Scale with overload detection measured by auxiliary voltage
AssigneeWipotec GmbH
InventorsAlexander Schulzki, Jan Gottfriedsen
Life of this patent
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Abstract
A device and method for detection of an overload on a scale which operates by the principle of electromagnetic force compensation The device and method employing, in addition to the measurement voltage arising across a measurement resistor of the scale, an auxiliary voltage that is different from the measurement voltage. The auxiliary voltage being tapped at the input to the compensation coil of the scale or at the output of the compensation coil.
Claims18
A scale which operates by the principle of electromagnetic force compensation, the scale including:
- (a) a magnet;
- (b) a compensation coil movable relative to the magnet;
- (c) an output stage having an output connected to the compensation coil to supply an electrical current to the compensation coil to maintain the position of the compensation coil relative to the magnet;
- (d) a measurement resistor connected in series with the compensation coil between the compensation coil and a reference voltage;
- (e) an auxiliary measurement voltage node located between the output of the output stage and the compensation coil or between the compensation coil and the measurement resistor to provide an auxiliary measurement voltage;
- and
- wherein a measurement resistor voltage across the measurement resistor is representative of a weight measurement value for the scale when a load force within a first load force range is introduced onto a load receiving element of the scale, and the auxiliary measurement voltage indicates an overload case when a load force outside the first load force range is introduced onto the load receiving element of the scale.
A method for a scale which operates by the principle of electromagnetic force compensation and including a magnet, a compensation coil movable relative to the magnet, and an output stage having an output connected to the compensation coil to supply an electrical current to the compensation coil to maintain the position of the compensation coil relative to the magnet, the method including:
- (a) measuring a measurement resistor voltage across a measurement resistor connected between the compensation coil and a reference voltage, the measurement resistor voltage being representative of a weight measurement value for the scale when a load force within a first load force range is introduced onto a load receiving element of the scale;
- and
- (b) at least when the measurement resistor voltage or a signal generated therefrom exceeds a presettable voltage limit value therefor, measuring and evaluating an auxiliary measurement voltage tapped between the output of the output stage and the compensation coil or between the compensation coil and the measurement resistor, the auxiliary measurement voltage or a signal generated therefrom indicating an overload case when a load force outside the first load force range is introduced onto the load receiving element of the scale.
A method for testing an overload safety device in a scale which operates by the principle of electromagnetic force compensation and including (i) a magnet, (ii) a compensation coil movable relative to the magnet, (iii) an output stage having an output connected to the compensation coil to supply an electrical current to the compensation coil to maintain the position of the compensation coil relative to the magnet when a load force within a first load force range is introduced onto a load receiving element of the scale, (iv) a measurement resistor connected in series with the compensation coil between the compensation coil and a reference voltage, and (v) a measurement resistor voltage output providing an output of a voltage across the measurement resistor, the method including:
- (a) evaluating an auxiliary measurement voltage tapped between the output of the output stage and the compensation coil or between the compensation coil and the measurement resistor to determine a value corresponding to an actuating force of the overload safety device;
- and
- (b) comparing the auxiliary measurement voltage or a signal generated therefrom to one or more presettable limit values in order to identify an occurrence of an actuation of the overload safety device.
Dependencies are inferred from the claim text.