Patent ID: 6901807

Claim:
In a device for sensing pressure having a sealed chamber defining part, a first perforated film having two sides and mounted on one side in communication with said chamber in said sealed chamber defining part, said first film having a conductive surface, an insulator mounted on said other side of said first film, a second perforated film having two sides and mounted on one side in communication with said insulator, said second film having a conductive surface, a sensor chamber defining part mounted on said other side of said second film and having an opening for communication with a sensing atmosphere, whereby one of said first and second films includes openings it its surface to permit fluid to flow through said openings and said other of said first and second films is solid and responds to change in pressure in said sensor chamber to move away from or toward said one of said flexible diaphragms, and electrical connections contacting said first and said second films and adapted to measure the capacitance between said films as a function of said pressure in said sensor chamber introduced through said opening and causing said one flexible films to move with respect to said other of said films, the improvement comprising: a non-perforated flexible diaphragm mounted between said first and second films and both of said first and second films are perforated, said non-perforated diaphragm being spaced from said first and second films such that said non-perforated diaphragm is adapted to flex toward said first film when pressure increases in said opening and is adapted to flex toward said second film when pressure decreases in said opening to change the capacitance between said non-perforated diaphragm and at least one of said first and second films.