US2742833A - Optically sensitized prescreened photographic material - Google Patents

Optically sensitized prescreened photographic material Download PDF

Info

Publication number
US2742833A
US2742833A US234332A US23433251A US2742833A US 2742833 A US2742833 A US 2742833A US 234332 A US234332 A US 234332A US 23433251 A US23433251 A US 23433251A US 2742833 A US2742833 A US 2742833A
Authority
US
United States
Prior art keywords
sensitive
halftone
corners
blue
centers
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
US234332A
Other languages
English (en)
Inventor
Ralph M Evans
Robert E Stauffer
Henry C Yutzy
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.)
Eastman Kodak Co
Original Assignee
Eastman Kodak Co
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
Priority to BE512487D priority Critical patent/BE512487A/xx
Application filed by Eastman Kodak Co filed Critical Eastman Kodak Co
Priority to US234332A priority patent/US2742833A/en
Priority to FR1086266D priority patent/FR1086266A/fr
Priority to GB16362/52A priority patent/GB699340A/en
Application granted granted Critical
Publication of US2742833A publication Critical patent/US2742833A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • 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
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S430/00—Radiation imagery chemistry: process, composition, or product thereof
    • Y10S430/15—Lithographic emulsion

Definitions

  • the sensitive layer in' the present invention is a silver halide emulsion layer usually of the so-called lith type with a gamma greater than four. This permits the making of good quality halftones or combinations of halftonesand line reproductions. gamma between 1.5 and 4 is used to permit either continuous tone or halftone records to be made.
  • Halftone patterns have various forms; the term dot is used to refer to an element of the pattern, the centers being the points of maximum sensitivity or maximum ultimate density and the corners'being the points of minimum sensitivity whatever the shape of the dot.
  • prescreened materials were made by desensitization of the corners. of the dots-in the halftone pattern or by preexposure of the centers of the dots or by both of these steps, or fourthly, by pre-exposing a contact screen in a separate emulsion layer or the opposite side of the primary layer to be developed up with the main image.
  • the present prescreened materials differ from all such former ones in many ways. In .the present materials there is no pre-exposure of the dot centers andno desensitizing of the corners; in fact, the sensitivity of the corners remains substantially unchanged although little harm is done if it inadvertently is increased slightly.
  • the centers are optically sensitized to wavelengths to which the corners are not sensitive.
  • blue sensitive films are used and the added sensitization is for green or red or both, butvthe film may be green sensitive with the added sensitization for red;
  • the variation in spectral sensitivity from the corners to the centers is preferably a continuous one'but may include small areas of constant value right at the center or corner for special effects like drop out highlights or steps of substantially constant value for posterizmg.
  • nal results In fact, a halftone original may be duplicated in this manner. If this same material is exposed to a continuous tone original through a green or yellow filter a halftone image results since the corners of the dots are insensitive to green light or at least havea very much lower sensitivity to green. than the centers have.
  • the difierence in sensitivity from the corners to the centers is, in general, such that the ratio of blue sensitivity to green, or other longer wavelength sensitivityis lessat the centers (which have been optically sensitized to the longer Wavelength) than at the corners (which have received little or no optical sensitization).
  • the sensitizer may be applied from any form of printing plate, letterpress, intaglio or even litho, although sitizer is applied and also on the particular sensitizer used. The rate of drying after printing appears to have.
  • the degree'of diifusionof sensitizer dyes is a ch arac'teristic well known to those working with such. dyes. 'U. S. Patents 2,282,116, Brooker, 2,239,698, Carroll,
  • Figs. 1 to 4 are greatly enlarged cross sections of prescreen films according to different embodiments of the invention.
  • Figs. 5 and 6 illustrate the essential steps in one method of preparing such prescreened films
  • Fig. 7 similarly illustrates an alternative method.
  • a silver halide emulsion layer 10 on a fiat film (or glass) support 11 has a halftone pattern of varying sensitivity distributed over its surface.
  • the point 12 in the emulsion layer 10 constitutes a corner of a dot and is sensitive only to short wavelength light, e. g. blue or blue and green.
  • the point 13 similarly constitutes a center and is sensitive to longer wavelengths e. g. green or red or both when point 12 is blue sensitive only and red when point 12 is green sensitive. Of course, the point 13 is also blue sensitive.
  • Fig. 2 similarly illustrates one of these embodiments in which the emulsion layer has corner points 22 sensitive only to blue (the term blue as used in this specification includes the usual violet and ultraviolet sensitivity common to photographic materials) and center points 23 sensitive to blue and green.
  • the distribution of spectral sensitivity varies continuously from the corners to the centers as graphically represented by the curve 24 although its location in the layer 20 does not necessarily represent an actual boundary between optically sensitized and untreated emulsion. Probably the sensitization extends all the way to the base even near the corners 22 but the number of grains sensitized is greater near the centers 23.
  • the film is any one of the blue sensitive lith types having a high gamma greater than 4 which insures good dot quality, good line reproduction and good halftone quality.
  • Such a film is not intended for continuous tone reproduction but is used either for halftone reproduction or for line reproduction or, by successive exposure through a green or yellow filter for the halftone and through a blue filter for the line, for the combination of both.
  • Fig. 3 illustrates an embodiment of the invention using a lower contrast film such as process film with a gamma between 1.5 and 4 with a halftone pattern with blue sensitive corners 32 and blue and red sensitive centers 33.
  • a blue filter such a film may be used wherever process film is used, e. g. for continuous tone copying, whereas when a red or dark yellow filter is used, this film produces a halftone negative of useful quality which may be contact printed to a lith film or used directly in the making of plates.
  • the dot centers may be either green or red sensitive or sensitive to both.
  • Fig. 4 differs from the other embodiments shown by having two different screen patterns, one 50 lines per inch for newspaper work and the other 120 lines per inch for magazine work.
  • the emulsion 40 is normally a blue sensitive lith type emulsion which has been printed with a 50-line halftone dot pattern of green sensitizer and also with a 120-line halftone dot pattern of red sensitizer.
  • the points 42 are the corners of the 120-line dots and thus have received minimum or no red sensitizer whereas the points 43 are the 120-line centers and have received a maximum of red sensitizer.
  • the two patterns need not be registered in any way but are generally at an angle to avoid any possible moire.
  • the points 45 are the -line corners and have received no green sensitizer although they may or may not be red sensitive.
  • the points 46 are the SO-line centers and have accordingly received the maxirnum amount of green sensitizer. Red and green sensitizers usable in aqueous solution are described below.
  • the film is dried between the printings of the two dyes.
  • a blue sensitive lith type emulsion layer 56 carried on a support 51 is passed between a pressure roll 57 and an intaglio printing roll 52 having small (almost highlight) cavities 53 filled with green sensitizer solution.
  • the relative size of these cavities 53 compared to the area 55 between them is not too critical as long as the cavities are smaller than exact middle tones (checkerboard) but small cavities with a fairly high humidity surrounding the emulsion layer 56 or with a vehicle for the sensitizer which causes it to spread somewhat but not too much through the emulsion, appear preferable.
  • the curve 54 graphically represents the distribution of the sensitizer after printing and drying, for example, by a blower 60 as shown in Fig. 6.
  • a lith type film having a blue sensitive emulsion layer 71 and film base 72 is laid emulsion side up on a flat support or table (not shown).
  • a wash off relief film having a film base 73 and a pattern of raised dots 74 is placed in contact with the emulsion layer 71.
  • This relief pattern of dots is prepared in any of the standard wash off or peroxide etch methods after exposure through a halftone screen. Either sharp small dots (made by exposure in contact with a ruled screen) or rounded dots of the type shown (made by exposure through a graded contact screen or through a ruled screen out of contact) may be used.
  • the relief image is soaked in a bath of sensitizer solution which is thus in the dots 74.
  • a squeegee or roller 75 (with handle 76) is pressed against and across the back of the relief film 73.
  • the sensitizer dye transfers from the dots 74 and is distributed in the emulsion layer 71 according to the shape of the dots 74 and the wandering factor of the dye as discussed above.
  • films according to the present invention have several advantages over prior films.
  • the keeping qualities of optically sensitized emulsions e. g. ortho and pan films
  • the sensitizer Once the films are dry, there is little or no tendency for the sensitizer to Wander under normal storage conditions, so that the halftone pattern has unusual stability and, particularly, stability of scale or range.
  • the range may be selected at will by choice of filter, e. g. a primary green filter in one of the above-mentioned cases gives a maximum scale but a green filter letting through a little blue light compresses the scale accordingly.
  • Optical sensitizers are, of course, well known and the one selected is not critical except with respect to the shape of the resultant dots, i. e. the distribution of sensitivity within each dot. Satisfactory quality prescreening is obtained by printing an ordinary blue sensitive lith film from a copper plate en' graying, lines per inch used as an intaglio plate by flooding with solution of:
  • dye l-carboxymethyl-S-l(3-ethyl-2( l)-benzooxazolylidene)ethylidene]-3-phenyl-2-thiohydantoin 4 cc. triethylamine 96 cc. distilled water and wiping excess solution from the plate with a doctor blade in the usual way.
  • the above dye is a known green sensitizer. Sensitizers in aqueous solutions have a relatively slow drying rate which is an advantage in the present process since faster drying materials have to be printed rapidly to prevent drying out on the printing plate itself.
  • a photographic halftone material comprising a flat support and a photosensitive silver halide emulsion layer on the support with a halftone pattern of square elemental areas juxtaposed with no intervening areas, said square elemental areas having a ratio of green to blue sensitivity greater at the centers than at the corners, and having substantially uniform sensitivity to blue light throughout.
  • a photographic halftone material comprising a flat support and a photosensitive silver halide emulsion layer on the support with a halft-onetpattern of square elemental areas juxtaposed with no intervening areas, said square elemental areas having a ratio of red to blue sensitivity greater at the centers than at the corners, and having substantially uniform sensitivity to blue light throughout.
  • a photographic halftone material comprising a flat support and a photosensitive silver halide emulsion layer on the support with a halftone pattern of square elemental areas juxtaposed with no intervening areas, said square elemental areas having a ratio of blue sensitivity to sensitivity to longer wavelengths less at the centers than at the corners, and having substantially uniform sensitivity to blue light throughout.
  • a photographic halftone material comprising a flat support and a photosensitive silver halide emulsion layer on the support with two halftone patterns of difierent fineness of screen and continuously varying spectral sensitivity across the layer which is substantially uniformly sensitive to blue throughout, has a maximum and minimum sensitivity to green respectively at the centers and corners of the dots of one pattern and a maximum and minimum sensitivity to red respectively at the centers and corners of the dots of the other pattern, each dot pattern being made up of square dots juxtaposed with no intervening areas.
  • a photographic halftone material comprising a flat support and a photosensitive silver halide emulsion layer on the support with a halftone pattern of square elemental areasjuxtaposed'with no intervening areas, said square elemental areas being substantially uniformly sensitive to blue light from the corners to the centers thereof and the centers being more sensitive than the corners to longer wavelength light, thesensitivity tosaid longer wavelength light varying substantially continuously from the centers to the corners.
  • a photographic halftone material comprising a flat support and a photosensitive silver halide emulsion layer on the support with a gamma greater than four and with a halftone pattern of square elemental. areas juxtaposed with no intervening areas, said square elemental areas being substantially'uniformly sensitive to blue light from the corners to'the centers thereof and thecenters being more sensitive than the corners to longer wavelength light, the sensitivity to said longer wavelength light varying substantially continuously from the centers to the corners.
  • a photographic material for continuous tone or halftone reproduction comprising a flat support and a photosensitive silver halide emulsion on'the support with a gamma between 1.5 and 4 and with a halftone pattern of square elemental areas juxtaposed with no intervening areas, said square elemental areasbeing substantiallyuniformly sensitive to blue light from the corners to the' centers thereof and the centers being more sensitive than the corners to longer wavelength light, the sensitivity to said longer wavelength light varying substantially continuously from the centers to the corners.
  • a photographic halftone material comprising a flat support and a photosensitive silver halide emulsion layer on the support with a halftone pattern of square elemental areas juxtaposed with no intervening areas, said square elemental areas being substantially uniformly sensitive to blue light from the corners to the centers thereof and the centers thereof being more sensitive than the corners to green light, the sensitivity to green light varying substantially continuously from the centers to the corners.
  • a photographic halftone material comprising a flat support and a photosensitive silver halide emulsion layer on the support with a halftone pattern of square elemental areas juxtaposed with no intervening areas, said square elemental areas being substantially uniformly sensitive to blue light from the corners to the centersthereof and the centers thereof being more sensitive'than the core ners to red light, the sensitivity to red light varying substantially continuously from the centers to the corners.
  • a photographic halftone material'corn prising a flat' support and a photosensitive silver halide emulsion layer on the support with a halftone pattern of square elemental areas juxtaposed with no intervening areas, said square elemental areas beingsubstantially uniformly sensitive to blue light from the corners to the centers thereof and the centers being more sensitive than the, corners to longer wavelength light, the sensitivity to said longer wavelength light varying substantially continuously from substantial- 1y zero at the corners to a maximum at the centers.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Silver Salt Photography Or Processing Solution Therefor (AREA)
US234332A 1951-06-29 1951-06-29 Optically sensitized prescreened photographic material Expired - Lifetime US2742833A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
BE512487D BE512487A (US07122603-20061017-C00294.png) 1951-06-29
US234332A US2742833A (en) 1951-06-29 1951-06-29 Optically sensitized prescreened photographic material
FR1086266D FR1086266A (fr) 1951-06-29 1952-06-27 Produit photosensible pour la reproduction photomécanique et procédé pour sa préparation
GB16362/52A GB699340A (en) 1951-06-29 1952-06-30 Improvements in photosensitive silver halide emulsions for use in half-tone photographic processes

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US234332A US2742833A (en) 1951-06-29 1951-06-29 Optically sensitized prescreened photographic material

Publications (1)

Publication Number Publication Date
US2742833A true US2742833A (en) 1956-04-24

Family

ID=22880920

Family Applications (1)

Application Number Title Priority Date Filing Date
US234332A Expired - Lifetime US2742833A (en) 1951-06-29 1951-06-29 Optically sensitized prescreened photographic material

Country Status (4)

Country Link
US (1) US2742833A (US07122603-20061017-C00294.png)
BE (1) BE512487A (US07122603-20061017-C00294.png)
FR (1) FR1086266A (US07122603-20061017-C00294.png)
GB (1) GB699340A (US07122603-20061017-C00294.png)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3222986A (en) * 1963-01-04 1965-12-14 Altman Gerald System of optical projection of images by reflex reflected illumination

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US804039A (en) * 1905-07-31 1905-11-07 George N Pifer Photographic plate or film.
US875770A (en) * 1907-03-19 1908-01-07 Benno Borzykowski Pattern-paper linen.
GB250770A (en) * 1925-05-05 1926-04-22 Kodak Ltd Improvements in or relating to the manufacture of photographic films, papers and thelike
US1918208A (en) * 1928-07-28 1933-07-11 Larsen Werner Robert Busch Method of making films for natural color reception
US2009424A (en) * 1931-08-14 1935-07-30 Robert Rochling Color photography
US2061182A (en) * 1933-04-21 1936-11-17 Robert Rochling Method for the production of a photographic exposure material for color screen pictures
US2316643A (en) * 1941-06-06 1943-04-13 Eastman Kodak Co Photomechanical process
US2407211A (en) * 1944-05-26 1946-09-03 Eastman Kodak Co Line and halftone reproduction
FR937885A (fr) * 1945-12-21 1948-08-30 Impression photographique

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US804039A (en) * 1905-07-31 1905-11-07 George N Pifer Photographic plate or film.
US875770A (en) * 1907-03-19 1908-01-07 Benno Borzykowski Pattern-paper linen.
GB250770A (en) * 1925-05-05 1926-04-22 Kodak Ltd Improvements in or relating to the manufacture of photographic films, papers and thelike
US1918208A (en) * 1928-07-28 1933-07-11 Larsen Werner Robert Busch Method of making films for natural color reception
US2009424A (en) * 1931-08-14 1935-07-30 Robert Rochling Color photography
US2061182A (en) * 1933-04-21 1936-11-17 Robert Rochling Method for the production of a photographic exposure material for color screen pictures
US2316643A (en) * 1941-06-06 1943-04-13 Eastman Kodak Co Photomechanical process
US2407211A (en) * 1944-05-26 1946-09-03 Eastman Kodak Co Line and halftone reproduction
FR937885A (fr) * 1945-12-21 1948-08-30 Impression photographique

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3222986A (en) * 1963-01-04 1965-12-14 Altman Gerald System of optical projection of images by reflex reflected illumination
US3269839A (en) * 1963-01-04 1966-08-30 Altman Gerald Photographic product for direct viewing and directive imaging

Also Published As

Publication number Publication date
GB699340A (en) 1953-11-04
FR1086266A (fr) 1955-02-10
BE512487A (US07122603-20061017-C00294.png)

Similar Documents

Publication Publication Date Title
US2304988A (en) Photomechanical reproduction
GB1528836A (en) Photographic colour silver halide materials
US2455849A (en) Photographic unsharp masking method
GB699659A (en) Photographic material for making half-tone records
US2026292A (en) Copying of opaque originals by contact printing
US2742833A (en) Optically sensitized prescreened photographic material
JPH0610751B2 (ja) 写真多色像の色バランスを改良する方法
US2191939A (en) Photoengraving
US2767093A (en) Photo printing process
US3051069A (en) Production of colour prints
US3253918A (en) Print-out element
US2691580A (en) Increasing contrast of halftone reproductions
US2628903A (en) Preparation of printing plates and cylinders with chloro-bromide resist-forming film
US2912325A (en) Light-sensitive film prescreened by herschel exposure
US2102021A (en) Photographic half-tone screen material and process
US2051585A (en) Process of making reflex copies
US2115198A (en) Engraving roller for the manufacture of lenticular film
US2150805A (en) Method of preparing halftone negatives with variable-density screens
US2533650A (en) Process of making half-tone negatives
US2095909A (en) Universal screen for preparing half tones
US3132946A (en) Contact screens for photogravure
US2857273A (en) Photographic film having enhanced herschel effect susceptibility and the process using the same
US3375111A (en) Preparation of printing plates and cylinders with resist-forming film used directly in a camera
US2740323A (en) Color separation apparatus
US2339951A (en) Color photography