Balance with free-floating weighing pan
AssigneeMettler-Toledo AG
InventorDaniel Reber
Life of this patent
Estimating the term…
Abstract
A balance (1) has a weighing pan (3) that is held in a predetermined free-floating and constant position relative to translatory and rotary displacements in the six degrees of freedom during use. At least six position sensors are used to measure the position of the weighing pan in all three dimensions. A weighing mechanism having at least six electromagnetic mechanisms (5) generate compensation forces (Fc1-Fc6) that act on the weighing pan by sending currents through a force coil (7) associated with an associated permanent magnet. The weight of an object on the weighing pan is determined from the amounts of current flowing in the respective force coils to maintain the weighing pan in position.
Claims18
A balance, comprising:
- a weighing pan;
- at least six position sensors, arranged to measure the position of the weighing pan in all three dimensions;
- a weighing mechanism with at least six electromagnetic mechanisms, each of which includes at least one permanent magnet and at least one force coil, such that the weighing mechanism generates compensation forces to act, through currents sent to each force coil, in each of the six translatory and rotatory degrees of freedom on the weighing pan, based upon the orientation and position of each force coil relative to the weighing pan;
- a regulating unit to regulate the individual currents flowing in the force coils, wherein the compensation forces, through the sum of their respective moments, hold the weighing pan in a constant, predefined and free-floating position relative to the six degrees of freedom;
- and
- an arithmetic unit provided with software to calculate the weighing result based on the amounts of current flowing in the respective force coils.
A method for operating a balance, wherein the method comprises the steps of:
- measuring the position of a weighing pan of the balance in all three dimensions by means of the at least six position sensors;
- generating, during the weighing process, a compensation force in each of at least six electromagnetic mechanisms associated with the weighing pan to act on the weighing pan in the six translatory and rotatory degrees of freedom of the weighing pan, each of the electromagnetic mechanisms including at least one permanent magnet and at least one force coil, wherein the compensation force is generated by a current sent through each force coil, depending on the respective position and orientation of the force coil relative to the weighing pan;
- simultaneously regulating the respective current flowing in each force coil, so that the compensation forces, through the sum of their respective moments, hold the weighing pan in a predetermined, free-floating and constant position relative to the six degrees of freedom;
- and
- calculating a weighing result from the amounts of current flowing in the respective force coils.
Dependencies are inferred from the claim text.