![]() ![]() A device called a charge amplifier can be employed to convert the magnitude of the electrical charge in the crystal to an analog or digital output signal for display or processing. Measuring the amount of charge provides an indication of the magnitude of the weight or force applied to the piezoelectric crystal load cell. When subjected to a load or mechanical stress, the crystal becomes deformed which results in a change to the center of symmetry of the electrical charges for the crystal which produces a proportional change in the electrical charge, which then can be measured. In the absence of mechanical stress, the crystals are unstressed and exhibit a balanced electrical charge. Within the load cell are a set of crystal elements containing an electrode between the crystals. ![]() Piezoelectric crystal load cells are based on the concept of the piezoelectric effect, piezo a Greek word meaning “to squeeze”. Hydraulic load cells, as well as the similar pneumatic type, share the characteristic that they do not directly rely on the use of electrical current and therefore can be used in conditions where there is the risk of a potential explosive hazard. After proper calibration, the pressure reading can be converted into weight and read directly from an analog gauge or may be converted into an electrical output signal such a standard 4-20mA output. ![]() A pressure gauge monitors the change in pressure, whose value is directly proportional to applied weight or force. As a load is applied to the load cell, the weight of the object moves the piston which flexes the diaphragm and compresses the fluid in the chamber, causing an increase in the fluid pressure. A flexible diaphragm inside the load cell is mounted beneath a piston attached to a plate called the load platform. Hydraulic load cells are similar to pneumatic load cells and make use of a pressurized liquid such as hydraulic oil or water to balance out the applied load. The amount of pressure needed to balance out the weight of the object being measured can be used to measure the weight and can be converted to an electrical signal if needed. A pressure gauge measures the pneumatic pressure resulting from the weight applied. A flexible diaphragm is compressed when a compressive force is applied to the plate on the top surface of the load cell. ![]() Pneumatic load cells consist of a source of pressurized air or gas that is fed through a pressure regulator to a chamber inside the load cell. Load cells can use different technologies to produce an output and so different types of load cells are available, including: Load cells (sometimes spelled as loadcells) are a type of force sensor/force transducer that converts an applied force into an output signal that can be used to measure forces such as compressive forces, most commonly weight. The most common types of force sensors include Load Cells, Strain Gages, and Force Sensing Resistors (FSRs). Several different types of force sensors exist, each of which makes use of different technologies to sense the magnitude of a given force and create an output signal. To learn more about other sensors, review our related article Sensors - A Complete Guide (Types, Applications, and Suppliers). This article will provide information on force sensors, including the common types and how they work. They are used in a wide range of products and applications such as bathroom scales, musical instruments, medical applications, automobiles to detect seat occupancy, and process control in manufacturing facilities, to name a few of the many uses for these devices. Although strictly speaking force sensors and force transducers differ from each other, the two terms are most commonly used interchangeably.įorce sensors are available in a wide range of sizes and can be used to detect forces from fractions of an ounce to hundreds of tons. The signals may be sent to indicators, controllers, or computers to inform operators or serve as inputs to provide control over machinery and processes. Force sensors, are devices that are designed to translate applied mechanical forces, such as tensile and compressive forces, into output signals whose value can be used to reflect the magnitude of the force. ![]()
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