使用接近檢測和環(huán)境光傳感，以節(jié)省物聯(lián)網(wǎng)設備功率

　　許多便攜式電子設備結合環(huán)境光傳感器（ALS）和接近檢測器，既提高了用戶體驗，最大限度地降低功耗。直到最近，這些組合傳感器已被限制在范圍為幾毫米的接近傳感器，從而限制其應用到智能手機。

　　然而，許多物聯(lián)網(wǎng)應用，包括恒溫器，家用電器，辦公設備，照明控制，以及其他也可以受益于電路板空間和節(jié)省功率的集成設備具有較長的檢測范圍。這是在Vishay Intertechnology新近出臺的vcnl4100ct設計的動力。

　　本文將探討ALS和接近傳感，因為它涉及到移動和物聯(lián)網(wǎng)設備的應用。然后介紹vcnl4100ct，描述它是如何運作的，以及如何得到它的最為你的下一個設計。

　　ALS and proximity sensors save power

　　In displays for portable devices， the ALS is used to determine the screen display intensity needed under varying light conditions. This aids screen readability and the overall user experience， while conditionally reducing power consumed by the display. Some devices， such as smartphones， also use an optical proximity detector. The sensor output can be used to disable the touchscreen function and turn off the display. This reduces the odds that a user’s ear or cheek could hang up the call， mute the speaker， or engage some other unwanted function.

　　Turning off the display while close to your face also extends battery life. If a user brings the device away from their ear to perform another task such as picking up another call， the proximity sensor will detect that action and the screen and the touch function can be re-enabled， ready for input.

　　Combining proximity and ambient light sensors into a single package has been common practice in the handheld market for several years. The integration takes advantage of the fact that photo detectors are used for both functions. For ambient light detection， the photo diode output is processed and filtered to mimic the response of the human eye. This information is then used to appropriately dim the screen. For proximity detection， an infrared emitting diode （IRED） sends out pulsed energy and a photo detector tuned to the IRED wavelength looks for that reflected energy. The combination saves valuable board space by using a single package that shares power and communication with the outside world.