An effective method of shielding an ambient magnetic field in the CRTs is presented. The key to this method is the use of the L-shaped strip iron. The L-shaped pieces are arranged with separation around the frame of the CRT. The new shielding method has the effect of reducing and reshaping the perpendicular field to the screen and reduces the color change. On the other hand, there are no effects from reducing and reshaping the parallel field to the screen.
