JP2016090839A - Fixing device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device that can contact/separate from a pressure member, deal with a variation of the position of the surface of the pressure member, and separate a recording material wound around the pressure member while suppressing an adverse effect on the pressure member, and an image forming apparatus.SOLUTION: A fixing device includes: a fixing member; a pressure member that forms a fixing nip part with the fixing member; heating means for heating the fixing member; a pressure-application and separation member that can contact/separate from the pressure member with a contact/separation mechanism; a separation pawl that can deal with a variation of the position of the surface of the pressure member with a dealing mechanism and attached to the pressure-application and separation member, and causes a recording material carrying an unfixed image to pass through the fixing nip part to fix the image. When performing double-sided paper feed of the recording material, the fixing device brings the pressure-application and separation member into contact with the pressure member and separates a recording material wound around the pressure member from the pressure member with the separation pawl.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a fixing device and an image forming apparatus including the fixing device.

  A fixing device used in an electrophotographic image forming apparatus performs fixing by melting and penetrating a toner image carried on a recording material by applying heat and pressure.

  In recent years, the market demands shortening of the time (warm-up time) required from a normal temperature state to a predetermined printable temperature, such as when power is turned on. There is also a demand for shortening the time (first print time) from when a print request is received to when a print operation is performed through a print preparation and paper discharge is completed.

  In response to these requirements, for example, Patent Document 1 discloses that in an arrangement using an endless belt, it is possible to warm the entire belt, shorten the first print time from the heating standby time, and reduce the amount of heat during high-speed rotation. A fixing device that can be solved is disclosed.

  The fixing device of Patent Document 1 has a configuration in which the endless belt is indirectly heated through the metal heat conductor, but a configuration in which the endless belt is directly heated (without the metal heat conductor) is also considered. . As a result, the first print time can be further shortened, and the cost can be reduced without using a metal heat conductor.

  An object of the present invention is to separate the recording material wound around the pressure member while being able to contact and separate from the pressure member, to cope with fluctuations in the surface position of the pressure member, and suppressing adverse effects on the pressure member. An object of the present invention is to provide a fixing device and an image forming apparatus that can be used.

  The object is to contact and separate the pressure member by a fixing member, a pressure member that forms a fixing nip portion between the fixing member, a heating unit that heats the fixing member, and a contact / separation mechanism. And a separation claw attached to the pressure separation member capable of following a change in the surface position of the pressure member by a copying mechanism, and carrying an unfixed image In a fixing device for fixing a recording material through the fixing nip portion, when performing double-sided recording material recording, the pressure separation member is brought into contact with the pressure member and wound around the pressure member. This is solved by a fixing device that separates the attached recording material from the pressure member by the separation claw.

  According to the fixing device of the present invention, the pressure separation member can be brought into contact with the pressure member when necessary (during both-side paper passing) and separated when not necessary by the contact / separation mechanism. The recording material wound around the pressure member can be separated while suppressing adverse effects such as sliding.

  Further, a separation claw is attached to the tip of the pressure separation member, and the separation claw can follow the change in the surface position of the pressure roller 131 by a copying mechanism. As a result, even when the outer diameter of the pressure roller 131 expands due to heat during sheet passing or contracts due to aging, the recording material can be appropriately separated.

1 is a schematic diagram illustrating a cross section of a color printer that is an embodiment of an image forming apparatus. 1 is a schematic diagram according to an embodiment of a fixing device installed in an image forming apparatus. It is a schematic diagram which shows the pressurization separation member and contact / separation mechanism which concern on 1st Embodiment. It is a schematic diagram which expands and shows the front-end | tip part of a pressure separation member. It is a schematic diagram which shows the separation nail | claw and copying mechanism which concern on 1st Embodiment. It is a schematic diagram which shows the front-end | tip part of the separation nail | claw which concerns on 2nd Embodiment. It is a schematic diagram which expands and shows the front-end | tip part of a pressure separation member. It is a modification of 2nd Embodiment and is a schematic diagram which shows the front-end | tip part of a separation nail. (A) is a schematic diagram which shows the front-end | tip part of the separation nail | claw which concerns on 3rd Embodiment, (b) is a schematic diagram which shows the separation claw seen from the arrow A. FIG. 6 is a schematic diagram according to another embodiment of a fixing device mounted on the image forming apparatus.

  Hereinafter, before describing the embodiment, a preliminary matter for facilitating understanding of the embodiment will be described.

  In recent years, the frequency of use of recycled paper, thin paper, backing paper and the like as recording materials has increased. When such a recording material is fixed by a fixing device, there arises a problem that the recording material is wound around a pressure roller as a pressure member. This is particularly noticeable when printing on both sides. By adjusting the leading edge margin of the recording material to be conveyed, the winding of the recording material can be alleviated to some extent, but there is a high possibility that it will not be adjusted as intended in the market.

  In order to prevent the recording material from being wound around the pressure roller, a pressure separating member for separating the recording material from the pressure roller may be provided. If the pressure separating member is brought into contact with the pressure roller or approached as much as possible, the recording material wound around the pressure roller can be separated.

  However, if the pressure separating member is brought into contact with the pressure roller, a sliding mark may be generated on the pressure roller, and a streak mark may be generated on the image of the recording material. Further, the position of the pressure roller varies due to the pressure depressurization operation. Furthermore, the outer diameter expands due to the heat at the time of passing the paper, or shrinks with age. That is, there is a problem that the positional relationship between the pressure separating member and the pressure roller surface varies.

  Therefore, in order to suppress the occurrence of sliding marks on the pressure roller, it is desirable that the pressure separation member is brought into contact with the pressure roller when necessary and separated when not necessary. Further, it is desirable that the pressure separation member follows or follows the change in the surface position such as the movement of the pressure roller and the change in the outer diameter.

  In the following embodiments, the recording material wound around the pressure member can be separated while being able to contact and separate from the pressure member, can cope with fluctuations in the surface position of the pressure member, and suppresses adverse effects on the pressure member. A fixing device and an image forming apparatus that can be used will be described.

(First embodiment)
FIG. 1 is a schematic diagram illustrating a cross section of a color printer that is an embodiment of an image forming apparatus. The color printer is a tandem system in which image forming units for forming a plurality of color images are juxtaposed along the belt extending direction, but the present invention is not limited to this system. It is also possible to target not only printers but also copying machines and facsimile machines.

  As shown in FIG. 1, photoconductors 20 </ b> Y, 20 </ b> C, 20 </ b> M, and 20 </ b> Bk that are image carriers are arranged in parallel at the center of the image forming apparatus 1. Each of the photoconductors 20Y, 20C, 20M, and 20Bk can form images corresponding to yellow (Y), cyan (C), magenta (M), and black (Bk), respectively. Since these image forming units have the same configuration except for the difference in developer (toner) color, in the following description, the subscripts Y, C, M, and Bk in the reference numerals will be omitted as appropriate.

  Around each photoreceptor 20, a charging member 30, a developing device 40, and a cleaning unit 50 are provided. The photosensitive member 20 is driven to rotate clockwise, and a charging member 30 is pressed against the surface of the photosensitive member 20, and the charging member 30 is driven to rotate as the photosensitive member 20 is driven to rotate. In addition, a predetermined bias voltage is applied to the charging member 30 by a high voltage power source (not shown), and the surface of the photoconductor 20 to be rotationally driven can be uniformly charged. The photosensitive member 20, the charging member 30, the developing device 40, and the cleaning unit 50 are detachably installed from the image forming apparatus 1, respectively.

  Further, an exposure device 8 is provided in parallel below these four photoreceptors 20 in parallel. The exposure apparatus 8 includes constituent members such as a light source, a polygon mirror, an f-θ lens, and a reflection mirror. The exposure device 8 exposes each photoconductor 20 charged by the charging member 30 based on image information formed according to image data of each color toner, and forms an electrostatic latent image on each photoconductor 20. produce. The electrostatic latent image formed on the photoconductor 20 using the exposure device 8 is developed and visualized by applying each color toner when passing through the developing device 40 by the rotation of the photoconductor 20. .

  Note that toner bottles 9Y, 9C, 9M, and 9Bk filled with toners of yellow, cyan, magenta, and black are disposed above the inside of the image forming apparatus 1. A predetermined replenishment amount of toner is replenished from the toner bottles 9Y, 9C, 9M, and 9Bk to the color developing devices 40Y, 40C, 40M, and 40Bk through a conveyance path (not shown).

  Further, an endless belt-like intermediate transfer belt 11 configured as an intermediate transfer member is disposed opposite to the photosensitive member 20 of each image forming unit, and each photosensitive member 20 contacts the surface of the intermediate transfer belt 11. ing. The intermediate transfer belt 11 is configured by being wound around a plurality of support rollers (for example, support rollers 72 and 73). In the illustrated example, the support roller 73 is connected to a drive motor as a drive source (not shown), and the intermediate transfer belt 11 is rotated counterclockwise in the figure by the drive of the drive motor. The rotatable support roller 73 also rotates. A primary transfer roller 12 is disposed inside the intermediate transfer belt 11 so as to be opposed to the photoconductor 20 with the belt interposed therebetween. A primary transfer bias is applied to the primary transfer roller 12 from a high voltage power source (not shown), and the toner image visualized by the developing device 40 is primarily transferred to the intermediate transfer belt 11.

  The primary transfer residual toner that is not primarily transferred and remains on the photoconductor 20 is removed by the cleaning unit 50 in preparation for the next image forming operation by the photoconductor 20, and the toner on the photoconductor 20 is completely removed. Removed.

  Further, a secondary transfer roller 5 as a secondary transfer device is provided on the downstream side in the driving direction of the intermediate transfer belt 11. The secondary transfer roller 5 faces the support roller 72 with the intermediate transfer belt 11 interposed therebetween, and the secondary transfer roller 5 and the support roller 72 form a secondary transfer nip portion via the intermediate transfer belt 11. ing. The image forming apparatus 1 further includes a registration roller pair 4 in addition to a sheet feeding device 61 and a feeding roller 3 as a stacking unit for sheets S as recording materials. Further, a fixing device 100 and a paper discharge roller pair 7 are provided on the downstream side in the transport direction of the paper S when viewed from the secondary transfer roller 5.

  Subsequently, an image forming operation will be described. First, the photoconductor 20 is rotated clockwise by a drive source (not shown). At this time, the surface of the photoconductor 20 is irradiated with light from a static eliminator (not shown) to initialize the surface potential. Next, the surface of the photoconductor 20 is uniformly charged to a predetermined polarity by the charging member 30. Next, the surface of the photoconductor 20 is irradiated with laser light from the exposure device 8, thereby forming an electrostatic latent image on the surface of the photoconductor 20. The image information exposed on each photoconductor 20 at this time is single-color image information obtained by separating a desired full-color image into yellow, cyan, magenta, and black toner color information. The electrostatic latent image formed on the photoreceptor 20 is visualized as a visualized toner image by being supplied with each color toner (developer) from the developing device 40 when passing through the developing device 40.

  The intermediate transfer belt 11 is driven to run counterclockwise in the figure, while a primary transfer voltage having a polarity opposite to the toner charging polarity of the toner image formed on the photoconductor 20 is applied to the primary transfer roller 12. Is done. As a result, a transfer electric field is formed between the photoconductor 20 and the intermediate transfer belt 11, and the toner image on the photoconductor 20 is electrostatically transferred onto the intermediate transfer belt 11 that is driven to rotate in synchronization with the photoconductor 20. Primary transfer. In this way, the respective color toner images that are primarily transferred are superimposed on the intermediate transfer belt 11 at successive timings from the upstream side in the transport direction of the intermediate transfer belt 11 to form a desired full-color image.

  On the other hand, the sheets S on which an image is formed are separated and fed one by one from a bundle of sheets stacked on the sheet feeding device 61 to the registration roller pair 4 by a conveying member such as a feeding roller 3. At that time, the leading edge of the conveyed paper S hits the nip portion of the registration roller pair 4 which has not started to rotate, forms a loop, and registration of the paper S is performed. After that, at the timing of the full color toner image carried on the intermediate transfer belt 11, the rotational driving of the registration roller pair 4 is started, and the secondary transfer nip portion constituted by the support roller 72 and the secondary transfer roller 5. The sheet S is sent out toward.

  In the present embodiment, a transfer voltage having a polarity opposite to the toner charging polarity of the toner image on the surface of the intermediate transfer belt 11 is applied to the secondary transfer roller 5, whereby the full color toner image formed on the surface of the intermediate transfer belt 11 is transferred to the sheet S. It is transcribed at the same time. Next, the sheet S to which the toner image has been transferred is conveyed to the fixing device 100, and heat and pressure are applied when passing through the fixing device 100, and the toner image is fixed on the sheet S as a permanent image. Then, the sheet S is discharged to a sheet discharge section such as a discharge tray via the pair of discharge rollers 7, and the image forming operation is completed. The residual toner remaining on the intermediate transfer belt 11 without being transferred at the secondary transfer nip is removed and collected by the intermediate transfer belt cleaning means 13.

  The above description is an image forming operation when a full-color image is formed on the paper S. A single-color image is formed using any one of the photoconductors 20, or a two-color or three-color image is formed. It can also be formed. When monochrome printing is performed using the printer of this embodiment, an electrostatic latent image is formed only on the photoreceptor 20Bk, developed by the same means, transferred to the paper S, and fixed by the fixing device 100. That's fine.

  FIG. 2 is a schematic diagram according to an embodiment of a fixing device mounted on the image forming apparatus. As shown in FIG. 2, the fixing device 100 includes a fixing belt 121 as a fixing member that rotates in contact with an unfixed image, and a pressure member that forms a fixing nip N between the fixing belt 121. A pressure roller 131. Further, the fixing device 100 includes halogen heaters 125 a, 125 b, and 125 c that are heating units, a fixing separation member 126 that separates the paper S from the fixing belt 121, and a pressure separation member 200 that separates the paper S from the pressure roller 131. Etc.

  The fixing belt 121 is formed of an endless belt member that is thin and flexible. As the belt member, for example, a metal belt such as nickel or SUS or a resin material such as polyimide can be used. In the fixing belt 121, three halogen heaters 125a, 125b, and 125c and a reflection member 122 that reflects heat from the halogen heaters 125a, 125b, and 125c to the fixing belt 121 are provided. The fixing belt 121 is directly heated by radiant heat from the inner peripheral side by the halogen heaters 125a, 125b, 125c and the reflection member 122.

  Further, a nip forming member 123 that forms a fixing nip portion N by contacting the pressure roller 131 from the inner peripheral side of the fixing belt 121 and a stay 124 as a support member that supports the nip forming member 123 are provided. . The halogen heaters 125a, 125b, and 125c are fixed to the side plates (not shown) of the fixing device 100 at both ends.

  The pressure roller 131 is a rotatable roller member, and includes a core thread 132, an elastic layer 133 formed of solid rubber or foamed sponge, and a surface layer 134 for improving toner releasability. Is done. The pressure roller 131 is rotationally driven by a drive source such as a motor (not shown). The pressure roller 131 is pressed against the fixing belt 121 by a spring or the like, and has a predetermined nip width by the elastic layer 133 being crushed and deformed.

  The fixing separation member 126 is disposed downstream of the fixing nip portion N in the transport direction of the paper S. The fixing / separating member 126 is a flat plate member made of metal such as SUS, and can be separated without damaging the surface of the paper S. Similarly, the pressure separating member 200 is also arranged downstream of the fixing nip portion N in the transport direction of the paper S, and separates the paper S from the pressure roller 131. The pressure separating member 200 is a characteristic part of the present invention.

  Hereinafter, characteristic portions of the present invention will be described.

  FIG. 3 is a schematic diagram illustrating a pressure separation member and a contact / separation mechanism according to the first embodiment. As shown in FIG. 3, a support column 203 is disposed on a support plate 202 inside the fixing device 100. A rotary shaft 204 is attached to the support column 203, and a pressure separating member 200 and a lever 205 are attached to the rotary shaft 204 in opposite directions. A pressure roller 131 is rotatably disposed below the distal end portion of the pressure separation member 200. In addition, a spring 206 is connected between the vicinity of the center of the pressure separating member 200 and the support plate 202, and a force for bringing the pressure separating member 200 into contact with the pressure roller 131 acts.

  A solenoid 208 that performs a pulling operation when energized is disposed beside the column 203. A movable part that performs the pull operation of the solenoid 208 is attached to the tip of the lever 205. The energization of the solenoid 208 is controlled by a control unit (not shown) in the fixing device 100.

  In the pressure separating member 200 and the contact / separation mechanism 210 configured as described above, when the solenoid 208 is energized, the solenoid 208 performs a pulling operation, and the lever 205 is lowered. Therefore, the pressure separating member 200 is separated from the pressure roller 131 via the rotating shaft 204. On the other hand, when the solenoid 208 is deenergized, the lever 205 returns to the original position, and the pressure separating member 200 contacts the pressure roller 131.

  FIG. 4 is an enlarged schematic view showing the tip portion of the pressure separating member. As shown in FIG. 4, the pressure separation member 200 includes two abutting members 211 that contact the pressure roller 131 and a plurality of separation claws 201 that separate the recording material. The abutting member 211 is in contact with the pressure roller 131 outside the sheet passing range region of the pressure roller 131. The plurality of separation claws 201 are attached in a line in the longitudinal direction at the tip of the pressure separation member 200.

  It is desirable that the pressure separating member 200 follow the surface of the pressure roller 131. Therefore, the pressure separating member 200 abuts on the pressure roller 131 with the abutting member 211. Since the abutting member 211 is provided outside the paper passing range area of the pressure roller 131, the influence on the passed paper image can be reduced.

  FIG. 5 is a schematic diagram illustrating the separation claw and the copying mechanism according to the first embodiment. As shown in FIG. 5, a support column 213 is disposed at the distal end portion of the pressure separation member 200. A wedge-shaped separation claw 201 is attached to the support column 213 so as to be rotatable about a wedge-shaped thick portion as a rotation center. Further, the tip of the separation claw 201 is arranged so that a clearance is generated on the surface of the pressure roller 131. Further, a spring 214 is connected between the separation claw 201 and the pressure separation member 200, and a force is applied to make the tip of the separation claw 201 face the surface of the pressure roller 131.

  In the separation claw 201 and the copying mechanism 212 configured as described above, when the surface of the pressure roller 131 comes into contact with the separation claw 201, the tip of the separation claw 201 moves following the surface position of the pressure roller 131.

  Next, an operation for separating the recording material wound around the pressure roller 131 will be described.

  When the two-sided sheet feeding is started, the control unit deenergizes the solenoid 208. In that case, the abutting member 211 at the tip of the pressure separating member 200 contacts the pressure roller 131, and the tip of the separation claw 201 is disposed in the vicinity of the surface of the pressure roller 131. Then, as the pressure roller 131 rotates, the separation claw 201 enters between the recording material and the pressure roller 131 to separate them.

  On the other hand, when a recording material that can be easily separated from the pressure roller 131 such as non-recycled paper or thick paper is passed, the control unit energizes the solenoid 208 to perform a pull operation. The pressure separation member 200 and the separation claw 201 are separated from the pressure roller 131, and the recording material is not separated.

  As described above, in the present embodiment, the contact / separation mechanism 210 causes the pressure separation member 200 to contact the pressure roller 131 when necessary (during double-sided paper passing), and when not necessary, the pressure roller 131. Can be separated from Therefore, the recording material wound around the pressure roller 131 can be separated while suppressing adverse effects such as sliding on the pressure roller 131.

  In this embodiment, the separation claw 201 is attached to the tip of the pressure separation member 200, and the separation claw 201 can follow the change in the surface position of the pressure roller 131 by the copying mechanism 212. As a result, even when the outer diameter of the pressure roller 131 expands due to heat during sheet passing or contracts due to aging, the recording material can be appropriately separated. Note that the position change due to the pressure depressurization operation of the pressure roller 131 can be handled by the contact / separation mechanism 210 of the pressure separation member 200.

  Furthermore, in the present embodiment, since the plurality of separation claws 201 are attached in the longitudinal direction of the pressure separation member 200, the behavior of the recording material during sheet passing and the change in the outer diameter shape of the pressure roller 131 due to use over time. Regardless, the recording material can be separated from the pressure roller 131.

  Furthermore, in this embodiment, in the unlikely event that the recording material is not separated and clogging occurs, if the pressure separating member 200 is separated from the pressure roller 131 by the contact / separation mechanism 210, all the separation claws 201 are also disposed. At the same time, it is separated from the pressure roller 131. This makes it easy to deal with the jam of the recording material.

  Although the solenoid 208 is used in the contact / separation mechanism 210, a cam mechanism, a power cylinder, or the like may be used instead. Further, the contact / separation mechanism 210 and the copying mechanism described in the present embodiment are examples. For example, the contact / separation mechanism may be a mechanism that separates the pressure separation member 200 itself instead of separating only the tip of the pressure separation member 200.

(Second Embodiment)
FIG. 6 is a schematic diagram showing a tip portion of the separation claw according to the second embodiment, and FIG. 7 is a schematic diagram showing an enlarged tip portion of the pressure separation member. 6 and FIG. 7 are the same as those in FIG. 4, and the same reference numerals are assigned to the same components, and detailed description thereof is omitted.

  In this embodiment, the separation claw 201 is lifted from the pressure roller 131 using compressed air, and the separation claw 201 and the pressure roller 131 are not in contact with each other.

  As shown in FIG. 6, a hole is provided in the separation claw 201 and the tube 216 is inserted. The separation claw 201 is made of a material having a very large number of pores such as a porous material, and compressed air is passed through the tube 216. Further, as shown in FIG. 7, the tube 216 is connected to a compressor (not shown) with the pressure separation member 200 being turned up.

  When the compressor is operated and compressed air is passed through the separation claw 201 through the tube 216, compressed gas is ejected from the pores of the separation claw 201. Thereby, the separation claw 201 can be floated from the surface of the pressure roller 131 on the order of several tens of μm.

  As a modification of the present embodiment, as shown in FIG. 8, a nozzle 217 that ejects compressed air may be provided at the tip of the tube 216, and the compressed air may be blown directly onto the separation claw 201. Even in this case, compressed air is ejected from the pores of the separation claw 201, and the separation claw 201 can be floated from the surface of the pressure roller 131.

  In the present embodiment, the separation claw 201 can be brought into non-contact with the pressure roller 131 by allowing compressed air to flow through or blowing the separation claw 201. Thereby, it is possible to prevent the image quality from being deteriorated due to the contact between the separation claw 201 and the pressure roller.

(Third embodiment)
FIG. 9A is a schematic diagram showing the tip of the separation claw according to the third embodiment, and FIG. 9B is a schematic diagram showing the separation claw as viewed from the direction of arrow A. FIG. 9, the same components as those in FIG. 5 are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the third embodiment, when the separation claw 201 is made of a porous material, the flow rate of the compressed air ejected from the plurality of pores of the separation claw 201 varies depending on the part. Therefore, in the present embodiment, as shown in FIG. 9A, a compressed gas flow path 221 is provided in the separation claw 201. Then, a tube 216 is attached to one end of the flow path 221 to allow compressed air to flow. By providing the flow path 221, the pressure of the compressed air acting on each of the pores 220 becomes substantially uniform, so that the flow rate of the air discharged from each of the pores 220 becomes almost uniform.

  In this embodiment, as shown in FIG. 9B, a moisture absorbent material 222 such as a short fiber is attached to the surface of the separation claw 201 (excluding the surface facing the pressure roller 131). The reason for attaching the hygroscopic material 222 is to prevent dew condensation that occurs on the pressure separating member 200 and the separating claws 201. Moisture contained in the recording material evaporates in the vicinity of the exit of the fixing nip N (see FIG. 2) and is likely to condense on the surface of the pressure separation member 200 and the like. Therefore, the moisture absorbing material 222 attached to the separation claw 201 absorbs dew condensation so that water droplets do not fall on the image of the recording material.

  If the first dew condensation is absorbed by the hygroscopic material 222, the hygroscopic material 222 can be dried by the radiant heat from the fixing belt 121. Therefore, the dew condensation occurring on the pressure separation member 200 and the separation claw 201 can be prevented. The hygroscopic material 222 may also be attached to the pressure separating member 200.

(Fourth embodiment)
In the second and third embodiments, the separation claw 201 can be brought into non-contact with the pressure roller 131 by using compressed gas. In this embodiment, the abutting member 211 at the tip of the pressure separating member 200 is made of a porous material like the separating claw 201 described in the third embodiment, a flow path is provided, and compressed gas is sent by a tube. Thereby, the abutting member 211 of the pressure separating member 200 can be brought out of contact with the pressure roller 131.

  If the separation claw 201 described in the third embodiment and the abutting member 211 of the present embodiment are used in combination, image quality deterioration caused by contact between the pressure separating roller 131 and the member that separates the recording material is prevented. be able to.

  Hereinafter, another embodiment of the fixing device to which the present invention can be applied will be described. Since the contents of the present invention are the same as those described above, only the configuration of the fixing device will be described.

  FIG. 10 is a schematic diagram according to another embodiment of the fixing device mounted on the image forming apparatus. As shown in FIG. 10, the fixing device 101 includes a fixing belt 121 as a fixing member, a heating roller 135 for heating the fixing belt 121, a fixing roller 136, a pressure roller 131 as a pressure member, and a tension roller. 137. The fixing device 101 includes a pressure separation member 200 that separates the paper S from the pressure roller 131.

  The heating roller 135 and the fixing roller 136 are disposed slightly apart in the radial direction, and the fixing belt 121 is looped between the two rollers. The fixing roller 136 is urged leftward by a small tension roller 137.

  The heating roller 135 has a plurality of heat sources 138 therein, and heats the fixing belt 121. The lower outer surface of the fixing roller 136 is in elastic contact with the upper outer surface of the pressure roller 131 via the fixing belt 121. The pressure roller 131 has an elastic layer (not shown) on the outer peripheral side.

  A sheet guide plate 140a is disposed on the upstream side so as to incline upward toward the contact portion (fixing nip portion) 139 between the pressure roller 131 and the fixing roller 136. On the other hand, a sheet guide plate 140b is disposed substantially horizontally on the downstream side. A sheet S is arranged on the upper surface of each sheet guide plate 140a, 140b.

  The pressure separation member 200 is disposed below the paper guide plate 140 b and separates the paper S from the pressure roller 131.

  The pressure roller 131 is separated from the fixing position to the retracted position or returned from the retracted position to the fixing position by a moving means (not shown) such as a cam member and a spring member or a plunger. In FIG. 10, the pressure roller 131 is urged obliquely upward to the contact portion (fixing nip portion) 139 and is in a pressure state against the fixing roller 136. When the pressure roller 131 in the retracted position is urged and returned to the fixing position, the pressure separation member 200 contacts the pressure roller 131 and follows the pressure roller 131 as it is. On the other hand, when the pressure roller 131 is depressurized and separated to the retracted position, the pressure separation member 200 is separated from the pressure roller 131.

  As mentioned above, although this invention was demonstrated based on the Example, this invention is not limited to this, It can change suitably within the scope of the present invention. As the fixing device and the image forming apparatus, any configuration can be adopted as long as the present invention is applicable. The image forming apparatus is not limited to a copying machine or a printer, but may be a facsimile machine or a multifunction machine having a plurality of functions.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 3 Feed roller 4 Registration roller pair 5 Secondary transfer roller 7 Discharge roller pair 8 Exposure apparatus 9Y, 9C, 9M, 9Bk Toner bottle 11 Intermediate transfer belt 12Y, 12C, 12M, 12Bk Primary transfer roller 13 Intermediate Transfer belt cleaning means 20Y, 20C, 20M, 20Bk Photoconductor 30Y, 30C, 30M, 30Bk Charging member 40Y, 40C, 40M, 40Bk Developing device 50Y, 50C, 50M, 50Bk Cleaning means 61 Sheet feeding device 72, 73 Support roller 100, 101 Fixing device 121 Fixing belt 122 Reflecting member 123 Nip forming member 124 Stay 125a, 125b, 125c Halogen heater 126 Fixing separation member 131 Pressure roller 132 Core wire 133 Elastic layer 134 Surface layer 135 Heating roller 135 Roller 136 Fixing roller 137 Tension roller 138 Heat source 139 Contact part (fixing nip part)
140a, 140b Paper guide plate 200 Pressure separation member 201 Separation claw 202 Strut plate 203, 213 Strut 204 Rotating shaft 205 Lever 206, 214 Spring 208 Solenoid 210 Contact / separation mechanism 211 Abutting member 212 Copying mechanism 216 Tube 217 Nozzle 220 Pore 221 Flow path 222 Hygroscopic material S Paper N Fixing nip

Japanese Patent No. 4818826

Claims (6)

A pressurizing member that forms a fixing nip portion between the fixing member and the fixing member, a heating unit that heats the fixing member, and a pressurizing mechanism that can be brought into contact with and separated from the pressing member by a contact / separation mechanism A separation member, and a separation claw attached to the pressure separation member capable of following a change in the surface position of the pressure member by a copying mechanism;
In a fixing device that fixes a recording material carrying an unfixed image through the fixing nip portion,
When performing double-sided sheet feeding of the recording material, the pressure separating member is brought into contact with the pressure member, and the recording material wound around the pressure member is separated from the pressure member by the separation claw. A fixing device.   The fixing device according to claim 1, wherein a plurality of the separation claws are attached in a longitudinal direction of the pressure separation member. It has a nozzle that ejects compressed air,
The fixing device according to claim 1, wherein the compressed air is blown to the separation claw by the nozzle, and the separation claw is floated from a surface of the pressure member.   The separation claw is formed of a porous material, a flow path through which compressed air flows is provided inside the separation claw, and a tube for sending the compressed air is attached to one end of the flow path, and the separation claw is removed from the tube. The compressed air is allowed to flow through the flow path to float the separation claw from the surface of the pressure member, and a moisture absorbing material is applied to the surface of the separation claw excluding the surface of the separation claw facing the pressure member. The fixing device according to claim 1, wherein the fixing device is provided. The pressure separating member includes an abutting member that comes into contact with the pressure member outside a paper passing range region of the pressure member;
The abutting member is formed of a porous material, a flow path through which compressed air flows is provided inside the abutting member, and a tube for sending the compressed air is attached to one end of the flow path, 5. The fixing device according to claim 1, wherein the compressed air is caused to flow through the flow path of the abutting member to float the abutting member from a surface of the pressure member. 6.   An image forming apparatus comprising the fixing device according to claim 1.

Images