Abstract:
A vessel sensing device with automatic amendment function includes an analog processing circuit, a signal generating circuit and a DC voltage detecting circuit. The analog processing circuit includes an optical sensing module. An optical sensor of the optical sensing module generates an analog signal with a skin characteristic signal and a vessel characteristic signal according to an optical reflecting signal. The skin characteristic signal and the vessel characteristic signal respectively correspond to a skin feature and a vessel feature of the user. The signal generating circuit is coupled to the analog processing circuit to transform the analog signal into a compensation signal. The DC voltage detecting circuit is coupled to the signal generating circuit and adapted to compensate the analog processing circuit according to the compensation signal, so as to decrease the skin characteristic signal within the analog signal.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a vessel sensing device, and more particularly, to a vessel sensing device with automatic amendment function by deducting color noise of the skin surface texture. 
         [0003]    2. Description of the Prior Art 
         [0004]    With the advanced technology, the wearable device has property of convenient portability and handy design, and the user can use the wearable device for physiological monitoring while in the gym or the ordinary life. The wearable device is worn on the skin of human body, such as the wrist. The wearable device monitors physical parameters and/or mental parameters by the biological feature sensor. The biological feature sensor can be a vessel sensor. The wearable device utilizes the vessel sensor to sense heart rhythm and breath rhythm of the user and display sensed information on the screen. However, the vessel is located under the skin texture, and precision of the conventional vessel sensor is decreased by skin color, skin roughness and/or fat thickness, so the conventional vessel sensor cannot effectively distinguish difference of the skin texture characteristic and the vessel characteristic cannot be accurately filtered for recognition. 
       SUMMARY OF THE INVENTION 
       [0005]    The present invention provides a vessel sensing device with automatic amendment function by deducting color noise of the skin surface texture for solving above drawbacks. 
         [0006]    According to the claimed invention, a vessel sensing device with automatic amendment function includes an analog processing circuit, a signal generating circuit and a direct current (DC) voltage detecting circuit. The analog processing circuit includes an optical sensing module, and an optical sensor of the optical sensing module generates an analog signal with a skin characteristic signal and a vessel characteristic signal according to an optical reflecting signal. The skin characteristic signal corresponds to a skin feature of an user, and the vessel characteristic signal corresponds to a vessel feature of the user. The signal generating circuit is electrically connected to the analog processing circuit and adapted to transform the analog signal into a compensation signal. The DC voltage detecting circuit is electrically connected to the signal generating circuit and adapted to compensate the analog processing circuit according to the compensation signal, so as to decrease the skin characteristic signal within the analog signal. 
         [0007]    According to the claimed invention, the optical sensing module further includes a switch electrically connected between the optical sensor and the signal generating circuit. The DC voltage detecting circuit controls signal quantity through the switch by varying gate voltage of the switch so as to compensate the analog processing circuit. 
         [0008]    According to the claimed invention, the optical sensing module further includes a switch and a charge capacity. The switch is electrically connected between the charge capacity, the optical sensor and the signal generating circuit. The DC voltage detecting circuit controls charging level of the charge capacity by varying gate voltage of the switch, so as to compensate the analog processing circuit. 
         [0009]    According to the claimed invention, the optical sensing module further includes a gain module electrically connected between the optical sensing module and the signal generating circuit. The DC voltage detecting circuit controls gain result of the gain module applied to the analog signal by varying a compensating voltage value of a compensation capacity of the gain module, so as to compensate the analog processing circuit. 
         [0010]    According to the claimed invention, the switch is an N-type Metal oxide semiconductor field effect transistor, a P-type Metal oxide semiconductor field effect transistor or a transmission gate. 
         [0011]    The vessel sensing device of the present invention can automatically deduct the redundant voltage resulted by the skin characteristic signal to accordingly increase the ratio of the vessel characteristic signal to the analog signal through the output port of the analog processing circuit while detecting the skin texture with different colors. The present invention utilizes the DC voltage detecting circuit to dynamically amend the analog processing circuit, the analog processing circuit outputs the analog signal wherefrom the skin characteristic signal is deducted, quantity of the analog signal can be enormously condensed to reduce calculation and transformation demands of electronic components of the vessel sensing device, and the vessel sensing device can have advantages of low power consumption, small-size mode and excellent sensory precision. 
         [0012]    These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1  is a diagram of a vessel sensing device according to a first embodiment of the present invention. 
           [0014]      FIG. 2  is a diagram of the vessel sensing device according to a second embodiment of the present invention. 
           [0015]      FIG. 3  is a diagram of the vessel sensing device according to a third embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0016]    Please refer to  FIG. 1 .  FIG. 1  is a diagram of a vessel sensing device  10  according to a first embodiment of the present invention. The vessel sensing device  10  includes an analog processing circuit  12 , a signal generating circuit  14  and a direct current (DC) voltage detecting circuit  16 . The vessel sensing device  10  is usually applied to the smart phone, the smart watch and any wearable device. The vessel sensing device  10  utilizes the analog processing circuit  12  to detect surface texture of the user so as to accordingly generate an analog signal by noninvasive optical sensing technology, and the analog signal contains a skin characteristic signal of the skin surface layer and a vessel characteristic signal of the skin sublayer. The skin characteristic signal corresponds to skin features of the user, such as skin color and/or roughness. The vessel characteristic signal corresponds to vessel features of the user, such as contractive variation of the vessel. That is, the skin characteristic signal within the analog signal is redundant noise for the vessel sensing device  10 . 
         [0017]    Different users provide different skin characteristic signal according to diversity of races and/or habits. For instance, a ratio of the skin characteristic signal of tanned skin to the analog signal is greater than a ratio of the skin characteristic signal of lightly pigmented skin to the analog signal. As the ratio of the skin characteristic signal to the analog signal obtained by the analog processing circuit  12  is greater than a threshold, the vessel sensing device  10  is difficult to recognize the vessel characteristic signal from the skin characteristic signal, and cannot provide proper heart rhythm information, sentiment index and/or pressure index for reference. Therefore, the vessel sensing device  10  utilizes the signal generating circuit  14  to transform the analog signal of the analog processing circuit  12  into a compensation signal. The DC voltage detecting circuit  16  can dynamically compensate the analog processing circuit  12  according to the compensation signal while being applied to the surface texture with different skin color, so as to reduce the skin characteristic signal within the analog signal to accordingly decrease interference of the vessel detecting result which may be affected by the skin color and/or roughness. 
         [0018]    In the first embodiment, the analog processing circuit  12  includes an optical sensing module  18  and a gain module  20 . The optical sensing module  18  receives an optical signal reflected from the skin to detect contraction of the vessel and to generate the corresponding analog signal by the noninvasive optical sensing technology, such as the photoplethysmogram technology. For example, the optical sensing module  18  includes an optical sensor  24 . A wavelength range of the optical signal conforms to a detective range of the optical sensor  24 . The optical signal preferably can be an invisible optical signal to prevent noise interference of environmental background. The optical signal is projected onto the surface texture of the user, and the optical sensor  24  can generate a photosensitive signal according to the optical reflecting signal formed by the optical signal reflected from the surface texture. The photosensitive signal contains parameters corresponding to the skin characteristic signal and the vessel characteristic signal of the skin texture. 
         [0019]    The gain module  20  is electrically connected between the optical sensing module  18  and the signal generating circuit  14  to enlarge the photosensitive signal detected by the optical sensing module  18 , and the corresponding analog signal is generated through an output port of the analog processing circuit  12 . The signal generating circuit  14  is electrically connected between the analog processing circuit  12  and the DC voltage detecting circuit  16 , to transform the analog signal from the analog processing circuit  12  into the compensation signal for the DC voltage detecting circuit  16 . The signal generating circuit  14  can be the analog to digital (A/D) converter which transforms the analog signal into the digital compensation signal. In order to decrease interference of the skin characteristic signal with the vessel detecting result, the optical sensing module  18  of the first embodiment includes a first switch  26  electrically connected between the optical sensor  24  and the signal generating circuit  14 . The vessel sensing device  10  utilizes the DC voltage detecting circuit  16  to dynamically compensate the gate voltage of the first switch  26 , so as to control photosensitive signal quantity through the first switch  26  by varying the gate voltage. For example, the DC voltage detecting circuit  16  can reduce the gate voltage of the first switch  26 , quantity of the photosensitive signal through the first switch  26  is decreased to accordingly deduct the direct current (DC) voltage value from the skin characteristic signal or to decrease a ratio of the DC voltage value to the skin characteristic signal. The vessel characteristic signal within the analog signal output by the analog processing circuit  12  can be fully reserved. 
         [0020]    Please refer to  FIG. 2 .  FIG. 2  is a diagram of the vessel sensing device  10 ′ according to a second embodiment of the present invention. In the second embodiment, elements having the same numeral as ones of the first embodiment have the same structures and functions, and a detailed description is omitted herein for simplicity. The optical sensing module  18 ′ of the vessel sensing device  10 ′ further includes a second switch  28  and a charge capacity  30 . The second switch  28  is electrically connected between the charge capacity  30 , the optical sensor  24  and the signal generating circuit  14 . The DC voltage detecting circuit  16  controls charging level of the charge capacity  30  by varying the gate voltage of the second switch  28  to dynamically compensate the analog processing circuit  12 . That is, the DC voltage detecting circuit  16  can activate the second switch  28  to charge the charge capacity  30 . Parts of the photosensitive signal may flow toward the charge capacity  30  via the second switch  28  while passing through the node A, which means the DC voltage value of the photosensitive signal corresponding to the skin characteristic signal can be deducted (or the ratio of the DC voltage value to the photosensitive signal can be decreased). Deduction of the DC voltage value from the photosensitive signal becomes greater since activating level of the second switch  28  becomes larger, and the analog signal through the output port of the analog processing circuit  12  can fully reserve the important vessel characteristic signal. 
         [0021]    Please refer to  FIG. 3 .  FIG. 3  is a diagram of the vessel sensing device  10 ″ according to a third embodiment of the present invention. In the third embodiment, elements having the same numerals as ones of the above-mentioned embodiments have the same structures and functions, and the detailed description is omitted herein for simplicity. The optical sensing module  18  of the vessel sensing device  10 ″ includes the optical sensor  24  which is grounded. The gain module  20 ′ enlarges the vessel characteristic signal and the skin characteristic signal of the analog signal simultaneously. In order to reduce the redundant skin characteristic signal within the analog signal, the gain module  20 ′ of the third embodiment includes a compensation capacity  32 , and the vessel sensing device  10 ″ utilizes the DC voltage detecting circuit  16  to adjust a compensating voltage value of the compensation capacity  32 , so as to control gain result of the gain module  20 ′ relative to the analog signal. During gain process of the analog signal, the skin characteristic signal is deducted by the compensation capacity  32  although the gain result of the skin characteristic signal and the vessel characteristic signal are similar, so the vessel sensing device  10 ″ can effectively prevent the vessel detecting result from being interfered by the skin characteristic signal by varying the gain result of the analog signal. 
         [0022]    In conclusion, the vessel sensing device of the present invention can automatically deduct the redundant voltage resulted by the skin characteristic signal to accordingly increase the ratio of the vessel characteristic signal to the analog signal through the output port of the analog processing circuit while detecting the skin texture with different colors. The DC voltage detecting circuit of the first embodiment utilizes the first switch electrically connected to the optical sensor to constrain the signal quantity through the first switch, so as to deduct the DC voltage value (which corresponds to the skin characteristic signal) from the photosensitive signal generated by the optical sensor. The DC voltage detecting circuit of the second embodiment utilizes the second switch electrically connected to the charge capacity to determine charge capacity of the charge capacity by adjusting the activating level of the second switch, so a to accordingly deduct the specific DC voltage value. The switches of the first embodiment and the second embodiment can be the N-type Metal oxide semiconductor field effect transistor (MOSFET), the P-type Metal oxide semiconductor field effect transistor (MOSFET) or the transmission gate. The DC voltage detecting circuit of the third embodiment controls the gain result of the gain module to deduct or decrease the skin characteristic signal within the analog signal. 
         [0023]    Therefore, the present invention utilizes the DC voltage detecting circuit to dynamically amend the analog processing circuit, the analog processing circuit outputs the analog signal wherefrom the skin characteristic signal is deducted, quantity of the analog signal can be enormously condensed to reduce calculation and transformation demands of electronic components of the vessel sensing device, and the vessel sensing device can have advantages of low power consumption, small-size mode and excellent sensory precision. 
         [0024]    Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.