Abstract:
An apparatus is configured for use with a digital camera to capture images of a fingerprint with the camera. The digital camera includes a primary lens for general photography purposes. The apparatus includes an accessory lens assembly including a first surface for supporting a finger to be imaged. The accessory lens assembly is configured to direct light reflected from the finger to the primary lens of the digital camera. A connection mechanism connects the accessory lens assembly to the digital camera. The accessory lens assembly is movable via the connection mechanism to cover the primary lens for fingerprint imaging, and is movable via the connection mechanism away from the primary lens to allow the digital camera to be used for general photography purposes.

Description:
THE FIELD OF THE INVENTION  
         [0001]    This invention relates generally to digital cameras. This invention relates more particularly to an electronic device with a digital camera configured to be used as both a general-purpose camera and a fingerprint sensor.  
         BACKGROUND OF THE INVENTION  
         [0002]    Many electronic devices, such as cellular telephones and personal digital assistants (PDAs), have the need for a digital camera to be included in the design. Such combined devices have been manufactured. The digital cameras for such combined devices are designed for general photography use. In addition to the primary lens in a digital camera, some models allow the use of accessory lenses. The use of accessory lenses is a common technique for changing the way the primary lens of the camera works. Such commonly used accessory lenses include wide angle, telephoto, and macro lens attachments.  
           [0003]    Fingerprint recognition systems have also been developed. Incorporating a fingerprint recognition system into an electronic device provides security and authentication of the user. Existing fingerprint recognition systems use their own dedicated optics and image sensor for capturing images of fingerprints. Thus, for example, if a conventional fingerprint recognition system were incorporated into a digital camera, or a combined electronic device that included a digital camera, two independent sets of optics and image sensors would be needed.  
           [0004]    It would be desirable to provide an accessory lens assembly that includes a lens/illumination system and a suitable surface for imaging a finger, and thereby be able to make use of the existing optics and image sensor of an electronic device that includes a digital camera to provide fingerprint recognition functionality.  
         SUMMARY OF THE INVENTION  
         [0005]    One form of the present invention provides an apparatus configured for use with a digital camera to capture images of a fingerprint with the camera. The digital camera includes a primary lens for general photography purposes. The apparatus includes an accessory lens assembly including a first surface for supporting a finger to be imaged. The accessory lens assembly is configured to direct light reflected from the finger to the primary lens of the digital camera. A connection mechanism connects the accessory lens assembly to the digital camera. The accessory lens assembly is movable via the connection mechanism to cover the primary lens for fingerprint imaging, and is movable via the connection mechanism away from the primary lens to allow the digital camera to be used for general photography purposes. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]    [0006]FIG. 1A is a diagram illustrating a simplified front view of a prior art digital camera.  
         [0007]    [0007]FIG. 1B is a diagram illustrating a simplified rear view of the digital camera shown in FIG. 1A.  
         [0008]    [0008]FIG. 2 is a diagram illustrating a simplified front view of a digital camera configured to be used as both a general-purpose camera and a fingerprint sensor according to one embodiment of the present invention.  
         [0009]    [0009]FIG. 3A is a diagram illustrating an attachment for a digital camera for facilitating fingerprint sensing according to one embodiment of the present invention.  
         [0010]    [0010]FIG. 3B is a diagram illustrating the attachment shown in FIG. 3A in a down position.  
         [0011]    [0011]FIG. 3C is a diagram illustrating the attachment shown in FIG. 3B with the addition of a light source for illuminating a finger to be imaged.  
         [0012]    [0012]FIG. 4 is a block diagram illustrating major components of the digital camera shown in FIG. 2.  
         [0013]    [0013]FIG. 5A is a diagram illustrating a front side of a combined cellular telephone and digital camera device configured to scan fingerprints according to one embodiment of the present invention.  
         [0014]    [0014]FIG. 5B is a diagram illustrating a back side of the combined cellular telephone and digital camera device shown in FIG. 5A.  
         [0015]    [0015]FIG. 6 is a diagram illustrating a front side of a combined cellular telephone and digital camera device configured to scan fingerprints according to an alternative embodiment of the present invention. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0016]    In the following detailed description of the preferred embodiments, reference is made to the accompanying drawings, which form a part hereof, and in which is shown by way of illustration specific embodiments in which the invention may be practiced. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present invention. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims.  
         [0017]    [0017]FIG. 1A is a diagram illustrating a simplified front view of a prior art digital camera  100 . FIG. 1B is a diagram illustrating a simplified rear view of the digital camera  100  shown in FIG. 1A. As shown in FIGS. 1A and 1B, camera  100  includes shutter button  102 , optical viewfinder  104 , flash  106 , primary lens  108 , liquid crystal display (LCD)  112 , and user input device  114 . User input device  114  includes buttons  114 A- 114 C. User input device  114  allows a user to enter data and select various camera options.  
         [0018]    In operation, a user looks through optical viewfinder  104  or at LCD  112  and positions camera  100  to capture a desired image. When camera  100  is in position, the user presses shutter button  102  to capture the desired image. An optical image is focused by primary lens  108  onto image sensor  400  (shown in FIGS.  3 A- 3 C and  4 ), which generates pixel data that is representative of the optical image. Captured images are displayed on display  112 . Flash  106  is used to illuminate an area to capture images in low-light conditions.  
         [0019]    [0019]FIG. 2 is a diagram illustrating a simplified front view of a digital camera  200  configured to be used as both a general-purpose camera and a fingerprint sensor according to one embodiment of the present invention. In one embodiment, camera  200  includes the same features as camera  100 , and also includes fingerprint attachment  202 . Fingerprint attachment  202  includes lens assembly  202 A and hinge  202 B. Fingerprint attachment  202  is mounted to the front face of camera  200  via hinge  202 B. Lens assembly  202 A is configured to rotate about hinge  202 B, so that lens assembly  202 A may be positioned over primary lens  108  (as shown in FIG. 2) for capturing fingerprint images, or rotated away from primary lens  108  (as shown in FIG. 3A) for general-purpose photography.  
         [0020]    [0020]FIG. 3A is a diagram illustrating fingerprint attachment  202  in an up position, so it is not covering primary lens  108  of digital camera  200 . When fingerprint attachment  202  is in an up position, digital camera  200  may be used for general-purpose photography, with light  300  being directed by primary lens  108  onto image sensor  400 .  
         [0021]    [0021]FIG. 3B is a diagram illustrating fingerprint attachment  202  in a down position, so it is covering primary lens  108  of digital camera  200 . When fingerprint attachment  202  is in a down position, digital camera  200  may be used to scan fingerprints. As shown in FIG. 3B, finger  302  is placed on surface  202 C of attachment  202 . In one embodiment, surface  202 C is a flat, transparent, soft surface, such as glass with a thin layer of silicon rubber deposited thereon, or other transparent, soft, compliant material. Using such a soft surface facilitates imaging of the grooves in the finger, particularly for dry skin. Light  300  reflected off of finger  302  goes through a hollow chamber  202 D of attachment  202 , and is directed by lens  202 E onto primary lens  108 , which directs the light  300  onto image sensor  400 . Image sensor  400  captures an image of the fingerprint. In an alternative embodiment, little or no spacing is provide between surface  202 C and lens  202 E. In another alternative embodiment, rather than using a separate surface  202 C for placement of a finger, and having a hollow chamber  202 D between the surface  202 C and the lens  202 E, a finger is placed directly on lens  202 E. So in this alternative embodiment, lens  202 E provides both a close focusing capability and a surface for placement of a finger.  
         [0022]    In one embodiment, lens  202 E is a custom lens, such as a Fresnel lens or a diffractive lens. In an alternative embodiment, lens  202 E is a conventional macro lens. Fresnel, diffractive, and macro lenses all perform the same function, which is to provide the close focusing capability that is needed for imaging micro-features like the whorls of skin in a finger. Fresnel lenses include several prism pieces, and rely on the optical property of refraction. Diffractive lenses include small grooved features to create constructive and destructive interference in the wave front of the light. Macro lenses are conventional lenses with two convex surfaces. Fresnel and diffractive lenses can be made very small, which is desirable for small electronic devices, such as cellular telephones, PDA&#39;S, and other similar devices.  
         [0023]    [0023]FIG. 3C is a diagram illustrating the attachment  202  shown in FIG. 3B, with the addition of a light source  202 F for illuminating a finger placed on surface  202 C. In one embodiment, light source  202 F is a light emitting diode (LED). In one form of the invention, light source  202 F is configured to provide light  300  at a grazing angle, such as an angle between about 5 to 10 degrees relative to surface  202 C, although other angles may be used. In an alternative embodiment, fingerprint attachment  202  uses total internal reflection to provide more contrast and an easier to photograph image of the fingerprint. With total internal reflection, light rays directed toward portions of surface  202 C that are covered by air are reflected, causing these portions to appear bright in the reflected image. And light rays directed toward other portions of surface  202 C are transmitted through surface  202 C, causing these portions to appear dark in the reflected image.  
         [0024]    [0024]FIG. 4 is a block diagram illustrating major components of digital camera  200 . Camera  200  includes fingerprint attachment  202 , primary lens  108 , image sensor  400 , shutter controller  404 , processor  406 , memory  408 , input/output (I/O) interface  412 , shutter button  102 , LCD  112 , and user input device  114 . In one embodiment, memory  408  includes some type of random access memory (RAM) and non-volatile memory, but can include any known type of memory storage. In operation, when a user presses shutter button  102 , processor  406  and shutter controller  404  cause image sensor  400  to capture an image. Image sensor  400  then outputs pixel data representative of the image to processor  406 . The pixel data is stored in memory  408 , and captured images may be displayed on LCD  112 .  
         [0025]    Control software  410  for controlling processor  406  is stored in memory  408 . In one form of the invention, control software  410  includes software for analyzing captured fingerprint images to verify the user of digital camera  200 . After camera  200  has captured a fingerprint image, control software  410  performs a conventional matching algorithm to determine whether the captured fingerprint image matches a stored fingerprint image. Algorithms for performing fingerprint comparison and matching functions are known to those of ordinary skill in the art. In one embodiment, camera  200  is configured to limit access to various features of camera  200 , such as capturing images and viewing previously captured images, to only authorized users who have previously had their fingerprint images stored in memory  408  and pass a fingerprint verification. In one form of the invention, any time camera  200  is powered on, the user&#39;s identity must be verified by having the user&#39;s fingerprint scanned with camera  200  before camera  200  can be operated.  
         [0026]    I/O interface  412  is configured to be coupled to a computer or other appropriate electronic device (e.g., a personal digital assistant), for transferring information between the electronic device and camera  200 , including downloading captured images from camera  200  to the electronic device.  
         [0027]    [0027]FIG. 5A is a diagram illustrating a front side of a combined cellular telephone and digital camera device  500  configured to scan fingerprints according to one embodiment of the present invention. FIG. 5B is a diagram illustrating a back side of the combined cellular telephone and digital camera device  500  shown in FIG. 5A. Device  500  includes upper portion  500 A and lower portion  500 B, which may be rotated about hinge  510  to go from an open position (as shown in FIG. 5A) to a closed position, as is common with many current cellular telephone models. Device  500  includes antenna  502 , speaker  504 , primary digital camera lens  506 , LCD  508 , navigation and control buttons  512 , numeric keypad  514 , and fingerprint lens assembly  516 . As will be understood by one of ordinary skill in the art, in addition to including primary lens  506 , the digital camera of device  500  also includes conventional internal camera components (not shown in FIG. 5A), such as those shown in FIG. 4 (e.g., image sensor  400 , shutter controller  404 , processor  406 , and memory  408 ).  
         [0028]    In addition to displaying information regarding cellular telephone operation, LCD  508  is also used as a viewfinder for the digital camera of device  500 , and displays captured images. Although no optical viewfinder is shown for device  500 , it will be understood by a person of ordinary skill in the art that device  500  could incorporate an optical viewfinder, as well as any other conventional features of currently available digital cameras.  
         [0029]    Navigation and control buttons  512  and numeric keypad  514  are used to enter information, navigate through menus displayed on LCD  508  and select menu items, and control operation of device  500 . Any one of buttons  512  or  514  may be designated as a shutter button  102  for capturing images with the digital camera of device  500 , or a dedicated shutter button  102  can be provided.  
         [0030]    In one embodiment, fingerprint assembly  516  is configured similarly to fingerprint attachment  202  (shown in FIGS. 2 and 3A- 3 C), and includes a transparent surface  202 C (shown in FIG. 5B) on the back side of device  500  for placing a finger on, a lens  202 E on the front side of device  500  for directing light reflected from the finger to the primary lens  506 , and a hollow chamber  202 D between the surface  202 C and the lens  202 E. In one embodiment, fingerprint assembly  516  also includes a light source  202 F for illuminating the finger.  
         [0031]    Device  500  is configured to act as a fingerprint sensor when upper portion  500 A and lower portion  500 B are folded together via hinge  510  into a closed position. When device  500  is in the closed position, lens  202 E of fingerprint assembly  516  is aligned with primary lens  506 . A finger is placed on surface  202 C on the back side of device  500 . Light reflected off of the finger goes through a hollow chamber  202 D of assembly  516 , and is directed by lens  202 E onto lens  506 , which directs the light onto an image sensor  400  within device  500 . Image sensor  400  captures an image of the fingerprint.  
         [0032]    [0032]FIG. 6 is a diagram of a front side of a combined cellular telephone and digital camera device  600  configured to scan fingerprints according to an alternative embodiment of the present invention. As shown in FIG. 6, device  600  is in a closed position. Device  600  includes antenna  602 , primary digital camera lens  604 , tracks  606 A and  606 B (collectively referred to as tracks  606 ), and fingerprint assembly  608 . Fingerprint assembly  608  is configured to slide along tracks  606 .  
         [0033]    In one embodiment, fingerprint assembly  608  is configured similarly to fingerprint attachment  202  (shown in FIGS. 2 and 3A- 3 C), and includes a transparent surface  202 C on the top side of assembly  608  for placing a finger on, a lens  202 E (not shown in FIG. 6) on the bottom side of assembly  608  for directing light reflected from the finger to the primary lens  604 , and a hollow chamber  202 D between the surface  202 C and the lens  202 E. In one embodiment, fingerprint assembly  608  also includes a light source  202 F for illuminating the finger.  
         [0034]    Device  600  is configured to act as a fingerprint sensor when fingerprint assembly  608  is slid upward along tracks  606  to cover lens  604 . Device  600  can act as a fingerprint sensor whether the device  600  is in the open position (e.g., such as shown in FIGS. 5A and 5B) or in the closed position as shown in FIG. 6. After sliding fingerprint assembly  608  into place over lens  604 , a finger is placed on surface  202 C of assembly  608 . Light reflected off of the finger goes through a hollow chamber  202 D of assembly  608 , and is directed by lens  202 E onto lens  604 , which directs the light onto an image sensor  400  within device  600 . Image sensor  400  captures an image of the fingerprint.  
         [0035]    In one embodiment, devices  500  and  600  each include a processor  406  and control software  410  stored in a memory  408  (shown in FIG. 4) to control operation of the devices and to capture and process fingerprint images to verify the user of the device. In one embodiment, devices  500  and  600  are configured to limit access to various features of the devices, such as capturing images and viewing previously captured images, to only authorized users who have previously had their fingerprint images stored in memory  408  and pass a fingerprint verification. In one form of the invention, any time devices  500  and  600  are powered on, the user&#39;s identity must be verified by having the user&#39;s fingerprint scanned with digital camera before the devices can be operated.  
         [0036]    Although embodiments of the present invention have been discussed in the context of a combined cellular telephone/digital camera device, it will be understood by a person of ordinary skill in the art that the techniques disclosed herein are applicable to any device that incorporates a digital camera, including but not limited to, a PDA and a laptop computer. For example, many PDA&#39;s include a cover that flips up and down to cover the PDA display, similar to the manner in which some cellular phones can be flipped open and closed. For such PDA&#39;s, a fingerprint assembly (e.g., such as fingerprint assembly  516  shown in FIG. 5A) can be incorporated into the cover, so that a digital camera of the PDA can be used for general photography purposes when the cover is open, and be used for imaging fingerprints when the cover is closed. Similarly, most laptop computers are configured with a hinge connection between the monitor and the keyboard. If the laptop computer includes a digital camera, the camera could be used for general photography purposes when the laptop computer is in the open position, and could be used for fingerprint scanning when the laptop computer is in the closed position.  
         [0037]    A couple of different techniques have been described herein for mechanically attaching a fingerprint assembly to an electronic device. For example, FIG. 2 illustrates a hinge type attachment, and FIG. 6 illustrates a sliding track type attachment. It will be understood by a person of ordinary skill in the art that other types of mechanical, or electromechanical attachment mechanisms may be used to implement embodiments of the present invention.  
         [0038]    It will be understood by a person of ordinary skill in the art that functions performed by devices  200 ,  500 , and  600 , including functions performed by control software  410 , may be implemented in hardware, software, firmware, or any combination thereof. The implementation may be via a microprocessor, programmable logic device, or state machine. Components of the present invention may reside in software on one or more computer-readable mediums. The term computer-readable medium as used herein is defined to include any kind of memory, volatile or non-volatile, such as floppy disks, hard disks, CD-ROMs, flash memory, read-only memory (ROM), and random access memory.  
         [0039]    Although specific embodiments have been illustrated and described herein for purposes of description of the preferred embodiment, it will be appreciated by those of ordinary skill in the art that a wide variety of alternate and/or equivalent implementations may be substituted for the specific embodiments shown and described without departing from the scope of the present invention. Those with skill in the chemical, mechanical, electro-mechanical, electrical, and computer arts will readily appreciate that the present invention may be implemented in a very wide variety of embodiments. This application is intended to cover any adaptations or variations of the preferred embodiments discussed herein. Therefore, it is manifestly intended that this invention be limited only by the claims and the equivalents thereof.