JP5320549B2 - 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 devices such as information equipment, home appliances, and manufacturing equipment, and a heating device such as a printer, a copying machine, a facsimile, a rewritable card reader / writer, and the like mounted with the ceramic heater, The present invention relates to an image forming apparatus using the heating device.

  A ceramic heater in which a heating resistor having a length in the short side and a width in the longitudinal direction is formed on a conventional long flat plate-like ceramic substrate is shortened as the distance from the power feeding position increases. The temperature distribution in the longitudinal direction of the ceramic substrate is made uniform by reducing the difference in resistance value due to the conductive path between the feeding electrode forming side and the non-feeding electrode forming side (for example, Patent Document 1).

JP 2007-157456 A

  The technique of Patent Document 1 described above can obtain a uniform temperature distribution when a fixing object having a heater length is passed through. However, when a sheet to be fixed that is shorter than the heater length is passed through, for example, when the heater central part is 200 ° C. and the end part is 240 ° C., the resistance value of the wiring pattern becomes several Ω, There was a problem that a resistance value difference of several percent occurred at both ends of the ceramic substrate, the amount of heat generated on the power supply electrode formation side increased, and fixing unevenness occurred when the traveling speed of the fixing object was increased.

  An object of the present invention is to provide a ceramic heater capable of speeding up the rise when supplying power and suppressing the temperature rise at the non-sheet passing portion during fixing, a heating device mounted with the heater, and an image forming device mounted with the heating device. To provide an apparatus.

  In order to solve the above-described problems, a ceramic heater according to the present invention includes a long flat heat-resistant and insulating ceramic substrate, and a heating resistor having a length in the short side and a width in the long direction on the ceramic substrate. And first and second wiring patterns formed along the longitudinal ends of the heating resistor and connected to both ends of the heating resistor, and the first wiring pattern formed on the ceramic substrate for supplying power. A first electrode connected to a longitudinal central portion of the ceramic substrate of the wiring pattern; a second electrode connected to a longitudinal central portion of the ceramic substrate of the second wiring pattern; and the heating resistor. And an insulating overcoat layer for protecting the first and second wiring patterns, wherein the first and first wiring patterns have a high resistance temperature coefficient.

  A heating device according to the present invention includes the ceramic heater according to any one of claims 1 to 9, a pressure roller that is disposed so as to face the ceramic substrate and is rotatably supported so as to press-contact the ceramic substrate, A fixing film is provided between the ceramic substrate and the pressure roller and slides on the ceramic substrate 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 device according to claim 10, 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 start up quickly when power is supplied, and to suppress the temperature rise of the non-sheet passing portion during fixing.

BRIEF DESCRIPTION OF THE DRAWINGS It is for demonstrating 1st Embodiment regarding the ceramic heater of this invention, (a) is a front view, (b) is a rear view. FIG. 2 is a sectional view taken along line Ia-Ib in FIG. 1. Ic-Id line sectional drawing of FIG. FIG. 2 is a cross-sectional view taken along line Ie-If in FIG. 1. The equivalent circuit for demonstrating the operation | movement of FIG. The block diagram for demonstrating 2nd Embodiment regarding the ceramic heater of this invention. 7 is an equivalent circuit for explaining the operation of FIG. (A) for demonstrating 3rd Embodiment regarding the ceramic heater of this invention is a front view, (b) is a rear view. Sectional drawing of the IIa-IIb line | wire of FIG. Sectional drawing of the IIc-IId line | wire of FIG. Sectional drawing of the IIe-IIf line | wire of FIG. The block diagram for demonstrating 4th Embodiment regarding the ceramic heater of this invention. The block diagram for demonstrating 5th Embodiment regarding the ceramic heater of this invention. The block diagram for demonstrating 6th Embodiment regarding the ceramic heater of this invention. The block diagram for demonstrating 7th Embodiment regarding the ceramic heater of this invention. (A) for demonstrating 8th Embodiment regarding the ceramic heater of this invention is a front view, (b) is a rear view. Sectional drawing of the IIIa-IIIb line | wire of FIG. Sectional drawing of the IIIc-IIId line | wire of FIG. 16 is an equivalent circuit of the main part. Explanatory drawing for demonstrating one Embodiment regarding the heating apparatus of this invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG.

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

  1 to 4 are for explaining a first embodiment of the ceramic heater according to the present invention. FIG. 1 (a) is a front view, FIG. 1 (b) is a rear view, and FIG. 3 is a cross-sectional view taken along line Ia-Ib, FIG. 3 is a cross-sectional view taken along line Ic-Id in FIG. 1, and FIG. 4 is a cross-sectional view taken along line Ie-If in FIG.

  In the following embodiments, the same components as those in this embodiment will be described with the same reference numerals. Further, although the right side of the heating resistor will be described, the concept is the same for the left side, and the description thereof will be omitted.

In FIG. 1A, 11 is a heat-resistant and electrically insulating material having a thickness of about 0.5 mm to 1.0 mm, and has high thermal conductivity, such as alumina (Al ₂ O ₃ ), aluminum nitride (AlN), etc. This is a flat plate-shaped ceramic substrate made of a highly rigid ceramic. Reference numerals 12 and 13 formed on one end side in the longitudinal direction of the ceramic substrate 11 are power supply electrodes made of a good conductor film mainly composed of silver or the like. Reference numerals 14 and 15 are wiring patterns formed of a material having a silver (Ag) content of 90 wt% or more in parallel in a non-contact state on both sides in the longitudinal direction of the ceramic substrate 11.

  The electrodes 12 and 13 and the wiring patterns 14 and 15 are respectively formed in separate states on one surface of the ceramic substrate 11. The electrodes 12 and 13 and the wiring patterns 14 and 15 can be formed in a state of being fixed on the ceramic substrate 11 by applying a conductive paste on the ceramic substrate 11 and firing the paste.

  As shown in FIG. 1B, a connection pattern 16 for connecting the electrode 12 and the wiring pattern 14 is formed at a position facing the longitudinal direction of the wiring pattern 14 across the ceramic substrate 11. Similarly, a connection pattern 17 for connecting the electrode 13 and the wiring pattern 15 is formed at a position facing the longitudinal direction of the wiring pattern 15 across the ceramic substrate 11.

  As shown in FIGS. 2 and 3, the electrode 12 and the connection pattern 16 are electrically connected through the through hole 181. The wiring pattern 14 and the connection pattern 16 are electrically connected through the through hole 182. The electrode 13 and the connection pattern 17 are electrically connected via a through hole 191, and the wiring pattern 15 and the connection pattern 17 are electrically connected via a through hole 192.

Reference numeral 20 denotes a high-temperature resistor paste that is formed in parallel with the longitudinal direction of the ceramic substrate 11 between the wiring patterns 14 and 15 and screened with a resistor paste such as ruthenium oxide (RuO ₂ ) having a relatively high resistance value. And a wide heating resistor having a predetermined resistance value and a film thickness of about 10 μm. The resistance temperature coefficient (TCR: Temperature Coefficient of Resistance) of the wiring patterns 14 and 15 is set to a large value, for example, 3000 ppm / ° C.

  As shown in FIGS. 3 and 4, the wiring pattern 14, the heating resistor 20, the wiring pattern 15, and the heating resistor 20 are partially stacked. In this case, the multilayer portion has a relationship in which the heating resistor 20 is disposed on the upper side with respect to the wiring patterns 14 and 15. This relationship may be reversed.

  No. 21 is formed so as to cover the wiring patterns 14 and 15 and the heating resistor 20, and has a glass layer thickness of about 20 μm to 100 μm and an excellent thermal conductivity such as alumina having a thermal conductivity of, for example, 2 W / m · K or more. By adding 25 wt% to 35 wt% of an inorganic oxide filler, it is an overcoat layer such as glass whose slidability is improved. The overcoat layer 21 protects the wiring patterns 14 and 15 and the heating resistor 20 mechanically, chemically, and electrically.

  Here, one of the heating resistors 20 from the electrode 12 through the through hole 181, the connection pattern 16, the through hole 182, and the wiring pattern 14, and the electrode 13 from the through hole 191, the connection pattern 17, the through hole 192, and the wiring pattern 15. When the other of the heating resistor 20 is energized through the heating resistor 20, the heating resistor 20 generates heat.

  Here, the operation will be described together with the equivalent circuit of FIG. 5 shows the resistance of the wiring pattern 14 from the through hole 182 shown in FIG. 1 to the end portion where the heating resistor 20 is located, and the resistance of the wiring pattern 15 from the through hole 192 to the end portion where the heating resistor 20 is located. R15, the resistance of the wiring pattern 14 from the through hole 182 to the heating resistor 20 is R14b, the resistance of the wiring pattern 15 from the through hole 192 to the heating resistor 20 is R15b, and the resistance of the heating resistor 20 between the resistor R14b and the resistor R15b. The resistance is indicated by R20a, and the resistance of the heating resistor 20 between the ends of the wiring patterns 14 and 15 is indicated by R20b.

  Here, a specific example will be described. The length of the heating resistor 20 is 2 mm, the width is 240 mm, the length of the wiring patterns 14 and 15 formed at both ends is 240 mm, the width is 1 mm, the resistance value of the heating resistor 20 is 2400 Ω / □, resistance The temperature coefficient is 0 ppm / ° C., the wiring patterns 14 and 15 are 4 mΩ / □, and the resistance temperature coefficient is 3000 ppm / ° C. The resistance value of the heating resistor 3 is 20Ω.

  When the heating resistor 20 is at room temperature, the values of the resistors R14b and R15b are extremely small, 0Ω, the resistor R20a is 20Ω, and the resistor R14a + R15a is, for example, 0.96Ω. In this case, the resistance value between the through holes 182 and 192 is 20Ω (R14b + R20a + R15b).

  Further, the resistance value from the through hole 182 to the end of the wiring pattern 14, the heating resistor 20, and the wiring pattern 15 from the end of the wiring pattern 15 to the through hole 192 at room temperature is 20.96Ω (R14a + R20b + R15a). .

  When the heating resistor 20 is 180 ° C., the values of the resistors R14b and R15b are extremely small 0Ω, the resistor R20a is 20Ω, and the resistor R14a + R15a is 1.392Ω. The resistance value between the through holes 182 and 192 at 180 ° C. is 20Ω (R14b + R20a + R15b).

  The resistance values of the wiring patterns 14 and 15 from the through hole 182 to the end of the wiring pattern 14 at 180 ° C., the heating resistor 20 and the wiring pattern 15 from the end of the wiring pattern 15 to the through hole 192 are 21.39Ω. It becomes. The difference in the case of room temperature is because the resistance temperature coefficient of the wiring patterns 14 and 15 is 3000 ppm / ° C.

  That is, the resistance R14b + R15b of the wiring patterns 14 and 15 is 0.16Ω at room temperature (30 ° C.), but the resistance value of the wiring patterns 14 and 15 has a resistance temperature coefficient of 3000 ppm / ° C. Therefore, when it reaches 180 ° C., it is 0.16 × (1 + 3000/1000000 × (180−30)) = 0.232Ω, so that the resistance value between the through holes 182 and 192 in the center is 20. That means 23Ω.

  From the same idea, the resistances R14a and 15a of the wiring patterns 14 and 15 when the temperature is changed from room temperature to 180 ° C. also increase.

  Therefore, when the heater close to room temperature rises, the difference between the resistance values of the middle and end portions of the heater near the through holes 182 and 192 is small, so that the entire heater rises quickly. Further, when the fixing temperature is 180 ° C., the apparent resistance temperature coefficient at the ends of the wiring patterns 14 and 15 can be increased, so that the current flowing near the ends can be reduced. For this reason, when a temperature difference arises in an edge part and a center part, it becomes possible to control the calorific value of an edge part.

  6 and 7 are diagrams for explaining a second embodiment of the ceramic heater according to the present invention, FIG. 6 is a front view, and FIG. 7 is an equivalent circuit for explaining the operation.

  In this embodiment, the through hole 182 is shifted by a distance L1 along the wiring pattern 14 and the through hole 192 is shifted by a distance L2 along the wiring pattern 15 from the center C in the width direction of the heating resistor 20. It has been made.

  Here, the values of the resistors R14b and R15b at room temperature increase by the amount that the through hole 182 is shifted by L1 and the through hole 192 is shifted by L2, respectively, and become 0.16Ω. It is assumed that the resistance R20b in the length direction of the heating resistor is 20Ω and the resistances R14a + R15a are 0.96Ω. In this case, the resistance value between the through holes 182 and 192 is 20.23Ω (R14b + R20a + R15b). Further, the resistance value from the through hole 182 to the end of the wiring pattern 14, the heating resistor 20, and the end of the wiring pattern 15 to the wiring pattern 15 at the room temperature is 21.39Ω.

  When the heating resistor 20 is 180 ° C., the values of the resistors R14b and R15b are extremely small and substantially 0Ω, the resistor R20a is 20Ω, and the resistor R14a + R14a is 1.392Ω. The resistance value between the through holes 182 and 192 at the time of fixing at 180 ° C. is 20Ω (R14b + R20a + R15b).

  The resistance value from the through hole 182 to the end of the wiring pattern 14, the heating resistor 20, and the wiring pattern 15 from the end of the wiring pattern 15 to the through hole 192 at 180 ° C. is 21.39Ω (R14a + R20b + R15a).

  In this embodiment, the resistance value between the central through-holes 182 and 192 at room temperature is 20.16Ω, and the resistance value between the end through-holes 182 and 192 is 20.96Ω. This increases the heater start-up speed as in the first embodiment of the ceramic heater described above.

  Further, at 180 ° C. at the time of fixing, the current flowing near the ends of the wiring patterns 14 and 15 can be reduced by the action of the resistance temperature coefficient of 3000 ppm / ° C. of the wiring patterns 14 and 15. Therefore, when a temperature difference occurs between the central portion and the end portion during paper feeding, it is possible to suppress the heat generation amount at the end portion.

  8 to 11 are views for explaining a third embodiment of the ceramic heater according to the present invention. FIG. 8A is a front view, FIG. 8B is a rear view, and FIG. 9 is IIa- in FIG. FIG. 10 is a sectional view taken along line IIb, FIG. 10 is a sectional view taken along line IIc-IId in FIG. 8, and FIG. 11 is a sectional view taken along line IIe-IIf in FIG.

  In this embodiment, the wiring patterns 142 and 143 and the wiring patterns 152 and 153 are formed by narrowing the widths at both ends of the wiring patterns 14 and 15 within the width L3 of the central portion in the width direction of the heating resistor 20. . The wiring patterns 142, 143, 152, and 153 are narrower by about 5% than the widths of the wiring patterns 141 and 151 at the center.

  In this case, the resistances R14b and R15b between the through-hole 182 and the heating resistor 20 in the central portion at room temperature and between the through-hole 192 and the heating resistor are extremely short and substantially 0Ω, so that 20Ω ( R14b + R20a + R15b). Assuming that the resistance value of the wiring patterns 143 and 153 at the end is 1.01Ω, which is higher by 5%, the resistance value of the end including the heating resistor 20 is 21.01Ω (R14a + R20b + R15a).

  At the time of fixing at 180 ° C., the resistance at the center is 20Ω, and the resistance at the end is the resistance R14a of the wiring pattern 14, the resistance R20b of the heating resistor 20, the resistance R15a of the wiring pattern 15, and the resistance temperature of the wiring patterns 14 and 15. When the coefficient is added, it becomes 21.39Ω.

  As described above, when the heater rises close to room temperature, the difference between the resistance values of the middle and end portions of the heater near the through holes 182 and 192 is small, so that the rise of the entire heater is accelerated. When the fixing temperature is 180 ° C., the current flowing near the ends of the wiring patterns 14 and 15 can be reduced, and the apparent resistance temperature coefficient of the ends can be increased. When a temperature difference occurs in the central portion, the amount of heat generated at the end can be suppressed.

  FIG. 12 is a block diagram for explaining a fourth embodiment of the ceramic heater of the present invention.

  In this embodiment, the through holes 182 and 192 of the third embodiment of the ceramic heater described above are shifted in a direction away from each other by a distance of L1 and L2 from the intermediate portion C as shown in FIG.

  In this case, the values of the resistors R14b and R15b at room temperature increase by the amount that the through hole 182 is shifted by L1 and the through hole 192 is shifted by L2, respectively, and become 0.16Ω. It is assumed that the resistance R20b in the length direction of the heating resistor 20 is 20Ω and the resistances R14a + R15a are 0.96Ω. In this case, the resistance value between the through holes 182 and 192 is 20.16Ω (R14b + R20a + R15b). Further, the resistance value from the through hole 182 to the end of the wiring pattern 14, the heating resistor 20, and the end of the wiring pattern 15 to the wiring pattern 15 at the room temperature is 21.39Ω.

  When the heating resistor 20 is 180 ° C., the values of the resistors R14b and R15b are extremely small and substantially 0Ω, the resistor R20b is 20Ω, and the resistors R14a + R14a are 1.392Ω. The resistance value between the through holes 182 and 192 at the time of fixing at 180 ° C. is 20Ω (R14b + R20a + R15b).

  The resistance value from the through hole 182 to the end of the wiring pattern 14, the heating resistor 20, and the wiring pattern 15 from the end of the wiring pattern 15 to the through hole 192 at 180 ° C. is 21.39Ω (R14a + R20b + R15a).

  In this embodiment, the resistance value between the central through-holes 182 and 192 at room temperature is 20.16Ω, and the resistance value between the end through-holes 182 and 192 is 20.96Ω. This increases the heater start-up speed as in the first embodiment of the ceramic heater described above.

  Further, at 180 ° C. at the time of fixing, the current flowing near the ends of the wiring patterns 14 and 15 can be reduced by the action of the resistance temperature coefficient of 3000 ppm / ° C. of the wiring patterns 14 and 15. Therefore, when a temperature difference occurs between the central portion and the end portion during paper feeding, it is possible to suppress the heat generation amount at the end portion.

  FIG. 13 is a block diagram for explaining a fifth embodiment relating to the ceramic heater of the present invention.

  In this embodiment, the wiring patterns 14 and 15 at the end of the fourth embodiment of the ceramic heater described above are arranged in the width direction of the ceramic substrate 11 which is the length of the diaphragm heating resistor 20 on the heating resistor 20 side. The heating resistors 202 and 203 at the end are shorter than the heating resistor 201 at the center.

  The values of the resistors R14b and R15b at room temperature having such a configuration increase to the amount that the through-hole 182 is shifted by L1 and the through-hole 192 is shifted by L2, and are each 0.16Ω. It is assumed that the resistance R20b in the length direction of the heating resistor 20 is 20Ω and the resistances R14a + R15a are 0.96Ω. In this case, the resistance value between the through holes 182 and 192 is 20.16Ω (R14b + R20a + R15b).

  Further, the resistance values from the through hole 182 to the end of the wiring pattern 14, the heating resistor 20, and the end of the wiring pattern 15 to the through hole 192 at room temperature are resistances corresponding to the length of the heating resistor 20 being increased. Since the value decreases to 19.2Ω and the resistance value of the wiring patterns 14 and 15 is 0.96Ω, it becomes 20.16Ω (R14a + R20b + R15a). At room temperature, the resistance values between the central and end through holes 182 and 192 are the same.

  When the heating resistor 20 has a fixing temperature of 180 ° C., the value of the resistor R14b + R15b is 0.232Ω, and the resistor R20a is 20Ω. Accordingly, the resistance value between the through holes 182 and 192 at the fixing temperature of 180 ° C. is 20.23Ω (R14b + R20a + R15b).

  Considering the resistance temperature coefficient of 3000 ppm / ° C. of the wiring patterns 14 and 15 at 180 ° C., the resistance R 14 from the through hole 182 to the end of the wiring pattern 14 and the resistance R 15 from the through hole 192 to the end of the wiring pattern 15 are 1.392Ω. Further, the resistance R20b of the heating resistor at the end is 19.2Ω, which is the same as that at room temperature because the temperature coefficient of resistance is zero. Therefore, the resistance between the through holes 182 and 192 at 180 ° C. at the end is 20.59Ω (R14a + R20b + R15a).

  In this embodiment, the resistance value between the central through holes 182 and 192 at room temperature is 20.16Ω, and the resistance value between the end through holes 182 and 192 is 20.16Ω. The amount of current at the center and end of the heater is the same condition, and the temperature of the entire heater can be made uniform when starting up. When the temperature at the end portion at which the sheet is not passed due to the fixing temperature rises, the resistance value at the end portion increases, so that the amount of current can be suppressed.

  FIGS. 14 and 15 are configuration diagrams for explaining the sixth and seventh embodiments of the ceramic heater of the present invention, respectively.

  In the embodiment of FIG. 14, the length of the heating resistor 20 is the same, and the widths of the wiring patterns 14 and 15 connected to both ends of the heating resistor 20 are directed outward from the intermediate portion in the width direction of the heating resistor 20. Gradually narrowed.

  In addition to the embodiment of FIG. 14, the embodiment of FIG. 15 is such that the length of the heating resistor 20 is gradually shortened from the widthwise intermediate portion toward the outside.

  14 and 15 are formed by changing the width of the wiring patterns 14A and 15B or the length of the wiring patterns 14A and 15A and the heating resistor 20A in a tapered shape from the center to the end of the heater. The calorific value can be continuously changed in the longitudinal direction of the ceramic substrate 11. For this reason, it becomes possible to cope with the size of any object to be fixed.

  16 to 19 are views for explaining an eighth embodiment of the present invention. FIG. 16 (a) is a front view, FIG. 16 (b) is a rear view, and FIG. 17 is a sectional view taken along line IIIa-IIIb in FIG. 18 is a cross-sectional view taken along the line IIIc-IIId in FIG. 16, and FIG. 19 is an equivalent circuit of the main part in FIG.

  In this embodiment, for example, 1Ω sub-wiring patterns 16a and 16b are provided at both ends of the width L3 of the central portion of the wiring pattern 14 in the longitudinal direction, and the wiring pattern 15 is also provided at both ends of the same range, for example, 1Ω sub-wiring. The wiring patterns 16c and 16d are formed in a connected state in which the wiring patterns 16c and 16d are electrically overlapped with each other. Further, the heating resistor 20 is formed in a connected state in which the width in the range of the central portion L3 of the heating resistor 20 and the auxiliary heating resistor 16e having the same length as the heating resistor 20 are electrically overlapped.

Here, examples will be described. The length of the wiring patterns 14 and 15 is assumed to be formed using a RuO ₂ resistor having a length of 2 mm, a width of 240 mm, a resistance of 2400 Ω / □, and a resistance temperature coefficient of 0 ppm / ° C. It is assumed that 240 mm, width is 1 mm, resistance is 25 mΩ / □, and TCR is formed by an Ag-based wiring pattern of 3000 ppm / ° C. The auxiliary heating resistor 16e has a length of 2 mm, a width of 80 mm, a resistance of 34 kΩ / □, a resistance temperature coefficient of 0 ppm / ° C., a RuO ₂ resistor, and the auxiliary wiring patterns 16a to 16d having a length of 80 mm and a width. It is assumed that each is formed with an Ag wiring pattern having a sheet resistance of 4 mΩ / □ and a TCR of 3000 ppm / ° C. at 1 mm.

  In this case, the resistance values at the center and the end are both 60.3Ω. That is, the resistance value between the central through hole 182 and 192 is 60.3Ω (R14b + R20a + R15b), and the resistance value between the end portion and the through hole 182 and 192 is 60.3Ω (R14a + R20b + R15a). However, R20a is a combined resistance value of the heating resistor 20 and the sub-heating resistor 16e, R14b is a combined resistance value of the wiring pattern 14 and the sub-wiring pattern 16b, and R15b is a combined resistance value of the wiring pattern 15 and the sub-wiring pattern 16d. Value.

  Thereby, a uniform temperature distribution in the longitudinal direction of the ceramic substrate 11 can be realized.

  When a material to be fixed that is short with respect to the heater length is passed through and the heater central part is 200 ° C. and the end part is 240 ° C., the resistance value of the central part is 60.5Ω (R14b + R15b = 0.5Ω, R20a = 60Ω), and the resistance value at the end is 63.0Ω (R14a + R15a = 7Ω, R20b = 56Ω), so a resistance value difference of about 4% occurs, and the difference in resistance between the center and the end is large. It is possible to improve the effect of suppressing energization.

  The ceramic heater of the present invention is not limited to the above-described embodiment. For example, the through-holes for explaining the electrodes 12 and 13 and the middle in the width direction of the heating resistor 20 may be formed by forming a wavy pattern that changes to a through-hole in the ceramic substrate 11 on the same plane as the wiring patterns 14 and 15. A similar configuration can be realized.

  The resistance temperature coefficient of the wiring patterns 14 and 15 is 3000 ppm / ° C. as an example. However, if the resistance temperature coefficient is 3000 ppm / ° C. or more, the resistance value at the end at the fixing temperature where the effect can be obtained can be increased. There is an effect to suppress.

  FIG. 20 is a cross-sectional view when a heater unit in which the ceramic heater 100 described above is attached to a heater support for mounting an embodiment of the heating apparatus of the present invention is mounted on the heating apparatus 200. 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. 20, reference numeral 201 denotes a cylindrical fixing film in which a heat-resistant film such as polyimide resin is rolled and wound in a circulating manner. The fixing film 201 is fixed to the bottom of the support 202, the ceramic heater 100 is fixed, electric power is supplied to the ceramic heater 100, and the fixing film 201 is moved to the overcoat layer 21 formed on the heated ceramic heater 100 while being pressed and heated.

  Reference numeral 203 denotes a pressure roller, which is a heat-resistant elastic material, for example, a silicone rubber layer 204 fitted on the surface thereof. The ceramic heater 100 faces the rotation shaft 205 of the pressure roller 203 and the fixing film 201. And mounted in a base (not shown). The pressure roller 203 is brought into pressure contact with the fixing film 201 to form a nip portion N formed by the heating resistor 20 and the pressure roller 203, and each 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 through the fixing film 201 between the surface of the fixing film 201 disposed on the overcoat layer 20 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 to be cooled and solidified again, and the fixing film 201 is also separated from the copy paper P.

  In this embodiment, by using a ceramic heater that can suppress the temperature rise in the non-sheet passing portion, the temperature rise can be speeded up and the temperature rise in the non-sheet passing portion can be suppressed. Become.

  Next, with reference to FIG. 21, an image forming apparatus according to the present invention will be described in the case where a copying machine equipped with the heating device 200 according to the present invention is taken as an example. In the figure, the part of the heating device 200 is the same as that described in FIG. 20, and the same reference numerals are given to the same parts, and the description thereof is omitted.

  In FIG. 21, 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 Z 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 the heat of the heat generating resistor 20 and has characters, alphanumeric characters and symbols on the copy paper P surface. A copy image such as a drawing is displayed.

  In this embodiment, since the heating device provided with the ceramic heater that suppresses the speeding up of the rise and suppresses the temperature rise in the non-sheet passing portion is used, it is possible to take a sufficient heat countermeasure with a quick rise.

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

11 Ceramic substrate 12, 13 Electrode 14, 15, 141, 142, 143, 151, 152, 153, 14A, 15A Wiring pattern 16, 17 Connection pattern 181, 182, 191, 192 Through hole 20, 201, 202, 203 Heat generation Resistor 21 Overcoat layers 16a to 16d Sub-wiring pattern 16e Sub-heating resistor 100 Ceramic heater 200 Heating device 201 Fixing film 203 Pressure roller 300 Copying machine

Claims (5)

A heat-resistant and insulating long flat ceramic substrate;
A heating resistor formed on the ceramic substrate and having a length in the short direction and a width in the long direction of the ceramic substrate;
First and second wiring patterns respectively formed at both ends of the heating resistor in the longitudinal direction so as to be connected to the heating resistor;
A first electrode formed on the ceramic substrate so as to be connected to a longitudinal central portion of the ceramic substrate of the first wiring pattern;
A second electrode formed on the ceramic substrate so as to be connected to a longitudinal central portion of the ceramic substrate of the second wiring pattern;
An insulating overcoat layer for protecting the heating resistor,
The first and second wiring patterns have a resistance temperature coefficient of 3000 ppm / ° C. or higher, and a sub-heating resistor having a resistance value different from that of the heating resistor is electrically connected to the central portion of the heating resistor. Sub-wiring patterns having resistance values different from those of the first and second wiring patterns are formed on both ends of the central portion of the first and second wiring patterns. A ceramic heater characterized by that.   The connection between the first electrode and one end of the heating resistor and the connection between the second electrode and the other end of the heating resistor are on the back side of the ceramic substrate on which the heating resistor is formed, The ceramic heater according to claim 1, wherein the ceramic heater is connected through a through hole.   The connection between the first electrode and one end of the heating resistor and the connection between the second electrode and the other end of the heating resistor are formed on the same surface as the ceramic substrate on which the heating resistor is formed. The ceramic heater according to claim 1, wherein the ceramic heaters are connected with a connected pattern. A pressure roller;
The ceramic heater according to any one of claims 1 to 3, wherein the heating resistor is disposed so as to face the pressure roller.
And a fixing film movably provided between the ceramic substrate and the pressure roller. Image forming means for attaching toner to an electrostatic latent image formed on a medium and further transferring the toner to paper to form an image;
A heating device according to claim 4,
An image forming apparatus, wherein the sheet on which the image is formed is passed through a fixing film while being pressed against the heater by a pressure roller to fix the toner on the sheet.

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