Photography – Self-developing camera – Including means to treat superimposed material
Reexamination Certificate
2000-02-09
2001-12-04
Rutledge, D. (Department: 2851)
Photography
Self-developing camera
Including means to treat superimposed material
C396S038000
Reexamination Certificate
active
06327431
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to photographic apparatus and film assemblages for use therewith and, more specifically, to improvements regarding methods and apparatus for processing such film units in a photographic apparatus.
Heretofore, the prior art relating to so called instant film technology encompasses film assemblages that are removed manually from cameras of the self-developing type. These film assemblages include two sheets of flexible photographic material and a rupturable reservoir containing processing fluid. The rupturable reservoir includes a weakened portion that ruptures upon the application thereto of predetermined compressive forces that are applied by a pressure applying assembly during film assemblage removal. It is extremely important for the successful development of latent images on the photographic material that the fluid be spread in a layer relatively uniformly throughout the extent of the photosensitive layer. Therefore, a series of parameters have been established whereby the width of the pressure applying area, the viscosity of the processing fluid and the rate at which the sheet materials are withdrawn through a pressure applying nip, the shape of the pressure applying members and the pressure generated ensure that the spreading of the processing fluid occurs at a substantially uniform pre-determined thickness regardless of variations in thickness of the materials, the viscosity of the liquid and the speed of movement of the sheet materials through the pressure applying members. In addition, the pulling of the film along a plane generally perpendicular to the film exit is also desired to maintain the uniform layer. However, there is no control of the direction of tension applied to the sheets and the angular direction by which the film exits the cameras. As a result, it may be that a film assemblage is withdrawn at an angle with respect to a desired pulling plane that includes the bite line of the pressure-applying members. Such angular deviation results in a lack of thickness uniformity of the processing fluid layer that is spread between the sheets and thereby results in image artifacts.
Known attempts to overcome this problem are described in, for example, commonly assigned U.S. Pat. No. 2,845,850 camera having a device that defines a passage or gap that is spaced from the camera's film exit slot. The size of such passage is such that while pressure is not applied on the sheets as they move through the passage, the angular deviation of the sheets from the desired pulling plane is limited. However, sharp bending of the sheets around leading edges or lips of this device is problematic and could result in separation of the two sheets with attendant image artifacts being created in the developed image.
While it is been known to address the problem of non-uniform spreading of processing fluid between superposed sheets of photosensitive material of the self-developing type, it is nevertheless, desired to improve upon heretofore known approaches.
SUMMARY OF THE INVENTION
In accordance with the present invention, provision is made for a method of processing a film assemblage including a pair of juxtaposed photographic sheet materials and a rupturable reservoir of processing fluid. In an illustrated embodiment the method comprises the steps of: providing a photographic apparatus for housing the film assemblage and for allowing the manual withdrawal thereof. Included is a step of applying pressure to rupture the rupturable reservoir in order to dispense the processing fluid between the photographic sheets to thereby initiate development of latent images thereon. The method includes a step of providing film engaging members located exteriorly of an exit slot that are sized and spaced for allowing preselected withdrawal of the film from the exit at preselected angles of angular pitch relative to a generally horizontal exit plane.
In another embodiment of the invention, provision is made for a self-developing camera or photographic apparatus for use with the film assemblage including a pair of juxtaposed photographic sheet elements one of which carries a pod of processing fluid which is rupturable upon application thereto of predetermined compressive forces by a pressure applying means. The camera includes a housing defining an exit slot, which permits manual withdrawal of the film assemblage from the housing. Provision is also made for at least one film engaging member exterior of the exit slot and spaced therefrom by a predetermined amount which ensures that the film may be pulled at a preselected angle of angular pitch with respect to a horizontal plane so that the spreading of the fluid brought about by the pressure applying means is achieved substantially uniformly.
In another illustrated embodiment, provision is made for a second engaging member that extends from the film exit housing in a similar direction as the first engagement member and spaced from the first engaging member.
It is an object of the present invention to provide for improved photographic apparatus and method of processing film of the self-developing type for use in such photographic apparatus that minimizes image artifacts resulting from withdrawing the film from a camera.
It is a further object of the present invention to provide for an improved photographic apparatus and method of the foregoing type wherein the self-developing film assemblage may be manually withdrawn from the slot without diminishing the uniform thickness of the processing fluid layer despite angular pitch changes of the film during withdrawal.
It is another object of the present invention to provide for such a photographic apparatus and method wherein the achievement of the uniform spreading is accomplished through the utilization of film engagement members that selectively engage the film and limit its degree of angular deviancy with respect to a horizontal pull plane.
It is still a further object of the present invention to provide for an improved apparatus and method of foregoing type, which is achieved in a simplified construction.
The above and other objects and scope of the present invention will become apparent following reading a detailed description thereof and taken in conjunction with the accompanying drawings in which like reference numerals designate like structure throughout the several views.
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patent: 5237361 (1993-08-01), Cardoos, Jr. et al.
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patent: 6019525 (2000-02-01), Norris
PCT International Search Report for PCT/ US00/ 03468 (Form PCT/ISA/210).
Gjeltema Paul D.
Parsons Harry R.
Salvo Lawrence J.
Corvea Paul M.
Polaroid Corporation
Rutledge D.
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