Patent GB-1237528-A (GB)
Title: Printer
IPC: G06K15/08
Filed: 1969-12-08
Abstract: 1,237,528. Selective printing. SPERRY RAND CORP. 8 Dec., 1969 [9 Dec., 1968], No. 59795/69. Heading B6F. [Also in Divisions G4-G6] A printer for printing characters successively along a printing line comprises a type wheel 19, Fig. 1, having characters arranged in a helix on its rim and arranged to move along as it rotates so that every character in turn passes over each printing position, circuit means for generating a motion control signal whenever a character is to be printed and a clutch mechanism responsive to the motion control signal causing forward motion of the type wheel along the printing line during a complete revolution. The type wheel is slidably mounted on shaft 28 and connected to it by key way 29. Shaft 28 and a lead screw 20 are driven by motor 34 by belt 32. Carriage 14 sliding on guides 12, 13 is coupled to the lead screw by solenoid 18 which draws pawl 21 into engagement with the screw. Carriage 14 is then displaced as the screw rotates. A cable connects the carriage to the print wheel so that the print wheel moves with the carriage against the action of a spring 43. A pawl 24 on the carriage coacts with a ratchet 27 to prevent backward motion. At the end of the line solenoid 17 releases pawl 24 to allow the carriage to return to the starting position. Data to be printed arrives on parallel leads 50a, Fig. 2 a character at a time. Each character in turn is gated into store 50 by gates 52 under the control of a LOAD signal derived from the input equipment. Later in the rotation of the type wheel the character is transferred by gates 54 to a second store 51 where it is held for one revolution of the print wheel, during which it is printed. For this purpose the output of the store 51 is compared at 57 with the output of sprocket counter 58 which receives pulses from a wheel 35 rotating with the type wheel and carrying magnetic marks sensed by head 36. Counter 58 indicates the character coming into the printing position. When the comparator indicates agreement a pulse is sent to solenoid 15 to operate the hammer. Gate 60 also receives a CR signal from carriage return flip-flop 63 indicating that the carriage is not in process of returning to the start position. The other input to gate 60 is the MC signal indicating that the Move Carriage flip-flop 70 is set, causing solenoid 18 to be operated to couple the pawl 21 to the lead screw 20. The carriage return flip-flop may be set by a carriage return key 66, by a switch 45 at the right hand end of the carriage stroke or by a Carriage return character in the input. This is detected by unit 68. The set output of flip-flop 63 energizes solenoid 17 to release pawl 24. As each character is entered into store 50 the LOAD signal sets flip-flop 73 to give a FULL signal. This is applied to AND gate 71 to set the Move Carriage flip-flop. The printer can therefore be used in two ways: either it will print single characters and stop after each printing operation or it will print a succession if a new character is entered into store 50 during each revolution the type wheel. If no new character is received, the LOAD flip-flop is reset by signal LE (one per revolution) and the Move Carriage flip-flop 70 will reset disengaging the pawl 21. Specification 808,531 is referred to.