JP2006331950A - Ceramic heater, heating apparatus, and image processing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize a ceramic heater wherein good fixing characteristic can be obtained without lowering the sliding characteristic and the durability of apparatus is improved. <P>SOLUTION: Heating resistors 121, 122, made of such as silver-palladium, which are heated by energization; and power supply electrodes 14, 15, made of such as silver, silver-platinum, which supplies power, wherein the resistance value per unit area is low and a large heat generation phenomenon by energization is hard to occur are formed on one side of a long flat plate-shaped insulating substrate 11 having a high thermal conductivity such as aluminum nitride. An overcoat layer 18 is formed on the heating resistors 121, 122 to protect electrically, mechanically, chemically with for example glass covering them. In the other side of the insulating substrate 11 where the heating resistors 121, 122 are formed, a filler is contained in imide resins such as polyimide, polyisoimide, polyamide-imide, and the content of this filler gradually decreases from the insulating substrate 11 to the surface, to form a resin coating layer 21 which surface is a sliding plane. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a thin sheet heater that is used by being mounted on small equipment such as information equipment, home appliances, and manufacturing equipment, a heating device such as a printer, a copying machine, and a facsimile machine equipped with the sheet heater, and the heating device. The present invention relates to an image processing apparatus using the.

In a conventional ceramic heater, it is known that a surface opposite to a surface on which a heating resistor of a long flat insulating substrate having high thermal conductivity such as aluminum nitride is formed is a sliding surface. (For example, Patent Document 1)
JP 2000-29334 A

  In the technique of Patent Document 1 described above, glass or fluorine resin of 20 μm or less is used for the sliding surface resin film layer in terms of durability and slidability. When the resin film layer is thin with resin, there is a problem that the resin film layer is worn and deteriorated by sliding operation, and when it is thick, heat conduction is poor and good toner fixing property cannot be obtained. In addition, when a filler is contained to such an extent that the heat conduction characteristics are effective, there is a problem that the surface of the resin film layer becomes rough and the slidability is hindered.

  An object of the present invention is to provide a ceramic heater and a heating apparatus using the same, which can obtain good fixability without impeding slidability and improve the durability of the apparatus.

  In order to solve the above-described problems, a ceramic heater according to the present invention includes a long flat plate-like insulating substrate having high thermal conductivity such as aluminum nitride, a heating resistor formed on one surface of the insulating substrate, and the heat generation. A power supply electrode portion formed to supply power to the resistor, an overcoat layer disposed to cover the heating resistor, and a filler on the back surface of the insulating substrate on which the heating resistor is formed And an imide-based resin film layer formed so as to be different from the vicinity of the insulating substrate surface so that the filler density is lower.

  According to the present invention, even when a filler is contained, since the filler content on the surface of the resin film layer is small, the surface of the resin film layer is in a smooth state, and slidability can be improved. Since the filler is contained, thermal conductivity can also be achieved.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
1 is a block diagram for explaining an embodiment of the ceramic heater of the present invention, FIG. 2 is a rear view of FIG. 1, and FIG. 3 is a sectional view taken along line xx ′ of FIG.

  In FIG. 1, reference numeral 11 denotes a highly heat conductive strip-shaped insulating substrate made of a heat-resistant, electrically insulating material such as a highly rigid ceramic having electrical insulating properties such as aluminum oxide, aluminum nitride, and silicon nitride. Reference numerals 121 and 122 denote silver-based materials such as silver-palladium formed in parallel along the longitudinal direction on the surface side of the insulating substrate 11, and resistor pastes such as ruthenium-based and carbon-based materials, which are baked at a high temperature. A heating element 13 in the form of a thick film having a resistance value of 13 is a connecting part formed by firing a silver-based conductor paste in which a part of one end of each of the heating resistors 121 and 122 is layered. Reference numeral 14 denotes a power feeding electrode made of a good conductor film mainly composed of an Ag / Pd alloy or the like in which the other end of the heating resistor 121 is formed as a multilayer. It is an electrode for electric power feeding which consists of a good conductor film | membrane which mainly has etc. Reference numerals 16 and 17 denote electrodes 14 and 15 and heating resistors 121 and 122, which are connection parts integrally formed by firing the same material as the connection part 13 in the same manner. On the heating resistors 121 and 122 and the connection portions 13, 16, and 17 that leave the electrodes 14 and 15, an overcoat layer 18 that is electrically, mechanically, and chemically protected is formed. .

  2 in FIG. 2 showing the back surface state of the insulating substrate 11 in FIG. 1 is a resin film layer. The resin film layer 21 is formed by adding a filler to an imide-based resin such as polyimide, polyisoimide, or polyamideimide, almost on the front surface of the insulating substrate 11. As the filler material, silicon, aluminum, boron, or a nitride or oxide obtained by mixing them can be considered.

  As shown in FIG. 3, the resin film layer 21 is formed so that the filler density on the surface side of the resin film layer 21 is lower than that in the vicinity of the surface of the insulating substrate 11. That is, it is in a so-called gradation state in which the filler content is gradually increased from the insulating substrate 11 side to the surface side.

  By comprising in this way, even when a filler is contained, since the content of the filler on the surface of the resin film layer is small, the surface of the resin film layer 21 is in a smooth state to improve the slidability. In addition, since the filler is contained, thermal conductivity can be achieved.

  FIG. 4 is a cross-sectional view corresponding to FIG. 3 of the above embodiment for explaining another embodiment of the ceramic heater of the present invention. In this embodiment, a plurality of resin coating layers 41a to 41d are formed so that the filler density gradually decreases as the filler of the resin film layer 41 is moved to the surface side as compared to the surface side of the insulating substrate 11. That is, the filler content of the coating layers 41a to 41d from the insulating substrate 11 side to the surface side has a relationship of 41a> 41b> 41c> 41d.

  As described above, also in this embodiment, since the filler content is gradually reduced toward the surface of the resin film layer 21, the surface of the resin film layer 21 is in a smooth state, and the slidability is improved. In addition, thermal conductivity can be achieved.

  Next, another embodiment of the ceramic heater according to the present invention will be described. In this embodiment, the filler material and filler particle size of the resin film layer are limited. That is, the filler material was a nitride or oxide of silicon, aluminum, boron, or a mixture thereof, and the filler particle size was 1/3 or less of the resin film layer.

  For example, if the resin film layer thickness is 5 to 15 μm, the filler particle size is 1/3 or less. If the resin film layer is too thin, a density distribution in the thickness direction cannot be obtained. If the resin film layer is too thick, defects such as bulges are likely to occur in specific portions of the formed resin film layer. However, when the filler particle size is 1/3 or less of the resin film layer, more uniform film formation can be realized, and the slidability of the resin film layer surface can be improved.

  Next, an embodiment of the heating device of the present invention when the ceramic heater described above is mounted on the heating device 200 will be described with reference to FIG. The heater 100 in the figure is the ceramic heater described with reference to FIGS. 1 to 3, and the same portions are denoted by the same reference numerals and description thereof is omitted.

  In FIG. 5, reference numeral 201 denotes a pressure roller which is rotated by a rotating shaft 202, and a heat resistant elastic material such as a silicone rubber layer 203 is fitted on the surface of the pressure roller. The heater 100 is mounted in parallel in a base (not shown) so as to face the rotating shaft 202 of the pressure roller 201.

  Around the heater 100, an endless roll-shaped fixing film 204 made of a heat-resistant sheet such as polyimide resin is circulated, and is opposite to the insulating substrate 11 on which the heating resistors 121 and 122 are formed. The surface of the resin film layer 21 is in elastic contact with the silicone rubber layer 203 of the pressure roller 201 through the fixing film 204.

  Further, the thermistor 205 is slidably disposed on the silicone rubber layer 203. The thermistor 205 is energized by, for example, the circuit configuration shown in FIG. That is, when the commercial power supply 61 is energized to the electrodes 14 and 15 of the ceramic heater 100 via the solid state relay 63 connected to the control terminal of the temperature control circuit 62, the current is supplied to the heating resistors 121 and 122 connected in series. Flows and generates heat. Due to the heat generated by the heating resistors 121 and 122, the temperature of the insulating substrate 11 also rises. This heat is transmitted to the temperature sensitive parts of the silicone rubber layer 203 and the thermistor 205 via the fixing film 204, and changes the resistance value of the temperature sensitive part. A change in the resistance value of the thermistor 205 is output via a wiring conductor formed on the back side of the insulating substrate 11, and this is input to the temperature control circuit 62 to determine whether the temperature is at the set temperature. When the temperature is lower than the set temperature, an ON signal is output to the solid state relay 63, and when the temperature is higher than the set temperature, an OFF signal is output to the solid state relay 63.

  In this way, by controlling the power applied to the heating resistors 121 and 122, the temperature of the heating resistors 121 and 122 can be adjusted. Although the temperature control circuit 62 has been described with respect to the on / off control of the solid state relay 63, temperature control by a pulse width modulation control method or the like may be used.

  In the ceramic heater 100, when power is supplied to the electrodes 13 and 14, current flows through the heating resistors 121 and 122, respectively, and the heating resistors 121 and 122 exhibit a substantially uniform heating temperature distribution in the longitudinal direction. Become. In this embodiment, for example, when the resistance values of the heating resistors 121 and 122 are set to 25Ω and a voltage of 100 V is applied, a current of 4 A flows and a heating value of 400 W can be obtained.

  Normally, as described above, the thermistor 205 provided on the back side of the substrate 11 detects the temperature of the ceramic heater 100 and controls the solid state relay 63 on / off through the temperature control circuit 62 to control it to a predetermined temperature. .

  In the heating apparatus 200 shown in FIG. 5 again, the heater 100 is energized through a connector (not shown) in which the phosphor bronze plate or the like in contact with the electrodes 14 and 15 is subjected to silver plating and is given elasticity, and is generated by the heating resistors 121 and 122. Heat is transferred to the insulating substrate 11 and the resin film layer 21, and the toner image T 1 is first transferred between the surface of the fixing film 204 provided on the resin film layer 21 and the silicone rubber layer 203 via the fixing film 204. And at least its surface part greatly exceeds the melting point and is completely softened and melted. Thereafter, on the paper discharge side of the pressure roller 201, the copy paper P is separated from the heater 100, the toner image T2 is naturally radiated and cooled and solidified again, and the fixing film 204 is also separated from the copy paper P.

  As described above, the toner image T1 is once completely softened and melted and then cooled again on the paper discharge side of the pressure roller 201, so that the condensing force of the toner image T2 is very large.

  In the heating device 200, the use of the resin film layer 21 having a filler content that decreases with distance from the insulating substrate 11 of the heater 100 prevents the slidability with the fixing film from being hindered and provides good fixing properties. In addition, the durability can be improved.

  Next, with reference to FIG. 7, an image forming apparatus according to the present invention will be described, taking as an example a copier equipped with a fixing heater according to the present invention and a fixing device using the fixing heater. In the figure, the part of the fixing device 200 is the same as described above, and the same reference numerals are given to the same parts, and the description thereof is omitted.

  In FIG. 7, reference numeral 301 denotes a casing of the copying machine 300, and 302 an original placing table made of a transparent member such as glass provided on the upper surface of the casing 301, which scans the original P <b> 1 by reciprocating in the arrow Y direction.

  An illuminating device 302 including a light irradiation lamp and a reflecting mirror is provided in the upper direction in the housing 301, and a reflected light source from the document P1 irradiated by the illuminating device 302 is a short focus small diameter imaging element. A slit exposure is performed on the photosensitive drum 304 by the array 303. The photosensitive drum 304 rotates in the direction of the arrow.

  Reference numeral 305 denotes a charger that uniformly charges, for example, a photosensitive drum 304 coated with a zinc oxide photosensitive layer or an organic semiconductor photosensitive layer. An electrostatic image subjected to image exposure by the imaging element array 303 is formed on the photosensitive drum 304 charged by the charger 305. This electrostatic image is visualized using toner made of a resin that softens and melts when heated by the developing device 306.

  The copy paper P stored in the cassette 307 is rotated by a pair of conveying rollers 309 that are rotated in pressure contact with each other in synchronization with the feeding roller 308 and the image on the photosensitive drum 304. Sent to the top. The toner image formed on the photosensitive drum 304 is transferred onto the copy paper P by the transfer discharger 310.

  Thereafter, the paper P that is separated from the photosensitive drum 304 is guided to the fixing device 200 by the conveyance guide 311 and subjected to a heat fixing process, and then is discharged into the tray 312. After the toner image is transferred, residual toner on the photosensitive drum 304 is removed using a cleaner 313.

  The fixing device 200 is longer in the direction orthogonal to the moving direction of the copy paper P than the effective length corresponding to the width (length) of the maximum size paper that can be copied by the copier 300, that is, longer than the width (length) of the maximum size paper. A pressure roller 201 of the fixing heater 100 is provided by extending the heating resistors 121 and 122.

  Then, the unfixed toner image T1 on the paper P sent between the fixing heater 100 and the pressure roller 201 is melted by receiving heat from the heating resistors 121 and 122, and characters and alphanumeric characters on the copy paper P surface. A copy image such as a symbol or a drawing is displayed.

  In this embodiment, it is possible to realize a copying machine 300 using a fixing device 200 using a ceramic heater that can prevent the hindrance to sliding with the fixing film and obtain good fixing properties and improve durability.

  The present invention is not limited to the embodiment described above. For example, the overcoat material needs to be changed depending on the material of the fixing film and other conditions, but it cannot be specified. If the fixing film is a resin, the overcoat layer is glass, and if the fixing film is a metal, the overcoat layer is It is desirable to combine. This resin includes materials that are generally excellent in slidability, such as polyamide (PA), polyacetal (POM), polytetrafluoroethylene (PTFE), polyphenylene sulfide, elastomer, polyolefin, fluorine, etc. Any of these may be used, but PI (polyimide) and PAI (polyamideimide), which are rich in elasticity from heat resistance, are preferred, but if the hardness is too low, the resin film will be scraped off, A hardness of 3H or higher is necessary.

  Moreover, although the heating resistor is configured to be folded back twice for convenience, the heating resistor configuration is not particularly limited.

  Ceramic heaters are used for fixing image forming devices such as copiers, but are not limited to this, and are installed in household electrical products, precision instruments for business use and experiments, and chemical reaction equipment. It can also be used as a heat source for heating and heat insulation.

  Next, in addition to the technical idea described in the claims, the technical idea grasped by the above-described embodiment will be described below together with the effects thereof.

  (1) A long flat plate-like insulating substrate having high thermal conductivity such as aluminum nitride, a heating resistor formed on one surface of the insulating substrate, and a feeding electrode unit formed at both ends of the heating resistor A protective layer disposed to cover the heating resistor, a filler formed on a surface facing the heating resistor and the insulating substrate surface, and the filler density compared to the vicinity of the insulating substrate surface An imide-based resin film layer having a different filler density in the thickness direction so that the surface portion of the film is lower, and the filler material is one of silicon, aluminum, boron, or a mixed nitride A ceramic heater, wherein the maximum particle size is 1/3 or less of the resin film layer thickness.

  Thus, when the maximum particle size of the filler is 1/3 or less of the resin film layer thickness, the interval between adjacent fillers becomes appropriate, and a good heat conduction effect can be obtained. Moreover, the influence of unevenness on the surface of the resin film layer is suppressed, and a heater having high slidability can be realized.

  (2) A long flat plate-like insulating substrate having high thermal conductivity such as aluminum nitride, a heating resistor formed on one surface of the insulating substrate, and a feeding electrode portion formed at both ends of the heating resistor A protective layer disposed to cover the heating resistor, a filler formed on a surface facing the heating resistor and the insulating substrate surface, and the filler density compared to the vicinity of the insulating substrate surface An imide-based resin film layer having a different density of the filler in the thickness direction so that the film surface portion is lower, and the film thickness of the imide-based resin film layer is 5 to 15 μm. Ceramic heater.

  Thus, by setting the resin film layer thickness of the imide-based resin to 5 to 15 μm, it is possible to obtain a desired density distribution in the thickness direction, and it is possible to prevent the occurrence of defects such as swelling of specific portions due to being too thick. It becomes.

The block diagram for demonstrating one Embodiment regarding the ceramic heater of this invention. The block diagram of the back surface of FIG. X-x 'sectional drawing of FIG. The block diagram for demonstrating other embodiment regarding the ceramic heater of this invention. Explanatory drawing for demonstrating one Embodiment regarding the heating apparatus of this invention. The circuit block diagram for demonstrating the temperature adjustment used for FIG. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory diagram for explaining an embodiment of an image forming apparatus according to the present invention;

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Insulation board | substrate 121,122 Heat generating resistor 13 Connection part 14,15 Electrode 16,17 Connection part 18 Overcoat layer 21,41,41a-41d Resin film layer 100 Ceramic heater 200 Heating apparatus 300 Image forming apparatus

Claims (3)

A long plate-like insulating substrate having high thermal conductivity such as aluminum nitride;
A heating resistor formed on one surface of the insulating substrate;
A feeding electrode portion formed to supply power to the heating resistor;
An overcoat layer disposed so as to cover the heating resistor;
An imide-based resin film layer formed on the back surface of the insulating substrate on which the heat generating resistor is formed, containing a filler, and the filler density is changed so as to become lower as it is farther from the vicinity of the insulating substrate surface; A ceramic heater comprising: A heating roller;
The heater according to claim 1, wherein a heating resistor disposed to face the heating roller is pressed.
A heating device comprising a fixing film movably provided between the heater and the pressure roller. Forming means for attaching a toner to an electrostatic latent image formed on a medium and transferring the toner to a sheet to form a predetermined image;
3. A fixing device according to claim 2, wherein the toner is fixed by passing a sheet on which an image is formed through a fixing film through a fixing film while being pressed against the fixing heater. Image forming apparatus.

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