JPH0227600B2 - DOTSUSHIKENKI - Google Patents

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention is useful for continuity testers, particularly for continuity tests of electric detonators, and is useful for conducting continuity tests with the leg wire ends of the electric detonators short-circuited. This relates to a continuity tester that can perform this test.

(Prior art) Conventionally, when performing work or experiments using electric detonators in civil engineering and construction work, mining, resource exploration, scientific experiments, etc., continuity testing of the electric detonators has been required by the Explosives Control Law. It is being

Conventionally, a photovoltaic tester consisting of a photovoltaic cell and an ammeter has been known for conducting continuity tests on electric detonators (Japanese Utility Model Publication No. 24-2664). This continuity tester is
By contacting the two bare wires of the leg wire ends of the electric detonator with the two terminals of the tester,
It is constructed so that a minute current flows from the photovoltaic cell to the electric detonator, the presence or absence of this current is detected, and the presence or absence of continuity is displayed on the ammeter.

(Problems to be Solved by the Invention) Normally, in an electric detonator, the bare wire portions at the end of the leg wires are twisted together and short-circuited to prevent unexpected currents such as leakage current from flowing into the detonator. However, when conducting a continuity test, since the above-mentioned tester was used, it was necessary to open the short-circuited part of the electric detonator. I didn't like it. In addition, it was necessary to short-circuit the wires again after the continuity test, which was a difficult task when there were a large number of wires.

Therefore, in recent years, there has been a strong desire for a tester that can perform electrical detonator continuity tests in a short-circuited state.

An object of the present invention is to provide a continuity tester that satisfies this need and is capable of testing the presence or absence of continuity with the leg terminals short-circuited.

(Means for Solving the Problems) The continuity tester of the present invention includes a sensor coil that is electromagnetically coupled to a loop portion of an object to be measured whose continuity is to be tested, and an AC An oscillator circuit that supplies current, a rectifier circuit that converts the amplitude change of the AC current flowing through the sensor coil into an amplitude change of DC voltage, and compares this DC voltage with a set voltage to determine whether there is continuity in the object to be measured. The device includes a comparison circuit that generates a corresponding detection output, and a display device that is driven by the detection output and indicates the presence or absence of conduction.

(Function) According to the continuity tester of the present invention described above, for example, the presence or absence of continuity can be tested by simply electromagnetically coupling the leg wire end of an electric detonator with the sensor coil while it is short-circuited. Work efficiency is improved and safety is also increased.

(Example) The present invention will be explained below with reference to the drawings.

FIG. 1 is a circuit diagram showing an example of the continuity tester of the present invention, and FIGS. 2a and 2b are a front view and a side view showing its appearance.

In FIG. 1, the continuity tester of the present invention is composed of a sensor coil 1, an oscillation circuit 2, a rectifier circuit 3, a voltage comparator circuit 4, a light emitting diode drive circuit 5, light emitting diodes 6 and 7, a power source 8, and a switch 9. ing. 12 is an electric detonator which is the object to be measured, and 13 and 29 are its terminal loop portion and leg line.

The sensor coil 1 is connected to an oscillation circuit 2. The sensor coil 1 may have any size as long as it can be inserted into the terminal loop portion 13 of the electric detonator, but for practical purposes it should have a diameter of 5 mm or more.
5 cm, preferably about 5 mm to 5 cm in length.

The oscillation circuit 2 includes a transistor 14, a resistor 15,
16 and 17, and capacitors 18 and 19, which together with the sensor coil 1 constitute a Colpitts type oscillation circuit. Oscillation circuit 2
is sensor coil 1 and capacitor 18 and 1
9 oscillates at a resonant frequency determined by sensor coil 1 and generates an alternating current voltage across resistor 17 that is proportional to the alternating current flowing through sensor coil 1 . The oscillation frequency may be any frequency from several KHz to several MHz, but
The higher the frequency, the smaller the sensor coil 1 and condensers 18 and 19, but preferably 100KHz.
~500KHz range.

The rectifier circuit 3 includes a diode 20 and a capacitor 21, and a resistor 17 of the oscillation circuit 2.
The alternating current voltage that occurs between them is rectified and converted to direct current voltage.

The voltage comparison circuit 4 includes a differential amplifier 22 and a resistor 2.
3 and a potentiometer consisting of a variable resistor 24, the DC voltage is compared with a preset voltage from the potentiometer, and two levels are set, high and low, depending on whether the electric detonator is conducting or not. generates a voltage signal. At this time, the set voltage applied to the positive (+) side input terminal of the differential amplifier 22 is set by the variable resistor 24. Rectifier circuit 3 is connected to the negative (-) side input terminal for this voltage.
When the voltage applied from the source is high, a low level voltage signal is generated, and when it is low, a high level voltage signal is generated.

The light emitting diode drive circuit 5 is composed of two transistors 25 and 26. When the voltage signal output from the differential amplifier 22 is at a low level, the transistor 25 becomes conductive to cause the red light emitting diode 6 to emit light, and the voltage increases. When the signal is at a high level, the transistor 26 is made conductive and the green light emitting diode 7 emits light.

In the figure, 8 indicates a power supply, and 9 indicates a switch. The power supply 8 only needs to be sufficient to operate each circuit, and is preferably in the range of 4.5 to 9V.

FIGS. 2a and 2b are diagrams showing the external appearance of a continuity tester incorporating the above-mentioned circuit, and the circuit is
Although the sensor coil 1 is housed inside, the sensor coil 1 protrudes and constitutes a detection section. The detection section of the sensor coil is protected by a sensor coil cover 11. A red light emitting diode 6 and a green light emitting diode 7 are provided on the front surface of the casing 10, respectively, to display at a glance whether or not the electric detonator 12 is conductive. Further, a switch 9 is also provided on this front surface. Reference numeral 13 indicates a terminal loop portion of the electric detonator; 2, 7, 28, and 29 indicate the detonator, electric bridge, and leg wire of the electric detonator, respectively; and 30 indicates a short-circuit portion of the leg wire.

In determining the presence or absence of continuity of the electric detonator, first, the AC voltage of the oscillation circuit 2 when the terminal loop portion 13 of the electric detonator is not inserted into the sensor coil 1 is rectified by the rectifier circuit 3 to obtain a DC voltage [voltage The positive (+) side input of the comparator circuit 4], the voltage input to the negative (-) side of the voltage comparator circuit 4 is connected to the variable resistor 2.
4 to set the output voltage of the voltage comparator circuit 4 to a low level so that the red light emitting diode 6 emits light.

The terminal loop section 13 of the electric detonator is then inserted into the sensor coil 1 as shown in FIG. If the electric detonator 12 is conductive, the electric detonator becomes a secondary circuit for the sensor coil 1 and becomes a load for the oscillation circuit 2, so that the alternating current flowing through the sensor coil and the oscillation circuit decreases, and the alternating current voltage appearing across the resistor 17 , the DC voltage output from the rectifier circuit 3 decreases, and the negative (-) side input voltage of the voltage comparator circuit 4 becomes lower than the positive (+) side input voltage. As a result, the output voltage of the voltage comparator circuit 4 decreases. becomes a high level, and the green light emitting diode 7 emits light, which can be confirmed. On the other hand, if there is no continuity in the electric detonator 12, the electric detonator does not constitute a secondary circuit for the sensor coil 1;
In order not to become a load on the oscillation circuit 2, the AC voltage generated across the resistor 17 of the oscillation circuit 2 does not decrease, and the red light emitting diode 6 emits light, as in the case where the terminal loop portion 13 of the electric detonator is not inserted into the sensor coil 1. do.

Therefore, the presence or absence of continuity of the electric detonator 12 can be determined by inserting the terminal loop part 29 of the electric detonator into the sensor coil 1 of the continuity tester and turning on the switch 9. If there is continuity, the green light emitting diode 7 will light up. If it lights up and there is no continuity, the red light emitting diode 6
lights up, so you can easily determine whether there is continuity.

The following experiment was conducted using the continuity tester for the circuit shown in FIG. However, in the circuit used, the dimensions of sensor coil 1 are 8 mm in diameter.
So, use one with a length of 1 cm, set the oscillation frequency of oscillation circuit 2 to 200KHz, and set the voltage of voltage comparison circuit 4 to a low level voltage signal of 3V or less.
The high level voltage signal was set to 3V or higher, and the power supply 9 was set to 6V.

Using the continuity tester mentioned above, the leg line length is determined to have continuity for 50 shots and no continuity for 50 shots.
Continuity was measured for 100 rounds of a 1.8m electric detonator.

As a result, we were able to correctly determine continuity for all 100 shots without a single error.

Continuity was then similarly measured for 100 detonators each with leg lengths of 5 cm, 5 m, 10 m, and 15 m.

As a result, as before, we were able to correctly determine continuity for all 400 shots without making a single error.

In this case, the current induced in the conductive legs of the electric detonator is less than 1 mA, which is less than 1/300 of the minimum firing current of an electric detonator, approximately 300 mA, and the test can be carried out safely. can be done.

The present invention is not limited to the embodiments described above, but can be modified in many ways. For example, a display device that indicates the presence or absence of continuity is not limited to a light-emitting diode, but can also be a visual display device such as a meter or liquid crystal display device, or an auditory display device such as a buzzer, but the configuration is simple. It is preferable to use a light emitting diode that can clearly identify the presence or absence of conduction.

Furthermore, in the above-described embodiment, the terminal loop section is inserted into the sensor coil to electromagnetically couple them. Electromagnetic coupling can also be achieved by inserting or sandwiching between wires.

〔Effect of the invention〕

The continuity tester of the present invention has the following features, especially when used as a continuity tester for electric detonators.

(1) Compared to conventional continuity testers, continuity testing can be performed with the terminals of the legs of the electric detonator short-circuited (simply by expanding the terminals to form a loop), which significantly saves work. can be converted into

(2) Compared to conventional continuity testers, because the bare wires of the legs of the electric detonator are not directly contacted with the terminals of the tester, the circuit of the tester and the electric detonator are not directly connected, and the circuit Even if the detonator fails, there is no large current flowing through the detonator, making it safe.

(3) Compared to conventional continuity testers, the terminals of the leg wires of electric detonators do not need to be bare wires; they have loops, and if there is a short circuit inside the vinyl sheathing, continuity is maintained as is. Since the test can be carried out, there is no stray/leakage current or static electricity flowing in, making it safe and particularly preferable from a safety standpoint.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an example of the continuity tester of the present invention, and FIGS. 2a and 2b are a front view and a side view showing the external appearance of the continuity tester incorporating the same. 1... Sensor coil, 2... Oscillation circuit, 3...
... rectifier circuit, 4 ... voltage comparison circuit, 5 ... light emitting diode drive circuit, 6 ... red light emitting diode,
7... Green light emitting diode, 8... Power supply, 9...
Switch, 10... Case, 11... Sensor coil cover, 12... Electric detonator, 13... Terminal loop section, 14... Transistor, 15, 16, 1
7... Resistor, 18, 19... Capacitor, 20
...Diode, 21...Capacitor, 22...
... Differential amplifier, 23 ... Resistor, 24 ... Variable resistor, 25, 26 ... Transistor, 27 ... Explosive charge, 28 ... Electric bridge, 29 ... Leg wire, 30 ... Short-circuit part of leg wire.

Claims (1)

[Claims] 1. A sensor coil that is electromagnetically coupled to the loop part of the object to be tested for continuity, an oscillation circuit that is connected to this sensor coil and supplies alternating current to it, and changes in the amplitude of the alternating current that flows through the sensor coil. a rectifier circuit that converts the DC voltage into an amplitude change in the DC voltage, a comparator circuit that compares this DC voltage with a set voltage and generates a detection output corresponding to the presence or absence of continuity of the DUT, and a , and a display device that indicates the presence or absence of continuity.