红外触摸屏是通过红外发射管和红外接收管收发红外光来进行触摸位置的判断,其工作原理决定了太阳光会对它产生干扰.采用串行扫描方式的抗强光红外触摸屏的扫描周期很长.本文采用30.072 kHz、36 kHz、38 kHz、38.4 kHz、40 kHz、48 kHz、50 kHz、51.2 kHz无源晶振分别设计并行扫描模块中红外发射管的信号源和红外接收电路的选频器.模块实现了8个检测通道的同时工作.提高了红外触摸屏抗强光能力,解决了相邻8个红外发射管同时工作而产生的串扰问题,缩短了扫描周期.

Infrared touch screen works through light emitting diode transmitting infrared light and infrared receiver diode receiving infrared light,so the sunlight will have interference to it.Scanning period of anti-light infrared touch screens which use serial scanning mode is too long.Eight kinds of crystal ——30.072 kHz,36 kHz,38 kHz,38.4 kHz,40 kHz,48 kHz,50 kHz,51.2 kHz are used to design signal sources of infrared emission diodes.Then,the same frequency crystals are used to design frequency selective circuits.The design make eight scanning units working simultaneously come true.It enhances the anti-light ability of IR touch screen and solves the problem of interference among the eight infrared transmitting diode in parallel scanning mode,reducing scan cycle.