GB1438408A - Multiple electron beam and electron mirror memory apparatus and method - Google Patents

Abstract

1438408 Cathode ray storage tubes MINNESOTA MINING & MFG CO 28 Dec 1973 [2 Jan 1973] 60053/73 Heading H1D Electron beam storage and retrieval apparatus includes electron source 4, magnetic prism 10, first electron storage mirror 6 which is electrically biased during the write mode to allow electron impingement at one of a plurality of storage areas determined by deflectors 19, 20 and is electrically biased during the read mode to modify the density of presented electrons in accordance with stored charges, and read-out means 12 for receiving electrons subsequent to the storage mirror during reading, source 4 being capable of producing a plurality of beams and control means ensuring all beams are presented during reading and selected ones during writing. More than one storage mirror may be included (e.g. mirror 8) allowing redundant storage for example. Fig. 1 also includes three element focusing lenses 13, 14, 15, 16, which also modify the cross-sectional size of the beam array, and objective lenses 18, 21 (e.g. three element and multi-apertured). Various sequences of operation are discussed for the double storage mirror system. Read-out array 12 may be a diode matrix with diodes connected individually, and in a row or in a column. The beam source of Fig. 2 (not shown) includes cathode (28), which may be a cold cathode and may have a radio-active or photoemissive surface, or may be a semi-conductor array (e.g. forward biased Si P-N junctions), and may have apertured masks (30), (60) and (90), and finger electrode control members (32), (33). The finger electrodes are on each side of an insulator base and joined by a conductive layer about the apertures. The writing beams may be controlled row by row or singly. Control of beams from photo-emissive elements may be by using an input light image corresponding to the information, formed by a neon light or LED array. In Fig. 3 (not shown) light sources (49) are focused on to photo-emissive elements (48). The source may alternatively be an array of field emitters (Figs. 4, 5, not shown) including emitting sites (50) in rows on separate emitting surfaces (51) on insulator substrate (52), insulating spacer (53) and parallel spaced accelerating surfaces (54) of thin foils or films of metal in crossed array permitting selective operation. The storage surface of mirrors 6, 8 may be a dielectric thin film (e.g. bismuth titanate, aluminium oxide or silicon dioxide) on a conducting substrate (e.g. a Si wafer). Prism 10 may be Helmholtz coils. Biasing of the outer three plates of lenses 18, 21 control cross-sectional area and the lens plates are positioned at one end of a tubular non-conducting sleeve (e.g. glass) (not shown). The innermost (fourth) plate removes stray electrons and is not biased. The patterns in the four plates are hexagonal. The above glass sleeve may also support the deflector units which may each be eight graphite coatings. Voltages and structural dimensions of the system are given. Operation may be at 10-8 torr.