JP2009300666A - Fixing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing device which is improved in durability by uniformizing the surfaces of a fixing roller and the fixing member of a fixing belt with a simple configuration. <P>SOLUTION: The fixing device includes: the fixing member rotated to come into contact with a toner image on a recording material; and a polishing member containing abrasive grains having a predetermined grain size and coming into contact with the fixing member. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fixing device including a fixing roller and a fixing belt that abuts a toner image on a recording material, and an image forming apparatus including the fixing device.

  In an electrophotographic image forming apparatus such as a copying machine, a printer, a facsimile machine, or a multifunction machine having these functions, a latent image corresponding to an original is formed on a photosensitive drum, and toner is applied to the latent image. Thus, the visualized toner image is transferred to a recording material, and then the toner image of the recording material is fixed and discharged.

  When a color image is formed, Y, M, C, and K latent images corresponding to the original color are formed on the four photosensitive drums, respectively, and the visualized four color toner images are endless. After the primary transfer onto the intermediate transfer belt, the toner image transferred onto the recording material is fixed and discharged after the secondary transfer onto the recording material.

  As a fixing device for fixing a toner image in this manner, a recording material onto which a toner image has been transferred is sandwiched between a fixing roller having a built-in halogen lamp and a pressure roller that presses the fixing roller. There is a heat roller fixing type fixing device that heats and pressurizes while carrying. Such a fixing device is widely used because of its simple configuration.

  In addition, the fixing belt includes an endless fixing belt that is stretched around a heating roller including a halogen heater and the like, and is driven to circulate, and a pressure roller that presses the fixing roller through the fixing belt. A belt-fixing type fixing device that heats and presses a recording sheet on which a toner image has been transferred is sandwiched and conveyed at a nip formed by a pressure roller is also widely used. Such a belt fixing device has the advantages that the warming capacity of the heating roller of the fixing belt is small, so that the warm-up time is shortened and the energy is saved.

  Further, since the toner of the toner image of the recording material is heated when passing through the nip portion, the toner acts like an adhesive, and the recording paper that has passed through the nip portion does not separate without fixing the fixing roller or the fixing belt. There is a risk of wrapping around the surface and causing jamming. For this purpose, a separation claw having a sharp tip is disposed on the paper discharge side of the nip, and the tip of the separation claw is brought into pressure contact with the surface of the fixing roller or the fixing belt to fix the recording material to the fixing roller or the fixing. Separation methods for peeling from a belt are known.

  By the way, in such a fixing device, when a large number of recording materials are fixed, fine wrinkles or irregularities are formed on the surface of the fixing roller or the fixing belt due to edges in the width direction of the recording material, generated paper dust, pressure contact of the separation claw, and the like. Will occur. As a result, the gloss of the image of the recording material fixed at the part where wrinkles or dents are formed on the fixing roller or the like due to the effect of oil applied to the surface of wax or fixing roller in the toner is different from other parts, The difference in gloss becomes conspicuous. In this case, the line drawing is not so noticeable, but it is easily noticeable in a solid image such as a photographic image.

  The surface of the fixing roller or the like is coated with a fluororesin such as PFA (perfluoro resin) or PTFE (tetrafluoroethylene resin) as a surface layer so that the toner does not adhere to the surface. It is difficult to increase the hardness. Therefore, it is conceivable to increase the thickness of the surface layer, but heat conduction becomes insufficient and fixing performance deteriorates. Further, if the outer diameter of the fixing roller is increased, the chance of wrinkling is reduced, but the heat capacity is increased and the power consumption is increased, which is disadvantageous in terms of space.

On the other hand, in order to prevent an offset phenomenon in which a part of toner adheres to the surface of the fixing roller or the like and the toner adheres to the image, the cleaning web is cleaned by bringing the cleaning web into contact with the surface of the fixing roller or the like. Means to do this is widely known conventionally (see, for example, Patent Document 1).
JP 2001-343854 A

  As described above, a proper measure for removing wrinkles on the fixing roller or the like has not been known. For this reason, when an undesired image is formed by wrinkles, it is determined that the life has expired, and the fixing roller and the like are replaced, which is an obstacle to improving the durability of the fixing device. Further, it is difficult to remove and uniformize wrinkles on the surface of the fixing roller or the like with the cleaning web.

  SUMMARY OF THE INVENTION The present invention has been made in view of such a problem. A fixing device capable of uniformizing the surface property of a fixing member of a fixing roller or a fixing belt with a simple configuration and improving durability, and the fixing device. It is an object of the invention to propose an image forming apparatus provided.

  The object is achieved by the invention described below.

1. A fixing member that rotates and contacts the toner image on the recording material;
A polishing member containing abrasive grains of a predetermined particle size and abutting against the fixing member;
A fixing device comprising:

  2. 2. The fixing device according to claim 1, wherein the fixing member is a fixing roller having a built-in heating unit.

  3. 2. The fixing device according to claim 1, wherein the fixing member is a fixing belt stretched around a plurality of rollers.

  4). The fixing device according to any one of 1 to 3, wherein the polishing member is a film coated with predetermined abrasive grains.

  5). 4. The fixing device according to any one of 1 to 3, wherein the polishing member is a brush roller in which fibers containing predetermined abrasive grains are implanted.

  6). 6. The fixing device according to claim 1, wherein the polishing member contacts the fixing member every predetermined number of fixing sheets.

  7. The fixing device according to any one of 1 to 6, wherein the abrasive grains contained in the polishing member have a particle size of 3 μm or more and 30 μm or less.

  8). An image forming apparatus comprising the fixing device according to any one of 1 to 7 above.

  According to the fixing device and the image forming apparatus including the fixing device of the present invention, the surface property of the fixing member of the fixing roller or the fixing belt can be made uniform with a simple configuration, and the durability can be improved.

  Hereinafter, the present invention will be described based on an embodiment of the present invention, but the present invention is not limited to this embodiment.

  First, an image forming apparatus according to the present invention will be described with reference to the block diagram of FIG.

  The image forming apparatus includes an image reading apparatus YS, an image forming apparatus GH, and the like. The image forming unit GH is called a tandem color image forming apparatus, and a plurality of sets of image forming units 10Y, 10M, 10C, and 10K, an intermediate transfer member 6, a secondary transfer unit 7A, a fixing device 9, and a paper feeding unit. 20 etc.

  An image reading device YS including an automatic document feeder 501 and a document image scanning exposure device 502 is installed above the image forming unit GH. The document d placed on the document table of the automatic document feeder 501 is transported by a transport unit, and an image on one or both sides of the document is scanned and exposed by the optical system of the document image scanning exposure device 502, and the line image sensor CCD is scanned. Is read.

  An image signal formed by photoelectric conversion by the line image sensor CCD is subjected to analog processing, A / D conversion, shading correction, image compression processing, and the like in an image processing unit (not shown), and then exposure means 3Y, 3M. , 3C, 3K.

  The image forming unit 10Y that forms a yellow (Y) image includes a charging unit 2Y, an exposure unit 3Y, a developing device 4Y, a primary transfer unit 7Y, and a cleaning unit 8Y around the photosensitive drum 1Y. The image forming unit 10M that forms a magenta (M) color image includes a charging unit 2M, an exposure unit 3M, a developing device 4M, a primary transfer unit 7M, and a cleaning unit 8M around the photosensitive drum 1M. An image forming unit 10C for forming a cyan (C) color image includes a charging unit 2C, an exposure unit 3C, a developing device 4C, a primary transfer unit 7C, and a cleaning unit 8C around the photosensitive drum 1C. The image forming unit 10K that forms a black (Bk) image includes a charging unit 2K, an exposure unit 3K, a developing device 4K, a primary transfer unit 7K, and a cleaning unit 8K around the photosensitive drum 1K. The charging unit 2Y and the exposure unit 3Y, the charging unit 2M and the exposure unit 3M, the charging unit 2C and the exposure unit 3C, and the charging unit 2K and the exposure unit 3K constitute a latent image forming unit.

  The developing devices 4Y, 4M, 4C, and 4K include a two-component developer including yellow (Y), magenta (M), cyan (C), and black (K) toner having a small particle diameter and a carrier.

  The intermediate transfer body 6 is wound around a plurality of rollers and is rotatably supported.

  The fixing device 9 heats and presses the toner image on the recording paper P (recording material) at a nip portion formed between the fixing roller 91 incorporating the halogen lamp and the pressure roller 92 to fix the toner image.

  Each color image formed by the image forming units 10Y, 10M, 10C, and 10K is sequentially primary-transferred onto the rotating intermediate transfer body 6 by the primary transfer means 7Y, 7M, 7C, and 7K, and color image synthesis is performed. A toner image is formed.

  The recording paper P stored in the paper feed tray 21 is separated and fed by the paper feed roller 22 of the paper feed means 20, passes through a plurality of paper feed rollers 23, and enters the stopped registration roller 24. Paper is fed. Therefore, the roller is temporarily stopped, and the registration roller 24 starts to rotate at the timing when the positional relationship between the leading end and the toner image on the intermediate transfer member 6 accurately coincides, and is fed to the secondary transfer unit 7A for recording. A color image is secondarily transferred onto the paper P. The recording paper P to which the color image has been transferred is heated and pressurized by the fixing device 9 and the color toner image on the recording paper P is fixed. Thereafter, the sheet is sandwiched between the sheet discharge rollers 25 and placed on the sheet discharge tray 26 outside the apparatus.

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

  Although the above is an image forming apparatus that forms a color image, an image forming apparatus that forms a monochrome image may be used.

  Next, the fixing device 9 according to the present invention will be described based on the enlarged sectional view of FIG. The fixing device 9 is a heat roller fixing type fixing device.

  The fixing roller 91 (fixing member) covers a halogen heater H (heating means) built in the center, a core metal 91A containing the halogen heater H, an elastic layer 91B covering the core metal 91A, and an elastic layer 91B. And a surface layer 91C. The core metal 91A is made of a metal such as aluminum or iron, and is formed in a cylindrical shape. The elastic layer 91B is made of silicone rubber or fluorine rubber. The surface layer 91C is made of PFA (perfluoro resin) or PTFE (tetrafluoroethylene resin), and is coated or covered with a tube. Then, it contacts the toner image on the recording paper P at the time of fixing.

  The pressure roller 92 includes a cored bar 92A, an elastic layer 92B that covers the cored bar 92A, and a surface layer 92C that covers the elastic layer 92B. The core metal 92A is made of a metal such as aluminum or iron, and is formed in a cylindrical shape. The elastic layer 92B is made of silicone rubber or fluorine rubber. The surface layer 92C is made of PFA or PTFE, and is coated or covered with a tube. The pressure roller 92 is biased by a biasing member (not shown) and presses the fixing roller 91 from below.

  The separation claw 93 is made of a heat-resistant resin such as PI (polyimide), has a sharp tip, and is in pressure contact with the outer peripheral surface of the fixing roller 91.

  With the above configuration, when the fixing roller 91 heated by the halogen heater H is driven by a motor (not shown) to rotate clockwise, the pressure roller 92 is driven to rotate counterclockwise. Further, since the pressure roller 92 is in pressure contact with the fixing roller 91, a nip portion N is formed between the fixing roller 91 and the pressure roller 92, and the toner image is transferred by the image forming apparatus as shown in FIG. The recording paper P is nipped and conveyed at the nip portion N, heated and pressurized, and the toner image is fixed. Further, the leading end portion of the recording paper P attached to the fixing roller 91 is peeled off by the separation claw 93.

  When a large number of recording materials are fixed by using such a fixing device 9, the surface of the fixing roller 91 is finely formed by the edge in the width direction of the recording paper P, the paper dust generated from the recording paper P, the pressure contact of the separation claw 93, and the like. Nails and irregularities occur. As a result, the gloss of the image of the recording paper P fixed on the fixing roller 91 where the wrinkles or dents are generated differs from the other parts due to the influence of wax in the toner or oil applied to the surface of the fixing roller 91. There arises a problem that the difference in gloss is easily noticeable. In this case, it is inconspicuous in a line drawing, but is easily noticeable in a solid image such as a photographic image.

  Therefore, the fixing device 9 includes a polishing member that contains abrasive grains and contacts the fixing roller 91, and the outer peripheral surface of the fixing roller 91 is polished by the polishing member.

  In this case, the polishing member is a film 94 containing abrasive grains. When the film 94 comes into contact with the outer peripheral surface of the fixing roller 91, the fixing roller 91 is polished and wrinkles and the like are removed and uniformized.

  The film 94 is made of PE (polyethylene), for example, and is coated with aluminum oxide abrasive grains. The grain size of the abrasive grains is desirably 3 μm (# 4,000) or more and 12 μm (# 1,200) or less.

  Then, the film 94 wound around the original winding shaft 95 is brought into contact with the fixing roller 91 by the pressing roller 96 during the rotation of the fixing roller 91 and is taken up by the winding shaft 97. As a result, the outer peripheral surface of the fixing roller 91 is polished, so that wrinkles are removed and uniformized.

  The time when the film 94 abuts against the fixing roller 91 may be always abutment. Usually, the pressing roller 96 is separated from the film 94 and driven by a cam or the like every predetermined number of fixing sheets. The roller 96 may press the film 94 to bring the film 94 into contact with the fixing roller 91. Further, only when a jam occurs in the fixing device 9, the fixing roller 91 may be polished by bringing the film 94 into contact with the fixing roller 91.

  Further, as in the fixing device shown in FIG. 3, a brush roller 99 may be used as the polishing member. In FIG. 3, the fixing roller 91, the pressure roller 92, and the separation claw 93 are the same as those shown in FIG.

  The brush roller 99 is made by implanting nylon fibers 99A kneaded with aluminum oxide abrasive grains on a roller 99B made of metal. Then, like the film 94, it is brought into contact with the fixing roller 91 as appropriate and rotated in the direction of the arrow. This also provides the same effect as the film 94. The grain size of the abrasive grains is desirably 9 μm (# 2,000) or more and 30 μm (# 600) or less.

Next, the recording paper is fixed by a fixing device having the film 94 shown in FIG. 2 as an abrasive member, a fixing device having the brush roller 99 shown in FIG. 3 as an abrasive member, and a fixing device not having an abrasive member. An experiment for comparing and confirming the number of sheets in which the gloss difference occurs is described below.
(1) Experimental conditions a. Example 1
・ Film: PE film coated with aluminum oxide abrasive grains ・ Abrasive grain size: 12 μm (# 1200)
・ Nip width between film and fixing roller: 3mm
・ Contact time: Contact for 20 seconds every 10,000 fixed sheets ・ Film feed speed: 3 mm / 20 sec
b. Example 2
・ Brush roller: 610 nylon fiber kneaded with aluminum oxide abrasive grains is implanted in a roller made of metal. ・ Grit grain size: 30 μm (# 600) Content 20%
-Fiber diameter: 0.45 mm
・ Fiber length: 3mm
・ Fiber density: 500 / inch ²
・ Roller diameter: 20mm
・ Fiber bite: 1mm
・ Rotation speed of brush roller: 180rpm
Contact timing: Contact for 10 seconds every 10,000 fixed sheets c. Fixing roller and roller diameter: 50 mm
・ Surface layer: PFA coating thickness 30μm
d. Separation nails / surface: PFA coating / contact surface load: 15 gf
e. Gloss measuring instrument BYK-Gardner 75 ° gloss meter f. Evaluation The separation claw is brought into contact with the fixing roller, and the gloss streak generated in the A4 size solid image is measured with a gloss measuring instrument and evaluated at that level. (2) Experimental results a. Experimental results: shown in Table 1.

b. Evaluation criteria ○ ・ ・ ・ Gloss difference of less than 8 Δ ・ ・ ・ Gloss difference of 8 or more and less than 10 × ・ ・ ・ Gloss difference of 10 or more (3) Consideration In Examples 1 and 2, 500,000 sheets were fixed. However, no gloss streak was generated.

  On the other hand, when no polishing member was provided, the gloss was poor when the number of sheets reached 250,000. In addition, although 200,000 sheets can be allowed for line drawings, the maximum quality of photographic images and the like is 50,000 sheets.

  The above is a configuration in which the wrinkles attached to the fixing roller of the fixing device of the heat roller fixing method are removed by a film or a brush roller to make it uniform, but it is attached to the fixing belt (fixing member) of the fixing device of the belt fixing method. It is also possible to remove the wrinkles with a film or a brush roller and make them uniform, using a polishing member.

  As a belt-fixing type fixing device, for example, as is well known, an endless fixing belt stretched around a heating roller incorporating a halogen heater and the like and circulated and driven, and a fixing roller via a fixing belt are provided. This is a system that has a pressure roller that pressurizes and heats and pressurizes the recording paper onto which the toner image is transferred at the nip formed by the fixing belt and the pressure roller while sandwiching and transporting the recording paper.

  Further, there may be three or more rollers that stretch the fixing belt.

  Further, the above-described pressing roller 96 may be used instead of the tension roller that applies tension to the fixing belt.

  Furthermore, a belt may be used instead of the pressure roller for forming the nip portion on the back side of the recording material on which the toner is not transferred.

1 is a configuration diagram of an image forming apparatus. It is an expanded sectional view of a fixing device using a film as an abrasive member. It is an expanded sectional view of a fixing device using a brush roller as an abrasive member.

Explanation of symbols

9 Fixing Device 91 Fixing Roller 92 Pressure Roller 93 Separation Claw 94 Film 99 Brush Roller N Nip Portion P Recording Paper

Claims (8)

A fixing member that rotates and contacts the toner image on the recording material;
A polishing member containing abrasive grains of a predetermined particle size and abutting against the fixing member;
A fixing device comprising: The fixing device according to claim 1, wherein the fixing member is a fixing roller including a heating unit. The fixing device according to claim 1, wherein the fixing member is a fixing belt stretched around a plurality of rollers. The fixing device according to claim 1, wherein the polishing member is a film coated with predetermined abrasive grains. The fixing device according to claim 1, wherein the polishing member is a brush roller in which fibers containing predetermined abrasive grains are implanted. The fixing device according to claim 1, wherein the polishing member contacts the fixing member every predetermined number of fixing sheets. The fixing device according to claim 1, wherein the abrasive grains contained in the polishing member have a particle size of 3 μm or more and 30 μm or less. An image forming apparatus comprising the fixing device according to claim 1.

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