Optical touch system with display screen

An optical touch system, comprising:

• a display screen comprising a contact surface;
• an infrared light source configured for emitting infrared light to cover the contact surface;
• a linear infrared sensor having a sensing surface with a lengthwise direction thereof parallel to the contact surface, the linear infrared sensor configured for capturing an image of the contact surface with an infrared portion representing a touch area of a contact object, the image having an aspect ratio greater than that of the contact surface;
• a processor configured for determining the touch location of the contact object based on the aspect ratio of the image, the aspect ratio of the contact surface, the location of the infrared portion on the image, the area of the infrared portion on the image, and the area of the touch portion of the contact object on the contact surface;
• and
• a controller configured for executing an instruction according to the determined location of the contact object on the contact surface.