JP2013235769A - Heating body and image heating device having heating body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heating body that feeds heating resistors via a plurality of through holes formed in a substrate and that prevents burning of the through holes and a conduction failure associated therewith.SOLUTION: A heating body includes: conductive sections 12o and 12p that are electrically connected to a heating resistor 12c provided along a longitudinal direction of a long thin electrically-insulating substrate 12a; and feed electrodes 12f and 12h that face the respective conductive sections 12o and 12p through the substrate 12a in a thickness direction of the substrate 12a. The substrate 12a is provided with three or more through holes 12i, 12j, 12k, 12l, 12m, and 12n that connect the conductive sections 12o and 12p and the respective feed electrodes 12f and 12h electrically. Feed contacts 16b and 16f that are electrically connected to the respective feed electrodes 12f and 12h are disposed in respective regions surrounded by the three or more through holes 12i, 12j, 12k, 12l, 12m, and 12n.

Description

  The present invention relates to a heating body suitable for use as a ceramic heater used in a fixing device mounted on an image forming apparatus such as an electrophotographic copying machine or an electrophotographic printer, and an image heating apparatus including the same.

  Image forming apparatuses adopting an electrophotographic system have been increased in speed, function, and color, and various printers, copiers, and the like are on the market.

  An electrophotographic copying machine or printer is equipped with a fixing device that heats and fixes an unfixed toner image formed on a recording material on the recording material. One of the heating methods in the fixing device is a film heating method. With the film heating method, a ceramic heater is arranged on the inner surface of a cylindrical fixing film, and a fixing roller and a recording material are brought into close contact with each other by placing a pressure roller at a position opposite to the ceramic heater across the fixing film. In this method, heat from the ceramic heater is applied to the recording material. The fixing film is configured based on a heat-resistant resin or metal.

  The ceramic heater used in the film heating type fixing device includes a heating resistor made of an electric resistor on a ceramic heater substrate, an electrode for power feeding made of silver, an insulation made of glass for protecting the heating resistor, etc. Often composed of layers. In many cases, the power supply means to the ceramic heater is performed by bringing a connector having a power supply contact into pressure contact with an electrode on the heater substrate to form an electrical conduction path.

  In a ceramic heater, the heating resistor and the electrode are often formed on the same surface of the heater substrate, but the heater substrate is used for the purpose of reducing the cost and reducing the substrate width by using a general-purpose connector. May be formed on opposite sides of each other. In the ceramic heater having such a configuration, a configuration is used in which a through hole is formed in the heater substrate and a conduction path between the heating resistor and the electrode is formed.

  Patent Document 1 discloses a ceramic heater in which resistance heating elements having different heat generation regions are formed on both surfaces of a heater substrate, and power can be supplied from one surface using a through hole.

  When a small-size recording material is continuously printed at the same print interval as a large-size recording material with a printer equipped with a film heating type fixing device, the area where the recording material of the ceramic heater does not pass (non-sheet-passing area) is excessively increased. It is known to increase the temperature (temperature increase of the non-sheet passing portion).

  In the configuration of the ceramic heater of Patent Document 1, as a countermeasure against a problem called non-sheet passing portion temperature rise, heating resistors having different lengths are provided on both sides of the heater substrate, and each is used properly according to the paper size. Further, when the two heating resistors are formed on the same surface of the heater substrate, the width of each heating resistor and the distance for securing the insulation between the two heating resistors are increased. Although it is necessary to widen the width, it is possible to prevent the width of the substrate from being increased by allocating to the front and back surfaces of the substrate.

  By the way, in the ceramic heater that supplies power to the heating resistors on both sides of the heater substrate through the through holes as described above, it is necessary to pass a large current compared to a general integrated circuit device. Abnormal heat generation may cause burning and poor conduction.

  Patent Document 2 discloses a configuration in which a plurality of through holes are used when power is supplied to the heating resistors on both sides of the heater substrate via the through holes, thereby preventing conduction failures due to burning of the through holes. ing.

JP 2002-299014 A JP-A-4-185455

  As described above, in ceramic heaters that supply power to heating resistors via through-holes, it is required to prevent through-hole burning and consequent conduction failure, and power is supplied via multiple through-holes. Even in the case of performing the above, further improvement is demanded.

  An object of the present invention is to provide a heating element that feeds power to a heating resistor through a plurality of through-holes formed in a substrate. An object of the present invention is to provide an image heating apparatus including a body.

  In order to achieve the above object, a representative configuration of the heating body according to the present invention is a heating body that generates heat by connecting a power supply contact and energizing the heating body. A heating resistor provided along the longitudinal direction of the substrate on the first surface of the substrate and generating heat upon energization; a conductor provided on both ends of the heating resistor on the first surface of the substrate; and the substrate A power supply electrode portion formed on the second surface of the first electrode and having a region facing the conductor, and three or more through holes that electrically connect the conductor and the power supply electrode portion, respectively. The three or more through holes are disposed so as to surround the power supply contact connected to the power supply electrode portion.

  In order to achieve the above object, a typical configuration of an image heating apparatus according to the present invention includes a heating body, a cylindrical flexible member that moves while being in contact with the heating body, and the flexible member. A pressure member that forms a nip portion with the heating body, and a power supply contact that is electrically connected to the heating body, and sandwiches and conveys a recording material that carries an image at the nip portion. In the image heating apparatus for heating an image on a recording material, the heating body includes an elongated electrically insulating substrate and a first surface of the substrate that is provided along the longitudinal direction of the substrate and generates heat when energized. A heating resistor, a conductor provided on both ends of the heating resistor on the first surface of the substrate, a feeding electrode portion having a region facing the conductor on the second surface of the substrate, Three or more relays that electrically connect the conductor and the feeding electrode portion, respectively. It has a hole, and characterized by disposing the feeding contacts in a region surrounded by the three or more through holes of the feeding electrode portion.

  ADVANTAGE OF THE INVENTION According to this invention, the heating body which can prevent the burning of a through hole and the conduction defect accompanying it, and an image heating apparatus provided with the heating body can be provided.

Cross-sectional schematic diagram of fixing device The figure showing the structure of the heater which concerns on Example 1. FIG. The figure showing the positional relationship of a through hole and a feed contact when connecting a feed connector to the heater according to the first embodiment The figure showing the target temperature at the time of the evaluation test which concerns on Example 1 The figure showing the through-hole position on the feed electrode part of the heater of the comparative example which concerns on Example 1 The figure showing the structure of the heater which concerns on Example 2. FIG. The figure showing the structure of the heater which concerns on Example 3. The figure showing the positional relationship of a through hole and a feed contact when a feed connector is connected to the heater according to the fourth embodiment. The figure showing the through-hole position on the feed electrode part of the heater of the comparative example which concerns on Example 4 The figure showing the positional relationship of a through hole and a feed contact when a feed connector is connected to the heater according to the fifth embodiment. The figure showing the through-hole position on the feed electrode part of the heater of the comparative example which concerns on Example 5

[Example 1]
(1) Fixing device (image heating device)
The configuration of the fixing device will be described with reference to FIG. The fixing device is mounted on an image forming apparatus such as an electrophotographic copying machine or an electrophotographic printer, and the unfixed toner image formed on the recording material is nipped and conveyed on the recording material by the image forming unit of the image forming apparatus. Heat fixing. FIG. 1 is a cross-sectional schematic diagram of a fixing device as an image heating device provided with a heating body according to the present invention.

  In the following description, regarding the fixing device and the members constituting the fixing device, the longitudinal direction means a direction orthogonal to the recording material conveyance direction on the surface of the recording material. The short side direction is a direction parallel to the recording material conveyance direction on the surface of the recording material. The length is a dimension in the longitudinal direction. The width is a dimension in the short direction. Regarding the recording material, the width direction means a direction orthogonal to the recording material conveyance direction on the surface of the recording material. The width is a dimension in the width direction.

  The fixing device 1 shown in this embodiment includes a ceramic heater (hereinafter referred to as a heater) 12 as a heating body, a cylindrical fixing film 11 as a flexible member, and a pressure roller 13 as a pressure member. And a film guide 14 as a guide member. The heater 12, the fixing film 11, the pressure roller 13, and the film guide 14 are all members that are long in the longitudinal direction.

  The film guide 14 is formed, for example, in a substantially bowl shape with a heat-resistant resin such as PPS (polyphenylene sulfite) or LCP (liquid crystal polymer). The film guide 14 guides the rotation of the fixing film 11 with an arcuate surface on the outer side in the short direction of the film guide 14. The heater 12 is supported by a groove provided along the longitudinal direction of the film guide 14 at the center of the lower surface of the film guide 14 in the short direction. Then, the fixing film 11 is loosely fitted on the outer periphery of the film guide 14 that supports the heater 12, and both longitudinal ends of the film guide 14 are supported on the front and rear side plates (not shown) of the apparatus frame 1 of the fixing device. ing.

  The pressure roller 13 includes a round shaft-shaped cored bar 13a, an elastic layer 13b provided on an outer peripheral surface between shafts provided at both longitudinal ends of the cored bar 13a, and an outer peripheral surface of the elastic layer 13b. And a release layer 13c provided on the substrate. The material of the cored bar 13a is a metal material such as iron or aluminum. The material of the elastic layer 13b is silicone rubber. The material of the release layer 13c is a fluororesin such as PFA.

  The pressure roller 13 is disposed so as to face the heater 12 with the fixing film 11 interposed therebetween, and shafts at both ends in the longitudinal direction of the cored bar 13 a are provided with bearings (not shown) on the front and rear side plates of the apparatus frame 1. It is supported so that it can rotate through. The bearing is urged by a pressure spring (not shown) in a direction perpendicular to the generatrix direction of the fixing film 11 to press the pressure roller 13 to the heater 12 via the fixing film 11. As a result, the elastic layer 13b of the pressure roller 13 is elastically deformed toward the metal core 13a, and a fixing nip portion (hereinafter, referred to as a predetermined width) is formed between the outer peripheral surface (surface) of the pressure roller 13 and the outer peripheral surface (surface) of the fixing film 11. N) is formed.

  The thickness of the fixing film 11 is preferably about 20 μm or more and 1000 μm or less in order to ensure good thermal conductivity. As the fixing film 11, a cylindrical single layer film made of a material such as PTFE (polytetrafluoroethylene), PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether), PPS (polyphenylene sulfide) can be used.

  Alternatively, a composite film having a tubular base film made of PI, PAI, PEEK, PES or the like on the surface of a tubular base film such as PTFE, PFA, FEP or a tube provided as a release layer can be used. Here, PI is polyimide, PAI is polyamideimide, PEEK is polyetheretherketone, PES is polyethersulfone, and PTFE / PFA / FEP is a tetrafluoroethylene / hexafluoropropylene copolymer.

In this example, a fixing film 11 having a total thickness of 75 μm formed by forming a 15 μm PFA coating film on a PI having a diameter of 24 mm, a length of 240 mm, and a thickness of 60 μm was used. Further, the pressure roller 13 having a diameter of 25 mm, a length of 260 mm, and a pressure hardness of 50 ° (measured by Asker C-type hardness meter when loaded with 500 g) was used.

(2) Configuration of Heater (Heating Body) 12 The configuration of the heater 12 will be described with reference to FIG. 2A is a schematic configuration diagram of the heater 12 when the heater 12 is viewed from the nip portion N side, and FIG. 2B is a schematic configuration diagram of the heater 12 when the heater 12 is viewed from the side opposite to the nip portion N side. . (C) is a longitudinal cross-sectional structure schematic diagram of the longitudinal direction which passes through the through hole 12j and the through hole 12m of the heater 12. FIG. The scale in the thickness direction of the heater 12 shown in FIG. 2C is shown enlarged for convenience of explanation.

  The heater 12 has an elongated heater substrate (hereinafter referred to as a substrate) 12a that is electrically insulating.

  On the surface (second surface) on the nip portion N side of the substrate 12a, a heating resistor (second heating resistor) 12b that generates heat when energized is provided along the longitudinal direction of the substrate 12a. A first feeding electrode portion 12f that is electrically connected to one end portion of the heating resistor 12b in the longitudinal direction is provided inside one end portion of the substrate 12a in the longitudinal direction, and heat is generated inside the other end portion in the longitudinal direction of the substrate. A feeding electrode portion 12h that is not physically in contact with the other end portion in the longitudinal direction of the resistor 12b is provided. Furthermore, a feeding electrode portion 12g that is electrically connected to the heating resistor 12b is provided inside the other end portion in the longitudinal direction of the substrate 12a. The feeding electrode portion 12g is disposed on the inner side in the longitudinal direction of the substrate 12a than the feeding electrode portion 12h.

  The feeding electrode portion 12f is disposed so as to have a region facing a conductive portion 12o described later, and the feeding electrode portion 12h is disposed so as to have a region facing a conductive portion 12p described later.

  Further, an insulating surface protective layer 12d is provided on the surface of the substrate 12a to cover the connecting portion between the heating resistor 12b and the heating resistor 12b in the power supply electrode portions 12f and 12g.

  A heating resistor (first heating resistor) 12c that generates heat when energized is provided along the longitudinal direction of the substrate 12a on the back surface (first surface) opposite to the fixing nip portion N side of the substrate 12a. is there. The heating resistor 12c is formed so as to be shorter than the heating resistor 12b, and is disposed at the approximate center in the longitudinal direction of the substrate 12a. A conductor 12o that is electrically connected to one end in the longitudinal direction of the heating resistor 12c is provided inside one end in the longitudinal direction of the substrate 12a, and the heating resistor 12c is disposed inside the other end in the longitudinal direction of the substrate. A conductor 12p that is electrically connected to the other end in the longitudinal direction is provided.

  Of the conductors 12o and 12p provided at both ends of the heating resistor 12c, the conductor 12o is disposed so as to face the feeding electrode portion 12f through the substrate 12a in the thickness direction of the substrate 12a. The conductor 12p is disposed in the thickness direction of the substrate 12a so as to face the power supply electrode portion 12h via the substrate 12a.

  Further, an insulating surface protective layer 12e is provided on the back surface of the substrate 12a to cover the connecting portion between the heating resistor 12c and the heating resistors 12c in the conductors 12o and 12p.

  The power supply electrode portion 12f and the conductor 12o are electrically connected through three through holes 12i, 12j, and 12k that penetrate the substrate 12a in the thickness direction of the substrate 12a. The power supply electrode portion 12h and the conductor 12p are electrically connected by three through holes 12m, 12n, and 12p that penetrate the substrate 12a in the thickness direction of the substrate 12a. Therefore, the feeding electrode portion 12f is used as a common electrode for the two heating resistors 12b and 12c, and the feeding electrode portion 12h is used as a feeding electrode for feeding power to the heating resistor 12c from the surface of the substrate 12a.

  Power supply connectors 16a, 16e, and 16c (see FIG. 3) as power supply members are electrically connected to the power supply electrode portions 12f, 12h, and 12g, respectively. As a result, the power supply electrodes 16f, 12h, and 12g are energized from the power supply connectors 16a, 16e, and 16c, and the heating resistors 12b and 12c generate heat.

  As the material of the substrate 12a, ceramics such as alumina and aluminum nitride can be used. In this example, an alumina substrate having a width of 7 mm in the short side direction, a length of 280 mm, and a thickness of 1 mm was used.

As the material of the heating resistors 12b and 12c, an electric resistance material such as Ag / Pd, RuO ₂ , Ta ₂ N, graphite, SiC, LaCrO ₃ is applied by screen printing in a linear shape or a linear shape. it can. Here, Ag / Pd is silver palladium, RuO ₂ is ruthenium oxide, Ta ₂ N is tantalum nitride, SiC is silicon carbide, and LaCrO ₃ is lanthanum chromite.

  In this example, both the heating resistors 12b and 12c were formed by screen printing and kneaded with Ag / Pd, glass powder, and organic binder. The length s of the heating resistor 12c was set to 115 mm, and the resistance value was set to 30Ω. The length w of the heating resistor 12b was set to 230 mm, and the resistance value was set to 15Ω. The heating resistor 12c has a length corresponding to a small size recording material (recording paper) having a small recording material width. The heating resistor 12b has a length corresponding to a large size recording material (recording paper) having a recording material width larger than that of a small size recording material.

  The surface protective layers 12d and 12e are formed for the purpose of ensuring insulation between the heating resistors 12b and 12c and the surface of the heater 12, and in this embodiment, insulating glass is formed to 80 μm by screen printing.

  The conductive electrode portions 12f, 12g, and 12h and the conductors 12o and 12p can be formed by screen printing using a conductive paste mainly composed of silver (Ag), platinum (Pt), or the like. Alternatively, it can be formed by screen printing using a conductive paste mainly composed of gold (Au), silver platinum (Ag / Pt) alloy, silver palladium (Ag / Pd) alloy, or the like. In this example, silver was screen-printed for any energizing electrode portion and conductor. In addition, since the energizing electrode portions 12f, 12g, and 12h and the conductors 12o and 12p are provided for the purpose of supplying power to the heating resistors 12b and 12c, the electric resistance is sufficiently smaller than that of the heating resistors 12b and 12c. did.

  As a method for forming the through holes 12i, 12j, 12k, 12l, 12m, and 12n, through holes are formed in the substrate 12a by laser processing before the energizing electrode portions 12f and 12h are formed. A conductive path can be formed by providing a conductive paste mainly composed of silver (Ag), platinum (Pt), gold (Au) or the like inside the through hole. Alternatively, a conductive path can be formed by providing a conductive paste mainly composed of silver platinum (Ag / Pt) alloy, silver palladium (Ag / Pd) alloy, or the like inside the through hole. In the present embodiment, a through hole having a diameter of 0.3 mm is formed by laser processing, and a conductive path is provided between the conductive electrode portions 12f and 12h and the conductors 12o and 12p by providing a silver conductive paste therein. Formed.

(3) Heat Fixing Operation of Fixing Device As shown in FIG. 1, the fixing device of the present embodiment is pressed by rotating the cored bar 13a of the pressure roller 13 by the rotation drive of a motor (not shown). The roller 13 rotates in the direction indicated by the arrow b. The rotation of the pressure roller 13 is transmitted to the fixing film 11 at the nip portion N by the frictional force between the surface of the pressure roller 13 and the surface of the fixing film 11. As a result, the fixing film 11 rotates (moves) in the direction indicated by the arrow a following the rotation of the pressure roller 13 while the inner peripheral surface (inner surface) of the fixing film 11 is in contact with the surface protective layer 12 d of the heater 12. .

  When heat-fixing an unfixed toner image on a large-sized recording material, a current-carrying control unit (not shown) is energized to the energizing electrode portions 12f and 12g of the heater 12 via the power feeding connectors 16a and 16c. 12b generates heat. As a result, the heater 12 is rapidly heated to heat the fixing film 11. The temperature of the heater 12 is detected by a temperature detection element (temperature detection member) 15 such as a thermistor provided at a predetermined position on the surface protective layer 12e on the back side of the substrate 12a. The energization control unit controls the energization amount to the heater 12 so as to maintain the heater 12 at a predetermined fixing temperature (target temperature) based on an output signal from the temperature detection element 15.

  In a state where the motor is driven to rotate and the heater 12 is maintained at a predetermined fixing temperature, a large size recording material P carrying an unfixed toner image T is introduced into the nip portion N with the toner image carrying surface facing upward. . The recording material P is nipped between the surface of the fixing film 11 and the surface of the pressure roller 13 in the nip portion N and is conveyed (nipped and conveyed) in that state. In this conveying process, the toner image T on the recording material P is heated and melted by the heater 12 through the fixing film 11 and is heated and fixed on the recording material by being pressurized at the nip portion N. The recording material P on which the toner image T is heat-fixed is separated from the surface of the fixing film 11 and discharged from the nip portion N.

  When heat-fixing an unfixed toner image on a small-size recording material, a current-carrying control unit (not shown) is energized to the current-carrying electrode portions 12f and 12h of the heater 12 via power-feed connectors 16a and 16e. 12c generates heat. As a result, the heater 12 is rapidly heated to heat the fixing film 11. The temperature of the heater 12 is detected by the temperature detection element 15. The energization control unit controls the energization amount to the heater 12 so as to maintain the heater 12 at a predetermined fixing temperature based on an output signal from the temperature detection element 15.

  In a state where the motor is driven to rotate and the heater 12 is maintained at a predetermined fixing temperature, a small size recording material P carrying an unfixed toner image T is introduced into the nip portion N with the toner image carrying surface facing upward. . The recording material P is nipped between the surface of the fixing film 11 and the surface of the pressure roller 13 in the nip portion N and is conveyed (nipped and conveyed) in that state. In this conveying process, the toner image T on the recording material P is heated and melted by the heater 12 through the fixing film 11 and is heated and fixed on the recording material by being pressurized at the nip portion N. The recording material P on which the toner image T is heat-fixed is separated from the surface of the fixing film 11 and discharged from the nip portion N.

(4) Positional relationship between the heater through-hole and the power supply contact of the power supply connector In the heater 12 of this embodiment, when the power supply contact is mounted, the region connecting the center points of the three through holes is the power supply contact. Each through hole was formed so as to surround it. The aim is to suppress the deterioration of the through holes by reducing the bias of the amount of current flowing to each through hole. The configuration shown in this embodiment can reduce the variation in the distance between the power supply contact and the through-hole and reduce the deviation in the amount of flowing current than when the power supply contact is arranged outside the region surrounded by the through-hole. To be connected.

  The positional relationship between the through hole and the power supply contact in this embodiment will be described with reference to FIG. FIG. 3 is a diagram showing the positional relationship between the through hole and the power supply contact when the power supply connectors 16a, 16c, and 16e are connected to the heater 12. FIG.

  3A is a diagram showing the positional relationship between the through holes 12i, 12j, 12k, 12l, 12m, and 12n and the power supply contacts 16b, 16d, and 16f when viewed from the downstream side in the recording material conveyance direction. (B) is a diagram showing the positional relationship between the through holes 12i, 12j, 12k, 12l, 12m, and 12n and the power supply contacts 16b, 16d, and 16f when viewed from the fixing nip N side.

  In the figure, (C) is a diagram showing the positional relationship between the through holes 12i, 12j, 12k and the feed contact 16b when viewed from the feed electrode portion 12f side. (D) is a view showing the positional relationship between the through holes 12i, 12j, 12k and the power supply contact 16b in the power supply electrode portion 12f when viewed from the nip N side. (E) is a diagram showing the positional relationship between the through holes 121, 12m, 12n and the power supply contact 16f in the power supply electrode portion 12h when viewed from the nip N side. The scales in the thickness direction of the heater 12 shown in FIGS. 3A and 3C are enlarged for the sake of explanation.

  With reference to FIGS. 3A to 3E, the positional relationship between the power supply contact and the through hole will be described.

  The power supply connectors 16a, 16c, and 16e are formed with power supply contacts 16b, 16d, and 16f, respectively, which are in electrical contact with the power supply electrode portions 12f, 12g, and 12h on the heater 12 to form electrical continuity. In this embodiment, the power supply connectors 16a, 16c, and 16e are inserted into the heater 12 supported by the film guide 14 from the right direction in FIG. 3B, that is, from the upstream side in the recording material conveyance direction. The film guide 14 is used for positioning and prevention of removal. As a result, the positions of the power supply contacts 16b, 16d, and 16f with respect to the power supply electrode portions 12f, 12g, and 12h on the heater 12 can be determined. With such a configuration, the positional relationship between the power supply contacts 16b and 16f and the respective through holes 12i, 12j, 12k, 12l, 12m, and 12n was determined.

  As shown in FIG. 3D, when a region formed by connecting the center points of the through holes 12i, 12j, and 12k is defined as t1, the power supply contact 16b is arranged so as to be included in the region of t1. Similarly, as shown in FIG. 3E, when a region formed by connecting the center points of the through holes 12l, 12m, and 12n is defined as t2, the power supply contact 16f is arranged so as to be included in the region of t2. did.

  Next, in order to confirm the effect of using the above configuration, the reliability of energization of the heater 12 was tested. As a test method, the heater 12 was incorporated in the fixing device 1 and connected to a 100 V power source and an energization control unit. Then, based on the detection result of the temperature detection element 15, the temperature was adjusted as shown in FIG. 4 for one cycle of 60 seconds, and the test was performed under the condition that repeated de-energization. Reliability was evaluated by the number of test cycles when the resistance of the through hole was increased and conduction was deteriorated.

  In addition, as a comparative example, a heater in which the positional relationship between the through holes 12i, 12j, and 12k and the power supply contact 16b, and the through holes 12l, 12m, and 12n and the power supply contact 16f is configured as shown in FIGS. The same test was conducted for. In the heater of the comparative example, the shape of the through holes 12i, 12j, 12k, 12l, 12m, and 12n and the distance between the through holes remain the same, and the positional relationship with the power supply contacts 16b and 16f is shifted to be the power supply contacts 16b and 16f. Is not included in the regions t1 and t2.

  In the heater 12 of this embodiment, the distance difference between the shortest and the longest distance between the power supply contact 16b and the center of each through hole in the energizing electrode portion 12f is 0.3 mm, and the heater of the comparative example In, it was set to 1.1 mm. In addition, the difference between the distance between the shortest and the longest distance between the feeding contact 16f and the center of each through hole in the energizing electrode portion 12h is 0.3 mm, and 1.1 mm in the heater of the comparative example. I tried to become.

  The respective evaluation results are shown in Table 1.

As shown in Table 1, the power supply contact 16b according to the configuration of the present embodiment is included in the region t1, and the power supply contact 16f is included in the region t2. The life is doubled. Therefore, the reliability of energization of the heater using the through hole of this example could be improved.

  In this evaluation, in the configuration in which both of the power supply contacts 16b and 16f shown in the comparative example are not included in the regions t1 and t2, the distance is long immediately after the through-hole having a short distance deteriorates first and the resistance increases. There was also a tendency for through holes to deteriorate due to current concentration. In contrast, in the configuration in which the power supply contact 16b, which is the configuration of the present embodiment, is included in the region t1, and the power supply contact 16f is included in the region t2, the current flows in a well-balanced manner, so that the number of times of deterioration can be increased. It was confirmed that the target effect was obtained. Therefore, the heater 12 of the present embodiment can prevent the through holes 12i, 12j, 12k, 12l, 12m, and 12n from being burned and the conduction failure associated therewith.

  This test is a mode in which the reliability of the heater is evaluated in an accelerated manner, and the continuity tends to decrease in the heater 12 of this embodiment. However, when the heater 12 of this embodiment is used in the fixing device of the image forming apparatus, the resistance is not increased due to the deterioration of the through holes 12i, 12j, 12k, 12l, 12m, and 12n in the same number of times. No problems in actual use were confirmed.

[Example 2]
Another example of the heater will be described. The heater 12 shown in FIGS. 2 and 3 of the first embodiment has a configuration in which heating resistors 12b and 12c are provided on both surfaces (front and back surfaces) of the substrate 12a for the purpose of preventing the temperature increase of the non-sheet passing portion of the small size paper. It was adopted. In contrast to this configuration, it will be described next that the same effects as those of the first embodiment can be obtained even when the heating resistor 12s is provided only on one surface (front surface or back surface) of the substrate 12a.

  FIG. 6 shows the configuration of the heater 12 when the heating resistor 12s is provided only on one surface of the substrate 12a, and the positional relationship between the through holes 12i, 12j, 12k, 12l, 12m, and 12n and the power supply contacts 16b and 16f. 6A is a schematic configuration diagram of the heater viewed from the front surface side of the substrate 12a, and FIG. 6B is a schematic configuration diagram of the heater viewed from the back surface side of the substrate 12a. (C) is the figure which expanded and showed the power feeding electrode part 12f part of (A), (D) is the figure which expanded and showed the power feeding electrode part 12h part of (A).

  In the case of the heater 12 having this configuration, the power supply electrode portion 12f is not used as a common electrode but is used as a power supply electrode that supplies power to the heating resistor 12s from the surface side of the substrate 12a. Further, the length x of the heating resistor 12s was set to 230 mm, which is a length corresponding to a large size recording material (recording paper) having a recording material width larger than that of the small size recording material, and the resistance value was set to 15Ω.

  The configuration of the heater 12 in this case includes a substrate 12a, power supply electrode portions 12f and 12h, a heating resistor 12s, conductors 12o and 12p, through holes 12i, 12j, 12k, 12l, 12m, and 12n, And a protective layer 12e.

  The heating resistor 12s is provided along the longitudinal direction of the substrate 12a on the back surface of the substrate 12a. The conductors 12o and 12p are provided at both ends of the heating resistor 12s on the back surface of the substrate 12a. The surface protective layer 12e is provided on the back surface of the substrate 12a, and covers the connecting portion between the heating resistor 12s and the heating resistors 12s in the conductors 12o and 12p. The power supply contact 16b is included in the region t1, and the power supply contact 16f is included in the region t2. As a result, it is possible to prevent the through holes 12i, 12j, 12k, 12l, 12m, and 12n from being burned and the conduction failure associated therewith.

  Further, even in a configuration in which the power supply contacts 16b and 16f are provided on the back surface of the substrate 12a due to the space at the time of connecting the power supply connectors 16a and 16e, the same operational effects as in the present embodiment can be obtained. That is, the heating resistor 12s and the conductors 12o and 12p are provided on the surface of the substrate 12a, the feeding electrode portions 12f and 12h are provided on the back surface of the substrate 12a, and the substrate 12a is sandwiched between the heating resistor 12s and the substrate 12a. The power is supplied from the back side. In the case of the heater 12 having this configuration, the surface of the substrate 12a is the first surface.

  In the heater 12 in this case as well, the feed contact 16b is included in the region t1 and the feed contact 16f is included in the region t2, so that the through holes 12i, 12j, 12k, 12l, 12m, and 12n are burned. The accompanying conduction failure can be prevented.

[Example 3]
Another example of the heater will be described. The heater 12 shown in FIGS. 2 and 3 has a configuration in which power supply electrode portions 12f and 12h having three through holes are provided inside both ends of the substrate 12a. Next, it will be described that similar effects can be obtained even when the positions of the power supply electrode portions 12f and 12h are changed.

  FIG. 7 shows the configuration of the heater 12 and the positional relationship between the through holes 12i, 12j, 12k, 12l, 12m, and 12n and the power supply contacts 16b and 16f when the power supply contacts 16b and 16f are collected on one end of the substrate 12a. 7A is a schematic configuration diagram of the heater viewed from the front surface side of the substrate 12a, and FIG. 7B is a schematic configuration diagram of the heater viewed from the back surface side of the substrate 12a. (C) is the figure which expanded and showed the power feeding electrode part 12f part of (A), (D) is the figure which expanded and showed the power feeding electrode part 12h part of (A).

  In the case of the heater 12 of the present embodiment, the feeding electrode portion 12f and the conductor 12o are provided at the end on the opposite side in the longitudinal direction of the substrate 12a from the configuration shown in FIG. Even in this case, the through-holes 12i, 12j, 12k, 12l, 12m, and 12n are burnt and the conduction failure is accompanied by the configuration in which the feeding contact 16b is included in the region t1 and the feeding contact 16f is included in the region t2. Can be prevented. That is, the effect of the heater 12 of this embodiment is not limited by the positions of the power supply contacts 16b and 16f.

[Example 4]
Another example of the heater will be described. The heater of the present embodiment aims to increase the reliability of energization by increasing the number of through holes per one feeding electrode portion. As shown in FIGS. 8A and 8B, the feeding electrode portion 12f and the conductor 12o are electrically connected by four through holes 12i, 12j, 12k, and 12q that penetrate the substrate 12a in the thickness direction of the substrate 12a. Connected to. Similarly, the feeding electrode portion 12h and the conductor 12p are electrically connected by four through holes 12l, 12m, 12n, and 12r that penetrate the substrate 12a in the thickness direction of the substrate 12a. Except for this point, the configuration is the same as the heater 12 of the first embodiment.

  FIG. 8 shows the configuration of the heater of this example and the positional relationship between the through hole and the power supply contact. 8A shows a positional relationship between the through holes 12i, 12j, 12k, 12q, 12l, 12m, 12n, and 12r and the power supply contacts 16b, 16d, and 16f when viewed from the downstream side in the recording material conveyance direction. It is. (B) is a diagram showing the positional relationship between the through holes 12i, 12j, 12k, 12q, 12l, 12m, 12n, and 12r and the power supply contacts 16b, 16d, and 16f when viewed from the nip N side.

  In the same figure, (C) is a diagram showing the positional relationship between the through holes 12i, 12j, 12k, 12q and the power supply contact 16b when viewed from the power supply electrode portion 12f side. (D) is a diagram showing the positional relationship between the through holes 12i, 12j, 12k, 12q and the power supply contact 16b in the power supply electrode portion 12f when viewed from the nip N side. (E) is a diagram showing the positional relationship between the through holes 121, 12m, 12n, and 12r and the power supply contact 16f in the power supply electrode portion 12h when viewed from the nip N side. The scale in the thickness direction of the heater 12 shown in (A) and (C) is enlarged for the sake of explanation.

  In the present embodiment, through holes 12q and 12r are added to the heater of the first embodiment. As shown in FIG. 8D, when a region formed by connecting the center points of the through holes 12i, 12j, 12k, and 12q is defined as t3, the power supply contact 16b is disposed so as to be included in the region of t3. . Similarly, as shown in FIG. 8E, if a region formed by connecting the center points of the through holes 12l, 12m, 12n, and 12r is defined as t4, the power supply contact 16f is included in the region of t4. Arranged.

  In order to confirm the effect of using the above configuration, the reliability of energization of the heater 12 was tested under the same conditions as in Example 1. Further, as a comparative example, as shown in FIGS. 9 (A) and 9 (B), the shape of the through holes and the distances between them remain the same, and the positional relationship with the power supply contacts 16b and 16f is shifted so that the power supply contacts 16b and 16f A heater having a configuration not included in the regions t3 and t4 was similarly tested.

  In the heater 12 of the present embodiment, the distance difference between the shortest and the longest distance between the power supply contact 16b and the center of each through hole in the power supply electrode portion 12f is 0.2 mm. . In the heater of the comparative example, it was set to 1.3 mm. Further, the distance between the shortest and the longest distance between the feed contact 16f and the center of each through hole in the electrode 12h is 0.2 mm, and 1.3 mm in the heater of the comparative example. I did it.

  The respective evaluation results are shown in Table 2.

As shown in Table 2, the configuration in which the power supply contact 16b according to the present embodiment is included in the region t3 and the power supply contact 16f is included in the region t4. The life is doubled. Therefore, the reliability of energization of the heater using the through hole of this example could be improved.

  In this evaluation, in the configuration in which the power supply contacts 16b and 16f shown in the comparative example are not included in the regions t3 and t4, the distance is long immediately after the through-hole having a short distance deteriorates first and the resistance increases. There was also a tendency for through holes to deteriorate due to current concentration. On the other hand, in the configuration in which the power supply contact 16b, which is the configuration of the present embodiment, is included in the region t3 and the power supply contact 16f is included in the region t4, the number of times of deterioration can be increased because the current flows in a well-balanced manner. It was confirmed that the target effect was obtained. Therefore, the heater 12 according to the present embodiment can prevent the through holes 12i, 12j, 12k, 12q, 12l, 12m, 12n, and 12r from being burned and the conduction failure associated therewith.

  This test is a mode in which the reliability of the heater is evaluated in an accelerated manner, and the continuity tends to decrease in the heater 12 of this embodiment. However, when the heater 12 of the present embodiment is used in the fixing device of the image forming apparatus, the increase in resistance due to the deterioration of the through holes 12i, 12j, 12k, 12q, 12l, 12m, 12n, 12r is the same number of times. It was not seen and the problem in practical use was not confirmed.

  In addition, compared with the heater 12 of Example 1, the heater 12 of this example can extend the number of tests by 400 times, and the effect of increasing the reliability by increasing the number of through holes was confirmed. . That is, in the first embodiment, the number of through holes is three, and in the present embodiment, the number of through holes is four. However, even in a configuration in which the number of through holes is further increased, the reliability of heater energization can be improved. Is easy to imagine.

  In the heater 12 of the present embodiment, similarly to the second embodiment, the heating resistor 12b is formed only on one surface of the substrate 12a, that is, even when the heating resistor 12b and the feeding electrode portion 12g are not provided. The effect of this can be obtained.

  The configuration of the heater 12 in this case includes a substrate 12a, power supply electrode portions 12f and 12h, a heating resistor 12c, conductors 12o and 12p, and through holes 12i, 12j, 12k, 12l, 12m, 12n, 12q, 12r. The power supply contact 16b is included in the region t3, and the power supply contact 16f is included in the region t4. Accordingly, it is possible to prevent the through holes 12i, 12j, 12k, 12l, 12m, 12n, 12q, and 12r from being burned and the accompanying conduction failure.

  In the heater 12 of the present embodiment, similar to the third embodiment, similar effects can be obtained even when the positions of the feeding electrode portions 12f and 12h are changed. Also in this case, the feed contact 16b is included in the region t3, and the feed contact 16f is included in the region t4, so that the through holes 12i, 12j, 12k, 12l, 12m, 12n, 12q, and 12r are burned. It is possible to prevent a conduction failure associated therewith.

[Example 5]
Another example of the heater will be described. The heater of the present embodiment has a configuration in which there are two power supply contacts each in contact with the electrodes 12f, 12g, and 12h. Except for this point, the configuration is the same as the heater 12 of the first embodiment.

  The configuration of the heater of this example and the positional relationship between the through hole and the power supply contact are shown in FIG. 10A shows the positional relationship between the through holes 12i, 12j, 12k, 12l, 12m, and 12n and the power supply contacts 16b, 16g, 16d, 16h, 16f, and 16i when viewed from the downstream side in the recording material conveyance direction. FIG. (B) is a diagram showing the positional relationship between the through holes 12i, 12j, 12k, 12l, 12m, and 12n and the power supply contacts 16b, 16g, 16d, 16h, 16f, and 16i when viewed from the nip N side.

  In the same figure, (C) is a diagram showing the positional relationship between the through holes 12i, 12j, 12k and the power supply contacts 16b, 16g when viewed from the power supply electrode portion 12f side. (D) is a diagram showing the positional relationship between the through holes 12i, 12j, 12k and the power supply contacts 16b, 16g in the power supply electrode portion 12f when viewed from the nip portion N side. (E) is a diagram showing the positional relationship between the through holes 121, 12m, and 12n and the power supply contacts 16f and 16i in the electrode 12h when viewed from the nip N side. The scales in the thickness direction of the heater 12 shown in FIGS. 10A and 10C are enlarged for the sake of explanation.

  In the heater 12 of the present embodiment, power supply contacts 16g, 16h, and 16i are added to the power supply connectors 16a, 16c, and 16e with respect to the configuration of the heater 12 of the first embodiment.

  As a result, the two feeding contacts (a plurality of feeding contacts) 16b and 16g of the feeding connector 16a are electrically connected to the feeding electrode portion 12f within the region of the feeding electrode portion 12f. On the other hand, the two feeding contacts (a plurality of feeding contacts) 16d and 16h of the feeding connector 16c are electrically connected to the feeding electrode portion 12g in the region of the feeding electrode portion 12g. Similarly, two power supply contacts (a plurality of power supply contacts) 16f and 16i of the power supply connector 16e are electrically connected to the power supply electrode portion 12h in the region of the power supply electrode portion 12h. This configuration increases the number of power supply contact points existing in one power supply electrode part, thereby improving the reliability of the conduction performance against variations in the contact state with the power supply electrode part for each power supply contact and the power supply performance. The purpose is that.

  In the two power supply electrode portions 12f and 12h where the through hole exists, the positional relationship between the through hole and the power supply contact is included in an area formed by connecting the two power supply contacts to the center point of the through hole. As shown in FIG. 10D, when a region formed by connecting the center points of the through holes 12i, 12j, and 12k is defined as t1, the power supply contacts 16b and 16g are arranged so as to be included in the region of t1. . Similarly, as shown in FIG. 10E, if a region formed by connecting the center points of the through holes 12l, 12m, and 12n is defined as t2, the power supply contacts 16f and i are included in the region of t2. Arranged.

  In order to confirm the effect of using the above configuration, the reliability of energization of the heater 12 was tested under the same conditions as in Example 1. In addition, as a comparative example, a heater in which the positional relationship between the through holes 12i, 12j, and 12k and the power supply contact 16b, and the through holes 12l, 12m, and 12n and the power supply contact 16f is configured as shown in FIGS. The same test was conducted for.

  In the heater of the comparative example, the shapes of the through holes 12i, 12j, 12k, 12l, 12m, and 12n and the intervals between the through holes remain the same. As shown in FIG. 11A, the positional relationship between the through holes 12i, 12j, and 12k and the power supply contacts 16b and 16g is shifted so that the power supply contacts 16b and 16g are not included in the region t1. Further, as shown in FIG. 11B, the positional relationship between the through holes 121, 12m, and 12n and the power supply contacts 16f and 16i is shifted so that the power supply contacts 16f and 16i are not included in the region t2.

  The respective evaluation results are shown in Table 3.

As shown in Table 3, the power supply contacts 16b and 16g according to the configuration of the present embodiment are included in the region t1, and the power supply contacts 16f and 16i are included in the region t2. 1.9 times longer life. Therefore, the reliability of energization of the heater using the through hole of this example could be improved.

  In this evaluation, the following tendency was observed in the configuration in which the power supply contacts 16b, 16g and 16f, 16i shown in the comparative example are not included in the regions t1 and t2. That is, immediately after the through hole with a short distance deteriorated and the resistance increased, the through hole with a long distance tended to deteriorate due to current concentration. On the other hand, in the configuration in which the power supply contacts 16b and 16g, which are the configuration of the present embodiment, are included in the region t1, and the power supply contacts 16f and 16i are included in the region t2, the number of times of deterioration is increased because current flows in a balanced manner. It was confirmed that the target effect was obtained. Therefore, the heater 12 according to the present embodiment can prevent the through holes 12i, 12j, 12k, 12l, 12m, and 12n from being burned and conduction failure associated therewith.

  This test is a mode in which the reliability of the heater is evaluated in an accelerated manner, and the continuity tends to decrease in the heater 12 of this embodiment. However, when the heater 12 of the present embodiment is used in the fixing device of the image forming apparatus, the increase in resistance due to the deterioration of the through holes 12i, 12j, 12k, 12l, 12m, and 12n is not observed in the same number of times. No problems in actual use were confirmed.

  In addition, compared with the heater 12 of Example 1, the heater 12 of this example can extend the number of tests by 150 times, and the effect of increasing the reliability can be confirmed by increasing the number of power supply contacts. . That is, in the first embodiment, the number of power supply contacts per one power supply electrode portion is one, and in this embodiment, the number of power supply contacts is two. However, even in a configuration in which the number of power supply contacts is increased, the reliability of energization of the heater is increased. You can easily imagine being done.

  In this embodiment, the number of through holes per power supply electrode portion is three and the number of power supply contacts is two. However, even in a configuration in which the number of through holes is further increased, it can be easily imagined that the reliability of energization of the heater can be improved by providing a plurality of power supply contact points per power supply electrode portion.

  Further, in this embodiment, the case where the two power supply contacts in one power supply electrode portion are all included in the region formed by the through hole and the case where all the power supply contacts are not included are compared. However, if one or more of the two power supply contacts are included in a region formed by a through hole, the configuration is the same as that of the first embodiment, and the same effect can be obtained. Therefore, in a configuration in which three or more through holes and three or more power supply contacts are provided, it is easy to improve the reliability of heater energization by providing one or more power supply contacts in the region formed by the through holes. I can imagine.

  In the heater 12 of the present embodiment, similarly to the second embodiment, the heating resistor 12b is formed only on one surface of the substrate 12a, that is, even when the heating resistor 12b and the feeding electrode portion 12g are not provided. The effect of this can be obtained.

  In this case, the heater 12 includes a substrate 12a, power supply electrode portions 12f and 12h, a heating resistor 12c, conductors 12o and 12p, and through holes 12i, 12j, 12k, 12l, 12m, and 12n. Have. The power supply contacts 16b and 16g are included in the region t1, and the power supply contacts 16f and 16i are included in the region t2. Thereby, it is possible to prevent the through holes 12i, 12j, 12k, 12l, 12m, and 12n from being burned and the conduction failure associated therewith.

  In the heater 12 of the present embodiment, similar to the third embodiment, similar effects can be obtained even when the positions of the feeding electrode portions 12f and 12h are changed. Even in this case, the feed contacts 16b and 16g are included in the region t1, and the feed contacts 16f and 16i are included in the region t2, so that the through holes 12i, 12j, 12k, 12l, 12m, and 12n are burned. It is possible to prevent a conduction failure associated therewith.

[Other embodiments]
The fixing devices according to the first to fourth embodiments are not limited to use as a device that heat-fixes an unfixed toner image t carried by the recording material P on the recording material. For example, it can also be used as an image heating apparatus that heats an unfixed toner image to be applied to a recording material, or an image heating apparatus that heats a toner image heated and fixed on a recording material to give glossiness to the surface of the toner image.

DESCRIPTION OF SYMBOLS 1 ... Fixing device, 11 ... Fixing film, 12 ... Heater, 12a ... Heater substrate, 12b, 12c, 12s ... Heating resistor, 12f, 12g, 12h ... Feed electrode part, 12i, 12j, 12k , 12l, 12m, 12n, 12q, 12r ... through hole, 12o, 12p ... conductor, 13 ... pressure roller, 16b, 16d, 16f, 16g, 16h, 16i ... feed contact, N ... fixing Nip, P ... Recording material, T ... Unfixed toner image, t1, t3 ... Area surrounded by through hole in power supply electrode part 12f, t2, t4 ... Surrounded by through hole in power supply electrode part 12h region

Claims (6)

In a heating element that generates heat by connecting a power supply contact and energizing it,
The heating body is
An elongated substrate having electrical insulation;
A heating resistor provided along the longitudinal direction of the substrate on the first surface of the substrate and generating heat by energization;
A conductor provided at both ends of the heating resistor on the first surface of the substrate;
A feeding electrode portion formed on the second surface of the substrate and having a region facing the conductor;
Three or more through-holes that electrically connect the conductor and the feeding electrode part, respectively,
The three or more through holes are disposed so as to surround the power supply contact connected to the power supply electrode portion. In a heating element that generates heat by connecting a power supply contact and energizing it,
The heating body is
An elongated substrate having electrical insulation;
A first heating resistor provided along the longitudinal direction of the substrate on the first surface of the substrate and generating heat by energization;
A conductor provided on both ends of the first heating resistor on the first surface of the substrate;
A second heating resistor provided along the longitudinal direction of the substrate on the second surface of the substrate and generating heat by energization;
A feeding electrode portion having a region facing the conductor on the first surface of the substrate;
Three or more through-holes that electrically connect the conductor and the feeding electrode part, respectively,
The three or more through holes are disposed so as to surround a power supply contact connected to the power supply electrode portion. A heating element;
A cylindrical flexible member that moves while in contact with the heating body;
A pressure member that forms a nip portion with the heating body via the flexible member;
A feeding contact electrically connected to the heating body;
An image heating apparatus that heats an image on a recording material while nipping and conveying a recording material carrying an image at the nip portion,
The heating body is
An elongated substrate having electrical insulation;
A heating resistor provided along the longitudinal direction of the substrate on the first surface of the substrate and generating heat by energization;
A conductor provided at both ends of the heating resistor on the first surface of the substrate;
A feeding electrode portion having a region facing the conductor on the second surface of the substrate;
Three or more through-holes that electrically connect the conductor and the feeding electrode part, respectively,
An image heating apparatus, wherein the power supply contact is disposed in a region surrounded by the three or more through holes of the power supply electrode portion. A heating element;
A cylindrical flexible member that moves while in contact with the heating body;
A pressure member that forms a nip portion with the heating body via the flexible member;
A feeding contact electrically connected to the heating body;
An image heating apparatus that heats an image on a recording material while nipping and conveying a recording material carrying an image at the nip portion,
The heating body is
An elongated substrate having electrical insulation;
A first heating resistor provided along the longitudinal direction of the substrate on the first surface of the substrate and generating heat by energization;
A conductor provided on both ends of the first heating resistor on the first surface of the substrate;
A second heating resistor provided along the longitudinal direction of the substrate on the second surface of the substrate and generating heat by energization;
A feeding electrode portion having a region facing the conductor on the second surface of the substrate;
Three or more through-holes that electrically connect the conductor and the feeding electrode part, respectively,
An image heating apparatus, wherein the power supply contact is disposed in a region surrounded by the three or more through holes of the power supply electrode portion.   The heating body according to claim 1, wherein there are a plurality of power supply contacts in contact with one of the power supply electrode portions.   5. The image heating apparatus according to claim 3, wherein there are a plurality of power supply contact points in contact with one of the power supply electrode portions.