Cover glass

Abstract

A cover glass includes: a glass substrate having a convex and concave shape formed on at least one of surfaces thereof by an antiglare treatment; and an antireflection film disposed on the surface of the glass substrate, the surface having the convex and concave shape. In the cover glass, a difference Δa* in a* value between any two points within a surface of the cover glass on the side where the antireflection film is present and a difference Δb* in b* value between any two points within the surface of the cover glass on the side where the antireflection film is present satisfy the following expression: √{(Δa*) 2 +(Δb*) 2 }≦4.

1 . A cover glass comprising: a glass substrate having a convex and concave shape formed on at least one of surfaces thereof by an antiglare treatment; and an antireflection film disposed on the surface of the glass substrate, the surface having the convex and concave shape, wherein
 a difference Δa* in a* value between any two points within a surface of the cover glass on the side where the antireflection film is present and a difference Δb* in b* value between any two points within the surface of the cover glass on the side where the antireflection film is present satisfy the following expression (1).
   √{(Δ a *) 2 +(Δ b *) 2 }≦4  (1)
 
   
     
     
         2 . The cover glass according to  claim 1 , wherein the Δa* and the Δb* are determined by selecting any square portion of 10 cm 2  as a measuring range from the glass substrate, dividing the measuring range into 11×11 equal portions, examining all 100 intersections of equally dividing lines for a* values and b* values, determining a maximum value a* max  of the a* values, a minimum value a* min  of the a* values, a maximum value b* max  of the b* values, and a minimum value b* min  of the b* values, from the a* values and b* values, and taking a difference (a* max −a* min ) between the a* max  and the a* min  as the Δa* and a difference (b* max −b* min ) between the b* max  and the b* min  as the Δb*. 
     
     
         3 . The cover glass according to  claim 1 , wherein the glass substrate has a microcrack(s) having a maximum depth of less than 3 μm on the surface thereof, the surface having the convex and concave shape. 
     
     
         4 . The cover glass according to  claim 1 , wherein the surface of the cover glass, which has the convex and concave shape, has a degree of ion exchange of 1% or more and 25% or less. 
     
     
         5 . The cover glass according to  claim 4 , wherein the degree of ion exchange is a degree of ion exchange determined using aluminum as an index. 
     
     
         6 . The cover glass according to  claim 1 , which has a haze of 1% to 35%. 
     
     
         7 . The cover glass according to  claim 1 , wherein the antireflection film is a laminate comprising one or more layers containing niobium and one or more layers containing silicon. 
     
     
         8 . The cover glass according to  claim 1 , which has a luminous reflectance of 2% or less. 
     
     
         9 . The cover glass according to  claim 1 , further comprising an antifouling film disposed on the antireflection film, wherein a contact angle of water on a surface of the cover glass on the side where the antifouling film is present is 90° or larger.