JP2008083614A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus where space saving and cost reduction can be attained by reducing the number of components of a cleaning means. <P>SOLUTION: The image forming apparatus 10 includes: image carriers 14a to 14d; charging means 16a to 16d for charging the image carriers 14a to 14d; exposure means 18a to 18d for forming latent images on the surfaces of the image carries 14a to 14d; development means 20a to 20d for developing the latent images to toner images; a transfer means 24 with an endless annular transfer body 26 arranged so as to be in contact with the image carriers 14a to 14d and used for directly or indirectly transferring the toner images to a recording medium; a tension roller 38 for applying tension to the transfer body 26; and a cleaning means 40 for cleaning residual toner on the surface of the transfer body 26. The tension roller 38 also has the function that a cleaning means 40 has. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile, or a composite machine using an electrophotographic method, and in particular, image formation in which a toner image is transferred to a recording medium such as paper via a transfer belt. Relates to the device.

The conventional color image forming apparatus as the background of the present invention includes, for example, an image unit in which toners of different colors are accommodated and arranged in a tandem manner, and runs around the arrangement direction of the image unit. An endless intermediate transfer belt on which a plurality of color toner images formed thereon are sequentially superimposed and transferred to form a color toner image, and when the circumference of the intermediate transfer belt becomes longer, Installed near the upstream side of the belt support roller, placed at a position opposite the tension roller for applying a constant tension to the intermediate transfer belt and the belt support roller, and presses the roller via the intermediate transfer belt to Some have a secondary transfer roller that collectively transfers a composite toner image formed on a transfer belt onto a sheet (for example, see Patent Document 1).
According to this color image forming apparatus, the tension roller is installed in the vicinity of the upstream side of the roller located in the vicinity of the upstream side of the image forming unit with respect to the traveling direction of the intermediate transfer belt. Can be formed at the installation position of the image forming unit and the transfer position of the toner image onto the recording medium.

  However, in this color image forming apparatus, a tension roller is arranged inside the closed-loop intermediate transfer belt, and tension is applied to the intermediate transfer belt from the inside of the intermediate transfer belt. For this reason, in this color image forming apparatus, the intermediate transfer belt is curved outward, and the proportion of the intermediate transfer belt in the image forming apparatus main body increases, and there is still a problem in order to save space. there were.

Therefore, in order to solve such a problem, for example, a tension roller is disposed outside an endless intermediate transfer belt that is looped around a plurality of rollers, and the intermediate transfer belt is arranged from the outside of the intermediate transfer belt. There are a belt device configured to apply tension to the belt and an image forming apparatus using the belt device (see, for example, Patent Document 2).
In this image forming apparatus, the tension is applied by the tension roller, so that the loop-shaped intermediate transfer belt is curved inward, so that space saving is achieved as compared with the one disclosed in Patent Document 1 described above. It is possible.

JP 2001-356555 A Japanese Patent Laid-Open No. 2004-258067

However, in this belt device and an image forming apparatus using the belt device, a belt cleaning member including a cleaning recovery roller, a fur brush, a cleaning blade, and the like is provided on the upstream side of the tension roller and outside the intermediate transfer belt. . In this case, the number of parts of the belt cleaning member is large, resulting in a problem in cost reduction. Further, due to the large number of parts, the space for arranging the belt cleaning member in the main body of the image forming apparatus still has a problem.
On the other hand, further space saving and downsizing of the image forming apparatus are demanded, and accordingly, further downsizing of the image forming unit is required. That is, also in the belt cleaning unit, it is desired to reduce the size of components or reduce the number of components as much as possible.

  Therefore, a main object of the present invention is to provide an image forming apparatus capable of saving space and reducing costs by reducing the number of parts of the cleaning means.

According to a first aspect of the present invention, there is provided an image carrier, a charging unit for charging the image carrier, an exposure unit for forming a latent image on the surface of the image carrier, and a developing unit for developing the latent image into a toner image. A transfer means having an endless annular transfer body that is disposed so as to be in contact with the image carrier and is used to transfer a toner image directly or indirectly to a recording medium; and a tension for applying tension to the transfer body. An image forming apparatus including a roller and a cleaning unit that cleans residual toner on the surface of a transfer body, wherein the tension roller has a function of a cleaning unit.
In the present invention according to claim 1, since the tension roller also has the function of the cleaning means, it is possible to reduce the number of parts, thereby saving space and reducing costs.
The present invention according to claim 2 is an invention dependent on the invention according to claim 1, wherein the cleaning means includes a cleaning recovery roller for cleaning the residual toner on the surface of the transfer body, and the tension roller includes the cleaning recovery The image forming apparatus is also used as a roller.
In the present invention according to claim 2, since the tension roller is also used as a cleaning recovery roller, the number of parts of the cleaning means can be reduced by the amount corresponding to the cleaning recovery roller. As a result, space saving and cost reduction can be achieved.
The present invention according to claim 3 is an invention dependent on the invention according to claim 1 or claim 2, wherein the tension roller is arranged outside the transfer body, and the transfer body faces from the outside to the inside of the transfer body. The image forming apparatus is configured so that tension is applied to the image forming apparatus.
In the present invention according to claim 3, the tension roller is arranged outside the endless annular transfer body, and the tension is applied to the transfer body from the outside to the inside of the transfer body. The transfer body at the applied site is curved inward. Therefore, in the present invention according to claim 3, in addition to the effect of the invention according to claim 1 or 2, the space around the transfer body can be further saved.
The present invention according to claim 4 is an invention dependent on the invention according to any one of claims 1 to 3, wherein the discharge direction of the residual toner collected by the cleaning means is the same as the pressing direction of the tension roller. An image forming apparatus having a direction.
In the present invention according to claim 4, in addition to the effect of the invention according to any one of claims 1 to 3, the discharge direction of the residual toner collected by the cleaning means is the same as the pressing direction of the tension roller. Therefore, even if the cleaning means vibrates due to an external force or the like, for example, residual toner is smoothly discharged along the discharge direction.
The present invention is an invention dependent on the invention according to any one of claims 1 to 4, wherein the tension roller includes a conductive roller, and a cleaning blade is brought into contact with the roller, The toner remaining on the transfer member attached to the roller may be cleaned.
The invention of the present application is an invention dependent on the invention according to any one of claims 1 to 5, wherein the transfer means is in contact with the image carrier and moves in a loop while the toner image on the surface thereof. Intermediate transfer belt to which toner is transferred, primary transfer means for primary transfer of the toner image to the intermediate transfer belt, and secondary transfer for secondary transfer of the toner image transferred to the surface of the intermediate transfer belt to the surface of the recording medium The image forming apparatus may include a recording medium conveying unit that conveys the recording medium to the toner image carrying surface side of the intermediate transfer belt in the secondary transfer unit. In this case, the toner image is transferred to the recording medium indirectly via the intermediate transfer belt.
Furthermore, the present invention is an invention dependent on any one of the first to fifth aspects of the present invention, wherein the transfer means is in contact with the image carrier and moves in a loop while the toner image on the surface thereof. An intermediate transfer belt to which the toner image is transferred, a recording medium conveyance means for conveying a recording medium to the toner image carrying surface side of the intermediate transfer belt, and a primary transfer means for primary transfer of the toner image to the intermediate transfer belt, The toner image may be an image forming apparatus in which the toner image is directly transferred to a recording medium between the intermediate transfer belt and the image carrier.

  According to the image forming apparatus of the present invention, it is possible to obtain an image forming apparatus capable of saving space and reducing costs by reducing the number of parts of the cleaning means.

  The above object, other objects, features, and advantages of the present invention will become more apparent from the following description of the best mode for carrying out the invention with reference to the drawings.

FIG. 1 is a schematic configuration diagram illustrating an overall configuration of an example of an embodiment according to the present invention, and FIG. 2 is a conceptual configuration diagram illustrating a main part of the image forming apparatus illustrated in FIG. 1.
In this embodiment, as an example of an image forming apparatus, an image forming apparatus such as a so-called tandem type color electrophotographic copying machine of an intermediate transfer system will be described below.
The image forming apparatus 10 includes, for example, four image forming units 12A, 12B, 12C, and 12D that form toner images of, for example, yellow, magenta, cyan, and black color components by electrophotography. Each of the four image forming units 12A, 12B, 12C, and 12D includes, for example, drum-shaped photoreceptors 14a, 14b, 14c, and 14d as image carriers that form the image bearing means for each color.

  Around the photoreceptors 14a, 14b, 14c and 14d, for example, charging devices 16a, 16b, 16c and 16d as charging means for charging the photoreceptors 14a, 14b, 14c and 14d, and the photoreceptors 14a, 14a, 14d, respectively. For example, exposure devices 18a, 18b, 18c and 18d as exposure means for forming latent images of the respective colors on 14b, 14c and 14d, and the latent images formed on the photoreceptors 14a, 14b, 14c and 14d are used as toner images. Developing devices 20a, 20b, 20c and 20d as developing means for developing, and photoreceptor cleaning devices 22a, 22b, 22c as image carrier cleaning means for cleaning the toner on the respective photoreceptors 14a, 14b, 14c and 14d, and 22d.

Under the photoreceptors 14a, 14b, 14c and 14d, transfer means 24 for transferring a toner image onto a recording sheet (not shown) as a recording medium is disposed.
That is, the transfer unit 24 includes an intermediate transfer belt 26 formed of, for example, a sheet-like endless annular belt as a transfer body onto which the toner images of the respective colors developed by the developing devices 20a, 20b, 20c and 20d are transferred. . Inside the intermediate transfer belt 26, for example, primary transfer rollers 28a, 28b, 28c, 28d as first transfer means, a driving roller 30, a driven roller 32, and a secondary transfer roller as second transfer means, for example. A secondary transfer counter roller 36 that is disposed to face 34 is disposed.

  A tension roller 38 is disposed outside the endless annular intermediate transfer belt 26. The tension roller 38 is disposed at the intermediate portion between the driven roller 32 and the secondary transfer roller 34 and on the downstream side of the secondary transfer roller 34. The tension roller 38 is configured to appropriately apply a predetermined tension to the intermediate transfer belt 26 from the outer side to the inner side of the intermediate transfer belt 26. That is, the intermediate transfer belt 26 is stretched by a tension roller 38 while maintaining constant tension on roller members such as the primary transfer rollers 28a, 28b, 28c, and 28d, the driving roller 30, the driven roller 32, and the secondary transfer roller 34. Is provided. In this case, the intermediate transfer belt 26 is bent inward at a portion to which tension is applied by the tension roller 38.

The intermediate transfer belt 24 is driven to rotate at a predetermined rotation speed when the driving roller 28 is driven by a driving motor (not shown). Therefore, the toner image is transferred to the surface of the intermediate transfer belt 26 while rotating around the intermediate transfer belt 26 in contact with the photoreceptors 14a, 14b, 14c and 14d by driving the driving roller 30.
In other words, the primary transfer rollers 28a, 28b, 28c, and 28d are arranged to face the photoconductors 14a, 14b, 14c, and 14d, respectively, and a voltage having a polarity opposite to the charging polarity of the toner is applied to the photoconductor 14a. , 14b, 14c, and 14d are electrostatically attracted to the intermediate transfer belt 26 and primarily transferred.

In this embodiment, in particular, the tension roller 38 also has a function as a cleaning unit that cleans residual toner on the intermediate transfer belt 26.
That is, the cleaning device 40 as the cleaning means includes a housing 40A as shown in FIG. 2, for example, and a tension roller 38 having a function as a cleaning recovery roller is disposed in the housing 40A. The tension roller 38 is also used as a cleaning recovery roller, and recovers and cleans residual toner on the surface of the intermediate transfer belt 26.

The tension roller 38 (also used as a cleaning recovery roller) includes, for example, a conductive roller 42. The roller 42 is formed of a conductive rubber roller, a metal roller, or the like. As the rubber roller, for example, a roller having a conductive foamed EPDM rubber layer whose electric resistance is adjusted to a predetermined value is used. Further, as the metal roller, a roller made of sulfur composite free-cutting steel such as SUM22L, SUM21, SUM24L or the like is used.
In the vicinity of the roller 42, for example, a rubber cleaning blade 44 is disposed. The cleaning blade 44 is supported on the housing 40A by a bracket 46 having an L-shaped cross section, for example. By bringing the cleaning blade 44 into contact with the roller 42, the residual toner of the intermediate transfer belt 26 collected by electrostatic adhesion to the roller 42 is cleaned. The roller 42 is urged and supported by the housing 40A by an urging means 46 such as a spring for pressing the roller 42 against the surface of the intermediate transfer belt 26 with a constant pressing force.

In addition, in the housing 40A, a toner screw (not shown) of a toner conveying unit that conveys the residual toner that has been removed from the surface of the roller 42 by the cleaning blade 44 and conveyed in the discharging direction is disposed. In this embodiment, the discharge direction of the residual toner collected by the cleaning blade 44 from the surface of the roller 42 is arranged in the same direction as the pressing direction of the tension roller 38.
The conveying screw (not shown) is provided with a spiral conveying blade around the rotation axis and is rotatably supported in the housing 40A. Residual toner scraped off from the surface of the roller 42 by the cleaning blade 44 is sequentially transported in the discharge direction by rotation of a transport screw (not shown), and a toner discharge port 50 provided on the bottom surface of the housing 40A. Is discharged to the outside of the housing 40A and stored, for example, in a waste bottle (not shown).

  On the other hand, the intermediate transfer belt 26 is sandwiched between the secondary transfer roller 34 and the secondary transfer counter roller 36, and the intermediate transfer belt 26 passes between the secondary transfer roller 34 and the secondary transfer counter roller 36. In synchronization with this, the recording paper is supplied to the toner image carrying surface side of the intermediate transfer belt 26. In this case, the recording paper is pulled out from the paper feed cassette 60 one by one, and further fed out to the recording paper transport path 64 by the recording paper transport roller 62. The recording sheet is conveyed / supplied between the secondary transfer roller 34 and the secondary transfer counter roller 36 via a recording sheet conveyance path 64 and a timing roller (not shown). At this time, a voltage having a polarity opposite to the charging polarity of the toner is applied to the secondary transfer roller 34, so that the contact surface of the recording paper that is in contact with the toner image carrying surface side of the intermediate transfer belt 26 has no toner. The image is secondarily transferred. In this case, the toner is positively charged, whereas the secondary transfer roller 34 is applied with a negative bias.

  Further, the recording sheet on which the toner image is secondarily transferred is separated from the intermediate transfer belt 26 by the separation function of the secondary transfer roller 34 and the secondary transfer counter roller 36, and the transfer belt 66 serves as, for example, heat as a fixing unit. It is conveyed to the fixing device 68. The unfixed toner image on the recording sheet conveyed to the heat fixing device 68 is subjected to a toner image fixing process by heating and then conveyed toward a predetermined paper discharge tray (not shown).

  In this embodiment, since the tension roller 38 also has the function of the cleaning device 40, the number of parts can be reduced, thereby saving space and reducing costs. That is, since the tension roller 38 also serves as the roller 42 forming the cleaning recovery roller, the number of parts constituting the cleaning device 40 can be reduced by at least the roller 42. Therefore, it is possible to save the space for the image forming units 12A, 12B, 12C, 12D and the transfer unit 24 in the main body of the image forming apparatus, and it is possible to reduce the cost associated therewith.

  Further, in this embodiment, the tension roller 38 is positioned outside the endless annular intermediate transfer belt 26, and a predetermined tension is appropriately applied to the intermediate transfer belt 26 from the outside to the inside of the intermediate transfer belt 26. Therefore, the intermediate transfer belt 26 at the portion where the tension is applied is curved inward. Accordingly, the space around the intermediate transfer belt 26 and the transfer means 24 can be further saved.

  Further, in this embodiment, the discharge direction of the residual toner on the intermediate transfer belt 26 collected by the cleaning device 40 via the roller 42 forming the cleaning collection roller is the rotation direction of the tension roller 38 (FIG. 2). Therefore, even if the cleaning device 40 is moved by an external force such as expansion / contraction due to an environmental change of the intermediate transfer belt 26, for example, the residual toner is smoothly discharged in the discharge direction. Are to be discharged along.

  In the above-described embodiment, the transfer unit 24 sequentially contacts the plurality of photoconductors 14a, 14b, 14c, and 14d and moves in a loop shape, and the intermediate transfer belt onto which the toner image is transferred to the surface. 26, primary transfer rollers 28a, 28b, 28c, 28d for primary transfer of the toner image to the intermediate transfer belt 26, and the toner image transferred to the surface of the intermediate transfer belt 26 are secondarily transferred to the surface of the recording paper. A recording sheet for conveying the recording sheet to the surface of the intermediate transfer belt 26 (on the toner image carrying surface side) between the secondary transfer roller 34, the secondary transfer counter roller 36, and the secondary transfer roller 34 and the secondary transfer counter roller 36. And a recording medium conveying unit including a conveying roller 64 and a recording paper conveying path 64, and the toner image is transferred to the recording paper indirectly via the intermediate transfer belt 26. The image forming apparatus 10 is not limited thereto. For example, the transfer unit 24 contacts the photoconductors 14a, 14b, 14c, and 14d and moves in a loop shape, and a toner image is transferred to the surface thereof. The intermediate transfer belt 26, the primary transfer rollers 28 a, 28 b, 28 c, 28 d that primarily transfer the toner image to the intermediate transfer belt 26, and the recording paper transported to the toner image carrying surface side of the intermediate transfer belt 26. The image forming apparatus may include a medium conveying unit, and the toner image may be directly transferred onto a recording sheet between the intermediate transfer belt 26 and the photoreceptors 14a, 14b, 14c, and 14d.

  In the image forming apparatus 10 of the above-described embodiment, the image forming unit includes a plurality of developing devices 20a, 20b, 20c, and 20d and a plurality of photosensitive members 14a, 14b, 14c, and 14d. Instead, for example, the image forming apparatus may include an image forming unit including one developing device 20a and one photoconductor 14a.

It is a schematic block diagram which shows the whole structure of an example of embodiment concerning this invention. FIG. 2 is a conceptual configuration diagram illustrating a main part of the image forming apparatus illustrated in FIG. 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 12A, 12B, 12C, 12D Image forming unit 14a, 14b, 14c, 14d Photoconductor 16a, 16b, 16c, 16d Charging device 18a, 18b, 18c, 18d Exposure device 20a, 20b, 20c, 20d Developing device 22a, 22b, 22c, 22d Photoconductor cleaning device 24 Transfer means 26 Intermediate transfer belt 28a, 28b, 28c, 28d Primary transfer roller 30 Drive roller 32 Driven roller 34 Secondary transfer roller 36 Secondary transfer roller counter roller 38 Tension roller DESCRIPTION OF SYMBOLS 40 Cleaning apparatus 40A Housing 42 Roller 44 Cleaning blade 46 Bracket 48 Energizing means 50 Toner discharge port 60 Paper feed cassette 62 Recording paper conveyance roller 64 Recording paper conveyance path 66 Transfer belt 68 Thermal fixing device

Claims (4)

Image carrier,
Charging means for charging the image carrier,
Exposure means for forming a latent image on the surface of the image carrier;
Developing means for developing the latent image into a toner image;
Transfer means having an endless annular transfer body that is disposed so as to be in contact with the image carrier and is used to transfer the toner image directly or indirectly to a recording medium;
An image forming apparatus including a tension roller for applying tension to the transfer body, and a cleaning unit for cleaning residual toner on the surface of the transfer body,
The image forming apparatus, wherein the tension roller also has a function of the cleaning unit.   The image according to claim 1, wherein the cleaning unit includes a cleaning recovery roller that cleans residual toner on the surface of the transfer member, and the tension roller is also used as the cleaning recovery roller. Forming equipment.   2. The tension roller according to claim 1, wherein the tension roller is disposed outside the transfer body, and is configured to apply tension to the transfer body from the outside to the inside of the transfer body. Item 3. The image forming apparatus according to Item 2.   The image forming apparatus according to claim 1, wherein a discharge direction of the residual toner collected by the cleaning unit is the same as a pressing direction of the tension roller.

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