Distance measurement device based on phase difference

1. A distance measurement device, comprising:

a condensing lens having a predetermined focal length;

an image sensor configured to detect light passing through the condensing lens and output an image frame, the image sensor comprising:

a pixel matrix comprising a first pixel group and a second pixel group arranged in a first direction and a second direction;

a cover layer covering upon a first region of a plurality of first pixels of the first pixel group and upon a second region of a plurality of second pixels of the second pixel group, wherein the first region and the second region are mirror symmetric along the first direction, and respectively fully cover one of four edges of the first pixels and the second pixels in the first direction; and

a plurality of microlenses, each of the microlenses aligned with at least one of one of the first pixels and one of the second pixels; and

a processor configured to calculate a depth of an image region in the image frame.

2. The distance measurement device as claimed in claim 1 , wherein the processor is configured to

divide the image frame into a first subframe and a second subframe,

calculate an offset corresponding to the image region according to the first subframe and the second subframe, and

calculate the depth according to the offset,

wherein the first subframe is associated with the first pixel group and the second subframe is associated with the second pixel group.

3. The distance measurement device as claimed in claim 2 , wherein the processor further comprises a storage unit configured to previously store a relationship of a plurality of offsets and a plurality of depth differences from the predetermined focal length.

4. The distance measurement device as claimed in claim 2 , wherein the processor is further configured to calibrate brightness of the first subframe and the second subframe to be identical using a shading algorithm.

5. The distance measurement device as claimed in claim 1 , wherein the first region and the second region are 5% to 95% of an area of a single pixel.

6. The distance measurement device as claimed in claim 1 , wherein

the pixel matrix further comprises a third pixel group and a fourth pixel group,

the cover layer further covers upon a third region of a plurality of third pixels of the third pixel group and upon a fourth region of a plurality of fourth pixels of the fourth pixel group, and

the third region and the fourth region are mirror symmetric along the second direction, and respectively fully cover one of four edges of the third pixels and the fourth pixels in the second direction.

7. The distance measurement device as claimed in claim 6 , wherein

one of the first pixels, one of the second pixels, one of the third pixels and one of the fourth pixels adjacent to each other form a sub pixel group, and

the first region, the second region, the third region and the fourth region in the sub pixel group have identical areas.

8. The distance measurement device as claimed in claim 7 , wherein in two sub pixel groups adjacent in the first direction and the second direction,

the first region to the fourth region in a first sub pixel group are 50% of an area of a single pixel, and

the first region to the fourth region in a second sub pixel group are 5% to 45% or 55% to 95% of an area of a single pixel.

9. The distance measurement device as claimed in claim 6 , wherein

the first pixels are adjacent to the second pixels along a diagonal direction of the pixel matrix, and

the third pixels are adjacent to the fourth pixels along another diagonal direction of the pixel matrix.

10. The distance measurement device as claimed in claim 1 , wherein the cover layer is formed by electrical paths in the pixel matrix.

11. A distance measurement device, comprising:

a condensing lens having a predetermined focal length;

a pixel matrix comprising a first pixel group, a second pixel group, a third pixel group and a fourth pixel group arranged along a first direction and a second direction, and configured to detect light passing through the condensing lens to output an image frame; and

a cover layer covering upon the pixel matrix, the cover layer comprising:

a first cover pattern covering upon a first region of a plurality of first pixels of the first pixel group;

a second cover pattern covering upon a second region of a plurality of second pixels of the second pixel group;

a third cover pattern covering upon a third region of a plurality of third pixels of the third pixel group; and

a fourth cover pattern covering upon a fourth region of a plurality of fourth pixels of the fourth pixel group;

wherein the first region and the second region are mirror symmetric along the first direction, the third region and the fourth region are mirror symmetric along the second direction, the first region and the second region respectively fully cover one of four edges of the first pixels and the second pixels in the first direction, and the third region and the fourth region respectively fully cover one of four edges of the third pixels and the fourth pixels in the second direction.

12. The distance measurement device as claimed in claim 11 , wherein

one of the first pixels, one of the second pixels, one of the third pixels and one of the fourth pixels adjacent to each other form a sub pixel group, and

in two sub pixel groups adjacent along the first direction and the second direction, the first region to the fourth region of a first sub pixel group are 50% of an area of a single pixel, and the first region to the fourth region of a second sub pixel group are 5% to 95% of an area of a single pixel.

13. The distance measurement device as claimed in claim 11 , wherein

the first pixels are adjacent to the second pixels along a diagonal direction of the pixel matrix, and

the third pixels are adjacent to the fourth pixels along another diagonal direction of the pixel matrix.

14. The distance measurement device as claimed in claim 11 , wherein the cover layer is formed by electrical paths in the pixel matrix.

15. The distance measurement device as claimed in claim 11 , further comprising a processor configured to

divide the image frame into a first subframe and a second subframe, wherein the first subframe is associated with the first pixel group and the second subframe is associated with the second pixel group,

divide the image frame into a third subframe and a fourth subframe, wherein the third subframe is associated with the third pixel group and the fourth subframe is associated with the fourth pixel group,

calculate a first offset of a corresponded image region in the first subframe and the second subframe, and calculate a second offset of the corresponded image region in the third subframe and the fourth subframe, and

calculate a first depth of the image region according to the first offset, and calculate a second depth of the image region according to the second offset.

16. The distance measurement device as claimed in claim 11 , wherein

each pixel of the pixel matrix has four different edges, and

the first cover pattern, the second cover pattern, the third cover pattern and the fourth cover pattern fully cover a different edge among the four edges of the covered pixel, respectively.