GB536641A - Improvements in or relating to control devices for kinematograh machines associated with e.g. kinematograph targets - Google Patents

Abstract

536,641. Kinematograph targets. MACDONALD, A. E., and THOMSON, W. J. Aug. 17, 1939, No. 23766. [Class 20 (i) 1 [Also in Group XX] An arresting mechanism, operative on a kinematograph projector or on a moving picturecarrier at a pre-determined time after a selected moment, comprises a control member movable from a starting position to an arresting position, means for relatively adjusting these positions, and means operated by the control member at the arresting position to arrest the projector &c. the lapse of time being pre-determined by the distance between the starting and arresting positions of the control member. Fig 1 shows target apparatus comprising a kinematograph projector 21, a projection screen consisting of two layers 15 of a band wound on rollers 14 and on spools 11, 12, and a control apparatus in a casing 22. Where a switch 19 is momentarily closed by impact of a bullet on a movable plate 13, the control apparatus acts, firstly, to stop the projector after an adjustable time calculated as that necessary for the bullet to reach the object arrived at if the object were actually at the range it apparently has in the projected picture, secondly, to light lamps 23 behind the screen 15, thirdly to energize a motor 13 rotating the spool 12 to move the layers 15 in opposite directions, thus obliterating the bullet holes, and finally, to restart the projector and itself assume a condition ready for the next shot. The control apparatus comprises a continuously-driven spindle 49 carrying a worm 48 which is normally inoperative but is brought into engagement with teeth on a control member in the form of the cam-carrying disc 41 only when a solenoid 68 has been energized by closure of the switch 19. Rotation of the disc 41 stresses a coil spring 75, and cams 42, 43 on the disc respectively, after an interval raise a follower 72 to stop the projector, and, after a further interval, raise a follower 45 to energize the motor 13. The follower 72 is carried by a spring-pressed crank 70 to which a rod 69 is pivoted ; the rod operates a clutch in the drive for the projector, through a Bowden connection, and also operates a switch 73 in the circuit of the lamps 23 to light the lamps simultaneously with stoppage of the projector. The follower 45 is carried by a plate 60 on a fixed pivot 59, and the plate is connected by a link 61 to a switch 74 in the circuit of the motor 13, so that, when the plate is turned by the cam 43, the switch is closed against the action of a spring 77. The pin 59 also carries a spring- urged catch 58 having a notch which engages the end of a plate 56 on a bracket 50 mounted on a pivot 51 and carrying the worm 48, the engagement keeps the worm in mesh with the disc 41. Engagement is effected when, upon the momentary closure of the switch 19, the solenoid is energized to attract its armature 67 and turn a plate 64 about a fixed pivot 65, thus lifting the bracket by a roller 63 on the plate 64. Disengagement is effected by contact of the cam 43 with the tail end of the catch 58, thus permitting the worm to fall out of mesh with the disc 41, and stopping the drive. The freed disc is then returned to its initial position by the spring 75 and projection proceeds as before. Adjustment of the time at which the cam 42 becomes operative is effected by means of a knob 36 on a spindle carrying a worm 33 meshing with teeth on a disc 29 rigidly connected to a dial 28. The disc 29 carries a spring-mounted plunger which engages a pin 46 extending from the disc 41, and its rotation turns the disc 41 to alter the starting position for the drive between the worm 48 and the disc 41 ; this position is indicated by a scale on the dial 28. If the target consists of a picture on a moving carrier, the carrier may be stationary at the time of firing, and the impact of the bullet on a back plate may set in motion both the carrier and the control member. Specification 519,948 is referred to.