Acoustic touch sensor
A touch sensor comprises a substrate capable of propagating acoustic waves. The substrate includes a first surface having a touch sensitive region. A transducer is formed on the substrate. The transducer comprises a piezoelectric element which is thermally cured after being formed on the substrate. The transducer is configured for at least one of generating acoustic waves and detecting acoustic waves. Alternatively, the transducer may include a strip comprising the piezoelectric element.
1 . A touch sensor comprising:
a substrate capable of propagating acoustic waves, the substrate including a first surface having a touch sensitive region; and
a transducer formed on the substrate, the transducer comprising a piezoelectric element being thermally cured after being formed on the substrate, the transducer being configured for at least one of generating acoustic waves and detecting acoustic waves.
2 . The touch sensor of claim 1 , wherein the piezoelectric element is formed on the substrate by one of screen printing and pad printing.
3 . The touch sensor of claim 1 , the substrate further comprising a second surface parallel to the first surface, the transducer further comprising grating elements formed on the first surface, the piezoelectric element being formed on the second surface opposite the grating elements.
4 . The touch sensor of claim 1 , the transducer further comprising grating elements formed on the first surface, the piezoelectric element being formed over the grating elements.
5 . The touch sensor of claim 1 , the transducer further comprising:
a first conductive layer formed on the substrate;
a second layer formed over the first conductive layer, the second layer comprising the piezoelectric element; and
a third conductive layer being formed over the second layer, the first and third conductive layers being interconnected with first and second electrical connections, respectively.
6 . The touch sensor of claim 1 , the transducer further comprising:
a first layer formed on the substrate, the first layer being interconnected with a ground connection;
a second layer formed over the first layer, the second layer comprising the piezoelectric element; and
a third conductive layer formed over the second layer, the third conductive layer comprising first and second electrodes, the first and second electrodes being interconnected with first and second electrical connections.
7 . The touch sensor of claim 1 , wherein the substrate being an external layer of a display device.
8 . The touch sensor of claim 1 , the transducer further comprising:
a first conductive layer formed on the substrate;
a second layer formed over the first conductive layer, the second layer comprising the piezoelectric element;
a third conductive layer formed over the second layer, the first and third conductive layers being interconnected with electrical connections; and
a fourth modulation layer comprising periodically applied material being formed over the third conductive layer.
9 . A touch sensor comprising:
a substrate capable of propagating acoustic waves, the substrate including a first surface having a touch sensitive region; and
a transducer configured for at least one of generating acoustic waves and receiving acoustic waves, the transducer including a strip comprising a piezoelectric material, the strip being attached to the substrate.
10 . The touch sensor of claim 9 , the piezoelectric material comprising a polymer piezo material.
11 . The touch sensor of claim 9 , the strip further comprising at least two layers of conductive material, the piezoelectric material being formed between two layers of the at least two layers of conductive material.
12 . The touch sensor of claim 9 , the first surface further comprising a touch area having a perimeter, the substrate further comprising a second surface being parallel to the first surface, the touch sensor further comprising a grating transducer formed on the first surface within the perimeter, the strip being attached to the second surface opposite the grating transducer.
13 . A method for forming a transducer on a touch sensor substrate, the substrate including a first surface having a touch sensitive region, the method comprising:
applying a conductive layer to the substrate;
applying a piezoelectric layer to the substrate, the piezoelectric layer covering at least a portion of the first conductive layer; and
thermally curing the piezoelectric layer.
14 . The method of claim 13 , further comprising applying a second conductive layer to the substrate, the second conductive layer covering at least a portion of the piezoelectric layer.
15 . The method of claim 13 , further comprising:
applying a second conductive layer to the substrate; and
applying first and second voltages to the conductive layer and the second conductive layer, respectively, to pole the piezoelectric layer.
16 . The method of claim 13 , wherein the applying a piezoelectric layer step further comprising screen printing the piezoelectric material.
17 . The method of claim 13 , further comprising forming grating elements on the substrate by removing material from the substrate, the applying steps further comprising applying the conductive layer and the piezoelectric layer over the grating elements.
18 . The method of claim 13 , further comprising:
forming conductive traces on the substrate; and
interconnecting the conductive traces with the conductive layer to provide electrical signals to the conductive layer.
19 . The method of claim 13 , wherein the piezoelectric material comprising a sol-gel material.
20 . The method of claim 13 , wherein the substrate further comprising a sidewall intersecting the first surface at an edge, the sidewall being substantially perpendicular to the first surface.