JP2016218239A - Fixing device and image forming apparatus including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device capable of suppressing the generation of an ultrafine particle in fixation processing by suppressing the excessive temperature rise of the end of a rotating body to be heated with a simple configuration and to provide an image forming apparatus including the fixing device.SOLUTION: The fixing device includes the rotating body to be heated which is heated by an incorporated heat source and a pressure member which comes into contact with the rotating body to be heated, to form a fixing nip part. The fixing device includes, as the heat source, a first heat source which heats the almost central part of a maximum passage area through which a maximum recording medium passes in the rotation axis direction of the rotating body to be heated and a second heat source which heats both ends of the maximum passage area and a non-passage area outside the maximum passage area. A first temperature detection device which detects the temperature of the almost central part of the maximum passage area and a second temperature detection device which detects the temperature of the non-passage area outside the maximum passage area are arranged to face the outer peripheral surface of the rotating body to be heated. A distance between the second heat source and the second temperature detection device in the radial direction of the rotating body to be heated is shorter than a distance between the first heat source and the first temperature detection device.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a fixing device used in an image forming apparatus such as a copying machine, a printer, a facsimile machine, or a multifunction machine thereof, and an image forming apparatus including the fixing device, and more particularly to a fixing device that suppresses generation of ultra fine particles inside the fixing device. And an image forming apparatus including the same.

  In an image forming apparatus using an electrophotographic system, toner is applied to an electrostatic latent image formed on a photosensitive member to form a toner image, and the toner image is transferred onto a sheet. Is established.

  In a heating-type fixing device that fixes a toner image on a sheet by heating the sheet, ultra fine particles (UFP) generated due to the heating may be scattered inside the image forming apparatus. . In recent years, it has been desired to suppress the dispersion of ultra fine particles (UFP) to the outside of the device due to the growing awareness of environmental issues. Ultra fine particles (UFP) refer to particles (nanodust) having a diameter of 100 nm or less among suspended particulate matter (SPM). It has been found that the ultra fine particles (UFP) are mainly generated from a silicone rubber used as an elastic layer such as a heating roller or a pressure roller, or a heat absorbing portion formed on the inner peripheral surface of the heating roller.

  For example, in order to efficiently absorb the radiant heat from the heat source arranged inside the heating roller and to transfer the heat to the heating roller, the heat absorption part is Sermo Black, Okitsumo Paint, Tetzol (all are trade names), etc. The black paint is used. These black paints are produced by adding a modified silicone to a metal oxide. When the temperature of the heat absorbing portion is increased by the heat source, there is a problem that low molecular siloxane is generated from the modified silicone of the heat absorbing portion and this siloxane is emitted as ultra fine particles (UFP).

  Therefore, a technique for removing ultrafine particles (UFP) is known. For example, Patent Document 1 discloses a fixing device including an ultrafine particle removing device having a suction fan, a dust collection filter, and a duct. In this fixing device, the air flow generated by the suction fan flows in the duct from the vicinity of the side surface of the fixing roller, and then is discharged to the outside of the image forming apparatus through the dust collecting filter. At this time, ultra fine particles (UFP) generated from a heating roller having an elastic layer of silicone rubber flow in the duct together with the air flow and are collected by a dust collecting filter.

  In addition, when the size of the paper to be passed is smaller than the axial dimension of the heating roller, heat is not lost to the paper in the area (non-sheet passing portion) where the paper does not pass on the outer peripheral surface of the heating roller. The surface temperature rises as compared with the area (sheet passing portion) through which the sheet passes and accumulates on the roller. As a result, the black paint applied to the inner surface of the non-sheet passing portion of the heating roller and the ultra fine particles (UFP) are likely to be generated from the vicinity of the surface layer portion of the non-sheet passing portion of the pressure roller facing the heating roller.

  Therefore, in Patent Document 2, a fixing belt is bridged between the first and second heating rollers and a small-diameter roller having a heat insulating layer disposed downstream of the second heating roller in the conveyance direction of the recording material. A heat source having a light emitting region at a position corresponding to the thin region, with the central portion being thinner than the end in the axial direction and the second heating roller being thinner than the central portion in the axial direction. A fixing device is disclosed in which a uniform temperature distribution can be obtained in the axial direction of the heating roller regardless of the sheet passing width.

JP 2012-47790 A JP 2009-251180 A

  However, in the method of Patent Document 1, it is necessary to provide a suction fan, a dust collection filter, and a duct inside the image forming apparatus, which leads to an increase in the size of the image forming apparatus and is disadvantageous in terms of cost. Further, in the method of Patent Document 2, it is necessary to use two heating rollers whose thickness is changed in the axial direction, which complicates the configuration of the fixing device.

  SUMMARY OF THE INVENTION In view of the above problems, the present invention provides a fixing device capable of suppressing the generation of ultrafine particles during fixing processing by suppressing excessive temperature rise at the end of the heated rotating body with a simple configuration, and an image including the same. An object is to provide a forming apparatus.

  In order to achieve the above object, a first configuration of the present invention is a fixing device having a heated rotating body and a pressure member. The heated rotating body is heated by a built-in heat source. The pressure member is in contact with the heated rotating body to form a fixing nip portion. Then, the unfixed toner image on the recording medium is melt-fixed by heating and pressurizing the recording medium passing through the fixing nip portion. The fixing device has, as heat sources, a first heat source that heats a substantially central portion of a maximum passage area through which the largest recording medium passes in the rotation axis direction of the heated rotating body, both ends of the maximum passage area, and the outside of the maximum passage area. And a second heat source for heating the non-passing region. In addition, an outer peripheral surface of the heated rotating body includes a first temperature detection device that detects a temperature at a substantially central portion of the maximum passage region and a second temperature detection device that detects a temperature of a non-passage region outside the maximum passage region. The distance between the second heat source and the second temperature detection device in the radial direction of the rotating body to be heated is shorter than the distance between the first heat source and the first temperature detection device.

  According to the first configuration of the present invention, the second temperature detection device that detects the temperature of the non-sheet passing region of the heated rotating body is disposed close to the second heat source. When energization to the heat source is simultaneously turned ON, the timing at which the temperature of the non-passing region exceeds the threshold by the second temperature detection device is detected by the first temperature detection device. It will be earlier than the timing of detecting this. Therefore, the timing for turning off the energization of the second heat source is also accelerated, and the energization time of the second heat source can be reduced. As a result, even when the control temperature by the second temperature detection device is set to be the same as the conventional temperature, the temperature of the non-passing region can be controlled lower than the conventional temperature, and the energization time to the second heat source is shortened. Since the thermal shock due to the energization of the second heat source is also suppressed, it is possible to effectively generate ultrafine particles from the heat absorbing portion in the non-passing region of the heated rotating body and the elastic layer in the non-passing region of the pressure member. It becomes possible to suppress.

1 is a side sectional view showing an internal structure of an image forming apparatus 100 including a fixing device 15 according to an embodiment of the present invention. Side sectional view of the fixing device 15 of the present embodiment. Sectional drawing which shows the state which cut | disconnected the heating roller 30 used for the fixing apparatus 15 of this embodiment along an axial direction. Perspective view of heating roller 30 Graph showing the relationship between the surface temperature of the heating roller 30 and the number of ultrafine particles generated Side surface sectional view showing the positional relationship between the second temperature sensor 41 and the fixing nip portion N in the circumferential direction of the heating roller 30.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a side sectional view showing an internal structure of an image forming apparatus 100 including a fixing device 15 according to an embodiment of the present invention. In the image forming apparatus (for example, a monochrome printer) 100, an image forming unit P that forms a monochrome image by each process of charging, exposure, development, and transfer is disposed. In the image forming portion P, along the rotation direction of the photosensitive drum 5 (clockwise direction in FIG. 1), the charging unit 4, the exposure unit (laser scanning unit, etc.) 7, the developing unit 8, the transfer roller 14, and the cleaning device 19 and a static eliminator (not shown) are disposed.

  When the image forming operation is performed, the photosensitive drum 5 rotating in the clockwise direction is uniformly charged by the charging unit 4, and the electrostatic latent image is formed on the photosensitive drum 5 by the laser beam from the exposure unit 7 based on the document image data. An image is formed, and a developer (hereinafter referred to as toner) is attached to the electrostatic latent image by the developing unit 8 to form a toner image.

  The toner is supplied to the developing unit 8 from the toner container 9. The image data is transmitted from a personal computer (not shown) or the like. Further, a static elimination device (not shown) for removing residual charges on the surface of the photosensitive drum 5 is provided on the downstream side of the cleaning device 19 with respect to the rotation direction of the photosensitive drum 5.

  A sheet is conveyed from the sheet feeding cassette 10 or the manual sheet feeder 11 via the sheet conveying path 12 and the registration roller pair 13 toward the photosensitive drum 5 on which the toner image is formed as described above, and the transfer roller 14. The toner image formed on the surface of the photosensitive drum 5 is transferred onto the sheet by (image transfer unit). The sheet on which the toner image has been transferred is separated from the photosensitive drum 5 and conveyed to the fixing device 15 to fix the toner image. The sheet that has passed through the fixing device 15 is conveyed to the upper part of the apparatus through the sheet conveying path 16, and is discharged to the discharge tray 18 by the discharge roller pair 17 when an image is formed on only one side of the sheet (during single-sided printing).

  On the other hand, when images are formed on both sides of a sheet (during double-sided printing), the conveyance direction is reversed after the trailing edge of the sheet has passed through the curved portion 20 of the sheet conveyance path 16. As a result, the paper is distributed to the reverse conveyance path 21 branched from the curved portion 20, and is re-conveyed to the registration roller pair 13 with the image surface reversed. Then, the next toner image formed on the photosensitive drum 5 is transferred by the transfer roller 14 to the surface on which the sheet image is not formed. The sheet on which the toner image has been transferred is conveyed to the fixing device 15 where the toner image is fixed, and then discharged onto the discharge tray 18 by the discharge roller pair 17.

  FIG. 2 is a side sectional view of the fixing device 15 mounted on the image forming apparatus 100. The fixing device 15 includes a heating roller 30 that is a heated rotating body, a pressing roller 31 that is a pressing member, a first heater 35 that heats the heating roller 30, a second heater 37, and a surface temperature of the heating roller 30. This is a roller fixing system including a first temperature sensor 40 and a second temperature sensor 41 that detect the above. In FIG. 2, the first temperature sensor 40 and the second temperature sensor 41 are arranged so as to overlap in a direction perpendicular to the paper surface. Further, the description of the housing of the fixing device 15 is omitted.

  The heating roller 30 has an elastic layer 30b made of silicone rubber or the like formed on the outer peripheral surface of a cylindrical cored bar 30a made of a metal base tube such as aluminum or iron having excellent heat conductivity. What coat | covered the mold release layer (not shown) used is used.

  As a specific configuration of the heating roller 30 used in the present embodiment, for example, a 6.5 mm thick silicone rubber layer is laminated as an elastic layer 30b on the outer peripheral surface of an aluminum cored bar 30a having an outer diameter of 27 mm, Examples of the release layer include a laminate of a PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer) layer having a thickness of 25 μm.

  A heat absorbing portion 33 is formed on the inner peripheral surface of the cored bar 30 a of the heating roller 30. The heat absorbing portion 33 has a length equal to or greater than the maximum sheet width (maximum sheet passing width) of the maximum size (for example, A3 size) inserted through the fixing nip portion N in the axial direction of the heating roller 30. It is formed over the entire circumference of the inner circumferential surface. In the present embodiment, the heat absorbing portion 33 is formed from one end portion in the axial direction to the other end portion of the cored bar 30a. The heat absorption part 33 consists of a black paint (for example, Okitsumo paint No. 8264: trade name) baked on the inner peripheral surface of the cored bar 30a.

  Inside the metal core 30 a of the heating roller 30, two heaters (heat sources) including a first heater 35 and a second heater 37 such as a halogen lamp that generate radiant heat are provided. By applying black coating on the inner peripheral surface of the core 30a heated by the first heater 35 and the second heater 37, the absorption rate of infrared rays (radiant heat) generated from the first heater 35 and the second heater 37 is increased. . As a result, the core metal 30 a can be efficiently heated by the first heater 35 and the second heater 37.

  In the pressure roller 31, an elastic layer 31b such as silicone rubber is formed on a cylindrical base 31a made of synthetic resin, metal or other material, and a release layer such as a fluororesin coat is formed on the surface of the elastic layer 31b. The one coated with (not shown) is used.

  As a specific configuration of the pressure roller 31 used in the present embodiment, for example, a 6.5 mm-thick silicone rubber layer is laminated as an elastic layer 31b on the outer peripheral surface of a base 31a having an outer diameter of 12 mm, and a release layer is formed. And a tube material made of PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer).

  The pressure roller 31 is pressed against the heating roller 30 with a predetermined pressure. When the heating roller 30 is driven to rotate in the clockwise direction of FIG. 2 by a motor (not shown), the pressure roller 31 is driven to rotate counterclockwise in FIG. 2 as the heating roller 30 rotates. A fixing nip portion N is formed at a portion where the heating roller 30 and the pressure roller 31 come into contact with each other while rotating in reverse. The pressure roller 31 may be driven to rotate by a motor, and the heating roller 30 may be driven to rotate as the pressure roller 31 rotates.

  The sheet is conveyed from the upstream side in the sheet conveyance direction (right side in FIG. 2) to the fixing nip portion N, and heated and pressed by the heating roller 30 and the pressure roller 31 in the fixing nip portion N, thereby The unfixed toner in powder state is melted and fixed. The sheet after the fixing process is separated from the surface of the heating roller 30 by a separation claw (not shown), and then conveyed downstream of the fixing device 15 (left side in FIG. 2) in the sheet conveying direction.

  FIG. 3 is a cross-sectional view (cross-sectional view taken along the line AA ′ in FIG. 2) showing a state in which the heating roller 30 used in the fixing device 15 is cut along the axial direction, and FIG. 4 is a perspective view of the heating roller 30. It is. The first heater 35 has a heat generating portion 35 a in the center portion in the longitudinal direction, and heats the substantially center portion of the heating roller 30 with the maximum sheet passing width W. The 1st heater 35 is arrange | positioned in the rotation center of the metal core 30a.

  The second heater 37 has two heat generating portions 37a at both ends in the longitudinal direction, and a region extending from both ends of the maximum sheet passing width W of the heating roller 30 to the non-sheet passing region R outside the maximum sheet passing width W. Heat. The second heater 37 is disposed at a position closer to the inner peripheral surface of the core metal 30a than the first heater 35.

  In the image forming apparatus 100 corresponding to a high-speed machine or a large size sheet (A3 size), when only the first heater 35 that heats the substantially central portion of the maximum sheet passing width W is used, a large size sheet is fed to the fixing nip portion N. When the paper is continuously fed, the surface temperature is lowered at the end of the paper feeding area of the heating roller 30. In order to suppress this phenomenon, the second heater 37 is used to positively heat the end of the sheet passing area of the heating roller 30 to suppress the occurrence of fixing failure due to insufficient temperature at the end of the sheet.

  As described above, the core metal 30a of the heating roller 30 is made of a material having high thermal conductivity such as aluminum. Therefore, when only the both ends of the maximum sheet passing width W (inside the maximum sheet passing width W) are heated by the second heater 37, the heat supplied from the second heater 37 is conducted in the roller axial direction and is not in the non-sheet passing region R. To spread. Furthermore, since the heat is taken away by the paper when the maximum size paper is continuously passed through the fixing nip portion N, the heat supply from the second heater 37 cannot catch up. Therefore, the second heater 37 is configured to heat from both ends of the maximum sheet passing width W to the non-sheet passing region R outside the maximum sheet passing width W.

  A first temperature sensor 40 and a second temperature sensor 41 made of a thermistor or the like are disposed in the vicinity of the outer peripheral surface of the heating roller 30. The first temperature sensor 40 is disposed to face a substantially central portion of the maximum sheet passing width W of the heating roller 30 and detects the surface temperature of the sheet passing region of the heating roller 30. The second temperature sensor 41 is disposed to face the non-sheet passing region R outside the maximum sheet passing width W of the heating roller 30 and detects the surface temperature of the non-sheet passing region R of the heating roller 30.

  The surface temperature of the paper passing area and the non-paper passing area of the heating roller 30 is detected by the first temperature sensor 40 and the second temperature sensor 41, and when the detected temperature falls below a predetermined threshold, the first heater 35 and the second heater The energization to 37 is turned on, and the fixing temperature is controlled by turning off the energization to the first heater 35 and the second heater 37 when the detected temperature exceeds a predetermined threshold.

  Since the first temperature sensor 40 is disposed within the maximum sheet passing width W, it is necessary to dispose a non-contact thermistor close to the outer peripheral surface of the heating roller 30. On the other hand, since the second temperature sensor 41 is disposed in the non-sheet passing region R, a contact type thermistor may be disposed in contact with the outer peripheral surface of the heating roller 30, or the non-contact type thermistor is heated. You may arrange | position close to the outer peripheral surface of the roller 30. FIG.

  By the way, the heat absorption part 33 (black paint) provided on the inner peripheral surface of the cored bar 30a of the heating roller 30 is obtained by adding a modified silicone to a metal oxide. When the temperature of the heat absorption part 33 rises by the first heater 35 and the second heater 37, siloxane is generated from the modified silicone of the heat absorption part 33, and the siloxane is diffused around the heat absorption part 33 as ultrafine particles (UFP). .

  In particular, when a large-size sheet is continuously passed through the fixing nip N, the second heater 37 heats the area from the both ends of the maximum sheet passing width W to the non-sheet passing area R as described above. In the non-sheet passing region R where the sheet does not pass, the sheet is not deprived of heat and the temperature of the cored bar 30a rises compared to the inside of the maximum sheet passing width W. Although the image quality is not affected even if the temperature of the non-sheet passing region R is increased, if the temperature of the non-sheet passing region R is increased, the heat absorbing portion 33 on the inner peripheral surface of the non-sheet passing region R of the heating roller 30. Then, ultrafine particles are generated from the elastic layer 31b in the non-sheet passing region of the pressure roller 31.

  FIG. 5 is a graph showing the relationship between the surface temperature of the heating roller 30 and the number of ultrafine particles generated. As is clear from FIG. 5, it can be seen that the amount of ultrafine particles generated abruptly increases from the time when the surface temperature of the heating roller 30 exceeds a certain temperature (about 180 ° C.). Since the temperature inside the heating roller 30 provided with the heat absorption part 33 is about 30 ° C. higher than the surface temperature of the heating roller 30, the ultrafine particles when the temperature inside the heating roller 30 exceeds 210 ° C. It is thought that the amount of generation increases.

  Further, it is known that even when the surface temperature of the heating roller 30 is the same, more ultrafine particles are generated when the heater is turned on than when the heater is turned off. Therefore, in addition to the condition that the temperature is high, ultrafine particles have a tendency to occur more frequently when the temperature fluctuates in the direction of even a slight increase. It is thought that many ultrafine particles are generated.

  Here, even if the surface temperature of the sheet passing area is controlled to be equal to or lower than the temperature (180 ° C.) at which the ultrafine particles are rapidly generated by the first temperature sensor 40, the surface temperature of the non-sheet passing area R is higher than the sheet passing area. Therefore, the generation of ultra fine particles cannot be prevented. On the other hand, if the second temperature sensor 41 is used to control the surface temperature of the non-sheet passing region R to a temperature (180 ° C.) or less at which the ultrafine particles are suddenly generated, large-size sheets are continuously fed to the fixing nip N. When paper is passed, the surface temperature is lowered at the end of the paper passing area, and fixing failure occurs due to insufficient temperature at the paper end.

  Therefore, in the present embodiment, as shown in FIGS. 2 and 3, the second heater 37 that heats both axial ends of the heating roller 30 is replaced by the first heater 35 that heats the axial central portion of the heating roller 30. Are also arranged at a position close to the inner peripheral surface of the heating roller 30 (core metal 30a). The distance d2 between the second heater 37 and the second temperature sensor 41 is made shorter than the distance d1 between the first heater 35 and the first temperature sensor 40.

  Since the first temperature sensor 40 that detects the temperature of the paper passing area of the heating roller 30 is located far from the first heater 35, the first temperature sensor 40 passes the current through the first heater 35 after energization is turned on. The timing for detecting that the temperature of the paper area exceeds the threshold value is delayed. As a result, the timing for turning off the energization of the first heater 35 is also delayed, and the time from when the energization to the first heater 35 is turned on until it is turned off (the energization time) becomes longer. Heating is accelerated. However, since the paper passing through the fixing nip portion N takes the heat of the heating roller 30 in the paper passing area, the temperature rise is reduced.

  On the other hand, in the non-sheet passing area of the heating roller 30, the temperature is likely to rise because the paper that takes the heat of the heating roller 30 does not pass, but the second temperature sensor detects the temperature of the non-sheet passing area of the heating roller 30. 41 is disposed close to the second heater 37. Therefore, when energization to the first heater 35 and the second heater 37 is simultaneously turned ON, the timing at which the second temperature sensor 41 detects that the temperature of the non-sheet passing region exceeds the threshold is the first temperature sensor. 40 is earlier than the timing for detecting that the temperature of the sheet passing area exceeds the threshold. As a result, the timing for turning off the energization to the second heater 37 is also advanced, and the time from when the energization to the second heater 37 is turned on until it is turned off is shortened. This is the direction in which the heating is suppressed.

  By adopting the configuration of the present embodiment, even when the control temperature (threshold) by the second temperature sensor 41 is set to the same as the conventional setting, the temperature of the non-sheet passing region can be controlled to be lower than the conventional one. Furthermore, since the energization time to the second heater 37 is shortened, thermal shock due to lighting of the second heater 37 is also suppressed. Accordingly, it is possible to effectively suppress the generation of ultrafine particles from the heat absorbing portion 33 in the non-sheet passing region of the heating roller 30 and the elastic layer 31b in the non-sheet passing region of the pressure roller 31.

  In the present embodiment, the second temperature sensor 41 is arranged at a position close to the fixing nip portion N on the upstream side in the rotation direction of the heating roller 30. Specifically, as shown in FIG. 6, a straight line L1 passing through the rotation center O of the heating roller 30 and the fixing nip N, and a straight line L2 passing through the rotation center O of the heating roller 30 and the second temperature sensor 41 Is arranged so that the angle θ formed by is within 90 °.

  When the energization time of the second heater 37 is decreased, there is a possibility that the fixing property at the end in the width direction when large-size paper is continuously fed may be hindered. Therefore, the temperature of the non-sheet passing region immediately before the sheet passes through the fixing nip N is detected by arranging the second temperature sensor 41 at a position close to the fixing nip N on the upstream side in the rotation direction of the heating roller 30. The gap between the temperature detected by the second temperature sensor 41 and the temperature of the non-sheet passing region of the heating roller 30 at the fixing nip N can be reduced.

  Further, in the present embodiment, the heat generating portion 37a of the second heater 37 is set to a length that overlaps the end portion in the width direction of the large size sheet (the both end portions of the maximum sheet passing width W). For example, as shown in FIG. 3, the length of the heat generating portion 37a is set to about twice the length of the non-sheet passing region R, and the heat generating portion 35a of the first heater 35 is set between the two heat generating portions 37a. The length is set.

  With the above configuration, the temperature at both ends of the maximum sheet passing width W can be controlled more finely by turning the second heater 37 on and off. Therefore, the temperature of the non-sheet-passing area of the heating roller 30 can be kept low without significantly reducing the fixing property at the end of the sheet-passing area. Coexistence with the fixing property in the part can be achieved. Furthermore, the effect which suppresses generation | occurrence | production of the ultrafine particle (UFP) by the temperature rise of a non-sheet passing area | region can also be anticipated.

  In this embodiment, the elastic layer 30 b is provided on the heating roller 30. However, in the fixing device 15 mounted on a monochrome printer or a monochrome copying machine as illustrated in FIG. 1, the elastic layer 30 b is not provided as the heating roller 30. Moreover, you may use the hard roller which provided only the mold release layer in the outer peripheral surface of the metal core 30a. On the other hand, in the fixing device 15 mounted on a color printer or color copier, the amount of unfixed toner on the sheet increases, so it is necessary to provide an elastic layer 30b on the heating roller 30 to increase the nip width of the fixing nip portion N. is there.

  When the elastic layer 30b is provided on the heating roller, the elastic layer 30b of the heating roller 30 includes the second temperature sensor 41 as shown in FIG. 3 in order to detect the increase in the surface temperature of the heating roller 30 more accurately. It is preferable to arrange it facing the portion where it is not formed.

  According to the present embodiment, it is possible to effectively reduce the amount of ultrafine particles (UFP) generated from the heating roller 30 and the pressure roller 31. It is also an effective ultrafine particle (UFP) reduction means in environmental certification tests and the like.

  In addition, this invention is not limited to the said embodiment, A various change is possible in the range which does not deviate from the meaning of this invention. For example, in the above embodiment, heaters that generate radiant heat such as halogen lamps are used as the first heater 35 and the second heater 37, but other heat sources may be provided.

  Further, the present invention is not limited to the monochrome printer as shown in FIG. 1, and other types of image forming including a roller heating type fixing device such as a color printer, monochrome and color copying machine, digital multifunction peripheral, or facsimile machine. Of course, it can also be applied to devices.

  In the present invention, a recording medium is inserted into a fixing nip formed by a heated rotating body heated by a heat source and a pressure member that contacts the heated rotating body with a predetermined pressure, and the recording medium is carried on the recording medium. The present invention can be used for a fixing device that fixes an unfixed toner image. By utilizing the present invention, it is possible to provide a fixing device capable of suppressing the generation of ultrafine particles during the fixing process by suppressing the excessive temperature rise at the end of the heated rotating body with a simple configuration.

15 Fixing device 30 Heating roller (heated rotating body)
30a Core 30b Elastic layer 31 Pressure roller (Pressure member)
31a Base 31b Elastic layer 33 Heat absorption part 35 1st heater (1st heat source)
35a Heating part 37 Second heater (second heat source)
37a Heat generation part 40 1st temperature sensor (1st temperature detection apparatus)
41 Second temperature sensor (second temperature detector)
100 Image forming apparatus W Maximum sheet passing width R Non-sheet passing area

Claims (5)

A heated rotating body heated by a built-in heat source;
A pressure member that forms a fixing nip portion in contact with the heated rotating body;
Have
In a fixing device that melts and fixes an unfixed toner image on a recording medium by heating and pressurizing the recording medium passing through the fixing nip portion,
The heat source includes: a first heat source that heats a substantially central portion of a maximum passage region through which the largest recording medium passes in the rotation axis direction of the heated rotating body; and both end portions of the maximum passage region and the maximum passage region. A second heat source that heats the outer non-passage area;
A first temperature detecting device for detecting a temperature at a substantially central portion of the maximum passage region;
A second temperature detection device that detects the temperature of the non-passage region outside the maximum passage region, and is disposed to face the outer peripheral surface of the heated rotating body,
The fixing device, wherein a distance between the second heat source and the second temperature detection device in a radial direction of the heated rotating body is shorter than a distance between the first heat source and the first temperature detection device.   The said 1st heat source is arrange | positioned in the rotation center of the said to-be-heated rotary body, and the said 2nd heat source is arrange | positioned in the radial direction outer side from the rotation center of the to-be-heated rotary body. The fixing device described. The second temperature detection device is disposed upstream of the fixing nip portion with respect to the rotation direction of the heated rotating body,
An angle formed by a straight line passing through the rotation center of the heated rotating body and the fixing nip portion and a straight line passing through the rotation center of the heated rotating body and the second temperature detecting device is within 90 °. The fixing device according to claim 1, wherein the fixing device is characterized in that: The heated rotating body has a cylindrical cored bar, and an elastic layer formed in at least the maximum passage region of the outer peripheral surface of the cored bar,
4. The fixing device according to claim 1, wherein the elastic layer is not formed at an end portion of the core metal facing the second temperature detection device. 5.   An image forming apparatus comprising the fixing device according to claim 1.

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