CAPACITIVE TOUCH PANEL DEVICE
The invention provides a touch panel device comprising, and arranged above each other in a downward direction, a cover layer for use as a touch surface, a sensor layer comprising a plurality of sensing elements, the sensing elements being arranged to register capacitance, characterized in that between the cover layer and the sensor layer is an electrically-resistive layer, electrically resistive layer being a electrically non-insulating layer and having an electrical resistance is provided, wherein the electrical resistance of the electrically-resistive layer is lower than the electrical resistance of the cover layer and higher than the electrical resistance of the sensing elements. The electrically-resistive layer can have a resistance suitable for causing, in response to a touch event above a center of a central sensing element, a detectable change in the capacitance as measured by at least two sensing elements adjacent to the central sensing element.
1 . A touch panel device ( 1 ), comprising:
a cover layer ( 2 ) for use as a touch surface;
a sensor layer comprising a plurality of sensing elements, the sensing elements being arranged to register capacitance;
a electrically-resistive layer is between the cover layer and the sensor layer, wherein the electrically-resistive layer is an electrically non-insulating layer and an electrical resistance of the electrically-resistive is provided;
wherein the electrical resistance of the electrically-resistive layer is lower than the electrical resistance of the cover layer and higher than the electrical resistance of the sensing elements.
2 . A touch panel device as claimed in claim 1 , wherein the electrically-resistive layer has a electrical resistance suitable for causing, in response to a touch event above a center of a central sensing element, a detectable change in the capacitance as measured by at least two sensing elements adjacent to the central sensing element.
3 . A touch panel device as claimed in claim 2 , wherein the electrically-resistive layer has a sheet resistance between 1 and 10,000 MOhm/sq.
4 . A touch panel device as claimed in claim 3 , wherein the sheet resistance of the electrically-resistive layer is preferably between 20 and 5000 MOhm/sq.
5 . A touch panel device as claimed in claim 4 , wherein the sheet resistance of the electrically-resistive layer is even more preferably between 100 and 1000 MOhm/sq.
6 . A touch panel device as claimed in claim 1 , wherein the electrically-resistive layer is formed as a high-resistive ITO layer.
7 . A touch panel device as claimed in claim 1 , wherein the electrically-resistive layer is formed on the cover layer.
8 . A touch panel device as claimed in claim 1 , wherein a sub-layer is provided between the cover layer and the sensor layer.
9 . A touch panel device as claimed in claim 8 , wherein the electrically-resistive layer is a deposited layer on the sub-layer.
10 . A touch panel device as claimed in claim 8 , wherein the sub-layer comprises at least one of a polarizer layer, an anti-splinter film, an airgap layer, and an optical clear adhesive layer.
11 . A touch panel device as claimed in claim 8 , wherein the sub-layer is also arranged as an anti-static layer.
12 . A touch panel device as claimed in claim 1 , wherein the sensor layer is attached on a substrate layer.
13 . A touch panel device as claimed in claim 12 , the substrate layer comprises:
a reference electrode layer attached to the side opposite the side of the substrate layer to which the sensor layer is attached.
14 . A touch panel device as claimed in claim 1 , wherein the touch panel device comprises a display module and the cover layer is formed of a transparent material.
15 . A touch panel device as claimed in claim 14 , wherein a reference electrode layer is provided on the display module.
16 . A touch panel device as claimed in claim 15 , wherein the reference electrode layer is further provided inside the display module.
17 . A touch panel device as claimed in claim 1 , wherein the touch panel preferably comprises a processor which is arranged to the register capacitance changes of each of the plurality of sensing elements, wherein the processor is adapted to determine a touch location by calculating a weighted location average of capacitance changes registered by a plurality of the touch panel devices.