Support arm lamp (central axis)

Detailed application description

Description of problem:

The central axis of an operating light consists of a vertical axis and horizontal cantilever mechanisms or arms. Between one and three cantilever mechanisms can be mounted on the axis. The central axis is fixed to the ceiling of the operating theatre. The parts are solidly designed, resulting in an axial diameter of 50 to 80 mm, because heavy loads have to be attached. The dimensioning of the cantilever depends on the axial loads. A slim central axis and cantilever mechanism enhance the aesthetic appearance. However, together with the electrical requirements as well as two load slip rings and up to six signal slip rings, this means very tight dimensions at the slip ring. Simple, secure installation, space limitations and high power density are key factors for slip ring design.

Description of solution:

LTN developed the SA120 encapsulated slip ring unit with an outer diameter of 120 mm, an inner diameter of 80 mm and 68 mm wide. It includes two load slip rings (each rated for up to 12 A) for the surgical lighting plus six signal slip rings (max. 2 A) for lamp control and video transmission. The load slip rings have silver graphite contacts. The brass ring has an additional hard silver coating and acts as a mating surface. Optimal slip ring performance is guaranteed immediately regardless of the motion profile. The same applies to the signal slip rings, which achieve very low transmission resistances with a hard gold-plated surface and modified gold-plated sliding contacts. Not only the high power density but all other customer requirements are met by the slip ring. The rugged polycarbonate housing protects the sensitive slip ring contacts, ensuring secure installation. The closed design renders adjustment of the brushes relative to the rings superfluous. Owing to the customised housing geometry, the slip ring is automatically installed in the correct position.