Fixing device and image forming apparatus

Abstract

To provide a fixing device and an image forming apparatus capable of suppressing a temperature rise of a circulation part by a heating part as compared with a case where the heating part and the circulation part overlap in a width direction of a recording medium.SOLUTION: The fixing device includes a holding unit that extends in a width direction of a recording medium to be transported and holds the recording medium, a pair of rotating units that are attached to both ends of the holding unit and rotate to transport the recording medium, a heating unit that heats the recording medium in a non-contact manner and is accommodated between the pair of rotating units in the width direction, and a blowing unit that blows air toward the recording medium and is accommodated in a region in which the heating unit is disposed in the width direction.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a fixing device and an image forming apparatus. [Background technology]

[0002] In the image forming apparatus described in Patent Document 1, the gap between the endless wire conveying member and the auxiliary conveying member is narrower at the discharge port than at the transfer material inlet. The conveying pulley is rotated by a rotary drive source to drive the conveying member and auxiliary conveying member to convey the transfer material, and the unfixed toner image is heated and melted by radiant heat, and the transfer material is conveyed to the guide member at the entrance of the calender roller. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-148973 Summary of the Invention [Problem to be solved by the invention]

[0004] In a conventional image forming apparatus, a pair of endless orbiting sections are arranged to sandwich the conveyed recording medium in the width direction of the recording medium, and a holding section extends in the width direction of the recording medium, with both ends attached to the pair of orbiting sections, respectively, to hold the leading edge of the recording medium. The pair of orbiting sections transport the recording medium. Furthermore, a heating section, such as a heater, is arranged opposite the conveyed recording medium to heat the conveyed recording medium in a non-contact manner.

[0005] In such a configuration, the heating section and the circulating section overlap in the width direction of the recording medium, so the circulating section is heated by the heating section, causing the temperature of the circulating section to rise.

[0006] An object of the present invention is to suppress the temperature rise of the circulating portion caused by the heating portion, compared to when the heating portion and the circulating portion overlap in the width direction of the recording medium. [Means for solving the problem]

[0007] The fixing device according to the first aspect of the present invention is characterized by comprising a holding section that extends in the width direction of the recording medium being transported and holds the recording medium, a pair of circling sections attached to both ends of the holding section and that rotate to transport the recording medium, a heating section that heats the recording medium without contact and is located between the pair of circling sections in the width direction, and a blowing section that blows air toward the recording medium and is located in the area in the width direction where the heating section is arranged.

[0008] A fixing device according to a second aspect of the present invention is characterized in that, in the fixing device described in the first aspect, it is provided with a reflective section that is arranged on the opposite side of the circulating section across the heating section when viewed from the width direction, and in which a reflective area that reflects heat rays is contained between a pair of the circulating sections in the width direction.

[0009] A fixing device according to a third aspect of the present invention is characterized in that, in the fixing device described in the second aspect, the reflective portion is U-shaped with the recording medium side open when viewed from the recording medium transport direction, and the reflective portion has sides that sandwich the heating portion from the width direction, and in the width direction, the sides are positioned between a pair of the circulating portions.

[0010] A fixing device according to a fourth aspect of the present invention is characterized in that, in the fixing device according to any one of the first to third aspects, it is provided with a heat-shielding section that faces the circulating section in a cross direction that crosses the width direction when viewed from the conveying direction of the recording medium, and that is entirely positioned outside the area in which the heating section is positioned in the width direction.

[0011] A fixing device according to a fifth aspect of the present invention is characterized in that, in the fixing device according to any one of the first to fourth aspects, it comprises a pair of conveying sections that are arranged downstream of the heating section in the conveying direction of the recording medium, sandwich the recording medium while rotating, convey the recording medium, and heat the recording medium.

[0012] An image forming apparatus according to a sixth aspect of the present invention is characterized by comprising: a forming unit that forms a toner image on a recording medium; and the fixing device according to claim 5 that fixes the toner image on the recording medium. [Effects of the Invention]

[0013] According to the fixing device of the first aspect of the present invention, it is possible to suppress the temperature of the circulating part from increasing due to the heating part, compared to when the heating part and the circulating part overlap in the width direction of the recording medium.

[0014] According to the fixing device of the second aspect of the present invention, it is possible to suppress the temperature of the circumferential portion from increasing due to reflected heat rays, compared to when the reflective area and the circumferential portion overlap in the width direction.

[0015] According to the fixing device of the third aspect of the present invention, the temperature rise of the circumferential portion can be suppressed compared to when the side surface is disposed on the outer side between the pair of circumferential portions in the width direction.

[0016] According to the fixing device of the fourth aspect of the present invention, the temperature of the circulating member can be prevented from rising in the width direction, compared to when the heat shielding portion extends to the region where the heating portion is arranged.

[0017] According to the fixing device of the fifth aspect of the present invention, it is possible to suppress the occurrence of wrinkles on the recording medium, compared to when the heating member and the circling member overlap in the width direction.

[0018] According to the image forming apparatus of the sixth aspect of the present invention, it is possible to suppress a decrease in the quality of the output image, compared to when the heating member and the circumferential member overlap in the width direction. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a front view showing a fixing device according to a first embodiment of the present invention. [Figure 2] 1 is a side view showing a fixing device according to a first embodiment of the present invention. [Figure 3] 2 is a perspective view showing a chain, a holding portion, and the like provided in the fixing device according to the first embodiment of the present invention. FIG. [Figure 4] 2 is a plan view showing a chain, a holding portion, and the like provided in the fixing device according to the first embodiment of the present invention. FIG. [Figure 5] 2 is a perspective view showing a main heating section and the like provided in the fixing device according to the first embodiment of the present invention. FIG. [Figure 6] 2 is a cross-sectional view showing a main heating section and the like provided in the fixing device according to the first embodiment of the present invention. FIG. [Figure 7] 2 is a cross-sectional view showing a cooling unit provided in the image forming apparatus according to the first embodiment of the present invention. FIG. [Figure 8] 1 is a configuration diagram showing a toner image forming unit provided in an image forming apparatus according to a first embodiment of the present invention. [Figure 9] 1 is a configuration diagram showing an image forming apparatus according to a first embodiment of the present invention. [Figure 10] FIG. 10 is a front view showing a fixing device according to a comparative example of the present invention. [Figure 11] FIG. 6 is a front view showing a fixing device according to a second embodiment of the present invention. [Figure 12] FIG. 6 is a side view showing a fixing device according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0020] First Embodiment An example of a fixing device and an image forming apparatus according to a first embodiment of the present invention will be described with reference to Figures 1 to 10. In the drawings, arrow H indicates the up-down direction (vertical direction) of the apparatus, arrow W indicates the width direction (horizontal direction) of the apparatus, and arrow D indicates the depth direction (horizontal direction) of the apparatus.

[0021] (Image forming apparatus 10) The image forming apparatus 10 according to the first embodiment is an electrophotographic image forming apparatus that forms a toner image on a sheet member P as a recording medium. As shown in FIG. 9 , the image forming apparatus 10 includes a storage section 50, a discharge section 52, an image forming section 12, a conveying mechanism 60, a reversing mechanism 80, a fixing device 100, and a cooling section 90.

[0022] [Storage section 50] The storage section 50 has a function of storing sheet materials P as recording media. The image forming apparatus 10 is provided with a plurality of (for example, two) storage sections 50. The sheet materials P are selectively sent out from the plurality of storage sections 50.

[0023] [Discharge section 52] The discharge section 52 is a section where the sheet material P on which an image has been formed is discharged. Specifically, after the image has been fixed by the fixing device 100, the sheet material P that has been cooled by the cooling section 90 is discharged to the discharge section 52.

[0024] [Image forming unit 12] The image forming unit 12 has a function of forming an image on the sheet material P by an electrophotographic method. Specifically, the image forming unit 12 includes a toner image forming unit 20 that forms a toner image, and a transfer device 30 that transfers the toner image formed in the toner image forming unit 20 onto the sheet material P. The image forming unit is an example of a forming unit.

[0025] A plurality of toner image forming units 20 are provided to form toner images for each color. The image forming apparatus 10 is provided with toner image forming units 20 for a total of four colors: yellow (Y), magenta (M), cyan (C), and black (K). (Y), (M), (C), and (K) shown in FIG. 9 indicate components corresponding to the above colors.

[0026] -Toner image forming unit 20- The toner image forming units 20 for each color are basically configured in the same way except for the toner used. Specifically, as shown in Fig. 8, the toner image forming units 20 for each color include a photosensitive drum 21 (=photosensitive body) that rotates in the direction of arrow A in the figure, and a charger 22 that charges the photosensitive drum 21. Furthermore, the toner image forming units 20 for each color include an exposure device 23 that exposes the photosensitive drum 21 charged by the charger 22 to light to form an electrostatic latent image on the photosensitive drum 21, and a development device 24 that develops the electrostatic latent image formed on the photosensitive drum 21 by the exposure device 23 with toner to form a toner image.

[0027] -Transfer device 30- The transfer device 30 has a function of primarily transferring the toner images of the photosensitive drums 21 of each color onto an intermediate transfer body in a superimposed manner, and then secondarily transferring the superimposed toner images onto a sheet member P. Specifically, as shown in FIG. 9 , the transfer device 30 includes a transfer belt 31 as an intermediate transfer body, a primary transfer roll 33, and a transfer section 35.

[0028] The primary transfer roll 33 has the function of transferring the toner image formed on the photosensitive drum 21 onto the transfer belt 31 at the primary transfer position T (see Figure 8) between the photosensitive drum 21 and the primary transfer roll 33.

[0029] The transfer belt 31 is endless and its position is determined by being wound around a plurality of rolls 32. When at least one of the rolls 32 is driven to rotate, the transfer belt 31 rotates in the direction of arrow B, and transports the primarily transferred image to the secondary transfer position NT.

[0030] The transfer unit 35 has a function of transferring the toner image transferred onto the transfer belt 31 onto the sheet member P. Specifically, the transfer unit 35 includes a secondary transfer unit 34 and an opposing roll 36.

[0031] The opposing roll 36 is disposed below the transfer belt 31 so as to face the transfer belt 31. The secondary transfer unit 34 is disposed inside the transfer belt 31 so that the transfer belt 31 is disposed between the opposing roll 36 and the secondary transfer unit 34. Specifically, the secondary transfer unit 34 is constituted by a corotron. In the transfer unit 35, the toner image transferred onto the transfer belt 31 is transferred onto the sheet member P passing through the secondary transfer position NT by electrostatic force generated by discharge in the secondary transfer unit 34.

[0032] [Transport mechanism 60] The conveying mechanism 60 has a function of conveying the sheet material P stored in the storage unit 50 to the secondary transfer position NT. Furthermore, the conveying mechanism 60 has a function of conveying the sheet material P from the secondary transfer position NT to the main heating unit 120 described below.

[0033] Specifically, the transport mechanism 60 includes a delivery roll 62 , a plurality of transport rolls 64 , and a chain gripper 66 .

[0034] The delivery roll 62 is a roll that delivers the sheet material P stored in the storage section 50. The plurality of transport rolls 64 are rolls that transport the sheet material P delivered by the delivery roll 62 to the chain gripper 66, or rolls that transport the sheet material P transported by the chain gripper 66 to the cooling section 90.

[0035] The chain gripper 66 has a function of holding the leading end of the sheet material P and transporting the sheet material P. Specifically, as shown in FIG. 3, the chain gripper 66 is made up of a pair of It has a chain 72 and a holding portion 68 that holds the leading end of the sheet material P. A part of the conveying path along which the sheet material P is conveyed in the conveying mechanism 60 is indicated by a dashed line.

[0036] In this embodiment, the chain 72 and the holding portion 68 that constitute the chain gripper 66 are also components of the fixing device 100. The chain 72 and the holding portion 68 will be described in detail later.

[0037] [Reversing mechanism 80] The reversing mechanism 80 is a mechanism that reverses the sheet member P. Specifically, as shown in FIG. 9, the reversing mechanism 80 includes a plurality of transport rolls 82, a reversing device 84, and a plurality of transport rolls 86.

[0038] The plurality of transport rolls 82 are rolls that transport the sheet material P sent from the fixing device 100 to the reversing device 84. The reversing device 84 is, for example, a device that transports the sheet material P while folding it over multiple times so that the transport direction of the sheet material P changes, for example, by 90 degrees at a time, thereby twisting the sheet material P like a Möbius strip and reversing the sheet material P upside down.

[0039] The plurality of transport rolls 86 are rolls that transport the sheet member P, which has been turned over by the turnover device 84, to the chain gripper 66.

[0040] [Fixing device 100] The fixing device 100 has a function of fixing the toner image transferred onto the sheet member P by the transfer device 30 onto the sheet member P. The fixing device 100 will be described in detail later.

[0041] [Cooling section 90] The cooling section 90 has a function of cooling the sheet member P heated by the fixing device 100. As shown in FIG. 9, the cooling section 90 is disposed downstream of the fixing device 100 in the conveying direction of the sheet member P. The cooling section 90 also includes two cooling rolls 92 arranged side by side in the device width direction. The two cooling rolls 92 have the same configuration, so only one of the cooling rolls 92 will be described.

[0042] As shown in FIG. 7, the cooling roll 92 includes a roll 92a arranged on the upper side across the conveying path of the sheet material P, and a roll 92b arranged on the lower side across the conveying path of the sheet material P.

[0043] Rollers 92a, 92b are cylindrical and extend in the depth direction of the device, and have cylindrical base members 94a, 94b. Base members 94a, 94b are aluminum tubes, and an air flow generated by a blower mechanism (not shown) is generated inside base members 94a, 94b. This air flow reduces the surface temperature of rolls 92a, 92b compared to the temperature when no air flow occurs.

[0044] In this configuration, the roll 92b rotates by receiving a rotational force from a driving member (not shown). Furthermore, the roll 92a rotates in response to the rotation of the roll 92b. The rolls 92a and 92b sandwich and transport the sheet material P, thereby cooling the sheet material P.

[0045] (Action of image forming device) In the image forming apparatus 10 shown in FIG. 9, an image is formed as follows.

[0046] First, the charger 22 (see FIG. 8) for each color to which a voltage is applied uniformly negatively charges the surface of the photosensitive drum 21 for each color at a predetermined potential. Next, based on image data input from the outside, the exposure device 23 irradiates the charged surface of the photosensitive drum 21 for each color with exposure light to form an electrostatic latent image.

[0047] As a result, electrostatic latent images corresponding to the image data are formed on the surfaces of the respective photosensitive drums 21. The developing devices 24 for each color then develop these electrostatic latent images into visible toner images. The transfer devices 30 then transfer the toner images formed on the surfaces of the photosensitive drums 21 for each color onto the transfer belt 31.

[0048] 9 to the conveying path of the sheet material P by the delivery roll 62, and the sheet material P conveyed by the chain gripper 66 is sent to the secondary transfer position NT where the transfer belt 31 and the opposing roll 36 come into contact with each other. At the secondary transfer position NT, the sheet material P is conveyed while being sandwiched between the transfer belt 31 and the opposing roll 36, so that the toner image on the surface of the transfer belt 31 is transferred to the surface of the sheet material P.

[0049] Furthermore, the fixing device 100 fixes the toner image transferred onto the surface of the sheet material P to the sheet material P, and the sheet material P is transported to the cooling section 90. The cooling section 90 cools the sheet material P on which the toner image has been fixed, and discharges it to the discharge section 52.

[0050] On the other hand, when a toner image is formed on the rear surface of the sheet material P, the sheet material P, which has been conveyed by the chain gripper 66 and passed through the fixing device 100, is conveyed to the conveying rolls 82 of the reversing mechanism 80, and the sheet material P conveyed by the conveying rolls 82 is reversed by the reversing device 84. The conveying rolls 86 then convey the reversed sheet material P to the chain gripper 66. The chain gripper 66 conveys the sheet material P. Then, in order to form a toner image on the rear surface of the sheet material P, the above-described process is performed again.

[0051] (Main part configuration) Next, the fixing device 100 will be described.

[0052] As shown in FIG. 2, the fixing device 100 includes a chain gripper 66 and a preheating section 102 that is arranged downstream of the transfer device 30 (see FIG. 9) in the conveying direction of the sheet material P and heats the conveyed sheet material P in a non-contact manner.

[0053] Furthermore, the fixing device 100 includes a main heating section 120 that contacts the sheet material P to heat and pressurize it, a spray unit 170, and a heat shielding member 108 (see FIG. 1) that blocks heat emitted from the preheating section 102 and transmitted to the chain 72 of the chain gripper 66.

[0054] [Chain Gripper 66] The chain gripper 66 includes a pair of chains 72 and a holding portion 68 that holds the sheet material P. The chains 72 are an example of a circulating portion.

[0055] -Chain 72- 3, the pair of chains 72 are spaced apart in the device depth direction. Furthermore, the chain 72 is formed endlessly and includes a plurality of metal outer plates 72a, a plurality of metal inner plates 72b, and pins 72c that connect the outer plates 72a and the inner plates 72b. In this embodiment, the device depth direction is the same direction as the width direction of the sheet material P being conveyed.

[0056] The pair of chains 72 are arranged on one end side and the other end side in the axial direction relative to the opposing roll 36 (see FIG. 9), and are wound around a pair of sprockets (not shown) whose axial direction is the depth direction of the device, a pair of sprockets 71 (see FIG. 5) arranged on one end side and the other end side in the axial direction relative to the pressure roll 140 described below, and a pair of sprockets 74 (see FIG. 9) arranged at a distance in the depth direction of the device. When either of these pair of sprockets rotates, the chain 72 moves in the direction of arrow C. In addition, both ends of a holding portion 68 that holds a sheet material P are attached to the pair of chains 72.

[0057] -Holding part 68- As shown in Figure 3, the holding portion 68 has both ends attached to a pair of chains 72, and is equipped with an attachment member 75 extending in the depth direction of the device, and a gripper 76 attached to the attachment member 75.

[0058] A plurality of holding portions 68 are provided and are arranged at predetermined intervals along the circumferential direction (circumferential direction) of the chain 72.

[0059] A plurality of grippers 76 are provided and attached to the attachment member 75 at predetermined intervals along the depth direction of the device. The grippers 76 have the function of holding the leading edge of the sheet material P. Specifically, the grippers 76 have claws 76a. The attachment member 75 is also formed with contact portions 75a (see FIG. 6) with which the claws 76a come into contact.

[0060] The gripper 76 is configured to hold the sheet material P by pinching the leading end of the sheet material P between the claw 76a and the contact portion 75a. Note that the gripper 76 has the claw 76a pressed against the contact portion 75a by a spring or the like, and the claw 76a is moved toward and away from the contact portion 75a by the action of a cam or the like, for example.

[0061] In this configuration, in the chain gripper 66, the gripper 76 holds the leading edge of the sheet material P, and the chain 72 rotates in the direction of arrow C to transport the sheet material P. The chain gripper 66 shown in FIG. 9 transports the sheet material P transported by the multiple transport rolls 64 to the secondary transfer position NT, and then transports the sheet material P to the main heating unit 120 after passing through the preheating unit 102.

[0062] [Main heating section 120] 2, the main heating section 120 is disposed downstream of the preheating section 102 in the conveying direction of the sheet member P. The main heating section 120 includes a heating roll 130 that comes into contact with the conveyed sheet member P to heat the sheet member P, a pressure roll 140 that presses the sheet member P toward the heating roll 130, and a driven roll 150 that rotates in response to the rotation of the rotating heating roll 130.

[0063] -Heated Roll 130- 2, the heating roll 130 is disposed so as to contact the upward surface of the sheet member P being conveyed and extend in the depth direction of the device with its axial direction being the depth direction of the device. The heating roll 130 also has a cylindrical base material 132, a rubber layer 134 formed to cover the entire periphery of the base material 132, a release layer 136 formed to cover the entire periphery of the rubber layer 134, and a heater 138 housed inside the base material 132. The outer diameter of the outer peripheral surface of the release layer 136 of the heating roll 130 is, for example, 80 mm.

[0064] The base material 132 is an aluminum pipe, and for example, has a thickness of 20 mm. The rubber layer 134 is made of silicone rubber, and for example, has a thickness of 6 mm. The release layer 136 is made of a mixture of tetrafluoroethylene and perfluoroethylene. It is made of a styrene copolymer (PFA resin) and has a thickness of 50 μm, for example.

[0065] 5, shafts 139a extending in the device depth direction are formed on both ends of the heating roll 130 in the device depth direction, and support members 139b are provided to support the shafts 139a, respectively. As a result, the heating roll 130 is rotatably supported by the support members 139b at both ends of the heating roll 130.

[0066] -Following roll 150- 2 and 5, the driven roll 150 is disposed on the opposite side of the sheet member P conveyed across the heating roll 130, so as to extend in the device depth direction with its axial direction being the device depth direction. The driven roll 150 also has a cylindrical base material 152 and a heater 154 housed inside the base material 152. The outer diameter of the outer peripheral surface of the base material 152 of the driven roll 150 is, for example, 50 mm.

[0067] The substrate 152 is an aluminum tube having a thickness of, for example, 10 mm. The driven roll 150 is rotatably supported at both ends thereof by support members (not shown).

[0068] In this configuration, the driven roll 150 rotates following the rotation of the heating roll 130. The driven roll 150 heats the heating roll 130. In this way, the heating roll 130 is heated by the driven roll 150, and the heating roll 130 itself has the heater 138, so that the surface temperature of the heating roll 130 becomes a predetermined value of 180°C or more and 200°C or less.

[0069] -Pressure Roll 140- As shown in FIGS. 2 and 5, the pressure roll 140 is disposed on the opposite side of the heating roll 130 with the conveyed sheet material P sandwiched therebetween, in contact with the downward-facing surface of the conveyed sheet material P, and extends in the device depth direction with its axial direction being the device depth direction. The pressure roll 140 also has a cylindrical substrate 142, a rubber layer 144 formed to cover the substrate 142, a release layer 146 formed to cover the rubber layer 144, and a pair of shaft portions 148 (see FIG. 5) formed at both ends in the device depth direction. The outer diameter of the outer peripheral surface of the release layer 146 of the pressure roll 140 is, for example, 225 mm. In this way, the outer diameter of the pressure roll 140 is larger than the outer diameter of the heating roll.

[0070] The substrate 142 is an aluminum tube having a thickness of, for example, 20 mm. The rubber layer 144 is made of silicone rubber having a thickness of, for example, 1 mm. The release layer 146 is made of a copolymer of tetrafluoroethylene and perfluoroethylene (PFA resin) having a thickness of, for example, 50 μm.

[0071] 6, a recess 140a extending in the device depth direction is formed on the outer peripheral surface of the pressure roll 140. When the sheet material P passes between the pressure roll 140 and the heating roll 130, the gripper 76 that grips the leading end of the sheet material P is accommodated in this recess 140a.

[0072] As shown in FIG. 5, the pair of shaft portions 148 are formed at both ends in the depth direction of the device, have a smaller diameter than the outer peripheral surface of the release layer 146 of the pressure roll 140, and extend in the axial direction.

[0073] In this configuration, the pressure roll 140 rotates by a rotational force transmitted from a driving member (not shown). The heating roll 130 rotates following the rotation of the rotating pressure roll 140, and the driven roll 150 rotates following the rotation of the rotating heating roll 130. Furthermore, the heating roll 130 and the pressure roll 140 sandwich and transport the sheet member P onto which the toner image has been transferred, thereby fixing the toner image to the sheet member P. In this way, the heating roll 130 and the pressure roll 140 sandwich and transport the sheet member P while rotating, thereby forming a pair of transport units 122 that heat the sheet member P.

[0074] -others- 5, the main heating section 120 includes a support member 156 that supports the pressure roll 140, and a biasing member 158 that biases the pressure roll 140 toward the heating roll 130 via the support member 156. A pair of support members 156 are provided. The pair of support members 156 are arranged so as to rotatably support the pair of shafts 148 of the pressure roll 140 from below.

[0075] The biasing members 158 are compression springs, and are provided in pairs and are arranged on opposite sides of the shaft portion 148 with the support member 156 interposed therebetween.

[0076] In this configuration, the pair of biasing members 158 bias the pressure roll 140 toward the heating roll 130, causing the pressure roll 140 to press the sheet member P toward the heating roll 130. Then, as shown in Fig. 2, the portion of the heating roll 130 biased by the pressure roll 140 is deformed, and a nip portion N is formed, which is a region where the heating roll 130 and the pressure roll 140 come into contact with each other.

[0077] [Preheating section 102] As shown in FIG. 2, the preheating unit 102 is disposed downstream of a secondary transfer position NT (see FIG. 9) where a toner image is transferred onto the sheet member P, and upstream of the main heating unit 120, in the conveying direction of the sheet member P. Furthermore, the preheating unit 102 is disposed above the conveyed sheet member P (=the side where the toner image is transferred). The preheating unit 102 includes a reflecting member 104, a plurality of infrared heaters 106 (hereinafter referred to as "heaters 106"), a heating plate 114, and a wire mesh 112.

[0078] -Reflective member 104- The reflecting member 104 is formed using an aluminum plate and has a shallow box shape with an open side facing the sheet material P to be conveyed. In other words, when viewed from the width direction of the device, it has a U-shape with an open side facing the sheet material P to be conveyed. In this embodiment, when viewed from above, the reflecting member 104 covers the sheet material P to be conveyed in the depth direction and width direction of the device. The reflecting member 104 is an example of a reflecting section.

[0079] As shown in Fig. 1, the reflecting member 104 has a heating plate 114 and a heater 106 arranged in this order from the side of the sheet material P being conveyed. The reflecting member 104 also has a reflecting surface 104a formed thereon, which reflects infrared rays, which are heat rays emitted by the heater 106, toward the heating plate 114. In other words, as shown in Fig. 2, the reflecting surface 104a, which reflects infrared rays toward the heating plate 114, is arranged on the opposite side of the chain 72, with the heater 106 and the heating plate 114 sandwiched between them. In this way, the reflecting surface 104a functions as an emission direction changing means for changing the emission direction of infrared rays emitted from the heater 106 in a direction different from the heating plate 114 side, toward the heating plate 114.

[0080] Furthermore, as shown in FIG. 1, the reflection area (H01 in the drawing) where the infrared rays are reflected by the reflection surface 104a toward the heating plate 114 is located between the pair of chains 72 in the depth direction of the device. In other words, the chain 72 and the reflective area H01 do not overlap in the device depth direction.

[0081] Here, "the area S01 between a pair of chains 72 in the depth direction of the device" refers to the area sandwiched between the part of one chain 72 that is closest to the other chain 72 and the part of the other chain 72 that is closest to the one chain 72 in the depth direction of the device.

[0082] The reflecting member 104 also has a pair of side plates 105 that sandwich the heater 106 and the heating plate 114 from the depth direction of the device. As described above, the heating plate 114 and the heater 106 are disposed inside the reflecting member 104. That is, the lower ends of the side plates 105 are positioned below the heating plate 114 in the vertical direction of the device. In other words, the lower ends of the side plates 105 protrude downward from the heating plate 114 in the vertical direction of the device.

[0083] Furthermore, the pair of side plates 105 are each formed with opposing surfaces 105a that face each other, and in the device depth direction, the pair of opposing surfaces 105a are disposed between the pair of chains 72 at a distance S01. The opposing surfaces 105a are an example of side surfaces.

[0084] -Heater 106- The heater 106 is an infrared heater having a cylindrical outer shape, and as shown in Fig. 1, it faces the reflecting surface 104a of the reflecting member 104 in the vertical direction of the device and extends in the depth direction of the device. Furthermore, a plurality of heaters 106 are provided and are arranged in the width direction of the device as shown in Fig. 2. The heater 106 is an example of an emission section that emits heat rays.

[0085] In the above configuration, when a voltage is applied from a power supply (not shown), the heater 106 emits infrared rays with a maximum spectral radiance at a wavelength of 3 μm or more and 5 μm or less.

[0086] -Heating plate 114- The heating plate 114 is formed, for example, using a stainless steel plate with a thickness of 1 mm, and is disposed between the chains 72 and the heater 106 as seen from the depth direction of the device, as shown in Fig. 2. In other words, the heater 106 is disposed on the opposite side of the chains 72 with the heating plate 114 in between as seen from the depth direction of the device. The heating plate 114 is also disposed, for example, 30 mm away from the leading edge of the sheet material P being conveyed in the vertical direction of the device. The heating plate 114 is an example of a heating unit.

[0087] Furthermore, a plurality of heating plates 114 are arranged in the width direction of the device, with their plate surfaces facing the sheet material P being transported. The outer shape of the plurality of arranged heating plates 114 is a rectangle extending in the width direction of the device when viewed from the top-bottom direction of the device. In this embodiment, the plurality of heating plates 114 arranged without gaps when viewed from above are configured to cover the sheet material P being transported. In other words, there are times when the entire sheet material P being transported is heated at once by the plurality of arranged heating plates 114.

[0088] 1, in the device depth direction, the heating plate 114 is contained in the space S01 between the pair of chains 72. In other words, in the device depth direction, the area (H02 in the figure) where the heating plate 114 is arranged is contained in the space S01 between the pair of chains 72. In other words, in the device depth direction, the chains 72 and the area H02 where the heating plate 114 is arranged do not overlap.

[0089] Furthermore, in the depth direction of the device, the heating plate 114 is contained in the area (H03 in the drawing) where the heater 106 is disposed. The region H02 where the heater 106 is located is contained within the region (H03 in the drawing) where the heater 106 is located. A black coating is formed on the plate surface of the heating plate 114 on the heater 106 side. In the depth direction of the device, the region H02 and the region H03 are contained within the reflective region H01.

[0090] In this configuration, the heating plate 114 absorbs the infrared rays emitted by the heater 106 and the infrared rays reflected by the reflective surface 104a, and the temperature of the heating plate 114 rises and dissipates heat. Then, the temperature of the heating plate 114 rises to, for example, 600°C or more and 1175°C or less, and the heating plate 114 heats the conveyed sheet material P in a non-contact manner.

[0091] In the width direction of the device, the heating plate 114 is disposed in the same area as the area in which the heater 106 is disposed.

[0092] -Wire Mesh 112- The wire mesh 112 is fixed to the edge of the reflecting member 104 by a fixing member (not shown), and as shown in Fig. 1, separates the inside of the reflecting member 104 from the outside of the reflecting member 104. In this way, the wire mesh 112 prevents the sheet material P being conveyed from coming into contact with the heating plate 114.

[0093] [Spraying Unit 170] 2, the blowing unit 170 is disposed opposite the preheating section 102 in the vertical direction of the device, and the conveyed sheet material P passes between the blowing unit 170 and the preheating section 102. In addition, the blowing unit 170 includes a plurality of fans 172 arranged in the width direction and the depth direction of the device, as shown in FIG.

[0094] In this configuration, the fans 172 blow air toward the sheet material P being transported, thereby stabilizing the transport posture of the sheet material P. In this way, the fans 172 function as posture stabilizing means for stabilizing the transport posture of the sheet material P being transported.

[0095] [Heat shielding member 108] A pair of heat shields 108 are provided, and are formed, for example, using stainless steel plates with a thickness of 1 mm, and as shown in Figure 1, they face the chains 72 in the vertical direction of the device when viewed in the width direction of the device. The heat shields 108 are an example of a heat shield.

[0096] Specifically, as shown in Fig. 2, in the width direction of the device, the heat shield 108 is disposed in at least the region where the preheating unit 102 is disposed. Furthermore, as shown in Fig. 1, the heat shield 108 is L-shaped when viewed in the width direction of the device, and has an opposing plate 108a that faces the chain 72 in the vertical direction of the device, and a side plate 108b that covers the chain 72 from the outside in the depth direction of the device. The vertical direction of the device is an example of a cross direction.

[0097] The upward-facing surface of the opposing plate 108a is not painted, and has an average surface roughness Ra (JIS B 0031) of 1 μm or less. Furthermore, in the depth direction of the device, the heat shield 108 is disposed outside the region H02 in which the heating plate 114 is disposed. In other words, in the depth direction of the device, the heat shield 108 and the region H02 in which the heating plate 114 is disposed do not overlap.

[0098] In this configuration, the heat shield 108 blocks heat emitted from the heating plate 114 of the preheating section 102 and transferred to the chain 72 .

[0099] (Function of main components) Next, the operation of the fixing device 100 will be described in comparison with a fixing device 600 according to a comparative embodiment. First, the configuration of the fixing device 600 according to the comparative embodiment will be described, focusing on the differences from the fixing device 100.

[0100] [Fixing device 600] 10, the fixing device 600 includes a preheating section 602 that heats the sheet material P being conveyed without contacting the sheet material P, a chain 72, and a holding section 68. The fixing device 600 also includes a main heating section 120 (see FIG. 2) that contacts the sheet material P to heat and pressurize the sheet material P, and a blowing unit 170. Note that the fixing device 600 does not include a heat shielding member that blocks heat emitted from the heating plate 614 and transmitted to the chain 72.

[0101] -Preheating section 602- As shown in FIG. 10, the preheating unit 602 includes a reflecting member 604, a plurality of infrared heaters 606 (hereinafter referred to as “heaters 606”), a heating plate 614, and a wire mesh 612.

[0102] The reflecting member 604 is made of an aluminum plate and has a shallow box shape with an open side facing the conveyed sheet material P. The reflecting member 604 is formed with a reflecting surface 604a that reflects infrared rays, which are heat rays emitted by the heater 606, toward the heating plate 614.

[0103] In the device depth direction, the reflection area (H11 in the drawing) where infrared rays are reflected by the reflection surface 604a toward the heating plate 614 does not fit within the gap S01 between the pair of chains 72, but protrudes from the gap S01 between the pair of chains 72.

[0104] The reflecting member 604 also has a pair of side plates 605 that sandwich the heater 606 and the heating plate 614 from the depth direction of the device. The lower ends of the side plates 605 are positioned below the heating plate 614 in the vertical direction of the device.

[0105] Further, the pair of side plates 605 are formed with opposing surfaces 605a that face each other, and the pair of opposing surfaces 605a are not disposed between the pair of chains 72 in the depth direction of the device.

[0106] 10, the heater 606 is an infrared heater having a cylindrical outer shape, and faces the reflecting surface 604a of the reflecting member 604 in the vertical direction of the device, and extends in the depth direction of the device. Furthermore, a plurality of heaters 606 are provided, and are arranged in the width direction of the device.

[0107] The heating plates 614 are arranged in a plurality in the width direction of the device, with their plate surfaces facing the sheet material P being conveyed. The outer shape of the arranged heating plates 614 is a rectangle extending in the width direction of the device when viewed from the top-bottom direction. Furthermore, in the depth direction of the device, the area (H12 in the figure) where the heating plates 614 are arranged does not fit within the space S01 between the pair of chains 72, but protrudes from the space S01 between the chains 72. In other words, the heating plates 614 and the chains 72 overlap in the depth direction of the device. Furthermore, in other words, when viewed from the width direction of the device, the chains 72 and the heating plates 614 face each other in the top-bottom direction of the device.

[0108] Further, in the depth direction of the device, the region H12 in which the heating plate 614 is arranged is contained within the region (H13 in the drawing) in which the heater 606 is arranged.

[0109] Furthermore, the wire mesh 612 is fixed to the edge of the reflecting member 604 with a fixing member (not shown). As shown in FIG. 10, the inside of the reflecting member 604 is separated from the outside of the reflecting member 604 .

[0110] [Function of Fixing Devices 100 and 600] When the fixing device 100, 600 is not in operation, no voltage is applied to the heater 106, 606, the chain 72 is stopped, and the fan 172 of the blowing unit 170 is stopped.

[0111] When the image forming operation starts, the chain 72 starts to operate, and the rotating chain 72 transports the sheet material P onto which the toner image has been transferred. Furthermore, the fan 172 starts to operate, and the fan 172 blows air onto the sheet material P from below, so that the sheet surface of the sheet material P faces in the vertical direction.

[0112] 1 and 10, a voltage is applied to the heaters 106 and 606 of the preheating units 102 and 602. The heating plates 114 and 614 absorb infrared rays emitted by the heaters 106 and 606 to which voltage is applied and infrared rays reflected by the reflecting surfaces 104a and 604a, thereby increasing in temperature and dissipating heat. The heated heating plates 114 and 614 then heat the sheet material P conveyed by the rotating chains 72 from above without contact. As the sheet material P is heated, the toner constituting the toner image transferred to the sheet material P softens.

[0113] 2, the heating roll 130 and the pressure roll 140 sandwich and transport the sheet member P heated by the heating plates 114, 614 of the preheating units 102, 602, and fix the toner image onto the sheet member P. The sheet member P with the fixed toner image passes through the cooling unit 90 (see FIG. 9) and is discharged to the outside of the device.

[0114] In the preheating section 602 of the fixing device 600 according to the comparative example, as shown in FIG. 10 , the region H12 where the heating plate 614 is located is not contained within the gap S01 between the pair of chains 72 in the device depth direction, but protrudes from the gap S01 between the pair of chains 72. Therefore, the heat emitted by the heating plate 614 increases the temperature of the pair of chains 72. The pair of chains 72 then extend in the circumferential direction. If the extension amount of one chain 72 differs from the extension amount of the other chain 72, the sheet material P being conveyed will tilt with respect to the conveyance direction and be sandwiched between the heating roll 130 and the pressure roll 140 in this state. This may cause wrinkles to form in the sheet material P.

[0115] 1, in the preheating section 102 of the fixing device 100 according to the embodiment, the region H02 where the heating plate 114 is arranged is located within the space S01 between the pair of chains 72 in the device depth direction. Therefore, compared to when the fixing device 600 is used, the temperature rise of the chains 72 due to the heating plate 114 is suppressed. By suppressing the temperature rise of the chains 72, compared to when the fixing device 600 is used, the sheet material P being conveyed is prevented from tilting with respect to the conveying direction, and the sheet material P is sandwiched between the heating roll 130 and the pressure roll 140, which suppresses the occurrence of paper wrinkles.

[0116] (summary) As described above, in the fixing device 100, the region H02 in which the heating plate 114 is arranged in the device depth direction is contained within the space S01 between the pair of chains 72. Therefore, compared to when the fixing device 600 is used, the temperature of the chains 72 is prevented from rising due to the heating plate 114.

[0117] In the fixing device 100, the heating plate 114, the plate surface of which faces the conveyed sheet material P, The heater 106 absorbs the infrared rays emitted by the heater 106, dissipating heat and heating the sheet material P. Therefore, compared to when the heating plate surface is wavy, for example, the distance between the heating plate 114 and the sheet material P is prevented from varying partially, and temperature unevenness of the heated sheet material P is reduced.

[0118] Furthermore, in the fixing device 100, the region H02 where the heating plate 114 is disposed is contained within the region H03 where the heater 106 is disposed in the device depth direction. Therefore, temperature unevenness occurring in the heating plate 114 is suppressed compared to when the region where the heating plate is disposed protrudes from the region where the heater is disposed in the device depth direction.

[0119] Furthermore, in the fixing device 100, temperature unevenness occurring in the heating plate 114 is suppressed, and the entire heating plate 114 uniformly absorbs infrared rays, so that the temperature of the entire heating plate 114 rises uniformly in the depth direction of the device compared to when the area where the heating plate is located protrudes from the area where the heater is located.

[0120] Furthermore, in the fixing device 100, in the device depth direction, a reflection area H01 where infrared rays are reflected by the reflection surface 104a toward the heating plate 114 is contained within the space S01 between the pair of chains 72. Therefore, compared to the fixing device 600, in which the reflection area H11 of the reflection surface 604a is not contained within the space S01 between the chains 72 and protrudes from the space S01 between the chains 72, an increase in the temperature of the chains 72 due to infrared rays reflected from the reflection surface 104a is suppressed.

[0121] Furthermore, in the fixing device 100, the pair of opposing surfaces 105a formed on the reflecting member 104 are contained within the space S01 between the pair of chains 72. Therefore, compared to the fixing device 600 in which the pair of opposing surfaces 605a are not contained within the space S01 between the chains 72, the heat inside the reflecting member 104 is prevented from being released toward the chains 72, thereby preventing the temperature of the chains 72 from rising.

[0122] Furthermore, in the fixing device 100, the lower ends of the side plates 105 are positioned below the heating plate 114 in the vertical direction of the device. Therefore, compared to when the lower ends of the side plates are positioned above the heating plate, the heat inside the reflecting member 104 is prevented from being released toward the chain 72, thereby preventing the temperature of the chain 72 from rising.

[0123] Furthermore, in the fixing device 100, the heat shield 108 having the opposing plate 108a that faces the chain 72 in the vertical direction of the device is disposed outside the region H02 in which the heating plate 114 is disposed in the depth direction of the device. Therefore, compared to when the heat shield extends to the region in which the heating plate is disposed in the depth direction of the device, the temperature rise of the heat shield 108 is suppressed, and therefore the temperature rise of the chain 72 is suppressed.

[0124] In the fixing device 100, the upward-facing surface of the opposing plate 108a of the heat-shielding member 108 is not painted and has an average surface roughness Ra (JIS B 0031) of 1 μm or less. Therefore, compared to when the average surface roughness Ra of the upward-facing surface of the opposing plate 108a exceeds 1 μm, the heat emitted by the heating plate 114 is more effectively reflected, thereby suppressing an increase in the temperature of the chains 72.

[0125] Furthermore, in the fixing device 100, compared to when the fixing device 600 is used, the sheet material P being transported is prevented from tilting relative to the transport direction, thereby preventing the paper from being pinched between the heating roll 130 and the pressure roll 140 and causing wrinkles.

[0126] Furthermore, in the image forming apparatus 10, the occurrence of paper wrinkles is suppressed compared to when the fixing device 600 is provided. By limiting the amount of image distortion, deterioration in the quality of the output image is suppressed.

[0127] Second Embodiment An example of a fixing device and an image forming apparatus according to a second embodiment of the present invention will be described with reference to Figures 11 and 12. Note that, with regard to the second embodiment, differences from the first embodiment will be mainly described.

[0128] 12, the fixing device 300 of the image forming apparatus 210 according to the second embodiment includes a preheating section 302 that heats the sheet material P being conveyed without contacting the sheet material P, a chain 72, and a holding section 68. The fixing device 300 further includes a main heating section 120 that contacts the sheet material P to heat and pressurize the sheet material P, a blowing unit 170, and a heat shielding member 108 that blocks heat emitted from the preheating section 302 and transmitted to the chain 72.

[0129] (Preheating section 302) As shown in FIG. 11, the preheating unit 302 includes a reflecting member 304, a plurality of infrared heaters 306 (hereinafter referred to as “heaters 306”), and a wire mesh 312.

[0130] The reflecting member 304 is made of an aluminum plate and has a shallow box shape with an open side facing the conveyed sheet material P. The reflecting member 304 is formed with a reflecting surface 304a that reflects infrared rays emitted from a filament 306b of the heater 306, which will be described later.

[0131] In the device depth direction, a reflection area (H31 in the drawing) where infrared rays are reflected by this reflection surface 304a is within a space S01 between the pair of chains 72.

[0132] The reflecting member 304 also has a pair of side plates 305 that sandwich the heater 306 from the depth direction of the device. The lower ends of the side plates 305 are positioned below the heater 306 in the vertical direction of the device.

[0133] Furthermore, the pair of side plates 305 are each formed with opposing surfaces 305a that face each other, and in the device depth direction, the pair of opposing surfaces 305a are disposed between the pair of chains 72 at a distance S01. The opposing surfaces 305a are an example of side surfaces.

[0134] The heater 306 is an infrared heater having a cylindrical outer shape, and is, for example, 30 mm away from the leading edge of the sheet material P being conveyed in the vertical direction. Furthermore, as shown in FIG. 11, the heater 306 has a cylindrical quartz tube 306a and a filament 306b disposed inside the quartz tube 306a and emitting infrared rays. Furthermore, a black coating is formed on the surface of the quartz tube 306a. The quartz tube 306a is an example of a heating unit.

[0135] In addition, in the depth direction of the device, the region (H33 in the drawing) in which the quartz tube 306a is arranged is contained within the space S01 between the pair of chains 72.

[0136] Furthermore, the wire mesh 312 is fixed to the edge of the reflecting member 304 by a fixing member (not shown), and separates the inside of the reflecting member 304 from the outside of the reflecting member 304, as shown in FIG.

[0137] (Action, Summary) In the fixing device 300 shown in FIG. 11, a voltage is applied to the filament 306b of the heater 306. The quartz tube 306a absorbs infrared rays emitted by the filament 306b to which the voltage is applied, causing the temperature to rise and the quartz tube 306a to radiate heat. The sheet material P conveyed by the rotating chain 72 is heated from above in a non-contact manner. By heating the sheet material P, the toner constituting the toner image transferred onto the sheet material P is softened.

[0138] Other functions are the same as those of the first embodiment except for those functions that are brought about by the presence of the heating plate 114.

[0139] Although the present invention has been described in detail with respect to a specific embodiment, it will be apparent to those skilled in the art that the present invention is not limited to such an embodiment and that various other embodiments are possible within the scope of the present invention. For example, although not specifically described in the above embodiment, other heating means such as a ceramic heater, a halogen heater, or an electric heating wire may be used as the heating section for heating the sheet member P.

[0140] In the first embodiment, the heating plate 114 is a plate member whose plate surface faces the sheet material P being transported, but it may be a wavy plate member. In this case, however, the effect achieved by having the plate surface facing the sheet material P being transported is not achieved.

[0141] Although not specifically described in the above embodiment, the opposing surfaces 105a and 305a may have a function of reflecting heat, which prevents the temperature inside the reflecting members 104 and 304 from decreasing, and effectively heats the sheet material P being conveyed.

[0142] Furthermore, in the above embodiment, the chain 72 is used as the circulating part, but it may be any endless part such as a wire.

[0143] Furthermore, in the above embodiment, the chain 72 is used as the circulating part, but it may be any endless part such as a wire.

[0144] In the first embodiment, the heating plate 114 is contained within the region H03 in the depth direction of the device, but it does not have to be contained within the region H03. In this case, however, the effect that would be obtained by containing the heating plate 114 within the region H03 does not occur. [Explanation of symbols]

[0145] 10 Image forming device 12 Image forming unit (an example of a forming unit) 68 Holding part 72 Chain (example of a circular part) 100 Fixing device 104 Reflective member (an example of a reflective part) 105a Opposing surface (an example of a side surface) 106 Heater (an example of a heat dissipation part) 108 Heat shielding material 114 Heating plate (an example of a heating part) 122 Conveyor 170 Spray unit (example of spray section) 210 Image forming device 300 Fixing device 304 Reflective member (an example of a reflective part) 305a Opposite surface (example of side surface) 306a Quartz tube (an example of a heating part)

Claims

1. a holding portion that extends in the width direction of the recording medium being conveyed and holds the recording medium; a pair of rotating parts attached to both ends of the holding part and rotating to transport the recording medium; a heating section that heats the recording medium without contact and is located between the pair of surrounding sections in the width direction; a blowing unit that blows air toward the recording medium, the blowing unit being located within the area in the width direction where the heating unit is disposed; A fixing device comprising:

2. The fixing device according to claim 1 , further comprising a reflective section arranged on the opposite side of the circulating section across the heating section when viewed from the width direction, the reflective area for reflecting heat rays being contained between the pair of circulating sections in the width direction.

3. The fixing device described in claim 2, wherein the reflective portion is U-shaped with the recording medium side open when viewed from the recording medium transport direction, and the reflective portion has sides that sandwich the heating portion from the width direction, and the sides are positioned between a pair of the circulating portions in the width direction.

4. A fixing device as described in any one of claims 1 to 3, comprising a heat-shielding section that faces the circulating section in a direction that intersects with the width direction when viewed from the conveying direction of the recording medium, and that is entirely positioned outside the area in which the heating section is positioned in the width direction.

5. The fixing device according to any one of claims 1 to 4, further comprising a pair of conveying sections arranged downstream of the heating section in the conveying direction of the recording medium, which convey the recording medium while rotating and sandwiching it between them, thereby heating the recording medium.

6. a forming unit for forming a toner image on a recording medium; a fixing device according to claim 5 for fixing a toner image onto a recording medium; An image forming apparatus comprising:

Images