JP2005043684A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus equipped with a fixing device where a jamming treatment is facilitated even in the case a transfer material is wound on a heating roller member, and also, such failures are prevented that a cleaning means for the heating roller member and an oil apply means for the heating roller member are soiled by toner and the transfer material sticks to the heat roller member. <P>SOLUTION: In the image forming apparatus, one or more 2nd guide members coming close to the heat roller member are arranged on the downstream side of the heat roller member in the rotating direction. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus including a fixing device provided in an electrophotographic copying machine, a printer, a facsimile, or the like.

Conventionally, in order not to damage the heating roller member of the fixing roller composed of the heating roller member and the pressure roller member, for example, a guide member such as a separation claw or a guide plate is disposed with a slight interval to the heating roller member, A method of separating a transfer material from a heating roller member with a guide member close to the heating roller member is known (see Patent Document 1).
JP-A-3-54587

  However, as long as there is a gap between the guide member and the heating roller member, the transfer material enters the gap, and the transfer material is completely wrapped around the heating roller member, or the oil application means that has been cleaned is soiled with toner, or the transfer material is transferred. There is a problem that the transfer material cannot be processed due to the material sticking to the heating roller member.

  The present invention solves the above problems, and even if the transfer material is wound around the heating roller member, it facilitates jamming, and the cleaning means of the heating roller member and the oil application means of the heating roller member are soiled with toner, An object of the present invention is to provide an image forming apparatus including a fixing device that prevents a transfer material from sticking to a heating roller member.

  The above object has a fixing roller composed of a heating roller member and a pressure roller member, and a first guide member that is close to the fixing roller and guides the transfer material from the fixing roller, and a toner image on the transfer material. An image forming apparatus comprising a fixing device for fixing the image forming apparatus, further comprising one or more second guide members adjacent to the heating roller member on the downstream side in the rotation direction of the heating roller member. Achieved by:

  The present invention adopts the above-described configuration, so that even when the transfer material is wound around the heating roller member, the jamming process is facilitated and the heating roller member cleaning means and the heating roller member oil application means are stained with toner. An image forming apparatus including a fixing device that prevents the transfer material from sticking to the heating roller member is provided.

  According to claim 1, even if the transfer material winds around the heating roller member and passes through the first guide member, the curvature of the heating roller member, the waist of the transfer material, or the transfer material until the next second guide member. Is sufficiently heated, it becomes easy to separate the transfer material from the heating roller member, and it is possible to provide an image forming apparatus including a fixing device that completely prevents the transfer material from being wound around the heating roller member. Become.

  According to the second aspect, by providing the second guide member in front of the first guide member and the cleaning means for the heating roller member, the oil application means, etc., toner contamination on these members is prevented. Further, it is possible to prevent the transfer material from being attached to the heating roller member.

  According to the third aspect, the second guide member is guided in a substantially tangential direction with respect to the rotation direction of the heating roller member, thereby further preventing the transfer material from slipping through the heating roller member.

  According to the fourth aspect, by providing the second guide member with the fluororesin, the transfer material is difficult to stick to the second guide member, and the transfer material is prevented from slipping from the heating roller member.

  Embodiments of the present invention will be described below. The description in this column does not limit the technical scope of the claims or the meaning of terms. In addition, the following assertive description in the embodiment of the present invention shows the best mode, and does not limit the meaning or technical scope of the terms of the present invention.

  (1) An image forming apparatus provided with a fixing device according to the present invention will be described below with reference to FIG.

  According to FIG. 1, the image forming apparatus GS includes an image forming apparatus main body GH and an image reading apparatus SC provided on the upper portion of the image forming apparatus main body GH.

  The image forming apparatus main body GH is called a tandem type color image forming apparatus, and yellow (Y), magenta (M), cyan (C), and black along the moving direction of the intermediate transfer belt 6 as an intermediate transfer body. An image forming unit for forming each color toner image of (K) is disposed, and the color toner image formed on the image carrier of each image forming unit is transferred onto the intermediate transfer belt 6 and superimposed, and then transferred. The transfer is performed collectively on the material (recording paper P).

  In the figure, a document image placed on an image reading device SC disposed above the image forming apparatus main body GH is scanned and exposed by an optical system, read into a line image sensor CCD, and subjected to photoelectric conversion by the line image sensor CCD. The analog signal thus processed is subjected to analog processing, A / D conversion, shading correction, image compression processing, and the like in an image processing unit, and then an image data signal is sent to the exposure optical system 3 as image writing means.

  Also, in the drawing, four sets of process units 100 are provided on the peripheral edge of the intermediate transfer belt 6 for forming an image for each color of yellow (Y), magenta (M), cyan (C), and black (K). As image forming means, they are arranged in tandem in the vertical direction along the intermediate transfer belt 6 with respect to the rotation direction of the intermediate transfer belt 6 in the vertical direction indicated by the arrows in the figure, and arranged in the order of Y, M, C, K. ing.

  Each of the four sets of process units 100 has a common structure, and each includes a photosensitive drum 1 as an image carrier, a charger 2 as a charging unit, an exposure optical system 3 as an image writing unit, and development. It comprises a developing device 4 as a means and a photoreceptor cleaning device 190 as an image carrier cleaning means.

  The photosensitive drum 1 that is an image carrier is a layer thickness (film thickness) as a photosensitive layer thickness on the outer periphery of a cylindrical base formed of a metallic member such as aluminum having an outer diameter of about 40 to 100 mm. A photoconductive layer of an organic photoreceptor layer (OPC) having a thickness of about 20 to 40 μm is formed. The photosensitive drum 1 is rotated by power from a driving source (not shown) in a direction indicated by an arrow with the conductive layer grounded, for example, at a linear velocity of about 80 to 280 mm / s, preferably 220 mm / s. .

  Around the photosensitive drum 1, an image forming unit including a charging unit 2 as a charging unit, an exposure optical system 3 as an image writing unit, and a developing unit 4 as a developing unit is indicated by an arrow in the figure. It arrange | positions with respect to the rotation direction of the photoreceptor drum 1 to show.

  The charger 2 as the charging means is attached in close proximity to the photosensitive drum 1 in a direction orthogonal to the moving direction of the photosensitive drum 1 (the vertical direction in the drawing). The charger 2 includes a discharge wire as a corona discharge electrode that applies a predetermined potential to the organic photoreceptor layer of the photoreceptor drum 1 and is charged by a corona discharge having the same polarity as the toner (in this embodiment, negatively charged). To apply a uniform potential to the photosensitive drum 1.

  An exposure optical system 3 serving as an image writing means rotationally scans laser light emitted from a semiconductor laser (LD) light source (not shown) in a main scanning direction by a rotating polygon mirror (no symbol), and an fθ lens (no symbol). ), Exposure on the photosensitive drum 1 through an electric signal corresponding to the image signal (image writing) through a reflecting mirror (not shown), etc., and corresponding to the original image on the photosensitive layer on the surface of the photosensitive drum 1. An electrostatic latent image is formed.

  The developing device 4 as a developing unit is configured to receive a two-component developer of each color of yellow (Y), magenta (M), cyan (C), or black (K) charged to the same polarity as the charging polarity of the photosensitive drum 1. Each is provided with a developing roller 4a which is a developer carrying member formed of, for example, a cylindrical nonmagnetic stainless steel or aluminum material having a thickness of 0.5 to 1 mm and an outer diameter of 15 to 25 mm. The developing roller 4a is kept in contact with the photosensitive drum 1 with a predetermined gap (for example, 100 to 1000 μm) by an abutment roller (not shown), and rotates in the forward direction and the rotational direction of the photosensitive drum 1. At the time of development, a photoconductor drum is applied by applying to the developing roller 4a a DC voltage having the same polarity as the toner (negative polarity in the present embodiment) or a developing bias voltage that superimposes an AC voltage on the DC voltage. The reversal development is performed on the upper exposed portion. As the developer (toner) used for the reversal development, styrene acrylic polymerized toner is used.

The intermediate transfer belt 6 that is an intermediate transfer member has a volume resistivity of about 1.0 × 10 ^{7 to} 1.0 × 10 ⁹ Ω · cm and a surface resistivity of 1.0 × 10 ^{10 to} 1.0 × 10. Semi-conductive endless (seamless) resin belt members of about ¹² Ω / □ are used. For example, engineering plastics such as modified polyimide, thermosetting polyimide, ethylene tetrafluoroethylene copolymer, polyvinylidene fluoride, nylon alloy, etc. A semiconductive resin film substrate having a thickness of 0.05 to 0.5 mm in which a conductive material is dispersed. As the base of the intermediate transfer belt 6, a semiconductive rubber belt having a thickness of 0.5 to 2.0 mm in which a conductive material is dispersed in silicon rubber or urethane rubber can be used. The intermediate transfer belt 6 is wound around a plurality of roller members including a tension roller 6a, and is supported rotatably in a vertical method. It is also possible to use a drum-shaped intermediate transfer member.

  The primary transfer roller 7 as a primary transfer unit for each color is made of a roller-like conductive member using foamed rubber such as silicon or urethane, and the photosensitive drum 1 for each color with the intermediate transfer belt 6 interposed therebetween. The transfer area is formed between the intermediate transfer belt 6 and the photosensitive drum 1 by pressing the back surface of the intermediate transfer belt 6. A DC constant current having a polarity opposite to that of the toner (positive polarity in the present embodiment) is applied to the primary transfer roller 7 by constant current control, and a toner image on the photosensitive drum 1 is generated by a transfer electric field formed in the transfer area. Is transferred onto the intermediate transfer belt 6.

  The image forming process (image forming process) will be described below.

  When the image recording is started, the photosensitive drum drive motor (not shown) is rotated to rotate the Y photosensitive drum 1 in the direction indicated by the arrow in the figure, and a potential is applied to the Y photosensitive drum 1 by the Y charger 2. . After the Y photosensitive drum 1 is applied with a potential, the Y exposure optical system 3 performs exposure (image writing) with an electrical signal corresponding to the first color signal, that is, the Y image data. An electrostatic latent image corresponding to a yellow (Y) image is formed on the body drum 1. The latent image is reversely developed by the Y developing device 4 to form a toner image made of yellow (Y) toner on the Y photosensitive drum 1. The Y toner image formed on the Y photosensitive drum 1 is transferred onto the intermediate transfer belt 6 by a primary transfer roller 7 as a primary transfer means.

  Next, a potential is applied to the M photosensitive drum 1 by the M charger 2. After the potential is applied to the M photoconductor drum 1, the M exposure optical system 3 performs exposure (image writing) with an electrical signal corresponding to the first color signal, that is, the M image data, and the M photosensitivity. An electrostatic latent image corresponding to a magenta (M) image is formed on the body drum 1. The latent image is reversely developed by the M developing device 4, and a toner image made of yellow (M) toner is formed on the M photosensitive drum 1. The M toner image formed on the M photoconductor drum 1 is transferred onto the intermediate transfer belt 6 by superimposing the Y toner image by a primary transfer roller 7 as a primary transfer unit.

  By a similar process, a toner image made of cyan (C) toner formed on the C photoconductive drum 1 and a toner image made of black (K) toner formed on the K photoconductive drum 1 are obtained. The toner images are sequentially superimposed on the intermediate transfer belt 6, and a superimposed color toner image composed of Y, M, C, and K toners is formed on the peripheral surface of the intermediate transfer belt 6.

  The toner remaining on the peripheral surface of each photoreceptor drum 1 after the transfer is cleaned by a photoreceptor cleaning device 190 as an image carrier cleaning means.

  On the other hand, the recording paper P as a transfer material accommodated in the paper feed cassettes 20A, 20B, and 20C is fed by a feed roller 21 and a paper feed roller 22A provided in the paper feed cassettes 20A, 20B, and 20C, respectively, and conveyed. Via the rollers 22B, 22C, 22D and the registration roller 23, the toner is conveyed to a secondary transfer roller 7A as a secondary transfer means to which a voltage having a polarity opposite to that of the toner (in this embodiment, a positive polarity) is applied. Overlaid color toner images (color images) formed on the intermediate transfer belt 6 are collectively transferred onto the recording paper P in the transfer area of the roller 7A.

  The recording paper P onto which the color image has been transferred is heated and pressed at a fixing nip NA formed by a heating roller 17a and a pressure roller 17b of an oilless fixing device 17 described in detail later, and is discharged. It is sandwiched between paper rollers 24 and placed on a paper discharge tray 25 outside the apparatus. Further, TSBa is provided on the exit side of the fixing nip portion NA, on the downstream side in the rotation direction of the heating roller 17a with respect to the fixing nip portion NA, facing the heating roller 17a and close to non-contact. The transfer material intrusion prevention plate GBa is a separation guide plate that is provided on the exit side of the fixing nip NA and is opposed to the pressure roller 17b with a small gap in a non-contact manner.

  The intermediate transfer belt 6 that has separated the curvature of the recording paper P after the color image is transferred onto the recording paper P by the secondary transfer roller 7A as the secondary transfer means is an intermediate transfer body as the intermediate transfer body cleaning means. The residual toner is removed by the cleaning device 190a.

  At the time of double-sided image formation, a color image (color toner image) is formed on one side (first side (front side)), and the recording paper P discharged from the fixing device 17 is branched from the sheet discharge path by the branching unit 26. Then, after passing through the lower circulating paper path 27A that constitutes the paper feeding / conveying means, the front and back are reversed by the reversing conveyance path 27B that is a refeeding mechanism (ADU mechanism), and passes through the refeeding conveyance section 27C. Then, they merge at the paper feed roller 22D. The recording paper P that has been reversed (circulated and reversed) is again conveyed to the secondary transfer roller 7A via the timing roller 23, and a color image (second surface (back surface)) on the other side (second surface (back surface)) of the recording paper P. A color toner image) is collectively transferred. The recording paper P onto which the color image has been transferred is heated and pressed again at the fixing nip NA formed by the heating roller 17a and the pressure roller 17b of the oilless fixing device 17, and the paper discharge roller 24 is fixed. And placed on a paper discharge tray 25 outside the apparatus.

  On the other hand, after the color image is transferred to the recording paper P by the secondary transfer roller 7A, the residual toner is removed by the intermediate transfer body cleaning unit 8A from the intermediate transfer belt 6 from which the recording paper P is separated by curvature.

  In the description of the image forming apparatus, the color image formation is described. However, the present invention includes a case where a monochrome image is formed.

  (2) Next, a fixing device according to the present invention will be described below with reference to FIG. FIG. 2 is a schematic cross-sectional view of a fixing device including a second guide member according to the present invention.

  As shown in FIG. 2, the oilless fixing device 17 of the present invention includes a heating roller 17a as an upper roll-shaped heating roller member for fixing a toner image on a recording paper P as a transfer material, and an upper side. A pressure roller 17b as a lower roll-shaped pressure roller member that is pressed against and abutted against the heating roller 17a, and a rotation direction of the heating roller 17a with respect to the fixing nip NA on the exit side of the fixing nip NA. On the downstream side, a guide plate GPa as a first guide member provided in close proximity to the heating roller 17a in close contact with the fixing nip portion NA and the guide plate GPa on the outlet side of the fixing nip portion NA. On the downstream side of the heating roller 17a in the rotation direction, a transfer material intrusion prevention plate TSBa as a second guide member provided in close proximity to the heating roller 17a in a non-contact manner, and a fixing nip portion The outlet side of A, composed of a separating guide plate GBa provided with a gap narrow in the non-contact opposite to the pressure roller 17b.

  A heating roller 17a having a halogen lamp HLa as a heating source inside is made of, for example, an aluminum material and has a thickness of about 1 to 8 mm, preferably a cylindrical metal pipe 171a of about 5 mm, and an outer periphery of the metal pipe 171a. For example, a silicon material is used for the surface, the thickness (thickness) is about 1 to 3 mm, preferably 1.5 mm, and the rubber hardness is about 70 to 80 degrees (Asker C), preferably 72 degrees. A rubber roller layer 172a as an elastic body, and a release layer 173a made of PFA (perfluoroalkoxy) coating or PFA (perfluoroalkoxy) coating having a thickness of about 15 to 50 μm and covering the surface of the rubber roller layer 172b. The formed roller member has an outer diameter of about 55 to 70 mm, preferably 65 mm. Further, as the halogen lamp HLa provided inside the heating roller 17a, two lamps of about 750 W are used in this embodiment. The two halogen lamps HLa having a rating of 230V are used at 220V.

  As the pressure roller 17b, for example, a cylindrical metal pipe 171b having a thickness of about 2 to 5 mm using an aluminum material, and a silicon material, for example, is used for the outer peripheral surface of the metal pipe 171b. A rubber roller layer 172b as a hard elastic body having a thickness of about 0.8 to 1.2 mm, preferably 1.0 mm, and a rubber hardness of about 80 to 90 degrees (Asker C), preferably 83 degrees; A hard rubber roller member having an outer diameter of about 45 to 65 mm, preferably 55 mm, in which a surface of the rubber roller layer 172 b is formed with a release layer 173 b having a coating thickness of about 15 to 50 μm or a PFA (perfluoroalkoxy) coating. Configured as Further, as shown in the drawing, a halogen lamp HLa as a heating source may be provided inside the pressure roller 17b. Further, as the halogen lamp HLa provided inside the pressure roller 17b, one of about 550 W is used in this embodiment. One halogen lamp HLa having a rating of 230V is used at 220V.

  A guide plate GPa as a first guide member provided in close proximity to the heating roller 17a (upper roller) is made of PTFE (polytetrafluoroethylene) on the surface of a heat resistant resin such as a stainless steel plate or polyimide (PI). ) A coating or PFA (perfluoroalkoxy) is used, and it is fixed to a fixing member (not indicated) of the fixing device 17. The guide plate GPa is disposed with an interval (gap) to the heating roller 17a of about 0.1 to 3.0 mm.

  A transfer material intrusion prevention plate TSBa serving as a second guide member, which is provided in a non-contact proximity to the heating roller 17a (upper roller) on the downstream side in the rotation direction of the heating roller 17a with respect to the guide plate GPa, is a stainless steel plate, for example. And a surface of a heat-resistant resin such as polyimide (PI) or the like, which is subjected to PTFE (polytetrafluoroethylene) coating or PFA (perfluoroalkoxy), and is fixed to a fixing member (no symbol) of the fixing device 17. . The transfer material intrusion prevention plate TSBa is disposed with an interval (gap) to the heating roller 17a of about 0.1 to 3.0 mm. Further, a plurality of transfer material intrusion prevention plates may be provided.

  The separation guide plate GBa provided in a non-contact manner with a narrow gap on the pressure roller 17b (lower roller) is coated with PTFE (polytetrafluoroethylene) on the surface of a heat resistant resin such as a stainless steel plate or polyimide (PI). Or a PFA (perfluoroalkoxy) coating, a PTFE (polytetrafluoroethylene) film, or the like is used, and is fixed to a fixing member (not indicated) of the fixing device 17. The separation guide plate GBa is disposed with an interval (gap) of about 0.1 to 0.5 mm from the pressure roller 17b.

  The heating roller 17a (upper roller) is maintained at a temperature of 200 ° C., and the pressure roller 17b (lower roller) is maintained at a temperature of 140 ° C. or less, and between the upper heating roller 17a and the lower pressure roller 17b. The recording paper P is sandwiched between fixing nip portions NA (nip portion) having a width of about 5 to 15 mm and heated and pressure is applied. The color toner image is well fused and fixed.

  Further, a temperature sensor TS1 that is in contact with or not in contact with the heating roller 17a is provided to control the temperature of the heating roller 17a and the pressure roller 17b.

  With the configuration as described above, even when the recording paper P is wound around the heating roller 17a and passes through the guide plate GPa, the curvature of the heating roller 17a, the waist of the recording paper P, or the recording paper until the next transfer material entry prevention plate TSBa. Since P is sufficiently heated, the recording paper P is easily separated from the heating roller 17a, and the recording paper P is completely prevented from being wound around the heating roller 17a.

  As described above, even if the transfer material is wound around the heating roller member and passes through the first guide member, the curvature of the heating roller member, the waist of the transfer material, or the transfer material is sufficiently heated up to the next second guide member. Accordingly, the transfer material can be easily separated from the heating roller member, and an image forming apparatus including a fixing device that completely prevents the transfer material from being wound around the heating roller member can be provided.

  Further, as shown in FIG. 2, the transfer material intrusion prevention plate TSBa is disposed in the vicinity of the heating roller 17a, and further cleans the heating roller 17a on the upstream side of the guide plate GPa in the rotation direction of the heating roller 17a. It is disposed upstream of the heating roller cleaning roller CLa as a means. Further, an oil applying means for applying oil to the heating roller 17a may be disposed upstream of the heating roller cleaning roller CLa. CLW is a cleaning web for cleaning the heating roller cleaning roller CLa.

  As described above, the transfer material intrusion prevention plate TSBa is provided in front of the guide plate GPa and the heating roller cleaning roller CLa of the heating roller 17a or the oil applying means, thereby preventing toner contamination on those members. Further, the process of sticking the recording paper P to the heating roller 17a can be prevented.

  As shown in FIG. 2, the tip of the transfer material intrusion prevention plate TSBa is provided on the upstream side in the rotation direction of the heating roller 17a so as to be guided in the tangential direction with the heating roller 17a.

  As described above, by guiding the transfer material intrusion prevention plate TSBa in a substantially tangential direction with respect to the rotation direction of the heating roller 17a, the slip of the recording paper P from the heating roller 17a is further prevented.

  As shown in FIG. 2, the transfer material entry prevention plate TSBa is provided (applied) with a fluororesin coating, a fluororesin film, or the like.

  As described above, by providing the transfer material intrusion prevention plate TSBa with fluororesin, the recording paper P becomes difficult to stick to the transfer material intrusion prevention plate TSBa, and the recording paper P is prevented from slipping through the heating roller 17a.

  As described above, by adopting the configuration of the present invention, even when the transfer material is wound around the heating roller member, the jam treatment can be easily performed, and the heating roller member cleaning means and the heating roller member oil applying means can be used as a toner. Thus, an image forming apparatus having a fixing device that prevents the transfer material from being stained or the transfer material from sticking to the heating roller member is obtained.

1 is a cross-sectional configuration diagram of a main part of an embodiment of a color image forming apparatus including a fixing device according to the present invention. It is a schematic sectional drawing of a fixing device provided with the 2nd guide member concerning the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photosensitive drum 2 Charging device 3 Exposure optical system 4 Developing device 6 Intermediate transfer belt 7 Primary transfer roller 7A Secondary transfer roller 17 Fixing device 17a Heating roller 17b Pressure roller 100 Process unit 171a, 171b Core metal 172a, 172b Rubber roller Layers 173a, 173b Release layer CLa Heating roller cleaning roller GPa guide plate GBa separation guide plate NA fixing nip TSBa transfer material entry prevention plate P recording paper

Claims (4)

A fixing roller having a fixing roller composed of a heating roller member and a pressure roller member, and a first guide member that is adjacent to the fixing roller and guides the transfer material from the fixing roller, and fixes the toner image on the transfer material. In an image forming apparatus including the apparatus,
An image forming apparatus, further comprising one or more second guide members adjacent to the heating roller member on the downstream side in the rotation direction of the heating roller member. The second guide member is disposed in proximity to the first guide member and the heating roller member, and cleaning means for cleaning the heating roller member in the rotation direction of the heating roller member, or the heating roller member The image forming apparatus according to claim 1, wherein the image forming apparatus is disposed on an upstream side of an oil application unit that applies oil to the liquid. 3. The image forming apparatus according to claim 1, wherein a leading end portion of the second guide member is guided in a direction tangential to the heating roller member at an upstream side in a rotation direction of the heating roller member. . The image forming apparatus according to claim 1, wherein the second guide member is provided with a fluororesin.

Images