GB1394758A - X-ray apparatus - Google Patents

Abstract

1394758 X-ray apparatus PHILIPS ELECTRONIC & ASSOCIATED INDUSTRIES Ltd 5 Jan 1973 [8 Jan 1972] 738/73 Heading H5R In X-ray apparatus in which a carriage, e.g. for an X-ray tube, is attached to means actuated by a drive unit to move the carriage along a tiltable patient support table having a member measuring its angle of tilt, the attachment means is constructed to initiate a signal switching off the drive unit if it experiences a force exceeding a pre-set value, such as would be produced by collision with the patient, provision being made to compensate for the force arising merely from tilt of the table. As shown, the carriage 12 is movable along the table 1 by a chain 6 which is driven by a motor 4 and is attached to the carriage via an intermediate point 18 of the helical spring 19, 20. The potentiometer 22 on the carriage, with cursor 21 attached to the spring at point 18, provides a signal dependent upon the force acting on the spring point 18, which signal is compensated for the force arising merely from the tilt of the table by a signal indicative of the latter derived from the potentiometer 10, attached to the table, with cursor 11 attached to the table pivot, the two potentiometers being connected to form a Wheatstone bridge circuit (Fig. 3, not shown) the balance of which is disturbed, to provide a switch-off signal, upon movement of spring-point 18 consequent upon a collision. If the carriage movement is controlled by a hand grip 13, variation of the pressure exerted on which controls the acceleration of the carriage, the signal arising from the acceleration of the carriage may be compensated for by coupling the hand grip to the cursors of two additional potentiometers connected in series with potentiometer 22 (Fig. 4, not shown), in which case the switch-off force on the spring is not limited to a value greater than that arising from acceleration of the carriage. In a modified arrangement, Fig. 2, not shown, the carriage is connected to chain 6 at the points 16 and 18, the potentiometer 22 is mounted on the table 1, and the drive motor is freely mounted on the table in a manner permitting tilting, an arm attached to the motor acting as the cursor 21, whereby an unbalance signal for the Wheatstone bridge is produced by a fluctuation in the torque of the drive motor. In an alternative embodiment, Fig. 5, the carriage and its drive mechanism are secured to the shaft 37 which is resiliently mounted at its ends by springs 40 and 41. Switch contacts 43, the position of which is adjusted with the tilt of the table by the lever system 44, 45, are actuated by the projection 42 upon the carriage experiencing an excessive force.