WO2014037217A1

WO2014037217A1 - Illumination device

Info

Publication number: WO2014037217A1
Application number: PCT/EP2013/067319
Authority: WO
Inventors: David Dussault; Andre Nauen; Sergey Khrushchev; Christian Gammer
Original assignee: Osram Gmbh
Priority date: 2012-09-05
Filing date: 2013-08-20
Publication date: 2014-03-13
Also published as: DE102012215702A1

Abstract

The invention relates to an illumination device that comprises at least one laser light source (10) and at least one light wavelength conversion element (13) which is designed for proportionately converting light, emitted by the at least one laser light source (10), into light of another wavelength. In order to monitor the at least one laser light source, a first light sensor (14) is designed to detect non-converted laser light on the wavelength of the light emitted by said at least one laser light source (10), and a second light sensor (15) is designed to detect converted laser light on the wavelength of the light converted by said at least one light wavelength conversion element (13).

Description

lighting device

The invention relates to a lighting device according to the preamble of claim 1.

I. State of the art

Such a lighting device is disclosed for example in US 2011/0084609 AI. This document describes a lighting device with improved safety for the user. To this end, a light sensor is provided in the lighting device that detects reflected at the light wavelength conversion element light and detects in this manner, the presence or absence of the light wavelength conversion element and a shutdown of the laser light source in the case of the absence of the light wavelength conversion member veran ^¬ initiated.

I i. Presentation of the invention

It is an object of the invention to provide a generic lighting device with improved monitoring of the light emission.

The illumination device according to the invention has at least one laser light source and at least one light wavelength conversion ^{element which is designed} to convert light emitted by the at least one laser light source proportionately into light of a different wavelength. In addition, the illumination device ^{according to} the invention has at least two light sensors for monitoring the light emission for the at least one laser light source le, wherein a first light sensor for detecting unconverted laser light is tuned to the wavelength of the light emitted from the at least one laser light source, and a second light sensor for detecting converted laser light to a wavelength, for example the dominant wavelength, of the at least one light wavelength conversion element converted light is tuned.

The illumination device according to the invention makes it possible with the aid of the light sensors with different spectral sensitivity to determine the relative proportions of converted and unconverted light and thus the detection of any absolute or relative intensity change of the laser light or the converted light or any absolute or relative color location shift of composed of converted and unconverted light mixed light emitted from the illumination device according to the invention. Depending on the size of the color locus shift or the relative change in intensity, a safety shutdown of the at least one laser light source can be activated. Also enables the invention ^shown SSE illumination device to detect both changes in the laser light sources and the at least one light wavelength conversion member. Insbeson ^¬ particular a more accurate localization of possible sources of error in the inventive lighting device is possible.

According to a first preferred embodiment of the invention, the light sensors of the invention Lighting device arranged such that they detect at the at least one light wavelength conversion element scattered, converted or non-converted light. As a result of this arrangement of the light sensors, the light sensors do not disturb the light emission of the illumination device according to the invention, since they are not arranged in the direct beam path of the at least one laser light source.

According to another preferred embodiment of the invention, the first light sensor is arranged such that it is not converted, detected by the at least one La ^¬ serlichtquelle emitted light and the second light sensor is arranged such that it at the at least one optical wavelength conversion element overall interspersed, converted Light detected. The first light sensor is preferably arranged in such a way ^¬ in this case is that it is either scattered light from the detected at least one laser light source, or does not receive Batch Conversion ^¬ tes laser light that is coupled out for example by means of a beam splitter. In this case, the light emission of the illumination device according to the invention is likewise not hindered by the light sensors.

According to a further preferred embodiment of the invention, the Beleuchtungseinrich- invention tung least one light guide, which is so attached ^¬ arranged that converted and non-converted scattered light is coupled from said at least version element a Lichtwellenlängenkon- into the light guide and then the light emerging from the light guide Light on one for the respective spectral component of the converted or unconverted light sensitive light sensor is passed. The use of at least one light guide has the advantage that stray high intensity light with ge ^¬ ringem loss is conducted from the at least one Lichtwellenlän- genkonversionselement to the light sensors and thus a high light intensity of the light sensors is measurable advantage.

Advantageously, an evaluation unit vorgese ^¬ hen and formed such that a quotient of the calculated by the first light sensor and the second light sensor light intensities or a variable proportional thereto is evaluated. Thus, the relative proportion of the converted light and the unconverted light can be determined in the light emitted from of the inventive illumination device in a simple Wei ^¬ se. In addition, the value of such a quotient or a variable proportional thereto can be used as a measure of the color location or any color locus shift of the light emitted by the illumination device according to the invention and defines a threshold for activating a safety shutdown of the laser light sources using this quotient or the size proportional thereto become. Further, the value of such a ratio or a magnitude proportional to a measure of a possible loss of quality when light wave length can conversion-element or assign as an indicator of some ^¬ or complete loss of Lichtwellenlängenkon- version elements are used. Furthermore, the application of the aforementioned quotient Ver ^¬ or to propor- tional size has the advantage that the safety shut tion of the laser light sources and the quality control of the at least one light wavelength conversion element is independent of the absolute values of the light intensities measured by the two light sensors. Both the quotient L1 / L2 and the reciprocal L2 / L1 of this quotient and a variable proportional thereto are suitable for the safety shutdown of the laser light sources and the quality monitoring of the at least one light wavelength conversion element, where LI is the light intensity measured by the first light sensor and L2 is that of the second Light sensor measured measured light intensity.

Preferably, the at least one laser light source is designed so that it emits light from the wavelength ^¬ range of 380 nm to 490 nm and at least one light wavelength conversion element is designed such that it light from the at least one La ^¬ serlichtquelle proportionally in light with a dominant wavelength from the wavelength range of 560 nm to 590 nm converted. This ensures that the illumination device according to the invention emits white light, which is a mixture of unconverted blue light and converted yellow light. The lighting device according to the invention is thereby suitable for use as a light source in a vehicle headlight. The color location of the white light emitted by the illumination device according to the invention is determined by the relative proportions of unconverted blue light and converted yellow light. The term "white light" means that the standard chromaticity coordinates x, y of the illumination unit according to the invention direction of emitted light on the standard color chart according to DIN 5033 correspond to the standard chromaticity coordinates of the black spot at x = 0.333 and y = 0.333 or deviate only slightly from these values. The first light sensor is advantageously tuned to a wavelength range of 380 nm to 490 nm and the second light sensor is preferably tuned to a wavelength range of 560 nm to 590 nm or to wavelengths greater than or equal to 550 nm. This ensures that the first light sensor detects only the on ^¬ part of the non-converted light emitted from the lighting device according to the invention light and the second light sensor detects only the portion of the converted light emitted from the lighting device according to the invention light.

The at least one laser light source is preferably designed as a laser diode or laser diode array in order to enable a spatially compact arrangement of the components of the illumination device according to the invention. III. Description of the preferred embodiments

The invention will be explained in more detail below with reference to preferred exemplary embodiments. Show it:

Figure 1 is a schematic representation of a lighting device according to the first embodiment of the invention

Figure 2 is a schematic representation of a lighting device according to the second embodiment of the invention Figure 3 is a schematic representation of a lighting device according to the third embodiment of the invention

4 shows a cross section through the abgebil ^¬ finished illumination device in Figure 3 in a schematic view along the plane AA

Figure 5 is a schematic representation of a lighting device according to the fourth embodiment of the invention

Figure 6 is a schematic representation of a lighting device according to the fifth embodiment of the invention

Figure 7 is a schematic representation of a lighting device according to the sixth embodiment of the invention

FIG. 1 schematically shows the structure of a lighting device according to the first exemplary embodiment of the invention. This illumination device has a blue light from the wavelength range from 440 nm to 460 nm emitting laser diode 10, a Kolli ^¬ matorlinse 11, designed as a fiber optic light guide 12, a Lichtwellenlängenkonversionselement 13 and two light sensors 14, 15. The laser diode 10 and Kol ^¬ limatorlinse 11 are un ^¬ tergebracht in a common housing 100. The light emitted by the laser diode 10 is parallelized by means of the collimator lens 11 and coupled into a first end 122 of the fiber optic 12. The fiber optic 12 has a light-conducting core 120 and the core 120 surrounding jacket 121, whose material has a lower optical refractive index than the material of the core 120 so that the light coupled into the Fa ^¬ seroptik 12 light remains by total reflection on the casing 121 in the core 120 and the optical fiber 12 only at their Leave ends 122, 123. The blue laser light emerging from the second end 123 impinges on the light wavelength conversion element 13 and is proportionally converted into yellow light after impinging on the Lichtwellenlängenkonversionsele- 13, so that upon passing the light wavelength conversion element 13 white light 16 is generated, which is a mixture of unconverted blue light and converted yellow light is. The illumination device according to the first exemplary embodiment of the invention thus generates white light, which is a mixture of blue excitation light of the laser diode 10 and converted yellow light of the light wavelength conversion element 13. The light wavelength conversion element 13 serves as a light exit opening of the illumination device and, since it has only a small area in the range from 1 mm ² to 5 mm ² , the illumination device can be regarded as a white light emitting point light source, which is very well suited as a light source for projection applications, especially vehicle headlights, is suitable.

The light wavelength conversion member 13 of the BL LEVEL ^¬ processing device according to the first embodiment of the invention consists of a sapphire wafer 130, which is coated with phosphor 131, the blue light in gel bes light having a dominant wavelength from the WEL wavelength range from 560 nm to 590 nm. As the phosphor 131 is doped with cerium Yttriumaluminium ^¬ garnet (YAG: Ce) was used. The relative proportion of unconverted blue light and converted yellow light in the white mixed light 16 is determined by the thickness of the phosphor coating 131 and the concentration of the phosphor on the sapphire chip 130. The blue laser light is scattered on the phosphor particles of the light wavelength conversion element 13, and a part of the blue light is converted to yellow light by the phosphor 131. The sapphire plate 130 serves as a carrier and heat sink for the phosphor 131. The phosphor 131 is attached as a coating on the second end 123 of the fiber optic 12 facing surface of the sapphire plate 130. However, it may also be remote from this on the end 123 of the surface Sa ^¬ phirplättchens 130 may be disposed. The light wavelength conversion element 13 is clamped in a holder (not shown), which additionally serves as a heat sink for the light wavelength conversion element 13.

The first light sensor 14 is designed as a photodiode, which is preceded by a color filter, so that the first photodiode substantially only receives light from the blue spectral range in the wavelength range from 440 nm to 460 nm. The second light sensor 15 is designed as a photodiode, which is preceded by a color filter, so that the second photodiode receives substantially only light from the yellow spectral range in the wavelength range of 560 nm to 590 nm. Alternatively, for example, the color filters can also be designed so that the Color filter of the first light sensor 14 is permeable only to light from the violet and blue spectral range and the color filter of the second light sensor 15 is permeable only for the yellow and red spectral range. The first light sensor 14 is arranged to detect light scattered at the light wavelength conversion element 13 or at the second end 123 of the fiber optic 12. The second light sensor 15 is arranged to detect light scattered at the light wavelength conversion element 13. However, the first light sensor 14 de ^¬ tektiert only unconverted blue light, while the second light sensor 15 detects only converted gel ^¬ bes light. The light intensities detected by the two light sensors 14, 15 are evaluated with the aid egg ner evaluation unit 110, which includes a per ^¬ program controlled microprocessor having data memory (both not shown) to trigger an Si ^¬ cherheitsabschaltung the laser diode 10 in case of failure. To monitor the light emission of the lighting device according to the first embodiment of the invention, the quotient is 15 detected light intensity and detected by the first light sensor 14 light intensity or a proportional to this quotient electrical quantity, for example in the form of an electrical ^¬ from the second light sensor means of the evaluation unit 110 voltage or an electric current, formed and evaluated. This quotient corresponds to the relative proportion of converted yellow light to unconverted blue light in the light emitted by the illuminator. If the value of this quotient or the electrical energy proportional thereto falls see size a predetermined threshold, the safety shutdown for the laser diode 10 is triggered.

For example, in the case of the absence of the light wavelength conversion element 13, there is no converted yellow light, and consequently, the light intensity detected by the second light sensor 15 is zero. Entspre ^¬ accordingly has the value of the quotient of the light from the second sensor 15 and the detected light intensity detected by the first light sensor 14 light intensity likewise zero. In this case, the safety shutdown is triggered for the Laserdi ^¬ ode 10th If the quality of the light wavelength conversion element 13 deteriorates during the operating time of the illumination device, for example because of detached or inactive parts of the phosphor coating 131 or because of an impermissible increase in the intensity of the laser excitation radiation, the relative proportion of the converted yellow light becomes relative to that of the unconverted blue Light sink. Accordingly, this also reduces the value of the aforementioned quotient compared to its initial value, which it had when the phosphor coating 131 was completely intact. This has the consequence that is displaced by the chromaticity coordinates x, y defi ^¬ ned color location of the emit from the illuminating means oriented white light on the standard color table according to DIN 5033 from its initial value toward the blue spectral region and the color temperature of white light of a assumes a higher value. Therefore, the surveil ^¬ monitoring the aforesaid ratio allows additional borrowed for safety shutdown of the laser diode 10 also a monitoring of the shift of color location and color temperature of the light emitted by the illumination device. Accordingly, therefore, in the case of a partially separated or partially inactive luminescent material coating 131, for example, the power of the laser diode 10 can be reduced or the laser diode be abge ^¬ switches as soon as a predefined threshold value of the aforementioned quotient is exceeded.

FIG. 2 schematically shows the structure of a lighting device according to the second exemplary embodiment of the invention. The illumination device according to the second exemplary embodiment of the invention is formed almost completely identical to the illumination device according to the first exemplary embodiment of the invention. The illumination device according to the second embodiment of the invention differs from the illumination device according to the first embodiment of the invention only by the first light sensor 24. Therefore, the same reference numerals are used in Figures 1 and 2 for identical components of the illumination devices in both embodiments of the invention. For their description, reference is made to the description of the components of the first embodiment of the invention. The first light sensor 24 of the illumination device according to the second embodiment of the invention is housed in the housing 100 of the illumination device, and arranged so that it detects unkonver- patented blue light that has been scattered by the collimator ^¬ lens 11 or the optical fiber 12 at the first end or with slight divergence, the laser diode 10 had left. The first light sensor 24 according to the second exemplary embodiment of the invention agrees with the first light sensor 14 according to the first ^exemplary embodiment in all its details. The only difference between the lighting devices according to the first and second embodiment of the invention, therefore, be ^¬ is the fact that in the illumination device according to the second embodiment of the invention the non-converted blue portion of the light directly to the laser diode 10 and the first end 122 the optical fiber is detected, while the optical fiber 123 is detected in the lighting device according to the first embodiment of the invention the non-converted blue portion of the light at the second en ^¬ de. The operation of the illumination device according to the second embodiment of the invention is identical to the func ^¬ onsweise of the illumination device according to the first embodiment of the invention.

In the figures 3 and 4, the structure of a lighting device according to the third embodiment of the invention is shown schematically. This illumination device has four, blue light from the wavelength range of 440 nm to 460 nm emitting laser diodes 30a, 30b, each a collimator lens 31a, 31b for each of the four laser diodes 30a, 30b each formed as Faserop ^¬ tik optical fiber 32a, 32b, 32c, 32d for each of the four laser diodes 30a, 30b, a light wavelength conversion element 33 and two light sensors 34, 35 and a fifth fiber optic 32e associated with the light sensors 34, 35. In Fig. 3, of the four laser diodes 30a, 30b and their associated four collimator lenses 31a, 31b only two visible. The Figures 30a, 30b emitted light from the Laserdio ^¬ is parallelized in each case by means of the corresponding collimator lens 31a and 31b in a first end 321a, 321b of the corresponding Faserop ^¬ tik 32a, 32b, 32c and 32d coupled. The from the second end 322a, 322b of the optical fibers 32a, 32b, 32c and 32d emerging blue laser light is incident on the light wavelength conversion member 33 and is converted after impinging on the light wavelength conversion element 33 proportionally to yellow light, so that when Pas ^¬ Sieren of the light wavelength conversion member 33 white light 36 is generated, which is a mixture of non kon ^¬ vertiertem-converted blue light and yellow light. The illumination device according to the third exemplary embodiment of the invention thus generates white light, which is a mixture of blue excitation light of the four laser diodes 30a, 30b and converted yellow light of the light wavelength conversion element 33. The light wavelength ^{conversion element} 33 serves as a light ^{¬ outlet} opening of the illumination device and since it sits ^¬ only a small area in the range of 1 mm ² to 5 mm ² , the illumination device can be regarded as a white light emitting point light source, which is very good as a light source for projection applications, especially vehicle headlights, is suitable.

The light wavelength conversion member 33 of the BL LEVEL ^¬ processing device according to the third embodiment of the invention consists of a sapphire wafer 330, which is coated with phosphor 331, the blue light in converted yellow light with a dominant wavelength from the wavelength range of 560 nm to 590 nm. As the phosphor 331 with cerium doped Yttriumalumi ^¬ niumgranat (YAG: Ce) is used. The relative proportion of unconverted blue light and converted yellow light in the white mixed light 36 is determined by the thickness of the phosphor coating 331 and the concentration of the phosphor on the sapphire wafer 330. The blue laser light is scattered on the phosphor particles of the light wavelength conversion element 33, and a part of the blue light is converted into yellow light by the phosphor 331. The sapphire wafer 330 serves as a support and heat sink for the phosphor 331. The phosphor 331 is attached as a coating on the surface of the sapphire wafer 330 facing the second ends 322 of the fiber optics 32a, 32b, 32c, 32d. However, it can also be arranged on the surface of the sapphire plate 330 facing away from these ends. The light wavelength conversion element 33 is clamped in a holder (not shown), which additionally serves as a heat sink for the light wavelength conversion element 33.

The light sensors 34, 35 associated fifth Faserop ^¬ tik 32e extends within a seroptiken from the other four Fa 32a, 32b, 32c, 32d formed channel. The fifth fiber optic 32e is arranged such that light scattered or reflected at the light wavelength conversion element 33, both converted and unconverted, is coupled into one end of the fifth fiber optic 32e and to the other end the fifth fiber optic 32e arranged light sensors 34, 35 is passed. The first light sensor 34 is formed as a photo ^¬ diode, which is ^preceded by a color filter, so that the first photodiode receives substantially only light from the blue spectral range in the wavelength range of 440 nm to 460 nm. The second light sensor 35 is formed as a photodiode, which is pre-tet scarf ^¬ a color filter, so that the second photodiode is substantially only receives light from the yellow spectral region in the wavelength range of 560 nm to 590 nm. Alternatively, the color filters may, for example, also be designed such that the color filter of the first light sensor 34 is permeable only to light from the violet and blue spectral range and the color filter for the second light sensor 35 is permeable only to the yellow and red spectral range. The first light sensor 34 detects only unconverted blue light while the second light sensor 35 detects only converted yellow light. The light intensities detected by the two light sensors 34, 35 are evaluated with the aid of an evaluation unit which has a program-controlled micropro ^¬ zessors with data memory (both not shown) has ^¬ to trigger a fault occurs a safety shutdown of the four laser diodes 30a, 30b. For monitoring the light emission of the illumination device according to the third exemplary embodiment of the invention, the quotient of the light intensity detected by the second light sensor 35 and the light intensity detected by the first light sensor 34 or an electric variable proportional to this quotient, for example in the form of an electrical voltage or a voltage electric current, forms and evaluates. This quotient corresponds to the relative proportion of converted yellow light to unconverted blue light in the light emitted by the illumination device. If the value of this quotient or electric variable proportional thereto falls below a predetermined threshold value, a safety shutdown of the four laser diodes 30a, 30b is triggered.

For example, in the case of the absence of the light wavelength conversion element 33, there is no converted yellow light, and consequently, the light intensity detected by the second light sensor 35 is zero. Entspre ^¬ accordingly has the value of the quotient of the light from the second sensor 35 and the detected light intensity detected by the first light sensor 34 light intensity also has the value zero. In this case, the four La ^¬ serdioden 30a, 30b are turned off. Deteriorated during the operating lifetime of the illumination device, the quality of the light wavelength conversion member 33, for example due to the detached or inactive parts of the phosphor coating 331 or due to an unacceptable increase in intensity of the laser excitation radiation, the relative proportion of the converted gel ^¬ ben light into reference is to that of the non-converted blue - sink in the light. Accordingly, the value of the abovementioned quotient is also reduced in comparison with its initial value, which it had when the ^phosphor coating 331 was completely intact. This has the consequence that the color location of the light emitted by the illumination device is defined by the standard color value components x, y white light on the standard color table according to DIN 5033 is displaced from its initial value toward the blue spectral region and the color temperature of white light ^¬ SEN assumes a higher value. Therefore, in addition to the safety shutdown of the four laser diodes 30a, 30b, the monitoring of the abovementioned quotient also allows a monitoring of the shift in color locus and color temperature of the light emitted by the illumination device. Accordingly, therefore, in the case of a partially separated or partially inactive light ^¬ material coating 331, for example, the performance of the four laser diodes 30a can be reduced 30b or the laser diodes 30a are turned off 30b when a prede ^¬ finierter threshold value of the aforementioned quotient is undershot.

FIG. 5 schematically shows the structure of a lighting device according to the fourth exemplary embodiment of the invention. This illumination device has a blue light from the wavelength range of 440 nm to 460 nm emitting laser diode 40, a Kolli ^¬ matorlinse 41, a light wavelength conversion element 43 and two light sensors 44, 45. The emitted light from the laser diode 40 is parallelized by means of the collimator lens 41 and directed in the direction of the Lichtwellenlängenkon- conversion element 43 so that it impinges on the surface of the Lichtwellenlängen- conversion element 43 at a Win ^¬ angle of 45 degrees.

The light wavelength conversion member 43 of the BL LEVEL ^¬ processing device according to the fourth embodiment of the invention consists of a sapphire wafer 430, the is coated with phosphor 431, which converts blue light into yellow light having a dominant wavelength from the wavelength range of 560 nm to 590 nm. The phosphor 431 used is cerium-doped yttrium aluminum granulate (YAG: Ce). The relative proportion of unconverted blue light and converted yellow light in the white mixed light 46 is determined by the thickness of the phosphor coating 431 and the concentration of the phosphor on the sapphire wafer 430. The blue laser light is scattered on the phosphor particles of the light wavelength conversion element 43, and a part of the blue light is converted to yellow light by the phosphor 431. The sapphire wafer 430 serves as a support and a heat sink for the phosphor 431. The phosphor 431 is applied as a coating on the side facing away from the laser diode 40 surface of the sapphire wafer 430, which is also referred to as rear side of the Saphirplätt ^¬ Chen 430th The coated phosphor ^¬ material 431 as well as the rear side edge of the sapphire wafer 430 are covered with a light re ^¬ inflecting layer 432nd Both the non-converted blue portion of the light and the yellow Conver ^¬ oriented portion of the light reflected at the light re ^¬ inflecting coating 432 so that WEI SLI light 46, which is a mixture of non-converted blue light and yellow light Converted , the light wavelength conversion element 43 leaves on the rear ^¬ side opposite front side of the sapphire plate 430. The white light 46 emerging at the front side of the sapphire wafer 430 is due to the scattering on the particles of the phosphor coating 431 in unseen emitted different directions. In contrast, the narrowly focused blue laser light 47 impinges on the front side of the sapphire plate 430 at an angle of 45 degrees. The light-reflecting coating 432 in each case has an opening for the two light sensors 44, 45 arranged on the rear side of the sapphire wafer 430. The first light sensor 44 is designed as a photodiode, which is preceded by a color filter, so that the first photodiode essentially only receives light from the blue spectral range in the wavelength range from 440 nm to 460 nm. The second light sensor 45 is designed as a photodiode, which is preceded by a color filter, so that the second photodiode essentially only receives light from the yellow spectral range in the wavelength range from 560 nm to 590 nm. Alternatively, the color filters may, for example, also be designed so that the color filter of the first light sensor 44 is permeable only to light from the violet and blue spectral range and the color filter for the second light sensor 45 is permeable only to the yellow and red spectral range. However, the first light sensor 44 detects only unconverted blue light, while the second Lichtsen ^¬ sensor 45 detects only converted yellow light. The evaluation of the light intensities detected by the light sensors 44, 45 takes place in the same way as in the case of the light sensors 14, 15 of the illumination device according to the first exemplary embodiment of the invention. The light wavelength conversion element 43 is arranged in a would be arranged as a heat sink formed metallic holder 400.

FIG. 6 schematically shows the structure of a lighting device according to the fifth exemplary embodiment of the invention. This illumination device has a blue light from the wavelength range of 440 nm to 460 nm emitting laser diode 50, a Kolli ^¬ matorlinse 51, a fiber optic 52, a Lichtwellenlängen- conversion element 53, a light scattering body 56, and two light sensors 54, 55 and a holder for the light wavelength conversion element 53 and the light scattering body 56. The light emitted by the laser diode 50 is collimated by means of the collimator lens 51 and directed by the fiber optic 52 onto the light scattering body 56. The light-diffusing body 56 has two opposing surfaces, hereinafter referred to as front and back of the light-diffusing body 56. The light wavelength conversion element 53 is arranged on the front side of the light-scattering body 56, and the two light sensors 54, 55 are arranged on the rear side of the light-scattering body 56.

The light wavelength conversion member 53 of the BL LEVEL ^¬ processing device according to the fifth embodiment of the invention consists of a sapphire wafer 530, which is coated with phosphor 531, which converts blue light into yellow light having a dominant wavelength from the wavelength range of 560 nm to 590 nm. The phosphor 131 used is cerium-doped yttrium aluminum granulate (YAG: Ce). The relative share of unconverted blue light and converted yellow light in the white mixed light 57 is determined by the thickness of the phosphor coating 531 and the concentration of the phosphor on the sapphire chip 530. The blue laser light is scattered on the phosphor particles of the light wavelength conversion element 53, and a part of the blue light is converted to yellow light by the phosphor 531. The sapphire chip 530 serves as a carrier and heat sink for the phosphor 531. The phosphor 531 is applied as a coating on the surface of the sapphire plate 530 facing the light-scattering body 56. However, it can also be arranged on the light-scattering body 56 facing away from the surface of the sapphire plate 530. The light wavelength conversion element 53 is clamped together with the light scattering body 56 in a holder 500, which additionally serves as a heat sink for the light wavelength conversion element 53.

The first light sensor 54 is designed as a photodiode, which is preceded by a color filter, so that the first photodiode substantially only receives light from the blue spectral range in the wavelength range from 440 nm to 460 nm. The second light sensor 55 is designed as a photodiode, which is preceded by a color filter, so that the second photodiode receives substantially only light from the yellow spectral range in the wavelength range of 560 nm to 590 nm. Alternatively, the color filters may, for example, also be designed such that the color filter of the first light sensor 54 is permeable only to light from the violet and blue spectral range and the color filter for the second light sensor 55 is transparent only to the yellow and red spectral regions.

The blue laser light coupled into the light scattering body 56 with the aid of the fiber optic 52 is scattered in different directions so that it strikes both the phosphor layer 531 of the light wavelength conversion element 53 and the light sensors 54, 55. The blue scattered light, we detected by the first Lichtsen ^¬ sor 54th A portion of the incident light on the phosphor layer 531 light is converted into yellow light and also scattered in different directions, so that at the side facing away from the light-scattering body 56 surface of the sapphire 530 white light 57 emerges, which is a mixture of unconverted blue light and converted yellow light is. A part of the converted yellow light is scattered toward the light sensors 54, 55 and detected by the second light sensor 55. The evaluation of the light intensities detected by the two light sensors 54, 55 takes place analogously to the evaluation which has been described with reference to the light sensors 14, 15 of the illumination device according to the first exemplary embodiment of the invention.

FIG. 7 schematically shows the structure of a lighting device according to the sixth exemplary embodiment of the invention. This illumination device has two, blue light from the wavelength range from 440 nm to 460 nm emitting laser diodes 60a, 60b, each ^¬ Weils a collimator lens 61a, 61b for each of the Laserdi- oden, designed as a fiber optic light guide 62, a light wavelength conversion element 63, two light ^¬ sensors 64, 65, a light beam splitter 66 and a test light source 67th

The light emitted from the laser diodes 60a, 60b is Siert light parallelized by means of the collimator lenses 61a and 61b and 62 is ^¬ coupled into a first end 622 of the fiber optics. The blue laser light emerging from the second end 623 impinges on the light wavelength conversion element 63 and is proportionally converted into yellow light after impinging on the light wavelength conversion element 63, so that upon passing the light wavelength conversion element 63 white light 68 is generated, which is a light source Mixture of unconverted blue light and converted yellow light is. The illumination device according to the sixth exemplary embodiment of the invention thus generates white light, which is a mixture of blue excitation light of the laser diodes 60a, 60b and converted yellow light of the light wavelength conversion element 63. The light wavelength conversion element 63 serves as light ^{exit opening of} the illumination device and since it has only a small area in the range from 1 mm ² to 5 mm ² , the illumination device can be regarded as a white light emitting point light source which is very well suited as a light source for pro- j ektionsanwendungen, especially vehicle headlights, is suitable.

The light wavelength conversion member 63 of the BL LEVEL ^¬ processing device according to the sixth embodiment of the invention consists of a sapphire wafer 630, which is coated with phosphor 631, the blue light in converted yellow light with a dominant wavelength from the wavelength range of 560 nm to 590 nm. As the phosphor 631 with cerium doped Yttriumalumi ^¬ niumgranat (YAG: Ce) is used. The relative proportion of unconverted blue light and converted yellow light in the white mixed light 68 is determined by the thickness of the phosphor coating 631 and the concentration of the phosphor on the sapphire chip 630. The blue laser light is scattered on the phosphor particles of the light wavelength conversion element 63, and a part of the blue light is converted into yellow light by the phosphor 631. The sapphire chip 630 serves as a support and heat sink for the phosphor 131. The phosphor 631 is applied as a coating on the surface of the sapphire chip 630 facing the second end 623 of the fiber optic 62. However, it may also be remote from this on the end 623 of the surface Sa ^¬ phirplättchens 630 may be disposed. The light wavelength conversion element 63 is in a holder (not shown) clamped, which also serves as Kühlkör ^¬ by the light wavelength conversion element 63rd

In the probe light source 67 is a laser ^¬ diode that is either identical design to the laser diodes 60a, 60b and also emits blue light or emits electromagnetic radiation or light from an at ^¬ whose wavelength range for the wavelength conversion element, the light 63 has a high degree of reflection ^¬ . The light emitted by the test light source 67, after passing through a beam splitter 66, is injected into the first end 622 of the fiber optic 62 with an incident beam. angle of zero degrees coupled. A portion of the light exiting from the second end 623 of the fiber optics 62 of the test light source 67 is reflected at the Lichtwellenlängenkonversi- onselement 63 and coupled back into the second end 623 of the fiber optics 62 so that after exiting the first end 622 of the fiber optics 62 and is detected by the first light sensor 64 after reflection at the beam splitter 66. The second light sensor 65 is arranged such that it detects light scattered at the light wavelength conversion element 63.

The first light sensor 64 is designed as a photodiode, which is preceded by a color filter, so that the first photodiode substantially only receives light from the wavelength range corresponding to the wavelength of the light emitted from the test light source 67. The second light sensor 65 is designed as a photodiode, which is preceded by a color filter, so that the second Fotodio ^¬ de essentially only receives light from the yellow spectral range in the wavelength range of 560 nm to 590 nm. The first light sensor 64 is arranged to detect unconverted light emitted from the test light source 67. The second light sensor 65 is arranged to detect light that has been scattered at the light wavelength conversion element 63 and converted to yellow light. The light intensities detected by the two light ^¬ sensors 64, 65 are evaluated in the same manner as in the first embodiment of the invention, a secure ^¬ in case of failure uniform shutdown of the laser diodes 60a, 60b and the test light source trigger 67th The fiber optics 32a, 32b, 32c, 32d, 32e, 52 and 62 be ^¬ sit the same construction as the fiber optic 12 according to the first embodiment of the invention. The illustration of the light-conducting core and the sheath of the fiber optics has been omitted in FIGS. 3, 4, 6 and 7 for the sake of simplicity.

The evaluation units 110 for the intensities detected by the light sensors and the safety shutdowns for the laser diodes according to the exemplary embodiments described above can be implemented in a simple manner by means of a program installed in the microprocessor of the evaluation ^units , which, in the event of a fault, for example ^falling below a certain threshold value of the above quotient L2 / L1 mentioned above, the laser diodes off and optionally additionally causes the closing of the light exit opening of the illumination device by means of a diaphragm. The switching off of the laser diodes ^¬ processing occurs within a few nanoseconds. The invention is not limited to the above-described embodiments of the invention. In ^¬ play emitting laser diodes and the light ^¬ provided with a yellow phosphor wavelength conversion element, laser diodes which emit light of other colors can take blue light and light wavelength conversion elements can be used with differently colored light generating phosphors. Accordingly, the light sensors can also be adapted to these light wavelength conversion elements. The spectral range on which this invention is based comprises infrared, visible and ultraviolet radiation. In addition, the light wave can wavelength conversion element movable, for example, egg ^¬ ne axis to be rotatable and be formed for example as a color wheel, which is coated with different phosphors to generate light of different colors, and is formed for example as part of a projection apparatus. Accordingly Kgs ^¬ NEN more light sensors may be provided for the converted light from the various phosphors to detect the relative proportions of converted and unconverted light for each phosphor, and to determine the color location shift over the operating life of the lighting device.

In addition to the evaluation of the relative proportions of converted and unconverted light, heating of the light wavelength conversion member may be monitored via ^¬ with the aid of a temperature sensor or an infrared sensor, which sion elements is produced by the so-called Stokes shift in the phosphor of the Lichtwellenlängenkonver-. To hide to other causes to ^¬ recirculated heating of Lichtwellenlängenkonversi- onselements, at the temperature measurement, the combination of modulation of the laser light and ^so-¬-called lock-in technique can be performed. That is, the temperature measurement is made in synchronism with a certain phase of the modulated laser light.

The measuring and evaluation device can be calibrated or contain a self-calibration function. A calibration can, for example, take place before the beginning of each start-up of the illumination device. The Ka- For example, calibration can be performed with very low laser power.

The excitation light sources can be clocked or operated in continuous wave mode, or in a combination of both modes.

All the embodiments also function without the optical fibers arranged upstream of the laser light sources, as fiber optics, since the laser beams can also be directed directly to the wavelength converting light wavelength conversion element. Here, the Metho ^¬ de signal strength measurement is independent of how the laser beams ge to the light wavelength conversion element ^¬ leads are. In addition, instead of the fiber optics other forms of optical fibers, for example so-called TIR optics based on the principle of total internal reflection, or even reflectors or a combination of fiber optics and TIR optics or a combination of fiber optics and reflectors can be used.

In the second exemplary embodiment depicted in FIG. 2, the second light sensor 15 can also be accommodated in the housing 100 since yellow light which has been scattered and converted at the light wavelength conversion element 13 is coupled into the fiber optic 12 and thus returned to the first end 122 of the fiber optic 12 , which can then be detected by the second light sensor 15.

The term scattered light or scattered light to walls ^¬ ren both the light wavelength conversion element or optical elements scattered, unconverted laser and the converted light emitted by the light wavelength conversion element.

Claims

claims

Lighting device with at least one laser light source (10) and at least one light wavelength conversion element (13, 33, 43, 53, 63), which is adapted from the at least one La ^¬ serlichtquelle (10, 30a, 30b, 40, 50, 60a , 60b convert) light emitted proportionately in light of other wave ^¬ length, wherein the illumination device at least one light sensor for monitoring the light emission for the at least one laser light source (10, 30a, 30b, 40, 50, 60a, 60b),

characterized in that at least two light ^¬ sensors (14, 15, 24, 34, 35, 44, 45, 54, 55, 64, 65) are provided, wherein a first light sensor

(14, 24, 34, 44, 54, 64) for detecting of non-converted laser light on the wavelength of the of the at least one laser light source (10, 30a, 30b, 40, 50, 60a, 60b) emitted light abge ^¬ true and wherein a second light sensor

(15,35, 45, 55, 65) for detecting of converted laser light on the wavelength of the of the min ^¬ least one optical wavelength conversion element

(13, 33, 43, 53, 63) converted light is abge ^¬ true.

Lighting device according to claim 1, wherein the light sensors (14, 15, 24, 34, 35, 44, 45, 54, 55, 64, 65) are arranged such that they are connected to the at least one light wavelength conversion element. detect scattered or reflected light.

Lighting means is arranged according to claim 1 or 2, wherein the first light sensor (24) is arranged such that it detects not converted, light emitted from the Minim ^¬ least a laser light source (10) light and the second light sensor (15) such that it on which at least one light wavelength conversion element (13) scattered light detected.

Lighting device according to one of claims 1 to 3, wherein the illumination device has at least one light guide (32e) which is so attached ^¬ arranged that scattered light from the at least ei ^¬ NEN light wavelength conversion element (33) into the light guide (32e) is coupled in and out of the Light guide (32e) emergent light on the light ^¬ sensors (34, 35).

Lighting device according to one of claims 1 to 4, wherein an evaluation unit (110) vorgese ^¬ hen and is designed such that a quotient of the of the first light sensor (14, 24, 34, 44, 54, 64) and of the second light sensor (15, 35, 45, 55, 65) detected light intensities or a signal proportional thereto is evaluated.

Lighting device according to one of claims 1 to 5, wherein the at least one laser light source (10, 30a, 30b, 40, 50, 60a, 60b) is designed such that it light from the wavelength range of 380 nm to 490 nm, and that at least ei ^¬ ne light wavelength ^{conversion element} (13, 33, 43, 53, 63) is designed such that it receives light from the at least one laser light source (10, 30a, 30b, 40, 50, 60a, 60b) proportionally converted into light having a dominant wavelength from the wavelength range of 560 nm to 590 nm.

7. Lighting device according to claim 6, wherein the first light sensor (14, 24, 34, 44, 54, 64) is tuned to a wavelength range of 380 nm to 490 nm and the second light sensor (15, 35, 45, 55, 65) is tuned to a wavelength range of 560 nm to 590 nm or to wavelengths greater than or equal to 550 nm.

Lighting device according to one of claims 1 to 7, wherein the at least one laser light source (10, 30a, 30b, 40, 50, 60a, 60b) is designed as a laser diode.