High dynamic range image sensor including polarizer and microlens

• US 7,964,840 B2
• Filed: 06/19/2008
• Issued: 06/21/2011
• Est. Priority Date: 06/19/2008
• Status: Active Grant

• Current Assignee: Omnivision Technologies Incorporated (Will Semiconductor Co., Ltd. Shanghai)
• Original Assignee: Omnivision Technologies Incorporated (Will Semiconductor Co., Ltd. Shanghai)
• Inventors: Parks, Christopher
• Primary Examiner(s): Epps; Georgia Y
• Assistant Examiner(s): Bennett; Jennifer
• Application Number:
  US12/141,993
• Publication Number:
  US 20090314928A1
• Time in Patent Office: 1,097 Days
• Field of Search: 250/208.1, 250/225, 250/216, 250/221, 257290-292, 257/257, 257/258, 257/294, 257431-437, 257/443, 257/451, 348/294, 348/302, 348/311, 348/315, 348/335
• US Class Current: 250/225
• CPC Class Codes: H01L 27/14627 Microlenses
• CPC Class Codes: H01L 27/14629 Reflectors

Abstract

An image sensor includes a plurality of pixels, each pixel includes a first photosensitive region that collects charge in response to light and having a first sensitivity; a second photosensitive region that collects charge in response to light and having a second sensitivity that is lower than the sensitivity of the first photosensitive region; and a polarizer spanning the second photosensitive region.

Claims

1. An image sensor comprising:

a plurality of pixels-with at least one pixel comprising;

a first photosensitive region that collects charge in response to light and having a first sensitivity and a second photosensitive region that collects charge in response to light and having a second sensitivity that is lower than the sensitivity of the first photosensitive region;

a polarizer spanning only the second photosensitive region and not the first photosensitive region; and

a first microlens covering the first photosensitive region and only partially covering the second photosensitive region.

2. The image sensor as claim 1 wherein the polarizer is a wire grid polarizer.

3. The image sensor as in claim 1 wherein the polarizer is oriented to block light that is polarized by surface reflections.

4. The image sensor as in claim 1 further comprising a third photosensitivity region that collects charge in response to light and having a sensitivity that is substantially equal or equal to the first sensitivity, and a fourth photosensitive region that collects charge in response to light and having a sensitivity equal or substantially equal to the second sensitivity.

5. The image sensor as in claim 4 further comprising a second polarizer spanning the fourth photosensitive region.

6. The image sensor as in claim 5 wherein the second polarizer is a wire grid polarizer.

7. The image sensor as in claim 6 wherein the second polarizer is oriented to block light that is polarized by surface reflections.

8. The image sensor as in claim 5 wherein the first and third photosensitive regions are positioned diagonal to each other and the second and fourth photosensitive regions are positioned diagonal to each other within the at least one pixel.

9. The image sensor as in claim 8 further comprising a second microlens covering the third photosensitive region and only partially covering the fourth photosensitive region.

10. An image capture device comprising:

an image sensor comprising;

a plurality of pixels with at least one pixel comprising;

a first photosensitive region that collects charge in response to light and having a first sensitivity and a second photosensitive region that collects charge in response to light and having a second sensitivity that is lower than the sensitivity of the first photosensitive region;

a polarizer spanning only the second photosensitive region and not the first photosensitive region; and

a first microlens covering the first photosensitive region and only partially covering the second photosensitive region.

11. The image capture device as claim 10 wherein the polarizer is a wire grid polarizer.

12. The image capture device as in claim 10 wherein the polarizer is oriented to block light that is polarized by surface reflections.

13. The image capture device as in claim 10 further comprising a third photosensitivity region that collects charge in response to light and having a sensitivity that is substantially equal or equal to the first sensitivity, and a fourth photosensitive region that collects charge in response to light and having a sensitivity equal or substantially equal to the second sensitivity.

14. The image capture device as in claim 13 further comprising a second polarizer spanning the fourth photosensitive region.

15. The image capture device as in claim 14 wherein the second polarizer is a wire grid polarizer.

16. The image capture device as in claim 15 wherein the second polarizer is oriented to block light that is polarized by surface reflections.

17. The image capture device as in claim 14 wherein the first and second photosensitive regions are positioned diagonal to each other and the second and fourth photosensitive regions are positioned diagonal to each other within the at least one pixel.

18. The image capture device as in claim 17 further comprising a second microlens covering the third photosensitive region and only partially covering the fourth photosensitive region.

19. An image sensor comprising:

a plurality of pixels with at least one pixel comprising;

a first photosensitive region and a second photosensitive region that collect charge in response to light, wherein the first photosensitive region and the second photosensitive region are positioned diagonal to each other within the at least one pixel;

a third photosensitive region and a fourth photosensitive region that collect charge in response to light, wherein the third photosensitive region and the fourth photosensitive region are positioned diagonal to each other within the at least one pixel;

a first polarizer spanning only the third photosensitive region;

a second polarizer spanning only the fourth photosensitive region, wherein polarizers do not span the first and second photosensitive regions;

a first microlens covering the first photosensitive region and only partially covering the third photosensitive region, wherein the first microlens produces a first sensitivity in the first photosensitive region and a second sensitivity that is less than the first sensitivity in the third photosensitive region; and

a second microlens covering the second photosensitive region and only partially covering the fourth photosensitive region, wherein the second microlens produces the first sensitivity in the second photosensitive region and the second sensitivity in the fourth photosensitive region.

20. The image sensor as in claim 19, wherein the microlens covering the first photosensitive region and only partially covering the third photosensitive region also only partially covers the third photosensitive region in an adjacent pixel.

21. The image sensor as in claim 19, wherein the microlens covering the second photosensitive region and only partially covering the fourth photosensitive region also only partially covers a fourth photosensitive region in an adjacent pixel.