JP2011091006A - Ceramic heater, heating device, and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a heater from cracking by restraining quick temperature change on an end of the ceramic heater. <P>SOLUTION: Heating resistors 12, 13 are formed in parallel with a longitudinal direction of an elongated ceramic substrate 11. Electrodes 14, 15 for current conduction are connected with one ends of the heating resistors 12, 13, a connection conductor 16 is connected with the other end of the heating resistors 12, 13, and the heating resistors 12, 13 are connected in series. End heating resistors 121, 122 which are gradually widened from the heating resistor 12 at end zones S1, S2 are integrally formed on both ends of the heating resistor 12. End heating resistors 131, 132 which are gradually widened from the heating resistor 13 at the end zones S1, S2 are integrally formed on both ends of the heating resistor 13. The heating resistors, the end heating resistors, and the connection conductor are covered with an overcoat layer 17 in order to protect them. Resistance values of the end heating resistors 121, 122 located at an upstream side at the time of passing a record paper are set up to be lower in comparison with those of the end heating resistors 131, 132 in order to reduce temperature. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a thin ceramic heater used in small equipment such as information equipment, home appliances and manufacturing equipment, and a heating device such as a printer, a copier, a facsimile, a rewritable card reader / writer, and the like mounted with the heater. The present invention relates to an image forming apparatus using a heating device.

  The conventional ceramic heater uses a heating element in which the feeding electrode is concentrated on one side in the longitudinal direction, and the heating amount of this heating element is made different at the left and right ends, so that the non-feeding electrode side than the feeding electrode side end. The amount of heat generated at the end is increased. (For example, Patent Document 1)

JP 2006-91449 A

  In the technique of Patent Document 1 described above, in the non-sheet passing portion at the end portion where the recording paper does not pass through the heating body and heat is not easily taken away, the paper passing portion in the central portion where the recording paper passes and heat is easily taken away. In order to prevent adverse effects such as deformation of the peripheral parts such as the fixing film and the pressure roller at the end portion due to the high temperature and cracking of the insulating substrate, the end portion of the heating element has a smaller area than the center portion. Widely formed. In this case, when the recording paper comes off from the central portion and passes near the end portion, a new problem arises that the temperature on the recording paper end side is lowered and the fixing property is lowered.

  An object of the present invention is to provide a ceramic heater that prevents a heater from cracking by suppressing a rapid temperature rise at the end of the heater, a heating device using the heater, and an image forming apparatus using the heating device.

  In order to solve the above-described problems, a ceramic heater according to the present invention comprises a long flat insulating substrate formed of a heat-resistant / insulating material and a thick film formed of a conductive component parallel to the longitudinal direction on the insulating substrate. First and second heating resistors formed, and end heating resistors formed integrally with the same material as the heating resistors at both ends of the first and second heating resistors; Electric power is supplied to both ends of the first and second heating resistors connected in series, and an electrode formed on one end of the insulating substrate, and an overcoat layer formed on the insulating substrate leaving at least the electrode And the first heating resistor positioned on the upstream side through which a heated body that slides on the overcoat layer and is heated based on the first and second heating resistors first passes. The end heating resistor connected to Resistance, characterized in that said second heat generation resistor is to connect compared to the resistance value of the end heating resistor formed low.

  A heating device according to the present invention includes a ceramic heater according to any one of claims 1 to 4, a pressure roller that is disposed to face the ceramic heater and is rotatably supported so as to press-contact the ceramic heater, And a fixing film that is provided between the ceramic heater and the pressure roller and slides on the ceramic heater as the pressure roller rotates.

  The image forming apparatus according to the present invention also includes a forming unit that attaches toner to an electrostatic latent image formed on a medium and transfers the toner to a sheet to form a predetermined image; and a sheet on which the image is formed. 6. A heating device according to claim 5, wherein the toner is fixed by passing through the fixing film while being pressed against the heater by a pressure roller.

  According to the present invention, it is possible to prevent the heater from cracking by suppressing a rapid temperature rise at the end of the ceramic heater.

It is a block diagram for demonstrating 1st Embodiment regarding the ceramic heater of this invention. It is an expanded sectional view of the Ia-Ib line of FIG. It is the expanded sectional view seen from the arrow direction of the IIa-IIb line | wire of FIG. In FIG. 1, (a) in the heater longitudinal direction is an explanatory diagram for schematically explaining the temperature distribution on the upstream side, and (b) is a schematic diagram for explaining the temperature distribution on the downstream side. It is a block diagram for demonstrating 2nd Embodiment regarding the ceramic heater of this invention. 6 (a) to 6 (c) are enlarged cross-sectional views as seen from the directions of arrows in the lines Ia-Ib, IIa-IIb, and IIIa-IIIb in FIG. 5, respectively. In FIG. 5, (a) in the heater longitudinal direction is an explanatory diagram for schematically explaining the temperature distribution on the upstream side, and (b) is a schematic diagram for explaining the temperature distribution on the downstream side. It is a block diagram for demonstrating 3rd Embodiment regarding the ceramic heater of this invention. FIGS. 9A to 9D are enlarged cross-sectional views as seen from the respective arrow directions of the Ia-Ib, IVa-IVb, Va-Vb, and VIa-VIb lines in FIG. In FIG. 8, (a) in the heater longitudinal direction is an explanatory diagram for schematically explaining the temperature distribution on the upstream side, and (b) is a schematic diagram for explaining the temperature distribution on the downstream side. It is a block diagram for demonstrating 4th Embodiment regarding the ceramic heater of this invention. FIGS. 12A to 12D are enlarged cross-sectional views as seen from the respective arrow directions of the lines Ia-Ib, VIIa-VIIb, VIIIa-VIIIb, and VIa-VIb in FIG. In FIG. 11, (a) in the heater longitudinal direction is an explanatory diagram for schematically explaining the temperature distribution on the upstream side, and (b) is a schematic diagram for explaining the temperature distribution on the downstream side. It is a block diagram for demonstrating one Embodiment regarding the heating apparatus of this invention. 1 is a configuration diagram for explaining an embodiment of an image forming apparatus according to the present invention.

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

  1 to 4 are diagrams for explaining the configuration of the first embodiment of the ceramic heater according to the present invention. FIG. 1 is a configuration diagram, FIG. 2 is an enlarged sectional view taken along line Ia-Ib of FIG. FIG. 4 is an enlarged cross-sectional view as seen from the direction of the arrow IIa-IIb in FIG. 1, and FIG. 4 is an explanatory diagram for schematically explaining the temperature distribution in the heater longitudinal direction in FIG.

In FIG. 1, 11 is formed in a long shape with a heat-resistant and insulating material such as alumina (Al ₂ O ₃ ), aluminum nitride (AlN), silicon carbide (SiC), silicon nitride (Si ₃ N ₄ ) or the like. Insulating substrate. 12 and 13 are silver-based materials including an alloy of silver (Ag) / palladium (Pd) formed in parallel along the longitudinal direction on the surface side of the insulating substrate 11, ruthenium-based materials, carbon-based materials, etc. It is the 1st and 2nd heating resistor of the strip | belt shape which consists of a thick film which baked resistor paste at high temperature and has a predetermined resistance value.

  Longitudinal central region C of the insulating substrate 11 of the heating resistor 12 corresponds to the width of the recording paper is heated body, a paper passing area sliding the recording paper to the heating resistor 12. At this time, the heating resistor 12 is located upstream of the recording paper passage, and the heating resistor 13 is located downstream of the recording paper passage.

  Reference numerals 14 and 15 denote power supply electrodes for a good conductor film obtained by firing a silver-based conductor paste formed on the insulating substrate 11. 141 is a connection conductor having one end connected to the electrode 14, and 151 is a connection conductor having one end connected to the electrode 15.

  Both ends of the heating resistor 12 positioned on the upstream side are located at the end regions S1 and S2 of the non-sheet passing portion outside the central region C through which the recording paper passes, and the same material as the heating resistor 12 is formed on the outside. One end of each end heating resistor 121, 122 is integrally formed. The other end of the end heating resistor 121 is connected to the connection conductor 16. The end heat generating resistor 121 has a gradually wide shape linearly up to the width w1 of the portion connected to the connection conductor 16. The other end of the end heating resistor 122 is connected to the connection conductor 141. The end heating resistor 122 has a linearly wide shape up to the width w1 of the portion connected to the connection conductor 141.

  Similarly, both ends of the heating resistor 13 located on the downstream side are located at end regions S1 and S2 of the non-sheet passing portion outside the central region C through which the recording paper passes, and the heating resistor 12 and the outside are located on the outside. One end of each end heating resistor 131, 132 of the same material is integrally formed. The other end of the end heating resistor 131 is connected to the connection conductor 16. The end heat generating resistor 131 has a gradually wide shape linearly up to a width w2 narrower than the width w1 of the portion connected to the connection conductor 16. The other end of the end heating resistor 132 is connected to the connection conductor 151. The end heat generating resistor 132 has a linearly wide shape up to the width w2 of the portion connected to the connection conductor 151.

  Therefore, the areas of the end heat generating resistors 131 and 132 in the end regions S1 and S2 are smaller than the areas of the end heat generating resistors 121 and 122 in the end regions S1 and S2. In other words, the resistance values of the end heating resistors 131 and 132 are higher than the resistance values of the end heating resistors 121 and 122.

  Thereby, between the electrodes 14 and 15, the connection conductor 141, the end heating resistor 122, the heating resistor 12, the end heating resistor 121, the end conductor 16, the end heating resistor 131, the heating resistor are provided. The body 13, the end heating resistor 132, and the end conductor 151 are electrically connected in series. When power is supplied to the electrodes 14 and 15, the heating resistors 12 and 13 and the end heating resistors 121, 122, 131, and 132 generate heat.

  17 is a glass layer or polyimide layer formed by, for example, thick film printing on the heating resistors 12, 13, leaving the electrodes 14, 15, the end heating resistors 121, 122, 131, 132, and the connection conductor 16. An overcoat layer for electrical, mechanical and chemical protection.

  Here, consider the case where the electrodes 14 and 15 are energized together with FIG. The heating resistors 12 and 13 have substantially the same heat generation temperature distribution in the central region C of FIGS. 4A and 4B based on the resistance value of the width w.

  The end heating resistors 121 and 122 in the end regions S1 and S2 have a shape that gradually increases linearly to a width w1 wider than the width w of the heating resistor 12. From this, the amount of heat generated in the end regions S1, S2 gradually decreases as the width of the end heat generating resistors 121, 122 increases to w1, in the end regions S1, S2, as shown in FIG. The temperature distribution is such that the heat decreases by t1.

  The end heating resistors 131 and 132 in the end regions S1 and S2 have a shape that gradually increases linearly to a width w2 wider than the width w of the heating resistor 13. From this, the amount of heat generated in the end regions S1, S2 gradually decreases as the width of the end heat generating resistors 131, 132 increases to w2 in the end regions S1, S2, as shown in FIG. The temperature distribution is such that the heat decreases by t2.

  Here, since the width w1 is wider than the width w2 and has a low resistance value, the end heating resistors 131 and 132 are the end heating resistors 121 and 122 as the amount of temperature decrease in the end regions S1 and S2. Larger than That is, t1> t2.

  When the recording paper as the heated body is passed through the central region C of the ceramic heater configured as described above, when the recording paper passes through the heating resistor 12, the temperature of the recording paper is deprived and the heating resistance is reduced. The temperature of the body 12 decreases. At this time, since the temperature of the end heating resistors 121 and 122 is slightly lower than the temperature of the heating resistor 12, an abrupt temperature difference occurs between the heating resistor 12 and the end heating resistors 121 and 122. There will be no.

  Further, the recording paper passing through the heating resistor 13 has already been heated by the heating resistor 12, and the recording paper is less likely to be deprived of heat than when the heating resistor 12 passes, and the decrease is small. At this time, since the temperature of the end heating resistors 131 and 132 is originally lower than that of the heating resistor 13 and lower than that of the end heating elements 121 and 122, the heating resistor 13 and the end heating resistors 131, No abrupt temperature difference occurs between the terminal 132 and the terminal 132.

  Here, the temperature drop t1 of the end heating resistors 121 and 122 and the temperature drop t2 of the end heating resistors 131 and 132 have a relationship of t1> t2. As a result, when the recording paper that is not heated at all and the case where the heated recording paper passes, a change is given to the amount by which the temperature of the end heating resistor is lowered. For this reason, the temperature difference between the heating resistor and the end heating resistor due to the passage of the recording paper is eliminated as much as possible, and cracking in the vicinity of the end of the insulating substrate can be prevented.

  In this embodiment, by making the difference in temperature between the heating resistor as the end heating resistor and the sheet passing portion which is a non-sheet passing portion of the upstream side, cracking of the insulating substrate in the vicinity of the end heating resistor In addition, the temperature difference between the end heating resistor serving as the non-sheet passing portion on the downstream side and the heating resistor serving as the sheet passing portion of the recording paper heated by the upstream heating resistor is reduced. Thus, it is possible to prevent the insulating substrate from cracking near the end heating resistor. Therefore, it is possible to prevent the entire insulating substrate from being cracked due to thermal stress.

  5 to 7 are diagrams for explaining a second embodiment of the ceramic heater according to the present invention. FIG. 5 is a configuration diagram, and FIGS. 6 (a) to 6 (c) are Ia-Ib and IIa in FIG. FIG. 7 is an explanatory diagram for schematically explaining the temperature distribution in the heater longitudinal direction in FIG. 5. In this embodiment, the same components as those in the above-described embodiment are denoted by the same reference numerals, description thereof will be omitted, and the same applies to the following embodiments.

  In this embodiment, the end heating resistors 123 and 124 are gradually widened from both ends of the upstream heating resistor 12 in a curved manner, and the width is gradually curved from both ends of the downstream heating resistor 13. The configuration of the wide end heat generating resistors 133 and 134 is different from that of the first embodiment. That is, the widths of the end heating resistors 123 and 124 are gradually widened to W1, and the widths of the end heating resistors 133 and 134 are gradually widened to a width W2 narrower than the width W1. .

  FIG. 6B shows a cross-sectional view taken along the line IIIa-IIIb of the end heating resistors 123 and 124 that are gradually expanded in a curved manner. The heating resistors 12 and 13 up to the maximum widths w1 and w2 respectively connected to the connection conductor 16 have the widths w3 and w4 in the middle stage, and w3 connected to the width w1 is larger than w4 connected to the width w2. It has a wide relationship.

  As shown in FIG. 7 (a), the upstream end heating resistors 123 and 124 have a temperature drop of t1, and the downstream end heating resistors 133 and 134 have a temperature drop of t2. The upstream side has a relationship of t1> t2 because the resistance value is small and the temperature decrease is large because the area is larger than the downstream side, and this point is the same as in the first embodiment.

  In this case, since the end heating resistors 123, 124 and 133, 134 are gradually widened, the temperature distribution of the end regions S1, S2 in FIGS. As shown, the temperature drop also becomes curvilinear, the stress on the insulating substrate 11 can be relieved, and there is a further effect in preventing cracking.

  8 to 10 are diagrams for explaining a third embodiment of the ceramic heater according to the present invention. FIG. 8 is a configuration diagram, FIG. 9A is Ia-Ib in FIG. 8, and FIG. IVb, (c) is Va-Vb, (d) is an enlarged cross-sectional view as seen from each arrow direction of the VIa-VIb line, and FIG. 10 is a schematic illustration of the temperature distribution in the heater longitudinal direction in FIG. It is explanatory drawing.

  That is, the other end of the end heating resistor 125 where the heating resistors 12 and the one end is integrally connected is integrally connected with the width of the connection conductors 16 and W, the heating resistor 13 and one end integrally connected The other end of the end heating resistor 135 is integrally connected to the connection conductor 16 with a width of W. Further, the other end of the end heating resistor 126 whose one end is integrally connected to the heating resistor 12 is integrally connected with the width of the connecting conductor 141 and W, and one end is integrally connected to the heating resistor 13. The other end of the end heating resistor 135 is integrally connected to the connection conductor 151 with a width of W.

  That is, the end heating resistor 125 is formed so as to gradually increase from the width w of the heating resistor 12 to the width W of the portion connected to the connecting conductor 16 wider than this, and the end heating resistor 126 is the heating resistor. It is formed so as to gradually widen from a width w of 12 to a width W of a portion connected to the wider connection conductor 141. Similarly, the end heat generating resistor 135 is formed so as to gradually increase from the width w of the heat generating resistor 13 to the width W of the portion connected to the connecting conductor 16 wider than this, and the end heat generating resistor 136 is formed as the heat generating resistor. The body 13 is formed so as to gradually increase from the width w of the body 13 to the width W of the portion connected to the wider connection conductor 151.

  The gradually increasing base points of the end heating resistors 125 and 126 are from the end regions S1 and S2, and the gradually increasing base points of the end heating resistors 135 and 136 are located outside the end regions S1 and S2. From the end regions S3 and S4.

  Therefore, the end heating resistors 125 and 126 in the end regions S1 and S2 have a larger area than the end heating resistors 135 and 136, and the resistance values of the end heating resistors 125 and 126 are larger. It is low.

  Therefore, there is a temperature drop of t1 in the upstream end heating resistors 125 and 126, and there is a temperature drop of t2 in the downstream end heating resistors 135 and 136. The upstream side has a relationship of t1> t2 because the resistance value is small and the temperature decrease is large because the area is larger than that of the downstream side, and this point is the same as the above embodiments.

  Also in this embodiment, the temperature difference between the end heating resistor serving as the non-sheet passing portion on the upstream side and the heating resistor serving as the sheet passing portion is reduced, so that the insulating substrate is cracked near the end heating resistor. Can be prevented. Further, since the temperature at the end heating resistor without the end regions S3 and S4 facing the end regions S1 and S2 does not have a temperature difference from the vicinity of the heating resistor, the recording paper that passes through is surely provided. Fixing can be realized.

  FIGS. 11 to 13 are diagrams for explaining a fourth embodiment of the ceramic heater according to the present invention. FIG. 11 is a configuration diagram, and FIGS. 12 (a) to 12 (a) are (a) to Ia-Ib in FIG. , (B) is VIIa-VIIb, (c) is VIIIa-VIIIb, (d) is an enlarged sectional view as seen from each arrow direction of the VIa-VIb line, and FIG. 13 is a temperature distribution in the heater longitudinal direction in FIG. It is explanatory drawing for demonstrating typically.

  In this embodiment, the end heating resistors 127 and 128 are gradually widened from both ends of the upstream heating resistor 12 in a curved manner, and the width is gradually curved from both ends of the downstream heating resistor 13. The configuration of the wide end heating resistors 137 and 138 is different from that of the first embodiment. That is, as shown in FIG. 12A, the end heating resistors 127 and 128 are gradually expanded in a curve from the width w to the width W of the heating resistor 12, and the end heating resistors 137 and 138 are heated. The resistor 13 is gradually expanded from the width w to the width W in a curved manner.

  Figure 12 (d), the width of the end portion heating resistors 127 and 128 are connected to the connecting conductor 16 to the connecting conductor 141 end connected largest W, and the connection conductor 16 and the connection conductor 151 The width of the heating resistors 137 and 138 is the maximum W. Further, as shown in FIG. 12B, the width w of the end heating resistors 127, 128 and 137, 138 in the middle stage is narrower than w8 as shown in FIG. 12B. As shown, the width w10 is narrower than the width w9.

  The end heating resistors 127 and 128 in the end regions S1 and S2 have smaller resistance values than the end heating resistors 137 and 138 in the end regions S3 and S4. As a result, as shown in FIG. 13A, there is a temperature drop of t1 at the upstream end heating resistors 127 and 128, and a temperature drop of t2 at the downstream end heating resistors 137 and 138. . The upstream side has a relationship of t1> t2 because the resistance value is small and the temperature decrease is large because the area is larger than the downstream side, and this point is the same as in the third embodiment.

  In this case, since the end heating resistors 127, 128 and 137, 138 are formed so as to be gradually curved, the temperature distribution of the end regions S1, S2 in FIGS. 13A and 13B is shown. As described above, the temperature drop is also curvilinear, the stress on the insulating substrate 11 can be relieved, and the effect of preventing cracking is further improved.

  Next, an embodiment relating to the heating device of the present invention in the case where the above-described ceramic heater is mounted on the heating device 200 will be described with reference to the configuration diagram shown in the cross section of FIG. Reference numeral 100 in the figure denotes the ceramic heater described with reference to FIGS. 1 to 4, and the same portions are denoted by the same reference numerals and description thereof is omitted.

  In FIG. 14, reference numeral 201 denotes a stainless steel that adheres the ceramic heater 100 to the bottom of the support 202, supplies an AC voltage to the ceramic heater 100, and moves while being pressed and heated to the overcoat layer 17 of the heated ceramic heater 100. It is a cylindrical fixing film in which a heat-resistant sheet such as polyimide resin is rolled and wound in a circulating manner. 203 is a pressure roller heat-resistant elastic material in which, for example, silicone rubber layer 204 are fitted on the surface, juxtaposed ceramic heater 100, the fixing film 201 opposite to the rotation shaft 205 of the pressure roller 203 And it is attached in the base which is not illustrated. The pressure roller 203 is brought into pressure contact with the fixing film 201 based on a means (not shown) to form a nip portion, and is rotated in the direction of the arrow during operation.

  In this case, between the fixing film 201 surface and the silicone rubber layer 204 disposed on the overcoat layer 17 is heated and melted by the ceramic heater 100 via a toner image To1 is first fixing film 201, at least a surface portion It greatly exceeds the melting point and completely softens and melts. Thereafter, on the paper discharge side of the pressure roller 203, the copy paper P is separated from the ceramic heater 100, the toner image To2 is naturally radiated to be cooled and solidified again, and the fixing film 201 is also separated from the copy paper P.

  In this embodiment, since the temperature of the end region of the downstream heating resistor is slightly lower than the end region of the heating resistor downstream of the ceramic heater, the upstream side of the recording paper before heating is The temperature difference with the end region due to the temperature drop of the heating resistor was reduced. As a result, cracking of the ceramic heater can be prevented and heating defects can be eliminated.

  Next, with reference to FIG. 15, an embodiment relating to an image forming apparatus of the present invention will be described, taking as an example a copying machine equipped with the heating device 200 of the present invention. 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. 15, reference numeral 301 denotes a casing of the copying machine 300, and 302 an original placement 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 heating 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 heating device 200 has an effective length according to the width (length) of the maximum size paper that can be copied by the copying machine 300 in the direction orthogonal to the moving direction of the copy paper P, that is, the width (length) of the maximum size paper. A ceramic heater 100 having a long heating resistor is provided in a state of being pressed by a silicone rubber layer 204 attached to the outer periphery of the pressure roller 203.

  The unfixed toner image T1 on the paper P sent between the ceramic heater 100 and the pressure roller 203 is melted by receiving heat from the heating resistors 12 and 13, 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, an image forming apparatus having excellent fixability is realized by using a heating device that can prevent cracking of an insulating substrate based on a temperature difference that occurs when recording paper passes through a heating resistor of a ceramic heater. Can do.

  The use of the ceramic heater, but the fixing of an image forming apparatus such as a copying machine, not limited thereto, attached to the device for precision instruments and chemical reactions of appliances for home, or commercial experiments It can also be used as a heat source for heating and heat insulation.

11 Insulating substrate 12, 13 Heating resistors 121-128, 131-138 End heating resistors 14, 15 Electrodes 141, 151, 16 Connecting conductor 17 Overcoat layer C Central region S1-S4 End region 100 Ceramic heater 200 Heating Apparatus 201 Fixing film 203 Pressure roller 300 Copying machine

Claims (6)

A long flat insulating substrate formed of a heat-resistant and insulating material;
A first and a second heating resistor formed in a thick film by a conductive component parallel to the longitudinal direction on the insulating substrate;
End heating resistors integrally formed of the same material as the heating resistors at both ends of the first and second heating resistors;
Supplying power to both ends of the first and second heating resistors connected in series, and an electrode formed on one end of the insulating substrate;
An overcoat layer applied on the insulating substrate leaving at least the electrodes, and
The end connected to the first heating resistor located on the upstream side through which the heated body that slides on the overcoat layer and is heated based on the first and second heating resistors first passes. A ceramic heater, wherein a resistance value of the partial heating resistor is formed lower than a resistance value of the end heating resistor connected to the second heating resistor.   2. The ceramic heater according to claim 1, wherein the end heat generating resistor is formed with a gradually increasing width as the first heat generating resistor and the second heat generating resistor are separated from each other.   3. The end heating resistor on the second heating resistor side is separated from a start position where the end heating resistor is gradually wider than the end heating resistor on the first heating resistor side. Ceramic heater.   3. The ceramic heater according to claim 2, wherein the width of the end heating resistor is linear or curved. The ceramic heater according to any one of claims 1 to 4,
A pressure roller disposed opposite to the ceramic heater and rotatably supported so as to press-contact the ceramic heater;
And a fixing film that is provided between the ceramic heater and the pressure roller and slides on the ceramic heater as the pressure roller rotates. 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;
6. A heating apparatus according to claim 5, wherein the toner is fixed by passing a sheet on which an image is formed while being pressed against the heater through a fixing film by a pressure roller. Image forming apparatus.

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