Touch and Display Integration for automotive HMI

Current automotive touch and display modules are dominated by discrete capacitive or resistive touch screens for HMI. There is growing demand for an efficient industrial design of a display with high light transmittance and low reflectance which also meets the strict EMC requirements in automotive market. The integration of touch and display ICs to a single die called Touch Display Driver IC (TDDI) combined with the integration of the sensor into the display electrodes (full in-cell) is a trend and panels are becoming available now from multiple display manufacturers. The capacitive touch sensing derived from electrodes integrated into a TFT display with a TDDI has been proven in the consumer market and dedicated research has resulted in technology advances to address specific automotive challenges. This paper will explain the fundamental TDDI and in-cell architecture including synchronization, electrode patterning and cascaded TDDIs systems. In addition, there will be explanations of the specific techniques developed for the automotive segment such as Zero Display Capacitance (ZDC), non-square wave sensing for EMC, and panel testing for yield control and defect detection over the vehicle's life-cycle. There will also be a proposed architecture for TDDI full in-cell system to support force sensing.