EP3432681B1 - Ceramic heater - Google Patents
Ceramic heater Download PDFInfo
- Publication number
- EP3432681B1 EP3432681B1 EP17766152.7A EP17766152A EP3432681B1 EP 3432681 B1 EP3432681 B1 EP 3432681B1 EP 17766152 A EP17766152 A EP 17766152A EP 3432681 B1 EP3432681 B1 EP 3432681B1
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- EP
- European Patent Office
- Prior art keywords
- wiring portion
- ceramic
- line width
- thickness
- heater
- Prior art date
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- 239000000919 ceramic Substances 0.000 title claims description 250
- 239000011521 glass Substances 0.000 claims description 21
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 20
- 238000000034 method Methods 0.000 claims description 15
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 14
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 claims description 11
- 229910052721 tungsten Inorganic materials 0.000 claims description 11
- 239000010937 tungsten Substances 0.000 claims description 11
- 238000005406 washing Methods 0.000 claims description 10
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 8
- 229910052742 iron Inorganic materials 0.000 claims description 4
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 claims description 3
- 229910052750 molybdenum Inorganic materials 0.000 claims description 3
- 239000011733 molybdenum Substances 0.000 claims description 3
- 238000005476 soldering Methods 0.000 claims description 2
- 230000015556 catabolic process Effects 0.000 description 34
- 230000020169 heat generation Effects 0.000 description 32
- 230000002401 inhibitory effect Effects 0.000 description 16
- 238000005259 measurement Methods 0.000 description 10
- 230000002829 reductive effect Effects 0.000 description 10
- 230000002093 peripheral effect Effects 0.000 description 8
- 238000002844 melting Methods 0.000 description 7
- 230000008018 melting Effects 0.000 description 7
- 238000010586 diagram Methods 0.000 description 6
- 238000010304 firing Methods 0.000 description 6
- 238000004519 manufacturing process Methods 0.000 description 5
- 229910001220 stainless steel Inorganic materials 0.000 description 5
- 239000010935 stainless steel Substances 0.000 description 5
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 4
- 238000001035 drying Methods 0.000 description 4
- 238000002474 experimental method Methods 0.000 description 4
- 229910052751 metal Inorganic materials 0.000 description 4
- 239000002184 metal Substances 0.000 description 4
- 239000002002 slurry Substances 0.000 description 4
- 230000036961 partial effect Effects 0.000 description 3
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 2
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 2
- 230000002411 adverse Effects 0.000 description 2
- 238000005452 bending Methods 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 229910010293 ceramic material Inorganic materials 0.000 description 2
- 238000010344 co-firing Methods 0.000 description 2
- 239000004020 conductor Substances 0.000 description 2
- 229910052593 corundum Inorganic materials 0.000 description 2
- 238000005238 degreasing Methods 0.000 description 2
- 238000007606 doctor blade method Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000012447 hatching Effects 0.000 description 2
- 229910001120 nichrome Inorganic materials 0.000 description 2
- 229910052759 nickel Inorganic materials 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 238000003825 pressing Methods 0.000 description 2
- 238000010792 warming Methods 0.000 description 2
- 229910001845 yogo sapphire Inorganic materials 0.000 description 2
- 229910052582 BN Inorganic materials 0.000 description 1
- PZNSFCLAULLKQX-UHFFFAOYSA-N Boron nitride Chemical compound N#B PZNSFCLAULLKQX-UHFFFAOYSA-N 0.000 description 1
- 229910052581 Si3N4 Inorganic materials 0.000 description 1
- PMHQVHHXPFUNSP-UHFFFAOYSA-M copper(1+);methylsulfanylmethane;bromide Chemical compound Br[Cu].CSC PMHQVHHXPFUNSP-UHFFFAOYSA-M 0.000 description 1
- KZHJGOXRZJKJNY-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Si]=O.O=[Al]O[Al]=O.O=[Al]O[Al]=O.O=[Al]O[Al]=O KZHJGOXRZJKJNY-UHFFFAOYSA-N 0.000 description 1
- 229910052863 mullite Inorganic materials 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 229910052715 tantalum Inorganic materials 0.000 description 1
- GUVRBAGPIYLISA-UHFFFAOYSA-N tantalum atom Chemical compound [Ta] GUVRBAGPIYLISA-UHFFFAOYSA-N 0.000 description 1
Images
Classifications
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B3/00—Ohmic-resistance heating
- H05B3/10—Heating elements characterised by the composition or nature of the materials or by the arrangement of the conductor
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B3/00—Ohmic-resistance heating
- H05B3/40—Heating elements having the shape of rods or tubes
- H05B3/42—Heating elements having the shape of rods or tubes non-flexible
- H05B3/48—Heating elements having the shape of rods or tubes non-flexible heating conductor embedded in insulating material
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B3/00—Ohmic-resistance heating
- H05B3/10—Heating elements characterised by the composition or nature of the materials or by the arrangement of the conductor
- H05B3/18—Heating elements characterised by the composition or nature of the materials or by the arrangement of the conductor the conductor being embedded in an insulating material
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B3/00—Ohmic-resistance heating
- H05B3/20—Heating elements having extended surface area substantially in a two-dimensional plane, e.g. plate-heater
- H05B3/22—Heating elements having extended surface area substantially in a two-dimensional plane, e.g. plate-heater non-flexible
- H05B3/28—Heating elements having extended surface area substantially in a two-dimensional plane, e.g. plate-heater non-flexible heating conductor embedded in insulating material
- H05B3/283—Heating elements having extended surface area substantially in a two-dimensional plane, e.g. plate-heater non-flexible heating conductor embedded in insulating material the insulating material being an inorganic material, e.g. ceramic
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B2203/00—Aspects relating to Ohmic resistive heating covered by group H05B3/00
- H05B2203/013—Heaters using resistive films or coatings
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B2203/00—Aspects relating to Ohmic resistive heating covered by group H05B3/00
- H05B2203/017—Manufacturing methods or apparatus for heaters
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Ceramic Engineering (AREA)
- Inorganic Chemistry (AREA)
- Resistance Heating (AREA)
- Surface Heating Bodies (AREA)
Description
- The present disclosure relates to a ceramic heater for use in a warm water washing toilet seat, a fan heater, an electric water heater, a 24-hour bath, a soldering iron, a hair iron, etc. In particular, the present disclosure relates to a ceramic heater having a structure in which a ceramic sheet having a heater wire is wrapped around an outer periphery of a support member. It also relates to its use, and to its manufacture.
- Generally, a heat exchange unit having a resin container (heat exchanger) is used in a warm water washing toilet seat. A tubular ceramic heater is mounted to the heat exchange unit to warm washing water stored in the heat exchanger.
- As for this type of ceramic heater, a ceramic heater has been known which is formed by wrapping a ceramic sheet, on which a heater wire is printed, around a cylindrical ceramic support member, and integrally firing the ceramic sheet and the support member (e. g., refer to Patent Document 1).
- Patent Document 1:
Japanese Patent No. 3038039 -
JP 2014 163867 A JP 2001 074687 A JP 3 038039 B2 DE 101 00 125 A1 andEP 0 701 979 disclose a ceramic heater according to the preamble of claim 1. - A ceramic heater for a warm water washing toilet seat is used in water at all times, and therefore is hardly energized and heated while it is in a dry state. Meanwhile, when water supply is cut off or piping is in trouble, there is a possibility that the ceramic heater is energized and heated in its dry state. However, since the cross-sectional area (e. g., line width, thickness) of a general heater wire is uniform, if the ceramic heater is heated in its dry state, the heater wire locally generates heat at a wrapping-ends meeting portion of the ceramic sheet, which may cause melting of a glass component present in the ceramic sheet near the heat-generating heater wire. In this case, since electrons become easy to move, partial discharge occurs between a pair of heater wire portions positioned on opposite sides from each other with the wrapping-ends meeting portion therebetween, which may result in dielectric breakdown. Moreover, a ceramic component present in the ceramic sheet is also melted due to a spark that occurs during the partial discharge, which may result in breakage of the ceramic heater.
- According to one aspect of the present disclosure, it is desirable to provide a ceramic heater capable of improving reliability thereof by inhibiting dielectric breakdown that may occur in a heater wire.
- One aspect of the present disclosure is a ceramic heater according to claim 1, including a support member made of ceramic, and a ceramic sheet which is wrapped around an outer periphery of the support member, and includes a heater wire. The heater wire includes a plurality of wiring portions and a connection portion. The plurality of wiring portions include a pair of outer wiring portions, and an inner wiring portion. Each outer wiring portion has a cross-sectional area larger than that of the inner wiring portion.
- The plurality of wiring portions are configured to extend along the axial direction of the support member. The connection portion is configured to connect adjacent wiring portions. The pair of outer wiring portions are disposed on opposite sides from each other with a wrapping-ends meeting portion of the ceramic sheet therebetween. The inner wiring portion is disposed, in the ceramic sheet, between the pair of outer wiring portions.
- In this ceramic heater, the cross-sectional area of each of the pair of outer wiring portions positioned on opposite sides from each other with the wrapping-ends meeting portion of the ceramic sheet therebetween, is set to be larger than the cross-sectional area of the inner wiring portion disposed, in the ceramic sheet, between the pair of outer wiring portions, whereby electric resistance of the outer wiring portion becomes smaller than that of the inner wiring portion. Thus, local heat generation of the heater wire can be suppressed at the wrapping-ends meeting portion where the outer wiring portions are positioned. As a result, melting of a glass component present in the ceramic sheet near the outer wiring portions is suppressed, thereby inhibiting dielectric breakdown between the pair of outer wiring portions, and inhibiting breakage of the ceramic heater. Therefore, reliability of the ceramic heater can be improved.
- As an example of the structure in which the cross-sectional area of the outer wiring portion is larger than that of the inner wiring portion, a structure in which the line width of the outer wiring portion is larger than that of the inner wiring portion is considered. That is, when the line width of each of the pair of outer wiring portions is set to be larger than that of the inner wiring portion, electric resistance of the outer wiring portion becomes smaller than that of the inner wiring portion, whereby local heat generation of the heater wire can be suppressed.
- The line width of the outer wiring portion may be set to be larger than 1.07 times and smaller than 2.4 times the line width of the inner wiring portion. When the line width of the outer wiring portion is set to be larger than 1.07 times the line width of the inner wiring portion, it is possible to suppress local heat generation of the outer wiring portion, and inhibit occurrence of dielectric breakdown between the pair of outer wiring portions positioned on opposite sides from each other with the wrapping-ends meeting portion therebetween. Meanwhile, when the line width of the outer wiring portion is set to be smaller than 2.4 times the line width of the inner wiring portion, it is possible to suppress local temperature reduction in the outer wiring portion, thereby inhibiting reduction in thermal uniformity.
- As an example of the structure in which the cross-sectional area of the outer wiring portion is larger than that of the inner wiring portion, a structure in which the thickness of the outer wiring portion is larger than that of the inner wiring portion is considered. That is, when the thickness of each of the pair of outer wiring portions is set to be larger than that of the inner wiring portion, electric resistance of the outer wiring portion becomes smaller than that of the inner wiring portion.
- The thickness of the outer wiring portion may be set to be larger than 1.25 times and smaller than 2.4 times the thickness of the inner wiring portion. When the thickness of the outer wiring portion is set to be larger than 1.25 times the thickness of the inner wiring portion, it is possible to suppress local heat generation of the outer wiring portion, and inhibit occurrence of dielectric breakdown between the pair of outer wiring portions positioned on opposite sides from each other with the wrapping-ends meeting portion therebetween. Meanwhile, when the thickness of the outer wiring portion is set to be smaller than 2.4 times the thickness of the inner wiring portion, it is possible to suppress local temperature reduction in the outer wiring portion, thereby inhibiting reduction in thermal uniformity.
- A center portion of each outer wiring portion may have a cross-sectional area larger than that of the inner wiring portion.
- The plurality of wiring portions are configured to extend along the axial direction of the support member. The connection portion is configured to connect adjacent wiring portions. The pair of outer wiring portions are disposed on opposite sides from each other with a wrapping-ends meeting portion of the ceramic sheet therebetween. The inner wiring portion is disposed, in the ceramic sheet, between the pair of outer wiring portions.
- In this ceramic heater, the cross-sectional area of the center portion of each of the pair of outer wiring portions positioned on opposite sides from each other with the wrapping-ends meeting portion of the ceramic sheet therebetween, is set to be larger than the cross-sectional area of the inner wiring portion disposed, in the ceramic sheet, between the pair of outer wiring portions, whereby electric resistance of the center portion of the outer wiring portion becomes smaller than that of the inner wiring portion. Thus, local heat generation of the heater wire can be suppressed at the wrapping-ends meeting portion where the outer wiring portions are positioned. As a result, melting of a glass component present in the ceramic sheet near the center portions of the outer wiring portions is suppressed, thereby inhibiting dielectric breakdown between the pair of outer wiring portions, and inhibiting breakage of the ceramic heater. Therefore, reliability of the ceramic heater can be improved.
- As an example of the structure in which the cross-sectional area of the center portion of the outer wiring portion is larger than that of the inner wiring portion, a structure in which the line width of the center portion of the outer wiring portion is larger than that of the inner wiring portion is considered. That is, when the line width of the center portion of each of the pair of outer wiring portions is set to be larger than that of the inner wiring portion, electric resistance of the center portion of the outer wiring portion becomes smaller than that of the inner wiring portion, whereby local heat generation of the heater wire can be suppressed.
- The line width of the center portion may be set to be larger than 1.07 times and not larger than 2.0 times the line width of the inner wiring portion. When the line width of the center portion is set to be larger than 1.07 times the line width of the inner wiring portion, it is possible to suppress local heat generation of the outer wiring portion, and inhibit occurrence of dielectric breakdown between the pair of outer wiring portions positioned on opposite sides from each other with the wrapping-ends meeting portion therebetween. Meanwhile, when the line width of the center portion is set to be not larger than 2.0 times the line width of the inner wiring portion, it is possible to suppress local temperature reduction in the outer wiring portion, thereby inhibiting reduction in thermal uniformity.
- The above-described ceramic heater includes the support member made of ceramic, and the ceramic sheet wrapped around the outer periphery of the support member. Preferred examples of ceramic that forms the support member and the ceramic sheet may include alumina, aluminum nitride, silicon nitride, boron nitride, zirconia, titania, and mullite. In particular, the support member and the ceramic sheet may contain alumina. In this case, a ceramic heater having excellent heat resistance, chemical resistance, and strength can be produced at reduced costs. The ceramic sheet includes a heater element (heater wire) formed of tungsten, molybdenum, tantalum, or the like. The heater wire may contain, as a main component, at least one of tungsten and molybdenum. In this case, the heater wire can be reliably adhered to the ceramic sheet, whereby reliability of the ceramic heater is further improved.
-
- [
FIG. 1 ] Front view of a ceramic heater according to a first embodiment. - [
FIG. 2 ] Plan view showing the ceramic heater according to the first embodiment. - [
FIG. 3 ] Cross-sectional view taken along a line III-III inFIG. 1 . - [
FIG. 4 ] Explanatory diagram showing a developed ceramic sheet according to the first embodiment. - [
FIG. 5] FIGS. 5A, 5B, 5C, and FIG. 5D being explanatory diagrams showing a ceramic heater production method according to the first embodiment. - [
FIG. 6 ] Explanatory diagram showing a developed ceramic sheet according to a second embodiment. - [
FIG. 7 ] Front view of a ceramic heater according to a third embodiment. - [
FIG. 8 ] Plan view showing the ceramic heater according to the third embodiment. - [
FIG. 9 ] Cross-sectional view taken along a line IX-IX inFIG. 7 . - [
FIG. 10 ] Explanatory diagram showing a developed ceramic sheet according to the third embodiment. - [
FIG. 11] FIGS. 11A, 11B, 11C, and 11D being explanatory diagrams showing a ceramic heater production method according to the third embodiment. - [
FIG. 12 ] Cross-sectional view of a major part including portions of a support member and a ceramic sheet according to a fourth embodiment. - [
FIG. 13 ] Explanatory diagram showing a developed ceramic sheet according to the fourth embodiment. - 11...ceramic heater, 17...support member, 19,61...ceramic sheet, 20...wrapping-ends meeting portion, 41,62...heater wire, 44...wiring portion, 45,67...connection portion, 46,63...outer wiring portion, 47,66...inner wiring portion, 64...center portion of outer wiring portion, W1...line width of outer wiring portion, W2,W6...line width of inner wiring portion, W4...line width of center portion, 111...ceramic heater, 117...support member, 119,161...ceramic sheet, 120,168...wrapping-ends meeting portion, 141,162...heater wire, 144...wiring portion, 145,167...connection portion, 146,163...outer wiring portion, 147,166...inner wiring portion, 164...center portion of outer wiring portion, T1...thickness of outer wiring portion, T2,T4...thickness of inner wiring portion, T3...thickness of center portion
- Hereinafter, a ceramic heater and a production method therefor according to a first embodiment of the present disclosure will be described with reference to the drawings.
- A
ceramic heater 11 according to the present embodiment is used in, for example, a heat exchanger of a heat exchange unit of a warm water washing toilet seat, for the purpose of warming washing water. - As shown in
FIGS. 1 and2 , theceramic heater 11 includes: a cylindricalceramic heater body 13 made of ceramic; and anannular flange 15 made of metal, externally fitted to theheater body 13. Theflange 15 is an annular member formed by bending a metal plate such as a stainless-steel plate. Theflange 15 has a recessed (cup-shaped) center portion. - In the present embodiment, as shown in
FIG. 2 , in the recessed portion of theflange 15, a space surrounded by an outerperipheral surface 14 of theheater body 13 and an inner surface of theflange 15 serves as aglass reservoir 35. Theglass reservoir 35 is filled withglass 33, and theheater body 13 and theflange 15 are welded and fixed via theglass 33. InFIG. 2 , theglass 33 is shown by hatching. - As shown in
FIGS. 1 to 3 , theheater body 13 is composed of: acylindrical support member 17 made of ceramic; and aceramic sheet 19 wrapped around the outer periphery of thesupport member 17. In the present embodiment, thesupport member 17 and theceramic sheet 19 are formed by using ceramic such as alumina (Al2O3). The thermal expansion coefficient of alumina is within a range of 50×10-7/K to 90×10-7/K, and is 70×10-7/K (30°C to 380°C) in the present embodiment. In the present embodiment, thesupport member 17 has an outer diameter set to 12 mm, an inner diameter set to 8 mm, and a length set to 65 mm. Theceramic sheet 19 has a thickness set to 0.5 mm, and a length set to 60 mm. Theceramic sheet 19 does not completely cover the outer periphery of thesupport member 17. Therefore, aslit 21 is formed at a wrapping-ends meeting portion 20 of theceramic sheet 19. Theslit 21 extends along an axial direction of thesupport member 17, and exposes an outer peripheral surface of thesupport member 17. Theslit 21 of the present embodiment has a width set to 1 mm, and a depth set to 0.5 mm. - As shown in
FIGS. 3 and4 , inside theceramic sheet 19, aheater wire 41 having a meandering pattern and a pair ofinternal terminals 42 are formed. In the present embodiment, theheater wire 41 and theinternal terminals 42 contain tungsten (W) as a main component. Theinternal terminals 42 are electrically connected to external terminals 43 (refer toFIG. 1 ) formed on an outer peripheral surface of theceramic sheet 19, through via conductors (not shown) or the like. - The
heater wire 41 includes: a plurality ofwiring portions 44 extending along the axial direction of thesupport member 17; andconnection portions 45 each connectingadjacent wiring portions 44 to each other. The plurality ofwiring portions 44 include a pair ofouter wiring portions 46, and a plurality ofinner wiring portions 47. The pair ofouter wiring portions 46 are disposed on opposite sides from each other with the wrapping-ends meeting portion 20 (refer toFIG. 3 ) of theceramic sheet 19 therebetween. A first end (upper end inFIG. 4 ) of eachouter wiring portion 46 is connected to aninternal terminal 42, and a second end (lower end inFIG. 4 ) of theouter wiring portion 46 is connected to aninner wiring portion 47 via aconnection portion 45. Theinternal terminals 42 are disposed between the pair ofouter wiring portions 46 when theceramic sheet 19 is viewed in the thickness direction. - As shown in
FIGS. 3 and4 , in theceramic sheet 19, theinner wiring portions 47 are disposed between the pair ofouter wiring portions 46. A first end (upper end inFIG. 4 ) of eachinner wiring portion 47 is connected to a first end of an adjacentinner wiring portion 47 via aconnection portion 45. A second end (lower end inFIG. 4 ) of eachinner wiring portion 47 is connected to a second end of an adjacentinner wiring portion 47 or to a second end of an adjacentouter wiring portion 46, via aconnection portion 45. - Each
outer wiring portion 46 of the present embodiment has a line width W1 set to 0.66 mm and a thickness set to 15 µm. Eachinner wiring portion 47 of the present embodiment has a line width W2 set to 0.60 mm and a thickness set to 15 µm. Likewise, eachconnection portion 45 of the present embodiment has a line width W3 set to 0.60 mm and a thickness set to 15 µm. That is, the line width W1 of theouter wiring portion 46 is larger than the line width W2 of theinner wiring portion 47 and the line width W3 of theconnection portion 45. Specifically, the line width W1 of theouter wiring portion 46 is set to be 1.1 times the line width W2 of theinner wiring portion 47 and the line width W3 of theconnection portion 45. The line width W2 of theinner wiring portion 47 is equal to the line width W3 of theconnection portion 45. Since the thickness of theouter wiring portion 46 is equal to the thickness of theinner wiring portion 47 and to the thickness of theconnection portion 45, the cross-sectional area of theouter wiring portion 46 is larger than the cross-sectional area of theinner wiring portion 47 and the cross-sectional area of theconnection portion 45. - Next, a method of producing the
ceramic heater 11 of the present embodiment will be described. - First, a clayey slurry containing alumina as a main component is put in a conventionally known extruder (not shown), and the slurry is molded into a tubular member. Then, the molded tubular member is dried, and thereafter is subjected to pre-firing in which the cylindrical member is heated to a predetermined temperature (e. g., about 1000°C), thereby obtaining the support member 17 (refer to
FIG. 5A ). - Using a ceramic material containing alumina powder as a main component, first and second ceramic
green sheets ceramic sheet 19, are formed. As for a method of forming the ceramic green sheets, a known formation method such as a doctor blade method can be adopted. Then, using a conventionally known paste printing apparatus (not shown), a conductive paste (tungsten paste in the present embodiment) is printed on the surface of the first ceramicgreen sheet 51. As a result, anunfired electrode 53, which will become theheater wire 41 and theinternal terminals 42, is formed on the surface of the first ceramic green sheet 51 (refer toFIG. 5B ). The line width of theunfired electrode 53 is adjusted to be, for example, a width obtained by adding an amount of shrinkage at firing to the line width of theheater wire 41. - After drying of the conductive paste, the second ceramic
green sheet 52 is stacked on the printed surface (surface on which theunfired electrode 53 is formed) of the first ceramicgreen sheet 51, and a pressing force is applied in the sheet stacking direction. As a result, the ceramicgreen sheets FIG. 5C ). Further, using the paste printing apparatus, a conductive paste is printed on the surface of the second ceramicgreen sheet 52. As a result, anunfired electrode 55, which will become theexternal terminals 43, is formed on the surface of the second ceramicgreen sheet 52. - Next, a ceramic paste (alumina paste) is applied to one side of the green-sheet stacked
body 54, and the green-sheet stackedbody 54 is wrapped around the outer peripheral surface of thesupport member 17 so as to be adhered to the support member 17 (refer toFIG. 5D ). At this time, the size of the green-sheet stackedbody 54 is adjusted so that the opposing ends of the green-sheet stackedbody 54 do not overlap each other. Next, a drying process, a degreasing process, etc. are performed according to conventionally known techniques, and thereafter, co-firing is performed in which the green-sheet stacked body 54 (the ceramicgreen sheets unfired electrodes 53 and 55) is heated to a predetermined temperature (e. g., about 1400°C to 1600°C) at which alumina and tungsten in the green-sheet stackedbody 54 can be sintered. As a result, alumina in the ceramicgreen sheets body 54 becomes theceramic sheet 19, theunfired electrode 53 becomes theheater wire 41 and theinternal terminals 42, and theunfired electrode 55 becomes theexternal terminals 43. Thereafter, theexternal terminals 43 are plated with nickel to obtain theheater body 13. - Next, a plate member made of stainless steel is press-formed using a die, thereby forming the cup-shaped
flange 15. Then, theflange 15 is externally fitted to theheater body 13 at a predetermined position. Thereafter, theheater body 13 and theflange 15 are welded and fixed via theglass 33 to complete theceramic heater 11. - Hereinafter, an example of an experiment performed to evaluate the performance of the
ceramic heater 11 of the present embodiment will be described. - First, measurement samples were prepared as follows. A ceramic heater was prepared which includes a ceramic sheet having a line width of each outer wiring portion being 0.60 mm, a line width of each inner wiring portion being 0.60 mm, and a value of a ratio of the line width of the outer wiring portion to the line width of the inner wiring portion being 1.0. In other words, a ceramic heater in which the line width of each outer wiring portion was equal to the line width of each inner wiring portion was prepared. This ceramic heater was regarded as a sample 1A. Further, a ceramic heater having a line width of each outer wiring portion being 0.64 mm, a line width of each inner wiring portion being 0.60 mm, and a value of the ratio being 1.07 was prepared as a sample 1B. A ceramic heater having a line width of each outer wiring portion being 0.60 mm, a line width of each inner wiring portion being 0.55 mm, and a value of the ratio being 1.09 was prepared as a sample 1C. A ceramic heater having a line width of each outer wiring portion being 0.66 mm, a line width of each inner wiring portion being 0.60 mm, and a value of the ratio being 1.1, that is, a ceramic heater identical to the
ceramic heater 11 of the present embodiment, was prepared as a sample 1D. A ceramic heater having a line width of each outer wiring portion being 0.69 mm, a line width of each inner wiring portion being 0.60 mm, and a value of the ratio being 1.15 was prepared as a sample 1E. A ceramic heater having a line width of each outer wiring portion being 1.20 mm, a line width of each inner wiring portion being 0.60 mm, and a value of the ratio being 2.0 was prepared as a sample 1F. A ceramic heater having a line width of each outer wiring portion being 1.44 mm, a line width of each inner wiring portion being 0.60 mm, and a value of the ratio being 2.4 was prepared as a sample 1G. As for each of the samples 1A to 1G, five samples were prepared. - Next, a nichrome wire was soldered to a pair of internal terminals (heater wire) included in the ceramic sheet of each of the measurement samples (samples 1A to 1G), and each measurement sample, in its dry state, was placed on a base. Then, a voltage (AC 240V) was applied across the pair of internal terminals for 6 minutes, and the surface temperature of the ceramic sheet was measured by a thermocamera. In addition, it was observed whether local heat generation occurred at the outer wiring portions and whether dielectric breakdown occurred between the pair of outer wiring portions. If dielectric breakdown occurred, the occurrence time was measured and recorded. The results are shown on Table 1.
[Table 1] Sample Line width Test result Outer wiring portion (W1) Inner wiring portion (W2) Ratio (W1/W2) Local heat generation Dielectric breakdown 1A 0.60 mm 0.60 mm 1.0 5/5 5/5 1B 0.64 mm 0.60 mm 1.07 5/5 2/5 1C 0.60 mm 0.55 mm 1.09 0/5 0/5 1D 0.66 mm 0.60 mm 1.1 0/5 0/5 1E 0.69 mm 0.60 mm 1.15 0/5 0/5 1F 1.20 mm 0.60 mm 2.0 0/5 0/5 1G 1.44 mm 0.60 mm 2.4 0/5 0/5 - According to the results, as for the sample 1A, it was found that, in all the five samples, local heat generation occurred, and dielectric breakdown occurred with a spark after 1 min and 50 sec had passed. As for the sample 1B, it was found that local heat generation occurred in all the five samples, and dielectric breakdown occurred in two samples among the five samples. Meanwhile, as for samples 1C to 1G, neither local heat generation nor dielectric breakdown was found in any of the five samples throughout observation for 6 minutes. However, as for the sample 1G, it was found that the temperature at the wrapping-ends meeting portion of the ceramic sheet was reduced, leading to reduction in thermal uniformity.
- From the above, it was verified that local heat generation and dielectric breakdown are not likely to occur and thermal uniformity is not likely to be reduced if the line width of each of the pair of outer wiring portions positioned on opposite sides from each other with the wrapping-ends meeting portion therebetween is set to be not smaller than 1.09 times and not larger than 2.0 times the line width of each inner wiring portion disposed between the pair of outer wiring portions.
- Therefore, the following effects can be achieved according to the present embodiment.
- (1) In the
ceramic heater 11 of the present embodiment, when the line width W1 of eachouter wiring portion 46 is larger than the line width W2 of eachinner wiring portion 47, electric resistance of theouter wiring portion 46 becomes smaller than that of theinner wiring portion 47. Therefore, at the wrapping-ends meeting portion 20 where theouter wiring portions 46 are positioned, local heat generation of theheater wire 41 can be suppressed. As a result, melting of the glass component present in theceramic sheet 19 near theouter wiring portions 46 is suppressed, thereby inhibiting dielectric breakdown between the pair ofouter wiring portions 46, and inhibiting breakage of theceramic heater 11. Thus, reliability of theceramic heater 11 can be improved. - (2) In the present embodiment, the pair of
internal terminals 42 formed in theceramic sheet 19 are disposed inward of the pair ofouter wiring portions 46 also formed in the ceramic sheet 19 (refer toFIG. 4 ). Therefore, when theceramic sheet 19 is wrapped around the outer periphery of thesupport member 17, theinternal terminals 42 are positioned on opposite sides from each other in the radial direction of thesupport member 17. As a result, the distance between theinternal terminals 42 is increased, whereby occurrence of discharge between theinternal terminals 42 can be suppressed. - Hereinafter, a second embodiment of the present disclosure will be described with reference to the drawings. The following description focuses on a difference from the first embodiment. In the present embodiment, the structure of the heater wire is different from that of the first embodiment.
- Specifically, as shown in a
ceramic sheet 61 ofFIG. 6 , each ofouter wiring portions 63 as components of aheater wire 62 has: a line width W4, at acenter portion 64, set to 0.66 mm; a line width W5, at aportion 65 other than thecenter portion 64, set to 0.60 mm; and a thickness set to 15 µm. The "center portion 64 of theouter wiring portion 63" is a region, of a center portion of theouter wiring portion 63, which occupies not larger than one-third of the length of theouter wiring portion 63. Further, each ofinner wiring portions 66 as components of theheater wire 62 has a line width W6 set to 0.60 mm, and a thickness set to 15 µm. Further, each ofconnection portions 67 as components of theheater wire 62 also has a line width W7 set to 0.60 mm, and a thickness set to 15 µm. That is, the line width W4 of thecenter portion 64 of theouter wiring portion 63 is larger than the line width W5 of theother portion 65 of theouter wiring portion 63, the line width W6 of theinner wiring portion 66, and the line width W7 of theconnection portion 67. Specifically, the line width W4 of thecenter portion 64 is set to be 1.1 times the line width W5 of theother portion 65, the line width W6 of theinner wiring portion 66, and the line width W7 of theconnection portion 67. Since the thickness of thecenter portion 64 is equal to the thickness of theother portion 65, the thickness of theinner wiring portion 66, and the thickness of theconnection portion 67, the cross-sectional area of thecenter portion 64 is larger than the cross-sectional area of theother portion 65, the cross-sectional area of theinner wiring portion 66, and the cross-sectional area of theconnection portion 67. In a connection portion between thecenter portion 64 and theother portion 65, the line width of theouter wiring portion 63 gradually increases from theother portion 65 to thecenter portion 64. - Hereinafter, an example of an experiment performed to evaluate the performance of the ceramic heater of the present embodiment will be described.
- First, measurement samples were prepared as follows. A ceramic heater was prepared which includes a ceramic sheet having a line width of the center portion of each outer wiring portion being 0.60 mm, a line width of each inner wiring portion being 0.55 mm, and a value of a ratio of the line width of the center portion to the line width of the inner wiring portion being 1.09. This ceramic heater was regarded as a sample 1C'. Further, a ceramic heater having a line width of the center portion being 0.66 mm, a line width of each inner wiring portion being 0.60 mm, and a value of the ratio being 1.1, that is, a ceramic heater identical to the ceramic heater of the present embodiment, was prepared as a sample 1D'. A ceramic heater having a line width of the center portion being 0.69 mm, a line width of each inner wiring portion being 0.60 mm, and a value of the ratio being 1.15 was prepared as a sample 1E'. A ceramic heater having a line width of the center portion being 1.20 mm, a line width of each inner wiring portion being 0.60 mm, and a value of the ratio being 2.0 was prepared as a sample 1F'. As for each of the samples 1C' to 1F', five samples were prepared.
- Next, a voltage (AC 240V) was applied across a pair of internal terminals included in each of the measurement samples (samples 1C' to 1F') for 6 minutes, and the surface temperature of the ceramic sheet was measured by a thermocamera. In addition, it was observed whether local heat generation occurred at the outer wiring portions and whether dielectric breakdown occurred between the pair of outer wiring portions. The results are shown on Table 2.
[Table 2] Sample Line width Examination result Center portion (W4) Inner wiring portion (W6) Ratio (W4/W6) Local heat generation Dielectric breakdown 1C' 0.60 mm 0.55 mm 1.09 0/5 0/5 1D' 0.66 mm 0.60 mm 1.1 0/5 0/5 1E' 0.69 mm 0.60 mm 1.15 0/5 0/5 1F' 1.20 mm 0.60 mm 2.0 0/5 0/5 - According to the results, as for the samples 1C' to 1F', neither local heat generation nor dielectric breakdown was found in any of the five samples throughout observation for 6 minutes. As for the samples 1D' and 1E', the temperature of the center portion of each outer wiring portion was reduced a little, but it was found that this reduction in temperature did not adversely affect thermal uniformity of the ceramic sheet.
- From the above, it was verified that local heat generation and dielectric breakdown are not likely to occur and thermal uniformity is not likely to be reduced if the line width of the center portion of each of the pair of outer wiring portions positioned on opposite sides from each other with the wrapping-ends meeting portion therebetween is set to be not smaller than 1.09 times and not larger than 2.0 times the line width of each inner wiring portion disposed between the pair of outer wiring portions.
- According to the present embodiment, when the line width W4 of the
center portion 64 of eachouter wiring portion 63 is larger than the line width W6 of eachinner wiring portion 66, electric resistance of thecenter portion 64 becomes smaller than that of theinner wiring portion 66. Therefore, at the wrapping-ends meeting portion of theceramic sheet 61 where theouter wiring portions 63 are positioned, local heat generation of theheater wire 62 can be suppressed. As a result, melting of the glass component present in theceramic sheet 61 near thecenter portions 64 of theouter wiring portions 63 is suppressed, thereby inhibiting dielectric breakdown between the pair ofouter wiring portions 63, and inhibiting breakage of the ceramic heater. Therefore, reliability of the ceramic heater can be improved. - Hereinafter, a ceramic heater and a production method therefor according to a third embodiment of the present disclosure will be described with reference to the drawings.
- A
ceramic heater 111 according to the present embodiment is used in, for example, a heat exchanger of a heat exchange unit of a warm water washing toilet seat, for the purpose of warming washing water. - As shown in
FIGS. 7 and8 , theceramic heater 111 includes: a cylindricalceramic heater body 113 made of ceramic; and anannular flange 115 made of metal, externally fitted to theheater body 113. Theflange 115 is an annular member formed by bending a metal plate such as a stainless-steel plate. Theflange 115 has a recessed (cup-shaped) center portion. - In the present embodiment, as shown in
FIG. 8 , in the recessed portion of theflange 115, a space surrounded by an outerperipheral surface 114 of theheater body 113 and an inner surface of theflange 115 serves as aglass reservoir 135. Theglass reservoir 135 is filled withglass 133, and theheater body 113 and theflange 115 are welded and fixed via theglass 133. InFIG. 8 , theglass 133 is shown by hatching. - As shown in
FIGS. 7 to 9 , theheater body 113 is composed of: acylindrical support member 117 made of ceramic; and aceramic sheet 119 wrapped around the outer periphery of thesupport member 117. In the present embodiment, thesupport member 117 and theceramic sheet 119 are formed by using ceramic such as alumina (Al2O3). The thermal expansion coefficient of alumina is within a range of 50×10-7/K to 90×10-7/K, and is 70×10-7/K (30°C to 380°C) in the present embodiment. In the present embodiment, thesupport member 117 has an outer diameter set to 12 mm, an inner diameter set to 8 mm, and a length set to 65 mm. Theceramic sheet 119 has a thickness set to 0.5 mm, and a length set to 60 mm. Theceramic sheet 119 does not completely cover the outer periphery of thesupport member 117. Therefore, aslit 121 is formed at a wrapping-ends meeting portion 120 of theceramic sheet 119. Theslit 121 extends along an axial direction of thesupport member 117, and exposes an outer peripheral surface of thesupport member 117. Theslit 121 of the present embodiment has a width set to 1 mm, and a depth set to 0.5 mm. - As shown in
FIGS. 9 and10 , inside theceramic sheet 119, aheater wire 141 having a meandering pattern and a pair ofinternal terminals 142 are formed. In the present embodiment, theheater wire 141 and theinternal terminals 142 contain tungsten (W) as a main component. Theinternal terminals 142 are electrically connected to external terminals 143 (refer toFIG. 7 ) formed on an outer peripheral surface of theceramic sheet 119, through via conductors (not shown) or the like. - The
heater wire 141 includes: a plurality ofwiring portions 144 extending along the axial direction of thesupport member 117; andconnection portions 145 each connectingadjacent wiring portions 144 to each other. Thewiring portions 144 include a pair ofouter wiring portions 146, and a plurality ofinner wiring portions 147. Theouter wiring portions 146 are disposed on opposite sides from each other with a wrapping-ends meeting portion 120 (refer toFIG. 9 ) of theceramic sheet 119 therebetween. A first end (upper end inFIG. 10 ) of eachouter wiring portion 146 is connected to aninternal terminal 142, and a second end (lower end inFIG. 10 ) of eachouter wiring portion 146 is connected to aninner wiring portion 147 via aconnection portion 145. Theinternal terminals 142 are disposed between the pair ofouter wiring portions 146 when theceramic sheet 119 is viewed in the thickness direction. - As shown in
FIGS. 9 and10 , in theceramic sheet 119, theinner wiring portions 147 are disposed between the pair ofouter wiring portions 146. A first end (upper end inFIG. 10 ) of eachinner wiring portion 147 is connected to a first end of an adjacentinner wiring portion 147 via aconnection portion 145. A second end (lower end inFIG. 10 ) of eachinner wiring portion 147 is connected to a second end of an adjacentinner wiring portion 147 or to a second end of an adjacentouter wiring portion 146, via aconnection portion 145. - Each
outer wiring portion 146 of the present embodiment has a thickness T1 set to 20 µm, and a line width set to 0.60 mm. Eachinner wiring portion 147 of the present embodiment has a thickness T2 set to 15 µm, and a line width set to 0.60 mm. Likewise, eachconnection portion 145 of the present embodiment has a thickness set to 15 µm, and a line width set to 0.60 mm. That is, the thickness T1 of theouter wiring portion 146 is larger than the thickness T2 of theinner wiring portion 147 and the thickness of theconnection portion 145. Specifically, the thickness T1 of theouter wiring portion 146 is set to be 1.33 times the thickness T2 of theinner wiring portion 147 and the thickness of theconnection portion 145. The thickness T2 of theinner wiring portion 147 is equal to the thickness of theconnection portion 145. Since the line width of theouter wiring portion 146 is equal to the line width of theinner wiring portion 147 and to the line width of theconnection portion 145, the cross-sectional area of theouter wiring portion 146 is larger than the cross-sectional area of theinner wiring portion 147 and the cross-sectional area of theconnection portion 145. - Next, a method of producing the
ceramic heater 111 of the present embodiment will be described. - First, a clayey slurry containing alumina as a main component is put in a conventionally known extruder (not shown), and the slurry is molded into a tubular member. Then, the molded tubular member is dried, and thereafter is subjected to pre-firing in which the cylindrical member is heated to a predetermined temperature (e. g., about 1000°C), thereby obtaining the support member 117 (refer to
FIG. 11A ). - Using a ceramic material containing alumina powder as a main component, first and second ceramic
green sheets ceramic sheet 119, are formed. As for a method of forming the ceramic green sheets, a known formation method such as a doctor blade method can be adopted. - Then, a printing process is performed by using a conventionally known paste printing apparatus (not shown), to print a conductive paste (tungsten paste in the present embodiment) on the surface of the first ceramic
green sheet 151. In the present embodiment, the conductive paste is printed dividedly in two times to make the thickness T1 of theouter wiring portion 146 larger than the thickness T2 of theinner wiring portion 147. Specifically, first, the conductive paste is printed on the surface of the first ceramicgreen sheet 151, thereby forming afirst electrode 153 as an unfired electrode which forms theheater wire 141 and the internal terminals 142 (refer toFIG. 11B ). The line width of thefirst electrode 153 is adjusted to be, for example, a width obtained by adding an amount of shrinkage at firing to the line width of theheater wire 141. Next, the conductive paste is printed on portions, of thefirst electrode 153, which will become theouter wiring portions 146, thereby forming asecond electrode 154 which forms portions of the outer wiring portions 146 (refer toFIG. 11B ). Although not shown, the line width of thesecond electrode 154 is adjusted to be narrower than that of thefirst electrode 153, for example. - After drying of the conductive paste, a second ceramic
green sheet 152 is stacked on the printed surface (surface on which thefirst electrode 153 and thesecond electrode 154 are formed) of the first ceramicgreen sheet 151, and a pressing force is applied in the sheet stacking direction. As a result, the ceramicgreen sheets FIG. 11C ). Further, using the paste printing apparatus, the conductive paste is printed on the surface of the second ceramicgreen sheet 152. As a result, anunfired electrode 156, which will become theexternal terminals 143, is formed on the surface of the second ceramicgreen sheet 152. - Next, a wrapping process is performed in which a ceramic paste (alumina paste) is applied to one side of the green-sheet
stacked body 155, and the green-sheetstacked body 155 is wrapped around the outer peripheral surface of thesupport member 117 so as to be adhered to the support member 117 (refer toFIG. 11D ). At this time, the size of the green-sheetstacked body 155 is adjusted so that the opposing ends of the green-sheetstacked body 155 do not overlap each other. Next, a drying process, a degreasing process, etc. are performed according to conventionally known techniques, and thereafter, co-firing is performed in which the green-sheet stacked body 155 (the ceramicgreen sheets first electrode 153, thesecond electrode 154, and the unfired electrode 156) is heated to a predetermined temperature (e. g., about 1400°C to 1600°C) at which alumina and tungsten in the green-sheetstacked body 155 can be sintered. As a result, alumina in the ceramicgreen sheets stacked body 155 becomes theceramic sheet 119, theelectrodes heater wire 141 and theinternal terminal 142, respectively, and theunfired electrode 156 becomes theexternal terminals 143. Thereafter, theexternal terminals 143 are plated with nickel to obtain theheater body 113. - Next, a plate member made of stainless steel is press-formed using a die, thereby forming the cup-shaped
flange 115. Then, theflange 115 is externally fitted to theheater body 113 at a predetermined position. Thereafter, theheater body 113 and theflange 115 are welded and fixed via theglass 133 to complete theceramic heater 111. - Hereinafter, an example of an experiment performed to evaluate the performance of the
ceramic heater 111 of the present embodiment will be described. - First, measurement samples were prepared as follows. A ceramic heater was prepared which includes a ceramic sheet having a thickness of each outer wiring portion being 15 µm, a thickness of each inner wiring portion being 15 µm, and a value of a ratio of the thickness of the outer wiring portion to the thickness of the inner wiring portion being 1.0. In other words, a ceramic heater in which the thickness of each outer wiring portion is equal to the thickness of each inner wiring portion was prepared. This ceramic heater was regarded as a sample 2A. Further, a ceramic heater having a thickness of each outer wiring portion being 18 µm, a thickness of each inner wiring portion being 15 µm, and a value of the ratio being 1.2 was prepared as a sample 2B. A ceramic heater having a thickness of each outer wiring portion being 15 µm, a thickness of each inner wiring portion being 12 µm, and a value of the ratio being 1.25 was prepared as a sample 2C. A ceramic heater having a thickness of each outer wiring portion being 19 µm, a thickness of each inner wiring portion being 15 µm, and a value of the ratio being 1.27 was prepared as a sample 2D. A ceramic heater having a thickness of each outer wiring portion being 20 µm, a thickness of each inner wiring portion being 15 µm, and a value of the ratio being 1.33, that is, a ceramic heater identical to the
ceramic heater 111 of the present embodiment, was prepared as a sample 2E. A ceramic heater having a thickness of the outer wiring portion being 25 µm, a thickness of the inner wiring portion being 15 µm, and a value of the ratio being 1.67 was prepared as a sample 2F. A ceramic heater having a thickness of each outer wiring portion being 30 µm, a thickness of each inner wiring portion being 15 µm, and a value of the ratio being 2.0 was prepared as a sample 2G. A ceramic heater having a thickness of each outer wiring portion being 36 µm, a thickness of each inner wiring portion being 15 µm, and a value of the ratio being 2.4 was prepared as a sample 2H. As for each of the samples 2A to 2H, five samples were prepared. - Next, a nichrome wire was soldered to a pair of internal terminals (heater wire) included in the ceramic sheet of each of the measurement samples (samples 2A to 2H), and each measurement sample, in its dry state, was placed on a base. Then, a voltage (AC 240V) was applied across the pair of internal terminals for 6 minutes, and the surface temperature of the ceramic sheet was measured by a thermocamera. In addition, it was observed whether local heat generation occurred at the outer wiring portions and whether dielectric breakdown occurred between the pair of outer wiring portions. If dielectric breakdown occurred, the occurrence time was measured and recorded. The results are shown on Table 3.
[Table 3] Sample Thickness Test result Outer wiring portion (T1) Inner wiring portion (T2) Ratio(T1/T2) Local heat generation Dielectric breakdown 2A 15 µm 15 µm 1.0 5/5 5/5 2B 18 µm 15 µm 1.2 5/5 2/5 2C 15 µm 12 µm 1.25 1/5 0/5 2D 19 µm 15 µm 1.27 0/5 0/5 2E 20 µm 15 µm 1.33 0/5 0/5 2F 25 µm 15 µm 1.67 0/5 0/5 2G 30 µm 15 µm 2.0 0/5 0/5 2H 36 µm 15 µm 2.4 0/5 0/5 - According to the results, as for the sample 2A, it was found that, in all the five samples, local heat generation occurred, and dielectric breakdown occurred with a spark after 1 min and 50 sec had passed. As for the sample 2B, it was found that local heat generation occurred in all the five samples, and dielectric breakdown occurred in two samples among the five samples. As for the sample 2C, occurrence of dielectric breakdown was not found, but local heat generation was found in one sample among the five samples. Meanwhile, as for the samples 2D to 2H, neither local heat generation nor dielectric breakdown was found in any of the five samples throughout observation for 6 minutes. However, in the sample 2H, it was found that the temperature at the wrapping-ends meeting portion of the ceramic sheet was reduced, leading to reduction in thermal uniformity.
- From the above, it was verified that local heat generation and dielectric breakdown are not likely to occur and thermal uniformity is not likely to be reduced if the thickness of each of the pair of outer wiring portions positioned on opposite sides from each other with the wrapping-ends meeting portion therebetween is set to be not smaller than 1.27 times and not larger than 2.0 times the thickness of each inner wiring portion disposed between the pair of outer wiring portions.
- Therefore, the following effects can be achieved according to the present embodiment.
- (1) In the
ceramic heater 111 of the present embodiment, since the thickness T1 of eachouter wiring portion 146 is larger than the thickness T2 of eachinner wiring portion 147, electric resistance of theouter wiring portion 146 becomes smaller than that of theinner wiring portion 147. Therefore, at the wrapping-ends meeting portion 120 where theouter wiring portions 146 are positioned, local heat generation of theheater wire 141 can be suppressed. As a result, melting of the glass component present in theceramic sheet 119 near theouter wiring portions 146 is suppressed, thereby inhibiting dielectric breakdown between the pair ofouter wiring portions 146, and inhibiting breakage of theceramic heater 111. Thus, reliability of theceramic heater 111 can be improved. - (2) In the present embodiment, the pair of
internal terminals 142 formed in theceramic sheet 119 are disposed inward of the pair ofouter wiring portions 146 also formed in the ceramic sheet 119 (refer toFIG. 10 ). Therefore, when theceramic sheet 119 is wrapped around the outer periphery of thesupport member 117, theinternal terminals 142 are positioned on opposite sides from each other in the radial direction of thesupport member 117. As a result, the distance between theinternal terminals 142 is increased, whereby occurrence of discharge between theinternal terminals 142 can be suppressed. - (3) In the present embodiment, since the electric resistance of each
outer wiring portion 146 is reduced without increasing the width of theouter wiring portion 146. Therefore, it is easy to ensure the distance between the pair ofouter wiring portions 146 disposed on opposite sides from each other with the wrapping-ends meeting portion 120 therebetween. Accordingly, occurrence of partial discharge between theouter wiring portions 146 can be suppressed more reliably. - Hereinafter, a fourth embodiment of the present disclosure will be described with reference to the drawings. The following description focuses on a difference from the third embodiment. In the present embodiment, the structure of the heater wire is different from that of the third embodiment.
- Specifically, as shown in
FIGS. 12 and13 , each ofouter wiring portions 163 as components of aheater wire 162 included in aceramic sheet 161, has: a thickness T3, of acenter portion 164, set to 20 µm; a thickness, of aportion 165 other than thecenter portion 164, set to 15 µm; and a line width set to 0.60 mm. The "center portion 164 of theouter wiring portion 163" is a region, of a center portion of theouter wiring portion 163, which occupies not larger than one-third of the length of theouter wiring portion 163. Each ofinner wiring portions 166 as components of theheater wire 162 has a thickness T4 set to 15 µm, and a line width set to 0.60 mm. Further, each ofconnection portions 167 as components of theheater wire 162 also has a thickness set to 15 µm, and a line width set to 0.60 mm. That is, the thickness T3 of thecenter portion 164 of theouter wiring portion 163 is larger than the thickness of theother portion 165 of theouter wiring portion 163, the thickness T4 of theinner wiring portion 166, and the thickness of theconnection portion 167. Specifically, the thickness T3 of thecenter portion 164 is set to be 1.33 times the thickness of theother portion 165, the thickness T4 of theinner wiring portion 166, and the thickness of theconnection portion 167. Since the line width of thecenter portion 164 is equal to the line width of theother portion 165, the line width of theinner wiring portion 166, and the line width of theconnection portion 167, the cross-sectional area of thecenter portion 164 is larger than the cross-sectional area of theother portion 165, the cross-sectional area of theinner wiring portion 166, and the cross-sectional area of theconnection portion 167. - In the present embodiment, the conductive paste is printed dividedly in two times, to make the thickness T3 of the
center portion 164 larger than the thickness T4 of theinner wiring portion 166. Specifically, first, the conductive paste is printed on the surface of a ceramic green sheet which will become theceramic sheet 161, thereby forming a first electrode as an unfired electrode which forms theheater wire 162. Next, the conductive paste is printed on portions, of the first electrode, which will become thecenter portions 164, thereby forming a second electrode which form portions of thecenter portions 164. Although not shown, the line width of the second electrode is adjusted so as to be narrower than that of the first electrode, for example. Thereafter, a firing process is performed, whereby the ceramic green sheet becomes theceramic sheet 161, portions of the region where the first electrode is formed become theinner wiring portions 166, and the regions where the first and second electrodes are formed become thecenter portions 164 thicker than theinner wiring portions 166. - Hereinafter, an example of an experiment performed to evaluate the performance of the ceramic heater of the present embodiment will be described.
- First, measurement samples were prepared as follows. A ceramic heater was prepared which includes a ceramic sheet having a thickness of the center portion of each outer wiring portion being 15 µm, a thickness of each inner wiring portion being 12 µm, and a value of a ratio of the thickness of the center portion to the thickness of the inner wiring portion being 1.25. This ceramic heater was regarded as a sample 2C'. Further, a ceramic heater having a thickness of the center portion being 20 µm, a thickness of each inner wiring portion being 15 µm, and a value of the ratio being 1.33, that is, a ceramic heater identical to the ceramic heater of the present embodiment, was prepared as a sample 2E'. A ceramic heater having a thickness of the center portion being 25 µm, a thickness of each inner wiring portion being 15 µm, and a value of the ratio being 1.67 was prepared as a sample 2F'. A ceramic heater having a thickness of the center portion being 30 µm, a thickness of each inner wiring portion being 15 µm, and a value of the ratio being 2.0 was prepared as a sample 2G'. As for each of the samples 2C', 2E' to 2G', five samples were prepared.
- Next, a voltage (AC 240V) was applied across a pair of internal terminals included in each of the measurement samples (samples 2C', 2E' to 2G') for 6 minutes, and the surface temperature of the ceramic sheet was measured by a thermocamera. In addition, it was observed whether local heat generation occurred at the outer wiring portions and whether dielectric breakdown occurred between the pair of outer wiring portions. The results are shown on Table 4.
[Table 4] Sample Thickness Test result Center portion (T3) Inner wiring portion (T4) Ratio (T3/T4) Local heat generation Dielectric breakdown 2C' 15µm 12µm 1.25 0/5 0/5 2E' 20µm 15µm 1.33 0/5 0/5 2F' 25µm 15µm 1.67 0/5 0/5 2G' 30µm 15µm 2.0 0/5 0/5 - According to the results, as for the samples 2C' and 2E' to 2G', neither local heat generation nor dielectric breakdown was found in any of the five samples throughout observation for 6 minutes. As for the samples 2E' to 2G', the temperature of the center portion of each outer wiring portion was reduced a little, but it was found that this reduction in temperature did not adversely affect thermal uniformity of the ceramic sheet.
- From the above, it was verified that local heat generation and dielectric breakdown are not likely to occur and thermal uniformity is not likely to be reduced if the thickness of the center portion of each of the pair of outer wiring portions positioned at opposite sides from each other with the wrapping-ends meeting portion therebetween is set to be not smaller than 1.25 times and not larger than 2.0 times the thickness of each inner wiring portion disposed between the pair of outer wiring portions.
- According to the present embodiment, when the thickness T3 of the
center portion 164 of eachouter wiring portion 163 is larger than the thickness T4 of eachinner wiring portion 166, electric resistance of thecenter portion 164 becomes smaller than that of theinner wiring portion 166. Therefore, at the wrapping-ends meeting portion 168 of theceramic sheet 161, where theouter wiring portions 163 are positioned, local heat generation of theheater wire 162 can be suppressed. As a result, melting of the glass component present in theceramic sheet 161 near thecenter portions 164 of theouter wiring portions 163 is suppressed, thereby inhibiting dielectric breakdown between the pair ofouter wiring portions 163, and inhibiting breakage of the ceramic heater. Therefore, reliability of the ceramic heater can be improved. - The above-described embodiments may be modified as follows.
- In the first embodiment, the line width W3 of the
connection portion 45 may be larger than the line width W1 of theouter wiring portion 46 and the line width W2 of theinner wiring portion 47. Likewise, in the second embodiment, the line width W7 of theconnection portion 67 may be larger than the line width W4 of thecenter portion 64 of theouter wiring portion 63, the line width W5 of theother portion 65 of theouter wiring portion 63, and the line width W6 of theinner wiring portion 66. - In the second embodiment, one
center portion 64 is formed in oneouter wiring portion 63. However, two or more wide portions each having the same line width as thecenter portion 64 may be formed in one outer wiring portion. When two or more wide portions are formed in one outer wiring portion, the respective wide portions may be disposed apart from each other along the direction in which the outer wiring portion extends, or may be disposed in contact with each other along the direction in which the outer wiring portion extends. - In the above embodiments, the
support member 17 of theceramic heater 11 and thesupport member 117 of theceramic heater 111 are tubular in shape. However, these support members each may have a rod shape. That is, the ceramic heaters may be used in equipment (e. g., a fan heater) other than a warm water washing toilet seat. In the above embodiments, the flange made of stainless steel is used. However, a flange made of alumina may be used, for example. - In the above embodiments, the
ceramic heater 11 and theceramic heater 111 are configured such that an AC voltage is applied across the pair ofinternal terminals 42 and across the pair ofinternal terminals 142, respectively. However, a DC voltage may be applied across the pair ofinternal terminals 42 and across the pair ofinternal terminals 142. - In the third embodiment, the conductive paste is printed dividedly in two times to make the thickness T1 of the
outer wiring portion 146 larger than the thickness T2 of theinner wiring portion 147. However, the conductive paste may be printed dividedly in three or more times to make the thickness T1 of theouter wiring portion 146 larger than the thickness T2 of theinner wiring portion 147. Likewise, in the fourth embodiment, the conductive paste is printed dividedly in two times to make the thickness T3 of thecenter portion 164 larger than the thickness T4 of theinner wiring portion 166. However, the conductive paste may be printed dividedly in three or more times to make the thickness T3 of thecenter portion 164 larger than the thickness T4 of theinner wiring portion 166. - In the third embodiment, the conductive paste is printed on the surface of the first ceramic
green sheet 151 to form the unfired electrode (first electrode 153) which forms almost the entirety of the heater wire 141 (region excluding upper-layer portions of the outer wiring portions 146). Thereafter, the conductive paste is printed on portions, of thefirst electrode 153, which will become theouter wiring portions 146, to form the unfired electrode (second electrode 154) which forms the upper-layer portions of theouter wiring portions 146. However, the conductive paste may be printed on portions, of the surface of the first ceramicgreen sheet 151, which will become theouter wiring portions 146, to form the unfired electrode which forms lower-layer portions of theouter wiring portions 146. Thereafter, the conductive paste may be printed on the unfired electrode and the surface of the first ceramicgreen sheet 151 to form the unfired electrode which forms almost the entirety of the heater wire 141 (region excluding the lower-layer portions of the outer wiring portions 146). Alternatively, the entirety of theheater wire 141 may be formed by performing printing of the conductive paste only one time by using an ink-jet apparatus or the like. - In the fourth embodiment, the conductive paste is printed on the surface of the ceramic green sheet to form the unfired electrode (first electrode) which forms almost the entirety of the heater wire 162 (region excluding upper-layer portions of the center portions 164). Thereafter, the conductive paste is printed on portions, of the first electrode, which will become the
center portions 164, to form the unfired electrode (second electrode) which forms the upper-layer portions of thecenter portions 164. However, the conductive paste may be printed on portions, of the surface of the ceramic green sheet, which will become thecenter portions 164 to form the unfired electrode which forms lower-layer portions of thecenter portions 164. Thereafter, the conductive paste may be printed on the unfired electrode and the surface of the ceramic green sheet to form the unfired electrode which forms almost the entirety of the heater wire 162 (region excluding the lower-layer portions of the center portions 164). Alternatively, the entirety of theheater wire 162 may be formed by performing printing of the conductive paste only one time by using an ink-jet apparatus or the like. - In the third embodiment, the line width of the
second electrode 154 which will become theouter wiring portions 146 is adjusted to be narrower than that of thefirst electrode 153 which also will become theouter wiring portions 146. However, the line width of thesecond electrode 154 may be equal to that of thefirst electrode 153, or may be larger than that of thefirst electrode 153. Likewise, in the fourth embodiment, the line width of the second electrode which will become thecenter portions 164 is adjusted to be narrower than the first electrode which also will become thecenter portions 164. However, the line width of the second electrode may be equal to that of the first electrode, or may be larger than that of the first electrode. - Hereinafter, the correspondence relationship of wordings will be described.
- In the above embodiments, the
ceramic heaters support members ceramic sheets - The wrapping-
ends meeting portions heater wires wiring portions connection portions - The
outer wiring portions inner wiring portions center portions
Claims (15)
- A ceramic heater (11; 111) comprising a heater body (13; 113) composed of a cylindrical or rod-shaped support member (17; 117) made of ceramic and a ceramic sheet (19; 119) which is wrapped around an outer periphery of the support member (17; 117) and includes a heater wire, whereinthe heater wire (41; 141) includes:a plurality of wiring portions (46, 47; 146, 147) extending along an axial direction of the support member (17; 117); anda connection portion (45; 145) connecting adjacent wiring portions (46, 47; 146, 147) to each other,the plurality of wiring portions (46, 47; 146, 147) include:a pair of outer wiring portions (46; 146) disposed on opposite sides from each other with a wrapping-ends meeting portion (20; 120) of the ceramic sheet therebetween; andan inner wiring portion (47; 147) disposed, in the ceramic sheet, between the pair of outer wiring portions (46; 146), andeach outer wiring portion (46; 146) has a cross-sectional area larger than that of the inner wiring portion (47; 147);characterized in that the ceramic heater further comprises an annular flange (15; 115) forming a space around the support member (17; 117) serving as reservoir (35) filled with glass (33; 133),and in that the heater body (13; 113) and the flange (15; 115) are welded and fixed via the glass (33; 133).
- The ceramic heater according to claim 1, wherein each outer wiring portion (46) has a line width, W1, larger than that of the inner wiring portion (47, 147), W2.
- The ceramic heater according to claim 2, wherein the line width of the outer wiring portion (46) is set to be larger than 1.07 times and smaller than 2.4 times the line width of the inner wiring portion (47).
- The ceramic heater according to claim 1, wherein each outer wiring portion (146, 163) has a thickness larger than that of the inner wiring portion (147, 166).
- The ceramic heater according to claim 4, wherein the thickness of the outer wiring portion is set to be larger than 1.25 times and smaller than 2.4 times the thickness of the inner wiring portion.
- The ceramic heater (11, 111) according to claim 1,
wherein a center portion (64; 164) of each outer wiring portion (63; 163) has a cross-sectional area larger than that of the inner wiring portion (66; 166). - The ceramic heater according to claim 6, wherein the center portion (64) of each outer wiring portion (63) has a line width larger than that of the inner wiring portion (66).
- The ceramic heater according to claim 7, wherein the line width of the center portion is set to be larger than 1.07 times and not larger than 2.0 times the line width of the inner wiring portion.
- The ceramic heater according to claim 6, wherein the center portion (164) of each outer wiring portion (163) has a thickness larger than that of the inner wiring portion (166).
- The ceramic heater according to claim 9, wherein the thickness of the center portion is set to be not smaller than 1.25 times and not larger than 2.0 times the thickness of the inner wiring portion.
- The ceramic heater according to any one of claims 1 to 10, wherein the support member (17; 117) and the ceramic sheet contain alumina.
- The ceramic heater according to any one of claims 1 to 11, wherein the heater wire (62; 162) contains, as a main component, at least one of tungsten and molybdenum.
- Use of the ceramic heater according to any one of claims 1 to 12 in a warm water washing toilet seat, a fan heater, an electric water heater, a 24-hour bath, a soldering iron, or a hair iron.
- The use of claim 13, wherein the applied voltage is an AC voltage.
- A method of producing the ceramic heater according to one of claims 1 to 12, the method including a printing step of printing a conductive paste on the ceramic sheet to form the heater wire; and a wrapping step of wrapping, around the support member, the ceramic sheet on which the heater wire is printed, wherein, in the printing step, the conductive paste is printed dividedly in multiple times to make the thickness of the outer wiring portion or the center portion larger than that of the inner wiring portion.
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2016051824 | 2016-03-16 | ||
JP2016051823 | 2016-03-16 | ||
PCT/JP2017/004800 WO2017159144A1 (en) | 2016-03-16 | 2017-02-09 | Ceramic heater |
Publications (3)
Publication Number | Publication Date |
---|---|
EP3432681A1 EP3432681A1 (en) | 2019-01-23 |
EP3432681A4 EP3432681A4 (en) | 2019-11-13 |
EP3432681B1 true EP3432681B1 (en) | 2024-05-29 |
Family
ID=59851113
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP17766152.7A Active EP3432681B1 (en) | 2016-03-16 | 2017-02-09 | Ceramic heater |
Country Status (5)
Country | Link |
---|---|
EP (1) | EP3432681B1 (en) |
JP (1) | JP6811177B2 (en) |
KR (1) | KR20180125993A (en) |
CN (1) | CN108781482B (en) |
WO (1) | WO2017159144A1 (en) |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP6792539B2 (en) * | 2017-10-31 | 2020-11-25 | 日本特殊陶業株式会社 | Ceramic heater for fluid heating |
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EP0701979B1 (en) * | 1994-08-18 | 1998-11-04 | Ngk Spark Plug Co., Ltd | Alumina-based sintered material for ceramic heater and ceramic heater |
DE10100125B4 (en) * | 2000-04-14 | 2015-01-08 | Kyocera Corp. | Ceramic heater |
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JPS62142189U (en) * | 1986-02-28 | 1987-09-08 | ||
JPS62167396U (en) * | 1986-04-11 | 1987-10-23 | ||
JPH0522859Y2 (en) * | 1987-11-25 | 1993-06-11 | ||
JP3038039B2 (en) * | 1991-05-01 | 2000-05-08 | 日本特殊陶業株式会社 | Ceramic heater and method of manufacturing the same |
JP2000058237A (en) * | 1998-06-05 | 2000-02-25 | Ngk Spark Plug Co Ltd | Ceramic heater and oxygen sensor using it |
JP2000266718A (en) * | 1999-03-15 | 2000-09-29 | Ngk Spark Plug Co Ltd | Oxygen sensor |
JP4181281B2 (en) * | 1999-09-08 | 2008-11-12 | 日本特殊陶業株式会社 | Oxygen sensor |
JP2001194942A (en) * | 2000-01-12 | 2001-07-19 | Ricoh Co Ltd | Image forming device |
JP2004319459A (en) * | 2003-03-27 | 2004-11-11 | Kyocera Corp | Ceramic heating resistor and heater for oxygen probe using the same |
JP4340143B2 (en) * | 2003-12-24 | 2009-10-07 | 京セラ株式会社 | Ceramic heater |
CN2731893Y (en) * | 2004-03-26 | 2005-10-05 | 京瓷株式会社 | Ceramic heater and oxygen probe using same |
JP4762539B2 (en) * | 2004-12-28 | 2011-08-31 | 日本特殊陶業株式会社 | Gas sensor |
JP2006228713A (en) * | 2005-01-20 | 2006-08-31 | Ngk Spark Plug Co Ltd | Ceramic heater, heat exchange unit, toilet seat with warm-water washing, and manufacturing method of ceramic heater |
CN2935695Y (en) * | 2006-01-17 | 2007-08-15 | 京瓷株式会社 | Ceramic heater and heating iron using the same |
DE202008003136U1 (en) * | 2008-03-05 | 2008-07-31 | Leister Process Technologies | Electric heating wedge |
CN201390777Y (en) * | 2008-08-01 | 2010-01-27 | 王青松 | Heating rod of internal heating type hot-dip galvanized device |
CN202206568U (en) * | 2011-09-07 | 2012-04-25 | 厦门格睿伟业电子科技有限公司 | Improved ceramic heating pipe |
CN202210874U (en) * | 2011-09-07 | 2012-05-02 | 厦门格睿伟业电子科技有限公司 | Porcelain heating bar capable of raising temperature fast |
JP2014163867A (en) * | 2013-02-27 | 2014-09-08 | Ngk Spark Plug Co Ltd | Gas sensor and heater element |
JP5939265B2 (en) * | 2014-02-11 | 2016-06-22 | 株式会社デンソー | Ceramic heater and gas sensor element using the same |
CN203813250U (en) * | 2014-04-15 | 2014-09-03 | 国家电网公司 | Box door of power distribution box or civil engineering station |
CN204652688U (en) * | 2015-04-08 | 2015-09-16 | 厦门格睿伟业电子科技有限公司 | A kind of ceramic heating pipe |
-
2017
- 2017-02-09 EP EP17766152.7A patent/EP3432681B1/en active Active
- 2017-02-09 WO PCT/JP2017/004800 patent/WO2017159144A1/en unknown
- 2017-02-09 KR KR1020187029270A patent/KR20180125993A/en not_active Application Discontinuation
- 2017-02-09 CN CN201780017678.2A patent/CN108781482B/en active Active
- 2017-02-09 JP JP2017535928A patent/JP6811177B2/en active Active
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EP0701979B1 (en) * | 1994-08-18 | 1998-11-04 | Ngk Spark Plug Co., Ltd | Alumina-based sintered material for ceramic heater and ceramic heater |
DE10100125B4 (en) * | 2000-04-14 | 2015-01-08 | Kyocera Corp. | Ceramic heater |
Also Published As
Publication number | Publication date |
---|---|
EP3432681A4 (en) | 2019-11-13 |
KR20180125993A (en) | 2018-11-26 |
EP3432681A1 (en) | 2019-01-23 |
JP6811177B2 (en) | 2021-01-13 |
WO2017159144A1 (en) | 2017-09-21 |
CN108781482A (en) | 2018-11-09 |
JPWO2017159144A1 (en) | 2018-03-22 |
CN108781482B (en) | 2021-08-27 |
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