Apparatus for detecting particles in flat glass and detecting method using same

An apparatus for detecting particles in a flat glass in the state of transferring to decide whether the particles contained in the flat glass are benign defects including bubbles or malignant defects including metals, comprising:

• a first photographing device, comprising:
• a first illumination unit which is installed in one region selected from upper and lower regions on the basis of flat glass and which illuminates a light obliquely based on the normal vector of the flat glass;
• a first polarizer which is installed between the illumination unit and the flat glass, and has a first polarization direction;
• a first camera which is installed on the normal vector of the flat glass in the opposite direction where the first illumination unit is installed on the basis of the flat glass and which receives the light diffused by defects;
• and
• a second polarizer which is equipped in a space between the first camera and the flat glass;
• and
• a second photographing device, comprising:
• a second illumination unit which is installed in same region selected from upper and lower regions on the basis of flat glass and which illuminates a light obliquely based on the normal vector of the flat glass;
• a third polarizer which is installed between the second illumination unit and the flat glass, and has a second polarization direction;
• a second camera which is installed on the normal vector of the flat glass in the opposite direction where the second illumination unit is installed on the basis of the flat glass and which receives the light diffused by defects;
• and
• a fourth polarizer which is equipped in a space between the second camera and the flat glass;
• wherein the first polarizer and the second polarizer have different polarization directions in the range of 0° to 20°, and the third polarizer and the fourth polarizer have different polarization directions in the range of 70° to 90°,
• wherein the light illuminated from the first illumination unit and the second illumination unit does not enter directly to the first camera and the second camera respectively, and the light being obliquely illuminated from the first illumination unit and the second illumination unit directly to the first polarizer and the third polarizer, respectively, and directly from the first polarizer and the third polarizer to the flat glass.