Patent GB-139796-A (GB)
Title: Improvements in ink ribbon mechanism for typewriters
IPC: B41J33/516
Filed: 1920-03-03
Abstract: 139,796. Akt.-Ges. vorm. Seidel & Naumann. Nov. 15, 1918, [Convention date]. Void (Published under Sect. 91 of the Act]. Ink-ribbon mechanism.-In automatic feed reversal mechanism comprising a driving-shaft 1 which is shifted longitudinally to transfer the drive from one spool 21 to the other spool 20, the shifting-devices comprise a spring-urged member which is released and re-set periodcially. In the mechanism shown, the shaft 1 is provided with pinions 8, 9 adapted to engage pinions 10, 11 on cross shafts 12, 13 which are geared to the spool shafts 18, 19. The spring-urged member consists of a three-armed lever 23 which is pivoted at 23e to a bracket 22, and is connected to a spring 28. The bevelled arm 23<a> of the lever 23 engages a pin 25 on a lever 24 which is pivoted at 24a to the bracket and is provided with a pin 26, engaging a collar 27 on the shaft 1 The lever 24 is connected to a spring 29. The arm 23b of the lever 23 is formed with steps a - - d for co-operating with a lever 30 which engages a lever 32 carrying a guide-pin 33 for the ink-ribbon 34. When the spool 21 is the winding-spool, the parts are in the positions shown, the lever 30 resting on the step a. and the bottom bevel of the arm 23<a> engaging the pin 25. When the spool 21 is empty, the increased tension of the ink-ribbon causes the lever 32 to rock the lever 30, and the lever 23 is released and is rocked by the spring 29, the movement being limited by engagement of the step b with the lever 30. During the movement of the lever 23, the arm 23<a> rocks the lever 24, and the shaft 1 is shifted, the device being transferred to the spool 20. At the end of the movement, the pin 25 abuts on the end of the arm 23<a>. When the spool 21 is empty, the increased tension of the ink-ribbon again causes the lever 30 to be rocked, and the lever 23 is rocked by the spring 29 until the step c engaes the lever 30. During this movement, the spring 29 returns the lever 24, the pin 25 riding on the top bevel of the arm 23<a>, and the drive is transferred to the spool 21. The parts are re-set in the position shown by the following device, which is operated automatically during the return of the platen carriage. Dogs 36, 37 are pivoted on the arm 23<c> of the lever 23, the dog 36 being held by a spring 38 in contact with a pin 39 on the dog 37. The dog 36 is normally out of the path of one or more tappets 41 on the carriage rack 40, but when the lever 23 has been rocked until the step c engages the lever 30, the dog 36 is raised by engaging a pin 46 on the bracket 22, and the dog 37 is raised into the path of the tappets. When the carriage is returned, the tappet engages the dog 37, and the tail 36<a> of the dog 36 engages a lug 23d on the arm 23<c> and causes the lever 23 to be rocked. The lever 30 then rides in contact with a guide 23f and is returned to the normal position by a spring 35. In the return movement of the lever 23, the shaft 1 is momentarily shifted to the left by the lever 24. To prevent the shaft from being obstructed by the engagement of the teeth of the wheels 8, 10, the collar 27 is mounted to slide on the shaft and abuts on a spring 42. The stepped lever 23 may be replaced by an anchor mechanism or the like, The mechanism can be operated by turning the spools manually. When the lever 23 has been rocked to bring the step c into engagement with the lever 30, the shaft 1 can be set in the neutral position, in which neither of the shafts 12, 13 is in gear, by permitting the step d to engage the lever 30, the arm 23a thereupon engaging the pin 26 and causing the lever 24 to shift the shaft.