Abstract: Charge Control Agents In Display Media. Use of charge control agents in display media comprising bichromal elements increases the ability to control translation and rotation of spherical elements in their cavities more precisely, thus yielding sharper and clearer images and longer life at lower applied voltages.

Abstract: The bichromal element spinner apparatus provides the forming of substantially spherical bichromal elements from pigmented molten, but hardenable material compounds which are delivered centrally to a spinning webbed disk through opposite ends of hollow shaft that also spins with the disk. The molten materials are injected into cavities formed between the shaft and the web portions of the disk such that the molten materials are spun outwardly on the opposite surfaces of the disk towards the tip of the disk, where the hardenable materials adhere to each other without mixing, thereby spinning off to bichromal elements. Shrouds attached to the shaft and having no intervening support members over the spinning disk provide quiescent air mass between the disk and the shrouds so as to yield bichromal elements with substantial hemispherical integrity.