Optical touch input device and their driving

There are an optical touch input device, while setting dividing the touch operation to reduce the power consumption of the front of the optical output of a light emitting unit and, and its driving method is disclosed, wherein the optical touch input device, a display panel, a plurality of infrared light emitting elements of two adjacent sides display panel are arranged a lens unit which is disposed on the remaining two adjacent sides of the display panel and reflects emitted light emitted from the infrared light emitting elements of light, a light receiving unit disposed on the two adjacent sides of the display panel, and a touch controller having a touch coordinates calculating unit to calculate an amount of the coordinates of a touch point, and a light emission control unit to the optical outputs of the infrared light emitting elements in an optical output to divide during the contact and in an optical output during non-contact state and to reduce the optical output during non-contact state, includes, contains.