Application of Three Dimensional Shape from Image Focus in LCD/TFT Displays Manufacturing

One of the fundamental objectives of computer vision is to reconstruct a three-dimensional (3D) structure of objects from two-dimensional (2D) images. Shape from focus (SFF) is the problem of reconstructing the depth of the scene changing actively the optics of the camera until the point of interest is in focus. The point in focus gives information about its depth through the thin lens Gaussian law. Previous SFF algorithms use 2D window for finding the best focused points. In this paper, we propose to use 3D window for finding the best focused points. The new SFF algorithm is applied on the camera mounted microscope for developing an auto-grinding equipment of LCD color filters. In order to develop thin and bright displays, TFT-LCD is used nowadays. In the manufacturing process of TFT-LCD panels, cells and color filters are put together. The protrusion which is generated by combining the two unequal sizes (difference in microns) of glasses in the construction of LCD panels causes a big problem. Therefore, the protrusion is cut to the proper height before the two glasses are put together. Usually, the number of cells in a typical TFT/LCD display is in millions. The time for the checking and cutting of protrusions greatly affects the cost of manufacturing. We, therefore, propose the use of the proposed SFF algorithms for the said problem for fast and accurate process.