Multiple-input touch panel and method for gesture recognition

A method for recognizing at least one gesture on a touch panel with a first optical unit, the method comprising

• obtaining a plurality of possible touch points according to intensities of light detected from a first optical element and retro-reflected by a second or a third optical element;
• selecting one pair of touch points from the possible touch points;
• locating new positions of the selected pair of touch points by finding the most adjacent points thereof;
• and
• recognizing the at least one gesture according to changes to distance and slope between the pair of touch points and the new positions of the selected pair of touch points,
• the step of obtaining a plurality of possible touch points comprising:
• generating a touch signal if intensity of light at a certain angle is less than a first threshold;
• and
• obtaining the possible touch points according to the intersection of paths of the light generating two touch signals.

A method of calculating misalignment of an optical element of a touch panel, the touch panel comprising a first, a second, a third and a fourth edge, the optical element being positioned at the first edge, the method comprising the steps of

• touching a first point at the first edge at a predetermined distance from the fourth edge adjacent to the first and the third edges and deriving a first angle between the third edge and a path connecting the first optical unit emitting light and the first point;
• touching a second point at the third edge at a distance twice the predetermined distance from the fourth edge, and deriving a second angle between the third edge and the path between the optical unit emitting light and a point at the optical element reflecting the light;
• and
• determining an angle of misalignment of the optical element by a difference between the first and second angles.