Load-compensating weighing apparatus including signal modifying means
First Claim
1. In a weighing apparatus of the return-to-zero load compensating type including a support (20);
- a weighing pan (10) normally having a given zero position relative to said support;
means operable when the pan is displaced from the zero position by the application of a load thereto for returning the pan to its zero position, comprising pan sensing means (30) for generating a position signal (Ua) which is a function of the degree of displacement of the pan from its zero position, control signal generating means (32,
52) responsive to said position signal for generating a pan return signal (UR), and pan return means (14,
16) operable by said pan return signal for returning the pan to its zero position; and
indicating means (36,
38) responsive to said pan return signal for providing an indication that is a function of the magnitude of the load applied to the pan;
the improvement which comprisesthreshold circuit means including voltage-responsive impedance means having a severely curved voltage characteristic connected between said pan sensing means and said pan return means for modifying those pan position signals (Ua) having an amplitude less than a given amplitude, thereby to reduce the effect of external interference vibrations and accelerations on the control means and to increase the stability of the indication presented by said indicating means.
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Accused Products
Abstract
Weighing apparatus of the return-to-zero load compensation type is disclosed, characterized by the provision of voltage-responsive impedance means for modifying the pan position sensing signal to remove undesirable variations therein produced by interference or external vibrations or excessive swinging of the weighing pan by the load. In one embodiment, a dampening circuit is connected between the pan position sensing circuit and the control signal generating means for dampening sensing signals having an amplitude less than a given limit amplitude. In a second embodiment, the voltage-responsive means serves to render inoperable the differential section of a proportional-differential-integral controller when the pan position sensing signals are less than a given limit amplitude. In both embodiments, the voltage-responsive impedance means comprises a pair of diodes connected in polarity opposition in parallel in the corresponding signal-modifying circuit.
46 Citations
6 Claims
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1. In a weighing apparatus of the return-to-zero load compensating type including a support (20);
- a weighing pan (10) normally having a given zero position relative to said support;
means operable when the pan is displaced from the zero position by the application of a load thereto for returning the pan to its zero position, comprising pan sensing means (30) for generating a position signal (Ua) which is a function of the degree of displacement of the pan from its zero position, control signal generating means (32,
52) responsive to said position signal for generating a pan return signal (UR), and pan return means (14,
16) operable by said pan return signal for returning the pan to its zero position; and
indicating means (36,
38) responsive to said pan return signal for providing an indication that is a function of the magnitude of the load applied to the pan;
the improvement which comprisesthreshold circuit means including voltage-responsive impedance means having a severely curved voltage characteristic connected between said pan sensing means and said pan return means for modifying those pan position signals (Ua) having an amplitude less than a given amplitude, thereby to reduce the effect of external interference vibrations and accelerations on the control means and to increase the stability of the indication presented by said indicating means. - View Dependent Claims (2, 3, 4, 5, 6)
- a weighing pan (10) normally having a given zero position relative to said support;
Specification