| 摘要 |
<p>PURPOSE:To make a tensely installed state maintainable to a ribbony heater at all times, forming a tensile installed supporting body of the ribbony heater from a movable member with spring elasticity. CONSTITUTION:In the upper part of a ceramic insulator 20, there is provided with a ribbony heater 22 coated with emitter material 21 at the central part in a state of being opposed to a first grid electrode (unillustrated herein). And, in this ribbony heater 22 bending points 22b and 22b situated inner side as far as the specified distance from its base ends 22a and 22a are touchingly supported by upper end edges 23a and 23a of a ceramic plate spring of a movable member 23, having spring elasticity, tightly attached to a side part 20a of the insulator 20. With this constitutin, an almost horizontal, double end support beamlike supporting form can be obtained.</p> |
