The ClearPad transparent capacitive touch sensor from Synaptics features high noise immunity and low power consumption.
Synaptics Inc. (Santa Clara, CA, U.S.; www.synaptics.com) offers the ClearPad touchscreen series—a complete portfolio of single-, dual-, and multi-finger touch sensing solutions—based on its patented projected capacitive sensing technology. According to Binay Bajaj, ASIC strategic marketing manager at Synaptics, this technology utilizes an array or a matrix of electrodes spanning the touch panel’s sensing region. A finger touch changes the capacitance of multiple electrodes simultaneously, not just one at a time. As a result, the position of the finger(s) can be determined at a much higher resolution than the electrode spacing through interpolation.
To help customers easily integrate gestures with the devices they control, the supplier offers the Enhanced Gesture Recognition (EGR) technology as optional functionality. “EGR gives customers the option to enable single-finger gestures such as tap, double tap, press, and flick, as well as multi-finger gestures like pinch, directly from Synaptics' touch module. No additional recognition software is required on the host processor to implement these gestures. This approach lowers host processor resource requirements and ensures that gestures are implemented using Synaptics' proven pattern-recognition technology,” says Bajaj.
All of the firm’s ClearPad touchscreen products feature high noise immunity, as noise filtering is addressed at various levels. “There is noise filtering in the touch controller ASIC where the hardware actively filters high frequency and low frequency noise and also in the firmware, which not only has advanced filtering algorithms, but also constantly averages the touch response to filter out the noisy outliers,” explains Bajaj. “At the system level, there is ground shielding employed, which blocks the noise to enter into the touch controller.”
As for power management, the supplier has employed various power saving modes in the touch controller hardware and firmware. For example, “the firmware constantly monitors the activity and quickly goes into doze mode or sleep mode if the device is not used,” says Bajaj.
ClearPad sensors work with all the LCD technologies available in the market today, including the active matrix TFT (thin film transistor) LCD. Due to its high response times, low power and low cost, Bajaj says the Amorphous Silicon (or a-si) TN (Twisted Nematic) TFT LCD is the most common type of TFT LCD for CE applications.