JPH08248079A - Electric field detector - Google Patents

Abstract

PURPOSE: To measure an electric field to be applied to the vicinity of a wiring pattern on a printed circuit board. CONSTITUTION: An electric field detector 1 comprises a monopole antenna 2 for detecting an electric field, a converter 3 for converting the field detected by the antenna 2 into a digital signal, a display unit 4 for outputting the output signal of the converter 3 as auditory information, and a battery 5 for supplying power to the unit 4 and the converter 3, wherein the converter 3, the unit 4 and the battery 5 are contained in the same housing 6, and the antenna 2 protrudes from the housing 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric field detecting device, and more particularly to an electric field detecting device for detecting static electricity which causes malfunction of a digital circuit using an integrated circuit or a strong electric field emitted from the outside of the device.

[0002]

2. Description of the Related Art Conventionally, detection of the strength of an electric field applied to a wiring pattern connected to an integrated circuit mounted on a printed wiring board has been carried out in the form shown in FIG.
That is, the probe cable 61 of the oscilloscope 60 is inserted into the device to be measured 50, the electric field probe 62 is arranged near the printed wiring board 51 in the device to be measured 50,
In this state, static electricity was discharged by the discharge gun 70, and the strength of the electric field applied to the wiring pattern (not shown) of the printed wiring board 51 was measured by the oscilloscope 60.

Further, as a technique for detecting an electric field generated by static electricity, there is an electrostatic discharge detection device described in Japanese Patent Laid-Open No. 4-289462. This electrostatic discharge detection device receives an electromagnetic wave with a monopole antenna, amplifies and detects the electromagnetic wave, compares the time width of the received electromagnetic wave with a reference time width, and determines whether the received electromagnetic wave is an electromagnetic wave due to static electricity. Whether or not it is determined, and if the determination result is due to static electricity, it is displayed.

[0004]

However, in the electric field detecting device described in FIG. 5, the probe cable 61 having a long length is provided between the oscilloscope 60 and the electric field probe 62.
Are connected using. Therefore, an electromagnetic field generated from the discharge gun 70 also induces an electric field in the probe cable 61, and this electric field is transmitted to the oscilloscope 60. Therefore, it is difficult to accurately measure the electric field waveform applied to the vicinity of the wiring pattern of the printed wiring board 51. Further, since the electric field probe 62 is inserted into the device under test 50, the device under test 50 cannot be closed completely, the connection of the device under test 50 becomes insufficient, and the printed wiring board 5
There was a problem that the electric field applied in the vicinity of the first wiring pattern was different from the actual usage state.

Further, since the electrostatic discharge detection device according to Japanese Patent Application Laid-Open No. 4-289462 cannot detect the electric field applied in the vicinity of the wiring pattern of the printed wiring board, the countermeasure and the device for improving the electrostatic resistance of an actual electronic circuit are not provided. There is a problem that it cannot be used as a measure for improving the proof stress against strong electric field irradiation.

Therefore, the present invention has been made to solve the above-mentioned conventional problems, and an object thereof is an electric field detecting device capable of accurately measuring an electric field applied only in the vicinity of a wiring pattern on a printed wiring board. To provide.

[0007]

In order to achieve such an object, an electric field detecting apparatus according to the present invention comprises a monopole antenna for detecting an electric field and a conversion for converting the electric field detected by the monopole antenna into a digital signal. Section, a display section that outputs an output signal of the conversion section as visual or auditory information, and a battery that supplies power to the display section and the conversion section. The battery, the conversion section, and the display section are in the same housing. , And the monopole antenna is formed by projecting from the housing.

[0008]

In the present invention, the converter, the display and the battery are housed in the same housing, and the monopole antenna is projected on this housing, so that the electric field of the portion to be measured can be eliminated without the need for a cable drawn to the outside. Only can be detected.

[0009]

Embodiments of the present invention will now be described in detail with reference to the drawings. 1 is a circuit block diagram for explaining an embodiment of an electric field detecting device according to the present invention, and FIG. 2 is a perspective view for explaining an electric field detecting method by the electric field detecting device of FIG. Hereinafter, description will be given with reference to these drawings.

In FIG. 1, an electric field detecting device 1 is a monopole for detecting an electric field in the vicinity of a detected circuit pattern 53 formed on a printed circuit board 51 shown in FIG. The antenna 2, the conversion unit 3 that converts the input signal from the monopole antenna 2 into a digital signal, the display unit 4 that outputs the output signal from the conversion unit 3 as visual information, the conversion unit 3 and the display unit 4 And a battery 5 for supplying power to.

Then, the battery 5, the conversion unit 3 and the display unit 4
Are housed in the same housing 6, and the monopole antenna 2 is projectingly provided on the housing 6. The monopole antenna 2 for detecting an electric field is formed of a thin rod-shaped conductor, and is a protective cover 2a in which the outer peripheral surface of the conductor is formed of an insulator in order to avoid a short circuit with the metal portion in the printed wiring board 51 described above. It is covered and configured.
The monopole antenna 2 is formed so as to be expandable and contractible, and has a structure in which its length can be changed depending on the place where it is installed in the device.

Further, the conversion unit 3 includes a monopole antenna 2
A variable resistor 3a as a sensitivity adjuster for adjusting and inputting an electric signal corresponding to the magnitude of the electric field detected by the diode, and an electric signal output from the variable resistor 3a as a diode,
An IC circuit 3b for detecting a signal using a transistor and a stray capacitance and converting it into a digital signal is configured.

Generally, the electric field generated by electrostatic discharge is about 1
0MHz-800MHz, International Standard IEC-801-3
In the electric field irradiation test specified in 1), an electric field having a frequency band of about 30 MHz to 1 GHz is irradiated. Converter 3
Is subjected to sensitivity adjustment by the variable resistor 3a, converted into a digital signal by the IC circuit 3b, and output.

The display unit 4 is a monostable multivibrator 4
It is composed of a and a buzzer 4b. The digital signal output from the conversion unit 3 by the electric field is extended by the monostable multivibrator 4a (pulse extension circuit) to a time width that can be heard by the human ear, and a buzzer sound is generated by the buzzer 4b. It should be noted that the buzzer 4b may be replaced with a light emitting diode for confirmation by light. The housing 6 is formed of a molded body of a metal plate such as aluminum that can prevent electromagnetic noise.

FIG. 3 is a diagram for explaining a state in which an electrostatic test is carried out using the electric field detecting device having such a configuration.
In FIG. 3, the printed wiring board 51 in which the IC 52 is mounted is housed and the printed wiring board 5 in the device under test 50 is accommodated.
The electric field detection device 1 is arranged on the surface 1. Then, static electricity is discharged to the device under test 50 by the discharge gun 70, and a sound generated by the buzzer 4b provided in the electric field detecting device 1 is heard.

If this buzzer does not sound, it can be determined that the detected wiring pattern of the printed wiring board 51 does not have an electric field of a magnitude that causes the IC 52 to malfunction. In addition, if a buzzer sounds, IC5 is detected in the detected wiring pattern.
Since an electric field of a magnitude that causes the malfunction of 2 is applied, it is necessary to take measures such as increasing the number of screwing points connecting the metal plates forming the housing of the device under test 50 or providing a shield plate. Therefore, since the strength of the electric field can be compared before and after the measures against the housing, the effect of the measures due to the connection between the metal plates can be easily confirmed.

FIG. 4 shows the above-mentioned international standard IEC-801.
It is a figure which shows the state in the electric field irradiation test prescribed | regulated by -3. In FIG. 4, the radiation antenna 41 generates a strong electric field and irradiates the device under test 50 with the strong electric field. Each printed wiring board 5 mounted in the device under test 50
An electric field detection device 1 is attached to each of 1 to detect an electric field in each portion. When a plurality of electric field detecting devices 1 are used at the same time, the buzzers 4b used for the electric field detecting devices 1 are set to generate different sounds.

[0018]

As described above, according to the electric field detecting device of the present invention, by providing the antenna on the housing, the probe cable can be eliminated and the battery can be used as the power source. The power cable can be eliminated. Therefore, it is possible to detect the electric field applied to the monopole antenna by suppressing the electric field entering the device from the outside as much as possible, and further it is possible to downsize the entire structure and install it in a narrow place.

Further, according to the electric field detecting device of the present invention, since there is no external cable and the confirmation can be performed by hearing, the test can be performed with the housing of the device under test completely closed. The reproducibility is improved, and it is possible to measure the part that cannot be seen from outside.

Further, according to the electric field detecting device of the present invention, by providing a sensitivity adjuster in the input circuit of the converting section, it is possible to obtain an extremely excellent effect that the effect of the electric field countermeasure can be quantitatively judged. To be

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration according to an embodiment of an electric field detecting device according to the present invention.

FIG. 2 is a perspective view for explaining an electric field detecting method by the electric field detecting device according to the present invention.

FIG. 3 is a diagram for explaining an electrostatic test of the electric field detection device according to the present invention.

FIG. 4 is a perspective view for explaining an electric field irradiation test of the electric field detecting device according to the present invention.

FIG. 5 is a diagram for explaining a conventional electric field detection method.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Electric field detection device, 2 ... Monopole antenna, 2a ... Protective cover, 3 ... Conversion part, 3a ... Variable resistor, 3b ... IC
Circuit, 4 ... Display unit, 4a ... Monostable multivibrator,
4b ... Buzzer, 5 ... battery, 6 ... enclosure.

Claims (4)

[Claims] 1. A monopole antenna for detecting an electric field,
A converter that converts the electric field detected by the monopole antenna into a digital signal, a display unit that outputs the output signal of the converter as visual or auditory information, and a battery that supplies power to the display unit and the converter. An electric field detection device comprising: the conversion unit, the display unit, and the battery housed in the same housing, and the monopole antenna protruding from the housing. 2. The sensitivity converter according to claim 1, wherein the conversion unit has a sensitivity adjuster for adjusting and inputting an electric signal corresponding to a magnitude of an electric field detected by the monopole antenna into an input circuit. Electric field detection device. 3. The display unit according to claim 1, wherein the display unit includes a pulse expansion circuit that expands a pulse of an output signal of the conversion unit, and a display that notifies the output of the pulse expansion circuit by light or sound. Characteristic electric field detection device. 4. The electric field detecting device according to claim 1, wherein the monopole antenna has a function of expanding and contracting.