Capacitive pressure sensor and method for the same
A capacitive pressure sensor includes an upper substrate having a first face and a second face opposite to the first face, a first electrode layer with a plurality of first sensing electrodes, a second electrode layer having at least one second sensing electrode, a dielectric layer arranged between the first and the second electrode layers, and a capacitance sensing circuit. In pressure sensing operation, the capacitance sensing circuit sends a capacitance-exciting signal to the at least one second sensing electrode and obtains a pressure sensing signal from the second sensing electrode.
1. A capacitive pressure sensor comprising:
an upper substrate having a first face and a second face opposite to the first face;
a first electrode layer arranged on the second face and having a plurality of first sensing electrodes;
a second electrode layer having at least one second sensing electrode, the first electrode layer placed between the upper substrate and the second electrode layer;
a dielectric layer arranged between the first electrode layer and the second electrode layer; and
a capacitance sensing circuit configured to send a capacitance-exciting signal to the at least one second sensing electrode and obtain a pressure sensing signal from the second sensing electrode, thus performing pressure sensing,
wherein the capacitance sensing circuit is configured to send, sequentially or randomly, a counter-exciting signal to at least one chosen first sensing electrode, the chosen first sensing electrode corresponding to the at least one second sensing electrode.
2. The capacitive pressure sensor in claim 1 , wherein the dielectric layer comprises an elastic gel material, where the elastic gel material is compressively deformed under pressure and restores to original shape and volume if pressure is not present.
3. The capacitive pressure sensor in claim 1 , wherein the counter-exciting signal is a DC reference voltage or a time-varying signal with phase opposite to that of the capacitance-exciting signal.
4. The capacitive pressure sensor in claim 1 , wherein the capacitance sensing circuit is configured to send sequentially or randomly a signal with phase same with the capacitance-exciting signal to at least one of non-chosen first sensing electrode.
5. The capacitive pressure sensor in claim 1 , wherein the capacitance-exciting signal is a time-varying signal or a current source.
6. The capacitive pressure sensor in claim 5 , wherein the time-varying signal is a sinusoidal wave signal, a square wave signal, a triangular wave signal or a trapezoidal wave signal.
7. The capacitive pressure sensor in claim 1 , wherein the capacitance sensing circuit is a self-capacitance sensing circuit.
8. The capacitive pressure sensor in claim 1 , wherein the upper substrate is a glass substrate, a polymer substrate or a hard coating layer.
9. The capacitive pressure sensor in claim 1 , further comprising a lower substrate arranged toward a side of the second electrode layer opposite to the dielectric layer, the lower substrate is a glass substrate or a polymer substrate.
10. The capacitive pressure sensor in claim 9 , wherein the lower substrate is a color filter of a display panel.
11. A method for performing a capacitive pressure sensing, comprising:
providing a capacitive pressure sensor comprising: an upper substrate having a first electrode layer on a face of the upper substrate and having a plurality of first sensing electrodes; a second electrode layer having at least one second sensing electrode, and a dielectric layer arranged between the first electrode layer and the second electrode layer, the dielectric layer compressively deformed under pressure and restoring to original shape and volume if pressure is not present, and a capacitance sensing circuit;
sending a capacitance-exciting signal to the at least one second sensing electrode and obtaining a pressure sensing signal from the second sensing electrode, thus performing pressure sensing; and
sequentially or randomly sending a counter-exciting signal to at least one chosen first sensing electrode, the chosen first sensing electrode corresponding to the at least one second sensing electrode.
12. The method in claim 11 , wherein the capacitance-exciting signal is a time-varying signal.
13. The method in claim 12 , wherein the time-varying signal is a sinusoidal wave signal, a square wave signal, a triangular wave signal or a trapezoidal wave signal.
14. The method in claim 11 , wherein the counter-exciting signal is a DC reference voltage or a time-varying signal with phase opposite to that of the capacitance-exciting signal.
15. The method in claim 14 , wherein the DC reference voltage is a ground signal of zero volt.
16. The method in claim 11 , further comprising sending a signal with phase same as the capacitance-exciting signal to at least one of non-chosen first sensing electrodes.
17. The method in claim 11 , wherein the capacitance sensing circuit is a self-capacitance sensing circuit.