Light-emitting device and photo-therapy device comprising a light-emitting device

Abstract

A light-emitting device (100) is disclosed. The light-emitting device (100) comprises a plurality of light-emitting elements (135) or light sources and a power module (120) adapted to selectively convey, supply or provide electrical power to the light-emitting elements (135). The power module (120) may be dimensioned such as to be able to power only a proper subset of the light-emitting elements (135) of the light-emitting device (100) at a given time, the subset having a maximum number of light-emitting elements (135) included therein with respect to the number of light-emitting elements (135) included in the all subsets of the light-emitting elements (135) of the light-emitting device (100). The plurality of sets of light-emitting elements (135) may be arranged so as to emit light over a light emission area, and the plurality of sets of light-emitting elements (135) may be arranged relatively to each other such that different sets of light-emitting elements (135) emit light over different portions of the light emission area.

1 . A light-emitting device comprising:
 a light-emitting module comprising a plurality of sets of light-emitting elements; and   a power module adapted to selectively convey electrical power to the plurality of sets during respective non-overlapping time intervals for powering the respective sets;   wherein the plurality of sets of light-emitting elements are arranged so as to emit light over a light emission area and the plurality of sets of light-emitting elements are arranged relatively to each other such that different sets of light-emitting elements emit light over different portions of the light emission area.   
     
     
         2 . The light-emitting device according to  claim 1 , wherein the duration of at least one of the time intervals is selected based on:
 an estimation of heat generating capacity of the light-emitting device in a skin portion of a subject as a function of time caused by the light-emitting device emitting light on the skin portion; and   a maximum allowable blood temperature in the skin of the subject.   
     
     
         4 . The light-emitting device according to  claim 1 , further comprising a control module adapted to control operation of the power module so as to cause the power module to convey power to the plurality of sets during respective non-overlapping time intervals such that there is an idle time period having a selected duration between conveyances of power to subsequently powered sets of the plurality of sets. 
     
     
         5 . A light-emitting device according to  claim 4 , wherein the duration of at least one of the time intervals is selected based on:
 an estimation of heat generating capacity of the light-emitting device in a skin portion of a subject as a function of time caused by the light-emitting device emitting light on the skin portion; and   a maximum allowable blood temperature in the skin of the subject; and   wherein the duration of the idle time period is selected based on:
 an estimation of the heat transporting capacity of the blood flow in the skin of the subject; 
 a measurement of blood temperature in the skin of the subject; and/or 
 a measurement of skin blood perfusion in the subject. 
   
     
     
         6 . A light-emitting device according to  claim 1 , further comprising a control module adapted to control operation of the power module so as to cause the power module to convey power to the plurality of sets such that there is a spatial separation between subsequently powered sets of the plurality of sets on basis of the arrangement of the plurality of sets relatively to each other in the light-emitting device. 
     
     
         7 . A light-emitting device according to  claim 1 , wherein the power module is adapted to convey electrical power simultaneously to each set of at least some of the plurality of sets during an initial illumination time period for powering each of the at least some of the plurality of sets prior to selectively conveying electrical power to the plurality of sets during respective non-overlapping time intervals for powering the respective sets. 
     
     
         8 . A light-emitting device according to  claim 1 , wherein the plurality of sets of light-emitting elements are arranged relatively to each other such that each of the portions of the light emission area comprises subportions that are spatially separated with respect to each other. 
     
     
         9 . A light-emitting device according to  claim 1 , wherein the plurality of sets of light-emitting elements are arranged such that the light-emitting device is adapted to generate heat in skin of a portion of a subject caused by the light-emitting device emitting light over the light emission area onto the skin portion, and wherein the light-emitting elements of each set of the plurality of sets of light-emitting elements are arranged so as to extend along a direction perpendicular to a main blood flow direction in the portion of the subject when the light-emitting device emits light over the light emission area onto the skin.