| 摘要 |
A motion detector based on mirrored optics for use in decorative lighting fixtures. The motion detector includes a mirror assembly that may be disposed within decorative elements such as saucers and chimneys that are common elements of lighting fixtures. Apertures are defined in the decorative element to admit infra-red radiation, which impinges on the mirror assembly. The mirror assembly comprises a plurality of opaque elongate members that are azimuthally spaced about a central longitudinal axis in such a way as to define an alternating sequence of open elongate slots and opaque elongate members. Each elongate member is formed with a mirror face on its inner surface which is generally facing the central longitudinal axis, and a PIR sensor is also disposed at the longitudinal axis. The elongate members and mirror faces define a plurality of detection zones in the motion detector field of view at two different vertical levels of view, each vertical level of view having a characteristic optical path associated with it. In a first optical path for monitoring the field of view in the far zones, infra-red radiation passes from an associated zone through one of the slots between two elongate members and is reflected from one of the mirror faces and concentrated onto the sensor. In the second characteristic optical path for monitoring the field of view in the near zones, infra-red radiation passes from an associated zone through one of the slots and on to the sensor without being deflected by any of the mirror faces. These two types of optical paths may be achieved in a full 360 degree zonal pattern for both the far zone and the near zone. The mirror assembly avoids the need for Fresnel lens optics.
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