A theftproof lamp (100), including a lamp body (110) and a lamp cap (120). A spring member (140) and a ratchet wheel mechanism (130) are provided inside the lamp for cooperating with each other and enabling theftproof effect. When turning the lamp clockwise, the lamp can be screwed down to a lamp socket. When turning the lamp counter-clockwise, the lamp can only make repetitive circular motions around the ratchet wheel and therefore achieve the theftproof effect. When a user needs to remove the lamp in a safe way, a bolt (170) can be moved inwardly to block the spring member from moving upward, so that the lamp body, ratchet wheel and lamp cap form a whole, without any movement in relation to each other, and therefore allowing easy removal of the lamp.

The invention provides a lamp screw cap (200) comprising a thread structure (220), wherein the thread structure (220) comprises repetitive elements (225) defining tops (230), valleys (240), and a central plane (250), wherein tops (230) protrude relative to the central plane (250) and wherein the valleys (240) are recessed relative to the central plane (250), wherein: for a plurality of tops (230) applies that each top (230) comprises a first top segment (231), a second top segment (232), and a middle top segment (233), together defining the top (230), wherein the middle top segment (233) is configured most remote from the central plane (250); for a plurality of valleys (240) applies that each valley (240) comprises a first valley segment (241), a second valley segment (242), and a middle valley segment (243), together defining the valley (240), wherein the middle valley segment (243) is configured most remote from the central plane (250); the first top segment (231), the second top segment (232), the first valley segment (241), and the second valley segment (242), have the same first curvature; one or more of the following applies: the plurality of tops (230) have a protruding part (235) protruding relative to the first curvature in a direction away from the central plane (250); and the plurality of valleys (240) have a shallow part (245) receding relative to the first curvature in a direction to the central plane (250).

A lamp device is disclosed. The lamp device comprises a first electrical connector and a second electrical connector located at a first end portion of the lamp device. The first end portion of the lamp device is received in a receptacle of a first base portion. A first locking portion is included for secunng the first base portion to the first end portion. The present radiation lamp device obviates or mitigates the need to use adhesive and/or polymer insulation/O-rings to achieve electrical connections. Further, the present radiation lamp may be oriented in a vertical orientation without the need to use springs and/or rubber part to support the distal end of the lamp.