Patent Publication Number: US-10761463-B2

Title: Heating device, fixing device, and image forming apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This patent application is based on and claims priority pursuant to 35 U.S.C. § 119(a) to Japanese Patent Application No. 2018-191714, filed on Oct. 10, 2018, in the Japan Patent Office, the entire disclosure of which is hereby incorporated by reference herein. 
     BACKGROUND 
     Technical Field 
     Exemplary aspects of the present disclosure relate to a heating device, a fixing device, and an image forming apparatus. 
     Discussion of the Background Art 
     Related-art image forming apparatuses, such as copiers, facsimile machines, printers, and multifunction peripherals (MFP) having two or more of copying, printing, scanning, facsimile, plotter, and other functions, typically form an image on a recording medium according to image data by electrophotography. 
     Such image forming apparatuses include a fixing device that fixes a toner image on a sheet serving as a recording medium under heat or a dryer that dries ink on a sheet. The fixing device and the dryer employ a laminated heater incorporating a laminated, resistive heat generator as a heater installed in the fixing device and the dryer. 
     The laminated heater is coupled to a feeding member that supplies power to the resistive heat generator. The feeding member is a resilient member such as a flat spring. As the feeding member resiliently contacts an electrode disposed in the laminated heater, conduction is established at a contact between the feeding member and the electrode, supplying power from a power supply to the resistive heat generator. 
     However, since the feeding member is under high temperatures, if the feeding member suffers from temperature increase and resultant creep deformation, the feeding member may not attain a desired resilience. In this case, contact pressure with which the feeding member contacts the electrode of the laminated heater decreases, causing faulty contact and faulty conduction. 
     The feeding member may suffer from temperature increase due to heat generation of the feeding member as the feeding member is supplied with power, other than conduction of heat from the laminated heater as described above. Hence, in order to suppress temperature increase of the feeding member further, the feeding member is requested to decrease heat generation while the feeding member is supplied with power, in addition to conduction of heat from the laminated heater. 
     SUMMARY 
     This specification describes below an improved heating device. In one embodiment, the heating device includes a heater that includes a heat generator configured to generate heat as the heat generator is supplied with power. A feeding member is configured to contact the heater and feed the power to the heat generator. The feeding member is made of a corson copper alloy. This specification further describes an improved fixing device. In one embodiment, the fixing device includes an endless belt configured to rotate and an opposed rotator configured to contact the endless belt to form a fixing nip between the endless belt and the opposed rotator, through which a recording medium bearing an image is conveyed. A laminated heater is configured to heat the endless belt. The laminated heater includes a heat generator configured to generate heat as the heat generator is supplied with power. A feeding member is configured to contact the laminated heater and feed the power to the heat generator. The feeding member is made of a corson copper alloy. 
     This specification further describes an improved image forming apparatus. In one embodiment, the image forming apparatus includes an image forming device configured to form an image and a heating device configured to heat the image borne on a recording medium. The heating device includes a heater that includes a heat generator configured to generate heat as the heat generator is supplied with power. A feeding member is configured to contact the heater and feed the power to the heat generator. The feeding member is made of a corson copper alloy. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A more complete appreciation of the embodiments and many of the attendant advantages and features thereof can be readily obtained and understood from the following detailed description with reference to the accompanying drawings, wherein: 
         FIG. 1  is a schematic cross-sectional view of an image forming apparatus according to an embodiment of the present disclosure; 
         FIG. 2  is a schematic cross-sectional view of a fixing device incorporated in the image forming apparatus depicted in  FIG. 1 ; 
         FIG. 3  is a perspective view of the fixing device depicted in  FIG. 2 ; 
         FIG. 4  is an exploded perspective view of the fixing device depicted in  FIG. 3 ; 
         FIG. 5  is a perspective view of a heating device incorporated in the fixing device depicted in  FIG. 2 ; 
         FIG. 6  is an exploded perspective view of the heating device depicted in  FIG. 5 ; 
         FIG. 7  is a plan view of a heater incorporated in the heating device depicted in  FIG. 6 ; 
         FIG. 8  is an exploded perspective view of the heater depicted in  FIG. 7 ; 
         FIG. 9  is a perspective view of the heater and a heater holder incorporated in the heating device depicted in  FIG. 6 , illustrating a connector attached to the heater and the heater holder; 
         FIG. 10  is a graph illustrating comparison in temperature change between a connector according to an embodiment of the present disclosure and a connector according to a comparative example; 
         FIG. 11  is a cross-sectional view of the connector depicted in  FIG. 9 , illustrating a method for measuring contact pressure of the connector; 
         FIG. 12  is a plan view of a heater installable in the heating device depicted in  FIG. 6 , that incorporates heat generators connected in parallel; 
         FIG. 13  is a plan view of the fixing device depicted in  FIG. 2 , illustrating one example of a layout of the fixing device; 
         FIG. 14  is a plan view of the image forming apparatus depicted in  FIG. 1 , illustrating one example of a layout inside a body of the image forming apparatus; 
         FIG. 15  is a plan view of an image forming apparatus as a variation of the image forming apparatus depicted in  FIG. 1 , illustrating another example of the layout inside the body; 
         FIG. 16  is a side view of an image forming apparatus as another variation of the image forming apparatus depicted in  FIG. 1 , illustrating yet another example of the layout inside the body; 
         FIG. 17  is a schematic cross-sectional view of a fixing device installable in the image forming apparatus depicted in  FIG. 1  as a first variation of the fixing device depicted in  FIG. 2 ; 
         FIG. 18  is a schematic cross-sectional view of a fixing device installable in the image forming apparatus depicted in  FIG. 1  as a second variation of the fixing device depicted in  FIG. 2 ; and 
         FIG. 19  is a schematic cross-sectional view of a fixing device installable in the image forming apparatus depicted in  FIG. 1  as a third variation of the fixing device depicted in  FIG. 2 . 
     
    
    
     The accompanying drawings are intended to depict embodiments of the present disclosure and should not be interpreted to limit the scope thereof. The accompanying drawings are not to be considered as drawn to scale unless explicitly noted. Also, identical or similar reference numerals designate identical or similar components throughout the several views. 
     DETAILED DESCRIPTION 
     In describing embodiments illustrated in the drawings, specific terminology is employed for the sake of clarity. However, the disclosure of this specification is not intended to be limited to the specific terminology so selected and it is to be understood that each specific element includes all technical equivalents that have a similar function, operate in a similar manner, and achieve a similar result. 
     As used herein, the singular forms “a”, “an”, and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. 
     Referring to the attached drawings, the following describes a construction of an image forming apparatus  100  according to embodiments of the present disclosure. 
     In the drawings for explaining the embodiments of the present disclosure, identical reference numerals are assigned to elements such as members and parts that have an identical function or an identical shape as long as differentiation is possible and a description of those elements is omitted once the description is provided. 
       FIG. 1  is a schematic cross-sectional view of the image forming apparatus  100  according to an embodiment of the present disclosure. The image forming apparatus  100  is a printer. Alternatively, the image forming apparatus  100  may be a copier, a facsimile machine, a multifunction peripheral (MFP) having at least two of printing, copying, facsimile, scanning, and plotter functions, or the like. 
     As illustrated in  FIG. 1 , the image forming apparatus  100  includes four image forming units  1 Y,  1 M,  1 C, and  1 Bk serving as image forming devices, respectively. The image forming units  1 Y,  1 M,  1 C, and  1 Bk are removably installed in a body  103  of the image forming apparatus  100 . The image forming units  1 Y,  1 M,  1 C, and  1 Bk have a similar construction except that the image forming units  1 Y,  1 M,  1 C, and  1 Bk contain developers in different colors, that is, yellow, magenta, cyan, and black, respectively, which correspond to color separation components for a color image. For example, each of the image forming units  1 Y,  1 M,  1 C, and  1 Bk includes a photoconductor  2 , a charger  3 , a developing device  4 , and a cleaner  5 . The photoconductor  2  is drum-shaped and serves as an image bearer. The charger  3  charges a surface of the photoconductor  2 . The developing device  4  supplies toner as a developer to the surface of the photoconductor  2  to form a toner image. The cleaner  5  cleans the surface of the photoconductor  2 . 
     The image forming apparatus  100  further includes an exposure device  6 , a sheet feeding device  7 , a transfer device  8 , a fixing device  9 , and a sheet ejection device  10 . The exposure device  6  exposes the surface of each of the photoconductors  2  and forms an electrostatic latent image thereon. The sheet feeding device  7  supplies a sheet P serving as a recording medium or a conveyed medium to the transfer device  8 . The transfer device  8  transfers the toner image formed on each of the photoconductors  2  onto the sheet P. The fixing device  9  fixes the toner image transferred onto the sheet P thereon. The sheet ejection device  10  ejects the sheet P onto an outside of the image forming apparatus  100 . 
     The transfer device  8  includes an intermediate transfer belt  11 , four primary transfer rollers  12 , and a secondary transfer roller  13 . The intermediate transfer belt  11  is an endless belt serving as an intermediate transferor stretched taut across a plurality of rollers. The four primary transfer rollers  12  serve as primary transferors that transfer yellow, magenta, cyan, and black toner images formed on the photoconductors  2  onto the intermediate transfer belt  11 , respectively, thus forming a full color toner image on the intermediate transfer belt  11 . The secondary transfer roller  13  serves as a secondary transferor that transfers the full color toner image formed on the intermediate transfer belt  11  onto the sheet P. The plurality of primary transfer rollers  12  is pressed against the photoconductors  2 , respectively, via the intermediate transfer belt  11 . Thus, the intermediate transfer belt  11  contacts each of the photoconductors  2 , forming a primary transfer nip therebetween. On the other hand, the secondary transfer roller  13  is pressed against one of the rollers across which the intermediate transfer belt  11  is stretched taut via the intermediate transfer belt  11 . Thus, a secondary transfer nip is formed between the secondary transfer roller  13  and the intermediate transfer belt  11 . 
     The image forming apparatus  100  accommodates a sheet conveyance path  14  through which the sheet P fed from the sheet feeding device  7  is conveyed. A timing roller pair  15  is disposed in the sheet conveyance path  14  at a position between the sheet feeding device  7  and the secondary transfer nip defined by the secondary transfer roller  13 . 
     Referring to  FIG. 1 , a description is provided of printing processes performed by the image forming apparatus  100  having the construction described above. 
     When the image forming apparatus  100  receives an instruction to start printing, a driver drives and rotates the photoconductor  2  clockwise in  FIG. 1  in each of the image forming units  1 Y,  1 M,  1 C, and  1 Bk. The charger  3  charges the surface of the photoconductor  2  uniformly at a high electric potential. Subsequently, the exposure device  6  exposes the surface of each of the photoconductors  2  based on image data created by an original scanner that reads an image on an original or print data instructed by a terminal, thus decreasing the electric potential of an exposed portion on the photoconductor  2  and forming an electrostatic latent image on the photoconductor  2 . The developing device  4  supplies toner to the electrostatic latent image formed on the photoconductor  2 , forming a toner image thereon. 
     When the toner images formed on the photoconductors  2  reach the primary transfer nips defined by the primary transfer rollers  12  in accordance with rotation of the photoconductors  2 , the toner images formed on the photoconductors  2  are transferred onto the intermediate transfer belt  11  driven and rotated counterclockwise in  FIG. 1  successively such that the toner images are superimposed on the intermediate transfer belt  11 , forming a full color toner image thereon. 
     Thereafter, the full color toner image formed on the intermediate transfer belt  11  is conveyed to the secondary transfer nip defined by the secondary transfer roller  13  in accordance with rotation of the intermediate transfer belt  11  and is transferred onto a sheet P conveyed to the secondary transfer nip. The sheet P is supplied from the sheet feeding device  7 . The timing roller pair  15  temporarily halts the sheet P supplied from the sheet feeding device  7 . Thereafter, the timing roller pair  15  conveys the sheet P to the secondary transfer nip at a time when the full color toner image formed on the intermediate transfer belt  11  reaches the secondary transfer nip. Accordingly, the full color toner image is transferred onto and borne on the sheet P. After the toner image is transferred onto the intermediate transfer belt  11 , the cleaner  5  removes residual toner remained on the photoconductor  2  therefrom. 
     The sheet P transferred with the full color toner image is conveyed to the fixing device  9  that fixes the full color toner image on the sheet P. Thereafter, the sheet ejection device  10  ejects the sheet P onto the outside of the image forming apparatus  100 , thus finishing a series of printing processes. 
     A description is provided of a construction of the fixing device  9 . 
     As illustrated in  FIG. 2 , the fixing device  9  according to this embodiment includes a fixing belt  20 , a pressure roller  21 , and a heating device  19 . The fixing belt  20  is an endless belt serving as a fixing rotator or a fixing member. The pressure roller  21  serves as an opposed rotator or an opposed member that contacts an outer circumferential surface of the fixing belt  20  to form a nip, that is, a fixing nip N, between the fixing belt  20  and the pressure roller  21 . The heating device  19  heats the fixing belt  20 . The heating device  19  includes a heater  22 , a heater holder  23 , and a stay  24 . The heater  22  is a laminated heater and serves as a heater or a heating member. The heater holder  23  serves as a holder that holds or supports the heater  22 . The stay  24  serves as a reinforcement that reinforces the heater holder  23  throughout an entire width of the heater holder  23  in a longitudinal direction thereof. Alternatively, the fixing device  9  may be a heating device  99  that includes a driving roller (e.g., the pressure roller  21 ). 
     A detailed description is now given of a construction of the fixing belt  20 . 
     The fixing belt  20  includes a tubular base that is made of polyimide (PI) and has an outer diameter of 25 mm and a thickness in a range of from 40 micrometers to 120 micrometers, for example. The fixing belt  20  further includes a release layer serving as an outermost surface layer. The release layer is made of fluororesin, such as tetrafluoroethylene-perfluoroalkylvinylether copolymer (PFA) and polytetrafluoroethylene (PTFE), and has a thickness in a range of from 5 micrometers to 50 micrometers to enhance durability of the fixing belt  20  and facilitate separation of the sheet P and a foreign substance from the fixing belt  20 . Optionally, an elastic layer that is made of rubber or the like and has a thickness in a range of from 50 micrometers to 500 micrometers may be interposed between the base and the release layer. The base of the fixing belt  20  may be made of heat resistant resin such as polyetheretherketone (PEEK) or metal such as nickel (Ni) and SUS stainless steel, instead of polyimide. An inner circumferential surface of the fixing belt  20  may be coated with polyimide, PTFE, or the like to produce a slide layer. 
     A detailed description is now given of a construction of the pressure roller  21 . 
     The pressure roller  21  has an outer diameter of 25 mm, for example. The pressure roller  21  includes a cored bar  21   a , an elastic layer  21   b , and a release layer  21   c . The cored bar  21   a  is solid and made of metal such as iron. The elastic layer  21   b  is disposed on a surface (e.g., an outer periphery) of the cored bar  21   a . The release layer  21   c  coats an outer surface of the elastic layer  21   b . The elastic layer  21   b  is made of silicone rubber and has a thickness of 3.5 mm, for example. In order to facilitate separation of the sheet P and the foreign substance from the pressure roller  21 , the release layer  21   c  that is made of fluororesin and has a thickness of about 40 micrometers, for example, is preferably disposed on the outer surface of the elastic layer  21   b.    
     A detailed description is now given of a construction of the heater  22 . 
     The heater  22  extends in a longitudinal direction thereof throughout an entire width of the fixing belt  20  in a width direction, that is, an axial direction, of the fixing belt  20 . The heater  22  contacts the inner circumferential surface of the fixing belt  20 . The heater  22  may not contact the fixing belt  20  or may be disposed opposite the fixing belt  20  indirectly via a low friction sheet or the like. However, the heater  22  that contacts the fixing belt  20  directly enhances conduction of heat from the heater  22  to the fixing belt  20 . The heater  22  may contact the outer circumferential surface of the fixing belt  20 . However, if the outer circumferential surface of the fixing belt  20  is brought into contact with the heater  22  and damaged, the fixing belt  20  may degrade quality of fixing the toner image on the sheet P. Hence, the heater  22  contacts the inner circumferential surface of the fixing belt  20  advantageously. 
     The heater  22  includes a base layer  50 , a first insulating layer  51 , a conductor layer  52 , a second insulating layer  53 , and a third insulating layer  54 . The first insulating layer  51 , the conductor layer  52 , and the second insulating layer  53  are layered on the base layer  50  in this order and sandwiched between the base layer  50  and the fixing nip N. The conductor layer  52  includes a heat generator  60 . The third insulating layer  54  is layered on the base layer  50  and is disposed opposite the fixing nip N via the base layer  50 . 
     A detailed description is now given of a construction of the heater holder  23  and the stay  24 . 
     The heater holder  23  and the stay  24  are disposed inside a loop formed by the fixing belt  20 . The stay  24  includes a channel made of metal. Both lateral ends of the stay  24  in a longitudinal direction thereof are supported by side walls (e.g., side plates) of the fixing device  9 , respectively. The stay  24  supports a stay side face of the heater holder  23 , that faces the stay  24  and is opposite a heater side face of the heater holder  23 , that faces the heater  22 . Accordingly, the stay  24  retains the heater  22  and the heater holder  23  to be immune from being bent substantially by pressure from the pressure roller  21 , forming the fixing nip N between the fixing belt  20  and the pressure roller  21 . According to this embodiment, the heater  22  and the pressure roller  21  sandwich the fixing belt  20 . Thus, the heater  22  disposed opposite the inner circumferential surface of the fixing belt  20  serves as a nip former (e.g., a nip forming pad) that forms the fixing nip N between the fixing belt  20  and the pressure roller  21 . Hence, the heater  22  downsizes the fixing device  9  compared to a construction described below with reference to  FIG. 17 , in which the heater  22  is provided separately from a nip forming pad  91 . 
     Since the heater holder  23  is subject to temperature increase by heat from the heater  22 , the heater holder  23  is preferably made of a heat resistant material. For example, if the heater holder  23  is made of heat resistant resin having a decreased thermal conductivity, such as liquid crystal polymer (LCP) and PEEK, the heater holder  23  suppresses conduction of heat thereto from the heater  22 , facilitating heating of the fixing belt  20 . 
     A spring serving as a biasing member causes the fixing belt  20  and the pressure roller  21  to press against each other. Thus, the fixing nip N is formed between the fixing belt  20  and the pressure roller  21 . As a driving force is transmitted to the pressure roller  21  from a driver disposed inside the body  103  of the image forming apparatus  100 , the pressure roller  21  serves as a driving roller that drives and rotates the fixing belt  20 . The fixing belt  20  is driven and rotated by the pressure roller  21  as the pressure roller  21  rotates. While the fixing belt  20  rotates, the fixing belt  20  slides over the heater  22 . In order to facilitate sliding of the fixing belt  20 , a lubricant such as oil and grease may be interposed between the heater  22  and the fixing belt  20 . 
     When printing starts, the driver drives and rotates the pressure roller  21  and the fixing belt  20  starts rotation in accordance with rotation of the pressure roller  21 . Additionally, as power is supplied to the heater  22 , the heater  22  heats the fixing belt  20 . In a state in which the temperature of the fixing belt  20  reaches a predetermined target temperature (e.g., a fixing temperature), as the sheet P bearing the unfixed toner image is conveyed through the fixing nip N formed between the fixing belt  20  and the pressure roller  21  as illustrated in  FIG. 2 , the fixing belt  20  and the pressure roller  21  fix the unfixed toner image on the sheet P under heat and pressure. 
       FIG. 3  is a perspective view of the fixing device  9 .  FIG. 4  is an exploded perspective view of the fixing device  9 . 
     As illustrated in  FIGS. 3 and 4 , the fixing device  9  includes a device frame  40  that includes a first device frame  25  and a second device frame  26 . The first device frame  25  includes a pair of side walls  28  and a front wall  27 . The second device frame  26  includes a rear wall  29 . The side walls  28  are disposed at one lateral end and another lateral end of the fixing belt  20 , respectively, in the width direction of the fixing belt  20 . The side walls  28  support both lateral ends of each of the pressure roller  21  and the heating device  19 , respectively. Each of the side walls  28  includes a plurality of engaging projections  28   a . As the engaging projections  28   a  engage engaging holes  29   a  penetrating through the rear wall  29 , respectively, the first device frame  25  is coupled to the second device frame  26 . 
     Each of the side walls  28  includes an insertion recess  28   b  through which a rotation shaft and the like of the pressure roller  21  are inserted. The insertion recess  28   b  is open at an opening that faces the rear wall  29  and closed at a bottom that is opposite the opening and serves as a contact portion. A bearing  30  that supports the rotation shaft of the pressure roller  21  is disposed at an end of the insertion recess  28   b , that serves as the contact portion. As both lateral ends of the rotation shaft of the pressure roller  21  in an axial direction thereof are attached to the bearings  30 , respectively, the side walls  28  rotatably support the pressure roller  21 . 
     A driving force transmission gear  31  serving as a driving force transmitter is disposed at one lateral end of the rotation shaft of the pressure roller  21  in the axial direction thereof. In a state in which the side walls  28  support the pressure roller  21 , the driving force transmission gear  31  is exposed outside the side wall  28 . Accordingly, when the fixing device  9  is installed in the body  103  of the image forming apparatus  100 , the driving force transmission gear  31  is coupled to a gear disposed inside the body  103  of the image forming apparatus  100  so that the driving force transmission gear  31  transmits the driving force from the driver. Alternatively, a driving force transmitter that transmits the driving force to the pressure roller  21  may be pulleys over which a driving force transmission belt is stretched taut, a coupler, and the like instead of the driving force transmission gear  31 . 
     A pair of supports  32  that supports the fixing belt  20  and the like is disposed at both lateral ends of the heating device  19  in a longitudinal direction thereof, respectively. Each of the supports  32  is a device frame of the heating device  19  and a part of the device frame  40  of the fixing device  9 . The supports  32  support the fixing belt  20  in a state in which the fixing belt  20  is not basically applied with tension in a circumferential direction thereof while the fixing belt  20  does not rotate, that is, by a free belt system. Each of the supports  32  includes guide grooves  32   a . As the guide grooves  32   a  move along edges of the insertion recess  28   b  of the side wall  28 , respectively, the support  32  is attached to the side wall  28 . 
     A pair of springs  33  serving as a pair of biasing members is interposed between each of the supports  32  and the rear wall  29 . As the springs  33  bias the stay  24  and the supports  32  toward the pressure roller  21 , respectively, the fixing belt  20  is pressed against the pressure roller  21  to form the fixing nip N between the fixing belt  20  and the pressure roller  21 . 
     As illustrated in  FIG. 4 , a hole  29   b  is disposed at one lateral end of the rear wall  29  of the second device frame  26  in a longitudinal direction of the second device frame  26 . The hole  29   b  serves as a positioner that positions a body of the fixing device  9  with respect to the body  103  of the image forming apparatus  100 . When the body of the fixing device  9  is installed inside the body  103  of the image forming apparatus  100 , a projection  101  serving as a positioner disposed inside the body  103  of the image forming apparatus  100  is inserted into the hole  29   b  of the fixing device  9 . Accordingly, the projection  101  engages the hole  29   b , positioning the body of the fixing device  9  with respect to the body  103  of the image forming apparatus  100  in a longitudinal direction of the fixing device  9 , that is, the width direction or the axial direction of the fixing belt  20 . Although the hole  29   b  serving as a positioner is disposed at one lateral end of the rear wall  29  in the longitudinal direction of the second device frame  26 , a positioner is not disposed at another lateral end of the rear wall  29 . Thus, the second device frame  26  does not restrict thermal expansion and shrinkage of the body of the fixing device  9  in the longitudinal direction thereof due to temperature change. 
       FIG. 5  is a perspective view of the heating device  19 .  FIG. 6  is an exploded perspective view of the heating device  19 . 
     As illustrated in  FIGS. 5 and 6 , the heater holder  23  includes an accommodating recess  23   a  disposed on a belt side face of the heater holder  23 , that faces the fixing belt  20  and the fixing nip N. The accommodating recess  23   a  is rectangular and accommodates the heater  22 . A connector described below sandwiches the heater  22  and the heater holder  23  in a state in which the accommodating recess  23   a  accommodates the heater  22 , thus holding the heater  22 . 
     Each of the pair of supports  32  includes a belt support  32   b , a belt restrictor  32   c , and a supporting recess  32   d . The belt support  32   b  is C-shaped and inserted into the loop formed by the fixing belt  20 , thus contacting the inner circumferential surface of the fixing belt  20  to support the fixing belt  20 . The belt restrictor  32   c  is a flange that contacts an edge face of the fixing belt  20  to restrict motion (e.g., skew) of the fixing belt  20  in the width direction of the fixing belt  20 . The supporting recess  32   d  is inserted with a lateral end of each of the heater holder  23  and the stay  24  in the longitudinal direction thereof, thus supporting the heater holder  23  and the stay  24 . 
     As illustrated in  FIGS. 5 and 6 , the heater holder  23  includes a positioning recess  23   e , serving as a positioner, disposed at one lateral end of the heater holder  23  in the longitudinal direction thereof. The support  32  includes an engagement  32   e  illustrated in a left part in  FIGS. 5 and 6 . The engagement  32   e  engages the positioning recess  23   e , positioning the heater holder  23  with respect to the support  32  in the longitudinal direction of the heater holder  23 . The support  32  illustrated in a right part in  FIGS. 5 and 6  does not include the engagement  32   e  and therefore the heater holder  23  is not positioned with respect to the support  32  in the longitudinal direction of the heater holder  23 . Thus, the support  32  does not restrict thermal expansion and shrinkage of the heater holder  23  in the longitudinal direction thereof due to temperature change. 
     As illustrated in  FIG. 4 , as the guide grooves  32   a  of the support  32  move along the insertion recess  28   b  of the side wall  28 , the support  32  is attached to the side wall  28  disposed at each lateral end of the device frame  40  in a longitudinal direction thereof. The support  32 , situated at a rear position in  FIG. 4 , of the two supports  32  illustrated in  FIG. 4  positions the heater holder  23  in the longitudinal direction thereof. As the support  32  situated at the rear position in  FIG. 4  is attached to the side wall  28 , the heater holder  23  is positioned with respect to the side wall  28  in the longitudinal direction of the heater holder  23 . Thus, the side wall  28  and the support  32  serve as positioners that position the heater holder  23  with respect to the body of the fixing device  9  in the longitudinal direction of the heater holder  23 . 
     The stay  24  is not positioned with respect to the support  32  in the longitudinal direction of the stay  24 . As illustrated in  FIG. 6 , the stay  24  includes steps  24   a  disposed at both lateral ends of the stay  24  in the longitudinal direction thereof, respectively. The steps  24   a  restrict motion (e.g., dropping) of the stay  24  with respect to the supports  32 , respectively, in the longitudinal direction of the stay  24 . A gap is provided between the step  24   a  and at least one of the supports  32  in the longitudinal direction of the stay  24 . For example, the stay  24  is attached to the supports  32  such that looseness is provided between the stay  24  and each of the supports  32  in the longitudinal direction of the stay  24  so that the supports  32  do not restrict thermal expansion and shrinkage of the stay  24  in the longitudinal direction thereof due to temperature change. That is, the stay  24  is not positioned with respect to one of the supports  32 . 
       FIG. 7  is a plan view of the heater  22 .  FIG. 8  is an exploded perspective view of the heater  22 . 
     Hereinafter, a front side of the heater  22  defines a side that faces the fixing belt  20  and the fixing nip N. A back side of the heater  22  defines a side that faces the heater holder  23 . 
     As illustrated in  FIGS. 7 and 8 , the heater  22  is constructed of a plurality of layers, that is, the base layer  50 , the first insulating layer  51 , the conductor layer  52 , the second insulating layer  53 , and the third insulating layer  54 , which are laminated. The base layer  50  is platy. The first insulating layer  51  is mounted on the front side of the base layer  50 . The conductor layer  52  is mounted on the front side of the first insulating layer  51 . The second insulating layer  53  coats the front side of the conductor layer  52 . The third insulating layer  54  is mounted on the back side of the base layer  50 . The conductor layer  52  includes a pair of heat generators  60 , a pair of electrodes  61 , and a plurality of feeders  62 . Each of the heat generators  60  includes a laminated, resistive heat generator. Each of the electrodes  61  is coupled to one lateral end of each of the heat generators  60  in a longitudinal direction thereof through the feeder  62 . The plurality of feeders  62  includes feeders, each of which couples the electrode  61  to the heat generator  60 , and a feeder that couples the heat generators  60 . As illustrated in  FIG. 7 , at least a part of each of the electrodes  61  is not coated with the second insulating layer  53  and is exposed so that the electrodes  61  are connected to the connector described below. 
     For example, each of the heat generators  60  is produced as below. Silver-palladium (AgPd), glass powder, and the like are mixed into paste. The paste coats the base layer  50  by screen printing or the like. Thereafter, the base layer  50  is subject to firing. Alternatively, the heat generator  60  may be made of a resistive material such as a silver alloy (AgPt) and ruthenium oxide (RuO 2 ). According to this embodiment, the heat generators  60  are parallel to each other and extended in a longitudinal direction of the base layer  50 . One end (e.g., a right end in  FIG. 7 ) of one of the heat generators  60  is electrically connected to one end of another one of the heat generators  60  through the feeder  62 . Another end (e.g., a left end in  FIG. 7 ) of each of the heat generators  60  is electrically connected to the electrode  61  through another feeder  62 . The feeders  62  are made of a conductor having a resistance value smaller than a resistance value of the heat generators  60 . The feeders  62  and the electrodes  61  are made of a material prepared with silver (Ag), silver-palladium (AgPd), or the like by screen printing or the like. 
     The base layer  50  is made of metal such as stainless steel (e.g., SUS stainless steel), iron, and aluminum. Instead of metal, the base layer  50  may be made of ceramic, glass, or the like. If the base layer  50  is made of an insulating material such as ceramic, the first insulating layer  51  sandwiched between the base layer  50  and the conductor layer  52  may be omitted. Since metal has an enhanced durability against rapid heating and is processed readily, metal is preferably used to reduce manufacturing costs. Among metals, aluminum and copper are preferable because aluminum and copper attain an increased thermal conductivity and barely suffer from uneven temperature. Stainless steel is advantageous because stainless steel is manufactured at reduced costs compared to aluminum and copper. 
     Each of the first insulating layer  51 , the second insulating layer  53 , and the third insulating layer  54  is made of heat resistant glass. Alternatively, each of the first insulating layer  51 , the second insulating layer  53 , and the third insulating layer  54  may be made of ceramic, PI, or the like. 
       FIG. 9  is a perspective view of the heater  22  and the heater holder  23 , illustrating a connector  70  attached thereto. The connector  70  serves as a feeding member. 
     As illustrated in  FIG. 9 , the connector  70  includes a housing  71  made of resin and a contact terminal  72  anchored to the housing  71 . The contact terminal  72  is a flat spring. The contact terminal  72  includes a pair of contacts  72   a  that contacts the electrodes  61  of the heater  22 , respectively. The contact terminal  72  of the connector  70  is coupled to a harness  73  that supplies power. 
     As illustrated in  FIG. 9 , the connector  70  is attached to the heater  22  and the heater holder  23  such that the connector  70  sandwiches the heater  22  and the heater holder  23  together at the front side and the back side, respectively. Accordingly, each of the contacts  72   a  of the contact terminal  72  resiliently contacts or presses against the electrode  61  of the heater  22 . Consequently, the heat generators  60  are electrically connected to a power supply disposed in the image forming apparatus  100  through the connector  70 , allowing the power supply to supply power to the heat generators  60 . 
     In order to retain proper conductivity between the contacts  72   a  of the connector  70  and the electrodes  61 , respectively, for an extended period of time, contact pressure with which the connector  70  contacts the electrodes  61  is requested to be retained appropriately. However, the connector  70  may suffer from temperature increase (e.g., overheating) by hot air generated by the heater  22 , heat conducted from the heater  22  through contact portions (e.g., the electrodes  61 ) where the connector  70  contacts the heater  22 , and the like. Accordingly, if the connector  70  does not have a sufficient creep resistance, the connector  70  may suffer from creep deformation as the temperature of the connector  70  increases, thus contacting the electrodes  61  with decreased pressure. Hence, in order to retain conduction between the connector  70  and the electrodes  61  appropriately for an extended period of time, a mechanism to suppress temperature increase of the connector  70  is requested. 
     Although temperature increase of the connector  70  is caused mainly by heat generated by the heater  22 , heat generation of the connector  70  while the connector  70  is energized is also one of causes of temperature increase of the connector  70 . Hence, if heat generation of the connector  70  in accordance with energization of the connector  70  decreases, temperature increase of the connector  70  may be suppressed. 
     To address this circumstance, the connector  70  according to this embodiment is made of a corson copper alloy. The corson copper alloy contains copper (Cu) as a main ingredient and is a copper alloy (e.g., a Cu—Ni—Si alloy) containing at least nickel (Ni) and silicon (Si). Alternatively, in addition to copper, nickel, and silicon, the corson copper alloy may contain at least any one of tin (Su), zinc (Zn), magnesium (Mg), and manganese (Mn). 
     A conductivity of the corson copper alloy is greater than a conductivity of beryllium copper generally used for connectors. That is, a resistance value of the corson copper alloy is smaller than a resistance value of beryllium copper, attaining suppressed heat generation while the connector  70  is energized. Accordingly, the connector  70  made of the corson copper alloy decreases heat generation of the connector  70  while the connector  70  is energized, suppressing temperature increase of the connector  70 . 
     If the contact portions (e.g., the electrodes  61 ) of the heater  22 , that contact the connector  70 , are made of silver or a silver alloy, contact portions (e.g., the contacts  72   a  of the contact terminal  72 ) of the connector  70 , that contact the heater  22 , are preferably coated with silver or the silver alloy. Accordingly, galvanic corrosion caused by contact between different metal materials is suppressed. If the heat generators  60  are produced by printing and firing paste prepared with a silver-palladium alloy, the contact portions of the connector  70  and the heater  22  are made of silver or the silver alloy without gold plating or the like, reducing manufacturing costs. 
       FIG. 10  illustrates comparison in temperature change between a corson copper alloy connector that is equivalent to the connector  70  according to the above-described embodiment and made of the corson copper alloy and a comparative connector according to a comparative example, that is made of beryllium copper. 
     The temperature change in  FIG. 10  illustrates results of a test conducted as below to examine temperature change. Each of the corson copper alloy connector and the comparative connector was placed similarly at a position in proximity to a driving force transmission gear coupled to a pressure roller disposed in fixing devices having an identical construction. 2,500 sheets of A4 size in portrait orientation, that had a ream weight of 90 kg as a weight of 1,000 sheets of paper, such as cards and postcards, were printed at a print speed of 50 sheets per minute (50 ppm) as a single set. When printing was performed for 10 sets, the temperature of each of the corson copper alloy connector and the comparative connector, that is presented by a vertical axis, was measured as time elapsed as presented by a horizontal axis. In  FIG. 10 , a dotted line α indicates temperature change of the comparative connector. A solid line β indicates temperature change of the corson copper alloy connector. 
     As illustrated in  FIG. 10  with the dotted line α, the temperature of the comparative connector increased to 160 degrees Celsius. Conversely, as illustrated with the solid line β, the temperature of the corson copper alloy connector increased to 150 degrees Celsius. It is assumed that the corson copper alloy connector made of the corson copper alloy attained suppressed heat generation while the corson copper alloy connector was energized compared to the comparative connector made of beryllium copper. 
     In addition to the above-described test to examine temperature change of the corson copper alloy connector and the comparative connector, a test to examine contact pressure change of the corson copper alloy connector and the comparative connector was conducted. The contact pressure change was evaluated by measuring a drawing force of the corson copper alloy connector and the comparative connector before temperature increase, that is, before the test started, and after temperature increase, that is, after the test finished. For example, as illustrated in  FIG. 11 , in a state in which the connector  70  sandwiched the heater  22  and the heater holder  23  together, the connector  70  was pulled out. A force gauge measured a maximum static friction force generated as the connector  70  was pulled and started moving. The maximum static friction force was calculated by multiplying contact pressure of the connector  70  by coefficient of friction. Table 1 below illustrates results of the test. 
     
       
         
           
               
               
               
             
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                 Corson copper alloy 
                 Comparative 
               
               
                   
                 connector 
                 connector 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                 Before temperature increase 
                 2.2N 
                 2.3N 
               
               
                 After temperature increase 
                 2.1N 
                 1.8N 
               
               
                   
               
            
           
         
       
     
     As illustrated in Table 1, the maximum static friction force of the corson copper alloy connector before temperature increase was 2.2 N. The maximum static friction force of the corson copper alloy connector after temperature increase was 2.1 N. Thus, the drawing force barely changed before and after temperature increase. Conversely, the maximum static friction force of the comparative connector before temperature increase was 2.3 N. The maximum static friction force of the comparative connector after temperature increase was 1.8 N. Thus, the drawing force decreased by 0.5 N. An identical coefficient of friction was set to the corson copper alloy connector and the comparative connector. Accordingly, a difference in the drawing force indicated a difference in contact pressure with which the corson copper alloy connector and the comparative connector contacted heaters, respectively. The test provided a result that the contact pressure of the corson copper alloy connector decreased less than the contact pressure of the comparative connector. 
     As the results of the tests indicate, the corson copper alloy connector made of the corson copper alloy decreases heat generation while the corson copper alloy connector is energized, compared to the comparative connector made of beryllium copper, thus suppressing temperature increase of the corson copper alloy connector and thereby suppressing decrease in contact pressure of the corson copper alloy connector due to creep deformation. Accordingly, the connector  70  that is equivalent to the corson copper alloy connector and made of the corson copper alloy retains proper contact pressure with which the connector  70  contacts the electrodes  61  for an extended period of time, attaining stable conductivity and enhancing reliability. 
     For example, in a fixing device adapted to high speed printing, a heater is supplied with power of 1,000 W (e.g., at 100 V under 10 A) or more, or power of 1,300 W or more when the heater is supplied with power in a greater amount. Accordingly, a connector generates heat in a substantial amount as the connector is supplied with power. Thus, in the fixing device adapted to high speed printing, temperature increase of the connector is more serious. Hence, the connector  70  according to this embodiment is preferably employed to suppress temperature increase of the connector  70 . 
     In a first configuration as one example, a length K of the heat generator  60  of the heater  22  in the longitudinal direction thereof is greater than a length (e.g., a maximum sheet width Wmax) of a sheet P, serving as a recording medium or a conveyed medium, of a maximum size available in the fixing device  9 , as described below with reference to  FIG. 13 . The length K defines a conveyance span where the sheet P of the maximum size is conveyed. In a second configuration as another example, the heat generator  60  of the heater  22  has a positive temperature coefficient (PTC) property, that is, a positive temperature coefficient of resistance, and an electric current flows through at least a part of the heat generator  60  in the longitudinal direction of the heater  22 . In those configurations also, the connector  70  according to this embodiment is preferably employed. 
     For example, in the first configuration in which the length K of the heat generator  60  is greater than the maximum sheet width Wmax in the longitudinal direction of the heater  22 , the temperature of the heat generator  60  may increase substantially in a non-conveyance span where the sheet P is not conveyed, causing the connector  70  disposed opposite one lateral end of the heater  22  in the longitudinal direction thereof to be subject to temperature increase by heat generated in the non-conveyance span. 
     In the second configuration in which the heat generator  60  has the PTC property and the electric current flows through at least a part of the heat generator  60  in the longitudinal direction of the heater  22 , if the temperature of the heat generator  60  increases in the non-conveyance span, the resistance value of the heat generator  60  increases in the non-conveyance span. Accordingly, temperature increase of the heat generator  60  in the non-conveyance span accelerates, causing the connector  70  to be subject to temperature increase. 
     Temperature increase resulting from the PTC property is not limited to a pattern in which the two heat generators  60  are connected in series as illustrated in  FIG. 7 .  FIG. 12  illustrates a heater  22 P incorporating the heat generators  60  connected in parallel. For example, temperature increase resulting from the PTC property may occur similarly also in a pattern in which the heat generators  60  are connected in parallel as illustrated in  FIG. 12 , at least if the heat generators  60  have a component Ix that flows an electric current in the longitudinal direction of the heat generators  60 .  FIG. 12  also illustrates a component Iy that flows the electric current in a direction perpendicular to a longitudinal direction of the heater  22 P. 
     For example, as illustrated in an enlarged view enclosed by an alternate long and short dash line in  FIG. 12 , when a sheet P is conveyed over the fixing belt  20  such that an edge h of the sheet P in the width direction thereof passes from one end of the single heat generator  60  to another end of the single heat generator  60 , the electric current flows from a non-conveyance region  60   a  of the heat generator  60  where the sheet P is not conveyed and therefore the temperature is high to a conveyance region  60   b  where the sheet P is conveyed and therefore the temperature is low, similarly to the pattern in which the heat generators  60  are connected in series. Accordingly, a heat generation amount of the non-conveyance region  60   a  is greater than a heat generation amount of the conveyance region  60   b , accelerating temperature increase of the connector  70 . Hence, in the configurations described above in which temperature increase of the heat generators  60  are substantial or accelerated in the non-conveyance region  60   a , the connector  70  according to this embodiment is employed to achieve substantial advantages. 
     The connector  70  decreases heat generation thereof while the connector  70  is supplied with power, allowing employment of various layouts described below advantageously. 
     As illustrated in  FIG. 13  as one example, the driving force transmission gear  31  is disposed at one lateral end of the pressure roller  21  in the axial direction thereof. The driving force transmission gear  31  and the connector  70  are disposed in an identical side (e.g., a right side in  FIG. 13 ), that is, a feeding side FS, defined by a center M of the heat generators  60  in the longitudinal direction of the heater  22 . 
     In the feeding side FS, the driving force transmission gear  31  meshes with the gear disposed inside the body  103  of the image forming apparatus  100 , generating heat. Accordingly, an ambient temperature in the feeding side FS is subject to a temperature higher than an ambient temperature of a non-feeding side NS opposite the feeding side FS in the longitudinal direction of the heater  22 . Additionally, in a model of the fixing device  9 , that is adapted to high speed printing, in order to increase a length of the fixing nip N in a sheet conveyance direction, the elastic layer  21   b , serving as a viscoelastic layer, of the pressure roller  21  is requested to be compressed substantially at the fixing nip N. As the elastic layer  21   b  is compressed, the elastic layer  21   b  is deformed viscoelastically, increasing torque that increases an amount of heat generated at the driving force transmission gear  31 . 
     Additionally, while the fixing belt  20  slides over the heater  22 , a frictional resistance generates, increasing torque that increases the amount of heat generated at the driving force transmission gear  31 . Hence, if the connector  70  generates an increased amount of heat as the connector  70  is supplied with power, the connector  70  is not preferably disposed in proximity to the driving force transmission gear  31  that generates heat. To address this circumstance, the connector  70  according to this embodiment is made of the corson copper alloy to decrease heat generation of the connector  70  while the connector  70  is energized. Hence, the connector  70  is disposed in the feeding side FS where the driving force transmission gear  31  that generates heat is disposed. 
     As illustrated in  FIG. 13 , the connector  70  made of the corson copper alloy allows the stay  24  to extend in the longitudinal direction thereof such that one lateral end (e.g., a right end in  FIG. 13 ) of the stay  24  in the longitudinal direction thereof is disposed opposite the connector  70  or extended outboard beyond the connector  70  in the longitudinal direction of the heater  22 . 
     Heat is conducted from the heater  22  to the connector  70  directly through a path indicated with an arrow A in  FIG. 13 . Additionally, heat is conducted from the heater  22  to the stay  24  through the heater holder  23 , increasing an ambient temperature of a periphery of the stay  24 . Heat is conducted from the periphery of the stay  24  to the connector  70  through a path indicated with an arrow B in  FIG. 13 . Accordingly, if the stay  24  extends to a position where the stay  24  is disposed opposite the connector  70  or a position where the stay  24  is in proximity to the connector  70 , the connector  70  is susceptible to heat conducted through the stay  24 . For example, if the stay  24  is made of a material having a thermal conductivity greater than a thermal conductivity of the heater holder  23 , the connector  70  is more susceptible to heat conducted through the stay  24 . Hence, if the connector  70  generates an increased amount of heat as the connector  70  is supplied with power, the stay  24  is not preferably disposed in proximity to the connector  70 . 
     To address this circumstance, the connector  70  according to this embodiment is made of the corson copper alloy to decrease heat generation of the connector  70  while the connector  70  is energized, allowing the stay  24  to be disposed opposite the connector  70  or extended outboard beyond the connector  70  in the longitudinal direction of the heater  22 . 
     Since the stay  24  extends to the position where the stay  24  is disposed opposite the connector  70  or extends outboard beyond the connector  70  in the longitudinal direction of the heater  22 , the support  32  that supports the stay  24  has an increased width in the longitudinal direction of the stay  24 . Accordingly, the spring  33  that biases the stay  24  via the support  32  has an increased diameter. Consequently, the fixing device  9  employs the spring  33  that presses against the support  32  with increased pressure, increasing the length of the fixing nip N in the sheet conveyance direction and thereby attaining high speed printing. 
       FIG. 14  is a plan view of the image forming apparatus  100 , illustrating one example of a layout inside the body  103  of the image forming apparatus  100 . 
     According to the example of the image forming apparatus  100  illustrated in  FIG. 14 , a high voltage board  41  that supplies power to the chargers  3  and the like of the image forming units  1 Y,  1 M,  1 C, and  1 Bk, respectively, is disposed on the left of the image forming units  1 Y,  1 M,  1 C, and  1 Bk in  FIG. 14 . Conversely, a fixing motor  42 , an image forming motor  43 , and a power supply  44  are disposed on the right of the image forming units  1 Y,  1 M,  1 C, and  1 Bk in  FIG. 14 . The fixing motor  42  serves as a fixing driver that drives the elements of the fixing device  9  such as the pressure roller  21 . The image forming motor  43  serves as an image forming driver that drives the photoconductor  2 , the developing device  4 , and the like of each of the image forming units  1 Y,  1 M,  1 C, and  1 Bk. The power supply  44  is a power supply unit (PSU) that supplies power to the fixing motor  42 , the image forming motor  43 , the heater  22  of the fixing device  9 , and the like. 
     The fixing motor  42 , the image forming motor  43 , and the power supply  44  that are disposed on the right of the image forming units  1 Y,  1 M,  1 C, and  1 Bk generate heat as the fixing motor  42 , the image forming motor  43 , and the power supply  44  are driven or supplied with power. To address this circumstance, the connector  70  according to this embodiment is made of the corson copper alloy to decrease heat generation of the connector  70  while the connector  70  is energized. Accordingly, the connector  70 , together with the fixing motor  42 , the image forming motor  43 , and the power supply  44  that generate heat, is disposed in an identical side, that is, the feeding side FS, defined by the center M of the heat generators  60  in the longitudinal direction thereof. 
     Thus, the connector  70 , the fixing motor  42 , the image forming motor  43 , and the power supply  44  are disposed in the identical side, shortening a harness and the like that electrically connect the connector  70 , the fixing motor  42 , the image forming motor  43 , and the power supply  44 . Accordingly, the image forming apparatus  100  is manufactured at reduced costs and assembled readily. Alternatively, the power supply  44  may be orientated such that a longitudinal direction of the power supply  44  is parallel to the longitudinal direction of the heater  22 . In this case, the power supply  44  may be disposed in proximity to the connector  70  such that a center of the power supply  44  in the longitudinal direction thereof is situated closer to the connector  70  than the center M of the heat generators  60  in the longitudinal direction thereof is. 
     According to the example of the image forming apparatus  100  illustrated in  FIG. 14 , a fan  46  serving as an exhaust fan is disposed inside the body  103  of the image forming apparatus  100 . An inlet  110  is disposed in a front cover (e.g., an upper cover in  FIG. 14 ) of the body  103  of the image forming apparatus  100 . An inlet  111  is disposed in one of both side covers (e.g., a left side cover in  FIG. 14 ) of the body  103  of the image forming apparatus  100 . An outlet  112  is disposed in another one of both side covers (e.g., a right side cover in  FIG. 14 ) of the body  103  of the image forming apparatus  100 . As the fan  46  is driven by power supplied from the power supply  44 , air flow indicated with arrows in  FIG. 14  generates inside the body  103  of the image forming apparatus  100 . Air enters from the outside of the image forming apparatus  100  into the body  103  of the image forming apparatus  100  through each of the inlets  110  and  111 . Air is exhausted from the body  103  of the image forming apparatus  100  through the outlet  112 . While air passes inside the body  103  of the image forming apparatus  100 , air draws heat from the fixing device  9 , the fixing motor  42 , the image forming motor  43 , the power supply  44 , and the like and is exhausted. Thus, air cools the fixing device  9 , the fixing motor  42 , the image forming motor  43 , the power supply  44 , and the like, suppressing temperature increase thereof. 
     Since air passing inside the body  103  of the image forming apparatus  100  absorbs heat inside the body  103 , a temperature at a position in proximity to the outlet  112  is higher than temperatures at positions in proximity to the inlets  110  and  111 , respectively. Hence, if the connector  70  is situated at the position in proximity to the outlet  112 , air heated to a high temperature heats the connector  70 . For example, if the image forming apparatus  100  is a model adapted to high speed printing, the image forming apparatus  100  generates an increased amount of heat inside the body  103  thereof, causing serious temperature increase in a periphery of the connector  70 . A cover of the fixing device  9  has a gear slot disposed opposite the driving force transmission gear  31  mounted on the pressure roller  21 . The driving force transmission gear  31  is coupled to the gear disposed inside the body  103  of the image forming apparatus  100  through the gear slot. The fixing device  9  also has a sheet slot through which a sheet P is conveyed into the fixing device  9 . As hot air moves from the sheet slot to the gear slot, the temperature inside the fixing device  9  increases. To address this circumstance, the fan  46  may increase air flow, for example, to decrease the temperature inside the fixing device  9 . However, noise and the size of the image forming apparatus  100  may increase disadvantageously. 
     In view of those circumstances and temperature increase of the connector  70 , the connector  70  is not preferably disposed in proximity to the outlet  112 . To address this circumstance, the connector  70  according to this embodiment is made of the corson copper alloy to decrease heat generation of the connector  70  while the connector  70  is energized. Hence, the connector  70  is disposed in proximity to the outlet  112  that might be subject to hot air.  FIG. 14  illustrates an example of the image forming apparatus  100  in which the connector  70  and the outlet  112  are disposed in an identical side, that is, the feeding side FS, defined by the center M of the heat generators  60  in the longitudinal direction thereof. Accordingly, the fan  46  disposed in proximity to the outlet  112  is also disposed in the identical side, that is, the feeding side FS, defined by the center M of the heat generators  60  in the longitudinal direction thereof, where the connector  70  is disposed. Consequently, according to the example of the image forming apparatus  100  illustrated in  FIG. 14 , the fan  46  and the power supply  44  are disposed in the identical side, that is, the feeding side FS, shortening the harness and the like that electrically connect the power supply  44  to the fan  46  and thereby facilitating assembly at reduced manufacturing costs. 
     Additionally, according to the example of the image forming apparatus  100  illustrated in  FIG. 14 , the outlet  112  is disposed in the right side cover in  FIG. 14  of the body  103  of the image forming apparatus  100 . Accordingly, hot air exhausted from the outlet  112  does not blow against a user of the image forming apparatus  100 , who stands in front of the front cover of the body  103 , thus enhancing comfort. For example, the outlet  112  is preferably disposed in a face other than a face that is faced by the user who operates the image forming apparatus  100  and is mounted with a controller such as a control panel. 
       FIG. 15  is a plan view of an image forming apparatus  100 S, illustrating another example of the layout inside the body  103 . 
     According to the example of the image forming apparatus  100 S illustrated in  FIG. 15 , air flow is directed in a leftward direction opposite a rightward direction in which air flow is directed in the image forming apparatus  100  as described above with reference to  FIG. 14 . For example, according to the example of the image forming apparatus  100 S illustrated in  FIG. 15 , a fan  47  serving as an intake fan intakes air from an outside of the image forming apparatus  100 S through the inlet  111  disposed in the right side cover in  FIG. 15 . Air is exhausted from the body  103  of the image forming apparatus  100 S through the outlet  112  disposed in the left side cover in  FIG. 15 . The temperature of air passing inside the body  103  of the image forming apparatus  100 S is higher in the feeding side FS, that is, a left side in  FIG. 15  than in the non-feeding side NS, that is, a right side in  FIG. 15 . 
     However, since the connector  70  is made of the corson copper alloy, the connector  70  is disposed in the left side in  FIG. 15 , that is, an identical side where the outlet  112  is disposed. The left side in  FIG. 15  is the feeding side FS defined by the center M of the heat generators  60  in the longitudinal direction thereof. In view of a positional relation of the connector  70  with respect to the inlet  111  disposed on the right of the connector  70  in  FIG. 15  and the fan  47  disposed in proximity to the inlet  111 , the connector  70  is disposed in the feeding side FS defined by the center M of the heat generators  60  in the longitudinal direction thereof, that is opposite the non-feeding side NS where the inlet  111  and the fan  47  are disposed. 
     According to the example of the image forming apparatus  100 S illustrated in  FIG. 15 , a fan  48  is disposed in proximity to the inlet  110  disposed in the front cover, that is, an upper cover in  FIG. 15 , of the body  103  of the image forming apparatus  100 S, separately from the fan  47 . The fan  48  blows air against a sheet guide  57  illustrated in  FIG. 16  disposed above the fixing device  9 , the sheet ejection device  10  disposed in a periphery of the sheet guide  57 , and the like, thus cooling the sheet guide  57  and the sheet ejection device  10 . Additionally, the fan  48  ventilates the sheet guide  57  and the periphery thereof, suppressing condensation. A part of air intaken through the inlet  110  disposed in the front cover is heated while passing through the fixing device  9  and is moved to the connector  70 . However, since the connector  70  is made of the corson copper alloy that suppresses temperature increase of the connector  70 , the connector  70  is used without faults. 
       FIG. 16  is a plan view of an image forming apparatus  100 T, illustrating yet another example of the layout inside the body  103 . 
     As the power supply  44  disposed inside the body  103  of the image forming apparatus  100  generates heat, an ambience around the power supply  44 , that is heated by the power supply  44 , usually moves upward in a direction indicated with an arrow C in  FIG. 16 . Hence, if the power supply  44  is situated below the fixing device  9 , the connector  70  disposed inside the fixing device  9  is susceptible to heat from the power supply  44 . To address this circumstance, the connector  70  according to this embodiment is made of the corson copper alloy to decrease heat generation of the connector  70  while the connector  70  is energized. Hence, the power supply  44  is disposed below the fixing device  9  safely at a position where the power supply  44  overlaps the fixing device  9  in a gravity direction. 
     As described above, the connector  70  made of the corson copper alloy allows employment of various layouts of the image forming apparatuses  100 ,  100 S, and  100 T. For example, since the connector  70  decreases heat generation thereof as the connector  70  is supplied with power, the connector  70  is disposed in proximity to the driving force transmission gear  31 , various motors (e.g., the fixing motor  42  and the image forming motor  43 ), the power supply  44 , and the like that generate heat, thus improving flexibility in layout. Additionally, the connector  70  is disposed in proximity to a heat generating source such as the driving force transmission gear  31 , downsizing the fixing device  9 . Downsizing of the fixing device  9  is preferable and advantageous if the fixing device  9  is adapted to low speed printing and therefore requested to be downsized. 
     The embodiments of the present disclosure are applicable to fixing devices  9 S,  9 T, and  9 U illustrated in  FIGS. 17 to 19 , respectively, other than the fixing device  9  described above. The following briefly describes a construction of each of the fixing devices  9 S,  9 T, and  9 U depicted in  FIGS. 17 to 19 , respectively. 
     A description is provided of a construction of the fixing device  9 S depicted in  FIG. 17 . 
     As illustrated in  FIG. 17 , the fixing device  9 S includes a pressing roller  90  disposed opposite the pressure roller  21  via the fixing belt  20 . The pressing roller  90  and the heater  22  sandwich the fixing belt  20  so that the heater  22  heats the fixing belt  20 . On the other hand, the nip forming pad  91  is disposed inside the loop formed by the fixing belt  20  and disposed opposite the pressure roller  21 . The stay  24  supports the nip forming pad  91 . The nip forming pad  91  and the pressure roller  21  sandwich the fixing belt  20  and define the fixing nip N. 
     A description is provided of a construction of the fixing device  9 T depicted in  FIG. 18 . 
     As illustrated in  FIG. 18 , the fixing device  9 T does not include the pressing roller  90  described above with reference to  FIG. 17 . In order to attain a contact length for which the heater  22  contacts the fixing belt  20  in the circumferential direction thereof, the heater  22  is curved into an arc in cross section that corresponds to a curvature of the fixing belt  20 . Other construction of the fixing device  9 T is equivalent to that of the fixing device  9 S depicted in  FIG. 17 . 
     A description is provided of a construction of the fixing device  9 U depicted in  FIG. 19 . 
     As illustrated in  FIG. 19 , the fixing device  9 U includes a pressure belt  92  in addition to the fixing belt  20 . The pressure belt  92  and the pressure roller  21  form a fixing nip N 2  serving as a secondary nip separately from a heating nip N 1  serving as a primary nip formed between the fixing belt  20  and the pressure roller  21 . For example, the nip forming pad  91  and a stay  93  are disposed opposite the fixing belt  20  via the pressure roller  21 . The pressure belt  92  that is rotatable accommodates the nip forming pad  91  and the stay  93 . As a sheet P bearing a toner image is conveyed through the fixing nip N 2  formed between the pressure belt  92  and the pressure roller  21 , the pressure belt  92  and the pressure roller  21  fix the toner image on the sheet P under heat and pressure. Other construction of the fixing device  9 U is equivalent to that of the fixing device  9  depicted in  FIG. 2 . 
     The heaters  22  and  22 P according to the embodiments of the present disclosure are also applicable to devices other than the fixing devices  9 ,  9 S,  9 T, and  9 U. For example, the heaters  22  and  22 P according to the embodiments of the present disclosure are also applicable to a dryer installed in an image forming apparatus employing an inkjet method. The dryer dries ink applied onto a sheet. Alternatively, the heaters  22  and  22 P according to the embodiments of the present disclosure may be applied to a coater (e.g., a laminator) that thermally presses film serving as a coating member onto a surface of a sheet (e.g., paper) serving as a conveyed medium while a belt conveys the sheet. The heating device  99  according to the embodiments of the present disclosure is not limited to a belt heating device that heats a belt and may be a heating device that does not incorporate the belt. 
     A description is provided of advantages of a heating device (e.g., the heating device  99 ). 
     As illustrated in  FIGS. 2, 9, and 12 , the heating device includes a heater (e.g., the heaters  22  and  22 P) and a feeding member (e.g., the connector  70 ). As illustrated in  FIGS. 7 and 12 , the heater is a laminated heater, for example. The heater includes a heat generator (e.g., the heat generator  60 ) that generates heat as the heat generator is supplied with power. The feeding member contacts the heater and feeds power to the heat generator. The feeding member is made of a corson copper alloy. 
     Since the feeding member is made of the corson copper alloy, the feeding member decreases heat generation thereof while the feeding member is energized, suppressing temperature increase of the feeding member. 
     According to the embodiments described above, the fixing belt  20  serves as an endless belt. Alternatively, a fixing film, a fixing sleeve, or the like may be used as an endless belt. Further, the pressure roller  21  serves as an opposed rotator. Alternatively, a pressure belt or the like may be used as an opposed rotator. 
     The above-described embodiments are illustrative and do not limit the present disclosure. Thus, numerous additional modifications and variations are possible in light of the above teachings. For example, elements and features of different illustrative embodiments may be combined with each other and substituted for each other within the scope of the present disclosure. 
     Any one of the above-described operations may be performed in various other ways, for example, in an order different from the one described above.