Patent Publication Number: US-2010109172-A1

Title: Mold for making lens array and method for making lenses

Description:
BACKGROUND 
     1. Technical Field 
     The present invention relates to molds, and particularly, to a mold for molding a lens array and a method for making a plurality of lenses using the mold. 
     2. Description of Related Art 
     Currently, camera modules are widely applied in a variety of portable electronic devices, such as mobile phones. A camera module contains one or more lenses. Most portable electronic devices are becoming progressively miniaturized over time. Thus camera modules, and the lenses thereof, are correspondingly becoming smaller and smaller. Such lenses are typically also lightweight. 
     Injection molding has been a common method used for making lenses. Typically, chambers for molding lenses are radially arranged in a mold. All of the chambers are connected by runners to a sprue, which is in a center of the mold. With this arrangement, the number of chambers is limited, and thus the number of the lenses that can be made in a single molding cycle is also limited. 
     What is needed, therefore, is a mold and a method for making lenses using the mold, which can overcome the above-described shortcomings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Many aspects of the present mold and method can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present mold and method. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views. 
         FIG. 1  is a cross-sectional view of part of a mold in accordance with an exemplary embodiment, the mold including a first mold core and a second mold core, the first mold core and the second mold core being in a position ready for molding.  FIG. 2  is a bottom plan view of the first mold core of  FIG. 1 . 
         FIG. 3  is a cross-sectional view of the first mold core shown in  FIG. 2 , taken along a line III-III thereof. 
         FIG. 4  is a top plan view of the second mold core of  FIG. 1 . 
         FIG. 5  is a cross-sectional view of the second mold core shown in  FIG. 4 , taken along a line V-V thereof. 
         FIG. 6  is similar to  FIG. 1 , but showing a lens array made in the mold. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Embodiments of the present mold and method will now be described in detail below and with reference to the drawings. 
     Referring to  FIGS. 1 and 6 , an exemplary mold  100  for molding a lens array  150  is shown. The mold  100  includes a first mold core  110  and a second mold core  120 . The first mold core  110  and the second mold core  120  are shown in a position ready for molding, and cooperatively define a chamber  130  therebetween in such position. The first mold core  110  has a first molding surface  115  facing toward the second mold core  120 . The second mold core  120  has a second molding surface  125  facing toward the first mold core  110 . The chamber  130  is defined between the first molding surface  115  and the second molding surface  125 . 
     Referring also to  FIGS. 2 to 5 , an area of each of the first molding surface  115  and the second molding surface  125  closely relates to the number of lenses  200  in the lens array  150  (see  FIG. 6 ). The first molding surface  115  and the second molding surface  125  are each generally rectangular-shaped. The first molding surface  115  is comprised of an array of spaced first molding portions  112 , and a plurality of second molding portions  111  interconnecting all the first molding portions  112 . In the illustrated embodiment, the array is in the form of a regular matrix of rows and columns. The second molding portions  111  are interconnected, thereby cooperatively constituting a single, continuous surface. The second molding surface  125  is comprised of an array of spaced third molding portions  122 , and a plurality of fourth molding portions  121  interconnecting all of the third molding portions  122 . In the illustrated embodiment, the array is in the form of a regular matrix of rows and columns, corresponding to the array of first molding portions  112 . The fourth molding portions  121  are interconnected, thereby cooperatively constituting a single, continuous surface. The first and third molding portions  112 ,  122  are each concave surfaces. In other embodiments, the first and third molding portions  112 ,  122  can be any desired arrangement or combination of concave surfaces and convex surfaces. The second and fourth molding portions  111 ,  121  are flat surfaces. 
     In a ready position (molding position), the third molding portions  122  align with the first molding portions  112 , and the fourth molding portions  121  align with the second molding portions  111 . A maximum space T 2  is maintained between each first molding portion  112  and the corresponding third molding portion  122 , and a space T 1  is maintained between each second molding portion  111  and the corresponding fourth molding portion  121 . The first and third molding portions  112 ,  122  are configured for molding central optical portions  202  of the lenses  200 , and the second and fourth molding portions  111 ,  121  are configured for molding peripheral portions  201  of the lenses  200 . That is, the chamber  130  can mold a plurality or even a multiplicity of lenses  200  in a single molding cycle. 
     One or more sprues (not shown) for injecting lens material into the chamber  130  can be defined in positions in the first mold core  110 , or in positions adjacent to the chamber  130 . For example, one sprue can be defined for each group of four adjacent first molding portions  112 , with the sprue located in the first mold core  110  between the four first molding portions  112 . In order to ensure quality of all the lenses  200  made at a same time, a length D 1  of each of the first and third molding portions  112 ,  122  is preferably in a range from 1 millimeter to 1 centimeter, a minimum length D 2  of each of the second and fourth molding portions  111 ,  121  between each two adjacent first and third molding portions  112 ,  122  is preferably in a range from 2 millimeters to 1 centimeter, the maximum space T 1  between the first molding portions  112  and the third molding portions  122  is in a range from 1 millimeter to 1 centimeter, and the space T 2  between the second molding portions  111  and the fourth molding portions  121  is in a range from 0.4 millimeters and 2 millimeters. That is, the chamber  130  is preferably used for molding a plurality of small sized lenses  200 . 
     In a typical molding process using the mold  100 , first, uncured lens material is injected into the chamber  130  at an injection rate of about 1000 millimeters per second or more. This high injection rate is to ensure that the entire chamber  130  can be fully filled with the lens material. Then, the lens material is cooled. Next, the first mold core  110  is separated from the second mold core  120 , and the lens array  150  is ejected from second mold core  120 . After that, the lens array  150  can be diced to obtain a plurality of discrete lenses  200 . 
     The central optical portion  202  of each lens  200  in the lens array  150  has two convex surfaces  203 ,  204 , which correspond to the first molding portion  112  and the third molding portion  122 , respectively. For each two adjacent lenses  200 , whether in a row or a column of the matrix, a part of the peripheral portion  201  of one of the lenses  200  is shared with a part of the peripheral portion  201  of the other lens  200 . In this way, when the lens array  150  is diced at the peripheral portions  201 , for example, the plurality of discrete lenses  200  can be obtained. 
     It is understood that the above-described embodiments are intended to illustrate rather than limit the invention. Variations may be made to the embodiments and methods without departing from the spirit of the invention. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the invention.