US3258341A - Contact screen - Google Patents

Contact screen Download PDF

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Publication number
US3258341A
US3258341A US284491A US28449163A US3258341A US 3258341 A US3258341 A US 3258341A US 284491 A US284491 A US 284491A US 28449163 A US28449163 A US 28449163A US 3258341 A US3258341 A US 3258341A
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United States
Prior art keywords
zones
transparent
opaque
dot
dots
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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
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US284491A
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English (en)
Inventor
Riemerschmid Anton
Eckerlin Wilhelm
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Individual
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Individual
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Publication date
Priority to DEH24216A priority Critical patent/DE958529C/de
Priority to CH345533D priority patent/CH345533A/de
Priority to GB17081/56D priority patent/GB889107A/en
Application filed by Individual filed Critical Individual
Priority to US284491A priority patent/US3258341A/en
Application granted granted Critical
Publication of US3258341A publication Critical patent/US3258341A/en
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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F5/00—Screening processes; Screens therefor
    • G03F5/14—Screening processes; Screens therefor by contact methods
    • G03F5/16—Screening processes; Screens therefor by contact methods using grey half-tone screens

Definitions

  • This invention relates to contact screens.
  • Yet another object of the invention is to provide an improved contact screen wherein all tone ranges of an original are faithfully reproduced with substantially no tone distortion.
  • Still another object of the invention is to provide an improved contact screen which is independent of the density thereof.
  • a still further object of the invention is to provide an improved contact screen which permits a normal preexposure without the occurrence of tone flattening.
  • Yet another object of the invention is to provide an improved contact screen wherein contrasts may be increased or decreased with equal success.
  • the invention contemplates the provision of a contact screen comprising a substantially transparent sheet with a surface layer positioned thereon.
  • the surface layer is provided with perpendicularly disposed linear arrays of evenly spaced substantially opaque dots according to a preferred embodiment. Each group of four adjacent of the dots forms the vertices of a right quadrilateral from which all other of these opaque dots are excluded.
  • the surface layer further includes a gradually varying grey tone portion extending from each opaque dot towards each dot adjacent thereto.
  • Each grey tone portion diminishes to a minimum opacity zone midway between each opaque dot and the corresponding adjacent dot.
  • the minimum opacity zones are in right quadrilateral alignments about respective of the opaque dots, the right quadrilateral alignments constituting the perimeters of varying opacity zones in which the opaque dots are centered.
  • the surface layer is provided with semitransparent zones located at the vertices of the right quadrilateral alignments of the minimum opacity zones, the semi-transparent zones being located in perpendicular linear arrays.
  • the surface layer is further provided with substantially fully transparent dots centrally located in the semi-transparent zones.
  • the semi-transparent zones have about .5 to the opacity of the opaque dots and the minimum opacity zones extend radially from the semi-transparent zones and have no more than about less opacity than the semi-transparent zones.
  • FIGURE 1 is a plan view of a contact screen in accordance with the prior art
  • FIGURE 2 is a plan view of a section of a contact screen provided in accordance with the invention.
  • FIGURE 3 is a pictorial representation of a microphotograph of the contact screen of FIG. 2, with light exposed through the same and rotated 45 relative to the showing of FIG. 2;
  • FIGURE 4 is a view similar to that of FIG. 2, illustrating the dot growth pattern of this screen
  • FIGURE 5 is a view similar to FIG. 1, showing the dot growth pattern of the prior art contact screen
  • FIGURE 6 is an enlarged view of the contact screen of the invention.
  • FIGURE 7 is a further enlarged view of a contact screen of the invention.
  • IISYIGURE 8 is a cross-section along line VIIIVIII of F 7;
  • FIGURE 9 illustrates a dot configuration permissible in accordance with the invention.
  • FIGURE 10 illustrates a further dot configuration permissible in accordance with the invention.
  • FIGURE 1,1 is an enlarged view of a contact screen provided in accordance with the invention, the details thereof being illustrated diagrammatically;
  • FIGURE 12 is a cross-sectional view taken along line XIIXII of FIG. 11;
  • FIGURE 13 is a cross-sectional view taken along line XIII-XIII of FIG. 11;
  • FIGURE 14 is a cross-sectional view taken along line XIVXIV of FIG. 11.
  • Contact screens may be classified according to the arrangement of the dots in the screen. On this basis, two broad groups of screens may be designated, the one based on a checker board arrangement, the other on a so-called in-line arrangement of the invention.
  • each screen dot 20 is separated by an empty space, and that the lines of the dots above and below the given line follow the same order but are offset by one dot. This gives the familiar appearance of the conventional checker board pattern.
  • the contact screens comprising this group are the singlepurpose, offset-only and engraving-only screens.
  • the arrangement of the dots in the screens which follow the in-line pattern is the basis for the second group.
  • This is designated the multi-purpose type and is shown in FIG. 2. It will be noted that on a given line of dots 22 in the screen, the dots are adjacent one another and follow each other in order. The line of dots above and below the given line are identical, and are all in-line, one above the other all the way through. A reproduction of a micro-photograph of the multi-purpose screen is shown in FIG. 3. Some further characteristic features which cannot be reproduced photographically will be four adjacent opaque dots, initial exposure of light passing through this area, results in tiny pin-point dots.
  • FIG. of the drawings a similar dot growth pattern is shown, but the direction of the growth pattern is horizontally and vertically in the screened negative or positive.
  • the multi-purpose screen may cover, for example, a density range of 1.6, i.e., from about .35 to about 1.95.
  • a flash exposure is used for copy having a density range exceeding that of the screen.
  • An interesting characteristic of the multi-purpose screen is indicated in the location of the middle tone values in the halftone when flash exposure is used. This may be illustrated by the following: If a ten step gray scale is photographed through the multi-purpose screen, without flash exposure, a slightly less than 50% dot is observed in the fifth step, and a slightly greater than 50% dot is observed in the sixth step. If normal flash exposures are used, together with the main exposure, this condition still prevails, and the exact middle tones show up essentially as 50% dots in 'the center of the gray scale, where they really belong. Flash exposures with the checkerboard type of screen, however, are observed to shift the 50% dots away from the center of the gray scale.
  • the tone reproduction quality is unaffected by the density of the screen.
  • a lighter screen merely shoots faster. If a process camera or enlarger is used, this feature permits short exposures.
  • the multi-purpose screen is furnished in a medium density which allows fast exposures in the camera, and provides reasonable control if the same screen should be used in a contact frame.
  • this type of screen may be used interchangeably for producing both high contrast offset type negatives, and low contrast engraving type negatives, as desired.
  • the screen is transparent, like the glass crossline screen, it can be used to produce screened negatives from colored copy for black and white production, and for direct, color separation work in the short run process.
  • the density range coverage of the screen is high, approximately 1.6.
  • FIGS. 6 and 7 two enlarged views of a portion of a contact screen such as that illustrated in FIGS. 2 and 4 are shown. To provide for correlation with FIGS. 2 and 4, a dot 22 is indicated.
  • a plurality of substantially opaque dots are employed, preferably in rectilinear arrays which are perpendicularly disposed to one another, the opaque dots being evenly spaced therein.
  • FIG. 6 four opaque dots 24, 26, 28 and are illustrated. These will be considered to constitute a group ofv four adjacent opaque dots which form the verticcs of a right quadrilateral (in this case a square) from which all other of the opaque dots are excluded.
  • opaque dot 24 will be considered to be adjacent opaque dots 26 and 30, but not adjacent opaque dot 28, whereas opaque dot 26 will be considered as being adjacent opaque dots 24 and 28, but not adjacent opaque dot 39, and soon.
  • each opaque dot is surrounded by a gradually varying grey tone portion extending from each opaque dot towards each dot adjacent thereto.
  • each grey tone portion diminishes to a mini-mum opacity zone midway between each opaque dot and the corresponding adjacent dot.
  • minimum opacity zones are arranged in right quadrilateral alignments about respective of said opaque dots.
  • minimum opacity zones 32, 34, and 38 are three sides of a square encompassing the associated opaque dot. It may therefore be said that the right quadrilateral alignments of the-rninimum opacity zones constitute the perimeters of varying opacity zones in which the opaque dot-s are centered.
  • the preferred form of the surface layer to form the zones of varying capacity is that of a multitude of pyramids, the upper vertice of which constitutes the opaque dot. This is shown more graphically in'the cross-sectional view which appears in FIG. 8, wherein the transparent layer 40 may be seen along with the covering or surface layer 42 formed of a material affording suitable opacity in accordance with its thickness.
  • the grey tone is gradually varying rather than a step-by-step variation so that it will be clear that the increments indicated in FIGS. 6 and 7 are for illustration purposes only.
  • the shapes of the opaque dots, as well as the dots 22 may be square, as seen in FIGS. 6 and 7, or polygonal as shown in FIG. 9, or even star-shaped as shown in FIG. 10. Other configurations are also possible within [the scope of the invention.
  • FIG. ll wherein the separate zones and areas contemplated in accordance with the in'vention are illustrated as being sharply delineated from one another. It will be appreciated, however, that in practice the different areas and zones merge into one another rather than having sharp lines of demarcation therebetween. The purpose of showing sharp lines of demarcation between the different zones is to enable a definition of the invention which will facilitate the use thereof by those skilled in the art.
  • a substantially opaque dot 44 is shown, surrounded by four zones 46, 48, 50 and 52.
  • Opaque dot 44 corresponds to the opaque dots 24, 26, 28 and 30 of FIG. 6 and zones 46, 48, 50 and 52 correspond to the dots 22 to which reference has heretofore been made.
  • zones of minimum opacity 53, 54, 56 and 58 are also illustrated, these zones also corresponding to the zones of minimum opacity to which reference has previously been made.
  • zones of minimum opacity which extend radially from respective of zones 46, 48, 50 and 52, cooperatively constitute the perimeter of a varying opacity zone 60, constituted by the above-noted pyramidal variations in the surface layer.
  • zones 46, 48, 50 and 52 are comprised of two separate and distinct parts. Retferring, for example, to the zone 46, it will now appear that this comprises a semi-transparent zone 62, in which is centrally located a substantially fully transparent pinpoint dot or spot 64.
  • surface layer 42 located on transparent sheet 40 has a particular profile to provide for the aforegoing.
  • substantially fully transparent dot appears along section line XII-XII of FIG. 11, as
  • portion 64' in the surface layer 42 which portion represents substantially the absence of the surface layer 42 at this point.
  • the semi-transparent zone appears along section line XIIXII as indicated at 62', the zone of mini-mum opacity appearing between adjacent of the opaque dots appearing in FIG. 12 as shown at 58.
  • the opaque dots, semi-transparent zones and zones of minimum opacity have a preferred physical relationship. More particularly, the semi-transparent zones have about .5 to 5% the opacity of the opaque dots, such as the dot 44.
  • the zones 64' are preferably almost fully transparent.
  • the minimum opacity zones (e.g., zone 58) have no more than about 10% less olpacity than the semi-transparent zones.
  • the opaque spot 44 is shown as being constituted by the peak of the associated pyramid or zone of varying opacity 60. Associated therewith are the semitransparent zones 62" and 62". Also seen in connection with FIG. 13 are the pin point spots of full transparency, such as indicated at 64' and 64". The relationship of the aforenoted pyramids and opaque dots to the associated zones of minimum transparency is apparent from FIG. 14, wherein are illustrated zones 53 and 56 of minimum opacity, located midway between opaque dot 44 and the adjacent of the opaque dots (not shown).
  • the-preferred embodiment of the invention provides that the area of a semi-transparent zoneto the area of a varying opacity zone is in the order of about 1:5 0 to 1:400. More particularly and by way of example,
  • the area of zone 62 to the area of zone 60 is in the range of from about 1:50 to 1:400.
  • a still further characteristic feature of the invention which is believed essential to the practice thereof, involves a particular relationship between the area of the fully transparent dots to the associated semi-transparent zones.
  • the area of fully transparent spot 64 to semi-transparent zone 62 is in the range of from about 1:20 to 1:60.
  • the invention contemplates that the above contact screen is a multipurpose contact screen adapted for use with both offset and letterpress techniques and that reproductions of the highest quality are obtained with such screens with all tone ranges of an original being faithfully reproduced with no tone distortion.
  • contact screens provided with the aforenoted features are independent of the density of the surface layer thereon. Still further, with a normal pre-exposure step, no tone flattening will occur with contact screens of the invention. Still further, contrasts may be increased or decreased with equal success in employing contact screens of the invention. 1
  • a contact screen comprising a substantially trans-.
  • a contact screen comprising a substantially transparent sheet and a surface layer on said sheet, said surface layer having arrays of spaced, substantially opaque dots, each group of four adjacent of said dots forming the vertices of a quadrilateral from which all other of said opaque dots are excluded, said surface layer including a gradually varying grey tone portion extending from each opaque dot towards each dot adjacent thereto, each grey tone portion diminishing to a minimum opacity zone between each opaque dot and the corresponding adjacent dot, the minimum opacity zones constituting the perimeters of varying opacity zones constituted by the varying grey tone portions and in which the opaque dots are centered, said surface layer further having semi-transparent zones located in the minimum opacity zones, said surface layer further having substantially fully transparent spots located in the semi-transparent zones, said semi-transparent zones having about .5 to 5% the opacity of said opaque dots, the areas of said semi-transparent arcashaving a ratio to the areas of said varying opacity zones of about 1:
  • a contact screen comprising a substantially transparent sheet and a surface layer on said sheet, said surface layer having perpendicular linear arrays of evenly spaced, substantially opaque dots, each group of four adjacent of said dots forming the vertices of a right quadrilateral from which all other of said opaque dots are excluded, said surface layer including a gradually varying grey tone portion extending from each opaque dot towards each dot adjacent thereto, each grey tone portion diminishing to a minimum opacity zone midway between each opaque dot and the corresponding adjacent dot, the minimum opacity zones being in right quadrilateral alignments about respective said opaque dots, said right quadrilateral alignments constituting the perimeters of varying opacity zones in which the opaque dots are centered, said surface layer further having semitransparent zones located at the vertices of the rectilinear alignments of said minimum opacity zones, said semitransparent zones being located in perpendicular linear arrays, said surface layer further having substantially fully transparent spots centrally located in the semi-transparent zones, the areas
  • a contact screen comprising a substantially transparent sheet and a surface layer on said sheet, said surface layer having perpendicular linear arrays of evenly spaced, substantially opaque dots, each group of four adjacent of said dots forming the vertices of a right quadrilateral from which all other of said opaque dots are excluded, said surface layer including a gradually varying grey tone portion extending from each opaque dot'towards each dot adjacent thereto, each grey tone portion diminishing to a minimum opacity zone midway between each opaque dot and the corresponding adjacent dot, the minimum opacity zones being in right quadrilateral alignments about respective said opaque dots, said right quadrilateral alignments constituting the perimeters of varying opacity zones in which the opaque dots are centered, said surface layer further having semi-transparent zones located at the vertices of the rectilinear alignments of said minimum opacity zonesfsaid semi-transparent zones being located in perpendicular linear arrays, said surface layer further having substantially fully transparent spots centrally located in the semi-
  • a contact screen comprising .a substantially transparent sheet and a surface layer on said sheet, said surface I layer having perpendicular linear arrays of evenly spaced,
  • substantially opaque dots each group of four adjacent of said dots forming the vertices of a right quadrilateral from which all other of said opaque dots are excluded, said surface layer including a gradually varying grey tone portion extending from each opaque dot towards each dot adjacent thereto, each grey tone portion diminishing to a minimum opacity zone midway between each opaque dot and the corresponding adjacent dot, the minimum opacity zones being in right quadrilateral alignments about respective said opaque dots, said right quadrilateral alignments constituting the perimeters of varying opacity zones in which the opaque dots are centered, said surface layer further having semi-transparent zones located at the vertices of the quadrilateral alignments of said minimum opacity zones, said semi-transparent zones being located in perpendicular linear arrays, said surface layer further having substantially fully transparent spots centrally located in the semi-transparent zones, the areas of said semi-transparent zones having a ratio to the areas of said varying opacity zones of about 1:50 to 1:400, the area
  • a contact screen comprising a substantially transparent sheet and a surface layer on said sheet, said surface layer having perpendicular linear arrays of evenly spaced, substantially opaque dots, each group of four adjacent of said dots forming the vertices of a right quadrilateral from which all other of said opaque dots are excluded, said surface layer including a gradually varying grey tone portion extending from each opaque dot towards each dot adjacent thereto, each grey tone portion diminishing to a minimum opacity zone midway between each opaque dot and the corresponding adjacent dot, the minimum opacity zones being in right quadrilateral alignments about respective said opaque dots, said right quadrilateral alignments constituting the perimeters of varying opacity zones in which the opaque dots are centered, said surface layer further having semi-transparent zones located at the vertices of the quadrilateral alignments of said minimum opacity zones, said semitransparent zones being located in perpendicular linear arrays, said surface layer further having substantially fully transparent spots centrally located in the semitransparent zones, said semi-
  • a contact screen adapted for use with letterpress and offset printing techniques comprising a substantially transparent sheet and a surface layer on said sheet, said surface layer having perpendicular linear arrays of evenly spaced, substantially opaque dots, each group of four adjacent of said dots forming the vertices of a right quadrilateral from which all other of said opaque dots are excluded, said surface layer including a gradually varying grey tone portion extending from each opaque dot towards each dot adjacent thereto, each grey tone portion diminishing to a minimum opacity zone midway between each opaque dot and the corresponding adjacent dot, the minimum opacity zones being in right quadrilateral alignments about respective said opaque dots, said right quadrilateral alignments constituting the perimete'rs of varying opacity zones in' which the opaque dots are centered, said surface layer further having semi-transparent zones located at the vertices of the quadrilateral alignments of said minimum opacity zones, said semitransparent zones being located in perpendicular linear arrays, said surface layer further having
  • a screen as claimed in claim 7 wherein said sheet is a rig-ht quadrilateral and the linear arrays are arranged at 45 to the sides of the sheet.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Facsimile Image Signal Circuits (AREA)
  • Printing Methods (AREA)
  • Non-Silver Salt Photosensitive Materials And Non-Silver Salt Photography (AREA)
US284491A 1955-06-23 1963-05-31 Contact screen Expired - Lifetime US3258341A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
DEH24216A DE958529C (de) 1955-06-23 1955-06-23 Kontakt-Raster
CH345533D CH345533A (de) 1955-06-23 1956-06-19 Kontaktraster
GB17081/56D GB889107A (en) 1955-06-23 1958-02-17 Improvements in or relating to contact screens for use in graphic reproduction
US284491A US3258341A (en) 1955-06-23 1963-05-31 Contact screen

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DEH24216A DE958529C (de) 1955-06-23 1955-06-23 Kontakt-Raster
US284491A US3258341A (en) 1955-06-23 1963-05-31 Contact screen

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US3258341A true US3258341A (en) 1966-06-28

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US284491A Expired - Lifetime US3258341A (en) 1955-06-23 1963-05-31 Contact screen

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CH (1) CH345533A (de)
DE (1) DE958529C (de)
GB (1) GB889107A (de)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4114982A (en) * 1976-04-15 1978-09-19 Raymond Buckley Screens suitable for use in photo-engraving and photo-lithographic processes and in color television
DE3302061A1 (de) * 1982-05-28 1983-12-01 Grafobal, N.P., Skalica Kombiniertes kontakt-autotypieraster
US4834502A (en) * 1988-08-08 1989-05-30 Xerox Corporation Optical mouse pad

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE635095A (de) * 1962-07-17
US4600666A (en) * 1983-01-12 1986-07-15 Zink Edmund S Integrated photoscreen for making a halftone reproduction printing plate from a photograph
DE3376766D1 (en) * 1983-12-29 1988-06-30 Agfa Gevaert Nv Photographic method for the production of documents

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US401510A (en) * 1889-04-16 Carl august muller
US1896567A (en) * 1926-11-04 1933-02-07 Pantone Corp Screen for photographic purposes, photomechanical printing processes and the like
US1995958A (en) * 1933-03-03 1935-03-26 Photo Cast Inc Universal screen for preparing half-tones
US2292313A (en) * 1940-04-19 1942-08-04 Eastman Kodak Co Halftone screen

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE145399C (de) *
DE147523C (de) *
DE293218C (de) * 1915-01-05
US1407029A (en) * 1920-10-14 1922-02-21 Hatt Joseph Arthur Henry Photoprocess screen and method of preparing same
DE884604C (de) * 1951-04-23 1953-06-11 Heinrich Heichlinger Tiefdruck-Raster

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US401510A (en) * 1889-04-16 Carl august muller
US1896567A (en) * 1926-11-04 1933-02-07 Pantone Corp Screen for photographic purposes, photomechanical printing processes and the like
US1995958A (en) * 1933-03-03 1935-03-26 Photo Cast Inc Universal screen for preparing half-tones
US2292313A (en) * 1940-04-19 1942-08-04 Eastman Kodak Co Halftone screen

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4114982A (en) * 1976-04-15 1978-09-19 Raymond Buckley Screens suitable for use in photo-engraving and photo-lithographic processes and in color television
DE3302061A1 (de) * 1982-05-28 1983-12-01 Grafobal, N.P., Skalica Kombiniertes kontakt-autotypieraster
US4834502A (en) * 1988-08-08 1989-05-30 Xerox Corporation Optical mouse pad

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Publication number Publication date
DE958529C (de) 1957-02-21
GB889107A (en) 1962-02-07
CH345533A (de) 1960-03-31

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