應用於互動式投影裝置之影子觸控技術

Abstract

觸控裝置已成為現今大多數電子裝置必備的主要元件之ㄧ，常見於一般的自動櫃員機、智慧型手機與平板電腦等。觸控技術主要可分為電阻式、電容式與紅外線式等等。但對於大部分種類的觸控螢幕而言，當需要更準確偵測出觸控位置，或是螢幕的尺寸越來越大時，所需要的觸控偵測元件越多且良率降低，成本也跟著增加。因此存在一種需求，設計出另一種觸控技術，使其在螢幕尺寸增加時不會增加太多的成本，且同樣可以達到準確偵測觸控位置的功效。本研究之主要目的，在於提供一種可藉由物體陰影而判定觸控位置與觸控時間的影像式觸控方法，可應用在互動式投影裝置上，無需使用大量的觸控偵測元件，不會因尺寸變大而額外增加過多的成本。本論文利用手指或觸控筆與其陰影間的相對關係，來判定手指或觸控筆是否觸碰螢幕。當手指或觸控筆越接近或接觸到螢幕時，其尖端與陰影尖端之距離會越近，甚至遮蔽陰影尖端。藉由追蹤多張畫面之指尖位置，以及指尖與陰影尖端之距離變化，便能判定觸控動作是否發生並定位觸控位置。本論文提出之觸控系統，僅需一台攝影機及一個紅外線光源，搭配互動式投影機，即可偵測觸控動作及定位觸控點；移動方便，投影在任何布幕或白牆即可使用；且不需用力按壓螢幕即可偵測觸控動作。相較於其他大尺寸的觸控面板移動不易，或需要兩台以上的攝影機才可定位觸控點，本論文提出之觸控系統，在建置與成本上具有相當的優勢。

Touch devices have become one of the major elements in today’s most electronic devices. It is commonly used in ATMs, smart phones and tablet PCs. Touch technology can be divided into different types as resistive, capacitive, infrared, and so on. However, with the increase of detection elements, most types of touch screen suffer more cost and lower yield when the accuracy of touch location or larger size is requested. Therefore, it is essential to design a different kind of touch technology with an accurately detection that the cost is not proportional to its size simultaneously. The purpose of this thesis is to provide a kind of touch system that uses the distance between the object and its shadow to detect the touch-timing and position. It can be applied to an interactive projection system without using a lot of touch detecting elements. That is, no additional costs are needed for a great touch screen. This thesis takes advantage of the relative relationship between finger (stylus) and its shadow to determine whether a finger or stylus touches the screen. When a finger or stylus approaches screen, its tip will close to the tip of shadow and even mask it. By tracking the location of the finger with the distance changes between fingertip and its shadow in many frames, the occurrence of touching and its location can be determined. Touch system proposed by this thesis needs only one camera and one IR source, and acts with an interactive projector to detect the occurrence of touching and its location. One of advantages of this touch system is that it needs only one camera. Secondly, it can be moved easily and constructed by any white wall or projection screen. Finally, the touch detection can be done without touching the screen hardly. Comparing to other large-size touch panels which are not easy to move and need two or more cameras to locate touch position, the touch system proposed in this thesis is superior in cost and establishment.