Patent GB-1234168-A (GB)
IPC: B41J7/36
Filed: 1969-08-12
Abstract: 1,234,168. Selective printing. SPERRY RAND CORP. 12 Aug., 1969 [27 Aug., 1968], No. 40300/69. Heading B6F. [Also in Divisions G4-G6] A high speed printer comprises a rotating type wheel having characters arranged in columns and rows, each row containing all the same characters, translating means electrically coupled to the type wheel giving a coded signal indicating which row is approaching the printing position, a register for temporarily storing each unit of data to be printed, a comparator connected to said translating means and to the register providing a comparison signal for each entry in the register which matches the coded signal, a print mechanism having a print hammer for each column of the type wheel, connected for operation to the comparator so that when the type wheel has completed one revolution each row character has been compared with all the units of data to be printed. Data e.g. from a  desk calculator 56 is stored in a register 57  forming part of the recirculating store of the calculator. When a read out is required, the register 57 is filled and isolated the recirculating loop of the calculator being completed by line  59. Each character is represented by 4 binary bits. A disc 50 rotating with the type wheel has holes 61 sensed by a photo-cell and the signals are applied through a delay flop 64 to a counter 65 which advances one count for each row. The output of the counter is compared at 60 with the output of the register and agreement enables a number of AND gates in scanner 67. The scanner is controlled by a shift counter 68 incremented by the digits as they are entered into register 57. When the shift counter has a count of one and the comparator shows agreement, the first print solenoid 15 is energized. The next least significant digit energizes the next solenoid 14 and so on. The counter 65 is reset by a double length interval between the holes corresponding to the decimal point row and the "0" digit row. Delay flop 64 responds to this interval to reset counter 65 to start counting again at the "0" row. When a solenoid 45 is energized, the corresponding hammer is operated by the mechanism shown in Fig. 2. Solenoid 45 displaces lever 46 against the action of spring 47 to rotate a trigger 40 in a clockwise direction by bearing against the arm 42. Arm 41 then slips out from behind a detent 32 on a pawl carrier. A pawl 35 is pivoted to the pawl carrier at 36 and has a tooth 39 extending upwardly through slots in actuator 17 and tube 14. When the pawl carrier is released the tooth rises to be engaged by one of the spline teeth 13 of shaft 11. This shaft is driven at twice the speed of the type wheel so that twelve teeth pass the pawl tooth for each rotation of the type wheel. All the characters in register 57 are scanned in turn and all the 0's cause the corresponding pawls to rise to the operative position for engagement by the next spline tooth 13. All the operated pawls are simultaneously engaged by this tooth and the corresponding actuators 17 rotated until the pawl teeth 39 meet the edge 44 of the slot 15 in the tube 14. The pawls are then cammed out of the slot and the mechanism resets to its original position. As an actuator rotates link 25, pivoted to it at 26, rotates the arm 27 to bring the hammer 28 against the paper 69 and cause printing. The impact of the hammer may be cushioned by engagement between abutment 54 and spring 53. The spring is adjustable to set the striking pressure of the hammer.