Synchronous imaging using segmented illumination

• US 20080245952A1
• Filed: 04/03/2007
• Published: 10/09/2008
• Est. Priority Date: 04/03/2007
• Status: Active Grant

• Current Assignee: Aptiv Technologies AG (Aptiv PLC)
• Original Assignee: Delphi Technologies, Inc. (BorgWarner Incorporated)
• Inventors: Taylor, Ronald M., Troxell, John R., Rege, Siddharth S.
• Granted Patent: US 7,745,771 B2
• Time in Patent Office: Days
• US Class Current: 250/208.1
• CPC Class Codes: G03B 15/05 Combinations of cameras with electronic flash apparatus; Electronic flash units
• CPC Class Codes: G03B 2215/0567 Solid-state light source, e.g. LED, laser
• CPC Class Codes: G03B 2215/0592 installed in front of light emitter
• CPC Class Codes: H04N 23/56 provided with illuminating means
• CPC Class Codes: H04N 23/74 by influencing the scene brightness using illuminating means
• CPC Class Codes: H04N 25/531 by controlling rolling shutters in CMOS SSIS

Abstract

In an actively illuminated imaging system, illumination of a segmented scene is synchronized with an image sensing period. A scene is segmented into a plurality of scene portions utilizing a segmented lens. In an aspect, a first scene portion is illuminated when an imager is actively collecting photogenerated charge from the first scene portion, and a second scene portion is illuminated when an imager is actively collecting photogenerated charge from the second scene portion. The sensitivity of an image sensor is maximized, while simultaneously minimizing the amount of light that must be supplied to illuminate a scene. An irradiance pattern is varied allowing a more uniform distribution of light. Bands of varying wavelength, polarization, and light intensity may be variously applied to illuminate individual scene segments, as needed to enhance an identification of an object in the scene. The present invention is particularly useful with high frame rate imaging systems.

Claims

1. A method of synchronizing an actively illuminated imaging system comprising:

segmenting a scene into a plurality of scene portions comprising a first scene portion and a second scene portion; and

sequentially illuminating the first scene portion and the second scene portion, wherein the first scene portion is illuminated when an imager is actively collecting photogenerated charge from the first scene portion, and the second scene portion is illuminated when the imager is actively collecting photogenerated charge from the second scene portion.

2. The method as in claim 1, wherein sequentially illuminating comprises employing a first light source to transmit to a first segment of a segmented lens to illuminate the first scene portion, and employing a second light source to transmit to a second segment of the segmented lens to illuminate the second scene portion.

3. The method as in claim 2, wherein the first light source transmits a first light, and the second light source transmits a second light, wherein the first light and the second light vary in at least one of band of wavelength and polarization.

4. The method as in claim 2, wherein the first light source transmits a first light intensity and the second light source transmits a second light intensity, to enhance an identification of an object in the scene.

5. The method as in claim 1, wherein segmenting the scene comprises dividing the plurality of scene portions one of vertically and horizontally.

6. The method as in claim 1, wherein segmenting the scene comprises segmenting the scene by imager pixel row.

7. The method as in claim 1, further comprising at least one of extending an integration time of the first scene portion pixel rows, reducing a readout time of the first scene portion pixel rows, and reducing a quantity of the first scene portion pixel rows, to allow for a time period during which the first scene portion pixel rows can be illuminated when the imager is actively collecting photogenerated charge from the first scene portion pixel rows.

8. The method as in claim 1, wherein the imaging system maintains a frame rate of at least about 30 frames per second.

9. The method as in claim 1, wherein the imaging system employs one of a global shutter imager and a rolling shutter imager.

10. The method as in claim 1, wherein imaging system is utilized in an automotive imaging application including monitoring driver gaze, vehicle night vision systems, vehicle backup aid systems, varying illumination of an object surrounding a vehicle, a security application, and augmenting illumination for a conventional imager.

11. An actively illuminated imaging system comprising:

a plurality of light sources for individually transmitting light; and

a segmented lens for receiving the individually transmitted light, and directing the individually transmitted light to a scene that is segmented into a plurality of scene portions comprising a first scene portion and a second scene portion, wherein the first scene portion and the second scene portion are sequentially illuminated, and wherein the first scene portion is illuminated when an imager is actively collecting photogenerated charge from the first scene portion, and the second scene portion is illuminated when the imager is actively collecting photogenerated charge from the second scene portion.

12. The system as in claim 11, wherein the plurality of light sources comprises a first light source and a second light source, wherein the first light source transmits to a first segment of the segmented lens to illuminate the first scene portion, and the second light source transmits to a second segment of the segmented lens to illuminate the second scene portion.

13. The system as in claim 12, wherein the first light source transmits a first light, and the second light source transmits a second light, wherein the first light and the second light vary in at least one of band of wavelength and polarization.

14. The system as in claim 12, wherein the first light source transmits a first light intensity and the second light source transmits a second light intensity, to enhance an identification of an object in the scene.

15. The system as in claim 11, wherein the plurality of scene portions are divided one of vertically and horizontally.

16. The system as in claim 11, wherein the scene is segmented by imager pixel row.

17. The system as in claim 11, wherein an integration time of the first scene portion pixel rows is extended, a readout time of the first scene portion pixel rows is reduced, and a quantity of the first scene portion pixel rows is reduced, to allow for a time period during which the first scene portion pixel rows can be illuminated when the imager is actively collecting photogenerated charge from the first scene portion pixel rows.

18. The system as in claim 11, wherein the imaging system maintains a frame rate of at least about 30 frames per second.

19. The system as in claim 11, wherein the imaging system employs one of a global shutter imager and a rolling shutter imager.

20. The system as in claim 11, wherein imaging system is utilized in an automotive imaging application including monitoring driver gaze, vehicle night vision systems, vehicle backup aid systems, varying illumination of an object surrounding a vehicle, a security application, and augmenting illumination for a conventional imager.