| 摘要 |
<p>363,194. R÷ntgen-ray apparatus. MœLLER AKT.-GES., C. H. F., 93, Hammerbrookstrasse, Hamburg, Germany. Jan. 28, 1931, No. 2777. Convention date, April 24, 1930. Addition to 339,215, [Class 98 (i), Photographic cameras &c.]. [Class 98. (i).] In apparatus for controlling the exposure in X-ray photography by means of an ionimetric measuring device as described in the parent Specification, a safety device is provided which cuts out the supply to the tube when the highest permissible load in the tube is reached. The safety device comprises a time switch of known type and operates independently of the measuring device but is automatically stopped by the measuring device when the exposure is complete. In the form of time switch shown, a needle 16 rotated by clockwork or like means is connected through a battery 20 to an electromagnet 19. A sliding contact 17 mounted on a conducting bar 18 fixed to the dial 15 of the time switch completes the circuit of the electromagnet when the needle 16 reaches the contact 17. Contacts 25, 26 are provided in the primary circuit of the transformer supplying the X-ray tube, the contact 25 being mounted on an arm 23 bearing an armature 24 co-operating with the electromagnet 19. To stop the time switch when the exposure is complete, a similar circuit comprising a contact piece 28 on a conducting bar 27, an electromagnet 29 and a battery 30 is provided in the measuring device, the electromagnet co-operating with an armature 34 on a bell-crank lever 33 to move a stop into engagement with the mechanism of the time switch when the needle 14 of the device reaches the contact piece 28.</p> |
