Abstract: An apparatus is disclosed for determining the position of a moveable element over the surface of a solid medium. First and second transducer devices are provided and are moveable for placement at selected respective first and second locations on the surface for coupling with said surface. A third transducer device, for coupling with said surface, is mounted with the moveable element. Ultrasonic energy is transmitted, in either direction, between the third transducer device and the first and second transducer devices, the ultrasonic energy travelling through said solid medium. The transit times of the ultrasonic energy propagating, in either direction, between the third transducer device and the first and second transducer devices are determined, the transit times being indicative of the position of the third transducer device with respect to the first and second transducer devices.

Abstract: The disclosure is directed to a circuit for producing electrical discharges in response to trigger signals, and a form of the disclosure is directed to an apparatus, which includes such a circuit, for determining the transit time of acoustic energy travel between a transmitter location and a receiver location.

Abstract: The disclosure is directed to a method and apparatus for more accurately determining the transit time of acoustic energy travel between a transmitter location and a receiver location. An electrode pair spark gap is provided at the transmitter location, and an acoustic receiver is provided at the receiver location. The spark-gap is energized to produce a spark by coupling an electrical potential across the electrode pair. The generation of a spark at the spark gap is sensed, and an initializing signal is generated in response thereto. A timer is initialized in response to the initializing signal. The receipt of acoustic energy from the spark is detected at the receiver location and a terminating signal is generated in response thereto. The timer is terminated in response to the terminating signal, and the time measured by the timer is indicative of the transit time of acoustic energy travel between the transmitter and receiver locations.

Abstract: An apparatus and method for determining the position of a movable element. An elongated housing is provided for positioning generally adjacent an edge of an area in which the position of the movable element is to be determined. The housing has a base portion which contains a pair of spaced-apart transducers that are mounted in the surface of the base portion and face the area. An upper body portion of the housing is disposed above the base portion and protrudes in cantilevered fashion toward the area, so that the transducers are recessed from the area beneath the protruding upper body portion of the housing. Circuitry is provided for determining the position of the movable element from the respective transit times of energy propagating in either direction between the movable element and the pair of transducers.

Abstract: The disclosure is directed to an apparatus and method for determining the travel time of acoustic energy over an unknown travel distance between an acoustic transmitter and an acoustic receiver. This information can be used, for example, to determine the position of a moveable element in a data space. A timer is initiated at the time of acoustic transmission from the transmitter. A control signal generator is provided, and is initiated at the time of acoustic transmission from the transmitter, the control signal being a function of the time which elapses after the time of acoustic transmission. The gain of the signal received at the receiver is controlled in accordance with the control signal. The timer is terminated when the gain-controlled received signal exceeds a predetermined threshold. In a preferred embodiment, the terminating means includes a comparator for comparing the gain-controlled received signal to the predetermined threshold.

Abstract: A form of the disclosed invention employs data validation and screening based on the proximity of sequentially measured data points. Another form of the invention detects noisy conditions manifested in a pilot signal measurement, and discards data taken just after (and/or, if desired, just before) detection of the condition.

Abstract: An apparatus is disclosed for digitizing positions on a transparency. The apparatus includes a cool light box and an acoustic digitizer.

Abstract: An apparatus is disclosed for determining the position of a moveable element in a three-dimensional workspace near a mounting surface. A sound source is provided in the moveable element. A plurality of at least three housing units are adapted to be secured to said mounting surface in spaced relationship to one another. A sound sensor is mounted on each of the units, and a sound source is mounted on at least some of the units. The positions of the sound sensor and the sound source of said at least some of the units can be adjusted. Means are provided which are responsive to the sound from the sound source of at least one of the units and received at the sound sensor of another of the units, for computing the distance between the sound source of said one of the units and the sound sensor of said another of said units.

Abstract: An improved stylus is disclosed for generating acoustic wave energy for use in an acoustic digitizer system wherein an operator-designated stylus position is determined from measurements performed on acoustic energy generated at the stylus. A stylus body is provided and has a generally elongated shape. A tip member extends from the front of the stylus body, the tip member preferably being elongated and narrowing to a point at its front end. A pair of spaced conductive wires are disposed in said tip member, the wires preferably being substantially parallel and having their front ends terminating forwardly in the tip member. The wires extend rearwardly in the tip member, and means are provided for coupling the wires to a source of electrical potential. In the preferred embodiment, the tip member is tubular, and the front ends of the wire pair terminate in the tubular bore of the tip member at a position where the tip member begins to narrow to a point.

Abstract: The invention is applicable for use in conjunction with hand-held calculators, preferably of the type having a substantial computing and programming capability. The calculator typically has a housing, an input keyboard on the housing, a computing module in the housing which includes input terminals coupled to the keys of the keyboard, and a display coupled to the output of the computing module. In accordance with the invention, there is provided an interface for entering numeric information from a companion device, such as a graphical digitizer, into the computing module of the hand-held calculator. The interface includes a multipin connector element affixed to the housing of the calculator and a plurality of conductors for coupling the pins of the connector element to the input terminals of the computing module, these conductors being connected in parallel with the inputs from the keyboard.