Vibrating string transducer devices and systems employing the same

• US 3,153,351 A
• Filed: 12/27/1957
• Issued: 10/20/1964
• Est. Priority Date: 12/27/1957
• Status: Expired due to Term

• Current Assignee: Paul J. Holmes
• Original Assignee: Paul J. Holmes
• Inventors: Holmes, Paul J.
• Application Number:
  US03/705,578
• Time in Patent Office: 2,489 Days
• US Class Current: 73/497
• CPC Class Codes: G01L 1/10 by measuring variations of frequency of stressed vibrating elements, e.g. of stressed strings using resistance strain gauges G01L1/22
• CPC Class Codes: G01P 15/10 by vibratory strings

Claims

1. IN A FORCE MEASURING SYSTEM, THE COMBINATION OF A FORCE RESPONSIVE ELEMENT, A PAIR OF PRESTRESSED ELASTIC STRAND, MEANS RESPECTIVELY CONNECTING SAID STRANDS TO SAID ELEMENT SUCH THAT MOVEMENT OF SAID ELEMENT DUE TO FORCE THEREON CAUSES AN INCREASE IN THE STRESS OF ONE OF SAID STRANDS AND A DECREASE IN THE STRESS OF THE OTHER OF SAID STRANDS, MEANS FOR VIBRATING EACH OF SAID STRANDS AT THE NATURAL FREQUENCY CORRESPONDING TO ITS STRESS, AND MEANS COMPRISING A FREQUENCY MIXER TO EFFECT SUMMATION OF THE FREQUENCY OF VIBRATION OF ONE OF SAID STRANDS AND A MULTIPLE OF THE FREQUENCY OF THE OTHER OF SAID STRANDS, A SOURCE OF PREDETERMINED REFERENCE FREQUENCY, FREQUENCY COMPARING MEANS HAVING CONNECTION WITH SAID SOURCE AND SAID MIXER FOR PROVIDING AN ERROR SIGNAL PROPORTIONAL TO ANY CHANGE IN THE SUM OF SAID FREQUENCIES, AND MEANS CONTROLLED BY SAID ERROR SIGNAL TO VARY ACCORDINGLY THE STRESSES OF SAID STRANDS TO CAUSE SAID SUM TO REMAIN CONSTANT WHEREBY THE DIFFERENCE IN THE FREQUENCIES OF VIBRATION OF SAID STRANDS IS CAUSED TO VARY LINEARLY WITH CHANGE IN FORCE ON SAID ELEMENT THROUGHOUT A GIVEN RANGE THEREOF.