LIGHTING DEVICE

Abstract

The present invention concerns a lighting device comprising a source for generating electromagnetic radiation, and a beam shaper which is so arranged and adapted that in operation of the lighting device it spatially expands the electromagnetic radiation issuing from the source. In comparison therewith the object of the present invention is to provide such a lighting device which ensures eye safety even when the beam shaper is detached or damaged. For that purpose it is proposed according to the invention that the lighting device has a sensor which is so adapted that in operation of the lighting device it detects a state of the beam shaper, wherein the sensor and the source are so operatively connected together and adapted that if during operation of the lighting device the state of the beam shaper changes in such a way that electromagnetic radiation could issue from the lighting device without the beam shaper being in the beam path of the electromagnetic radiation the source is switched off.

Claims

1. A lighting device (9, 9′) comprising a source (7, 7′) for generating electromagnetic radiation, and a beam shaper (8) which is so arranged and adapted that in operation of the lighting device (9, 9′) it spatially expands the electromagnetic radiation issuing from the source (7, 7′), characterised in that the lighting device (9, 9′) has a sensor (11) which is so adapted that in operation of the lighting device it detects a state of the beam shaper (8), wherein the sensor (11) and the source (7, 7′) are so operatively connected together and adapted that if during operation of the lighting device (9, 9′) the state of the beam shaper (8) changes in such a way that electromagnetic radiation could issue from the lighting device (9, 9′) without the beam shaper (8) being in the beam path of the electromagnetic radiation the source (7, 7′) is switched off.

2. A lighting device (9, 9′) according to claim 1 characterised in that the sensor (11) is an electric switch which is so adapted and arranged that the switch is closed if the beam shaper (8) or a protective cap (1) for the beam shaper (8) is arranged at a position of the lighting device (9, 9′) intended for the beam shaper or the protective cap, wherein preferably the switch is electrically connected to the source (7, 7′) in such a way that in operation of the lighting device (9, 9′) a current required for generation of the electromagnetic radiation in the source (7, 7′) flows by way of the switch.

3. A lighting device (9, 9′) according to claim 1 characterised in that the lighting device (9, 9′) has a protective cap (1) having an opening (4) through which in operation of the lighting device (9, 9′) the electromagnetic radiation generated by the source (7, 7′) can issue, wherein the protective cap (1) is so adapted and arranged that it at least portion-wise surrounds the source (7, 7′) and the beam shaper (8) in such a way that the protective cap (1) limits a movement of the beam shaper (8) relative to the source (7, 7′) in such a way that in operation of the device even after a change in position of the beam shaper (8) the electromagnetic radiation emitted by the source (7, 7′) and issuing from the protective cap (1) through the opening is completely expanded at the beam shaper (8).

4. A lighting device (9, 9′) according to claim 3 characterised in that the protective cap (1) has an electrically conducting portion and the sensor has the protective cap (1) and two electric contacts (5) connected to the control means (10), wherein the contacts (5) and the electrically conducting portion of the protective cap (1) form a switch, by way of which a current flows in operation of the lighting device (9, 9′) if the protective cap (1) is arranged at the position intended for same.

5. A lighting device (9, 9′) according to claim 3 characterised in that the protective cap (1) is made from a preferably solderable electrically conductive material, preferably metal and particularly preferably brass.

6. A lighting device (9, 9′) according to claim 4 claims characterised in that the electrically conducting portion of the protective cap (1) is soldered to the contacts (5).

7. A lighting device (9, 9′) according to claim 4 characterised in that the lighting device (9, 9′) has a circuit board (6) on which the source (7, 7′) and the contacts (5) of the sensor are arranged.

8. A lighting device (9, 9′) according to claim 1 characterised in that the lighting device (9, 9′) has a control means (10) which is electrically connected to the source (7, 7′) and which is operatively connected to the sensor in such a way that a current required for generation of the electromagnetic radiation in the source (7, 7′) does not flow by way of the sensor, wherein the control means (10) is so adapted that in operation of the lighting device (9, 9′) it prevents electromagnetic radiation from issuing from the lighting device (9, 9′) if the sensor (11) signals that the state of the lighting device (9, 9′) has changed in such a way that there is the danger that electromagnetic radiation issues from the lighting device (9, 9′) without it having been shaped at the beam shaper (8).

9. A lighting device (9, 9′) according to claim 8 characterised in that the sensor has two electric contacts (5) electrically connected to the control means (10) and an electrically conducting portion at the beam shaper (8), wherein the electrically conducting portion of the beam shaper (8) is in engagement with the electric contacts (5) in such a way that in operation of the lighting device (9, 9′) a current can flow by way of the electric contacts (5) and the electrically conducting portion.

10. A lighting device (9, 9′) according to claim 9 characterised in that the electrically conducting portion at the beam shaper (8) forms an electrically conductive path on the surface of the beam shaper (8).

11. A lighting device (9, 9′) according to claim 9 characterised in that the electrically conducting portion is applied to a plastic film which is applied to, preferably glued to, the beam shaper (8).

12. A lighting device (9, 9′) according to claim 9 characterised in that the electrically conductive portion of the beam shaper (8) comprises an electrically conducting material which is non-transparent to electromagnetic radiation, wherein the electrically conductive portion is so arranged that a part of the beam shaper (8) is uncovered so that electromagnetic radiation can pass the beam shaper (8).

13. A lighting device (9, 9′) according to claim 8 characterised in that the sensor (11) is a capacitive sensor (11) which is so adapted and arranged that it detects a positioning of the beam shaper (8) or a protective cap (1) for the beam shaper (8).

Description

[0056] Further advantages, features and possible uses of the present invention will be apparent from the description of embodiments hereinafter and accompanying Figures.

[0057] FIG. 1 shows a perspective view of a protective cap according to the invention for a lighting device,

[0058] FIG. 2 shows the protective cap of FIG. 1 in the mounted state, and

[0059] FIG. 3 shows a diagrammatic sectional view through an alternative embodiment of the lighting device according to the invention.

[0060] In the Figures identical elements are denoted by the same references.

[0061] FIG. 1 is a perspective view of a protective cap 1 according to the invention for a lighting device having a semiconductor laser and a scattering element. The protective cap 1 has four support feet 1 with which the protective cap 1 in the mounted condition is supported on contacts or contact surfaces provided for same of a circuit board. In addition the protective cap 1 has a frame element 3 connecting the support feed 2 together. The frame element has an opening 4, from which in operation of the lighting device the electromagnetic radiation generated by the semiconductor laser issues from the lighting device.

[0062] FIG. 2 shows the protective cap 1 in the mounted state on a circuit board 6. The feet 2 of the protective cap 1 are soldered to contacts 5 provided for same on the circuit board 6. In the mounted state the protective cap 1 surrounds the actual semiconductor laser 7, in the illustrated embodiment, a vertical-cavity surface-emitting laser, and a scattering element 8 arranged on the emission surface of the vertical-cavity surface-emitting laser 7. In this case the protective cap 1 is of such dimensions that it receives both the semiconductor laser 7 and also the scattering element 8 in its interior.

[0063] In the illustrated embodiment the scattering element 8 is glued to the emitting surface of the semiconductor laser 7. In this case the protective cap 1 is of such dimensions that, if the adhesive bond between the scattering element 8 and the semiconductor laser 7 fails, the scattering element 8 cannot fall out of the opening 4. In addition the frame element 3 of the protective cap 1 limits lateral movement of the scattering element 8 relative to the semiconductor laser 7 in such a way that, even upon maximum displacement of the scattering element 8, no radiation can issue from the protective cap 1 past the scattering element 8.

[0064] In other words when the protective cap 1 is fixed it ensures that electromagnetic radiation emitted by the semiconductor laser 7 is always transmitted through the scattering element before it issues from the lighting device.

[0065] In accordance with the present application the lighting device 9 embraces all elements which are to be seen in the view in FIG. 2.

[0066] In the illustrated embodiment the scattering element 8 is an etched glass pane which upon the transmission of electromagnetic radiation through the scattering element 8 causes diffuse scattering of the radiation so as to ensure eye safety in respect of the semiconductor laser 7.

[0067] In the illustrated embodiment the protective cap 1 is made from brass so that it is electrically conductive. That makes it possible to use the protective cap 1 as a constituent part of an electrical circuit, by way of which in operation of the semiconductor laser 7 the current required for the emission of the electromagnetic radiation can be taken.

[0068] Besides the protective cap 1 the switch is also formed by two of the contacts 5 on the circuit board 6. In the illustrated embodiment these are two diagonally opposite contacts 5. Those contacts 5 are electrically conductingly connected to the semiconductor laser 7 in such a way that during operation of the lighting device, an electric current flows by way of the contact surfaces 5, the protective cap 1 and through the semiconductor laser 7. The switch is then closed.

[0069] If however, for example due to a mechanical effect, the protective cap 1 comes loose from the circuit board 6, the switch is then opened. That state directly results in no current flowing through the semiconductor laser 7 so that the emission of electromagnetic radiation no longer occurs. The switch serves as an interlock for the semiconductor laser 7.

[0070] FIG. 3 shows an alternative embodiment in which the interlock according to the invention for the semiconductor laser 7′ is not implemented by a cap embracing the semiconductor laser 7′ and the scattering element 8. Rather, this embodiment involves a capacitive sensor 11 arranged in the semiconductor laser 7′ itself. This capacitive sensor comprises two capacitor electrodes 12, 13 in plate form, which are connected to the control means 10 by way of conductor paths. The capacitance of the capacitor formed by the electrodes 12, 13 depends on what material is arranged in the environment of the electrodes 12, 13.

[0071] As before the scattering element 8 comprises an etched glass, that is to say a dielectric material. If the scattering element 8 becomes detached from the semiconductor laser 7′ the capacitance of the capacitor formed by the electrodes 12, 13 changes. That change in capacitance is detected by the control means 10 and as a consequence of the change in capacitance the control means 10 switches off the semiconductor laser 7. This also effectively prevents electromagnetic radiation from issuing from the lighting device 9′ without having passed through the scattering element 8.

[0072] For the purposes of the original disclosure it is pointed out that all features as can be seen by a man skilled in the art from the present description, the drawings and the claims, even if they are described in specific terms only in connection with certain other features, can be combined both individually and also in any combinations with other of the features or groups of features disclosed here insofar as that has not been expressly excluded or technical aspects makes such combinations impossible or meaningless. A comprehensive explicit representation of all conceivable combinations of features is dispensed with here only for the sake of brevity and readability of the description.

[0073] While the invention has been described and illustrated in detail in the drawing and the preceding description that illustration and description is only by way of example and is not deemed to be a limitation on the scope of protection as defined by the claims. The invention is not limited to the disclosed embodiments.

[0074] Modifications in the described embodiments are apparent to the man skilled in the art from the drawings, the description and the accompanying claims. In the claims the word “have” does not exclude other elements or steps and the indefinite article “a” does not exclude a plurality. The mere fact that certain features are claimed in different claims does not exclude the combination thereof. References in the claims are not deemed to be a limitation on the scope of protection.

LIST OF REFERENCES

[0075] 1 protective cap [0076] 2 support feet [0077] 3 frame element [0078] 4 opening [0079] 5 contact [0080] 6 circuit board [0081] 7, 7′ semiconductor laser [0082] 7′ semiconductor laser [0083] 9, 9′ lighting device [0084] 11 capacitive sensor [0085] 12, 13 capacitor electrodes