Method and system for detecting defects of transparent substrate

1. A system for detecting defects of a transparent substrate, comprising:

a plurality of detection channels, each of which includes an illumination component for providing illumination to the substrate and an imaging component for scanning the substrate to provide image of the substrate;

a transport module, for producing relative motion between the substrate and the illumination components and the imaging components included in the plurality of detection channels; and

a controlling module, for controlling the illumination components and the imaging components included in the plurality of detection channels so that at least two illumination components of the illumination components included in the plurality of detection channels provide illumination to the substrate alternately, and the imaging component included in any of the plurality of detection channels scans the substrate when the illumination component included in that detection channel illuminates the substrate,

wherein the imaging components included in at least two detection channels of the plurality of detections channels are the same imaging component,

wherein, at least two of the illumination components included in the plurality of detection channels are one and the same illumination component so that said same illumination component is shared by two different detection channels of said plurality of detection channels,

wherein the plurality of detection channels includes a first detection channel, a second detection channel, a third detection channel and a fourth detection channel,

wherein the illumination component and the imaging component included in the first detection channel are placed on one side of the substrate, and the illumination component included in the first detection channel provides reflection illumination to the substrate with respect to the imaging component included in the first detection channel,

wherein the imaging component included in the second detection channel is placed on another opposite side of the substrate and the illumination component included in the second detection channel is placed on the one side of the substrate, and the illumination component included in the second detection channel provides transmission illumination to the substrate with respect to the imaging component included in the second detection channel,

wherein the imaging component included in the third detection channel is placed on the one side of the substrate and the illumination component included in the third detection channel is placed on the another opposite side of the substrate, and the illumination component included in the third detection channel provides transmission illumination to the substrate with respect to the imaging component included in the third detection channel,

wherein the illumination component and the imaging component included in the fourth detection channel are placed on the another opposite side of the substrate, and the illumination component included in the fourth detection channel provide reflection illumination to the substrate with respect to the imaging component included in the fourth detection channel,

wherein the imaging components included in the first and third detection channels are one and the same first imaging component and the imaging components included in the second and fourth detection channels are one and the same second imaging component,

wherein the illumination components included in the first and second detection channels are one and the same first illumination component and the illumination components included in the third and fourth detection channels are one and the same second illumination component, and

wherein the controlling module controls the first and second illumination components to illuminate the substrate alternately, and controls the first imaging component and the second imaging component to scan the substrate at the same time when the first illumination component and the second illumination components illuminate the substrate.

2. The system according to claim 1 , wherein

the plurality of detection channels includes at least two of the first detection channels and

the imaging components included in the at least two of the first detection channels are one and the same first imaging component.

3. The system according to claim 1 , further comprising:

an image processing module, for performing image processing on the image of the substrate from each of the plurality of detection channels, to detect defects of the substrate.

4. The system according to claim 1 , wherein

the imaging components included in the plurality of detection channels scan the substantially same zone of the substrate to provide images of the substrate.

5. The system according to claim 1 , wherein

the illumination components included in the plurality of detection channels work in pulse mode.

6. The system according to claim 1 , wherein

the controlling module controls illumination time of each of the illumination components included in the plurality of detection channels and exposure time of each of the imaging components included in the plurality of detection channels so that each of the plurality of detection channels completes scanning of the substrate one time within a working period, the working period being defined as time duration when the substrate moves a certain displacement P/M, where P denotes pixel size of the illumination components, and M denotes imaging magnification of the imaging components.

7. The system according to claim 1 , wherein

the controlling module controls the imaging components included in the plurality of detection channels so that exposure time of a first imaging component of the imaging components when the illumination component included in the same detection channel as the first imaging component provides reflection illumination to the substrate is different from that of a second imaging component of the imaging components when the illumination component included in the same detection channel as the second imaging component provides transmission illumination to the substrate.

8. The system according claim 1 , wherein

each of the illumination components included in the plurality of detection channels are a diffusive illumination component or a collimated illumination component.

9. The system according to claim 1 , wherein

each of the illumination components included in the plurality of detection channels includes a semiconductor light source.

10. The system according to claim 9 , wherein

the semiconductor light source is a light emitting diode or a laser diode.

11. The system according to claim 9 , wherein

the semiconductor light source is a monochromatic light source or a polychromatic light source.

12. The system according to claim 1 , wherein

each of the imaging components included in the plurality of detection channels comprises at least one imaging lens and a line scan photo-detector.

13. The system according to claim 12 , wherein

the at least one imaging lens is selected from a group comprising spherical lenses, aspherical lenses, microlens arrays or diffractive imaging elements.

14. The system according to claim 12 , wherein

the line scan photo-detector includes line scan CCD sensor or line scan CMOS sensor.

15. The system according to claim 12 , wherein

the substrate includes float glass ribbon, raw glass panel, glass substrate of photovoltaic module and glass substrate of flat panel display device.

16. The system according to claim 12 , wherein

the system is capable of detecting and categorizing defects of the substrate, wherein the defects include scratches, stains, tin pick-ups, chips, bubbles, black stones, white stones, and knots.

17. The system according to claim 16 , wherein

the system is capable of discriminating internal defects and surface defects and further determining depth of the defects of the substrate.

18. The system according to claim 16 , wherein

the system is capable of detecting and categorizing the defects of the substrate even with presence of foreign particles on the substrate.

19. The system according to claim 18 , wherein

the substrate is not cleaned.

20. A method for detecting defects of a transparent substrate, comprising:

using a plurality of detection channels to provide images of the substrate, wherein each of the plurality of detection channels includes an illumination component for providing illumination to the substrate and an imaging component for scanning the substrate to provide an image of the substrate;

producing relative motion between the substrate and the illumination components and the imaging components included in the plurality of detection channels; and

controlling the illumination components and the imaging components included in the plurality of detection channels so that all or parts of the illumination components included in the plurality of detection channels provide illumination to the substrate alternately, and the imaging component included in any of the plurality of detection channels scans the substrate when the illumination component included in that detection channel illuminates the substrate,

wherein the imaging components included in at least two detection channels of the plurality of detections channels are the same imaging component,

wherein at least two of the illumination components included in the plurality of detection channels are one and the same illumination component so that said same illumination component is shared by two different detection channels of said plurality of detection channels,

wherein the plurality of detection channels includes a first detection channel, a second detection channel, a third detection channel and a fourth detection channel,

wherein the illumination component and the imaging component included in the first detection channel are placed on one side of the substrate, and the illumination component included in the first detection channel provides reflection illumination to the substrate with respect to the imaging component included in the first detection channel,

wherein the imaging component included in the second detection channel is placed on another opposite side of the substrate and the illumination component included in the second detection channel is placed on the one side of the substrate, and the illumination component included in the second detection channel provides transmission illumination to the substrate with respect to the imaging component included in the second detection channel,

wherein the imaging component included in the third detection channel is placed on the one side of the substrate and the illumination component included in the third detection channel is placed on the another opposite side of the substrate, and the illumination component included in the third detection channel provides transmission illumination to the substrate with respect to the imaging component included in the third detection channel,

wherein the illumination component and the imaging component included in the fourth detection channel are placed on the another opposite side of the substrate, and the illumination component included in the fourth detection channel provide reflection illumination to the substrate with respect to the imaging component included in the fourth detection channel,

wherein the imaging components included in the first and third detection channels are one and the same first imaging component and the imaging components included in the second and fourth detection channels are one and the same second imaging component,

wherein the illumination components included in the first and second detection channels are one and the same first illumination component and the illumination components included in the third and fourth detection channels are one and the same second illumination component, and

wherein the controlling step further comprises controlling the first and second illumination components to illuminate the substrate alternately, and controlling the first imaging component and the second imaging component to scan the substrate at the same time when the first illumination component and the second illumination components illuminate the substrate.

21. The method according to claim 20 , wherein

the plurality of detection channels includes at least two of the first detection channels and

the imaging components included in the at least two of the first detection channels are one and the same first imaging component.

22. The method according to claim 20 , further comprising:

performing image processing on the image of the substrate from each of the plurality of detection channels, to detect defects of the substrate.

23. The method according to claim 20 , wherein

the imaging components included in the plurality of detection channels scan the substantially same zone of the substrate to provide images of the substrate.

24. The method according to claim 20 , wherein

the illumination components included in the plurality of detection channels work in pulse mode.

25. The method according to claim 20 , wherein

the controlling step further comprising controlling illumination time of each of the illumination components included in the plurality of detection channels and exposure time of each of the imaging components included in the plurality of detection channels so that each of the plurality of detection channels completes scanning of the substrate one time within a working period, the working period being defined as time duration when the substrate moves a certain displacement P/M, where P denotes pixel size of the illumination components, and M denotes imaging magnification of the imaging components.

26. The method according to claim 20 , wherein

the controlling step further comprising controlling the imaging components included in the plurality of detection channels so that exposure time of a first imaging component of the imaging components when the illumination component included in the same detection channel as the first imaging component provides reflection illumination to the substrate is different from that of a second imaging component of the imaging components when the illumination component included in the same detection channel as the second imaging component provides transmission illumination to the substrate.

27. The method according to claim 20 , wherein

each of the illumination components included in the plurality of detection channels is a diffusive illumination component or a collimated illumination component.

28. The method according to claim 20 , wherein

each of the illumination components included in the plurality of detection channels includes a semiconductor light source.

29. The method according to claim 28 , wherein

the semiconductor light source is a light emitting diode or a laser diode.

30. The method according to claim 28 , wherein

the semiconductor light source is a monochromatic light source or a polychromatic light source.

31. The method according to claim 20 , wherein

each of the imaging components included in the plurality of detection channels comprises at least one imaging lens and a line scan photo-detector.

32. The method according to claim 31 , wherein

the at least one imaging lens is selected from a group comprising spherical lenses, aspherical lenses, microlens arrays or diffractive imaging elements.

33. The method according to claim 31 , wherein

the line scan photo-detector includes line scan CCD sensor or line scan CMOS sensor.

34. The method according to claim 31 , wherein

the substrate includes float glass ribbon, raw glass panel, glass substrate of photovoltaic module and glass substrate of flat panel display device.

35. The method according to claim 31 , wherein

the method is capable of detecting and categorizing defects of the substrate, wherein the defects include scratches, stains, tin pick-ups, chips, bubbles, black stones, white stones, and knots.

36. The method according to claim 35 , wherein

the method is capable of discriminating internal defects and surface defects and further determining depth of the defects of the substrate.

37. The method according to claim 36 , wherein

the method is capable of detecting and categorizing the defects of the substrate even with presence of foreign particles on the substrate.

38. The method according to claim 36 , wherein

the substrate is not cleaned.