WO2002005356A1

WO2002005356A1 - Lamp with an led light source

Info

Publication number: WO2002005356A1
Application number: PCT/AT2001/000231
Authority: WO
Inventors: Bela Szenci; Manfred Gerger; Norbert GÖTTFRIED; Rainer Pfingstl; Vaclav Ulc
Original assignee: Hella Fahrzeugteile Austria Gmbh & Co Kg
Priority date: 2000-07-12
Filing date: 2001-07-12
Publication date: 2002-01-17
Also published as: AU2003250573A1; AU2002218797A1

Abstract

A lamp with an LED light source (3) comprises several unhoused LEDs and a projection optic. The LED dice are arranged on a circuit board made from thermally conducting material, or on a board together with a control circuit and preferably thermally connected to a cooling body by means of the rear face of the circuit board or board. A housing (1) and/or reflector (2) for the lights is provided as cooling body. The projecting optic can comprise a simple or multiple reflector (2), the form of which is formed by the inner side of the housing (1). In particular the LED light source (3) is arranged at the base of the reflector (2) and the reflector (2) cast using a highly transparent polymer.

Description

"Luminaire with an LED light source"

TECHNICAL AREA

The present invention relates to a luminaire with an LED light source comprising a plurality of unhoused LEDs and imaging optics, the LED dice being arranged on a circuit board made of thermally conductive material and the circuit board, preferably via its rear side, being thermally connected to a heat sink.

STATE OF THE ART

By processing LED ^"s in chip-on-board technology (COBT) efficient, high-intensity and small-area lighting units can be generated. Due to this fact and due to their robustness and long service life are DER-like light sources for use in vehicles of all types and very well suited for general applications (e.g. in the household area, in the signal area etc.).

Furthermore is to be considered in ^LED's, which are processed in COBT that these are to be thermally connected with a heat sink for dissipating the heat generated during operation by means of convection. A large cooling surface (between 5 and 15 cm per LED) is required for this.

A device of the type mentioned, in which the problem of cooling is well solved, is from the

US 5 936 353 A is known. The disadvantage is the space requirement and the weight of the heat sink.

DISCLOSURE OF THE INVENTION

It is an object of the present invention to overcome this disadvantage. 02/05356

- 2 -

This object is achieved according to the invention by a lamp of the type mentioned at the outset in that the heat sink is formed by a housing and / or by a reflector of the lamp. The housing or the reflector thus have a double function, which means that the space required for the heat sink is eliminated; should an additional heat sink be necessary, then this will at least take up less space.

The mapping of the LED light sources is essentially more demanding than for point-shaped light sources due to their areal expansion, especially since they are often defined

Light emissions in defined beam angles for lights in vehicles are required (see, for example, regulations for lighting equipment for motorized vehicles: applicable ECE regulations, SAE standards or FMVSS108 etc., regulations for boat lights according to IM072 and BSH as well as special national or international regulations or Customer standards).

In order to achieve the specified light emission, it is therefore preferably provided that the imaging optics have a single or multiple reflector, the shape of which is formed by the inside of the housing. The LED light source can be arranged at the base of the reflector and the reflector can be cast using a highly transparent polymer. This protects both the reflector and the LED light source and mechanically fixes the reflector. In order for the casting compound to withstand the heat during operation, the casting compound should have a glass transition greater than 100 ° C.

A cover plate, optionally with integrated lenses, can also be provided in order to additionally influence the light propagation.

A combination with a dome-shaped glob top is also possible.

In order not to impair the light propagation, it is expedient if the LED light source is electrically connected to control electronics, which is arranged on a separate circuit board, the circuit board of the control electronics also being thermally connected to the housing or to the reflector. The control board 02/05356

- 3 - The electronics are separated from the LED light source, but the cooling is still done via the same housing or the same reflector. Alternatively, the control electronics can be applied directly to the LED circuit board in such a way that the light propagation is not disturbed thereby.

The housing preferably has ribs or slots to increase the effective cooling surface. As a result, the outer dimensions of the housing can be reduced.

The diameter of the imaging optics should correspond 2 to 4 times the maximum distance of the dice on the circuit board. If it is smaller, it would affect the image quality. Larger versions would make the lamp unnecessarily large and heavy.

A special embodiment of the present invention is characterized in that it has a reflector which consists of several, preferably three, single or multiple reflector systems which are arranged in a circle, so that the lamp emits light horizontally over 360 ° and vertically over a defined angle. Such a lamp can be used as a boat lantern.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is explained in more detail with reference to the accompanying figures. 1 to 5 show different embodiments of housings 1 that can be used for a lamp according to the invention, and FIG. 6 shows a boat lantern.

BEST EMBODIMENT OF THE INVENTION

1-5, the reflectors have two different designs. The LED light source 3 is arranged in each case in its base (only shown in FIG. 1), the final exit angle of the emitted light through the reflector and / or an optically coupled light disk 5 (see FIG. 3) (Fresnel lens or Gauss 'see lens) is determined. 02/05356

The dice should be arranged as symmetrically as possible on the circuit board so that the emitting light has no preferred directions. The dice can e.g. be arranged in one or more rows, a rotationally symmetrical arrangement is also possible.

The housings 1 have slots 1 'to increase their surface area.

The space inside the reflector 2 and above the LED light source 3 can be phase-matched with a sealing compound 6 (see FIG. 4), in which case the final angle of propagation of the emitted light by suitable shaping of the exit surface 7 (in this case cylindrical convex) is determined from the reflector 2.

In the luminaire according to FIG. 6, three reflectors 2 are provided which are joined to one another in a circle in plan view, so that this luminaire covers 360 ° in the horizontal direction. LED light sources are provided at the base and thermally connected to the reflectors 2. There are metal disks 8, 9 at the top and bottom, which are thermally connected to the reflectors 2. They serve as a housing and also take over the heat dissipation.

A large number of the required emission colors can be realized with such luminaires due to the fact that LEDs can be produced in many different colors. However, special emission colors and in particular white emission cannot be realized with an LED, because LEDs generally have narrow-band emission spectra. Possibilities for realizing white light are e.g. in US 5 851 905 A, in WO 00/02262 A and in US 5 836 676 A.

Basically, two methods can be used to create these colors:

1) Color conversion: by placing a luminophore directly above the LED dice, which absorbs the emission of the dice and then emits photoluminescent light in a different emission color. 2) Color mixing: differently colored LED dice are arranged in a special ratio on a circuit board, and the emission color to be generated is set by defined setting of the operating conditions for the respective die type.

Both methods can be used for the production of special emission colors in the present invention. For technical applications, however, variant 2 has considerable advantages over variant 1, not least due to the fact that variant 2 does not require luminophores, which have only limited stability under irradiation. Variant 2 also allows the color location to be set by adjusting the current flow through both LED dice.

One possibility for generating white light according to variant 2 is that a white emission color is generated by a combination of blue and orange LED dice or by a combination of LEDs which emit σyan and red-orange. Furthermore, white light can be generated by a combination of red, green and orange or red LEDs.

In order to achieve an optimal light output per LED die, the relative ratio of the dice is chosen such that the desired color emission is achieved with maximum current flow per die. The determining factors here are the color locations of the LED dice and the relative intensity ratio of the dice for the selected operating parameters. In this way, white light is generated in the present invention by a combination of light from blue LEDs with a dominant emission wavelength between 470 and 485 nm and orange LEDs with a dominant emission wavelength between 570 and 590 nm.

Alternatively, in the present invention, white light is generated by a combination of light from blue LEDs with a dominant emission wavelength between 495 and 510 nm and orange LEDs with a dominant emission wavelength between 585 and 600 nm. A further alternative is white light through the combination of light from blue LEDs (Wavelength between 460 and 480 nm), green LEDs (500 to 530 nm) and orange LEDs (585 - 595 nm).

In this way, in the present invention, cyan-colored light is generated by a combination of light from blue LEDs with a dominant emission wavelength between 460 and 485 nm and green LEDs with a dominant emission wavelength between 520 and 540 nm.

Claims

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8. Luminaire according to one of claims 1 to 7, characterized in that the housing (1) has ribs or slots (1 ') to increase the effective cooling surface.

9. Luminaire according to one of claims 1 to 8, characterized in that the diameter of the imaging optics 2 to

4 times the maximum distance of the dice on the circuit board.

10. Luminaire according to one of claims 2 to 5, characterized in that it has a reflector (2) which consists of several, preferably three single or multiple reflector systems, which are arranged in a circle, so that the luminaire over 360 ° horizontally and Vertically emits light over a defined angle. (Fig. 6)