Lighting device with built-in RF antenna
A lighting device, such as a replacement lighting device, comprising a light source (LS), e.g. LEDs, for producing light along an optical axis (OA). A heat sink (HS) made of a material with an electrical resistivity being less than 0.01 Ωm, e.g. a metallic heat sink being a part of the housing, transports heat away from the light source (LS). A Radio Frequency (RF) communication circuit (CC) connected to an antenna (A) serves to enable RF signal communication, e.g. to control the device via a remote control. Metallic components, including the heat sink (HS), having an extension larger than 1/10 of a wavelength of the RF signal are arranged below a virtual plane (VP) drawn orthogonal to the optical axis (OA) and going through the antenna (A). Hereby a compact device can be obtained, and still a satisfying RF radiation pattern can be obtained. The antenna can be a wire antenna or a PCB antenna, e.g. a PIFA or a IFA type antenna. In a special embodiment the antenna is formed on a ring-shaped PCB with a central hole allowing passage of light from the light source. Preferably, the antenna is positioned at least 2 mm in front of the heat sink (HS).
1. A lighting device, comprising
a light source comprising one or more light-emitting diodes configured for generating light along an optical axis,
a heat sink comprising a metal with an electrical resistivity being less than 0.01 Ωm, and configured for removing heat produced by the light source, the heat sink forming at least a portion of an outer enclosure,
a RF communication circuit, and
a first antenna connected to the RF communication circuit for communicating RF control signals and arranged within the outer enclosure, wherein the lighting device comprises one or more metallic components having an extension larger than at least 1/10 of a wavelength of the RF control signals and arranged below a virtual plane drawn orthogonal to the optical axis and going through the first antenna.
2. Lighting device according to claim 1 , wherein the metallic components are arranged at least 4 mm below the virtual plane drawn orthogonal to the optical axis and going through the antenna.
3. Lighting device according to claim 1 , wherein the antenna is arranged at least 2 mm in front of the heat sink.
4. Lighting device according to claim 1 , wherein the first antenna comprises a radiating part substantially extending in one single plane being substantially perpendicular to the optical axis.
5. Lighting device according to claim 1 , wherein the first antenna is a wire antenna.
6. Lighting device according to claim 1 , further comprising a first printed circuit board, wherein the first antenna is one of an IFA antenna, a PIFA antenna, a Yagi antenna, and a loop antenna and is disposed on the first printed circuit board.
7. Lighting device according to claim 6 , further comprising a second printed circuit board substantially perpendicular to the first printed circuit board and the optical axis, wherein the first antenna is disposed on an end part of the first circuit board arranged for being received in an opening of the second printed circuit board.
8. Lighting device according to claim 6 , wherein the RF communication circuit is disposed on the first printed circuit board, such as the RF communication circuit being disposed on one side of the first printed circuit board, while the first antenna is disposed on an opposite side of the first printed circuit board.
9. Lighting device according to claim 6 , wherein the first printed circuit board has an opening, and is positioned in relation to the light source such that light can pass from the light source out of the enclosure through the opening in the first printed circuit board, such as the first printed circuit board being substantially ring-shaped.
10. Lighting device according to claim 1 , further comprising a second antenna, wherein the first and second antennas are oriented so as to radiate RF signals in different directions, the first and second antennas being different types of antennas.
11. Lighting device according to claim 1 , comprising a control circuit arranged to control a function of the lighting device in accordance with data received in an RF signal received via the RF antenna and the RF communication circuit.