Abstract:
A method for detecting an object and a touchable device are presented, which is capable of detecting an object having a fingerprint feature on an operation interface of the touchable device. An image sensor is used for acquiring acquiring an image on the operation interface, and the acquired image is converted into a signal denoted in a frequency domain by using a frequency conversion function. Signals at a medium-high frequency (MHF) signal region among the signals of the frequency domain are analyzed, so as to generate a first signal and a second signal according to a distribution of the signals of the frequency domain. The first signal indicates existence of the object on the operation interface, and the second signal indicates inexistence of the object on the operation interface.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This non-provisional application claims priority under 35 U.S.C. §119(a) on Patent Application No(s). 100106056 filed in Taiwan, R.O.C. on Feb. 23, 2011, the entire contents of which are hereby incorporated by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of Invention 
         [0003]    The disclosure relates to a touchable device, and more particularly to a method for detecting an object and a touchable device. 
         [0004]    2. Related Art 
         [0005]    Computers are becoming more prevalent nowadays. In order to exchange information with the computer or perform functions on the computer, people often input Information or instructions are inputted to a computer using various input devices to exchange information with the computer or perform functions on the computer. The common input device includes a mouse, a key board, and a touch pen. 
         [0006]    Keyboards are used to operate or control computers before mice are invented. After Douglas Englebart invented the first mouse in California in 1968, users begin to operate computers using mice having a button and a scroll wheel on the mouse without inputting complicated instructions through the keyboard. 
         [0007]    The computer industry has developed rapidly in recent years. For the convenience of use and carry of the computer, an optical mouse or a touchable mouse is developed in place of a mechanical mouse. 
         [0008]    In the configuration of a touchable mouse, a light source for example, a light emitting diode (LED), configured inside a body of the mouse, irradiates an operation interface. An image sensor then retrieves a finger image on the operation interface, and successively retrieved changes of the finger image are converted into a displacement amount through a corresponding image processing mechanism. The displacement amount is appropriately reflected in an amount of movement and a direction of a cursor on a computer screen. However, since an image of the external environment may also be retrieved by the image sensor, track misjudgment or jitters may occur. 
       SUMMARY OF THE INVENTION 
       [0009]    In view of the above problems, a method for detecting an object and a touchable device is disclosed, so as to solve the problems in the prior art. 
         [0010]    An embodiment of the disclosure provides a method for detecting an object applicable to a touchable device. The method for detecting the object is used for detecting an object having a fingerprint feature and placed on an operation interface of the touchable device. 
         [0011]    The method for detecting the object comprises: acquiring, by an image sensor of the touchable device, an image on the operation interface; converting the retrieved image into a signal in a frequency domain by using a frequency conversion function; and generating a first signal and a second signal according to a distribution of the signals of the frequency domain in a medium-high frequency (MHF) signal region. 
         [0012]    The first signal indicates existence of the object on the operation interface, and the second signal indicates inexistence of the object on the operation interface. 
         [0013]    An embodiment of the present disclosure provides a touchable device, where the touchable device comprises an operation interface, an image sensor, a processor, and a track detector. 
         [0014]    The image sensor is configured corresponding to the operation interface. The processor is connected to the image sensor. A displacement sensor is connected to the processor. The image sensor is used for acquiring an image on the operation interface. The processor determines whether an object exists on the operation interface by analyzing frequency components of the image acquired by the image sensor. The track detector can detect a movement track of the object on the operation interface. 
         [0015]    An embodiment of the disclosure provides a touchable device, where the touchable device comprises an operation interface, an image sensor, and a processor. 
         [0016]    The image sensor is configured corresponding to the operation interface, the processor is connected to the image sensor, and a displacement sensor is connected to the processor. The image sensor is used for acquiring an image on the operation interface. The processor determines whether an object having a fingerprint feature exists on the operation interface by analyzing frequency components of the image retrieved by the image sensor, and calculates a displacement amount of the object by using the retrieved image when the object exists on the operation interface. 
         [0017]    Moreover, a distribution of the signals can be determined by calculating energy or the number of signals in an MHF signal region and comparing the calculated value with a preset threshold value. 
         [0018]    In conclusion, the method for detecting the object and the touchable device according to the embodiments can be used for detecting the object on the operation interface of the touchable device, thereby avoiding track jitters caused by the external environment. Moreover, through the method for detecting the object and the touchable device according to the embodiments, the output of the displacement amount corresponding to the movement of the object (that is, detected track information) can be controlled according to whether the object exists on the operation interface. 
         [0019]    For purposes of summarizing, some aspects, advantages and features of some embodiments of the invention have been described in this summary. Not necessarily all of (or any of) these summarized aspects, advantages or features will be embodied in any particular embodiment of the invention. Some of these summarized aspects, advantages and features and other aspects, advantages and features may become more fully apparent from the following detailed description and the appended claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]    The appended drawings contain figures of preferred embodiments to further clarify the above and other aspects, advantages and features of the disclosure. It will be appreciated that these drawings depict only preferred embodiments of the invention and are not intended to limits its scope. The invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which: 
           [0021]      FIG. 1  is a schematic structural view of a touchable device according to a first embodiment of the disclosure; 
           [0022]      FIG. 2A  is a schematic structural view of a touchable device according to a second embodiment of the disclosure; 
           [0023]      FIG. 2B  is a schematic structural view of a touchable device according to a third embodiment of the disclosure; 
           [0024]      FIG. 3  is a flow chart of a method for detecting an object according to a first embodiment of the disclosure; 
           [0025]      FIG. 4  is a flow chart of a method for detecting an object according to a second embodiment of the disclosure; 
           [0026]      FIG. 5  is a flow chart of a method for detecting an object according to a third embodiment of the disclosure; 
           [0027]      FIG. 6  is a flow chart of a method for detecting an object according to a fourth embodiment of the disclosure; 
           [0028]      FIG. 7  is a flow chart of a method for detecting an object according to a fifth embodiment of the disclosure; 
           [0029]      FIG. 8  is a flow chart of a method for detecting an object according to a sixth embodiment of the disclosure; and 
           [0030]      FIG. 9  is a flow chart of a method for detecting an object according to a seventh embodiment of the disclosure. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0031]    The detailed features and advantages of the disclosure are described below in great detail through the following embodiments, and the content of the detailed description is sufficient for those skilled in the art to understand the technical content of the disclosure and to implement the disclosure there accordingly. Based upon the content of the specification, the claims, and the drawings, those skilled in the art can easily understand the relevant objectives and advantages of the disclosure. The following embodiments are intended to describe the disclosure in further detail, but not intended to limit the scope of the disclosure in any way. 
         [0032]      FIG. 1  is a schematic structural view of a touchable device according to a first embodiment of the disclosure. 
         [0033]    Referring to  FIG. 1 , a touchable device  200  comprises an operation interface  210 , an image sensor  220 , and a processor  230 . The image sensor  220  is configured corresponding to the operation interface  210 , and the processor  230  is connected to the image sensor  220 . 
         [0034]    The image sensor  220  is used for acquiring an image on the operation interface  210 . The processor  230  determines whether an object having a fingerprint feature exists on the operation interface  210  by analyzing frequency components of the image acquired by the image sensor  220 . 
         [0035]    Here, the touchable device  200  detects whether the object exists and detect a movement track of the object using a single processor  230 . 
         [0036]    In other words, during normal operation, the processor  230  calculates a displacement amount of the object by using the image acquired by the image sensor  220 . 
         [0037]    Moreover, referring to  FIG. 2A , the touchable device  200  also detects whether the object exists with the processor  230 . Furthermore, a track detector is configured, for example, a displacement sensor  240  is connected to the processor  230 , and the touchable device  200  detects the movement track of the object with the displacement sensor  240 . 
         [0038]    That is to say, during normal operation, the displacement sensor  240  detects the movement track of the object through the image acquired by the image sensor  220  and generates a displacement amount corresponding to the movement track of the object. 
         [0039]    Here, the touchable device  200  detects whether the object exists by using the method for detecting the object. 
         [0040]    Referring to  FIG. 2B , a touchable device  200  comprises an operation interface  210 , a first image sensor  250 , a second image sensor  260 , and a processor  230 . The first image sensor  250  is configured corresponding to the operation interface  210 , and the processor  230  is connected to the first image sensor  250  and the second image sensor  260  respectively. In this embodiment, a track detector is the second image sensor  260 . 
         [0041]    The first image sensor  250  is used for acquiring an image on the operation interface  210 . The processor  230  determines whether a object having a fingerprint feature exists on the operation interface  210  by analyzing frequency components of the image acquired by the first image sensor  250 . The second image sensor  260  senses a movement track of the object according to the image acquired by the first image sensor  250 , and generates a corresponding control signal to the displacement processor  230  to generate a corresponding movement track. The second image sensor  260  obtains a corresponding image signal acquired by the first image sensor  250  through the connection to the first image sensor  250  or through the processor  230 . 
         [0042]    Referring to  FIG. 3 , first, the image sensor  220  of the touchable device  200  retrieves an image on the operation interface  210  (Step  110 ). Next, the acquired image is transferred to the processor  230 , so the processor  230  analyzes frequency components of the image. Here, the processor  230  converts the image acquired by the image sensor  220  into a signal in a frequency domain by using a frequency conversion function (Step  120 ), then analyzes the distribution at an MHF signal region for the signals in the frequency domain (Step  130 ), and generates a first signal or a second signal according to a distribution of the signals of the frequency domain (Step  140  or  150 ). 
         [0043]    The first signal indicates that the object exists on the operation interface  210 , and the second signal indicates that the object does not exist on the operation interface  210 . Here, the object may be a finger. The frequency conversion function may be a Discrete Fourier Transform (DFT) function, a Discrete Cosine Transform (DCT) function or a Discrete Wavelet Transform (DWT) function. 
         [0044]    Also, when the object does not exist on the operation interface  210 , the touchable device  200  does not output the displacement amount corresponding to the movement track of the object. In contrast, when the object exists on the operation interface  210 , the touchable device  200  outputs the displacement amount corresponding to the movement track of the object. 
         [0045]    In other words, referring to  FIG. 4 , when the object exists on the operation interface  210 , the processor  230  calculates the displacement amount of the object by using the image acquired by the image sensor  220  in response to the first signal, and outputs the calculated displacement amount to enable a cursor on a display (not shown) to move accordingly (Step  142 ). When the object does not exist on the operation interface  210 , the processor  230  does not calculate the displacement amount of the object in response to the second signal or does not output the calculated displacement amount, so the touchable device  200  does not output the displacement amount corresponding to the movement track of the object (Step  152 ). 
         [0046]    For the touchable device  200  that the displacement sensor  240  is used as the track detector, referring to  FIG. 5 , when the object exists on the operation interface  210 , the processor  230  enables the displacement sensor  240  to output the displacement amount corresponding to the movement track of the object according to the first signal (Step  144 ). When the object does not exist on the operation interface  210 , the processor  230  stops the operation of the displacement sensor  240  or interrupt the output of the displacement sensor  240  according to the second signal, so the touchable device  200  does not output the displacement amount corresponding to the movement track of the object (Step  152 ). For the touchable device  200  that the second image sensor  260  is used as the track detector, when the object exists on the operation interface  210 , the processor  230  uses the first signal to enable the second image sensor  260  to output the movement track of the object, and then calculates the displacement amount according to the movement track of the object. 
         [0047]    Here, the distribution of the signals in the MHF signal region can be determined by calculating energy or the number of the signals in the MHF signal region and comparing the calculated value with a preset threshold value. 
         [0048]    For the calculation of the energy of the signals in the MHF signal region, referring to  FIG. 6 , the processor  230  can calculate the energy of the signals located at the MHF signal region (Step  132 ) and compare the calculated energy of the signals with the preset threshold value (Step  134 ). When the energy of the signals is greater than the threshold value, the first signal is generated (Step  140 ), that is, the processor  230  determines that the object exists on the operation interface, so displacement detection corresponding to the image is performed normally. When the energy of the signals is not greater than the threshold value, the second signal is generated (Step  150 ), that is, the processor  230  determines that the object does not exist on the operation interface, so the displacement detection corresponding to the image is stopped or the output of the detected displacement amount is stopped. 
         [0049]    Referring to  FIG. 7 , in Step  132 , the signals of the frequency domain can be equally divided into N×N regions (Step  1321 ), wherein N is an integer greater than 1, and K×K regions within the scope of the N×N regions are defined, wherein K is a positive integer smaller than N. Then energy of the signals other than signals in K×K regions at an upper left corner in the N×N regions is calculated (Step  1322 ). In other words, in the N×N regions, the frequencies decrease from right to left and from bottom to top. 
         [0050]    For the calculation of the number of the signals in the MHF signal region, referring to  FIG. 8 , the processor  230  can calculate the number of the signals located at the MHF signal region (Step  136 ) and compare the calculated number of the signals with the preset threshold value (Step  138 ). When the number of the signals is greater than the threshold value, the first signal is generated (Step  140 ), that is, the processor  230  confirms that the object exists on the operation interface, so the displacement detection corresponding to the image is performed normally. When the number of the signals is not greater than the threshold value, the second signal is generated (Step  150 ), that is, the processor  230  confirms that the object does not exist on the operation interface, so the displacement detection corresponding to the image is stopped or the output of the detected displacement amount is stopped. 
         [0051]    Referring to  FIG. 9 , in Step  132 , the signals of the frequency domain can be equally divided into N×N regions (Step  1321 ), and then the number of the signals in all regions other than K×K regions at an upper left corner in the N x N regions is calculated (Step  1323 ). In other words, in the N×N regions, the frequencies decrease from right to left and from bottom to top. 
         [0052]    In conclusion, the method for detecting the object and the touchable device according to the embodiments can be used for detecting the object on the operation interface of the touchable device, thereby avoiding track jitters caused by the external environment. Moreover, through the method for detecting the object and the touchable device according to the disclosure, the output of the displacement amount corresponding to the movement of the object (that is, detected track information) can be controlled according to whether the object exists on the operation interface. 
         [0053]    The disclosure may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.