Method and apparatus to enhance spectral purity of a light source

Abstract

A reflective filter serving as a multi-bandpass filter for a light source configured to emit light in a plurality of color primary wavelengths to improve color purity. The addition of a reflective/recirculation assembly reinforces and recirculates light not passed by the multi-bandpass filter back into a desired spectrum, which is subsequently passed by the multi-bandpass filter, or converts light not passed by the multi-bandpass into electrical energy for use by the system. The reflective filter, solely or along with the recirculation assembly, can be placed adjacent a conventional light source. Alternatively the multi-bandpass filter and the recirculation assembly can be placed in a modified light source, or placed in an optical stack along the path of light emission. Collimating structures that enforce the light into desired incident angle of attack onto the reflective filter can be included to enhance the efficiency of the reflective elements in the assembly.

1 - 65 . (canceled) 
     
     
         66 : An assembly for adjusting the spectral emissions of transmitted light of a liquid crystal display, comprising:
 a light source having an emission output surface operable to output light into a backlight assembly;   a light guide adapted to receive incident light from the light source at a first surface, and to emit light at a second surface;   a color filter surface containing a plurality of pixel color-filtering elements disposed between a plurality of light-transmitting pixel elements of the liquid crystal layer and an illumination surface of a display;   a collimating layer interposed between the light source and a first reflective filter and adapted to collimate output light prior to incidence on the first reflective filter; and   a first reflective filter interposed between the collimating surface and the illumination surface of the display, wherein the first reflective filter is operable to pass at least one wave-band of wavelengths of light source transmitted light, and to reflect wavelengths not of the multi-band,   wherein a surface of photo-emissive color-conversion pixel elements is operable to absorb a wavelength of light source light, and configured to emit in at least one waveband of the multi-band substantially transmitted by the pixel color filter elements.   
     
     
         67 : The assembly of  claim 66  wherein the first reflective filter is disposed adjacent to the light source output surface and between the light source and the light guide. 
     
     
         68 : The assembly of  claim 66  wherein the first reflective filter is disposed within an optical stack between the light guide and the color conversion surface of the display. 
     
     
         69 : The assembly of  claim 66  further including a collimating structure interposed between the light source and the first reflective filter and adapted to collimate output light prior to incidence on the reflective filter. 
     
     
         70 : The assembly of  claim 66 , additionally comprising a second reflective filter disposed between the plurality of conversion pixel elements and the illumination surface, and operable to permit transmission of converted light of a multi-band, and to reflect light not of the multi-band. 
     
     
         71 : The assembly of  claim 66  wherein the multi-band of transmitted wavelengths corresponds with wavelengths of pixel primary colors in the visible spectrum. 
     
     
         72 : The assembly of  claim 70  wherein the color-conversion pixel elements comprise at least one light recycling particle operable to absorb light reflected by a reflective filter and to convert at least a portion of the excitation wavelength light into at least of a set comprising: the waveband of a pixel color component, the excitation waveband of a light emitting color conversion particle, the excitation waveband of a light recycling particle, and electrical energy. 
     
     
         73 : The assembly of  claim 66 , wherein the reflective filter comprises a dichroic filter. 
     
     
         74 : A display system, comprising:
 a display module comprising an outer illumination surface and containing an array of light-emitting pixels comprising separate primary-color waveband elements of a first multi-band;
 a plurality of light sources operable to emit light towards the pixelated illumination surface of the display panel; 
 a first reflective filter layer disposed adjacent the plurality of light sources and operable to reflect light source light over a second multi-band of wavelengths, and to transmit wavelengths not of the second multi-band; 
 a color conversion layer comprising a composition of color converting particles disposed to receive transmitted light source light and reflected light and operable to absorb in at least one of the received wavelength bands, and to emit at the at least one selected wavelength bands of the first multi-band; 
 a color filter surface containing a plurality of pixel color-filtering elements of distinct primary color wavebands disposed in a light path between the color conversion layer and the illumination surface of the display panel; and 
 wherein the first reflective filter, the color conversion layer, and the color filter elements form an arrangement disposed between the light emission source and the illumination surface of the display panel. 
   
     
     
         75 : The system of  claim 74 , wherein the color converting layer includes a recycling element comprising a first particle adapted to absorb light source wavelengths, and to emit recycled light at a wavelength not of the multi-band wavelengths, and a second particle adapted to absorb recycled light and to emit light at a wavelength of the multi-band. 
     
     
         76 : The system of  claim 75 , wherein the recycled light is of a shorter wavelength than the light source wavelengths. 
     
     
         77 : The system of  claim 75 , wherein the recycled light is of a longer wavelength than the light source wavelengths. 
     
     
         78 : The system of  claim 75  wherein the light source wavelengths are visible wavelengths and the first particle is adapted to emit light at invisible wavelengths, and wherein the second particle is adapted to absorb light of less-visible wavelengths. 
     
     
         79 : The system of  claim 75 , wherein the first particle and the second particle are disposed in adjacent deposition layers, and wherein the first reflective filter is substantially parallel to the adjacent deposition layers. 
     
     
         80 : The system of  claim 74 , further comprising a collimating layer interposed between the light source array and the first reflective filter, and wherein the collimating layer is adapted to collimate output light prior to incidence on the first reflective filter. 
     
     
         81 : The system of  claim 74 , wherein a second reflective filter layer operable to receive the light source light and color conversion layer light, and to transmit at least one selected wavelength of the first multi-band, and to reflect light not of the first multi-band. 
     
     
         82 : The system of  claim 74 , wherein a polarizing layer comprising a plurality of polarizing elements disposed between the reflective filter and the color conversion elements, and operable to transmit light of a selected polarization, and not transmit a light not of the selected polarization. 
     
     
         83 : The system of  claim 74 , wherein the multi-band comprises wavelengths in the visible spectrum aligned with the multi-band of the color filter primary-color wavebands. 
     
     
         84 : The system of  claim 83 , wherein the first reflective filter is operable to reflect less-visible wavelengths. 
     
     
         85 : The system of  claim 74  further comprising a layer containing light recycling particles disposed between the first and the second reflective filters, wherein the light source recycling layer is operable to convert reflected wavelengths into wavelengths substantially in the excitation range of the color conversion particle layer. 
     
     
         86 : The system of  claim 74 , wherein the color-filter surface comprises an array of reflective filter elements, wherein the reflective filters are configured to transmit light in the first multi-band, and reflect light not of the first multi-band. 
     
     
         87 : An OLED display assembly comprising:
 a plurality of OLED light emitting sources configured in an array of pixels emitting light towards the illumination surface of a display panel;   a reflective layer disposed behind the light emitting sources and configured to redirect light substantially towards the illumination surface;   a reflective filter disposed in a light path of the light sources and operable to reflect light of a first multi-band of wavelengths, and to transmit wavelengths not of the first multi-band;   an array of pixel color conversion elements comprising at least one particle disposed to receive light from the pixel emitter light sources, and operable to absorb light at a first wavelength band and to emit light in at least one second wavelength band of the first multi-band; and   a polarizing element disposed to receive emitted light of the color conversion element and transmit light of a selected polarization, and not transmit light not of the selected polarization.   
     
     
         88 : The system of  claim 87 , wherein the reflective layer is in a bottom electrode of the OLED emitter and is further configured to alter the polarization of reflected light. 
     
     
         89 : The assembly of  claim 87  wherein the color conversion element comprises an additional recycling conversion particle adapted to absorb reflected light from the reflective filters, and to emit light at a third wavelength, and an additional conversion particle adapted to absorb light of the third wavelength, and to emit light in at least one wavelength of the first multi-band of wavelengths. 
     
     
         90 : The assembly of  claim 87 , further comprising a photovoltaic conversion element including a particle operable to absorb light at a conversion wavelength band and to convert at least a portion of the conversion wavelength light into electrical energy. 
     
     
         91 : The assembly of  claim 87  wherein the color filter integrates the reflective filter.