- 學位論文
有機薄膜元件組成之近紅外光距離感測裝置
Organic thin film devices based near-infrared proximity sensor
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摘要
近紅外光距離感測裝置是結合高分子發光二極體- Polymer Light Emitting Diode (PLED)與高分子光偵測元件-Polymer Photo Detector(PPD)。有機材料元件製程具有成本低廉、製程簡易、可製程於軟性基板且質量輕、以及可溶液製程大面積基板等優勢，符合智慧型機器人感測皮膚需求。若能在機器人表面披覆高密度的距離感測陣列(array)，其將不會在變化的環境中受到障礙物的影響。操作於近紅外光波長具有低色散、高反射率的低損耗、人眼視感度低，且可降低環境雜訊之干擾等優點。 近紅外光之產生是以高亮度綠光Green-B LED激發光轉換膜放光，再透過可見光濾光片濾除700nm之前的光所形成。光轉換膜材料為高放光效率螢光粉(phosphors)，測試其轉換效率(conversion rate)可達到20%以上；另以P3HT：PCBM為主動層材料之PPD，藉由控制其主動層的厚度與元件施加逆向偏壓，使PPD操作在-20V時，可偵測到波長650nm ~ 900nm的紅光與近紅外光。PPD偵測到光之電流大小，藉由後端電路將電流轉換成電壓訊號且放大，經由資料擷取卡(Data Acquisition card)，將PPD偵測物體之遠近訊號呈現至電腦。量測單一PPD pixel搭配四顆PLED提供偵測光源，在室內開日光燈的量測環境下，以白紙為物體在靠近偵測裝置10 cm時，PPD淨光電流(net photocurrent)變化達100nA以上，且電腦控制軟體可呈現出明顯的電壓訊號差異。依此為基礎，成功實現 array近紅外光距離感測裝置即時偵測物體位置的目標。
並列摘要
Near-infrared (NIR) proximity sensor combines a polymer light emitting diode (PLED) and a polymer photo detector ( PPD). It is easy for organic materials to be applied in large-area and flexible substrate due to their mechanic property, and they have potential for low-cost fabrication process . As a result, organic materials must be properly used to the skin of robots. If the skin of robots can be covered with a high density array of proximity sensors, it will be able to move in unstructured and unpredictable environments without collisions. For proximity sensors, there are many advantages to operate in the NIR range, such as low dispersion , low loss, low eye-sensing and low environment interference. The NIR emission is obtained by adding a color conversion film of phosphors to a green-emitting Green-B LED, and then through the visible light filter to be formed. Measuring the conversion efficiency from photoluminescence is over 20% . On the other hand, PPD with voltage-adjustable photoresponse from visible to NIR range (650nm~900nm). Poly(3-hexylthiophene) and (6,6)-phenyl-C61- butyric acid methyl ester (PCBM) blend is used as the active layer. The PPD detection photocurrent will be transfer to voltage signal by means of current to voltage operation amplifier, and then be presented in the computer by Data Acquisition card. To decrease the current for driving PLED, we use four PLED and one PPD. When the PLED is biased at 7 V and the PPD is biased at -20V, PPD can detect the net photocurrent over 100nA for white paper under ambient indoor lighting and detection distance 10 cm. Finally, we can obviously identify the difference between object-far and object-close voltage signals, and then we come to array NIR proximity sensor that can detect the location of the object immediately.
參考文獻
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