美国MIRC公司的一份研究报告指出,1990年美国用于过程控制的传感器年收入将近20亿美元,而到1997年将超过30亿美元,平均每年增长6.7％。其中主要是温度,压力、流量、液位和接近传感器,增长最快的是接近传感器,它在1990年增长率为10.5％。然而由于90年代美国仍处在经济衰退之中, According to a study by MIRC Corporation in the United States, the annual sensor revenue for process control in the United States was nearly 2 billion U.S. dollars in 1990, and it will exceed 3 billion U.S. dollars in 1997, an average annual increase of 6.7%. Among them are temperature, pressure, flow, level, and proximity sensors. The fastest-growing proximity sensor is its growth rate of 10.5% in 1990. However, because the United States was still in a recession in the 1990s,