Abstract:
Exemplary system and process for assembling a camera module are provided. The system includes a worktable, a light intensity sensor, a lens module holding device and a controlling unit. The worktable provide placement of the image sensor module thereon, thus a center of the image sensor having a coordinate value thereof. The lens module holding device can hold and move the lens module above the worktable, and it has a light source to emit parallel light that converged at a focus point, wherein the light intensity sensor can detect the focus point location and generating a signal associated with a coordinate value of the focus point. The controlling unit can receive the signal and instruct the lens module holding device to move the lens module toward the image sensor module so that the optical axis of the lens module is aligned with the center of the image sensor.

Description:
BACKGROUND 
     1. Technical Field 
     The present invention relates generally to system and process for assembling camera modules. 
     2. Description of Related Art 
     Nowadays, digital camera modules are widely accepted for their ease of use, digital image storage, immediate results and image management potential. With respect to a related camera module, they generally include a lens module, a base member, and an image sensor fixed on the base member. The image sensor and the base member are located at an image side of the lens module. The image sensor is configured for detecting optical signals representative of a target image and converting the optical signals into electronic signals. The image sensor usually is a charge coupled device (CCD) or a complementary metal-oxide semiconductor (CMOS) device. The lens module generally includes a lens barrel, a lens holder, at least a lens group, a spacer, and a filter (e.g., IR-cut filter). The lens group, the spacer and the filter are received in and arranged along an optical axis of the lens barrel. The lens holder defines an opening therein. An internal thread is defined on peripheral sidewalls of the opening. The internal thread is engaged together with an external thread of the lens barrel for thereby holding the lens barrel. 
     During the manufacture of the camera module, the at least one lens group, the filter, etc. are placed into the lens barrel and thereafter the lens barrel is threadedly coupled to the lens holder so as to form the lens module. Then, the lens module is mounted on the base member, thereby completing camera module assembly. Generally, before the lens module is mounted on the based member, there is a requirement for a center of the image sensor to be aligned with an optical axis of the lens module. A conventional method for meeting the above requirement is that of aligning the center of the image sensor with a center line of the lens barrel or a center line of an aperture opening of the lens barrel, based on an assumption that the center line of the lens barrel or the center line of the aperture opening is identical to an optical axis of the lens module. However, deviation between the optical axis of the lens module and the centerline of the lens barrel (or the center line of the aperture opening) inevitably exists, which results in an image quality of the camera module being degraded to some extent. 
     What is needed, therefore, is to provide system and process for assembling camera modules, thereby an optical axis of a lens module of an assembled camera module would be exactly aligned with a center of an image sensor of the assembled camera module. 
     SUMMARY 
     A first preferred embodiment provides a system for assembling a camera module, the camera module having a lens module and an image sensor module, the lens module having an optical axis associated therewith, the image sensor module including a base and an image sensor mounted on the base. The system includes a worktable with a coordinate system defined thereon, a light intensity sensor arranged on the worktable, a lens module holding device and a controlling unit. The worktable is configured (i.e., structured and arranged) for allowing placement of the image sensor module thereon, thus a center of the image sensor of the image sensor module has a coordinate value. The lens module holding device is configured for holding and moving the lens module in a manner such that the lens module is arranged above the light intensity sensor and the optical axis associated with the lens module is perpendicular to a main plane of the worktable. The lens module holding device has a parallel light source configured for emitting parallel lights toward the lens module. The parallel lights are parallel to the optical axis of the lens module and converge at a focus point on the light intensity sensor. The light intensity sensor is configured for detecting the focus point location and generating a signal associated with a coordinate value of the focus point. The controlling unit is configured for receiving the signal from the light intensity sensor and controlling movement of the lens module holding device and the lens module toward the image sensor module in a manner such that the optical axis of the lens module is aligned with the center of the image sensor based upon a coordinate relationship between the coordinate values of the focus point and the center of the image sensor. 
     A second preferred embodiment provides a process for assembling a camera module using the assembling system described above. The process comprises placing an image sensor module on a worktable, the image sensor module including a base and an image sensor mounted on the base, the worktable having a coordinate system defined thereon. A center of the image sensor of the image sensor module has coordinate values defined thereon. A light intensity sensor should be arranged on the worktable. A lens module having an optical axis associate therewith is also provided. The lens module is moved in a manner such that the lens module is arranged above the light intensity sensor with the optical axis associated with the lens module perpendicular to a main plane of the worktable. A plurality of parallel lights can be projected toward the lens module, the lights being parallel to the optical axis of the lens module, in a manner such that the lights converge at a focus point on the light intensity sensor. The focus point location should be detected and a signal associated with a coordinate value of the focus point then generated using the light intensity sensor. The signal can be received by the controlling unit. The lens module holding device can be made to move the lens module toward the image sensor module such that the optical axis of the lens module is aligned with the center of the image sensor based upon a coordinate relationship between the coordinate values of the focus point and the center of the image sensor. 
     Other advantages and novel features will become more apparent from the following detailed description of preferred embodiments when taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Many aspects of the present system and process for assembling a camera module can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present system and process for assembling for a camera module. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views. 
         FIG. 1  is a schematic, isometric view of a system for assembling a camera module according to a first preferred embodiment, showing the system including a lens module holding device; 
         FIG. 2  is a schematic, cross-sectional views of the lens module holding device of the system in  FIG. 1 , taking along line II-II; 
         FIG. 3  shows a stage of process for assembling a camera module using the system of  FIG. 1 , for obtaining an image center of a lens module; 
         FIG. 4  is a schematic, cross-sectional views of the system and the lens module in  FIG. 3 , taking along line IV-IV; and 
         FIG. 5  is a subsequent stage of the process of  FIG. 3 , for engaging the lens module with an image sensor. 
     
    
    
     The exemplifications set out herein illustrate various preferred embodiments, in various forms, and such exemplifications are not to be construed as limiting the scope of the present system and process for assembling camera module in any manner. 
     DETAILED DESCRIPTION 
     Referring to  FIGS. 1 through 3 , a system  10  for assembling a camera module, in accordance with a first preferred embodiment, is provided. The camera module includes a lens module  110  and an image sensor module  100 . The lens module  110  has an optical axis associated therewith and the image sensor module  100  includes a base member  101  and an image sensor  102  mounted on the base member  101 . The present system  10  includes a worktable  11 , a light intensity sensor  12 , a lens module holding device  13 , and a controlling unit  14 . 
     The worktable  11  with a coordinate system defined thereon is configured for predetermined placement of the image sensor module  100  thereon, thus a center of the image sensor  102  of the image sensor module  100  has initial coordinate values (X 2 , Y 2 ). 
     The light intensity sensor  12  is arranged on the worktable  11  and includes a number of sensing areas. Each of the sensing areas includes at least a pixel and can generate a signal after being irradiated by a light beam of a certain light intensity. 
     The lens module holding device  13  is movably located above the worktable  11  and configured for holding and moving the lens module  110  in a manner such that the lens module  110  is arranged above the light intensity sensor  12  and the optical axis associated with the lens module  110  is perpendicular to a main plane of the worktable  11 . The lens module holding device  13  includes a parallel light source  131  and a suction opening  132  opposite to the parallel light source  131 . The parallel light source  131  is configured for emitting parallel light (as indicated by the arrows in  FIG. 2 ) toward the lens module  110 . When the suction opening  132  captures the lens module by a suction force, the suction opening  132  contacts with the lens module  110  and the parallel light is vertically incident into the lens module  110  after passing through the suction opening  132 . In the illustrated embodiment, the lens module holding device  13  further includes a vacuum chamber  133  having an adjustable inner pressure. The suction opening  132  is in communication with the vacuum chamber  133 . The parallel light source  131  is disposed in the vacuum chamber  133  and opposite to the suction opening  132 , thus allowing light emitted from the parallel light source  131  to pass through the suction opening  132 . The vacuum chamber  133  generally is in communication with a vacuum pump via an opening  134  (as shown in  FIG. 2 ) defined therein allowing the inner pressure to be adjustable. 
     The controlling unit  14  is electrically connected to the light intensity sensor  12  and the lens module holding device  13 . Information representative of coordinate values of the center of image sensor  102  on the worktable  11  is recorded in the controlling unit  14 . The controlling unit  14  is configured (i.e., structured and arranged) for receiving the signal from the light intensity sensor  12  so as to obtain coordinate values (X 1 , Y 1 ) of the sensing area irradiated by a light beam. The controlling unit  14  then compares the signal with the recorded information representative of the coordinate values (X 2 , Y 2 ) of the center of image sensor  102  to obtain a coordinate relationship between the coordinate values (X 1 , Y 1 ) of the sensing area and the initial coordinate values (X 2 , Y 2 ) of the center of image sensor  102 . A control signal based upon the coordinate relationship is generated, and outputted into the lens module holding device  13  to instruct it. Thereafter, the lens module holding device  13  can move the lens module  110  toward the image sensor module  100  in a manner such that the optical axis of the lens module  110  is aligned with the center of the image sensor  102  and then engaged with the base member  101 . 
     In the illustrated embodiment, the parallel light emitted from the parallel light source  131  is emitted in a direction parallel to the optical axis of the lens module  110  vertically incident on the lens module  110  and converges at a focus point  106  on the light intensity sensor  12 , after passing through the lens module  110 . It is noted that, the focus point  106  corresponds to an image center of the lens module  110  that coincides with the optical axis thereof. In other words, if the image center of the lens module  110  is moved to the center of the image sensor  102 , as a result that the optical axis of the lens module  110  will aligned with the center of the image sensor  102 . 
     Referring to  FIGS. 3 through 5 , a process for assembling a camera module using the system  10 , in accordance with a second preferred embodiment, is provided. Generally, the lens module  110  includes a lens barrel  103 , at least one lens group  105  received in the lens barrel  103 , and a lens holder  104  threadedly coupled with the lens barrel  103 . The process for assembling a camera module includes a series of steps. 
     In particular, an image sensor  100  is placed in a predetermined position of the worktable  11 , and the center of image sensor  102  has coordinate values (X 2 , Y 2 ) defined thereon. A light intensity sensor  12  should be arranged on the worktable  11 . A lens module  110  that having an optical axis associate therewith is provided. The lens module  110  is held and moved in a manner such that the lens module  110  is arranged above the light intensity sensor  12  with the optical axis associated with the lens module  110  is oriented perpendicular to a main plane of the worktable  11  by means of the suction opening  132  of the lens module holding device  13 . The parallel light is vertically projected toward at least one lens group  105  of the lens barrel  103 . The parallel light converge at a focus point  106  on at least one sensing area of the light intensity sensor  12 . The focus point  106  location is detected and a signal associated with coordinate values (X 1 , Y 1 ) of the focus point  106  then generated using the light intensity sensor  12 . The signal is then transmitted to the controlling unit  14 . The lens module holding device  13  moves the lens module  110  toward the image sensor module  100  according to the received signal representative of the coordinate values (X 1 , Y 1 ) of the focus point  106 , such that the optical axis of the lens module  110  is aligned with the center of the image sensor  102  based upon a coordinate relationship between the coordinate values (X 1 , Y 1 ) and the coordinate values (X 2 , Y 2 ). Thereafter, the lens module  110  is moved to just above the image sensor  102  and aligns the optical axis of the lens module  110  with the center of the image sensor  102 . After the optical axis of the lens module  110  is aligned with the center of the image sensor  102 , the lens holder  104  will be engaged with the base member  101  by means of the lens module holding device  13  moving close to the worktable  11 , as shown in  FIG. 5 . 
     Advantageously, many methods can be used to engage the lens holder  104  with the base member  101 , such as cementing method, locked method etc. Preferably, a step of coating adhesive onto the base member  101  before the step of moving the lens module to right above the light intensity sensor  12  or after the step of moving the lens module to align the center of the image sensor  102  with an optical axis thereof and before the step of moving the lens module to engage with the base member  101 . 
     Furthermore it can be understood that a number of base member  101  on which the image sensor  102  is assembled, are placed at predetermined positions on the worktable  11 , and information representative of coordinate values of the center of image sensors  102  on the worktable  11  are recorded in the controlling unit  14 . The controlling unit  14  receives the signal representative of coordinate values of the sensing area irradiated by light beam generated by the light intensity sensor  12 . The controlling unit  14  then compares the signal with the recorded information so as to obtain a coordinate relationship between the coordinate values of the sensing area and the coordinate values of the center of image sensor corresponding to the information compared. The controlling unit  14  generates a control signal based upon the coordinate relationship and outputs the control signal into the lens module holding device  13 . Thereafter, the lens module  110  could be moved to align the optical axis thereof with the center of image sensor  102  and then engaged with the base member  101 , via the lens module holding device  13  under the control of the control signal. Thereby, the next lens module  110  could be held in engagement with the base member  101  by means of the lens module holding device  13  aligning the optical axis of the lens module with the center of the image sensor after a camera module has been assembled. This result in an improved assembly efficiency of the assembling processes for camera modules. 
     It is to be understood, however, that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.