<title>Improving display quality by a digital convergence correction system for multibeam CRTs</title>

In the field of medical imaging there is a need for high-resolution high-brilliance monochromatic CRT displays. However, at higher brightness levels the resolution of these displays decreases, due to the increasing spot size. In order to improve the performance of the CRT display a relatively simple method, called the multi-beam concept, is introduced. Using this technique a higher brightness can be realized without an increase of the spot size and therefore a better display quality can be achieved. However, for successful exploitation of the multi-beam concept it is necessary to minimize the convergence error of the CRT display. For this purpose two circuits have been realized, where the convergence error is reduced by an analogue and a digital method respectively. The analogue implementation means an improvement for the applicability of the multi-beam concept, however, in order to achieve major image quality improvement the use of the digital system is necessary