Patent GB-710311-A (GB)
Title: Improvements in change-over apparatus for motion picture projectors
IPC: G03B31/02
Filed: 1952-04-22
Abstract: 710,311. Kinematograph apparatus. BAUER GES, E. April 22, 1952 [April 23, 1951], No. 10061/52. Class 97(1) A change-over apparatus comprises, on each projection, a light shutter, a movable stop member for holding the shutter in the open position, an electro-magnet having its armature connected with the stop member, a sliding bolt for moving the shutter and a switch adapted to be actuated by the bolt and connected with the electromagnet of a second projector, in which the bolt consists of two parts coupled together, one part of which at first actuates the switch only, to energize the electromagnet of the second projector and so actuate the stop member thereof and release the shutter to close it and subsequently engages the second part which opens the shutter of the first projector. The device shown is located between the lamphouse and film gate, the projection beam passing through the aperture 3. A piston 10, on a bolt 9, slides in a cylinder 8. Two collars 21, 25 are connected by a rod 24 and are slidable on the bolt 9. A spring 27 urges them to the right to the extent permitted by a transverse pin 22 through the collar 21 and a slot 23 in the bolt 9. In the running position shown a groove 18 in the piston 10 connects ports 16 and 17 to supply compressed cooling air to the lamphouse. A groove 43 connects the port 16 with the cylinder 8. The pivoted shutter 12 carries a pin 13 between pins 14 and 15 projecting from the bolt 9. The shutter is held clear of the light path by a stop member 46 carried on a shaft 45 in a pivot 44. Actuation of a switch 39 on the other projector, when started, energizes an electromagnet 50 which, acting through a pin 47, retracts the stop 46 so that the shutter drops to cover the aperture 3 and slides the bolt to cut off the air supply to the port 17. The air in the cylinder 8, initially compressed, at first assists the shutter movement and then acts as a dashpot to damp it. As the bolt slides a cam 26 on the collar 25 allows a follower roller 33 to drop and a lever 29, coupled to the roller through a link 32, to rotate about its pivot 28 to actuate a mercury switch 35 to extinguish the sound exciter lamp. A lever 37, pivoted to the lever 29 at 36, slides on a pin 40 until a notch 38 engages the pin. The pin is carried on a lever 30, also carried on the pivoted 28, acted on by a spring 41 and carrying a mercury switch 39. To restart the projector the button' 20 is depressed and this, through the pin 19, at first only slides the collars 21, 25 so that the cam 26 lifts the roller 33 and the link 32 to rotate the lever system 29, 37, 30 to operate the mercury switches 35, 39 respectively to light the exciter lamp and transmit an impulse to the electromagnet 50 of the other projector to close its shutter. The lever 37 engages a stop 42 and is caused, as the movement continues to release the pin 40 from the notch 38 to allow the lever 30 to return to its initial position. The last part of the movement of the button 20 compresses the spring 27 to move the bolt 9 and lift the shutter 12. During this movement the roller 33 is on a horizontal part of the cam 26. The sliding bolt may be arranged so as not to be operable if the projector motor is not running or if the cooling air supply fails. The shutter may be closed by film breakage.