Abstract:
A physiological signals detection device has a light source connecting to a control unit, a light detector and a processing unit. The light detector has a pixel sensor array including multiple light sensing elements. The light source emits light through a lens to the human body to generate reflected light. The light detector receives the reflected light to generate a sensing signal. Since the light sensing elements respectively receive different reflected light from different directions, the light sensing elements receiving reflected light from the noise are easily selected and eliminated from calculating the physiology value. Therefore, the calculated physiology value is more accurate.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of United States provisional application filed on May 26, 2014 and having application Ser. No. 62/002,932, the entire contents of which are hereby incorporated herein by reference 
         [0002]    This application is based upon and claims priority under 35 U.S.C. 119 from Taiwan Patent Application No. 104111745 filed on Apr. 13, 2015, which is hereby specifically incorporated herein by this reference thereto. 
     
    
     BACKGROUND OF THE INVENTION 
       [0003]    1. Field of the Invention 
         [0004]    The present invention relates to a physiological signals detection device, especially to a physiological signals detection device using light detectors to detect human bodies&#39; physiological signals. 
         [0005]    2. Description of the Prior Arts 
         [0006]    With the progress of the technology, more and more functions can be achieved by the light detection. One of the functions is to detect human bodies&#39; physiological signals. Regarding heartbeat rate detection as an example, the heartbeat results in the flow of the blood to further result in the cyclical variation of the blood pressure. The pressure variation of the blood vessel changes the diameter of the blood vessel so that the cyclical variation of the blood pressure causes the diameter of the blood vessel to change continuously. Therefore, using the light detection result of the variation of the diameter of the blood vessel records the light variation of the reflected light from the light source emitting to the blood vessel to further calculate the heartbeat value. Other physiological values such as blood oxygen saturation index, blood pressure and so on can also be further calculated through obtaining the blood vessel signals or the blood signals via light detection. 
         [0007]    The conventional physiological signals detection device includes at least one light source and a light detector. The light source provides light beam emitted through the skin to the blood vessel and then results in a reflected light. The reflected light passes through the skin and is received by the light detector. The light detector converts the reflected light into a sensing signal. Then the processing unit calculates the desired physiological signal value based on the sensing signal. 
         [0008]    However, with referenced to  FIG. 5 , the light beam from the light source is also emitted to other objects on the path to the blood vessel, such as epidermal tissue. The light beam emitted to those other objects also results in reflected lights to be received by the light detector  60  together. Since the single light detector  60  receives the reflected lights from all directions, the reflected light resulting from the blood vessel and the reflected light resulting from those other objects are all received by the same light detector  60 . The light detector  60  can only converts the sum of the received reflected light into the sensing signal. Therefore, the sensing signal not only includes the information of the desired blood continuously variation value or the desired blood signal, but also includes other noises. Thus, the physiological signal value calculated by the processing unit based on the sensing signal is also not accurate. 
         [0009]    To overcome the shortcomings, the present invention provides a physiological signals detection device to mitigate or obviate the aforementioned problems. 
       SUMMARY OF THE INVENTION 
       [0010]    The main objective of the present invention is to provide a physiological signals detection device that excludes the noise from calculation to improve the accuracy of the physiological values. 
         [0011]    The physiological signals detection device comprising: 
         [0012]    a first light source providing a first light beam; 
         [0013]    a light detector having
       a pixel sensor array having multiple first light sensing elements and detecting a reflected light resulted from the first light beam emitted from the first light source to a user&#39;s body to generate a first sensing signal;       
 
         [0015]    a lens covering on the light detector, and the pixel sensor array receiving the reflected light of the first light beam through the lens; 
         [0016]    a processing unit connecting to the light detector and calculating the user&#39;s heartbeat value based on the first sensing signal; and 
         [0017]    a control unit connecting to the first light source, the light detector and the processing unit, switching the first light source on and off, controlling the light detector to sense and controlling the processing unit to process signals. 
         [0018]    The physiological signals detection device has following advantages. With the pixel sensor array, different light from different directions are received by different light sensing elements so that the control unit can determine whether the received signals are desired signals or a noises based on the intensity, frequency and so on of the received signals. Then the received signals from the light sensing elements that are determined as receiving noises are excluded. Only the received signals from the light sensing elements that are determined as receiving the desired signals are used to calculate the physiological value. Therefore, the noises are excluded from influencing the physiological value to enhance the accuracy of the physiological value. 
         [0019]    Other objectives, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]      FIG. 1  is an operational view of a physiological signals detection device in accordance with the present invention, shown a finger being placed on; 
           [0021]      FIG. 2  is a block diagram of a circuit of the physiological signals detection device in  FIG. 1 ; 
           [0022]      FIG. 3  is an illustrated view of a light detector of the physiological signals detection device in  FIG. 1 ; 
           [0023]      FIG. 4  is an illustrated view of a light path for receiving a reflected light by the physiological signals detection device in  FIG. 1 ; and 
           [0024]      FIG. 5  is an illustrated view of a light path for receiving a reflected light by a conventional physiological signals detection device in accordance with the prior art. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0025]    With reference to  FIGS. 1 and 2 , a physiological signals detection device in accordance with the present invention comprises a first light source  10 , a light detector  20 , a lens  30 , a processing unit  40  and a control unit  50 . 
         [0026]    The first light source  10  provides a first light beam. The first light beam may be infrared (IR) light. The physiological signals detection device further comprises a second light source  11  to provide a second light beam. The wavelength of the second light beam is different with the wavelength of the first light beam. The second light beam may be a green light. When the physiological signals detection device as described is applied to detect the heartbeat value or the blood pressure, the physiological signals detection device may only use a single light source such as the first light source  10  or the second light source  11 . When the physiological signals detection device as described is applied to detect the blood oxygen saturation index, the blood oxygen saturation index as described needs to use both the first and second light sources  10 ,  11  with different wavelength. 
         [0027]    The light detector  20  has a pixel sensor array  21  with multiple light sensing elements  211 . Each light sensing element  211  detects a reflected light resulting from the first light beam emitted to the user&#39;s body and generates a corresponding sensing signal. 
         [0028]    With reference to  FIG. 3 , in one embodiment, the pixel sensor array  21  may comprises M×N light sensing elements  211 . M and N are positive integer. The pixel sensor array  21  may be an active pixel sensor array. The light sensing elements  211  may comprises multiple first light sensing elements and multiple second sensing elements. The first light sensing elements are used to detect the reflected light of the first light beam. The second light sensing elements are used to detect the reflected light of the second light beam. In one embodiment, the light detector  20  further comprises a visible light sensor  22 , an IR sensor  23  and a black current sensor  24 . The visible light sensor  22  is mounted adjacent to the pixel sensor array  21  to perform ambient light sensing and/or color sensing. The black current sensor  24  is mounted adjacent to the pixel sensor array  21  to generate a reference signal for dark/black current compensation. The IR sensor  23  is mounted adjacent to the pixel sensor array  21  to perform proximity sensing, object position sensing, and/or gesture sensing. In one embodiment, the black current sensor  24  is mounted around the visible light sensor  22 , the IR sensor  23  is mounted around the black current sensor  24 . However, the arrangement is illustrated only and does not limit the present invention. For example, when the IR sensor  23  is mounted between the visible light sensor  22  and the pixel sensor array  21 , the functions of the pixel sensor array  21 , the visible light sensor  22 , the IR sensor  23  and the black current sensor  24  are not influenced. 
         [0029]    The lens  30  covers the light detector  20 . The light detector  20  senses light through the lens  30 . 
         [0030]    The processing unit  40  is connected to the light detector  20  to process the sensing signal of the light detector  20  and to further calculate the desired physiological signal such as the heartbeat value, the blood oxygen saturation index, the blood pressure and so on. In one embodiment, the processing unit  40  comprises, but is not limited to, a correlated double sampling circuit  41 , an amplifier  42 , an adder  43 , an analog-to-digital converter  44 , a black current compensation circuit  45 , a digital processing circuit  46  and a serial interface  47  (serial I/F such as two wire inter-integrated circuit). The signals out from the pixel sensor array  21  are processed by the correlated double sampling configuration with programmable gain settings consisted of the correlated double sampling circuit  41  and the amplifier  42 . The adder  43  adds the output of the amplifier  42  and the output of the black current compensation circuit  45  into an analog signal as an output of the adder  43 . Then the analog-to-digital converter  44  converts the analog signal to a digital signal as an output of the analog-to-digital converter  44 . The output of the black current compensation circuit  45  is generated based on the digital signal. The digital processing circuit  238  performs further operations upon the digital signal (e.g. the threshold comparison, the hysteresis detection and other detection algorithms), and transmits resulting data through the multiple contacts D [9:0], PCLK, HSYNC and VSYNC. The serial interface  47  is used for synchronous serial communication between the chips, and is coupled to a contact SCL corresponding to a serial clock line and a contact SDA corresponding to a serial data line. Since a person skilled in the art should understand the operations of each circuit element included in the processing unit  40 , no detailed discussion is further disclosed. 
         [0031]    The control unit  50  is connected to the first light source  10 , the second light source  11 , the light detector  20  and the processing unit  40 , The control unit  50  switches the first light source  10  and the second light source  11  on and off, controls the light detector  20  to sense, and controls the signal processing of the processing unit  40 . In one embodiment, the control unit  50  comprises, but is not limited to, a timing controller  51 , an IR LED driver  52 , a voltage regulator  53 , a clock generator  54 , a control register  55 , a power control circuit  56  and an interrupt circuit  57 . The timing controller  51  generates the control signal S_C 1  to control the IR LED driver  52 , and generates the control signal S_C 2  to control the pixel sensor array  21 . The IR LED driver  52  activates and deactivates the first light source  10  according to the control signal S_C 1 . The clock generator  54  receives an external clock such as a master clock from a contact MCLK. The power control circuit  56  receives a power control signal from a contact PWDN to control a power operation mode. The interrupt circuit  57  receives an interrupt signal from a contact INTB. Since a person skilled in the art should understand the operations of each circuit element included in the control unit  50 , no detailed discussion is further disclosed. 
         [0032]    In one embodiment, when the control unit  50  switches off the pixel sensor array  21 , the control unit  50  may switch on the visible light sensor  22  to perform ambient light sensing and/or color sensing. Similarly, when the control unit  50  switches off the pixel sensor array  21 , the control unit  50  may switch on the IR sensor  23  to perform proximity sensing, object position sensing, and/or gesture sensing. Therefore, when no physiological signals detection is needed, the pixel sensor array  21  may be switched off to save power but the visible light sensor  22  and the IR sensor  23  are still functioned to proceed detection with lower power consumption. Therefore, reducing power consumption is achieved. 
         [0033]    With reference to  FIGS. 1 and 2 , when the physiological signals detection device as described is used to detect heartbeat value, the user puts the corresponding part such as finger on the top of the lens  30 . The first light source  10  emits the first light to the finger to generate the reflected light, and then the reflected light pass through the lens  30  to be received by the light detector  20 . 
         [0034]    With reference to  FIGS. 2 and 4 , since the pixel sensor array  21  of the light detector  20  has multiple light sensing elements  211 , each light sensing element  211  receives a reflected light from one direction. Different light sensing elements  211  receive the reflected light from different direction. Each light sensing element  211  transmits the sensing signal to the processing unit  40 . The control unit  50  determines each received sensing signal is desired signal or noise based on the character of the reflected light, and controls the signal operation of the processing unit  40 . As to the light sensing elements  211  receive the desired signal, the processing unit  40  calculates the corresponding physiological value based on their sensing signals. As to the light sensing elements  211  receive the noises, the processing unit  40  ignores their sensing signals. 
         [0035]    Therefore, with the pixel sensor array  21  having multiple light sensing elements  211 , the light sensing elements  211  receiving the desired signals are distinguished from the light sensing elements  211  receiving the noises. Thus, the noises are easily excluded from the further calculation to allow the output physiological signals to be more precise. 
         [0036]    Even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and features of the invention, the disclosure is illustrative only. Changes may be made in the details, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.