Optical Switch

With minimal component outlay (two LEDs, one photodiode, one HALIOS^®-IC) it is possible to realize a switch or pushbutton free of mechanics characterized by two crucial benefits: insensitivity to ambient light conditions and freedom of design to the greatest possible extend.

In addition the device is able to detect an approaching hand. This feature can be used to either reactivate a system in power safe mode or to integrate a background light illuminating the device before an actual touch activates the system.

The system is deactivated as soon as a finger or hand is removed from the sensitive surface. Thus an accidentally wipe over the user surface does not lead to an activation.

An additional advantage of such a switch: the distance between IR-transparent surface (housing) and the optical sensor can to a certain extent be chosen freely. Thus it is for example possible to place several switches on
a plane PCB behind a domed housing.

The position of the sensitive area can be indicated by a special imprint on the surface. The diameter of the active sensor area in the user interface measures approximately 10 mm.

In combination with a µC the switch algorithms can be predetermined making it possible to implement gestically operated switches.

Example 1: Optical Switch with Wipe-off function
Switch process activated via tap on the surface
Switch off via wipe over active surface

Example 2: Pick & Place
In future it is possible to realize control systems operated intuitively via a pick & place function. One possible application area for these could be the control of a cooker: The user takes (pick function) the desired function from a cooking or temperature scale and assigns it to the corresponding cooking field symbol by simply tapping (place function) on it.

Learn more about the MECHALESS Evaluation Board "Optical Switch" (IC 909.01)