JPH09106125A - Electrophotographic image forming device and process cartridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To keep excellent transfer performance by the appropriate action of a pretransfer guide plate and to improve jamming processability for the occasion that jamming occurs while transfer material is passing the guide plate even in the case of using a cartridge system having the limitation of aligning accuracy with a body. SOLUTION: The pretransfer guide plate is constituted of an upper guide plate 21 provided on a cartridge side and a lower guide plate 22 provided on a body side, and a projection 23 is formed at the lower part of the upper guide plate 21 and a groove 22' is formed on the lower guide plate 22, respectively. Furthermore, the lower guide plate 22 is set to move back and forth and up and down, and the upper guide plate 21 acts to move the lower guide plate 22 to an optimum position and an optimum angle while securing a gap required to carry the transfer material by meshing the projection 23 of the upper guide plate 21 with the groove 22' of the lower guide plate 22 at the time of the cartridge loading.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming apparatus such as a printer and a facsimile, and a process cartridge detachable from the electrophotographic image forming apparatus.
In particular, it relates to pre-transfer guide means provided for the transfer means.

[0002]

SUMMARY OF THE INVENTION The present invention is a further development of the prior art described below, and an object thereof is to obtain an electrophotographic image forming apparatus and a process cartridge in which a recording medium jammed with paper can be easily removed. And

Another object of the present invention is to obtain an electrophotographic image forming apparatus and a process cartridge which can obtain good transferability and can accurately obtain the positioning of the guide means of the recording medium before transfer with respect to the transfer portion.

A further object of the present invention is to provide an electrophotographic image forming apparatus and a process cartridge, which have a shutter member for protecting an electrophotographic photosensitive member and have a structure in accordance with each of the above objects, and which have a simplified device. .

[0005]

Means for Solving the Problems A first invention of the present invention is:
A process cartridge that has an electrophotographic photosensitive member and a process unit that acts on the electrophotographic photosensitive member and is detachable from the main body of the image forming apparatus, and a transfer that transfers the image formed on the electrophotographic photosensitive member onto a recording medium. In the electrophotographic image forming apparatus, a means for guiding the recording medium to the electrophotographic photosensitive member and the transfer means, the guide means for the recording medium before transfer,
An electrophotographic image forming apparatus having an upper guide plate provided in a process cartridge and a lower guide plate provided in a main body of the image forming apparatus.

According to a second aspect of the present invention, the lower guide plate is provided so as to be movable in the vertical direction and in the front-rear direction which is substantially the same direction as the recording medium conveyance direction, and the upper guide plate forms the process cartridge on the image forming unit. Positioning means that engages with the lower guide plate when mounted on the apparatus main body, secures a gap required to convey the recording medium between the upper and lower guide plates, and moves the upper and lower guide plates to a desired position and angle. The electrophotographic image forming apparatus according to the first invention, characterized in that

According to a third aspect of the present invention, the guide means for the recording medium before transfer is an upper guide plate having a downward projection on at least one of the left and right ends thereof, and is vertically and recorded on the image forming apparatus main body side. The process cartridge comprises a lower guide plate movably provided in the front-rear direction which is substantially the same as the medium transport direction, and has a groove that engages with a protrusion provided on the upper guide plate on at least one of the left and right ends. When mounted on the main body of the image forming apparatus, the protrusion provided on the upper guide plate meshes with the groove provided on the lower guide plate, and secures a gap required to convey the recording medium between the upper and lower guide plates. Also, the electrophotographic image according to the second invention is characterized in that the lower guide plate is set to move to a desired position and angle according to the movement of the upper guide plate. It is formed apparatus.

According to a fourth aspect of the present invention, there is provided mounting means for mounting the process cartridge in a diagonally downward direction, and the projection provided on the upper guide plate is adapted to mount the process cartridge in a diagonally downward and forward direction. Accordingly, the electrophotographic image forming apparatus according to the third invention is characterized in that the lower guide plate is pushed downward and pulled out forward.

According to a fifth aspect of the present invention, the upper guide plate also serves as a shutter that covers the surface of the electrophotographic photosensitive member when the process cartridge is not mounted and can open the surface of the electrophotographic photosensitive member when the process cartridge is mounted. The projections of the upper guide plate move the upper guide plate relative to the electrophotographic photosensitive member in a direction to open the surface of the electrophotographic photosensitive member while acting on the lower guide plate. An electrophotographic image forming apparatus according to a third aspect of the invention.

According to a sixth aspect of the present invention, the lower guide plate has a sheet feeding side end fixed to a rotatable rotary shaft and a transfer side end pushed upward by a pressing means about the rotary shaft. A storage plate having a portion is movably fitted in a front-rear direction which is substantially the same direction as the recording medium conveyance direction, and is urged forward by an elastic member that can expand and contract.
The electrophotographic image forming apparatus according to any one of items 1 to 5.

In a seventh aspect of the present invention, the pressurizing means for pushing up the transfer side end of the lower guide plate from the lower side to the upper side is composed of an elastic member capable of expanding and contracting according to the strength of the recording medium. Any one of the second to sixth inventions characterized in that
The electrophotographic image forming apparatus according to item No. 3.

In an eighth aspect of the present invention, the electrophotographic photosensitive member has a cylindrical shape, and the set position of the upper guide plate is positioned with reference to the central axis of the cylinder of the cylindrical electrophotographic photosensitive member. The electrophotographic image forming apparatus according to any one of the second to seventh aspects of the invention.

A ninth aspect of the present invention is to transfer the image formed on the electrophotographic photosensitive member onto a recording medium, and to guide the recording medium to the electrophotographic photosensitive member and the transfer means. In the process cartridge which is detachable from the electrophotographic image forming apparatus having the guide means for the recording medium before transfer, and which has the electrophotographic photosensitive member and the process means acting on the electrophotographic photosensitive member, the recording before the transfer is performed. The medium guiding means is composed of an upper guide plate and a lower guide plate, and the upper guide plate is provided in the process cartridge.

A tenth aspect of the present invention is to transfer the image formed on the electrophotographic photosensitive member onto a recording medium, and to guide the recording medium to the electrophotographic photosensitive member and the transfer means. In the process cartridge which is detachable from the electrophotographic image forming apparatus having the guide means for the recording medium before transfer, and which has the electrophotographic photosensitive member and the process means acting on the electrophotographic photosensitive member, the recording before the transfer is performed. The medium guide means is composed of an upper guide plate fixed to the process cartridge, and a lower guide plate provided on the main body of the image forming apparatus so as to be movable up and down and in the front-rear direction which is substantially the same as the conveyance direction of the recording medium. The upper guide plate engages with the lower guide plate when the process cartridge is mounted in the main body of the image forming apparatus to convey the recording medium between the upper and lower guide plates. A positioning means for moving to a desired position and angle of the lower guide plate while ensuring the clearance required for a process cartridge which comprises said electrophotographic photosensitive member.

In an eleventh aspect of the present invention, the upper guide plate covers the electrophotographic photosensitive member when the process cartridge is not mounted on the image forming apparatus main body, and engages with the lower guide plate when the process cartridge is mounted on the image forming apparatus main body. The process cartridge according to the ninth or tenth invention is characterized in that the electrophotographic photosensitive member is opened.

In a twelfth aspect of the present invention, the process cartridge comprises a charging means, a developing means or a cleaning means and an electrophotographic photosensitive member which are integrally formed into a cartridge, and the cartridge is attached to or detached from the main body of the image forming apparatus. A process cartridge according to the ninth, tenth, or eleventh invention that enables the process cartridge.

In a thirteenth aspect of the present invention, the process cartridge is a cartridge in which at least one of a charging unit, a developing unit and a cleaning unit and an electrophotographic photosensitive member are integrally formed into a cartridge, and the process cartridge is attached to and detached from the main body of the image forming apparatus. A process cartridge according to the ninth, tenth, or eleventh invention that enables the process cartridge.

In a fourteenth aspect of the present invention, the process cartridge is a ninth, tenth or tenth aspect in which at least a developing means and an electrophotographic photosensitive member are integrally made into a cartridge so as to be attachable to and detachable from an image forming apparatus main body. 11 is the process cartridge according to the invention.

[0019]

2. Description of the Related Art Conventionally, in an image forming apparatus using an electrophotographic image forming process, an electrophotographic photosensitive member and process means acting on the electrophotographic photosensitive member are integrally formed into a cartridge, and this cartridge is used as an image forming apparatus. A process cartridge system detachable from the main body is employed. According to this process cartridge system, the maintenance of the apparatus can be performed by the user himself without resorting to service personnel, so that the operability can be markedly improved. Therefore, this process cartridge system is widely used in image forming apparatuses.

In such an electrophotographic image forming apparatus, a transfer means is provided so as to face the electrophotographic photosensitive member provided in the process cartridge, and a guide means for the recording medium before transfer is provided on the transfer medium inlet side of the transfer means. Is provided.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION A first embodiment of the present invention is a process which has an electrophotographic photosensitive drum and process means acting on the electrophotographic photosensitive drum, and which is attachable to and detachable from an image forming apparatus main body. A cartridge, a transfer roller for transferring an image formed on the electrophotographic photosensitive drum onto a recording sheet, and a recording sheet before transfer for guiding the recording sheet to the electrophotographic photosensitive drum and the transfer roller. In the electrophotographic image forming apparatus having guide means, the guide means for the recording paper before transfer has an upper guide plate fixed to the process cartridge and a lower guide plate provided in the image forming apparatus main body. This is an electrophotographic image forming apparatus. According to the second embodiment of the present invention, the lower guide plate is provided so as to be movable in the up-down direction and in the front-rear direction which is substantially the same direction as the recording paper conveyance direction, and the upper guide plate moves the process cartridge into the image. Positioning that engages with the lower guide plate when mounted on the main body of the forming apparatus and secures a gap required to convey the recording paper between the upper and lower guide plates and moves the lower guide plate to a desired position and angle. The electrophotographic image forming apparatus according to the first embodiment of the present invention is characterized by including a means.

In a third embodiment of the present invention, the guide means for the recording paper before transfer is an upper guide plate having a downward projection on at least one of the left and right ends, and the main body of the image forming apparatus. And a lower guide plate having a groove that meshes with a protrusion provided on the upper guide plate on at least one of the left and right ends of the upper and lower guide plates. When the process cartridge is mounted on the main body of the image forming apparatus, the protrusion provided on the upper guide plate meshes with the groove provided on the lower guide plate, and is necessary to convey the recording paper between the upper and lower guide plates. The second embodiment of the invention is characterized in that a gap is secured and the lower guide plate is moved to a desired position and angle according to the movement of the upper guide plate. An electrophotographic image forming apparatus mounting.
An embodiment of a fourth invention of the present invention has a mounting means for mounting the process cartridge in a diagonally downward direction, and a protrusion provided on the upper guide plate is an operation for mounting the process cartridge in a diagonally lower front direction. Accordingly, the electrophotographic image forming apparatus according to the third embodiment of the present invention is characterized in that the lower guide plate is pushed downward and pulled out forward. In the fifth embodiment of the present invention, the upper guide plate can cover the surface of the electrophotographic photosensitive drum when the process cartridge is not mounted and can open the surface of the electrophotographic photosensitive drum when the process cartridge is mounted. It is configured as a quadruple chain link so that it doubles as a shutter, and the projections of the upper guide plate act on the lower guide plate to move the upper guide plate to the surface of the electrophotographic photosensitive drum with respect to the electrophotographic photosensitive member. The electrophotographic image forming apparatus according to the third embodiment of the present invention is characterized in that it is moved in the opening direction.

In the sixth embodiment of the present invention, the lower guide plate is pushed upward by a pressure spring about the sheet feeding side end fixed to a rotatable rotary shaft and the rotary shaft. A second to fifth feature is that a storage plate having a transfer side end is movably fitted in a front-rear direction which is substantially the same as the recording paper conveyance direction, and is biased forward by a spring member. The electrophotographic image forming apparatus according to any one of the embodiments of the invention.

In a seventh embodiment of the present invention, the pressing means for pushing up the transfer side end of the lower guide plate from the lower side to the upper side is a spring member capable of expanding and contracting according to the strength of the recording paper. The electrophotographic image forming apparatus according to any one of the second to sixth embodiments of the present invention.

In an eighth embodiment of the present invention, the electrophotographic photosensitive drum has a cylindrical shape, and the setting position of the upper guide plate is the central axis of the cylinder of the cylindrical electrophotographic photosensitive drum. The electrophotographic image forming apparatus according to any one of the second to seventh embodiments of the present invention is characterized in that the electrophotographic image forming apparatus is positioned with reference to.

According to a ninth embodiment of the present invention, a transfer roller for transferring an image formed on an electrophotographic photosensitive drum onto a recording paper, the electrophotographic photosensitive drum and the transfer roller are subjected to the recording. A process cartridge detachably mountable to an electrophotographic image forming apparatus having guide means for recording paper before transfer for guiding paper and having the electrophotographic photosensitive drum and process means acting on the electrophotographic photosensitive drum. In the process cartridge, the guide unit for the recording paper before transfer is composed of an upper guide plate and a lower guide plate, and the upper guide plate is provided in the process cartridge.

According to a tenth embodiment of the present invention, a transfer roller for transferring an image formed on an electrophotographic photosensitive drum onto a recording sheet, the electrophotographic photosensitive drum and the transfer means perform the recording. Pre-transfer recording paper guide means for guiding the paper can be attached to and detached from the electrophotographic image forming apparatus,
In a process cartridge having the electrophotographic photosensitive drum and process means acting on the electrophotographic photosensitive drum, the guide means for the recording paper before transfer is an upper guide plate fixed to the process cartridge, and an image forming unit. The apparatus main body is composed of a lower guide plate that is movable up and down and in the front-rear direction that is substantially the same direction as the recording paper conveyance direction, and the upper guide plate mounts the process cartridge on the image forming apparatus main body. At this time, it has a positioning means for engaging with the lower guide plate to secure a gap required to convey the recording paper between the upper and lower guide plates and moving the lower guide plate to a desired position and angle. A process cartridge having an electrophotographic photosensitive drum.

In an eleventh embodiment of the present invention, the upper guide plate covers the electrophotographic photosensitive drum when the process cartridge is not attached to the image forming apparatus main body, and the lower guide is attached when the process cartridge is attached to the image forming apparatus main body. The process cartridge according to the ninth or tenth embodiment of the invention is characterized in that the electrophotographic photosensitive drum is opened by engaging with a plate.

In the twelfth embodiment of the present invention, the process cartridge is an integrally formed cartridge including a charging device, a developing device or a cleaning device and an electrophotographic photosensitive drum, and the cartridge is an image forming apparatus. It is the process cartridge according to the ninth, tenth, or eleventh embodiment of the invention, which is detachable from the main body.

In the thirteenth embodiment of the present invention, the process cartridge is an image forming apparatus in which at least one of a charging device, a developing device and a cleaning device and an electrophotographic photosensitive drum are integrally formed into a cartridge. It is the process cartridge according to the ninth, tenth, or eleventh embodiment of the invention, which is detachable from the main body.

In a fourteenth embodiment of the present invention, the process cartridge is such that at least a developing device and an electrophotographic photosensitive drum are integrally formed into a cartridge so as to be attachable to and detachable from an image forming apparatus main body. Alternatively, it is the process cartridge according to the embodiment of the tenth or eleventh invention.

[Detailed Description of Embodiments] Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

(Embodiment A) FIG. 3 is a vertical sectional view showing the image forming function of the electrophotographic image forming apparatus.

In the image forming process in the configuration of FIG. 3, first, the laser light oscillated from the laser diode 1 is applied to the polygon mirror 2 and is reflected, and then the lens 3 is reflected.
The light is reflected by the folding mirror 4 and is incident on the surface of the photosensitive drum 6 rotating in the direction of the arrow in the figure. At this time, the surface of the photosensitive drum 6 is previously charged to a desired potential by the charging roller 5, and only the surface potential of the portion exposed by the laser beam is lowered to form a latent image. Next, when the toner 9 packed in the toner container 8 is conveyed to the opposite surface of the photosensitive drum 6 by the developing sleeve 7, the toner 9 charged to the same polarity as the photosensitive drum 6 in the toner container 8 is charged. By the electric field applied between the developing sleeve 7 and the core metal 6a of the photosensitive drum 6, the latent image is carried and attached to the low potential region of the latent image portion on the photosensitive drum 6, and the latent image becomes a toner image. Next, this toner image is peeled off from the surface of the photosensitive drum 6 by the high-voltage electric field applied to the transfer roller 10 and transferred onto the surface of the recording material 13 of the transfer material. The recording paper 13 on which the toner image is placed is then conveyed to the nip portion between the fixing roller 14 and the pressure roller 16, and at this nip portion, heat from the halogen heater 15 provided at the center of the fixing roller 14 and the gap between the rollers. The image is fixed by pressure. Further, during this period, the unnecessary toner left untransferred on the surface of the photosensitive drum 6 after the transfer is cleaned by the cleaning blade 1.
It is scraped off from the surface of the photosensitive drum 6 by 2 and collected in the waste toner container 11. Further, in the above description, the toner leakage prevention sheet 19a is provided under the cleaning blade 12 and the developing sleeve to prevent toner leakage.
19b is provided.

Further, in the above apparatus, in order to simplify the maintenance of the replacement parts such as the photosensitive drum 6 and the toner container 8, the developing device including the photosensitive drum 6, the developing three 7 and the toner container 8 and the waste toner. A process cartridge B in which a cleaning device including the container 11, the cleaning blade 12, and the charging roller 5 are integrated into a cartridge is used. FIG. 1 shows an example of such a process cartridge B, and FIG. 1 shows a state before such a process cartridge B is attached to a transfer portion on the main body side of the image forming apparatus A, which serves as a toner charging unit. By using a developing blade 7'made of urethane resin, the photosensitive drum 6 and the developing sleeve 7 are connected by a fulcrum 17 and the whole is held by a cover 18, and the surface of the photosensitive drum 6 is protected and unnecessary exposure by external light is prevented. A drum shutter 20 is provided in order to prevent the photosensitive drum 6 from contacting the photosensitive drum 6 and the transfer roller 10 after the process cartridge B is mounted on the main body of the image forming apparatus A as shown in FIG. Is configured. In order to guide the recording paper 13 to this transfer area at an appropriate position and angle, a pre-transfer guide plate composed of two upper and lower metal plates is required, and as shown in FIG. A plate 21 and a lower guide plate 22 are provided.

The process cartridge is a cartridge in which the charging means, the developing means or the cleaning means and the electrophotographic photosensitive member are integrally formed, and the cartridge can be attached to and detached from the main body of the image forming apparatus. Further, at least one of the charging means, the developing means, and the cleaning means and the electrophotographic photosensitive member are integrally made into a cartridge so that it can be attached to and detached from the main body of the image forming apparatus.
Further, at least the developing means and the electrophotographic photosensitive member are integrally formed into a cartridge so as to be detachable from the image forming apparatus main body.

The process cartridge B described above is designed to be attached to and detached from the cartridge mounting means provided in the image forming apparatus main body 28 as shown in FIG.

The cartridge mounting means is the opening / closing member 2
As shown in FIG. 8, when the cartridge 8a is opened, a cartridge mounting space is provided, and a cartridge mounting guide portion 35 is provided on the left and right inner side surfaces of the apparatus main body 28. A first guide rail 35a and a second guide rail 35 for inserting the process cartridge B into the left and right guide portions 35.
b are provided facing each other. On the other hand, on both outer side surfaces of the process cartridge B, there are provided cylindrical protrusions 35c protruding outward from the rotation center position of the photosensitive drum 6 and having a radius substantially the same as the groove portion 35a1 provided at the end portion of the first guide rail 35a. Also, a guide ridge 35d is provided continuously to the cylindrical protrusion 35c. Further, an engaging portion 35e is provided on the lower front side in the insertion direction of the process cartridge B.

When the process cartridge B is mounted, the cylindrical protrusion 35c of the process cartridge B is attached.
The guide ridge 35a is guided by the first guide rail 35a, and the engaging portion 35e is guided by the second guide rail 35b.
The cylindrical protrusion 35e
Fits into the groove 35a1. Then, the process cartridge B is attached to the image forming apparatus A by closing the opening / closing member 28a.

In the above description, the first guide rail 35a and the second guide rail 35b of the left and right guide portions 35 are shown in FIG.
The image forming apparatus main body 28 of FIG. 8 is provided so as to be curved from the upper right to the lower left diagonally so that the upper side is concave. When the process cartridge B is attached to the image forming apparatus A from the upper right to the lower left. , Go straight and rotate so that the inclination angle becomes smaller. Then, it is removed in the opposite direction to the above.

In the present embodiment a, the photosensitive drum 6 is provided with the protrusions 23 at the left and right ends as viewed from the feeding direction of the recording paper 13.
A cartridge fixing upper guide plate 21 fixed to the process cartridge B side at a desired position and angle accurately positioned with respect to the center of the cartridge and a drum shutter 20 downsized accordingly are provided. The lower guide storage plate 2 is attached to the rotary shaft 24a that is fixedly installed on the right side of the paper feed side in FIGS.
4 is swingably supported. The lower end on the transfer side is supported by the pressure spring 25 supported on the image forming apparatus main body 28 side, so that the lower guide storage plate 24 is held at an appropriate position and angle. The lower guide storage plate 24 is provided with a guide portion 24b parallel to the conveyance direction of the recording paper 13. The other end is connected to an elastic body 24 'of a stretchable tension coil spring, one end of which is coupled to the inner bottom of the guide portion 24b, and the left and right end portions are movable in the front-back direction within the stretchable range of the elastic body 24'. A movable lower guide plate 22 having a groove 22 'is movably fitted in a guide portion 24b of a lower guide storage plate 24.

While the process cartridge B is slid obliquely downward as indicated by the white arrow in FIG. 1, the process cartridge B is pushed downward by rotating it as indicated by the black arrow in FIG. The protrusions 23 at the lower left and right ends push down the movable lower guide plate 22 against the spring force of the pressure spring 25, and slide on the surface of the movable lower guide plate 22 and engage with the grooves 22 'at the left and right ends thereof. The gap necessary for passing the recording paper 13 is secured and integrated, and the movable lower guide plate 22 moves against the spring force of the elastic body 24 by following the moving direction of the cartridge fixed upper guide plate 21. The pre-transfer guide plate is set at a position and an angle where a good transferred image can be finally obtained.

When the process cartridge B is removed from the image forming apparatus main body 28 by rotating and moving in the opposite manner to the above, in FIG. 2, the projection 23 of the upper guide plate 21 is retracted and the lower guide plate 22 is also retracted. Then, the protrusion 23 is disengaged from the groove 22 'of the lower guide plate 22, and is retracted against the pressure spring 25, and finally the protrusion 23 is moved to the upper right in FIG.
The lower guide plate 22 is restored by the spring force of the pressure spring 25.

According to the present embodiment, the pre-transfer guide plate is accurately aligned with the photosensitive drum, good transferability is obtained, and a jam occurs while passing through the pre-transfer guide plate. It is possible to provide an image forming apparatus that can easily perform jam processing.

(Embodiment B) FIGS. 4 and 5 are cross-sectional views of a process cartridge and a transfer unit before mounting in an image forming apparatus showing the embodiment B of the present invention, and a process cartridge and a transfer unit after mounting. FIG.

The upper guide / drum shutter 20 'is swingably supported by a four-bar linkage using the process cartridge B as a fixed link. That is, the other end of the arm 26, which is a link whose one end is pivotally attached to the drum shaft 6a that is fixed to the frame body of the process cartridge B and rotatably supports the photosensitive drum 6, has the other end of the arm shutter 26 which also serves as the upper guide.
0'is connected to the front end side in the insertion direction of the process cartridge B by a pin 26a, one end is connected to the side surface of the frame of the process cartridge B by a pin 34, and the other end of the link 36 is a pin 37 at the other end. 20 'is connected to the rear end side in the insertion direction of the process cartridge B, and is connected to the upper shutter / drum shutter 21 by a spring (not shown).
Is biased in the direction of closing the transfer opening 38. With this configuration, the upper guide / drum shutter 20 'is
When it is supported by the arm 26 and the link 36 and swings forward, it comes to the position shown in FIG. 4 and covers the photosensitive drum 6. Then, when it swings rearward, the position becomes as shown in FIG. 5, and the transfer opening 38 of the photosensitive drum 6 is opened.

4 and 5, members designated by the same reference numerals as those in FIG. 1 indicate the same constituent elements. In the present embodiment (b), instead of the cartridge fixing upper guide plate 21, an upper guide / drum shutter 20 'having the same function as this upper guide plate is used. This drum shutter 20' is as shown in FIG. By sliding the process cartridge diagonally downward in the direction of the white arrow and simultaneously hitting the middle of the arm 26 against a protrusion (not shown) on the side of the cartridge mounting portion, the arm 26 is rotated counterclockwise in FIG. The drum shutter 20 ′ is moved and opened rearward as shown by a black arrow while the tip portion of the drum shutter 20 ′ is connected to the drum shaft 6 a at the center of the photosensitive drum 6 by the arm 26, and is rotated as shown by a black arrow in FIG. 5. Then, the process cartridge B is pushed downward, and thereafter, as in the case of the above-mentioned Embodiment A, the left and right sides of the upper guide / drum shutter 20 'are both pushed. The lower protrusion 23 slides on the surface of the movable lower guide plate 22 and engages with the grooves 22 'at the left and right ends of the movable lower guide plate 22 to secure a gap necessary for passing the recording paper 13 and is integrated therewith. When the movable lower guide plate 22 moves following the moving direction of 20 'and the upper guide / drum shutter 20' comes to a position and angle where a good transferred image can be finally obtained, the arm 26 moves the process cartridge. The drum shutter 2 is accurately positioned by the stopper 27 fixed to the frame body of B.
A part of 0'functions as a pre-transfer guide plate with high accuracy.

In FIG. 5, when the process cartridge B is removed from the image forming apparatus main body 28, the protrusion 23 of the upper guide / drum shutter 20 ′ is disengaged from the groove 22 ′ of the lower guide plate 22, and the protrusion 23 is removed. When the arm 26 slides upward and retracts, the arm 26 rotates clockwise and the upper guide / drum shutter 20 ′ closes the transfer opening 38, and when the projection 23 separates from the lower guide plate 22, the drum shutter 20 ′ moves. 20 'is fully opened.

According to the embodiment B, the pre-transfer guide plate is accurately aligned with the photosensitive drum, good transferability is obtained, and a jam occurs while passing through the pre-transfer guide plate. It is possible to provide an image forming apparatus that can easily perform jam processing, and since the drum guide also serves as the upper guide plate as compared with the embodiment a, it is possible to obtain the same effect by reducing the number of parts. Like

As the pressing spring 25 at the lower part of the lower guide plate used in each of the above embodiments, a spring having a spring pressure strength in the range of 500 gf to 1 kgf when the process cartridge B is mounted is used. It prevents the process cartridge B from colliding strongly with the lower guide plate 22 due to an appropriate repulsive force from the image forming apparatus main body 28 side when the cartridge B is attached or detached, and when the process cartridge B is removed, the pressure spring 25 Has a function of assisting the removal work of the process cartridge B by urging the process cartridge B in the removal direction.

(Embodiment C) FIGS. 6 and 7 show the case where thin and weak recording paper of an image forming apparatus and thick and strong recording paper of an image forming apparatus respectively representing Embodiment C of the present invention are passed. FIG. 3 is a cross-sectional view of the process cartridge and the transfer unit after being attached to the image forming apparatus main body 28 of FIG. In FIG. 6, members designated by the same reference numerals as those in FIG. 4 indicate the same constituent elements, and in the present embodiment C, the pressure spring 25 of the movable lower guide plate 22 is set to the thin recording paper 13 'having a weak waist and the waist having a strong waist. When a thick recording paper 13 ″ is passed, a delicate difference in force for pushing down the movable lower guide plate 22 generated from the contact portion between both the upper guide / drum shutter 20 ′ and the photosensitive drum 6 and the recording paper is passed. It uses a light pressure spring 25 'that can swing up and down according to
Although the spring pressure strength at this time depends on the weight of the movable lower guide plate 22, a spring having a spring constant of 10 to 20 g / mm is used, and when the process cartridge B is mounted, the upper guide / drum shutter 20 'is finally used. The height relationship of each member is set so that the movable lower guide plate 22 is lifted to a height equal to or higher than the height before mounting the cartridge.

Usually, there are various kinds of papers used as the recording paper 13, and generally, the thin paper having a weight of 60 g per square meter and the thick paper having a weight of 128 g per square meter, the latter is more flexible. It tends to be strong, and it becomes difficult to smoothly pass through a minute gap formed between the upper and lower guide plates and the surface of the photosensitive drum immediately before transfer. Conventionally, if you force thick paper to pass in such a state,
There is a risk of unwanted charging and surface roughness due to paper deformation and rubbing, and especially the behavior of the leading edge of the paper tends to be disturbed during transport, making it difficult to introduce the paper into the transfer nip at an appropriate angle. Therefore, there is a possibility that a jam may occur or the image quality of the transferred image may deteriorate. For this reason, in the conventional device, in order to simplify the configuration, the setting position of the pre-transfer guide plate is set to a position where it is easy to pass thick paper, and the original optimum position and angle for thin paper are set. Since it is inevitable to make settings that deviate from the conditions leading to the transfer area, and because it is necessary to make a large design margin due to the limit of the mounting accuracy of the process cartridge and the main body of the image forming apparatus described above, it is not always the optimum transfer for these recording papers. It didn't serve as a previous guide.

On the other hand, in the present embodiment C, the basic construction of each of the above-mentioned embodiments is effectively utilized, and the transfer image quality of thin recording paper can be formed to be the highest by optimizing the strength of the spring pressure. Optimum for realizing optimum pre-transfer guide conditions, allowing smooth passage of thick recording paper, and forming the highest quality transfer image for that recording paper within that range. Pre-transfer guide conditions are automatically set according to the stiffness of the recording paper itself, so regardless of the type of recording paper, you can always obtain a high-quality transfer image under optimal conditions. be able to.

[0054]

As described above, according to the present invention, since the pre-transfer guide means is composed of the upper guide plate provided on the process cartridge side and the lower guide plate provided on the image forming apparatus main body side, Even if a paper jam occurs while the recording medium passes through the pre-transfer guide means, it is possible to easily deal with the paper jam only by removing the process cartridge. Further, since the pre-transfer guide means is automatically arranged at the optimum position simply by mounting the process cartridge on the image forming apparatus main body, the conveyance of the recording medium to the transfer area is always realized at the optimum position and angle. A high-quality transferred image can be stably obtained without paying attention to the assembly accuracy and the combination of the image forming apparatus main body and the process cartridge. Further, by using the drum shutter and the upper guide plate in common, the structure of the process cartridge can be simplified because it has the above-mentioned functions.

Further, since the movable lower guide plate is provided with the elastic member which appropriately pressurizes according to the strength of the waist of the recording medium,
It is possible to provide the optimum transfer guide means for thin and thick recording media.

[Brief description of the drawings]

FIG. 1 is a vertical cross-sectional view showing the periphery of a process cartridge and a transfer unit before being attached to an image forming apparatus main body according to an embodiment of the present invention.

FIG. 2 is a vertical cross-sectional view showing the periphery of the process cartridge and the transfer unit after being mounted on the image forming apparatus main body according to the embodiment A of the present invention.

FIG. 3 is a vertical sectional view showing a schematic configuration of an image forming apparatus.

FIG. 4 is a vertical cross-sectional view showing the periphery of the process cartridge and the transfer unit before being attached to the image forming apparatus main body according to the embodiment B of the present invention.

FIG. 5 is a vertical cross-sectional view showing the periphery of the process cartridge and the transfer unit after being mounted in the image forming apparatus showing the embodiment B of the present invention.

FIG. 6 is a vertical cross-sectional view showing the periphery of the process cartridge and the transfer unit before being mounted in the image forming apparatus showing the embodiment C of the present invention.

FIG. 7 is a vertical cross-sectional view showing the periphery of the process cartridge and the transfer unit after being mounted in the image forming apparatus showing the embodiment C of the present invention.

FIG. 8 is a perspective view showing a process cartridge mounting portion of the image forming apparatus main body.

[Explanation of symbols]

1 ... Laser diode 2 ... Polygon mirror 3 ... Lens 4 ... Folding mirror 5 ... Charging roller 6 ... Photosensitive drum 6a ... Drum shaft 7 ... Developing sleeve 7 '... Developing blade 8 ... Toner container 9 ... Toner 10 ... Transfer roller 11 ... Disused Toner container 12 ... Cleaning blades 13, 13 ', 13 "... Recording paper 14 ... Fixing roller 15 ... Halogen heater 16 ... Pressure roller 17 ... Support point 18 ... Covers 19a, 19b ... Toner leak prevention sheet 20 ... Drum shutter 20' ... Upper guide / drum shutter 21 ... Cartridge fixed upper guide plate 22 ... Movable lower guide plate 22 '... Groove 23 ... Protrusion 24 ... Lower guide storage plate 24a ... Rotating shaft 24b ... Guide part 24' ... Elastic body 25 ... Pressing spring 25 '... Light pressure spring 26 ... Arm 26a ... Pin 27 ... Stopper 28 ... Image type Apparatus main body 28a ... opening and closing member 34 ... pin 35 ... cartridge mounting guide 35a ... first guide rail 35a1 ... groove 35b ... second guide rail 35c ... cylindrical projections 35
d ... Guide ridge 35e ... Engaging portion 36 ... Link 37 ... Pin 38 ... Transfer opening A ... Image forming device B ... Process cartridge

Claims (14)

[Claims] 1. A process cartridge having an electrophotographic photosensitive member and process means acting on the electrophotographic photosensitive member, which is detachable from an image forming apparatus main body, and an image formed on the electrophotographic photosensitive member as a recording medium. Transfer means for transferring on top,
In an electrophotographic image forming apparatus having a pre-transfer recording medium guide means for guiding the recording medium to the electrophotographic photosensitive member and the transfer means, the pre-transfer recording medium guide means is provided in a process cartridge. An electrophotographic image forming apparatus comprising: an upper guide plate and a lower guide plate provided on the main body of the image forming apparatus. 2. The lower guide plate is provided so as to be movable in the vertical direction and the front-rear direction which is substantially the same direction as the recording medium transport direction, and the upper guide plate is used when the process cartridge is mounted on the image forming apparatus main body. A positioning means for engaging with the lower guide plate to secure a gap required to convey the recording medium between the upper and lower guide plates and for moving the upper and lower guide plates to a desired position and angle. The electrophotographic image forming apparatus according to claim 1. 3. The guide unit for the recording medium before the transfer,
An upper guide plate having a downward projection on at least one of the left and right end portions, and an upper and lower movable portion provided on the image forming apparatus main body side in the front-rear direction which is substantially the same as the conveyance direction of the recording medium and at least the left and right end portions One of them is a lower guide plate having a groove that meshes with a protrusion provided on the upper guide plate, and when the process cartridge is mounted on the image forming apparatus main body, the protrusion provided on the upper guide plate has the lower guide plate. The lower guide plate is moved to a desired position and angle according to the movement of the upper guide plate while engaging with a groove provided in the plate to secure a gap required to convey the recording medium between the upper and lower guide plates. The electrophotographic image forming apparatus according to claim 2, wherein the electrophotographic image forming apparatus is set as follows. 4. A mounting means for mounting the process cartridge in a diagonally downward direction, wherein a protrusion provided on the upper guide plate is mounted on the lower guide plate in accordance with an operation for mounting the process cartridge in a diagonally lower front direction. 4. The electrophotographic image forming apparatus according to claim 3, wherein the electrophotographic image forming apparatus operates so as to push it down and pull it out forward. 5. The upper guide plate is configured to be movable so as to cover the surface of the electrophotographic photosensitive member when the process cartridge is not mounted and also serve as a shutter that can open the surface of the electrophotographic photosensitive member when the process cartridge is mounted,
4. The electronic device according to claim 3, wherein the protrusion of the upper guide plate moves the upper guide plate with respect to the electrophotographic photosensitive member in a direction of opening the surface of the electrophotographic photosensitive member while acting on the lower guide plate. Photo image forming apparatus. 6. The storage plate, wherein the lower guide plate has a sheet feeding side end portion fixed to a rotatable rotation shaft and a transfer side end portion that is pushed upward by a pressing unit about the rotation shaft, 6. The recording medium according to claim 2, wherein the recording medium is movably fitted in the front-rear direction substantially the same as the conveying direction and is urged forward by an elastic member that is expandable and contractible. Electrophotographic image forming apparatus. 7. The pressurizing means for pushing up the transfer side end portion of the lower guide plate from the lower side to the upper side is constituted by an elastic member capable of expanding and contracting according to the strength of the waist of the recording medium. Item 7. The electrophotographic image forming apparatus described in any one of Items 2 to 6. 8. The electrophotographic photosensitive member has a cylindrical shape, and the set position of the upper guide plate is positioned with reference to the central axis of the cylinder of the cylindrical electrophotographic photosensitive member. Item 8. The electrophotographic image forming apparatus described in any one of Items 2 to 7. 9. A transfer unit for transferring an image formed on an electrophotographic photosensitive member onto a recording medium, and a recording medium before transfer for guiding the recording medium to the electrophotographic photosensitive member and the transfer unit. In a process cartridge detachably mountable to an electrophotographic image forming apparatus having a guide unit, the process cartridge having the electrophotographic photosensitive member and a process unit acting on the electrophotographic photosensitive member, the guide unit for the recording medium before transfer is A guide plate,
A process cartridge comprising a lower guide plate, wherein the upper guide plate is included in the process cartridge. 10. A transfer unit for transferring an image formed on an electrophotographic photosensitive member onto a recording medium, and a recording medium before transfer for guiding the recording medium to the electrophotographic photosensitive member and the transfer unit. In a process cartridge, which is detachably mountable to an electrophotographic image forming apparatus having a guide means and has the electrophotographic photoreceptor and a process means acting on the electrophotographic photoreceptor, the guide means for the recording medium before transfer is a process The upper guide plate is fixed to the cartridge, and the lower guide plate is provided in the main body of the image forming apparatus so as to be movable up and down and in the front-rear direction which is substantially the same as the conveyance direction of the recording medium. When the process cartridge is mounted on the main body of the image forming apparatus, a gap necessary for engaging the lower guide plate to convey the recording medium between the upper and lower guide plates is provided. A positioning means for moving said lower guide plate to a desired position and angle while holding the process cartridge comprises said electrophotographic photosensitive member. 11. The upper guide plate covers the electrophotographic photosensitive member when the process cartridge is not attached to the image forming apparatus main body, and engages with the lower guide plate when the process cartridge is attached to the image forming apparatus main body to open the electrophotographic photosensitive member. The process cartridge according to claim 9 or 10, wherein 12. The process cartridge comprises a charging means, a developing means or a cleaning means, and an electrophotographic photosensitive member integrally formed as a cartridge, and the cartridge can be attached to and detached from the main body of the image forming apparatus. 10. The process cartridge according to 10 or 11. 13. The process cartridge, wherein at least one of a charging unit, a developing unit, and a cleaning unit and an electrophotographic photosensitive member are integrally made into a cartridge so as to be attachable to and detachable from the main body of the image forming apparatus. 10. The process cartridge according to 10 or 11. 14. The process cartridge, wherein at least a developing means and an electrophotographic photosensitive member are integrally made into a cartridge so as to be attachable to and detachable from the image forming apparatus main body.
Alternatively, the process cartridge according to 10 or 11.