FORCE-MEASURING APPARATUS INCLUDING TOTALIZER MEANS
First Claim
1. Weighing apparatus, comprising a. a stationary member including means defining a stationary magnetic field;
- b. a movable member normally having an initial no-load position relative to said stationary member;
c. electromagnetic compensation means operable upon the application to said movable member of a weight to be measured for returning said movable member to said no-load position, said compensation means including 1. compensation coil means mounted on said movable member, and 2. means for supplying to said compensation coil direct-current pulses of constant height and of a length that corresponds with the instantaneous extent of displacement of said movable member from said no-load position, thereby to establish in said compensation coil means a restoring magnetic field relative to said stationary magnetic field, said pulse supplying means including a. position detecting means for generating a displacement signal the magnitude of which corresponds with the extent of displacement of the movable member from the no-load position;
b. means including an oscillator and a first frequency divider for generating a sawtooth voltage of a relatively high frequency;
c. means including normally-open switch means operable to connect a source of direct current with said compensation coil; and
d. pulse length modulator means for periodically closing said switch means for periods of time that correspond with the magnitude of said displacement voltage relative to the instantaneous magnitude of said sawtooth voltage;
d. pulse counter means;
e. gate means operable by said pulse length modulator means for supplying counting pulses from said oscillator to said counter means during the periods of time said switch means is closed by said pulse length modulator, whereby said counter means continuously totalizes said pulses;
f. counter pulse storage and display means; and
g. means for periodically transferring to said storage and display means the instantaneous totalized value of the pulses in said counter means, said transfer means including 1. second frequency divider means connected with said first frequency divider means for producing transfer pulses of a relatively low frequency, and 2. counter control means operable by said low frequency transfer pulses for transferring the totalized condition of said counter means to said storage and display means and for resetting said counter to zero.
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Accused Products
Abstract
Force-measuring apparatus of the type including electromagnetic compensation means having a movable member that is returned to a no-load position relative to a stationary member by the supply of compensating current pulses of constant amplitude and variable length to a compensation coil secured to said movable member, characterized by the provision of counter means for counting subtotal numbers of counting pulses during periods corresponding with the lengths of said compensating current pulses, respectively, and means including counter control means for periodically transferring to store means the total value of the successive subtotals in the counter means and for simultaneously resetting the counter means to zero. Coarse control means are provided for causing the totalized subtotal pulse count to correspond with a decimal multiple or fraction of a weight unit, and additional store means are provided for optionally indicating for each of a series of subtotal measuring operations the net arithmetic difference between the totalized value and a given pulse reference value (such as tare). According to an alternate embodiment, means including subtotal rate selection switch means are provided for establishing low and high frequency subtotal rates, respectively, and stage selection switch means are operable in conjunction with the operation of said rate switch selection switch means for supplying the counting pulses to corresponding low and high stages, respectively, of the counter.
27 Citations
9 Claims
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1. Weighing apparatus, comprising a. a stationary member including means defining a stationary magnetic field;
- b. a movable member normally having an initial no-load position relative to said stationary member;
c. electromagnetic compensation means operable upon the application to said movable member of a weight to be measured for returning said movable member to said no-load position, said compensation means including 1. compensation coil means mounted on said movable member, and 2. means for supplying to said compensation coil direct-current pulses of constant height and of a length that corresponds with the instantaneous extent of displacement of said movable member from said no-load position, thereby to establish in said compensation coil means a restoring magnetic field relative to said stationary magnetic field, said pulse supplying means including a. position detecting means for generating a displacement signal the magnitude of which corresponds with the extent of displacement of the movable member from the no-load position;
b. means including an oscillator and a first frequency divider for generating a sawtooth voltage of a relatively high frequency;
c. means including normally-open switch means operable to connect a source of direct current with said compensation coil; and
d. pulse length modulator means for periodically closing said switch means for periods of time that correspond with the magnitude of said displacement voltage relative to the instantaneous magnitude of said sawtooth voltage;
d. pulse counter means;
e. gate means operable by said pulse length modulator means for supplying counting pulses from said oscillator to said counter means during the periods of time said switch means is closed by said pulse length modulator, whereby said counter means continuously totalizes said pulses;
f. counter pulse storage and display means; and
g. means for periodically transferring to said storage and display means the instantaneous totalized value of the pulses in said counter means, said transfer means including 1. second frequency divider means connected with said first frequency divider means for producing transfer pulses of a relatively low frequency, and 2. counter control means operable by said low frequency transfer pulses for transferring the totalized condition of said counter means to said storage and display means and for resetting said counter to zero.
- b. a movable member normally having an initial no-load position relative to said stationary member;
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2. Apparatus as defined in claim 1, and further including coarse and fine calibration means for so adjusting the weight value of an individual counting pulse relative to the number of totalized individual results as to effect representation of the measured result as a decimal multiple of a weight unit.
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3. Apparatus as defined in claim 2, wherein said fine calibration means comprises means for adjusting the amplitude of the compensating current pulses produced by said constant current source.
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4. Apparatus as defined in claim 2, wherein said coarse calibration means includes means associated with said counter control means for suppressing each of a given multiple of said counting pulses.
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5. Apparatus as defined in claim 1, and further including indicating means connected with said store means for providing a visible indication of all but the last decimal place of the total pulse count contained in said store means.
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6. Apparatus as defined in claim 1, wherein said pulse counter is reversible;
- and further including h. tare storage means;
i. tare switch means for initially storing in said tare storage means a number of pulses that corresponds with the tare weight;
j. means operable upon initial activation of said counter means for transferring the tare pulses from said tare store means to said counter;
k. forward-reverse logic means for causing said counter to initially operate in the reverse direction to subtract the weight pulses from the tare pulses; and
l. zero detector means operable when the number of tare pulses in the counter has been reduced to zero for causing the forward-reverse logic means to reverse the counting direction of said counter, whereby said counter again counts in the forward direction.
- and further including h. tare storage means;
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7. Apparatus as defined in claim 1, wherein said totalizing means includes rate selection switch means for alternately selecting first and second rates at which the subtotal counting operations are performed.
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8. Apparatus as defined in claim 7, wherein one of said rates of counting operations is a decimal multiple of the other.
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9. Apparatus as defined in claim 8, wherein said counter means includes a plurality of decimal stages, and further including stage selection switch means for supplying said counting pulses to that stage of said counter means that corresponds with the rate of subtotal counting operations selected by said rate selection switch means, respectively.
Specification