Patent GB-776409-A (GB)
Title: Printing unit, especially for record controlled business machines
Filed: 1955-05-26
Abstract: 776,409. Record controlled printing. INTERNATIONAL BUSINESS MACHINES CORPORATION. May 26, 1955 [May 29, 1954], No. 15199/55. Class 100(4) In a printing unit for a record controlled machine, having a series of type wheels set by stepping wheels mounted on a drive shaft, a resilient coupling is provided between the drive and the stepping wheel. The type wheels 1, Fig. 2, are mounted on levers 2 biased by spring 3 to make an impression on a platen 4. Each of the type wheels 1 is set, through an idler wheel 12, by a stepping wheel 8 actuated by a drive wheel 6 mounted on one of three drive shafts 5 and coupled to its wheel by a pretensioned spring 7, the relative movement being limited by stops 9, 10. The setting of a type wheel is controlled by a double pawl 22 normally held clear of the step-- ping wheel by the 'armature 27 of an electro-magnet 26. Sensing of a digit hole energizes the electro-magnet 26 releasing the pawl 22 which engages and stops the stepping wheel 8, as shown, the drive wheel 6 continuing to tension the spring 7. This positions a digit type but if a zone hole is sensed an electro-magnet 34 is actuated and on each occasion rocks the pawl 22 allowing the spring 7 to advance the wheel 8 another step thus positioning the appropriate alphabetic or other type. Printing is now effected by movement of a set up bar 13 which allows a locking lever 14 to move to lock the type wheel by a tooth 14a entering a recess and to move 'an interposer 17 into the path of a releasing slide 18 which, acting through the interposer, depresses a stop lever 19 to allow the lever 2 to effect impression by its spring 3. Slides 40 are provided controlling and interlocking the stop levers 19 in such a way that, in position I zero will be printed to the right of the significant figure, in position II zero will be printed on both sides of the significant figure, and in position III the type wheel is inoperative. Restoring slides 36 to 39 are provided for the various parts. Fig. 7 shows a modified pawl arrangement 52, 53 for controlling the stepping wheel 8 by a single electro-magnet 50 which upon its first energization forces the pawl 53 through an arm 56 to stop the wheel 8 and unlocks the pawl 52 from an arm 59; the pawl 52 however is held by an off set 57 until deenergizing of the electro-magnet 50 when as the pawl 53 withdraws it is released to engage the wheel 8 before the pin 58 is re-hooked by an arm 59. This positions the type wheel for a digit but if zone holes are sensed the electro-magnet 50 is again energized this time closing the contact 62 so that a number of pulses to the magnet 50 then rock the pawls 52, 53 to give additional steps to the type wheel. Fig. 10 shows another modification of the pawls 71, 72 for use with a modified type wheel which after positioning a digit type steps back the wheel 8 and hence the type Wheel. The first energization of the electro-magnet 77 causes the pawl 71 to stop the wheel 8 and the second pawl 72 to become engaged in a second notch 79 in the armature 78. A second energization, by a zone hole releases the pawl 72 to engage a bail 75 which is then moved by a cam drive on receiving zone pulses to back step the wheel 8 the required amount. This arrangement can be adapted for use with a three hole code when additional characters are required by employing a second zone hole.