Electric lamp and discharge devices – Discharge devices having a thermionic or emissive cathode
Reexamination Certificate
2003-01-24
2004-10-26
Patel, Vip (Department: 2879)
Electric lamp and discharge devices
Discharge devices having a thermionic or emissive cathode
C313S495000, C313S147000, C378S122000
Reexamination Certificate
active
06809465
ABSTRACT:
FIELD OF INVENTION
The present invention relates to electron beam sources and, in particular, to electron beam sources utilizing micro-electro-mechanical-systems (MEMS) devices and to methods for making the same. The invention is particularly useful for electron beam displays and for x-ray imaging.
BACKGROUND OF THE INVENTION
Display devices play important roles in modern information and entertainment technologies such as computer monitors and TVs. The resolution requirement for typical computer monitors and TV screens is relatively modest, as human eyes can not resolve images finer than ~100 micrometers. For display devices that humans will see at closer distances, for example, head-mounted displays, camera viewfinders, or wearable personal computing devices, a much higher resolution on the order of ~3 micrometers is required. These head-mounted displays allow the free use of hands, and are thus useful for a number of unique applications such as a mobile wearable computer, a head-mounted display for detecting land mines, virtual reality traveling, or remotely guiding mechanical repair or even a surgical operation.
To provide a two-dimensional e-beam source, parallel beam illumination has to take place simultaneously at many different locations on the surface to be exposed. Two-dimensional, x-y addressable array of electron field emission sources include the cold tip cathode array described by C. A. Spindt, C. E. Holland, A. Rosengreen, and I. Brodie, in “Field emitter array development for high frequency operation,”
J. Vac. Sci. Technol. B
, vol. 11, pp. 468-473, 1993, and the nanotube field emission display cathodes described by W. B. Choi, et al. in “Carbon-Nanotube Based Field-Emission Displays for Large Area and Color Applications”,
Journal of Information Display
, Vol. 1, No. 1, p. 59, December 2000. In theory such arrays may be used to achieve simultaneous supply of various e-beams. However, it would be impractical to make each cold cathode structure sufficiently small (on the order of ~10-1000 nanometers) to obtain a display with a 10-1000 nm resolution. Even if such a nanoscale cathode structure would be fabricated, the number of cathode cells and associated lead wires required for x-y addressing would be astronomical. To produce a two-dimensional e-beam array for a display size of 12×12 inch area, it would take about 10
12
~10
14
cathodes and wire connections. The fabrication of display devices having ~3 micrometer pixel display cell size, as compared to the present cell size of ~100 micrometers or larger, would be significantly more complex and expensive. Accordingly it would be desirable to be able to design and fabricate such high resolution display devices by using industrially viable and inexpensive techniques.
SUMMARY OF THE INVENTION
In accordance with the invention, an electron beam source for exposing selected portions of a surface to electrons comprises a plurality of nanoscale electron emitters and, associated with each electron emitter, a directional control element to direct the emitter toward a selected portion of the surface. In a preferred embodiment, the emitters are nanotubes or nanowires mounted on electrostatically controlled MEMS directional control elements. An alternative embodiment uses electrode directional control elements.
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patent: 6545425 (2003-04-01), Victor
Lowenstein & Sandler PC
Patel Vip
Zimmerman Glenn
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