X-ray film holder using capacitive sensing for determining film size
AssigneeMinnesota Mining and Manufacturing Company
InventorLeverne Kisrow
Life of this patent
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Abstract
An X-ray film holder wherein a number of capacitive sensors are positioned and connect with circuitry for determining the presence of film in the holder and, when film is present, determining which one of several predetermined sizes have been placed in the film holder, plus whether the film is properly centered with such information used to provide control signals including a signal with a characteristic dependent on the width dimension of the film and a signal with a characteristic dependent on the length dimension. In addition, the circuitry provides a visible indication of the length dimension of the film placed in the holder for use in positioning the holder with respect to the X-ray source.
Claims10
An improved X-ray film holder of the type for use with any one of a plurality of different predetermined film sizes, the holder having an open-topped receptacle which is closed by a top plate, and a pressure plate positioned in the receptacle wherein a vacuum when formed within the film holder draws the top plate of the holder toward the pressure plate to tightly sandwich a film positioned between the top plate and pressure plate, the improvement including
- a plurality of capacitor structures, each having two plates, one plate positioned for movement with said top plate and the other positioned at said pressure plate, said capacitor structures positioned to receive or not receive a film between the plates dependent on which one of the predetermined film sizes is positioned in the film holder;
- circuitry positioned within the holder and connected to said capacitor structures, said circuitry including an oscillator connected to said capacitors, a plurality of differential amplifiers connected to said capacitors for providing signals dependent on the oscillator signal passed by the capacitors as determined by the presence or absence of film at the various ones of said plurality of capacitor structures;
- decoding logic having a width dimension output for each possible film width dimension and a length dimension output for each possible film length dimension, said decoding logic operatively connected to said differential amplifiers and responsive thereto for providing a signal at one of said width and one of said length dimension outputs of said decoding logic corresponding to the film size presented to the holder, circuit means connected to said width dimension outputs of said decoding logic for providing a signal having a characteristic determined by the width dimension output of said decoding logic at which a signal is provided and circuit means connected to said length dimension outputs of said decoding logic for providing a signal having a characteristic determined by the length dimension output of said decoding logic at which a signal is provided.
An X-ray film holder of the type for use with any one of a plurality of different predetermined film sizes including
- capacitive responsive means positioned within the holder having a width dimension output for each possible film width dimension and a length dimension output for each possible film length dimension, said capacitive responsive means responding to a film presented to the holder for providing a signal at the width dimension output corresponding to the width dimension of the film and a signal at the length dimension output corresponding to the length dimension of the film;
- and
- circuit means connected to said width and length dimension outputs, said circuit means providing a first signal having a characteristic determined by said width dimension output at which a signal is presented and providing a second signal having a characteristic determined by said length dimension output at which a signal is present.
An X-ray film holder of the type for use with any one of a plurality of different predetermined film sizes, wherein proper use of such film requires that it be centered in the holder including a first and second set of capacitive structures positioned within the holder, each set having a plurality of capacitive structures;
- and circuitry including
- 1. an oscillator connected to said capacitive structures;
- 2. a first set of circuits, each connected to two of said capacitive structures in said first set;
- 3. a second set of circuits, each connected to two of said capacitive structures in said second set, each of said first and second sets of circuits providing a signal when only one of said capacitor structures connected to it has film presented to it;
- 4. a first logic circuit having a width dimension output for each possible film width dimension and a length dimension output for each possible film length dimension, said first logic circuit operatively connected to the first set of circuits and responsive thereto for providing a signal at one of said width and one of said length dimension outputs corresponding to the film size presented to the holder;
- 5. a second logic circuit operatively connected to said first set of circuits and to said second set of circuits for providing a signal when the film placed in the film holder is properly centered, and
- 6. a first and second circuit means, each connected to said second logic circuit for receiving said signal provided by said second logic circuit, said first circuit means connected to said width dimension outputs of said first logic circuit for providing a signal having a characteristic determined by the width dimension output of said first logic circuit at which a signal is provided coincident with said signal from said second logic circuit and said second circuit means connected to said length dimension outputs of said first logic circuit for providing a signal having a characteristic determined by the length dimension output of said first logic circuit at which a signal is provided coincident with said signal from said second logic circuit.
Dependencies are inferred from the claim text.