Basic principle of load cell - Solutions - Huaqiang Electronic Network

inductance

The elastic body (elastic element, sensitive beam) is elastically deformed by an external force, so that the strain gauge (conversion element) attached to the surface thereof is simultaneously deformed. After the resistance strain gauge is deformed, its resistance value will change (increase or decrease), and then the corresponding measurement circuit converts this resistance change into an electrical signal, thereby completing the process of converting the external force into an electrical signal. It can be seen that the resistance strain gauge, the elastomer and the detection circuit are indispensable parts of the resistance strain type load cell. The following is a brief discussion of these three aspects. 1. Resistance strain gauge The resistance strain gauge mechanically distributes a resistance wire on a substrate made of an organic material. An important parameter of the strain gauge is the sensitivity coefficient K. When both ends are subjected to F force, they will elongate, that is, they will be deformed. When stretched, the cross-sectional area is reduced and the radius of the cross-section circle is reduced. The resistance change rate (resistance change) of the strain gauge is proportional to the elongation of the resistance wire (relative change in length). It should be noted that the sensitivity coefficient K is a constant determined by the properties of the metal resistance wire material, and is independent of the shape and size of the strain gauge. The K value of different materials is generally between 1.7 and 3.6. Secondly, the K value is a dimensionless quantity with no dimension. In material mechanics, ΔL/L is called strain, and it is called ε. It is often used to indicate that the elasticity is too large and inconvenient. It is often referred to as με as one unit of its unit. 2. The elastomeric elastomer is a structural member with a special shape. It has two functions, firstly bearing the external force of the load cell, generating a reaction force to the external force and achieving a relative static balance. Secondly, providing a high-quality strain field (zone) to compare the resistance strain gauges pasted in this area. Ideally, the conversion task of the electrical signal is completed. 3. The function of the detection circuit detection circuit is to convert the resistance value change of the resistance strain gauge into a voltage output. Because the Wheatstone bridge has many advantages, such as suppressing the influence of temperature changes, lateral force interference can be suppressed, and the compensation problem of the load cell can be solved conveniently, so the Wheatstone bridge is obtained in the load cell. A wide range of applications. The load cell uses a full-bridge equal-arm bridge, mainly because the full-bridge arm bridge has the highest sensitivity, the parameters of each arm are the same, and the effects of various disturbances easily cancel each other out.