Abstract:
A charge pump that can be configured to operate in a first mode and a second mode is disclosed. The charge pump can comprise a charging capacitor coupled to a first node and configured to transfer a first DC voltage to the first node. The charge pump can also comprise a first output node and a second output node coupled to the first node. During the first mode, the first output node can be configured to output a second DC voltage based on the first DC voltage, and the second output node can be configured to output a third DC voltage based on the first DC voltage. During the second mode, the first output node can be configured to output the second DC voltage, and the second output node can be configured to output an AC voltage, the AC voltage being offset by the third DC voltage.
Abstract:
A sense amplifier can be designed with a series variable resistance circuit to dynamically adjust an input resistance in series with the sense amplifier for stability during the different operating modes. In some examples, a switchable resistor can be switched into the input path of the sense amplifier for stability when required by increased capacitive loading of the sense electrodes, and can be switched out of the input path of the sense amplifier when unnecessary for stability. In some examples, an adjustable resistor can be coupled to and in series with the input of the sense amplifier. The resistance of the adjustable resistor can be tuned to stabilize the sense amplifier during operating modes having increased capacitive loading from the sense electrodes and can be minimized when additional input resistance is unnecessary for stability.
Abstract:
Disclosed herein are liquid-crystal display (LCD) touch screens that integrate the touch sensing elements with the display circuitry. The integration may take a variety of forms. Touch sensing elements can be completely implemented within the LCD stackup but outside the not between the color filter plate and the array plate. Alternatively, some touch sensing elements can be between the color filter and array plates with other touch sensing elements not between the plates. In another alternative, all touch sensing elements can be between the color filter and array plates. The latter alternative can include both conventional and in-plane-switching (IPS) LCDs. In some forms, one or more display structures can also have a touch sensing function. Techniques for manufacturing and operating such displays, as well as various devices embodying such displays are also disclosed.
Abstract:
Systems and processes for stimulating a touch sensor panel using orthogonal frequencies are provided. In one example process, the drive lines of the touch sensor panel can be stimulated with stimulation signals having orthogonal frequencies. The orthogonal frequencies can be separated by a frequency that is inversely proportional to an integration time of the touch sensor panel. The touch signals generated in response to the stimulation signals can be amplified, converted into digital form, demodulated using the orthogonal frequencies, and integrated over the integration time. Integrating the demodulated signals over a length of time that is inversely proportional to the frequency spacing between the orthogonal frequencies reduces or eliminates interference in the touch signals caused by the stimulation signals having different frequencies.