Capacitive pressure transducer

In a pressure responsive capacitive transducer in which a reference plate bearing an electrode is mounted on the deformable portion of a diaphragm having a substantially coextensive electrode, the improvement comprising:

• a conductive spacer centrally disposed on the deformable portion of the diaphragm and coupled to both the reference plate and the diaphragm, the spacer comprising a conductive element having a height of less than 2 mils and a width of less than about 25% of the diameter of the deformable portion of the diaphragm;
• means providing an electrical signal conductor on the diaphragm;
• and
• means coupling the electrode on the reference plate to the electrical signal conductor through the spacer.

A capacitive pressure transducer comprising:

• a diaphragm having a substantially flat deformable surface, the diaphragm including a sensor electrode disposed about a central region thereof, and a reference electrode substantially encompassing the sensor electrode;
• means coupled to at least one side of the diaphragm for providing a fluid, whose pressure is to be measured into contact with the diaphragm to deform the same;
• a substantially planar reference plate disposed in facing relation to the deformable surface of the diaphragm and including a sensor electrode disposed about the central region and in opposition to the sensor electrode on the diaphragm to form a sensing capacitor therewith;
• spacer means disposed in the central region and between the diaphragm and the reference plate to maintain a substantially fixed dimension in the central region therebetween while permitting deformation of the diaphragm;
• and
• cover means disposed about the reference plate and coupled to the periphery of the diaphragm and including a reference electrode in facing relation to the reference electrode on the diaphragm to form a reference capacitor therewith.

A capacitive pressure transducer comprising:

• a diaphragm having a substantially flat deformable surface, the diaphragm including an annular sensor electrode disposed about a central deformable region thereof concentric with a central axis, an annular reference electrode, said electrodes each terminating in a conductive contact path to the exterior, an electrically grounded guard electrode and positioned between said sensor electrode and said reference electrode, said sensor electrode, said reference electrode, and said guard electrode being concentric about the central axis, and said diaphragm further including thin film conductive means in the central region of said diaphragm including a conductive path to the exterior of the transducer;
• means communicating with at least one side of the diaphragm for introducing a fluid whose pressure is to be determined into contact with the diaphragm to deform same;
• a substantially planar reference plate disposed in facing relation to the deformable surface of the diaphragm, said reference plate having an annular sensor electrode disposed about the central region and facing the sensor electrode on the diaphragm to form a sensing capacitor therewith, and thin film conductive means in the central region of said reference plate, including a conductive path to said sensor electrode on said reference plate;
• conductive spacer means interconnecting the diaphragm and the reference plate in the central region thereof to maintain a substantially fixed dimension in the central region between the diaphragm and the reference plate while permitting deformation of the diaphragm, said spacer means interconnecting the thin film conductive means on said diaphragm with the thin film conductive means on the reference plate, whereby an electrical connection from the sensor electrode on the reference plate is taken through the spacer means;
• and
• a cover disposed about the reference plate, said cover comprising a depending flange connected to the outer periphery of the diaphragm, and including an annular reference electrode in facing relation to the reference electrode on the diaphragm, to form a reference capacitor therebetween, said reference electrode on said cover terminating in a conductive path to the exterior.

A capacitive pressure transducer comprising:

• a diaphragm having a central web deflectable in response to a pressurized fluid acting against a first side thereof, the diaphragm including a peripheral flange;
• a cover adjacent the second side of the diaphragm and coupled thereto at the peripheral flange;
• reference capacitor means disposed between the diaphragm and cover in the peripheral flange region;
• reference plate means mounted on the second side of the central web and movable with deflection thereof;
• and
• sensing capacitor means disposed between the second side of the diaphragm and the reference plate means.

A capacitive pressure transducer comprising a diaphragm having a peripheral flange bounding a central deflectable web that deflects in response to a pressurized fluid acting on a first side thereof, without substantial deflection of the flange;

• cover means adjacent the second side of the diaphragm and coupled thereto at the peripheral flange;
• plate means mounted on but principally spaced apart from the second side of the diaphragm at the web and movable therewith;
• first capacitor means responsive to the distance between the web and the plate means;
• and
• second capacitor means responsive to the distance between the flange and the cover means.

A pressure responsive capacitive transducer comprising:

• a diaphragm having a deformable central region responsive to pressure applied to one side thereof, the diaphragm including a thin film electrode thereon;
• a planar element disposed adjacent but spaced apart from the deformable central region of the diaphragm and including a thin film electrode in facing relation to the thin film electrode on the diaphragm;
• and
• conductive spacer means disposed in the maximum deflection portion of the deformable central region of the diaphragm for (1) mechanically coupling the planar element to move with the deformable central region of the diaphragm and (2) providing electrical coupling to the thin film electrode on the diaphragm.