Device of acquisition of a 2D image and of a depth image of a scene
A device of acquisition of a depth image and of a 2D image of a scene, including depth photosites and capacitors, each depth photosite including a photodiode capable of detecting a reflected light signal, and at least one sense node coupled to the photodiode by a single transistor. Each capacitor is connected between the sense nodes of two photosites or between two sense nodes of a same photosite. Depth photosites supply the first plate of each capacitor with at least one first sample of charges photogenerated during first time periods, and supplying the second plate of each capacitor with a second sample of charges photogenerated during second time periods. Depth photosites supply the first plate of each capacitor with at least one third sample of charges photogenerated during third time periods.
1 . Device of acquisition of a depth image of a scene, comprising:
a) depth photosites, and capacitors, each comprising:
(i) a single photodiode, capable of detecting a reflected light signal corresponding to the reflection on the scene of an incident amplitude-modulated light signal in near infrared, and
(ii) at least one sense node coupled to the photodiode by a single transistor, and
b) Capacitors, each capacitor comprising first and second plates, each capacitor being connected between the sense nodes of two photosites or between two sense nodes of a same photosite,
wherein first depth photosites among the depth photosites are configured:
to supply the first plate of each first capacitor among the capacitors with at least one first sample of charges photogenerated by detection of the reflected light signal during first time periods each equal to a first portion of the modulation period of the incident light signal, and
to supply the second plate of each first capacitor with a second sample of charges photogenerated by detection of the reflected light signal during second time periods each equal to a second portion of the modulation period of the incident light signal, said second time periods being offset with respect to the first times periods by a first constant phase shift, and
wherein second depth photosites among the depth photosites are configured to supply the first plate of each second capacitor among the capacitors with at least one third sample of charges photogenerated by detection of the reflected light signal during third time periods each equal to a third portion of the modulation period of the incident light signal, said third time periods being offset with respect to the first times periods by a second constant phase shift different from the first phase shift.
2 . Device according to claim 1 , wherein the first and second samples are supplied by the same depth photosite.
3 . Device according to claim 1 , wherein the first and second samples are supplied by different depth photosites.
4 . Device according to claim 1 , wherein fourth depth photosites among the depth photosites are configured to supply the second plate of each third capacitor with a fourth sample of charges photogenerated by detection of the reflected light signal during fourth time periods each equal to a fourth portion of the modulation period of the incident light signal, said fourth time periods being offset with respect to the first time periods by a third constant phase shift different from the first and second phase shifts.
5 . Device according to claim 4 , wherein the third and fourth samples are supplied by the same depth photosite.
6 . Device according to claim 5 , wherein the first and second samples are supplied by a same photosite during the acquisition of a first depth image and wherein the third and fourth samples are supplied, during the acquisition of a second depth image, by the same depth photosite having supplied the first and second samples.
7 . Device according to claim 4 , wherein the first and second samples are supplied by a same depth photosite and wherein the third and fourth samples are supplied by a depth photosite different from the depth photosite having supplied the first and second samples.
8 . Device according to claim 4 , wherein the third and fourth samples are supplied by different depth photosites.
9 . Device according to claim 8 , wherein the first and second samples are supplied by different depth photosites and wherein the third and fourth samples are supplied by depth photosites different from the depth photosites having supplied the first and second samples.
10 . Device according to claim 8 , wherein the first and second samples are supplied by different depth photosites during the acquisition of a first depth image and wherein the third and fourth samples are supplied, during the acquisition of a second depth image, by the depth photosites having supplied the first and second samples.
11 . Device according to claim 1 , comprising 2D image pixels for the acquisition of a 2D image of the scene.
12 . System of acquisition of a depth image comprising the acquisition device according to claim 1 , a light source configured to emit the amplitude-modulated incident light signal in near infrared, and a processor configured to determine, from the first, second, and third samples, a phase shift between the incident light signal and the reflected light signal.
13 . System according to claim 12 , wherein the acquisition device comprises fourth depth photosites among the depth photosites are configured to supply the second plate of each third capacitor with a fourth sample of charges photogenerated by detection of the reflected light signal during fourth time periods each equal to a fourth portion of the modulation period of the incident light signal, said fourth time periods being offset with respect to the first time periods by a third constant phase shift different from the first and second phase shifts, and wherein the processor is configured to determine the phase shift between the incident light signal and the reflected light signal from the first, second, third, and fourth samples.