JP4028953B2 - Image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus such as a copying machine, a facsimile machine, and a printer. More specifically, the present invention accommodates a rotating body used for image formation and at least one of a member and an apparatus used for image formation. The present invention relates to an image forming apparatus having a removable image forming unit.
[0002]
[Prior art]
Conventionally, as an image forming apparatus such as a copying machine, a facsimile machine, and a printer, an image forming unit (consumable parts such as an image carrier, a charging device, a developing device, a cleaning device, a toner storage unit, and a waste toner storage unit) is compactly unitized. A cartridge having a process cartridge is also known. For example, Japanese Patent Laid-Open No. 9-281810 discloses an image forming apparatus in which an image forming unit containing a photosensitive drum as an image carrier, a developing device, a charging device, a cleaning device and the like is detachably mounted. Such an image forming apparatus is excellent in that the maintenance can be simplified because all the consumable parts in the image forming unit can be replaced together simply by replacing the image forming unit.
[0003]
[Problems to be solved by the invention]
By the way, in the image forming apparatus described in the above publication, as a separation mechanism for separating the paper (transfer material) conveyed in contact with the photosensitive drum from the photosensitive drum, the separation mechanism contacts the photosensitive drum at a predetermined pressure. The provided separation claw is used. Since the separation claw is adhesively fixed to a photosensitive housing that is a support housing for the photosensitive drum in the image forming unit, the separation claw is replaced integrally with the unit when the image forming unit is replaced.
[0004]
However, since the image forming unit is replaced when the toner runs out or the waste toner becomes full, for example, when the image forming unit is used under printing conditions with a large amount of toner consumption, before the separation claw reaches the end of its life. There was a problem that it was exchanged, resulting in a waste of cost.
[0005]
The above problems are not limited to the case where the image carrier such as the photosensitive drum and the separation mechanism for separating the transfer material from the image carrier are accommodated in the same image forming unit. Even when the rotating body used for image formation such as a fixing roller for fixing the transfer image on the transfer material and the separation mechanism for separating the transfer material from the rotating body are accommodated in the same image forming unit, It is thought that it occurs similarly.
[0006]
The present invention has been made in view of the above problems, and an object of the present invention is to reduce the cost of replacement of the image forming unit by reducing the components of the image forming unit. Is to provide.
[0007]
[Means for Solving the Problems]
In order to achieve the above-mentioned object, the invention according to claim 1 is an image forming apparatus that accommodates a rotating body used for image formation and at least one of a member and an apparatus used for image formation, and is detachable from the apparatus main body. in the image forming apparatus having the unit, and opening and closing operations with respect to the apparatus main body, opening has a closing cover structure moves away from the rotary member during the operation, the transfer material is in contact with said rotating body However, the opening / closing cover structure in the closed state and the rotating body are configured to be conveyed, and a separation mechanism for separating the transfer material from the rotating body by the sheet-like member is provided in the opening / closing cover. together with the cover structure in operation of opening the structure is provided on the cover structure to move in a direction away from the rotating body, of the cover structure in a state where the transfer material is closed Main unit That is configured to be transported between the facing surfaces and the sheet-like member is characterized in.
In this image forming apparatus, since the separation mechanism is provided on the apparatus main body side, the components of the image forming unit are reduced as compared with the case where the separation mechanism is provided in the image forming unit. The cost for replacement is reduced.
According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the two sheet-like members are provided so that the tip portions thereof are in contact with the rotating body, and the two sheet-like members are formed of a transfer material. The two sheet-like members are rotated about a virtual rotation axis parallel to the transfer material conveyance direction so as to come into contact with the edge on the rotating body side of both ends of the transfer material in a direction orthogonal to the conveyance direction. The two sheet-like members are arranged such that the sheet surfaces of the sheet-like members are inclined at a predetermined angle with respect to the plane parallel to the separated transfer material.
In this image forming apparatus, the two sheet-like members are in contact with the edges on the rotating body side of both ends of the transfer material in the direction orthogonal to the transfer material conveyance direction, so that the sheet-like member and the transfer material are transferred. Line contact at the material edge. Therefore, the two sheet-like members are arranged in parallel to the surface parallel to the separated transfer material, and the sheet-like member is compared with the case where the two sheet-like members and the transfer material are in surface contact with each other. And the contact area between the transfer material and the transfer material can be reduced. Therefore, the chance that the transfer image on the transfer material is rubbed with the sheet-like member is reduced, and occurrence of image rub is suppressed.
According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect, the sheet-like member is provided so that a tip portion thereof is in contact with the rotating body, and the transfer material is carried on the transfer material by the sheet-like member. The shape of the sheet-like member is set so that the transfer material is guided in such a direction that the surface is not in contact with the member arranged in the vicinity of the separation mechanism.
In this image forming apparatus, the sheet-like member guides the transfer material in such a direction that the transfer image carrying surface of the transfer material is not in contact with the member. Is avoided, and image blurring due to the contact is prevented.
According to a fourth aspect of the present invention, in the image forming apparatus according to the first, second, or third aspect, the sheet-like member is a member having at least a contact portion with the rotating body having elasticity.
In this image forming apparatus, since at least a contact portion of the sheet-like member with the rotating body has elasticity, damage to the surface of the rotating body due to contact with the sheet-like member is prevented.
[0015]
A latent image writing unit 6 for writing an electrostatic latent image on the photoreceptor 1 is provided on the side of the image forming unit 100. As this latent image writing unit 6, for example, an optical signal corresponding to image information read by a scanner or the like is emitted from a semiconductor laser, and the laser beam is scanned by a polygon mirror that is driven to rotate. A device for writing an optical signal 6a corresponding to color-separated image information on a photosensitive member through a converging lens and a mirror for correcting surface tilt of a polygon mirror disposed in the optical path, a mirror for deflecting laser light, or the like is used. be able to.
[0016]
Also, below the image forming unit 100, a transfer roller 8 for separating and feeding transfer sheets 8 as transfer materials stored in a sheet feed cassette 7 one by one, and a sheet feed roller 9 feeds the sheet. After the transferred transfer paper 8 is temporarily kept in front of the photoreceptor 1, the leading edge of the image formed on the photosensitive body 1 and the leading edge of the transfer paper 8 serve as the photosensitive body 1 and a transfer unit. A registration roller 11 is provided for re-feeding the transfer paper 8 in synchronism with the rotation of the photoconductor 1 at the timing when the nip portion with the transfer roller 10 is reached almost simultaneously.
[0017]
Further, above the image forming unit 100, there are a fixing roller 14 and a press roller 15 containing a heater 13 rotatably arranged so as to be pressed against each other across the conveyance path 12 of the transfer paper 8. A fixing device 16 is provided. In addition, on the downstream side of the fixing device 16 in the transfer paper conveyance direction, the transfer paper 8 that has passed through the nip between the fixing roller 14 and the press roller 15 is discharged on the upper side of the main body case 200 a of the printer 200. A paper discharge roller 18 for discharging the paper to the stacker unit 17 is provided.
[0018]
Also, in the main body case 200a of the printer 200, an electrical unit 20 is provided as a control means for controlling each image forming means and print information related to the image forming process of the printer 200. The electrical unit 20 includes a control board (not shown) and various adjustment switches and control units mounted on the control board, and is arranged from the side to the lower side of the latent image writing unit 6. It is housed in an electrical case 21 made of metal.
[0019]
In the printer 200 having such a configuration, first, the photosensitive member 1 is uniformly charged by the charge from the charging roller 2 during rotation. Next, the latent image writing unit 6 is driven based on image information read from the outside, whereby the image information is formed as an electrostatic latent image in the charging area (image forming area) of the photoreceptor 1. The The electrostatic latent image formed on the photosensitive member 1 is developed with a developer (toner) supplied to the photosensitive member 1 by the developing roller 3a of the developing unit 3 to become a visible image (toner image).
[0020]
On the other hand, while the toner image is being formed on the photosensitive member 1, the transfer paper 8 is pulled out from the paper supply cassette 7 by the paper supply roller 9, and the leading end of the transfer paper 8 is in the nip of the registration roller 11. The transfer paper 8 is put on standby in a state where it is in contact with the portion. The transfer paper 8 starts rotating with the registration roller 11 in synchronization with the rotation of the photosensitive member 1 at the timing when the leading end of the transfer paper 8 and the leading end of the toner image coincide with each other. The photosensitive member 1 is conveyed to a transfer position formed at a nip with a transfer roller 10 that is pressed against and rotated. As a result, the transfer paper 8 on which the toner image on the photosensitive member 1 is transferred at the transfer position is fixed in the process of being conveyed by the fixing roller 14 and the press roller 15 of the fixing device 16 and discharged. The paper is discharged onto the stacker unit 17 by the roller 18. In the meantime, the residual toner remaining on the photosensitive member 1 without being transferred onto the transfer paper 8 in the transfer process of the toner image onto the transfer paper 8 is transferred to the photosensitive member 1 by the cleaning blade 4a of the cleaning unit 4. It is removed from above and collected in the cleaning container 4b.
[0021]
Further, the charge on the transfer paper 8 is removed by a static elimination brush 22 as a static elimination means disposed on the downstream side of the transfer roller 10 in the transfer paper conveyance direction.
Further, the printer 200 according to the present embodiment is provided with a separation claw 203 that separates the transfer paper 8 conveyed in contact with the photosensitive member 1 from the photosensitive member, and the transfer paper 8 that has been discharged by the discharging brush 22 is removed. It is physically separated from the photoreceptor 1. The separation mechanism using the separation claw 203 will be described in detail later.
[0022]
On the other hand, the main body case 200a of the printer 200 includes an open / close cover structure 201 that forms a side surface of the main body case 200a on the transfer path 8 side of the transfer paper 8 and a manual feed unit 23 for manually feeding the transfer paper. Are supported by the same support shaft 202. This manual feed unit 23 is configured to be able to take the open position shown in FIG. 1 and the closed position (see FIG. 2) stored in the manual feed unit storage portion 201c which is a recess of the opening / closing cover structure 201. ing. The transfer paper fed using the manual feed unit 23 is conveyed to the registration roller 11 by the rotation of the manual paper feed roller 24 provided on the printer main body 200 side.
[0023]
Further, as shown in FIG. 3, a holder portion 201 b that holds the transfer roller 10 is fixed to the opening / closing cover structure 201, so that the transfer roller 10 is supported by the opening / closing cover structure 201. . Further, the static elimination brush 22 is also attached to the opening / closing cover structure 201.
[0024]
Further, a conveyance guide plate 201a for forming the transfer paper conveyance surface of the conveyance path 12 and guiding the transfer paper 8 to the fixing device 16 is guided to the opening / closing cover structure 201 by the end surface thereof. Thus, a plurality of sheets are arranged along the longitudinal direction of the photosensitive member 1 (see FIG. 7). In this embodiment, the conveyance guide rib 201a is formed as an integral part with the opening / closing cover structure 201 to reduce the number of components of the printer, but it is formed as a separate member and attached to the opening / closing cover structure 201. Also good. For example, if the conveyance guide plate 201a is formed using a conductive member having a medium resistance, toner dust in an unfixed image is suppressed and a higher quality image can be obtained.
[0025]
In FIG. 1, when the opening / closing cover structure 201 is opened in the clockwise direction in the drawing with the support shaft 202 as the center of rotation, as shown in FIG. 2, the conveyance guide plate 201a, the transfer roller 10, and the charge eliminating brush 22 are shown. However, the transfer paper 8 is largely retracted from the conveyance path 12. Therefore, operations such as attachment / detachment of the image forming unit 100 to / from the printer body, replacement of the fixing device 16, and jam processing of the transfer paper 8 jammed in the transport path 12 can be easily performed.
[0026]
Next, a separation mechanism that separates the transfer paper 8 from the photoreceptor 1, which is a characteristic part of the present embodiment, will be described with reference to FIGS. 3 and 4.
FIG. 3 is a cross-sectional view illustrating a schematic configuration of the separation mechanism, and FIG. 4 is a perspective view of the separation mechanism. The separation mechanism is configured using the separation claw 203 made of a sheet-like member and a support member 202 that supports the separation claw 203. The tip of the separation claw 203 is processed at an acute angle as shown. Further, the separation claw 201 is supported by the support member 203 so that the tip portion thereof can come into contact with the surface of the photoreceptor 1. The separation claw 203 and the support member 202 are provided on the two conveyance guide plates 201a at both ends in the longitudinal direction of the photosensitive member 1 in the conveyance guide plate 201a (see FIG. 7). In this embodiment, the support member 202 is attached to the conveyance guide plate 201a with a double-sided tape.
[0027]
The material of the separation claw 203 is preferably such that at least the contact portion with the photoconductor is elastic so that the surface of the photoconductor 1 is not damaged by contact with the separation claw 201. In this embodiment, a sheet-like member made of a PET (polyethylene terephthalate) film having a thickness of 0.125 mm is used as the separation claw 203. Further, as the support member 202, a SUS material having a thickness of 1 mm is used.
[0028]
As described above, in the printer 200 according to this embodiment, the separation mechanism that separates the transfer paper 8 conveyed in contact with the photosensitive member 1 is used as the opening / closing cover on the printer 200 main body side via the conveyance guide plate 201a. Since the structure 201 is provided, the components of the image forming unit 100 can be reduced and the cost for replacement of the image forming unit 100 can be reduced as compared with the case where the separation mechanism is provided in the image forming unit 100. Can do.
[0029]
Further, the separation claw 203 guides the transfer paper 8 in such a direction that the transfer image carrying surface of the transfer paper 8 is not in contact with the housing 4c of the cleaning unit 4 disposed in the vicinity of the separation claw 203. The shape is set. Specifically, as shown in FIG. 4, the separation claw 203 is bent in a direction away from the housing 4 c of the cleaning unit 4.
The operation and effect of the printer 200 of the present embodiment having the separation claw 203 set in such a shape will be described below in comparison with a comparative example.
[0030]
FIG. 5 is an explanatory diagram illustrating the traveling direction of the transfer paper 8 of the printer 200 according to the present embodiment. FIG. 6 is an explanatory diagram illustrating the traveling direction of the transfer paper 8 of the printer 200 according to the comparative example. . In the comparative example shown in FIG. 6, the separation claw 203 does not have a bent portion, and the tip portion is in contact with the photoreceptor 1 while maintaining a linear shape.
In the configuration of the comparative example in FIG. 6, the transfer paper 8 that has passed the transfer position is conveyed in a state of being electrostatically attracted to the photoreceptor 1 and physically separated by the separation claw 203. Then, the separated transfer paper 8 advances in the direction of the arrow in the figure. Therefore, the toner image carrying surface of the transfer paper 8 may come into contact with the housing 4c of the cleaning unit 4 and the toner image may be rubbed.
[0031]
On the other hand, in the configuration of the present embodiment in FIG. 5, the transfer paper 8 that has been physically separated by the separation claw 203 is guided by the bent portion of the separation claw 203 toward the conveyance guide plate 201 a, and Proceed in the direction of the middle arrow. Therefore, the separation claw 203 can guide the transfer material in such a direction that the toner image carrying surface of the transfer paper 203 is not in contact with the housing 4 c of the cleaning unit 4, and the housing 4 c and the transfer paper 8 can be guided. The contact with the toner image carrying surface can be avoided. As a result, the unfixed toner image is not rubbed, and generation of a rubbed image due to the contact can be prevented.
[0032]
Further, in the present embodiment, the two separation claws 203 are in contact with the edges on the side of the photoreceptor 1 on both ends of the transfer paper in the direction orthogonal to the transfer paper conveyance direction. Are inclined at a predetermined angle with respect to the plane parallel to the transfer paper 8 after separation. Specifically, as shown in FIGS. 7 and 8, after the separation, the support members 202 that support the separation claws 203 are transferred so that the two separation claws 203 are in contact with the edge 8 a of the transfer paper 8. An angle α is provided with respect to a plane parallel to the paper 8. In the illustrated example, α = 18 degrees is set. In such a configuration, the separation claw 203 and the transfer paper 8 are in line contact at the edge 8 a of the transfer paper 8. Therefore, for example, like the separation claw 203 ′ indicated by a virtual line (two-dot broken line) in FIG. 8, the separation claw 203 ′ and the transfer paper 8 are arranged in parallel to the plane parallel to the transfer paper 8 after separation. The contact area between the separation claw 203 and the transfer paper 8 can be reduced as compared with the case where the surface contact is made. Therefore, the chance that the toner image on the transfer paper 8 is rubbed by the separation claw 203 can be reduced, and the occurrence of image rub can be suppressed. Note that the value of the angle α may be set as appropriate within a range in which the transfer paper 8 can be satisfactorily separated while suppressing the occurrence of image blurring.
[0033]
【The invention's effect】
According to the first aspect of the invention, it is possible to reduce the cost of replacement of the image forming unit by reducing the components of the image forming unit.
Further, according to the second aspect of the present invention, it is possible to reduce the chance that the transfer image on the transfer material is rubbed by the sheet-like member and to suppress the occurrence of image rub.
According to the invention of claim 3 , it is possible to avoid contact between a member or device arranged in the vicinity of the separation mechanism and the transfer image carrying surface of the transfer material, and to prevent occurrence of image rubbing due to the contact. There is an effect that can be done.
According to the invention of claim 4 , there is an effect that damage to the surface of the rotating body due to contact with the sheet-like member can be prevented.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram illustrating an entire printer according to an embodiment.
FIG. 2 is a schematic configuration diagram illustrating a state where an opening / closing cover of the printer is opened.
FIG. 3 is a cross-sectional view showing a schematic configuration of a separation mechanism.
FIG. 4 is a perspective view of the separation mechanism.
FIG. 5 is an explanatory diagram for explaining a traveling direction of transfer paper of the printer according to the embodiment.
FIG. 6 is an explanatory diagram for explaining a traveling direction of a transfer sheet of a printer according to a comparative example.
FIG. 7 is a side view of the separation mechanism and the conveyance guide plate viewed from the transfer material conveyance direction.
FIG. 8 is an explanatory diagram for explaining the arrangement of separation claws constituting the separation mechanism.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Charging roller 3 Developing unit 4 Cleaning unit 8 Transfer paper 10 Transfer roller 12 Transfer paper transport path 14 Fixing roller 15 Press roller 16 Fixing device 22 Static elimination brush 100 Process cartridge 200 Printer 200a Printer main body case 201 Opening / closing cover 201a Transport Guide plate 202 Support member 203 Separation claw (sheet-like member)

Claims (4)

In an image forming apparatus having a rotating body used for image formation and at least one of a member and an apparatus used for image formation and having an image forming unit detachable from the apparatus main body,
An opening / closing cover structure that opens and closes with respect to the apparatus body and moves in a direction away from the rotating body during the opening operation,
The transfer material is configured to be conveyed between the opening / closing cover structure and the rotating body in a closed state while being in contact with the rotating body ,
Separating mechanism for separating from the rotating member transfer material by the sheet-like member, the cover structure as with the cover structure upon the opening operation of the closing cover structure moves away from the rotary member It is provided to the body,
An image forming apparatus, wherein the image forming apparatus is configured to be conveyed between a surface facing the apparatus main body of the opening / closing cover structure in a state where a transfer material is closed and the sheet-like member. The image forming apparatus according to claim 1.
Two of the sheet-like members are provided so that the tip portions thereof are in contact with the rotator, and the two sheet-like members are on the rotator side of both end faces of the transfer material in a direction orthogonal to the transfer material conveyance direction. The two sheet-like members are rotated around a virtual rotation axis parallel to the transfer material conveyance direction so that the sheet surfaces of the two sheet-like members are parallel to the transfer material after separation. An image forming apparatus, wherein the two sheet-like members are arranged so as to be inclined at a predetermined angle with respect to a smooth surface. The image forming apparatus according to claim 1 or 2,
The sheet-like member is provided so that the tip thereof is in contact with the rotating body, and the transfer image carrying surface of the transfer material is not in contact with the member arranged in the vicinity of the separation mechanism by the sheet-like member. An image forming apparatus, wherein the shape of the sheet-like member is set so as to guide the transfer material in the direction. The image forming apparatus according to claim 1, 2 or 3.
The image forming apparatus, wherein the sheet-like member is a member having elasticity at least in contact with the rotating body.

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