Abstract:
A camera module includes a lens module, an image sensor, a circuit board for supporting the image sensor, and a lens holder for connecting the lens module and the circuit board. A method for fabricating the camera module includes the following steps. Firstly, at least one cleaning hole is created in the lens holder, and the at least one cleaning hole is filled with a removable sealing stuff. Then, the printed circuit board, the image sensor, the lens holder and the lens module of the camera module are combined together. Then, a testing procedure is performed to detect whether any pollutant is present within the assembled camera module. Once any pollutant within the assembled camera module is detected, the sealing stuff is removed from the at least one cleaning hole, a cleaning procedure is done to remove the pollutant, and the at least one cleaning hole is sealed again.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to a camera module, a fabricating method of the camera module, and a cleaning method of the camera module, and more particularly to a camera module, a fabricating method of the camera module, and a cleaning method of the camera module in order for reducing the damage rate, reducing the fabricating cost and increasing the throughput. 
       BACKGROUND OF THE INVENTION 
       [0002]    Nowadays, personal communication devices have experienced great growth and are now rapidly gaining in popularity. The personal communication devices having image capturing devices are gradually marketable. The common image capturing devices are for example camera modules or video camera modules. When the image capturing devices are used in mobile phones, personal digital assistant (PDA) or notebook computers for video recording, video calling, video conferencing or other network applications, the convenience and the diversity of these image capturing devices are evident. Generally, such an image capturing device principally comprises a lens module, a lens holder, an image sensor and a printed circuit board (PCB). An example of the image sensor includes a CCD (charge coupled device) chip or a CMOS (complementary metal-oxide semiconductor) chip. 
         [0003]    Conventionally, there are several methods of assembling the camera module. In accordance with a first assembling method, the image sensor is firstly fixed on the printed circuit board, a filter and a lens module are then combined with a lens holder, and the lens holder is finally glued on the printed circuit board. As such, a close space is defined by the printed circuit board, the lens holder and the filter. During the process of producing, transporting or assembling the camera module, some particles, dust or dirt (also referred as pollutant in this specification) may be brought into the lens module or the image sensor. Under this circumstance, the image quality of the image-capturing device is deteriorated. Generally, a testing process is performed to detect whether there is any pollutant present within the close space. Once any particle, dust or dirt is detected, the lens module needs to be detached from the printed circuit board in order to remove the particle, dust or dirt. Since the lens module has been fixed on the printed circuit board, the process of detaching the lens module from the printed circuit board may easily result in damage of lens module and even cause considerable economic loss. A related discussion is described in for example Taiwanese Utility Model Patent No. 283188, entitled “Assembling structure of lens module”. If there is a stain on the image sensor after the lens module has been glued on the printed circuit board, the lens module needs to be detached from the printed circuit board. This may leads to damage of the lens module and thus the lens module may fail to be used again. Under this circumstance, the manufacturing cost is increased. Therefore, there is a need of providing an improved fabricating method of the camera module. 
         [0004]    In accordance with a second assembling method, the configurations of the camera module are similar to those made by the first assembling method. The lens module has a lens set and a lens barrel sheltering the lens set. After the camera module is assembled, the lens barrel of the lens module could be twisted out in order to perform a cleaning procedure. Although the cleaning procedure is simplified in comparison with the first assembling method, there are still some drawbacks. For example, after the cleaning procedure is completed, the lens barrel needs to be twisted in the lens holder again in order to recombine the lens barrel and the lens holder. During the lens barrel is twisted in the lens holder, particles are readily generated due to friction between the thread structures of the lens barrel and the lens holder. Once the particles fall into the internal portion of the camera module, a secondary pollution problem occurs and the image quality is also adversely affected. Under this circumstance, the yield of the camera module is still unsatisfactory. 
       SUMMARY OF THE INVENTION 
       [0005]    In accordance with an aspect of the present invention, there is provided a method for fabricating a camera module. The camera module includes a lens module, an image sensor, a printed circuit board for supporting the image sensor, and a lens holder for connecting the lens module and the printed circuit board. The method for fabricating a camera module includes the following steps. Firstly, at least one cleaning hole is created in the lens holder, and the at least one cleaning hole is filled with a removable sealing stuff. Then, the printed circuit board, the image sensor, the lens holder and the lens module of the camera module are combined together. Then, a testing procedure is performed to detect whether any pollutant is present within the assembled camera module. Once any pollutant within the assembled camera module is detected, the sealing stuff is removed from the at least one cleaning hole, a cleaning procedure is done to remove the pollutant, and the at least one cleaning hole is closed again. 
         [0006]    In an embodiment, the cleaning procedure includes a step of sucking up the pollutant through the at least one cleaning hole. The step of sucking up the pollutant through the at least one cleaning hole includes sub-steps of: inserting a tubular cleaning tool into an internal portion of the camera module through the at least one cleaning hole, and sucking up the pollutant through the at least one cleaning hole with the tubular cleaning tool. An exemplary tubular cleaning tool is a syringe needle. 
         [0007]    In an embodiment, the cleaning procedure includes a step of blowing off the pollutant through the at least one cleaning hole. The step of blowing off the pollutant through the at least one cleaning hole includes sub-steps of: inserting a tubular cleaning tool into an internal portion of the camera module through the at least one cleaning hole, and blowing off the pollutant through the at least one cleaning hole with the tubular cleaning tool. An exemplary tubular cleaning tool is a syringe needle. 
         [0008]    In a case that the cleaning procedure includes a step of blowing off the pollutant through the at least one cleaning hole, an inner surface of the lens holder is previously coated with a layer of viscous substance on before the camera module is assembled, wherein the pollutant that is blown off is adsorbed on the viscous substance. 
         [0009]    In an embodiment, the cleaning procedure includes steps of: inserting a cleaning tool into an internal portion of the camera module through the at least one cleaning hole, and adsorbing the pollutant with a tip of the cleaning tool so as to remove the pollutant. 
         [0010]    The procedure of removing the sealing stuff is variable according to the selected material of the sealing stuff. In an embodiment, the sealing stuff is removed by pulling or tearing off the sealing stuff from the at least one cleaning hole. In another embodiment, the sealing stuff is an adhesive, and the sealing stuff is removed by dissolving the adhesive with a solvent. 
         [0011]    In accordance with another aspect of the present invention, there is provided a camera module. The camera module includes a printed circuit board, an image sensor, a lens module and a lens holder. The image sensor is mounted on the printed circuit board. By the lens holder, the lens module is fixed on the printed circuit board. The lens holder includes at least one cleaning hole in a sidewall thereof. The at least one cleaning hole is filled with a removable sealing stuff. The sealing stuff is removed from the at least one cleaning hole before a cleaning procedure is done to clean the camera module. 
         [0012]    In an embodiment, the sealing stuff is made of a material that is detachable from the lens holder by a pulling or tearing action. 
         [0013]    In an embodiment, the sealing stuff is soluble in a solvent. 
         [0014]    In an embodiment, an inner surface of the lens holder is coated with a layer of viscous substance. 
         [0015]    In an embodiment, the lens holder is substantially a sleeve with a first opening at a first end and a second opening at a second end, and the first end having the first opening is attached on the printed circuit board. An inner thread structure is formed on an inner surface of the second opening of the lens holder. An outer surface of the lens module has an outer thread structure mating with the inner thread structure, so that the lens module is permitted to be twisted in or twisted out with respect to the lens holder. 
         [0016]    In an embodiment, the second opening is sealed by a transparent sheet-like element, so that the image sensor is accommodated within a close space defined by the printed circuit board, the lens holder and the transparent sheet-like element. 
         [0017]    In an embodiment, the camera module includes an actuator between the lens module and the lens holder for driving the lens module to adjust the focus. 
         [0018]    In accordance with a further aspect of the present invention, there is provided a method for cleaning a camera module. The cleaning method can be carried out during the process of assembling and testing the camera module. In a case that the camera module is returned to the depot service for repair or maintenance, the cleaning method is also feasible. 
         [0019]    The above objects and advantages of the present invention will become more readily apparent to those ordinarily skilled in the art after reviewing the following detailed description and accompanying drawings, in which: 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]      FIG. 1  is a schematic exploded view illustrating a camera module according to an embodiment of the present invention; 
           [0021]      FIG. 2  is a schematic cross-sectional view illustrating the assembly of the camera module shown in  FIG. 1 ; 
           [0022]      FIG. 3  is a schematic exploded view illustrating a camera module according to another embodiment of the present invention; 
           [0023]      FIG. 4  is a schematic cross-sectional view illustrating the assembly of the camera module shown in  FIG. 3 ; 
           [0024]      FIG. 5  is a schematic view illustrating a device for cleaning the camera module shown in  FIG. 1 ; 
           [0025]      FIG. 6  is a schematic view illustrating a device for cleaning the camera module shown in  FIG. 3 ; 
           [0026]      FIG. 7A  is a schematic view illustrating an exemplary cleaning tool used for cleaning the camera module of the present invention; and 
           [0027]      FIG. 7B  is a schematic view illustrating another exemplary cleaning tool used for cleaning the camera module of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0028]      FIG. 1  is a schematic exploded view illustrating a camera module according to an embodiment of the present invention.  FIG. 2  is a schematic cross-sectional view illustrating the assembly of the camera module shown in  FIG. 1 . Please refer to  FIG. 1  and  FIG. 2 . The camera module  1  comprises a lens module  11 , an image sensor  12 , a printed circuit board  13  and a lens holder  14 . The image sensor  12  is mounted on the printed circuit board  13 . The lens module  11  comprises a lens set (not shown) and an external lens barrel  110 . The lens module  11  is fixed on the printed circuit board  13  through the lens holder  14 . As such, an external light can be imaged on the image sensor  12  through the lens module  11  so as to achieve an image capturing function. The camera module  1  is applied to a portable electronic device such as a mobile phone or a personal digital assistant (PDA) or a notebook computer. 
         [0029]    The lens holder  14  is substantially a sleeve with a first opening  141  at a first end and a second opening  142  at a second end. The first end having the first opening  141  is adhered on the printed circuit board  13 . At the second end of the lens holder  14 , an inner thread structure  145  formed on the inner surface of the second opening  142 . The lens barrel  110  of the lens module  11  has an outer thread structure  115  formed on the outer surface thereof. 
         [0030]    The outer thread structure  115  of the lens barrel  110  mates with the inner thread structure  145  of the lens holder  14  such that the lens module  11  can be twisted in or twisted out with respect to the lens holder  14  upon rotation of the lens module  11 . Moreover, a cleaning hole  15  is formed in a sidewall  140  of the lens holder  14 . The cleaning hole  15  is filled with a removable sealing stuff  16 . The sealing stuff  16  is made of an adhesive or similar material that is breakable by a pulling or tearing action or soluble in a specified solvent. The procedure of removing the sealing stuff  16  is variable according to the selected material of the sealing stuff  16 . The location, shape and size of the cleaning hole  15  can be varied according to the size of the camera module  1 , the relative positions of respective components after being assembled, and the size and shape of the cleaning tool. If necessary, the number of the cleaning hole  15  could be increased. For reducing the possibility of causing pollution, it is preferred that the lens holder  14  has at most two cleaning holes  15 . 
         [0031]      FIG. 5  is a schematic view illustrating a device for cleaning the camera module shown in  FIG. 1 . For cleaning the internal portion of the camera module  1 , the sealing stuff  16  needs to be removed from the cleaning hole  15 . Next, a cleaning tool  31  is inserted into the internal portion of the camera module  1  for performing a cleaning procedure. After the pollutant within the internal portion of the camera module  1  is removed, the cleaning hole  15  is filled with the sealing stuff  16  again. Since it is not necessary to separate the lens module  11  from the lens holder  14  by this cleaning method, the secondary pollution problem resulted from recombination of the lens module  11  and the lens holder  14  will be avoided. For removing the pollutant included within the internal portion of the camera module  1 , dry ice or compressed air may be introduced into the internal portion of the camera module  1  with the cleaning tool  31  to blow off the pollutant. Alternatively, the pollutant included within the internal portion of the camera module  1  may be vacuum sucked through the cleaning tool  31 . Alternatively, the pollutant included within the internal portion of the camera module  1  may be removed by an adsorbing or absorbing means. The type of cleaning tool  31  is selected according to the desired means of removing the pollutant. For blowing off or sucking up the pollutant, a syringe needle  33  as shown in  FIG. 7A  is feasible as the cleaning tool  31 . For directly adsorbing the pollutant, the syringe needle  33  as shown in  FIG. 7A  and the stick-like tool  34  as shown in  FIG. 7B  are feasible as the cleaning tool  31 . Since the pollutant could be directly adsorbed on the tip  341  of the stick-like tool  34 , the pollutant is removed after the stick-like tool  34  is ejected out of the camera module  1 . For enhancing the adsorbing efficacy, the tip  341  of the stick-like tool  34  could be previously stained with an adhesive or the tip  341  of the stick-like tool  34  could be made of a highly viscous material. 
         [0032]    Please refer to  FIG. 2 . As known, if the pollutant is present in the imaging region of the image sensor  12 , the imaging quality of the camera module is deteriorated. During the process of blowing off the pollutant, the inner surface  149  of the lens holder  14  could be previously coated with a layer of viscous substance  17 . When the pollutant is blown up by the gas introduced from the cleaning tool, the pollutant will be adherent onto the inner surface  149  of the lens holder  14  in order to preventing the pollutant from returning back the imaging region of the image sensor  12  again. 
         [0033]    For facilitating the fabrication of the camera module  1 , before the camera module  1  is assembled, the cleaning hole  15  is created in the lens holder  14 , the cleaning hole  15  is filled with the sealing stuff  16 , and the inner surface  149  of the lens holder  14  is coated with a layer of viscous substance  17 . During the process of assembling the camera module  1 , the image sensor  12  is mounted on the printed circuit board  13 , then the lens holder  14  is fixed on the printed circuit board  13 , and finally the lens module  11  is combined with the lens holder  14 . After the camera module  1  is assembled, a testing procedure is performed to detect whether any pollutant is present within the assembled camera module  1 . For performing the testing procedure, the electrical contacts (not shown) on the periphery of the image sensor  12  should be electrically connected with a display device (not shown). Via the display device, it can be observed and determined whether there is any pollutant (e.g. particle, dust or dirt) adversely influencing the image quality according to the captured image. Once any pollutant is detected, the sealing stuff  16  is removed from the cleaning hole  15 , such that the cleaning procedure can be performed through the cleaning hole  15 . After the cleaning procedure is completed, the cleaning hole  15  is filled with the sealing stuff  16  again, and the testing procedure is performed again. The cleaning procedure and the testing procedure could be repeatedly implemented until the tester assures that pollutant (e.g. particle, dust or dirt) adversely influencing the image quality is no longer present within the camera module  1 . 
         [0034]      FIG. 3  is a schematic exploded view illustrating a camera module according to another embodiment of the present invention.  FIG. 4  is a schematic cross-sectional view illustrating the assembly of the camera module shown in  FIG. 3 . Please refer to  FIG. 3  and  FIG. 4 . The camera module  2  comprises a lens module  21 , an image sensor  22 , a printed circuit board  23 , a lens holder  24 , and an actuator  29 . The image sensor  22  is mounted on the printed circuit board  23 . The lens holder  24  is substantially a sleeve with a first opening  241  at a first end and a second opening  242  at a second end. The first end having the first opening  241  is adhered on the printed circuit board  23 . The second opening  242  is sealed by a transparent sheet-like element  28 . The transparent sheet-like element  28  is simply a transparent plate for offering a protective efficacy or a light filter having a specified color-filtering efficacy (e.g. an IR light filter). 
         [0035]    The lens holder  24  is fixed on the printed circuit board  23  and encloses the image sensor  22 . As a consequence, a close space is defined by the printed circuit board  23 , the lens holder  24  and the transparent sheet-like element  28 . Similarly, the actuator  29  is substantially a sleeve with a first opening  291  at a first end and a second opening  292  at a second end. The first end having the first opening  291  is attached on the second end of the lens holder  24 . At the second end of the actuator  29 , an inner thread structure  295  formed on the inner surface of the second opening  292 . The lens barrel  210  of the lens module  21  has an outer thread structure  215  formed on the outer surface thereof. The outer thread structure  215  of the lens barrel  210  mates with the inner thread structure  245  of the lens holder  24  such that the lens module  21  can be twisted in or twisted out with respect to the lens holder  24  upon rotation of the lens module  21 . 
         [0036]    The lens module  21  comprises a lens set (not shown) and the external lens barrel  210 . By means of the actuator  29 , the lens module  21  is driven to adjust the focus on a subject. As such, an external light can be imaged on the image sensor  22  through the lens module  21  so as to achieve an image capturing function. The camera module  2  is applied to a portable electronic device such as a mobile phone or a personal digital assistant (PDA) or a notebook computer. 
         [0037]    Since the image sensor  22  is accommodated with the close space defined by the printed circuit board  23 , the lens holder  24  and the transparent sheet-like element  28 , the cleaning procedure fails to be done even if the lens module  11  is disassembled. If the conventional cleaning procedure is employed, the lens holder needs to be detached from the printed circuit board  23 , which leads to damage of the actuator  29  and thus the actuator  29  fails to be used again. Since the actuator  29  is a costly component of the camera module  2 , discarding the actuator  29  increases the fabricating cost of the camera module  2 . According to the key feature of the present invention, a cleaning hole  25  is formed in a sidewall  240  of the lens holder  24 . The cleaning hole  25  is filled with a removable sealing stuff  26 . The material of the sealing stuff  26 , the procedure of removing the sealing stuff  26 , the selection of the cleaning hole  25  and the variants of the cleaning procedure are similar to those illustrated above, and are not redundantly described herein. 
         [0038]      FIG. 6  is a schematic view illustrating a device for cleaning the camera module shown in  FIG. 3 . In this embodiment, the pollutant is removed by a blowing means. Similarly, the inner surface  249  of the lens holder  24  has been previously coated with a layer of viscous substance  27 . When the pollutant is blown up by the gas introduced from the cleaning tool  32 , the pollutant will be adherent onto the inner surface  249  of the lens holder  24  in order to preventing the pollutant from returning back the imaging region of the image sensor  22  again. 
         [0039]    For facilitating the fabrication of the camera module  2 , before the camera module  2  is assembled, the cleaning hole  25  is created in the lens holder  24 , the cleaning hole  25  is filled with the sealing stuff  26 , and the inner surface  249  of the lens holder  24  is coated with a layer of viscous substance  27 . During the assembling process of the camera module  2 , the image sensor  22  is mounted on the printed circuit board  23 , then the lens holder  24  is fixed on the printed circuit board  23 , then the actuator  29  is combined with the lens holder  24 , and finally the lens module  21  is combined with the lens holder  24 . After the camera module  2  is assembled, a testing procedure is performed to detect whether any pollutant is present within the assembled camera module  2 . For performing the testing procedure, the electrical contacts (not shown) on the periphery of the image sensor  22  should be electrically connected with a display device (not shown). Via the display device, it can be observed and determined whether there is any pollutant (e.g. particle, dust or dirt) adversely influencing the image quality according to the captured image. Once any pollutant is detected, the sealing stuff  26  is removed from the cleaning hole  25  such that the cleaning procedure can be performed through the cleaning hole  25 . After the cleaning procedure is completed, the cleaning hole  25  is filled with the sealing stuff  26  again, and the testing procedure is performed again. The cleaning procedure and the testing procedure could be repeatedly implemented until the tester assures that pollutant (e.g. particle, dust or dirt) adversely influencing the image quality is no longer present within the camera module  2 . 
         [0040]    The method of cleaning the camera module according to the present invention can be carried out during the process of assembling and testing the camera module. In a case that the camera module is returned to the depot service for repair or maintenance, the cleaning method is also feasible. In addition, some mobile pollutants are not detectable by the testing procedure in the factory, but possibly fall into the imaging region if the camera module is suffered from vibration during transportation or usage. By removing the sealing stuff from the cleaning hole, cleaning the internal portion of the camera module and filling the cleaning hole with the sealing stuff again, the maintenance worker can quickly deal with such problem. 
         [0041]    From the above description, the method of cleaning the camera module according to the present invention is very simple and time-saving. In addition, the possibility of damaging the components of the camera module is reduced. Since it is not necessary to separate the lens module from the lens holder by the cleaning method of the present invention, the secondary pollution problem resulted from recombination of the lens module and the lens holder will be avoided. 
         [0042]    While the invention has been described in terms of what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention needs not be limited to the disclosed embodiment. On the contrary, it is intended to cover various modifications and similar arrangements included within the spirit and scope of the appended claims which are to be accorded with the broadest interpretation so as to encompass all such modifications and similar structures.