壓電傳感器的工作原理詳解
1、壓電效應
壓(ya)(ya)電(dian)(dian)(dian)(dian)效應是(shi)(shi)壓(ya)(ya)電(dian)(dian)(dian)(dian)傳感器工作的(de)(de)(de)基礎。當壓(ya)(ya)電(dian)(dian)(dian)(dian)材(cai)料受到外(wai)力(li)作用時，其(qi)內部會產生電(dian)(dian)(dian)(dian)極化(hua)現(xian)象，在材(cai)料表面出現(xian)正(zheng)負相反(fan)的(de)(de)(de)電(dian)(dian)(dian)(dian)荷。常(chang)見的(de)(de)(de)壓(ya)(ya)電(dian)(dian)(dian)(dian)材(cai)料有石英(ying)晶(jing)體(ti)、鈦酸(suan)鋇(bei)等(deng)。以石英(ying)晶(jing)體(ti)為(wei)(wei)例，其(qi)結晶(jing)形(xing)狀為(wei)(wei)六角形(xing)晶(jing)柱，當沿特(te)定方(fang)向施加外(wai)力(li)時，晶(jing)胞(bao)中(zhong)(zhong)正(zheng)負離子相對位移，導(dao)致(zhi)正(zheng)負電(dian)(dian)(dian)(dian)荷中(zhong)(zhong)心(xin)不(bu)(bu)(bu)再重合，從而產生宏觀極化(hua)，在晶(jing)體(ti)表面出現(xian)電(dian)(dian)(dian)(dian)荷。壓(ya)(ya)電(dian)(dian)(dian)(dian)常(chang)數是(shi)(shi)衡量壓(ya)(ya)電(dian)(dian)(dian)(dian)材(cai)料性能的(de)(de)(de)重要參數，不(bu)(bu)(bu)同的(de)(de)(de)壓(ya)(ya)電(dian)(dian)(dian)(dian)材(cai)料壓(ya)(ya)電(dian)(dian)(dian)(dian)常(chang)數不(bu)(bu)(bu)同。
2、電荷放大
電(dian)(dian)(dian)(dian)荷放大是(shi)將壓(ya)(ya)(ya)電(dian)(dian)(dian)(dian)材(cai)料產(chan)生(sheng)的(de)微小電(dian)(dian)(dian)(dian)荷進(jin)行放大的(de)過程。電(dian)(dian)(dian)(dian)荷放大器(qi)(qi)通常由一(yi)個(ge)高(gao)(gao)輸入阻(zu)抗的(de)運(yun)算放大器(qi)(qi)構(gou)成。運(yun)算放大器(qi)(qi)能夠將壓(ya)(ya)(ya)電(dian)(dian)(dian)(dian)材(cai)料產(chan)生(sheng)的(de)電(dian)(dian)(dian)(dian)荷轉換為電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)信號(hao)，并將其放大。例如(ru)(ru)，單(dan)電(dian)(dian)(dian)(dian)源系統輸出電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)將高(gao)(gao)于和(he)(he)(he)低(di)于連接到同相輸入端子(zi)的(de)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)。如(ru)(ru)果運(yun)算放大器(qi)(qi)有負電(dian)(dian)(dian)(dian)源軌，則可以將同相輸入端子(zi)接地；如(ru)(ru)果使用單(dan)電(dian)(dian)(dian)(dian)源系統，則通常需要提供偏置電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)，一(yi)般為電(dian)(dian)(dian)(dian)源電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)的(de)一(yi)半，但(dan)具體(ti)偏置電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)的(de)選(xuan)擇可根據輸出信號(hao)的(de)正(zheng)偏差(cha)和(he)(he)(he)負偏差(cha)情(qing)況進(jin)行調整(zheng)。為了(le)提高(gao)(gao)電(dian)(dian)(dian)(dian)荷放大器(qi)(qi)的(de)性(xing)(xing)能，需要注(zhu)意以下幾點：一(yi)是(shi)選(xuan)擇合(he)適的(de)壓(ya)(ya)(ya)電(dian)(dian)(dian)(dian)材(cai)料和(he)(he)(he)結構(gou)，以獲得(de)更(geng)好(hao)的(de)靈(ling)敏度(du)和(he)(he)(he)線(xian)性(xing)(xing)度(du)；二是(shi)設(she)計合(he)理的(de)信號(hao)處理電(dian)(dian)(dian)(dian)路，提高(gao)(gao)輸出信號(hao)的(de)穩定性(xing)(xing)和(he)(he)(he)抗干(gan)擾(rao)能力(li)；三(san)是(shi)優(you)化(hua)安裝和(he)(he)(he)使用條件(jian)，減小誤差(cha)和(he)(he)(he)保證測量精度(du)；四是(shi)注(zhu)意保護壓(ya)(ya)(ya)電(dian)(dian)(dian)(dian)材(cai)料和(he)(he)(he)電(dian)(dian)(dian)(dian)路，避免過載和(he)(he)(he)損壞(huai)。
3、輸出信號
經過電荷放大后的信號為電壓信號或電流信號，輸出到后續電路進行處理。壓電傳感器的輸(shu)(shu)出(chu)信(xin)號(hao)可(ke)以通過電(dian)纜或無線(xian)方(fang)式傳輸(shu)(shu)。在傳輸(shu)(shu)過程中，需要考慮信(xin)號(hao)的穩定(ding)性和(he)(he)抗干擾能力。為了提(ti)高(gao)輸(shu)(shu)出(chu)信(xin)號(hao)的質量，可(ke)以采(cai)取以下措(cuo)施：一是選擇合適的傳輸(shu)(shu)方(fang)式和(he)(he)電(dian)纜，減(jian)少(shao)信(xin)號(hao)衰減(jian)和(he)(he)干擾；二是對(dui)輸(shu)(shu)出(chu)信(xin)號(hao)進行濾(lv)波和(he)(he)放大，提(ti)高(gao)信(xin)號(hao)的信(xin)噪比(bi)；三是采(cai)用(yong)數字(zi)信(xin)號(hao)處理(li)技術，對(dui)輸(shu)(shu)出(chu)信(xin)號(hao)進行數字(zi)化處理(li)，提(ti)高(gao)信(xin)號(hao)的精(jing)度和(he)(he)可(ke)靠性。
