Patent GB-587422-A (GB)
Title: Improvements in typewriters
IPC: B41J23/16
Filed: 1944-11-02
Abstract: 587,422. Typewriters. STEVENS, A. H. (Smith & Corona Typewriters, Inc., L.C.). Nov. 2, 1944, No. 21477. [Class 100 (iv)] In a typewriter, the case-changing movements of a type-bar segment 13 or the similar movements of any other operation-effecting element of the machine, are obtained by the key control of power-actuated mechanism through a rack 47 reciprocated to and from a normal (i.e., lower-case printing) position and a mutilated pinion 66, the pinion being rotated through one revolution at each depression of the key 103a to operate the rack and is disengaged from the rack at the end of the revolution. The type-bar segment 13, which is slidable on bearings 18, and pivoted to links on a shaft 20, is locked in its raised or lowercase position, Fig. 2, by a toggle mechanism 27, 28, the free end of the link 28 being pivoted by a pin 26 to a plate.24 adjustably secured to the shaft 20. Movement of the toggle in locking direction is limited by a lug 32 on the link 27 engaging a stop 33 on the lever 28. A link 35 slotted at 36 to slide on the pin 26 has a camsurface 34 which, during the power-actuated forward movement of the link engages the pivot 29 of the links, 27, 28 and breaks the toggle so that the segment 13 drops under gravity into the position for upper-case printing. An adjustable stop 90 on a rod 88 screwed into the segment limits such movement, and the engagement of the head of the rod with the fixed frame 10 limits the reverse movement. When the link 35 is allowed to move backward under the action of an adjustable spring 43, the end of the slot 36 engages the pin 26 and rocks the plate 24 to restore the segment to its normal or lower-case printing position. The rear end of the link 35 is pivoted at 37 to one arm 38 of a three-armed lever 38, 40, 41 pivoting about a shaft 42. A toothed sector 47 pivoted to the frame 10 has a pin-and-slot connection 65 with the arm 41 and gears with the mutilated pinion 66 which is also free on the shaft 42. The parts 35, 38, 40, 41 are locked in the upper-case printing position by togglelevers 51, 53 the upper lever 51 being adjustably pivoted at 52 to the frame 10 and the lower lever 53 being pivoted at 55 to the end of the arm 40. Its locking movement is limited by the engagement of stops 57, 58. The movement of the parts 35, 38, 40, 41, 47 under the action of the spring 43 is limited by the engagement of the pin 65 with a stop 93. The shaft 42 is driven continuously by an electric motor, and the pinion 66 is coupled to it for one revolution when upper-case printing is required, by a clutch device consisting of a pawl 69 pivoted on an arm 67 fixed to the pinion 66 and caused by a spring 71 to engage teeth on a disc 68 fixed to the shaft 42. At the end of one revolution, projecting lugs 69a, 67a on the parts 69, 67 are engaged in that order by a lug 79 on arm 72 of a three-armed lever 72, 73, 74, the pawl 69 thus being retracted and the pinion 66 stopped. A spring catch 80 on the arm 72 slips behind the lugs 67a, 69a to prevent retrograde movement. At this point, the sector 47 has been moved to its lower position to operate the link 35, and the mutilated part of the pinion is opposite thereto, so that when the locking action of the toggle 51, 53, is released as described below, the spring 43 moves the parts 35, 38, 40, 41 and 47 back to their initial position and restores the segment 13. To set the devices in operation, one of two independent shift keys 103a is depressed and acts on a pin 121 carried by a spring-controlled lever 123, and the pin 121 acts on an extension of a lever 102a pivoted to a bar 110 to move the bar rearwardly. A shoulder 112 on the bar engages a toe 74a on the arm 74. to move the lug 79 on the arm 72 away from the lugs 67a 69a.so as to allow the clutch to engage and rotate the pinion 66 one revolution. A bar 114 pivoted at 55 to the arm 40 is moved downwardly during this revolution so that a foot 114a thereon engages a notch 113 in the bar 110. During the return movement of the bar 110 after release of the key 103a the bar 114 is rotated clockwise about its pivot 55 and a projection 114b at the upper end thereof engages the hinge 54 of the toggle 51, 53 to break it, thus allowing the spring 43 to operate and restore the parts. At the same time, the arm 72 can move into position under the action of a spring 78 connecting it to the bar 110, to throw-out the clutch. To allow the apparatus to be set in upper-case printing position for as long as is required without repeated depression of the keys 103a, a shift-lock key 104a is provided. When the key is operated, a projection 126 thereon engages the'lever 102a to cause case-shift. A latch 127a connected by a spring to the lever 123, holds the key 104a depressed for as long as is required. The key 104a is released if one of the keys 103a is depressed, when the pin 121 engages the latch 127a and releases it, thus allowing the key 104a to rise under spring action to its normal position. In order to prevent premature return of the bar 110 should a key 103a be struck a momentary blow, a safety-catch 136 is hinged to the bar 110, and engages behind a guide 77 when the bar 110 moves rearwardly to prevent its immediate return. The downward movement of the bar 114 during the revolution of the pinion 66 moves the bar 110 downwardly against the action of spring 78 so as to carry the catch 136 below the guide 77 thus enabling the bar 110 to return to normal position.