Abstract:
A camera module with a lens barrel containing a lens, and a lens carrier that slidably receives the lens barrel. Each of the exterior surface of the lens barrel and the interior surface of the lens carrier include a seating surface formed thereon. One of the exterior surface of the lens barrel and the interior surface of the lens carrier include a plurality of protrusions for controlling the relative position of the lens barrel and the lens carrier. The other of the exterior surface of the lens barrel and the interior surface of the lens carrier include a plurality of channels that are sized and arranged so as to slidably receive the protrusions to allow for the lens barrel to be slid into the lens carrier. The channels also each include a transverse section to allow the lens barrel to be pivoted about an optical axis of the lens barrel.

Description:
CROSS REFERENCE 
     This application is the non-provisional of U.S. Provisional Pat. Appl. No. 61/485,276 filed May 12, 2011, entitled “CAMERA MODULE WITH THREADLESS LENS BARREL ENGAGEMENT DESIGN,” which is hereby incorporated by reference into this application. 
     BACKGROUND 
     The disclosure herein relates generally to electronic devices, and more particularly to digital camera modules. Even more particularly, it relates to a digital camera module design that prevents or minimizes debris and particulate matter produced by the focusing process from contaminating the sensor array of an image capture device. 
     Digital camera modules are currently being incorporated into a variety of electronic devices. Such camera hosting devices include, but are not limited to, cellular telephones, personal data assistants (PDAs), and computers. The demand for digital camera modules continues to grow as the ability to incorporate the camera modules into host devices expands. Therefore, one design goal of digital camera modules is to make them as small as possible so that they will fit into an electronic device without substantially increasing the overall size of the device. Means for achieving this goal must, of course, preserve the quality of the image captured by the camera modules. 
     Such digital camera modules typically include a substrate, an image capture device, a housing, and a lens unit. The substrate is typically a printed circuit board (PCB) that includes circuitry to facilitate data exchange between the image capture device and the host device. The image capture device is mounted and electrically coupled to the circuitry of the PCB. The housing is then mounted on the PCB over the image capture device. The housing includes an opening that receives and centers the lens unit with respect to the image capture device. Typically, the opening includes a set of threads and the lens unit includes a complementary set of threads that facilitate the factory focusing of the camera module. During a factory focus operation, for example, focusing equipment rotates the lens unit with respect to the housing, which adjusts the distance between the lens unit and the image capture device. When the lens unit is properly focused, it is fixed in position with respect to the housing with an adhesive, a thermal weld, or the like. 
     Camera modules that are focused via thread sets have some disadvantages. For example, as the lens unit is rotated within the housing, sliding friction between threads can create particulate debris that could easily contaminate the image sensor and/or other optical components (e.g., infra-red filters, protective covers, other lenses, etc.). Consequently, these contaminants can accumulate and noticeably degrade the quality of captured images by, for example, blocking light to the image sensor. As another example, focusing operations can be difficult and consume a great deal of manufacturing time. As a result, the manufacturing output rate of camera modules that are focused via threads is relatively low. 
     In efforts to minimize the accumulation of such debris, manufacturers currently have to closely control the amount of torque used to rotate the lens unit during factory focusing. However, doing so is tedious and still can cause a significant amount of debris to form. Oftentimes, camera modules have to be discarded as a result of being contaminated. Accordingly, there are relatively high yield losses associated with camera modules that are focused via threads. 
     What is needed, therefore, is a camera module design that is less susceptible to contamination during the assembly and focusing processes. What is also needed is a camera module design that improves manufacturing output and focal accuracy. 
     SUMMARY 
     Disclosed herein is a camera module, that includes a housing; a lens carrier received within the housing, the lens carrier including a seating surface on an interior surface thereof; and a lens barrel containing a lens, the lens barrel including a seating surface on an exterior surface thereof, the lens barrel slidably received within the lens carrier to such point as the seating surface of the lens barrel meets the seating surface of the lens carrier. 
     The lens barrel may include a plurality of protrusions formed on an external surface thereof. The lens carrier may include a plurality of channels formed on an internal surface thereof, the channels each sized and arranged so as to slidably receive one of the protrusions when the lens barrel is slidably received within the lens carrier. Each channel may include a transverse section thereof to allow the lens barrel to be pivoted about an optical axis of the lens barrel once the lens barrel is slidably received within the lens carrier. The protrusions may be equally-spaced apart from each other. There may be three protrusions and they may each be angularly spaced apart from each other by 120 degrees. 
     The lens carrier may have a first cylindrically-shaped interior surface defining an opening having a first diameter and a second cylindrically-shaped interior surface defining an opening having a second diameter, the first diameter being smaller than the second diameter, the seating surface of the lens carrier being an annular surface that connects the first and second cylindrically-shaped interior surfaces. The lens barrel may have a first cylindrically-shaped exterior surface defining an opening having a first diameter and a second cylindrically-shaped exterior surface defining an opening having a second diameter, the first diameter being smaller than the second diameter, the seating surface of the lens barrel being an annular surface that connects the first and second cylindrically-shaped interior surfaces. 
     The camera module may further include an adhesive material affixing the lens carrier to the lens barrel. The camera module may further include a substrate to which the housing is attached; and an image capture device attached to the substrate. 
     Also disclosed is a method of assembling a camera module, the method including providing a lens carrier having a seating surface formed thereon; providing a lens barrel having a seating surface formed thereon; and slidably inserting the lens barrel into the lens carrier until the seating surface of the lens barrel abuts the seating surface of the lens carrier. 
     The method may further include using adhesive to affix the lens barrel to the lens carrier. One of the interior surface of the lens carrier and the exterior surface of the lens barrel may include a plurality of protrusions. The slidably inserting operation may include first aligning a plurality of protrusions on one of the lens carrier and the lens barrel with a plurality of channels on the other of the lens carrier and the lens barrel so that, when the lens barrel is slidably inserted, the protrusions are received within and slide along the channels. The method may further include, after the slidably inserting operation, pivoting the lens barrel about an optical axis associated therewith to move the protrusions into transverse sections of the channels. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosure herein is described with reference to the following drawings, wherein like reference numbers denote substantially similar elements: 
         FIG. 1  is a cross sectional view of a threadless lens barrel engagement assembly  100  according to one embodiment; 
         FIG. 2  is a partially-exploded perspective view of the threadless lens barrel engagement assembly  100  of  FIG. 1 ; 
         FIG. 3  is an exploded perspective view of a lens carrier  104  and a lens barrel  106  of the threadless lens barrel engagement assembly  100  of  FIG. 1 ; 
         FIG. 4  is a perspective view wherein the lens carrier  104  and lens barrel  106  of  FIG. 3  are shown assembled; 
         FIG. 5  is a cross sectional view of a threadless lens barrel engagement assembly  500  according to another embodiment; 
         FIG. 6  is a partially-exploded perspective view of the threadless lens barrel engagement assembly  500  of  FIG. 5 ; 
         FIG. 7  is an exploded perspective view of a lens carrier  504  and a lens barrel  506  of the threadless lens barrel engagement assembly  500  of  FIG. 5 ; and 
         FIG. 8  is a perspective view wherein the lens carrier  504  and lens barrel  506  of  FIG. 7  are shown assembled, with the lens carrier  504  made partially transparent in order to see the lens barrel  506  seated therewithin. 
         FIG. 9  is a sectional view of a camera module. 
         FIG. 10  is a flowchart of a process for assembling a camera module. 
     
    
    
     DETAILED DESCRIPTION 
     While the embodiments disclosed herein are susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that it is not intended to limit the invention to the particular form disclosed, but rather, the invention is to cover all modifications, equivalents, and alternatives of embodiments of the invention as defined by the claims. The disclosure is described with reference to the drawings, wherein like reference numbers denote substantially similar elements. 
       FIG. 1  is a cross sectional view of a threadless lens barrel engagement assembly  100  according to one embodiment. Assembly  100  includes a housing  102 , a lens carrier  104 , and a lens barrel  106 . Lens carrier  104  is positioned within housing  102 , and lens barrel  106  is positioned within lens carrier  104 . Lens barrel  106  is fixably mounted in lens carrier  104  via an epoxy  108  or other suitable means. 
       FIG. 2  is a perspective view of lens barrel  106  exploded from assembly  100  along an optical axis  200 . The interior of lens carrier  104  defines three concave channels  202  (with transverse sections provided for each channel for when the lens barrel  106  is pivoted), and lens barrel  106  defines three complementary convex features  204  that, together, facilitate the positioning of lens barrel  106  with respect to lens carrier  104 . Lens carrier  104  further includes a surface  206  that defines a lip, shoulder, or sitting plane that extends generally perpendicularly with respect to optical axis  200 . Similarly, lens barrel  106  defines a corresponding planar surface  208  that creates a lip or shoulder and extends generally perpendicularly with respect to the optical axis  200 . When lens barrel  106  is received fully within lens carrier  104 , the surfaces  206  and  208  come into contact. 
       FIG. 3  is an exploded perspective view of lens carrier  104  and lens barrel  106 . As shown, lens carrier  104  also includes a coil winding area  300  and three openings  302 . Each of openings  302  is adjacent to and in communication with a respective one of channels  202 . 
     In mounting lens barrel  106  to lens carrier  104 , lens barrel  106  is first coaxially aligned with respect to lens carrier  104  wherein each of features  204  is aligned with a respective one of concave channels  202 . Then, lens barrel  106  is inserted into lens carrier  104  such that features  204  slide in channels  202 . Once lens barrel  106  is seated within lens carrier  104 , lens barrel  106  is rotated clockwise about axis  200  thereby aligning each of features  204  with a respective one of openings  302 . Alignment of features  204  with openings  302  locks the height position of lens barrel  106  with respect to lens carrier  104 . When lens barrel  106  is seated within lens carrier  104 , the planar surfaces  206  and  208  are parallel to one another and perpendicular to optical axis  200 . 
       FIG. 4  is a perspective view of lens barrel  106  seated in lens carrier  104  wherein the height position of lens barrel  106  is locked. For slider release purposes, openings  302  provide access to lens barrel  106  through the side walls of lens carrier  104 . 
     Once lens barrel  106  is properly seated in lens carrier  104 , epoxy  108  is dispensed within a channel  400  defined by the interior walls of lens carrier  104  and the exterior of lens barrel  106 . Once epoxy  108  cures, lens barrel  106  is permanently fixed in lens carrier  104 . Lens carrier  104  can be received with housing  102  before or after lens barrel  106  is received within lens carrier  104 . The lens carrier  104  may be fixed to the housing  102  or may be slidably received therein for auto-focus or zoom operations. Also, the lens carrier  104  could be eliminated and the lens barrel  106  could be attached directly to the housing  102  in the fashion described herein for attachment of the lens barrel  106  to the lens carrier  104 . 
     The three concave channels  202  and the three convex features  204  may be equally spaced apart from each other around the cylindrical shape of the lens carrier  104  and the lens barrel  106 , respectively. For example, they could each be angularly spaced apart by  120  degrees. Other angular spacings could also be used, as could other numbers of channels  202  and features  204 . 
       FIG. 5  is a cross sectional view of a threadless lens barrel engagement assembly  500  according to another embodiment. Assembly  500  includes a housing  502 , a lens carrier  504 , and a lens barrel  506 . Lens carrier  504  is positioned within housing  502 , and lens barrel  506  is positioned within lens carrier  504 . Lens barrel  506  includes three centering dimples or protrusions  508  and is fixably mounted in lens carrier  504  via epoxy  510  or other suitable means. 
       FIG. 6  shows a perspective view of lens barrel  506  exploded from lens carrier  504  and housing  502  along an optical axis  600 . As shown, lens carrier  504  includes a surface  602  that defines a lip, shoulder, or sitting plane that extends generally perpendicularly with respect to optical axis  600 . Similarly, lens barrel  506  defines a planar surface  604  that creates a lip or shoulder and extends generally perpendicularly with respect to optical axis  600 . 
       FIG. 7  shows a perspective view of lens barrel  506  exploded from lens carrier  504 . As shown, lens carrier  504  further includes a coil winding area  700 . In mounting lens barrel  506  to lens carrier  504 , lens barrel  506  is first coaxially aligned with respect to lens carrier  504 . Then, lens barrel  506  is inserted in lens carrier  504  such that surfaces  602  and  604  abut one another and are parallel. When lens barrel  506  is seated in lens carrier  504 , protrusions  508  facilitate the coaxial alignment therebetween. 
       FIG. 8  shows a perspective view of lens barrel  506  seated in lens carrier  504 . With lens barrel  506  being properly seated in lens carrier  504 , epoxy  510  is dispensed within a channel  800  defined by the interior wall(s) of lens carrier  504  and the exterior of lens barrel  506 . Once epoxy  510  cures, lens barrel  506  is permanently fixed in lens carrier  504 . 
       FIG. 9  shows further detail about a camera module  800 . As can be seen, the camera module  800  includes a substrate  802  (e.g., a printed circuit board (which may or may not be flexible) or any other suitable type of substrate) and an image capture device  804  (e.g., a CMOS image sensor or any other suitable type of ICD). The previously-described combination of the housing  502 , the lens carrier  504 , and the lens barrel  506  may be attached by any suitable means. Further, this combination may be attached to the substrate  802 , the ICD  804 , or to both. In this case, it is shown as attached to the substrate  802 . The lens barrel in this example is shown as containing two lens elements  806  and  808 . Although there are two elements shown here, the lens could include any suitable number of lens elements. Further, the lens elements could be of any suitable shape, which could include symmetrical or asymmetrical. Further, although double-convex lens elements are shown here, this is just for ease of illustration. The previously-described lips or shoulders on the lens carrier  504  and lens barrel  506  can be seen well in this figure, and it can be seen in conjunction with the other figures that they are shaped as annular surfaces. They may be more generally referred to as first and second seating surfaces  810  and  812  that positionally register the lens barrel  506  with the lens carrier  504 . They are shown in the figure as not quite in contact with each other, but they may or may not be in contact. 
       FIG. 10  shows a flowchart  900  of the process disclosed herein. A lens carrier is provided ( 902 ) having a seating surface formed thereon. A lens barrel is provided ( 904 ) having a seating surface formed thereon. The lens barrel is slidably inserted ( 906 ) into the lens carrier until the seating surface of the lens barrel abuts the seating surface of the lens carrier. Other subsequent steps not shown that may be employed may include one or both of: pivoting the lens barrel relative to the lens carrier in order to lock the lens barrel in place by causing the protrusions  204 / 508  to slide into transverse sections of the channels  202 ; and adhering the lens barrel to the lens carrier with a suitable adhesive or epoxy. 
     Although the disclosure herein describes the protrusions as being on the exterior surface of the lens barrel and the channels as being on the interior surface of the lens carrier, these positions could be reversed. Further the shape of the channel could be changed to any suitable shape. 
     The disclosed camera module provide several advantages over the prior art. First, there is the elimination of contamination of the image sensor caused by the focusing process of the lens barrel, for example, when complementary thread sets are employed. This, in turn, reduces contamination-related yield losses during production. Furthermore, there is less risk of contamination if the camera module is exposed to non-controlled environment(s) during the assembly process. 
     While the embodiments of the invention have been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered as examples and not restrictive in character. For example, certain embodiments described hereinabove may be combinable with other described embodiments and/or arranged in other ways (e.g., process elements may be performed in other sequences). Accordingly, it should be understood that only example embodiments and variants thereof have been shown and described.