JP2004004344A - Image carrying device of image forming device and the image forming device with the image carrying device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image carrying device of an image forming device which can surely separate a sheet material from an image transfer belt after a toner image is transferred from the image transfer belt to the sheet material. <P>SOLUTION: An image carrying belt 21 has a no-image formation area 69 where no toner image is carried and a sheet separation part 71 is formed on the outer circumferential surface of the no-image formation area 69. The image carrying belt 21 and a sheet member S are driven in timing to the superposition of a margin part of the sheet member on the front end side in a transport direction on the sheet separation part 71. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image bearing device used to temporarily hold a toner image in an electrophotographic image forming apparatus such as a laser printer, a copying machine, and a facsimile. The present invention relates to a structure for avoiding a state in which a sheet member adheres to an image carrying belt after a toner image is transferred.
[0002]
[Prior art]
In the image forming apparatus, several methods have conventionally been proposed as a method for separating the sheet member after the image transfer from the belt carrying the toner. For example, in Japanese Patent Application Laid-Open No. 7-36288, as shown in FIG. 8, a flexible photosensitive belt 103 which rotates in accordance with the rotation of a driving roller 101, and a driving roller which allows the belt 103 to rotate. An image forming apparatus is disclosed that includes a developing roller 107 and a cleaning blade 109 that form a projecting slack portion 105 having a radius of curvature R2 smaller than the curvature radius R1 of 101, and a transfer device 111 that faces the projecting slack portion 105. .
[0003]
In such an image forming apparatus, when the transfer sheet material is separated from the photoreceptor after the transfer of the toner image, the curvature can be separated without the separation claw, but the transfer efficiency is reduced due to the small curvature of the transfer portion. . In particular, when a roller is used in the transfer device, the transfer efficiency is significantly reduced, and image defects are likely to occur. Further, when the apparatus is stopped, permanent distortion may occur in a small curvature portion, and an image cannot be formed well in the developing portion in such a permanent distortion portion, or in the transfer portion. Transfer cannot be performed. Furthermore, in such an image forming apparatus, since the photoreceptor belt 103 is bent with a small curvature over the entire circumference, there is a possibility that the damage to the belt is large and the belt is broken or the like.
[0004]
Japanese Patent Application Laid-Open No. Hei 9-15987 discloses that, as shown in FIG. 9, at the position where the transfer material P is separated from the transfer belt 121 that conveys the transfer material P, the surface of a roller 123 that supports the transfer belt 121 from the back surface. It is disclosed that a projection 125 is formed, and an air gap is formed between the transfer belt 121 and the transfer material P by the projection 125 to surely separate the transfer material P from the transfer belt 121.
[0005]
However, when applying such a transport belt technology to an image bearing belt, permanent deformation occurs remarkably on the surface of the belt, particularly when the apparatus is stopped, so that an image can be surely formed. become unable. Further, in the case of the image carrying belt, it is necessary to clean the toner remaining after the image is transferred onto the transfer material, and even a slight distortion of the image carrying belt causes a cleaning failure, resulting in image contamination.
[0006]
[Problems to be solved by the invention]
An object of the present invention is to provide an image forming apparatus in an image forming apparatus capable of reliably separating a sheet member from an image carrying belt after transferring a toner image from the image carrying belt to a sheet member, and an image including the image carrying apparatus. An object of the present invention is to provide a forming apparatus.
[0007]
In Japanese Patent Application Laid-Open No. Hei 10-221967, detection is performed by forming a reinforcing guide on the inner peripheral surface of the image carrying belt except for a joint portion serving as a seam at the end of the belt, and providing a reference mark on the image carrying belt. Accordingly, it is disclosed that control is performed such that an image is formed in a region other than the joint. However, an object of the invention according to the prior art is to guide the reinforcing guide by a guide groove or the like provided at an end of a support roller so that the belt can be prevented from coming off and can be driven stably. Neither the above-mentioned problems of the invention nor the specific means for solving the problems described below are disclosed at all, and there is no description suggesting the same.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the image bearing device in the image forming apparatus according to the first aspect of the present invention can be driven along at least two rollers and a belt driving path formed around the rollers. An endless image bearing belt having a surface capable of bearing a toner image, the image bearing belt being disposed so as to be in contact with the peripheral surface of the photosensitive drum, and the toner image carried on the image carrying belt. And a transfer roller provided as one of the rollers for transferring the sheet member to be transferred, and arranged so as to form a conveyance path of the sheet member between the transfer roller and the transfer roller. The image carrying belt has a non-image forming area that does not carry a toner image, and a sheet separating portion is formed on all or a part of the outer peripheral surface of the non-image forming area. The image carrying belt is driven and the sheet member is driven between the transfer roller and the pressing roller at a timing when a margin (margin) portion of the front end side of the sheet member in the conveying direction overlaps with the sheet separating portion. Is transported.
[0009]
According to the present invention, a non-image forming area that does not carry a toner image is formed on the image carrying belt, and the sheet separating portion formed in the non-image forming area overlaps a margin portion on the front end side in the transport direction of the sheet member. The image carrying belt is driven at a timing and the sheet member is conveyed. As a result, the front end of the sheet member always comes into contact with the sheet separating portion having low adhesion, and after the front end of the sheet member has passed through the transfer roller, the front end of the sheet member is restored due to the restoration tendency of the sheet member. Separated from the separation unit.
[0010]
Further, by forming the sheet separating section only in the non-image forming area, a large curvature can be realized in other image forming areas, and the transfer efficiency can be increased as compared with the related art. Further, since permanent distortion is generated only in the non-image forming area, image defects are eliminated, and dirt due to defective cleaning does not reach the image forming area.
[0011]
Also, in the image bearing device in the image forming apparatus according to the second aspect of the present invention, in the first aspect, the sheet separating portion is formed by a plurality of irregularities extending in a direction orthogonal to a driving direction of the image bearing belt. It is characterized by having been done.
[0012]
According to the present invention, since the contact area between the sheet separating portion and the sheet member is reduced due to the presence of the plurality of irregularities, the sheet member is easily separated from the sheet separating portion.
[0013]
Also, in the image bearing device in the image forming apparatus according to the invention described in claim 3 of the present invention, in the image bearing device according to claim 1, the sheet separating portion is formed by a single groove extending in a direction orthogonal to a driving direction of the image bearing belt. It is characterized by being formed. According to the present invention, since the single groove is not in contact with the sheet member, the sheet member starts to be peeled from the image carrying belt from the non-contact portion.
[0014]
In the image forming apparatus according to the fourth aspect of the present invention, in the image forming apparatus according to the first aspect, the sheet separating unit may include a single ridge extending in a direction orthogonal to a driving direction of the image supporting belt. Characterized by being formed by: According to the present invention, since the contact area between the single ridge and the sheet member becomes linear, the sheet member starts to peel from the image carrying belt from this portion.
[0015]
According to a fifth aspect of the present invention, in the image forming apparatus according to the first aspect of the present invention, the image bearing belt is configured such that one belt-shaped belt member is formed in a ring shape. The sheet separating portion is formed by connecting the both ends, and the sheet separating portion is formed around the connecting portion at the both ends. Since the periphery of the connection portion is originally unsuitable as an image forming area, this portion can be meaningfully used as a sheet separation portion.
[0016]
Further, in the image bearing device in the image forming apparatus according to the invention described in claim 6 of the present application, in the image bearing device according to claim 2 or 4, the convex portion or the ridge of the sheet separating portion is provided on an inner surface side of the image carrying belt. It is characterized by being formed by the presence of the provided auxiliary member.
According to the present invention, it is possible to easily form the sheet separating portion only by interposing the auxiliary member while keeping the surface shape of the image carrying belt.
[0017]
According to the image bearing device of the image forming apparatus according to the present invention, in the image forming apparatus according to the fifth aspect, the convex portion, the convex ridge, the concave portion, or the groove of the sheet separating portion may be the connecting portion. In which the material connecting the both ends is formed on the material itself.
According to the present invention, a material for connecting both ends is formed in advance with a convex portion or a ridge or a concave portion or a groove, and the sheet separating portion can be easily formed simply by connecting both ends of the image carrying belt through this. Can be formed.
[0018]
An image forming apparatus according to an eighth aspect of the present invention includes the image bearing device according to any one of the first to seventh aspects. According to the image forming apparatus of the present invention, since the sheet member can be easily separated from the image carrying belt and can proceed linearly, it is possible to prevent jamming of the sheet member and perform efficient image formation. Can be.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a side sectional view showing a rotary type image forming apparatus 1 provided with an image bearing device according to the present invention. In the image forming apparatus 1, a photosensitive drum 5 is provided in the apparatus main body 3 so as to be rotatable in a direction of an arrow 7. Around the photoreceptor drum 5, along a rotation direction 7, a charger 9 as a charging unit, a rotary developing unit 11 for holding a developing cartridge as a developing unit, and a cleaning unit 13 are arranged. The charger 9 is applied with a charging bias from a charging bias circuit (not shown), and can uniformly charge the peripheral surface of the photosensitive drum 5.
[0020]
An exposure unit 15 is provided below the rotary developing unit 11, and the exposure unit 15 emits a laser beam L toward the outer peripheral surface of the photosensitive drum 5 charged by the charger 9. The exposure unit 15 scans and exposes the laser beam L onto the photosensitive drum 5 in accordance with image data obtained by developing the image forming command into an image, and forms an electrostatic image corresponding to the image forming command on the photosensitive drum 5. Form a latent image.
[0021]
The electrostatic latent image thus formed is developed by the rotary developing unit 11 with toner. That is, in the present embodiment, as the rotary developing unit 11, a yellow developing cartridge 12 </ b> Y, a cyan developing cartridge 12 </ b> C, a magenta developing cartridge 12 </ b> M, and a black developing cartridge 12 </ b> K 31 is provided rotatably. These developing cartridges 12Y, 12C, 12M, and 12K (hereinafter collectively referred to as developing cartridges 12) all have the same configuration, and contain toner as shown in FIG. A supply roller 53 and a developing roller 55 are provided for the housing 43.
[0022]
When the position of the developing unit 11 in the circumferential direction is determined, the developing roller 55 of the developing cartridge 12 is selectively adjacent to the photosensitive drum 5 to supply toner to the surface of the photosensitive drum 5. it can. Thus, the electrostatic latent image on the photosensitive drum 5 is visualized with the selected toner color. FIG. 1 shows a state where the developing cartridge 12 </ b> Y for yellow supplies toner to the photosensitive drum 5.
[0023]
A transfer unit 19 is provided above the rotary developing unit 11 and the cleaning unit 13. The transfer unit 19 includes an endless image carrying belt 21 stretched over a plurality of rollers, and a driving unit (not shown) for driving the image carrying belt 21 to rotate. The toner image developed by the developing unit 11 is primarily transferred onto the image carrying belt 21 of the transfer unit 19 in the primary transfer area 17. The photosensitive drum 5 remains on the outer peripheral surface of the photosensitive drum 5 after the primary transfer by the cleaning unit 13 at a position rotated from the primary transfer area 17 in the rotation direction indicated by the arrow 7 in FIG. The toner is scraped off.
[0024]
When the color image is transferred to the sheet member S, the toner image of each color formed on the photosensitive drum 5 is superimposed on the image carrying belt 21 to form a color image, and in the secondary transfer area 23, The color image is secondarily transferred onto the sheet member S taken out of the cassette 25. The sheet member S on which the color image has been formed in this manner is conveyed via the fixing unit 27 onto the discharge tray section 29 provided on the upper surface of the apparatus main body 3.
[0025]
FIG. 3 is an enlarged view showing the periphery of the image carrying belt 21 and the secondary transfer area 23. The image carrying belt 21 is driven to rotate by a driving source (not shown), and is wound around a driving transfer roller 57 functioning as a transfer roller, a driven roller 59, and a tension roller 61 provided between the two rollers. 3 can be driven in the direction of arrow X. Further, a cleaning unit 63 is provided so as to contact the surface of the image bearing belt 21 in an area adjacent to the driven roller 59, and a pressure roller 65 is provided on the drive transfer roller 57 side.
[0026]
The nipping roller 65 has a function of transporting the sheet member S upward while sandwiching the sheet member S with the driving transfer roller 57 in order to transfer the toner image primarily transferred to the image carrying belt 21 to the sheet member S.
[0027]
As shown in FIG. 4A, the image carrying belt 21 controls the image forming area 67 on the photosensitive drum 5 where the toner image can be received, and controls the image bearing belt 21 not to receive the toner image on the photosensitive drum 5. A non-image forming area 69 is formed, and a sheet separating unit 71 is formed on the outer peripheral surface of the non-image forming area 69. As shown in FIG. 4A, the sheet separating unit 71 can be formed by a plurality of irregularities 73 extending in a direction orthogonal to the driving direction of the image carrying belt 21. In a portion where such a plurality of irregularities 73 are in contact with the sheet member S, the contact area between the image carrying belt 21 and the sheet member S is reduced, so that the sheet member S is easily separated from the image carrying belt 21.
[0028]
The sheet separating section 71 provided on the image carrying belt 21 is detected by a sensor 75 (see FIG. 3), and the front end in the traveling direction of the sheet member S approaching the secondary transfer area 23 is detected by another sensor 77. Have been. The sensors 75 and 77 are connected to a control device 79, and the control device 79 is configured to be able to control the driving of the driving transfer roller 57 and the feeding driving of the sheet member S. When the sensor 77 detects the front end of the sheet member S, the control device 79 stops the feed driving of the sheet member S until the sensor 75 detects the sheet separating unit 71, and then the sensor 75 causes the sheet separating unit 71 to stop. 4B, the control device 79 sets the sheet between the driving transfer roller 57 and the pressing roller 65 at the timing when the margin at the front end of the sheet member S overlaps the sheet separating unit 71, as shown in FIG. The member S is fed and driven.
[0029]
When the sheet member S passes through the secondary transfer area 23 in this manner, the margin of the front end of the sheet member S always overlaps with the sheet separating portion 71. It is possible to avoid being conveyed while being in close contact with the belt 21.
[0030]
In the above-described embodiment, the feed driving of the sheet member S is temporarily stopped immediately before the secondary transfer area 23 to adjust the timing with the sheet separating unit 71. The timing of feeding the sheet member S from the cassette 25 may be adjusted in accordance with the timing, or the timing of driving the image carrying belt 21 may be increased or decreased according to the transport position of the sheet member S. May be matched.
[0031]
Next, various embodiments of the sheet separating unit 71 will be described with reference to FIGS. In the embodiment shown in FIG. 5, the sheet separating section 71 is formed by a single groove 81 extending in a direction orthogonal to the driving direction of the image carrying belt 21. Such a groove 81 is formed in a connecting portion 83 formed between both ends connected when the long belt-shaped image carrying belt 21 is formed in an annular shape. Of course, such a groove 81 may be formed on the outer peripheral surface of the image carrying belt 21 itself.
[0032]
In the embodiment shown in FIG. 6, the sheet separating unit 71 is formed by a single ridge 85 extending in a direction orthogonal to the driving direction of the image carrying belt 21. As shown in FIG. 6A, such a ridge 85 is formed by fixing a thick auxiliary member 87 on the inner surface side of the image carrying belt 21 and by the presence of the auxiliary member 87. I have. Of course, such a ridge 85 may be integrally formed at the stage of forming the image carrying belt 21.
[0033]
Further, in the embodiment shown in FIG. 7, the sheet separating portion 71 is formed by a single ridge 85 extending in a direction orthogonal to the driving direction of the image carrying belt 21, and the ridge 85 has a belt-like shape. It is formed on a connecting portion 83 formed between both ends connected when the image carrying belt 21 is formed in a ring shape. Such a ridge 85 may be formed by, for example, swelling the adhesive used as the connection portion 83, or formed when the both ends of the belt are overlapped and fixed by a method such as sewing. The swelling of the overlapping portion may be used.
[0034]
Although not shown, in connection with the embodiment shown in FIG. 7, a plurality of unevenness 73 as shown in FIG. A groove 81 as shown in FIG. 5 can also be formed.
[0035]
Although the application example of the image bearing device in the image forming apparatus of the present invention in the rotary type image forming apparatus 1 has been described, not only the rotary type, but also the development of the photoconductor of each color in a state where a plurality of developing devices are fixed. The above-described image bearing device can be similarly applied to a so-called tandem-type image forming apparatus and other types of image forming apparatuses. The image forming apparatus according to the present invention includes all apparatuses that form an image by an electrophotographic method, such as a laser printer, a copying machine, and a facsimile.
[0036]
【The invention's effect】
According to the present invention, a non-image forming area that does not carry a toner image is formed on the image carrying belt, and the sheet separating portion formed in the non-image forming area overlaps a margin portion on the front end side in the transport direction of the sheet member. The image carrying belt is driven at a timing and the sheet member is conveyed. As a result, the front end of the sheet member always comes into contact with the sheet separating portion having low adhesion, and after the front end of the sheet member has passed through the transfer roller, the front end of the sheet member is restored due to the restoration tendency of the sheet member. Separated from the separation unit.
[0037]
Further, by forming the sheet separating section only in the non-image forming area, a large curvature can be realized in other image forming areas, and the transfer efficiency can be increased as compared with the related art. Further, since permanent distortion is generated only in the non-image forming area, image defects are eliminated, and dirt due to defective cleaning does not reach the image forming area.
[Brief description of the drawings]
FIG. 1 is a side sectional view showing an image forming apparatus including an image bearing device according to the present invention.
FIG. 2 is a perspective view of a rotary developing unit according to the present invention.
FIG. 3 is an enlarged view showing the periphery of an image carrying belt and a secondary transfer area according to the present invention.
FIGS. 4A and 4B are perspective views showing an embodiment in which a sheet separating portion composed of a plurality of irregularities is formed in a non-image forming area, and FIG. 4B shows a sheet separating operation state; It is a side sectional view.
FIG. 5A is a perspective view showing an embodiment in which a sheet separating portion composed of a single groove is formed in a non-image forming area according to the present invention, and FIG. FIG.
FIG. 6A is a perspective view showing an embodiment in which a sheet separating portion formed of a single convex streak is formed in a non-image forming area according to the present invention, and FIG. FIG.
FIG. 7A is a non-image forming area according to the present invention, in which a single ridge is formed at a connecting portion formed between both ends connected when an image carrying belt is formed in an annular shape; FIG. 2 is a perspective view showing an embodiment in which a sheet separating portion is formed, and FIG. 2 (b) is a side sectional view showing the sheet separating operation state.
FIG. 8 is a schematic diagram showing a conventional method for separating a sheet material after image transfer from a belt carrying toner.
FIG. 9 is a schematic view showing another conventional method for separating a sheet material after image transfer from a belt carrying toner.
[Explanation of symbols]
1 Image Forming Apparatus 5 Photoconductor Drum 11 Rotary Developing Unit 12 Developing Cartridge 13 Cleaning Unit 17 Primary Transfer Area 19 Transfer Unit 21 Image Carrying Belt 23 Secondary Transfer Area 31 Rotary Axis 57 Drive Transfer Roller 59 Follower Roller 63 Cleaning Means 65 Roller 67 Image forming area 69 Non-image forming area 71 Sheet separating section 73 Plural irregularities 75, 77 Sensor 79 Control device 81 Single groove 83 Connecting section 85 Single ridge 87 Auxiliary member S Sheet member

Claims (8)

At least two rollers, and an endless drivable along a belt driving path formed around the rollers, arranged so as to be in contact with the peripheral surface of the photosensitive drum, and having a surface capable of carrying a toner image. An image bearing device comprising an image bearing belt,
A transfer roller provided as one of the rollers for transferring a toner image carried on the image carrying belt to a sheet member to be transferred; and a sheet disposed between the transfer roller and the transfer roller. And a squeezing roller arranged to form a conveying path of the member,
The image carrying belt has a non-image forming area that does not carry a toner image, and a sheet separating unit is formed on all or a part of the outer peripheral surface of the non-image forming area,
The image carrying belt is driven and the sheet member is conveyed between the transfer roller and the pressure roller at a timing when a margin portion on the front end side in the conveying direction of the sheet member overlaps with the sheet separating portion. An image bearing device in an image forming apparatus, wherein: 2. The image forming apparatus according to claim 1, wherein the sheet separating unit is formed by a plurality of irregularities extending in a direction orthogonal to a driving direction of the image carrying belt. 2. The image bearing device according to claim 1, wherein the sheet separating unit is formed by a single groove extending in a direction orthogonal to a driving direction of the image bearing belt. 2. The image bearing device according to claim 1, wherein the sheet separating unit is formed by a single ridge extending in a direction perpendicular to a driving direction of the image bearing belt. 5. The image bearing belt according to claim 1, wherein the image carrying belt is formed by forming one belt-shaped belt member in a ring shape and connecting both ends thereof, and the sheet separating unit includes: An image bearing device in an image forming apparatus, wherein the image bearing device is formed around a connection portion at both ends. 5. The image forming apparatus according to claim 2, wherein the projecting portion or the projecting portion of the sheet separating unit is formed by the presence of an auxiliary member provided on an inner surface side of the image carrying belt. 6. Carrying device. 6. The image forming apparatus according to claim 5, wherein the convex portion, the convex ridge, the concave portion, or the groove of the sheet separating portion is formed in a material itself connecting the both ends in the connecting portion. Image bearing device in the device. An image forming apparatus comprising the image bearing device according to any one of claims 1 to 7.

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