Radiation imagery chemistry: process – composition – or product th – Transfer procedure between image and image layer – image... – Diffusion transfer process – element – or identified image...
Reexamination Certificate
2001-04-16
2003-04-01
Schilling, Richard L. (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Transfer procedure between image and image layer, image...
Diffusion transfer process, element, or identified image...
C430S022000, C430S212000, C430S220000, C430S221000, C430S222000, C430S227000, C430S241000, C430S244000, C430S952000
Reexamination Certificate
active
06541177
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to diffusion transfer photographic film units and methods, and, more specifically, to such film units ,and methods which utilize them, which include a latent image which becomes visible upon photographic processing of the film unit.
There are known in the art diffusion transfer photographic film units which include latent images which become visible upon photographic processing of the film unit. U.S. Pat. No. 5,142,311 discloses such a film unit which has a first area exposed to light during manufacture of the film. Following exposure of a second area of the film unit to a subject while the first area is masked so as not to be further exposed and photographic processing of the film unit a composite image is formed comprised of the developed latent image and the image of the subject. The latent image may be any desired image.
As the state of the self-developing, diffusion transfer photographic art advances new uses are proposed for diffusion transfer film units generally and, in particular, film units which include a latent image. It would be desirable to have diffusion transfer photographic film units wherein the visible image obtained from a latent image as a result of photographic development may be transient or permanent. It would also be desirable to have diffusion transfer photographic film units which can provide composite images with only one exposure of the film unit.
SUMMARY OF THE INVENTION
These and other objects and advantages are accomplished in accordance with the invention by providing a self-developing diffusion transfer photographic film unit which includes a latent image formed by a chemical compound. The latent image is adapted to form a visible image upon photographic processing of the film unit. The visible image formed from the latent image may be transient, i.e., it will be visible for some period of time during and after photographic development but will then disappear, or permanent, i.e., a composite final image is obtained which includes a visible image corresponding to the latent image and an image of the subject of the exposure.
The latent image may be formed with any of various suitable chemical materials including, for example, indicator dyes, bleachable filter dyes and bleachable indicator dyes. The latent image may be disposed in any suitable location within the self-developing, diffusion transfer photographic film unit. It is preferred to arrange the latent image in the image-receiving element of the film unit.
The self-developing diffusion transfer film units of the invention may be “peel-apart” film units, i.e., those where the image receiving element is designed to be separated from the photosensitive element after the photosensitive element is exposed and photographic development is effected or “integral” film units, i.e., those where the photosensitive and the image-receiving elements are designed to be maintained together when image formation is completed. Further, the film units of the invention may be adapted to provide black and white or color, including multicolor, images.
There are also provided according to the invention diffusion transfer photographic methods for forming composite photographs with only a single exposure of a film unit.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The latent image incorporated in the self-developing, diffusion transfer photographic film units of the invention may be provided by any suitable chemical material which will provide a visible image, whether transient or permanent, during and after photographic development brought about by application of an aqueous alkaline photographic processing composition to the film unit. Typical suitable chemical materials which can be utilized to form the latent image include indicator dyes, bleachable filter dyes and bleachable indicator dyes. The latent image can be incorporated in the diffusion transfer film unit during the manufacture or assembly thereof. The latent image may be of any type including a greeting, advertising indicia, a vignette, a symbol or the like.
An indicator dye, generally speaking, is one which undergoes a reversible color change at different pH levels. It is well known to use indicator dyes in diffusion transfer photographic film units for the purpose of protecting a selectively exposed photosensitive material from post-exposure fogging in photographic methods where development is conducted in the presence of extraneous incident light such as is the case with integral diffusion transfer photographic film units which are ejected from the camera after exposure and application of a photographic processing composition such that development takes place in ambient light. See, for example, U.S. Pat. Nos. 3,702,244; 3,702,245 and 3,726,675. It is also well known that in the diffusion transfer photographic development process the pH of any particular location within the film unit varies with time. Typically, the aqueous alkaline processing composition employed in the development step has a very high pH, e.g., from about 13 to 14, and during development each layer of the multilayer film unit goes through a broad range of pH which includes very high pH levels and relatively low pH levels and ultimately approximately neutral pH.
In a preferred embodiment of the invention the latent image is formed with an indicator dye. The indicator dye preferably has a pKa of from about 10 to about 13 and also preferably is one which decolorizes completely at neutral pH. Accordingly, in this preferred embodiment there is provided a transient visible image which can be seen by an observer as the visible image of the object of the exposure is developing and which then disappears.
In another preferred embodiment of the invention the latent image is formed with a bleachable indicator dye. Bleachable indicator dyes and their use in photography, including diffusion transfer photographic film units, are well known. See, for example, U.S. Pat. Nos. 4,139,381; 4,178,446 and 4,178,447. A bleachable indicator dye is typically colorless at low pH, e.g., neutral pH, becomes colorized at high pH, e.g., pH 12-13, and will bleach, or decolorize, irreversibly by hydrolysis when maintained at high pH for a period of time. The combination of an indicator dye moiety and a bleachable dye moiety in one molecule allows the initiation of the process to provide a visual image from the latent image to be pH-dependent whereas the completion of this process is hydrolysis-dependent. Accordingly, the time that the image obtained from the latent image remains visible can be independent of the pH drop in the development process. A particularly preferred bleachable indicator dye for use according to the invention is 3,3-bis (4-hydroxy-3,5-dimethoxyphenyl)- 1,2-benzisothiazole-2 (3H)-carboxylic acid-1,1-dioxide, 2-(methylsulfonyl) ethyl ester.
Bleachable filter dyes comprise another preferred class of compounds for froming a latent image according to the invention. A bleachable filter dye typically is colored at low pH, e.g., neutral pH, and decolorizes by hydrolysis at high pH, e.g., pH 12-13. These compounds may be used to provide a visible image corresponding to the latent image. Since bleachable filter dyes are colored at low pH, it is preferred to incorporate the latent image formed with these compounds in the film unit in a location such that exposure of the photosensitive element to an object is not made through the latent image.
Diffusion transfer film units typically are made by initially manufacturing separate photosensitive and image-receiving elements and subsequently assembling these, together with a rupturable container containing the aqueous alkaline processing composition, to form the complete film unit. The latent image can be formed in any suitable location within the film unit, i.e., in the photosensitive element and/or in the image-receiving element. It is preferred to provide the latent image in the image-receiving layer of the image-receiving element.
The latent image can be formed in the film unit during the manufacture of the ph
Filosa Michael P.
Foley James A.
Marshall John L.
Telfer Stephen J.
Waller David P.
Polaroid Corporatiion
Schilling Richard L.
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