Accurate weight measurement using digital to analog converter means and analog to digital converter means
AssigneeLoad Cells Inc.
InventorWarren Sarkison
Life of this patent
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Abstract
Electronic scale apparatus includes a face transducer having a first analog output; digital to analog converter circuitry having a second output; a first differential amplifier to receive such outputs and to produce a third output; and a second differential amplifier to receive the third output and output of the converter circuitry to produce another output. A major portion of the weight of the object being weighed is determined at the output of the first differential amplifier (i.e. a coarse measurement). The remaining portion or difference is then amplified and balanced out at the second differential amplifier, enabling accurate determination of weight and driving of the digital to analog converter in feed-back mode.
Claims9
In an electronic scale apparatus, the combination comprising
- (a) a force transducer having a first analog output that is ultimately converted to a digital output,
- (b) the digital output being fed to a digital to analog converter means having a second output,
- (c) a first differential amplifier operatively connected with said tranducer and converter to receive, as inputs, signals corresponding to said first and second outputs, and to produce a third output corresponding to the amplified difference between said first and second outputs,
- (d) and a second differential amplifier operatively connected with the output of said first differential amplifier and with said output of the converter means to receive, as inputs, signals corresponding to said third output and to a fourth output of the converter, and to a produce a fifth output corresponding to the difference between said third and fourth outputs, said fifth output driven in a direction to balance the third and fourth outputs.
Dependencies are inferred from the claim text.