新穎主動式三維光學式近接感測陣列及其讀取電路設計與實現

Abstract

本論文提出了新式的「主動像素電路」(Active Pixel Sensor, APS)，以及結合主動像素電路與背景光減除電路的「三維光學式近接感測器讀取電路」，以達到感測近接物體的功能。三維光學式近接感測系統的目標是研發一套非接觸式的觸控面板，不但有一般市面上觸控面板所有的平面(二維)感測，還增加了第三軸高度的感測，而提升為「三維」的近接感測 ，不須觸碰到面板即可感測到物體位置。前端面板是由發光二極體 (LED)及光接收器所組成的陣列，由發光二極體發光照射到待偵測物體，並由光接收器接收反射光，由反射光的強度來判斷物體距離。為了適用於不同的環境及背景光下，需要經由特別設計的電路做背景光消除動作，最後再經由程式撰寫演算法與人機介面，計算出待測物體座標。而主動像素電路常用於互補式金氧半導體光感測器(CMOS SENSOR)中，是做為光接收器(Photo Detector, PD)的驅動電路，主要作用是將光感測器所偵測到的光強度轉換為電壓值，並且有增加解析度與降低外來雜訊的優點，而公認最標準且通用的架構是3T架構(3T-APS)，此電路有一缺點是此電路的輸出擺幅受到限制，最大值無法到達偏壓上限。本論文提出了新式的主動像素電路，能夠將輸出擺幅擴大到偏壓上限，因此增加了主動像素的解析度，不論是應用在互補式金氧半導體光感測器或是本論文的光學式近接感測電路上，都會比以往的3T架構有更好的輸出表現。電路成功下線至台積電0.35um2P4M 3.3V混合訊號互補式金氧半導體製程，將特別設計的電路由IC實現，並結合前端面板與後端程式構成整個系統，已實際測試其可行性。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，兩次下線的晶片面積分別為1.289×1.289 mm2 以及 0.8×1.220 mm2。

The study proposes a new active pixel sensor (APS) circuit and the associated 3D optical proximity sensing circuit to eliminate the effects of background lighting. The 3D optical proximity sensing system is a non-contact positioning sensor, which senses the approaching distances of objects without touching. The system is capable of 2D sensing and third-axis sensing, the 3D proximity sensing. This system is composed of light-emitting diodes and photo-detectors. The light emitting diode produces a light signal. The light signal is received by the photo detector via reflections of the measured object. The system determines the height of the object with the light intensity measured by the photo detector. In order to adapt to different environments, the study proposes a special circuit that eliminates the background light. After eliminating background light circuit, the results of the algorithm computation is illustrated by a LABVIEW program. A new active pixel sensor is also proposed in the study. The active pixel sensor is used to convert the light to the voltage, and it can improve the resolution and reduce the noise. The standard and official active pixel sensor is a 3T-structure APS (or 3T-APS). The drawback of 3T-APS is that the output range is limited by the original circuit design. The maximum output cannot be up to bias voltage. The new APS resolution is better than the standard 3T-APS resolution in this aspect. It is a good improvement in terms of not only the CMOS sensor but also the 3D optical proximity sensing circuit. The circuits are accomplished by Taiwan Semiconductor Manufacturing Company (TSMC) 0.35μm 2P4M 3.3V mixed‐signal CMOS process. The system is composed of the LED/PD array, designed IC and the LABVIEW program. The proposed chips, with the die area of 1.289×1.289 mm2 and 0.8× 1.220 mm2 are fabricated by National Applied Study Laboratories National Chip Implementation Center (NARL NCIC).