US3369472A - Photographic method of exposing photosensitive image-recording sheets - Google Patents

Description

7 3,369,472 ING PHOTOSENSITIVE E. H. LA

OD OF EXP RECORDING SHEETS Filed March 26 1962 Feb. 20, 1968 PHOTOGRAPHIC M IM Original FIG. I

- INVE TOR. 6M1.

ATTORNEYS F I G. 2

United States late'fit T) PHOTOGRAPHIC METHOD OF EXPOSING PHOTO- This application is a continuation of my application Ser. No. 182,243, filed Mar. 26, 1962, now abandoned.

This invention relates to photographic methods of exposing and treating photographic image-recording sheet material to produce photographic prints.

A widely practiced method of producing photographic transfer prints entirely within a camera involves a socalled dry process in which a processing liquid is distributed between an area of a photographic image-recording sheet exposed to produce an image in said area and an image-receptive sheet designed to support a transfer image comprising image-forming substances formed by reaction of the processing liquid with the photosensitive material of the image-recording sheet and then transferred by diffusion to the image-reception sheet. Photographic prints customarily comprise a rectangular image surrounded by a blank, image-free border, on a rectangular sheet large enough to accommodate the image and border. When producing such prints by a diffusion-transfer process, it has been the practice to employ image-recording and imagereceiving sheets of approximately the same width and at least equal in width to one dimension of the print including the border. An area of the image-recording sheet, slightly larger than the desired transfer image, is exposed to produce an image in the area. The image-recording sheet is then superposed with an image-receptive sheet and the processing liquid is distributed between and in contact with an area of the image-recording sheet including the exposed area and a corresponding area of the imagereceptive sheet. The border around the transfer image is achieved by providing a masking layer, usually a separate sheet, between the image-recording and image-receptive sheets for preventing transfer of image-forming substances from the image-recording sheet to those areas of the image-receptive sheet which comprise the border. The processing liquid is supplied between the sheets in a mass located adjacent a transverse edge of the exposed area of the image-recording sheet and is distributed from the mass between the sheets by moving the sheets in superposition, relative to and between a pair of juxtaposed members. Following distribution of the processing liquid, the sheets are retained in superposition for a predetermined period during which transferable image-forming substances are produced from photosensitive material (usually unexposed) in the image-recording sheet and are transferred by diffusion to a layer on the image-receptive sheet to form a transfer image (usually a positive) on the image-receptive sheet.

This method of producing photographic prints is, in some respects, inherently wasteful and unnecessarily expensive, due in part to the necessity of providing a masking sheet, the elimination of which would materially reduce the cost of each print produced. The presence of the masking sheet not only represents an intrinsic expense, particularly with respect to manufacture, but it raises problems in the use of the film in a camera, particularly locating predetermining areas of the image-recording sheet in position for exposure and then registering these areas with the mask so that the transfer images are formed within the borders defined by the mask.

An object of the invention is to provide, in a photographic method of photo-exposing an area of a photosensitive image-recording sheet and thereafter treating it in conjunction with a second sheet to produce a transfer image on the second sheet, a novel and improved method of so exposing said image-recording sheet as to produce image-free borders on said second sheet surrounding said transfer image.

Another object of the invention is to provide a method of the type described in which the image-recording sheet is moved intermittently to locate a succession of areas thereof in position for image-forming exposure, and is exposed continuously to actinic radiation at an intensity level insufficient to produce an image in the image-recording sheet during movement thereof to form image-free .borders on the transfer print.

Other objects of the invention will in part be obvious and will in part appear hereinafter.

The invention accordingly comprises the process involving the several steps and the relation and order to one or more of such steps with respect to each of the others which are exemplified in the following detailed disclosure, and the scope of the application of which will be indicated in the claim.

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawing wherein:

FIGURE 1 is a somewhat schematic view, partially in I section, of photographic apparatus in the form of a camera for practicing the method of the invention; and

FIG. 2 is enlarged sectional View of a portion of FIG- URE 1.

Reference is now made to FIGURES 1 and 2 of the drawings wherein there is illustrated photographic apparatus in the form of a small, compact, hand-held camera lit capable of practicing the method of the invention. Camera 10 comprises a housing including a forward wall 12 having a recessed or re-entrant section 14 extending rearwardly to an inner forward wall 16, side walls 18 and a rear wall 20. The walls of the housing cooperate to provide chambers designated 22 and 24 at opposite ends of the housing and an exposure chamber located between inner forward wall 16 and rear wall 20. Camera 10 includes a conventional lens and shutter assembly designated 26 coupled to the camera by a bellows 28 joined to assembly 26 and to inner forward wall 16 around the edges of an aperture 30 provided in inner wall 16 for transmitting light from the lens to a photographic imagerecording sheet positioned within the exposure chamber between inner forward wall 16 and rear wall 20. The bellows and the camera housing may be constructed as shown so that the shutter assembly can be displaced from the extended operative position shown in FIGURE 1 to a folded or closed position at which the bellows is collapsed within the recess described.

In the operation of camera 10, a supply of a photo graphic photosensitive image-recording sheet material of a conventional type comprising, for example, a gelatino silver halide emulsion carried on a flexible support, is stored in chamber 22. This photosensitive image-recording sheet, herein designated 32, is preferably supplied in a coiled condition on a spool 36 which is mounted for rota tion within chamber 22. Sheet 32 extends from chamber 22 to the rear of wall 16between the latter and rear wall 20 across exposure aperture 30 to chamber 24 at the opposite end of the camera housing.

The image-recording sheet may, as previously indicated, have a width which is substantially equal to the width of the image to be formed on the sheet by exposure thereof in the camera; and for this reason, provision is made for supporting theimage-recording sheet in position for exposure by means located behind the image-recording sheet and which do not interfere with exposure of the sheet to its lateral edges. These means comprise an inner forward surface of rear wall 20 which is positioned so that an area of the image-recording sheet, held against the forward surface of the rear wall, will be positioned with the forward surface of the sheet at approximately the image surface of the lens. The forward wall is convexly curved toward the lens, and means are provided for applying tension to a section of image-recording sheet extending across the curved surface of the inner wall. The inner surface of rear wall 20 is substantially cylindrical and the curvature is preferably slight (i.e., its diameter is large) so that the forward surface of the photosensitive sheet is not displaced so far out of the image surface (usually a plane) of the lens as to cause more image distortion than can be tolerated. The means for applying tension to the photosensitive sheet to retain it against rear wall 20 include a guide roll 34 located adjacent rear wall 20 at the entrance to chamber 24 and an exposure means 38, to be described fully hereinafter, disposed at the opposite end of the exposure chamber at the entrance to chamber 22.

The photosensitive image-recording sheet is exposed (to its lateral edges if desired), and is treated following exposure with a fluid distributed between the imagerecording sheet and a second or image-receptive sheet superposed therewith. A supply of this second sheet, designated 40, is provided within chamber 24 together with means in the form of a pair of juxtaposed members for superposing the photosensitive and second sheets and aiding in the distribution of a processing liquid in a layer between the sheets. In the form shown, the juxtaposed members comprise a pair of pressure-applying rolls 42 and 44 mounted in juxtaposition within chamber 24 adjacent guide roll 34 near the entrance to the exposure chamber between Wall 16 and rear wall 20. Photosensitive sheet 32 is guided from spool 36 within chamber 22 between exposure means 38 and the inner surface of rear wall 20 through the exposure chamber, between guide roll 34 and rear wall 20, and around pressure-applying roll 44 between rolls 42 and 44 toward the rear of the housing. Second sheet 40 extends within chamber 24 into superposition with image-recording sheet 32 at the bite of rolls 42 and 44 and extends in superposition with the image-recording sheet between the pressune applying rolls. A withdrawal passage 46 is provided in rear wall 20 in alignment with the gap between rolls 42 and 44 to permit withdrawal of sheets 32 and 40 from the housing. The sheets, as shown, are guided along convergent paths into superposition at the bite of the pressure-applying rolls, and it is between the convergent portions of the sheets at the bite of the rolls that the fluid-processing composition is introduced.

In embodiments in which image-recording sheet 32 is substantially equal in width to the width of the image to be produced, roll 44 includes a cylindrical pressureapplying surface substantially equal in length to the width of sheet 32. The camera is designed to produce a succession of rectangular photographic prints each comprising a rectangular transfer image supported on sheet 40 and surrounded by a sharply defined image-free border. The width of the image-receptive sheet accordingly is equal to the combined widths of the image and the lateral borders, and roll 42 includes a pressuresap-plying surface which is at least equal in length to the width of image receptive sheet 40. The pressure-applying rolls are so positioned with respect to one another and the other components of the camera that the lateral edges of the imagereceptive sheet coincide with the ends of the pressureapplying surface of roll 44; and the lateral marginal portions of sheet 40 extend equal distances beyond the ends of the pressure-applying surface of roll 44 and the lateral edges of sheet 32. I

The transfer image comprising each positive print is preferably formed by a diffusion-transfer reversal process in which reagents in a liquid distributed between the image-recording and image-receptive sheets react with the photosensitive material to produce image-forming substances which are transferred by diffusion to a layer on the image-receptive sheet. Typical of such processes is silver halide diffusion-transfer reversal in which the liquid includes a silver halide developer and a silver halide solvent which react with unexposed silver halide of the image recording sheet to form a soluble silver complex which diffuses to an image-receptive layer on sheet 40 where it is reduced to metallic silver to form a visible positive image. For further examples of processes and materials of this type, reference may be had to US. Patents Nos. 2,543,181, issued Feb. 27, 1951, and 2,662,822, issued Dec. 15, 1953, both in the name of Edwin H. Land. The apparatus is designed for use in producing prints by diffusion-transfer processes characterized by the fact that no image-forming substances, and this includes dyes and dye intermediates in addition to soluble silver complexes, are formed in or are transferred from exposed areas of the photosensitive image-recording sheet.

The apparatus includes means in the form of a nozzle 48 for dispensing the processing liquid as a layer located between sheets 32 and 40 and extending to the edges of image-recording sheet 32. The liquid is dispensed at the bite of the pressure-applying rolls and means are also provided for holding a supply of the processing liquid, delivering the liquid to the nozzle under pressure and supporting the nozzle in proper position to perform its liquid-dispensing function. Nozzle 48 is preferably formed of material which is impervious to the liquid and to air, and is fiexible and resilient. Various organic plastics and rubber are suited for this purpose and include, for example, high density polyethylene, polypropylene, polyvinylidene chloride, and polyethylene terephthalate resins. The nozzle includes an elongated and generally cylindrical body including a pair of elongated lips extending from end to end of the body and defining therebetween a tapered passage defining an elongated discharge mouth at the edges of the lips substantially equal in length to the width of the image-recording sheet. In operation, nozzle 48 is located with the lips extending toward the bite of the roll between convergent portions of sheets 32 and 40 with the outer surfaces of the edge portions of the lips located in face-to-face contact with the facing surfaces of the sheets. The processing liquid is supplied to the nozzle under presure sufficient to cause the liquid, (which may be quite viscous), to flow through between the lips from which it is dispensed as a layer between the sheets as the sheets move past and in contact with the lips. The movement of the liquid bet-ween the lips together with the pressure exerted on the liquid combine to press the outer surfaces of the lips against the surfaces of the sheets forming a liquid-tight seal between the lips and the sheets which seal also prevents air from entering between the sheets and lips.

The processing liquid is supplied and stored under pressure in a container 66 held in a tube 68 around which sheet 40 is coiled. Tube 68 is provided with flanges 70 at its ends for aligning the convolutions of sheet 40 coiled around the tube. The processing liquid is conducted from container 66 to nozzle 48 through a conduit (not shown) connected with tube 68. For details of the construction and manner of operation of container 66 and the assemblage which it comprises, reference may be had to the copending US. Patent application of Edwin H. Land Ser. No. 169,264, filed Jan. 29, 1962, now abandoned.

Movement of the sheets through the apparatus and between the pressure-applying rolls may be accomplished, for example, by manually engaging portions of the superposed sheets extending from between the rolls through the withdrawal passage 46 and applying tension to the sheets for advancing the sheets. The material comprising the sheets may be opaque to actinic light so that the sheets can be withdrawn directly from between the rolls into the light before processing has advanced to the extent that the image-recording sheet is no longer light sensitive. In the operation of camera an area of imagerecording sheet 32 is positioned for exposure on the support surface of rear wall 20 in alignment with aperture 30, is exposed and is then advanced into superposition with a corresponding area of second sheet 40 between pressure-applying rolls 42 and 44 while the processing liquid is distributed from nozzle 48 in a thin layer between the sheets; and the sandwich thus formed is advanced through passage 46 from the camera until the exposed area has been drawn between the pressure-applying rolls. Movement of the sheets is then discontinued to permit the next succeeding area of the photosensitive sheet to be exposed and the portion of the sandwich comprising the previously exposed area of the imagerecording sheet may be severed from the remainder of the sandwich extending between the pressure-applying rolls. The diameter of roll 44 is preferably quite small as is the diameter of roll 34 and the distance between roll 44 and the edge of the leading end of the area positioned for exposure so that the space between successive exposed areas of sheet 32 can be maintained at a minimum and is preferably equal to twice the width of the borders to be provided at the ends of the prints. The camera includes a mechanism (not shown) for operating the valve between container 66 and nozzle 48 for controlling the flow of the processing liquid from the container to the nozzle and to shift the pressure-applying rolls between operative and nozzle-sealing positions as required to effect spreading of the liquid during movement of the sheets and sealing of the lips when movement of the sheets is discontinued. A number of different mechanisms are available for mounting the pressure-applying rolls and performing these functions, operated for example, by rotation of roll 34; and suitable mechanisms are described in detail in the aforementioned application Ser. No. 169,- 264. Such mechanisms would also include means for automatically arresting the movement of the sheets each time a predetermined length of the image-recording sheet has been advanced through the apparatus.

Employment of an image-recording sheet (as shown) which is equal in width to the transfer image comprising the finished prints results in image-free, well-defined lateral margins on the prints. Other methods and means must be provided for producing the end margins on the prints and for producing lateral margins when the image-recording sheet is wider than the images, and these include completely exposing the photosensitive material of the image-recording sheet in areas thereof corresponding to the borders of the transfer images, i.e., the spaces between the areas of the image-recording sheet which are photographically exposed toproduce images. By complete exposure of the photosensitive material it is meant that the photosensitive material is exposed to an extent that image-forming substances cannot be transferred from the photosensitive material thus exposed, transfer being precluded by the fact that either formation of image-forming substances is made impossible by the exposure or the image-forming substances are immobilized in exposed areas.

The border forming exposure is made, as shown in FIGURE 1, by an exposure means 38 for exposing the space between the image areas of sheet '32 during periods when sheet 32 is at rest with an area thereof in position of exposure. Exposure means 38 may take the form of a low level source of light actinic to the photosensitive material of the image-recording sheet. The level of light emitted by the source may be such that the light emitted is insufficient to fog the photosensitive material during movement of the image-recording sheet past the source, yet of sufficient intensity to cause a complete exposure of the photosensitive material during periods when the image-recording sheet is not in movement. By an exposure .insufiicient to cause fogging, it is meant that the exposure is insul'ficient to produce an image (either visible or latent and developable) in the photosensitive material. The actinic radiation for exposing the photosensitive material may be in either the Visible or invisible Wavelength ranges or may be penetrative radiation emitted by a radioactive source. The sources of such radiation may include radioactive materials capable of producing radiations actinic to the photosensitive material or sources for producing light in the visible wavelength ranges. As a source of light, the cameras may also include means for transmitting environmental light from the outside of the camera housing to the film, electrical means for emitting light, or luminescent materials excited by radioactive materials.

Exposure means 38 is shown in more detail in FIG. 2 as comprising a curved light transmitting window 80 located within chamber 22 adjacent rear wall and coated on its inner surface with a luminescent material excited, for example, by beta-radiation to emit light actinic to the photosensitive material. Window 80 is mounted on a support member 82 formed, for example of metal, to provide a recessed surface spaced fro-m and substantially parallel with the inner surface of the window and cooperating with the window to provide a chamber 84 underlying the window and filled with a radioactive material such as tritium, for exciting the phosphor coating on the inside of the window. The exposure means shown in FIGURE 1 is of the low level type adapted to completely expose the photosensitive material only when the photosensitive material is held stationary with respect to the exposure means.

Since certain changes may be made in the above process without departing from the scope of the invention herein involved, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

What is claimed is: 1. In a method of producing a succession of positive photographic prints comprising image-forming substances formed from unexposed photosensitive material in areas of a photosensitive image-recording sheet and having image-free borders, the steps comprising:

intermittently moving a photosensitive image-recording sheet to locate a succession of spaced areas of said sheet in position for exposure to light from first exposure means capable of forming images in said areas; while said image-recording sheet is motionless, exposing one of said areas to light from said first exposure means to form an image therein, and exposing transverse portions of said image-recording sheet extending from side to side thereof and bordering said one area. to actinic radiation from second exposure means sufliciently to prevent the subsequent transfer of image-forming substances from said portions;

continuously exposing a transverse portion of said image-recording sheet extending from side to side thereof to actinic radiation from said second exposure means at a predetermined intensity level;

and between exposure to light from said first exposure means exposing said spaced areas of said imagerecording sheet upon which an image is formed to said second exposure means while moving said image-recording sheet relative to said second exposure means at a rate so related to said predetermined intensity level that said actinic radiation from said second exposure means is insufficient to produce an image in said areas of said image-recording sheet during movement thereof.

References Cited UNITED STATES PATENTS 2,524,941 10/1950 Taylor -77 2,937,914 5/1950 Blake 95-1.1 X

JOHN M. HORAN, P im ry Examiner.

Claims (1)

1. IN A METHOD OF PRODUCING A SUCCESSION OF POSITIVE PHOTOGRAPHIC PRINTS COMPRISING IMAGE-FORMING SUBSTANCES FORMED FROM UNEXPOSED PHOTOSENSITIVE MATERIAL IN AREAS OF A PHOTOSENSITIVE IMAGE-RECORDING SHEET AND HAVING IMAGE-FREE BORDERS, THE STEPS COMPRISING: INTERMITTENTLY MOVING A PHOTOSENSITIVE IMAGE-RECORDING SHEET TO LOCATE A SUCCESSION OF SPACED AREAS OF SAID SHEET IN POSITION FOR EXPOSURE TO LIGHT FROM FIRST EXPOSURE MEANS CAPABLE OF FORMING IMAGES IN SAID AREAS; WHILE SAID IMAGE-RECORDING SHEET IS MOTIONLESS, EXPOSING ONE OF SAID AREAS TO LIGHT FROM SAID FIRST EXPOSURE MEANS TO FORM AN IMAGE THEREIN, AND EXPOSING TRANSVERSE PORTIONS OF SAID IMAGE-RECORDING SHEET EXTENDING FROM SIDE TO SIDE THEREOF AND BORDENING SAID ONE AREA TO ACTINIC RADIATION FROM SECOND EXPOSURE MEANS SUFFICIENTLY TO PREVENT THE SUBSEQUENT TRANSFER OF IMAGE-FORMING SUBSTANCES FROM SAID PORTIONS; CONTINUOUSLY EXPOSING A TRANSVERSE PORTION OF SAID IMAGE-RECORDING SHEET EXTENDING FROM SIDE TO SIDE THEREOF TO ACTINIC RADIATION FROM SAID SECOND EXPOSURE MEANS AT A PREDETERMINED INTENSITY LEVEL; AND BETWEEN EXPOSURE TO LIGHT FROM SAID FIRST EXPOSURE MEANS EXPOSING SAID SPACED AREAS OF SAID IMAGERECORDING SHEET UPON WHICH AN IMAGE IS FORMED TO SAID SECOND EXPOSURE MEANS WHILE MOVING SAID IMAGE-RECORDING SHEET RELATIVE TO SAID SECOND EXPOSURE MEANS AT A RATE SO RELATED TO SAID PREDETERMINED INTENSITY LEVEL THAT SAID ACTINIC RADIATION FROM SAID SECOND EXPOSURE MEANS IS INSUFFICIENT TO PRODUCE AN IMAGE IN SAID AREAS OF SAID IMAGE-RECORDING SHEET DURING MOVEMENT THEREOF.

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