Heater, and image forming apparatus

Abstract

To provide a heater that can reduce a manufacturing cost, and can prevent variations in the temperature in a plane of the heater, and an image forming apparatus.SOLUTION: A heater 1 comprises: a substrate 10 that exhibits a plate shape and extends in a first direction; a first heating element 21 that is provided on a side of one face of the substrate, and extends in the first direction; first wiring that is provided on the side of one face of the substrate, and is provided overlapping an end in the first direction of the first heating element; and a second heating element 22 that is provided on the side of one face of the substrate, and separate from the first heating element in a second direction orthogonal to the first direction. In the second direction, a first portion where the first heating element and the first wiring overlap each other, is adjacent to a second portion where the second heating element and second wiring overlap each other, and in the first direction, the first portion is separate from the second portion. In the second direction, the first portion faces the second heating element. In the first direction, the first heating element and the second heating element are not in the inclusion relation with each other.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] An embodiment of the present invention relates to a heater and an image forming apparatus. [Background technology]

[0002] For example, image forming devices such as copiers and printers are provided with heaters for fixing toner. In general, such heaters include a long substrate and a heating element that is provided on one surface of the substrate and extends in the longitudinal direction of the substrate.

[0003] In this case, it may be necessary to heat objects of different sizes (e.g., paper) with one heater. For this reason, a heater has been proposed in which heating elements of different lengths are arranged in the short direction of the substrate, and a heating element having an appropriate length is selected and used according to the size of the object to be heated. However, since the material of the heating element is expensive, there is a problem that the manufacturing cost of the heater increases when heating elements of different lengths are provided according to the size of the object to be heated.

[0004] For this reason, a heater has been proposed in which heating elements of different lengths are arranged side by side in the short direction of the substrate, and the ends of the heating elements of different lengths are arranged at the same position in the long direction of the substrate. In this way, heating elements of different lengths can be combined and used according to the size of the object to be heated. Therefore, compared to simply arranging heating elements of different lengths side by side, the total length of the heating elements, and therefore the amount of material for the heating elements, can be reduced. If the amount of material for the heating elements can be reduced, the manufacturing cost of the heater can be reduced.

[0005] However, simply combining heating elements of different lengths gives rise to a new problem of temperature variation across the surface of the heater. Therefore, there has been a demand for development of a technique that can reduce manufacturing costs and suppress temperature variations within the surface of the heater. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2020-115185 A Summary of the Invention [Problem to be solved by the invention]

[0007] An object of the present invention is to provide a heater and an image forming apparatus that can reduce manufacturing costs and suppress temperature variations within the surface of the heater. [Means for solving the problem]

[0008] The heater according to the embodiment includes a plate-shaped substrate extending in a first direction; a first heating element provided on one surface of the substrate and extending in the first direction; a first wiring provided on the one surface of the substrate and overlapping an end of the first heating element in the first direction; a second heating element provided on the one surface of the substrate in a second direction perpendicular to the first direction and spaced apart from the first heating element and extending in the first direction; and a second wiring provided on the one surface of the substrate and overlapping an end of the second heating element in the first direction. In the second direction, a first portion where the first heating element and the first wiring overlap is adjacent to a second portion where the second heating element and the second wiring overlap. In the first direction, the first portion is spaced apart from the second portion. The first portion faces the second heating element in the second direction. The first heating element and the second heating element do not have an inclusive relationship with each other in the first direction. Effect of the Invention

[0009] According to the embodiments of the present invention, it is possible to provide a heater and an image forming apparatus that can reduce manufacturing costs and suppress temperature variations within the surface of the heater. [Brief description of the drawings]

[0010] [Figure 1] FIG. 2 is a schematic front view illustrating the heater according to the present embodiment. [Diagram 2] FIG. 4 is a schematic rear view illustrating the heater. [Diagram 3] 2 is a schematic cross-sectional view of the heater in the direction of line AA in FIG. 1. [Figure 4] FIG. 11 is a schematic front view illustrating a heater according to a comparative example. [Diagram 5] 13 is a schematic front view illustrating a heater according to another comparative example. FIG. [Figure 6] 13 is a schematic front view illustrating a heater according to another comparative example. FIG. [Figure 7] 4(a) and 4(b) are schematic cross-sectional views of the vicinity of an end portion of a heating element. [Figure 8] 10A and 10B are schematic plan views illustrating the arrangement of portions where heating elements and wiring overlap. [Figure 9] 13 is a graph illustrating the relationship between the distance and the temperature of the portion where the heating element and the wiring overlap. [Figure 10] 10A to 10C are schematic plan views illustrating the end shapes of a heating element according to another embodiment. [Figure 11] 1 is a schematic diagram illustrating an image forming apparatus according to an embodiment of the present invention; [Figure 12] 3A and 3B are schematic diagrams for illustrating a fixing unit. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment will be illustrated with reference to the drawings. In each drawing, the same components are given the same reference numerals, and detailed description is omitted as appropriate. In each drawing, arrows X, Y, and Z represent three mutually orthogonal directions. For example, the longitudinal direction (e.g., length direction) of the substrate is the X direction (corresponding to an example of a first direction), the lateral direction (e.g., width direction) of the substrate is the Y direction (corresponding to an example of a second direction), and the direction perpendicular to the surface of the substrate (e.g., thickness direction) is the Z direction.

[0012] (heater) FIG. 1 is a schematic front view illustrating a heater 1 according to the present embodiment. FIG. 1 is a view of the heater 1 as seen from the side where the heat generating portion 20 is provided. FIG. 2 is a schematic rear view illustrating the heater 1. As shown in FIG. FIG. 2 is a view of the heater 1 as viewed from the side where the warp mitigating portion 50 is provided (the side opposite to the side where the heat generating portion 20 is provided). FIG. 3 is a schematic cross-sectional view of the heater 1 in FIG. 1 taken along the line AA. As shown in FIGS. 1 to 3, the heater 1 includes a substrate 10, an insulating layer 11, a heat generating portion 20, a wiring portion 30, a protective portion 40, and a warpage mitigating portion 50, for example.

[0013] The substrate 10 is plate-like and has a surface 10a and a surface 10b opposite to the surface 10a. The substrate 10 extends in the X direction. The shape of the substrate 10 as viewed from the Z direction is, for example, a long rectangular shape. The thickness of the substrate 10 is, for example, about 0.5 mm to 1.0 mm. The dimensions of the substrate 10 in the X direction and the dimensions of the substrate 10 in the Y direction can be appropriately changed depending on the size of the object to be heated (for example, paper) and the like.

[0014] The substrate 10 is made of a material that is heat resistant and has high thermal conductivity. The substrate 10 can be made of a metal such as stainless steel or an aluminum alloy. The substrate 10 can also be made of ceramics such as aluminum oxide or aluminum nitride, crystallized glass (glass ceramics), or the like.

[0015] In this case, the thermal conductivity of metal is higher than that of inorganic materials such as ceramics. Therefore, if the substrate 10 is made of a metal, it is possible to reduce the temperature variation within the surface of the heater 1. In addition, it is possible to improve the rigidity of the substrate 10 and reduce the manufacturing cost of the substrate 10. On the other hand, if the substrate 10 is made of an inorganic material such as ceramics, the insulating layer 11 described below can be omitted. This makes it possible to simplify the manufacturing process of the heater 1 and reduce the manufacturing cost of the heater 1. The material of the substrate 10 can be appropriately selected depending on the temperature variation, rigidity, manufacturing costs, etc. required for the heater 1. However, in order to reduce the temperature variation within the surface of the heater 1, it is preferable that the thermal conductivity of the material of the substrate 10 is 10 [W / (m K)] or more and 250 [W / (m K)] or less.

[0016] The insulating layer 11 is provided on the surface 10a of the substrate 10 on which the heat generating portion 20 is provided. The insulating layer 11 covers the area of ​​the surface 10a of the substrate 10 on which the heat generating portion 20 and the wiring portion 30 are provided. The insulating layer 11 insulates between the substrate 10, which is made of metal, and the heat generating portion 20 and the wiring portion 30. For this reason, the insulating layer 11 is formed of a material having heat resistance and insulating properties. The insulating layer 11 can be formed of an inorganic material such as ceramics or glass material. The insulating layer 11 can be formed, for example, by applying a paste-like material onto the surface 10a of the substrate 10 using a screen printing method or the like, and curing the material using a baking method or the like.

[0017] The heat generating section 20 converts the applied power into heat (Joule heat). The heat generating section 20 is provided on the surface 10a side of the substrate 10. The heat generating section 20 is provided, for example, on the insulating layer 11. When the substrate 10 is made of an insulating material such as ceramics, the heat generating section 20 can be provided on the surface 10a of the substrate 10.

[0018] Heat generating section 20 has, for example, a heat generating element 21 (corresponding to an example of a first heat generating element) and a heat generating element 22 (corresponding to an example of a second heat generating element). Heating element 21 and heating element 22 extend, for example, in the X direction. Heating element 22 is provided at a distance from heating element 21 in the Y direction. For example, two heating elements 22 can be provided for one heating element 21. In the X direction, each of the two heating elements 22 is provided in a region between the end of heating element 21 and the end of substrate 10. For example, the center of heating element 21 is located on straight line 1a. For example, the two heating elements 22 can be provided at positions that are linearly symmetrical with respect to straight line 1a.

[0019] It is also possible to provide one heating element 22 for one heating element 21. However, if two heating elements 22 are provided for one heating element 21, the arrangement of heating elements 21 and 22 can be as described above. If the arrangement of heating elements 21 and 22 is as described above, the heating object can be heated approximately uniformly even if the dimension of the heating object in the direction perpendicular to the transport direction changes. In the above, two types of heating elements are arranged in the Y direction, but three or more types of heating elements can be arranged in the Y direction. However, if the number of heating elements arranged in the Y direction increases, the dimension of the substrate 10 in the Y direction, and therefore the dimension of the heater 1, increases. The arrangement of the heating elements 21 and 22 in the X direction will be described in detail later.

[0020] In the X direction, the dimension of heating element 21 may be the same as or different from the dimension of heating element 22. In Fig. 1, the case where the dimension of heating element 21 in the X direction is longer than the dimension of heating element 22 is exemplified, but the dimension of heating element 21 may be shorter than the dimension of heating element 22. The dimensions of heating element 21 and heating element 22 in the X direction can be appropriately changed depending on the range of dimensions of the object to be heated that is required to be accommodated.

[0021] The heat generation amount per unit length of the heating element 22 can be the same as or different from the heat generation amount per unit length of the heating element 21. For example, if the resistance value per unit length of the heating element 22 is the same as the resistance value per unit length of the heating element 21, the heat generation amount per unit length of the heating element 22 can be the same as the heat generation amount per unit length of the heating element 21. For example, if the dimensions in the Y direction, the dimensions in the Z direction, and the material of the heating element 22 are the same as the dimensions in the Y direction, the dimensions in the Z direction, and the material of the heating element 22, the resistance value per unit length, and the heat generation amount per unit length can be the same. Note that in order to make the resistance value per unit length, and thus the heat generation amount per unit length, different, at least one of the dimensions in the Y direction, the dimensions in the Z direction, and the material may be made different.

[0022] Furthermore, the resistance value per unit length of at least one of the heating elements 21 and 22 can be approximately constant or can be varied. To make the resistance value per unit length of the heating element approximately constant, the Y-direction dimension, Z-direction dimension, and material of the heating element should be approximately constant. To change the resistance value per unit length of the heating element, at least one of the Y-direction dimension, Z-direction dimension, and material of the heating element should be changed.

[0023] Heating element 21 and heating element 22 can be formed using, for example, ruthenium oxide (RuO2), a silver-palladium (Ag-Pd) alloy, etc. Heating element 21 and heating element 22 can be formed, for example, by applying a paste-like material onto insulating layer 11 using a screen printing method or the like, and curing it using a baking method or the like.

[0024] The wiring portion 30 is provided on the surface 10a side of the substrate 10. The wiring portion 30 is provided on the insulating layer 11, for example. The wiring section 30 has, for example, a terminal 31, a terminal 32, a terminal 33, a wiring 34 (corresponding to an example of a first wiring), a wiring 35 (corresponding to an example of the first wiring), a wiring 36, a wiring 37 (corresponding to an example of a second wiring), and a wiring 38.

[0025] The terminal 31 and the terminal 32 are provided, for example, in the vicinity of one end of the substrate 10 in the X direction. For example, the terminal 32 is provided spaced apart from the terminal 31 in the X direction. The terminal 33 is provided, for example, near the other end of the substrate 10 in the X direction. Terminals 31, 32, and 33 are electrically connected to, for example, a controller 210 of image forming apparatus 100 described later via connectors, wiring, and the like. For example, by applying power to terminals 31 and 32, power can be applied to heating element 21 and two heating elements 22. Therefore, a heating object having a long dimension in the X direction can be heated. For example, by applying power to terminals 31 and 33, power can be applied to heating element 21 and not to two heating elements 22. Therefore, power consumption can be reduced when heating a heating object having a short dimension in the X direction.

[0026] The wiring 34 extends in the X direction. The wiring 34 is electrically connected to the terminal 31 and one end of the heating element 21. In this case, the wiring 34 and the heating element 21 can be electrically connected by overlapping the vicinity of the end of the wiring 34 and the vicinity of the end of the heating element 21 in the Z direction. As described later, the wiring 34 and the terminal 31 can be formed integrally.

[0027] The wiring 35 extends in the X direction. The wiring 35 is electrically connected to the terminal 33 and the other end of the heating element 21. In this case, the wiring 35 and the heating element 21 can be electrically connected by overlapping the vicinity of the end of the wiring 35 and the vicinity of the end of the heating element 21 in the Z direction. As described later, the wiring 35 and the terminal 33 can be formed integrally.

[0028] The wiring 36 extends in the X direction. The wiring 36 is electrically connected to the terminal 33 and one end of the heating element 22 provided on the side where the terminal 33 is provided. In this case, the wiring 36 and the heating element 22 can be electrically connected by overlapping the vicinity of the end of the wiring 36 with the vicinity of the end of the heating element 22 in the Z direction. As described later, the wiring 36 and the terminal 33 can be formed integrally.

[0029] The wiring 37 extends in the X direction. The wiring 37 is provided between the heating elements 22. The wiring 37 is electrically connected to the heating elements 22. In this case, the wiring 37 and the heating elements 22 can be electrically connected by overlapping the vicinity of an end of the wiring 37 and the vicinity of an end of the heating elements 22 in the Z direction.

[0030] The wiring 38 extends in the X direction. The wiring 38 is electrically connected to the terminal 32 and one end of the heating element 22 provided on the side where the terminal 32 is provided. In this case, the wiring 38 and the heating element 22 can be electrically connected by overlapping the vicinity of the end of the wiring 38 and the vicinity of the end of the heating element 22 in the Z direction. As described later, the wiring 38 and the terminal 32 can be formed integrally.

[0031] The wiring portion 30 (terminals 31 to 33 and wires 34 to 38) are formed using a material containing, for example, silver, copper, etc. For example, the wiring portion 30 can be formed by applying a paste-like material onto the insulating layer 11 using a screen printing method or the like, and curing it using a baking method or the like.

[0032] The protective portion 40 is provided on the insulating layer 11, and covers the heat generating portion 20 (heat generating element 21 and heat generating element 22) and a part of the wiring portion 30 (wires 34 to 38). In this case, the terminals 31, 32, and 33 of the wiring portion 30 are exposed from the protective portion 40.

[0033] The protective section 40 extends in the X direction. The protective section 40 has, for example, a function of insulating the heat generating section 20 and a part of the wiring section 30, a function of transmitting heat generated in the heat generating section 20 to the outside, and a function of protecting the heat generating section 20 and a part of the wiring section 30 from external forces, corrosive gases, and the like. The protective section 40 is formed from a material that has heat resistance and insulation properties, and has high chemical stability and thermal conductivity. The protective section 40 is formed from an inorganic material such as ceramics or glass. In this case, the protective section 40 can also be formed using glass to which a filler containing a material with high thermal conductivity such as aluminum oxide is added. The thermal conductivity of the glass to which the filler is added can be, for example, 2 [W / (m·K)] or more.

[0034] The heater 1 may further be provided with a detection unit that detects the temperature of the heat generating unit 20 and the temperature of the substrate 10. The detection unit may be, for example, a thermistor. The detection unit may be provided on at least one of the side of the substrate 10 on which the heat generating unit 20 is provided and the side of the substrate 10 opposite to the side on which the heat generating unit 20 is provided. For example, the detection unit and the wiring and terminals electrically connected to the detection unit may be provided on the insulating layer 11. In this case, the detection unit and the wiring may be covered by the protective unit 40. The terminals electrically connected to the detection unit may be exposed from the protective unit 40.

[0035] Here, when the heater 1 is used, the heat generating portion 20 generates heat, and the substrate 10, the insulating layer 11, and the protective portion 40 are heated. When the heat generating portion 20, the wiring portion 30, the insulating layer 11, and the protective portion 40 are baked during the manufacture of the heater 1, the substrate 10, the insulating layer 11, and the protective portion 40 are heated. In addition, the material of the insulating layer 11 and the protective portion 40 is different from the material of the substrate 10. Therefore, when the heater 1 is used or manufactured, thermal stress occurs due to the difference in linear expansion coefficient. When thermal stress occurs on one surface side (for example, the surface 10a side) of the substrate 10, the heater 1 may warp. In addition, when the length of the substrate 10 in the short direction (for example, the Y direction) is short, when the length of the substrate 10 in the long direction (for example, the X direction) is long, or when the thickness of the substrate 10 is thin, the heater 1 is likely to warp. In this case, if the heater 1 is significantly warped, the distance between the heater 1 and the object to be heated may vary, resulting in uneven heating of the object to be heated.

[0036] 2 and 3, the heater 1 is provided with a warpage mitigating portion 50. The warpage mitigating portion 50 is provided on the surface 10b of the substrate 10, which faces the surface 10a. If the warpage mitigating portion 50 is provided on the surface 10b of the substrate 10, the thermal stress generated on the surface 10a side of the substrate 10 can be offset by the thermal stress generated on the surface 10b side of the substrate 10. Therefore, it is possible to suppress the occurrence of warpage in the heater 1 when the heater 1 is used or when the heater 1 is manufactured.

[0037] It is possible to provide at least one warp mitigating portion 50. When providing a plurality of warp mitigating portions 50, for example, the plurality of warp mitigating portions 50 can be arranged side by side in the X direction. Note that one warp mitigating portion 50 illustrated in FIG. 2 is provided on the surface 10b of the substrate 10.

[0038] Furthermore, the dimension of the warp mitigating portion 50 in the Y direction may be the same as the dimension of the substrate 10 in the Y direction, or may be shorter than the dimension of the substrate 10. Note that the dimension of the warp mitigating portion 50 illustrated in FIG. 2 in the Y direction is shorter than the dimension of the substrate 10 in the Y direction. The material of the warp mitigating portion 50 can be, for example, an inorganic material such as ceramics or glass.

[0039] That is, the number, arrangement, and dimensions of the warp mitigation portions 50 can be appropriately changed depending on the warp generated in the heater 1. The number, arrangement, and dimensions of the warp mitigation portions 50 can be appropriately determined by, for example, conducting experiments or simulations. Furthermore, if the amount of warping that occurs is small, the warping mitigating portion 50 can be omitted.

[0040] Next, the arrangement of the heat generating element 21 and the heat generating element 22 in the X direction will be further described. First, a comparative example will be described. FIG. 4 is a schematic front view illustrating a heater 61 according to a comparative example. FIG. 4 corresponds to FIG. As shown in FIG. 4, a heater 61 according to the comparative example includes a substrate 10, an insulating layer 11, a heating element 23, a wiring portion 30, a protective portion 40, and a warpage mitigating portion 50. The heater 61 includes a substrate 10, an insulating layer 11, a heating element 23, a wiring portion 30, a protective portion 40, and a warpage mitigating portion 50.

[0041] Two heating elements 23 are provided at a predetermined interval in the Y direction. The two heating elements 23 extend in the X direction. The centers of the two heating elements 23 in the X direction are located on a straight line 61a. The dimension of the heating elements 23 in the X direction is longer than the dimension of the largest heating object. In this way, one type of heating element 23 can be used to heat heating objects of different sizes.

[0042] However, if one type of heating element 23 is used to heat objects of different sizes, the heating element 23 will be unnecessarily long when heating a small object. Materials for the heating element 23, such as ruthenium oxide (RuO2) and silver-palladium (Ag-Pd) alloy, are expensive. This causes a problem that the manufacturing cost of the heating element 23 is unnecessarily high. In addition, there is also a problem that power consumption is unnecessarily high when heating a small object.

[0043] FIG. 5 is a schematic front view illustrating a heater 62 according to another comparative example. FIG. 5 corresponds to FIG. As shown in FIG. 5, a heater 62 according to the comparative example includes a substrate 10, an insulating layer 11, a heating element 23, a heating element 24, a wiring portion 30, a protective portion 40, and a warpage mitigating portion 50. As shown in FIG.

[0044] Heating element 23 and heating element 24 are provided at a predetermined interval in the Y direction. The center of heating element 23 in the X direction is located on straight line 62a. The center of heating element 24 in the X direction is located on straight line 62a. The length of heating element 24 in the X direction is shorter than the length of heating element 23.

[0045] The dimension of heating element 23 in the X direction is longer than the dimension of the largest object to be heated, and the dimension of heating element 24 in the X direction is longer than the dimension of the smallest object to be heated.

[0046] Therefore, when the largest object to be heated is heated, power is applied to terminals 32 and 33 to cause heating element 23 to generate heat. When the smallest object to be heated is heated, power is applied to terminals 31 and 33 to cause heating element 24 to generate heat. In this way, it is possible to prevent unnecessary power consumption when heating a small object to be heated. However, since a long heating element 23 is provided, there is room for improvement in terms of reducing manufacturing costs.

[0047] FIG. 6 is a schematic front view illustrating a heater 63 according to another comparative example. FIG. 6 corresponds to FIG. As shown in FIG. 6, the heater 63 of the comparative example has a substrate 10, an insulating layer 11, a heating element 21, a heating element 22, a wiring portion 30, a protective portion 40, and a warpage mitigation portion 50, similar to the heater 1 of the present embodiment.

[0048] The center of the heat generating element 21 is located on the straight line 63a. The two heat generating elements 22 are provided at positions that are symmetrical with respect to the straight line 63a. In this case, in the Y direction, the end of the heating element 22 on the heating element 21 side is provided on an extension line of the end of the heating element 21. That is, in the Y direction, the end of the heating element 21 and the end of the heating element 22 on the heating element 21 side are in the same position. For example, the distance between the straight line 63a and the end of the heating element 21 is the same as the distance between the straight line 63a and the end of the heating element 22 on the straight line 63a side.

[0049] In addition, the dimension of the heating element 21 in the X direction is longer than the dimension of the smallest object to be heated. In the X direction, the distance between the ends of the heating elements 22 on the opposite side to the heating element 21 side is longer than the dimension of the largest object to be heated.

[0050] When the smallest sized object to be heated is to be heated, power is applied to terminals 31 and 33 to cause heating element 21 to generate heat. When heating the largest heating object, power is applied to terminals 31 and 32 to heat heating element 21 and two heating elements 22. In this case, as described above, the end of heating element 22 on the heating element 21 side is provided on an extension line of the end of heating element 21 in the Y direction, so heating element 21 and two heating elements 22 can be used as one continuous heating element.

[0051] In this way, the total length of the heating elements can be made shorter than in the case of two heating elements 23 or in the case of heating elements 23 and 24. This makes it possible to reduce the manufacturing cost of the heater.

[0052] However, it was found that doing so causes temperature variation within the surface of the heater 63. If the temperature varies within the surface of the heater 63, there is a risk that the temperature of the object to be heated will vary. As a result of investigation, the inventors of the present invention found that the reason for the temperature variation within the surface of the heater 63 is that the temperature in the vicinity of the ends of the heating elements 21, 22 is lower than the temperature in the central parts of the heating elements 21, 22.

[0053] 7(a) and (b) are schematic cross-sectional views of the vicinity of the ends of the heating elements 21 and 22. FIG. As described above, the heating elements 21, 22 and the wirings 34-38 can be formed using a screen printing method and a baking method. Fig. 7(a) shows a case where the wirings 34-38 are formed before the heating elements 21, 22. Fig. 7(b) shows a case where the heating elements 21, 22 are formed before the wirings 34-38. In the heater 63 illustrated in Fig. 6, the wirings 34-38 are formed before the heating elements 21, 22. Regardless of whether the heating elements 21, 22 or the wirings 34-38 are formed first, there will be portions near the ends of the heating elements 21, 22 that overlap with the wirings 34-38.

[0054] As described above, the wirings 34-38 contain low-resistance metals such as silver and copper. Therefore, in the portions of the heating elements 21 and 22 overlapping with the wirings 34-38, current mainly flows through the wirings 34-38, and current does not easily flow through the heating elements 21 and 22. Therefore, the amount of heat generated in the portions of the heating elements 21 and 22 overlapping with the wirings 34-38 is smaller than the amount of heat generated in the central portions of the heating elements 21 and 22. Furthermore, since low-resistance metals such as silver and copper have high thermal conductivity, heat near the ends of the heating elements 21 and 22 is easily released to the outside through the wirings 34-38. Therefore, the temperature near the ends of the heating elements 21 and 22 is lower than the temperature in the central portions of the heating elements 21 and 22.

[0055] When the heating element 21 and the two heating elements 22 are used as one heating element, if the overlapping portion between the heating element 21 and the wiring 34, 35 and the overlapping portion between the heating element 22 and the wiring 37 are continuous or overlapping in the X direction as shown in Fig. 6, a low temperature portion will be generated in one heating element. Therefore, there is a risk that the temperature will vary within the surface of the heater 63, causing the temperature of the heated object to vary.

[0056] Therefore, in the heater 1 according to the present embodiment, in the X direction, a portion 21a (corresponding to an example of a first portion) where the heating element 21 and the wirings 34 and 35 overlap is adjacent to a portion 22a (corresponding to an example of a second portion) where the heating element 22 and the wiring 37 overlap. In addition, in the X direction, the portion 21a is separated from the portion 22a, and in the Y direction, the portion 21a faces the heating element 22a. In addition, in the X direction, the heating element 21 and the heating element 22 are not in an inclusive relationship with each other. That is, in the Y direction, a part of the heating element 22 is provided at a position where it overlaps with the heating element 21, but the remaining part of the heating element 22 does not overlap with the heating element 21. In the Y direction, a part of the heating element 21 is provided at a position where it overlaps with the heating element 22, but the remaining part of the heating element 21 does not overlap with the heating element 22. For example, in the X direction, the center line of the heating element 22a is separated from the center line of the heating element 21a. FIG. 8 is a schematic plan view illustrating the arrangement of the portions where the heat generating elements and the wiring overlap. FIG. 8 is a schematic enlarged view of part B in FIG. Further, in FIG. 8, the portion where the heat generating element 21 and the wiring 34 overlap will be described, but the portion where the heat generating element 21 and the wiring 35 overlap is similar.

[0057] As shown in FIG. 8, in the X direction, a portion 21a where the heat generating element 21 and the wiring 34 overlap is separated from a portion 22a where the heat generating element 22 and the wiring 37 overlap. In this way, the high-temperature heating element 22 can be adjacent to the vicinity of the low-temperature portion 21a in the Y direction. Therefore, heat from the heating element 22 can be transferred to the vicinity of the portion 21a. Also, the high-temperature heating element 21 can be adjacent to the vicinity of the low-temperature portion 22a in the Y direction. Therefore, heat from the heating element 21 can be transferred to the vicinity of the portion 22a. As a result, the temperature variation within the surface of the heater 1 can be suppressed.

[0058] The temperature in the vicinity of the end of the heating element 22 opposite the heating element 21 side is also lower than the temperature of the central part of the heating element 22. However, the vicinity of the end of the heating element 22 opposite the heating element 21 side can be provided outside the object to be heated. Therefore, even if the temperature in the vicinity of the end of the heating element 22 opposite the heating element 21 side is lower than the temperature of the central part of the heating element 22, it is possible to suppress the occurrence of variations in the temperature of the object to be heated.

[0059] Also, similar to the heater 63 described above, the total length of the heating elements can be made shorter than in the case of two heating elements 23 or in the case of heating elements 23 and 24. This allows for a reduction in the manufacturing cost of the heater.

[0060] Next, the arrangement of the overlapping portions of the heating elements and wiring will be further described. 8, in the X direction, the distance between a portion 21a where the heat generating element 21 and the wiring 34 overlap and a portion 22a where the heat generating element 22 and the wiring 37 overlap is defined as L1 (mm). In the Y direction, the distance between the heat generating element 21 and the heat generating element 22 is defined as L2 (mm).

[0061] FIG. 9 is a graph for illustrating the relationship between the temperature of the portion 21a and the temperature of the portion 22a and the distance L1 (mm) and the distance L2 (mm). 9 is a case where the temperature of portion 21a and the temperature of portion 22a are 95% of the temperature of the central portion of heating element 21 or heating element 22. C2 is a case where the temperature of portion 21a and the temperature of portion 22a are the temperature of the central portion of heating element 21 or heating element 22. 9, if "L1 (mm) = 2.35 × L2 (mm)", the temperature of portion 21a and the temperature of portion 22a can be set to 95% of the temperature of the central portion of heating element 21 or heating element 22. In other words, for practical purposes, heating element 21 and heating element 22 can be regarded as one heating element.

[0062] Furthermore, if "L1 (mm) = 2.35 × L2 (mm) + 9.15 (mm)", the temperature of portion 21a and the temperature of portion 22a can be made to be the temperature of the central portion of heating element 21 or heating element 22. In other words, heating element 21 and heating element 22 can be regarded as one heating element. Therefore, if "2.35×L2 (mm)≦L1 (mm)≦2.35×L2 (mm)+9.15 (mm)" is satisfied, the temperature variation within the surface of the heater 1 can be suppressed.

[0063] FIG. 10 is a schematic plan view illustrating the shape of an end portion of a heating element according to another embodiment. In addition, in FIG. 10, the portion where the heat generating element 21 (heat generating element 22) and the wiring 34 (wiring 37) overlap will be described, but the portion where the heat generating element 21 and the wiring 35 overlap is similar.

[0064] As shown in Fig. 10, the dimension (width dimension) of the heating element 21 (heating element 22) in the Y direction may differ from the dimension (width dimension) of the wiring 34 (wiring 37). In such a case, in the portion 21a (portion 22a), the dimension in the Y direction near the end of the heating element 21 (heating element 22) can be made to change gradually or stepwise toward the end of the heating element 21 (heating element 22). In the example shown in Fig. 10, the dimension in the vicinity of the end of the heating element 21 (heating element 22) gradually decreases toward the end of the heating element 21 (heating element 22). In this way, the temperature of the portion 21a (portion 22a) can be increased.

[0065] In FIG. 10, the dimensions near the ends of the heating element 21 (heating element 22) are changed over the entire area of ​​portion 21a (portion 22a), but it is sufficient to change the dimensions near the ends of the heating element 21 (heating element 22) over at least a portion of the area of ​​portion 21a (portion 22a).

[0066] (Image forming device) In one embodiment of the present invention, it is possible to provide an image forming apparatus 100 equipped with a heater 1. The above description of the heater 1 and modified versions of the heater 1 (for example, versions in which a person skilled in the art has appropriately added or removed components or modified the design and which have the features of the present invention) can all be applied to the image forming apparatus 100.

[0067] In the following, as an example, the image forming apparatus 100 will be described as a copier. However, the image forming apparatus 100 is not limited to a copier, and may be any apparatus provided with a heater for fixing toner. For example, the image forming apparatus 100 may be a printer or a rewritable card reader / writer.

[0068] FIG. 11 is a schematic diagram illustrating an image forming apparatus 100 according to the present embodiment. FIG. 12 is a schematic diagram illustrating the fixing unit 200. As shown in FIG. As shown in FIG. 11, the image forming apparatus 100 includes, for example, a frame 110, an illumination section 120, an imaging element 130, a photosensitive drum 140, a charging section 150, a discharging section 151, a developing section 160, a cleaner 170, a storage section 180, a conveying section 190, a fixing section 200, and a controller 210.

[0069] The frame 110 is box-shaped and houses therein an illumination section 120, an imaging element 130, a photosensitive drum 140, a charging section 150, a developing section 160, a cleaner 170, part of a storage section 180, a transport section 190, a fixing section 200, and a controller 210. A window 111 made of a light-transmitting material such as glass may be provided on the upper surface of the frame 110. An original 500 to be copied is placed on the window 111. Also, a moving unit for moving the position of the original 500 may be provided.

[0070] The illumination unit 120 is provided near the window 111. The illumination unit 120 has a light source 121, such as a lamp, and a reflecting mirror 122, for example. The imaging element 130 is provided near the window 111 . The photosensitive drum 140 is provided below the illumination unit 120 and the imaging element 130. The photosensitive drum 140 is provided rotatably. On the surface of the photosensitive drum 140, for example, a zinc oxide photosensitive layer or an organic semiconductor photosensitive layer is provided. The charging unit 150 , the discharging unit 151 , the developing unit 160 , and the cleaner 170 are provided around the photosensitive drum 140 .

[0071] The storage section 180 has, 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 provided on the side of the frame 110 opposite to the side on which the cassette 181 is attached. The cassette 181 stores paper 510 (e.g., blank paper) before copying. The tray 182 stores paper 511 on which a copy image 511a is fixed.

[0072] The transport unit 190 is provided 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 has, for example, a guide 191 that supports the transported paper 510, and transport rollers 192-194 that transport the paper 510. The transport unit 190 can also be provided with a motor that rotates the transport rollers 192-194.

[0073] The fixing unit 200 is provided downstream of the photosensitive drum 140 (on the tray 182 side). As shown in FIG. 12, the fixing unit 200 includes, for example, a heater 1, a stay 201, a film belt 202, and a pressure roller 203. The heater 1 is attached to the stay 201 on the side of the conveyance line for the paper 510. The heater 1 can be embedded in the stay 201. In this case, the side of the heater 1 on which the protective part 40 is provided is exposed from the stay 201.

[0074] The film belt 202 covers the stay 201 on which the heater 1 is provided. The film belt 202 may contain, for example, a heat-resistant resin such as polyimide.

[0075] The pressure roller 203 is disposed so as to face the stay 201. The pressure roller 203 has, for example, a core metal 203a, a drive shaft 203b, and an elastic portion 203c. The drive shaft 203b protrudes from an end of the core metal 203a and is connected to a drive device such as a motor. The elastic portion 203c is disposed 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 contain, for example, a silicone resin.

[0076] Controller 210 is provided inside frame 110. Controller 210 has, for example, a calculation unit such as a CPU (Central Processing Unit) and a storage unit in which a control program is stored. The calculation unit controls the operation of each element provided in image forming apparatus 100 based on the control program stored in the storage unit. Controller 210 can also include an operation unit through which a user inputs copying conditions, a display unit that displays the operating state, an error display, and the like. In addition, since known techniques can be applied to the control of each element provided in the image forming apparatus 100, detailed description thereof will be omitted.

[0077] Although some embodiments of the present invention have been illustrated above, these embodiments are presented as examples 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, modifications, etc. can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are included in the scope of the invention and its equivalents described in the claims. In addition, the above-mentioned embodiments can be implemented in combination with each other.

[0078] Below, additional notes regarding the above-described embodiment are given.

[0079] (Appendix 1) A substrate having a plate shape and extending in a first direction; a first heating element provided on one surface side of the substrate and extending in the first direction; a first wiring provided on the one surface side of the substrate and overlapping an end portion of the first heating element in the first direction; a second heating element provided on the one surface side of the substrate in a second direction perpendicular to the first direction and spaced apart from the first heating element and extending in the first direction; a second wiring provided on the one surface side of the substrate and overlapping an end portion of the second heating element in the first direction; Equipped with In the second direction, a first portion where the first heating element and the first wiring overlap is adjacent to a second portion where the second heating element and the second wiring overlap; In the first direction, the first portion is spaced apart from the second portion; In the second direction, the first portion faces the second heating element, A heater in which the first heating element and the second heating element are not in an inclusive relationship with each other in the first direction.

[0080] (Appendix 2) A heater as described in Appendix 1, which satisfies the following formula when the distance between the first portion and the second portion in the first direction is L1 (mm) and the distance between the first heating element and the second heating element in the second direction is L2 (mm).

[0081] 2.35×L2(mm)≦L1(mm)≦2.35×L2(mm)+9.15(mm) (Appendix 3) The resistance value per unit length of the first heating element is approximately constant, 3. The heater according to claim 1, wherein the resistance value per unit length of the second heating element is approximately constant.

[0082] (Appendix 4) 3. The heater of claim 1, wherein in the first portion, a dimension in the second direction near the end of the first heating element changes gradually or in steps toward the end of the first heating element.

[0083] (Appendix 5) A heater as described in any one of appendix 1, 2, and 4, wherein in the second portion, a dimension in the second direction near the end of the second heating element changes gradually or in steps toward the end of the second heating element.

[0084] (Appendix 6) 6. The heater according to any one of claims 1 to 5, wherein the thermal conductivity of the material of the substrate is not less than 10 [W / (m·K)] and not more than 250 [W / (m·K)].

[0085] (Appendix 7) An image forming apparatus comprising the heater according to any one of claims 1 to 6. [Explanation of symbols]

[0086] 1 heater, 10 substrate, 10a surface, 10b surface, 11 insulating layer, 20 heat generating portion, 21 heat generating element, 21a portion, 22 heat generating element, 22a portion, 30 wiring portion, 34 to 38 wiring, 40 protection portion, 100 image forming apparatus, 200 fixing portion

Claims

1. A substrate having a plate shape and extending in a first direction; a first heating element provided on one surface side of the substrate and extending in the first direction; a first wiring provided on the one surface side of the substrate and overlapping an end portion of the first heating element in the first direction; a second heating element provided on the one surface side of the substrate in a second direction perpendicular to the first direction and spaced apart from the first heating element and extending in the first direction; a second wiring provided on the one surface side of the substrate and overlapping an end portion of the second heating element in the first direction; Equipped with In the second direction, a first portion where the first heating element and the first wiring overlap is adjacent to a second portion where the second heating element and the second wiring overlap; In the first direction, the first portion is spaced apart from the second portion; In the second direction, the first portion faces the second heating element, A heater in which the first heating element and the second heating element are not in an inclusive relationship with each other in the first direction.

2. 2. The heater of claim 1, wherein the following formula is satisfied when the distance between the first portion and the second portion in the first direction is L1 (mm) and the distance between the first heating element and the second heating element in the second direction is L2 (mm). 2.35×L2(mm)≦L1(mm)≦2.35×L2(mm)+9.15(mm)

3. The resistance value per unit length of the first heating element is approximately constant, 3. The heater according to claim 1, wherein the resistance value per unit length of the second heating element is approximately constant.

4. 3. The heater of claim 1, wherein the dimension of the first portion in the second direction near the end of the first heating element changes gradually or stepwise toward the end of the first heating element.

5. 3. The heater of claim 1, wherein in the second portion, a dimension in the second direction near the end of the second heating element changes gradually or in steps toward the end of the second heating element.

6. 3. The heater according to claim 1, wherein the material of the substrate has a thermal conductivity of 10 [W / (m·K)] or more and 250 [W / (m·K)] or less.

7. 2. An image forming apparatus comprising the heater according to claim 1.

Images