Electrical filters for weighing system circuits

{
  "publication_number": "US3643753A",
  "country": "US",
  "kind": "A",
  "title": "Electrical filters for weighing system circuits",
  "abstract": "A weighing system comprising a transducer operatively connected to a load supporting structure for producing a DC analogue signal voltage having an amplitude which represents a weight condition of a load applied to the structure, at least one signal utilization device, and a circuit for transmitting the DC signal voltage to the signal utilization device and including an electrical filter for attenuating undulating voltage superimposed to the DC signal voltage. The filter includes an amplifier and is characterized by a variable impedance connected to the input of the amplifier for selectively varying the time response of the filter without altering the DC gain thereof. The damping coefficient of the filter is a function only of a preselected value of the percentage by which the filter output voltage initially overshoots its steady state value when the transducer voltage is applied as a step input to the filter.",
  "claims": [
    "1. In a weighing system having means for supporting a load, means operatively connected to said load-supporting means for providing an analogue signal voltage having an amplitude that is a function of a weight condition of a load applied to said supporting means, signal utilization means, and means interconnecting said analogue signal voltage-providing means and said utilization means for applying said signal voltage to said signal utilization means and comprising an electrical multiple pole filter circuit for attenuating undulating voltages superimposed on said signal voltage, the improvement comprising means forming a part of said circuit for varying the time response of said circuit to the application of said signal voltage to said circuit without altering the DC gain thereof.",
    "2. The weighing system defined in claim 1 wherein said circuit comprises an amplifier having an output electrically connected to said signal utilization means, and wherein said time-response varying means comprises impedance means having a selectively adjustable resistance for varying said time response, said impedance means being connected between said analogue signal voltage-providing means and an input terminal of said amplifier to provide a path for applying the signal voltage produced by said signal voltage-providing means to the input circuit of said amplifier.",
    "3. The weighing system defined in claim 2 wherein said electRical circuit further includes first resistance means connected serially between said analogue signal-providing means and said impedance means to form with said impedance means an electrical, signal-transmitting network, second resistance means providing a feedback connection from the output of said amplifier to said network between said first resistance means and said impedance means and coacting with said first resistance means to determine said gain.",
    "4. the weighing system defined in claim 3 wherein said electrical circuit further comprises first capacitance means providing a further feedback connection from the output of said amplifier to said network between said impedance means and said input of said amplifier and second capacitance means connected between a source of reference potential and the junction between said network and said second resistance means.",
    "5. The weighing system defined in claim 3 wherein said impedance means comprises a potentiometer.",
    "6. In a weighing system having load-supporting means, means operatively connected to said supporting means for providing an analogue signal voltage having an amplitude that is a function of a weight condition of a load applied to said supporting means, signal utilization means, and means interconnecting said analogue signal voltage-providing means and said utilization means and comprising an underdamped electrical multiple pole filter for attenuating undulatory voltages superimposed upon said signal voltage and being responsive to a sudden application of said signal voltage for producing an output voltage having a substantially steady-state value following an initial predetermined overshoot of said steady-state value, said interconnecting means applying said output voltage to said utilization means, and said filter having a damping coefficient which is a function only of a preselected percentage of said overshoot relative to said steady-state value.",
    "7. The weighing system defined in claim 6 wherein said damping coefficient is substantially proportional to the algebraic expression wherein M is equal to the natural logarithim of the percentage of overshoot divided by 100 and wherein said percentage of overshoot is equal to the first peak value of said output voltage divided by said steady-state value.",
    "8. In a weighing system having load-supporting means, means operatively connected to said supporting means for producing an analogue signal voltage having an amplitude that is a function of a weight condition of a load applied to said supporting means, signal utilization means, means interconnecting said analogue signal voltage-providing means and said utilization means, an underdamped electrical multiple pole filter forming a part of said interconnecting means for attenuating undulatory voltages superimposed upon said analogue signal voltage and comprising an amplifier having its output connected to said utilization means for applying the output voltage of said filter to said utilization means, an impedance circuit branch having one terminal to which said signal voltage is applied for filtering and a second terminal connected to the input of said amplifier, and means providing a feedback connection from the output of said amplifier to said one terminal, said impedance circuit branch being substantially proportional to the algebraic expression wherein H is equal to the DC gain of said filter, and wherein M is a function only of a preselected percentage by which the output voltage of said filter initially overshoots its steady-state value in response to a sudden application of said analogue signal voltage to said one terminal.",
    "9. In a weighing system having load-supporting means, means operatively connected to said supporting means for providing an analogue signal having an amplitude that is a function of a weight condition of a load applied to said supporting means, signal utilization means, and means interconnecting said analogUe signal-providing means and said utilization means and comprising an underdamped multiple pole filter for attenuating undulatory voltages superimposed upon said signal and being responsive to a sudden application of said signal for producing an output signal having a substantially steady state value following an initial predetermined overshoot of said steady state value, said output signal being applied to said utilization means by said interconnecting means, and said filter having a damping coefficient which is a function only of a preselected percentage of said overshoot relative to said steady state value.",
    "10. In a weighing system having means for supporting a load, means operatively connected to said load-supporting means for providing an analogue signal voltage having an amplitude that is a function of a weight condition of a load applied to said supporting means, signal utilization means, and means interconnecting said analogue signal voltage-providing means and said utilization means and comprising an underdamped electrical multiple pole filter circuit for attenuating undulating voltages superimposed on said signal voltage and being responsive to a sudden application of said signal voltage for producing an output voltage having a substantially steady state value following an initial predetermined overshoot of said steady-state value, said output voltage being applied to said utilization means by said interconnecting means, the improvement comprising means forming a part of said circuit for varying the overshoot of said output voltage in response to the sudden application of said signal voltage to said circuit without altering the gain thereof.",
    "11. A weighing system for measuring a weight condition of a load within a preselected tolerance range of the true value of said condition, wherein said range is defined by preselected maximum and minimum weight condition values which are respectively greater than and lesser than said true value, said weighing system comprising a load-supporting means, means operatively connected to said supporting means for providing an analogue signal voltage having an amplitude which represents said weight condition of the load applied to said supporting means, signal utilization means, means interconnecting said analogue signal voltage-providing means and said utilization means for applying said signal voltage to said utilization means and comprising an electrical multiple pole filter for attenuating undulatory voltages superimposed upon said signal voltage, and means forming a part of said filter to provide said filter with a predetermined underdamped response to a step form of said signal voltage which initially overshoots a steady state voltage value corresponding to the amplitude of said signal voltage and which, upon entering the band of voltage values representing said range of weight condition values, remains within said band and has an initial overshoot peak value that at least closely approaches a voltage value representing said maximum weight condition value.",
    "12. A weighing system for measuring a weight condition of a load within a preselected tolerance range of the true value of said condition, wherein said range is defined by preselected maximum and minimum weight condition values which are respectively greater than and lesser than said true value, said weighing system comprising a load-supporting means, means operatively connected to said supporting means for providing an analogue signal having an amplitude which represents said weight condition of the load applied to said supporting means, signal utilization means, means interconnecting said analogue signal-providing means and said utilization means for applying said analogue signal to said utilization means and comprising a filter for attenuating undulatory waveforms superimposed upon said analogue signal, and means forming a part of said filter to provide said filter with an underdamped response to a step form of said analogue voltage which initially overshoots a steady stAte value corresponding to the amplitude of said analogue signal and which, upon entering the band of values representing said range of weight condition values, remains within said band and has an initial overshoot peak value that at least closely approaches said maximum weight value.",
    "13. In a weighing system having means for supporting a load, means operatively connected to said load-supporting means for producing an analogue signal voltage having an amplitude that is a function of a weight condition of a load applied to said supporting means, signal utilization means, means interconnecting said analogue signal voltage-providing means and said utilization means and comprising an underdamped electrical multiple pole filter circuit for attenuating undulating voltages superimposed on said signal voltage and being responsive to a sudden application of said signal voltage for producing an output voltage having a substantially steady-state value following an initial predetermined overshoot of said steady-state value, said output voltage being applied to said utilization means by said interconnecting means, said filter having a damping coefficient that is a function only of a preselected percentage of said overshoot relative to said steady-state value, and said filter further having a time response that is dependent upon the value of said damping coefficient, and impedance means forming a part of said filter and having a selectively variable resistance for selectively adjusting said damping coefficient without altering the DC gain of said filter.",
    "14. The weighing system defined in claim 13 wherein said weight condition represents any deviation of the weight of the load applied to said supporting structure from a preselected value.",
    "15. The weighing system defined in claim 1 wherein said weight condition represents any deviation of the weight of the load applied to said supporting means from a preselected value."
  ],
  "cpc": [
    "G01G 23/10",
    "G01G 15/00",
    "H03H 11/126"
  ],
  "assignees": [
    "HOWE RICHARDSON SCALE CO"
  ],
  "filing_date": "1969-09-03",
  "publication_date": "1972-02-22",
  "grant_date": "1972-02-22",
  "priority_date": "1969-09-03",
  "application_number": "US-3643753D-A",
  "family_id": "25320075",
  "citations": [
    "US2849669A",
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    "US3042128A",
    "US3113631A",
    "US3172493A",
    "US3209846A",
    "US3288231A"
  ]
}