Erect image resin lens array and the manufacture thereof

Abstract

A resin lens plate has, on its planar surface, convex lenslets arranged in a regular pattern with adjacent lenslets being apart from each other by a specified center-to-center pitch. Each of the convex lenslets has a rectangular or hexagonal contour in a plan view of the plate, and the lenslets are arranged such that the direction in which the center-to-center distance between adjacent lenslets takes a maximum value is in parallel with the lengthwise side of the plate. A groove or a ridge is formed along the bisector of a center-to-center line drawn between each pair of adjacent lenslets, and a light absorbing film is formed over the groove or the ridge. The groove or ridge inhibits the entry of stray light to the lenslet from adjacent lenslets.

What is claimed:  
     
         1 . A method for manufacturing a die used for fabricating by injection molding a lens plate carrying convex lenslets each having a spherical or aspherical end surface arranged in a regular pattern on its surface comprising the steps of: 
 obtaining a mother matrix by arranging spherically convex resin lenslets in a regular pattern on a planar substrate, and processing, for each spherically convex lenslet of the mother matrix, the periphery of a circle which has the center essentially corresponding with the center of the lenslet;    forming a conductive film over the resin of the mother matrix thus processed;    plating a metal to form a metal plating having a specified thickness on the conductive film; and    obtaining a die by parting the metal plating from the mother matrix.    
     
     
         2 . A method for manufacturing a die as described in  claim 1  wherein each convex lenslet has a quadrangular or hexagonal contour in a plan view of the plate, and the lenslets are arranged such that the direction in which the center-to-center distance between adjacent lenslets takes a maximum value is in parallel with the lengthwise side of the plate.  
     
     
         3 . A method for manufacturing a die used for fabricating by injection molding a lens plate carrying convex lenslets each having a spherical or aspherical end surface arranged in a regular pattern in its surface comprising the steps of: 
 obtaining a mother matrix by arranging spherically convex resin lenslets in a regular pattern on a planar substrate, and forming a groove or a ridge along the bisector of a center-to-center line drawn between each pair of adjacent spherically convex lenslets;    forming a conductive film over the resin of the mother matrix which had grooves or ridges formed on its surface;    plating a metal to form a metal plating having a specified thickness on the conductive film; and    obtaining a die by parting the metal plating from the mother matrix.    
     
     
         4 . A method for manufacturing a die as described in  claim 3  wherein each convex lenslet has a quadrangular or hexagonal contour in a plan view of the plate, and the lenslets are arranged such that the direction in which the center-to-center distance between adjacent lenslets takes a maximum value is in parallel with the lengthwise side of the plate.  
     
     
         5 . A method for manufacturing a die as described in  claim 2  or  3  wherein the convex lenslets are densely packed.  
     
     
         6 . A method for manufacturing a die as described in  claim 2  or  3  wherein the processing is achieved by using a laser beam.  
     
     
         7 . A method for fabricating a resin lens plate comprising the steps of: preparing a die manufactured by the method as described in  claim 2  and an unprocessed die, combining the dies such that the concavities thereon face each other, and mounting the dies to respective die-sets; 
 introducing a gap having a specified width between the two apposed dies, and injecting a resin through the gap;  
 parting the two dies and removing a resin lens plate; and  
 forming, for each convex lenslet formed on the resin lens plate, a light absorbing film over the processed parts outside the periphery of a circle which has the center essentially corresponding with the center of the lenslet.  
 
     
     
         8 . A method for fabricating a resin lens plate comprising the steps of: 
 preparing a die manufactured by the method as described in  claim 2  and a flat die having no concavities on its surface, combining the dies such that the concavity carrying surface of the former faces the flat surface of the latter, and mounting the dies to respective die-sets;    introducing a gap having a specified width between the two apposed dies, and injecting a resin through the gap;    parting the two dies and removing a resin lens plate; and    forming, for each convex lenslet formed on the resin lens plate, a light absorbing film over the processed parts outside the periphery of a circle which has the center essentially corresponding with the center of the lenslet.    
     
     
         9 . A method for fabricating a resin lens plate comprising the steps of: 
 preparing a die manufactured by the method as described in  claim 4  and an unprocessed die, combining the dies such that the concavities thereon face each other, and mounting the dies to respective die-sets;    introducing a gap having specified width between the two apposed dies, and injecting a resin through the gap;    parting the two dies and removing a resin lens plate; and    forming a light absorbing film over a groove or a ridge formed between teach pair of adjacent convex lenslets on the resin lens plate.    
     
     
         10 . A method for fabricating a resin lens plate comprising the steps of: 
 preparing a die manufactured by the method as described in  claim 4  and a flat die having no concavities on its surface, combining the dies such that the concavity carrying on its surface of the former faces the flat surface of the latter, and mounting the dies to respective die-sets;    introducing a gap having a specified width between the two opposed dies, and injecting a resin through the gap;    parting the two dies and removing a resin lens plate; and    forming a light absorbing film over a groove or a ridge formed between each pair of adjacent convex lenslets on the resin lens plates.    
     
     
         11 . A method for fabricating a resin lens plate comprising the steps of: 
 preparing two dies manufactured by the method as described in  claim 4 , combining the dies such that the concavity carrying surfaces of the dies face each other, and mounting the dies to respective die-sets;    introducing a gap having a specified width between the two apposed dies, and injecting a resin through the gap;    parting the two dies and removing a resin lens plate; and    forming a light absorbing film over a groove or a ridge formed between each pair of adjacent convex lenslets on the resin lens plate.    
     
     
         12 . A method for fabricating an erect image resin lens array comprising stacking two or more resin lens plates containing at least one resin lens plate prepared by a method as described in any one of the  claims 7  to  11 .