Illumination device including doppler sensor
View Patent ↗An illumination device includes a cover; a lamp including a light emitting unit; and a doppler sensor including a receiving unit, disposed on the same side as the lamp with respect to a first plane including a surface of the cover facing the lamp. In a cross section that intersects the receiving unit and is orthogonal to a central axis of the light emitting unit, “θ” between a boundary line of a detectable range of the receiving unit close to the lamp and a normal to the first plane, “d” between the central axis and the first plane, “r” of the light emitting unit; “y” between the first plane and the receiving unit; and “x” between the receiving unit and a second plane that includes the central axis of the light emitting unit and is orthogonal to the first plane satisfy the following equation. x > ( y + d ) tan θ = r cos θ
1. An illumination device comprising:
a cover having a flat plate shape;
a straight tube fluorescent lamp including a cylindrical light emitting unit, the fluorescent lamp being disposed at one side of the cover in a thickness direction thereof, the cover being substantially in a parallel relationship with a central axis of the light emitting unit of the fluorescent lamp; and
a doppler sensor disposed on the same side as the fluorescent lamp with respect to a first plane including a surface of the cover which faces the fluorescent lamp, the doppler sensor including a receiving unit for receiving an electric wave from a detectable range having a part of the first plane,
wherein, in a cross section that intersects the receiving unit and is orthogonal to the central axis of the light emitting unit of the fluorescent lamp, an angle “θ” between a boundary line of the detectable range close to the fluorescent lamp and a normal to the first plane, a distance “d” between the central axis of the light emitting unit and the first plane, a radius “r” of the light emitting unit; a distance “y” between the first plane and the receiving unit; and a distance “x” between the receiving unit and a second plane that includes the central axis of the light emitting unit and is orthogonal to the first plane satisfy the following equation
x
>
(
y
+
d
)
tan
θ
+
r
cos
θ
.
2. The illumination device of claim 1 , wherein at least a part of the doppler sensor is not overlapped with the cover when viewed in the thickness direction of the cover.
3. The illumination device of claim 1 , wherein the doppler sensor is disposed around an axially central portion of the light emitting unit of the fluorescent lamp.
4. The illumination device of claim 1 , wherein the distance y is larger than the distance d.
5. The illumination device of claim 1 , wherein the doppler sensor is disposed below the fluorescent lamp.