HEATER AND IMAGE FORMING APPARATUS

Abstract

To provide a heater that can prevent the occurrence of warpage, and an image forming apparatus.SOLUTION: A heater 1 is provided with: a substrate 10; heating elements 21, 22 that are provided on a first surface of the substrate and extend along a longitudinal direction of the substrate; a protective part 40 that is provided on the first surface, extends along the longitudinal direction of the substrate, and covers the heating elements; and at least one relaxation part 50 that is provided on a second surface opposite to the first surface of the substrate. The coefficient of thermal expansion of the protective part and the coefficient of thermal expansion of the relaxation part are different from the coefficient of thermal expansion of the substrate. A material of the relaxation part is the same as a material of the protective part, or a main component of the material of the relaxation part is the same as a main component of the material of the protective part.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] 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 provided with heaters for fixing toner. 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] The substrate is made of a material that is heat resistant, insulating, and has high thermal conductivity, such as ceramics such as aluminum oxide, or a metal core substrate in which the surface of a metal plate is coated with an insulating material. The protective portion is made of a material that has heat resistance and insulation properties, high thermal conductivity, and high chemical stability, such as ceramics, glass, etc.

[0004] Here, the material of the substrate and the material of the protective part may be different. If the material of the substrate and the material of the protective part are different, thermal stress may occur due to the difference in thermal expansion coefficient of the materials, and the heater may warp. In this case, the greater the difference between the thermal expansion coefficient of the substrate and the thermal expansion coefficient of the protective part, the more likely the heater is to warp.

[0005] If the heater is warped, the distance between the heater and the object to be heated may vary, resulting in uneven heating of the object to be heated. Therefore, there has been a demand for the development of a technique that can prevent the heater from warping. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2007-240606 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 capable of suppressing the occurrence of warping. [Means for solving the problem]

[0008] The heater according to the embodiment includes a substrate; a heating element provided on a first surface of the substrate and extending along the longitudinal direction of the substrate; a protective portion provided on the first surface, extending along the longitudinal direction of the substrate, and covering the heating element; and a protective portion provided on a second surface of the substrate opposite to the first surface. , aligned along the longitudinal direction of the substrate Established multiple and a relaxation part; The thermal expansion coefficient of the protection part and the thermal expansion coefficient of the relaxation part are different from the thermal expansion coefficient of the substrate, and the material of the relaxation part is the same as the material of the protection part, or the main component of the material of the relaxation part is the same as the main component of the material of the protection part. At least one of the arrangement position, the material, the planar dimension, and the thickness of each of the plurality of relaxation portions is set so as to suppress warping of the heater. . Effect of the Invention

[0009] According to an embodiment of the present invention, it is possible to provide a heater and an image forming apparatus capable of suppressing the occurrence of warping. [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] 1 is a schematic diagram illustrating an image forming apparatus according to an embodiment of the present invention; [Diagram 5] 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 will be omitted as 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 substrate surface 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 and the protective portion 40 are 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 seen from the side where the relaxation portion 50 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, a heat generating portion 20, a wiring portion 30, a protective portion 40, and a relaxation portion 50, for example.

[0013] The substrate 10 has a plate-like shape extending in one direction (for example, the X direction). The planar shape of the substrate 10 is, for example, a long rectangular shape. The thickness of the substrate 10 can be, for example, about 0.5 mm to 1.0 mm. The planar dimensions of the substrate 10 can be appropriately changed depending on the size of the object to be heated (for example, paper), etc.

[0014] The substrate 10 is made of a material having heat resistance, insulation properties, and high thermal conductivity, such as ceramics such as aluminum oxide or aluminum nitride, crystallized glass (glass ceramics), or a metal core substrate.

[0015] The metal core substrate has a metal plate made of, for example, stainless steel and an insulating layer covering the surface of the metal plate. The insulating layer can be made of, for example, an inorganic material such as ceramics. The thermal conductivity of the metal core substrate including the metal plate is higher than that of ceramics. Therefore, if the substrate 10 is made of a metal core substrate, it is possible to suppress the occurrence of in-plane temperature distribution of the heater 1.

[0016] The heat generating portion 20 converts the applied power into heat (Joule heat). The heat generating portion 20 can be provided on the surface 10a of the substrate 10 (corresponding to an example of the first surface). The heat generating unit 20 has, for example, a heat generating element 21 and a heat generating element 22. Although the case where the heat generating element 21 and the heat generating element 22 are provided has been illustrated as an example, the number and size of the heat generating elements can be appropriately changed according to the size of the object to be heated. In addition, multiple types of heat generating elements with different lengths, widths, shapes, etc. can also be provided. In other words, it is sufficient that at least one heat generating element is provided.

[0017] Heating element 21 and heating element 22 are arranged, for example, at a predetermined interval in the Y direction (short side direction of substrate 10). Heating element 21 and heating element 22 have a form extending, for example, along the X direction (longitudinal direction of substrate 10).

[0018] The dimensions (length dimensions) of the 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 the heating elements 21 and 22 are located on the straight line 1a. In other words, it is preferable that the heating elements 21 and 22 are arranged so as to be symmetrical with respect to the straight line 1a.

[0019] When the heater 1 is attached 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 size of the object to be heated in the direction perpendicular to the transport direction changes, the object to be heated can be easily heated substantially uniformly.

[0020] The electrical resistance values ​​of the heating elements 21 and 22 can be approximately the same or different. For example, the electrical resistance values ​​can be approximately the same by making the dimensions in the X direction (length dimension), the Y direction (width dimension), and the Z direction (thickness dimension) of the heating elements 21 and 22 approximately the same. Also, by changing at least one of these dimensions, the electrical resistance values ​​can be made different. Also, by changing the material, the electrical resistance values ​​can be made different.

[0021] Furthermore, the electrical resistance value per unit length of the heating element 21 can be approximately uniform in the X direction. For example, the dimension (width dimension) in the Y direction and the dimension (thickness dimension) in the Z direction of the heating element 21 can be approximately constant. The planar shape of the heating element 21 can be, for example, approximately rectangular extending along the X direction (the longitudinal direction of the substrate 10).

[0022] Furthermore, the electrical resistance value per unit length of the heating element 22 can be approximately uniform in the X direction. For example, the dimension (width dimension) in the Y direction and the dimension (thickness dimension) in the Z direction of the heating element 22 can be approximately constant. The planar shape of the heating element 22 can be, for example, approximately rectangular extending along the X direction (the longitudinal direction of the substrate 10).

[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 substrate 10 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, for example, on the surface 10a of the substrate 10 on which the heat generating portion 20 (heat generating element 21 and heat generating element 22) is provided. The wiring section 30 includes, for example, a terminal 31, a terminal 32, a wire 33, a wire 34, and a wire 35.

[0025] The terminals 31 and 32 are provided, for example, near one end of the substrate 10 in the X direction. The terminals 31 and 32 can be provided side by side in the X direction. The terminals 31 and 32 are electrically connected, for example, to a power source via a connector, wiring, or the like.

[0026] The wiring 33 is provided, for example, in the X direction, on the side of the substrate 10 where the terminal 31 is provided. The wiring 33 has a form extending in the X direction. The wiring 33 is electrically connected to the terminal 31 and an end of the heating element 21 on the terminal 31 side.

[0027] The wiring 34 is provided, for example, in the X direction, near the end of the substrate 10 opposite to the side on which the terminals 31 and 32 are provided. The wiring 34 is electrically connected to 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.

[0028] The wiring 35 is provided, for example, in the X direction, on the side of the substrate 10 where the terminal 32 is provided. The wiring 35 has a form extending in the X direction. The wiring 35 is electrically connected to the terminal 32 and the end of the heating element 22 on the terminal 32 side.

[0029] The wiring portion 30 (terminals 31, 32 and wires 33 to 35) are formed using a material containing, for example, silver, copper, etc. For example, the terminals 31, 32 and wires 33 to 35 can be formed by applying a paste-like material onto the substrate 10 using a screen printing method or the like, and curing it using a baking method or the like.

[0030] The protective portion 40 is provided, for example, on the surface 10a of the substrate 10 on which the heat generating portion 20 is provided. The protective portion 40 has a form extending, for example, along the X direction (the longitudinal direction of the substrate 10). The protective portion 40 covers the heat generating portion 20 (heat generating elements 21, 22) and a part of the wiring portion 30 (wires 33-35). In this case, the terminals 31, 32 can be exposed from the protective portion 40.

[0031] 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, 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, for example, ceramics, glass, and the like. 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, 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.

[0032] The heater 1 may further be provided with a detection unit that detects the temperature of the heat generating unit 20 (heat generating elements 21, 22). The detection unit may be, for example, a thermistor. The detection unit may be provided on at least one of the surface 10a of the substrate 10 on which the heat generating unit 20 is provided and the surface 10b (corresponding to an example of a second surface) of the substrate 10 opposite to the surface on which the heat generating unit 20 is provided. Also, for example, wiring and terminals electrically connected to the detection unit are provided on the surface of the substrate 10 on which the detection unit is provided. For example, the detection unit and wiring may be covered by the protective unit 40, and the terminals may be exposed from the protective unit 40.

[0033] As described above, the substrate 10 is made of, for example, ceramics such as aluminum oxide or aluminum nitride, crystallized glass (glass ceramics), a metal core substrate, etc. On the other hand, the protective portion 40 is made of, for example, ceramics, glass, glass with added filler, etc.

[0034] Therefore, the thermal expansion coefficient of the substrate 10 and the thermal expansion coefficient of the protective part 40 may differ. Furthermore, when the heater 1 is used and the heater 1 is caused to generate heat, the substrate 10 and the protective part 40 are heated. When the protective part 40 is baked during the manufacture of the heater 1, the substrate 10 and the protective part 40 are heated. Therefore, when the heater 1 is used or manufactured, thermal stress may occur due to the difference in the thermal expansion coefficients of the materials, and the heater 1 may warp.

[0035] In this case, if the length of the substrate 10 in the short direction (width direction: for example, Y direction) is short, if the length of the substrate 10 in the long direction (for example, X direction) is long, or if the thickness of the substrate 10 is thin, the heater 1 is likely to warp. In addition, since the metal core substrate is based on a metal plate, it has a larger coefficient of thermal expansion than inorganic materials such as ceramics and crystallized glass. Therefore, when the substrate 10 is a metal core substrate, the difference in the coefficient of thermal expansion becomes even larger, so that the heater 1 is more likely to warp or the warp may become larger.

[0036] If the heater 1 is warped, the distance between the heater 1 and the object to be heated varies, which may result in uneven heating of the object to be heated. Therefore, the heater 1 is provided with a relaxation portion 50.

[0037] 2 and 3, the relaxation portion 50 is provided on a surface 10b opposite to the surface 10a of the substrate 10. When viewed from a direction perpendicular to the surface 10a (10b) of the substrate 10 (Z direction), at least a portion of the relaxation portion 50 overlaps with the protective portion 40.

[0038] It is possible to provide at least one relaxation section 50. When a plurality of relaxation sections 50 are provided, the plurality of relaxation sections 50 can be arranged side by side in the longitudinal direction (X direction) of the substrate 10 as shown in FIG.

[0039] The thermal expansion coefficient of the relaxation portion 50 is different from that of the substrate 10. If the thermal expansion coefficient of the relaxation portion 50 is different from that of the substrate 10, thermal stress occurs during use of the heater 1 or during manufacture of the heater 1 due to the difference in the thermal expansion coefficients of the materials.

[0040] However, since the relaxation portion 50 is provided on the surface 10b of the substrate 10 opposite to the surface 10a on which the protective portion 40 is provided, the thermal stress caused by the substrate 10 and the protective portion 40 can be offset by the thermal stress caused by the substrate 10 and the relaxation portion 50. If the thermal stresses are offset, the occurrence of warping in the heater 1 can be suppressed. In other words, if the relaxation portion 50 is provided, the occurrence of warping in the heater 1 can be suppressed.

[0041] In this case, it is preferable that the magnitude of the thermal stress generated by the substrate 10 and the relaxation section 50 is as similar as possible to the magnitude of the thermal stress generated by the substrate 10 and the protective section 40. Therefore, it is preferable that the thermal expansion coefficient of the relaxation section 50 is the same as or close to the thermal expansion coefficient of the protective section 40. For example, the material of the relaxation section 50 can be the same as the material of the protective section 40. For example, the main component of the material of the relaxation section 50 can be the same as the main component of the material of the protective section 40. In this case, if the material of the relaxation section 50 is the same as the material of the protective section 40, it is possible to simplify the manufacturing process, improve productivity, reduce manufacturing costs, and the like.

[0042] Furthermore, by changing at least one of the planar dimensions and thickness of the relaxation section 50, it is possible to suppress the occurrence of warping or reduce the magnitude of warping. However, if the difference between the volume of the relaxation section 50 and the volume of the protective section 40 becomes large, the effect of offsetting the thermal stress decreases. Therefore, for example, when the material of the relaxation section 50 is the same as the material of the protective section 40 or has the same main component, it is preferable to make the volume of the relaxation section 50 approximately the same as the volume of the protective section 40. For example, when the volume of the protective section 40 is V1 (mm 3 ), and the volume of the relaxation portion 50 is V2 (mm 3 ), it is preferable that "0.9≦V2 / V1≦1.1" be satisfied. It is even more preferable that "0.94≦V2 / V1≦1.06" be satisfied.

[0043] Furthermore, when multiple relaxation sections 50 are provided, it is possible to suppress the occurrence of warping or reduce the magnitude of warping by changing at least one of the arrangement positions, material, and volume (planar dimensions, thickness) of the multiple relaxation sections 50. The arrangement positions, material, and volume of the multiple relaxation sections 50 can be appropriately determined by conducting experiments and simulations.

[0044] Furthermore, when a plurality of relaxation portions 50 are provided, a space can be provided between the relaxation portions 50 as shown in Fig. 2. If a space is provided between the relaxation portions 50, a jig 60 can be provided in the space when manufacturing the heater 1. If the jig 60 is provided in the space, for example, bending of the substrate 10 can be suppressed when firing the plurality of relaxation portions 50. Therefore, deformation of the heater 1 can be suppressed when manufacturing the heater 1.

[0045] However, if the distance L between the relaxation portions 50 is too large, the effect of offsetting the thermal stress is reduced. Therefore, it is preferable that the distance L between the relaxation portions 50 is 7 mm or less. For example, if the distance L is about 5 mm, it is possible to suppress the effect of offsetting the thermal stress from being reduced, and the arrangement of the jig 60 becomes easy.

[0046] (Image forming device) Next, an image forming apparatus 100 equipped with the heater 1 will be illustrated. In the following, as an example, a case where the image forming apparatus 100 is a copier will be described. 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.

[0047] FIG. 4 is a schematic diagram illustrating an 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 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.

[0048] 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.

[0049] 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 .

[0050] 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.

[0051] 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.

[0052] 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. In this case, the side of the heater 1 on which the protective part 40 is provided is exposed from the stay 201.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 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. [Explanation of symbols]

[0057] 1 heater, 10 substrate, 10a surface, 10b surface, 20 heat generating section, 21 heat generating element, 22 heat generating element, 30 wiring section, 40 protection section, 50 relaxation section, 100 image forming apparatus, 200 fixing section

Claims

1. A substrate; a heating element provided on a first surface of the substrate and extending along a longitudinal direction of the substrate; a protective portion provided on the first surface, extending along the longitudinal direction of the substrate, and covering the heating element; a plurality of relaxation portions arranged along a longitudinal direction of the substrate on a second surface of the substrate opposite to the first surface; Equipped with a thermal expansion coefficient of the protection portion and a thermal expansion coefficient of the relaxation portion are different from a thermal expansion coefficient of the substrate, The material of the relaxation part is the same as the material of the protection part, or A main component of the material of the relaxation portion is the same as a main component of the material of the protection portion, A heater in which at least one of the arrangement position, the material, the planar dimension, and the thickness of each of the plurality of relaxation portions is set so as to suppress warping of the heater.

2. A heater as described in claim 1, wherein the distance between the relaxation portions is 7 mm or less.

3. The volume of the protective part is V1 (mm ３ )year, The volume of the plurality of relaxation portions is V2 (mm ３ 3. The heater according to claim 1, wherein the following formula is satisfied: 0.9≦V2 / V1≦1.1

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

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