from the example embodiments shown in FIGS.

According to the structure shown in FIGS. 7 to 9, as described above, the distance between the supporting portions for supporting the photoconductor 5 with respect to the both side plates 46, 47, that is, both bearings 68, 71.
(FIG. 2) Since the distance between them becomes large, it is necessary to increase the support rigidity of the photoconductor 5 in order to prevent rotation unevenness during rotation, which may increase the cost. It is possible to exert the excellent action and effect shown in.

As described above, in the unit case 41 of the developing unit 13, the central shaft 55 projecting from the rear end of the unit case 41 is fitted into the unit support hole 56 formed in the rear plate 47. The rear side is rotatably supported by the rear plate 47. Similarly, the rear side of the photoconductor 5 is fitted to the photoconductor supporting hole 84 formed in the rear plate 47 via the holder 67 and the bearing 68 so that the rear side of the drive shaft 66 is rearward. It is rotatably supported by the side plate 47. Both support holes 5 formed in the rear side plate 47 in this way
Reference numerals 6 and 84 determine the positions of the developing unit 13 and the photoconductor 5. To correctly determine the positions of both, it is necessary to properly position both support holes 56 and 84 and form them in the rear plate 47. is there.

Here, in the embodiment shown in FIGS. 7 to 9, since both parts 47A, 47B of the rear side plate are both recessed inward, these parts 47A, 47B are flush with each other. Located on top. The unit support hole 56 and the photoconductor support hole 84 are formed in the same plane, respectively. With such a configuration, both support holes 5 can be easily formed.
The center-to-center distances of 6 and 84 are correctly determined, so that the developing unit 13 and the photoconductor 5 can be correctly positioned. That is, when the rear side plate 47 shown in FIGS. 7 to 9 is formed, for example, the support holes 56 and 84 are first processed in the material of the flat plate-shaped rear side plate, and then the portions 47A and 47B are formed.
The distance between the centers of the two support holes 56 and 84 can be accurately determined by simply drawing together.

On the other hand, as shown in FIGS. 2 to 6, when the rear side plate 47 in which only the portion 47A of the rear side plate 47 is recessed is formed by the above-described method, both support holes 5 are formed.
The center-to-center distances of 6, 84 may be inaccurate due to variations in processing. That is, if both support holes 56 and 84 are first processed into a flat plate-shaped material and then only the portion 47A is formed by drawing, the two support holes 56 and 84 are
The stepped portion 85 shown in FIG. 2 and FIG. 5 is formed. Therefore, the center distance between the support holes 56 and 84 varies due to the return deformation after molding, which is inaccurate. It may be As a result, the relative position between the developing unit 13 and the photoconductor 5 becomes inaccurate, which may deteriorate the image quality of the toner image formed on the photoconductor.

Therefore, in order to manufacture the rear side plate 47 shown in FIG. 2, for example, a photosensitive material support hole 84 is first processed in a flat plate-shaped material, and then the portion 47A is subjected to draw forming. The unit support hole 56 must be processed to obtain the rear side plate 47, and thereby the positional accuracy of both support holes 56 and 84 must be improved. However, according to this processing method, three steps are required, which increases the manufacturing cost.

On the other hand, the rear side plate 47 shown in FIGS. 7 to 9 can obtain the rear side plate 47 with high positional accuracy of both the support holes 56 and 84 in the two steps as described above, and manufacture thereof. The cost can be effectively reduced.

Further, as shown in FIG. 2, when only the rear plate portion 47A facing the rear end of the unit case 41 is recessed in the rear side, the recessed portion is located adjacent to the step 85. Holder 6 for supporting the drive shaft 66 of the photoconductor 5
7 and the bearing 68 need to be arranged, but this holder 67
The drive shaft 6 in order to arrange the shaft without interfering with the stepped portion 85.
6 must be relatively far from the step 85. This means that the drive shaft 66 is largely separated from the developing unit 13. However, in this case, in order to arrange the surface of the photosensitive member 5 and the developing unit 13 in a predetermined positional relationship, the diameter of the photosensitive member 5 is reduced. Must be set to a large value, which inevitably leads to an increase in size of the image forming apparatus and an increase in cost.

On the other hand, in the configuration example shown in FIG. 7, the portion 47B of the rear side plate 47 on which the holder 67 is provided is flush with the portion 47A of the rear side plate 47 facing the rear end of the unit case 41. Therefore, no step is formed between the two. Therefore, it is not necessary to consider that the holder 67 interferes with the step portion, and the holder 67, and thus the drive shaft 66, can be freely brought closer to the developing unit 13. As a result, it is not necessary to set the diameter of the photoconductor 5 larger than necessary, and it is possible to reduce the size of the image forming apparatus and reduce its cost. As described above, the configurations shown in FIGS. 7 to 9 have unique effects not seen in the configurations shown in FIGS. 2 to 6, and conversely, the configurations shown in FIGS. Therefore, it is possible to achieve the above-mentioned excellent operational effects that are not found in the configuration shown in FIG.

As described above, the rotary developing unit 13 has been mentioned as an image forming unit which is movably supported by the front and rear side plates 46 and 47 and has a unit element movable with respect to the unit main body. The present invention can be applied to an image forming apparatus using another one. For example, as shown in FIG.
0B, 140Y, 140M, 140C, the unit case 141 of which is supported by the slide type developing unit 113 movably supported in the direction W orthogonal to the axial direction of the photoconductor 5 of the image forming unit. Other examples can be given.

The developing unit 113, when forming a black toner image on the photoreceptor 5, as shown in FIG.
40B faces the photoconductor 5, and the developing roller 142B rotates to carry and convey the black developer. Similarly, when forming a yellow toner image on the photoconductor 5, the unit main body including the unit case 141 moves to the left in the drawing, the yellow developing device 140Y faces the photoconductor 5, and the developing roller 142Y moves Rotate to execute the developing operation. The other two developing units 140M and 140C also perform the developing operation in the same manner. As described above, the developing unit 113 also has a unit element including a developing roller that is movably supported by the front side plate and the rear side plate of the image forming apparatus main body and is movable with respect to the unit main body. Such developing unit 11
Also for the image forming apparatus having No. 3, it is possible to adopt the above-mentioned respective configurations without any trouble, and to obtain the same operational effect as the above-mentioned place.

[0058]

According to the image forming apparatus of the first aspect, it is possible to achieve commonality of parts among image forming apparatuses of different types and reduce the total cost.

According to the image forming apparatus of the second aspect,
It is possible to suppress the trouble of conveying the recording paper.

According to the image forming apparatus of the third aspect,
Rotational unevenness of the image carrier can be easily suppressed, and the image quality can be improved.

According to the image forming apparatus of the fourth aspect,
The relative positional accuracy between the developing unit and the image carrier can be increased at low cost.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing a specific configuration of an image forming apparatus.

FIG. 2 is a schematic sectional plan view showing a relative positional relationship between a developing unit and a photoconductor.

FIG. 3 is a cross-sectional explanatory view showing a relative positional relationship between a front side plate, a rear side plate, and a developing unit.

FIG. 4 is a cross-sectional view showing a support structure of a registration roller.

FIG. 5 is a plan view illustrating relative positions of a front side plate, a rear side plate, a developing unit, and a photoconductor.

FIG. 6 is a diagram illustrating a form of a recessed portion formed on a rear side plate.

FIG. 7 is a plan view similar to FIG. 2, showing another embodiment example.

FIG. 8 is a view similar to FIG. 5 according to another embodiment.

FIG. 9 is a view similar to FIG. 6 in another embodiment example.

FIG. 10 is a schematic cross-sectional explanatory view showing another example of the developing unit.

[Explanation of symbols]

1 Image forming device body 13 Development unit 46 front plate 47 Rear plate 47A part 47B part 113 Development unit A front side B back side

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Claims (4)

(57) [Claims] 1. A front plate and a rear plate, which are opposed to each other on the front side and the rear side of the image forming apparatus main body with a space therebetween, and an image forming unit movably supported by these side plates, The image forming unit has a unit element movable with respect to the unit main body, and the unit main body and the unit element are arranged in a region on the back side of the unit main body and on the front side of the rear side plate. In the image forming apparatus that is operated via the respective drive elements, at least a portion of the rear side plate facing the rear side end portion of the unit main body is recessed into the rear side of the image forming apparatus main body. An image forming apparatus, wherein the image forming apparatus is formed to be a diaphragm. 2. A rear end portion of the unit main body with respect to a rear plate portion facing a rear end portion of a pair of conveying rollers for conveying a recording paper rotatably supported by the front and rear plates. The image forming apparatus according to claim 1, wherein portions of the rear side plates facing each other are formed by drawing so as to be recessed toward the inner side of the main body of the image forming apparatus. 3. The image forming unit is a developing unit that forms a toner image on the surface of an image carrier supported by a front plate and a rear plate, and is a rear unit facing a rear end portion of the image carrier. The portion of the rear plate facing the rear end of the unit main body of the developing unit is narrowed with respect to the side plate so as to be recessed toward the rear side of the image forming apparatus main body. The image forming apparatus described. 4. The image forming unit is a developing unit for forming a toner image on a surface of an image carrier supported by a front side plate and a rear side plate, and a rear unit facing a back side end portion of the image carrier. 3. The side plate portion and the rear plate portion facing the rear end of the unit main body in the developing unit are both formed so as to be recessed in the rear side of the image forming apparatus main body. The image forming apparatus according to item 1.