Touched position identification method

A touched position identification method, for identifying a position touched by an object on an optical touch panel, wherein the optical touch panel comprises a first substrate, a second substrate, a display medium between the first substrate and the second substrate, a light guide plate, and a controllable light source, a plurality of optical sensors is disposed on the first substrate, the light guide plate is disposed at one side of the second substrate, and the controllable light source is disposed at a light incident side of the light guide plate, the touched position identification method comprising:

• alternatively performing a turn-on action and a turn-off action on the controllable light source with a predetermined interval;
• obtaining at least a nth image data and a (n+2)th image data corresponding to the turn-on action and a (n+1)th image data and a (n+3)th image data corresponding to the turn-off action by using the optical sensors, wherein n is a natural number;
• and
• performing an operation on the nth image data and the (n+2)th image data corresponding to the turn-on action and the (n+1)th data and the (n+3)th image data corresponding to the turn-off action to obtain a first comparative data and a second comparative data, and identifying the position touched by the object according to the first comparative data and the second comparative data.