US2304838A - Photoengraving - Google Patents

Description

Dec. 15, 1942. RX, 2,304,838

PHOTOENGRAVING Filed Jan. 4, 1940 0- a STHTE I STATE H INVENTOR.

ATTORNEY.

Patented Dec. 15, 1942 2,304,838 rnoroaneaavmc Walter s. Marx, Jr., Park Ridge, 11]., animalto Printing Arts Research laboratories, lnc., Chicago, 111., a corporation oi Delaware Application January 4, 1940, Serial No. 312,348

8 Claims.

This invention relates to photo-engraving, and more particularly to a method of forming highlight negatives for halt-ton printing plates as well as to means for preparing drawings from which such negatives can be produced. This application is a continuation in part or my application Serial No. 209,492, which resulted in Patent No. 2,191,939.

An object of this invention is to provide a simple method of highlighting" that is free from the more lengthy and inexpedient prevailing methods, such as laborious hand-painting or handopaquing, or which involve the employment of special lenses and stops that are in many instances impractical and depend upon delicately balanced exposure relationships, and which in any event are limited to the reproduction of certain types of copy only.

A further object or the invention is to provide a method of, and means for, greatly reducing the cost of highlight half-tone printing plates by decreasing the production time, and substituting for the present diflicult manual method of highcorded, and the second exposure with the halftone screen effectually removed and by means of light changed in frequency by a molecular change in energy levels resulting from theinclusion of predetermined substances in the work areas of the drawing or subject to be photographed, as will hereinafter be disclosed in detail, the non-work or highlight areas remaining unchanged and are thus photographed in said second exposure to the extent required to efiectually cover or efface the' latent-half-tone record or highlight dots of the first exposure without affecting the half-tone pattem'in the work areas.

Th first of the above mentioned exposures is made in the presence of visible or ordinary lightwhilst the second exposure is made in the presence of light rays lying outside of the visible spectrum, that is to say, rays outside the visible spectrum at its violet end, namely, ultra-violet rays, or those rays'which lie just beyond said spectrum at its red end, namely, infra-red rays.

Th order of the two exposures may, of course, be reversed, as will be understood.

A further object of this invention is to improve the accuracy of reproduction of highlight drawings and similar illustrative matter'by the employment of a marking device, such as a pencil.

To this end the present invention also relates to a pencil, the marking material of which includes a substance which will absorb infra-red light or ultra-violet light in such a way that when the markings made by he pencil are photographed by means or such light and with visible or white light in the manner already outlined in connection with the method of this invention above, a highlight halt-tone printing plate may be made photo-automatically from a drawing or subject prepared with such pencil.

The word "pencil is used herein for convenience of description and is therefore to be considered as including in meaning all types of marking devices, such as crayons, pastels, pencil leads, pens, quills, etc., the markings of which may be applied in either liquid or solid phases, or both.

A highlight half-tone printing plate" as herein used is to be understood to mean, asit does in th art, a screened printing plate which is free of dot pattern or other half-tone scanning in the background and/or highlighted areas of the matter so reproduced.

Furthermore, it is to be considered for the purpose of description herein that ultra-violet and infra-red energy forms are actually light waves, and that as such they may be measured, used, and theoretically calculated for conclusions demonstrable from that basis.

Other objects and advantages or the invention will be apparent from the following detailed description by referring to the accompanying drawing, in which: V

Figure 1 is an enlarged section of a marking made-with the pencil of this invention, and

Figures 2 and 3 are structural formulae showing the chemical constitution of markings made with a pencil of this invention, Figure 2 representing para-hydroxybenzaldehyde, and Figure 3 representing anthracene, each compound being typical in general of intra-molecular and intermolecular energy absorption materials respectively, and each figure shows the behavior of these materials during the herein described work thereon, and under the influence of light energy.

According to this invention, the following for- .mula may be used for making up. a pencil, the

markings of which, when made alkaline, will efiectually absorb ultra-violet light:

Extrude under heavy pressure at to degrees C. Dry for fifty hours. 7

After the drawing to be reproduced has been 'marking.

2 asoeass withapencilasabovemadeupitis sprayed or otherwise coated with an alkalising material. A preferred method is to spray the drawing with a volatile alkaiising compound. madeasiollows: Y

Parts by volume Isopropyl alcohol 85 Chemically pure glycerine 10 Morpholine 5 a This spraying compound is preferred became the alkaline material volatilises 01!, leaving the markingsmadehythepencil and supporting-surfacethereoiinamoreneutral andtly more stable condition, sincemost drawing pap oxidise more rapidly in an alkaline state.

Each microscopic particle, or group 01 partltionindicatedbyllandonitsinnerlimitshy theperipheryoftheparticleniseiiectually sorben oi ultra-violet light.

Thus,ifAinFigureiisblack (asintheease of a black pencil) it will absorb both white and intro-violet light; whereas regionf B as defined above will. absorb only in the ultra-violet. Therefore-ii region B is live times the area of regionLtheregipnABwillabsorbsixt-imesmore ultra-violet light than white li t.

The theory upon which the present invention isbasedhingesupon justthat am'plincationof light absorption. The relative numerical. value of absorption quantais, of course, dependent direetlyuponthearearatioofBtoA. Also,the spread of theumbelliierctie solution over B, and determiningthesizeoil3,iseontrolledbythenatureandquantityoithe spray.

Themannerinwhichtheabovelightabsorptionprinciplecanheutilizedssameamicr photo-automatieproduction of highlight halitone printing platesis asfollows:

The drawing or marking of which region AB isapart,isphotographedintwosteps,theiirst step comprising the normal series of half-tone exposures through proper lens diaphragms and half-tone screen, and using white light in the normal manner, thus recording upon the negativeelementahali-tonerecordoithemarking or drawing madewiththe presentpendlzflhe secondstepbeinganauxiliaryexposurcsuperimposeduponthereeordoithefirststep,andmade bymeiinsoif ultra-violet lightonlyandwiththe half-tone screen eiiectually removed Irom the system. Thenlh-a-violet lightreflectediromall regionsaroundABwillrecordcmtinuously over all regions on the ne ative element,-thus veiling over or covering up the heretofore unexposed openings on the negative elemmtwhichweleproiectedthereonbythe halfetone screen in the first step. The screen pattern,ordots,aretherebyeiiectuallyeliminatedinallareasonthe negative element correspondingtothennmarkedoreiieetuallyuntreated areas on the surface supporting the towhite light, and. eiiectuallyab- .oonverscmtheregionanwm havelittleorho appreciable enectonthenegative element during theexposurebyultrawiolet 8 w il area does not eileetually reflectultra-violet light,

butrather absorhsitduetoenergy-transfermce whichmaybeexplainedas follows:

Itmaybecontendedthatalllight absorption istheresultoiinterorintramoleailarenergy absorptiomdirectlyorindirectly. Thisismore mt'rueoftheenergytransierenceinvolved for the purpose or this invention. Therefore, the application of both types of energy absorptionwillbeexplained,andtheuseofany materials alightinsuchmanner,when usediorthesamepurposeandtothesameend asthathereindisclomisconsideredaswithin .thescopeofthisinvmtion.

InFigureLregicnBiscoveredwiththeumbellifemne solution as previously described. 111s residual salt of this umbelliferone solution may be M ;:;-I meturallybyeither anorthoor para quinonoid formula. Since the structural formula for beta-methyi-mnbelliferone is, in this conmction, highly complex, the equivalent and a simpler formula will he givenwith reference to m r p hydehydeas unexample of intra molecularenergy absorption.

Figure 2 shows parai aneutralconditionanditsconflm tioninan alkaline d on, and the t change toaquinonoidstruetme. The phenoliehydrogm isioniriedoii,leavingthenegativeionnivhiiehcan 'existinthetwofonns'shwnMm oneoxygenatomtoanother. Itisthatmobile ehactrcnandthestruchnereslflting from its movement which absorbslight. Or what thephenolicoxygenhokistheelecmasinstate Ltheenergyislowerthanwhm Ingeneralthis electronieactivityismdicaflve oitheacflcnotmanylight-ahsorbing compounds of theintra-molecularmergy absorptiai type," wheretheifreeelectronorelech'omgotromone ormoremergylevelstoanother,suchasquinine sifliate,nuoreaccin,coppersultate,andnearly allrareearthsalmetc.

HSHI'QSanenmpleMintennM 'm in this case anthraccne,

andshowsthebehavioroi' such compounded thesameabsotptiongroupmiforinstanoe,

tmnovertothedi-moleculariormaandas hereimmeismadeol.

thatenergy Someiurther mergy absorling whiehmaybeusedtothesameenmandwhich absorbinsitmsuchasthesaltot mtheintramolecuiar group,orsuchas anthraeeneintheintet molecular group,areqitionaltsd asthisinvmtimbecamethesecompmmdsareper se,-inanenergyabsorhingstate. Also,oompoundswhiehamorbenergythroughdecompositionarewithinthescopeotthismventimastallingwithinflieabove 70 limitsofmolecularenergyabsorptioncharaeteristics. lnbrienanylishtormergy materialormaterials, whenmedto achievethehereinendirrespeetiveol t nmc u eunplcmsreasraum ii-withmthescopeotthepmescutinvmtion.

Grams- This mixture is heated to 180 C. and extruded at high pressure and driedin any manner well known in the art for 50 hours.

Variations of the above formula including in fra-red absorbents other than copper sulfate. may be used to the same end. a

Moreover, sprays or coatings of materials intended to spread-such infra-red absorbent beyond its otherwise normal conflner-(as has been shown in the case of the ultra-violet absorbents)are also required in this case. To spread copper sulfate particles for instance, water and alcohol may be used in equal parts. The spray or coating will,.oi' course, in any case contain an efl'ective quantity of a solvent in which the absorbent used is very highly soluble, and also a detergent capable of spreading the solution so formed, beyond its otherwise normal periphery.

It will be understood that any suitable infrared sensitizing dye is included in the photo-sensitive element used for the photography of inscriptions made by the above marking device aforedescribed and, furthermore, that infra-red light will be substituted for the ultra-violet lightutilized as hereinbefore described in connection with the employment of a marking device containing an absorbent of the latter light.

I claim: I

1. Method of half-tone photography which comprises the steps of making a drawing from which a half-tone printing plate is to be prepared with a marking device, the marking material of which includes a pigment and a substance capable of absorbing light lying outside of the visible spectrum, treating the drawing, with a material adapted to render said substance more eflective' to absorb said light, photographing the drawing so prepared and treated on a light-sensitive element in accordance with the usual halftone procedure and then superimposing on said light-sensitive element a second image of said drawing in the presence of light rays lying outside of the visible spectrum corresponding to those which the drawing has been rendered effective to absorb. I

2. Method of half-tone photography which comprises the steps of making a drawing from which a half-tone printing plate is to be prepared with a marking device, the marking material of which includes a pigment and a substance capable of absorbing light lying outside of the visible spectrum, treating the drawing with a solution adapted to render said substance more eflective to absorb said light and capable of amplifying the area of the drawing over which said absorbent action is eiiective, photographing the drawing so prepared and treated on a lightsensitive element in accordance with the usual Kaolin Benzojc acid 30 Phenanthrene 15 Copper sulfate 20 Gum a nimn 5 Graphite 5 Pigment I 10 and five grams of the following: 7

. Parts White beeswax I 3 Camauba w 5 half-tone vprocedure. and then superimposing 76 on said light-sensitive element a second image -of said drawing in the presence of light rays ,lying outside of the visible spectrum corresponding to those which the drawing has been rendered effective to absorb.

3. Method 01 halt-tone photography which comprises the steps of making a drawing from which a half-tone printing plate is to be prepared with a marking device, the marking material of which includes a pigment and asubstance capable of absorbing ultra-violet light, treating the drawing with a material adapted to render said substance more effective to absorb said light, photographing the drawing so prepared and treated on a light-sensitive element in accordance with the usual half-tone procedure and then superimposing on said lightsensitive element a second image of said drawing in the presence only of ultra-violet light.

4. Method of half-tone photography which comprises the steps of making a drawing from which a half-tone printing plate is to be prepared with a marking device, the marking material of which includes a pigment and a substance capable of absorbing infra-red light, treating the drawing with a material adapted to cause said substance to diilfuse, photographing the drawing so prepared and treated on a light-sensitive element in accordance with the usual halftone procedure and then superimposing on said light-sensitive element a second image of said drawing in the presence only of infra-red light.

5. Method of half-tone photography which comprises the steps of making the drawing from which a halftone printing plate is to be pre-- pared with a marking device, the marking material of which includes a pigment and betamethyl-umbelliferone, applying an alkalizing material to the drawing so prepared, photographing said drawing on a light-sensitive element in accordance with the usual half-tone procedure and then superimposing on said light-sensitive element a second image of said drawing in the presence only of ultra-violet light.

6. A method of half-tone photography for eliminating screen pattern in the highlight portions of a half-tone negative, comprising incorporating in a marking device a pigment and an absorbent of light rays lying outside of the visible spectrum, preparing a drawing to be photographed with the aid of said marking device, photographing said drawing on a lightsensitive element in accordance with the usual half-tone procedure, and then superposing on said element and in register'with the first image, a second image of said drawing in the presence only of light rays lying outside of the visible spectrum corresponding to those which the .drawing'has been rendered efiective to absorb.

7. Method of half-tone photography for eliminating screen pattern in the highlight portions" of a half-tone negative, comprising incorporating in a solid marking device a pigment and an absorbent of light rays lying outside of the visible spectrum, preparing a drawing to be photographed with the aid of said marking device, thereby producing on the drawing shaded portions constituted by a plurality of discrete separate particles of the marking device, treating the drawing with a solvent for said substance whereby some of said substance included within said discrete particles is dissolved and distributed over areas of the drawing around and adjacent said discrete particles, photographing said drawing on a light sensitive element with two separateregisteringexposuregoneofsnidezpcsurm belngeiifectedwiththeaidofascreeninaccordance with usual half-tone procedure, the other ofsaidexposuresbeingmadewiththescreen elfectlmllyremovedandwiththeaironlyotlight rays lying outside of the visible spectrum and corresponding to those which the drawing has been rendered effective to absorb; the lasttioned exposure being made after the solventtreatment of the dralwing.

8. Method of half-tone by for eliminating screen pattern in the highlight portions of a, half-tone negative; comprising incorporating in a solid marking device a pigment'and an absorbent of ultra-violet light rays, preparing a drawing to he photographed with the aidoi said marking f'device, thereby producing on the drawment of the drawing I exposures. oneofsaidbeingeflectedwiththenidofnscreeninaccordancewithusinlhnlt-tone' procedure, the other of said exposures being made with the screen effectually removed and with the aid of ultra-violet light only, the last-mentioned exposure beingmade after the solvent treat 'wnm'za s. MARX. a.

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