EP0055984B1 - Méthode et appareil pour la production de charges relativement élevées sur des matériaux rétenteurs de charges - Google Patents

Méthode et appareil pour la production de charges relativement élevées sur des matériaux rétenteurs de charges Download PDF

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Publication number
EP0055984B1
EP0055984B1 EP82100013A EP82100013A EP0055984B1 EP 0055984 B1 EP0055984 B1 EP 0055984B1 EP 82100013 A EP82100013 A EP 82100013A EP 82100013 A EP82100013 A EP 82100013A EP 0055984 B1 EP0055984 B1 EP 0055984B1
Authority
EP
European Patent Office
Prior art keywords
bristles
reference member
charge
brush
conductive
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.)
Expired
Application number
EP82100013A
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German (de)
English (en)
Other versions
EP0055984A2 (fr
EP0055984A3 (en
Inventor
Semyon Kisler
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.)
Polaroid Corp
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Polaroid Corp
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Filing date
Publication date
Application filed by Polaroid Corp filed Critical Polaroid Corp
Publication of EP0055984A2 publication Critical patent/EP0055984A2/fr
Publication of EP0055984A3 publication Critical patent/EP0055984A3/en
Application granted granted Critical
Publication of EP0055984B1 publication Critical patent/EP0055984B1/fr
Expired legal-status Critical Current

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    • 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 apparatus for establishing a relatively uniform charge level on charge-retaii i ing material, in general, and to such apparatus for establishing a uniform charge level on a moving web of such material, in particular.
  • electrostatic charges on charge-retaining materials causes problems in many industries.
  • electrostatic charges on potential photographs or film units within a light-iight film cassette containing a plurality of film units for use in an "instant" type photographic camera, such as that sold by Polaroid Corporation, Cambridge, Massachusetts, under its registered trademark SX-70 will often cling to one another with such intensity as a result of the force of attraction developed by such electrostatic charges, that proper ejection of an exposed film unit from said film cassette can be prevented if the effects of such charges are not controlled.
  • electrostatic charges are controlled by controlling the charge levels on components said film prior to final film unit assembly.
  • a brush-like device is employed to establish a desired electrostatic charge level on a moving web of charge-retaining material by passing said web through a relatively intense electrostatic field generated by said device when it is electrically connected to a relatively low potential DC source of suitable magnitude and polarity.
  • a similar disclosure of said brush-like device is contained at page 70 in the February, 1980, issue of "Research Disclosure”. This report also shows one embodiment with two brushes spaced in circumferential direction of the roller supporting the web. However, the report is silent about corona effects.
  • US-A-27 74 921 describes an apparatus for electrostatically charging insulating image surfaces for electrophotography comprising a brush means with high-resistance bristles.
  • a limitation of electrostatic charge controlling conductive bristle brush apparatus presently employed to establish an electrostatic charge on charge-retaining material is the inability to place an electrical potential on such a brush that is much in excess of 4.5 KV without generating a corona on said conductive bristle brush. While corona might be acceptable in many charge-retaining material, charge-controlling applications, it is generally unsuitable for use with materials that are sensitive to light such as materials incorporated in many photographic products. In addition, corona produces ozone, and ozone has an odor that may be offensive to personnel in the vicinity of the corona source.
  • FIGs. 1 and 2 a perspective view of prior art charge-controlling apparatus controlling the electrostatic charge on a moving web of charge-retaining material 10 and an equivalent electrical schematic of said apparatus are respectively depicted.
  • a roll of charge-retaining material 10 is moved over rotatably mounted cylindrical rollers 12, 14, 16 and 18 in direction 20 at the desired rate of web 10 movement by suitable drive means (not shown) coupled to said web 10.
  • Brush 22 is mounted in a fixed position and in a spaced relation with respect to web 10 and backing roller 16.
  • the construction of brush 22 will be described below in detail.
  • brush 22 does include a multiplicity of conductive bristles or filaments 24 with an end of each of said filaments being electrically connected to common electrical conductor 26.
  • Backing roller 16 is constructed of electrically conductive materials and said roller 16 is connected to ground potential through path 28.
  • the output of power supply or DC potential source 30 is connected to common electrical conductor 26 through path 32.
  • the input of power supply 30 is connected to a source of electrical energy at terminal 34 (not shown) through path 36. Power supply 30 and grounded backing roller 16 are connected to the same ground potential.
  • electrostatic charges retained by said web 10 are controlled or regulated by said electrostatic field.
  • the magnitude and polarity of the brush potential supplied by potential source 30 is established before web 10 is so moved, by empirically determining the electrostatic field intensity necessary for the desired degree of web 10 electrostatic charge regulation.
  • brush 22 is spaced a finite distance from moving web 10.
  • the magnitude of the potential applied to said brush 22 must be increased in order to obtain the same electrostatic field intensity over a similar arrangement where brush 22 was in actual contact with web 10. This is so because the brush-to- web spacing introduces an electrical impedance or resistance to the generation of an electrostatic field between these components.
  • the electrostatic charge level on web 10 can be properly regulated at lower DC potential when brush 22 is in direct contact with said web 10. However, scratching of the surface of web 10 may occur and such scratching may render portions of web 10 useless for incorporation in an end product.
  • Brushes employed to control the charge level on charge-retaining materials such as web 10 in Figs. 1 and 2 usually have a bristle or filament density in excess of 120,000 filaments per square inch and preferably in excess of 150,000 filaments per square inch.
  • the number of square inches of brush filaments and the physical dimensions of a particular brush are determined by considering such factors as speed of web movement, the initial web charge level and the type of material of which the web is formed. If, as in the charge-controlling arrangement of Figs. 1 and 2, a web such as web 10 is moved over roller 16 at a relatively high rate of speed, it may be necessary to employ two or more commonly connected brushes and space them about the circumference of said roller 16 if a single brush is insufficient to establish the desired web charge level.
  • Brush 22 in Figs. 1 and 2 includes a multiplicity of conductive bristles 24 with each of said bristles having one end connected to common electrical conductor 26, as previously noted.
  • Bristles 24 of said brush 22 are circular in cross-section and are normally constructed of conductive materials such as conductive nylon or stainless steel. Practically any conductive material may be employed for use as bristle material so long as its electrical resistance is 500 megohms or less. Low resistances are not necessary because, unlike a corona-generated field, only a minute amount of current is utilized; primarily for leakage and for dipole orientation.
  • FIG. 4a is an electrical schematic diagram of conductive bristle brush-type electrostatic charge-controlling apparatus that incorporates the sub-corona electrostatic charge level increasing apparatus of the present invention.
  • brush 46 is mounted in a fixed position and in a spaced relation with respect to both web 48 and electrically conductive, rotatably mounted cylindrical backing roller 50.
  • the construction of brush 46 is the same as that of brush 22 described above in Figs. 1 and 2.
  • a brush such as brush 46 in Fig.
  • 4a includes a multiplicity of conductive bristles or filaments 42 with an end of each of said filaments being electrically connected to common electrical conductor 54.
  • Backing roller 50 is constructed of electrically conductive material and said roller 50 is connected to ground potential through path 56.
  • the input of power supply 58 is connected to a source of electrical energy at terminal 60 (not shown) through path 62.
  • Power supply 58 and grounded backing roller 50 are connected to the same ground potential.
  • the output of power supply or DC potential source 58 is connected to current limiting means 64 through path 66 and the output of current limiting means 64 is connected to common electrical conductor 54 of conductive bristle brush 46 through path 68.
  • the electrostatic charge level on web 48 is changed to the desired charge level by the relatively intense electrostatic field established between energized conductive bristle brush 46 and electrically conductive backing roller 50. If the electrostatic charge level sought to be established on, for example, web 48 by brush 46 is larger than a predetermined value, corona will be generated at said brush 46 when the magnitude of the electrical potential on said brush 46 supplied by power supply 58 equals or exceeds said predetermined value.
  • the electrical potential on said brush 46 may be substantially increased above said predetermined electrical potential value without producing corona.
  • corona will be generated at, for example, brush 46 in the electrostatic charge-controlling apparatus of Fig. 4A, is primarily dependent upon the number and size of bristles 52 of brush 46 as well as the magnitude of the potential applied to said brush 46. If the number of bristles in brush 46 is large enough, the desired electrostatic charge level may be obtained before corona develops. However, if corona should develop at a brush potential level necessary to obtain the desired electrostatic charge level on a charge-retaining material, said corona can be suppressed by limiting the available current to a level that is below that necessary to generate and/ or sustain said corona.
  • Current limiting means 64 in Fig. 4a limits the current available to conductive bristle brush 46 from potential or power supply 58 to less than a level necessary for the generation of corona.
  • Current limiting means 64 may take any number of different forms. In Fig. 4b, for example, current limiting means 64 of Fig. 4a takes the form of additional conductive bristles 72 in conductive bristle brush 74. It is useful to consider bristles 52 of conductive bristle brush 46 to be analogous to a multiplicity of resistors, of equal value, that are connected between path 66, that is connected to the high voltage output terminal of power supply 58, and ground path 56 in Fig. 4a. Such an arrangement is represented by resistors 52a, 52b, 52c, etc.
  • Bristles 72 of brush 74 are connected in parallel with bristles 52, which is analogous to adding resistors 72&, 72b, etc. in parallel with resistors 52a, 52b, 52c, etc. in Fig. 4c.
  • bristles 72 resistors 72a, 72b, etc.
  • bristles 52a, 52b, 52c, etc. current from power supply 58 in Fig. 4a that would otherwise flow through bristles 52 and generate corona is shunted through bristles 72 thereby suppressing corona generation.
  • current limiting means 64 in the charge-controlling apparatus of Fig. 4a may take the form of a current-limiting resistor.
  • the ohmic valve of the resistance of said resistor must also be large enough to limit current to a level below that necessary for the generation of corona in order to suppress any corona that would otherwise be produced by, for example, brush 52 in Fig. 4a.
  • the degree to which current through a conductive bristle brush must be limited to preclude the generation of corona is defined by the graph 76 of conductive bristle brush current as a function of brush-to-roller voltage depicted in Fig. 5. As shown in Fig. 5, without additional bristles or a current limiting resistor, corona would begin to develop at brush-to-roller voltage 78 as brush current changed in accordance with graph 80 in said Fig. 5.
  • electrostatic field means one species of electric field.

Landscapes

  • Brushes (AREA)
  • Electrostatic Charge, Transfer And Separation In Electrography (AREA)

Claims (8)

1. Procédé pour la production de charges relativement élevées sur des matériaux réten- teurs de charge (48); comprenant les étapes suivantes:
- faire progresser ledit matériau rétenteur de charge (48) transversalement par rapport à un élément de référence électriquement conducteur (50); installer un dispositif de balai conducteur (46) comprenant une pluralité de poils conducteurs (52) au-dessus dudit élément de référence (50), les extrémités libres desdits poils (52) étant orientées vers ledit élément (50) pour charger ledit matériau rétenteur de charge (48) au fur et à mesure de sa progression entre ledit élément de référence (50) et lesdits poils (52); appliquer aux bornes dudit élément de référence (50) et dudit dispositif de balai (46) un potentiel supérieur à la tension minimale nécessaire pour créer un effet couronne entre ledit dispositif (46) et ledit élément de référence (50); et limiter la circulation du courant entre ledit dispositif de balai (46) et ledit élément de référence (50) à une valeur inférieure à celle qui se produit avec une décharge par effet couronne sous ladite tension minimale de décharge sans limitation du courant.
2. Appareil pour appliquer le procédé de la revendication 1, comprenant:
un conducteur électrique commun (66) et un élément de référence électriquement conducteur (50); un nombre prédéterminé de poils électriquement conducteurs (52) fixés sur ledit élément de référence (50), une extrémité de chacun desdits poils (52) étant en relation électrique de couplage avec ledit conducteur commun (66), lesdits poils (52) s'étendant de leur dite première extrémité en direction dudit élément de référence (50), les extrémités libres desdits poils (52) étant adjacentes audit élément de référence (50); des moyens (64) différents desdits poils électriquement conducteurs (52) pour limiter le courant électrique arrivant sur lesdits poils (52) en provenance d'une source d'alimentation (58) à une valeur inférieure à l'amplitude nécessaire pour établir une décharge par effet couronne entre l'un quelconque d'un nombre prédéterminé de poils électriquement conducteurs (52) et ledit élément de référence (50); ladite source d'alimentation étant une source de tension en courant continu (58) branchée entre ledit conducteur électrique commun (66) et ledit élément de référence (50), le potentiel de ladite source d'alimentation (58) ayant une amplitude et une polarité prédéterminées pour créer un champ électrique qui ajuste la charge électrostatique au niveau de charge désiré sur le matériau rétenteur de charge (48) situé entre lesdites extrémités libres des poils et ledit élément de référence (50), l'amplitude étant telle qu'elle créerait en l'absence desdits moyens limiteurs de courant (64) une décharge par effet couronne entre les poils conducteurs (52) et ledit élément de référence (50).
3. Appareil selon la revendication 2, caractérisé par le fait que lesdits moyens de limitation de courant de l'effet couronne sont constitués par une résistance électrique (72) ayant une valeur ohmique prédéterminée et ladite résistance (72) étant connectée entre ledit conducteur électrique commun (66) et ledit élément de référence électriquement conducteur (50).
4. Appareil selon la revendication 2, caractérisé par le fait que lesdits moyens limiteurs de courant de l'effet couronne sont constitués d'une résistance électrique (64) ayant une valeur ohmique prédéterminée et ladite résistance étant connectée en série entre la source d'alimentation (58) et ledit nombre prédéterminé des poils électriquement conducteurs (52).
5. Appareil selon la revendication 2, caractérisé par le fait que le diamètre de chacun desdits poils conducteurs (52) est égal ou inférieur à 50 pm.
6. Appareil selon la revendication 2, caractérisé par le fait que lesdits poils conducteurs (52) sont en Nylon conducteur.
7. Appareil selon la revendication 2, caractérisé par le fait que lesdits poils conducteurs (52) sont en acier inoxydable.
8. Appareil selon la revendication 3, caractérisé par le fait qu'il comprend un autre dispositif de balai (74) dont les poils (72) sont connectés en parallèle avec les poils (52) du premier dispositif de balai mentionné (46).
EP82100013A 1981-01-05 1982-01-04 Méthode et appareil pour la production de charges relativement élevées sur des matériaux rétenteurs de charges Expired EP0055984B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US22233281A 1981-01-05 1981-01-05
US222332 1981-01-05

Publications (3)

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EP0055984A2 EP0055984A2 (fr) 1982-07-14
EP0055984A3 EP0055984A3 (en) 1982-09-29
EP0055984B1 true EP0055984B1 (fr) 1986-08-06

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EP82100013A Expired EP0055984B1 (fr) 1981-01-05 1982-01-04 Méthode et appareil pour la production de charges relativement élevées sur des matériaux rétenteurs de charges

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EP (1) EP0055984B1 (fr)
JP (1) JPS57164757A (fr)
CA (1) CA1178644A (fr)
DE (1) DE3272402D1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2009127197A3 (fr) * 2008-04-15 2010-03-18 Lindauer Dornier Gesellschaft Mbh Agencement d'électrodes d'immobilisation

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4457256A (en) * 1981-01-05 1984-07-03 Polaroid Corporation Precharged web coating apparatus
US4761709A (en) * 1984-10-29 1988-08-02 Xerox Corporation Contact brush charging
ATE70926T1 (de) * 1987-06-19 1992-01-15 Till Keesmann Vorrichtung zum veraendern des statischen, elektrischen potentials durch koronaentladung an der aus isoliermaterial gebildeten oberflaeche eines bewegten elements.
JPH08315956A (ja) * 1995-05-18 1996-11-29 Kasuga Denki Kk 容器のコロナ放電処理方法及びその装置

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2774921A (en) * 1953-04-23 1956-12-18 Haloid Co Apparatus for electrostatically charging insulating image surfaces for electrophotography
US4213167A (en) * 1978-03-31 1980-07-15 Cumming James M Planar gas and ion distribution

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL292836A (fr) * 1962-05-17
US3308344A (en) * 1965-03-04 1967-03-07 Ener Jet Corp High voltage antistatic apparatus
DE2120397A1 (en) * 1970-04-27 1971-11-18 Progil Removal of static charges from plastic film
US3730753A (en) * 1971-07-30 1973-05-01 Eastman Kodak Co Method for treating a web
JPS5038938B2 (fr) * 1972-01-14 1975-12-13
CH574176A5 (fr) * 1973-11-30 1976-03-31 Gruenenfelder H El Ing Eltex E
JPS5418737A (en) * 1977-07-12 1979-02-13 Sharp Corp Electrophotographic method

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2774921A (en) * 1953-04-23 1956-12-18 Haloid Co Apparatus for electrostatically charging insulating image surfaces for electrophotography
US4213167A (en) * 1978-03-31 1980-07-15 Cumming James M Planar gas and ion distribution

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
EP-A-82100011.4 *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2009127197A3 (fr) * 2008-04-15 2010-03-18 Lindauer Dornier Gesellschaft Mbh Agencement d'électrodes d'immobilisation

Also Published As

Publication number Publication date
EP0055984A2 (fr) 1982-07-14
EP0055984A3 (en) 1982-09-29
JPS57164757A (en) 1982-10-09
CA1178644A (fr) 1984-11-27
DE3272402D1 (en) 1986-09-11

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