optical arrangement and an autostereoscopic display device incorporating the same

Abstract

An autostereoscopic display lens arrangement comprises an array ( 9 ) of parallel lenticular lenses ( 11 ), wherein the lens array comprises first and second materials of different refractive indices ( 60,62 ) sandwiched between planar substrates, with the interface between the first and second materials defining the lens surfaces. The first material has a refractive index n 1 , the lens array has a lens pitch p and the lenticular lenses have a radius of curvature at their centre of R, and the lenses satisfy n 1 (p/2R)>0.6. This arrangement gives reduced banding and loss of intensity at steep angles when used in an autostereoscopic display.

1 . An optical arrangement having at least a lens mode in which it is a lens arrangement comprising an array ( 9 ) of positive lenticular lenses ( 11 ), each respective one of the positive lenses comprising a first layer and second layer having an interface between each other defining the lenticular lens surface, the first layer having a first refractive index and the second layer having a second refractive index that is different from the first refractive index, the lens array having a lens pitch and the lenticular lens surfaces having a radius of curvature at their centre, wherein the product of the first refractive index with the lens pitch divided by two times the radius of curvature is greater than 0.6. 
     
     
         2 . An optical arrangement as claimed in  claim 1 , wherein the product is greater than 0.8. 
     
     
         3 . An optical arrangement as claimed in  claim 1 , wherein the product is greater than 1. 
     
     
         4 . An optical arrangement as claimed in  claim 1 , wherein the lens arrangement has a viewer side opposite to a display side and the first layer is on the viewer side of the lens arrangement. 
     
     
         5 . A lens arrangement as claimed in  claim 1 , wherein the first refractive index is the lowest refractive index of the first and second refractive indices. 
     
     
         6 . A lens arrangement as claimed in  claim 1  wherein the absolute value of the refractive index difference between the first and second refractive indices is in between 0.05 and 0.22. 
     
     
         7 . A lens arrangement as claimed in  claim 6 , wherein the absolute value is between 0.05 and 0.15. 
     
     
         8 . A lens arrangement as claimed in  claim 1  wherein the highest refractive index of the first and second refractive indices is in the range 1.4 to 1.65. 
     
     
         9 . A lens arrangement as claimed in  claim 1 , wherein the lowest refractive index of the first and second refractive indices is in the range 1.3 to 1.5. 
     
     
         10 . A lens arrangement as claimed in  claim 1  wherein the first layer and the second layer are optically isotropic. 
     
     
         11 . A lens arrangement as claimed in  claim 1 , wherein the first and second layers have substantially the same Abbe number. 
     
     
         12 . A lens arrangement as claimed in  claim 1  having an area wherein the interface between the first layer and the second layer is substantially flat. 
     
     
         13 . An autostereoscopic display device comprising:
 an image providing means ( 3 ) and an optical arrangement ( 9 ) according to  claim 1  positioned in front of the image providing means.   
     
     
         14 . An autostereoscopic display device according to  claim 13 , wherein the image forming means is an electronic display panel ( 3 ) 
     
     
         15 . An autostereoscopic display device according to  claim 13 , wherein the optical arrangement is positioned such that when in the lens mode, the first layer is on the viewer side of the optical arrangement. 
     
     
         16 . An autostereoscopic device according to  claim 13  wherein the lens arrangement is positioned such that the second layer is closer to the image providing means than the first layer and wherein the second refractive index is the lowest refractive index of the first and the second refractive indices. 
     
     
         17 . A method of displaying an autostereoscopic image, comprising providing an image comprising multiple views and projecting the image through a lens arrangement according to  claim 1 .