| 摘要 |
<p>PURPOSE:To facilitate the alignment of axis while to lengthen the service life and to achieve sufficient brightness, by setting particular relation between the direction of axis and the half top angle at the tip. CONSTITUTION:In a stereo projection, a crystal direction (a, b, c) where the nearest 310 direction is only one is selected as the axial direction of single crystal chip, and when assuming the angle between (a, b, c) direction and the nearest 310 direction is alpha while the angle between (a, b, c) direction and next 310 direction is beta the half top angle at the tip of single crystal chip is selected to be greater than 90 deg.-beta and smaller than 90 deg.-alpha. Consequently at the tip of the chip which is spherical in microscopic, only one (031) face easily emittable the electron beam will appear at the nearest of (a, b, c) face and since the electron beam is emitted only from said face under relatively low temperature the emission pattern and the cross-over shape can be made circular.</p> |
