JP2006267234A - Heating body and image heating apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce occurrence of poor contact in a contact member for supplying power an electrode part due to thermal expansion of a heating body. <P>SOLUTION: The heating body is provided with: a narrow long substrate 113; a heating resistor 114 provided along the longitudinal direction of the substrate; and electrode parts 112a and 112b connected to the heating resistor. The heating body used for an image heating apparatus heating an unfixed image on the material to be heated is provided with positioning members 117a and 117b to position the contact members supplying the power to the electrode parts, and the positioning members are moved together with the contact members, following the thermal expansion of the heating body in the longitudinal direction of the substrate. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a heating body used in an image heating apparatus that heats an unfixed image on a heated material, and an image heating apparatus including the heating body, and an image forming apparatus such as a copying machine, a printer, and a facsimile machine. It is suitable for use in.

  2. Description of the Related Art Conventionally, as a device for heating an unfixed toner image formed on a sheet as a material to be heated and fixing it on a sheet in an image forming apparatus such as a copying machine, a printer, a facsimile, etc., a contact heating type heat fixing device (hereinafter referred to as a heating type fixing device) Widely used are image heating devices and fixing devices).

  Particularly in recent years, from the viewpoint of energy saving, a film heating type heat fixing device having high heat conduction efficiency and a rapid rise in temperature has been widely used.

  An example of this film heating type heat fixing device is disclosed in Japanese Patent Application Laid-Open No. H10-228707. According to this heat fixing apparatus, a heater (heating body) is held on a heater support (holding member), and a thin film-like fixing film (flexible member) having heat resistance and flexibility is sandwiched between the heaters. A pressure nip (heating nip) is formed by pressure-contacting the pressure roller (pressure member). Then, a sheet carrying an unfixed toner image is introduced into the pressure nip, and the sheet is conveyed together with the fixing film, so that heat from the heater applied through the fixing film and pressure applied at the pressure nip An unfixed toner image is fixed on the sheet as a permanent image.

  In a heat-fixing device of the film heating system, usually, a heat-resistant, insulating, and heat-conductive ceramic substrate and a heating resistor as an energization heating part formed on the substrate by means of printing, baking, etc. are basically used. A ceramic heater having a low heat capacity and a high temperature rise is used as a whole, which generates heat by supplying power to the heating resistor.

  FIG. 9 is a plan view of a conventional ceramic heater as viewed from the surface side (resistance heating element) side. The ceramic heater 102 is a heater having a low heat capacity, which basically includes an elongated ceramic substrate 113 and a heating resistor 114 formed by printing and firing on the substrate surface in the longitudinal direction of the substrate 113. 112 a and 112 b are electrode patterns (electrode portions) formed on the surface portion of the longitudinal end portion of the substrate 113, and are electrically connected to the heating resistor 114. Therefore, the heating resistor 114 generates heat over the entire length when power is supplied between the electrode patterns 112a and 112b. The heater surface on which the heating resistor 114 is formed is covered with a withstand voltage coat 115 such as heat-resistant glass except for the electrode patterns 112a and 112b to protect the surface.

  FIG. 10 is a sectional view in the longitudinal direction of the heater substrate showing a state in which the heater 102 is held on the heater support 103. The heater support 103 formed to have a length longer than the longitudinal dimension of the heater 102 has a recess 103a on its lower surface, and the substrate 113 of the heater 102 is held in this recess with the heating resistor 203 facing downward. Yes.

  Connectors (contact members) 116a and 116b for supplying power between the electrode patterns 112a and 112b are attached to the heater support 103 holding the heater 102. FIG. 11 shows a state in which one of the connectors 116 a and 116 b is attached to the heater support 210. In the figure, reference numeral 104 denotes a fixing film, 105 denotes a flange member for restricting displacement of the fixing film 104, 106 denotes a pressure roller, and 107 denotes a pressure spring.

The connector 116a is inserted into the heater support 103 from one direction in the short side direction (width direction) of the heater 102, thereby making contact with the electrode pattern 112a (FIG. 10) and supplying power to the electrode pattern. At this time, by inserting the groove g1 provided in the connector 116a into the convex positioning portion 103b of the heater support 103, the connector 116a is positioned on the heater support 103 in a state of being in contact with the electrode pattern 112a. Similarly, by inserting the groove g2 provided in the connector 1116b into the convex positioning portion 103c of the heater support 103, the connector 116b is positioned on the heater support 103 in a state of being in contact with the electrode pattern 112b. (FIG. 10).
JP-A-4-204984

  However, in the above-described conventional heat fixing apparatus, since the connector is positioned by the heater support, the resistance heating element on the heater substrate generates heat, the heater expands thermally, and the length of the substrate relative to the heater support is increased. When extending in the direction, the heater electrode pattern and the contact portion of the connector positioned by the heater support may rub against each other, and the heater may cause a contact failure.

  Accordingly, an object of the present invention is to provide a heating body that can reduce the occurrence of contact failure with respect to a power supply contact member of an electrode portion due to thermal expansion of the heating body.

  Another object of the present invention is to provide an image heating apparatus including the heating body.

  A typical configuration of the heating body according to the present invention includes an elongated substrate, a heating resistor provided along the longitudinal direction of the substrate, and an electrode portion connected to the heating resistor. In the heating body used in an image heating apparatus for heating an unfixed image on a heated material, the substrate has a positioning member for positioning a contact member that supplies power to the electrode portion, and the positioning member is the contact A heating body that moves in the longitudinal direction of the substrate following the thermal expansion of the heating body together with a member.

  A typical configuration of the image heating apparatus according to the present invention includes a heating body having an elongated substrate, a heating resistor provided along a longitudinal direction of the substrate, and an electrode portion connected to the heating resistor. A contact member that supplies power to the electrode portion of the heating body, a flexible member that moves while contacting the heating body, and a pressure member that forms the nip portion with the heating body across the flexible member, In the image heating apparatus for heating an unfixed image on the heated material while nipping and conveying the heated material at the nip portion, the substrate of the heating body is a positioning member for positioning the contact member And the positioning member moves along the thermal expansion of the heating body together with the contact member in the longitudinal direction of the substrate.

  According to the present invention, since the positioning member moves in the longitudinal direction of the substrate when the heating body thermally expands, the contact member that supplies power to the electrode portion also moves together with the positioning member. Therefore, even when the heating body is thermally expanded, the electrode part and the contact part of the contact member are not rubbed, and a stable connection is possible between the electrode part and the contact member. The occurrence of contact failure can be reduced.

  Exemplary embodiments of the present invention will be described in detail below with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of the components described in this embodiment are not intended to limit the scope of the present invention only to those unless otherwise specified. Absent.

[Example of image forming apparatus]
An image forming apparatus including a heat fixing device as an image heating device according to the present invention will be described.

  FIG. 1 is an overall configuration diagram of an example of the image forming apparatus 120. The image forming apparatus of FIG. 1 is an electrophotographic process type laser printer.

  Reference numeral 121 denotes a scanner unit (exposure means), which has optical means and scanning means for irradiating and scanning laser light L based on image information.

  A process cartridge 122 includes a drum-shaped electrophotographic photosensitive member (hereinafter referred to as a photosensitive drum) 123 and process means acting on the drum. As process means, a charging roller (charging means) 122a for uniformly charging the circumferential surface of the photosensitive drum 123, and a developing roller (developing) for developing the electrostatic latent image formed on the circumferential surface of the photosensitive drum 123 with toner (developer). Means) 122b and a cleaner (cleaning means) 122c for removing the toner remaining on the circumferential surface of the photosensitive drum 123. The process cartridge 122 is detachably attached to an image forming apparatus main body (hereinafter referred to as an apparatus main body) 120A. The process cartridge 122 is attached / detached by opening the openable / closable cartridge cover 131 provided on the upper part of the apparatus main body 120A.

  The photosensitive drum 123 of the process cartridge 122 rotates in the clockwise direction indicated by the arrow, and the peripheral surface thereof is uniformly charged by the charging roller 122a. By irradiating the uniformly charged surface of the photosensitive drum 123 with laser light L from the scanner unit 121, an electrostatic latent image is formed on the peripheral surface of the photosensitive drum 123. The electrostatic latent image is supplied with toner by the developing roller 122b and is visualized as a toner image.

  On the other hand, recording sheets (hereinafter referred to as “sheets”) S to be heated stacked on the recording sheet stacking plate 124 are fed while being separated one by one by a feeding roller 125 and a separation pad 126. The fed sheet S is conveyed to the conveying roller 128 by the intermediate roller 127. The conveyance roller 128 conveys the sheet S to the transfer nip portion between the photosensitive drum 123 and the transfer roller 129 so as to be synchronized with the leading edge of the image formed on the circumferential surface of the photosensitive drum 123.

  The sheet S conveyed to the transfer nip portion is given a charge opposite in polarity to the toner from the transfer roller 129 from the back side, and the toner image formed on the photosensitive drum 123 is transferred to the sheet S.

  The sheet S to which the toner image is transferred is conveyed to the heat fixing device 101. The heat fixing device 101 applies heat and pressure to the unfixed toner image on the sheet S to fix it as a permanent image on the sheet.

  The sheet S exiting the heat fixing apparatus 101 is discharged onto a discharge tray 131 above the apparatus main body 120A by a discharge roller 130.

  Residual toner remaining on the peripheral surface of the photosensitive drum 123 after the toner image transfer without being transferred to the sheet S is removed by the cleaner 122c to prepare for the next image formation.

[Heat fixing device]
FIG. 2 is a configuration diagram of an example of a heat fixing device. FIG. 3 is an explanatory diagram of a heater and a power supply control system. FIG. 4 is an enlarged model view near the heating nip portion.

  The heat fixing device 101 is a pressure roller driving type film heat fixing device, which uses a cylindrical flexible and heat resistant fixing film 104 as a flexible member and uses the fixing film 104 as a pressure means. This is a device that is rotationally driven by the pressure roller 106. In the heat fixing apparatus of this embodiment, the same reference numerals are given to members and parts common to the conventional heat fixing apparatus.

  As shown in FIG. 3, the heater 102 as a heating element has a low heat capacity based on an elongated ceramic substrate 113 and a heating resistor 114 formed by printing and firing on the substrate surface in the longitudinal direction of the substrate 113. Ceramic heater. Electrode patterns (electrode portions) 112 a and 112 b formed on the surface portion of the longitudinal end portion of the substrate 113 are electrically connected to the heating resistor 114. When the connectors 116a and 116b as contact members are electrically connected to the electrode patterns 112a and 112b, respectively, and power is supplied between the electrode patterns, the heating resistor 114 generates heat over the entire length. The heater surface on which the heating resistor 114 is formed is covered with a withstand voltage coat 115 such as heat-resistant glass except for the electrode patterns 112a and 112b to protect the surface.

  Reference numeral 103 denotes a horizontally long heater support having a substantially semicircular cross section as a holding member, which also serves as a guide for the fixing film 104. Both longitudinal ends of the heater support 103 are supported by the apparatus frame 112. The heater 102 is supported at the center of the lower surface of the heater support 103 along the length of the support. That is, the heater support 103 has a recess 103a (FIG. 3) along the length of the support at the center of the lower surface, and the substrate 113 is attached to the recess 103a so that the heating resistor 114 faces downward. The heater 102 can be fixed to the heater support 3 by using a heat-resistant adhesive or the like, or using a connector or clip without bonding. In recent years, the latter method that does not use equipment for drying an adhesive is often employed.

  The fixing film 104 is a cylindrical thin film such as polyimide having excellent heat resistance, and is loosely fitted to a heater support 103 on which the heater 102 is fixedly supported.

  Reference numeral 105 denotes a flange member that receives the ends of the fixing film 104 disposed at both ends of the heater support 103 and restricts the displacement of the fixing film 104. The flange member 105 is disposed at both longitudinal ends of the heater support 103 and supported by the apparatus frame 112.

  Reference numeral 106 denotes an elastic pressure roller (hereinafter referred to as a pressure roller) as a pressure member. In the pressure roller 106, an elastic layer 106b such as silicon rubber is formed on the outer periphery of the cored bar 106a, and a tube such as PFA or PTFE having excellent releasability is covered as a release layer 106c on the outer side. The pressure roller 106 is rotatably supported at both ends of the metal core 106a on the apparatus frame 112 via bearings.

  Reference numeral 107 denotes a pressure spring as pressure means, which is disposed between the apparatus frame 112 and the flange member 105 at both longitudinal ends of the heater support 103. The pressure spring 107 pressurizes the flange member 105 to urge the heater support 103 to the elastic pressure roller 106. The lower surface of the heater 102 fixedly supported by the heater support 103 is pressed against each other with a predetermined contact pressure against roller elasticity with the fixing film 104 interposed therebetween. As a result, a heating nip portion N as a heating portion having a required width is formed between the fixing film 104 and the elastic pressure roller 106.

  Reference numeral 108 denotes a roller for nipping and conveying the heated sheet S, and 109 is an upper discharge guide for holding the roller 108 and guiding the upper side of the sheet.

  Reference numeral 110 denotes a discharge roller that forms a roller 108 and a discharge nip D. Reference numeral 111 denotes a discharge lower guide that guides the lower side of the sheet S on which the discharge roller 110 can be disposed. The upstream side of the discharge nip of the interval formed by the upper discharge guide 109 and the lower discharge guide 111 is configured to be gradually narrowed for easy and stable introduction into the discharge nip D.

  The pressure roller 106 is rotationally driven in the counterclockwise direction indicated by an arrow by a rotational driving system M as a driving means. A rotational force acts on the fixing film 104 by the pressure friction force in the heating nip N between the outer surface of the roller 106 and the outer surface of the fixing film 104 due to the rotation of the pressure roller 106. As a result, the fixing film 104 rotates following the outer periphery of the heater support 103 in the clockwise direction indicated by an arrow while the inner surface of the fixing film 104 contacts and slides on the lower surface of the heater 102. The heater support 103 also serves as a guide for the rotating fixing film 104.

[Explanation of heat fixing operation]
In normal use, power supply from the power supply circuit 142 (FIG. 2) to the heater 102 is started at the same time as the rotation of the fixing device (rotation drive of the pressure roller 106 and driven rotation of the fixing film 104 accompanying this). The heater 102 quickly rises in temperature, and the rotating fixing film 104 is heated by the generated heat. The temperature rise of the fixing film 104 is detected by a thermistor 142 as temperature detecting means that is in contact with the inner surface of the fixing film 104. The thermistor 142 outputs a temperature detection signal of the fixing film 104 to a control circuit 141 composed of an MPU or the like. The control circuit 141 controls the energization time of the electric power supplied to the heater 102 of the control circuit 140 based on the temperature detection signal from the thermistor 142 to adjust the temperature of the heater, that is, the temperature of the fixing film 104 to a predetermined temperature (target temperature). To do. In this temperature control state, the toner image surface of the sheet S on which the unfixed toner image T is formed and supported between the fixing film 104 and the pressure roller 106 in the heating nip portion N is passed through the inlet guide member 118 to the fixing film 104 side. (Fig. 4). The sheet S introduced into the heating nip portion N is nipped and conveyed through the fixing nip portion N, heated by the heat of the fixing film 104 in the nipping and conveying process, and pressed by the applied pressure of the heating nip portion N. The unfixed toner image T on S is fixed on the sheet S as a permanently fixed image. The sheet S that has passed through the heating nip N is separated from the surface of the fixing film 104 and conveyed, is nipped and conveyed by the rollers 108 and the discharge rollers 110, and is discharged through the discharge upper guide 109 and the discharge lower guide 111.

  In the heat fixing apparatus shown in the present embodiment, substantially no tension acts on the fixing film 104 except for the heating nip portion N in the rotation state of the fixing film 104 driven by the pressure roller 106. Therefore, the film moving force along the length of the heater support 103 along with the rotation of the fixing film 104 is small, and the flange member 105 as the film moving control means can be simplified. There are advantages such as being able to.

[Connection structure with heater connector]
FIG. 5 is a sectional view in the longitudinal direction of the heater substrate showing a state in which the heater is held on the heater support. FIGS. 6A and 6B are explanatory views showing a state where the positioning member is attached to the heater substrate, and FIG. 6C is an explanatory view showing a state where the positioning member is attached to the heater support. FIG. 7 is an explanatory view showing a state where the connector is attached to one of the positioning members provided in the heater. FIG. 8 is an explanatory diagram of the relationship between the heater extension amount and the positioning member movement amount due to the thermal expansion of the heater.

  As shown in FIG. 5, the heater 102 shown in this embodiment has positioning members 117 a and 117 b at both longitudinal ends of the back surface of the substrate 113. The positioning members 117a and 117b are fixed to the positions corresponding to the electrode patterns 112a and 112b on the back surface of the substrate 113 by the adhesive 118 (FIGS. 6A and 6B). Holes 119a and 119b (FIG. 5) of predetermined sizes are formed in the heater support 103 so that the positioning members 117a and 117b can be moved in the longitudinal direction of the substrate 113 of the heater 102. Thus, the holes 119a and 119b of the heater support 103 are formed larger in the longitudinal direction of the substrate 113 than the positioning members 117a and 117b of the heater 102, so that when the heater 102 is attached to the heater support 103, the positioning members 117a and 117a, A gap C can be provided between 117b and the holes 119a and 119b of the heater support 103 (FIG. 6C).

  Connectors 116a and 116b are connected to the positioning members 117a and 117b of the heater 102 attached to the heater support 103 as shown in FIG. The connectors 116a and 116b are in contact with the electrode patterns 112a and 112b (FIG. 5) by being inserted into the heater support 103 from one direction in the short direction (width direction) of the heater 102, so that power can be supplied to the electrode patterns. Become. At this time, by inserting the grooves g1 and g2 provided in the connectors 116a and 116b into the convex positioning portions p1 and p2 provided in the positioning members 117a and 117b, the connectors 116a and 116b are in contact with the electrode patterns 112a and 112b. In this state, the heater support 103 is positioned (FIG. 5).

  As shown in FIG. 8, when the substrate 113 extends in the longitudinal direction due to the thermal expansion of the heater 102, the positioning members 117 a and 117 b move along with the substrate 113 in the longitudinal direction of the substrate following the thermal expansion of the heater 102. As a result, the connectors 116a and 116b also move in the longitudinal direction of the substrate, so that the contact position relationship between the connectors 116a and 116b and the electrode patterns 112a and 112b does not change. Therefore, it is possible to prevent the occurrence of contact failure between the connectors 116a and 116b and the electrode patterns 112a and 112b.

  In this embodiment, another example of the heater 102 will be described.

  In the first embodiment, the heater 102 in which the positioning members 117a and 117b are fixed to the longitudinal end portion of the back surface of the substrate 113 with the adhesive 118 has been described. In this case, the substrate 113 and the positioning members 117a and 117b must be formed separately.

  Therefore, the positioning members 117a and 117b may be formed integrally with the substrate 113 using an appropriate processing technique such as press processing. In the heater 102 having such a configuration, the same operation and effect as the heater of the first embodiment can be obtained. Further, in the heater 102 of this embodiment, the fixing process of the positioning members 117a and 117b to the back surface of the substrate 113 can be simplified.

[Other]
The image heating apparatus according to the present invention is not limited to use as the heat fixing apparatus of the embodiment, but is an assumed fixing apparatus for temporarily fixing an unfixed image on a recording material, and an image surface such as a gloss by reheating a recording material carrying a fixed image. It is also effective as an image heating apparatus such as a surface modification apparatus for modifying the properties.

1 is an overall configuration diagram of an example of an image forming apparatus. 1 is a configuration diagram of an example of a heat fixing device. Explanatory drawing of a heater and an electric power feeding control system. The enlarged model figure near a heating nip part. Sectional drawing of the heater substrate longitudinal direction which shows the state hold | maintained on the heater support body. (A) And (b) is explanatory drawing which shows a mode that a positioning member is attached to the board | substrate of a heater, (c) is explanatory drawing which shows the state which attached the positioning member to the heater support body. Explanatory drawing which shows a mode that a connector is attached to the positioning member provided in the heater. Explanatory drawing of the relationship between the heater extension amount by the thermal expansion of a heater, and a positioning member movement amount. The top view of the conventional heater. Sectional drawing of the heater substrate longitudinal direction which shows the state hold | maintained the conventional heater on the heater support body. Explanatory drawing which shows a mode that a connector is attached to the heater support body which supported the conventional heater.

Explanation of symbols

101... Heating fixing device 102... Heater (heating element)
103 ··· Heater support 104 ··· Fixing film (heat resistant film)
106 ... Pressure rollers 112a, 112b ... Electrode portions 116a, 116b on the heater ... Connectors (contact members)
117 ... Positioning member 118 ... Adhesive 119 ... Heater support hole S ... Sheet T ... Toner N ... Heating nip

Claims (5)

An image having an elongated substrate, a heating resistor provided along the longitudinal direction of the substrate, and an electrode portion connected to the heating resistor, and heating an unfixed image on the heated material In the heating element used in the heating device,
The substrate has a positioning member for positioning a contact member that supplies power to the electrode portion, and the positioning member moves in the longitudinal direction of the substrate following the thermal expansion of the heating body. body.   The heating body according to claim 1, wherein the positioning member is fixedly attached to the substrate.   The heating body according to claim 1, wherein the positioning member is provided integrally with the substrate. A heating element having an elongated substrate, a heating resistor provided along the longitudinal direction of the substrate, and an electrode portion connected to the heating resistor; a contact member for supplying power to the electrode portion of the heating member; A flexible member that moves while being in contact with the heating body; and a pressure member that forms a nip portion with the heating body with the flexible member interposed therebetween, and the material to be heated is sandwiched between the nip portions. In an image heating apparatus for heating an unfixed image on the heated material while being conveyed,
The substrate of the heating body has a positioning member for positioning the contact member, and the positioning member moves in the longitudinal direction of the substrate following the thermal expansion of the heating body together with the contact member. Image heating device.   The image heating apparatus according to claim 4, further comprising a holding member that holds the heating body, wherein the holding member holds the heating body so as to be movable in a longitudinal direction of the substrate.