JP2009103873A - Fixing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing device which is capable of saving power and increasing the heat generation efficiency of a heating part. <P>SOLUTION: The fixing device 5 fixes a toner image transferred to a recording paper by the heating part 52 and a pressure part 56 and conveys the recording paper. The heating part includes: a microwave radiation part 533 which radiates microwave; a microwave absorbing body 54 which is heated by the microwave radiated from the microwave radiation part; and a rotating body 55 which is heated by heat conduction from the heated microwave absorbing body and is made into such a state that the rotating body 55 and the pressure part are pressed against each other, to form a nip portion 50. The microwave absorbing body is formed to be long in a direction orthogonal to the conveying direction of the recording paper and fixedly supported in the vicinity of the nip portion inside the rotating body. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fixing device provided in an image forming apparatus such as a copying machine, a facsimile machine, a printer, or a multifunction machine having these functions, and more particularly to a fixing device using microwaves.

As the image forming apparatus as described above, a pair of conveyance rollers (registration roller pair) installed in the middle of the recording sheet conveyance path, which feeds out sheets (recording sheets) one by one from a sheet supply unit provided with a sheet cassette or the like. Then, an image is recorded by an electrophotographic image recording unit.
The toner image formed on the surface of the photosensitive drum is transferred to the recording paper conveyed and supplied to the nip portion between the photosensitive drum and the transfer roller constituting the image recording unit. The toner image transferred to the recording paper is fixed as a permanent image by a fixing device installed in the middle of the recording paper conveyance path, and then discharged to a discharge tray.

Examples of the fixing device provided in the image forming apparatus include those provided with a heat roller and a press roller that rotate while being pressed against each other. Such a fixing device fixes a toner image transferred onto a recording sheet as a permanent image by heating and pressing at a nip portion between a heat roller and a press roller.
As the heat roller, a roller made of a hollow cylinder of aluminum or the like, in which a heating element such as a halogen lamp is accommodated, and the hollow cylinder is heated by the halogen lamp is often used.

The heat roller containing the halogen lamp as described above has a problem that power consumption is large and a warm-up time until a predetermined temperature is reached after the power is turned on.
In Patent Document 1 and Patent Document 2 described below, a fixing device using a microwave is proposed in order to solve the above problems.

  The fixing device described in Patent Document 1 includes a microwave irradiating unit that irradiates the printing paper with microwaves to fix the toner image on the printing paper during the fixing operation, and stops microwave irradiation except during the fixing operation. ing. The microwave irradiating means is installed above the printing paper to be conveyed, and is configured to melt the toner and fix the toner image by irradiating the microwave.

The fixing device described in Patent Document 2 includes a hollow cylindrical fixing roller that houses a microwave radiation device, and a pressure roller that is pressed against the fixing roller.
The fixing roller includes a cylindrical body made of a material easy to pass microwaves, an elastic layer easily passed through microwaves formed on the outer peripheral surface of the cylindrical body, and a surface layer coated on the surface of the elastic layer. It is configured. The microwave radiation device is supported in a fixed state in the fixing roller and radiates microwaves toward the contact portion between the fixing roller and the pressure roller. In this fixing device, the dielectric constant of the toner image is larger than the dielectric constant of the fixing roller, and the emitted microwave is absorbed into the toner image, so that the toner image is dissolved and fixed. Yes.
Further, in Patent Document 2, there is a description that the elastic layer may be a material that easily absorbs microwaves. In this case, the elastic layer is heated by the radiated microwave, and the elastic layer The toner image is heated and dissolved to be fixed.
JP 2000-98800 A (see FIG. 4) Japanese Unexamined Patent Publication No. 2007-121371 (see FIG. 7)

  However, the fixing device proposed in Patent Document 1 is configured to melt the toner by directly irradiating the toner with microwaves. Therefore, it is necessary to use a special toner having a large dielectric loss coefficient, and there is a problem in that an inexpensive toner that is widely used cannot be used. Further, in the fixing by direct irradiation with microwaves, there is a possibility that the pressure is not applied and the toner image is not sufficiently fixed.

In the fixing device proposed in Patent Document 2, since the fixing is performed by the fixing roller and the pressure roller, it is considered that the fixing by the pressure is sufficiently performed. Further, in the case where the elastic layer of the fixing roller is heated by microwaves and the toner image is heated and fixed by the heat generated by the elastic layer, it is considered that sufficient fixing can be performed even when an inexpensive toner is used. .
However, in the fixing device described in Patent Document 2, since the elastic layer is formed and rotated over the entire outer peripheral surface of the cylinder of the fixing roller, the heat generation efficiency of the elastic layer is There was a problem of being bad. That is, the elastic layer heated by the microwave radiated from the microwave radiating device supported in a fixed state in the fixing roller is configured to repeat heat generation and heat dissipation along with its rotation. There was a problem that its own heat generation efficiency was poor.

  The present invention has been proposed to solve the above-described problems, and an object of the present invention is to provide a fixing device that can save power and improve the heat generation efficiency of a heating unit.

  In order to achieve the above object, a fixing device according to the present invention is a fixing device that fixes a toner image transferred to a recording sheet by a heating unit and a pressing unit and conveys the recording sheet, The heating unit includes a microwave radiating unit that radiates microwaves, a microwave absorber that is heated by the microwave radiated from the microwave radiating unit, and heat conduction from the heated microwave absorber. A rotating body that is heated and pressed against each other to form a nip portion, and the microwave absorber is elongated along a direction orthogonal to the conveyance direction of the recording paper And fixedly supported in the vicinity of the nip portion inside the rotating body.

  In the fixing device of the present invention, the rotating body may be a cylindrical roller body. Alternatively, in the fixing device of the present invention, the rotating body may be an endless belt-shaped fixing film.

According to the fixing device according to the present invention, the heating unit is configured to heat the microwave absorber by the microwave radiating unit that radiates microwaves, so that the heating unit is compared with a conventional fixing device using a halogen lamp or the like. Therefore, power saving can be achieved. In addition, the warm-up time can be shortened compared to the heat generation waiting time of a conventional halogen lamp or the like.
Moreover, since the microwave absorber is fixedly supported in the vicinity of the nip portion inside the rotating body of the heating unit, the microwave radiated from the microwave radiating unit is always absorbed and heat is efficiently generated. . As a result, compared with the fixing device described in Patent Document 2, the heating efficiency of the heating unit itself can be increased.
Further, since the rotating body of the heating unit is pressed against the pressing unit to form a nip portion, the recording paper introduced into the nip portion can be sufficiently fixed by heating and pressing.

  If the above rotating body is a cylindrical roller body, the cost and durability of the heating unit are good. Further, if the above rotating body is an endless belt-like fixing film, the thermal conductivity from the microwave absorber of the heating section can be enhanced.

The best mode for carrying out the present invention will be described below with reference to the drawings.
FIG. 1 is a schematic longitudinal sectional view showing an example of an image forming apparatus provided with the fixing device according to the first embodiment, and FIG. 2 is a schematic longitudinal sectional view schematically showing an identification fixing device.

The image forming apparatus 1 shown in FIG. 1 is illustrated by taking a printer having an electrophotographic recording unit as an example. However, the image forming apparatus 1 is not limited to this, and is not limited to this. A so-called multifunction machine or the like may also be used. In addition, the fixing device according to the present embodiment can be applied to an image forming apparatus including a recording unit of various color recording methods and the like without being limited to a monochrome electrophotographic recording unit.
In the figure, the apparatus main body 10 of the image forming apparatus 1 includes a recording paper supply unit 2 that supplies recording paper (paper), an electrophotographic image recording unit 3, and a recording paper discharge unit 4 after recording. It is configured to be stacked in the height direction in this order.

The recording paper supply unit 2 includes a detachable recording paper supply cassette 20 that can store a large number of recording papers in a stacked state, a separation roller 21 installed at the front end of the recording paper supply cassette 20, and the separation roller 21. And a separation pad 22 that elastically contacts the peripheral surface.
In the figure, reference numeral 23 denotes a push-up plate that pushes up the accumulated recording paper. The push-up plate 23 is always given an upward elasticity by a compression coil spring or the like.
Further, it is possible to construct a multi-stage cassette by stacking similar cassettes under the recording paper supply cassette 20 or to install an optional cassette (not shown). Further, a retard roller can be used in place of the separation pad 22.
In the recording paper supply unit 2, the front end of the recording paper deposited on the push-up plate 23 is pressed against the circumferential surface of the separation roller 21. When the separation roller 21 rotates, the stacked recording sheets are separated one by one from the uppermost layer by the cooperative action of the separation roller 21 and the separation pad 22 and are fed out toward the recording sheet conveyance path 8 to be described later. Is done.

  The image recording unit 3 is arranged around the photosensitive drum 30 with a plus (or minus) charger 31, an exposure device 32 composed of LEDs, a developing device 33, a transfer roller 34 and a cleaning device 35 in this order. And a fixing device 5 to be described later. The photosensitive drum 30, the charger 31 and the cleaning device 35 are unitized as a drum unit, and the developing device 33 is unitized as a developing device unit, and each unit is individually or coupled to the apparatus main body 10. It is detachably attached. These units can be inserted / removed in the direction perpendicular to the paper surface in FIG. 1, can be taken out above the apparatus main body 10, or can be inserted / removed from the other side of the apparatus main body 10. There is also a case.

  On the downstream side of the fixing device 5, a switching gate 41, a discharge roller pair 42 and a discharge tray 40 are provided, and the recording paper discharge unit 4 is configured by these. A registration roller pair 7 is installed in the vicinity of the upstream side of the process section. The recording sheets separated and fed one by one from the recording sheet supply cassette 20 as described above are registered by the registration roller pair 7 and introduced into the nip portion between the photosensitive drum 30 and the transfer roller 34. The The surface of the photosensitive drum 30 is rotated positively (or minus) by the charger 31 while rotating in the direction of the arrow in FIG. 1, and an optical image based on the image information is transferred to the photosensitive drum 30 by the exposure device 32. The surface is irradiated and an electrostatic latent image is formed on the surface of the photosensitive drum 30. This electrostatic latent image is formed by the difference in potential generated between the light irradiated portion and the non-irradiated portion based on the characteristics of the photoconductor on the surface of the photosensitive drum 30.

The electrostatic latent image is successively developed by the developing unit 33 to be a toner image. This toner image reaches the nip portion with the transfer roller 34 as the photosensitive drum 30 rotates. The registration roller pair 7 is rotationally driven under registration control so that the recording paper is introduced into the nip portion in synchronization with the movement of the toner image on the surface of the photosensitive drum 30.
The transfer roller 34 nips and conveys the recording paper while being in contact with the photosensitive drum 30 and being rotationally driven in the direction of the arrow (with respect to the photosensitive drum 30). During this time, the toner image on the surface of the photosensitive drum 30 is transferred to the recording paper. Is transcribed. The recording sheet on which the toner image has been transferred is introduced into a fixing device 5 to be described later and fixed as a permanent image, and then the switching gate 41 is pushed up and discharged onto the discharge tray 40 through the discharge roller pair 42.
This series of recording paper transports rises substantially vertically (vertically) immediately after feeding out from the recording paper supply cassette 20, and in the discharge unit 4, the feeding direction from the recording paper supply cassette 20 is about 180 degrees. It is made along a recording paper conveyance path (hereinafter referred to as a main conveyance path) 8 that turns. With such a layout configuration, the entire apparatus can be made compact.

In the present embodiment, the developing unit 33 exemplifies a developing unit using a two-component developer. The developing device 33 includes a developer storage chamber for storing a developer composed of toner and a carrier in a resin-molded casing. In the storage chamber, two stirring and conveying screws 330, a supply roller 331, And a developing roller 332 to which a bias is applied. These mechanism units 330, 331, and 332 in the storage chamber are connected to a drive transmission mechanism (not shown) in the apparatus main body 10 and can be driven to rotate when the developing device 33 is attached to a predetermined portion in the apparatus main body 10. State. The developing roller 332 is electrically connected to a bias application power source (not shown).
A toner tank 37 and a toner hopper 39 are installed at a position apart from the developer storage chamber. When the toner concentration in the developer storage chamber decreases, the toner is developed from the toner hopper 39 via a screw conveyor (pipe screw) 390. It is replenished in the medicine reservoir. The toner tank 37 is integrated with a waste toner tank 38 and is configured as a toner cartridge 36 that is detachably attached to the apparatus main body 10. The transfer residual toner removed from the surface of the photosensitive drum 30 by the cleaning device 35 is collected in a waste toner tank 38 via a screw 333.
The developing device 33 is not limited to a method using a two-component developer, and a one-component method and other methods can also be adopted. Alternatively, the developing unit 33 and the toner cartridge 36 may be integrated into a developing unit.

The illustrated image forming apparatus 1 further includes a double-sided recording function. A reverse recording paper transport path (hereinafter referred to as a reverse transport path) 9 that circulates and joins the main transport path 8 on the upstream side of the registration roller pair 7 from the attachment position of the switching gate 41 of the main transport path 8 is provided. Is formed.
Two pairs of conveyance rollers 90 and 91 are provided along the reverse conveyance path 9. When the trailing edge of the recording sheet conveyed along the main conveyance path 8 and subjected to single-sided recording reaches the discharge roller pair 42, it is supplied to the reverse conveyance path 9 by the reverse rotation of the discharge roller pair 42. The recording paper supplied to the reverse conveyance path 9 is continuously conveyed along the reverse conveyance path 9 by the conveyance roller pairs 90 and 91, joins the main conveyance path 8, and reaches the registration roller pair 7. Thereafter, the toner is introduced again into the nip portion between the photosensitive drum 30 and the transfer roller 34, and recording on the back surface is performed. The recording paper recorded on both sides is discharged onto the discharge tray 40 along the main conveyance path 8 as described above.

The image forming apparatus 1 shown in the figure further includes a manual recording paper supply unit 11. In the manual paper supply unit 11, a recording paper is set on a manual feed tray 110 that is openable and closable on the side surface of the apparatus body 10, and the recording paper is fed by the action of the separation roller 111 and the separation pad 112. These are separated and supplied into the apparatus main body 10. The separated and supplied recording paper passes through the manual recording paper transport path 113 and joins the main transport path 8 and is introduced into the nip portion between the photosensitive drum 30 and the transfer roller 34 by the registration roller pair 7.
In the figure, reference numeral 13 denotes a jam access cover that is opened and closed when a paper jam (recording paper jam) occurs in the main transport path 8 and the reverse transport path 9.

Next, the fixing device according to the first embodiment will be described with reference to FIG.
The fixing device 5 according to the present embodiment is installed on the downstream side in the recording paper conveyance direction of the process unit (see FIG. 1) including the above-described photosensitive drum 30 and the like, and presses each other into a resin-molded fixing device housing 51. A heat roller 52 and a press roller 56 that are in contact with each other are provided.
An upstream opening 510 for receiving a recording sheet conveyed along the main conveying path 8 is formed on the upstream side (lower side of the sheet) of the fixing device housing 51 in the conveying direction of the recording sheet. A downstream opening 511 for discharging the recording paper on which the toner image is fixed toward the discharge unit 4 is formed on the downstream side (upper side of the paper surface) of the fixing device housing 51 in the recording paper conveyance direction.
As shown in FIG. 1, the fixing device 5 in the state of being installed in the apparatus main body 10 has a nip portion 50 formed along the main conveyance path 8 formed by the heat roller 52 and the press roller 56 being pressed against each other. Are arranged as follows.

In the fixing device housing 51, a separation claw 513 for separating the recording paper to be conveyed from the heat roller 52 and a guide rib 512 for guiding the conveyance of the recording paper are in the roller axis direction (longitudinal direction, direction orthogonal to the recording paper conveyance direction). ) Are formed at a plurality of locations along the line.
The peeling claw 513 is configured to be swingable with its base end supported, and is elastically applied by a torsion spring or the like so that the tip of the peeling claw 513 is always in contact with the outer surface of the heat roller 52.
In the fixing device housing 51, a temperature sensor 514 is provided in contact with a vicinity of an end portion in a longitudinal direction of a microwave absorber 54 described later.

The heat roller 52 includes a microwave oscillation unit 53, a microwave absorber 54, and a cylindrical roller body 55 constituting a rotating body, and constitutes a heating unit.
The microwave oscillation unit 53 includes a microwave oscillator 530 that oscillates a microwave, an amplifier 531 that amplifies the oscillated microwave, an isolator 532 that absorbs the microwave that returns to the microwave oscillator 530, and a microwave radiation that radiates the microwave. A portion 533 is provided. In addition, a waveguide 534 that guides the microwave oscillated from the microwave oscillator 530 and a microwave concentration unit 535 that reflects the microwave radiated from the microwave radiation unit 533 and concentrates the microwave toward the microwave absorber 54. I have.

In this embodiment, the microwave oscillator 530 uses a magnetron that oscillates a microwave having a frequency of about 2.45 GHz, but may be another oscillator that can oscillate a microwave such as a klystron or a gyrotron.
Further, the frequency of the microwave is not limited to the above, and may be about 1 GHz to 30 GHz.

The microwave radiating portion 533 is formed in an elongated shape along the longitudinal direction over the entire region of the cylindrical roller body 55 through which at least the recording paper passes.
The microwave concentrating portion 535 is made of a metal material such as aluminum, copper, or stainless steel that reflects microwaves, and is formed in a substantially U shape in a longitudinal cross-sectional view. The microwave concentrating portion 535 is long like the microwave radiating portion 533. Is formed. Moreover, the microwave absorber 54 mentioned later is being fixed so that the U-shaped open side may be fitted.

The microwave absorber 54 includes a hollow cylinder 540 that is sealed at both ends and a heating medium 541 sealed in the hollow cylinder 540, and is similar to the microwave radiating unit 533. It is formed in a long shape.
The hollow cylinder 540 is made of a material having a small dielectric loss coefficient that transmits the microwave radiated from the microwave radiating portion 533, and examples thereof include ceramics, glass, and resin. Further, the hollow cylindrical body 540 is formed in a substantially rectangular shape in a longitudinal cross-sectional view, and the surface on the press roller 56 side is curved to match the inner peripheral surface of the cylindrical roller body 55. Further, at least the surface thereof is formed to be larger than the nip width of the nip portion 50 in the recording paper conveyance direction. Thereby, the heat generation efficiency of the microwave absorber 54 can be improved. That is, compared with the case where the microwave absorber 54 is formed in a cylindrical shape along the inner peripheral surface of the cylindrical roller body 55, the time for uniformly generating heat is short, and thus the heat generation efficiency can be increased.

The heating medium 541 is composed of a medium made of a dielectric material having a large dielectric loss coefficient that absorbs the microwave transmitted through the hollow cylindrical body 540, and is a liquid such as silicon oil, alcohol, or water having a high boiling point sealed with high pressure. Is mentioned. Alternatively, it may be a solid such as a resin having a high melting point and a large dielectric loss coefficient. In this case, you may make it comprise the microwave absorber 54 with this solid, without enclosing in the hollow cylinder 540. FIG.
The boiling point and melting point are set according to the fixing temperature for fixing the toner image formed on the recording paper, and are set to about a normal fixing temperature of about 140 ° to 180 °, for example.

The microwave radiation portion 533, the microwave concentration portion 535, and the microwave absorber 54 described above are held by the fixing device housing 51 with their both ends fixed. The radiation direction of the microwave radiated from the microwave radiation portion 533 is set so as to go to the nip portion 50 with the press roller 56 to be described later, and the microwave absorber 54 is located downstream of the radiation direction. It is installed in the vicinity of the nip portion 50.
The shape of the microwave absorber 54 and the output of the microwave oscillator 530 are appropriately set so that the microwave absorber 54 generates heat uniformly by the microwave radiated from the microwave radiating unit 533.

The cylindrical roller body 55 includes a cylinder 550 made of aluminum or the like having good heat conductivity that constitutes the heat transfer layer, and a coating layer (release layer) 551 formed on the inner circumferential side in the longitudinal direction of the cylinder 550. And. Further, both end portions of the cylindrical roller body 55 are rotatably supported by bearings (not shown) formed in the fixing device housing 51.
A gear (not shown) is attached to one end of the cylinder 550 and is connected to a drive transmission mechanism (not shown) in the apparatus main body 10 to rotate the cylindrical roller body 55.
The coating layer 551 is for reducing adhesion of toner or paper powder, and is made of, for example, a tetrafluoroethylene / perfluoroalkylvinyl copolymer or the like and formed by painting or the like.
The length along the longitudinal direction of the coating layer 551 is at least the length (width) of the recording paper conveyed through the nip portion 50 between the heat roller 52 and the press roller 56 brought into contact with each other.
In the example shown in the figure, the cylindrical roller body 55 is shown to be relatively thick. Is configured to be conducted efficiently.

The cylindrical roller body 55 includes a microwave radiation portion 533, a microwave concentration portion 535, and a microwave absorber 54 that are fixed in the fixing device housing 51 described above. When the cylindrical roller body 55 is driven to rotate, the surface on the press roller 56 side (hereinafter referred to as a curved surface) of the microwave absorber 54 and the inner peripheral surface of the cylindrical roller body 55 are rubbed with each other. The cylindrical roller body 55 rotates. Alternatively, they may be installed such that a slight clearance is formed between the curved surface of the microwave absorber 54 and the inner peripheral surface of the cylindrical roller body 55.
When the curved surface of the microwave absorber 54 and the inner peripheral surface of the cylindrical roller body 55 are rubbed with each other, the hollow cylindrical body 540 has a low coefficient of friction and is disposed on the inner peripheral surface of the cylindrical roller body 55. A lubricant or the like may be applied.

The press roller 56 includes a press roller shaft 560 formed of a metal material such as a steel material, a cylindrical elastic member 561 externally mounted on the press roller shaft 560, and a release layer 562, and constitutes a pressure unit. To do.
The cylindrical elastic member 561 is made of a rubber body such as silicone or urethane or a sponge body, and is fixed to the press roller shaft 560 with an adhesive or the like.
On the outer peripheral surface of the cylindrical elastic member 561, a release layer made of, for example, a fluororesin tube such as tetrafluoroethylene / perfluoroalkylvinyl copolymer or the like for improving the releasability of recording paper, toner or paper powder. 562 is provided.
In addition, as a metal material applied to a press roller axis | shaft, it is good also as what gave nickel plating to steel materials, such as SUM24L and S20C. The thickness of the fluororesin tube 562 is preferably about 30 to 50 μm.

Both ends of the press roller shaft 560 are rotatably supported by the bearing body 563. The bearing body 563 is slidably provided with respect to the fixing device housing 51 and is pressed toward the heat roller 52 by the elasticity of a roller pressing member 564 made of a coil spring or the like fixed to the fixing device housing 51. Yes.
By this roller pressing member 564, the press roller 56 is pressed against the heat roller 52, and the nip portion 50 is formed.

Note that the roller pressing member 564 has a base end portion fixedly supported by a metal chassis (not shown) fixed in the fixing device housing 51.
Further, the roller pressing member 564 is not limited to a coil spring, and may be any pressing member that can press the press roller 56 against the heat roller 52.
Further, although not shown, the fixing device 5 includes a nip releasing mechanism that releases the nip state (contact state) between the heat roller 52 and the press roller 56. Further, a cleaning roller or a cleaning blade for removing paper dust and toner adhering to the surface of the heat roller 52 is provided.

In the fixing device 5 configured as described above, the microwave oscillation unit 53 is driven to heat the microwave absorber 54 and rotate the cylindrical roller body 55. The rotating cylindrical roller body 55 is heated by heat conduction from the microwave absorber 54 that has been irradiated with microwaves and heated. Further, when the cylindrical roller body 55 is driven to rotate, a press roller 56 to be described later is driven to rotate so that the recording paper introduced into the nip portion 50 is nipped and conveyed while the recording paper passes through the nip portion 50. The transferred toner image is fixed by heating and pressing.
Further, based on the detection signal from the temperature sensor 514, energization (ON / OFF) of the microwave oscillator 530 is controlled so that the microwave absorber 54 is maintained at a predetermined temperature, and the cylindrical roller body 55 is controlled. The surface temperature is maintained at a predetermined fixing temperature.

As described above, according to the fixing device 5 according to the present embodiment, the heat roller 52 configuring the heating unit is configured to heat the microwave absorber 54 by the microwave radiated from the microwave radiating unit 533. Compared with a fixing device using a conventional halogen lamp or the like, power can be saved. In addition, the warm-up time can be shortened compared to the heat generation waiting time of a conventional halogen lamp or the like.
Further, since the microwave absorber 54 is fixedly supported in the vicinity of the nip portion 50 inside the cylindrical roller body 55, the microwave radiated from the microwave radiating portion 533 is always absorbed and efficiently. Fever. As a result, the heat generation efficiency of the heat roller 52 itself can be increased as compared with the fixing device described in Patent Document 2.

Further, since the toner is not melted directly by the microwave but is melted by heating the cylindrical roller body 55 by the heat conduction from the microwave absorber 54, a general-purpose inexpensive toner can be used. .
Further, since the cylindrical roller body 55 is pressed against the press roller 56 to form the nip portion 50, the recording paper introduced into the nip portion 50 can be sufficiently fixed by heating and pressing.
Furthermore, in the present embodiment, since the microwave concentration unit 535 for concentrating the microwave radiated from the microwave radiation unit 533 toward the microwave absorber 54 is provided, the microwave absorber 54 is made efficient. Can be heated. Further, the scattering of the microwaves radiated from the microwave radiating unit 533 into the cylindrical roller body 55 or the inside of the fixing device housing 51 can be reduced.

Next, another embodiment according to the present invention will be described with reference to the drawings.
FIG. 3 is a schematic longitudinal sectional view schematically showing the fixing device according to the second embodiment.
The difference from the first embodiment is mainly the configuration of the heating unit, and the other configurations are the same as those of the first embodiment, so the same reference numerals are given and the description is omitted.

The film heating unit 62 constituting the heating unit of the fixing device 6 according to the present embodiment includes a microwave oscillation unit 53 and a microwave absorber 54 similar to those of the first embodiment, a fixing film 65 constituting a rotating body, and the like. A driving roller 63 and a driven roller 64 are provided.
The fixing device housing 61 includes an upstream opening 610, a downstream opening 611, a guide rib 612, a peeling claw 613, and a temperature sensor 614 similar to those in the first embodiment. The peeling claw 613 is a nip portion of the fixing film 65. 60 is in contact with the downstream vicinity surface.

The fixing film 65 has a layer structure made of a heat-resistant member formed in an endless belt shape, and a metal film as a heat transfer layer is bonded to the back side of the polyimide film serving as a base material, and is separated to the front side of the polyimide film. Coating is applied as a mold layer. The film thickness of the fixing film 65 is about several tens μm to several hundreds μm. The heat transfer layer and the release layer may be formed of the same material as in the first embodiment.
The fixing film 65 is supported at three points of a driving roller 63, a driven roller 64 that also serves as a tension roller, and a microwave absorber 54. When the driving roller 63 is driven to rotate, the curved surface of the microwave absorber 54. Rotate while rubbing against each other. With the rotation of the fixing film 65, the press roller 56 is driven to rotate through the nip portion 60.

In the fixing device 6, as in the first embodiment, the microwave radiated from the microwave radiating unit 533 is absorbed by the microwave absorber 54 to generate heat, and by heat conduction from the microwave absorber 54, The fixing film 65 is heated. The heated fixing film 65 heats the toner.
According to such a fixing device 6, as in the first embodiment, it is possible to save power and shorten the warm-up time, and to increase the heat generation efficiency of the film heating unit 62 itself.
It should be noted that the drive roller 63, the driven roller 64, and the microwave absorber 54 may be provided with restriction members that restrict the meandering of the fixing film 65 at both ends.
Further, a lubricant or the like may be applied to the inner peripheral surface of the fixing film 65 in order to smooth the friction between the curved surface of the microwave absorber 54 and the fixing film 65.

In each of the above embodiments, the heating unit side configured by the heat roller 52 or the film heating unit 62 is driven to rotate, and the pressing unit side configured by the press roller 56 is driven to rotate. It is good also as a structure which the heating part side rotates following by the rotational drive of a part side.
Moreover, although the press roller 56 pushed toward the heating part side is illustrated as the pressurizing part, it is not limited to this, and the nip part 50 is formed by being pushed from the heating part side and elastically deformed. It is good also as a structure. Or it is good also as a pressurization part comprised by the endless belt instead of using a roller-shaped pressurization part.

1 is a schematic longitudinal sectional view illustrating an example of an image forming apparatus to which an embodiment of a fixing device according to the present invention is applied. 2 is a schematic longitudinal sectional view schematically showing an example of the fixing device. FIG. FIG. 5 is a schematic longitudinal sectional view schematically showing another embodiment of the fixing device according to the present invention.

Explanation of symbols

5,6 Fixing device 50, 60 Nip part 52 Heat roller (heating part)
54 Microwave absorber 55 Cylindrical roller body (rotating body)
56 Press roller (Pressurizing section)
533 Microwave Radiation Unit 62 Film Heating Unit (Heating Unit)
65 Fixing film (rotating body)

Claims (3)

A fixing device that fixes a toner image transferred to a recording sheet by a heating unit and a pressing unit and conveys the recording sheet,
The heating unit includes a microwave radiating unit that radiates microwaves, a microwave absorber that is heated by the microwave radiated from the microwave radiating unit, and heat conduction from the heated microwave absorber. A rotating body that is heated and pressed against each other to form a nip portion; and
The microwave absorber is formed in an elongated shape along a direction orthogonal to the recording paper conveyance direction, and is fixedly supported in the vicinity of the nip portion inside the rotating body. apparatus. In claim 1,
The fixing device according to claim 1, wherein the rotating body is a cylindrical roller body. In claim 1,
The fixing device according to claim 1, wherein the rotating body is an endless belt-shaped fixing film.

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