GB1274076A - Oscillatory scanning device - Google Patents

Abstract

1,274,076. Oscillating motors. HUGHES AIRCRAFT CO. 16 Sept., 1969 [11 Oct. 1968], No. 45609/69. Heading H2A. In a scanning device a pivotally mounted element, such as a mirror 16, is oscillated through a predetermined angle by an electromagnetic driving arrangement energized over pairs of contacts closed by the element at the ends of its travel, means being provided for bearing the element to one of the ends of travel. In the embodiment shown in Figs. 6, 8, and 9, the mirrror is pivotally mounted in a frame at one side by means of a shaft 18 engaging a bearing- 20 in a stationary core 60 and at the other -side by cruciform spring blades 32, 34. Core 60 is surrounded by a coil 64 and both are located in a housing 22 having internal teeth 70, Fig. 8, cooperating with teeth 76 on an annular rotor 74 secured to the mirror. Also secured to the mirror is a contact element 44, Fig. 9, having spring arms 50 carrying contacts 54 which cooperate with fixed contacts 52 at the limits of travel of the mirror, these pairs of contacts being connected in the circuit of coil 64. Fig. 8 shows the position of the teeth when the mirror is in the centre of its travel, and when the device is inoperative, the cruciform spring mounting blades 32, 34 bias the mirror to one limit of its travel where the teeth 70, 76 are out of register and one set of contacts 52, 54 is closed. Thus, on energisation of coil 64 over these contacts a torque is applied to rotor 74. Immediately the rotor moves, the said contacts 52, 54 open and the other pair are closed as the mirror reaches its other limit of travel. Torque in the opposite direction is then applied to the rotor and the energy stored in spring arm 50 by the momentum of the mirror supplements this torque in returning the mirror to its starting point where-upon the cycle repeats. 'The shaft 18 may be omitted and the rotor 74 provided with a bearing engaged by a fixed pin which locates the core 60 centrally, Fig. 10 (not shown). In a further modification, Fig. 12, spring mounting blades 33, 34 are replaced by a pivot comprising a shaft 90 on the mirror which is attached to a toothed rotor 94 mounted on a bearing 96. A shaft 98 suppots. bearing 96 and is surrounded by a, permanent magnet 102 in a housing 100 having teeth 104 cooperating with the rotor 108. The spacing of teeth 104 is greater than the width of teeth 108 so that in the intermediate position of the mirror, in which teeth 100 lie midway between teeth 104, the permanent magnet exerts a torque on the rotor 94 biasing it to-either of the limit positions of the mirror in which teeth 104, 108 are in alignment.