# US 4,394,405 A · Method of making force transducer flexure > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 4,394,405 A - Document ID: US4394405A - Status: Granted - Kind: A - Application number: 06/283,130 - Filed: 1981-07-14 - Granted: 1983-07-19 - Earliest claimed: 1981-07-14 - Assignees: Sundstrand Data Control, Inc. - Inventors: Kim W. Atherton - Web page: https://patentgrep.com/patent/US4394405A ## CPC - G01P 15/132: {with electromagnetic counterbalancing means} - G01P 2015/0828: {the mass being of the paddle type being suspended at one of its longitudinal ends} - G01P: MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT (measuring or recording blood flow A61B5/02, A61B8/06; monitoring speed or deceleration of electrically-propelled vehicles B60L3/00; vehicle lighting systems adapted to indicate speed B60Q1/54; determining position or course in navigation, measuring ground distance in geodesy or surveying G01C; combined measuring devices for measuring two or more variables of movement G01C23/00; measuring velocity of sound G01H; measuring velocity of light G01J7/00; measuring direction or velocity of solid objects by reception or emission of radiowaves or other waves and based on propagation effects, e.g. Doppler effect, propagation time, direction of propagation, G01S; measuring speed of nuclear radiation G01T; measuring acceleration of gravity G01V; {measuring or recording the speed of trains B61L23/00; speed indicators incorporated in motor vehicles B60K35/00; measuring frequency or phase G01R; traffic control G08G}) ## Abstract The necessity for rigorously controlling process variables or making physical measurements is eliminated in a method of manufacturing a flexure for use in connecting a force sensing element to a mounting base in a force transducer where indicator portions are provided in a blank and material is removed uniformly from the blank including indicator portions until the indicator portions disappear. This process can also be used to configure a flexure out of a unitary piece of material such as fused quartz where a blank is masked except for indicator portions on each surface of the blank and at least one other surface portion; material is removed from the non-masked portions of the blank; and after removing the mask, material is removed from the blank until the indicator portions disappear. ## Claims ### Claim 1 A method of manufacturing a flexure for use in connecting a force sensing element to a mounting base in a force transducer comprising: providing a blank with two opposed surfaces; removing material from a first portion and a first indicator portion of one of said surfaces; removing material from a second indicator portion in the other of said surfaces wherein at least a portion of said indicator portion is directly opposite from said first indicator portion; and discontinuing removal of material from said first portion when at least a portion of the material of said blank between said first and second indicator portions disappears such that at least a portion of said indicator portion surfaces meet. ### Claim 2 (depends on 1) The method of claim 1 wherein the material from said first portion, and said first indicator portion and said second indicator portion is removed in a substantially identical manner. ### Claim 3 (depends on 1) The method of claim 1 wherein said other surface includes a second portion and including removal of material from said second portion in a substantially identical manner as said first portion. ### Claim 4 (depends on 3) The method of claim 3 wherein said second portion is not directly opposite said first portion. ### Claim 5 (depends on 1, 2) The method of claim 1 or 2 wherein the surface of said first portion is substantially coincident with the neutral bending plane of the flexure when the removal of material is discontinued. ### Claim 6 (depends on 3, 4) The method of claim 3 or 4 wherein the surfaces of said first and said second portions are substantially coincident with the neutral bending plane of the flexure when the removal of material is discontinued. ### Claim 7 (depends on 1, 2, 3, 4) The method of claim 1, 2, 3 or 4 wherein said material is removed by etching. ### Claim 8 A method of manufacturing a flexure for use in connecting a force sensing element to a mounting base in a force transducer comprising: providing a blank with two opposed surfaces; masking said blank except for opposed indicator portions on each of said surfaces and at least one surface portion; removing a predetermined amount of material from the non-masked portions of said blank; removing said mask from said blank; continuing removal of the material from a flexure section of said blank; and terminating removal of material from said flexure section of said blank when at least a portion of the material between said first and second indicator portions disappears such that at least a portion of said indicator portions meet. ### Claim 9 (depends on 8) The method of claim 8 wherein said masking step additionally includes masking a second surface portion in the blank surface opposing the surface that includes the first surface portion and wherein said first and second surface portions are not directly opposite one another. ### Claim 10 (depends on 9) The method of claim 9 wherein said material is removed such that the surfaces of said first and second surface portions are in the same plane when said removal of said material is terminated. ### Claim 11 (depends on 9) The method of claim 9 wherein said surfaces of said first and second surface portions are substantially coincident with the neutral bending plane of the flexure when said removal of said material is terminated. ### Claim 12 In the manufacture of a force transducer having a movable element hinged to a base by a bendable flexure, the movable element having an electrical circuit component thereon, the improved method of forming the flexure section, comprising: providing a transducer blank having a flexure section with parallel faces generally at right angles to the sensitive axis of the movable element; and removing material from a portion of at least one face of said flexure section to form a conductor receiving channel, the bottom surface of such channel lying substantially in the neutral bending plane of said flexure section. ### Claim 13 (depends on 12) The flexure forming method of claim 12 in which material is removed from portions of each face of the flexure section at the same time and at the same rate to form a pair of oppositely facing conductor receiving channels, each having a bottom surface lying substantially in the neutral bending plane of said flexure section. ### Claim 14 (depends on 12) The flexure forming method of claim 12 including: removing material from an opposed pair of indicator areas on each face of said blank, simultaneously with and at the same rate material is removed from the face of said flexure section; and terminating removal of material from the face of said flexure section when the opposed indicator areas break through. ### Claim 15 (depends on 14) The flexure forming method of claim 14 including the step of detecting when the opposed indicator areas break through and thereafter terminating removal of material from said flexure section. ### Claim 16 (depends on 12) The flexure forming method of claim 12 wherein said channels are laterally spaced apart. ### Claim 17 (depends on 12) The flexure forming method of claim 12 wherein said channels extend the length of the flexure section from the base to the movable element. ### Claim 18 (depends on 12) The flexure forming method of claim 12 including the step of applying a conductor on the bottom surface of each of said channels and extending from said base to said movable element. ### Claim 19 In the manufacture of a force transducer having a movable element hinged to a base by a bendable flexure, the movable element having an electrical circuit component thereon, the improved method of forming the flexure section, comprising: providing a transducer blank having a flexure section with parallel faces extending from said base to said movable element, said parallel faces being generally at right angles to the sensitive axis of the movable element; removing material from a portion of at least one face of said flexure section to form a conductor receiving channel; removing material from a pair of opposed indicator areas on each face of said blank, simultaneously with and at the same rate material is removed from said channel of said flexure section; and terminating removal of material from the face of said flexure section when the opposed indicator areas break through, the bottom surface of said channel lying substantially in the neutral bending plane of said flexure section. ### Claim 20 In the manufacture of a force transducer having a movable element hinged to a base by a bendable flexure, the movable element having an electrical circuit component thereon, the improved method of forming the flexure section, comprising: providing a transducer blank of a fused quartz material, having a flexure section with parallel faces generally at right angles to the sensitive axis of the movable element; removing material from a portion of each face of said flexure section to form a pair of oppositely facing conductor receiving channels; removing material from a pair of opposed indicator areas on each face of said blank, simultaneously with and at the same rate material is removed from said channels of said flexure section; and terminating removal of material from said channels of said flexure section when the opposed indicator areas break through, the bottom surface of each channel lying substantially in the neutral bending plane of said flexure section. ### Claim 21 (depends on 20) The flexure forming method of claim 20 in which the material is removed from said blank by etching. ### Claim 22 (depends on 21) The flexure forming method of claim 21 in which the material is removed from said blank by acid etching. ### Claim 23 (depends on 21) The flexure forming method of claim 21 in which the material is removed from said blank by plasma etching. ### Claim 24 (depends on 21) The flexure forming method of claim 21 in which the material is removed from said blank by ion beam milling. ### Claim 25 A method of manufacturing a flexure for use in connecting a force sensing element to a mounting base in a force transducer comprising: providing a transducer blank with two opposed surfaces; removing material from a first indicator portion of one of said surfaces to provide an indicator surface with a predetermined recess depth; removing additional material from said indicator portion and at least one other portion of at least one of said surfaces to form a flexure region on said blank; and discontinuing removal of material from the flexure region when at least a portion of said indicator surface breaks through and disappears. ### Claim 26 (depends on 25) The method of claim 25 wherein material is removed from a second indicator portion in the other of said opposed surfaces. ### Claim 27 (depends on 26) The method of claim 26 wherein said first and second indicator portions are at least partially directly opposed such that they may mutually meet and break through at a portion of their indicator surfaces at some point in processing. ### Claim 28 (depends on 27) The method of claim 27 wherein material is removed from at least one channel portion in one of said opposed surfaces such that the surface of said channel portion remains substantially coplanar with the indicator portion located in the same one of said opposed surfaces. ### Claim 29 (depends on 28) The method of claim 28 wherein the surface of at least one channel portion is substantially coincident with the neutral bending plane of the flexure when the removal of material is discontinued. ### Claim 30 (depends on 26, 27, 28) The method of claim 26, 27 or 28 wherein processing of corresponding portions on opposed surfaces of the blank is substantially identical, resulting in substantial symmetry of the corresponding surface planes with respect to the midplane of the blank. ### Claim 31 (depends on 28, 29) The method of claim 28 or 29 wherein substantially identical processing is achieved through concurrent processing. ### Claim 32 (depends on 30) The method of claim 30 wherein substantially identical processing of the opposed surfaces of the blank is achieved through concurrent processing of the opposed surfaces.