JP2007163741A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress soil of a belt surface due to toner crowd from a development roller in a tandem type image forming apparatus. <P>SOLUTION: The image forming apparatus is vertical to an intermediate transfer belt 14. The apparatus is at the side of a first image formation unit 48a rather than a straight line L if the straight line passing a side end of a second image formation unit 48b of a development roller 74a in the first image formation unit 48a is L. The end of a cleaning device 60b, a part of the second image formation unit 48b, is inserted between the development roller 74a of the first image formation unit 48a and the intermediate transfer belt 14, and a scattering suppression part 80 is constituded. The toner crowd is suppressed from scattering up to the intermediate transfer belt 14 with the scattering suppression part 80. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as a printer, a facsimile machine, and a copying machine.

  A tandem method is known as one of the methods of this type of image forming apparatus. In this tandem system, for example, four image forming units are arranged in parallel around the belt to form a color image. While this tandem method can obtain high productivity, the apparatus is increased in size because four image forming units are arranged.

  Therefore, for example, in the inventions described in Patent Documents 1 and 2, in a tandem type image forming apparatus, a cleaning device of one image forming unit is overlapped with a developing device of another image forming unit in the vertical direction to reduce the size of the device. We are trying to make it.

JP 2002-148892 A JP 2004-162807 A

  However, in the above two conventional examples, the distance between the developing roll constituting the developing device and the belt is close, and the surface of the belt is caused by the cloudy toner (hereinafter referred to as toner cloud) generated from the developing roll. There was a risk of contamination and image quality degradation.

  An object of the present invention is to suppress contamination of a belt surface due to a toner cloud from a developing roll in a tandem type image forming apparatus.

  The first feature of the present invention includes a belt and a plurality of image forming units arranged in parallel along the belt, and each image forming unit includes at least a developing roll, and the belt includes The image forming unit is located on one image forming unit side with respect to a straight line passing through the other image forming unit side end of the developing roll in one image forming unit, and between the developing roll of the one image forming unit and the belt. The image forming apparatus has a part of another image forming unit in between.

  Preferably, each of the image forming units further includes a photoconductor disposed to face the belt, and a portion of the developing roll closest to the belt is separated from the belt by a radius of the photoconductor.

  Preferably, each image forming unit has a cleaning device that cleans the toner on the photosensitive member, and a portion that enters one image forming unit side from the straight line is at least a part of the cleaning device. is there.

  Preferably, the belt is arranged obliquely with respect to the horizontal direction.

  The second feature of the present invention is that it has a belt and a plurality of image forming units arranged in parallel along the belt, and each image forming unit has at least a developing roll and has one image. In the image forming apparatus, the other image forming unit is provided with a scattering suppression unit that suppresses scattering of the toner cloud generated from the developing roll of the forming unit to the belt side.

  Preferably, the scattering prevention unit is on one image forming unit side with respect to a straight line that is perpendicular to the belt and passes through the other image forming unit side end of the developing roll in one image forming unit. It is provided so as to enter between the developing roll of one image forming unit and the belt.

  Preferably, each image forming unit has a cleaning device that cleans the toner on the photoconductor, and the scattering prevention unit is provided in a cleaning device of another image forming unit.

  The belt may be an intermediate transfer belt or a conveyance belt that conveys a sheet.

Next, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows an image forming apparatus 10 according to an embodiment of the present invention. The image forming apparatus 10 includes an image forming apparatus main body 12, and an intermediate transfer belt 14 is disposed in the image forming apparatus main body 12. For example, four image forming units 16 are arranged in parallel to the intermediate transfer belt 14, and the image forming apparatus 10 is a so-called tandem system. The image forming unit 16 forms toner images of respective colors of yellow, magenta, cyan, and black on the intermediate belt 14.

  A sheet supply device 18 is provided below the image forming apparatus main body 12. The sheet supply device 18 includes a sheet supply cassette 20 on which sheets are stacked, a pickup roll 22 that picks up the sheets stacked on the sheet supply cassette 20, and a feed roll 24 and a retard roll 26 that send out the sheets while rolling them. . The sheet supply cassette 20 is detachably attached to the image forming apparatus main body 12 so that the sheet supply cassette 20 can be pulled out in the front direction in the figure, and sheets as transfer objects such as plain paper and OHP sheets are stacked and stored. ing.

  Near one end of the image forming apparatus main body 12 (near the left end in the figure), a sheet supply path 28 is provided substantially along the vertical direction. In the sheet supply path 28, a transport roll 29, a resist roll 30, a secondary transfer roll 32, a fixing device 34 and a discharge roll 36 are provided. The registration roll 30 temporarily stops the sheet sent to the sheet supply path 28 and sends it to the secondary transfer roll 32 at a timing. The fixing device 34 includes a heating roll 34a and a pressure roll 34b, and fixes the toner image on the sheet by applying heat and pressure to the sheet passing between the heating roll 34a and the pressure roll 34b. ing.

  A discharge tray section 38 is provided on the upper part of the image forming apparatus main body 12. The sheet having the toner image fixed thereon is discharged onto the discharge tray portion 38 by the discharge roll 36 described above, and is stacked on the discharge tray portion 38. Accordingly, the sheets in the sheet supply cassette 20 are sequentially discharged to the discharge tray unit 38 through a C-shaped path.

  For example, four toner bottles 40 are provided on the other end side (right end side in the figure) of the image forming apparatus main body 12. The toner bottle 40 contains yellow, magenta, cyan, and black toners, and supplies the toner to the image forming unit 16 via a toner supply path (not shown).

  The intermediate transfer belt 14 is supported by a plurality of conveying rolls 42, and the belt surface on which the above-described image forming unit 16 is provided is inclined with respect to the horizontal direction. One of the transport rolls 42 constitutes a backup roll for the secondary transfer roll 32. An intermediate belt cleaning device 44 is disposed in the vicinity of the upper end of the intermediate transfer belt 14, and the other one of the transport rolls 42 constitutes a backup roll of the cleaning device 44. Further, a tension roll 46 is disposed above the intermediate transfer belt 14, and an appropriate tension is applied to the intermediate transfer belt 14 by the tension roll 46.

  The image forming unit 16 includes an image forming unit 48 provided on one surface of the intermediate transfer belt 14 and a primary transfer roll 50 provided on the back surface of the intermediate transfer belt 14. The image forming unit 48 is detachable with respect to the image forming apparatus main body 12, and once moved downward, it can be pulled out in the front direction in the figure.

  In FIG. 2, details of the image forming means 16 are shown. The image forming unit 48 includes a photosensitive member 52 facing the intermediate transfer belt 14, a charging device 54 configured to charge the photosensitive member 52, for example, a roll, and an LED (light emitting diode), for example. An exposure device 56 that forms a latent image on the photoconductor 52, a developing device 58 that develops the latent image on the photoconductor 52 formed by the exposure device 56 with toner, and the photoconductor 52 remaining on the photoconductor 52 after transfer. And a cleaning device 60 for cleaning the toner. In this embodiment, the image forming unit 48 is configured by combining a separable photoconductor unit 62 and a developing unit 64. The photoconductor unit 62 includes a photoconductor 52, a charging device 54, an exposure device 56, and a cleaning device 60 in a first housing 66. In the developing unit 64, the developing device 58 is accommodated in the second housing 68. The first housing 66 and the second housing 68 are detachably coupled to form the image forming unit 48.

  The developing device 58 is, for example, a two-component system, and a developer composed of toner and carrier is used. For example, the two augers 70 and 72 arranged in parallel in the horizontal direction and the discharge auger 72 are arranged obliquely above. The developer is stirred by the augers 70 and 72 and supplied to the developing roll 74. In the developing roll 74, a magnetic brush is formed by a carrier, the toner attached to the carrier is conveyed by the magnetic brush, and the latent image on the photosensitive member 52 is developed by the toner. As in this embodiment, in the two-component developing device 58, the developing roll 74 is disposed above the augers 70 and 72, so that the developer is prevented from accumulating and the developer is uniformly stirred. Development performance can be maintained.

  The cleaning device 60 includes a toner scraping unit 76 formed of, for example, a blade, and a collecting unit 78 that collects the toner scraped off by the toner scraping unit 76.

  In the above configuration, the intermediate transfer belt 14 and the photoconductor 52 rotate in opposite directions in synchronization with each other, the surface of the photoconductor 52 is charged by the charging device 54, and a latent image is formed by the exposure device 56. The latent image on the photoreceptor 52 formed by the exposure device 56 is developed by the developing device 58. The toner image developed by the developing device 58 is transferred to the intermediate transfer belt 14 by the primary transfer roll 50. The toner images of the respective colors formed by the image forming units 16 are superimposed as the intermediate transfer belt 14 moves.

  On the other hand, the sheets stacked on the sheet supply cassette 20 of the sheet supply apparatus 18 are fed one by one to the sheet supply path 28 by the pickup roll 22, the feed roll 24, the retard roll 26, and the like. The sheet sent to the sheet supply path 28 comes into contact with the registration roll 30, is temporarily stopped, and is sent to the secondary transfer roll 32 at a timing. The toner image on the intermediate transfer belt 14 is transferred to the sheet by the secondary transfer roll 32. The sheet on which the toner image has been transferred is further sent to the fixing device 34, where the toner image is fixed to the sheet by heat and pressure. The sheet on which the toner image is fixed by the fixing device 34 is discharged to the discharge tray portion 38 by the discharge roll 36.

  In the developing unit 64 described above, a toner cloud is generated between the developing roll 74 and the photosensitive member 52 due to the pressure in the developing unit 64, and the surface of the intermediate transfer belt 14 may be soiled. In particular, the method in which the photosensitive member 52 and the developing roller 64 are rotated in the same direction is advantageous in terms of development quality because toner clogging can be prevented, but the toner cloud is scattered toward the intermediate transfer belt 14. In order to prevent this, it is conceivable to provide a sealing material between the photosensitive member 52 and the developing roll 74. However, this may affect the toner image on the photosensitive member 52 and cause image deterioration.

  Therefore, in this embodiment, the scattering of the toner cloud to the surface of the intermediate transfer belt 14 is suppressed by the structure of the image forming unit 16 and the positional relationship between the plurality of image forming units 16.

In FIG. 3, the positional relationship between the plurality of image forming means 16 is shown. In FIG. 3, “a” is added to each component of the first image forming unit 16 a after the numeral, and each component of the second image forming unit 16 b disposed above and adjacent to the first image forming unit 16 a. Has a b after the number. If a straight line that is perpendicular to the intermediate transfer belt 14 and passes through the second image forming unit 48b side end of the developing roller 74a in the first image forming unit 48a is L, the first image is more than the straight line L. The end of the cleaning device 60b, which is a part of the second image forming unit 48b, is inserted between the developing roller 74a of the first image forming unit 48a and the intermediate transfer belt 14 on the forming unit 48a side. A scattering suppression unit 80 is configured. Accordingly, the toner cloud that is about to be scattered from the developing roll 74a toward the intermediate transfer belt 14 can be prevented from reaching the intermediate transfer belt 14 by the scattering suppression unit 80 serving as a barrier.
In this embodiment, the end of the cleaning device 60b is configured as the scattering suppression unit 80. However, as another embodiment, the scattering suppression unit is positively formed in the second image forming unit 48b. Also good.

  In the first image forming unit 48a, if the radius of the photosensitive member 52a is A and the distance between the intermediate transfer belt 14 and the developing roller 74a closest to the intermediate transfer belt 14 is B, then A <B. Is set to In other words, the possibility that the toner cloud reaches the surface of the intermediate transfer belt 14 is reduced by separating the developing roller 74a from the intermediate transfer belt 14 rather than the radius of the photosensitive member 52a.

In addition, the photosensitive member is placed above the developing device 58a in the vertical direction so that the horizontal width of the photosensitive member unit 62b of the second image forming unit 48b is within the horizontal width of the developing device 58a of the first image forming unit 48a. Units 62b are stacked. Accordingly, the photosensitive member 52b, the charging device 54b, the exposure device 56b, and the cleaning device 6ab 16ab of the second image forming unit 48b are overlapped on the upper part in the vertical direction of the first image forming unit 48a. It is compact by the size.
Although the structure and positional relationship of the first image forming unit 48a and the second image forming unit 48b have been described, the other image forming units also have the same structure and positional relationship.

  As described above, the present invention can be used for a tandem type image forming apparatus that needs to suppress scattering of a toner cloud to an intermediate transfer belt.

1 is a side view showing an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a side view showing an image forming unit used in the image forming apparatus according to the embodiment of the present invention. FIG. 3 is a side view showing the positional relationship of image forming means used in the image forming apparatus in the embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 12 Image forming apparatus main body 14 Intermediate transfer belt 16 Image forming means 48 Image forming unit 50 Primary transfer roll 52 Photoconductor 54 Charging device 56 Exposure device 58 Developing device 60 Cleaning device 62 Photoconductor unit 64 Developing unit 80 Scattering suppression Part

Claims (7)

  A belt and a plurality of image forming units arranged in parallel along the belt, each image forming unit having at least a developing roll, and perpendicular to the belt and in one image forming unit A part of the other image forming unit enters one image forming unit side from the straight line passing through the other image forming unit side end of the developing roll and between the developing roll of the one image forming unit and the belt. An image forming apparatus.   2. The image according to claim 1, wherein each of the image forming units further includes a photoconductor disposed to face the belt, and a portion of the developing roll closest to the belt is separated from the belt by a radius of the photoconductor. Forming equipment.   Each of the image forming units has a cleaning device that cleans toner on the photosensitive member, and a portion that enters one image forming unit side from the straight line is at least a part of the cleaning device. The image forming apparatus described.   The image forming apparatus according to claim 1, wherein the belt is disposed obliquely with respect to a horizontal direction.   A belt and a plurality of image forming units arranged in parallel along the belt, each image forming unit having at least a developing roll, and the toner cloud generated from the developing roll of one image forming unit An image forming apparatus in which a scattering suppression unit that suppresses scattering to the belt side is provided in another image forming unit.   The scattering suppression unit is on the side of one image forming unit with respect to a straight line that is perpendicular to the belt and passes through the other end of the image forming unit on the developing roll in one image forming unit, and the one image forming unit. The image forming apparatus according to claim 5, wherein the image forming apparatus is provided so as to enter between a developing roll of the unit and the belt.   7. The image forming apparatus according to claim 5, wherein each of the image forming units has a cleaning device that cleans the toner on the photosensitive member, and the scattering prevention unit is provided in a cleaning device of another image forming unit.

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