基于STM32的抗强光多点红外触摸屏的设计与实现

发布时间：2018-03-24 02:08

本文选题：多点触摸　切入点：抗强光干扰　出处：《电子科技大学》2013年硕士论文

【摘要】：单点触摸技术已经不能满足人们对工作、学习以及娱乐的要求，因此发展多点触摸技术变得势在必行。目前已经有多种触摸屏能够实现多点触摸功能，且根据各自的技术特点而被应用于不同的领域。红外触摸屏的发展已经有几十年历史了，由于红外屏没有漂移现象，不受电流、电压和静电干扰，透光率好等优点，已经越来越受到人们的青睐，但是其存在的一些缺陷却一直未被解决，例如抵抗环境光干扰的问题，因此也使红外屏的应用领域一直局限在环境光干扰较小的场合。本课题通过研究各种触摸屏的工作原理和适用领域，特别是研究了红外屏的工作原理和存在的一些缺陷，最终设计并开发了基于STM32芯片的抗强光多点红外触摸屏，并对设计方案进行了验证。本系统的硬件设计以STM32芯片为主控制器，通过控制逻辑芯片来实现红外触摸屏的矩阵扫描。信号采集部分通过电容与模拟开关构成的高通滤波器来提高红外屏抵抗环境光干扰的能力。选用高性能的运放芯片与数字电位器构成程控增益放大器，一方面提高了红外屏的使用寿命，另一方面也提高了红外屏抵抗环境光干扰的能力。整个系统采用USB通信和供电，设备即插即用，支持XP和WIN7系统，在WIN7系统下能直接实现多点触摸功能。系统在软件设计上更是采用了多种方法来提高红外屏的性能：采用一发两收的思想和移动平均滤波器的方法来提高红外屏的触摸精度。提出了冗余设计思想来提高红外屏的使用寿命。在实现真多点触摸过程中，首先分析了不同触摸点数时存在的伪点的情况，然后提出了采用斜扫描的方法来剔除伪点，最后从算法的角度阐述了怎样剔除伪点，实现真正的多点触摸。本课题设计的红外触摸能实现真两点触摸，具有很高的抗光干扰能力，能抵抗50,000勒克斯（Lx）以上的太阳光干扰，完全适用于户外环境。分辨率达到了4096*4096，而且触摸精度小于5mm，，同时还具有较快的响应时间，较长的使用寿命以及较低的成本，因此具有很高的工程意义和商业价值。
[Abstract]:Single-touch technology can no longer meet people's requirements for work, study and entertainment, so it is imperative to develop multi-touch technology. The infrared touch screen has been developed for several decades. Because the infrared screen has no drift phenomenon, it is not affected by current, voltage and electrostatic interference, and has good transmittance. Has become more and more popular, but some of its shortcomings have not been resolved, such as the problem of resisting environmental light interference. Therefore, the application field of infrared screen has been confined to the situation where the environmental light interference is small. This subject has studied the working principle and applicable field of various touch screens, especially the working principle and some defects of infrared screen. Finally, the multi-point infrared touch screen based on STM32 chip is designed and developed, and the design scheme is verified. The hardware of this system is designed with STM32 chip as the main controller. The matrix scan of infrared touch screen is realized by controlling logic chip. The signal acquisition part improves the ability of infrared screen to resist environmental light interference by high pass filter composed of capacitor and analog switch. Select high performance operational amplifier. The chip and the digital potentiometer constitute the programmable gain amplifier. On the one hand, it improves the service life of infrared screen, on the other hand, it also improves the ability of infrared screen to resist environmental light interference. The whole system adopts USB communication and power supply, equipment plug and play, support XP and WIN7 system, The function of multi-touch can be realized directly in WIN7 system. In software design, the system adopts many methods to improve the performance of infrared screen: the idea of "one send and two receiving" and the method of moving average filter are used to improve the touch accuracy of infrared screen. The idea of redundant design is put forward. Improve the service life of infrared screen. In the process of realizing true multi-touch, In this paper, the situation of pseudo points in different touch points is analyzed, then an oblique scanning method is proposed to eliminate pseudo points. Finally, from the point of view of algorithm, how to eliminate pseudo points and realize real multi point touch is expounded. The infrared touch designed in this paper can realize true two point touch, and has high ability of resisting light interference, and can resist the interference of sunlight above 50000 lux. It is fully suitable for outdoor environment. The resolution is 4096C 4096, and the touch precision is less than 5mm, and it also has fast response time, long service life and low cost, so it has high engineering significance and commercial value.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TP334.3;TN219

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