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The Strain Gauge Load Cell Principle
Oct 12, 2017

The strain gauge load cell principle

The resistive strain type weighing sensor is based on the principle that: elastic body (elastic element, sensitive beam) produces elastic deformation under external force, so that the Resistance strain gage (conversion element) which is pasted on its surface is also deformed, and its resistance will change (increase or decrease) after deformation of the resistor strain plate, By the corresponding measuring circuit, the resistance change is converted to an electrical signal (voltage or current), thus the process of transforming the external force into an electrical signal is completed.

Thus, the resistance strain gage, elastomer and detection circuit are the essential parts of the resistance strain type weighing sensor.

1.Strain Gauge

The resistor strain Gage is a piece of strain that distributes a resistor wire mechanically on a substrate made of organic material. One of his important parameters is the sensitivity coefficient k.

The size of the K value of the sensitivity coefficient is a constant determined by the properties of the metal resistance wire material, which is independent of the shape and size of the strain gage, and the K value of the different materials is generally between 1.7-3.6; the second k value is a dimensionless quantity, that is, it has no dimensions.



The elastomer is a structural piece with a special shape. It has two functions, the first is that it withstands the external force of the weighing sensor, which produces a reaction to the external forces and achieves a relative static balance; Secondly, it will produce a high quality strain field (region), so that the resistance strain gage pasted in this area is more ideal to complete the transformation task of strain date signal.

3.Detection circuit

The function of the detecting circuit is to change the resistance of the Resistance strain gage to the voltage output. Because Wheatstone Deng Bridge has many advantages, such as can restrain the influence of temperature change, can restrain lateral force interference, can solve the compensation problem of weighing sensor conveniently, so the Wheatstone bridge is widely used in weighing sensor.

Because the full bridge type and other arm bridge sensitivity is the highest, each arm parameters are consistent, the impact of all kinds of interference easily offset each other, so weighing sensors are all bridge-type arm bridge.