Irradiation device with fluorescent element

Abstract

Irradiation device with a pump radiation source (70) for emitting pump radiation (71), a phosphor element (2) for converting the pump radiation (71) into a conversion radiation, a piezo element (3) with electrical connection points (4a, b) via which the piezo element (3) can be contacted for an electrical measurement, and a carrier substrate (7) on which the phosphor element (2) and the piezo element (3) are arranged, namely next to one another on the same side thereof, wherein the pump radiation source (70) and the phosphor element (2) are arranged relative to one another in such a way that the pump radiation (71) emitted by the pump radiation source (70) during operation strikes the phosphor element (2) with a main irradiation direction, and wherein the piezo element (3) is designed such that it encloses the phosphor element (2) as seen in the main irradiation direction, so that the mechanical integrity of the phosphor element (2) can be monitored by means of the electrical measurement of the piezo element (3).

Description

Technical area

[0001] The present invention relates to an irradiation device having a phosphor element for at least partially converting pump radiation emitted by a pump radiation source into conversion radiation. State of the art

[0002] High-luminance light sources can be realized, for example, by combining a high-power density pump radiation source, e.g., a laser, with a phosphor element arranged at a distance from it, which emits conversion radiation when excited by the pump radiation. The entire pump radiation can be converted in the phosphor element (full conversion) or just a portion of it, with the portion of unconverted pump radiation then being used together with the conversion radiation (partial conversion). The pump radiation can be blue light, for example, which, in the case of partial conversion, can then, for example, be mixed with yellow light as conversion radiation to produce white light for illumination. A suitable yellow phosphor could be cerium-doped yttrium aluminum garnet (YAG:Ce).

[0003] For example, DE 10 2014 014 852 B3 and DE 20 2015 001 682 U1 disclose lighting devices for a vehicle, each of which has a laser light source and a light conversion element. Description of the invention

[0004] The present invention is based on the technical problem of providing a particularly advantageous irradiation device with a phosphor element.

[0005] According to the invention, this object is achieved by an irradiation device having a pump radiation source for emitting pump radiation, a phosphor element for converting the pump radiation into conversion radiation, a piezo element with electrical connection points via which the piezo element can be contacted for an electrical measurement, and a carrier substrate on which the phosphor element and the piezo element are arranged, specifically next to one another on the same side thereof, wherein the pump radiation source and the phosphor element are arranged relative to one another in such a way that the pump radiation emitted by the pump radiation source during operation strikes the phosphor element with a main irradiation direction, and wherein the piezo element is designed in such a way that it encloses the phosphor element as seen in the main irradiation direction, so that a mechanical integrity of the phosphor element can be monitored with the electrical measurement of the piezo element; as well as an irradiation device with the same components (not necessarily with a carrier substrate), wherein the phosphor element and the piezo element are arranged such that a vertical projection of the phosphor element into a projection plane perpendicular to the main irradiation direction at least partially overlaps with a vertical projection of the piezo element into the same projection plane.

[0006] Preferred embodiments can be found in the dependent claims and the entire disclosure, whereby the description does not always distinguish in detail between device and method or use aspects; in any case, the disclosure is to be read implicitly with regard to all claim categories.

[0007] According to the first variant, the phosphor and piezo elements are arranged on the same side of a carrier substrate and adjacent to each other, with the piezo element enclosing the phosphor element (relative to one circumference around a thickness direction, see below, completely circumferential, i.e., self-contained). With respect to the surface directions (see below), the phosphor and piezo elements can also be adjacent to each other; preferably, they are spaced apart from each other.

[0008] In the second variant, the phosphor and piezo elements are arranged at least partially overlapping in the main beam direction (although they can also be arranged on opposite sides of a carrier substrate, for example). Both variants allow for good mechanical coupling between the phosphor and piezo elements, and the mechanical integrity of the phosphor element—that is, the presence of the phosphor element in an intact state—can be monitored via electrical measurements on the piezo element.

[0009] For example, it can be checked during operation of the irradiation device or during breaks in operation whether the entire phosphor element is in its intended mounting location. In the event of a fault, i.e. if the phosphor element is missing (has fallen off) or is defective, the concentrated pump radiation could propagate through an optic intended for dissipating the conversion radiation. This would pose a significant hazard to an observer, potentially resulting in retinal damage and, in the worst case, loss of vision. By comparison, even in the case of partial conversion during normal operation, some pump radiation propagates through the illumination optics, but its radiance is significantly lower due to conversion and, in particular, scattering processes in the phosphor element.

[0010] The piezo element provided according to the invention is mechanically well coupled to the phosphor element due to its arrangement – ​​see the two basic variants (enclosing or overlapping). A change in the phosphor element, e.g., falling off or even breaking / tearing, changes the mechanical framework of the piezo element. In general, an arrangement is also conceivable in which the piezo element deforms when the phosphor element is detached or damaged, for example, if the two elements are intrinsically clamped to each other.

[0011] Any deformation of the piezo element that occurs in the event of a fault could be detected, for example, by measuring the electrical voltage or a voltage change at the connection points. The connection points are preferably used for resonance measurements, and a fallen-off / damaged phosphor element is detected by a change in vibration behavior; see below for details. Regardless of the specifics, in the event of a fault, the pump radiation input can be at least reduced, preferably completely prevented, for example, by switching off the pump radiation source (but also mechanically, e.g., with a shutter).

[0012] The inventive concept ideally makes it possible to detect not only total failure (a phosphor element falling off), but also degradation in the form of edge- or center-centered cracking (which can result in a complete fracture) or partial detachment or migration of phosphor element material, for example, via the changed vibration behavior of the composite (composed of phosphor and piezo element). Cracks can also influence the vibration or resonance behavior. Cracking in the phosphor element can, for example, be thermally induced, i.e., result from a temperature gradient during the irradiation of the pump radiation or from temperature fluctuations during use. Chemical changes in the phosphor can also be detected if they are accompanied by a mass change and / or migration of phosphor element material.

[0013] An arrangement "on," for example, the phosphor or piezo element arranged "on" the carrier substrate in the first variant, generally does not necessarily mean directly adjacent to it. Thus, another layer can also be provided in between, e.g., a joining layer used for assembly, such as a layer of adhesive, such as bonded glass. This also explicitly applies to the variant described below, "phosphor and piezo element on opposite sides of the carrier substrate."

[0014] The phosphor element is preferably a single piece, meaning that different regions thereof cannot be separated from one another without causing damage. It can, for example, comprise a matrix material, such as a ceramic, glass, or even a plastic material, in which the phosphor is distributed across discrete regions, e.g., in grains of the ceramic or molded into the glass / plastic in particle form. The phosphor element can, for example, also be a monocrystal of the phosphor, such as a YAG:Ce monocrystal. In the cracking / fracture formation discussed above, such a monocrystal, the matrix material, or the phosphor itself could be locally separated.

[0015] The phosphor element can be operated in partial or full conversion mode; explicit reference is made to the information in the prior art assessment. Both reflection operation, in which the incident and emitting surfaces of the phosphor element coincide, and transmission operation, in which the two are opposite each other, are possible. The "incident surface" is irradiated with the pump radiation, and the conversion radiation (and any portion of the unconverted pump radiation) is dissipated at the emitting surface, which is preferably associated with a corresponding optical system, e.g., a lens system.The incident irradiation area is the area of ​​a generally larger side surface of the phosphor element that is actually irradiated with pump radiation. The side surface with the incident irradiation area is preferably the "back," especially during transmission operation; however, the incident irradiation area can generally also be located on the front. The emission area is correspondingly the area of ​​a generally larger side surface of the phosphor element from which the conversion radiation (and any portion of the unconverted pump radiation) is emitted.

[0016] Alternatively, or in addition to the previously discussed laser, an LED (light-emitting diode, preferably a light-emitting diode) can also be used as the pump radiation source, for example, based on InGaN or AlInGaP, but also on an organic basis (organic LED, OLED). Unlike a laser, an LED emits light at a wider angle, e.g., Lambertian.

[0017] A laser is preferred as the pump radiation source, which can, for example, also be constructed from several individual laser sources. "Several" means at least two, whereby at least three, four, five, six, seven, eight, nine, or ten further lower limits can be specified; possible upper limits (independently of this) can be, for example, at most 500,000, 400,000, 300,000, 200,000, 100,000, 50,000, 10,000, 1,000, 500, 250, 100, 50, or 20. In the case of several individual laser sources, their beam bundles can be combined, for example, via beam compression optics and then superimposed onto the phosphor element. A laser diode is preferred as the individual laser source, although a single laser diode can also form the pump radiation source. As an alternative to superposition, each individual laser source can also irradiate a partial area of ​​the phosphor, whereby the irradiated partial areas do not overlap at least partially.

[0018] In general, the conversion is preferably down-conversion, meaning the conversion radiation has a lower energy (longer wavelength) than the pump radiation. The pump radiation is preferably blue light. Although conversion radiation in the infrared range is also generally conceivable (e.g., for night vision or data transmission), this is preferably visible light. The conversion radiation can preferably form white light on its own (full conversion) or in a mixture with a proportion of unconverted pump radiation (partial conversion); in general, however, the object is not limited to this and can also emit colored light (e.g., red, green, and / or blue, also sequentially and / or supplemented with other colors).

[0019] In a preferred embodiment, a measuring unit is provided that can be connected to the electrical connection points of the piezo element, preferably connected thereto. The measuring unit is preferably configured to measure the resonance of the piezo element, thus allowing a change in resonance behavior resulting from a degraded or at least partially detached phosphor element to be detected. A resonance frequency measurement is preferred, which can be performed, for example, as a frequency sweep. With a damaged or detached phosphor element, the mass of the oscillating system changes, and thus the resonance frequency.

[0020] The measuring unit designed for resonance measurement excites the piezo element, e.g., with an alternating voltage whose frequency is varied over a range. Generally (also independent of the resonance measurement), the electrical measurement for monitoring mechanical integrity can be performed during operation with the pump radiation source switched on, either continuously or at intervals, or during downtimes with the pump radiation source switched off.

[0021] In a preferred embodiment, the piezo element is applied as a film or coating. Both can be advantageous in that, for example, a piezo element can be realized that is comparatively thin compared to the phosphor element. The relative contribution of the phosphor element to the mechanical behavior (in particular resonance behavior) of the composite can thus be increased and thus measurability improved. In general, the piezo element can have a thickness (taken in the thickness direction) of, for example, at least 1 µm, whereby a possible upper limit (independent of this) can be, for example, a maximum of 1 mm. The phosphor element can, for example, have a thickness of at least 5 µm and (independent of this) of, for example, no more than 5 mm.

[0022] In the structures / layer systems discussed here, the thickness direction is generally perpendicular to the incident surface, which is preferably flat. The "main incident direction" is the average of all directional vectors along which the pump radiation is incident. During this averaging process, each directional vector is weighted by the corresponding radiation area. With perpendicular irradiation, the main incident direction and the thickness direction coincide. The surface directions are perpendicular to the thickness direction, and a surface area is specified with reference to these.

[0023] In a preferred embodiment, the piezoelectric element is at least translucent (transparent), preferably transparent (see-through). A corresponding piezoelectric element can be made of transparent quartz, for example; a piezoelectric element made of zinc oxide or aluminum nitride is also possible.

[0024] The embodiments described below primarily relate to the second variant described above, in which the phosphor and the piezo element at least partially overlap in the projection plane perpendicular to the main irradiation direction. With respect to the vertical projection of the phosphor element, for example, at least 5%, 10%, 15%, or 20% of it may coincide with the vertical projection of the piezo element (cf., for example, the embodiment according to Fig. 3), whereby a further overlap of, for example, at least 40%, 60% or 80% is also possible (specified as coverage of the projection of the phosphor element).

[0025] In a preferred embodiment, the vertical projection of the phosphor element lies entirely within the vertical projection of the piezo element. The two projections can thus completely overlap, or the vertical projection of the phosphor element can be a (smaller) subset of that of the piezo element.

[0026] In a preferred embodiment, a spectrally at least partially reflective layer, which is reflective for the pump radiation and / or the conversion radiation, is arranged between the phosphor and piezo element, relative to the thickness direction. The layer can, for example, be wavelength-dependently reflective, e.g., implemented as a dichroic layer system, and reflect only the pump or conversion radiation, while transmitting the other radiation. On the other hand, however, a layer that is entirely reflective for both pump and conversion radiation can also be provided, e.g., a metal film. The latter can be particularly preferred for operation in reflection mode.

[0027] Such a reflective layer (wavelength-dependent or fully mirrored) can also generally be preferred as part of the layer system, regardless of the arrangement between the phosphor and piezo element. For example, during transmission operation, a layer that is transmissive for the pump radiation and reflective for the conversion radiation can be assigned upstream of the incident radiation surface with respect to the pump radiation; alternatively or additionally, a layer that is transmissive for the pump radiation but reflective for the pump radiation can be assigned downstream of the emitting surface with respect to the conversion radiation. During reflection operation, a full mirror is preferred on the rear side.

[0028] In a preferred embodiment, the phosphor and piezo elements are directly adjacent to each other, with a surface area. A corresponding interface extends in the surface directions. Such an interface can offer advantages, for example, in that it can help optimize mechanical coupling.

[0029] In a preferred embodiment, a carrier substrate is provided on which the phosphor and the piezo element are arranged, specifically on opposite sides thereof with respect to the thickness direction. On the one hand, operation in reflection is possible, and the carrier substrate can then be made of metal, for example as a stamped part, e.g. of aluminum. On the other hand, operation in transmission is also possible, in which case an at least translucent, preferably transparent carrier substrate is provided, e.g. made of glass or sapphire. Regardless of whether it is operated in reflection or transmission, the carrier substrate can have a larger or smaller base area (taken in the surface directions) than the piezo element; however, the two can also have the same base area (particularly in the case of a coating or covering with a film).

[0030] In a preferred embodiment, the irradiation surface is located on a rear side of the phosphor element, and the phosphor element is arranged on the piezo element with this rear side facing the piezo element (see the above information on the arrangement "on"). Operation occurs in transmission mode (translucent / transparent piezo element).

[0031] In a preferred embodiment, the piezo element is then further arranged on a carrier substrate, with its rear side facing the carrier substrate (the front side of the piezo element facing the phosphor element). The piezo element is therefore provided between the phosphor element and the carrier substrate with respect to the thickness direction. In general, the terms "front" / "rear" or "front" / "rear" refer to a direction parallel to the thickness direction, which, in particular during operation in reflection, can coincide with the direction of incidence of the pump radiation (perpendicular incidence) or can have at least one directional component thereof (tilted incidence) or, during operation in transmission with rear-side incidence, can also be exactly opposite to the direction of incidence.

[0032] In a preferred embodiment, the piezo element is arranged on the front side of the phosphor element. A substrate support can also be provided, on which the phosphor element is arranged, specifically with its rear side facing the substrate support. Generally, the piezo element arranged on the front side of the phosphor element can also completely cover the phosphor element when viewed from above.

[0033] In a preferred embodiment, the piezo element covers the front side of the phosphor element only partially, for example to a maximum of 60%, 50%, 40% or 30% (possible lower limits can be, for example, at least 10% or 20%).

[0034] In a preferred embodiment, the piezo element, which only partially covers the phosphor element, is shaped with a hole when viewed from above, through which the conversion radiation, possibly mixed with a proportion of unconverted pump radiation, is discharged ("radiating surface"). In general, particularly during operation in reflection, the phosphor element could also be irradiated on this front side through the hole in the piezo element. The piezo element preferably replicates the shape of the side edge of the phosphor element, and the hole preferably has a corresponding shape. The hole can be, for example, round, in particular circular, but also angular, in particular rectangular / square. The radiating surface or the incident surface irradiated with the pump radiation is preferably located completely within the hole, i.e. it does not overlap with the piezo element.

[0035] The invention also relates to the use of a presently disclosed irradiation device for monitoring the mechanical integrity of the phosphor element by means of electrical measurement of the piezo element (see the above details). Thus, the irradiation device can be configured for a corresponding electrical measurement, for example, by having a measuring unit with a corresponding control system, or the measurement can actually be performed during use.

[0036] The invention also relates to the use of a presently described irradiation device for lighting, in particular for motor vehicle lighting, in particular for motor vehicle exterior lighting, preferably in a headlight. The motor vehicle is preferably an automobile. The irradiation device provides a high-luminance light source that can, for example, form or support a high beam or a low beam. Monitoring the mechanical integrity also helps ensure high safety standards.

[0037] In general, however, the subject matter is of course not limited to automotive lighting, but the irradiation device can also be used, for example, in projection applications (particularly in the field of video projection), in the field of stage and / or effect lighting, as well as in medical light sources, for example in the field of endoscopy and / or microscopy. Short description of the drawings

[0038] In the following, the invention is explained in more detail using exemplary embodiments, whereby the individual features within the scope of the independent claims can also be essential to the invention in other combinations and no distinction is made in detail between the claim categories.

[0039] In detail, Fig. 1 a first converter device with piezo element in an oblique view; Fig. 2 a second converter device with piezo element in an oblique view; Fig. 3 a third converter device with piezo element in an oblique view; Fig. 4 a fourth converter device with piezo element in an oblique view; Fig. 5 a fifth converter device with piezo element in an oblique view; Fig. 6 a sixth converter device with piezo element in an oblique view; Fig. 7a a seventh converter device with piezo element in an oblique view; Fig. 7b an irradiation device with the converter device according to Fig. 7a in a side view. Preferred embodiment of the invention

[0040] Fig. Figure 1 shows a first converter device 1 with a phosphor element 2, in this case a YAG:Ce ceramic. The phosphor element 2 is arranged on a piezo element 3, in this case a quartz. The piezo element 3 has two electrical connection points 4a, b, via which it can be electrically contacted for a resonance measurement. The phosphor element 2 is attached to the piezo element 3 via an adhesive layer (not shown). Due to the mechanical coupling, the phosphor element 2 determines the oscillation behavior of the piezo element 3, specifically its resonance frequency.

[0041] During operation, for example, due to degradation processes, the phosphor element 2 may crack or break, or the phosphor element 2 may even detach completely from the piezo element 3. As a result, the resonance frequency of the oscillating system changes, which can then be determined by measuring the resonance of the piezo element 3. The piezo element 3 thus enables monitoring of the mechanical integrity of the phosphor element 2. This basic principle applies to all variants described below, without this being discussed in detail again there. In general, the same reference numerals designate parts with the same function, and reference is always made to the description of the other figures.

[0042] In the oblique view according to Fig. 1 shows a front side 5 of the phosphor element 2, which is mounted on the piezo element 3 with its opposite rear side facing the front side 6 of the piezo element 3. During reflection operation, the front side 5 of the phosphor element 2 is irradiated with pump radiation.

[0043] The piezo element 3 is according to Fig. 1 is arranged on a carrier substrate 7, with its rear side facing its front side 8. In the present case, the carrier substrate 7 is an aluminum plate, and the phosphor element 2 is operated in reflection mode, meaning that both the incident and emitted surfaces are located on the front side 5. Full or partial conversion is possible, with the latter case involving a proportion of unconverted pump radiation (blue laser light) mixed with the conversion radiation (yellow light) to form the illumination light (white light) and being discharged at the emitted surface. Optionally, a reflective layer can be provided between the phosphor element 2 and the piezo element 3, for example a silver film (not shown) deposited on the piezo element 3, which can help improve the light output.

[0044] At Fig. 2 and all figures up to Fig. 7a, the viewing direction is corresponding, so the view always falls on the front side 5 of the phosphor element 2 and (as far as visible or present) the front sides 6, 8 of the piezo element 3 and the carrier substrate 7. According to Fig. 2, the phosphor element 2 and the piezo element 3 are arranged on the front side 8 of the carrier substrate 7. In this case, the piezo element 3 is applied to the aluminum plate as a silicon nitride coating, and the phosphor element 2 is a YAG:Ce monocrystal. The piezo element 3 surrounds the phosphor element 2 in a main irradiation direction, which enables good mechanical coupling. In the variant according to Fig. 1 and the following embodiments, however, the phosphor element 2 and the piezo element 3 overlap in the main beam direction, which also results in a good mechanical coupling.

[0045] According to Fig. 3, the piezo element 3 (a silicon nitride coating) is arranged on the front side 5 of the phosphor element 2. It only partially covers this front side 5; the piezo element 3 is formed with a hole through which the phosphor element 2 is irradiated with the pump radiation (preferably during operation in reflection). However, the phosphor element 2 can also be operated in transmission, in which case the carrier substrate 7 is transparent, e.g., made of glass or sapphire. The pump radiation is then preferably supplied at the rear side (not visible in the figure), and the conversion radiation, possibly mixed with a portion of the unconverted pump radiation, is discharged at the front side 5.

[0046] According to Fig. 4, the transparent piezo element 3 covers the front side of the phosphor element 2. The piezo element 3 is applied as a foil, and the phosphor element 2 is arranged with its opposite rear side on the carrier substrate 7. The latter could be reflective, allowing the phosphor element 2 to be operated in reflection; however, a transparent carrier substrate 7 and operation of the phosphor element 2 in transmission are also possible.

[0047] In case of Fig. 5, the piezo element 3 itself forms the carrier, thus no additional carrier substrate is required. In this case, the piezo element 3 is transparent (made of quartz), and the phosphor element 2 can be operated in transmission mode (conversion radiation is dissipated from the rear, or radiation from the rear and conversion radiation is dissipated from the front).

[0048] In the variant according to Fig. 6 are piezo element 3 and fluorescent element 2 Fig. 5, but a carrier substrate 7 is additionally arranged between them, which is also transparent. Also according to Fig. 7a, a transparent carrier substrate 7 is provided between the phosphor element 2 and the piezo element 3. In this case, however, the carrier substrate 7 has a larger footprint than the piezo element 3, which can help stabilize the entire structure.

[0049] Fig. 7b shows an irradiation device with a converter device 1 according to Fig.7a, specifically in a side view. A pump radiation source 70, namely a laser diode, emits pump radiation 71, in this case blue laser light. This falls onto a rear side 72 of the phosphor element 2. At the opposite front side 5, the yellow light emitted in response to this excitation is discharged as conversion radiation mixed with a proportion of unconverted pump radiation, namely via an illumination optics (not shown). The resulting illumination light 73 is white light. However, a beam path with the opposite direction (i.e., radiation incident on the front side 5 and exit of the illumination light on the rear side) is also possible. LIST OF REFERENCE SYMBOLS 1 converter device 2 fluorescent elements 3 Piezo element 4a,b Electrical connection points 5 Front of the fluorescent element 6 Front of the piezo element 7 Carrier substrate 8 Front of the carrier substrate 70 Pump radiation source 71 Pump radiation 72 Back 73 Illumination light

Claims

[1] Irradiation device with a pump radiation source (70) for emitting pump radiation (71), a phosphor element (2) for converting the pump radiation (71) into a conversion radiation, a piezo element (3) with electrical connection points (4a, b) via which the piezo element (3) can be contacted for an electrical measurement, and a carrier substrate (7) on which the phosphor element (2) and the piezo element (3) are arranged, namely next to one another on the same side thereof, wherein the pump radiation source (70) and the phosphor element (2) are arranged relative to one another in such a way that the pump radiation (71) emitted by the pump radiation source (70) during operation strikes the phosphor element (2) with a main irradiation direction, and wherein the piezo element (3) is designed such that it encloses the phosphor element (2) as seen in the main irradiation direction, so that the mechanical integrity of the phosphor element (2) can be monitored by means of the electrical measurement of the piezo element (3). [2] Irradiation device with a pump radiation source (70) for emitting pump radiation (71), a phosphor element (2) for converting the pump radiation (71) into conversion radiation and a piezo element (3) with electrical connection points (4a, b) via which the piezo element (3) can be contacted for an electrical measurement, wherein the pump radiation source (70) and the phosphor element (2) are arranged relative to one another in such a way that the pump radiation (71) emitted by the pump radiation source (70) during operation strikes the phosphor element (2) with a main irradiation direction, wherein the phosphor element (2) and the piezo element (3) are arranged such that a vertical projection of the phosphor element (2) into a projection plane perpendicular to the main irradiation direction at least partially overlaps with a vertical projection of the piezo element (3) into the same projection plane, so that the electrical measurement of the piezo element (3) can be used to monitor the mechanical integrity of the phosphor element (2), and wherein the phosphor element (2) and the piezo element (3) are intrinsically tensioned to one another. [3] Irradiation device according to claim 1 or 2, comprising a measuring unit which is connected or connectable to the piezo element (3) for the electrical measurement via the electrical connection points (4a, b), wherein the measuring unit is configured for a resonance measurement of the piezo element (3). [4] Irradiation device according to one of the preceding claims, in which the piezo element (3) is applied as a film or as a coating. [5] Irradiation device according to one of the preceding claims, in which the piezo element (3) is at least translucent. [6] Irradiation device according to one of claims 2 to 5, excluding combinations with claim 1, in which the vertical projection of the phosphor element (2) lies entirely in the vertical projection of the piezo element (3). [7] Irradiation device according to one of claims 2 to 6, excluding combinations with claim 1, in which a layer reflective of the pump radiation (71) and / or the conversion radiation is arranged between the phosphor element and the piezo element (3). [8] Irradiation device according to one of claims 2 to 6, excluding combinations with claim 1, in which the phosphor element (2) and the piezo element (3) directly adjoin one another in a planar manner. [9] Irradiation device according to one of claims 2 to 7, excluding combinations with claim 1, with a carrier substrate (7) on which the phosphor element (2) and the piezo element (3) are arranged, namely on opposite sides of the carrier substrate (7). [10] Irradiation device according to one of claims 2 to 8, excluding combinations with claim 1, in which a rear side (72) of the phosphor element (2) is irradiated with the pump radiation (71) and the phosphor element (2) is arranged on the piezo element (3) with the rear side (72) facing the latter. [11] Irradiation device according to claim 10, comprising a carrier substrate (7) on which the piezoelectric element (3) is arranged, specifically facing the carrier substrate (7) with a rear side which is opposite a front side (6) of the piezoelectric element (3) with the phosphor element (2) thereon. [12] Irradiation device according to one of claims 2 to 8, excluding combinations with claim 1, in which a rear side (72) of the phosphor element (2) is irradiated with the pump radiation (71), wherein the piezo element (3) is arranged on a front side (5) of the phosphor element (2) opposite the rear side (72). [13] Irradiation device according to claim 12, in which, viewed in plan view, the piezo element (3) only partially covers the front side (5) of the phosphor element (2), wherein, viewed in plan view, the piezo element (3) is preferably formed with a hole through which the conversion radiation is discharged from the phosphor element (2), optionally in admixture with a proportion of unconverted pump radiation (71). [14] Use of an irradiation device according to one of the preceding claims for monitoring the mechanical integrity of the phosphor element (2) by means of the electrical measurement of the piezo element (3). [15] Use according to claim 14 for lighting, in particular for motor vehicle lighting.

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