JP2007328168A - Fixing device and electrophotographic device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing device capable of detecting the winding state of paper round a heating roll by use of the conventional paper conveyance sensor without adding an expensive component and an expensive mechanism. <P>SOLUTION: A winding preventing member 18 is provided on the outside of a paper conveyance path 14 in a paper ejecting direction from a paper holding and pressuring position 23, and controls a gap G5 between the heating roll 12 and the winding preventing member 18, so that the paper P is buckled multiply and accumulated at the upper part of a paper sensor arm 19, and then the paper sensor arm 19 is rotated by the buckling force of the paper P to press the paper conveyance sensor 10 in the paper conveyance path 14. Thus, the winding of the paper is detected. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fixing device having a winding detection device and an electrophotographic apparatus using the same.

  A conventional fixing device of an electrophotographic apparatus will be described with reference to FIGS. The fixing device 8 includes a heating roll 12 having a heating body H1 therein, a pressure roll 13 and a paper peeling air nozzle 15. In a normal printing state, the sheet having the unfixed toner T3 transferred onto the upper surface of the sheet P is conveyed from the upstream side, and is sandwiched between the heating roll 12 and the pressure roll 13 facing each other, and is heated under pressure to fix the toner image. The After that, pressure air is sprayed from the paper peeling air nozzle 15 to the paper leading edge, and the paper leading edge Pt is peeled from the heating roll 12. However, when the paper state is bad or the pressure air peeling performance is bad, the paper P is wound around the heating roll 12 without being peeled off. In this case, detection by the paper transport sensor 10 in the paper transport path 14 is impossible, and forgetting to remove the paper is an obstacle to quick paper jam repair.

  Patent Document 1 discloses a configuration in which paper winding around a heating rotator is detected by a cantilever and optical detection means, but there is a problem that the configuration becomes complicated and a separate detection means is provided, resulting in an increase in cost. .

JP 2003-114588 A

  An object of the present invention is to make it possible to detect a state in which a sheet is wound around a heating roll in a fixing device with a simple configuration and to prevent forgetting to remove the sheet remaining in the fixing device when the heating roll is wound.

  In order to achieve the above object, the present invention uses a conventional paper conveyance sensor in the paper conveyance path so that the presence of the paper when the paper is wound around the heating roll can be detected by the sensor. A sheet winding prevention member disposed outside the sheet conveyance path in the sheet discharge direction with a certain clearance from the heating roll in the fixing device is provided, and the sheet conveyance sensor in the sheet conveyance path is turned on. . Further, in order to ensure the detection of the wound paper, this is achieved by providing a displaceable paper sensor arm in the vicinity of the paper transport path facing the paper transport sensor.

  As described above, according to the present invention, it is possible to detect a paper jam and a paper wrap in the fixing device with a conventional paper conveyance sensor. In addition, detection of paper winding in the fixing device is prevented, so that forgetting to remove the paper is prevented, and quick jam repair is possible.

  A highly reliable winding detection device with a simple configuration was realized by combining mechanical parts and a conventional paper transport sensor.

  An embodiment of a fixing device that employs a fixing paper winding detection device of an electrophotographic apparatus embodying the present invention will be described below with reference to the drawings.

  As shown in FIGS. 1 and 2, the fixing device 8 includes a heating roll 12 having a heating body H <b> 1 therein, a pressure roll 13, and a paper peeling air nozzle 15. In a normal printing state, the sheet P having the unfixed toner T3 transferred onto the upper surface of the sheet P is conveyed from the upstream side, and is fixed by being pressed and heated by the opposing heat roller 12 and pressure roller 13. When the pressure P is blown from the paper peeling air nozzle 15 to the paper and the paper P is peeled off from the heating roll 12, the heating is performed when the paper state is bad or the paper peeling air nozzle 15 is bad. When the paper is caught in the roll 12, the paper conveyance sensor 10 in the paper conveyance path 14 cannot recognize the state in which the paper P is wound on the heating roll 12, which causes forgetting to take out the paper. ing.

  As shown in FIGS. 3 and 4, the wrapping prevention member 18 has a gap G <b> 5 (0.1 to 0.1) between the heating roll 12 and the outer side of the paper conveyance path 14 in the paper discharge direction from the pressure position 23 of the heating roll 12. 2 mm) is fixed to the support column 20 with screws. When the paper is wound around the heating roll 12, the paper leading end Pt of the paper P hits the wrapping preventing member 18, and the paper leading end Pt stops, but the heating roll 12 and the pressure roll 13 are immediately brought about by inertia. The paper P is transported without stopping, so that the paper P accumulates under the anti-winding member 18 while buckling the paper P multiple times. The paper P that has been buckled several times is accumulated on the upper part of the paper sensor arm 19 disposed at the lower part of the winding preventing member 18, and the paper sensor arm 19 is rotated into the paper conveyance path 14 by the buckling force of the paper P. Then, by pressing the leading end portion 10t of the sheet conveyance sensor 10 in the conveyance path 14, the sheet conveyance sensor 10 is turned on and the sheet wound around the heating roll 12 in the fixing device 8 can be detected.

  In this embodiment, the paper sensor arm is used. However, the paper conveyance sensor can be operated by the bent paper itself by adjusting the installation position of the wrapping prevention member.

It is a schematic diagram showing a fixing device of a conventional electrophotographic apparatus. It is sectional drawing which shows the fixing device of the conventional electrophotographic apparatus. FIG. 6 is a schematic diagram illustrating an example of a winding preventing member of the fixing device according to the present invention. FIG. 6 is a schematic diagram illustrating an example of a winding preventing member of the fixing device according to the present invention.

Explanation of symbols

8 is a fixing device, P is paper, Pt is paper leading edge, T3 is unfixed toner, H1 is a heating element, G5 is a gap between the heating roll and the wrapping prevention member, 10 is paper feeding sensor, and 10t is paper feeding sensor tip. , 12 is a heating roll, 13 is a pressure roll, 14 is in the conveyance path, 15 is a paper peeling air nozzle, 18 is a wrapping prevention member, 19 is a paper sensor arm, 20 is a column, and 23 is a pressure position. is there.

Claims (5)

An electrophotographic apparatus having a pair of heating rolls and pressure rolls that sandwich and convey a sheet, heat and fix toner on the sheet and feed the sheet to a sheet conveyance path, and a sheet conveyance sensor that detects sheet conveyance in the sheet conveyance path In the fixing device of
A fixing device for detecting the presence or absence of a sheet wound around a heating roll by using a sheet conveyance sensor for detecting a sheet in the sheet conveyance path. A winding preventing member for separating the paper wound around the heating roll from the heating roll is provided adjacent to the vicinity of the surface of the heating roll on the paper exit side, and the peeled wound paper is detected by the paper transport sensor. The fixing device according to claim 1. 2. A paper sensor arm that is displaceable by a peeled-off wound paper is provided in the vicinity of the winding preventing member, and is disposed at a position where the displacement of the paper sensor arm is detected by a paper transport sensor. 3. The fixing device according to 2. The fixing device according to claim 1, wherein the sheet is peeled off from the heating roll by blowing pressure air. An electrophotographic apparatus comprising the fixing device according to claim 1.

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