TECHNICAL FIELD

The present invention relates to a LED-luminaire for electric lighting. PRIOR ART

Luminaires equipped with LED-chips are known in various designs. It is also known to use so called COB modules (Chip On Board) having LED-chips bonded onto a PCB (printed circuit board). Many chips can be placed on little space, where they collectively create high luminous fluxes. COB modules can be made slim and thereby have low space requirements.

DESCRIPTION OF THE INVENTION

It is an object of the present invention to provide a LED-luminaire having an organic shape designed for multi purpose usage of lighting. The design shall be suitable for high volume automated mass production lines and shall be scalable. This object is achieved by a LED-luminaire as characterized in claim 1 . The inventive LED-luminaire is accordingly characterized in that it comprises a disc shaped luminous element, wherein the luminous element is made of a base, a transparent/translucent diffuser cover and a PCB-assembly, wherein the base and the cover have an outer rim part each, such rim parts being engaged with each other in the form of a snap fitting key and slot joint in an engaging direction, wherein the PCB-assembly is held in place by and between the base and the cover and is provided with a multiplicity of LED-chips, wherein an inner part of the base is recessed with regard to the outer rim part thereof, wherein input entries are provided at said inner part allowing end portions of connecting wires to be inserted in 5 an almost perpendicular orientation with regard to said engaging direction, and wherein a front part of the cover is convex with regard to the outer rim part thereof.

By the invention the following advantages are achieved:

The complete LED-luminaire is composed of only three main components which 1 0 can effectively be produced and assembled by operations in the engaging direction in an online process. The said three main components are also assembled screwless, this being as well ideal for high volume automated mass production lines. The inventive LED-luminaire is provided with an innovative integrated input entry of wires. By the innovatively shaped transparent/translucent diffuser cover a i s very low wall thickness is possible and thereby minimum optical losses during light transmission and good heat transmission are achieved.

Preferred embodiments of the inventive LED-luminaire are characterized in the dependent claims. BRIEF DESCIPTION OF THE DRAWINGS

The invention will beconne readily apparent from the following detailed description of preferred embodiments in connection with the attached drawings: In the drawings:

Fig. 1 shows an isometric top view of a disc shaped luminous element forming a LED-luminaire according to the invention or a part of it.

Fig. 2 shows an isometric rear view of the element of Fig. 1 .

Fig. 3a shows a top view of the element of Fig. 1 .

Fig. 3b shows a left view of the element of Fig. 1 .

Fig. 3c shows a front view of the element of Fig. 1 .

Fig. 4 shows a rear view of the element of Fig. 1 .

Fig. 5 shows the base, the PCB-assembly and the transparent/translucent diffuser cover of the element of Fig. 1 separated in a blow-up view.

Fig. 6a shows a top view of the element of Fig. 1 .

Fig. 6b shows a partial sectional view (A-A in Fig. 6a) of the element of Fig. 1 . Fig. 6c shows a partial sectional view (C-C in Fig. 6a) of the element of Fig. 1 . Fig. 6d shows a partial sectional view (B-B in Fig. 6a) of the element of Fig. 1 .

Fig. 7 shows a top view of the element of Fig. 1 with the diffuser cover removed.

Fig. 8a shows a rear view of the element of Fig. 1 .

Fig. 8b shows a partial sectional view (D-D in Fig. 8a) of the element of Fig. 1 .

Fig. 9 shows an isometric top view of a first frame for a recess mounting of the element of Fig. 1 .

Fig. 1 0 shows an isometric rear view of the first frame of Fig. 9 connected to the element of Fig. 1

Fig. 1 1 a shows a rear view of the first frame of Fig. 9 connected to the element of Fig. 1 .

Fig. 1 1 b shows a right side view of the first frame of Fig. 9 connected to the element of Fig. 1 .

Fig. 1 1 c shows a top view of the first frame of Fig. 9 connected to the element of Fig. 1 .

Fig. 1 1 d shows a front view of the first frame of Fig. 9 connected to the element of Fig. 1 . Fig. 1 2 shows the first frame and the element of Fig. 1 separated in a blow-up view.

Fig. 1 3 shows the frame part of the first frame of Fig. 9 and associated clips for snap-ping into a cut-out of a mounting plate separated in a blowup view.

Fig. 1 4a shows a rear view of the first frame of Fig. 9.

Fig. 1 4b shows a partial sectional view ( D-D in Fig. 1 4a) of the first frame of Fig.

9.

Fig. 1 5a shows a top view of the first frame of Fig. 9

Fig. 1 5b shows a partial sectional view (E-E in Fig. 1 5a) of the first frame of Fig.

9 connected to the element of Fig. 1 .

Fig. 1 6 shows an isometric top view of a second frame for a recess mounting of the element of Fig. 1 .

Fig. 1 7 shows an isometric rear view of the second frame of Fig. 1 6 connected to the element of Fig. 1

Fig. 1 8a shows a rear view of the second frame of Fig. 1 6 connected to the element of Fig. 1 . Fig. 1 8b shows a right side view of the second frame of Fig. 1 6 connected to the element of Fig. 1 .

Fig. 1 8c shows a top view of the second frame of Fig. 1 6 connected to the element of Fig. 1 .

Fig. 1 8d shows a front view of the second frame of Fig. 1 6 connected to the element of Fig. 1 .

Fig. 1 9 shows the second frame of Fig. 1 6 and the element of Fig. 1 separated in a blow-up view.

Fig. 20 shows the frame part of the second frame of Fig. 1 6 and associated clips for snapping into a cut-out of a mounting plate separated in a blow-up view.

Fig. 21 a shows a rear view of the second frame of Fig. 1 6. Fig. 21 b shows a partial sectional view (F-F in Fig. 2 1 a) of the second frame of

Fig. 1 6.

Fig. 22a shows a top view of the second frame of Fig. 1 6.

Fig. 22b shows a partial sectional view (G-G in Fig. 22a) of the second frame of

Fig. 1 6 connected to the element of Fig. 1 . Fig. 23 shows in a schematic representation a partial top view of the PCB- assembly of the element of Fig. 1 .

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Figures 1 , 2, 3a, 3b, 3c and 4 show different views of a disc shaped luminous element 1 0 which forms a LED-luminaire according to the invention or a part of such a luminaire. In the top view element 1 0 is almost quadratic with rounded corners and slightly outwardly curved outer sides. Two screw holes 1 1 extending through element 1 0 are provided for a surface mounting using screws (not shown). A further part of a LED-luminaire according to the invention may be formed by a frame 60 as shown in Fig. 9 or a frame 70 as shown in Fig. 1 6 for a recess mounting of element 1 0.

As can be seen from the blow-up view of Fig. 5, element 1 0 is made of three main components, namely a base 20, a PCB-assembly 40 and a transparent/translucent diffuser cover 30. The direction in which such components are engaged (engaging direction) with each other is de-noted by an arrow. The PCB- assembly 40 is provided with a multiplicity of LED-chips, of which only one is denoted by 41 .

As can be seen from Fig. 2, base 20 has an outer rim part 21 with regard to which an inner part 22 is recessed. Inner part 22 is almost flat, just having four low stabilizing rips 23 at its rear side. At the inner part 22, adjacent to the outer rim part 21 , input entries 24 are provided allowing end portions 51 of connecting wires 50 - for connecting the luminous element 1 0 to an electric power supply (see Fig. 8a-b) - to be inserted in an almost parallel orientation with regard to the inner part 22, i.e. in a perpendicular orientation with regard to said engaging direction. Associated with the input entries 24 is a button 25. Pressing such button 25 allows or at least eases the insertion of removal of said end portions 51 of connecting wires 50. Both, input entries 24 and button 25 project outwards from the inner part 22 but not beyond the outer rim part 21 . Base 20, including input entries 24 and but-ton 25, is made in one piece.

Transparent/translucent diffuser cover 30 is made in one piece, too and has an outer rim part 31 and a front part 32. Front part 32 is curved in two dimensions in a convex manner with regard to outer rim part 3 1 . The maximum elevation of the convex form may be between 2.5mm and 50mm or more of its largest diameter depending on the size of the Luminaire. The convex form has a stabilizing effect allowing front part 32 to be provided with a small wall thickness. This is advantageous with regard to light transmission and heat dissipation from the LED-chips 41 . The wall-thickness of the front part 32 may be less than 1 mm, preferably even less than 0.7mm. The convex form also generates a wide beam angle. The rounded corners and the curved outer sides have a positive effect on the stability, too.

As can be seen from Figures 6 b-d, the outer rim part 2 1 of base 20 and the outer rim part 31 of transparent/translucent diffuser cover 30 are engaged with each other in the form of a snap fit-ting key and slot joint in said engaging direction whereby the outer rim part 21 of base 20 forms the slot part and the outer rim part 31 of cover 30 forms the key part of this snap fitting key and slot joint.

Base 20 and cover 30 are preferably produced by injection moulding. For that purpose such components are designed devoid of undercuts with respect to the engaging direction allowing the use of a simple two-part injection mould rather than an injection mould provided with moveable cores. This reduces both complexity and component production cycle time.

PCB-assembly 40 is held in place between base 20 and cover 30, lying with its rear side flatly on the inner side of inner part 21 of base 20. In addition there bushes for through holes 1 1 provided at base 20, one of which is denoted by 26. Such bushes 26 fitting into recesses 45 keep the PCB-assembly 40 centered in the base 20. On the front side of PCB-assembly 40 there is some free space between the PCB-assembly 40 and the front part 32 of cover 30, bridged by ribs 33. On this front side PCB-assembly 40 is provided with said multiplicity of LED-chips 41 . The light produced by LED-chips 41 is transmitted through the front part 32 of transparent/translucent diffuser cover 30.

As can be seen from Figures 6d and 7, PCB-assembly 40 is further provided on its front side with a few electronic devices 42 for supplying the LED-chips 41 with electric power, preferably directly from a mains supply. In this case additional extern equipment is not required for the operation of the LED-luminaire. The very low component count for driving the LED-chips 41 is achieved through the appli- cation of a specific integrated circuit. Electronic de-vices 42 are also small in size and fit into the regular matrix pattern of LED-chips 41 .

As already set forth above, the connection to an electric power supply is made by means of connecting wires 50, end portions 5 1 of which are to be inserted into input entries 24. As can be seen from Fig. 8b the end portions 51 need just to be slightly bended for insertion into input entries 24. Inside input entries 24 end portions 51 come into clamping engagement with two plate like metal contacts which are bonded to the PCB-assembly and are in electrical connection with electronic devices 42. By pressing button 25 metal contacts become deflected. Thereby the insertion or a removal of the end portions 51 of connecting wires 50 is easily possible.

The LED-chips 41 are bonded to PCB-assembly 40 in a regular matrix pattern. As can be seen from Fig. 23, almost the entire surface area of PCB-assembly 40 on its front side except of the areas used for tracks is filled with copper. By such copper pads, of which one is denoted by 44, heat dissipation from the LED-chips 41 is supported and the need of additional heat sinks for thermal management is eliminated. On the other hand, the front side of PCB-assembly 40 may additionally be provided with a thin white and reflective coating (not shown) for supporting the light emittance of the LED-chips 41 . Such coating is not yet applied in the schematic representation of Fig. 23.

Fig. 9 shows a frame according to a first embodiment of such a frame - referred to as first frame 60 in the following - that may be used for a recessed mounting of the disc shaped luminous element 1 0 in a cut-out of a mounting plate (not shown). As becomes apparent from Figures 1 0- 1 2 and 1 5a-b, first frame 60 is connectable to cover 30 in the engaging direction (denoted by an arrow) by means of several small snap fitting joints in the engaging direction. At the side of first frame 60 such joints are build-up by small hooks at the rear side of first frame 60 of which one is denoted by 61 . At the side of cover 30 the corresponding elements of such joints are build-up by small recesses with which hooks 61 come into engagement. One of such recesses is denoted by 34 in Fig. 1 2. First frame 60 is further provided with suitably curved clips 62. Such clips 62 snap into a suitable cut-out in a mounting plate (not shown) when the assembly of disc shaped luminous element 1 0 and first frame 60 is pressed into the cut-out in the engaging direction. For additionally stabilizing such assembly in the cut-out laterally, a ridge 65 is provided at the rear side of first frame 60 which also engages the cut-out. Ridge 65 has a quadratic shape and is circumferentially closed.

As can be seen from Fig. 1 3 clips 62 are separate parts. For connection to first frame 60 clips 62 are provided with hook shaped end portions 63. At first frame 60 slots 64 are provided in which clips 62 are inserted in the engaging direction. Slots 64 have undercuts which have a one way effect once clips 62 are inserted therein. Figures 1 4a-b show this type of connection of clips 62 to first frame 60. Due to clips 62 being separate parts first frame 60 may be produced by injection moulding using a simple two-part injection mould without moveable cores. Clips 62 may as well be injection moulded parts made from a plastic material, thereby replacing the conventional metallic spring clips for fixing recessed luminaire. Figures 1 6, 1 7, 1 8a-d, 1 9, 20 21 a-b and 22a-b show in the same manner as Figures 9 - 1 5 a frame according to a second embodiment of such a frame - referred to as second frame 70 in the following - that may also be used for a recessed mounting of the disc shaped luminous element 1 0 in a cut-out of a mounting plate (not shown). The design of the second frame 70 is similar to that of the first frame 60. It is also provided with small hooks at the rear side one of which is denoted by 71 and which come into engagement with recesses 34 at cover 30. The second frame 70 is also provided with dips 72 as separate elements having hook shaped end portions 73 for insertion into slots 74. Different from the first frame 60 second frame 70 has a greater outer size and is thereby better suited for retrofit applications in which a larger cut-out is already existing in a mounting plate from a previous fixture. Further different from stabilizing ridge 65 of first frame 60 second frame has several stabilizing ridge portions one of which is denoted by 75. Such ridge portions are arranged in a circle.

The design of the inventive LED-luminaire is freely scalable within a wide range. For example, the size of a diagonal of the disc shaped luminous element 1 0 may by chosen between 75mm and 650mm in combination with a thickness between 0.8mm and 2mm. In the top view element 1 0 need not be quadratic but could be oblong, oval or even circular as well. Depending on the size, the number of LED- chips on the PCB-assembly may vary between 64 - 400. The area required for each LED will be between 1 .25cm ² and 2cm ² . The LED-chips may individually have a power 0.1 - 1 Watt. It is preferred not to paint any surface parts of the inventive LED-luminaire for ecological reasons and for achieving durability and long life. Surface structures such as by the inscriptions on the different parts shown in the drawings may be achieved by moulding, chemical etching or by an EMD-process.

The base 20, the cover 30, the frames 60, 70 and/or the clips 62, 72 may be made from a plastic material such as PC (Polycarbonate) or PC/ABS (Polycarbon- ate/Acrylnitril Butadien Styrol) in case high mechanical strength is required and/or from PM A (Polymethyl-methacrylate) for superior optical characteristics.

The LED-luminaire according the invention and as described by example here before is generally characterized by a highly industrialized design best suited for mass production.

REFERENCE SIGNS

1 0 disc shaped luminous element

1 1 screw holes

20 base

21 outer rim part of base

22 inner part of base

23 stabilizing rips

24 input entries

25 button

26 bushes

30 transparent diffuser cover

31 outer rim part of cover

32 front part of cover

33 ribs

34 recesses

40 PCB-assembly

41 LED-chips

42 electronic devices

44 copper pads

45 recesses

50 connecting wires

51 end portions of connecting wires

60 first frame

61 hooks

62 clips

63 hook shaped end portions of clips

64 slots

65 stabilizing ridge

70 second frame

71 hooks

72 clips

73 hook shaped end portions of clips

74 slots

75 stabilizing ridge portions