WO1992020201A1 - Dispositif de decharge d'electricite statique non relie a la terre - Google Patents

Dispositif de decharge d'electricite statique non relie a la terre Download PDF

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Publication number
WO1992020201A1
WO1992020201A1 PCT/US1992/003217 US9203217W WO9220201A1 WO 1992020201 A1 WO1992020201 A1 WO 1992020201A1 US 9203217 W US9203217 W US 9203217W WO 9220201 A1 WO9220201 A1 WO 9220201A1
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WO
WIPO (PCT)
Prior art keywords
conductive
storage capacitor
charge
voltage
air
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/US1992/003217
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English (en)
Inventor
Ezzat G. Bakhoum
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Individual
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Individual
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Filing date
Publication date
Priority claimed from US07/707,691 external-priority patent/US5179497A/en
Application filed by Individual filed Critical Individual
Publication of WO1992020201A1 publication Critical patent/WO1992020201A1/fr
Anticipated expiration legal-status Critical
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Classifications

    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05F—STATIC ELECTRICITY; NATURALLY-OCCURRING ELECTRICITY
    • H05F3/00—Carrying-off electrostatic charges
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05F—STATIC ELECTRICITY; NATURALLY-OCCURRING ELECTRICITY
    • H05F3/00—Carrying-off electrostatic charges
    • H05F3/04—Carrying-off electrostatic charges by means of spark gaps or other discharge devices

Definitions

  • This invention relates to a ground-free device for removing static elec ⁇ trical charge from a conductive or semi-conductive body, and particularly a device of such type which may be mounted on transportation vehicles.
  • While the present invention is broadly useful for removing static electrical charge from conductive and semi-conductive charged bodies, the application of particular concern is the discharge of static electricity from transportation vehicles (cars and aircrafts). Other applications include static discharge from the human body.
  • chains and conductive rods attached to the bodies of these vehicles, have been used to drain static charges by means of friction with the surrounding medium (in the case of automobiles) or by means of Corona discharge (in the case of aircrafts).
  • Corona discharge is also ineffective since a consider ⁇ ably high potential on the body of the aircraft must be reached before the Corona effect is initiated.
  • the Supersonic Nozzle was based on Corona discharge between a pair of oppositely charged electrodes; the Nozzle, in fact, tends to charge the body of the aircraft either positively or negatively (depending on the needle's polarity), even if the body is completely neutral. Such effect is undesirable.
  • the present invention relates to a ground-free device for removing static electrical charge from conductive and semi-conductive bod ⁇ ies, comprising:
  • a storage capacitor comprising first and second terminals
  • a conductive body contact means for establishing electrical contact with the body, and connected to the storage capacitor at a first terminal thereof;
  • a needle electrode for partial static discharge connected to the second terminal of the storage capacitor
  • a Voltage-controlled Oscillator comprising input and output termi ⁇ nals, with the input terminals being connected to the terminals of the storage capacitor;
  • an air ionization mechanism comprising a pre-ionizer and needle dis ⁇ chargers, and featuring first and second terminals, with the first terminal being connected to the body contact means of the device;
  • a circuit for imposing on the air ionization mechanism a voltage which is sufficient for effecting ionization of the air therein but is below the break ⁇ down voltage of the air and featuring input and output terminals, with the input terminals being connected to the output terminals of the Voltage- controlled Oscillator, and with the output terminals being connected to the terminals of the air ionization mechanism.
  • Figure 1 is a schematic representation illustrating the general principle of capacitive removal of charges from a conductive or semi-conductive body, as employed in the present invention.
  • Figure 2 is a schematic representation of a complete device for removal of charges with an efficiency of 95%-100%, according to the pre.sent invention.
  • Figure 3(a) is an end elevation view
  • Figure 3(b) is a corresponding side elevation cross-sectional view, of an air ionization mechanism, comprising a pre-ionizer and needle discharges arranged to inject charges into the stream of ionized air.
  • Figure 4 is a perspective view showing a helicopter-mountable static charge removal device, according to one embodiment of the invention.
  • the present invention is based on the fundamental concept that a con ⁇ ductive or semi-conductive body, such as a human body or a transportation vehicle, can be discharged by touching one side (i.e., plate or terminal) of a capacitor, and that such capacitor may be relatively small in size.
  • This concept although fundamental, has not been previously recognized by those in the field, or applied in any useful device for removing static charges from a body).
  • the body In most instances where friction occurs during bodily movements, the body is charged positively because the human body is more conductive than most other materials (clothing, upholstery, carpet, etc). When the body is travel ⁇ ing in a car, however, the tires can be charged either positively or negatively, depending on the road conditions. For aircrafts, the charge is mostly nega ⁇ tive because air precedes aluminum in the triboelectric series.
  • the potential on the human body is on the order of 20KV volts.
  • the potential can reach 200KV, as mentioned previ ⁇ ously.
  • the amount of charge on the human body and on transportation vehicles is generally small. This is due to the capacitance between the body and the earth being very small. Typically, the capacitance of the human body is 150pF (150 x 10 -12 Farads). A helicopter hovering a few feet above the earth has a capacitance of about lnf (10 ⁇ 9 ) Farads).
  • FIG. 1 illustrates the basic concept underlying the present invention.
  • This figure shows a static charge removal device 100 comprising a capacitor 102 which is connected to a body contact member 104.
  • the body contact mem ⁇ ber in turn is in contact with the body 106.
  • Static discharge occurs as a result of the regenerative induction inside the capacitor: assuming that the body is initially positively charged; few posi ⁇ tive charges from the body create an electric field which ionizes some of the air molecules and attracts several electrons to the negative electrode of the capacitor (as mentioned earlier, this effect is negligibly small at the begin ⁇ ning). Now, by opposite induction, many more positive charges are collected at the positive electrode. The process is self-amplified rapidly, and the air is positively charged.
  • the discharge efficiency of a capacitor was found to be de ⁇ pendent on the strength of the electric field between the body and the earth.
  • the electric field strength depends on the distance between the body and the earth.
  • a discharge efficiency of almost 100% can be reached for isolated bodies (such as the body of an aircraft flying at a high altitude), with a capacitor being mounted on the body, and with the discharge terminal of the capacitor being equipped with a needle electrode (a needle electrode activates the Corona effect, which enhances the discharge efficiency of the ca ⁇ pacitor).
  • bodies relatively close to earth such as human bodies, vehicles, or a hovering helicopter, the discharge efficiency of a capacitor is poor. (Typically, a residual voltage of about 3000 volts on the human body was observed in the experiments).
  • Figure 2 shows a complete device 200 for electrostatic discharge.
  • the device is mountable on a body 202 which is susceptible to static charge build-up, such body may be relatively close to earth.
  • a capacitor 204 serves as an accurate means for estimat ⁇ ing the charge on the body 202.
  • partial discharge occurs by means of the capacitor 204, and through a needle electrode 206 exposed to free air.
  • the voltage build-up across the terminals of capacitor 204 is fed to a Voltage-controlled Oscillator (VCO) 208, such voltage being limited by two Zener diodes 210, as shown.
  • VCO Voltage-controlled Oscillator
  • the output of the VCO triggers a high-voltage generating circuit, comprising two transistors 212 and 214, and a pulse transformer 216.
  • the high-voltage generating circuit is of a known type (a transistor blocking oscillator), being described more fully in Pulse, digital and switching waveforms, by Millman and Taub, McGraw Hill, 1984, page 605.
  • the high-voltage circuit activates an air ionization mech ⁇ anism 218, comprising a hollow cylindrical electrode 220, a solid electrode 222, and needle electrodes 224.
  • FIG.3 A detailed, cross-sectional view of the air ionization mechanism is shown in Fig.3.
  • the principle of operation of the device 200 is as follows: as partial dis ⁇ charge from body 202 occurs through the capacitor 204, a voltage builds up on the capacitor that is proportional to the amount of charge on the body (the capacitor 204 is suitably in the range of O.lnF to O.l ⁇ F).
  • Such voltage difference when fed to the Voltage-controlled Oscillator 208 (or eqivalently, a Voltage-to-Frequency Converter) results in pulses at the output of the os- cillator, the frequency of such pulses being dependent on the input voltage difference, and hence on the amount of static charge on body 202 (the VCO must preferably be capable of generating pulses of a frequency in the range of 0-1 KHz).
  • high voltage pulses are applied to the air ionization mechanism 218, with a frequency being proportional to the amount of static charge on the body 202.
  • the device 200 then, performs the function of ionizing the air to a degree that is proportional to the amount of charge on the body.
  • the air ionization mechanism 218 is the key part of the device 200.
  • the mechanism 218, more fully apparent in Fig. 3, comprises a smooth inner electrode 322 and a hollow cylindrical electrode 320, from which a group of needle electrodes 324 emerge and surround the narrow end of the inner electrode, as shown.
  • the arrangement serves the purpose of overcoming the first deficiency of the Supersonic Nozzle, this deficiency being the requirement for a speed of airflow of about Mach 2.
  • the arrangement practically consists of two different components: the first component, 326, is a "pre-ionizer", which is effectively an air capacitor for performing the function of pre-ionizing the air (in the direction of flow indicated by arrow A in Fig. 3(b) prior to its flow into the second component 328.
  • the component 328 is a "needle discharger" for injecting charges of single polarity into the stream of airflow.
  • the device 200 therefore, can only withdraw a single type of charge from the body 202 (this can be further seen by observing that the Voltage-controlled Oscillator 208 can only respond to an input voltage of single polarity).
  • the body 202 must be equipped with two units of the type shown in Fig. 2; one for positive charge removal and the other for negative charge removal.
  • the pre-ionizer 326 serves the purpose of achieving a high efficiency of discharge at relatively low speeds of airflow; as experiments showed that a high discharge efficiency can be obtained from a needle electrode when air is pre-ionized, thus providing a higher space-charge density at a lower speed of airflow.
  • p is the space-charge density at the outlet of the air capacitor 326 (in Coulombs/m- ⁇ ) and here the flow rate is measured in m ⁇ /sec.
  • the amount of space-charge density inside a uniform-field air capacitor can be simply obtained by applying Gauss' law inside the capacitor, Le.,
  • € 0 is the permittivity of free space
  • E is the electric field intensity
  • d is the width of the air gap inside the capacitor.
  • the space-charge density can be calculated to be about 0.0531 Coulombs/m*- (it should be noted that the breakdown electric field intensity for air is 3000 volts/mm.
  • the device must be operated with a voltage that is below the breakdown point of the air. For example, given an air gap of 0.5 mm, the high voltage circuit must supply a voltage that is less than 1500 volts).
  • the flow rate is equal to the product of the inlet area of the capacitor in Figure 3(b) and the speed of the aircraft. Therefore, with the space-charge density being constant, higher discharge current can be obtained by incre.asing either the inlet area of the air capacitor or the cruising speed of the aircraft.
  • the inlet area given by A ⁇
  • the inside diameter of the outer cylinder 320 should be approximately 0.5 inches, which allows for a compact device to be constructed and mounted on the body of the aircraft.
  • the speed of airflow is the highest at the tips of the main rotor. This location is suitable for mounting the device 200, since the device is very light in weight and very compact in form. Such an arrangement is shown in Fig. 4.
  • a helicopter 402 having a main rotor composed of two blades 404 and 406 carries a device for positive static discharge 408 and a device for negative static discharge 410, such devices being mounted on the rotor tips, as shown.
  • the detailed view of the device 408 shows a housing 410 for the electronic components and the power source of the device, connected to the air ionization mechanism 418 comprising air capacitor and needle dischargers.
  • the devices 408 and 410 are constructed and arranged to be continuously supplied from an independent power source.
  • an independent power source As an example, a typical 500 mAh battery has a lifetime of one year inside such a device. However, operation from the main power source of the vehicle is possible with proper isolation techniques.
  • rotor blades are usually constructed of fiberglass that is cast around a steel member. Since fiberglass is a good insulator, the device must be connected directly to the steel member. Alternatively, the rotor blades can be painted with a layer of conductive paint to establish a connection of low resistance between the device and the helicopter's body. As a still further alternative, the devices 408 and 410 can be mounted on the tail to receive a stream of air from the tail rotor, or elsewhere on the body of the helicopter to be exposed to the downwash of the main rotor.
  • the device of the invention is a ground-free device which requires no connections or couplings to true earth or to large metallic charge-dissipation structures. Further, it will be recognized that the device of the invention may be compactly configured in any of various conformations so as to be body-mountable in character.
  • the device of the invention achieves a high degree of removal of charges from conductive and semi-conductive bodies (and in particular, transported vehicles) at relatively low speeds of airflow.
  • the device depends in its operation on a
  • Voltage-controlled Oscillator which activates the device only when static charge is detected on the body, and in a manner that is proportional to the amount of such charge.
  • One embodiment of the invention which comprises a discharge capacitor equipped with a needle electrode, is particul.arry use for the human body to reduce the static build-up to voltage levels below 3000 volts on the body. Such an application is important for individuals who become in contact with explosive gases or materials, as for example, medical personnel, workers in munition plants, etc.
  • the best mode for carrying out the invention is to construct and ar ⁇ range the device as an independent unit, powered from an independent power source (battery, solar cells, etc.), and mounted outside the body of a vehicle to allow air circulation therethrough.
  • an independent power source battery, solar cells, etc.
  • the body contact means of the device should serve as a mechanical fix ⁇ ture for mounting the device on the body, and, in the same time, as a means for opposite static charges to flow into the body.
  • One embodiment of the invention which comprises a discharge capacitor equipped with a needle electrode, is particularly useful for the human body to reduce the static build-up to voltage levels below 3000 volts on the body. Such an application is important for individuals who become in contact with explosive gases or materials, as for example, medical personnel, workers in munition plants, etc.

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  • Elimination Of Static Electricity (AREA)

Abstract

Dispositif non relié à la terre permettant de décharger l'électricité statique de corps semi-conducteurs ou conducteurs, particulièrement utile pour les véhicules de transport (202), faisant appel à un condensateur (204) pour provoquer et accélérer la décharge dans l'air environnant de l'électricité statique dont un corps est chargé. Le condensateur (204) actionne un oscillateur-traducteur de tension (208) qui permet d'atteindre un taux de décharge de 100 %. L'oscillateur-traducteur de tension (208) détecte la tension du condensateur (204) et produit des impulsions de fréquence à haute tension proportionnelles à la charge du corps. La haute tension ainsi produite provoque la décharge du corps au moyen d'un ioniseur d'air. L'ioniseur d'air (218) est muni d'une électrode (220) placée à l'intérieur d'une chambre et d'au moins une électrode à aiguille (224) placée à proximité de l'extrémité de la chambre. On fait passer un courant à haute tension entre la chambre et l'électrode pour décharger un corps ayant tendance à se chargeren électricité statique.
PCT/US1992/003217 1991-04-25 1992-04-20 Dispositif de decharge d'electricite statique non relie a la terre Ceased WO1992020201A1 (fr)

Applications Claiming Priority (8)

Application Number Priority Date Filing Date Title
US69135091A 1991-04-25 1991-04-25
US691,350 1991-04-25
US07/707,691 US5179497A (en) 1991-04-25 1991-05-30 Ground-free static charge removal device
US707,691 1991-05-30
US82815592A 1992-01-30 1992-01-30
US828,155 1992-01-30
US87006092A 1992-04-17 1992-04-17
US870,060 1992-04-17

Publications (1)

Publication Number Publication Date
WO1992020201A1 true WO1992020201A1 (fr) 1992-11-12

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PCT/US1992/003217 Ceased WO1992020201A1 (fr) 1991-04-25 1992-04-20 Dispositif de decharge d'electricite statique non relie a la terre

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WO (1) WO1992020201A1 (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0695114A4 (fr) * 1994-01-13 1996-02-14
EP0855853A1 (fr) * 1997-01-22 1998-07-29 John H. Hogue Appareil pour perturber et éliminer les électrons et les protons dans l'atmosphère et dans l'espace
WO2002009979A1 (fr) * 2000-07-27 2002-02-07 Giovanni Signorino Dispositif et procede de decharge de charges electrostatiques
EP2299788A3 (fr) * 2009-09-21 2012-10-03 Thomas Mayer Dispositif de déviation de chargements électrostatiques

Citations (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3634726A (en) * 1969-06-03 1972-01-11 Progil Process and device to remove static electricity from plastic films
US4048667A (en) * 1975-08-13 1977-09-13 Hermann Brennecke Device for discharging static electricity
US4107755A (en) * 1977-01-17 1978-08-15 Kiefer Richard J Static eliminator and ion discharge means therefor
US4156267A (en) * 1978-03-06 1979-05-22 Vanguard Energy Systems Gas ionizing
US4180698A (en) * 1976-01-23 1979-12-25 Carpenter Roy B Jr System and equipment for atmospherics conditioning
US4186421A (en) * 1978-05-22 1980-01-29 Kigass Engineering Ltd. Anti-static device
US4271451A (en) * 1976-07-20 1981-06-02 Hercules Incorporated Method and apparatus for controlling static charges
US4333124A (en) * 1976-10-18 1982-06-01 Canon Kabushiki Kaisha Electrically discharging method and device
US4333123A (en) * 1980-03-31 1982-06-01 Consan Pacific Incorporated Antistatic equipment employing positive and negative ion sources
US4498116A (en) * 1980-02-25 1985-02-05 Saurenman Donald G Control of static neutralization employing positive and negative ion distributor
US4523252A (en) * 1982-04-27 1985-06-11 J-O Wallen Electronic Int. Ab Device for eliminating static electricity
US4605984A (en) * 1985-08-05 1986-08-12 Beckman Industrial Corporation Static control strap
US4638398A (en) * 1984-04-04 1987-01-20 Irs Industrie Rationalisierungs-Systeme Gmbh Apparatus for producing positive or negative ions, especially for neutralizing charged workpieces
US4766903A (en) * 1983-07-08 1988-08-30 Herbert Esper Apparatus for detecting of voltages or charges on the human body and for removing such stresses or charges from the human body
US4849851A (en) * 1988-10-31 1989-07-18 American Telephone And Telegraph Company Static electric discharge apparatus with active electrical circuit
US5004425A (en) * 1989-10-10 1991-04-02 Jes, L.P. Magnetic snap assembly for connecting grounding cord to electrically conductive body band

Patent Citations (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3634726A (en) * 1969-06-03 1972-01-11 Progil Process and device to remove static electricity from plastic films
US4048667A (en) * 1975-08-13 1977-09-13 Hermann Brennecke Device for discharging static electricity
US4180698A (en) * 1976-01-23 1979-12-25 Carpenter Roy B Jr System and equipment for atmospherics conditioning
US4271451A (en) * 1976-07-20 1981-06-02 Hercules Incorporated Method and apparatus for controlling static charges
US4333124A (en) * 1976-10-18 1982-06-01 Canon Kabushiki Kaisha Electrically discharging method and device
US4107755A (en) * 1977-01-17 1978-08-15 Kiefer Richard J Static eliminator and ion discharge means therefor
US4156267A (en) * 1978-03-06 1979-05-22 Vanguard Energy Systems Gas ionizing
US4186421A (en) * 1978-05-22 1980-01-29 Kigass Engineering Ltd. Anti-static device
US4498116A (en) * 1980-02-25 1985-02-05 Saurenman Donald G Control of static neutralization employing positive and negative ion distributor
US4333123A (en) * 1980-03-31 1982-06-01 Consan Pacific Incorporated Antistatic equipment employing positive and negative ion sources
US4523252A (en) * 1982-04-27 1985-06-11 J-O Wallen Electronic Int. Ab Device for eliminating static electricity
US4766903A (en) * 1983-07-08 1988-08-30 Herbert Esper Apparatus for detecting of voltages or charges on the human body and for removing such stresses or charges from the human body
US4638398A (en) * 1984-04-04 1987-01-20 Irs Industrie Rationalisierungs-Systeme Gmbh Apparatus for producing positive or negative ions, especially for neutralizing charged workpieces
US4605984A (en) * 1985-08-05 1986-08-12 Beckman Industrial Corporation Static control strap
US4849851A (en) * 1988-10-31 1989-07-18 American Telephone And Telegraph Company Static electric discharge apparatus with active electrical circuit
US5004425A (en) * 1989-10-10 1991-04-02 Jes, L.P. Magnetic snap assembly for connecting grounding cord to electrically conductive body band

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0695114A4 (fr) * 1994-01-13 1996-02-14
US5719739A (en) * 1994-01-13 1998-02-17 Horiguchi; Noboru Static eliminator
EP0855853A1 (fr) * 1997-01-22 1998-07-29 John H. Hogue Appareil pour perturber et éliminer les électrons et les protons dans l'atmosphère et dans l'espace
WO2002009979A1 (fr) * 2000-07-27 2002-02-07 Giovanni Signorino Dispositif et procede de decharge de charges electrostatiques
US7002786B2 (en) 2000-07-27 2006-02-21 Giovanni Signorino Device and method for discharging electric charges
EP2299788A3 (fr) * 2009-09-21 2012-10-03 Thomas Mayer Dispositif de déviation de chargements électrostatiques

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