JPH071191B2 - Water level sensor - Google Patents
Water level sensorInfo
- Publication number
- JPH071191B2 JPH071191B2 JP61187104A JP18710486A JPH071191B2 JP H071191 B2 JPH071191 B2 JP H071191B2 JP 61187104 A JP61187104 A JP 61187104A JP 18710486 A JP18710486 A JP 18710486A JP H071191 B2 JPH071191 B2 JP H071191B2
- Authority
- JP
- Japan
- Prior art keywords
- comparator
- voltage
- thermistor
- output
- water level
- 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 - Lifetime
Links
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims description 18
- 230000007423 decrease Effects 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 238000010438 heat treatment Methods 0.000 description 4
- 230000017525 heat dissipation Effects 0.000 description 3
- 230000004044 response Effects 0.000 description 3
- 238000001816 cooling Methods 0.000 description 2
- 238000001514 detection method Methods 0.000 description 1
- 230000010355 oscillation Effects 0.000 description 1
- 230000004043 responsiveness Effects 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
Landscapes
- Measurement Of Levels Of Liquids Or Fluent Solid Materials (AREA)
Description
【発明の詳細な説明】 産業上の利用分野 本発明は洗濯機等に用いる感温抵抗素子を利用した水位
センサーに関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water level sensor using a temperature sensitive resistance element used in a washing machine or the like.
従来の技術 従来の感温抵抗素子を用いた水位センサーは第３図に示
すように、サーミスタ１を自己発熱させておき、その時
の電圧と、抵抗分割により得られる基準電圧２とを比較
器３で比較するもので、水がサーミスタ１に触れると、
熱がうばわれてサーミスタ１の温度が下がり、抵抗値が
増すので、基準電圧２よりもサーミスタ１の電圧が高く
なり、比較器３の出力は“L"になり、ブザー４などを鳴
らすようになっている。2. Description of the Related Art In a conventional water level sensor using a temperature sensitive resistance element, as shown in FIG. 3, the thermistor 1 is caused to self-heat, and a voltage at that time and a reference voltage 2 obtained by resistance division are compared. When the water touches the thermistor 1,
As the heat is dissipated and the temperature of the thermistor 1 decreases and the resistance value increases, the voltage of the thermistor 1 becomes higher than the reference voltage 2, the output of the comparator 3 becomes "L", and the buzzer 4 etc. sounds. Has become.
発明が解決しようとする問題点 しかしながら、このような構成では、周囲温度の変化を
考えると、自己発熱状態で安定する温度は変化するの
で、その変化分を考慮して基準電圧を設定しなければな
らず、その結果、基準電圧は高くなり、比較器３の出力
が反転するまでに時間がかかり、応答性が悪いというも
のであった。DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, in such a configuration, considering the change in ambient temperature, the temperature that stabilizes in the self-heating state changes, so the reference voltage must be set in consideration of the change. As a result, the reference voltage becomes high, it takes time until the output of the comparator 3 is inverted, and the response is poor.
本発明は上記のような問題点を解決したものであり、応
答性のよい水位センサーを提供するものである。The present invention solves the above-mentioned problems and provides a water level sensor with good responsiveness.
問題点を解決するための手段 本発明は上記問題点を解決するために、感温抵抗素子を
一部に有するブリッジ回路と、このブリッジ回路の出力
を比較する比較器と、この比較器の出力に応じて前記ブ
リッジ回路に印加する電圧を、感温抵抗素子が自己発熱
する電圧と冷却する電圧とに切り換えるフィードバック
回路と、比較器の出力周期を検出する検出器とからな
り、前記感温抵抗素子が水に触れることにより比較器の
出力周期が変化したことを検出器により検知するもので
ある。Means for Solving the Problems In order to solve the above problems, the present invention provides a bridge circuit having a temperature sensitive resistance element as a part, a comparator for comparing the outputs of the bridge circuit, and an output of the comparator. The temperature-sensitive resistor includes a feedback circuit for switching the voltage applied to the bridge circuit between a voltage for self-heating and a voltage for cooling the temperature-sensitive resistance element, and a detector for detecting the output cycle of the comparator. The detector detects that the output cycle of the comparator has changed due to the contact of the element with water.
作用 本発明は上記した構成により、感温抵抗素子の自己発
熱，冷却をくり返すことにより比較器の出力はオン・オ
フをくり返す。そして、感温抵抗素子に水が触れると、
放熱状態が変化し、比較器の出力の周期が変化する。そ
の変化を検出器で検出するので応答性が良くなるもので
ある。Function The present invention has the above-described configuration, and the output of the comparator is repeatedly turned on and off by repeating self-heating and cooling of the temperature-sensitive resistance element. And when water touches the temperature sensitive resistance element,
The heat dissipation state changes, and the output cycle of the comparator changes. Since the change is detected by the detector, the response is improved.
実施例 第１図は本発明の水位センサーの一実施例を示す回路図
である。第１図において１は感温抵抗素子（以下サーミ
スタという）であり、５はサーミスタ１を一部とする抵
抗ブリッジ回路で、その出力Ａ（基準電圧）と出力Ｂ
（サーミスタ電圧）は比較器３に入力されている。６は
フィードバック回路であり、比較器３の出力が“H"のと
き、トランジスタ７はオフ、“L"のときオンである。ま
た、比較器３の出力は検出器８に接続されており、検出
器８はカウンター９の変化検出器10とから構成されてい
る。検出器８の出力はブザー４に接続されている。11は
抵抗である。Embodiment FIG. 1 is a circuit diagram showing an embodiment of the water level sensor of the present invention. In FIG. 1, reference numeral 1 is a temperature-sensitive resistance element (hereinafter referred to as a thermistor), and 5 is a resistance bridge circuit having the thermistor 1 as a part, and its output A (reference voltage) and output B
(Thermistor voltage) is input to the comparator 3. Reference numeral 6 denotes a feedback circuit. When the output of the comparator 3 is "H", the transistor 7 is off, and when it is "L" it is on. The output of the comparator 3 is connected to the detector 8, and the detector 8 is composed of a change detector 10 of a counter 9. The output of the detector 8 is connected to the buzzer 4. 11 is a resistance.
次に動作について説明する。まず、電源が供給され、サ
ーミスタ１が水に触れていない状態を考える。この時、
サーミスタ１抵抗値は大きいのでブリッジ（回路５の出
力A,Bは、Ａ（基準電圧）よりもＢ（サーミスタ電圧）
の方が高いので比較器３の出力は“L"になる。すると、
フィードバック回路６のトランジスタ７はオンになり、
ブリッジ回路５には電源電圧が印加される。なお、比較
器３の入力電圧と出力電圧の変化を第２図に示す。Next, the operation will be described. First, consider a state in which power is supplied and the thermistor 1 is not in contact with water. This time,
Since the thermistor 1 resistance is large, the bridge (the outputs A and B of the circuit 5 are B (thermistor voltage) rather than A (reference voltage)).
Is higher, the output of the comparator 3 becomes "L". Then,
The transistor 7 of the feedback circuit 6 is turned on,
A power supply voltage is applied to the bridge circuit 5. The changes in the input voltage and the output voltage of the comparator 3 are shown in FIG.
このとき、ブリッジ回路５に印加される電圧は高いの
で、サーミスタ１には大きな電流が流れ自己発熱する。
すると、サーミスタ１の抵抗値は低下して行き、サーミ
スタ電圧Ｂが下がる。そして、基準電圧４に到達すると
比較器３の出力は“H"になり、トランジスタ７はオフに
なる。すると、ブリッジ回路５には抵抗11を介して電流
が流れるので印加電圧が下がり、基準電圧A,サーミスタ
電圧Ｂともに下がる。このとき、サーミスタ１の電圧Ｂ
はアンダーシュートをおこし、その後、自己発熱はな
く、冷やされるので上昇し基準電圧Ａに到達する。する
と、再び、比較器３の出力は“L"になるので、トランジ
スタ７はオンになり、ブリッジ回路５の印加電圧は高く
なる。そして、基準電圧A,サーミスタ電圧Ｂともに上
り、その後、サーミスタ電圧Ｂはオーバーシュートする
が、再び自己発熱をおこし、サーミスタ電圧Ｂは低下す
る。この動作をくり返し、比較器３の出力は一定の周期
でもって“H",“L"をくり返す。At this time, since the voltage applied to the bridge circuit 5 is high, a large current flows through the thermistor 1 and self-heats.
Then, the resistance value of the thermistor 1 decreases, and the thermistor voltage B decreases. Then, when the reference voltage 4 is reached, the output of the comparator 3 becomes "H" and the transistor 7 is turned off. Then, since a current flows through the bridge circuit 5 through the resistor 11, the applied voltage drops, and the reference voltage A and the thermistor voltage B both drop. At this time, the voltage B of the thermistor 1
Undershoots, and thereafter, there is no self-heating and it is cooled and thus rises to reach the reference voltage A. Then, the output of the comparator 3 becomes "L" again, so that the transistor 7 is turned on and the applied voltage of the bridge circuit 5 becomes high. Then, both the reference voltage A and the thermistor voltage B rise, and then the thermistor voltage B overshoots but self-heats again and the thermistor voltage B decreases. This operation is repeated, and the output of the comparator 3 repeats "H" and "L" at a constant cycle.
検出器８では比較器３の“H"（又は“L"）の時間をカウ
ンター９で測定し、その値は変化検出器10に記憶する。In the detector 8, the “H” (or “L”) time of the comparator 3 is measured by the counter 9, and the value is stored in the change detector 10.
次に、給水を開始して、サーミスタ１に水が触れると、
サーミスタ１の熱放散状態が変化するので、比較器３の
オン，オフ周期が変化する。すると、カウンター９での
測定値が変化するので、変化検出器10では以前に記憶し
た値と比較してその変化を検出することができ、ブザー
４を駆動する。なお、第２図のＣの時点はサーミスタ１
が水に触れた状態を示す。Next, when the water supply is started and the thermistor 1 is touched by water,
Since the heat dissipation state of the thermistor 1 changes, the ON / OFF cycle of the comparator 3 changes. Then, since the measured value at the counter 9 changes, the change detector 10 can detect the change by comparing it with the previously stored value and drive the buzzer 4. The thermistor 1 is shown at the time point C in FIG.
Shows the state of touching water.
発明の効果 以上説明したように、本発明によれば、感温抵抗素子に
水が触れたことによる熱放散状態の変化を発振周期の変
化としてとらえるので、水位検知の応答速度が速い実用
的な水位センサーが提供できるものである。EFFECTS OF THE INVENTION As described above, according to the present invention, since the change in the heat dissipation state due to the contact of water with the temperature-sensitive resistance element is recognized as the change in the oscillation cycle, the response speed of water level detection is fast and practical. The water level sensor can provide.
第１図は本発明の水位センサーの一実施例を示す回路
図、第２図は比較器の入出力波形図、第３図は従来例を
示す回路図である。 １……感温抵抗素子（サーミスタ）、３……比較器、５
……ブリッジ回路、６……フィードバック回路、８……
検出器。FIG. 1 is a circuit diagram showing an embodiment of a water level sensor of the present invention, FIG. 2 is an input / output waveform diagram of a comparator, and FIG. 3 is a circuit diagram showing a conventional example. 1 ... Temperature-sensitive resistance element (thermistor), 3 ... Comparator, 5
...... Bridge circuit, 6 …… Feedback circuit, 8 ……
Detector.
───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 昭60−14125（ＪＰ，Ａ) 特開 昭59−107213（ＪＰ，Ａ) 特開 昭57−77919（ＪＰ，Ａ) ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-60-14125 (JP, A) JP-A-59-107213 (JP, A) JP-A-57-77919 (JP, A)
Claims (1)
と、このブリッジ回路の出力を比較する比較器と、この
比較器の出力に応じて前記ブリッジ回路に印加する電圧
を、感温抵抗素子が自己発熱する電圧と冷却する電圧と
に切り換えるフィードバック回路と、比較器の出力周期
を検出する検出器とからなり、前記感温抵抗素子が水に
触れることにより比較器の出力周期が変化したことを検
出器により検知する水位センサー。1. A bridge circuit having a temperature-sensitive resistance element as a part, a comparator for comparing the outputs of the bridge circuit, and a voltage applied to the bridge circuit according to the output of the comparator. The element consists of a feedback circuit that switches between a voltage that heats itself and a voltage that cools it, and a detector that detects the output cycle of the comparator, and the output cycle of the comparator changed when the temperature-sensitive resistance element touched water. A water level sensor that detects this with a detector.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP61187104A JPH071191B2 (en) | 1986-08-08 | 1986-08-08 | Water level sensor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP61187104A JPH071191B2 (en) | 1986-08-08 | 1986-08-08 | Water level sensor |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6342423A JPS6342423A (en) | 1988-02-23 |
| JPH071191B2 true JPH071191B2 (en) | 1995-01-11 |
Family
ID=16200173
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP61187104A Expired - Lifetime JPH071191B2 (en) | 1986-08-08 | 1986-08-08 | Water level sensor |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH071191B2 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH07199636A (en) * | 1993-12-28 | 1995-08-04 | Fujitsu Ltd | Toner level detector |
| CN115452094A (en) * | 2022-09-30 | 2022-12-09 | 鑫利科技(北京)有限公司 | Electronic water level sensor |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5777919A (en) * | 1980-11-04 | 1982-05-15 | Nissan Motor Co Ltd | Liquid surface detector |
| JPS59107213A (en) * | 1982-12-10 | 1984-06-21 | Mitsubishi Electric Corp | Detector for liquid level |
| JPS6014125A (en) * | 1983-07-06 | 1985-01-24 | Mitsubishi Electric Corp | Detecting circuit of liquid level |
-
1986
- 1986-08-08 JP JP61187104A patent/JPH071191B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6342423A (en) | 1988-02-23 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EXPY | Cancellation because of completion of term |