红外传感技术

　　红外传感技术

　　接近传感器使用字段、光束或环境条件的变化，以便在可用范围内感知对象。使接近传感器在许多应用中有价值的一个关键特性是不需要物理接触。其结果是，电干扰、机械振动和其他形式的噪声可以在不降低检测信号的情况下存在，并危及传感器结果的可靠性。

　　可以使用几种技术，包括电场、rf、磁、电容、电感、声能量和光。本文研究了红外（IR）接近传感器解决方案，利用反射，环境条件的变化，和光束中断。这些传感器用于工业，消费和其他应用程序，用于检测运动，位置，接近，环境光，速度和方向。

　　Photo interruption

　　A photo interrupter is a photo sensor that integrates an optical receiver and emitter in a single package. Rotating machines will typically use a photo interrupter as a proximity detector. An emitter， typically infrared， sends a beam of light to a receiver that merely detects the presence of the IR light. Solid tachometer slotted wheels can be formed with as many teeth as needed to get the resolution desired at a specific rotational speed.

　　The timing wheel acts as a shaft encoder， allowing an embedded micro to determine the speed and acceleration of a rotating shaft. Using two of them 90° out of phase creates a quadrature encoder that also allows you to determine the direction of rotation. Photo-interrupted proximity sensors can also be used as a limit position sensor for linear actuators and rotational actuators. The addition of a home or reference sensor lets a timing wheel-based shaft encoder to become an incremental position sensor; by counting pulses you get a stepped position indicator.