Abstract:
A portable device having fingerprint recognition function includes an image sensing unit, a microprocessor, a signal transmitting unit, a carrying member, a cleaning unit, and a housing. It is characterized that the cleaning unit removes residual fingerprint from the image sensing unit while the carrying member moves in and out of the housing. The portable device of the present invention is free from fingerprint residue and can reduce security risks.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a portable device. More particularly, the present invention relates to a portable device which has fingerprint recognition function. 
     BACKGROUND OF THE INVENTION 
     Fingerprint recognition or fingerprint authentication refers to the automated method of verifying a match between two human fingerprints. Fingerprint readers (or modules) are commonly used devices to meet such requirement. Fingerprints are one of many forms of biometrics used to identify individuals and verify their identity. There are two major classes of algorithms (minutia and pattern) and four sensor designs (optical, ultrasonic, passive capacitance, and active capacitance) wildly used in fingerprint readers or modules. 
     There are two inexpensive fingerprint readers having been developed and grown fast in recent years. One is the optical scanner. It utilizes a Charge-Coupled Devices (CCD) or CMOS Image Sensor (CIS) to digitize fingerprints on the fingertip. The other is the capacitance-measuring type, usually made as semiconductor chips, fingerprint reader. It uses tiny capacitors to sense the fingerprint pattern on the fingertip. Both the two devices mentioned above capture fingerprint images for software algorithms to analyze geometric patterns of the feature points, for example, the ridges and grooves of each finger. Then, a comparison between the captured image and those from the fingerprint of the legal login user can be performed. 
     All the types of fingerprint reader may suffer the fingerprint residue problem, which may reduce the performance of the fingerprint recognition algorithm, or even endanger security. 
     A fingerprint reader can be a personal device and used by a single user. For example, a fingerprint reader on a notebook computer replaces the password entry method to initiate operation system by a registered fingerprint image. A fingerprint reader can also be used by a group of people. For instance, a fingerprint reader in an access control system allows entrance of specified staffs of a company by identifying their fingerprints. For the later case, if a user has a greasy finger, the fingerprint residual left on the fingerprint reader will reduce the image quality of the captured fingerprint and then affect the accuracy of the system. More importantly, for the portable fingerprint devices, the fingerprint residual left on the image sensing surface means a high security risk, because the fingerprint image can be recovered from the fingerprint residue with known retrieval techniques. 
     There are different ways to eliminate residual of fingerprints. For example, please refer to  FIG. 1  which discloses an optical fingerprint imaging system of U.S. Pat. No. 7,515,252. It includes an optically transparent platen  1  and a protective film  2  removably attached to the platen  1  with an adhesive  3 . The protective film  2  protects the platen  1  from scratches, pits, containment, and other surface damage and is substantially chemically inert to petroleum-based substances which may come into contact when receiving a finger  4  pressed to take a fingerprint image. The adhesive  3  has a selected cohesive strength that allows the protective film  2  and adhesive  3  to be removed from the platen  1  without leaving behind an adhesive residue. The protective film  2  can be replaced periodically as part of maintenance of the platen  1  to allow continued acquisition of accurate fingerprint images. Although residual of fingerprints may be eliminated by the aforementioned method, it requires the transparent platen and the protective film which cause inconvenience in use and extra cost for fingerprint recognition. 
     Fingerprint residual can also be eliminated by use of lipolytic enzymes. For example, please refer to  FIG. 2 . It discloses a substrate  5  surface having self-cleaning function by forming an anti-fingerprint film  6  with a porous structure thereon. When the porous structure including a lipolytic enzyme is formed on the surface of the substrate  5 , contaminants  7  decomposed by an enzyme are absorbed into a pore, and thus detectable contamination  7  from a surface of the substrate  5  can be removed by the anti-fingerprint film  6 . By this way, contamination or fingerprint residuals on the surface of a display device or electronic device can be effectively reduced. However, the porous structure may not be strong enough to bear friction of the finger after many times of use. 
     Therefore, a portable device having fingerprint recognition function and is free from residual fingerprint is desperately desired. 
     SUMMARY OF THE INVENTION 
     This paragraph extracts and compiles some features of the present invention; other features will be disclosed in the follow-up paragraphs. It is intended to cover various modifications and similar arrangements included within the spirit and scope of the appended claims. 
     In accordance with an aspect of the present invention, a portable device having fingerprint recognition function includes an image sensing unit for capturing fingerprint images of a finger; a microprocessor, linked to the image sensing unit, for recording the fingerprint image of the finger, identifying the fingerprint image of the finger from a fingerprint database, receiving a command signal and transmitting a response signal; a signal transmitting unit, connected to the microprocessor, for transmitting the command signal and the response signal between the microprocessor and a command device separated from the portable device; a carrying member for carrying the image sensing unit, the microprocessor, and the signal transmitting unit; and a housing, having a cleaning unit, for confining the carrying member to move partially in and out of the housing. The cleaning unit removes residual fingerprint from the image sensing unit while the carrying member moves in and out of the housing. 
     Preferably, the portable device further includes a memory unit, linked to the microprocessor, for storing the fingerprint database. 
     Preferably, the cleaning unit is a cloth, soft blade or brush. 
     Preferably, the command device includes a software for sending the command signal for the microprocessor to execute specified functions. 
     Preferably, the command device is a notebook computer, a desktop computer, a mobile phone, or fingerprint secured door look. 
     Preferably, the signal transmitting unit is a USB port or a wireless communication device such as a 2.4 Ghz or Bluetooth transmitting module. 
     Preferably, the response signal is a response of the command signal. 
     Preferably, the response signal includes a message that indicates whether the fingerprint image of the finger match a corresponding fingerprint record stored in the fingerprint database or not. 
     Preferably, the housing includes a first opening for exposing the image sensing unit while the carrying member is pushed out of the housing. 
     Preferably, the housing includes a second opening for the signal transmitting unit to be pushed out of the housing. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows an optical fingerprint imaging system of a prior art. 
         FIG. 2  shows a porous anti-fingerprint film of another prior art. 
         FIG. 3  shows a portable fingerprint device according to an embodiment of the present invention. 
         FIG. 4  illustrates a cross-sectional view of the portable fingerprint device of the present invention. 
         FIG. 5  shows another cross-sectional view of the portable fingerprint device of the present invention. 
         FIG. 6  illustrates a schematic block diagram of the portable fingerprint device of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The present invention will now be described more specifically with reference to the following embodiment. 
     Please refer to  FIG. 3  to  FIG. 6 .  FIG. 3  shows a portable fingerprint device according to an embodiment of the present invention.  FIG. 4  illustrates a cross-sectional view of the portable fingerprint device.  FIG. 5  shows another cross-sectional view of the portable fingerprint device.  FIG. 6  illustrates a schematic block diagram of the portable fingerprint device. 
     As shown in  FIG. 6 , a portable fingerprint device  10  which has fingerprint recognition function includes an image sensing unit  101 , a microprocessor  102 , a signal transmitting unit  103 , a memory unit  104 , a carrying member  105  and a housing  106 . The image sensing unit  101  is used for capturing fingerprint images of a finger. In this embodiment, the image sensing unit  101  is a capacitance-measuring type fingerprint reader. The microprocessor  102  is linked to the image sensing unit  101 . The microprocessor  102  can record the fingerprint image of the finger, identify the fingerprint image of the finger from a fingerprint database, receive a command signal and transmit a response signal. 
     The signal transmitting unit  103  is connected to the microprocessor  102  and can transmit the command signal and the response signal between the microprocessor  102  and a command device  20 . The command device  20  is separated from the portable fingerprint device  10 . The connection is presented by a dashed line shown in  FIG. 6 . In the present embodiment, the signal transmitting unit  103  is a USB male connector. The memory unit  104  is linked to or embedded within the microprocessor  102 . The memory unit  104  stores the fingerprint database. The carrying member  105  carries the image sensing unit  101 , the microprocessor  102 , the signal transmitting unit  103  and the memory unit  104  if not embedded within the microprocessor  102 . Please refer to  FIG. 4  and  FIG. 5 . By using a pushing bar  107 , the carrying member  105  can move partially in and out of the housing  106 . In this way, the signal transmitting unit  103  can protrude out of the housing  106  when the portable fingerprint device  10  needs to connect to the command device  102 , and stow back in the housing  106  when the portable fingerprint device  10  is not used and needs protection of the housing  106 . 
     The housing  106  is used to enclose and protect the image sensing unit  101 , the microprocessor  102 , the signal transmitting unit  103  and the memory unit  104  and the carrying member  105 . The housing  106  has a cleaning unit  1061  inside. As mentioned above, the housing  106  can confine the carrying member  105  to move partially in and out of the housing  106 . In the present embodiment, the cleaning unit  1061  is a cloth. The material of the cloth should be soft enough so that when it moves across the surface of the image sensing unit  101 , the surface won&#39;t be scratched. In practice, the cleaning unit  1061  can use a soft blade or brush instead. As shown in  FIG. 4  and  FIG. 5 , it is obvious that the cleaning unit  1061  removes residual fingerprint from the image sensing unit  101  while the carrying member  105  moves in and out of the housing  106 . That means the cleaning unit  1061  wipes out the residual fingerprint or dust on the image sensing unit  101 . The housing  106  further has a first opening  1062  and a second opening  1063 . The first opening  1062  is used for exposing the image sensing unit  101  while the carrying member  105  is pushed out of the housing  106 . The second opening  1063  is used for the signal transmitting unit  103  to be pushed out of the housing  106 . 
     In this embodiment, the portable fingerprint device  10  is a USB mass storage device. The portable fingerprint device  10  uses a USB male connector to transmit data and connect with the command device  20 , which can be a notebook or desktop computer. According to the spirit of the present invention, the portable fingerprint device  10  is not limited to the USB drive mass storage device. It can be any device which has the image sensing unit  101  needed to be cleaned. The signal transmitting unit  103  can also be a wireless communication device such as a 2.4 Ghz or Bluetooth transmitting module instead. 
     From the aforementioned description, it is easily known how the portable fingerprint device  10  functions. When a user initiates the portable fingerprint device  10  by scanning his fingerprint by the image sensing unit  101 , the fingerprint image data is sent to the microprocessor  102 . The microprocessor  102  will identify the fingerprint image of the finger from the fingerprint database in the memory unit  104  to check if the fingerprint is registered or not. After receiving a command signal from the command device  20 , the microprocessor  102  will act as the command signal requests. For example, the microprocessor  102  will allow user to use other data stored in the memory unit  104  according to the command signal. Finally, the microprocessor  102  requests the signal transmitting unit  103  to transmit the response signal back to the command device  20  to let the command device  20  know what has been done according to the command signal. The response signal includes a message that indicates whether the fingerprint image of the finger match a corresponding group fingerprints in the fingerprint database or not. The response signal is also a response of the command signal. 
     In order to facilitate use of the command device  20 , the command device  20  has a software. The software can control the microprocessor  102  to perform functions based on the result of fingerprint identification via the command signal. For example, the microprocessor  102  may deliver user requested data stored in the memory unit  104  if the fingerprint identification result is positive, or transmit a response signal that includes a message indicating a failure of fingerprint match. 
     According to the present invention, it should be noticed that the command device  20  can be a notebook computer, a desktop computer, a mobile phone, or fingerprint secured door look. 
     While the invention has been described in terms of what is presently considered to be the most practical and preferred embodiment, 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.