DE102012223857A1 - Laser activated remote phosphorus lighting device e.g. light, for use as e.g. headlight, has return beam mirror arranged apart from main direction of secondary light and arranged such that primary light portion is guided on converter region - Google Patents

Abstract

The device (11) has a converter region (13) diagonally illuminated by a semiconductor light source e.g. laser (12) and LED. The converter region is attached on an opaque support (16). A decoupling optic unit (17) is provided downstream to the converter region and arranged in a main radiation direction (H2) of a secondary light (S) i.e. yellow secondary light. A return beam mirror (18) is arranged apart from the main direction of the secondary light. The mirror is arranged such that a primary light portion (F) reflected by the converter region is guided on the converter region.

Description

The invention relates to a remote phosphor lighting device, comprising a semiconductor light source, a converter area which can be irradiated by the semiconductor light source, which converter area is applied to an opaque base, and a coupling area downstream of the converter area, which is arranged in a main emission direction of a secondary light generated by the converter area. The invention is particularly applicable to vehicle lighting devices, in particular headlights, or as a light source for projection systems (video, data, film).

It is known for light emitting devices the LARP ("Laser Activated Remote Phosphor") method, in which a laser irradiates primary light onto a converter area. The converter section has phosphor (called "phosphor") which partially converts or converts the primary light into light ("secondary light") of longer wavelength. If the laser radiation hits an e.g. From the front of the converter area, penetrate from there into the phosphor, where it is partially converted by the phosphor. If the converter area is associated with e.g. on its back on a non-transparent heat sink, the secondary light is radiated from the front again ("reflective arrangement"). A main emission direction of the converted secondary light out of the phosphor is oriented perpendicular to the surface thereof and generally has a Lambertian emission characteristic with maximum emission parallel to the normal of the phosphor surface. In this main emission direction also a part of unconverted, e.g. emitted from the converter area diffusely reflected, primary light. Thus, a mixed light of primary light and secondary light is radiated into the main emission direction of the converter area as a whole. In the main emission direction of the secondary light there is typically an optical system ("coupling-out") for beam shaping of the mixed light emitted by the converter region. Usually, the converter region (phosphor) is applied to a reflective running surface of a heat sink.

In addition, a specular reflection of the primary laser radiation ("primary light reflection") results from the reflection of a portion of the non-converted primary light from the front of the converter area and the reflection of a portion of the non-converted primary light from the reflective surface of a heat sink on which the converter area (phosphor ) is arranged or attached. If the coupling-out optics is arranged in the main emission direction, the specular reflection will generally not hit them directly if the primary light (measured against the surface normal of the converter region) falls on the converter region at an oblique angle of incidence. The light contained in the primary light reflection is thus lost as useful light and / or may even have undesirable side effects such as e.g. create a glare etc.

This problem has been solved by avoiding an oblique incidence.

It is the object of the present invention to at least partially overcome the disadvantages of the prior art.

This object is achieved according to the features of the independent claims. Preferred embodiments are in particular the dependent claims.

The object is achieved by a remote phosphor lighting device, as a lighting device in which the phosphor is removed from an associated semiconductor source or spaced apart. The remote phosphor lighting device furthermore has a converter region which can be obliquely irradiated by the semiconductor light source. The main emission direction of the primary light, which has the highest radiation intensity, is thus not collinear with a surface normal of the irradiated surface of the converter region. The converter area is applied to an opaque base and thus in a reflective arrangement. An output coupling device connected downstream of the converter region is arranged in a main emission direction of a secondary light generated by the converter region. The lighting device furthermore has at least one return-reflecting mirror which is arranged next to the main emission direction of the secondary light and is arranged and arranged to deflect back a primary light component reflected from the converter region onto the converter region.

This lighting device has the advantage that by means of the reflecting mirror of the (otherwise lost or disturbing) specularly reflected primary light component is reflected back to the converter area and there is converted back into secondary light. Thus, specular reflections, even higher orders, can be used for wavelength conversion. This increases a luminous efficacy and prevents disturbing primary light effects.

The converter region comprises one or more phosphors which at least partially converts or converts the primary light into secondary light of larger wavelength. The converter region may in particular be formed as a layer or layer, in particular with a thickness of up to several millimeters, preferably of one millimeter or less, in particular of 500 micrometers or less.

The lighting device may generally comprise one or more semiconductor light sources, one or more converter regions and / or one or more reflecting mirrors. The beam of the primary light may be emitted directly from the at least one semiconductor light source, alternatively via a light conducting device such as a glass fiber or a glass fiber bundle.

It is a development that the translucent pad has a heat sink or heat sink. The converter region may in particular be applied directly or via an intermediate layer (for example a thermal paste or another thermal interface material, for example a TIM: "Thermal Interface Material") to the heat sink. In particular, the heat sink may consist of thermally highly conductive material with a thermal conductivity λ of at least 15 W (m · K), e.g. made of metal such as aluminum or copper, ceramic or sapphire.

It is a development that the heat sink is a heat sink that is stationary relative to the light fixture, e.g. a firmly attached solid body.

It is still a development that the heat sink is a movable heat sink, in particular a rotatable heat sink. Such a heat sink may for example be moved by means of a drive motor. The converter area may then move in particular during movement of the heat sink and the primary light beam generated by the at least one semiconductor light source. In particular, the heat sink may have a plurality of converter regions, e.g. with different phosphors and / or phosphor concentrations, which move during the movement of the heat sink alternately under the primary light beam. The heat sink with the at least one converter region may in particular be a rotatable color wheel or light wheel.

The lighting device may be a lamp, a light or a light module. The lighting device may be provided in particular for use in vehicles, so in particular be a vehicle lighting device. The lighting device may in particular be a headlight or a part of a headlight or as a light source for projection systems (video, data, film).

It is an embodiment that the retroreflective mirror lies in a main emission direction of a specular primary light reflection. This allows a reflection of a particularly high proportion of the previously speculatively reflected at the converter area primary light.

It is still an embodiment that the reflecting mirror is a plane mirror or specular reflector. This allows an effective reversion to the converter area, in particular even if the specular reflex is sharp. A flat reflection mirror is particularly easy to produce.

It is still another embodiment that the retroreflecting mirror is a curved mirror. This has the advantage that it can throw back a diverging primary light reflection more effectively on the converter area.

It is a development that curved reflecting mirror has a spherical, paraboloid and / or hyperboloid shaped mirror surface.

It is also an embodiment that the retroreflecting mirror is a multi-segmented mirror, ie may have several different segments or facets, e.g. plane and curved and / or curved in different ways segments.

The retroreflecting mirror may also have a free-form mirror surface.

Due to the different shapes of the mirror surface, deviations from a sharp, essentially non-divergent primary beam reflection can be taken into account. Such deviations may arise, for example, due to second-order reflections, an irregular surface texture of the phosphor region, a diffusely scattering effect of the converter region, and the like. Also, the different segments or facets of the retroreflecting mirror may aim at different positions of the converter area, e.g. to compensate for or at least reduce inhomogeneities in a luminance, e.g. caused by the direct impinging primary light. In particular, for this purpose, the reflecting mirror can also be designed completely as a multifaceted free form.

It is a further embodiment that at least one optical transmitted light element is arranged in the beam path of the primary light between the semiconductor light source and the converter region. This enables an improved focusing of the primary light radiated from the semiconductor light source onto the converter region. The at least one transmitted light element may, for example, comprise at least one lens and / or at least one concentrator, e.g. CPC.

It is also an embodiment that between the semiconductor light source and the converter area at least one further reflecting mirror which is arranged to transmit primary light incident from the semiconductor light source and to reflect light incident from the converter region back to the converter region. This further increases a luminous efficacy, as it is also possible for specular reflections of the primary light component reflected by the reflecting mirror to be thrown back onto the converter region.

It is a development that the further reflecting mirror is a semitransparent mirror. In particular, such a reflecting mirror may also radiate broadly emitted secondary light back onto the converter area.

Alternatively or additionally, the further reflection mirror may be arranged close to the semiconductor light source, in particular be attached thereto and have a small hole for passing the primary light beam emitted by the semiconductor light source.

The semiconductor light source can be present in particular as one or more light-emitting diodes. These are particularly inexpensive to provide. However, the semiconductor light source can also be present as one or more lasers, in particular diode lasers. This allows a particularly sharp and high-energy primary light beam.

The semiconductor light source may also be a so-called multi-die package, in which a plurality of laser diodes (referred to here as multi-die) are arranged on one or more substrate surfaces ("chip-on-submount"). The substrate surfaces are arranged in a common housing (also referred to as "package"). Depending on the adjustment of the laser diodes or the substrate surfaces, this multi-die package can emit a bundle or array of parallel offset laser beams, for example perpendicular to the base of the multi-die arrangement, or, with a focusing adjustment, one focus or multiple focuses emit incoming laser beams.

The above-described characteristics, features, and advantages of this invention, as well as the manner in which they will be achieved, will become clearer and more clearly understood in connection with the following schematic description of exemplary embodiments which will be described in detail in conjunction with the drawings. In this case, the same or equivalent elements may be provided with the same reference numerals for clarity.

1 to 5 show a sectional side view of respective embodiments of a remote phosphor lighting device.

1 shows a remote phosphor lighting device 11 according to a first embodiment, which has at least one semiconductor light source, for example in the form of a laser 12 , By means of the laser 12 is a phosphor containing converter area 13 with, eg blue, primary light P can be irradiated. In this case, the primary light P strikes obliquely on a front side in its main emission direction H1, which is shown horizontally here 14 the converter area 13 on, and at an angle of 45 ° to the surface normal of the front 14 , With her back 15 lies the converter area 13 on a heat sink 16 made of metal, in particular reflective trained metal on. The metal may be, for example, aluminum or copper.

In operation, the primary light P is partially converted from the converter area into eg yellow secondary light S. The secondary light becomes normal to the front with a main radiation direction H2 14 the converter area 13 radiated. The main radiation directions H1 and H2 are thus at an angle of 45 ° to each other. Remaining primary light P is partially by means of the converter area 13 diffused and thus also has a share in the main radiation direction H2 of the secondary light S. Thus, along the main emission direction H2, a mixed light P, S is emitted from the primary light P and the secondary light S. This mixed light P, S passes into a coupling-out optical system arranged in the main emission direction H2 17 and is jet-formed there as useful light.

However, a portion of the primary light P which is not wavelength-converted and does not radiate or radiate only insignificantly remains, which is specularly reflected, in particular on the heat sink 16 , This comparatively sharp (ie, little diverging) specular primary light reflection F arrives at a mirror arranged next to the main emission direction H2 of the secondary light S, namely the plane "reflecting mirror" which is flat here. 18 , The reflecting mirror 18 is arranged and arranged, the specular primary light reflection F on the converter area 13 redirect. The reflecting mirror 18 lies in the direction of the specular primary light reflection F. The primary light reflection F has a main radiation direction H3 perpendicular to the main emission direction H1 of the original primary light P.

2 shows a remote phosphor lighting device 21 according to a second embodiment. The lighting device 21 differs from the lighting device 11 by the use of a, for example Kugelkalottenähnlich or parabolic, curved Rückstrahlspiegels 22 , This also allows a higher divergent primary light reflection F on the converter area 13 to be thrown back.

3 shows a remote phosphor lighting device 31 according to a third embodiment. The lighting device 31 differs from the lighting device 21 by the use of a multi-segment curved reflecting mirror 32 , where different segments 33 . 34 For example, different curvature shapes, angles of curvature, distances to the converter area 13 etc. may have. As a result, for example, irregularities of the front 14 the converter area 13 , Beam expansions of the primary light reflection F, higher-order light intensity maxima of the primary light reflection F etc. are taken into account for effective reverberation.

4 shows a remote phosphor lighting device 41 according to a fourth embodiment. The lighting device 41 has in the beam path of the primary light P between the semiconductor light source 42 and the converter area 13 an optical transmitted light element in the form of a lens 43 on. As a result, one of the semiconductor light source 42 Outgoing, noticeably expanded beam of primary light P on the converter area 13 be focused and / or the beam may be beamformed. The semiconductor light source 42 may be, for example, at least one light emitting diode or laser diode.

5 shows a remote phosphor lighting device 51 according to a fifth embodiment. lighting device 51 additionally has eg to the lighting device 21 another reflection mirror 52 which is located between the semiconductor light source 42 and the converter area 13 located. The further reflection mirror 52 is semipermeable and is adapted to from the semiconductor light source 12 passing incident primary light P and from the converter area 13 incident light back to the converter area 13 to reflect. Alternatively or additionally, the reflecting mirror 52 also be provided with a central opening through which the semiconductor light source 12 irradiated.

Although the invention has been further illustrated and described in detail by the illustrated embodiments, the invention is not so limited and other variations can be derived therefrom by those skilled in the art without departing from the scope of the invention.

Thus, the primary light P may not be emitted directly from the semiconductor light source, but rather via one or more glass fibers or the like. This increases flexibility in the positioning of the semiconductor light source.

The primary light source P may comprise an array of laser diodes of different primary wavelengths.

The angle of incidence of the primary light on the conversion surface can be any value between 0 degrees and 90 degrees to the normal of the conversion surface.

In particular, an angular deviation between the main emission direction of the secondary light and the main emission direction of the primary light reflection may amount to at least five percent, preferably at least 10%, whereby sufficient installation space is provided for convenient mounting of the coupling-out optical system and the reflecting mirror.

Generally, "on", "an", etc. may be taken to mean a singular or a plurality, in particular in the sense of "at least one" or "one or more" etc., unless this is explicitly excluded, e.g. by the expression "exactly one", etc.

Also, a number may include exactly the specified number as well as a usual tolerance range, as long as this is not explicitly excluded.

LIST OF REFERENCE NUMBERS

11

Remote-phosphor device

12

laser

13

converter range

14

Front of the converter area

15

Rear of the converter area

16

heatsink

17

output optical system

18

level reflecting mirror

21

Remote-phosphor device

22

curved reflecting mirror

31

Remote-phosphor device

32

multi-segment curved reflecting mirror

33

Segment of the reflecting mirror

34

Segment of the reflecting mirror

41

Remote-phosphor device

42

Semiconductor light source

43

lens

51

Remote-phosphor device

52

further reflecting mirror

F

Primary light reflex

H1

Main radiation direction of the primary light

H2

Main emission direction of the secondary light

H3

Main beam direction of the primary light reflection

P

primary light

S

secondary light

Claims (10)

Remote phosphor lighting device ( 11 ; 21 ; 31 ; 41 ; 51 ; 61 ), comprising - a semiconductor light source ( 12 ; 42 ) One from the semiconductor light source ( 12 ; 42 ) obliquely irradiable converter area ( 13 ), which converter area ( 13 ) on an opaque base ( 16 ) is applied, - a the converter area ( 13 ) downstream coupling-out optics ( 17 ), which in a main emission direction (H2) of one of the converter region ( 13 ) generated secondary light (S) is arranged and - at least one next to the main radiation direction (H2) of the secondary light (S) arranged return radiation mirror ( 18 ; 22 ; 32 ; 52 ), which reflecting mirror ( 18 ; 22 ; 32 ; 52 ) is arranged and arranged one of the converter area ( 13 ) reflected primary light component (F) on the converter area ( 13 ) to deflect back. Remote phosphor lighting device ( 11 ; 21 ; 31 ; 41 ; 51 ; 61 ) according to claim 1, wherein the reflecting mirror ( 18 ; 22 ; 32 ) is in a main beam direction of a specular primary light reflection (F). Remote phosphor lighting device ( 11 ; 41 ) according to one of the preceding claims, wherein the reflecting mirror ( 18 ) is a plane mirror. Remote phosphor lighting device ( 21 ; 31 ; 51 ) according to one of the preceding claims, wherein the reflecting mirror ( 22 ; 32 ) is a curved mirror. Remote phosphor lighting device ( 31 ) according to one of the preceding claims, wherein the reflecting mirror ( 32 ) is a multi-segmented mirror. Remote phosphor lighting device ( 41 ) according to one of the preceding claims, wherein in the beam path of the primary light (P) between the semiconductor light source ( 42 ) and the converter area ( 13 ) at least one optical transmitted-light element ( 43 ) is arranged. Remote phosphor lighting device ( 51 ) according to one of the preceding claims, wherein between the semiconductor light source ( 12 ) and the converter area ( 13 ) at least one reflecting mirror ( 52 ), which is arranged to be separated from the semiconductor light source ( 12 ) pass incident primary light (P) and from the converter area ( 13 ) incident light (P, S) back to the converter area ( 13 ) to reflect. Remote phosphor lighting device ( 51 ) according to one of the preceding claims, wherein the semiconductor light source ( 12 ; 42 ) at least one laser ( 12 ). Remote phosphor lighting device ( 51 ) according to one of the preceding claims, wherein the semiconductor light source ( 12 ; 42 ) at least one light emitting diode ( 42 ). Remote phosphor lighting device ( 11 ; 21 ; 31 ; 41 ; 51 ; 61 ) according to one of the preceding claims, which is designed as a vehicle lighting device and / or as a video projection device.

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