Patent GB-776067-A (GB)
Title: Improvements in or relating to registration detectors for printing machines
Inventor: MILLINGTON GEORGE
IPC: B65H7/08
Filed: 1954-03-19
Abstract: 776,067. Feeding sheets. TILLOTSON & SON, Ltd. June 17, 1955 [March 19, 1954], No. 8012/54. Class 100(1) Accurate sheet-registration on the layboard of a printing-machine is effected by a sheet-detector sheet-detector switch comprising a casing 12 of insulating material, a pivoted arm 10 carrying an element 13, adapted to be deflected by a sheet of paper, and an intermediate wedge-shaped contact 14, the latter co-operating with a fixed contact 15 carried on a member 16 of insulating material to which is attached a screw 21. A nut 22 arranged between a fork 20 is provided for adjusting vertically the member 16 relatively to the arm 10. The contacts 14, 15 are connected by wires to an electric circuit. The arm 10 may be urged by a spring towards the arm 16. A casing support 18 embodying the fork 20 is secured to an L- shaped plate 30 adapted for mounting on the printing-machine, the plate having a trident-shaped lower front portion 32 providing two outer prongs 33 (not shown) which form fixed registration stops for sheets, A front plate 19 of the switch casing supports a screwed rod 40 which passes through a curved paper guide 37 having the upper end abutting a lug 36 on the plate 19 and the lower end shaped to fit between the stop flange 33 of the plate 30. The guide 37 can be adjusted by a nut 41 and spring 42. A sheet smoother comprising a spring steel element 43 is carried by the guide 37. In operation, when a sheet approaches in the direction 45 towards the fixed registra- 'tion stops comprising the prongs 33, it first engages the element 13 to open the switch contacts 14, 15, and then engages the prongs 33. Since the contact 15 can be adjusted lengthwise of the wedge contact 14, the element 13 is adjustable relatively to the sheet stop prongs 33. As applied to a printing-machine wherein the impression and printing cylinders can be tripped relatively to each other when a sheet is mis-registered, there are two front detector switches and one side detector switch FLS, NLS, and SLS, respectively, Fig. 4, an electromagnet solenoid SC mechanically connected to the tripping device, a second solenoid' SB connected to the stopping and braking mechanism, and a cam-operated switch C'S for conditioning the circuit at the appropriate times. A second side detector SLS' may be incorporated and switching means may render either one operative. Pilot lights L1 --- L6 which act as indicators, a manually-operated multi-position switch MS1 - - - MS7, and a relay having contacts A1, A2 and coil A are included. There are two crumpled sheet detectors CSD1, -CSD2, and a second relay having a coil B and contacts B1, B2. There is a voltage-reducing transformer T with its primary winding connected to single-phase A.C. supply lines 50, 51. A buzzer 53, a motor-operated flasher 52, and a push-button switch PB are also included. The multi-position switch MS1 - - - MS7 enables the machine to be set for four conditions:-(1) When an inaccurately registered sheet is detected, the machine continues running, but the sheet is not printed; (2) The absence of a sheet or the presence of a mis-registered sheet is detected and the machine is stopped; (3) A test condition in which the accuracy of the registration can be checked without otherwise affecting the operation of the machine; (4) A further test condition in which there is permanent tripping so that the setting of the sheet-feeder can be tested. The pilot lights and the buzzer 53 give visible and audible warnings of absence of a sheet or inaccurate register. Additional switches to determine the presence of two superposed sheets prior to their being passed to the impression cylinder may be connected in parallel with the switches CSD1, CSD2.