Theoretical and experimental techniques in the design of CRT deflection systems

Abstract

This investigation considers the design methodologies associated with the development and optimization of a magnetic deflection system for Cathode Ray Tube (CRT) Display Systems. The development of a magnetic deflection system and the calculations necessary to determine the associated performance are both complex tasks. Their complexity arises from the detailed geometry involved in deflection unit designs, the wide range of product types and sizes, and variability in product performance specifications. The large variations of these issues compound the difficulty in realising an acceptable product design. Software simulation techniques which are able to accurately manipulate data and perform iterative calculations greatly aid this process. This work introduces a simulation technique used within the Philips organisation, called DUCAD (Deflection Unit Computer Aided Design), which is used to analytically and numerically model the deflection system, with the objective of assessing and speedily realising a design. The simulation technique allows magnetic deflection product designs to be synthesized by simulating the magnetic field generated by the deflection system. Approximate solutions can be iteratively investigated leading to a greater understanding of the problem domain. To gain a degree of confidence with the simulation results the software design proposal is thereafter replicated in hardware allowing a full validation of the DUCAD. Extensive simulation studies and practical prototyping experiments are presented to support the theoretical development. Comparing the calculated theoretical performance and the actual measured values, conclusions are drawn as to the quality of the simulation tool in deriving the intrinsic magnetic deflection characteristics of the generated product design. The level of agreement of theoretical prediction and experimental results are defined, and the design methodologies required to yield a slot based deflection system are assessed.