A Low-Latency Multi-Touch Detector Based on Concurrent Processing of Redesigned Overlap Split and Connected Component Analysis

Abstract

A low-latency multi-touch detector architecture for locating numerous touches in large-panel devices is presented in this paper. Two respective processors for the overlap split and the connected component analysis (CCA) are the key components in a multi-touch detector. Exploiting the simplicity of typical intensity maps in practice, the two processors are first redesigned under a principle that every pixel is processed only once in a raster-scan order. More specifically, the concept of valley point is introduced, and a simple yet effective overlap-split scheme called valley-point division (VPD) is newly developed based on the concept. In addition, equivalent labels in the CCA are handled on the fly instead of being kept to be processed later, and the logics and memories for corner cases that never occur in practice are unloaded. Enabled by the redesign, subsequently, the two processors are integrated into one to concurrently conduct both the VPD and the CCA during the same raster scan. As a result, the proposed detector completes the whole detection procedure with a single raster scan of a map, and is exempted from a large memory required to hold an entire map. Implementation results in a 65-nm CMOS for a large panel of 400 x 250 sensors demonstrate that the proposed detector takes less than a half latency of the existing ones while occupying only 17% silicon area and consuming 52% power on average.