The patent's assignee for patent number 8508490 is
News editors obtained the following quote from the background information supplied by the inventors: "The present invention relates to a method of detecting a touch event for a touch panel and related device, and more particularly, to a method for enhancing efficiency of detecting a touch event and related device.
"Touch panels, which are usually combined with liquid crystal displays to form touch screens, are popular interfaces that allow people to control consumer electronics and equipment easily. Capacitive touch panels have higher sensitivity and are more durable than other types of touch panels, such as resistive touch panels, and have become a mainstream touch panel technology. Among capacitive touch panel technologies, projected capacitive touch panels have the most potential, because the projected capacitive touch panels can precisely detect the location of a touch event, and multi-touch functions can be implemented in the projected capacitive touch panels. A projected capacitive touch panel consists of intersecting Indium Tin Oxide (ITO) traces that act as row and column electrodes. A coupling node is formed at each intersection of a row trace and a column trace, and a capacitor is formed between the coupling node and a ground. When a user touches or approaches the coupling node, a body capacitance may be coupled to the capacitor at the coupling node. Therefore, a location of this touch event is determined by detecting which trace capacitance change occurs on.
"Please refer to FIG. 1, which is a schematic diagram of a touch control device 10 according to the prior art. The touch control device 10 is used for controlling a projected capacitive touch panel 12 consisting of intersecting ITO traces. The touch control device 10 comprises an analog-to-digital (A/D) converter 10 and a microprocessor 102. The A/D converter 100 is coupled to the touch panel 12 and the microprocessor 102, and is utilized for scanning all traces in the touch panel 12 for determining at which trace the capacitance change occurs. In detail, the A/D converter 100 sequentially outputs a charge control signal, e.g. a square wave signal, to each trace for charging/discharging a capacitor on each trace, and converts a voltage signal on each trace, which shows a charging/discharging curve, into a digital signal outputted to the microprocessor 102. When capacitance change happens on a trace, a voltage signal on the trace changes compared to a previous voltage signal taken on the same trace before the capacitance changed, so that a corresponding digital signal is also different from a previous digital signal taken before the capacitance changed. The microprocessor 102 is utilized for turning the A/D converter 100 on and off, for controlling the A/D converter 100 to scan the touch panel 12, and for adjusting operation modes of the touch panel 12 according to the digital signal generated by the A/D converter 100, so that the touch panel 12 can be operated within acceptable current consumption parameters. Briefly, the touch control device 10 determines that a touch event happens according to capacitance change on a trace, and controls operation modes of the touch panel 12.
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