It has been shown that carbon nanotubes exhibit good electron field emission properties, therefore have potential application in field emission displays as electron field emitters. In this study, the authors propose a new coplanar printed carbon nanotube (CNT) field emitter design that possesses symmetrical self-focusing properties without adding a focusing gate. A cylindrical gate electrode is located at the center and surrounded by the cathode. CNT-paste can be applied to the cathode surface near or on the corner. A two-dimensional, particle-in-cell computer simulation code MAGIC was used to investigate the field emission characteristics of this new type of field emitter. Simulations were carried out for different gate voltages to investigate the effects on the emission current and beam divergence. Typical simulation parameters are anode voltage of 1000 V, cathode voltage of 0 V, and an anode-cathode distance of 95 mu m. It was found that there is an optimum gate voltage that gives the best focusing effect. The optimum gate voltages are different for different CNT paste locations. For CNT paste located on the round corner, with a radius of curvature of 0.5 mu m, an optimum negative gate voltage of about -15 V is needed to push the overfocused emitted electrons to a focused spot having a current-weighted beam radius of 2.1 mu m. For a ring of CNT paste with I mu m width located on the flat surface next to the corner of the cathode, it would require an optimum gate voltage of about 45 V to attract the emitted electrons to fall on a single spot on the anode having a current-weighted beam radius of 1.6 mu m. The electron emission can be turned off on individual emitter by applying a large negative gate voltage. This study shows the proposed simple field emitter design can produce well-focused electron beams for high resolution display applications. (c) 2007 American Vacuum Society