WO2009037645A2

WO2009037645A2 - Led package

Info

Publication number: WO2009037645A2
Application number: PCT/IB2008/053763
Authority: WO
Inventors: Wouter P. Kaandorp; Jan Kloosterman; Josef A. Schug
Original assignee: Philips Intellectual Property & Standards Gmbh; Koninklijke Philips Electronics N.V.
Priority date: 2007-09-20
Filing date: 2008-09-17
Publication date: 2009-03-26
Also published as: TW200931683A; WO2009037645A3

Abstract

It is provided a LED package (10) for use in a lamp, particularly headlight or taillight of a motor vehicle, comprising a substrate (12) comprising an upper surface (18), at least one lighting element (14) for emitting light via an emitting surface (40) pointing away from the upper surface, wherein the lighting element (14) comprises a LED (28) connected to the substrate, and an optical element (16) for guiding the emitted light, whereby the optical element comprises an aperture (34) by which the lighting element is received and the optical element extends from above the emitting surface at least partially to until below the lighting element for at least partially receiving the substrate. Since the optical element extends over the whole height of the lighting element not only the whole light emitted via the emitting surface but also the whole light emitted via side faces connected to the emitting surface are guided by the optical element and used for illumination leading to an improved efficiency of the LED package.

Description

LED PACKAGE

FIELD OF THE INVENTION

The invention relates to the field of LED packages, which may be used in applications where well defined light beams are required for instance motor vehicle lamps to provide light by means of at least one light emitting diode (LED) arranged on a substrate.

BACKGROUND OF THE INVENTION

From US 6,476,551 BI a LED package is known, which comprises an array of several lighting elements, which comprise a LED each. Each lighting element is connected to an upper surface of a substrate and comprises an emitting surface pointing away from the upper surface. An optical element comprising an opening is placed on the emitting surface such that emitted light from the lighting element passing the opening is guided by the optical element and light from the lighting element not passing the opening is reflected in order to prevent scattered light.

It is a disadvantage of such kind of a LED package that the amount of used light in comparison to the energy consumption of the LED package is low. This results in a low efficiency of the LED package.

SUMMARY OF THE INVENTION It is an object of the invention to provide a LED package comprising an improved efficiency.

This object is achieved by a LED package for use in a lamp, particularly headlight or taillight of a motor vehicle, comprising a substrate comprising an upper surface, at least one lighting element for emitting light via an emitting surface pointing away from the upper surface, wherein the lighting element comprises a LED connected to the substrate, and an optical element for guiding the emitted light, whereby the optical element comprises an aperture by which the lighting element is received and the optical element extends from above the emitting surface at least partially to until below the lighting element for at least partially receiving the substrate. Particularly the optical element extends circumferential below the level of the upper surface.

Since the lighting element is received by the optical element the whole amount of light emitted via the emitting surface can be used for illumination. Since the optical element extends over the whole height of the lighting element not only the whole light emitted via the emitting surface but also the whole light emitted via side faces connected to the emitting surface are guided by the optical element and used for illumination. Particularly the optical element, which may be a solid transparent volume using total internal reflection or an open reflector with reflective faces, extends at all sides of the lighting element preferably circumferential below the level of the upper surface of the substrate. Due to the increased amount of used light emitted from the lighting element the efficiency of the LED package is improved, while the high luminance of the light source is maintained. Since the optical element protrudes until below the lighting element, particularly below the level of the upper surface of the substrate where a mounting location of the lighting element is provided, an inside surface of the optical element forming the aperture may be arranged close to side faces of the substrate. The mechanical stability as well as the accuracy of the positioning of the optical element with respect to the lighting element(s) may be improved. The optical element may be mounted directly on the substrate. Particularly it is possible to glue the optical element via the inside surfaces to the side faces of the substrate so that the used glue may not affect the lighting element and the optical performance of the optical element. Further it is possible to position the optical element free-floating around the lighting element, this means without a direct connection to the substrate. This would prevent mechanical forces on the substrate via the optical element.

On the one hand it is preferred that the optical element covers as much as possible of the side faces of the substrate in order to improve mechanical stability. On the other hand it is preferred that the optical element covers as less as possible of the side faces of the substrate in order to provide a small outlet surface. Since the outside surfaces of the optical element provides reflection faces for the emitted light, the design of the optical element is based on the desired optical function, wherein a small outlet surface is desired to provide a high light intensity for the light emitted via the outlet surface. In order to provide a good mechanical stability and a good light performance at the same time it is preferred that the optical element covers the substrate over a height of 20μm - 300μm, preferably 50μm - 200μm and most preferred 80μm - 120μm.

Preferably the upper surface of the substrate comprises a lighting area, in which the at least one lighting element is arranged, and a connector area for providing lines for connecting the lighting element to an electric source, wherein the lighting area protrudes with respect to the connector area. Due to the protruding lighting area with respect to the remaining upper surface of the substrate the optical element may cover the lighting element over the whole circumference. Further the optical element may protrude over all sides below the level of the lighting area and thus below the level of the lighting element, wherein it is not necessary to protrude below the level of the connector area.

Further it is possible that the substrate comprises a lower surface pointing away from the upper surface and the upper surface comprises a lighting area, in which the lighting element is arranged, and a connector area for providing lines for connecting the lighting element to an electric source, wherein the distance of the lighting area to the lower surface is higher than the distance of the connector area to the lower surface and the distance between the lighting area and the connector area is of particularly 20μm - 500μm, preferably 50μm - 350μm and most preferred lOOμm - 200μm. Preferably the surfaces of the lighting area and the connector area are mainly parallel to the lower surface. The manufacture of the substrate is facilitated and may be performed by providing several layers connected to each other, wherein the different layers provide the different levels of the lighting area and the connector area.

Preferably between the emitting surface and at least one, particularly two, preferably three and most preferred four edges provided by the upper surface and/or an adjacent arranged further lighting element a rim is provided, wherein the rim comprises a distance between the light emitting surface and the edges of 5μm - lOOμm, particularly lOμm - 70μm, preferably 15μm - 50μm and most preferred 20μm - 30μm. The inside surface of the optical element may be arranged very close to the lighting element reducing a loss of light and maintaining high luminance, wherein the rim is broad enough to manufacture the substrate by cutting a major substrate into dies without affecting the lighting elements.

Particularly between the optical element and the substrate a clearance fit is provided, wherein the clearance fit comprises a clearance gap of Oμm - lOOμm, particularly Oμm - 50μm, preferably Oμm - 20μm and most preferred Oμm - 5μm. Due to the clearance fit the optical element can be easily slid onto the substrate, wherein a good mechanical stability is provided at low manufacturing costs at the same time.

Preferably a plurality of lighting elements arranged in a regular pattern, particularly in a line and/or in columns and lines, are provided, wherein the pattern of lighting elements are received by the aperture of the optical element. This regular array of lighting elements can be easily manufactured for example by automatically arranging the lighting element onto the substrate. Moreover a single optical element is sufficient to receive the plurality of lighting elements. Particularly adjacent lighting elements comprise a distance to each other of 5μm - lOOμm, particularly lOμm - 70μm, preferably 15μm - 50μm and most preferred 20μm - 30μm. Due to this distance a gap is provided providing electrical insulation of the lighting element to each other, wherein the gap is small enough that significant changes of the light intensity of the light emitted via the optical element are avoided.

It is not necessary that the lighting element consists of a single LED. It is preferred that the lighting element comprises at least one LED connected to the substrate and a phosphor covering the LED, wherein the phosphor comprises the emitting surface and light emitting side faces connected to the emitting surface. Particularly the LED provides mainly blue light, wherein the phosphor provides mainly yellow light so that in sum mainly white light is provided by the lighting element. Particularly lines connected to the lighting element and fixed to the substrate are provided, wherein the lines are led away from the optical element. The lines are preferably provided in the connector area but may reach a little bit into the lighting area for providing electrical contact to the respective lighting element. At the opposite end the lines can be connected to connector lines providing electrical contact to electrical elements outside the LED package. Since the lines are led away from the optical element, the contact to the connector lines may be provided at a place, where the connection of the lines to the connector lines does not interfere with the connection of the optical element to the substrate.

The invention relates further to a lamp, particularly headlight or taillight for motor vehicles, comprising a LED package, which may be designed as previously described, connected to a housing, wherein the housing preferably comprises at least one lens arranged adjacent to the optical element. Due to the lens, which may be part of a lens system, the light emitted from the LED package may be focused as desired. Since the LED package is connected to the housing an exact positioning of the LED package with respect to housing is possible so that the lens may be arranged very accurate with respect to an outlet surface of the optical element of the LED package. Preferably the lens is arranged close to the outlet surface so that mainly all emitted light is collected by the lens. Thus it is possible to capture the maximum amount of light emitted from the LED package.

BRIEF DESCRIPTION OF THE DRAWINGS These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter. In the drawings:

Fig. 1 is a schematic perspective view of a LED package in a first embodiment,

Fig. 2 is a schematic sectional view of the LED package of Fig. 1, Fig. 3 is a schematic perspective view of a LED package in a second embodiment, Fig. 4 is a schematic sectional view of the LED package of Fig. 3, Fig. 5 is a schematic perspective view of a LED package in a third embodiment,

Fig. 6 is a schematic sectional view of the LED package of Fig. 5, Fig. 7 is a schematic perspective view of a LED package in a forth embodiment,

Fig. 8 is a schematic sectional view of the LED package of Fig. 7, Fig. 9 is a schematic perspective view of a LED package in a fifth embodiment,

Fig. 10 is a schematic sectional view of the LED package of Fig. 9, Fig. 11 is a schematic perspective view of a LED package in a sixth embodiment and Fig. 12 is a schematic sectional view of the LED package of Fig. 11.

DETAILED DESCRIPTION OF EMBODIMENTS

In a first embodiment the LED package 10 as illustrated in Fig. 1 comprises a substrate 12 with lighting elements 14, which are arranged regular in a line and totally covered by an optical element 16. On an upper surface 18 of the substrate 12 lines 20 are fixed, which are electrically connected to the lighting elements 14. Since the lighting elements 14 are arranged in a lighting area 22, which protrudes with respect to a connector area 24 of the upper surface 18, the optical element 16 is able to extend below the level of the lighting element 14 as well as below the level of the lighting area 22 over the whole circumference of the several lighting elements 14 (Fig. 2). In the in Fig. 1 and Fig. 2 illustrated embodiment the lighting area 22 and the connector area 24 are mainly parallel to a lower surface 26, wherein the distance of the lighting area 22 to the lower surface 26 is greater than the distance of the connector area 24 to the lower surface 26. The lighting element 14 comprises a LED 28 covered by a phosphor 30. The LED 28 is connected to the line 20, which reaches a little bit into the lighting area 22 in order to provide the electrical contact between the LED 28 and the line 20. The optical element 16 comprises an inner surface 32 by which an aperture 34 is formed. The lighting elements 14 are received by the aperture 34. The optical element 16 comprises reflection faces 36, which collect the light emitted by side faces of the lighting element 14 and guide it through an outlet surface 38 pointing in the same direction like an emitting surface 40 of the lighting element 14. In a second embodiment the connector area 24 of the LED package 10 as illustrated in Fig. 3 and Fig. 4 is formed as a groove. This means that an end part 42 of the substrate 12 is provided, which may provide a further function like fastening the substrate 12 to a housing of a lamp. A surface 44 of the end part 42 may comprise the same level like the lighting area 22. Depending on the function of the end part 42 the design of the end part 42 and/or the level of the surface 44 may vary.

In a third embodiment of the LED package 10 as illustrated in Fig. 5 and Fig. 6 the substrate 12 comprises a ramp like intermediate part 46, which is arranged between the lighting area 22 and the connector area 24 connecting them. Due to the ramp like design of the intermediate part 46 a vertical arrangement of a part of the lines 20 is prevented. This facilitates the providing of the lines 20 and the fixing of the lines 20 to the substrate. The aperture 34 of the optical element may be adapted to the contour of the intermediate part 46 such that a collision of the optical element 16 with the intermediate part 46 during assembling is prevented.

In a forth embodiment of the LED package 10 as illustrated in Fig. 7 and Fig. 8 the lighting area 22 is arranged angled with respect to the lower surface 26 of the substrate 12. The manufacture of the substrate 12 is facilitated, since only a part of a cuboid like substrate has to be cut away. In the illustrated embodiment only at side faces 48 of the substrate 12 the optical element 16 extends below the lighting element 14 and below the level of the lighting area 22. In a fifth embodiment of the LED package 10 as illustrated in Fig. 9 and

Fig. 10 the lines 20 are partially led through the substrate 12 in the protruding lighting area 22. By providing vias in the substrate in the lighting area 22 a good contact between the LED 28 and the lines 20 may be provided.

In a sixth embodiment of the LED package 10 as illustrated in Fig. 11 and Fig. 12 the protruded arrangement of the lighting element 14 with respect to the substrate 12 is provided by the lines 20, which each comprises a protruding head 50 arranged under the lighting element 14. In this embodiment it is not necessary to provide the lighting area 22 and the connector area 24 on different levels.

While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the invention is not limited to the disclosed embodiments.

For example, it is possible to operate the invention in an embodiment wherein the substrate 12 comprises an additional end part 42 and/or a ramp like intermediate part 46 and/or an angled lighting area 22 and/or vias for connecting the lighting element 14 through the substrate 12 with the lines 20 and/or lines 20 comprising an protruding head 50. Although several features of the invention are described in different embodiment for purpose of clarity it is clear that all or a part of the described features may be combined into the same embodiment. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measured cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope.

Claims

CLAIMS:

1. LED package for use in a lamp comprising: a substrate (12) comprising an upper surface (18), at least one lighting element (14) for emitting light via an emitting surface (40) pointing away from the upper surface (18), wherein the lighting element (14) comprises a LED (28) connected to the substrate (12), and an optical element (16) for guiding the emitted light, whereby the optical element (16) comprises an aperture (34) by which the lighting element (14) is received and the optical element (16) extends from above the emitting surface (40) at least partially to until below the lighting element (14) for at least partially receiving the substrate (12).

2. LED package according to claim 1 wherein the optical element (16) extends circumferential below the level of the upper surface (18).

3. LED package according to claim 1 wherein the optical element (16) covers the substrate (12) over a height of 20μm - 300μm, preferably 50μm - 200μm and most preferred 80μm - 120μm.

4. LED package according to claim 1 wherein the upper surface (18) comprises a lighting area (22), in which the lighting element (14) is arranged, and a connector area (24) for providing lines (20) for connecting the lighting element (14) to an electric source, wherein the lighting area (22) protrudes with respect to the connector area (24).

5. LED package according to claim 1 wherein the substrate (12) comprises a lower surface (26) pointing away from the upper surface (18) and the upper surface (18) comprises a lighting area (22), in which the lighting element (14) is arranged, and a connector area (24) for providing lines (20) for connecting the lighting element (14) to an electric source, wherein the distance of the lighting area (22) to the lower surface (26) is higher than the distance of the connector area (24) to the lower surface (26) and the distance between the lighting area (22) and the connector area (24) is of particularly 20μm - 500μm, preferably 50μm - 350μm and most preferred lOOμm - 200μm.

6. LED package according to claim 1 wherein between the emitting surface

(40) and at least one, particularly two, preferably three and most preferred four edges provided by the upper surface (18) and/or an adjacent arranged further lighting element (14) a rim is provided, wherein the rim comprises a distance between the light emitting surface (40) and the edges of 5μm - lOOμm, particularly lOμm - 70μm, preferably 15μm - 50μm and most preferred 20μm - 30μm.

7. LED package according to claim 1 wherein between the optical element (16) and the substrate (12) a clearance fit is provided, wherein the clearance fit comprises a clearance gap of Oμm - lOOμm, particularly Oμm - 50μm, preferably Oμm - 20μm and most preferred Oμm - 5μm.

8. LED package according to claim 1 wherein a plurality of lighting elements (14) arranged in a regular pattern, particularly in a line and/or in columns and lines, are provided, wherein the pattern of lighting elements (14) are received by the aperture (34) of the optical element (16).

9. LED package according to claim 1 wherein lines (20) connected to the lighting element (14) and fixed to the substrate (12) are provided, wherein the lines (20) are led away from the optical element (16).

10. Lamp, particularly headlight or taillight for motor vehicles, comprising a

LED package (10) according to claim 1 connected to a housing, wherein the housing comprises at least one lens arranged adjacent to the optical element (16).