US3925712A - Multiple copy electrostatic hold-down apparatus - Google Patents

Multiple copy electrostatic hold-down apparatus Download PDF

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Publication number
US3925712A
US3925712A US522352A US52235274A US3925712A US 3925712 A US3925712 A US 3925712A US 522352 A US522352 A US 522352A US 52235274 A US52235274 A US 52235274A US 3925712 A US3925712 A US 3925712A
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US
United States
Prior art keywords
applicator
output
sheets
copyboard
high voltage
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 - Lifetime
Application number
US522352A
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English (en)
Inventor
Harold A Schweriner
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.)
Simco Co Inc
Original Assignee
Simco Co Inc
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 Simco Co Inc filed Critical Simco Co Inc
Priority to US522352A priority Critical patent/US3925712A/en
Priority to GB39342/75A priority patent/GB1484762A/en
Priority to NL7512426.A priority patent/NL163879C/xx
Priority to JP13056175A priority patent/JPS5441505B2/ja
Priority to DE2549189A priority patent/DE2549189C3/de
Priority to FR7533846A priority patent/FR2290688A1/fr
Priority to CH1436475A priority patent/CH605156A5/xx
Priority to SE7512609A priority patent/SE421458B/xx
Application granted granted Critical
Publication of US3925712A publication Critical patent/US3925712A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B27/00—Photographic printing apparatus
    • G03B27/02—Exposure apparatus for contact printing
    • G03B27/14—Details
    • G03B27/18—Maintaining or producing contact pressure between original and light-sensitive material

Definitions

  • a multiple copy electrostatic hold-down apparatus includes a unidirectional high voltage generator having one side, usually at ground potential, connected to a pinning applicator while an automatic switching device periodically and alternately applies first one side and then the other side of the generators D.C. output to the back surface of the copyboard.
  • This invention relates to electrostatic holding apparatus and more particularly relates to an electrostatic copyboardor contact printing apparatus in which a, photosensitive sheet and at least one negative areelectrostatically laminated to the copyboard surface preparatory to exposing the photosensitive sheet to light rays transmitted through each of the negatives.
  • Anotherobject ofthis invention is to provide an electrostatic copyboard in which a photosensitive sheet and at least one'negative may be electrostatically pinned together in laminated disposition preparatory to exposing the photosensitive sheet to light rays transmitted through each of the negatives.
  • the foregoing objectives are achieved by automatically. reversing the DC. output from the unidirectional high voltage generator in its connection to the copyboard wherein there is automatic switching from one side of thepower supply to the other.
  • the switching mode is conducted on a regular periodic basis and rapidly enough so that several intervals of each polarity are applied tothe copyboard during the time it normally takes an operator to.wipe the pinning applicator over a layer of copy held against the copyboards holding surface. In this manner, random areas of positive and negative charge are applied to each layer, such random distributionof the charged areas permitting an adequate overall pinning effect.
  • FIG. 1 is'a perspective view, partly broken away and partly schematic, of a multiple copy hold-down apparatus embodying this invention.
  • FIGS. 2A, 2B and 2C are sectional views demonstrating the'principles of this invention and the charge distribution resulting from the application of the respective layers.
  • an electrostatic copyboard for holding a photosensitive sheet,generally designated as P, and at least one negative sheet, generally designated as N, in electrostatically pinned laminated disposition thereon.
  • a unidirectional high voltage generator B havmine when to perform the switching since the 7 amount of charge developed during any one pinning operation depends on the polarizing and dielectric characteristics not only of the insulative material of the copyboard itself but also of the sheets to be pinned.- For example, some of the layers might not becharged suffiing a D.C. output, an applicator C connected to one side of the high voltage generator and adapted to be .wipedover the outermost surfaces of the photosensi- 3,359,469, 3,448,356, 3,473,097 and 3,549,963.
  • the negative N (or plurality of negatives) would be applied to the top surface of the plate 'A first and the photosensitive sheet P applied last.
  • the lamp or lamps 12 could be located over the copyboard in which case the insulative plate A may be a suitable opaque dielectric, such as a phenolic resin, and the electrode 18 may be a copper plate.
  • the electrode 18 is connected by way of a lead 21 andcurrent limiting resistor 22 to the high voltage power supply B which is capable of applying from about 1,500 to 25,000 volts D.C., positive or negative, to the surface 16 of insulative plate A.
  • the generator B is a conventional unidirectional electrostatic power supply and is shown in block or schematic form in FIG. 1.
  • the instant invention the
  • generator B is illustrated as developing a negative output with respect to ground across resistor 24 when switch 26 located on the control panel is closed.
  • a voltage control transformer 28 also located on the control panel permits the voltage output of the generator to be varied as desired within its range.
  • the applicator C similarly can take a number of forms, and may be a roller, brush or squeegee which is adapted to be moved in contact over the upper surfaces negative D.C. output with respect to ground, a minus voltage will be applied to the electrode 18 during the period the points 32 are closedJWhen the sheet N, or
  • a second sheet N is laid upon the first sheet N in contact with thecopyboard, and the applicator C is drawn over the outer face of the second layer.
  • the second layer N will be charged minus in those areas touched by the applicator during the off or grounded portion of the cycle where the underlying sheet N has a positive charge.
  • the second layer N will be uncharged in those areas touched by the applicator during the of portion of the cycle and in which the underlying sheet N is uncharged.
  • the second layer will be charged plus in those areas touched by the applicator where the underlying sheet N is uncharged but will be uncharged where the underlying sheet N is charged plus.
  • FIG.'2C An example of the charge distribution in three layers is-shown in FIG.'2C wherein a photosensitive sheet P is applied to the laminate of two negatives already pinned to the front surface 20 of the copyboard.
  • the applicator deposits plus charges on the third layer (sheet P) in those areas touched thereby where one of the underlying sheets N is charged plus and the other is charged minus or where neither sheet N is charged but deposits no charge in See for example U.S. Pat. Nos. 3,359,469 or 3,844,657.
  • the essence of the instant invention resides in the automatic switching device D which comprises breaker 1 off the high voltage generator B. It has been found that optimum pinning of plural layers of copy' is accomplished by connecting each mode of the D.C. output for a time interval of about A second to 5 seconds, this being compatible with the speed at which the applicator C is normally drawn over the outer faces of the copy by an operator. In the preferred embodiment of this invention, a period of about 1 second on each mode has been determined to be suitable.
  • the cam 34 is of such a configuration that it closes the breaker points 32 during half of its rotation cycle and opens the points during the other half revolution.
  • the AC is of such a configuration that it closes the breaker points 32 during half of its rotation cycle and opens the points during the other half revolution.
  • synchonous motor 36 running at 30 RPM will cause the cam 36 to close the breaker points 32 for 1 second and maintain them open for 1 second during each-cycle.
  • the copyboard is automatically coupled to ground through current limiting resistor 22 and bleeder resistor 24.
  • the invention functions in the following manner: With the generator B having, a
  • the applicator C deposits minus charges on the third layer P in areas touched thereby where one of the underlying sheets N is charged plus and the other is uncharged but deposits no charge where both underlying sheets N happen'to be uncharged or where one of the underlying sheets is charged plus and the other is charged minus. Accordingly, random plus and minusareas of charge are deposited in the various layers, the applicator C touching randomly different parts of the successive layers during both the on and of portions of the switching cycle.
  • the random charge distribution not only assures that effective electrostatic pinning will occur in multiple sheets, but also produces a lesser degree of shock when the operator touches the sheets directly. Furthermore, the random plus and minus distribution reduces electrostatic sparking between copy layers and/or the copyholding surface as the layers are removed from the copyboard thereby preventing fogging of photosensitive film due to electrostatic sparks.
  • An electrostatic copyboard for holding a plurality of sheets in laminated disposition thereon comprising:
  • a unidirectional high voltage generator having a DC.
  • applicator means adapted for traversal across the outermost face of each of said sheets as such sheet is successively abutted in laminar disposition against one surface of said insulative plate, and
  • automatic switching means for cyclically altering the manner of connecting said high voltage generator to said applicator means and said insulative plate so that during a first portion of the cycle said applicator means and the other surface of said insulative plate are coupled across opposite sides of the DC. output and then during a second portion of the cycle said applicator means and the other surface of said insulative plate are coupled to the same side of the DC. output whereby discrete areas of positive charges and negative charges are randomly dis tributed through the various sheets being laminated.
  • applicator means is connected to the ground side of said D.C. outpu 3.
  • said applicator means comprises a conductive member for contact abutment with said sheets.
  • said automatic switching means comprises a cam-actuated switch.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Exposure Or Original Feeding In Electrophotography (AREA)
  • Electrostatic Charge, Transfer And Separation In Electrography (AREA)
  • Elimination Of Static Electricity (AREA)
  • Electrophotography Configuration And Component (AREA)
  • Dot-Matrix Printers And Others (AREA)
US522352A 1974-11-11 1974-11-11 Multiple copy electrostatic hold-down apparatus Expired - Lifetime US3925712A (en)

Priority Applications (8)

Application Number Priority Date Filing Date Title
US522352A US3925712A (en) 1974-11-11 1974-11-11 Multiple copy electrostatic hold-down apparatus
GB39342/75A GB1484762A (en) 1974-11-11 1975-09-25 Multiple copy electrostatic hold-down apparatus
NL7512426.A NL163879C (nl) 1974-11-11 1975-10-23 Werkwijze voor het hechten van vellen op een elektro- statisch kopieerbord.
JP13056175A JPS5441505B2 (enrdf_load_html_response) 1974-11-11 1975-10-31
DE2549189A DE2549189C3 (de) 1974-11-11 1975-11-03 Kopiertisch zum elektrostatischen Festhalten einer Vielzahl von darauf Übereinander liegenden Blättern
FR7533846A FR2290688A1 (fr) 1974-11-11 1975-11-05 Table electrostatique pour le maintien de feuilles superposees
CH1436475A CH605156A5 (enrdf_load_html_response) 1974-11-11 1975-11-06
SE7512609A SE421458B (sv) 1974-11-11 1975-11-10 Elektrostatiskt kopieringsbord

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US522352A US3925712A (en) 1974-11-11 1974-11-11 Multiple copy electrostatic hold-down apparatus

Publications (1)

Publication Number Publication Date
US3925712A true US3925712A (en) 1975-12-09

Family

ID=24080525

Family Applications (1)

Application Number Title Priority Date Filing Date
US522352A Expired - Lifetime US3925712A (en) 1974-11-11 1974-11-11 Multiple copy electrostatic hold-down apparatus

Country Status (8)

Country Link
US (1) US3925712A (enrdf_load_html_response)
JP (1) JPS5441505B2 (enrdf_load_html_response)
CH (1) CH605156A5 (enrdf_load_html_response)
DE (1) DE2549189C3 (enrdf_load_html_response)
FR (1) FR2290688A1 (enrdf_load_html_response)
GB (1) GB1484762A (enrdf_load_html_response)
NL (1) NL163879C (enrdf_load_html_response)
SE (1) SE421458B (enrdf_load_html_response)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3226280A1 (de) * 1982-07-14 1984-01-19 H. Jürgen Prof. Dr. 4400 Münster Andrä Film-andruck-verfahren

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2025123A (en) * 1931-11-10 1935-12-24 Rahbek Knud Electroadhesion apparatus
US3195363A (en) * 1962-02-09 1965-07-20 Litton Systems Inc Selective driving means
US3359469A (en) * 1964-04-23 1967-12-19 Simco Co Inc Electrostatic pinning method and copyboard
US3480364A (en) * 1967-07-28 1969-11-25 Simco Co Inc The Multilayer electrostatic copyboard and light panel

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2025123A (en) * 1931-11-10 1935-12-24 Rahbek Knud Electroadhesion apparatus
US3195363A (en) * 1962-02-09 1965-07-20 Litton Systems Inc Selective driving means
US3359469A (en) * 1964-04-23 1967-12-19 Simco Co Inc Electrostatic pinning method and copyboard
US3480364A (en) * 1967-07-28 1969-11-25 Simco Co Inc The Multilayer electrostatic copyboard and light panel

Also Published As

Publication number Publication date
DE2549189B2 (de) 1979-08-16
JPS5441505B2 (enrdf_load_html_response) 1979-12-08
FR2290688B1 (enrdf_load_html_response) 1978-05-12
JPS5172340A (enrdf_load_html_response) 1976-06-23
SE7512609L (sv) 1976-07-09
NL163879C (nl) 1980-10-15
FR2290688A1 (fr) 1976-06-04
CH605156A5 (enrdf_load_html_response) 1978-09-29
DE2549189C3 (de) 1980-04-30
DE2549189A1 (de) 1976-05-13
SE421458B (sv) 1981-12-21
GB1484762A (en) 1977-09-08
NL163879B (nl) 1980-05-16
NL7512426A (nl) 1976-05-13

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