Field of the invention

The invention relates to an LED (Light Emitting Diode) light unit and specifically to a housing for a LED light unit.

Description of the related art

In LED light units, a plurality of LEDs may be mounted to a printed circuit board. This circuit board is often covered by a cover which may also act as a lens for guiding light to the outside of the light unit.

The European patent application publication EP 1 821 030 Al discloses an LED light unit, where LEDs are mounted to a heat sink. Furthermore, the LEDs are embedded by a cover element and a housing to form an integral part which is water-tight.

A disadvantage of this LED light unit is the complex design and the cover element embedding the LEDs which may affect optical characteristics.

Summary of the invention

The problem to be solved by the invention is to design a sealed LED light module which is sealed against dust, dirt, water and/or humidity, which has excellent long term stability and which can be manufactured by an automatic process in large volumes at low costs. The solutions of the problem are described in the independent claims. The dependent claims relate to further improvements of the invention.

A base plate supports at least one LED and/or further electronic components which may be required for driving/controlling the at least one LED. The base plate may be a printed circuit board. It may also comprise a printed circuit board. Preferably, the base plate is a heat conducting plate which may be made of a metal, like aluminum, and which further preferably comprises laminated isolating and current-conducting structures. The base plate is positioned on a cover through which light may be emitted from the at least one LED to the outside of the light module. The cover may have at least one lens for guiding and/or directing the light emitted by the at least one LED. Preferably, the cover is made of a clear and/or transparent and/or semitransparent material, preferably a plastic material. The cover preferably has at least one base plate support. Such a base plate support may be a strut or a protrusion from the inner surface of the cover.

Preferably, the base plate support is a bar or a barrier, preferably surrounding at least a part of the base plate. It is further preferred, if the cover has at least one sidewall which forms a trench together with the at least one base plate support. Most preferably this trench is surrounding the baseplate and/or the cover.

At least one edge of the base plate, preferably all four edges of a rectangular base plate are held within a sealing. The sealing preferably fixes the base plate to the cover. It preferably is the only connecting means between the base plate and the cover. Accordingly there is no screw, rivet or clip in between or surrounding the base plate and the cover. The sealing may be a mold or cast or glue. It preferably is at least a semi-elastic plastic material. Preferably, the sealing is contained within the trench defined by at least one base plate support and a side- wall of the cover. Preferably the sealing is processed by low pressure injection molding. It may be a hot-melt which may be based on polyamide. Preferably, the base plate and the cover form a hermetically sealed unit which preferably is water tight and which preferably cannot be opened and need not to be opened for service. This prevents the penetration of dust and debris into the optical system which also extends lifetime and improves quality. Most preferably the base plate has no further holes or openings except holes which are sealed and ventilation holes. Due to the elastic properties of the seal, different thermal expansion of the base plate and the cover may be equalized, therefore preventing cracks or even bending of the unit at extreme temperatures.

For easy assembly, the cover may be placed with its inside up on a flat surface. Then, the base plate may be placed on the cover. The base plate is preferably held at a correct distance to the cover by the at least one base plate support. There may be further notches or holes in the base plate, interacting with protrusions in the base plate support to ensure a correct location of the base plate on the cover. After placement of the base plate on the cover, sealing is filled and/or molded to the edges of the base plate, preferably filling the at least one trench. Here, the at least one trench may act as a molding form which holds the sealing when it is in a semi-liquid or liquid condition.

In a further preferred embodiment, there is at least one sealing sidewall located between the cover and the base plate for sealing the inner space between the cover and the base plate containing the at least one LED against the outer environment. The sealing sidewall may enclose an area within which a further hole or opening may be provided in the base plate and/or the cover. Such an opening may be used for contacting an electrical connector and/or for inserting a screw. The sealing sidewall may be extending from the cover and may be of the same material as the cover. In an alternative embodiment, the sidewall may be of a material which is the same as the sealing. There may be any combination of the sealings disclosed herein with a connector. Generally such a sealed opening pre- vents any debris or contamination from the connector to penetrate into the optical system.

In a further embodiment, there may be an upper sealing which further seals parts of the outer side of the base plate. This upper sealing preferably is of the same material as the first sealing. To simplify molding, it may be connected by at least one bar to the first sealing. The upper sealing may also extend from the outside of the base plate through the inner space between the base plate and the cover to the inner side of the cover, therefore also sealing the inner space against the environment.

In a further embodiment, there are cut-outs and/or protrusions at the edges of the base plate.

In another embodiment, the edges of the base plate are bent to further increase mechanical strength of the connection to the sealing and to increase the mechanical stability of the mechanical contact between the base plate and the sealing.

Description of Drawings

In the following the invention will be described by way of example, without limitation of the general inventive concept, on examples of embodiment with reference to the drawings.

Fig. 1 shows a sectional view of the sealed LED light module.

Fig. 2 shows a sectional view with sealing sidewalls extending from the cover to the surface of the base plate.

Fig. 3 shows a different embodiment of the sealing sidewalk Fig. 4 shows an embodiment providing a cut-out in the cover.

Fig. 5 shows an embodiment with an upper sealing to seal the outer side of the base plate.

Fig. 6 shows a further sealing protruding to the cover.

Fig. 7 shows a modified upper sealing protruding to the cover.

Fig. 8 shows an embodiment with a base plate having bent sidewalls is disclosed.

Fig. 9 shows an embodiment of bent sidewalls of the base plate.

Fig. 10 shows a top view of the light module.

In Fig. 1, a sectional view of a first embodiment of the invention is shown. A cover 100 holds a base plate 200, whereas fixing and sealing between the cover and the base plate is done by a sealing 300. The base plate has an outer side (on top in the figure) and an inner side directed towards the cover, the inner side holds at least one LED (Light Emitting Diode) 210, 220, and optionally further electronic components. The LEDs radiate light from the bottom side through the cover 100 to the outside of the light module. For better holding of the base plate, preferably at least one base plate support 130, 131 are provided within the cover. They are preferably protruding from the surface of the cover. Furthermore, it is preferred, if the cover has at least one sidewall 110, 111, which preferably forms at least one trench 141 which may be filled with sealing 300 which preferably seals the edges 206, 207 of the base plate 200. Between the base plate 200 and the cover 100, there is a sealed inner space 140. Furthermore, there is at least one sealing sidewall 150, 151 between the cover 100 and the base plate 200. This at least one sealing sidewall encloses a section of the base plate which may contain an opening 230, through which a connecting plate 260 may penetrate to enter into electric contact with at least one electrical connector (240,250). By this way, electrical connection may be made from the LEDs at the base plate to an external power supply. In combination with an opening in the cover 100, which may be similar to opening 180 from figure 4, but with shortened inner walls, to allow access to the base plate 200, a connector may be inserted from the front side of the cover. This may allow external access e.g. for diagnosis or control like dimming of the lamp and/or the power supply. The connector may also be extending from the power supply though the base plate to be accessed from the front side of the cover. It is further preferred to have guiding elements for the connector at least in one of the cover, base plate or inner walls. Preferably these guiding elements allow insertion of the connector from at least one side, preferably from both sides.

In Fig. 2, a further embodiment is disclosed. Herein, the opening in the base plate 230 is larger and may be used for a different purpose than inserting a connecting plate as disclosed before. In this embodiment, the sealing sidewalls preferably protrude from the cover 100 into the direction of the base plate 200 and end at the inner side of the base plate 200, which is bearing the at least one LED. It preferably comprises the same material as the cover 100.

In Fig. 3, a different embodiment of sealing sidewalls 150, 151 is disclosed. Here, the sealing sidewalls 150, 151 protrude from the cover 100 to the outside of the base plate 200, therefore providing a better sealing of the base plate.

In Fig. 4, a further embodiment is shown which provides an opening 180 in the cover. For this purpose, the sealing sidewalls 150, 151 extend from the cover 100 throughout the base plate 200. Contact of the sealing sidewalls may also be done as disclosed in Fig. 2. Such a cut-out in the cover may be used for gaining access to an electrical contact or to a screw. In Fig. 5, a further embodiment is disclosed having an upper sealing 190 to seal an area at the rear side of the base plate 200. To simplify molding and to have a connection between the upper sealing which preferably is made of the same material as the sealing 300, at least one bar 191 may be provided. This kind of sealing may be combined with any other kind of sealing sidewalls disclosed before.

In Fig. 6, a further sealing is disclosed which protrudes through the cover 100 and therefore seals or encapsulates the whole inner space.

In Fig. 7, a modified upper sealing is disclosed which protrudes through the cover 100 and therefore seals or encapsulates the whole inner space.

In Fig. 8, a modified embodiment is disclosed. Herein, the base plate 200 has bent sidewalls 201. These bent sidewalls further increase mechanical stability and stiffness of the base plate. They further increase the mechanical retention force of the base plate within the sealing 300 and therefore within the cover 100, further increasing mechanical stability of the sealed LED light module. It is obvious that this specific embodiment may be combined with all other embodiments shown herein.

In Fig. 9, a top view of a base plate 200 is shown. Herein, there are bars 202 connecting the bent sidewall 201 to the base plate 200. Between the bars, there are cut-outs 203. The sealing 300 penetrates through the cut-outs and therefore increases the retention of the base plate 200 within the sealing 300, further increasing mechanical stability. It is obvious that this specific embodiment may be combined with all other embodiments shown herein.

In Fig. 10, a top view of the light module is shown. The base plate 200 is placed on cover 100 and is sealed by sealing 300. Here, the second sidewall 111 and a third sidewall 112 can be seen. On top of the base plate 200, there is an upper sealing 190 connected by a bar 191 to the sealing 300. There may be a vent hole 205 in the base plate allowing for equalization of air pressure. This hole may have a filter, a membrane or other means for directing or selecting flow of vent exchange of gases, preferably preventing the intrusion of liquids or humidity. First protrusions 172 and second protrusions 174 may be provided for aligning the light module within a lamp case. Furthermore, it is preferred, if at least one clamp 170 is provided to fix the light module within a lamp case.

List of reference numerals

100 cover

110 first sidewall

111 second sidewall

112 third sidewall

130 first base plate support

131 second base plate support

140 inner space

141 trench

150 first sealing sidewall

151 second sealing sidewall

170 clamp

172 first protrusions

174 second protrusions

180 opening in cover

190 upper sealing

191 bar

200 base plate

201 bent sidewall

202 bar

203 cutout

205 vent hole

206, 207 edges of the base plate

210, 220 LEDs/components

230 opening in base plate

240 first connector

250 second connector connecting plate sealing