JP2006113173A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus having a fixing device, which is provided with a means for stably peeling a transfer material without scratching a roller. <P>SOLUTION: The image forming apparatus has a fixing device in which an air spraying member is disposed near a heat roller and the position of transfer-material ejection and air is sprayed onto the leading end of a transfer material conveyed accompanying the rotation of the heat roller, thereby peeling the transfer material from the heat roller. The image forming apparatus is provide with an air current regulating member for regulating the flow of the air. Control is exerted such that the leading end of the air flow regulating member is in contact with the surface of the heat roller at a predetermined pressure when the heat roller is not operated, and the leading end is separated from the surface by passing air between the heat roller and the air flow regulating member when the heat roller is operated. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus having a heating roller (or heating belt) type fixing device used for an electrophotographic system such as a copying machine, a printer, and a FAX, and more particularly, includes a means for peeling a transfer material from the heating roller. The present invention relates to an image forming apparatus having a fixing device.

Conventionally, as a transfer material peeling means from a fixing roller (heating roller), a method such as a separation claw or air blowing (for example, see Patent Document 1) is generally known.
JP-A-60-247672

  However, the method of bringing the separation claw into contact with the heating roller has the disadvantage that the heating roller is damaged and appears as image noise on the image. The method by air blowing is the gap between the air jet outlet and the heating roller. To maintain a certain distance, it is necessary to tighten the mounting accuracy and consider errors such as eccentricity of the heating roller. If the mounting accuracy is not maintained, separation may occur or the spraying strength is high. This causes a disadvantage that the transfer material is wound around a heating roller (or a heating belt) that forms a nip portion with the heating roller.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus having a fixing device having means capable of stably peeling a transfer material from a heating roller without damaging the heating roller (or heating belt).

  An air blowing member is arranged in the vicinity of the heating roller and the transfer material discharge, and air is blown to the leading end side of the transfer material conveyed along with the rotation of the heating roller, so that the transfer from the heating roller is performed. In the image forming apparatus having a fixing device for separating the material, an air flow restriction member for restricting the air flow is provided, and when the heating roller is not in operation, the tip of the air flow restriction member is An image forming apparatus, wherein the surface is in contact with the heating roller, and is controlled so that the surface contact is released by passing air between the heating roller and the air flow regulating member during operation.

  By holding the gap between the heating roller and the air flow regulating member by the pressure of the air flow, the gap is kept constant even if the roller is eccentric, and the peeling process can be performed.

  First, an image forming apparatus equipped with the fixing device according to the present invention will be described.

  In the description of the embodiment of the present invention, the technical scope of the present invention is not limited by the terms used in this specification.

  FIG. 1 is a schematic diagram illustrating an example of the overall configuration of the image forming apparatus.

  In FIG. 1, 10 is a photoconductor, 11 is a scorotron charger as charging means, 12 is a writing device as image writing means, 13 is a developing device as developing means, and 14 is for cleaning the surface of the photoconductor 10. A cleaning device, 15 a cleaning blade, 16 a developing sleeve, and 20 an intermediate transfer belt. The image forming unit 1 includes a photoconductor 10, a scorotron charger 11, a developing device 13, a cleaning device 14, and the like. Since the mechanical configuration of the image forming unit 1 for each color is the same, in FIG. Reference numerals are given to configurations of only the (yellow) series, and reference symbols are omitted for the constituent elements of M (magenta), C (cyan), and K (black).

  The arrangement of the image forming means 1 for each color is in the order of Y, M, C, K with respect to the running direction of the intermediate transfer belt 20, and each photoconductor 10 contacts the stretched surface of the intermediate transfer belt 20. The contact point rotates in the same direction as the traveling direction of the intermediate transfer belt 20 and at the same linear speed.

  The intermediate transfer belt 20 is stretched around a driving roller 21, an earth roller 22, a tension roller 23, a static elimination roller 27, and a driven roller 24. The belt unit 3 includes these rollers, the intermediate transfer belt 20, a transfer device 25, a cleaning device 28, and the like. Configure.

  The intermediate transfer belt 20 is driven by rotation of the driving roller 21 by a driving motor (not shown).

  The photosensitive member 10 is formed by forming a photosensitive layer such as a conductive layer, an a-Si layer, or an organic photosensitive member (OPC) on the outer periphery of a cylindrical metal base formed of, for example, an aluminum material, and the conductive layer is grounded. In the state, it rotates counterclockwise as indicated by the arrow in FIG.

  An electrical signal corresponding to the image data from the reading device 80 is converted into an optical signal by the image forming laser, and is projected onto the photoconductor 10 by the writing device 12.

  The developing device 13 is a developing sleeve formed of a cylindrical non-magnetic stainless steel or aluminum material that maintains a predetermined interval with respect to the peripheral surface of the photoconductor 10 and rotates in the reverse direction at the closest position to the rotation direction of the photoconductor 10. 16.

The intermediate transfer belt 20 is an endless belt having a volume resistivity of 10 ⁶ to 10 ¹² Ω · cm. For example, the intermediate transfer belt 20 may be an engineering plastic such as modified polyimide, thermosetting polyimide, ethylene tetrafluoroethylene copolymer, polyvinylidene fluoride, and nylon alloy. It is a semiconductive seamless belt having a thickness of 0.04 to 0.10 mm in which a conductive material is dispersed.

  A transfer unit 25 has a function of transferring a toner image formed on the photoreceptor 10 onto the intermediate transfer belt 20 by applying a direct current having a polarity opposite to that of the toner. As the transfer unit 25, a transfer roller can be used in addition to the corona discharger.

  Reference numeral 26 denotes a transfer roller which can be brought into contact with and released from the earth roller 22 and retransfers the toner image formed on the intermediate transfer belt 20 onto the transfer material P.

  A cleaning device 28 is provided to face the driven roller 24 with the intermediate transfer belt 20 interposed therebetween. After the toner image is transferred to the transfer material P, the intermediate transfer belt 20 has the charge of the residual toner weakened by the neutralizing roller 27 to which an AC voltage superimposed with a DC voltage having the same or opposite polarity as that of the toner is applied. The toner remaining on the peripheral surface is cleaned.

  70 is a paper feed roller, 71 is a timing roller, 72 is a paper cassette, and 73 is a transport roller.

Reference numeral 4 denotes a fixing device, and a transfer material on which the toner image on the intermediate transfer belt 20 has been transferred is not shown and a heating roller 41 heated by a halogen lamp 46, at least one of which is a rotating body having a heat source. The sheet is sandwiched and pressed by a nip portion T formed by a pressure roller 42 pressed by the pressure mechanism. A paper discharge roller 81 discharges the fixed transfer material to a paper discharge tray 82.
B1 is a control unit which is a control unit for each driving unit, image forming process, fixing temperature, air injection timing according to the present invention, and the like.

  Here, the fixing device 4 according to the present invention will be described.

  FIG. 2 is an enlarged cross-sectional view of the periphery of the heating roller and the pressure roller in FIG.

  FIG. 3 is a perspective view of the air flow regulating member.

  2 and 3, reference numeral 5 denotes an air input device which is an air flow regulating member. The air input device 5 includes an air input pipe 50, an air flow restriction plate 51, an air shielding cover 52, a pressing spring 53, a restriction plate support shaft 54, a stopper 55, and the like.

  While the heating roller 41 is rotating, the shutter 57 is opened, and the air blown from the compressor CP flows through the blower space 56 and is ejected from the air input pipe 50 toward the air flow restriction plate 51 through the blower port 501. Thus, the control unit B1 controls.

  The air flow restricting plate 51 is pivotally attached to a restricting plate support shaft 54 supported at both ends by the frame of the fixing device 4, and can be rotated about the restricting plate support shaft 54 as a fulcrum. When the heating roller 41 is rotating, the air flow restriction plate 51 is pushed down to the stopper 55 against the pressing spring 53 by air pressure, and the tip of the air flow restriction plate 51 is The distance d between the heating rollers 41 is maintained. When the heating roller 41 is not rotating, the pressing spring 53 pushes up the air flow restricting plate 51, and the tip end a is in contact with the surface of the heating roller 41 with a predetermined pressure.

  In addition, a fixed (non-rotating) air flow restricting plate made of a material having a predetermined elastic coefficient without a pressing spring or stopper is used. When the heating roller is not rotating, a predetermined pressure is applied. There is also a method in which the tip end a comes into contact with the air pressure, and when it rotates, air is injected to create a deflection of the air regulating plate by the air pressure and keep the interval d (see claim 3).

  The distance d is preferably 0.5 to 2 mm. Moreover, it is preferable that angle (theta) of the front-end | tip part a of the said air flow control board 51 and the nip part center b shall be 10 degrees-50 degrees. The air flow restriction plate 51 is installed so as not to hit the tangent line S of the nip portion T.

  The air shielding cover 52 covers the air flowing portion n in order to prevent air from leaking out from the axial direction as much as possible, and keeps it as confidential as possible.

  FIG. 4 is an enlarged view of the vicinity of the heating roller and the air flow regulating plate for explaining the transfer material separation effect.

In FIG. 4A, when a high-speed air flow S ₁ flows in the vicinity of the transferred transfer material P, a space Z in which the air density decreases is generated, and the heating roller 41 moves in the direction of the air flow S ₁ . A flowing air stream S ₂ is created. As a result, the transfer material P is peeled off from the heating roller 41 as shown in FIG.

  Considering the case of an image forming apparatus capable of producing double-sided printing, the pressure roller 42 is also provided with the air inlet pipe 59, the air blowing port 501, the air flow restriction plate 51 and the like shown in FIG. There is also a method for improving the peeling effect of the transfer material having a plurality of structures.

  In this embodiment, a heating roller and a pressure roller are cited as the two rotating bodies. However, the present invention is also applied to a belt fixing type fixing device in which a heating belt and a pressure roller are combined. You can also.

1 is a schematic diagram illustrating an example of an overall configuration of an image forming apparatus. It is sectional drawing to which the peripheral part of the heating roller and pressure roller in FIG. 1 was expanded. It is a perspective view of an airflow control member. It is an enlarged view of the vicinity of a heating roller and an air flow regulating plate for explaining the separation effect of the transfer material.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming means 4 Fixing device 41 Heating roller 42 Pressure roller 5 Air input device 50 Air input pipe 51 Air flow restriction plate 52 Air shielding cover 53 Pushing spring 54 Restriction plate support shaft 55 Stopper

Claims (5)

An air blowing member is arranged in the vicinity of the heating roller and the transfer material discharge, and air is blown to the leading end side of the transfer material conveyed along with the rotation of the heating roller, so that the transfer from the heating roller is performed. In the image forming apparatus having a fixing device for separating the material, an air flow restriction member for restricting the air flow is provided, and when the heating roller is not in operation, the tip of the air flow restriction member is An image forming apparatus, wherein the surface is in contact with the heating roller, and is controlled so that the surface contact is released by passing air between the heating roller and the air flow regulating member during operation. The image forming apparatus according to claim 1, further comprising a stopper member that restricts a range of a gap between the front end portion of the air flow restriction member and the heating roller when the surface contact is released. The image forming apparatus according to claim 1, wherein a gap between a tip portion of the air flow restriction member and the heating roller is formed by bending of the air flow restriction member. 4. The image forming apparatus according to claim 1, wherein a gap between a front end portion of the air flow restriction member and the heating roller is set to 0.5 to 2 mm. 5. The image forming apparatus according to claim 1, wherein a plurality of the air flow restriction members are provided.

Images