Patent GB-1048275-A (GB)
Title: Improvements in or relating to keyboard mechanism for an electric writing machine
IPC: B41J25/00
Filed: 1963-07-15
Abstract: 1,048,275. Typewriters. ROYAL McBEE CORPORATION. July 15, 1963 [July 16, 1962], No. 27978/63. Heading B6F. In a power-driven typewriter comprising, for example as described in Specification 842,327 a settable printing-head carrying all the characters, each key-lever 17, Fig. 4, operates to select a type through an interposer 22 movable horizontally and vertically by a drive shaft 31, and depression of a key-lever causes downward movement of the interposer to effect a cyclic rotation of the shaft 31. Type-selectors; interlocks.-Each key-lever 17, Fig. 4, is pivoted at 18 and carries a conventional by-pass arm 26, the bottom of which engages and depresses an interposer 22 when the key is actuated. The interposer is slotted at 22a to engage a fixed pivot 23 and is urged rightwardly by a spring 24. At its other end, it has an aperture 22d engaging a fixed pin 25 limiting its vertical movements, and a blade 22e which in the lower position of the interposer is in a position to actuate one or more of permutation bails 29 when the interposer is moved to the left and select a type face to be printed. On the lower edge of the interposer is a blade 22k and a laterally projecting finger 22n. When an interposer is depressed, the blade 22k enters a ball-lock 34 to prevent depression of any other key and the finger 22n is engaged by a spring-urged latch 37, the nose 37d of which normally abuts against the finger 22n as shown. Pivotal movement of the latch 37 depresses a bar 40 which, through a linkage 50... 55, Fig. 3A, releases a pivoted stop 48 from a stop 47a on a cam member 47 forming part of a wrap-spring clutch mounted on a constantlyrotating shaft 44. The shaft 44 rotates the cam 47 and, through the clutch, drives a shaft 31, Fig. 4, until the stops 47a, 48 re-engage to uncouple the clutch. Two arms 32, 33 are provided on the shaft 31. During a revolution of the shaft 31, firstly the arm 32 engages an abutment 22j on the interposer to move it leftwardly to set the bails 29, and secondly the arm 33 engages a surface 22f on the interposer to move the latter upwardly and so free the ball lock. The restoration of the operated interposer takes place during an initial part of the printing cycle so that if a second key is depressed before the cycle is completed, its interposer is latched as already described and, through the bar 40, maintains the stop 48 in disengaged position so that rotation of shaft 31 continues and arms 32, 33 in due course cause operation of the second interposer and selection of the corresponding type face. Space-bar actions.-Actuation of a space-bar 12, Fig. 2A, causes a spring-raised interposer 65 to be moved downwardly about its pivot 23 through the intermediary of a conventional by-pass lever 63. The interposer 65 has a blade 65b for engagement with the ball-lock 34, and a stop 65a (see also Fig. 2) which in the rest position of the interposer engages one or other of two stop arms 70b, 70c on a member 70a forming part of a wrap-spring clutch-device mounted on a continuously-rotating shaft 73. The member 70a is integral with a member 70e which has circumferential cam surfaces 70j, 70k terminated by abutments 70f, 70g. A finger 90c is positioned in the path of one or other of these abutments if a type-key interposer 22 is in latched position, the finger being carried by a bail 90 operated by a bell-crank lever 93 connected to the bar 40 which, as already described, is moved downwardly by a latched interposer 22. The other part of the clutch is a member 71a also rotatably mounted on the shaft 73, the wrap-around spring extending between members 70c, 71a. The member 71a has lobes 71b, 71c which can act on a lever 81 which, when operated, actuates the escapement through a link 84 and moves the by-pass lever 63 to inoperative positions through a link 85 and pin-and-slot connection 63a. If no type action has been set, finger 90c is inoperative, depression of space-key 12 withdraws stop 65a from engagement with arm 70b or 70c. The clutch now becomes operative and parts 70a, 70e and 71a rotate with the shaft 73. The lever 81 is thus actuated so that the escapement is operated and interposer 63 moved to inoperative position, the latter causing the stop 65a to be restored to operative position. If, however, a printing cycle is till in operation when the space key is depressed, the finger 90c is in operative position. In this event, withdrawal of stop 65a causes clutch engagement to start members 70a, 70e, 71a rotating, but such rotation is stopped after 3 degrees of such rotation by finger 90c engaging an abutment 70f or 70g. Member 70a has moved sufficiently, however, for arm 70b or 70c to overlie the stop 65a, so that as soon as the arm 40 rises during the completion of the printing cycle and releases the finger 90c, the clutch becomes operative to carry out a spacing operation. If a keylever 17 is depressed during a spacing operation, its interposer 22 is latched but shaft 31 is not operated until the bar 40 is allowed to move sufficiently downwardly by the action of a cam surface 70j or 70k on the finger 90c.