Heater and image forming apparatus

Abstract

To provide a heater that can suppress occurrence of warpage of the heater even if its base part is formed of a metal material, and can simplify a configuration of a fixing unit, and an image forming apparatus.SOLUTION: A heater according to an embodiment is a heater provided on a fixing unit of an image forming apparatus. The heater is provided with: a base part that exhibits a plate shape, extends in a first direction, has a convex curved surface on one face, has a recess opening in the convex curved surface and extending in the first direction, and includes metal; an insulating layer that is provided on a bottom face of the recess; heating elements that are provided on the insulating layer and extend in the first direction; and a protection part that covers the heating elements.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] Embodiments of the present invention relate to a heater and an image forming apparatus.

Background Art

[0002] Image forming apparatuses such as copiers and printers are provided with heaters for fixing toner. Generally, such a heater has a long flat base, a heating element provided on one surface of the base and extending in the longitudinal direction of the base, and a protective part covering the heating element.

[0003] The base is made of a material having heat resistance, insulation, and high thermal conductivity. The base is formed of, for example, ceramics such as aluminum oxide. Also, the base may be, for example, a metal plate whose surface is coated with an insulating material.

[0004] The protective part is made of a material having heat resistance, insulation, high thermal conductivity, and high chemical stability. For example, the protective part is formed of ceramics, glass, or the like.

[0005] Here, if the material of the base is metal, improvement in the rigidity of the base and reduction in manufacturing cost can be achieved. However, if the material of the base is metal, the material of the base and the material of the protective part will be different, so thermal stress will occur due to the difference in the coefficient of thermal expansion of the materials. When thermal stress occurs, the heater is likely to warp. Furthermore, since the coefficient of thermal expansion of metal is higher than that of ceramics or the like, the thermal stress is likely to increase. When the thermal stress increases, the warp of the heater increases.

[0006] When the warp of the heater increases, the distance between the heater and the object to be heated varies, and there is a possibility that heating unevenness occurs in the object to be heated. Furthermore, generally, such a heater is attached to a stay of a fixing unit provided in an image forming apparatus. Therefore, the configuration of the fixing unit becomes complicated, and it has been difficult to reduce the manufacturing cost.

[0007] Therefore, there was a need to develop a technology that could suppress warping of the heater even when the base material was made of metal, and that could also simplify the structure of the fixing part. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2007-240606 [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] The problem that the present invention aims to solve is to provide a heater and an image forming apparatus that can suppress warping of the heater even when the base material is metal, and that can simplify the configuration of the fixing part. [Means for solving the problem]

[0010] The heater according to this embodiment is a heater provided in the fixing section of an image forming apparatus. The heater has a plate shape, extends in a first direction, one surface is a convex curved surface, and has a recess opening in the convex curved surface and extending in the first direction, and a base portion containing metal and the bottom surface of the recess Directly fired and containing inorganic materials An insulating layer and; on the insulating layer Direct firing , a heating element extending in the first direction; The insulating layer is directly fired upon, It comprises a protective part that covers the aforementioned heating element. The base portion has a curved shape in the thickness direction, and the recess opens onto the curved outer surface of the base portion, which is the convex curved surface. [Effects of the Invention]

[0011] According to embodiments of the present invention, even when the base material is metal, it is possible to suppress warping of the heater and simplify the configuration of the fixing part, thereby providing a heater and an image forming apparatus. [Brief explanation of the drawing]

[0012] [Figure 1] It is a schematic front view for exemplifying the heater according to this embodiment. [Figure 2] It is a schematic enlarged cross-sectional view in the A-A line direction of the heater in FIG. 1. [Figure 3] It is a schematic front view for exemplifying the heater according to another embodiment. [Figure 4] It is a schematic enlarged cross-sectional view in the B-B line direction of the heater in FIG. 3. [Figure 5] It is a schematic diagram for exemplifying the image forming apparatus according to this embodiment. [Figure 6] It is a schematic diagram for exemplifying the fixing unit. <http: / / pats.dl.itd.co.jp / patimg / [Figure 7] It is a schematic diagram for exemplifying the fixing unit according to another embodiment.

Embodiments for Carrying Out the Invention

[0013] Hereinafter, embodiments will be exemplified while referring to the drawings. In each drawing, the same reference numerals are assigned to the same components, and detailed descriptions thereof are omitted as appropriate. Also, the arrows X, Y, and Z in each drawing represent three mutually orthogonal directions.

[0014] (Heater) FIG. 1 is a schematic front view for exemplifying the heater 1 according to this embodiment. Note that FIG. 1 is a view of the heater 1 seen from the side where the heat generating portion 20 is provided. FIG. 2 is a schematic enlarged cross-sectional view in the A-A line direction of the heater 1 in FIG. 1. As shown in FIGS. 1 and 2, the heater 1 has, for example, a base portion 10, an insulating layer 11, a heat generating portion 20, a wiring portion 30, and a protection portion 40.

[0015] The base portion 10 has a plate shape and a shape curved in the thickness direction. The base portion 10 extends in the X direction (corresponding to an example of the first direction). A concave portion 10a1 is provided on the curved outer surface 10a, which is a convex curved surface, of the base portion 10. The concave portion 10a1 opens to the outer surface 10a and extends in the X direction at the center of the outer surface 10a.

[0016] The thickness T of the base 10 is, for example, about 0.5 mm to 1.0 mm. The dimension of the base 10 in the X direction can be appropriately changed according to the size of the object to be heated (for example, paper). The radius of curvature R of the outer surface 10a in the vicinity of the recess 10a1 is, for example, 0.1 mm or more. If the radius of curvature R of the outer surface 10a is set like this, the conveyance of the object to be heated passing through the heater 1 becomes smooth. Also, it is preferable that there is no step at the connection portion between the outer surface 10a of the base 10 and the outer surface 40a of the protective portion 40. If it is like this, the conveyance of the object to be heated passing through the heater 1 becomes even smoother.

[0017] The base 10 is formed of a material having heat resistance and high thermal conductivity. The base 10 can be formed of, for example, a metal such as stainless steel or an aluminum alloy. The base 10 can be formed by, for example, plastic working such as bending or pressing, or drawing.

[0018] The thermal conductivity of a metal is higher than that of an inorganic material such as ceramics. Therefore, if the base 10 is formed of a metal, it is possible to suppress the occurrence of an in-plane distribution in the temperature of the heater 1. Also, it is possible to improve the rigidity of the base 10, suppress the occurrence of cracks and chips, and reduce the manufacturing cost. Details regarding suppression of warping in the base 10 will be described later.

[0019] The insulating layer 11 is provided on the bottom surface 10a2 of the recess 10a1 of the base 10. The insulating layer 11 extends in the X direction. The insulating layer 11 covers at least the region where the heat generating portion 20 is provided on the bottom surface 10a2 of the recess 10a1. The insulating layer 11 is formed of a material having heat resistance and insulation properties. The insulating layer 11 can be formed of, for example, an inorganic material such as ceramics. The insulating layer 11 can be formed by, for example, applying a paste-like material to the bottom surface 10a2 of the recess 10a1 using a screen printing method or the like, and curing this using a firing method or the like.

[0020] The heating element 20 converts the applied power into heat (Joule heat). The heating element 20 is provided on top of the insulating layer 11. The heating element 20 and the base 10 are insulated from each other by the insulating layer 11. The heating section 20 includes, for example, a heating element 21 and a heating element 22. While the example given illustrates the provision of heating elements 21 and 22, the number and size of the heating elements can be appropriately changed depending on the size of the base 10 and the size of the object to be heated. Furthermore, multiple types of heating elements with different lengths, widths, and shapes can be provided. In other words, at least one heating element is sufficient.

[0021] The heating elements 21 and 22 can be arranged side by side with a predetermined interval in the Y direction (the short direction of the insulating layer 11). The heating elements 21 and 22 extend, for example, in the X direction (the longitudinal direction of the insulating layer 11).

[0022] The dimensions (length dimensions) of heating elements 21 and 22 in the X direction can be, for example, approximately the same. In this case, it is preferable that the centers of heating elements 21 and 22 are located on the straight line 1a. That is, it is preferable that heating elements 21 and 22 each have a shape that is symmetrical with respect to the straight line 1a as the axis of symmetry.

[0023] When attaching the heater 1 to the image forming apparatus 100, for example, the straight line 1a is aligned with the center line of the transport path of the object to be heated. In this way, even if the dimensions or position of the object to be heated change in a direction perpendicular to the transport direction, the object to be heated can be heated substantially uniformly.

[0024] The electrical resistance values ​​of heating elements 21 and 22 can be approximately the same or different. For example, by making the dimensions in the X direction (length), Y direction (width), and Z direction (corresponding to an example of a second direction) (thickness) of heating elements 21 and 22 approximately the same, the electrical resistance values ​​of heating elements 21 and 22 can be made approximately the same. Alternatively, by changing at least one of these dimensions, the electrical resistance values ​​of heating elements 21 and 22 can be made different. Furthermore, by changing the material, the electrical resistance values ​​of heating elements 21 and 22 can be made different.

[0025] Furthermore, the electrical resistance per unit length of the heating element 21 can be made approximately uniform in the X direction. For example, the dimensions of the heating element 21 in the Y direction (width dimension) and the Z direction (thickness dimension) can be made approximately constant. The shape of the heating element 21 as viewed from the Z direction can be, for example, an approximately rectangular shape extending in the X direction.

[0026] Furthermore, the electrical resistance per unit length of the heating element 22 can be made approximately uniform in the X direction. For example, the dimensions of the heating element 22 in the Y direction (width dimension) and the Z direction (thickness dimension) can be made approximately constant. The shape of the heating element 22 as viewed from the Z direction can be, for example, an approximately rectangular shape extending in the X direction.

[0027] The heating elements 21 and 22 can be formed using, for example, ruthenium oxide (RuO2), silver-palladium (Ag-Pd) alloy, etc. The heating elements 21 and 22 can be formed by, for example, applying a paste-like material onto the insulating layer 11 using a screen printing method, and then curing it using a firing method, etc.

[0028] The wiring section 30 is provided on top of the insulating layer 11. The wiring section 30 includes, for example, terminals 31, terminals 32, wiring 33, wiring 34, and wiring 35.

[0029] Terminals 31 and 32 are provided, for example, near one end of the base 10 in the X direction. Terminals 31 and 32 are provided, for example, side by side in the X direction. Terminals 31 and 32 are electrically connected to, for example, a power supply, via connectors and wiring.

[0030] The wiring 33 is provided, for example, on the side of the base 10 where the terminal 31 is located, in the X direction. The wiring 33 extends in the X direction. The wiring 33 is electrically connected to the terminal 31 and to the terminal 31 side end of the heating element 21.

[0031] The wiring 34 is provided, for example, near the end of the base 10 opposite to the side where terminals 31 and 32 are provided, in the X direction. The end of the heating element 21 opposite to the wiring 33 side, and the end of the heating element 22 opposite to the wiring 35 side are electrically connected to the wiring 34.

[0032] The wiring 35 is provided, for example, on the side of the base 10 where the terminal 32 is located, in the X direction. The wiring 35 extends in the X direction. The wiring 35 is electrically connected to the terminal 32 and to the terminal 32 side end of the heating element 22.

[0033] The wiring section 30 (terminals 31, 32 and wiring 33-35) is formed using a material containing, for example, silver or copper. For example, terminals 31, 32 and wiring 33-35 can be formed by applying a paste-like material onto the insulating layer 11 using a screen printing method or the like, and then curing it using a firing method or the like.

[0034] The protective section 40 is provided on the insulating layer 11 and covers the heating section 20 (heating elements 21 and 22) and a portion of the wiring section 30 (wiring 33, wiring 34, and wiring 35). In this case, terminals 31 and 32 of the wiring section 30 are exposed from the protective section 40.

[0035] The protective part 40 extends in the X direction. The protective part 40 has the functions of insulating the heat-generating part 20 and a portion of the wiring part 30, transferring heat generated in the heat-generating part 20, and protecting the heat-generating part 20 and a portion of the wiring part 30 from external forces, corrosive gases, etc. The protective part 40 is made of a material that has heat resistance and insulation properties, and high chemical stability and thermal conductivity. The protective part 40 is made of, for example, ceramics or glass. In this case, the protective part 40 can also be made using glass to which a filler containing a material with high thermal conductivity, such as aluminum oxide, has been added. The thermal conductivity of the glass to which the filler has been added can be, for example, 2 [W / (m·K)] or more.

[0036] Furthermore, the heater 1 may be further provided with a detection unit for detecting the temperature of the heat-generating part 20. The detection unit may be, for example, a thermistor. The detection unit may be provided, for example, on the insulating layer 11, and on at least one of the regions of the concave inner surface 10b of the base 10 that faces the insulating layer 11 and faces the outer surface 10a.

[0037] When the detection unit is provided on the insulating layer 11, the detection unit and the wiring and terminals electrically connected to the detection unit can be covered by the protective unit 40. The terminals electrically connected to the detection unit can be exposed from the protective unit 40.

[0038] When the detection unit is provided on the concave inner surface 10b of the base 10, an insulating layer can be provided on the inner surface 10b, and the detection unit, as well as the wiring and terminals electrically connected to the detection unit, can be provided on the insulating layer. The insulating layer can be the same as that of insulating layer 11. In addition, the wiring electrically connected to the detection unit can be covered by a protective unit. The terminals electrically connected to the detection unit can be exposed from the protective unit. The protective unit can be the same as that of protective unit 40.

[0039] Next, we will explain how to suppress warping in the base 10. As mentioned above, the base portion 10 is formed from a metal such as stainless steel or an aluminum alloy. On the other hand, the protective portion 40 is formed from, for example, ceramics, glass, or glass with fillers added. The insulating layer 11 is formed from, for example, an inorganic material such as ceramics.

[0040] Therefore, the thermal expansion coefficient of the base 10 differs from that of the protective part 40 and the insulating layer 11. Also, when the heater 1 is used and the heating element 20 (heating elements 21 and 22) is heated, the base 10, protective part 40, and insulating layer 11 are heated. When the protective part 40 and insulating layer 11 are fired during the manufacturing of the heater 1, the base 10, protective part 40, and insulating layer 11 are heated. Therefore, thermal stress is generated during the use and manufacturing of the heater 1 due to the difference in the thermal expansion coefficients of the materials. When thermal stress occurs, there is a risk that the heater 1 may warp. Furthermore, since the thermal expansion coefficient of metals is higher than that of ceramics and other materials, the heater 1 is more prone to warping.

[0041] Furthermore, the base on which the insulating layer 11, the heating element 20, and the protective element 40 are provided is generally a flat plate base. Since a flat plate base has low bending rigidity, when thermal stress occurs in a typical heater, the heater warps significantly. In this case, if the length of the flat plate base in the Y direction (width direction) is short, the length of the flat plate base in the X direction is long, or the thickness of the flat plate base is thin, the heater warps even more.

[0042] As shown in Figure 2, the base portion 10 has a plate-like shape and is curved in the thickness direction. Having a base portion 10 with such a shape allows for increased bending rigidity of the base portion 10. If the bending rigidity of the base portion 10 is increased, even if thermal stress is generated due to differences in the thermal expansion coefficients of the materials, warping of the heater 1 can be suppressed.

[0043] Furthermore, a typical heater having a flat base is attached to a stay in the fixing unit of an image forming apparatus. Since the base portion 10 has a curved shape in the thickness direction, the base portion 10 can function as a stay. Therefore, the heater 1 can be used directly with the fixing portion 200 described later, and the stay can be omitted. If the stay can be omitted, the configuration of the fixing portion 200 can be simplified.

[0044] In this case, the Z-direction dimension L of the base 10 is preferably 1 mm or more and 5 mm or less. This ensures that even if the heater 1 is used as is in the fixing section 200, the transport of the object to be heated passing through the heater 1 is smooth. Furthermore, by setting the Z-direction dimension L of the base 10 in this manner, the bending rigidity of the base 10 can be increased. For example, even if the thickness T of the base 10 is around 0.5 mm to 1.0 mm, sufficient bending rigidity can be obtained against the generated thermal stress.

[0045] Furthermore, the dimension W of the base 10 in the Y direction is preferably 4 mm or more and 10 mm or less. This increases the bending rigidity of the base 10, so that even if the thickness T of the base 10 is about 0.5 mm to 1.0 mm, sufficient bending rigidity can be obtained against the generated thermal stress.

[0046] As described above, with the heater 1 according to this embodiment, even if the material of the base 10 is metal, warping of the heater 1 can be suppressed, and the structure of the fixing part 200 can be simplified.

[0047] Figure 3 is a schematic front view illustrating a heater 50 according to another embodiment. Figure 3 shows the heater 50 as viewed from the side where the heating element 20 is located. Figure 4 is a schematic enlarged cross-sectional view of the heater 50 in the direction of line BB in Figure 3.

[0048] As shown in Figures 3 and 4, the heater 50 includes, for example, a base 60, an insulating layer 11, a heat-generating section 20, a wiring section 30, a protective section 40, and a reinforcing section 70. Furthermore, similar to the heater 1 described above, a detection section for detecting the temperature of the heat-generating section 20 may also be provided.

[0049] Furthermore, it is preferable that the centers of the heating elements 21 and 22 are located on the straight line 60a. That is, it is preferable that the heating elements 21 and 22 each have a shape that is symmetrical with respect to the straight line 60a as the axis of symmetry.

[0050] When attaching the heater 50 to the image forming apparatus 100, for example, the straight line 60a is aligned with the center line of the transport path of the object to be heated. In this way, even if the dimensions or position of the object to be heated change in a direction perpendicular to the transport direction, the object to be heated can be heated substantially uniformly.

[0051] The base portion 60 has a first portion 61 and a second portion 62. The first portion 61 and the second portion 62 can be formed integrally. The base portion 60 (first portion 61 and second portion 62) can be formed from a metal such as stainless steel or an aluminum alloy. The base portion 60 can be formed by plastic deformation processes such as bending or pressing, or by drawing.

[0052] The first portion 61 is plate-shaped. The first portion 61 extends in the X direction. A recess 61a1 is provided on the outer surface 61a of the first portion 61 in the Z direction. The recess 61a1 opens to the outer surface 61a. The recess 61a1 extends in the X direction through the center of the outer surface 61a. Similar to the recess 10a1 described above, an insulating layer 11 is provided on the bottom surface 61a2 of the recess 61a1. A heating element 20, a wiring element 30, and a protective element 40 are provided on the insulating layer 11. The protective element 40 covers the heating element 20 (heating elements 21 and 22) and a part of the wiring element 30 (wiring 33, wiring 34, and wiring 35). Terminals 31 and 32 of the wiring element 30 are exposed from the protective element 40.

[0053] The outer surface 61a of the first portion 61 can be a convex curved surface. The radius of curvature R1 of the outer surface 61a near the recess 61a1 is, for example, 0.1 mm or more. Setting the radius of curvature R1 of the outer surface 61a in this way allows for smooth transport of the object to be heated through the heater 50. Furthermore, it is preferable that there be no step at the connection between the outer surface 61a of the first portion 61 and the outer surface 40a of the protective portion 40. Doing so further facilitates the transport of the object to be heated through the heater 50.

[0054] The second portion 62 is plate-shaped and is provided in pairs. The second portion 62 is provided on each of the periphery edges in the Y direction of the inner surface 61b of the first portion 61, which is opposite the outer surface 61a. The second portion 62 protrudes from the inner surface 61b in the Z direction. The pair of second portions 62 face each other.

[0055] The dimensions of the base portion 60 (first portion 61 and second portion 62) in the X direction can be appropriately changed according to the size of the object to be heated. The thickness T1 of the first part 61 and the thickness T2 of the second part 62 are, for example, about 0.5 mm to 1.0 mm.

[0056] The Y-direction dimension W1 of the base 60 (the Y-direction dimension of the first part 61) is, for example, about 4 mm to 10 mm. The Z-direction dimension L1 of the base 60 can be between 1 mm and 5 mm.

[0057] In other words, the Y-direction dimension W1 of the base 60 can be made smaller than the Y-direction dimension W of the base 10 as described above. Also, the Z-direction dimension L1 of the base 60 can be made smaller than the Z-direction dimension L of the base 10 as described above. Therefore, the base 60 can be made smaller.

[0058] However, if the dimensions W1 in the Y direction and L1 in the Z direction of the base 60 are set in this way, the bending rigidity of the base 60 becomes smaller than that of the base 10. Therefore, the heater 50 is provided with a reinforcing section 70.

[0059] As shown in Figure 4, the reinforcing portion 70 is provided on the inner surface 61b side of the first portion 61. The reinforcing portion 70 is provided between one second portion 62 and the other second portion 62. The reinforcing portion 70 extends in the Z direction. The reinforcing portion 70 protrudes from the inner surface 61b side of the first portion 61. The reinforcing portion 70 has a plate-like shape and is curved in the thickness direction. For example, the shape of the reinforcing portion 70 as viewed from the X direction can be U-shaped. One end of the reinforcing portion 70 in the Y direction is connected to one second portion 62. The other end of the reinforcing portion 70 in the Y direction is connected to the other second portion 62. The ends of the reinforcing portion 70 can be connected, for example, by welding, brazing, or using fasteners such as screws to the second portion 62.

[0060] The reinforcing portion 70 can be formed from a metal such as stainless steel or an aluminum alloy. The reinforcing portion 70 can be formed by plastic deformation processes such as bending or pressing, or by drawing.

[0061] The thickness of the reinforcing portion 70 can be, for example, 0.3 mm or more and 2.0 mm or less. The Z-direction dimension L2 of the reinforcing portion 70 can be, for example, 30 mm or more and 80 mm or less. The X-direction dimension of the reinforcing portion 70 can be, for example, the same as the X-direction dimension of the base portion 60. In addition, multiple reinforcing portions 70 can be provided. That is, at least one reinforcing portion 70 can be provided. When multiple reinforcing portions 70 are provided, the multiple reinforcing portions 70 can be arranged in the X-direction with a predetermined interval between them.

[0062] If the reinforcing portion 70 extending in the Z direction is connected to the base portion 60, the bending rigidity can be increased. Therefore, even if the dimension W1 in the Y direction and the dimension L1 in the Z direction of the base portion 60 are reduced, warping of the heater 50 can be suppressed. Furthermore, the base portion 60 (first portion 61) having a convex curved surface (outer surface 61a) can be given the function of a stay. Therefore, the heater 50 can be used as is in the fixing portion 200a described later, and the stay can be omitted. If the stay can be omitted, the configuration of the fixing portion 200a can be simplified.

[0063] As described above, with the heater 50 according to this embodiment, even if the base portion 60 is made of metal, warping of the heater 50 can be suppressed, and the structure of the fixing portion 200a can be simplified.

[0064] (Image forming apparatus) In one embodiment of the present invention, an image forming apparatus 100 equipped with a heater 1 can be provided. The above-described heater 1 and its variations (for example, the heater 50 described above) can all be applied to the image forming apparatus 100.

[0065] Furthermore, in the following explanation, we will describe the case where the image forming apparatus 100 is a copier as an example. However, the image forming apparatus 100 is not limited to a copier; it can be any apparatus that has a fuser unit (heater) for fixing toner. For example, the image forming apparatus 100 can be a printer or the like.

[0066] Figure 5 is a schematic diagram illustrating the image forming apparatus 100 according to this embodiment. Figure 6 is a schematic diagram illustrating the fixing section 200. As shown in Figure 5, the image forming apparatus 100 includes, for example, a frame 110, an illumination unit 120, an imaging element 130, a photosensitive drum 140, a charging unit 150, a discharge unit 151, a developing unit 160, a cleaner 170, a storage unit 180, a transport unit 190, a fixing unit 200, and a controller 210.

[0067] The frame 110 is box-shaped and houses the illumination unit 120, the imaging element 130, the photosensitive drum 140, the charging unit 150, the developing unit 160, the cleaner 170, part of the storage unit 180, the transport unit 190, the fixing unit 200, and the controller 210 inside. A window 111 made of a light-transmitting material such as glass can be provided on the top surface of the frame 110. The original document 500 to be copied is placed on top of the window 111. A movable part for moving the position of the original document 500 can also be provided.

[0068] The lighting unit 120 is provided near the window 111. The lighting unit 120 includes, for example, a light source 121 such as a lamp, and a reflector 122. The imaging element 130 is located near the window 111. The photosensitive drum 140 is located below the illumination unit 120 and the imaging element 130. The photosensitive drum 140 is rotatably mounted. The surface of the photosensitive drum 140 is provided with, for example, a zinc oxide photosensitive layer or an organic semiconductor photosensitive layer. The charging unit 150, the discharge unit 151, the developing unit 160, and the cleaner 170 are located around the photosensitive drum 140.

[0069] The storage unit 180 includes, for example, a cassette 181 and a tray 182. The cassette 181 is detachably attached to one side of the frame 110. The tray 182 is located on the side of the frame 110 opposite to the side to which the cassette 181 is attached. The cassette 181 holds paper 510 (for example, blank paper) before copying. The tray 182 holds paper 511 on which the copied image 511a has been fixed.

[0070] The transport unit 190 is located below the photosensitive drum 140. The transport unit 190 transports the paper 510 between the cassette 181 and the tray 182. The transport unit 190 includes, for example, a guide 191 that supports the paper 510 being transported, and transport rollers 192 to 194 that transport the paper 510. The transport unit 190 may also be equipped with a motor to rotate the transport rollers 192 to 194.

[0071] The fixing unit 200 is located downstream of the photosensitive drum 140 (on the tray 182 side). As shown in Figure 6, the fixing unit 200 includes, for example, a heater 1, a film belt 202, and a pressure roller 203.

[0072] The heater 1 is installed so that the side with the protective section 40 faces the pressure roller 203. Generally, the fixing section is provided with a heater having a flat base, a stay to which the flat heater is attached, a film belt, and a pressure roller. As described above, with the heater 1 according to this embodiment, the base 10, which has a curved shape in the thickness direction, can be given the function of a stay. Therefore, the stay can be omitted, and the configuration of the fixing section 200 can be simplified.

[0073] The film belt 202 covers the heater 1. The film belt 202 contains a heat-resistant resin, such as polyimide.

[0074] The pressure roller 203 is positioned opposite the heater 1. The pressure roller 203 includes, for example, a core metal 203a, a drive shaft 203b, and an elastic portion 203c. The drive shaft 203b protrudes from the end of the core metal 203a and is connected to a drive device such as a motor. The elastic portion 203c is provided on the outer surface of the core metal 203a. The elastic portion 203c is formed from a heat-resistant elastic material. The elastic portion 203c may include, for example, silicone resin.

[0075] The controller 210 is located inside the frame 110. The controller 210 includes, for example, a processing unit such as a CPU (Central Processing Unit) and a storage unit that stores a control program. The processing unit controls the operation of each element provided in the image forming apparatus 100 based on the control program stored in the storage unit. The controller 210 may also include an operation unit for the user to input copying conditions, a display unit to display the operating status and error indications, etc. Since known techniques can be applied to the control of each element provided in the image forming apparatus 100, a detailed explanation will be omitted.

[0076] Figure 7 is a schematic diagram illustrating a fixing section 200a according to another embodiment. As shown in Figure 7, the fixing unit 200a includes, for example, a heater 50, a film belt 202, and a pressure roller 203.

[0077] The heater 50 is mounted so that the side with the protective part 40 faces the pressure roller 203. As described above, in the heater 50 according to this embodiment, the base part 60 (first part 61) having a convex curved surface (outer surface 61a) can be given the function of a stay. Therefore, a stay can be omitted, and the configuration of the fixing part 200a can be simplified.

[0078] Although several embodiments of the present invention have been illustrated above, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents. Furthermore, the embodiments described above can be implemented in combination with each other.

[0079] The following are additional notes regarding the embodiments described above.

[0080] (Note 1) A heater provided in the fixing section of an image forming apparatus, It has a plate-like shape, extends in a first direction, has one surface that is a convex curved surface, has a recess that opens into the convex curved surface and extends in the first direction, and has a base made of metal; An insulating layer provided on the bottom surface of the recess; A heating element provided on the insulating layer and extending in the first direction; A protective part covering the aforementioned heating element; A heater equipped with [a certain feature].

[0081] (Note 2) The base portion has a curved shape in the thickness direction, The heater according to Appendix 1, wherein the recess opens to the curved outer surface which is the convex curved surface of the base.

[0082] (Note 3) It further comprises a reinforcing portion that is plate-shaped and curved in the thickness direction, The base comprises: a first portion having the convex curved surface; and a pair of second portions provided on the periphery of the surface of the first portion facing the convex curved surface, projecting in a second direction intersecting the first direction; The recess opens to the convex curved surface of the first portion, The heater according to Appendix 1, wherein one end of the reinforcing portion is connected to one of the second portions, and the other end of the reinforcing portion is connected to the other second portion.

[0083] (Note 4) The heater according to any one of the appendices 1 to 3, wherein the radius of curvature of the convex curved surface in the vicinity of the recess is 0.1 mm or more.

[0084] (Note 5) An image forming apparatus comprising a fixing unit having a heater described in any one of the appendices 1 to 4; and a film belt covering the heater. [Explanation of Symbols]

[0085] 1 Heater, 10 Base, 10a Outer surface, 10a1 Recess, 11 Insulating layer, 20 Heating part, 21 Heating element, 22 Heating element, 40 Protective part, 50 Heater, 60 Base, 61 First part, 61a Outer surface, 62 Second part, 70 Reinforcement part, 100 Image forming apparatus, 200 Fixing part, 200a Fixing part

Images