紅外傳感技術

　　接近傳感器使用字段、光束或環境條件的變化，以便在可用范圍內感知對象。使接近傳感器在許多應用中有價值的一個關鍵特性是不需要物理接觸。其結果是，電干擾、機械振動和其他形式的噪聲可以在不降低檢測信號的情況下存在，并危及傳感器結果的可靠性。

　　可以使用幾種技術，包括電場、rf、磁、電容、電感、聲能量和光。本文研究了紅外（IR）接近傳感器解決方案，利用反射，環境條件的變化，和光束中斷。這些傳感器用于工業，消費和其他應用程序，用于檢測運動，位置，接近，環境光，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.