Acoustic digitizing system
First Claim
1. An acoustic position sensing apparatus for determining the position of an indicator in relation to a datum surface, said apparatus comprising:
- acoustic point source transmission means on said indicator, for transmitting a sequence of periodic acoustic oscillations;
a plurality of acoustic receivers positioned about said datum surface for receiving said acoustic oscillations;
Comparator means connected to each acoustic receiver for converting said received acoustic oscillations to squared waves having logical up and down levels and step transitions therebetween;
Detection means coupled to each said comparator means for determining from at least a leading portion of a squared wave that said squared wave has resulted from an acoustic oscillation generated by said acoustic point source transmission means, and providing an output upon making such a determination, which is indicative of an occurrence of a step transition of said squared wave; and
means responsive to said outputs from said detection means for finding the position of said indicator.
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Accused Products
Abstract
An acoustic position sensing apparatus is described which determines the position of an indicator in relation to a datum surface or volume. The apparatus comprises an acoustic point source transmission device mounted on the indicator for transmitting a sequence of periodic acoustic oscillations, and a plurality of acoustic point receivers positioned about the datum surface for receiving the acoustic oscillations. Comparators are connected to each acoustic receiver for converting the received acoustic oscillations to squared waves having logical up and down levels. A register or other time determining circuit is coupled to each comparator and receives at least a leading portion of a squared wave and determines that the squared wave has resulted from an acoustic oscillation generated by said acoustic point source transmission device. It provides an output upon making such a determination, which is indicative of an occurrence of a step transition of the squared wave. A processor is responsive to the outputs from the registers to find the position of the indicator. The acoustic point source transmission device is configured both as a linear stylus and as a planar "puck", both having at least a pair of acoustic transmitters. The apparatus employs, for two dimensional position detection, at least three acoustic receivers arranged in a non-linear fashion. A three dimensional position detector system is described which employs four receivers, three of which are oriented in one plane and a fourth in another plane.
171 Citations
19 Claims
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1. An acoustic position sensing apparatus for determining the position of an indicator in relation to a datum surface, said apparatus comprising:
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acoustic point source transmission means on said indicator, for transmitting a sequence of periodic acoustic oscillations; a plurality of acoustic receivers positioned about said datum surface for receiving said acoustic oscillations; Comparator means connected to each acoustic receiver for converting said received acoustic oscillations to squared waves having logical up and down levels and step transitions therebetween; Detection means coupled to each said comparator means for determining from at least a leading portion of a squared wave that said squared wave has resulted from an acoustic oscillation generated by said acoustic point source transmission means, and providing an output upon making such a determination, which is indicative of an occurrence of a step transition of said squared wave; and
means responsive to said outputs from said detection means for finding the position of said indicator. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. An acoustic transmitter comprising:
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a housing having an inner space and an aperture communicating with said inner space, said aperture being sized to approximate a point source for said transmitter; transducer means mounted in said housing for generating, in response to an energizing voltage pulse, ultrasonic acoustic signals which pass through said aperture and create a uniform beam pattern; and means for applying energizing voltage pulses to said transducer means, each said energizing voltage pulse exhibiting a voltage which substantially exceeds the rated continuous voltage for said transducer means, the duration and voltage level of said voltage pulses being selected so as to cause the dissipated power from said transducer means not to exceed said transducer means maximum power rating.
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18. An acoustic position sensing apparatus for determining the position of an indicator in relation to a datum surface, said apparatus including acoustic point source transmission means on said indicator for transmitting a sequence of periodic acoustic oscillations, said transmission means comprising:
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a pair of point source acoustic transducers; means for supporting said transducers in a spaced apart relationship along a common line, said supporting means further having indicator means located on said line, said supporting means further being movable by hand across said datum surface to indicate a point on said surface, said supporting means being substantially planar in shape, and said indicator means being positioned between said transducers. - View Dependent Claims (19)
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Specification