# US 2013/0155643 A1 · Daylight illumination apparatus > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2013/0155643 A1 - Document ID: US20130155643A1 - Status: Published application - Kind: A1 - Application number: 13/819,855 - Filed: 2011-08-26 - Published: 2013-06-20 - Earliest claimed: 2010-09-02 - Assignees: Koninklijke Philips Electronics N.V. - Inventors: Jörg Meyer; Martinus P. J. Peeters; René T. Wegh; Ramon P. Van Gorkom; Rifat A. M. Hikmet - Web page: https://patentgrep.com/patent/US20130155643A1 ## CPC - F21S 11/007: {characterised by the means for transmitting light into the interior of a building} - F21S 19/005: {Combining sunlight and electric light sources for indoor illumination} - F21V 7/30: the coatings comprising photoluminescent substances - F21V 9/02: for simulating daylight (F21V9/04, F21V9/06 take precedence) - F21V 9/32: characterised by the arrangement of the photoluminescent material - F21V 13/14: the elements being filters or photoluminescent elements, reflectors and refractors - G02B 6/0008: {the light being emitted at the end of the fibre} - F21V 9/14: for producing polarised light - F21Y 2115/10: Light-emitting diodes [LED] - F21S: NON-PORTABLE LIGHTING DEVICES; SYSTEMS THEREOF; VEHICLE LIGHTING DEVICES SPECIALLY ADAPTED FOR VEHICLE EXTERIORS - F21V: FUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS - F21Y: INDEXING SCHEME ASSOCIATED WITH SUBCLASSES F21K, F21L, F21S and F21V, RELATING TO THE FORM OR THE KIND OF THE LIGHT SOURCES OR OF THE COLOUR OF THE LIGHT EMITTED ## Abstract The invention relates to a daylight illumination apparatus. A daylight collector (3) collects daylight (4), which is guided to an illumination location to be illuminated along an optical path by a light guide (5), wherein the daylight is absorbed by the light guide. A photoluminescent material (6, 8) is arranged within the optical path and emits photoluminescent light that compensates for the absorption of the daylight by the light guide. Absorption losses of the daylight can therefore effectively be compensated, without necessarily needing, for example, an active compensation light source. This allows providing compensated day-light illumination in a technically relatively simple way. ## Claims ### Claim 1 A daylight illumination apparatus comprising: a daylight collector for collecting daylight, a light guide for guiding the daylight to an illumination location to be illuminated along an optical path, wherein the daylight is absorbed by the light guide, a photoluminescent material for emitting photoluminescent light for illuminating the illumination location when the photoluminescent material is illuminated by the daylight, wherein the photoluminescent material is arranged within the optical path and adapted such that the photoluminescent light compensates for the absorption of the daylight by the light guide. ### Claim 2 (depends on 1) The daylight illumination apparatus as defined in claim 1, wherein the light guide absorbs light of a first spectral part of the daylight more than light of a second spectral part of the daylight and wherein the photoluminescent material is adapted to emit photoluminescent light having a wavelength in the first spectral part. ### Claim 3 (depends on 1) The daylight illumination apparatus as defined in claim 1, wherein the light guide comprises an optical fiber having an in-coupling site for coupling the daylight into the optical fiber arid an out-coupling site for coupling the daylight out of the optical fiber, wherein the photoluminescent material is located at the out-coupling site of the optical fiber. ### Claim 4 (depends on 1) The daylight illumination apparatus as defined in claim 1, further comprising an active compensation light source for generating compensation light for further compensating for the absorption of the daylight by the light guide. ### Claim 5 (depends on 4) The daylight illumination apparatus as defined in claim 4, wherein the active compensation light source is adapted to generate compensation light having a spectral distribution being similar to the spectral distribution of direct natural daylight. ### Claim 6 (depends on 4) The daylight illumination apparatus as defined in claim 4, further comprising: an intensity determination unit for determining the intensity of the light at the illumination location, and a control unit for cont oiling the active compensation light source depending on the determined intensity. ### Claim 7 (depends on 1) The daylight illumination apparatus as defined in claim 1, further comprising a polarizer for polarizing at least one of the daylight and the photoluminescent light to a polarization being similar to a natural polarization of daylight. ### Claim 8 (depends on 1) The daylight illumination apparatus as defined in claim 1, further comprising a light guide entering probability reducing unit for reducing the probability of the photoluminescent light to enter the light guide. ### Claim 9 (depends on 8) The daylight illumination apparatus as defined in claim 8, wherein, with respect to the optical path, the light guide entering probability reducing unit is arranged between the light guide and the photoluminescent material. ### Claim 10 (depends on 9) The daylight illumination apparatus as defined in claim 9, wherein light guide entering probability reducing unit is a multilayer dielectric reflector being adapted for allowing light coming out of the light guide to transmit through the multilayer dielectric reflector and for reflecting the photoluminescent light emitted by the photoluminescent material. ### Claim 11 (depends on 8) The daylight illumination apparatus as defined in claim 8, wherein the light guide entering probability reducing unit is a light expander for expanding the light guided by the light guide before meeting the photoluminescent material. ### Claim 12 (depends on 8) The daylight illumination apparatus as defined in claim 8, wherein the light guide entering probability reducing unit comprises a transparent plate having two opposing main surfaces and side surfaces connecting the main surfaces, wherein the light guide and the transparent plate are adapted such that light leaving the light guide enters the transparent plate via a side surface of the transparent plate and that the light leaves the transparent plate via a main surface of the transparent plate, wherein the photoluminescent material is arranged on the main surface through which the light leaves the transparent plate. ### Claim 13 (depends on 8) The daylight illumination apparatus as defined in claim 8, wherein the light guide entering probability reducing unit comprises a transparent plate having two opposing main surfaces and side surfaces connecting the main surfaces, wherein the light guide and the transparent plate are adapted such that light leaving the light guide enters the transparent plate via a side surface of the transparent plate and that the light leaves the transparent plate via a main surface of the transparent plate, wherein the photoluminescent material is incorporated into the transparent plate. ### Claim 14 (canceled) ### Claim 15 A daylight illumination method comprising: collecting daylight by a daylight collector, guiding the daylight to an illumination location to be illuminated along an optical path by a light guide, wherein the daylight is absorbed by the light guide, illuminating a photoluminescent material by the daylight for emitting photoluminescent light for illuminating the illumination location when illuminated by the daylight, wherein the photoluminescent material is arranged within the optical path and the photoluminescent light compensates for the absorption of the daylight by the light guide.