US20220121144A1 - Heating device with thermometers and thermostats alternately arranged on a heat conductor - Google Patents
Heating device with thermometers and thermostats alternately arranged on a heat conductor Download PDFInfo
- Publication number
- US20220121144A1 US20220121144A1 US17/562,867 US202117562867A US2022121144A1 US 20220121144 A1 US20220121144 A1 US 20220121144A1 US 202117562867 A US202117562867 A US 202117562867A US 2022121144 A1 US2022121144 A1 US 2022121144A1
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- United States
- Prior art keywords
- heating element
- temperature
- fixing device
- heating elements
- sheet
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G15/00—Apparatus for electrographic processes using a charge pattern
- G03G15/20—Apparatus for electrographic processes using a charge pattern for fixing, e.g. by using heat
- G03G15/2003—Apparatus for electrographic processes using a charge pattern for fixing, e.g. by using heat using heat
- G03G15/2014—Apparatus for electrographic processes using a charge pattern for fixing, e.g. by using heat using heat using contact heat
- G03G15/2039—Apparatus for electrographic processes using a charge pattern for fixing, e.g. by using heat using heat using contact heat with means for controlling the fixing temperature
- G03G15/2042—Apparatus for electrographic processes using a charge pattern for fixing, e.g. by using heat using heat using contact heat with means for controlling the fixing temperature specially for the axial heat partition
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G15/00—Apparatus for electrographic processes using a charge pattern
- G03G15/20—Apparatus for electrographic processes using a charge pattern for fixing, e.g. by using heat
- G03G15/2003—Apparatus for electrographic processes using a charge pattern for fixing, e.g. by using heat using heat
- G03G15/2014—Apparatus for electrographic processes using a charge pattern for fixing, e.g. by using heat using heat using contact heat
- G03G15/2039—Apparatus for electrographic processes using a charge pattern for fixing, e.g. by using heat using heat using contact heat with means for controlling the fixing temperature
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G15/00—Apparatus for electrographic processes using a charge pattern
- G03G15/20—Apparatus for electrographic processes using a charge pattern for fixing, e.g. by using heat
- G03G15/2003—Apparatus for electrographic processes using a charge pattern for fixing, e.g. by using heat using heat
- G03G15/2014—Apparatus for electrographic processes using a charge pattern for fixing, e.g. by using heat using heat using contact heat
- G03G15/2053—Structural details of heat elements, e.g. structure of roller or belt, eddy current, induction heating
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G15/00—Apparatus for electrographic processes using a charge pattern
- G03G15/55—Self-diagnostics; Malfunction or lifetime display
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G15/00—Apparatus for electrographic processes using a charge pattern
- G03G15/80—Details relating to power supplies, circuits boards, electrical connections
Definitions
- An embodiment of the present invention relates to a heating device and an image processing apparatus.
- An image forming apparatus for forming an image on a sheet includes a heating apparatus for fixing a toner (i.e., recording agent) to the sheet. Heating temperature is required to be appropriately controlled in the heating apparatus.
- a toner i.e., recording agent
- FIG. 1 is a schematic configuration diagram of an image forming apparatus according to one embodiment.
- FIG. 2 is a hardware configuration diagram of the image forming apparatus.
- FIG. 3 is a front sectional view of a fixing unit according to one embodiment.
- FIG. 4 is a front sectional view of a heater unit of the fixing unit.
- FIG. 5 is a bottom view of the heater unit.
- FIG. 6 is a plan view of a heater thermometer and a thermostat.
- FIG. 7 is an electric circuit diagram of the fixing unit.
- a fixing device which heats an image formed on a sheet to fix the image thereon, includes a cylindrical film supported in a rotatable manner and having an outer circumferential surface that comes into contact with the sheet, and a heater unit provided in an inner space of the cylindrical film to heat an inner circumferential surface thereof.
- the heater unit includes a plurality of first heating elements disposed along a longitudinal direction of the cylindrical film, and a first temperature sensor configured to measure a temperature of one of the plurality of first heating elements.
- the plurality of first heating elements and the first temperature sensor are connected in series by a first wiring.
- FIG. 1 is a schematic configuration diagram of an image forming apparatus according to one embodiment of the present invention.
- the image forming apparatus 1 performs processing for forming an image on a sheet of paper S.
- the image forming apparatus 1 includes a housing 10 , a scanner unit 2 , an image forming unit 3 , a sheet supply unit 4 , a forcing unit 5 , a paper discharge tray 7 , a reversing unit 9 , a control panel 8 , and a controller 6 .
- the housing 10 forms an outer contour of the image forming apparatus 1 .
- the scanner unit 2 reads image information of an object to be copied as the light and dark of the light to generate an image signal.
- the scanner unit 2 outputs the generated image signal to the image forming unit 3 .
- the image forming unit 3 forms an output image (hereinafter referred to as a toner image) by a recording agent such as toner on the basis of the image signal received from the scanner unit 2 or an image signal received from the outside.
- the image forming unit 3 transfers the toner image onto the surface of the sheet S.
- the image forming unit 3 heats and pressurizes the toner image on the surface of the sheet S to fix the toner image to the sheet S. The details of the image forming unit 3 will be described later.
- the sheet supply unit 4 supplies the sheet S to the conveying unit 5 in accordance with the timing at which the image forming unit 3 forms the toner image.
- the sheet supply unit 4 includes a sheet storage unit 20 and a pickup roller 21 .
- the sheet storage unit 20 accommodates the sheet S of a predetermined size and type.
- the pickup roller 21 takes out the sheets S one by one from the sheet storage unit 20 .
- the pickup roller 21 supplies the taken-out sheet S to the conveying unit 5 .
- the conveying unit 5 conveys the sheet S supplied from the sheet supply unit 4 to the image forming unit 3 .
- the conveying unit 5 includes a conveying roller 23 and a registration roller 24 .
- the conveying roller 23 conveys the sheet S supplied from the pickup roller 21 to the registration roller 24 .
- the conveying roller 23 presses the leading end of the sheet S in the conveying direction against the nip N of the registration roller 24 .
- the registration roller 24 bends the sheet S in the nip N to thereby adjust the position of the leading edge of the sheet S in the conveying direction.
- the registration roller 24 conveys the sheet S in accordance with the timing at which the image forming unit 3 transfers the toner image to the sheet S.
- the image forming unit 3 includes a plurality of image forming units ( 25 Y, 25 M, 25 C, and 25 K), a laser scanning unit 26 , an intermediate transfer belt 27 , a transfer unit 28 , and a fixing unit 30 .
- Each of the image forming units 25 includes a photosensitive drum 25 d .
- Each of the image forming units 25 forms a toner image corresponding to the image signal from the scanner unit 2 or an external device on the photosensitive drum 25 d .
- the plurality of image forming units 25 Y, 25 M, 25 C and 25 K form toner images of yellow, magenta, cyan and black toners, respectively.
- a charger, a developing device, and the like are disposed around the photosensitive drum 25 d of each of the image forming units 25 Y, 25 M, 25 C, and 25 K.
- the charging device charges the surface of the photosensitive drum 25 d .
- the developing device of each of the image forming units 25 Y, 25 M, 25 C, and 25 K contains developer containing one of yellow, magenta, cyan and black toners.
- the developing device develops the electrostatic latent image on the photosensitive drum 25 d .
- a toner image is formed by the toner of each color on the corresponding photosensitive drum 25 d.
- the laser scanning unit 26 scans the charged photosensitive drum 25 d with the laser beam L to expose the photosensitive drum 25 d .
- the laser scanning unit 26 exposes the photosensitive drums 25 d of the image forming units 25 Y, 25 M, 25 C and 25 K of the respective colors with the respective laser beams LY, LM, LC and LK. In this manner, the laser scanning unit 26 forms an electrostatic latent image on the photosensitive drum 25 d.
- the toner image on the surface of the photosensitive drum 25 d is primarily transferred onto the intermediate transfer belt 27 .
- the transfer portion 28 transfers the toner image primarily transferred onto the intermediate transfer belt 27 onto the surface of the sheet S at the secondary transfer position.
- the fixing unit 30 heats and pressurizes the toner image transferred to the sheet S to fix the toner image on the sheet S. The details of the fixing unit 30 will be described later.
- the reversing unit 9 reverses the sheet S to form an image on the back surface of the sheet S.
- the reversing unit 9 reverses the sheet S discharged from the fixing unit 30 by switch-back.
- the reversing unit 9 conveys the reversed sheet S toward the registration roller 24 .
- the sheet discharge tray 7 supports the sheet S that has been ejected with an image formed thereon.
- the control panel 8 is a part of an input unit for inputting information for an operator to operate the image forming apparatus 1 .
- the control panel 8 includes a touch panel and various hardware keys.
- the controller 6 controls each of the components installed in the image forming apparatus 1 . The details of the controller 6 will be described later.
- FIG. 2 is a hardware configuration diagram of an image forming apparatus according to an embodiment of the present invention.
- the image forming apparatus 1 includes a CPU (Central Processing Unit) 91 , a memory 92 , and an auxiliary storage device 93 connected to each other via a bus, and executes a program.
- the image forming apparatus 1 includes the scanner unit 2 , the image forming unit 3 , the sheet supply unit 4 , the forcing unit 5 , the reversing unit 9 , the control panel 8 , and a communication unit 90 .
- a CPU Central Processing Unit
- the CPU 91 is a component of the controller 6 and executes programs stored in the memory 92 and the auxiliary storage device 93 to achieve each function of the image forming apparatus 1 .
- the auxiliary storage device 93 is a storage device such as a magnetic hard disk device or a semiconductor storage device.
- the auxiliary storage device 93 stores information.
- the communication unit 90 includes a communication interface for communicating with an external device via a network.
- FIG. 3 is a front sectional view of the fixing unit 30 .
- the fixing unit 30 includes a pressing roller 30 p and a film unit 30 h.
- the pressing roller 30 p forms a nip N with the film unit 30 h .
- the pressing roller 30 p pressurizes the toner image on the sheet S that has entered into the nip N.
- the pressing roller 30 p rotates and conveys the sheet S.
- the pressure roller 30 p includes a core metal 32 , an elastic layer 33 , and a release layer (not shown).
- the core metal 32 is formed in a cylindrical shape by a metal material such as stainless steel or the like. Both end portions in the axial direction of the core metal 32 are supported to be rotatable.
- the core metal 32 is driven to rotate by a motor (not shown).
- the core metal 32 comes into contact with a cam member (not shown). The cam member is rotated to move the core metal 32 toward and away from the film unit 30 h.
- the elastic layer 33 is formed of an elastic material such as silicone rubber.
- the elastic layer 33 is formed to have a constant thickness on the outer peripheral surface of the core metal 32 .
- the release layer (not shown) 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 33 . It is preferable that the hardness of the outer circumferential surface of the pressure roller 30 p is between 40° and 70° under a load of 9.8N by an ASKER-C hardness meter. As a result, the area of the nip N and the durability of the pressing roller 30 p are secured.
- the pressing roller 30 p is able to move toward and away from the film unit 30 h by the rotation of the cam member.
- a nip N is formed.
- the sheet S can be removed by separating the pressure roller 30 p from the film unit 30 h .
- the pressure roller 30 p is moved away from the film unit 30 h , thereby preventing plastic deformation of the cylindrical film 35 .
- the pressure roller 30 p is rotated by a motor.
- the cylindrical film 35 of the film unit 30 h is driven to rotate.
- the pressing roller 30 p conveys the sheet S in the conveying direction W by rotating the sheet S in a state in which the sheet S is placed in the nip N.
- the film unit 30 h heats the toner image of the sheet S that has entered the nip N.
- the film unit 30 h includes the cylindrical film 35 , a heater unit 40 , a heat conductor 49 , a support member 36 , a stay 38 , a heater thermometer 62 , a thermostat 68 , and a film thermometer 64 .
- the cylindrical film 35 is formed in a cylindrical shape.
- the cylindrical film 35 has a base layer, an elastic layer, and a release layer in this order from the inner peripheral side.
- the base layer is formed in a cylindrical shape by a material such as nickel (Ni) or the like.
- the elastic layer is laminated and arranged on the outer peripheral surface of the base layer.
- the elastic layer is formed of an elastic material such as silicone rubber.
- the release layer is laminated and arranged on the outer peripheral surface of the elastic layer.
- the release layer is formed of a material such as a PFA resin.
- FIG. 4 is a front sectional view of the heater unit 40 taken along the line IV-IV in FIG. 5 .
- FIG. 5 is a bottom view of the heater unit 40 (i.e., viewed from the +z direction).
- the heater unit 40 includes a substrate 41 , a heating element set 45 , and a wiring set 55 .
- the substrate 41 is made of a metal material such as stainless steel, a ceramic material such as aluminum nitride, or the like.
- the substrate 41 is formed in an elongated rectangular plate shape.
- the substrate 41 is disposed radially inward of the cylindrical film 35 .
- the longitudinal direction corresponds to the axial direction of the cylindrical film 35 .
- the x direction, the y direction, and the z direction are defined as follows.
- the y direction is the longitudinal direction of the substrate 41 .
- the +y direction is a direction from a central heating element 45 a to a first end heating element 45 b 1 .
- the x direction is the short direction of the substrate 41
- the +x direction is the transport direction (i.e., downstream side) of the sheet S.
- the z direction is the normal direction of the substrate 41
- the +z direction is the direction in which the heating element set 45 is arranged with respect to the substrate 41 .
- An insulating layer 43 is formed on the surface of the substrate 41 in the +z direction by a glass material or the like.
- the heating element set 45 is arranged on the substrate 41 .
- the heating element set 45 is formed on the surface of the insulating layer 43 in the +z direction, as shown in FIG. 4 .
- the heating element set 45 is formed of a silver-palladium alloy or the like.
- the heating element set 45 has a rectangular shape in which the y direction is the longitudinal direction and the x direction is the short direction.
- the heating element set 45 includes a plurality of heating elements 45 b 1 , 45 a and 45 b 2 provided along the y direction.
- the heating element set 45 includes a first end heating element 45 b 1 , a central heating element 45 a , and a second end heating element 45 b 2 arranged side by side in the y direction.
- the central heating element 45 a is disposed in the central portion of the heating element set 45 in the y direction.
- the central heating element 45 a may be composed of a combination of a plurality of small heat-generating elements arranged side by side in the y direction.
- the first end heating element 45 b 1 is located at the +y direction end of central heating element 45 a and at the +y direction end of heating element set 45 .
- the second end heating element 45 b 2 is located in the ⁇ y direction of the central heating element 45 a and at the end of the heating element set 45 in the ⁇ y direction.
- the boundary between the central heating element 45 a and the first end heating element 45 b 1 may be arranged parallel to the x direction, and may be arranged to intersect with the x direction. The same applies to the boundary line between the central heating element 45 a and the second end heating element 45 b 2 .
- the heating element set 45 generates heat by energization.
- the electric resistance value of the central heating element 45 a is smaller than the electric resistance value of the first end heating element 45 b 1 and the second end heating element 45 b 2 .
- the sheet S having a small width in the y direction passes through the central portion in the y direction of the fixing unit 30 .
- the controller 6 causes only the central heating element 45 a to generate heat.
- the controller 6 generates heat in the entirety of the heating element set 45 . Therefore, the central heating element 45 a and the first end heating element 45 b 1 and the second end heating element 45 b 2 are controlled in heat generation independently of each other. Also, the first end heating element 45 b 1 and the second end heating element 45 b 2 are similarly controlled in heat generation.
- the wiring set 55 is made of a metal material such as silver.
- the wiring set 55 includes a central contact 52 a , a central portion wiring 53 a , an end contact 52 b , a first end wiring 53 b 1 , a second end wiring 53 b 2 , a common contact 58 , and a common wiring 57 .
- the central contact 52 a is arranged on the ⁇ y direction side of the heating element set 45 .
- the central portion wiring 53 a is arranged on the +x direction side of the heating element set 45 .
- the central portion wiring 53 a connects the side in the +x direction of the central heating element 45 a and the central portion contact 52 a.
- the end contact 52 b is arranged on the ⁇ y direction side of the central contact 52 a .
- the first end wiring 53 b 1 extends along the side in the +x direction of the heating element set 45 and on the +x direction side of the central portion wiring 53 a .
- the first end wiring 53 b 1 connects the end of the first end heating element 45 b 1 in the +x direction and the end of the end contact 52 b in the +x direction.
- the second end wiring 53 b 2 extends along the side in the +x direction of the heating element set 45 and on the ⁇ x direction side of the central portion wiring 53 a .
- the second end wiring 53 b 2 connects the end of the second end heating element 45 b 2 in the +x direction and the end of the end contact 52 b in the ⁇ x direction.
- the common contact 58 is arranged at the end in the +y direction of the heating element set 45 .
- the common wiring 57 extends along the side in the ⁇ x direction of the heating element set 45 .
- the common wiring 57 connects the end sides in the ⁇ x direction of the central heating element 45 a , the first end heating element 45 b 1 and the second end heating element 45 b 2 , and the common contact 58 .
- the second end wiring 53 b 2 , the central portion wiring 53 a and the first end portion wiring 53 b 1 extend along the side in the +x direction of the heating element set 45 .
- the common wiring 57 extends along the side in the ⁇ x direction of the heating element set 45 . Therefore, the center 45 c in the x direction of the heating element set 45 is arranged on the ⁇ x direction side with respect to the center 41 c in the x direction of the substrate 41 .
- a straight line CL connecting the center pc of the pressure roller 30 p and the center hc of the film unit 30 h is defined.
- the center 41 c in the x direction of the substrate 41 is arranged in the +x direction from the straight line CL.
- the substrate 41 extends in the +x direction of the nip N, so that the sheet S that has passed through the nip N is easily peeled off from the film unit 30 h.
- the center 45 c of the heating element set 45 in the x direction is disposed on the straight line CL.
- the heating element set 45 is contained entirely within the region of the nip N and is located at the center of the nip N. Thus, the heat distribution of the nip N becomes uniform, and the sheet S passing through the nip N is uniformly heated.
- the heating element set 45 and the wiring set 55 are formed on the surface of the insulating layer 43 in the +z direction.
- a protective layer 46 is formed of a glass material or the like so as to cover the heating element set 45 and the wiring set 55 .
- the protective layer 46 improves the sliding property between the heater unit 40 and the cylindrical film 35 .
- the heater unit 40 is disposed inside the cylindrical film 35 .
- a lubricant (not shown) is applied to the inner peripheral surface of the cylindrical film 35 .
- the heater unit 40 is brought into contact with the inner peripheral surface of the cylindrical film 35 through the lubricant.
- the viscosity of the lubricant is lowered.
- the sliding property between the heater unit 40 and the cylindrical film 35 is secured.
- the heat conductor 49 is formed of a metal material having a high thermal conductivity, such as copper.
- the outer shape of the heat conductor 49 is equivalent to the outer shape of the substrate 41 of the heater unit 40 .
- the heat conductor 49 is disposed in contact with the surface of the heater unit 40 in the ⁇ z direction.
- the support member 36 is made of a resin material such as a liquid crystal polymer.
- the support member 36 is disposed so as to cover the side in the ⁇ z direction of the heater unit 40 and the both sides in the x direction of the heater unit 40 .
- the support member 36 supports the heater unit 40 via a heat conductor 49 . Rounded chamfering is formed at both end portions in the x direction of the support member 36 .
- the support member 36 supports the inner peripheral surface of the cylindrical film 35 at both end portions in the x direction of the heater unit 40 .
- the stay 38 is formed of a steel sheet material or the like.
- a cross section perpendicular to the y direction of the stay 38 is formed in a U shape.
- the stay 38 is mounted on the surface in the ⁇ z direction of the support member 36 so as to block the opening of the U shape by the support member 36 .
- the stay 38 extends in the y direction. Both end portions of the stay 38 in the y direction in the y direction are fixed to the housing of the image forming apparatus 1 .
- the film unit 30 h is supported by the image forming apparatus 1 .
- the stay 38 improves the bending rigidity of the film unit 30 h .
- a flange (not shown) for restricting the movement of the cylindrical film 35 in the y direction is mounted in the vicinity of both end portions in the y direction of the stay 38 .
- the heater thermometer 62 is arranged in the ⁇ z direction of the heater unit 40 with the heat conductor 49 interposed therebetween.
- the heater thermometer is mounted on and supported by a surface in the ⁇ z direction of the support member 36 .
- the temperature sensitive element of the heater thermometer 62 contacts the heat conductor 49 through a hole passing through the support member 36 in the z direction.
- the heater thermometer 62 measures the temperature of the heater unit 40 via the heat conductor 49 .
- the thermostat 68 is arranged similarly to the heater thermometer 62 .
- the thermostat 68 is incorporated into an electrical circuit, which will be described later.
- the thermostat 68 cuts off the power supply to the heating element set 45 .
- FIG. 6 is a top view of the heater thermometer and thermostat (i.e., viewed from the ⁇ z direction).
- the description of the supporting member 36 is omitted.
- the following description of the arrangement of the heater thermometer, thermostat and film thermometer is used to describe the arrangement of the respective temperature sensitive elements.
- a plurality of heater thermometers 62 ( 62 a , 62 b ) are arranged in the heating element set 45 side by side along the y direction.
- the plurality of heater thermometers 62 are disposed at the center of the heating element set 45 in the x direction. That is, when viewed from the z direction, the plurality of heater thermometers 62 and the heating element set 45 overlap at least partially.
- the plurality of thermostats 68 ( 68 a , 68 b ) are also arranged in the same manner as the plurality of heater thermometers 62 described above.
- a plurality of heater thermometers 62 include a central heater thermometer 62 a and an end heater thermometer 62 b.
- the central heater thermometer 62 a measures the temperature of the central heating element 45 a .
- the central heater thermometer 62 a is positioned within the central heating element 45 a . That is, when viewed from the z direction, the central heater thermometer 62 a and the central heating element 45 a overlap each other.
- the end heater thermometer 62 b measures the temperature of the second end heating element 45 b 2 .
- the first end heating element 45 b 1 and the second end heating element 45 b 2 are similarly controlled in heat generation. Therefore, the temperature of the first end heating element 45 b 1 and the temperature of the second end heating element 45 b 2 are equal to each other.
- the end heater thermometer 62 b is located within a range of second end heating element 45 b 2 . That is, the end heater thermometer 62 b and the second end heating element 45 b 2 overlap each other when viewed from the direction z.
- the plurality of thermostats 68 include a central thermostat 68 a and an end thermostat 68 b.
- the central thermostat 68 a interrupts the energization of the heating element set 45 when the temperature of the central heating element 45 a exceeds the predetermined temperature.
- the central thermostat 68 a is positioned within the range of the central heating element 45 a . That is, when viewed in the z direction, the central thermostat 68 a and the central heating element 45 a overlap each other.
- the end thermostat 68 b interrupts energization of the heating element set 45 when the temperature of the first end heating element 45 b 1 exceeds a predetermined temperature.
- the first end heating element 45 b 1 and the second end heating element 45 b 2 are similarly controlled in heat generation. Therefore, the temperature of the first end heating element 45 b 1 and the temperature of the second end heating element 45 b 2 are equal to each other.
- the end thermostat 68 b is located within a range of the first end heating element 45 b 1 . That is, when viewed from the z direction, the end thermostat 68 b and the first end heating element 45 b 1 overlap each other.
- the central heater thermometer 62 a and the central thermostat thermometer 68 a are disposed on the central heating element 45 a so as to measure the temperature of the central heating element 45 a .
- the power supply to the heating element set 45 is interrupted.
- the end heater thermometer 62 b and the end thermostat 68 b are disposed on the first end heating element 45 b 1 and the second end heating element 45 b 2 .
- the temperatures of the first end heating element 45 b 1 and the second end heating element 45 b 2 are measured.
- the power supply to the heating element set 45 is interrupted.
- the plurality of heaters 62 and the plurality of thermostats 68 are alternately arranged along the y direction.
- the first end heating element 45 b 1 is arranged on the +y direction side of the central heating element 45 a .
- the end thermostat 68 b is disposed within the first end heating element 45 b 1 .
- the central heater thermometer 62 a is arranged on the +y direction side with respect to the central of the central heating element 45 a .
- the central thermostat 68 a is arranged on the ⁇ y direction side with respect to the central of central heating element 45 a .
- the second end heating element 45 b 2 is arranged on the ⁇ y direction side of the central heating element 45 a .
- the end heater thermometer 62 b is located within the second end heating element 45 b 2 .
- the end thermostat 68 b , the central heater thermometer 62 a , the central thermostat 68 a and the end heater thermometer 62 b are arranged in this order along the ⁇ y direction.
- thermostat 68 utilizes a bimetal curve deformation with temperature changes to connect and disconnect the electrical circuit.
- the thermostat is formed to be elongated in conformity to the shape of the bimetal. Terminals extend outward from both end portions in the longitudinal direction of the thermostat 68 . Each terminal is connected to a connector of external wiring. Therefore, it is necessary to secure a space outside the thermostat 68 in the longitudinal direction. Since there is no space at both ends in the x direction of the fixing unit 30 , the longitudinal direction of the thermostat 68 is arranged along the y direction. In this case, when a plurality of thermostats 68 are arranged adjacent to each other in the y direction, it becomes difficult to secure a connection space of the external wiring.
- the plurality of heaters 62 and the plurality of thermostats 68 are alternately arranged along the y direction.
- a heater thermometer 62 is disposed adjacent to each thermostat 68 in the y direction. Therefore, it is possible to secure a space for connecting external wiring to the thermostat 68 .
- the degree of freedom in the layout in the y direction of the thermostat 68 and the heater thermometer 62 is increased. This allows the thermostat 68 and heater thermometer 62 to be positioned at an optimal position to control the temperature of the fixing unit 30 . Further, it is easy to separate the alternating current wiring connected to the plurality of thermostats 68 from the direct current wiring connected to the plurality of heater thermometers 62 . As a result, noise in the electric circuit is suppressed.
- the film thermometer 64 is disposed inside the cylindrical film 35 and on the +x direction side of the heater unit 40 .
- the film thermometer 64 contacts the inner peripheral surface of the cylindrical film 35 to measure the temperature of the cylindrical film 35 .
- FIG. 7 is an electric circuit diagram of the fixing unit according to one embodiment.
- the bottom view of the heater unit 40 shown in FIG. 5 is located at the top of FIG. 7
- the plan view of the substrate 41 shown in FIG. 6 is arranged at the bottom of FIG. 7 .
- FIG. 7 also shows a plurality of film thermometers 64 along with a cross section of the cylindrical film 35 .
- the plurality of film thermometers 64 includes a central film thermometer 64 a and an end film thermometer 64 b.
- the central film thermometer 64 a comes into contact with the central portion of the cylindrical film 35 in the y direction.
- the central film thermometer 64 a contacts the cylindrical film 35 within the range in the y-direction of the central heating element 45 a .
- the central film thermometer 64 a measures the temperature of the central portion in the y direction of the cylindrical film 35 .
- the end film thermometer 64 b contacts the end of cylindrical film 35 in the ⁇ y direction.
- the end film thermometer 64 b contacts the cylindrical film 35 within the range in the y-direction of the second end heating element 45 b 2 .
- the end film thermometer 64 b measures the temperature at the end of the cylindrical film 35 in the ⁇ y direction.
- the first end heating element 45 b 1 and the second end heating element 45 b 2 are similarly controlled in heat generation. Therefore, the temperature at the end portion in the ⁇ y direction of the cylindrical film 35 and the temperature at the end portion in the +y direction are identical.
- a power supply 95 is electrically connected to the central contact point 52 a via a central triac 96 a .
- the power supply 95 is electrically connected to the end contact 52 b via an end triac 96 b .
- the CPU 91 controls ON/OFF of the central triac 96 a and the end triac 96 b independently of each other.
- the CPU 91 turns on the central triac 96 a
- power is supplied to the central heating element 45 a from the power supply 95 .
- the central heating element 45 a generates heat.
- the CPU 91 turns on the end triac 96 b
- the power is supplied from the power supply 95 to the first end heating element 45 b 1 and the second end heating element 45 b 2 .
- the first end heating element 45 b 1 and the second end heating element 45 b 2 generate heat.
- the central heating element 45 a and the first end heating element 45 b 1 and the second end heating element 45 b 2 are controlled in heat generation independently from each other.
- the central heating element 45 a , the first end heating element 45 b 1 and the second end heating element 45 b 2 are connected in parallel with respect to the power supply 95 .
- the power supply 95 is electrically connected to the common contact 58 via the central thermostat 68 a and the end thermostat 68 b .
- the central thermostat 68 a and the end thermostat 68 b are connected in series.
- the central thermostat 68 a shuts off the power supply from the power supply 95 to the heating element set 45 .
- the end thermostat 68 b When the temperature of the first end heating element 45 b 1 rises abnormally, the detected temperature of the end thermostat 68 b exceeds a predetermined temperature. At this time, the end thermostat 68 b shuts off the power supply from the power supply 95 to the heating element set 45 .
- the first end heating element 45 b 1 and the second end heating element 45 b 2 are similarly controlled in heat generation. Therefore, when the temperature of the second end heating element 45 b 2 rises abnormally, the temperature of the first end heating element 45 b 1 also increases. Accordingly, in the case where the temperature of the second end heating element 45 b 2 abnormally rises, the end thermostat 68 b also shuts off the power supplied from the power supply 95 to the whole of heating element set 45 .
- the CPU 91 of the controller 6 acquires the temperature of the central heating element 45 a from the central heater thermometer 62 a .
- the CPU 91 acquires the temperature of the second end heating element 45 b 2 from the end heater thermometer 62 b .
- the temperature of the second end heating element 45 b 2 is equal to the temperature of the first end heating element 45 b 1 .
- the CPU 91 controls the heater thermometer 62 to measure the temperature of the heating element set 45 .
- the CPU 91 causes the heating element set 45 to generate heat only for a short time. Thereafter, the CPU 91 controls the pressure roller 30 p to start the rotation.
- the heat generated by the heating element set 45 lowers the viscosity of lubricant applied to the inner peripheral surface of the cylindrical film 35 .
- the sliding property between the heater unit 40 and the cylindrical film 35 at the start of the rotation of the pressure roller 30 p is ensured.
- the CPU 91 controls the central film thermometer 64 a to measure the temperature of the central portion in the y direction of the cylindrical film 35 .
- the CPU 91 controls the end film thermometer 64 b to measure the temperature at the end portion in the ⁇ y direction of the cylindrical film.
- the temperature of the end of the cylindrical film 35 in the ⁇ y direction is equal to the temperature of the end of the cylindrical film 35 in the +y direction.
- the temperatures of the central portion and the end portion in the y direction of the cylindrical film 35 are measured during the operation of the fixing unit 30 .
- the CPU 91 controls the phase or wave number of electric power supplied to the heating element set 45 by the central triac 96 a and the end triac 96 b .
- the CPU 91 controls the energization to the central heating element 45 a based on the temperature measurement result at the central portion in the y direction of the cylindrical film 35 .
- the CPU 91 controls the energization to the first end heating element 45 b 1 and the second end heating element 45 b 2 based on the temperature measurement result at the end portion in the y direction of the cylindrical film 35 .
- the fixing unit 30 of the embodiment includes the cylindrical film 35 , the heating element set 45 , the plurality of heater thermometers 62 , and the plurality of thermostats 68 .
- the heating element set 45 is disposed inside the cylindrical film 35 , and the axial direction of the cylindrical film 35 is taken as the longitudinal direction of the cylindrical film 35 .
- the plurality of heaters 62 and the plurality of thermostats 68 are alternately arranged along the longitudinal direction of the heating element set 45 within the heating element set 45 .
- the plurality of heaters 62 and the plurality of thermostats 68 are alternately arranged along the longitudinal direction of the cylindrical film 35 . Therefore, it is possible to secure a space for connecting external wiring to the thermostat 68 at both sides in the Y direction of the substrate 41 . In addition, the degree of freedom in the layout on the substrate 41 in the y direction of the thermostat 68 and the heater thermometer 62 is increased. Thus, the thermostat 68 and the heater thermometer 62 are arranged at an optimal position to properly control the heating temperature.
- the fixing unit 30 has the substrate 41 .
- the substrate 41 is disposed inside the cylindrical film 35 , and the axial direction of the cylindrical film 35 corresponds to the longitudinal direction of the substrate 41 .
- the heating element set 45 is disposed on the substrate 41 , and the short-side direction of the substrate 41 is defined as the short-side direction of the heating element set 45 .
- the center in the lateral direction of the heating element set 45 is disposed at a position different from the center in the short-side direction of the substrate 41 .
- a plurality of wirings can be arranged on one side in the lateral direction of the heating element set 45 . As a result, heat generation of a plurality of heating elements included in the heating element set 45 can be controlled independently of each other.
- the plurality of heaters 62 and the plurality of thermostats 68 are disposed at the center in the short-side direction of the heating element set 45 .
- the plurality of heaters 62 and the plurality of thermostats 68 can accurately measure or detect the temperature of the heating element set 45 .
- the heating element set 45 includes the central heating element 45 a and the first end heating element 45 b 1 and the second end heating element 45 b 2 .
- the central heating element 45 a is arranged at the center of the substrate 41 in the longitudinal direction.
- the first end heating element 45 b 1 and the second end heating element 45 b 2 are disposed at both ends in the longitudinal direction of the substrate 41 , and heat generation is controlled independently of the central heating element 45 a .
- the first end heating element 45 b 1 and the second end heating element 45 b 2 are similarly controlled in heat generation.
- the heating temperature can be appropriately controlled.
- the plurality of heater thermometers 62 include the central heater thermometer 62 a and the end heater thermometer 62 b .
- the plurality of thermostats 68 include the central thermostat 68 a and the end thermostat 68 b .
- the central heater thermometer 62 a and the central thermostat 68 a are positioned within the central heating element 45 a .
- the end thermostat 68 b is located within a range of the first end heating element 45 b 1 .
- the end heater thermometer 62 b is located within a range of the second end heating element 45 b 2 .
- the central heater thermometer 62 a measures the temperature of the central heating element 45 a .
- the temperature of the central heating element 45 a measured by the central thermostat 68 a exceeds the predetermined temperature, the power supply to the heating element set 45 is interrupted.
- the first end heating element 45 b 1 and the second end heating element 45 b 2 are similarly controlled in heat generation. Therefore, the temperature of the first end heating element 45 b 1 and the temperature of the second end heating element 45 b 2 are equal to each other.
- the end heater thermometer 62 b measures the temperature of the second end heating element 45 b 2 . When the temperature of the first end heating element 45 b 2 exceeds the predetermined temperature by the end thermostat 68 b , the power supply to the heating element set 45 is interrupted.
- the temperature of all heating elements included in the heating element set 45 is measured.
- the energization of the heating element set 45 is interrupted.
- the image forming apparatus 1 of the embodiment comprises the fixing unit 30 as described above.
- the fixing unit 30 is capable of appropriately controlling the heating temperature. Accordingly, the image forming apparatus 1 can improve image quality.
- the heating element set 45 of the aforementioned embodiments includes three heating elements (i.e., the central heating element 45 a , the first end heating element 45 b 1 , and the second end heating element 45 b 2 ). In contrast, the number of heating elements included in the heating element set 45 may be one or two or equal to or more than 4.
- the heater thermometer 62 of the aforementioned embodiments includes two heater thermometers (i.e., the central heater thermometer 62 a and the end heater thermometer 62 b ). In contrast, the number of heater thermometers 62 may be equal to or more than 3.
- the plurality of thermostats 68 of the embodiment include two thermostats (i.e., the central thermostat 68 a and the end thermostat 68 b ). In contrast, the number of the plurality of thermostats 68 may be equal to or more than three.
- the image forming apparatus 1 and the fixing unit 30 are described as examples of an image processing apparatus and a heating apparatus.
- Another example of the image processing apparatus is a decoloring apparatus having a decoloring unit.
- the decoloring apparatus performs a process of decoloring (i.e., erasing) an image formed on a sheet by a decolorable toner.
- the decoloring unit heats the decolorable toner image formed on the sheet passing through the nip to decolorize the toner image.
- the plurality of heaters 62 and the plurality of thermostats 68 are alternately arranged along the longitudinal direction of the heating element set 45 . As a result, the heating temperature can be appropriately controlled.
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Fixing For Electrophotography (AREA)
- Control Or Security For Electrophotography (AREA)
- Control Of Resistance Heating (AREA)
Abstract
A fixing device which heats an image formed on a sheet to fix the image thereon, includes a cylindrical film supported in a rotatable manner and having an outer circumferential surface that comes into contact with the sheet, and a heater unit provided in an inner space of the cylindrical film to heat an inner circumferential surface thereof. The heater unit includes a plurality of first heating elements disposed along a longitudinal direction of the cylindrical film, and a first temperature sensor configured to measure a temperature of one of the plurality of first heating elements. The plurality of first heating elements and the first temperature sensor are connected in series by a first wiring.
Description
- This application is a continuation of U.S. patent application Ser. No. 17/322,755, filed May 17, 2021, which is a continuation of U.S. patent application Ser. No. 16/734,215, filed Jan. 3, 2020, now U.S. Pat. No. 11,042,109, issued on Jun. 22, 2021, which is based upon and claims the benefit of priority from Japanese Patent Application No. 2019-021852, filed on Feb. 8, 2019, the entire contents of which are incorporated herein by reference.
- An embodiment of the present invention relates to a heating device and an image processing apparatus.
- An image forming apparatus for forming an image on a sheet includes a heating apparatus for fixing a toner (i.e., recording agent) to the sheet. Heating temperature is required to be appropriately controlled in the heating apparatus.
-
FIG. 1 is a schematic configuration diagram of an image forming apparatus according to one embodiment. -
FIG. 2 is a hardware configuration diagram of the image forming apparatus. -
FIG. 3 is a front sectional view of a fixing unit according to one embodiment. -
FIG. 4 is a front sectional view of a heater unit of the fixing unit. -
FIG. 5 is a bottom view of the heater unit. -
FIG. 6 is a plan view of a heater thermometer and a thermostat. -
FIG. 7 is an electric circuit diagram of the fixing unit. - A fixing device according to an embodiment, which heats an image formed on a sheet to fix the image thereon, includes a cylindrical film supported in a rotatable manner and having an outer circumferential surface that comes into contact with the sheet, and a heater unit provided in an inner space of the cylindrical film to heat an inner circumferential surface thereof. The heater unit includes a plurality of first heating elements disposed along a longitudinal direction of the cylindrical film, and a first temperature sensor configured to measure a temperature of one of the plurality of first heating elements. The plurality of first heating elements and the first temperature sensor are connected in series by a first wiring.
- Hereinafter, as an example of an image processing apparatus and a heating apparatus, an image forming apparatus and a fixing unit will be described with reference to the drawings.
-
FIG. 1 is a schematic configuration diagram of an image forming apparatus according to one embodiment of the present invention. The image forming apparatus 1 performs processing for forming an image on a sheet of paper S. The image forming apparatus 1 includes ahousing 10, ascanner unit 2, animage forming unit 3, a sheet supply unit 4, a forcingunit 5, apaper discharge tray 7, areversing unit 9, acontrol panel 8, and acontroller 6. - The
housing 10 forms an outer contour of the image forming apparatus 1. Thescanner unit 2 reads image information of an object to be copied as the light and dark of the light to generate an image signal. Thescanner unit 2 outputs the generated image signal to theimage forming unit 3. Theimage forming unit 3 forms an output image (hereinafter referred to as a toner image) by a recording agent such as toner on the basis of the image signal received from thescanner unit 2 or an image signal received from the outside. Theimage forming unit 3 transfers the toner image onto the surface of the sheet S. Theimage forming unit 3 heats and pressurizes the toner image on the surface of the sheet S to fix the toner image to the sheet S. The details of theimage forming unit 3 will be described later. - The sheet supply unit 4 supplies the sheet S to the
conveying unit 5 in accordance with the timing at which theimage forming unit 3 forms the toner image. The sheet supply unit 4 includes asheet storage unit 20 and apickup roller 21. Thesheet storage unit 20 accommodates the sheet S of a predetermined size and type. Thepickup roller 21 takes out the sheets S one by one from thesheet storage unit 20. Thepickup roller 21 supplies the taken-out sheet S to theconveying unit 5. - The
conveying unit 5 conveys the sheet S supplied from the sheet supply unit 4 to theimage forming unit 3. Theconveying unit 5 includes aconveying roller 23 and aregistration roller 24. Theconveying roller 23 conveys the sheet S supplied from thepickup roller 21 to theregistration roller 24. Theconveying roller 23 presses the leading end of the sheet S in the conveying direction against the nip N of theregistration roller 24. Theregistration roller 24 bends the sheet S in the nip N to thereby adjust the position of the leading edge of the sheet S in the conveying direction. Theregistration roller 24 conveys the sheet S in accordance with the timing at which theimage forming unit 3 transfers the toner image to the sheet S. - The
image forming unit 3 will be described. Theimage forming unit 3 includes a plurality of image forming units (25Y, 25M, 25C, and 25K), alaser scanning unit 26, anintermediate transfer belt 27, atransfer unit 28, and afixing unit 30. Each of the image forming units 25 includes aphotosensitive drum 25 d. Each of the image forming units 25 forms a toner image corresponding to the image signal from thescanner unit 2 or an external device on thephotosensitive drum 25 d. The plurality of image forming units 25Y, 25M, 25C and 25K form toner images of yellow, magenta, cyan and black toners, respectively. - A charger, a developing device, and the like are disposed around the
photosensitive drum 25 d of each of the image forming units 25Y, 25M, 25C, and 25K. The charging device charges the surface of thephotosensitive drum 25 d. The developing device of each of the image forming units 25Y, 25M, 25C, and 25K contains developer containing one of yellow, magenta, cyan and black toners. The developing device develops the electrostatic latent image on thephotosensitive drum 25 d. As a result, a toner image is formed by the toner of each color on the correspondingphotosensitive drum 25 d. - The
laser scanning unit 26 scans the chargedphotosensitive drum 25 d with the laser beam L to expose thephotosensitive drum 25 d. Thelaser scanning unit 26 exposes thephotosensitive drums 25 d of the image forming units 25Y, 25M, 25C and 25K of the respective colors with the respective laser beams LY, LM, LC and LK. In this manner, thelaser scanning unit 26 forms an electrostatic latent image on thephotosensitive drum 25 d. - The toner image on the surface of the
photosensitive drum 25 d is primarily transferred onto theintermediate transfer belt 27. Thetransfer portion 28 transfers the toner image primarily transferred onto theintermediate transfer belt 27 onto the surface of the sheet S at the secondary transfer position. Thefixing unit 30 heats and pressurizes the toner image transferred to the sheet S to fix the toner image on the sheet S. The details of thefixing unit 30 will be described later. - The
reversing unit 9 reverses the sheet S to form an image on the back surface of the sheet S. Thereversing unit 9 reverses the sheet S discharged from thefixing unit 30 by switch-back. The reversingunit 9 conveys the reversed sheet S toward theregistration roller 24. Thesheet discharge tray 7 supports the sheet S that has been ejected with an image formed thereon. Thecontrol panel 8 is a part of an input unit for inputting information for an operator to operate the image forming apparatus 1. Thecontrol panel 8 includes a touch panel and various hardware keys. Thecontroller 6 controls each of the components installed in the image forming apparatus 1. The details of thecontroller 6 will be described later. -
FIG. 2 is a hardware configuration diagram of an image forming apparatus according to an embodiment of the present invention. The image forming apparatus 1 includes a CPU (Central Processing Unit) 91, amemory 92, and anauxiliary storage device 93 connected to each other via a bus, and executes a program. As described above, the image forming apparatus 1 includes thescanner unit 2, theimage forming unit 3, the sheet supply unit 4, the forcingunit 5, the reversingunit 9, thecontrol panel 8, and acommunication unit 90. - The
CPU 91 is a component of thecontroller 6 and executes programs stored in thememory 92 and theauxiliary storage device 93 to achieve each function of the image forming apparatus 1. Theauxiliary storage device 93 is a storage device such as a magnetic hard disk device or a semiconductor storage device. Theauxiliary storage device 93 stores information. Thecommunication unit 90 includes a communication interface for communicating with an external device via a network. - The fixing
unit 30 will be described in detail.FIG. 3 is a front sectional view of the fixingunit 30. The fixingunit 30 includes apressing roller 30 p and afilm unit 30 h. - The
pressing roller 30 p forms a nip N with thefilm unit 30 h. Thepressing roller 30 p pressurizes the toner image on the sheet S that has entered into the nip N. Thepressing roller 30 p rotates and conveys the sheet S. Thepressure roller 30 p includes acore metal 32, anelastic layer 33, and a release layer (not shown). - The
core metal 32 is formed in a cylindrical shape by a metal material such as stainless steel or the like. Both end portions in the axial direction of thecore metal 32 are supported to be rotatable. Thecore metal 32 is driven to rotate by a motor (not shown). Thecore metal 32 comes into contact with a cam member (not shown). The cam member is rotated to move thecore metal 32 toward and away from thefilm unit 30 h. - The
elastic layer 33 is formed of an elastic material such as silicone rubber. Theelastic layer 33 is formed to have a constant thickness on the outer peripheral surface of thecore metal 32. The release layer (not shown) 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 theelastic layer 33. It is preferable that the hardness of the outer circumferential surface of thepressure roller 30 p is between 40° and 70° under a load of 9.8N by an ASKER-C hardness meter. As a result, the area of the nip N and the durability of thepressing roller 30 p are secured. - The
pressing roller 30 p is able to move toward and away from thefilm unit 30 h by the rotation of the cam member. When thepressing roller 30 p is brought close to thefilm unit 30 h and pressed by a pressing spring, a nip N is formed. On the other hand, when the sheet S is jammed in the fixingunit 30, the sheet S can be removed by separating thepressure roller 30 p from thefilm unit 30 h. In addition, in a state in which thecylindrical film 35 is stopped to rotate, such as in a sleep state, thepressure roller 30 p is moved away from thefilm unit 30 h, thereby preventing plastic deformation of thecylindrical film 35. - The
pressure roller 30 p is rotated by a motor. When thepressing roller 30 p rotates in a state where the nip N is formed, thecylindrical film 35 of thefilm unit 30 h is driven to rotate. Thepressing roller 30 p conveys the sheet S in the conveying direction W by rotating the sheet S in a state in which the sheet S is placed in the nip N. - The
film unit 30 h heats the toner image of the sheet S that has entered the nip N. Thefilm unit 30 h includes thecylindrical film 35, aheater unit 40, aheat conductor 49, asupport member 36, astay 38, a heater thermometer 62, a thermostat 68, and afilm thermometer 64. - The
cylindrical film 35 is formed in a cylindrical shape. Thecylindrical film 35 has a base layer, an elastic layer, and a release layer in this order from the inner peripheral side. The base layer is formed in a cylindrical shape by a material such as nickel (Ni) or the like. The elastic layer is laminated and arranged on the outer peripheral surface of the base layer. The elastic layer is formed of an elastic material such as silicone rubber. The release layer is laminated and arranged on the outer peripheral surface of the elastic layer. The release layer is formed of a material such as a PFA resin. -
FIG. 4 is a front sectional view of theheater unit 40 taken along the line IV-IV inFIG. 5 .FIG. 5 is a bottom view of the heater unit 40 (i.e., viewed from the +z direction). Theheater unit 40 includes asubstrate 41, a heating element set 45, and awiring set 55. - The
substrate 41 is made of a metal material such as stainless steel, a ceramic material such as aluminum nitride, or the like. Thesubstrate 41 is formed in an elongated rectangular plate shape. Thesubstrate 41 is disposed radially inward of thecylindrical film 35. In thesubstrate 41, the longitudinal direction corresponds to the axial direction of thecylindrical film 35. - In the present application, the x direction, the y direction, and the z direction are defined as follows. The y direction is the longitudinal direction of the
substrate 41. As will be described later, the +y direction is a direction from acentral heating element 45 a to a first end heating element 45 b 1. The x direction is the short direction of thesubstrate 41, and the +x direction is the transport direction (i.e., downstream side) of the sheet S. The z direction is the normal direction of thesubstrate 41, and the +z direction is the direction in which the heating element set 45 is arranged with respect to thesubstrate 41. An insulatinglayer 43 is formed on the surface of thesubstrate 41 in the +z direction by a glass material or the like. - The heating element set 45 is arranged on the
substrate 41. The heating element set 45 is formed on the surface of the insulatinglayer 43 in the +z direction, as shown inFIG. 4 . The heating element set 45 is formed of a silver-palladium alloy or the like. The heating element set 45 has a rectangular shape in which the y direction is the longitudinal direction and the x direction is the short direction. - As shown in
FIG. 5 , the heating element set 45 includes a plurality of heating elements 45b 1, 45 a and 45 b 2 provided along the y direction. The heating element set 45 includes a first end heating element 45 b 1, acentral heating element 45 a, and a second end heating element 45b 2 arranged side by side in the y direction. Thecentral heating element 45 a is disposed in the central portion of the heating element set 45 in the y direction. Thecentral heating element 45 a may be composed of a combination of a plurality of small heat-generating elements arranged side by side in the y direction. The first end heating element 45 b 1 is located at the +y direction end ofcentral heating element 45 a and at the +y direction end of heating element set 45. The second end heating element 45b 2 is located in the −y direction of thecentral heating element 45 a and at the end of the heating element set 45 in the −y direction. The boundary between thecentral heating element 45 a and the first end heating element 45 b 1 may be arranged parallel to the x direction, and may be arranged to intersect with the x direction. The same applies to the boundary line between thecentral heating element 45 a and the second end heating element 45b 2. - The heating element set 45 generates heat by energization. The electric resistance value of the
central heating element 45 a is smaller than the electric resistance value of the first end heating element 45 b 1 and the second end heating element 45b 2. - The sheet S having a small width in the y direction passes through the central portion in the y direction of the fixing
unit 30. In this case, thecontroller 6 causes only thecentral heating element 45 a to generate heat. On the other hand, in the case of the sheet S having a large width in the y direction, thecontroller 6 generates heat in the entirety of the heating element set 45. Therefore, thecentral heating element 45 a and the first end heating element 45 b 1 and the second end heating element 45b 2 are controlled in heat generation independently of each other. Also, the first end heating element 45 b 1 and the second end heating element 45b 2 are similarly controlled in heat generation. - The wiring set 55 is made of a metal material such as silver. The wiring set 55 includes a
central contact 52 a, acentral portion wiring 53 a, anend contact 52 b, a first end wiring 53 b 1, a second end wiring 53b 2, acommon contact 58, and acommon wiring 57. - The
central contact 52 a is arranged on the −y direction side of the heating element set 45. Thecentral portion wiring 53 a is arranged on the +x direction side of the heating element set 45. Thecentral portion wiring 53 a connects the side in the +x direction of thecentral heating element 45 a and thecentral portion contact 52 a. - The
end contact 52 b is arranged on the −y direction side of thecentral contact 52 a. The first end wiring 53 b 1 extends along the side in the +x direction of the heating element set 45 and on the +x direction side of thecentral portion wiring 53 a. The first end wiring 53 b 1 connects the end of the first end heating element 45 b 1 in the +x direction and the end of theend contact 52 b in the +x direction. The second end wiring 53b 2 extends along the side in the +x direction of the heating element set 45 and on the −x direction side of thecentral portion wiring 53 a. The second end wiring 53b 2 connects the end of the second end heating element 45b 2 in the +x direction and the end of theend contact 52 b in the −x direction. - The
common contact 58 is arranged at the end in the +y direction of the heating element set 45. Thecommon wiring 57 extends along the side in the −x direction of the heating element set 45. Thecommon wiring 57 connects the end sides in the −x direction of thecentral heating element 45 a, the first end heating element 45 b 1 and the second end heating element 45b 2, and thecommon contact 58. - In this manner, the second end wiring 53
b 2, thecentral portion wiring 53 a and the first end portion wiring 53 b 1 extend along the side in the +x direction of the heating element set 45. In contrast, only thecommon wiring 57 extends along the side in the −x direction of the heating element set 45. Therefore, thecenter 45 c in the x direction of the heating element set 45 is arranged on the −x direction side with respect to thecenter 41 c in the x direction of thesubstrate 41. - As shown in
FIG. 3 , a straight line CL connecting the center pc of thepressure roller 30 p and the center hc of thefilm unit 30 h is defined. Thecenter 41 c in the x direction of thesubstrate 41 is arranged in the +x direction from the straight line CL. Thus, thesubstrate 41 extends in the +x direction of the nip N, so that the sheet S that has passed through the nip N is easily peeled off from thefilm unit 30 h. - The
center 45 c of the heating element set 45 in the x direction is disposed on the straight line CL. The heating element set 45 is contained entirely within the region of the nip N and is located at the center of the nip N. Thus, the heat distribution of the nip N becomes uniform, and the sheet S passing through the nip N is uniformly heated. - As shown in
FIG. 4 , the heating element set 45 and the wiring set 55 are formed on the surface of the insulatinglayer 43 in the +z direction. Aprotective layer 46 is formed of a glass material or the like so as to cover the heating element set 45 and the wiring set 55. Theprotective layer 46 improves the sliding property between theheater unit 40 and thecylindrical film 35. - As shown in
FIG. 3 , theheater unit 40 is disposed inside thecylindrical film 35. A lubricant (not shown) is applied to the inner peripheral surface of thecylindrical film 35. Theheater unit 40 is brought into contact with the inner peripheral surface of thecylindrical film 35 through the lubricant. When theheater unit 40 generates heat, the viscosity of the lubricant is lowered. Thus, the sliding property between theheater unit 40 and thecylindrical film 35 is secured. - The
heat conductor 49 is formed of a metal material having a high thermal conductivity, such as copper. The outer shape of theheat conductor 49 is equivalent to the outer shape of thesubstrate 41 of theheater unit 40. Theheat conductor 49 is disposed in contact with the surface of theheater unit 40 in the −z direction. - The
support member 36 is made of a resin material such as a liquid crystal polymer. Thesupport member 36 is disposed so as to cover the side in the −z direction of theheater unit 40 and the both sides in the x direction of theheater unit 40. Thesupport member 36 supports theheater unit 40 via aheat conductor 49. Rounded chamfering is formed at both end portions in the x direction of thesupport member 36. Thesupport member 36 supports the inner peripheral surface of thecylindrical film 35 at both end portions in the x direction of theheater unit 40. - When the sheet S passing through the fixing
unit 30 is heated, a temperature distribution is generated in theheater unit 40 in accordance with the size of the sheet S. When theheater unit 40 becomes locally high temperature, there is a possibility that the heat resistance temperature of thesupport member 36 made of a resin material exceeds the heat resistance temperature. Theheat conductor 49 averages the temperature distribution of theheater unit 40. As a result, heat resistance of thesupport member 36 is ensured. - The
stay 38 is formed of a steel sheet material or the like. A cross section perpendicular to the y direction of thestay 38 is formed in a U shape. Thestay 38 is mounted on the surface in the −z direction of thesupport member 36 so as to block the opening of the U shape by thesupport member 36. Thestay 38 extends in the y direction. Both end portions of thestay 38 in the y direction in the y direction are fixed to the housing of the image forming apparatus 1. As a result, thefilm unit 30 h is supported by the image forming apparatus 1. Thestay 38 improves the bending rigidity of thefilm unit 30 h. A flange (not shown) for restricting the movement of thecylindrical film 35 in the y direction is mounted in the vicinity of both end portions in the y direction of thestay 38. - The heater thermometer 62 is arranged in the −z direction of the
heater unit 40 with theheat conductor 49 interposed therebetween. For example, the heater thermometer is mounted on and supported by a surface in the −z direction of thesupport member 36. The temperature sensitive element of the heater thermometer 62 contacts theheat conductor 49 through a hole passing through thesupport member 36 in the z direction. The heater thermometer 62 measures the temperature of theheater unit 40 via theheat conductor 49. - The thermostat 68 is arranged similarly to the heater thermometer 62. The thermostat 68 is incorporated into an electrical circuit, which will be described later. When the temperature of the
heater unit 40 detected through theheat conductor 49 exceeds a predetermined temperature, the thermostat 68 cuts off the power supply to the heating element set 45. -
FIG. 6 is a top view of the heater thermometer and thermostat (i.e., viewed from the −z direction). InFIG. 6 , the description of the supportingmember 36 is omitted. The following description of the arrangement of the heater thermometer, thermostat and film thermometer is used to describe the arrangement of the respective temperature sensitive elements. - A plurality of heater thermometers 62 (62 a, 62 b) are arranged in the heating element set 45 side by side along the y direction. The plurality of heater thermometers 62 are disposed at the center of the heating element set 45 in the x direction. That is, when viewed from the z direction, the plurality of heater thermometers 62 and the heating element set 45 overlap at least partially. The plurality of thermostats 68 (68 a, 68 b) are also arranged in the same manner as the plurality of heater thermometers 62 described above.
- A plurality of heater thermometers 62 include a
central heater thermometer 62 a and anend heater thermometer 62 b. - The
central heater thermometer 62 a measures the temperature of thecentral heating element 45 a. Thecentral heater thermometer 62 a is positioned within thecentral heating element 45 a. That is, when viewed from the z direction, thecentral heater thermometer 62 a and thecentral heating element 45 a overlap each other. - The
end heater thermometer 62 b measures the temperature of the second end heating element 45b 2. As described above, the first end heating element 45 b 1 and the second end heating element 45b 2 are similarly controlled in heat generation. Therefore, the temperature of the first end heating element 45 b 1 and the temperature of the second end heating element 45b 2 are equal to each other. Theend heater thermometer 62 b is located within a range of second end heating element 45b 2. That is, theend heater thermometer 62 b and the second end heating element 45b 2 overlap each other when viewed from the direction z. - The plurality of thermostats 68 include a
central thermostat 68 a and anend thermostat 68 b. - The
central thermostat 68 a interrupts the energization of the heating element set 45 when the temperature of thecentral heating element 45 a exceeds the predetermined temperature. Thecentral thermostat 68 a is positioned within the range of thecentral heating element 45 a. That is, when viewed in the z direction, thecentral thermostat 68 a and thecentral heating element 45 a overlap each other. - The
end thermostat 68 b interrupts energization of the heating element set 45 when the temperature of the first end heating element 45 b 1 exceeds a predetermined temperature. As described above, the first end heating element 45 b 1 and the second end heating element 45b 2 are similarly controlled in heat generation. Therefore, the temperature of the first end heating element 45 b 1 and the temperature of the second end heating element 45b 2 are equal to each other. Theend thermostat 68 b is located within a range of the first end heating element 45 b 1. That is, when viewed from the z direction, theend thermostat 68 b and the first end heating element 45 b 1 overlap each other. - As described above, the
central heater thermometer 62 a and thecentral thermostat thermometer 68 a are disposed on thecentral heating element 45 a so as to measure the temperature of thecentral heating element 45 a. When the temperature of thecentral heating element 45 a exceeds the predetermined temperature, the power supply to the heating element set 45 is interrupted. On the other hand, theend heater thermometer 62 b and theend thermostat 68 b are disposed on the first end heating element 45 b 1 and the second end heating element 45b 2. As a result, the temperatures of the first end heating element 45 b 1 and the second end heating element 45b 2 are measured. When the temperature of the first end heating element 45 b 1 and the second end heating element 45b 2 exceeds a predetermined temperature, the power supply to the heating element set 45 is interrupted. - The plurality of heaters 62 and the plurality of thermostats 68 are alternately arranged along the y direction. As described above, the first end heating element 45 b 1 is arranged on the +y direction side of the
central heating element 45 a. Within the first end heating element 45 b 1, theend thermostat 68 b is disposed. Thecentral heater thermometer 62 a is arranged on the +y direction side with respect to the central of thecentral heating element 45 a. Thecentral thermostat 68 a is arranged on the −y direction side with respect to the central ofcentral heating element 45 a. As described above, the second end heating element 45b 2 is arranged on the −y direction side of thecentral heating element 45 a. Within the second end heating element 45b 2, theend heater thermometer 62 b is located. Thus, theend thermostat 68 b, thecentral heater thermometer 62 a, thecentral thermostat 68 a and theend heater thermometer 62 b are arranged in this order along the −y direction. - In general, thermostat 68 utilizes a bimetal curve deformation with temperature changes to connect and disconnect the electrical circuit. The thermostat is formed to be elongated in conformity to the shape of the bimetal. Terminals extend outward from both end portions in the longitudinal direction of the thermostat 68. Each terminal is connected to a connector of external wiring. Therefore, it is necessary to secure a space outside the thermostat 68 in the longitudinal direction. Since there is no space at both ends in the x direction of the fixing
unit 30, the longitudinal direction of the thermostat 68 is arranged along the y direction. In this case, when a plurality of thermostats 68 are arranged adjacent to each other in the y direction, it becomes difficult to secure a connection space of the external wiring. - As described above, the plurality of heaters 62 and the plurality of thermostats 68 are alternately arranged along the y direction. Thus, a heater thermometer 62 is disposed adjacent to each thermostat 68 in the y direction. Therefore, it is possible to secure a space for connecting external wiring to the thermostat 68. In addition, the degree of freedom in the layout in the y direction of the thermostat 68 and the heater thermometer 62 is increased. This allows the thermostat 68 and heater thermometer 62 to be positioned at an optimal position to control the temperature of the fixing
unit 30. Further, it is easy to separate the alternating current wiring connected to the plurality of thermostats 68 from the direct current wiring connected to the plurality of heater thermometers 62. As a result, noise in the electric circuit is suppressed. - As shown in
FIG. 3 , thefilm thermometer 64 is disposed inside thecylindrical film 35 and on the +x direction side of theheater unit 40. Thefilm thermometer 64 contacts the inner peripheral surface of thecylindrical film 35 to measure the temperature of thecylindrical film 35. -
FIG. 7 is an electric circuit diagram of the fixing unit according to one embodiment. InFIG. 7 , the bottom view of theheater unit 40 shown inFIG. 5 is located at the top ofFIG. 7 , and the plan view of thesubstrate 41 shown inFIG. 6 is arranged at the bottom ofFIG. 7 .FIG. 7 also shows a plurality offilm thermometers 64 along with a cross section of thecylindrical film 35. The plurality offilm thermometers 64 includes acentral film thermometer 64 a and anend film thermometer 64 b. - The
central film thermometer 64 a comes into contact with the central portion of thecylindrical film 35 in the y direction. Thecentral film thermometer 64 a contacts thecylindrical film 35 within the range in the y-direction of thecentral heating element 45 a. Thecentral film thermometer 64 a measures the temperature of the central portion in the y direction of thecylindrical film 35. - The
end film thermometer 64 b contacts the end ofcylindrical film 35 in the −y direction. Theend film thermometer 64 b contacts thecylindrical film 35 within the range in the y-direction of the second end heating element 45b 2. Theend film thermometer 64 b measures the temperature at the end of thecylindrical film 35 in the −y direction. As described above, the first end heating element 45 b 1 and the second end heating element 45b 2 are similarly controlled in heat generation. Therefore, the temperature at the end portion in the −y direction of thecylindrical film 35 and the temperature at the end portion in the +y direction are identical. - A
power supply 95 is electrically connected to thecentral contact point 52 a via acentral triac 96 a. Thepower supply 95 is electrically connected to theend contact 52 b via anend triac 96 b. TheCPU 91 controls ON/OFF of thecentral triac 96 a and theend triac 96 b independently of each other. When theCPU 91 turns on thecentral triac 96 a, power is supplied to thecentral heating element 45 a from thepower supply 95. As a result, thecentral heating element 45 a generates heat. When theCPU 91 turns on theend triac 96 b, the power is supplied from thepower supply 95 to the first end heating element 45 b 1 and the second end heating element 45b 2. As a result, the first end heating element 45 b 1 and the second end heating element 45b 2 generate heat. As described above, thecentral heating element 45 a and the first end heating element 45 b 1 and the second end heating element 45b 2 are controlled in heat generation independently from each other. Thecentral heating element 45 a, the first end heating element 45 b 1 and the second end heating element 45b 2 are connected in parallel with respect to thepower supply 95. - The
power supply 95 is electrically connected to thecommon contact 58 via thecentral thermostat 68 a and theend thermostat 68 b. Thecentral thermostat 68 a and theend thermostat 68 b are connected in series. When the temperature of thecentral heating element 45 a rises abnormally, the detected temperature of thecentral thermostat 68 a exceeds the predetermined temperature. At this time, thecentral thermostat 68 a shuts off the power supply from thepower supply 95 to the heating element set 45. - When the temperature of the first end heating element 45 b 1 rises abnormally, the detected temperature of the
end thermostat 68 b exceeds a predetermined temperature. At this time, theend thermostat 68 b shuts off the power supply from thepower supply 95 to the heating element set 45. As described above, the first end heating element 45 b 1 and the second end heating element 45b 2 are similarly controlled in heat generation. Therefore, when the temperature of the second end heating element 45b 2 rises abnormally, the temperature of the first end heating element 45 b 1 also increases. Accordingly, in the case where the temperature of the second end heating element 45b 2 abnormally rises, theend thermostat 68 b also shuts off the power supplied from thepower supply 95 to the whole of heating element set 45. - The
CPU 91 of thecontroller 6 acquires the temperature of thecentral heating element 45 a from thecentral heater thermometer 62 a. TheCPU 91 acquires the temperature of the second end heating element 45b 2 from theend heater thermometer 62 b. The temperature of the second end heating element 45b 2 is equal to the temperature of the first end heating element 45 b 1. At the time of starting the fixingunit 30, theCPU 91 controls the heater thermometer 62 to measure the temperature of the heating element set 45. When the temperature of the heating element set 45 is lower than the predetermined temperature, theCPU 91 causes the heating element set 45 to generate heat only for a short time. Thereafter, theCPU 91 controls thepressure roller 30 p to start the rotation. The heat generated by the heating element set 45 lowers the viscosity of lubricant applied to the inner peripheral surface of thecylindrical film 35. Thus, the sliding property between theheater unit 40 and thecylindrical film 35 at the start of the rotation of thepressure roller 30 p is ensured. - The
CPU 91 controls thecentral film thermometer 64 a to measure the temperature of the central portion in the y direction of thecylindrical film 35. TheCPU 91 controls theend film thermometer 64 b to measure the temperature at the end portion in the −y direction of the cylindrical film. The temperature of the end of thecylindrical film 35 in the −y direction is equal to the temperature of the end of thecylindrical film 35 in the +y direction. The temperatures of the central portion and the end portion in the y direction of thecylindrical film 35 are measured during the operation of the fixingunit 30. TheCPU 91 controls the phase or wave number of electric power supplied to the heating element set 45 by thecentral triac 96 a and theend triac 96 b. TheCPU 91 controls the energization to thecentral heating element 45 a based on the temperature measurement result at the central portion in the y direction of thecylindrical film 35. TheCPU 91 controls the energization to the first end heating element 45 b 1 and the second end heating element 45b 2 based on the temperature measurement result at the end portion in the y direction of thecylindrical film 35. - As described above, the fixing
unit 30 of the embodiment includes thecylindrical film 35, the heating element set 45, the plurality of heater thermometers 62, and the plurality of thermostats 68. The heating element set 45 is disposed inside thecylindrical film 35, and the axial direction of thecylindrical film 35 is taken as the longitudinal direction of thecylindrical film 35. The plurality of heaters 62 and the plurality of thermostats 68 are alternately arranged along the longitudinal direction of the heating element set 45 within the heating element set 45. - The plurality of heaters 62 and the plurality of thermostats 68 are alternately arranged along the longitudinal direction of the
cylindrical film 35. Therefore, it is possible to secure a space for connecting external wiring to the thermostat 68 at both sides in the Y direction of thesubstrate 41. In addition, the degree of freedom in the layout on thesubstrate 41 in the y direction of the thermostat 68 and the heater thermometer 62 is increased. Thus, the thermostat 68 and the heater thermometer 62 are arranged at an optimal position to properly control the heating temperature. - The fixing
unit 30 has thesubstrate 41. Thesubstrate 41 is disposed inside thecylindrical film 35, and the axial direction of thecylindrical film 35 corresponds to the longitudinal direction of thesubstrate 41. The heating element set 45 is disposed on thesubstrate 41, and the short-side direction of thesubstrate 41 is defined as the short-side direction of the heating element set 45. The center in the lateral direction of the heating element set 45 is disposed at a position different from the center in the short-side direction of thesubstrate 41. In this case, a plurality of wirings can be arranged on one side in the lateral direction of the heating element set 45. As a result, heat generation of a plurality of heating elements included in the heating element set 45 can be controlled independently of each other. - The plurality of heaters 62 and the plurality of thermostats 68 are disposed at the center in the short-side direction of the heating element set 45. Thus, the plurality of heaters 62 and the plurality of thermostats 68 can accurately measure or detect the temperature of the heating element set 45.
- The heating element set 45 includes the
central heating element 45 a and the first end heating element 45 b 1 and the second end heating element 45b 2. Thecentral heating element 45 a is arranged at the center of thesubstrate 41 in the longitudinal direction. The first end heating element 45 b 1 and the second end heating element 45b 2 are disposed at both ends in the longitudinal direction of thesubstrate 41, and heat generation is controlled independently of thecentral heating element 45 a. The first end heating element 45 b 1 and the second end heating element 45b 2 are similarly controlled in heat generation. - When the sheet S having a small width in the y direction is heated, only the
central heating element 45 a is caused to generate heat. As a result, rise in the temperature at the end portion of thecylindrical film 35 in the y direction is suppressed. When the sheet S having a large width in the y direction is heated, the first end heating element 45 b 1 and the second end heating element 45b 2 are caused to generate heat in addition to thecentral heating element 45 a. At this time, the first end heating element 45 b 1 and the second end heating element 45b 2 generate heat in the same manner. Therefore, it is possible to uniformly heat the sheet S having a large width in the y-direction direction. As described above, the heating temperature can be appropriately controlled. - The plurality of heater thermometers 62 include the
central heater thermometer 62 a and theend heater thermometer 62 b. The plurality of thermostats 68 include thecentral thermostat 68 a and theend thermostat 68 b. Thecentral heater thermometer 62 a and thecentral thermostat 68 a are positioned within thecentral heating element 45 a. Theend thermostat 68 b is located within a range of the first end heating element 45 b 1. Theend heater thermometer 62 b is located within a range of the second end heating element 45b 2. - The
central heater thermometer 62 a measures the temperature of thecentral heating element 45 a. When the temperature of thecentral heating element 45 a measured by thecentral thermostat 68 a exceeds the predetermined temperature, the power supply to the heating element set 45 is interrupted. - As described above, the first end heating element 45 b 1 and the second end heating element 45
b 2 are similarly controlled in heat generation. Therefore, the temperature of the first end heating element 45 b 1 and the temperature of the second end heating element 45b 2 are equal to each other. Theend heater thermometer 62 b measures the temperature of the second end heating element 45b 2. When the temperature of the first end heating element 45b 2 exceeds the predetermined temperature by theend thermostat 68 b, the power supply to the heating element set 45 is interrupted. - As a result, the temperature of all heating elements included in the heating element set 45 is measured. When the temperature of any of the heating elements included in the heating element set 45 exceeds the predetermined temperature, the energization of the heating element set 45 is interrupted.
- Therefore, it is possible to appropriately control the heating temperature.
- The image forming apparatus 1 of the embodiment comprises the fixing
unit 30 as described above. The fixingunit 30 is capable of appropriately controlling the heating temperature. Accordingly, the image forming apparatus 1 can improve image quality. - The heating element set 45 of the aforementioned embodiments includes three heating elements (i.e., the
central heating element 45 a, the first end heating element 45 b 1, and the second end heating element 45 b 2). In contrast, the number of heating elements included in the heating element set 45 may be one or two or equal to or more than 4. The heater thermometer 62 of the aforementioned embodiments includes two heater thermometers (i.e., thecentral heater thermometer 62 a and theend heater thermometer 62 b). In contrast, the number of heater thermometers 62 may be equal to or more than 3. The plurality of thermostats 68 of the embodiment include two thermostats (i.e., thecentral thermostat 68 a and theend thermostat 68 b). In contrast, the number of the plurality of thermostats 68 may be equal to or more than three. - In the aforementioned embodiments, the image forming apparatus 1 and the fixing
unit 30 are described as examples of an image processing apparatus and a heating apparatus. Another example of the image processing apparatus is a decoloring apparatus having a decoloring unit. The decoloring apparatus performs a process of decoloring (i.e., erasing) an image formed on a sheet by a decolorable toner. The decoloring unit heats the decolorable toner image formed on the sheet passing through the nip to decolorize the toner image. - According to at least one embodiment as described above, the plurality of heaters 62 and the plurality of thermostats 68 are alternately arranged along the longitudinal direction of the heating element set 45. As a result, the heating temperature can be appropriately controlled.
- While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms, furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The embodiments and variations thereof are included within the scope and spirit of the invention, and are included within the scope of the appended claims and their equivalents.
Claims (20)
1. A fixing device which heats an image formed on a sheet to fix the image thereon, the fixing device comprising:
a cylindrical film supported in a rotatable manner and having an outer circumferential surface that comes into contact with the sheet; and
a heater unit provided in an inner space of the cylindrical film to heat an inner circumferential surface thereof and including:
a plurality of first heating elements disposed along a longitudinal direction of the cylindrical film, and
a first temperature sensor configured to measure a temperature of one of the plurality of first heating elements, wherein
the plurality of first heating elements and the first temperature sensor are connected in series by a first wiring.
2. The fixing device according to claim 1 , further comprising:
a controller configured to electrically connect or disconnect the first wiring and to which the temperature measured by the first temperature sensor is input, wherein
the controller disconnects the first wiring when the measured temperature is an abnormal temperature higher than a target temperature.
3. The fixing device according to claim 1 , wherein
the heater unit further includes:
a second heating element by which a central portion of the cylindrical film in the longitudinal direction is heated, and
a second temperature sensor configured to measure a temperature of one of the second heating element and the central portion,
the plurality of first heating elements is a pair of heating elements by which end portions of the cylindrical film in the longitudinal direction are heated, and
the second heating element is connected to the plurality of first heating elements in parallel by a second wiring.
4. The fixing device according to claim 1 , wherein
the heater unit further includes a second heating element by which a central portion of the cylindrical film in the longitudinal direction is heated, and
the plurality of first heating elements, the second heating element, and the first temperature sensor are connected in series by the first wiring.
5. The fixing device according to claim 1 , wherein the first temperature sensor is a thermostat.
6. An image forming apparatus comprising:
a transfer unit configured to transfer an image on a sheet; and
the fixing device according to claim 1 , which fixes the transferred image on the sheet.
7. A fixing device which heats an image formed on a sheet to fix the image thereon, the fixing device comprising:
a cylindrical film supported in a rotatable manner and having an outer circumferential surface that comes into contact with the sheet; and
a heater unit provided in an inner space of the cylindrical film to heat a heated area thereof and including:
a plurality of first heating elements disposed along a longitudinal direction of the cylindrical film, and
a first temperature sensor configured to measure a temperature of the heated area, wherein
the plurality of first heating elements and the first temperature sensor are connected in series by a first wiring.
8. The fixing device according to claim 7 , further comprising:
a controller configured to electrically connect or disconnect the first wiring and to which the temperature measured by the first temperature sensor is input, wherein
the controller disconnects the first wiring when the measured temperature is an abnormal temperature higher than a target temperature.
9. The fixing device according to claim 7 , wherein
the heater unit further includes:
a second heating element by which a central portion of the heated area in the longitudinal direction is heated, and
a second temperature sensor configured to measure a temperature of the central portion of the heated area,
the plurality of first heating elements is a pair of heating elements by which end portions of the heated area in the longitudinal direction are heated,
the temperature measured by the first temperature sensor is a temperature of one of the end portions of the heated area, and
the second heating element is connected to the plurality of first heating elements in parallel by a second wiring.
10. The fixing device according to claim 7 , wherein
the heater unit further includes a second heating element by which a central portion of the heated area in the longitudinal direction is heated, and
the plurality of first heating elements, the second heating element, and the first temperature sensor are connected in series by the first wiring.
11. The fixing device according to claim 7 , wherein the first temperature sensor is a thermostat.
12. An image forming apparatus comprising:
a transfer unit configured to transfer an image on a sheet; and
the fixing device according to claim 7 , which fixes the transferred image on the sheet.
13. A fixing device which heats an image formed on a sheet to fix the image thereon, the fixing device comprising:
a cylindrical film supported in a rotatable manner and having an outer circumferential surface that comes into contact with the sheet; and
a heater unit provided in an inner space of the cylindrical film to heat a heated area thereof and a heat conductor, the heater unit including:
a plurality of first heating elements disposed along a longitudinal direction of the cylindrical film, and
a first temperature sensor configured to measure a temperature of the heat conductor, wherein
the plurality of first heating elements and the first temperature sensor are connected in series by a first wiring.
14. The fixing device according to claim 13 , wherein the heat conductor is between the first temperature sensor and the plurality of first heating elements.
15. The fixing device according to claim 14 , wherein the heater unit further includes a substrate including a first surface on which the plurality of first heating elements are disposed and a second surface on which the heat conductor is disposed.
16. The fixing device according to claim 13 , further comprising:
a controller configured to electrically connect or disconnect the first wiring and to which the temperature measured by the first temperature sensor is input, wherein
the controller disconnects the first wiring when the measured temperature is an abnormal temperature higher than a target temperature.
17. The fixing device according to claim 13 , wherein
the heater unit further includes:
a second heating element by which a central portion of the heated area in the longitudinal direction is heated, and
a second temperature sensor configured to measure a temperature of a part of the heat conductor corresponding to the central portion,
the plurality of first heating elements is a pair of heating elements by which end portions of the heated area in the longitudinal direction are heated,
the temperature measured by the first temperature sensor is a temperature of another part of the heat conductor corresponding to one of the end portions, and
the second heating element is connected to the plurality of first heating elements in parallel by a second wiring.
18. The fixing device according to claim 13 , wherein
the heater unit further includes a second heating element by which a central portion of the heated area in the longitudinal direction is heated, and
the plurality of first heating elements, the second heating element, and the first temperature sensor are connected in series by the first wiring.
19. The fixing device according to claim 13 , wherein the first temperature sensor is a thermostat.
20. An image forming apparatus comprising:
a transfer unit configured to transfer an image on a sheet; and
the fixing device according to claim 13 , which fixes the transferred image on the sheet.
Priority Applications (4)
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US17/562,867 US20220121144A1 (en) | 2019-02-08 | 2021-12-27 | Heating device with thermometers and thermostats alternately arranged on a heat conductor |
US17/944,154 US11714369B2 (en) | 2019-02-08 | 2022-09-13 | Heating device with thermometers and thermostats alternately arranged on a heat conductor |
US18/332,772 US11982959B2 (en) | 2019-02-08 | 2023-06-12 | Heating device with thermometers and thermostats alternately arranged on a heat conductor |
US18/592,305 US20240201621A1 (en) | 2019-02-08 | 2024-02-29 | Heating device with thermometers and thermostats alternately arranged on a heat conductor |
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JP2019021852A JP7232659B2 (en) | 2019-02-08 | 2019-02-08 | Heating device and image processing device |
US16/734,215 US11042109B2 (en) | 2019-02-08 | 2020-01-03 | Heating apparatus with thermometers and thermostats alternately arranged inside a cylindrical film |
US17/322,755 US11237505B2 (en) | 2019-02-08 | 2021-05-17 | Heating device with thermometers and thermostats alternately arranged on a heat conductor |
US17/562,867 US20220121144A1 (en) | 2019-02-08 | 2021-12-27 | Heating device with thermometers and thermostats alternately arranged on a heat conductor |
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US17/322,755 Continuation US11237505B2 (en) | 2019-02-08 | 2021-05-17 | Heating device with thermometers and thermostats alternately arranged on a heat conductor |
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US17/944,154 Continuation US11714369B2 (en) | 2019-02-08 | 2022-09-13 | Heating device with thermometers and thermostats alternately arranged on a heat conductor |
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US16/734,215 Active US11042109B2 (en) | 2019-02-08 | 2020-01-03 | Heating apparatus with thermometers and thermostats alternately arranged inside a cylindrical film |
US17/322,755 Active US11237505B2 (en) | 2019-02-08 | 2021-05-17 | Heating device with thermometers and thermostats alternately arranged on a heat conductor |
US17/562,867 Abandoned US20220121144A1 (en) | 2019-02-08 | 2021-12-27 | Heating device with thermometers and thermostats alternately arranged on a heat conductor |
US17/944,154 Active US11714369B2 (en) | 2019-02-08 | 2022-09-13 | Heating device with thermometers and thermostats alternately arranged on a heat conductor |
US18/332,772 Active US11982959B2 (en) | 2019-02-08 | 2023-06-12 | Heating device with thermometers and thermostats alternately arranged on a heat conductor |
US18/592,305 Pending US20240201621A1 (en) | 2019-02-08 | 2024-02-29 | Heating device with thermometers and thermostats alternately arranged on a heat conductor |
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US16/734,215 Active US11042109B2 (en) | 2019-02-08 | 2020-01-03 | Heating apparatus with thermometers and thermostats alternately arranged inside a cylindrical film |
US17/322,755 Active US11237505B2 (en) | 2019-02-08 | 2021-05-17 | Heating device with thermometers and thermostats alternately arranged on a heat conductor |
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US17/944,154 Active US11714369B2 (en) | 2019-02-08 | 2022-09-13 | Heating device with thermometers and thermostats alternately arranged on a heat conductor |
US18/332,772 Active US11982959B2 (en) | 2019-02-08 | 2023-06-12 | Heating device with thermometers and thermostats alternately arranged on a heat conductor |
US18/592,305 Pending US20240201621A1 (en) | 2019-02-08 | 2024-02-29 | Heating device with thermometers and thermostats alternately arranged on a heat conductor |
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JP7251635B2 (en) * | 2019-08-29 | 2023-04-04 | 京セラドキュメントソリューションズ株式会社 | Fixing device and image forming device |
US11620235B1 (en) * | 2021-10-04 | 2023-04-04 | International Business Machines Corporation | Validation of store coherence relative to page translation invalidation |
US11959039B2 (en) * | 2022-03-16 | 2024-04-16 | Ricoh Company, Ltd. | Heating device configured to limit a temperature rise of a lubricant, fixing device, and image forming apparatus |
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2020
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2021
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2022
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2023
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Patent Citations (1)
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US20170363995A1 (en) * | 2016-06-20 | 2017-12-21 | Kabushiki Kaisha Toshiba | Heater and heating apparatus |
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US20240201621A1 (en) | 2024-06-20 |
US20230016128A1 (en) | 2023-01-19 |
US20210286300A1 (en) | 2021-09-16 |
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CN111552160B (en) | 2024-09-20 |
JP7232659B2 (en) | 2023-03-03 |
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US20230333502A1 (en) | 2023-10-19 |
US11982959B2 (en) | 2024-05-14 |
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