JP2013101176A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus that carries out development by use of a photoreceptor belt and that is able to prevent meander of the photoreceptor belt.SOLUTION: The image forming apparatus for forming an image by an electrophotographic system comprises: a photoreceptor belt 1 in the form of an endless belt; a drive roller 2; a follower roller 3; a plurality of developing devices 9 corresponding to each color into which electrostatic latent images formed on the photoreceptor belt 1 are developed; charging means 7; and exposure means 8. In the image forming apparatus, a backing member 10 that is long in the lateral direction of the photoreceptor belt 1 is provided at a position opposite a developing roller 91, composing the developing device 9, via the photoreceptor belt 1. At both ends of the backing member 10 in the longitudinal direction thereof, positioning members 11 are provided for determining a clearance between the developing roller 91 and the photoreceptor belt 1. The positioning member 11 is arranged so as to sandwich the lateral end of the photoreceptor belt 1 between the backing member 10 and the positioning member 11.

Description

  The present invention relates to an image forming apparatus that employs an electrophotographic system, and more specifically, an image including a non-magnetic one-component developing device, in particular, a developing device that uses a developer carrier made of a rigid body such as metal for non-contact development. The present invention relates to a forming apparatus.

  2. Description of the Related Art Conventionally, in an image forming apparatus employing an electrophotographic method, an electrostatic latent image formed on the surface of a photoreceptor is visualized by supplying toner as a developer component from the developing device and developing it. A toner image that is an image is formed, the toner image is further transferred onto a recording paper that is a transfer medium, and the toner image transferred onto the recording paper is fixed to form a robust recording image.

  In recent years, with the widespread use of color inkjet image forming apparatuses, image forming apparatuses using an electrophotographic system are also required to be reduced in size and price. Under such circumstances, as a developing device for electrophotography, a non-magnetic one-component developing system that is simple in structure and capable of being miniaturized is useful, and development of an improved technique is ongoing.

  The non-magnetic one-component development system includes a contact development system in which development is performed in contact with a latent image carrier and a non-contact development system in which development is performed with a predetermined gap from the latent image carrier. Both of them have similar structures of the developing device and have a compact feature, but the material of the developing roller may be different.

  In the contact development method, the developing roller is composed of an elastic member such as conductive rubber in order to obtain uniform contact in the development region. In particular, a configuration using a rigid body such as a photosensitive drum as the electrostatic latent image carrier is effective from the viewpoint of preventing damage due to a failure in the contact state.

  In the case where the developing roller is a rubber roller, as the doctor blade for forming the toner layer on the developing roller, a roller blade made of a rubber blade or a metal shaft, a blade made of a single metal plate, or the like is used. Among them, a blade made of a metal plate is widely used because it can be provided at low cost.

  On the other hand, in the case of the non-contact developing method, since it is necessary to accurately maintain a gap with the electrostatic latent image carrier, a roller or sleeve made of a rigid body such as metal is often used as the developing roller. This is because it is more effective than the rubber roller for improving the polishing accuracy of the surface and suppressing the eccentricity of the drive shaft and the surface. Another reason is that there is no fear of injury due to contact because of non-contact.

  In the case of the non-contact development method, a development method in which a color image in which colors are superimposed is formed on one endless belt-like photoreceptor (hereinafter referred to as “photoreceptor belt”) and transferred to paper in one step; A so-called image-on-image process can be employed. Since the Image-On-Image process requires only a single photoreceptor belt, a simple and compact system can be provided. Further, since images of different colors are superimposed on one photosensitive belt, color misregistration can be suppressed, and the system is suitable for a high-speed full-color machine.

  In the developing process using the photosensitive belt, as a conventional technique, for example, a driving roller, a driven roller, a tension roller, and a backing member have been proposed (see Patent Document 1).

JP 2002-6620 A

  However, in the image forming apparatus disclosed in Patent Document 1, meandering of the photosensitive belt cannot be avoided when the driving roller is rotated. In order to suppress meandering of the photosensitive belt, there is a method in which a crown is provided on the drive roller or the like.

  There is also a method of stopping the movement of the photosensitive belt by providing flanges or collars on both sides of the drive roller, etc., and contacting the end of the photosensitive belt there, but contact the flange or collar of the photosensitive belt. The worn part is worn away by friction, causing damage.

  As another countermeasure, there is a method of providing a bead on the inner side of the photosensitive belt. However, it is costly, and if the bead portion runs on a driving roller or the like, the gap between the photosensitive belt and the developing roller is a predetermined value. This causes a problem that the image cannot be formed.

  The present invention has been made in view of the above-described conventional problems, and provides an image forming apparatus capable of preventing meandering of the photoreceptor belt in an image forming apparatus that performs development using the photoreceptor belt. For the purpose.

  An image forming apparatus according to the present invention for solving the above-described problems is as follows.

  The present invention provides an endless belt-like photoconductor on which an electrostatic latent image is formed, a driving roller for rotating the photoconductor, a bridging roller for applying tension to the photoconductor, and the photoconductor A plurality of developing devices corresponding to each color for supplying a developer to develop an electrostatic latent image formed on the photoconductor, a charging unit for applying a predetermined potential to the photoconductor, and the photoconductor An image forming apparatus for forming an image by an electrophotographic method, and exposing the photosensitive member to a position facing a developing roller constituting the developing device via the photosensitive member. A backing member that is long along the width direction of the body (perpendicular to the rotation direction (conveying direction) of the photosensitive member), and the developing roller and the photosensitive member are provided at both ends in the longitudinal direction of the backing member. It has a positioning member that determines the separation distance, and The positioning member, and is characterized in placing the widthwise end portion of the photosensitive member to sandwich between the backing member.

  The present invention also provides an endless belt-like photoconductor on which an electrostatic latent image is formed, a driving roller for rotating the photoconductor, a bridging roller for applying tension to the photoconductor, and the photoconductor. A plurality of developing devices corresponding to respective colors for supplying a developer to the photoconductor to develop an electrostatic latent image formed on the photoconductor, a charging unit for applying a predetermined potential to the photoconductor, and the photoconductor And an exposure unit for forming an electrostatic latent image on a body, wherein the exposure unit includes a plurality of the exposure units corresponding to the plurality of developing devices, A backing member that is long along the width direction of the photoconductor is provided at a position facing the exposure means via the photoconductor, and the exposure means and the photoconductor are spaced apart at both ends in the longitudinal direction of the backing member. A positioning member for determining the distance; Member is an end portion in the width direction of the photosensitive member which is characterized in that arranged to sandwich between the backing member.

  The present invention also provides an endless belt-like photoconductor on which an electrostatic latent image is formed, a driving roller for rotating the photoconductor, a bridging roller for applying tension to the photoconductor, and the photoconductor. A plurality of developing devices corresponding to respective colors for supplying a developer to the photoconductor to develop an electrostatic latent image formed on the photoconductor, a charging unit for applying a predetermined potential to the photoconductor, and the photoconductor An image forming apparatus that forms an image by an electrophotographic method, and includes a plurality of the charging means corresponding to the plurality of developing devices, A backing member that is long along the width direction of the photosensitive member is provided at a position facing the charging unit via the photosensitive member, and the charging unit and the photosensitive member are separated at both ends in the longitudinal direction of the backing member. A positioning member for determining the distance; Member is an end portion in the width direction of the photosensitive member which is characterized in that arranged to sandwich between the backing member.

  Further, the present invention preferably includes a pressing member that presses the positioning member in the direction of the backing member, and the pressing force of the positioning member is increased as it is closer to the driving roller.

  In the present invention, it is preferable that the pressing force of the positioning member is adjusted by a force that abuts the developing roller, the exposure unit, or the charging unit against the positioning member.

  In the present invention, it is preferable that a sliding member is disposed between the positioning member and the photoconductor.

In the present invention, it is preferable that the positioning member is formed such that the length along the width direction of the photoconductor becomes longer as the length is closer to the driving roller.
Specifically, it may be formed such that the closer to the developing roller, the narrower the central side of the photoconductor.

  According to the present invention, the positioning member is formed with an inclined surface in which the surface of the positioning member facing along the width direction of the photoconductor becomes narrower as the distance between the facing positioning members toward the drive roller side becomes narrower. It is preferable to do.

  According to the image forming apparatus of the present invention, an endless belt-like photoconductor on which an electrostatic latent image is formed, a driving roller for rotating the photoconductor, and a bridging roller for applying tension to the photoconductor A plurality of developing devices corresponding to each color for supplying a developer to the photoconductor to develop an electrostatic latent image formed on the photoconductor, and a charging unit for applying a predetermined potential to the photoconductor And an exposure means for forming an electrostatic latent image on the photoconductor, and an image forming apparatus for forming an image by an electrophotographic method, a developing roller constituting the developing device via the photoconductor Provided with a long backing member along the width direction of the photoconductor at opposing positions, and provided with positioning members at both ends in the longitudinal direction of the backing member to determine a separation distance between the developing roller and the photoconductor, The positioning member is connected to the photoreceptor. By placing the end portion in the width direction so as to sandwich between said backing member, said to stabilize the conveyance of the photosensitive member by sandwiching both ends of the photosensitive member, it is possible to prevent the meandering of the photosensitive member.

  In addition, according to the image forming apparatus of the present invention, an endless belt-like photoconductor on which an electrostatic latent image is formed, a driving roller for rotating the photoconductor, and a tension for applying tension to the photoconductor. A bridging roller, a plurality of developing devices corresponding to each color for supplying a developer to the photoconductor to develop an electrostatic latent image formed on the photoconductor, and for applying a predetermined potential to the photoconductor In an image forming apparatus that includes a charging unit and an exposure unit for forming an electrostatic latent image on the photoconductor, and performs image formation by an electrophotographic method, the exposure unit corresponds to the plurality of developing devices. A plurality of long backing members along the width direction of the photoconductor at positions facing the exposure means via the photoconductor, and the exposure means at both ends in the longitudinal direction of the backing member. Positioning unit for determining a separation distance from the photosensitive member And positioning the positioning member so that the end in the width direction of the photoreceptor is sandwiched between the backing member, thereby stabilizing the conveyance of the photoreceptor by sandwiching both ends of the photoreceptor, The meandering of the photoreceptor can be prevented.

  In addition, according to the image forming apparatus of the present invention, an endless belt-like photoconductor on which an electrostatic latent image is formed, a driving roller for rotating the photoconductor, and a tension for applying tension to the photoconductor. A bridging roller, a plurality of developing devices corresponding to each color for supplying a developer to the photoconductor to develop an electrostatic latent image formed on the photoconductor, and for applying a predetermined potential to the photoconductor In an image forming apparatus that includes a charging unit and an exposure unit for forming an electrostatic latent image on the photosensitive member and performs image formation by an electrophotographic method, the charging unit corresponds to the plurality of developing devices. A plurality of long backing members along the width direction of the photoconductor at positions facing the charging means via the photoconductor, and the charging means at both ends in the longitudinal direction of the backing member. Positioning unit for determining a separation distance from the photosensitive member And positioning the positioning member so that the end in the width direction of the photoreceptor is sandwiched between the backing member, thereby stabilizing the conveyance of the photoreceptor by sandwiching both ends of the photoreceptor, The meandering of the photoreceptor can be prevented.

  Further, according to the present invention, a pressing member that presses the positioning member in the direction of the backing member is provided, and the pressing force of the positioning member is increased as it is closer to the driving roller, so Effective in preventing meandering.

  Further, according to the present invention, the meandering of the photoconductor is prevented by adjusting the pressing force of the positioning member by a force that abuts the developing roller, the exposure unit, or the charging unit against the positioning member. However, it is possible to improve the accuracy of the positional relationship between the exposure unit and the photoconductor.

  In addition, according to the present invention, it is possible to reduce the film thickness reduction of the photoconductor by disposing a sliding member between the positioning member and the photoconductor.

  Also, according to the present invention, the positioning member is formed such that the length along the width direction of the photoconductor is longer as it is closer to the driving roller, whereby the length of the positioning member is longer. Since the force for sandwiching and holding the photosensitive member becomes stronger, the effect of preventing meandering is further exhibited.

  Further, according to the present invention, the positioning member has an inclined surface in which the surface of the positioning member facing along the width direction of the photoconductor narrows the distance between the facing positioning members as it goes toward the drive roller. In other words, when the surface of the positioning member is tapered, a force for moving the photosensitive member toward the center acts, thereby preventing meandering.

1 is a schematic explanatory diagram illustrating an example of a configuration of a main part of an image forming apparatus according to a first embodiment of the present invention. It is explanatory drawing which shows the structure of the backing member and positioning member which comprise the said image forming apparatus. It is explanatory drawing by the side view which shows the positional relationship of the said backing part, the said positioning member, and exposure means. It is explanatory drawing which shows the pressing force which pinches | interposes a photoreceptor belt with the said backing part and the said positioning member. It is explanatory drawing which shows an example of the structure which presses the said positioning member with a spring member. It is explanatory drawing which shows the modification 1 of the structure which pinches | interposes a photoreceptor belt with the backing member and positioning member of 1st Embodiment. It is explanatory drawing which shows the modification 2 of a structure which pinches | interposes a photoreceptor belt with the backing member and positioning member of 1st Embodiment. It is explanatory drawing which shows the modification 3 of a structure which pinches | interposes a photoreceptor belt with the backing member and positioning member of 1st Embodiment. (A) is explanatory drawing which shows the structure of the backing part, positioning member, and charging means which comprise the image forming apparatus which concerns on 2nd Embodiment of this invention, (b) is AA sectional arrow directional view of (a). It is. (A) is explanatory drawing which shows the structure of the backing part, positioning member, and developing roller which comprise the image forming apparatus which concerns on 3rd Embodiment of this invention, (b) is a BB cross-sectional arrow directional view of (a). It is. It is a schematic explanatory drawing which shows the other structure which performs the image development process in the structure of the image forming apparatus which concerns on this invention. It is a schematic explanatory drawing which shows the modification of the other structure which performs the image development process in the structure of the image forming apparatus concerning this invention.

(First embodiment)
Hereinafter, embodiments for carrying out an image forming apparatus of the present invention will be described with reference to the drawings.
FIG. 1 is an example of an embodiment for carrying out the invention, and is a schematic explanatory diagram illustrating an example of a configuration of a main part of an image forming apparatus according to a first embodiment of the present invention.

  As shown in FIG. 1, the image forming apparatus 100 according to the first embodiment includes an endless belt-shaped photosensitive belt (photosensitive body) 1 on which an electrostatic latent image is formed, and a rotation for rotating the photosensitive belt 1. A driving roller 2, a driven roller 3 as a bridging roller for applying tension to the photosensitive belt 1, and a developer is supplied to the photosensitive belt 1 to develop an electrostatic latent image formed on the photosensitive belt 1. A plurality of developing devices 9 corresponding to each color to be applied, a charging unit 7 for applying a predetermined potential to the photosensitive belt 1, and an exposing unit 8 for forming an electrostatic latent image on the photosensitive belt 1. Thus, the configuration of the image forming apparatus according to the present invention is adopted as the configuration of the image forming apparatus that forms an image by electrophotography.

  First, a schematic configuration of the image forming apparatus 100 according to the first embodiment will be described.

  As shown in FIG. 1, the image forming apparatus 100 includes a photoreceptor belt 1, a driving roller 2 inside thereof, a driven roller 3 that bridges the photoreceptor belt 1 and is driven by the rotation of the photoreceptor belt 1, and a photoreceptor. A tension roller (bridging roller) 4 for pulling the belt 1 with a predetermined tension is provided. In addition, a transfer unit 6 is disposed at a position facing the driving roller 2, and in the vicinity of the photosensitive belt 1, for each color of Y (yellow), M (magenta), C (cyan), and K (black). In addition, a charging unit 7, an exposure unit 8, and a developing device 9 are arranged in parallel from the upstream side along the conveyance direction of the photosensitive belt 1.

  When the image data input signal is input, the image forming apparatus 100 rotates the driving roller 2 at a predetermined timing, conveys the photosensitive belt 1, and starts the development process.

  The charged surface of the photoreceptor belt charged with a predetermined charge amount over the entire axial direction of the bridging roller (width direction of the photoreceptor belt 1) by the charging unit 7 is transferred to the next step. Moving.

  Next, based on the input image data, the exposure unit 8 scans the surface of the photosensitive belt charged with light in the previous process, whereby an electrostatic latent image is formed on the photosensitive belt 1. .

  Thereafter, toner (an example of a developer) in the developing tank 92 is supplied onto the surface of the rotating photoreceptor belt by a developing roller (developing unit) 91 applied with a negative DC potential included in the developing device 9, and electrostatically The latent image is visualized (developed) by the toner according to the potential gap on the photosensitive drum 1.

  In addition, the paper (recording paper) to be imaged is conveyed in the direction of arrow P of the photosensitive belt 1 at the same timing, and the toner on the photosensitive belt 1 is transferred to the paper by the transfer unit 6 (corona charger (transfer means)). Is transcribed. The toner remaining on the photosensitive belt 1 is scraped off by the cleaning blade 5 and collected by a cleaner unit (not shown).

  The surface of the photoreceptor belt 1 from which the toner remaining by the cleaning blade 5 has been scraped off is neutralized as necessary by a neutralization device (static neutralization unit) (not shown) while moving to the charging unit 7.

  On the other hand, the paper on which the toner has been transferred undergoes a fixing process in which heat and pressure are applied to melt and fix the unfixed toner on the paper to the paper. Thereafter, the paper is discharged to a paper discharge tray (not shown), and a predetermined fixed image can be obtained on the paper.

Next, a characteristic configuration of the image forming apparatus 100 according to the first embodiment will be described with reference to the drawings.
FIG. 2 is an explanatory view showing the configuration of the backing member and the positioning member constituting the image forming apparatus according to the first embodiment, and FIG. 3 is a side view showing the positional relationship between the backing portion, the positioning member and the exposure means. FIG. 4 is an explanatory view showing a pressing force for sandwiching the photosensitive belt between the backing portion and the positioning member, and FIG. 5 is an explanatory view showing an example of a configuration in which the positioning member is pressed by a spring member. .

  As shown in FIGS. 1 and 2, the image forming apparatus 100 according to the first embodiment has a backing member 10 that is long along the width direction of the photosensitive belt at a position facing the exposure unit 8 through the photosensitive belt 1. And positioning members 11 for determining the distance between the exposure means 8 and the photosensitive belt 1 at both ends in the longitudinal direction of the backing member 10.

  The positioning member 11 is disposed so as to sandwich the end portion in the width direction of the photosensitive belt 1 with the backing member 10.

  As shown in FIG. 2, the backing member 10 has positioning members 11 attached to both ends of the photosensitive belt 1. The backing member 10 and the positioning member 11 are provided at positions facing the exposure means 8.

  As shown in FIG. 3, the exposure means 8 is provided with a positioning boss 12. By abutting the boss 12 and the positioning member 11, the distance between the backing member 10 and the exposure unit 8, that is, the distance between the photosensitive belt 1 and the exposure unit 8 is determined.

  As shown in FIG. 3, the positioning member 11 is attached so as to sandwich the photosensitive belt 1 with the backing member 10. By sandwiching the photoreceptor belt 1 between the backing member 10 and the positioning member 11, meandering and displacement of the photoreceptor belt 1 can be suppressed.

  In the first embodiment, the photosensitive belt 1 is sandwiched between the positioning member 11 and the backing member 10 of the exposure means provided corresponding to each color. However, the photoreceptor belt 1 is sandwiched more strongly near the drive roller 2. Such control is more effective.

  Further, since the photosensitive belt 1 is conveyed while being sandwiched, wear due to friction is inevitable at the position where the photosensitive belt 1 is sandwiched. Therefore, in order to reduce the influence of the friction, the positioning member 11 closer to the driving roller 2 has a stronger pressing force than the positioning members 11 of the exposure means 8 provided corresponding to each color are sandwiched by the same force. It is preferable to sandwich it with F (see FIG. 4). That is, assuming that the pressing force at the yellow position is Fy, the pressing force at the magenta position is Fm, and cyan and black are Fc and Fk, Fk ≧ Fc ≧ Fm ≧ Fy.

  As an example of a method of adjusting the pressing force F, the pressing force F may be adjusted by adjusting the tightening torque that presses the boss 12 with the mounting screw of the positioning member 11 (not shown) against the positioning member 11.

  Further, as shown in FIG. 5, a load spring 13 is attached to abut the exposure means 8, and the spring constant or deflection amount of the load spring 13 is adjusted corresponding to the exposure means 8 for each color. It is also possible to adjust the clamping force (pressing force F).

  Since it is configured as described above, according to the first embodiment, the image forming apparatus 100 is configured to be long along the width direction of the photosensitive belt 1 at a position facing the exposure unit 8 via the photosensitive belt 1. A backing member 10 is provided, and a positioning member 11 for determining a separation distance between the exposure means 8 and the photosensitive belt 1 is provided at both ends of the backing member 10 in the longitudinal direction. By arranging the end portions in the direction so as to be sandwiched between the backing member 10, the distance between the photoreceptor belt 1 and the exposure means 8 is accurately positioned, and the photoreceptor belt 1 is sandwiched between both ends of the photoreceptor belt 1. Can be stabilized and the meandering of the photosensitive belt 1 can be prevented.

(Modification 1)
Next, Modification 1 of the first embodiment will be described with reference to the drawings.
FIG. 6 is an explanatory view showing a first modification example in which the photosensitive belt is sandwiched between the backing member and the positioning member of the first embodiment.

  As a modified example of the configuration in which the photoreceptor belt 1 is sandwiched between the backing member 10 and the positioning member 11 according to the first embodiment, the modified example 1 is between the positioning member 11 and the photoreceptor belt 1 as shown in FIG. A wear-resistant sliding member 14 is disposed on the surface.

  Since it comprised in this way, according to the modification 1, the influence by the friction of the photosensitive belt 1 can be reduced.

  It is also possible to adjust the force for sandwiching the photoreceptor belt 1 by changing the thickness t of the sliding member 14 for each color.

(Modification 2)
Next, Modification 2 of the first embodiment will be described with reference to the drawings.
FIG. 7 is an explanatory view showing a second modification example in which the photosensitive belt is sandwiched between the backing member and the positioning member of the first embodiment.

In the second modification, as shown in FIG. 7, in the positioning members 111Y, 111M, 111C, and 111K provided for each color, the direction perpendicular to the conveying direction of the photosensitive belt 1 (the width direction of the photosensitive belt 1). The length along the line is longer as the distance from the drive roller 2 increases.
That is, the positioning members 111Y, 111M, 111C, and 111K are formed so as to become longer gradually from the upstream side toward the downstream side in the conveyance direction of the photosensitive belt 1.

  With this configuration, according to the second modification, the longer the length of the positioning member 111, the stronger the force to sandwich and hold the photosensitive belt 1, which is effective in preventing meandering of the photosensitive belt 1.

(Modification 3)
Next, Modification 3 of the first embodiment will be described with reference to the drawings.
FIG. 8 is an explanatory view showing a third modification example in which the photosensitive belt is sandwiched between the backing member and the positioning member of the first embodiment.

  As shown in FIG. 8, in the third modification example, in addition to the configuration of the second modification example described above, the positioning member 211 (211Y, 211M, 211C, 211K) provided for each color is used. The inclined surfaces 211Ya, 211Ma, 211Ca, and 211Ka are formed so that the surfaces facing the width direction become narrower as the distance between the facing positioning members becomes closer to the drive roller 2 side.

  Specifically, for example, the inclined surface 211Ka of the positioning member 211K is formed so that the end portion Ka1 close to the drive roller 2 has a tapered shape.

  With this configuration, according to the third modification, the photosensitive belt 1 is conveyed to the drive roller 2 side by the shapes of the inclined surfaces 211Ya, 211Ma, 211Ca, and 211Ka of the positioning members 211Y, 211M, 211C, and 211K. Accordingly, the force to move the photosensitive belt 1 to the center acts, so that the meandering of the photosensitive belt 1 can be prevented.

(Second Embodiment)
Next, a second embodiment of the image forming apparatus of the present invention will be described with reference to the drawings.
FIG. 9A is an explanatory view showing the configuration of the backing portion, the positioning member, and the charging means constituting the image forming apparatus according to the second embodiment of the present invention, and FIG. 9B is an AA sectional arrow of FIG. FIG.

  In the second embodiment, as shown in FIGS. 9A and 9B, an exposure unit having a configuration in which the photosensitive belt 1 is sandwiched between the backing member 10 and the positioning member 11 in the image forming apparatus 100 of the first embodiment. Instead of 8, the charging means 7 is positioned.

  Specifically, in the second embodiment, as shown in FIG. 9A, a long backing member along the width direction of the photosensitive belt 1 at a position facing the charging unit 7 via the photosensitive belt 1. 10 and positioning members 311 for determining the separation distance between the charging means 7 and the photosensitive belt 1 are provided at both longitudinal ends of the backing member 10. In addition, holding members 15 and 15 are provided to hold the charging unit 7 at both longitudinal ends 7 a and 7 b along the width direction of the photosensitive belt 1, and a positioning boss 15 a provided on the holding member 15 is provided by the positioning member 311. Positioned and held.

  Since it comprised as mentioned above, according to 2nd Embodiment, the photoreceptor belt 1 is pinched | interposed by the positioning member 311 and the backing member 10 by putting the holding member 15 into contact with the positioning member 311. Therefore, the meandering and the deviation of the photosensitive belt 1 can be suppressed, and the distance between the photosensitive belt 1 and the charging unit 7 can be accurately positioned.

(Third embodiment)
Next, a third embodiment of the image forming apparatus of the present invention will be described with reference to the drawings.
FIG. 10A is an explanatory view showing the configuration of a backing portion, a positioning member, and a developing roller constituting an image forming apparatus according to the third embodiment of the present invention, and FIG. FIG.

  In the third embodiment, as shown in FIGS. 10A and 10B, an exposure unit having a configuration in which the photosensitive belt 1 is sandwiched between the backing member 10 and the positioning member 11 in the image forming apparatus 100 of the first embodiment. In place of FIG. 8, the developing roller 91 is positioned.

In the image forming apparatus 100, when developing without contact, it is important to manage the gap between the photosensitive belt 1 and the developing roller 91. Therefore, if the photoreceptor belt 1 is loose, the gap is not stable. Therefore, the backing member 10 is brought into contact with the inside of the photoreceptor belt 1 and rubbed to cause the photoreceptor belt 1 and the backing member 10 to be rubbed. The positional relationship is always stable.
That is, if the positional relationship between the developing roller 91 and the backing member 10 is determined, the gap between the photosensitive belt 1 and the developing roller 91 is stabilized.

  Specifically, in the third embodiment, as shown in FIG. 10A, a long backing member along the width direction of the photosensitive belt 1 at a position facing the developing roller 91 via the photosensitive belt 1. 10 and positioning members 411 for determining the distance between the developing roller 91 and the photosensitive belt 1 are provided at both ends in the longitudinal direction of the backing member 10. Further, positioning rollers 16 and 16 are provided to hold the developing roller 91 at both longitudinal ends 91a and 91b along the width direction of the photosensitive belt 1, and the positioning roller 16 is brought into contact with the positioning member 411 to position the developing roller 91. It is what you do.

  With the above configuration, according to the third embodiment, the photosensitive belt 1 is sandwiched between the positioning member 411 and the backing member 10 by bringing the positioning roller 16 into contact with the positioning member 311. Therefore, it is possible to suppress the meandering and deviation of the photosensitive belt 1, and to accurately position the distance between the photosensitive belt 1 and the developing roller 91.

  Note that the image forming apparatus 100 in the embodiment and the modification described above includes the charging unit 7 and the exposure unit 8 for each color, that is, each color, but the present invention can be applied to other image forming apparatuses. .

  FIG. 11 is a schematic explanatory view showing another configuration for performing the developing process in the configuration of the image forming apparatus according to the present invention. FIG. 12 is a modified example of the other configuration for performing the developing process in the configuration of the image forming apparatus according to the present invention. It is a schematic explanatory drawing shown.

  Specifically, for example, as shown in FIG. 11, the present invention provides an image forming apparatus 200 in which four passes, that is, one charging unit 7 and one exposure unit 8 are mounted, and the developing process is performed by four rotations. Can also be adapted.

  Further, as a modification, in order to provide a device for performing a smaller development process, as shown in FIG. 12, an exposure means 8 is mounted inside (back side) of the photosensitive belt 1 so that an electrostatic latent image is formed. The present invention can also be applied to an image forming apparatus 300 that employs a so-called back exposure method.

  As described above, the present invention is not limited to the above-described embodiments and modifications, and various modifications can be made within the scope of the claims. That is, embodiments obtained by combining technical means appropriately changed within the scope not departing from the gist of the present invention are also included in the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Photoconductor belt 2 Drive roller 3 Driven roller 7 Charging means 7a, 7b Both ends in the longitudinal direction 8 Exposure means 9 Developing device 10 Backing member 11, 111, 111Y, 111M, 111C, 111K,
211Y, 211M, 211C, 211K, 311, 411 Positioning member 14 Sliding member 15 Holding member 16 Positioning roller 91 Developing roller 100, 200, 300 Image forming apparatus 211Ya, 211Ma, 211Ca, 211Ka Inclined surface

Claims (8)

An endless belt-shaped photoconductor on which an electrostatic latent image is formed, a driving roller for rotating the photoconductor, a bridging roller for applying tension to the photoconductor, and a developer supplied to the photoconductor A plurality of developing devices corresponding to respective colors for developing the electrostatic latent image formed on the photosensitive member, charging means for applying a predetermined potential to the photosensitive member, and an electrostatic latent image on the photosensitive member. An image forming apparatus that forms an image by an electrophotographic method,
A long backing member is provided along the width direction of the photoconductor at a position facing a developing roller constituting the developing device via the photoconductor,
At both ends in the longitudinal direction of the backing member, a positioning member for determining a separation distance between the developing roller and the photoconductor is provided.
The image forming apparatus, wherein the positioning member is disposed so as to sandwich an end portion in the width direction of the photoconductor with the backing member. An endless belt-shaped photoconductor on which an electrostatic latent image is formed, a driving roller for rotating the photoconductor, a bridging roller for applying tension to the photoconductor, and a developer supplied to the photoconductor A plurality of developing devices corresponding to respective colors for developing the electrostatic latent image formed on the photosensitive member, charging means for applying a predetermined potential to the photosensitive member, and an electrostatic latent image on the photosensitive member. An image forming apparatus that forms an image by an electrophotographic method,
A plurality of the exposure means are provided corresponding to the plurality of developing devices,
Provided with a long backing member along the width direction of the photoconductor at a position facing the exposure means via the photoconductor,
At both ends in the longitudinal direction of the backing member, a positioning member for determining a separation distance between the exposure means and the photoconductor,
The image forming apparatus, wherein the positioning member is disposed so as to sandwich an end portion in the width direction of the photoconductor with the backing member. An endless belt-shaped photoconductor on which an electrostatic latent image is formed, a driving roller for rotating the photoconductor, a bridging roller for applying tension to the photoconductor, and a developer supplied to the photoconductor A plurality of developing devices corresponding to respective colors for developing the electrostatic latent image formed on the photosensitive member, charging means for applying a predetermined potential to the photosensitive member, and an electrostatic latent image on the photosensitive member. An image forming apparatus that forms an image by an electrophotographic method,
A plurality of the charging means are provided corresponding to the plurality of developing devices,
Provided with a long backing member along the width direction of the photoconductor at a position facing the charging means via the photoconductor,
At both ends in the longitudinal direction of the backing member, a positioning member for determining a separation distance between the charging unit and the photosensitive member is provided.
The image forming apparatus, wherein the positioning member is disposed so as to sandwich an end portion in the width direction of the photoconductor with the backing member. A pressing member that presses the positioning member in the direction of the backing member;
The image forming apparatus according to claim 3, wherein the pressing force of the positioning member is increased as it is closer to the driving roller.   5. The pressing force of the positioning member is adjusted by a force that abuts the developing roller, the exposure unit, or the charging unit against the positioning member. 6. Image forming apparatus.   The image forming apparatus according to claim 1, wherein a sliding member is disposed between the positioning member and the photosensitive member.   7. The positioning member according to claim 1, wherein the positioning member is formed such that a length along the width direction of the photosensitive member is longer as it is closer to the driving roller. 8. The image forming apparatus described in 1.   The positioning member is formed such that a surface of the positioning member facing along the width direction of the photosensitive member is an inclined surface in which an interval between the facing positioning members becomes narrower toward the drive roller side. The image forming apparatus according to any one of claims 1 to 7.