Touch screen driving
A touch sensor controller according to some implementations includes a reference signal generator generating a reference signal based on an input image signal and a receiver connected to a touch electrode, receiving a sensing signal from the touch electrode, and generating an output signal based on difference between the reference signal and the sensing signal.
1 . A touch sensor controller comprising:
a reference signal generator configured to generate a reference signal based on an input image signal; and
a receiver connected to a touch electrode, the receiver configured to receive a sensing signal from the touch electrode and generate an output signal based on a difference between the reference signal and the sensing signal.
2 . The touch sensor controller of claim 1 , wherein the reference signal generator is configured to:
receive a selection signal generated based on the input image signal;
generate the reference signal based on the selection signal; and
control at least one of a damping factor or a settling time of the reference signal using a variable capacitor and a variable resistor.
3 . The touch sensor controller of claim 2 , wherein the reference signal generator comprises:
a first amplifier having a first input terminal, a second input terminal, and an output terminal, wherein the first amplifier is configured to
receive the selection signal from the first input terminal,
receive a direct current (DC) voltage from the second input terminal, and
generate the reference signal based on the selection signal and the DC voltage;
a first capacitor having a first terminal to which the selection signal is applied and a second terminal to which the first input terminal of the first amplifier is connected;
a second capacitor having a third terminal to which the first input terminal is connected and a fourth terminal to which the output terminal of the first amplifier is connected; and
a resistor connected in parallel with the second capacitor.
4 . The touch sensor controller of claim 3 , comprising:
a reference driver configured to receive a conversion signal generated based on the input image signal and generate the selection signal based on the conversion signal; and
a converter configured to perform a data processing operation on the input image signal to generate the conversion signal.
5 . The touch sensor controller of claim 4 , wherein the reference driver comprises:
a decoder configured to receive a plurality of gamma voltages and select one gamma voltage among the plurality of gamma voltages based on the conversion signal; and
a second amplifier configured to amplify the selected one gamma voltage to generate the selection signal.
6 . The touch sensor controller of claim 4 , wherein the converter is configured to perform a sum operation, a scaling operation, and an inversion operation on the input image signal to generate the conversion signal.
7 . The touch sensor controller of claim 6 , wherein the converter is configured to perform the scaling operation using a scaling coefficient that is a ratio of (i) a number of reference drivers to (ii) a number of source drivers generating a plurality of source signals based on the input image signal.
8 . The touch sensor controller of claim 7 , wherein a capacitance of the first capacitor is an equivalent parasitic capacitance divided by the ratio, and wherein the equivalent parasitic capacitance is a capacitance between (i) a plurality of source lines to which the plurality of source signals are applied and (ii) a cathode layer of a touch screen device controlled by the touch sensor controller.
9 . The touch sensor controller of claim 3 , wherein the first amplifier is configured to receive half of a driving voltage from the second input terminal.
10 . A touch screen driving circuit comprising:
a display driving circuit configured to generate a plurality of source signals based on an input image signal and provide the plurality of source signals to a plurality of source lines; and
a touch sensor controller configured to
receive a plurality of sensing signals from a plurality of touch electrodes,
generate, based on the input image signal, a reference signal having the same waveform as a waveform of a noise signal transmitted to the plurality of touch electrodes by the plurality of source signals, and
generate a plurality of touch signals based on the plurality of sensing signals and the reference signal.
11 . The touch screen driving circuit of claim 10 , wherein the touch sensor controller comprises:
a plurality of receivers configured to receive the plurality of sensing signals from a plurality of receiving electrodes and configured to, based on the reference signal, remove respective noise signals from the plurality of sensing signals to thereby generate the plurality of touch signals.
12 . The touch screen driving circuit of claim 11 , further comprising:
a converter configured to perform a data processing operation on the input image signal to generate a conversion signal; and
a reference driver configured to receive a plurality of gamma voltages and the conversion signal and generate a selection signal based on the plurality of gamma voltages and the conversion signal,
wherein the touch sensor controller is configured to generate the reference signal based on the selection signal.
13 . The touch screen driving circuit of claim 10 , wherein the touch sensor controller comprises:
a first reference signal generator configured to generate a first reference signal based on a first selection signal generated based on the input image signal;
a second reference signal generator configured to generate a second reference signal based on a second selection signal generated based on the input image signal; and
a plurality of receivers configured to
receive the plurality of sensing signals from a plurality of receiving electrodes, and
remove respective noise signals from the plurality of sensing signals based on the first reference signal or the second reference signal, to generate the plurality of touch signals.
14 . The touch screen driving circuit of claim 13 , comprising:
a first converter configured to perform a first data processing operation on a first input image signal to generate a first conversion signal;
a first reference driver configured to receive a plurality of gamma voltages and the first conversion signal, and generate the first selection signal based on the plurality of gamma voltages and the first conversion signal;
a second converter configured to perform a second data processing operation on a second input image signal to generate a second conversion signal; and
a second reference driver configured to receive the plurality of gamma voltages and the second conversion signal, and generate the second selection signal based on the plurality of gamma voltages and the second conversion signal.
15 . The touch screen driving circuit of claim 10 , wherein the display driving circuit is configured to generate the plurality of source signals in synchronization with a horizontal synchronization signal, and
wherein the touch sensor controller is configured to
generate the reference signal in synchronization with the horizontal synchronization signal, and
generate the plurality of touch signals based on the plurality of sensing signals and the reference signal within a period of the horizontal synchronization signal.
16 . The touch screen driving circuit of claim 10 , wherein the plurality of touch electrodes are configured to output the plurality of sensing signals based on a mutual capacitance between the plurality of touch electrodes and a plurality of driving electrodes to which one or more driving signals are applied.
17 . A method of driving a touch screen, comprising:
receiving an input image signal;
generating a conversion signal by processing the input image signal;
selecting a gamma voltage based on the conversion signal;
generating a reference signal by amplifying the selected gamma voltage; and
removing a noise signal from a sensing signal based on the reference signal.
18 . The method of claim 17 , wherein generating the conversion signal comprises:
generating a first processing signal by adding together the input image signal;
generating a second processing signal by scaling the first processing signal; and
generating the conversion signal by inverting the second processing signal.
19 . The method of claim 18 , wherein generating the second processing signal comprises:
determining a scaling coefficient based on a ratio between a number of source drivers and a number of reference drivers; and
generating the second processing signal by scaling the first processing signal based on the scaling coefficient.
20 . The method of claim 17 , wherein generating the reference signal comprises:
controlling at least one of a damping factor or a settling time of the reference signal such that the reference signal is equal to the noise signal.