JP4774330B2 - Fixing apparatus and image forming apparatus using the same - Google Patents

Description

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

  Generally, a fixing device used in an image forming apparatus generally has a configuration having a heat source inside a fixing roller or a pressure roller. In the fixing device, the object to be heated is heated / pressurized only at the nip portion, so that the temperature around the fixing roller around the nip portion can be fixed, and the other portions are hot. There is no need. Therefore, in order to shorten the warm-up time, a method of heating a partial region in the circumferential direction of the rotating body (a portion in the circumferential direction and extending over the entire axial direction of the rotating body) is preferable. However, in the method of heating a partial region in the circumferential direction of the rotator, the temperature is often detected outside the heating region (the region heated by the heating source), so the rotator is heated in a stopped state. In this case, while the temperature detection unit raises the temperature to the fixable temperature, the heating area is heated further, which may cause problems such as heat resistance and durability of the material used for the rotating body and paper burnout. is there. In particular, when the heating source is outside the rotating body, a problem easily occurs because the time until the surface of the rotating body reaches a high temperature is short. In addition, when a film or belt is used, it is difficult to rotate at high speed due to a problem of misalignment, and it is necessary to use a heating roller for high speed correspondence.

  In the case of an image heating fixing device as a heat roller type heating device (explained as a conventional example in [Patent Document 1], for example), FIG. 18 (reference numerals are based on [Patent Document 1], and correspondence with other figures. As shown in (1), the thermal conductivity can be increased by reducing the thickness of the hollow core metal 82 of the fixing roller 80 as much as possible. However, when the transfer material P is passed because the heat capacity is reduced, However, there is a problem that the temperature fluctuation (ripple) on the surface of the fixing roller 80 increases due to the heat radiation to the transfer material P, and thus the fixing property of the toner image on the transfer material P becomes uneven. Furthermore, it is difficult to make the hollow metal core 82 a thin metal having a wall thickness of 1 mm or less due to mechanical strength and manufacturing limitations. For this reason, in the heat roller type image heating and fixing apparatus using the fixing roller 80 and the pressure roller 90, it has not been easily achieved to reduce the warm-up time required recently. Therefore, even when the image forming apparatus is not in operation, the surface of the fixing roller 80 needs to be heated to some extent, and power consumption is large.

  In recent years, fixing methods aiming at energy saving have become widespread, and a fixing method in which heating is performed from the outside has been proposed in order to shorten the startup time. Examples of this type of fixing device that heats from the outside include those disclosed in [Patent Document 1], [Patent Document 2], and [Patent Document 3].

  The features of the configuration described in [Patent Document 1] will be described with reference to FIG. 19 (reference numerals are based on Patent Document 1 and have no corresponding relationship with other drawings). A heating means 15 for heating from the outside is provided, and the heating rotator 10 includes an elastic layer 12 inside, and a metal sleeve 13 having a thickness of 10 to 150 μm is provided on the outside, and the heating rotator and the heating member are heated. In order to make the nip formed with the pressure member substantially flat, the surface hardness of the pressure member is set to be substantially equal to or higher than the surface hardness of the heating rotor, and the heating means is radiant heating means or contact. It is supposed to be direct heating means by means of, or induction heating means by forming an alternating magnetic field.

  The features of the configuration described in [Patent Document 2] will be described with reference to FIG. 20 (reference numerals are based on [Patent Document 2] and there is no corresponding relationship with other drawings). And a pressure roller 30 in pressure contact therewith, and a heating source 32 for heating a partial region in the circumferential direction of the fixing roller 28 is provided outside the fixing roller 28. The temperature of the fixing roller 28 is detected by the thermistor 34. During the warm-up of the fixing roller 28 until the temperature reaches a preset temperature, the fixing roller 28 is rotated.

  Further, in the disclosed technique of [Patent Document 3], for example, as shown in FIG. 21 (reference is based on [Patent Document 3]), a transfer fixing member to which an image on the intermediate transfer body 2 is transferred, and the transfer The image forming apparatus includes a heating unit that heats the image on the fixing member, and a pressure roller that forms a nip with the transfer fixing member, and has a configuration for fixing the image on the paper P that passes through the nip. The image forming apparatus includes an internal heating unit built in the transfer fixing member and an external heating unit that heats the image on the transfer fixing member from the surface side. Thereby, fixing efficiency and image quality can be improved while preventing overheating of the intermediate transfer member when the intermediate transfer member is used.

  The same [Patent Document 3] discloses various configurations including external heating means such as the configurations shown in FIGS. 22, 23, 24, and 25 in addition to the above configuration. Incidentally, in [Patent Document 3], the external heating means is fixedly arranged in any configuration.

  In addition to this, there is known one that appropriately controls heating in the fixing unit using an external heating means. For example, [Patent Document 4] proposes a fixing device in which the temperature of the fixing means can be quickly switched to a set temperature. In this fixing device, the heating mode of the fixing roller for fixing the medium (paper) P carrying the developer image is set to a first heating mode and a second temperature higher than the first heating mode depending on the type of the medium P. Control means for changing to the heating mode, and an auxiliary heating roller for heating the fixing roller from the outside.

  By the way, [Patent Document 1] and [Patent Document 2] describe radiation heating and induction heating as heating means. At this time, there is no description on how to deal with the case where the winding around the heating roller or the transfer paper jam occurs at the nip portion. In particular, when the heating means is a heat source, if the transfer paper is exposed to the nip for a long time, it may cause a problem such as ignition, which is very dangerous.

  Even in the normal internal heating and fixing method, there is a method to cope with the jam of the transfer paper, but in the fixing method that is heated from the outside, in consideration of the presence of the transfer paper near the heat source, the transfer is more than ever. It is necessary to consider a countermeasure so that there is no abnormal heating of the paper.

  For example, [Patent Document 5] Japanese Patent Application Laid-Open No. 2000-30851 also discloses a heating device (fixing device) provided with a radiant heat source for heating the paper conveyance path from the outside. In the disclosed technology, in the heating device that has an external heating source that heats the heating body from the outside, passes the material to be heated while contacting the heating body, and applies thermal energy, the external heating source is A movable means that can be retracted from the heating body is provided so that the heating source can be pulled out.

  [Patent Document 6] also discloses a radiation type fixing device provided with a radiant heat source for heating the paper conveyance path from the outside. This radiation type fixing device is provided with a shutter mechanism in order to prevent overheating and ignition of the recording paper when an abnormality such as a jam occurs, and the shutter rotates to cut off between the radiant heat source and the conveyance path.

  In the above [Patent Document 6], a solenoid is used as an actuator for rotating the shutter. However, as an actuator capable of high speed operation and used in a fixing device, for example, see [Patent Document 7]. As disclosed, an electrostatic actuator that controls the deformation shape of an elastic movable body by an electrostatic attractive force that works by applying a voltage between electrodes and a mechanical restoring force of the elastic movable body, [Patent Document 8] As disclosed in the above, the electrode layer, the non-volatile ion-electrolyte-containing housing layer in contact with the electrode layer, and a conductive polymer layer are provided in a laminated state, and a potential difference is generated between the conductive polymer layer and the conductive polymer layer. The conductive polymer layer expands by application of a voltage to cause the expansion and deforms at least in the longitudinal direction, which is a direction orthogonal to the thickness direction, while the conductive polymer layer By applying a voltage to generate a potential difference the conductive polymer layer is contracted, there is at least an actuator or the like so as to shrinkage deformation in the longitudinal direction is a direction perpendicular to the thickness direction.

In addition, an electrostatic actuator as disclosed in [Patent Document 9] or an annular body made of a shape memory alloy formed in an annular shape as in [Patent Document 10] is substantially C-shaped along its circumferential direction. There is also known an actuator or the like in which an actuator part is formed by providing a shaped elastic body, and the diameter of the actuator part is changed by applying a voltage to the annular body to generate heat.
In general, it is preferable to optimize the toner shape in order to achieve high image quality in image fixing. [Patent Document 11] describes that toner having a Wadel practical sphericity φ of 0.8 or more has improved transferability.

Japanese Patent Laid-Open No. 08-129313 JP 2002-43026 A JP 2004-145260 A Japanese Patent Laid-Open No. 11-15326 Japanese Unexamined Patent Publication No. 2000-30851 JP-A-62-38490 JP 2005-245151 A JP 2005-51949 A JP-A-11-277742 JP 2005-46323 A JP 9-258474 A

  As described above, in the external heating type fixing device section, a technology for preventing the danger of heating and ignition due to the transfer paper being exposed to the nip portion for a long time in response to a jam or the like of the transfer paper is known. However, the actuator requires electric power for this prevention operation. Further, in the event of an emergency in which power is not supplied (such as a forced power-off of the main body due to a power failure or disconnection of a power outlet), power is not supplied instantaneously, and thus there is a problem that a desired danger cannot be prevented. By the way, there is a method to deal with the normal configuration by providing a backup power supply as an emergency in the main body, but it is a problem that the cost increases.

  Therefore, in the present invention, the heating action (heat source supply) in the heat source supply unit in the fixing method in which heating is performed from the outside is instantly interrupted by a simple and low-cost configuration that is excellent in power saving, thereby causing dangers such as ignition. Further, the fixing device and the image forming apparatus that prevent the above-described problem can be ignited by heating the recording medium by moving the heating unit side away from the normal position even in an emergency when the power is not supplied. It is an object of the present invention to provide a fixing device and an image forming apparatus that can reliably prevent danger and ensure safety.

  The fixing device of the present invention is a fixing device that forms a nip by a heating member and a pressure member, and presses and fixes an image on a recording medium passing through the nip, and a heating unit that heats the heating member from the outside. And a movable means for moving the heating means by a sheet-like member that deforms depending on the presence or absence of energization, the movable means corresponding to the presence or absence of energization at a position where the heating means is not positioned to heat the heating member. It is characterized in that the heat source supply can be stopped by moving to a position in which it can be moved or not heated. As a result, when the machine (fixing device or image forming apparatus including the same) is abnormally stopped (for example, a recording medium wound around the heating unit or jammed at the nip), the heat source is supplied to the heating unit. By turning OFF and instantaneously moving the heating means side, the heating is immediately stopped, the danger that the recording medium is heated and ignited can be prevented, and safety can be ensured. In particular, since a sheet-like member that is deformed depending on whether or not energization is used for the movable means, a simple and low-cost configuration can be achieved and power saving can be achieved. If regular heating is performed while the sheet-like member is energized, the heat source supply to the heating means is reliably turned off to ensure safety even when the power is cut off at the time of abnormality.

Further, in the fixing device of the present invention, may be made to the movable heating means with sheet Yatta.

  In the present invention, the image forming apparatus is configured by using any one of the transfer and fixing apparatuses as described above. In the fixing unit of the image forming apparatus, the same operation and effect as described above can be obtained. That is, when the fixing unit of the image forming apparatus abnormally stops due to, for example, a recording medium winding around the heating unit or a jam at the nip, heating is performed by instantaneously moving the heating unit side away from the normal position. It is possible to stop immediately, prevent a danger that the recording medium is heated and ignite, and secure safety. Further, in this image forming apparatus, it is preferable to use a toner having a Wadel practical sphericity φ of 0.8 or more as a developer, and a toner having a Wadel practical sphericity φ of 0.8 or more is a transfer property. Therefore, it is possible to improve the image quality by using this.

  According to the present invention, even when the fixing device or an image forming apparatus including the fixing device abnormally stops (for example, due to a recording medium wound around the heating unit or a jam in the nip unit), Can be moved away from the normal position to immediately stop heating by the heating means, prevent the danger of the recording medium being heated and ignited, ensuring safety, especially excellent in power saving and easy In addition, it can be realized with a low-cost configuration.

[First Embodiment]
Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic sectional side view showing a main part of a first embodiment of a tandem type color copying machine as an image forming apparatus according to the present invention. Based on FIG. 1, the configuration and operation outline of the apparatus of this embodiment will be described. This color copying machine includes an image forming unit 1A located at the center of the apparatus main body, a paper feeding unit 1B located below the image forming unit 1A, and an image reading unit (not shown) located above the image forming unit 1A. Have.

  An intermediate transfer belt 2 serving as an intermediate transfer member having a transfer surface extending in the horizontal direction is disposed in the image forming unit 1A, and the upper surface of the intermediate transfer belt 2 has a color complementary to the color separation color. A configuration for forming an image is provided. That is, the photoreceptors 3Y, 3M, 3C, and 3B as image carriers capable of carrying an image of toners of complementary colors (yellow, magenta, cyan, and black) are juxtaposed along the transfer surface of the intermediate transfer belt 2. Has been.

  Each of the photoreceptors 3Y, 3M, 3C, and 3B is configured by a drum that can rotate in the same direction (counterclockwise direction). A writing device 5, a developing device 6, a primary transfer device 7, and a cleaning device 8 are arranged as writing means. The alphabets attached to the respective symbols correspond to the colors of the toner as in the photosensitive member 3. Each developing device 6 accommodates each color toner. The intermediate transfer belt 2 is configured to be wound around the opposing roller 9 (driving roller), the tension roller 51, and the driven roller 10 and move in the same direction at the facing position of the photoreceptors 3Y, 3M, 3C, 3B. is doing. A cleaning device 11 that cleans the surface of the intermediate transfer belt 2 is provided at a position facing the driven roller 10. Here, the driving roller is set to the opposing roller 9, but the driving roller is not limited to the opposing roller 9, and may be provided on the upstream side or the downstream side of the opposing roller 9.

  The surface of the photoreceptor 3Y is uniformly charged by the charging device 4, and an electrostatic latent image is formed on the photoreceptor 3Y based on image information from the image reading unit. The electrostatic latent image is visualized as a toner image by a developing device 6Y containing yellow toner, and the toner image is primary-transferred onto the intermediate transfer belt 2 by a primary transfer device 7Y to which a predetermined bias is applied. Transcribed. The other photoconductors 3M, 3C, and 3B form similar images only with different toner colors, and the toner images of the respective colors are sequentially transferred onto the intermediate transfer belt 2 and superimposed. The toner remaining on the photoreceptor 3 after the transfer is removed by the cleaning device 8, and the potential of the photoreceptor 3 is initialized by a neutralizing lamp (not shown) after the transfer to prepare for the next image forming process.

  The paper feed unit 1B has a paper feed tray 16 for stacking and storing paper P as a recording medium, and a paper feed roller 17 for separating and feeding the paper P in the paper feed tray 16 one by one in order from the top. Then, after the sheet P is temporarily stopped and the oblique deviation is corrected, the registration roller pair 19 fed toward the nip N at a timing when the leading edge of the image on the transfer fixing roller 13 coincides with a predetermined position in the transport direction is changed. Have. If necessary, the configuration may be such that a pair of transport rollers for transporting the fed paper P is further provided before and after the pair of registration rollers 19.

  A fixing device 12 is provided in the lower part near the opposing roller 9. The fixing device 12 includes a pressure roller 14 that is provided to face the transfer fixing roller 13 and that is pressed by pressure means such as a spring to form a nip N. A toner image T (hereinafter also simply referred to as “toner”) primarily transferred from the photoreceptors 3Y, 3M, 3C, and 3B onto the intermediate transfer belt 2 is applied to the counter roller 9 by a secondary bias applying unit (not shown). The image is secondarily transferred to the transfer fixing roller 13 by electrostatic force by bias (including superposition of AC, pulse, etc.). An adhesive transfer method by heating toner that is not electrostatic force or a method of transferring using both electrostatic force and adhesive may be used.

  The transfer fixing roller 13 and the pressure roller 14 are made of a metal pipe-shaped metal core 53 such as aluminum, an elastic layer of about 0.05 to 0.5 mm on the surface thereof, and PFA or PTFE, which is a fluorine resin material of 10 to 30 μm. The release layer is composed of a coating or a tube. Depending on the configuration, there may be only one of the rollers. Further, a halogen heater 15 is provided as a heating means for heating the toner image on the roller surface layer of the transfer fixing roller 13. Since it is necessary to hold an image for the length of the paper, the outer diameter of the transfer and fixing roller 13 is equal to or longer than the length of the recording medium. Further, based on the thermistors (not shown) provided in the non-image area for measuring the surface temperatures of the transfer fixing roller 13 and the second transfer fixing roller (pressure roller) 14 and the respective surface temperatures obtained by these thermistors. A temperature controller (not shown) for controlling on / off of the halogen heater 15 is provided so that the temperature can be controlled independently.

  The release layer of the transfer fixing roller 13 and the pressure roller 14 is made of a conductive fluorine-based resin material in which a conductive substance such as carbon is dispersed and connected to a cored bar, thereby transferring the transfer bias between the release layers. Can be applied, the transfer bias can be lowered, and scattering during transfer can be suppressed.

  A fixing device in which the external heating means of FIG. 1 is a radiation heating type will be described in detail with reference to FIG. FIG. 2A is an explanatory view showing the heating means in the normal state, and FIG. 2B is an explanatory view showing the movable position / posture of the heating means at the time of abnormal stop. The recording medium passes through the nip forming portion between the fixing roller 13 (also referred to as a transfer fixing roller in the transfer fixing method) as a heating unit and the pressure roller 14 as a pressing unit, and the image is fixed. In the transfer fixing method with an intermediate transfer member, the opposing roller 9 is configured to be able to contact or approach in a contact or non-contact state. As an external heating means for radiant heating, the halogen heater 15 and the reflector 32 are in the position / posture (normal position) in FIG. 2 (a) in the normal state (normal state) in which the fixing roller is normally heated. When the image forming apparatus is abnormally stopped, as shown in FIG. 2B, the fractor 32 is moved from the normal position as indicated by 32a, so that the radiant heat is not heated by the fixing roller. When there is an intermediate transfer member, it moves to a position away from the opposing roller 9 as in 32b in order to prevent temperature rise.

  In the present embodiment, the movable means that moves the heating means uses a sheet-like member that deforms depending on the presence or absence of energization, and the deformation of the sheet-like member serves as a drive source for the movable means. As such a sheet-like organic material actuator, an actuator that is easy to use that moves in the air at a low voltage has been announced. An example of a movable mechanism that moves when a sheet-like member is deformed depending on the presence or absence of energization will be described with reference to the drawings. 3A is a view of the external heating means viewed from the longitudinal direction, and FIGS. 3B and 3C are views viewed from the lateral direction. As shown in the figure, the halogen heater 15 is fixed by the fixing member 104, and the both ends of the reflector 32 are held by one end of the reflector holding member 201 to be reinforced. The reflector holding member 201 can move around the fulcrum 202 and is pulled and biased by a spring 205, and the other end abuts on the position of the stopper 204 and stops.

  In one embodiment of the illustrated movable mechanism, a small sheet-like member 210 is used as an actuator. In this embodiment, the sheet-like member has a plurality of functional layers (functional regions), for example, a quadrangular shape and the like, separated and separated on one surface in the present embodiment on the surface of a thin plastic film having a thickness of about 0.1 mm. Are arranged. The functional layer is made of an organic polymer material that expands, carbon particles, or other mixed materials. When a voltage of about several tens of volts is applied to each functional layer, the material expands and bends. Bend. When no voltage is applied, the original flat state is restored. A plurality of functional layers (functional regions) can be mass-produced by applying a specific material with a printing machine, and the cost can be reduced.

  The sheet-like member suitable for the present invention is not limited to the above. It can be made of other materials as long as it has a small sheet shape that can bend and deform with and without voltage application, provides the necessary driving force and sufficient range of movement even with low voltage driving, and has the required durability. . In addition, it is preferable if it has moderate elasticity and itself has a restoring force.

  In the movable mechanism of FIG. 3, one end of the sheet-like member 210 is fixed and the other end is a free end, so that the whole is curved when a voltage is applied, and the free end moves (moves) depending on the presence or absence of voltage. ). That is, when the sheet-like member 210 is not energized, it has a flat shape as in the position of FIG. (B), and when energized, it gradually bends in the direction of the arrow in FIG. It rises and moves to the normal position while contacting the lower end (free end) 203 of the holding member 201. The free end that has moved by applying a voltage contacts the other end of the reflector holding member 201 and rotates the reflector holding member 201 to change the position / posture of the reflector 32 and supply heat.

  If no voltage is applied, the position and orientation of the reflector 32 change correspondingly and the heat source is cut off. That is, when the apparatus is movable (when energized), the sheet-like member 210 is moved to the normal position as shown in FIG. End) 203 is pressed and the heat source is supplied, but when no voltage is applied (when no current is applied), the lower end (free end) of the reflector holding member 201 is moved by moving as shown in FIG. When the normal position is released, the spring 205 is pulled and moved, and the heat source supply is turned off.

  In this type of apparatus, generally, the power supplied to the halogen heater 15 is cut off simultaneously with the stop of the machine, and the halogen heater 15 is also turned off. That is, since the contact type SW (not shown) and the contact terminal provided on the reflector holding member 201 are separated, the power supply is turned off. Thus, in this embodiment, further safety is enhanced by performing both power supply OFF control and heat source supply OFF control. Further, after returning from the stop of the machine, the reflector is returned to the normal position by energizing the sheet-like member 210 by the operation reverse to the above description.

  In this embodiment, the halogen heater 15 is used as a heating unit outside the transfer fixing roller 13, but a halogen heater 15 may be further provided inside the transfer fixing roller 13 and the pressure roller 14. Absent.

  The operation of the fixing device in the image forming apparatus of the present embodiment will be described based on the enlarged configuration diagram of FIG. 4 and the flowchart shown in FIG. The normal operation (normal operation) of the image forming apparatus will be described. As shown in the enlarged view of the fixing apparatus in FIG. 4, the sheet-like member 210 is energized and the halogen heater 15 of the external heating means is operated by the apparatus operation start operation. Is energized to start warm-up (residual heat operation) (step; S01). At this time, as shown in FIG. 4, the reflector 32 is configured to condense the radiation energy emitted from the halogen heater 15 toward the transfer fixing roller 13. When the warm-up is completed, the standby state is set (S02). During an image forming operation according to a predetermined operation (S03), the toner image placed on the intermediate transfer belt 2 is in contact with the opposing roller 9 and the transfer fixing roller 13 in a normal state (step; S04: No), or a minute gap. In this state, the toner image is transferred from the intermediate transfer belt 2 to the transfer fixing roller 13. The toner image on the transfer / fixing roller 13 is heated to a semi-molten state by condensing the radiant energy generated by the halogen heater 15 on the transfer / fixing roller 13 by the reflector 32. The surface temperature of the transfer and fixing roller 13 is controlled to a predetermined temperature by the halogen heater 15 provided in the reflector 32 from when the power of the machine body is turned on until the copying process is started. The surface temperature of the transfer fixing roller 13 is adjusted to 100 ° C. or less, preferably about 80 ° C. or less so as not to apply an excessive temperature load to the intermediate transfer belt 2. Immediately after the toner image has passed through the copying area of the reflector 32 and the halogen heater 15 after entering the copying process, the temperature distribution in the toner layer is directed to the halogen heater 15 side rather than the side in contact with the fixing roller 13. That is, the side that contacts the recording sheet is higher. Specifically, the portion in contact with the fixing roller 13 is about 80 ° C. as described above, whereas the portion facing the halogen heater 15 has sufficient fixing strength for the recording sheet. The temperature obtained is necessary. According to our study, it is known that the contact interface temperature between the toner image and the recording sheet necessary for obtaining sufficient fixing strength is about 110 to 120 ° C. In addition, since the temperature suddenly decreases at the moment when toner particles having a much smaller heat capacity than the recording sheet come into contact with the recording sheet, the toner temperature at the fixing nip inlet is required to complete the fixing process at the fixing nip outlet. It is obvious that the temperature or power is controlled so that the contact interface temperature between the toner image and the recording sheet is about 110 to 120 ° C. at the fixing nip exit. After the end of image formation (S05), the (next) image formation operation continues (S03) or returns to the standby state (S02).

  Control during abnormal operation will be described with reference to the same flowchart of FIG. When an abnormal operation (recording medium jam, non-feeding and other stop-requiring operations) is detected during the image forming operation or the like (step; S04: Yes), the external heating heat source OFF operation (S06), (intermediate transfer member) If there is, the external heating means is moved (after separation of the intermediate transfer member) (S07; the reflector is moved according to the OFF operation of the connection SW, and the heat source is cut off). Thereafter, a predetermined abnormality (recovery) treatment is performed (S08). If the abnormality detection signal is not detected again (by eliminating the abnormal state) (S09: Yes), the energization to the sheet-like member 210 is stopped. The movable part returns to a normal position (S10), and returns to normal operation after warm-up (S01) (S02: standby).

  In particular, in the present invention, the power supply to the sheet-like member 210 is stopped even when the intended control is not performed in an emergency in which power is not supplied due to a power failure or forced power OFF due to a power outlet being disconnected, etc. Therefore, the above-described S07 is also executed, the reflector is moved, the heat source is shut off, and danger is prevented. The OFF operation (S06) of the external heating heat source is naturally also passively executed.

  Note that the present invention is not limited to this embodiment, and the same can be said in the following description. When there is an intermediate transfer member, the fixing unit stops when the machine stops abnormally (assuming that power is supplied). In addition, the intermediate belt may be rotated without being stopped by separating the intermediate transfer member side. This is because the rotation is effective in suppressing the temperature rise to the belt. However, when there is a concern that the recording medium may be wound around the intermediate transfer member, it is necessary to have a configuration in which both the fixing unit and the intermediate belt are stopped from rotating. The cleaning member 61 in the embodiment does not affect the effects of the present invention, and is not limited to the configuration exemplified in the present embodiment. In some cases, the pressure roller 14 may be provided. If the toner does not remain on the transfer fixing roller 13, it may be omitted.

[Second Embodiment]
Next, a second embodiment of the fixing device unit employing the belt method in the image forming apparatus of the present invention will be described based on an enlarged side sectional view shown in FIG. In the second embodiment, a transfer fixing belt 33 is used as a transfer fixing member that contacts the downstream end of the intermediate transfer belt (intermediate transfer member) 2. The toner image transferred from the photoreceptor onto the intermediate transfer belt is further transferred from the intermediate transfer belt 2 onto the transfer fixing belt 33, and the fixing process is completed in the fixing nip. In the embodiment of the belt system, the transfer fixing belt 33 is used in place of the transfer fixing roller 13, but as a belt-specific effect, the distance from the fixing nip exit to the contact position with the intermediate transfer belt 2 is set. Since the transfer fixing belt 33 is cooled in the meantime, the intermediate transfer belt 2 can be increased in durability without being heated to high temperature, and the fixing power consumption can be greatly reduced. Since the operation of this embodiment apparatus is substantially the same as that of the first embodiment, description thereof will not be repeated.

  Each configuration described so far is a configuration in which the intermediate transfer member is brought into contact with the fixing roller 13, but a detailed configuration may be omitted, but a configuration in which the intermediate transfer member is not in contact may be used. In the transfer and fixing method as in each of the above-described embodiments, toner for image formation is on the surface of the fixing roller 13 (also referred to as a transfer and fixing roller), and is transferred to a recording medium when stopped when a machine abnormality occurs. If the toner remains unfixed and left in this state, the toner melts and becomes a fixed substance on the roller, which makes it difficult to clean. In order to prevent the fixing roller 13 from being further heated by adopting the transfer fixing system configuration, it is effective to adopt a non-contact configuration.

  According to the configuration in which the heating unit is movable as described above, not only the problem in the exemplified transfer fixing method but also the same problem in the normal fixing method apparatus that is not the transfer fixing method can be solved. In the case of the abnormal stop of the machine, in the case of the normal fixing method, there is a problem that the recording medium is wound around the nip part due to the winding or jamming. Abnormal stops are also a problem. According to the present invention, it is possible to solve the problem peculiar to the transfer and fixing method that the toner remains on the fixing roller 13 even if the recording medium does not come near.

[Third Embodiment]
In each of the embodiments described above, a halogen lamp is used as a heat source, but the heat source is not limited to this. For example, an induction heating method may be used as shown in the enlarged side sectional view of FIG. The overall schematic configuration of this embodiment may be substantially the same as that of the first embodiment (see FIG. 1), and only the configuration of the heating means is different. In the case of this method, as shown in FIG. 7 (the same reference numerals as in FIG. 4 indicate the same configuration), a heat generating layer made of a metal layer such as Ag is provided inside the transfer and fixing roller 13, and the transfer is performed. An eddy current is generated in the heat generating layer by the action of the induction coil 34 provided in the vicinity of the fixing roller 13, and the toner on the transfer fixing roller 13 is heated and the resin viscosity decreases, and the transfer fixing roller Fixing is performed on the paper P (recording sheet) at a nip portion constituted by 13 and the pressure roller 14.

  FIG. 8 shows a specific example of a movable mechanism in which the external heating means is an induction heating system. FIGS. 8A and 8B are views of the external heating unit viewed from the lateral direction. Similar to FIG. 3 of the first embodiment described above, the heating means is moved from the normal position (FIG. 8 (a)) just by changing from the radiant heating method to the induction heating method. The induction coil 34 constituting the heating means of the induction heating system is moved to the position shown in FIG. 8B (details of the drive unit will be described later).

  In this embodiment, as a method (driving unit) for moving the heating means, the sheet-like member is deformed depending on whether or not the above-described energization is performed. As shown in the figure, the induction coil 34 is held by the holding member 301. The holding member 301 of the induction coil 34 can move around the fulcrum 302, is pulled by the spring 305, and stops at the position of the stopper 304.

  In one embodiment of the illustrated movable mechanism, the sheet-like member 210 as an actuator has a flat shape as shown in FIG. 8B when not energized. It gradually bends in the direction of the arrow 8 (a) and moves up to a normal position while contacting the lower end (free end) 303 of the holding member 301. That is, when the apparatus is movable (when energized), the sheet-like member 210 is moved to the normal position as shown in FIG. 8A in response to voltage application, and the lower end (free end) of the holding member 301 is moved. ) 303 is pressed, but when it is not energized, it moves (returns) as shown in FIG. 8B to release the lower end (free end) 303 of the holding member 301 from the normal position. And moved by being pulled by the spring 305, and the heat source supply is turned off.

[Fourth Embodiment]
In the embodiments described so far, the example in which the transfer fixing unit is located obliquely below the belt has been described. However, the present invention is not limited to this arrangement form, and the conveyance path of the recording medium also in other arrangement configurations Although it changes, it can be made to correspond to each arrangement and the same effect is acquired. For example, as shown in the sectional side view of the main part of the tandem type color copying machine in FIG. 9, the image of the horizontal arrangement configuration in which the transfer fixing unit (nip part) is arranged in a straight line in the extending direction of the belt suspended horizontally. The present invention can also be applied to a forming apparatus, that is, a configuration in which the intermediate transfer side opening of the transfer fixing unit is lateral. In the image forming apparatus of the fourth embodiment shown in FIG. 9, only the arrangement position of the transfer and fixing unit is different, the other parts are the same as those in FIG. 1, and the same parts as those in FIG. Detailed description will be omitted. FIG. 10 ((a) to (b)) shows the transfer fixing portion in this embodiment. FIG. 10A shows the heating means in the normal state, and FIG. 10B shows the movable position / posture of the heating means at the time of abnormal stop. Also in this embodiment, the heating means is movable, and in the same way as already described, when the abnormal machine stop occurs, the reflector 32 is moved from the normal operation position to the position 32b to prevent the recording medium from being heated. There are effects such as prevention of temperature rise on the intermediate transfer member and prevention of heating of the fixing roller 13.

[Fifth Embodiment]
An embodiment of an image forming apparatus of external heating means of an induction heating system with a similar horizontal arrangement configuration is shown. In the fifth embodiment shown by the main part in FIG. 11 ((a) to (b)), the heating means is movable. As shown in FIGS. 11A and 11B, this embodiment is different from the fourth embodiment only in the configuration of the external heating means, and the other parts are the same as those of the fourth embodiment. Further, the external heating means and the movable mechanism may be the same as those in the third embodiment (see FIG. 8). The explanation of the equivalent parts and the explanation of the equivalent action of the apparatus will be omitted.

[Sixth Embodiment]
FIG. 12 shows a side view of another embodiment of the external heating means of the radiant heating method used in the previous fourth embodiment, the first embodiment, and the second embodiment. In the sixth embodiment, the shape of the opening of the reflector 32 constituting the radiant heating type external heating means is different from the conventional one. That is, with respect to the rotation direction of the fixing roller 13, when the upstream rising length is L1 and the downstream rising length is L2, L1> L2. Thereby, radiant heat and convection heat can be made difficult to escape from the upstream side, temperature rise to the surroundings can be prevented, and wasteful energy consumption of the heat source can be suppressed, leading to energy saving. In particular, in the transfer fixing system having the intermediate transfer member, since it is on the upstream side in the rotation direction of the fixing roller 13, there is an effect of suppressing the temperature rise to the intermediate transfer member.

  The reason why the downstream opening position need not be regulated as much as the upstream side is that the direction in which radiant heat or convection heat escapes is on the pressure roller 14 or the recording medium side, so those members are heated during normal operation. This is because there is no particular heat loss.

[Seventh Embodiment]
The position of the transfer fixing unit may be located above the intermediate transfer member. FIG. 13 is an enlarged side sectional view of the fixing device according to the seventh embodiment. In the present embodiment, the transfer fixing portion (nip portion) is disposed above the front end portion of the suspended belt. Also in this embodiment, the radiation heating type external heating means is movable. In this embodiment, only the arrangement position of the transfer fixing unit is different, and other parts not shown are the same as those in FIG. 1 (or FIG. 9), and detailed description thereof is omitted. In FIG. 13, the same reference numerals are given to equivalent parts. In this configuration, since the nip portion through which the recording medium passes is located above the external heating means, radiant heat from the heat source and particularly convection heat easily escape upward. For this reason, when an abnormal machine stop occurs, moving the reflector 32 from the normal operating position to the position 32a prevents problems such as preventing the recording medium from being heated, preventing the temperature of the intermediate transfer member from rising, and preventing the fixing roller 13 from being heated. The point resolution effect is greater. Note that the same effect can be obtained if the transfer fixing portion does not have to be directly above and is above the horizontal position of the opposing roller 9.

[Eighth Embodiment] (Reference Example)
Next, as another embodiment of the present invention, an embodiment in which a shutter member is provided between a heating member and external heating means will be described in detail with reference to FIG. FIG. 14A is a diagram illustrating the fixing unit in a normal state, and FIG. 14B is an explanatory diagram of the fixing unit illustrating the movable position / posture of the shutter member 401 at the time of abnormal stop. In the eighth embodiment of the present invention, when the heat insulating plate (shutter) 401a as the heat shielding member or the heat transfer inhibiting member is moved from the normal position to the abnormal stop position, it moves between the external heating means.

  The shutter member 401 is composed of a member with good heat insulation, can rotate around a fulcrum 402 coaxial with the transfer fixing roller 13, is pulled by a spring 403, and stops at the position of the stopper 404. A boss portion 405 is erected at one end of the shutter member 401 so as to be able to contact the free end of the sheet-like member 210 (in a curved state (when energized)). When the sheet-like member 210 having one end fixed is not energized, the sheet-like member 210 has a flat shape as shown in the position of FIG. The bend and the free end rise and move to the normal position while contacting the boss 405 of the shutter member 401. Correspondingly, the shutter member 401 is moved to the normal position against the spring 403 and held. Thereby, the radiant heat and convection heat from the external heating means are transmitted to the heating member side.

  At the time of non-energization due to occurrence of abnormality (control corresponding to abnormality or interruption of energization due to abnormality itself), the sheet-like member 210 moves as shown in FIG. Then, it rotates and moves, and the heat supply is turned off by the shutter 401a, so that heat transfer is suppressed. In this way, it is possible to suppress transmission of radiant heat or convection heat due to radiant heating or induction heating to the heating member side, and it is possible to suppress heating of the recording medium by raising the temperature of the fixing roller.

  Although the flowchart is omitted, the schematic operation of the eighth embodiment is substantially similar to that shown in the flowchart of FIG. 5, and the difference corresponds to the time of abnormality detection (S04: Yes) in FIG. After the external heating heat source OFF operation (S06), the intermediate transfer member is separated and the heat source is shut off (the shutter is movable) (these operations are performed when the heat source (moving the external heating means) in S07 in FIG. 5 is shut off). Equivalent). The subsequent operation is the same as in FIG. 5, a predetermined abnormality treatment is performed (S08), and if the abnormality detection signal is not detected again (by eliminating the abnormal state) (S09: Yes), the movable part or the like Returns to the normal position (S10) and returns to normal operation after warm-up (S01) (S02: standby).

[Ninth Embodiment] (Reference Example)
Next, a ninth embodiment in which the shutter shape is different will be described with reference to FIG. FIG. 15A is a diagram illustrating the fixing unit in a normal state, and FIG. 15B is an explanatory diagram of the fixing unit illustrating the movable position / posture of the shutter member and the like corresponding to the abnormal stop. As shown in FIG. 15, the shutter member 501 has a heat insulating plate 501a that is configured in substantially the same manner as in the previous embodiment and is equivalent to the shutter 401a in the previous embodiment, in addition to the intermediate transfer body 2 and the transfer fixing roller 13. Between these, a heat insulating plate (shutter) 501b is provided as a heat shielding member or a heat movement inhibiting member for suppressing heat radiation (heat movement) from the transfer fixing roller 13 to the intermediate transfer belt 2. As shown in the figure, these heat insulating plates 501a and 501b do not obstruct secondary transfer from the intermediate transfer belt 2 to the transfer fixing roller 13 during normal movement, and as much as possible to radiate heat to the intermediate transfer belt 2. In order to suppress, it is formed in a shape having an opening. The moving method of the shutter member 501 is based on the deformation depending on whether or not the sheet-like member 210 is energized, and is the same as in the above embodiment. At the time of non-energization due to the occurrence of abnormality (control corresponding to abnormality or interruption of energization due to abnormality itself), the sheet-like member 210 moves as shown in FIG. 15B, whereby the shutter member 501 is pulled by the spring 403. Then, the heat source is turned off by the heat insulating plate 501a, and the heat transfer from the transfer fixing roller 13 to the intermediate transfer body 2 is suppressed by the heat insulating plate 501b.

  In the present embodiment, the heat insulating plate is commonly used for the shutter member 401, but may be provided as a separate member. The heat transfer inhibiting member is preferably a plate having a metallic luster with a low emissivity, and an excellent effect can be obtained particularly when two metal sheets are arranged with a fine gap or a heat insulating material interposed therebetween. It is also conceivable to use a thin plate containing a micro heat pipe structure used for CPU cooling of a notebook computer. In this case, the heat transfer inhibiting member can be kept at a low temperature to suppress heat transfer. With the heat insulating plate 401, the temperature rise of the intermediate transfer member can be reduced to some extent, and thermal deterioration on the intermediate transfer member side can be suppressed. The heat insulating plate 501b may be provided on either the fixing device main body or the image forming apparatus main body.

[Tenth embodiment] (Reference example)
FIGS. 16 (a) to 16 (b) show an embodiment in which a heat source is shut off by a shutter, corresponding to the case where the heating means is an induction heating system. FIG. 16A is a view showing the heating means in the normal state, and FIG. 16B is an explanatory view showing the movable position / posture of the shutter member 601 at the time of abnormal stop. Only the heat insulating plates (shutters) 601a and 601b of the shutter member 601 having the same shape as that of FIG. 15 are shown, and the other portions and the sheet-like member 210 are not shown (equivalent to FIG. 15). In the case of the tenth embodiment, the shutter member 601 is preferably made of a metal, and particularly preferably a magnetic shield material, such as a ferromagnetic material such as ferrite. Since the magnetic field from the induction coil 33 is concentrated on the shutter 601a (magnetic shield material), it becomes difficult to be transmitted to the heating member side, so that the temperature rise can be suppressed. In addition, when there is a concern of heating by concentrating on the shutter 601a, as shown in FIG. 16C, it is more effective to have a two-layer structure in which a heat insulating member shutter 601c is further laminated on the heating member side. can get. In the embodiment of the induction heating method in FIG. 16 as well, the moving method of the shutter member 601 is exactly the same as in the case of the eighth and ninth embodiments described above, and is based on the deformation depending on whether or not the sheet-like member 210 is omitted. The description is omitted.

[Eleventh embodiment]
Although not shown in the drawings, as described in the ninth and tenth embodiments, in order to shut off the heat source when an abnormality occurs, the shutter member is provided between the heating member and the external heating means, which has already been described. As described above, the heating member may be moved at the same time. A flowchart in this case is shown in FIG. Corresponding to the abnormality detection (step; S04: Yes), after the external heating heat source OFF operation (S06), the intermediate transfer member is separated (S11), the external heating means is moved (S12: for example, if it is a radiant heating type) The reflector is moved according to the OFF operation of the connection SW, and the heat source is cut off), and the shutter is moved (S13 heat source cut off). Note that the order of the series of processes is not limited to that shown in the figure. Thereafter, a predetermined abnormality treatment is performed (S08), and if the abnormality detection signal is not detected again (by eliminating the abnormal state) (S09: Yes), the movable part returns to the normal position (S10), After warm-up (S01), the normal operation is resumed (S02: standby). By adopting such a combined configuration, it is possible to ensure double safety. When the heating member is a radiant heating method and the reflector 32 is moved, it can be moved even if the end position on the upstream side is higher (H1) than the lowest position of the fixing roller 13 as shown in FIG. is there. On the other hand, there is no problem if the downstream end position H2 is not in contact when it moves. The heating member may be of a movable induction heating type.

[Twelfth embodiment]
An embodiment in which spherical toner is used will be described. It is known that the transferability (transfer efficiency and fidelity) of toner from the intermediate transfer belt 2 to the transfer fixing member affects the image quality improvement, and this toner transferability is related to the shape of the toner. . The present embodiment aims to optimize the toner shape in order to achieve the high image quality in each of the above embodiments. The above-mentioned Patent Document 6 describes in detail that the transferability of a toner having a Wadel practical sphericity φ of 0.8 or more is improved, and this is also used in the above-described embodiments. High image quality can be achieved. Therefore, it is preferable to use a toner having a Wadel practical sphericity φ of 0.8 or more. Here, the sphericity φ is expressed by the following formula: φ = (diameter of circle equal to particle projection area) / (diameter of circle circumscribing the particle projection image)
It can be easily calculated by taking an appropriate amount of toner on a slide glass, enlarging (500 times) with a microscope, and measuring any 100 toners. In this embodiment, the secondary transfer efficiency and fidelity can be improved, and high image quality can be realized.

  The above embodiment has been described based on the drawing of the transfer fixing device provided with the intermediate transfer member. However, the present invention can be similarly applied to a known fixing device that does not use the intermediate transfer member. The effect can be obtained as well. That is, in any configuration, the recording medium is jammed by moving the heating direction of the external heating means in the opposite direction to the recording medium side at the nip forming portion or shutting off the heat source by the shutter member at the time of abnormality, and in the vicinity of the nip forming portion. Even if it remains, it can be prevented from being heated and is effective in ensuring safety.

  As described above, the present invention has been described mainly with the fixing unit. However, in the image forming apparatus of the present invention having the fixing device of the present invention as described above, as described above, the means for heating from the outside in the fixing unit. Therefore, the image forming apparatus as a whole can be secured as a suitable image forming apparatus that can ensure safety during an abnormality.

  The present invention is not limited to the fixing device and the image forming apparatus having the configuration described so far, and the present invention can be similarly applied to devices having other known configurations, and an equivalent effect can be obtained. If some examples are shown in FIG. 21 (the transfer fixing portion is obliquely configured), FIG. 22 (vertical arrangement form of each portion; the intermediate transfer member is located below, In an image forming apparatus having an intermediate transfer member having a structure as shown in FIG. 24 (free transfer belt system) and FIG. 25 (free transfer belt system), the transfer fixing unit is positioned above the temperature fixing unit. Deterioration of the image quality is a problem due to problems such as deterioration of the intermediate transfer member, toner deterioration due to temperature rise on the image forming portion, particularly the photosensitive member, toner fixation, and toner filming.

  Therefore, in each of the known configurations, the external heating means is configured to be movable according to the technique described as the embodiment of the present application, and / or is configured to be movable to a region between the external heating means and the heating member. By adopting a configuration with an added shutter, it is possible to solve a problem caused by overheating in the fixing unit at the time of abnormality, as in the above-described embodiment. In other words, as described above with reference to the embodiments, it is sufficient to apply the configuration shown in FIG. 3 or the configuration shown in FIG. 8 to the external heating means, and analogy including other modifications. Therefore, detailed description and illustration are omitted for the sake of simplification of the specification. In addition, the present invention can be similarly applied to the configuration (drum photoreceptor system) shown in [Patent Document 3] illustrated as FIG. 23, and by adopting the configuration described so far, It is possible to solve a problem caused by overheating in the fixing unit at the time of abnormality.

1 is a side cross-sectional view schematically showing a main part of a tandem type color copying machine according to a first embodiment of the present invention. (a) is a figure which shows the radiation heating system heating means in a normal state, (b) is a figure which shows the movable position and attitude | position at the time of an abnormal stop. (a) is a figure which shows the heating means seen from the longitudinal direction, (b) * (c) is a figure which shows the heating means seen from the horizontal direction. FIG. 3 is an enlarged side sectional view of the fixing device according to the first embodiment. 6 is a flowchart illustrating an example of an operation of the fixing device according to the first embodiment. FIG. 4 is an enlarged side sectional view showing a belt-type fixing device portion according to a second embodiment of the present invention. FIG. 10 is an enlarged side cross-sectional view illustrating another configuration example (third embodiment) of the fixing device. (a) is a figure which shows the induction heating system heating means in a normal state, (b) is explanatory drawing which shows the movable position and attitude | position at the time of an abnormal stop. It is a sectional side view which shows typically the principal part of the tandem type color copying machine which is 4th Embodiment of this invention. (a) is a figure which shows the heating means in a normal state, (b) is explanatory drawing which shows the movable position and attitude | position of a heating means at the time of an abnormal stop. It is a figure which shows the specific Example of the movable mechanism of an induction heating system external heating means. It is a side view which shows another embodiment about the external heating means of a radiant heating system. It is an expanded sectional side view of the fixing device of 7th Embodiment. (a) is a figure which shows the induction heating system heating means in the normal state in 8th Embodiment, (b) is explanatory drawing which shows the movable position and attitude | position at the time of an abnormal stop. (a) is a figure which shows the induction heating system heating means in the normal state in 9th Embodiment, (b) is explanatory drawing which shows the movable position and attitude | position at the time of an abnormal stop. (a) is a figure which shows the induction heating system heating means in the normal state in 10th Embodiment, (b) is explanatory drawing which shows the movable position and attitude | position at the time of an abnormal stop. 14 is a flowchart illustrating an example of an operation of a fixing device according to an eleventh embodiment. FIG. 3 is an enlarged side view of a main part showing a configuration of a known fixing device. FIG. 3 is an enlarged side view of a main part showing a configuration of a known fixing device. FIG. 3 is an enlarged side view of a main part showing a configuration of a known fixing device. It is a principal part enlarged side view which shows the structure of a well-known image forming apparatus. It is a principal part enlarged side view which shows the structure of a well-known image forming apparatus. It is a principal part enlarged side view which shows the structure of a well-known image forming apparatus. FIG. 3 is an enlarged side view of a main part showing a configuration of a known fixing device. FIG. 3 is an enlarged side view of a main part showing a configuration of a known fixing device.

Explanation of symbols

1A Image forming unit
1B Paper feed unit
2 Intermediate transfer belt (intermediate transfer member)
3Y, 3M, 3C, 3B photoconductor
4 Charging device
5 Writing device (optical writing means)
6 Developer
7 Primary transfer device
8 Cleaning device
9 Opposite roller (drive roller)
10 Followed roller
11 Cleaning device
12 Fixing device
13 Transfer fixing roller
14 Pressure roller (second transfer fixing roller)
15 (15 ') Halogen heater (external heating means)
16 Paper tray
17 Feed roller
19 Registration roller pair
32 (32 ') reflector (external heating means)
33 Transfer fixing belt
34 Induction coil (external heating means)
51 Tension roller
53 Pipe cored bar
61 Cleaning material
210 Sheet member
201 Reflector holding member
202 fulcrum
203 Lower end (free end)
204 Stopper
205 Spring
301 Holding member
302 fulcrum
303 Lower end (free end)
304 stopper
305 Spring
401 Shutter member
401a Insulation plate (shutter)
402 fulcrum
403 spring
404 stopper
405 Boss
501 Shutter member
501a, 501b Thermal insulation plate (shutter)
601 Shutter member
601a, 601b, 601c Insulation plate (shutter)
N (fixing) nip P paper (recording sheet)

Claims (6)

In a fixing device in which a nip is formed by a heating member and a pressure member, and an image is pressed and fixed on a recording medium passing through the nip.
Heating means for heating the heating member from the outside;
A sheet-like member that is deformed by the presence or absence of energization ;
Wherein the heating means is movable and has a movable unit having a power supply unit to the heating means,
When the sheet-like member is not energized, it is not in contact with the movable means, and the movable means is in a position where the heating means does not heat the heating member from the outside.
When the sheet-like member is energized, due to the deformation of the sheet-like member, the movable member comes into contact with the movable member, and the movable member is changed,
The fixing device characterized in that the movable means moves the heating means to a position where the heating member is heated from the outside . When the sheet-like member is not energized, the heat source supply by the heating means to the heating member, and the power supply to the heating means are stopped,
The fixing device according to claim 1 , wherein when the sheet-like member is energized, a heat source is supplied to the heating member by the heating unit and a power supply is supplied to the heating unit . The sheet-like member, the fixing device according to claim 1 or 2, characterized in that shape change by energizing the low voltage. When the sheet-like member is energized, it further has a shutter located outside the region between the heating means and the heating member,
Wherein when not energized to the sheet-like member, the fixing device according to any of claims 1 to move to Turkey and wherein the region 3 between the pre-Symbol shutter and the heating means and the heating member. Image forming apparatus characterized by claims 1 and is configured using a fixing device according to any one of 4. The image forming apparatus according to claim 5, wherein toner having a Wadel practical sphericity φ of 0.8 or more is used as a developer.

Images