US 4,055,726 AGranted

Electrical position resolving by zero-crossing delay

OwnerJohn A. Turner, Gordon J. Ritchieinventors

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Abstract

Position responsive apparatus is disclosed comprising a sheet of uniform resistivity having four electrodes in contact therewith around a rectangular area. One pair of parallel electrodes are respectively energized with time-delayed voltage waveforms having linearly increasing portions, and then these voltage waveforms are instead applied to the other pair of parallel electrodes; and this procedure is repeated in sequence. A movable probe makes connection with the resistive layer. The voltage waveform picked off by the probe is found to have a time delay of zero-crossing, measured relative to the zero-crossing of the waveform applied at that time to one of the two electrodes, which is dependent solely upon the position of the probe in the direction perpendicular to that electrode. In this way, the position of the probe within the rectangle defined by the electrodes can be determined.

Claims8

Dependent claims

An electrical position resolver arrangement, comprising

means defining a resistive surface,
at least two electrode means in electrical contact with the surface at points extending respectively along spaced-apart lines,
a movable probe for making electrical connections with the surface at a point between the said lines,
first and second sources respectively providing first and second voltges having substantially similar voltage/time waveforms which are separated by a predetermined time delay and each of which has at least a portion which is unmodulated and substantially linear,
connection means for respectively connecting the first and second voltages to said two electrode means, and
output means responsive to the voltage produced on the probe by the first and second voltages for determining the time delay between the time when the said portion of one of the first and second voltages crosses a datum value and the time when the probe voltage crosses the corresponding datum value, so as to sense the position of the probe relative to the two electrode means to which the first and second voltages are applied.

3 more elements

An electrical position resolver arrangement, comprising

means defining a surface having substantially uniform electrical resistivity,
first and second electrode means making discrete electrical contact with the surface at points respectively extending along two spaced-apart substantially parallel lines,
third and fourth electrode means making discrete electrical contact with the surface at points respectively extending along two spaced-apart substantially parallel lines,
the four said lines being arranged to define a rectangular area on the said surface,
a movable probe for making electrical contact with the surface at a point in the said rectangular area,
first and second voltage sources respectively producing first and second voltages having substantially similar voltage/time waveforms each having a portion which is unmodulated and substantially linear,
first and second switchable connection means for connecting the first and second voltage sources to the first and second electrode means respectively with a predetermined time delay between their waveforms,
third and fourth switchable connection means for connecting the first and second voltage sources to the third and fourth electrode means respectively with the said predetermined time delay between their waveforms,
control means connected to the connection means for switching them between conductive and non-conductive conditions in pairs whereby when the first and second connection means are both conductive the third and fourth connection means are both non-conductive and vice versa, and
output means connected to the probe for sensing the probe voltage and for measuring the time delay between the time when the linear portion of the waveform of the first voltage crosses a datum value and the time when the voltage/time waveform of the probe voltage crosses the corresponding datum value whereby to sense the distance between the instantaneous position of the probe and that one of the electrode means to which the first voltage is at that time applied.

7 more elements

Dependencies are inferred from the claim text.