Patent Application
20120146951
1. Technical Field
The present disclosure relates to touch technology, and particularly, to a touch detecting system.
2. Description of the Related Art
A conventional touch detecting system includes a number of optical elements, such as a CCD (Charge Coupled Device, CCD) and/or optical lenses which are arranged in a relatively complex structure in a touch panel or a touch pad. The complex structure of conventional touch detecting systems involves a high cost.
Therefore, there is room for improvement within the art.
The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of a touch detecting system. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views.
Referring to
The at least one optical lens 102 is disposed at the right side of the touch panel 101 and opposite to the point light sources 100a and 100b. The distance between the optical lens 102 and the right side 101b is substantially twice the focal length of the optical lens 102. The at least one optical lens 102 directs the light from the point light sources 100a and 100b to the optical sensor 103. In this embodiment, there are two optical lenses 102a and 102b, which are arranged in a column along the right side 101b. The optical lens 102a is above the optical lens 102b. The focal lengths of the optical lenses 102a and 102b are the same. The optical lenses 102a and 102b are both converging.
The optical sensor 103 is disposed to the right of the optical lens 102, and is separated from the optical lens 102 by a distance equal to the focal length of the optical lens 102. The optical sensor 103 captures an image of the light from the point light sources 100a and 100b. In this embodiment, the optical sensor 103 is a linear CCD. In an alternative embodiment, the optical sensor 103 may be a linear Complementary Metal-Oxide-Semiconductor Transistor (CMOS), or another optical position-sensing detector.
The touch detecting system 10 further includes a processing unit 104 (see
The axes (optical axis 112a and optical axis 112b) of the optical lenses 102a and 102b are parallel. The distance between the optical axis 112a and the dark point 300a′ is L1, and the distance between the optical axis 112b and the dark point 300b′ is L2. In this embodiment, L1 is equal to L2. The distance “D” between the optical axes 112a and 112b is predetermined and stored in the system 10. The processing unit 104 determines L1 and L2 according to a formula Ln=(S-D)/2 where n=1 or 2. F1 and F2 are the respective focal lengths of the optical lenses 102a and 102b. In this embodiment, F1 is equal to F2. Angle α is created between the lightbeams 100a′ and 100b′. The lightbeam 100b′ meets the optical sensor 103 at an angle of β1, and the lightbeam 100a′ meets the optical sensor 103 at an angle of β2. The processing unit 104 determines the angles α and βn according to the following equations where n=1 or 2:
βn=arctan(Fn/Ln) (Equation 1);
α=180°-β1-β2 (Equation 2);
As the lightbeam 100a′ meets the lightbeam 100b′ at a point of 100c, with the dark points 300a′ and 300b′ form a triangle, thus the processing unit 104 is capable of determining the coordinates of the point of contact made by the object 300 according to the angles α, β1, β2, and the distance “S” and “D” using a trilateration method.
It is understood that the present disclosure may be embodied in other forms without departing from the spirit thereof. Thus, the present examples and embodiments are to be considered in all respects as illustrative and not restrictive, and the disclosure is not to be limited to the details given herein.
| Number | Date | Country | Kind |
|---|---|---|---|
| 201010587321.8 | Dec 2010 | CN | national |
