System and method for determining a distance to an object

1. A system for determining a distance to an object comprising:

a semiconductor light source arranged for projecting a pattern of discrete spots of laser light towards said object in a periodically repeated sequence of pulses;

a detector comprising a plurality of CMOS picture elements, said detector being configured for detecting light representing said pattern of discrete spots as reflected by said object in synchronization with said sequence of pulses, said detector being provided with a narrowband filter; and

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

wherein said picture elements are configured to generate said exposure values by accumulating, for all of the 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;

wherein each of said plurality of picture elements comprises at least two charge storage wells, and wherein said detecting of said first amount of light and said detecting of said second amount of light occurs at respective ones of said at least two charge storage wells;

wherein said first charge storage well used for said detecting of said first amount of light has a charge storage capacity that is greater than said second charge storage well used for said detecting of said second amount of light; and

wherein each of said plurality of picture elements comprises at least one further charge storage well configured to perform the function of acquiring background light values, said at least one further charge storage well having a charge storage capacity that is smaller than a charge storage capacity of said at least two charge storage wells.

2. The system according to claim 1 , 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.

3. The system according to claim 1 , wherein said first predetermined time window and said second predetermined time window are of substantially equal duration and occur back-to-back.

4. The system according to claim 1 , further configured to interleave said first and second predetermined time windows with time windows during which said plurality of picture elements are used in said acquiring of background light values.

5. A vehicle comprising a system according to claim 1 , wherein said system is arranged to operatively cover at least a part of an area surrounding said vehicle.

6. A camera, the camera comprising a system according to claim 1 , wherein the system is adapted to add 3D information to the camera image based on information obtained from the system, making it possible to create a 3D image.

7. A method for determining a distance to an object, the method comprising:

using a semiconductor light source to project a pattern of discrete spots of laser light towards said object in a periodically repeated sequence of pulses;

using a detector comprising a plurality of CMOS picture elements to detect light representing said pattern of discrete spots as reflected by said object in synchronization with said sequence of pulses, said detector being provided with a narrowband filter; and

calculating said distance to said object as a function of exposure values generated by said picture elements in response to said detected light;

wherein said picture elements generate said exposure values by accumulating, for all of the 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 amount of 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;

wherein each of said plurality of picture elements comprises at least two charge storage wells, and wherein said detecting of said first amount of light and said detecting of said second amount of light occurs at respective ones of said at least two charge storage wells;

wherein said first charge storage well used for said detecting of said first amount of light has a charge storage capacity that is greater than said second charge storage well used for said detecting of said second amount of light;

and wherein each of said plurality of picture elements comprises at least one further charge storage well configured to perform the function of acquiring background light values, said at least one further charge storage well having a charge storage capacity that is smaller than a charge storage capacity of said at least two charge storage wells.

8. The method according to claim 7 , wherein said first predetermined time window and said second predetermined time window are of substantially equal duration and occur back-to-back.

9. The method according to claim 7 , wherein said projecting, said detecting, and said calculating are repeated periodically.

10. The method according to claim 7 , wherein said first and second predetermined time windows are interleaved with time frames during which said plurality of picture elements are used in said acquiring background of light values.

11. A non-transitory computer program product comprising code means configured to cause a processor to carry out the method according to claim 7 .