US 12,007,482 B2
Optical proximity sensor and corresponding method of operation
Delfo Nunziato Sanfilippo, Catania (IT)
Assigned to STMICROELECTRONICS S.r.l., Agrate Brianza (IT)
Filed by STMICROELECTRONICS S.r.l., Agrate Brianza (IT)
Filed on Sep. 3, 2020, as Appl. No. 17/011,867.
Claims priority of application No. 102019000015761 (IT), filed on Sep. 6, 2019.
Prior Publication US 2021/0072386 A1, Mar. 11, 2021
Int. Cl. G01S 17/36 (2006.01); G01J 1/42 (2006.01); G01S 7/481 (2006.01); G02B 1/11 (2015.01); G02B 3/00 (2006.01); G02B 5/20 (2006.01)
CPC G01S 17/36 (2013.01) [G01J 1/4204 (2013.01); G01S 7/4816 (2013.01); G02B 1/11 (2013.01); G02B 3/0056 (2013.01); G02B 5/20 (2013.01)] 18 Claims
OG exemplary drawing
 
1. An optical proximity sensor comprising:
a solid-state photo-electric converter;
a biasing circuit configured to bias the solid-state photo-electric converter; and
a control circuit, wherein the control circuit is configured to:
control the biasing circuit to apply, to the solid-state photo-electric converter, a bias signal modulated between a first value and a second value, the second value different from the first value, both the first value and the second value being higher than a breakdown voltage of the solid-state photo-electric converter, wherein a modulated optical signal is emitted by the solid-state photo-electric converter towards a target object in response to the bias signal being applied to the solid-state photo-electric converter,
receive an electrical output signal from the solid-state photo-electric converter, the electrical output signal being a function of a received modulated optical signal that is received at the solid-state photo-electric converter as a result of reflection of the modulated optical signal emitted towards the target object,
perform a phase comparison of the bias signal applied to the solid-state photo-electric converter against the electrical output signal received from the solid-state photo-electric converter,
produce a phase shift signal based on the phase comparison, the phase shift signal being a function of a phase shift between the modulated optical signal emitted towards the target object and the received modulated optical signal that is received at the solid-state photo-electric converter, and
compute a distance between the optical proximity sensor and the target object as a function of the phase shift signal.