JP4894355B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile machine, and a multi-function machine having a plurality of these functions, and in particular, toner attached to a transfer means for transferring a toner image formed on an image carrier to a recording medium. The present invention relates to an image forming apparatus including a cleaning device for cleaning an object to be cleaned such as paper dust and talc.

  Generally, in an image forming apparatus using an electrophotographic process or the like, an electrostatic latent image corresponding to a document screen is formed on the surface of an image carrier charged to a predetermined potential, and a visible image (toner image) is formed by a developing device. It is formed. The toner image formed on the image carrier reaches the transfer means by the rotation of the image carrier and is transferred to the transfer material conveyed to the transfer means. After the toner image is transferred, residual toner on the image carrier is removed by a cleaning device arranged around the image carrier. Further, a cleaning object disposed on the transfer unit removes an object to be cleaned such as toner attached to the transfer belt.

  In general, a blade method, a fur brush method, a combination method of a blade and a fur brush, or the like is employed as the cleaning means.

  In the transfer belt method, a fur brush method with a smaller contact load than the blade method is suitable.

  The cleaning device of Patent Document 1 has a cleaning blade as a main cleaning mechanism and a cleaning member by an electric field as a sub-cleaning mechanism, and this cleaning device is arranged below the transfer belt that is hardly affected by the heat of the fixing device. Is.

There is also provided an apparatus in which an independent cooling duct is provided between the fixing device and the transfer belt cleaning means to block heat generated by the fixing device and exhaust heat.
Japanese Patent No. 3312800 (FIG. 1)

  When the cleaning unit is moved below the transfer belt as in the cleaning of Patent Document 1 and a plurality of cleaning members are arranged in the cleaning unit, the plurality of cleaning members facing the driving roller for driving the transfer belt are transferred to the transfer belt. Thus, a part of the cleaning member comes into contact with the transfer belt. This necessitates separate arrangement of the cleaning means, resulting in an increase in the size of the cleaning means.

  Further, even if a cooling duct is provided between the fixing device and the cleaning unit, a curvature separation guide member for separating the sheet conveyed by the transfer belt from the transfer belt is provided above the cleaning unit. There is no space for forming means, and it becomes difficult to cool the upper part of the cleaning means.

  The present invention provides a cleaning unit that prevents temperature rise in the cleaning unit by a cleaning unit that is not affected by the heat of the fixing device, has good toner flowability, and ensures good toner transportability. An object is to provide an image forming apparatus provided.

  The above object is solved by the image forming apparatus described below of the present invention.

Image forming means for forming a toner image on an image carrier, transfer means for transferring the toner image to a recording medium, cleaning means for cleaning an object to be cleaned attached to the transfer means, and transferred to the recording medium And a fixing device that fixes the toner image. The image forming device includes a cavity that is disposed between the transfer unit and the fixing device and is formed on a side surface of the cleaning unit that faces the fixing device. A duct means, a fan for blowing or exhausting outside air inside the duct means, a conductive member disposed inside the cavity and abutting against the outer wall of the cleaning means, and a tip portion exposed to the sheet passing surface side, A static elimination member that neutralizes the recording medium conveyed later, the static elimination member is connected to the conductive member, and the conductive member is grounded. Image forming apparatus characterized by there.

  In the image forming apparatus of the present invention, a duct unit that forms a cavity that covers a side surface of the cleaning unit that is disposed between the transfer unit and the fixing unit and that faces the fixing unit, and blows or exhausts outside air into the duct unit. By having a fan and a heat conductive member disposed in the cavity and abutting against the outer wall of the cleaning unit, the cleaning unit disposed in the vicinity of the fixing device is not affected by the fixing heat and blocks heat and dissipates heat. Therefore, the temperature rise of the cleaning means is prevented, the flowability of the waste toner in the cleaning means is good, and good toner discharge is ensured.

  In addition, since residual toner or the like attached to the transfer belt is reliably removed and discharged, it is possible to provide an image forming apparatus that eliminates contamination on the back surface of the recording medium and forms a high-quality image.

  Furthermore, a plurality of cleaning members can be arranged at one place, and the cleaning means can be reduced in size.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[Image forming apparatus]
FIG. 1 is an overall configuration diagram of an image forming apparatus including an image forming apparatus main body A, an image reading apparatus SC, and an automatic document feeder DF.

  The image forming apparatus main body A shown in the figure includes an image forming means comprising a photosensitive member (image carrier) 1, a charging means 2, an image exposure apparatus 3, a developing apparatus 4, a transfer means 5, a cleaning means 6, a cleaning apparatus 8, and the like. The fixing device 9 and a paper transport system are included.

  The paper transport system includes a paper feed cassette 10, a first paper feed unit 11, a second paper feed unit 12, a paper discharge unit 14, a manual paper feed unit 15, a circulation refeed unit 16, and a reverse paper discharge unit 17. It is configured.

  The document d placed on the document table of the automatic document feeder DF is transported by the paper feeding means, and one or both side images of the document d are read by the optical system of the image reading device SC and read by the image sensor CCD. It is. The analog signal photoelectrically converted by the image sensor CCD is subjected to analog processing, A / D conversion, shading correction, image compression processing and the like in the image processing unit 20 and then sent to the image exposure apparatus 3.

  In the image forming unit, processes such as charging, exposure, development, transfer, separation, and cleaning are performed.

  In the image forming means, a charge (in this embodiment, negative charge) is applied to the photosensitive member 1 by the charging means 2, and an electrostatic latent image is formed by laser light irradiation from the image exposure device 3. The electrostatic latent image is visualized by 4 and becomes a toner image (negative charge in the present embodiment). Next, a recording medium (hereinafter referred to as a sheet) P stored in the sheet feeding cassette 10 is conveyed from the first sheet feeding unit 11. The sheet P is conveyed in synchronization with the toner image by the second sheet feeding means 12 made up of registration rollers, the traveling position of the leading edge of the sheet P is detected by a detection sensor (not shown), and the information is sent to the control means 100. Then, the entry timing to the transfer nip portion N1 is calculated. Thereafter, the sheet P is electrostatically attracted to the transfer belt 51 after the toner image is transferred at the transfer nip portion N1 formed by the transfer belt 51 of the transfer unit 5 and the photosensitive member 1, and the drive roller 52 The toner is separated from the transfer belt 51 by curvature separation and fixed at a fixing nip portion N2 formed by the fixing roller 91 and the pressure roller 92 of the fixing device 9. Details regarding the transfer according to the present invention will be described later.

  The paper P after fixing is discharged out of the apparatus by the paper discharge means 14. On the other hand, the transfer residual toner on the photoreceptor 1 is removed by the cleaning device 8 which is a cleaning means. In the case of double-sided copying, the paper P on which the image is formed on the first side is sent to the circulation refeed unit 16 and reversed, and after the image is formed again on the second side in the image forming unit, the paper discharge unit 14 is formed. Is discharged out of the apparatus. In the case of reverse paper discharge, the paper P branched from the normal paper discharge path is switched back by the reverse paper discharge means 17 and turned upside down, and then discharged from the apparatus by the paper discharge means 14.

[Transfer means]
FIG. 2 is a cross-sectional view of the image forming unit, the cleaning unit, and the fixing device 9 arranged around the photoreceptor 1.

  The transfer means 5 includes a transfer belt 51 on rollers such as a drive roller 52 made of stainless steel (SUS), a driven roller 53 made of aluminum alloy, a backup roller 54 made of urethane foam, a transfer bias roller 55 made of stainless steel (SUS), and the like. Is stretched.

  A voltage having a polarity opposite to that of the toner is applied to the bias roller 55. The backup roller 54 is formed of foamed urethane rubber.

[Cleaning means]
FIG. 3 is a sectional view of the cleaning means 6.

  The cleaning means 6 has a first brush roller 61 and a second brush roller 62 that are rotatable in reverse directions and are in contact with the transfer belt 51 of the transfer means 5 to remove the toner. A sliding contact member 63 disposed parallel to the common tangential direction of the first brush roller 61 and the second brush roller 62 and slidably contacting the first brush roller 61 and the second brush roller 62, and a conveying screw 64. Have.

  These members of the cleaning means 6 are accommodated in the housing 65.

  The first brush roller 61 and the second brush roller 62 are fur brushes that are arranged to have a predetermined distance from each other via a sliding contact member 63, and are made of conductive fibers having a high electric resistance value. . The bias polarity applied to the first brush roller 61 and the second brush roller 62 is opposite.

  The driving roller 52 facing the first brush roller 61 and the second brush roller 62 has conductivity and is grounded.

  One common sliding contact member 63 that scrapes off toner from the first brush roller 61 and the second brush roller 62 is formed of a non-conductive resin member. An arrow-shaped scraping portion 63 </ b> A formed at one end (upper part in the drawing) of the sliding contact member 63 connects the rotation shaft of the first brush roller 61 and the rotation shaft of the second brush roller 62. It is provided near the straight line. The other end (lower part in the drawing) of the sliding contact member 63 is extended in the vicinity of the outer diameter of the conveying screw 64 that conveys the object to be cleaned.

  The toner scraped off by the first brush roller 61 is isolated by the sliding contact member 63 and does not enter the second brush roller 62 and mix. Further, the toner scraped off by the second brush roller 62 does not return to the second brush roller 62 and mix.

[Duct means]
FIG. 4 is a partially enlarged sectional view of the cleaning means 6 and the duct means 7.

  3 and 4, the duct unit 7 is fixed to the side surface of the cleaning unit 6 that cleans the transfer belt 51 that faces the fixing device 9. The duct means 7 includes a duct housing 71 that forms a cavity 72, a conductive member 73, a paper guide member 74, a charge eliminating member 75, a blower means 76, and the like.

  The duct housing 71 is connected to the side surface side of the housing 65 of the cleaning means 6 and forms a cavity 72 covered with the duct housing 71. The conductive member 73 is disposed in the cavity 72 and is fixed to the side surface portion and the upper surface portion of the housing 65. The conductive member 73 is formed of a stainless steel plate having a plate thickness of 0.5 mm.

  The paper guide member 74 is molded of a resin material and shields the upper surface of the housing 65, and the upper surface guides the paper P that is separated from the transfer belt 51 by the curvature and conveys it to the fixing device 9.

  The charge removal member 75 is a conductive thin plate having a plurality of protrusions formed in a sawtooth shape. The neutralizing member 75 may be formed separately and then fixed to the conductive member 73, or may be formed integrally with the conductive member 73. The front end portion of the charge removal member 75 is fixed at a position retracted from the upper surface portion of the paper guide member 74 by a step g of about 0.5 mm. The neutralizing member 75 neutralizes the sheet P conveyed in a manner that is separated from the transfer belt 51 by a curvature without contact.

  The blowing unit 76 introduces outside air into the cavity 72 and discharges the air in the cavity 72 whose temperature has been increased by heat from the fixing device 9 in the direction of the white arrow shown in FIG. 5 to prevent the temperature of the cleaning unit 6 from increasing. To do. The air blowing means 76 may be an exhaust fan.

  5A is a plan view of the transfer unit 5, the cleaning unit 6, and the duct unit 7, and FIG. 5B is a front sectional view.

  The air blowing means 76 of the duct means 7 is composed of an electric sirocco fan or the like, and is connected to the air blowing pipe 77. The illustrated blowing means 76 has the blowing means 76 installed on the front side of the image forming apparatus main body A, and the blower pipe 77 is arranged from the front side to the back side of the image forming apparatus main body A to cool the cleaning means 6. Outside air is exhausted to the back side of the image forming apparatus main body A.

  The blowing means 76 sucks outside air from the intake opening and discharges it from the exhaust opening, and sends the outside air to the blowing pipe 77 to cool the housing 65 of the cleaning means 6 and the side and bottom surfaces of the conductive member 73.

  Instead of the blowing unit 76, an electric exhaust unit may be provided on the back side of the image forming apparatus main body A.

  FIG. 6 is a cross-sectional view showing another embodiment of the duct means 7.

  A plurality of heat radiating fins 78 are arranged on the hollow side of the conductive member 73 to improve the cooling effect of the housing 65 and the conductive member 73.

  Further, by providing cooling means such as a Peltier element in the cavity 72, the cooling effect can be further improved.

1 is an overall configuration diagram of an image forming apparatus including an image forming apparatus main body, an image reading apparatus, and an automatic document feeder. FIG. 3 is a cross-sectional view of an image forming unit, a cleaning unit, and a fixing device. Sectional drawing of a cleaning means. The partial expanded sectional view of a cleaning means and a duct means. Plan view of transfer means, cleaning means, and duct means Sectional drawing which shows other embodiment of a duct means.

Explanation of symbols

DESCRIPTION OF SYMBOLS 5 Transfer means 51 Transfer belt 52 Drive roller 53 Drive roller 54 Backup roller 55 Transfer bias roller 6 Cleaning means 61 1st brush roller 62 2nd brush roller 63 Sliding contact member 64 Conveying screw 65 Housing 7 Duct means 71 Duct housing 72 Cavity 73 Conductive member 74 Paper guide member 75 Static elimination member 76 Blowing means 77 Blow pipe 78 Radiation fin 8 Cleaning device 9 Fixing device

Claims (2)

Image forming means for forming a toner image on an image carrier, transfer means for transferring the toner image to a recording medium, cleaning means for cleaning an object to be cleaned attached to the transfer means, and transferred to the recording medium An image forming apparatus having a fixing device for fixing the toner image;
A duct unit disposed between the transfer unit and the fixing device and having a cavity formed on a side surface of the cleaning unit facing the fixing unit;
A fan for blowing or exhausting outside air into the duct means;
A conductive member disposed inside the cavity and abutting against an outer wall of the cleaning means;
A charge removal member that discharges the recording medium that is exposed on the paper passing surface side and conveyed after transfer;
Have
The image forming apparatus , wherein the charge removal member is connected to the conductive member, and the conductive member is grounded . The image forming apparatus according to claim 1, wherein the transfer unit is a transfer belt constituted by an endless belt.

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