Patent Publication Number: US-2012038839-A1

Title: Micro projector module

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims the priority benefit of Taiwan Patent Application Serial Number 099215553 filed Aug. 13, 2010, the full disclosure of which is incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a micro projector module, and more particularly, to a micro projector module with a stacked structure. 
     2. Description of the Related Art 
     In general, the controller chip and LCOS chip of a conventional micro projector module are commonly arranged on different positions on a substrate. This will increase the production cost and decrease the available space on the substrate accordingly. 
     Accordingly, there exists a need to provide a solution to solve the above-mentioned problems. 
     SUMMARY OF THE INVENTION 
     The present invention provides a micro projector module of which the LCOS chip is positioned on the controller chip package or directly on the unpackaged controller chip thereby increasing the available space on the substrate. 
     In one embodiment, the micro projector module of the present invention includes a substrate, a controller chip, a LCOS chip, a glass and a liquid crystal layer. The controller chip is positioned on the upper surface of the substrate and electrically connected to the substrate. The LCOS chip is positioned on the controller chip and electrically connected to the substrate. The glass is positioned on the LCOS chip and the liquid crystal layer is disposed between the LCOS chip and glass. 
     The foregoing, as well as additional objects, features and advantages of the invention will be more readily apparent from the following detailed description, which proceeds with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross-sectional view of the micro projector module according to the first embodiment of the present invention. 
         FIG. 2  is a top view of a substrate, wherein the substrate has a slot positioned thereon into which the micro projector modules of the present invention can be inserted. 
         FIG. 3  is a cross-sectional view of the micro projector module according to the second embodiment of the present invention. 
         FIG. 4  is a cross-sectional view of the micro projector module according to the third embodiment of the present invention. 
         FIG. 5  is a cross-sectional view of the micro projector module according to the fourth embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to  FIG. 1 , the micro projector module  100  according to the first embodiment of the present invention includes a substrate  110  and a controller chip package  120  is positioned on the upper surface  112  of the substrate  110  and electrically connected to the substrate  110 . In this embodiment, the controller chip package  120  can be a land grid array (LGA) package, ball grid array (BGA) package, quad flat non-leaded (QFN) package or other type packages. A liquid crystal on silicon (LCOS) chip  130  is attached to the controller chip package  120  by adhesive. A plurality of bonding wires  140  is used to electrically connect the LCOS chip  130  to the substrate  110 . In order to prevent the bonding wires  140  from damage, a sealant  180  is formed on the upper surface  112  of the substrate  110  to encapsulate the bonding wires  140 . A transparent glass  150  is positioned on the LCOS chip  130  and protrudes from an edge  132  of the LCOS chip  130 . A liquid crystal layer is disposed between the glass  150  and LCOS chip  130  (not shown in the figure). In addition, a conductive block  160  is formed under the glass  150  and aside the edge  132  of the LCOS chip  130 . A conductive adhesive  170  is formed on the conductive block  160  to electrically connect the glass  150  to the conductive block  160 . 
     In order to enable the controller chip package  120  to electrically connect to external circuitry, a connector  190  is positioned on the lower surface  114  of the substrate  110 . The connector  190  can be inserted into, for example, the slot  290  on the substrate  210  of  FIG. 2 . In addition, a plurality of passive components  195  is positioned on the lower surface  114  of the substrate  110  to enable the micro projector module  100  to function well. 
     Referring to  FIG. 3 , the micro projector module  300  according to the second embodiment of the present invention is similar to the micro projector module  100  according to the first embodiment of the present invention, where identical reference numerals have been used when designating substantially identical elements that are common to the figures. The differences between them are in that the micro projector module  300  has a controller chip package  320  that is a wire-bonding type package. More specifically, the controller chip package  320  includes a substrate  321  and a controller chip  325  is attached to the upper surface  322  of the substrate  321  by adhesive. A plurality of bonding wires  324  electrically connects the controller chip  325  to the substrate  321 . A sealant  326  is formed on the upper surface  322  of the substrate  321  to encapsulate the controller chip  325  and bonding wires  324 . In addition, a plurality of metal bumps  327 , such as solder balls is positioned on the lower surface  323  of the substrate  321  to electrically connect the controller chip  325  to the substrate  110 . Furthermore, because the other elements of the micro projector module  300  and their connecting relations are the same as those of the micro projector module  100 , any further illustrations of the micro projector module  300  are omitted herein. 
     Referring to  FIG. 4 , the micro projector module  400  according to the third embodiment of the present invention is similar to the micro projector module  100  according to the first embodiment of the present invention, where identical reference numerals have been used when designating substantially identical elements that are common to the figures. The differences between them are in that the micro projector module  400  has a controller chip  420  that is not packaged in advance. Instead, the controller chip  420  is flip-chip bonded on the substrate  110 . A plurality of metal bumps  427 , such as solder balls is used to electrically connect the controller chip  420  to the substrate  110 . The LCOS chip  130  is then attached to the backside of the controller chip  420 . Furthermore, because the other elements of the micro projector module  400  and their connecting relations are the same as those of the micro projector module  100 , any further illustrations of the micro projector module  400  are omitted herein. 
     Referring to  FIG. 5 , the micro projector module  500  according to the fourth embodiment of the present invention is similar to the micro projector module  100  according to the first embodiment of the present invention, where identical reference numerals have been used when designating substantially identical elements that are common to the figures. The differences between them are in that the micro projector module  500  has a controller chip  520  that is bonded on the upper surface  112  of the substrate  110  by COB technique. More specifically, the unpackaged controller chip  520  is attached to the upper surface  112  of the substrate  110  by adhesive and a plurality of bonding wires  522  is used to electrically connect the controller chip  520  to the substrate  110 . A sealant  524  is formed on the upper surface  112  of the substrate  110  to encapsulate the controller chip  520  and bonding wires  522 . The LCOS chip  130  is then attached to the sealant  524 . Furthermore, because the other elements of the micro projector module  500  and their connecting relations are the same as those of the micro projector module  100 , any further illustrations of the micro projector module  500  are omitted herein. 
     According to the micro projector module of the present invention, the LCOS chip is positioned on the controller chip package or directly on the unpackaged (bare) controller chip thereby increasing the available space on the substrate. 
     Although the preferred embodiments of the invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.