Reflective sensors simplify optical switch designs

When you’re designing miniature optical switches, reflective sensors are your best friend.

They streamline the interaction between humans and machines in an elegant and intuitive manner. These sensors, typically concealed behind infrared (IR) transmissive covers, spring into action when a finger or another object touches the surface of the cover.

Optical sensors, or reflective sensors, simplify the process of designing a button that feels intuitively smart and operates reliably. The mechanism is as straightforward as it is efficient:

1. The sensor houses an emitter that throws out IR light on one side.

2. When a finger or any object draws near, it’s illuminated by this light.

3. The reflected signal creates a photocurrent at the detector situated on the other side.

These sensors work invisibly, with no moving parts or friction, and they have virtually no wear and tear. What’s more, optical sensors can be tweaked and fine-tuned to tackle moisture, water, dirt and scratches on the cover surface. They perform just as effectively with gloves on.

Do bear in mind that like any sensor integrated into an application, there are crucial challenges to consider to ensure everything functions as planned. For optical sensors, these are primarily environmental and mechanical hurdles within the application housing.

Environmental challenges

Imagine this: You’re dealing with ambient noise at the detector caused by external interference like sunlight and typical light sources. Now, let’s consider the offset current created by reflections from the surrounding aperture, dirt, water, moisture or scratches on the cover’s surface. This offset adds to the proximity signal, increasing the total amplitude of the output signal.