USRE22421E - Photomechanical negative - Google Patents

Description

Jan. 18, 1944. a. 'RuDNlcK PHOTOMECHANICAIJ NEGATIVE original Fned nay 21. i941 INVENTOR. efgm Rua/mbk BY 7L twwy.

Reissued Jan. 18, 1944 PHOTOMECHANICAL NEGATIVE manier, jHuntington. N. Y., man to Republic Aviation Corporation, Farmingdale,

, N. Y., a corporation o! Delaware Original No. 2,321,046, dated June 8, 1943, Serial No. 418,435, November 10, 1941, which is a division o! Serial No. 394,403, May 21, 1941. Application for reissue ctober z, 1943, Serial No.

505,561 8 Claims.

This invention relates to the preparation of a photo-mechanical negative to be used for the photo mechanical sheets, mechanical layouts, templates, etc.`

The invention aims to provide a photo-me-` chanical negative which can be used in connection with the method of reproduction disclosed in my co-pending application, Serial No. 394,403, filed May 21, 1941, of which the present application is a division.

More particularly the invention aims to provide a negative for reproduction by which inscriptions, for example, line drawings, luminescently produced upon the negative may be transferred to another surface, which has previously been rendered light-sensitive by momentarily placing the two surfaces in contact with each other to cause exposure of the sensitized surface by the luminescent inscriptions.

According to one of the preferred modes of carrying out this method, a stiff backing sheet or plate is coated with a layer of luminescent material having an overcoating of opaque masking material, the layers of luminescent and masking materials constituting what, foriconvenience, I term a negative surface. The copy lsheet to which the design is to be transferred is coated with a film of light-sensitive emulsion so 'as to form what may be referred to as a positive surface. The drawing to be reproduced is made uponthe'negative` surface by means of a stylus or other pointed instrument which cuts or scratches through the overcoating of opaque masking material, and uncovers the luminescent material. After presenting the negative surface to a vbright light, either natural or artificial, to excite the uncovered luminescent material, the treated surfaces are superimposed to allow the light rays emitted by the uncovered luminescent material to act upon the light-sensitive film. Finally the copy sheet is developed and fixed in the usual photographic solutions to reduce the exposed areas to visible metallic silver, leaving these areas black and clear-cut, and corresponding exactly to the lines of the original drawing.

'I'he use of this negative is not limited to this method of reproduction of drawings upon sheet material, and will indeed find great 'utility in machine and sheet metal shop practice inl transferring mechanical layouts or templates as they reproduction of drawingv photo-mechanical negative on which any kind of l line drawings may be readily marked, corrected or completed by means of a stylus sol as to form a master pattern which may be repeatedly used for the preparation of new drawings or the localized correction of old drawings.

Other objects and advantages will be apparent from the following detailed description of two preferred modes of realization of my invention, reference being had to the annexed drawing in which:

Figures 1 to 4 refer to the rst mode;

Figure l is a plan View of a negative or pattern sheet having a drawing inscribed thereon; Figure 2 is a cross-sectional view of the pattern sheet taken on the line 2-2 of Figure 1, the coating layers being shown, 'for greater clearness, somewhat exaggerated in thickness;

Figure 3 `is a cross-sectional view of a copy sheet, which is preferably used in combination l with this negative according to the method of reproduction disclosed in the above-mentioned zzo-pending application, and

Figure 4 indicates the manner in which the negative and this copy sheet are arranged during their exposure.

. Figures 5 and 6 are views similar to Figures 2 and 4 respectively of the second mode; and

Figure 7 shows 'a different manner in which the negative and the copy sheet may be arranged during their exposure.

In Figures 1 and 2 of the drawing is illustrated a photo-mechanical negative or pattern sheet A comprising a backing sheet I, which may be composed of paper, cardboard, metal, or any other suitable material. One surface of the backing sheet is thoroughly cleaned to free it from dirt, grease, or oil, following which a thin coating of white paint 2, containing no lead compounds, is applied over the surface, Upon the coating of white paint is deposited, either by a spray or a brush, a layer of a luminescent composition 3- susper'ided in a transparent vehicle. For this luminescent composition I prefer to use the reaction product resulting from igniting a mixture After allowing the luminescent composition to dry so that it is no longer tacky but firm and hard,

a thin coating of opaque masking material I is evenly distributed over its surface, s o as to completelyl cover the luminescent layer. This mask- `ing material may comprise a black lacquer such as is compatible with the lacquer vehicle containing the luminescent composition. ,l

The layerof luminescent material overlain by 4the coating of masking material constitutes a' negative surface upon which, after drying, a drawing 5 may be inscribed by means of a stylus or other pointed instrument, whichcuts through the overcoating of masking materialy and bares the luminescent composition underneath. Be-

cause of the fact that the masking material adheres as an extremely thin coating to the lumily and clean-cut against the black background of the masking material. 'Should the drattsman make a mistake in initially laying out the drawing, this may be readily corrected by painting over, and thus blacking out the incorrectly placed lines with a black lacquer corresponding in composition to that of the masking material, the correct lines afterwards being added whenA the lacquer has dried.

placed upon a flat, solid support in a dark room,

treated `face up, andthe copy sheet is superimposed iipon the pattern sheet with its treated face heldrmly in engagement with the treated face of thepattern sheet to insure absolute contact therebetween. Under such conditions, the

` light rays emitted by the uncovered luminescent composition act photographically upon the lightsensitive emulsion and cause the silver salts to be y sufliciently aected usually in about one and one-half to two minutes. The thus-exposed copy sheet is finally removedand treated with the usual developing and fixing solutions in a manner which is well-known to the photographic art, and then washed and dried. Because the negative surface retains its luminescence for a considerable time, a great number of copies of the The thus-prepared sheetis now placed in av strong light, which lmay be either naturalsunlight or artificial light, for example, ultra-violet light, the purpose of which is to excite the luminescent composition uncovered by the stylus so that it gives oif radiations in a dark room. Only a few minutes is required for such excitation, following which the pattern sheet is ready 'for use as a master negative from which reproductions of the drawing may be photographically transferred to copy sheets, one of such copy sheets designated B, being shown in cross-section in Figure 3.

The copy sheet B comprises a backing sheet 6 of metal, fabric, paper, glass, synthetic plastic, wood, or any other suitable material, or it may constitute the 'actual work to be operated upon. One face of the backing sheet is cleaned. A coating of priming material 1 is then painted or `sprayed over the cleaned surface, the primer serving both as a filler for closing the pores of the material composing the backing sheet, and as a protective shield between the backing sheet and the emulsion which is subsequently applied thereto, and which otherwise might interact chemically with the backing material. I prefer to use as the primer a suspension of zinc c'hro'-V mate in a carrier selected with consideration to drawing may be reproduced therefrom in a single dark room operation; and when its luminosity becomes spent it can be restored by again presenting it to a strong light.-

The drawing reproduced upon the copy sheet exhibits black, sharply-defined lines against the olive-green background of the primer coating, which is pleasing and restful to the eyes. If desired, however, the olive-green color may be bleached out to reveal the color of the backing sheet 6, by immersing the copy sheet in a dilute solution of ammonium hydroxide; or the copy sheet mayL be rendered transparent if glass or a Y ltransparent plastic is employed as the backing material.

If an aluminum alloy is used as the backing of the copy sheet, the light-sensitive emulsion canbe applied directly on the metal by first clean-- ing the surface in a sodium hydroxide solution a template corresponding to the contour of the the nature of the material composing the backing sheet. When the backing sheet is composed of a metal such as steel, both of its faces, as well as its edges, will be covered ,with the primer to avoid contamination of the chemicals employed in the subsequent developing operation.

`The copy sheet is next placed in a dark room illuminated, for example, by a ruby safelight of the type well known to photography; the temperature is maintained substantially constant and` an emulsion I, consisting for example, of a light-sensitive material, such as silver nitrate suspended in a gelatinous vehicle, is melted and applied as a illm in any suitable manner giving an even thickness, though I prefer to applyit original drawing is obtained. l

Manifestly, the .negative described above is susceptible of modification. While I have found that a luminescent composition incorporating the reaction product of burned calcium carbonate and sulphur, as above-described, gives excellenti results ybesides being comparatively inexpensive toproduce, nevertheless other compositions may be advantageously employed such, for example. as the phosphorus compounds. The coating of white. paint 2 upon the pattern sheet may be omitted if desired, and the luminescent material applied directly to the backing sheet I. However, the ypresence of this white substratum advantageously affects the results obtained, particularly in those cases where the layers of luminescent material is relativelythin, or where the character of the backing material is such as to absorb rather than to reect transmitted light.

vThe pattern sheet may be repeatedly used for the preparation of new or corrected drawings simply by completely or partially blacking over its inscribed surface with a fresh coating of black lacquer. After the lacquer has dried, a new and different drawing, or a localized correction of an old drawing, may be, inscribed upon the renewed surface, the procedure being otherwise the same as that described above.

Another mode of preparing a negative C which can be used to reproduce onto the same light-sensitive coated copy -sheets as are used in the luminous mode may be carried out in the following manner (Figures to 7): a clear plastic sheet .01 to .015 thick is seated with an opaque masking material consisting of two separate layers l0. Il of a metallic lacquer. metallic lacquer are `so applied that they can be scribed off or cut away, without scratching or cutting into the plastic backing sheet 9. The iirst coating I0 is prepared by mixing a quantity of iinely ground aluminum powder in nitro-cellulose lacquer to form a thick paste. This is thinned with a mixture of solvents to a suitable consistency and is applied to the surface of the plastic sheet 9. This coating I0, when dry, renders the plastic material 9 opaque but can readily be removed with a few strokes of a still brush. The material for the second coating Il is prepared by mixing a quantity of metallic powder, which consists mainly of tin, to a greater amount of nitro-cellulose lacquer than Was-used in the iirst coating I0. To this is added enough solvents to thin to the desired consistency and this is applied over the rst layer I0. drying, the second coating II acts as a. binder for ,the rst coating I0. The drawing to be reproduced (not shown) is drawn on this surface by means of a pointed instrument which cuts or removes the top layer Il of masking material These layers of of a luminescent composition supported upon said y backing member. and a coating of an opaque masking material overlying said layer of lumi-y nescent composition, said masking material being of a thickness and composition lsuch as to be readily penetrable by a stylus.

2. Photo-mechanical negative for reproducing designs comprising a backing member, a layer of a luminescent composition supported upon said backing member comprising the reaction product resulting from burning a mixture ,of calcium carbonate and sulphur suspended in a resinous vehicle, and a coating of an opaque masking material overlying said4 layer of luminescent composition; said maskingvmaterial being of a thickness and composition such as to be readily penetrable by a stylus.

3. Photo-mechanical negative for reproducing designs comprising a backing member, a layer of a luminescent composition supported upon said backing member comprising the Lreaction product resulting from burning a mixture of calcium carbonate afnd sulphur together with a relatively small amount of a bismuth salt suspended in a resinous vehicle, and a coating of an opaque masking material overlying said layer of luminescent composition, said masking material being of a thickness and composition such as to be readily penetrable by a stylus.

making it possible to brush out the aluminum powder Il) underneath, covering the transparent plastic backing 9.` This is now used as a photographic negative C. It' is, for instance, placed in. contact with the light-sensitive copy sheet 6, l, 8 and exposed to artificial light for a predetermined time. 'I'hese light rays pass through the transparent portions of the plastic negative C, reacting on the light-sensitive salts of the copy sheet B. The exposed copy sheet B is then processed in the usual photographic solutions. The resulting reproduction appears as a sharply defined black line on a clean contrasting background.

An outstanding advantage in the use of the plastic negative is the fact that leither a right hand or left hand reproduction can be obtained accurately by merely placing the coated surface of the plastic negative C (to produce a copy in reverse of the design as drawn) in direct contact with the light-sensitive copy plate B (as shown in Figure 6) or by placing the back or uncoated surface of the plastic negative in 'contactwith the light-sensitive copy plate (as shown -n Figure '7).

4. Photo-mechanical negativey for reproducing designs comprising a backing member, a layer of a luminescent composition supported upon said backing member comprising the reaction product resulting from burning a mixture of calcium carbonate andsulphur together with a relatively small amount of a manganese salt suspe'nded in a resinous vehicle, and a coating oi an opaque masking material overlying said layer of luminescent composition, said masking material being of a thickness and composition such as to be readily penetrable by a stylus.

5. Photo-mechanical negative for reproducing 'designs comprising a backing. member, a layer of a luminescent composition supported upon said backing member comprising the reaction product'resulting from burning a mixture of calcium carbonate and sulphur suspended in a nitrocellulose lacquer vehicle, and a coating of black lacquer overlying said layer of luminescent composition, said black lacquer being of a thickness such as to be readily penetrable by a stylus.

6. Photo-mechanical negative for reproducing I designscomprising a backing sheet one face of which is thoroughly cleaned, a thin coating. of white paint applied upon this cleaned face, a layer of a luminescent composition suspended in a transparent vehicle spread and dried upon this coating of white paint and a thin coating of an opaque masking material evenly distributed over the surface of this layer of luminescent composition.

7. A photo-mechanical negative for the reproduction of designs comprising a substantially smooth opaque backing member, and a design delineated in an inherently actinic ray emitting material adhered to the backing member.

8. A photo-mechanical negative for the reproduction of designs comprising a substantially smooth opaque backing member, and a design delineated in light-responsive, actinic ray emitting material adhered to the backing member.

BENJAMIN RUDNICK.

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