Patent GB-813053-A (GB)
Title: Methods and apparatus for adjusting machines e.g. typewriters
IPC: B41J29/393
Filed: 1955-12-20
Abstract: 813,053. Automatic speed control. INTERNATIONAL BUSINESS MACHINES CORPORATION. Dec. 20, 1955 [Dec. 30, 1954], No. 36435/55. Class 38 (4). [Also in Groups XVI and XL (b)] To adjust a machine to obtain a predetermined performance factor, which is a function of a plurality of variables, a signal representing the difference between the value of said factor and the predetermined value is used to vary one of the variables in accordance with a predetermined decreasing progression so as continually to decrease the said difference. The embodiment described is a machine for automatically adjusting the impression mechanisms of an electrically actuatable typewriter so that the individual typebar speeds correspond to desired values coded on a punched card record. As shown in Figs. 1 and 2, a photo-cell unit 3 comprising two cells 1, 2 is interposed between the platen 4 of the typewriter and the type-bars such as 6. When one of the keys 5 is depressed the type-bar 6 is displaced past the cells 1, 2 by the power roll 7 and cam and link mechanism 8. The resulting pulse from cell 1 is fed to a binary counter unit 9 to open a gate 15 to pass 30 kc/s. pulses from a generator 16, while the pulse from cell 2 closes the gate, so that the type-bar speed is measured by the number of pulses fed through the gate 15 to the binary counter 17. The counter has a capacity of 127 and the 128th input pulse records a carry the presence or absence of which controls the unit 22 which determines the direction of rotation of the screwdriver in assembly 20 used to adjust the cam knock-off adjustment screw 21 associated with the tested type-bar. Two strokes of the type-bar are made for each adjustment the mean speed thereof being used to determine the setting, and each type-bar receives four adjustments in succession equivalent to two, one, onehalf and one-quarter turns of the screw 21. The type-key actuating member 30 is arranged to make a series of four double strokes and a final corrected single stroke. The desired speed for each type-bar is set up on a programme card 18 punched with a six bit binary code with one column for each type-bar. The number repiesented by the punched holes is the 128's complement of the desired number of 30 kc/s. pulses passed to the counter under the control of the cells 1, 2. Thus if, for example, the number representing the desired setting is 80, the counter is set to the 128's complement thereof, namely 48, and the presence or absence of a carry at the counter output determines which of the clutch magnets 23, 24 is energized. The appropriate clutch 25 or 26 is thus actuated to control the direction of rotation of a shaft 27, which drives the screwdriver 20 through gearing 28 and a flexible shaft 29. The cam knockoff screw adjustment assembly 20 and type-key depression assembly 30 are mounted on a supporting slide and circular rack to form a carriage assembly which is automatically displaced a predetermined amount across the typewriter keyboard, after performing a complete series of adjustments on one cam knock-off screw, so as to be in position to operate the next key and screw adjustment. Thus, commencing at the left side of the keyboard the adjustment device sequentially performs the testing and adjustment of each type-bar speed in turn, finishing on the right side of the keyboard. If an error occurs, due to a mechanical or counting defect, an error register 31 and indicating device 32 are operated to actuate the space bar of the typewriter between the last double stroke and the final single stroke and thus give a visual record thereof on the test sheet. On the completion of a single key adjustment cycle the typewriter carriage return key is operated by a cycle control unit 33 to reposition the typewriter carriage for the next strike up impression of the next type-bar. Simultaneously the assemblies 20 and 30 are advanced by an escapement mechanism 34 and the programme unit 10 is advanced to read the next column of programming. When a typewriter undergoing adjustment has been completed, a signal from unit 10 latches the type key actuating member 30 and actuates the adjustment carriage return mechanism to return the carriage to the left side ready to deal with the next typewriter placed in the apparatus. Full details of the mechanical construction and electrical circuits of the apparatus are described, Figs. 3 to 29 (not shown).