# US 6,718,827 B1 · Center-mount capacitive sensor with overload protection > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 6,718,827 B1 - Document ID: US6718827B1 - Status: Granted - Kind: B1 - Application number: 10/298,102 - Filed: 2002-11-15 - Granted: 2004-04-13 - Earliest claimed: 2002-11-15 - Assignees: Setray Systems, Inc. - Inventors: Shih-Ying Lee; Gino A. Pinto; Thomas Foley - Web page: https://patentgrep.com/patent/US6718827B1 ## CPC - G01L 9/0072: {using variations in capacitance} - G01L 19/0618: {Overload protection} - G01L: MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE (weighing G01G) ## Abstract A capacitive sensor includes an elastic member extending about a central axis, having a central region, a peripheral region, a first side, and a second side. An overpressure stop member has an inner surface and an outer surface. The inner surface of the overpressure stop member has a contour adapted to limit deflection of the elastic member caused by a differential pressure between the two regions across the elastic member. The outer surface of the overpressure stop member has an first electrically conductive region. A second plate is spaced apart from the outer surface of the overpressure stop member, and being connected to the central region of the elastic member by a post, wherein the post transfers deformation of the elastic member caused by differential pressure across the elastic member to movement of the second plate along the central axis. The second plate has a second electrically conductive region opposite the first electrically conductive region, wherein the first electrically conductive region and the second electrically conductive region form a capacitor. ## Claims ### Claim 1 A capacitive sensor comprising: A. an elastic member disposed about a central axis of said sensor, said elastic member having a central region, a peripheral region, a first side, and a second side; B. a support member supporting the peripheral region of said elastic member; C. an overpressure stop member rigidly coupled to said support member, said overpressure stop member extending over said elastic member except for an aperture region, and having an inner surface and outer surface, said inner surface facing said elastic member; D. a first plate rigidly coupled to said support member and extending over said elastic member except for an aperture region, and having a first surface including a first electrically conductive region thereon; E. a post affixed to and extending from said second side of said elastic member along said central axis, said post passing through said aperture regions; and F. a second plate extending from said post transverse to said central axis, said second plate having a second electrically conductive region opposite said first electrically conductive region of said first surface of said first plate, wherein said opposite electrically conductive regions are electrically insulated from each other. ### Claim 2 (depends on 1) A capacitive sensor according to claim 1 further comprising a boss extending from said central region of said elastic member along said central axis. ### Claim 3 (depends on 1) A sensor according to claim 1, wherein said overpressure stop member and said first plate form an integral structure wherein said outer surface of said overpressure stop member and said first surface of said first plate are coincident. ### Claim 4 (depends on 1) A sensor according to claim 1, wherein said capacitive sensor further comprises an electrically conductive path being provided from a first electrode, via said post, said elastic member, said overpressure stop member, and said first plate, to said first electrically conductive region, a second electrode being connected to said second electrically conductive region, said first and second electrodes being used to indicate the changes in capacitance caused by relative motion of said first and second electrically conductive regions due to pressure differential induced motion of said elastic member. ### Claim 5 (depends on 1) A sensor according to claim 1, wherein said inner surface of said overpressure stop member has a contour adapted to limit deflection of said central region of said elastic member caused by a differential pressure across said elastic member. ### Claim 6 (depends on 1) A capacitive sensor according to claim 1, wherein said inner surface of said overpressure stop member defines a support contour which substantially conforms to a configuration defined by said elastic member when said elastic member deflected to a predetermined extent. ### Claim 7 (depends on 1) A sensor according to claim 1, wherein said pressure differential derives from a pressure being in contact with said first side of said elastic member and a constant, controlled environment being in contact with said second side of said elastic member. ### Claim 8 (depends on 1) A capacitive sensor according to claim 1, wherein said elastic member is an elastic diaphragm. ### Claim 9 (depends on 1) A capacitive sensor according to claim 1, wherein said elastic member is an elastic plate. ### Claim 10 (depends on 1) A capacitive sensor according to claim 1, wherein said elastic member is an elastic beam. ### Claim 11 (depends on 1) A capacitive sensor according to claim 1, wherein said elastic member is made from a material selected from a group of steel, stainless steel, ceramic and glass. ### Claim 12 (depends on 1) A capacitive sensor according to claim 1, wherein said overpressure stop member is made of a substantially rigid material. ### Claim 13 (depends on 1) A capacitive sensor according to claim 1, wherein said elastic member is substantially flat. ### Claim 14 (depends on 1) A capacitive sensor according to claim 1, wherein said elastic member is dome-shaped. ### Claim 15 (depends on 1) A capacitive sensor according to claim 1, wherein said inner surface of said overpressure stop member is substantially planar. ### Claim 16 (depends on 1) A capacitive sensor according to claim 1, wherein said inner surface of said overpressure stop member is concave. ### Claim 17 (depends on 16) A capacitive sensor according to claim 16, wherein said inner surface of said overpressure stop member is contoured such that said inner surface of said overpressure stop member fully and uniformly supports said elastic member when said elastic member deflected to a predetermined extent. ### Claim 18 (depends on 1) A capacitive sensor according to claim 1, wherein said outer surface of said overpressure stop member is substantially planar. ### Claim 19 (depends on 1) A sensor according to claim 1, wherein said capacitive sensor further comprises an electrode assembly including a first electrode electrically coupled to said first electrically coupled region, and a second electrode electrically coupled to said second electrically conductive region. ### Claim 20 A capacitive sensor comprising: A. an elastic member extending about a central axis, said elastic member having a central region, a peripheral region, a first side, and a second side; B. a support member supporting the peripheral region of said elastic member; C. an overpressure stop member coupled to said peripheral region of said elastic member, said overpressure stop member having an inner surface and an outer surface, said inner surface of said overpressure stop member facing said second side of said elastic member and being spaced apart from said central region of said elastic member by a predetermined distance; D. a first plate coupled to said support member, said first plate having a first surface comprising a first electrically conductive region thereon; and E. a second plate spaced apart from and being substantially parallel to said first plate, said second plate being connected to said central region of said elastic member by a post, wherein said post transfers deformation of said central region of said elastic member caused by differential pressure across said elastic member to movement of said second plate along said central axis, said second plate having a second electrically conductive region opposite said first electrically conductive region, wherein said first electrically conductive region and said second electrically conductive region form a capacitor. ### Claim 21 (depends on 20) A capacitive sensor according to claim 20 further comprising an electrode assembly being electrically connected to said first electrically conductive region and said second electrically conductive region, said electrode assembly being adapted for indicating pressure differential derived from a pressure being in contact with said first side of said elastic member and a constant, controlled environment pressure being in contact with said second side of said elastic member. ### Claim 22 (depends on 20) A capacitive sensor according to claim 20, wherein said post is connected to a central point of said elastic member and is adapted for transferring the deformation of said central point to the movement of said second plate. ### Claim 23 (depends on 20) A capacitive sensor according to claim 20 further comprising an electrically conductive path extending from said post to said first electrically conductive region, said electrically conductive path being insulated from said second electrically conductive region. ### Claim 24 (depends on 20) A capacitive sensor according to claim 20, wherein said overpressure stop member and said first plate form an integral structure wherein said outer surface of said overpressure stop member and said first surface of said first plate are coincident. ### Claim 25 (depends on 24) A capacitive sensor according to claim 24, wherein said overpressure stop member defines an aperture region disposed about said central axis, and wherein said post passing through said aperture region, said post having a first end connected to the central region of said elastic member and a second end connected to said second plate, said post being adapted for transferring the deformation of said central region to the movement of said second plate. ### Claim 26 (depends on 20) A capacitive sensor according to claim 20, wherein said first plate is mounted to said outer surface of said overpressure stop member. ### Claim 27 (depends on 26) A capacitive sensor according to claim 26, wherein said first plate and said overpressure stop member define an aperture region disposed about said central axis, and wherein said post passing through said aperture region, said post having a first end connected to the central region of said elastic member and a second end connected to said second plate, said post being adapted for transferring the deformation of said central region to the movement of said second plate. ### Claim 28 (depends on 20) A capacitive sensor according to claim 20, wherein said elastic member is an elastic diaphragm. ### Claim 29 (depends on 20) A capacitive sensor according to claim 20, wherein said elastic member is an elastic plate. ### Claim 30 (depends on 20) A capacitive sensor according to claim 20, wherein said elastic member is an elastic beam. ### Claim 31 (depends on 20) A capacitive sensor according to claim 20, wherein said elastic member is made from a material selected from a group of steel, stainless steel, ceramic and glass. ### Claim 32 (depends on 20) A capacitive sensor according to claim 20, wherein said overpressure stop member is made of a substantially rigid material. ### Claim 33 (depends on 20) A capacitive sensor according to claim 20, wherein said elastic member is substantially flat. ### Claim 34 (depends on 20) A capacitive sensor according to claim 20, wherein said elastic member is dome-shaped. ### Claim 35 (depends on 20) A capacitive sensor according to claim 20, wherein said inner surface of said overpressure stop member is substantially planar. ### Claim 36 (depends on 20) A capacitive sensor according to claim 20, wherein said inner surface of said overpressure stop member is concave. ### Claim 37 (depends on 36) A capacitive sensor according to claim 36, wherein said inner surface of said overpressure stop member is contoured such that said inner surface of said overpressure stop member fully and uniformly supports said central region when said central region deflected to a predetermined extent. ### Claim 38 (depends on 20) A capacitive sensor according to claim 20 further comprising a boss extending from said central region along said central axis. ### Claim 39 (depends on 20) A sensor according to claim 20, wherein said inner surface of said overpressure stop member has a contour adapted to limit deflection of said central region of said elastic member caused by a differential pressure across said elastic member. ### Claim 40 (depends on 20) A capacitive sensor according to claim 20, wherein said inner surface of said overpressure stop member defines a support contour which substantially conforms to a configuration defined by said elastic member when said elastic member deflected to a predetermined extent. ### Claim 41 (depends on 20) A sensor according to claim 20, wherein said pressure differential derives from a pressure being in contact with said first side of said elastic member and a constant, controlled environment being in contact with said second side of said elastic member.