fixing unit

Abstract

A fixing unit includes a loop-shaped belt, a heater, a pressure roller including a roller portion formed of rubber, and a frame formed of resin. The frame includes a base surface facing an outer surface of the roller portion. The base surface includes a first rib and a second rib. The first rib is formed with a first shape. The second rib is formed with a second shape. The first shape is a first through-hole that penetrates the first rib in a longitudinal direction or a first groove portion formed in a part of a circular-arc shape of the first rib. The second shape is a second through-hole that penetrates the second rib in the longitudinal direction or a second groove portion formed in a part of the circular-arc shape of the second rib.

Description

Technical Field

[0001] This disclosure relates to a fixing unit for mounting on an imaging device of an electrophotographic system. Background Technology

[0002] The fixing unit described in Japanese Patent Application Publication No. 2024-31208 includes a heating unit and a pressure roller. The heating unit is equipped with a heater that heats the inner surface of a belt. The pressure roller forms a clamping portion by clamping the belt with the heater, thereby fixing the toner on the recording material. Summary of the Invention

[0003] One aspect of this disclosure provides a fixing unit comprising: an annular belt; a heater configured to heat the inner surface of the belt; a pressure roller including a roller portion made of rubber and configured to form a clamping portion by clamping the belt with the heater, such that recording material is conveyed through the clamping portion in a conveying direction; and a frame formed of resin, configured to rotatably support the pressure roller and arranged to face the roller portion in the longitudinal direction of the pressure roller, wherein the frame includes a base surface facing an outer surface of the roller portion in the longitudinal direction, wherein the base surface includes portions along the conveying direction and longitudinal direction. The first rib and the second rib extend in the intersecting directions of the two ribs, wherein, when viewed in the longitudinal direction, the top portions of the first rib and the top portions of the second rib both have an arc shape along the outer surface of the roller portion, wherein the first rib and the second rib are aligned in the longitudinal direction, wherein the first rib has a first shape, wherein the second rib has a second shape, wherein the first shape is a first through hole extending through the first rib in the longitudinal direction or a first groove portion formed in a part of the arc shape of the first rib, and wherein the second shape is a second through hole extending through the second rib in the longitudinal direction or a second groove portion formed in a part of the arc shape of the second rib.

[0004] Another aspect of this disclosure provides a fixing unit comprising: an annular belt; a heater configured to heat an inner surface of the belt; a pressure roller including a roller portion made of rubber and configured to form a clamping portion by clamping the belt with the heater, such that recording material is conveyed through the clamping portion in a conveying direction; and a frame formed of resin, configured to rotatably support the pressure roller and arranged to face the roller portion in a longitudinal direction of the pressure roller, wherein the frame includes a base surface facing an outer surface of the roller portion in the longitudinal direction, wherein the base surface includes a first rib and a second rib extending in an intersecting direction intersecting both the conveying direction and the longitudinal direction, wherein, when viewed in the longitudinal direction, the tip portion of the first rib and the second rib are... The top portion of the second rib has an arc shape along the outer surface of the roller portion. The first rib and the second rib are aligned in the longitudinal direction. The base surface includes a first intersecting rib with a first shape and a second intersecting rib with a second shape. The first intersecting rib and the second intersecting rib are disposed between the first rib and the second rib in the longitudinal direction and extend in the longitudinal direction and the intersection direction. The first intersecting rib and the second intersecting rib are disposed at different positions in the conveying direction. The first shape is a first through hole through the first intersecting rib in the conveying direction or a groove portion formed in the top portion of the first intersecting rib in the intersection direction. The second shape is a second through hole through the second intersecting rib in the conveying direction or a groove portion formed in the top portion of the second intersecting rib in the intersection direction.

[0005] Another aspect of this disclosure provides a fixing unit comprising: an annular belt; a heater configured to heat the inner surface of the belt; a pressure roller including a roller portion formed of rubber and configured to form a clamping portion by clamping the belt with the heater, such that recording material is conveyed through the clamping portion in a conveying direction; a frame formed of resin, configured to rotatably support the pressure roller and arranged to face the roller portion in the longitudinal direction of the pressure roller; and a temperature detection unit for detecting the temperature of the pressure roller. The frame includes a base surface facing the roller portion in an intersecting direction that intersects both the conveying direction and the longitudinal direction. The base surface includes a first rib and a second rib extending along the intersecting direction. When viewed in the longitudinal direction, the tip portions of the first rib and the second rib both have an arc shape along the outer surface of the roller portion. The first rib and the second rib are aligned in the longitudinal direction. The frame is formed with a through hole extending from the base surface to the outside of the frame and located between the first rib and the second rib. A temperature detection unit is configured to pass through the through hole and face the pressure roller.

[0006] The features of this disclosure will become apparent from the following description of embodiments with reference to the accompanying drawings. The following description of the embodiments is by way of example. Attached Figure Description

[0007] Figure 1 A cross-sectional view along the short direction of the lower frame and pressure roller of the fixing unit is shown according to Example 1.

[0008] Figure 2 This is a cross-sectional view showing an imaging device according to an embodiment.

[0009] Figure 3 This is a cross-sectional view showing the fixing unit according to an embodiment.

[0010] Figure 4 This is a cross-sectional view showing the fixing unit according to an embodiment.

[0011] Figure 5 This is an exploded perspective view showing the fixing unit according to an embodiment.

[0012] Figure 6A This is a front view showing the fixing unit according to an embodiment.

[0013] Figures 6B to 6D This is a cross-sectional view showing the fixing unit according to an embodiment.

[0014] Figure 7A and Figure 7B This is a cross-sectional view showing the fixing unit according to an embodiment.

[0015] Figure 8 This is an exploded perspective view showing the fixing unit according to an embodiment.

[0016] Figure 9 A cross-sectional view is shown along the longitudinal direction of the lower frame and pressure roller in Example 1.

[0017] Figure 10A and Figure 10B This is a diagram showing the conveyor direction rib in Example 1.

[0018] Figures 10C to 10F This is a diagram showing the conveyor direction rib in the modified example.

[0019] Figure 11A A cross-sectional view is shown along the longitudinal direction of the lower frame and pressure roller in Example 2.

[0020] Figure 11B This is a diagram showing the through-hole of the longitudinal rib in the modified example.

[0021] Figure 12A This is a perspective view showing the lower frame in Example 3.

[0022] Figure 12B This is an enlarged view of a portion of the lower frame in Example 3.

[0023] Figure 13 This is a bottom view showing the lower frame in Example 4.

[0024] Figure 14 This is the front view of the lower frame in Example 1, which is a modification of Example 4.

[0025] Figure 15 This is the back view of the lower frame in Example 2, which is a modification of Example 4.

[0026] Figure 16 This is the front view of the lower frame in Example 3, which is a modification of Example 4.

[0027] Figure 17 This is a perspective view showing the lower frame in Example 5.

[0028] Figure 18 This is a schematic diagram showing a cross-section along the shorter direction of the lower frame and pressure roller in Example 5.

[0029] Figure 19 This is a schematic diagram showing a cross-section of the lower frame and pressure roller in the short direction of a modified example of Example 5.

[0030] Figure 20A and Figure 20B This is a diagram illustrating an example of the thermistor arrangement in Example 5. Detailed Implementation

[0031] In the following description, embodiments according to the present disclosure will be described with reference to the accompanying drawings.

[0032] Figure 2 This is a cross-sectional view showing an imaging device 1, which includes a fixing unit 6 serving as a fixing unit according to one embodiment. In the following description, as... Figure 2 As shown, when the imaging device 1 is mounted on a horizontal plane, the vertical direction is called the Z direction. The direction intersecting the Z direction is called the Y direction. The Y direction corresponds to the rotation axis direction of the pressure roller 62 described below. The direction intersecting both the Z and Y directions is called the X direction. The X direction corresponds to the direction parallel to the direction in which the heating unit 61 conveys the recording material located at the clamping portion, as described below. The X and Y directions are preferably horizontal directions. Furthermore, the X, Y, and Z directions are preferably orthogonal to each other.

[0033] Furthermore, if necessary, the arrows X, Y, and Z shown in the figures are referred to as +X, +Y, and +Z directions, respectively, and their opposite directions are referred to as -X, -Y, and -Z directions, respectively. In the following description, the conveying direction of the sheet S used as recording material at the clamping portion np1 described below is referred to as the sheet conveying direction D1. Figure 2 In this embodiment, the sheet conveying direction D1 is along the +X direction. Furthermore, the rotation axis direction of the pressure roller 62 is sometimes referred to as the axial direction, the longitudinal direction of the fixing unit 6, or simply the "longitudinal direction." In this axial direction, the direction from one end of the pressure roller 62 to the other end is called the first axial direction (+Y direction). In this axial direction, the direction opposite to the first axial direction is called the second axial direction (-Y direction). The Y direction is also the longitudinal direction of the fixing unit 6. Furthermore, the Y direction is the longitudinal direction or generatrix direction of the belt 614.

[0034] Imaging equipment

[0035] use Figure 2 The configuration of imaging device 1 will be described. Imaging device 1 includes a device body 2, a processing cartridge 10, and a fixing unit 6. The processing cartridge 10 is detachably attached to the device body 2. The fixing unit 6 is detachably attached to the device body 2. Alternatively, the fixing unit 6 is mounted relative to the device body 2. It should be noted that the fixing unit 6 can also be attached in a non-detachable manner.

[0036] The main body 2 includes a feed tray 3, a sheet feed unit 4, a conveyor path P, a transfer roller 51, a sheet discharge unit 7, a discharge tray 8, a laser scanner 9, and an opening / closing door 21. The processing cartridge 10 includes a photosensitive drum 11 and a developing roller 12 serving as a developer carrier. Furthermore, the processing cartridge 10 stores developer internally. The opening / closing door 21 is pivotally supported about a central pivot 21a and is configured to move between a closed position (closing the opening portion 2a) and an open position (opening the opening portion 2a). When the opening / closing door 21 is in the open position (where the opening portion 2a is open), the processing cartridge 10 can be attached to and detached from the main body 2 via the opening portion 2a.

[0037] The sheet feeding unit 4 includes a feed roller 41, a separation roller 42, a separation pad 42a, and a transfer roller pair 43. Based on the printing start signal, the sheet S stored in the feed tray 3 is sent by the sheet feeding unit 4 to the transfer path P, and is transferred to the transfer roller 51 via the registration roller pair 44.

[0038] When the sheet S is conveyed to the predetermined position, an imaging start signal is emitted, and the imaging process begins. The photosensitive drum 11, rotatably driven by a drive source (motor, not shown), is uniformly charged to a predetermined potential via a charging device (not shown). The surface of the charged photosensitive drum 11 is exposed based on image information by a laser scanner 9, forming an electrostatic latent image where the charge has been removed from the exposed area. Toner in the processing cartridge 10, carried by the developing roller 12, is supplied to the photosensitive drum 11 according to the electrostatic latent image; thereby, the latent image is developed. Thus, the latent image is visualized as a toner image on the photosensitive drum 11.

[0039] The transfer roller 51 is arranged to face the photosensitive drum 11 contained within the processing cartridge 10. When the sheet S, conveyed by the registration roller pair 44, passes through the clamping portion between the photosensitive drum 11 and the transfer roller 51, voltage from the device body 2 is applied to the transfer roller 51, and the toner image on the photosensitive drum 11 is transferred onto the sheet S as an unfixed image. The sheet S with the toner image transferred onto it is then conveyed to the fixing unit 6, which is equipped with a heating unit 61 and a pressure roller 62. The fixing unit 6 is a unit that fixes the toner (developer) onto the recording material. As the sheet S passes through the clamping portion of the heating unit 61 and the pressure roller 62, the unfixed image transferred onto the sheet S is heated and pressurized, and fixed onto the surface of the sheet S. The sheet S with the toner image fixed onto it is discharged to the discharge tray 8 via the sheet discharge unit 7.

[0040] Fixing unit

[0041] Next, the configuration of fixing unit 6 will be described. Figure 3 This is a plan view showing the fixing unit 6. As detailed below, the fixing unit 6 includes an annular belt 614 and a heater 611 for heating the inner surface of the annular belt 614. Furthermore, the fixing unit 6 includes a pressure roller 62, which includes a rubber roller portion 62b. This rubber roller portion forms a clamping portion np1 by clamping the belt 614 with the heater 611, such that recording material is conveyed through the clamping portion np1 in the conveying direction (sheet conveying direction D1). Additionally, the fixing unit 6 includes a resin frame (lower frame 63) that rotatably supports the pressure roller 62 and faces the roller portion 62b in the longitudinal direction of the pressure roller 62.

[0042] like Figure 3 As shown, the heating unit 61 includes a heater 611, a bracket 612, a support member 613, and a belt 614. The heater 611 is disposed on the inner surface side of the belt 614 and heats the belt 614. The heater 611 extends along the longitudinal direction (Y direction) of the belt 614 and has a flat plate shape. The heater 611 includes a first surface 611a and a second surface 611b located on the side opposite to the first surface 611a, and the first surface 611a is supported by the bracket 612.

[0043] The support 612 is formed of a heat-resistant resin (such as polyphenylene sulfide (PPS) or a liquid crystal polymer) and includes a guide surface 612a and a support wall 612b. The guide surface 612a guides the belt 614 by contacting the inner surface 614a of the belt 614, and the support wall 612b includes a support surface 612b1 supporting the heater 611. The support surface 612b1 of the support wall 612b contacts the first surface 611a of the heater 611. The support member 613 is a component that supports the support 612 and is formed by bending a plate-like material (such as a steel plate with a thickness of 1.6 mm) having a higher stiffness than the support 612 into a generally U-shaped configuration.

[0044] The belt 614 is a heating element (heating rotating element) for heating an image on a recording material. In this embodiment, the belt 614 is a heat-resistant and flexible annular belt, and is constructed, for example, of a metal sleeve (such as stainless steel) coated with a fluororesin or a laminate of polyimide resin, silicone rubber, fluororesin, etc. The belt 614 may also be referred to as a rotatable tubular membrane. A heater 611, a bracket 612, and a support member 613 are arranged inside the belt 614, and the belt 614 is configured to rotate around these components. The inner surface 614a of the belt 614 contacts the second surface 611b of the heater 611.

[0045] The pressure roller 62 includes a metal shaft 62a and a roller portion 62b (outer peripheral portion) formed of an elastic material covering the shaft 62a, and is pressed against the heater 611 via a belt 614. The pressure roller 62 forms a clamping portion np1 for clamping and heating the sheet S by clamping itself between itself and the belt 614 and the heater 611. In other words, it can be said that the pressure roller 62, together with the heater 611 via the belt 614, forms the clamping portion np1. That is, the pressure roller 62 is a rotating member used to engage with the heater 611 to heat and pressurize the sheet S at the clamping portion np1. The clamping portion np1 is the contact portion where the belt 614 and the pressure roller 62 contact each other.

[0046] The pressure roller 62 is configured to rotate when a driving force from a drive source included in the imaging device 1 is transmitted. As the pressure roller 62 rotates, the belt 614 also rotates synchronously with the pressure roller 62. The sheet S on which the toner image has been transferred is conveyed between the pressure roller 62 and the heated belt 614, thereby heat-fixing the toner image.

[0047] Next, use Figure 4 The frame configuration of fixing unit 6 will be described. Figure 4This is a plan view showing the fixing unit 6. The fixing unit 6 includes an upper frame 64 and a lower frame 63. The upper frame 64 and the lower frame 63 form the main frame of the fixing unit 6. The lower frame 63 and the upper frame 64 can also be referred to as the first frame and the second frame, respectively.

[0048] It is important to note that Figures 4 to 8 The configuration of the lower frame 63 shown is an example, and the detailed configuration of the lower frame 63 will be described in the example described below.

[0049] The lower frame 63 is a frame that supports the heating unit 61 and the pressure roller 62. The upper frame 64 is located on top of the lower frame 63 and covers the heating unit 61. The lower frame 63 and the upper frame 64 are resin components formed from non-conductive molded components (resin components).

[0050] The upper frame 64 includes an upper guide surface 64a disposed downstream of the heating unit 61 in the sheet conveying direction D1. The upper guide surface 64a guides the upper surface of the sheet S conveyed along the sheet conveying direction D1. The lower frame 63 includes a lower guide surface 63a disposed downstream of the heating unit 61 in the sheet conveying direction D1. The lower guide surface 63a guides the lower surface of the sheet S conveyed along the sheet conveying direction D1.

[0051] Next, use Figure 5 The configuration of the lower frame 63 supporting the pressure roller 62 will be described. Figure 5 This is an exploded perspective view showing the fixing unit 6. The lower frame 63 includes guide rails 63b at each end portion in the first and second axial directions. The guide rails 63b extend vertically and support the bracket 612 in a manner allowing vertical movement. The two guide rails 63b are each arranged to face each other in the axial direction. The guide rails 63b engage with recessed portions 617a1 and 617b1 respectively provided in the transmission members 617a and 617b.

[0052] The fixing unit 6 includes support members 62c and 62d. The end portions of shaft 62a in the first axial direction and the second axial direction are supported by support members 62c and 62d, respectively. Support member 62c is positioned by fitting into a recessed portion 63d1 provided in the lower frame 63. Similarly, support member 62d is positioned by fitting into a recessed portion 63d2 provided in the lower frame 63. It should be noted that support member 62c is conductive. It should be noted that in this configuration, protrusions 62c1 and 62d1 are provided in support members 62c and 62d, and recesses 63d1 and 63d2 are provided in the lower frame 63; however, the protrusion-recession relationship can be reversed. Furthermore, the fixing portion that secures support members 62c and 62d to the lower frame 63 is not limited to the protrusion-recession configuration.

[0053] pressurization mechanism

[0054] Next, the pressurization mechanism of the fixing unit 6 will be described. Figure 6A This is a plan view showing the fixing unit 6. Figures 6B to 6D Each is along Figure 6A The short-section view of the fixing unit 6. The short section (short section) refers to the section of the fixing unit 6 taken along an imaginary plane perpendicular to the longitudinal direction (Y direction) of the fixing unit 6. Furthermore, the section (longitudinal section) along the longitudinal direction of the fixing unit 6 as described below refers to the section of the fixing unit 6 taken along an imaginary plane parallel to the longitudinal direction (Y direction) of the fixing unit 6 (in particular, the plane containing the rotation axis of the pressure roller 62).

[0055] like Figures 6A to 6D As shown, the fixing unit 6 includes a pressure mechanism 65 for pressurizing the clamping portion np1. In this embodiment, the pressure mechanism 65 pushes the heating unit 61 relative to the pressure roller 62. The pressure mechanism 65 is provided at each end portion of the lower frame 63 in the first axial direction and the second axial direction. In other words, the pressure mechanism 65 can also be said to be supported by the lower frame 63. It should be noted that the configurations of the pressure mechanisms 65 provided on both sides of the corresponding end portions in the first axial direction and the second axial direction of the lower frame 63 are substantially the same. Therefore, the description of the pressure mechanism 65 provided on the first axial direction side also applies to the pressure mechanism 65 provided on the second axial direction side; therefore, repeated descriptions will be omitted.

[0056] The pressurization mechanism 65 includes a transmission member 651, a pressurization arm 652, and a pressurization spring 653. The pressurization arm 652 is supported by a lower frame 63. More specifically, the pressurization arm 652 is supported by a support portion 64d of the lower frame 63 and is pivotally supported about a central axis X1 of the support portion 64d. The support portion 64d is a generally cylindrical protrusion.

[0057] The pressure arm 652 applies pressure to the transmission member 651 from above, causing the transmission member 651 to move downwards. This, in turn, applies pressure to the support member 613 in the downward direction. The transmission member 651 applies pressure to the support member 613, causing it to move downwards. As the support member 613 moves downwards, the heating unit 61, including the support member 613, is pushed towards the pressure roller 62. The pressure spring 653, a conductive tension helical spring, pushes the pressure arm 652, pressing the heating unit 61 against the pressure roller 62. The end portions 653a and 653b of the pressure spring 653 engage with portions 63e1 of the lower frame 63 and 652a of the pressure arm 652. When the pressure spring 653 pushes the pressure arm 652, the pressure arm 652 causes the transmission member 651 to move downwards. In other words, the pressure arm 652 pushes the heating unit 61 against the pressure roller 62.

[0058] Pressure relief mechanism

[0059] Next, use Figure 7A , Figure 7B and Figure 8 The configuration of the pressure release mechanism set in the fixing unit 6 will be described. Figure 7A and Figure 7B This is a cross-sectional view of fixing unit 6 along the shorter direction. Figure 7A The pressurized state is shown, in which the pressure release mechanism 67 allows pressurization at the clamping portion np1. Figure 7B The pressure release state is shown, in which the pressure release mechanism 67 releases the pressure at the clamping portion np1. Figure 8 An exploded perspective view of the upper frame 64, the lower frame 63, and the camshaft 671 is shown, with some components such as the heating unit 61 and the pressure roller 62 omitted.

[0060] The pressure relief mechanism 67 is a mechanism for changing the clamping pressure between the heating unit 61 and the pressure roller 62 at the clamping part np1. The pressure relief mechanism 67 includes a camshaft 671 and a cam 672.

[0061] like Figure 7A and Figure 7B As shown, the camshaft 671 can pivot about a central axis X2. The camshaft 671 extends axially and is made of conductive metal. Figure 8 As shown, cam 672 is fixed (supported) to each of the corresponding end portions in the first and second axial directions of camshaft 671. Cam 672 is supported in a manner that allows it to rotate together with camshaft 671. Cam 672 is disposed on each side of the corresponding end portions in the first and second axial directions of lower frame 63. The configurations of cam 672 disposed at the corresponding end portions in the first and second axial directions of lower frame 63 are substantially the same.

[0062] The cam 672 applies pressure to the pressure arm 652 against the pushing force of the pressure spring 653. That is, by rotating the cam 672, the pressure applied by the heating unit 61 to the pressure roller 62 by the pressure arm 652 is changed. The cam 672 can... Figure 7A The pressurization position shown is... Figure 7B It pivots between the pressure relief positions shown.

[0063] When the pressurization is released, the cam 672 rotates as the camshaft 671 rotates. As the cam 672 rotates, the pressure arm 652, which is in contact with the cam 672, moves away from the transmission member 651 in the opposite direction to the direction in which the support member 613 presses against the transmission member 651. This reduces the pressure applied by the heating unit 61 towards the pressure roller 62.

[0064] Next, use Figure 8 The support configuration of the camshaft 671 will be described below. The lower frame 63 includes a support wall 631 that rotatably supports the camshaft 671. The support wall 631 extends in a vertical direction (Z direction). The support wall 631 includes a hole 631h that pivotally supports the camshaft 671. The camshaft 671 passes through the hole 631h. In other words, the support wall 631 can also be referred to as the shaft support portion supporting the camshaft 671. It should be noted that the support wall 631 is provided on each side of the corresponding end portions in the first and second axial directions of the lower frame 63. Furthermore, substantially identical holes 631h are provided in the respective support walls 631.

[0065] The upper frame 64 includes a support wall 641 that pivotally supports a camshaft 671. The support wall 641 extends vertically. The support wall 641 includes a hole 641h that pivotally supports the camshaft 671. The camshaft 671 passes through the hole 641h. It should be noted that the support walls 641 are provided on each side of the corresponding end portions in the first and second axial directions of the lower frame 63. Furthermore, substantially identical holes 641h are provided in the respective support walls 641.

[0066] Example 1

[0067] The fixing unit 6 according to Example 1 will be described, which is an example of this embodiment. In this example, a configuration for reducing the effects of water vapor generated by the recording material in the fixing unit 6 is proposed, the configuration including a plurality of ribs extending along the sheet transport direction D1.

[0068] The effect of water vapor generated by the sheet

[0069] First, the effect of water vapor generated on the sheet S during its passage through the clamping portion np1 of the fixing unit 6 will be described. Specifically, in a high-temperature and high-humidity environment, the paper (used as the sheet S) placed on the feed tray 3 contains a large amount of moisture. When this moisture-containing paper passes through the clamping portion np1, water vapor is generated from the paper because the paper is also heated along with the toner image. When the generated water vapor causes condensation on the surface of the pressure roller 62, the frictional force with the sheet S decreases, and image distortion may occur due to the slippage of the sheet S. Furthermore, due to the localized change in frictional force caused by condensation, the conveying force applied to the sheet S by the pressure roller 62 can enter a state where the conveying force varies depending on the position in the longitudinal direction, and therefore, wrinkles can be formed in the sheet S.

[0070] Reinforcing ribs of the lower frame

[0071] Next, the shape and arrangement of the reinforcing ribs 80 set in the lower frame (frame) 63 in this example will be described.

[0072] Figure 9 This is a cross-sectional view showing the longitudinal section of the lower frame 63 on which the pressure roller 62 is mounted. (See attached image.) Figure 4 , Figure 5 and Figure 9 As shown, one or more reinforcing ribs 80 are provided on the lower frame 63.

[0073] The lower frame 63 includes a base surface 630d, a front surface 630a facing upstream in the sheet conveying direction D1, a bottom surface 630b facing downward, a rear surface 630c facing downstream in the sheet conveying direction D1, and a reinforcing rib 80.

[0074] The base surface 630d refers to the opposite surface (inner surface of the lower frame 63) of the front surface 630a, bottom surface 630b, and rear surface 630c, which are the surfaces facing the outside of the lower frame 63. The base surface 630d is positioned as the outer peripheral surface (outer surface) of the roller portion 62b of the pressure roller 62. For example... Figure 4 As shown, when viewed in the longitudinal direction, at least a portion of the pressure roller 62 is contained within the space surrounded by the base surface 630d.

[0075] A reinforcing rib 80 is provided on the base surface 630d and extends along the intersecting direction D2. In other words, the reinforcing rib 80 is formed to protrude from the base surface 630d toward the outer peripheral surface of the pressure roller 62. The intersecting direction D2 is the direction that intersects both the longitudinal direction (Y direction) of the pressure roller 62 and the sheet conveying direction D1. The intersecting direction D2 can be a direction that intersects perpendicularly to both the longitudinal direction (Y direction) of the pressure roller 62 and the sheet conveying direction D1.

[0076] The base surface 630d, front surface 630a, bottom surface 630b, and rear surface 630c constitute the main body 630 of the lower frame 63 extending in the longitudinal direction. The reinforcing rib 80 is supported by the main body 630. The reinforcing rib 80 and the main body 630 are integrally formed from resin material.

[0077] The lower frame 63 of this example includes one or more transport direction ribs 801 serving as reinforcing ribs 80. Figure 9 In the example shown, the lower frame 63 includes a plurality of transport direction ribs 801. In other words, the term "frame" in this example includes both a first rib and a second rib. An example of a first rib is one of the plurality of transport direction ribs 801 (e.g., Figure 9 (in the transmission direction rib 801-1), and an example of the second rib is another of a plurality of transmission direction ribs 801 (e.g., Figure 9 (Transmission direction rib 801-2 in the middle).

[0078] In this example, multiple conveying direction ribs 801 are arranged at substantially equal intervals along the longitudinal direction. It can be said that the multiple conveying direction ribs 801 include a first rib (conveying direction rib 801-1) and a second rib (conveying direction rib 801-2) aligned along the longitudinal direction.

[0079] One side of the end portion of the base surface 630d in the longitudinal direction is referred to as the first end portion 630d1, and the other side of the end portion is referred to as the second end portion 630d2. Figure 9 In the longitudinal direction, the first rib (transfer direction rib 801-1) is closer to the first end portion 630d1 than the second end portion 630d2, and the second rib (transfer direction rib 801-2) is closer to the second end portion 630d2 than the first end portion 630d1. In other words, the first rib and the second rib can be arranged opposite to each other, with the center of the base surface 630d in the longitudinal direction placed between them.

[0080] The lower frame 63 may include longitudinal ribs 803 extending in the longitudinal direction (Y direction). Figure 4 and Figure 5 In other words, the reinforcing rib 80 may include one or more conveying direction ribs 801 and one or more longitudinal direction ribs 803. It should be noted that in this example, the reinforcing rib 80 may consist only of the conveying direction ribs 801, without including the longitudinal direction ribs 803.

[0081] For example, the longitudinal rib 803 may be formed to extend at least along the entire length of the roller portion 62b of the pressure roller 62. The longitudinal rib 803 may be formed to extend over the entire area along the longitudinal direction of the base surface 630d. Furthermore, the longitudinal rib 803 is formed to intersect each of the plurality of conveying ribs 801.

[0082] The reinforcing ribs 80 enhance the rigidity of the lower frame 63 formed by the molded components. By increasing the rigidity with the help of the reinforcing ribs 80, the lower frame 63 can be prevented from deflecting due to heat generated from the heating unit 61 and the pressure roller 62 and the load applied via the pressurizing mechanism 65, and further, creep deformation due to prolonged operating time can be prevented.

[0083] Figure 1 The short-direction cross-section of the lower frame 63 on which the pressure roller 62 is mounted is shown, and an imaginary plane is shown along the rib 801 (801-1) passing through the conveying direction. Figure 9 The cross-sectional view of the section (DD section) taken from the middle section. Figure 10A This is a diagram showing a transmission direction rib 801-1 viewed along the longitudinal direction. Figure 10B This is a diagram showing another transmission direction rib 801-2 viewed along the longitudinal direction.

[0084] like Figure 1 As shown, in this example, the top portion 801a (ridge) of each conveying direction rib 801 is configured to be arc-shaped along the outer peripheral surface of the pressure roller 62.

[0085] The grooved portion of the reinforcing rib

[0086] A groove portion 801b is provided at at least one conveying direction rib in the conveying direction rib 801. The groove portion 801b is formed in a portion of the arcuate shape of the top portion 801a, and is a recessed portion (recessed portion) that is recessed toward the side away from the axis of rotation of the pressure roller 62 compared to the arcuate shape of the top portion 801a.

[0087] The groove portion 801b-1 (located in the conveying direction rib 801-1 (first rib)) Figure 10A ) is an example of the first groove portion, and the groove portion 801b-2 ( is provided in the conveying direction rib 801-2 (second rib) Figure 10B The first groove is an example of the second groove portion. Furthermore, the groove portion 801b-1 provided in the conveying direction rib 801-1 (first rib) is an example of the first shape, and the groove portion 801b-2 provided in the conveying direction rib 801-2 (second rib) is an example of the second shape.

[0088] The groove portion 801b establishes communication between the outer peripheral surface of the heating roller 62 and the base surface 630d of the lower frame 63, separated by the conveying direction rib 801. In other words, the groove portion 801b forms a path that allows air containing water vapor to move in the longitudinal direction.

[0089] It should be noted that the airflow flowing through the groove portion 801b in the longitudinal direction can be actively generated by the blower fan installed in the main body 2 of the equipment.

[0090] Function of the groove

[0091] If the small spaces separated by the conveying direction ribs 801 are configured to have high airtightness (minimum air transfer between adjacent spaces), air may stagnate within these small spaces. If air stagnates within these small spaces, water vapor generated by the sheet S during image fixing can accumulate and condense on the pressure rollers 62; therefore, the aforementioned adverse effects may occur.

[0092] As described in this example, by providing a groove portion 801b at the top portion 801a of the conveying direction rib 801, air stagnation is suppressed, and condensation on the pressure roller 62 can be prevented even in environments with high temperature and high humidity, such as when the sheet S contains a large amount of moisture. In other words, by the airflow flowing through the groove portion 801b in the longitudinal direction, water vapor generated from the sheet S during the image fixing process can be discharged from the area near the outer peripheral surface of the pressure roller 62.

[0093] Figure 10A and Figure 10B This diagram shows conveyor ribs 801-1 and 801-2 that are adjacent to each other in the longitudinal direction. In the longitudinal direction, conveyor ribs 801-1 and 801-2 (the first rib and the second rib) are arranged to face each other. Figure 9 ).

[0094] In the example shown, two recessed portions 801b-1 are formed in the first conveying direction rib 801-1. Figure 10A ), and two groove portions 801b-2 are formed in the second transmission direction rib 801-2 ( Figure 10B The number of groove portions 801b formed in the conveying direction ribs 801-1 and 801-2 can be different from each other.

[0095] exist Figure 10A and Figure 10BIn the example shown, when viewed along the longitudinal direction (Y direction), the groove portion 801b-1 formed in the first conveying direction rib 801-1 does not overlap with the groove portion 801b-2 formed in the second conveying direction rib 801-2. It should be noted that when viewed along the longitudinal direction (Y direction), Figure 10A The dashed line shown indicates the transparent projection position of the groove portion 801b-2 of the second conveying direction rib 801-2 onto the first conveying direction rib 801-1. As described above, by arranging the groove portion 801b between adjacent conveying direction ribs 801-1 and 801-2 such that they do not overlap, water vapor in the small space between adjacent conveying direction ribs 801 can be uniformly discharged.

[0096] On the other hand, with Figure 10A and Figure 10B In contrast, when viewed along the longitudinal direction (Y direction), the groove portion 801b can be arranged to overlap each other between the adjacent transport direction ribs 801-1 and 801-2. Figure 10C An example arrangement is shown where, when viewed along the longitudinal direction (Y direction), the groove portion 801b-1 of the first conveying direction rib 801-1 and the groove portion 801b-2 of the second conveying direction rib 801-2 overlap. In this case, the airflow in the longitudinal direction becomes smoother, thereby increasing the amount of air flowing through the space between the outer peripheral surface of the pressure roller 62 and the lower frame 63. Whether the groove portions 801b overlap or not when viewed along the longitudinal direction can be modified according to the specific configuration of the fixing unit 6 (especially the design of the airflow path), the position of the blower fan, etc.

[0097] In the direction of the airflow generated by the blower fan, the area of ​​the groove portion 801b on the downstream side of the conveying direction rib 801 can be configured to be larger than the area of ​​the groove portion 801b on the upstream side of the conveying direction rib 801. For example, in this case, compared to the case where the area of ​​the groove portion 801b on the downstream side of the conveying direction rib 801 is configured to be smaller, air can be discharged more smoothly, and water vapor retention can be prevented more effectively.

[0098] Modify Example

[0099] It should be noted that in this example, as an example of the first and second recessed portions, the recessed portion 801b has a rectangular shape and extends elongated relative to the direction perpendicular to the sheet conveying direction D1; however, the shape of the recessed portion 801b is not limited to this, and for example, when viewed along the longitudinal direction, it is acceptable to form the recessed portion 801b in a semi-circular shape. Furthermore, in Figure 1In one conveying direction rib 801, two recessed portions 801b are formed; however, a single recessed portion 801b may be formed, or three or more recessed portions 801b may be formed. In the case of multiple conveying direction ribs 801, the recessed portions 801b may be formed only in some of the conveying direction ribs 801.

[0100] In this example, as an example of a first shape and a second shape, the groove portion 801b (the first groove portion and the second groove portion) is configured to suppress the retention of water vapor; however, as Figure 10D and Figure 10E As shown, a through hole 801c can be formed in the conveying direction rib 801 instead of the recessed portion 801b. In other words, a hole penetrating in the longitudinal direction (Y direction) can be formed in the conveying direction rib 801 at a portion closer to the root side (base surface 630d side) than the top portion 801a. By forming the through hole 801c in the conveying direction rib 801, air transport between the small spaces separated by the conveying direction rib 801 is facilitated, and thus water vapor can be expelled.

[0101] Figure 10D This is a diagram showing an example of a first conveying direction rib 801-1 (first rib) forming a through hole 801c-1 (first through hole). Figure 10E This is a diagram showing an example of a second conveying direction rib 801-2 (second rib) forming a through hole 801c-2 (second through hole). As shown... Figure 10D As shown, when the through hole 801c-1 (first through hole, first shape) and the through hole 801c-2 (second through hole, second shape) overlap when viewed in the longitudinal direction, the airflow in the longitudinal direction becomes smoother.

[0102] On the other hand, such as Figure 10F As shown, when viewed along the longitudinal direction, through-hole 801c-1 (first through-hole, first shape) can be arranged so as not to overlap with through-hole 801c-2 (second through-hole, second shape). In this case, water vapor becomes easier to expel without leaking from the small space separated by the conveying direction ribs 801-1 and 801-2.

[0103] The shape of the through hole can be, for example, circular, elliptical, or quadrilateral (including parallelograms and rounded rectangles). The number of through holes can be one or more.

[0104] Example 2

[0105] Example 2 of this disclosure will now be described. The difference between this example and Example 1 is that the groove portion is provided in the longitudinal direction rib 803, which serves as an intersecting rib. Figure 4 and Figure 5In the following text, unless otherwise expressly stated, elements represented by the same reference characters as in Example 1 are considered to include substantially the same configuration and function as described in Example 1, and the following description will primarily discuss aspects that differ from Example 1.

[0106] Figure 11A This is a cross-sectional view showing a section along the longitudinal direction of the lower frame 63 on which the pressure roller 62 is mounted (a section taken along an imaginary plane passing through one of the longitudinal ribs 803). In the intersecting direction D2, the longitudinal ribs 803 protrude from the base surface 630d toward the outer peripheral surface of the pressure roller 62 (i.e., toward the upper side), and all extend in the longitudinal direction (Y direction). Furthermore, the top portion 803a (ridge) of the longitudinal rib 803 is formed linearly, for example, along the outer peripheral surface of the pressure roller 62.

[0107] The lower frame 63 may include a conveying direction rib 801 ( Figure 5 In other words, the reinforcing rib 80 may include one or more transport direction ribs 801 and one or more longitudinal direction ribs 803. It should be noted that in this example, the reinforcing rib 80 may consist only of longitudinal direction ribs 803, without including transport direction ribs 801.

[0108] The lower frame 63 in this example includes two longitudinal ribs 803 (see also [reference]). Figure 4 Each longitudinal rib 803 extends in the longitudinal direction and intersects with multiple conveying ribs 801. A first longitudinal rib 803-1 is an example of a first intersecting rib, extending in the longitudinal direction to connect conveying ribs 801-1 (first rib) and 801-2 (second rib). A second longitudinal rib 803-2 is an example of a second intersecting rib, extending in the longitudinal direction to connect conveying ribs 801-1 (first rib) and 801-2 (second rib), and is positioned facing the first intersecting rib in the sheet conveying direction D1. Furthermore, longitudinal ribs 803-1 and 803-2 include both the first and second intersecting ribs, thus serving as portions extending in the opposite longitudinal direction (Y direction) and the intersecting direction D2, and are positioned in the longitudinal direction between conveying ribs 801-1 (first rib) and 801-2 (second rib).

[0109] The end portion on one side of the base surface 630d is referred to as the first end portion 630d3, and the end portion on the other side is referred to as the second end portion 630d4. Figure 4In the sheet conveying direction, the first intersecting rib (longitudinal rib 803-1) is closer to the first end portion 630d3 than the second end portion 630d4. The second intersecting rib (longitudinal rib 803-2) is closer to the second end portion 630d4 than the first end portion 630d3. In other words, the first and second intersecting ribs can be arranged on opposite sides of each other, with the center of the base surface 630d in the sheet conveying direction D1 positioned between them.

[0110] It should be noted that the number of longitudinal ribs 803 can be one or more than three.

[0111] The grooved portion of the reinforcing rib

[0112] A groove portion 803b is provided in at least one longitudinal rib 803. The groove portion 803b is groove-shaped (recessed portion, notched portion), wherein a portion of the top portion 803a is recessed.

[0113] The groove portion 803b (provided in the longitudinal direction rib 803-1 (first intersecting rib)) Figure 11A The first groove portion 803b is an example of a first groove portion, and the groove portion 803b provided in the longitudinal direction rib 803-2 (second intersecting rib) is an example of a second groove portion. Furthermore, the groove portion 803b provided in the longitudinal direction rib 803-1 (first intersecting rib) is an example of a first shape, and the groove portion 803b provided in the longitudinal direction rib 803-2 (second intersecting rib) is an example of a second shape.

[0114] The groove portion 803b establishes communication between the outer peripheral surface of the pressure roller 62 and the base surface 630d of the lower frame 63, separated by longitudinal ribs 803. In other words, the groove portion 803b forms a path that allows air containing water vapor to move along the rotational direction of the pressure roller 62. The groove portion 803b allows air to move from the upstream side to the downstream side (or in the opposite direction) along the sheet conveying direction D1.

[0115] For example, in association with the rotation of the pressure roller 62, an airflow is generated that flows through the groove portion 803b. Airflow also occurs through the groove portion 803b as the sheet S passes through the clamping portion np1. Furthermore, it is acceptable to actively generate the airflow through the groove portion 803b by, for example, a blower fan installed in the main body 2 of the equipment.

[0116] The effect of the groove

[0117] In this example, by providing the groove portion 803b at the top portion 803a of the longitudinal rib 803, the stagnation of water vapor-containing air between the lower frame 63 and the pressure roller 62 can be suppressed. Subsequently, even in environments with high temperature and high humidity, such as when the sheet S contains a large amount of moisture, condensation on the pressure roller 62 can be suppressed. In other words, the airflow flowing through the groove portion 803b can expel water vapor generated from the sheet S during image fixing from the area near the outer peripheral surface of the pressure roller 62.

[0118] Similar to the groove portion 801b of the conveying direction rib 801, when a groove portion 803b is provided in each of the longitudinal direction ribs 803 adjacent to each other along the sheet conveying direction D1, the positions of the groove portions 803b in the longitudinal direction can overlap. That is, as... Figure 11A As shown at the left end, when viewed along the sheet conveying direction D1, the groove portion 803b-1 (first shape) of the first longitudinal direction rib 803-1 (first intersecting rib) and the groove portion 803b-2 (second shape) of the second longitudinal direction rib 803-2 (second intersecting rib) can overlap. In this case, the airflow of the pressure roller 62 in the rotational direction becomes smoother, thereby increasing the amount of air flowing through the space between the outer peripheral surface of the pressure roller 62 and the lower frame 63.

[0119] Conversely, when a groove portion 803b is provided in each of the longitudinal ribs 803 adjacent to each other along the sheet conveying direction D1, the positions of the groove portions 803b in the longitudinal direction can be arranged so that they do not overlap. That is, as... Figure 11A As shown at the right end, when viewed along the sheet conveying direction D1, the groove portions 803b-1 of the first longitudinal rib 803-1 and the groove portions 803b-2 of the second longitudinal rib 803-2 can be configured to not overlap. By arranging the groove portions 803b of adjacent longitudinal ribs 803 to not overlap as described above, water vapor can be uniformly discharged from the small space between adjacent longitudinal ribs 803.

[0120] It should be noted that, although Figure 11A A recessed portion 803b with a generally semi-circular shape is shown, but the shape of the recessed portion 803b is not limited to this, and, for example, rectangular or triangular shapes are acceptable. Furthermore, Figure 11AAn example is shown in which multiple recessed portions 803b are provided in a longitudinal rib 803 at approximately equal intervals along the longitudinal direction (Y direction); however, for example, only one recessed portion 803b may be provided at the central portion of the longitudinal rib 803. In the case of multiple longitudinal ribs 803, the recessed portions 803b may be formed only in some of the longitudinal ribs 803.

[0121] Modify Example

[0122] This example describes an instance of suppressing water vapor retention by providing a groove portion 803b in the longitudinal direction rib 803; however, as Figure 11B As shown, it is acceptable to form a through hole in the longitudinal rib 803 instead of a recessed portion 803b. In other words, a hole penetrating in the direction of rotation of the pressure roller 62 can be formed at a position closer to the root side (base surface 630d side) than the top portion 803a of the longitudinal rib 803. By forming a through hole 803c in the longitudinal rib 803, air transport between the small spaces separated by the longitudinal rib 803 is facilitated, and thus water vapor can be discharged.

[0123] Figure 11B This diagram illustrates an example of a first longitudinal rib 803-1 forming a through hole 803c (first through hole). A similar through hole 803c (second through hole) can be formed in a second longitudinal rib 803-2 (second intersecting rib). For example... Figure 11B As shown on the left, when viewed along the sheet conveying direction D1, the through-hole 803c-1 (first through-hole) of the first longitudinal rib 803-1 (first intersecting rib) and the through-hole 803c-2 (second through-hole) of the second longitudinal rib 803-2 (second intersecting rib) can overlap. In this case, the airflow in the sheet conveying direction D1 becomes smoother. Conversely, as Figure 11B As shown on the right, when viewed along the sheet conveying direction D1, the through holes 803c-1 of the first longitudinal rib 803-1 and 803c-2 of the second longitudinal rib 803-2 can be configured in a non-overlapping positional relationship. In this case, water vapor can be uniformly discharged from the small space between the longitudinal ribs 803-1 and 803-2.

[0124] Furthermore, this example describes a scenario where multiple recessed portions 803b of substantially equal size and shape are arranged side-by-side at substantially equal intervals. It is not limited to this; the sizes and shapes of the multiple recessed portions or through-holes may differ from each other, and the arrangement of the multiple recessed portions or through-holes in the longitudinal direction (Y direction) does not need to be at equal intervals. For example, if condensation is more likely to occur on the pressure roller 62 in the central region than in the peripheral region of the end portion 62b of the pressure roller 62, the spacing between adjacent recessed portions in the central region can be set to be narrower than the spacing between adjacent recessed portions in the regions at the two end portions. Furthermore, in similar cases, the size of the recessed portion in the central region can be increased relative to the size of the recessed portion in the regions at the two end portions.

[0125] Furthermore, while the groove portion 803b can be disposed in at least one of the plurality of longitudinal ribs 803, it can also be disposed in each of the plurality of longitudinal ribs 803. In this case, by aligning the arrangement of the groove portion 803b in the plurality of longitudinal ribs in the longitudinal direction, a smoother airflow along the rotation axis of the pressure roller 62 can be promoted. On the other hand, by changing the arrangement of the groove portion 803b in the plurality of longitudinal ribs in the longitudinal direction, water vapor can be uniformly discharged from the small space separated by the longitudinal ribs 803.

[0126] Example 3

[0127] Example 3 of this disclosure will now be described. This example differs from Example 1 in that the recessed portion is located at the intersection 802 of the conveying direction rib 801 and the longitudinal direction rib 803. In the following text, unless otherwise explicitly stated, elements represented by reference characters shared with Example 1 are considered to include substantially the same configuration and function as described in Example 1, and the following description will primarily discuss aspects that differ from Example 1.

[0128] Figure 12A This is a perspective view showing the lower frame 63. Figure 12B This is an enlarged view of the intersection portion 802 where the conveying direction rib 801 (first conveying direction rib 801-1) and the longitudinal direction rib 803 (first longitudinal direction rib 803-1) intersect.

[0129] like Figure 12A and Figure 12BAs shown, in the lower frame 63 of this example, a recessed portion 802a is provided at at least one of the intersecting portions 802 where the conveying direction rib 801 and the longitudinal direction rib 803 intersect. The recessed portion 802a is recessed toward a side further away from the axis of rotation of the pressure roller 62 than the top portion 801a of the conveying direction rib 801, and also recessed toward a side further away from the axis of rotation of the pressure roller 62 than the top portion 803a of the longitudinal direction rib 803. In other words, the top portion 802a of the intersecting portion 802 in the intersecting direction D2 is more recessed than the top portion 803a of the longitudinal direction rib 803-1 (the first intersecting rib) in the intersecting direction D2.

[0130] It can be said that the recessed portion 802a is a recessed groove portion of the top portion 801a of the conveying direction rib 801. Furthermore, it can be said that the recessed portion 802a is a recessed groove portion of the top portion 803a of the longitudinal direction rib 803. Therefore, the recessed portion 802a is an example of the first and second recessed groove portions of the first and second ribs described in Example 1, and also an example of the first and second recessed groove portions of the first and second intersecting ribs described in Example 2.

[0131] In this example, a longitudinal rib 803 intersects with a plurality of transport ribs 801. Then, a recessed portion 802a is provided at each of the plurality of intersecting portions 802 where the longitudinal rib 803 and the plurality of transport ribs 801 intersect.

[0132] The effect of the concave part

[0133] The recessed portion 802a in this example provides the same function as each of the recessed portion 801b of the conveying direction rib 801 and the recessed portion 803b of the longitudinal direction rib 803 described in Example 1. That is, by providing the recessed portion 802a, the small spaces separated by the longitudinal direction rib 803 and the conveying direction rib 801 are connected to each other, and the discharge of water vapor can be facilitated as airflow passes through the recessed portion 802a.

[0134] Furthermore, since the intersection portion 802 where the longitudinal direction rib 803 intersects with the conveying direction rib 801 inherently possesses high rigidity, the reduction in rigidity of the lower frame 63 can be suppressed by providing the groove portion 802a. Therefore, deflection of the lower frame 63 caused by applying pressure to the clamping portion np1, and creep deformation occurring due to extended operating duration, can be suppressed. Moreover, for example, since the rigidity of the lower frame 63 can be easily ensured without increasing the wall thickness of the lower frame 63 as a molding component, there is an advantage in reducing the weight of the fixing unit 6 (and the entire imaging device 1) and reducing the consumption of resin raw materials.

[0135] Modify Example

[0136] Although in Example 3, the recessed portion 802a is provided at all the intersecting portions 802 where the one longitudinal direction rib 803 and the plurality of conveying direction ribs 801 intersect, the recessed portion 802a may be provided only at some of the intersecting portions 802. Furthermore, the shape of the recessed portion 802a is not limited to... Figure 12B The shape shown.

[0137] Example 4

[0138] Example 4 of this disclosure will now be described. This example differs from Example 1 in that the through-hole 630h is provided in the portion of the lower frame 63 excluding the reinforcing rib 80. In the following, unless otherwise explicitly stated, elements indicated by reference characters shared with Example 1 are considered to include substantially the same configuration and function as described in Example 1, and the following description will primarily discuss aspects that differ from Example 1.

[0139] Figure 13 This shows a bottom view of the lower frame 63 when viewed from below. More specifically, Figure 13 The lower frame 63 of this example is shown, as shown from... Figure 4 The view is taken from bottom to top, perpendicular to both the longitudinal direction (Y direction) and the sheet conveying direction D1.

[0140] In the lower frame 63 of this example, a plurality of through holes 630h are formed. Each through hole 630h is formed at a location on the base surface 630d excluding the reinforcing ribs 80 (transfer direction rib 801 and longitudinal direction rib 803). Any one of the plurality of through holes 630h may be referred to as the first hole or the first through hole, and another of the plurality of through holes 630h may be referred to as the second hole or the second through hole. In this case, the first hole and the second hole (the first through hole and the second through hole) are aligned in the longitudinal direction.

[0141] In the lower frame 63 of this example, as an example of a through hole 630h, a lower through hole 630h-1 is formed, penetrating from the base surface 630d to the bottom surface 630b. The lower through hole 630h-1 penetrates the base surface 630d from top to bottom. Furthermore, in the example shown, six lower through holes 630h-1 are arranged at intervals between each other along the longitudinal direction.

[0142] A connection is established between the internal space of the lower frame 63 (the space between the bottom surface 630b and the outer peripheral surface of the pressure roller 62) and the external space of the lower frame 63 through the lower through hole 630h-1. In other words, the lower through hole 630h-1 forms a passage that allows water vapor to escape from the internal space of the lower frame 63 to the external space.

[0143] The effect of through holes

[0144] As shown in this example, by providing through holes (ventilation holes) in the lower frame 63, the retention of water vapor between the lower frame 63 and the pressure roller 62 can be suppressed. Therefore, even in environments with high temperature and high humidity, such as when the sheet S contains a large amount of water, condensation on the pressure roller 62 can be suppressed.

[0145] Furthermore, in this example, it is not necessarily necessary to include the through-holes and grooves in the reinforcing ribs 80. Therefore, condensation on the pressure rollers 62 can be suppressed while limiting the impact on the stiffness of the lower frame 63.

[0146] Modify Example

[0147] Although in Example 4, the lower through hole 630h-1 is formed on the bottom surface 630b of the lower frame 63, the through hole can be formed in other parts of the lower frame 63. Figure 14 This is a diagram showing a lower frame 63 according to a modified example (Modified Example 1), as viewed from the upstream side of the sheet transport direction D1. In Modified Example 1, a plurality of front through holes 630h-2 are formed as through holes 630h, penetrating from the base surface 630d of the lower frame 63 to the front surface 630a. The front through holes 630h-2 penetrate from the base surface 630d to the outside of the lower frame 63 in a direction opposite to the sheet transport direction D1.

[0148] Figure 15 This is a diagram showing the lower frame 63 according to another modified example (Modified Example 2), as viewed from the downstream side in the sheet conveying direction D1. In Modified Example 2, a plurality of rear through holes 630h-3 are formed as through holes 630h, penetrating from the base surface 630d of the lower frame 63 to the rear surface 630c. The rear through holes 630h-3 penetrate from the base surface 630d to the outside of the lower frame 63 in the sheet conveying direction D1.

[0149] One of the rear through holes 630h-3 can be referred to as the first hole or first through hole, and one of the front through holes 630h-2 can be referred to as the second hole or second through hole. For example, as indicated by the dashed line, the rear through hole 630h-3... Figure 14 As shown, when viewed along the sheet conveying direction D1, the rear through-hole 630h-3 (first hole, first through-hole) can overlap with the front through-hole 630h-2 (second hole, second through-hole). In other words, the position of the through-hole 630h leading to the front surface 630a of the lower frame 63 in the longitudinal direction can be aligned with the position of the through-hole 630h leading to the rear surface 630c of the lower frame 63 in the longitudinal direction. This allows air to flow more smoothly along the outer peripheral surface of the pressure roller 62.

[0150] On the other hand, when viewed along the sheet conveying direction D1, the rear through-hole 630h-3 (first hole, first through-hole) and the front through-hole 630h-2 (second hole, second through-hole) can have a non-overlapping positional relationship. In other words, the position of the through-hole 630h leading to the front surface 630a of the lower frame 63 in the longitudinal direction can be different from the position of the through-hole 630h leading to the rear surface 630c of the lower frame 63 in the longitudinal direction. As a result, it is easier to uniformly discharge water vapor from the space between the lower frame 63 and the outer peripheral surface of the pressure roller 62.

[0151] Figure 16 This is a diagram showing a lower frame 63 according to another modified example (Modified Example 3), as viewed from the upstream side in the sheet conveying direction D1. In Modified Example 3, instead of forming a through hole 630h in the lower frame 63, a recessed portion 630i is formed in the edge portion of the lower frame 63, penetrating from the base surface 630d of the lower frame 63 to the outside. Figure 16 In the example shown, one or more recessed portions 630i are formed, penetrating from the base surface 630d of the lower frame 63 to the front surface 630a. The recessed portions 630i are concave in shape, in which a portion of the upper edge of the front surface 630a is recessed downwards. The recessed portions 630i penetrate from the base surface 630d of the lower frame 63 to the outside of the lower frame in a direction opposite to the sheet conveying direction D1. Although in the example shown, six recessed portions 630i are arranged side-by-side in the longitudinal direction, the number of recessed portions 630i can vary. One of the six recessed portions 630i can be referred to as the first recess, and another of the six recessed portions 630i can be referred to as the second recess.

[0152] like Figure 15As shown by the dashed lines, a groove portion 630i can be formed in the rear surface 630c of the lower frame 63. This groove portion 630i is recessed in shape, in which a portion of the upper edge of the rear surface 630c is recessed downwards and formed to penetrate from the base surface 630d of the lower frame 63 to the rear surface 630c. In other words, this groove portion 630i penetrates from the base surface 630d of the lower frame 63 to the outside of the lower frame in the sheet conveying direction D1.

[0153] When the groove portion 630i-1 of the rear surface 630c is referred to as the first groove, the groove portion 630i-2 of the front surface 630a can be referred to as the second groove. For example... Figure 15 The groove portion 630i-2 specifically shown on the left side, when viewed along the sheet conveying direction D1, allows the groove portion 630i-1 on the rear surface 630c and the groove portion 630i-2 on the front surface 630a to overlap. Furthermore, as... Figure 15 The groove portion 630i-2 shown on the right side can be arranged so that it does not overlap when viewed along the sheet conveying direction D1.

[0154] Even in each of the above modified examples, by providing through holes or grooves in the lower frame 63, the stagnation of air containing water vapor between the lower frame 63 and the pressure roller 62 can be suppressed. Therefore, even in environments with high temperature and high humidity, such as when the sheet S contains a large amount of water, condensation on the pressure roller 62 can be suppressed. Furthermore, by providing through holes or grooves in the front surface 630a or rear surface 630c, there is the advantage that water vapor can be more easily expelled by the airflow generated by the sheet S when it passes through the fixing unit 6.

[0155] The number, arrangement, and shape of the through holes or grooves formed in the lower frame 63 are not limited to... Figures 13 to 16 The quantity, arrangement, and shape shown are acceptable, and for example, rectangular through-holes or recessed portions may be used. Furthermore, combining the through-holes and recessed portions described in Example 4 and modified Examples 1 to 3 is acceptable. For example, forming through-holes in each of the front surface 630a and rear surface 630c of the lower frame 63 is acceptable.

[0156] Example 5

[0157] Example 5 of this disclosure will now be described. While Examples 1 through 4 describe through-holes or recesses that function to drain water vapor generated from sheet S, this example differs from Examples 1 through 4 in that it includes through-holes and recesses for mounting a sensor (temperature detection unit) associated with the fixing unit 6. In the following description, unless otherwise explicitly stated, elements indicated by reference characters shared with Example 1 are considered to include substantially the same configuration and function as described in Example 1, and the following description will primarily discuss aspects that differ from Example 1.

[0158] In this example, a thermistor 618 is used as a temperature detection unit, which is configured to face the pressure roller 62. Figure 17 This is a schematic perspective view of the lower frame 63 according to this example. Figure 18 It is a cross-sectional view taken along an imaginary plane perpendicular to the longitudinal direction (Y direction), showing the lower frame 63, pressure roller 62 and thermistor 618.

[0159] like Figure 17 and Figure 18 As shown, the fixing unit 6 in this example includes a contact thermistor 618. The thermistor 618 is arranged inside the lower frame 63 so as to contact the outer peripheral surface of the pressure roller 62. Figure 18 It outputs a signal (e.g., voltage) corresponding to the temperature of the pressure roller 62. The thermistor 618 can be, for example, a thin-film thermistor.

[0160] The control unit of imaging device 1 acquires temperature information of pressure roller 62 based on a signal from the thermistor 618, and controls heater 611 of fixing unit 6 ( Figure 3 The temperature of the pressure roller 62 is controlled by the heat generated by the pressure roller 62. By properly controlling the temperature of the pressure roller 62, the productivity of the imaging device 1 can be improved, the fixing effect can be enhanced, and the image quality can be improved.

[0161] It should be noted that the thermistor 618 is an example of a temperature sensing unit, and it is acceptable to use a temperature sensing unit that includes other thermal sensing elements, such as thermocouples or platinum resistance temperature detectors. Furthermore, as in the modified example described below, the use of a non-contact temperature sensing unit (non-contact sensor) is also acceptable.

[0162] like Figure 17 and Figure 18As shown, in this example, a through-hole 805 (sensor mounting hole) and a recessed portion 806 are formed in the lower frame 63 for arranging the thermistor 618. The through-hole 805 extends from the base surface 630d of the lower frame 63 to the outside of the lower frame 63. Although in the illustrated example, the through-hole 805 leads to the rear surface 630c, the through-hole 805 may also lead to the front surface 630a or the bottom surface 630b.

[0163] The groove portion 806 is a groove shape (recessed portion, notch portion) formed in the reinforcing rib 80 of the lower frame 63. In this example, the groove portion 806 is formed in the longitudinal direction rib 803. The groove portion 806 is a recessed shape in which a portion of the top portion 803a of the longitudinal direction rib 803 (intersecting rib) is recessed, and this portion extends in the longitudinal direction to connect the transfer direction ribs 801 (first rib and second rib) positioned adjacent to each other in the longitudinal direction. When viewed along the direction extending from the longitudinal direction rib 803 toward the lower frame 63 (intersecting direction D2), the thermistor 618 (temperature sensing unit) includes a portion that overlaps with the groove portion 806.

[0164] A thermistor 618 is arranged through a through-hole 805 and faces the outer peripheral surface of the pressure roller 62. The thermistor 618 includes a head portion 618a (which contacts the outer peripheral surface of the pressure roller 62), a base portion 618c (which is supported by a lower frame 63), and a connecting portion 618b connecting the head portion 618a and the base portion 618c. The head portion 618a includes, for example, a thermistor element such as a negative temperature coefficient (NTC) type semiconductor element, whose resistance changes with temperature. The base portion 618c includes a connector that is electrically connected to a control unit for electrical connection with the imaging device 1. The connecting portion 618b includes a conductor for electrically connecting the thermistor element of the base portion 618c to the head portion 618a and for supporting the head portion 618a.

[0165] By forming a through-hole 805 in the lower frame 63, the thermistor 618 can be arranged to face the outer peripheral surface of the pressure roller 62. Furthermore, the thermistor 618 can be connected to wiring along the external wiring of the lower frame 63 via the through-hole 805.

[0166] Furthermore, by forming a recessed portion 806 in the reinforcing rib 80 (longitudinal rib 803) of the lower frame 63, the arrangement in which the head portion 618a contacts the outer peripheral surface of the pressure roller 62 can be easily achieved. If the recessed portion 806 is not provided, there may not be enough space to arrange the thermistor 618, and the installation of the thermistor 618 may become difficult; therefore, it may sometimes lead to a decrease in processing performance during assembly, and defects such as excessive contact between the head portion 618a and the pressure roller 62 may occur.

[0167] Although Figure 18 The image shows a contact thermistor 618 as an example, but as... Figure 19 As shown, a non-contact thermistor 618' can be used as a non-contact temperature detection unit. The non-contact thermistor 618' is arranged such that the head portion 618a' does not contact the outer peripheral surface of the pressure roller 62. The non-contact thermistor 618' outputs a signal corresponding to the temperature of the pressure roller 62 by detecting thermal radiation (infrared light) from the pressure roller 62. Even in this case, the non-contact thermistor 618' can be arranged by forming a through hole 805 in the lower frame 63 and a groove portion 806 in the reinforcing rib 80.

[0168] It should be noted that the non-contact thermistor 618' is an example of a non-contact temperature sensing unit, and non-contact temperature sensing units employing other sensing methods can also be used.

[0169] Figure 20A This is a schematic cross-sectional view showing the positional relationship between the longitudinal rib 803 and the thermistor 618 in a plane perpendicular to the sheet transport direction D1 and including the longitudinal rib 803. Figure 20A In the cross-sectional view shown, at least a portion of the thermistor 618 (temperature sensing unit) is located within the recessed portion 806. In other words, when viewed along the sheet transport direction D1, at least a portion of the thermistor 618 extends further inward into the recessed portion 806 compared to the top portion 803a (ridge) of the longitudinal rib 803. Specifically, when viewed along the intersecting direction D2, the overlapping portion of the thermistor 618 and the recessed portion 806 is located within the recessed portion 806. This configuration makes it easier to position the thermistor 618.

[0170] Furthermore, it can be said that Figure 20A The diagram shows a view taken tangentially to the outer peripheral surface of the pressure roller 62 at a position facing the head portion 618a of the thermistor 618. Therefore, in this example, when viewed tangentially to the outer peripheral surface of the pressure roller 62, at least a portion of the thermistor 618 is located further away from the pressure roller 62 than the top portion 803a of the longitudinal rib 803. Figure 20A (on the lower side of the middle).

[0171] Figure 20B This is a cross-sectional view schematically illustrating another positional relationship between the longitudinal rib 803 and the thermistor 618. Figure 20BIn the cross-sectional view shown, the entire thermistor 618 is located outside the groove portion 806. In other words, when viewed along the sheet conveying direction D1, the entire thermistor 618 is located closer to the pressure roller 62 than the top portion 803a (ridge) of the longitudinal rib 803. Figure 20B (on the upper side of the middle).

[0172] exist Figure 20B In the example shown, by providing the recessed portion 806 of the longitudinal rib 803, interference between the thermistor 618 and the longitudinal rib 803 due to dimensional or assembly tolerances of the thermistor 618 or the lower frame 63 components can be avoided. Therefore, even Figure 20B In the example shown, it is also easier to arrange the thermistor 618 for detecting the temperature of the pressure roller 62.

[0173] Modify Example

[0174] In Example 5, the thermistor 618 for detecting the temperature of the pressure roller 62 is provided at only one location; however, it is not limited to this, and the thermistor 618 can be provided at multiple locations. For example, sometimes an additional thermistor is provided at the end portion of the pressure roller 62 in the longitudinal direction to detect the temperature. In this case, the control unit of the imaging device 1 can monitor the temperature at the end portion of the pressure roller 62.

[0175] Here, when imaging is performed on recording material whose width in the longitudinal direction is shorter than the heating area of ​​heater 611, the temperature rise of the pressure roller 62 (and belt 614) in the region where the recording material does not pass through is referred to as non-sheet passage area temperature rise. Non-sheet passage area temperature rise can cause damage or deterioration of components due to high temperatures, and may lead to image defects when imaging is subsequently performed on recording material with increasing width. Without the additional thermistor, when imaging on narrow-width recording material, the adverse effects of non-sheet passage area temperature rise can be prevented by reducing productivity. On the other hand, by using the additional thermistor to monitor the temperature at the end portion of the pressure roller 62, imaging can be performed at high productivity while avoiding the adverse effects of non-sheet passage area temperature rise. Therefore, by providing the additional thermistor at the end portion of the pressure roller 62, the productivity of the imaging device 1 can be improved.

[0176] When multiple temperature detection units are arranged as described above, it is acceptable to form through holes 805 and groove portions 806 in the lower frame 63 corresponding to each of the multiple temperature detection units. This allows for the easy arrangement of contact temperature detection units that contact the outer peripheral surface of the pressure roller 62, or non-contact temperature detection units located near the pressure roller 62.

[0177] According to the technology disclosed herein, a novel configuration of a fixing unit that improves upon conventional technology can be provided.

[0178] Supplement to this disclosure

[0179] This disclosure includes at least the following configurations and / or methods.

[0180] Configuration 1

[0181] A fixing unit configured to fix an image onto a recording material, the fixing unit comprising:

[0182] Circular belt;

[0183] A heater configured to heat the inner surface of the belt;

[0184] A pressure roller, the pressure roller including a roller portion formed of rubber and configured to form a clamping portion by clamping the belt with the heater, such that the recording material is conveyed in a conveying direction through the clamping portion; and

[0185] A frame, formed of resin, configured to rotatably support the pressure roller and arranged to face the roller portion in the longitudinal direction of the pressure roller.

[0186] The frame includes a base surface facing the outer peripheral surface of the roller portion in the longitudinal direction.

[0187] The base surface includes a first rib and a second rib extending along an intersecting direction that intersects both the conveying direction and the longitudinal direction.

[0188] When viewed along the longitudinal direction, the tip portions of both the first rib and the second rib have an arc shape along the outer peripheral surface of the roller portion.

[0189] The first rib and the second rib are aligned in the longitudinal direction.

[0190] The base surface includes a first intersecting rib having a first shape and a second intersecting rib having a second shape.

[0191] The first intersecting rib and the second intersecting rib are located between the first rib and the second rib in the longitudinal direction and extend along the longitudinal direction and the intersecting direction.

[0192] The first intersecting rib and the second intersecting rib are arranged at different positions in the conveying direction.

[0193] The first shape is either a first through hole extending through the first intersecting rib along the conveying direction or a groove formed in the top portion of the first intersecting rib in the intersecting direction.

[0194] The second shape is either a second through hole extending through the second intersecting rib along the conveying direction or a groove portion formed in the top portion of the second intersecting rib in the intersecting direction.

[0195] Configuration 2

[0196] According to the fixing unit described in configuration 1

[0197] The end portion of the base surface in the conveying direction is referred to on one side as the first end portion, and the other side of the end portion as the second end portion.

[0198] In the conveying direction, the first intersecting rib is positioned closer to the first end portion than to the second end portion, and

[0199] In the conveying direction, the second intersecting rib is positioned closer to the second end portion than to the first end portion.

[0200] Configuration 3

[0201] According to configuration 1 or 2, the fixing unit

[0202] The first intersecting rib and the second intersecting rib face each other in the transmission direction, and

[0203] When viewed along the conveying direction, the first shape overlaps with the second shape.

[0204] Configuration 4

[0205] According to configuration 1 or 2, the fixing unit

[0206] The first intersecting rib and the second intersecting rib face each other in the transmission direction, and

[0207] When viewed along the conveying direction, the first shape does not overlap with the second shape.

[0208] Configuration 5

[0209] A fixing unit configured to fix an image onto a recording material, the fixing unit comprising:

[0210] Circular belt;

[0211] A heater configured to heat the inner surface of the belt;

[0212] A pressure roller, the pressure roller including a roller portion formed of rubber and configured to form a clamping portion by clamping the belt with the heater, such that the recording material is conveyed through the clamping portion in a conveying direction; and

[0213] A frame, formed of resin, configured to rotatably support the pressure roller and arranged to face the roller portion in the longitudinal direction of the pressure roller.

[0214] The frame includes a base surface that faces the roller portion in an intersection direction that intersects both the conveying direction and the longitudinal direction.

[0215] The base surface includes a first rib and a second rib extending along the intersecting direction.

[0216] When viewed along the longitudinal direction, the tip portions of both the first rib and the second rib have an arc shape along the outer peripheral surface of the roller portion.

[0217] The first rib and the second rib are aligned in the longitudinal direction.

[0218] The frame includes a first through hole and a second through hole, and

[0219] The first through hole and the second through hole are formed at the locations of the first rib and the second rib excluding the base surface, and extend from the base surface to the outside of the frame.

[0220] Configuration 6

[0221] According to the fixing unit described in configuration 5

[0222] When viewed along the conveying direction, the first through hole and the second through hole overlap.

[0223] Configuration 7

[0224] According to the fixing unit described in configuration 5

[0225] When viewed along the conveying direction, the first through hole and the second through hole do not overlap.

[0226] Configuration 8

[0227] According to the fixing unit described in configuration 5

[0228] The first through hole and the second through hole are aligned along the longitudinal direction.

[0229] Other embodiments

[0230] While this disclosure has been described with reference to embodiments, it should be understood that this disclosure is not limited to the disclosed embodiments. The scope of the appended claims is to be given the broadest interpretation in order to cover all such modifications as well as equivalent structures and functions.

Claims

1. A fixing unit, comprising: Circular belt; A heater configured to heat the inner surface of the belt; A pressure roller, the pressure roller including a roller portion formed of rubber and configured to form a clamping portion by clamping the belt with the heater, such that recording material is conveyed through the clamping portion in a conveying direction; as well as A frame, formed of resin, configured to rotatably support the pressure roller and arranged to face the roller portion in the longitudinal direction of the pressure roller. The frame includes a base surface facing the outer peripheral surface of the roller portion in the longitudinal direction. The base surface includes a first rib and a second rib extending along an intersecting direction that intersects both the conveying direction and the longitudinal direction. When viewed along the longitudinal direction, the tip portions of both the first rib and the second rib have an arc shape along the outer peripheral surface of the roller portion. The first rib and the second rib are aligned in the longitudinal direction. The first rib is formed with a first shape. The second rib has a second shape. The first shape is either a first through hole extending through the first rib along the longitudinal direction or a first groove portion formed in a part of the arcuate shape of the first rib. The second shape is either a second through hole extending through the second rib along the longitudinal direction or a second groove portion formed in a part of the arcuate shape of the second rib.

2. The fixing unit according to claim 1, in, When one side of the end portion of the base surface in the longitudinal direction is referred to as the first end portion and the other side of the end portion is referred to as the second end portion, In the longitudinal direction, the first rib is positioned closer to the first end portion than to the second end portion, and, In the longitudinal direction, the second rib is positioned closer to the second end portion than to the first end portion.

3. The fixing unit according to claim 1, The first rib and the second rib face each other in the longitudinal direction, and in, When viewed along the longitudinal direction, the first shape overlaps with the second shape.

4. The fixing unit according to claim 1, The first rib and the second rib face each other along the longitudinal direction, and in, When viewed along the longitudinal direction, the first shape does not overlap with the second shape.

5. The fixing unit according to any one of claims 1 to 4, The base surface includes a first intersecting rib extending along the longitudinal direction to connect the first rib and the second rib. The base surface includes a second intersecting rib extending along the longitudinal direction to connect the first rib and the second rib. and The second intersecting rib faces the first intersecting rib in the transmission direction.

6. The fixing unit according to claim 5, in, In the case where the portion where the first rib intersects with the first intersecting rib is referred to as the intersecting portion. The top portion of the intersecting portion in the intersecting direction is recessed relative to the top portion of the first intersecting rib in the intersecting direction.

7. The fixing unit according to any one of claims 1 to 4, The frame includes a first hole and a second hole extending from the base surface of the frame to the outside of the frame.

8. The fixing unit according to claim 7, The first hole extends from the base surface of the frame toward the conveying direction to the outside of the frame, and The second hole extends from the base surface of the frame in a direction opposite to the conveying direction to the outside of the frame.

9. The fixing unit according to claim 8, in, When viewed along the conveying direction, the first hole and the second hole overlap.

10. The fixing unit according to claim 7, The first hole and the second hole are aligned in the longitudinal direction.

11. The fixing unit according to any one of claims 1 to 4, The frame includes a first groove and a second groove, which, when viewed along the conveying direction, extend from the base surface of the frame to the outside of the frame.

12. The fixing unit according to claim 11, The first groove extends from the base surface of the frame toward the conveying direction to the outside of the frame, and The second groove extends from the base surface of the frame in a direction opposite to the conveying direction to the outside of the frame.

13. The fixing unit according to claim 12, in, When viewed along the conveying direction, the first groove and the second groove overlap.

14. The fixing unit according to claim 11, The first groove and the second groove are aligned in the longitudinal direction.

15. A fixing unit, comprising: Circular belt; A heater configured to heat the inner surface of the belt; A pressure roller, the pressure roller including a roller portion formed of rubber and configured to form a clamping portion by clamping the belt with the heater, such that recording material is conveyed through the clamping portion in a conveying direction; as well as A frame, formed of resin, configured to rotatably support the pressure roller and arranged to face the roller portion in the longitudinal direction of the pressure roller. The frame includes a base surface facing the outer peripheral surface of the roller portion in the longitudinal direction. The base surface includes a first rib and a second rib extending along an intersecting direction that intersects both the conveying direction and the longitudinal direction. When viewed along the longitudinal direction, the tip portions of both the first rib and the second rib have an arc shape along the outer peripheral surface of the roller portion. The first rib and the second rib are aligned in the longitudinal direction. The base surface includes a first intersecting rib having a first shape and a second intersecting rib having a second shape. The first intersecting rib and the second intersecting rib are disposed between the first rib and the second rib in the longitudinal direction and extend along the longitudinal direction and the intersecting direction. The first intersecting rib and the second intersecting rib are arranged at different positions in the conveying direction. The first shape is either a first through hole extending through the first intersecting rib along the conveying direction or a groove formed in the top portion of the first intersecting rib in the intersecting direction. The second shape is either a second through hole extending through the second intersecting rib along the conveying direction or a groove portion formed in the top portion of the second intersecting rib in the intersecting direction.

16. A fixing unit, comprising: Circular belt; A heater configured to heat the inner surface of the belt; A pressure roller, the pressure roller including a roller portion formed of rubber and configured to form a clamping portion by clamping the belt with the heater, such that recording material is conveyed through the clamping portion in a conveying direction; A frame formed of resin, configured to rotatably support the pressure roller and arranged to face the roller portion in the longitudinal direction of the pressure roller; as well as A temperature detection unit is used to detect the temperature of the pressure roller. The frame includes a base surface that faces the roller portion in an intersection direction that intersects both the conveying direction and the longitudinal direction. The base surface includes a first rib and a second rib extending along the intersecting direction. When viewed along the longitudinal direction, the tip portions of both the first rib and the second rib have an arc shape along the outer peripheral surface of the roller portion. The first rib and the second rib are aligned in the longitudinal direction. The frame has a through hole extending from the base surface to the outside of the frame and located between the first rib and the second rib. The temperature detection unit is configured to pass through the through hole and face the pressure roller.

17. The fixing unit according to claim 16, The temperature detection unit is configured to contact the pressure roller.

18. The fixing unit according to claim 16, The temperature detection unit is a non-contact sensor configured not to contact the pressure roller.

19. The fixing unit according to any one of claims 16 to 18, The frame includes intersecting ribs extending along the longitudinal direction to connect the first rib and the second rib. The top portion of the intersecting ribs is formed with a groove, and in, When viewed along the direction in which the intersecting ribs extend toward the frame, the temperature detection unit includes a portion that overlaps with the groove.

20. The fixing unit according to claim 19, The portion therein is located within the groove.

Images