| 摘要 |
<p>357,439. Rontgen ray apparatus. BRITISH THOMSON-HOUSTON CO., Ltd., Crown House, Aldwych, London.-(Assignees of Kearsley, W. K. ; 1606, Randolph Road, Schenectady, New York, U.S.A.) Dec. 12, 1930, No. 37547. Convention date, June 23. [Class 98 (i).] A time switch for controlling the period of energization of X-ray apparatus comprises an electric motor rotating a contact drum adapted to co-operate with contacts spaced apart lengthwise of and adjacent to the drum, means driven by the motor for moving the contacts lengthwise of the contact drum and means for rendering the last means active for moving the contacts on to the surface of the drum. A synchronous electric motor 10, driven from alternating current mains 10<1>, drives a shaft 11 through variable speed gearing 18. The shaft 11 carries a contact cylinder having a central conducting portion 16 and insulating ends 14, 15, the dividing line between the insulating and conducting parts being a stepped spiral of the same pitch as a screw 17 also on the shaft 11. A carrier 27 can slide but not rotate on a shaft 21 to which is attached a lever 24, having at one end an armature 23. On energizing an electromagnet 22 by means of a push-button 26, the armature 23 is attracted and the shaft 21 is rotated. This causes the end of a lever 28 on the carrier 27 to engage the screw thread 17 and the carrier slides to the right. At the same time, contacts on arms 31, 32 engage the contact cylinder and their distance apart determines the time during which they are both on the conducting segment 16. In this position the X-ray apparatus is energized. The period of actuation is varied by movement of the arm 32 relative to a rack 39 which is provided with a scale 40, and also by means of the variable speed gearing 18. A coupling 13 is provided in the shaft 11 so as to alter the phase at which the break occurs and is adjusted to give a break at the zero of the alternating current cycle. A spring 35 returns the carrier 27 to its starting position when the magnet 22 is de-energized, and a latch 44 is provided to hold the carrier 33 in the event of its passing the end of the screw 17 with the magnet 22 still energized.</p> |
