By Steve Gerber, Director of Human Interface Products Silicon Laboratories
Imagine being able to control electronics products at home and in the office, not with a direct touch but with the sweep of your hand. Advanced “touchless” human interface technology is now within the realm of practical implementation, even for products as commonplace as the alarm clock beside your bed.
We all have experienced the frustration of locating the snooze and silence buttons on an incessantly beeping alarm clock at 6:00 a.m. What if you could extend your sleep just a bit longer by simply waving your hand or tapping a virtual button to shut off the alarm without fumbling to find the clock in the dark?
Touchless Slider The simple wave of a hand or tap of a virtual button is an intriguing product innovation not only for alarm clocks but also for an array of consumer and industrial applications, from cell phones and other hand-held devices to large appliances to factory control panels. One way to achieve this is a touchless slider, and the concept can be adapted to a great number of products that we encounter every day.
The touchless slider solution comprises two or more infrared LEDs, an infrared detector and a low-power 8-bit microcontroller (MCU) based on the 8051 core.
Figure 1 depicts a simplified single-axis infrared motion sensor. Two infrared LEDs are independ-ently pulsed, and an infrared sensor detects the reflected infrared light. A comparison of the strengths of the two reflections indicates the relative location of the object along the single axis.