Technical Field

This disclosure is directed to lighting modules, lighting devices and to luminaires comprising the modules and/or the lighting devices.

Background

A lighting module is, for example, disclosed in US 7,810,982. The lighting module of US 7,810,982 comprises a structured film on the light guide for diffusing the light.

It could be useful, however, to provide a lighting module and a lighting device emitting a collimated light beam with limited boundaries. Further, a thin luminaire is desired.

Summary

I provide a lighting module including a light guide having a light-emitting front side and a backside opposite to the front side, a light-emitting diode arranged at a lateral face of the light guide such that light of the light-emitting diode is coupled in the light guide, wherein the backside of the light guide has a structure according to a regular pattern, the structure directing incident light of the light-emitting diode to the front side of the light guide in a collimated manner.

I also provide a light device including at least two lighting modules, the lighting modules being arranged such that the light-emitting front sides of the light guides are arranged parallel next to each other.

I further provide a luminaire including the lighting module.

I still further provide a luminaire including the light device.

Brief Description of the Drawings

Figs. 1 A and 2A show schematic views of a lighting module.

Figs. IB and 1C show the regular pattern of the lighting module according to Figs. 1A and 2A.

Figs. 2B to 2C show schematic diagrams of the light spot emitted by the lighting module according to two different examples. Figs. 3 to 5 each show a schematic sectional view of a lighting module according to a further example.

Fig. 6 shows a schematic perspective view of the light guide of the lighting module of

Fig. 5.

Fig. 7 shows a schematic perspective view of a lighting module according to a further example.

Fig. 8 shows a plan view of a lighting device.

Fig. 9 shows a schematic perspective view of a luminaire.

List of reference numbers

1 lighting module

2 light guide

3 front side

4 backside

5 light emitting diode

6, 6 ^* lateral face

7 structure

8 regular pattern

81 pattern element

9 depression

10 protrusion

11 circularily shaped area

a depth of depression

b distance between directly adjacent protrusions

F focal point

n Normal

12 secondary optic

13 light entrance surface

14 lens element

15 printed circuit board

16 heat sink

C center axis Detailed Description

It will be appreciated that the following description is intended to refer to specific examples of structure selected for illustration in the drawings and is not intended to define or limit the disclosure, other than in the appended claims.

Our lighting modules comprise:

a light guide having a light-emitting front side and a backside opposite to the front side,

a light-emitting diode arranged at a lateral face of the light guide such that light of the light-emitting diode is coupled in the light guide, wherein

the backside of the light guide has a structure according to a regular pattern which directs incident light of the light-emitting diode to the front side of the light guide in a collimated manner.

The incident light may be in the form of a cone having a rotational axis running substantially parallel to the front side or the backside of the light guide. In this context, the term "substantially parallel" means that the rotational axis is as parallel as possible taking manufacturing tolerances into account.

Preferably, the light of the cone runs trough the light guide without being disturbed until a part of the light of the cone impinges on the structured backside of the light guide. The structure on the backside of the light guide redirects impinging light of the cone to the front side of the light guide. Particularly, the light runs substantially parallel to a normal of the front side of the light guide after being redirected by the structure. In this context, the term "substantially parallel" means that the light is as parallel as possible taking manufacturing tolerances into account.

Particularly preferably, the light of the light-emitting diode is coupled in the light guide such that the light forms a cone having an axis of rotation, the axis of rotation running substantially parallel to the light-emitting front side of the light guide and the structure turns impinging light about an angle of 85° to 95° to the front side, wherein the limits are included.

Preferably, the light is collimated such that the light redirected to the front side runs substantially parallel to a normal of the front side of the light guide and further such that the light spot emitted by the lighting module has defined boundaries. Preferably, 50% of the light emitted from the lighting module is contained by a virtual cone having an angle of aperture of 18°. Preferably, the light spot emitted by the light module has a mostly circular Gaussian beam pattern.

In one example of a light module, the structure on the backside of the light guide is formed by alternating protrusions and depressions in the light guide. Preferably the depth of the depressions is 0.1 mm to 1.5 mm less than the thickness of the light guide, inclusive. The distance between the tips of two directly adjacent protrusions is preferably 0.5 mm to 5 mm, inclusive. Particularly preferably, the distance between the tips of two directly adjacent protrusions is 1 mm.

For example, the regular pattern can be a ring pattern. The light-emitting diode is preferably positioned in a focal point of the ring pattern. Consequently, the focal point of the ring pattern is preferably arranged at a lateral face of the light guide. In particular, the regular pattern can comprise a plurality of concentrically arranged rings of different diameters. Preferably, the rings of the ring pattern can be parabolic, spherical or aspheric. For example, the regular pattern can be formed by alternating ring shaped protrusions and depressions in the backside of the light guide.

Our lighting modules have the advantage that their thicknesses can be very low. In particular, since the light-emitting diode, which works as a light source in the light module, is positioned at the lateral face of the light guide, a lighting module with a low thickness can be realized.

Particularly preferably, the light guide has a thickness of 4 mm to 5 mm, inclusive. A light guide with such a low thickness further contributes to a thin lighting module.

A secondary optic may be arranged over the front side of the light guide such that the light emitted from the front side of the light guide passes through the secondary optic. For example, the secondary optic has a light entrance surface arranged substantially parallel to the front side of the light guide. Preferably, the light entrance surface of the secondary optic has at least the same dimension as the front side of the light guide.

For example. _! the secondary optic may be a lens array, a diffuser sheet or an optical plate. A secondary optic can further influence the radiation characteristic of the lighting module in a desired manner. For example, the secondary optic can contribute to the homogeneity of the light intensity emitted by the lighting module. Alternatively, the secondary optic can achieve a radiation characteristic which varies from a uniform radiation characteristic in a defined manner. For example, the secondary optic can lead to a higher intensity of the light in the outer regions of the light spot and to a lower intensity in the center of the light spot.

The thickness of the light guide may become thinner towards the lateral face opposite the light-emitting diode. In other words, the light guide may be formed with a decreasing thickness towards the lateral face of the light guide, the lateral face being arranged opposite the lateral face provided with the light-emitting diode. Advantageously, the lateral face opposite the lateral face provided with the light-emitting diode is free of a light-emitting diode in this example of the lighting module.

The regular pattern may be composed of different pattern elements. For example, these pattern elements may be identical or mirror-inverted to each other. Preferably, the pattern elements are arranged symmetrically to an axis of symmetry of the backside of the light guide or to a point of symmetry of the backside of the light guide.

For example, one pattern element can be formed by concentric rings having different diameters and the light guide comprises a plurality of these pattern elements. Further, one half of the pattern elements is mirror-inverted to the other half of the pattern elements and the pattern elements are arranged symmetrically to the center axis of the light guide. Alternatively, the pattern elements can be arranged symmetrically to the center point of the light guide.

A further light-emitting diode in the lighting module may be arranged on a lateral face of the light guide, the lateral face with the further light-emitting diode being arranged opposite to the lateral face with the other light-emitting diode.

Preferably, the lighting module comprises not more than two light-emitting diodes as light sources.

The depth of the protrusion may be, within manufacturing tolerances, equal over the whole backside of the lighting module.

Alternatively, the depth of the protrusions can vary with the location on the backside in a coordinated manner. For example, the depth of the protrusions can increase with distance from the light-emitting diode to the center of the backside if two light-emitting diodes are arranged at opposite lateral faces of the light guide. If only one lateral face is provided with a light-emitting diode, while the opposite lateral face of the light guide is free of a light-emitting diode, the depth of the protrusions preferably increases with the distance from the light-emitting diode over the entire length of the backside. The light-emitting diode may be mounted on a printed circuit board. Further, the printed circuit board with the light-emitting diode may be arranged on a heat sink. Preferably, the printed circuit board is arranged in direct contact with the heat sink. Since the light-emitting diodes are arranged laterally of the light guide, the heat sink and further possible package elements of the light-emitting diode do not increase the thickness of the lighting module advantageously.

Further, it is also possible that the light emitting diode is arranged on a MID-carrier (molded interconnect device) instead of a printed circuit board. An aluminum board can be used as a heat sink.

Further, at least two lighting modules can be comprised by a lighting device. The lighting modules are preferably arranged such that the light-emitting front sides of the light guides are arranged parallel next to each other to achieve a larger light-emitting area of the lighting device than of a lighting module. It is in particular possible to achieve a larger light- emitting area of the lighting device without increasing the thickness of the lighting device.

The lighting module is particularly suited to be part of a luminaire, in particular, of the light-emitting head of the luminaire. The lighting device is also particularly suited to be part of a luminaire, in particular, of the light-emitting head of the luminaire.

The luminaire can, for example, be a spotlight or a task light. In particular, a spotlight or a task light emits light in the form of a spot having defined boundaries as preferably produced by the present light-emitting module.

Particularly preferably, the luminaire has a thickness of 5 mm to 10 mm, inclusive. The lighting module and the lighting device described above are particularly suited to be used in a luminaire having a low thickness.

Selected, preferred examples of our lighting modules, lighting devices and luminaires are described in the following in connection with the Figures.

Equal or similar elements as well as elements of equal function are designated with the same reference signs in the figures. The figures and the proportions of the elements shown in the figures are not regarded as being shown to scale. Rather, single elements, in particular layers, can be shown exaggerated in magnitude for the sake of better presentation.

The lighting module according to the example in Figs. 1 and 2 comprises a light guide

2, which has a light-emitting front side 3 and a backside 4 arranged opposite to the light- emitting front side 3. Further, the lighting module 1 comprises a light-emitting diode 5 arranged at a lateral face 6 of the light guide 2 such that light of the light-emitting diode 5 is coupled laterally in the light guide 2. The backside 4 of the light guide 2 has a structure 7 according to a regular pattern. The structure 7 directs incident light of the light-emitting diode 5 to the front side 3 of the light guide 2 in a collimated manner.

The regular pattern 8 of the structure 7 on the backside 4 of the light guide 1 is a ring pattern (Fig. IB). The structure 7 is formed by a plurality of substantially concentrically arranged spherical shaped alternating depressions 9 and protrusions 10 as can be seen in the depth profile of Fig. 1C along the line BB' in Fig. IB. A circularly shaped area 11 of the backside 4 of the light guide 2 is substantially free of depressions 9 and protrusions 10. The circularly shaped area 11 is arranged in the center of the ring pattern.

A depth d of the depressions is preferably 0.1 mm to 1.5 mm less than the thickness of the light guide, inclusive. The tips of two directly adjacent protrusions have preferably a distance of 0.5 mm to 5 mm, inclusive.

The light-emitting diode 5 is further presently arranged such that is located in a focal point F of the regular pattern.

As can be seen in the schematic sectional view of the lighting module shown in Fig. 2A, the light of the light-emitting diode 5 forms a light cone which is laterally coupled in the light guide 2 via the lateral face 6. The light cone runs laterally through the light guide 2, wherein an axis of rotation of the light cone is substantially parallel to a front side 3 of the light guide 2.

In a first area of the light guide 2 along the front side 3, the light cone passes through the light guide 2 substantially without disturbance. After a certain distance from the light- emitting diode 5 along the front side 3, outer parts of the light cone impinge on the structured backside 4 of the light guide 2. The structure 7 of the backside 4 of the light guide 2 redirects the beams of the impinging light to the front side 3 of the light guide 2. With increasing distance from the light-emitting diode 5 along the front side 3 of the light guide 2 an increasing part of the light of the light cone impinges on the backside 4 of the light guide 2 and is redirected to the front side 3 by the structure 7. The light is preferably redirected such that it is substantially parallel to a normal n of the front side 3 of the light guide 2.

Further, as can be seen in Fig. 2 A, the thickness of the light guide 2 starts to decrease at a certain distance from the light-emitting diode 5 along the front side 3 of the light guide 2. In this instance, there is only one light-emitting diode 5 provided at one lateral face 6 of the light guide 2. In particular, the lateral face 6' of the light guide 2, which is opposite the light- emitting diode 5, is very thin due to the decrease in thickness and is consequently free of a light-emitting diode 5.

Fig. 2B shows a schematic view of a light spot emitted by the lighting module of Figs. 1A to 1C. As can be seen in the intensity profile I(x) along the axis AA' of the light spot, the spot has definite boundaries and a Gaussian profile.

In contrast to the lighting module 1 according to the examples of Figs. 1 A to 2 A, the lighting module 1 according to the example of Fig. 3 further comprises a lens array as secondary optic 12. The lens array has a light entrance surface 13, which is arranged parallel to the light-emitting front side 3 of the light guide 2. The lens array comprises a plurality of equally formed lens elements 14. The lens elements 14 in this instance have a collimating function for light running through the lens array starting from the light entrance surface 13.

In contrast to the examples according to Figs. 1A to 3, the lighting module 1 of the example of Fig. 4 comprises two light-emitting diodes 5 arranged at opposite lateral faces 6, 6' of the light guide 2. Each light-emitting diode 5 is mounted on a printed circuit board 15 and the printed circuit board 15 is arranged in direct contact with a heat sink 16. Further, a secondary optic 12 is arranged over the front side 3 of the light guide 2. The secondary optic 12 can be an optical plate, a diffuser sheet or a lens array, for example. The backside 4 of the light guide 2 comprises a structure 7 which redirects impinging light from the light-emitting diodes 5 to the front side 3 of the light guide 2.

The structure 7 is formed by ring-shaped protrusions 10 and depressions 9. In this instance, the depth d of the depressions 9 becomes deeper with increasing distance from the light-emitting diodes 5 towards the center of the light guide 2.

The lighting module 1 of Figs. 5 and 6 also comprises, as does the lighting module 1 of Fig. 4, two light-emitting diodes 5 arranged at opposite lateral faces 6, 6' of the light guide 2.

The schematic perspective view of Fig. 6 shows the structure 7 on the backside 4 of the light guide 2 of the lighting module 1 of Fig. 5. The regular pattern 8 of the structure 7 comprises two pattern elements 81 which are mirror-inverted to each other. Each pattern element 81 comprises a plurality of spherical depressions 9 and protrusions 10 which are arranged substantially concentrically. Further, both pattern elements 81 are arranged symmetrically with respect to a center axis c of the backside 4 of the light guide 2. The light- emitting diodes 5 are each arranged within the focal point F of a pattern element 81.

The lighting module 1 according to Fig. 7 comprises a light guide 2 with a structure 7 according to a regular pattern 8. The regular pattern 8 is formed by four pattern elements 81, each pattern element 81 comprises substantially concentrically arranged depressions 9 and protrusions 10. Each pattern element 81 has a focal point F, in which a light-emitting diode 5 is positioned as a light source.

The lighting device according to Fig. 8 comprises three light modules 1 which have been already described in connection with Fig. 4. Alternatively, the lighting modules 1 can, for example, also be formed as already described in connection with Figs. 5 and 6. Preferably, the lighting device comprises a plurality of equal light modules 1.

The specific lighting modules 1 of the lighting device of Fig. 8 are arranged such that the light-emitting front sides 3 of their light guides 2 are positioned substantially parallel next to each other forming a single light-emitting surface. In such a way, a lighting device with a large light-emitting surface can be achieved.

The luminaire of Fig. 9 has a head comprising a lighting module 1 as already described in connection with Figs. 1 to 7 or a lighting device as already described in connection with Fig. 8.

This disclosure is not limited to the description of the examples. Rather, this disclosure comprises each new feature as well as each combination of features, particularly each combination of features of the appended claims, even if the feature or the combination of features itself is not explicitly recited. In particular, the lighting modules, lighting devices and luminaires described above are not limited to a ring-shaped regular pattern.