A PIXEL STRUCTURE

• US 20200137330A1
• Filed: 04/23/2018
• Published: 04/30/2020
• Est. Priority Date: 04/23/2017
• Status: Active Grant

• Current Assignee: Xenomatix NV
• Original Assignee: Xenomatix NV
• Inventors: VAN DYCK, Dirk, PAESEN, Rik
• Granted Patent: US 10,764,518 B2
• Time in Patent Office: Days
• CPC Class Codes: G01S 17/18 wherein range gates are used
• CPC Class Codes: G01S 17/894 3D imaging with simultaneous measurement of time-of-flight at a 2D array of receiver pixels, e.g. time-of-flight cameras or flash lidar
• CPC Class Codes: G01S 7/4863 Detector arrays, e.g. charge-transfer gates
• CPC Class Codes: H04N 25/59 by controlling the amount of charge storable in the pixel, e.g. modification of the charge conversion ratio of the floating node capacitance

Abstract

The present invention pertains to a pixel for use in a system for determining a distance to an object by range gating, said pixel comprising: a first charge storage well (221) and a second charge storage well (222) for accumulating electrical charges representative of amounts of light impinging on said pixel during respective sets of exposure intervals, wherein said first charge storage well (221) has a charge capacity that is at least 50% greater than a charge capacity of said second charge storage well (222). The invention also pertains to a range gating system comprising such a pixel.

Claims

1-5. -5. (canceled)

6. A system for determining a distance to an object by range gating, the system comprising:

a solid-state light source arranged for projecting a pattern of spots, preferably discrete spots, of light towards the object in a sequence of pulses, preferably a periodically repeated sequence of pulses;

a detector comprising an imaging array, the detector being configured for detecting light representing the pattern of spots as reflected by the object in synchronization with said sequence of pulses; and

processing means configured to calculate the distance to the object as a function of exposure values generated by said pixels in response to said detected light;

wherein said imaging array comprises a plurality of pixels, each of said pixels comprising;

a first charge storage well and a second charge storage well for accumulating electrical charges representative of amounts of light reflected by said object and impinging on said pixel during respective sets of exposure intervals, and a third charge storage well;

wherein said first charge storage well has a charge capacity that is at least 50% greater than a charge capacity of said second charge storage well; and

wherein said third charge storage well has a smaller charge storage capacity than said first charge storage well and said second charge storage well;

wherein the pixels of the imaging array are configured to generate said exposure values by accumulating, for all pulses of said sequence, a first amount of electrical charge representative of a first amount of light reflected by said object during a first predetermined time window and a second electrical charge representative of a second amount of light reflected by said object during a second predetermined time window, said second predetermined time window occurring after said first predetermined time window, whereby said solid-state light source is in its “

ON”

state during the first time window and in its “

OFF”

state during the second time window; and

wherein the detecting of the first amount of light and the detecting of said second amount of light occurs at said first charge storage well and at said second charge storage well, respectively.

7. The system according to claim 6, further configured to perform the projecting and the detecting for at least two consecutive sequences of pulses, each of the sequences being operated with a different duration of the first predetermined time window and the second predetermined time window.

8. The system according to claim 6, wherein the imaging array is further adapted to perform 2D video image acquisition.

9. The system according to claim 6, wherein said pixels further comprise circuitry a Rowing said pixel to switch between:

a charging mode, in which light impinging on said pixel causes said first charge storage well or said second charge storage well to increase a stored amount of charge, and

a discharging mode, in which light impinging on said pixel causes said first charge storage well or said second charge storage well to decrease a stored amount of charge.

10. The system according to claim 6, wherein said pixels further comprise circuitry allowing photocharges that are generated when an active one of said first charge storage well and said second charge storage well is filled to capacity, to be to deviated to a charge sink without entering a storage well of an adjacent pixel.

11. The system according to claim 6, wherein said pixels further comprise a fourth charge storage well.

12. The system according to claim 7, further configured to perform the projecting and the detecting for at least two consecutive sequences of pulses, each of the sequences being operated with a different duration of the first predetermined time window and the second predetermined time window.

13. The system according to claim 7, wherein the imaging array is further adapted to perform 2D video image acquisition.

14. The system according to claim 7, wherein said pixels further comprise circuitry a Rowing said pixel to switch between:

a charging mode, in which light impinging on said pixel causes said first charge storage well or said second charge storage well to increase a stored amount of charge, and

a discharging mode, in which light impinging on said pixel causes said first charge storage well or said second charge storage well to decrease a stored amount of charge.

15. The system according to claim 7, wherein said pixels further comprise circuitry allowing photocharges that are generated when an active one of said first charge storage well and said second charge storage well is filled to capacity, to be to deviated to a charge sink without entering a storage well of an adjacent pixel.

16. The system according to claim 7, wherein said pixels further comprise a fourth charge storage well.

17. The system according to claim 8, further configured to perform the projecting and the detecting for at least two consecutive sequences of pulses, each of the sequences being operated with a different duration of the first predetermined time window and the second predetermined time window.

18. The system according to claim 8, wherein the imaging array is further adapted to perform 2D video image acquisition.

19. The system according to claim 8, wherein said pixels further comprise circuitry allowing said pixel to switch between:

a charging mode, in which light impinging on said pixel causes said first charge storage well or said second charge storage, well to increase a stored amount of charge, and

a discharging mode, in which light impinging on said pixel causes said first charge storage well or said second charge storage well to decrease a stored amount of charge.

20. The system according to claim 8, wherein said pixels further comprise circuitry allowing photocharges that are generated when an active one of said first charge storage well and said second charge storage well is filled to capacity, to be to deviated to a charge sink without entering a storage well of an adjacent pixel.

21. The system according to claim 8, wherein said pixels further comprise a fourth charge storage well.