JPH04118672U - resistance measuring device - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a resistance measuring device with faster measurement response speed. [Configuration] A constant current supply circuit 11 for passing a constant current i through the object to be measured Rx, and a resistance value corresponding to the voltage Vx 2 that is actually measured when a constant current i is passed through the object to be measured Rx can be displayed. in,
A resistance measurement circuit 21 having a switch circuit 25 that can control the opening and closing of the circuit between it and the constant current supply circuit 11, and a connection to a device to be measured that allows the resistance measurement circuit 21 to send a control current to the switch circuit 25. - A resistance measuring device equipped with a disconnection detection circuit 35. [Effect] By preventing open circuit voltage from being applied to the resistance measurement circuit 21 side when the object to be measured Rx is disconnected, the measured value obtained when the object to be measured Rx is connected is stabilized to the true value. The measurement response speed required up to this point can be increased, and the resistance measurement work can be speeded up.

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

This idea works when the object under test is not connected, that is, when the measurement resistance is infinite. Connect the object to be measured under the condition that the This invention relates to a resistance measuring device that has a faster measurement response speed.

0002

[Conventional technology]

Some resistance measuring devices pass a constant current through the object being measured and measure the voltage at that time. After calculating the resistance in relation to this measured voltage value, measure and display the resistance value of the object to be measured. There are also things like digital multimeters that do this.

0003 Figure 2 shows a schematic diagram of a measurement circuit using the four-terminal method based on the above type of resistance measurement device. This is an example of the main points.

0004 According to the figure, the entire process consists of a constant current flowing to the object under test Rx based on the reference voltage Vref. A constant current supply circuit 51 capable of supplying constant current i and a constant current supply circuit 51 capable of supplying constant current i to the object to be measured Rx. It is possible to measure voltage and display the resistance value calculated in relation to the actual measured voltage. It is composed of a resistance measuring circuit 61.

[0005] Of these, the constant current supply circuit 51 is a reference voltage supply circuit for generating a reference voltage Vref. Output to the subsequent stage based on the relationship between the pressure generating circuit 52 and the reference resistor 56 provided in the circuit. Comparison and amplification means 53 for controlling the voltage and output control from this comparison and amplification means 53 The voltage is converted into a current, and the constant current i is passed through the current terminals 57 and 58 to the object to be measured R. x .

[0006] Further, the resistance measuring circuit 61 is configured to measure the resistance that occurs when the constant current i is supplied to the object to be measured Rx. voltage measurement terminals 62 and 63 for detecting and taking in the voltage Vx, and these voltages. The voltage Vx taken in through the measurement terminals 62 and 63 is measured, and the actual measured voltage at that time is Voltage measurement/resistance measurement using a voltmeter, etc. that can display the resistance value calculated in relation to the It is formed by a resistance value display means 64.

[0007]

[Problem that the idea aims to solve]

By the way, the conventional example shown in FIG. 2 is constructed entirely of a relatively simple circuit. Although it is superior in that it can perform When Rx is in the disconnected state, the voltage measurement/resistance value display means 64 side is in the open state. It has become.

[0008] Therefore, in some cases, the open circuit voltage of the current source may be on the side of the voltage measurement/resistance value display means 64. will be applied directly.

[0009] In this way, excessive input voltage is applied to the voltage measurement/resistance value display means 64. When the measured object Rx is connected under a power condition, the voltage in this excessive input condition level to the normal measured voltage level, and during this drop This takes a lot of time, which results in a slow measurement response speed and makes it difficult to convert the measured value to the true value. The drawback is that it takes a lot of time to stabilize, slowing down the resistance measurement process. It was convenient.

0010

[Means to solve the problem]

This idea was made in view of the above-mentioned problems seen in the prior art. The configuration features a constant current flowing through a pair of current terminals to the connected device under test. A constant current supply circuit to supply a constant current, and a pair of voltages when a constant current is applied to the object to be measured. A resistance measurement circuit that can display the resistance value calculated in relation to the voltage between the measurement terminals. Detects the voltage between the current terminals and determines whether the voltage is constant. A device under test connection/disconnection detection circuit that generates an output when the value exceeds the value is provided, and the output of the circuit is The current to be measured is connected between the current terminals via a switch circuit that is controlled to open and close by force. If something is connected, close the circuit and pre-empt the generated voltage between the voltage measurement terminals. input to the resistance measurement circuit, and if it is not connected, open the circuit and connect the switch phase. The purpose is to short-circuit each other.

[0011]

[Effect]

Therefore, when the device under test is not connected, it is incorporated into the resistance measurement circuit and The switch circuit that is interlocked with the measurement object connection/disconnection detection circuit is a constant current supply circuit. This opens the circuit between the switch and the resistance measurement circuit and simultaneously shorts the switches. , it is possible to prevent the application of the open circuit voltage of the current source to the resistance measuring circuit side.

0012 Therefore, if a new device is connected by replacing the device under test, etc. In some cases, the short-circuit voltage level can be brought to the normally measured voltage level in a relatively short period of time. The voltage can be increased, thus preventing excessive input voltage levels as before Unlike when the voltage is dropped from the voltage level to the normal measurement voltage level, the measured value settles to the true value. The measurement response speed can be increased by shortening the time it takes to establish a measurement.

[0013]

【Example】

Hereinafter, embodiments of this invention will be described based on the drawings. FIG. 1 is a circuit diagram showing an embodiment of this invention.

[0014] According to the figure, the entire system is designed to flow a constant current i to the connected device under test Rx. a constant current supply circuit 11 for measuring the object to be measured Rx, and a constant current supply circuit 11 for measuring the object to be measured Resistance measurement circuit 2 that can display the resistance value obtained in response to the measured voltage 1, and performs circuit opening/closing control between the constant current supply circuit 11 and the resistance measurement circuit 21. It is equipped with a device under test connection/disconnection detection circuit 35 that generates a control current to It is designed with a focus on

[0015] Of these, the constant current supply circuit 11 supplies a pair of currents to the connected device under test Rx. It is possible to generate a reference voltage Vref 1 for flowing a constant current i through terminals 17 and 18. and the reference voltage V applied to the non-inverting input terminal side. Voltage Vr generated by constant current i flowing through reference resistor 16 with ref 1 installed in the circuit is applied to the inverting input terminal side and compared, and the reference voltage Vref 1 and the voltage Vr are equal. A first comparative amplification means generates a voltage in the semiconductor element 14 located at the subsequent stage so that stage 13 and converts the output voltage from the first comparison amplification means 13 into a current to generate a constant current i. Is it a transistor or the like that can supply current to the object under test Rx via current terminals 17 and 18? It is formed of a semiconductor element 14 consisting of the following. In addition, the code|symbol 15 is the said semiconductor element. 14 is shown.

[0016] Further, the resistance measuring circuit 21 generates a signal when a constant current i is supplied to the object to be measured Rx. Voltage measurement terminals 22 and 23 for taking in the generated voltage Vx 2, and these voltage measurement terminals a power measuring section that measures the voltage Vx2 taken in through terminals 22 and 23; Voltage measurement consisting of a display section that converts the actual measured voltage into the corresponding resistance value and displays it. - A resistance value display means 24 is provided.

[0017] Moreover, the voltage measurement terminals 22, 23 and the voltage measurement/resistance value display means 24 are connected to each other. In between, opening/closing control of the circuit between the constant current supply circuit 11 and the voltage measurement terminal is provided. 22, 23 and the voltage measurement/resistance value display means 24 and the opening/closing control of the circuit is performed simultaneously. A switch circuit 25 is interposed that allows the object to be measured Rx to connect. state, the constant current supply circuit 11 and the resistance measurement circuit 21 are closed, and the The constant current supply circuit 11 and the resistance measurement circuit 21 are opened when the object Rx is disconnected. The switch 28 and the switch 31 can be controlled to short-circuit at the same time as the switch 28 and the switch 31 are connected. It is formed by

[0018] The switch circuit 25 in this case can control opening and closing of a predetermined circuit. Any suitable configuration can be adopted. This will be explained in detail according to the illustrated example. Then, the circuit between the voltage measurement terminals 22 and 23 and the voltage measurement/resistance value display means 24 A switch 28 and a switch 31 are arranged separately, and these switches Directly connected to the voltage measurement terminal 22 between the switches 28 and 31 and the voltage measurement terminals 22 and 23 In addition to the conduction contact 26 and the open contact 27 that connect to the voltage measurement terminal 23, The point 29 and the open contact 30 are arranged in a corresponding pair. .

[0019] In addition, the switches 28 and 31 are connected to the device under test connection/disconnection detection circuit 35 side. Conductivity with the conduction contact 26 when there is no control current input to the switch circuit 25 side The contact point 29 is contacted separately, and the side of the device under test connection/disconnection detection circuit 35 is contacted. When there is a control current input from the open contact 27 and the open contact 30, respectively. They are arranged so that they can be switched to contact each other separately.

[0020] In this case, the open contacts 27 and 30 are directly connected to each other. There is a short circuit.

[0021] On the other hand, the device under test connection/non-connection detection circuit 35 detects when the device under test Rx is connected. It is possible to generate a reference voltage Vref 2 at the same level as the maximum voltage Vx 1 during normal measurement. The set second reference voltage generation circuit 36 and the voltage applied to the inverting input terminal side. The quasi voltage Vref 2 is applied to the non-inverting input terminal when the device under test Rx is connected. A second comparison amplification circuit compares and outputs the maximum voltage Vx1 during normal measurement under the stage 37 and a forward voltage output based on the output voltage from this second comparing and amplifying means 37. It is formed with a current control element 38 such as a diode that allows current to flow only in the direction. After the current control element 38, an attached resistor 39 is connected to the resistance measuring circuit 21. The switch circuit 25 is connected to the side of the switch circuit 25.

[0022] Next, regarding this invention constructed as described above, first, the object to be measured Rx The effect will be explained in the case where is connected in the circuit.

[0023] That is, when the object to be measured Rx is in a connected state, the constant current supply circuit 11 has no current. During normal measurement, a voltage with a maximum voltage of Vx 1 is generated (hereinafter, the generation in this case is (The raw voltage is Vx 1).

[0024] This generated voltage Vx 1 is simultaneously applied to the device under test connection/disconnection detection circuit 35 side. is generated and applied to the non-inverting input terminal side of the second comparison and amplification means 37.

[0025] However, in this case, the second comparison and amplification means 37 has a relationship of Vref 2≧Vx 1. and Vx 1 is on the non-inverting input terminal side, and Vref 2 is on the inverting input terminal side. As a result, the output voltage also becomes 0V and no current flows, so the resistance The switch circuit 25 in the resistance measurement circuit 21 connects the switch 28 to the conduction contact 26, The switches 31 are connected to the constant current supply circuit 11 by contacting the conduction contacts 29, respectively. The voltage Vx 1 is measured by the voltage measurement/resistance value display means 2. 4 side, display the corresponding resistance value (true value), and perform resistance measurement work. can be done.

[0026] On the other hand, the object to be measured Rx, whose measurement resistance is infinite, is not connected to the circuit. In this case, an open-circuit voltage of the current source occurs, and this open-circuit voltage It also occurs on the connection detection circuit 35 side at the same time, and the non-inverting input terminal of the second comparison amplification means 37 It will be applied to the child side.

[0027] In this case, the open circuit voltage applied to the non-inverting input terminal side is Since it is sufficiently larger than the applied reference voltage Vref 2, the second comparison and amplification means 37 is Then, current flows to the switch circuit 25 side in the resistance measurement circuit 21, and the switch Activate the circuit 25, set the switch 28 to the open contact 27, and switch 31 to the conductive contact. 30 respectively to open between the constant current supply circuit 11 and the resistance measurement circuit 21. At the same time, switch 28 and switch 31 can be short-circuited.

[0028] For this reason, an open circuit is provided on the side of the voltage measurement/resistance value display means 24 in the resistance measurement circuit 21. It is possible to prevent the overvoltage that is the discharge voltage from inputting, and therefore This speeds up the measurement response speed when connecting an object Rx and shortens the time until it stabilizes to the true value. can be done.

[0029]

[Effect of the idea]

As described above, according to this invention, when the device under test is not connected, Built into the resistance measurement circuit in conjunction with the fixed object connection/disconnection detection circuit. The switch circuit consists of opening the circuit between the constant current supply circuit and the resistance measurement circuit, and Since both circuits can be shorted at the same time, there is no need to create an excessive open circuit on the resistance measurement circuit side. Application of discharge voltage can be reliably prevented.

[0030] Therefore, if a new device is connected by replacing the device under test, etc. If the Therefore, the normal measurement voltage can be reduced from the excessive input voltage level as in the conventional method. Unlike when the voltage is dropped to the voltage level, the time it takes for the measured value to stabilize to the true value You can quickly perform resistance measurement tasks by shortening the measurement time and increasing measurement response speed. .

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an embodiment of this invention.

FIG. 2 is a circuit diagram as an example employed in a conventional resistance measuring device.

[Explanation of symbols]

11 Constant current supply circuit 12 First reference voltage generation circuit 13 First comparison and amplification means 14 Semiconductor element 17 Current terminal 18 Current terminal 21 Resistance measurement circuit 22 Voltage measurement terminal 23 Voltage measurement terminal 24 Voltage measurement/resistance value display means 25 Switch circuit 35 DUT connection/disconnection detection circuit 36 Second reference voltage generation circuit 37 Second comparison and amplification means 38 Current control element Rx Object to be measured

Claims (1)

[Scope of utility model registration request] 1. A constant current supply circuit for supplying a constant current to a connected object to be measured through a pair of current terminals, and a pair of voltage measuring terminals when a constant current is applied to the object to be measured. A resistance measuring device equipped with a resistance measuring circuit capable of displaying a resistance value calculated in relation to a voltage between the current terminals, detects the voltage between the current terminals, and generates an output when the voltage is above a certain value. A device under test connection/disconnection detection circuit is provided, and a switch circuit whose opening/closing is controlled by the output of the circuit is provided to close the circuit when a device under test is connected between the current terminals. and inputs the voltage generated between the voltage measurement terminals to the resistance measurement circuit, and if the circuit is not connected, the circuit is opened and the switches are short-circuited.