Phosphor wheel with inorganic binder

Abstract

A light conversion device is disclosed. The light conversion device includes a substrate and a wavelength conversion element ( 111 ). The wavelength conversion element ( 111 ) includes an inorganic binder, such as sodium silicate. Also disclosed are phosphor wheels and light engines including such phosphor wheels. Further disclosed are high-power laser projection display systems comprising a laser having a power of from about 60 W and about 300 W and a light conversion device. The use of an inorganic binder permits high thermal stability at reasonable cost.

1 - 20 . (canceled) 
     
     
         21 . A light conversion device, comprising:
 a wavelength conversion element configured to absorb light of an excitation wavelength and generate light of an emission wavelength, the wavelength conversion element comprising an inorganic binder and a phosphor, wherein the inorganic binder comprises an inorganic material, a filler and a dispersant, wherein the filler has a thermal expansion coefficient that is substantially equivalent to a thermal expansion coefficient of the inorganic material, and wherein the filler has a density that is substantially equivalent to a density of the inorganic material.   
     
     
         22 . The light conversion device of  claim 21 , wherein a weight ratio of the phosphor to the inorganic binder is from about 1:1 to about 5:1. 
     
     
         23 . The light conversion device of  claim 21 , wherein the inorganic material is selected from the group consisting of silicates, aluminates, phosphates, borates, and inorganic sol-gels; wherein the filler is selected from the group consisting of a silica, a silicate, an aluminate, a phosphate, diamond powder, a metal powder, a nitride, an oxide, and a metal sulfide; and wherein the dispersant is an organic dispersant selected from the group consisting of polyvinylpyrrolidone, polyacrylate, gelatin, polyvinyl alcohol, cellulose, styrene-co-maleic anhydride, and lignosulfate; or the dispersant is an inorganic dispersant selected from the group consisting of hexametaphosphate, silicate, polyphosphate, and fumed silica. 
     
     
         24 . The light conversion device of  claim 23 , wherein the inorganic material is made from a first component and a second component, wherein:
 the first component has a viscosity of 1 to 50 mPa·sec, a density of 0.8 to 1.3 g/cm3, and a solids content of more than 10%; and   the second component has a viscosity of 0 to 50 mPa·sec, a density of 0.6 to 1.0 g/cm3, and a solids content of more than 10%.   
     
     
         25 . The light conversion device of  claim 24 , wherein the first component is a semitransparent liquid and the second component is a transparent liquid. 
     
     
         26 . The light conversion device of  claim 24 , wherein a ratio of the first component to the second component is from about 1:1 to about 7:3. 
     
     
         27 . The light conversion device of  claim 24 , wherein the inorganic material is prepared by stirring a mixture of the first and second components for a period of from about 2 hours to about 3 hours at a temperature of about 25° C. to about 30° C. 
     
     
         28 . The light conversion device of  claim 21 , wherein the inorganic binder has at least one of a thermal expansion coefficient of about 0.5 to about 25 ppm/°C or a curing temperature of from about 100° C. to about 500° C. 
     
     
         29 . The light conversion device of  claim 21 , wherein the inorganic binder is capable of withstanding working temperatures greater than 200° C., and wherein the inorganic binder has a light transmittance of at least 80%. 
     
     
         30 . The light conversion device of  claim 21 , further comprising:
 a substrate upon which the wavelength conversion element is mounted, wherein the substrate is in the shape of a disk; and   a motor, the motor arranged to rotate the substrate around an axis normal to the substrate.   
     
     
         31 . A method for making a light conversion device, comprising:
 applying a wavelength conversion element comprising an inorganic binder and a phosphor to a substrate, wherein the inorganic binder comprises an inorganic material, a filler, and a dispersant, wherein the filler has a thermal expansion coefficient that is substantially equivalent to a thermal expansion coefficient of the inorganic material, and wherein the filler has a density that is substantially equivalent to a density of the inorganic material.   
     
     
         32 . The method of  claim 31 , wherein the wavelength conversion element is applied to the substrate by dispensing, spraying, brushing, or silk printing. 
     
     
         33 . The method of  claim 31 , wherein the inorganic binder has a thermal expansion coefficient of about 0.5 to about 25 ppm/°C. 
     
     
         34 . The method of  claim 31 , further comprising curing the inorganic binder at a temperature of from about 100° C. to about 500° C. 
     
     
         35 . The method of  claim 31 , wherein the inorganic material is selected from the group consisting of silicates, aluminates, phosphates, borates, and inorganic sol-gels; wherein the filler is selected from the group consisting of a silica, a silicate, an aluminate, a phosphate, diamond powder, a metal powder, a nitride, an oxide, and a metal sulfide; and wherein the dispersant is an organic dispersant selected from the group consisting of polyvinylpyrrolidone, polyacrylate, gelatin, polyvinyl alcohol, cellulose, styrene-co-maleic anhydride, and lignosulfate; or the dispersant is an inorganic dispersant selected from the group consisting of hexametaphosphate, silicate, polyphosphate, and fumed silica. 
     
     
         36 . The method of  claim 35 , wherein the inorganic material is made from a first component and a second component, wherein:
 the first component has a viscosity of 1 to 50 mPa·sec, a density of 0.8 to 1.3 g/cm3, and a solids content of more than 10%; and   the second component has a viscosity of 0 to 50 mPa·sec, a density of 0.6 to 1.0 g/cm3, and a solids content of more than 10%.   
     
     
         37 . The method of  claim 36 , wherein the inorganic material is prepared by stirring a mixture of the first and second components for a period of about 2 hours to about 3 hours at a temperature of about 25° C. to about 30° C. 
     
     
         38 . The method of  claim 36 , further comprising curing the inorganic binder made from the first and second components in a step-by-step process comprising:
 performing a first curing at a temperature of about 60° C. to about 90° C. for a period of about 0.2 hours to about 1 hour; and   subsequently performing a second curing at a temperature of about 150° C. to about 200° C. for a period of about 0.4 hours to about 2 hours.   
     
     
         39 . The method of  claim 36 , wherein the first component is a semitransparent liquid and the second component is a transparent liquid, and/or wherein a ratio of the first component to the second component is from about 1:1 to about 7:3. 
     
     
         40 . A laser projection display system, comprising:
 a laser light having a power of from about 60 W to about 300 W; and   a light conversion device that is a phosphor wheel comprising:
 a substrate; and 
 a wavelength conversion element configured to absorb light of an excitation wavelength and generate light of an emission wavelength, the wavelength conversion element comprising an inorganic binder and a phosphor, wherein the inorganic binder comprises an inorganic material, a filler and a dispersant, wherein the filler has a thermal expansion coefficient that is substantially equivalent to a thermal expansion coefficient of the inorganic material, wherein the thermal expansion coefficient of the inorganic binder is about 0.5 to about 25 ppm/°C, and wherein the filler has a density that is substantially equivalent to a density of the inorganic material.