LAMP

摘要

An LED lamp has a tubular metal body (1) having bayonet fitting lugs (2) and a central insulated contact (3) at its base. The top (4) of the body is angled and has a small metal plate (5) set in potting compound (6) arranged flush with the angled top (4). The plate (5) has two arrays (7, 8) of LEDs mounted on it. They are protected by a layer of transparent encapsulant (9). The LEDs (7) are visible light LEDs, and up to two hundred of them are arranged in a series/parallel array (70). The LEDs (8) are infra-red LEDs, with four arranged in a series parallel array (80). The cathodes (71) of the LEDs (7) on the cathode side of the array (70) and the anodes (82) of the LEDs (8) on the anode side of the array (80) are commonly connected via leads (11) to the body (1). The anodes (72) on the anode side of the array (70) are connected via a current limiting resistor (12) to the central contact (3). Similarly the cathodes (81) on the cathode side of the array (80) are connected via a reverse voltage limiting diode (13) and a current limiting resistor (14) to the central contact (3). When the central contact has a positive voltage applied to it of say 28 volts, the VL LEDs (7) are excited, and emit light; whilst the IR LEDs (8) are not excited. When the polarity is reversed, the IR LEDs are excited and emit IR light and the VL LEDs are not excited.