JP6269453B2 - Image forming apparatus, light guide member - Google Patents

Description

  The present invention relates to an electrophotographic image forming apparatus and a light guide member used therefor.

  In the electrophotographic image forming apparatus, the photosensitive drum is uniformly charged by the charging roller. Next, laser light is irradiated on the surface of the charged photosensitive drum to form an electrostatic latent image on the surface of the photosensitive drum. Then, the electrostatic latent image on the photosensitive drum is developed using toner. Thereafter, when the toner image on the photosensitive drum is transferred to a transfer member such as a sheet or an intermediate transfer belt, the photosensitive drum is neutralized by the neutralizing light emitted from the neutralizing unit, and the surface of the photosensitive drum is cleaned by the cleaning unit. To be cleaned.

  Further, there may be provided a static elimination unit that applies static elimination light to the photosensitive drum before the toner image on the photosensitive drum is transferred to the transfer member (see, for example, Patent Document 1). Further, the light irradiated from the light source is irradiated with the light guide member on which the two reflection surfaces are formed, the position after the transfer of the toner image on the photosensitive drum on the upstream side in the running direction of the member to be transferred and the downstream side in the running direction. A configuration is known in which the toner image is reflected toward the position before transfer of the toner image on the photosensitive drum (see, for example, Patent Document 2).

JP 2011-221405 A JP2013-113901A

  However, in the configuration in which the two reflecting surfaces are formed on the light guide member, there is a problem that the mold shape for forming the light guide member becomes complicated.

  An object of the present invention is to provide an image forming apparatus capable of simplifying the configuration for performing pre-transfer charge removal and post-transfer charge removal, and a light guide member used therefor.

  An image forming apparatus according to one aspect of the present invention includes a plurality of image carriers, a developing roller, a transfer roller, a cleaning unit, a light source, and a light guide member. The image carriers are arranged side by side along the traveling direction of the member to be transferred. The developing roller develops an electrostatic latent image formed on each of the image carriers as a toner image. The transfer roller transfers the toner image formed on each of the image carriers to the transfer target member. The cleaning unit cleans each of the image carriers after the transfer of the toner image onto the transfer target member by the transfer roller. The light source irradiates light used for neutralizing each of the image carriers. The light guide member transmits and reflects light incident on one end in the longitudinal direction from each of the light sources and guided to the other end, and the developing roller in the image carrier on the downstream side in the running direction of the transferred member; A long member having a transmission / reflection portion that irradiates a position between the transfer roller and a position between the transfer roller and the cleaning portion in the image carrier on the upstream side in the running direction of the transfer member. It is.

  A light guide member according to another aspect of the present invention includes a plurality of image carriers arranged side by side along a traveling direction of a member to be transferred, and electrostatic latent images formed on the image carriers as toner images. A developing roller for developing, a transfer roller for transferring the toner image formed on each of the image carriers to the member to be transferred, and the image holding after transfer of the toner image to the member to be transferred by the transfer roller It is a long member used in an image forming apparatus including a cleaning unit that cleans each body and a light source that irradiates light used for neutralizing each image carrier. The light guide member transmits and reflects light incident on one end in the longitudinal direction from each of the light sources and guided to the other end, so that the development in the image carrier on the downstream side in the running direction of the transferred member is performed. A transmission / reflection unit that irradiates a position between the transfer roller and the transfer roller, and a position between the transfer roller and the cleaning unit in the image carrier on the upstream side in the running direction of the transfer target member;

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the image forming apparatus which can simplify the structure for performing static elimination before transfer, and static elimination after transfer, and a light guide member used for this.

FIG. 1 is a diagram illustrating a configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a diagram illustrating an example of an image forming unit of the image forming apparatus illustrated in FIG. FIG. 3 is a diagram illustrating a charge removal unit of the image forming unit illustrated in FIG. 2. FIG. 4 is a diagram illustrating a light guide member of the static elimination unit illustrated in FIG.

  Embodiments of the present invention will be described below with reference to the accompanying drawings for understanding of the present invention. In addition, the following embodiment is an example which actualized this invention, Comprising: The thing of the character which limits the technical scope of this invention is not.

  As shown in FIG. 1, the image forming apparatus 10 includes a plurality of sets of image forming units 1 to 4, an intermediate transfer belt 5, an optical scanning device 6, a secondary transfer roller 7, a fixing device 8, a paper discharge tray 9, and a toner container. 21 to 24, a paper feed cassette 31, a transport path 32, and the like. The image forming apparatus 10 is a color printer that forms a color image or a monochrome image based on image data input from an information processing apparatus such as a personal computer on a sheet supplied from a paper feed cassette 31 along a conveyance path 32. . In addition, a facsimile machine, a copier, and a multifunction machine are examples of the image forming apparatus according to the present invention.

  The image forming units 1 to 4 are juxtaposed along the traveling direction D1 of the intermediate transfer belt 5, and constitute a so-called tandem image forming unit. Specifically, a toner image corresponding to Y (yellow) in the image forming unit 1, M (magenta) in the image forming unit 2, C (cyan) in the image forming unit 3, and K (black) in the image forming unit 4 is formed. Is done. In the present embodiment, the intermediate transfer belt 5 is described as an example of a member to be transferred. However, a sheet such as a printing sheet may be an example of a member to be transferred. That is, a configuration in which a toner image is transferred to a sheet conveyed by a sheet conveying belt is considered as another embodiment.

  FIG. 2 is a schematic diagram showing a schematic configuration of the image forming unit 1 and the image forming unit 2. As shown in FIG. 2, the image forming unit 1 and the image forming unit 2 include a photosensitive drum 11, a charging unit 12, a developing unit 13, a charge eliminating unit 14, and a primary transfer roller provided corresponding to the photosensitive drum 11. 15 and an electrophotographic image forming unit including a cleaning device 16. Since the image forming unit 3 and the image forming unit 4 are configured in the same manner, the description thereof is omitted here.

  Each of the photosensitive drums 11 is an image carrier that is arranged in parallel along the traveling direction of the intermediate transfer belt 5 and carries an electrostatic latent image and a toner image. Each charging unit 12 includes a charging roller 121 that charges the photosensitive drum 11 with electric power supplied from a power source (not shown). The photosensitive drum 11 charged by the charging unit 12 is irradiated with laser light by the optical scanning device 6, and an electrostatic latent image based on the image data is formed on the outer peripheral surface of the photosensitive drum 11. Each developing unit 13 includes a developing roller 131 that develops the electrostatic latent image formed on the photosensitive drum 11 with toner (developer). For developing the electrostatic latent image by the developing unit 13, an external additive such as a lubricant or an abrasive is used together with the toner. Each developing unit 13 is supplied with toner from removable toner containers 21 to 24 corresponding to the respective colors.

  Each primary transfer roller 15 transfers the toner image formed on the photosensitive drum 11 to the intermediate transfer belt 5. The intermediate transfer belt 5 is an intermediate transfer member that runs above the photosensitive drums 11 of the image forming units 1 to 4 and to which toner images of respective colors formed on the photosensitive drums 11 are sequentially superimposed and transferred. . The toner image on the intermediate transfer belt 5 is transferred by the secondary transfer roller 7 to a sheet conveyed from the paper feed cassette 31 via the conveyance path 32. Thereafter, the toner image transferred to the sheet is heated by the fixing device 8 and melted and fixed on the sheet. Each of the cleaning devices 16 includes a cleaning unit 161 such as a cleaning roller or a cleaning blade for cleaning the photosensitive drum 11 after the toner image is transferred to the intermediate transfer belt 5 by the primary transfer roller 15.

  Each of the static elimination units 14 is for neutralizing the photosensitive drum 11 at a position between the primary transfer roller 15 and the cleaning unit 161 on the outer peripheral surface of the photosensitive drum 11 on the upstream side in the traveling direction D1 of the intermediate transfer belt 5. Irradiate the static elimination light L1. In other words, each of the static elimination units 14 irradiates the static elimination light L <b> 1 on the downstream side of the primary transfer roller 15 and the upstream side of the cleaning unit 161 in the rotation direction of the photosensitive drum 11. Further, each of the static elimination units 14 neutralizes the photosensitive drum 11 at a position between the developing roller 131 and the primary transfer roller 15 on the outer peripheral surface of the photosensitive drum 11 on the downstream side in the traveling direction D1 of the intermediate transfer belt 5. Irradiation light L2 is emitted. In other words, each of the static elimination units 14 irradiates the static elimination light L <b> 2 on the downstream side of the developing roller 13 and the upstream side of the primary transfer roller 15 in the rotation direction of the photosensitive drum 11. In this manner, the so-called memory image of the photosensitive drum 11 is suppressed by eliminating the charge of the photosensitive drum 11 before and after the transfer of the toner image on the photosensitive drum 11 to the intermediate transfer belt 5.

  Incidentally, since the yellow image is not conspicuous, the problem of the image memory is not easily revealed even if the neutralizing light L2 is not irradiated on the photosensitive drum 11 of the image forming unit 1 corresponding to yellow. For this reason, in the image forming apparatus 10, the disposition of the neutralizing unit 14 that irradiates the photosensitive drum 11 of the image forming unit 1 with the neutralizing light L <b> 2 is omitted. In other words, in the image forming apparatus 10, the photosensitive drum 11 disposed on the most upstream side in the traveling direction D1 corresponds to yellow, and the light source 141 is provided only at the downstream position of each of the photosensitive drums 11 in the traveling direction D1. And the static elimination part 14 containing the light guide member 142 is arrange | positioned. Of course, it is also conceivable that the image forming apparatus 10 includes a static elimination unit 14 that irradiates the photosensitive drum 11 of the image forming unit 1 with the static elimination light L2.

  Next, the charge removal unit 14 will be described with reference to FIGS. 3 and 4. Here, FIG. 3 is a plan view showing the configuration of the charge removal unit 14, and FIG. 4 is a perspective view showing the configuration of the light guide member 142.

  The neutralization unit 14 is disposed between the photosensitive drum 11 disposed on the upstream side in the traveling direction D2 of the intermediate transfer belt 5 and the photosensitive drum 11 disposed on the downstream side in the traveling direction D2 of the intermediate transfer belt 5. ing. The neutralization unit 14 includes a light guide member 142 that is long in the axial direction D2 of the light source 141 and the photosensitive drum 11. The light guide member 142 is longer than the photosensitive drum 11, and is arranged so that the longitudinal direction is parallel to the axial direction D <b> 2 of the photosensitive drum 11.

  The light source 141 is an LED light source that emits light for neutralizing the photosensitive drum 11. Light emitted from the light source 141 enters a light incident surface 143 formed at one end of the light guide member 142 in the longitudinal direction. In the light guide member 142, light incident from one end where the light incident surface 143 is formed is repeatedly reflected and guided toward the end surface 144 at the other end. In the present embodiment, the case where the light source 141 is provided at one end of the light guide member 142 will be described as an example. However, the light source 141 is provided at both ends of the light guide member 142, and the light incident surface 143 and the end surface are provided. A configuration in which light is incident from both of 144 is also conceivable as another embodiment.

  The light guide member 142 is a substantially cylindrical member having a D-shaped cross section (a bowl shape) having a flat surface 145 and a curved surface 146, and is formed of a material such as a resin. A plurality of transmission / reflection portions 147 are formed on the plane 145 at predetermined intervals in the longitudinal direction.

  Specifically, the transmission / reflection portion 147 is an inclined surface formed at a predetermined inclination angle inward from the flat surface 145. The inclination angle of the transmission / reflection part 147 is appropriately determined so that the transmission amount and reflection amount of the light irradiated from the light source 141 by the transmission / reflection part 147 have a predetermined relationship. For example, the inclination angle of the transmission / reflection portion 147 is such that the amount of the neutralizing light L1 reaching the photosensitive drum 11 upstream in the traveling direction D1 of the intermediate transfer belt 5 and the downstream photosensitive member in the traveling direction D1 of the intermediate transfer belt 5. It is determined so that the ratio of the amount of the neutralizing light L2 reaching the drum 11 is 1:10.

  In the static elimination unit 14, the light irradiated from the light source 141 is reflected by the transmission / reflection unit 147, and the primary transfer roller 15 on the outer peripheral surface of the photosensitive drum 11 on the upstream side in the traveling direction D 1 of the intermediate transfer belt 5. A position between the cleaning device 16 and the photosensitive drum 11 is irradiated as a neutralizing light L1 for neutralizing the photosensitive drum 11.

  Further, in the static elimination unit 14, the light irradiated from the light source 141 is transmitted by the transmission / reflection unit 147, and the developing roller 131 and the primary roller on the outer peripheral surface of the photosensitive drum 11 on the downstream side in the traveling direction D <b> 1 of the intermediate transfer belt 5. A position between the transfer roller 15 and the photosensitive drum 11 is irradiated as a neutralizing light L2 for neutralizing the photosensitive drum 11.

  On the other hand, in the configuration in which the two reflecting surfaces are formed on the light guide member as in the related art described above, there is a problem that the mold shape for forming the light guide member becomes complicated. However, in the image forming apparatus 10, since the light guide member 142 is formed with only one plane 145 having the transmission / reflection part 147, the mold shape for molding the light guide member 142 can be simplified. .

  It is also conceivable that the light guide member 142 is arranged in a state rotated by 180 degrees. That is, the static elimination unit 14 reflects the light emitted from the light source 141 by the transmission / reflection unit 147, and performs the primary transfer with the developing roller 131 on the outer peripheral surface of the photosensitive drum 11 on the downstream side in the running direction D 1 of the intermediate transfer belt 5. It is conceivable to irradiate the position between the roller 15 with the static elimination light L2. In this case, the static elimination unit 14 transmits the light emitted from the light source 141 through the transmission / reflection unit 147, and the primary transfer roller 15 on the outer peripheral surface of the photosensitive drum 11 on the upstream side in the traveling direction D 1 of the intermediate transfer belt 5. The neutralizing light L <b> 1 is irradiated to the position between the cleaning device 16.

  By the way, in the light guide member 142, the light quantity gradually decreases while the light incident from the light source 141 is guided from one end to the other end. Therefore, in the light guide member 142, the interval P <b> 1 where the transmission / reflection portion 147 is formed in the longitudinal direction becomes shorter as the distance from the light source 141 increases. As a result, since the amount of light reflected and transmitted by the transmission / reflection part 147 increases at a position far from the light incident surface 143 of the light guide member 142, the static elimination light L 1 and the static elimination light L 2 in the longitudinal direction of the light guide member 142 are increased. Uniformity is achieved. Further, as a configuration for achieving uniformization of the static elimination light L1 and static elimination light L2 emitted from the light guide member 142, the size of the transmission / reflection part 147 may be increased as the distance from the light source 141 increases.

  Further, when there is a shortage of static elimination light irradiated from the vicinity of the end of the light guide member 142 on the light source 141 side to the image forming area A1 of the photosensitive drum 11 on the downstream side in the running direction D1 of the intermediate transfer belt 5, There is a possibility that homogenization is hindered. Specifically, in the light guide member 142, the static elimination light L <b> 2 that has passed through the transmission / reflection part 147 is directed to the photosensitive drum 11 at a certain angle, and therefore, at the end of the image forming area A <b> 1 of the photosensitive drum 11. There is a possibility that the amount of light to be irradiated is reduced compared to other regions.

  Further, when strong neutralizing light is irradiated from the vicinity of the end of the light guide member 142 on the light source 141 side to the image forming area A1 of the photosensitive drum 11 on the upstream side in the traveling direction D1 of the intermediate transfer belt 5, the static eliminating light is emitted. There is a possibility that the homogenization of hindered. Specifically, of the curved surface 146 of the light guide member 142, light having a high intensity that is close to the light source 141 and emitted from the light source 141 is an image forming area A1 on the photosensitive drum 11 on the upstream side in the traveling direction D1 of the intermediate transfer belt 5. If the value reaches, the uniformity of the charge removal amount in the image forming area A1 may be hindered.

  Therefore, the light diffusion member 148 is formed in the light guide member 14 at a position corresponding to the non-image forming area A2 outside the image forming area A1 of the photosensitive drum 11. The light diffusing unit 148 is a position facing the transmission / reflection unit 147, and is located outside a predetermined specific region corresponding to the non-image forming region A <b> 2 from one end or both ends in the longitudinal direction of the light guide member 152. It is the convex part of the cross-sectional arc shape formed toward the direction. For example, the light diffusion part 148 has a hemispherical shape. Further, the light diffusing unit 148 may have a shape obtained by cutting a part of a spherical shape or a spheroidal shape.

  Thereby, in the light guide member 142, the light reflected by the light diffusing unit 148 is discharged from the flat surface 145 to the end of the image forming area A 1 of the photosensitive drum 11 on the downstream side in the running direction D 1 of the intermediate transfer belt 5. As irradiated. Accordingly, it is possible to compensate for a shortage of light quantity at the end of the image forming area A1 of the photosensitive drum 11 on the downstream side in the running direction D1 of the intermediate transfer belt 5, and it is possible to make the charge removal amount uniform.

  Further, since the light transmitted from the light guide member 142 through the curved surface 146 is diffused by the light diffusing unit 148, the light reaches the image forming area A2 of the photosensitive drum 11 on the upstream side in the traveling direction D1 of the intermediate transfer belt 5 as the neutralizing light L1. The amount of light to be suppressed is suppressed. Therefore, it is possible to make uniform the amount of charge removed to the image forming area A1 of the photosensitive drum 11 on the upstream side in the running direction D1 of the intermediate transfer belt 5.

  As shown in FIG. 2, the static eliminator 14 is provided with a transparent or translucent translucent member 17 as a cover member that covers part or all of the light source 141 and the light guide member 142. This prevents dust or toner from adhering to the light source 141 and the light guide member 142 of the static elimination unit 14, thereby extending the life of the image forming apparatus 10.

1-4: Image forming unit 5: Intermediate transfer belt 6: Optical scanning device 7: Secondary transfer roller 8: Fixing device 9: Paper discharge tray 10: Image forming device 11: Photoconductor drum 12: Charging unit 121: Charging roller 13: Development unit 131: Development roller 14: Static elimination unit 141: Light source 142: Light guide member 15: Primary transfer roller 16: Cleaning device 161: Cleaning unit

Claims (7)

A plurality of image carriers arranged side by side along the traveling direction of the transfer member;
A developing roller for developing an electrostatic latent image formed on each of the image carriers as a toner image;
A transfer roller for transferring the toner image formed on each of the image carriers to the member to be transferred;
A cleaning unit that cleans each of the image carriers after the transfer of the toner image to the transfer member by the transfer roller;
A light source for irradiating light used for neutralizing each of the image carriers;
Between the developing roller and the transfer roller in the image carrier on the downstream side in the running direction of the transferred member by transmitting and reflecting the light incident on one end in the longitudinal direction from each light source and guided to the other end And a long section with a D-shaped cross section having a plane on which a transmission / reflection portion is formed to irradiate a position between the transfer roller and the cleaning portion of the image carrier on the upstream side in the running direction of the transfer member. A scale-shaped light guide member;
An image forming apparatus comprising: The transmission / reflection part is
For neutralizing the image carrier at a position between the transfer roller and the cleaning portion on the outer peripheral surface of the image carrier on the upstream side in the traveling direction of the transfer member. While reflecting as static elimination light,
For neutralizing the image carrier at a position between the developing roller and the transfer roller on the outer peripheral surface of the image carrier on the downstream side in the traveling direction of the transfer member. The image forming apparatus according to claim 1, wherein the image forming apparatus transmits light as static elimination light. The transmission / reflection part is
For neutralizing the image carrier at a position between the transfer roller and the cleaning portion on the outer peripheral surface of the image carrier on the upstream side in the traveling direction of the transfer member. While allowing it to pass through as static elimination light,
For neutralizing the image carrier at a position between the developing roller and the transfer roller on the outer peripheral surface of the image carrier on the downstream side in the traveling direction of the transfer member. The image forming apparatus according to claim 1, wherein the image forming apparatus is reflected as static elimination light.   The image forming apparatus according to claim 2, wherein the transmission / reflection portion is an inclined surface formed at a predetermined inclination angle inward from the plane.   The image forming apparatus according to claim 2, wherein an interval between the transmission / reflection portions is shortened as the distance from the light source increases.   The image forming apparatus according to claim 2, wherein a size of the transmission / reflection portion increases as the distance from the light source increases.   The image forming apparatus according to claim 1, further comprising a translucent member that covers part or all of the outer periphery of the light guide member.

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