US 12,222,453 B2
Optimized time of flight vision camera for a multi-camera environment
Pierre Fereyre, Voreppe (FR); Christophe Mailland, Grenoble (FR); and Pierre-Emmanuel Ville, Grenoble (FR)
Assigned to TELEDYNE E2V SEMICONDUCTORS SAS, Saint Egreve (FR)
Appl. No. 16/978,073
Filed by Teledyne e2v Semiconductors SAS, Saint Egreve (FR)
PCT Filed Mar. 1, 2019, PCT No. PCT/EP2019/055158
§ 371(c)(1), (2) Date Sep. 3, 2020,
PCT Pub. No. WO2019/170542, PCT Pub. Date Sep. 12, 2019.
Claims priority of application No. 1851944 (FR), filed on Mar. 7, 2018.
Prior Publication US 2020/0408917 A1, Dec. 31, 2020
Int. Cl. G01C 3/08 (2006.01); G01S 7/484 (2006.01); G01S 7/486 (2020.01); G01S 17/10 (2020.01); G01S 17/894 (2020.01)
CPC G01S 7/486 (2013.01) [G01S 7/484 (2013.01); G01S 17/10 (2013.01); G01S 17/894 (2020.01)] 9 Claims
OG exemplary drawing
 
1. A vision camera located within a camera housing and configured to measure time-of-flight at N capture phases, wherein N is an integer of at least 2, the vision camera comprising:
an electronic control circuit (C-MOD) configured to receive a carrier clock signal having a camera-defined carrier frequency (fp), and configured to produce a modulation clock signal (fe) at the carrier frequency;
a light emission source (S-LED), modulated by the modulation clock signal (fe), configured to emit a series of light pulses (SE) towards a target scene, wherein a duration (Tp) of a pulse and an interval between two successive pulses (Toff0) define a duty cycle of less than or equal to 50%; and
an image array sensor (CI) configured to receive the modulation clock signal and capture image samples corresponding to the N image capture phases (ST0, ST1, ST2, ST3) per integration period (TINT), wherein the N capture phases are synchronized with the light pulses emitted by the source, and wherein the integration period corresponds to a time period of the carrier clock signal,
wherein the electronic control circuit comprises a modulation circuit (MOD) configured to generate the modulation clock signal by applying a camera-specific pulse position modulation function (k (t)) to the carrier clock signal,
wherein the pulse position modulation function is a synthesized periodic signal having a frequency lower than the carrier frequency such that the pulses of the modulation clock signal (fe) have a constant pulse duration (Tp) equal to ½ (fp), and a variable time interval (Toff) between two successive pulses, and
wherein the variable time interval (Toff) is modulated by the modulation function (k(t)), such that the variable time interval (Toff) is at least equal to the pulse duration, thereby defining a variable modulation clock duty cycle which is less than or equal to 50%.