US 5,656,800 A · Accurate and responsive weighing apparatus with drift compensation

Abstract

In order to increase both the weighing accuracy and the weighing speed of a weighing apparatus, a delta.multidot.sigma analog-to-digital converter (4) having a cut-off frequency higher than that of an analog filter (3) is connected with the output of the analog filter (3). Also, in order to perform a quick drift correction of an amplifier (2), the analog filter (3) is selectively switchable so as to perform a filtering function during a weighing mode and to perform a buffering function during a correction mode correcting means (52) is provided for storing the digital signal from the delta.multidot.sigma analog-to-digital converter (4) as a drift signal (df) during the correction mode and for providing a corrected digital weight signal (d2) by subtracting the drift signal (dr) from the digital weight signal (d1) obtained from the delta.multidot.sigma-type analog-to-digital converter (4) during the weighing mode.

Claims16

Dependent claims

A weighing apparatus for weighing a load and for providing a digital weight signal used to display the weight of the load comprising:

at least one weighing means, said weighing means further comprising:
a weight detector for detecting the weight of the load and outputting an analog weight signal;
an amplifier for amplifying the analog weight signal;
and
an analog filter with a first cut off frequency for reducing a high frequency component of the amplified analog weight signal which is higher than said first cut-off frequency;
and
at least one delta-sigma analog-to-digital converter, said converter further comprising:
a modulator for modulating the amplified analog weight signal output from the analog filter into a digital signal, and
a digital filter with a second cut-off frequency for reducing a high frequency component of the digital signal which is higher than said second cut-off frequency, wherein the second cut-off frequency is higher than the first cut-off frequency, thereby to provide the digital weight signal.

6 more elements

A weighing apparatus for weighing a load and for providing a digital weight signal used to display the weight of the load comprising:

at least one weighing means, said weighing means further comprising:
a weight detector for detecting the weight of the load and outputting an analog weight signal;
an amplifier for amplifying the analog weight signal;
and
an analog filter with a first cut off frequency for reducing a high frequency component of the amplified analog weight signal which is higher than said first cut-off frequency, wherein the first cut off frequency is of a value corresponding to a mechanical vibration of the weight detector;
and
at least one delta-sigma analog-to-digital converter said converter further comprising:
a modulator for modulating the amplified analog weight signal output from the analog filter into a digital signal, and
a digital filter with a second cut off frequency for reducing a high frequency component of the digital signal which is higher than said second cut-off frequency, wherein the second cut-off frequency is higher than the first cut-off frequency, thereby to provide the digital weight signal.

6 more elements

Dependencies are inferred from the claim text.

Accurate and responsive weighing apparatus with drift compensation

Life of this patent

Accurate and responsive weighing apparatus with drift compensation

Life of this patent

Abstract

Claims16