JP2002311796A - Process cartridge and image forming apparatus provided with the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a sheet from being made dirty. SOLUTION: The process cartridge 31 is provided with a photoreceptor 1 capable of carrying an image to be formed on a carried sheet, a lower surface 31a of the process cartridge 31 arranged on the downstream side in the recording medium carrying direction of the photoreceptor body 1 for guiding a recording medium to be carried to a fixer 7 and a plurality of spurs 40a, 40b and 40c arrayed between the photoreceptor 1 and the fixer 7 and a plurality of spurs 40a, 40b and 40c are arrayed on the side of the lower surface 31a of the process cartridge 31 rather than a line (k) connecting a sheet passing part N1 of the photoreceptor 1 and a sheet passing part N2 of the fixer 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process cartridge having an image carrier for carrying an image for forming an image on a sheet, and an image forming apparatus provided with the process cartridge in an apparatus main body.

[0002]

2. Description of the Related Art An image forming apparatus for forming an image on a recording medium using an electrophotographic image forming process includes, for example, an electrophotographic copying machine, an electrophotographic printer (for example, an LED printer, a laser beam printer, etc.), an electrophotographic printer, and the like. There are facsimile machines, electrophotographic word processors, and the like.

Conventionally, in FIG. 18, a process cartridge 71 includes, for example, a photosensitive member 1, a primary charger 72 for uniformly charging the photosensitive member 1, and a transfer medium 73 for transferring a toner image on the photosensitive member 1 to a recording medium P. After transfer to
The cleaning unit 33 for removing the residual toner is integrally provided, and is detachably provided to the apparatus main body of the copying machine by a rail 74 on the process cartridge side and a rail 75 on the copying machine side.

[0004] In addition to the process cartridge 71,
Some photoreceptors, a primary charger, and a developing device that develops a latent image formed on the photoreceptor with a developer such as toner are integrated with each other, and are detachably provided in an apparatus body of a copying machine.

The recording medium P on which the unfixed toner image has been transferred
Before the recording medium P reaches the fixing device 7 having the heat fixing roller 76 and the pressure roller 77, the rear end side in the transport direction of the recording medium P jumps up, and is located somewhere close to the transport path space (here, the code on the lower surface of the process cartridge). g range), which may disturb the unfixed toner image.

[0006] When the rear end of the recording medium P in the transport direction passes through the transfer charger 73 and is attracted electrostatically, the transport speed of the fixing unit 7 is controlled so that the recording medium P does not wrinkle. Since the outer side is set slightly faster, the rear end of the recording medium P in the conveyance direction passes through the transfer charger 73 because the distortion increases as the conveyance progresses.
This occurs when the recording medium P is released, when the rear end of the recording medium P in the transport direction approaches the press-contact portion (nip) of the fixing unit, and becomes distorted.

In general, as shown in FIG. 19, in order to prevent the unfixed toner image from being disturbed by the jump, the recording medium P rotates by contacting and moving, and The recording medium P is guided by star-shaped spurs 40e and 40f having a reduced contact area.

However, if the copying machine is operated for a long time,
9 is used in an insufficiently cleaned state, or when used in an environment of high temperature and high humidity, the recording medium P after transfer is
Not completely separated from the recording medium P
May collide with the spurs 40e and 40f and cause a paper jam (jam). A copier that prevents this is disclosed in Japanese Patent Application Laid-Open No. 2000-147797. As shown in FIG.
e, a guide rib 78 for guiding the recording medium P so as not to collide with 40f.

[0009]

However, it has been found that, in the conventional copying machine shown in FIG. 19, the toner adheres to the guide ribs 78 over a long period of use, and the recording medium P is soiled.

The reason is that the toner image on the photoreceptor 1 is transferred to the recording medium P by the transfer charger 73, and the recording medium P is separated from the photoreceptor 1 by the separation / elimination unit 79. Unfixed toner images contain electrostatically unstable toner, and the unstable and invisible toner particles scatter very slightly, resulting in long-term use of copiers. Is gradually accumulated in the guide ribs 78.

When the jumping of the recording medium P becomes stronger, the contact force of the recording medium P with the spur becomes too strong, and the toner adheres to the tip of the star-shaped spur, and the toner trace is formed on the recording medium P. It was also found to stick to.

Further, as shown in FIG.
If the distance between the spur 40f and the spur 40f is wide, the recording medium P cannot be delivered from the spur 40e on the upstream side to the spur 40f on the downstream side, and the recording medium P comes into contact with the guide rib 78, and the guide rib 7
It was found that the recording medium P was contaminated by the toner adhering to No. 8.

Further, as shown in FIG. 21, since the bearing 80 of the spur 40e protrudes outside the valley between the star-shaped claws of the spur 40e, the recording medium P comes into contact with the bearing 80. As a result, it was found that the recording medium P was contaminated.

Furthermore, recently, due to the miniaturization of copiers,
The recording medium P per unit time is used in order to prevent the parts in the apparatus from being close to each other and to secure a sufficient space between the parts, and to enable the user to discharge the recording medium P in a short time. It is desired to increase the number of output sheets.
For this reason, the length of the conveyance path of the recording medium P tends to be shortened as much as possible, and the interval between the photoconductor 1 and the fixing device 7 is often reduced.

For this reason, the process cartridge 71 and the fixing device 7 inevitably come close to each other, and the jumping of the recording medium P often occurs in the area where the process cartridge 71 exists. The area was easier to contact. Further, when the process cartridge and the fixing device approach each other, the contact force of the unfixed toner surface of the recording medium P tends to be relatively strong even if the same amount of jumps as in the related art occurs.

As described above, the necessity and importance of providing a spur on a transport path such as a process cartridge have been considerably increased.

The present invention relates to a process cartridge which does not stain a sheet, and an image forming apparatus provided with the process cartridge in an apparatus main body.

[0018]

In order to achieve the above object, a process cartridge according to the present invention comprises an image carrier capable of carrying an image formed on a conveyed sheet, and an image carrier in the sheet conveyance direction of the image carrier. Sheet guide means for guiding the sheet conveyed to the sheet convey means provided on the downstream side, and arranged between the image carrier and the sheet convey means, and a plurality of corners formed on an outer periphery; A plurality of sheet conveying rotary members arranged in the sheet conveying direction, wherein the plurality of sheet conveying rotating members are formed by a line connecting a sheet passing portion of the image carrier and a sheet passing portion of the sheet conveying means. It is arranged on the sheet guide means side.

In the process cartridge according to the present invention, the plurality of sheet conveying rotators in the sheet conveying direction are more downstream in the sheet conveying direction than in the sheet conveying direction. It is away from the line connecting the sheet passing portion of the carrier and the sheet passing portion of the sheet conveying means.

In the process cartridge according to the present invention, the interval between the plurality of sheet transport rotary members is more downstream than the interval between the upstream sheet transport rotary members in the sheet transport direction. The distance between them is wider.

In the process cartridge of the present invention, among the plurality of sheet conveying rotating members, two pairs of sheet conveying rotating members on the upstream side in the sheet conveying direction are provided with a sheet passing portion of the image carrier and a sheet conveying member. The rotation center of the adjacent sheet conveying rotating body is located between a line connecting a sheet passing portion and the sheet guiding unit, and is arranged at different positions in a direction crossing the sheet conveying direction. The interval is set to be equal to or less than the sum of the radii of the adjacent sheet conveying rotating members.

Each of the plurality of sheet conveying rotators of the plurality of sheet conveying rotators of the process cartridge of the present invention is arranged in a plurality of directions in a direction intersecting the sheet conveying direction. The number of arrangements of the sheet conveyance rotating body on the downstream side in the sheet conveyance direction is larger than the number of arrangements.

In the process cartridge according to the present invention, at least the most upstream sheet transporting rotator of the plurality of sheet transporting rotators is a spur rotatably supported by rotation supporting means. The portion downstream of the rotation center of the spur is smaller than the valley diameter of the spur.

[0024] The sheet conveying rotating member located at the most upstream side of the process cartridge of the present invention is a sheet conveying rotating member which is formed by a line connecting a sheet passing part of the image carrier and a sheet passing part of the sheet conveying means and the sheet guiding means. It is located between them.

In order to achieve the above object, an image forming apparatus according to the present invention includes any one of the above-described process cartridges, and sheet conveying means for receiving and conveying a sheet that has passed through the process cartridge.

In order to achieve the above object, an image forming apparatus according to the present invention includes any one of the above process cartridges, and sheet transport means for receiving and transporting a sheet passing through the process cartridge. The distance between the image carrier of the cartridge and the sheet conveying means is set shorter than the length of the minimum size sheet among the sheets on which images are formed by the image carrier.

In order to achieve the above object, an image forming apparatus according to the present invention includes any one of the above process cartridges, and sheet conveying means for receiving and conveying a sheet that has passed through the process cartridge. The conveying means is a fixing device for fixing an image transferred by the process cartridge to the sheet.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A copying machine which is an image forming apparatus according to an embodiment of the present invention will be described below with reference to the drawings. However,
The dimensions, materials, shapes, relative positions, and the like of the components described in this embodiment are not intended to limit the scope of the present invention only to them unless otherwise specified.

First, the overall structure of the copying machine 81 will be described with reference to FIG. The apparatus main body 82 of the copying machine 81 includes a scanner unit 83 for reading image information on the image surface of a book document, an image forming unit 84, and a recording medium deck 8 in order from the top to the bottom.
Five.

The scanner unit 83 includes a scanning system light source 61, a platen glass 62, a document pressure plate 63 that can be opened and closed with respect to the apparatus main body 82, a first mirror 64, a second mirror 65, a third mirror 66, a lens 67, and a light receiving unit. Element (photoelectric conversion element)
68 and an image processing unit.

The scanning system light source 61 and the first mirror 64 constitute a first mirror base, and the second mirror 65 and the third mirror 66
Constitutes a second mirror base and is scanned in the scanning direction a.
In addition, the moving state of the first mirror base and the second mirror base is indicated by a dotted line.

Then, the user places the original on a platen glass 62 with the original surface of a book original such as a book, thick paper, curled paper or the like or a sheet original on the platen glass 62 facing downward (the platen glass 62 side). When the original is set in a stationary state in which the rear surface of the original is pressed by the original pressing plate 63 and then a reading start key of an operation unit (not shown) is pressed, the scanning system light source 61 scans the lower part of the platen glass 62 in the direction of arrow a to copy the original. And the reflected light is guided to the first mirror 64.

The image information of the document guided to the first mirror 64 passes through the second mirror 65 and the third mirror 66 to the lens 67.
Is projected onto the light receiving element 68, the image information is read by the light receiving element 68, and processed by an image processing unit (not shown).
The signal is converted into an electric signal and transmitted to the laser scanner 69 of the image forming unit 84.

Here, the apparatus body 82 of the copying machine functions as a copying machine when the processing signal of the image processing section is input to the laser scanner 69, and functions as a printer when the output signal of the personal computer is input. When a transmission signal from a facsimile device of another device is input or a processing signal of the image processing unit is transmitted to a facsimile device of another device, the device functions as a facsimile device.

On the other hand, below the image forming section 84, a sheet cassette 21 containing a recording medium P is provided. The sheet cassette 21 includes a lower cassette 21a and an upper cassette 21b, and is configured as one feeding unit.

The recording media contained in the lower cassette 21a and the upper cassette 21b are fed out by the pickup roller 22, and separated and fed one by one by the cooperation of the feed roller 23 and the retard roller 24. Thereafter, the sheet is conveyed by the conveying roller pairs 25, 26, 27.

Then, the conveyed recording medium is stopped for a predetermined time so that the recording medium is adjusted by the pair of pre-registration rollers 28, and then rotated to convey the recording medium.
Further, the transport roller pair 10 sends the recording medium to the registration roller pair 11. The registration roller pair 11 feeds the recording medium to the image forming unit 84 in synchronization with the image forming operation.

The image forming section 84 includes a photosensitive member (image carrier)
1, an image writing optical system 2, a developing unit 3, a transfer roller 6 of a transfer unit 4, and the like. Then, a laser beam corresponding to image information emitted from the laser scanner 69 is scanned by the image writing optical system 2 on the surface of the photoconductor 1 uniformly charged by the primary charger 5 to form a latent image. This latent image is converted into a toner image by the developing device 3.
The toner image is transferred by the transfer roller 6 to the first surface of the recording medium conveyed in synchronization with the rotation of the photoconductor 1 by the registration roller pair 11.

On the downstream side in the transport direction of the image forming section 84, a recording medium guide 19, a fixing device (sheet transport means) 7, and a discharge roller pair 12 are sequentially arranged. The recording medium on which the toner image has been formed is guided to a recording medium guide 19 from a transfer unit (transfer unit) 86 formed by the photoconductor 1 and the transfer roller 6, and is conveyed to the fixing device 7. The fixing device 7 heats and pressurizes the recording medium to fix the toner image on the surface of the recording medium.

The recording medium after fixing is guided in the discharge direction, and is stacked by a discharge roller pair 12 on a discharge tray (upper part of the image forming section 84) 13 having a function as a top cover. The recording medium is placed on the discharge tray 13.
The paper is discharged face down with the image forming surface down.

The case where an image is formed on the opposite surface of the recording medium will be described.

The pair of discharge rollers 14 and 12 convey the recording medium that has passed through the fixing device 7, and immediately after the trailing end of the recording medium has passed through the flapper 15, rotate in reverse while holding the recording medium to remove the recording medium. The recording medium is once placed on the recording medium double-sided tray 16 after being inverted (turned over). afterwards,
Each roller pair 28 and 10 conveys the recording medium and sends it to the registration roller pair 11. After an image is formed on the second surface of the inverted recording medium in the same manner as described above,
3 and loaded.

A pre-registration sensor lever 17 for detecting the recording medium is provided upstream of the pair of registration rollers 11 in the conveying direction of the recording medium. The pre-registration sensor lever 17 rotates when the recording medium is conveyed. The sensor 18 is activated by the rotation of the pre-registration sensor lever 17, detects the presence of the recording medium, and notifies the CPU of the image forming apparatus main body thereof.

As shown in FIG. 2, the process cartridge 31 includes a charging roller 32 of the primary charger 5, a cleaning unit 33 for scraping residual toner on the photosensitive member 1, and a cleaning unit 33 for scraping residual toner on the photosensitive member 1. It has a screw 34 to be fed to the back side along the axial direction, and a shutter 35 constantly urged in the closing direction to protect the photoconductor 1.

The shutter 35 is connected to the process cartridge 3
When the recording medium is jammed in the vicinity of the registration roller 1 or the pair of registration rollers 11, the transport unit 49 is released by rotating the lever 48 in the direction of the arrow as shown in FIG.
It is provided to protect the photoreceptor 1 from being damaged when a clogged recording medium is removed by inserting a hand.

When the lever 48 is returned, the shutter 35 retreats to the position shown in FIG. Process cartridge 31
Can be attached to and detached from the apparatus body 82 of the copying machine. The process cartridge 31 can be attached and detached by a left rail 36 and a right rail 37 provided on the process cartridge 31, and a left rail 38 and a right rail 39 of the apparatus main body 82 supporting the rails 36 and 37. It has become.

As shown in FIG. 1, there are three rows of spurs 40, and spurs (sheet conveying rotating bodies) 40a, 40b and 40c are arranged from the upstream side in the conveying direction of the recording medium. The spur 40 can rotate smoothly when the recording medium comes into contact with it, and is made of resin.

As a factor of the rear end of the recording medium jumping,
The case where the static elimination needle 45 is insufficiently cleaned due to long-term use of the copying machine 81, the environment in which the copying machine 81 is used, the direction of the gap of the recording medium, the strength of the waist, the size, the type, the moisture absorption state, and the like. Can be It has been found that the jumping-up phenomenon is likely to occur when various conditions such as a gap in a direction perpendicular to the conveyance direction, a stiff body, recycled paper, and a low-humidity environment are overlapped.

The fixing unit 7 includes a driving-side pressure roller 41,
It has a driven-side endless fixing film 42 on the driven side and a heater 43 inside the fixing film 42, and records an unfixed toner image on the pressure contact portion (nip N 2) between the pressure roller 41 and the film 42. The heat is fixed by passing through the medium. Since the pressure roller 41 expands due to the influence of the heater 43 and the conveyance speed of the fixing increases, the cycle of the fixing film 42 is detected by the sensor 50, and the CPU controls the speed so that the conveyance speed becomes appropriate.

The spurs 40a, 40b, and 40c have spurs having a nip (a sheet passing portion of the image carrier) N1 between the photosensitive member 1 and the transfer roller 6, and a nip (a nip) between the fixing film 42 and the pressure roller 41. Sheet passing part of sheet conveying means)
It is arranged above the tangent k connecting N2 (on the side of the process cartridge 31). Even if the recording medium moves upward and passes through a place close to the tangent k, recording is performed. It does not come into contact with the medium.

Further, in FIG. 1, the spurs 40a, 40
b, the distance between the outer (outer diameter) position of 40c and the tangent k is a
Assuming that 1, b2 and c3, a1 <b2 <c3 is set. This is because, in FIG. 4, after the rear end of the recording medium P passes through the transfer roller 6, the distortion applied to the recording medium by the nip N2 of the fixing device 7 is instantaneously released, and comes into contact with the lowermost spur 40a. That's why. After exiting the transfer roller 6, the rear end of the recording medium is moved to the nip N of the fixing device 7.
2, the rear end of the recording medium gradually jumps upward again under the influence of the shape of the nip N2 of the fixing device 7, so that the spurs 40b and 40c
The spurs are arranged at a1 <b2 <c3 so that the outer shape of the spurs is gradually separated from the tangent k so as not to increase the contact force with the spurs.

The contact force of the recording medium to the spurs is strong at the lowermost spur 40a, and the number of spurs is set to be as small as possible to minimize the contact portion of the spur train having the strongest contact force with the recording medium. As shown in FIG. 5, the number of spurs 40a is at least two, the number of spurs 40b is five, and the number of spurs 40c is
Are five. Each spur is arranged along the photoconductor 1. The interval between the spurs 40a is about 130 mm, which is shorter than the minimum paper passing size other than government-made postcards and 139.7 mm, which is the overseas paper, STATEMENT.
Is set to The other spurs 40b and 40c are appropriately arranged so as to guide the ends of various sizes.

Since the recording medium P is electrostatically attracted to the photoconductor 1 and the toner image on the photoconductor is transferred by the transfer roller 6, the curvature separation and the discharge needle 45 away from the arc surface of the photoconductor 1 are performed. Are transported separately by the static elimination effect of The unfixed toner on the recording medium immediately after the transfer includes
Some are invisible, minute, and have an unstable adhesion to the recording medium.
Due to long-term use, the toner may accumulate in the area indicated by the symbol F on the lower surface (sheet guiding means) 31a of the process cartridge 31.

When the state where the toner is accumulated on the lower surface of the process cartridge 31 and the case where the recording medium jumps greatly overlap, it is also found that the trailing end of the recording medium scrapes the accumulated toner and soils the recording medium. (FIG. 6). In order to prevent such a situation from occurring, an auxiliary spur 40d is provided on the upstream side in the transport direction of the spur 40a, in the same row as the spur 40a (FIG. 7).

The spur 40a and the spur (rotating body for sheet conveyance) 4
0d is disposed so as to overlap or touch when viewed from the direction perpendicular to the recording medium conveyance direction (the end face side of the spur shaft). That is, the rotation center interval (L) between the adjacent spurs 40a and 40d is set to be equal to or less than the sum of the radii (d1, d2) of the adjacent spurs 40a and 40d.

The extension of the tangent g (see FIG. 8) connecting the outer shapes of the spurs 40a and 40d is located below the lower surface 31a of the process cartridge 31. As a result, the spurs 40a and 40d are arranged so that the recording medium does not come into contact with the range F which is a stainable area. FIG. 14 shows a view of the spurs 40a and 40d viewed from below. In addition to the arrangement shown in FIG. 5, six spurs 40d are provided so as to be compatible with recording media of each size.

Further, by changing the lower end position of the spur in the same spur train, the rear end of the recording medium having a larger size such as A3 size as shown in FIG.
Even when both ends are upwards, the upwards facing both ends
The contact force with the spur 40d is weakened without rubbing on the spur 1a, thereby helping to prevent image defects.

In FIG. 8, the diameter of the spur 40d is
0a, but as shown in FIG.
A similar effect can be obtained by disposing spurs of the same diameter slightly upstream. However, the spurs 40a and 40d shown in FIG.
10, when the positional relationship is set to a value that is more than an overlapping or invisible distance when viewed from a direction intersecting the conveying direction of the recording medium, and further apart, as shown in FIG. When the rear end of the recording medium jumps after passing through the side spur 40d, there is a possibility that the end of the recording medium P comes into contact with the rotation supporting portion 51 of the spur 40d to which the toner is attached, thereby causing contamination. Maybe.
For this reason, the interval between the spurs 40a and 40d shown in FIG. 9 is set such that the rear end of the recording medium does not contact the rotation support portion 51.

Therefore, when the positional relationship between the spurs is viewed from the direction perpendicular to the recording medium conveyance direction, the spurs are arranged to be shifted left, right, up and down.

Further, the diameter of the spur 40a and the diameter of the spur 40d may be set so as to overlap or be in contact with each other when viewed from the direction perpendicular to the recording medium conveyance direction (FIG. 11). Even when the spurs 40a and 40d are separated by more than the position shown in FIG. 11, as shown in FIG. 12, a substantially star-shaped spur is located within the range F of the process cartridge 31 and the process cartridge 31 which is close to the recording medium transport path. 40a, 4
0d and the rotation supporting portion 51 of the spur.
A portion 51a downstream of the rotation center of the first spur 40d (a portion corresponding to the rear end passage side region h in the recording medium conveyance direction) 51a is
By making the shape smaller than the valley diameter φd of the star spur 40d, the recording medium that jumps up even if toner adheres to the rotation support part 51 of the spur 40d can be rotated.
, The toner adhesion to the recording medium can be minimized only by contacting the tip of the claw 87 of the spur 40d or the valley 88 between the claws.

That is, since the rotation supporting portion 51 is a fixed member, the toner is more likely to adhere than the rotating spur 40d, and it is not preferable that the recording medium is brought into contact with the fixed supporting portion 51. In addition, due to the sliding of the spur 40d and the fixed support portion 51 due to the rotation of the spur 40d, static electricity is generated in the fixed support portion 51, so that the toner easily adheres. However, even if the recording medium comes into contact with the tip of the claw 87 or the valley 88 between the claws of the spur 40d,
Since d rotates following the moving recording medium, static electricity hardly occurs, and toner hardly adheres. For these reasons, as shown in FIG.
The toner adhesion to the recording medium can be minimized only by contacting the tip of the nail or the valley between the nails.

The downstream end 52a of the rotary support 52 supporting the spur 40a on the downstream side has the same effect as the downstream end 51a of the rotary support 51 supporting the spur 40d. (Figure 13).

That is, the portion 52a downstream of the rotation center of the spur 40a of the rotation supporting portion 52 (the portion corresponding to the rear end passing side region h in the recording medium conveyance direction) is set to a range smaller than the valley diameter φd of the star spur 40a. When the toner adheres to the rotation supporting portion 52 of the spur 40a, the recording medium that has jumped up does not contact the rotation supporting portion 52, and the tip of the claw 89 of the spur 40a or the valley 90 between the claws. The toner contact on the recording medium can be suppressed to a minimum simply by contacting the recording medium.

Further, in the copying machine of the present embodiment, the components in the apparatus are brought closer to each other by downsizing, the output of the recording medium is shortened by a user operation, and the recording medium transport path for improving the productivity of the recording medium is improved. By shortening the distance, the distance between the photoconductor and the fixing device is shortened, and a line k connecting the nip N2 of the photoconductor 1 and the fixing device 7 is formed.
(Fig. 1) The length of the postcard is about 95mm, which is 140mm, which is the minimum size of a domestic government-manufactured paper.
(Statement) The distance is shorter than 139.7 mm. In the copier having such a configuration, since the jumping of the recording medium often occurs in the area provided with the process cartridge, the arrangement and configuration of the spur provided in the process cartridge 31 of the present embodiment are quite effective. Will work.

As for the spurs, all the process cartridges 3
1, the same effect can be obtained by providing a spur 47 on the fixing entrance upper guide 46 as shown in FIG.

As described above, in the arrangement of the spur train of the copying machine of this embodiment, the spurs 40a, 40b, 40c
Is arranged above the tangent line k connecting the photosensitive member 1 and the film 42 (toward the photosensitive member 1), thereby pulling the recording medium due to an increase in the fixing conveyance speed due to heat. Even if a situation close to the tangent line k occurs, a good image can be maintained without spurs.

The distances a1, b2, and c3 between the outer (outer diameter) positions of the spurs 40a, 40b, and 40c and the tangent line k are represented by a1.
By arranging in the relationship of <b2 <c3, even if the amount of jumps increases, guidance by spurs can be smoothly performed, and image defects can be avoided.

Further, the positional relationship between the spurs should be such that the outer shapes of the spurs 40a and 40d overlap when viewed from the direction of the drawing, and the extension of the tangent line g connecting the outer shapes is larger than the range F of the lower surface of the process cartridge. By making it outside, it is possible to prevent the trailing edge of the recording medium from being stained even when the toner adheres to the range F on the lower surface of the process cartridge and the case where the jump is large overlaps.

The spur profile in the spur train on the most upstream side in the recording medium transport direction has the closest distance a1 to the profile of the spur train on the downstream side, and the number of spurs is minimized, so that the contact portion with the recording medium is reduced. Can be reduced, and a spur mark can be hardly generated.

A substantially star-shaped spur and a support member for the spur are provided within a region of the process cartridge which is close to the process cartridge and the conveyance path of the recording medium. By providing the spur rotation support portion corresponding to the rear end passing side on the inside, it is possible to smoothly transfer the recording medium and maintain a good image.

Further, with the copying machine of the above embodiment,
The image forming apparatus is reduced in size due to the proximity of each component in the apparatus,
This can sufficiently contribute to shortening of the recording medium transport path, shortening of output time by shortening the distance between the photosensitive member and the fixing device, and improvement of recording medium productivity.

The present invention is applicable to an electrophotographic printer, an electrophotographic facsimile, an electrophotographic word processor and the like, and is not limited to a copying machine.

Since the copying machine of the present embodiment is provided with the process cartridge that does not stain the recording medium, a high-quality image can be formed on a sheet.

[0074]

According to the process cartridge of the present invention, a plurality of sheet conveying rotating members are arranged on the sheet guiding means side from a line connecting the sheet passing portion of the image carrier and the sheet passing portion of the sheet conveying means. It is possible to prevent the sheet from being soiled even if the sheet does not come into contact with the spur even when the sheet is close to the tangent line, or even if the recording medium jumps up and comes into contact with the spur.

[Brief description of the drawings]

FIG. 1 is a schematic front sectional view of a process cartridge and its periphery when a process cartridge according to an embodiment of the present invention is incorporated in a copying machine.

FIG. 2 is a schematic front sectional view of the process cartridge according to the embodiment of the present invention.

FIG. 3 is a diagram illustrating a state in which a conveyance unit is opened to remove a jammed recording medium (sheet) in FIG.

FIG. 4 is a diagram illustrating a state in which the rear end of the recording medium is instantaneously released from the distortion given to the recording medium by the nip of the fixing device, and is in contact with the lowermost spur.

FIG. 5 is a plan view showing an arrangement state of spurs when there are three spur rows.

FIG. 6 is a diagram illustrating a state in which the rear end of the recording medium is scraping off accumulated toner.

FIG. 7 is a schematic front sectional view of a process cartridge when a process cartridge provided with an auxiliary spur on the upstream side of the spur on the upstream side in the transport direction is incorporated in a copying machine and the periphery thereof.

FIG. 8 is an enlarged view of two spurs on the upstream side and its periphery in FIG.

9 is a state diagram when two spurs on the upstream side have the same diameter in FIG.

FIG. 10 is a state diagram when two spurs on the upstream side are separated from each other in FIG. 9;

FIG. 11 is a diagram showing a rotation support portion of the most upstream spur.

FIG. 12 is a diagram showing a rotation support portion of the most upstream spur.

FIG. 13 is a diagram showing a rotation support portion of a second spur from the upstream side.

FIG. 14 is a plan view showing an arrangement state of spurs when there are four spur rows.

FIG. 15 is a perspective view of a seat.

FIG. 16 is a schematic front cross-sectional view of a process cartridge when the most downstream spur is provided outside the process cartridge, and the periphery thereof.

FIG. 17 is a schematic front sectional view of a copying machine (image forming apparatus) including a process cartridge according to an embodiment of the present invention in an apparatus main body.

FIG. 18 is a schematic front sectional view of a process cartridge and its surroundings when a conventional process cartridge is incorporated in a copying machine.

FIG. 19 is a schematic front cross-sectional view of a conventional process cartridge for guiding a recording medium with a star-shaped spur having a small contact area of a contact portion with the recording medium (sheet) and the periphery thereof.

FIG. 20 is a state diagram when the recording medium contacts the guide ribs between spurs in FIG.

FIG. 21 is a state diagram when the rear end of the recording medium comes into contact with a portion supporting the spur in FIG. 19;

[Explanation of symbols]

P Recording medium (sheet) k Line connecting the sheet passing portion of the photoconductor and the sheet passing portion of the sheet conveying means L Spacing rotation center interval d Valley diameter d1, d2 Spur radius N1 Sheet of photoconductor (image carrier) Passing portion N2 Sheet passing portion of fixing device (sheet guide means) 1 Photoconductor (image carrier) 7 Fixing device (transfer means, sheet guide means) 31 Process cartridge 31a Lower surface of process cartridge (sheet guide means) 40a, 40b, 40c, 40d spur (rotating body for sheet conveyance) 86 transfer unit (transfer unit)

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H071 AA06 AA13 BA04 BA14 BA15 BA23 BA36 DA09 DA10 DA12 DA23 EA04 2H072 CB08 JA04 3F049 CA02 DA05 LA02 LB03

Claims (10)

[Claims] An image carrier capable of carrying an image to be formed on a conveyed sheet, and guides the sheet conveyed to sheet conveyance means disposed downstream of the image carrier in a sheet conveyance direction. And a plurality of sheet conveying rotating members arranged between the image carrier and the sheet conveying unit, the plurality of sheet conveying rotating members having a plurality of corners formed on the outer periphery and arranged in the sheet conveying direction. A process cartridge, wherein the plurality of sheet conveying rotating members are arranged on the sheet guiding unit side from a line connecting a sheet passing portion of the image carrier and a sheet passing portion of the sheet conveying unit. 2. The method according to claim 1, wherein the plurality of sheet transport rotators are such that a sheet transport rotator on the downstream side in the sheet transport direction is closer to the sheet of the image carrier than an upstream sheet transport rotator in the sheet transport direction. The process cartridge according to claim 1, wherein the process cartridge is separated from a line connecting a passing portion and a sheet passing portion of the sheet conveying means. 3. An interval between the plurality of sheet conveying rotators is a distance between the sheet conveying rotators on the downstream side in the sheet conveying direction than an interval between the sheet conveying rotators on the upstream side in the sheet conveying direction. The process cartridge according to claim 1, wherein the process cartridge is wider. 4. An image forming apparatus according to claim 1, wherein, of the plurality of sheet transporting rotators, two pairs of sheet transporting rotators on the upstream side in the sheet transporting direction are connected to a sheet passing portion of the image carrier and a sheet passing portion of the sheet transporting means. And the sheet guide means, and are arranged at different positions in a direction intersecting with the sheet conveying direction, and the rotation center interval between adjacent sheet conveying rotating bodies is set to The process cartridge according to any one of claims 1 to 3, wherein the process cartridge is set to be equal to or less than the sum of the radii of the sheet conveying rotating members. 5. A plurality of sheet transport rotators of the plurality of sheet transport rotators are arranged in a direction intersecting with the sheet transport direction, and the number of sheet transport rotators is greater than the number of the sheet transport rotators arranged upstream in the sheet transport direction. The process cartridge according to any one of claims 1 to 4, wherein the number of arrangements of the sheet conveyance rotating body on the downstream side in the sheet conveyance direction is larger. 6. The sheet transporting rotator located at least on the most upstream side among the plurality of sheet transporting rotators is a spur rotatably supported by a rotary support means, and the spur of the rotary support means is provided. 2. A part downstream from a rotation center is smaller than a valley diameter of the spur.
6. The process cartridge according to any one of Items 5 to 5. 7. The sheet conveying rotating body positioned at the most upstream side is disposed between a line connecting a sheet passing part of the image carrier and a sheet passing part of the sheet conveying means and the sheet guiding means. The process cartridge according to claim 6, wherein the process cartridge is formed. 8. A process cartridge according to claim 1, further comprising: a sheet transport unit that receives and transports a sheet that has passed through the process cartridge. Image forming device. 9. An image of the process cartridge, comprising: the process cartridge according to claim 1; and sheet conveying means for receiving and conveying a sheet that has passed through the process cartridge. An image forming apparatus, wherein a distance between a carrier and the sheet conveying means is set shorter than a length of a minimum size sheet among sheets on which an image is formed by the image carrier. 10. The process cartridge according to claim 1, further comprising: a sheet transport unit that receives and transports a sheet that has passed through the process cartridge. An image forming apparatus for fixing an image transferred by a process cartridge to the sheet.