DIRECT VIEWING STORAGE TUBE HAVING MESH HALFTONE TARGET AND NONMESH BISTABLE TARGET

摘要

A direct viewing charge image storage tube is described in which a low density halftone storage target is employed along with a higher density bistable storage target. Charge images are written on the halftone target at a fast writing speed, up to about 300 million centimeters per second, and then such charge image is transferred to the bistable target where it is stored for a long time, up to one hour or more. The bistable storage target may be of the nonmesh type that employs a storage dielectric of phosphor material which emits a light image corresponding to the charge image stored thereon. The storage dielectric of a halftone target is more porous and lower density than the phosphor storage dielectric and may be a porous metal oxide, such as magnesium oxide, having a density of 2 to 5 percent of its normal bulk density which provides a target of low capacitance and extremely fast writing speed.