IR time-of-flight proximity sensor opens up new smartphone user interactions

February 26, 2013 // By Julien Happich
Combining three optical elements in a single compact package, the VL6180 is the first member of ST's FlightSense family and uses a new optical-sensing technology that enables innovative new user interactions with smartphones.

The VL6180 uses a proximity measuring technology to offer unprecedented accuracy and reliability in calculating the distance between the smartphone and the user. Instead of estimating distance by measuring the amount of light reflected back from the object, which is significantly influenced by colour and surface, the sensor precisely measures the time the light takes to travel to the nearest object and reflect back to the sensor. This “Time-of-Flight” approach ignores the amount of light reflected back and only considers the time for the light to make the return journey.

The key to ST’s patented new solution is an infra-red emitter that sends out light pulses, an ultra-fast light detector that picks up the reflected pulses, and electronic circuitry that accurately measures the time difference between the emission of a pulse and the detection of its reflection. Combining electronic, optical and packaging unique expertise from across the company, the VL6180 embeds both a robust ranging time-of-flight sensor and a wide dynamic ambient light sensor die, along with an infra-red emitter. Thanks to its all-in-one, ready- to-use architecture, the device is easy to integrate and saves the phone-makers long and costly optical and mechanical design optimizations. The ability to measure a reliable absolute distance from the phone to a hand or other object opens up new user interaction scenarios that phone manufacturers and app developers can rapidly exploit.

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