US3843370A - Instant access one-layer color photography with color screen containing color couplers - Google Patents

Abstract

COUPLING WITH THE OXIDATION PRODUCT OF A PARAPHYNYLENEDIAMINE COLOR DEVELOPER, A DYE COMPLEMENTARY IN COLOR TO THE PRIMARY COLOR OF THE OIL DROPLET.

1. A LIGHT SENSITIVE PHOTOGRAPHIC ELEMENT COMPRISING A TRANSPARENT FILM BASE CARRYING, IN THE FOLLOWING ORDER: (1) A PANCHROMATICALLY SENSITIZED SILVER HALIDE EMULSION LAYER WHICH IS IN CONTIGOUS CONTACT WITH (2) A MULTICOLOR SCREENING LAYER MADE OF RED, GREEN AND BLUE COLORED OIL DROPLETS, EACH DROPLET CONTAINING NON-DIFFUSING DYE HAVING ONE OF THE PRIMARY COLORS TOGETHER WITH A COLOR FORMER FAST TO DIFFUSION WHICH BECOMES DIFFUSING AT A PH OF AT LAST 12.5, AND IS CAPABLE OF FORMING UPON

Description

Oct. 22, 1974 B. H. wAxMAN ETAL- l 3,843,370

INSTANT ACCESS ONE-LAYER COLOR PHOTOGRAPHY WITH COLOR vSCREEN CONTAINING COLOR COUPLERS Y med Feb. 2e, 197s s sheets-sneet 1 Oct. Z2, 1974 a. H. wAxMAN ETAL INSTANT ACCESS ONE-LAYER COLOR PHOTOGRAPHY WITH COLOR SCREEN COHTAINING COLOR COUPLERS Filed Feb. 26, 1975 3 Sheets-Sheet 2 F/G. 6 C' *i 22 WM mw. WMMAN Erm 3,843, INSTANT ACCESS ONE-LAYER COLOR PHOTOGRAPHY WITH COLOR. SCREEN CONTAINING COLOR COUPLEBS Fild Feb.. 26, 1975 3 sheets-sheet s nited States Patent O INSTANT ACCESS ONE-LAYER COLOR PHOTOG- RAPHY WITH COLOR SCREEN CONTAINING COLOR COUPLERS Burton Harvey Waxman and Robert Thomas Shannahan, Endicott, and Felix Viro, Apalaehin, N.Y., assignors to GAF Corporation, New York, N .Y.

Original application June 15, 1971, Ser. No. 153,186, now Patent No. 3,728,116. Divided and this application Feb. 26, 1973, Ser. No. 335,641

Int. Cl. G03c 1/40, 1/84; G03f 5/00 U.S. Cl. 96-77 4 Claims ABSTRACT OF THE DISCLOSURE An instant access diffusion transfer process for photographic materials in lwhich multicolor dye images are produced in a transfer sheet by exposing a panchromatically sensitized silver halide emulsion through a single multicolor, color former containing screen layer, subsequently developing the emulsion at a high pH and transferring the color formers from the screening layer to an unsensitized receiving sheet.

This application is a Division of our copending application Serial No. 153,186 led June l5, 1971, now U.S. Pat. No. 3,728,116 entitled Instant Access One-Layer Color Photography.

The present invention relates to color photography, and especially to a color diffusion transfer process by which unreacted color former(s) corresponding to the unexposed or partially exposed areas of a color negative are diffused imagewise, after color developing the negative, to a transfer sheet in which the color former(s) are reacted with oxidized color developer to produce positive dye images.

The use of the diffusion transfer process, described in United States Patent Specification No. 2,352,014, has been found to be very effective in black and white photography. This is particularly true in the system of E. H. Land of the Polaroid Corporation which employs pods of the processing chemicals between the light sensitive element and the transfer sheet.

Multicolor systems are known using monoor multilayer coatings containing differently sensitized silver halide emulsions and corresponding color formers capable of yielding dyes complementary in color to the light rays to which each emulsion is sensitized, a color former being incorporated and dispersed in resinous or oily packets throughout the emulsion with the silver halide grain either incorporated in the colloidal carrier (gelatin or gelatin substitute) of the emulsion, or in the resinous packets. The latter technique based on this process is generally referred to as packet or mixed grain emulsion technique. Such technique is described, for example, in British Patent Specification 864,060, in British Patent Specification 718,404, French Patent Specification 1,080,967 and U.S. Patent Specification 1,080,967 and U.S. Patent Specification 2,490,749; 2,544,640; 2,698,794; 2,698,795; 2,698,797; 2,798,544 and 2,322,027. These patent specifications indicate the steps to be followed and the oils ice to be used in preparing the packet or mixed grain emulsions.

Other methods are known wherein a single multicolor print may be reproduced by exposing three negatives through three light filters and pressing the development negative into contact with a transfer sheet containing a color former. This system requires at least three separate steps and is obviously not a one-step instant access process.

In order to produce instant access color prints, the prior art employs several layers of differently sensitized silver halide emulsions.

We have now found that with the use of a unique dual action screening layer it is possible to produce multicolor positive prints by the diffusion transfer process. This dual action screening layer acts as both a multicolor light filter system capable of screening specific light waves and as a provider of color formers yielding complementary dyes in accordance with the requirements of this invention. The screening layer and a panchromatically sensitized silver halide emulsion layer constitute the photosensitive element, or negative material.

In conjunction and coordination with the photosensitive element are special color formers which reside in the screen and become diffusible upon treatment with high pH solution in accordance with the requirements of the diffusion transfer process herein disclosed. The color formers incorporated within the screen are positioned in a point to point relationship with the dyes to which they form complementary colors when reacted with oxidized color developer.

A diffusion transfer process which produces multicolor dye images in a transfer sheet by exposing a panchromatically sensitized silver halide emulsion through the aforesaid screening layer, and development at high pH constitutes the object of this invention.

In commercial color photography, the color formers are either of the hydrophilic type, eg., those solubilized by alkalies or of the hydrophobic or lipophilie type, eg., those dissolved in oils of the type described in for instance U.S. Patent Specification 2,322,027, and are of such high molecular weight that they resist diffusion from the emulsions even at a high pH. The. color former(s) which We employ and which have been characterized above as of a special type, partake in part of the characteristics of the lipophilic color formers of the prior art, but are of a much lesser molecular weight so that at high pH, i.e., 12.5-13, they are diffusible in an aqueous medium. Specifically, the color formers which we use must possess the following attributes: (1) medium molecular weight, (2) freedom from Water solubilizin-g groups, such as carboxy or sulfonic acid groups, (3) sufficiently oil solu- 'ble to be incorporated in resinous or oily packets, (4) contain such groups which at high pH (12.5-13) are able to form an alkali metal salt which renders the color former molecule diffusible in aqueous medium, e.g., groups such as phenolic hydroxyl and enolic hydroxyl, and (5) produce non-diffusible dyes with conventional primary aromatic amino color developing agents, such as N-diethyl-p-phenylene-diamine; N-ethyl-N--hydroxyethyl-p-phenylenediamine and N-diethyl-3-methyl-pphenylenediamine and the like.

Examples of couplers contemplated for use according to the present invention and which meet the above attributes include the following:

r r (11N H(CHz)eNH (l) 07H15 l) CHBCHi (IEH- til-NH- lCIJ- cin N C=o o Ir CH3 o O l fiom pmu@ l CHQNS oz- III The compounds I, II, and III are the preferred color formers, but other color formers can be selected by a simple test. Thus, couplers which are free from solubilizing groups, but are sufficiently soluble in an oil and which diffuse only at the high pH specified would be adequate for use, such as those listed in U.S. Pat. 3,301,772.

No diffusion of these couplers results during preparation of the sensitized element or negative color development if initially effected at a pH of 10.0-11.5, a condition which excludes the usev of color formers which are soluble in solutions of low alkalinity. Such color formers which are thus excluded are, for example, of the type described in U.S. Patent Specification 2,186,849. On the other hand, diffusion of our couplers ensues as soon as the pH of the environment reaches or exceeds 12.5. This excludes the lipophilic type color formers of high molecular weight presently used in commercial color products which are not dilusible regardless of the pH. Accordingly, in our procedure the color formers which are not reacted during color development of the negative image are free to diffuse to the receiving sheet when the pH is at 12.5-13. The diffusion of the unused couplers is, therefore, caused, not by structural modifications of the color former molecule, but by the pH of the surrounding medium. The diffused color formers will form a positive dye image modulated by imagewise oxidative coupling and immobilization in the emulsion layer on a contacting unsensitized transfer sheet in the presence of an oxidizing agent and unused color developer.

Generally speaking, the quantity of color former used per unit of silver halide is Selected in such a Way that maximum density in the high light regions of a subject, or the transparent portions of a pattern, is achieved on exposure of the color negative material to the subject, or to the pattern and color developing such areas to maximum density. Thus, in the areas of exposure yielding maximum density on color development al1 of the color former will be used up while diffusing through the emulsion layer and none is left over for transfer. In other areas, the unused coupler will diffuse and be imagewise received in the transfer sheet. Consequently, where maximum density is achieved in the negative materials, no dye image will form in the transfer sheet. Dye images will only form in the transfer sheet to the extent that the coupler remains unreacted while diffusing during the color development through the negative silver halide element. Specifically, it is recommended that with a screen coating of from 0.4 to 0.8 micron in thickness, about 0.4-0.8 g. of color former/m.2 be used. This requires in practice about 0.71.5 g. AgX/m.2 in the emulsion coating. Using emulsions with Ag/gelatin ratio of 0.70 this would require an emulsion coating of thickness of 2.0-4.0 microns.

Preferred forms of this invention will be more fully understood by reference to the accompanying drawings in which:

FIGS. 1, 2, 3, 9 and 10 discloses cross sectional views of the instant access photographic element showing several alternative ways of obtaining lateral reversal of the image and the individual layer arrangement for carrying each out, and which constitutes several physical embodiments of the invention.

The screening layer can be coated on a film base, as in FIGS. 1 and 9, or the panchromatic emulsion layer as in FIGS. 2, 3 and 10.

In the assembly represented in FIGS. 1 and 2, the positive receiving material is then pressed film base up in contact with a while cardboardl material which becomes reflective base for the print. In the case described in FIG. 3, the stripped positive receiving sheet is the new print which could be mounted later to a more rigid cardboard base.

FIGS. 9 and 10 describe systems similar to the ones in FIGS. 1 and 2 except that the white opaque reflectance is created not by paper base added later, but is obtained by incorporating white pigment, such as TiO'z in a layer through which the color former has to diffuse before forming a positive transfer image. Processing as in FIGS. 2 and 10 incorporates a positive receiving sheet underneath the negative element.

FIG. 4 pictorially shows that is happening during the development process to the attened out and lightly packed oil droplets within the gelatin membrane of the oil screen, pointing out that in the dry state maximum filtration is obtained whereas during processing the supply of color former for diffusion is contracted because of gelatin swelling characteristics. This helps to reduce sidewise diffusion exposure and during the diffusion step.

FIG. 5 pictorially describes and defines the various layers referring to FIGS. l, 2, 3, 9 and `10.

FIGS. `6, 7 and y8 are schematic representations of equipment, a pod, used in evaluating coatings, and for the mechanical pressure and developer contacting apparatus for evaluating and processing the coatings in the transfer system, and could be used inside or outside of the camera, and a camera reproduction work.

FIG. 7 shows a mechaincal pod device wherein a or b are soft rollers, and c is a stainless steel tube of 1A diameter and closed at one end perforations in one roW facing the rubber rollers.

FIG. 8 is a perspective view of the stainless steel tube c shown in FIG. 7. The open end is connected to a repeater syringe filled with viscous developer and adjusted to measure out enough viscous developer to be spread evenly between inserted negative photosensitiveelement A and contacting material B. The latter sheets are of suc'h width as to snugly fit between the two nylon roller end plates which keep the developer confined in volume d.

A discussion of the photographic layers which are used in the several alternative arrangements according to the invention, such as depicted in FIGS. 1, 2, 3, 9 and 10, is provided so that the physical behavior of the chemicals and apparatus may be better understood.

Layer I is a transparent lm base, such as polyester cellulose acetate, cellulose acetate butyrate, and the like, with a thickness of 21/2-9 mils.

Layer 2 is the oil droplet screen layer containing screening dyes and color couplers. Coating the screen to 4-8 microns thick coated about 0.4-0.8 g. coupler/m2, with oil droplet sizes from 5-l5 microns.

Layer 3 is the panchromatically sensitized emulsion layer. The emulsions intended for use herein are:

Panchromatically sensitized bromo iodide emulsion of average crystal size 0.4-1.0 micron, containing 4-12 mole percent iodide, gold and sulfur sensitized.

Panchromatically sensitized bromo chloride emulsion of average crystal size 0.2-0.5 micron containing 70-90 mole percent bromide.

Panchromatically sensitized bromo chloride emulsion of average crystal size of 0.20.5 micron and containing -40 mole percent bromide.

With the layer thickness and concentration levels of the coupler in layer 2, the requirement in practice of the emulsions are about 0.7-1.5 g. of Ag/m.2 emulsion coating. Using emulsions with Ag/ gelatin ratio of about 0.7, would require a dry emulsion coating thickness of 2-4 microns.

Layer 4. Pod.

Layer 5 is an image receiving layer, and may be composed of gelatin and the like, 8-16 microns thick.

Layer 6 is the encapsulated oxidizer and neutralizer layer, of conventional materials 2-4 microns thick.

Layer 7 is a transparent base or overlay which becomes the protective layer or covering on the positive print after separation.

Layer 8 is a paper base. The materials contemplated relating to FIGS. 1 and 2 would be white cardboard for mounting the stripped print for lateral reversal. IIn FIG. 3, it would be exible single or double weight paper base support.

Layer 9 is an alkali stripping layer 2-4 microns in thickness.

Layer 10 is a contact stripping sheet and may be any flexible composition or lm base which has one side treated so as to cause good adhesion to screen layer (2) when developer is spread between said layers. This allows after the required diffusion time to physically strip off layers (2) and (3) as a new integral packet of (10H-(2) +(3) which is then discarded.

Layer 1l is a white opaque pigment layer containing TiO2, or the like.

The screening layer (2) consists of numerous minute oil droplets (5-15 microns in size) held in place and closely packed within a gelatin membrane (see FIG. 4 and Examples I and II). Upon drying the oil droplets Hatten out and form a mosaic pattern with gelatin membrane between the colored oil droplets. The screen could be coated on a film base as in FIG. 1, or over the panchromatic emulsion layer as in FIGS. 2 and 3.

Within each separate oil droplet is a dye which colors it (such as blue, red and green dyes) and a complementary color coupler (based upon a subtractive color system). The combination of numerous colored oil droplets constitutes a screening device acting as a single layer multilight lter through which the AgX emulsion is exposed.

The screening layer is placed between the AgX emulsion and the object to be exposed, thus the light reaching the AgX emulsion must first pass through the screening layer. Since the droplets are colored, only that light of a specific spectrum of wavelength corresponding to that color is allowed to be transmitted through each oil droplet screen to the underlying AgX emulsion layer. The red dyed droplet transmits only red light, the green droplets transmit green, and the blue blue. The silver halide receiving this actinic colored light is activated according to that of the light reaching it.

If the red oil droplet transmits red light to the silver halide emulsion layer, the cyan color former within it, upon development, diffuses and is coupled by developer oxidized by the AgX activated by that red light transmitted. Thus, the color former of said oil droplet is immobilized, and developed cyan colored (in the negative), and not allowed to reach the transfer sheet. However, the positive will thus develop minus the cyan dye which will appear red when all its color combination densities are transferred to the transfer positive, according to the subtractive dye system, the same logic applies to the other colored droplets and their complementary color couplers therein.

Upon development of the photographic element, the couplers diffuse out of the oil droplets and into the silver halide emulsion layer. The silver halide is non-diffusible imagewise or non-imagewise, and some of the color formers are imagewise intercepted by developer oxidized by the reduced AgX, and become immobilized in place in layer 3 instead of reaching the image receiving layer. The non-immobilized excess of color former which has not been imaged out by color coupling with AgX and developer is thus allowed to diffuse imagewise to the transfer sheet where it reacts with oxidized developer forming positive dyes.

The dyes contemplated for use in this invention Within the colored oil droplets are as follows:

Blue

Sudan Blue CSP Methyl Violet Base Sudan Blue BA Red Sudan Red GGA Sudan Red BBA Note that these filter dyes are non-diffusing at all times, and that the subtractive dyes formed from color formers by the coupling process are non-diffusing under all processing conditions.

The color formers must be non-diffusing under prevailing conditions making screen dispersions, coating the same and for overcoating with other layers. Color formers must be diffusing and alkali soluble in aqueous phase under processing conditions requiring reduction of AgX by paraphenylenediamine type developer, and coupling the latter with color formers.

The process hereof may be carried out by alternative techniques. In one method, it is envisaged that the negative material, after exposure, is contacted by developer of high pH (12.5-13) and developed to maximum density, and is simultaneously brought into contact with the transfer sheet containing an oxidizing agent such as potassium ferricyanide, hydrogen peroxide, potassium dichromate, or the like. The alkalinity of the developer is transferred to the environment of the color formers because their diusion into the AgX emulsion layer, where some are coupled with oxidized developer, and the remainder are received in the transfer sheet.

Another procedure involves initiating developer oxidation, after exposure, by placing the negative material in a color developer solution for 1-3 minutes having a pH of S-11.5, and completing the development by contacting the negative material with a developer solution having a pH of 12.5-13.

For this purpose use may be made of transfer sheet containing a 2% solution of sodium hydroxide, potassium hydroxide, or the like. The transfer sheet is then used to pick up the diffused color former and to provide a medium in which it is converted into a dye image in the presence of an oxidizing agent and unused color former.

Yet another, and the preferred procedure involves color development to be carried out by passing the exposed negative material A (see FIG. 1) and the contacting material B through a roller assembly (see FIG. 6) whereby they have a presoak in the developer solution of 3-5 seconds at pH of 12.5-13, before they are pressed into physical contact under moderate roller pressure. After 1 minute (30 seconds-2 minutes contact, which varies for optimum results on developer temperature), the sheets are pulled apart, this high pH developer having caused diffusion of the couplers into the AgX emulsion layer, and to the transfer sheet where it images out in a positive print. As in FIGS. 1 and 2, the positive receiving material is then pressed film base up in contact with a white cardboard material which becomes reflective base for the print. In this case described in FIG. 3, the stripped positive receiving sheet is the new print which could be mounted later on a more rigid cardboard base.

lIt is thus evident that three different techniques may be resorted to in order to obtain correct transfer color images. The first method is intended to completely immobilize the color former corresponding to the exposed silver halide and then to transfer along with excess developer the imagewise diffusible non-immobilized color former to form the linal image.

The second method is intended to oxidize the developer corresponding to the exposed silver halide in the negative in low pH developer, and then completing the processing by introducing the high pH developer rendering the color formers difusible and Where some are immediately immobilized in the silver halide emulsion, and the remainder diffused, along with excess developer to the transfer sheet.

The third and preferred method does not require imagewise color developer diffusion, and wherein the negative material and the contacting material are simultaneously contacted, after exposure, by a high pH presoak developer solution which renders the couplers dilfusible into the AgX layer and to the transfer sheet where the non-immobilized couplers form a dye image with developer oxidized -by an oxidizing agent encapsulated within the contacting material.

The following examples will further explain the present invention, although it is to be understood that this invention is not restricted to such examples.

Example I The oil droplets for use in the screening component of the aforesaid invention which are to be used in the instant access mono layer color photography are prepared as follows:

A. Blue screen component is made as follows: 0.5 g. of yellow color former (III and 0.15 g. of Sudan Blue CSP and 0.25 g. of Methyl violet base are dissolved in 1.0 cc. of dibutylphthalate and 2.0 cc. of Santicizer 160 (Butyl Benzyl Phthalate) (Monsanto Co.)

by heating on a hot plate. When dissolved, the oil phase is dispersed under slow stirring speed (mechanical) for seconds in 45 cc. of 8% gelatin solution and 6.0 ce. of Alkanol B dispersing agent. (Sodium alkyl naphthalene sulfonate) (E. I. du Pont de Nemours and Co.) Droplet size 5-15 microns. B. Red Screen component is made as follows:

0.7 g. of cyan color former (I) and 0.25 g. of Sudan Red GGA and 0.25 g. Sudan Red BBA are dissolved in 1.0 cc. of dibutylphthalate and 2.0 cc. of Santicizer by heating on a hot plate. When dissolved, the oil phase is dispersed under slow stirring (mechanical) for 100 seconds in 45 cc. of 8% gelatin solution and 2.2 cc. of Alkanol B dispersing agent. Droplet size 5-15 microns.

C. Green screen component is made by dissolving:

0.7 g. of magenta color former (II) and 0.25 g. of cyan dye (IV) and 0.10 g. of yellow dye (V) in 1.0 cc. of dibutylphthalate and 2.0 cc. of Santicizer 160 by heating on a hot plate. When dissolved, the oil is then dispersed under slow stirring (mechanical) for 100 seconds in 45 cc. of 8 gelatin solution and 4.5 cc. of Alkanol B dispersing agent. Droplet size 5-15 microns.

Example l1 The mixed screen layer (2) (see FIG. 1) for use in the instant access mono layer color photography is prepared by mixing:

30 cc. of blue screen dispersion A 30 cc. of red screen dispersion B 30 cc. of green screen dispersion C 9 Example III A photosensitive layer A of Example I is exposed to a subject image, and developed to maximum density for two minutes at 20 C. by spreading the following viscous developer solution onto layer A:

Water to make 1000 cc.

Example IV A photographic element of the type depicted in FIGS. 1 and 10 was prepared utilizing the screen layer prepared in Example II, with layers 2 and 3 comprising the negative photosensitive element A.

Element A is exposed in a step wedge sensitometer and developed to maximum density for two minutes at 20 C. in the following developer:

G. Sodium sulfite 8 Sodium hexametaphosphatel 1 N-ethyl-N--hydroxyethyl-p-phenylene-diamine 5 Sodium carbonate, monohydrate Sodium bromide 1 Water to make 1000 cc.

the developer has a pH of 10.7.

The developed strip, without working, is pressed into contact for three minutes with a transfer sheet of baryta coated paper 'B, presoaked for five minutes in a 2% aqueous solution of sodium hydroxide. This provides a pH in the environment of the photosensitive element of 12.5-13, i.e., sufficiently high pH to cause the color former to migrate through the emulsion layer, and those which are not immobilized in the emulsion layer diffuse to transfer sheet.

The transfer sheet is then separated from the negative coating and placed for one minute in a 1% solution of potassium ferricyanide which oxidizes the developer present in the transfer sheet. Reaction between oxidized developer and diffused color formers produce visible positive image with tone values corresponding to the original.

Example V A photographic element of the type depicted in FIG. 1 was prepared by utilizing the screen layer prepared in Example II, with layers (2), and (3) comprising the negative photosensitive element A, and layers (5), (6), and (7) comprising the contacting material B. Color development is carried out, after exposure of the photosensitive element to a subject image, by passing the exposed negative material A and contacting material B through a roller assembly y(see FIG. 6), whereby they 75 10* have a 3-5 second presoak in the following highly alkaline viscous developer solution.

G. 'Sodium sulte 8 Sodium hexametaphosphate 1 N-ethyl-N--hydroxyethyLpphenylene-diamine 5 Sodium carbonate, monohydrate 10 Sodium bromide- 1 Sodium hydroxide 17.5

Water to make 1000 cc.

before they are pressed into physical contact under moderate roller pressure. The developer has a pH of at least 12.5. After one minute contact time, at 20 C., the sheets are pulled apart.

Referring to FIG. 1, when developer (4) is spread be- :tween A and B and the negative element and the contacting material are squeezed together, color developer and alkali start diffusing into the swelling emulsion layer (3) and into the image receiving layer (5). By the time exposed silver halide crystals start developing and thereby producing oxidized color developer, alkali has reached color former filter layer (2), mobilizing color former from oil droplets and letting it diffuse out into the emulsion layer where it will couple with oxidized developer, where present, to form immobile dye. Where no exposure had taken place, color former moves on through the emulsion layer into the image receiving layer (5) and the layer containing encapsulated oxidizer (6). In the latter layer, slow release of oxidizer takes place creating a low concentration of oxidized developer which couples with the color former forming immobile positive dye image.

The removal of color former :in the receiving layer helps to establish concentration gradient which helps to gain high maximum density in the receiving layer. At the end of development time (l minute) color former concentration in the original screen layer has dropped to very 1low level since it was being used up as fast as it diffused out, forming negative dye image in the negative element and a positive dye image in the receiving layer. Side-wise diffusion is kept at the minimum for several reasons:

1. Alkalinity front moves in from emulsion side exposing a large area of the oil droplet to high alkalinity and will start diffusion to front side only.

2. As alkalinity penetrates between the droplets, gelatin swells and causes physically bigger distance between the droplets which at this stage return to their spherical shape (see FIG. 4).

It will be evident that the process contemplated herein may be effected in a camera or in a copying device. The only requirements are the ability to expose the sensitized material, develop the same and to contact the developed material at a high pH with a transfer sheet in the presence of an oxidizing agent.

We claim:

1. A light sensitive photographic element comprising a transparent film base carrying, in the following order: (l) a panchrornatically sensitized silver halide emulsion layer which is in contiguous contact with (2) a multicolor screening layer made of red, green and blue colored oil droplets, each droplet containing non-diffusing dye having one of the primary colors together with a color former fast to diffusion which becomes diffusing at a pH of at least 12.5, and is capable of forming upon coupling with the oxidation product of a paraphenylenediamine color developer, a dye complementary in color to the primary color of the oil droplet.

2. A light sensitive photographic element carrying on a transparent base in the following order (l) a multicolor screening layer containing separate red, green and blue colored oil droplets, each droplet containing in addition to one of the non-diffusing primary color dyes a color former fast to diffusion at a pH below 12.5 which becomes diffusing at a pH of at least 12.5 and is capable of forming upon coupling with the oxidation products of a paraphenylenediamine color developer a dye complementary in color to the primary color of the oil droplet, said screen layer being overcoated with (2) a panchromatically sensitized silver halide emulsion layer, said emulsion layer being outermost.

3. A photographic element as defined in claim 1 wherein said droplets are 5-15 microns in size.

4. A photographic element as defined in claim 2 wherein said droplets are 5-15 microns in size.

References Cited UNITED STATES PATENTS 3,728,116 4/-1973 Waxman et al. 96-3 2,968,554 1/1961 Land 96-3 5 3,301,772 1/1967 Viro 96-3 3,359,104 12/1967 Viro 96-3 3,709,693 1/1973 BlOom et al. 96-3 10 RONALD H. SMITH, Primary Examiner R. L. SCHILLING, Assistant Examiner U.S. Cl. X.R.

Claims (1)

1. A LIGHT SENSITIVE PHOTOGRAPHIC ELEMENT COMPRISING A TRANSPARENT FILM BASE CARRYING, IN THE FOLLOWING ORDER: (1) A PANCHROMATICALLY SENSITIZED SILVER HALIDE EMULSION LAYER WHICH IS IN CONTIGOUS CONTACT WITH (2) A MULTICOLOR SCREENING LAYER MADE OF RED, GREEN AND BLUE COLORED OIL DROPLETS, EACH DROPLET CONTAINING NON-DIFFUSING DYE HAVING ONE OF THE PRIMARY COLORS TOGETHER WITH A COLOR FORMER FAST TO DIFFUSION WHICH BECOMES DIFFUSING AT A PH OF AT LAST 12.5, AND IS CAPABLE OF FORMING UPON

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