Abstract:
A digital camera module ( 100 ) includes a lens holder ( 20 ), a lens mount ( 22 ), and an image pick-up module ( 24 ). The lens holder defining a central hollow, and has at least one lens ( 206[ check number]) received therein. The lens mount defining a central hollow, and an inner diameter of the lens holder being slightly greater than or equal to an outer diameter of the lens mount such that the lens holder capable of locating around the lens mount and movable along an axis of the lens mount. The image pick-up module is arranged so as to receive the light from the lenses.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates generally to digital camera modules and, more particularly, to a digital camera module which improves image quality.  
         [0003]     2. Discussion of the Related Art  
         [0004]     Generally, digital cameras are image recording media capable of photographing a plurality of still images without using regular film. Such a digital camera typically uses an image pickup device, which is a kind of semiconductor device, such as a charge coupled device (CCD) or complementary metal oxide semiconductor (CMOS). In the digital camera, an object image formed on the image pickup device through a lens is converted into an electrical signal by the image pickup device, and the electrical signal is stored as a digital signal in a mobile phone or PDA in which the digital camera is mounted.  
         [0005]     A digital camera module, as shown in  FIG. 3 , includes a lens barrel  10 , a lens holder  12 , and an image pick-up module  14 . The lens barrel  10  has an external thread  102 , and the lens holder  12  has an internal thread  122 . The lens barrel  10  is received in the lens holder  12  via the thread engagement between the external thread  102  and the internal thread  122 . The image pick-up module  14  includes a base plate  142  and an image pick-up chip  144 . The lens holder  12  is fixed on the base plate  142 . DuringDuring auto-focusing, a distance between the lens barrel  10  and the image pick-up chip  144  is slightly adjusted to make the digital camera module focus by means of adjusting the thread engagement of the internal thread  122  of the lens holder  12  and the external thread  102  of the lens barrel  10 . Lastly, the lens holder  12  is secured on the base plate  142  via adhesive.  
         [0006]     However, dust and/or particle pollution/contamination associated with friction between the lens barrel  10  and the lens holder  12  may fall onto the image pick-up chip  144 , thus affecting image quality of the digital camera module.  
         [0007]     What is needed, therefore, is a digital camera module, which overcomes the above-described problem.  
       SUMMARY OF THE INVENTION  
       [0008]     A digital camera module comprises a lens holder, a lens mount, and an image pick-up module. The lens holder is hollow, and has at least one lenses received therein. The lens mount is hollow, and an inner diameter of the lens holder being slightly greater than or equal to an outer diameter of the lens mount such that the lens holder capable of locating around the lens mount and movable along an axis of the lens mount. The image pick-up module is arranged to receive the light signal from the lenses.  
         [0009]     Other advantages and novel features will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]     Many aspects of the digital 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 digital camera module. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views.  
         [0011]      FIG. 1  is an schematic view of a digital camera module, in accordance with a first preferred embodiment.  
         [0012]      FIG. 2  is an schematic view of a digital camera module, in accordance with a second preferred embodiment.  
         [0013]      FIG. 3  is an schematic view of a typical digital camera module. 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0014]     Referring now to the drawings,  FIG. 1  shows a digital camera module  100  according to a first preferred embodiment. The digital camera module  100  is adapted for use in a portable electronic device (not shown), such as a mobile phone or a personal digital assistant (PDA), but the given the compact nature thereof it could prove useful in compact digital camera units or digital camcorders. The digital camera module  100  includes a lens holder  20 , a lens mount  22 , and an image pick-up module  24 . The image pick-up module  24  includes a base plate  25 , an adhesive means  26 , an image pick-up chip  27 , and a plurality of bonding wires  28 .  
         [0015]     The lens holder  20  is a hollow cylinder in shape with two open ends so that light can be transmitted therethrough. The lens holder  20  includes a first cylinder portion  202 , and a second cylinder portion  204  integrally formed with the first cylinder portion  202 . An inner diameter of the first cylinder portion  202  is smaller than that of the second cylinder portion  204 . The first cylinder portion  202  has a plurality of lenses  206  (only one shown) received therein. The second portion  204  has an internal thread  208  defined in an inner periphery thereof.  
         [0016]     The lens mount  22  is a hollow cylinder with two open ends so that light can be transmitted therethrough. The lens mount  22  has a projecting stage  222  projecting from an outer periphery thereof adjacent to a bottom thereof The lens mount  22  has an external thread  224  defined in an outer periphery thereof, corresponding to the internal thread  208  of the lens holder  20 .  
         [0017]     The base plate  25  is made of a material such as a plastic, a ceramic or a fibrous composite. The base plate  25  has a top surface  250 , a bottom surface  252  on an opposite side of the base plate  25  to the top surface  251 , a plurality of top pads  251  and a plurality of bottom pads  253 . The top pads  251  are arranged in a circular pattern on the top surface  250  of the base plate  25 . The bottom pads  253  are arranged in a circular pattern on the bottom surface  252 . The base plate  25  is used for electrically connecting the image pick-up chip  27  to other printed circuit boards.  
         [0018]     The image pick-up chip  27  attached to the top surface  250  of the base plate  25  via the adhesive means  26 , surrounded by the top pads  251 . A top side of the image pick-up chip  27  is arranged with a photosensitive area  271  and a plurality of chip pads  272  around the photosensitive area  271 .  
         [0019]     The bonding wires  28  are made of a conductive material such as gold or aluminum alloy. One end of each bonding wire  28  is connected/joined with a respective chip pad  272  of the image pick-up chip  27 , and the other end of the bonding wires  28  is connected/joined with a respective top pad  251  of the base plate  25 .  
         [0020]     The adhesive means  26 , such as a silicone, epoxy, acrylic, or polyamide adhesive, is also applied peripherally around the image pick-up chip  27 , over the bonding wires  28 . The adhesive means  26  covers the bonding wires  28  and junctions of the bonding wires  28  and the pads  272 ,  251 , in order to protect the bonding wires  28  from cracking from metal fatigue and to ensure the firm connection between the ends of the bonding wires  28  and pads  272 ,  251 . It is to be understood that the adhesive means  26  could be applied to the peripheral edge of the image pick-up chip  272  and/or over the bonding wires  28 , therefore the adhesive means  26  covers part of each bonding wire  28  and junctions between the bonding wire  283  and the chip pads  272 .  
         [0021]     In assembling the digital camera module  100 , the lens holder  20  is placed around the lens mount  22 , with the internal thread  208  engaging with the external thread  224  of the lens mount  22 . Then, the lens mount  22  is fixed on the image pick-up module  24 , with the image pick-up chip  27  received in the lens mount  22  and the lens mount  22  secured on the base plate  25 . During auto-focusing, a distance between the lens holder  20  and the image pick-up chip  27  is slightly adjusted to focus the digital camera module  100  by adjusting the thread engagement of the internal thread  208  of the lens holder  20  and the external thread  224  of the lens mount  224 .  
         [0022]     Referring to  FIG. 3 , another digital camera module  200  according to a second preferred embodiment is provided. The digital camera module  200  includes a lens holder  30 , a lens mount  32 , and an image pick-up module  34 . The image pick-up module  34  includes a base plate  35 , a flange  36 , an adhesive means  37 , an image pick-up chip  38 , a plurality of bonding wire  39 , a transparent plate  40 , and a plurality of metal plates  41 .  
         [0023]     The lens holder  30  is a hollow cylinder in shape with two open ends so that light can be transmitted therethrough. The lens holder  20  includes a first cylinder portion  302 , and a second cylinder portion  304 . An inner diameter of the first cylinder portion  302  is smaller than that of the second cylinder portion  304 . The cylinder portion  302  has a plurality of tenses  306  (only one shown) received therein. The second portion  304  has an internal thread  308  defined in an inner periphery thereof.  
         [0024]     The lens mount  32  is a hollow cylinder with two open ends so that light can be transmitted therethrough. The lens mount  32  includes an upper cylinder portion  321 , and a lower cylinder portion  322  extending from an outer periphery of the upper cylinder portion  321 . An inner diameter of the lower cylinder portion  321  is larger than that of the upper cylinder portion  321 . The upper cylinder portion  321  has an external thread  324  defined in an outer periphery thereof, corresponding to the internal thread  308  of the lens holder  30 .  
         [0025]     The base plate  35  is made of a material such as a plastic, a ceramic or a fibrous composite. The base plate  35  has a top surface  351 , and a bottom surface  352 .  
         [0026]     The flange  36  is a hollow rectangle in shape, and includes an upper surface  362  and a lower surface  364 . The lower surface  364  is adhered to the top surface  351  of the base plate  35 , defining a receiving space  346  with the base plate  35 .  
         [0027]     The image pick-up chip  38  is adhered to the top surface  351  of the base plate  35  via the adhesive means  37 . A top side of the image pick-up chip  38  is arranged with a photosensitive area  381  and a plurality of chip pads  382  around the photosensitive area  381 .  
         [0028]     The bonding wires  39  is same as the bonding wires  28 . One end of each bonding wires  38  is connected/joined with a respective chip pad  382  of the image pick-up chip  38 , and the other end of the bonding wires  39  is connected/joined with the metal plate  41 .  
         [0029]     The metal plate  41  has a first plate portion  411 , a second plate portion  413  parallel to the first plate portion  411 , and a third plate portion  412  connecting with the first plate and the second plate portion  413 . The first plate portion  411  is placed on the upper surface  362  of the flange  36 . The second plate portion  413  is adhered to the lower surface  364  of the flange  36 . The third plate portion  412  is jointed to a side of the flange  36 . The first plate portion  411  electrically connects with the bonding wires  39 , and the second plate portion  412  electrically connects with a printed circuit board.  
         [0030]     The transparent plate  40  may be a transparent glass, and is fixed on the metal plate  41 , thus sealing the photosensitive area  381  of the image pick-up chip  38 .  
         [0031]     In assembling the digital camera module  200 , the lens holder  30  places around the lens mount  32 , with the internal thread  308  engaging with the external thread  324  of the lens mount  32 . Then, the lens mount  32  is fixed on the image pick-up module  34 , with the transparent plate  40  securely received in a bottom of the lens mount  32 . During auto-focusing, a distance between the lens holder  30  and the image pick-up chip  38  is adjusted to focus the digital camera module by adjusting the thread engagement of the internal thread  308  of the lens holder  30  and the external thread  2324  of the lens mount  32 .  
         [0032]     In the embodiments, since the thread engagement between the lens holder and the lens mount is disposed on outer periphery of the lens mount, dust and/or particle pollution/contamination associated with friction between the lens holder and the lens mount can be effectively prevented from entering the pick-up module. In the second embodiment, a transparent plate  40  is disposed on the image pick-up chip  38  to completely prevent particles or dust from falling onto the image pick-up chip  38 , thus improving image quality of the digital camera module.  
         [0033]     It is to be understood, however, that even though numerous characteristics and advantages of the present embodiments have been set forth in the foregoing description, together with details of the structures and functions of the embodiments, 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.