Method of making phosphor screens

Abstract

.Iadd. Method comprises applying a portion of initial slurry to a first substrate, spreading the initial slurry on the substrate, removing the excess slurry from the substrate, preparing a reconstituted slurry comprised of the removed excess slurry and a makeup slurry, and then dispensing a portion of reconstituted slurry onto a second substrate. As compared to the initial slurry, the makeup slurry has at least one of (1) a larger proportion of large particles, (2) a larger proportion of phosphor, (3) a greater binder/water ratio and (4) a smaller photosensitizer/binder ratio..Iaddend.

What is claimed is: 
     
       1. The method of making a plurality of phosphor screens comprising the steps of: (a) applying a portion of initial slurry onto a first substrate, said initial slurry including phosphor particles predominantly in the size range of 1 to 20 microns with a minor weight proportion of said particles greater than 10 microns in size, said portion of initial slurry being more than that required to provide a coating of desired thickness on said first substrate,   (b) spreading said portion of initial slurry over said first substrate to said desired thickness,   (c) removing from said first substrate the fraction of said portion of initial slurry which is in excess of that required to provide said coating of said desired thickness,   (d) mixing said removed fraction with makeup slurry to produce a reconstituted slurry, said makeup slurry containing phosphor particles predominantly in the size range of 1 to 20 microns with a larger weight proportion of particles greater than 10 microns in size than the minor weight proportion in said initial slurry,   (e) and then dispensing a portion of said reconstituted slurry onto a second substrate.   
     
     
       2. The method of making a plurality of phosphor screens comprising the steps of: (a) applying a portion of initial slurry onto a first substrate, said initial slurry including phosphor particles predominantly in the size range of 1 to 20 microns with a minor weight proportion of said particles greater than 10 microns in size, binder, photosensitizer, and water, said portion of initial slurry being more than that required to provide a coating of desired thickness on said first substrate,   (b) spreading said portion of initial slurry over said first substrate to said desired thickness,   (c) removing from said first substrate the fraction of said portion of initial slurry which is in excess of that required to provide said coating of said desired thickness,   (d) mixing said removed fraction with makeup slurry to produce a reconstituted slurry, said makeup slurry containing phosphor particles predominantly in the size range of 1 to 20 microns with a larger weight proportion of particles greater than 10 microns in size than the minor weight proportion in said initial slurry, said makeup slurry having a greater phosphor concentration, a greater binder/water ratio, and a smaller photosensitizer/binder ratio than does said initial slurry,   (e) and then dispensing a portion of said reconstituted slurry onto a second substrate.   
     
     
       3. The method of claim 2 wherein said reconstituted slurry is comprised of said removed fraction, makeup slurry and initial slurry. 
     
     
       4. The method of making a plurality of phosphor screens comprising the steps of: (a) applying a portion of initial slurry onto a first substrate, said initial slurry including phosphor particles predominantly in the size range of 1 to 20 microns with a minor weight proportion of said particles greater than 10 microns in size, binder, photosensitizer, and water, said portion of initial slurry being more than that required to provide a coating of desired thickness on said first substrate,   (b) spreading said portion of initial slurry over said first substrate to said desired thickness,   (c) removing from said first substrate the fraction of said portion of initial slurry which is in excess of that required to provide said coating of said desired thickness,   (d) preparing a reconstituted slurry comprised of said removed fraction and a makeup slurry, said makeup slurry containing phosphor particles predominantly in the size range of 1 to 20 microns with at least one of (1) a larger weight proportion of particles greater than 10 microns in size than the minor weight proportion in said initial slurry, (2) a greater phosphor concentration than in said initial slurry, (3) a greater binder/water ratio than in said initial slurry, (4) and a smaller photosensitizer/binder ratio than in said initial slurry,   (e) and then dispensing a portion of said reconstituted slurry onto a second substrate.   
     
     
       5. The method defined in claim 4 wherein said makeup slurry has a larger weight proportion of particles greater than 10 microns in size than the minor weight in said initial slurry. 
     
     
       6. The method defined in claim 4 wherein said makeup slurry has a greater phosphor concentration than in said initial slurry. 
     
     
       7. The method defined in claim 4 wherein said makeup slurry has a greater binder/water ratio than in said initial slurry. 
     
     
       8. The method defined in claim 4 wherein said makeup slurry has a smaller photosensitizer/binder ratio than in said initial slurry. 
     
     
       9. The method of making a plurality of phosphor screens comprising the steps of: (a) applying a portion of initial slurry onto a first substrate, said initial slurry including phosphor particles predominantly in the size range of 1 to 20 microns, said portion of initial slurry being more than that required to provide a coating of desired thickness on said first substrate,   (b) spinning said substrate to spread said portion of initial slurry over said first substrate to said desired thickness and to cause the fraction of said portion of initial slurry which is in excess of that required to provide said coating of said desired thickness to move toward the edges of said first substrate,   (c) removing from said first substrate said excess fraction of initial slurry,   (d) preparing a reconstituted slurry comprised of said removed fraction and a makeup slurry, said makeup slurry containing a greater concentration of phosphor particles predominantly in the size range of 1 to 20 microns than in said initial slurry,   (e) and then dispensing a portion of said reconstituted slurry onto a second substrate.   
     
     
       10. The method of making a plurality of phosphor screens for cathode ray tubes comprising the steps of: (a) applying a portion of initial slurry onto a dry surface of a first faceplate panel for a cathode ray tube, said initial slurry including phosphor particles predominantly in the size range of 1 to 20 microns and containing at least 13.0 weight percent phosphor, said portion of initial slurry being more than that required to provide a coating of desired thickness on said surface of said first substrate,   (b) spinning said substrate to spread said portion of initial slurry over the surface of said first substrate to said desired thickness, and to cause the fraction of said portion of initial slurry which is in excess of that required to provide said coating of said desired thickness to move toward the edges of the surface of said first substrate,   (c) removing said excess fraction of initial slurry from said first substrate,   (d) mixing said removed fraction with makeup slurry and initial slurry to produce a reconstituted slurry, said makeup slurry containing phosphor particles predominantly in the size range of 1 to 20 microns with a greater weight percent of phosphor than in said initial slurry,   (e) and then dispensing a portion of said reconstituted slurry onto a second faceplate panel for a cathode ray tube.