ILLUMINANT WITH LEDs

Abstract

An illuminant with at least two LEDs mounted on mutually opposite sides of a support plate and a reflection surface formed as a concave mirror, in which concave mirror the LEDs are arranged, wherein a housing part of the illuminant made of a transparent housing material is provided, which housing part at the same time forms an in relation to the main propagation direction lateral external surface of the illuminant and supports a reflecting layer forming the reflection surface at an internal surface opposite to the external surface.

Claims

1. Illuminant, comprising a first LED and a second LED for emitting light, a planar support plate on which the LEDs are mounted, a reflection surface shaped as a concave mirror, in which concave mirror the LEDs mounted on the support plate are arranged so that in operation at least a portion of the light emitted therefrom is reflected by the reflection surface and thereby bundled with a main propagation direction, a base connection to which the LEDs are connected in an electrically operable manner for electrically contacting the illuminant from outside, wherein a direction of one surface of the support plate is aligned along the main propagation direction, and wherein the first LED is mounted on a first side of the support plate and the second LED is mounted on a second side of the support plate opposite thereto in relation to a thickness direction of the support plate, and wherein a housing part of the illuminant made of a transparent housing material is provided, which housing part at the same time forms an external surface of the illuminant, the external surface flanking the main propagation direction and supporting a reflecting layer which forms the reflection surface at an internal surface opposite to the external surface.

2. Illuminant according to claim 1, in which the housing material is glass and/or the reflecting layer is a dichroic layer.

3. Illuminant according to claim 1, in which the support plate is a circuit board with a conducting path structure, to which the LEDs are electrically conductively connected, wherein in addition to the LEDs at least parts of a driver electronics for operating the LEDs are also mounted on the circuit board and are electrically conductively connected to the conducting path structure.

4. Illuminant according to claim 1, in which the support plate comprises a metal layer with an area of at least 20 mm.sup.2 for heat spreading.

5. Illuminant according to claim 1, comprising a cooling element, which is arranged in direct thermal contact with the support plate and the housing part, respectively, between these two and has a thermal resistance of at most 45 K/W, taking contact resistances into account.

6. Illuminant according to claim 5, in which the cooling element contacts the first side and the second side of the support plate with a spring respectively and the support plate is held between the springs, preferably exclusively in a friction-locked manner.

7. Illuminant according to claim 5, in which the cooling element is composed of at least two parts, which cooling element parts together enclose the support plate in relation to a revolution around the main propagation direction.

8. Illuminant according to claim 5, in which an in relation to the main propagation direction rear portion of the housing part opposite to a portion of the housing part, supporting the reflecting layer, circumferentially confines a cavity, into which the cooling element is inserted and preferably held therein in a friction-locked manner.

9. Illuminant according to claim 1, in which an optical body of a transparent optical body material is placed at a front end of the support plate in relation to the main propagation direction, at least a portion of the light emitted from the LEDs permeating the optical body without reflection.

10. Illuminant according to claim 9, in which the optical body acts as a converging lens and diffracts at least a portion of the light permeating the optical body into a target solid angle region, which target solid angle region includes all directions tilted with respect to the main propagation direction by not more than 45.

11. Illuminant according to claim 9, in which the optical body comprises a light mixing means, preferably a micro lens arrangement.

12. Illuminant according to one of the claim 9, in which the optical body is interlocked with the support plate and/or the cooling element.

13. Illuminant according to claim 12, in which the optical body in its interlocked fit presses the springs of the cooling element in their abutment against the support plate.

14. Illuminant according to claim 1, comprising a transverse reflector placed at the support plate and extending transversely to the main propagation direction.

15. Method for producing an illuminant according to claim 8, in which at first the cooling element is mounted to the support plate and then the cooling element is inserted into the cavity together with the support plate.

Description

SHORT DESCRIPTION OF THE DRAWINGS

[0051] Hereafter the invention is explained in further detail on the basis of embodiments, wherein the individual features can also be relevant for the invention in another combination within the scope of the sub-claims, and furthermore it is also not distinguished in detail between the different claim categories.

[0052] In detail,

[0053] FIG. 1a shows a first illuminant according to the invention in an oblique front view;

[0054] FIG. 1b shows the illuminant according to FIG. 1a additionally with an optical body covering the support plate and LEDs;

[0055] FIG. 1c shows a schematic cross section through the illuminant according to FIG. 1b;

[0056] FIG. 2 shows another illuminant according to the invention differing from those according to FIGS. 1b, c in the configuration of the optical body;

[0057] FIG. 3a shows an LED-fitted support plate with the cooling element attached thereto as a light source of the illuminant according to FIGS. 1 and 2;

[0058] FIG. 3b shows a part of the cooling element according to FIG. 3a;

[0059] FIG. 4 shows an optical body for an illuminant according to the FIGS. 1, 2 in an oblique rear view;

[0060] FIG. 5 shows a cross section through an illuminant with an arrangement of support plate and cooling element according to FIG. 3a and an optical body according to FIG. 4.

PREFERRED CONFIGURATION OF THE INVENTION

[0061] FIG. 1a shows a first illuminant 1 according to the invention with LEDs 3 mounted on a support plate 2. The support plate 2 is configured as a circuit board with a conducting path structure (not illustrated) by which the LEDs 3 are connected to a driver electronics and a base connection (c.f. FIG. 1c). The support plate 2 is fitted with LEDs 3a on a first side and with LEDs 3b (not visible) on the opposite side, namely with two LEDs 3 each on both sides.

[0062] The LEDs 3 are arranged in a concave mirror formed by a reflection surface 4; therefore a portion of the light emitted by the LEDs 3 is directed over the reflection surface 4 and thereby bundled. The reflection surface 4 is faceted, namely subdivided into a plurality of facets; thereby each of the facets for itself is respectively slightly convexly bulged, thus out of the remaining reflection surface 4.

[0063] The reflection surface 4 is formed by a dichroic reflecting layer applied to a provided housing part 5 made of glass. At the same time this housing part 5 forms an external surface 6 of the illuminant 1. In a side view to the illuminant 1 the dichroic reflecting layer is visible through the glass; a less portion of the light which is incident to the reflection surface 4, however not reflected on it, but transmitted shimmers through. The reflected and thereby bundled portion of the light having then a main propagation direction 7 can be used for spot lighting.

[0064] On both sides springs 8a, b of a cooling element placed at the support plate 2 abut against the support plate 2, c.f. also in detail the FIGS. 3a, b. Furthermore in the oblique view according to FIG. 1a, a transverse reflector 9 placed at the support plate 2 can be seen which on the one hand covers a cavity (c.f. FIG. 1c) and on the other reflects a portion of the light forward emitted by the LEDs 3 backwards.

[0065] FIG. 1b shows the illuminant 1 according to FIG. 1a in addition with an optical body 10 placed at the support plate 2. Generally, an illuminant 1 is also conceivable without such an optical body 10, for example if an opaque covering disc is placed at the front edge of the reflection surface (not shown in the Figures). However, an optical body 10 is preferably provided, and the FIGS. 1a, b can insofar illustrate different assembling steps.

[0066] FIG. 1c shows a schematic cross section through the illuminant 1 according to FIG. 1b, wherein the sectional plane includes the optical axis of the reflection surface 4. A first portion of the light emitted by the LEDs 3 is incident to the reflection surface 4 and bundled along the main propagation direction 7. A second portion of the light passing the reflection surface 4 without reflection permeates the optical body 10 and is bundled by that. The optical body 10 acts as a convex or converging lens, namely diffracts the light permeating it into a target solid angle region including all directions deviating from the main propagation direction 7 by not more than 45. More light is proportionally bundled with the optical body 10.

[0067] Another, not-illustrated portion of the light emitted by the LEDs 3 is emitted backwards, thus to the left in FIG. 1c, and is incident to the transverse reflector 9. The transverse reflector 9 then reflects it forwards, and at least a portion of this light also permeates the optical body 10. Furthermore the transverse reflector 9 also covers the cavity 11 disposed in a rear portion 12b of the housing part 5. The rear portion 12b adjoins the front portion 12a of the housing part 5, supporting the reflecting layer 13, backwards.

[0068] Together with the LEDs 3, driver electronics 14 are also arranged on the support plate 2, namely on a rear portion of the support plate 2. This rear portion of the support plate 2 is placed in the cavity 11 and covered forward by the transverse reflector 9. The conducting path structure (not illustrated) of the support plate 2 configured as a circuit board is connected to the base connection 16, in this case a GU 10 base, by means of soldered wires 15.

[0069] FIG. 2 shows another illuminant 1 according to the invention differing from that according to FIG. 1b by the optical body placed at the support plate 2. Although in the present case the optical body 10 in total is also formed as a planar convex lens, however a plurality of micro lenses 21 is formed into the light emitting surface 20 as light mixing means. The light permeating the optical body 10 of the illuminant 1 according to FIG. 2 is thus subdivided into a plurality of sub-beam bundles, which are respectively widened to some extent and thereby superimposed. In consequence a light mixing occurs. The micro lenses 21 are distributed over the light emitting surface 20 according to a Fibonacci pattern.

[0070] FIG. 3a shows the support plate 2 with the LEDs 3, which is then inserted into the housing part 5, in further details. Here in particular, a cooling element 30 is perceivable, at which the springs 8a, b abutting against the support plate 2 on both sides are formed. The cooling element 30 is composed of two cooling element parts 30a, b, which together enclose the support plate 2.

[0071] The two cooling element parts 30a, b are a punched part each; FIG. 3b illustrates one of them viewed singly. The base form is punched out of a metal sheet and then transformed into the illustrated three-dimensional shape by bending. The two cooling element parts 30a, b are assembled around the support plate 2 and then abut against one of the two sides of the support plate 2 by means of two springs 8a, b each. As an alternative to a mere abutment, for example a self-adhesive intermediate material (TIM) for thermal connection can also be provided.

[0072] The springs 8a, b form a front portion of the cooling element 30; its rear portion shaped as a hollow cylinder is then inserted into the cavity 11 in the housing part 5 together with the support plate 2 (c.f. FIG. 1c for illustration). The hollow-cylindrical portion of the cooling element 30 has a small oversize and is thus then held in the cavity 11 in a friction-locked manner. The exterior wall of the hollow-cylindrical portion extensively abuts against an internal wall of the housing part 5 confining the cavity 11, which ensures a good thermal connection.

[0073] FIG. 4 shows an optical body 10 seen from below, thus seen from behind, facing the light ingress surface 40. At this light ingress surface 40 two bars 41 extending parallel to each other across the light ingress surface 40 are formed out of the optical body material (here polycarbonate). Two recesses 42 serving for interlocking the optical body 10 to the support plate 2 can furthermore be seen at the edge side of the light ingress surface 40. For this purpose the side parts of the optical body 10, in which one of the recesses 42 each is provided, are separated from the remaining optical body 10 partially by a respective slot. Thus, the side parts can temporarily flex outwards when the optical body 10 is slid on, before the optical body 10 clicks into its interlocked fit.

[0074] The cross section according to FIG. 5 including the optical axis of the reflector illustrates the optical body 10 placed at the support plate 2 (together with the cooling element, not visible in cross section) in its interlocked fit. At two edge surfaces 50a, b of the support plate 2, extending along the main propagation direction 7 one projection 51a, b each is provided at the front end engaging the respectively associated recess 42a, b in the optical body 10. In this interlocked fit the bars 41 then also press the springs 8a, 8b of the cooling element 30 onto the support plate 2 (cf. the FIGS. 3a and 4 in overall view).

[0075] Furthermore in FIG. 5 the assembly of the transverse reflector 9 to the support plate 2 can be seen, for this purpose the latter comprises a groove 52a, b at both its edge surfaces 50a, b, respectively. The transverse reflector 9 is slotted corresponding to the width of the support plate 2 remaining in consideration of the grooves 52a, b, wherein this slot is centrally placed in the transverse reflector 9. One of the bars adjoining the slot and remaining at the edge of the transverse reflector 9 is disconnected, so that the transverse reflector 9 can be flipped open and placed onto the support plate 2. In FIG. 5 the bars of the transverse reflector 9 then resting in the grooves 52a, b can be seen.

[0076] Finally, in FIG. 5 a covering disc 55 closing the concave mirror formed by the reflection surface can also be seen. In the present case it is clearly, thus transparently, configured.