Electronic scales with two ranges
First Claim
1. An electronic balance comprising support means, at least one measuring member mounted on said support means, a measuring-bridge formed by strain gauges disposed on said at least one measuring member, two weighing or measuring scales associated with said strain gauges and means to change the scale adapted to operate in such a manner that the upper limits of the scales are in a predetermined ratio and that the output signal of the measuring-bridge is a linear function of the weight, wherein the ratio between the slope of said output signal of the measuring-bridge as a function of the weight of said lower scale and as a function of the weight of said upper scale is equal to the said predetermined ratio.
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Abstract
In order to obtain, in an electronic balance, ranges which are in a predetermined ratio, for example 1:10, there is provided a measuring arm provided with strain gauges adapted to measure the deformation of this arm when it is subjected to a constraint or force. Between the arm and a knife-edge there is disposed a measuring annulus likewise provided with strain gauges adapted to measure the deformation of this annulus when it is subjected to a weighing force. The balance is operated in such a manner that the force or mass of the weight to be measured at the moment of weighing is exerted firstly on the arm via the annulus, until the arm contacts the abutment. This determines the small measuring scale. If the weight is higher than this value, the force is subsequently exerted solely on the annulus which presents a resistance in the region of 10 times greater and determines the second measuring scale.
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Citations
7 Claims
- 1. An electronic balance comprising support means, at least one measuring member mounted on said support means, a measuring-bridge formed by strain gauges disposed on said at least one measuring member, two weighing or measuring scales associated with said strain gauges and means to change the scale adapted to operate in such a manner that the upper limits of the scales are in a predetermined ratio and that the output signal of the measuring-bridge is a linear function of the weight, wherein the ratio between the slope of said output signal of the measuring-bridge as a function of the weight of said lower scale and as a function of the weight of said upper scale is equal to the said predetermined ratio.
Specification