JP2007199596A - Electrophotographic fixing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that when a roughing roller coming into contact with a surface layer of a fixing roller is provided, the fixing roller surface layer is damaged and the effect of the roughening roller is not exhibited since dirt such as a toner and paper powder sticks on the roughening roller during fixation processing and the problem that roughening of a fixing roller becomes not constant from the beginning as surface roughness of the surface layer of the roughening roller varies. <P>SOLUTION: The roughening roller is provided with an attaching/detaching mechanism and then the roughing roller is always put away from the fixing roller during fixation processing and pressed against the fixing roller during non-fixation processing when necessary to keep the surface roughness of the fixing roller surface layer constant, thereby making it hard for foreign matter such as the toner and the paper powder to stick during the fixation processing. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention has an image forming means for forming an unfixed toner image on a recording material using an electrophotographic process or the like, and a fixing device for thermally fixing the unfixed toner image on the recording material. In addition, the present invention relates to an electrophotographic fixing device in an image forming apparatus such as a copying machine, a facsimile, or a printer that obtains a hard copy.

  As a fixing device in an electrophotographic image forming apparatus, a heat roller pair type fixing device using a fixing roller and a pressure roller is generally used. The fixing roller has an elastic layer made of silicone rubber or fluororubber on the surface layer of Al or iron core metal, and its durability is a problem. In particular, there has been a problem that the surface layer of the fixing roller is gradually roughened due to an attack caused by paper passing, paper dust, offset toner, and the like.

In order to eliminate the unevenness of the surface roughness, it is considered to use a technique (refer to Patent Document 1) in which a roughening member is brought into contact with the fixing roller in order to keep the roughness of the portion where the thermistor abuts constant. It is done. However, in this contact of the rubbing member, the feed speed of the rubbing member is fixed or very slow with respect to the rotation of the fixing roller, and the same position of the rubbing member continues to hit the fixing roller. As a result, streak-like roughness occurs in the rotation direction of the fixing roller, which appears as uneven gloss on the recording paper image after fixing.
Japanese Unexamined Patent Publication No. 04-213482

  Further, when the same size print paper is continuously passed through such a fixing device, the surface layer of the fixing roller (heat roller) corresponding to the portion through which the edge of the paper passes is gradually roughened, and the surface roughness is reduced. Since a region higher than the surroundings is generated, the problem of appearing as gloss unevenness on the recording paper image after fixing has occurred by the inventors' investigation.

  In order to solve this problem, an attempt was made to make the rubbing member of the fixing roller into a roller shape that can be driven and rotated with respect to the fixing roller. As a result, the above problem could be solved by providing a roughening roller that uniformly roughens the surface of the fixing roller.

  However, if a roughening roller in contact with the fixing roller is provided for the purpose of keeping the surface of the fixing roller uniform, dirt such as toner and paper dust will adhere to the roughing roller during printing, resulting in damage to the surface of the fixing roller. In addition, there is a problem that the roughening effect of the roughening roller is not exhibited.

  The above-described problems are solved by the following fixing device according to the present invention.

(1) A rotatable fixing member, a pressure member in contact with the fixing member, and a roughening roller disposed so as to be detachable from the fixing member and roughening the surface layer of the fixing member. In the fixing apparatus for electrophotography (2), the roughening process is performed by performing a roughening process by separating the fixing member from the fixing member and in contact with the rotating fixing member during the non-fixing process. An electrophotographic fixing apparatus, which is performed when recording paper is not in contact with a fixing member during printing.

  (3) The electrophotographic fixing device according to (1) or (2), wherein a roughening process is performed at the end of the printing operation.

  (4) The electrophotographic fixing device according to any one of (1) to (3), wherein the fixing member performs a roughening process during warm-up or standby.

  According to the above fixing device according to the present invention, when the roughening roller for keeping the surface state of the fixing roller uniform is used, it is possible to prevent the dirt from adhering to the roughening roller. As a result, it is possible to stably maintain the surface roughness of the fixing roller for a long period from the beginning while preventing foreign matters adhering to the roughening roller on the surface of the fixing roller.

  Hereinafter, the present invention will be described more specifically with reference to examples. Although these examples are examples of the best mode of the present invention, the present invention is not limited to these examples.

<Fixing device>
FIG. 1 is an enlarged view of a fixing device according to an embodiment of the present invention.

  The fixing roller 91 is formed by molding 1.0 mm of a silicone rubber having a rubber hardness of 20 ° (JIS-A1 kg load) as an elastic layer on a hollow cored bar made of Al having an outer diameter of φ68 mm and covering the surface with a fluororesin having a thickness of 30 μm An outer diameter of 70 mm was used.

  The fixing roller 91 has a halogen heater 95 as a heating source inside, and is adjusted to 160 ° C. by a temperature sensor (not shown) and a temperature control circuit (not shown).

  The pressure roller 94 is formed by molding 1.0 mm of silicone rubber with a rubber hardness of 20 ° (JIS-A1 kg load) on a hollow cored bar made of Al with an outer diameter of φ48 mm and covering the surface with a fluororesin with a thickness of 30 μm. An outer diameter of 50 mm was used.

  The pressure roller 94 is pressed against the fixing roller 91 with a pressure of 80 kgf.

  As a roughening roller, a surface of a SUS roller having an outer diameter of φ20 mm was blasted to use a roughening roller 99 having a surface roughness of 25 to 30 μm.

  The roughening roller 99 has a motor in a support portion, and can be attached to and detached from the fixing roller 91. When removed (FIG. 2), the fixing roller 91 is completely separated from the surface layer. Further, at the time of wearing (FIG. 1), the fixing roller 91 is pressurized with a total pressure of 10 kgf using springs of 5 kg at both ends of the roller, and is driven by the rotation of the fixing roller 91.

  Although the above-described roller-shaped roughening roller is used this time, the surface layer may be roughened by chemically treating the abrasive grains that have been bonded.

  The counter counts the number of sheets that pass when recording paper is passed. This counter is interlocked with the controller, and serves as a reference value for determining the operation time of the fusing roller 91 surface roughening.

  The surface roughness of the roughening roller 99 substantially corresponds to the upper limit of the surface roughness of the fixing roller 91 when the fixing roller 91 is roughened, and the surface roughness of the fixing roller 91 is set to a predetermined value by setting the surface roughness and the applied pressure to predetermined values. It is possible to make the surface roughness range a predetermined range.

  From the upstream side, the pressure roller 94, the cleaning member 98, and the roughening roller 99 are brought into contact with the fixing roller 91 in this order, and foreign matter generated from the recording paper passing between the endless belt 92 and the fixing roller 91 is cleaned by the cleaning member 98. And makes it difficult to turn to the roughening roller 99. Further, in addition to the above configuration, the rough roller 99 is separated from the fixing roller 91 during the fixing process, thereby preventing the adhesion of dirt.

  Next, the operation of this fixing device will be described.

  First, when the surface of the fixing roller 91 reaches a predetermined set temperature by the heating of the halogen lamp 95 and a start signal for an image forming operation (such as a copying operation or a printing operation) in the image forming apparatus is received, recording is performed in the image forming apparatus. The paper P is conveyed from the paper feed deck.

  In the image forming unit, a toner image is transferred and formed on the recording material P, and the recording material P is conveyed to the fixing device. In synchronization with the start of the image forming operation, the fixing roller 91 starts to rotate in the direction of the arrow in the drawing, and at the same time, the pressure roller 94 follows the fixing roller 91 and starts to rotate in the direction of the arrow in the drawing.

  Due to the rotation of the fixing roller 91, the pressure roller 94 is driven to rotate with respect to the fixing roller 91, and the toner image is fixed to the recording material P by passing the recording material P therebetween.

  In the present embodiment, an example is shown in which the interval during which the recording paper passes is longer than the time considering the attachment / detachment of the roughening roller 99 and the roughening operation is possible during that time. The vandalizing operation will be described with reference to FIG.

  In a fixing device with a process speed of 100 mm / s and 10 ppm, the time required for the entire area of one A4R size recording paper to pass between the nip formed by the fixing roller 91 and the pressure roller 94 during a printing operation. Is about 3 seconds. The time from the completion of the passage to the arrival of the next recording paper was about 3 seconds. Immediately after the recording paper passes, the roughening roller 99 performs a landing operation on the fixing roller 91 and has a mechanism for separating from the fixing roller 91 at the moment when the next recording paper reaches the fixing nip. By repeating this operation for each recording paper, it becomes possible to keep roughing, and the surface roughness of the fixing roller 91 can be kept uniform. As a result, there was almost no dirt on the surface of the roughening roller 99, and the surface roughness could be kept between 25 and 30 μm from the beginning.

  This embodiment is a method of performing a roughening process between the warm-up of the fixing device and the standby. The vandalizing operation will be described with reference to FIG.

  When the operation of the fixing device was started from the beginning, a warm-up operation of about 5 minutes was required. During this warm-up, the surface of the fixing roller 91 is roughened by pressing the roughening roller 99 against the fixing roller 91 and rotating the fixing roller 91. Further, at the time of standby when the printing operation is not performed after the warm-up, the roughening time is calculated from the number of paper passing from the relationship diagram of the number of paper passing and the required roughening time in FIG. When a printing operation is entered in the middle of the roughening operation, the count of the number of sheets passed for the roughing time is subtracted, the roughening operation is interrupted, and the printing operation is started.

  After the printing operation is completed, the roughening operation is performed in the same way at the time of the post-rotation and the pre-rotation until the next printing operation, and the count of the number of passing sheets for the roughing time is subtracted.

  By performing this operation, the surface roughness on the fixing roller 91 is almost completely uniform when the standby state for the fixing roller 91 longer than the required roughening time is entered between the printing operations. It was confirmed. At this time, the surface layer of the roughening roller 99 was hardly contaminated, and the surface roughness of the fixing roller 91 could be kept between 25 and 30 μm from the beginning.

  FIG. 3 is a correlation graph between the roughening time and the surface roughness of the fixing roller surface layer according to the present invention.

  FIG. 4 is a graph showing the relationship between the number of sheets passing and the surface roughness of the fixing roller according to the present invention.

  Examples 1 and 2 are typical embodiments of the present invention, and actually vary depending on the fixing device and the environment. Therefore, it is necessary to create a table according to the implementation conditions and determine the roughening time. is there.

  In the present embodiment, a roller-shaped pressing member is used for the pressing unit, but the pressing unit is not limited to a roller, and may be used in an endless belt system.

(Industrial applicability)
The roughness of the surface layer of the roughening roller 99 changes due to print paper, paper dust, dirt, and the like. In the present invention, since the foreign matter such as toner and paper dust does not adhere to the roughening roller 99, the surface roughness of the roller surface layer can always be returned to a constant level.

FIG. 3 is a cross-sectional view of the fixing device when the roughening roller is attached according to the first embodiment of the present invention. FIG. 3 is a cross-sectional view of the fixing device when the roughening roller is removed according to the first embodiment of the present invention. 6 is a correlation graph between the roughening time and the surface roughness of the surface layer of the fixing roller according to the present invention. FIG. 4 is a relationship diagram between the number of sheets passing and the surface roughness of the fixing roller according to the present invention. FIG. 2 shows the relationship between the roughening time required for smoothing the surface roughness on the roller with respect to the number of sheets to be passed, obtained from FIGS. FIG. 6 is a diagram illustrating a timing of a vandalizing operation according to a state of the fixing device according to the present invention. FIG. 6 is a diagram illustrating a timing of a vandalizing operation according to a state of the fixing device according to the present invention.

Explanation of symbols

9 Fixing section 91 Fixing roller 94 Pressure roller 95 Halogen heater 98 Cleaning web 99 Roughening roller

Claims (4)

  A rotatable fixing member, a pressure member in contact with the fixing member, and a roughening roller that is detachably disposed on the fixing member and roughens the surface of the fixing member, and the roughening roller fixes during the fixing process. An electrophotographic fixing device that performs a roughening process by contacting a rotating fixing member that is separated from a member and in a non-fixing process.   2. The electrophotographic fixing apparatus according to claim 1, wherein the roughening process is performed when the recording paper is not in contact with the fixing member during printing.   3. The electrophotographic fixing apparatus according to claim 1, wherein a roughening process is performed at the end of the printing operation.   4. The electrophotographic fixing device according to claim 1, wherein the fixing member performs a roughening process during warm-up or standby.

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