JPH04366773A - Measuring method for microcurrent - Google Patents

Abstract

PURPOSE:To enable measurement of microcurrent at low cost and in a short time without using shielding wires by measuring the potential of the anode part of an internal power supply as earth voltage and that of the cathode part as negative rated voltage. CONSTITUTION:The potential of the anode part of an internal power supply 8 is measured as earth voltage and the potential of the cathode part is measured as negative rated voltage; i.e., during the measurement, the earth voltage is generated at an anode circuit 4 and at the anode circuit 4 of a measuring apparatus 7 and the storage of charge between the circuit 4 and the earthing is avoided. Thereby charge current is not allowed to flow and so the rated voltage can be quickly applied to a subject 1 to be measured and microcurrent can be measured in a short time.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a measuring method for measuring minute currents in an object to be measured.

0002

2 and 3 are conventional microcurrent measuring circuit diagrams. In FIG. 2, 1 is an object to be measured, 2 is a measuring device, 3 is a cathode circuit, 4 is an anode circuit for current measurement, 8 is an internal power supply of the measuring device 2, and 9 is a device that measures the minute current flowing through the anode circuit 4. It is a measuring instrument. In FIG. 3, 5 is a guard circuit that shields the anode circuit 4, and 6 is a measuring device to which the guard circuit 5 can be added.

Next, the operation will be explained. In FIG. 2, when measuring the current of the object to be measured 1, a rated voltage is applied by the internal power supply 8 of the measuring device 2, and the minute current flowing through the anode circuit 4 is measured by the measuring device 9. At this time, the internal power supply 8 of the measuring device 2 fixes the cathode circuit 3 side to the ground potential. Further, in FIG. 3, the guard circuit 5 is fixed at the same potential as the anode circuit 4, thereby reducing the charge accumulated in the anode circuit 4.

0004

[Problems to be Solved by the Invention] In the conventional measurement circuit, when measuring a minute current of the object to be measured 1, the cathode circuit portion of the measuring device 2 and the anode circuit 4 connecting the measuring device 2 and the object to be measured 1 are used.
Since there is a capacitance between the part 1 and ground, and the object to be measured has high impedance during minute current measurement, the time constant is large and it takes a considerable amount of time for the object to be measured 1 to reach the rated voltage. There was a problem that it was necessary. Furthermore, in order to alleviate this problem, a guard circuit 5 is provided as shown in FIG. 3, but the internal circuit of the measuring device 6 becomes complicated and an expensive shielded wire is required. The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a microcurrent measuring method that can measure microcurrents inexpensively and in a short time without using shielded wires.

[0005]

[Means for Solving the Problems] The present invention provides a microcurrent measurement method in which the internal power supply voltage of a measuring device is applied to a closed loop with a measurement device to measure a microcurrent flowing through the measurement device. The potential of the anode portion is set to the ground voltage, and the potential of the cathode portion is measured as a negative rated voltage. Further, the potential of the cathode portion of the internal power source is set to a negative voltage so that the potential of the anode portion of the internal power supply approaches the ground voltage, and the measurement is performed by applying the rated voltage.

[0006]

[Operation] According to the present invention, since the anode potential is equal to or as close as possible to the ground potential, the charging current in the anode circuit within the measuring device and the anode circuit leading to the object to be measured is small.
The rated voltage can be applied to the object under test in a short time.

[0007]

Embodiments Hereinafter, embodiments of the present invention will be explained with reference to the drawings. FIG. 1 is a measurement circuit diagram illustrating the measurement method according to the present invention, in which 1 is an object to be measured, 3 is a cathode circuit, 4 is an anode circuit for current measurement, 7 is a measurement device with the anode circuit 4 side grounded, 8 is an internal power supply of the measuring device 7, and 9 is a measuring device for measuring the minute current flowing through the anode circuit 4.

Next, the operation will be explained. During measurement, the anode circuit 4 and the anode circuit 4 of the measuring device 7 are at ground potential, and no charge is accumulated between them and the ground. This results in
Since the charging current no longer flows, the rated voltage can be quickly applied to the object to be measured 1, making it possible to measure minute currents in a short time.

In the above embodiment, the anode circuit 4 is set to be equal to the ground potential, but if the anode circuit 4 cannot be set to the ground potential, the potential of the anode circuit 4 is set to be as close to the ground potential as possible. A similar effect can be achieved by setting the potential of the cathode circuit 3 to a negative potential and applying the rated voltage to the object to be measured 1.

0010

As described above, according to the present invention, since the anode circuit is set to the ground potential or a potential close to the ground potential for measurement, the measuring device can be made inexpensive, and highly accurate measurements can be carried out in a short time. The effect is that it can be done on time.

[Brief explanation of drawings]

FIG. 1 is a measurement circuit diagram showing an embodiment of a microcurrent measurement method according to the present invention.

FIG. 2 is a diagram showing an example of a conventional measurement circuit.

FIG. 3 is a diagram showing another example of a conventional measurement circuit.

[Explanation of symbols]

1 Object to be measured 3 Cathode circuit 4 Anode circuit 7 Measuring device 8 Internal power supply 9 Measuring equipment

Claims (2)

[Claims] 1. A microcurrent measurement method in which a microcurrent flowing through a measurement device is measured by applying an internal power supply voltage of a measuring device to a closed loop with the measurement device, wherein the potential of an anode portion of the internal power supply is set to a ground voltage. , and a microcurrent measurement method that measures the potential of the cathode part as a negative rated voltage. 2. A microcurrent measurement method in which an internal power supply voltage of a measuring device is applied to a closed loop with a measurement target to measure a microcurrent flowing through the measurement target, wherein the potential of the anode portion of the internal power supply is set to a ground voltage. A microcurrent measurement method in which the potential of the cathode is set to a negative voltage so that the potential of the cathode can be brought closer, and the rated voltage is applied and measured.