Patent Publication Number: US-2023161283-A1

Title: Fixing device and image forming apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 2021-191420 filed Nov. 25, 2021. 
     BACKGROUND 
     (i) Technical Field 
     The present disclosure relates to a fixing device and an image forming apparatus. 
     (ii) Related Art 
     Japanese Unexamined Patent Application Publication No. 2002-148973 discloses an image forming apparatus in which the distance between a transport member, which is made of endless wires, and a transport auxiliary member is smaller at an outlet of a transfer material than at an inlet of the transfer material. By rotating transport pulleys with a rotational driving source, the transport member and the transport auxiliary member are driven to transport the transfer material, an unfixed toner image is heat-fused by radiant heat, and the transfer material is transported to a guide member at the inlet of a calender roller. 
     A known image forming apparatus includes: a pair of endless circulating parts disposed on both sides of a recording medium being transported, in the width direction of the recording medium; and holding parts extending in the width direction of the recording medium, attached to the pair of circulating parts at both ends thereof, and configured to hold the leading end of a recording medium. The pair of circulating parts transport the recording medium. Furthermore, to heat, in a non-contact manner, the recording medium being transported, a heating part, such as a heater, is disposed so as to oppose the recording medium being transported. 
     With this configuration, because the heating part and the circulating parts overlap each other in the width direction of the recording medium, the circulating parts are heated by the heating part, and the temperature of the circulating parts increase. 
     SUMMARY 
     Aspects of non-limiting embodiments of the present disclosure relate to preventing the circulating parts from being heated by the heating part, compared with a configuration in which the heating part and the circulating parts overlap each other in the width direction of the recording medium. 
     Aspects of certain non-limiting embodiments of the present disclosure overcome the above disadvantages and/or other disadvantages not described above. However, aspects of the non-limiting embodiments are not required to overcome the disadvantages described above, and aspects of the non-limiting embodiments of the present disclosure may not overcome any of the disadvantages described above. 
     According to an aspect of the present disclosure, there is provided a fixing device including: a holding part that extends in a width direction of a recording medium being transported and that holds the recording medium; a pair of circulating parts that are attached to both ends of the holding part and that circulate to transport the recording medium; and a heating member that heats the recording medium in a non-contact manner and that is located in a space between the pair of circulating parts in the width direction. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Exemplary embodiments of the present disclosure will be described in detail based on the following figures, wherein: 
         FIG.  1    is a front view of a fixing device according to a first exemplary embodiment of the present disclosure; 
         FIG.  2    is a side view of the fixing device according to the first exemplary embodiment of the present disclosure; 
         FIG.  3    is a perspective view showing chains, a holding part, and the like provided on the fixing device according to the first exemplary embodiment of the present disclosure; 
         FIG.  4    is a plan view showing the chains, the holding part, and the like provided on the fixing device according to the first exemplary embodiment of the present disclosure; 
         FIG.  5    is a perspective view showing a heating part, and the like provided on the fixing device according to the first exemplary embodiment of the present disclosure; 
         FIG.  6    is a sectional view showing the heating part, and the like provided on the fixing device according to the first exemplary embodiment of the present disclosure; 
         FIG.  7    is a sectional view showing a cooling unit provided on an image forming apparatus according to the first exemplary embodiment of the present disclosure; 
         FIG.  8    shows a configuration of a toner image forming unit provided on the image forming apparatus according to the first exemplary embodiment of the present disclosure; 
         FIG.  9    shows a configuration of the image forming apparatus according to the first exemplary embodiment of the present disclosure; 
         FIG.  10    is a front view of a fixing device according to a comparative example of the present disclosure; 
         FIG.  11    is a front view of a fixing device according to a second exemplary embodiment of the present disclosure; and 
         FIG.  12    is a side view of the fixing device according to the second exemplary embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     First Exemplary Embodiment 
     An example of a fixing device and an example of an image forming apparatus according to a first exemplary embodiment of the present disclosure will be described below with reference to  FIGS.  1  to  10   . Note that, in the figures, arrow H represents the top-bottom direction of the apparatus (vertical direction), arrow W represents the width direction of the apparatus (horizontal direction), and arrow D represents the depth direction of the apparatus (horizontal direction). 
     Image Forming Apparatus 
     An image forming apparatus  10  according to the first exemplary embodiment is an electrophotographic image forming apparatus that forms a toner image on a sheet member P, serving as a recording medium. As shown in  FIG.  9   , the image forming apparatus  10  includes storage parts  50 , an output part  52 , an image forming unit  12 , a transport mechanism  60 , a reversing mechanism  80 , a fixing device  100 , and a cooling unit  90 . 
     Storage Part 
     The storage parts  50  accommodate sheet members P. The image forming apparatus  10  includes multiple (for example, two) storage parts  50 . The sheet members P are selectively sent out from the storage parts  50 . 
     Output Part 
     The output part  52  is a portion on which a sheet member P is discharged after an image has been formed thereon. More specifically, after an image is fixed to a sheet member P in the fixing device  100 , the sheet member P is cooled in the cooling unit  90  and is discharged on the output part  52 . 
     Image Forming Unit 
     The image forming unit  12  electrophotographically forms an image on a sheet member P. More specifically, the image forming unit  12  includes toner image forming units  20  that form toner images, and a transfer device  30  that transfers the toner images formed on the toner image forming units  20  to a sheet member P. The image forming unit  12  is an example of a forming unit. 
     There are multiple toner image forming units  20 , so that toner images of different colors are formed. The image forming apparatus  10  includes four toner image forming units  20 , which correspond to yellow (Y), magenta (M), cyan (C), and black (K). The letters (Y), (M), (C), and (K) in  FIG.  9    represent the components corresponding to these colors. 
     Toner Image Forming Unit 
     The toner image forming units  20  corresponding to the respective colors have basically the same configuration, except for the toners. More specifically, as shown in  FIG.  8   , each toner image forming unit  20  includes a photoconductor drum  21  (photoconductor) that rotates in the direction of arrow A, and a charger  22  that charges the photoconductor drum  21 . The toner image forming unit  20  also includes an exposure device  23  that exposes the photoconductor drum  21  charged by the charger  22  to form an electrostatic latent image on the photoconductor drum  21 , and a developing device  24  that develops, with toner, the electrostatic latent image formed on the photoconductor drum  21  by the exposure device  23  to form a toner image. 
     Transfer Device 
     The transfer device  30  first-transfers toner images on the photoconductor drums  21  corresponding to the respective colors to an intermediate transfer body in a superposed manner, and second-transfers the superposed toner image to a sheet member P. More specifically, as shown in  FIG.  9   , the transfer device  30  includes a transfer belt  31 , serving as an intermediate transfer body, first transfer rollers  33 , and a transfer part  35 . 
     The first transfer rollers  33  transfer the toner images formed on the photoconductor drums  21  to the transfer belt  31  at first transfer positions T (see  FIG.  8   ) between the photoconductor drums  21  and the first transfer rollers  33 . 
     The transfer belt  31  is an endless belt stretched over multiple rollers  32  in a certain orientation. The transfer belt  31  rotates in the direction of arrow B when at least one of the rollers  32  is rotationally driven, and transports the first-transferred image to a second transfer position NT. 
     The transfer part  35  transfers the toner image, which has been transferred to the transfer belt  31 , to a sheet member P. More specifically, the transfer part  35  includes a second transfer part  34  and an opposing roller  36 . 
     The opposing roller  36  is disposed below the transfer belt  31  so as to oppose the transfer belt  31 . The second transfer part  34  is disposed inside the transfer belt  31  such that the transfer belt  31  is located between the second transfer part  34  and the opposing roller  36 . The second transfer part  34  is a corotron. At the transfer part  35 , the toner image that has been transferred to the transfer belt  31  is transferred to a sheet member P passing through the second transfer position NT by an electrostatic force produced by discharging of the second transfer part  34 . 
     Transport Mechanism 
     The transport mechanism  60  transports a sheet member P stored in a storage part  50  to the second transfer position NT and then to a heating part  120  (described below). 
     More specifically, the transport mechanism  60  includes feed-out rollers  62 , multiple transport rollers  64 , and a chain gripper  66 . 
     The feed-out rollers  62  feed out sheet members P stored in the storage parts  50 . The transport rollers  64  transport a sheet member P fed out by a feed-out roller  62  to the chain gripper  66  or transport a sheet member P transported by the chain gripper  66  to the cooling unit  90 . 
     The chain gripper  66  transports a sheet member P by holding the leading end of the sheet member P. More specifically, as shown in  FIG.  3   , the chain gripper  66  includes a pair of chains  72  and holding parts  68  that hold the leading ends of sheet members P. A one-dot chain line indicates a portion of the transport path along which a sheet member P is transported in the transport mechanism  60 . 
     In this exemplary embodiment, the chains  72  and the holding parts  68 , which constitute the chain gripper  66 , also constitute the fixing device  100 . Details of the chains  72  and the holding parts  68  will be described below. 
     Reversing Mechanism 
     The reversing mechanism  80  reverses a sheet member P. More specifically, as shown in  FIG.  9   , the reversing mechanism  80  includes multiple transport rollers  82 , a reversing device  84 , and multiple transport rollers  86 . 
     The transport rollers  82  transport a sheet member P delivered from the fixing device  100  to the reversing device  84 . The reversing device  84  reverses the sheet member P by, for example, transporting the sheet member P while turning back several times such that the sheet transport direction changes by, for example, 90 degrees each time to twist the sheet member P in the form of a Mobius strip. 
     The transport rollers  86  transport the sheet member P reversed in the reversing device  84  to the chain gripper  66 . 
     Fixing Device 
     The fixing device  100  fixes a toner image transferred to a sheet member P by the transfer device  30  to the sheet member P. Details of the fixing device  100  will be described below. 
     Cooling Unit 
     The cooling unit  90  cools a sheet member P heated in the fixing device  100 . As shown in  FIG.  9   , the cooling unit  90  is located downstream of the fixing device  100  in the sheet transport direction. The cooling unit  90  includes two cooling rollers  92  arranged side-by-side in the width direction of the apparatus. Because the two cooling rollers  92  have the same configuration, one of the cooling rollers  92  will be described. 
     As shown in  FIG.  7   , the cooling rollers  92  include a roller  92   a  disposed above the sheet transport path and a roller  92   b  disposed below the sheet transport path. 
     The rollers  92   a  and  92   b  are cylindrical and extend in the depth direction of the apparatus. The rollers  92   a  and  92   b  have cylindrical base members  94   a  and  94   b . The base members  94   a  and  94   b  are aluminum pipes, and flows of air generated by an air-sending mechanism (not shown) pass through the base members  94   a  and  94   b . The flows of air reduce the surface temperatures of the rollers  92   a  and  92   b , compared with a configuration in which the flows of air are not generated. 
     In this configuration, the roller  92   b  receives a rotational force from a driving member (not shown) and rotates. Furthermore, the roller  92   a  is driven by the roller  92   b  and rotates. The rollers  92   a  and  92   b  transport the sheet member P nipped therebetween to cool the sheet member P. 
     Effect of Image Forming Apparatus 
     The image forming apparatus  10  shown in  FIG.  9    forms an image as follows. 
     First, the energized chargers  22  corresponding to the respective colors (see  FIG.  8   ) uniformly charge the surfaces of the corresponding photoconductor drums  21  to a predetermined negative electric potential. Then, based on the image data input from the outside, the exposure devices  23  radiate exposure light onto the surfaces of the charged photoconductor drums  21  to form electrostatic latent images. 
     As a result, electrostatic latent images corresponding to the image data are formed on the surfaces of the photoconductor drums  21 . The developing devices  24  develop the electrostatic latent images into visible toner images. The transfer device  30  transfers the toner images formed on the surfaces of the photoconductor drums  21  to the transfer belt  31 . 
     A sheet member P fed out from a storage part  50  shown in  FIG.  9    to the sheet transport path by a feed-out roller  62  and transported by the chain gripper  66  is sent to a second transfer position NT, where the transfer belt  31  and the opposing roller  36  are in contact with each other. At the second transfer position NT, the sheet member P is transported between the transfer belt  31  and the opposing roller  36 , whereby the toner image on the surface of the transfer belt  31  is transferred to the surface of the sheet member P. 
     Furthermore, the fixing device  100  fixes, to the sheet member P, the toner image transferred to the surface of the sheet member P, and the sheet member P is transported to the cooling unit  90 . The cooling unit  90  cools the sheet member P to which the toner image has been fixed, and discharges the sheet member P to the output part  52 . 
     When a toner image is to be formed on the back surface of a sheet member P, the sheet member P that has been transported by the chain gripper  66  and has passed through the fixing device  100  is transported to the transport rollers  82  of the reversing mechanism  80 . The sheet member P transported by the transport rollers  82  is reversed by the reversing device  84 . Furthermore, the transport rollers  86  transport the reversed sheet member P to the chain gripper  66 . The chain gripper  66  transports the sheet member P. Then, the above-described process is performed again to form a toner image on the back surface of the sheet member P. 
     Configuration of Relevant Part 
     Next, the fixing device  100  will be described. 
     As shown in  FIG.  2   , the fixing device  100  includes the chain gripper  66  and a preheating part  102  that is located downstream of the transfer device  30  (see  FIG.  9   ) in the sheet transport direction and that heats the sheet member P in a non-contact manner. 
     The fixing device  100  also includes the heating part  120  that comes into contact with the sheet member P to apply heat and pressure, a blowing unit  170 , and heat shielding members  108  (see  FIG.  1   ) that block the heat radiated from the preheating part  102  and transferred to the chains  72  of the chain gripper  66 . 
     Chain Gripper 
     The chain gripper  66  includes a pair of chains  72  and the holding parts  68  for holding sheet members P. The chains  72  are an example of circulating parts. 
     Chains 
     As shown in  FIG.  3   , the pair of chains  72  are disposed at a distant from each other in the depth direction of the apparatus. The chains  72  are endless chains and include multiple metal outer plates  72   a , multiple metal inner plates  72   b , and pins  72   c  connecting the outer plates  72   a  and the inner plates  72   b . In this exemplary embodiment, the depth direction of the apparatus is equal to the width direction of the sheet member P to be transported. 
     The chains  72  are disposed at one end and the other end of the opposing roller  36  (see  FIG.  9   ) in the axial direction and are stretched over a pair of sprockets (not shown) having axes extending in the depth direction of the apparatus, a pair of sprockets  71  (see  FIG.  5   ) disposed at one end and the other end of a pressure roller  140  (described below) in the axial direction, and a pair of sprockets  74  (see  FIG.  9   ) disposed at a distance from each other in the depth direction of the apparatus. When any of these pairs of sprocket rotate, the chains  72  circulates in the direction of arrow C. The ends of the holding parts  68  for holding sheet members P are attached to the chains  72 . 
     Holding Part 
     As shown in  FIG.  3   , the holding parts  68  are attached to the chains  72  at both ends thereof and each include an attaching member  75  extending in the depth direction of the apparatus and grippers  76  attached to the attaching member  75 . 
     The holding parts  68  are disposed at predetermined intervals in the circumferential direction (circulating direction) of the chains  72 . 
     The grippers  76  are attached to the attaching member  75  at predetermined intervals in the depth direction of the apparatus. The grippers  76  hold the leading end of a sheet member P. More specifically, the grippers  76  have claws  76   a . The attaching member  75  has a contact portion  75   a  (see  FIG.  6   ) with which the claws  76   a  come into contact. 
     The grippers  76  hold a sheet member P by pinching the leading end of a sheet member P between the claws  76   a  and the contact portion  75   a . The grippers  76  are configured such that, for example, the claws  76   a  are urged against the contact portion  75   a  by springs or the like, and the claws  76   a  are brought toward and away from the contact portion  75   a  by the effect of cams or the like. 
     In this configuration, in the chain gripper  66 , when the chains  72  circulate in the direction of arrow C while the grippers  76  are holding the leading end of a sheet member P, the sheet member P is transported. The chain gripper  66  shown in  FIG.  9    transports the sheet member P, which has been transported by the transport rollers  64 , to the second transfer position NT, through the preheating part  102 , and then to the heating part  120 . 
     Heating Part 
     As shown in  FIG.  2   , the heating part  120  is located downstream of the preheating part  102  in the sheet transport direction. The heating part  120  includes a heating roller  130  that comes into contact with a sheet member P being transported to heat the sheet member P, a pressure roller  140  that presses the sheet member P toward the heating roller  130 , and a driven roller  150  that is rotated by the rotating heating roller  130 . 
     Heating Roller 
     As shown in  FIG.  2   , the heating roller  130  is disposed so as to come into contact with the top surface of a sheet member P being transported and extends in the depth direction of the apparatus such that the axis thereof extends in the depth direction of the apparatus. The heating roller  130  includes a cylindrical base member  132 , a rubber layer  134  formed so as to cover the overall circumference of the base member  132 , a separating layer  136  formed so as to cover the overall circumference of the rubber layer  134 , and a heater  138  accommodated in the base member  132 . The outside diameter of the outer circumferential surface of the separating layer  136  of the heating roller  130  is set to be, for example, 80 mm. 
     The base member  132  is an aluminum pipe having a thickness of, for example, 20 mm. Furthermore, the rubber layer  134  is made of silicone rubber and has a thickness of, for example, 6 mm. Furthermore, the separating layer  136  is made of a tetrafluoroethylene-perfluoroethylene copolymer (PFA resin) and has a thickness of, for example, 50 μm. 
     As shown in  FIG.  5   , shaft portions  139   a  extending in the depth direction of the apparatus are formed at both ends of the heating roller  130  in the depth direction of the apparatus, and support members  139   b  for supporting the corresponding shaft portions  139   a  are provided. With this structure, the heating roller  130  is rotatably supported by the support members  139 b at both ends thereof. 
     Driven Roller 
     As shown in  FIGS.  2  and  5   , the driven roller  150  is disposed on the opposite side of the heating roller  130  from the sheet member P being transported, so as to extend in the depth direction of the apparatus, such that the axis thereof extends in the depth direction of the apparatus. Furthermore, the driven roller  150  includes a cylindrical base member  152 , and a heater  154  accommodated in the base member  152 . The outside diameter of the outer circumferential surface of the base member  152  of the driven roller  150  is, for example, 50 mm. 
     The base member  152  is an aluminum pipe having a thickness of, for example, 10 mm. The driven roller  150  is rotatably supported by support members (not shown) at both ends thereof. 
     In this configuration, the driven roller  150  is driven and rotated by the heating roller  130 . The driven roller  150  heats the heating roller  130 . Because the heating roller  130  is heated by the driven roller  150 , and the heating roller  130  has the heater  138 , the surface temperature of the heating roller  130  is brought to a predetermined range of 180° C. to 200° C. 
     Pressure Roller 
     As shown in  FIGS.  2  and  5   , the pressure roller  140  is disposed so as to oppose the heating roller  130  with a sheet member P being transported therebetween, come into contact with the lower side of the sheet member P being transported, and extend in the depth direction of the apparatus such that the axis thereof extends the depth direction of the apparatus. The pressure roller  140  includes a cylindrical base member  142 , a rubber layer  144  formed so as to cover the base member  142 , a separating layer  146  formed so as to cover the rubber layer  144 , and a pair of shaft portions  148  (see  FIG.  5   ) formed at both ends in the depth direction of the apparatus. The outside diameter of the outer circumferential surface of the separating layer  146  of the pressure roller  140  is, for example, 225 mm. The outside diameter of the pressure roller  140  is larger than the outside diameter of the heating roller  130 . 
     The base member  142  is an aluminum pipe having a thickness of, for example, 20 mm. Furthermore, the rubber layer  144  is made of silicone rubber and has a thickness of, for example, 1 mm. Furthermore, the separating layer  146  is made of a tetrafluoroethylene-perfluoroethylene copolymer (PFA resin) and has a thickness of, for example, 50 μm. 
     Furthermore, as shown in  FIG.  6   , the pressure roller  140  has, in the outer circumferential surface thereof, a recess  140   a  extending in the depth direction of the apparatus. When a sheet member P passes between the pressure roller  140  and the heating roller  130 , the grippers  76  gripping the leading end of the sheet member P are stored in the recess  140   a.    
     As shown in  FIG.  5   , the shaft portions  148  are formed at both ends of the pressure roller  140  in the depth direction of the apparatus. The shaft portions  148  have a smaller diameter than the outer circumferential surface of the separating layer  146  of the pressure roller  140  and extend in the axial direction. 
     In this configuration, the pressure roller  140  receives a rotational force from a driving member (not shown) and rotates. The rotating pressure roller  140  rotates the heating roller  130 , and the rotating heating roller  130  rotates the driven roller  150 . As a result of the heating roller  130  and the pressure roller  140  nipping and transporting a sheet member P to which a toner image has been transferred, the toner image is fixed to the sheet member P. The heating roller  130  and the pressure roller  140  constitute a pair of transport portions  122 , which nip and transport the sheet member P while rotating and heat the sheet member P. 
     Other Configurations 
     As shown in  FIG.  5   , the heating part  120  includes support members  156  for supporting the pressure roller  140 , and urging members  158  for urging the pressure roller  140  toward the heating roller  130  through the support members  156 . The support members  156  are provided in pairs. The pair of support members  156  are disposed so as to rotatably support the shaft portions  148  of the pressure roller  140  from below. 
     The urging members  158  are compression springs provided in pairs. The urging members  158  are disposed on the opposite side of the support members  156  from the shaft portions  148 . 
     In this configuration, as a result of the pair of urging members  158  urging the pressure roller  140  toward the heating roller  130 , the pressure roller  140  presses the sheet member P toward the heating roller  130 . Then, as shown in  FIG.  2   , a portion of the heating roller  130  urged by the pressure roller  140  is deformed, forming a nip part N, where the heating roller  130  and the pressure roller  140  are in contact with each other. 
     Preheating Part 
     As shown in  FIG.  2   , the preheating part  102  is located downstream of the second transfer position NT (see  FIG.  9   ), where a toner image is transferred to a sheet member P, and upstream of the heating part  120  in the sheet transport direction. Furthermore, the preheating part  102  is disposed above a sheet member P being transported (i.e., the side to which a toner image is transferred). The preheating part  102  includes a reflection member  104 , multiple infrared heaters  106  (hereinbelow, the “heaters  106 ”), heating plates  114 , and a wire screen  112 . 
     Reflection Member 
     The reflection member  104  is made of an aluminum plate in the shape of a shallow box that is open on the side facing a sheet member P being transported. In other words, as viewed in the width direction, the reflection member  104  has a U shape with an opening facing a sheet member P being transported. In this exemplary embodiment, as viewed from above, the reflection member  104  covers, both in the depth direction and width direction of the apparatus, the sheet member P being transported. The reflection member  104  is an example of a reflection part. 
     As shown in  FIG.  1   , the heating plates  114  and the heaters  106  are disposed in the reflection member  104 , in this order from the side closer to a sheet member P being transported. The reflection member  104  has a reflection surface  104   a  that reflects infrared rays, which are heat rays radiated by the heaters  106 , toward the heating plates  114 . In other words, as shown in  FIG.  2   , the reflection surface  104   a , which reflects the infrared rays toward the heating plates  114 , is disposed on the opposite side of the heaters  106  and the heating plates  114  from the chains  72 . Thus, the reflection surface  104   a  serves as a radiation-direction changing member that changes the radiation direction of the infrared rays radiated from the heaters  106  in directions other than the direction of the heating plates  114  to the direction of the heating plates  114 . 
     Furthermore, as shown in  FIG.  1   , a reflection area (H 01  in  FIG.  1   ) in which the reflection surface  104   a  reflects the infrared rays toward the heating plates  114  is located in a space (S 01  in  FIG.  1   ) between the chains  72  in the depth direction of the apparatus. In other words, the chains  72  and the reflection area H 01  do not overlap each other in the depth direction of the apparatus. 
     Herein, “the space S 01  between the chains  72  in the depth direction of the apparatus” is an area between, in the depth direction of the apparatus, the portions of the chains  72  closest to the other chains  72 . 
     The reflection member  104  also has a pair of side plates  105  located on both sides of the heaters  106  and the heating plates  114  in the depth direction of the apparatus. As described above, the reflection member  104  accommodates the heating plates  114  and the heaters  106 ; that is, the lower edges of the side plates  105  are located below the heating plates  114  in the top-bottom direction of the apparatus. In other words, the lower edges of the side plates  105  project downward with respect to the heating plates  114  in the top-bottom direction of the apparatus. 
     Furthermore, the pair of side plates  105  have opposing faces  105   a  that face each other. The pair of opposing faces  105   a  are located within the space S 01  between the chains  72  in the depth direction of the apparatus. The opposing faces  105   a  are an example of side surfaces. 
     Heater 
     The heaters  106  are cylindrical infrared heaters extending in the depth direction of the apparatus. As shown in  FIG.  1   , the heaters  106  are opposed to the reflection surface  104   a  of the reflection member  104  in the top-bottom direction of the apparatus. As shown in  FIG.  2   , the heaters  106  are arranged side-by-side in the width direction of the apparatus. The heaters  106  are an example of radiation parts that radiate heat rays. 
     In this configuration, the heaters  106  that are energized by a power supply (not shown) radiate infrared rays having maximum spectral radiance at a wavelength of 3 μm to 5 μm. 
     Heating Plate 
     The heating plates  114  are made of, for example, stainless steel plates having a thickness of 1 mm and, as shown in  FIG.  2   , are located between the chains  72  and the heaters  106  as viewed in the depth direction of the apparatus. In other words, as viewed in the depth direction of the apparatus, the heaters  106  are disposed on the opposite side of the heating plates  114  from the chains  72 . The heating plates  114  are located at a distance of, for example, 30 mm, in the top-bottom direction of the apparatus, from the leading end of a sheet member P being transported. The heating plates  114  are an example of a heating part. 
     Furthermore, the heating plates  114  are arranged side-by-side in the width direction of the apparatus such that the place surfaces thereof face the sheet member P being transported. The thus-arranged heating plates  114  form a rectangular shape extending in the width direction of the apparatus, as viewed in the top-bottom direction of the apparatus. In this exemplary embodiment, as viewed from above, the heating plates  114  arranged without gaps cover a sheet member P being transported. In other words, the thus-arranged heating plates  114  occasionally heat the entirety of a sheet member P being transported at a time. 
     As shown in  FIG.  1   , the heating plates  114  are located within the space S 01  between the chains  72  in the depth direction of the apparatus. In other words, an area (H 02  in  FIG.  1   ) in which the heating plates  114  are arranged is located within the space S 01  between the chains  72  in the depth direction of the apparatus. In still other words, the chains  72  and the area H 02 , in which the heating plates  114  are arranged, do not overlap each other in the depth direction of the apparatus. 
     Furthermore, the heating plates  114  are located within an area (H 03  in  FIG.  1   ) in which the heaters  106  are arranged in the depth direction of the apparatus. In other words, the area H 02 , in which the heating plates  114  are arranged, is located within the area (H 03  in  FIG.  1   ) in which the heaters  106  are arranged, in the depth direction of the apparatus. The heating plates  114  have black coatings on the surfaces facing the heaters  106 . The areas H 02  and H 03  are located within the reflection area H 01  in the depth direction of the apparatus. 
     In this configuration, the heating plates  114  are heated by absorbing infrared rays radiated by the heaters  106  and infrared rays reflected by the reflection surface  104   a  and release heat. The heating plates  114  are heated to a temperature of, for example, 600° C. to 1175° C. and heat, in a non-contact manner, a sheet member P being transported. 
     In the width direction of the apparatus, the heating plates  114  are arranged in the same area as the area in which the heaters  106  are arranged. 
     Wire Screen 
     As shown in  FIG.  1   , the wire screen  112  is fixed to the edge of the reflection member  104  with fixing members (not shown) to divide the inside of the reflection member  104  from the outside. The wire screen  112  prevents contact between the heating plates  114  and the sheet member P being transported. 
     Blowing Unit 
     As shown in  FIG.  2   , the blowing unit  170  is disposed so as to oppose the preheating part  102  in the top-bottom direction of the apparatus, and the sheet member P being transported passes between the blowing unit  170  and the preheating part  102 . As shown in  FIG.  4   , the blowing unit  170  includes multiple fans  172  arranged in the width direction and the depth direction of the apparatus. 
     In this configuration, the orientation of the sheet member P being transported is stabilized by the fans  172  blowing air at the sheet member P. The fans  172  serve as orientation stabilizers for stabilizing the orientation of the sheet member P being transported. 
     Heat Shielding Member 
     The heat shielding members  108  are provided in pairs and are made of, for example, stainless steel plates having a thickness of 1 mm. As shown in  FIG.  1   , the heat shielding members  108  are opposed to the chains  72  in the top-bottom direction of the apparatus, as viewed in the width direction of the apparatus. The heat shielding members  108  are an example of heat shielding parts. 
     More specifically, as shown in  FIG.  2   , the heat shielding members  108  are disposed at least in the area in which the preheating part  102  is disposed, in the width direction of the apparatus. Furthermore, as shown in  FIG.  1   , the heat shielding members  108  have an L shape as viewed in the width direction of the apparatus and each include an opposing plate  108   a  that opposes the corresponding chain  72  in the top-bottom direction of the apparatus and a side plate  108   b  that covers the corresponding chain  72  from the outside in the depth direction of the apparatus. The top-bottom direction of the apparatus is an example of an intersecting direction. 
     The upward-facing surfaces of the opposing plates  108   a  are uncoated and have an average surface roughness Ra (JIS B 0031) of 1 μm or less. Furthermore, in the depth direction of the apparatus, the heat shielding members  108  are located on the outer sides of the area H 02 , in which the heating plates  114  are arranged. In other words, the heat shielding members  108  and the area H 02 , in which the heating plates  114  are arranged, do not overlap each other in the depth direction of the apparatus. 
     In this configuration, the heat shielding members  108  block the heat radiated from the heating plates  114  of the preheating part  102  and transferred to the chains  72 . 
     Effect of Relevant Part Configuration 
     Next, the effect of the fixing device  100  will be described in comparison with that of a fixing device  600  according to a comparative example. First, the configuration of the fixing device  600  according to the comparative example will be described below, focusing on the difference from the fixing device  100 . 
     Fixing Device  600   
     As shown in  FIG.  10   , the fixing device  600  includes a preheating part  602  that heats, in a non-contact manner, a sheet member P being transported, the chains  72 , and the holding parts  68 . The fixing device  600  also includes the heating part  120  (see  FIG.  2   ) that comes into contact with the sheet member P to apply heat and pressure thereto, and the blowing unit  170 . The fixing device  600  does not have heat shielding members that block the heat radiated from heating plates  614  and transferred to the chains  72 . 
     Preheating Part  602   
     As shown in  FIG.  10   , the preheating part  602  includes a reflection member  604 , multiple infrared heaters  606  (hereinbelow, “heaters  606 ”), the heating plates  614 , and a wire screen  612 . 
     The reflection member  604  is made of an aluminum plate in the shape of a shallow box that is open on the side facing a sheet member P being transported. The reflection member  604  has a reflection surface  604   a  that reflects infrared rays, which are heat rays radiated by the heaters  606 , toward the heating plates  614 . 
     In the depth direction of the apparatus, a reflection area (H 11  in  FIG.  10   ) in which the reflection surface  604   a  reflect the infrared rays toward the heating plates  614  is not located within the space S 01  between the chains  72 , but extends beyond the space S 01  between the chains  72 . 
     The reflection member  604  also has a pair of side plates  605  located on both sides of the heaters  606  and the heating plates  614  in the depth direction of the apparatus. The lower edges of the side plates  605  are located below the heating plates  614  in the top-bottom direction of the apparatus. 
     Furthermore, the pair of side plates  605  have opposing faces  605   a  that face each other. The pair of opposing faces  605   a  are not disposed in the space S 01  between the chains  72  in the depth direction of the apparatus. 
     The heaters  606  are cylindrical infrared heaters extending in the depth direction of the apparatus. As shown in  FIG.  10   , the heaters  606  are opposed to the reflection surface  604   a  of the reflection member  604  in the top-bottom direction of the apparatus. Furthermore, the heaters  606  are arranged side-by-side in the width direction of the apparatus. 
     The heating plates  614  are arranged side-by-side in the width direction of the apparatus so as to face a sheet member P being transported. The thus-arranged heating plates  614  form a rectangular shape extending in the width direction of the apparatus, as viewed in the top-bottom direction of the apparatus. An area (H 12  in  FIG.  10   ) in which the heating plates  614  are arranged is not located within the space S 01  between the chains  72  in the depth direction of the apparatus, but extends beyond the space S 01  between the chains  72 . In other words, the heating plates  614  and the chains  72  overlap each other in the depth direction of the apparatus. In still other words, the chains  72  and the heating plates  614  face each other in the top-bottom direction of the apparatus, as viewed in the width direction of the apparatus. 
     Furthermore, in the depth direction of the apparatus, the area H 12 , in which the heating plates  614  are arranged, is located within an area (H 13  in  FIG.  10   ) in which the heaters  606  are arranged. 
     Furthermore, the wire screen  612  is fixed to the edge of the reflection member  604  (not shown) with fixing members (not shown) to divide the inside of the reflection member  604  from the outside, as shown in  FIG.  10   . 
     Effect of Fixing Devices  100  and  600   
     When the fixing devices  100  and  600  are not operating, the heaters  106  and  606  are not energized, and the chains  72  are stopped. The fans  172  of the blowing unit  170  are stopped. 
     When an image forming operation is started, the chains  72  start to circulate and transport a sheet member P to which a toner image has been transferred. Furthermore, the fans  172  are activated to blow air to the sheet member P from below, so that the sheet surfaces of the sheet member P face upward and downward. 
     Furthermore, in the fixing devices  100  and  600  shown in  FIG.  1 ,  10   , the heaters  106  and  606  of the preheating parts  102  and  602  are energized. The heating plates  114  and  614  are heated by absorbing infrared rays radiated by the energized heaters  106  and  606  and infrared rays reflected by the reflection surfaces  104   a  and  604   a  and release the heat. Then, the heated heating plates  114  and  614  heat, in a non-contact manner, a sheet member P transported by the circulating chains  72 . As a result of the sheet member P being heated, the toner constituting the toner image on the sheet member P is softened. 
     Furthermore, in the heating part  120  shown in  FIG.  2   , the heating roller  130  and the pressure roller  140  nip and transport the sheet member P that has been heated by the heating plates  114  and  614  of the preheating parts  102  and  602  to fix the toner image to the sheet member P. The sheet member P, to which the toner image has been fixed, is discharged outside the apparatus through the cooling unit  90  (see  FIG.  9   ). 
     In the preheating part  602  of the fixing device  600  according to the comparative example, as shown in  FIG.  10   , the area H 12 , in which the heating plates  614  are arranged, is not located within the space S 01  between the chains  72 , but extends beyond the space S 01  between the chains  72  in the depth direction of the apparatus. Hence, the heat radiated by the heating plates  614  heats the chains  72 , causing the chains  72  to elongate in the circulating direction. If the amount of elongation of one chain  72  differs from that of the other, the sheet member P being transported is skewed with respect to the transport direction and is nipped between the heating roller  130  and the pressure roller  140  in this state. This may crease the sheet member P. 
     In contrast, as shown in  FIG.  1   , in the preheating part  102  of the fixing device  100  according to this exemplary embodiment, the area H 02 , in which the heating plates  114  are arranged, is located within the space S 01  between the chains  72  in the depth direction of the apparatus. Hence, compared with a configuration using the fixing device  600 , the chains  72  are prevented from being heated by the heating plates  114 . As a result of an increase in temperature of the chains  72  being prevented, skew of a sheet member P being transported with respect to the transport direction is prevented, compared with the configuration using the fixing device  600 . Thus, creases in the sheet member P nipped between the heating roller  130  and the pressure roller  140  is prevented. 
     As described above, in the fixing device  100 , the area H 02 , in which the heating plates  114  are arranged, is located within the space S 01  between the chains  72  in the depth direction of the apparatus. Hence, compared with the configuration using the fixing device  600 , the chains  72  are prevented from being heated by the heating plates  114 . 
     Furthermore, in the fixing device  100 , the heating plates  114  having plate surfaces facing a sheet member P being transported absorb infrared rays radiated by the heaters  106  and release heat to heat the sheet member P. Hence, for example, compared with a configuration using the heating plates  114  with corrugated plate surfaces, difference in distance between the heating plates  114  and the sheet member P at different positions is prevented, and thus, unevenness in the temperature of the heated sheet member P is prevented. 
     Furthermore, in the fixing device  100 , the area H 02 , in which the heating plates  114  are arranged, is located within the area H 03 , in which the heaters  106  are arranged, in the depth direction of the apparatus. Hence, compared with a configuration in which the area in which the heating plates are arranged extends beyond the area in which the heaters are arranged in the depth direction of the apparatus, unevenness in the temperature of the heating plates  114  is prevented. 
     Furthermore, in the fixing device  100 , because the unevenness in the temperature of the heating plates  114  is prevented, the overall heating plates  114  uniformly absorb the infrared rays. Hence, compared with a configuration in which the area in which the heating plates are arranged extends beyond the area in which the heaters are arranged in the depth direction of the apparatus, the temperature of the overall heating plates  114  uniformly increases. 
     Furthermore, in the fixing device  100 , the reflection area H 01 , in which the reflection surface  104   a  reflects the infrared rays toward the heating plates  114 , is located within the space S 01  between the chains  72  in the depth direction of the apparatus. Hence, compared with a configuration in which, as in the fixing device  600 , the reflection area H 11  of the reflection surface  604   a  is not located within the space S 01  between the chains  72 , but extends beyond the space S 01  between the chains  72 , the chains  72  are prevented from being heated by the infrared rays reflected from the reflection surface  104   a.    
     Furthermore, in the fixing device  100 , the pair of opposing faces  105   a  formed in the reflection member  104  are located within the space S 01  between the chains  72 . Hence, compared with a configuration in which, as in the fixing device  600 , the pair of opposing faces  605   a  are not located within the space S 01  between the chains  72 , the heat inside the reflection member  104  is not radiated toward the chains  72 , and thus, an increase in the temperature of the chains  72  is prevented. 
     Furthermore, in the fixing device  100 , the lower edges of the side plates  105  are located below the heating plates  114  in the top-bottom direction of the apparatus. Hence, compared with a configuration in which the lower edges of the side plates are located above the heating plates, the heat inside the reflection member  104  is not radiated toward the chains  72 , and thus, an increase in the temperature of the chains  72  is prevented. 
     Furthermore, in the fixing device  100 , the heat shielding members  108  with the opposing plates  108   a  facing the chains  72  in the top-bottom direction of the apparatus are arranged on the outer side of the area H 02 , in which the heating plates  114  are arranged, in the depth direction of the apparatus. Hence, compared with a configuration in which the heat shielding members extend to the area in which the heating plates are arranged in the depth direction of the apparatus, the heat shielding members  108  are prevented from being heated, and thus, an increase in the temperature of the chains  72  is prevented. 
     Furthermore, in the fixing device  100 , the upward-facing surfaces of the opposing plates  108   a  of the heat shielding members  108  are not coated and have an average surface roughness Ra (JIS B 0031) of 1 μm or less. Hence, compared with a configuration in which the upward-facing surfaces of the opposing plates  108   a  have an average surface roughness Ra of more than 1 μm, the heat radiated by the heating plates  114  is effectively reflected, and thus, an increase in the temperature of the chains  72  is prevented. 
     Furthermore, in the fixing device  100 , compared with the configuration using the fixing device  600 , skew of a sheet member P being transported with respect to the transport direction is prevented. Hence, creases in the sheet member P caused by the sheet member P being nipped between the heating roller  130  and the pressure roller  140  in a skewed state is prevented. 
     Furthermore, in the image forming apparatus  10 , compared with the configuration using the fixing device  600 , creases in the sheet member P is prevented. Hence, a decrease in the quality of an output image is prevented. 
     Second Exemplary Embodiment 
     An example of a fixing device and an example of an image forming apparatus according to a second exemplary embodiment of the present disclosure will be described with reference to  FIGS.  11  and  12   . The second exemplary embodiment will be described below, focusing on the difference from the first exemplary embodiment. 
     As shown in  FIG.  12   , a fixing device  300  of an image forming apparatus  210  according to the second exemplary embodiment includes a preheating part  302  that heats, in a non-contact manner, a sheet member P being transported, the chains  72 , and the holding parts  68 . The fixing device  300  also includes the heating part  120  that comes into contact with the sheet member P to apply heat and pressure, the blowing unit  170 , and the heat shielding members  108  that block the heat radiated from the preheating part  302  and transferred to the chains  72 . 
     Preheating Part  302   
     As shown in  FIG.  11   , the preheating part  302  includes a reflection member  304 , multiple infrared heaters  306  (hereinbelow, “heaters  306 ”), and a wire screen  312 . 
     The reflection member  304  is made of an aluminum plate in the shape of a shallow box that is open on the side facing a sheet member P being transported. The reflection member  304  has a reflection surface  304   a  that reflects infrared rays radiated by filaments  306   b  (described below) of the heaters  306 . 
     In the depth direction of the apparatus, a reflection area (H 31  in  FIG.  11   ) in which the reflection surface  304   a  reflects the infrared rays is located within the space S 01  between the chains  72 . 
     The reflection member  304  has a pair of side plates  305  located on both sides of the heaters  306  in the depth direction of the apparatus. The lower edges of the side plates  305  are located below the heaters  306  in the top-bottom direction of the apparatus. 
     Furthermore, the pair of side plates  305  have opposing faces  305   a  that face each other. The pair of opposing faces  305   a  are disposed within the space S 01  between the chains  72  in the depth direction of the apparatus. The opposing faces  305   a  are an example of side surfaces. 
     The heaters  306  are cylindrical infrared heaters and are located at a distance of, for example, 30 mm, in the top-bottom direction, from the leading end of a sheet member P being transported. Furthermore, as shown in  FIG.  11   , the heaters  306  include cylindrical silica tubes  306   a  and the filaments  306   b , which are arranged in the silica tubes  306   a  and radiate infrared rays. The silica tubes  306   a  have black coatings on the surfaces. The silica tubes  306   a  are an example of the heating part. 
     An area in which the silica tubes  306   a  are arranged (H 33  in  FIG.  11   ) is located within the space S 01  between the chains  72  in the depth direction of the apparatus. 
     Furthermore, as shown in  FIG.  11   , the wire screen  312  is fixed to the edge of the reflection member  304  with fixing members (not shown) to divide the inside of the reflection member  304  from the outside. 
     Effect 
     In the fixing device  300  shown in  FIG.  11   , the filaments  306   b  of the heaters  306  are energized. The silica tubes  306   a  are heated by absorbing the infrared rays radiated by the energized filaments  306   b  and release heat. The heated silica tubes  306   a  heat, in a non-contact manner from above, the sheet member P transported by the circulating chains  72 . As a result of the sheet member P being heated, the toner constituting the toner image on the sheet member P is softened. 
     Other effects are the same as those in the first exemplary embodiment, except for the effect obtained by the presence of the heating plates  114 . 
     Although specific exemplary embodiments of the present disclosure have been described in detail above, it is obvious to those skilled in the art that the present disclosure is not limited to the above-described exemplary embodiments, and various modifications, changes, improvements are possible within the scope of the present disclosure. For example, although not specifically described in the above-described exemplary embodiments, for example, other heating devices, such as a ceramic heater, a halogen heater, and heating wires, may be used as a heating part for heating the sheet member P. 
     In the first exemplary embodiment, the heating plates  114  are plate members having plate surfaces facing a sheet member P being transported. However, the heating plates  114  may be corrugated. In that case, the effect obtained by the plate surfaces facing a sheet member P being transported is not obtained. 
     Furthermore, although not specifically described in the above-described exemplary embodiments, the opposing faces  105   a  and  305   a  may reflect heat. This prevents a decrease in temperature in the reflection members  104  and  304 , and the sheet member P being transported is effectively heated. 
     Furthermore, although the circulating parts have been the chains  72  in the above-described exemplary embodiments, the circulating parts only need to be endless, and thus, may be wires or the like. 
     In the first exemplary embodiment, although the heating plates  114  are located within the area H 03  in the depth direction of the apparatus, the heating plates  114  do not need to be located within the area H 03 . However, in that case, the effect obtained by the heating plates  114  being located within the area H 03  is not obtained. 
     The foregoing description of the exemplary embodiments of the present disclosure has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure to the precise forms disclosed. Obviously, many modifications and variations will be apparent to practitioners skilled in the art. The embodiments were chosen and described in order to best explain the principles of the disclosure and its practical applications, thereby enabling others skilled in the art to understand the disclosure for various embodiments and with the various modifications as are suited to the particular use contemplated. It is intended that the scope of the disclosure be defined by the following claims and their equivalents.