CRT panel glass and production method thereof and CRT

Abstract

A panel glass wherein a surface treating film is formed on a substrate glass so that overall transmittance distribution within an effective picture plane satisfies a specific mathematical expression, whereby, even with a flattened panel glass, a uniform-brightness image can be observed with a good contrast, and occurrence of a double image is suppressed; and a CRT.

1 . A CRT panel glass having a surface treating film formed on an outer surface of a substrate glass, characterized in that the surface treating film is formed on the outer surface so that the value A defined by the following mathematical expression (1) is less than 1 within an effective picture plane:  
       
         
           
             
               
                 
                   
                     
                       Value 
                        
                       
                           
                       
                        
                       A 
                     
                     = 
                     
                       
                          
                         
                           
                             1 
                             - 
                             
                               
                                 Tgf 
                                  
                                 
                                   ( 
                                   min 
                                   ) 
                                 
                               
                               
                                 Tgf 
                                  
                                 
                                   ( 
                                   max 
                                   ) 
                                 
                               
                             
                           
                           
                             1 
                             - 
                             
                               
                                 Tg 
                                  
                                 
                                   ( 
                                   min 
                                   ) 
                                 
                               
                               
                                 Tg 
                                  
                                 
                                   ( 
                                   max 
                                   ) 
                                 
                               
                             
                           
                         
                          
                       
                       . 
                     
                   
                 
                 
                   
                     Mathematical 
                      
                     
                         
                     
                      
                     expression 
                      
                     
                         
                     
                      
                     
                       ( 
                       1 
                       ) 
                     
                   
                 
               
             
           
           
           
               
           
         
         In the mathematical expression (1):  
         Tg(min) and Tg(max) represent the minimum transmittance (%) and the maximum transmittance (%) of the substrate glass itself, respectively; and  
         Tgf(max) and Tgf(min) represent the maximum transmittance (%) and the minimum transmittance (%) of an integral body comprising the substrate glass and the surface treating film.  
       
     
     
         2 . The CRT panel glass according to  claim 1 , characterized in that the difference between the minimum transmittance Tf(min) of the surface treating film and the maximum transmittance Tf(max) of the surface treating film is within a range of from 2 to 20%.  
     
     
         3 . The CRT panel glass according to  claim 1  or  2 , characterized in that Tgf(min)/Tgf(max) is at least 0.8.  
     
     
         4 . The CRT panel glass according to any one of  claims 1  to  3 , characterized in that the surface treating film is an antireflection film against outer light.  
     
     
         5 . The CRT panel glass according to any one of  claims 1  to  4 , characterized in that Tg(max) is within a range of from 30 to 70%.  
     
     
         6 . The CRT panel glass according to any one of  claims 1  to  5 , characterized in that the reflectance as observed from inside of the substrate glass is at most 15%.  
     
     
         7 . The CRT panel glass according to any one of  claims 1  to  6 , characterized in that the surface treating film is a film having a construction such that a light absorbing layer containing titanium nitride as the main component and a layer containing silica as the main component are formed in this order on the substrate glass.  
     
     
         8 . The CRT panel glass according to  claim 7 , characterized in that the light absorbing layer containing titanium nitride as the main component, has a film thickness distribution.  
     
     
         9 . The CRT panel glass according to  claim 8 , characterized in that the layer containing silica as the main component, has a film thickness distribution reverse to the light absorbing layer containing titanium nitride as the main component.  
     
     
         10 . The CRT panel glass according to any one of  claims 1  to  9 , characterized in that Tgf(max) is within a range of from 30 to 70%.  
     
     
         11 . The CRT panel glass according to any one of  claims 1  to  10 , characterized in that the transmittance Tf at an optional position of the surface treating film is within a range of from 40 to 90%.  
     
     
         12 . The CRT panel glass according to any one of  claims 1  to  11 , characterized in that the outer diameter of the CRT panel glass is at least 5 times the value R calculated by the following mathematical expression (2):  
       Value R (unit: mm)=Screen diagonal length (inch)×42.5+45.0   Mathematical expression (2) 
     
     
         13 . A method for producing a CRT panel glass characterized in that a surface treating film is formed on an outer surface of a substrate glass, characterized in that the surface treating film is formed on the outer surface so that the value A defined by the mathematical expression (1) is less than 1 within an effective picture plane.  
     
     
         14 . A CRT having the CRT panel glass as defined in any one of  claims 1  to  12 .