Imager with active exposure correction

• US 10,154,200 B2
• Filed: 05/19/2017
• Issued: 12/11/2018
• Est. Priority Date: 05/20/2016
• Status: Active Grant

• Current Assignee: Gentex Corporation
• Original Assignee: Gentex Corporation
• Inventors: Rycenga, Brock R., Hilldore, Benjamin B., Nelson, Barry K.
• Primary Examiner(s): Tran, Nhan T
• Application Number:
  US15/599,499
• Publication Number:
  US 20170339326A1
• Time in Patent Office: 571 Days
• Field of Search: 3482291
• CPC Class Codes: B60R 11/04 Mounting of cameras operative during drive; Arrangement of controls thereof relative to the vehicle
• CPC Class Codes: G02F 1/157 Structural association of cells with optical devices, e.g. reflectors or illuminating devices
• CPC Class Codes: G02F 1/163 Operation of electrochromic cells, e.g. electrodeposition cells; Circuit arrangements therefor
• CPC Class Codes: G03B 11/00 Filters or other obturators specially adapted for photographic purposes
• CPC Class Codes: G03B 7/097 for control of both exposure time and aperture
• CPC Class Codes: G03B 9/02 Diaphragms
• CPC Class Codes: H04N 23/51 Housings
• CPC Class Codes: H04N 23/71 Circuitry for evaluating the brightness variation
• CPC Class Codes: H04N 23/73 by influencing the exposure time
• CPC Class Codes: H04N 23/745 Detection of flicker frequency or suppression of flicker wherein the flicker is caused by illumination, e.g. due to fluorescent tube illumination or pulsed LED illumination
• CPC Class Codes: H04N 23/75 by influencing optical camera components

Abstract

An imager module for a vehicle is disclosed. The imager module comprises an imager configured to capture image data over a plurality of image frames based on incoming light in a field of view and an optic device configured to control a transmission of the incoming light. The module comprises a controller configured to identify an exposure time for the imager based on environmental lighting conditions and adjust the exposure time by a flicker mitigation period. The adjustment of the exposure time mitigates an appearance of a periodic light source in the image data. The controller is further configured to control the transmission of the optic device to control the transmission of the incoming light.

Claims

1. An imager module for a vehicle comprising:

an imager configured to capture image data over a plurality of image frames based on incoming light in a field of view;

an electro-optic device configured to vary in transmittance controlling a transmission of the incoming light into the imager; and

a controller in communication with the imager and the electro-optic device, wherein the controller is configured to;

identify an exposure time for the imager based on environmental lighting conditions in the field of view;

control the exposure time based on the environmental lighting conditions;

identify a light source having a periodic activation;

adjust the exposure time to an adjusted exposure based on a periodicity of the periodic activation; and

control the transmittance of the electro-optic device controlling the average transmission of the incoming light, wherein the average transmission of the electro-optic device is maintained over a plurality of cycles of the periodic activation.

2. The module according to claim 1, wherein the electro-optic device comprises an electrochromic device configured to change in transmittance in response to an electrical potential applied by the controller.

3. The module according to claim 1, wherein the light source having the periodic activation is identified by identifying an object with a varying luminance over the plurality of image frames.

4. The module according to claim 3, wherein the object corresponds to a light source configured to illuminate periodically with a frequency greater than 30 Hz.

5. The module according to claim 1, wherein the controller is further configured to:

adjust the exposure time to the adjusted exposure based on the average transmission of the incoming light.

6. The module according to claim 5, wherein the adjusted exposure is temporally increased in response to the average transmission of the incoming light decreasing due to a decreased transmittance of the optic device.

7. The module according to claim 6, wherein the exposure time is temporally increased capturing the plurality of cycles and mitigating a lighting intensity fluctuation in the adjusted exposure relative to the exposure time.

8. An imager module for a vehicle comprising:

an imager configured to capture image data over a plurality of image frames based on incoming light in a field of view;

an optic device configured to control an average transmission of the incoming light into the imager over the plurality of image frames; and

a controller in communication with the imager and the optic device, wherein the controller is configured to;

identify an exposure time for the imager based on environmental lighting conditions in the field of view;

adjust the exposure time mitigating an appearance of a periodic light source in the image data; and

control a transmittance of the optic device controlling the average transmission of the incoming light, wherein the transmission of the optic device is maintained limiting the average luminance of the light entering the imager from exceeding a saturation threshold over the plurality of image frames.

9. The imager module according to claim 8, wherein the adjustment of the exposure time comprises extending the exposure time by a flicker mitigation period.

10. The imager module according to claim 9, wherein the controller controls the average transmission of the incoming light with the optic device commensurate to a ratio of the flicker mitigation period to the exposure time for the imager based on environmental lighting conditions.

11. The imager module according to claim 8, wherein the controller is configured to mitigate a variation in the appearance of the periodic light source in the image data by increasing the exposure time of a pixel of the imager.

12. The imager module according to claim 11, wherein the controller is configured to increase the exposure time of the pixel of the imager capturing an increased portion of a plurality of active periods of the periodic light source relative to the exposure identified based on the environmental lighting conditions.

13. The imager module according to claim 8, wherein the optic device corresponds to an electro-optic device configured to vary in transmittance in response to a control signal from the controller.

14. The imager module according to claim 13, wherein the electro-optic device comprises an electrochromic medium configured to adjust the transmittance in response to the control signal.

15. A method for capturing image data for a vehicle imaging system, the method comprising:

capturing image data in a field of view of an imager;

identifying an exposure time for the imager based on an environmental lighting condition in the field of view;

controlling an exposure time based on the environmental lighting conditions;

controlling a transmission of an electro-optic device controlling a transmission of the environmental light transmitted through the electro-optic device; and

extending the exposure time by controlling the average transmission of the light entering the imager, wherein the transmission of the optic device is maintained over a plurality of continuous image frames limiting the average luminance of a plurality of pixels of the imager from exceeding a saturation threshold.

16. The method according to claim 15, further comprising:

identifying a flickering light source in the image data.

17. The method according to claim 16, further comprising:

identifying a minimum exposure time based on a frequency of the flickering light source.

18. The method according to claim 17, wherein the exposure time is extended to an extended exposure time based on the minimum exposure time.

19. The method according to claim 17, wherein the frequency of the flickering light source is identified based on a variation in a luminance value of an object in the image data over the plurality of image frames.