創新式三維光學近接感測器及讀取電路設計

Abstract

本論文提出所謂「創新式三維光學近接感測器」，是一種非接觸型的感測器，不需觸碰即可感測物體靠近程度。此裝置是發光二極體與有機光偵測器的元件特性應用結合，藉由發光二極體產生一光訊號，經由被測物體反射而被有機光偵測器接收，以偵測的光電流強度來判斷物體的移動情形。特別之處在於使用有機元件來製作近接感測器，能夠降低製作成本、可撓曲及可做成大面積在軟性基板上。利用這些特性可以在未來應用到非觸碰式螢幕或虛擬鍵盤的發展上。「光學近接感測器」的問題在於，有機光偵測器接收可見光的波長範圍很廣，會在發光二極體打開前有環境光電流產生，造成當發光二極體打開時無法鎖定有機發光二極體波長的光源，使偵測的光電流會包括環境光電流及物體反射回來的所接收的電流。本設計電路創新之處在於操作方式是透過主動式像素電路、取樣和保持電路、放大器電路，電路上以低功率與低成本作為設計原則，再透過模擬決定設計晶片之參數，並以FPGA燒錄所需之時序控制完成整體電路之操作，目的是消除環境光電流影響，以正確判別出物體反射回來有機光偵測器所接收的光電流所對應的輸出電壓，並藉由LABVIEW建構出的人機介面，實現即時追蹤物體移動情形在三維座標平面上。研究晶片經由財團法人國家實驗研究院晶片系統設計中心贊助，使用台灣積體電路公司 0.35μm 2P4M 3.3V混合訊號互補式金屬氧化半導體製程完成，晶片之面積為 0.55 × 0.85 mm2。

The thesis proposes a novel 3D optical proximity sensor. It is a non-contact positioning sensor, which can sense the approaching distance of objects without touching. This device is composed of light-emitting diodes and home-made polymer photo-detectors. The light-emitting diode produces a light signal, and then the light signal is received by the polymer photo-detector via reflections of the measured object. Organic polymer materials attract a lot of interests since they can reduce the cost of manufacture, can become flexible, and can make the large area on flexible substrate. As a result of these characteristics, the optical proximity sensor could be applied on the development of the non-touching panel or flexible keyboard in the future. The problem of the optical proximity sensor is that the wide spectrum response range of the polymer photo-detector causes the polymer photo-detector to receive the background current before the light-emitting diode is turned on, which results in the polymer photo-detector being unable to locate the peak emission of the light-emitting diode when the light-emitting diode is turned on. Therefore, the polymer photo-detector detected the photocurrent, which included the background current and the current which is received by reflections of the measured object. The design of the circuit is the operation principle through active pixel circuit, sampling circuit, amplifier circuit and the decision of proposed chip parameters is determined by circuit simulation. The circuit is regarded low power and low cost as the design principle. Furthermore, the time sequence control is generated by FPGA to accomplish the operation of the whole circuit. The aim is to remove background current, and to detect the corresponding output voltage of photocurrent that is received by the polymer photo-detector via reflections of the measured object. Finally, the human machine interface is constructed by LABVIEW to create 3D vision tracing of sensed object. The proposed chip, with a die area of 0.55×0.85 mm2 is patronized by National Applied Research Laboratories National Chip Implementation Center (NARL NCIC), accomplished by using Taiwan Semiconductor Manufacturing Company (TSMC) 0.35μm 2P4M 3.3V mixed‐signal CMOS process.