JP2011069949A - Fixing device and image forming apparatus with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent accumulation of toner, which may cause soiled paper or image quality degradation, on separation pawls while maintaining the function of the separation pawls. <P>SOLUTION: The fixing device includes: a rotor 4 with which paper with a toner image transferred thereto comes into contact; the plurality of separation pawls 6 abutting on the rotor 4 and used for separating paper from the rotor 4; and a separating mechanism 8 for separating the separation pawls 6 from the positions where they abut on the rotor 4. When separating the separation pawls 6, the separating mechanism 8 makes at least one of the separation pawls 6 remain abutting on the rotor 4. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a fixing device that fixes a toner image transferred onto a sheet. The present invention also relates to an image forming apparatus such as a multifunction machine, a copying machine, a printer, and a facsimile machine that includes a fixing device.

  In general, an electrophotographic image forming apparatus (printer, multifunction machine, etc.) includes a fixing device that heats and pressurizes a toner image transferred onto a sheet. For example, the fixing device fixes the toner image by passing the paper on which the toner image has been transferred to the nip between the rotating body for heating the paper and the rotating body for pressurization that is in pressure contact with the rotating body for heating. However, the toner melted by heat has a property of sticking, and the paper may be wound around the rotating body. The wrapping of the paper causes a paper jam (clogging) in the fixing device, a paper fold or the like. Therefore, a separation claw that contacts the rotating body and separates (peels) the sheet from the rotating body may be provided in the vicinity of the sheet exit of the nip. An example of a fixing device having such a separation claw is described in Patent Document 1.

Specifically, Patent Document 1 includes a pressure roller and a heating roller that pressurize and heat a sheet on which a toner image is formed to fix the toner image, and a separation claw that separates the sheet after fixing from the heating roller. A fixing device is described in which a roller body for guiding the movement of a sheet is held by a holding member in the vicinity of a separation claw so that the roller can be rotated and can be displaced by a pressing force from the sheet. With this configuration, the roller body that guides the movement of the paper is displaced in response to the pressure from the paper and escapes, thereby eliminating pressure marks on the paper (Patent Document 1: Claim 1, FIG. 2, etc.) reference).
JP 2001-235958 A

  First, toner that could not be fixed on the sheet or toner that scatters in the image forming apparatus may adhere to the surface of the heating rotator or the pressure rotator. As described above, the separation claw is provided in contact with each rotating body in order to prevent the paper from being wound. The contact portion of the separation claw with the rotating body picks up toner on the surface of the rotating body and stores the toner. End up. In other words, the separation claw scrapes and collects the toner on the surface of the rotating body.

  As the toner accumulates, for example, it becomes a small lump. Since the separation claw comes into contact with the paper, the toner accumulated over a certain amount may spill out, adhere to the paper, and stain the paper. However, the separation claw is difficult to clean because it is located inside the machine. For this reason, only negative measures such as giving up even if the spilled toner adheres to the paper or reprinting after the influence of the spilled toner disappears can be taken. As described above, the spilled toner stains the paper and causes a decrease in image quality.

  Here, when Patent Document 1 is viewed, there is no description about the toner collecting on the separation claw. Therefore, the toner cannot accumulate in the contact portion between the separation claw and the rotator, and the spilled toner may contaminate the paper and cause a decrease in image quality.

  SUMMARY OF THE INVENTION In view of the above-described problems of the prior art, an object of the present invention is to prevent toner that causes paper contamination and image quality deterioration from being accumulated in the separation claw while maintaining the function of the separation claw.

  In order to solve the above-described problem, a fixing device according to a first aspect of the present invention includes a rotating body that contacts a sheet on which a toner image is transferred, and a plurality of separation claws that contact the rotating body and separate the sheet from the rotating body. The separation claw has a separation mechanism that separates the separation claw from a position where it comes into contact with the rotating body.

  According to this configuration, since the separation mechanism is provided, the separation claw can be separated from the position where it comes into contact with the rotating body. When the separation claw is separated, the accumulated toner is dragged by the rotation of the rotating body and is sent, so that the toner is removed from between the rotating body and the separation claw. The toner that has been sent falls from, for example, a rotating body. Thereby, it is possible to prevent toner from being accumulated between the separation claw and the rotating body. Accordingly, it is possible to provide a fixing device in which the toner is conspicuously accumulated on the sheet, and the sheet is not contaminated by the spilled toner and the image quality is not deteriorated.

  According to a second aspect of the present invention, in the first aspect of the invention, when the separation mechanism separates the separation claw, at least one of the plurality of separation claws is brought into contact with the rotating body. I decided to keep it.

  According to this configuration, when the separation claw is separated, at least one separation claw among the plurality of separation claws is kept in contact with the rotating body. However, the paper can be separated from the rotating body. That is, even if the separation claw is separated, the function of the separation claw is not impaired. As a result, it is possible to prevent the occurrence of jamming and folding of the paper due to the winding of the paper.

  The invention according to claim 3 has a plurality of support shafts for supporting the separation claw in the invention of claim 1 or 2, and the separation mechanism moves the support shaft to rotate the separation claw in the rotation direction. The support shaft is separated from the body, and at least one of the support shafts is not moved from the position.

  According to this configuration, when separating the separation claw, the separation mechanism does not move at least one of the support shafts. Therefore, whenever the paper is wound around the rotating body, the paper is removed from the rotating body. Can be separated. That is, even if the separation claw is separated, the function of the separation claw is not impaired. As a result, it is possible to prevent the occurrence of jamming and folding of the paper due to the winding of the paper. Further, the plurality of separation claws can be separated at a time by moving the support shaft.

  According to a fourth aspect of the present invention, in the invention of the third aspect, each of the support shafts is in contact with the rotating body within a region where the rotating body is in contact with a minimum size sheet that can pass through the fixing device. At least one separation claw is supported, and at least one separation claw is supported outside the region.

  According to this configuration, the support shaft supports the at least one separation claw so as to contact the rotating body within the region where the minimum size paper that can pass through the fixing device and the rotating body contact, and at least 1 outside the region. Since the two separation claws are supported, the sheet can be reliably separated from the rotating body even when the small-sized sheet is wound around the rotating body. In addition, since a sheet is separated by a two or more separation claws for a large size sheet, the sheet can be reliably separated from the rotating body.

  According to a fifth aspect of the present invention, in the first to fourth aspects of the invention, the separation mechanism includes a cam and / or a solenoid.

  According to this configuration, since the separation mechanism includes the cam and / or the solenoid, the separation claw can be separated from the rotating body with a simple configuration.

  According to a sixth aspect of the present invention, in the first to fifth aspects of the present invention, the separation mechanism may be configured such that the separation pawl is moved each time a predetermined number of sheets pass or the rotating body rotates a predetermined number of times. It was decided to separate.

  According to this configuration, for example, the separation mechanism separates the separation claw each time a predetermined number of sheets pass or the rotation of the rotation body a predetermined number of times, such as synchronizing the rotation of the separation mechanism and each rotation body. Therefore, the toner accumulated between the separation claw and the rotating body can be removed periodically. Thereby, it is possible to prevent toner from being accumulated between the separation claw and the rotating body.

  According to a seventh aspect of the present invention, in the third to sixth aspects of the invention, the rotating body is heated by a heating element, and a heating rotating body that heats a sheet onto which a toner image is transferred, and the heating rotation. One or both of the pressing rotary bodies that are in contact with the body and form a nip, and when the rotary body is both the heating rotary body and the pressing rotary body, The plurality of separation claws, the separation mechanism, and the plurality of support shafts are provided.

  According to this configuration, when a separation claw is provided, whether it is a heating rotator or a pressure rotator, between the separation claw and the heating rotator, or between the separation claw and the pressure rotator. It is possible to prevent toner from being accumulated in the toner.

  An image forming apparatus according to an eighth aspect includes the fixing device according to any one of the first to seventh aspects.

  According to this configuration, it is possible to provide an image forming apparatus that is free from jamming and paper folding due to paper winding. In addition, it is possible to provide an image forming apparatus in which the sheet is not soiled by the toner accumulated between the separation claw and the rotating body, and the image quality on the printed matter is high.

  According to a ninth aspect of the invention, there is provided the control unit according to the eighth aspect of the invention, wherein the control unit counts the number of pixels on the paper based on the image data to be printed, and the control unit applies the toner to the paper. When it is determined that the number of pixels to be exceeded exceeds a predetermined value, the separation mechanism separates the separation claw.

  The higher the toner concentration, the more toner adheres to each rotating body, and the toner tends to accumulate between the rotating body and the separation claw. When it is determined that the number of pixels to be exceeded has exceeded a predetermined value, the separation mechanism separates the separation claw, so that toner can be efficiently prevented from being collected between the separation claw and the rotating body.

  As described above, according to the present invention, it is possible to prevent toner from accumulating between the toner and the rotating body. Accordingly, after the accumulation, the paper is not soiled by the spilled toner and the image quality is not deteriorated. In addition, since all the separation claws are not separated at the same time, the function of separating the sheets is not impaired.

1 is a schematic cross-sectional view illustrating a schematic configuration of a multifunction machine according to a first embodiment. FIG. 3 is an enlarged cross-sectional view of one image forming unit according to the first embodiment. FIG. 2 is a block diagram illustrating an example of a hardware configuration of the multifunction peripheral according to the first embodiment. (A) is an expanded model sectional view showing an example of a fixing device according to the first embodiment, and (b) and (c) show an example of a separation claw. (A)-(e) is a model enlarged view for demonstrating an example of the operation | movement of the cam which concerns on 1st Embodiment, and the separation of a separation nail | claw. FIG. 3 is a schematic plan view of the fixing device as viewed from above for explaining an example of the separation mechanism according to the first embodiment. It is a block diagram which shows an example of the control system of the separation mechanism which concerns on 1st Embodiment. 6 is a flowchart illustrating an example of separation claw separation control in the multifunction peripheral according to the first embodiment. FIG. 6 is a schematic plan view of a fixing device as viewed from above for explaining an example of a separation mechanism according to a second embodiment.

  Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. However, each element such as configuration and arrangement described in the description of each embodiment does not limit the scope of the invention and is merely an illustrative example.

(Schematic configuration of image forming apparatus)
First, an outline of a multifunction peripheral 100 (corresponding to an image forming apparatus) according to the first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a schematic cross-sectional view showing a schematic configuration of a multifunction peripheral 100 according to the first embodiment of the present invention. FIG. 2 is an enlarged sectional view of one image forming unit 25 according to the first embodiment of the present invention.

  As shown in FIG. 1, the multifunction peripheral 100 according to the present embodiment includes a document conveying device 110 and an image reading unit 120 at an upper portion, and an operation panel 130 at an upper front portion. In the main body, a paper feed unit 2a, a conveyance path 2b, an image forming unit 2c, an intermediate transfer unit 3a, a fixing device 1, a conveyance path 3b for duplex printing, and the like are provided.

  When copying a document, the document transport device 110 automatically and continuously feeds the documents stacked on the document loading tray 111 one by one toward the reading position of the image reading unit 120 (feed reading contact glass 121). Transport. The image reading unit 120 reads a document and generates image data. A feed reading contact glass 121 and a placement reading contact glass 122 are provided on the upper surface of the image reading unit 120, and an optical system member such as an exposure lamp, a mirror, a lens, and an image sensor (for example, CCD) is provided in the image reading unit 120. (Not shown) is provided.

  Then, using these optical system members, the image reading unit 120 irradiates the document conveyed by the document conveying device 110 or the document on the placement reading contact glass 122 and receives the reflected light of the document. Image data is generated by A / D converting the output value of each pixel of the image sensor. The multi-function device 100 can perform printing based on the obtained image data (copy function). The document conveying device 110 is provided with a fulcrum on the back side of the paper surface of FIG. 1 and can be lifted. After the document is placed on the placement reading contact glass 122, the document conveying device 110 presses the document. The operation panel 130 includes a touch panel type liquid crystal display unit 131 and various keys, and receives a display of the status (for example, error occurrence and mode) of the multifunction device 100 and various inputs from the user.

  The paper feed unit 2a accommodates various sizes of sheets (sheets) such as copy sheets and label sheets. The paper feed unit 2a then feeds the paper to the transport path 2b and supplies the paper. The conveyance path 2 b guides the sheet supplied from the sheet feeding unit 2 a and conveyed in the multifunction peripheral 100 to the discharge tray 21 through the intermediate transfer unit 3 a and the fixing device 1. The conveyance path 2b is supplied with a driving force from a conveyance motor (not shown) or the like, and is conveyed with a pair of conveyance rollers 22a to 22c (in FIG. 1, the reference numerals are given in order from the top). There are provided a registration roller pair 23 for waiting the sheet in front of the intermediate transfer unit 3 a and feeding it at the same timing, a discharge roller pair 24 for discharging the sheet to the discharge tray 21, and the like.

  Furthermore, the multifunction peripheral 100 includes an image forming unit 25 and an exposure device 26 for four colors as an image forming unit 2c that forms a toner image based on image data. Specifically, as a portion for forming a toner image, the multifunction peripheral 100 forms a cyan image from an image forming unit 25Bk that forms a black image, an image forming unit 25Y that forms a yellow image, from the left side of FIG. In addition to an image forming unit 25C for forming a magenta image, an exposure device 26 is provided.

  Here, the image forming units 25Bk to 25M will be described in detail with reference to FIG. Each of the image forming units 25Bk to 25M is different in toner color, but all have basically the same configuration and can be described in the same manner. Therefore, only one image forming unit 25 is shown in FIG. 2, and in the following description, unless otherwise specified, Bk (black), Y (yellow), which are codes for identifying the colors of the image forming units 25, The symbols C (cyan) and M (magenta) are omitted.

  First, each photosensitive drum 27 carries a toner image on its peripheral surface, and is rotated counterclockwise on a paper surface at a predetermined process speed by a driving mechanism. Each charging device 28 charges the photosensitive drum 27 at a constant potential. An exposure device 26 below each image forming unit 25 (see FIG. 1) converts the color-separated image signal into an optical signal by a laser output unit (not shown), and a laser beam as an optical signal ( 4) can be output for four colors, and the photosensitive drum 27 after scanning is subjected to scanning exposure to form an electrostatic latent image.

  Each developing device 29 stores a developer (not shown) containing toner (the image forming unit 25Bk has black, the image forming unit 25Y has yellow, the image forming unit 25C has cyan, and the image forming unit 25M. The one contains magenta developer). Each developing device 29 carries toner, and supplies the toner to the photosensitive drum 27 when a toner image is formed. As a result, the electrostatic latent image is developed as a toner image. Each cleaning device 29a cleans the surface of the photosensitive drum 27.

  Returning to FIG. The intermediate transfer unit 3 a receives the primary transfer of the toner image from the photosensitive drum 27 and performs the secondary transfer on the paper. The intermediate transfer unit 3a is stretched around, for example, each primary transfer roller 30 (a total of four from 30Bk to 30M) provided in a pair with the photosensitive drum 27, a driving roller 31, driven rollers 32 and 33, and each roller. And an endless intermediate transfer belt 34, a secondary transfer roller 35, a belt cleaning device 36, and the like. Each primary transfer roller 30 abuts on the intermediate transfer belt 34 so as to sandwich each photosensitive drum 27 and the endless intermediate transfer belt 34. The toner image is transferred to the intermediate transfer belt 34 by applying a transfer voltage to each primary transfer roller 30.

  The intermediate transfer belt 34 circulates in the clockwise direction in FIG. 1 by the rotational drive of a driving roller 31 connected to a driving mechanism such as a motor. The secondary transfer roller 35 sandwiches the driving roller 31 and the intermediate transfer belt 34. The toner image (black, yellow, cyan, and magenta colors) superimposed on the intermediate transfer belt 34 without deviation is transferred onto the sheet at the nip between the secondary transfer roller 35 and the intermediate transfer belt 34 to which a predetermined voltage is applied. The The belt cleaning device 36 removes and collects residual toner and the like on the intermediate transfer belt 34 after the secondary transfer.

  The fixing device 1 heats and pressurizes the toner image secondarily transferred onto the paper and fixes the toner image. In order to avoid clutter, a part of the configuration of the fixing device 1 is not shown in FIG. The fixing device 1 has a built-in heater 11 and is in pressure contact with a heating roller 4 (corresponding to a rotating body and a heating rotating body) with which a sheet on which a toner image has been transferred contacts, thereby forming a nip, and a toner image Including a pressure roller 5 (corresponding to a rotating body and a pressing rotating body) with which the sheet on which the toner is transferred contacts. The sheet is heated and pressurized when passing through the nip, and the toner image is fixed on the sheet.

  Furthermore, the multifunction peripheral 100 of the present embodiment includes a duplex printing conveyance path 3b for duplex printing. The duplex printing conveyance path 3 b connects the conveyance path 2 b upstream of the registration roller pair 23 from the conveyance path 2 b downstream of the fixing device 1 in the sheet conveyance direction. Further, the duplex printing conveyance path 3b is provided between a pair of conveyance rollers 37a to 37c that are rotationally driven for conveyance of the sheet, and between the fixing device 1 and the discharge roller pair 24, and a switching valve 38 for determining the conveyance direction of the sheet. Etc.

  During double-sided printing, a switchback operation is performed to reverse the front and back of the single-sided printed paper. In the switchback operation, the single-sided printed paper is conveyed in the direction of being discharged to the discharge tray 21 by the discharge roller pair 24. At this time, the switching valve 38 is rotated to a position for guiding the sheet to the discharge roller pair 24. Next, the rotation direction of the discharge roller pair 24 is reversed before the discharge roller pair 24 has discharged the single-side printed paper. At this time, the switching valve 38 is in a position for guiding the sheet to the duplex printing conveyance path 3b.

  Thereafter, the single-side printed paper is transported to the duplex printing transport path 3b, transported to the upstream side of the registration roller pair 23, and joins the transport path 2b. Further, the one-side printed paper is sent out from the registration roller pair 23, the toner image is transferred, and the toner image is fixed by the fixing device 1. The paper printed on both sides is discharged to the discharge tray 21.

  A plurality of paper sensors S for detecting passage and arrival of paper can be provided in the transport path 2b and the duplex printing transport path 3b (reference numerals S1 to S4 are attached from above). The sheet sensors S1 to S4 are, for example, optical sensors, and the output changes depending on whether or not a sheet exists in the detection area. The output of each paper sensor S is input to a control unit 10 to be described later, and the control unit 10 can grasp the conveyance status of the paper, the number of sheets that have passed through the fixing device 1, and the like based on the output of the paper sensor S. .

(Hardware configuration of MFP 100)
Next, an example of the hardware configuration of the multifunction peripheral 100 according to the first embodiment of the present invention will be described with reference to FIG. FIG. 3 is a block diagram illustrating an example of a hardware configuration of the multifunction peripheral 100 according to the first embodiment of the present invention.

  First, as illustrated in FIG. 3, the MFP 100 according to the present embodiment is provided with a control unit 10 that controls the operation of the MFP 100. In FIG. 3, the control unit 10 is illustrated as one, but the control unit 10 is an engine that controls ON / OFF of a main control unit that performs control and image processing and a motor that rotates various rotating bodies. A plurality of types may be provided by dividing each function such as a control unit.

  The control unit 10 includes a CPU 101 as a central processing unit. The storage unit 102 includes a RAM, a ROM, a flash ROM, an HDD, and the like. For example, the storage unit 102 stores programs and data necessary for performing various controls, and temporarily expands and stores control programs and data, image data, and the like. In addition, the control unit 10 can be provided with a time measuring unit 103 that measures various control times. Further, regarding the implementation of the present invention, the storage unit 102 also stores data, a program, and the like related to the control of the separation mechanism 15 that separates the separation claws 6A and 6B of the fixing device 1 from the heating roller 4 and the pressure roller 5. In addition, the control unit 10 can count the number of pixels on which the toner is applied based on the image data to be printed.

  The control unit 10 is connected to the document conveying device 110, the image reading unit 120, the paper feeding unit 2a, the conveying path 2b, the image forming unit 2c, the fixing device 1, the duplex printing conveying path 3b, the power supply device 140, and the like. Control the operation of each part. In addition, an I / F unit 150 (interface unit) is attached to or connected to the control unit 10. The multi-function device 100 is connected to an external computer 200 (for example, a personal computer) via a network or the like using the I / F unit 150. As a result, the multifunction peripheral 100 can perform printing by receiving transmission of image data and print setting data from the external computer 200 (printer function). In addition, the I / F unit 150 can include a modem function, send / receive data to / from the other party's FAX apparatus 300 via a public line, or print based on received data (FAX function).

  The power supply device 140 is connected to, for example, a commercial power supply, supplies power to the commercial power supply to the heater 11, performs rectification, step-down, and the like of the heater 10, and voltage for devices such as the control unit 10 (for example, DC5V, 3. 3V or the like) and a motor driving voltage (for example, DC 24V) are generated and supplied.

  The control unit 10 is connected to a temperature sensor 12 disposed in the fixing device 1 for measuring the temperature of the heating roller 4 through a signal line L, and recognizes the temperature of the heating roller 4 based on the output voltage of the temperature sensor 12. To do. Then, the control unit 10 maintains the temperature of the heating roller 4 at the fixing control temperature with a heater drive control signal, except in the power saving mode (for example, sleep mode), based on the grasped temperature of the heating roller 4. Thus, the heater 11 is controlled to be turned on / off. The “fixing control temperature” is the temperature of the heating roller 4 that is to be maintained during printing, and is a temperature that is suitable for fixing a toner image (for example, 150 ° C. to 200 ° C., which varies depending on the model). .

  As shown in FIG. 3, in the multifunction peripheral 100 according to the present embodiment, the fixing device 1 includes a heating circuit 13 for energizing the heater 11 built in the heating roller 4. The heating circuit 13 is connected to a switch 14 for switching ON / OFF of energization to the heater 11. The switch 14 is connected to a heater control signal line HS from the CPU 101, and the CPU 101 inputs a signal instructing ON / OFF control of energization to the heater 11 through the heater control signal line HS to the switch 14. Thereby, the energization to the heater 11 is turned ON / OFF.

  Further, regarding the fixing device 1, the control unit 10 can control ON / OFF of the fixing motor 16 for rotating the heating roller 4 and the pressure roller 5. For example, the control unit 10 rotates the fixing motor 16 during printing or when the temperature of the heating roller 4 is made uniform. Further, the control unit 10 is provided in the fixing device 1 and can also control a separation mechanism 15 that makes the separation claws 6A and 6B abut against or separate from the heating roller 4 and the pressure roller 5 (of the separation mechanism 15). Details will be described later).

(Configuration of Fixing Device 1)
Next, an example of the fixing device 1 according to the first embodiment of the present invention will be described in detail with reference to FIG. FIG. 4A is an enlarged schematic cross-sectional view illustrating an example of the fixing device 1 according to the first embodiment of the present invention, and FIGS. 4B and C illustrate examples of the separation claws 6A and 6B. . Note that a two-dot chain line in FIG. 4A indicates the sheet conveyance direction.

  First, as shown in FIG. 4A, a heating roller 4 incorporating a heater 11 is provided in the fixing device 1. For example, the cylindrical portion 41 of the heating roller 4 is made of metal (for example, iron), and the heating roller shaft 42 protrudes from both ends of the cylindrical portion 41. Driving from the fixing motor 16 is transmitted to the heating roller shaft 42 (see FIG. 3, illustration of the transmission mechanism is omitted). Further, the temperature sensor 12 is provided so as to contact the heating roller 4 on the right side when viewed from the front.

  A pressure roller 5 is provided in contact with the heating roller 4 in the fixing device 1. For example, the cylindrical portion 51 of the pressure roller 5 is formed of a material that is more elastic than the heating roller 4, such as rubber or sponge, from the viewpoint of increasing the pressure applied at the nip. The pressure roller 5 also has a roller shaft (pressure roller shaft 52). For example, as shown in FIG. 4A, an elastic body 53 (for example, a spring) is connected to the pressure roller shaft 52. The other end of the elastic body 53 is connected to a housing, a frame, and the like of the fixing device 1, and the elastic body 53 urges the pressure roller 5 in the direction of the heating roller 4 (the urging direction is indicated by a broken line arrow). With these configurations, heat and pressure are applied to the nip between the heating roller 4 and the pressure roller 5, and the toner image passing through the nip is fixed on the sheet.

  Here, the toner image transferred by the intermediate transfer portion 3 a contacts the heating roller 4. Since the melted toner has adhesiveness, the paper may be wound around the heating roller 4. In the fixing device 1, a cleaning device 17 including a blade 17 a that contacts the heating roller 4 and scrapes the adhered toner can be provided. However, the toner attached to the heating roller 4 adheres firmly and is cleaned. In some cases, the device 17 is difficult to remove. The toner that adheres firmly also has adhesiveness, which may contribute to the paper winding around the heating roller 4. The wound paper tries to rotate with the heating roller 4. As a result, a paper jam occurs.

  Therefore, in order to prevent jamming due to the wrapping of the paper, a plurality of separation claws 6 that contact each roller and separate the paper from each roller (reference numerals 6A for the heating roller and 6B for the heating roller). In the case of being explained in common, A and B for identification may be omitted). The separation claw 6 </ b> A is provided at a position on the paper exit side in the nip between the heating roller 4 and the pressure roller 5. In the example of FIG. 4, the separation claw 6 </ b> A contacts the heating roller 4 at the upper part of the heating roller 4.

  As shown in FIG. 4A, in the multi-function device 100 of this embodiment, the pressure roller 5 is also in contact with a plurality of separation claws 6B for the pressure roller. The separation claw 6 </ b> B is provided at a position on the paper exit side in the nip between the heating roller 4 and the pressure roller 5. In the example of FIG. 4, the separation claw 6 </ b> B of the pressure roller 5 is also in contact with the pressure roller 5 above the pressure roller 5.

  In particular, when fixing the toner image on the back surface in double-sided printing, the paper may wrap around the pressure roller 5 due to the adhesiveness of the default toner on the surface of the paper on the pressure roller 5 side. Further, for example, toner scattered in the machine may adhere to the pressure roller 5. Note that the pressure roller 5 can also be provided with a cleaning device 18 including a blade 18a that contacts the pressure roller 5 and scrapes off adhering toner. However, the toner adhering to the pressure roller 5 may adhere firmly and may be difficult to remove. The toner that adheres firmly also has adhesiveness, which may contribute to the paper being wound around the pressure roller 5. As described above, a jam or the like accompanying the winding of the paper also occurs in the pressure roller 5, so that the plurality of separation claws 6 </ b> B come into contact with the pressure roller 5.

  An example of each separation claw 6 (6A, 6B) is shown in FIGS. 4 (b) and 4 (c). Each separation claw 6 that contacts the heating roller 4 and the pressure roller 5 only needs to be able to separate the paper. Therefore, each separation claw 6 may have a wedge shape, for example, as shown in FIG. As shown in FIG.4 (c), it is good also as a square-cone shape. Each separation claw 6 is laid down, and the abdomen portion of each separation claw 6 abuts. For example, the lower surface of each separation claw 6 is in contact with each roller so as to coincide with the circumferential tangent of each roller. Then, the front of the wound paper rides over each separation claw 6 and the paper is separated (separated) from each roller.

  And each separation nail | claw 6 (6A, 6B) is provided with the through-hole 61 penetrated to the side surface which opposes from one side surface. A support shaft 7 for supporting the separation claws 6A, 6B (7A for the heating roller, 7B for the pressure roller, and 7B for the pressure roller. (A and B for identification may be omitted.) Are inserted. Each separation claw 6 may be fixedly attached to each support shaft 7 (7A, 7B), or may be attached so as to be able to swing by a certain angle in the vertical direction. Then, by supporting each support shaft 7 above the heating roller 4 and the pressure roller 5, each separation claw 6 comes into contact with each roller.

  Further, a cam 8 (a part of the separation mechanism 15) is provided at a side position in the axial direction of the heating roller 4 and the pressure roller 5 (8A for the heating roller, and cam 8B for the pressure roller. (If there is a common explanation, A and B for identification may be omitted.) The cam 8 </ b> A rotates to lift the support shaft 7 </ b> A and separate the separation claw 6 </ b> A from the heating roller 4. The cam 8B rotates to lift the support shaft 7B and separate the separation claw 6B from each roller. In other words, each support shaft 7 (7A, 7B) moves upward (for example, the moving direction is guided by a guide or the like), and each support shaft 7 is moved to move each separation claw 6 (6A, 6B). ) Can be separated. Therefore, next, the operation of each cam 8 and the separation of each separation claw 6 will be described.

(Operation of cam 8 and separation of separation claw 6)
Next, an example of the operation of the cam 8 and the separation of the separation claw 6 according to the first embodiment of the present invention will be described based on FIG. FIGS. 5A to 5E are schematic enlarged views for explaining an example of the operation of the cam 8 and the separation of the separation claw 6 according to the first embodiment of the present invention. FIG. 5 shows the surface of the heating roller 4, a separation claw 6 </ b> A that contacts the heating roller 4, and a support shaft 7 </ b> A that supports the separation claw 6 </ b> A. The same applies to the pressure roller 5 side.

  First, when the cam 8A rotates, the side surface of the cam 8A hits the one support shaft 7A (FIG. 5A). Further, when the cam 8A continues to rotate, the one support shaft 7A continues to be lifted (FIG. 5B). As a result, the separation claw 6A supported by the one support shaft 7A is separated from the surface of the heating roller 4. When the cam 8A continues to rotate, the one support shaft 7A and the cam 8A are not in contact with each other, and the one support shaft 7A returns to the position where the separation claw 6A contacts the heating roller 4 (FIG. 5C). . One support shaft 7A may return by its own weight, or may be biased downward by a biasing member (for example, a spring, not shown).

  When the cam 8A continues to rotate, the cam 8A comes into contact with the other support shaft 7A and further lifts the other support shaft 7A (FIG. 5D). As a result, the separation claw 6A supported by the one support shaft 7A is separated from the surface of the heating roller 4. Further, when the cam 8A continues to rotate, the other support shaft 7A and the cam 8A are not in contact with each other, and the other support shaft 7A returns to a position where the separation claw 6A contacts the heating roller 4 (FIG. 5 (e)). . The other support shaft 7A may be returned by its own weight or may be biased downward by a biasing member (for example, a spring, not shown).

  That is, when separating the separation claw 6, the separation mechanism 15 keeps at least one separation claw 6 out of the plurality of separation claws 6 in contact with the rotating body (the heating roller 4 and the pressure roller 5). The separation mechanism 15 has a plurality of support shafts 7 that support the separation claw 6, and the separation mechanism 15 moves the support shaft 7 to separate the separation claw 6 from the rotating body, and at least one of the support shafts 7 is supported. 7 is not moved from the position. Thereby, at least one separation claw 6 can always be kept in contact with each roller. Therefore, the paper can be separated regardless of the timing of the winding of the paper.

(Separation mechanism 15)
Next, an example of the separation mechanism 15 according to the first embodiment of the present invention will be described based on FIGS. 6 and 7. FIG. 6 is a schematic plan view of the fixing device 1 as viewed from above for explaining an example of the separation mechanism 15 according to the first embodiment of the present invention. FIG. 7 is a block diagram illustrating an example of a control system of the separation mechanism 15 according to the first embodiment of the present invention. The separation mechanism 15 separates the separation claws 6 </ b> A and 6 </ b> B from positions where they contact each roller (rotating body). Further, as will be described below, the separation mechanism 15 includes a cam 8 or a solenoid 9.

  As described above, in the present embodiment, each separation claw 6 comes into contact with each roller (the heating roller 4 or the pressure roller 5), and thus each separation claw 6 scrapes off the toner on the surface of each roller. Therefore, toner accumulates between each separation claw 6 and each roller. The accumulated toner spills out when the separation claws 6 come into contact with the paper or when the separation claws 6 cannot be supported. The spilled toner adheres to the paper and may stain the paper. Therefore, the fixing device 1 according to the present embodiment separates the separation claws 6 from the rollers so that the toner does not accumulate between the separation claws 6 and the rollers so that the toner is recognized as dirt on the paper. Have

  For example, when the separation claws 6 are separated from each other, the toner between the separation claws 6 and the rollers is attracted by the rotation of the rollers. And it is scraped off by the blade 17a or the blade 18a. Alternatively, it falls into the machine as a small amount of toner lump. Accordingly, it is possible to prevent the paper from being greatly soiled by the accumulated toner.

  First, FIG. 6 shows an example in which the heating roller 4 is arranged on the right and the pressure roller 5 is arranged on the left. In contrast to FIG. 1, the lower side of FIG. 6 is the front side. Two support shafts 7A are provided above the heating roller 4. Two separation claws 6A are attached to the two support shafts 7A. On the other hand, two support shafts 7B are also provided above the pressure roller 5, and two separation claws 6B are attached thereto. That is, in the fixing device 1, four support shafts 7 and eight separation claws 6 are provided.

  In FIG. 6, when the minimum size paper that can be passed by the fixing device 1 (that can be used for printing by the multifunction peripheral 100) is fixed, the heating roller 4 and the pressure roller 5 pass through the shaded area. This is an area that contacts a minimum size sheet (shown as area F1). The non-shaded area is an area where the heating roller 4 and the pressure roller 5 do not contact the minimum size paper when the minimum size paper is fixed (illustrated as an area F2). In the present embodiment, the sheet is transported so that the center of the heating roller 4 or the pressure roller 5 and the center of the sheet coincide (center passing). One separation claw 6 is provided for each support shaft 7 in each of the regions F1 and F2. As a result, even when a sheet having a range of not less than the minimum size and not more than the maximum size capable of passing the paper is wound around the heating roller 4 or the pressure roller 5, the separation can be reliably performed. That is, each support shaft 7 supports at least one separation claw 6 so as to contact the rotating body in a region where the minimum size paper that can pass through the fixing device 1 and the rotating body contact, and outside the region, at least 1 Two separating claws 6 are supported.

  Looking at the heating roller 4 side, cams 8 </ b> A as separating mechanisms 15 that lift (move) the support shaft 7 </ b> A are provided at both ends in the axial direction of the heating roller 4. If only one cam 8A can lift the support shaft 7A sufficiently, one cam 8A may be provided for each heating roller 4. Further, when two cams 8A are provided for the heating roller 4, their rotation angles are the same.

  On the other hand, when viewed from the pressure roller 5 side, similarly to the heating roller 4, cams 8 </ b> B as separation mechanisms 15 that lift the support shaft 7 </ b> B are provided at both ends in the axial direction of the pressure roller 5. If only one cam 8B can lift the support shaft 7B sufficiently, one cam 8B may be provided for each pressure roller 5. Further, even when the pressure roller 5 is provided with two cams 8B, the rotation angles thereof are the same.

  The rotating shafts 81 of the two cams 8A are connected to the movable iron cores of the solenoids 9A and 9B for the heating roller, respectively. The rotating shafts 81 of the two cams 8B are connected to the movable iron cores of the pressure roller solenoids 9C and 9D, respectively. For example, the solenoids 9A to 9D are of a push type. The solenoids 9A to 9D move the cams 8A and 8B to be connected to the support shafts 7A and 7B when a current flows (when turned on). In FIG. 6, the solenoids 9 </ b> A to 9 </ b> D move the cams 8 toward the center of the heating roller 4 and the pressure roller 5. A recovery spring (invisible) is provided in the solenoids 9A to 9D, and when the current is cut off (turned off), the connected cams 8A and 8B are moved to positions where they do not come into contact with the support shafts 7A and 7B.

  FIG. 6 shows a state where the heating roller solenoids 9A and 9B are OFF and the heating roller cam 8A is retracted. Further, the pressure roller solenoids 9C and 9D are in the ON state, and the pressure roller cam 8B moves the support shaft 7B.

  Here, an example of a control system in the separation mechanism 15 will be described with reference to FIG. For example, as the separation mechanism 15, a separation mechanism control unit 151 that is connected to the control unit 10 and controls ON / OFF of the solenoids 9 </ b> A to 9 </ b> D is provided inside or outside the fixing device 1. The separation mechanism control unit 151 is connected to switch units 152 to 155 for turning on / off each solenoid 9. In addition, although a semiconductor switch etc. can be used for the switch parts 152-155, for example, what functions as an ON / OFF switch of each solenoid 9 should just be used.

  And the control part 10 can instruct | indicate to the separation mechanism control part 151 (indirectly), and can control the position of each cam 8 (8A, 8B). Therefore, the control part 10 can control the implementation timing of separation of each separation claw 6 (6A, 6B). The controller 10 may directly control ON / OFF of the solenoids 9A to 9D. In this case, the separation mechanism controller 151 is not necessary. For example, a power supply device 140 is connected to each of the switch units 152 to 155, and power for supply to each solenoid 9 is applied. Then, a current flows through the solenoid 9 corresponding to the switch units 152 to 155 which are turned on, and no current flows through the solenoid 9 corresponding to the switch units 152 to 155 which is turned off.

  A gear 82 is connected to the rotation shaft 81 of the cam 8A. A gear 83 is connected to the heating roller shaft 42. And the drive transmission member 84 which meshes with both the gear 82 and the gear 83 is connected. Thereby, if the heating roller 4 rotates, the cam 8A rotates. Accordingly, the separation mechanism 15 of the separation claw 6A of the heating roller 4 corresponds to the cam 8A, the gears 82 and 83, the drive transmission member 84, and the like. Although the drive transmission system is not shown in FIG. 6, the heating roller 4 is rotated by the fixing motor 16 as described in FIG.

  A gear 85 is connected to the rotation shaft 81 of the cam 8B. A gear 86 is also connected to the pressure roller shaft 52. And the drive transmission member 87 which meshes with both the gear 85 and the gear 86 is connected. In the cam 8B of the pressure roller 5, when the pressure roller 5 is rotated by the gear 85, the gear 86, and the drive transmission member 87, the cam 8B is also rotated. Accordingly, the separation mechanism 15 of the separation claw 6B of the pressure roller 5 corresponds to the cam 8B, the gears 85 and 86, the drive transmission member 87, and the like. In FIG. 6, the pressure roller 5 is in pressure contact with the heating roller 4. Therefore, when the heating roller 4 rotates, the pressure roller 5 also rotates. It should be noted that the pressure roller 5 may be rotated in response to transmission of driving from the fixing motor 16.

  In other words, the rotating body in the fixing device 1 is heated by a heating element (heater 11) and is in contact with the heating roller 4 (heating rotating body) that heats the sheet on which the toner image is transferred, and the nip. When one or both of the pressure rollers 5 (rotating body for pressure) to be formed and the rotating body is both the rotating body for heating and the rotating body for pressure, a plurality of separations are performed for each rotating body. A claw 6, a separation mechanism 15, and a plurality of support shafts 7 are provided.

(Separation control)
Next, an example of the separation control of the separation claw 6 in the multifunction machine 100 according to the first embodiment of the present invention will be described based on FIG. FIG. 8 is a flowchart illustrating an example of the separation control of the separation claw 6 in the multifunction peripheral 100 according to the first embodiment of the present invention. The separation claw 6 may be separated by the heating roller 4 and the pressure roller 5 at the same timing. However, in the following, the heating roller 4 is the heating roller 4, the pressure roller 5 is the pressure roller 5, An example having a criterion for determining whether or not to separate the separation claw 6B will be described.

  For example, the start in FIG. 8 is when printing starts. The MFP 100 according to the present embodiment performs printing when the image reading unit 120 functions as a copy, a printer, or a FAX. After starting printing, the controller 10 turns on the fixing motor 16 and rotates the heating roller 4 and the pressure roller 5 (step # 1). In addition, paper feeding and toner image formation are performed (step # 2). Then, the control unit 10 confirms whether the separation claws 6A and 6B are separated (step # 3).

  Specifically, the controller 10 determines whether or not to separate the separation claws 6A and 6B, for example, a predetermined number of sheets on which the toner image has been transferred to the fixing device 1 from the separation of the previous separation claws 6A and 6B. It can be determined based on whether or not. The “predetermined number” can be determined as appropriate based on the ease of toner accumulation in the separation claws 6A and 6B. If the predetermined number of values are different between the heating roller 4 and the pressure roller 5, the separation claw 6 is separated separately by the heating roller 4 and the pressure roller 5. Note that the heating roller 4 and the pressure roller 5 may have the same number of values. In this case, the separation claw 6 is separated by the heating roller 4 and the pressure roller 5 at the same timing.

  For example, in an experiment or the like, after the separation claws 6A and 6B are separated, the average number of sheets until the toner accumulated on the separation claws 6A and 6B spills is grasped by the heating roller 4 and the pressure roller 5, respectively. Or less than the average number obtained (for example, several to several tens). The control unit 10 can detect the passage of the sheet in the fixing device 1 based on each sheet sensor S.

  Further, the controller 10 determines whether or not the separation claws 6A and 6B are separated, for example, whether or not the heating roller 4 or the pressure roller 5 is rotated a predetermined number of times from the separation of the previous separation claws 6A and 6B. Can be judged. The “predetermined number of times” can also be determined as appropriate based on the ease of toner accumulation in the separation claws 6A and 6B. Even if the heating roller 4 and the pressure roller 5 have different values for the predetermined number of times, the heating roller 4 and the pressure roller 5 have different diameters. In some cases, the separation claw 6 may be separated by the heating roller 4 and the pressure roller 5 at the same timing. Therefore, the heating roller 4 and the pressure roller 5 may have the same or different values for a predetermined number of times.

  For example, the average number of rotations of the heating roller 4 and the pressure roller 5 until the toner accumulated in the separation claws 6A and 6B is spilled after the separation claws 6A and 6B are separated from each other is determined in advance through experiments or the like. For example, the predetermined number of times can be equal to or less than the grasped average number of rotations (for example, several to several tens of times). Here, the time required for one rotation of the heating roller 4 and the pressure roller 5 can be grasped in advance. The controller 10 rotates the heating roller 4 and the pressure roller 5 (step # 1), and the number of rotations of the heating roller 4 and the pressure roller 5 based on the elapsed time (for example, the time counting unit 103 measures time). Can be grasped. That is, the separation mechanism 15 (each cam 8, each solenoid 9, each gear, and each drive transmission member) separates the separation claw 6 every time a predetermined number of sheets pass or a roller rotates a predetermined number of times. .

  Further, the controller 10 can determine whether or not the separation claws 6A and 6B are separated based on, for example, whether or not the number of pixels on which toner is placed in the formed toner image exceeds a predetermined value. For example, when the surface is printed, if the amount of toner placed on the surface is large, the amount of toner attached to the heating roller 4 can be large. Also, if the amount of toner on the front surface is large during duplex printing, the amount of toner attached to the pressure roller 5 during printing on the back surface can be large. In these cases, toner can easily collect in the separation claws 6A and 6B.

  Therefore, when functioning as a copy, printer, or FAX, the control unit 10 counts the number of pixels on which toner is placed (pixel count) based on image data, and determines whether or not the separation claws 6A and 6B are based on whether or not a predetermined value is exceeded. Whether or not to be separated. Further, the heating roller 4 and the pressure roller 5 may have the same predetermined value or different values. If different, the separation claw 6 may be separated on the one hand and not separated on the other hand. Further, if the number of pixels on which toner is placed is too large, the separation claw 6 may be separated in both cases. That is, when the control unit 10 determines that the number of pixels on which the toner is applied exceeds a predetermined value, the separation mechanism 15 separates the separation claw 6.

  Further, the control unit 10 may determine whether to separate the separation claws 6A and 6B based on one of the above criteria (predetermined number of sheets, predetermined number of times, predetermined value). Further, the control unit 10 may determine that the separation claws 6A and 6B are separated if any one of the above-mentioned criteria (predetermined number of sheets, predetermined number of times, predetermined value) is exceeded. Further, the control unit 10 combines two of the above-mentioned standards (predetermined number, predetermined number of times, predetermined value) (for example, the predetermined number of sheets and a predetermined value), and separates the separation claws 6A and 6B if one criterion is exceeded. You may decide to make it.

  If the control unit 10 determines that the separation claws 6A and 6B are to be separated (Yes in step # 3), the control unit 10 is connected to the cam 8 corresponding to the separation claw 6 that is determined to be separated. To move the cam 8 (step # 4). For example, when it is determined that only the separation claw 6A for the heating roller is separated, the solenoids 9A and 9B are turned on and the cam 8A is moved. Further, when it is determined that the separation claw 6 is separated by both the separation claw 6A for the heating roller and the pressure roller 6B, the cam 8A and the cam 8B are moved. Then, each cam 8 moves each support shaft 7 to separate the separation claw 6A and the separation claw 6B (step # 5).

  After the separation of the separation claws 6A and 6B is completed in step # 5 and when the control unit 10 determines not to separate the separation claws 6A and 6B (No in step # 3), the control unit 10 Is not left, and it is confirmed that there is no sheet to pass through the fixing device 1 (step # 6). If there is still a sheet to pass (No in step # 6), for example, the process returns to step # 2. On the other hand, if there is no sheet to pass (Yes in Step # 6), for example, the control unit 10 turns off the solenoids 9A to 9D and retracts all the cams 8A and 8B (Step # 7). Further, the control unit 10 turns off the fixing motor 16, the rotation of the heating roller 4 and the pressure roller 5 is stopped (step # 8), and the process ends (end).

(Second Embodiment)
Next, a second embodiment of the present invention will be described based on FIG. FIG. 9 is a schematic plan view of the fixing device 1 according to the second embodiment as viewed from above for explaining an example of the separation mechanism 15 according to the second embodiment of the present invention.

  In the second embodiment, the separation mechanism 15 is different in that the support shafts 7A and 7B are not moved by the cam 8, but are moved (lifted) by the solenoids 9E to 9N (separation mechanism 15). The other parts in the machine 100 may be the same as those in the first embodiment, and the description of common parts is omitted, and the same reference numerals are used.

  As shown in FIG. 9, the heating roller 4 is provided with a plurality of support shafts 7A for supporting a plurality of separation claws 6A, and the pressure roller 5 is provided with a plurality of support shafts 7B for supporting a plurality of separation claws 6B. This is the same as in the first embodiment. However, in the present embodiment, three support shafts 7A for the heating roller are provided. Thus, three or more support shafts 7A and 7B may be provided for the heating roller 4 and the pressure roller 5 (also in the first embodiment). Since the pressure roller 5 of this embodiment has a smaller diameter than the heating roller 4, the number of support shafts 7B for the pressure roller is two as in the first embodiment.

  As shown in FIG. 9, the heating roller support shaft 7A is provided with three separation claws 6A (total of nine separation claws 6A for the heating roller). Thus, the support shaft 7A and the support shaft 7B may support three or more separation claws 6A (also in the first embodiment). Also in this embodiment, as in the first embodiment, each support shaft 7 (7A, 7B) has a region F1 where the rollers contact when a minimum size sheet passes and a region F2 where the rollers do not contact each other. At least one separation claw 6 is brought into contact with each roller.

  In the present embodiment, for example, pull-type solenoids 9E to 9N are provided above the ends of the support shafts 7 (7A and 7B). And the movable iron core of solenoid 9E-9N is connected with the edge part of each support shaft 7 of the downward direction. When a current is passed through a pair of solenoids 9 (for example, 9E and 9F) facing each other in the axial direction of the heating roller 4 and the pressure roller 5, the ends of the support shafts 7 to be connected are lifted, and the separation claws 6 are moved to the heating roller. 4 and the pressure roller 5. When the current supply to the solenoids 9E to 9N is stopped, the support shafts 7 return to the positions where the respective separation claws 6 to be in contact with the rollers due to their own weights, recovery springs in the respective solenoids 9 and the like (reference) Back to position).

  For example, when the single support shaft 7A is moved and the separation claw 6A is separated, the control unit 10 simultaneously turns on the two solenoids 9G and 9H connected to the single support shaft 7A. Thereby, one support shaft 7A is lifted (moved). In this way, the control unit 10 can control the timing at which the separation claw 6A and the separation claw 6B are separated by controlling the timing at which the solenoids 9E to 9N are turned on.

  For example, the control unit 10 does not move all the support shafts 7A at the same time with respect to the support shaft 7A for the heating roller. Further, the controller 10 does not move all the support shafts 7B for the pressure roller at the same time. In other words, the control unit 10 includes the support shafts 7 (7A, 7B) such that at least one separation claw 6A is in contact with the heating roller 4 and at least one separation claw 6B is in contact with the pressure roller 5. ). For example, the support shaft 7A is moved in order from the left one of the support shafts 7A for the heating roller.

  It should be noted that the timing for separating the separation claws 6 may be the same as the criteria for determination described with reference to FIG. 8 in the first embodiment. Also, the flow of separation control is not provided with each cam 8 in this embodiment, but may be basically the same as the example shown in FIG. 8 (step # 4 and step # 7 can be omitted). In addition, as described with reference to FIG. 7, the ON / OFF control of the solenoids 9E to 9N is provided with the separation mechanism control unit 151, and if the solenoids 9E to 9N are connected to the switch units that turn ON / OFF, The control unit 10 can control which solenoid 9 is to be turned on / off and the timing to be turned on / off.

  Thus, according to the invention shown in the first and second embodiments, since the separation mechanism 15 is provided, the separation claw 6 is brought into contact with the rotating body (for example, the heating roller 4 and the pressure roller 5). Can be separated from When the separation claw 6 is separated, the accumulated toner is dragged by the rotation of the rotating body and is sent, so that the toner is removed from between the rotating body and the separation claw 6. The toner that has been sent falls from, for example, a rotating body. Thereby, it is possible to prevent toner from being accumulated between the separation claw 6 and the rotating body. Accordingly, it is possible to provide the fixing device 1 in which the toner is conspicuously accumulated on the sheet, and the sheet is not contaminated by the spilled toner and the image quality is not deteriorated. Further, when separating the separation claw 6, the separation mechanism 15 keeps at least one separation claw 6 out of the plurality of separation claws 6 in contact with the rotating body. However, the paper can be separated from the rotating body. That is, even if the separation claw 6 is separated, the function of the separation claw 6 is not impaired. As a result, it is possible to prevent the occurrence of jamming and folding of the paper due to the winding of the paper.

  Further, when separating the separation claw 6, the separation mechanism 15 does not move at least one support shaft 7 of the support shafts 7 for each rotation body, so when the paper is wound around the rotation body. Even if it occurs, the sheet can be separated from the rotating body. That is, even if the separation claw 6 is separated, the function of the separation claw 6 is not impaired. Further, the plurality of separation claws 6 can be separated at a time by the movement of the support shaft 7. Further, the support shaft 7 supports at least one separation claw 6 so as to come into contact with the rotating body in a region where the minimum size paper that can pass through the fixing device 1 and the rotating body contact, and at least one separation outside the region. The nail 6 is supported. Accordingly, even when a small-size sheet is wound around the rotating body, the sheet can be reliably separated from the rotating body. Further, in the case of a large-sized sheet, the sheet is separated by two or more separation claws 6, and the sheet can be reliably separated from the rotating body.

  Further, since the separation mechanism 15 includes the cam 8 or the solenoid 9, the separation claw 6 can be separated from the rotating body with a simple configuration. Further, since the separation mechanism 15 separates the separation claw 6 every time a predetermined number of sheets pass or every time the rotating body rotates a predetermined number of times, the separation mechanism 15 periodically accumulates between the separation claw 6 and the rotating body. Toner can be removed. Moreover, when the separation claw 6 is provided, whether it is a heating rotator (heating roller 4) or a pressure rotator (pressure roller 5), between the separation claw 6 and the heating rotator, It is possible to prevent toner from accumulating between the separation claw 6 and the pressure rotating body. In addition, it is possible to provide an image forming apparatus (for example, the multifunction peripheral 100) that is free from jamming and paper folding due to paper wrapping. In addition, it is possible to provide an image forming apparatus in which the sheet is not soiled by the toner accumulated between the separation claw 6 and the rotating body and the image quality on the printed matter is high. In addition, the higher the toner concentration, the more toner adheres to each rotating body, and the toner tends to accumulate between the rotating body and the separation claw 6, but the number of pixels on which the toner is placed on the paper Is determined to exceed the predetermined value, the separation mechanism 15 separates the separation claw 6, so that toner can be efficiently prevented from accumulating between the separation claw 6 and the rotating body.

  Next, another embodiment will be described. Although the configuration in which the cams 8A and 8B are moved is shown in the first embodiment, the cams 8A and 8B may be fixedly provided without being moved. If the rotational speeds of the cams 8A and 8B are adjusted according to the number of teeth of each gear, the number of teeth of the rotating shaft 81, and the like, the separation claws 6A and 6B can be adjusted to be separated.

  In addition, an example in which the separation claw 6A, the support shaft 7A and the separation mechanism 15 are provided on the heating roller 4 and the separation claw 6B, the support shaft 7B, and the separation mechanism 15 are provided on the pressure roller 5 has been described. The separation mechanism 15 and the like may be provided only on one of the heating roller 4 and the pressure roller 5.

  In the above description, an example in which the heating roller 4 and the pressure roller 5 are provided as the rotating body in the fixing device 1 has been described. However, for example, a belt is attached to the fixing device 1 with two rollers for heating. Even when a stretched belt rotating body is provided, the separation claw 6 can be provided on the belt rotating body, and therefore the present invention can be applied.

  The embodiment of the present invention has been described above, but the scope of the present invention is not limited to this, and various modifications can be made without departing from the spirit of the invention.

  The present invention is applicable to a fixing device including a rotating body and a separation claw that contacts the rotating body, and an image forming apparatus including the fixing device.

1 Fixing device 4 Heating roller (rotating body, heating rotating body)
5 Pressure roller (rotating body, rotating body for pressure) 6 Separation claw 6A Separation claw (for heating roller) 6B Separation claw (for pressure roller)
7 Support shaft 7A Support shaft (for heating roller)
7B Support shaft (for pressure roller) 8 Cam (separation mechanism 15)
8A Cam (for heating roller) 8B Cam (for pressure roller)
9 Solenoid (separation mechanism 15) 9A, 9B Solenoid (for heating roller)
9C, 9D Solenoid (for pressure roller) 9E-9J Solenoid (for heating roller)
9K to 9N Solenoid (for pressure roller) 10 Control unit 100 Multifunction machine (image forming apparatus)

Claims (9)

A rotating body that contacts the paper on which the toner image is transferred;
A plurality of separation claws that contact the rotating body and separate paper from the rotating body;
A fixing device having a separation mechanism for separating the separation claw from a position where the separation claw comes into contact with the rotating body.   2. The fixing device according to claim 1, wherein, when the separation claw is separated, at least one of the plurality of separation claws is in contact with a rotating body. A plurality of support shafts for supporting the separation claw;
2. The separation mechanism according to claim 1, wherein the separation mechanism moves the support shaft to separate the separation claw from the rotating body, and at least one of the support shafts does not move from the position. Or the fixing device according to 2;   Each of the support shafts supports at least one of the separation claws so as to be in contact with the rotating body in a region where the rotating body is in contact with the minimum size paper that can pass through the fixing device, and at least one outside the region. The fixing device according to claim 3, wherein the two separation claws are supported.   The fixing device according to claim 1, wherein the separation mechanism includes a cam and / or a solenoid.   6. The separation mechanism according to claim 1, wherein the separation mechanism separates the separation claw every time a predetermined number of sheets pass or every time the rotating body rotates a predetermined number of times. Fixing device. The rotator is heated by a heating element and is heated by a heating rotator that heats a sheet on which a toner image is transferred, and a pressing rotator that is in contact with the heating rotator and forms a nip. Yes,
When the rotator is both the heating rotator and the pressurizing rotator, a plurality of the separation claws, the separation mechanism, and a plurality of the support shafts are provided for each rotator. The fixing device according to claim 3, wherein the fixing device is a fixing device.   An image forming apparatus comprising the fixing device according to claim 1. A control unit that counts the number of pixels on the paper based on the image data to be printed,
The image forming apparatus according to claim 8, wherein the separation mechanism separates the separation claw when the control unit determines that the number of pixels on the sheet exceeds a predetermined value.

Images