Patent Application
20150030351
This application is based on and claims the benefit of priority from Japanese Patent application No. 2013-156911 filed on Jul. 29, 2013, the entire contents of which are incorporated herein by reference.
The present disclosure relates to a static eliminating device eliminating a static charge remained on a surface of a photosensitive drum and an image forming apparatus including this static eliminating device.
In an electrographic image forming apparatus, in order to reduce a transfer memory image occurred by a static charge remained on a surface of a photosensitive drum after a toner (a developer) is transferred, a static eliminating device irradiates the surface of the photosensitive drum with a static elimination light after the toner transfer to eliminate the static charge from the surface of the photosensitive drum.
The static eliminating device is often arranged between a charging device and a cleaning device removing adhesive, such as the toner, remained on the surface of the photosensitive drum after the toner transfer. Therefore, if rotating speed of the photosensitive drum is increased due to acceleration of the image forming apparatus, a time from the static elimination of the photosensitive drum by the static elimination device to next electrical charging in the charging device is remarkably shortened, and then, a carrier (static charge) trapped in a photosensitive layer may be insufficiently eliminated by the static elimination device. In such a case, next electrical charging is carried out while the carrier is remained on the photosensitive drum, and accordingly, there is a problem that a defective image called as the transfer memory image is easily occurred.
In order to solve this problem, there is an image forming apparatus configured so that the static eliminating device is positioned at an upstream side from the cleaning device in a rotating direction of the photosensitive drum to provide a wide interval from the static elimination device to the charging device, and then, to secure a sufficient time for removing the trapped carrier.
Ina case where the static eliminating device is arranged at the upstream side from the cleaning device, although the static eliminating device is positioned at a downstream side from a transferring device, a toner not transferred on a sheet and a toner scattered after the transfer onto the sheet are floated near the transferring device. If such non-transferred toner or scattered toner is adhered onto alight emitting part of the static eliminating device, there is a possibility of reducing a light amount of the static elimination light.
In order to solve such a problem, in a case where the static eliminating device is arranged at the upstream side from the cleaning device in the rotating direction of the photosensitive drum, a partition member is arranged between the static eliminating device and transfer device so that the static eliminating device does not directly face to the transferring device and a conveying path of the sheet, and accordingly, adhesion of the toner onto the light emitting part is prevented.
In a case of arranging the partition member, a space between a housing supporting the static elimination device and partition member provides an optical path of the static elimination light. A part of the static elimination light is reflected by faces at the optical path side (called as reflecting faces) of the housing and partition member and progressed, and then, radiated from an opening end between the housing and partition member to the photosensitive drum. Since the light amount of the static elimination light radiating to the photosensitive drum depends upon reflectance of the reflecting faces of the housing and partition member, the light amount of the static elimination light is increased as the reflectance of the reflecting faces is heightened. In addition, since the reflectance depends upon glossiness of the reflecting faces, the reflectance is heightened as the glossiness of the reflecting faces is heightened.
When an image forming operation is continued, the non-transferred toner or scattered toner may penetrate the optical path of the static elimination light from the opening end between the housing and partition member or the other regardless of the arrangement of the partition member.
For example, in a drum unit including the charging device, cleaning device and static elimination device in a body, the static elimination device is supported by a supporting part formed in an outer face of a housing of the drum unit, in accordance with a structure of a die used for molding the housing, an opening may be formed in apart of the supporting part. In such a case, by rotation of the photosensitive drum, a wind along the rotating direction of the photosensitive drum is occurred near the surface of the photosensitive drum. Moreover, a wind path is generated so that the wind penetrates the optical path of the static elimination light from the opening end between the housing and partition member, and then, runs out from the opening formed in the supporting part. If the scattered toner penetrates the optical path along the wind path, there are problems that the penetrated toner is adhered onto the reflecting faces of the housing and partition member, and accordingly, the reflectance of the reflecting faces is decreased.
Further, since the toner amount adhered onto the reflecting faces is uneven in an axial direction of the photosensitive drum, the reflectance is remarkably decreased at a place with much toner adhesion amount and the reflectance is hardly decreased at a place with little toner adhesion amount. Therefore, the light amount of the static elimination light being radiated onto the surface of the photosensitive drum is varied in the axial direction of the photosensitive drum, and then, surface electrical potential on the photosensitive drum after the static elimination becomes uneven. As a result, there is a possibility that a defective image, such as white void in a place with high surface electrical potential, is occurred.
In accordance with an embodiment of the present disclosure, a static eliminating device includes a light emitting part and an optical path providing part. The light emitting part emits a static eliminating light to a surface of an image carrier. The optical path providing part includes a reflecting face reflecting the static eliminating light and a radiation end from which the static eliminating light is radiated to the surface of the image carrier. The reflecting face is a matted face.
In accordance with an embodiment of the present disclosure, an image forming apparatus includes a static eliminating device. The static eliminating device includes a light emitting part and an optical path providing part. The light emitting part emits a static eliminating light to a surface of an image carrier. The optical path providing part includes a reflecting face reflecting the static eliminating light and a radiation end from which the static eliminating light is radiated to the surface of the image carrier. The reflecting face is a matted face.
The above and other objects, features, and advantages of the present disclosure will become more apparent from the following description.
In the following, with reference the drawings, a static eliminating device and an image forming apparatus according to an embodiment of the present disclosure will be described.
First, with reference to
As shown in
In an upper part of the printer main body 2, an exposure device 7 is located below the sheet ejected tray 4. Below the exposure device 7, an image forming part 8 is arranged. In the image forming part 8, a photosensitive drum 10 as an image carrier is rotatably arranged. Around the photosensitive drum 10, a charging device 11, a development device 12 as an attachment member, a transfer roller 13, a static eliminating device 14 and a cleaning device 15 are located in order along a rotating direction (refer to an arrow X in
Inside the printer main body 2, a conveying path 16 for the sheet is arranged. At an upstream end in the conveying path 16, a sheet feeder 17 is positioned. At an intermediate stream part in the conveying path 16, a transferring part 18 composed of the photosensitive drum 10 and transfer roller 13 is positioned. At a downstream part in the conveying path 16, a fixing device 19 is positioned. At a downstream end in the conveying path 16, a sheet ejecting part 20 is positioned. Below the conveying path 16, an inversion path 21 for duplex printing is arranged.
When the power is supplied to the printer 1, initial determination, such as temperature determination of the fixing device 19, is carried out. Subsequently, in the printer 1, when a printing start is directed, image forming operation is carried out as follows.
First, the surface of the photosensitive drum 10 is electric-charged by the charging device 11. Then, photographic exposure corresponding to image data on the photosensitive drum 10 is carried out by a laser light (refer to a two-dot chain line p in
On the other hand, the sheet picked up from the sheet feeding cartridge 3 by the sheet feeder 17 is conveyed to the transferring part 18 in a suitable timing for the above-mentioned image forming operation, and then, the toner image on the photosensitive drum 10 is transferred onto the sheet in the transferring part 18. The sheet with the transferred toner image goes into the fixing device 19, and then, the toner image is fixed on the sheet in the fixing device 19. The sheet with the fixed toner image is ejected from the sheet ejecting part 20 to the sheet ejected tray 4. An electrical potential remained on the photosensitive drum 10 in the image forming process is eliminated by the static eliminating device 14. The toner remained on the photosensitive drum 10 is collected by the cleaning device 15.
Next, with reference to
The housing 31 is a box-like member elongated in the left and right directions and includes left and right side boards 32L and 32R, a small frame part 33 and a large frame part 34. The side boards 32L and 32R face to each other at an interval equal to a length in an axial direction of the photosensitive drum 10. The small frame part 33 and large frame part 34 are bridged between the left and right side boards 32L and 32R. As a material of the housing 31, high impact polystyrene (HIP) may be applied.
In front lower portions of the left and right side boards 32L and 32R, bearing parts 32a are formed.
As shown in
The large frame part 34 is a member elongated in the left and right directions and has an upper concave part 34a formed in roughly U-shape in the side view and a lower concave part 34b formed in roughly U-shape in the side view, which are arranged vertically. The large frame part 34 is located so that a front opening of the upper concave part 34a faces to an outer face of the small frame part 33 and left and right openings of the lower concave part 34b face to the bearing parts 32a of the left and right side boards 32L and 32R. Both left and right ends of the large frame part 34 are fixed to the left and right sideboards 32L and 32R. Thereby, both left and right ends of a concave part surrounded by the upper concave part 34a and small frame part 33 are closed by the left and right side boards 32L and 32R to forma storing part (an upper storing part) 34c in the large frame part 34. In addition, both left and right ends of the lower concave part 34b are closed by the left and right side boards 32L and 32R to form a storing part 34d (a lower storing part) in the large frame part 34.
A lower piece 35 (hereinafter, called as a housing lower piece 35) of the lower concave part 34b in large frame part 34 is formed in a roughly flat plate shape and has a flat lower face 35a. The lower face 35a is subjected to matting treatment so as to obtain predetermined glossiness. In the lower face 35a of the housing lower piece 35, a supporting part 36 is formed. The supporting part 36 is formed so as to extend in the left and right directions at a rear side position of the lower face 35a. The supporting part 36 is formed in a L-shaped side view and has a base part 36a extending downward from the lower face 35a and a leading part 36b extending forward from a leading end of the base part 36a.
The photosensitive drum 10 has a rotation shaft 10a supported by the bearing parts 32a of the left and right side boards 32L and 32R (refer to
The charging device 11 includes a charging roller 11a and a charge cleaning roller 11b and is supported in the storing part 33b of the small frame part 33 of the housing 31. The charging roller 11a contacts and electrically charges the photosensitive drum 10. The charging roller 11a faces to a lower end of the storing part 33b to contact with a surface of the photosensitive drum 10 and the charge cleaning roller 11b is positioned at a depth side (an inner side) of the storing part 33b.
The cleaning device 15 includes a cleaning blade 15a, a cleaning roller 15b, a feeding roller 15c, a regulating member 15d and a collecting spiral 15e. The cleaning blade 15a comes into contact with the surface of the photosensitive drum 10 to scrap the remained toner. The cleaning roller 15b applies the toner to the surface of the photosensitive drum 10. The feeding roller 15c feeds the toner to the cleaning roller 15b. The regulating member 15d regulates a toner amount of the cleaning roller 15b. The collecting spiral 15e collects the scraped toner.
The cleaning blade 15a is supported by a supporting member 15f so as to come into contact with the surface of the photosensitive drum 10 in a counter direction to rotation of the photosensitive drum 10. The supporting member 15f is supported in the upper storing part 34c of the large frame part 34.
The cleaning roller 15b is positioned so as to face to the front end of the lower storing part 34d and to contact with the photosensitive drum 10. Along the external circumference of the cleaning roller 15b, the feeding roller 15c and regulating member 15d are positioned. The collecting spiral 15e is positioned at a deepest side (an innermost side) of the lower storing part 34d.
The static eliminating device 14 includes a light emitting part 41 emitting a static eliminating light to the surface of the photosensitive drum 10 and an optical path providing part 45 providing an optical path of the static eliminating light.
With reference to
The light emitting part 41 has illuminants 42 emitting the static eliminating light and a substrate 43 to which the illuminants 42 are attached. As the illuminants 42, a plurality of light emitting device (LED) chips may be applied. The substrate 43 has a length roughly equal to the length in the axial direction of the photosensitive drum 10. In a lower face of the substrate 43, a plurality of the illuminants 42 are packaged at predetermined intervals. As shown in
As shown
As shown in
The partition board 47 is a rectangular flat board having a flat face shape elongated in the left and right directions. The partition board 47 has a length in the left and right directions (width) being roughly equal to the length of the substrate 43 of the light emitting part 41 and a length in the forward and backward directions being roughly equal to a length in the forward and backward directions of the housing lower piece 35. Along a front edge of the partition board 47, a plurality of claws 47b are formed at predetermined intervals. The claws 47b are separating claws separating the sheet adhered on the photosensitive drum 10 after the toner transfer. In the vicinity of both ends of the front edge, positioning recess parts (positioning part) 47c to the large frame part 34 are formed. In a left edge of the partition board 47, a protruding piece 47d protruding outside is formed. The protruding piece 47d is configured to hind an end part of the substrate 43 of the light emitting part 41 when the partition board 47 is attached to the large frame part 34.
The partition board 47 is formed by matted polycarbonate (PC) or matted polyethylene terephthalate (PET) to have glossiness as that in a condition where a certain toner is adhered in advance.
The lower face 35a of the housing lower piece 35, similarly to the partition board 47, is subjected to the matting treatment is applied so as to have the glossiness in a condition where a certain toner is adhered in advance. The matting treatment is a surface treatment manner preventing the reflection of the light and is carried out in order to decrease the glossiness. As concrete examples of the treatment manner, embossing treatment forming wrinkle pattern on the surface, blackening treatment or the like may be cited.
Next, an action of the static eliminating device 14 having an above-mentioned configuration will be described with reference to
When the light is emitted from the illuminants 42 of the light emitting part 41 of the static eliminating device 14 at a predetermined radiation angle, as indicated by two-dot chain lines in
When the image forming operation is repeated, a non-transferred toner or a scattered toner is floated near the static eliminating device 14. By the rotation of the photosensitive drum 10, an air current along the rotation direction is generated around the surface of the photosensitive drum 10. In a case where a wind path from the radiation end OP of the optical path to the back side of the light emitting part 41 is generated, as indicated by a solid line arrow A in
As described above, in the printer 1 according to the embodiment of the present disclosure, since the upper face 47a of the partition board 47 and the lower face 35a of the housing lower piece 35 as the reflecting faces have the same glossiness as that in a condition where a certain toner is adhered in advance, if the toner is adhered on the faces, decreasing degree of the glossiness is small. Therefore, if adhesion amounts of the toner penetrating the optical path are different in the left and right directions, since a difference in light amounts of the static eliminating light caused due to the difference of the adhesion amounts is hardly generated in the left and right directions, it is possible to radiate the static eliminating light with roughly even light amounts in the left and right directions.
In this static eliminating device 14, although the light amount of the static eliminating light radiated to the surface of the photosensitive drum 10 may be decreased, there is no problem since the light amount of the degree enough to eliminate remained electrical potential may be secured. Even if the light amount is decreased, it is preferable to radiate the static eliminating light with roughly equal light amounts in the left and right directions, in comparison with a case of different light amounts in the left and right directions. Incidentally, the decrease in the light amount of the static eliminating light can be compensated by using the light emitting parts with large power or other means.
Next, with reference to
In this static eliminating device 14′, a supporting part 51 supporting the partition board 47 is formed in the lower face 35a of the housing lower piece 35. The supporting part 51 includes, as shown in
As shown in
The left and right side walls 53 and 54 are formed so as to extend in the forward and backward directions at both left and right sides of the light emitting part 41. Rear ends of the left and right side walls 53 and 54 are connected to the both left and right ends of the rear wall 52. Heights of the left and right side walls 53 and 54 are equal to the height of the rear wall 52. Respective lower faces 53a and 54a of the left and right side walls 53 and 54 and a lower face 52c of the leading part 52b of the rear wall 52 constitute a continuous flat face.
The partition board 47 is attached to the lower face 52c of the rear wall 52 and the lower faces 53a and 54a of the left and right side walls 53 and 54 in the supporting part 51 by a double sided tape, a gluing or the like, in a state of directing the claws 47b forward. Thereby, a space is provided so as to be surrounded vertically by the housing lower piece 35 and partition board 47 and to be surrounded horizontally by the left and right side walls 53 and 54. The back side of the space is surrounded by the back wall 52 and the front side of the space is opened to face to the photosensitive drum 10. This space provides the optical path of the static eliminating light. The upper face 47a of the partition board 47 and the lower face 35a of the housing lower piece 35 provide the reflecting faces of the static eliminating light. The front end facing to the surface of the photosensitive drum 10 provides the radiation end OP of the static eliminating light.
In the static eliminating device 14′ of this other example, the optical path are closed except for the radiation end OP. Therefore, when the air current (refer to an arrow B1 in
In the above-described embodiments of the present disclosure, as the material of the partition board 47, originally matted material is used and the glossiness of the lower face 35a of the housing lower piece 35 is reduced by the matting treatment. However, reduction manner of the glossiness of the partition board 47 and housing 31 is restricted from these. A quality or color of the material of the partition board 47 and housing 31 may be suitable chosen, or treatment manner may be chosen according to the quality or color of the material. Alternatively, the originally matted material may be subjected to the matting treatment. Further alternatively, only the reflecting face of the partition board 47 may be subjected to the matting treatment.
Although, in the embodiments, the glossiness of both the partition board 47 and housing 31 is reduced, the glossiness of only the partition board 47 may be reduced. As described above, since the toner penetrating the optical path easily falls to the partition board 47 by the gravitation to be adhered, it is possible to obtain excellent effect by subjecting only the partition board 47 to the treatment reducing the glossiness.
Although, in the embodiment, the example of reducing the glossiness of the partition board 47 and housing 31 and closing the wind path of the static eliminating device 14 was described, it is possible to obtain excellent effect by only closing the wind path. Therefore, in a case where the glossiness of the reflecting face cannot be reduced to a predetermined value due to material of the partition board 47 and housing 31 and others, it is preferable to apply the manner of closing the wind path together with the reduction of the glossiness.
The embodiment was described in a case of applying the configuration of the present disclosure to the printer 1. On the other hand, in another embodiment, the configuration of the disclosure may be applied to another image forming apparatus, such as a copying machine, a facsimile or a multifunction peripheral, except for the printer 1.
While the present disclosure has been described with reference to the particular illustrative embodiments, it is not to be restricted by the embodiments. It is to be appreciated that those skilled in the art can change or modify the embodiments without departing from the scope and spirit of the present disclosure.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2013-156911 | Jul 2013 | JP | national |
