Patent ID: 11953712
Assignee: JAPAN DISPLAY INC.
Field: Electrical machinery, apparatus, energy (Electrical engineering)
Classification: CPC G | IPC F

Claim 13:
14. The illumination device of claim 12, wherein
a length of the first grooves along a first direction is formed according to the following equation (1), L
      ⁢
      11
     
     =
     
      
       
        tan
         
        26.5
        °
       
       
        tan
        ⁢
        δ
       
      
      ⁢
      
       L
       0
      
      ⁢
      d
     
    
   
   
    
     (
     1
     ), L11: length of the first grooves along the first direction,, δ: angle of incidence of light on the first light guide,, 26.5°: angle of incidence at which light is made incident on the first light guide at a small loss, and, d: thickness of the first light guide, and
a contact angle of the protruding portion is formed according to the following equation (2), θ
     =
     
      
       arc
       ⁢
       sin
       ⁢
       
        (
        
         sin
         ⁢
         2
         ⁢
         
          θ
          0
         
         ⁢
         
          
           tan
            
           26.5
           °
          
          
           tan
           ⁢
           δ
          
         
        
        )
       
      
      2
     
    
   
   
    
     (
     2
     ), θ: contact angle of the protruding portion, and, Lo≥2 mm and θo≥2°.