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Digital system for controlling mechanical instrument gauges

  • US 4,939,675 A
  • Filed: 12/22/1988
  • Issued: 07/03/1990
  • Est. Priority Date: 12/22/1988
  • Status: Expired due to Term
First Claim
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1. A firmware/hardware electronic analog meter control system used with a multi-measurand data communication system for measuring a chosen measurand and then moving a needle of a gauge of the meter in a manner analogous to changes in magnitude of the measurand to positions indicated by a series of integer numbers arranged linearly over a display scale of the gauge, the scale representing a range of magnitudes of the measurand from a minimum to a maximum value, the meter containing digital to analog conversion circuits and coil drivers for controlling needle movement, said system having a transducer arranged to sense the magnitude of the measurand, said system comprising:

  • (a) first computing means connected to the transducer for (1) receiving the magnitude of the measurand, (2) establishing a number in an internal storage memory corresponding to the magnitude of the measurand occurring during each period of a succession of measuring periods, (3) converting each number into an equivalent measurement unit, (4) converting each said measurement unit into a digital coded message format, and (5) thereafter producing at an output the digital coded message at an end of each counting period;

    (b) communications means including an input transmitter/receiver device, a communications link and an output transmitter/receiver device said communications means having said input transmitter/receiver device connected to an output of said first computing means for sequentially sending each of said digital coded messages in a chosen format over said link at the end of each period; and

    (c) second computing means connected to said output transmitter/receiver device for (1) receiving each digital coded message, (2) converting each of said digital coded message into (i) a target deflection count and (ii) an update count from each of said digital coded messages, and thereafter computing a current deflection count using said target deflection and update counts, (3) incrementing said current deflection count by said update count at a chosen rate within each counting period of the measurand to establish a series of new current deflection counts such that each new current deflection count has an integer and a fractional part, and (4) upon the occurrence of a change of the integer part, producing at an output terminal another digital coded message that routes over said communications means to the meter, the meter containing a digital to analog converting circuit that responds to said another coded message to effect a deflection change of the needle.

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