Pressure sensor is the most commonly used sensor in industrial practice. Generally, the output of an ordinary pressure sensor is an analog signal, and an analog signal refers to a continuous signal in which the information parameter appears within a given range. Or in a continuous time interval, the characteristic quantity of its representative information can be presented as a signal of any value at any instant. The pressure sensors we usually use are mainly manufactured by the piezoelectric effect, and such sensors are also called piezoelectric sensors.
Pressure sensor is the most widely used sensor. Traditional pressure sensors are mainly mechanical structural devices, and use the deformation of elastic elements to indicate pressure. However, this structure is large in size and heavy in mass, and cannot provide electrical output. With the development of semiconductor technology, semiconductor pressure sensors have also emerged. Its characteristics are small size, light weight, high accuracy and good temperature characteristics. Especially with the development of MEMS technology, semiconductor sensors are developing towards miniaturization, with low power consumption and high reliability.
When we choose a pressure sensor, we have to consider its comprehensive accuracy. What are the influences on the accuracy of the pressure sensor? Or what causes the error of the sensor? In fact, there are many factors that cause sensor errors. Below we pay attention to four unavoidable errors, which are the initial errors of the sensor.
The first offset error: Since the vertical offset of the pressure sensor remains constant throughout the pressure range, the change in the spread of the converter and the laser adjustment correction will produce an offset error.
Secondly, the sensitivity error: the size of the error is proportional to the pressure. If the sensitivity of the device is higher than the typical value, the sensitivity error will be an increasing function of pressure. If the sensitivity is lower than the typical value, the sensitivity error will be a decreasing function of pressure. The cause of this error is the change in the diffusion process.
The third is linearity error: this is a factor that has a small effect on the initial error of the pressure sensor. The cause of the error is the physical nonlinearity of the silicon chip, but for the sensor with an amplifier, the nonlinearity of the amplifier should also be included. The linear error curve can be a concave curve or a convex curve load cell.
Finally, the hysteresis error: In most cases, the hysteresis error of the pressure sensor is completely negligible, because the silicon chip has a high mechanical rigidity. Generally, only the hysteresis error needs to be considered when the pressure changes greatly.
These four errors of the pressure sensor are unavoidable. We can only choose high-precision production equipment, use high technology to reduce these errors, and perform a little error calibration when leaving the factory to reduce the error as much as possible. Meet customer needs.