Sharp Corp. announced on March 23, 2006 that it has developed "distance image CMOS sensor" that can determine the distance to an object as well as its shape. In order to provide these two functions, the company has adopted the Time-of-Flight (TOF) method as the distance measurement technique, in which a distance is back-calculated from the flight time of light. Commercialization is in progress, aiming at home appliances, automotive and security related products as its target applications.
The principle of distance measurement is as follows: First, near infrared light is emitted to an object at a fixed time interval by using LED provided in the vicinity of the CMOS sensor. Next, the reflected light is detected by the pixels of the sensor. Then, the flight time of near infrared light is obtained based on the phase difference between the emitted and reflected lights. Finally, the resultant flight time is multiplied by the speed of light to obtain the distance to the object. The sensor can also display images color-coded by the distance to objects. The sensor unit boasts the effective pixel count of 320 x 240 and the frame rate of 30 fps.
Atsushi Takano, Nikkei Monozukuri