The invention relates to an electric balance with a weight measured value sensor, having a temperature sensor for correcting temperature-dependent errors of the weight measured value sensor. The invention also has a built-in calibrating weight, with a device which can bring the calibrating weight into operative connection with the weight measured value sensor, with a display and control panel and with a microprocessor/digital signal processing unit which comprises a memory means for storing a calibrating factor.
Balances of this type are generally known and are described, for example, in DE-OS 31 44 103. A correction of temperature-dependent errors is not mentioned therein. However, this correction is likewise known, e.g. from DE-OS 32 13 016 or DE-OS 33 40 512.
The concept "calibrating weight" is intended to signify not only calibrating weights which act directly by virtue of their force of weight on the weight measured value sensor but also so-called "calibrating levers" in which the one-sided overweight of a rotatably mounted system exerts a defined force on the weight measured value sensor. Such calibrating levers are likewise described in the already-mentioned DE-OS 31 44 103.
A disadvantage of these known prior art constructions is the fact that the operator does not receive any instructions about when a new calibrating process is necessary. The operating instructions can only furnish general data but can not go into detail about the particular conditions for setting up the individual balance, so that in general one calibration per day was recommended.
The invention has the object of making available for the operator of the balance better and more appropriate information about any change of the balance sensitivity which may have occurred since the last calibration and to alert him as to when calibration should be reperformed or by use of the controlling microprocessor actually have the device automatically initiate and perform the calibration.
USPTO Backgrounds
USPTO Backgrounds