Acoustic wave touch detecting apparatus
View Patent ↗Two groups of inclined lines, which are included in a spurious wave scattering means, are formed at opposite angles with respect to each other in the vicinity of an upper edge of a substrate. The angles of the inclined lines are such that they are close to perpendicular toward the central portion of the substrate, and gradually decrease toward the edges thereof. In a similar manner, two other groups inclined lines, which are also included in the spurious wave scattering means, are formed at opposite angles with respect to each other, with gradually changing angles. The spurious waves that reach these regions are diffuse by the inclined lines, so that they are not propagated to converters (sensors). Three rectangular spurious wave scattering means, formed by inclined lines, inclined at angles other than 45°, also function to diffuse and eliminate spurious waves that propagate along the front surface of the substrate.
1. An acoustic wave contact detecting apparatus comprising:
a substrate having a surface along which acoustic waves propagate;
a mode converting element;
a reflection array for causing the generated acoustic waves to propagate along the surface of the substrate;
a detector for detecting changes in the acoustic wave caused by an object contacting the surface of the substrate; and
a controller for determining the geometric coordinates of the object; wherein:
a diffusing portion for diffusing spurious waves, which are generated accompanying the generation of the acoustic waves, is formed on the substrate, the diffusing portion comprising a plurality of substantially parallel inclined lines, which are densely distributed in the vicinity of an edge of the substrate opposite that at which the mode converting element is provided.
2. An acoustic wave contact detecting apparatus as defined in claim 1 , wherein:
the diffusing portion is formed of the same material as that of the substrate.
3. An acoustic wave contact detecting apparatus as defined in claim 1 , wherein:
the mode converting elements and the diffusing portion are formed by printing.
4. An acoustic wave contact detecting apparatus as defined in claim 1 , wherein:
the mode converting elements and the diffusing portion are formed by etching.