Touchscreen system with simplified mechanical touchscreen design using capacitance and acoustic sensing technologies, and method therefor
View Patent ↗A simplified touch screen system that can sense when an object is held in continuous direct or indirect contact with a transparent substrate of the touch screen system as well as determine a location (e.g., X, Y coordinates) of the object in relation to the transparent substrate. The touch screen system employs capacitance technology to sense whether the object is held in contact with the transparent substrate and acoustic sensing technology to determine a position of the object that is contacting the transparent substrate. The touch screen system requires a reduced number of shielding and isolation layers to be deposited upon the transparent substrate, partially because the touch screen system utilizes a bezel associated with an underlying display to provide shielding against electromagnetic radiation emitted by the display.
1. A touch screen system for an electronic device having a power source and a touch screen control board, comprising:
a transparent substrate having an external surface and an internal surface, the transparent substrate for receiving a contact from an object upon the external surface;
deposited layers arranged about a perimeter of the internal surface of the transparent substrate, the deposited layers consisting of:
a conductive layer deposited upon the internal surface of the transparent substrate, wherein the conductive layer forms a pattern of conductive traces; and
an isolation layer deposited upon the conductive layer;
one or more acoustic sensors associated with the transparent substrate, wherein the acoustic sensors receive an acoustic wave generated by the contact and convert the acoustic wave to an electronic signal, and wherein the acoustic sensors are electrically connected through a first one of the conductive traces; and
a plurality of capacitive sensors associated with the transparent substrate, each of the capacitive sensors comprising a first electrode that is spaced a distance from a second electrode, wherein each of the first electrodes is both formed by and electrically connected through a second one of the conductive traces and each of the second electrodes is electrically connected through a third one of the conductive traces, wherein the isolation layer is disposed between the first and second electrodes of each of the capacitive sensors, and wherein the contact of the object causes a capacitive change in the capacitive sensors.
2. The touch screen system as defined in claim 1 , further comprising a processor for monitoring the electronic signal and the capacitive change, wherein the processor analyzes the electronic signal to determine a location of the object upon the transparent substrate and the capacitive change to determine whether the object remains in continuous contact with the transparent substrate.
3. The touch screen system as defined in claim 1 , further comprising one flexible printed circuit (FPC) connector, wherein the one FPC connector electrically connects each of the conductive traces with the touch screen control board to thereby electrically interconnect both the one or more acoustic sensors and the plurality of capacitive sensors to the touch screen control board.
4. The touch screen system as defined in claim 1 , further comprising a compressible gasket situated between the first and second electrodes of each of the capacitive sensors.
5. The touch screen system as defined in claim 4 , wherein the compressible gasket is formed of a double-sided foam tape.
6. The touch screen system as defined in claim 1 , wherein one of the capacitive sensors is positioned at an approximate middle point along each edge of the internal surface of the transparent substrate.
7. The touch screen system as defined in claim 1 , wherein each of the second electrodes comprises a first electrically conductive area deposited upon a first side of a flexible printed circuit (FPC) strip.
8. The touch screen system as defined in claim 7 , wherein the FPC strip comprises a second side having a second electrically conductive area, and wherein the second electrically conductive area is grounded through a fourth one of the conductive traces such that the second electrically conductive area provides electromagnetic radiation shielding.
9. The touch screen system as defined in claim 8 , further comprising a plurality of access apertures extending through the isolation layer, wherein each second electrically conductive area is electrically connected to the fourth one of the conductive traces via a different one of the plurality of access apertures.
10. The touch screen system as defined in claim 9 , wherein each first electrically conductive area is electrically connected to the third one of the conductive traces via a different one of the plurality of access apertures.
11. The touch screen system as defined in claim 1 , further comprising:
a display having an active display area; and
a conductive bezel framing a perimeter of the active display area, wherein the conductive bezel shields the acoustic sensors, the capacitive sensors, and the conductive traces from electromagnetic radiation emitted from the display.
12. The touch screen system as defined in claim 1 , wherein the acoustic wave is a bending wave.
13. The touch screen system as defined in claim 1 , further comprising a plurality of access apertures extending through the isolation layer, wherein each second electrode is electrically connected to the third one of the conductive traces via a different one of the plurality of access apertures.
14. The touch screen system as defined in claim 1 , wherein the first and second electrodes of each capacitive sensor are spaced in a direction extending away from the internal surface of the transparent substrate.
15. A method of analyzing a contact from an object upon a touch screen system, comprising:
providing a transparent substrate having external and internal surfaces;
depositing layers, other than shielding layers, on the internal surface of the transparent substrate, the depositing comprising:
depositing a layer of conductive material to form an annular pattern of conductive traces about a perimeter of the internal surface of the transparent substrate, wherein the conductive traces form a plurality of first electrodes; and
depositing a layer of insulating material upon the layer of conductive material;
connecting a plurality of second electrodes to the conductive traces, wherein the insulating material spaces each of the second electrodes a distance from one of the first electrodes such that each pair of the first and the second electrodes forms a capacitive sensor, and wherein the contact of the object causes a capacitive change in the capacitive sensors; and
connecting one or more acoustic sensors to the conductive traces, wherein the acoustic sensors receive an acoustic wave generated by the contact from the object and convert the acoustic wave to an electronic signal.
16. The method as defined in claim 15 , further comprising:
associating a processor with the conductive traces; and
upon the contact of the object with the external surface of the transparent substrate, using the processor to:
monitor the electronic signal to determine a location of the object upon the transparent substrate; and
monitor the capacitive change to determine whether the object remains in continuous contact with the transparent substrate.
17. The method as defined in claim 15 , wherein each of the second electrodes comprises a first electrically conductive area deposited upon a first side of a flexible printed circuit (FPC) strip.
18. The method as defined in claim 17 , wherein the FPC strip comprises a second side having a second electrically conductive area, and wherein the method further comprises:
grounding the second electrically conductive area through the conductive traces such that the second electrically conductive area provides electromagnetic radiation shielding.
19. The method as defined in claim 15 , further comprising:
associating a display and a conductive bezel with the transparent substrate, wherein the display has an active display area and the conductive bezel frames a perimeter of the active display area such that the conductive bezel aligns with the layer of conductive material; and
grounding the conductive bezel such that the bezel shields the acoustic sensors, the capacitive sensors, and the conductive traces from electromagnetic radiation emitted from the display.
20. The method as defined in claim 19 , wherein the grounding comprises connecting the conductive bezel to ground through the conductive traces.
21. The method as defined in claim 15 , further comprising:
connecting each of the conductive traces to a touch screen control board through a flexible printed circuit (FPC) connector.
22. A touch screen system for an electronic device having a power source and a touch screen control board, comprising:
a transparent substrate having an external surface and an internal surface, the transparent substrate for receiving a contact from an object upon the external surface;
a pattern of conductive traces arranged about a perimeter of the internal surface of the transparent substrate, wherein the conductive traces are deposited directly upon the internal surface of the transparent substrate;
an isolation layer deposited upon the conductive traces;
one or more acoustic sensors associated with the transparent substrate, wherein the acoustic sensors receive an acoustic wave generated by the contact and convert the acoustic wave to an electronic signal, and wherein the acoustic sensors are electrically connected through a first one of the conductive traces; and
a plurality of capacitive sensors associated with the transparent substrate, each of the capacitive sensors comprising a first electrode that is spaced a distance from a second electrode, wherein each of the first electrodes is both formed by and electrically connected through a second one of the conductive traces and each of the second electrodes is electrically connected through a third one of the conductive traces, wherein the isolation layer is disposed between the first and second electrodes of each of the capacitive sensors, and wherein the contact of the object causes a capacitive change in the capacitive sensors.
23. The touch screen system as defined in claim 22 , further comprising:
a display having an active display area; and
a conductive bezel that frames a perimeter of the active display area, wherein the conductive bezel substantially abuts the isolation layer, and wherein the conductive bezel is connected to ground.
24. The touch screen system as defined in claim 22 , further comprising one flexible printed circuit (FPC) connector, wherein the FPC connector electrically interconnects each of the conductive traces with the touch screen control board to thereby electrically interconnect both the one or more acoustic sensors and the plurality of capacitive sensors to the touch screen control board.
25. The touch screen system as defined in claim 22 , further comprising a processor for monitoring the electronic signal and the capacitive change, wherein the processor analyzes the electronic signal to determine a location of the object upon the transparent substrate and the capacitive change to determine whether the object remains in continuous contact with the transparent substrate.
26. The touch screen system as defined in claim 22 , wherein each second electrode is electrically connected to the third one of the conductive traces via an access aperture extending through the isolation layer.