JP5381255B2 - Ceramic heater, heating device, image forming device - Google Patents

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, a facsimile, a rewritable card reader / writer, and the like, on which the heater is mounted. 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 amount of heat generated by this heating element is made different at the left and right ends, and the non-feeding electrode side from 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.

  Further, depending on the relationship of the system, contrary to the configuration of Patent Document 1, there is one in which the width of the heating resistor in the non-sheet passing portion is made larger than that in the sheet passing portion. In this case, there is a problem that the fixing property is deteriorated when the temperature of the edge portion decreases and the recording paper passes through this portion.

  An object of the present invention is to provide a ceramic heater that prevents cracking of the heater by preventing the fixing property of the recording paper passing through the end of the heater from being lowered, or suppressing the rapid increase in temperature at the end of the heater, and heating using this heater An apparatus and an image forming apparatus using the heating device are provided.

In order to solve the above-described problems, a ceramic heater according to the present invention is a thick film formed by a long flat insulating substrate formed of a heat-resistant and insulating material and a conductive component parallel to the longitudinal direction on the insulating substrate. A heating resistor formed, supplying power to both ends of the heating resistor, an electrode formed on one end of the insulating substrate, an overcoat layer applied on the insulating substrate leaving at least the electrode; And an end heating resistor is formed integrally at both ends of the heating resistor in the longitudinal direction of the portion to be heated, based on the heating resistor. The resistor is formed so that the width gradually decreases as the distance from the heat generating resistor increases , and the shape of the upstream end heat generating resistor that is to be touched later by the heated body gradually decreases in width. Gentler than the side Characterized by being formed.

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

The image forming apparatus according to the present invention includes a forming unit that forms a predetermined image by attaching toner to an electrostatic latent image formed on a medium and transferring the toner to a sheet, and pressurizes the sheet on which the image is formed. The heating apparatus according to claim 2 , wherein the toner is fixed by passing through the fixing film with a roller while being pressed against the heater.

  According to the present invention, it is possible to suppress a decrease in fixability without deteriorating the fixability of the recording paper passing through the end side of the ceramic heater. In addition, 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 an expanded sectional view of the IIa-IIb line | wire of FIG. It is explanatory drawing for demonstrating typically the temperature distribution of the heater longitudinal direction in FIG. It is a block diagram for demonstrating 2nd Embodiment regarding the ceramic heater of this invention. It is an expanded sectional view of the IIIa-IIIb line | wire of FIG. It is an expanded sectional view of the IVa-IVb line of FIG. It is explanatory drawing for demonstrating typically the temperature distribution of the heater longitudinal direction in FIG. It is a block diagram for demonstrating 3rd Embodiment regarding the ceramic heater of this invention. It is an expanded sectional view of the Va-Vb line | wire of FIG. It is an expanded sectional view of the VIa-VIb line | wire of FIG. It is explanatory drawing for demonstrating typically the temperature distribution of the heater longitudinal direction in FIG. It is a block diagram for demonstrating 4th Embodiment regarding the ceramic heater of this invention. 14A is an enlarged sectional view taken along line VIIa-VIIb in FIG. 13, FIG. 14B is an enlarged sectional view taken along line VIIIa-VIIIb in FIG. 13, and FIG. 14C is a sectional view taken along line IXa-IXb in FIG. It is an expanded sectional view. It is explanatory drawing for demonstrating typically the temperature distribution of the heater longitudinal direction in FIG. 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 in FIG. FIG. 4 is an enlarged sectional view taken along line 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. This is a belt-like heating resistor made of a thick film having a predetermined resistance value by firing a resistor paste at a high temperature.

  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. The electrode 14 is connected to one end of the heating resistor 12 and the electrode 15 is connected to one end of the heating resistor 13 via connection conductors 141 and 151, respectively. The other ends of the heating resistors 12 and 13 are commonly connected by a connection conductor 16 formed by firing a silver-based conductor paste. As a result, the heating resistors 12 and 13 are connected in series between the electrodes 14 and 15.

  A central region C in the longitudinal direction of the insulating substrate 11 of the heating resistors 12 and 13 is a paper passing region having a width of the recording paper through which the recording paper as the heated body is passed. Further, the heating resistors 12 and 13 in the end regions S1 and S2 located at both ends in the longitudinal direction of the insulating substrate 11 in the central region C are formed with a width B that gradually increases linearly from the width A of the central region C. The Thereby, in the end region S1, the end heating resistor 121 that gradually increases linearly from the width of the heating resistor 12 toward the open end is straightened from the width of the heating resistor 13 toward the open end. The end heating resistors 131 that are gradually wider are formed. In the end region S2, an end heating resistor 122 that gradually increases linearly from the width of the heating resistor 12 toward the open end is gradually increased linearly from the width of the heating resistor 13 toward the open end. Wide end heating resistors 132 are formed.

  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.

  Now, consider a case where the recording paper passes through the central area C. In this case, the recording paper is heated by heat generated by the width A of the heating resistors 12 and 13. At this time, the end heating resistors 121 and 131 located in the end region S1 have a shape that gradually increases linearly from the width A of the heating resistors 12 and 13 to the width B wider than this. That is, the resistance values of the end heat generating resistors 121 and 131 have a relationship in which the resistance value is closer to the end in the longitudinal direction of the insulating substrate 11. This also applies to the end heating resistors 122 and 132 in the end region S2.

  FIG. 4 is a schematic comparison of the temperature distribution between the case where the end regions S1 and S2 have the configuration shown in FIG.

  That is, in the conventional case shown by the broken line in FIG. 4, the temperature suddenly drops from the central region C to the end regions S1 and S2, so that the temperature necessary for fixing the recording paper cannot be obtained sufficiently and fixing failure occurs. Cause it to happen. On the other hand, in the case of the ceramic heater shown in FIG. 1 indicated by the solid line in FIG. 4, the resistance values of the end heating resistors 121, 122, 131, 132 in the end regions S1, S2 become gradually narrower. Therefore, as shown in the temperature distribution shown by the solid line in FIG. 4, the temperature gradually decreases from the central region C to the width B of the end regions S1 and S2, and the fixing property at the end portion of the insulating substrate 11 is obtained. It is possible to prevent a decrease in the above.

  In this embodiment, since the heating resistor is configured to gradually increase the width from the boundary between the central region and the end region to the open end of the end region, a gentle temperature drop from the central region in the insulating substrate end region is achieved. Thus, it becomes possible to eliminate heating defects.

  5 to 8 are diagrams for explaining the configuration of the second embodiment of the ceramic heater according to the present invention. FIG. 5 is a configuration diagram, FIG. 6 is an enlarged sectional view taken along line IIIa-IIIb in FIG. FIG. 8 is an enlarged sectional view taken along the line IVa-IVb in FIG. 5, and FIG. 8 is an explanatory diagram for schematically explaining the temperature distribution in the heater longitudinal direction in FIG. The same parts as those in the first embodiment described above are denoted by the same reference numerals, and description thereof is omitted here. The same applies to the following embodiments.

  In this embodiment, the heating resistors 12 and 13 in the end regions S1 and S2 are formed with a width B that gradually increases from the width A of the central region C in a curved manner. As a result, in the end region S1, the end heating resistor 123 that gradually increases in width from the width of the heating resistor 12 toward the open end is curved from the width of the heating resistor 13 toward the open end. Thus, end heating resistors 133 that are gradually widened are formed. In the end region S2, an end heating resistor 124 that gradually becomes wider from the width of the heating resistor 12 toward the open end is gradually curved from the width of the heating resistor 13 toward the open end. The wide end heating resistors 134 are formed.

  FIG. 8 is a schematic comparison of the temperature distribution between the case where the end regions S1 and S2 have the configuration shown in FIG.

  That is, in the conventional case shown by the broken line in FIG. 8, the temperature suddenly drops from the central region C to the end regions S1 and S2, and the fixing property to the recording paper due to the temperature difference in this portion is reduced. Become. On the other hand, in the case of the ceramic heater having the configuration shown in FIG. 5 indicated by the solid line in FIG. 8, the end heating resistors 123, 124, 133, and 134 in the end regions S <b> 1 and S <b> 2 are gradually reduced in resistance value. Therefore, as shown in the temperature distribution shown by the solid line in FIG. 8, the temperature gradually decreases from the central region C to the width B of the end regions S1 and S2, and the fixing at the end of the insulating substrate 11 is performed. It is possible to prevent a decrease in property.

  In this embodiment, since the heating resistor has a structure in which the width gradually increases from the boundary between the center region and the end region to the open end of the end region, the temperature drop in this region portion is also gently curved. It is possible to gradually reduce the temperature, and it is possible to eliminate heating defects.

  9 to 12 are for explaining the configuration of the third embodiment of the ceramic heater according to the present invention. FIG. 9 is a configuration diagram, FIG. 10 is an enlarged sectional view taken along the line Va-Vb in FIG. Is an enlarged sectional view taken along line VIa-VIb in FIG. 9, and FIG. 12 is an explanatory diagram for schematically explaining the temperature distribution in the heater longitudinal direction in FIG.

  In this embodiment, the heating resistors 12 and 13 in the end regions S1 and S2 which are non-sheet passing portions located at both ends in the longitudinal direction of the insulating substrate 11 in the central region C serving as a sheet passing portion are It is formed with a width E which is gradually narrowed linearly from the width D. As a result, the edge region S1 has an edge having the same width as the region where the width gradually decreases from the width of the heating resistor 13 on the upstream side through which the recording paper first passes toward the open end. A partial heating resistor 135 is formed. An end heating resistor 125 having a region having the same width as the region where the width gradually decreases from the width of the downstream heating resistor 12 through which the recording paper passes later toward the open end is formed. Similarly, in the end region S2, an end heating resistor 126 having a region having the same width as the region that gradually decreases in width linearly from the width of the heating resistor 12 toward the open end is provided in the heating resistor. End heating resistors 136 each having a region having the same width as a region that gradually narrows linearly from the width of 13 toward the open end are formed.

  In this manner, the upstream heating resistor 13 and the downstream heating resistor 12 are gradually narrowed linearly from the width D of the central region C to the width E of the end regions S1 and S2. As a result, in the conventional case shown by the broken line in FIG. 12, the temperature suddenly increases from the central region C to the end regions S1 and S2, and this causes a crack in the insulating substrate 11 due to the temperature difference in this portion. . On the other hand, in the case of the ceramic heater having the configuration shown in FIG. 9 shown by the solid line in FIG. 12, the resistance values of the end heating resistors 123, 124, 133, and 134 in the end regions S1 and S2 are gradually increased. The temperature gradually increases from the central region C to the width B of the end regions S1 and S2, so that a rapid temperature difference can be suppressed and cracking of the insulating substrate 11 can be prevented.

  In this embodiment, since the heating resistor has a structure in which the width is gradually narrowed linearly from the boundary between the central region and the end region to the open end of the end region, the temperature rise in this region portion is also moderately linear. It is possible to suppress the rapid temperature difference and to prevent the insulating substrate 11 from cracking.

  FIGS. 13 to 15 are diagrams for explaining a fourth embodiment of the ceramic heater according to the present invention. FIG. 15 is a structural view, FIG. 14 (a) is an enlarged sectional view taken along line VIIa-VIIb of FIG. (B) is an enlarged sectional view taken along line VIIIa-VIIIb in FIG. 13, FIG. 14 (c) is an enlarged sectional view taken along line IXa-IXb in FIG. 13, and FIG. 15 schematically shows the temperature distribution in the heater longitudinal direction in FIG. It is explanatory drawing for demonstrating.

  In this embodiment, the amount of gradually narrowing from the width D of the central region C of the upstream heating resistor 13 and the downstream heating resistor 12 to the width E of the end regions S1, S2 is defined as the upstream side. It changes on the downstream side. That is, the end heat generating resistors 137 and 138 of the end regions S1 and S2 of the upstream heat generating resistor 13 are formed so as to be gradually narrowed linearly from the boundary with the central region C to the distance La. . The end heat generating resistors 127 and 128 of the end regions S1 and S2 of the downstream heat generating resistor 12 are gradually narrowed linearly from the boundary with the central region C to a distance Lb longer than the distance La. Formed.

  As a result, in the conventional case shown by the broken lines in FIGS. 15A and 15B, the temperature suddenly rises from the central region C of the heating resistors 13 and 12 to the end regions S1 and S2. This causes a crack of the insulating substrate 11 due to a temperature difference at.

  On the other hand, in the case of the heating resistor 13 of the ceramic heater shown in FIG. 13 shown by the solid line in FIG. 15A, the resistance values of the end heating resistors 137 and 138 in the end regions S1 and S2 gradually increase. Since it increases, the temperature gradually increases from the central region C to the width B of the end regions S1 and S2, so that a rapid temperature difference can be suppressed and cracking of the insulating substrate 11 can be prevented. .

  In the case of the heating resistor 12 of the ceramic heater having the configuration shown in FIG. 13 indicated by the solid line in FIG. 15B, the resistance values of the end heating resistors 127 and 128 in the end regions S1 and S2 are gradually increased. Therefore, the temperature gradually increases from the center region C to the width B of the end regions S1 and S2, and a rapid temperature difference can be suppressed, and the insulating substrate 11 can be prevented from cracking.

  In this case, the shape in which the widths of the downstream end heat generating resistors 127 and 128 are narrower than the shape in which the widths of the upstream end heat generating resistors 137 and 138 are narrower. . Since the upstream heating resistor 13 is in contact with the lower temperature recording paper than the downstream side, the temperature drop is large. Therefore, the heat generation area of the end region is increased by forming the slope of the switching portion between the central region and the end region of the upstream heating resistor 13 more gently than the downstream side, thereby increasing the upstream and downstream end portions. It is possible to balance the amount of heat generated in the region, suppress a rapid temperature difference, and prevent substrate cracking.

  In this embodiment, the upstream side through which the recording paper first passes and the downstream side through which the downstream heating resistor passes are formed such that the slope of the switching portion between the central part and the end part of the heating resistor is gentler on the upstream side than on the downstream side. By increasing the heat generation area of the downstream end region, it is possible to balance the heat generation amount of the upstream end region and the downstream end region, suppress a sudden temperature difference, and prevent insulation substrate cracking. Is possible.

  In the third and fourth embodiments relating to the ceramic heater of the present invention described above, the case has been described in which the portion where the progressive width of the end heating resistor is narrowed is linear, but as in the second embodiment. It may be curved. Further, although an example has been given in which the width is gradually narrowed or widened linearly or curvedly, the same effect can be obtained even if the thickness of the heating resistor having the same width is gradually changed.

  Next, an embodiment relating to 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 the block diagram shown in the cross section of FIG. Reference numeral 100 in the figure denotes the ceramic heater described in FIGS. 1 to 3, and the same parts are denoted by the same reference numerals, and the description thereof is omitted.

  In FIG. 16, reference numeral 201 denotes a stainless steel that adheres the ceramic heater 100 to the bottom of the support 202, supplies an alternating voltage to the ceramic heater 100, and moves while being pressed and heated to the overcoat layer 19 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. Reference numeral 203 denotes a pressure roller having a heat resistant elastic material, for example, a silicone rubber layer 204 fitted on the surface thereof. The ceramic heater 100 is juxtaposed with the fixing film 201 so as to face 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.

  At this time, the toner image To1 is first heated and melted by the ceramic heater 100 via the fixing film 201 between the surface of the fixing film 201 disposed on the overcoat layer 19 and the silicone rubber layer 204, and at least the surface portion thereof is 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 and cooled and solidified again, and the fixing film 201 is also separated from the copy paper P.

  In this embodiment, it is possible to eliminate the heating failure from the gentle temperature drop from the central region in the end region of the ceramic heater.

  In addition, when the ceramic heater of the present invention described with reference to FIGS. 9 to 11 is used as the ceramic heater 100, the temperature rise in the end region can be linearly and gently increased to suppress an abrupt temperature difference. The crack of the heater 100 can be prevented.

  Next, with reference to FIG. 17, 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. 17, 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 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 against 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 the heat of the heating resistors 12 and 13 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.

  In this embodiment, when the non-sheet passing portion of the heating resistor of the ceramic heater is wide, the fixing device is excellent in fixing property because a heating device that can prevent deterioration in fixing property when the recording paper passes therethrough is used. An image forming apparatus can be realized.

  In addition, when the non-sheet-passing part of the heating resistor of the ceramic heater is narrow, the use of a heating device that suppresses the abrupt temperature difference and prevents the insulating substrate from cracking prevents cracking of the ceramic heater. It is possible to realize an image forming apparatus excellent in the above.

  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, equipment for chemical reactions, etc. 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, S2 End region 100 Ceramic heater 200 Heating Apparatus 201 Fixing film 203 Pressure roller 300 Copying machine

Claims (3)

A long flat insulating substrate formed of a heat-resistant and insulating material;
A heating resistor having a thick film formed of a conductive component parallel to the longitudinal direction on the insulating substrate;
Supplying power to both ends of the heating resistor, an electrode formed on one end of the insulating substrate;
An overcoat layer applied on the insulating substrate leaving at least the electrodes, and
Based on the heating resistor, an end heating resistor is formed integrally at both ends of the heating resistor in the longitudinal direction of the portion to be heated normally, and the end heating resistor is As the distance from the heating resistor increases, the width gradually decreases , and the width of the end heating resistor on the parallel downstream side that the heated body touches later becomes gradually narrower than the upstream side. A ceramic heater characterized in that it is formed . A ceramic heater according to claim 1 ;
A pressure roller disposed opposite to the ceramic heater and rotatably supported so as to press-contact the ceramic heater;
A heating apparatus comprising: a fixing film provided between the ceramic heater and the pressure roller and sliding 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;
A heating device according to claim 2 , wherein the toner is fixed by passing a sheet on which an image is formed through a fixing film while being pressed against the heater by a pressure roller. Image forming apparatus.

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