Patent GB-627692-A (GB)
Title: A mechanism for automatic adjustment, to preselected settings of movable elements such as tunable components in radio and like electrical circuits
IPC: H03J5/20
Filed: 1945-10-18
Abstract: 627,692. Stopping in predetermined positions. HARRISON, R. Oct. 18, 1945, No. 27306. [Class 80 (ii)] [Also in Group XXXVIII] In apparatus of the kind claimed and described in Specification 612,315, for the automatic adjustment of a movable element to one of a number of preselected settings such as in tuning a radio receiver, a motor A, Fig. 1, drives a shaft D which drives shafts S and G through respective worm gearing and oppositely arranged free-wheels. Shaft S carries a number of discs, each having a notch in its periphery adapted to receive the spring- urged head of its associated latch arm L pivoted about O, arranged so that the notches are evenly spaced about the shaft. Shaft G drives the adjustable element and is geared to shaft H so that the latter runs slightly faster, and both shafts carry notched discs equal in number to those carried by shaft S, and rotatable about the shafts to define the various settings of the adjustable member which are available for preselection. The ends of the latch bars are connected to T-shaped links I, which are slidable to engage the notches in corresponding discs on shafts G and H. Shaft S drives a rotary switch SD, Fig. 2, having contacts equal in number to the notched discs in the shaft, and spaced equally around the periphery, connection being made to all contacts except the one selected by the switch member. The shaft also drives a disc SGD with notches corresponding to the switch positions, and operating a springset B. The desired position of the driven element is selected by the multiple contact switch RC which is placed for example on position PN2. Relay COR is energized through switch SD, and motor A rotates in the forward direction to rotate shaft S (but not shafts G and H) until it reaches the position corresponding to -the selected position PN2 of the driven element. The relay-circuit is then disconnected by switch SD; but is continued through spring-set B until exact correspondence causes notched disc SGD to open the contacts and release the relay. The motor now reverses, rotating shafts G and H (but not shaft S) until the shaft G reaches the preselected position, when the notches on the appropriate pair of discs are positioned to allow engagement of the associated T-link I, while the notch on the appropriate disc of shaft S is also positioned correctly so as to receive the head of the associated latch-bar L, allowing the T-link to descend into position to lock the shafts G and H, and to break the motor circuit by opening contacts F. On repositioning the control switch RC, shaft S again rotates, the head of latch bar L rides out of the notch on to the disc periphery, shafts G and H are freed, and the mechanism operates as above. In modifications (not shown) an additional channel of selection may be provided for manual operation of shaft G, a plurality of variable components may be controlled by one mechanism, or a second shaft may be controlled in turn by the motion of the main controlled shaft.