Absolute capacitance manometers
First Claim
1. Capacitive pressure transducer apparatus having a diaphragm in fluid-tight separating relation to regions exhibiting different fluid pressure conditions, said diaphragm including electrically-conductive capacitor electrode surfaces movable therewith, and composite capacitor means disposed in one of said regions, said composite capacitor means including a flexible member having electrically-conductive capacitor electrode surfaces movable therewith in closely-spaced relation to said electrode surfaces of said diaphragm and forming a first variable capacitor therewith, and a relatively rigid member mounting relatively stationary electrically-conductive capacitor electrode surfaces in spaced relation to said electrode surfaces of said flexible member and forming a second variable capacitor therewith, and means mounting said composite capacitor means in position relative to said diaphragm for said diaphragm to physically deflect said flexible member in response to and by amounts related to differences in pressures between said regions beyond a predetermined range, whereby said first variable capacitor exhibits cpacitances related to said differences in pressures within said predetermined range and said second variable capacitor exhibits capacitances related to differences in pressures beyond said range.
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Accused Products
Abstract
A single fluid-pressure transducer unit, of the type in which sensed electrical capacitance is varied in accordance with electrode deflections induced by pressure changes, is rendered capable of characterizing a wide range of pressures extending from near-vacuum to atmospheric levels, with the aid of a distinctive composite-electrode capsule which interacts uniquely with a conventional type of sheet-metal diaphragm. While sensing relatively low pressures, the exhibited capacitance of the transducer is essentially that appearing between the diaphragm and a nearby electrode carried by the capsule, but, at or near atmospheric pressure, the diaphragm physically engages and deflects that electrode, which is elastically deformable, causing it to vary a further capacitance appearing between that deformable electrode and a companion stationary electrode which is also part of the capsule.
100 Citations
16 Claims
- 1. Capacitive pressure transducer apparatus having a diaphragm in fluid-tight separating relation to regions exhibiting different fluid pressure conditions, said diaphragm including electrically-conductive capacitor electrode surfaces movable therewith, and composite capacitor means disposed in one of said regions, said composite capacitor means including a flexible member having electrically-conductive capacitor electrode surfaces movable therewith in closely-spaced relation to said electrode surfaces of said diaphragm and forming a first variable capacitor therewith, and a relatively rigid member mounting relatively stationary electrically-conductive capacitor electrode surfaces in spaced relation to said electrode surfaces of said flexible member and forming a second variable capacitor therewith, and means mounting said composite capacitor means in position relative to said diaphragm for said diaphragm to physically deflect said flexible member in response to and by amounts related to differences in pressures between said regions beyond a predetermined range, whereby said first variable capacitor exhibits cpacitances related to said differences in pressures within said predetermined range and said second variable capacitor exhibits capacitances related to differences in pressures beyond said range.
- 15. A method for capacitively characterizing pressures over a wide range which comprises subjecting opposite sides of a diaphragm to pressures appearing in different regions sealed apart by the diaphragm and thereby causing related deflections thereof, establishing a first variable capacitance between first capacitor electrode surfaces movable with the diaphragm and second capacitor electrode surfaces carried by a flexible insulating member in one of said regions, and establishing a second variable capacitance between the second capacitor electrode surfaces and third capacitor electrode surfaces while holding said third electrode surfaces fixedly in position in the said one of said regions, said step of establishing the second variable capacitance involving physically deflecting the flexible insulating member in accordance with deflections of the diaphragm when the diaphragm deflections exceed a predetermined amount.
Specification