Study of macro-lenses versus micro-lenses using emittance concept for field emission displays

Summary form only given. Electrons emitted from conical shaped tips of gated field-emitter arrays (FEAs) have a wide angular spread, which can be as large as /spl plusmn/40/spl deg/. This will result in large pixel sizes or pixel cross talk in a field emission display (FED) without lenses for high voltage phosphor applications. Emittance in the x-direction, /spl epsiv//sub x/, is defined as the area occupied by the electron beam in the x-/spl theta//sub x/ phase space divided by /spl pi/, where x is the position of the electron beam, and /spl theta//sub x/=v/sub x//v/sub z/, where v/sub x/ and v/sub z/ are the velocities in the x and z directions, respectively. The beam focusing and collimation can best be understood using the emittance diagram. A smaller focusing spot can be obtained from beams with smaller emittance. A lens with one opening encompassing all the electrons from a pixel of an FEA is called a macro-lens in this paper. Field emission display companies such as Raytheon and Candescent Technology Corp. use macro-lenses. Lenses fabricated on the FEA wafer with one opening encircling one tip is called an integrated micro-lens in this paper. Currently, no FED companies are applying this approach. Emittance diagram can be used to explain the capabilities and limitations of various concepts to obtain desirable pixel resolution for FED applications.