JP2011221438A - Fixing device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device comprising an external heating member to heat a surface of a fixing member, capable of cleaning the fixing member as well as the external heating member by cleaning the external heating member and preventing a cleaning member from sticking to the external heating member due to toner being solidified after melting which causes deformation of the external heating member and tearing of the cleaning member.SOLUTION: The fixing device comprises a contacting and separating mechanism enable the cleaning member to contact with and separate from the external heating member.

Description

  The present invention relates to an electrophotographic image forming apparatus, and more particularly to a fixing device that fixes a toner image.

  In an electrophotographic image forming apparatus, a fixing device that heats and fixes a toner image is used.

  There is a demand for a fixing device capable of high-speed processing in response to an increase in the speed of image forming apparatuses. Further, with the widespread use of color image forming apparatuses, a fixing apparatus suitable for fixing a color toner image is desired.

  Fixing technology that can cope with speeding up and colorization efficiently heats the fixing member that heats the toner image, and quickly supplies heat to the fixing member in response to the temperature drop of the fixing member that occurs during the fixing process. The technology to do is demanded.

  As such a fixing technique, an external heating technique for heating the surface of the fixing member has been attracting attention.

  In fixing a color toner image, since a large amount of toner forms an image, a fixing member that contacts and heats the toner image so as to wrap the toner image is used. There is what is called Laura. The soft roller is a roller in which an elastic layer is formed on a base such as metal. The conventional soft roller has a built-in heater and is heated from the inside by the built-in heater.

  The surface temperature of the fixing roller is controlled to a predetermined fixing temperature by controlling the heater to be turned off when the temperature detected by the temperature sensor exceeds the high temperature side threshold value and to be turned on when the temperature is below the low temperature side threshold value. Maintained.

  In such temperature control, in the case of a soft roller, the response speed to a temperature change is lower than that of a so-called hard roller having no elastic layer, and it becomes difficult to control the surface temperature of the fixing roller.

  An external heating member is used as a means for solving this problem. Since the external heating member heats the surface of the fixing member from the outside, the response speed of the surface temperature of the fixing member is fast, and even when a soft roller is used as the fixing member, the surface temperature of the fixing member can be maintained at an appropriate value. It becomes.

  As a fixing device using an external heating member, there is one described in Patent Document 1.

  Japanese Patent Application Laid-Open No. 2004-151858 proposes that a fixing device that heats a fixing member with an external heating member keeps the external heating member and the fixing member clean by cleaning a heating belt that is an external heating member with a cleaning unit. Yes.

JP 2009-300624 A

  In Patent Document 1, the toner that moves from the external heating member to the cleaning unit and adheres to the cleaning unit is removed by applying vibration to the cleaning unit. However, it is impossible to completely remove the toner from the cleaning means.

  The external heating member stops when the fixing device stops, but the external heating member stops when the external heating member and the cleaning unit are in contact with each other, and stops when toner is interposed between the external heating member and the cleaning unit. Will do. In this state, when the temperature is lowered by turning off the power, the toner is solidified and the external heating member and the cleaning unit are adhered, and the heating belt as the external heating member is deformed or used as a cleaning unit in the next operation. The cleaning web may be torn.

  SUMMARY OF THE INVENTION An object of the present invention is to solve the above-described problems and to provide a fixing device and an image forming apparatus that perform normal fixing over a long period of time and perform good fixing over a long period of time. To do.

  The object is achieved by the following invention.

1. A fixing member that heats and fixes the toner image to the recording material;
A pressure member that presses the recording material against the fixing member;
An external heating member that contacts the fixing member and heats the surface of the fixing member;
A cleaning member that contacts the external heating member to clean the external heating member;
In a fixing device having
A fixing device having a contact / separation mechanism for separating the cleaning member from the external heating member when the fixing device is stopped.

  2. 2. The fixing device according to 1, wherein the contact / separation mechanism separates the external heating member from the fixing member when the fixing device is stopped.

  3. 2. The fixing device according to claim 1, wherein the contact / separation mechanism separates the cleaning member from the external heating member while maintaining contact between the fixing member and the external heating member.

  4). The contact or separation mechanism performs the contact or separation between the cleaning member and the external heating member and the contact or separation between the fixing member and the external heating member at different timings. 4. The fixing device as described in 3 above.

  5. The fixing device according to any one of claims 1 to 4, wherein the external heating member is a heating belt.

  6). The fixing device according to any one of 1 to 5, wherein the cleaning member is formed of a cleaning web.

  7). 7. The fixing device according to claim 1, wherein the contact / separation mechanism separates the cleaning member from the external heating member when the power is turned off.

  8). An image forming apparatus comprising: an image forming unit that forms an image on a recording material; and the fixing device described in any one of 1 to 7 above.

  In the present invention, the cleaning member is separated from the external heating member during a pause. Therefore, sticking of the cleaning member and the external heating member that occur when the cleaning member and the external heating member are stopped is prevented.

1 is a diagram illustrating an overall configuration of a color image forming apparatus which is an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a diagram showing the configuration of the fixing device according to the first embodiment of the present invention. It is a figure which shows a contact separation mechanism. It is a figure which shows a contact separation mechanism. It is a figure which shows a contact separation mechanism. It is a figure which shows the fixing device which concerns on Embodiment 2 of this invention. It is a flowchart of control in Embodiment 3 of the present invention. It is a flowchart of control in Embodiment 4 of the present invention. It is a flowchart of control in Embodiment 5 of the present invention.

Hereinafter, the present invention will be described based on an image forming apparatus according to an embodiment of the present invention, but the present invention is not limited to the embodiment.
<Image forming apparatus>
FIG. 1 is a diagram showing an overall configuration of a color image forming apparatus which is an image forming apparatus according to an embodiment of the present invention.

  The image forming apparatus is called a tandem color image forming apparatus, and includes an image forming unit A and a fixing device 9 each having a plurality of sets of image forming units 10Y, 10M, 10C, and 10K and an intermediate transfer body unit 7. The image forming apparatus further includes an automatic document feeder DF and a document image reading device SC on the top thereof.

  An image forming unit 10Y for forming a yellow image includes a drum-shaped photoreceptor 1Y, a charging device 2Y, an exposure device 3Y, a developing device 4Y, and a primary transfer roller as a primary transfer device disposed around the photoreceptor 1Y. 5Y and a cleaning device 6Y. The image forming unit 10M that forms a magenta image includes a drum-shaped photoreceptor 1M, a charging device 2M, an exposure device 3M, a developing device 4M, and a primary transfer roller as a primary transfer device disposed around the photoreceptor 1M. 5M and a cleaning device 6M. An image forming unit 10C for forming a cyan image includes a drum-shaped photoreceptor 1C, a charging device 2C, an exposure device 3C, a developing device 4C, and a primary transfer roller as a primary transfer device disposed around the photoreceptor 1C. 5C and a cleaning device 6C. An image forming unit 10K that forms a black image includes a drum-shaped photoreceptor 1K, a charging device 2K, an exposure device 3K, a developing device 4K, and a primary transfer roller 5K as a primary transfer device disposed around the photoreceptor 1K. And a cleaning device 6K.

  The intermediate transfer body unit 7 includes an intermediate transfer body 70 as a semiconductive endless belt-like image carrier that is wound around a plurality of rollers 71 to 74 and is rotatably supported.

  The toner images of the respective colors formed by the image forming units 10Y, 10M, 10C, and 10K are sequentially transferred onto the intermediate transfer body 70 by the primary transfer rollers 5Y, 5M, 5C, and 5K, and the combined color toner images are obtained. It is formed. The recording material P accommodated in the paper feed cassette 20 is fed by the paper feed / conveyance device 21, passes through a conveyance unit having a plurality of intermediate rollers 22 </ b> A, 22 </ b> B, 22 </ b> C, 22 </ b> D, and a registration roller 23. Supplied to the transfer position. At the secondary transfer position, the color toner images are collectively transferred onto the recording material P by a transfer voltage applied to a roller 74 as a backup roller by a transfer power source (not shown). The recording material P to which the color toner image has been transferred is fixed by a fixing device 9 having a heat roller constant and a pressure roller, and is sandwiched between paper discharge rollers 26 and placed on a paper discharge tray 27 outside the apparatus. The

  On the other hand, after transferring the color toner image to the recording material P, the intermediate transfer body 70 obtained by separating the curvature of the recording material P is cleaned by the cleaning device 6A.

  Reference numeral 28 denotes a back surface paper feeding unit. In the double-sided image formation, an image is formed on the first surface, and the recording material P that has passed through the fixing device 9 is conveyed to the back surface paper feeding unit 28, and It is conveyed to the registration roller 23.

  During the image forming process, the primary transfer roller 5K is always in pressure contact with the photoreceptor 1K. The other primary transfer rollers 5Y, 5M, and 5C are in pressure contact with the corresponding photoreceptors 1Y, 1M, and 1C, respectively, only during color image formation.

Further, the housing 8 can be pulled out from the image forming apparatus A through the support rails 82L and 82R. The housing 8 includes image forming units 10Y, 10M, 10C, and 10K and an intermediate transfer body unit 7, and the image forming units 10Y, 10M, 10C, and 10K, and the intermediate transfer body are operated by pulling out the housing 8. The unit 7 is integrally pulled out from the image forming apparatus A.
<Fixing device>
(Embodiment 1)
FIG. 2 is a diagram showing the configuration of the fixing device according to the first embodiment of the present invention.

  The fixing device 9 includes a fixing roller 91 as a fixing member, a pressure belt 92 as a pressure member, a heater 97 as a main heater, a heating belt 100 as an external heating member, a heater 99 as a sub heater, and fixing. It has a temperature sensor SE1 for detecting the surface temperature of the roller 91, a temperature sensor SE2 for detecting the temperature of the heating belt 100, and a cleaning web 106 as a cleaning member for cleaning the external heating member.

  The fixing roller 91 has an elastic layer made of silicon rubber on a base made of a metal pipe, and a release property made of a fluororesin such as PFA (perfluoroalkyl vinyl ether) or PTFE (polytetrafluoroethylene) on the elastic layer. Each roller is formed with a surface layer. The pressure belt 92 is a belt in which a release surface layer such as PA or PTFE is formed on a base of a heat-resistant belt such as polyimide (PI). The pressure belt 92 is stretched between support rollers 93, 94, 96 and a tension roller 95, and is pressed against the fixing roller 91 between the support roller 93 on the recording material entry side and the support roller 94 on the recording material discharge side. Thus, the fixing nip NP is formed. The heaters 97 and 99 are halogen lamps. The heating belt 100 is made of metal such as tin or PI. The fixing roller 91 is heated by the heater 97 and the heating belt 100.

  As shown in the figure, the heating belt 100 contacts the fixing roller 91 and is stretched between the heating roller 98 and the support roller 101. The heating roller 98 is heated by the heater 99, the heating belt 100 is heated by the heating roller 98, and the fixing roller 91 is heated by the heating belt 100.

  The cleaning web 106 contacts the heating belt 100. The cleaning web 106 is stretched around the pressing roller 107, the winding shaft 108, and the main winding shaft 109, and is wound around the winding shaft 108 so that the portion soiled with toner is updated by cleaning. The pressure roller 107 is a sponge roller, and presses the cleaning web 106 against the heating belt 100.

  The cleaning web 106 is cleaned by rubbing the heating belt 100. The surface of the fixing roller 91 is cleaned by the cleaned heating belt 100. The take-up shaft 108 is rotated by driving a motor (not shown). For example, every time a predetermined number of images are formed, the portion that is in contact with the heating belt 100 of the cleaning web 106 is rotated to be updated with an unused portion. .

  During the image forming process, that is, during the operation of the fixing device 9, the fixing roller 91 and the heating belt 100 are in contact with each other, and the heating belt 100 and the cleaning web 106 are in contact with each other. During the operation of the fixing device 9, the fixing roller 91 rotates in a clockwise direction indicated by an arrow by driving a motor (not shown). The pressure belt 92 and the heating belt 100 are driven by the fixing roller 91.

  The recording material P is guided by the entrance guides 110A and 110B and introduced into the fixing nip NP, passes through the fixing nip NP, is conveyed by the paper discharge rollers 103A and 103B, and is discharged from the fixing device 9. The recording material P is heated by the fixing roller 91 in the fixing nip NP, and the toner image T is fixed to the recording material P. In the fixing process, heat is removed from the fixing roller 91 by the recording material P. As a result, the temperature of the surface of the fixing roller 91 tends to decrease. However, the temperature of the fixing roller 91 is decreased by heating the fixing roller 91 from the surface of the fixing roller 91 by the heating belt 100 in addition to the internal heating by the heater 97. Is avoided and good fixing is performed.

  When the fixing device 9 is not operating, the fixing roller 91 and the heating belt 100 are separated from each other, and the heating belt 100 and the cleaning web 106 are separated from each other. In the resting state, the rotation of the fixing roller 91 is stopped and the cleaning web 106 is separated from the heating belt 100. On the other hand, the heating roller 98 is rotated by driving of a motor (not shown) when the fixing device 9 is stopped to rotate the heating belt 100. Therefore, at the time of rest, the heating belt 100 is heated uniformly by the heating roller 98 over the entire length of the belt.

  Here, the rest of the fixing device 9 means a time other than when the image forming process is being executed.

  Therefore, when the image forming apparatus is turned off, when the image forming apparatus is turned off, when the copy button is operated or when an image forming instruction is received from the outside, the image forming process can be started, and when a power source other than the power source of the control unit CPU is used. Includes shut-off time when turned off.

  As described above, the fixing roller 91 and the heating belt 100 are in contact with and separated from each other, and the heating belt 100 and the cleaning web 106 are in contact with and separated from each other. Next, a contact / separation mechanism that performs such an operation will be described. Note that the fixing roller 91 may rotate in a resting state of the fixing device.

  3 to 5 show the contact / separation mechanism. 3 shows a state in which the heating belt 100 is in contact with the fixing roller 91 and the cleaning web 106 is in contact with the heating belt 100. FIG. 4 shows a state in which the heating belt 100 is separated from the fixing roller 91, and the cleaning web 106 is in the heating belt. FIG. 5 shows a state where the heating belt 100 is separated from the fixing roller 91 and the cleaning web 106 is separated from the heating belt 100. FIG. 3 shows the state of the contact / separation mechanism during operation of the fixing device 9, that is, during execution of the image forming process, and FIG. 4 shows the state during the transition process in which the fixing device 9 shifts from the operating state to the resting state. FIG. 5 shows a state when the fixing device 9 is at rest.

  The resting state of the fixing device 9 is a state at a time other than the image forming process. The fixing is performed when the image forming apparatus is on standby, when the image forming apparatus is turned off, when the image forming apparatus is stopped due to a jam, or the like. The state of the device.

  The lever 120 is rotatably supported on the shaft 120 </ b> A and is biased to rotate counterclockwise by a spring 122. The lever 123 is rotatably supported on the shaft 123A, and the lever 124 is rotatably supported on the shaft 124A.

  The lever 120 is provided with a pin 120B, and the pin 120B is in pressure contact with a cam 121 driven to rotate by a motor MT by a bias of a spring 122. The protrusion 120 </ b> C provided on the lever 120 acts on the bent portion 123 </ b> B provided on the lever 123. The pin 123 </ b> C provided on the lever 123 acts on the bending portion 124 </ b> B provided on the lever 124. A pressing roller 107 that presses the cleaning web 106 against the heating belt 100 is rotatably supported at the lower end of the lever 124.

  In FIG. 3, the heating roller 98 presses the heating belt 100 against the fixing roller 91, and the heating belt 100 is in contact with the fixing roller 91. Further, the pressing roller 107 brings the cleaning web 106 into contact with the heating belt 100. In FIG. 3, the bent portion 124B is separated from the pin 123C.

  When the motor MT is operated, the contact / separation mechanism is changed from the state of FIG. 3 to the state of FIG. 4 and further from the state of FIG. 4 to the state of FIG.

  First, by driving the motor MT, the cam 121 pushes up the pin 120B and rotates the lever 120 clockwise. Due to the rotation of the lever 120, the heating roller 98 and the support 101 are separated from the fixing roller 91, and the heating belt 100 is separated from the fixing roller 91. In addition, the protrusion 120C pushes up the bent portion 123B and rotates the lever 123 counterclockwise. However, the lever 124 does not rotate until the pin 123C contacts the bent portion 124. That is, in FIG. 4, the pressing roller 107 brings the cleaning web 106 into contact with the heating belt 100.

  When the cam 121 further rotates from the state shown in FIG. 4 to the state shown in FIG. 5, the protrusion 120C pushes up the bent portion 123B and rotates the lever 123 counterclockwise. By this rotation, the pin 123C pushes the bent portion 124B, and the lever 124 rotates in the clockwise direction. The rotation of the lever 124 moves the pressing roller 107 to the left, and the cleaning web 106 is separated from the heating belt 100.

  As described above, in the present exemplary embodiment, when the heating belt 100 contacts the fixing roller 91 and the cleaning web 106 contacts the heating belt 100, the fixing roller 91 is first switched from the operating state to the resting state. From the heating belt 100, and then the cleaning web 106 is separated from the heating belt 100.

  In the fixing process, the fixing roller 91 and the heating belt 100 are in contact with each other, and the temperature of the heating belt 100 is maintained several degrees to several tens of degrees higher than the temperature of the fixing roller 91. In the rest state, the fixing roller 91 and the heating belt 100 are separated from each other, and the temperature of the heating belt 100 is maintained several degrees to several tens of degrees higher than the temperature of the fixing roller 91.

  Since the heating belt 100 and the cleaning web 106 are separated in a rest state including when the power is turned off, the temperature of the heating belt 100 is lowered when the power is turned off. Sticking is prevented.

  When the fixing device 9 in the resting state shifts to the operating state, the reverse operation is performed from the state of FIG. 5 to the state of FIG. 3 through the state of FIG. 4, the cleaning web 106 contacts the heating belt 100, and In addition, the heating belt 100 contacts the fixing roller 91.

  As shown in FIGS. 3 to 5 and described above, when the fixing device 9 is stopped, the cleaning web 106 is separated from the heating belt 100 and the heating belt 100 is separated from the fixing roller 91.

  In the fixing process, by passing the recording material P through the fixing device, the heat of the fixing roller 91 is absorbed by the recording material P. However, by supplying heat from the heating belt 100, the fixing roller 91 is predetermined. The fixing temperature is maintained. In such temperature control, the temperature of the heating belt 100 is set higher than the temperature of the fixing roller 91.

As described above, the temperature control of maintaining the temperature of the heating belt 100 higher than the temperature of the fixing roller 91 is stably performed by separating the heating belt 100 from the fixing roller 91 during the pause.
(Embodiment 2)
FIG. 6 is a diagram showing a fixing device according to Embodiment 2 of the present invention. In the embodiment shown in FIG. 5, the contact / separation between the fixing roller 91 and the heating roller 98 and the contact / separation between the heating roller 98 and the cleaning roller 132 are composed of two drive sources DR1 and DR3. This is performed by a contact separation mechanism. The driving sources DR1 and DR2 are composed of motors, and the two motors are individually controlled to contact and separate the fixing roller 91 and the heating roller 98, and between the heating roller 98 and the cleaning roller 132. Separation is performed at different timings, the heating roller 98 and the cleaning roller 132 are separated while the contact state between the fixing roller 91 and the heating roller 98 is maintained, and various contact / separation operations are performed as necessary. It becomes possible.

  In FIG. 6, 91 is a fixing roller as a fixing member for fixing a toner image, 130 is a pressure roller as a pressure member that presses the recording material against the fixing roller 91, 97 is a heater as a main heater, and 98 is a fixing roller. A heating roller as an external heating member for heating the surface of 91, a heater as a sub-heater for heating the heating roller 98, and a cleaning roller as a cleaning member for cleaning the heating roller 98. The heating roller 98 constitutes an external heating member that heats the fixing member from the outside. Parts that are the same as the parts in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  The pressure roller 130 is a roller in which an elastic layer made of silicon rubber is formed on a base made of a metal pipe, and a releasable surface layer made of a fluororesin such as PFA or PTFE is formed on the elastic layer. The cleaning roller 132 is made of sponge, and when the contaminants collected on the cleaning roller 132 are accumulated, the cleaning roller 132 is rotated by driving a motor (not shown), and an unused portion comes into contact with the heating roller 98. It is also possible to provide a scraping member that scrapes off contaminants from the cleaning roller 132.

  In FIG. 6A, which is an operation state of the fixing device 9, the heating roller 98 contacts the fixing roller 91, and the cleaning roller 132 contacts the heating roller 98. The fixing roller 91 and the pressure roller 130 rotate as indicated by an arrow in the pressure contact state of FIG. 6A, and fix the recording material passing through the fixing nip between the fixing roller 91 and the pressure roller 130.

  The fixing device 9 is in the state shown in FIG. 6C at rest, and the fixing roller 91 and the pressure roller 130, the fixing roller 91 and the heating roller 98, and the heating roller 98 and the cleaning roller 132 are separated from each other.

  FIG. 6B shows an intermediate state in which the fixing roller 91 and the heating roller 98 are separated from each other, and the heating roller 98 and the cleaning roller 132 are in contact with each other.

  In order to set the state shown in FIGS. 6A to 6C, drive sources DR1 to DR3 for displacing the heating roller 98, the pressure roller 130, and the cleaning roller 132 are provided.

Next, an example of control of the fixing device 9 will be described. In the fixing device 9 described above, the fixing member and the external heating member are contacted and separated, and the external heating member and the cleaning member are contacted and separated. As a result, it is only possible to execute switching of contact / separation between the fixing member and the external heating member and switching of contact / separation between the external heating unit and the cleaning member at different timings. Instead, as in the embodiment described below, various operations are possible, such as switching the contact and separation between the external heating member and the cleaning member while continuing the contact between the fixing member and the external heating member. . Therefore, according to the present invention, the fixing device can be operated so as to be adapted to various operations of the image forming apparatus, and a fixing device adapted to various states and needs can be made.
(Embodiment 3)
FIG. 7 is a flowchart of control in Embodiment 3 of the present invention, which is a first example of control of the fixing device 9. “Start” in FIG. 7 is a state in which the shut-off state, which is a low energy consumption state when the main switch of the image forming apparatus is turned on or the fixing power source is turned off, is released.

  In step ST1, the heaters 97 and 99 are turned on to start warm-up. When the temperature of the fixing roller 91 detected by the temperature sensor SE1 reaches a predetermined fixing temperature and the warm-up is completed (Y in ST2), the motor MT (see FIGS. 3 to 5) is operated in step ST3 to fix the fixing. The heating belt 100 is brought into contact with the roller 91 and the cleaning web 106 is brought into contact with the heating belt 100. The operation of the contact / separation mechanism in ST3 is as described above. First, the heating belt 100 and the cleaning web 106 are in contact with each other, and then the fixing roller 91 and the heating belt 100 are in contact with each other.

  Next, printing, which is an image forming process, is performed (ST4). In printing, the surface temperature of the fixing roller 91 is maintained at a predetermined fixing temperature by turning on and off the heaters 97 and 99 based on the detected temperatures of the temperature sensors SE1 and SE2.

  When the sub-power supply is turned off during printing or at the end of printing, each unit other than the CPU is turned off (ST5). In the present embodiment, the power supply of the motor MT is held even after the sub power supply is turned off in step ST5, and is held during execution of the next step ST6.

  In step ST <b> 6, the motor MT is operated to separate the heating belt 100 from the fixing roller 91 and to separate the cleaning web 106 from the heating belt 100.

  FIG. 8 is a flowchart of control in Embodiment 4 of the present invention, which is a second example of control of fixing device 9. In the example of FIG. 8, the contact separation between the fixing roller 91 and the heating belt 100 and the contact separation between the heating belt 100 and the cleaning web 106 are executed by different driving sources (for example, DR1 and DR3 in FIG. 6). In the present exemplary embodiment, switching from contact to separation between the fixing roller 91 and the heating belt 100, switching from separation to contact, and from contact to separation between the heating belt 100 and the cleaning web 106. And switching from separation to contact are executed separately.

  In step ST10, the fixing device 9 is brought into an operable state, such as maintaining the fixing roller 91 at a predetermined fixing temperature and maintaining the heating belt 100 at a predetermined temperature. Note that immediately before step ST10, the heating belt 100 is in contact with the fixing roller 91, the cleaning web 106 is separated from the heating belt 100, and the temperature of the fixing roller 91 is the fixing temperature. That is, the start stage of the flow in FIG. 8 is a state in which the fixing device is in a standby state.

  When there is a print start command, that is, a copy button operation or a print command from an external device (Y in ST11), the cleaning web 106 contacts the heating belt 100 in step ST12.

  After the cleaning web 106 comes into contact, printing is executed in step ST13.

  When printing is finished (Y in ST14), the cleaning web 106 is separated from the heating belt 100 and finished in step ST15.

  FIG. 9 is a flowchart of control in Embodiment 5 of the present invention, which is a third example of control of the fixing device 9. In the example of FIG. 9, the contact separation between the fixing roller 91 and the heating belt 100 and the contact separation between the heating belt 100 and the cleaning web 106 are performed at the same timing.

  The same steps as those in FIG. 8 are denoted by the same reference numerals, and the description thereof is omitted.

  In the present embodiment, the heating belt 100 is separated from the fixing roller 91 and the cleaning web 106 is separated from the heating belt 100 in the “start” state.

  In step ST12A, the heating belt 100 contacts the fixing roller 91, and the cleaning web 106 contacts the heating belt 100.

  In step ST15A, the heating belt 100 is separated from the fixing roller 91, and the cleaning web 106 is separated from the heating belt 100.

9 Fixing device 91 Fixing roller 92 Pressure belt 97, 99 Heater 100 Heating belt 106 Cleaning web 98, Heating roller 132 Cleaning roller

Claims (8)

A fixing member that heats and fixes the toner image to the recording material;
A pressure member that presses the recording material against the fixing member;
An external heating member that contacts the fixing member and heats the surface of the fixing member;
A cleaning member that contacts the external heating member to clean the external heating member;
In a fixing device having
A fixing device having a contact / separation mechanism for separating the cleaning member from the external heating member when the fixing device is stopped.   The fixing device according to claim 1, wherein the contact / separation mechanism separates the external heating member from the fixing member when the fixing device is stopped.   The fixing device according to claim 1, wherein the contact / separation mechanism separates the cleaning member from the external heating member while maintaining contact between the fixing member and the external heating member.   3. The contact / separation mechanism executes contact / separation between the cleaning member and the external heating member and contact / separation between the fixing member and the external heating member at different timings. Alternatively, the fixing device according to claim 3.   The fixing device according to claim 1, wherein the external heating member includes a heating belt.   The fixing device according to claim 1, wherein the cleaning member includes a cleaning web.   The fixing device according to claim 1, wherein the contact / separation mechanism separates the cleaning member from the external heating member when the power is turned off.   An image forming apparatus comprising: an image forming unit that forms an image on a recording material; and the fixing device according to claim 1.

Images