Patent GB-265136-A (GB)
Title: An improved keyboard for calculating machines
IPC: G06C7/06
Filed: 1926-04-26
Abstract: 265,136. Burroughs Adding Machine Co., (Assignees of Horton, A. A.). Jan. 29, 1926, [Convention date]. Adding-apparatus; keyboards; interlocking. - In a multiple bank machine such as described 'in Specification 265,122, the keyboard is formed as a self-contained unit that may be readily attached to and detached from the machine and is provided with improved means for restoring the depressed keys and for controlling certain of the operating parts of the machine such as the zero stops and actuating means. As shown in Figs. 1 to 4, the keyboard frame consists of banks of amount keys 10 and a bank of control keys comprising error, repeat, non-add, total, and subtotal keys extending through slots in a top plate 20 and bottom plate 21 spaced apart by three upright plates 22 and secured to the top plate by screws 30, Fig. 9, engaging nuts mounted in openings in the spacing plates. The spacing plates have downwardly projecting front portions 32 acting as bearings for a shaft 34 and similar projections at the rear have holes for screws 35 to secure the frame to the machine. Each amount key has a flat stem plate 40 with two long and short slots 41, 42 whilst the stems 46 of the control keys have single upper and lower slots 47. The keys are guided by plates 43 passing through the right hand slots 41, Fig. 4, the plates 43 having projections 45 bearing on the top plate 20 and connected by a rod 44. The lower ends of the amount key stems are shaped to co-operate with the usual off-set projections on the differentially movable members 233 and each stem is perforated at 70 to receive a coiled spring 71 passing through all the perforations and through the eyes pressed out from the bottom plate ard secured to rods at its ends. A spring-controlled latch plate 50 with projections 55 passes through the left hand slot 41 of each bank of keys to hold the depressed key in position and is connected at its forward end to a corresponding zero-stop member 62 pivotally mounted on the shaft 34. Each zero stop member has a rearward extension 63 adapted to cooperate with the differential member 233 to prevent movement thereof when no key is depressed in the corresponding bank and is provided with a bifurcated portion 64 co-operating with a control shaft 65 supported by links 66 pivoted to the shaft 34. Rearward movement of the shaft 65 is permitted during the forward stroke of the main handle 70 by imparting a movement to a spring- controlled sliding member 201 guided in slotted plates 202 and limited as to movement by a pin 203 and projection 206. When the shaft 65 is in its rear position those stop members in the banks in which no key is depressed are moved to such an extent that the extensions 63 align with the ends of the corresponding differential members 233 whereas in those banks in which a key is, depressed movement of the top members is arrested since the latch projections 55 engage the depressed key stems. If a key is only partially depressed the latch member cannot move forwardly so that the corresponding zero stop member blocks the movement of the shaft 65 on an operation of the main handle and by means of an arm 193 automatically disconnects the actuating mechanism of the machine. The sliding member 201 in addition to its longitudinal movement can tilt about the pin 203 so that a roller 209 on the shaft 65 can engage the outer of two shoulders 207, 208 on the slide 201 and during the return stroke of the handle this shoulder forces the shaft 65 beyond its normal position to ensure release of the keys. At the end of the return movement the slide is rocked counter-clockwise to restore the parts to normal the roller 209 engaging then the shoulder 207. The control key bank is provided with " crowding look " plates 80, Fig. 7, to prevent the locking down of more than one key and the restoring of a depressed key when a second one other than the error key is depressed. When the error key E is depressed an arm 84 on the latch plate 50 of the control bank is effective to move the latch plate 50 beyond its normal position to cause the shaft 65 to move sufficiently to release all the depressed amount keys. An interlock between the amount keys and total and sub-total keys is provided to prevent depression of the amount keys during total taking operations and comprises a spring controlled transverse slide 90 with notches 92 normally opposite the extensions 55 of the latcn plates and depending portions 93 with inwardly extended ears 94, 95 for co-operation with inclined recesses in the total and sub-total key stems.