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The manufacture of high quality color CRTs demands high precision registration of a black matrix and three color phosphor coatings on the front panel. The fine structure of the matrix and phosphor dots must be closely controlled or brightness, white balance, and color purity will be lost. We describe here one system which measures the phosphor and matrix patterns on CRT panels before evacuation and sealing, and another system which can estimate electron-beam spot size and color convergence on completed CRTs. Both systems are designed around a commercial vision processor and CCD camera. Both observe about 1/8' areas at 2X magnification, and both have automatic focusing capability. In the CRT panel measuring system, run-length encoding and moments algorithms are used to measure phosphor and matrix parameters and registration to a precision (one sigma) of typically 1 micron, corresponding to a sub-pixel precision of 0.1 pixels. This has been confirmed by a rigorous measurement capability study. Such precision permits process control long before low quality CRTs are produced. In the electron-beam spot size and convergence estimator system, which observes the beams through the internal shadow-mask of the CRT, principal moments ellipses and minimum covering ellipses are used to model electron-beam shape in all three colors. The precision (one sigma) of this system is about 0.05 mm in both spot size and convergence, for spots about 3/4 mm in size. This is comparable to results for the best trained human observer.
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