Patent GB-162928-A (GB)
Title: Improvements in ink ribbon mechanism for typewriting machines
IPC: B41J35/00
Filed: 1920-05-18
Abstract: 162,928. Fairweather, W. C., (Underwood Typewriter Co.). May 18, 1920. Ink-ribbon mechanism; ribbon - key actions. - In keyactions for adjusting the throw of the inkribbon vibrator and comprising a tumbler which co - operates with inclines on a rocking arm and is rocked from one incline to the other at each operation, a spring for rocking the tumbler is arranged so that the line of the pull moves from one side of the tumbler to the other at each operation; a special key may also be provided for silencing the vibrator for stencilling. The invention is shown applied to mechanism in which the lever 42 operating the vibrator 44 is provided with pins 50, 51 for engaging slots 40<a>, 41<a> respectively in a driving-member 39 connected by arms 49, 48 to a rock shaft 47; by rocking the shaft, the driving-member can be connected to the pin 50 or 51 to cause the presentation of the black or red strips 45, 46 of the ribbon, or the driving- member can be disconnected from the pins to silence the ribbon for stencilling. The rock shaft 47 is now provided with a cross arm 59 co-operating with a pin 57 on a tumbler or link 55 connected to the lever 53 of the ribbon-shift key 52. The tumbler is formed with a V guide-slot 63 for engaging a collar 61 on the rock shaft. A spring 67, Fig. 3, stretched between a pin on the tumbler and a finger 69 of the arm, passes between ears 70 on the finger. 'When the parts are, as shown, in the " black " position, and the key 52 is depressed, the pin 57 rides down an incline 58 on the arm 59 and engages a notch 60. Further depression of the key then rocks the arm and moves the parts into the " red " position, the movement being limited by the end of the slot 63 engaging the collar 61. The movement carries the spring 67 to the left of the tumbler, and on releasing the key, the tumbler and key lever are raised, the spring remaining at the left of the tumbler. On again depressing the key, the spring swings the tumbler slightly to the left and the pin rides down an incline 71 into engagement with a notch 72 and then rocks the arms and returns the parts to the normal or " black " position. The movements are limited by the engagement of the ends of the slot 63 with the collar 61, and by the engagement of a pin 76 on the arm with a slot 80<c> in a bracket 80. The parts are retained in the set position by the pin 76 engaging a hump 77 on a spring 73. The parts are moved into the " stencil " position, by means of a rocking key 78 pivoted at 79 to a bracket 80 and formed with inclines 82, 83 for engaging the pin 76. The stencil key is locked in the actuated position by means of a pivoted latch 86, urged upwards by a spring 87 having a shoulder 85, 88 for engaging a pin 84 on the key. If the parts are in the " stencil " position and the key 52 is depressed, the parts are restored to the " black " position, the spring 67 being effective to move the tumbler to the left and thereby cause the pin 57 to ride down the incline 71. The depression of the key 52 causes a pin 89<a> to engage the latch and release the stencil key. The shaft 47 carries an indicator 90 formed with black and red marks 92, 93 either of which is visible through an opening; when the parts are in the " stencil " position, equal portions of the marks are visible