US 11,693,116 B2
Distance measurement device using two light modulation frequencies and operating method thereof
Yueh-Lin Chung, Hsin-Chu County (TW); and Tso-Sheng Tsai, Hsin-Chu County (TW)
Assigned to PIXART IMAGING INC., Hsin-Chu County (TW)
Filed by PixArt Imaging Inc., Hsin-Chu County (TW)
Filed on Aug. 31, 2020, as Appl. No. 17/7,491.
Prior Publication US 2022/0066035 A1, Mar. 3, 2022
Int. Cl. G01C 3/08 (2006.01); G01S 17/36 (2006.01); G01S 7/4915 (2020.01); G01S 7/4913 (2020.01); G01S 7/4911 (2020.01)
CPC G01S 17/36 (2013.01) [G01S 7/4911 (2013.01); G01S 7/4913 (2013.01); G01S 7/4915 (2013.01)] 19 Claims
OG exemplary drawing
 
1. A distance measurement device, configured to measure a distance of an object, the distance measurement device comprising:
a light source, configured to illuminate the object sequentially using a first modulation frequency and a second modulation frequency, higher than the first modulation frequency, according to a light driving signal;
a light detector, configured to detect reflected light from the object to generate a first detection signal corresponding to the light source being illuminating at the first modulation frequency and detect reflected light from the object to generate a second detection signal corresponding to the light source being illuminating at the second modulation frequency according to a detecting control signal;
a processor, configured to
calculate an operating phase zone of a first phase according to the first detection signal to accordingly determine a delay time,
cause the light driving signal and the detecting control signal to have a difference equal to the delay time when the light source is illuminating at the second modulation frequency, and
calculate a second phase according to the second detection signal to accordingly calculate an object distance.