Heater and image forming apparatus

Abstract

To provide a heater which can switch a heating range according to the size of a heating object, can be miniaturized and can suppress the breakage of a substrate, and provide an image formation apparatus.SOLUTION: A heater according to the embodiment comprises: a substrate which includes metal and has a shape that extends in one direction; a first insulation part which is provided on a first surface of the substrate and has the insulation property; a first heating element which is provided on the first insulation part and extends along the longitudinal direction of the substrate; a first protection part which is provided on the first insulation part, extends along the longitudinal direction of the substrate and covers the first heating element; a second insulation part which is provided on the second surface opposed to the first surface of the substrate and has the insulation property; a second heating element which is provided on the second insulation part and extends along the longitudinal direction of the substrate; and a second protection part which is provided on the second insulation part, extends along the longitudinal direction of the substrate and covers the second heating element. The length of the second heating element is different from the length of the first heating element in the longitudinal direction of the substrate.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] Image forming devices such as copiers and printers are equipped with heaters for fixing toner. Heaters are also provided in print / erase devices installed in rewritable card readers / writers. Generally, such heaters have a long substrate, a heating element provided on one side of the substrate and extending in the longitudinal direction of the substrate, and a protective part that covers the heating element.

[0003] In recent years, there has been a demand for a single heater that can heat objects of different sizes, i.e., versatility for different sizes of objects to be heated. To this end, a heater has been proposed that provides multiple heating elements on one side of a long substrate and switches the heating range depending on the size of the object to be heated.

[0004] However, in such heaters, multiple heating elements are arranged in the short-side direction (width direction) of the long substrate, which increases the short-side dimension of the substrate, making it difficult to miniaturize the heater. Furthermore, since such heaters use substrates made of ceramics, when the heating range is changed depending on the size of the object to be heated, the temperature difference in the longitudinal direction of the long substrate becomes large, and the generated thermal stress can cause the substrate to crack. Therefore, there has been a demand for the development of a technology that can switch the heating range depending on the size of the object to be heated, and that can achieve miniaturization and suppress damage to the substrate. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-244867 Summary of the Invention [Problem to be solved by the invention]

[0006] The problem that the present invention aims to solve is to provide a heater and an image forming apparatus that can switch the heating range depending on the size of the object to be heated, and that can be made smaller and prevent damage to the substrate. [Means for solving the problem]

[0007] The heater according to the embodiment includes a substrate including a metal and having a shape extending in one direction; a first insulating portion provided on a first surface of the substrate and having insulating properties; and a heater provided on the first insulating portion and extending along the longitudinal direction of the substrate. Mino a first heating element; a pair of first wirings provided on the first insulating portion and electrically connected to opposite end portions of the first heating element; The first insulating portion is provided on the first insulating portion, and extends along the longitudinal direction of the substrate. the pair of first wirings; a first protective portion covering the a pair of first terminals provided on the first insulating portion and electrically connected to ends of the pair of first wirings opposite to the first heating element side; a second insulating portion provided on a second surface of the substrate opposite to the first surface and having insulating properties; and a second insulating portion provided on the second insulating portion and extending along the longitudinal direction of the substrate. Mino a second heating element; a pair of second wirings provided on the second insulating portion and electrically connected to opposite end portions of the second heating element; The second insulating portion is provided on the second insulating portion, and extends along the longitudinal direction of the substrate. and the pair of second wirings; a second protective portion covering the a pair of second terminals provided on the second insulating portion and electrically connected to ends of the pair of second wirings opposite to the second heating element side; In the longitudinal direction of the substrate, the length of the second heating element is different from the length of the first heating element. In the longitudinal direction of the substrate, the center of the second heating element is at the same position as the center of the first heating element. In the lateral direction of the substrate, the center of the first heating element and the center of the second heating element are at the center of the substrate. When viewed from a direction intersecting the first surface, the first wiring and the second wiring overlap, and the first terminal and the second terminal overlap. [Effects of the Invention]

[0008] According to an embodiment of the present invention, it is possible to provide a heater and an image forming apparatus that can switch the heating range depending on the size of the object to be heated, and that can be made smaller and prevent damage to the substrate. [Brief explanation of the drawings]

[0009] [Figure 1] 2 is a schematic diagram of the heater according to the present embodiment when viewed from one side in the Z direction. FIG. [Figure 2] FIG. 10 is a schematic diagram of the heater as viewed from the other side in the Z direction. [Figure 3] 2 is a schematic cross-sectional view of the heater in the direction of line AA in FIG. 1. [Figure 4] 1 is a schematic diagram illustrating an image forming apparatus according to an embodiment of the present invention; [Figure 5] FIG. 2 is a schematic diagram illustrating a fixing unit. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments will be illustrated with reference to the drawings. In each drawing, similar components are designated by the same reference numerals, and detailed descriptions thereof will be omitted where appropriate. In each drawing, arrows X, Y, and Z represent three mutually orthogonal directions. For example, the longitudinal direction of the substrate is the X direction, the short side direction (width direction) of the substrate is the Y direction, and the direction perpendicular to the surface of the substrate is the Z direction.

[0011] (heater) FIG. 1 is a schematic diagram of a heater 1 according to this embodiment when viewed from one side in the Z direction. FIG. 2 is a schematic diagram of the heater 1 as viewed from the other side in the Z direction. FIG. 3 is a schematic cross-sectional view of the heater 1 in FIG. 1 taken along the line AA. 1 to 3, the heater 1 includes, for example, a substrate 10, an insulating portion 21 (corresponding to an example of a first insulating portion), an insulating portion 22 (corresponding to an example of a second insulating portion), a heating element 31 (corresponding to an example of a first heating element), a heating element 32 (corresponding to an example of a second heating element), a wiring portion 41, a wiring portion 42, a protective portion 51 (corresponding to an example of a first protective film), and a protective portion 52 (corresponding to an example of a second protective film). The insulating portion 21, the heating element 31, the wiring portion 41, and the protective portion 51 are provided on one surface 10a of the substrate 10 in the Z direction. The insulating portion 22, the heating element 32, the wiring portion 42, and the protective portion 52 are provided on the other surface 10b of the substrate 10 in the Z direction.

[0012] The substrate 10 is plate-shaped and has a surface 10a (corresponding to an example of a first surface) and a surface 10b (corresponding to an example of a second surface) opposite to the surface 10a. The substrate 10 has a shape that extends in one direction (for example, the X direction). The planar shape of the substrate 10 is, for example, an elongated rectangle. The thickness of the substrate 10 is, for example, about 0.5 mm to 1.0 mm. The width dimension W (short-side dimension; dimension in the Y direction) of the substrate 10 is, for example, about 5 mm to 15 mm. The length L (longitudinal dimension; dimension in the X direction) of the substrate 10 can be changed as appropriate depending on the size of the object to be heated (for example, paper).

[0013] The substrate 10 is made of a heat-resistant material with high thermal conductivity. Generally, the substrate 10 is made of ceramics such as aluminum oxide, but the heater 1 according to this embodiment is provided with a substrate 10 containing a metal. The metal can be, for example, stainless steel, an aluminum alloy, or the like.

[0014] As shown in FIGS. 1 and 3, the insulating portion 21 has insulating properties and is provided on the surface 10a of the substrate 10. The insulating portion 21 can be provided, for example, so as to cover the surface 10a of the substrate 10. The insulating portion 21 is provided to insulate the metal-containing substrate 10 from the heating element 31 and the wiring portion 41. Therefore, the insulating portion 21 is provided between the substrate 10 and the heating element 31 and the wiring portion 41. The insulating portion 21 can be formed from an inorganic material such as ceramics or glass. The insulating portion 21 can be formed, for example, by thermal spraying or firing.

[0015] Heat generating element 31 converts the applied power into heat (Joule heat) and is provided on insulating section 21 (on the surface of insulating section 21 opposite to the substrate 10 side). The heating element 31 extends, for example, along the longitudinal direction (X direction) of the substrate 10. The heating element 31 can be formed using, for example, ruthenium oxide (RuO2), a silver-palladium (Ag-Pd) alloy, etc. The heating element 31 can be formed, for example, by applying a paste-like material onto the insulating part 21 using a screen printing method or the like, and then curing it using a baking method or the like.

[0016] The wiring portion 41 is provided, for example, on the surface of the insulating portion 21 on which the heating element 31 is provided. The wiring portion 41 has, for example, a terminal 41a and a wire 41b. For example, a pair of terminals 41a may be provided. Each of the pair of terminals 41a may be provided near the end portions of the substrate 10 on both sides in the X direction. The pair of terminals 41a may be electrically connected to a power supply, a control circuit, or the like via a connector, wiring, or the like.

[0017] For example, a pair of wires 41b may be provided. Each of the pair of wires 41b electrically connects the terminal 41a and the heating element 31. One end of the wire 41b is electrically connected to the terminal 41a. The other end of the wire 41b is electrically connected to the heating element 31.

[0018] The terminals 41a and the wiring 41b are formed using a material containing, for example, silver, copper, etc. For example, the terminals 41a and the wiring 41b can be formed by applying a paste-like material onto the insulating portion 21 using a screen printing method or the like, and then curing the paste using a baking method or the like.

[0019] The protective portion 51 is provided, for example, on the insulating portion 21 and extends along the longitudinal direction (X direction) of the substrate 10. The protective portion 51 covers, for example, the heating element 31 and the wiring 41b. In this case, the terminal 41a is exposed from the protective portion 51.

[0020] The protective portion 51 has functions, for example, to insulate the heating element 31 and the wiring 41b, to transfer heat generated in the heating element 31 to the outside, and to protect the heating element 31 and the wiring 41b from external forces, corrosive gases, and the like. The protective portion 51 is formed from a material that is heat-resistant and insulating, and has high chemical stability and thermal conductivity. The protective portion 51 is formed from an inorganic material, such as ceramics or glass. In this case, the protective portion 51 can also be formed using a glass material to which a filler containing a material with high thermal conductivity, such as aluminum oxide, has been added. The thermal conductivity of the glass material to which the filler has been added can be, for example, 2 [W / (m·K)] or more.

[0021] The protective portion 51 can be formed, for example, by applying a paste-like material onto the insulating portion 21, the heating element 31, and the wiring 41b using a screen printing method or the like, and then hardening it using a baking method or the like.

[0022] 2 and 3, the insulating portion 22 has insulating properties and is provided on the surface 10b of the substrate 10. The insulating portion 22 can be provided, for example, so as to cover the surface 10b of the substrate 10. The insulating portion 22 is provided to insulate the metal-containing substrate 10 from the heating element 32 and the wiring portion 42. Therefore, the insulating portion 22 is provided between the substrate 10 and the heating element 32 and the wiring portion 42. The formation area, thickness, material, and formation method of the insulating portion 22 can be, for example, the same as the formation area, thickness, material, and formation method of the insulating portion 21 described above.

[0023] The heating element 32 converts the applied power into heat (Joule heat) and is provided on the insulating part 22 (on the surface of the insulating part 22 opposite to the substrate 10 side). The heating element 32 extends, for example, along the longitudinal direction (X direction) of the substrate 10. The heating element 32 can be formed using, for example, ruthenium oxide (RuO2) or a silver-palladium (Ag-Pd) alloy. The heating element 32 can be formed, for example, by applying a paste material onto the insulating part 22 using a screen printing method or the like, and then curing it using a baking method or the like.

[0024] The wiring section 42 is provided, for example, on the surface of the insulating section 22 on which the heating element 32 is provided. The wiring section 42 has, for example, a terminal 42a and a wire 42b. For example, a pair of terminals 42a may be provided. Each of the pair of terminals 42a may be provided near the end portions of the substrate 10 on both sides in the X direction. The pair of terminals 42a may be electrically connected to a power supply, a control circuit, or the like via a connector, wiring, or the like.

[0025] For example, a pair of wires 42b may be provided. Each of the pair of wires 42b electrically connects the terminal 42a and the heating element 32. One end of the wire 42b is electrically connected to the terminal 42a. The other end of the wire 42b is electrically connected to the heating element 32. The material and method of forming the terminals 42a and the wiring 42b can be the same as the material and method of forming the terminals 41a and the wiring 41b described above.

[0026] The protective portion 52 is provided, for example, on the insulating portion 22 and extends along the longitudinal direction (X direction) of the substrate 10. The protective portion 52 covers, for example, the heating element 32 and the wiring 42b. In this case, the terminal 42a is exposed from the protective portion 52.

[0027] The function, material, and method of forming the protective portion 52 may be the same as the function, material, and method of forming the protective portion 51 described above.

[0028] The heater 1 may further be provided with a detection unit that detects the temperature of the heating element 31 and a detection unit that detects the temperature of the heating element 32. The detection units may be, for example, a thermistor. The detection units may be provided on at least one of the side of the substrate 10 where the heating element 31 is provided and the side of the substrate 10 where the heating element 32 is provided. In this case, the protective units 51 and 52 may cover the detection units.

[0029] In recent years, there has been a demand for a single heater that can heat objects of different sizes, i.e., versatility for various sizes of objects. In this case, heating elements of different lengths can be arranged in the Y direction on one side of the substrate. This allows heating elements of different lengths to be selected and used depending on the size of the object to be heated. However, this increases the dimension (width) of the substrate in the Y direction, making it difficult to miniaturize the heater. Furthermore, when the heating range is switched depending on the size of the object to be heated, the temperature difference in the longitudinal direction of the long substrate becomes large. Since substrates made of ceramics are generally used, a large temperature difference in the longitudinal direction of the long substrate may cause the substrate to crack due to thermal stress.

[0030] Therefore, the heater 1 according to this embodiment includes a heating element 31 provided on the surface 10a of the substrate 10 and a heating element 32 provided on the surface 10b of the substrate 10. As shown in Figures 1 and 2, the length L2 of the heating element 32 in the X direction is different from the length L1 of the heating element 31 in the X direction. For example, the length L2 can be shorter than the length L1.

[0031] For example, if the objects to be heated are A3-sized paper and B5-sized paper, heating element 31 can be used to heat the A3-sized paper, and heating element 32 can be used to heat the B5-sized paper. When heating element 31 is used to heat A3-sized paper, length L1 can be set to approximately 322 mm. When heating element 32 is used to heat B5-sized paper, length L2 can be set to approximately 184 mm.

[0032] Furthermore, it is preferable that the center of heating element 32 is located at the same position as the center of heating element 31 in the X direction. In this way, when heater 1 is attached to image forming apparatus 100, it becomes easy to align the centers of heating elements 31 and 32 with the center of the transport path of the object to be heated. Therefore, even if the dimension of the object to be heated in the direction perpendicular to the transport direction changes, it becomes easy to heat the object to be heated approximately uniformly.

[0033] Furthermore, the width dimension W2, thickness, and material of the heat generating element 32 may be the same as the width dimension W1, thickness, and material of the heat generating element 31, or any of these may be different.

[0034] 1 to 3 illustrate an example in which one heating element 31 is provided, but it is sufficient that at least one heating element 31 is provided. Also, while FIGS. 1 to 3 illustrate an example in which one heating element 32 is provided, it is sufficient that at least one heating element 32 is provided. The number of heating elements 31 and 32 can be changed appropriately depending on the amount of heat to be applied to the heated object, etc. However, when multiple heating elements 31 are provided, the multiple heating elements 31 are arranged side by side in the Y direction. When multiple heating elements 32 are provided, the multiple heating elements 32 are arranged side by side in the Y direction. As a result, the width dimension W of the substrate 10 becomes large, which may make it difficult to miniaturize the heater 1.

[0035] Therefore, it is preferable to reduce the number of heating elements 31 by changing the resistance value of the heating elements 31 according to the required heat generation amount. For example, the number of heating elements 31 can be reduced by changing the material, width dimension W1, and thickness of the heating elements 31. It is also preferable to reduce the number of heating elements 32 by changing the resistance of the heating elements 32 depending on the amount of heat required. For example, the number of heating elements 32 can be reduced by changing the material, width dimension W2, and thickness of the heating elements 32.

[0036] Furthermore, because the lengths of heating element 31 and heating element 32 are different, switching between heating elements 31 and 32 changes the range of heating on substrate 10. For example, switching heating element 31 to heating element 32 reduces the range of heating on substrate 10 in the X direction. For example, switching heating element 32 to heating element 31 increases the range of heating on substrate 10 in the X direction. If the range of heating on substrate 10 changes, it is conceivable that thermal stress may cause deformation or damage to substrate 10. However, surface 10a of substrate 10 is provided with insulating portion 21, wiring portion 41, and protective portion 51. Surface 10b of substrate 10 is provided with insulating portion 22, wiring portion 42, and protective portion 52. Therefore, for example, thermal stress generated on surface 10a of substrate 10 can be offset by thermal stress generated on surface 10b of substrate 10. As a result, deformation or damage to substrate 10 can be suppressed.

[0037] Furthermore, as described above, the substrate 10 is made of metal. This increases the rigidity and toughness of the substrate 10. If the rigidity and toughness of the substrate 10 can be increased, deformation or damage to the substrate 10 can be suppressed even if thermal stress occurs due to switching between the heating elements 31 and 32. As described above, the heater 1 according to this embodiment can switch the heating range depending on the size of the object to be heated, and can also be made smaller and damage to the substrate 10 can be prevented.

[0038] (Image forming device) Next, an example of the image forming apparatus 100 according to the present embodiment will be described. In the following, a case where the image forming apparatus 100 is a copier will be described as an example. 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 the like. It may also be a rewritable card reader / writer or the like.

[0039] FIG. 4 is a schematic diagram illustrating the image forming apparatus 100 according to the present embodiment. FIG. 5 is a schematic diagram illustrating the fixing unit 200. As shown in FIG. As shown in FIG. 4, 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 discharging unit 151, a developing unit 160, a cleaner 170, a storage unit 180, a conveying unit 190, a fixing unit 200, and a controller 210.

[0040] The frame 110 is box-shaped and houses an illumination unit 120, an imaging element 130, a photosensitive drum 140, a charging unit 150, a developing unit 160, a cleaner 170, part of a storage unit 180, a conveying unit 190, a fixing unit 200, and a controller 210 inside. A window 111 made of a light-transmitting material such as glass may be provided on the top surface of the frame 110. An original 500 to be copied is placed on the window 111. A moving unit for moving the position of the original 500 may also be provided.

[0041] 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 rotatable. 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 .

[0042] 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 has been fixed.

[0043] 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 to 194 that transport the paper 510. The transport unit 190 can also be provided with a motor that rotates the transport rollers 192 to 194.

[0044] The fixing unit 200 is provided downstream of the photosensitive drum 140 (on the tray 182 side). As shown in FIG. 5, 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. For example, the side of the heater 1 on which the protective part 51 is provided can be exposed from the stay 201.

[0045] The film belt 202 covers the stay 201 provided with the heater 1. The film belt 202 can be made of a heat-resistant resin such as polyimide.

[0046] The pressure roller 203 is disposed opposite the stay 201. The pressure roller 203 has, for example, a core 203a, a drive shaft 203b, and an elastic portion 203c. The drive shaft 203b protrudes from the end of the core 203a and is connected to a driving device such as a motor. The elastic portion 203c is disposed on the outer surface of the core 203a. The elastic portion 203c is formed from a heat-resistant elastic material. The elastic portion 203c can be formed from, for example, a silicone resin.

[0047] 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, etc., and a display unit that displays the operating status and abnormality indications, etc. It should be noted that the control of each element provided in the image forming apparatus 100 can be performed using known techniques, and therefore detailed description thereof will be omitted.

[0048] Although several embodiments of the present invention have been described above, these embodiments are presented by way of example only and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, modifications, etc. can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as set forth in the claims. Furthermore, the above-described embodiments can be implemented in combination with each other. [Explanation of symbols]

[0049] 1 heater, 10 substrate, 10a surface, 10b surface, 21 insulating portion, 22 insulating portion, 31 heating element, 32 heating element, 41 wiring portion, 42 wiring portion, 51 protective portion, 52 protective portion, 100 image forming apparatus, 200 fixing portion

Claims

1. a substrate including a metal and having a shape extending in one direction; a first insulating portion provided on a first surface of the substrate and having insulating properties; a single first heating element provided on the first insulating portion and extending along the longitudinal direction of the substrate; a pair of first wirings provided on the first insulating portion and electrically connected to opposite end portions of the first heating element; a first protective portion provided on the first insulating portion, extending along the longitudinal direction of the substrate, and covering the first heating element and the pair of first wirings; a pair of first terminals provided on the first insulating portion and electrically connected to ends of the pair of first wirings opposite to the first heating element side; a second insulating portion having insulating properties and provided on a second surface of the substrate opposite to the first surface; a single second heating element provided on the second insulating portion and extending along the longitudinal direction of the substrate; a pair of second wirings provided on the second insulating portion and electrically connected to opposite end portions of the second heating element; a second protective portion provided on the second insulating portion, extending along the longitudinal direction of the substrate, and covering the second heating element and the pair of second wirings; a pair of second terminals provided on the second insulating portion and electrically connected to the ends of the pair of second wirings opposite to the second heating element side; Equipped with a length of the second heating element in the longitudinal direction of the substrate is different from a length of the first heating element; a center of the second heating element is located at the same position as a center of the first heating element in the longitudinal direction of the substrate; In the short-side direction of the substrate, a center of the first heating element and a center of the second heating element are located at the center of the substrate, The heater, when viewed from a direction intersecting the first surface, has the first wiring and the second wiring overlapping, and the first terminal and the second terminal overlapping.

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

Images