US 4,375,243 A · Wide range high accuracy weighing and counting scale

Abstract

An electronic scale is provided with two or more load cells in which the first load cell covers a low load range, and each successive cell covers a greater load range than the preceding cell. The cells are connected mechanically in tandem such that a load on the scales is applied to each cell simultaneously. Electrical signals from each load cell when performing a weighing operation are processed by a microcomputer to digitize the signals and to select the signal coming from the first load cell in the tandem connection which is not overloaded. The microprocessor scales the measurement signal and displays the weight on an alphanumeric readout. Memory circuits are included for storing tare weights and for storing unit weights during counting operations. When a number of units in a group is to be counted, the microprocessor divides a measured weight by the unit weight and outputs the count to the alphanumeric readout display. A low profile of the tandem load cell arrangement is obtained by the use of Z-brackets or L-brackets to provide the mechanical interconnections. All switching of ranges is done automatically by the microprocessor without attention of the user.

Claims14

Dependent claims

A wide range weighing and counting scale comprising:

(a) a first load cell having a first range of operation, and a second load cell having a range of operation higher than said first load cell, said second load cell mechanically coupled in tandem with said first low range cell;
(b) first conditioning amplifier means connected to said first load cell to receive electrical signals therefrom for producing a digital count proportional to the load applied to said first load cell, said amplifier having a preselected upper count limit;
(c) second conditioning amplifier means connected to said second load cell to receive electrical signals therefrom for producing a digital count proportional to the load on said second load cell;
and
(d) computer means connected to said first and second conditioning amplifiers, said computer means for selecting the digital count for processing from said first conditioning amplifier when said count is less than a preselected upper limit, and for selecting the digital count from said second conditioning amplifier when said first count is greater than said selected upper limit, said computer means for calculating a number representative of the load on said scale from the selected digital count;
and
(e) display means for displaying said calculated number.

4 more elements

An electronic counting scale for determining the number of units in a group of units, said scale having a high count accuracy over a wide range of weights of said units comprising:

(a) memory means for temporarily storing the unit weight of objects to be counted;
(b) a base;
(c) a platform for holding the group of units to be counted;
(d) a multiplicity of load cells mechanically and operatively connected in tandem between said platform and said base, wherein each successive load cell after a first load cell has a greater weight capacity than the preceding load cell;
(e) a multiplicity of electronic amplifier means for providing excitation to each of said load cells, for receiving analog electrical signals therefrom representative of the weight of a group of units on said platform, and for amplifying each of said signals;
(f) means for selecting the amplified signal from the load cell in tandem connection having the highest value and for which the weight capacity of such load cell is not exceeded;
(g) means for converting said selected signal to a weight measurement signal;
(h) means connected to said memory means for dividing said weight measurement signal by said temporarily stored unit weight to thereby produce an electrical count signal representative of the number of units in said group;
and
(i) electronic display means for displaying the count of said group.

7 more elements

Dependencies are inferred from the claim text.

Wide range high accuracy weighing and counting scale

Life of this patent

Wide range high accuracy weighing and counting scale

Life of this patent

Abstract

Claims14