Illumination device
The lighting device enhances luminous efficacy by redirecting and converting light paths using multiple LEDs and polarizing filters, addressing the challenge of size constraints while increasing luminosity.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- AMS OSRAM INT GMBH
- Filing Date
- 2026-01-14
- Publication Date
- 2026-07-23
Smart Images
Figure EP2026050839_23072026_PF_FP_ABST
Abstract
Description
[0001] 2024PF01398 1
[0002] LIGHTING DEVICE
[0003] DESCRIPTION
[0004] In lighting devices such as lamps, spotlights, or projectors that use LEDs of different colors, it is desirable to achieve high luminous efficacy, or brightness. However, this cannot be achieved simply by increasing the light-emitting surface area of the LEDs without increasing the size of the lighting device. Increasing the size of the lighting device is often undesirable for various reasons.
[0005] The present invention is based on the objective of providing improved lighting devices.
[0006] This task is solved by the subject matter of the independent patent claims. Further developments are defined in the dependent patent claims.
[0007] In particular, a lighting device comprises a first LED capable of emitting light of a first wavelength, a second LED capable of emitting light of a second wavelength greater than the first wavelength, and a first light-splitting device capable of splitting light from the first LED into a first light path and a second light path. The first light path serves to output the light of the first wavelength from the lighting device, and the second light path directs the light of the first wavelength to the second LED. The second LED emits light of the second wavelength from the lighting device along a third light path and, upon irradiation with light of the first wavelength along the second path, magnifies the light.
[0008] Light path, the luminosity of the light of the second wavelength emitted along the third light path.
[0009] The second LED can be a conversion LED, comprising an LED that generates light of the first wavelength and a conversion element that converts the first-wavelength light generated by the second LED into the second-wavelength light emitted by the second LED. The second light path can direct the first-wavelength light emitted by the first LED onto the conversion element of the second LED. The conversion element of the second LED can be configured to convert the light from the first LED, upon reaching the conversion element, into light of the second wavelength and emit it, at least partially, along the third light path.
[0010] The lighting device may further include a filter unit arranged in the second light path, which is suitable for preventing the passage of light of the second wavelength through the filter unit.
[0011] The first light-splitting device can have reflective polarizing filters that are transparent to light of a first polarization direction and reflect light of a second polarization direction orthogonal to the first polarization direction.
[0012] The lighting device may further include polarization filters in the first light path and in the third light path, which are transparent to light of the first wavelength and light of the second wavelength with the first polarization direction.
[0013] The lighting device can also illuminate liquid crystal displays in the first light path and in the third. 2024PF01398 3
[0014] Light paths are included that are suitable to independently control the output of light of the first wavelength and light of the second wavelength.
[0015] The lighting device may further comprise first optical elements that spread the light emitted by the first LED and the light emitted by the second LED onto an illumination surface perpendicular to the direction of propagation and collimate it parallel to the direction of propagation.
[0016] The lighting device may further include second optical elements that combine the first light path and the third light path in such a way that the light of the first wavelength and the light of the second wavelength are emitted from the lighting device along the same light path.
[0017] The lighting device may further include a third LED capable of emitting light of a third wavelength, different from the first and third wavelengths. In this case, the light of the third wavelength is emitted from the lighting device along a fourth light path.
[0018] The lighting device may further comprise a second light-splitting device suitable for splitting light from the second LED onto the third light path and a fifth light path. The fifth light path directs the light of the second wavelength onto the third LED. The third wavelength is greater than the second wavelength, and the third LED, when irradiated with light of the second wavelength along the fifth light path, is suitable for increasing the luminosity of the light of the third wavelength emitted along the fourth light path. 2024PF01398 4
[0019] The third LED can have a conversion element, the fifth light path can direct the second wavelength light emitted by the second LED onto the conversion element of the third LED, and the conversion element of the third LED can be suitable for converting the light from the second LED that strikes the conversion element into light of the third wavelength and emitting it at least partially along the fourth light path.
[0020] The lighting device may further comprise a filter unit arranged in the fifth light path, which is suitable to prevent the passage of light of the third wavelength through the filter unit.
[0021] The second light-splitting device can have reflective polarizing filters that are transparent to light of a first polarization direction and reflect light of a second polarization direction orthogonal to the first polarization direction.
[0022] The lighting device may further include another polarization filter in the fourth light path, which is transparent to light of the third wavelength with the first polarization direction, and another liquid crystal display in the fourth light path, which is suitable for controlling the output of light of the third wavelength.
[0023] The lighting device may further comprise third optical elements that spread the light emitted by the third LED onto an illumination surface perpendicular to the direction of propagation and collimate it parallel to the direction of propagation. 2024PF01398 5
[0024] The lighting device may further include fourth optical elements that combine the first light path and the third light path with the fourth light path in such a way that the light of the first wavelength, the light of the second wavelength and the light of the third wavelength are emitted from the lighting device along the same light path.
[0025] The accompanying drawings serve to illustrate exemplary embodiments of the invention. The drawings depict these embodiments and, together with the description, explain them. Further exemplary embodiments and many of the intended advantages will become apparent from the detailed description below. The elements and structures shown in the drawings are not necessarily drawn to scale. Identical reference numerals refer to identical or corresponding elements and structures.
[0026] Fig. 1 shows a schematic representation of a lighting device.
[0027] Fig. 2 shows a schematic representation of a conversion LED.
[0028] Fig. 3 shows a schematic representation of another lighting device.
[0029] Fig. 4 shows a schematic representation of another lighting device.
[0030] The following detailed description refers to the accompanying drawings, which form part of the revelation and in which specific illustrations are included. 2024PF01398 6
[0031] Exemplary embodiments are shown. In this context, directional terminology such as "top," "bottom," "front," "back," "over," "on," "in front," "behind," "front," "back," etc., refers to the orientation of the figures just described. Since the components of the exemplary embodiments can be positioned in different orientations, the directional terminology serves only for explanation and is in no way restrictive.
[0032] The description of the embodiments is not restrictive, as other embodiments exist and structural or logical modifications can be made without deviating from the scope defined by the claims. In particular, elements of the embodiments described below can be combined with elements of other described embodiments, unless otherwise indicated by the context.
[0033] Fig. 1 shows a schematic representation of a lighting device 100.
[0034] The lighting device 100 comprises at least a first LED 110, a second LED 120 and a light splitting device 130.
[0035] The first LED 110 emits light of a first wavelength, while the second LED 120 emits light of a second wavelength, which is larger than the first wavelength.
[0036] In particular, the first LED 110 can be a blue LED that emits light with a wavelength or in a wavelength range of the blue visible spectrum, e.g., in the range of 450 to 500 nm or at 470 nm. The second LED 120 can be a green LED that emits light with a wavelength or in a wavelength range of the green visible spectrum. 2024PF01398 7
[0037] For example, in the range of 500 nm to 570 nm or at 535 nm. However, the first LED 110 could also be a green LED and the second LED 120 a yellow LED (wavelength in the range of 570 nm to 600 nm) or a red LED (wavelength in the range of 600 nm to 760 nm).
[0038] Although Fig. 1 shows the first LED 110 and the second LED 120 arranged parallel to each other and emitting their light in parallel, this is not strictly necessary. The LEDs 110 and 120 can also be arranged differently if required.
[0039] The light emitted by the first LED 110 is split by the first light splitting device 130 such that it leaves the first light splitting device 130 along a first light path 141 and a second light path 142.
[0040] Along the first light path 141, the light of the first wavelength emitted by the first LED 110 is directed out of the lighting device 100 to illuminate the surroundings. Along the second light path 142, the light from the first LED 110 is directed to the second LED 120.
[0041] The second LED 120 emits its light of the second wavelength along a third light path 143 to illuminate the surroundings from the lighting device 100. As shown in Fig. 1 and described later, the light of the first and second wavelengths can be emitted together from the lighting device 100. The two light beams can, for example, be superimposed to achieve color mixing. The light beams can also be modulated separately in space and time to enable the projection of colored images. However, it is also possible to modulate the two light beams at different points in the 2024PF01398 8
[0042] Lighting device 100 and / or to output in different directions.
[0043] The second LED 120 is designed such that, when irradiated with light of the first wavelength along the second light path 142, it increases the luminosity of the light of the second wavelength emitted along the third light path 143. That is, the second LED 120 is excited by the irradiation with light of the first wavelength and thereby emits light of the first wavelength with greater luminosity.
[0044] This makes it possible to change the luminosity of the different color components of the light emitted by the lighting device 100 by using portions of the light from the first LED 110 to increase the luminosity of the second LED 120. Specifically, if light from the first LED 110 is deflected from the first light path 141 by the use of optical elements, it can be directed along the second light path 142 to the second LED 120. The light deflected from the first light path 141 is therefore not lost in terms of luminosity, but can be used to increase the luminosity of the second LED 120.
[0045] Here, the second LED 120 can be a conversion LED in which the light of the second wavelength is generated by wavelength conversion. The structure of such a conversion LED is shown schematically in Fig. 2. The conversion LED has an LED 122 that generates light A of a specific wavelength that is smaller than the second wavelength, e.g., the first wavelength. This light A illuminates a conversion element 124, which is typically applied directly to the LED 122. The light A emitted by the LED 122 is
[0046] in the conversion element 124, the light B of the second wavelength generated by the second LED 120 is converted and emitted.
[0047] The conversion element 124 can be excited not only from the side of the LED 122. This allows the light of the first wavelength C to be coupled into the conversion element 124 along the second light path 142, e.g., parallel to the emission direction of the light B generated by the second LED 120. The conversion element 124 is also excited by the light C coming from the first LED 110, especially if the first LED 110 and the internal LED 122 of the second LED 120 emit light of the same wavelength. This additional excitation leads to an additional emission of light D of the second wavelength. The light C from the first LED 110 that strikes the conversion element 124 is thus (at least partially) converted by it into light D of the second wavelength and emitted along the third light path 143. In this way, the luminosity of the light emitted by the second LED 120 is increased.
[0048] Furthermore, conversion LEDs are well-known, so a further description is unnecessary. For example, green conversion LEDs are known that convert blue light from an internal LED into green light using a conversion element. This conversion element could be, for example, a cerium-doped Lu-Al crystal, applied to the internal LED as a ceramic or on a glass substrate. However, the use of other suitable materials or quantum dots is also conceivable.
[0049] The second LED 120 can also be a direct-emitting LED, meaning that the light of the second wavelength is generated in the second LED 120 without conversion. In this case as well, irradiating the second LED 120 with light from the first LED 110 can increase the luminous intensity of the second LED 120. 2024PF01398 10
[0050] Since the first wavelength is smaller than the second wavelength, irradiation with the light from the first LED 110 can cause photon-induced excitation of electrons in the semiconductor material of the second LED 120. This excitation decays by emitting light of the second wavelength, thereby increasing the luminosity of the second LED 120.
[0051] As shown in Fig. 1, the first light splitting device 130 can have reflective polarizing filters 132, 134 which are transparent to light of a first polarization direction and reflect light of a second polarization direction orthogonal to the first polarization direction.
[0052] Light of the first polarization direction is represented in the figures as a long dashed line, while light of the second polarization direction is represented as a dotted line. Light containing both polarization directions, i.e., unpolarized light, is represented as a solid line. In particular, the light emitted by the various LEDs is initially unpolarized.
[0053] As shown in Fig. 1, two reflective polarizing filters 132, 134 can be used to split the light from the first LED 110 and direct it to the second LED 120. A first reflective polarizing filter 132 is positioned in front of the first LED 110 and allows light of the first polarization direction to pass along the first light path 141, e.g., left-circularly or vertically polarized light. Light of the second polarization direction, e.g., right-circularly or horizontally polarized light, is reflected by the first reflective polarizing filter 132 along the second light path 142. The reflected light reaches the second
[0054] The light passes through the reflective polarizing filter 134 and is also reflected there. It then reaches the second LED 120.
[0055] The two reflective polarizing filters 132 and 134 serve to split the light from the first LED 110 into different polarizations and direct these light components onto different light paths. This is particularly useful when the light to be emitted along the first light path 141 is to have a specific polarization. The light component with the "wrong" polarization can then be used to excite the second LED 120, thereby partially compensating for the loss of luminous efficacy caused by splitting the light into different polarizations.
[0056] The incident polarized light of the first wavelength onto the second LED 120 does not result in the emission of polarized light of the second wavelength by the second LED 120. The light emitted by the second LED 120 with increased luminosity is unpolarized.
[0057] In the example shown in Fig. 1, two reflective polarizing filters 132, 134 were used. This is purely exemplary. A different number of reflective polarizing filters and / or other optical elements such as mirrors or dichroic mirrors can also be used to split the light of the first wavelength and direct a portion of it onto the second LED 120.
[0058] As further shown in Fig. 1, the second reflective polarizing filter 134 can preferably be used to ensure that the light of the second wavelength emitted by the second LED 120 has the first polarization direction along the third light path 143. Then the light of the second wavelength is polarized with the same polarization direction as the light 2024PF01398 12
[0059] the first wavelength is emitted. However, a different configuration can also be chosen in which the light of the second wavelength remains unpolarized or has a different polarization than the light of the first wavelength.
[0060] In the second light path 142, a filter unit 135 can also be arranged, which prevents the passage of light of the second wavelength through the filter unit 135. This ensures that light of the second wavelength is not coupled into the first light path 141 via the light splitting device 130. This guarantees that no undesired color mixing occurs along the first light path 141. Furthermore, in the case of the use of two reflective polarizing filters 132, 134 shown in Fig. 1, the filter unit 135 can ensure the absorption of the unused light of the second wavelength with the "wrong," second polarization direction.
[0061] To support the function of the reflective polarizing filters 132, 134 or to enable a light splitting device 130 without polarizing filters, a first polarizing filter 152 and a second polarizing filter 154 can be arranged in the first light path 141 and in the third light path 143, respectively, which are transparent to light of the first wavelength and light of the second wavelength, which has the first polarization direction.
[0062] The lighting device 100 can have a first liquid crystal display 162 (i.e., a liquid crystal display, LCD) in the first light path 141 and a second liquid crystal display in the third light path 143. The first liquid crystal display 162 receives light of the first wavelength and polarization direction, which is tuned to the polarization direction of the first liquid crystal display 162. This allows the first 2024PF01398 13
[0063] Liquid crystal display 162 can block or transmit light of the first wavelength in a manner known per se to produce an image in the color of the first wavelength. Similarly, the second liquid crystal display 164 can produce an image in the color of the second wavelength. In this way, the illumination device 100 can be used as a projector for colored images in a manner known per se.
[0064] The lighting device preferably comprises various optical elements. For example, by means of first optical elements, such as a first collimator 171, a first beam-shaping optic 172, a second collimator 173, and a second beam-shaping optic 174 as shown by way of example in Fig. 1, the light emitted by the first LED 110 and the light emitted by the second LED 120 can be spread out onto an illumination surface perpendicular to the direction of propagation and collimated parallel to the direction of propagation. Likewise, one (or more) first mirrors 191 can be provided to deflect the light if necessary. This ensures sufficient illumination, in particular of the liquid crystal displays 162, 164, in a manner known per se, and thereby improves the illumination / projection properties of the lighting device 100.
[0065] Likewise, by means of a second optical element, e.g., a dichroic beam splitter 181 and a projection lens 182 as shown by way of example in Fig. 1, the first light path 141 and the third light path 143 can be combined in a manner known per se such that the light of the first wavelength and the light of the second wavelength are emitted from the illumination device 100 along a common, identical light path 183. This serves in particular to realize an image projector. 2024PF01398 14
[0066] As shown schematically in Fig. 3, the lighting device 100 can also include further LEDs, e.g., a third LED 200 that emits light of a third wavelength, which differs from the first and third wavelengths. For example, the third wavelength can be a longer wavelength to produce yellow or red light if the first and second wavelengths are in the blue and green spectrum, respectively. However, the third wavelength can also be shorter than the first wavelength. For example, the third LED 200 can be a blue LED if the first LED 110 is a green LED and the second LED 120 is a yellow or red LED.
[0067] The light of the third wavelength is then emitted from the lighting device 100 along a fourth light path 144. This allows the lighting device 100 to cover the entire color space.
[0068] The lighting device 100 can then, analogous to the optical elements arranged along the first light path 141 and the third light path 143, have optical elements arranged along the fourth light path 144.
[0069] In particular, the lighting device 100 can have a further, third polarization filter 156 which is transparent to light of the third wavelength with the first polarization direction, and a further, third liquid crystal display 166 which is suitable for controlling the output of light of the third wavelength.
[0070] Third optical elements may also be provided, such as a third collimator 175 and a third beam shaping optic 176, which directs the light emitted by the third LED 200 onto an illumination surface perpendicular to the direction of propagation. 2024PF01398 15
[0071] The beams are widened and collimated parallel to the direction of propagation. Likewise, a second mirror (or more) 192 may be present if required to deflect the light from the third LED 200 along the fourth light path 144. Fourth optical elements, which may also be, for example, the dichroic beam splitter 181 and the projection lens 182, combine the first light path 141, the third light path 143, and the fourth light path 144 such that the light of the first wavelength, the light of the second wavelength, and the light of the third wavelength are emitted from the illumination device 100 along the same light path 183.
[0072] In this way, a fully functional color projector can be provided which, unlike conventional color projectors, has increased luminosity because the part of the light with the first wavelength, which has the “wrong” polarization direction for the first liquid crystal screen 162, is used to excite and increase the luminosity of the second LED 120.
[0073] To further improve the luminosity, the principle described above can also be applied to the second LED 120 and the third LED 130 if the third wavelength is greater than the second wavelength. The lighting device 100 then has a second light-splitting device 210 that splits light from the second LED 120 onto the third light path 143 and a fifth light path 145. The light of the second wavelength is directed along the fifth light path 145 to the third LED 200. Illumination with light of the second wavelength along the fifth light path 145 increases the luminosity of the light of the third wavelength emitted along the fourth light path 144. 2024PF01398 16
[0074] For example, the third LED 200 can have a (second) conversion element 220, as schematically shown in Fig. 4. The light from the second LED 120 is then directed onto the conversion element 220 of the third LED 200. In the conversion element 220 of the third LED, the light from the second LED 120 that strikes the conversion element 220 is (at least partially) converted into light of the third wavelength and can be emitted along the fourth light path 144.
[0075] The third LED 200 can be a conversion LED, as schematically described above with reference to Fig. 2. Alternatively, the third LED 200 can be a direct-emitting LED onto which the conversion element 220 has been applied. The conversion element 220 is then designed such that it is (largely) transparent to light of the third wavelength, but absorbs light of the second wavelength and converts it into light of the third wavelength. For a yellow LED, the conversion element 220 can, for example, be or have a cerium-doped Yt-Al crystal. For a red LED, for example, (Ca, Sr)A1S1N3:EU2+ or Sr[L1A13N4]:Eu2+ can be used. However, the use of other materials is also possible.
[0076] Furthermore, for the third LED 200, direct excitation of electrons via the band gap of the semiconductor material of the third LED 200 can also occur through the incident light of the second wavelength, since this is smaller than the third wavelength.
[0077] As shown by way of example and schematically in Fig. 4, the second light splitting device 210 can also have reflective polarizing filters 134, 216 which are transparent to light of a first polarization direction and which the light2024PF01398 17
[0078] reflect a second polarization direction that is orthogonal to the first polarization direction.
[0079] In particular, the light of the second wavelength can be split at the second reflective polarizing filter 134 into a transmitted component of the first polarization direction and a component of the second polarization direction reflected along the fifth light path 145. The reflected component is then directed to the third LED 200, e.g., by means of a dichroic mirror 212, which is transparent to the first wavelength and reflects the light of the second wavelength, a further (third) mirror 214, and a third reflective polarizing filter 216 arranged in the fourth light path 144. The third reflective polarizing filter 216 also serves to split the light of the third wavelength into the first and second polarization directions.
[0080] To avoid backscattering of the third wavelength light into the third light path 143, a filter unit 215 can be provided in the fifth light path 145, which prevents the passage of third wavelength light through the filter unit 215.
[0081] The configuration shown in Fig. 4 is purely exemplary. Any other optical components can also be used to split the light of the second wavelength into its polarization components and direct one of them onto the third LED 200. The crucial point is that by repeatedly directing light with the "wrong" polarization direction for the intended application onto an LED emitting lower-energy light, a reduction in luminous intensity due to the separation of the 2024PF01398 18
[0082] The "incorrect" polarization direction can be mitigated or even completely compensated.
[0083] This particularly enables the provision of high-luminosity projectors.
[0084] Although specific embodiments have been illustrated and described herein, those skilled in the art will recognize that the specific embodiments shown and described can be replaced by a multitude of alternative and / or equivalent embodiments without departing from the scope of protection of the invention. The application is intended to cover any adaptations or variations of the specific embodiments discussed herein. Therefore, the invention is limited only by the claims and their equivalents. 2024PF01398 19
[0085] REFERENCE MARK LIST
[0086] 100 lighting device
[0087] 110 first LED
[0088] 120 second LEDs
[0089] 122 LED
[0090] 124 first conversion element
[0091] 130 first light splitting device
[0092] 132 First reflective polarizing filter 134 Second reflective polarizing filter 135 First filter unit
[0093] 141 first light path
[0094] 142 second light path
[0095] 143 third light path
[0096] 144 fourth light path
[0097] 145 fifth light path
[0098] 152 first polarization filter
[0099] 154 second polarization filter
[0100] 156 third polarization filter
[0101] 162 first liquid crystal display
[0102] 164 second liquid crystal display
[0103] 166 third liquid crystal display
[0104] 171 first collimator
[0105] 172 first beam shaping optics
[0106] 173 second collimator
[0107] 174 second beam shaping optics
[0108] 175 third collimator
[0109] 176 third beam shaping optics
[0110] 181 dichroic beam combiner
[0111] 182 Projection lens
[0112] 183 shared light path
[0113] 191 first mirror
[0114] 192 second mirror
[0115] 200 third LED2024PF01398 20
[0116] 210 second light splitting device 212 dichroic mirror
[0117] 214 third mirror
[0118] 215 second filter unit
[0119] 220 second conversion element
Claims
2024PF01398 21 REQUIREMENTS 1. Lighting device ( 100 ) , comprising a first LED ( 110 ) which is suitable to emit light of a first wavelength; a second LED ( 120 ) which is suitable to emit light of a second wavelength which is greater than the first wavelength; a first light splitting device (130) which is suitable for splitting light from the first LED (110) onto a first light path (141) and a second light path (142); wherein the first light path (141) serves to output the light of the first wavelength from the illumination device (100); the second light path ( 142 ) directs the light of the first wavelength to the second LED ( 120 ); the second LED (120) is suitable for emitting light of the second wavelength along a third light path (143) from the lighting device (100); and the second LED ( 120 ) is suitable to increase the luminosity of the light of the second wavelength emitted along the third light path ( 143 ) when irradiated with light of the first wavelength along the second light path ( 142 ).
2. Lighting device (100) according to claim 1, wherein the second LED (120) is a conversion LED comprising an LED (122) generating light of the first wavelength and a conversion element (124) that converts the light of the first wavelength generated in the second LED (120) into the light of the second wavelength emitted by the second LED (120); the second light path (142) directs the light of the first wavelength emitted by the first LED (110) onto the conversion element (124) of the second LED (120); and2024PF01398 22 the conversion element ( 124 ) of the second LED ( 120) is suitable to convert the light of the first LED ( 110) which strikes the conversion element ( 124) into light of the second wavelength and to emit at least partially along the third light path.
3. Lighting device ( 100) according to one of the preceding claims, further comprising a filter unit (135) arranged in the second light path (142) which is suitable to prevent the passage of light of the second wavelength through the filter unit (135).
4. Lighting device ( 100) according to one of the preceding claims, wherein the first light splitting device ( 130) comprises reflective polarizing filters ( 132, 134 ) which are transparent to light of a first polarization direction and which reflect light of a second polarization direction orthogonal to the first polarization direction.
5. Lighting device (100) according to claim 4, further comprising Polarization filters ( 152, 154 ) in the first light path ( 141 ) and in the third light path ( 143 ) which are transparent to light of the first wavelength and light of the second wavelength with the first polarization direction.
6. Lighting device (100) according to one of claims 4 or 5, further comprising Liquid crystal displays (162, 164) in the first light path (141) and in the third light path (143) that are suitable for independently controlling the output of light of the first wavelength and of light of the second wavelength. 2024PF01398 23 7. Lighting device ( 100) according to one of the preceding claims, further comprising first optical elements ( 171, 172, 173, 174 ) which spread the light emitted by the first LED ( 110) and the light emitted by the second LED ( 120) onto an illumination surface perpendicular to the direction of propagation and collimate it parallel to the direction of propagation.
8. Lighting device ( 100) according to one of the preceding claims, further comprising second optical elements ( 181, 182 ) which combine the first light path ( 141 ) and the third light path ( 143) in such a way that the light of the first wavelength and the light of the second wavelength are emitted from the illumination device ( 100) along the same light path ( 183 ).
9. Lighting device ( 100) according to one of the preceding claims, further comprising a third LED (200) which is suitable for emitting light of a third wavelength which differs from the first wavelength and the third wavelength; wherein the light of the third wavelength is emitted along a fourth light path ( 144 ) from the lighting device ( 100).
10. Lighting device ( 100) according to claim 9, further comprising a second light-splitting device (210) suitable for splitting light from the second LED (120) onto the third light path (143) and a fifth light path (145); wherein the fifth light path (145) directs the light of the second wavelength onto the third LED (200); 2024PF01398 24 the third wavelength is larger than the second wavelength; and the third LED (200) is suitable to increase the luminosity of the light of the third wavelength emitted along the fourth light path ( 144) when irradiated with light of the second wavelength along the fifth light path ( 145).
11. Lighting device ( 100) according to claim 10, wherein the third LED (200) has a conversion element (220 ); the fifth light path ( 145) directs the second wavelength light emitted by the second LED ( 120) onto the conversion element (220) of the third LED (200); and the conversion element (220) of the third LED (200) is suitable to convert the light from the second LED ( 120) that strikes the conversion element (220) into third wavelength light and to emit at least part of it along the fourth light path ( 144 ).
12. Lighting device ( 100) according to one of claims 10 or 11, further comprising a filter unit (215) arranged in the fifth light path ( 145) which is suitable to prevent the passage of light of the third wavelength through the filter unit (215).
13. Lighting device ( 100) according to one of claims 10 to 12, wherein The second light-splitting device (210) comprises reflective polarizing filters (134, 216) that are transparent to light of a first polarization direction and reflect light of a second polarization direction orthogonal to the first polarization direction. 2024PF01398 25 14. Lighting device ( 100) according to one of claims 9 to 13, further comprising a further polarization filter ( 156 ) in the fourth light path ( 144 ) which is transparent to light of the third wavelength with the first polarization direction; and a further liquid crystal display ( 166) in the fourth light path, which is suitable for controlling the output of light of the third wavelength.
15. Lighting device ( 100) according to one of claims 9 to 14, further comprising third optical elements ( 175, 176 ) which spread the light emitted by the third LED (200) onto an illumination surface perpendicular to the direction of propagation and collimate it parallel to the direction of propagation.
16. Lighting device ( 100) according to one of claims 9 to 15, further comprising fourth optical elements ( 181, 182 ) which combine the first light path ( 141 ) and the third light path ( 143 ) with the fourth light path ( 144 ) such that the light of the first wavelength, the light of the second wavelength and the light of the third wavelength are emitted from the illumination device ( 100) along the same light path ( 183 ).