Heater and image heating apparatus

Abstract

This disclosure relates to heaters and image heating devices. A heater for an image heating device includes a substrate having a first surface and a second surface; heating elements electrically connected to a first electrode group, both formed on the first surface; and temperature sensing elements electrically connected to a second electrode group, both formed on the second surface. A plurality of first feed terminals disposed in the image heating device are in contact with the first electrode group. A plurality of second feed terminals disposed in the image heating device are in contact with the second electrode group. The first electrode group and the second electrode group are deployed on the same side of the substrate at the midpoint in the longitudinal direction. In the longitudinal direction, the second electrode group is deployed closer to the midpoint than the first electrode group. The first electrode group and the second electrode group are deployed with a gap between them in the longitudinal direction.

Description

Technical Field

[0001] This disclosure relates to an image heating apparatus, such as a fixing unit installed in an electrophotographic image forming apparatus (e.g., a copier or printer), or a surface treatment apparatus that reheats a toner image fixed on a recording medium to alter the gloss and surface properties of the toner image. In particular, this disclosure relates to an image heating apparatus that heats a toner image via a cylindrical film. This disclosure also relates to a heater installed in the image heating apparatus. Background Technology

[0002] Japanese Patent Publication No. 2019-207379 describes a fixing device having a heater within the internal space of a cylindrical fixing film, and the heater comprising multiple independently controllable heating elements. Furthermore, the heater described in Japanese Patent Publication No. 2019-207379 has a heating element on one side of a heater substrate and a thermistor for temperature detection on the other side, ensuring insulation between the electrodes of the heating element and the electrodes of the thermistor.

[0003] Depending on the configuration, the electrodes for the heating elements and the thermistor electrodes need to meet basic insulation or reinforced insulation requirements. According to Japanese Patent Publication No. 2019-207379, the electrodes for feeding multiple heating elements and the electrodes for feeding multiple thermistors need to be separated from each other in the longitudinal direction of the heater substrate by a distance corresponding to the required insulation distance between them.

[0004] However, to further ensure the insulation distance between the electrodes used to feed multiple heating elements and the conductors connected to the electrodes used to feed multiple thermistors, insulation distance is required not only in the longitudinal direction of the heater substrate but also in the transverse direction of the heater. Furthermore, when the number of thermistors required is increased to more accurately detect the temperature of multiple heating elements, the number of interconnecting lines connected to the thermistors disposed on the heater substrate also increases. In this case, the heater substrate needs to be extended in the transverse direction to ensure the insulation distance of multiple interconnecting lines. With the extension of the heater substrate in the transverse direction, problems arise such as increased fuser size, defective images due to the fuser roller gap width increasing beyond what is necessary, and increased heater cost. Summary of the Invention

[0005] A technique is disclosed that avoids an increase in the lateral dimension of the heater substrate while ensuring an insulating distance between the electrodes used to feed multiple heating elements and each of the electrodes and conductors used to feed the thermistors.

[0006] According to one aspect of this disclosure, a heater for use in an image heating device includes a substrate, at least one heating element formed on a first surface of the substrate, a first electrode group formed on the first surface and electrically connected to the at least one heating element, wherein a plurality of first power supply terminals disposed in the image heating device are in contact with the first electrode group, at least one temperature sensing element formed on a second surface of the substrate opposite to the first surface, and a second electrode group formed on the second surface and electrically connected to the at least one temperature sensing element, wherein a plurality of second power supply terminals disposed in the image heating device are in contact with the second electrode group, wherein the first electrode group and the second electrode group are deployed on the same side of the midpoint in the longitudinal direction of the substrate, and the second electrode group is deployed closer to the midpoint in the longitudinal direction than the first electrode group, and wherein the first electrode group and the second electrode group are deployed with a gap between the first electrode group and the second electrode group in the longitudinal direction.

[0007] Other features of this disclosure will become clear from the following description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description

[0008] Figure 1 This is a cross-sectional view of the image forming apparatus.

[0009] Figure 2 This is a cross-sectional view of the fixing unit.

[0010] Figure 3A and Figure 3B The diagram shows the cross-sectional view and configuration of the heater and each layer according to the first embodiment.

[0011] Figure 4 This is a cross-sectional view of the heater based on the comparative example.

[0012] Figure 5 This is a driving circuit diagram including a fixing unit according to the first embodiment.

[0013] Figure 6 This is a top view of the end of the fixing unit according to the first embodiment.

[0014] Figure 7 This is a top view of the end of the fixing unit according to the second embodiment.

[0015] Figure 8A and Figure 8B This is a cross-sectional view of the heater according to the third embodiment.

[0016] Figure 9 This is a driving circuit diagram including a fixing unit according to the third embodiment.

[0017] Figure 10 This is a top view of the end of the fixing unit according to the third embodiment.

[0018] Figure 11 This is a side view of the assembly portion of the AC connector and heater according to the third embodiment.

[0019] Figure 12 An FPC pattern spaced apart from the AC electrode according to the third embodiment is illustrated. Detailed Implementation

[0020] First Embodiment

[0021] Embodiments of this disclosure are described below with reference to the accompanying drawings. It should be noted that the embodiments described below are merely examples, and the technical scope of this disclosure is not limited to these embodiments. Furthermore, not all features and combinations thereof described in the embodiments are necessarily essential to this disclosure.

[0022] Image forming apparatus

[0023] Figure 1 This is a schematic configuration diagram of the image forming apparatus 1 according to this embodiment. The image forming apparatus 1 is a laser printer using electrophotographic recording technology. When the image forming apparatus 1 receives a print signal from an external device, the scanner unit 6 emits a laser beam based on the received image information to expose the photosensitive member 8 included in the image forming processing unit 7. Therefore, an electrostatic latent image based on the laser beam is formed on the photosensitive member 8. Then, when toner is supplied, a toner image corresponding to the image information is formed on the photosensitive member 8. The sheet supply cassette 2 has recording media P (e.g., plain paper) stacked therein. The recording media P stacked in the sheet supply cassette 2 is fed sheet by sheet by pick-up roller 3 and conveyed toward alignment roller 5 by transfer roller 4. When the toner image on the photosensitive member 8 reaches the transfer position formed by the photosensitive member 8 and the transfer roller 9, the recording media P is conveyed from the alignment roller 5 to the transfer position. When the recording media P passes the transfer position, the toner image on the photosensitive member 8 is transferred onto the recording media P. Subsequently, the recording medium P is heated by the fixing unit 20, causing the toner image transferred onto the recording medium P to be fixed onto the recording medium P. The recording medium P with the toner image fixed thereon is discharged via the transfer roller 10 and the discharge roller 11 onto the output tray 12 deployed on the upper side of the image forming apparatus 1. The motor 13 drives the fixing device, for example. In addition, the control circuit 14 connected to the AC power supply 15 supplies power to the fixing unit 20 and other loads. The photosensitive element 8, the scanner unit 6, the image forming processing unit 7, and the transfer roller 9 constitute an image forming unit for forming an unfixed toner image on the recording medium P.

[0024] Fixing unit

[0025] Figure 2 This is a cross-sectional view of the fixing unit 20.

[0026] The fixing unit 20 includes a cylindrical film (fixing film having a cylindrical shape) 21, a heater 30 disposed within the internal space of the film 21, and a pressure roller (gap portion forming member) 22 that forms a fixing gap portion N via the film 21 and the heater 30. The film 21 is brought into contact with an unfixed toner image formed on the recording medium P. The pressure roller 22 has a core metal 23 made of a material such as iron or aluminum and an elastic layer 24 made of a material such as heat-resistant rubber. The heater 30 is held by a heater holder 25, which serves as a holding member made of heat-resistant resin. The heater holder 25 also has a guiding function for guiding the rotation of the film 21. A support 26 is a metal support for applying pressure from a spring (not shown) to the heater holder 25.

[0027] The support 26 receives pressure from a spring (not shown) and pushes the heater 30 toward the pressure roller 22 via the heater holder 25. The elastic layer 24 of the pressure roller 22 elastically deforms under the force from the heater 30, thus forming the fixing roller gap portion N. The film 21 enters a mode where it is held in the fixing roller gap portion N by the heater 30 and the pressure roller 22. When the pressure roller 22 rotates in the direction of arrow R1 via a gear train (not shown) driven by the motor 13, the film 21 held in the fixing roller gap portion N rotates passively in the direction of arrow R2. Arrow F indicates the transport direction of the recording medium P. Furthermore, the recording medium P carrying the unfixed toner image enters the fixing roller gap portion N, and is thus held and transported while being heated. In this way, the toner image is fixed (the unfixed toner image is fixed to the recording medium by the heat of the heater).

[0028] Heater configuration

[0029] The configuration of the heater 30 according to this embodiment is described below. Figure 3A This is a cross-sectional view of heater 30 taken at the midpoint of the longitudinal direction. Figure 3A Corresponding to Figure 2 An enlarged view of the heater 30 shown. Figure 3B This is a plan view illustrating the configuration of heater 30 in the longitudinal direction LD. Figure 3B The back surface layer 1 and back surface layer 2 shown are views of the heater back surface layer 33, which serves as the surface of the substrate 31 away from the pressure roller 22. Back surface layer 2 is a view of the heater back surface layer 33 with protective glass 37, and back surface layer 1 is a view of the heater back surface layer 33 without protective glass 37. Note that the heater back surface layer 33 is also referred to as the "first surface". Figure 3BThe sliding surface layer 1 and sliding surface layer 2 shown are views of the heater sliding surface layer 32, which serves as the surface of the substrate 31 adjacent to the pressure roller 22. Sliding surface layer 2 is a view of the heater sliding surface layer 32 with protective glass 38, and sliding surface layer 1 is a view of the heater sliding surface layer 32 without protective glass 38. Note that the heater sliding surface layer 32 is also referred to as the "second surface". Furthermore, arrow F indicates the transport direction of the recording medium P. Figure 3B In this diagram, the reference position for the transmission of the recording medium P is represented by X0, which coincides with the midpoint of the recording medium P in the width direction. Even when recording media P of different sizes are fed, the recording medium P is still transmitted such that the midpoint of the recording medium P in the width direction of the sheet coincides with the reference position X0.

[0030] As indicated by the sliding surface layer 1, the sliding surface layer 32 of the substrate 31 includes heating elements 34a and 34b, each extending in the longitudinal direction LD of the heater 30. Heating element 34a is positioned upstream of the recording medium P in the transport direction, and heating element 34b is positioned downstream. Conductors 39a to 39c are connected to the two ends of the two heating elements. One end of conductor 39a is connected to heating element electrode 35b, and the other end is connected to heating element 34a. One end of conductor 39b is connected to heating element 34a, and the other end is connected to heating element 34b. One end of conductor 39c is connected to heating element 34b, and the other end is connected to heating element electrode 35a. Therefore, the heater circuit is configured such that heating elements 34a and 34b are simultaneously heated by feeding power between heating element electrodes 35a and 35b. Insulating protective glass 38 is deployed on the two heating elements 34a and 34b to cover the heating elements 34a and 34b and the conductors 39a to 39c except for the heating element electrodes 35a and 35b, for insulation purposes. That is, as Figure 3B As indicated by the sliding surface layer 2 shown, only the heating element electrodes 35a and 35b are exposed. In this way, by covering the heating elements 34a and 34b and conductors 39a to 39c with insulating protective glass 38, an insulating distance from other components is ensured. The membrane 21 slides on the surface of the protective glass 38. The power supply terminals 41a and 41b of the AC connector 41, which are electrical contact members (described below), are brought into contact with the heating element electrodes 35a and 35b, thus forming a power supply circuit that supplies power from the AC power supply 15 to the heating elements 34a and 34b. Note that the power supply terminals 41a and 41b are also referred to as "first power supply terminals," the AC connector 41, which is an electrical contact member, is also referred to as "first connector," and the heating element electrodes 35a and 35b are collectively referred to as "first electrode group."

[0031] As indicated by the back surface layer 1, a thermistor T1 (temperature sensing element) T1 is provided on the heater back surface layer 33 of the substrate 31. The thermistor T1 is positioned approximately at the same location as the transmission reference position X0. Furthermore, the thermistor T1 is connected to thermistor electrodes 36a and 36b via conductors 40a and 40b, respectively. Because the thermistor T1 has a negative resistance temperature characteristic and a resistance value that changes with temperature, it functions to detect the temperature of the heater 30. An insulating protective glass 37 is disposed on the thermistor T1 to cover the thermistor T1 and the conductors 40a and 40b except for the thermistor electrodes 36a and 36b, for insulation purposes. That is, as indicated by the back surface layer 1. Figure 3B As indicated by the back surface layer 2 shown, only the thermistor electrodes 36a and 36b are exposed. In this way, by covering the thermistor T1 and conductors 40a and 40b with insulating protective glass 37, an insulating distance from other components is ensured. The DC connector 413, as an electrical contact component (described below), contacts the electrodes 36a and 36b and is connected to the control circuit 14 via the DC cable 414. The control circuit 14 detects the temperature sensed by the thermistor T1. The control circuit 14 controls the power supplied to each heating element so that the sensed temperature of the thermistor T1 is the same as the target temperature suitable for the fixing operation. Note that the terminals of the DC connector 413 can directly contact the electrodes 36a and 36b, or the terminals of the DC connector 413 can be directly bonded to the electrodes 36a and 36b using high-melting-point solder, welding, etc. Alternatively, a surface-mount substrate connector can be mounted on the electrodes 36a and 36b using high-melting-point solder and can be connected to a connector located at one end of the DC cable 414. Note that the thermistor T1 is also referred to as a "temperature sensing element," the DC cable 414 is also referred to as a "second feed terminal," the DC connector 413, which serves as an electrical contact component, is also referred to as a "second connector," and the thermistor electrodes 36a and 36b are collectively referred to as the "second electrode group." It should also be noted that the DC cable 414 may have a single feed terminal or may have multiple feed terminals.

[0032] Control circuit of fixing unit

[0033] Figure 5An example of a control circuit 14, according to this embodiment, supplies power from an AC power source 15 to a fixing unit 20. The control circuit 14 includes a power supply unit 401, a zero-crossing detection circuit unit 409, a power voltage generation unit 412, a relay 408, and a power control unit 410 (hereinafter referred to as an engine controller 410). The power supply unit 401 is connected to one end of the AC power source 15 and is connected to the fixing unit 20 via a connection terminal 411b in an AC connector 411. An ON1 signal output from the engine controller 410 causes current to flow through a phototriac coupler 405 via a transistor 407. Therefore, current flows through the gate of the phototriac switch 402, and the phototriac switch 402 is turned on. The zero-crossing detection circuit unit 409 and the power voltage generation unit 412 are both connected to the AC power source 15. Zero-crossing detection circuit unit 409 outputs a zero-crossing signal indicating the zero-crossing point of the commercial AC waveform to engine controller 410. Power supply voltage generation unit 412 generates the power supply voltage required for the operation performed by engine controller 410 and other components based on the commercial AC waveform. Based on the temperature information sent from temperature sensing element T1 inside fixing unit 20 via DC cable 414, engine controller 410 outputs an ON1 signal to control power supply unit 401, so that the detected temperature is a predetermined temperature.

[0034] Arrangement of heating element electrodes and thermistor electrodes

[0035] The following is for reference. Figure 6 The arrangement of heating element electrodes 35a and 35b and thermistor electrodes 36a and 36b is described. According to this embodiment, the heating element electrodes 35a and 35b and the thermistor electrodes 36a and 36b are disposed in the same region on one side of the midpoint in the longitudinal direction of the substrate 31. Furthermore, the thermistor electrodes 36a and 36b are positioned closer to the midpoint (transfer reference position X0) than the heating element electrodes 35a and 35b. Additionally, among the heating element electrodes 35a and 35b, a predetermined gap (gap D) is provided between the heating element electrode 35b closer to the thermistor electrodes and the thermistor electrodes 36a and 36b in the longitudinal direction of the heater 30. Gap D is provided to ensure the required insulation distance between the heating element electrodes 35a and 35b and the thermistor electrodes 36a and 36b. By adopting such an arrangement, when the substrate 31 is viewed from the thickness direction of the heater, it is not necessary to consider the insulation distance between the conductors 40a and 40b in the back surface layer 1 and the heating element electrodes 35a and 35b in the sliding surface layer 1 in the lateral direction of the substrate 31.

[0036] Figure 4A comparative example of this embodiment is illustrated, wherein the thermistor electrodes 36a and 36b are deployed at a position further away from the transfer reference position X0 of the heater 30 than the heating element electrodes 35a and 35b (the opposite positional relationship to that according to this embodiment). In this case, the insulation distance between the heating element electrodes 35a and 35b and the conductor 40a connected to the thermistor T1 in the back surface layer needs to be such that this insulation distance is the sum of the distance in the thickness direction of the heater 30 and the creepage distances D1 and D2 in the lateral direction of the heater substrate. In order to ensure the above-mentioned insulation distance via the distance in the thickness direction of the heater 30 and the creepage distances D1 and D2 in the lateral direction of the heater substrate, the length in the lateral direction of the substrate 31 needs to be increased. Furthermore, the portion of the heater back surface layer 33 other than the thermistor electrodes 36a and 36b is covered by protective glass 37. At this time, since the protective glass 37 is used to protect the back surface, a glass with low insulation performance is used. In contrast, the protective glass 38, serving as the sliding surface layer 32, is made of glass with high insulation properties to resist external noise, such as lightning surges that can interfere with AC lines. To avoid increasing the lateral length of the substrate 31 described above, the glass used for the protective glass 37 can be replaced with glass with high insulation properties for the protective glass 38. However, this would increase costs. By arranging the heating element electrodes 35a and 35b and the thermistor electrodes 36a and 36b as described in this embodiment, an increase in the lateral length of the substrate 31 can be prevented, while ensuring the insulation distance between the heating element electrodes, the thermistor electrodes, and the conductors.

[0037] Second Embodiment

[0038] According to the first embodiment, a configuration including a heater 30 with a thermistor T1 and preventing an increase in length in the lateral direction while ensuring an insulation distance has been described. According to this embodiment, a configuration including a heater 30 with a thermistor T1 and preventing an increase in the size of the heater 30 not only in the lateral direction but also in the thickness direction while ensuring an insulation distance has been achieved. Note that in the second embodiment, the same reference numerals are used for parts having the same configuration and function as those shown in the first embodiment, and the description of these parts is not repeated. The configuration of the heater 30 according to this embodiment is the same as that according to the first embodiment. Figure 3A and Figure 3B The configuration shown is the same. That is, the sliding surface layer 32 of the substrate 31 is provided with heating elements 34a and 34b and heating element electrodes 35a and 35b, and the back surface layer 33 of the substrate 31 is provided with a thermistor T1, conductors 40a and 40b, and thermistor electrodes 36a and 36b.

[0039] Configuration of electrical contact components and conductive components

[0040] First, the configuration according to the first embodiment is described, wherein the electrical contact member and the conductive member are connected to the heating element and the thermistor electrode to ensure that the control circuit 14 is energized.

[0041] Figure 6 Examples of electrical connections between them are shown. Figure 3A and Figure 3B The heater shown and Figure 5 The control circuit 14 shown is illustrated. Figure 11 As shown in (described later), the AC connector 411 includes resilient terminals 411a and 411b in a U-shaped heat-resistant mold to clamp the heater 30 from above and below in the U-shaped opening. Thus, the AC connector 411 is assembled to the heater 30. With this configuration, terminals 411a and 411b are fitted to and electrically connected to the heating element electrodes 35a and 35b.

[0042] Each of terminals 411a and 411b is connected to the control circuit 14 via an AC cable. Current for driving the heating elements 34a and 34b is supplied from the control circuit 14 to the AC connector 411. Thermistor electrodes 36a and 36b are connected to the control circuit 14 via a DC connector 413 and a DC cable 414. The DC cable 414 is held by a cable guide or similar device to ensure a necessary distance W so as not to contact the AC connector 411. The DC connector 413 is mounted at a heat-resistant distance from the end of the membrane 21.

[0043] The following is for reference. Figure 7 The description describes a configuration in which electrical contact members and conductive members, according to the second embodiment, are connected to heating element electrodes 35a and 35b and thermistor electrodes 36a and 36b to ensure the energization of the control circuit 14.

[0044] According to this embodiment, a flexible flat cable (FFC) 60 is used to connect the control circuit 14 to the thermistor electrodes 36a and 36b. The FFC 60 is a film-like flat cable with a thickness of approximately 0.3 mm, wherein multiple conductive patterns are formed in parallel at equal intervals (e.g., 1 mm intervals) in the film-like inner layer of an insulator.

[0045] As described above, the AC connector 411 has a configuration in which resilient terminals 411a and 411b are disposed in a U-shaped heat-resistant mold. The FFC 60, connected to the thermistor electrodes 36a and 36b, is deployed to extend along the longitudinal direction of the heater 30. The FFC 60 is electrically connected to the thermistor electrodes 36a and 36b using a high-melting-point solder, welding, or the like. Furthermore, the heater 30 and the FFC 60 are clamped by the U-shaped opening of the AC connector 411 to assemble the heater 30 and the FFC 60, and thus terminals 411a and 411b are connected to the heating element electrodes 35a and 35b, respectively, and the FFC 60 is secured by the AC connector 411. In this way, at least a portion of the FFC 60 is held by the substrate 31. Note that it is assumed that an insulating distance is ensured between the FFC 60 and the heating element electrodes 35a and 35b in the AC connector 411. The configuration of the other components is the same as in the first embodiment.

[0046] As described above, according to the first embodiment, the DC cable 414 serves as a cable for connecting the thermistor electrodes 36a and 36b to the control circuit 14. When using the DC cable 414, it passes through the outside of the AC connector 411 to avoid contact with it, such as... Figure 6 As shown in the diagram. For this reason, the heaters of the heater 30 and the fixing unit 20 have a dimension in the thickness direction that is as large as the dimension indicated by the distance W. Therefore, according to the second embodiment, as... Figure 7 As shown, FFC 60 serves as a harness connecting the thermistor electrodes 36a and 36b to the control circuit 14. According to the second embodiment, by assembling the heater 30 and FFC 60 into a configuration clamped by the U-shaped opening of the AC connector 411, there is no need to consider the increase in the thickness dimension of the heater in the fixing unit 20. As described above, the configuration according to this embodiment enables the prevention of an increase in the size of the heater 30 not only in the lateral direction but also in the thickness direction while ensuring an insulating distance.

[0047] Third Embodiment

[0048] According to the first and second embodiments, a configuration in which the heater 30 includes a thermistor T1 has been described. According to this embodiment, a configuration is described having a heater 30 including multiple thermistors and preventing an increase in the width of the heater in the lateral direction while ensuring an insulating distance between the heating element electrodes and the thermistor electrodes. Note that for parts having the same configuration and function as those shown in the first and second embodiments, the same reference numerals are used in the third embodiment, and the description of these parts will not be repeated.

[0049] Heater configuration

[0050] First refer to Figure 8A and Figure 8B The configuration of the heater 700 according to this embodiment will be described. Figure 8A It is basically in Figure 8B The diagram shows a transverse cross-sectional view of the heater 700 taken at the transmission reference position X0.

[0051] The back surface layer 1 of the heater 700 includes conductors 701 and 703 on the substrate 705.

[0052] Conductor 701 is divided into conductor 701a, deployed upstream in the transport direction of recording medium P, and conductor 701b, deployed downstream. Heater 700 is disposed between conductors 701 and 703. Heater 700 includes heating element 702, which is heated by electricity supplied via conductors 701 and 703. Heating element 702 is divided into heating element 702a, deployed upstream in the transport direction of recording medium P, and heating element 702b, deployed downstream.

[0053] Furthermore, electrodes E7-1 to E7-7 are configured to supply power to heating elements 702a and 702b. Additionally, in the back surface layer 2, insulating protective glass 708 covers the portion excluding electrodes E7-1 to E7-7.

[0054] Figure 8B This is a plan view of heater 700. The layers are described below. In the back surface layer 1, seven heating blocks HB1 to HB7, consisting of an assembly of one of the free conductors 701, conductor 703, heating element 702, and one of the electrodes E7-1 to E7-7, are arranged in the longitudinal direction of heater 700.

[0055] The insulating protective glass 708 in the back surface layer 2 is formed in the portion excluding electrodes E7-1 to E7-7 and electrodes E8 and E9, and electrical contacts (not shown) are connected from the back surface side of the heater 700 to electrodes E7-1 to E7-7 and electrodes E8 and E9. This configuration allows the heating blocks HB1 to HB7 to be independently powered and independently electrically controlled. By dividing the heating blocks HB into seven heating blocks HB1 to HB7 in this way, at least four sheet feed areas can be formed (see...). Figure 8BThe heat distribution in areas (AREAs) 1 to 4 is shown. According to this embodiment, area 1 is classified for A5 sheet, area 2 for B5 sheet, area 3 for A4 sheet, and area 4 for letter paper sheet. Then, heating blocks HB for power supply are selected according to the size of the recording medium P. Note that the number of areas and heating blocks HB is not limited to those in this embodiment. Furthermore, the heating elements 702a-1 to 702a-7 and 702b-1 to 702b-7 in the heating blocks are not limited to the configuration in this embodiment where the entire pattern is used as a heating element. For example, a strip pattern with gaps can be used. Note that by changing the percentage of power supplied to each heating block, five or more heat distributions can be formed.

[0056] Thermistors T1-1 to T1-7 and T2-2 to T2-6 are disposed on the sliding surface layer 1 to detect the temperature of the heating blocks HB of the heater 700. Since thermistors T1-1 to T1-7 are primarily used for temperature control of the heating blocks, they are positioned at the center of their respective heating blocks. Thermistors T2-2 to T2-6 are edge thermistors used to detect the temperature of the non-sheet feed area (edge ​​portion) when feeding a recording medium P with a width that does not match the width of regions 1 to 4. For this purpose, the edge thermistors are positioned away from the transport reference position X0 of each of the heating blocks HB2 to HB6, except for the smaller heating blocks HB1 and HB7 located at both ends. Thermistors T1-1 to T1-7 are respectively connected to conductors ET1-1 to ET1-7 for detecting the resistance value of the thermistors, and all thermistors T1-1 to T1-7 are connected to a common conductor EG9. Thermistors T2-2 to T2-6 are connected to conductors ET2-2 to ET2-6 respectively, and all thermistors T2-2 to T2-6 are connected to a common conductor EG10. As mentioned above, the width L of heater 700 tends to increase with the increase of the number of thermistors and the number of conductors.

[0057] The sliding surface layer 2 is provided with a surface protective layer 709 made of slidable glass. The surface protective layer 709 is provided on the portion of the heater 700 except for the two ends, because in the sliding surface layer 1, the end of each conductor is used as an electrode.

[0058] Control circuit of fixing unit

[0059] Figure 9 This is the control circuit 800 of the heater 700 according to this embodiment. The AC power supply 15 is a commercial AC power supply connected to the image forming apparatus 1. The power supply voltages Vcc1 and Vcc2 are DC voltages generated by an AC / DC converter (not shown) connected to the AC power supply 15.

[0060] AC power supply 15 is connected to heater 700 via relays 830 and 840 and three-terminal bidirectional SCR switches 841 to 847. The three-terminal bidirectional SCR switches 841 to 847 are turned on and off by control signals FUSER1 to FUSER7 from CPU 820, respectively. One or more drive circuits for the three-terminal bidirectional SCR switches 841 to 847 are not shown.

[0061] The following describes the temperature detection circuit for the thermistor. Conductors EG9 and EG10 are connected to ground potential. Voltage Vcc1 is supplied by a reference voltage. Figure 8A and Figure 8B The thermistors T1-1 to T1-7, thermistors T2-2 to T2-6, resistors 851 to 857, and resistors 862 to 866 are described as voltage dividers. The resulting voltages are detected by the CPU 820 as Th1-1 to Th1-7 and Th2-2 to Th2-6 signals. Then, using information preset in the CPU 820's internal memory, the voltages are converted into temperature, thus detecting the temperature of the heating element 702.

[0062] In the internal processing executed by CPU 820, the power to be supplied is calculated based on the set temperature and the detected temperatures of thermistors T1-1 to T1-7, using, for example, PI control. CPU 80 converts the calculated power into a phase angle (phase control) and wavenumber (wavenumber control) as corresponding control levels. Therefore, CPU 820 controls the triac switches 841 to 847 according to the zero-crossing timing of the AC power supply 15 detected by the zero-crossing circuit 821.

[0063] The relays 830 and 840, along with the protection circuit, are described below. Relays 830 and 840 serve as power shut-off units to cut off power to the heater 700 when the temperature of the heater 700 rises excessively due to a malfunction or other reasons.

[0064] The operation performed by relay 830 is described below. When CPU 820 switches the RLON signal to the "high" state, transistor 833 is turned on. Therefore, the power supply voltage Vcc2 energizes the secondary coil of relay 830, and the primary contact of relay 830 enters the ON (conducting) state. When CPU 820 switches the RLON signal to the "low" state, transistor 833 enters the OFF (off) state. Therefore, the current flowing from the power supply voltage Vcc2 to the secondary coil of relay 830 is interrupted, and the primary contact of relay 830 enters the OFF state. The same applies to the operation performed by relay 840.

[0065] The operation performed by the safety circuit using relays 830 and 840 is described below. When the temperature of any of the detected thermistors T1-1 to T1-7 exceeds a predetermined set value, the comparator unit 831 activates the latch unit 832, and the latch unit 832 sets the RLOFF1 signal low for latching. When the RLOFF1 signal is low, even if the CPU 820 switches the RLON signal high, the transistor 833 remains in the OFF state, allowing the relay 830 to remain in the OFF state (safety state). Similarly, for thermistors T2-2 to T2-6, if the detected temperature exceeds a predetermined set value, the comparator unit 837 activates the latch unit 836, and the latch unit 836 sets the RLOFF2 signal low for latching. As described above, when the temperature of the heater 700 rises excessively due to a malfunction or other reasons, relays 830 and 840 also function as power cut-off units for the heater 700.

[0066] The following describes the relationship between the driving configuration using triac switches 841 to 847 and the number of thermistors. Triac switch 841, which drives heating block HB1, is connected in series with triac switch 842, which drives the adjacent heating block HB2. When only triac switch 842 is driven, only heating block HB2 generates heat. When both triac switches 841 and 842 are driven, heating blocks HB1 and HB2 generate heat. In this configuration, control is executed such that only heating block HB1 does not generate heat. Furthermore, in this configuration, since the control over heat generation by heating block HB2 and the control over heat generation by both heating blocks HB1 and HB2 can be selected, control can be executed to select the heating area for each sheet size.

[0067] According to this embodiment, a safety circuit is provided to prevent the heater 700 from heating to an abnormal temperature when an abnormality occurs under the control of the heater 700 due to a malfunction of the CPU 820, etc. Furthermore, the safety circuit according to this embodiment is configured such that even if one component fails and the heater 700 is not working, the heater 700 can be protected by detecting the abnormality in the heater 700 and shutting off relays 830 and 840. For this purpose, for example, two thermistors T1-3 and T2-3, along with a comparison unit and a latching unit corresponding to each of the thermistors T1-3 and T2-3, are provided in the heating block HB3. In this way, safety can be ensured even if one of the thermistors T1-3 and T2-3 fails. Since each of the heating blocks HB2, HB4, HB5, and HB6 is also controlled by an independent drive configuration, the two thermistors are similarly configured. Note that the heating block HB1 can be protected by a single thermistor T1-1, because only the heating block HB1 will not generate abnormal heat unless an abnormality occurs, such as in… Figure 9 A fault such as a broken wire occurred at point P.

[0068] Since this also applies to heating block HB7, a description of heating block HB7 will not be given again. Note that because heating blocks HB1 and HB7 have narrow heating areas, a single thermistor is used both as an edge thermistor for detecting the temperature in the non-sheet feed area (edge ​​portion) and as a thermistor for temperature control.

[0069] In this way, for a configuration where the heating block HB1 is driven by a semiconductor device located downstream of the semiconductor device used to drive the heating block HB2, the heater 700 can be protected in the event of a single failure, even if the number of thermistors it has is less than that of the heating block HB2.

[0070] Configuration of electrical contact components and conductive components

[0071] refer to Figure 10 The configuration in which the electrical contact member and the conductive member according to this embodiment are connected to the heating element electrode and the thermistor electrode to energize the control circuit 800 is described.

[0072] According to this embodiment, similar to the first embodiment, the thermistor electrodes EG10 to EG9, which are the ends of conductors EG10 to EG9, are deployed closer to the center of heater 700 than heating element electrodes E7-1 and E8 to prevent an increase in the size of the heater in the lateral direction. Furthermore, similar to the second embodiment, a flexible flat printed circuit (FPC) 90 is used to connect the control circuit 800 to the thermistor electrodes EG9, ET1-1 to ET1-4, ET2-3, ET2-2, and EG10.

[0073] FPC is a flat, film-like cable with a thickness of approximately 0.3 mm, in which multiple conductive patterns are wired within a film-like insulating inner layer. In the FFC 60 described in the second embodiment, the conductive patterns are formed in parallel at equal intervals (0.5 mm or 1 mm intervals). In contrast, in FPC 90, conductive patterns can be formed at any interval and in any shape. For this purpose, the interval between conductive patterns is reduced to 0.3 mm. By using FPC 90, the interval between adjacent patterns can be reduced compared to the case where patterns are formed on a heater substrate or FFC 60.

[0074] In addition, the control circuit 800 is connected to the AC connector 411 to drive the heating elements 702a-1 and 702b-1. Terminal 411a of the AC connector 411 is connected to the heating element electrode E8, and terminal 411b of the AC connector 411 is connected to the heating element electrode E7-1.

[0075] Figure 11 This is observed from the direction of arrow E. Figure 10 A view of the heater 700 and FPC 90 in the AC connector 411 shown. According to this embodiment, as in the second embodiment, the AC connector 411 is assembled to clamp the heater 700 and FPC 90 using its U-shaped opening. With this configuration, terminals 411a and 411b are electrically connected to the heating element electrodes 35a and 35b, respectively, and the FPC 90 is secured by the AC connector 411. Note that, as... Figure 11 and Figure 12 As shown, between the conductive pattern in FPC 90 and each terminal in terminals 411a and 411b, a creepage distance D3, which is the sum of the distance of heater 700 in the thickness direction and the creepage distances D4 and D5 in the lateral direction of heater 700, is required as an insulation distance.

[0076] Figure 12 This is observed along the direction of arrow XII according to this embodiment. Figure 11 The image shows a view of the FPC 90 and terminals 411a and 411b. For simplicity, in... Figure 12The mold for AC connector 411 is not shown; only terminals 411a and 411b are shown. The conductive patterns in the thermistor electrodes EG9, ET1-1 to ET1-4, ET2-3, ET2-2 and EG10, the control circuit 800, and the FPC 90 are connected using high-melting-point solder, welding, etc. While the conductive patterns in the FPC 90 can be formed in any spacing and shape as described above, appropriate copper foil spacing and shape are required in the connection portion between the FPC (one end of the FPC) and the thermistor electrodes due to limitations in the connection technology. Furthermore, since the other end of the FPC is connected to the control circuit 800, it is desirable to use conductive patterns with, for example, equal spacing of 0.5 mm, so that this end can be connected to a common FFC connector.

[0077] The following describes the portion of the AC connector where terminals 411a and 411b intersect with the FPC 90. For example... Figure 11 As shown, the sum of distances D3 and D4 (D5) needs to be maintained between each terminal in terminals 411a and 411b of the AC connector 411 and each pattern in the FPC 90.

[0078] Sufficient creepage distance is easily ensured between each of the four patterns (FPC_ET1-2 to FPC_ET1-4, FPC_ET2-3) routed near the center in the lateral direction of the FPC 90 and each of the terminals 411a and 411b. In contrast, it is difficult to ensure sufficient distance to maintain insulation distance between each of the patterns (FPC_EG10, FPC_ET2-2, FPC_ET1-1, FPC_EG9) deployed at the ends in the lateral direction of the FPC 90 and each of the terminals 411a and 411b. Therefore, the conductive patterns FPC_EG10, FPC_ET2-2, FPC_ET1-1, and FPC_EG9 deployed at the ends in the lateral direction of the FPC 90 are offset towards the center of the FPC 90 in the lateral direction (as shown in the image). Figure 12 (The area BA shown is curved).

[0079] In this way, conductive patterns FPC_EG10, FPC_ET2-2, FPC_ET1-1, and FPC_EG9 can provide an insulation distance (creepage distance) D4 or D5 with terminals 411a or 411b. If an insulation distance D4 or D5 can be provided, then a configuration in which two conductive patterns (conductive patterns FPC_EG10 and FPC_EG9) at both ends, or a conductive pattern (conductive pattern FPC_EG10 or FPC_EG9) at one end, bends towards the center of FPC 90 in the lateral direction can be adopted. Alternatively, all conductive patterns in FPC 90 can be deployed at equal intervals in the lateral direction.

[0080] In the FFC 60 described in the second embodiment, the conductive patterns are deployed at equal intervals in the lateral direction. Therefore, to ensure insulation distances D4 and D5 with respect to the heating element electrodes 35a and 35b, the width of the FFC 60 and the heater substrate in the lateral direction needs to be increased. Furthermore, compared to the case where patterns are formed on the FPC 90, it is difficult to reduce the distance between adjacent patterns in the lateral direction when the conductive patterns are formed directly on the substrate 705. Therefore, according to this embodiment, by using the FPC 90 as described above, the distance between the conductive patterns can be reduced to ensure insulation distances D4 and D5 with respect to the terminals 411a and 411b. Therefore, compared to the case using the FFC 60, the width of the heater in the lateral direction can be reduced.

[0081] As described above, according to this embodiment, by using FPC 90, even when heater 30 includes multiple thermistors, the dimensional increase of heater 700 in the lateral direction can be prevented, while ensuring the insulation distances D4 and D5 with terminals 411a and 411b.

[0082] While this disclosure has been described with reference to exemplary embodiments, it should be understood that this disclosure is not limited to the disclosed exemplary embodiments. The scope of the appended claims should be given the broadest interpretation to cover all such modifications and equivalent structures and functions.

Claims

1. A heater for use in an image heating device, the heater comprising: substrate; A plurality of heating elements are formed on a first surface of a substrate, wherein the plurality of heating elements are arranged in the longitudinal direction of the substrate and can be controlled independently; A first electrode group is formed on a first surface and electrically connected to the plurality of heating elements, wherein a plurality of first feed terminals disposed in the image heating device are in contact with the contact area of ​​each first electrode belonging to the first electrode group; A plurality of temperature sensing elements are formed on a second surface of a substrate opposite to a first surface, wherein the plurality of temperature sensing elements are arranged in the longitudinal direction of the substrate and are arranged to correspond to the plurality of heating elements. as well as A second electrode group is formed on the second surface and electrically connected to the plurality of temperature sensing elements, wherein a plurality of second feed terminals disposed in the image heating device are in contact with the contact area of ​​each second electrode belonging to the second electrode group. The contact areas of at least a portion of the first electrode group and at least a portion of the second electrode group are deployed on the same side of the midpoint in the longitudinal direction of the substrate. The contact area of ​​at least a portion of the first electrode group deployed on the same side of the midpoint of the substrate includes a first contact area and a second contact area, wherein the second contact area is deployed closer to the midpoint of the substrate than the first contact area. In the longitudinal direction, at least a portion of the contact area of ​​the second electrode group is deployed closer to the center of the substrate than the first contact area. In the longitudinal direction, the second contact area is positioned closer to the center of the substrate than at least a portion of the contact area of ​​the second electrode group, and The contact areas of the first contact area and at least a portion of the second electrode group are arranged such that there is a gap between the contact areas of the first contact area and at least a portion of the contact areas of the second electrode group in the longitudinal direction.

2. An image heating apparatus for heating an image formed on a recording medium, the image heating apparatus comprising: A membrane with a columnar shape; Heaters deployed inside the membrane The heater mentioned above includes: substrate, A plurality of heating elements are formed on a first surface of a substrate, wherein the plurality of heating elements are arranged in the longitudinal direction of the substrate and are independently controllable. A first electrode group formed on the first surface and electrically connected to the plurality of heating elements. A plurality of temperature sensing elements are formed on a second surface of a substrate opposite to a first surface, wherein the plurality of temperature sensing elements are arranged in the longitudinal direction of the substrate and are arranged corresponding to the plurality of heating elements. A second electrode group is formed on the second surface and electrically connected to the plurality of temperature sensing elements; A roll gap forming member is configured to form a roll gap portion together with the heater via the membrane; A plurality of first feed terminals that are in contact with the contact area of ​​each first electrode belonging to the first electrode group; and Multiple second feed terminals that are in contact with the contact area of ​​each second electrode belonging to the second electrode group. The image formed on the recording medium is heated in the roll gap section, and simultaneously held and transported in the roll gap section. The contact areas of at least a portion of the first electrode group and at least a portion of the second electrode group are deployed on the same side of the midpoint in the longitudinal direction of the substrate. The contact area of ​​at least a portion of the first electrode group deployed on the same side of the midpoint of the substrate includes a first contact area and a second contact area, wherein the second contact area is deployed closer to the midpoint of the substrate than the first contact area. In the longitudinal direction, at least a portion of the contact area of ​​the second electrode group is deployed closer to the center of the substrate than the first contact area. In the longitudinal direction, the second contact area is positioned closer to the center of the substrate than at least a portion of the contact area of ​​the second electrode group, and The contact areas of the first contact area and at least a portion of the second electrode group are arranged such that there is a gap between the contact areas of the first contact area and at least a portion of the contact areas of the second electrode group in the longitudinal direction.

3. The image heating device according to claim 2, wherein the plurality of first power supply terminals are disposed in a first connector, the first connector being configured to clamp the substrate.

4. The image heating device according to claim 2, wherein the plurality of second power supply terminals are deployed in the second connector.

5. The image heating device according to claim 2, wherein the plurality of second power supply terminals are a plurality of conductive patterns deployed inside the insulation layer of the film-shaped flat cable.

6. The image heating device of claim 5, wherein the plurality of first power supply terminals are disposed in a first connector, the first connector being configured to clamp the substrate and the membrane flat cable.

7. The image heating apparatus according to claim 6, wherein among the plurality of conductive patterns, the conductive pattern closest to the end of the substrate in the lateral direction bends toward the midpoint of the substrate in the lateral direction.

Images