Non-visible illumination scheme

• US 9,674,465 B2
• Filed: 06/03/2015
• Issued: 06/06/2017
• Est. Priority Date: 06/03/2015
• Status: Active Grant

• Current Assignee: Omnivision Technologies Incorporated (Will Semiconductor Co., Ltd. Shanghai)
• Original Assignee: Omnivision Technologies Incorporated (Will Semiconductor Co., Ltd. Shanghai)
• Inventors: Shan, Jizhang, Hsu, Ming-Kai
• Primary Examiner(s): AGGARWAL, YOGESH K
• Application Number:
  US14/729,585
• Publication Number:
  US 20160360124A1
• Time in Patent Office: 734 Days
• Field of Search: 3482231-2291, 348272-280
• CPC Class Codes: H01L 27/1464 Back illuminated imager structures
• CPC Class Codes: H01L 27/14645 Colour imagers
• CPC Class Codes: H04N 23/11 for generating image signals from visible and infrared light wavelengths
• CPC Class Codes: H04N 23/56 provided with illuminating means
• CPC Class Codes: H04N 23/72 Combination of two or more compensation controls
• CPC Class Codes: H04N 25/131 including elements passing infrared wavelengths
• CPC Class Codes: H04N 25/133 including elements passing panchromatic light, e.g. filters passing white light
• CPC Class Codes: H04N 25/135 based on four or more different wavelength filter elements
• CPC Class Codes: H04N 25/531 by controlling rolling shutters in CMOS SSIS
• CPC Class Codes: H04N 25/70 SSIS architectures; Circuits associated therewith
• CPC Class Codes: H04N 25/76 Addressed sensors, e.g. MOS or CMOS sensors

Abstract

Embodiments of an apparatus and process are described. The process includes capturing a first image frame using an image sensor, the image sensor including a pixel array comprising a plurality of pixels arranged in rows and columns and a color filter array optically coupled to the pixel array. A region of interest within the first image frame is determined, and the exposure time of the image sensor is adjusted to eliminate a substantial fraction of the visible light captured by the image sensor. A rolling shutter procedure is used with the pixel array to capture at least one subsequent frame using the adjusted exposure time, and a source of invisible radiation is activated while the rolling shutter enters the region of interest and deactivated when the rolling shutter exits the region of interest. Finally, an image of the region of interest is output. Other embodiments are disclosed and claimed.

Claims

1. An image sensor comprising:

a pixel array comprising a plurality of pixels arranged in rows and columns;

a color filter array optically coupled to the pixel array, the color filter array comprising a plurality of tiled minimal repeating units, each minimal repeating unit including;

a plurality of individual filters wherein the spectral photoresponses of the individual filters include at least three dual-band spectral photoresponses and one single-band spectral photoresponse; and

circuitry and logic coupled to the pixel array, wherein the logic comprises instructions that, when executed by the circuitry, cause the image sensor to;

capture a first image frame using an image sensor, the image sensor including a pixel array comprising a plurality of pixels arranged in rows and columns and a color filter array optically coupled to the pixel array;

determine a region of interest within the first image frame;

adjust the exposure time of the image sensor to eliminate a substantial fraction of the visible light captured by the image sensor;

use a rolling shutter procedure with the pixel array to capture at least one subsequent frame using the adjusted exposure time;

activate a source of invisible radiation while the rolling shutter enters the region of interest and deactivating the source of invisible radiation when the rolling shutter exits the region of interest wherein activating the source of invisible radiation while the rolling shutter scans through the region of interest comprises determining a delay based on the position of the region of interest within the image frame, determining a duration for the activation of the source of invisible radiation based on the dimensions of the region of interest, and determining an intensity of the source of invisible radiation based on the adjusted exposure time; and

output an image of the region of interest.

2. The image sensor of claim 1 wherein each dual-band spectral photoresponse includes a visible photoresponse and an non-visible photoresponse and wherein the single-band spectral photoresponse is the invisible spectral photoresponse.

3. The image sensor of claim 2 wherein the invisible photoresponse is infrared.

4. The image sensor of claim 2 wherein the visible photoresponses are selected from a set of primary colors including red, green, blue, magenta, cyan, and yellow.

5. The image sensor of claim 1 wherein the minimal repeating unit is:

6. The image sensor of claim 5 wherein D1 has red and infrared spectral photoresponses, D2 has green and infrared spectral photoresponses, D3 has blue and infrared spectral photoresponses, and S has an infrared spectral photoresponse.

7. The image sensor of claim 1, further comprising a radiation source coupled to the circuitry and logic, wherein the radiation source emits radiation at an invisible wavelength that corresponds to the spectral photoresponse of the single-band filter and wherein the logic includes instructions that, when executed by the circuitry, cause the circuitry to selectively activate and deactivate the radiation source.

8. The image sensor of claim 1 wherein the delay is the time between when the rolling shutter starts scanning the first row of the image frame and when the rolling shutter starts scanning the first row of the region of interest.

12. The process of claim 8 wherein the adjusted exposure time is determined by a process comprising:

capturing one or more discardable image frames taken at different exposure times; and

determining the adjusted exposure time based on the one or more discardable image frames.

13. The process of claim 12 wherein adjusting the exposure time comprises adjusting the length of a vertical blanking interval.

9. A process comprising:

capturing a first image frame using an image sensor, the image sensor including a pixel array comprising a plurality of pixels arranged in rows and columns and a color filter array optically coupled to the pixel array;

determining a region of interest within the first image frame;

adjusting the exposure time of the image sensor to eliminate a substantial fraction of the visible light captured by the image sensor;

using a rolling shutter procedure with the pixel array to capture at least one subsequent frame using the adjusted exposure time;

activating a source of invisible radiation while the rolling shutter enters the region of interest and deactivating the source of invisible radiation when the rolling shutter exits the region of interest, wherein activating the source of invisible radiation while the rolling shutter scans through the region of interest comprises determining a delay based on the position of the region of interest within the image frame, determining a duration for the activation of the source of invisible radiation based on the dimensions of the region of interest and determining an intensity of the source of invisible radiation based on the adjusted exposure time; and

outputting an image of the region of interest.

10. The process of claim 9 wherein activating the source of invisible radiation while the rolling shutter scans through the region of interest and deactivating the source of invisible radiation when the rolling shutter exits the region of interest comprises:

waiting for the delay to pass after a starting time of the image frame;

when the delay has expired, activating the source of invisible radiation at the determined intensity;

waiting for the duration to pass after activating the source of invisible radiation; and

when the duration has expired, deactivating the source of invisible radiation.

11. The process of claim 9 wherein the output image of the region of interest is a full-resolution image at the wavelength of the invisible radiation.

14. The process of claim 9 wherein the first image frame is a visible-light image.

15. The process of claim 9 wherein the delay is the time between when the rolling shutter starts scanning the first row of the image frame and when the rolling shutter starts scanning the first row of the region of interest.