Technical Field

The present invention relates to a device for comprehensive protection of LED sources for use in any outdoor weather conditions intended for high-power light emitting diodes (hereinafter only "LED") and applicable in all areas where these LEDs are used for lighting, especially in architecture, industry, roads and parks.

Background Art

Presently, to protect against weather conditions various lighting fixture designs are used which protect the LED source from the elements, comprising a lighting fixture body, LED assembly, heat sink, transparent protective cover and a seal, or possibly a number of small covers and seals protecting the LED assembly or the LED source from water, humidity, dust and polluted air containing various chemicals.

LED sources have a lifetime of about 50,000 hours, during which the most critical part in terms of protection from water, humidity and dust is the seal located between the transparent cover and the lighting fixture body, the lifetime of which is affected also by chemicals in the air. When temperature changes the air pressure in an enclosed lighting fixture also changes and acts on the seal in such a way that with the temperature rising the air pressure increases, creating an overpressure and pushing the seal from the lighting fixture outwards. In contrast, during cooling the air pressure decreases, creating negative pressure and stressing the seal in the inward direction.

Since lighting fixtures around the world work in outdoor conditions from about -40 °C to about 60 °C, with daily operating conditions changing, the seals are prone to damage resulting in penetration of moisture into the lighting fixture making it malfunction. LED source manufacturers tackle the described problem by using pressure relief valves.

As examples of the patent literature related to the issue in question there are mainly the following documents

- European patent application 2375130 pertaining to lighting for tunnels, roads and streets. It does not address the problem of malfunctioning due to changing weather conditions. - European patent EP2058584, which is the closest state of the art, pertains to a lighting fixture for illuminating outside public areas comprising of one or multiple light emitting diodes and corresponding refractive optical elements to channel the emitted light to one or multiple illuminated areas and its connection to a street lamp pole. To guarantee specified resistance to environmental factors, the proposed lighting fixture comprises a seal of the refractive optical elements. The issue is also the subject of, for instance, Japanese documents JP2011054348 and JP2005116182.

The purpose of the present invention therefore is to solve the above problem in the most optimal way.

Disclosure of Invention

It has been found that the described problem of potential malfunctioning of presently used equipment due to pressure changes in response to changing weather conditions can be resolved with high efficiency by the device of the present invention comprising at least one optical assembly consisting of at least one LED source placed on an an electrically powered a thermally conductive printed circuit board, a heat sink and an optical element. The subject matter of the invention lies in the fact that the optical element is placed over the LED source on a heat sink or a printed circuit board, directly or through an optical element holder (not depicted in drawings), and the said optical assembly is encapsulated in a watertight way into a compact waterproof module by means of a filling compound material. The location of the optical element protects the LED source from direct contact with the filling compound material and at the same time ensures the desired source beam angle.

It is important that the filling compound material was waterproof, weather resistant and that the encapsulation technology does not damage individual elements of the optical assembly. Epoxy and silicone filling compound materials have proven to be especially suitable.

As a result of this arrangement of the device of the invention the need for any seal as used in the prior art solutions is eliminated. This arrangement of the device at the same time compensates for thermal expansion of different materials the device is made of without affecting the LED source.

This arrangement also results in the volume of air that could be subject to pressure variations being minimal, thus preventing any negative or positive pressure build up within the device.

When the description of the present invention hereinafter refers to a LED source, a LED ARRAY source is also meant.

The apparatus of the present invention may further comprise a plurality of optical assemblies for LED ARRAY, with all of them being encapsulated in a single compact waterproof assembly.

The apparatus of the invention can be used for single-colour LEDs, multicolour (multi-chip) LEDs as well as for LED ARRAYS consisting of multiple LEDs.

As it has already been mentioned, the individual optical elements are positioned, directly or through an optical element holder, over the LED source, thus ensuring desired light beam angle. These optical elements also provide protection against the filling substance running into the LED sources.

Individual LED sources are connected to a power source providing adequate power for the LED sources or control electronics allowing to control the intensity of all high power single colour and/or multi-colour LED sources, with basic RGB colour mixing optionally enhanced by colour mixing with Amber, White, Neutral White, Warm White, Cyan and other colours, thus achieving more variable colour mixing.

The control electronics can be controlled remotely by any standard digital signal (such as DMX 512, MIDI, DALI, DSI, RS232, RS485, Instabus, C-bus, Profibus, intranet and internet, etc.).

Compact water resistant LED optical arrays may be conveniently mounted to an aluminium, copper, or ceramic heat sinks, either directly or through other contact elements such as thermally conductive tapes, thermally conductive paste, an active Peltier cell. The heat sink may be compact, or alternatively composed of several cooling components. Heat sinks are air-cooled and can be additionally cooled by a fan suitable for outdoor conditions with temperature based speed control or with constant speed and no speed control.

At extremely low temperatures the LED ARRAY optical assembly or a complementary resistive element themselves can be a source of heat.

For the case of extremely high temperatures, the device may also comprise a protection against sun rays.

Brief Description of Drawings

Examples of the embodiments of the present invention will be illustrated by the attached drawings in which

FIG. 1 shows a LED or LED ARRAY source placed on an electrically powered heat-conductive printed circuit board fixed to a heat sink with an optical element positioned over the LED or LED ARRAY source, which when sealed with a filling compound material is turned into a compact waterproof assembly, where the LED or LED ARRAY source is protected against the filling substance running in by the position of the optical element also ensuring the required source beam angle.

FIG. 2 shows a LED or LED Array source, placed on an electrically powered heat-conductive printed circuit board fixed to a heat sink where the LED or LED ARRAY source is fixed to the heat sink in at least two rows, with optical elements positioned over the LED or LED ARRAY sources. Encapsulating it in a filling substance turns it into a compact waterproof LED or LED ARRAY assembly. LED or LED ARRAY sources are protected by the position of the optical element against the filling substance running in, which also ensures required source beam angles.

Fig. 3 shows a LED or LED ARRAY source placed on an electrically powered and heat- conductive printed circuit board fixed to a heat sink with an optical element, which when sealed with a filling substance is turned into a compact waterproof LED assembly connected to a power source providing necessary power, or alternatively control electronics and when assembled together by means of couplers they create a lighting fixture, the optical elements of which are protected by a transparent protective cover.

FIG. 4 shows a LED or LED ARRAY sources, placed in several rows on an electrically powered heat-conductive printed circuit board fixed to a heat sink with optical elements positioned on the heat sink over the LED or LED ARRAY sources. Potting it with a filling compound material turns it into a compact waterproof LED or LED ARRAY assembly connected to a power source providing necessary power, or alternatively to control electronics and when assembled together by means of couplers they create a lighting fixture protected against sun rays by a protective cover. LED or LED ARRAY sources are protected by the position of the optical elements against the filling substance running in, which also ensures required source beam angles.

It is understood that the individual embodiments of the device of the present invention are shown by way of illustration only and not as limitations. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the invention. Such equivalents are intended to be encompassed by the following claims. It should be understood that the following examples of the embodiments of the device of the invention are shown only as examples illustrating its technical use and those skilled in the art will recognize possible alternatives of these embodiments and uses, even if they are not explicitly stated. Those skilled in the art will recognize actual dimensioning as well as alternative design and material solutions for the device as such and its individual components.

To those familiar with the state of the art it cannot be a problem to choose materials and structural arrangements which were not dealt with in detail but falling within the scope of the following claims.

Modes for Carrying Out the Invention Example 1

Shown is a device with a LED ARRAY source I placed on an electrically powered heat- conductive printed circuit board 4 with an integrated group of optical elements 3. These optical elements cover the LED ARRAY in precise positions. This printed circuit board is fixed to a heat sink 2 also creating borders of the space which filling compound material 5 is poured into during the device assembly.

This creates a compact waterproof module of an optical LED assembly connected to a power source 6 providing required power or alternatively to control electronics 6. The optical elements are then further protected by a protective cover 7. In case of direct sunlight A and high temperatures associated therewith the compact waterproof module of the LED optical assembly is protected by a protective cover 9. Example 1 is shown in Fig. 5.

If control electronics 6 are used, the device of the present invention can also be controlled remotely by any standard digital signal (such as DMX 512, MIDI, DALI, DSI, RS232, RS485, Instabus, C-bus, Profibus, intranet and internet, etc.). Example 2

Shown is a device with a LED ARRAY source I placed on an electrically powered heat- conductive printed circuit board 4 with an integrated group of optical elements 3. These optical elements cover the LED ARRAY in precise positions depending on the desired beam angle. This printed circuit board is fixed to a heat sink 2 also creating borders of the space which filling compound material 5 is poured into. This creates a compact waterproof LED assembly connected to a power source 6 providing required power or to control electronics 6. The optical elements are further protected by a protective cover 7. In case of direct sunlight A and the effect of high temperatures associated therewith the compact waterproof module of the LED optical assembly is protected by a protective cover 9. Example 2 is shown in Fig. 6.

If control electronics 6 are used, it can also be controlled remotely by any standard digital signal (such as DMX 512, MIDI, DALI, DSI, RS232, RS485, Instabus, C-bus, Profibus, intranet and internet, etc.).

Industrial Applicability

The device of the invention can be applied in all types of LED lights for outdoor use, such as: Asymmetrical beam lights, symmetrical beam spot and wash lights intended primarily for street and park lighting, architectural floodlights for lighting buildings, fountains, outdoor areas, parking lots, and in any other outdoor environment with high demands on LED ARRAY protection from the weather conditions.