IMAGING SYSTEM WITH TILTING BELT ROLLER AND GLOSS TREATMENT DEVICE BACKGROUND ART [0001] An imaging apparatus may be provided with a gloss treatment device for imparting gloss to an image formed on a print medium. The gloss treatment device heats and melts a toner image on the print medium conveyed by a conveyor belt and resolidifies the toner image by way of a cooling device. Then, the print medium is peeled off from the conveyor belt, so as to create a smooth image surface and impart gloss to the image. BRIEF DESCRIPTION OF DRAWINGS [0002] FIG.1 is a schematic view of an example imaging apparatus. FIG. 2 is a side view schematically illustrating an example gloss treatment device. FIG. 3 is a front view of a belt roller of the example gloss treatment device, illustrating the belt roller supported on support devices. FIG.4 is a side view of the belt roller illustrated in FIG.3. FIG. 5A is a diagram illustrating a portion of a belt roller including an example contact surface. FIG. 5B is a diagram illustrating a portion of a belt roller including another example contact surface. FIG. 6 is a diagram illustrating the example belt roller tilted in a first tilt position. FIG. 7 is a diagram illustrating the belt roller tilted in a second tilt position. FIG. 8 is a schematic diagram of the belt roller, a heating roller and an endless belt of the gloss treatment device, illustrating a moving direction of the endless belt. FIG.9 is a plan view of the example gloss treatment device, illustrating a first operational state of the endless belt. FIG. 10 is a plan view of the example gloss treatment device, illustrating a second operational state of the endless belt. FIG. 11 is a graph illustrating a change over time in the moving distances of the endless belt and the belt roller. FIG. 12A is a diagram illustrating a support device, according to another example gloss treatment device. FIG.12B is a diagram illustrating another example support device. FIG.12C is a diagram illustrating yet another example support device. DETAILED DESCRIPTION [0003] In the following description, with reference to the drawings, the same reference numbers are assigned to the same components or to similar components having the same function, and overlapping description is omitted. [0004] An example imaging apparatus will be described with reference to the drawings. The imaging apparatus includes an endless belt that is supported on a belt roller, for example in a gloss treatment device of the imaging apparatus. The endless belt may shift in a width direction as the endless belt rotates, so as to move along the belt roller. When the endless belt contacts an end portion of the belt roller, the belt roller is tilted so as to cause the endless belt to shift back in the opposite direction. [0005] FIG. 1 is a diagram schematically illustrating an example imaging apparatus 1 that forms a color image by using respective colors of cyan, magenta, yellow, and black, designated by the letters “C”, “M”, “Y”, and “K”, respectively. The imaging apparatus 1 includes a conveying device 10 which conveys a sheet (e.g., a paper sheet) 5 corresponding to a print medium, a plurality of photoreceptors 40C, 40M, 40Y, and 40K, each having a surface to form an electrostatic latent image, a plurality of developing devices 20C, 20M, 20Y, and 20K which develop the respective electrostatic latent images to form toner images, a transfer device 30 onto which the toner images are layered to form a single composite toner image (or layered toner image) to be subsequently transferred to the sheet 5, a fixing device 50 which fixes the composite (or layered) toner image to the sheet 5, a discharge device 60 which discharges the sheet 5, a gloss treatment device 70, and a controller 80 that controls the operation of the imaging apparatus 1. Hereinafter, a "developing device 20" refers to any one of the developing devices 20C, 20M, 20Y, and 20K, and a "photoreceptor 40" refers to any one of the photoreceptors 40C, 40M, 40Y, and 40K. [0006] The conveying device 10 conveys the sheet 5 corresponding to a print medium on which an image is to be formed, along a conveyance route 12. The sheet 5 is initially accommodated in a cassette 7 in a stacked state and is picked up and conveyed by a feeding roller 11. The conveying device 10 conveys the sheet 5 to reach a transfer area 13 along the conveyance route 12 at a timing in which the toner image to be transferred to the sheet 5 reaches the transfer area 13. [0007] Four developing devices 20C, 20M, 20Y, and 20K are provided for the respective colors of cyan, magenta, yellow, and black. Each developing device 20 includes a developing roller 110 which transfers a toner to an adjacent one of the photoreceptors 40C, 40M, 40Y, and 40K. In the developing device 20, a two-component developer containing a toner and a carrier is used as a developer. Namely, in the developing device 20, the toner and the carrier are adjusted to a targeted mixing ratio and are further mixed so that the toner is dispersed to achieve an optimal charge amount in the developer. This developer is carried on the developing roller 110. Then, when the developer is conveyed to a developing area facing the photoreceptor 40 with the rotation of the developing roller 110, the toner contained in the developer carried on the developing roller 110 is transferred to the electrostatic latent image formed on the peripheral surface of the adjacent photoreceptor 40 so that the electrostatic latent image is developed into a toner image. [0008] The transfer device 30 conveys the toner image formed by the developing device 20 to the transfer area 13. The transfer device 30 includes a transfer belt 31 to convey the toner images developed on the respective photoreceptors 40C, 40M, 40Y, and 40K, a suspension roller 34 that supports the transfer belt 31, idler rollers 35 and 36, a drive roller 37 which drives the transfer belt 31, primary transfer rollers 32C, 32M, 32Y, and 32K located adjacent the photoreceptors 40C, 40M, 40Y, and 40K, respectively, and a secondary transfer roller 33 located adjacent the drive roller 37. The transfer belt 31 extends between the primary transfer rollers 32C, 32M, 32Y, and 32K and the photoreceptors 40C, 40M, 40Y, and 40K, to carry out a primary transfer by which the individual toner images developed are layered onto the transfer belt 31 to form a composite toner image. The transfer belt 31 further extends between the secondary transfer roller 33 and the drive roller 37 to carry out the secondary transfer by which the composite toner image is transferred to the sheet 5 at the transfer area 13. [0009] The photoreceptors 40C, 40M, 40Y, and 40K may also be referred to as electrostatic latent image carriers, photoconductor drums, or the like. The four photoreceptors 40C, 40M, 40Y, and 40K are provided for respective colors of cyan, magenta, yellow, and black. The photoreceptors 40C, 40M, 40Y, and 40K are respectively arranged along the moving direction of the transfer belt 31. The developing device 20, a charging device 41, an exposure unit (or device) 42, and a cleaning device 43 are provided adjacent the photoreceptor 40. [0010] The charging device 41 charges the surface of the photoreceptor 40 to a predetermined potential. The exposure unit 42 exposes the surface of the photoreceptor 40 having been charged by the charging device 41, according to an image to be formed on the sheet 5. Consequently, a potential of a portion exposed by the exposure unit 42 on the surface of the photoreceptor 40, changes so that the electrostatic latent image is formed. The developing devices 20C, 20M, 20Y, and 20K form respective toner images by developing the electrostatic latent images formed on the respective photoreceptors 40C, 40M, 40Y, and 40K with the toners supplied from toner tanks 18C, 18M, 18Y, and 18K. The respective toner tanks 18C, 18M, 18Y, and 18K contain toners of the colors of cyan, magenta, yellow, and black, respectively. The cleaning device 43 collects the toner remaining on the photoreceptor 40 after the toner image formed on the photoreceptor 40 has been primarily transferred to the transfer belt 31. [0011] The fixing device 50 conveys the sheet 5 to pass through a fixing nip area for heating and pressing the sheet so that the composite toner image having been transferred onto the sheet 5, is attached and fixed to the sheet 5. The fixing device 50 includes a heating roller 52 which heats the sheet 5 and a pressing roller 54 which rotationally drives the heating roller 52 in a pressed state. The heating roller 52 and the pressing roller 54 are each formed in a substantially cylindrical shape and the heating roller 52 includes a heat source such as a halogen lamp therein. A fixing nip area which is a contact area is provided between the heating roller 52 and the pressing roller 54, and the toner image is melted and fixed to the sheet 5 when the sheet 5 is conveyed through the fixing nip area. [0012] The discharge device 60 includes discharge rollers 62 and 64 which discharge the sheet 5 to which the toner image is fixed by the fixing device 50 to the outside of the apparatus. [0013] The gloss treatment device 70 imparts gloss to the fixed toner image on the sheet 5. The gloss treatment device 70 is disposed on the downstream side of the discharge device 60 in the conveying direction of the sheet 5. In other examples, the gloss treatment device 70 may be disposed between the fixing device 50 and the discharge device 60 and may be attached to the discharge device 60. The gloss treatment device 70 performs a remelting process, a cooling process, and a peeling process on the composite toner image fixed to the sheet 5. [0014] The imaging apparatus 1 further includes a controller (e.g., control unit) 80. The controller 80 may be a computer including a processor, a storage unit (or storage device), an input device, a display device, and the like, so as to control the operation of the imaging apparatus 1. The storage unit of the control unit 80 may store a data and instructions that are executable by the processor to control various processes performed in the imaging apparatus 1. [0015] Examples of the gloss treatment device 70 will be described. With reference to FIG.2, the gloss treatment device 70 includes an endless belt 71, a belt roller 72, a heating roller 73, a pressing roller 74, and a cooling device 75. [0016] The endless belt 71 extends between the belt roller 72 and the heating roller 73. The endless belt 71 rotates while supporting the sheet 5 on the surface thereof so as to convey the sheet 5. The belt roller 72 has a substantially cylindrical shape and is supported so as to be rotatable around its axis. The belt roller 72 tensions the endless belt 71 from the inside so that the endless belt 71 is suspended thereon. [0017] The heating roller 73 is provided at the upstream position of the belt roller 72 in the conveying direction of the sheet 5 so as to extend substantially parallel to the belt roller 72. The heating roller 73 tensions the endless belt 71 from the inside so as to suspend the endless belt 71 along with the belt roller 72. The heating roller 73 includes a heat source such as a halogen lamp thereinside and heats the composite toner image fixed to the sheet 5. [0018] The pressing roller 74 has a substantially cylindrical shape and is positioned to face the heating roller 73 with the endless belt 71 interposed therebetween. A fusing nip portion is formed between the heating roller 73 and the pressing roller 74. When the sheet 5 passes through this fusing nip portion, the composite toner image is heated and pressed so that the composite toner image is remelted, as part of a remelting process. [0019] The heating roller 73 is a drive roller which rotates around an axis via a drive force of a motor and the belt roller 72 and the pressing roller 74 are driven rollers which rotate in a following manner in accordance with the rotation of the endless belt 71. In other examples, the belt roller 72 may be a drive roller which rotates around an axis via a drive force of a motor. [0020] The cooling device 75 is provided between the belt roller 72 and the heating roller 73 in the conveying direction of the sheet 5. The cooling device 75 is, for example, a heat sink, a cooling fan, a heat pipe, or a Peltier element. In a cooling process, the cooling device 75 cools the sheet 5 conveyed by the endless belt 71 so as to solidify the composite toner image. In a peeling process, the sheet 5 cooled by the cooling device 75 is conveyed to a position facing the belt roller 72 and is peeled off from the endless belt 71. Accordingly, in the gloss treatment device 70, the composite toner image is remelted and solidified so that the surface shape of the endless belt 71 is transferred to the composite toner image and the smoothness of the composite toner image is enhanced. Consequently, gloss is imparted to the composite toner image. [0021] Additionally, the gloss treatment device 70 may further include a clear toner supply unit (or clear toner supply device) which is provided at the upstream position of the heating roller 73 in the conveying direction of the sheet 5 so as to supply a clear toner. The clear toner may be applied to the composite toner image fixed to the sheet 5, to further enhance the glossiness of the composite toner image. [0022] Incidentally, when the endless belt 71 is moved in a circulating manner by the belt roller 72 and the heating roller 73, the endless belt 71 may meander in the width direction (the longitudinal direction of the belt roller 72) due to a misalignment or the like of the belt roller 72 and the heating roller 73. When the endless belt 71 meanders, opposite edges (or edge portions) 71A and 71B of the endless belt 71 in the width direction may contact a frame or the like of the gloss treatment device 70 which may in turn damage the endless belt 71. In response to the movement of the endless belt 71, the belt roller 72 is tilted so as to suppress the meandering or shifting of the endless belt 71. [0023] With reference to FIGS. 3 and 4, the belt roller 72 will be described. In the following description, the longitudinal direction of the belt roller 72 is referred to as the "left and right direction", the vertical direction of the imaging apparatus 1 is referred to as the "up and down direction", and a direction that is orthogonal to the left and right direction and the up and down direction is referred to as the "front and rear direction". [0024] As illustrated in FIG. 3, the belt roller 72 has a substantially cylindrical shape and includes a first end (or first end portion) 72A and a second end (or second end portion) 72B opposite each other in the longitudinal direction (left and right direction). The first end portion 72A is a right end portion of the belt roller 72 and the second end portion 72B is a left end portion of the belt roller 72. The outer peripheral surface of the belt roller 72 includes a first contact surface 91 which is adjacent to the first end portion 72A, a second contact surface 92 which is adjacent to the second end portion 72B, and a center contact surface 93 which extends in the longitudinal direction between the first contact surface 91 and the second contact surface 92. The length of the center contact surface 93 in the left and right direction may be formed to be longer than the width of the endless belt 71 in the left and right direction. [0025] The center contact surface 93 has a substantially constant diameter in the longitudinal direction of the belt roller 72. The diameter of the first contact surface 91 increases toward the first end portion 72A and the diameter of the second contact surface 92 increases toward the second end portion 72B. That is, the diameters of the first contact surface 91 and the second contact surface 92 increase toward the outside (toward the ends) of the belt roller 72. Additionally, in order to make the outer shape of the belt roller 72 smooth, the first contact surface 91 and the center contact surface 93 may have substantially the same diameter in the boundary portion between the first contact surface 91 and the center contact surface 93 and the second contact surface 92 and the center contact surface 93 may have substantially the same diameter in the boundary portion between the second contact surface 92 and the center contact surface 93. Namely, the diameter of the first contact surface 91 taken adjacent the center contact surface may be the same as the diameter of the center contact surface, so that the increase in diameter from the center contact surface to an end of the first contact surface 91 is gradual. Similarly, the diameter of the second contact surface 92 taken adjacent the center contact surface may be the same as the diameter of the center contact surface. Thus, the first contact surface 91 and the second contact surface 92 have maximum diameters which are greater than the diameter of the center contact surface 93. [0026] In some examples, the first contact surface 91 and the second contact surface 92 may have friction coefficients which are greater than the friction coefficient of the center contact surface 93. For example, the center contact surface 93 may have a friction coefficient of 0.2 or less and the first contact surface 91 and the second contact surface 92 may have friction coefficients of 0.3 or more. [0027] In order to increase the friction coefficients of the first contact surface 91 and the second contact surface 92, for example, the first contact surface 91 and the second contact surface 92 may be formed of materials different from that of the center contact surface 93. For example, the center contact surface 93 may be formed of metal, and the first contact surface 91 and the second contact surface 92 may be formed of an elastic body such as urethane or silicon. [0028] In another example, as illustrated in FIG. 5A, the first contact surface 91 and the second contact surface 92 may be provided with a spiral groove 95 for increasing the friction coefficient. Further, as illustrated in FIG. 5B, the groove 95 may be formed in a lattice shape. As still another example, the first contact surface 91 and the second contact surface 92 may be provided with a spiral or dotted protuberance pattern to increase the friction coefficient of the contact surfaces 91 and 92. [0029] Additionally, in examples in which the diameters of the first contact surface 91 and the second contact surface 92 increase toward the outside of the belt roller 72, the friction coefficient may be substantially the same in the first contact surface 91, the second contact surface 92, and the center contact surface 93. [0030] According to examples, the gloss treatment device 70 may further include a support device 100. This support device 100 supports the belt roller 72 so as to be movable in the left and right direction (the longitudinal direction). This support device 100 tilts the belt roller 72 when the belt roller 72 moves in the left and right direction. [0031] As illustrated in FIG. 3, the support device 100 includes a pair of left and right support frames 101 and 111 and a pair of left and right rotation arms 102 and 112. The pair of support frames 101 and 111 are provided adjacent to the first end portion 72A and the second end portion 72B of the belt roller 72. As illustrated in FIG. 4, the pair of support frames 101 and 111 have a U-shaped (substantially U-shaped) cross-sectional shape and are provided to at least partially surround the first end portion 72A and the second end portion 72B. [0032] The pair of support frames 101 and 111 are attached to rails extending in the front and rear direction of the gloss treatment device 70 so as to slide independently (individually slidable) along the rails in the front and rear direction. A spring 105 connects each one of the support frames 101 and 111 to a corresponding one of the rails. Each spring 105 is connected at one end to a corresponding one of the support frames 101 and 111, and an opposite end of each spring 105 is coupled to the rail side. As illustrated in FIG. 2, the springs 105 may be connected to the respective support frames 101 and 111, respectively at a position lower than a virtual line 70L intersecting the belt roller 72 and the heating roller 73. This spring 105 applies a tension to the endless belt 71 by urging the pair of support frames 101 and 111 backward. [0033] The pair of support frames 101 and 111 are respectively provided with rotation shafts 101c and 111c extending in the front and rear direction. The base portion of the rotation arm 102 (the first rotation arm) is connected to the rotation shaft 101c of the support frame 101 so as to be rotatable around the rotation shaft 101c. The front end portion of the rotation arm 102 is connected to the support member 103 and supports the support member 103 in a suspended state. The support member 103 axially supports the first end portion 72A through a bearing 104. That is, the rotation arm 102 supports the first end portion 72A in a suspended state. [0034] Similarly, the base portion of the rotation arm 112 (the second rotation arm) is connected to the rotation shaft 111c of the support frame 111 so as to be rotatable around the rotation shaft 111c. The front end portion of the rotation arm 112 is connected to the support member 113 and supports the support member 113 in a suspended state. The support member 113 axially supports the second end portion 72B through the bearing 104. That is, the rotation arm 112 supports the second end portion 72B in a suspended state. [0035] As described above, since the pair of rotation arms 102 and 112 rotate around the rotation shafts 101c and 111c, the belt roller 72 is supported to be movable in the left and right direction. Further, as illustrated in FIG. 3, when the belt roller 72 is disposed at the center position in the left and right direction, the pair of rotation arms 102 and 112 extend away from each other downwardly. Accordingly, the support device 100 can tilt the belt roller 72 when the belt roller 72 moves in the left and right direction. [0036] For example, as illustrated in FIG. 6, when the belt roller 72 moves to the left side in the longitudinal direction (the direction from the first end portion 72A to the second end portion 72B), the pair of rotation arms 102 and 112 rotate in a clockwise rotation direction around the respective rotation shafts 101c and 111c. Consequently, the second end portion 72B is disposed at a position higher than the first end portion 72A and the belt roller 72 is supported in a first tilt position in which the belt roller 72 is inclined upwardly toward the second end portion 72B, so that the second end portion 72B is positioned higher than the first end portion 72A. The first tilt position may also be referred to herein as a first position, a first state, a first posture or a first configuration of the belt roller 72. [0037] In contrast, as illustrated in FIG.7, when the belt roller 72 moves to the right side in the longitudinal direction (the direction from the second end portion 72B to the first end portion 72A), the pair of rotation arms 102 and 112 rotate in a counterclockwise rotation direction around their respective rotation shafts 101c and 111c. Consequently, the first end portion 72A is disposed at a position higher than the second end portion 72B and the belt roller 72 is supported in a second tilt position in which the belt roller 72 is inclined upwardly toward the first end portion 72A, so that the first end portion 72A is positioned higher than the second end portion 72B. The second tilt position may also be referred to herein as a second position, a second state, a second posture or a first configuration of the belt roller 72. [0038] FIG. 8 illustrates the movement of the endless belt 71 when the belt roller 72 is tilted. As illustrated in FIG. 8, when the belt roller 72 is tilted, the endless belt 71 suspended between the belt roller 72 and the heating roller 73 is twisted and the endless belt 71 moves toward the end portion side disposed at a higher position among the pair of end portions of the belt roller 72. When the belt roller 72 is supported in the second tilt position so as to be inclined upwardly toward the first end portion 72A, the endless belt 71 moves in a direction pointed toward the first end portion 72A (e.g., to the right side in the left and right direction). [0039] Namely, when the belt roller 72 moves toward the second end portion 72B, the belt roller 72 is tilted to cause the endless belt 71 to move toward the second end portion 72B. Conversely, when the belt roller 72 moves toward the first end portion 72A, the belt roller 72 is tilted to cause the endless belt 71 to move toward the first end portion 72A. [0040] With reference to FIGS. 9 and 10, an operation of the example gloss treatment device 70 will be described. FIGS. 9 and 10 are plan views of the example gloss treatment device 70. FIG. 9 illustrates a state in which the endless belt 71 moves to the right side in the left and right direction (the direction pointed toward the first end portion 72A) in accordance with the operation of the gloss treatment device 70. As illustrated in FIG. 9, when the endless belt 71 moves to the right side, the first edge portion 71A which is the right edge portion of the endless belt 71 rides on the first contact surface 91 so that the inner peripheral surface of the endless belt 71 contacts the first contact surface 91. [0041] Here, since the diameter of the first contact surface 91 increases toward the first end portion 72A, the linear velocity (the rotation speed) in the area in the vicinity of the first edge portion 71A in the endless belt 71 exceeds the linear velocity in the area in the vicinity of the second edge portion 71B corresponding to the left edge portion of the endless belt 71 as the endless belt 71 moves to the right side. Consequently, the tension in the area in the vicinity of the first edge portion 71A in the endless belt 71 exceeds the tension in the area in the vicinity of the second edge portion 71B in the endless belt 71 in accordance with a difference in linear velocity. In some examples, the friction coefficients of the first contact surface 91 and the second contact surface 92 may be greater than the friction coefficient of the center contact surface 93, so as to increase the difference in linear velocity and tension between the left and right edge portions of the endless belt 71. [0042] Due to the difference in linear velocity and tension between the pair of left and right edge portions 71A and 71B of the endless belt 71, a force is applied to the endless belt 71 toward the right side (the direction pointed toward the first end portion 72A). At this time, a reaction force is applied to the belt roller 72 in the direction opposite to the endless belt 71, namely, in the left direction (the direction from the first end portion 72A to the second end portion 72B). Since the belt roller 72 is suspended and supported by the support device 100 to be movable in the left and right direction, the belt roller 72 moves to the left side due to the reaction force. [0043] When the belt roller 72 moves to the left side, the tilt position of the belt roller 72 changes to the first tilt position so as to be tilted upwardly toward the second end portion 72B as illustrated in FIG. 6. Namely, the support device 100 supports the belt roller 72 to be tilted in the first tilt position when the endless belt 71 contacts the first contact surface 91 of the belt roller 72 which causes the belt roller 72 to move in the direction pointed toward the second end portion 72B. When the belt roller 72 is tilted in the first tilt position, the endless belt 71 is twisted so that the endless belt 71 moves in the direction pointed toward the second end portion 72B disposed at a relatively high position, namely, toward the left direction. [0044] Conversely, as illustrated in FIG. 10, when the endless belt 71 moves to the left side in the left and right direction (pointed toward the second end portion 72B), the second edge portion 71B of the endless belt 71 rides on the second contact surface 92 so that the inner peripheral surface of the endless belt 71 contacts the second contact surface 92. [0045] Here, since the diameter of the second contact surface 92 increases toward the second end portion 72B, the linear velocity in the area in the vicinity of the second edge portion 71B in the endless belt 71 exceeds the linear velocity in the area in the vicinity of the first edge portion 71A of the endless belt 71 as the endless belt 71 moves to the left side. Consequently, the tension in the area in the vicinity of the second edge portion 71B in the endless belt 71 exceeds the tension in the area in the vicinity of the first edge portion 71A in the endless belt 71 in accordance with a difference in linear velocity. In some examples, the friction coefficients of the first contact surface 91 and the second contact surface 92 may be greater than the friction coefficient of the center contact surface 93, so as to increase the difference in linear velocity and tension between the left and right edge portions of the endless belt 71. [0046] Due to the difference in linear velocity and tension between the pair of left and right edge portions 71A and 71B of the endless belt 71, a force is applied to the endless belt 71 toward the left side (the direction pointed toward the second end portion 72B). At this time, a reaction force is applied to the belt roller 72 in the direction opposite to the endless belt 71, namely, in the right direction (the direction from the second end portion 72B to the first end portion 72A). Since the belt roller 72 is suspended and supported by the support device 100 to be movable in the left and right direction, the belt roller 72 moves to the right side due to the reaction force. [0047] When the belt roller 72 moves to the right side, the tilt position of the belt roller 72 changes to the second tilt position so as to be tilted upwardly toward the first end portion 72A as illustrated in FIG. 7. Namely, the support device 100 supports the belt roller 72 to be tilted in the second tilt position when the endless belt 71 contacts the second contact surface 92 of the belt roller 72 which causes the belt roller 72 to move in the direction pointed toward the first end portion 72A. When the belt roller 72 is tilted in the second tilt position, the endless belt 71 is twisted so that the endless belt 71 moves in the direction pointed toward the first end portion 72A disposed at a relatively high position, namely, toward the right direction. [0048] As described above, when the endless belt 71 moves to the right side, the belt roller 72 is tilted in the first tilt position so that the endless belt 71 is pushed back to the left side. Conversely, when the endless belt 71 moves to the left side, the belt roller 72 is tilted in the second tilt position so that the endless belt 71 is pushed back to the right side. Accordingly, the position of the endless belt 71 can be maintained in the vicinity of the center in the left and right direction, so as to prevent or inhibit the first edge portion 71A and the second edge portion 71B of the endless belt 71 from contacting the frame or the like, and thereby prevent or inhibit damaging the endless belt 71. [0049] Next, the operation and effect of the gloss treatment device 70 and the imaging apparatus 1 will be described based on experimental examples, but the present disclosure is not limited to the following experimental examples. [0050] FIG. 11 illustrates a change over time in the moving distances of the endless belt 71 and the belt roller 72 in the left and right direction when the gloss treatment device 70 illustrated in FIG. 2 is operated. Based FIG. 11, when the endless belt 71 moves to the left side, the belt roller 72 moves to the right side. Then, the endless belt 71 is pushed back to the right side as the belt roller 72 moves to the right side. Similarly, when the endless belt 71 moves to the left side, the belt roller 72 moves to the right side and hence the endless belt 71 is pushed back to the right side. From the result illustrated in FIG. 11, according to the gloss treatment device 70, it was found that the endless belt 71 was maintained in the vicinity of the center position in the left and right direction. [0051] Although various examples have been described and shown herein, it should be understood that the examples described can be modified in their arrangement and details. [0052] For example, although in the above-described example, the diameters of the first contact surface 91 and the second contact surface 92 are respectively formed to increase toward the first end portion 72A and the second end portion 72B of the belt roller 72, respectively, in other examples, the first contact surface 91 and the second contact surface 92 may have friction coefficients that are greater than the friction coefficient of the center contact surface 93, and the diameters of the first contact surface 91 and the second contact surface 92 may be substantially constant in the longitudinal direction. The friction coefficients of the first contact surface 91 and the second contact surface 92 may be greater than the friction coefficient of the center contact surface 93 to cause a difference in linear velocity and tension between the first edge portion 71A and the second edge portion 71B of the endless 71, even though the diameters of the first contact surface 91 and the second contact surface 92 are constant, so as to cause the belt roller 72 to move in the direction opposite to the moving direction of the endless belt 71. Consequently, the endless belt 71 can be pushed back (e.g., corrected in alignment) in the direction opposite to the moving direction of the endless belt 71 by tilting the belt roller 72. [0053] In addition, although in the above-described example, the support device 100 includes the pair of rotation arms 102 and 112, in other examples, the support device 100 can have any suitable configuration by which the belt roller 72 is supported in the first tilt position when the belt roller 72 moves toward the second end portion 72B and is additionally supported to be tilted in the second tilt position when the belt roller 72 moves toward the first end portion 72A. [0054] For example, as illustrated in FIG. 12A, the support device 100 may include two guide members 102A (a first guide member and a second guide member) which are respectively connected to the first end portion 72A and the second end portion 72B of the belt roller 72. The guide member 102A is provided with a groove 107A which is tilted upward toward the outside of the belt roller 72. The groove 107A accommodates a pin 106 which protrudes forward from the support frame 101. This guide member 102A guides the pin 106 so that the second end portion 72B moves upward while the pin is accommodated in the groove 107A when the belt roller 72 moves in the direction from the first end portion 72A to the second end portion 72B in the longitudinal direction. Thus, the belt roller 72 can be supported to tilt in the first tilt position when the belt roller 72 moves in the direction pointed toward the second end portion 72B and to tilt in the second tilt position when the belt roller 72 moves in the direction pointed toward the first end portion 72A. [0055] Additionally, the shape of the groove 107A formed in the guide member 102A may not be a linear shape, but may instead have, an arc shape as illustrated in FIG.12B or a curved shape as illustrated in FIG.12C, for example. [0056] In some examples, the inner peripheral surface of the endless belt 71 may have a distribution of different friction coefficients in the left and right direction. For example, an area adjacent to the edge portions 71A and 71B in the width direction of the endless belt in the inner peripheral surface of the endless belt 71 may have a friction coefficient which is greater than a friction coefficient of an area excluding the area adjacent to the edge portions 71A and 71B in the inner peripheral surface of the endless belt 71. With such a configuration, it is possible to further increase the difference in linear velocity and tension between the pair of left and right edge portions 71A and 71B of the endless belt 71. [0057] Additionally, in the example illustrated in FIGS. 6 and 7, the belt roller 72 is tilted so that the first end portion 72A is disposed at a position higher than the second end portion 72B when the belt roller 72 moves to the right side and the second end portion 72B is disposed at a position higher than the first end portion 72A when the belt roller 72 moves to the left side. However, the belt roller 72 may be tilted so that the first end portion 72A is disposed at a position lower than the second end portion 72B when the belt roller 72 moves to the right side and the second end portion 72B is disposed at a position lower than the first end portion 72A when the belt roller 72 moves to the left side. For example, such a configuration can be achieved by turning the support device 100 illustrated in FIG.3, upside down. [0058] As described above, the belt roller can be tilted so that the endless belt 71 moves to the right side when the belt roller 72 moves to the right side and the belt roller can be tilted so that the endless belt 71 moves to the left side when the belt roller 72 moves to the left side by setting, for example, the rotation direction of the endless belt 71 in the opposite direction even when the support device 100 is turned upside down. [0059] Furthermore, the configurations of various gloss treatment devices or imaging apparatuses described above can be combined with each other within a consistent range. [0060] It is to be understood that not all aspects, advantages and features described herein may necessarily be achieved by, or included in, any one particular example. Indeed, having described and illustrated various examples herein, it should be apparent that other examples may be modified in arrangement and detail is omitted.