EP0402338A1 - Verfahren und Gerät zur Neutralisation von elektrostatischen Ladungen bei beweglichen Bahnen - Google Patents

Verfahren und Gerät zur Neutralisation von elektrostatischen Ladungen bei beweglichen Bahnen Download PDF

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Publication number
EP0402338A1
EP0402338A1 EP19900850222 EP90850222A EP0402338A1 EP 0402338 A1 EP0402338 A1 EP 0402338A1 EP 19900850222 EP19900850222 EP 19900850222 EP 90850222 A EP90850222 A EP 90850222A EP 0402338 A1 EP0402338 A1 EP 0402338A1
Authority
EP
European Patent Office
Prior art keywords
brush
web
voltage
neutralising
electrostatic charges
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
EP19900850222
Other languages
English (en)
French (fr)
Inventor
Anders Swahn
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
AKE WIGRENS EL-MEKANISKA AB
Original Assignee
AKE WIGRENS EL-MEKANISKA AB
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by AKE WIGRENS EL-MEKANISKA AB filed Critical AKE WIGRENS EL-MEKANISKA AB
Publication of EP0402338A1 publication Critical patent/EP0402338A1/de
Ceased legal-status Critical Current

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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
    • H05F3/04—Carrying-off electrostatic charges by means of spark gaps or other discharge devices

Definitions

  • the present invention relates to a method for neu­tralising electrostatic charges on a movable web.
  • the invention also relates to an apparatus for carrying out the method, which apparatus comprises a conductive brush disposed adjacent said web, and means for supplying a high-tension alternating voltage to said brush.
  • a web which is coloured with a paint containing metal particles and which risks being unevenly coloured if the web has a vary­ing electrostatic charge.
  • a web which is rolled on a core and which may accumulate such high an electrostatic charge that anyone who touches the roll risks getting heavy electric shocks.
  • Neutralisation can be effected either by means of a passive device, for instance grounded conductor means disposed in the vicinity of the web, or by means of an active device emitting or collecting electrons for neutralising the charges on the web.
  • a passive device for instance grounded conductor means disposed in the vicinity of the web, or by means of an active device emitting or collecting electrons for neutralising the charges on the web.
  • US 4,502,091 describes an active device comprising a bar along which two conductors are arranged. A number of needles have been pressed into each conductor. In opera­tion, a positive high direct voltage is supplied to one conductor and a negative high direct voltage is supplied to the other conductor. By a "point effect", electrons will be collected and emitted, respectively, from the needles for neutralising the charges on the web.
  • US 4,486,808 describes another active device for neutralising random electrostatic charges on a movable web, which simultaneously leaves the web with a uniform, positive, negative or neutral charge.
  • the device comprises a bar spaced from the web and extending transversely thereof. The bar is supplied both with high-voltage direct current and with alternating cur­rent superimposed on the direct current. The frequency of the alternating current is stated to be 600 Hz for both low and high web speeds.
  • the device comprises a con­ductive brush arranged in contact with the web.
  • the object of the present invention thus is to pro­vide a method and an apparatus ensuring satisfactory neu­tralisation of electrostatic charges on the web at both low and high web speeds and for all types of webs.
  • This object is achieved by a method which is charac­terised in that the brush is supplied with an alternating voltage exceeding about 10,000 V and having a frequency exceeding about 1000 Hz.
  • the inventive object is further achieved by means of an apparatus of the type described in the introduction to this specification, which is characterised in that the brush is arranged at a distance from the web and that the means for supplying a high-tension alternating voltage to the brush are adapted to supply the brush with an alter­nating voltage exceeding about 10,000 V and having a fre­quency exceeding about 1000 Hz.
  • the apparatus of the invention can be used also for wet webs and webs which must not be touched.
  • the apparatus further has means adapted to sense the current in the high-voltage circuit of the apparatus and to interrupt the supply to the brush if current above a predetermined limit value is sensed.
  • An apparatus for deionising a web or neutralising static charges on the web comprises, as appears from Fig. 1, a brush 1 arranged transversely of a movable web 2 at a distance of about 10-15 mm therefrom, a voltage transformer 3 and a generator unit 4.
  • the brush 1 is of a known type which is commercially available and which comprises an aluminium section 5 to which a multitude of bristles 6 are attached.
  • the number of bristles may amount to about 3000/cm2.
  • the brush 1 may preferably be a carbon-fibre brush and should be designed in such a manner that the different bristles remain isolated from each other.
  • Each separate bristle 6 forms a tip, and the tips together produce a powerful "point effect" which contributes to improve neu­tralisation.
  • the voltage transformer 3 has a primary winding 7 and a secondary winding 8 which is connected to the brush 1 and coupled in series with a resistor 9, in turn connected to ground.
  • the transformation ratio of the transformer is of the order of 1:1000, and the resistor is of the order of 10 k ⁇ .
  • the point of junction between the secondary winding 8 and the resistor 9 is connected by a line 10 to the generator unit 4. This comprises, in addition to the voltage generator itself, circuits for monitoring ground errors in the high-voltage or secondary circuit.
  • the voltage generator 4 supplies a 12 V alternating voltage of a frequency of 1000 Hz to the transformer 3 stepping up the voltage to 10 kV.
  • this high voltage is applied to the brush, this will emit electrons, by a "point effect", during the negative half period of the alternating voltage. These electrons can then neutralise any positive charges on the web 2 which is travelling past the brush 1.
  • the brush will collect electrons, also by a "point effect”, during the positive half period of the alternating voltage, whereby negative charges on the web are eliminated.
  • Fig. 2 shows a graph illustrating the result of an experiment in which alternating voltage of different mag­nitude and frequency was supplied to the apparatus accord­ing to the present invention.
  • the ordinate represents the potential the web had after deionisation.
  • the potential is the measure of the residual charge on the web.
  • the abscis­sa represents the frequency of the alternating voltage supplied to the brush.
  • the graph contains four curves A-D. Curve A was measured at an alternating voltage equal to 2500 V, curve B at 5000 V, curve C at 10,000 V, and curve D at 14,000 V. The measurements were made at a web speed of 800 m/min.
  • the curves in the graph show that when the frequency is increased from about 50 Hz to about 400 Hz, the deionisation of the web was improved.
  • a further in­crease of the frequency from about 400 Hz to about 800 Hz gives no further improvement of the deionisation.
  • the residual charge on the web decreases slightly at 2500 V and 5000 V, but yet re­mains on a relatively high level.
  • voltages equal to or above 10,000 V and frequencies above 800 Hz a very sub­stantial improvement of the deionisation is however ob­tained.
  • the residual charge is very small, and above 1200 Hz it is so small that it cannot be measured.
  • one or more brushes may also be arranged at the underside of the web.

Landscapes

  • Elimination Of Static Electricity (AREA)
  • Preliminary Treatment Of Fibers (AREA)
EP19900850222 1989-06-05 1990-06-05 Verfahren und Gerät zur Neutralisation von elektrostatischen Ladungen bei beweglichen Bahnen Ceased EP0402338A1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE8902025A SE462412B (sv) 1989-06-05 1989-06-05 Saett att neutralisera elektrostatiska laddningar paa en roerlig bana samt anordning foer utfoerande av saettet
SE8902025 1989-06-05

Publications (1)

Publication Number Publication Date
EP0402338A1 true EP0402338A1 (de) 1990-12-12

Family

ID=20376181

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19900850222 Ceased EP0402338A1 (de) 1989-06-05 1990-06-05 Verfahren und Gerät zur Neutralisation von elektrostatischen Ladungen bei beweglichen Bahnen

Country Status (2)

Country Link
EP (1) EP0402338A1 (de)
SE (1) SE462412B (de)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4224698A1 (de) * 1992-07-25 1994-01-27 Kodak Ag Verfahren zur Messung und kontrollierten Neutralisierung von Oberflächenladungen auf Gegenständen
US5377069A (en) * 1989-04-07 1994-12-27 Andreasson; Tomas Oscillating circuit for the elimination/reduction of static electricity
CN102510651A (zh) * 2011-11-09 2012-06-20 中国乐凯胶片集团公司 一种在薄膜制备中导出薄膜表面静电的方法

Citations (4)

* 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
US4336565A (en) * 1980-08-04 1982-06-22 Xerox Corporation Charge process with a carbon fiber brush electrode
USRE31382E (en) * 1977-03-10 1983-09-13 E. I. Du Pont De Nemours And Company Static charge neutralizer and process
US4486808A (en) * 1982-12-03 1984-12-04 Polaroid Corporation Apparatus for controlling random charges on a moving web

Patent Citations (4)

* 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
USRE31382E (en) * 1977-03-10 1983-09-13 E. I. Du Pont De Nemours And Company Static charge neutralizer and process
US4336565A (en) * 1980-08-04 1982-06-22 Xerox Corporation Charge process with a carbon fiber brush electrode
US4486808A (en) * 1982-12-03 1984-12-04 Polaroid Corporation Apparatus for controlling random charges on a moving web

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5377069A (en) * 1989-04-07 1994-12-27 Andreasson; Tomas Oscillating circuit for the elimination/reduction of static electricity
DE4224698A1 (de) * 1992-07-25 1994-01-27 Kodak Ag Verfahren zur Messung und kontrollierten Neutralisierung von Oberflächenladungen auf Gegenständen
CN102510651A (zh) * 2011-11-09 2012-06-20 中国乐凯胶片集团公司 一种在薄膜制备中导出薄膜表面静电的方法

Also Published As

Publication number Publication date
SE8902025D0 (sv) 1989-06-05
SE462412B (sv) 1990-06-18

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