Patent GB-1099396-A (GB)
Title: Improvements relating to character recording apparatus
Filed: 1965-11-03
Abstract: 1,099,396. Selective printing. INTERNATIONAL BUSINESS MACHINES CORPORATION. Nov. 3, 1965 [Nov. 5, 1964], No. 46496/65. Heading B6F. [Also in Division G4] Type-carriage letter-spacing; carriage-return; margin stops.-A wire-printer type-head 15 is driven, step-by-step, by a reversible drive along a recording line and when it reaches the righthand margin it is returned to the left where it overshoots the margin and whereat overshoot sensing means, actuated by the presence of the type-head, causes forward drive of the head to the commencement of a new line. The type-carriage is attached to a steel tape 30 guided round pulleys 31, 32 and a drive pulley 33 driven by a print head drive motor 35. On shaft 37 of the motor is a feedback emitter consisting of a slotted disc 36 coacting with a light and photo-cell unit 38 to provide signals to a print head and carriage control unit 26. The control unit 26 is electrically connected with a print control unit 17 having an emitter 22 on a shaft 21 driven by a motor 20. A pickup element produces timed output signals to control the movement of the type-head by operation of motor 35. The disc 36 is so positioned on the motor shaft 37 that as soon as the print head 15 approaches the next position a pulse is transmitted to effect a timed reverse energization of the motor 35 to stop it. At the right-hand end of the carriage travel, a switch 41 is closed, and on the return of the carriage to the left three switches in a unit 40 are closed. The first switch to close is a Margin Sense contact 40a then at one letter-space further to the left, a Return Stop Sense 40b, and finally at a three letter-spaces an Interlock contact 40c. When the print head effects closing of the right-hand margin contact it operates electronic circuits to effect a reverse operation of the print head motor 35. Upon reaching the left-hand margin the first contact is closed and then the Return Stop Sense switch 40b. This resets circuits and effects energization of the motor in the forward direction after a 150 microsecond delay. Forward direction is controlled with the print head incrementing until it leaves the switch 40b so that the print head returns to the first print position in the required two or three letter-space stops. Character selection.-Data bits received over lines 26a, Figs. 4a-4e (not shown), from a central processing unit are stored in latches of a register 80 and are used to control the set up of the wires 14 by being selectively applied to windings 89a-89n of reed switches for providing circuits to windings 58 releasing latches 45, Fig. 2 (not shown), for operation of the print wires. The latches 45 are also controlled by a doublelobed cam 70a, 70b. At the time of being released by the armatures 52 of electromagnets 58, the latches may pivot counterclockwise. This permits an interposer 62 to move, under the influence of spring 67, above the end 45a of the cam is adjacent end 45a, the presence of end 62b of interposer causes a vertical movement of a print slug 42. A wire 14 is accordingly moved to effect printing. A shoe 65a withdraws the interposer 62 and a lever 72 restores the print slug by means of fork 72b and cam 70. Error correcting.-In order to check the validity of a character in the register (80), an oiled bit parity check circuit (180) is provided for operating a character check latch 182 wherever a wrong character exists. A check stop switch (173) and an inverter (174) provide a signal through OR circuit (183) for disregarding the check circuit (180) if desired.