PATENT DOCUMENT

Publication Number: US-8902352-B2
Application Number: US-201213631642-A
Country: US
Kind Code: B2

Title: Lens barrel mechanical interference prevention measures for camera module voice coil motor design

Abstract:
A camera module has an image sensor and a lens assembly that includes a lens barrel having a first cylindrical portion that includes an externally threaded portion and a second cylindrical portion that has a larger diameter than the externally threaded portion. A lens moving mechanism includes a movable sleeve having internal threads that receive the externally threaded portion of the lens assembly. The lens moving mechanism is coupled to the image sensor such that the second cylindrical portion of the lens assembly is closest to the image sensor. The camera module is assembled by inserting the lens assembly into the lens moving mechanism from the side closest to the image sensor. An installation tool may engage the second cylindrical portion to rotate the lens assembly and engage the threaded portions. Features may be provided to retain the lens assembly in the lens moving mechanism before joining the threaded portions.

Claims:
What is claimed is: 
     
       1. A camera module comprising:
 a lens assembly that includes a lens barrel having a first cylindrical portion that includes an externally threaded portion and a second cylindrical portion that has a larger diameter than the externally threaded portion; 
 an external cylindrical surface on the second cylindrical portion of the lens assembly; 
 at least one protruding tab included on the external cylindrical surface; 
 an image sensor; 
 a lens moving mechanism that includes a movable sleeve having internal threads that receive the externally threaded portion of the lens assembly, the lens moving mechanism being coupled to the image sensor such that the second cylindrical portion of the lens assembly is closest to the image sensor, the lens moving mechanism having an opening to receive the lens assembly that requires alignment of the at least one protruding tab to a corresponding recess in the opening of the lens moving mechanism. 
 
     
     
       2. The camera module of  claim 1  wherein the lens assembly includes at least two lenses, one lens being mounted in the second cylindrical portion of the lens assembly. 
     
     
       3. The camera module of  claim 1  wherein the lens moving mechanism is a voice coil motor. 
     
     
       4. The camera module of  claim 1  wherein the protruding tab is chamfered to have a width of a top surface of the protruding tab that is narrower than a width of a bottom surface of the protruding tab such that force is required to insert the protruding tab past the corresponding recess in the opening of the lens moving mechanism. 
     
     
       5. The camera module of  claim 1  wherein the corresponding recess in the opening of the lens moving mechanism is chamfered to have a width of a top opening that is narrower than a width of a bottom opening such that force is required to insert the protruding tab past the corresponding recess in the opening of the lens moving mechanism. 
     
     
       6. The camera module of  claim 1  further comprising a retaining structure that is attached to the lens moving mechanism after the lens assembly is received in the lens moving mechanism to reduce a diameter of the opening to be less than a diameter of the lens assembly. 
     
     
       7. The camera module of  claim 1  further comprising a substrate to which the image sensor is attached and a protective structure attached to the substrate at a location where the protective structure prevents the lens assembly from contacting the image sensor when not engaged with the lens moving mechanism. 
     
     
       8. A camera module comprising:
 a lens assembly that includes a lens barrel having a first cylindrical portion that includes an externally threaded portion and a second cylindrical portion that has a larger diameter than the externally threaded portion; 
 an external cylindrical surface on the second cylindrical portion of the lens assembly; 
 a plurality of protruding tabs arranged asymmetrically on the external cylindrical surface; 
 an image sensor; and 
 a lens moving mechanism that includes a movable sleeve having internal threads that receive the externally threaded portion of the lens assembly, the lens moving mechanism being coupled to the image sensor such that the second cylindrical portion of the lens assembly is closest to the image sensor, the lens moving mechanism having an opening to receive the lens assembly that requires alignment of the plurality of protruding tabs to corresponding recesses in the opening of the lens moving mechanism such that the lens assembly is received in the opening of the lens moving mechanism in only one angular position. 
 
     
     
       9. The camera module of  claim 8  wherein the lens assembly includes at least two lenses, one lens being mounted in the second cylindrical portion of the lens assembly. 
     
     
       10. The camera module of  claim 8  wherein the lens moving mechanism is a voice coil motor. 
     
     
       11. The camera module of  claim 8  wherein the plurality of protruding tabs are each chamfered to have a width of a top surface of the protruding tab that is narrower than a width of a bottom surface of the protruding tab such that force is required to insert the plurality of protruding tabs past the corresponding recesses in the opening of the lens moving mechanism. 
     
     
       12. The camera module of  claim 8  wherein the corresponding recesses in the opening of the lens moving mechanism are each chamfered to have a width of a top opening that is narrower than a width of a bottom opening such that force is required to insert the protruding tab past the corresponding recesses in the opening of the lens moving mechanism. 
     
     
       13. The camera module of  claim 8  further comprising a retaining structure that is attached to the lens moving mechanism after the lens assembly is received in the lens moving mechanism to reduce a diameter of the opening to be less than a diameter of the lens assembly. 
     
     
       14. The camera module of  claim 8  further comprising a substrate to which the image sensor is attached and a protective structure attached to the substrate at a location where the protective structure prevents the lens assembly from contacting the image sensor when not engaged with the lens moving mechanism. 
     
     
       15. A camera module comprising:
 a lens assembly that includes a lens barrel having a first cylindrical portion that includes an externally threaded portion and a second cylindrical portion that has a larger diameter than the externally threaded portion; 
 an image sensor; 
 a lens moving mechanism that includes a movable sleeve having internal threads that receive the externally threaded portion of the lens assembly, the lens moving mechanism being coupled to the image sensor such that the second cylindrical portion of the lens assembly is closest to the image sensor, the lens moving mechanism having an opening to receive the lens assembly; and 
 a retaining structure that is attached to the lens moving mechanism after the lens assembly is received in the lens moving mechanism to reduce a diameter of the opening to be less than a diameter of the lens assembly. 
 
     
     
       16. The camera module of  claim 15  wherein the lens assembly includes at least two lenses, one lens being mounted in the second cylindrical portion of the lens assembly. 
     
     
       17. The camera module of  claim 15  wherein the lens moving mechanism is a voice coil motor. 
     
     
       18. The camera module of  claim 15  wherein an external cylindrical surface of the second cylindrical portion of the lens assembly includes at least one protruding tab and the opening to receive the lens assembly requires alignment of the protruding tab to a corresponding recess in the opening of the lens moving mechanism. 
     
     
       19. The camera module of  claim 18  wherein the protruding tab is chamfered to have a width of a top surface of the protruding tab that is narrower than a width of a bottom surface of the protruding tab such that force is required to insert the protruding tab past the corresponding recess in the opening of the lens moving mechanism. 
     
     
       20. The camera module of  claim 18  wherein the corresponding recess in the opening of the lens moving mechanism is chamfered to have a width of a top opening that is narrower than a width of a bottom opening such that force is required to insert the protruding tab past the corresponding recess in the opening of the lens moving mechanism. 
     
     
       21. The camera module of  claim 15  further including a plurality of protruding tabs that are arranged asymmetrically on an external cylindrical surface of the second cylindrical portion of the lens assembly and a plurality of corresponding recesses in the opening of the lens moving mechanism that require alignment of the plurality of protruding tabs to the plurality of corresponding recesses such that the lens assembly is received in the opening of the lens moving mechanism in only one angular position. 
     
     
       22. The camera module of  claim 15  further comprising a substrate to which the image sensor is attached and a protective structure attached to the substrate at a location where the protective structure prevents the lens assembly from contacting the image sensor when not engaged with the lens moving mechanism. 
     
     
       23. A camera module comprising:
 a lens assembly that includes a lens barrel having a first cylindrical portion that includes an externally threaded portion and a second cylindrical portion that has a larger diameter than the externally threaded portion; 
 an image sensor; 
 a lens moving mechanism that includes a movable sleeve having internal threads that receive the externally threaded portion of the lens assembly, the lens moving mechanism being coupled to the image sensor such that the second cylindrical portion of the lens assembly is closest to the image sensor; 
 a substrate to which the image sensor is attached; and 
 a protective structure attached to the substrate at a location where the protective structure prevents the lens assembly from contacting the image sensor when not engaged with the lens moving mechanism. 
 
     
     
       24. The camera module of  claim 23  wherein the lens assembly includes at least two lenses, one lens being mounted in the second cylindrical portion of the lens assembly. 
     
     
       25. The camera module of  claim 23  wherein the lens moving mechanism is a voice coil motor. 
     
     
       26. The camera module of  claim 23  wherein an external cylindrical surface of the second cylindrical portion of the lens assembly includes at least one protruding tab and the lens moving mechanism has an opening to receive the lens assembly that requires alignment of the protruding tab to a corresponding recess in the opening of the lens moving mechanism. 
     
     
       27. The camera module of  claim 26  wherein the protruding tab is chamfered to have a width of a top surface of the protruding tab that is narrower than a width of a bottom surface of the protruding tab such that force is required to insert the protruding tab past the corresponding recess in the opening of the lens moving mechanism. 
     
     
       28. The camera module of  claim 26  wherein the corresponding recess in the opening of the lens moving mechanism is chamfered to have a width of a top opening that is narrower than a width of a bottom opening such that force is required to insert the protruding tab past the corresponding recess in the opening of the lens moving mechanism. 
     
     
       29. The camera module of  claim 23  further including a plurality of protruding tabs that are arranged asymmetrically on an external cylindrical surface of the second cylindrical portion of the lens assembly and the lens moving mechanism has an opening to receive the lens assembly that requires alignment of the plurality of protruding tabs to corresponding recesses in the opening of the lens moving mechanism such that the lens assembly is received in the opening of the lens moving mechanism in only one angular position. 
     
     
       30. The camera module of  claim 23  wherein the lens moving mechanism has an opening to receive the lens assembly and further comprising a retaining structure that is attached to the lens moving mechanism after the lens assembly is received in the lens moving mechanism to reduce a diameter of the opening to be less than a diameter of the lens assembly.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit pursuant to 35 U.S.C. 119(e) of U.S. Provisional Application No. 61/657,620, filed Jun. 8, 2012, which application is specifically incorporated herein, in its entirety, by reference. 
    
    
     BACKGROUND 
     1. Field 
     Embodiments of the invention relate to the field of camera lens modules; and more specifically, to a camera module for use in portable digital devices. 
     2. Background 
     Many portable electronic devices, such as mobile cellular telephones, include a digital camera. The lenses for such cameras must be compact to fit within the case of the portable electronic device. At the same time there is a desire to provide an increasingly high quality camera function in these devices. To provide a higher quality image, some cameras found in portable electronic devices provide an autofocus feature. 
     The lens may be mounted in a mechanism that moves the lens along its optical axis to change the distance between the lens and the image sensor. This changes the focal distance of the camera and allows a sharper image to be obtained for subjects over a greater range of distances from the camera. One such lens moving mechanism for moving a lens is a voice coil motor (VCM). 
     Typically a lens is inserted into a lens moving mechanism, such as a VCM, and an image sensor is then assembled to the lens moving mechanism to provide a camera lens module. The module is assembled in clean room conditions so that dust is not trapped between the lens and the image sensor. The assembled camera lens module provides all the optical components in a single package that can be assembled into the portable electronic device. 
     Typically the lens will be joined to the lens moving mechanism by screw threads. The assembly is difficult because the lens and the lens moving mechanism are fairly delicate and the assembly must be done without exerting excessive forces on the lens or the mechanism, either axially or rotationally. The small size of the parts further complicates the assembly. A typical lens used in a portable electronic device may have a diameter of about 0.25 inches (6.5 millimeters). 
     A VCM for a camera module applications is a highly space constrained device. The demand for improved optics in camera module applications requires larger, heavier, lens components to be integrated within a VCM. A lens barrel is integrated within the VCM containing optical components of a lens system. Typically a cylindrical lens barrel is threaded in place within the carrier or holder of a VCM from the top opening furthest from the imaging plane. Typically the largest lens element within an optical system is the last element closest to the imaging plane. 
     It would be desirable to provide lens insertion methods and structures that allow the camera lens module to be reduced in size. 
     SUMMARY 
     A camera module has an image sensor and a lens assembly that includes a lens barrel having a first cylindrical portion that includes an externally threaded portion and a second cylindrical portion that has a larger diameter than the externally threaded portion. A lens moving mechanism includes a movable sleeve having internal threads that receive the externally threaded portion of the lens assembly. The lens moving mechanism is coupled to the image sensor such that the second cylindrical portion of the lens assembly is closest to the image sensor. The camera module is assembled by inserting the lens assembly into the lens moving mechanism from the side closest to the image sensor. An installation tool may engage the second cylindrical portion to rotate the lens assembly and engage the threaded portions. Features may be provided to retain the lens assembly in the lens moving mechanism before joining the threaded portions. 
     Other features and advantages of the present invention will be apparent from the accompanying drawings and from the detailed description that follows below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention may best be understood by referring to the following description and accompanying drawings that are used to illustrate embodiments of the invention by way of example and not limitation. In the drawings, in which like reference numerals indicate similar elements: 
         FIG. 1  is a cross-sectional view of the components of a camera module in an unassembled configuration. 
         FIG. 2  is a cross-sectional view of the camera module of  FIG. 1  in an assembled configuration. 
         FIG. 3  is a pictorial view of the camera module of  FIG. 1  in an unassembled configuration. 
         FIGS. 4A and 4B  are pictorial views of another camera module in an unassembled configuration with a tool for assembling the lens assembly to the lens moving mechanism. 
         FIG. 5  is a side view of the camera module of  FIGS. 4A and 4B  in an assembled configuration with the tool for assembling the lens assembly to the lens moving mechanism. 
         FIG. 6  is a cross-sectional view of the camera module taken along section line  6 - 6  in  FIG. 5 . 
         FIG. 7  is a pictorial view of another lens assembly with another tool for assembling the lens assembly to the lens moving mechanism. 
         FIG. 8  is a pictorial view of another lens assembly with another tool for assembling the lens assembly to the lens moving mechanism. 
         FIG. 9  is a cross-sectional view of the tool of  FIG. 8  engaging the lens assembly. 
         FIG. 10  is a pictorial view of another lens assembly with another tool for assembling the lens assembly to the lens moving mechanism. 
         FIG. 11  is a cross-sectional view of the tool of  FIG. 10  engaging the lens assembly. 
         FIG. 12  is a cross-sectional view of the components of a camera module in an unassembled configuration. 
         FIG. 13  is a cross-sectional view of the camera module of  FIG. 12  in a partially assembled configuration. 
         FIG. 14  is a cross-sectional view of the camera module of  FIG. 12  in a fully assembled configuration. 
         FIG. 15  is an end view of the opening of the lens moving mechanism from the camera module of  FIG. 12 . 
         FIG. 16  is an end view of the opening of the lens moving mechanism from another camera module. 
         FIG. 17  is an end view of the opening of the lens moving mechanism from yet another camera module. 
         FIG. 18  is a cross-sectional view of another embodiment of a tab and a corresponding recess. 
         FIG. 19  is a cross-sectional view of yet another embodiment of a tab and a corresponding recess. 
         FIG. 20  is a cross-sectional view of the components of another camera module in an unassembled configuration. 
         FIG. 21  is a cross-sectional view of the camera module of  FIG. 20  in an assembled configuration. 
         FIG. 22  is a plan view of a retaining structure with a bottom end of a lens assembly. 
         FIG. 23  is a cross-sectional view of yet another camera module in an assembled configuration. 
     
    
    
     DETAILED DESCRIPTION 
     This disclosure describes methods for constraining a bottom side assembly lens barrel from mechanical interference with underlying structures within a camera module system. 
     In the following description, numerous specific details are set forth. However, it is understood that embodiments of the invention may be practiced without these specific details. In other instances, well-known circuits, structures and techniques have not been shown in detail in order not to obscure the understanding of this description. 
       FIG. 1  is a cross-sectional view of the components of a camera module in an unassembled configuration.  FIG. 2  is a cross-sectional view of the camera module  200  of  FIG. 1  in an assembled configuration.  FIG. 3  is a pictorial view of the camera module of  FIG. 1  in an unassembled configuration. 
     The camera module shown in  FIGS. 1-3  includes a lens moving mechanism  100 , which may be a voice coil motor (VCM). The lens moving mechanism  100  includes a movable sleeve  104  having internal threads  102 . The lens moving mechanism  100  provides means for moving the movable sleeve  104  axially in the direction shown by the two-headed arrow  106 . A particular means for moving the movable sleeve  104  is not shown and any such means may be used. 
     The camera module further includes a lens assembly that includes two or more lenses  112 ,  114  mounted in a lens barrel  110 . The lens barrel designs achieve space efficiency within the lens moving mechanism by adopting a non-cylindrical shape. The lens barrels is designed with a chamfer towards the bottom of the barrel, the larger flared bottom diameter of the lens barrel contains the larger lens element(s), whilst the smaller diameter lens elements are housed in the threaded upper portion of the lens barrel. This type of lens barrel design requires assembly by threading into the lens moving mechanism from the bottom side, rather than the conventional top side approach. When molding the carrier for a bottom assembly VCM, the inner threaded insert mold is designed to thread outwards from the bottom side of the carrier during tool release. The lens barrel is then assembled from this same end. 
     The lens barrel has a first cylindrical portion that includes an externally threaded portion  118  and a second cylindrical portion  116  that has a larger diameter than the externally threaded portion. This lens assembly differs from conventional lens assemblies in which the externally threaded portion has the largest diameter of any portion of the lens barrel. 
     The diameter of the second cylindrical portion  116  is selected to be just slightly larger than the largest diameter lens  114  in the lens assembly. This lens  114  will be the lens closest to an image sensor  120 . Providing a second cylindrical portion  116  that has a larger diameter than the externally threaded portion  118  allows the lens moving mechanism  100  to be more compact because the internal threads  102  of the movable sleeve  104  do not have to have a diameter that can accommodate the second cylindrical portion  116 . However this creates a difficulty in assembling the camera module  200 . 
     Typically a lens assembly is assembled to a lens moving mechanism by inserting the lens assembly into the lens moving mechanism from the side furthest from the image sensor. This requires that the entire portion of lens barrel below the externally threaded portion, including the portion supporting the largest diameter lens, pass through the internally threaded portion of a movable sleeve in the lens moving mechanism toward the image sensor. This allows the lens barrel to be held at the end furthest from the image sensor, the end which supports the smallest lens and which may be referred to as the front end of the lens assembly. 
     It will be appreciated that while a lens assembly may be described a moving in relation to an image sensor during assembly, such description is merely to establish the direction within the components of the camera module and the image sensor will likely not be present in the camera module when the lens assembly is assembled to the lens moving mechanism. Thus a description of a lens assembly advancing toward an image sensor during assembly should be understood to include advancing toward the place where an image sensor would be positioned in a fully assembled camera module. 
     The smallest lens at the front end of the lens assembly is much smaller in diameter than the outer diameter of the lens barrel. This allows engagement features to be provided in the front end of the lens barrel. An assembly tool can easily engage the engagement features and assemble the lens assembly to the internally threaded portion of the movable sleeve with the lens assembly advancing toward the image sensor as it is threaded into the movable sleeve. 
     In embodiments of the invention, the second cylindrical portion  116  has a larger diameter than the externally threaded portion  118  of the lens barrel, and the corresponding internally threaded portion  102  of the movable sleeve  104 . Therefore, a lens assembly  200  that embodies the invention cannot be assembled to the internally threaded portion  102  of the movable sleeve  104  with the lens assembly advancing toward the image sensor  120  as it is threaded into the movable sleeve. It is required that a lens assembly  200  that embodies the invention be assembled to the internally threaded portion  102  of the movable sleeve  104  with the lens assembly advancing away from the image sensor  120  as it is threaded into the movable sleeve. The lens assembly  200  must be assembled from the back side  108  of the lens moving mechanism  100 , which is the side that will be closest to the image sensor  120 . The image sensor  120  may be supported by a substrate  122  that is assembled to the lens moving mechanism  100  to complete the camera module  100 . 
     Assembling the lens assembly  200  from the back side  108  of the lens moving mechanism  100  requires the lens barrel  110  to be held at the end  116  closest to the image sensor, the end which supports the largest lens  114  and which may be referred to as the back end of the lens assembly. At the back end  116  of the lens assembly  200 , it is desirable to make the lens barrel  110  as small as possible to keep the camera module  100  compact. The back end  116  of the lens assembly  200  may have a diameter that is only 0.2 to 0.4 millimeters larger than the large lens  114  supported by the back end of the lens barrel. Thus the walls of the lens barrel  110  at the back end  116  may be only 0.1 to 0.2 millimeters. Further, the large lens  114  may need to approach to within 30 microns of an infrared cut filter (not shown) that is between the lens assembly  200  and the image sensor  120 . Therefore thickest portion of the rear surface of the large lens  114  must be approximately flush with the back end of the lens assembly  200 . This configuration makes it difficult to hold the lens assembly  200  for assembly to the lens moving mechanism  100  from the back side  108 . 
     A camera module that embodies the present invention may be assembled by inserting the lens assembly  110  into the lens moving mechanism  100  from the back side. The lens assembly  110  includes a lens barrel  110  having a first cylindrical portion that includes an externally threaded portion  118  and a second cylindrical portion  116  that has a larger diameter than the externally threaded portion. An installation tool is engaged with the second cylindrical portion  116  of the lens assembly  110 . A portion of the installation tool that engages the lens assembly has a diameter no greater than the diameter of the second cylindrical portion  116  of the lens assembly  110 . This permits the installation tool to pass through the back side of the lens moving mechanism  100  as necessary during the assembly process. The installation tool rotates the lens assembly  110  to engage the externally threaded portion  118  of the lens assembly  110  with the internally threaded portion  102  of the movable sleeve  104  of the lens moving mechanism  100 . The lens assembly  110  advances away from the image sensor  120  as it is threaded into the movable sleeve  104 . The image sensor  120  is coupled to the lens moving mechanism  100  such that the second cylindrical portion  116  of the lens assembly  110  is closest to the image sensor. 
       FIGS. 4A and 4B  are pictorial views of another camera module in an unassembled configuration with a tool  400  for assembling the lens assembly  410  to the lens moving mechanism  420 .  FIG. 5  is a side view of the camera module of  FIGS. 4A and 4B  in an assembled configuration with the tool  400  for assembling the lens assembly  410  to the lens moving mechanism  420 .  FIG. 6  is a cross-sectional view of the camera module taken along section line  6 - 6  in  FIG. 5 . 
     In this embodiment the tool  400  includes protrusions  402  that mechanically engage notches  412  provided in the second cylindrical portion  416  of the lens assembly  410  that is closest to the image sensor. A wall  406  of the tool  400  may fit the inside cylindrical surface to the lens assembly  410  adjacent the large lens  414  to provide support for the lens assembly  410  during the assembly process. The center portion  404  of the tool  400  is recessed to provide clearance that prevents the tool from touching the surface of the large lens  414 . 
     A vacuum may be used to hold the lens assembly  410  with the installation tool  400 . For example, a vacuum may be applied in the center portion  404  of the tool  400 . 
     The lens assembly  410  may include engagement features  418  at the front of the lens assembly. The engagement features  418  may be used to rotate the lens assembly  410  from the front side after the lens assembly  410  is initially engaged with the lens moving mechanism  420  from the back side. 
       FIG. 7  is a pictorial view of another lens assembly  710  with another tool  700  for assembling the lens assembly to a lens moving mechanism. In this embodiment, the tool has a flat surface  702  to engage the flat surface at the back of the second cylindrical portion  712  of the lens assembly  710 . 
     In some embodiments, the surface of the installation tool that engages the second cylindrical portion  712  of the lens assembly  710  may be a material having a high coefficient of static friction with the lens barrel material. For example, the coefficient of static friction may be greater than 0.6. 
     In some embodiments, a temporary adhesive may join the second cylindrical portion  712  of the lens barrel to the installation tool  700 . The lens barrel is separated from the installation tool  700  at the adhesive joint once the lens assembly  710  has been assembled. 
       FIG. 8  is a pictorial view of another lens assembly  810  with another tool  800  for assembling the lens assembly to the lens moving mechanism. This tool  800  includes a conical surface  802  that engages an inside surface of the second cylindrical portion  812  of the lens assembly  810 .  FIG. 9  is a cross-sectional view of the tool of  FIG. 8  engaging the inside surface of the second cylindrical portion  812  of the lens assembly  810 . The lens assembly  810  may provide a conical recess that the conical surface  802  of the installation tool presses against. A retaining ring  914  for the large lens  916  may provide the conical surface in the second cylindrical portion  812  of the lens assembly  810 . The conical surface may be advantages in that a greater pressure can be applied normal to the gripping surfaces without exceeding the allowable axial force applied to the lens moving mechanism. 
     The conical surface  802  of the installation tool  800  may be a resilient material. The conical surface  802  of the installation tool  800  may be a material having a high coefficient of static friction with the lens barrel material. For example, the coefficient of static friction may be greater than 0.6 
       FIG. 10  is a pictorial view of another lens assembly  1010  with another tool  1000  for assembling the lens assembly to the lens moving mechanism.  FIG. 11  is a cross-sectional view of the tool  1000  of  FIG. 10  engaging the lens assembly  1010 . In this embodiment, the inside surface of the second cylindrical portion  1012  of the lens assembly  1010  provides a recess and the installation tool  1000  provides a gripping section  1002  that expands to press against the recess. As illustrated the gripping section  1002  may be conical to engage a corresponding conical recess. In other embodiments not illustrated, the recess may be cylindrical with a surface parallel to an optical axis of the lens assembly and the tool may provide a cylindrical gripping section. 
     As may be seen in  FIG. 11 , the gripping section  1002  of the installation tool  1000  may be mechanically expanded to press against the recess in the second cylindrical portion  1012  of the lens assembly  1010 . For example, a plunger  1100  may be moved in an axial direction to expand the gripping section  1002  of the installation tool  1000 . 
     In other embodiments, the gripping section of the installation tool may be pneumatically expanded to press against the recess in the second cylindrical portion  1012  of the lens assembly  1010 . 
     In other embodiments, the gripping section of the installation tool may be hydraulically expanded to press against the recess in the second cylindrical portion  1012  of the lens assembly  1010 . 
     The gripping section  1002  of the installation tool  1000  may be a resilient material. The gripping section  1002  of the installation tool  1000  may be a material having a high coefficient of static friction with the lens barrel material. For example, the coefficient of static friction may be greater than 0.6. 
     In other embodiments, a vacuum may be applied to hold the lens assembly  1010  with the installation tool  1000 . The vacuum may cause the lens assembly  1010  to press against the gripping section  1002  of the installation tool  1000  and cause the gripping section to expand and press against the recess in the second cylindrical portion  1012  of the lens assembly. 
       FIG. 12  is a cross-sectional view of the components of another camera module in an unassembled configuration.  FIG. 13  is a cross-sectional view of the camera module of  FIG. 12  in a partially assembled configuration.  FIG. 14  is a cross-sectional view of the camera module of  FIG. 12  in a fully assembled configuration. 
     The camera module shown in  FIGS. 12-14  includes a lens moving mechanism  1200 , which may be a voice coil motor. The lens moving mechanism  1200  includes a movable sleeve  1204  having internal threads  1202 . The lens moving mechanism  1200  provides means for moving the movable sleeve  1204  axially in the direction shown by the two-headed arrow  1206 . A particular means for moving the movable sleeve  1204  is not shown and any such means may be used. 
     The camera module further includes a lens assembly that includes two or more lenses  1212 ,  1214  mounted in a lens barrel  1210 . The lens barrel has a first cylindrical portion that includes an externally threaded portion  1218  and a second cylindrical portion  1216  that has a larger diameter than the externally threaded portion. This lens assembly differs from conventional lens assemblies in which the externally threaded portion has the largest diameter of any portion of the lens barrel. 
     The diameter of the second cylindrical portion  1216  is selected to be just slightly larger than the largest diameter lens  1214  in the lens assembly. This lens  1214  will be the lens closest to an image sensor  1220 . Providing a second cylindrical portion  1216  that has a larger diameter than the externally threaded portion  1218  allows the lens moving mechanism  1200  to be more compact because the internal threads  1202  of the movable sleeve  1204  do not have to have a diameter that can accommodate the second cylindrical portion  1216 . However this creates a difficulty in assembling the camera module as previously described. 
     In the previously described bottom side assembly approach that assembles the lens barrel into the lens moving mechanism from end adjacent to the image sensor, there is a risk that the lens barrel will not be fully constrained in the vertical direction. Interference of the lens barrel with underlying components within the module or disengagement of the barrel threads could result. This could result in damage to camera module components, such as the image sensor, filters in the optical path, or the rearmost lens, during the assembly process or if the camera module is dropped after assembly. 
     In the embodiment shown in  FIGS. 12-14 , at least one protruding tab  1230  is included on an external cylindrical surface of the second cylindrical portion  1216  of the lens barrel  1210 . The lens moving mechanism  1200  has an opening  1232  to receive the lens assembly from the bottom side. The opening  1232  includes a recess  1234  to allow the protruding tab  1230  to pass through the opening. This requires alignment of the protruding tab  1230  to the corresponding recess  1234  in the opening  1232  of the lens moving mechanism  1200 . 
       FIG. 13  shows the camera module of  FIG. 12  in a partially assembled configuration. At this stage of the assembly process the protruding tab  1230  has pass through the corresponding recess  1234  in the opening  1232  of the lens moving mechanism  1200 . The movable sleeve  1204  provides sufficient clearance for the protruding tab  1230  to permit the lens barrel  1210  to be rotated freely. The protruding tab  1230  retains the lens barrel  1210  within the lens moving mechanism  1200  except for the angular position where the protruding tab  1230  is aligned to the corresponding recess  1234  in the opening  1232  of the lens moving mechanism  1200 . 
       FIG. 14  shows the camera module of  FIG. 12  in a fully assembled configuration. The movable sleeve  1204  provides sufficient clearance for the protruding tab  1230  to permit the lens barrel  1210  to be fully threaded into the movable sleeve  1204 . With the lens barrel  1210  retained in the lens moving mechanism  1200  by the protruding tab  1230 , it may be possible to assemble the substrate  1222 , which carries the image sensor  1220  and related components, to the back side  1208  of the lens moving mechanism  1200  and then rotating the lens barrel  1210  from the front side to thread the lens barrel into the movable sleeve  1204 . 
       FIG. 15  shows the opening  1232  of the lens moving mechanism of  FIG. 12  from the bottom end. In this embodiment there is a single recess  1234  in the opening  1232  to receive the protrusion on the lens barrel. 
       FIG. 16  shows the opening  1632  of the lens moving mechanism from the bottom end of another embodiment. In this embodiment there are three recesses  1634  in the opening  1632  to receive three corresponding protrusions on the lens barrel. The use of more than one protrusion may hold the lens in better alignment with the threaded portion of the movable sleeve. 
       FIG. 17  shows the opening  1732  of the lens moving mechanism from the bottom end of yet another embodiment. In this embodiment there are three recesses  1734 ,  1736 ,  1738  in the opening  1732  to receive three corresponding protrusions on the lens barrel. Unlike the embodiment shown in  FIG. 16  the recesses are arranged asymmetrically. For example, the angles between the recesses, and the corresponding protruding tabs on the lens assembly might be 110°, 120°, and 130°. It will be appreciated that the use of more than one protrusion and recess arranged symmetrically around the lens barrel increases the number of angular positions at which the lens barrel can pass through the opening thus making the lens barrel less secure in the lens moving mechanism. An asymmetric arrangement of protruding tabs and corresponding recesses allows the lens barrel to pass through the opening in only a single angular position thus increasing the security of the lens barrel in the lens moving mechanism. 
       FIG. 18  shows another embodiment of a tab and a corresponding recess. In this embodiment the corresponding recess  1834  in the opening of the lens moving mechanism is chamfered wherein the width of the top opening is narrower than the width of bottom opening such that force is required to insert the protruding tab  1830  past the corresponding recess  1834  in the opening of the lens moving mechanism. It will be appreciated that the protruding tab and/or the corresponding recess may contain additional features not shown to increase their resilience and permit the necessary deformation when the lens barrel is inserted into the lens moving mechanism. This structure effectively makes the insertion of the lens barrel into the lens moving mechanism a one-way operation. The lens barrel is thereafter prevented from dropping out of the lens moving mechanism even if the protruding tab  1830  and the corresponding recess  1834  are subsequently aligned. 
       FIG. 19  shows another embodiment of a tab and a corresponding recess. In this embodiment the protruding tab  1930  is chamfered wherein a width of a top surface of the protruding tab is narrower than a bottom surface of the protruding tab such that force is required to insert the protruding tab past the corresponding recess  1934  in the opening of the lens moving mechanism. This embodiment is otherwise like the preceding embodiment. It will be appreciated that both the protruding tab and the corresponding recess may be chamfered and be otherwise like the preceding embodiments. 
       FIG. 20  is a cross-sectional view of the components of another embodiment of a camera module in an unassembled configuration.  FIG. 21  is a cross-sectional view of the camera module of  FIG. 20  in an assembled configuration. In this embodiment a retaining structure  2018  is attached to the lens moving mechanism  2000  after the lens assembly  2010  is received in the lens moving mechanism to reduce a diameter of the opening  2002  on the backside of the lens moving mechanism that receives the lens assembly to be less than a diameter of the second cylindrical portion  2016  of the lens assembly  2010  adjacent the opening. The retaining structure  2018  may be a ring with a circular opening having a smaller diameter than the second cylindrical portion  2016  of the lens assembly  2010  adjacent the opening  2002 . 
       FIG. 22  shows a plan view of a retaining structure  2218  that provides an opening with a non-circular shape, e.g. a rectangular shape, in which some, but not all, diameters of the retaining opening  2220  in the retaining structure are smaller than the diameter of the second cylindrical portion  2216  of the lens assembly adjacent the opening on the backside of the lens moving mechanism that receives the lens assembly. In the figure, the diameters of the retaining opening  2220  that occlude portions of the second cylindrical portion  2216  of the lens assembly as shown by the dashed lines are less than the diameter of the lens assembly and therefore restrain the lens assembly against contact with the image sensor. 
       FIG. 23  is a cross-sectional view of the components of another embodiment of a camera module  2300  in an assembled configuration. In this embodiment a protective structure  2324 ,  2326  is attached to the substrate  2322  at a location where the protective structure prevents the lens assembly  2310  from contacting the image sensor  2320  when not engaged with the lens moving mechanism  2302 . The protective structure  2324 ,  2326  is aligned vertically below the lens barrel wall  2316  and has an upper surface adjacent the backside of the lens moving mechanism  2302  that is higher than the components on the underlying substrate  2322  being protected. Such protective structures could serve either a purely mechanical purpose, or additionally a functional purpose. An example of a functional protective structure would be positioning of one or more capacitors that are mechanically and electrically coupled to the underlying substrate  2322 . A purely mechanical protective structure could consist of a molded or machined structure that is mechanically fastened to the substrate  2322 , such as being glued, or soldered in place. A purely mechanical protective structure could consist of the same bulk material as the substrate. 
     While certain exemplary embodiments have been described and shown in the accompanying drawings, it is to be understood that such embodiments are merely illustrative of and not restrictive on the broad invention, and that this invention is not limited to the specific constructions and arrangements shown and described, since various other modifications may occur to those of ordinary skill in the art. The description is thus to be regarded as illustrative instead of limiting.

Metadata:
Filing Date: 20120928
Publication Date: 20141202
Grant Date: 20141202
Priority Date: 20120608
Inventors: BRODIE DOUGLAS STUART
WEBSTER STEVEN
TAM TERENCE N.
Assignee: APPLE INC
CPC Classifications: [{"code": "G02B13/001", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B13/001", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B7/04", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B7/023", "inventive": true, "first": true, "tree": "[]"}, {"code": "Y10T29/49826", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02B7/023", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02B7/04", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 48539457