JP3124321B2 - Automatic current measurement range switching circuit - Google Patents
Automatic current measurement range switching circuitInfo
- Publication number
- JP3124321B2 JP3124321B2 JP03188905A JP18890591A JP3124321B2 JP 3124321 B2 JP3124321 B2 JP 3124321B2 JP 03188905 A JP03188905 A JP 03188905A JP 18890591 A JP18890591 A JP 18890591A JP 3124321 B2 JP3124321 B2 JP 3124321B2
- Authority
- JP
- Japan
- Prior art keywords
- voltage
- current
- current detection
- detection resistor
- connection part
- 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
Landscapes
- Measuring Instrument Details And Bridges, And Automatic Balancing Devices (AREA)
Description
【０００１】[0001]
【産業上の利用分野】この発明は、電流測定時に電流測
定時に電流検出用抵抗値を切替えるのに、外部からの制
御信号を必要とせずに、電流検出用抵抗を流れる電流量
によって自動的に行えるようにした電流測定回路の自動
レンジ切替え装置に関するものである。BACKGROUND OF THE INVENTION This invention is to switch the current detection resistor value at the current measured at the current measurement, without requiring an external control signal automatically by the amount of current flowing through the current detection resistor The present invention relates to an automatic range switching device for a current measurement circuit that can be used.
【０００２】[0002]
【従来の技術】従来のレンジ切換方法として、リレーを
各電流検出抵抗に並列に接続し、必要とするレンジの検
出抵抗以外のリレーを外部からのリレー制御信号でＯＮ
させ、電流をリレーに流すことにより、検出抵抗による
電圧降下をおさえ、電圧供給用の出力バッファの電圧が
飽和状態になるのを防いでいた。2. Description of the Related Art As a conventional range switching method, a relay is connected in parallel to each current detecting resistor, and relays other than the necessary range of the detecting resistor are turned on by an external relay control signal.
Then, by flowing a current through the relay, the voltage drop due to the detection resistor is suppressed, and the voltage of the output buffer for supplying the voltage is prevented from becoming saturated.
【０００３】[0003]
【発明が解決しようとする課題】しかし、従来の技術は
リレーを使用しているため、電流検出回路のプリント基
板に占める実装面積が大きく、またリレーをロジック信
号で制御するため、制御回路が必要となり、電流検出回
路全体が大きくなってしまい装置の小型化には適してい
ないという欠点があった。この発明は、従来のこのよう
な欠点を解決するためにリレーを使用せずにレンジの切
換えを行うことを目的としたものである。However, in the prior art, since a relay is used, the mounting area of the current detection circuit on the printed circuit board is large, and a control circuit is required to control the relay by a logic signal. Therefore, there is a disadvantage that the entire current detection circuit becomes large and is not suitable for miniaturization of the device. An object of the present invention is to perform range switching without using a relay in order to solve such a conventional disadvantage.
【０００４】[0004]
【課題を解決するための手段】上記課題を解決するため
に、この発明はレンジ切換え時のリレーのＯＮ／ＯＦＦ
をダイオードのブリッジ構造にし、ダイオードの順方向
電流によるリークをなくすため、ダイオードブリッジ構
造に定電流源を接続し、電流検出回路のゲインによるオ
フセット誤差を少なくするため、電流検出抵抗の最大検
出レンジ電圧を０．４Ｖにしたものである。SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a method of turning on / off a relay at the time of range switching.
Is connected to a diode bridge structure, a constant current source is connected to the diode bridge structure to eliminate leakage due to the forward current of the diode, and the maximum detection range voltage of the current detection resistor is set to reduce the offset error due to the gain of the current detection circuit. Is set to 0.4V.
【０００５】[0005]
【実施例】図１において、電圧増幅回路１に電圧を設定
することにより負荷１４に電圧が印加される。それによ
って流れる電流が電流検出抵抗６と７に流れることによ
って生じる電圧降下を電流検出回路２によって電流測定
する。以上の構成において、大きいレンジを使用する場
合、アナログスイッチ１２をＯＦＦ、アナログスイッチ
１３をＯＮにし検出抵抗７に流れる電流によって生じる
電圧降下電圧（接続点１６と１７間）の電圧を検出し電
流測定を行う。この時の検出抵抗７の値は、レンジの最
大検出電圧が０．４Ｖになるように決める。ダイオード
に流れる電流は負荷に正電圧が印加された時、ダイオー
ド１０、１１がＯＮ、ダイオード８、９がＯＦＦにな
り、ダイオード１０と１１に電流が流れ、負電圧が印加
された時はダイオード８と９に電流が流れる。電流バッ
ファ３の出力電圧２０は±ＶIN（印加電圧）±０．４Ｖ
±２ＶF （ＶF ：ダイオード順方向電圧）になり、飽和
電圧になるのを防ぐことができる。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, a voltage is applied to a load 14 by setting a voltage in a voltage amplifier circuit 1. The voltage drop caused by the current flowing through the current detection resistors 6 and 7 is measured by the current detection circuit 2. In the above configuration, when a large range is used, the analog switch 12 is turned off, the analog switch 13 is turned on, and the voltage of the voltage drop voltage (between the connection points 16 and 17) caused by the current flowing through the detection resistor 7 is detected to measure the current. I do. At this time, the value of the detection resistor 7 is determined so that the maximum detection voltage of the range becomes 0.4 V. When a positive voltage is applied to the load, the diodes 10 and 11 are turned on, and the diodes 8 and 9 are turned off. When a negative voltage is applied, the current flows through the diodes 10 and 11. And 9 flow current. The output voltage 20 of the current buffer 3 is ± VIN (applied voltage) ± 0.4V
± 2V F (V F : diode forward voltage) to prevent saturation voltage.
【０００６】小さい電流レンジを使用する場合、アナロ
グスイッチ１２をＯＮ、アナログスイッチ１３をＯＦＦ
にし、電流検出抵抗６、７に流れる電流によって生じる
電圧降下電圧（１５、１７間）の電圧を検出し電流の測
定を行う。この時の検出抵抗の値はレンジの最大検出電
圧（接続点１５と１７間）が０．４Ｖになるように決め
る。よって検出抵抗７の値は両レンジを満足する値でな
くてはならない。ダイオードの状態は、ここではＲ1 》
Ｒ2 （Ｒ1 とＲ2 は抵抗６と７の抵抗値）としているの
で接続点１５と１６間の電圧をレンジの最大検出時電圧
値約０．４Ｖと考え、検出抵抗７による電圧降下を無視
すると、負荷に正電圧ＶINが印加された時、接続点１６
の電圧は約ＶINになり、接続点１５の電圧はレンジの最
大検出時でＶIN＋０．４Ｖになる。この状態において、
接続点１９の電圧はＶIN＋０．４Ｖ＋ＶF （ダイオード
順方向電圧約０．６Ｖ）となり、ダイオード８には逆電
圧がかかり電流は流れない。また接続点１８の電圧は、
ＶIN＋０．４Ｖ−ＶF となり、ダイオード１１にも逆電
圧がかかることになり電流は流れない。負荷に負電圧が
印加された状態でもダイオード８と１１には逆電圧がか
かることになる。よって電流検出抵抗に流れる電流は、
負荷に流れる電流のみになり電流測定回路として動作す
る。なお、本説明では２レンジのみであったが、本発明
は多レンジに対しても同様の考えで適用することができ
る。When a small current range is used, the analog switch 12 is turned on and the analog switch 13 is turned off.
Then, the voltage of the voltage drop voltage (between 15 and 17) generated by the current flowing through the current detection resistors 6 and 7 is detected, and the current is measured. The value of the detection resistor at this time is determined so that the maximum detection voltage of the range (between the connection points 15 and 17) becomes 0.4V. Therefore, the value of the detection resistor 7 must be a value that satisfies both ranges. The state of the diode here is R 1 >>
Since R 2 (R 1 and R 2 are the resistances of the resistors 6 and 7), the voltage between the connection points 15 and 16 is considered to be about 0.4 V at the time of the maximum detection of the range. If ignored, when the positive voltage VIN is applied to the load, the connection point 16
Is about VIN, and the voltage at the connection point 15 becomes V IN +0.4 V at the time of maximum detection of the range. In this state,
The voltage at the connection point 19 becomes V IN +0.4 V + V F (diode forward voltage: about 0.6 V), and a reverse voltage is applied to the diode 8 so that no current flows. The voltage at the connection point 18 is
V IN + 0.4V - V F, and the current will also be a reverse voltage across the diode 11 does not flow. Even when a negative voltage is applied to the load, a reverse voltage is applied to the diodes 8 and 11. Therefore, the current flowing through the current detection resistor is
Only the current flowing to the load becomes available, and it operates as a current measuring circuit. In this description, only two ranges are used. However, the present invention can be applied to multiple ranges with the same concept.
【０００７】[0007]
【発明の効果】本発明は、リレーによるレンジ切換えの
代わりにダイオードを使用し、ダイオード使用時におけ
る検出電圧を高くすることにより部品実装面積を減らす
ようにしたもので、装置の小型化をするために有効な回
路である。According to the present invention, a diode is used in place of range switching by a relay, and the detection voltage when the diode is used is increased to reduce the component mounting area. This is an effective circuit.
【図１】本発明の電流検出回路図である。FIG. 1 is a diagram of a current detection circuit according to the present invention.
１ 電圧増幅回路 ２ 電流検出回路 ３ 電流バッファ ４、５ 定電流ダイオード ６、７ 電流検出抵抗 ８〜１１ ダイオード １２、１３ アナログスイッチ １４ 負荷 １５〜２０ 各点の電圧ポイント DESCRIPTION OF SYMBOLS 1 Voltage amplifier circuit 2 Current detection circuit 3 Current buffer 4, 5 Constant current diode 6, 7 Current detection resistor 8-11 Diode 12, 13 Analog switch 14 Load 15-20 Voltage point of each point
Claims (1)
ードを順方向に環状に配置したブリッジ構造と、前記ブ
リッジ構造の第１と第２の２つのダイオードの接続部で
ある第１の接続部と他の第３と第４の２つのダイオード
の接続部である第２の接続部との間に設けられた第１の
電流検出抵抗と、前記第２と第３のダイオードの接続部
である第３の接続部及び前記第１と第４のダイオードの
接続部である第４の接続部にそれぞれ接続された２つの
定電流源と、一端が前記第１の接続部に接続され、前記
第１の電流検出抵抗より抵抗値の低い第２の電流検出抵
抗と、前記第２の電流検出抵抗の他端に設けられた負荷
と、一端の入力は前記負荷と前記第２の電流検出抵抗の
間に接続され、他端の入力は平列にそれぞれアナログス
イッチを介して第１の接続部及び第２の接続部に接続さ
れた電流検出回路とからなることを特長とする電流測定
レンジ自動切換装置。1. A bridge structure in which first, second, third, and fourth four diodes are annularly arranged in a forward direction, and a bridge, which is a connection portion between the first and second two diodes of the bridge structure. A first current detection resistor provided between the first connection portion and a second connection portion which is a connection portion between the other third and fourth two diodes; Two constant current sources respectively connected to a third connection part which is a connection part and a fourth connection part which is a connection part of the first and fourth diodes, and one end is connected to the first connection part. And said
A second current detection resistor having a lower resistance value than the first current detection resistor, a load provided at the other end of the second current detection resistor, and an input at one end is the load and the second current detection resistor Characterized in that the input at the other end comprises a current detection circuit connected in parallel to the first connection part and the second connection part via analog switches, respectively. Switching device.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP03188905A JP3124321B2 (en) | 1991-07-29 | 1991-07-29 | Automatic current measurement range switching circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP03188905A JP3124321B2 (en) | 1991-07-29 | 1991-07-29 | Automatic current measurement range switching circuit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0534381A JPH0534381A (en) | 1993-02-09 |
| JP3124321B2 true JP3124321B2 (en) | 2001-01-15 |
Family
ID=16231939
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP03188905A Expired - Lifetime JP3124321B2 (en) | 1991-07-29 | 1991-07-29 | Automatic current measurement range switching circuit |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3124321B2 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100331438B1 (en) * | 1995-08-26 | 2002-08-21 | 삼성전자 주식회사 | Resolution improving circuit of analog-to-digital converter for current sensor |
| CN104655920B (en) * | 2015-02-03 | 2017-12-01 | 浙江师范大学 | A kind of micro-current detection means for unimolecule conductance measurement system |
-
1991
- 1991-07-29 JP JP03188905A patent/JP3124321B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0534381A (en) | 1993-02-09 |
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