Lighting device and method for generating light by means of a wavelength conversion arrangement and a band-stop filter, and method for providing a band-stop filter

• US 20150124430A1
• Filed: 10/31/2014
• Published: 05/07/2015
• Est. Priority Date: 11/05/2013
• Status: Active Grant

• Current Assignee: Coretronic Corporation
• Original Assignee: OSRAM GmbH (Ams-Osram AG)
• Inventors: Mehl, Oliver
• Granted Patent: US 9,885,864 B2
• Time in Patent Office: Days
• US Class Current: 362/84
• CPC Class Codes: F21V 9/45 by adjustment of photoluminescent elements
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• CPC Class Codes: F21Y 2115/30 Semiconductor lasers
• CPC Class Codes: G02B 26/008 in the form of devices for effecting sequential colour changes, e.g. colour wheels

Abstract

The invention proposes a lighting device (1) comprising a wavelength conversion arrangement (12) and a static band-stop filter (14). The wavelength conversion arrangement (12) comprises two wavelength conversion elements, which can be excited to emit conversion light by means of excitation radiation emitted by an excitation source (2). In order to increase the color space which is addressable by means of the two wavelength conversion elements, with the aid of the band-stop filter (14) the shorter dominant wavelength of the conversion light of both wavelength conversion elements is shortened and the longer dominant wavelength is lengthened. For this purpose, the peak wavelength of the band-stop filter (14) is chosen such that it lies between the two dominant wavelengths of the conversion light emitted by the two wavelength conversion elements. The use of a static band-stop filter (14) designed in this way makes it possible to dispense with separate filter elements for each wavelength conversion element. If the wavelength conversion arrangement is designed as a phosphor wheel (12), in particular a separate filter wheel to be synchronized with the phosphor wheel can be dispensed with.

Claims

1. A lighting device for generating light by means of a wavelength conversion arrangement, comprising

an excitation radiation source, which is designed to emit excitation radiation, and

a wavelength conversion arrangement, which comprises at least one first wavelength conversion element and one second wavelength conversion element, which wavelength conversion arrangement is arranged in such a way that excitation radiation emitted by the excitation radiation source can be radiated at least indirectly onto the first wavelength conversion element and onto the second wavelength conversion element,

wherein the first wavelength conversion element is designed to convert excitation radiation into light having a first spectrum and a first dominant wavelength, and

wherein the second wavelength conversion element is designed to convert excitation radiation into light having a second spectrum and a second dominant wavelength, wherein the second dominant wavelength is longer than the first dominant wavelength,

characterized in that

the lighting device furthermore comprises at least one band-stop filter arranged in such a way that light emitted by the first wavelength conversion element and the second wavelength conversion element can be radiated at least partly and at least indirectly onto the band-stop filter, wherein the band-stop filter is designed to filter the light emitted by the wavelength conversion elements and radiated onto the band-stop filter in such a way that the first dominant wavelength is shortened and the second dominant wavelength is lengthened.

2. The lighting device as claimed in claim 1, wherein the first wavelength conversion element is designed in such a way that the first dominant wavelength is in a green or yellow-green spectral range.

3. The lighting device as claimed in claim 1, wherein the second wavelength conversion element is designed in such a way that the second dominant wavelength is in a red or yellow-red spectral range.

4. The lighting device as claimed in claim 1, wherein the band-stop filter is designed in such a way that it blocks a yellow spectral range.

5. The lighting device as claimed in claim 1, wherein the band-stop filter has a peak wavelength in the range of between 555 and 605 nm, in particular between 565 and 585 nm.

6. The lighting device as claimed in claim 1, wherein the band-stop filter has an FWHM filter width in the range of between 5 and 25 nm, in particular between 10 and 20 nm.

7. The lighting device as claimed in claim 1, wherein the band-stop filter is designed as a static filter.

8. The lighting device as claimed in claim 1, wherein the wavelength conversion arrangement is designed as a phosphor wheel, which is rotatable about a rotation axis of the phosphor wheel, wherein the first wavelength conversion element is arranged at least in a segment of a ring-shaped region of the phosphor wheel running around the rotation axis of the phosphor wheel, and wherein the second wavelength conversion element is arranged at least in a second segment of the or a further region running in a ring-shaped fashion around the rotation axis of the phosphor wheel.

9. The lighting device as claimed in claim 8, wherein the phosphor wheel has a region that is transmissive to the excitation radiation in at least one third segment of the or a further region running in a ring-shaped fashion around the rotation axis.

10. The lighting device as claimed in claim 8, wherein the lighting device is configured in such a way that excitation radiation emitted by the excitation radiation source, at least indirectly, during a rotation of the phosphor wheel, can be radiated sequentially onto each segment of the region of the phosphor wheel running in a ring-shaped fashion around the rotation axis.

12. A method for providing a band-stop filter for use in a lighting device as claimed in claim 1, characterized by the following method step:

selecting the peak wavelength and the FWHM filter width of the band-stop filter in such a way that the band-stop filter reduces the dominant wavelength of the wavelength-converted light having the first spectrum and increases the dominant wavelength of the wavelength-converted light having the second spectrum.

13. The method as claimed in claim 12 comprising the following additional method step:

selecting the peak wavelength and the FWHM filter width of the band-stop filter in such a way that the band-stop filter reduces the total luminous flux of the wavelength-converted light having the first spectrum and of the wavelength-converted light having the second spectrum to not less than 75%, in particular not less than 80%.

14. The method as claimed in claim 12 comprising the following additional method step:

selecting the peak wavelength of the band-stop filter in such a way that the band-stop filter increases the color temperature of the mixed light, which is mixed from the wavelength-converted light having the first spectrum and the wavelength-converted light having the second spectrum and, if appropriate, one or more further colored light portions, in relation to the unfiltered mixed light.

11. A method for generating light by means of a wavelength conversion arrangement, which comprises at least two wavelength conversion elements, comprising the following method steps:

providing a first wavelength conversion element, which, upon absorbing excitation radiation, converts the latter into light having a first spectrum and a first dominant wavelength,

providing a second wavelength conversion element, which, upon absorbing excitation radiation, converts the latter into light having a second spectrum and a second dominant wavelength, wherein the first dominant wavelength is shorter than the second dominant wavelength,

radiating excitation radiation onto the first wavelength conversion element,

radiating excitation radiation onto the second wavelength conversion element,

characterized by the following further method step;

providing a band-stop filter, which filters the light converted by the wavelength conversion elements in such a way that the first dominant wavelength is shortened and the second dominant wavelength is lengthened.