Mettler-toledo Gmbh

Mettler-toledo Ag

Mettler Instruments Ag

Mettler Instrumente Ag

Arthur Reichmuth

Bruno Nufer

Linus Meier

Fritz Fuchs

Martin Heusser

Christain Klebe

Willy Kunz

A balance () has a weighing pan () for receiving a load () to be weighed, and an electronic weighing module () which includes a measuring unit (). The balance is equipped with an electrostatic sensor () which is arranged so that accumulated electrostatic charges which reside on the load can be detected as the load is placed or about to be placed on the weighing pan. The balance is operated by using the electrostatic sensor to detect electrostatic charges, transferring information on a value characterizing the magnitude of the detected electrostatic charges to the measuring unit, comparing the value against a threshold value, and triggering an action of the electronic weighing module based on the comparison.

Balance with an electrostatic charge build-up sensor

An electronic balance weighs one and the same load of an arbitrary amount repeatedly in a serial test from which it determines a statistical quantity, preferably the standard deviation. Based on this determination, it is possible to state the uncertainty of subsequent measurements at the actual location. It is advantageous to use as the test load the weighing sample itself, so that its effect on the random errors will be included in the uncertainty. When the uncertainty at a given confidence level is defined as a requirement, then the result of the test may serve to determine the minimum allowable sample weight.

Electronic balance

Correction coefficients which permit effective linearization of an electronic scale over a measurement range may be determined by loading the scale individually and in combination with loads, at least one of the loads being unknown and uncalibrated.

Method for compensation of weighing errors in an electronic scale

In a process according to the invention for automatic calibration and/or linearization of a high-resolution electronic balance, point values are assigned by a function to the disturbance variables (parameters) that can affect the weighing result. A calibration and/or linearization is indicated or triggered when the accumulated point values reach a triggering point value (Xa) that is presettable, balance-specific and/or dependent on the environment. The calibration and/or linearization can also be triggered when the accumulated point value of a single disturbance variable reaches a triggering point value which is below point number (Xa).

Method for determining the necessity of adjusting a high-resolution

A weighing system including a weighing cell (1) which supplies a measurement signal (I) to an A/D converter (3) via a signal line (2). An interference signal (i), superposed on the measurement signal, is decoupled out of signal line (2) at the signal output of the weighing cell (1), rotated by means of an inverter (4) in terms of phase by 180.degree., and again coupled into the signal line (2) at the signal input of the A/D converter. An ohmic resistance (RO) is connected in series in the signal line (2) between the uncoupling node (AK) and the in-coupling node (EK). The interference signal (i) is decoupled preferably capacitively via a series circuit that forms the frequency-determining member of the active low-pass filter including a condenser (C) and an ohmic resistance (R1). On the other hand, a galvanic coupling (R3) is provided for the recoupling of the interference signal (-i). With this active low-pass filter, one can attain a substantially complete suppression of the interference signals without any subsequent adjustment of the filter.

Weighing apparatus including active low-pass filter means

Weighing apparatus of the electromagnetic load compensation type is provided with a movable coil arranged in the air gap of a permanent magnet system, and which includes a load-compensation winding through which flows a load-dependent compensation current. As a temperature sensor for measuring the coil temperature, use is made of the coil, specifically, either the load winding itself or an additional winding that is in thermal contact with it. A resistance measuring device determines its temperature-dependent resistance from the voltage and the current on or in the winding. Accurate and real-time measurement of the coil temperature as a measure for controlling the compensation of its influence on the measurement reading is possible in this way.

Electromagnetic load-compensation weighing apparatus including

The plurality of selector buttons or keys previously required for selecting a mode or parameter in an electrical scale is replaced by a single key. Depression of the key causes each of the available modes and/or parameters to be selected in sequence. The title of the then-present mode or parameter is displayed. When the desired mode or parameter has been reached the operator releases the key. Submodes or ranges within a given parameter are set by short depression of the key. The sequencing is controlled by a microcomputer. Jumpers may be provided so that certain modes or parameters are eliminated from the sequence for a given application.

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Wetzikon, Switzerland

Arthur Reichmuth