高效的電容式感應(yīng)設(shè)計優(yōu)化

　　現(xiàn)代點和點擊編程軟件取代了舊的焊料和希望設(shè)計電容傳感接口的方法。

　　近年來，在廣泛的應(yīng)用中，人們使用電容式傳感接口，從移動電話到計算機、服務(wù)終端到家用電子設(shè)備，以及醫(yī)療設(shè)備到工業(yè)控制，都有很大幅度的增長。本文將探討電容傳感設(shè)計方法的演變，并概述超越猜測和焊接方法的現(xiàn)代調(diào)諧過程，使開發(fā)人員能夠?qū)崟r校準(zhǔn)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(tǒng)機械按鈕和滑塊的方法。而感知一個按鈕的物理狀態(tài)，電容傳感檢測近觸屏導(dǎo)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(shè)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.