JP6143611B2 - Image heating device - Google Patents

Description

  The present invention relates to an image heating apparatus suitable for use as a fixing device (fixing device) mounted on an image forming apparatus such as an electrophotographic copying machine or an electrophotographic printer.

  2. Description of the Related Art A film heating type fixing device is known as a fixing device (fixing device) mounted on an electrophotographic printer or copying machine. This type of fixing device includes a heater having a resistance heating element on a ceramic substrate, a cylindrical film that moves while contacting the heater, and a pressure roller that forms a nip portion with the heater via the film. Have. The recording material carrying the unfixed toner image is heated while being nipped and conveyed by the nip portion of the fixing device, whereby the toner image on the recording material is heated and fixed to the recording material. This fixing device has an advantage that it takes a short time to start energizing the heater and raise the temperature to a fixable temperature. Therefore, a printer equipped with this fixing device can shorten the time (FPOT: First Print Out Time) from when a print command is input until the first image is output. This type of fixing device also has an advantage that power consumption during standby waiting for a print command is small.

  By the way, when a small-size recording material is continuously printed at the same print interval as a large-size recording material in a printer equipped with a fixing device using a film, an area where the recording material of the heater does not pass (non-passing area) is excessively increased. It is known to warm. When the temperature of the non-passing area of the heater is excessively high, members such as a holder that holds the heater and a pressure roller may be damaged by heat. Therefore, a printer equipped with a fixing device using a film has a control to widen the print interval when continuously printing on a small size recording material than when continuously printing on a large size recording material. Overheating is suppressed.

  However, the control to increase the print interval is to reduce the number of output sheets per unit time, and it is desired to suppress the number of output sheets per unit time of a small size recording material to be equal to or greater than that in the case of a large size recording material.

  Therefore, Patent Document 1 proposes a configuration in which a heat conducting member is arranged between the heater and the holder so as to equalize the heat in the heater longitudinal direction.

JP 11-84919 A

  Generally, in a film heating type fixing device, a heater is supported by a resin holder. A temperature detecting element (such as a thermistor) and a protective element (such as a thermal fuse) are placed in contact with a surface opposite to the surface that forms the fixing nip portion of the heater (hereinafter referred to as the heater back surface) or a resin spacer. Is arranged through.

  In a fixing device using a heater, a thermistor is connected to a secondary circuit, which is a control unit of the image forming apparatus, in order to control the power supplied to the heater based on the temperature detected by the temperature detection element. A protection element is connected to the primary circuit to cut off the energization from the commercial power source.

  Thus, the primary circuit and the secondary circuit are mixed on the heater back surface. Because the primary circuit and the secondary circuit need to be insulated from consideration of electric shock, the conductive heat conduction member placed on the back side of the heater as well as the temperature detection element and the protection element is divided into the primary circuit and the secondary circuit for insulation. It is necessary to ensure.

  However, if the distance (spatial distance) of the insulating portion between the heat conduction member of the primary circuit and the heat conduction member of the secondary circuit is made longer than necessary, the heat distribution in the heater longitudinal direction by the heat conduction member is made uniform. The effect may be reduced and image degradation may occur due to non-uniform heat distribution. In addition, since the heat stress of the heater becomes non-uniform, there is a possibility that the stress on the heater increases and the heater substrate is damaged.

  On the other hand, the insulation between the heat conduction member of the primary circuit and the heat conduction member of the secondary circuit needs to be secured in the same manner when noise such as lightning surge is applied from the commercial power supply. In this case, if the holder surface made of resin becomes a discharge path, the portion of the holder that has become the discharge path is carbonized (tracking occurs), causing breakdown voltage degradation, and it is difficult for the holder to maintain insulation performance. Become.

  An object of the present invention is to provide an image heating apparatus capable of making the heat distribution in the longitudinal direction of the heating member uniform and ensuring the insulating performance of the support member.

The configuration of the image heating apparatus according to the present invention for achieving the above object is an image heating apparatus for heating an image carried by a recording material,
A heating member;
A support member for supporting the heating member;
A conductive heat conducting member close to a primary circuit for energizing the heating member, the first heat conducting member disposed between the heating member and the support member;
A conductive heat conductive member proximate to a secondary circuit for controlling the temperature of the heating member, the second heat conductive member disposed between the heating member and the support member;
Have
The support member is provided with a recess or a protrusion so that the creepage distance of the surface of the support member between the first heat conductive member and the second heat conductive member is longer than the distance between the first heat conductive member and the second heat conductive member. Features.

  According to the present invention, it is possible to provide an image heating apparatus capable of making the heat distribution in the longitudinal direction of the heating member uniform and ensuring the insulating performance of the support member.

Cross section of image forming apparatus (A) is a cross-sectional view of the fixing device according to the first embodiment, and (b) is a front view of the heater. 1 is a block diagram illustrating a schematic configuration of a primary circuit and a secondary circuit of a heater of a fixing device according to a first embodiment. FIG. 3 is a perspective view illustrating a configuration example around a heater of the fixing device according to the first embodiment. FIG. 3 is a perspective view illustrating a configuration example around a heater of the fixing device according to the first embodiment. FIG. 3 is a perspective view illustrating a configuration example around a heater of the fixing device according to the first embodiment. Sectional drawing which shows the structural example of the heater periphery of the fixing device which concerns on Example 1. FIG. FIG. 3 is a front view illustrating a configuration example around a heater of the fixing device according to the first exemplary embodiment. Sectional drawing which shows the structural example of the heater periphery of the fixing device which concerns on Example 2. FIG. FIG. 9 is a front view illustrating a configuration example around a heater of a fixing device according to a second embodiment. Sectional drawing which shows the structural example of the heater periphery of the fixing device which concerns on Example 3. FIG. FIG. 9 is a front view illustrating a configuration example around a heater of a fixing device according to a third embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Although the preferred embodiment of the present invention is an example of the best embodiment of the present invention, the present invention is not limited by the following examples, and various other configurations are possible within the scope of the idea of the present invention. It is possible to replace this with a known configuration.

[Example 1]
(1) Image Forming Apparatus With reference to FIG. 1, an image forming apparatus in which the image heating apparatus according to the present invention is mounted as a fixing device will be described. FIG. 1 is a cross-sectional view illustrating a schematic configuration of an example of an image forming apparatus (full color printer in this embodiment) 100 using an electrophotographic recording technique.

  In the image forming apparatus 100, an image forming unit 101 that forms a toner image on a recording material P includes four image forming stations SY, SM, SC, and SBk of yellow, magenta, cyan, and black. Each image forming station includes a photosensitive drum 121 as an image carrier, a charging member 122, a laser scanner 123, a developing device 124, and a cleaner 125 for cleaning the photosensitive drum. Each image forming station further includes a transfer member 126, a belt 127 that conveys the toner image transferred from the photosensitive drum 121 by the transfer member, and a secondary transfer member 128 that transfers the toner image from the belt to the recording material P. Etc. Since the operation of the image forming unit 101 described above is well known, detailed description thereof is omitted.

  The recording material P stored in the cassette 111 in the image forming apparatus main body 100 </ b> A is fed out one by one by the rotation of the roller 112. The recording material P is conveyed to the secondary transfer nip portion formed by the belt 127 and the secondary transfer member 128 by the rotation of the roller 113. The recording material P onto which the toner image has been transferred at the secondary transfer nip portion is sent to a fixing device (fixing portion) 130, and the toner image is heated and fixed to the recording material by the fixing device. The recording material P exiting the fixing device 130 is discharged to the tray 115 by the rotation of the roller 114.

(2) Fixing device (image heating device) 130
Next, the configuration of the fixing device 130 and the heater 203 will be described with reference to FIG. 2A is a cross-sectional view illustrating a schematic configuration of the fixing device 103, and FIG. 2B is a front view illustrating a schematic configuration of the heater 203 from the film sliding surface side.

  In FIG. 2A, 202 is a holder (supporting member) having heat resistance and heat insulation. A concave portion 202a is formed in the holder 202 along a direction (hereinafter referred to as a longitudinal direction) orthogonal to the recording material conveyance direction of the holder. The recess 202a is formed in the center of a direction parallel to the recording material conveyance direction of the holder 202 (hereinafter referred to as the short direction). The recess 202a supports the ceramic heater (heating member) 203.

  Reference numeral 211 denotes a metal stay for imparting rigidity to the holder 202. The stay 211 is disposed along the longitudinal direction of the holder 202 on the opposite side of the ceramic heater (hereinafter referred to as a heater) 203.

  Reference numeral 201 denotes a cylindrical film (flexible member) having flexibility and heat resistance. As the film 201, a film using a resin material such as polyimide as a base layer or a metal material such as stainless steel can be used. Moreover, what laminated | stacked the rubber layer on the base layer may be used. The surface of the film is preferably provided with a release layer made of fluororesin or the like. The film 201 is loosely fitted on the outer periphery of a holder 202 having a stay 211 and a heater 203.

  As shown in FIGS. 2A and 2B, the heater (heating member) 203 has an elongated ceramic substrate 204. On the film sliding side surface (hereinafter referred to as the substrate surface) 204a of the substrate, heating element patterns (resistance heating elements) 205a and 205b that generate heat when energized are provided on both sides in the short direction of the substrate in the longitudinal direction of the substrate. It is formed along.

  The heating element patterns 205a and 205b are electrically connected to the electrodes 314a and 314b through conductive patterns 315a and 315b formed on one end side in the longitudinal direction of the substrate surface 204a, respectively. The heating element patterns 205a and 205b are connected in series via a conductive pattern 316 formed on the other longitudinal end of the substrate surface 204a. The heating element pattern 205 is covered with an electrical insulating layer 206 such as glass. The insulating layer 206 is formed as thin as possible to improve heat conduction.

  The heating element patterns 205a and 205b are connected to the commercial power supply 310 via a switching element such as the triac 308 shown in FIG. 3 and a mechanical switch element such as a relay (relay) 309. Then, by controlling ON / OFF of the triac 308 by the control unit 510 including a CPU and a memory such as a RAM and a ROM, the power supplied to the heating element patterns 205a and 205b is controlled. The ON / OFF control of the triac 308 is performed by pressing with a predetermined pressure in the vicinity of the heater, for example, a surface opposite to the front surface 204a of the substrate 204 (hereinafter referred to as the back surface of the substrate) 204b (see FIG. 2A). This is performed based on the value of the thermistor (temperature detection member) 207.

  A pressure roller 208 is disposed so as to face the heater 203 through the film 201. The pressure roller 208 is an elastic roller in which a heat-resistant elastic layer 210 such as silicone rubber is provided in a roller shape on the outer peripheral surface of a metal core or a metal pipe (hereinafter referred to as a pressure roller shaft) 209.

  In the fixing device 130 of this embodiment, both ends of the stay 211 in the longitudinal direction are supported by a frame (not shown) of the fixing device, and both ends in the longitudinal direction of the pressure roller shaft 209 of the pressure roller 208 are rotatably supported. I am letting. Then, both ends in the longitudinal direction of the stay 211 are pressed in a direction perpendicular to the generatrix direction of the film 211 by pressurizing springs (not shown). When the stay 211 is pressurized, the heater 203 is pressed against the pressure roller 208 via the film 211. As a result, the heat-resistant elastic layer 210 of the pressure roller 208 is crushed and elastically deformed, and is necessary for heating and fixing an unfixed toner image (image) between the outer peripheral surface (surface) of the film and the outer peripheral surface (surface) of the pressure roller. A nip portion N (see FIG. 2) having a predetermined width is formed.

  With reference to FIG. 2, the heat fixing processing operation of the fixing device 130 will be described. The pressure roller 208 is rotated in the direction of the arrow by a driving force of a motor (not shown) provided in the image forming apparatus main body 100A. The film 201 rotates in the direction of the arrow following the rotation of the pressure roller 208 while the inner peripheral surface (inner surface) of the film slides on the electrical insulating layer 210 of the heater 203.

  The heating element pattern 205 of the heater 203 generates heat due to electric power supplied from the commercial power supply 310 via the triac 308 (see FIG. 3), and the heater rapidly rises in temperature. The controller 510 controls the power supplied to the heater by controlling ON / OFF of the triac 308 so that the temperature detected by the thermistor 207 that monitors the temperature of the heater 203 maintains the fixing temperature (target temperature).

  While the recording material P carrying the unfixed toner image T is nipped and conveyed at the nip portion N, the heat of the heater 203 and the pressure of the nip portion are applied to the unfixed toner image, whereby the toner image is heated and fixed on the recording material. The

(3) Configuration of Primary Circuit Pc and Secondary Circuit Sc of Heater 203 FIG. 3 is a block diagram showing a schematic configuration of primary circuit Pc and secondary circuit Sc of heater 203.

  In the primary circuit Pc, the heating element patterns 205a and 205b of the heater 203 are electrically connected to the metal contacts 313a and 313b of the connector 312 through the electrodes 314a and 314b. The metal contacts 313 a and 313 b are connected to the commercial power supply 310 via the triac 308 and the relay 309 on one side of the positive electrode and the negative electrode, and are connected to the commercial power supply 310 via the temperature fuse 307. Then, the power supplied to the heating element patterns 205a and 205b is controlled by ON / OFF control of the triac 308.

  417a and 417b are Y capacitors, 418a and 418b are X capacitors, and 419 is a common mode choke coil. Here, detachable drawer connectors 311 a and 311 b are used at locations where the fixing device 130 is electrically connected to the image forming apparatus 100.

  A thermal fuse (protective element) 307 is pressed against the substrate back surface 204b of the heater 203 with a predetermined pressure via a first heat conducting member described later, and shuts off the primary circuit when an abnormal temperature rise occurs in the heater. It has a function.

  Reference numeral 320 denotes a conductive first heat conductive member adjacent to the primary circuit Pc. The first heat conducting member 320 is disposed between the thermal fuse 307 and the substrate back surface 204 b of the heater 203. One surface of the first heat conducting member 320 is in contact with the heater 203, and the other surface is in contact with the thermal fuse 307.

  In the secondary circuit Sc, the thermistor 207 is pressed against the substrate back surface 204b of the heater 203 with a predetermined pressure via a second heat conducting member to be described later, and detects the temperature of the heater.

  Reference numeral 220 denotes a conductive second heat conducting member adjacent to the secondary circuit Sc. The second heat conducting member 220 is disposed between the thermistor 207 and the substrate back surface 204 b of the heater 203. One surface of the second heat conducting member 220 is in contact with the heater 203, and the other surface is in contact with the thermistor 207. The second heat conducting member 220 is arranged at a predetermined interval (a spatial distance 335 described later) in order to ensure insulation from the first heat conducting member 320 in the longitudinal direction of the holder 202.

  Removable connectors 511a and 511b are disposed at locations where the fixing device 130 is electrically connected to the image forming apparatus 100. The connection path of the thermistor 207 is connected to the control unit 510 of the image forming apparatus 100 via the connectors 511a and 511b, and the voltage value divided by the resistance value corresponding to the DC power source 516, the resistor 517, and the temperature of the thermistor is controlled. Is input to the department.

  The first heat conducting member 320 and the second heat conducting member 220 as described above in “Background Art” make the heat in the heater longitudinal direction uniform by taking measures against excessive temperature rise in the non-passing region of the heater 203. To be provided. The first heat conductive member 320 and the second heat conductive member 220 are formed using a material having higher heat conductivity than the substrate 204 of the heater 203. The material of the first heat conducting member 320 and the second heat conducting member 220 in this embodiment is aluminum.

  The first heat conducting member 320 is treated as a primary circuit because it is close to (or in contact with) the thermal fuse 307 in the primary circuit Pc for energizing the heating element patterns 205a and 205b. The second heat conducting member 220 is treated as a secondary circuit because it is close to (or in contact with) the thermistor 207 in the secondary circuit Sc for controlling the temperature of the heater 203. Hereinafter, for convenience of explanation, the first heat conducting member 320 is referred to as a primary side heat conducting member. The second heat conducting member 220 is referred to as a secondary side heat conducting member.

  The primary side heat conduction member 320 and the secondary side heat conduction member 220 need to be arranged at a distance from each other in order to insulate the primary side heat conduction member and the secondary side heat conduction member. On the other hand, as described in “Problems to be Solved by the Invention”, this distance is within an appropriate range that does not cause problems such as image degradation and heater substrate breakage due to uneven thermal stress of the heater. Must be set.

(4) Arrangement Configuration of Primary Heat Conducting Member 320 and Secondary Heat Conducting Member 220 Hereinafter, referring to FIGS. 4 to 8, the primary heat conducting member 320 and the secondary heat conducting member 220 with respect to the holder 202 are arranged. The arrangement configuration will be described.

  As described above, considering the effect of heat uniformity in the heater longitudinal direction, the distance between the primary side heat conduction member 320 and the secondary side heat conduction member 220 should be as short as possible. On the other hand, when a high voltage such as a common mode induced lightning is applied to the commercial power supply 310, a discharge may occur between the primary side heat conduction member 320 and the secondary side heat conduction member 220.

  4 to 6 show a positional relationship among the thermistor 207, the thermal fuse 307, the primary side heat conduction member 320, the secondary side heat conduction member 220, and the heater 203 arranged in the holder 202. FIG. FIG. 7 shows a cross-sectional view of the holder 202 in which the thermistor 207, the thermal fuse 307, the primary side heat conduction member 320, the secondary side heat conduction member 220, and the heater 203 are arranged.

  FIG. 4 is a perspective view of the holder 202 to which the thermistor 207 and the thermal fuse 307 are attached as viewed from the pressure roller 208 side. In FIG. 4, 324 a and 324 b are holes for attaching the primary side heat conduction member 320. 224a and 224b are holes for attaching the secondary heat conduction member 220. These holes 324a, 324b, 224a, 224b are each formed in an L shape as shown in FIG.

  FIG. 5 is a perspective view of the holder 202 to which the primary side heat conducting member 320 and the secondary side heat conducting member 220 are attached as viewed from the pressure roller 208 side. The primary side heat conducting member 320 has a U shape, and is attached to the holder 202 so that the bent portions 320a and 320b at both ends in the longitudinal direction are inserted into the holes 324a and 324b from the pressure roller side (not shown). Further, the ends of the bent portions 320 a and 320 b are bent to form the hook portions 320 a 1 and 320 b 1, whereby the primary side heat conduction member 320 is locked to the holder 202.

  Similarly, the secondary side heat conducting member 220 is attached to the holder 202 by inserting the bent portions 220a and 220b at both ends in the longitudinal direction into the holes 224a and 224b from the pressure roller side (not shown). Further, the ends of the bent portions 220 a and 220 b are bent to form the hook portions 220 a 1 and 220 b 1, whereby the secondary side heat conduction member 220 is locked to the holder 202.

  FIG. 6 is a perspective view of the holder 202 to which the heater 203 is attached and fixed as viewed from the pressure roller 208 side. In FIG. 6, x indicates the longitudinal direction, y indicates the short direction, and z indicates the height direction.

  As shown in FIG. 6, the heater 203 is attached to the holder 202 so that the heater 203 is in contact with the primary side heat conduction member 320 and the secondary side heat conduction member 220. The heater 203 is fixed to the holder 202 by a sheet metal 322. The connector 312 having a substantially U-shaped cross section in the short direction is meshed with the holder 202 when connecting to the electrodes 314 a and 314 b of the heater 203. That is, the connector 312 also plays a role of fixing one end of the heater 203 in the longitudinal direction to the holder 202 (see FIG. 7). When the connector 312 is engaged with the holder 202, the electrode (not shown) of the connector is electrically connected to the electrodes 314a and 314b of the heater 203, and the electric power can be supplied.

  A gap 333 provided in the holder between the primary side heat conductive member 320 and the secondary side heat conductive member 220 will be described with reference to FIGS. 4, 7, and 8.

  If a lightning surge voltage is applied to the commercial power supply 310 and discharge occurs, a current propagates from the thermal fuse 307 to the primary side heat conducting member 320. Then, discharge is performed from the end portion 340 (see FIG. 7) of the bent portion 320b to the end portion 240 (see FIG. 7) of the bent portion 220a where the distance between the primary side heat conductive member 320 and the secondary side heat conductive member 220 is closest. Then, a current flows through the thermistor 207 to the secondary side ground.

  By the way, since the holder 202 is generally formed of a resin mold material because of cost and processing advantages, when the holder 202 is discharged through the creeping surface of the holder, the portion is carbonized to cause deterioration in pressure resistance.

  Therefore, in this embodiment, a gap (hereinafter referred to as a recess) 333 is provided in the holder portion located between the end portion 340 and the end portion 240. The creeping distance in the x direction of the holder is set to be long as point 333a-point 333b-point 333c-point 333d (see FIG. 7). As a result, even if a discharge from the end 340 to the end 240 occurs, the discharge is performed in a space connecting the point 333a and the point 333d with a straight line. Thereby, the creeping discharge transmitted on the holder 202 surface (support member surface) can be prevented, and the pressure | voltage resistance deterioration by carbonization path formation can be suppressed. Further, when the discharge from the end portion 340 to the end portion 240 occurs, the substrate 204 of the heater 203 is ceramic, so that carbonization and breakdown voltage deterioration do not occur even if the discharge is made through the substrate surface.

  8 is a front view of the holder 202 shown in FIG. 5 as viewed from the substrate rear surface 204b side of the heater 203. The concave portion 333 of the holder 202, the hole 324b of the primary side heat conduction member 320, and the secondary side heat conduction member 220 are shown. , 224b in the y direction.

  As shown in FIG. 8, the width of the recess 333 in the y direction is larger than the width of the primary side heat conduction member 320 and the secondary side heat conduction member 220. Thereby, the creepage distance through the points 333e and 333f of the holder 202 becomes longer than the spatial distance 335 connecting the end portion 340 and the end portion 240, and it is possible to suppress the breakdown voltage deterioration due to the creeping discharge of the holder. Thus, not only the creepage distance (point 333a-point 333b-point 333c-point 333d via distance) shown in FIG. 7, but also the creepage distance (point 333e-point 333f via distance) shown in FIG. Even longer than the spatial distance. By providing the concave portion having such a size, it is possible to suppress the breakdown voltage degradation.

  In the present embodiment, the widths of the primary side heat conduction member 320 and the secondary side heat conduction member 220 are made narrower than the width of the recess 333 in the y direction. However, at least one of the widths of the primary side heat conduction member 320 and the secondary side heat conduction member 220 may be narrower than the width of the recess 333 to suppress creeping discharge.

[Example 2]
Another example of the fixing device 130 will be described. FIG. 9 shows a cross-sectional view of the holder 202 in which the thermistor 207, the thermal fuse 307, the primary side heat conduction member 320, the secondary side heat conduction member 220, and the heater 203 are arranged. FIG. 10 is a front view of the holder 202 shown in FIG. 9 as viewed from the substrate rear surface 204b side of the heater 203. , 224b in the y direction.

  The fixing device 130 shown in the present embodiment has the same configuration as the fixing device 130 of the first embodiment, except that the holder 202 is provided with a convex portion 334 instead of the concave portion 333.

  As shown in FIGS. 9 and 10, the holder 20 communicates with these holes between a hole 324 b for fixing the primary side heat conducting member 320 and a hole 224 b for fixing the secondary side heat conducting member 220. An opening 337 is provided along the longitudinal direction of the holder. A convex portion 334 is provided inside the opening 337 along the y direction of the holder 202. As a result, the creepage distance (point 334a-point 334b-point 334c-point 334d) that travels through the holder 202 becomes longer than the spatial distance 335 that connects the end 340 and the end 240. Thereby, it becomes possible to suppress the pressure | voltage resistant deterioration by the creeping discharge of a holder.

  As shown in FIG. 10, the opening 337 has a shape in which the holes 324 b and 224 b of the opening 337 are narrowed. This is performed in order to suppress backlash in the y direction between the primary side heat conduction member 320 and the secondary side heat conduction member 220. If the opening 337 is rectangular and the bent portion 320a of the primary side heat conducting member 320 and the bent portion 220a of the secondary side heat conducting member 220 abut against the holder 202 around the opening 337 in the y direction, the creepage distance is short. This is because there is a possibility of becoming. Even if the opening 337 is rectangular, the bent portion 320a of the primary side heat conducting member 320 and the bent portion 220a of the secondary side heat conducting member 220 do not hit the long side portion of the rectangular opening 337 in the y direction. If movement is restricted, there is no problem.

[Example 3]
Another example of the fixing device 130 will be described. FIG. 11 shows a cross-sectional view of the holder 202 in which the thermistor 207, the thermal fuse 307, the primary side heat conduction member 430, the secondary side heat conduction member 420, and the heater 203 are arranged. FIG. 12 is a front view of the holder 202 shown in FIG. 11 as viewed from the substrate rear surface 204b side of the heater 203. The positional relationship of the y direction of the heat conductive member 420 is represented.

  The fixing device 130 shown in this embodiment prints the primary side heat conduction member 430 and the secondary side heat conduction member 420 on the substrate back surface 204b of the heater 203 in that a gap (hereinafter referred to as a recess) 433 is provided in the holder 202. Except for this point, the configuration is the same as that of the fixing device 130 of the first embodiment.

  The primary side heat conduction member 430 and the secondary side heat conduction member 420 are directly printed on the substrate back surface 204 b of the heater 203. That is, the primary side heat conduction member 430 and the secondary side heat conduction member 420 are formed in the heater 203. As a result, it is not necessary to provide the holder 202 with a hole for fixing the heat conducting member as in the first and second embodiments, and the configuration of the holder can be simplified.

  The holder 202 has a rectangular shape whose length in the y direction is longer than a spatial distance 336 (see FIG. 12) connecting the longitudinal end portion 430a of the primary side heat conducting member 430 and the longitudinal end portion 420a of the secondary side heat conducting member 420. The recess 433 is provided. As a result, the creepage distance (distance via 433a-433b-433c-433d) (see FIG. 11) that travels through the holder 202 becomes longer than the spatial distance 336, and it is possible to suppress the breakdown voltage degradation due to creeping discharge of the holder. Become. Since the shapes of the primary side heat conduction member 430 and the secondary side heat conduction member 420 are not U-shaped as in the first and second embodiments, the concave portion 433 can be formed in a simple rectangular shape. .

  The fixing device 130 shown in the present embodiment has a simpler configuration with fewer parts than the fixing device 103 of the first and second embodiments.

[Other embodiments]
The image heating device according to the present invention is not limited to use as a fixing device as in the embodiments. It can also be effectively used as an image modifying device for modifying the glossiness of an image once fixed on a recording material (fixed image) or an assumed image (semi-fixed image).

130: fixing device, 202: holder, 203: heater, 207: thermistor, 220, 420: second heat conducting member, 307: thermal fuse, 320, 430: first heat conducting member, 333, 433: recess, 334: convex portion, P: recording material, Pc: primary circuit, Sc: secondary circuit, T: unfixed toner image

Claims (8)

An image heating apparatus for heating an image carried by a recording material,
A heating member;
A support member for supporting the heating member;
A conductive heat conducting member close to a primary circuit for energizing the heating member, the first heat conducting member disposed between the heating member and the support member;
A conductive heat conductive member proximate to a secondary circuit for controlling the temperature of the heating member, the second heat conductive member disposed between the heating member and the support member;
Have
The support member is provided with a recess or a protrusion so that the creepage distance of the surface of the support member between the first heat conductive member and the second heat conductive member is longer than the distance between the first heat conductive member and the second heat conductive member. An image heating apparatus.   The image heating apparatus according to claim 1, wherein the first heat conducting member and the second heat conducting member are locked to the support member.   The image heating apparatus according to claim 1, wherein the first heat conducting member and the second heat conducting member are formed on the heating member.   The image heating apparatus according to any one of claims 1 to 3, wherein the heating member is a ceramic heater.   The primary circuit is connected to a protective element that cuts off power to the heating member when an abnormal temperature rise occurs in the heating member, and the protective element is in contact with the first heat conducting member. The image heating apparatus according to claim 1, wherein the image heating apparatus is an image heating apparatus.   The secondary circuit is connected to a temperature detection member for detecting the temperature of the heating member and controlling power supplied to the heating member, and the temperature detection member is in contact with the second heat conducting member. The image heating apparatus according to claim 1, wherein the image heating apparatus is an image heating apparatus.   The image according to any one of claims 1 to 6, wherein the first heat conductive member and the second heat conductive member are made of a material having higher heat conductivity than the heating member. Heating device.   The at least one of the widths of the first heat conductive member or the second heat conductive member is narrower than the concave portion or the convex portion in the short direction of the heating member. Item 8. The image heating apparatus according to any one of Items 7 to 9.