Patent attributes
A pressure-responsive seat occupancy sensor unit (10) for detecting an occupancy state of a seat comprises a support plate (12) with a support area (14), a pressure-responsive membrane switch (15), one or more spacers (16) arranged around the support area and a compressible foam. The membrane switch comprises a first carrier film and a second carrier film spaced from each other by a spacer film. The spacer film has therein an opening defining a cell. The membrane switch comprises at least two electrodes arranged in facing relationship with each other in the cell on the first and the second carrier film, respectively, in such a way that they are brought closer together, possibly into contact with each other, when sufficient pressure is applied on the membrane switch. The one or more spacers (16) protrude from the support, and define an upper surface (20) raised with respect to the support area. The compressible foam (18) rests with its bottom surface (22) on the upper surface of the one or more spacers. The compressible foam penetrates into the support area in between the one or more spacers and activates the pressure-responsive membrane switch in response to a force applied on the top surface that exceeds a certain threshold force.
