Patent GB-710385-A (GB)
Title: Improvements in prompting system
IPC: H04N5/222
Filed: 1952-03-21
Abstract: 710,385. Changing signs. TELEPROMPTER CORPORATION. March 21, 1952 [April 6, 1951], No. 7364/52. Class 3(1) [Also in Group XXXVII] A prompting system comprises a control unit 8 and a plurality of script repeating units 101 electrically connected thereto, each of the script units including a script sheet 100, a plurality of discontinuities disposed lengthwise of the sheet and a pair of contact members forming with other discontinuities successively a plurality of switches upon passage of the discontinuities past the contact members, the control unit including a plurality of means responsive to the formation of any one of the switches in one of the script repeating units to interrupt energization of the driving motor of said one script repeating unit until all of said driving motors have been de-energized and means responsive to the de-energization of the last of the driving motors to restore all of them to the energized condition. The units 101 each consist of a casing containing a frame 106 which supports two. rollers 107 acting as supply and take up rollers for the script sheet 100. The sheet passes over guide rollers 108 behind an. aperture and lamps may be provided at the sides of the opening to illuminate the sheet. The sheet is provided with a backing board 109 behind the aperture to enable corrections to the script to be made and this backing board has a transverse slit 110 so that portion may be easily cut out from the sheet. The rollers are mounted so as to be quickly detachable from the frame. Either of the rollers 107 can be driven from a motor 134 through a reversing mechanism consisting of a pinion 148 which is driven by the motor through a flexible shaft and which is mounted on a pivoted arm 146 so that it can drive either one roller or the other. The arm 146 is moved from one position to the other by a cam 164 driven by a motor 160 and an additional cam 166 on the same shaft operates a changeover switch 170 in the circuit of the cam motor 160 to stop the motor after the cams have rotated 180 degrees and to prepare a circuit to the reversing switch in the control unit so that when the switch is returned to its initial position the cams will make a further 180- degree rotation to reverse the rollers once more. The motors 134 are of the threephase self-synchronous type and their stator windings are paralleled across the output of a three-phase generator 407 in the control unit. The rotors of the motors and generator are connected in parallel across an A.C. supply and hence the motors keep in step, but to keep the sheets' in step irrespective cf variations in the length of a given amount of script, means are provided to stop at intervals automatically the driving motors of units having relatively short lengths of script until the unit having the longest length catches up. This is accomplished by the discontinuities which consists of conducting strips 182 at predetermined intervals which bridge two brushes 180 forming the contact members and by means of relays in the control unit, two of which 419, 427 are provided for each unit 101, the corresponding driving motor is stopped. Relay 427 which is self-locking is actuated when a strip 182 connects the two brushes and this relay in turn prepares a circuit through contact 435 for its associated relay 419. The circuit, for each relay 419 is completed through a cam-operated switch 443; this switch is on the shaft of the three-phase generator 407 which feeds the stators o,f the motors 134 and the switch 443 is made once in each revolution of the generator. When it makes, any of the relays 419 whose operating circuit has been prepared by its relay 427, is actuated and the stator circuit of the associated motor 134 is broken, relay 419 locking to the supply through make-before-break contact 403 to hold the motor inoperative and at the same time preparing a circuit through contact 452 for a reset relay 446. The use of cam switch 443 ensures that the motors will stop with their rotors at the same orientation. The contacts 452 or the relays 419 are connected in series so that all the re-' Jays 419 must be operated and consequently all the motors 134 must be stopped before the reset relay 446 can operate. The circuit for this relay is completed through a camoperated switch 458 also actuated at every revolution of the generator shaft, the cam being designed to close the switch 458 before switch 443 is actuated by its cam and to keep it closed for a period after the release of switch 443, consequently immediately the last relay 418 is actuated by a switch 443, the circuit of the reset relay is completed and it is actuated. This actuation closes contact 448 to by-pass contacts 452, breaks the supply to relays 427, 419 through contact 434 so that they release and allow the motors 134 to operate and also breaks the circuit of switch 443; this permits the brushes 180 to clear the strips 182 and prevent operation of relays 427, 419 until switch 418 is broken by its cam to release relay 446. The relays 419 are provided with a pilot light to indicate when they are operated and each unit 101 has an on/off switch 423 in the control unit which in the "off" position locks operated the corresponding relays 427, 419, independently of the action of the reset r'elay 446. A switch 12 is provided to disable the reset relay and change the supply circuit of the relays 427 so that the motors 134 can only be stopped and started by the action of the switches 423. The cam switch 443 is still operative in this condition to stop the motors with their rotors at the same orientation. A remote control uni 30 which can be plugged into the control unit 8 or any of the units 101 enables the operator to stop all the drive motors together, by operating a switch 33 which is connected in the armature circuit of a D.C. motor 413 which drives the generator 407 supplying the motors 134. A variable resistance 14<SP>1</SP> in the remote control unit or a similar resistance 14 in the control unit can be connected in the armature circuit of the D.C. motor 413 to enable simultaneous changes in the speed of the motors 134 to be made. The remote control unit has a switch 34 for simultaneously operating the reversing motors 160 and a switch 35 operates a cue light 113 on each unit 101.