Fixing device and image forming apparatus

Abstract

To prevent a harness connected to an electrical component inside a fixing rotator from being excessively heated.SOLUTION: A fixing device includes: a planar heater 24 (electrical component) which is installed in a hollow part of a fixing belt 21 (fixing rotator); a harness 61 which is connected to the planar heater 24; and a fixing upper cover 45 (fixing cover) which covers the fixing belt 21. The harness 61 extends from a portion connected with the planar heater 24 within the hollow part of the fixing belt 21 toward one end side in the width direction so as to be exposed to the outside of the fixing belt 21, is folded back on the outside and extends toward the other end side in the width direction between the fixing belt 21 and the fixing upper cover 45.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a fixing device that heats a toner image and fixes it on the surface of a sheet, and an image forming apparatus such as a copying machine, a printer, a facsimile machine, or a multifunction machine including the same.

Background Art

[0002] Conventionally, in a fixing device of an image forming apparatus such as a copying machine or a printer, a fixing rotating body such as a fixing belt having an electric component such as a heater thermistor installed inside (hollow portion) thereof is widely known (see, for example, Patent Document 1). And in such a fixing device, a harness (lead wire) for supplying electricity to the electric component is routed.

Summary of the Invention

Problems to be Solved by the Invention

[0003] In the conventional fixing device, the harness connected to the electric component inside the fixing rotating body has problems such as overheating and thermal damage, and a problem that the function of supplying electricity to the electric component deteriorates.

[0004] The present invention has been made to solve the above-described problems, and an object thereof is to provide a fixing device and an image forming apparatus in which a harness connected to an electric component inside a fixing rotating body is less likely to overheat.

Means for Solving the Problems

[0005] The fixing device in this invention includes a substantially cylindrical fixing rotating body that is heated by heating means to heat the toner image and fix it on the surface of the sheet, and has a hollow portion formed inside; a pressurizing rotating body that forms a nip portion where the sheet is conveyed by contacting the fixing rotating body; electrical components installed in the hollow portion of the fixing rotating body; a harness connected to the electrical components; and a fixing cover that covers the fixing rotating body. The harness extends from the portion connected to the electrical components in the hollow portion to one end side in the width direction so as to be exposed to the outside of the fixing rotating body, and is folded back outside, and is arranged to extend toward the other end side in the width direction between the fixing rotating body and the fixing cover or outside the fixing cover.

Advantages of the Invention

[0006] According to the present invention, it is possible to provide a fixing device and an image forming apparatus in which the harness connected to the electrical components inside the fixing rotating body is less likely to overheat.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

[0008] Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. In each figure, the same or corresponding parts are denoted by the same reference numerals, and the redundant description will be simplified or omitted as appropriate.

[0009] First, the overall configuration and operation of the image forming apparatus 100 will be described with reference to FIG. 1. In FIG. 1, 100 is a printer as an image forming apparatus, 1 is a photosensitive drum on which a toner image is formed on the surface, 6 is a process cartridge in which the photosensitive drum 1, a charging roller 4 (charging device), a developing device 5, and a cleaning device 2 are integrated, 7 is an exposure unit (writing unit) that irradiates the photosensitive drum 1 with exposure light L based on image information input from an input device such as a personal computer. Further, 9 is a transfer roller that transfers the toner image carried on the surface of the photosensitive drum 1 to the sheet P that is conveyed to the transfer nip portion (transfer position), and 12 is a paper feeding device (paper feeding cassette) that stores the sheet P such as paper. Further, 16 is a registration roller (timing roller) that conveys the sheet P toward the transfer nip portion where the photosensitive drum 1 and the transfer roller 9 are in contact, and 20 is a fixing device that fixes the unfixed image on the sheet P.

[0010] Here, around the photoreceptor drum 1, a charging roller 4 (charging device), a developing device 5, a cleaning device 2, etc. are arranged. And these members (the photoreceptor drum 1, the charging roller 4, the developing device 5, the cleaning device 2) are integrated as a process cartridge 6 and are detachably (replaceably) installed with respect to the image forming apparatus main body 100. The process cartridge 6 is taken out from the image forming apparatus main body 100 and replaced with a new one (or one that has been maintained) when a predetermined replacement cycle is reached or when maintenance is performed, etc.

[0011] Referring to FIG. 1, the operation during image formation (printing) in the image forming apparatus 100 will be described. First, when image information is transmitted from an input device such as a personal computer to the exposure unit 7 of the image forming apparatus 100, exposure light L (laser light) based on the image information is emitted from the exposure unit 7 toward the surface of the photoreceptor drum 1. On the other hand, the photoreceptor drum 1 is driven by a drive motor installed in the image forming apparatus main body 100 and rotates in the direction of the arrow (clockwise). And first, the surface of the photoreceptor drum 1 is uniformly charged at the position facing the charging roller 4 (this is the charging process). Thus, a charging potential (about -900 V) is formed on the photoreceptor drum 1. After that, the surface of the charged photoreceptor drum 1 reaches the irradiation position of the exposure light L. And the potential of the portion irradiated with the exposure light L becomes the latent image potential (about 0 to -100 V), and an electrostatic latent image is formed on the surface of the photoreceptor drum 1 (this is the exposure process).

[0012] After that, the surface of the photoreceptor drum 1 on which the electrostatic latent image is formed reaches the position facing the developing device 5. And toner is supplied from the developing device 5 onto the photoreceptor drum 1, and the latent image on the photoreceptor drum 1 is developed to form a toner image (this is the developing process). After that, the surface of the photoreceptor drum 1 after the developing process reaches the transfer nip portion (transfer position) with the transfer roller 9. Then, at the transfer nip portion with the transfer roller 9, a transfer bias (a bias having a polarity different from the polarity of the toner) is applied from the power supply unit to the transfer roller 9, and the toner image formed on the photoreceptor drum 1 is transferred onto the sheet P conveyed by the resist roller 16 (this is the transfer process).

[0013] Then, the surface of the photoreceptor drum 1 after the transfer process reaches the position facing the cleaning device 2. And at this position, the untransferred toner remaining on the photoreceptor drum 1 is mechanically removed by the cleaning blade 2a (see FIG. 2), and is collected into the cleaning device 2 (this is the cleaning process). Thus, a series of image forming processes on the photoreceptor drum 1 is completed.

[0014] On the other hand, the sheet P conveyed to the transfer nip portion between the photoreceptor drum 1 and the transfer roller 9 operates as follows. First, the uppermost sheet P stored in the sheet feeding device 12 is fed by the sheet feeding roller 15 toward the conveyance path. After that, the sheet P reaches the position of the resist roller 16. And the sheet P that has reached the position of the resist roller 16 is conveyed toward the transfer nip portion (the contact position between the transfer roller 9 and the photoreceptor drum 1) while adjusting the timing to align with the image formed on the photoreceptor drum 1.

[0015] Then, after the sheet P after the transfer process passes through the position of the transfer nip portion (transfer roller 9), it reaches the fixing device 20 through the conveyance path. The sheet P that has reached the fixing device 20 is fed between the fixing belt 21 and the pressure roller 31, and the image is fixed by the heat received from the fixing belt 21 and the pressure received from both members 21 and 31. The sheet P on which the image has been fixed is discharged from between the fixing belt 21 and the pressure roller 31 (this is the fixing nip portion), and then is discharged from the image forming apparatus main body 100 and placed on the paper discharge tray. In this way, a series of image forming processes (printing operations) are completed.

[0016] Next, with reference to FIGS. 2 to 4 and the like, the configuration and operation of the fixing device 20 installed in the image forming apparatus main body 100 will be described in detail. Referring to FIGS. 2 to 4 and the like, the fixing device 20 includes a fixing belt 21 as a fixing rotating body, a reinforcing member 30, a planar heater 24 as a heating means, a pressure roller 31 as a pressure rotating body, and the like.

[0017] Here, the fixing belt 21 as a fixing rotating body is an endless belt member that is externally tangent to the pressure roller 31 and rotates passively as the pressure roller 31 rotates. The fixing belt 21 is a thin and flexible endless belt that rotates (passively rotates) in the direction of the arrow in FIG. 2 (clockwise). The fixing belt 21 has a base material layer and a release layer sequentially laminated from the inner peripheral surface (the surface in sliding contact with the planar heater 24), and the overall thickness thereof is set to 1 mm or less. The base material layer of the fixing belt 21 has a layer thickness of 30 to 50 μm and is formed of a metal material such as nickel or stainless steel or a resin material such as polyimide. The release layer of the fixing belt 21 has a layer thickness of 5 to 50 μm and is formed of a material such as PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer), PTFE (polytetrafluoroethylene), polyimide, polyetherimide, PES (polyethersulfone), or the like. By providing the release layer, the releasability (peelability) with respect to the toner (toner image) is ensured. In this embodiment, the fixing belt 21 is formed by laminating a base material layer and a release layer, but an elastic layer can also be provided between the base material layer and the release layer.

[0018] The fixing belt 21 functions as a substantially cylindrical fixing rotating body having a hollow portion formed therein. Inside the fixing belt 21 (hollow portion), a planar heater 24 as an electrical component (power supply member), a holding member 23, a reinforcing member 30, and the like are installed. Here, the planar heater 24 is pressed against the pressure roller 31 via the fixing belt 21 inside (inner circumferential surface side) of the fixing belt 21 to form a nip portion (fixing nip) through which the sheet P is conveyed. That is, the planar heater 24 is installed so as to be in sliding contact with the inner circumferential surface of the fixing belt 21. And when the planar heater 24 is pressed against the pressure roller 31 via the fixing belt 21, a nip portion through which the sheet P is conveyed is formed. Thus, the planar heater 24 functions as a member (nip portion forming member) that forms the nip portion (fixing nip). Note that, in order to reduce the sliding resistance with the fixing belt 21, the surface of the planar heater 24 can be covered with a sheet-like member made of a low-friction material such as PTFE or provided with a surface layer. Note that a resistor pattern is formed on the portion of the planar heater 24 that is in sliding contact with the inner circumferential surface of the fixing belt 21. Then, power is supplied from a power supply unit (not shown) to the planar heater 24 (resistor pattern) via a harness 61 (see FIG. 5 etc.). By the resistor pattern generating heat due to its resistance, the fixing belt 21 is heated. Thus, the planar heater 24 also functions as a heating means for heating the fixing belt 21.

[0019] In the present embodiment, the planar heater 24 is held by a holding member 23 (holder). And as shown in FIG. 3, both end portions in the width direction (the direction perpendicular to the paper surface of FIG. 2 and the left-right direction of FIG. 3) of the holding member 23 holding the planar heater 24 are held by the frame 43 of the fixing device 20. Note that the harness 61 for supplying power to the planar heater 24 will be described in detail later with reference to FIGS. 5, 6, etc.

[0020] Thus, the fixing belt 21 is directly heated by the planar heater 24 installed inside it. And heat is applied to the toner image on the sheet P from the surface of the heated fixing belt 21. Incidentally, the output control of the planar heater 24 is performed based on the detection result of the temperature of the belt surface by a temperature detection sensor (not shown) such as a thermopile or a thermistor facing the surface of the fixing belt 21. Further, by controlling the output of such a planar heater 24, the temperature of the fixing belt 21 (fixing temperature) can be set to a desired temperature. Incidentally, in the present embodiment, instead of providing a temperature detection sensor that directly detects the surface temperature of the fixing belt 21 as described above, a temperature sensor that detects the surface temperature of the planar heater 24 is provided, and based on the detection result by the temperature sensor, the surface temperature (fixing temperature) of the fixing belt 21 is predicted (indirectly detected), and the output control of the planar heater 24 can also be performed.

[0021] Referring to FIG. 4, a pair of flange members 42 (guide members) guide both end portions in the width direction of the fixing belt 21 from the inner peripheral surface side so that the substantially cylindrical posture of the fixing belt 21 is maintained. Specifically, the two flange members 42 are formed of a heat-resistant resin material or the like and are respectively fitted into both end portions in the width direction of the frame 43 of the fixing device 20. The flange member 42 is provided with a guide portion 29a for holding the fixing belt 21 while maintaining the substantially cylindrical posture of the fixing belt 21, a stopper portion for restricting the movement of the fixing belt 21 in the width direction (belt deviation), and the like. Further, in the present embodiment, as shown in FIG. 3, the fixing belt 21 (and the planar heater 24 and the holding member 23) is configured to be pressed against the pressure roller 31 by the urging force of a compression spring 52 (urging member) via the flange member 42. Incidentally, the flange member 42 is arranged at both ends in the width direction in the circumferential direction excluding the nip portion so as not to interfere with the formation of the nip portion by the planar heater 24. Thus, in the present embodiment, the members that come into contact with the inner peripheral surface of the fixing belt 21 are only the flange members 42 that come into loose contact at both ends in the width direction and the planar heater 24, and there is no other member (belt guide) that comes into contact with the inner peripheral surface and guides the rotation of the fixing belt 21.

[0022] Here, in the present embodiment, the reinforcing member 30 is installed inside the fixing belt 21 so as to abut against the pressure roller 31 via the planar heater 24 (and the holding member 23) and the fixing belt 21. The reinforcing member 30 reinforces the strength of the planar heater 24 (and the holding member 23) that forms the nip portion, and is installed on the frame 43 by screw fastening or the like. Then, since the reinforcing member 30 abuts against the pressure roller 31 via the planar heater 24 (and the holding member 23) and the fixing belt 21, it suppresses the problem that the planar heater 24 (and the holding member 23) is greatly deformed under the pressure of the pressure roller 31 in the nip portion. In order to satisfy the above-described functions, the reinforcing member 30 is preferably formed of a metal material having high mechanical strength such as stainless steel or iron.

[0023] As the material for forming the holding member 23, a resin material or a metal material can be used, but it has rigidity such that it does not bend significantly even under the pressure of the pressure roller 31, and is a resin material having heat properties and heat insulation properties (liquid crystal polymer (LCP), polyamideimide (PAI), polyethersulfone (PES), polyphenylene sulfide (PPS), polyether nitrile (PEN), polyether ether ketone (PEEK), etc.).) is suitable. In the present embodiment, liquid crystal polymer (LCP) is used as the material of the holding member 23.

[0024] Referring to FIG. 2, the pressure roller 31 as a pressure rotating body has an elastic layer 33 provided on a core metal 32 (shaft portion), and is rotationally driven in a predetermined direction (counterclockwise in FIG. 2) by a drive motor (not shown). The core metal 32 of the pressure roller 31 is a hollow structure formed of a metal material. The elastic layer 33 of the pressure roller 31 is formed of a material such as foaming silicone rubber, silicone rubber, or fluororubber. Note that a thin release layer made of PFA, PTFE, or the like can also be provided on the surface layer of the elastic layer 33. The pressure roller 31 is pressed against the fixing belt 21 to form a desired nip portion between the two members. Also, referring to FIG. 3, a gear 49 that meshes with a drive gear (not shown) of a drive motor is installed on the pressure roller 31, and the pressure roller 31 is rotationally driven in the direction of the arrow (counterclockwise) in FIG. 2. Further, both end portions in the width direction of the pressure roller 31 are rotatably supported by the frame 43 of the fixing device 20 via bearings. In addition, in the present embodiment, the pressure roller 31 is a hollow structure, but the pressure roller 31 can also be a solid structure.

[0025] The fixing device 20 configured as described above is covered with a fixing cover (the fixing upper cover 45 and the fixing lower cover 46) as an exterior. Specifically, the fixing upper cover 45 functions as a fixing cover that covers the fixing belt 21 as a fixing rotating body, and is mainly formed so as to cover the side of the fixing belt 21 with respect to the nip portion (fixing nip). On the other hand, the fixing lower cover 46 is mainly formed so as to cover the side of the pressure roller 31 with respect to the nip portion (fixing nip). The fixing upper cover 45 and the fixing lower cover 46 are each a mold-formed product formed of a heat-resistant resin or the like, and are screwed to the frame 43 via a boss portion (not shown). In addition, in the present embodiment, the fixing cover is configured to be divided into two, the fixing upper cover 45 and the fixing lower cover 46, but the fixing cover can also be configured as one without being divided, or can be divided into three or more.

[0026] Hereinafter, the operation of the fixing device 20 configured as described above during printing will be briefly described. When the power switch of the image forming apparatus main body 100 is turned on, power is supplied to the planar heater 24, and the rotation drive of the pressure roller 31 in the direction of the arrow in FIG. 2 is started. As a result, due to the frictional force with the pressure roller 31 in the nip portion, the fixing belt 21 also rotates in a driven manner (rotates along) in the direction of the arrow in FIG. 2. Thereafter, the sheet P is fed from the paper feeding device 12, and an unfixed image is carried (transferred) onto the sheet P at the position of the transfer roller 9. The sheet P carrying the unfixed image (toner image) is conveyed in the direction of the arrow in FIG. 2 and fed into the nip portion of the fixing belt 21 and the pressure roller 31 in a pressure contact state. Then, due to the heating by the fixing belt 21 heated by the planar heater 24 and the pressing force between the planar heater 24 (and the holding member 23) reinforced by the reinforcing member 30 and the pressure roller 31, the toner image is fixed on the surface of the sheet P. Thereafter, the sheet P sent out from the nip portion is conveyed in the direction of the arrow.

[0027] Hereinafter, in the fixing device 20 (image forming apparatus 100) according to the present embodiment, the characteristic configuration and operation will be described in detail. As described above with reference to FIG. 2 and the like, the fixing device 20 is provided with a fixing belt 21 as a fixing rotating body, a pressure roller 31 as a pressing rotating body, a fixing upper cover 45 as a fixing cover, a planar heater 24 as an electrical component, a harness 61 for supplying power to the planar heater 24, and the like. The fixing belt 21 functions as a substantially cylindrical fixing rotating body that is heated by the planar heater 24 as a heating means to heat the toner image and fix it on the surface of the sheet P, and a hollow portion is formed inside. In particular, in the present embodiment, in order to improve the heating efficiency of the fixing belt 21, a fixing belt 21 having no elastic layer is used. The pressure roller 31 functions as a pressing rotating body that forms a nip portion through which the sheet P is conveyed by contacting the fixing belt 21 (fixing rotating body). The fixing upper cover 45 functions as a fixing cover that covers the fixing belt 21 (fixing rotating body).

[0028] Referring to FIGS. 5 and 6, the planar heater 24 is an electrical component installed in the hollow portion of the fixing belt 21 (fixing rotating body), and functions as a heating means for heating the fixing belt 21. The planar heater 24 in the present embodiment is divided into a plurality of parts in the width direction (the left-right direction in FIG. 5, which is the direction perpendicular to the paper surface in FIG. 6). Specifically, as shown in FIG. 5, the planar heater 24 includes a first divided planar heater 24A installed in the range M at the central portion in the width direction, and second divided planar heaters 24B installed in the ranges N at both ends in the width direction, respectively. Then, according to the size of the width direction of the sheet P conveyed to the nip portion (grasped based on the sheet information input by the user to the apparatus via the operation panel), power is supplied to all the divided planar heaters 24A and 24B, or power is supplied only to the first divided planar heater 24A, and switching control is performed. Note that the range M at the central portion in the width direction is a range that substantially coincides with the paper passing area of the sheet P having the minimum width direction size that can be conveyed to the nip portion (for example, A4 vertical size). And the range (N + M + N) obtained by adding the ranges N at both ends to this range M is a range that substantially coincides with the paper passing area of the sheet P having the maximum width direction size that can be conveyed to the nip portion (for example, A4 horizontal size). Also, in the present embodiment, the planar heater 24 is divided into three parts, but the number of divisions is not limited to this.

[0029] Referring to FIGS. 5 and 6, the harness 61 is electrically connected to the planar heater 24 as an electrical component (power supply member), and is for supplying the power supplied from the power supply installed in the image forming apparatus main body 100 to the planar heater 24. And as shown in FIG. 5, the harness 61 in the present embodiment extends to one end side in the width direction (the left side in FIG. 5) so as to be exposed to the outside of the fixing belt 21 (fixing rotating body) from the portion connected to the planar heater 24 (electrical component) in the hollow portion of the fixing belt 21, and is folded back outside, and is routed so as to extend toward the other end side in the width direction (the right side in FIG. 5) between the fixing belt 21 and the fixing upper cover 45 (fixing cover).

[0030] Specifically, the harness 61 in the present embodiment is formed by bundling split harnesses mainly divided into three parts, and its tip end branches into three parts inside the fixing belt 21 (hollow part) and is connected to three split surface heaters 24A and 24B respectively. Then, the harness 61 extends so as to come out from the inside of the fixing belt 21 to the outside of one end side in the width direction (the left side in FIG. 5), and forms a folded-back portion 61a outside. Then, the harness 61 passes between the fixing belt 21 (frame 43) and the fixing upper cover 45 from the folded-back portion 61a and extends toward the other end side in the width direction (the right side in FIG. 5). Then, the harness 61 is electrically connected to a connector 60 installed on the side surface of the other end portion in the width direction of the fixing device 20. This connector 60 is connected and disconnected from a main body side connector (a connector electrically connected to the power supply of the image forming apparatus 100, not shown) in conjunction with the attaching / detaching operation of the fixing device 20 with respect to the image forming apparatus 100. With such a configuration, the fixing device 20 mounted on the image forming apparatus main body 100 can receive and supply power to the surface heater 24 from the power supply of the image forming apparatus main body 100.

[0031] Thus, in the fixing device 20 in the present embodiment, the harness 61 is not routed in the shortest path from the portion connected to the surface heater 24 inside the fixing belt 21 toward the other end side in the width direction (the right side in FIG. 5, which is the side where the connector 60 is installed), but is routed in a roundabout way from the portion connected to the surface heater 24 inside the fixing belt 21 to the other end side in the width direction after being folded back at one end side in the width direction (the left side in FIG. 5) and passing between the fixing upper cover 45 and the fixing belt 21. Therefore, compared with the case where the harness 61 is routed in the shortest path, the problem that the harness 61 connected to the surface heater 24 inside the fixing belt 21 overheats is less likely to occur. Inside the fixing belt 21, the heat of the fixing belt 21 itself is likely to be trapped, and the temperature becomes higher compared to other parts. Therefore, the part of the harness 61 routed inside the fixing belt 21 is likely to reach a high temperature, and there is a high possibility that it will be thermally damaged or the function of supplying power to the planar heater 24 will deteriorate as it is. On the other hand, in the present embodiment, since the harness 61 is routed circuitously through a space (between the fixing belt 21 and the upper fixing cover 45) where the temperature is lower than inside the fixing belt 21, the heat of the part (the part inside the fixing belt 21) that has reached a high temperature of the harness 61 is transferred along the harness 61 to the lower temperature part (the part outside the fixing belt 21). Therefore, the overheating of the harness 61 inside the fixing belt 21 is reduced. In addition, due to such a mechanism, it is preferable to arrange the part of the harness 61 routed outside the fixing belt 21 (between the fixing belt 21 and the upper fixing cover 45) at a position as far as possible from the high-temperature fixing belt 21.

[0032] In particular, the fixing belt 21 in the present embodiment does not have an elastic layer provided, and compared with the one having an elastic layer provided between the base material layer and the release layer, the adhesion of the fixing belt 21 to the toner decreases. Therefore, in order to obtain a good fixing image, the fixing temperature is set on the high side, and the harness 61 also easily heats up. Thus, the configuration of the harness 61 in the present invention becomes useful. Further, the planar heater 24 in the present embodiment is divided into a plurality of parts in the width direction. In order to connect the harness 61 to at least the divided planar heater 24A at the center in the width direction, the connection part cannot be provided at the width direction end and must be provided at the center in the width direction. Therefore, at least the connection part at the center in the width direction (the space where heat is most likely to be trapped) is in a situation where it easily heats up, and the configuration of the harness 61 in the present invention becomes useful.

[0033] Here, referring to FIGS. 5, 6, etc., in the present embodiment, the fixing upper cover 45 as the fixing cover is arranged to be cooled by an air flow outside the fixing device 20 (the air flow indicated by the white arrow in FIG. 5). Specifically, referring to FIGS. 1, 5, and 6, the image forming apparatus main body 100 is provided with an intake fan 71 for taking in air from the outside (the front side of the apparatus) of the image forming apparatus 100 into the inside to cool the inside of the apparatus, and an exhaust fan 72 for discharging the hot air inside the image forming apparatus 100 to the outside (the back side of the apparatus). And these intake fan 71 and exhaust fan 72 function as fans for generating an air flow outside the fixing device 20. Specifically, the air sucked by the intake fan 71 flows so as to graze (touch the surface) the surface of the fixing upper cover 45. Also, the air flowing in such a manner is actively exhausted to the outside by the intake by the exhaust fan 72. By configuring in this way, since the portion of the harness 61 routed between the fixing belt 21 and the fixing upper cover 45 is actively cooled through the fixing upper cover 45, the heat of the portion of the harness 61 that has reached a high temperature (the portion inside the fixing belt 21) easily spreads along the harness 61 to that portion. Therefore, the over-temperature rise of the harness 61 inside the fixing belt 21 is further reduced.

[0034] Here, as shown in FIG. 6, in the present embodiment, when viewed in a cross-section orthogonal to the rotation center of the fixing belt 21 (fixing rotating body), the fan (particularly, the intake fan 71 that contributes greatly to the cooling of the fixing upper cover 45) is arranged at a position facing upward with respect to the fixing upper cover 45 (fixing cover). Further, when viewed in the above-described cross-section, the harness 61 is arranged at a position on the side of the intake fan 71 (in the range of the direction indicated by the white arrow in FIG. 6) with respect to a virtual line S2 orthogonal to a virtual straight line S1 connecting the center of the intake fan 71 (fan) and the rotation center of the pressure roller 31 (pressure rotating body). By setting the positional relationship in this way, the portion of the harness 61 routed between the fixing belt 21 and the upper fixing cover 45 will be located within the range of the upper fixing cover 45 cooled by the intake fan 71. Therefore, the effect of preventing the overheating of the harness 61 described above is more likely to be exerted.

[0035] Also, as shown in FIG. 5, in the present embodiment, the intake fan 71 (fan) is arranged to generate an air flow from one end side in the width direction (the left side in FIG. 5) toward the other end side in the width direction (the right side in FIG. 5). That is, the intake fan 71 is arranged on the side where the folded portion 61a is formed, rather than on the side where the connector 60 is installed. That is, the intake fan 71 is arranged so that the cooling efficiency on the side where the folded portion 61a is formed is increased. The heat of the portion of the harness 61 that has reached a high temperature within the fixing belt 21 is transmitted through the folded portion 61a and reaches the portion between the fixing belt 21 and the upper fixing cover 45. Therefore, by actively cooling the side of the folded portion 61a with the intake fan 71, the effect of preventing the overheating of the harness 61 described above is more likely to be exerted.

[0036] Here, referring to FIG. 5, in the present embodiment, the upper fixing cover 45 (fixing cover) has a plurality of ribs 45a (in the example of FIG. 5, five ribs 45a) that hold the harness 61 between the fixing belt 21 (fixing rotating body) formed at intervals in the width direction. Specifically, in the present embodiment, the plurality of ribs 45a are formed on the inner ceiling surface of the upper fixing cover 45 so as to be bent in a substantially "く" shape and protrude downward. And the harness 61 is held along the ceiling surface at the bent portion of the rib 45a. By providing the ribs 45a in this way, the posture of the harness 61 between the fixing belt 21 and the upper fixing cover 45 is determined, so that the effect of preventing the overheating of the harness 61 described above is more likely to be stably exerted. In particular, by bringing the portion routed outside the fixing belt 21 (between the fixing belt 21 and the fixing upper cover 45) in the harness 61 into contact with the fixing upper cover 45 directly cooled by the fan 71, the cooling efficiency of that portion is enhanced, and the effect of preventing overheating of the harness 61 is more likely to be exerted.

[0037] Here, the fixing upper cover 45 in the present embodiment is manufactured by resin mold forming. Therefore, in the manufacturing of the fixing upper cover 45, hole portions are formed in the ceiling portion (ceiling surface portion) where the ribs 45a are formed in order to secure the shape of the ribs 45a described above. The hole portions formed in the fixing upper cover 45 in this way may allow air to flow into the apparatus from outside the apparatus to some extent and hinder the heating efficiency of the fixing belt 21. And the heating efficiency of the fixing belt 21 tends to be lower in the range M at the center in the width direction than in the range N at both ends in the width direction. Therefore, the plurality of ribs 45a in the present embodiment are arranged such that the number arranged in the central portion in the width direction is less than the number arranged at the ends in the width direction. Specifically, in the example of FIG. 5, the number of ribs 45a in the range M at the center in the width direction is one, and the number of ribs 45a in the range N at both ends in the width direction is two on each side.

[0038] <Modification 1> As shown in FIGS. 7 and 8, the fixing device 20 in Modification 1 is different from that shown in FIGS. 5 and 6 in that the harness 61 is routed outside the fixing upper cover 45 instead of between the fixing upper cover 45 and the fixing belt 21. Specifically, the harness 61 extends from the portion connected to the planar heater 24 (electrical component) in the hollow portion of the fixing belt 21 to the outside of the fixing belt 21 (fixing rotating body) and extends to one end side in the width direction (the left side in FIG. 7), is folded back outside, and is routed so as to extend toward the other end side in the width direction (the right side in FIG. 7) outside the fixing upper cover 45 (fixing cover). In addition, a plurality of ribs 45a for holding the harness 61 are formed at intervals in the width direction on the outside (outer surface) of the fixing upper cover 45. Also in the fixing device 20 configured as described above, the harness 61 connected to the planar heater 24 (electrical component) inside the fixing belt 21 (fixing rotating body) is less likely to overheat. In particular, in the fixing device 20 in the first modification, since the portion of the harness 61 routed outside the fixing upper cover 45 is directly cooled by the air flow formed by the intake fan 71 (fan), the above-described effect is further significantly exhibited.

[0039] <First Modification> As shown in FIG. 9, also in the fixing device 20 in the second modification, as in the case of FIG. 6, when viewed in a cross section orthogonal to the rotation center of the fixing belt 21 (fixing rotating body), the harness 61 is located on the side of the intake fan 71 with respect to the virtual line S2 (in the range indicated by the white arrow in FIG. 9). Here, in the fixing device 20 in the second modification, when viewed in a cross section orthogonal to the rotation center of the fixing belt 21, the harness 61 is further located below the virtual horizontal line S3 passing through the rotation center of the fixing belt 21. Inside the fixing upper cover 45, the hot air rises. Therefore, the lower the harness 61 is disposed between the fixing belt 21 and the fixing upper cover 45, the less likely the harness 61 is to heat up. Therefore, by configuring as shown in FIG. 9, the effect of preventing overheating of the harness 61 is easily exhibited. Note that, as shown by the broken line in FIG. 9, also in the fixing device 20 in the second modification, as in the case of the first modification, the harness 61' can be routed outside the fixing upper cover 45 instead of between the fixing upper cover 45 and the fixing belt 21.

[0040] <Second Modification> As shown in FIG. 10, in the fixing device 20 in the second modification, the fixing upper cover 45 (fixing cover) is provided with an inlet side surface portion 45b, an outlet side surface portion 45c, a ceiling surface portion 45d, and an inclined surface portion 45e. The inlet side surface portion 45b stands up in a substantially vertical direction so as to face the fixing belt 21 (fixing rotating body) on the inlet side of the nip portion. The outlet side surface portion 45c stands up in a substantially vertical direction so as to face the fixing belt 21 on the outlet side of the nip portion. The ceiling surface portion 45d extends in a substantially horizontal direction so as to face the upper side of the fixing belt 21. The inclined surface portion 45e is inclined obliquely upward from the inlet side toward the outlet side so as to connect the upper end of the inlet side surface portion 45b and the inlet side end portion of the ceiling surface portion 45d. The outlet side end portion of the ceiling surface portion 45d is connected to the upper end of the outlet side surface portion 45c. And the harness 61 is arranged so as to extend from the portion folded back at one end side in the width direction toward the other end side in the width direction between the fixing belt 21 and the inclined surface portion 45e of the fixing upper cover 45. That is, in the harness 61, the portion routed outside the fixing belt 21 is routed between the fixing belt 21 and the inclined surface portion 45e of the fixing upper cover 45. Above the fixing device 20, water vapor generated from the sheet P, wax volatilized from the toner image on the sheet P, etc. are likely to occur. For these, an air flow generating means (for example, a fan) etc. is separately provided to generate an air flow from the upstream side (the right side in FIG. 10) to the downstream side (the left side in FIG. 10), and it is desired to discharge it outside the apparatus as much as possible. And, in order to form such an air flow smoothly, if the upper end of the inlet side surface portion 45b and the inlet side end portion of the ceiling surface portion 45d are directly connected, the air flow is obstructed by the inlet side surface portion 45b and the air flow is less likely to be exposed to the ceiling surface portion 45d (the cooling effect on the ceiling surface portion 45d by the air flow becomes low). On the other hand, in the example of FIG. 10, since the upper end of the inlet side surface portion 45b and the inlet side end portion of the ceiling surface portion 45d are connected via the inclined surface portion 45e, a smooth air flow as shown in FIG. 10 is formed. Therefore, in particular, the cooling effect on the inclined surface portion 45e by the air flow becomes high, and by arranging the harness 61 at this position, the effect of preventing the overheating of the harness 61 is easily exerted. Note that as shown by the dashed line in FIG. 10, also in the fixing device 20 in Modification 3, similar to that in Modification 1, the harness 61' can be routed outside the fixing upper cover 45 (the inclined surface portion 45e) instead of between the fixing upper cover 45 and the fixing belt 21.

[0041] <Modification 4> As shown in FIG. 11, the fixing device 120 in Modification 4 is of a heater-roller type, and a fixing roller 121 is used as the fixing rotating body, and a halogen heater 125 is used as the heating means. Specifically, the fixing roller 121 as the fixing rotating body is a roller member having a multilayer structure in which a coating layer (a layer in which an elastic layer and a release layer are laminated) is formed on a hollow-core metal material such as stainless steel, and is in pressure contact with the pressure roller 31 as the pressurizing rotating body to form a nip portion (fixing nip). The elastic layer in the coating layer 21b of the fixing roller 121 is formed of an elastic material such as fluororubber, silicone rubber, or foamed silicone rubber. The release layer in the coating layer 21b of the fixing roller 121 is formed of PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin) or the like. Inside the fixing roller 121 (hollow portion), a halogen heater 125 (electrical component) as the heating means is fixedly installed. Further, a harness 61 for supplying electricity to the halogen heater 125 as the electrical component is connected to the halogen heater 125. And the harness 61 extends so as to come out from the inside of the fixing roller 121 (fixing rotating body) to the outside on one end side in the width direction (the front side in the direction perpendicular to the paper surface of FIG. 11), and forms a folded-back portion 61a outside. Then, the harness 61 extends from the folded-back portion 61a through between the fixing roller 121 and the fixing upper cover 45 toward the other end side in the width direction (the back side in the direction perpendicular to the paper surface of FIG. 11). And the harness 61 is electrically connected to a connector 60 installed on the side surface of the other end portion in the width direction of the fixing device 20. The fixing device 120 configured as described above operates as follows. When the main switch of the apparatus main body 1 is turned on, an AC voltage is applied (power supplied) from the power supply of the image forming apparatus main body 100 to the halogen heater 125 via the harness 61. When a print command (print request) is input, the driving motor (driving mechanism) (not shown) starts driving the fixing roller 121 in the clockwise direction, and the driven rotation of the pressure roller 31 in the counterclockwise direction starts. Thereafter, the sheet P is fed from the paper feeding device 12, and at the position of the transfer roller 9, the toner image on the photosensitive drum 1 is carried as an unfixed image onto the sheet P. The sheet P carrying the unfixed image (toner image) is conveyed in the direction of the arrow in FIG. 11 and fed into the nip portion of the fixing roller 121 and the pressure roller 31 in a pressure contact state. Then, the toner image is fixed on the surface of the sheet P by the heating by the fixing roller 121 and the pressing force of the fixing roller 121 and the pressure roller 31. Then, the sheet P after the fixing process is sent out from the nip portion in the direction of the arrow by the rotating fixing roller 121 and pressure roller 31. Also in the fixing device 120 configured as described above, the harness 61 connected to the halogen heater 125 (electrical component) inside the fixing roller 121 (fixing rotating body) is less likely to overheat. As shown by the broken line in FIG. 11, also in the fixing device 120 in the fourth modification, the harness 61' can be routed outside the fixing upper cover 45 instead of between the fixing upper cover 45 and the fixing roller 121.

[0042] <Modification 5> As shown in FIG. 12, the fixing device 220 in the fifth modification is of an electromagnetic induction method (IH method), and an electromagnetic induction coil 250 is used as a heating means. Specifically, the electromagnetic induction coil 250 as a heating means is an electrical component installed so as to face the outer peripheral surface of the fixing belt 221 as a fixing rotating body, and the harness 61 is connected thereto. The electromagnetic induction coil 250 is integrally formed with a core, a coil guide, etc., and is formed by extending a litz wire obtained by bundling thin wires in the width direction so as to cover a part of the fixing belt 221. The coil guide is made of a highly heat-resistant resin material or the like and holds the electromagnetic induction coil 250 and the core. The core is a semi-cylindrical member made of a ferromagnetic material such as ferrite (the relative permeability is about 1000 to 3000), and a center core and side cores are provided to form efficient magnetic flux toward the fixing belt 221. The core is installed so as to face the electromagnetic induction coil 250 extending in the width direction. On the other hand, in addition to the base material layer, the elastic layer, and the release layer, a heating layer (for example, it can also be formed between the elastic layer and the release layer, or the base material layer can be used as the heating layer) that is electromagnetically induction-heated by the electromagnetic induction coil 250 is formed on the fixing belt 221. As the material of the heating layer, nickel, stainless steel, iron, copper, cobalt, chromium, aluminum, gold, platinum, silver, tin, palladium, an alloy composed of a plurality of these metals, etc. can be used. Inside the fixing belt 221, a nip portion forming member 226 that presses against the pressure roller 31 via the fixing belt 221 to form a nip portion (fixing nip) and a reinforcing member 223 that reinforces the strength of the nip portion forming member 226 are provided. The fixing device 220 configured as described above operates as follows. When the fixing belt 221 rotates in the direction of the arrow in FIG. 12 (clockwise), the fixing belt 221 is heated at the position facing the electromagnetic induction coil 250. Specifically, by passing a high-frequency alternating current through the electromagnetic induction coil 250, magnetic field lines are formed so as to alternately switch in both directions around the fixing belt 221. At this time, eddy currents are generated on the surface of the heating layer of the fixing belt 221, and Joule heat is generated due to the electrical resistance of the heating layer itself. Due to this Joule heat, the heating layer is electromagnetically induction-heated, and the fixing belt 221 is heated. Here, the upper fixing cover 45 as the fixing cover is configured to cover the electromagnetic induction coil 250 (electrical component) together with the fixing belt 221 (fixing rotating body). That is, the electromagnetic induction coil 250 is installed between the fixing belt 221 and the upper fixing cover 45. And the harness 61 extends from the portion connected to the electromagnetic induction coil 250 (electrical component) between the fixing belt 221 (fixing rotating body) and the upper fixing cover 45 (fixing cover) to one end side in the width direction, folds back at one end side in the width direction, and is arranged to extend toward the other end side in the width direction between the upper fixing cover 45 and the electromagnetic induction coil 250. In addition, in the fixing device 220, in order to configure the electromagnetic induction coil 250 as a unit to be relatively detachable, the upper fixing cover 45 can also be configured to be divided into one that covers the side of the electromagnetic induction coil 250 and one that covers the side of the fixing belt 221. Furthermore, in Modification 5, the upper fixing cover 45 is arranged to be cooled by the airflow outside the fixing device 220. That is, similar to the one in FIG. 5, the upper fixing cover 45 is configured to be cooled by the intake fan 71 (or the exhaust fan 72). Thereby, the harness 61 connected to the electromagnetic induction coil 250 (electrical component) between the fixing belt 221 and the upper fixing cover 45 (in the case of the electromagnetic induction coil 250 in the example of FIG. 12) is less likely to overheat. Since the electromagnetic induction coil 250 itself is likely to overheat and the inside of the coil case is likely to reach a high temperature, arranging the harness 61 in this way is useful. Note that, as shown by the dashed line in FIG. 12, in the fixing device 220 in Modification 5, the harness 61' can be routed outside the upper fixing cover 45 instead of between the upper fixing cover 45 and the electromagnetic induction heating coil 250.

[0043] <Modification 6> As shown in FIG. 13, in the fixing device 20 of Modification 6, the planar heater 24 is directly inserted into the power supply connector 66, and the resistor pattern of the planar heater 24 is in contact with the terminals of the power supply connector 66. Note that the planar heater 24 shown in FIG. 13 is formed so as to extend over the entire width direction without being divided in the width direction. Also, the power supply connector 66 is fixedly held by the fixing upper cover 45 and is electrically connected to the connector 60 via the harness 63. Thereby, power is supplied to the planar heater 24 from the power supply of the image forming apparatus main body 100 via the connector 60, the harness 63, and the power supply connector 66. On the other hand, in the hollow portion of the fixing belt 21, a thermostat 65 as an electrical component that functions as a safety device to prevent overheating of the planar heater 24 is installed so as to be in contact with the planar heater 24. One end side of this thermostat 65 is connected to the connector 60 via the first harness 61, and the other end side is connected to the power supply connector 66 via the second harness 62. And an electric circuit to which the thermostat 65 is connected is formed via the connector 60 electrically connected to the power supply of the image forming apparatus main body 100. And the harness 61 (first harness) extends from the portion connected to the thermostat 65 (electrical component) in the hollow portion of the fixing belt 21 to the outside of the fixing belt 21 (fixing rotating body) so as to be exposed to the outside at one end side in the width direction (the left side in FIG. 13), and is folded back outside, and is routed so as to extend toward the other end side in the width direction (the right side in FIG. 13) outside the fixing upper cover 45 (fixing cover). Also in the fixing device 20 configured as described above, the harness 61 connected to the thermostat 65 (electrical component) inside the fixing belt 21 (fixing rotating body) is less likely to overheat.

[0044] As described above, the fixing device 20 in the present embodiment is heated by the planar heater 24 (heating means) to heat the toner image and fix it on the surface of the sheet P, and includes a substantially cylindrical fixing belt 21 (fixing rotating body) having a hollow portion formed therein, and a pressure roller 31 (pressing rotating body) that forms a nip portion where the sheet P is conveyed by contacting the fixing belt 21. Further, a planar heater 24 (electrical component) installed in the hollow portion of the fixing belt 21, a harness 61 connected to the planar heater 24, and a fixing upper cover 45 (fixing cover) that covers the fixing belt 21 are provided. And the harness 61 extends to one end side in the width direction so as to be exposed to the outside of the fixing belt 21 from the portion connected to the planar heater 24 in the hollow portion of the fixing belt 21, and is folded back outside thereof, and is routed so as to extend toward the other end side in the width direction between the fixing belt 21 and the fixing upper cover 45 (or outside the fixing upper cover 45). Thereby, it becomes difficult for the harness 61 connected to the planar heater 24 (electrical component) to overheat inside the fixing belt 21 (fixing rotating body).

[0045] In the present embodiment, the pressure roller 31 is used as the pressing rotating body, but the pressing rotating body is not limited to these, and for example, a pressure belt can also be used as the pressing rotating body. Also, in the present embodiment, electrical components such as the planar heater 24 connected to the harness 61 are used as heating means for heating the fixing rotating body, but even if the electrical component and the heating means are separate, the present invention can be applied. And even in such cases, the same effects as those of the present embodiment can be obtained.

[0046] It should be noted that the present invention is not limited to the present embodiment, and it is obvious that the present embodiment can be appropriately changed within the scope of the technical idea of the present invention, in addition to what is suggested in the present embodiment. Also, the number, position, shape, etc. of the above-described constituent members are not limited to the present embodiment, and can be set to appropriate numbers, positions, shapes, etc. for implementing the present invention.

[0047] In the specification of the present application, the "sheet" is defined to include all sheet-like recording media such as coated paper, label paper, OHP sheets, and film sheets, in addition to paper.

Explanation of Signs

[0048] 1 Image forming apparatus (image forming apparatus main body), 20 Fixing device, 21 Fixing belt (fixing rotating body), 24 Planar heater (electrical component, power supply receiving member), 24A, 24B Divided planar heater, 31 Pressing roller (pressing rotating body), 45 Fixing upper cover (fixing cover), 45a Rib (holding part), 45b Inlet side surface part, 45c Outlet side surface part, 45d Ceiling surface part, 45e Tilted surface part, 46 Fixing lower cover, 61 Harness (conductive wire), 61a Folded-back part, 71 Intake fan (fan), 72 Exhaust fan (fan), S1 Virtual straight line, S2 Virtual line, S3 Virtual horizontal line, P Sheet (paper).

[0049] In addition, the aspects in the present invention can also be, for example, combinations of the following Supplementary Notes 1 to 13. (Supplementary Note 1) A substantially cylindrical fixing rotating body having a hollow part formed therein, which is heated by heating means to heat the toner image and fix it on the surface of the sheet, A pressing rotating body that forms a nip part where the sheet is conveyed by coming into contact with the fixing rotating body, An electrical component installed in the hollow part of the fixing rotating body, A harness connected to the electrical component, A fixing cover that covers the fixing rotating body, and The harness extends toward one end side in the width direction so as to be exposed to the outside of the fixing rotator from the portion connected to the electrical component in the hollow portion, is folded back outside, and is routed between the fixing rotator and the fixing cover or outside the fixing cover so as to extend toward the other end side in the width direction. A fixing device characterized by this. (Appendix 2) The fixing cover is arranged to be cooled by an air flow outside the fixing device. The fixing device according to Appendix 1, characterized by this. (Appendix 3) Equipped with a fan that generates the air flow, When viewed in a cross section orthogonal to the rotation center of the fixing rotator, The fan is arranged at a position facing upward with respect to the fixing cover, The harness is arranged on the fan side with respect to a virtual line orthogonal to a virtual straight line connecting the center of the fan and the rotation center of the pressurizing rotator. The fixing device according to Appendix 2, characterized by this. (Appendix 4) When viewed in a cross section orthogonal to the rotation center of the fixing rotator, the harness is arranged at a position below a virtual horizontal line passing through the rotation center of the fixing rotator. The fixing device according to Appendix 3, characterized by this. (Appendix 5) The fan is arranged to generate an air flow from the one end side in the width direction toward the other end side in the width direction. The fixing device according to Appendix 3 or Appendix 4, characterized by this. (Appendix 6) The fixing cover has a plurality of ribs for holding the harness formed at intervals in the width direction between or outside the fixing cover and the fixing rotator. The fixing device according to any one of Appendices 1 to 5, characterized by this. (Appendix 7) The plurality of ribs are arranged such that the number arranged at the center in the width direction is less than the number arranged at the end in the width direction. The fixing device according to Appendix 6, characterized by this. (Appendix 8) The fixing cover includes an inlet side surface portion facing the fixing rotating body on the inlet side of the nip portion, an outlet side surface portion facing the fixing rotating body on the outlet side of the nip portion, a ceiling surface portion facing above the fixing rotating body, and an inclined surface portion connecting the inlet side surface portion and the ceiling surface portion. The harness is arranged to extend from a portion folded back at one end in the width direction between the fixing rotating body and the inclined surface portion of the fixing cover or outside the inclined surface portion toward the other end in the width direction. The fixing device according to any one of Appendices 1 to 7, characterized in that. (Appendix 9) The fixing rotating body is a fixing belt having no elastic layer. The fixing device according to any one of Appendices 1 to 8, characterized in that. (Appendix 10) The electrical component is a planar heater as the heating means, The planar heater is divided into a plurality of parts in the width direction. The fixing device according to any one of Appendices 1 to 9, characterized in that. (Appendix 11) A fixing rotating body that is heated by heating means to heat the toner image and fix it on the surface of the sheet, A pressurizing rotating body that forms a nip portion through which the sheet is conveyed by contacting the fixing rotating body, A fixing cover that covers the fixing rotating body, An electrical component installed between the fixing rotating body and the fixing cover, A harness connected to the electrical component, Comprising, The harness extends from a portion connected to the electrical component between the fixing rotating body and the fixing cover to one end in the width direction, is folded back at one end in the width direction, and is arranged to extend toward the other end in the width direction between the fixing cover and the electrical component or outside the fixing cover. The fixing device is characterized in that. (Appendix 12) The fixing cover is arranged to be cooled by an air flow outside the fixing device. The fixing device according to Appendix 11, characterized in that. (Appendix 13) An image forming apparatus comprising a fixing device according to any one of Appendices 1 to 12.

Prior Art Documents

Patent Documents

[0050]

Patent Document 1

Claims

1. A substantially cylindrical fixing rotator that is heated by a heating means to heat a toner image and fix it on the surface of a sheet, and has a hollow portion formed inside; A pressurizing rotator that forms a nip portion where the sheet is conveyed by contacting the fixing rotator; Electrical components installed in the hollow portion of the fixing rotator; A harness connected to the electrical components; A fixing cover that covers the fixing rotator; Comprising: The harness extends to one end side in the width direction so as to be exposed to the outside of the fixing rotator from the portion connected to the electrical components in the hollow portion, is folded back outside, and is arranged to extend toward the other end side in the width direction between the fixing rotator and the fixing cover or outside the fixing cover. A fixing device characterized by this.

2. The fixing cover is arranged to be cooled by an air flow outside the fixing device. The fixing device according to claim 1, characterized by this.

3. Comprising a fan that generates the air flow, When viewed in a cross section orthogonal to the rotation center of the fixing rotator, The fan is arranged at a position facing upward with respect to the fixing cover, The harness is arranged at a position on the fan side with respect to a virtual line orthogonal to a virtual straight line connecting the center of the fan and the rotation center of the pressurizing rotator. The fixing device according to claim 2, characterized by this.

4. When viewed in a cross section orthogonal to the rotation center of the fixing rotator, the harness is arranged at a position below a virtual horizontal line passing through the rotation center of the fixing rotator. The fixing device according to claim 3, characterized by this.

5. The fan is arranged to generate an air flow from one end side in the width direction toward the other end side in the width direction. The fixing device according to claim 3, characterized by this.

6. The fixing cover has a plurality of ribs that hold the harness formed at intervals in the width direction, either between the fixing cover and the fixing rotator or outside. The fixing device according to claim 1 or claim 2, characterized by this.

7. The plurality of ribs are arranged such that the number arranged at the central portion in the width direction is less than the number arranged at the end portion in the width direction. The fixing device according to claim 6, characterized by this.

8. The fixing cover includes an inlet side surface portion facing the fixing rotator on the inlet side of the nip portion, an outlet side surface portion facing the fixing rotator on the outlet side of the nip portion, a ceiling surface portion facing above the fixing rotator, and an inclined surface portion connecting the inlet side surface portion and the ceiling surface portion. The harness is routed so as to extend from a portion folded back at one end side in the width direction between the fixing rotator and the inclined surface portion of the fixing cover or outside the inclined surface portion toward the other end side in the width direction. The fixing device according to claim 1 or claim 2, characterized in that.

9. The fixing rotator is a fixing belt having no elastic layer. The fixing device according to claim 1 or claim 2, characterized in that.

10. The electrical component is a planar heater as the heating means, The planar heater is divided into a plurality of parts in the width direction. The fixing device according to claim 1 or claim 2, characterized in that.

11. A fixing rotator that is heated by heating means to heat a toner image and fix it on the surface of a sheet, A pressurizing rotator that forms a nip portion through which the sheet is conveyed by contacting the fixing rotator, A fixing cover that covers the fixing rotator, An electrical component installed between the fixing rotator and the fixing cover, A harness connected to the electrical component, Comprising, The harness extends from a portion connected to the electrical component between the fixing rotator and the fixing cover to one end side in the width direction, is folded back at one end side in the width direction, and is routed so as to extend toward the other end side in the width direction between the fixing cover and the electrical component or outside the fixing cover. The fixing device is characterized by this.

12. The fixing cover is arranged to be cooled by an air flow outside the fixing device. The fixing device according to claim 11, characterized in that.

13. An image forming apparatus, characterized in that it includes the fixing device according to claim 1 or claim 2.

Images