屏蔽層厚度對投射電容式觸控面板的影響

Abstract

本論文研製以有限元素分析軟體 COMSOL 模擬投射電容式觸控面板，在 TFT-LCD 顯示面板與觸控面板間置入 ITO 屏蔽層，找出屏蔽層的厚度對投射電容式觸控面板的靈敏度及感應線訊雜比的影響。首先取得現有 15.6吋市售筆記型電腦搭載的投射電容式觸控面板，使用 LCR Meter 量測該觸控面板的驅動線和感應線之間的電容值，在手指有觸碰和沒有觸碰的狀態下，電容值會改變，可以計算出該觸控面板的靈敏度，進而使用電荷放大器將有雜訊時感應線電荷量的轉換成電壓值，使用示波器量測電壓的變化，計算出該觸控面板的訊雜比。第二部分使用有限元素分析軟體 COMSOL 建立簡易該 15.6 吋投射電容式觸控面板的模型，模擬屏蔽層厚度的增加，投射電容式觸控面板靈敏度的變化;當有雜訊源時，屏蔽層厚度的增加對投射電容式觸控面板訊雜比的影響，從屏蔽層厚度對投射電容式觸控面板靈敏度及訊雜比的交互影響下可以得到屏蔽層的厚度最佳化。

A procedure is using finite element analysis software “COMSOL” to build a projected capacitive touch panel model. Then insert ITO shielding layer between projected capacitive touch panel and TFT-LCD. To study the thickness of shielding layer impact to sensitivity of projected capacitive touch panel and SNR of sense line. First, get 15.6” projected capacitive touch panel form notebook computer. Use LCR Meter to measure capacitance of touch panel when touched the touch panel by human finger or not. We can calculate the sensitivity of this projected capacitive touch panel. Then transfer the electric charge to voltage by charge amplifier. Measure the voltage change by Oscillator, then calculate SNR of touch panel. Second, build simple 15.6” projected capacitive touch panel model with COMSOL. Change the thickness of ITO shielding layer to find out the change of sensitivity of projected apacitive touch panel. Add noise source to this model, study the change of etymology of electricity of sense line. Base on the simulation result that the change of sensitivity of projected capacitive touch panel and the change of SNR when ITO shielding layer’s thickness changed, we will get the optima ITO shielding layer thickness.