Capacitance weighing mat with substantially rigid separators

PCT No. PCT/CA93/00395 Sec. 371 Date Mar. 21, 1995 Sec. 102(e) Date Mar. 21, 1995 PCT Filed Sep. 23, 1993 PCT Pub. No. WO94/18529 PCT Pub. Date Aug. 18, 1994A capacitance mat for use in measuring loads includes a number of substantially horizontal electrode plates (of high strength aluminum) forming a capacitor with a substantially rigid dielectric material (e.g. nylon or fiberglass) separator disposed between the stacked substantially parallel electrode plates. The separators define spaces at which at least one of the electrode plates may bend in response to an applied load, to move with respect to each other, causing the capacitance of the mat to change. The separators may comprise a number of substantially parallel elongated strips of substantially rigid dielectric material spaced from each other in a dimension transverse to the dimension of elongation to define the spaces. At least first, second and third electrode plates may be provided, with the separator strips between the first and second plates substantially parallel to the strips between the second and third plates and located substantially centrally in the spaces between the strips between the second and third plates. The strips may be about +E,fra 1/32+EE nd of an inch thick and adhesively secured to the plates. Circuitry mounted on the mat detects the changes in capacitance resulting from bending of at least one of the electrode plates.