JP2010276760A - Fixing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing device for making a distance, from an outer peripheral surface of a first rotating body to a temperature detection member, stable. <P>SOLUTION: The fixing device includes: the first rotating body 9a; a heater 920 heating the first rotating body 9a from the inside; a pressure receiving member 940 abutting on an inner peripheral surface of the first rotating body 9a; a supporting member 960 supporting the pressure receiving member 940; a second rotating body 9b holding material to be transferred T with the pressure receiving member 940 through the first rotating body 9a, and forming a fixing nip N9; a temperature detecting member 980 detecting temperature of the outer peripheral surface of the first rotating body 9a; and a pressing member 965, which presses the first rotating body 9a in a direction going from the outside toward the inside in a radial direction to change a rotational locus of the first rotating body 9a, pressing the first rotating body 9a so that a curved surface part 967, curved to project to the outside of the first rotating body 9a than when the first rotating body 9a is not pressed, is formed to be opposed to the temperature detecting member 980. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention provides an image forming apparatus such as a copying machine, a printer, a facsimile, or a complex machine thereof, and a fixing device that melts toner constituting a toner image and fixes it on a transfer material such as paper. About.

  Conventionally, as an apparatus for forming (printing) an image on a sheet, an image forming apparatus such as a copier, a printer, a facsimile, or a complex machine of these is known. In the image forming apparatus, a charging step for charging the surface of the photosensitive drum, an exposure step for irradiating the charged photosensitive drum with laser light to form an electrostatic latent image on the surface of the photosensitive drum, and the surface of the photosensitive drum A developing process for developing the toner by attaching toner to the electrostatic latent image formed thereon, a transferring process for transferring the toner image formed from the toner attached to the surface of the photosensitive drum to the paper, and the toner transferred to the paper An image is formed on the paper by sequentially performing each of the fixing steps for fixing the image on the paper.

  Among the above steps, in the fixing step, in order to fix the toner constituting the toner image transferred onto the paper onto the paper, it is necessary to apply heat to the toner to melt the toner. Conventionally, as a fixing device that performs a fixing process, a heating roller, a pressure roller that forms a fixing nip by sandwiching a sheet on which a toner image is transferred between the heating roller, and a fixing nip from the inside of the heating roller are provided. A fixing device including a heater for heating is used.

  On the other hand, in the fixing device, instead of the heating roller, a heating rotating belt (first rotating body) that can rotate in the circumferential direction in the form of an endless belt (including an endless film), and a heating rotation that is arranged inside the heating rotating belt. A configuration is proposed in which a heating belt mechanism including a pressure receiving member that abuts on the inner peripheral surface of the belt is used, and the heating rotation belt is driven to rotate by rotation of a pressure roller that is rotationally driven (for example, , See Patent Document 1 below).

  In a fixing device using a heating belt mechanism, the surface temperature of the heating rotating belt needs to be kept within a predetermined range during the fixing process. For this reason, a configuration in which the surface temperature is controlled by measuring the surface temperature of the heating rotating belt using a non-contact temperature detecting member has been proposed (for example, see Patent Document 2 below). ). The measurement accuracy of the non-contact type temperature detection member depends on the distance from the temperature detection member to the heating rotary belt, and if the distance from the non-contact type temperature detection member to the heating rotary belt is unstable, the heating rotary belt The surface temperature cannot be measured accurately.

JP 2007-212907 A JP 2008-170643 A

  However, in the fixing device described in Patent Document 2, since the heating rotating belt is formed in an endless belt shape (including an endless film shape), there is a possibility that the rotation locus of the heating rotating belt is not stable. . When the rotation locus of the heating rotating belt is not stable, there is a problem that the distance from the non-contact type temperature detecting member to the heating rotating belt is not stable, and the surface temperature of the heating rotating belt cannot be accurately measured.

An object of the present invention is to provide a fixing device that includes a temperature detection member that detects the temperature of the outer peripheral surface of a first rotating body, and that can stabilize the distance from the outer peripheral surface of the first rotating body to the temperature detecting member. And
Another object of the present invention is to provide an image forming apparatus including the fixing device.

  The present invention is a fixing device that is provided in an image forming apparatus and melts toner constituting a toner image transferred onto a sheet-like transfer material and fixes the toner image on the transfer material. A first rotating body that is rotatable, a heater that is disposed inside the first rotating body, and that heats the first rotating body from the inside, and that is disposed within the first rotating body, the first rotating body. The pressure receiving member that contacts the inner peripheral surface of the first pressure member, a support member that is disposed inside the first rotating body and supports the pressure receiving member, and the pressure receiving member via the first rotating body. A rotatable second rotating body that sandwiches a material to form a fixing nip, and a temperature detection member that is disposed to face the outer peripheral surface of the first rotating body and detects the temperature of the outer peripheral surface of the first rotating body And arranged outside the first rotating body, and the first rotating body is arranged outside in the radial direction. A pressing member that changes the rotation trajectory of the first rotating body by pressing in the direction from the inner side to the inner side of the first rotating body so as to be more convex than the case where the first rotating body is not pressed. The present invention relates to a fixing device including a pressing member that presses the first rotating body such that a curved surface portion that is curved is formed to face the temperature detection member.

  Moreover, it is preferable that two said pressing members are arrange | positioned spaced apart in the circumferential direction of the said 1st rotary body, and the said curved surface part is formed between the said 2 pressing members.

  Moreover, it is preferable to further include a rotation determination unit that determines whether the rotation state of the first rotating body is good based on the temperature of the outer peripheral surface of the first rotating body detected by the temperature detection member.

  Moreover, it is preferable that the said pressing member consists of a driven roller which contacts the outer peripheral surface of a said 1st rotary body, and rotates according to rotation of a said 1st rotary body.

  The present invention also provides an image carrier on which an electrostatic latent image is formed on a surface, a developing unit for developing a toner image on the electrostatic latent image formed on the image carrier, and the image carrier. The present invention relates to an image forming apparatus including a transfer unit that directly or indirectly transfers a toner image to a sheet-like transfer material, and the fixing device.

The present invention can provide a fixing device that includes a temperature detection member that detects the temperature of the outer peripheral surface of the first rotating body, and that can stabilize the distance from the outer peripheral surface of the first rotating body to the temperature detecting member. .
In addition, the present invention can provide an image forming apparatus including the fixing device.

It is a left view for demonstrating arrangement | positioning of each component in the printer 1 of one Embodiment of this invention. 1 is a perspective view showing a fixing device 9 according to an embodiment of the present invention. 3 is a functional block diagram illustrating functions of a fixing device 9 according to an embodiment of the present invention. FIG. It is a figure which illustrates typically the curved surface part 967 formed of the press member 965 in this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
With reference to FIG. 1, the overall structure of a printer 1 as an embodiment of the image forming apparatus of the present invention will be described. FIG. 1 is a left side view for explaining the arrangement of components in a printer 1 according to an embodiment of the present invention.

  As shown in FIG. 1, a printer 1 as an image forming apparatus includes an apparatus main body M, and an image forming unit that forms a predetermined toner image on a sheet T as a sheet-like transfer material based on predetermined image information. And a paper supply / discharge unit that supplies the paper T to the image forming unit and discharges the paper T on which the toner image is formed.

  As shown in FIG. 1, the image forming unit includes a photosensitive drum 2 as an image carrier (photosensitive member), a charging unit 10, a laser scanner unit 4 as an exposure unit, a developing device 16, and a toner cartridge 5. A toner supply unit 6, a drum cleaning unit 11, a static eliminator 12, a transfer roller 8, and a fixing device 9.

  As shown in FIG. 1, the paper supply / discharge unit includes a paper feed cassette 52, a manual paper feed unit 64, a conveyance path L for paper T, a registration roller pair 80, and a paper discharge unit 50.

Hereinafter, each configuration of the image forming unit and the paper supply / discharge unit will be described in detail.
First, the image forming unit will be described.
In the image forming unit, charging by the charging unit 10, exposure by the laser scanner unit 4, development by the developing device 16, transfer by the transfer roller 8, removal from the surface of the photosensitive drum 2 in order from the upstream side to the downstream side. Charge removal by the electric device 12 and cleaning by the drum cleaning unit 11 are performed, and then fixing by the fixing device 9 is performed.

  The photosensitive drum 2 is made of a cylindrical member and functions as a photosensitive member or an image carrier. The photosensitive drum 2 is disposed so as to be rotatable in the direction of an arrow about an axis extending in a direction orthogonal to the conveyance direction of the paper T in the conveyance path L. An electrostatic latent image is formed on the surface of the photosensitive drum 2.

  The charging unit 10 is disposed above the photosensitive drum 2 so as to face the surface of the photosensitive drum 2. The charging unit 10 uniformly charges the surface of the photosensitive drum 2 to be negative (minus polarity) or positive (plus polarity).

  The laser scanner unit 4 functions as an exposure unit and is spaced apart upward from the surface of the photosensitive drum 2. The laser scanner unit 4 includes a laser light source (not shown), a polygon mirror, a polygon mirror driving motor, and the like.

  The laser scanner unit 4 scans and exposes the surface of the photosensitive drum 2 based on image information output from an external device such as a PC (personal computer). By performing scanning exposure by the laser scanner unit 4, electric charges charged on the surface of the photosensitive drum 2 are removed. As a result, an electrostatic latent image is formed on the surface of the photosensitive drum 2.

  The developing device 16 is provided in front of the photosensitive drum 2 (on the right side in FIG. 1) corresponding to the photosensitive drum 2, and is disposed to face the surface of the photosensitive drum 2. The developing device 16 attaches a single color (usually black) toner to the electrostatic latent image formed on the photosensitive drum 2 to develop a single color toner image (forms a toner image on the surface of the photosensitive drum 2). To do). The developing device 16 includes a developing roller 17 that can be disposed opposite to the surface of the photosensitive drum 2, a stirring roller 18 for stirring the toner, and the like.

  The toner cartridge 5 is provided corresponding to the developing device 16 and stores toner supplied to the developing device 16.

  The toner supply unit 6 is provided corresponding to the toner cartridge 5 and the developing device 16, and supplies the toner contained in the toner cartridge 5 to the developing device 16.

  The transfer roller 8 transfers the toner image developed on the surface of the photosensitive drum 2 to the paper T. A transfer bias for transferring the toner image developed on the photosensitive drum 2 to the paper T is applied to the transfer roller 8 by a voltage application unit (not shown).

  The transfer roller 8 is brought into contact with and separated from the photosensitive drum 2. Specifically, the transfer roller 8 is configured to be movable between a contact position where the transfer roller 8 is in contact with the photosensitive drum 2 and a spaced position where the transfer roller 8 is separated from the photosensitive drum 2. Specifically, the transfer roller 8 is moved to the contact position when the toner image developed on the photosensitive drum 2 is transferred to the paper T, and is moved to the separation position in other cases.

  A sheet T conveyed on the conveyance path L is sandwiched between the photosensitive drum 2 and the transfer roller 8. The sandwiched paper T is pressed against the surface of the photosensitive drum 2. A transfer nip N is formed between the photosensitive drum 2 and the transfer roller 8. In the transfer nip N, the toner image developed on the photosensitive drum 2 is transferred onto the paper T.

  The static eliminator 12 is disposed to face the surface of the photosensitive drum 2. The static eliminator 12 irradiates the surface of the photosensitive drum 2 with light, thereby neutralizing the surface of the photosensitive drum 2 after the transfer is performed (removing the electric charge).

  The drum cleaning unit 11 is disposed to face the surface of the photosensitive drum 2. The drum cleaning unit 11 removes toner and deposits remaining on the surface of the photosensitive drum 2, and transports the removed toner to a predetermined recovery mechanism for recovery.

The fixing device 9 melts the toner constituting the toner image transferred onto the paper T and fixes it on the paper T. The fixing device 9 includes a heating rotating belt 9a as a first rotating body heated by a heater 920 (described later), and a pressure roller 9b as a second rotating body pressed against the heating rotating belt 9a. The heating rotating belt 9a and the pressure roller 9b convey the paper T on which the toner image is transferred so as to be sandwiched. When the paper T is conveyed so as to be sandwiched between the heating rotating belt 9a and the pressure roller 9b, the toner transferred onto the paper T is melted and fixed on the paper T.
Details of the configuration of the fixing device 9 will be described later.

Next, the paper supply / discharge unit will be described.
As shown in FIG. 1, in the lower part of the apparatus main body M, a single paper feed cassette 52 that stores paper T is disposed. The paper feed cassette 52 is configured to be drawable in the horizontal direction from the front side (right side in FIG. 1) of the apparatus main body M. In the paper feed cassette 52, a placement plate 60 on which the paper T is placed is disposed. In the paper feed cassette 52, the paper T is stored in a state of being stacked on the placement plate 60. The paper T placed on the placement plate 60 is sent out to the transport path L by the cassette paper feed unit 51 arranged at the paper feed side end of the paper feed cassette 52 (the right end in FIG. 1). The cassette paper feed unit 51 includes a double feed prevention mechanism including a forward feed roller 61 for taking out the paper T on the placement plate 60 and a paper feed roller pair 63 for feeding the paper T to the transport path L one by one. Prepare.

  A manual paper feed unit 64 is provided on the right side surface (right side in FIG. 1) of the apparatus main body M. The manual paper feed unit 64 is provided mainly for supplying the apparatus main body M with a paper T of a size and type different from the paper T set in the paper feed cassette 52. The manual paper feed unit 64 includes a manual feed tray 65 that forms a part of the apparatus main body M in the closed state, and a paper feed roller 66. The lower end of the manual feed tray 65 is attached to the vicinity of the paper feed roller 66 so as to be rotatable (openable and closable). The paper T is placed on the open manual feed tray 65. The manual paper feed unit 64 feeds the paper T placed on the open manual feed tray 65 to the manual feed path La.

  A paper discharge unit 50 is provided on the upper side of the apparatus main body M. The paper discharge unit 50 discharges the paper T to the outside of the apparatus main body M by the third roller pair 53. Details of the paper discharge unit 50 will be described later.

  The conveyance path L for conveying the paper T is a first conveyance path L1 from the cassette paper feeding unit 51 to the transfer roller 8, a second conveyance path L2 from the transfer roller 8 to the fixing device 9, and a discharge from the fixing device 9. A third conveyance path L3 to the section 50, a manual conveyance path La that joins the paper supplied from the manual sheet feeding unit 64 to the first conveyance path L1, and a third conveyance path L3 from the upstream side to the downstream side. And a return transport path Lb that reverses the paper and returns it to the first transport path L1.

Moreover, the 1st junction part P1 and the 2nd junction part P2 are provided in the middle of the 1st conveyance path L1. A first branch portion Q1 is provided in the middle of the third transport path L3.
The first joining part P1 is a joining part where the manual feed path La joins the first transport path L1. The second junction P2 is a junction where the return conveyance path Lb merges with the first conveyance path L1.
The first branch portion Q1 is a branch portion where the return transport path Lb branches from the third transport path L3, and includes a first roller pair 54a and a second roller pair 54b. One roller of the first roller pair 54a and one roller of the second roller pair 54b are combined.

  In the middle of the first transport path L1 (specifically, between the second junction P2 and the transfer roller 8), a sensor for detecting the paper T, skew correction (slanting paper feeding) of the paper T, and toner A registration roller pair 80 is arranged for matching the timing with the image. The sensor is disposed immediately before (on the upstream side) the registration roller pair 80 in the transport direction of the paper T. The registration roller pair 80 conveys the paper T by performing the above-described correction and timing adjustment based on detection signal information from the sensor.

The return conveyance path Lb is a conveyance path that is provided so that the opposite surface (non-printing surface) to the surface that has already been printed faces the photosensitive drum 2 when performing duplex printing on the paper T.
According to the return conveyance path Lb, the sheet T conveyed from the first branching section Q1 to the paper discharge section 50 side by the first roller pair 54a is reversed and returned to the first conveyance path L1 by the second roller pair 54b. , And can be conveyed to the upstream side of the registration roller pair 80 disposed on the upstream side of the transfer roller 8. A predetermined toner image is transferred onto the non-printing surface by the photosensitive drum 2 on the paper T that has been turned upside down by the return conveyance path Lb.

  A paper discharge unit 50 is formed at the end of the third transport path L3. The paper discharge unit 50 is disposed on the upper side of the apparatus main body M. The paper discharge unit 50 opens toward the right side surface of the apparatus main body M (the right side in FIG. 1, the manual paper feed unit 64 side). The paper discharge unit 50 discharges the paper T conveyed through the conveyance path L3 to the outside of the apparatus main body M by the third roller pair 53.

On the opening side of the paper discharge unit 50, a paper discharge stacking unit M1 is formed. The paper discharge stacking unit M1 is formed on the upper surface (outer surface) of the apparatus main body M. The paper discharge stacking unit M1 is a portion formed by the upper surface of the apparatus main body M being depressed downward. The bottom surface of the paper discharge stacking unit M1 constitutes a part of the top surface of the apparatus main body M. In the paper discharge stacking unit M1, sheets T onto which a predetermined toner image has been transferred and discharged from the paper discharge unit 50 are stacked and stacked.
A paper detection sensor is disposed at a predetermined position on each conveyance path.

  Hereinafter, with reference to the drawings, a configuration related to a characteristic part in the printer 1 of the present embodiment will be described. FIG. 2 is a perspective view showing the fixing device 9 according to the embodiment of the present invention. FIG. 3 is a functional block diagram showing functions of the fixing device 9 according to the embodiment of the present invention. FIG. 4 is a diagram schematically illustrating the curved surface portion 967 of the pressing roller 965 in the present invention.

  As shown in FIGS. 2 and 3, the fixing device 9 of the present embodiment includes a housing 910, a heating rotating belt 9a as a first rotating body, a pressure roller 9b as a second rotating body, and a pressure receiving member. 940, a support member 960, two heaters 920 and 920, a temperature detection member 980, a plurality of pressing rollers 965 and 965 as pressing members, and a control unit 970.

  As shown in FIG. 2, the housing 910 is formed long in a direction parallel to the axial direction (second direction) D2 of the heating rotary belt 9a and the pressure roller 9b. The housing 910 is mainly composed of three members: a rectangular upper surface plate 911 and a pair of side surface plates 912 and 912 attached to the end of the upper surface plate 911 in the longitudinal direction (second direction D2). The housing 910 is formed in a substantially U shape when viewed from the conveyance direction D1 of the paper T. Each of the pair of side plates 912 and 912 is provided with a through hole 914 having a long hole shape.

  The heating rotary belt 9a is formed in a roll shape (endless belt shape) and has heat resistance. The heating rotation belt 9a is configured to be rotatable around a rotation axis extending in a second direction D2 orthogonal to the transport direction D1 of the paper T. For example, the heating rotary belt 9a is provided with an elastic layer of silicon rubber having a thickness of about 0.3 mm on the outer peripheral surface of a metal belt such as SUS (stainless steel) having a thickness of about 30 μm. By providing a release layer made of a heat-resistant film made of fluororesin such as PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer) or PTFE (polytetrafluoroethylene) having a thickness of about 30 μm on the outer peripheral surface. Composed.

As shown in FIG. 2, the pressure roller 9b is arranged so that the outer peripheral surface thereof is in contact with the outer peripheral surface of the heating rotary belt 9a. The pressure roller 9b is formed longer in the axial direction (second direction) D2 than the heating rotary belt 9a. The midpoint in the axial direction of the pressure roller 9b and the midpoint in the axial direction of the heating rotating belt 9a are substantially coincident.
The pressure roller 9b is configured to be rotatable about a rotation axis (second direction D2) parallel to the axis of the heating rotary belt 9a. More specifically, the pressure roller 9b is provided with an elastic layer made of silicon rubber or the like having a thickness of about 5.5 mm on the outer peripheral surface of a core metal such as aluminum or iron having a diameter of about 14 mm. Is provided with a release layer made of a fluororesin such as PFA or PTFE having a thickness of about 50 μm.

Further, as shown in FIG. 2, a roller shaft 931 serving as a rotation shaft protrudes from both end portions in the axial direction (second direction D2) of the pressure roller 9b. The roller shaft 931 is rotatably supported by a case of the apparatus main body M in the printer 1 and other members.
A pressure roller driving unit 932 (see FIG. 3) such as an electric motor as a second rotating body driving unit for rotating the pressure roller 9b is directly connected to the roller shaft 931 of the pressure roller 9b. The pressure roller drive unit 932 drives the pressure roller 9b to rotate at a predetermined speed, and the heating rotating belt 9a that contacts the outer peripheral surface of the pressure roller 9b rotates as the pressure roller 9b rotates. Is done. As a result, a fixing nip N9 is formed between the pressure roller 9b and the heating rotary belt 9a to sandwich the paper T on which the toner image is transferred.

  As shown in FIG. 3, the two heaters 920 and 920 heat the fixing nip N9 that is a contact portion between the heating rotary belt 9a and the pressure roller 9b. The heater 920 is composed of, for example, a halogen heater or a ceramic heater. Each of the two heaters 920 and 920 is installed on the downstream side (left side in FIG. 3) and the upstream side (right side in FIG. 3) in the transport direction D1 with respect to the support member 960 inside the heating rotary belt 9a. The heater 920 applies heat to the paper T that is nipped and conveyed between the heating rotary belt 9a and the pressure roller 9b via the heating rotary belt 9a. As a result, the paper T on which the toner image is transferred is conveyed to the fixing nip N9 and passed therethrough, whereby the toner TN on the paper T is melted and fixed on the paper T.

  As shown in FIG. 2, the pressure receiving member 940 is formed to extend long in the axial direction (second direction) D2 of the heating rotary belt 9a inside the heating rotary belt 9a. The pressure receiving member 940 is fixed by fixing members 950 and 950 at both ends in the longitudinal direction. Specifically, the fixing members 950 and 950 are disposed below the through holes 914 and 914 so as to straddle the inner side and the outer side of the side plates 912 and 912 located at both ends of the casing 910 in the longitudinal direction. The fixing members 950 and 950 have a convex shape when viewed from the axial direction (second direction) D2 of the heating rotary belt 9a, and are fixed to the housing 910.

  The pressure receiving member 940 is a member that forms a fixing nip N9 with the pressure roller 9b via the heating rotary belt 9a. The pressure receiving member 940 needs to have a certain strength or higher in order to receive the pressure received by the heating rotary belt 9a from the pressure roller 9b. Further, since the pressure receiving member 940 is in contact with the inner peripheral surface of the heating rotating belt 9a, it is necessary to have excellent heat capacity, heat resistance, wear resistance, and the like. In order to satisfy these necessary conditions, the pressure receiving member 940 is made of, for example, SUS (stainless steel). Note that the pressure receiving member 940 can be made of resin as long as the above conditions are satisfied.

  A specific configuration of the pressure receiving member 940 will be described. As shown in FIG. 3, the pressure receiving member 940 includes a slidable contact flat plate portion 941 that is in contact with the inner peripheral surface of the heating rotary belt 9 a and two side plate portions that extend perpendicular to the slidable flat plate portion 941. 942 and 942, and two inclined plate portions 943 that connect these two side plate portions 942 and 942 and the sliding contact flat plate portion 941. The pressure receiving member 940 has a C-shape that is open toward the radial center of the heating rotary belt 9a in the cross section in the rotation axis direction (second direction) D2 of the heating rotary belt 9a. The pressure receiving member 940 is made of, for example, SUS (stainless steel) having a thickness of about 0.2 mm. Since the pressure receiving member 940 has the two inclined plate portions 943 and 943 on both sides of the sliding contact flat plate portion 941, sliding of the heating rotating belt 9a with respect to the pressure receiving member 940 becomes smooth.

  As shown in FIG. 3, the support member 960 is disposed inside the heating rotating belt 9a in order to receive and support the pressure received by the pressure receiving member 940 from the pressure roller 9b, that is, to reinforce the pressure receiving member 940. Is done. The support member 960 has a substantially T shape in the cross section in the rotation axis direction (second direction) D2 of the heating rotary belt 9a. Specifically, the support member 960 has a lower end plate portion 960 </ b> A that is abutted against the sliding contact flat plate portion 941 of the pressure receiving member 940, with the heat insulating member 962 interposed therebetween, and a rising that extends toward the radial center of the heating rotary belt 9 a. And a plate portion 960B. The rising plate portion 960B has a height at which the free end is close to the inner peripheral surface of the heating rotary belt 9a.

As shown in FIGS. 2 and 3, the support member 960 is fixed by inserting both end portions in the longitudinal direction of the lower end plate portion 960 </ b> A into the groove portions 951 of the fixing members 950 and 950.
Due to the presence of the support member 960 as described above, the pressure (fixing pressure) at the fixing nip N9 is stabilized, and it is possible to apply a strong pressure to the paper T passing through the fixing nip N9, thereby preventing fixing failure.

  The support member 960 is made of SUS (stainless steel) having a thickness of about 3 mm. The heat insulating member 962 is made of a heat-resistant silicon sponge having a thickness of about 2 mm, a silicon fiber processed cloth, glass wool, or the like, and suppresses heat transfer from the pressure receiving member 940. Further, the entire surface of the lower end plate portion 960 </ b> A of the support member 960 and both surfaces of the rising plate portion 960 </ b> B are covered with the reflection member 963. The reflecting member 963 is made of aluminum or a gold film having a thickness of about 0.5 mm, and reflects the radiant heat so that the radiant heat of the heater 920 is not converted into light heat.

  As shown in FIG. 3, the temperature detection member 980 is disposed to face the outer peripheral surface of the heating rotary belt 9 a and detects the temperature of the outer peripheral surface of the heating rotary belt 9 a without contacting the outer peripheral surface of the heating rotary belt 9 a. To do. The temperature detection member 980 is disposed so as to face the upper surface of the free end of the rising plate portion 960B of the support member 960 with the heating rotating belt 9a interposed therebetween. The temperature detection member 980 is composed of, for example, a thermistor.

  As shown in FIGS. 2 and 3, the plurality of pressing rollers 965 are disposed outside the heating rotary belt 9a and press the heating rotary belt 9a in the direction from the outside toward the inside in the radial direction. Details of the configuration in which the pressing roller 965 presses the heating rotating belt 9a will be described later.

  As shown in FIGS. 2 and 3, the plurality of pressing rollers 965 are configured to be rotatable around a rotation axis extending in parallel with the rotation axis direction (second direction) D2 of the heating rotation belt 9a. Specifically, each of the plurality of pressing rollers 965 is formed in a cylindrical roll shape, and the plurality of pressing rollers 965 are arranged such that the outer peripheral surface thereof is in contact with the outer peripheral surface of the heating rotary belt 9a. The plurality of pressing rollers 965 are rotated in accordance with the rotation of the heating rotary belt 9a when the outer peripheral surfaces thereof are in contact with the outer peripheral surface of the heating rotary belt 9a.

  As shown in FIG. 2, the plurality of pressing rollers 965 and 965 are a pair of two pressing rollers 965 and 965 that are spaced apart from each other in the circumferential direction of the heating rotating belt 9 a, and the axial direction of the heating rotating belt 9 a (Second direction) Three pairs are arranged at the center and both ends of D2.

  Of the three pairs of pressing rollers, three pressing rollers 965, 965, 965 on the downstream side (back side in FIG. 2) in the transport direction D1 and three on the upstream side (front side in FIG. 2) in the transport direction D1 The pressure rollers 965, 965, and 965 are connected by pressure roller shaft members 966 and 966, respectively. The pressure roller shaft members 966 and 966 are formed between the pair of side plates 912 and 921 of the housing 910 so as to be long in the longitudinal direction (second direction) D2 of the housing 910. Both end portions of the pressing roller shaft members 966 and 966 are rotatably supported by the pair of side plates 912 and 912 in the housing 910, respectively.

  More specifically, the rotation axis of the pressure roller shaft member 966 is configured to substantially coincide with the rotation axes of the three pressure rollers 965, 965, 965. The pressure roller shaft member 966 connects the three pressure rollers 965, 965, 965 to each other along the rotation axis, thereby connecting the three pressure rollers 965, 965, 965. As a result, the pressure roller shaft member 966 and the three pressure rollers 965, 965, 965 connected by the pressure roller shaft member 966 rotate integrally around the same rotation axis.

  Further, the diameter of the pressing roller shaft member 966 is formed smaller than the diameter of the pressing roller 965. Accordingly, the pressing roller shaft member 966 is configured not to contact the outer peripheral surface of the heating rotary belt 9a. As a result, each of the three pressing rollers 965, 965, 965 is smoothly driven by the rotation of the heating rotating belt 9a in conjunction with the pressing rollers 965, 965, 965 connected by the pressing roller shaft member 966. Rotate.

Next, regarding the arrangement of the plurality of pressing rollers 965 when viewed in the direction of the rotation axis of the heating rotating belt 9a, attention is paid to the two pressing rollers 965, 965 that are arranged apart from each other in the circumferential direction of the heating rotating belt 9a. To explain. The same applies to the description of functions and effects based on the arrangement of two pressing rollers 965 and 965, which will be described later.
As shown in FIGS. 2 and 3, the two pressing rollers 965 and 965 are arranged apart from each other in the circumferential direction of the heating rotary belt 9a.

The two pressing rollers 965 and 965 are disposed on the side where the temperature detection member 980 is disposed on the outer peripheral surface of the heating rotary belt 9a.
The two pressing rollers 965 and 965 are arranged on the outer peripheral surface of the heating rotary belt 9a on the downstream side (left side in FIG. 3) and the upstream side of the outer peripheral surface of the heating rotary belt 9a facing the temperature detection member 980, respectively. (Right side in FIG. 3) They are spaced apart from each other. Specifically, each of the two pressing rollers 965 and 965 is disposed at substantially the same distance in both directions in the circumferential direction of the heating rotary belt 9a from the outer peripheral surface of the heating rotary belt 9a facing the temperature detection member 980. The

Details of the configuration in which the pressing roller 965 presses the heating rotating belt 9a will be described.
As shown in FIG. 3, the pair of pressing rollers 965 and 965 that are separated in the circumferential direction of the heating rotary belt 9a press the heating rotary belt 9a in the direction from the outer side to the inner side in the radial direction. Change the rotation trajectory. By changing the rotation locus of the heating rotary belt 9a, a curved surface portion 967 is formed on the heating rotary belt 9a. The curved surface portion 967 is formed to face the temperature detection member 980.

  The curved surface portion 967 is formed between the two pressing rollers 965 and 965 by pressing the heating rotary belt 9a in the direction from the outer side to the inner side in the radial direction by the two pressing rollers 965 and 965. The curved surface portion 967 is formed to be curved so as to protrude outward from the heating rotary belt 9a than when the heating rotary belt 9a is not pressed. In other words, the curved surface portion 967 is configured such that a part of the curved surface of the heating rotating belt 9a is pushed out of the heating rotating belt 9a when the curved surface of the heating rotating belt 9a is pressed by the two pressing rollers 965 and 965. Formed.

For example, as shown in FIG. 4, the curved surface portion 967 has a curvature radius R1 that is smaller than a curvature radius R2 when the heating rotary belt 9a is not pressed when viewed in the axial direction of the heating rotary belt 9a. It is formed. The curved surface portion 967 having the curvature radius R1 is formed so as to protrude outward from the curved surface of the heating rotation belt 9a having the curvature radius R2 when the heating rotation belt 9a is not pressed.
Thereby, the curved surface part 967 as a stable curved surface is formed in the heating rotating belt 9a. Therefore, the position of the curved surface portion 967 in the radial direction of the heating rotary belt 9a is stabilized. The main reason is considered that the degree of freedom of the rotation locus of the heating rotary belt 9a is limited by the heating rotary belt 9a being pressed by the two pressing rollers 965 and 965.

  As shown in FIG. 3, the control unit 970 includes a rotation determination unit 971, a pressure roller drive control unit 972, a heater control unit 975, and a notification unit 973. A warning sound output unit 974 is connected to the notification unit 973. The rotation determination unit 971 receives the temperature detected by the temperature detection member 980, and determines whether the rotation state of the heating rotary belt 9a is good or not based on the input temperature. Details of the quality determination of the rotating state of the heating rotating belt 9a will be described later.

  The pressure roller drive control unit 972 stops or continues the rotation drive of the pressure roller 9b by outputting the control signal S2 to the pressure roller drive unit 932 based on the determination signal S1 output from the rotation determination unit 971. Control to do.

  The heater control unit 975 is a switch (not shown) interposed in a power supply circuit (not shown) from the power supply unit (not shown) to the heater 920 based on the determination signal S1 output from the rotation determination unit 971. The ON / OFF signal S3 is output to control the heating operation of the heating rotating belt 9a by the heater 920 (heat generation of the heater 920).

Further, the notification unit 973 outputs a control signal S4 to the warning sound output unit 974 based on the determination signal S1 output from the rotation determination unit 971 so as to emit a warning sound or not to the warning sound output unit 974. To control.
In place of the warning sound output unit 974 connected to the notification unit 973, a warning lamp output unit that lights and displays a warning, a warning display output unit that displays a warning character, or a combination of a warning sound and a lighting display or character display A composite warning output unit may be used.

Next, the operation of the printer 1 of the present embodiment will be briefly described with reference to FIG.
First, the case where one side printing of the paper T stored in the paper feed cassette 52 is described.
The paper T accommodated in the paper feed cassette 52 is sent out to the first transport path L1 by the forward feed roller 61 and the roller pair 63, and then the registration roller pair 80 through the first joining portion P1 and the first transport path L1. It is conveyed to.
In the registration roller pair 80, skew correction of the paper T and timing adjustment with the toner image are performed.

The paper T discharged from the registration roller pair 80 is introduced between the photosensitive drum 2 and the transfer roller 8 through the first conveyance path L1. A toner image is transferred onto the paper T between the photosensitive drum 2 and the transfer roller 8.
Thereafter, the paper T is discharged from between the photosensitive drum 2 and the transfer roller 8, and the fixing nip N9 between the heating rotating belt 9a and the pressure roller 9b in the fixing device 9 is passed through the second conveyance path L2. To be introduced. Then, the toner TN is melted in the fixing nip N9, and the toner TN is fixed to the paper T.

Next, the paper T is conveyed to the paper discharge unit 50 through the third conveyance path L3 by the first roller pair 54a, and is discharged from the paper discharge unit 50 to the paper discharge stacking unit M1 by the third roller pair 53.
In this way, single-sided printing of the paper T stored in the paper feed cassette 52 is completed.

  When single-sided printing is performed on the paper T placed on the manual feed tray 65, the paper T placed on the manual feed tray 65 is sent out to the manual feed path La by the paper feed roller 66, and then the first junction P1. And it is conveyed to the registration roller pair 80 via the first conveyance path L1. Subsequent operations are the same as the one-side printing operation of the paper T accommodated in the paper feed cassette 52 described above, and a description thereof will be omitted.

Next, the operation of the printer 1 when performing duplex printing will be described.
In the case of single-sided printing, as described above, the single-side printed paper T is discharged from the paper discharge unit 50 to the paper discharge stacking unit M1, and the printing operation is completed.
On the other hand, when performing double-sided printing, the paper T that has been printed on one side is reversed from the front and back of the single-sided printing via the return conveyance path Lb, and is conveyed again to the registration roller pair 80. Double-sided printing is performed on the paper T.

  More specifically, the operation is the same as the above-described single-sided printing operation until the sheet T printed on one side is discharged from the paper discharge unit 50 by the third roller pair 53. Thus, in the case of double-sided printing, the rotation of the third roller pair 53 is stopped and rotated in the opposite direction while the paper T printed on one side is held by the third roller pair 53. Thus, when the third roller pair 53 is rotated in the reverse direction, the paper T held by the third roller pair 53 moves in the reverse direction (from the paper discharge unit 50 to the first branching unit Q1) along the third conveyance path L3. Transported in the direction of heading).

  As described above, when the paper T is transported in the reverse direction on the third transport path L3, it is introduced into the second roller pair 54b (not the first roller pair 54a). The paper T then joins the second transport path L2 via the return transport path Lb and the second joining portion P2. Here, the paper T is turned upside down from the one-side printing.

  Further, the paper T is corrected or adjusted by the registration roller pair 80 and is introduced between the photosensitive drum 2 and the transfer roller 8 through the first conveyance path L1. Since the non-printing surface of the paper T passes through the return conveyance path Lb, the non-printing surface faces the photosensitive drum 2, so that the toner image is transferred to the non-printing surface, and as a result, duplex printing is performed.

  Next, the operation of the fixing device 9 which is a characteristic part of the printer 1 of the present embodiment will be described with reference to FIGS. 1 to 3.

  In the printer 1 of the present embodiment, when the printer 1 is turned on, the charging unit 10, the laser scanner unit 4, the developing device 16, the transfer roller 8, the printer control unit (not shown), and the fixing device 9 are turned on from the power supply unit. In addition, power is supplied to each of the control unit 970 and the charging unit 10, the laser scanner unit 4, the developing device 16, the transfer roller 8, and the fixing device 9 are controlled by a control signal from the printer control unit. Then, the charging process, the exposure process, the development process, the transfer process, and the fixing process are sequentially performed.

  Specifically, in the printer 1 of the present embodiment, the paper T sent out from the registration roller pair 80 passes through the first conveyance path L1 to the transfer nip N between the photosensitive drum 2 and the transfer roller 8. Be transported. When the paper T is conveyed toward the photosensitive drum 2 as described above, first, the charging unit 10 charges the entire surface of the photosensitive drum 2 in the charging process, and the laser scanner unit 4 performs laser irradiation in the exposure process. Laser light is irradiated from a light source (not shown) toward the photosensitive drum 2 to form an electrostatic latent image on the surface of the photosensitive drum 2 irradiated with the laser light.

  Next, the developing device 16 supplies the toner charged in the developing process to the photosensitive drum 2 by the developing roller 17, thereby attaching the toner to the electrostatic latent image formed on the surface of the photosensitive drum 2, Develop the toner image. Subsequently, the transfer roller 8 transfers the toner image attached to the surface of the photoconductive drum 2 onto the paper T that passes between the photoconductive drum 2 and the transfer roller 8 in the transfer process.

  Then, the paper T on which the toner image has been transferred in the transfer step is transported toward the fixing device 9 through the second transport path L2, and the fixing between the heating rotating belt 9a and the pressure roller 9b in the fixing device 9 is performed. It is conveyed to the nip N9.

  Further, by turning on a control signal output from the printer control unit to the heater 920, supply of electric power from the power source unit to the heater 920 is started, the heater 920 generates heat, and the heating rotating belt 9a by the heater 920 is heated. The heating of is started. At the same time, by turning on the control signal output from the printer control unit to the pressure roller driving unit 932, power supply from the power source unit to the pressure roller driving unit 932 is started, and the pressure roller 9b rotates. As the pressure roller 9b is driven to rotate, the heating rotary belt 9a is driven to rotate. As a result, the fixing device 9 causes the toner TN adhered to the paper T passing through the fixing nip N9 between the heating rotating belt 9a and the pressure roller 9b in the fixing process to be transferred from the heater 920 to the toner via the heating rotating belt 9a. The toner image is fixed on the paper T by being melted by the heat applied to the TN and applying pressure to the paper T by the pressure roller 9b.

Further, the pressure rollers 965 and 965 are driven to rotate as the pressure roller 9b is driven to rotate by the heating rotary belt 9a.
Here, as shown in FIG. 3, the pressing rollers 965 and 965 press the heating rotary belt 9a in the direction from the outer side to the inner side in the radial direction. The pressing rollers 965 and 965 form a curved surface portion 967 that is curved so as to protrude outward from the heating rotating belt 9a than when the heating rotating belt 9a is not pressed.

When the heating rotating belt 9a is pressed by the pressing rollers 965 and 965, the heating rotating belt 9a rotates with a stable rotation locus in a portion where the curved surface portion 967 is formed. That is, the heating rotary belt 9a rotates stably in a state where the radial position of the heating rotary belt 9a on the curved surface portion 967 is maintained substantially constant. Therefore, the position of the curved surface portion 967 in the radial direction of the heating rotary belt 9a is stabilized.
On the other hand, when the heating rotating belt 9a is not pressed by the pressing rollers 965 and 965, the heating rotating belt 9a may not rotate with a stable rotation locus due to a dent or distortion due to deformation of the heating rotating belt 9a.
In the present invention, by pressing the outer peripheral surface of the heating rotating belt 9a with two pressing rollers 965 and 965, the degree of freedom of the rotating locus of the heating rotating belt 9a is limited, and the rotating locus of the heating rotating belt 9a is reduced. Stabilize.
Thereby, in the present invention, since the position of the outer peripheral surface in the radial direction of the heating rotary belt 9a is stabilized, the temperature of the outer peripheral surface of the heating rotary belt 9a can be accurately measured.

  During the fixing operation as described above by the fixing device 9, the temperature of the outer peripheral surface of the heating rotary belt 9 a is detected by the temperature detection member 980 disposed to face the curved surface portion 967. The temperature signal S5 detected by the temperature detection member 980 is input to the rotation determination unit 971 of the control unit 970.

The rotation determination unit 971 determines pass / fail of the rotation state of the heating rotary belt 9a based on the temperature detected by the temperature detection member 980 and input to the rotation determination unit 971.
A specific example of this determination method will be briefly described.

  First, the control unit 970 starts warm-up. Specifically, the heater control unit 975 generates heat in the heater 920 and heats the heating rotary belt 9a with the radiant heat of the heater 920. Further, the pressure roller drive control unit 972 rotates the pressure roller 9b by the pressure roller drive unit 932 and rotates the heating rotating belt 9a in a driven manner.

  Then, the temperature detection member 980 detects a temperature rise value (referred to as “temperature rise value”) of the heating rotating belt 9a after a predetermined time has elapsed. Specifically, after a predetermined time (for example, 5 seconds) has elapsed since the start of warm-up, the temperature of the heating rotating belt 9a (referred to as “reference temperature”) is detected by the temperature detection member 980, and the reference temperature is detected. The temperature rise value is calculated from the value obtained by subtracting the initial temperature from.

  Next, rotation determination unit 971 determines whether or not the temperature rise value is equal to or greater than a threshold value. As a result of the comparison, when the temperature increase value after the elapse of a predetermined time (after 5 seconds) is equal to or greater than the threshold value, the rotation determination unit 971 determines that the rotation state of the heating rotating belt 9a is normal. On the other hand, when the reference temperature is less than the threshold value, the rotation determination unit 971 determines that the rotation state of the heating rotating belt 9a is abnormal.

  If the temperature rise value after the elapse of a predetermined time (after 5 seconds) is equal to or greater than the threshold value, it is recognized that the rotation state of the heating rotary belt 9a is normal, and thus the determination process ends. On the other hand, when the temperature rise value after a predetermined time has elapsed (after 5 seconds) is less than the threshold value, it is recognized that the rotation state of the heating rotary belt 9a is abnormal, and thus it is necessary to perform appropriate processing.

  A typical situation in which the rotation determination unit 971 determines that the rotation state of the heating rotary belt 9a is abnormal is that the outer peripheral surface of the heating rotary belt 9a that rotates in contact with the outer peripheral surface of the pressure roller 9b is pressurized. Slip with respect to the roller 9b, resulting in a rotation failure such that the driven rotation speed of the heating rotating belt 9a is extremely slow compared to the driving rotation speed of the pressure roller 9b or not rotating at all. It is. Therefore, when the rotation determination unit 971 determines that the rotation state of the heating rotary belt 9a is abnormal, the rotation determination unit 971 outputs a determination signal S1.

  As shown in FIG. 3, based on the determination signal S1 output from the rotation determination unit 971, the heater control unit 975 outputs a control signal S3 to turn off a switch (not shown) in the power supply circuit. Then, the supply of power from the power supply unit to the heater 920 is stopped. Thereby, the heating of the heating rotary belt 9a by the heater 920 is stopped.

  Also, as shown in FIG. 3, based on the determination signal S1 output from the rotation determination unit 971, the pressure roller drive control unit 972 outputs a control signal S2 to the pressure roller drive unit 932 to apply pressure. Control to stop the rotational drive of the roller 9b is performed.

In addition, as shown in FIG. 3, based on the determination signal S1 output from the rotation determination unit 971, the notification unit 973 outputs a control signal S4 to the warning sound output unit 974 to issue a warning sound. The sound output unit 974 is controlled.
In this way, the determination process ends.

  In the present embodiment, since the temperature of the outer peripheral surface of the heating rotary belt 9a can be measured with high accuracy, the rotation determining unit 971 can accurately determine the quality of the rotating state of the heating rotary belt 9a.

According to the fixing device 9 of the present embodiment, the following effects are exhibited.
According to the present embodiment, the temperature detection member 980 that detects the temperature of the outer peripheral surface of the heating rotary belt 9a is provided, and is disposed outside the heating rotary belt 9a, and the heating rotary belt 9a is directed from the outside toward the inside in the radial direction. The pressure roller 965 changes the rotation trajectory of the heating rotary belt 9a by pressing the heating rotary belt 9a, and the curved surface portion 967 curved so as to protrude outwardly from the heating rotary belt 9a has a higher temperature A pressing roller 965 that presses the heating rotating belt 9a is provided so as to be opposed to the detection member 980. Therefore, since the rotation locus of the heating rotary belt 9a is stabilized, the distance from the outer peripheral surface of the heating rotary belt 9a to the temperature detection member 980 can be stabilized. As a result, the temperature of the outer peripheral surface of the heating rotary belt 9a can be accurately measured with a simple configuration. Thereby, the deformation | transformation by the heat_generation | fever of the heater 920 of the heating rotating belt 9a and the ignition by the heat_generation | fever of the heater 920 of the heating rotating belt 9a can be suppressed.

  Further, according to the present embodiment, the two pressing rollers 965 and 965 are arranged apart from each other in the circumferential direction of the heating rotary belt 9a, and the curved surface portion 967 is formed between the two pressing rollers 965 and 965. The Therefore, the rotation trajectory in the curved surface portion 967 of the heating rotary belt 9a is stabilized. Therefore, the temperature of the outer peripheral surface of the heating rotary belt 9a can be accurately measured with a simple configuration.

  In addition, according to the present embodiment, the rotation determination unit 971 that determines the quality of the rotation state of the heating rotary belt 9a based on the temperature of the outer peripheral surface of the heating rotary belt 9a detected by the temperature detection member 980 is provided. Therefore, based on the temperature accurately measured by the temperature detection member 980, it is possible to accurately determine the quality of the rotation state of the heating rotary belt 9a with a simple configuration.

Further, according to the present embodiment, the pressing roller 965 includes a driven roller that contacts the outer peripheral surface of the heating rotary belt 9a and rotates following the rotation of the heating rotary belt 9a. Therefore, the pressing roller 965 rotates while pressing the heating rotary belt 9a, and thus smoothly rotates following the rotation of the heating rotary belt 9a without hindering the rotation operation of the heating rotary belt 9a. Therefore, the pressing roller 965 can stably form the curved surface portion 967 on the outer peripheral surface of the heating rotary belt 9a.
Further, since the pressing roller 965 is constituted by a driven roller, the present invention can be realized with a simple configuration.

As mentioned above, although preferred embodiment of this invention was described, this invention can be implemented with a various form, without being limited to embodiment mentioned above.
For example, in each of the above-described embodiments, the pressure roller 9b (second rotating body) is driven to rotate and the heating rotating belt 9a (first rotating body) is driven to rotate. The first rotator may be driven to rotate, and the second rotator may be driven to rotate.
Further, the pressure roller 9b is used as the second rotating body, but a pressure rotating body formed of a flexible belt formed in an endless manner can be used instead.

  Further, in the above-described embodiment, three pairs of pressing rollers each including two pressing rollers 965 and 965 are disposed in the central portion and both end portions in the axial direction (second direction) D2 of the heating rotating belt 9a. Although it was set as the structure, it is not limited to this. For example, the pressing roller 965 may be configured to be provided only at the center portion in the axial direction (second direction) D2 of the heating rotating belt 9a, only at one end portion, or at one or a plurality of locations on both end portions.

  In the above-described embodiment, the rotation determination unit 971 that determines the quality of the rotation state of the heating rotary belt 9a based on the temperature detected by the temperature detection member 980 is provided, but the configuration is not limited thereto. For example, a configuration may be provided that includes an overtemperature prevention member such as a thermal fuse that disconnects the heater 920 at a predetermined temperature based on the detection result of the temperature detection member 980.

  Further, the number and arrangement position of the heaters 920 and the number and arrangement position of the temperature detection member 980 are not particularly limited.

  The type of the image forming apparatus of the present invention is not particularly limited, and may be a copier, a printer, a facsimile, or a complex machine thereof.

  DESCRIPTION OF SYMBOLS 1 ... Printer (image forming apparatus), 2 ... Photosensitive drum (image carrier), 16 ... Developing device, 9 ... Fixing device, 9a ... Heating rotating belt (first rotating body), 9b ... Pressure roller (second rotating body), 920 ... heater, 940 ... pressure receiving member, 960 ... support member, 965 ... pressure roller (pressing member), 967 ... curved surface portion, 980 ... temperature detection member, T ... paper (transfer material), TN ... toner

Claims (5)

A fixing device provided in an image forming apparatus, for melting toner constituting a toner image transferred to a sheet-like transfer material and fixing the toner on the transfer material,
A first rotating body that is endless and rotatable in the circumferential direction;
A heater that is disposed inside the first rotating body and that heats the first rotating body from the inside;
A pressure receiving member disposed inside the first rotating body and abutting against an inner peripheral surface of the first rotating body;
A support member disposed inside the first rotating body and supporting the pressure receiving member;
A rotatable second rotating body that forms a fixing nip by sandwiching the transfer material with the pressure receiving member via the first rotating body;
A temperature detection member disposed opposite to the outer circumferential surface of the first rotating body and detecting the temperature of the outer circumferential surface of the first rotating body;
A pressing member that is disposed outside the first rotating body and changes the rotation locus of the first rotating body by pressing the first rotating body in a direction from the outer side to the inner side in the radial direction. A pressing member that presses the first rotating body such that a curved surface portion that is curved so as to protrude outward from the first rotating body is formed opposite to the temperature detecting member than when the rotating body is not pressed; A fixing device. Two pressing members are arranged apart from each other in the circumferential direction of the first rotating body,
The fixing device according to claim 1, wherein the curved surface portion is formed between the two pressing members. The fixing device according to claim 1, further comprising a rotation determination unit that determines whether the rotation state of the first rotating body is good or not based on a temperature of an outer peripheral surface of the first rotating body detected by the temperature detection member. . 4. The fixing device according to claim 1, wherein the pressing member includes a driven roller that contacts an outer peripheral surface of the first rotating body and rotates following the rotation of the first rotating body. 5. An image carrier on which an electrostatic latent image is formed on the surface;
A developing device for developing a toner image on the electrostatic latent image formed on the image carrier;
A transfer unit that directly or indirectly transfers the toner image formed on the image carrier to a sheet-like transfer material;
An image forming apparatus comprising: the fixing device according to claim 1.

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