Lamp for an external warning light

• US 6,268,702 B1
• Filed: 07/07/2000
• Issued: 07/31/2001
• Est. Priority Date: 11/12/1996
• Status: Expired due to Term

• Current Assignee: LFD Ltd. (ANZ Group Holdings Ltd.)
• Original Assignee: LFD Ltd. (ANZ Group Holdings Ltd.)
• Inventors: Fleck, Leonard
• Primary Examiner(s): VU, DAVID HUNG
• Application Number:
  US09/611,824
• Time in Patent Office: 389 Days
• Field of Search: 362/545, 362/230, 362/231, 340/815.45, 315/312, 315/185.R, 315/193, 315/192
• US Class Current: 315/185.00R
• CPC Class Codes: B64D 2203/00 Aircraft or airfield lights using LEDs
• CPC Class Codes: B64D 47/06 for indicating aircraft presence
• CPC Class Codes: F21K 9/23 Retrofit light sources for lighting devices with a single fitting for each light source, e.g. for substitution of incandescent lamps with bayonet or threaded fittings
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• CPC Class Codes: H05B 45/357 specially adapted for retrofit LED light sources
• CPC Class Codes: H05B 45/395 Linear regulators
• CPC Class Codes: Y02B 20/30 Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Abstract

A 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. The LEDs 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.

Claims

1. A lamp for an external warning light comprising:

a body providing a drive terminal and a return terminal,

a carrier mounted on the body,

a series/parallel array of a plurality of visible light, light emitting diodes (VL LEDs) arranged on the carrier mounted on the body,

a current limiting device mounted within the body for limiting current drawn by the VL LEDs, the current limiting device being connected in series with the array of VL LEDs, with the array and the limiting current being connected between the drive terminal and the return terminal and

at least one infra-red light emitting diode (IR LED) arranged on the carrier in like manner to the VL LEDs,

each IR LED and the VL LED array being respectively oppositely connected between the drive terminal and the return terminal, whereby application of voltage of one polarity will illuminate either each IR LED or the VL LEDs and voltage of the opposite polarity will illuminate the other(s) of the VL LEDs of each IR LED.

2. A lamp according to claim 1, including a plurality of the IR LEDs arranged in another series/parallel array or a parallel array.

3. A lamp according to claim 2, wherein there is an order of magnitude more VL LEDs than IR LEDs.

4. A lamp according to claim 1, including an optical screen, each IR LED being placed adjacent the optical screen, whereby the lamp can be arranged in use for the infra-red light to be emitted upwards only with the screen intercepting downward infra-red light.

5. A lamp according to claim 1, including a forward voltage regulation resistor connected in series with each IR LED as an electrical protection device.

6. A lamp according to claim 1, including a reverse voltage limiting diode, connected in series with each IR LED as an electrical protection device.

7. A lamp according to claim 5, wherein the values of the LEDs and the forward voltage regulation resistor are such that the lamp is adapted to be powered at one voltage (with one polarity) for illumination of the VL LEDs and another voltage (with the opposite polarity) for illumination of each IR LED.

8. A lamp according to claim 6, wherein the values of the LEDs and the reverse voltage limiting diode are such that the lamp is adapted to be powered at one voltage (with one polarity) for illuminating of the VL LEDs and another voltage (with the opposite polarity) for illumination of each IR LED.

9. A lamp according to claim 1, wherein the body is a bayonet fitting body adapted to co-operate with a bayonet fitting socket, with the drive terminal being a central terminal and the return terminal being bayonet fitting lugs.

10. A lamp according to claim 1, wherein the current limiting device is a resistor.

11. A lamp according to claim 1, wherein the current limiting device is an integrated circuit device in series with the VL LEDs, adapted to limit forward current through them when their resistance falls on heating in use.

12. A lamp according to claim 11, including a forward voltage regulation resistor connected in series with the VL LED array and the integrated circuit, forward current limiting device.

13. A lamp according to claim 1, wherein the carrier comprises a ceramic substrate on which the VL LED array and each IR LED are mounted, and transparent materials covers both the VL LEDs and each IR LED.

14. A lamp according to claim 13, wherein the ceramic substrate is mounted on a metal heat sink.

15. An aircraft lighting circuit for operating one or more lamps according to claim 1, the circuit including an opposite voltage generation circuit and a switch arranged to switch the polarity of voltage applicable to lamp(s), fitted in the circuit for illuminating the VL LEDs with one polarity and each IR LED with the other polarity.

16. An aircraft lighting circuit according to claim 15, including a differential amplifier circuit to which the switch is connected for switching on alternative inputs of the amplifier and a power output circuit for powering the VL LEDs or each IR LED at respective voltages in accordance with the position of the switch.

17. An aircraft light circuit according to claim 15, wherein the opposite voltage generation circuit is adapted to generate a voltage of one polarity which is an order of magnitude higher than that of the other polarity.