JP2006012444A - Ceramic heater, heating apparatus, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize a ceramic heater capable of attaining a temperature distribution further uniform in the longitudinal direction of the heat generated by serially connected resistance heaters of PTC. <P>SOLUTION: The resistance heaters 16 and 17 having positive temperature coefficients are formed with a predetermined longitudinal space on a ceramic-made lengthy flat substrate 11. One short-hand directional end of the resistance heater 16 is connected to a wiring pattern 14 in an electrically connected state on the substrate 11. One short-hand directional end of the resistance heater 17 is connected to a wiring pattern 15 in an electrically connected state on the substrate. The other short-hand directional end of the resistance heater 16 is electrically connected to a wiring pattern 18 on the substrate 11. The other short-hand directional end of the resistance heater 17 is electrically connected to a wiring pattern 19 on the substrate 11. The longitudinal other ends of the wiring patterns 14 and 15 one-side ends of which are opened are connected to an electrode 12. The longitudinal other ends of the wiring patterns 18 and 19 one-side ends of which are opened are electrically connected to an electrode 13. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a thin sheet ceramic heater used for information equipment, home appliances, manufacturing facilities, etc., a heating device such as a printer, a copying machine, a facsimile machine, etc. mounted with the ceramic heater, and an image processing device using the heating device. .

In a conventional heater using a ceramic substrate, a resistance heating element having a plurality of positive temperature coefficients (PTCs) is arranged in parallel between electrodes formed along both longitudinal sides of a long substrate. In order to reduce the temperature change due to different regions of the resistance heating element, power is supplied from different ends of the electrodes formed on both sides in the longitudinal direction of the substrate. (For example, Patent Document 1)
JP-A-5-29067 (3rd and 4th pages, FIGS. 1 to 3)

  The technique of the above-mentioned patent document 1 reduces the temperature change in a different place by making the electric power supply concerning a resistance heating element into the same conditions. However, there is a problem in that the temperature between the heating resistors connected in parallel is slightly low, and temperature unevenness occurs in the heat generated by the resistance heating device in the longitudinal direction of the substrate.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a ceramic heater capable of obtaining a uniform temperature distribution in the longitudinal direction of the heat generated by the PTC resistance heating elements connected in parallel, a heating device using the ceramic heater, and an image processing device using the heating device. Is to provide.

  In order to solve the above-described problems, a ceramic heater according to the present invention is formed by a long flat plate-like insulating substrate formed of a heat-resistant / insulating material and a predetermined interval in the longitudinal direction on the substrate surface. A first resistance heating element having a positive temperature coefficient and a first resistance heating element formed on the substrate in a state of being electrically connected to one end in a short direction of the first resistance heating element. A wiring pattern, a second wiring pattern formed on the substrate in a state of being electrically connected to one end in a short direction of the second resistance heating element, and a short direction of the first resistance heating element A third wiring pattern formed on the substrate connected to the other end of the second wiring pattern, and a fourth wiring pattern formed on the substrate connected to the other end of the second resistance heating element in the short direction. , One end of each of the first and second wiring patterns open at one end is connected to the other end in the longitudinal direction. A first electrode which is characterized in that the one end is provided with a second electrode respectively connected to the other longitudinal end of said opened third and fourth wiring pattern.

  According to this invention, it is possible to achieve a more uniform temperature distribution in the longitudinal direction while using the PTC resistance heating element.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a front view for explaining an embodiment of the ceramic heater of the present invention, and FIG. 2 is a sectional view taken along line xx ′ of FIG.
In FIG. 1, reference numeral 11 denotes a flat ceramic substrate formed of a ceramic such as alumina (Al ₂ O ₃ ) having a thickness of about 0.5 mm to 1.0 mm, a glass ceramic, or a heat resistant composite material. Reference numerals 12 and 13 denote power supply electrodes formed by fixing a good conductor film mainly composed of silver (Ag) or the like to both ends of the substrate 11. Reference numeral 14 denotes a wiring pattern extending along the longitudinal direction of the substrate 11, and reference numeral 15 denotes a wiring pattern extending along the longitudinal direction of the substrate 11 at a distance from the wiring pattern 14. Nos. 16 and 17 are printed with a PTC heating element paste in which rare earth metal oxide is mainly added to barium titanate (BaTiO ₃ ) between the wiring patterns 14 and 15 at a predetermined interval in the longitudinal direction of the substrate 11. Thereafter, the resistance heating element is formed by firing.

  One end of the resistance heating element 16 in the short direction is formed on the wiring pattern 14 in a state of being partly multilayered with the wiring pattern 14, and one end in the short direction of the resistance heating element 17 is formed on the wiring pattern 15 in part. In this state, the wiring patterns 15 are formed so as to be electrically connected to the substrate 11. Reference numerals 18 and 19 denote wiring patterns formed by the same material and process as the wiring patterns 14 and 15, for example. The wiring pattern 18 is electrically connected to the substrate 11 in a state where a part of the other end in the short direction of the resistance heating element 16 and the other end of the resistance heating element 17 in the short direction are respectively multilayered. It is formed in a connected state.

  One end in the longitudinal direction of the wiring patterns 14 and 15 is connected to the electrode 12 via a connection pattern 20 fixedly formed on the substrate 11, and the other end in the longitudinal direction is opened. One end in the longitudinal direction of the wiring patterns 18 and 19 is connected to the electrode 13 via a connection pattern 21 fixedly formed on the substrate 11, and the other end in the longitudinal direction is opened.

  22 shows resistance heating elements 16 and 17 and wiring patterns 14, 15, 18, and 19 excluding a part of the electrodes 12 and 13 and the substrate 11 as shown in FIG. 2 of the xx ′ cross section of FIG. A glassy overcoat layer having a glass layer thickness of about 20 μm to 100 μm and a thermal conductivity of, for example, 2 W / m · K or more is formed so as to cover the substrate 11 including the substrate.

  The plate-shaped ceramic heater 100 is comprised by the above structure. The thickness of the overcoat layer 22 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.

  As described above, two resistance heating elements 16 and 17 are formed in the longitudinal direction of the substrate 11 and are connected in parallel to the electrodes 12 and 13. When power is supplied to the electrodes 12 and 13, current flows through the resistance heating element 16 between the wiring patterns 14 and 18 and the resistance heating element 17 between the wiring patterns 15 and 19, respectively, and the resistance heating elements 16 and 17 generate heat. The Since the resistance heating elements 16 and 17 which are wide in the longitudinal direction of the substrate 11 are arranged between the corresponding wiring patterns 14 and 18 and 15 and 19 having a narrow interval, respectively, the resistance heating elements 16 and 17 are arranged at specific positions of the resistance heating elements 16 and 17. Even if there is an abnormality, since the width is large, it is possible to suppress the influence on heat generation as much as possible and obtain a uniform temperature distribution. In addition, since the resistance heating elements are arranged between the corresponding wiring patterns with a narrow interval, a quick rise in temperature can be obtained.

  In addition, the resistance heating elements 16 and 17 connected in parallel have a positive temperature coefficient, so that the resistance increases as the temperature rises. However, since the resistance heating elements 16 and 17 are connected in parallel, the resistance value decreases and current flows. Since it becomes difficult, the influence by a temperature difference can be suppressed and it contributes to uniform temperature distribution.

  FIG. 3 is a front view for explaining another embodiment of the ceramic heater according to the present invention, and FIG. 4 is a sectional view taken along the line y-y 'in FIG. In this embodiment, the configuration of the wiring pattern 31 in which the wiring patterns 18 and 19 are integrally formed is different from that in FIG. 1, and the same components are denoted by the same reference numerals and the description thereof is omitted.

  That is, two resistance heating elements 16 and 17 are formed in the longitudinal direction of the substrate 11 and are connected in parallel to the electrodes 12 and 13. When electric power is supplied to the electrodes 12 and 13, current flows through the resistance heating element 16 between the wiring patterns 14 and 31, and the resistance heating element 17 between the wiring patterns 15 and 31, respectively, and the resistance heating elements 16 and 17 generate heat. Is done.

  In this embodiment, since the wiring pattern 31 connected to the electrode 13 is integrated in addition to the above-described effects of the heating resistors 16 and 17 by the parallel connection, it is possible to shorten the short dimension of the substrate 11. It becomes.

  FIG. 5 is a sectional view corresponding to FIG. 4 for explaining another embodiment of the present invention. This embodiment differs from the embodiment of FIG. 3 in that the same components are the same as the resistance heating element 167 in which the resistance heating elements 16 and 17 are integrated and arranged below the wiring patterns 14, 15 and 31. This will be described with reference numerals.

  In this embodiment, since the integral heating resistor 167 is disposed between the wiring patterns 14 and 31 and 15 and 31, it can be formed under substantially the same conditions, and almost the entire surface of the wiring patterns 14, 15, and 31. Is in contact with the heat generating resistor 167, the connection conditions between the wiring patterns 14, 15, 31 and the resistance heat generating member 167 can also suppress variations due to products. In addition, the resistance values of the respective heating resistors 167 between the wiring patterns 14 and 31 and 15 and 31 which are in a parallel connection relationship are more easily set under the same conditions.

  The ceramic heater 100 having the above-described configuration is incorporated in a heating device, and is energized by, for example, a circuit configuration illustrated in FIG. That is, when the commercial power supply 51 is energized to the electrodes 12 and 13 of the ceramic heater 100 via the solid state relay 53 connected to the control terminal of the temperature control circuit 52, the current flows to the resistance heating elements 16 and 17 connected in series. Flows and generates heat. The temperature of the substrate 11 also rises due to heat generated by the resistance heating elements 16 and 17. This heat is transmitted to the temperature sensing part of the thermistor 54 attached to the back side of the substrate 11 and changes the resistance value of the temperature sensing part. A change in the resistance value of the thermistor 54 is output via a wiring conductor formed on the back side of the substrate 11 in FIG. 1, and this is input to the temperature control circuit 52 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 53, and when the temperature is higher than the set temperature, an OFF signal is output to the solid state relay 53.

  Thus, the temperature of the resistance heating elements 16 and 17 is adjusted by controlling the power applied to the resistance heating elements 16 and 17. Although the temperature control circuit 52 has been described with respect to the ON / OFF control of the solid state relay 53, temperature adjustment by a pulse width modulation control method or the like may be used.

  In the ceramic heater 100, when electric power is supplied to the electrodes 12 and 13, current flows through the resistance heating elements 16 and 17, respectively, and the resistance heating elements 16 and 17 exhibit a substantially uniform heating temperature distribution in the longitudinal direction. . In this embodiment, for example, when the resistance value of the resistance heating elements 16 and 17 is 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 54 provided on the back side of the substrate 11 detects the temperature of the ceramic heater 100 and controls the solid state relay 53 on / off through the temperature control circuit 52 to control it to a predetermined temperature. .

  Next, with reference to FIG. 7, an embodiment of the heating device of the present invention when the embodiment of the ceramic heater described above is mounted on the fixing device 200 will be described. The ceramic heater 100 in the figure is the same as that in FIGS. 1 and 2, and the same portions are denoted by the same reference numerals and description thereof is omitted.

  In FIG. 7, 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).

  Around the ceramic heater 100, an endless roll-shaped fixing film 204 made of a heat-resistant sheet such as polyimide resin is circulated so as to circulate freely, and over the substrate 11 via the resistance heating elements 16 and 17 is overlaid. The surface of the coat layer 21 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) in which a phosphor bronze plate or the like in contact with the electrodes 12 and 13 is subjected to elasticity by silver plating. 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 above and the silicone rubber layer 203, and at least the surface portion greatly exceeds the melting point and is completely softened. Melt. 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, so that the condensing force of the toner image T2 is very large.

  In the fixing device 200, since the resistance heating elements 16 and 17 connected in parallel shown in FIG. 1 have a positive temperature coefficient, the resistance increases as the temperature rises. However, the resistance value of the resistance heating elements 16 and 17 as a whole is increased. Since the current becomes smaller and current does not flow easily, the influence of the temperature difference can be suppressed, which contributes to uniform temperature distribution. As a result, fixing unevenness and defects can be improved.

  Next, with reference to FIG. 8, an image forming apparatus according to the present invention will be described, 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. 8, 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 scans the document P1 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 heating device 200 by the conveyance guide 311 and subjected to a heat fixing process, and then 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 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 16 and 17.

  The unfixed toner image T1 on the paper P sent between the ceramic heater 100 and the pressure roller 201 is melted by the heat of the resistance heating elements 16 and 17 and is printed on the surface of the copy paper P with characters and alphanumeric characters. A copy image such as a symbol or a drawing is displayed.

  Since the copying machine 300 can prevent fixing unevenness and defects in the copying machine and the like, it can contribute to prevention of waste of copying paper.

  The present invention is not limited to the above-described embodiments. For example, the overcoat layer material cannot be specified because it needs to be changed depending on the material of the opposing fixing film and other conditions. However, when the fixing film is a resin, the overcoat layer is an overcoat layer when glass or the fixing film is a metal. It is desirable to combine resins. As this resin, polyamide (PA), polyacetal (POM), polytetrafluoroethylene (PTFE), polyphenylene sulfide, elastomers, polyolefins, fluorine, etc., which are generally considered to be excellent in slidability, are used. Conceivable. Basically, any of these may be used, but imides such as PI (polyimide) and PAI (polyamideimide), which are heat-resistant and elastic, are preferred, but if the hardness is too low, the resin coating will be scraped off. Therefore, for example, a hardness of 3H or more 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 front view for demonstrating one Example regarding the ceramic heater of this invention. X-x 'sectional drawing of FIG. The circuit block diagram for demonstrating the temperature adjustment used for FIG. The front view for demonstrating the other Example regarding the ceramic heater of this invention. FIG. 5 is a cross-sectional view taken along the line y-y ′ in FIG. 4. Sectional drawing for demonstrating another Example of this invention. Explanatory drawing for demonstrating one Example regarding the heating apparatus of this invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory diagram for explaining an embodiment relating to an image forming apparatus of the present invention;

Explanation of symbols

11 Substrate 12, 13 Electrode 14, 15, 18, 19 Wiring pattern 16, 17 Resistance heating element 20, 21 Connection pattern 22 Overcoat layer 100 Ceramic heater 200 Fixing device 204 Fixing film 300 Copying machine

Claims (5)

A long plate-like insulating substrate formed of a heat-resistant and insulating material;
First and second resistance heating elements having positive temperature coefficients formed at predetermined intervals in the longitudinal direction on the substrate surface;
A first wiring pattern formed on the substrate in a state of being electrically connected to one end of the first resistance heating element in the short direction;
A second wiring pattern formed on the substrate in a state of being electrically connected to one end of the second resistance heating element in the lateral direction;
A third wiring pattern formed on the substrate connected to the other end in the short direction of the first resistance heating element;
A fourth wiring pattern formed on the substrate connected to the other end in the short direction of the second resistance heating element;
A first electrode connected to the other end in the longitudinal direction of the first and second wiring patterns with one end open;
And a second electrode connected to the other end in the longitudinal direction of the third and fourth wiring patterns, each having an open end, and a ceramic heater.   The ceramic heater according to claim 1, wherein the third and fourth wiring patterns are integrally formed.   2. The first and second resistance heating elements are integrally formed, and the first and fourth wiring patterns are formed in the integrally formed first and second resistance heating elements. Or the ceramic heater of 2. 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 apparatus comprising a fixing film movably provided between the ceramic heater and the heating 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. The fixing device according to claim 4, wherein the toner is fixed by passing the paper on which the image is formed through a fixing film through a fixing film while being pressed against a fixing heater. An image processing apparatus.

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