在選擇壓力傳感器的時(shí)候我們要考慮他的綜合精度,而壓力傳感器的精度受哪些方面的影響呢?其實(shí)造成傳感器誤差的因素有很多,下面我們注意說四個(gè)無法避免的誤差,這是傳感器的初始誤差。
首先的偏移量誤差:由于壓力傳感器在整個(gè)壓力范圍內(nèi)垂直偏移保持恒定,因此變換器擴(kuò)散和激光調(diào)節(jié)修正的變化將產(chǎn)生偏移量誤差。
其次是靈敏度誤差:產(chǎn)生誤差大小與壓力成正比。如果設(shè)備的靈敏度高于典型值,靈敏度誤差將是壓力的遞增函數(shù)。如果靈敏度低于典型值,那么靈敏度誤差將是壓力的遞減函數(shù)。該誤差的產(chǎn)生原因在于擴(kuò)散過程的變化。
第三是線性誤差:這是一個(gè)對(duì)壓力傳感器初始誤差影響較小的因素,該誤差的產(chǎn)生原因在于硅片的物理非線性,但對(duì)于帶放大器的傳感器,還應(yīng)包括放大器的非線性。線性誤差曲線可以是凹形曲線,也可以是凸形曲線稱重傳感器。
最后是滯后誤差:在大多數(shù)情形中,壓力傳感器的滯后誤差完全可以忽略不計(jì),因?yàn)楣杵哂泻芨叩臋C(jī)械剛度。一般只需在壓力變化很大的情形中考慮滯后誤差。
壓力傳感器的這個(gè)四個(gè)誤差是無法避免的,我們只能選擇高精度的生產(chǎn)設(shè)備,利用高新技術(shù)來降低這些誤差,還可以在出廠的時(shí)候進(jìn)行一定的誤差校準(zhǔn),盡最大的可能來降低誤差以滿足客戶的需要。
When choosing a pressure sensor, we should consider its comprehensive accuracy, and the accuracy of the pressure sensor by what aspects of the impact? Actually, there are many factors causing sensor error, we should pay attention to the following four unavoidable errors, this is the initial error of the sensor.
First offset error: Since the vertical offset of the pressure sensor remains constant throughout the pressure range, the variation of the converter diffusion and laser adjustment correction will produce offset error.
The second is 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, then the sensitivity error will be a decreasing function of pressure. The reason for this error lies in the change of diffusion process.
The third is the linear error: this is a small impact on the initial error of the pressure sensor, the error is due to the physical non-linearity of the silicon wafer, but for the sensor with amplifier, should also include the non-linearity of the amplifier. The linear error curve can be a concave curve or a convex curve weighing sensor.
Finally, the lag error: in most cases, the lag error of the pressure sensor can be neglected completely, because the silicon wafer has a high mechanical stiffness. In general, we only need to consider lagging error when the pressure changes greatly.
The four errors of pressure sensor are unavoidable, we can only choose high-precision production equipment, use high-tech to reduce these errors, but also in the factory to carry out a certain error calibration, as far as possible to reduce the error to meet customer needs.