JP4532990B2 - Electrophotographic equipment - Google Patents

Description

  The present invention relates to an electrophotographic apparatus such as a printer, a copying machine, and a facsimile machine, and more particularly to a recording medium peeling unit in a fixing device of the electrophotographic apparatus.

  In an electrophotographic apparatus, an electrostatic latent image is formed on a photoreceptor, developed with toner, the developed toner image is transferred to a recording medium such as paper, and is fixed to the recording medium by heat. . In the fixing process, a heating member provided with a heating element is placed at a position in contact with the unfixed image surface of the recording medium on which the unfixed toner image is formed, and from the other surface of the recording medium. In this case, the recording medium is pressed against the heating member by the pressure member, and the toner image is pressure-bonded while being heated and melted to be fixed to the recording medium. In order to obtain high image quality in this fixing process, the heating temperature and pressure of the toner image and the fixing time during which the toner image is subjected to heat and pressure are important factors.

  In addition, as the speed, image quality, and power saving of electrophotographic devices increase, a low heating amount is stably supplied to the toner image, and the heat transfer efficiency from the heating element to the toner image is improved, and then the fixing is performed. The need to secure time is increasing. In Patent Document 1 and Patent Document 2, a heating member or a pressure member is used as a belt-shaped member to reduce the heat capacity of the entire fixing device, improve the heat transfer efficiency from the heating element to the toner image, a recording medium and a heating member, It is described that the contact distance with the pressure member is increased.

JP-A-10-161464 (Description of paragraphs (0014) to (0017)) JP 2001-117397 A (Description of paragraphs (0013) to (0015))

  However, in the fixing device having the configuration described in Patent Document 1 or Patent Document 2, since the melt-compressed toner image becomes a hot-melt adhesive between the heating member and the recording medium, the toner image adheres closely to the heating member side. There is a problem that causes jamming of the recording medium. As described in Patent Document 1, in the system in which a heating member is used as a roller and a part of a belt as a pressure member is wound, the recording medium is curled toward the heating member, so that the recording medium is easily adhered to the fixing device. The rate of jam occurrence increases.

  Therefore, a method in which a peeling claw or a thin guide plate is provided on the heating member to forcibly peel the recording medium from the heating member is used, but when the peeling claw is used, the recording medium is peeled off. Since the peeling claw comes into contact with the image and rubs, the image quality deteriorates. In addition, when a thin plate-shaped guide plate is used, the contact area between the recording medium and the guide plate is increased, so that the conveyance resistance of the recording medium is increased, which only causes deformation of the recording medium and clogging of the recording medium. In addition, there is a problem that the molten toner adheres and accumulates on the guide plate and the adhered molten toner comes into contact with the recording medium to cause clogging of the recording medium.

  Also known is a method of adding ribs to the guide plate to reduce the contact area with the recording medium, reduce the conveyance resistance of the recording medium, and minimize adhesion of molten toner to the guide plate. Is in contact with the toner image on the recording medium, and when the recording medium passes over the heated and heated guide plate, the rib contacting the toner image rubs while reheating the toner image, and the image surface is glossy. There is a problem of degrading the image quality, such as generating vertical streaks or scraping the toner image to cause vertical flaws on the image.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a fixing device capable of eliminating such drawbacks of the prior art and maintaining high image quality and high reliability with a simple configuration, and a full-color electrophotographic apparatus using the same. .

  In order to achieve the above object, the full-color electrophotographic apparatus of the present invention comprises a recording medium peeling means for forcibly peeling a recording medium on which a toner image is fixed by thermocompression bonding from a rotating heating member. Ribs are provided so as to be inclined in the recording medium width direction with respect to the conveyance direction of the recording medium.

  In the full-color electrophotographic apparatus of the present invention, the recording medium peeling means is made of a thin steel plate, and is fixed to a support member having an appropriate strength to ensure the rigidity of the recording medium.

  The full-color electrophotographic apparatus of the present invention has a rib installed on the support member so as to be inclined in a recording medium direction with respect to a recording medium conveyance direction, and a hole is provided at a corresponding position of the recording medium peeling means. The rib was protruded from the hole.

  In the full-color electrophotographic apparatus of the present invention, the recording medium peeling means has a thin plate shape, and has a plurality of ribs formed to be inclined in the recording medium width direction with respect to the recording medium conveyance direction, Rib ends are joined.

  In the full-color electrophotographic apparatus of the present invention, the rib has an inclination of 10 ° to 50 ° in the recording medium width direction with respect to the conveyance direction of the recording medium.

  In the full-color electrophotographic apparatus of the present invention, the fixing device is in contact with a heating member that contacts a toner image formed on the recording medium and a surface opposite to the toner image surface of the recording medium. Has a pressure member that forms a nip sandwiched between the heating member and the recording medium peeling means has a thin plate shape, and the tip of the recording medium peeling means is 4 from the recording medium discharge portion of the nip. Holds a distance of -10 mm.

  In the full-color electrophotographic apparatus of the present invention, the fixing device is in contact with a heating member that contacts a toner image formed on the recording medium and a surface opposite to the toner image surface of the recording medium. Has a pressure member that forms a nip sandwiched between the recording medium and the heating member, the recording medium peeling means has a thin plate shape, and the recording medium peeling means is arranged in the direction of discharging the recording medium from the nip. On the other hand, it is installed at an angle of 5 ° to 30 ° away from the heating member.

  In the full-color electrophotographic apparatus of the present invention, the front and back surfaces of the recording medium peeling means are coated with a fluororesin.

  According to the present invention, the recording medium peeling means for forcibly peeling the recording medium on which the toner image is fixed by thermocompression bonding from the rotating heating member is provided, and the recording medium peeling means is in the recording medium width direction with respect to the recording medium transport direction. Desirably, the ribs installed at an angle of 10 ° to 50 ° can disperse the position in contact with the toner image, thereby generating glossy vertical stripes on the image surface, or causing the image to have vertical stripes on the stripes. Deformation of the recording medium and clogging of the recording medium can be prevented while eliminating image quality deterioration such as generation of scratches.

  Further, by forming the recording medium peeling means fixed to a support member having an appropriate strength to ensure its rigidity, the reliability can be improved without deforming the recording medium peeling means. Furthermore, if the rib is provided in the support member, a hole is provided at a corresponding position of the recording medium peeling means, and the rib is protruded, it becomes easy to provide a recording medium peeling means with high accuracy.

  Further, when the adjacent ends of the ribs are joined together, or the front and back surfaces of the recording medium peeling means are coated with a fluorine resin, or a fluorine-based heat-resistant tape is attached, the adhesion between the recording medium and the recording medium peeling guide is further improved. Image defects due to rubbing with the toner image and clogging of the recording medium can be prevented more reliably.

  The details of the present invention will be described below with reference to the drawings.

  FIG. 1 is a perspective view of the periphery of the recording medium peeling means of the fixing device of this embodiment, FIG. 2 is a schematic configuration diagram of a full-color electrophotographic apparatus including the fixing device, and FIG. 3 is a schematic configuration diagram of the fixing device of this embodiment. It is.

  First, a schematic configuration and operation of a full-color electrophotographic apparatus will be described with reference to FIG. A drum-like or belt-like (drum-like in this embodiment) intermediate transfer device 11 is disposed in the substantially central portion of the full-color electrophotographic apparatus, and a photosensitive device 12, a transfer device 13, a separation device 14, and an intermediate transfer are provided around the intermediate transfer device 11. A device cleaning means 15 is provided.

  In addition, a charger 16, a photosensitive member cleaning unit 17, an afterimage removing unit 18, and the like are disposed around the belt-shaped or drum-shaped (belt-shaped in this embodiment) photosensitive device 12. Developers 19K (black), 19Y (yellow), 19M (magenta), and 19C (cyan) in which toners that are finely colored powders of four different colors are encapsulated are arranged in an overlapping manner, and an exposure unit 20 is disposed below the developing devices. Further, a recording medium holding unit 21 and a recording medium supply device 22 on which a sheet-like recording medium 8 such as paper or OHP is stacked are arranged below the recording medium. A fixing device 10 and a recording medium discharge device 23 are arranged on the upper part of the electrophotographic apparatus.

  In this configuration, the charger 16 uniformly charges the surface of the photosensitive device 12. Next, exposure is performed in dot units by the exposure unit 20 based on printing information such as images and characters from a personal computer or an image scanner, and an electrostatic latent image is formed on the surface of the photosensitive device 12.

  Thereafter, the electrostatic latent image is visualized as a toner image by being supplied with toner by any of the developing devices 19K, 19Y, 19M, and 19C, and developed, and the photosensitive device 12 and the intermediate transfer device 11 are in contact with each other. It is conveyed to one transfer position T1. At the first transfer position T1, the toner image is transferred to the surface of the intermediate transfer device 11 due to a potential difference between the photosensitive device 12 and the intermediate transfer device 11 supplied from a power source (not shown).

  After passing through the first transfer position T1, the surface of the photosensitive device 12 is irradiated with light by the afterimage removing means 18 to drop the potential below a certain level, and the electrostatic latent image is erased. Residual toner remaining on the surface that has not been transferred at T1 is cleaned and prepared for the formation of the next toner image.

  By repeating the above process for each color as many times as necessary, a toner image of each color suitable for image and character information is formed on the surface of the intermediate transfer device 11 in an overlapping manner. Thereafter, the toner image is collectively transferred to the recording medium 8 supplied from the recording medium holding means 21 by the recording medium supply device 22 by the transfer device 13 at the second transfer position T2. The recording medium 8 to which the toner image has been transferred is peeled off from the intermediate transfer device 11 by the separation device 14, transported to the fixing device 10, fixes the toner image to the recording medium 9, and is discharged by the recording medium discharge device 23.

  As shown in FIG. 3, the fixing device 10 includes a heating roller 1, a pressure belt 2, a nip pressure member 3, a heating source 4, a recording medium peeling guide 5, and a thermistor 6 as temperature detecting means. The heating roller 1 is provided with a release layer such as tetrafluoroethylene perfluoroalkyl vinyl ether copolymer (PFA) or fluororesin on a hollow core metal such as aluminum, or between the core metal and the release layer. A heat-resistant elastic layer such as silicone rubber is provided on the core, or only a heat-resistant elastic layer is provided on the metal core, and a heating source 4 such as a heater lamp is provided therein, and the heat of the heating source 4 passes through the heating roller 1 to form a toner image. 7 and the recording medium 8.

  The pressure belt 2 is, for example, an endless nickel belt formed by electroforming having a thickness of 30 to 50 μm or an endless belt made of polyimide resin having a thickness of 40 to 100 μm. In addition, a silicone rubber layer having a thickness of 20 to 300 μm is provided on the outer peripheral surface of these endless belts, or the outer peripheral surface is subjected to release treatment with PFA or fluororesin.

  The pressure belt 2 is stretched around the nip pressure member 3 in a tensionless or stretched state, and the heating roller 1 is pressure-bonded to the nip pressure member 3 with the pressure belt 2 interposed therebetween. The nip pressurizing member 3 is configured by providing a heat resistant elastic layer such as silicone rubber on the surface of a metal pad such as aluminum or a heat resistant resin such as metal or PPS (polyphenylene sulfide). Further, the nip pressurizing member 3 may be made of a metal such as aluminum or a freely rotatable roller shape in which a heat-resistant elastic layer such as silicone rubber is provided on the surface of the metal. The heating roller 1 is rotationally driven in the P direction by a driving source (not shown), and the pressure belt 2 is driven in the Q direction by the rotation of the heating roller 1. As a result of these rotations, the recording medium 8 on which the unfixed toner image 7 is placed is in a direction in which the toner image surface is in contact with the heating roller 1, and the pressure belt 2 is at a distance where the pressure belt 2 is pressed against the heating roller 1. It is configured to pass with. The thermistor 6 is installed on the outer peripheral surface of the heating roller 1, and the temperature of the surface of the heating roller 1 is controlled by adjusting the energization amount to the heating source 4.

  The recording medium peeling guide 5 is disposed at a position where the recording medium 8 exiting from the fixing outlet portion O is forcibly peeled from the heating roller 1, and the leading end of the guide is in the vicinity of the fixing outlet portion O and on the outer peripheral surface of the heating roller 1. It is close.

  Further, the recording medium peeling guide 5 is formed of a thin steel plate or a heat-resistant resin molded product, and as shown in FIG. 1, ribs 9 are disposed on the passage surface of the recording medium 8 so as to be inclined with respect to the conveyance direction of the recording medium. It has.

  Next, the operation of the fixing device 10 will be described with reference to FIGS. The recording medium 8 onto which the unfixed toner image 7 formed by each process of electrophotography is transferred is sandwiched between the nip portion of the heating roller 1 and the pressure belt 2 with the surface of the toner image 7 in contact with the heating roller 1. Then transported. After that, the recording medium 8 moves while being heated and pressurized with the rotation of the heating roller 1 while being in close contact with the heating roller 1, and while passing through the heating roller 1, the toner image 7 is melted and pressed on the recording medium 8 and fixed. Ends.

  When the recording medium 8 is ejected from the recording medium outlet O, the melted and pressed toner image becomes an adhesive between the heating roller 1 and the recording medium 8, and therefore the recording medium 8 is not peeled off from the heating roller 1. Will occur. The recording medium 8 that is in close contact with the heating roller 1 is forcibly separated by the recording medium peeling guide 5. The recording medium 8 that has been forcibly peeled is discharged while being in contact with the recording medium peeling guide 5. However, since the ribs are provided on the recording medium 8 passing surface of the recording medium peeling guide 5, the toner image 7 The contact area with the surface can be reduced, thereby reducing the conveyance resistance of the recording medium 8, deformation of the recording medium 8 due to the conveyance resistance, clogging of the recording medium, or molten toner adhering to the recording medium peeling guide 5, It is possible to prevent the recording medium from being clogged due to the adhered and melted toner coming into contact with the recording medium 8.

  Furthermore, by arranging the rib 9 to be inclined with respect to the conveyance direction of the recording medium 8, contact with the rib 9 at a specific point in the width direction of the recording medium 8 can be avoided, so that the temperature is increased by heating. When the recording medium passes over the recording medium peeling guide 5, the ribs that come into contact with the toner image are rubbed while reheating the toner image, thereby preventing glossy vertical stripes on the image surface and vertical stripes on the stripes. Can do.

  Further, in order to forcefully peel the recording medium 8, it is desirable that the tip of the recording medium peeling guide 5 be as close as possible to the heating roller 1. Considering accuracy and straightness of the tip of the recording medium peeling guide 5, the recording medium peeling guide 5 is advantageously made of a thin steel plate. In this case, when the rib 9 is formed by squeezing and extruding a predetermined position of the steel plate, a recording medium peeling guide that can easily obtain a desired effect can be formed.

  Alternatively, as shown in FIG. 4, the recording medium 8 passage surface that is not brought into contact with the recording medium 8 of the recording medium peeling guide 5 made of a thin steel plate is moved away from the recording medium 8 by the diaphragm 9b, and the remaining portion is in contact with the recording medium 8. By doing so, the same effect can be obtained, and it becomes easy to ensure the plane accuracy of the recording medium 8 passage surface and the tip accuracy of the recording medium peeling guide 5.

  Further, as shown in FIGS. 1 and 4, the recording medium peeling guide 5 is fixed to a supporting member 5b having an appropriate rigidity, such as a steel plate having a thickness of 0.8 mm or more, for example, when a paper jam occurs. Since the support member 5b can receive the force from the recording medium 8 to be performed, it is possible to prevent the recording medium peeling guide 5 made of a thin steel plate from being deformed by a sudden strong load.

Further, as shown in FIG. 5, the rib 9 is disposed on the support member 5b so as to be inclined with respect to the conveyance direction of the recording medium 8, and a hole is formed at the position of the recording medium peeling guide 5 corresponding to the position of the rib 9 of the support member 5b. If the rib 9 is provided so as to protrude from the recording medium peeling guide 5, it is possible to eliminate a large deformation process such as a drawing process at the time of manufacturing the paper peeling guide 5. Therefore, it is easy to ensure the leading edge accuracy of the paper peeling guide 5. Become.

  In addition, as shown in FIG. 6, the ribs 9 arranged so as to be inclined with respect to the respective recording medium conveyance directions described above are combined with the ends of the adjacent ribs so that the entire width of the recording medium 8 is obtained. The contact time between the recording medium 8 and the rib 9 can be made equal, and image defects due to rubbing with the toner image 7 can be prevented more reliably.

  Further, if the inclination of the rib 9 installed on the recording medium peeling guide 5 described so far is too small, the rib 9 is likely to rub against a specific position of the recording medium 8, and image defects due to rubbing with the toner image 7 are caused. If the inclination is too large and the inclination is too large, the contact area with the recording medium 8 increases, and the conveyance resistance of the recording medium 8 increases, which causes deformation of the recording medium 8 and clogging of the recording medium 8. Therefore, it is desirable to set the inclination θ of the rib 9 to 10 ° to 50 °.

  Further, if the recording medium peeling guide 5 described so far is coated with a fluororesin on the front and back surfaces or a fluororesin-based heat-resistant tape is attached, the friction resistance between the recording medium 8 and the recording medium peeling guide 5 is reduced. In addition, since toner adhesion to the front and back surfaces of the recording medium peeling guide can be prevented, adhesion between the recording medium 8 and the recording medium peeling guide 5 can be prevented, and image defects or recording media due to rubbing with the toner image 7 can be prevented. 8 can be more reliably prevented.

It is a sheet peeling mechanism periphery view of the fixing device of the embodiment. 1 is an overall view of an electrophotographic apparatus according to an embodiment. 1 is a cross-sectional view of a fixing device according to an embodiment. It is a sheet peeling mechanism periphery view of the embodiment. It is a sheet peeling mechanism periphery view of the embodiment. It is a sheet peeling mechanism periphery view of the embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Heat roller, 2 ... Pressure belt, 3 ... Nip pressure member, 4 ... Heat source, 5 ... Recording medium peeling guide, 5b ... Support member, 6 ... Thermistor, 7 ... Toner image, 8 ... Recording medium, 9 , Rib, 9b, aperture, 9c, hole, 10, fixing device, 11 ... intermediate transfer device, 12 ... photosensitive device, 13 ... transfer device, 14 ... separation device, 15 ... intermediate transfer device cleaning means, 16 ... charger, DESCRIPTION OF SYMBOLS 17 ... Photoconductor cleaning means, 18 ... Afterimage removal means, 19K, 19Y, 19M, 19C ... Developing device, 20 ... Exposure means, 21 ... Recording medium holding means, 22 ... Recording medium supply device, 23 ... Recording medium discharge device, P: heating roller rotation direction, Q: pressure belt running direction, T1: first transfer position, T2: second transfer position, θ: paper peeling guide rib tilt angle.

Claims (3)

A photosensitive device; an exposure unit that forms an electrostatic latent image on the photosensitive device; a plurality of developing units that expose the electrostatic latent image with toners of black, yellow, magenta, and cyan; A transfer device that forms a full-color toner image on a recording medium by superimposing toner images that have been manifested with toner; a recording medium supply device that transports the recording medium to the transfer device; and the full-color toner image on the recording medium. In a full-color electrophotographic apparatus having a fixing device for fixing,
The fixing device includes a recording medium peeling means made of a steel plate for forcibly peeling the recording medium on which the toner image is fixed by thermocompression bonding from a heating member that rotates, and a support member .
The support member has a rib installed on the recording medium side on which the toner image is formed and inclined with respect to the recording medium conveyance direction in the recording medium width direction, and the tip of the recording medium peeling means is the heating member A full color, wherein the recording medium peeling means is fixed to the support member so as to be close to the support member, and a hole is provided at the position of the recording medium peeling means corresponding to the position of the rib of the support member , and the rib protrudes from the hole. Electrophotographic device. In a full-color electrophotographic apparatus according to claim 1, wherein the ribs are more disposed to be inclined to the recording medium width direction with respect to the conveying direction of the recording medium, the ends of each side by side Ru said rib is coupled A full-color electrophotographic apparatus characterized by 2. The full color electrophotographic apparatus according to claim 1, wherein the rib has an inclination of 10 [deg.] To 50 [deg.] In the recording medium width direction with respect to the conveyance direction of the recording medium.

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