JP2002278316A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively maintain the positional accuracy between a sheet guiding body for guiding a sheet to a nip arranged between an image carrier and a transfer means and the image carrier, to guide the sheet to the nip without damaging the carrier and to effectively transfer an image to the sheet. SOLUTION: The sheet guiding body 8 has a 1st guiding part 81 for guiding the sheet A while coming into contact with one side of the sheet A and a 2nd guiding part 82 for guiding the sheet A guided by the 1st guiding part 81 to the nip (a) arranged between the image carrier 4 and the transfer roller 10 and a suppression body 23 for suppressing the deformation of the 1st guiding part 81 is joined to the rear face of the 1st guiding part 81.

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 provided with a transfer means for transferring an image carried on an image carrier to a sheet such as paper based on an electrophotographic process.

[0002]

2. Description of the Related Art An image forming apparatus such as a printer includes an image bearing member such as a belt-shaped photosensitive member, a drum-shaped photosensitive member, a belt-shaped intermediate transfer member, a drum-shaped intermediate transfer member, and the like. Transfer roller for transferring the transferred toner image onto the sheet, and a sheet guide for guiding the sheet conveyed toward the image carrier to a nip between the image carrier and the transfer unit. . Further, the toner image carried on the image carrier is sent along with the traveling of the image carrying surface, and a sheet is inserted into the nip at the timing when the toner image reaches a predetermined position, and transferred to the image carrier. The toner image on the image bearing surface of the image bearing member is transferred to a sheet using an electrostatic voltage between the roller and the roller.

In the above-described image forming apparatus, a charger for charging the image carrier around the image carrier and a laser for carrying an electrostatic latent image corresponding to the original image on the image carrier. An exposure device having a beam scanner, a developing device for developing an electrostatic latent image carried on the image carrier, a transfer roller for transferring a developed toner image of the image carrier to a sheet, and removing toner remaining on the image carrier A cleaning device and a static eliminator for removing the charge of the image carrier are arranged along the rotation direction of the image carrier.

In the color image forming apparatus, the toner images of the respective colors of YMCK formed on the image carriers corresponding to the respective colors of YMCK are temporarily transferred to an intermediate transfer body as an image carrier. Is configured to transfer the toner image of the intermediate transfer member onto a sheet after the toner images are superimposed on each other. In this color image forming apparatus, the transfer roller, the static eliminator, A cleaning device and the like are arranged.

Incidentally, in the image forming apparatus configured as described above, JP-A-6-3974 and JP-A-6-3974.
As disclosed in JP-A-167893, JP-A-8-110716, JP-A-10-198199, etc., a sheet conveyed toward an image carrier passes through a conveyance path near the image carrier. Must be inserted into the nip. This is because the transferred image is disturbed due to the jump of the rear end of the sheet conveyed from the registration roller, and the toner between the image carrier and the gap between the image carrier and the sheet near the nip where the electric field is strong. The toner image carried on the image carrier is prevented by preventing scattering of the image produced by flying on the sheet and occurrence of a transfer image defect due to a sheet loop caused by a difference in rotational movement speed between the image carrier and the transfer roller. This is because the toner image is transferred onto the sheet without disturbing the toner image.

[0006] As described above, the sheet guide for guiding the sheet to the nip through the conveyance path close to the image carrier needs to be disposed at a position near the image carrier. In addition, since the image carrier is a consumable, the image carrier is detachably mounted. Therefore, the sheet guide for guiding the sheet to the nip between the image carrier and the transfer roller is required to have extremely high positional accuracy. Recently, the image forming apparatus has been downsized, and along with this downsizing, an image carrier and a device for forming an image arranged around the image carrier have also been downsized. Since the miniaturization of the image carrier is superior to the miniaturization of the devices around the image carrier, the devices are densely packed around the image carrier and around the nip portion. The devices arranged around will be arranged at a small interval,
The sheet guide is also arranged by utilizing a small space between the transfer roller and the developing device. Conventionally, JP-A-6-3974, JP-A-6-167893, JP-A-8-110716, and JP-A-10-19
As disclosed in Japanese Patent Application Publication No. 8199 or the like, a sheet guide body is formed of a plate body made of resin, metal, or the like having a uniform thickness in a sheet guiding direction.

[0007]

By the way, in the sheet guide disposed at a position near the image carrier, the conveying force of the sheet conveyed by the conveying means is applied from the sheet to the sheet guide. Further, since a removing force for removing the sheet stopped at the entrance side to the nip due to a trouble of the image forming apparatus is applied to the sheet guide, the thickness of the sheet guide is made relatively thick, It is necessary to suppress the displacement due to the conveying force, suppress the deformation due to the removing force, and maintain the original positional accuracy.

However, in the prior art, a sheet guide formed of a plate made of resin, metal, or the like is used to make the thickness uniform, so that the sheet guide is disposed close to the image carrier. Was an obstacle to that. In addition, due to the thickness of the sheet guide, it has been difficult to dispose it near a nip where devices are densely packed. Further, when a bent portion or the like is provided in the sheet guide, there is a problem that the sheet guiding accuracy is reduced.

Further, when the thickness of the sheet guide is made uniform, the sheet guide is displaced by the sheet conveying force, so that stable sheet guidance cannot be performed, and the sheet guide is produced by the removing force. The body is deformed, the positional accuracy with the image carrier is reduced and the image carrier comes into contact with the image carrier, and the image carrier is damaged, or the sheet is not properly guided to the nip, and the transfer is not performed well. Will be. Therefore, it was impossible to reduce the thickness of the sheet guide uniformly.

The present invention has been made in view of such circumstances, and a main object is to use a sheet guide having a first guide and a second guide, and to provide a first guide on the back surface of the first guide. By using a small space, the sheet can be fed to the nip between the image bearing member and the transfer means by using a small space, and a stable state can be maintained by joining the suppressor that suppresses the deformation of the sheet. It is an object of the present invention to provide an image forming apparatus capable of performing the above.

Another object is to provide a moving guide for guiding the movement of the image carrier while maintaining a gap between the image carrier and the sheet guide at a position near the sheet guide. It is an object of the present invention to provide an image forming apparatus which can protect an image carrier when the image carrier is moved in a direction along the center of rotation and is detached.

Still another object is to form the sheet guide body and the suppressor or the moving guide body from a metal plate, project a protruding portion from the sheet guide body, and caulk the protruding portion to form the suppressor. Another object of the present invention is to provide an image forming apparatus having a sheet guide that can be easily processed by joining a moving guide to a back surface of the sheet guide.

Another object of the present invention is to provide a guide unit for guiding the movement of the developing device which enables the sheet guide to move in the direction in which the sheet is guided by the restraining unit or the moving guide joined to the sheet guide. An object of the present invention is to provide an image forming apparatus that can easily incorporate a developing device into a predetermined position.

[0014]

According to a first aspect of the present invention, there is provided an image forming apparatus, comprising: an image carrier on which an image is carried; transfer means for transferring an image of the image carrier onto a sheet; And a sheet guide for guiding the conveyed sheet to a nip between the image carrier and the transfer means, wherein the sheet guide is configured to guide the sheet while contacting one side of the sheet. A first guide portion; and a second guide portion for guiding the sheet guided by the first guide portion to the nip, and a suppressor for suppressing deformation of the first guide portion is joined to a back surface of the first guide portion. It is characterized by having been done.

According to the first aspect of the present invention, the suppressor joined to the back surface of the first guide portion for guiding the sheet while being in contact with one side of the sheet suppresses deformation of the first guide portion. Can be satisfactorily prevented from displacing the sheet guide body due to the sheet conveying force or deforming the sheet guide body due to the sheet removing force. Does not have the suppressor, the thickness of the second guide can be reduced uniformly, and the second guide can be very close to the image carrier. Therefore, the position accuracy of the sheet guide with respect to the image carrier can be maintained satisfactorily, and the sheet can be favorably guided to the nip without damaging the image carrier, and image transfer to the sheet can be performed. It can be performed well.

An image forming apparatus according to a second aspect of the present invention provides a rotatable image carrier for carrying an image, transfer means for transferring the image of the image carrier to a sheet, and a sheet conveyed toward the image carrier. A sheet guide for guiding the sheet to a nip between the image carrier and the transfer means, wherein the image carrier is movable in a direction along the center of rotation of the image carrier. A moving guide for guiding the movement of the image carrier while maintaining a gap with the sheet guide is provided at a position near the sheet guide.

According to the second aspect of the present invention, since the moving guide provided at a position near the sheet guide guides the movement of the image carrier, the space between the image carrier and the sheet guide is provided. The image carrier can be attached and detached without being damaged by the sheet guide even when good transfer performance is obtained so as to improve the workability of attaching and detaching the image carrier. Can be.

In the image forming apparatus according to a third aspect of the present invention, the sheet guide body guides the sheet while contacting one side of the sheet, and guides the sheet guided by the first guide to the nip. A second guide portion, wherein the movable guide body is in contact with the first guide portion to suppress deformation of the first guide portion.

According to the third aspect of the present invention, the moving guide body which is in contact with one side of the sheet and guides the sheet and which is in contact with the first guide portion suppresses deformation of the first guide portion. Since the sheet guide body can be reinforced, it is possible to prevent the sheet guide body from being displaced by the sheet conveying force and the sheet guide body from being deformed by the sheet removing force. Since the moving guide is not provided, the thickness of the second guide can be reduced uniformly, and the second guide can be very close to the image carrier. Therefore, the position accuracy of the sheet guide with respect to the image carrier can be maintained satisfactorily, and the sheet can be favorably guided to the nip without damaging the image carrier, and image transfer to the sheet can be performed. It can be performed well.

An image forming apparatus according to a fourth aspect of the present invention is characterized in that the sheet guide and the suppressor or the moving guide are metal plates.

In the fourth invention, the second plate is formed by a metal plate.
The thickness of the guide portion can be further reduced, and the thicknesses of the first guide portion, the suppressor, and the moving guide member can be further reduced, and the strength of the sheet guide member can be increased. . Therefore, the position accuracy of the sheet guide with respect to the image carrier can be maintained satisfactorily while reducing the thickness, and the sheet can be favorably guided to the nip without damaging the image carrier. The image can be transferred to the satisfactorily.

According to a fifth aspect of the present invention, there is provided the image forming apparatus according to the first aspect.
The guide portion has a convex portion projecting in a direction opposite to the surface contacting the sheet, and the suppressor or the moving guide body is joined to the back surface of the first guide portion by caulking the convex portion. It is characterized by the following.

According to the fifth aspect of the present invention, since the protrusion projecting in the direction opposite to the surface in contact with the sheet joins the suppressor or the moving guide to the back surface of the first guide, the joining means is provided. The sheet can be guided favorably without being affected by, and the joining operation for joining the first guide portion and the suppressing body or the moving guide body can be easily performed.

According to a sixth aspect of the present invention, in the image forming apparatus, the first
The guide portion has a convex piece protruding in a direction opposite to a surface in contact with the sheet.

According to the sixth aspect of the present invention, the first guide portion can be reinforced by the projecting piece protruding in the direction opposite to the surface in contact with the sheet. Body deformation can be prevented well.

An image forming apparatus according to a seventh aspect is characterized in that the suppressor or the moving guide has a convex piece facing the convex piece. According to the seventh aspect, since the warp direction of the sheet guide body is equal to the warp direction of the suppressing body or the moving guide body, it is easy to process a projection or the like for joining.

An image forming apparatus according to an eighth aspect of the present invention has a developing device for developing an image carried on the image carrier and enabling the sheet guide to move in a direction for guiding a sheet. And a third guide portion for guiding the movement of the developing device.

In the eighth aspect, when the developing device is moved in a direction in which the sheet guide guides the sheet and the developing device is mounted, the developing device may be moved while being guided by the third guide portion. Therefore, even if the position of the developing device is shifted, the developing device can be smoothly mounted at a predetermined position without being caught by the moving guide.

An image forming apparatus according to a ninth aspect of the present invention has a support on which the image carrier is supported, one of the support and the developing device has a positioning concave portion, and the other has the third guide portion. And a positioning projection that engages with the positioning recess to determine the position of the developing device when the developing device is moved along.

According to the ninth aspect, when the developing device is moved in the direction in which the sheet guide guides the sheet and the developing device is mounted, the developing device can be reliably guided to a predetermined position.

[0031]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings showing the embodiments. FIG. 1 is a vertical sectional front view of an image forming apparatus according to the present invention.

This image forming apparatus, as shown in FIG.
A scanner unit 1 for reading an image of a document placed on the platen 11; and a scanner unit 1 disposed below the scanner unit 1 and corresponding to the document image read by the scanner unit 1. Apparatus main body 2 having image carrier 4 carrying a toner image and frame 5 supporting image carrier 4
And a sheet supply unit 3 arranged below the apparatus main body 2 to supply a sheet A to the image carrier 4.

An automatic document feeder 12 for transporting a document to be read to the document table 11 is provided on an upper portion of the document table 11 of the scanner unit 1 so as to be openable and closable.

The scanner unit 1 includes a document scanning body 13 which reciprocates in parallel along the lower surface of the document table 11, an optical lens 14, and a CCD line sensor 15 serving as a photoelectric conversion element.
Are provided.

The original scanning body 13 has a first scanning section 13a and a second scanning section 13b, and the first scanning section 13a
Has an exposure lamp for exposing the surface of the document image, and a first mirror for deflecting the reflected light image from the document in a predetermined direction, while maintaining a constant distance from the lower surface of the document table 11. It reciprocates in parallel at a predetermined scanning speed.

The second scanning section 13b is connected to the first scanning section 13a
A second mirror and a third mirror for further deflecting the reflected light image from the document deflected by the first mirror in a predetermined direction.
It has a mirror and reciprocates in parallel with the first scanning unit 13a while maintaining a constant speed relationship.

The optical lens 14 reduces the reflected light image from the document deflected by the third mirror 13f of the second scanning section 13b, forms an image at a predetermined position on the CCD line sensor 15, and reads the read image. Is the CCD line sensor 15
Is converted into an electric signal and sent to the apparatus main body 2.

The sheet supply section 3 has a sheet cassette 31 in which sheets A are stacked and stored, and a supply roller 32 for separating and supplying the sheets in the sheet cassette 31 one by one. Sheet A supplied
The image carrier 4 extends along a transport path B on which transport rollers 6 and 6, registration rollers 7 and 7 and a sheet guide 8 are disposed.
Transported to

The image carrier 4 uses a photosensitive drum 4a rotatably supported by a support 4b, and is movably mounted on the frame 5 by the support 4b. Around the image carrier 4, a charger for charging the image carrier 4 as a process unit of an electrophotographic process, and an exposure device having a laser beam scanner for carrying an electrostatic latent image corresponding to a document image on the image carrier 4 A developing unit 9 for developing the electrostatic latent image carried on the image carrier 4, a transfer roller 10 as a transfer unit for transferring the developed toner image of the image carrier 4 onto a sheet, and remains on the image carrier 4. A cleaning device for removing the toner is arranged along the rotation direction of the image carrier 4.

As a result, the image bearing surface of the image bearing member 4 is charged to a predetermined potential by the charger, and the charged image bearing member 4 is irradiated with a light beam corresponding to the original image by the exposure device. An electrostatic latent image is formed on the image bearing surface of the image carrier 4. Next, a developer such as toner is applied to the electrostatic latent image by a developing device 9 to form a toner image.

This toner image is transferred to the sheet A conveyed from the registration rollers 7, 7 by the transfer roller 10. Sheet A to which this toner image has been transferred
Is separated from the image bearing surface of the image carrier 4, sent along the sheet conveying path B, and sent to the developing device 9 provided in the conveying path B downstream in the conveying direction, and the developing device 9 After the toner image transferred to the main body is fixed,
The sheet is discharged onto a tray of a sheet discharge section 21 provided at the upper part of the sheet. Further, the image carrier 4 to which the toner image has been transferred
The residual toner remaining on the image bearing surface is collected by the cleaning device.

FIG. 2 is a front view of the image carrier. The image carrier 4 can be moved in a direction along the center of rotation along a rail-shaped support portion 22 provided on the frame 5, and can be attached to and detached from the frame 5 by this movement. The developing device 9 includes a developing roller 9a which is in contact with the image bearing surface of the image carrier 4 and is rotatably held by a holder 9b. The sheet guide 8 is held by the holder 9b. Can be moved in a direction in which the frame 5 is guided.
Can be attached to and detached from.

When the developing device 9 is mounted at a predetermined position, the developing device 9 is separated from the image bearing surface of the image carrier 4 and inserted into a predetermined position in the frame 5 in a longitudinal direction thereof, and then not shown. The image forming apparatus is configured to be mounted by being raised to a predetermined position corresponding to the image carrying surface via a developing device supporting mechanism that is pushed up in the direction of the image carrier 4 by operating the mounting lever.

FIG. 3 is an enlarged front view of the transfer means, FIG. 4 is a front view of the sheet guide, FIG. 5 is a perspective view of the sheet guide, and FIG. 6 is a perspective view of the sheet guide and the suppressor. 7
8 is a cross-sectional view taken along the line VII-VII of FIG. 6, FIG. 8 is a perspective view showing a state where the sheet guide is assembled, FIG. 9 shows a portion where the image carrier is supported, and FIG. FIG. 10B is a side view showing a state in which the image carrier is mounted, and FIG. 10 is a front view showing a process in which the developing device is mounted.

The sheet guide 8 guides the sheet A conveyed from the sheet supply unit 3 through the registration rollers 7 to the nip a between the image carrier 4 and the transfer roller 10. A first flat guide portion 81 having a rectangular plate shape that guides the sheet A while being in contact with one side of A, and a flat first flat guide portion 81 that guides the sheet A guided by the first guide portion 81 to the nip a. 2 guide 82 and the first guide 8
1 and a plurality of projections 83 projecting from the sheet entry side end in a direction opposite to a surface contacting the sheet A, and a plurality of projections projecting from a back surface of the first guide portion 81 opposite to the surface contacting the sheet A. And is integrally formed of a metal plate.

The first guide portion 81 is connected to the registration rollers 7,
7 is arranged so that the angle between the nip b and the tangent α at the nip b is an acute angle, and the second guide portion 82 is an angle for allowing one side of the sheet A to enter the nip a at a predetermined angle. It is bent at. The approach angle in this case is set so that one side of the sheet A is directed in a direction approximate to the tangent β direction of the nip a.

By setting the angle of entry, the image carrier 4
The sheet A can be made to enter the nip a with the toner image feeding direction and the sheet A conveying direction being as same as possible without contacting the toner image carried on the sheet A.

A suppressor 23 for suppressing deformation of the first guide portion 81 is integrally joined to the back surface of the first guide portion 81 of the sheet guide body 8 configured as described above. A sheet guide 8 is detachably attached to a holding member 24 holding the registration rollers 7, 7 via the sheet guiding member 8.

The suppressor 23 is formed of a rectangular plate-like metal plate having a plurality of fitting holes 23a corresponding to the convex portions 84. The convex portions 84 are formed in the fitting holes 23a of the suppressor 23. Are fitted to each other and the tip of the convex portion 84 is crimped to join the suppressor 23 to the back surface of the first guide portion 81. A long hole-shaped fitting hole 23b is formed at one end in the longitudinal direction of the suppressor 23, and a plurality of screw insertion holes 23c are formed at the other end at a distance in the longitudinal direction. .

Further, the holder 24 to which the suppressor 23 is attached has a first end into which both ends of the suppressor 23 are inserted.
A concave portion 24a, a second concave portion 24b, a positioning convex portion 24c protruding from the first concave portion 24a, and a screw hole formed in the second concave portion 24b are provided. While being inserted into the concave portion 24a and the second concave portion 24b,
By fitting the fitting hole 23b into the positioning protrusion 24c and tightening the screw 25 from the screw insertion hole 23c to the screw hole, the sheet guide body 8 is held via the restraining body 23 by the holding body 24 of the registration rollers 7,7. It is attached to.

A third guide portion 26 which is inclined at a side opposite to the second guide portion 82 at the end of the suppressor 23 on the side of the second guide portion 82 and guides the movement of the developing device 9 in the mounting direction. The third
A flat moving guide 27 that extends from the tip of the guide 26 toward the second guide 82 and guides the movement of the image carrier 4 is integrally formed. A convex piece 23d facing the convex piece 83 is integrally formed at the end opposite to the third guide portion 26.

The moving guide 27 has positioning recesses 27a at both ends in the longitudinal direction, and the image carrier 4 in which the image bearing drum 4a is supported by the support 4b is mounted in the frame 5. At this time, one of both ends of the support 4b engages with the movement guide 27, and guides the movement of the image carrier 4 in this engaged state. With this guidance, the image carrier 4
When is moved to the mounting completed position, both ends of the support 4b engage with the positioning recesses 27a, 27a to restrict the movement of the image carrier 4. At this time, the support 4b is connected to the rail-shaped support portion 22 of the frame 5.
Supported by

The tip of the moving guide 27 and the second guide 8
2, a space is provided between the convex piece 23d and the moving guide body 27. When the suppressor 23 is processed by this space, the height h between the convex piece 23d and the moving guide body 27 is defined. Even if an error occurs in the dimension, the influence can be eliminated, and the angle of the second guide portion 82 with respect to the first guide portion 81 because the moving guide body 27 does not contact the back surface of the second guide portion 82. There is no problem such as changing the number.

The moving guide 27 is provided with the first guide portion 8.
The front end of the second guide 82 (image carrier 4 side) is located closer to the bent portion 8a between the first and second guides 82.
Accordingly, the moving guide 27 does not come into contact with the vicinity of the image carrier 4 without requiring a severe precision in the height dimension h of the suppressor 23, so that the arrangement accuracy of the sheet guide 8 is improved. Thus, stable sheet conveyance can be performed.

When the developing device 9 supporting the developing roller 9a is mounted in the frame 5, the third guide portion 26 can contact one side 9d of the holding member 9b.
By this contact, the position of the developing device 9 is corrected, and the developing device 9 can be smoothly moved to the mounting completion position along the third guide portion 26.

The holding member 9b has an abutment surface 9e for abutting on the support 4b, and a positioning projection 91 is projected from the contact surface 9e. When the developing device 9 held by the holding member 9b moves to the mounting completion position along the third guide portion 26, the positioning protrusion 91 moves to the positioning recess 41. To limit the movement of the developing device 9 via the holding member 9b. 3 and 5, reference numeral 28 denotes an auxiliary plate disposed between the sheet guide 8 and the transfer roller 10, and the second guide portion 82 of the sheet guide 8 contacts the transfer roller 10. To ensure that they do

In the image forming apparatus configured as described above, the sheet guide 8 is assembled in the frame 5 via the holding member 24 holding the registration rollers 7,7. The suppressor 23 is joined to the first guide portion 81 of the sheet guide 8, and the suppressor 23 is connected to the first guide portion 81.
Since the first guide portion 81 is reinforced by suppressing the deformation of
The displacement of the sheet guide body 8 due to the conveying force of the sheet A and the deformation of the sheet guide body 8 due to the removing force of the sheet A can be favorably prevented.
The thickness of the guide portion 82 can be reduced uniformly, and the second
The guide 82 can be brought very close to the image carrier 4 and the arrangement accuracy of the sheet guide 8 can be improved. Further, since the length of the second guide portion 82 in the sheet guiding direction is not so required, the leading end of the sheet guide body 8 in the sheet conveyance direction is simply compared to the case where the sheet guide body 8 is simply bent in the middle of the sheet guiding direction. The position accuracy of the portion can be increased and the strength can be increased, and the second guide portion 82 can be satisfactorily prevented from contacting the image carrier 4 due to the conveying force of the sheet A and the removing force of the sheet A. . Therefore, the sheet A can be satisfactorily guided to the nip a without damaging the image carrier 4, and the image transfer to the sheet A can be satisfactorily performed.

The suppressor 2 joined to the sheet guide 8
3 is integrally provided with a movement guide 27 for guiding the movement of the image carrier 4, so that when the image carrier 4 is mounted,
The image carrier 4 can be smoothly mounted at a predetermined mounting completion position without making contact with the sheet guide body 8 and the suppressor 23, so that the workability of assembling the image carrier 4 can be improved and the image carrier can be improved. 4 can be satisfactorily prevented from being damaged by the sheet guide 8 and the suppressor 23.

Further, since the suppressor 23 is provided with the third guide portion 26 for guiding the movement of the developing device 9, when the developing device 9 is mounted, it is moved even if the position of the developing device 9 is shifted. The developing device 9 can be smoothly mounted to a predetermined mounting completed position without being caught by the guide body 27.

Also, a convex piece 83 provided on the first guide portion 81
Accordingly, the sheet guide body 8 can be prevented from warping in the longitudinal direction and can be stably formed. Therefore, the sheet guide body 8 can maintain sufficient strength even if the thickness thereof is reduced. The sheet guide 8 can be arranged near the nip a, and can be arranged in a slight space between the transfer roller 10 and the developing device 9.

Further, a fitting hole 23b drilled at one longitudinal end of the suppressor 23 joined to the sheet guide 8 is fitted into the positioning convex portion 24c of the holder 24, and a screw insertion hole at the other end. Since the sheet guide 8 can be assembled by tightening the male screw 25 inserted into the screw 23c into the screw hole of the holder 24, the workability of assembling the sheet guide 8 can be improved.

In the embodiment described above, the movement guide 27 and the third guide 26 are provided on the suppressor 23.
In addition, the movement guide 27 and the third guide 26 may be omitted, or the suppressor 23 having the third guide 26 may be joined to the first guide 81 to form the movement guide 27 separately. The moving guide 27 may be provided at a position near the sheet guide 8. In addition, the third guide portion 26 may be provided on a moving guide 27 formed separately from the sheet guide 8. Further, the moving guide body 27 formed separately from the sheet guide body 8 is provided with a joint portion joined to the back surface of the first guide portion 81, and the joint portion is integrally formed by the above-described joining means such as caulking. May be joined.

Although the sheet guide 8 and the suppressor 23 in the above-described embodiment are formed of a metal plate, they may be formed of a synthetic resin plate.

[0064]

As described in detail above, according to the first and third aspects of the present invention, the suppressing body or the moving guide body can suppress the deformation of the first guide portion and reinforce the first guide portion. The thickness of the second guide portion can be reduced uniformly, and the second guide portion can be brought very close to the image carrier, and the positional accuracy of the sheet guide with respect to the image carrier can be improved. Thus, the sheet can be satisfactorily guided to the nip without damaging the image carrier, and the image can be transferred to the sheet satisfactorily.

According to the second aspect of the present invention, since the moving guide provided at a position near the sheet guide guides the movement of the image carrier, the distance between the image carrier and the sheet guide is reduced. Even when the transfer performance is small and good transfer performance is obtained, the image carrier can be attached and detached without being damaged by the sheet guide, and the workability of attaching and detaching the image carrier can be improved. it can.

According to the fourth aspect of the present invention, it is possible to maintain the position accuracy of the sheet guide with respect to the image carrier while reducing the thickness thereof, and to favorably transfer the sheet to the nip without damaging the image carrier. The image transfer to the sheet can be favorably performed.

According to the fifth aspect of the present invention, the sheet can be satisfactorily guided without being affected by the means for joining the suppressing body or the moving guide body to the back surface of the first guide portion, and the first guide can be provided. The joining operation for joining the portion and the suppressing body or the moving guide body can be easily performed.

According to the sixth aspect, the first guide portion can be reinforced by the convex piece protruding in the direction opposite to the surface in contact with the sheet. Can be satisfactorily prevented from being deformed.

According to the seventh aspect, the warping direction of the sheet guide body is equal to the warping direction of the suppressing body or the moving guide body, so that the processing of the projections and the like for joining becomes easy.

According to the eighth aspect, when the developing device is moved in the direction in which the sheet guide guides the sheet and the developing device is mounted, the developing device can be moved while being guided by the third guide portion. Therefore, even if the position of the developing device is shifted, the developing device can be smoothly mounted at a predetermined position without being caught by the moving guide.

According to the ninth aspect, when the developing device is moved in the direction in which the sheet guide guides the sheet and the developing device is mounted, the developing device can be reliably guided to a predetermined position.

[Brief description of the drawings]

FIG. 1 is a vertical sectional front view of an image forming apparatus according to the present invention.

FIG. 2 is a front view of an image carrier of the image forming apparatus according to the present invention.

FIG. 3 is an enlarged front view of a transfer unit of the image forming apparatus according to the present invention.

FIG. 4 is a front view of a sheet guide portion of the image forming apparatus according to the present invention.

FIG. 5 is a perspective view of a sheet guide portion of the image forming apparatus according to the present invention.

FIG. 6 is a perspective view of a sheet guide and a suppressor of the image forming apparatus according to the present invention.

FIG. 7 is a sectional view taken along line VII-VII of FIG. 6;

FIG. 8 is a perspective view of the image forming apparatus according to the present invention in a state where a sheet guide is assembled.

9A and 9B show a portion where the image carrier of the image forming apparatus according to the present invention is supported, wherein FIG. 9A is a side view of a process of attaching the image carrier, and FIG. It is a rear side view.

FIG. 10 is a front view showing a process in which a developing device of the image forming apparatus according to the present invention is mounted.

[Explanation of symbols]

 Reference Signs List 4 image carrier 4b support 41 positioning recess 8 sheet guide 81 first guide 82 second guide 83 convex piece 84 convex 9 developing unit 91 positioning convex 10 transfer roller (transfer unit) 23 inhibitor 26 third Guide part 27 Moving guide body a Nip

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Tatsuya Inoue 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka F-term (reference) 2H071 BA03 BA04 BA13 BA16 BA19 DA08 DA09 DA15 DA23 EA04 EA06 2H200 GA23 GA34 HA02 HA12 HB03 HB12 HB22 JA02 JB12 JB17 JB20 JB39 JB43 JB45 LA12 LA22 MA01 MA02 3F101 FB04 FC18 FD01 LA02 LA07 LB03

Claims (9)

[Claims] An image bearing member on which an image is carried; transfer means for transferring an image of the image carrier onto a sheet; and a sheet conveyed toward the image carrier, wherein the sheet is transported to the image carrier and the transfer means. An image forming apparatus including a sheet guide for guiding to a nip between the first guide and a sheet guided by the first guide while the sheet guide is in contact with one side of the sheet; And a second guide section for guiding the first guide section to the nip, and a suppressor for suppressing deformation of the first guide section is joined to a back surface of the first guide section. 2. A rotatable image carrier on which an image is carried, transfer means for transferring an image of the image carrier onto a sheet,
A sheet guide for guiding a sheet conveyed toward the image carrier to a nip between the image carrier and a transfer unit, wherein the image carrier is movable in a direction along a rotation center thereof. In the forming apparatus, a moving guide that guides the movement of the image carrier while maintaining a gap between the image carrier and the sheet guide is provided at a position near the sheet guide. Image forming apparatus. 3. The sheet guide body has a first guide portion for guiding the sheet while being in contact with one side of the sheet, and a second guide portion for guiding the sheet guided by the first guide portion to the nip. The image forming apparatus according to claim 2, wherein the moving guide body is in contact with the first guide unit to suppress deformation of the first guide unit. 4. The image forming apparatus according to claim 1, wherein the sheet guide and the suppressor or the moving guide are metal plates. 5. The first guide portion has a convex portion projecting in a direction opposite to a surface in contact with the sheet, and caulking the convex portion to guide the suppressor or the moving guide member to the first guide. The image forming apparatus according to claim 4, wherein the image forming apparatus is joined to a back surface of the unit. 6. The image forming apparatus according to claim 4, wherein the first guide portion has a projection protruding in a direction opposite to a surface contacting the sheet. 7. The image forming apparatus according to claim 6, wherein said suppressing body or said moving guide has a convex piece facing said convex piece. 8. A developing device for developing an image carried on the image carrier and enabling the sheet guide to move in a direction for guiding a sheet, wherein the developer or the movement guide is provided. 4. The image forming apparatus according to claim 1, wherein the body is provided with a third guide for guiding the movement of the developing device. 9. A developing device comprising: a support on which the image carrier is supported; one of the support and the developing device having a positioning concave portion; and the other moving the developing device along the third guide portion. The image forming apparatus according to claim 8, further comprising a positioning projection that engages with the positioning recess to determine the position of the developing device.