US1482615A

US1482615A - Process of photographic reproduction directly from a negative

Info

Publication number: US1482615A
Application number: US327890A
Authority: US
Inventors: John Robert
Original assignee: DAYLIGHT FILM CORP
Current assignee: DAYLIGHT FILM Corp
Priority date: 1919-10-02
Filing date: 1919-10-02
Publication date: 1924-02-05
Anticipated expiration: 1941-02-05

Description

Patented Feb. 5, 1924.

f UNITED STATES tame ROBERT JOHN, OF NEW YORK, N. Y., ASSIGNOR T DAYLIGHT FILM CORPORATION, A CORPORATION OF NEW YORK.

PROCESS OF PHOTOGRAPHIC REPRODUCTION DIRECTLY FROM A NEGATIVE.

No Drawing.

- duction Directly from a Negative, of which the following is a specification.

" My invention relates to a process of photo graphic reproduction directly, from a negative and has for its object to produce a printingsurface containing a photographic record'of lights and shades from which copies can be made b' a dye or ink contact transfer process. in illustrative dye contact transfer'process is disclosed in patent to Shepherd and Bartlett, No. 7 28,310, granted May 19, 1903,for photographic printing, and an illustrative ink contact transfer proc- 2o ess is disclosed in (Jassells Cyclopaedia of Photography, Gassell & (10., New York, 1912, at page 124 under the title Collotype, it being understood, however, that t e processes thus illustrated, do' not use a 2 printing plate having the novel and beneficial characteristics of the printingplate disclosed herein. Although for general purposes the preferred method is to obtain the photographic record for the printing surface from a completed negative, it may be obtained by direct exposure, as, for example, in a camera, as described herein. The printing surface when treated with dye or ink also may be used in the same manner as a positive, either for direct view, or with refiected light, or with transmitted light as in a projecting machine.

The invention is applicable to monochromatic, polychromatic, or natural color photography both in still photography and in motion picture photography. he term color isintended toincl de black, which sometimes technically is designated as an .absence of color.

In the embodiment of my invention chosen for purposes of illustration, a sensitized.

emulsion such as a silver salt emulsion is ex- 7 posed,as, for example, in a camera, to the action of light modified by the lights and shades of the object which itis desired to reproduce. The silver salt emulsion may-be carried or mounted on any deslred support, either opa ue, translucent, or transparent, but prefera 1y is mounted on a transparent ing surface having novel Application filed October 2, 1919. Serial No. 327,890.

carrier such, for example, as glass or a cellulose base, in order that the silver salt emulsion may be exposed to the-modified light through its transparent carrier.

The exposed emulsion then is-treated by any ordinary developer having no tanning orhardening action on the emulsion, after which it is rinsed thoroughly in cold water and exposed again, preferably through its transparent carrier, to an actinic light. At this stage, therefore, the unhardened emulsion has two images-one the usual photographic reversed negative image in metallic silver. and the other a latent image in undeveloped, lightsafl'ected, sensitized particles correctly reproducing I the object photographed the same as would a positive made in usual manner from a negative. It then is necessary only'to harden the emulsion adjacent the undeveloped, light-affected, sensitized particles and remove the unhardened emulsion in order to obtain the desired printing surface on the original negative.

()ne process of hardening the emulsion adj acent the undeveloped, light-alfected, sensitized particles is described in my copending application for Letters Patent Serial No. 313.237, filed July 25, 1919, which eventuated into Patent No. 1,374,853, granted April 12, 1921. In the embodiment of that process described in said application, the emulsion is treated by a developing solution containing a hardening or tanning agentwhich renders insoluble or unremovable the emulsion adjacent its light-affected, lightsensitive content, the effect of which agent is controlled or limited selectively by the presence of varying quantities of a neutralizing agent, after which the soluble or removable portions of emulsion are removed in any desired manner, as, for example, by melting with warm water. y g

The result of he above treatment isthe production of what may be termed a. printcharacteristics and beneficial properties never before attained.

The most important of thenovel characteristics is a printing surface comprising granules or. great numbers of photographcally formed, extremely minute, individual rotuberances which are distributed and grouped irregularly so as to represent photo aphic lights and shades.

most lmportant of the beneficial properties is that such a printing surface when treated with a dye, ink, or other coloring matter, will absorb or take up or carry the coloring matter within a few seconds, and when thus treated and placed in contact with a substance which is to carry the final reproduction, such for example as a gelatin, will give up its coloring matter practically instantaneously and produce on said gelatin an exact and perfect reproduction. This speedy result, which is novel and was impossible of attainment before the present invention, is of prime importance in the production of motion picture ositives from motion picture negatives, alt ough the saving of time and thesuperior'results obtainable in still photographv also are important. The printing plate or lm, moreover, when treated with coloring matter, may be used as a positive if reproductions are not desired.

A sample formula for a developing solution containing a hardening or tanning agent the effect of which is controlled and limited selectively by the resence of varyin quantities of a neutra izingagcnt is as fo lows: I

Water 8.5 ounces.

In the'above sample formula the hardening or tanning agent phite which may be varied in amount selectively within limits to obtain the desired result. It. is well known acid also is a developing agent and that sodium sul bite is a preservative adapted to prevent oxidation of the pyrogallic acid in solution. Other hardening and tanning agents and other neutralizing agents may be used, the above formula representing one developing solution by which the process may be carried out. Potassium bromide, for example, also has a certain controlling and limiting effect. The main difference between the above sample formula and standard developing formulas is in the amount of sodium sulphite used. In stand ard formulas the amount of sodium sulphite used is so greatly in excess of the amount used in the above sample formula that the tanning or hardening effect of the pyrogallic acid is entirel neutralized or overcome. In the sample ormula, the sodium sulphite merely controls and efl'ect of the p rogallol. It is of course understood by t ose skilled in the art that when a thick layer of emulsion is treated, or when the exposure is through the transis pyrogallic acid, and the. controlling and limiting agent is sodium sulthat pyrogalli x.

limits the hardening be parent carrier, it is advisable, in order to accelerate the action of the pyrogallic acid, to use larger quantities of an accelerator such, for example, as sodium carbonate or its equivalents than when the emulsion layer is thin or exposed on its face. When larger quantities of sodium carbonate thus are used, it is necessary to increase the amount of sodium sulphite. The above sampleformula is for treatment of an emulsion exposed through its transparent carrier and therefore contains a comparatively large amount of sodium carbonate with an increased amount of sodium sulphite. In order to obtain the desired printing surface, however, the amount of sodium sulphite in the process disclosed herein is much less than would be used ina developing solutionfor the usual development of the particular emulsion layer to be treated. Although it is preferable for reasons of convenience to embody the selectively controlled hardening agent in the developer solution, it may be used separately if desired, by such modification of the developer solution as will prevent such a hardening of the emulsion as will prevent the selective hardening desired.

It is believed that the hardening or tanning effect of the pyrogallic acid exerts its action first adjacent the so-called latent image, or in other words, on the port-ions of emulsion adjacent the particles of silver salts affected by the exposure light and converted by the developer into metallic silver. Thus in a silver bromide film, the throwing off of the bromide from a light-affected silver bromide particle in the developing process probably reacts with the pyrogallic acid to harden or tan or render insoluble or unremovable the adjacent emulsion. Thus in 105 the embodiment chosen for purposes of illustration, the reaction products from the chemical effects of the developer solution, are believed to react with the selectively controlled hardening agent. the essential result being a hardened emulsion surface corresponding to the lights and shades to be reproduced which will acquire and give up any desired color in a comparatively short time. By controlling the hardening or tanning effect of the pyrogallic acid as above set forth, only the particles of emulsion adjacent the said light-affected particles of silver salts are hardened, the relative proportions of the hardening agent (whether or not accelerated by an accelerating agent) and of the neutralizing agent being such as to control selectively the effective area of influence of the hardening agent. The unhardened portions, as stated above,

removed in any desired manner as by placing the emulsion in warm water which causes the unhardened or soluble portions to soften and melt away from the hardened or insoluble portions so that the hardened then may mamas emulsion be hardened which are adjacent the carrier for the emulsion, which may be accomplished in various ways, some of which are dlsclosed in my copendmg applications for Letters Patent Serial No. 313,239, filed July 25, 1919, for a thin mounted sensitized emulsion; Serial No. 313,240, filed July 25,

1919,;for process of makin'g a contact transfer printing surface by complementary light;

Serial No. 327,891. filed October 2, 1919, for potassium iodide formula for photographic processes, process of using same, and article obtained thereby; Serial No. 332,806, filed October 23, 1919, for process of making a contact transfer printing surface with a colored emulsion, and amon'g which may be mentioned the exposure of the sensitized emulsion through its transparent carrier and the limitation of the depth to which the rays of exposure light penetrate by having the actinic rays of the exposure light and the emulsion complementary in color.

If desired the hardened emulsion may be fixed to remove the silver salts unaffected by light, and bleached to remove the black mein}; out the printin tallic silver. This may be done in well known manner, and while not necessary, is of advantage as it enables the operator ,to watch the effect of the coloring matter on the printing surface to which it is applied for carryprocess.

The order of melting, bleaching, and fixing is not important and may be carried out in any order desired, although it generally is more convenient to fix, melt, and bleach, in the order named.

The printing of positives from the printing surface may be done by direct contact. The printing surface is exposedto the action of the desired coloring matter as by placing it in or carrying it through a liquid color bath. The colored surface then is placed in contact, preferably under some pressure, with the substance on which the positive is to be made, as by a roller or by a squeegee action. As stated above, the printing surface prepared by my process receives and gives up the colormg matter almost instantly as distinguishcd from other processes which take an appreciable length of time.

Natural color efi'ects may be produced in well known manner, such for example as by exposure through color screens with subsequent treatment and manipulation to obtain the desired results.

Many modifications of my invention will be apparentto those skilled in the art without departing therefrom or from the scope of theclaims, my invention not being limited to the embodiments thereof chosen for purposes of illustration but consisting of a process for forming a printing surface on a negative capable of acquiring and giving up a desired color with great rapidity.

Having described one embodiment of my invention, what I claim is:

1. The process of forming a photographic record of lights and shades capable of use as a transfer printing plate, which comprises developing an exposed photographic emulsion with a non-emulsion-hardening solution, exposing it to an actinic light, and then hardening portions of emulsion adjacent the light affected sensitive content of the emulsion with an agent adapted to harden said emulsion by reaction with the light affected sensitive content of the emulsion, and with a neutralizing agent for said hardening agent, the relative proportions of said hardening and neutralizing agents being such as to control selectively the effective area of influence of the hardenin agent but to an extent less than the complete neutralization of said hardening agent.

2. The process specified in claim 1 in which the sensitive content is a silver salt.

3. The process specified in claim 1 in which the hardening agent is pyrogallic acid.

4;. The process specified in claim 1 in which the neutralizing agent is sodium sulphite.

5. The process specified in claim 1 in which the hardenin agent is pyrogallic acid and the neutra izing agent is sodium sulphite.

6. The process specified in claim 1 to which is added the step of removing the unhardened portions of emulsion subsequent to said treatment.

In testimony that I claim the foregoing, l have hereunto set my hand this 30 day of September, 1919.

ROBERT JOHN.