Bulb socket

A lamp-holder having a substantially cylindrical outer housing (1) provided at one end with an aperture (2) and preferably with means for fixing a two-wire electric conductor (3) introduced into the aperture and being open at the opposite end to permit introduction of a bulb, and a yoke (4) provided within the housing (1) and movable to a limited extent and having, somewhat inside the open end of the housing, a female thread (5) corresponding to the male thread of the bulb base, characterized in that, at some distance from and inside the inner end of the female thread, the yoke (4) is provided with an outer plate (15) which is axially movable with respect to the yoke and has a pair of contacts (19) protruding slightly from the inner face thereof, said contacts being each conductively connected with a resilient contact element (20, 21) projecting from the outer face of the plate and adapted, upon the bulb being screwed in, to engage corresponding conductive elements on the bulb, a pair of yoke legs (4a, 4b) which extend inwardly from the portion of the yoke provided with the thread into the housing to some distance outside the inner end of the housing being interconnected adjacent the inner ends thereof by an inner plate (9) which is immovable with respect to the rest of the yoke and has a pair of conductive lead-through elements (13) for receiving and fixing the two conductive wires of the conductor the portions of which that are located within the housing carrying the inner plate and hence the yoke and each being provided with a contact (12) opposite the contacts of the outer plate, said inner plate carrying on the outer face thereof a compression spring (14) in its turn carrying the outer plate which, upon a bulb being screwed into the thread, via one of the resilient contact elements (20) and against the action of the spring is pressed inwardly in the direction towards the inner plate until the outer plate, in a position in which its contacts (19) have not yet engaged the contacts of the inner plate, is arrested by a stop (7a) on the housing against continued inward motion, and, upon continued screwing in of the bulb, on account of the fact that now the outer plate is immovable with respect to the housing, the yoke being caused to move outwardly with its with respect thereto immovable inner plate and its contacts until the contacts of the inner plate engage the contacts of the outer plate and the yoke engages a stop (7b) on the housing against continued outward motion, the said movements being executable in the reversed order.