Abstract: A method of operating a contact sensor and a method of calibration of a contact sensor. The contact sensor comprises an array of discrete and spaced apart sensing elements (102, 202) connected to a resistive element (101, 201) with the location or size of a contact being detectable by measurement of one or more electrical parameter(s) relating to impedance steps along the resistive element (101, 201) is described. The method of operating involves determining a length of the sensing element between the contact and the resistive element and using this to compensate for a parasitic resistance present in the measured resistance of the resistive element.

Abstract: A contact sensor apparatus comprises: a first insulative layer (100); a second insulative layer (200); a first resistor strip (101) on the first insulative layer; a second resistor strip (201) on the second insulative layer; a plurality of first conductive traces (102) provided on the first insulative layer and electrically connected to the first resistor strip; and a plurality of second conductive traces (202) provided on the second insulative layer and electrically connected to the second resistor strip. The first insulative layer and second insulative layer face each other such that the plurality of first conductive traces face the plurality of second conductive traces with each of the first conductive traces extending across the plurality of second conductive traces and each of the second conductive traces extending across the plurality of first conductive traces thereby forming an array of points of intersection of the first and second conductive traces.

Abstract: A method of detecting a contact 300 using a contact sensor having an array of discrete and spaced apart sensing elements 102, 202 comprises: measuring the value of a parameter and, when the measured value of the parameter varies between a first value and a second value with the variation being indicative of a partial and/or intermittent contact with an adjacent sensor element, determining an estimated value for the parameter intermediate the first value and the second value.