JPS6329259Y2 - - Google Patents
Info
- Publication number
- JPS6329259Y2 JPS6329259Y2 JP7448679U JP7448679U JPS6329259Y2 JP S6329259 Y2 JPS6329259 Y2 JP S6329259Y2 JP 7448679 U JP7448679 U JP 7448679U JP 7448679 U JP7448679 U JP 7448679U JP S6329259 Y2 JPS6329259 Y2 JP S6329259Y2
- Authority
- JP
- Japan
- Prior art keywords
- circuit
- constant current
- resistance
- diode
- measured
- 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
Links
- 230000002159 abnormal effect Effects 0.000 claims description 17
- 238000005259 measurement Methods 0.000 claims description 17
- 230000005856 abnormality Effects 0.000 description 7
- 238000010586 diagram Methods 0.000 description 4
- 239000003990 capacitor Substances 0.000 description 2
- 239000004973 liquid crystal related substance Substances 0.000 description 2
- 230000001681 protective effect Effects 0.000 description 2
- 230000000903 blocking effect Effects 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000009499 grossing Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000000034 method Methods 0.000 description 1
Landscapes
- Measurement Of Resistance Or Impedance (AREA)
Description
【考案の詳細な説明】
本考案は回路計など多くの測定機能を有する抵
抗測定器に関するもので、使用者が誤つて抵抗測
定レンジで電圧を測定したような場合に、測定機
能を破損することなく、使用者に誤使用状態であ
ることを表示または報知することができる抵抗測
定器を提供することを目的とする。[Detailed description of the invention] This invention relates to a resistance measuring device such as a circuit meter that has many measuring functions.If the user accidentally measures voltage with the resistance measuring range, the measuring function will be damaged. It is an object of the present invention to provide a resistance measuring instrument that can display or notify the user that it is being misused.
従来の抵抗測定器においては、例えば、使用者
が誤つて抵抗測定レンジで大きな電圧がかかつた
被測定抵抗の抵抗値を測定したような場合には、
保護ヒユーズで測定機能を保護したり、測定範囲
を越えたことを示す機能を有するものが多かつた
が、使用者に誤使用であることを示す機能を有す
るものはなかつたため、異常状態と正常状態の区
別がつかずに誤測定などの不都合を生じるという
欠点があつた。 With conventional resistance measuring instruments, for example, if the user mistakenly measures the resistance value of a resistor to which a large voltage is applied on the resistance measurement range,
Many of them had a function to protect the measurement function with a protective fuse or to indicate when the measurement range was exceeded, but none had a function to indicate to the user that the measurement was being misused, so it was difficult to distinguish between abnormal and normal conditions. This method has the disadvantage that it is difficult to distinguish between states, resulting in inconveniences such as erroneous measurements.
本考案は上記従来の欠点に鑑みてなされたもの
で、以下、本考案をその実施例を示す図面にもと
づいて説明する。第１図は測定器のブロツク図を
示したもので、１は定電流回路、２は定電流回路
１の異常電圧保護回路、３は抵抗値表示回路、４
は抵抗値表示回路３の異常電圧保護回路、５は異
常表示回路、６は測定端子、７は被測定抵抗であ
る。 The present invention has been devised in view of the above-mentioned drawbacks of the conventional art, and will be described below with reference to drawings showing embodiments thereof. Figure 1 shows a block diagram of the measuring instrument, where 1 is a constant current circuit, 2 is an abnormal voltage protection circuit for constant current circuit 1, 3 is a resistance value display circuit, and 4 is a resistance value display circuit.
5 is an abnormal voltage protection circuit of the resistance value display circuit 3, 5 is an abnormality display circuit, 6 is a measurement terminal, and 7 is a resistance to be measured.
第２図〜第４図は各ブロツクに対応した実施例
を示したもので、第２図において、１は定電流回
路で、オペアンプU1を用い、抵抗R2，R3の電圧
分割によつてその反転入力に基準電圧VS1を与
え、非反転入力には電流出力ISによつて抵抗R1に
発生する電圧VR1を与えることにより、IS＝VS1／R1
なる定電流ISを得ている。Q1はトランジスタ、R4
はトランジスタQ1のベース抵抗である。２は定
電流回路１の異常電圧保護回路であり、D1，D2
はダイオード、Ceは正特性サーミスタである。
この構成において、測定レンジを誤つて測定端子
６のプラス入力が正、マイナス入力が負になる異
常電圧が印加された場合、D1，D2はいずれもカ
ツトオフ状態であるため、定電流回路１は保護さ
れる。また測定端子６の入力に逆方向の電圧が印
加された場合は、ダイオードD2がオンして正特
性サーミスタCeに電流IPが流れ、正特性サーミス
タCeの自己発熱によつて電流IPはわずかな値に減
少するとともに、ダイオードD2によつてダイオ
ードD2の両端の電圧はダイオードD2の順方向電
圧にクランプされるため、定電流回路１はいずれ
の極性の異常電圧に対しても保護される。このよ
うな保護動作の後異常電圧が除去されれば正特性
サーミスタCeは自然冷却されて自動的に復帰し、
再測定が可能となる。 Figures 2 to 4 show examples corresponding to each block. In Figure 2, 1 is a constant current circuit that uses an operational amplifier U 1 and is divided by voltage between resistors R 2 and R 3 . By applying the reference voltage V S1 to the inverting input and applying the voltage V R1 generated across the resistor R1 by the current output I S to the non-inverting input, a constant current I of I S =V S1 /R1 is obtained . I'm getting S. Q 1 is a transistor, R 4
is the base resistance of transistor Q1 . 2 is an abnormal voltage protection circuit for constant current circuit 1, D 1 , D 2
is a diode, and Ce is a positive temperature coefficient thermistor.
In this configuration, if the measurement range is incorrectly selected and an abnormal voltage is applied where the plus input of the measurement terminal 6 is positive and the minus input is negative, both D 1 and D 2 are in the cut-off state, so the constant current circuit 1 is protected. Furthermore, when a voltage in the opposite direction is applied to the input of measurement terminal 6, diode D2 turns on and current I P flows through the positive temperature coefficient thermistor Ce, and the current I P decreases due to self-heating of the positive coefficient thermistor Ce. At the same time, the voltage across the diode D 2 is clamped to the forward voltage of the diode D 2 by the diode D 2 , so the constant current circuit 1 resists abnormal voltages of either polarity. protected. After this protective operation, if the abnormal voltage is removed, the positive temperature coefficient thermistor Ce will cool down naturally and return automatically.
Re-measurement becomes possible.
第３図において、３は被測定抵抗７に定電流IS
を流した結果発生する電圧を抵抗値表示する抵抗
値表示回路で、この回路３はADコンバータ
（AD.C）と液晶表示器LCDとによつて構成され
ている。４は抵抗値表示回路３の異常電圧保護回
路で、抵抗R5とコンデンサC1とによつて構成さ
れている。 In Figure 3, 3 is a constant current I S applied to the resistor 7 to be measured.
This circuit 3 is composed of an AD converter (AD.C) and a liquid crystal display (LCD). Reference numeral 4 denotes an abnormal voltage protection circuit for the resistance value display circuit 3, which is composed of a resistor R5 and a capacitor C1 .
第４図において、５は異常表示回路で、この異
常表示回路５は、次のような動作を行なう。すな
わち、例えば使用者が測定端子６を被測定抵抗７
の両端に接続して被測定抵抗７の抵抗値を測定す
る場合において、使用者が誤つて大きな電圧がか
かつている被測定抵抗７を測定した場合には、測
定端子６が開放状態、すなわち被測定抵抗７が接
続されていない状態で発生する電圧を越える電圧
が測定端子６に印加されることになる。この場合
異常表示回路５は被測定抵抗７の抵抗値RXに比
べて抵抗値が充分大きい抵抗R6、整流ダイオー
ドD3、抵抗R7、コンパレータU2の入力保護用の
ツエナーダイオードZD、および平滑コンデンサ
C2によつて、コンパレータU2の反転入力に電圧
VR7を与え、非反転入力に与えられた基準電圧
VS2とを比較して、VR7＞VS2の条件で発光ダイオ
ードLEDを点灯させて異常状態であることを使
用者に報知する。 In FIG. 4, reference numeral 5 denotes an abnormality display circuit, and this abnormality display circuit 5 performs the following operations. That is, for example, the user connects the measurement terminal 6 to the resistance to be measured 7.
When measuring the resistance value of the resistor to be measured 7 by connecting it to both ends of the resistor, if the user mistakenly measures the resistor to be measured 7 to which a large voltage is applied, the measurement terminal 6 may be in an open state, that is, the resistor to be measured may A voltage will be applied to the measurement terminal 6 that exceeds the voltage that would occur when the measurement resistor 7 was not connected. In this case , the abnormality display circuit 5 includes a resistor R 6 whose resistance value is sufficiently larger than the resistance value R and smoothing capacitor
C 2 causes a voltage to be applied to the inverting input of comparator U 2 .
V R7 and the reference voltage applied to the non-inverting input
V S2 is compared, and under the condition of V R7 > V S2 , the light emitting diode LED is turned on to notify the user of the abnormal state.
なお、前記異常表示は発光ダイオードLEDを
用いなくても、適当なゲート回路を通じて液晶表
示器LCDに表示させることも可能である。 Note that the abnormality display can be displayed on the liquid crystal display (LCD) through an appropriate gate circuit without using a light emitting diode (LED).
以上のように本考案によれば、定電流回路に異
常電圧保護回路を付加するとともに、抵抗値表示
回路を設けたもので、例えば、使用者が誤つて抵
抗測定レンジで大きな電圧がかかつた活性状態の
被測定抵抗の抵抗値を測定した場合や測定端子の
入力に逆方向の電圧が印加された場合には、異常
表示回路が動作するため、従来のように異常状態
と正常状態の区別がつかずに誤測定などの不都合
を生じるということはなくなる。しかもこのよう
な異常状態において定電流回路は異常電圧保護回
路で異常電圧が阻止されて確実に保護され、異常
電圧の除去により保護回路の正特性サーミスタが
自然冷却されて自動復帰するため、リセツト操作
を何ら必要とせずに再測定できるという利点があ
る。 As described above, according to the present invention, an abnormal voltage protection circuit is added to the constant current circuit, and a resistance value display circuit is also provided. When the resistance value of the resistor under test is measured in the active state or when a voltage in the opposite direction is applied to the input of the measurement terminal, the abnormality display circuit is activated, making it impossible to distinguish between abnormal and normal conditions as before. This eliminates inconveniences such as erroneous measurements due to failure to do so. Moreover, in such an abnormal state, the constant current circuit is reliably protected by blocking the abnormal voltage with the abnormal voltage protection circuit, and when the abnormal voltage is removed, the positive characteristic thermistor of the protection circuit is naturally cooled and returns automatically, so that the reset operation is not necessary. This has the advantage of being able to be remeasured without any need for.
第１図は本考案の一実施例を示す抵抗測定器の
ブロツク図、第２図〜第４図は第１図の各ブロツ
ク図に対応した実施例を示す電気回路図である。
１……定電流回路、２，４……異常電圧保護回
路、３……抵抗値表示回路、５……異常表示回
路。
FIG. 1 is a block diagram of a resistance measuring instrument showing one embodiment of the present invention, and FIGS. 2 to 4 are electrical circuit diagrams showing embodiments corresponding to each block diagram of FIG. 1. 1... Constant current circuit, 2, 4... Abnormal voltage protection circuit, 3... Resistance value display circuit, 5... Abnormality display circuit.
Claims (1)
被測定抵抗に生ずる電圧を抵抗値表示回路によつ
て抵抗値表示してなる抵抗測定器において、前記
定電流回路の出力の一端を第１のダイオードと正
特性サーミスタとの直列回路を介して測定端子の
プラス側に接続するとともに、前記定電流回路の
出力の他端と測定端子のマイナス側との接続点を
前記第１のダイオードと正特性サーミスタとの接
続点に第２のダイオードを介して接続してなる異
常電圧保護回路を設けたことを特徴とする抵抗測
定器。 Supply a constant current from a constant current circuit to the resistance to be measured,
In a resistance measuring device that displays a resistance value of a voltage generated in a resistance to be measured using a resistance value display circuit, one end of the output of the constant current circuit is measured via a series circuit of a first diode and a positive temperature coefficient thermistor. The terminal is connected to the positive side of the terminal, and the connection point between the other end of the output of the constant current circuit and the negative side of the measurement terminal is connected to the connection point of the first diode and the positive temperature coefficient thermistor via a second diode. A resistance measuring device characterized by having an abnormal voltage protection circuit connected to the circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7448679U JPS6329259Y2 (en) | 1979-05-31 | 1979-05-31 |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7448679U JPS6329259Y2 (en) | 1979-05-31 | 1979-05-31 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS55174170U JPS55174170U (en) | 1980-12-13 |
| JPS6329259Y2 true JPS6329259Y2 (en) | 1988-08-05 |
Family
ID=29308068
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP7448679U Expired JPS6329259Y2 (en) | 1979-05-31 | 1979-05-31 |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6329259Y2 (en) |
-
1979
- 1979-05-31 JP JP7448679U patent/JPS6329259Y2/ja not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| JPS55174170U (en) | 1980-12-13 |
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