Patent ID: 7515851
Filing Date: 2009-04-07
Classification: G03G

Abstract:
1. An electron emitter for emitting electrons into a surrounding atmosphere toward a counter electrode disposed in opposing, spaced apart relation thereto, said electron emitter comprising an electron emitting element having a semiconductor layer formed between a first electrode and a second electrode, at least part of a surface of said semiconductor layer on a side of said first electrode being porous, characterized in that a power supply is provided for alternately applying a positive voltage and a negative voltage having an opposite polarity to said positive voltage to said first electrode, said positive voltage being at least sufficient to enable electron emission, wherein said electron emitter is further characterized in that an absolute value of a minimum magnitude of said negative voltage, which gives rise to a minimum negative current flow in said electron emitter, is at least 1.5 times as large as an absolute value of a minimum magnitude of said positive voltage, which gives rise to a minimum positive current flow in said electron emitter.