Abstract
With regard to the CRT display, the deflection yoke is required to achieve higher picture quality. To achieve it, we currently use the ferrite core of which inner surface was ground. The picture quality is closely related to the inside diameter of the ferrite core. Therefore, we made a study on the heat shrinkage of the ferrite core to be used for the saddle-saddle type deflection yoke. We are reporting here the method of reducing the shrinkage of the ferrite core to improve the accuracy of its inside diameter. With a view to achieving higher bulk density (BD), we selected optimum iron oxide out of main materials in various conditions and improved both the uniformity of the diffusion of polyvinyl alcohol (PVA) and the particle size distribution. As a result, we could reduce the shrinkage of the ferrite core from 14.5% to 10.0%. By this method, we could achieve the same performance of the deflection yoke as in the case of the ferrite core of which inner surface was ground.
