Homogenizer comprising a light source

Abstract

The invention relates to a homogenizer having an input surface and an output surface which are incongruent to one another, at least one inclined surface extending between the input surface and the output surface. The inclined surface is corrugated. According to the invention, the homogenizer is designed as a hollow element which surrounds the LED chips (14) reflectively.

Claims

1. A homogenizer comprising an input surface and an output surface, wherein the input surface and the output surface are incongruent to each other, wherein between the input surface (12) and the output surface (22) at least an inclined surface extends, comprising a corrugation (18), wherein the homogenizer (10) is formed as an internally reflecting hollow element, wherein LED chips (14) are accommodated in the homogenizer (10), and wherein the homogenizer (10) has sensor light channels (38, 40), extending between the interior space of the hollow element and a region outside the hollow element, extending in the plane of the LED chips (14).

2. The homogenizer according to claim 1, wherein the input surface (12) is formed polygonally, and/or wherein the output surface (22) is round.

3. The homogenizer according to claim 2, wherein formed polygonally comprises squared or rectangularly and wherein round comprises formed circularly.

4. The homogenizer according to claim 1, wherein a plurality of LED chips (14) is arranged adjacent to the input surface (12), the LED chips each being cast with collecting lenses, wherein the LED chips (14) are completely accommodated in the reflector.

5. The homogenizer according to claim 1, wherein the homogenizer (10), as a hollow element, extends to a base plate (36), to which the LED chips are attached.

6. The homogenizer claim 1, wherein the output surface (22) is closed with a transparent cover plate, wherein the transparent cover plate is inserted into the homogenizer (10) and, at a wall (24) of the homogenizer facing the output surface (22), the transparent cover plate is circumferentially bonded to the homogenizer (10) with a transparent adhesive, wherein the transparent cover plate is bluntly positioned onto the output surface (22) of the homogenizer (10) and is fixed thereto.

7. The homogenizer according to claim 1, wherein on the outside of the homogenizer (10), a solid, cylindrical body is formed having a wall thickness, which, at the output side, is at least a quarter of a radius of the homogenizer, and on the input side is at least one third of the radius of the homogenizer (10) on the outside.

8. The homogenizer according to claim 1, wherein the sensor light channels (38, 40) extend to the sensors (30), and therefrom extend obliquely radially inwardly to the output surface (22) of the homogenizer.

9. The homogenizer according to claim 1, wherein the corrugation (18) comprises a multitude of ribs (20), which extend across the inner circumference of the homogenizer (10).

10. The homogenizer according to claim 9, wherein the multitude of ribs (20) comprise a number from 10 to 100.

11. The homogenizer according to claim 10, wherein the multitude of ribs (20) comprise 20.

12. The homogenizer according to claim 1, wherein ribs (20) of the corrugation (18) extend with a constant shape between the input surface (12) and the output surface (22) and/or wherein the ribs (20) of the corrugation (18) are arranged in a regular pattern, in the same distance to one another.

13. The homogenizer according to claim 1, wherein ribs (20) of the corrugation (18) extend parallel to each other, but with different shapes and/or wherein the shape of the corrugation (18), is adapted to the light wavelength or the wavelength regions transmitted by the homogenizer (10).

14. The homogenizer according to claim 13, wherein the shape of the ribs (20) is adapted to the light wavelength or the wavelength regions transmitted by the homogenizer (10).

15. The homogenizer according to claim 1, wherein the corrugation (18) of the homogenizer (10) comprises a reflective layer.

16. The homogenizer according to claim 15, wherein the reflective layer comprises a vapor-deposited reflective layer.

17. The homogenizer according to claim 1, wherein the output surface (22) of the homogenizer (10) is adjacent to an input terminal of an optical fiber and wherein output and input terminal surfaces are aligned with each other.

18. The homogenizer according to claim 1, wherein the homogenizer is formed in multiple parts, and wherein the parts of the homogenizer (10) are especially maintained to one another by snap-in connections.

19. A light curing apparatus having an homogenizer comprising, an input surface and an output surface, wherein the input surface and the output surface are incongruent to each other, wherein between the input surface (12) and the output surface (22) at least an inclined surface extends, comprising a corrugation (18), wherein the homogenizer (10) is formed as an internally reflecting hollow element, wherein LED chips (14) are accommodated in the homogenizer (10), wherein the homogenizer (10) is formed as a main reflector of the light curing apparatus and is located downstream of an optical path of a light source, and is located upstream of a light guide rod.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further advantages, details and features will result from the following description of several working examples of the invention by way of the drawings, wherein

(2) FIG. 1 is a schematic exemplary arrangement of a cut-away homogeniser comprising adjacently arranged LED chips;

(3) FIG. 2 is an embodiment according to the invention of the homogeniser according to the invention, wherein the LED chips are located in the homogeniser;

(4) FIG. 3 is a section according to the embodiment of FIG. 2;

(5) FIG. 4 is another view of the embodiment according to FIGS. 2 and 3;

(6) FIG. 5A to 5D are different possible LED arrangements for use with a homogeniser according to the invention;

(7) FIG. 6A to 6C are possible forms of the internal reflectors of the homogeniser according to the invention; and

(8) FIG. 7 is another embodiment of a homogeniser according to the invention in sectional representation.

DETAILED DESCRIPTION

(9) From FIG. 1, an exemplary homogeniser 10 as part of a light curing apparatus may be seen. Adjacent to an input surface 12 of the homogeniser 10, a plurality of LED chips 14 are arranged, which each are individually cast with a transparent casting compound 16 to form collecting lenses. In this working example, the cast LED chips 14 are spaced apart from the input surface. The input surface 12 is about squared, wherein in FIG. 1 a rectangular shape is represented, after the homogeniser 10 is represented as being cut-away.

(10) The homogeniser 10 is formed as a hollow element, comprising a corrugation 18 at its outer circumference. The corrugation 18 consists of a multitude of ribs 20, which are evenly distributed across the circumference. The ribs 20 extend, in the course of the homogeniser, along the outer circumference, i.e. from the input surface 12 to an output surface 22.

(11) In the working example represented, the ribs 20 are formed as triangular ribs. The material forming the entire wall 24 of the homogeniser 10 is corrugated, the wall 22 thus being corrugated both inside and outside.

(12) The wall 24 furthermore is provided with a mirror layer in the inside. The mirror layer may for example be realized by a vapor-deposited aluminum layer. To this, preferably a protective layer is applied, to assure constantly good reflection characteristics.

(13) The hollow element or homogeniser 10, with its wall 24, consists of polycarbonate having high surface quality and low roughness at least on the inside.

(14) In the working example represented, the output surface 22 is circular. This is suitable to supply light to the input terminal of a non-represented optical fibers. The input terminal of the optical fiber has exactly the same area as the output surface 22, with at most few percent of deviations. Thus, practically complete light transfer from the homogeniser 10 to the optical fiber is assured.

(15) In FIG. 1, light beams 25 are schematically represented, extending in a multiple reflected manner through the homogeniser 10. What is especially important is the inclined reflection at the ribs 20 on the interior side, resulting in an asymmetric and thus uncontrolled course of the light beams 25 and providing the desired homogenization.

(16) In FIG. 2, an embodiment of a homogeniser according to the invention is represented. In this embodiment, the input surface 12 is formed as a rectangular envelope curve for the LED chips 14. It is meant herewith, that the homogeniser, with the inner side of the wall 24, surrounds the multiple arrangement of LED chips 14, and comparatively closely adjacent. In this embodiment, four LED chips 14 are provided, which are symmetrically arranged. In the sectional representation, only two LED chips 14 may be seen from FIG. 7. The input surface 12 extends around the LED chips 14 and preferably such that it comparably closely abuts to the outsides of the LED chips 14.

(17) The LED chips 14 are thus accommodated in the homogeniser 10. With this embodiment, it is assured for all emitted light to be immediately guided into the homogeniser 10 and it is very likely to reflect at the ribs 20 and to be asymmetrically deflected.

(18) In the embodiment represented in FIG. 2 the wall 24 is realized from curved polycarbonate sheet welded as a tube. On the outside, the wall 24 is smooth, whereas it forms a corrugated reflector in the inside.

(19) The output surface, in turn, is circular. It has the same circumference length as the input surface 12. By way of the incongruence in shape, inclined lateral surfaces of the reflector 26, in addition to the inclination of the ribs 20 will be developed. The multi-axial inclination of the reflector 26 and the corrugation 18 support improvement of the homogeniser yields.

(20) The embodiment of the homogeniser according to FIG. 2 is sectionally represented in FIG. 3. Equal reference numbers herein, as in the other figures, will refer to equal or equivalent parts. From FIG. 3, extension of the corrugation perpendicular to both the input surface 12 and the output surface 22 may clearly be seen. It may also be seen, that the surrounding wall 24 extends angularly, thus matching the input surface to the output surface.

(21) The embodiment in FIG. 4 corresponds to the embodiment represented in FIG. 2. Additionally, it may be seen, in which way the light beams 25 will be reflected several times and extending from the input surface 12 in the direction to the output surface 22 by being deflected several times under reflection at the corrugation 18.

(22) The FIG. 5A to 5D show different possible forms of the input surface 12, which include the LED chips 14. The wall 24 and thus the reflecting hollow element 10 each extend along the straight outer sides of the cast LED chips 14. It runs obliquely between corners adjacent to each other, but offset to each other, so that the envelope curve around the cast LED chips is closely adjacent thereto.

(23) From FIG. 5A an arrangement of three LED chips 14 having equal wavelength and in one row may be seen. Spaced apart therefrom, but centrally-symmetrically arranged thereto, another larger cast LED chip is provided, which also is surrounded by the wall 24.

(24) The wall 24 according to FIG. 5A is hexagonal in shape.

(25) FIG. 5B shows an arrangement von LED chips 14, which are cast, and, in addition, sensors 30 distributed in the gaps therebetween at the outer circumference. The sensors 30 are to acquire light beams in a manner known per se, which are reflected from the surface of the respective material, for example dental material. In the represented embodiment, the sensors 30 are as well surrounded by the wall 24.

(26) In a modified embodiment, it is provided for the sensors 30 to be exempted from homogenization, and to extend the wall 24 within the sensors, but exterior of the LED chips 14. At the locations where sensors 30 are to be found, the wall 24 in this case may be somewhat indented.

(27) This embodiment is especially beneficial in a case, where the reflected light is to be acquired during the light emission of the LED chips, i.e. simultaneously and not during pulse pauses.

(28) From FIG. 5C, an asymmetric arrangement of the LED chips may be seen. Three LED chips 14 extend laterally beside to or diagonally offset to, respectively, a larger cast LED chip 14. The wall 24 of the homogeniser 10, in turn, extends in an entwinement as short as possible around the LED chips 14.

(29) From FIG. 5D, another embodiment of the arrangement of the LED chips 14 may be seen. Three LED chips 14 with a smaller casting compound extend in a triangle, and adjacent to the hypotenuse, an LED chip 14 extends, having a larger casting compound.

(30) In this case, a pentagonal arrangement of the wall 24 results, which surrounds all LED chips 14.

(31) From FIG. 6, two exemplary possible forms of the corrugation 18 may be seen. According to FIG. 6A, the corrugationand thus the ribs 20extend essentially in sinusoidal manner. A flank 32 of the rib 20 has an angle of inclination of about 45 degrees. This angle simultaneously results from the ratio of dC and dH, i.e. the period and the rib height according to FIG. 6. Both parameters may be constant, or may change around the circumference of the inner corrugation 18.

(32) While FIG. 6A and FIG. 6C showing sinusoidal corrugations, according to FIG. 6B, triangular corrugation, in turn having the angle of inclination a may be seen. The angle, in large areas, may be adapted to the requirements. In the working example represented, it is 50 degrees, so that the aperture angle of the ribs is 80 degrees. Another exemplary magnitude is a=20 degrees, corresponding to an aperture angle of 140 degrees.

(33) From FIG. 7, another embodiment of the homogeniser may be seen. The wall 24 of the homogeniser 10 is solidly formed, and the homogeniser 10 is formed in two parts, wherein the cylindrical outside of the wall 24 is interrupted by respective retaining snaps, maintaining its basic cylindrical character.

(34) The homogeniser 10, on the outside, is formed as a solid, especially essentially cylindrical body, having a wall thickness, which on the output side is at least a quarter, and on the input side is at least one third of the radius of the homogeniser (10).

(35) In this embodiment, the homogeniser 10 simultaneously acts as a homogenisier and as an reflector, after coating a mirror layer onto the ribs 18 at the interior wall of the homogeniser 10 to form a reflector and after the reflector 26 conically enlarges towards the output surface 22.

(36) The output surface 22, in this working example, is covered by a transparent cover plate 32, which is maintained with a holding ring 34 opposite of the homogeniser, and besides, is sealingly maintained.

(37) A specific feature of the embodiment according to FIG. 7 is the integration of the sensors 30, which, together with the LED chips 14, are attached on a common base plate 36. The sensors 30 thus are located in the same plane as the LED chips 14.

(38) From the interior space of the homogeniser 10 to the sensors 30 inclined sensor-light channels 38 and 40 extend, which due to their inclination, preferably capture the reflected light, for example the light reflected from a dental surface, and supplying it to the sensor 30.

(39) The angle of inclination may for example be 30 degrees, in relation to the optical axis of the homogeniser 10, but may also be only 15 or for example also 40 degrees.

(40) The sensor light channel 38 and 40 each terminates significantly spaced apart from the sensor 30. Thus, thermal separation is assured. The entire component of homogeniser and base plate is accommodated in a closed housing, so that the light provided via the sensor light channels is the only light that may reach the region of the sensor 30.

(41) In this embodiment, the homogeniser according to the invention 10 has triple function. It serves as a reflector, due to the corrugation comprising the ribs 18 as a light mixer, and simultaneously serves as a feeding element for the sensor light.