Card – picture – or sign exhibiting – Photographic transparency viewer – e.g. – x-ray viewer
Patent
1997-12-17
2000-09-19
Green, Brian K.
Card, picture, or sign exhibiting
Photographic transparency viewer, e.g., x-ray viewer
40448, 345 87, G02B 2702
Patent
active
061193801
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates generally to a transparencies viewing device and, more particularly, to apparatus for holding and illuminating X-ray transparencies and the like.
BACKGROUND OF THE INVENTION
Medical X-ray transparencies are usually examined by placing them over the viewing surface of a device commonly referred to as an illuminator. Conventional illuminators normally comprise a box-like structure enclosing fluorescent lighting tubes behind a light diffusing plate defining the display area. Commonly, transparencies are retained on the surface of the viewing surface by pushing the upper edge of the transparencies under spring-loaded film-holder clips located along the top edge of the viewing surface.
Standard size illuminators have a viewing surface 17 inches high and 14 inches or multiples of 14 inches (i.e. 28 inches or 56 inches) wide. Usually, each 14 inch width of viewing surface has its own fluorescent tubes and control switch. Such viewing surface enables the viewing of standard size X-ray films which measure up to 17 inches by 14 inches.
The sections of the viewing surface not covered by transparencies need not be illuminated. This eliminates unnecessary glare from areas outside the transparency. When transparencies smaller than 14 inches by 17 inches are to be examined, they are typically retained on the display area in the same manner as full size transparencies, i.e., suspending them by means of the film-holders along the top of the viewer. This leaves a portion of the display area surrounding the transparencies fully illuminated, with the resulting glare detracting from the visual perception of the person trying to study the transparency and assess the information it contains.
Moreover, in many instances, the region of the display area which is of highest interest to the viewer is quite dense. Thus, viewing of the region and assessment of information therefrom may be particularly cumbersome and difficult.
Often transparencies contain several very transparent areas, and, frequently, radiologists have to examine over-exposed transparencies. In these cases, considerable glare emanates through areas of the transparencies themselves.
Attempts have been made in the past to provide viewing devices for X-ray transparencies which shield the eyes of the observer from light other than that passing through the transparencies; to obscure light in parts of the transparencies, and to reduce the contrast in transparencies when so required.
U.S. Pat. No. 1,988,654 to Haag discloses a light box which incorporates two manually movable curtains for masking all of the light-transmitting surfaces of a diffuser up to the edges of a transparency.
U.S. Pat. No. 2,436,162 to Cadenas discloses an X-ray viewer having a masking arrangement incorporating a plurality of hinge-connected opaque masks which may be manually pivoted relative to each other to expose all or only selected parts of an X-ray transparency.
U.S. Pat. No. 4,004,360 to Hammond is directed to a self-masking viewing device which purports to automatically obscure areas of the viewing screen not occupied by the X-ray transparency. In the disclosed device, the screen is provided with a multiplicity of holes which may be selectively blocked by shutters or opened for the passage of light. The interior of the device is connected to a vacuum source which functions to hold the film against the front surface of the device.
The vacuum functions, in addition, to close the shutters connected with those holes not covered by the transparencies, so that passage of light through such holes is prevented. Air cannot pass through those holes in registry with the transparencies and, thus, the shutters associated with the covered holes remain open for the passage of light. The device described is unsuitable for critical inspection of X-ray transparencies since the presence of holes and shutters in the areas in registry with the transparencies creates a pattern behind the transparencies which interferes with the ability to accurately read the
REFERENCES:
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Green Brian K.
SmartLight Ltd.
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