Charged Human Body Research Articles

Electrostatically Induced Voltage in Metal Box When Charged Object Like Hand Moves Away From the Box to Three Directions

When a charged human body stands up from a chair or walks in a room using an air conditioner, a malfunction or failure of electronic devices is caused occasionally by the static electricity. When the charged human body operates the electronic device by a charged hand, an instantaneous electrostatically high induced voltage is generated in the metal case of the electronic device. Such the induced voltage is generated in a metal case when a charged object of charged hand moves near the metal case. An experiment is conducted where an induced voltage is measured using a real experimental setup when a charged object moves away from the metal case to the left, right, or back. The voltage induced in the metal case is measured using a spark gap and an electromagnetic wave sensor. The results show that the voltages induced in the metal case are -0.6 times the voltage of a charged object when the charged object moves away from the metal case. The induced voltage of 6 kV is generated in the metal case for the charged hand of -10 kV. The results will be beneficial in solving the malfunction or failure of electronic devices caused by induced voltages.

Electrostatically induced voltage generated in ungrounded metal boxes and on a metal box when a charged body moves away from the box

AbstractElectrical discharge and electrostatics are used for the industrial application of a copying machine and electrostatic spraying. However, the electrical discharge and electrostatics occasionally cause malfunction or failure of electronic equipment. When a human body moves in an office, it is electrified up to 10 kV or more. A microelectronic device used in the electronic equipment causes an error owing to the voltage of less than 10 V. When the charged human body moves near the electronic equipment, high induced voltage is generated in the metal box. Comprising electronic equipment, the box is occasionally used at the floating potential of an ungrounded condition. The induced voltage generated for the ungrounded metal box is higher than that generated for the grounded metal box. The results show that the induced voltage generated in an ungrounded metal box is 120% of the inverse polarity against a charged body when the charged body moves away from the box. The induced voltage generated in the ungrounded metal box is higher than that generated on the box. These results would be helpful in designing electronic equipment without malfunctions or failure.

Practical Papers, Articles and Application Notes

With the advancements of robotic technology, robots have been widely deployed in factory automation and health care. One of the major applications of robots in health care is the myoelectric artificial hand. It consists of a myoelectric signal detector connected to a motor-controlled artificial hand driving unit by wires. In the near future, they will be connected wirelessly for convenience but this may pose an EMI risk to the normal operation of the artificial hand. One possible source of EMI is the electrostatic discharge (ESD) from a charged human body. As the malfunction of a myoelectric artificial hand due to ESD has a direct impact on human life, high immunity performance is required. Yasuhiro Morinaga, Keinosuke Nagai, Jianqing Wang and Daisuke Anzai from Nagoya Institute of Technology, Japan, look into this impact and propose design improvements to enhance the immunity of the myoelectric artificial hand against ESD in the paper “Impact of Electrostatic Discharge on Wearable Robotic Hand and Improvement of Immunity Performance by Wireless Control.”

Measurement of electrostatically induced voltages in two metal boxes using spark gaps and electromagnetic wave sensors

Electrostatically induced voltages are generated in metal boxes when a charged human body moves near boxes that have openings. The induced voltages occasionally cause malfunction and failure of electronic equipment. When a human body walks in office that uses air conditioner, the body is electrified. Hence, when a charged body, such as charged human body, moves near metal boxes, high induced voltages are generated in them. In the experiments, two metal boxes similar to the boxes of electronic equipment are used. The induced voltages generated in the two metal boxes are measured. The results will help to resolve electrostatic problem.

Electrostatic induced Voltage and Electrical Discharge generated in Electronic Equipment when charged Human Body moves in Office Building

1．はじめに

Discrimination of Charged Human Body Height and Posture using Electrostatically Induced Voltage

Discrimination of Charged Human Body Height and Posture using Electrostatically Induced Voltage

Experimental consideration of the electrostatically induced voltage generated when a charged body approaches a metal box and moves away from the box

Electrical equipment within a metal box may malfunction due to an electrostatically induced voltage. The voltage of the metal box is induced by the movement of a charged body, such as a charged human body. When the charged body approaches the metal box and moves away from the box, the induced voltage of the metal box generated by the movement of the charged body is experimentally studied in this work. In the experiments, the depth of a metal box is changed, and the result shows that the induced voltage of the metal box when the charged body moves away from the box is approximately −4 times the value of the induced voltage when the body approaches the box in this experimental condition. These results will be useful in designing electrical equipment capable of preventing equipment malfunction and failure.

対向面積の異なる金属筐体から帯電物体を遠ざけたときに生じる静電誘導電圧

A sensitive device, for example, a giant magnetoresistive head contained in an electronic equipment, often malfunctions because of the induced voltage of less than 10V when a charged human body is present near the equipment. Such accidents due to electrostatic induction occur when the charged body moves. The author focuses on the induced voltage of opposite polarity generated on the metal box when the charged body moves away from the box. In experiments, metal boxes of different heights are used to change the facing area between the charged body and the box. In addition, the position of the metal box is changed so that the induced voltages of the box can be compared. The results show that the induced voltages and the electric charges increase as the facing area between the metal box and the charged body increases. The induced voltage of the metal box indicates the value of approximately -370% of the charged body when the facing area between the metal box and the charged body increases. Further, the induced voltages and the charges are slightly dependent of the position of the metal box. The results will be useful for the design of electronic equipment from the standpoint of preventing malfunction and failure of the equipment.

Dependence of Gap Breakdown Field on Charge Voltage in ESD caused by Charged Human-body

Dependence of Gap Breakdown Field on Charge Voltage in ESD caused by Charged Human-body

Dispersive FDTD analysis of induced electric field in human models due to electrostatic discharge

Contact currents flow from/into a charged human body when touching a grounded conductive object. An electrostatic discharge (ESD) or spark may occur just before contact or upon release. The current may stimulate muscles and peripheral nerves. In order to clarify the difference in the induced electric field between different sized human models, the in-situ electric fields were computed in anatomically based models of adults and a child for a contact current in a human body following ESD. A dispersive finite-difference time-domain method was used, in which biological tissue is assumed to obey a four-pole Debye model. From our computational results, the first peak of the discharge current was almost identical across adult and child models. The decay of the induced current in the child was also faster due mainly to its smaller body capacitance compared to the adult models. The induced electric fields in the forefingers were comparable across different models. However, the electric field induced in the arm of the child model was found to be greater than that in the adult models primarily because of its smaller cross-sectional area. The tendency for greater doses in the child has also been reported for power frequency sinusoidal contact current exposures as reported by other investigators.

Electrostatically induced voltage generated in "metal boxes with different volume" measured by spark gap and electromagnetic wave sensor

The movement of a charged body, such as a charged human body or a charged device, often causes a malfunction or failure in an electronic apparatus because an induced voltage is generated in a partially opened metal box of the apparatus. We cannot ignore this type of electronic apparatus malfunction when the relative humidity in a room decreases because of the use of an air conditioner. We need to design the electronic apparatus to safely prevent such malfunctions. The induced voltage generated in the metal box must be measured for the safe design of an electronic apparatus. We measure the induced voltage generated in the metal box without electrical connections using a spark gap and an electromagnetic wave sensor. In this paper, we study the relationship between the induced voltages and the volume of the metal boxes. Five metal boxes with different depths are used to vary the volume of the boxes in the experiment. The measured result shows that the induced voltage generated in the metal box is independent of the volume of the metal boxes (the depth of the boxes). Thus, the value of the induced voltage generated in a small metal box is almost the same as that in a big metal box. Therefore, an induced voltage can be generated in a small metal box, such as a tablet device. The result of this study is useful for the safe design of an electronic apparatus to prevent malfunctions and failure of the apparatus.

ESD currents induced in a charged human body approaching a vehicle

The finite-difference time-domain (FDTD) method is used to calculate electrostatic discharge (ESD) currents induced in a charged human body approaching a vehicle. Maximum current densities induced in the human body are much higher than the threshold current density of 1 μA/cm 2 for the steady-state current flow cases, which may cause biological effects. It is found that the ESD current induced in the heart is smaller than the threshold current required to produce ventricular fibrillation in humans. The specific absorption (SA) induced in the human body is considerably smaller than the value of 28.8 J/kg regulated by the ANSI.

Characteristic measurement of spark transients due to finger touch

To understand a mechanism of spark transients, using a 12-GHz digital oscilloscope, we measured discharge currents due to a finger touch through a hand-held metal bar or a fingertip with an aluminum foil attachment from a charged human body with a charge voltage of 600 V. As a result, we found that the hand-held metal bar and aluminum foil attachment produce a one-shot discharge current with steeply rising time shorter than a 100 ps, while the fingertip without any aluminum foil attachments produces multiple-shot discharge currents with gently rising time larger than a 100 ps and significantly low amplitudes.

Voltage dependence property of parameters for human body discharge in air through a small metal rod

Discharge parameters are measured and calculated in electrostatic discharge (ESD) from charged human body through a small moving handheld metal rod. Correlation study has been performed on discharge parameters with charge voltage as well as approach speed. At charge voltage 800 V, difference of discharge parameters caused by fast and slow approach speed of electrode is found to reach extreme values. To explore the reason for this special case, an analysis with a short-gap ESD model is carried out.

Charging of a person exiting a car seat

Electrostatic charge is generated by the contact, rubbing together and separation of clothing and car seat upholstery. It is also known that the charging levels will increase in a cold and dry climate. Charge on clothing will induce a separation of charge in the body of the wearer. The net result is an increase in the electrical potential of the body (or body voltage), thereby creating the risk of an electrostatic discharge (ESD) in the form of a spark from the charged human body to a large or earthed conductor. As charge is also bound to the surface of the clothing, brush discharges from the clothing can follow. The effects of sparks from the human body in the environment of a car may be a) to cause uncomfortable and distracting shocks to the person; b) to cause damage or disruption to electronic systems (GPS devices, vehicle management systems, etc); or c) to ignite flammable fuel vapour. A brush discharge from clothing may also ignite fuel vapour and be a risk for (unprotected) sensitive electronic devices (ESDS). The characteristic shape of the discharge current in a brush discharge is very similar to a Human Body Model (HBM) discharge. Measurement systems for determining body voltage and recording brush discharges are described. Results are presented of tests conducted with various combinations of car seat upholstery and clothing in different test environments. The antistatic property of some automotive textiles including conductive threads is emphasized.

Wideband measurement of discharge current caused by air discharge through hand‐held metal piece from charged human body

AbstractIn IEC 61000‐4‐2 for electrostatic discharge (ESD) immunity testing, an ESD gun is used to simulate the ESD events from a charged human body. A gun of this kind injects into a device being tested the discharge current through a lumped resistor from a charged lumped capacitor. In actual ESD events from charged human bodies, however, the charge distributed on the body surface is discharged through a spark from the fingertip, and its situation is essentially different from that of the ESD gun. To understand the behavior of the above‐mentioned discharge current, using a 6‐GHz digital oscilloscope, we previously measured the current through a hand‐held metal piece from a charged human body, and proposed an equivalent circuit model for calculating the discharge current with a time‐invariant spark resistance. In this study, with respect to the approaching speed of the hand‐held metal piece, we measured discharge currents through a metal piece from a human body with a charge voltage ranging from 200 V to 1000 V, and estimated the resultant voltage waveforms from the above‐mentioned equivalent circuit model. Through these results, in conjunction with the metal piece speed, we demonstrated the dependence on the charge voltage of current peak, current rise time, time‐varying spark resistance, spark length, and breakdown field. We confirmed also that the spark resistance value at the current peak time enables one to calculate the discharge current, which supports the validity of the previously proposed circuit model. © 2009 Wiley Periodicals, Inc. Electron Comm Jpn, 91(9): 54– 61, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecj.10159

Correlation investigation between contact approach speed of handheld metal rod and discharge parameters from charged human body

Correlation investigation between contact approach speed of handheld metal rod and discharge parameters from charged human body

Correlation investigation between contact approach speed of handheld metal rod and discharge parameters from charged human body

Characteristic measurement of contact discharge currents are made through a hand-held metal rod from charged human body. Correlation coefficients are obtained, through Statistic Package for Social Science (SPSS), for various charge voltages, which is based on the effect test of electrode contact approach speeds on discharge current parameters of current peaks, maximum rising slope and spark lengths. Discharge parameters at charge voltage 300V are independent on approach speed. For charge voltages equal to and higher than 500V, the contact approach speed has strong positive correlation with discharge parameters of the peak current and the maximum rising slope, whereas has strong negative correlation with the spark length.

Investigation of Indirect Electrostatic Discharge (ESD) for a Three-Body Problem

An experimental investigation of indirect electrostatic discharge events for an inline three-body geometry was undertaken. Using conducting cylinders of different sizes to model the test system's conductors, capacitance coefficients were measured, and body potential differences and electric fields were calculated for different geometries of the three floating conductors in close vicinity. The test geometry was chosen to model the approach of the charged human body to an electronic system, which has a neighboring floating conductor; this situation may arise in a manufacturing environment where faulty grounding exists. The parameters studied include body sizes, test geometry, and the relative magnitude and polarity of the charges on the three bodies. An analysis of both first and secondary discharge events is presented and interpreted using a series of charge sensitivity factors. Conditions to support secondary discharges are investigated as a two-body problem

Wideband Measurement of Discharge Current Caused by Air Discharge through Hand-Held Metal Piece from Charged Human-Body

In IEC 61000-4-2 for electrostatic discharge (ESD) immunity testing, an ESD gun is used to simulate the ESD events from a charged human body. A gun of this kind injects into a device being tested the discharge current through a lumped resistor from a charged lumped capacitor. In actual ESD events from charged human bodies, however, the charge distributed on the body surface is discharged through a spark from the fingertip, and its situation is essentially different from that of the ESD gun. To understand the behavior of the above-mentioned discharge current, using a 6-GHz digital oscilloscope, we previously measured the current through a hand-held metal piece from a charged human body, and proposed an equivalent circuit model for calculating the discharge current with a time-invariant spark resistance. In this study, with respect to the approaching speed of the hand-held metal piece, we measured discharge currents through a metal piece from a human body with a charge voltage ranging from 200 V to 1000 V, and estimated the resultant voltage waveforms from the above-mentioned equivalent circuit model. Through these results, in conjunction with the metal piece speed, we demonstrated the dependence on the charge voltage of current peak, current rise time, time-varying spark resistance, spark length, and breakdown field. We confirmed also that the spark resistance value at the current peak time enables one to calculate the discharge current, which supports the validity of the previously proposed circuit model. © 2009 Wiley Periodicals, Inc. Electron Comm Jpn, 91(9): 54– 61, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecj.10159