During the manufacture and assembly of electronic display devices such as for example cathode ray tube (CRT) assemblies for computer monitors and television sets, precise mechanical, magnetic and electronic adjustments are required to ensure the electronic display devices provide optimum reproduction image quality. These adjustments include, but are not limited to, focus, purity of color, convergence of beams, color uniformity, geometry and luminance.
In today's computer environment, high resolution electronic display devices are required and therefore, during manufacture it is necessary to ensure the electronic display devices provide high resolution and image quality. This has made visual inspection of electronic display devices to evaluate resolution and image quality unsatisfactory.
Focus and convergence errors in electronic display devices, which decreases resolution and image quality, are a result of deviations in the profile of the electron beams. Therefore, during testing it is necessary to measure electron beam profile so that focus and convergence corrective measures can be taken. Unfortunately, precise measurement of convergence and focus of electron beams in electronic display devices is hampered by the shadow mask and either the phosphor stripes or phosphor dots therein.
methods to measure electron beam profile in an electronic display device are known. For example, Minolta has developed a CB-150 system to analyze focus in an electronic display device by measuring electron beam profile. The system includes a processing unit having a built in video generator, a measuring head and a personal computer. In operation, an electron beam is generated within the electronic display device and the light emitted by three phosphor lines within the electronic display device is detected by a CCD camera in the measuring head. The electron beam is then shifted to the left by 80 .mu.m and the light emitted by the three phosphor lines is detected by the CCD camera again. Thereafter, the electron beam is shifted to the right by 160 .mu.m and the light emitted by the three phosphor lines is detected by the CCD camera yet again. By shifting the electron beam and measuring the color output of the phosphor lines, the profile of the electron beam, which is hidden by the separation of the phosphor lines, can be approximated.
Although this system allows the electron beam profile to be measured to evaluate focus in an electronic display device, the system is slow inhibiting electron beam profile measurements to be made in real time. Accordingly, an improved method and system of measuring electron beam profile in an electronic display device is desired.
It is therefore an object of the present invention to provide a novel method and system for measuring electron beam profile to evaluate focus and/or convergence in an electronic display device.