| 摘要 |
<p>In the control of the distance of an object from a moving surface from which hyperfrequency waves are reflected, a radiation director is disposed opposite the surface, the director supplying hyperfrequency waves ad being fixed in respect to the objecT. Simultaneously radiation reflected from the surface is received by the director and the phase of the emitted wave is compared with that of the reflected wave. An error signal resulting from the compsn. is used to maintain the distance at a predetermined value which is a multiple of a quarter of a hyperfrequency wave. The invention is suitable for controlling the distance of a welding torch from a workpiece enabling the adoption of automatic welding apparatus suitable to all welding conditions.</p> |
