Mettler Instrumente Ag

Mettler Instruments Ag

Felix Strobel

Peter Kunz

Rudolf Stocker

Willi Kunz

Werner Zumbrunn

A circuit is described here for liquid crystal indication systems made up of segments which, using the capacitive performance of the indication system, automatically reveals errors that arise in the segments or due to short-circuits between segments. The invention is adapted for use especially in scales that are to be guaranteed against functional errors.

Multisegment liquid crystal indication system

In a scale wherein the signal signifying the weight is generated by counting of clock pulses over a weight-dependent part of a predetermined time interval, a second counter counts clock pulses in the remaining part of the predetermined time interval. These are added to the clock pulses counted during the weight-dependent part of the predetermined time interval and compared to a reference number which represents the total number of clock pulses in the predetermined time interval. An error signal is furnished if the two numbers do not correspond.

Error detecting apparatus for a scale having a digital display

An improved weighing apparatus of the electromagnetic load compensation type is disclosed, including a correction loop connected between the output terminal of the synchronizer and the input terminal of the pulse length modulator for varying the regulated load signal from the PID regulator to produce a corrected regulated load signal which compensates for digitalization errors produced by the synchronizer. In one embodiment, the correction loop includes an integrator circuit for superposing on the regulated load signal an inverted integrated error voltage the magnitude of which is a function of the operation of the synchronizer relative to the mark signals. In a second embodiment, the correction loop includes an integrator circuit that periodically applies to the regulated load signal a constant reference voltage of opposite polarity. Preferably, the reference voltage is applied simultaneously with the periods of supply of the compensation current.

Weighing apparatus including digitalization error correcting means

Weighing apparatus of the electromagnetic load compensation type is disclosed including protective shield means for protecting an asymmetrically arranged compensation coil against stray magnetic-flux and particles of contaminants, thereby to improve the accuracy of load measurement.

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Greifensee, Switzerland

Felix Strobel