JPS6317206B2 - - Google Patents

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Publication number
JPS6317206B2
JPS6317206B2 JP56060280A JP6028081A JPS6317206B2 JP S6317206 B2 JPS6317206 B2 JP S6317206B2 JP 56060280 A JP56060280 A JP 56060280A JP 6028081 A JP6028081 A JP 6028081A JP S6317206 B2 JPS6317206 B2 JP S6317206B2
Authority
JP
Japan
Prior art keywords
mol
humidity
sintered body
resistance value
oxide
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
JP56060280A
Other languages
Japanese (ja)
Other versions
JPS57173904A (en
Inventor
Juji Yokomizo
Keiji Juki
Naoe Watabe
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Marcon Electronics Co Ltd
Original Assignee
Marcon Electronics Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Marcon Electronics Co Ltd filed Critical Marcon Electronics Co Ltd
Priority to JP56060280A priority Critical patent/JPS57173904A/en
Publication of JPS57173904A publication Critical patent/JPS57173904A/en
Publication of JPS6317206B2 publication Critical patent/JPS6317206B2/ja
Granted legal-status Critical Current

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  • Investigating Or Analyzing Materials By The Use Of Fluid Adsorption Or Reactions (AREA)
  • Compositions Of Oxide Ceramics (AREA)
  • Non-Adjustable Resistors (AREA)

Description

【発明の詳細な説明】[Detailed description of the invention]

本発明は、金属酸化物からなり湿度の変化を電
気抵抗の変化として検出する感湿素子に関する。 一般に金属酸化物は吸水性に優れているため、
この性質を利用して感湿素子として利用しうるこ
とが知られている。すなわち、Fe2O3、Fe3O4
Al2O3、Cr2O3などの金属酸化物の微粉末を無機
質絶縁基板の表面に塗布して感湿膜を形成し、こ
の膜の電気抵抗の湿度に対する変化を利用したも
のである。この種の感湿素子は、物理的、化学
的、熱的に安定であるが、概して固有抵抗が高い
ため吸脱湿現象によつて多少の抵抗変化があつて
もこれを電気的に高精度に検出することは難し
い。また、スピネル構造酸化物の半導体性を利用
したものは抵抗値が比較的低く、相対湿度0〜
100%の全領域の湿度を検出することができる。
しかしながら、室温で放置すると抵抗値が増加し
再現性が得にくい。この欠点をなくすために加熱
することが考えられているが、加熱によつて再現
性は得られても繰返し加熱による電極材の経時特
性に難点があり、信頼性に欠け、かつ構造が複雑
になる欠点があつた。 本発明は上記のような事情に鑑みてなされたも
ので、金属酸化物の酸化亜鉛(ZnO)、酸化マグ
ネシウム(MgO)、酸化クロム(Cr2O3)、酸化バ
ナジウム(V2O5)および酸化リチウム(Li2O)
に換算してそれぞれ49.95〜29.95モル%、20〜
0.05モル%、29.95〜50モル%、0.05〜10モル%お
よび0.05〜10モル%の組成を有する焼結体で構成
することによつて、抵抗値が比較的低く室温放置
で加熱しなくとも抵抗値は安定で、経時特性も優
れており、しかも湿度ヒステリシスの小さい85℃
の高温に放置しても安定な感湿素子の得られるこ
とがわかつた。したがつて、本発明は焼結体で安
定性が良好で信頼性の高い感湿素子を提供せんと
するものである。 以下、本発明を詳細に説明する。 実施例 1 本発明は、金属酸化物のZnO、MgO、Cr2O3
V2O5、Li2Oに換算して、それぞれ49.95〜29.95モ
ル%、20〜0.05モル%、29.95〜50モル%、0.05〜
10モル%、0.05〜10モル%の組成を有する焼結体
からなることを特徴とするものであつて、例えば
第1図に示すように構成し使用される。図中1は
本発明に係る素子の感湿部で金属酸化物である
ZnO−MgO−Cr2O3−V2O5−Li2Oを焼結した焼
結体である。2,3は電極で焼結体1とよく密着
して接触抵抗が小さく耐湿性のよい電極材料、例
えば金ペーストまたは銀ペーストで形成される。
4,5は電極2,3に取着した端子である。 このような本発明の感湿素子は、例えば次のよ
うな方法によつて製造できる。すなわち、金属酸
化物であるZnO40モル%、MgO7.5モル%、
Cr2O342.5モル%、V2O55モル%、Li2O5モル%を
秤取し、これをボールミルでよく混合する。次い
でこれらの混合物を850℃の温度で2時間予備焼
成して、これをさらにボールミルで粉砕した。し
かるのち、この粉体に粘結剤としてポリビニルア
ルコールを添加混合し、1ton/cm2の圧力で厚さ1
mm×直径10mmの円板に成形する。次いでこの成形
体を1300℃の温度で空気雰囲気中で1時間焼結す
る。この焼結体1は、この焼結によつて前記金属
酸化物が互いに反応してできていると予想される
ZnxMg1-xCr2O4などから構成されているものと
思われる。この焼結体1の両面を研摩して厚さ
0.3mmとし、この両面に第1図のように金ペース
トを塗布焼付けして電極2,3を形成し、該電極
2,3にそれぞれ端子4,5を接続する。 このようにして得られた本発明の実施例Aによ
る感湿素子と従来の参考例Bによる感湿素子との
湿度−抵抗特性、経時特性およびヒステリシスの
比較を第2図〜第5図に示す。参考例Bはスピネ
ル構造酸化物からなるMgCr2O4系感湿素子であ
るが、いずれも実施例Aの方が優れた結果を示し
ている。すなわち第2図の湿度−抵抗特性におい
て、参考例Bは抵抗値が高く変化桁も3桁程度で
大きいという欠点がある。これに対して実施例A
は抵抗値が低く変化桁も2桁程度で、参考例Bと
比較して計測回路とのマツチングに大きな利点を
もつている。第3図〜第5図は、実施例Aの感湿
素子と参考例Bの感湿素子との経時特性の比較を
示したもので、温度35℃、温度90%RHの雰囲気
中で1000時間経過したのち各素子を温度25℃、湿
度50%RH、70%RH、90%RHの抵抗値を初期値
と比較して湿度に換算し、湿度変化率として示し
たものである。第3図が湿度50%RHの場合、第
4図が湿度70%RHの場合、第5図が湿度90%
RHの場合の変化率である。これによれば実施例
Aはほとんど変化せず安定であるが、参考例Bは
変化率が大きくマイナス方向に変化する。第6図
〜第8図は実施例Aの感湿素子の高温85℃におけ
る経時特性を示したもので、1000時間経過したの
ち温度25℃、湿度50%RH、70%RH、90%RHの
抵抗値を初期値と比較して湿度に換算し湿度変化
率として示したものである。 これらから実施例Aの感湿素子は高温雰囲気中
で安定であり、高温でも十分使用できることを示
している。 実施例 2 次に本発明におけるZnO、MgO、Cr2O3
V2O5およびLi2Oの組成比の限定理由について第
9図〜第13図によつて説明する。第9図は焼結
体を金属酸化物にそれぞれ換算したとき、焼結体
に占めるZnOの組成比と焼結体の平均粒径との関
係を示したもので、この実施例の組成は表1のと
おりであり、素子の作製は実施例1と同様の条件
で行つた。
The present invention relates to a humidity sensing element made of metal oxide and detecting changes in humidity as changes in electrical resistance. Metal oxides generally have excellent water absorption, so
It is known that this property can be used as a moisture-sensitive element. That is, Fe 2 O 3 , Fe 3 O 4 ,
A moisture-sensitive film is formed by applying fine powder of a metal oxide such as Al 2 O 3 or Cr 2 O 3 to the surface of an inorganic insulating substrate, and the change in electrical resistance of this film with respect to humidity is utilized. This type of moisture sensing element is physically, chemically, and thermally stable, but because it generally has a high specific resistance, even if there is a slight change in resistance due to moisture absorption and desorption, this can be electrically processed with high accuracy. difficult to detect. In addition, those that utilize the semiconducting properties of spinel structure oxides have a relatively low resistance value, and the relative humidity ranges from 0 to
Can detect humidity of 100% entire area.
However, if left at room temperature, the resistance value increases and reproducibility is difficult to obtain. Heating has been considered to eliminate this drawback, but even though heating can improve reproducibility, repeated heating has problems with the aging characteristics of the electrode material, resulting in a lack of reliability and a complicated structure. There was a drawback. The present invention has been made in view of the above circumstances, and uses metal oxides such as zinc oxide (ZnO), magnesium oxide (MgO), chromium oxide (Cr 2 O 3 ), vanadium oxide (V 2 O 5 ) and Lithium oxide ( Li2O )
49.95~29.95 mol%, 20~
By being composed of sintered bodies having compositions of 0.05 mol%, 29.95 to 50 mol%, 0.05 to 10 mol%, and 0.05 to 10 mol%, the resistance value is relatively low and the resistance can be maintained even when left at room temperature without heating. Stable values, excellent aging characteristics, and low humidity hysteresis at 85℃
It has been found that a stable moisture-sensitive element can be obtained even when left at high temperatures. Therefore, it is an object of the present invention to provide a moisture-sensitive element which is a sintered body, has good stability, and is highly reliable. The present invention will be explained in detail below. Example 1 The present invention uses metal oxides ZnO, MgO, Cr 2 O 3 ,
49.95 to 29.95 mol%, 20 to 0.05 mol%, 29.95 to 50 mol%, and 0.05 to 0.05 mol%, respectively, in terms of V 2 O 5 and Li 2 O.
It is characterized by being made of a sintered body having a composition of 10 mol % and 0.05 to 10 mol %, and is used, for example, in the structure shown in FIG. In the figure, 1 is a metal oxide moisture sensitive part of an element according to the present invention.
It is a sintered body made by sintering ZnO−MgO−Cr 2 O 3 −V 2 O 5 −Li 2 O. Reference numerals 2 and 3 denote electrodes which are made of an electrode material that is in close contact with the sintered body 1 and has low contact resistance and good moisture resistance, such as gold paste or silver paste.
4 and 5 are terminals attached to the electrodes 2 and 3. Such a moisture-sensitive element of the present invention can be manufactured, for example, by the following method. That is, metal oxides ZnO 40 mol%, MgO 7.5 mol%,
42.5 mol% of Cr 2 O 3 , 5 mol % of V 2 O 5 , and 5 mol % of Li 2 O are weighed out and thoroughly mixed in a ball mill. These mixtures were then precalcined at a temperature of 850° C. for 2 hours and further ground in a ball mill. After that, polyvinyl alcohol was added and mixed as a binder to this powder, and the powder was molded to a thickness of 1 ton/ cm2 under a pressure of 1 ton/cm2.
Form into a disk of mm x 10 mm diameter. This compact is then sintered at a temperature of 1300° C. in an air atmosphere for 1 hour. This sintered body 1 is expected to be formed by the metal oxides reacting with each other due to this sintering.
It seems to be composed of Zn x Mg 1-x Cr 2 O 4 etc. Both sides of this sintered body 1 are polished to give a thickness
0.3 mm, gold paste is applied and baked on both sides as shown in FIG. 1 to form electrodes 2 and 3, and terminals 4 and 5 are connected to the electrodes 2 and 3, respectively. Comparisons of humidity-resistance characteristics, aging characteristics, and hysteresis between the humidity-sensitive element according to Example A of the present invention and the conventional humidity-sensitive element according to Reference Example B thus obtained are shown in FIGS. 2 to 5. . Reference Example B is an MgCr 2 O 4 moisture sensitive element made of a spinel structure oxide, but Example A shows better results in both cases. That is, in the humidity-resistance characteristics shown in FIG. 2, Reference Example B has a drawback in that the resistance value is high and the change in resistance is large, on the order of three orders of magnitude. In contrast, Example A
has a low resistance value and a change in the order of magnitude of about two orders of magnitude, and has a great advantage in matching with the measurement circuit compared to Reference Example B. Figures 3 to 5 show a comparison of the aging characteristics of the humidity sensing element of Example A and the humidity sensing element of Reference Example B, and are shown for 1000 hours in an atmosphere at a temperature of 35°C and a temperature of 90% RH. After the time has elapsed, the resistance values of each element at a temperature of 25°C and a humidity of 50% RH, 70% RH, and 90% RH are compared with the initial values, converted to humidity, and shown as a humidity change rate. If the humidity is 50%RH in Figure 3, if the humidity is 70%RH in Figure 4, then the humidity is 90% in Figure 5.
This is the rate of change in the case of RH. According to this, Example A is stable with almost no change, but Reference Example B has a large rate of change and changes in a negative direction. Figures 6 to 8 show the aging characteristics of the humidity sensing element of Example A at a high temperature of 85°C. The resistance value is compared with the initial value, converted into humidity, and shown as a humidity change rate. These results show that the humidity sensitive element of Example A is stable in a high temperature atmosphere and can be used satisfactorily even at high temperatures. Example 2 Next, ZnO, MgO, Cr 2 O 3 in the present invention,
The reasons for limiting the composition ratios of V 2 O 5 and Li 2 O will be explained with reference to FIGS. 9 to 13. Figure 9 shows the relationship between the composition ratio of ZnO in the sintered body and the average grain size of the sintered body when the sintered body is converted into metal oxide. 1, and the device was manufactured under the same conditions as in Example 1.

【表】 この結果からZnO29.95モル%未満の場合およ
び49.95モル%を超える場合には、焼結体の平均
粒径が2μmを超え気孔率が小さくなり、感湿素
子として望ましくない。 第10図は第9図の場合と同じく焼結体を金属
酸化物に換算したとき焼結体に占めるMgOの組
成比と応答速度との関係を示したもので、表2の
組成を用い、素子の作製は実施例1と同様の条件
で行つた。
[Table] From this result, when ZnO2 is less than 9.95 mol% and when it exceeds 49.95 mol%, the average particle size of the sintered body exceeds 2 μm and the porosity becomes small, which is not desirable as a moisture-sensitive element. Figure 10 shows the relationship between the composition ratio of MgO in the sintered body and the response speed when the sintered body is converted into metal oxide, as in the case of Figure 9. Using the composition in Table 2, The device was manufactured under the same conditions as in Example 1.

【表】 この結果からMgOが0.05モル%未満の場合お
よび20モル%を超える場合には、応答速度が急激
に遅くなる傾向を示し望ましくない。 第11図は第9図の場合と同じく焼結体を金属
酸化物に換算したとき焼結体に占めるCr2O3の組
成比と焼結体の平均粒径との関係を示したもの
で、表3の組成を用い、素子の作製は実施例1と
同様の条件で行つた。
[Table] The results show that when MgO is less than 0.05 mol% and when it exceeds 20 mol%, the response speed tends to decrease rapidly, which is not desirable. Figure 11 shows the relationship between the composition ratio of Cr 2 O 3 in the sintered body and the average grain size of the sintered body when the sintered body is converted into metal oxide, as in the case of Figure 9. Using the composition shown in Table 3, the device was manufactured under the same conditions as in Example 1.

【表】 この結果からCr2O329.95モル%未満の場合およ
び50モル%を超える場合には、前記ZnOの場合と
同様に焼結体の平均粒径が2μmを超え気孔率が
小さくなり感湿素子として不適である。 また第12図は焼結体を金属酸化物に換算した
とき焼結体に占めるV2O5の組成比と焼結体の抵
抗値との関係を示したもので、湿度60%RHの場
合のV2O5の組成比に対応する抵抗値の変化であ
るが、表4に示すような組成を用い、素子の作製
は実施例1と同様の条件で行つたものである。
[Table] From this result, when Cr 2 O 3 is less than 29.95 mol% and exceeds 50 mol%, the average grain size of the sintered body exceeds 2 μm and the porosity becomes small, as in the case of ZnO. Not suitable as a wet element. In addition, Figure 12 shows the relationship between the composition ratio of V 2 O 5 in the sintered body and the resistance value of the sintered body when the sintered body is converted to metal oxide, and when the humidity is 60% RH. The change in resistance value corresponding to the composition ratio of V 2 O 5 is shown in Table 4. The device was manufactured under the same conditions as in Example 1 using the composition shown in Table 4.

【表】 この結果V2O50.05〜10モル%の範囲での抵抗
値は105Ωの領域に入つているが、0.05モル%未
満の場合および10モル%を超える場合には抵抗値
が増大する傾向にあつて計測回路とのマツチング
が悪く感湿素子として不適である。 さらに第13図は焼結体を金属酸化物に換算し
たとき焼結体に占めるLi2Oの組成比に対応する
抵抗値の変化を示したものであるが、表5に示す
ような組成を用い、素子の作製は実施例1と同様
の条件で行つた。
[Table] As a result, the resistance value in the range of V 2 O 5 0.05 to 10 mol% is in the 10 5 Ω region, but the resistance value decreases when it is less than 0.05 mol% and when it exceeds 10 mol%. This tends to increase, and the matching with the measurement circuit is poor, making it unsuitable as a humidity sensing element. Furthermore, Figure 13 shows the change in resistance value corresponding to the composition ratio of Li 2 O in the sintered body when the sintered body is converted into metal oxide. The device was manufactured under the same conditions as in Example 1.

【表】 この結果Li2O0.05〜10モル%の範囲での抵抗値
は105Ωの領域に入つているが、0.05モル%未満
の場合は抵抗値が増大する傾向にあり、10モル%
を超える場合には抵抗値は低下するが経時特性が
悪く良好な感湿素子が得られない。 これらから明らかなように金属酸化物のZnO、
MgO、Cr2O3、V2O5、Li2Oに換算して、それぞ
れ49.95〜29.95モル%、20〜0.05モル%、29.95〜
50モル%、0.05〜10モル%、0.05〜10モル%が最
適組成範囲であることがわかる。 なお上記実施例では成形体を焼結温度1300℃、
焼結時間1hで焼結した場合について述べたが、
焼結温度1200〜1400℃、焼結時間1〜5hの範囲
で焼結した素子でも同様の効果を得ることができ
たことから、実施例と同様ZnxMg1-xCr2O4など
ができていることが予想される。 以上詳述したように本発明によれば、金属酸化
物に換算してZnO49.95〜29.95モル%、MgO20〜
0.05モル%、Cr2O329.95〜50モル%、V2O50.05〜
10モル%およびLi2O0.05〜10モル%の組成を有す
る焼結体からなることを特徴とし、抵抗値が低く
室温放置で加熱しなくとも抵抗値は安定で経時特
性も優れており、しかも湿度ヒステリシスの小さ
い、そして高温領域での使用においても信頼性の
高い感湿素子を得ることができる。
[Table] As a result, the resistance value in the range of 0.05 to 10 mol% Li 2 O is in the 10 5 Ω region, but when it is less than 0.05 mol%, the resistance value tends to increase; %
If it exceeds this value, the resistance value decreases, but the aging characteristics are poor and a good moisture-sensitive element cannot be obtained. As is clear from these, the metal oxide ZnO,
In terms of MgO, Cr2O3 , V2O5 , Li2O , 49.95 to 29.95 mol%, 20 to 0.05 mol%, and 29.95 to 29.95 mol%, respectively .
It can be seen that the optimum composition ranges are 50 mol%, 0.05 to 10 mol%, and 0.05 to 10 mol%. In the above example, the molded body was sintered at a temperature of 1300°C.
We have described the case of sintering with a sintering time of 1 hour,
Similar effects could be obtained with elements sintered at a sintering temperature of 1200 to 1400°C and a sintering time of 1 to 5 hours, so Zn x Mg 1-x Cr 2 O 4 etc. It is expected that it will be completed. As detailed above, according to the present invention, in terms of metal oxide, ZnO49.95 to 29.95 mol%, MgO20 to
0.05 mol% , Cr2O3 29.95~50 mol%, V2O5 0.05 ~
It is characterized by being composed of a sintered body with a composition of 10 mol% Li 2 O and 0.05 to 10 mol% Li 2 O, and has a low resistance value, stable resistance value even without heating when left at room temperature, and excellent aging characteristics. Moreover, it is possible to obtain a humidity sensing element that has small humidity hysteresis and is highly reliable even when used in a high temperature range.

【図面の簡単な説明】[Brief explanation of the drawing]

第1図は本発明に係る感湿素子の一実施例を示
す断面図、第2図は湿度−抵抗特性を示す曲線
図、第3図〜第8図はそれぞれ経時特性を示す曲
線図、第9図は焼結体を金属酸化物に換算したと
きの焼結体に占めるZnOの組成比と平均粒径との
関係を示す曲線図、第10図は同じくMgOの組
成比と応答速度との関係を示す曲線図、第11図
は同じくCr2O3の組成比と平均粒径との関係を示
す曲線図、第12図は同じくV2O5の組成比と抵
抗値との関係を示す曲線図、第13図は同じく
Li2Oの組成比と抵抗値との関係を示す曲線図で
ある。 1……焼結体、2,3……電極、4,5……端
子。
FIG. 1 is a cross-sectional view showing one embodiment of the humidity sensing element according to the present invention, FIG. 2 is a curve diagram showing humidity-resistance characteristics, and FIGS. 3 to 8 are curve diagrams showing temporal characteristics, respectively. Figure 9 is a curve diagram showing the relationship between the composition ratio of ZnO in the sintered body and the average grain size when the sintered body is converted into metal oxide, and Figure 10 is a curve diagram showing the relationship between the composition ratio of MgO and the response speed. A curve diagram showing the relationship, Figure 11 is a curve diagram showing the relationship between the composition ratio of Cr 2 O 3 and the average particle size, and Figure 12 is a curve diagram showing the relationship between the composition ratio of V 2 O 5 and the resistance value. The curve diagram and Figure 13 are the same.
FIG. 3 is a curve diagram showing the relationship between the composition ratio of Li 2 O and the resistance value. 1... Sintered body, 2, 3... Electrode, 4, 5... Terminal.

Claims (1)

【特許請求の範囲】[Claims] 1 金属酸化物の酸化亜鉛、酸化マグネシウム、
酸化クロム、酸化バナジウム、酸化リチウムに換
算して、それぞれ49.95〜29.95モル%、20〜0.05
モル%、29.95〜50モル%、0.05〜10モル%、0.05
〜10モル%の組成を有する焼結体からなることを
特徴とする感湿素子。
1 Metal oxides zinc oxide, magnesium oxide,
49.95 to 29.95 mol% and 20 to 0.05 in terms of chromium oxide, vanadium oxide, and lithium oxide, respectively
Mol%, 29.95-50 Mol%, 0.05-10 Mol%, 0.05
A moisture-sensitive element comprising a sintered body having a composition of ~10 mol%.
JP56060280A 1981-04-20 1981-04-20 Moisture sensitive element Granted JPS57173904A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP56060280A JPS57173904A (en) 1981-04-20 1981-04-20 Moisture sensitive element

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP56060280A JPS57173904A (en) 1981-04-20 1981-04-20 Moisture sensitive element

Publications (2)

Publication Number Publication Date
JPS57173904A JPS57173904A (en) 1982-10-26
JPS6317206B2 true JPS6317206B2 (en) 1988-04-13

Family

ID=13137571

Family Applications (1)

Application Number Title Priority Date Filing Date
JP56060280A Granted JPS57173904A (en) 1981-04-20 1981-04-20 Moisture sensitive element

Country Status (1)

Country Link
JP (1) JPS57173904A (en)

Also Published As

Publication number Publication date
JPS57173904A (en) 1982-10-26

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