高效的電容式感應設計優化

　　現代點和點擊編程軟件取代了舊的焊料和希望設計電容傳感接口的方法。

　　近年來，在廣泛的應用中，人們使用電容式傳感接口，從移動電話到計算機、服務終端到家用電子設備，以及醫療設備到工業控制，都有很大幅度的增長。本文將探討電容傳感設計方法的演變，并概述超越猜測和焊接方法的現代調諧過程，使開發人員能夠實時校準傳感器，而不涉及編碼。

　　電容式傳感是一種基于觸覺的傳感方式，它提供了一種替代傳統機械按鈕和滑塊的方法。而感知一個按鈕的物理狀態，電容傳感檢測近觸屏導電物體的存在和接近傳感器的觸摸屏。通常，對象是人體的一部分，如手指。為了理解設計過程的演變，理解電容傳感的基本知識是很重要的。

　　Fundamental to any capacitive sensing solution are groups of conductors that interact with their surrounding electric fields. The human body itself is full of conductive electrolytes， covered by a poor dielectric： skin. The fact that our bodies， or more specifically our fingers， are conductive is what enables capacitive sensing for human interfaces.

　　If you examine a simple parallel-plate capacitor， you will find two conductors separated by a dielectric layer. The majority of the energy in this capacitor is focused between the two plates; however， some of the energy spills over to the area outside the plates. This spillage creates what is called fringing fields， referring to the overflow electric field lines. A well-designed capacitive sensor function requires controlling the PCB traces to prevent fringing fields spilling over into the active sensing area. As you might guess， a parallel-plate capacitor is not a good choice for our desired sensor pattern.