Patent GB-616522-A (GB)
Title: Improvements in or relating to scanning devices for use in pulse reflecting systems
IPC: H01Q3/10
Filed: 1944-02-15
Abstract: 616,522. Toothed gearing; converting rotary into oscillatory motion. SPERRY GYROSCOPE CO., Inc. Feb. 15, 1944, No. 2826. Convention date, April 10, 1942. [Class 80 (i)] [Also in Group XL (c)] In a radio beam scanning device, a radiator or reflector has a rotary motion which may be combined with an oscillatory or nodding motion about an axis approximately perpendicular to the direction of the beam and to the axis of rotary motion. The parabolic reflector 1 is carried by a yoke 7 integral with a casing provided with a sleeve 9 driven from a gearwheel 17 on a main driving shaft 13. A gear 19 on the same shaft drives a sleeve 25 integral with a disc 27 having a cam groove 29 engaged by a follower 31 which actuates a rack 33 in a direction at right angles to the plane of the paper. The movement of the rack 33 rotates gearing 35, 41, 43 to produce oscillation of the reflector about the axis 3. The nodding motion is interrupted by the operation of a solenoid 77 which moves sleeve 91 downwardly and rotates a pivoted lever 95 which urges a shaft 37 to the left, disconnecting gear 41 from gear 35 and permitting a latch member 71 to move vertically and bring a roller 65 into engagement with a recessed cam 59 normally oscillated with the reflector. The oscillatory motion is resumed by the release of solenoid 77<1> allowing shaft 37 to move to the right and when the roller 65 and latch 71 have been moved downwardly by cam 59 the enlarged head 73 springs into the recess and holds the latch 71 in its retracted position. In a modification, Fig. 4 (not shown), the sleeve 91 is formed with a projection which is moved by the electromagnet into the path of a notched cam disc mounted beneath the reflector and the gearwheel effecting the reciprocatory motion is simultaneously disconnected from its driving sleeve. A further modification in which the oscillating movement is effected by a link connected to a follower engaging a helical cam groove is described in connection with Fig. 6 (not shown). In a further arrangement, Fig. 8, the yoke 7 is rotated from gears 21, 17 and a gear 19 on the main shaft 13 drive a gear 23 to which is keyed an elliptical gear 137 meshing with a second elliptical gear 139. The gear 145 driven at a variable rate from the elliptical gear 139 is connected to an internally-toothed gear 149 and idler 'gears 133 are mounted on pins 135 secured to a carrier 131 rotated at a constant speed. The average speed of the toothed gear 149 is arranged to be equal to that of the carrier 131 and the bevel gear 153 is periodically reversed and meshes with a helical gear 155 by which reflector 1 is oscillated about the axis 3. The oscillatory movement is interrupted by the operation of solenoid 77<1> which through a collar 157 slides gear 153 out of its driving position and at the same time lowers disc 161 provided with a tooth 159 which engages a recess in the gear 155 to stop the reflector in the appropriate position for conical scanning. In a further modification, Fig. 9 (not shown), and generally similar to Fig. 8, the oscillatory motion is derived from a differential gear of which one member is driven from the main shaft and a second member is oscillated by an independently driven crankshaft so that a third member driven at a constantly varying speed and meshing with gears carried by the constantly driven yoke produces an oscillatory movement of the reflector member. Suitable joints for the wave-guide 47, 51, 53, 57, Fig. 1, are described in Specification 579,763, [Group XL].