JP2005157032A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing apparatus which realizes a safe and stable high image quality without spoiling operability by preventing an accident even in a fixing unit using a metallic film having a relatively high heat capacity, even in the case of a short circuit and to provide an image forming apparatus using the same. <P>SOLUTION: In the fixing unit having a paper ejection guide which cannot be opened/closed when being attached to an apparatus body and can be opened/closed when being alone, a handle (a finger hook or the like) which is operated when opening/closing sets a stopper position of the guide to a press-in side with respect to the fulcrum of rotation, so that breakage caused to erroneous operation at the time of attachment/detachment is prevented. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus such as a copying machine or a printer, and more particularly to an image forming apparatus in which a fixing unit is detachable from an image forming apparatus main body.

  Many printers and copiers form an image by an electrophotographic recording method. In this electrophotographic recording method, a toner image is transferred to a recording medium, and heat and pressure are applied to the recording medium. The image is fixed.

  Conventionally, a heat roller system has been used as a fixing device for fixing the toner image. This system is based on a metal roller with a heater inside and a pressure roller with elasticity that presses against it, and a recording medium as a heated member is introduced into the nip portion of the roller pair for clamping. The toner image is heated and pressure-fixed by being conveyed and passed.

  However, in such a heat roller type fixing device, since the heat capacity of the roller is large, it takes a very long time to raise the roller surface to the fixing temperature. For this reason, in order to execute the image output operation promptly, there is a problem that the roller surface must be temperature-controlled to a certain temperature even when the apparatus is not used.

  Therefore, in order to solve the above problems, a film heating type heating apparatus that heats and fixes a film has been proposed (JP-A-4-44075, etc.).

  This film heating type fixing device is usually arranged with a heat resistant film of book meat, a heating element (heater) arranged to be fixedly supported on one side of the film, and a heater on the other side facing the heater. The pressure roller includes a heater and a recording medium as a member to be heated, which is in close contact with the heater via a film.

  When this is used as a fixing device, a recording medium carrying a toner image is introduced and passed through a pressure nip formed by pressure contact between a heater and a pressure roller with the film interposed therebetween. As a result, the visible image carrier surface of the recording medium is heated by the heater through the film, imparts thermal energy to the unfixed image, and the toner is softened and melted to heat and fix the image.

In the film heating type fixing device, since a low heat capacity heater can be used as a heater, it is possible to save power and shorten the wait time as compared with the conventional heat roller type and belt heating type devices.
JP-A-4-44075

  In the above-mentioned film heating type heat fixing apparatus using a polyimide film having a very small heat capacity, there is a limit in fixing property, glossiness, etc., particularly in a high speed machine or an image forming apparatus that needs to fix a color image. It is conceivable to use a metal film having a large thickness. However, when a metal film is used, it is conceivable that power supplied to the fixing device for some reason may leak to the metal film, and this countermeasure must be taken.

  The present invention solves the above-described problems, and the object of the present invention is to prevent accidents even in the case of a fixing device using a metal film having a relatively large heat capacity, and in the event of an electric leakage, thereby improving operability. It is an object of the present invention to provide a fixing device that realizes a safe and stable high image quality without loss and an image forming apparatus using the same.

  In order to achieve the above object, a typical configuration according to the present invention includes an image forming unit that forms an image on a recording material, a fixing unit that heat-fixes an image formed on the recording material, and a recording material that has passed through the fixing unit. A fixing unit having a guide unit for guiding the image forming apparatus, wherein the fixing unit is detachable from the main body of the image forming apparatus. When the fixing unit is attached to the image forming apparatus main body, the guide unit is restricted from moving to a non-guide position, and the fixing unit is attached to the image forming apparatus main body. When the guide unit is removed from the guide unit, the guide unit can be moved to a non-guide position, and the guide unit is provided with a lever for operation by a user. And it is provided and the fixing unit longitudinal end side at the top of the guide portion.

  Even if an AC current flowing through the metal film for some reason flows through the metal film, the metal film is not touched.

  At the same time, with respect to the rotation fulcrum of the handle used when the guide member is opened and closed, even if an attempt is made to open the guide member while the fixing device is mounted on the image forming apparatus main body, the direction in which pressure is applied to the image forming apparatus main body side. By disposing in this way, the user is made aware of the erroneous operation and the guide member and the like are prevented from being damaged by the erroneous operation.

  Next, an embodiment of an image forming apparatus using the fixing device according to the present invention will be described with reference to the drawings.

  1 is a cross-sectional view of the main part of the fixing device, FIG. 2 is a cross-sectional view of the main part of the fixing device during jam processing, and FIG. 3 is a diagram schematically showing the configuration of the image forming apparatus according to an embodiment of the present invention. 4 is a detailed cross-sectional view of main parts of the fixing device, FIG. 5 is a side external view of the fixing device, FIG. 6 is a cross-sectional view of a metal film, and FIG. 7 is a perspective view showing main components.

  The image forming apparatus according to the present embodiment is a full-color image forming apparatus that employs an electrophotographic system, and is arranged on a substantially straight line in a substantially vertical direction, as shown in FIG. The two process stations 1a to 1d and a conveyance path for conveying the sheet S are provided.

  Each of the process stations 1a to 1d includes at least photosensitive drums 2a to 2d for carrying a latent image, and the photosensitive drums 2a to 2d are uniformly charged around the photosensitive drums 2a to 2d. Charging rollers 3a to 3d, exposure devices 4a to 4d for irradiating the photosensitive drums 2a to 2d with laser light to form a latent image, and latent images formed on the photosensitive drums 2a to 2d Developing means 5a to 5d for developing the toner with the corresponding color (magenta, cyan, yellow, black) toner to visualize the image, and cleaning devices 6a to 6d for removing the residual toner on the photosensitive drums 2a to 2d. Has been placed.

  Each of the developing units 5a to 5d includes developing sleeves 50a to 50d for carrying toner. Each of the developing sleeves 50a to 50d is supported at a predetermined distance from the corresponding photosensitive drum 2a to 2d, and a developing bias is applied between the photosensitive drums 2a to 2d and the developing sleeves 50a to 50d during development. The

  The intermediate transfer belt 7 is stretched around a driving roller 8, a driven roller 9, and belt stretching rollers 10 and 11, and is driven to rotate in a direction indicated by an arrow in the drawing.

  The intermediate transfer belt 7 is conveyed along the arrangement direction of the process stations 1a to 1d, and the toner images of the respective colors on the photosensitive drums 2a to 2d are sequentially transferred to the surface of the intermediate transfer belt by primary transfer at each station and are full color. An image is formed.

  On the other hand, the sheets S are stacked and stored in a paper feed cassette 15 provided at the lower part of the apparatus, and are fed one by one from the paper feed cassette 15 by a paper feed roller 16 and fed to a pair of registration rollers 17. The registration roller pair 17 sends the fed sheet S between the secondary transfer roller 12 and the intermediate transfer belt.

  A secondary transfer roller 12 disposed so as to face the driven roller 9 is brought into contact with the lowermost surface of the intermediate transfer belt 7, and the secondary transfer roller 12 passes between the intermediate transfer belt 7 and the intermediate transfer belt 7. The sheet S is nipped and conveyed. A bias is applied to the secondary transfer roller 12 from a high-voltage power supply 13 (bias means), whereby the toner image on the intermediate transfer belt is transferred to the sheet S passing between the secondary transfer roller 12 and the intermediate transfer belt. The next transfer is carried to the fixing unit 18.

  The sheet S on which the toner image is transferred is sent to the fixing device 18. In the fixing device 18, the sheet S is heated and the toner image is fixed on the sheet S. As a result, an image is formed on the sheet S, and the sheet S is discharged from the fixing device 18 to a discharge tray 19 outside the apparatus.

  Here, the detailed structure of the fixing device 18 is shown in FIGS. The heater 101 is fixed to the heater holder 104. As shown in FIG. 5, the film 102 is made of a sleeve-like metal having an elastic layer 102b having a certain heat capacity and a release layer 102c. Next, the element portion 109a of the thermistor 109 installed in the heater holder for measuring the temperature of the film 102 and sending a signal to a CPU (not shown) of the apparatus main body to control the energization to the heater 101 is also the spring portion 109b. It is in contact with the inner surface of the film 102 by the action. The element portion 109a and the spring portion b are configured to be insulated from the film 102 by, for example, a heat resistant resin film. At both ends of the film 102, flanges 110a and 110b made of heat-resistant resin are provided so as to be rotatable simultaneously with the rotation of the film 102. The stage 103 is fixed to pressure members 113a and 113b that are rotatable about a rotation fulcrum 112 provided on the frame 111, and the film 102, the heater 101, and the pressure roller 105 are fixed to the pressure roller 105 by the action of the pressure springs 114a and 114b. The heater holder 104 is pressurized to form a nip n. Since the pressure roller 105 is rotatably fixed by a bearing 115 fixed to the frame 111, the sheet S on which an unfixed image is placed is fixed by the heat generated by the heater 101 and the action of the pressure springs 114a and 114b. The paper discharge upper roller 107 pressed by the action of the paper discharge spring 118 fixed to the paper discharge upper guide 121 forms a nip with the paper discharge lower roller 106, conveys the fixed sheet S, and out of the apparatus main body 120. The paper is discharged to the paper discharge tray 19 positioned.

  At this time, as shown in FIG. 1, the paper discharge upper guide 121 is in contact with a positioning portion 120 a provided in the apparatus main body 120 and is positioned. For this reason, it cannot rotate around the rotation center 121c, and the user cannot touch the sleeve 102 in this state as shown in FIG. Therefore, in the case where the fixing unit 18 shown in FIG. 1 is mounted on the main body 120 and is energized, an electric shock may be generated even if a leakage occurs from the heater 101 to the sleeve 102 due to the breakage of the heater 101 for some reason. Can be prevented in advance. At this time, when the levers 121a and 121b are pushed up in the opening direction due to a user's erroneous operation, the lever 121a and 121b are further pressed in the direction in which pressure is applied to the positioning unit 120a. It is preventing.

  Next, when the sheet S is jammed for some reason as shown in FIG. 2, the fixing unit 18 is pulled out from the apparatus main body 120, and the connector 117 is separated from the apparatus main body 120. Blocked. Therefore, by lifting the levers 121a and 121b provided on the paper discharge upper guide 121, the paper discharge upper guide 121 rotates around the rotation center 121c and is opened, so that it is possible to perform jam processing safely and easily. .

(Industrial applicability)
The present invention can be applied not only to an electrophotographic image forming apparatus but also to an electrostatic recording image forming apparatus.

1 is a detailed cross-sectional view of a fixing device in an image forming apparatus according to an embodiment of the present invention. 1 is a detailed cross-sectional view of a fixing device in an image forming apparatus according to an embodiment of the present invention. FIG. 1 is a diagram schematically showing a configuration of an image forming apparatus according to an embodiment of the present invention. 1 is a cross-sectional view of main components of a fixing device and an apparatus main body in an image forming apparatus according to an embodiment of the present invention. It is a side external view of the present invention. It is a section lineblock diagram of a metal film. 1 is a perspective view showing main parts of a fixing device in an image forming apparatus according to an embodiment of the present invention.

Explanation of symbols

S sheet 1a, 1b, 1c, 1d Process station 2 Photosensitive drum 3 Charging roller 4 Paper passing path 7 Intermediate transfer belt 8 Drive roller 9 Drive roller 10 Belt stretch roller 11 Belt stretch roller 12 Secondary transfer roller 13 High pressure Power supply 14a, 14b, 14c, 14d Transfer roller 15 Paper feed cassette 16 Paper feed roller 17 Registration roller pair 18 Fixing device 19 Discharge tray 101 Heater 102 Film 103 Stay 105 Pressure roller 106 Paper discharge lower roller 107 Paper discharge upper roller 108 Conducting member 109 Thermistor 120 Image forming apparatus main body 121 Upper sheet discharge guide 121a, 121b Lever

Claims (5)

An image forming unit that forms an image on a recording material; a fixing unit that includes a fixing unit that heat-fixes the image formed on the recording material; and a guide unit that guides the recording material that has passed through the fixing unit. In the image forming apparatus that is detachable from the image forming apparatus main body,
The guide unit is attached to the fixing unit so as to be movable between a position for guiding the recording material and a non-guide position. When the fixing unit is removed from the image forming apparatus main body, the guide portion can be moved to a non-guide position, and a lever for operation by a user is provided on the guide portion. An image forming apparatus, wherein the lever is provided above the guide portion and at both ends of the fixing unit in the longitudinal direction.   The fixing unit has a power supply connector, and the power supply connector of the fixing unit is connected to a power supply connector of the image forming apparatus main body when the fixing unit is attached to the image forming apparatus main body. The image forming apparatus according to claim 1, wherein the image forming apparatus is disconnected from the power supply connector of the image forming apparatus main body when the image forming apparatus is detached from the image forming apparatus main body.   When the guide unit is moved from the guide position to the non-guide position while the fixing unit is mounted on the image forming apparatus main body, the movement of the lever is restricted by a part of the image forming apparatus main body. The image forming apparatus according to claim 1.   The image forming apparatus according to claim 1, wherein the guide unit includes a roller for guiding the recording material. The image forming apparatus according to claim 1, wherein the fixing unit includes a flexible rotating body having a metal layer.

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