Heater and image heating device

Abstract

A heater and an image heating apparatus are disclosed. A heater in which first and second heat generating resistors are disposed on an elongated substrate along a longitudinal direction at positions offset from a center in a lateral direction toward opposite long sides of each other, and these resistors are connected in series via a third conductor. Exposed first and second electrical contacts are provided at one end side of the substrate. The second electrical contact is arranged farther from the one end in the longitudinal direction than the first electrical contact, and the positions of these electrical contacts overlap each other in the lateral direction. Each contact is connected with a resistor via a conductor. The conductor includes a widened portion at the contact side and a tapered portion in which the width decreases toward the connection position.

Description

Technical Field

[0001] This disclosure relates to a heater and an image heating apparatus for heating recording materials. Background Technology

[0002] As image heating devices installed in electrophotographic copiers and printers, image heating devices using film heating methods are known. Film-heated fixing equipment includes a tubular film, a heating element in contact with the inner surface of the film, and a pressure roller that forms a clamping portion together with the heating element via the film. A common example used as the heating element is a ceramic heater comprising a substrate on which heating resistors are formed.

[0003] The heater described in Japanese Patent Publication No. 2008-140702 includes two heating resistors arranged in parallel on a substrate and two power supply electrodes (electrical contacts) arranged on one longitudinal end of the substrate. When the size of the power supply electrodes is small, it is also conceivable to use a configuration in which the two heating resistors and the two power supply electrodes are connected separately via conductors.

[0004] Then, when the distance between the aforementioned conductors is shortened due to the reduction in the size of the substrate, leakage current may flow undesirably between the two conductors, and if leakage current is generated between opposite polarities, thermal damage to the heater may occur unexpectedly. Summary of the Invention

[0005] In these cases, this disclosure aims to provide a heater and an image heating device that suppress leakage current between two conductors.

[0006] According to one aspect of this disclosure, a heater includes: an elongated substrate having a first long side and a second long side when the heater is viewed in a direction perpendicular to a plane of the substrate; a first heating resistor disposed on the substrate along a longitudinal direction, the first heating resistor being arranged at a position offset from the center of the substrate in a lateral direction toward the first long side; a second heating resistor disposed on the substrate along the longitudinal direction, the second heating resistor being arranged at a position offset from the center in the lateral direction toward the second long side; and a first electrical contact contacting a first terminal for supplying power to the first heating resistor and, via the first heating resistor, to the second heating resistor, the first electrical contact being arranged at a position closer to one end of the substrate in the longitudinal direction than the first heating resistor, and the first electrical contact being electrically connected to one end of the first heating resistor in the longitudinal direction. A second electrical contact, which contacts a second terminal for supplying power to the second heating resistor and, via the second heating resistor, to the first heating resistor, is positioned in the longitudinal direction closer to one end of the substrate than the second heating resistor, and is electrically connected to one end of the second heating resistor in the longitudinal direction; a first conductor, which is positioned in the longitudinal direction between the first heating resistor and the first electrical contact, and is electrically connected to the first heating resistor and the first electrical contact; a second conductor, which is positioned in the longitudinal direction between the second heating resistor and the second electrical contact, and is electrically connected to the second heating resistor and the second electrical contact; and a third conductor, which is electrically connected to the other end of the first heating resistor opposite to one end of the first heating resistor in the longitudinal direction, and to the other end of the second heating resistor opposite to one end of the second heating resistor in the longitudinal direction.An insulating layer covers the first heating resistor, the second heating resistor, the first conductor, the second conductor, and the third conductor, with the first and second electrical contacts exposed. The first and second heating resistors are connected in series via the third conductor. The second electrical contact is located at a position further from the substrate in the longitudinal direction than the first electrical contact. The positions of the first and second electrical contacts overlap in the transverse direction. A first widening portion is provided in the region of the first conductor on the side closer to the substrate than the first connection position of the first conductor and the first heating resistor. The width of the first widening portion in the transverse direction is greater than the width of the first connection position in the transverse direction. A second widening portion is provided in the region of the second conductor on the side closer to the substrate than the second connection position of the second conductor and the second heating resistor. The second widening portion in the transverse direction... The width in the longitudinal direction is wider than the width of the second connection position in the transverse direction. A first width-changing portion is disposed in the region of the first conductor between the first widened portion and the first connection position in the longitudinal direction. The first width-changing portion has a width that decreases from the first widened portion toward the first connection position in the transverse direction. A second width-changing portion is disposed in the region of the second conductor between the second widened portion and the second connection position in the longitudinal direction. The second width-changing portion has a width that decreases from the second widened portion toward the second connection position in the transverse direction. The first long side of the first width-changing portion facing the substrate has a linear shape parallel to the first long side. The second long side of the second width-changing portion facing the substrate has a linear shape parallel to the second long side. Furthermore, in the transverse direction, the distance between the first connection position and the second connection position is longer than the distance between the first widened portion and the second widened portion.

[0007] According to another aspect of this disclosure, a heater includes: an elongated substrate having a first long side and a second long side when the heater is viewed in a direction perpendicular to a plane of the substrate; a first heating resistor disposed on the substrate along a longitudinal direction, the first heating resistor being arranged at a position offset from the center of the substrate in a lateral direction toward the first long side; a second heating resistor disposed on the substrate along the longitudinal direction, the second heating resistor being arranged at a position offset from the center in the lateral direction toward the second long side; and a first electrical contact contacting a first terminal for supplying power to the first heating resistor and, via the first heating resistor, to the second heating resistor, the first electrical contact being arranged at a position closer to one end of the substrate in the longitudinal direction than the first heating resistor, and the first electrical contact being electrically connected to one end of the first heating resistor in the longitudinal direction. A second electrical contact, which contacts a second terminal for supplying power to the second heating resistor and, via the second heating resistor, to the first heating resistor, is positioned in the longitudinal direction closer to one end of the substrate than the second heating resistor, and is electrically connected to one end of the second heating resistor in the longitudinal direction; a first conductor, which is positioned in the longitudinal direction between the first heating resistor and the first electrical contact, and is electrically connected to the first heating resistor and the first electrical contact; a second conductor, which is positioned in the longitudinal direction between the second heating resistor and the second electrical contact, and is electrically connected to the second heating resistor and the second electrical contact; and a third conductor, which is electrically connected to the other end of the first heating resistor opposite to one end of the first heating resistor in the longitudinal direction, and to the other end of the second heating resistor opposite to one end of the second heating resistor in the longitudinal direction.An insulating layer covers the first heating resistor, the second heating resistor, the first conductor, the second conductor, and the third conductor when the first and second electrical contacts are exposed. The first and second heating resistors are connected in series via the third conductor. The second electrical contact is positioned at a location different from the first electrical contact in the longitudinal direction. The positions of the first and second electrical contacts overlap in the transverse direction. A widening portion is provided in the region of the first conductor on the side closer to the substrate than the connection point of the first conductor and the first heating resistor. The width of the widening portion in the transverse direction is wider than the width of the connection point in the transverse direction. A width-changing portion is provided. In the region of the first conductor between the widened portion and the connection position in the longitudinal direction, the width-changing portion has a width that decreases from the widened portion toward the connection position in the transverse direction. The side of the width-changing portion facing the substrate, on the first long side, has a linear shape parallel to the first long side. The side of the second conductor facing the substrate, located in the same region in the longitudinal direction as the width-changing portion, also has a linear shape parallel to the second long side. Furthermore, in the transverse direction, the distance between the connection position of the first conductor and the first heating resistor and the connection position of the second conductor and the second heating resistor is longer than the distance between the widened portion and the region of the second conductor located in the same position in the longitudinal direction as the widened portion.

[0008] According to another aspect of this disclosure, a heater includes: an elongated substrate having a first long side and a second long side when the heater is viewed in a direction perpendicular to a plane of the substrate; a first heating resistor disposed on the substrate along a longitudinal direction, the first heating resistor being arranged at a position offset from the center of the substrate in a transverse direction toward the first long side; a second heating resistor disposed on the substrate along the longitudinal direction, the second heating resistor being arranged at a position offset from the center in the transverse direction toward the second long side; and a first electrical contact contacting a first terminal for supplying power to the first heating resistor and, via the first heating resistor, to the second heating resistor, the first electrical contact being arranged at a position closer to one end of the substrate in the longitudinal direction than the first heating resistor, and the first electrical contact being electrically connected to one end of the first heating resistor in the longitudinal direction. A second electrical contact, which contacts a second terminal for supplying power to the second heating resistor and, via the second heating resistor, to the first heating resistor, is positioned in the longitudinal direction closer to one end of the substrate than the second heating resistor, and is electrically connected to one end of the second heating resistor in the longitudinal direction; a first conductor, which is positioned in the longitudinal direction between the first heating resistor and the first electrical contact, and is electrically connected to the first heating resistor and the first electrical contact; a second conductor, which is positioned in the longitudinal direction between the second heating resistor and the second electrical contact, and is electrically connected to the second heating resistor and the second electrical contact; and a third conductor, which is electrically connected to the other end of the first heating resistor opposite to one end of the first heating resistor in the longitudinal direction, and to the other end of the second heating resistor opposite to one end of the second heating resistor in the longitudinal direction.An insulating layer covers the first heating resistor, the second heating resistor, the first conductor, the second conductor, and the third conductor, with the first and second electrical contacts exposed. The first and second heating resistors are connected in series via the third conductor. The second electrical contact is located at a position further from the substrate in the longitudinal direction than the first electrical contact. The positions of the first and second electrical contacts overlap in the transverse direction. A first widening portion is provided in the region of the first conductor on the side closer to the substrate than the first connection position of the first conductor and the first heating resistor. The width of the first widening portion in the transverse direction is wider than the width of the first connection position in the transverse direction. A second widening portion is provided in the region of the second conductor on the side closer to the substrate than the second connection position of the second conductor and the second heating resistor. In the region, the width of the second widened portion in the lateral direction is wider than the width of the second connection position in the lateral direction. A first constant-width portion is disposed in all regions of the first conductor between the first widened portion and the first connection position in the longitudinal direction, and the first constant-width portion has a constant width in the lateral direction. A second constant-width portion is disposed in all regions of the second conductor between the second widened portion and the second connection position in the longitudinal direction, and the second constant-width portion has a constant width in the lateral direction. The first long side of the first constant-width portion facing the substrate has a linear shape parallel to the first long side, and the second long side of the second constant-width portion facing the substrate has a linear shape parallel to the second long side. Furthermore, in the lateral direction, the distance between the first connection position and the second connection position is longer than the distance between the first widened portion and the second widened portion.

[0009] The features of this disclosure will become clear from the following description of embodiments with reference to the accompanying drawings. The following description of the embodiments is provided as examples. Attached Figure Description

[0010] Figure 1 The diagram illustrates an image forming apparatus.

[0011] Figure 2 The image heating device is illustrated.

[0012] Figure 3 The diagram illustrates the electrical connection configuration of the heater according to the first embodiment.

[0013] Figures 4A to 4E Each illustration shows the shape of the conductor of the heater according to the first embodiment.

[0014] Figures 5A to 5D Each illustration shows the positional relationship between the heater and the pressurizing member according to the first embodiment.

[0015] Figure 6 The diagram illustrates the electrical connection configuration of the heater according to the second embodiment.

[0016] Figure 7A and Figure 7B Each illustration shows the shape of the conductor of the heater according to the second embodiment.

[0017] Figure 8A and Figure 8B The diagram illustrates the shape of the conductor of a heater according to another example of the first embodiment. Detailed Implementation

[0018] In the following description, modes for carrying out this disclosure will be described in detail and by way of example based on embodiments thereof with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc., of the components to be described in these embodiments will be appropriately varied depending on the configuration of the apparatus to which this disclosure is applied and various conditions. In other words, they are not intended to limit the scope of this disclosure to the following embodiments.

[0019] [First Embodiment]

[0020] Figure 1 This is a schematic cross-sectional view of an image forming apparatus 100 using electrophotographic recording technology. Examples of the image forming apparatus 100 include copiers and printers using electrophotographic or electrostatic recording methods. Figure 1 The image forming apparatus 100 shown in the figure is a laser printer that forms an image on a recording material P using an electrophotographic method.

[0021] The image forming apparatus 100 includes a video controller 120 and a control unit 113. The video controller 120, as an acquisition unit, receives and processes image information and printing instructions transmitted from an external device (such as a personal computer) to acquire information about an image to be formed on recording material P. The control unit 113 is connected to the video controller 120 and controls each unit constituting the image forming apparatus 100 according to instructions from the video controller 120. When the video controller 120 receives a printing instruction from the external device, it forms an image through the following operations.

[0022] When the image forming apparatus 100 receives a print signal, the scanner unit 21 emits laser light modulated according to the image information and scans the surface of the photosensitive drum 19, which is charged by the charging roller 16 and has a predetermined polarity. As a result, an electrostatic latent image is formed on the photosensitive drum 19. Toner is supplied to this electrostatic latent image from the developing roller 17, thereby developing the electrostatic latent image on the photosensitive drum 19 into a toner image (developer image). Meanwhile, the recording material (recording paper) P stacked in the sheet feed cassette 11 is fed one by one by the pickup roller 12 and conveyed by the transfer roller pair 13 toward the alignment roller pair 14. Furthermore, synchronized with the timing of the toner image on the photosensitive drum 19 reaching the transfer position defined by the photosensitive drum 19 and the transfer roller 20, the recording material P is conveyed from the alignment roller pair 14 to the transfer position. As the recording material P passes through the transfer position, the toner image on the photosensitive drum 19 is transferred onto the recording material P. Subsequently, the recording material P is heated by the fixing device (fixing unit) 200, which serves as an image heating apparatus (image heating unit), and the toner image is heated and fixed onto the recording material P. The recording material P, bearing the fixed toner image, is discharged via conveyor rollers 26 and 27 onto a tray provided in the upper part of the image forming apparatus 100. A drum cleaner 18 removes residual toner from the photosensitive drum 19. A sheet feed tray 28 (manual feed tray) is provided to support recording material P, even at non-standard sizes; the sheet feed tray 28 is a pair of recording material limiting plates with a width adjustable according to the size of the recording material P. Pickup rollers 29 feed the recording material P from the sheet feed tray 28. The image forming apparatus 100 includes a motor 30 that drives the fixing device 200, etc.

[0023] The control circuit 101, which is connected to the power control unit of the commercial AC power supply 102, supplies power to the fixing device 200. The aforementioned photosensitive drum 19, charging roller 16, scanner unit 21, developing roller 17, and transfer roller 20 constitute an image forming unit that forms an unfixed image on the recording material P. Furthermore, in this embodiment, the developing unit, including the photosensitive drum 19, charging roller 16, and developing roller 17, and the cleaning unit, including the drum cleaner 18, are configured as a processing cartridge 15 and detachably attached to the main body of the image forming apparatus 100. Additionally, the fixing device 200 is also configured to be detachably attached to the image forming apparatus 100.

[0024] Figure 2This is a cross-sectional view of the fixing apparatus 200 according to this embodiment. The fixing apparatus 200 includes a fixing film (hereinafter referred to as the film) 202 and a heater 203 disposed in a space inside the film 202 and in contact with the inner surface of the film 202. In addition, the fixing apparatus 200 includes a pressure roller (pressure member) 208 that forms a fixing clamping portion N together with the film 202 and the heater 203, and a metal support 204. A metal plate can be disposed between the heater 203 and the film 202.

[0025] Membrane 202 is a tubular heat-resistant membrane, also known as an annular belt or annular membrane, and its base layer is made of a heat-resistant resin such as polyimide or a metal such as stainless steel. Additionally, an elastic layer such as heat-resistant rubber may be provided on the surface of membrane 202. Pressure roller 208 includes a metal core 209 made of a material such as iron or aluminum, and an elastic layer 210 made of a material such as silicone rubber. Heater 203 is held by a retaining member 201 made of heat-resistant resin. The retaining member 201 also has a guiding function for guiding the rotation of membrane 202. A metal support 204 is provided to apply pressure from a spring (not shown) to the retaining member 201.

[0026] The pressure roller 208 rotates in the direction indicated by the arrow by receiving power from the motor 30. Due to the rotation of the pressure roller 208, the film 202 rotates accordingly. The recording material P, carrying the unfixed toner image, undergoes fixing treatment by heating while being held and conveyed at the fixing clamping section N.

[0027] Heater 203 includes heating elements (heating resistors) 203a and 203b provided on an elongated ceramic substrate 205. An overheating prevention device 211 is adjacent to heater 203. A glass layer (insulating layer) 212 is provided to ensure insulation between the heating elements 203a and 203b and the film 202. Examples of the overheating prevention device 211 include a thermal switch or thermal fuse, and in the event of abnormal heating of heater 203, the overheating prevention device 211 is actuated and blocks the power supply to heater 203. Glass layer 212 is a layer provided on heater 203.

[0028] Figure 3 This is a schematic diagram illustrating the electrical connection configuration of the heater 203 and the control circuit 101 according to this embodiment. Figure 3As illustrated, one AC terminal of the commercial AC power supply 102 is connected to connection portion C1 via relay 302 and bidirectional thyristor 303. Connection portion C1 connects to the fixing device 200 and control circuit 101. Connection portion C1 is electrically connected to the electrode portion (electrical contact) E1 of heater 203 via terminal T1. Terminal T1 is in contact with electrode portion E1. Another AC terminal of the commercial AC power supply 102 is connected to the electrode portion (electrical contact) E2 of heater 203 via relay 306, connection portion C2, and terminal T2. Terminal T2 is in contact with electrode portion E2. Therefore, the potential relationship between electrode portion E1 and electrode portion E2 is established as opposite polarities. Electrode portions E1 and E2 are positioned on one end LD1 side of the longitudinal direction LD of substrate 205. Terminal T1 is used to supply power to heating element 203a and to heating element 203b via heating element 203a. Terminal T2 is used to supply power to heating element 203b and, via heating element 203b, to heating element 203a. Power supplied to electrode portion E1 and power supplied to electrode portion E2 are respectively connected to heating elements 203a and 203b via conductor 304 on heater 203. Heating elements 203a and 203b are electrically connected via conductor 305. The area shown as shaded indicates glass layer 212 and protects the areas of conductor 304, heating elements 203a and 203b, and conductor 305 described above, in order to electrically insulate them from components other than heater 203. End LD2 is the opposite end of substrate 205 in the longitudinal direction LD.

[0029] Figures 4A to 4D Each of the illustrations shows a heater 400 according to the first embodiment, including conductors 401a, conductor 401b, etc. Figure 2 and Figure 3 The heater 203 shown in the diagram is replaced by a heater 400, which is similar to heater 203 and is used while connected to control circuit 101. Reference will be made to the following description. Figures 4A to 4D The mechanism described is to suppress leakage current flowing between conductors 401a and 401b via glass layer 212 by means of the shape of conductors 401a, conductor 401b, etc.

[0030] Figure 4AThis is a plan view of heater 400. Heater 400 includes a substrate 400SB. When heater 400 is viewed in a direction perpendicular to the plane of substrate 400SB, substrate 400SB includes a first long side 400SB1 and a second long side 400SB2. Heating elements 400a (first heating resistor) and 400b (second heating resistor) are deployed (printed) on substrate 400SB. Heating element 400a is deployed along the longitudinal direction LD of substrate 400SB. Additionally, heating element 400a is positioned at a location offset from the center SBC of substrate 400SB in the transverse direction SD of substrate 400SB towards the first long side 400SB1. Heating element 400b is deployed (printed) along the longitudinal direction LD of substrate 400SB. Additionally, heating element 400b is positioned offset from the center SBC of substrate 400SB in the transverse direction SD of substrate 400SB towards the second long side 400SB2. Electrode portion E1 (first electrical contact) is also deployed (printed) on substrate 400SB. Terminal T1, which supplies power to heating element 400a and, via heating element 400a, to heating element 400b, is in contact with electrode portion E1. Electrode portion E1 is located at a position LD1 in the longitudinal direction LD, closer to the end of substrate 400SB than heating element 400a, and is electrically connected to the end of heating element 400a in the longitudinal direction LD. Additionally, electrode portion E2 (second electrical contact) is also deployed (printed) on substrate 400SB. Terminal T2, which supplies power to heating element 400b and, via heating element 400b, to heating element 400a, is in contact with electrode portion E2. Electrode portion E2 is located at a position LD1 in the longitudinal direction LD, closer to the end of substrate 400SB than heating element 400b, and is electrically connected to the end of heating element 400b in the longitudinal direction LD. Furthermore, conductor 401a (first conductor) is deployed (printed) on substrate 400SB. Conductor 401a is disposed on the longitudinal direction LD between heating element 400a and electrode portion E1, and electrically connects heating element 400a and electrode portion E1. Additionally, conductor 401b (second conductor) is disposed (printed) on substrate 400SB. Conductor 401b is disposed on the longitudinal direction LD between heating element 400b and electrode portion E2, and electrically connects heating element 400b and electrode portion E2. Additionally, conductor 401c (third conductor) is disposed (printed) on substrate 400SB. Conductor 401c is electrically connected to the other end of heating element 400a opposite to one end of heating element 400a on the longitudinal direction LD, and to the other end of heating element 400b opposite to one end of heating element 400b on the longitudinal direction LD. Heating elements 400a and 400b are connected in series via conductor 401c. Furthermore, a glass layer (insulating layer) 404 is provided on substrate 400SB.With electrode portions E1 and E2 exposed, glass layer 404 covers heating element 400a, heating resistor 400b, conductors 401a, 401b, and 401c. Glass layer 404 is... Figure 4A The area is indicated as shaded. Electrode portions E1, E2, conductors 401a and 401b can be made of the same material, or different materials can be used as the materials for electrode portions E1 and E2, as well as conductors 401a and 401b. Furthermore, electrode portions E1 and E2 can be formed to have a greater thickness than conductors 401a and 401b (e.g., by being printed more times), thereby further enhancing their strength. The glass layer 404 does not necessarily completely cover conductors 401a and 401b. This will be described below. Figure 4B As illustrated, the glass layer 404 of the heater 400 does not cover the corresponding connection portions of conductors 401a and 401b with electrode portions E1 and E2. Instead, the glass layer 404 may be deployed to cover a portion of electrode portions E1 and E2.

[0031] Furthermore, electrode portion E2 is positioned at a different location in the longitudinal direction LD than electrode portion E1. In the case of heater 400, electrode E2 is positioned at an end LD1 in the longitudinal direction LD that is further away from the substrate 400SB than electrode E1. Additionally, the positions of electrode portion E1 and electrode portion E2 overlap in the transverse direction SD. Figure 4B The diagram illustrates the process of... Figure 4A The magnified view of area 401 indicated by the dotted lines. Figure 4C and Figure 4D yes Figure 4B The variant example, and Figure 4E This is a reference example.

[0032] Figure 4B One example illustrating the shapes of conductors 401a and 401b is shown. Figure 4B In each of conductors 401a and 401b shown in the diagram, the width of the conductor on dashed line A is narrower than the width of the conductor on dashed line B, and the conductor width increases continuously from dashed line A to dashed line B. Dashed line A indicates the connection position of conductor 401a to heating element 400a (first connection position) and the connection position of conductor 401b to heating element 400b (second connection position). Dashed line B indicates the boundary between region AX and region AY, which will be described below. Dashed line H indicates the ends of regions AX1 and AX2 in the longitudinal direction LD. Dashed line J indicates the end of conductor 401a in the longitudinal direction LD. Dashed line K indicates the end of conductor 401b in the longitudinal direction LD.

[0033] A widened portion AX1 (first widened portion) of conductor 401a is provided in region AX of conductor 401a, on the side of end LD1 closer to substrate 400SB than the first connection position between conductor 401a and heating element 400a. The widened portion AX1 of conductor 401a is wider in the lateral direction SD than the width of the first connection position in the lateral direction SD. Similarly, a widened portion AX2 (second widened portion) of conductor 401b is provided in region AX of conductor 401b, on the side of end LD1 closer to substrate 400SB than the second connection position between conductor 401b and heating element 400b. The widened portion AX2 of conductor 401b is wider in the lateral direction SD than the width of the second connection position in the lateral direction SD.

[0034] A first width-changing portion AY1 is provided in the region AY of conductor 401a between the widened portion AX1 and the first connection position in the longitudinal direction LD. In the transverse direction SD, the width of the first width-changing portion AY1 decreases from the widened portion AX1 towards the first connection position. A second width-changing portion AY2 is provided in the region AY of conductor 401b between the widened portion AX2 and the second connection position in the longitudinal direction LD. In the transverse direction SD, the width of the second width-changing portion AY2 decreases from the widened portion AX2 towards the second connection position.

[0035] The first long side 401aL of the first width-changing portion AY1 facing the substrate 400SB has a linear shape parallel to the first long side 400SB1. The second long side 401bL of the second width-changing portion AY2 facing the substrate 400SB has a linear shape parallel to the second long side 400SB2. Due to this shape, the heating element 400a and the heating element 400b can be deployed close to the first long side 400SB1 and the second long side 400SB2 of the substrate 400SB, respectively. This can help reduce the thermal stress applied to the substrate 400SB when the heating element 400a and the heating element 400b generate heat. In particular, this shape is effective when the material of the substrate 400SB is ceramic. Figure 4B In the example shown in the figure, the side of conductor 401a facing the first long side 400SB1 generally (from dashed line A to dashed line J) has a linear shape parallel to the first long side 400SB1, and the side of conductor 401b facing the second long side 400SB2 generally (from dashed line A to dashed line K) has a linear shape parallel to the second long side 400SB2.

[0036] In the lateral direction SD, the distance LE1 between the first connection position and the second connection position is longer than the distance LE2 between the widened portion AX1 and the widened portion AX2. In the lateral direction SD, the distance between the first conductor 401a and the conductor 401b gradually increases from the first widened portion AX1 toward the first connection position.

[0037] When the temperatures of heating elements 400a and 400b increase, the temperature of the glass layer 404 located near heating elements 400a and 400b also increases. Glass tends to decrease its resistance as temperature increases. On the other hand, due to the distance between the glass and heating elements 400a and 400b, the temperature of the glass on dashed line B increases less compared to the temperature near dashed line A.

[0038] In other words, the glass on dashed line B is expected to have a higher resistance than that on dashed line A. Therefore, on dashed line A, this embodiment reduces the conductor widths of conductors 401a and 401b, thereby increasing the distance between the conductors in the lateral direction SD of the substrate, thus increasing the resistance of the glass between the conductors to suppress leakage current. On the other hand, since leakage current due to temperature rise is unlikely to occur on dashed line B, this embodiment increases the conductor width, thereby reducing the resistance between conductors 401a and 402b.

[0039] Then, as Figure 8A and Figure 8B As illustrated in the diagram, the heater 400 can be configured such that a widened portion AX1 and a width-changing portion AY1 are provided only in one of the two conductors. Figure 8A In the conductor 408b, the widened portion AX1 and the width-changing portion AY1 are included, and in the conductor 408a, the width-constant portion ST maintains a constant width in the transverse direction SD. Conversely, in Figure 8B In the middle, conductor 408a includes a widening portion AX1 and a width changing portion AY1, and conductor 408b includes a width constant portion ST that maintains a constant width in the transverse direction SD.

[0040] Figure 4C Another example of a conductor shape is illustrated. (Compared to...) Figure 4B The example shown in the diagram is similar. Figure 4C In the diagram, the width between conductors 405a and 405b on dashed line A is wider than the width between conductors on dashed line B. The widths of conductors 405a and 405b remain constant in all regions between dashed lines A and B (first constant width portion and second constant width portion).

[0041] Figure 4D Another example of a conductor shape is illustrated. (Compared to...) Figure 4B and Figure 4C The example shown in the diagram is similar. Figure 4D In the diagram, the width between conductors 406a and 406b along dashed line A is wider than the width between them along dashed line B. Furthermore, the widths of conductors 406a and 406b change at position C, located between dashed lines A and B. Figure 4D In the example shown in the diagram, the point of change in conductor width between dashed lines A and B is located only at one location on dashed line C, but it can be provided at multiple locations. Figure 4D In the example shown in the diagram, the distance between conductors 406a and 406b in the lateral direction SD increases in a stepped manner from the widened portion corresponding to region AX toward the connection location.

[0042] Figure 4E A reference example of a conductor shape is illustrated. (Compared to...) Figure 4B , Figure 4C and Figure 4D The example shown in the diagram is similar. Figure 4E The width between conductors 407a and 407b on dashed line A in the diagram is also wider than the width between conductors on dashed line B. Figure 4E On both sides of the conductor shown in the diagram, the conductor width can be from Figure 4E The dashed line B in the diagram begins to change in a step-like manner, but this is not shown here.

[0043] In this way, such as Figures 4B to 4D The conductor shaping illustrated in the diagram can reduce the conductor's resistance while suppressing leakage current between opposite electrodes near the heating element. Additionally, it can reduce the thermal stress applied to the 400SB substrate.

[0044] Figures 5A to 5D The diagram shows... Figure 2 The fixing device 200 shown in the figure and having Figures 4A to 4E The heater 400 is illustrated in the diagram with the shape of a conductor. Reference will be made to it in the following description. Figures 5A to 5D Describe the positional relationship between the point where the conductor width changes and the interior of the fixing device 200.

[0045] Figure 5A In the diagram, the dashed line E indicates the position of the end of the film 202, and the dashed line F indicates the position of the end of the pressure roller 208. For example, due to component tolerances, the orientation of the recording material P during the fixing process, and the position of the fixing clamping portion N in the longitudinal direction LD through which the recording material P passes, the film 202 shifts to one side in the longitudinal direction LD while rotating. Figure 5A The position of the dashed line E in the diagram is where membrane 202 is located. Figure 5A The position when the center shifts to the left to the maximum extent.

[0046] Figure 5B The diagram includes Figure 4B The heater 400 of conductors 401a and 401b shown in the figure, and Figure 4B The dashed line B in the middle and Figures 5A to 5D The position of the dashed line F corresponds to this. Considering the temperature rise in the pressure roller 208, Figure 5B The example shown in the middle diagram suppresses leakage current by changing the conductor width from heating element 400a and heating element 400b to the dashed line F. Figures 4A to 4E The dashed line B in Figure 5 and the dashed line F in Figure 5 are in Figures 5A to 5D The alignment is correct, but the dashed line B can be located on the electrode side relative to the dashed line F. In other words, one end F of the pressure roller 208 in the longitudinal direction LD can be located on the boundary between the first widening portion AX1 and the first width changing portion AY1, or within the region of the first width changing portion AY1. Temperature rises in the region where the pressure roller 208 is held together with the heater 400 via the membrane 202 (fixing clamping portion N), therefore, a long distance between the conductors is desirable in this region where the expected temperature rise is expected.

[0047] Figure 5C The diagram includes Figure 4C The heater 400 of conductors 405a and 405b shown in the diagram, and Figures 4A to 4E The dashed line B in the middle and Figures 5A to 5D The position of the dashed line E corresponds to this. Considering the temperature rise in membrane 202 caused by thermal conduction, Figure 5C The example shown in the diagram decreases the conductor width (i.e., increases the distance between conductors) from heating elements 400a and 400b to the dashed line E. Figures 4A to 4E The dashed line B in the middle and Figures 5A to 5D The dashed line E in Figures 5A to 5D The center is aligned, but dashed line B can be located on the electrode side relative to dashed line E.

[0048] Figure 5D The diagram includes Figure 4D The heater 400 for conductors 406a and 406b shown in the diagram, and Figures 4A to 4E The dashed line B in the middle and Figure 4D The dashed line C in the middle is respectively with Figures 5A to 5D The position of the dashed line E in the middle and Figures 5A to 5D The position of the dashed line F corresponds to this. Considering the temperature rise in membrane 202 and pressure roller 208, Figure 5D The example shown in the diagram alters the conductor widths of conductors 406a and 406b according to the position of the ends of each component. Figure 5D middle, Figure 4D The position of the dashed line C in the diagram can be located on the electrode side (closer to the position of the dashed line B).

[0049] In this way, this embodiment changes the conductor width according to the position of the components inside the fixing device 200, thereby reducing the conductor resistance while suppressing leakage current between opposing electrodes.

[0050] [Second Embodiment]

[0051] Reference Figure 6 as well as Figure 7A and Figure 7B The heater 600 according to the second embodiment is described. Figure 6 The diagram illustrates the electrical connection configuration of the fixing device 601 and the control circuit 602 according to this embodiment. Figure 6 The illustration shows a plan view of heater 600. It is assumed that parts not specifically described in this embodiment are similar to those in the first embodiment.

[0052] like Figure 6 As illustrated, one AC terminal of the commercial AC power supply 102 is connected via a relay 603 to each of the bidirectional thyristors 604 and 605. Additionally, the commercial AC power supply 102 is connected to connection portions C3 and C4, which in turn connect the fixing device 601 and the control circuit 602. In the fixing device 601, connection portions C3 and C4 are connected via a connection similar to... Figure 3 Terminals T1 and T2 (not shown) in the diagram are electrically connected to electrode portions E3 (third electrical contact) and E4 (first electrical contact) of heater 600, respectively. Another AC terminal of commercial AC power supply 102 is connected via connection portion C5 to electrode portion E5 (second electrical contact) of heater 600 in fixing device 601 via a terminal (not shown) that contacts electrode E5. Therefore, the potential relationship between E3 / E4 and E5 is established as opposite polarities. Power supplied to E3 and power supplied to E4 are connected to heating elements 600a (third heating resistor) and 600b (first heating resistor) via conductors 606a (fourth conductor) and 606b (first conductor) on heater 600, respectively. Power supplied to E5 is connected to heating elements 600c (second heating resistor) and 600d (fourth heating resistor) via conductor 606c (second conductor). Heating elements 600a and 600d are electrically connected via conductor 607 (the fifth conductor). Heating elements 600b and 600c are electrically connected via conductor 608 (the third conductor). Similar to... Figure 3The heater 600 includes a glass layer and is configured to be electrically insulated from components other than the heater 600, but this is omitted here. Heating elements 600a to 600d have a tapered shape to suppress temperature rise at the ends of the heater 600 where the recording material P does not pass when printing on small-sized paper. Heating elements 600a and 600d each have a wide heating element width at their ends in the longitudinal direction LD and a narrow heating element width at their center. Heating elements 600b and 600c each have a narrow heating element width at their ends in the longitudinal direction LD and a wide heating element width at their center. The heat distribution of the heater 600 in the longitudinal direction LD is controlled by using bidirectional silicon controlled rectifiers 604 and 605 to control the heat ratio between the group of heating elements 600a and 600d and the group of heating elements 600b and 600c.

[0053] In this manner, in addition to the heater 400 described in the first embodiment, the heater 600 also has the following configuration: A heating element 600a (third heating resistor) is deployed on the substrate 600SB along the longitudinal direction LD. Compared to the heating element 600b (first heating resistor), the heating element 600a is positioned at a location offset more from the center SBC in the transverse direction SD towards the first long side 600SB1. A heating element 600d (fourth heating resistor) is deployed on the substrate 600SB along the longitudinal direction LD. Compared to the heating element 600c (second heating resistor), the heating element 600d is positioned at a location offset more from the center SBC in the transverse direction SD towards the second long side 600SB2.

[0054] Additionally, electrode E3 (third electrical contact) is disposed on substrate 600. A third terminal for supplying power to heating element 600a (third heating resistor) and, via heating element 600a, to heating element 600d (fourth heating resistor) is in contact with electrode E3. Electrode E3 is positioned in the longitudinal direction LD at one end of substrate 600 closer to heating element 600a than heating element 600a, and is electrically connected to one end of heating element 600a in the longitudinal direction LD. Furthermore, conductor 606a (fourth conductor) is disposed on substrate 600. Conductor 606a is disposed in the longitudinal direction LD between heating element 600a and electrode E3, and electrically connects heating element 600a and electrode E3. Additionally, conductor 607 (fifth conductor) is disposed on substrate 600. Conductor 607 is electrically connected to the other end of heating element 600a, which is opposite to one end of heating element 600a in the longitudinal direction LD, and to the other end of heating element 600d, which is opposite to one end of heating element 600d in the longitudinal direction LD.

[0055] Heating element 600d (fourth heating resistor) is electrically connected to electrode E5 (second electrical contact) via conductor 606c (second conductor). Heating elements 600a and 600d are connected in series via conductor 607 (fifth conductor). Electrode E3 is positioned in the longitudinal direction LD at one end LD1 of the substrate 600SB, closer to electrode E4 (first electrical contact) than electrode E4 (first electrical contact). The position of electrode E3 overlaps with the positions of electrodes E4 and E5 in the transverse direction SD.

[0056] Figure 7A and Figure 7B The diagram illustrates conductors 700a to 700c, etc., of the heater 600 according to the second embodiment. Figure 7A and Figure 7B The substrate and glass layer are omitted. Additionally, Figure 6 In the diagram, conductors 606a, 606b, and 606c are replaced with conductors 700a, 700b, and 700c, or conductors 701a, 701b, and 701c. A mechanism using these conductors to suppress leakage current flowing between conductors 700b and 700c will be described.

[0057] Figure 7A An example of conductor shapes 700a to 700c according to the second embodiment is illustrated. Regarding... Figure 7A In the diagram, conductor 700b (the first conductor) is narrower on dashed line A than on dashed line B. Furthermore, the conductor width gradually increases from dashed line A to dashed line B. Because conductors 700a and 700b have the same polarity and no leakage current is generated between them, the distance between them remains constant. Figure 7A In the conductor 700b, a widened portion AX1 is included in region AX, and a width-changing portion AY1 is included in region AY. Conductor 700c includes a width-constant portion ST in region AY that maintains a constant width in the transverse direction SD. Conductor 700a (the fourth conductor) also includes a width-constant portion ST in region AY.

[0058] Figure 7B Another example of a conductor shape is illustrated. About Figure 7B In the diagram, conductors 701b and 701c are shown, with the conductor's width along dashed line A being narrower than its width along dashed line B. Furthermore, the conductor width gradually increases from dashed line A to dashed line B. Figure 7B In, with Figure 7A In comparison, conductor 701c has a wider conductor width, thereby reducing its resistance. Figure 7BIn the conductor 701b, the widened portion AX1 is included in region AX and the width-changing portion AY1 is included in region AY. Conductor 701c includes the widened portion AX1 in region AX and the width-changing portion AY1 in region AY. Conductor 701a (the fourth conductor) also includes a constant-width portion ST in region AY.

[0059] In this way, such as Figure 7A and Figure 7B The conductor shaping shown in the diagram can reduce the conductor's resistance while suppressing leakage current between opposite polarities near the heating element.

[0060] While this disclosure has been described with reference to embodiments, it should be understood that this disclosure is not limited to the disclosed embodiments. The scope of the following claims should be given the broadest interpretation to cover all such modifications and equivalent structures and functions.

Claims

1. A heater, comprising: An elongated substrate, which has a first long side and a second long side when the heater is viewed in a direction perpendicular to the plane of the substrate; The first heating resistor is deployed on the substrate along the longitudinal direction of the substrate and is located at a position offset from the center of the substrate in the transverse direction of the substrate toward the first long side. The second heating resistor is deployed on the substrate along the longitudinal direction and is positioned offset from the center in the transverse direction toward the second long side. A first electrical contact is in contact with a first terminal, the first terminal is used to supply power to the first heating resistor and to supply power to the second heating resistor via the first heating resistor, the first electrical contact is arranged at a position closer to one end of the substrate in the longitudinal direction than the first heating resistor, and the first electrical contact is electrically connected to one end of the first heating resistor in the longitudinal direction. The second electrical contact contacts the second terminal, which is used to supply power to the second heating resistor and to supply power to the first heating resistor via the second heating resistor. The second electrical contact is arranged at one end of the substrate closer to the second heating resistor in the longitudinal direction, and the second electrical contact is electrically connected to one end of the second heating resistor in the longitudinal direction. A first conductor is positioned in the longitudinal direction between the first heating resistor and the first electrical contact, and the first conductor is electrically connected to the first heating resistor and the first electrical contact. A second conductor is disposed in the longitudinal direction between the second heating resistor and the second electrical contact, and the second conductor is electrically connected to the second heating resistor and the second electrical contact; A third conductor is electrically connected to the other end of the first heating resistor, which is opposite to one end of the first heating resistor in the longitudinal direction, and to the other end of the second heating resistor, which is opposite to one end of the second heating resistor in the longitudinal direction. as well as An insulating layer, in the case that the first electrical contact and the second electrical contact are exposed, covers the first heating resistor, the second heating resistor, the first conductor, the second conductor, and the third conductor. The first heating resistor and the second heating resistor are connected in series via the third conductor. The second electrical contact is located at one end of the substrate further away from the first electrical contact in the longitudinal direction. The positions of the first electrical contact and the second electrical contact overlap in the lateral direction. The first widening portion is disposed in the region of the first conductor on one side closer to the substrate than the first connection position of the first conductor and the first heating resistor. The width of the first widening portion in the lateral direction is wider than the width of the first connection position in the lateral direction. The second widening portion is disposed in the region of the second conductor on one end closer to the substrate than the second connection position of the second conductor and the second heating resistor. The width of the second widening portion in the lateral direction is wider than the width of the second connection position in the lateral direction. A first width-changing portion is disposed in the region of the first conductor between the first widened portion and the first connection position in the longitudinal direction, and the first width-changing portion has a width that decreases from the first widened portion toward the first connection position in the transverse direction. The second width-changing portion is disposed in the region of the second conductor between the second widening portion and the second connection position in the longitudinal direction, and the second width-changing portion has a width that decreases from the second widening portion toward the second connection position in the transverse direction. The first long side of the first width-changing portion facing the substrate has a linear shape parallel to the first long side. The second long side of the second width-changing portion facing the substrate has a linear shape parallel to the second long side, and In the lateral direction, the distance between the first connection position and the second connection position is longer than the distance between the first widened portion and the second widened portion.

2. The heater according to claim 1, wherein the distance between the first conductor and the second conductor in the transverse direction gradually increases from the first widened portion toward the first connection position.

3. The heater of claim 1, wherein the distance between the first conductor and the second conductor in the transverse direction increases in a stepped manner from the first widened portion toward the first connection position.

4. The heater according to claim 1, wherein the side of the first conductor facing the first long side is generally in a linear shape parallel to the first long side, and the side of the second conductor facing the second long side is generally in a linear shape parallel to the second long side.

5. The heater according to claim 1, wherein the insulating layer is a glass layer.

6. The heater according to claim 1, further comprising: A third heating resistor is deployed on the substrate along the longitudinal direction, and the third heating resistor is arranged at a position offset more than the first heating resistor in the direction from the center in the transverse direction toward the first long side. A fourth heating resistor is disposed on the substrate along the longitudinal direction, and the fourth heating resistor is arranged at a position offset more than the second heating resistor in the direction from the center in the transverse direction toward the second long side. The third electrical contact is in contact with the third terminal, which is used to supply power to the third heating resistor and to supply power to the fourth heating resistor via the third heating resistor. The third electrical contact is arranged at a position in the longitudinal direction closer to the substrate than the third heating resistor, and the third electrical contact is electrically connected to the end of the third heating resistor in the longitudinal direction. A fourth conductor is disposed in the longitudinal direction between the third heating resistor and the third electrical contact, and the fourth conductor is electrically connected to the third heating resistor and the third electrical contact; as well as The fifth conductor is electrically connected to the other end of the third heating resistor, which is opposite to one end of the third heating resistor in the longitudinal direction, and to the other end of the fourth heating resistor, which is opposite to one end of the fourth heating resistor in the longitudinal direction. The fourth heating resistor is electrically connected to the second electrical contact via the second conductor. The third heating resistor and the fourth heating resistor are connected in series via the fifth conductor. The third electrical contact is positioned in the longitudinal direction closer to one end of the substrate than the first electrical contact, and The position of the third electrical contact overlaps with the positions of the first electrical contact and the second electrical contact in the lateral direction.

7. The heater of claim 6, wherein the region of the fourth conductor located at the same position in the longitudinal direction as the first width-changing portion of the first conductor has a constant width in the transverse direction.

8. An image heating device configured to heat an image formed on a recording material, the image heating device comprising: A tubular membrane configured to rotate in contact with the recording material; The heater according to claim 1, wherein the heater is deployed in the space inside the membrane; A roller forming a clamping portion, the roller being configured to clamp recording material together with the heater via the membrane; First terminal; as well as Second terminal.

9. The heater of claim 8, wherein, in the longitudinal direction, one end of the roller is located at the boundary between the first widened portion and the first width-changing portion or in the region of the first width-changing portion.

10. An image heating device configured to heat an image formed on a recording material, the image heating device comprising: A tubular membrane configured to rotate in contact with the recording material; The heater according to claim 6, wherein the heater is deployed in the space inside the membrane; A roller forming a clamping portion, the roller being configured to clamp recording material together with the heater via the membrane; First terminal; Second terminal; as well as Third terminal.

11. The heater of claim 10, wherein in the longitudinal direction, one end of the roller is located at the boundary between the first widening portion and the first width-changing portion or in the region of the first width-changing portion.

12. A heater, comprising: An elongated substrate, which has a first long side and a second long side when the heater is viewed in a direction perpendicular to the plane of the substrate; The first heating resistor is deployed on the substrate along the longitudinal direction of the substrate and is located at a position offset from the center of the substrate in the transverse direction of the substrate toward the first long side. The second heating resistor is deployed on the substrate along the longitudinal direction and is positioned offset from the center in the transverse direction toward the second long side. A first electrical contact is in contact with a first terminal, the first terminal is used to supply power to the first heating resistor and to supply power to the second heating resistor via the first heating resistor, the first electrical contact is arranged at a position closer to one end of the substrate in the longitudinal direction than the first heating resistor, and the first electrical contact is electrically connected to one end of the first heating resistor in the longitudinal direction. The second electrical contact contacts the second terminal, which is used to supply power to the second heating resistor and to supply power to the first heating resistor via the second heating resistor. The second electrical contact is arranged at one end of the substrate closer to the second heating resistor in the longitudinal direction, and the second electrical contact is electrically connected to one end of the second heating resistor in the longitudinal direction. A first conductor is disposed in the longitudinal direction between the first heating resistor and the first electrical contact, and the first conductor is electrically connected to the first heating resistor and the first electrical contact. A second conductor is disposed in the longitudinal direction between the second heating resistor and the second electrical contact, and the second conductor is electrically connected to the second heating resistor and the second electrical contact; A third conductor is electrically connected to the other end of the first heating resistor, which is opposite to one end of the first heating resistor in the longitudinal direction, and to the other end of the second heating resistor, which is opposite to one end of the second heating resistor in the longitudinal direction. as well as An insulating layer, in the case that the first electrical contact and the second electrical contact are exposed, covers the first heating resistor, the second heating resistor, the first conductor, the second conductor, and the third conductor. The first heating resistor and the second heating resistor are connected in series via the third conductor. The second electrical contact is arranged at a position in the longitudinal direction that is different from the position of the first electrical contact. The positions of the first electrical contact and the second electrical contact overlap in the lateral direction. The widened portion is disposed in the region of the first conductor on one side closer to the substrate than the connection position between the first conductor and the first heating resistor, and the width of the widened portion in the lateral direction is wider than the width of the connection position in the lateral direction. A width-changing portion is disposed in the region of the first conductor between the widened portion and the connection position in the longitudinal direction, and the width-changing portion has a width that decreases from the widened portion toward the connection position in the transverse direction. The first long side of the portion with the changed width facing the substrate has a linear shape parallel to the first long side. The second conductor, on its second long side facing the substrate and located in the same region along the longitudinal direction as the width change portion, has a linear shape parallel to the second long side. In the lateral direction, the distance between the connection point of the first conductor and the first heating resistor and the connection point of the second conductor and the second heating resistor is longer than the distance between the widened portion and the region of the second conductor located at the same position as the widened portion in the longitudinal direction.

13. The heater of claim 12, wherein the side of the first conductor facing the first long side is generally in a linear shape parallel to the first long side, and the side of the second conductor facing the second long side is generally in a linear shape parallel to the second long side.

14. The heater of claim 12, wherein the second electrical contact is disposed at a position in the longitudinal direction further away from one end of the substrate than the first electrical contact.

15. The heater of claim 12, wherein the first electrical contact is arranged at a position in the longitudinal direction further away from one end of the substrate than the second electrical contact.

16. The heater of claim 12, wherein the insulating layer is a glass layer.

17. The heater according to claim 12, further comprising: A third heating resistor is deployed on the substrate along the longitudinal direction, and the third heating resistor is arranged at a position offset more than the first heating resistor in the direction from the center in the transverse direction toward the first long side. A fourth heating resistor is disposed on the substrate along the longitudinal direction, and the fourth heating resistor is arranged at a position offset more than the second heating resistor in the direction from the center in the transverse direction toward the second long side. The third electrical contact is in contact with the third terminal, which is used to supply power to the third heating resistor and to supply power to the fourth heating resistor via the third heating resistor. The third electrical contact is arranged at a position in the longitudinal direction closer to the substrate than the third heating resistor, and the third electrical contact is electrically connected to the end of the third heating resistor in the longitudinal direction. A fourth conductor is disposed in the longitudinal direction between the third heating resistor and the third electrical contact, and the fourth conductor is electrically connected to the third heating resistor and the third electrical contact; as well as The fifth conductor is electrically connected to the other end of the third heating resistor, which is opposite to one end of the third heating resistor in the longitudinal direction, and to the other end of the fourth heating resistor, which is opposite to one end of the fourth heating resistor in the longitudinal direction. The fourth heating resistor is electrically connected to the second electrical contact via the second conductor. The third heating resistor and the fourth heating resistor are connected in series via the fifth conductor. The third electrical contact is arranged at a position in the longitudinal direction that differs from the positions of the first and second electrical contacts, and The position of the third electrical contact overlaps with the positions of the first electrical contact and the second electrical contact in the lateral direction.

18. The heater of claim 17, wherein the region of the fourth conductor located at the same position in the longitudinal direction as the width-changing portion of the first conductor has a constant width in the transverse direction.

19. A heater, comprising: An elongated substrate, which has a first long side and a second long side when the heater is viewed in a direction perpendicular to the plane of the substrate; The first heating resistor is deployed on the substrate along the longitudinal direction of the substrate and is located at a position offset from the center of the substrate in the transverse direction of the substrate toward the first long side. The second heating resistor is deployed on the substrate along the longitudinal direction and is positioned offset from the center in the transverse direction toward the second long side. A first electrical contact is in contact with a first terminal, the first terminal is used to supply power to the first heating resistor and to supply power to the second heating resistor via the first heating resistor, the first electrical contact is arranged at a position closer to one end of the substrate in the longitudinal direction than the first heating resistor, and the first electrical contact is electrically connected to one end of the first heating resistor in the longitudinal direction. The second electrical contact contacts the second terminal, which is used to supply power to the second heating resistor and to supply power to the first heating resistor via the second heating resistor. The second electrical contact is arranged at one end of the substrate closer to the second heating resistor in the longitudinal direction, and the second electrical contact is electrically connected to one end of the second heating resistor in the longitudinal direction. A first conductor is disposed in the longitudinal direction between the first heating resistor and the first electrical contact, and the first conductor is electrically connected to the first heating resistor and the first electrical contact. A second conductor is disposed in the longitudinal direction between the second heating resistor and the second electrical contact, and the second conductor is electrically connected to the second heating resistor and the second electrical contact; A third conductor is electrically connected to the other end of the first heating resistor, which is opposite to one end of the first heating resistor in the longitudinal direction, and to the other end of the second heating resistor, which is opposite to one end of the second heating resistor in the longitudinal direction. as well as An insulating layer, in the case that the first electrical contact and the second electrical contact are exposed, covers the first heating resistor, the second heating resistor, the first conductor, the second conductor, and the third conductor. The first heating resistor and the second heating resistor are connected in series via the third conductor. The second electrical contact is located at one end of the substrate further away from the first electrical contact in the longitudinal direction. The positions of the first electrical contact and the second electrical contact overlap in the lateral direction. The first widening portion is disposed in the region of the first conductor on one side closer to the substrate than the first connection position of the first conductor and the first heating resistor. The width of the first widening portion in the lateral direction is wider than the width of the first connection position in the lateral direction. The second widening portion is disposed in the region of the second conductor on one end closer to the substrate than the second connection position of the second conductor and the second heating resistor. The width of the second widening portion in the lateral direction is wider than the width of the second connection position in the lateral direction. A first constant-width portion is disposed in all regions of the first conductor between the first widened portion and the first connection position in the longitudinal direction, and the first constant-width portion has a constant width in the transverse direction. The second constant-width portion is disposed in all regions of the second conductor between the second widened portion and the second connection position in the longitudinal direction, and the second constant-width portion has a constant width in the transverse direction. The first long side of the first constant-width portion facing the substrate has a linear shape parallel to the first long side. The second long side of the second constant-width portion facing the substrate has a linear shape parallel to the second long side, and In the lateral direction, the distance between the first connection position and the second connection position is longer than the distance between the first widened portion and the second widened portion.

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