Liquid level detecting method and device using the same

1. A liquid level detecting method, comprising:

capturing a transmissive container image of a transmissive container and a marking component image of a marking component from a front surface of a transmissive container by a camera, wherein the transmissive container is configured for containing a liquid, and the marking component is located on a rear surface of the transmissive container;

analyzing the marking component image downward from an end portion of the marking component image to obtain a plurality of width values of a plurality of position points of the marker component image;

obtaining a width difference between each width value and a width average of the marking component image; and

determining the position point whose width difference is not within a preset range as a liquid level of the liquid.

2. The liquid level detecting method according to claim 1 , further comprising:

setting each of pixels of the transmissive container image and the marking component image to a first gray level; and

setting each of pixels other than the pixels of the transmissive container image and the marking component image to a second gray level different from the first gray level;

wherein the step of obtaining the width values of the position points of the marking component image comprises:

at each position point, calculating a cumulative count of the pixels of the marking component image that have the first gray level and determining the width value according to the cumulative count of pixels.

3. The liquid level detecting method according to claim 2 , wherein the first gray level is 0, and the second gray level is 255.

4. The liquid level detecting method according to claim 1 , wherein a first mark and a second mark are located on a front surface of the transmissive container; the step of capturing the transmissive container image from the front surface by the camera further comprises capturing a first mark image of the first mark and a second mark image of the second mark; the step of analyzing the marking component image downward from an end portion of the marking component image further comprises:

at each position point, calculating the width value of each position point from a starting point, being a connection line connecting the first mark image and the second mark image, towards a direction substantially perpendicular to the connection line.

5. The liquid level detecting method according to claim 4 , wherein the step of calculating the width value of each position point further comprises:

at each position point, calculating the width value within the range of a distance towards a direction substantially perpendicular to the connection line.

6. The liquid level detecting method according to claim 1 , the first mark and the second mark are located on a front surface of the transmissive container; the extending direction of the marking component is substantially parallel to the direction of a connection line connecting the first mark and the second mark.

7. The liquid level detecting method according to claim 6 , wherein the first mark is a first triangle; the second mark is a second triangle; the bottom side of the first mark and the bottom side of the second mark are opposite to each other.

8. The liquid level detecting method according to claim 6 , wherein the connection line connecting the first mark and the second mark passes through the marking component.

9. The liquid level detecting method according to claim 6 , wherein the first mark, the second mark and the marking component are separated from one another.

10. The liquid level detecting method according to claim 1 , wherein the preset range is between 0.1˜1.5.

11. A liquid level detecting device for detecting a liquid level of a liquid contained in a transmissive container, wherein a marking component is located on a rear surface of the transmissive container, and the liquid level detecting device comprises:

a camera for capturing a transmissive container image of a transmissive container and a marking component image of a marking component from a front surface of a transmissive container;

an image analyzer for:

analyzing the marking component image downward from an end portion of the marking component image to obtain a plurality of width values of a plurality of position points of the marker component image; and

obtaining a width difference between each width value and a width average of the marking component image; and

a liquid level determiner configured for:

determining the position point whose width difference is not within a preset range as the liquid level of the liquid.

12. The liquid level detecting device according to claim 11 , wherein the image analyzer further is configured for:

setting each of the pixels of the transmissive container image and the marking component image to a first gray level; and

setting each of the pixels other than the pixels of the transmissive container image and the marking component image to a second gray level different from the first gray level;

wherein the step of obtaining the width values of the position points of the marking component image comprises:

at each position point, calculating a cumulative count of the pixels of the marking component image that have the first gray level and determining the width value according to the cumulative count of pixels.

13. The liquid level detecting device according to claim 12 , wherein the first gray level is 0, and the second gray level is 255.

14. The liquid level detecting device according to claim 11 , wherein a first mark and a second mark are located on a front surface of the transmissive container; the camera further is configured for capturing a first mark image of the first mark and a second mark image of the second mark from the front surface of the transmissive container; the image analyzer further is configured for:

at each position point, calculating the width value of each position point from a starting point, being a connection line connecting the first mark image and the second mark image, towards a direction substantially perpendicular to the connection line.

15. The liquid level detecting device according to claim 14 , wherein the image analyzer further is configured for:

at each position point, calculating the width value within the range of a distance towards a direction substantially perpendicular to the connection line.

16. The liquid level detecting device according to claim 11 , wherein a first mark and a second mark are located on a front surface of the transmissive container; the extending direction of the marking component is substantially parallel to the direction of a connection line connecting the first mark and the second mark.

17. The liquid level detecting device according to claim 16 , wherein the first mark is a first triangle; the second mark is a second triangle; the bottom side of the first mark and the bottom side of the second mark are opposite to each other.

18. The liquid level detecting device according to claim 16 , wherein the connection line connecting the first mark and the second mark passes through the marking component.

19. The liquid level detecting device according to claim 16 , wherein the first mark, the second mark and the marking component are separated from one another.

20. The liquid level detecting device according to claim 11 , wherein the preset range is between 0.1˜1.5.