JP2011118246A - Image heating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image heating device capable of reducing a quantity of heat transmitted from a holding member of a heat generating member to a conductive member which electrically connects a control part and a temperature detecting member when the conductive member comes into contact with the holding member, and capable of reducing manufacturing cost. <P>SOLUTION: The image heating device includes: a flexible cylindrical film 306; a ceramic substrate 302; a heater holder 301 with a holding part 311 which holds the ceramic substrate 302 formed thereon; a thermistor 403 configured to detect the temperature of the ceramic substrate 302; a thermoswitch 401; an electrical wire 404; an electrical wire 402; and a pressure roller 307 where the thermistor 403, the thermoswitch 401 and a control part are connected to one another through the electrical wires 404 and 402, and the electrical wires 404 and 402 are supported to a plurality of projections 301a formed at the heater holder 301. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image heating apparatus that heats an image formed on a sheet material.

  Conventionally, an image forming apparatus that employs an electrophotographic system is provided with an image heating apparatus that heat-fixes an unfixed toner image transferred onto a sheet material on the sheet material. In addition, a configuration is known in which an image heating apparatus is used as a gloss imparting unit that increases the gloss of an image by heating the image.

  FIG. 5 shows a schematic configuration of a conventional image heating apparatus. The image heating apparatus shown in FIG. 5 has a flexible sleeve member 36 and a pressure roller 37 that is rotated by a driving means (not shown), and a sheet material at a nip portion formed by pressure contact between them. By sandwiching and conveying the image, the image on the sheet material is heated. Such an image heating apparatus is referred to as a “surf type” image heating apparatus.

  According to the surf type image heating apparatus, the side of the ceramic substrate 32 where the heating resistor pattern 33 is formed (the side covered with the glass coat 34) slides directly with the inner peripheral surface of the sleeve member 36. Heat can be efficiently transferred to the sheet material at the portion. Therefore, it is possible to shorten the startup time until the temperature of the nip portion reaches a predetermined temperature and to reduce power consumption. Patent Document 1 discloses a configuration of a conventional surf type image heating apparatus.

JP-A-6-314040

  The image heating apparatus employing the conventional surf method has the following problems.

  As shown in FIG. 5, the image heating apparatus is provided with a thermistor 43 (temperature detection member) that contacts the ceramic substrate 32 and detects the temperature of the ceramic substrate 32, and the thermistor 43 is not shown by the conducting member 44. It is electrically connected to the control unit. Thereby, based on the temperature detected by the thermistor 43, the control unit controls energization to the heating resistor pattern 33, so that the temperature of the nip portion can be kept within an appropriate range.

  Further, as shown in FIG. 4, the image heating apparatus is a thermostat that detects an abnormal temperature rise of the ceramic substrate 32 as an excessive temperature rise detection member and stops the image heating operation via the control unit or the like. A switch 41 is provided. 4 is a schematic configuration when the image heating apparatus shown in FIG. 5 is viewed from the sheet material conveying direction.

  As shown in FIG. 4, one end of the thermistor 43 and the thermo switch 41 passes through the holding member 31 that holds the ceramic substrate 32 and is in contact with the ceramic substrate 32. The other end is connected to the conductive members 44 and 42 on the back surface of the holding member 31 (the surface opposite to the ceramic substrate 32).

However, in such a configuration, the heat of the ceramic substrate 32 is transmitted to the holding member 31, so that the holding member 31 becomes high temperature. Since the conductive members 44 and 42 are disposed on the back surface of the holding member 31 in contact with the holding member 31, the conductive members 44 and 42 are formed of a material having excellent heat resistance, or conductive with such a material. It is necessary to take measures such as protecting the members 44 and 42. Therefore, in the conventional configuration, there is a problem in that the material used for the conductive members 44 and 42 or the configuration thereof is restricted in design, which leads to an increase in manufacturing cost.

  Therefore, the present invention provides a temperature detection member, a conductive member that electrically connects the overheat detection member and the control unit, provided on the holding member that holds the heat generating member. An object of the present invention is to provide an image heating apparatus capable of reducing the amount of heat transmitted to the image.

  In order to achieve the above object, in the present invention, a flexible rotatable sleeve member, a heat generating member that generates heat when energized, a rotation shaft of the sleeve member inside the sleeve member, and A holding member that is arranged substantially in parallel and holds the heat generating member in contact with the inner peripheral surface of the sleeve member; a temperature detecting member that is provided on the holding member and detects the temperature of the heat generating member; An overtemperature detecting member provided on the holding member and detecting an excessive temperature rise of the heat generating member; and a pressure rotating body provided opposite to the heat generating member and press-contacting the sleeve member to form a nip portion; In the image heating apparatus that heats an image on the sheet material by nipping and conveying the sheet material at the nip portion, energization to the heat generating member is controlled based on the detection result of the temperature detection member. And a controller that switches on / off of the image heating operation based on a detection result of the overheat detection member, and each of the temperature detection member and the overheat detection member are on the surface of the holding member. A plurality of protrusions that support the conducting member are provided in a region where the conducting member is provided on the surface of the holding member. Features.

  As described above, according to the present invention, when the temperature detection member, the conductive member that electrically connects the overheat detection member and the control unit are disposed on the holding member that holds the heat generating member. An image heating apparatus capable of reducing the amount of heat transmitted from the holding member to the conducting member can be provided.

1 is a schematic configuration diagram of an image heating apparatus according to a first embodiment. The schematic block diagram of the image heating apparatus which concerns on 2nd Embodiment. FIG. 6 is a schematic configuration diagram of an image heating apparatus according to a third embodiment. 1 is a schematic configuration diagram of a conventional image heating apparatus. 1 is a schematic configuration diagram of a conventional image heating apparatus.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be exemplarily described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like 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.

<First Embodiment>
An image heating apparatus according to a first embodiment of the present invention will be described with reference to FIG. FIG. 1A is a schematic configuration diagram of the image heating apparatus according to the present embodiment as viewed from the conveying direction of the sheet material, and FIG. 1B illustrates the image heating apparatus according to the present embodiment as a sheet material. It is the schematic block diagram seen from the direction orthogonal to the conveyance direction.

(Schematic configuration of image heating device)
With reference to FIG. 1A and FIG. 1B, a schematic configuration of the image heating apparatus according to the present embodiment will be described. The image heating apparatus includes a rotatable cylindrical film 306 (sleeve member) having flexibility, and a pressure roller 307 (pressure rotator) that presses against the film to form a nip portion. By sandwiching and conveying the sheet material at the nip portion, the image on the sheet material can be heated. The pressure roller 307 is configured to rotate by receiving a driving force transmitted from a driving source (not shown). The cylindrical film 306 that is in pressure contact with the pressure roller 307 is in contact with the pressure roller 307. It is configured to follow and rotate.

  Inside the cylindrical film 306, a ceramic substrate 302 (heating member) on which a heating resistance pattern 303 is printed is provided. The surface on the side of the heating resistor pattern 303 is covered with a glass coat 304 for insulation protection, and the ceramic substrate 302 and the cylindrical film 306 are formed on the surface on which the heating resistor pattern 303 and the glass coat 304 are formed. Is slidably in contact with the inner peripheral surface.

  The ceramic substrate 302 is configured to generate heat when the heating resistor pattern 303 is energized by energization means (not shown). In addition, grease is applied to the surface of the ceramic substrate 302 on the side that slides with the inner peripheral surface of the cylindrical film 306 in order to ensure good slidability.

  Inside the cylindrical film 306, the ceramic substrate 302 is held by a heater holder 301 (holding member) provided substantially parallel to the cylindrical film 306. The heater holder 301 is formed with a holding portion 311 for holding the ceramic substrate 302. By fitting the ceramic substrate 302 into the holding portion 311, the ceramic substrate 302 is brought into contact with the inner peripheral surface of the cylindrical film 306. It becomes possible to hold in the state.

  The heater holder 301 has a substantially U-shaped cross-sectional shape, and plays a role of guiding the rotation of the cylindrical film 306 at the protruding portions on both sides of the holding portion 311. The heater holder 301 in the present embodiment is integrally molded from a resin material, but the material used for the heater holder 301 is not limited to this, and conditions such as heat resistance and strength are used. Other materials may be used as long as the material satisfies the above.

  A metal frame member 305 is attached to the heater holder 301 from the upper side in the figure. The frame member 305 has a curved shape, and is configured so that the cylindrical film 306 can smoothly rotate along the frame member 305.

  As shown in FIG. 1A, the thermistor 403 (temperature detection member) and the thermo switch 401 (overtemperature rise detection member) are in contact with the surface of the ceramic substrate 302 on the holding portion 311 side. The thermistor 403 detects the temperature of the ceramic substrate 302 and transmits the detection result to a control unit (not shown) through an electric wire 404 (conduction member) described later. The thermo switch 401 detects an excessive temperature rise of the ceramic substrate 302 and transmits it to a control unit (not shown) through an electric wire 402 described later to switch on / off of the image heating operation. In FIG. 1B, only the thermistor 403 is shown, but the thermo switch 401 is provided in the vicinity of the thermistor 403 (the back side in FIG. 1B), both of which are shown in FIG. 1A. In the vicinity of the sheet material conveyance center line.

By providing the thermistor 403 and the thermo switch 401 in this manner, the temperature at the nip portion can be maintained in an appropriate range, and the image heating operation can be performed in a state where the nip portion is overheated. Can be prevented. Furthermore, by disposing the thermistor 403 and the thermo switch 401 in the vicinity of the sheet material conveyance center, it is possible to detect the temperature of the nip portion in almost all sizes of the sheet material that can be passed. Become. However, the location of the thermistor 403 and the thermo switch 401 is not limited to this.

  As shown in FIG. 1A, the thermistor 403 and the thermo switch 401 are provided so as to be exposed to the ceramic substrate 302 side from the hole formed in the heater holder 301. More specifically, the thermistor 403 and the thermo switch 401 are fitted into the hole formed in the heater holder 301 from the surface of the heater holder 301 opposite to the ceramic substrate 302 (hereinafter referred to as the back surface), and the tip of the ceramic substrate 302 is fitted. Is in contact with

  Further, from the back surface side, the thermistor 403 and the thermo switch 401 are urged toward the ceramic substrate 302 by pressure springs 406 and 405, respectively. Accordingly, the thermistor 403 and the thermo switch 401 can be attached to the heater holder 302 in a state where the thermistor 403 and the thermo switch 401 are in contact with the ceramic substrate 302.

  Further, since the thermistor 403 and the thermo switch 401 are energized by the pressure springs 406 and 405, they are in contact with the ceramic substrate 302 while maintaining a stable state without being affected by the rotational state of the cylindrical film 306. Can be made. Thereby, the temperature detection accuracy of the thermistor 403 and the thermo switch 401 can be improved.

  In this embodiment, the pressure springs 406 and 405 are interposed between the thermistor 403, the thermo switch 401, and the frame member 305. For example, a plate spring is attached to the back surface of the heater holder 301. Also good. According to this configuration, the thermistor 403 and the thermo switch 401 can be biased with respect to the ceramic substrate 302 using the elasticity of the leaf spring.

(Configuration to reduce the amount of heat transmitted to the conductive member)
In the image heating apparatus described above, the thermistor 403 is electrically connected to a control unit (not shown) provided outside the apparatus main body by an electric wire 404 (conduction member). Accordingly, the control unit controls energization to the heating resistor pattern 303 according to the detection result of the thermistor 403, and the temperature of the nip portion can be maintained in an appropriate range. In addition, when the thermo switch 401 detects an overtemperature of the ceramic substrate 302 by connecting the thermo switch 401 and the control unit outside the apparatus main body by the electric wire 402 (conductive member), the image heating operation is performed via the control unit. Can be switched on and off.

  The electric wire 404 and the electric wire 402 used here are disposed on the heater holder 301 (on the holding member), and contact the back surface of the heater holder 301 to rotate the cylindrical film 306 from the thermistor 403 and the thermo switch 401, respectively. It extends in the axial direction. However, in such a configuration, when the contact area between the electric wire 404 and the electric wire 402 and the heater holder 301 is large, the heater holder 301 is in a high temperature state due to the heat transmitted from the ceramic substrate 302, and thus the electric wire 404 and the electric wire 402 have a large amount of heat. Will be transmitted.

  Therefore, in the present embodiment, a plurality of protrusions 301 a are formed along the rotation axis direction of the cylindrical film 306 in the region where the electric wires 404 and 402 are provided on the surface of the heater holder 301. And it is set as the structure which supports the electric wire 404 and the electric wire 402 by these protrusion 301a (FIG. 1 (a)).

According to this configuration, the contact area between the electric wire 404 and the electric wire 402 and the heater holder 301 can be reduced, so that the amount of heat transferred from the heater holder 301 to the electric wire 404 and the electric wire 402 can be reduced. Therefore, the selection range of materials applicable to the electric wire 404 and the electric wire 402 is widened as compared with the conventional image heating apparatus in which a material having excellent heat resistance is required for the electric wire (the heat resistance is lower than the conventional one). Manufacturing materials can be reduced.

  As described above, according to the present embodiment, it is possible to provide an image heating apparatus that can reduce the amount of heat transferred from the heater holder 301 to the electric wires 404 and 402 and reduce the manufacturing cost.

(Second Embodiment)
An image heating apparatus according to a second embodiment of the present invention will be described with reference to FIG. FIG. 2 is a schematic configuration diagram when the image heating apparatus according to the present embodiment is viewed from the conveyance direction of the sheet material. Since the schematic configuration of the image heating apparatus is the same as that of the first embodiment, description thereof is omitted here.

  As shown in FIG. 2, the present embodiment is characterized in that a plurality of grooves 301b are formed on the contact surface of the holding portion 311 of the heater holder 301 with the ceramic substrate 302.

  Thereby, the contact area between the heater holder 301 and the ceramic substrate 302 can be reduced, so that the amount of heat transferred from the ceramic substrate 302 to the heater holder 301 can be reduced. Furthermore, the amount of heat transferred from the heater holder 301 to the protrusion 301a can be more effectively reduced by disposing the groove 301b and the protrusion 301a so that the protrusion 301a comes to the back surface of each groove 301b. It becomes possible.

  Therefore, the amount of heat transferred from the heater holder 301 to the electric wires 404 and 402 can be further reduced. As a result, the selection range of materials applicable to the electric wire 404 and the electric wire 402 is expanded as compared with a conventional image heating apparatus that needs to use a material having excellent heat resistance (a material having lower heat resistance than the conventional one). Manufacturing cost can be reduced.

  In this embodiment, the protrusion 301a is provided on the back surface of the heater holder 301. However, even if the protrusion 301a is not provided, the amount of heat transmitted from the ceramic substrate 302 is reduced by forming the groove 301b. Therefore, it is possible to obtain the above effect. Further, even when the groove 301b and the protrusion 301a are not located at positions facing each other, the above-described effect can be obtained.

  The dimensions and number of the grooves 301b are appropriately selected in view of the strength of the heater holder 301 and the like. For example, when the dimension of the groove 301b is increased or the number of the grooves 301b is increased, the amount of heat transmitted from the ceramic substrate 302 can be reduced more effectively, but the strength of the heater holder 301 is reduced. Therefore, these settings may be set to appropriate values in view of the strength of the heater holder 302 and the like.

  As described above, according to the present embodiment, it is possible to provide an image heating apparatus that can reduce the amount of heat transferred from the heater holder 301 to the electric wires 404 and 402 and reduce the manufacturing cost.

(Third embodiment)
An image heating apparatus according to a third embodiment of the present invention will be described with reference to FIG. FIG. 3 is a schematic configuration diagram when the image heating apparatus according to the present embodiment is viewed from a direction orthogonal to the conveyance direction of the sheet material. Since the schematic configuration of the image heating apparatus is the same as that of the first embodiment, description thereof is omitted here.

  In the present embodiment, a protrusion 501a similar to that described in the first embodiment is formed on the back surface of the heater holder 501, and a groove 501b (holding portion) for holding the electric wire 404 (402) at the tip thereof. Is formed. Further, the groove 501c described in the second embodiment is formed in the holding portion 511 of the heater holder 501, and the amount of heat transmitted from the ceramic substrate 302 is reduced.

  According to such a configuration, the electric wire 404 can be reliably held at the tip of the protrusion 501a. Thereby, the electric wire 404 can be prevented from slipping off from the upper surface of the protrusion 501a. Further, it is possible to prevent the problem that the electric wire 404 is bent and the electric wire 404 contacts the back surface of the heater holder 501 between the plurality of protrusions 501a.

  In this embodiment, the electric wire 404 (402) is held by the groove 501b provided on the upper surface of the protrusion 501a. However, the shape of the holding portion is not limited to this. For example, if it is a member and shape which can hold | maintain an electric wire collectively, you may apply it as a holding part for electric wires.

  Therefore, the selection range of materials applicable to the electric wire 404 is expanded as compared with a conventional image heating apparatus that needs to use a material having excellent heat resistance (the use of a material having lower heat resistance than the conventional one). Manufacturing cost can be reduced.

  As described above, according to the present embodiment, it is possible to provide an image heating apparatus that can reduce the amount of heat transferred from the heater holder 501 to the electric wire 404 and reduce the manufacturing cost.

301 Heater Holder 301a Protrusion 302 Ceramic Substrate 303 Heating Resistance Pattern 306 Cylindrical Film 307 Pressure Roller 311 (Heater Holder) Holding Part 401 Thermo Switch 402 Electric Wire 403 Thermistor 404 Electric Wire

Claims (4)

A rotatable sleeve member having flexibility;
A heating member that generates heat when energized;
A holding member that is disposed substantially parallel to the rotation axis of the sleeve member inside the sleeve member and holds the heat generating member in contact with the inner peripheral surface of the sleeve member;
A temperature detection member provided on the holding member for detecting the temperature of the heat generating member;
An overtemperature detection member provided on the holding member for detecting an overtemperature rise of the heating member;
A pressure rotating body that is provided facing the heat generating member and that presses against the sleeve member to form a nip portion, and
In the image heating apparatus that heats the image on the sheet material by nipping and conveying the sheet material in the nip portion,
A controller for controlling energization to the heat generating member based on the detection result of the temperature detection member and switching on / off of the image heating operation based on the detection result of the overheat detection member; and the temperature detection member And each of the excessive temperature rise detection members,
Electrically connected by a conducting member provided on the surface of the holding member;
An image heating apparatus, wherein a plurality of protrusions for supporting the conducting member are provided in a region where the conducting member is provided on a surface of the holding member. In the holding member,
The image heating apparatus according to claim 1, wherein a plurality of grooves are formed on a surface facing the heat generating member. The protrusion is
The image heating apparatus according to claim 2, wherein the image heating apparatus is provided at a position facing the groove. At the tip of the protrusion,
The image heating apparatus according to claim 1, wherein a holding portion that holds the conductive member is formed.

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