| 摘要 |
522,540. Keyboard switches OAK MANUFACTURING CO. Dec. 14, 1938, No. 36446. Convention date, Sept. 23, 1938. [Class 38 (v)] A set of plunger operated switches suitable for tuning radio receivers comprises a frame formed of channel members 10, 11 spaced apart by end members 13 which carry end plates 15 having lugs 35, 36 which'hold in position two insulating plates 27, 127 running the whole length of the assembly. The plates 27, 127 are formed with a series of apertures 41, 43 to accommodate sets of fixed spring clip contacts 46 according to the circuit arrangements required. The movable part of each switch comprises a plunger in the form of a plate 80 slidable in members 10, 11 by means of a shank 86 and lug 96, a spring 98 serving to bias the plunger to the outermost position. The plunger 80 is formed with lugs 81 which serve to carry insulating plates 60, 160 on which the movable contacts 63, 64 are carried. Each set of movable contacts is made from a blank as shown in Fig. 7, comprising a channel member having flanges 63, 64 for engagement with the sets of fixed-clip contacts. Apertures 67 are provided which facilitate the removal of parts of the blank to divide the contact into portions as shown in Fig. 1 to suit any desired switching arrangement. The loose mounting of plates 60. 160 on plunger 80 renders the arrangement self aligning. Also the distance between the edges 63, 64 and plates 27, 127 is less than the distance between the ends of the contact jaws 46 and the plates 60, 160. This ensures that the free movement is limited solely by the rigid contact edges 63, 64. The switches are operated by pressing knobs 87, a switch being held in the operated position by a nose 105 of a sliding spring-urged locking bar 100 engaging an aperture 90 in the plunger 80. Thus any switch is released by the subsequent actuation of another switch. An end plunger 181 may also operate an " on " and " off snapaction switch. |
