US 11,937,000 B2
Methods and apparatus for ambient light suppression with subtractive image sensor
Jan Zizka, Ziar nad Hronom (SK); Tomas Kovacovsky, Bratislava (SK); and Michal Maly, Lutila (SK)
Assigned to Photoneo s.r.o., Bratislava (SK)
Filed by Photoneo s. r. o., Bratislava (SK)
Filed on Oct. 28, 2022, as Appl. No. 18/050,808.
Application 18/050,808 is a continuation of application No. 17/554,820, filed on Dec. 17, 2021, granted, now 11,516,415.
Application 17/554,820 is a continuation of application No. PCT/IB2020/055569, filed on Jun. 15, 2020.
Claims priority of provisional application 62/862,374, filed on Jun. 17, 2019.
Prior Publication US 2023/0073300 A1, Mar. 9, 2023
This patent is subject to a terminal disclaimer.
Int. Cl. H04N 25/60 (2023.01); H04N 25/46 (2023.01); H04N 25/50 (2023.01); H04N 25/77 (2023.01)
CPC H04N 25/60 (2023.01) [H04N 25/50 (2023.01); H04N 25/77 (2023.01)] 20 Claims
OG exemplary drawing
 
1. A method comprising, for each particular imaging pixel in a set of imaging pixels in a camera:
(a) generating electrical charge in a first photodiode of the particular pixel in response to light passes through a first optical filter and strikes the first photodiode;
(b) depleting from the first photodiode, at a rate of depletion, a first portion of the electric charge, in such a way that the rate of depletion depends on voltage in a region of a transistor, which voltage (i) controls amperage of an electrical current that flows from the first photodiode through the transistor during the depleting, and (ii) is controlled by electrical charge that is generated in a second photodiode of the particular pixel in response to light that passes through a second optical filter and strikes the second photodiode; and
(c) reading out a remaining portion of the electrical charge, which remaining portion remains after the first portion is depleted;
wherein
(1) light incident on the particular pixel comprises active light and ambient light,
(2) irradiance of ambient light that has passed through the first optical filter and is incident on the first photodiode differs by less than 25% from irradiance of ambient light that has passed through the second optical filter and is incident on the second photodiode,
(3) irradiance of active light that has passed through the second optical filter and is incident on the second photodiode is less than 25% of irradiance of active light that has passed through the first optical filter and is incident on the first photodiode, and
(4) the depleting reduces or eliminates an effect that the ambient light would otherwise have on a measurement taken by the particular pixel.