GB1248444A - Memory backspace device for printing apparatus - Google Patents

Abstract

1,248,444. Typewriters. INTERNATIONAL BUSINESS MACHINES CORP. 3 Oct., 1968 [15 Nov., 1967], No. 47030/68. Heading B6F. Backspacing; width unit counting.-A memory backspace device for a typewriter includes a latch 50 biased towards its activated position in which it can retain a backspace key lever 26 in its fully depressed position for automatic repeat backspace operations, and a control means coupled to the latch 50 by a cable 52, which control means deactivates the latch 50 to release the backspace key lever after a selected amount of backspacing has occurred. The backspacing key lever 26 is depressible by two amounts, the initial amount giving single backspacing, and the full amount, in which position it may be latched, giving repeat backspacing. The control device, Fig. 1, includes a memory bracket (11) having a memory lever 12 universally mounted thereon by pins 21 and 22. The lever 12 has a friction pad 14 for engaging the bottom of a movable member 10 attached, for example, to the platen of the typewriter. A spring 23 biases the lever 26 upwardly and to the left so that it engages a stop 17 and the friction pad 14 engages the movable member 10. In this position the latch 50 is held in its non-retaining position by the cable 52. Movement of the platen and therefore the movable member 10 due to a typing operation, results in movement of the memory lever 12 away from the stop 17, and activation of the latch 50. Movement of the memory lever will be a direct measurement of the width units allotted to a character or a word, depending on the type of typewriter. A cable 58, when operated, pivots the lever 12 about pin 22, thereby moving pad 14 away from the movable member 10 to allow the lever 12 to return to stop 17. If the memory backspace device is to be utilized on a proportional spacing typewriter, the cable 58 is connected to a portion of the typewriter actuated during each actuation of a character key, e.g. the ribbon lift mechanism. If the selective amount of movement of the memory lever is the typed word, the cable 58 is connected to an interword function mechanism, e.g., the space bar mechanism of the typewriter. A cable 62 which operates in a similar manner to cable 58, is connected to means responsive to the various function operations, e.g., the carriage return or tabulation levers. In an alternative embodiment (Fig. 4), a latch (89) similar to the latch 50, Fig. 1, is provided for the backspacing key lever 26. However, the control means includes a wheel 70 spring biased into contact with the movable member 10. Mounted on the axle of the wheel (70) is a pulley (78) for driving an endless band (79) spring biased to a reference position at which the latch (89) is deactivated. The axle of the wheel (70) has one end journalled in one arm of a bell crank lever, the other arm of which is connected to a control link 77. This link 77 is actuated to tilt the bell crank lever and move the wheel (70) away from the movable member by cables connected to similar parts of the typewriter as cables 58 and 62 of Fig. 1.