Inventors:
Dale E. Gandrud - Owatonna MN
Assignee:
Gandy Company - Owatonna MN
International Classification:
H01H 1370
Abstract:
An improved membrane switch (12) of greater sensitivity and simplified, lightweight construction which is particularly adapted for sensing material levels in hoppers, comprises a first non-conductive sheet (18) with conductive open contacts (22), leads (24), and contactor (28) provided on one side thereof. The first sheet (18) is folded back on itself and secured to a spacer or second sheet (20) such that the contacts (22) and contactor (28) are in aligned, normally spaced apart relationship. A second embodiment of the membrane switch (50) comprises four non-conductive sheets (52, 54, 70 and 74) stacked, instead of folded, and interconnected to form a thin yieldable envelope for the normally open contact (62) and contactor (76). In the second embodiment, the third sheet (70) acts as the spacer. In both embodiments, the spacer sheet extends along only one side of the contact and contactor, which are normally urged apart by the resiliency of the non-conductive material provided by the particular construction, but which yield to a closed position under relatively low, generalized pressure.