JP2007157456A - Ceramic heater, heating device, image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize quick heat generation of a heating element pattern in a length direction of an insulating substrate formed on a top face of the substrate, and to make a temperature distribution uniform. <P>SOLUTION: Wiring patterns 14, 15 are formed in parallel on a long-size and flat insulation substrate 11 formed of a ceramic, glass ceramic or a heat-resistant complex material such as alumina. Electrodes 12, 13 for supplying power to the wiring patterns 14, 15 are formed at the same end of each pattern formed. Wide heating element paste of a silver-group material beginning with Ag (silver), and Pd (palladium), a ruthenium system, a carbon system or the like is screen-printed between the wiring patterns 14, 15 in a length direction of the insulation substrate 11, baked at high temperature to form a strip resistive heating element 16 with a given resistance value and a thickness of around 10 μm. The resistive heating element 16 is formed shorter as it is away from the electrodes 12, 13. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a thin ceramic 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 mounted with the ceramic heater, and the heating device. The present invention relates to an image forming apparatus.

In a conventional heater using an insulating substrate such as ceramic, a heating resistor having a positive temperature coefficient (PTC) is formed on both sides in the longitudinal direction on the insulating substrate, and one end of the heating resistor on the same side. Are provided with electrodes for power supply (for example, Patent Document 1).
Japanese Unexamined Patent Publication No. 7-94260 (page 4, FIG. 3)

  In the technique of Patent Document 1 described above, a resistance heating element is formed in the short direction of the insulating substrate, and in the case of a PTC heating resistor, the temperature coefficient of resistance (TCR: Temperature Coefficient of Resistance) is too large. Control becomes difficult. Even when a heating resistor having a small TCR is used, there is a problem that the amount of heat generation is large and the temperature distribution is inclined because electricity easily flows to the power supply electrode side.

  An object of the present invention is to obtain a uniform heat generation in the longitudinal direction and to have a quick temperature rise characteristic, and to enable accurate temperature control, a heating device using the ceramic heater, and an image using the heating device. It is to provide a processing apparatus.

  In order to solve the above-described problems, according to a first aspect of the ceramic heater of the present invention, a long flat insulating substrate formed of a heat-resistant and insulating material and along both longitudinal sides on the insulating substrate surface. First and second wiring patterns formed respectively, and first and second wirings formed at one end in the same direction as the first and second wiring patterns, respectively, to supply power to the first and second wiring patterns. The first and second wiring patterns are formed and electrically connected to each other, and the length is reduced as the distance from the first and second electrodes is increased, and the first and second wiring patterns are formed widely in the longitudinal direction of the insulating substrate. And a heating resistor.

According to a second aspect of the ceramic heater of the present invention, in the first aspect, the length of the heating resistor closest to the first and second electrodes is L1, the length of the farthest side is L2, The width of the heating resistor is W (mm), the sheet resistance value of the heating resistor is R (Ω / □), the constant A is −4.0 × 10 ⁻⁵ , and the constant B is 4.8 × 10 ^−4. When ≦ B ≦ 6.5 × 10 ⁻⁴ , the aperture ratio X from the length L1 to L2 of the heating resistor is:
L2 / L1 = 1-X
X = (A × R + B) × L1 × W
= (A x L1 x W) R + (L1 x W) B
It satisfies the following relational expression.

  According to the present invention, with the above-described configuration, a rapid temperature rise and a uniform temperature distribution in the longitudinal direction of the insulating substrate can be obtained.

Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings.
1 and 2 are diagrams for explaining a first embodiment of a ceramic heater according to the present invention. FIG. 1 is a configuration diagram, and FIG. 2 is a sectional view taken along line xx ′ of FIG.

In FIG. 1, reference numeral 11 denotes a heat-resistant, electrically insulating material having a thickness of about 0.5 mm to 1.0 mm, such as a highly rigid ceramic having an electrical insulating property such as alumina (Al ₂ O ₃ ), aluminum nitride (AlN) It is a strip-shaped insulating substrate made of a highly heat conductive flat plate. Reference numerals 12 and 13 denote power supply electrodes made of a good conductor film mainly composed of silver or the like. Reference numerals 14 and 15 denote wiring patterns formed of silver (Ag) or the like in parallel with both sides of the insulating substrate 11 in a non-contact state with one end connected to the electrodes 12 and 13, respectively. The electrode 12, the wiring pattern 14, the electrode 13, and the wiring pattern 15 are integrally formed by applying a conductive paste on the insulating substrate 11 and firing it, and are fixed to the insulating substrate 11. The opposite side wiring pattern 14 formed integrally with the electrode 12 and the opposite side of the wiring pattern 15 formed integrally with the electrode 13 are in an open state. That is, the electrodes 12 and 13 are integrally formed at one end of the wiring patterns 14 and 15 in the same direction.

  Reference numeral 16 denotes a silver-based material such as Ag (silver) / Pd (palladium) formed in parallel along the longitudinal direction of the insulating substrate 11 between the wiring patterns 14 and 15, ruthenium-based, carbon-based, and the like. A heat-generating paste such as the above is screen-printed and then fired at a high temperature to form a belt-like heating resistor having a predetermined resistance value and a film thickness of about 10 μm. The heating resistor 16 has a TCR of about ± 300 ppm / ° C. and a sheet resistance value of about 1 to 10 Ω / □.

  As shown in FIG. 2, the wiring pattern 14, the heating resistor 16, the wiring pattern 15, and the heating resistor 16 are partially stacked in the longitudinal direction. In this case, the multilayer portion has a relationship in which the heating resistor 16 is disposed on the upper side with respect to the wiring patterns 14 and 15. This relationship may be reversed.

  Further, the heating resistor 16 has a relationship of L1> L2 with the length L2 of the wiring patterns 14 and 15 on the far side compared to the length L1 of the wiring patterns 14 and 15 on the side close to the electrodes 14 and 15. . The lengths L1 to L2 are formed so as to be gradually narrowed.

  2, alumina is formed so as to cover the wiring patterns 14 and 15 and the heating resistor 16, and has a glass layer thickness of about 20 μm to 100 μm and a thermal conductivity of, for example, 2 W / m · K or more. It is an overcoat layer such as glass to which 25 to 35 wt% of an inorganic oxide filler having excellent isothermal conductivity is added. The overcoat layer 17 mechanically, chemically and electrically protects the wiring patterns 14 and 15 and the heating resistor 16.

  Here, with reference to FIG. 3, FIG. 4, the relationship of the inclination which narrows down gradually from length L1-L2 is demonstrated.

  First, FIG. 3 is a configuration diagram in which the main part of FIG. 1 is extracted. The width of the heating resistor 16 formed between the wiring patterns 12 and 13 is W and is close to the electrodes 12 and 13. This shows a state where the heat generating resistor 16 on the side is squeezed to the length L1 and the length L2 on the far side.

  FIG. 4 is an explanatory diagram for explaining a change in the resistance value of the heating resistor 16 when the lengths L1 and L2 are changed in the entire region from the length L1 to the length L2.

  3 and 4, the gradient of the temperature distribution is as follows: the width W (mm) of the heating resistor 16, the lengths L1 (mm) and L2 (mm), and the sheet resistance value R (mΩ / □) of the heating resistor 16. It will be different.

Therefore, the squeezing rate of the heating resistor 16 that is squeezed so as to gradually become shorter from the length L1 to L2 is X (%), the constant A is −4.0 × 10 ⁻⁵ , and the constant B is 4.8 × 10 6. ⁻⁴ ≦ B ≦ 6.5 × 10 ⁻⁴
L2 / L1 = 1−X
X = (A × R + B) × L1 × W
= (A x L1 x W) R + (L1 x W) B
It is represented by For example, when L1 = 2.16 mm and W = 220 mm, the lengths L1 and L2 are changed within the range of the temperature distribution shown in FIG. The length L2 is determined by the sheet resistance value R and the aperture ratio X.

  Further, (L1 × W) B represents the width when the length L1 is changed as shown in FIG. 4, and (A × L1 × W) is a heating resistor that is narrowed down from the length L1 to the length L2. 16 slopes are represented.

  As described above, the plate-like ceramic heater 100 is configured. The thickness of the overcoat layer 17 is determined in consideration of the heat transfer characteristics of the material to be selected, durability in the apparatus, and the like, and is not particularly defined.

  The ceramic heater 100 configured as described above has a short length between the wiring patterns 14 and 15 when electric power is supplied to the wiring patterns 14 and 15 formed on both sides of the insulating substrate 11 in the longitudinal direction. Since power is quickly supplied to the entire area of the heating resistor 16 to be formed, it is possible to realize rapid heat generation.

  Further, the heating resistor 16 sets the current amount at each point in the longitudinal direction of the insulating substrate 11 in the same manner by making the length of the wiring patterns 14 and 15 gradually narrow as the distance from the electrodes 12 and 13 increases. can do. Thereby, as shown in FIG. 5, a uniform temperature distribution can be realized regardless of the position near and far from the electrodes 12 and 13.

  In the ceramic heater 100, when the electrodes 12 and 13 are energized, a current flows through the heating element pattern 16, and the heating element pattern 16 exhibits a substantially uniform heating temperature distribution in the longitudinal direction. In the ceramic heater 100, silver / palladium, ruthenium oxide and inorganic oxide contained in the resistance paste serve as electrical resistance elements, and the resistance value of the heating element pattern 16 is adjusted by the ratio of silver / palladium and ruthenium oxide. In this embodiment, for example, the resistance value of the heating element pattern 16 is 25Ω, and a current of 4 A flows when a voltage of 100 V is applied, resulting in a heat generation amount of about 400 W.

  FIG. 6 is a front view for explaining a second embodiment relating to the ceramic heater of the present invention. The same components as those in FIG.

  In this embodiment, as the distance from the electrodes 12 and 13 increases, the width of the wiring patterns 13 and 14 increases in the lateral direction of the insulating substrate 11, and as the distance from the electrodes 12 and 13 increases, the heating resistor of FIG. The heating resistor 161 formed by the same method as that of the material 16 is narrowed in the short direction of the insulating substrate 11. In FIG. 6, as the distance from the electrodes 12 and 13 increases, the heating resistor 161 is also narrowed in the short direction of the insulating substrate 11.

  Even in the case of this embodiment, since power is quickly supplied to the entire heating resistor 161, quick heat generation can be obtained, and a uniform temperature distribution can be realized regardless of the position near and far from the electrodes 12 and 13. be able to.

  FIG. 7 is a front view for explaining a third embodiment relating to the ceramic heater of the present invention. The same components as those in FIG.

  In this embodiment, as the distance from the electrodes 12 and 13 increases, the length of the wiring patterns 14 and 15 of the heating resistor 162 formed by the same method and the same material as the heating resistor 16 in FIG. It is. At this time, the widths of the wiring patterns 14 and 15 are left as they are, and the wiring patterns 14 and 15 are also moved in the direction approaching as the heating resistor 161 is stopped.

  In this embodiment, in addition to the effects of the second embodiment, the material cost of the wiring patterns 14 and 15 can be reduced.

  FIG. 8 is a front view for explaining a fourth embodiment relating to the ceramic heater of the present invention. The same components as those in FIG.

  In this embodiment, the wiring patterns 14 and 15 are formed substantially parallel to the longitudinal direction of the insulating substrate 11, and the side farthest from the electrodes 12 and 13 that are not in contact with the wiring patterns 14 and 15 between the wiring patterns 14 and 15. A wedge-shaped wiring pattern 18 having a gradually narrower width is formed on the side closer to the wiring pattern, a resistance heating element 163 is formed between the wiring pattern 18 and the wiring pattern 14, and a resistance heating element 164 is formed between the wiring pattern 18 and the wiring pattern 15. Is.

  The heating resistors 163 and 164 in this embodiment are gradually connected to the wiring patterns of the heating resistors 163 and 164 formed by the same method as the material of the heating resistor 16 in FIG. 14 and 15 are made shorter and equivalently formed in the same manner as the heating resistor 16 in FIG.

  Therefore, in this embodiment, it is possible to realize quick heat generation in the longitudinal direction of the insulating substrate and uniform temperature distribution.

  FIG. 9 is a front view for explaining a fifth embodiment relating to the ceramic heater of the present invention. The same components as those in FIG.

  In this embodiment, the wiring patterns 14 and 15 are formed substantially parallel to the longitudinal direction of the insulating substrate 11, and are farthest from the electrodes 12 and 13 between the wiring patterns 14 and 15 in a non-contact state with the wiring patterns 14 and 15. Wiring patterns 181, 182 and 183 having different lengths are formed on the side closer to the side. A heating resistor 165 is formed between the wiring patterns 14 and 181, between the wiring patterns 181 and 183, and between the wiring patterns 14 and 183. Further, a heating resistor 166 is formed between the wiring patterns 183 and 182, between the wiring patterns 182 and 15, and between the wiring patterns 183 and 15.

  In this embodiment, the heating resistors 165 and 166 from the wiring pattern 183 at the end closest to the electrodes 12 and 13 to the end of the wiring pattern 182 closest to the electrodes 12 and 13 and the wiring pattern 182 closest to the electrodes 12 and 13 are used. Heating element 165, 166 from the end of the wiring pattern 181 to the end of the wiring pattern 181 closest to the electrodes 12, 13 and the end of the wiring pattern 182 farthest from the end of the wiring pattern 181 closest to the electrodes 12, 13 to the electrodes 12, 13 The combined resistance values between the wiring patterns 14 and 15 are different from each other by the heating resistors 165 and 166.

  In the case of this embodiment, the wiring patterns 14 and 15 are moved away from the electrodes 12 and 13 to the position where the wiring patterns 182 are located, the positions where the wiring patterns 182 and 183 are located, and the positions where the wiring patterns 182, 183 and 181 are located. The heating resistances 165 and 166 are gradually reduced in the combined resistance value therebetween. Therefore, it is possible to realize rapid heat generation in the longitudinal direction of the insulating substrate 11 and to make the temperature distribution uniform.

  In this case, there is a section in which the lengths of the synthetic heating resistors 165 and 166 are the same in the longitudinal direction of the insulating substrate 11, and the temperature distribution is slightly inhomogeneous in this section. In order to solve this problem, the number of wiring patterns having different lengths between the wiring patterns 14 and 15 may be increased.

  Next, with reference to FIG. 10, an embodiment relating to the heating device of the present invention when the above-described ceramic heater is mounted on the fixing device 200 will be described. In the figure, the ceramic heater 100 is the same as that shown in FIGS.

  In FIG. 10, 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 thereof. The ceramic heater 100 is juxtaposed with the rotating shaft 202 of the pressure roller 201 and attached to a base (not shown).

  An endless roll-shaped fixing film 204 made of a heat-resistant sheet made of polyimide resin or the like is wound around the base including the ceramic heater 100 so as to be circulated and insulated through resistance heating elements 161-166. The surface of the overcoat layer 17 directly above the substrate 11 is in elastic contact with the silicone rubber layer 203 of the pressure roller 201 via the fixing film 204.

  In the fixing device 200, the ceramic heater 100 is energized through a connector (not shown) made of a phosphor bronze plate or the like that is in contact with the electrodes 12 and 13, and generates heat on the overcoat layer 17 of the resistance heating elements 161 to 166 that generate heat. The toner image T1 is first heated and melted by the ceramic heater 100 via the fixing film 204 between the surface of the fixing film 204 provided and the silicone rubber layer 203, and at least the surface portion 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 ceramic 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. Therefore, the condensing force of the toner image T2 is very large.

  In the fixing device 200, for example, the ceramic heater 100 having the overcoat layer 17 applied to the upper surface and the side surface along the longitudinal direction of the alumina insulating substrate 11 shown in FIG. Further, even if the ring-shaped fixing film 204 wound around the base including the ceramic heater 100 is in sliding contact with the peripheral surface portion along the longitudinal direction of the insulating substrate 11, the fixing film 204 is scratched. Can be prevented.

  Next, with reference to FIG. 11, a description will be given of an embodiment of the image forming apparatus of the present invention, taking as an example a copying machine equipped with a ceramic heater according to the present invention and a heating device using the ceramic heater. In the figure, the part of the heating 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. 11, 301 is a casing of the copying machine 300, 302 is a document placing table made of a transparent member such as glass provided on the upper surface of the casing 301, and reciprocates in the direction of arrow Y to scan the document Po.

  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 original Po 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 heating device 200 by the conveyance guide 311, and is discharged into the tray 312 after being subjected to heat fixing processing. Note that the residual toner on the photosensitive drum 304 is removed by the cleaner 313 after the toner image is transferred.

  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 format paper that can be copied by the copier 300, that is, longer than the width (length) of the maximum format paper. The pressure roller 201 of the ceramic heater 100 is provided by extending the resistance heating elements 161 to 166.

  Then, the unfixed toner image T1 on the paper P sent between the ceramic heater 100 and the pressure roller 201 is melted by receiving heat from the resistance heating elements 161 to 166 and is written on the surface of the copy paper P. Make a copy of numbers, symbols, drawings, etc. appear.

  Such a copying machine 300 can achieve the same effect as the contents described in the heating device 200, that is, in the copying machine or the like, it is possible to prevent premature deterioration of parts such as a fixing film or damage of copying paper. Become.

  The present invention is not limited to the above-described embodiments. For example, the overcoat material must be changed depending on the material of the opposite film and other conditions, so it cannot be specified. However, if the film is a resin, the overcoat layer is a glass, and if the film is a metal, the overcoat layer is a combination of resins. Is desirable. This resin includes materials that are generally excellent in slidability, polyamide (PA), polyacetal (POM), polytetrafluoroethylene (PTFE), polyphenylene sulfide, elastomer, polyolefin, fluorine, etc. Any of these may be used, but imides such as PI (polyimide) and PAI (polyamideimide), which are heat-resistant and rich in elasticity, are preferred, but if the hardness is too low, the resin coating will be scraped off. Hardness of 3H or higher is necessary.

  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. Thus, it can also be used as a heat source for heating and heat insulation.

The block diagram for demonstrating 1st Embodiment of the ceramic heater of this invention. X-x 'sectional drawing of FIG. The block diagram which extracted and showed the principal part of FIG. Explanatory drawing explaining the change of the resistance value of a heating resistor at the time of changing the length of the heating resistor of the ceramic heater of this invention. Explanatory drawing for demonstrating the effect of this invention. The block diagram for demonstrating 2nd Embodiment of the ceramic heater of this invention. The block diagram for demonstrating 3rd Embodiment of the ceramic heater of this invention. The block diagram for demonstrating 4th Embodiment of the ceramic heater of this invention. The B block diagram for demonstrating 5th Embodiment of the ceramic heater of this invention. Schematic for demonstrating one Embodiment regarding the heating apparatus of this invention. BRIEF DESCRIPTION OF THE DRAWINGS Schematic for demonstrating one Embodiment regarding the image forming apparatus of this invention.

Explanation of symbols

11 Insulating substrate 12, 13 Electrodes 14, 15, 18, 181 to 183 Wiring pattern 16, 161 to 166 Heating resistor 17 Overcoat layer 100 Ceramic heater 200 Fixing device 300 Copying machine

Claims (4)

A long flat insulating substrate formed of a heat-resistant and insulating material;
First and second wiring patterns respectively formed along both longitudinal sides on the insulating substrate surface;
First and second electrodes formed at one end in the same direction as the first and second wiring patterns, respectively, and supplying power to the first and second wiring patterns;
A heating resistor formed between and electrically connected to the first and second wiring patterns, having a shorter length as the distance from the first and second electrodes increases, and widely formed in the longitudinal direction of the insulating substrate; A ceramic heater comprising: The length of the heating resistor closest to the first and second electrodes is L1, the length of the farthest side is L2, the width of the heating resistor is W (mm), and the sheet of the heating resistor When the resistance value is R (Ω / □), the constant A is −4.0 × 10 ⁻⁵ , and the constant B is 4.8 × 10 ⁻⁴ ≦ B ≦ 6.5 × 10 ⁻⁴ , the heating resistance The aperture ratio X from the body length L1 to L2 is
L2 / L1 = 1-X
X = (A × R + B) × L1 × W
= (A x L1 x W) R + (L1 x W) B
The ceramic heater according to claim 1, wherein the following relational expression is satisfied. A heating roller;
The ceramic heater according to any one of claims 1 to 3, wherein a resistance heating element disposed to face the heating roller is pressed.
A heating device comprising a fixing film movably provided between the ceramic heater and the pressure roller. 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;
5. An image forming apparatus comprising: a fixing device according to claim 4, wherein the toner is fixed by passing a sheet on which an image is formed through a pressure roller through a fixing film while being pressed against a ceramic heater. apparatus.

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