JP2007079411A - Recording paper peeling device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a recording paper peeling device which arbitrarily changes injection directions of a plurality of injection members in accordance with a shape of a fixing member, and also to provide an image forming apparatus including the recording paper peeling device. <P>SOLUTION: The recording paper peeling device is disposed on the paper ejection side of a nip part formed by the fixing member heated by a prescribed heating means and a pressure member pressed to the fixing member, and sprays air to a front end part of a recording paper which is fixed in the nip part and ejected, so as to peel the recording paper from the fixing member. The recording paper peeling device includes: a support member having a passage hole allowing introduced air to pass; and a plurality of injection members having nozzles which are connected to the passage hole and spray air to the front end part of the recording paper, and the plurality of injection members are supported by the support member and are configured so as to be turnable independently of one another. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used in an electrophotographic image forming apparatus such as a copying machine, a printer, a facsimile machine, and a multifunction machine having these functions, and is a recording paper peeling apparatus for peeling a recording paper from a fixing member of a fixing device About.

  In an electrophotographic image forming apparatus such as a copying machine, a printer, a facsimile machine, or a multi-function machine having these functions, the photosensitive member is uniformly charged by a charging unit, and then based on image data by an exposure unit. The photosensitive member is irradiated with light to form an electrostatic latent image, and toner is attached to the electrostatic latent image by developing means to form a toner image. The toner image is transferred onto the conveyed recording paper by the transfer electrode, and the recording paper is electrostatically separated from the photosensitive member by the separation electrode, and then the toner image is pressed and heated by the fixing means and fixed on the recording paper. Discharged outside. Further, the transfer residual toner remaining on the photoconductor after the transfer is removed by a cleaning means.

  As the above fixing device, heating and heating are performed while nipping and transporting the recording paper onto which the toner image is transferred at a nip formed by a fixing roller having a built-in halogen lamp and the pressure roller pressed against the fixing roller. There is a heat roller type fixing device that presses, and since the configuration is simple, it has been widely used.

  However, in such a fixing device, since the toner image on the recording paper is pressed against the surface of the fixing roller, the recording paper is not separated while being wound around the fixing roller due to the adhesiveness of the softened toner, and jamming may occur. There is.

  For this reason, a fixing device having a peeling claw as shown in FIG. 5 is known.

  In FIG. 5, the toner image on the recording paper P is heated while being nipped and conveyed at a nip portion N formed by a fixing roller 71 heated by a halogen heater H and a pressure roller 72 pressed against the fixing roller 71.・ Pressure is fixed. Further, a separation claw 101 is provided on the paper discharge side of the recording paper P with respect to the nip portion N, and the leading end thereof is in pressure contact with the surface of the fixing roller 71. Therefore, even if the recording paper P is wound around the fixing roller 71 and discharged, the peeling claw 101 comes into contact with the leading end portion of the recording paper P and is peeled off from the fixing roller 71, so that the above problem is solved.

  However, since the sharp tip of the peeling claw 101 is in pressure contact with the surface of the fixing roller 71, the release layer formed of a fluororesin or the like that covers the surface of the fixing roller 71 is worn due to a relatively short period of use. Or the tip of the peeling claw 101 is worn, and if left as it is, a fixing failure occurs.

In order to solve such a problem, air is jetted to the fixing roller on the recording paper discharge side with respect to the nip portion without using a peeling claw, and the leading end portion of the recording paper wound around the fixing roller is aired. There is known a recording paper peeling device that peels off by the wind pressure (see, for example, Patent Documents 1 and 2).
JP-A-60-247672 US Pat. No. 6,208,827

  In Patent Documents 1 and 2 described above, a plurality of injection ports for injecting air to the fixing roller are provided in parallel with the axial direction of the fixing roller 71. In Patent Document 1, a plurality of ejection openings are provided in two rows so that even if there is a variation in the discharge timing of the recording paper, it can be ejected to the leading edge of the recording paper.

  On the other hand, when fixing the recording paper, wrinkles may occur at both ends in the width direction of the paper. In order to prevent the occurrence of such wrinkles, it is known to form the fixing roller in a drum shape in which the central portion in the axial direction is constricted.

  In order to peel off the recording paper wound around the fixing roller formed in the drum shape as described above, if the ejection port is arranged parallel to the axial direction of the fixing roller 71 as in Patent Documents 1 and 2, the leading edge of the recording paper A portion where air is blown and a portion where air is not blown are generated on the portion, and it is difficult to reliably peel the recording paper from the fixing roller.

  The present invention has been made in view of such a problem, and in a recording paper peeling apparatus that jets air to the leading end of a recording paper that has been fixed and discharged, and peels the recording paper from a fixing member (fixing roller). It is an object of the present invention to propose a recording paper peeling device in which the ejection directions of a plurality of ejection members can be arbitrarily changed corresponding to the shape of the fixing member, and an image forming apparatus including the recording paper peeling device.

  The above object is solved by the following configuration.

  The recording sheet is disposed on the paper discharge side of a nip portion formed by a fixing member heated by a predetermined heating means and a pressure member pressed against the fixing member. In a recording paper peeling apparatus that jets air to the leading end and peels the recording paper from the fixing member, a support member having a circulation hole for circulating the introduced air and a leading end of the recording paper in communication with the circulation hole A plurality of jetting members having jetting holes for jetting air, wherein the plurality of jetting members are supported by the support member and are configured to be independently rotatable. apparatus.

  According to the present invention, even if the fixing member is curved in the axial direction in order to prevent the occurrence of wrinkles on the recording paper, the plurality of ejection members are independently rotated in accordance with the shape of the fixing member to change the ejection direction. Since it can be adjusted, air can be reliably jetted from all the jetting members to the leading edge of the recording paper. Therefore, even if the recording paper is wound around the fixing member due to the soft adhesive property of the toner, the recording paper can be reliably peeled off from the fixing member.

  In addition, the recording paper peeling device may be commonly used for image forming apparatuses having different types of fixing devices. In this case, the degree of curvature of the fixing member may differ depending on the fixing device. Thus, the ejection direction of the ejection member of the recording paper peeling apparatus can be adjusted.

  In addition, even if the fixing member is not curved, even if the central axis of the fixing member and the central axis of the support member that supports the ejection member are inclined and not parallel for some reason, the recording paper is peeled off according to the fixing member. The injection direction of the injection member of the apparatus can be adjusted.

  An embodiment relating to a recording paper peeling apparatus of the present invention will be described in detail with reference to the drawings.

  First, an image forming apparatus having a fixing device using a recording paper peeling device will be described with reference to the basic configuration diagram of FIG.

  In FIG. 1, reference numeral 1 denotes a photosensitive drum which is an electrophotographic photosensitive member. The photosensitive drum 1 is rotationally driven in a direction indicated by an arrow at a predetermined peripheral speed, and a surface of the photosensitive drum 1 is negatively charged by a charger 2. Uniformly charged to VH.

  An exposure device 3 outputs a laser beam modulated in accordance with a time-series digital pixel signal of image information input from an image reading device (not shown), a computer, or the like. The uniformly charged surface of the photosensitive drum 1 is scanned and exposed by this laser beam. As a result, the absolute value of the potential of the exposed portion of the photosensitive drum 1 decreases to become the potential VL, and an electrostatic latent image is formed on the surface of the photosensitive drum 1.

  The developing device 4 includes a developing roller 4a that is rotationally driven. The developing roller 4a is disposed opposite to the photosensitive drum 1, and a thin layer of negatively charged toner is formed on the outer peripheral surface thereof. A developing bias voltage whose absolute value is smaller than the potential VH of the photosensitive drum 1 and larger than the potential VL is applied to the developing roller 4a, whereby the toner on the developing roller 4a becomes the potential of the photosensitive drum 1. Reversal development is performed only on the VL portion, and a toner image is formed.

  On the other hand, the recording paper P, which is a transfer material fed from a paper feed unit (not shown), passes through the registration roller 61 and is synchronized with the photosensitive drum 1 and the charged transfer pole 5 at an appropriate timing synchronized with the rotation of the photosensitive drum 1. To the transfer area formed in The toner image on the photosensitive drum 1 is transferred to the recording paper P by the charged transfer pole 5 to which a transfer bias is applied.

  Reference numeral 62 denotes a fixing guide. The recording paper P onto which the toner image has been transferred is conveyed to the fixing device 7 and the toner image transferred onto the recording paper P is fixed. The recording paper P that has passed through the fixing device 7 and has been fixed with the toner image is discharged onto a paper discharge tray (not shown).

  On the other hand, the photosensitive drum 1 from which the recording paper P has been separated is removed by the cleaning device 8 to remove the transfer residual toner and the like adhering to the surface thereof, and the cleaned photosensitive drum 1 is repeatedly subjected to the next image formation. To be served.

  Although the above-described image forming apparatus is an apparatus that forms a monochrome image, the present invention is also applied to an apparatus that forms a color image.

  Next, the fixing device 7 according to the present invention will be described in detail based on the sectional view of FIG.

  In FIG. 2, the fixing device 7 includes a fixing roller 71 (fixing member) heated by a halogen heater H (heating means), a pressure roller 72 (pressure member) that presses the fixing roller 71 from below, and the like. Yes.

  The fixing roller 71 is formed of a halogen heater H provided in the center, a cored bar 71a formed in a cylindrical shape by aluminum or iron, and a fluororesin such as PFA (perfluoroalkoxy) or PTFE (polytetrafluoroethylene). And a release layer 71b that coats or coats the cored bar 71a with a tube.

  The pressure roller 72 is formed of a core metal 72a formed of a stainless steel or the like, an elastic layer 72b made of a foam of silicon rubber and positioned on the outer peripheral surface of the core metal 72a, a PFA tube, and the like. And a release layer 72c covering the outer peripheral surface of 72b. The pressure roller 72 is urged by an urging member (not shown) and is pressed against the fixing roller 71 from below.

  With the configuration described above, when the fixing roller 71 is rotated clockwise by being driven by a motor (not shown), the pressure roller 72 is rotated counterclockwise. Accordingly, for example, the recording paper P on which the toner image is formed by the image forming apparatus shown in FIG. 1 is sandwiched and conveyed by the nip portion N formed by the fixing roller 71 and the pressure roller 72, and is heated and pressurized. As a result, the toner image on the recording paper P is fixed.

  In some cases, the heating means of the fixing roller 71 may be an induction heating method.

  Here, the toner image on the recording paper P is pressed against the surface of the fixing roller 71, and the recording paper P is prevented from being wrapped around the fixing roller 71 due to the adhesiveness of the softened toner. A recording paper peeling device 9 that ejects air and peels the leading end portion of the recording paper P wound around the fixing roller 71 by the wind pressure of the air is provided on the discharge side of the recording paper P with respect to the nip portion N.

  The recording paper peeling device 9 will be described with reference to FIGS. FIG. 3 is a perspective view of the recording paper peeling device 9, and FIG. 4 is a cross-sectional view of the recording paper peeling device 9.

  The recording paper peeling device 9 shown in both figures is composed of a plurality of injection members 91 for injecting air to the leading end of the recording paper P, a support member 92 for supporting the injection member 91, an electromagnetic valve 93, an air pump 94, and the like. Yes.

  First, a hole 91 a provided in the base portion of the ejection member 91 is fitted into the outer periphery of a pipe-shaped support member 92 disposed in parallel with the axial direction of the fixing roller 71. In this way, the plurality of ejection members 91 are supported by the support member 92 at a predetermined interval.

  The end of the support member 92 is connected to the electromagnetic valve 93 and the air pump 94. When the electromagnetic valve 93 is opened, air is introduced from the air pump 94 to the support member 92. The support member 92 is formed with a circulation hole 92a through which air from the air pump 94 is circulated in the center, and a plurality of communication holes 92b are formed in the side surface. The communication hole 92a and the communication hole 92b communicate with each other. In addition, the ejection member 91 is provided with an ejection hole 91b for ejecting air onto the recording paper P, and the plurality of ejection members 91 are each supporting members 92 so that the communication hole 92b communicates with the ejection hole 91b. Is arranged. Accordingly, the air introduced from the air pump 94 to the support member 92 is ejected from the ejection hole 91b through the flow hole 92a and the communication hole 92b.

  A sensor (not shown) is disposed on the paper discharge side of the nip portion N of the fixing device 7. When the leading end of the recording paper P protrudes from the nip portion N, the sensor detects this and the electromagnetic valve 93. For a short time. As a result, the air ejected from the ejection holes 91b is blown to the leading end portion of the recording paper P, and the recording paper P wound around the fixing roller 71 is peeled off.

  In order to prevent wrinkling of the recording paper P, when the fixing roller 71 is formed in a drum shape (which may be a barrel shape) whose central portion in the axial direction is constricted, the support member 92 Since the plurality of supported ejection members 91 can be independently rotated along the outer periphery of the support member 92, the ejection direction is adjusted by rotating each ejection member 91 according to the shape of the fixing roller 71. As a result, even if the discharged recording paper P adheres to the fixing roller 71 and is curved in the width direction, air can be reliably jetted from all of the ejection members 91 to the leading edge of the recording paper P. Note that after the adjustment is completed, the injection member 91 is fixed to the support member 92 with a set screw 95.

  In addition, since the diameter of the opening 91c on the support member 92 side in the injection hole 91b of the injection member 91 is formed larger than the diameter of the communication hole 92b of the support member 92, the injection member 91 is rotated within a predetermined adjustment range. As long as it is moved, the air injected from the communication hole 92b is not blocked.

  In addition, in the vicinity of the ejection port 91d through which air is ejected from the ejection hole 91b, a peeling portion 91e having a sharp tip is provided, and the leading end of the peeling portion 91e is close to the fixing roller 71. . Accordingly, the recording paper P that is attached to and discharged from the fixing roller 71 with its leading end floating above the fixing roller 71 is mechanically peeled off by the peeling portion 91e. By providing auxiliary means for mechanically peeling like the peeling portion 91e, the air pressure injected from the injection hole 91b can be weakened, and as a result, the air pump 94 can be downsized and the power consumption can be reduced. it can.

  The recording paper peeling device 9 described above is not necessarily applied only to a heat roller type fixing device, and an endless fixing belt is stretched between a heating roller and a fixing roller to fix the fixing belt (fixing member). A belt system that presses and presses a pressure roller (pressing member) to heat and press the recording paper onto which the toner image is transferred at the nip formed between the fixing belt and the pressure roller. It can also be applied to other fixing devices.

1 is a basic configuration diagram of an image forming apparatus. FIG. 3 is a cross-sectional view of a fixing device. It is a perspective view of a recording paper peeling apparatus. It is sectional drawing of a recording paper peeling apparatus. It is a figure of the conventional peeling nail | claw.

Explanation of symbols

DESCRIPTION OF SYMBOLS 7 Fixing device 71 Fixing roller 72 Pressure roller 91 Injection member 91b Injection hole 91c Opening part 91e Separation part 92 Support member 92a Flow hole 92b Communication hole 93 Electromagnetic valve 94 Air pump H Halogen heater P Recording paper

Claims (4)

The recording sheet is disposed on the paper discharge side of a nip portion formed by a fixing member heated by a predetermined heating means and a pressure member pressed against the fixing member. In the recording paper peeling apparatus for ejecting air to the leading end and peeling the recording paper from the fixing member,
A support member having a circulation hole for circulating the introduced air;
A plurality of ejection members having ejection holes that communicate with the flow holes and eject air to the front end of the recording paper;
The recording paper peeling apparatus, wherein the plurality of ejection members are supported by the support member and are configured to be independently rotatable. The support member has a plurality of communication holes for communicating the flow hole and the injection hole, and the diameter of the communication hole is larger than the diameter of the injection hole on the support member side. Item 2. A recording paper peeling apparatus according to Item 1. 3. The peeling part having a tip formed at an acute angle is provided in the vicinity of an ejection port through which air is ejected from the ejection hole, and the peeling part is brought close to the fixing member. The recording paper peeling apparatus as described. An image forming apparatus comprising the recording paper peeling device according to claim 1.

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