Patent Publication Number: US-2012027978-A1

Title: Multi-element optical substrate and its preparation method, lens module using the multi-element optical substrate

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to optical substrate technology and more particularly, to a multi-element optical substrate and its preparation method. The invention relates also to an optical module using the multi-element optical substrate. 
     2. Description of the Related Art 
     Normally, an optical substrate has its function block located on the center area, and its border area used for mounting or decoration purpose. Using one single expensive material to make an optical substrate, the manufacturing cost will be high. There, multi-element optical substrates are developed. 
     However, when molding one element on another element to form a multi-element optical substrate, due to the existence of mold member precision tolerance, the two elements may not have the same optical center. Thus, when one element of a multi-element optical substrate is used for position calibration during installation, the optical center of the second element will not be accurately positioned, lowering the optical performance. 
     Therefore it is desirable to provide a multi-element optical substrate preparation method that eliminates the aforesaid problem. 
     SUMMARY OF THE INVENTION 
     The present invention has been accomplished under the circumstances in view. It is the main object of the present invention to provide a multi-element optical substrate and its preparation method, which enables a predetermined part of a first element to work as a positioning reference, and then mold a second element on the first element to have the optical center of the second element to be accurately obtained subject to the positioning reference so that an accurate optical center alignment effect can be obtained when the multi-element optical substrate is assembled with other components. 
     To achieve this and other objects of the present invention, a multi-element optical substrate preparation method includes the steps of: a) preparing a first element having a center hole and a core positioning device defining a first element center line; b) preparing a mold having a mold cavity and a cavity center line, and then placing the first element in the mold to keep a predetermined part of the first element in contact with the mold cavity; c) calibrating the position of the core positioning device of the first element in the mold cavity subject to the reference of the cavity center line of the mold; d) filling a transparent plastic material into the mold cavity of the mold for enabling the transparent plastic material to be molded on the first element and cured into a second element so that the first element and the second element form an optical substrate; and e) opening the mold and taking the optical substrate out of the mold. 
     The invention also provides a lens module having installed therein a multi-element optical substrate prepared according to the aforesaid preparation method. 
     To achieve this and other objects of the present invention, a multi-element optical substrate comprises a first element having a center hole and a core positioning device defining a first element center line. And a second element molded on the first element and connected to the center hole of the first element. The second element defines a second element center line that is determined subject to the reference of the core positioning device of the first element. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic sectional view of a first element for multi-element optical substrate in accordance with a first embodiment of the present invention. 
         FIG. 2  is a schematic sectional view showing the first element set in a mold in accordance with the first embodiment of the present invention. 
         FIG. 3  corresponds to  FIG. 2 , showing a transparent plastic material filled in the mold cavity of the mold. 
         FIG. 4  is a sectional view of a finished multi-element optical substrate in accordance with the first embodiment of the present invention. 
         FIG. 5  is a schematic sectional view of a first element for multi-element optical substrate in accordance with a second embodiment of the present invention. 
         FIG. 6  is a schematic sectional view showing the first element set in a mold in accordance with the second embodiment of the present invention. 
         FIG. 7  corresponds to  FIG. 6 , showing a transparent plastic material filled in the mold cavity of the mold. 
         FIG. 8  is a sectional view of a finished multi-element optical substrate in accordance with the second embodiment of the present invention. 
         FIG. 9  is a schematic sectional view of a first element for multi-element optical substrate in accordance with a third embodiment of the present invention. 
         FIG. 10  is a schematic sectional view showing the first element set in a mold in accordance with the third embodiment of the present invention. 
         FIG. 11  corresponds to FIG.  1 -, showing a transparent plastic material filled in the mold cavity of the mold. 
         FIG. 12  is a sectional view of a finished multi-element optical substrate in accordance with the third embodiment of the present invention. 
         FIG. 13  is a sectional assembly view of a lens module made according to the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The advantages and features of the present invention will be understood by reference to the following specification in conjunction with the accompanying drawings, in which like reference signs denote like elements of structure, in which, please refer to  FIGS. 1˜4 , a multi-element optical substrate preparation method in accordance with a first embodiment of the present invention includes the steps of: 
     a) preparing a first element  10  that has a bottom wall  15 , a top wall  16 , a center hole  11  cut through the top and bottom walls  15 ; 16 , an outer race  13  that forms a core positioning device defining a first element center line L 1 , and an inner race  14 ; 
     b) preparing a mold M having a mold cavity M 0  and a cavity center line L 0 , and then placing the first element  10  in the mold M to keep a predetermined part of the first element  10  in contact with the mold cavity M 0 ; 
     c) calibrating the position of the core positioning device of the first element  10  in the mold cavity M 0  subject to the reference of the cavity center line L 0  of the mold M by using a core positioning tool C; 
     d) filling a transparent plastic material  20 M into the mold cavity M 0  of the mold M for enabling the transparent plastic material  20 M to be molded on the first element  10  and cured into a second element  20  so that the first element  10  and the second element  20  form an optical substrate  1 , wherein filling of the transparent plastic material  20 M can be achieved by spot-gluing, injection or extrusion; wherein the second element  20  and the first element  10  are joined together in a butt joint manner; wherein the transparent plastic material  20 M is a light-curing or cold-curing material; and 
     e) opening the mold M and taking the optical substrate  1  out of the mold M. 
     According to this first embodiment, the center line L 1  of the first element  10  is coincided with the cavity center line L 0  of the mold M. 
     Based on the aforesaid steps, the invention provides an optical substrate  1 , comprising a first element  10  and a second element  20 . The second element  20  comprises a first element connection portion  24 , a bottom wall  25  and a top wall  26 . The bottom wall  25  and the top wall  26  define a second element&#39;s center line L 2  that is coincided with the center line L 1  of the first element  10 . 
     Thus, when the outer race  13  of the first element  10  is fastened to another component (for example, lens module), the second element&#39;s center line L 2  of the second element  20  is accurately kept in axial alignment with the axis to be set, assuring an accurate optical projection effect. 
     Referring to  FIGS. 5˜8 , a multi-element optical substrate preparation method in accordance with a second embodiment of the present invention is substantially similar to the aforesaid first embodiment. A multi-element optical substrate  1 A prepared in accordance this second embodiment, comprises a first element  10 A and a second element  20 A. The second element  20 A and the first element  10 A are joined together in a lap joint manner, i.e., the first element connection portion  24 A of the second element  20 A is bonded to a top wall  16 A of the first element  10 A. 
     Further, when calibrating the position of the first element center line L 1  based on the cavity center line L 0  of the mold MA, the core positioning tool C is positioned on the inner race  14 A of the first element  10 A. It is to be understood that the core positioning device can be positioned on the outer race  13 A (not shown) as the aforesaid first step, or positioned on both the outer race and the inner race. 
     Further, the mold cavity of the mold MB is located on the second mold member M 2 B, facilitating positioning and/or molding. 
     Referring to  FIGS. 9˜12 , a multi-element optical substrate preparation method in accordance with a third embodiment of the present invention is substantially similar to the aforesaid first and second embodiments. A multi-element optical substrate  1 B prepared in accordance this third embodiment, comprises a first element  10 B and a second element  20 B, wherein the first element  10 B has a peripheral cover member  30 B packed on the outer race  13 B. 
     According to this third embodiment, the periphery  32 B of the peripheral cover member  30 B of the first element  10 B works as the core positioning device to have the center axis of the first element  10 B be positioned on the device at the peripheral cover member  30 B. 
     Further, the cavity center line L 0  for calibrating the position of the second element&#39;s center line L 2  is disposed in parallel to the first element center line L 1 , thus, another multi-element optical substrate is obtained where the second element&#39;s center line L 2  can be accurately positioned relative to the first element center line L 1 . 
     Further, the mold MB in accordance with this third embodiment has an added more core M 3 B. 
     In conclusion, based on the aforesaid preparation methods, a multi-element optical substrate comprises: 
     a first element  10 ; 10 A; 10 B, having a center hole  11  and a core positioning device that defines a first element center line L 1 ; and 
     a second element  20 ; 20 A; 20 B connected to the center hole  11  of the first element  10 ; 10 A; 10 B and cured and bonded to the first element  10 ; 10 A; 10 B; 
     wherein the second element&#39;s center line L 2  is determined subject to the reference of the core positioning device of the first element  10 ; 10 A; 10 B. 
     Further, the invention provides a lens module  100  having installed therein a multi-element optical substrate  1 C, wherein the first element  10 C of the multi-element optical substrate  1 C is mounted in the lens barrel of the lens module in front of other lens elements of the lens module; the second element  20 C is in axial alignment with an aperture of the lens barrel, as shown in  FIG. 13 . 
     The above described embodiments are simple examples of the present invention. The preparation steps, materials used and structures of elements may be alternatively changed. Further, each of the aforesaid embodiments may be modified subject to the following modifications and their combinations. 
     At first, except having an outer race and an inner race, the first element has its inner race to work as the core positioning device. 
     Thereafter, the filling of the plastic material can be achieved by means of spot-gluing, injection or extrusion. 
     Further, except that the second element must be prepared from a light transmission material, the first element can be prepared from a light transmission material, a translucent material or an opaque material. Thus, invention facilitates material selection, saving the cost. When a translucent or opaque material is used for the first element, the material provides a light shielding effect. Further, the first element and the second element can be prepared from glass, or temperature-resistant resin that resists temperature 300˜500° C. and can be made by means of injection molding. 
     Further, the second element can be a convex lens or concave lens. 
     Further, the cavity center line of the mold and the center line of the first element can be coincided with each other, arranged in a parallel manner, or tiled relative to each other to define a contained angle. 
     Further, the center line of the second element and the center line of the first element can be coincided with each other, arranged in a parallel manner, or tiled relative to each other to define a contained angle. 
     In general, the present invention having been thus described with particular reference to the preferred embodiments thereof, it will be understood that in a multi-element optical substrate and its preparation method according to the present invention, a predetermined part of a first element works as a positioning reference, a second element is formed and bonded to the first element to have the optical center of the second element be accurately obtained subject to the positioning reference of the first element. Thus, after installation of the multi-element optical substrate in another component, an accurate optical center alignment effect is obtained. 
     Although particular embodiments of the invention have been described in detail for purposes of illustration, various modifications and enhancements may be made without departing from the spirit and scope of the invention. Accordingly, the invention is not to be limited except as by the appended claims.