Acoustic touch sensor with laminated substrate
View Patent ↗The present invention is directed to a multilayer substrate for use in touchscreen and touch sensor applications. The substrate, including a microsheet, a polymer sheet, and a plate supports the propagation of acoustic waves, including Love waves and Rayleigh-like waves. The microsheet and plate may be fabricated from glass, metal, or other suitable materials depending on the desired application for the touchscreen. The polymer sheet may be fabricated from polystyrene, polyacrylates, polyether sulfones, or polycyclic olefins. The disclosed touchscreen substrates are thin but durable and have increased touch sensitivity with decreased sensitivity to water and other surface contaminants.
1. An acoustic touch sensor substrate comprising:
a first shear supporting sheet comprising an upper surface and a lower surface, said upper surface comprising a touch surface;
a shear supporting plate; and
a second flexible sheet (i) comprising a shear supporting polymer positioned between said first sheet and said plate, and (ii) having a thickness of about 10 to 100 microns.
2. An acoustic touch sensor substrate comprising:
a first shear supporting sheet comprising an upper surface and a lower surface, said upper surface comprising a touch surface;
a shear supporting plate; and
a second flexible sheet comprising a shear supporting polymer (i) positioned between said first sheet and said plate and (ii) having a glass transition temperature above about 260° K.
3. The acoustic touch sensor substrate of claim 2 , wherein said shear supporting polymer is selected from the group consisting of polystyrene, polyacrylate, polycyclic olefins, polyether sulfones, and mixtures thereof.
4. An acoustic touch sensor substrate comprising:
a first shear supporting sheet comprising an upper surface and a lower surface, said upper surface comprising a touch surface;
a shear supporting plate; and
a second flexible sheet comprising a shear supporting polymer positioned between said first sheet and said plate,
said first sheet and the plate having bulk shear wave velocities, and the bulk shear wave velocity of the sheet being slower than the bulk shear wave velocity of the plate.
5. The acoustic touch sensor substrate of claim 4 , wherein the bulk shear wave velocity of said first sheet is more than about 5% slower than the bulk shear wave velocity in said plate.
6. An acoustic touch sensor substrate comprising:
a first shear supporting sheet comprising (i) an upper surface and a lower surface, said upper surface comprising a touch surface, and (ii) glass having a thickness of about 100 microns;
a shear supporting plate having a thickness greater than about 0.5 mm and comprising glass having a thickness greater than about 0.5 mm; and
a second flexible sheet comprising (i) a shear supporting polymer positioned between said first sheet and said plate and (ii) polystyrene having a thickness of about 32 microns.
7. An acoustic touch sensor substrate comprising:
a first shear supporting sheet having a thickness less than about 300 microns;
a shear supporting plate having a thickness less than about 12 mm; and
a second sheet comprising a shear supporting polymer disposed between said first sheet and said plate, said second sheet having a thickness less than about 100 microns.
8. An acoustic touch system comprising:
a touch substrate comprising:
a first sheet having a shear supporting touch surface;
a shear supporting plate; and
a second flexible sheet comprising a shear supporting polymer positioned between said first sheet and said plate; and
electronic circuitry which corrects for dispersion effects.
9. The acoustic touch system of claim 8 , wherein the electronic circuitry corrects the dispersion effects with digital signal processing.
10. An acoustic touch sensor substrate comprising
a first shear supporting sheet comprising an upper surface and a lower surface, said upper surface comprising a touch surface;
a shear supporting plate; and
a second flexible sheet comprising a shear supporting polymer positioned between said first sheet and said plate,
said substrate supporting Rayleigh waves operating at a frequency having a dispersion parameter less than or equal to one and only one surface-bound Rayleigh wave existing at the desired operating frequency.
11. An acoustic touch sensor substrate comprising:
a first shear supporting sheet comprising an upper surface and a lower surface, said upper surface comprising a touch surface;
a shear supporting plate; and
a second flexible sheet comprising a shear supporting polymer positioned between said first sheet and said plate,
said substrate supporting Rayleigh waves operating at a frequency (i) having a dispersion parameter less than or equal to one and (ii) being within about 30% of a cut-off frequency of a second Rayleigh wave.