Automatic electronic distance indicator

• US 3,219,925 A
• Filed: 05/10/1960
• Issued: 11/23/1965
• Est. Priority Date: 06/25/1959
• Status: Expired due to Term

• Current Assignee: Henry Guilford Leslie, Roderick Borley Colin
• Original Assignee: Henry Guilford Leslie, Roderick Borley Colin
• Inventors: RODERICK BORLEY COLIN, HENRY GUILFORD LESLIE
• Application Number:
  US04/028,088
• Time in Patent Office: 2,023 Days
• US Class Current: 324/662
• CPC Class Codes: G01B 7/00 Measuring arrangements characterised by the use of electric or magnetic techniques
• CPC Class Codes: G01B 7/02 for measuring length, width or thickness G01B7/004, G01B7/12 take precedence
• CPC Class Codes: G01D 5/20 by varying inductance, e.g. by a movable armature
• CPC Class Codes: G01D 5/2046 by a movable ferromagnetic element, e.g. a core

Claims

1. MEASURING APPARATUS COMPRISING A MEMBER HAVING A SERIES OF UNIFORMLY SPACED DISCONTINUITIES DISPOSED ALONG A PREDETERMINED LENGTH OF A GIVEN AXIS THEREOF, SAID DISCONTINUITIES FORMING AN INTEGRAL HELICAL CONDUCTIVE SURFACE OF SAID MEMBER HAVING A PITCH SUBSTANTIALLY EQUAL TO AND COINCIDENTAL WITH THE SPACING BETWEEN SAID DISCONTINUITIES AND BEING PROPORTIONAL TO A PREDETERMINED SCALAR QUANTITY, FIRST AND SECOND ELECTRICAL SENSOR MEANS IN FIXED RELATIONSHIP TO ONE ANOTHER AND IN PREDETERMINED CAPACITIVE SENSING COUPLING RELATIONSHIPS, RESPECTIVELY, WITH SAID DISCONTINUITIES, EACH OF SAID FIRST AND SECOND SENSOR MEANS COMPRISING A HELICAL CONDUCTIVE SURFACE HAVING THE SAME PITCH AS SAID MEMBER, AND BEING DISPOSED CONCENTRICALLY ABOUT SAID MEMBER AND SAID GIVEN AXIS TO SENSE SAID DISCONTINUITIES IN A GROUP OF AT LEAST ONE DISCONTINUITY EACH TO PROVIDE RESPECTIVE FIRST AND SECOND OUTPUT SIGNALS, EACH OF SAID FIRST AND SECOND OUTPUT SIGNALS BEING PROPORTIONAL TO THE RELATIVE POSITION OF THE RESPECTIVE SENSOR MEANS WITH RESPECT TO THE GROUP BEING SENSED THEREBY, MEANS FOR CAUSING RELATIVE MOVEMENT OF SAID FIRST AND SECOND SENSOR MEANS WITH RESPECT TO SAID GROUP TO VARY SAID RELATIVE POSITION AND CAPACITANCE THEREBETWEEN, EACH OF SAID FIRST AND SECOND SENSOR MEANS HAVING EXCLUSIVE FIRST AND SECOND RELATIVE POSITIONS FOR EACH DISCONTINUITY OF THE GROUP BEING SENSED THEREBY TO PROVIDE A PREDETERMINED BALANCED CONDITION FOR SAID FIRST AND SECOND SIGNALS WHEN BOTH SAID SENSOR MEANS ARE AT SAID RESPECTIVE FIRST RELATIVE POSITIONS AND WHEN BOTH SAID SENSOR MEANS ARE AT SAID SECOND RELATIVE POSITIONS, COMPARISON MEANS RESPONSIVE TO SAID FIRST AND SECOND OUTPUT SIGNALS TO PROVIDE AN INDICATING SIGNAL HAVING FIRST AND SECOND VALUES IN THE PRESENCE AND ABSENCE, RESPECTIVELY, OF SAID BALANCED CONDITION, SAID COMPARISON MEANS COMPRISING A BRIDGE CIRCUIT HAVING THE RESPECTIVE CAPACITANCES BETWEEN EACH OF THE SENSOR MEANS AND RESPECTIVE GROUPS BEING SENSED THEREBY COUPLED IN THE RESPECTIVE ARMS THEREOF AND OUTPUT MEANS FOR SAID INDICATING SIGNAL, AND DISCRIMINATING MEANS COMPRISING THIRD ELECTRIC SENSOR MEANS IN CAPACITIVE SENSING COUPLING RELATIONSHIP WITH SAID MEMBER DISCONTINUITIES AND RESPONSIVE TO THE RELATIVE POSITIONING OF SAID FIRST AND SECOND SENSOR MEANS WITH RESPECT TO SAID MEMBER TO DISCRIMINATE BETWEEN THE FIRST VALUES OF SAID INDICATING SIGNAL RELATED TO A PREDETERMINED ONE OF THE TWO SAID FIRST AND SECOND POSITIONS AND THE FIRST VALUE RELATED TO THE OTHER OF THE TWO SAID FIRST AND SECOND RELATIVE POSITIONS.