红外触摸屏通过发射接收红外光进行工作, 对环境光照因素的变化比较敏感。在有外界强光照的环境中使用红外触摸屏会受到极大干扰, 导致红外接收管接收到的光强发生异常, 从而引起误动作。本文研究了采用高频红外光的发射与接收, 以锁相放大方式滤除太阳光的干扰频段分量, 实现了红外触控屏的抗直接照射的阳光干扰的方法与验证结果。此外, 通过改进了锁相放大器的解调算法, 去掉传统的锁相放大后级所必须的滤波电路, 电路更加简洁、可靠。经硬件平台的实际验证, 选频Q值可以达到145985, 并能在50 000 lx的光强下正常工作。该算法能够实现很好的选频和抗强光效果, 达到抗干扰目的。

Infrared touch screen works through transmitting and receiving infrared light, which is sensitive in the change of environmental illumination factors.Infrared touch screen will be disturbed in the external strong light environment, leading that the infrared receiving tube receives light intensity abnormally and it may cause malfunction.First, high frequency infrared light transmission and reception is used to filter band component of sunlight interference by the method of lock-in amplifier. Second,the method of the direct exposure of sunlight anti-interference has been realized and its result is proved.In addition, the filter circuit which traditional amplification after stage haves is removed by improving the demodulation algorithm of the lock-in amplifier.This algorithm makes the circuit more simple and reliable.The hardware platform of the actual experiment indicates that frequency selection Q is 145.985,and it can work in the 50 000 lx light environment availably.It proves that the algorithm can achieve good frequency selection,and meet the requirement of anti-glare effect and anti-jamming.