Wavelength conversion of primary light by means of a conversion body

Abstract

Wavelength conversion of primary light by means of a conversion body, a conversion device and an illumination apparatus is described herein. In some aspects, a conversion body may include a main body containing a wavelength-converting phosphor. The main body may have an irradiation surface to be irradiated by primary light. The conversion body may further include at least one conduction tract mounted on the main body outside the irradiation surface. The at least one conduction track may be electrically conductive in accordance with some aspects.

Claims

1. A conversion body, comprising: a main body comprising a wavelength-converting phosphor, the main body having an irradiation surface to be irradiated by primary light; at least one conduction track mounted on the main body outside the irradiation surface, the at least one conduction track being electrically conductive; and an evaluation device connected to the at least one conduction track, the evaluation device being configured to detect a crack in the main body based on a change in an electric property of the at least one conduction track.

2. The conversion body of claim 1, wherein the main body is a phosphor platelet, and the irradiation surface is centered on a flat side of the main body.

3. The conversion body of claim 2, wherein at least one edge-side conduction track extends along at least a portion of an edge of the flat side comprising the irradiation surface.

4. The conversion body of claim 3, wherein the at least one edge-side conduction track extends along an entire length of the edge of the flat side comprising the irradiation surface.

5. The conversion body of claim 3, wherein the at least one edge-side conduction track extends along at least one mechanical damage site introduced at the edge of the flat side.

6. The conversion body of claim 4, wherein at least one other conduction track extends between the at least one edge-side conduction track and the irradiation surface.

7. The conversion body of claim 6, wherein at least one additional conduction track is offset from the at least one edge-side conduction track by a distance.

8. The conversion body of claim 1, wherein the main body consists of a wavelength-converting ceramic.

9. The conversion body of claim 1, wherein the at least one conduction track comprises aluminum.

10. The conversion body of claim 1, wherein the at least one conduction track is a wire embedded in the main body, and the wire comprises tungsten.

11. The conversion body of claim 1, wherein the at least one conduction tract has a width between 100 microns (m) and 750 m, and the at least one conduction tract has a thickness between 100 nanometers (nm) and 300 nm.

12. The conversion body of claim 1, wherein a diameter of the main body is between one millimeter to two millimeters.

13. The conversion body of claim 1, wherein the at least one conduction track comprises copper or tin.

14. The conversion body of claim 1, wherein the at least one conduction track is a surface-mounted conductor disposed on the main body.

15. The conversion body of claim 1, wherein the main body comprises a fluorescent phosphor.

16. A conversion device, comprising: at least one conversion body including a main body comprising a wavelength-converting phosphor, the main body having an irradiation surface to be irradiated by primary light, and at least one conduction track mounted on the main body outside the irradiation surface, the at least one conduction track being electrically conductive; and an evaluation device connected to the at least one conduction track, the evaluation device being configured to detect a crack in the main body based on a change in an electric property of the at least one conduction track.

17. The conversion device of claim 16, wherein the evaluation device is further configured to detect a crack in the main body based on a breakage of the at least one conduction track.

18. The conversion device of claim 17, wherein the main body is a phosphor platelet, the irradiation surface is centered on a flat side of the main body, at least one edge-side conduction track extends along an entire length of an edge of the flat side comprising the irradiation surface, at least one other conduction track extends between the at least one edge-side conduction track and the irradiation surface, and the evaluation device is further configured to trigger at least one first action upon detecting a breakage in the at least one edge-side conduction track and trigger a deactivation of an irradiation of the main body upon detecting a breakage of the at least one additional conduction track.

19. The conversion device of claim 16, wherein the conversion device is a part of an illumination apparatus.

20. An illumination apparatus, comprising: at least one conversion device including at least one conversion body containing a main body comprising a wavelength-converting phosphor, the main body having an irradiation surface to be irradiated by primary light and at least one conduction track mounted on the main body outside the irradiation surface, the at least one conduction track being electrically conductive, and an evaluation device connected to the at least one conduction track, the evaluation device being configured to detect a crack in the main body based on a change in an electric property of the at least one conduction track; and at least one semiconductor primary light source for irradiating the irradiation surface of the main body associated therewith, wherein the evaluation device is linked to the at least one semiconductor primary light source.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The properties, features and advantages of the present disclosure described above and the manner in which these are achieved, will become clearer and more comprehensible in conjunction with the following description of an embodiment, which is explained in more detail in connection with the drawings. For clarity of exposition, identical or equivalent functional elements are labeled with the same reference numeral.

(2) FIG. 1 shows a plan view of an illumination apparatus having a conversion body according to a first embodiment;

(3) FIG. 2 shows a plan view of a conversion body according to a second embodiment; and

(4) FIG. 3 shows a plan view of a conversion body according to a third embodiment.

DETAILED DESCRIPTION

(5) FIG. 1 shows a plan view of an illumination apparatus B1 with a conversion device E1, which has a conversion body 1 according to a first embodiment.

(6) The conversion body 1 has a circular-disc-shaped main body 2 formed of wavelength-converting ceramic, which can also be designated as a circular conversion ceramic platelet. Centrally on the front side of the main body 2 shown, an imaginary irradiation surface 3 is provided, which is to be irradiated withfor example blueprimary light P. There should be little or no primary light P incident outside the irradiation area 3.

(7) An electrically conductive conduction track is applied on at least the front side of the main body 2 shown, in the form of an, e.g., sputtered-on conductor track 4 made of aluminum. The conductor track 4 is almost completely annular in shape and has an outer contour that extends up to an edge A of the main body 2. The conductor track 4 therefore extends almost completely along the edge A. Only one gap-like interruption 5 is present where the conductor track 4 is split or interrupted, in order to prevent a short circuit when an electric current flows.

(8) The conductor track 4 has a width of approximately 200 microns and a thickness of approximately 200 nanometers (nm). A diameter of the main body 2 is approximately one to two millimeters (mm).

(9) An evaluation device G is connected to the open ends of the conductor track 4 of the conversion device E1, which has a DC voltage source U and a series resistor R1. The series resistor R1 is connected to the DC voltage source U in series with the conductor track 4. The voltage present at the series resistor R1 can be sensed using a measuring device M associated with the evaluation device G. The voltage measurements determined by the measuring device M can be used by a control device C connected to the measuring device M to activate a primary light source in the form of at least one laser L. The control device C can either be part of the evaluation device G, or a stand-alone component. The control device C and the evaluation device G can also be integrated into a component, e.g., into a control device C with evaluation function. The conversion device E1, including the evaluation device G and the conversion body 1, can be in the form of a module.

(10) In one configuration, the illumination apparatus B1 can be operated as follows:

(11) The control device C activates the at least one laser L in such a way that the laser irradiates the illumination surface 3 with primary light P of a standard radiant power. If the main body 2 is free of cracks, the conductor track 4 is also crack-free and, for practical purposes, has an electrical resistance R20. The measuring device M then measures the voltage U generated by the DC voltage source across the series resistor R1 as the measuring voltage Um, so that for practical purposes, U=Um.

(12) If a crack (not illustrated) is initiated at the edge A, it extends into the inside of the main body 2 and generates an analogous crack or a corresponding discontinuity in the conductor track 4. If the crack has only partially spread into an area below the conductor track 4, the conductor track 4 starts to crack, but is not yet fully interrupted. The resistance R2 increases to a measurable finite value due to the resulting cross-sectional constriction. The measuring device M then measures a measuring voltage Um across the series resistor R1 with a value Um=R1/(R1+R2).Math.U. In one variant, the control device C can at this point already reduce a radiation power of the at least one laser L, to slow down or even initially prevent any further crack propagation.

(13) If the crack has fully crossed the main body 2 underneath the conductor track 4 and thereby also cut through or interrupted the conductor track 4, then the measuring device M measures a value Um=0, which can be very reliably detected. In one variant, the control device C can then already (even further) reduce a radiation power of the at least one laser L, to slow down or even initially prevent any further crack propagation. It can, in particular, reduce the radiant power of the primary light P to zero (in particular turn off or disable the laser L), in order to reliably prevent a further crack propagation.

(14) This protective function is used, in particular, to prevent an escape of concentrated primary light P from the illumination apparatus B1 due to a damaged main body 2.

(15) FIG. 2 shows a plan view of an illumination apparatus B2 having a conversion body 11 according to a second embodiment. The conversion body 11 has two annular conductor tracks 12 and 13, arranged concentrically on the main body 2, of which one conductor track 12 is an edge-side conductor track similar to the conductor track 4. The conductor track 12 can be so thin that in the event of any crack beginning to form especially at the edge of the main body 2, its fracture can be practically measured and evaluated. The other conductor track 13 runs between the edge-side conductor track 12 and the irradiation surface 3. The other conductor track 13 is designed, like conductor track 12, to have an annular form and therefore a similar shape thereto. The narrow discontinuities 14 and 15 of the conductor tracks 12 and 13 are offset at an angle to each other, in order to prevent a crack from propagating through both discontinuities 14 and 15. Electrical connection cables (not shown) between the measuring device M and the conductor track 13 can be advantageously routed through the discontinuity 14 of the edge-side conductor track 12, for example in the form of thin, narrow, conductor track-like aluminum coatings or optically transparent ITO conductor tracks.

(16) In an extension, it is provided that electrical properties of the conductor tracks 12 and 13 can be sensed in a similar manner to the conductor track 4, for example, a respective measuring voltage Um can be measured, in particular, individually for each one of the two conductor tracks 12 and 13. To this end, two evaluation devices G can be present, but which can also be at least partially integrated, e.g., by using a common DC voltage source U. A conversion device E2 can then include the conversion body 11 and both evaluation devices 9.

(17) The control device C can then use each measured voltage Um for activating the at least one laser L.

(18) The illumination apparatus B2 can then be operatedin particular, in the same way as the illumination apparatus of B1 FIG. 1in a configuration as follows:

(19) A control device C activates the at least one laser L in such a way that the laser irradiates the illumination surface 3 of the main body 2 with primary light P of a standard radiant power.

(20) If the main body 2 is free of cracks, the conductor tracks 12 and 13 are also crack-free and, for practical purposes, have an electrical resistance R20. The (individual or joint) measuring device M then measures the DC voltage U generated by the (individual or joint) DC voltage source U across a respective series resistor R1 as the measured voltage Um.

(21) If a crack (not shown) is triggered at the edge A of the main body 2, this crack spreads into the interior of the main body 2 and first cuts through the edge-sided conductor track 12, so that this is interrupted. The control device C can at this point reduce a radiant power of the at least one laser L, to slow down or even initially prevent any further crack propagation.

(22) With the splitting of the edge-side conductor track 12, the control device C can also trigger other actions, for example, issuing a warning to a user of the illumination apparatus B2 and/or informing a service entity (e.g., a workshop).

(23) If the crack has crossed the main body 2 below the conductor track 13 and thereby also cut through or interrupted the conductor track 13, the control device C can then, for example, reduce the radiant power of the primary light P to zero (in particular, switch off or deactivate the laser L), in order to reliably prevent any further crack propagation and/or prevent irradiation of an already cracked irradiation surface 3.

(24) This protective function is also used to prevent an escape of concentrated primary light P from the illumination apparatus B2 due to a damaged main body 2.

(25) FIG. 3 shows a plan view of an illumination apparatus B3, which has a conversion device E3 with a conversion body 21 according to a third embodiment.

(26) The illumination apparatus B3 can be operated, for example, similarly to the illumination apparatus B1. However, the conductor track 22 is then not designed to run circumferentially around the edge, but only along a short section or sector (e.g., of not more than 45, in particular of not more than 20, and in particular of not more than 10, of the total circumference or edge A). In order, nevertheless, to be able to reliably detect a mechanical overloading of the main body 2 by a thermally induced edge-side tensile stress due to irradiation of the irradiation surface 3 with the primary light P, on the section of the edge A, on which the conductor track 22 is located, a selectively applied, predefined damage site in the form of a (micro-)notch K is present. If the tensile stress at the edge A reaches an at least roughly adjustable threshold, then an internally oriented crack is formed at the notch K, which can be detected by a break etc. in the conductor track 22.

(27) A plurality of conductor tracks 22 with respective notches K can also be provided, for example, evenly distributed around the edge A or the circumference.

(28) Although the present disclosure has been illustrated and described in greater detail by means of the embodiments shown, the present disclosure is not restricted thereto and other variations can be derived therefrom by the person skilled in the art without departing from the scope of protection of the present disclosure.

(29) Thus, instead of a conductor track made of aluminum a track made of another metal such as copper or tin can also be used. Also, instead of a conductor track it is possible to provide a wire, in particular made from or with tungsten, which is embedded in the body.

(30) The shape of main body and the conductor track(s) can also be oval, cornered (for example, rectangular, in particular square) and generally free-form.

(31) In addition, more than one additional conductor track can also be provided.

(32) In general, the word a, one can mean a singularity or a plurality, in particular in the sense of at least one or one or more, and so on, except where this is explicitly excluded, for example by the expression exactly one, etc.

(33) Also, a numerical value can include both exactly the specified number and also the standard tolerance range, unless this is explicitly excluded.

REFERENCE NUMERALS

(34) 1 conversion body 2 main body 3 irradiation surface 4 conductor track 5 discontinuity 11 conversion body 12 edge-side conductor track 13 additional conductor track 14 discontinuity of the edge-side conductor track 15 discontinuity of the additional conductor track 21 conversion body 22 conductor track A edge of the main body B1 illumination apparatus B2 illumination apparatus B3 illumination apparatus C control device E1 conversion device E2 conversion device E3 conversion device G evaluation device K notch L laser M measurement device P primary light R1 series resistor R2 resistance of the conductor track U DC voltage source Um measured voltage