January 15, 2010


Posted in PDA, touch phone tagged , at 2:03 am by grace

In this article, we can see about one of the PDA’s technology, which has been frequently used in many Touch Phones. Infrared A schematic optical touch system uses an array of infrared LEDs [light emitting diode] It has been applied in two adjacent bezel edges of a display. Usually it has been applied with photo sensors placed on the two opposite bezel edges which is used to analyze the system and determines a touch event. Both the LED [light emitting diode] photo sensor pairs have been used to create a grid of light beams across the display. If an object [like human finger] touches the screen, then it will interrupt that light beams. In result it is causing a measured decrease in light at the corresponding photo sensors. The identified and measured photo sensor outputs can be used to locate a ‘touch point coordinate’ in “Touch phones” display. Wide spread adoption of infrared touch screens has been haltered by two factors. The relatively high cost of the technology when compared to competing with several touches technologies and the issue of performance in bright ambient light. This type of problem is a result of background light increasing the noise level at the optical sensor. But rarely such a degree that the touch screen’s light emitting diode cannot be detected at all will causing a temporary failure of the touch screen. This is most market in direct sunlight conditions where the sun has a very high energy distribution in the infrared region. Even so, certain features of infrared touch stays desirable and reflects attributes of the ideal touch screen including the option to decimate the glass or plastic over lay that most other touch technologies demand in front of the display. There is no doubt over this concept, which make “Touch phones” are better.


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