Ranging device and ranging methhod

1. A ranging device, comprising:

a light source configured to project a plurality of projection patterns onto a surface of an object to be measured at different times;

an image sensor configured to sense the surface in synchronization with projection times of the projection patterns of the object to be measured to obtain a plurality of sensing images respectively corresponding to the projection patterns; and

a processor coupled to the light source and the image sensor and configured to analyze the sensing images to determine depth information of the object to be measured, wherein the processor performs a trigonometric calculation to obtain the depth information,

wherein when a sequence of positions of the projection patterns in the sensing images does not conform to a projection sequence of the projection patterns, the processor determines the depth information by ignoring at least a part of the sensing images.

2. The ranging device according to claim 1 , wherein the processor determines that at least a part of the sensing images are a plurality of effective sensing images according to the projection sequence of the projection patterns and the positions of the projection patterns respectively in the sensing images, and calculate the depth information of the object to be measured according to the effective sensing images.

3. The ranging device according to claim 1 , wherein the projection patterns comprise a first projection pattern having a plurality of stripe patterns and a second projection pattern having a plurality of other stripe patterns, and the stripe patterns and the other stripe patterns are alternately arranged in an original reference pattern.

4. The ranging device according to claim 3 , wherein the processor calculates a part of the depth information of the object to be measured according to a first sensing image corresponding to the stripe patterns of the first projection pattern, and the processor calculates another part of the depth information of the object to be measured according to a second sensing image corresponding to the stripe patterns of the second projection pattern.

5. The ranging device according to claim 3 , wherein the processor overlays a first sensing image corresponding to the stripe patterns of the first projection pattern and a second sensing image corresponding to the stripe patterns of the second projection pattern to obtain an overlay image, and the processor analyzes positions of the projection patterns in the overlay image to determine the depth information of the object to be measured.

6. The ranging device according to claim 1 , wherein the image sensor comprises a complementary metal-oxide semiconductor image sensor.

7. The ranging device according to claim 1 , wherein the image sensor senses an image in a manner of global shutter.

8. The ranging device according to claim 1 , wherein the light source comprises an infrared light source.

9. A ranging method, comprising:

projecting a plurality of projection patterns onto a surface of an object to be measured at different times by a light source;

sensing the surface of the object to be measured by an image sensor in synchronization with projection times of the projection patterns to obtain a plurality of sensing images respectively corresponding to the projection patterns;

analyzing the sensing images to determine depth information of the object to be measured, wherein the depth information is generated by performing trigonometric calculations; and

when a sequence of positions of the projection patterns in the sensing images does not conform to a projection sequence of the projection patterns, determining the depth information by ignoring at least a part of the sensing images.

10. The ranging method according to claim 9 , wherein analyzing the sensing images to determine the depth information of the object to be measured comprises:

determining that at least a part of the sensing images are a plurality of effective sensing images according to the projection sequence of the projection patterns and the positions of the projection patterns respectively in the sensing images; and

calculating the depth information of the object to be measured according to the effective sensing images.

11. The ranging method according to claim 9 , wherein the projection patterns comprise a first projection pattern having a plurality of stripe patterns and a second projection pattern having a plurality of other stripe patterns, and the stripe patterns and the other stripe patterns are alternately arranged in an original reference pattern.

12. The ranging method according to claim 11 , wherein analyzing the sensing images to determine the depth information of the object to be measured comprises:

calculating a part of the depth information of the object to be measured according to a first sensing image corresponding to the stripe patterns of the first projection pattern; and

calculating another part of the depth information of the object to be measured according to a second sensing image corresponding to the stripe patterns of the second projection pattern.

13. The ranging method according to claim 11 , wherein analyzing the sensing images to determine the depth information of the object to be measured comprises:

overlaying a first sensing image corresponding to the stripe patterns of the first projection pattern and a second sensing image corresponding to the stripe patterns of the second projection pattern to obtain an overlay image; and

analyzing positions of the projection patterns in the overlay image to determine the depth information of the object to be measured.

14. The ranging method according to claim 9 , wherein the image sensor comprises a complementary metal-oxide semiconductor image sensor.

15. The ranging method according to claim 9 , wherein the image sensor senses an image in a manner of global shutter.

16. The ranging method according to claim 9 , wherein the light source comprises an infrared light source.