| Summary: | 碩士 === 國立彰化師範大學 === 電子工程學系 === 99 === To develop the multi-touch recognition related signal processing modules based on a traditional resistive touch screen is the main theme of this paper. The multi-touch recognition module on a resistive touch screen refers sequentially timed events to determine the behavior of fingers that plays the role of multi-touch input device for human-computer interface. The multi-touch recognition module consists of a Low-Pass Filter, Difference circuit, De-bouncing circuit, Discrimination unit, Octant unit, and Encoder circuit. Its functions include multi-finger touch detection, finger’s touching location, moving speed and direction on the resistive touch screen. The recognition results are similar to the mouse multi-byte encoding output that provide the GUI control actions on the operating system or application program for human-computer interface. When the fingers touching, it produces the current coordinate signals which are processed by the Low-Pass Filter. To input the Difference circuit to generate the differential signals, and the threshold value comparing generates the events code of normal-mobile, fast-moving, touching, and finger leaving. The event code is input to Octant unit and De-bouncing circuit. Octant unit is used to identify the direction of finger movement. And De-bouncing circuit is designed to eliminate the bouncing noise from touching. Thereby producing the signal of finger touching and leaving (Event) is input to the Discrimination Unit. It includes a set of state machine is used to determine the number of fingers and output the number. Finally, the Encoder will collect the code of direction, fingers, and the current coordinates. Those are re-encoded into a code as the output of the identification system. Multi-touch identification module is verified by NIOS II verification support system for the functional verification of digital circuits. And using Visual Basic is for verification of Applications graphical interactive human-computer interface, the results can reach the multi-touch functionality of requirements.
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