PATENT DOCUMENT

Publication Number: US-9077878-B2
Application Number: US-201213631574-A
Country: US
Kind Code: B2

Title: Alternative lens insertion methods and associated features for camera modules

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 engages the second cylindrical portion to rotate the lens assembly and engage the externally threaded portion of the lens assembly with an internally threaded portion of a movable sleeve in the lens moving mechanism.

Claims:
What is claimed is: 
     
       1. A method of assembling a camera module, the method comprising:
 inserting a lens assembly into a lens moving mechanism, the lens assembly including 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; 
 engaging an installation tool with the second cylindrical portion of the lens assembly, a portion of the installation tool that engages the lens assembly having a diameter no greater than the diameter of the second cylindrical portion of the lens assembly; 
 rotating the lens assembly with the installation tool to engage the externally threaded portion of the lens assembly with an internally threaded portion of a movable sleeve in the lens moving mechanism; and 
 coupling an image sensor to the lens moving mechanism such that the second cylindrical portion of the lens assembly is closest to the image sensor. 
 
     
     
       2. The method 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 method of  claim 1  wherein the lens moving mechanism is a voice coil motor. 
     
     
       4. The method of  claim 1  further comprising applying a vacuum to hold the lens assembly with the installation tool. 
     
     
       5. The method of  claim 1  wherein the installation tool mechanically engages the second cylindrical portion of the lens assembly. 
     
     
       6. The method of  claim 1  wherein a surface of the installation tool that engages the second cylindrical portion of the lens assembly is a material having a coefficient of static friction greater than 0.6. 
     
     
       7. The method of  claim 1  wherein engaging the installation tool further comprises using a temporary adhesive to join the lens barrel to the installation tool. 
     
     
       8. The method of  claim 7  further comprising separating the lens barrel from the installation tool at the adhesive joint. 
     
     
       9. The method of  claim 1  wherein the installation tool engages an inside surface of the second cylindrical portion of the lens assembly. 
     
     
       10. The method of  claim 9  wherein the inside surface of the second cylindrical portion of the lens assembly provides a conical recess and the installation tool provides a conical surface that presses against the conical recess. 
     
     
       11. The method of  claim 10  wherein the conical surface of the installation tool is a material having a coefficient of static friction greater than 0.6. 
     
     
       12. The method of  claim 9  wherein the inside surface of the second cylindrical portion of the lens assembly provides a cylindrical recess with a surface parallel to an optical axis of the lens assembly and the installation tool provides a gripping section that expands to press against the cylindrical recess. 
     
     
       13. The method of  claim 12  wherein the gripping section of the installation tool is mechanically expanded to press against the cylindrical recess. 
     
     
       14. The method of  claim 12  wherein the gripping section of the installation tool is pneumatically expanded to press against the cylindrical recess. 
     
     
       15. The method of  claim 12  wherein the gripping section of the installation tool is hydraulically expanded to press against the cylindrical recess. 
     
     
       16. The method of  claim 12  wherein the gripping section of the installation tool includes a material having a coefficient of static friction greater than 0.6. 
     
     
       17. The method of  claim 12  further comprising applying a vacuum to hold the lens assembly with the installation tool, the vacuum causing the lens assembly to press against the gripping section of the installation tool and cause the gripping section to expand and press against the cylindrical recess. 
     
     
       18. A method of assembling a lens assembly and a lens moving mechanism, the method comprising:
 inserting the lens assembly into the lens moving mechanism, the lens assembly including a lens barrel having a first cylindrical portion that includes an externally threaded portion, a first lens mounted in the first cylindrical portion, a second cylindrical portion that has a larger diameter than the externally threaded portion, and a second lens mounted in the second cylindrical portion, the second lens being the lens that will be closest to an image sensor; 
 engaging an installation tool with the second cylindrical portion of the lens assembly, a portion of the installation tool that engages the lens assembly having a diameter no greater than the diameter of the second cylindrical portion of the lens assembly; and 
 rotating the lens assembly with the installation tool to engage the externally threaded portion of the lens assembly with an internally threaded portion of a movable sleeve in the lens moving mechanism. 
 
     
     
       19. The method of  claim 18  wherein the lens moving mechanism is a voice coil motor. 
     
     
       20. The method of  claim 18  further comprising applying a vacuum to hold the lens assembly with the installation tool. 
     
     
       21. The method of  claim 18  wherein the installation tool mechanically engages the second cylindrical portion of the lens assembly. 
     
     
       22. The method of  claim 18  wherein a surface of the installation tool that engages the second cylindrical portion of the lens assembly is a material having a coefficient of static friction greater than 0.6. 
     
     
       23. The method of  claim 18  wherein engaging the installation tool further comprises using a temporary adhesive to join the lens barrel to the installation tool. 
     
     
       24. The method of  claim 23  further comprising separating the lens barrel from the installation tool at the adhesive joint. 
     
     
       25. The method of  claim 18  wherein the installation tool engages an inside surface of the second cylindrical portion of the lens assembly. 
     
     
       26. The method of  claim 25  wherein the inside surface of the second cylindrical portion of the lens assembly provides a conical recess and the installation tool provides a conical surface that presses against the conical recess. 
     
     
       27. The method of  claim 26  wherein the conical surface of the installation tool is a material having a coefficient of static friction greater than 0.6. 
     
     
       28. The method of  claim 25  wherein the inside surface of the second cylindrical portion of the lens assembly provides a cylindrical recess with a surface parallel to an optical axis of the lens assembly and the installation tool provides a gripping section that expands to press against the cylindrical recess. 
     
     
       29. The method of  claim 28  wherein the gripping section of the installation tool is mechanically expanded to press against the cylindrical recess. 
     
     
       30. The method of  claim 28  wherein the gripping section of the installation tool is pneumatically expanded to press against the cylindrical recess. 
     
     
       31. The method of  claim 28  wherein the gripping section of the installation tool is hydraulically expanded to press against the cylindrical recess. 
     
     
       32. The method of  claim 28  wherein the gripping section of the installation tool includes a material having a coefficient of static friction greater than 0.6. 
     
     
       33. The method of  claim 28  further comprising applying a vacuum to hold the lens assembly with the installation tool, the vacuum causing the lens assembly to press against the gripping section of the installation tool and cause the gripping section to expand and press against the cylindrical recess.

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. 61/625,084, filed Apr. 17, 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. 
     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). 
     Typically a lens is inserted into a lens moving mechanism, such as a voice coil motor, 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. 
     It would be desirable to provide lens insertion methods and structures that allow the camera lens module to be reduced in size. 
    
    
     
       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. 
     
    
    
     DETAILED DESCRIPTION 
     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. 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 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 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 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  800 . 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  800 . 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  1012  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. 
     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: 20150707
Grant Date: 20150707
Priority Date: 20120417
Inventors: BRODIE DOUGLAS STUART
TAM TERENCE N.
Assignee: APPLE INC
CPC Classifications: [{"code": "H04N23/57", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04N23/57", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04N23/55", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04N23/55", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04N5/2254", "inventive": true, "first": true, "tree": "[]"}, {"code": "Y10T29/49826", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04N5/2257", "inventive": true, "first": false, "tree": "[]"}, {"code": "Y10T29/49812", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y10T29/49812", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y10T29/49826", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y10T29/49826", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y10T29/49812", "inventive": false, "first": false, "tree": "[]"}]
Family ID: 49324742