Abstract:
A digital camera module includes a first barrel ( 10 ), a second barrel ( 20 ), a beam splitter ( 30 ), an IR-cut filter ( 40 ) and an image sensor ( 50 ). The first barrel receives a first lens element group ( 12 ) therein. The second barrel receives a second lens element group ( 22 ). The beam splitter is located between the first lens element group and the second lens element group. The presence of the beam splitter may effectively facilitate a decrease in the thickness needed to fit an optical path of a required length (to accommodate optics necessary for high resolution) within a mobile electronic device (e.g., phone, PDA), allowing a portion of the optical path to be positioned in the longer, vertical direction of the device body. This digital camera facilitates the miniaturization of a portable electronic device.

Description:
BACKGROND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to digital camera modules and, particularly, to a thin digital camera module and a mobile/cellular phone using the thin digital camera module.  
         [0003]     2. Discussion of the Invention  
         [0004]     In recent years, digital cameras have been rapidly becoming widespread. Such digital cameras convert an optical image to electronic signals by using an image sensor such as a charge coupled devices (CCD) or a complementary metal-oxide semiconductor (CMOS) sensor instead of silver halide film, convert the data to digital form, and record or transfer the digitized data. In such digital cameras, since a CCD and a CMOS sensor each have high number of pixels (about between two million pixels and three million pixels), a high performance digital camera module mounted with an image sensor is in greatly increasing demand. In particular, a compact digital camera is desired. Further, in recent years, digital cameras have been becoming incorporated in or externally attached to personal computers, web cams, mobile computers, mobile telephones, PDAs and the like, which further spurs the demand for a thin digital camera.  
         [0005]     The conventional digital camera includes a barrel and an image sensor. Several lens elements are secured in the barrel. The image sensor is located behind the lens elements. The lens elements and the image sensor are disposed on the same optical axis. Accordingly, a thickness of digital camera greatly depends on a thickness of the module, in the optical axis direction. In order to decrease the thickness of the digital camera, the axis-direction thickness has been decreased by means of decreasing the number of lens elements. However, a good image quality is still desired, even under the condition of reduction of the number of lens elements to reduce the module thickness. For a low-resolution digital camera, fewer lens elements indeed may be employed, thereby reducing the thickness of digital camera. Nevertheless, in order to achieve the resolution level desired for high-resolutions digital camera (e.g., about eight mega pixels), the full complement of lens elements is needed to satisfy some requirements so as to secure a better image quality. Thus, with the increasing digital camera&#39;s pixel requirements, the axis-direction thickness of previously-available digital cameras have increased accordingly. As such, digital cameras with lens elements aligned along a single axis cannot effectively satisfy the requirement of miniaturization.  
         [0006]     Therefore, a thin digital camera module is desired in order to overcome the above-described shortcomings.  
       SUMMARY OF THE INVENTION  
       [0007]     A thin digital camera module is provided, which may be incorporated in or externally attached to portable electronic devices such as mobile computers, PDAs, mobile phones, etc.  
         [0008]     The digital camera module is suitable for a digital camera in a foldable electronic device. A preferred embodiment of the digital camera module includes a first barrel, a second barrel, and a reflection apparatus. The first barrel receives a first lens element group therein. The second barrel receives a second lens element group therein, and the second barrel connects with the first barrel in a range of angles. The reflection apparatus is located between the first lens element group and the second lens element group. The effective thickness of the digital camera may be decreased. This thickness decrease is achieved by providing two optical axis directions, instead of only one, to accommodate all the desired lens elements.  
         [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 to scale, the emphasis instead being placed upon clearly illustrating the principles of the present digital camera module and its potential applications. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views.  
         [0011]      FIG. 1  is a cut-away view of a digital camera according to one embodiment;  
         [0012]      FIG. 2  is a top plan view of a mobile phone according to another embodiment; and  
         [0013]      FIG. 3  is a cross-sectional view taken along line III-III of  FIG. 2 , showing a digital module used in the mobile phone. 
     
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS  
       [0014]     Referring now to the drawings in detail,  FIG. 1  shows a digital camera  100  in accordance with one embodiment. A system of coordinates is defined in  FIG. 1 . The system of coordinates includes an x-axis and a z-axis, perpendicular to each other.  
         [0015]     The digital camera  100  generally includes a first barrel  10 , a second barrel  20 , a reflection or light-redirection apparatus (beam splitter  30 , as illustrated), an IR-cut filter  40 , and an image sensor  50 .  
         [0016]     The first barrel  10  is substantially a hollow cylinder. A first lens elements group  12  is received in the first barrel  10 . The first lens elements group  12  is made up of several lens elements (not individually labeled), and the first lens elements group  12  firstly receiving light rays which enter from the outside. The first barrel  10  is aligned in the z-axis direction. Also disposed in the first barrel  10  is a glass board  14 . The glass board  14  is disposed before the first lens elements group  12  and covers one end of the first barrel  10 . As such, the glass board  14  protects the first lens elements group  12  from potentially being scraped or otherwise abraded and keeps dust from entering the system.  
         [0017]     The second barrel  20  has a second lens elements group  22  mounted therein. The second lens elements group  22  is made up of several lens elements (not individually labeled). The second barrel  20  includes a housing portion  24 , a connection portion  26 , and a bottom board  28 . The housing portion  24  is aligned in the x-axis direction, and the second lens elements group  22  is received in the housing portion  24 . Thereby, an optical axis of the first lens element group  12  is perpendicular to an optical axis of the second lens element group  22 . The connection portion  26  is disposed at one end of the housing portion  24 , and one end of the connection portion  26  correspondingly communicates with the housing portion  24 . One opposite end of the connection portion  26  connects with the first barrel  10  by means of screw thread, the opposite end of the connection portion  26  connecting and communicating with the first barrel  10 . A bottom board  28  is disposed in another opposite end of the housing portion  24 .  
         [0018]     The beam splitter  30  is secured in the second barrel  20  and is located in the connection portion  26  of the second barrel  20 . The beam splitter  30  may reflect light rays from the first lens elements group  12  to the second lens elements group  22 . An optical path  31  of digital camera  100  is illustrated by a set of orthogonal lines. Essentially, the reflection or light redirection apparatus (e.g., beam splitter  30 ) provides for a change in direction within the optical path  31 . The angle of the optical path  31 , while illustrated as orthogonal, can potentially take on any of a range of angles between 0° and 180° (not inclusive), depending on the positioning of the reflection or light redirection apparatus  30 . An angle of approximately 90° (e.g., ±10°) does offer the advantage of a reduced potential for image distortion. However, depending on space requirements for camera module  100 , other angles may prove more suitable (for example, if the angle between barrels  10  and  20  must be chosen differently), with potential distortion being minimized by methods known in the imaging art.  
         [0019]     The IR-cut filter  40  is situated behind the second lens element group  22 , so as to protect the image sensor  50 . At least one surface of the IR-cut filter  40  is coated with an IR-cut coating. The IR-cut coating can filtrate infrared rays from the air so as to improve the image quality.  
         [0020]     The image sensor  50  is usually a charge-coupled device (CCD) or a complementary metal-oxide semiconductor (CMOS). The image sensor  50  is located behind the IR-cut filter  40  and is fixed on the bottom board  28  of the second barrel  20 . The image sensor  50  may transfer light signals to electronic signals.  
         [0021]     In operation, the light rays reflected from an image object (not shown) pass through the first lens elements group  12 . The first lens elements group  12  focuses the light rays, and focused light passes through the beam splitter  30 . The beam splitter  30  will lead (i.e., redirect) the light rays to the second lens elements  22 . After that, the light rays pass through the IR-cut filter  40 , and the infrared rays are filtered therefrom. At the end, the light rays arrive at the image sensor  50 . The image sensor  50  will transfer the light signal to an electronic signal, permitting the storage of the image information in a memory of the digital camera. As such, the photographic process is finished. If the image should not prove to be clear enough (i.e., out of focus), the user may adjust the first barrel  10  by hand, thereby changing the focal distance between the first barrel  10  and the second barrel  20 .  
         [0022]     In another embodiment, the digital camera can advantageously be used in portable electronic devices such as mobile phones. Referring to  FIG. 2  and  FIG. 3 , the mobile phone  60  includes a body  61  and incorporates a digital camera  200 . One end of the body  61  disposes a display  62 , while another opposite end of the body  61  has a keypad  63  disposed thereon. A printed circuit board  68  is housed in the body  61  of the mobile phone  60 . An optical opening  66  is defined in a middle of the body  61  of the mobile phone  60 , in the side opposite to the side carrying the display  62  of the mobile phone  60 . The body  61  has a body cavity  67  therein. A digital camera  200  is secured at or at least proximate optical opening  66  within the body cavity  67 , such that light can enter through optical opening  66  and into digital camera  200  (specifically first barrel  10 ). Accordingly, the optical opening  66  is within the optical path (not labeled in  FIG. 3 ) of the digital camera  200 .  
         [0023]     The digital camera  200  is mostly the same with the digital camera  100  of the first embodiment. A different point is that the digital camera  200  deletes the bottom board  28  and makes one end of the second barrel  20  open, since the digital camera  200  is already contained within body  61 . The image sensor  50  will connect with the printed circuit board  68  of the mobile phone  60  through lead lines (in the form of wires, printed circuitry, pin connectors, etc., depending on the system configuration). The embodiment of the invention may fully use the x-axis direction space and greatly decrease the z-axis height, which would help satisfy the requirement of the camera miniaturization for the portable electronic device.  
         [0024]     In still further alternative embodiments, the first barrel  10  is connected with the second barrel  20  at any of a variety of angles, between 0° and 180°, not inclusive. The first barrel  10  and the second barrel  20  may be molded together as a whole during manufacture (molding offers the advantage of simplified manufacture but eliminates the opportunity of manual focus). Alternatively, the first barrel  10  may be fixed relative to the second barrel  20  by means of a glue or other adhesive or by a plastic welding procedure. The connection portion  24  may be separate from the second barrel  20 , making both ends of the second barrel  20  open. The end opposite to the bottom board  28  could connect the connection portion  26  by means of screw thread, which may allow adjustment of the x-axis distance (i.e., facilitate focusing).  
         [0025]     In a still further alternative embodiment, the beam splitter  10  may be replaced by another reflection apparatus such as a mirror or a prism.  
         [0026]     In a still further alternative embodiment, the optical opening  66  for receiving the digital camera module may be defined in other positions of the mobile phone.  
         [0027]     It is believed that the present embodiments and their advantages will be understood from the foregoing description, and it will be apparent that various changes may be made thereto without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the examples hereinbefore described merely being preferred or exemplary embodiments of the invention.