Heater unit, fixing device, and image forming apparatus

Abstract

The present application provides a small heater unit, a fixing device, and an image forming apparatus. The heater unit of an embodiment has a substrate, a first heat generating portion, a first wiring portion, a first electrode portion, a second heat generating portion, a second wiring portion, and a second electrode portion. The first heat generating portion is provided on a first surface side of the substrate. The first wiring portion is provided on the first surface side of the substrate and is connected to the first heat generating portion. The first electrode portion is provided on the first surface side of the substrate and supplies electric power to the first heat generating portion via the first wiring portion. The second heat generating portion is provided on a second surface side of the substrate opposite to the first surface. The second wiring portion is provided on the second surface side of the substrate and is connected to the second heat generating portion. The second electrode portion is provided on the second surface side of the substrate and supplies electric power to the second heat generating portion via the second wiring portion.

Description

Technical Field

[0001] Embodiments of the present invention relate to a heater unit, a fixing device, and an image forming apparatus. Background Technology

[0002] Currently, electrophotographic image forming apparatuses include fixing devices that heat toner and fix it onto a sheet. Among these fixing devices, there are heater units with multiple heating elements arranged along the width of the sheet on a substrate. In these fixing devices, multiple wirings for supplying power to the multiple heating elements need to be formed on the substrate, resulting in a problem of increasing the size of the heater unit and thus making the fixing device larger. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a miniaturized heater unit, fixing device, and image forming device.

[0004] The heater unit of the embodiment includes: a substrate; a first heating element disposed on a first surface of the substrate; a first wiring portion disposed on the first surface of the substrate and connected to the first heating element; a first electrode portion disposed on the first surface of the substrate and supplying power to the first heating element via the first wiring portion; a second heating element disposed on a second surface of the substrate opposite to the first surface; a second wiring portion disposed on the second surface of the substrate and connected to the second heating element; and a second electrode portion disposed on the second surface of the substrate and supplying power to the second heating element via the second wiring portion. Attached Figure Description

[0005] Figure 1 This is a front view showing the overall configuration of the image forming apparatus according to the first embodiment.

[0006] Figure 2 This is a diagram illustrating a specific example of the hardware configuration of an image forming apparatus.

[0007] Figure 3 This is a cross-sectional view of the fixing device viewed from the long side.

[0008] Figure 4 This is a top view of the heater unit.

[0009] Figure 5 This is a bottom view of the heater unit.

[0010] Figure 6 This is a cross-sectional view of the heater unit.

[0011] Figure 7 This is a top view of the first temperature sensing component and the thermostat section.

[0012] Figure 8 This is a circuit diagram of the fixing device.

[0013] Figure 9 This is a top view of the heater unit according to the second embodiment.

[0014] Figure 10 This is a bottom view of the heater unit according to the second embodiment.

[0015] Figure 11 This is a top view of the heater unit according to the third embodiment.

[0016] Figure 12 This is a bottom view of the heater unit according to the third embodiment.

[0017] Figure 13 This is a top view of the heater unit according to the fourth embodiment.

[0018] Figure 14 This is a bottom view of the heater unit according to the fourth embodiment.

[0019] Explanation of reference numerals in the attached figures

[0020] 1…image forming apparatus, 30…fixing apparatus, 43, 243, 343, 443…heater unit, 50…substrate, 501…first surface, 71, 371, 471…first heating element, 72, 372…second heating element, 81, 181…first electrode element, 82, 182…second electrode element, 83, 183…first wiring element, 84…second wiring element, 502…second surface, Wa, Wb…width. Detailed Implementation

[0021] Hereinafter, the heater unit, fixing device, and image forming apparatus of the embodiments will be described with reference to the accompanying drawings. In the following drawings, unless otherwise specified, the same or equivalent components will be labeled with the same reference numerals.

[0022] (First Implementation)

[0023] Figure 1 This is a front view showing the overall configuration of the image forming apparatus according to the embodiment. For example, the image forming apparatus 1 is a multifunction printer (MFP). However, the image forming apparatus 1 is not limited to the above example, and may also be a copier or printer, etc.

[0024] like Figure 1 As shown, the image forming apparatus 1 includes a housing 11, a scanner unit 12, a sheet supply unit 13, a printer unit 14, a paper output unit 15, and a control panel 16.

[0025] The housing 11 forms the outline of the image forming apparatus 1. The housing 11 houses the scanner section 12, the sheet supply section 13, and the printer section 14.

[0026] The scanner unit 12 reads the image of the object to be read by varying the brightness of light. The scanner unit 12 generates and records image information representing the read image. The scanner unit 12 outputs the generated image information to the printer unit 14. Furthermore, the recorded image information can also be transmitted to external devices, etc., via a network.

[0027] The sheet supply unit 13 supplies sheets S, such as paper, as sheet-like recording media to the transport path 24 one by one, according to the timing when the toner image is formed by the printer unit 14. The sheet supply unit 13 has a paper tray 130 for storing the sheets S. The sheet supply unit 13 supplies a specified sheet S from the paper tray 130 to the transport path 24 according to instructions from the control unit 17.

[0028] The printer unit 14 forms a toner image on the sheet S conveyed by the sheet supply unit 13. Based on image information obtained from the scanner unit 12 or an external device, the printer unit 14 uses a recording agent such as toner to form a toner image on the sheet S as an output image.

[0029] In this embodiment, for ease of explanation, the printer unit 14 using an intermediate transfer method will be used as an example. However, the configuration of this embodiment can also be applied to an image forming apparatus having an image forming unit using a direct transfer method. The printer unit 14 includes an intermediate transfer unit 21, a secondary transfer unit 22, a fixing device 30, and a transport path 24.

[0030] The intermediate transfer section 21 includes an intermediate transfer belt 31, multiple rollers 321, 322, 323, 324, and multiple image forming sections GY, GM, GC, GK.

[0031] The intermediate transfer belt 31 is formed in a ring shape. Multiple rollers 321, 322, 323, and 324 support the intermediate transfer belt 31. Therefore, the intermediate transfer belt 31 can move along... Figure 1 The arrow m in the image indicates a circular movement.

[0032] Multiple image forming units GY, GM, GC, and GK include a yellow image forming unit GY, a magenta image forming unit GM, a cyan image forming unit GC, and a black image forming unit GK. Each image forming unit GY, GM, GC, and GK includes a photosensitive drum 331, a charged charger 332, an exposure unit 333, a developer 334, and a transfer roller 335. Each image forming unit GY, GM, GC, and GK transfers the toner image formed on the surface of the photosensitive drum 331 onto the intermediate transfer belt 31.

[0033] The secondary transfer section 22 includes a transfer roller 221. The transfer roller 221 contacts the outer surface of the intermediate transfer belt 31. A pulley 321 supporting the intermediate transfer belt 31 is included in the components of the secondary transfer section 22. The sheet S and the intermediate transfer belt 31 are sandwiched together between the transfer roller 221 and the pulley 321. Thus, the toner image on the intermediate transfer belt 31 is transferred onto the sheet S.

[0034] The fixing device 30 heats and pressurizes the toner image transferred onto the sheet S, fixing the toner image onto the sheet S. Details about the fixing device 30 will be described later.

[0035] The conveyor path 24 extends from the sheet supply section 13 through the secondary transfer section 22 and the fixing device 3 to the paper discharge section 15. The sheet S is conveyed in the conveyor path 24, moving from the sheet supply section 13 through the secondary transfer section 22 and the fixing device 30 to the paper discharge section 15. The paper discharge section 15 discharges the sheet S with the image formed by the printer section 14.

[0036] The control panel 16 includes a panel 161 and a display 162. The panel 161 receives input of various operating instructions. The display 162 is an image display device such as a liquid crystal display (LCD) or an organic EL (Electro-luminescence) display. The display 162 displays various information related to the image forming apparatus 1. For example, the display 162 displays the operating mode of the image forming apparatus 1 selected by the user. In this embodiment, the control panel 16 is equivalent to an "input unit".

[0037] The image forming apparatus 1 specifies its operating mode by performing an operation input, such as pressing an input button on the panel 161. Alternatively, the user can specify the operating mode of the image forming apparatus 1 by performing an operation input, such as clicking an icon displayed on a touch panel that integrates the display 162 and the panel 161. The control unit 17 controls each part of the image forming apparatus 1. Details of the control unit 17 will be described later.

[0038] Figure 2This diagram illustrates a specific example of the hardware configuration of the image forming apparatus 1. The image forming apparatus 1 includes a CPU (Central Processing Unit) 91, a memory 92, and an auxiliary storage device 93 connected via a bus, and executes a program. By executing the program, the image forming apparatus 1 functions as a device including a scanner unit 12, a sheet feed unit 13, a printer unit 14, a paper output unit 15, a control panel 16, and a communication unit 90. Furthermore, all or part of the functions of the image forming apparatus 1 can be implemented using hardware such as an ASIC (Application Specific Integrated Circuit), a PLD (Programmable Logic Device), or a FPGA (Field Programmable Gate Array). The program can also be recorded on a computer-readable recording medium. Examples of computer-readable recording media include removable media such as floppy disks, optical disks, ROMs, and CD-ROMs, and storage devices such as hard disks built into a computer system. The program can also be transmitted via an electrical communication line.

[0039] CPU 91 functions as control unit 17 by executing programs stored in memory 92 and auxiliary storage device 93. Control unit 17 controls the operation of each functional unit of image forming apparatus 1. Control unit 17 includes image processing unit 94. Image processing unit 94 is connected to CPU 91. Auxiliary storage device 93 is configured using a storage device such as a magnetic hard disk device or semiconductor storage device. Auxiliary storage device 93 stores various information related to image forming apparatus 1. Communication unit 90 is configured to include a communication interface for connecting this apparatus to an external device. Communication unit 90 communicates with external devices via the communication interface.

[0040] The configuration of the fixing device 30 in the following embodiment will be described in detail.

[0041] Figure 3 This is a cross-sectional view of the fixing device 30 viewed from the long side. The fixing device 30 has a fixing belt unit 40 and a pressure roller 41.

[0042] like Figure 3 As shown, a gap N is formed between the fixing belt unit 40 and the pressure roller 41. The fixing belt unit 40 heats the toner image T of the sheet S that enters the gap N. The fixing belt unit 40 includes a fixing belt 35, a heater unit 43, a first temperature detection unit 62, a thermostat unit 68, a second temperature detection unit 64, a heat-conducting unit 47, a support unit 48, and a support bar 49.

[0043] The XYZ coordinate system is sometimes used in the following description of the configuration of the fixing device 30. In the embodiment, the X, Y, and Z directions are defined as follows: The X direction corresponds to the direction along the short side of the heater unit 43. The Y direction corresponds to the direction along the long side (width direction) of the fixing belt unit 40 and the pressure roller 41. In this embodiment, the Y direction is orthogonal to the conveying direction W of the sheet S. The Z direction corresponds to the direction orthogonal to both the X and Y directions. Hereinafter, in the X direction, one side is referred to as the +X side and the other side as the -X side. In the Y direction, one side is referred to as the +Y side and the other side as the -Y side. In the Z direction, one side is referred to as the +Z side and the other side as the -Z side.

[0044] The fixing belt 35 has an annular circumferential surface. The fixing belt 35 is formed from a thin-film-like cylindrical body. From its inner circumferential side, the fixing belt 35 sequentially comprises a base layer, an elastic layer, and a release layer. The base layer is formed into a cylindrical shape. The elastic layer is laminated onto the outer circumferential surface of the base layer. The elastic layer is formed from an elastic material such as rubber. The release layer is laminated onto the outer circumferential surface of the elastic layer. The release layer is formed from a material such as PFA resin. In this embodiment, the fixing belt 35 is equivalent to a "thin-film-like cylindrical body".

[0045] The heater unit 43 is disposed inside the fixing belt 35. The heater unit 43 heats the fixing belt 35. The fixing belt 35 is heated by the heater unit 43, thereby fixing the toner image T onto the sheet S.

[0046] like Figure 3 As shown, the heater unit 43 is disposed inside the fixing belt 35. A lubricant (not shown) is coated on the inner circumferential surface of the fixing belt 35. The heater unit 43 contacts the inner circumferential surface of the fixing belt 35 through the lubricant. When the heater unit 43 heats up, the viscosity of the lubricant decreases, ensuring the sliding properties of the heater unit 43 and the fixing belt 35. The fixing belt 35 is a strip-shaped film that contacts the heater unit 43 on one surface while sliding on the surface of the heater unit 43.

[0047] The heat-conducting component 47 is formed of a metal material with high thermal conductivity, such as copper. The shape of the heat-conducting component 47 is the same as that of the heater unit 43. The heat-conducting component 47 is disposed in contact with the -Z side surface of the heater unit 43. The heat-conducting component 47 makes the temperature distribution of the heater unit 43 more uniform.

[0048] The support member 48 is formed of a resin material such as a liquid crystal polymer. The support member 48 is arranged to cover both sides of the heater unit 43 in the -Z and X directions. The support member 48 supports the heater unit 43 via the heat-conducting member 47. The two ends of the support member 48 in the X direction are rounded. The support member 48 supports the inner circumferential surface of the fixing belt 35 at both ends of the heater unit 43 in the X direction.

[0049] The support bar 49 is formed of a material such as steel plate. The cross-section of the support bar 49 along the XZ plane is U-shaped. The support bar 49 is installed on the -Z side of the support member 48 such that the opening of the U-shape is blocked by the support member 48. The support bar 49 extends along the Y direction. Both ends of the support bar 49 in the Y direction are fixed to the housing of the image forming apparatus 1. Thus, the fixing belt unit 40 is supported on the image forming apparatus 1. The support bar 49 improves the bending rigidity of the fixing belt unit 40. Near both ends of the support bar 49 in the Y direction, flanges 29 are installed to limit the movement of the fixing belt 35 in the Y direction.

[0050] The pressure roller 41 applies pressure to the toner image on the sheet S entering the roll gap N. The pressure roller 41 rotates to transport the sheet S. The pressure roller 41 has a metal core 141, an elastic layer 142, and a release layer 143. The pressure roller 41 is capable of pressing the surface onto the fixing belt 35 and rotating.

[0051] The metal core 141 is formed into a cylindrical shape from a metal material such as stainless steel. Both axial ends of the metal core 141 are rotatably supported on the housing 11. The metal core 141 rotates under the drive of a motor (not shown). The metal core 141 abuts against a cam component (not shown). The cam component rotates to move the metal core 141 closer to or further away from the fixing belt unit 40.

[0052] The elastic layer 142 is formed of an elastic material such as silicone rubber. The elastic layer 142 is formed on the outer peripheral surface of the metal core 141 with a certain thickness. The release layer 143 is formed of a resin material such as PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer). The release layer is formed on the outer peripheral surface of the elastic layer 142. The hardness of the outer peripheral surface of the pressure roller 41 is preferably measured to be 40° to 70° using an ASKER-C hardness tester under a load of 9.8N. This ensures the area of ​​the roll gap N and the durability of the pressure roller 41.

[0053] The pressure roller 41 can move closer to or further away from the fixing belt unit 40 by rotating the cam member. When the pressure roller 41 is brought closer to the fixing belt unit 40 and pressed by the pressure spring, a roller gap N is formed. On the other hand, when a sheet S jams in the fixing device 30, the sheet S can be removed by moving the pressure roller 41 away from the fixing belt unit 40. In addition, when the fixing belt 35 stops rotating, such as during sleep mode, plastic deformation of the fixing belt 35 can be prevented by moving the pressure roller 41 away from the fixing belt unit 40.

[0054] The pressure roller 41 rotates under the drive of a motor. When the pressure roller 41 rotates with the roller gap N formed, the fixing belt 35 of the fixing belt unit 40 rotates voluntarily. By rotating the pressure roller 41 with the sheet S positioned in the roller gap N, the sheet S is conveyed in the conveying direction W.

[0055] Figure 4 and Figure 5 This is a top view of heater unit 43. Figure 6 This is a cross-sectional view of heater unit 43. Furthermore, Figure 4 This is a top view of heater unit 43 viewed from the +Z side towards the -Z side. Figure 5 This is a bottom view of heater unit 43, viewed from the -Z side towards the +Z side. Additionally, Figure 6 It is a cross-sectional view of heater unit 43 on a plane parallel to the XZ plane.

[0056] like Figure 4 and Figure 5 As shown, the heater unit 43 includes a substrate 50, a heating element 70, and a wiring assembly 60. The substrate 50 is formed of a metallic material such as stainless steel or a ceramic material such as aluminum nitride. The substrate 50 is formed into an elongated rectangular plate along the Y-axis. The substrate 50 is disposed on the radially inner side (-Z side) of the fixing belt 35. The substrate 50 has its long side in the axial direction of the fixing belt 35.

[0057] like Figure 6 As shown, the substrate 50 has a first surface 501 and a second surface 502 facing opposite directions. The first surface 501 faces the +Z side, and the second surface 502 faces the -Z side. An insulating layer 51 made of glass or the like is formed on the first surface 501 and the second surface 502 of the substrate 50. In the embodiment, the first surface 501 side of the substrate 50 of the heater unit 43 abuts against the inner peripheral surface of the fixing belt 35.

[0058] The heating element 70 and the wiring assembly 60 are disposed on the substrate 50 with an insulating layer 51 between them. The heating element 70 and the wiring assembly 60 are covered by a protective layer 55 made of glass or the like. The protective layer 55 improves the sliding properties of the heater unit 43 and the fixing belt 35. Furthermore, Figure 4 and Figure 5 The illustration of protective layer 55 is omitted.

[0059] like Figure 4 and Figure 5 As shown, the heating element 70 has a first heating portion 71 disposed on a first surface 501 of a substrate 50 through an insulating layer 51, and a second heating portion 72 disposed on a second surface 502 of the substrate 50 through an insulating layer 51. The first heating portion 71 and the second heating portion 72 are formed of a TCR (temperature coefficient of resistance) material. For example, the first heating portion 71 and the second heating portion 72 are formed of a silver-palladium alloy or the like.

[0060] The first heating element 71 in this embodiment includes a central heating element 171. The central heating element 171 is located at the center of the first surface 501 of the substrate 50. In this embodiment, the central heating element 171 is disposed on the side of the heater unit 43 that contacts the first surface 501 of the fixing belt 35.

[0061] The central heating element 171 has a rectangular shape with a long side along the Y direction and a short side along the X direction. The central heating element 171 is arranged along the long side of the substrate 50. In this embodiment, the central heating element 171 is equivalent to a "first heating element".

[0062] The second heating element 72 in this embodiment includes a first end heating element 172 and a second end heating element 173. The first end heating element 172 and the second end heating element 173 are disposed on the second surface 502 of the substrate 50. In this embodiment, the first end heating element 172 and the second end heating element 173 are disposed on the second surface 502 side of the heater unit 43 opposite to the first surface 501 that contacts the fixing belt 35.

[0063] The first end heating element 172 and the second end heating element 173 are rectangular in shape, having a long side along the Y direction and a short side along the X direction. The Y-direction dimension of the first end heating element 172 and the second end heating element 173 is smaller than the Y-direction dimension of the central heating element 171. The X-direction dimension of the first end heating element 172 and the second end heating element 173 is equal to the X-direction dimension of the central heating element 171. In this embodiment, the first end heating element 172 and the second end heating element 173 are equivalent to "a plurality of second heating elements".

[0064] When the heater unit 43 is viewed from above along the thickness direction of the substrate 50, that is, when the heater unit 43 is viewed from above along the Z direction, the first heating element 71 and the second heating element 72 are arranged along the long side direction of the substrate 50. Hereinafter, the heater unit 43 viewed from above along the Z direction will be referred to simply as "viewed from above".

[0065] In a top view, the first end heating element 172 and the second end heating element 173 are arranged along the long side direction (Y direction) of the substrate 50. The first end heating element 172 is disposed at the -Y side end of the second surface 502 of the substrate 50. The second end heating element 173 is disposed at the +Y side end of the second surface 502 of the substrate 50. The first end heating element 172 is disposed on the -Y side of the central heating element 171, and the second end heating element 173 is disposed on the +Y side of the central heating element 171. The first end heating element 172 and the second end heating element 173 are located outside the long side direction (+Y side or -Y side) of the substrate 50 relative to the central heating element 171.

[0066] When viewed from above, the first heating element 71 and the second heating element 72 are arranged such that a portion of each overlaps.

[0067] A portion of the first end heating element 172 and the central heating element 171 overlap each other along the long side of the substrate 50. A portion of the second end heating element 173 and the central heating element 171 overlap each other along the long side of the substrate 50. The overlap amount OB between the first end heating element 172 and the central heating element 171 is equal to the overlap amount OB between the second end heating element 173 and the central heating element 171.

[0068] In the heater unit 43 of this embodiment, by arranging the first heating element 71 and the second heating element 72 in an overlapping state, it is possible to prevent the temperature of the boundary portions of each heating element 71, 72 from dropping. Furthermore, the overlap amount OB is preferably 10 mm or less, and more preferably 5 mm or less. By setting the overlap amount OB within the above range, it is possible to suppress undesirable situations where the temperature of the boundary portions of each heating element becomes too high due to an excessively large overlap amount OB.

[0069] In the heater unit 43 of this embodiment, by dispersing the first end heating element 172 and the second end heating element 173 on both ends of the substrate 50, it is possible to achieve the structure described above in which the first heating element 71 and the second heating element 72 are arranged to overlap when viewed from above.

[0070] The wiring assembly 60 is formed of a metallic material such as silver. The wiring assembly 60 includes a first electrode portion 81, a second electrode portion 82, a first wiring portion 83, and a second wiring portion 84.

[0071] The first electrode portion 81 and the first wiring portion 83 are disposed on the first surface 501 of the substrate 50 through the insulating layer 51. The first electrode portion 81 supplies power to the first heating portion 71 via the first wiring portion 83. The first electrode portion 81 is disposed at the end of the substrate 50 in the long side direction.

[0072] The first electrode section 81 includes a positive electrode 811 and a common electrode 812. The positive electrode 811 is disposed at the -Y side and +X side ends of the substrate 50. The common electrode 812 is disposed at the +Y side and -X side ends of the substrate 50.

[0073] The first wiring section 83 includes a positive wiring 831 and a common wiring 832. The positive wiring 831 is connected to the +X side of the central heating element 171 and extends toward the -Y side. The positive wiring 831 connects the central heating element 171 and the positive electrode 811. The common wiring 832 is connected to the -X side of the central heating element 171 and extends toward the +Y side. The common wiring 832 connects the central heating element 171 and the common electrode 812.

[0074] The second electrode portion 82 and the second wiring portion 84 are disposed on the second surface 502 of the substrate 50 through the insulating layer 51. The second electrode portion 82 supplies power to the second heating portion 72 via the second wiring portion 84. The second electrode portion 82 is disposed at the end in the long side direction of the substrate 50.

[0075] The second electrode section 82 includes a positive electrode 821 and a common electrode 822. The positive electrode 821 is disposed at the ends of the substrate 50 on the -Y and -X sides. The common electrode 822 is disposed at the ends of the substrate 50 on the +Y and +X sides.

[0076] The second wiring section 84 includes a positive wiring 841 and a common wiring 842. The positive wiring 841 is disposed on the -X side of the first end heating element 172 and the second end heating element 173. The positive wiring 841 is connected to the -X side of the first end heating element 172 and the second end heating element 173 and extends towards the -Y side. The positive wiring 841 connects the first end heating element 172 and the second end heating element 173 to the positive electrode 821. The common wiring 842 is connected to the +X side of the first end heating element 172 and the second end heating element 173 and extends towards the +Y side. The common wiring 842 connects the first end heating element 172 and the second end heating element 173 to the common electrode 822.

[0077] In the heater unit 43 of this embodiment, the first heating portion 71 and the second heating portion 72 constituting the heating element 70 are distributed on both sides of the substrate 50. Therefore, on the first surface 501 of the substrate 50, only the first electrode portion 81 and the first wiring portion 83 connected to the first heating portion 71 are formed. Furthermore, on the second surface 502 of the substrate 50, only the second electrode portion 82 and the second wiring portion 84 connected to the second heating portion 72 are formed.

[0078] When viewed from above, the first electrode portion 81 and the second electrode portion 82 are positioned in a non-overlapping manner. In this embodiment, the positive electrode 811, the common electrode 812, the positive electrode 821, and the common electrode 822 are respectively disposed at the corners of the substrate 50.

[0079] In this embodiment, the heating element 70 heats up by being energized. The resistance value of the central heating element 171 is less than the resistance values ​​of the first end heating element 172 and the second end heating element 173. In this embodiment, the sheet S with a small width in the Y direction passes through the central portion of the fixing device 30 in the Y direction. In this case, the control unit 17 only heats the central heating element 171. On the other hand, in the case of a sheet S with a large width in the Y direction, the control unit 17 heats the entire heating element 70, namely the central heating element 171, the first end heating element 172, and the second end heating element 173.

[0080] In this embodiment, the central heating element 171, the first end heating element 172, and the second end heating element 173 can be controlled to generate heat independently of each other. Furthermore, the first end heating element 172 and the second end heating element 173 are controlled to generate heat in the same way.

[0081] Figure 7 This is a top view (viewed from the -Z side) of the first temperature sensing component 62 and the thermostat section 68. Figure 7 The description of the support member 48 is omitted here. The following description of the configuration of the first temperature sensing member 62 and the thermostat unit 68 explains the configuration of each temperature sensing element.

[0082] like Figure 7 As shown, a first temperature sensing element 62 is disposed on the -Z side of the heater unit 43, separated by a heat-conducting element 47. For example, the first temperature sensing element 62 is a thermistor. The first temperature sensing element 62 is mounted and supported on the surface of the support member 48 on the -Z side. The temperature-sensing element of the first temperature sensing element 62 contacts the heat-conducting element 47 through a hole penetrating the support member 48 in the Z direction. The first temperature sensing element 62 measures the temperature of the heater unit 43 via the heat-conducting element 47.

[0083] The first temperature sensing element 62 includes a central heater thermometer 621 and an end heater thermometer 622 arranged along the Y direction. The central heater thermometer 621 and the end heater thermometer 622 are disposed within the Y direction range of the heating element 70. The central heater thermometer 621 and the end heater thermometer 622 are disposed at the center of the heating element 70 in the X direction. Viewed from the Z direction, the central heater thermometer 621 and the end heater thermometer 622 overlap at least partially with the heating element 70.

[0084] In the first temperature sensing unit 62, the central heater thermometer 621 measures the temperature of the central heating element 171. The central heater thermometer 621 is disposed within the area of ​​the central heating element 171. Viewed from the Z direction, the central heater thermometer 621 overlaps with the central heating element 171.

[0085] In the first temperature detection unit 62, the end heater thermometer 622 measures the temperature of the first end heating element 172. Since the heating of the first end heating element 172 and the second end heating element 173 is controlled by the control unit 17 in the same way, the temperature of the first end heating element 172 is the same as the temperature of the second end heating element 173. The end heater thermometer 622 is disposed within the range of the first end heating element 172. Viewed in the Z direction, the end heater thermometer 622 overlaps with the first end heating element 172. Alternatively, an end heater thermometer 622 measuring the temperature of the second end heating element 173 may also be provided separately.

[0086] When the temperature of the heater unit 43, detected by the heat-conducting member 47, exceeds a predetermined temperature, the thermostat unit 68 cuts off the power supply to the heating member 70. The thermostat unit 68 includes a central thermostat 681 and an end thermostat 682. The thermostat unit 68 is also configured in the same way as the first temperature detection member 62 described above.

[0087] The central thermostat 681 cuts off the power supply to the heating element 70 when the temperature of the central heating element 171 exceeds a specified temperature. The central thermostat 681 is located within the area of ​​the central heating element 171. Viewed from the Z direction, the central thermostat 681 overlaps with the central heating element 171.

[0088] When the temperature of the second end heating element 173 exceeds a predetermined temperature, the end thermostat 682 cuts off the power supply to the heating element 70. Since the first end heating element 172 and the second end heating element 173 control heating in the same way, the temperature of the first end heating element 172 is the same as the temperature of the second end heating element 173. The end thermostat 682 is disposed within the range of the second end heating element 173. Viewed from the Z direction, the end thermostat 682 overlaps with the second end heating element 173.

[0089] In the heater unit 43 of this embodiment, the temperature of the central heating element 171 is controlled by arranging a central heater thermometer 621 and a central thermostat 681 within the range of the central heating element 171. Furthermore, in the heater unit 43 of this embodiment, the temperature of the first end heating element 172 and the second end heating element 173 is controlled by arranging an end heater thermometer 622 and an end thermostat 682 within the range of the first end heating element 172 and the second end heating element 173.

[0090] like Figure 3 As shown, the second temperature sensing component 64 is disposed on the +X side of the inner side of the fixing belt 35. The second temperature sensing component 64 is in contact with the inner circumferential surface of the fixing belt 35 and measures the temperature of the fixing belt 35.

[0091] Figure 8 This is the circuit diagram of the fixing device 30. Figure 8 The middle and upper sections show Figure 4 A top view, shown in the lower section. Figure 7 A top view. Additionally, in Figure 8 In the top view above the lower section, a second temperature sensing component 64 is shown together with a cross-section of the fixing belt 35. The second temperature sensing component 64 includes a central thermometer 641 and an end thermometer 642.

[0092] The central part thermometer 641 is in contact with the central part of the fixing belt 35 in the Y direction. The central part thermometer 641 is in contact with the fixing belt 35 within the Y direction range of the central part heating element 171. The central part thermometer 641 measures the temperature of the central part of the fixing belt 35 in the Y direction.

[0093] The end-mounted thermometer 642 contacts the -Y side end of the fixing belt 35. The end-mounted thermometer 642 contacts the fixing belt 35 within the Y direction range of the second end-mounted heating element 173. The end-mounted thermometer 642 measures the temperature of the -Y side end of the fixing belt 35. As described above, the first end-mounted heating element 172 and the second end-mounted heating element 173 are controlled to generate heat in the same way. In this embodiment, the temperature of the -Y side end of the fixing belt 35 is the same as the temperature of the +Y side end.

[0094] Power supply 95 is connected to the positive electrode 811 of the first electrode section 81 via a central three-terminal bidirectional thyristor switch 96. Power supply 95 is connected to the positive electrode 821 of the second electrode section 82 via an end three-terminal bidirectional thyristor switch 97. Control unit 17 independently controls the on / off state of the central three-terminal bidirectional thyristor switch 96 and the end three-terminal bidirectional thyristor switch 97.

[0095] When the control unit 17 turns on the central three-terminal bidirectional thyristor switch 96, power is supplied from the power supply 95 to the central heating element 171, causing the central heating element 171 to heat up. When the control unit 17 turns on the end three-terminal bidirectional thyristor switches 97, power is supplied from the power supply 95 to the first end heating element 172 and the second end heating element 173, causing the first end heating element 172 and the second end heating element 173 to heat up. Therefore, the heating of the central heating element 171, the first end heating element 172, and the second end heating element 173 are controlled independently. The central heating element 171, the first end heating element 172, and the second end heating element 173 are connected in parallel with the power supply 95.

[0096] The power supply 95 is connected to the common electrode 812 of the first electrode section 81 and the common electrode 822 of the second electrode section 82 via the central thermostat 681 and the end thermostat 682. The central thermostat 681 and the end thermostat 682 are connected in series. When the temperature of the central heating element 171 rises abnormally, the temperature detected by the central thermostat 681 exceeds the specified temperature. At this time, the central thermostat 681 cuts off the power supply from the power supply 95 to the entire heating element 70.

[0097] When the temperature of the second end heating element 173 rises abnormally, the temperature detected by the end thermostat 682 exceeds the specified temperature. At this time, the end thermostat 682 cuts off the power supply from the power source 95 to the entire heating element 70. As described above, the first end heating element 172 and the second end heating element 173 are controlled to generate heat in the same way. Therefore, when the temperature of the first end heating element 172 rises abnormally, the temperature of the second end heating element 173 also rises. The end thermostat 682 also cuts off the power supply from the power source 95 to the entire heating element 70 when the temperature of the first end heating element 172 rises abnormally.

[0098] The control unit 17 measures the temperature of the central heating element 171 using the central heater thermometer 621. The control unit 17 also measures the temperature of the first end heating element 172 using the end heater thermometer 622. The temperature of the first end heating element 172 is the same as the temperature of the second end heating element 173. The control unit 17 measures the temperature of the heating element 70 using the first temperature detection unit 62 when the fixing device 30 is started (during preheating) and when it resumes from a temporary pause state (dormant state).

[0099] When the fixing unit 30 is started or resumed from a temporary pause, if the temperature of at least one of the central heating element 171 or the second end heating element 173 is lower than a predetermined temperature, the control unit 17 causes the heating element 70 to heat up for a short period of time. Then, the control unit 17 causes the pressure roller 41 to start rotating. The heating of the heating element 70 reduces the viscosity of the lubricant applied to the inner circumferential surface of the fixing belt 35. This ensures the smooth sliding of the fixing belt unit 40 and the fixing belt 35 when the pressure roller 41 starts rotating.

[0100] The control unit 17 measures the temperature of the central portion of the fixing belt 35 in the Y direction using a central portion thermometer 641. The control unit 17 also measures the temperature of the -Y side end of the fixing belt 35 using an end thermometer 642. The temperature of the -Y side end of the fixing belt 35 is the same as the temperature of the +Y side end of the fixing belt 35. The control unit 17 measures the temperature of the central portion and the end of the fixing belt 35 in the Y direction when the fixing device 30 is operating.

[0101] As described above, the control unit 17 performs phase control or wavenumber control on the power supplied to the heating element 70 via the central three-terminal bidirectional thyristor switch 96 and the end three-terminal bidirectional thyristor switches 97. The control unit 17 controls the power supply to the central heating element 171 based on the temperature measurement results of the central part of the fixing belt 35 in the Y direction. The control unit 17 controls the power supply to the first end heating element 172 and the second end heating element 173 based on the temperature measurement results of the ends of the fixing belt 35 in the Y direction.

[0102] As described above, the fixing apparatus 30 of this embodiment includes a heater unit 43 configured as described above. The heater unit 43 includes: a substrate 50; a first heating element 71 disposed on the first surface 501 side of the substrate 50; a first wiring element 83 disposed on the first surface 501 side of the substrate 50 and connected to the first heating element 71; a first electrode element 81 disposed on the first surface 501 side of the substrate 50 and supplying power to the first heating element 71 via the first wiring element 83; a second heating element 72 disposed on the second surface 502 side of the substrate 50 opposite to the first surface 501; a second wiring element 84 disposed on the second surface 502 side of the substrate 50 and connected to the second heating element 72; and a second electrode element 82 disposed on the second surface 502 side of the substrate 50 and supplying power to the second heating element 72 via the second wiring element 84.

[0103] In the heater unit 43 of this embodiment, the first wiring portion 83 connecting the first heating portion 71 and the first electrode portion 81 and the second wiring portion 84 connecting the second heating portion 72 and the second electrode portion 82 are distributed on both sides of the substrate 50.

[0104] When the first wiring portion 83 and the second wiring portion 84 are distributed on both sides of the substrate 50 in this way, the first wiring portion 83 and the second wiring portion 84 are no longer formed on the same side of the substrate 50. Therefore, the first wiring portion 83 and the second wiring portion 84 are not arranged along the short side direction (X direction) of the substrate 50, thus enabling the size of the substrate 50 in the short side direction to be miniaturized.

[0105] According to the heater unit 43 of this embodiment, even when a structure consisting of multiple heating elements arranged as the heating element 70 is adopted, the size of the substrate 50 in the X direction can be reduced. According to the fixing apparatus 30 of this embodiment, since the heater unit 43 is provided, miniaturization and cost reduction of the fixing apparatus itself can be achieved. Furthermore, according to the image forming apparatus 1 of this embodiment, since the small fixing apparatus 30 is provided, the image forming apparatus itself can be miniaturized.

[0106] (Second Implementation)

[0107] Next, the image forming apparatus of the second embodiment will be described. The image forming apparatus of this embodiment differs from the image forming apparatus of the first embodiment in the configuration of the heater unit in the fixing device; otherwise, their configurations are the same. Hereinafter, the configuration of the fixing device will be described primarily, while other descriptions will be omitted. The same reference numerals will be used for components shared with the first embodiment.

[0108] Figure 9 and Figure 10 This is a top view of the heater unit 243 according to the second embodiment. Furthermore, Figure 9This is a bottom view of heater unit 243 viewed from the +Z side towards the -Z side. Figure 10 This is a top view of heater unit 243 viewed from the -Z side toward the +Z side.

[0109] like Figure 9 and Figure 10 As shown, the heater unit 243 includes a substrate 50, a heating element 170, and a wiring assembly 60. The heating element 170 has a first heating portion 71 disposed on a first surface 501 of the substrate 50 through an insulating layer 51, and a second heating portion 72 disposed on a second surface 502 of the substrate 50 through an insulating layer 51.

[0110] When viewed from above, the heater unit 243 of this embodiment is arranged such that the first heating element 71 and the second heating element 72 are partially overlapping. The positions of the first heating element 71 and the second heating element 72 in the short side direction (X direction) of the substrate 50 are different from each other. In the short side direction of the substrate 50, the first heating element 71 is located upstream of the sheet S in the conveying direction W, which is closer to the second heating element 72.

[0111] Since the sheet S elongates upon heating, if the first heating element 71 and the second heating element 72 are heated simultaneously, the heating element 70 heats the entire Y direction of the sheet S at the same time. At this time, the central portion and the ends of the sheet S extend in different directions simultaneously, which may cause damage such as wrinkles or curling on the sheet S.

[0112] In contrast, according to the heater unit 243 of this embodiment, when heating the sheet S, the heating time of the first heating element 71 located upstream of the conveying direction W of the sheet S can be different from the heating time of the second heating element 72 located downstream of the conveying direction W. The first heating element 71 heats the central portion of the conveyed sheet S, while the second heating element 72 heats both ends of the sheet S. Therefore, when the sheet S is heated by the heater unit 243 of this embodiment, the two ends of the sheet elongate after the central portion of the sheet elongates. Thus, compared to when the entire sheet elongates simultaneously, damage such as wrinkles and curling on the sheet S can be reduced.

[0113] (Third Implementation)

[0114] Next, the image forming apparatus of the third embodiment will be described. The image forming apparatus of this embodiment differs from the image forming apparatus of the first embodiment in the configuration of the heater unit in the fixing device; otherwise, their configurations are the same. Hereinafter, the configuration of the fixing device will be mainly described, and other descriptions will be omitted. The same reference numerals will be used for components shared with the first embodiment.

[0115] Figure 11 and Figure 12 This is a top view of the heater unit 343 according to the third embodiment. Furthermore, Figure 11 This is a bottom view of heater unit 343 viewed from the +Z side towards the -Z side. Figure 12 This is a top view of heater unit 343 viewed from the -Z side toward the +Z side.

[0116] like Figure 11 and Figure 12 As shown, the heater unit 343 includes a substrate 50, a heating element 270, and a wiring assembly 60. The heating element 270 has a first heating portion 371 disposed on a first surface 501 of the substrate 50 through an insulating layer 51, and a second heating portion 372 disposed on a second surface 502 of the substrate 50 through an insulating layer 51. The first heating portion 371 includes a central heating element 171. The second heating portion 372 includes a first end heating element 172 and a second end heating element 173.

[0117] When viewed from above, the heater unit 343 of this embodiment is arranged such that the first heating element 371 and the second heating element 372 are partially overlapped.

[0118] The width Wa of the central heating element 171 of the first heating section 371 in the short side direction (the conveying direction W of the sheet S) of the substrate 50 is narrower than the width Wb of the first end heating element 172 and the second end heating element 173 of the second heating section 372 in the short side direction of the substrate 50. That is, the width Wa of the central heating element 171 that heats the central part of the sheet S is narrower than the width Wb of the first end heating element 172 and the second end heating element 173 that heat the two ends of the sheet S.

[0119] Here, when heating sheet S, in the width direction of sheet S, which is orthogonal to the conveying direction W, heat is more easily dissipated from both ends of the sheet compared to the center. Therefore, when the heat generation in the center and both ends of sheet S in the width direction is the same, the heating at both ends of sheet S becomes insufficient, which may result in poor fixing of the toner.

[0120] In contrast, according to the heater unit 343 of this embodiment, by relatively increasing the width of the second heating section 372, which heats both ends of the sheet S, in the conveying direction W, the heat generation at both ends of the sheet S, which dissipates heat more easily than the central portion, can be increased. Therefore, poor fixing of the toner can be prevented by sufficiently heating the entire width direction of the sheet S.

[0121] Furthermore, when viewed from above, the distance DA from the short side 503 of the substrate 50 (upstream of the conveying direction W of the sheet S) to the end of the first heating part 371 is equal to the distance DB from the short side 503 to the end of the second heating part 372.

[0122] In this embodiment, when viewed from above, the position of the first heating element 371 starting from the short side 503 is the same as the position of the second heating element 372 starting from the short side 503.

[0123] According to the heater unit 343 of this embodiment, by aligning the positions of the first heating element 371 and the second heating element 372 from the short side 503, and by making the widths Wa and Wb of the first heating element 371 and the second heating element 372 different as described above, it is possible to suppress excessive enlargement of the substrate 50 in the short side direction.

[0124] (Fourth Implementation)

[0125] Next, the image forming apparatus of the fourth embodiment will be described. The image forming apparatus of this embodiment differs from the image forming apparatus of the first embodiment in the configuration of the heater unit in the fixing device; otherwise, their configurations are the same. Hereinafter, the configuration of the fixing device will be mainly described, and other descriptions will be omitted. The same reference numerals will be used for components shared with the first embodiment.

[0126] In the first embodiment, the first heating part 71 provided on the first surface 501 side of the substrate 50 is given as an example, which includes only one heating element (central heating element 171). However, in this embodiment, the first heating part includes multiple heating elements.

[0127] Figure 13 and Figure 14 This is a top view of the heater unit 443 according to this embodiment. Furthermore, Figure 13 This is a top view of heater unit 443 viewed from the +Z side towards the -Z side. Figure 14 This is a bottom view of heater unit 443 viewed from the -Z side towards the +Z side.

[0128] like Figure 13 and Figure 14 As shown, the heater unit 443 includes a substrate 50, a heating element 370, and a wiring assembly 160. The heating element 370 has a first heating portion 471 disposed on a first surface 501 of the substrate 50 through an insulating layer 51, and a second heating portion 72 disposed on a second surface 502 of the substrate 50 through an insulating layer 51.

[0129] The first heating element 471 in this embodiment includes a central heating element 171, a third end heating element 174, and a fourth end heating element 175. The third end heating element 174 and the fourth end heating element 175 are rectangular in shape, having a long side along the Y direction and a short side along the X direction. The shapes of the third end heating element 174 and the fourth end heating element 175 are the same as those of the first end heating element 172 and the second end heating element 173 in the second heating element 72.

[0130] Viewed from above, the central heating element 171, the third end heating element 174, and the fourth end heating element 175 are arranged along the long side of the substrate 50. The third end heating element 174 is located on the -Y side of the central heating element 171, and the fourth end heating element 175 is located on the +Y side of the central heating element 171. The first end heating element 172 is located between the central heating element 171 and the third end heating element 174 along the long side of the substrate 50. The second end heating element 173 is located between the central heating element 171 and the fourth end heating element 175 along the long side of the substrate.

[0131] The wiring assembly 160 includes a first electrode portion 181, a second electrode portion 82, a first wiring portion 183, and a second wiring portion 84. The first electrode portion 181 and the first wiring portion 183 are disposed on the first surface 501 of the substrate 50 through an insulating layer 51.

[0132] The first electrode section 181 includes a central positive electrode 911, a common electrode 912, a first end positive electrode 913, and a second end positive electrode 914.

[0133] A central positive electrode 911 is disposed at the -Y and +X sides of the substrate 50. A first end positive electrode 913 is disposed on the substrate 50 adjacent to the -X side of the central positive electrode 911. A common electrode 912 is disposed at the +Y and -X sides of the substrate 50. A second end positive electrode 914 is disposed on the substrate 50 adjacent to the +X side of the common electrode 912.

[0134] The first wiring section 183 includes a central main wiring 931, a common wiring 932, a first end main wiring 933, and a second end main wiring 934.

[0135] Central positive wiring 931 connects the central heating element 171 and the central positive electrode 911. Common wiring 932 connects the central heating element 171, the third end heating element 174, and the fourth end heating element 175 to the common electrode 912. First end positive wiring 933 connects the third end heating element 174 and the first end positive electrode 913. Second end positive wiring 934 connects the fourth end heating element 175 and the second end positive electrode 914.

[0136] When viewed from above, the heater unit 443 of this embodiment is arranged such that the first heating element 471 and the second heating element 72 are partially overlapped.

[0137] The first end heating element 172, the third end heating element 174, and the central heating element 171 partially overlap each other along the long side of the substrate 50. The second end heating element 173, the fourth end heating element 175, and the central heating element 171 partially overlap each other along the long side of the substrate 50. The overlap amount of each heating element is the same.

[0138] In the heater unit 443 of this embodiment, by arranging the first heating element 471 and the second heating element 72 in a state of overlapping each other, it is possible to prevent the temperature of the boundary portions of each heating element 471, 72 from dropping. Furthermore, the aforementioned overlap amount is preferably 10 mm or less, and more preferably 5 mm or less.

[0139] When viewed from above, the first electrode portion 181 and the second electrode portion 82 are positioned in a non-overlapping manner. In this embodiment, the central positive electrode 911, the common electrode 912, the positive electrode 821, and the common electrode 822 are respectively disposed at the corners of the substrate 50. When viewed from above, the first end positive electrode 913 is disposed between the central positive electrode 911 and the positive electrode 821. When viewed from above, the second end positive electrode 914 is disposed between the common wiring 932 and the common electrode 822.

[0140] In the heater unit 443 of this embodiment, the first wiring portion 183 connecting the first heating portion 471 and the first electrode portion 181 and the second wiring portion 84 connecting the second heating portion 72 and the second electrode portion 82 are distributed on both sides of the substrate 50.

[0141] When the first wiring portion 183 and the second wiring portion 84 are distributed on both sides of the substrate 50 in this way, the first wiring portion 183 and the second wiring portion 84 are no longer formed on the same side of the substrate 50. Therefore, the first wiring portion 183 and the second wiring portion 84 are not arranged along the short side direction (X direction) of the substrate 50, thus enabling the size of the substrate 50 in the short side direction to be miniaturized.

[0142] According to the heater unit 443 of this embodiment, even when the first heating portion 471 provided on the first surface 501 of the substrate 50 includes multiple heating elements, the size increase of the substrate 50 in the short side direction (X direction) can be suppressed in the same way as in the other embodiments described above. Therefore, the fixing device equipped with the heater unit 443, or the image forming apparatus equipped with the fixing device itself, can be miniaturized.

[0143] While several embodiments have been described, these embodiments are merely illustrative and not intended to limit the scope of the invention. These embodiments can be implemented in various other ways, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included within the scope and spirit of the invention, and likewise within the scope of the invention as described in the claims and its equivalents.

Claims

1. A heater unit, characterized in that, have: A substrate having a long side and a short side; A central heating element is disposed in the central part of the first surface side of the substrate; A first wiring portion is disposed on the first side of the substrate and connected to the central heating element; The first electrode portion is disposed on the first surface side of the substrate and supplies power to the central heating element via the first wiring portion; The first end heating element is disposed on the end of the substrate on the side opposite to the first surface of the substrate, opposite to the central heating element, in the long side direction of the substrate. The second end heating element is disposed on the second surface side of the substrate, opposite to the central heating element on the other side of the substrate along the long side direction. The second wiring portion is disposed on the second side of the substrate and is connected to the first end heating element and the second end heating element; as well as The second electrode portion is disposed on the second surface side of the substrate, and supplies power to the first end heating element and the second end heating element via the second wiring portion. The central heating element, the first end heating element, and the second end heating element are arranged along the long side of the substrate. When the heater unit is viewed from above along the thickness direction of the substrate, the central heating element, the first end heating element, and the second end heating element are positioned differently along the short side of the substrate.

2. The heater unit according to claim 1, characterized in that, The first electrode portion and the second electrode portion are disposed at the ends of the substrate along its long side; When the heater unit is viewed from above along the thickness direction of the substrate, the first electrode portion and the second electrode portion are arranged in a position that does not overlap.

3. The heater unit according to claim 1 or 2, characterized in that, When the heater unit is viewed from above along the thickness direction of the substrate, a portion of the central heating element and a portion of the first end heating element overlap along the long side of the substrate, and... The central heating element and the second end heating element each overlap a portion of the long side of the substrate.

4. A fixing device, characterized in that, The heater unit is provided with any one of claims 1 to 3; It has a thin-film-shaped cylindrical body for housing the heater unit; The first side of the heater unit abuts against the cylindrical body.

5. An image forming apparatus, characterized in that, It has the fixing device as described in claim 4.

Images