Internal flaw position detecting method in depth direction for glass base plate

Abstract

To enable accurate and quick decision on the quality of a glass substrate, by precisely calculating the position of a defect in the depth direction, based on the image of a defect photographed, while moving the focal surface of a camera from the surface of the glass substrate to the inside, to obtain a clear image of a micro defects. The focal point of the camera is made to coincide with the position of a defect on the surface of the glass substrate; the gradient of illuminance in color in a boundary between the defect and the background thereof is calculated as a gradient index GI value with respect to a traveled distance from the glass surface, by using the image with the defect photographed, while the focal plane of a camera is moved from the surface of the glass substrate to the back side; the traveled distance, corresponding to the maximum of the gradient index GI value is determined as the position of the defect in the depth direction.

Description

technical field [0001] The present invention relates to a method for detecting the position in the depth direction of an internal defect existing in a glass substrate, more specifically, to a method for detecting the position in the depth direction of a defect in a glass substrate. The gradient indicator (Gradient Indicator) calculated by processing the image of the defect captured by the camera while moving the focal plane from the surface of the glass substrate to the inside of the glass substrate is related to the brightness of the illumination, the size, shape, boundary, The position in the depth direction of the defect is accurately calculated regardless of the thickness and the like, and a clear defect image can be obtained from this correct position even for fine defects. Background technique [0002] Generally, on glass substrates used in the manufacture of flat-panel displays such as TFT-LCD, PDP, and EL (Electro-Luminescence), if there are tiny defects such as tiny...

AI Technical Summary

Problems solved by technology

[0007] However, the mechanical image inspection method using a CCD camera has the disadvantage that it can only be applied to the inspection of relatively large defects, and it cannot clearly detect defects smaller than hundreds of microns in the glass substrate.

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