Detachable unit, fixing device, and image forming apparatus

Abstract

To enable easy attachment and detachment of the detachable unit to the main device body without increasing size or cost. [Solution] A fixing device 20 (detachable unit) is detachably installed on an image forming apparatus 100 (apparatus body), and is provided with an exterior-also serving frame 60 (exterior) made of a metal material. Furthermore, gripping portions 61a and 62a made of a material with lower thermal conductivity than the exterior-also serving frame 60 are formed so as to be exposed on a part of the outer surface of the exterior-also serving frame 60.

Description

Technical Field

[0001] The present invention relates to a detachable unit such as a fixing device detachably installed in a device such as an image forming apparatus, a fixing device as the detachable unit, and an image forming apparatus such as a copying machine, a printer, a facsimile machine, or a multifunction machine including them.

Background Art

[0002] Conventionally, in devices such as image forming apparatuses like copying machines and printers, there are known ones in which detachable units such as a fixing device and a paper conveyance device are detachably installed (see, for example, Patent Documents 1 and 2). And in Patent Documents 1 and 2, the detachable unit has a handle (gripping part) formed on an exterior made of a resin material that covers the whole. And users and service technicians hold the handle to take out the detachable unit from the apparatus main body or attach the detachable unit to the apparatus main body to perform maintenance and replacement of the detachable unit.

Summary of the Invention

Problems to be Solved by the Invention

[0003] Since the conventional detachable unit has a gripping part (handle) provided on the exterior, the detaching and attaching operation with respect to the apparatus main body could be easily performed. However, since such a detachable unit is covered with an exterior molded entirely from a resin material, the detachable unit has become larger and more costly accordingly. In particular, for a detachable unit that does not assume a detaching and attaching operation by a user and only assumes a detaching and attaching operation by a service technician, the configuration of the exterior as described above has been an excessive specification.

[0004] The present invention has been made to solve the above-described problems, and an object thereof is to provide a detachable unit, a fixing device, and an image forming apparatus that can easily perform a detaching and attaching operation with respect to an apparatus main body without increasing the size and cost. [Means for solving the problem]

[0005] The detachable unit in this invention is a detachable unit that is detachably installed on the main body of the device, and comprises an exterior made of a metal material and a gripping portion made of a material with lower thermal conductivity than the exterior, and formed to be exposed on a part of the outer surface of the exterior. [Effects of the Invention]

[0006] According to the present invention, it is possible to provide a detachable unit, a fixing device, and an image forming apparatus that can be easily attached to and detached from the main body of the apparatus without increasing size or cost. [Brief explanation of the drawing]

[0007] [Figure 1] This is an overall configuration diagram showing an image forming apparatus according to an embodiment of the present invention. [Figure 2] This is a perspective view showing the procedure for opening the cover of an image forming apparatus. [Figure 3] This is a diagram showing the configuration of the fixing device. [Figure 4] This is a top view of the fixing device as seen in the width direction. [Figure 5] This is a schematic side view showing the anchoring belt and guide member in the width direction. [Figure 6] (A) A perspective view of the fixing device from above, and (B) A perspective view of the fixing device from below. [Figure 7] (A) A top view showing the fixing device, and (B) A bottom view showing the fixing device. [Figure 8] This is a schematic diagram showing the state in which the fixing device is being held. [Figure 9] This is a side view showing the fixing device. [Figure 10] (A) A top view and (B) A bottom view show a modified fixing device. [Modes for carrying out the invention]

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

[0009] First, Figure 1 will explain the overall configuration and operation of the image forming apparatus 100 as a device. In Figure 1, 100 represents a small printer as an image forming apparatus, 1 represents a photosensitive drum on which a toner image is formed, 6 represents a process cartridge that integrates the photosensitive drum 1, a charging roller 4, a developing device 5, and a cleaning device 2, and 7 represents an exposure device (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. Furthermore, 9 is a transfer roller that transfers the toner image supported on the surface of the photoreceptor drum 1 to the sheet P that is transported to the transfer nip section (transfer position), 12 is a paper feed device (paper feed cassette) that stores the sheet P such as paper, and 16 is a register roller (timing roller) that transports the sheet P toward the transfer nip section where the photoreceptor drum 1 and the transfer roller 9 come into contact. Furthermore, 20 indicates a fixing device as a detachable unit for fixing the unfixed image on sheet P, and 120 indicates a fan that generates airflow above the fixing device 20.

[0010] Here, a charging roller 4, a developing device 5, a cleaning device 2, and other components are arranged around the photoreceptor drum 1. These components (photoreceptor drum 1, charging roller 4, developing device 5, and cleaning device 2) are integrated as a process cartridge 6 and are installed in a detachable (replaceable) manner on the image forming apparatus body 100 (apparatus body). The process cartridge 6 is mainly removed from the image forming apparatus body 100 by the user and replaced with a new one when it reaches a predetermined replacement cycle.

[0011] Furthermore, the fixing device 20 is installed in a manner that allows it to be detached (replaced and maintained) from the main body of the image forming apparatus 100, which is the main body of the apparatus. In this embodiment, the image forming apparatus 100 is a small printer, and, in principle, it is not intended for the user to access the inside of the image forming apparatus 100 to perform work, except for replacing the process cartridge 6 and jamming (removing sheets P that have stopped being transported). Furthermore, the lifespan of the fuser unit 20 is set to be approximately the same as the lifespan of the image forming apparatus 100. Therefore, the operation of attaching and detaching the fuser unit 20 to the image forming apparatus body 100 (device body) is mainly limited to when a service technician performs maintenance (including replacement) in the event of a fuser unit 20 failure, and it is not intended for the user to perform the attachment and detachment operation of the fuser unit 20. Referring to Figures 1 and 2, the fixing device 20 (detachable unit) is attached and detached when the opening / closing cover 110 (which is installed on the image forming apparatus body 100 so as to be rotatable around the shaft portion 110a) of the image forming apparatus body 100 (apparatus body) is open.

[0012] Referring to Figure 1, the operation of the image forming apparatus 100 during normal image formation will be described. First, when image information is transmitted from an input device such as a personal computer to the exposure device 7 of the image forming apparatus 100, the exposure device 7 emits exposure light L (laser light) based on that image information toward the surface of the photoreceptor drum 1. Meanwhile, the photoreceptor drum 1 is driven by a drive motor installed in the image forming apparatus body 100 and rotates in the direction of the arrow (clockwise). First, the surface of the photoreceptor drum 1 is uniformly charged at the position opposite the charging roller 4 (this is the charging process). In this way, a charge potential (approximately -900V) is formed on the photoreceptor drum 1. Subsequently, the charged surface of the photoreceptor drum 1 reaches the irradiation position of the exposure light L. Then, the potential of the part irradiated by the exposure light L becomes the latent image potential (approximately 0 to -100V), and an electrostatic latent image is formed on the surface of the photoreceptor drum 1 (this is the exposure process).

[0013] After that, the surface of the photosensitive drum 1 on which the electrostatic latent image has been formed reaches the position facing the developing device 5. Then, toner is supplied onto the photosensitive drum 1 from the developing device 5, and the latent image on the photosensitive drum 1 is developed to form a toner image (this is the developing process). After that, the surface of the photosensitive 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 that of the toner) is applied to the transfer roller 9 from the power supply unit, and the toner image formed on the photosensitive drum 1 is transferred onto the sheet P conveyed by the resist roller 16 (this is the transfer process).

[0014] Then, the surface of the photosensitive drum 1 after the transfer process reaches the position facing the cleaning device 2. And at this position, the untransferred toner remaining on the photosensitive drum 1 is mechanically removed by the cleaning blade and collected into the cleaning device 2 (this is the cleaning process). Thus, a series of image forming processes on the photosensitive drum 1 is completed.

[0015] On the other hand, the sheet P conveyed to the transfer nip portion between the photosensitive 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 photosensitive drum 1) while adjusting the timing to align with the image formed on the photosensitive drum 1.

[0016] After that, the sheet P after the transfer process passes through the position of the transfer nip portion (transfer roller 9) and then 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 the image forming apparatus main body 100 after being sent out from between the fixing belt 21 and the pressure roller 31 (which is the fixing nip), and is placed on the paper discharge tray. Thus, a series of image forming processes is completed.

[0017] Next, with reference to FIGS. 3 to 5 and the like, the configuration and operation of the fixing device 20 as a detachable unit that is detachably installed in the image forming apparatus main body 1 as the apparatus main body will be described. The fixing device 20 is a device that conveys the sheet P (a sheet carrying unfixed toner) while heating it. Referring to FIG. 3 and the like, the fixing device 20 includes a fixing belt 21 as a fixing rotating body, a planar heater 24 as a heat source (heating means), a holder 23, a stay 30, a thermistor 40, a pressure roller 31 as a pressure rotating body, an inlet guide plate 59, a fixing side conveyance guide member 61 (an outlet upper guide member), a pressure side conveyance guide member (an outlet lower guide member), an exterior and housing combined frame 60 that functions as both an exterior and a housing, and the like.

[0018] Here, the fixing belt 21 as a fixing rotating body is an endless belt member that is externally circumscribed around 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. 3 (clockwise). The fixing belt 21 has a base material layer, an elastic layer, and a release layer sequentially laminated from the inner peripheral surface (the surface that slides against 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 elastic layer of the fixing belt 21 has a layer thickness of 100 to 300 μm and is made of a rubber material such as silicone rubber, foamed silicone rubber, or fluororubber. By providing an elastic layer, minute irregularities are not formed on the surface of the fixing belt 21 at the fixing nip, heat is uniformly transferred to the toner image on the sheet P, and the occurrence of orange peel-like images is suppressed. The release layer of the fixing belt 21 has a layer thickness of 5 to 50 μm and is made of materials such as PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer), PTFE (polytetrafluoroethylene), polyimide, polyetherimide, and PES (polyethersulfone). By providing a release layer, release properties (peelability) from toner (toner image) are ensured. In this embodiment, an elastic layer is formed on the fixing belt 21, but it is also possible to use a belt in which a release layer (surface layer) is formed on the base material layer without an elastic layer.

[0019] On the inside (inner circumferential surface) of the fixing belt 21, a planar heater 24, a holder 23, a stay 30, a thermistor 40, etc., are installed. Here, the planar heater 24 is arranged to extend in the width direction (the direction perpendicular to the plane of the paper in Figure 3, the left-right direction in Figures 4 and 5, and the ±Y direction). The planar heater 24 is pressed against the pressure roller 31 via the fixing belt 21 on the inside (inner circumferential surface side) of the fixing belt 21, forming a nip section (fixing nip) on which the sheet P is conveyed. That is, the planar heater 24 is installed so as to slide against the inner circumferential surface of the fixing belt 21. The planar heater 24 presses against the pressure roller 31 via the fixing belt 21, thereby forming a nip section on which the sheet P is conveyed. In this way, the planar heater 24 functions as a member that forms a nip section (fixing nip) (nip section forming member). In addition, to reduce 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 a surface layer can be provided. Furthermore, the planar heater 24 has a resistive pattern (heat-generating resistor) formed on the portion that slides against the inner circumferential surface of the fixing belt 21. Power is supplied to the resistive pattern from a power supply unit (not shown), and the resistive pattern generates heat due to its resistance, thereby heating the fixing belt 21. In this way, the planar heater 24 also functions as a heat source (heating means) for heating the fixing belt 21.

[0020] In this embodiment, the planar heater 24 is held by the holder 23 (holding member). The holder 23 has a recess formed therein, into which the planar heater 24 is fitted, thereby holding the planar heater 24 across its width. The holder 23 is held by the stay 30 while holding the planar heater 24. The stay 30, which holds the planar heater 24 and the holder 23, is held at both ends in the width direction by flange members 42 to the exterior frame 60 of the fixing device 20 (see Figure 4, etc.).

[0021] In this way, the fuser belt 21 is directly heated by a planar heater 24 (resistor pattern) installed inside it. Then, heat is applied to the toner image on the sheet P from the surface of the heated fuser belt 21. Here, the output control of the planar heater 24 is performed based on the temperature detection result by the thermistor 40, which is in direct (or indirectly via another component) contact with the planar heater 24. In this embodiment, there is no temperature sensor that directly detects the surface temperature of the fixing belt 21. Instead, the temperature of the planar heater 24 is controlled by the thermistor 40, thereby indirectly controlling the surface temperature (fixing temperature) of the fixing belt 21 to reach a desired temperature.

[0022] Referring to Figure 5, the pair of flange members 42 guide both ends of the fixing belt 21 in the width direction from the inner circumferential surface side so that the fixing belt 21 maintains a substantially cylindrical position. More specifically, the two flange members 42 are made of a heat-resistant resin material or the like, and are held at both ends in the width direction of the outer frame 60 of the fixing device 20 so as to be slidable in the direction of forming a nip portion (fixing nip). The flange members 42 are provided with a guide portion 42a for holding the fixing belt 21 while maintaining the substantially cylindrical posture of the fixing belt 21, and a stopper portion for restricting the movement of the fixing belt 21 in the width direction (towards the belt), etc. Furthermore, in this embodiment, as shown in Figure 4, the fixing belt 21 (and the planar heater 24 and holder 23) are configured to be pressed against the pressure roller 31 by pressure applied by the pressure lever 52 (pressure mechanism 51) via the flange member 42. Furthermore, the flange members 42 are positioned at both ends in the width direction, within the circumferential range excluding the fixing nip, so as not to interfere with the formation of the fixing nip by the planar heater 24. Furthermore, in this embodiment, the only members that contact the inner circumferential surface of the fixing belt 21 are the flange members 42 that make loose contact at both ends in the width direction and the planar heater 24, and there are no other members (belt guides) that contact the inner circumferential surface and guide the rotation of the fixing belt 21.

[0023] In this embodiment, the stay 30 is installed inside the fixing belt 21 so as to contact the pressure roller 31 via the planar heater 24 (and holder 23) and the fixing belt 21. The stay 30 reinforces the strength of the planar heater 24 (and holder 23) that forms the fixing nip, and is installed on the exterior frame 60 (or holder 23) by screw fastening or the like. Furthermore, the stay 30 contacts the pressure roller 31 via the planar heater 24 (and holder 23) and the fixing belt 21, thereby preventing the planar heater 24 (and holder 23) from deforming significantly in the fixing nip due to the pressure applied by the pressure roller 31. In order to satisfy the above-mentioned function, it is preferable that the stay 30 be made of a metal material with high mechanical strength, such as stainless steel or iron.

[0024] While resin materials and metal materials can be used to form the holder 23, a resin material (such as liquid crystal polymer (LCP), polyamide-imide (PAI), polyethersulfone (PES), polyphenylene sulfide (PPS), polyethernitrile (PEN), polyetheretherketone (PEEK), etc.) is preferred as it has sufficient rigidity to prevent excessive deflection even under pressure from the pressure roller 31, and possesses thermal and heat insulating properties. In this embodiment, liquid crystal polymer (LCP) is used as the material for the holder 23.

[0025] Referring to Figure 3, the pressure roller 31, which acts as a pressurizing rotating body, has an elastic layer 33 provided on a core metal 32 (shaft portion), and is driven to rotate in a predetermined direction (counterclockwise in Figure 3) by a drive motor 95. The core metal 32 of the pressure roller 31 is a hollow structure made of a metal material. The elastic layer 33 of the pressure roller 31 is made of a material such as foamed silicone rubber, silicone rubber, or fluororubber. A thin release layer made of PFA, PTFE, etc. can also be provided on the surface of the elastic layer 33. The pressure roller 31 is pressed against the fixing belt 21 to form a desired nip portion (fixing nip) between the two members. Also, referring to Figure 4, a gear 45 that meshes with the drive gear of the drive motor is installed on the pressure roller 31, and the pressure roller 31 is driven to rotate in the direction of the arrow in Figure 3 (counterclockwise). Furthermore, both ends of the pressure roller 31 in the width direction are rotatably supported by bearings on the outer frame 60 of the fixing device 20.

[0026] The following briefly describes the normal operation of the fixing device 20 configured as described above. When a print request is received by the main unit 100, power is supplied to the planar heater 24, and the drive motor 95 starts rotating the pressure roller 31 in the direction of the arrow in Figure 3. As a result, the fixing belt 21 also rotates in the direction of the arrow in Figure 3 due to the frictional force between the fixing nip and the pressure roller 31. Subsequently, the sheet P is fed from the paper feeder 12, and the unfixed image is placed (transferred) onto the sheet P at the position of the transfer roller 9. The sheet P, on which the unfixed image (toner image) is placed, is guided by the entrance guide plate 59 and transported in the direction of arrow Y10 in Figure 3, and is fed into the nip section (fixing nip) of the fixing belt 21 and pressure roller 31, which are in a pressed state. Then, the toner image is fixed to the surface of the sheet P by heating from the fixing belt 21 heated by the planar heater 24, and by the pressing force between the planar heater 24 (and holder 23), reinforced by the stay 30, and the pressure roller 31. After that, the sheet P, which has been fed out from the fixing nip, is conveyed in the direction of arrow Y11.

[0027] The configuration and operation of the fixing device 20, which serves as a characteristic attachment / detachment unit in the image forming apparatus 100 of this embodiment, will be described in detail below. In this embodiment, the fixing device 20 functions as a detachable unit that is detachably installed on the image forming apparatus body 100, which is the main body of the apparatus. Furthermore, as explained earlier using Figures 1 and 2, the attachment and detachment of the fixing unit 20 is mainly limited to when a service technician performs maintenance (including replacement) on the fixing unit 20, and it is not intended for the user to perform the attachment and detachment of the fixing unit 20. Specifically, the attachment and detachment of the fixing unit 20 is performed with the opening / closing cover 110 of the image forming apparatus body 100 open.

[0028] Referring to Figures 3 and 6, the fixing device 20 (detachable unit) in this embodiment is covered with an exterior-also serving frame 60 made of a metal material such as stainless steel. Specifically, the fixing device 20 is generally covered by an exterior-mounted frame 60, except for the inlet portion into which the sheet P is fed (where the inlet guide plate 59 is installed) and the outlet portion from which the sheet P is discharged (where the fixing-side transport guide member 61 and the pressurizing-side transport guide member 62 are installed). Furthermore, this exterior-mounted frame 60 also functions as the housing (structure) of the fixing device 20 (detachable unit), and as explained earlier using Figure 4, it rotatably holds the fixing belt 21 (fixing rotating body) and the pressure roller 31 (pressure rotating body).

[0029] Thus, in this embodiment, the fixing device 20 uses a metal frame 60 that also serves as the housing as its exterior. Compared to cases where a molded resin material is used for the exterior, the fixing device 20 can be made smaller and less expensive. However, since the fixing device 20 has a heat source (planar heater 24) installed inside, if a metal frame 60 that also serves as the exterior is used as the exterior, the exterior is more likely to reach high temperatures compared to when a resin material is used as the exterior. Therefore, when removing the fixing device 20 from the image forming apparatus body 100 immediately after use, the operator will be gripping the hot frame 60 (exterior), and care must be taken to avoid burns.

[0030] Therefore, in this embodiment, in order to solve such problems, as shown in Figures 6 and 7, gripping portions 61a and 62a made of a material with lower thermal conductivity than the exterior-also-frame 60 (exterior) (in this embodiment, a heat-resistant resin material) are formed so as to be exposed on a part of the outer surface of the exterior (the part that functions as the exterior in the exterior-also-frame 60). Then, as shown by the dashed lines in Figure 8 (not a proportional scale), the worker will perform the attachment and detachment of the fixing device 20 while gripping the gripping parts 61a and 62a. Therefore, compared to the case where the worker grips the exterior / frame 60, which has reached a high temperature, to perform the attachment and detachment of the fixing device 20, the worker can perform the attachment and detachment work in a state where they feel less heat (improving the ease of attachment and detachment). In particular, since the fixing device 20 in this embodiment is intended to be attached and detached only by service personnel who are familiar with handling the device, it is expected that the attachment and detachment work can be performed without errors by gripping the gripping parts 61a and 62a without touching the outer frame 60. As a result, the fixing device 20 can be easily attached to and detached from the image forming apparatus body 100 without increasing the size or cost of the fixing device 20.

[0031] In this embodiment, the gripping portions 61a and 62a, which are made of a low thermal conductivity material that does not easily become hot, are formed on the fixing-side transport guide member 61 and the pressurizing-side transport guide member 62, respectively, which guide the sheet P that is fed out from the nip portion (fixing nip). More specifically, as shown in Figures 6 and 7, the fixing-side transport guide member 61 is positioned on the side of the fixing belt 21 (fixing rotating body) and inside the outer casing / combined frame 60 (outer casing) so that its main part is not exposed from the outer casing / combined frame 60. In contrast, the pressure-side transport guide member 62 is positioned on the side of the pressure roller 31 (pressure rotating body) and inside the outer casing / combined frame 60 (outer casing) so that its main part is not exposed from the outer casing / combined frame 60. Furthermore, the gripping portions 61a and 62a are integrally formed on the fixing-side transport guide member 61 and the pressurizing-side transport guide member 62, respectively, so that they are exposed on the outer surface of the outer frame 60 (outer casing) (allowing the operator to grip them).

[0032] More specifically, the fixing device 20 (attachment / detachment unit) is formed in a roughly rectangular shape and is attached to and detached from the image forming apparatus body 100 (apparatus body) with the shorter side (±X direction) as the attachment / detachment direction. The gripping portions 61a and 62a are formed on the upper surface 60a and lower surface 60b of the exterior-mountable frame 60 (exterior), respectively, on the downstream side in the mounting direction (the front side in the mounting direction, which is in the +X direction). Specifically, the upper gripping portion 61a, which is formed to protrude from the upper part of the anchoring-side transport guide member 61, is formed on the downstream side (+X direction) of the mounting direction on the upper surface 60a of the outer casing frame 60, and is intended to be supported by the operator's thumb. In contrast, the lower gripping portion 62a, which is formed to protrude from the lower part of the pressurizing-side transport guide member 62, is formed on the downstream side (+X direction) of the mounting direction on the lower surface 60b of the outer casing frame 60, and is intended to support most of the load with the operator's four fingers other than the thumb. Furthermore, the upper surface 60a and lower surface 60b of the exterior-mounted frame 60 are formed with notches (or holes) to expose the gripping portions 61a and 62a, respectively.

[0033] Furthermore, the fixing device 20 in this embodiment is designed to be held by the operator with both hands while the attachment and detachment work is performed. Therefore, as shown in Figures 6 and 7, the gripping portions 61a and 62a are formed by dividing them into two sections at approximately equal distances from the approximate center position in the longitudinal direction (±Y direction) (the position indicated by the dashed line in Figure 7). As a result, the worker will hold the left gripping parts 61a and 62a with their left hand and the right gripping parts 61a and 62a with their right hand in a balanced manner when attaching and detaching the fixing device 20.

[0034] Referring to Figure 3, in this embodiment, the anchoring-side transport guide member 61 is fastened to the upper surface 60a of the outer casing frame 60 (outer casing) by a plurality of screws 90. Similarly, the pressurized transport guide member 62 is fastened to the lower surface 60b of the outer casing frame 60 (outer casing) by a plurality of screws 90. In this way, by fixing the transport guide members 61 and 62 to the exterior-mounted frame 60, which also functions as an enclosure, it becomes easier to determine the position in which the transport guide members 61 and 62, which guide the transport of the sheet P, can be reliably positioned. In this embodiment, the transport guide members 61 and 62 are fixed to the exterior frame 60 using screws 90. However, the method of fixing the transport guide members 61 and 62 is not limited to this, and for example, snap fasteners can also be used. Furthermore, referring to Figure 2(B) (and Figure 6), in this embodiment, the fixing device 20 is fastened to the main body side plate (main body housing) of the image forming apparatus body 100 by screws 91 on the downstream side (front side in the mounting direction). Therefore, when an operator attaches or detaches the fixing device 20, the screws 91 are screwed in and unscrewed at the same time.

[0035] Furthermore, referring to Figure 7 (and Figure 6), in this embodiment, the gripping portions 61a and 62a have multiple ribs 61a2 and 62a2 extending in the longitudinal direction (±Y direction) and spaced apart in the short direction (attachment / detachment direction, ±X direction). These ribs 61a2 and 62a2 are integrally formed as part of the gripping portions 61a and 62a when the transport guide members 61 and 62 are injection molded. Furthermore, by providing these ribs 61a2 and 62a2 on the gripping parts 61a and 62a, the fingers are less likely to slip when the worker grips the gripping parts 61a and 62a, improving grip strength (ease of attachment and detachment).

[0036] Furthermore, referring to Figure 7 (and Figure 6), in this embodiment, the gripping portions 61a and 62a have edges 61a1 and 62a2 that protrude upward on the upper surface 60a of the outer casing frame 60 (outer casing) and protrude downward on the lower surface 60b of the outer casing frame 60, except for the downstream side (+≡ direction) in the mounting direction. The edge portion 61a1 formed on the upper gripping portion 61a is roughly U-shaped when viewed from above and is formed to protrude upward from the other parts. Similarly, the edge portion 62a1 formed on the lower gripping portion 62a is also roughly U-shaped when viewed from below and is formed to protrude downward from the other parts. By forming these edges 61a1 and 62a2, it becomes easier for the worker to see the presence of the gripping parts 61a and 62a, and it also becomes easier to grip the center of the gripping parts 61a and 62a (the part enclosed by the edges 61a1 and 62a2), thus improving the worker's ability to attach and detach the parts. Furthermore, in order to obtain a similar effect, the gripping parts 61a and 62a may be distinguished from other parts (upper surface 60a and lower surface 60b) and colored or have decals attached.

[0037] Referring to Figure 9(A), in this embodiment, the edges 61a1 and 62a2 are formed to protrude upward (+Z direction) above the upper surface 60a of the exterior-mounted frame 60 (exterior), and to protrude downward (-Z direction) below the lower surface 60b of the exterior-mounted frame 60. In contrast, as shown in Figure 9(B), the edges 61a1 and 62a2 can also be formed so that they do not protrude above the upper surface 60a (+Z direction) on the upper surface 60a of the exterior-mounted frame 60 (exterior), and do not protrude below the lower surface 60b (-Z direction) on the lower surface 60b of the exterior-mounted frame 60. When formed in this way, the edges 61a1 and 62a2 do not protrude from the exterior-mounted frame 60 in the Z direction, so the size of the fixing device 20 in the Z direction can be reduced.

[0038] Referring to Figure 7, the fixing device 20 (attachment / detachment unit) in this embodiment is configured such that the longitudinal length M2 of the gripping portion 62a formed on the lower surface 60b of the exterior-mounted frame 60 (exterior) is longer than the longitudinal length M1 of the gripping portion 61a formed on the upper surface 60a of the exterior-mounted frame 60 (M1 <M2)。 Furthermore, the length N2 in the short direction of the gripping portion 62a formed on the lower surface 60b of the exterior-mounted frame 60 (exterior) is configured to be longer than the length N1 in the short direction of the gripping portion 61a formed on the upper surface 60a of the exterior-mounted frame 60 (N1 <N2)。 This is related to what was explained earlier using Figure 8, because the upper gripping portion 61a only needs to be large enough for the worker's thumb to rest on, while the lower gripping portion 62a needs to be large enough for the worker's four fingers other than the thumb to support most of the load of the fixing device 20.

[0039] In this embodiment, the thickness of the gripping portion 61a formed on the upper surface 60a of the exterior-mounted frame 60 (exterior) can also be configured to be thicker than the thickness of the gripping portion 62a formed on the lower surface 60b of the exterior-mounted frame 60. Furthermore, the thermal conductivity of the gripping portion 61a formed on the upper surface 60a of the outer casing / frame 60 (outer casing) can be configured to be lower than that of the gripping portion 62a formed on the lower surface 60b of the outer casing / frame 60. This configuration can be achieved by using different resin materials for the fixing-side transport guide member 61 (gripping portion 61a) and the pressurizing-side transport guide member 62 (gripping portion 62a). Furthermore, with this configuration, the fixing belt 21, which is directly heated by the heat source (planar heater 24), is close by, and the fixing-side transport guide member 61 (gripping portion 61a), which tends to become hotter than the pressurized-side transport guide member 62 (gripping portion 62a), is less likely to feel the heat when the worker touches it.

[0040] Referring to Figure 1, in this embodiment, the image forming apparatus 100 is provided with a fan 120 above the fixing device 20 as an airflow generating means for creating airflow. The image forming apparatus 100 has an air intake port on its front (+Y direction) above the fuser 20, and an exhaust port on its rear (-Y direction) above the fuser 20, with a fan 120 installed in the exhaust port (or air intake port). With this configuration, an airflow is formed above the fuser 20, where air taken in from outside the image forming apparatus 100 through the air intake port is discharged to the outside through the exhaust port. This airflow then discharges the hot air that has moved above the fuser 20 to the outside of the image forming apparatus 100, reducing the temperature of the fuser 20. As a result, it becomes easier to remove the fuser 20 from the image forming apparatus body 100 immediately after use.

[0041] <Variation> As shown in Figure 10, the fixing device 20 in the modified example differs from that shown in Figure 7 in that the gripping portions 61a and 62a are formed at approximately the center position in the longitudinal direction (±Y direction). The fixing device 20 configured in this way has a smaller overall size (especially in the ±Y direction) compared to the one shown in Figure 7, and is designed to be held in one hand by the operator while performing attachment and detachment operations. As a result, the worker will be able to attach and detach the fixing device 20 by holding the central gripping parts 61a and 62a in a balanced manner with one hand.

[0042] As described above, the fixing device 20 in this embodiment is a detachable unit that is detachably installed on the image forming apparatus 100 (apparatus body), and is provided with an exterior-also serving frame 60 (exterior) made of a metal material. Furthermore, gripping portions 61a and 62a made of a material with lower thermal conductivity than the exterior-also serving frame 60 are formed so as to be exposed on a part of the outer surface of the exterior-also serving frame 60. This makes it possible to easily attach and detach the fixing device 20 to the main body 100 of the image forming apparatus without increasing its size or cost.

[0043] In this embodiment, the present invention was applied to a fixing device 20 that uses a fixing belt 21 as the fixing rotating body, a pressure roller 31 as the pressure rotating body, and a planar heater 24 as the heat source. However, the fixing device to which the present invention is applied is not limited to this. For example, the present invention can also be applied to fixing devices that use a heater or electromagnetic induction coil as the heat source, fixing devices that use fixing rollers or fixing belts (stretched between multiple roller members) as the fixing rotating body, and fixing devices that use a pressure belt as the pressure rotating body. Furthermore, although the present invention was applied to the fixing device 20 as a detachable unit in this embodiment, the detachable unit to which the present invention is applied is not limited to this, and the present invention can naturally be applied to other detachable units such as the process cartridge 6 and the exposure device 7. Furthermore, in this embodiment, the present invention was applied to a detachable unit (fixing device 20) that is detachably installed on the image forming apparatus body 100, which is the main body of the apparatus. However, the main body of the apparatus to which the detachable unit to which the present invention is applied is not limited to this, and the present invention can be applied to various devices (equipment). Furthermore, the same effects as those of this embodiment can be obtained in these cases as well.

[0044] It is clear that the present invention is not limited to this embodiment, and that this embodiment can be modified as appropriate within the scope of the technical concept of the present invention, in addition to what is suggested here. Furthermore, the number, position, shape, etc. of the constituent members are not limited to this embodiment, and can be set to a number, position, shape, etc. that is suitable for carrying out the present invention.

[0045] In this specification, the term "sheet" is defined to include not only paper but also all sheet-like recording media such as coated paper, label paper, OHP sheets, and film sheets that are to be transported. [Explanation of Symbols]

[0046] 20 Fixing device (detachable unit), 21 Fixing belt (fixing rotating body), 23 Holder (holding member), 24-sided heater (heat source), 31 Pressure roller (pressure rotating body), 60. Frame that doubles as an exterior (exterior, housing), 60a top, 60b bottom, 61 Fixing side transport guide member, 61a gripping part, 61a1 Edge, 61a2 Rib, 62 Pressurized side transport guide member, 62a grip part, 62a1 Edge, 62a2 Rib, 90, 91 screws, 100 Image forming apparatus (image forming apparatus main unit, apparatus main unit), 110 Opening and closing cover, 120 Fan (means of generating airflow), P-sheet (recording medium).

[0047] Furthermore, the embodiments of the present invention can also be, for example, combinations of appendices 1 to 18 as follows. (Note 1) A detachable unit that is detachably installed on the main body of the device, Exterior made of metal material, A gripping portion made of a material with lower thermal conductivity than the exterior, and formed to be exposed to a part of the outer surface of the exterior, A detachable unit is provided. (Note 2) The gripping portion is made of a resin material. The aforementioned exterior also functions as the housing for the detachable unit. The detachable unit according to Appendix 1, characterized by being equipped with a heat source. (Note 3) The detachable unit is formed in a substantially rectangular shape and is attached to and detached from the main body of the device with the shorter side as the attachment / detachment direction. The attachment / detachment unit according to Appendix 1 or Appendix 2, characterized in that the gripping portion is formed on the upper and lower surfaces of the exterior, respectively, on the downstream side in the mounting direction of the exterior. (Note 4) The attachment / detachment unit according to Appendix 3, characterized in that the gripping portion is formed by dividing it into two parts at approximately equal distances from approximately the center position in the longitudinal direction. (Note 5) The attachment / detachment unit according to Appendix 3, characterized in that the gripping portion is formed at approximately the center position in the longitudinal direction. (Note 6) The attachment / detachment unit according to any one of the appendices 3 to 5, characterized in that the gripping portion has multiple ribs extending in the longitudinal direction, spaced apart in the short direction. (Note 7) The attachment / detachment unit according to any one of the appendices 3 to 6, characterized in that the gripping portion has an edge that protrudes upward on the upper surface of the exterior and protrudes downward on the lower surface of the exterior, except on the downstream side in the mounting direction. (Note 8) The attachment / detachment unit according to Appendix 7, characterized in that the edge portion is formed to protrude above the upper surface of the exterior and to protrude below the lower surface of the exterior. (Note 9) The attachment / detachment unit according to Appendix 7, characterized in that the edge portion is formed so as not to protrude above the upper surface of the outer casing, and so as not to protrude below the lower surface of the outer casing. (Note 10) The attachment / detachment unit according to any one of the appendices 3 to 9, characterized in that the longitudinal length of the gripping portion formed on the lower surface of the exterior is longer than the longitudinal length of the gripping portion formed on the upper surface of the exterior. (Note 11) The attachment / detachment unit according to any one of the appendices 3 to 10, characterized in that the length in the short direction of the gripping portion formed on the lower surface of the exterior is longer than the length in the short direction of the gripping portion formed on the upper surface of the exterior. (Note 12) The attachment / detachment unit according to any one of Appendix 3 to Appendix 11, characterized in that the thickness of the gripping portion formed on the upper surface of the exterior is greater than the thickness of the gripping portion formed on the lower surface of the exterior. (Note 13) The attachment / detachment unit according to any one of Appendix 3 to Appendix 12, characterized in that the thermal conductivity of the gripping portion formed on the upper surface of the exterior is lower than that of the gripping portion formed on the lower surface of the exterior. (Note 14) A fixing device as a detachable unit according to any one of the appendices 1 to 13, which is detachably installed on the main body of the image forming apparatus, which is the main body of the apparatus, A fixing rotating body heated by a heat source, A pressurizing rotating body that forms a nip section on which the sheet is conveyed by pressing it against the aforementioned fixing rotating body, A fixing device characterized by being equipped with the following features. (Note 15) A fixing-side transport guide member is positioned on the side of the fixing rotating body, inside the outer casing, and guides the sheet fed out from the nip portion. A pressurized side conveying guide member is positioned on the side of the pressurized rotating body and inside the outer casing, and guides the sheet delivered from the nip portion. Equipped with, The fixing device according to Appendix 14, characterized in that the gripping portion is integrally formed on the fixing-side transport guide member and the pressurizing-side transport guide member, respectively, so as to be exposed on the outer surface of the exterior. (Note 16) The aforementioned anchoring-side transport guide member is fastened with screws from the upper surface of the exterior, The fixing device according to Appendix 14, characterized in that the front pressurized attachment side transport guide member is fastened with screws from the lower surface of the outer casing. (Note 17) An image forming apparatus characterized by being equipped with a fixing device described in any of Appendix 14 to Appendix 16 on the main body of the image forming apparatus. (Note 18) The image forming apparatus according to Appendix 17, characterized in that it is provided with an airflow generating means for generating airflow above the fixing device. [Prior art documents] [Patent Documents]

[0048] [Patent Document 1] Patent No. 6780387 [Patent Document 2] Japanese Patent Publication No. 2023-165600

Claims

1. A detachable unit that is detachably installed on the main body of the device, Exterior made of metal material, A gripping portion made of a material with lower thermal conductivity than the exterior, and formed to be exposed to a part of the outer surface of the exterior, A detachable unit is provided.

2. The gripping portion is made of a resin material. The aforementioned exterior also functions as the housing for the detachable unit. The detachable unit according to claim 1, characterized by being equipped with a heat source.

3. The detachable unit is formed in a substantially rectangular shape and is attached to and detached from the main body of the device with the shorter side as the attachment / detachment direction. The attachment / detachment unit according to claim 1 or 2, characterized in that the gripping portion is formed on the upper and lower surfaces of the exterior, respectively, on the downstream side in the mounting direction of the exterior.

4. The attachment / detachment unit according to claim 3, characterized in that the gripping portion is formed by dividing it into two parts at substantially equal distances from a substantially central position in the longitudinal direction.

5. The attachment / detachment unit according to claim 3, characterized in that the gripping portion is formed at approximately the center position in the longitudinal direction.

6. The attachment / detachment unit according to claim 3, characterized in that the gripping portion has a plurality of ribs extending in the longitudinal direction, spaced apart in the short direction.

7. The attachment / detachment unit according to claim 3, characterized in that the gripping portion has an edge portion that protrudes upward on the upper surface of the exterior and protrudes downward on the lower surface of the exterior, except on the portion on the downstream side in the mounting direction.

8. The attachment / detachment unit according to claim 7, characterized in that the edge portion is formed to protrude above the upper surface of the exterior and to protrude below the lower surface of the exterior.

9. The attachment / detachment unit according to claim 7, characterized in that the edge portion is formed so as not to protrude above the upper surface of the outer casing, and so as not to protrude below the lower surface of the outer casing.

10. The attachment / detachment unit according to claim 3, characterized in that the longitudinal length of the gripping portion formed on the lower surface of the exterior is longer than the longitudinal length of the gripping portion formed on the upper surface of the exterior.

11. The attachment / detachment unit according to claim 3, characterized in that the length in the short direction of the gripping portion formed on the lower surface of the exterior is longer than the length in the short direction of the gripping portion formed on the upper surface of the exterior.

12. The attachment / detachment unit according to claim 3, characterized in that the thickness of the gripping portion formed on the upper surface of the exterior is greater than the thickness of the gripping portion formed on the lower surface of the exterior.

13. The attachment / detachment unit according to claim 3, characterized in that the thermal conductivity of the gripping portion formed on the upper surface of the exterior is lower than the thermal conductivity of the gripping portion formed on the lower surface of the exterior.

14. A fixing device as a detachable unit according to claim 1 or 2, which is detachably installed on the main body of an image forming apparatus as the main body of the apparatus, A fixing rotating body heated by a heat source, A pressurizing rotating body that forms a nip section on which the sheet is conveyed by pressing it against the aforementioned fixing rotating body, A fixing device characterized by being equipped with the following features.

15. A fixing-side transport guide member is positioned on the side of the fixing rotating body, inside the outer casing, and guides the sheet fed out from the nip portion. A pressurized side conveying guide member is positioned on the side of the pressurized rotating body and inside the outer casing, and guides the sheet delivered from the nip portion. Equipped with, The fixing device according to claim 14, characterized in that the gripping portion is integrally formed on the fixing-side transport guide member and the pressurizing-side transport guide member, respectively, so as to be exposed on the outer surface of the exterior.

16. The aforementioned anchoring-side transport guide member is fastened with screws from the upper surface of the exterior, The fixing device according to claim 14, characterized in that the front pressurized attachment side transport guide member is fastened with screws from the lower surface of the outer casing.

17. An image forming apparatus characterized in that the fixing device described in claim 14 is provided in the main body of the image forming apparatus.

18. The image forming apparatus according to claim 17, characterized in that it is provided with an airflow generating means for generating airflow above the fixing device.

Images