紅外傳感技術(shù)

　　接近傳感器使用字段、光束或環(huán)境條件的變化，以便在可用范圍內(nèi)感知對象。使接近傳感器在許多應(yīng)用中有價值的一個關(guān)鍵特性是不需要物理接觸。其結(jié)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(jié)果的可靠性。

　　可以使用幾種技術(shù)，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(huán)境條件的變化，和光束中斷。這些傳感器用于工業(yè)，消費和其他應(yīng)用程序，用于檢測運動，位置，接近，環(huán)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.