Radiation imagery chemistry: process – composition – or product th – Radiation sensitive product – Identified backing or protective layer containing
Reexamination Certificate
1998-09-17
2001-03-13
Hess, Bruce H. (Department: 1774)
Radiation imagery chemistry: process, composition, or product th
Radiation sensitive product
Identified backing or protective layer containing
C428S195100, C428S315900, C428S910000, C428S315500
Reexamination Certificate
active
06200740
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to photographic materials. In a preferred form it relates to base materials for photographic transmission display.
BACKGROUND OF THE INVENTION
It is known in the art that photographic display materials are utilized for advertising, as well as decorative displays of photographic images. Since these display materials are used in advertising, the image quality of the display material is critical in expressing the quality message of the product or service being advertised. Further, a photographic display image needs to be high impact, as it attempts to draw consumer attention to the display material and the desired message being conveyed. Typical applications for display material include product and service advertising in public places such as airports, buses and sports stadiums, movie posters, and fine art photography. The desired attributes of a quality, high impact photographic display material are a slight blue density minimum, durability, sharpness, and flatness. Cost is also important, as display materials tend to be expensive compared with alternative display material technology, mainly lithographic images on paper. For display materials, traditional color paper is undesirable, as it suffers from a lack of durability for the handling, photo processing, and display of large format images.
In the formation of color paper it is known that the base paper has applied thereto a layer of polymer, typically polyethylene. This layer serves to provide waterproofing to the paper, as well as providing a smooth surface on which the photosensitive layers are formed. The formation of a suitably smooth surface is difficult, requiring great care and expense to ensure proper laydown and cooling of the polyethylene layers. The formation of a suitably smooth surface would also improve image quality, as the display material would have more apparent blackness as the reflective properties of the improved base are more specular than the prior materials. As the whites are whiter and the blacks are blacker, there is more range in between and, therefore, contrast is enhanced. It would be desirable if a more reliable and improved surface could be formed at less expense.
Prior art photographic reflective papers comprise a melt extruded polyethylene layer which also serves as a carrier layer for optical brightener and other whitener materials, as well as tint materials. It would be desirable if the optical brightener, whitener materials, and tints, rather than being dispersed a single melt extruded layer of polyethylene, could be concentrated nearer the surface where they would be more effective optically.
Prior art photographic transmission display materials with incorporated diffusers have light sensitive silver halide emulsions coated directly onto a gelatin coated clear polyester sheet. Incorporated diffusers are necessary to diffuse the light source used to backlight transmission display materials. Without a diffuser, the light source would reduce the quality of the image. Typically, white pigments are coated in the bottommost layer of the imaging layers. Since light sensitive silver halide emulsions tend to be yellow because of the gelatin used as a binder for photographic emulsions, minimum density areas of a developed image will tend to appear yellow. A yellow white reduces the commercial value of a transmission display material because the imaging viewing public associates image quality with a white white. It would be desirable if a transmission display material with an incorporated diffuser could have a more blue white, since a white that is slightly blue is preceptually preferred as the whitest white by consumers.
Prior art photographic transmission display materials with incorporated diffusers have light sensitive silver halide emulsions coated directly onto a gelatin subbed clear polyester sheet. TiO
2
is added to the bottommost layer of the imaging layers to diffuse light so well that individual elements of the illuminating bulbs utilized are not visible to the observer of the displayed image. However, coating TiO
2
in the imaging layer causes manufacturing problems such as increased coating coverage, which requires more coating machine drying and a reduction in coating machine productivity as the TiO
2
requires additional cleaning of coating machine. Further, as higher amounts of TiO
2
are used to diffuse high intensity backlighting systems, the TiO
2
coated in the bottommost imaging layer causes unacceptable light scattering, reducing the quality of the transmission image. It would be desirable to eliminate the TiO
2
from the image layers while providing the necessary transmission properties and image quality properties.
Prior art photographic display materials use polyester as a base for the support. Typically the polyester support is from 150 to 250 &mgr;m thick to provide the required stiffness. A thinner base material would be lower in cost and allow for roll handling efficiency, as the rolls would weigh less and be smaller in diameter. It would be desirable to use a base material that had the required stiffness but was thinner to reduce cost and improve roll handling efficiency.
PROBLEM TO BE SOLVED BY THE INVENTION
There is a need for transmission display materials that provide improved transmission of light while, at the same time, more efficiently diffusing in the light such that the elements of the light source are not apparent to the viewer.
SUMMARY OF THE INVENTION
It is an object of the invention to provide improved transmission display materials.
It is another object to provide display materials that are lower in cost, as well as providing sharp durable images.
It is a further object to provide more efficient use of the light used to illuminate transmission display materials.
These and other objects of the invention are accomplished by a photographic element comprising a transparent polymer sheet, at least one layer of biaxially oriented polyolefin sheet, and at least one image layer wherein said polymer sheet has a stiffness in any direction of between 20 and 100 millinewtons, and said biaxially oriented polyolefin sheet has a spectral transmission of at least 40% and a reflection density less than 60%.
ADVANTAGEOUS EFFECT OF THE INVENTION
The invention provides brighter images by allowing more efficient diffusion of light used to illuminate display materials.
DETAILED DESCRIPTION OF THE INVENTION
The invention has numerous advantages over prior transmission display materials and methods of imaging transmission display materials. The display materials of the invention provide very efficient diffusing of light while allowing the transmission of a high percentage of the light. The materials are low in cost, as the transparent polymer material sheet is thinner than in prior products. They are also lower in cost as less gelatin is utilized as no antihalation layer is necessary. The formation of transmission display materials requires a display material that diffuses light so well that individual elements of the illuminating bulbs utilized are not visible to the observer of the displayed image. On the other hand, it is necessary that light be transmitted efficiently to brightly illuminate the display image. The invention allows a greater amount of illuminating light to actually be utilized as display illumination, while at the same time very effectively diffusing the light sources such that they are not apparent to the observer. The display material of the invention will appear whiter to the observer than prior art materials which have a tendency to appear somewhat yellow, as they require a high amount of light scattering pigments to prevent the viewing of individual light sources. These high concentrations of pigments appear yellow to the observer and result in an image that is darker than desirable. These and other advantages will be apparent from the detailed description below.
The terms as used herein, “top”, “upper”, “emulsion side”, and “face” mean the side or toward the side of the photographic member bearing the imagin
Aylward Peter T.
Bourdelais Robert P.
Camp Alphonse D.
Eastman Kodak Company
Hess Bruce H.
Leipold Paul A.
Shewareged B.
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