Abstract:
The invention provides a biometric apparatus which is able to determine the orientation of a measured person irrespective of the orientation of the measured person on the biometric apparatus or irrespective of the orientation of arrangement of the biometric apparatus and hence flow an electric current constantly through the same route and measure the voltage generated in the route, thereby providing accurate and reliable biometric data. The invention provides a biometric apparatus includes a plurality of weight measuring units provided on a casing for allowing a measured person to get on the upper surface thereof; a comparative determination unit for comparing measured values measured by the weight measuring units respectively and determining the orientation of the body of the measured person on the casing on the basis of the result of comparison; and a biometric data acquiring unit for acquiring a biometric data of the measured person on the basis of the result of determination by the comparative determination unit.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a biometric apparatus and, more specifically, to a biometric apparatus provided with a biometric data acquiring unit. 
         [0003]    2. Description of the Related Art 
         [0004]    In recent years, various biometric apparatuses which are able not only to weigh the weight of a measured person but also to calculate other biometric data such as the percent body fat, the percent body moisture and so on have been proposed. Such biometric apparatuses generally include four electrode members arranged on a cover member which configures an upper surface of a casing. The electrode members include two sets of conducting electrode and measuring electrode. When the measured person places his/her one foot on one set of the conducting electrode and the measuring electrode, and the other foot on the other set of the conducting electrode and the measuring electrode, respectively, measurement of the biometric data is carried out simultaneously with measurement of the weight. With the biometric apparatus of this type, since an electric current is applied from the two conducting electrodes which come into contact with the toes of the both feet of the measured person and the voltage is detected by the two measuring electrodes which come into contact with the heels, the four electrode members are placed at predetermined positions on the upper surface of the casing (Japanese examined patent application publication 5-49050). 
         [0005]    However, with the biometric apparatus in the related art described above, there is a possibility to fail the accurate measurement when the measured person gets on the apparatus in an unexpected orientation. It is a case, for example, when an attempt is made to calculate the biometric data in a state in which the right foot is placed on the two conducting electrodes and the left foot is placed on the two measuring electrodes. In other words, although the measurement should be done by flowing the electric current between the tows of the both feet via both legs (lower body half) and measuring the voltage generated in this current route between the heels of the both feet, the current in this case flows between the toe and the heel of the right foot. Therefore, the voltage generated in this current route (right leg portion) cannot be measured between the toe and the heel of the left foot, and hence the bioimpedance cannot be measured. 
         [0006]    There is a case in which the front, rear, left and right are not apparent depending on the appearance design of the biometric apparatus, and hence the measured person is confused in the orientation to get on. In addition, in the case of the biometric apparatus in which a measuring portion having the electrode members and a display portion are separate, being able to get on the measuring portion freely in any orientations is expected. 
       SUMMARY OF THE INVENTION 
       [0007]    Accordingly it is an object of the invention to provide a biometric apparatus which is able to determine the orientation of a measured person irrespective of the orientation of the measured person on the biometric apparatus or irrespective of the orientation of arrangement of the biometric apparatus and hence flow an electric current constantly through the same route and measure the voltage generated in the route, thereby providing accurate and reliable biometric data. 
         [0008]    In order to solve the problems described above, the invention provides a biometric apparatus including a casing for allowing a measured person to get on the upper surface thereof; a plurality of weight measuring units provided in the casing; a comparative determination unit for comparing measured values measured by the weight measuring units respectively and determining the orientation of the body of the measured person on the casing on the basis of the result of comparison; and a biometric data acquiring unit for acquiring the biometric data of the measured person on the basis of the result of determination by the comparative determination unit. 
         [0009]    Preferably, the biometric data acquiring unit is a plurality of electrode members arranged on the upper surface of the casing, and includes a changeover unit for changing the function of the electrode members on the basis of the result of determination by the comparative determination unit. 
         [0010]    Preferably, the plurality of electrode members is at least a pair of electrode members, and the changeover unit inverts the setting to determine one of the pair of electrode members as a conducting electrode for applying an electric current to a foot of the measured person and determine the other electrode member as a measuring electrode for detecting the voltage from the foot of the measured person alternately on the basis of the result of determination by the comparative determination unit. 
         [0011]    Preferably, the comparative determination unit determines the side where a larger value is measured by the weight measuring unit to be the heel side of the measured person, and the changeover unit sets the electrode members provided on the side where the measured value is larger as the measuring electrode. 
         [0012]    Preferably, the plurality of weight measuring units include four weight measuring units. 
         [0013]    Preferably, the electrode members are provided at positions corresponding to the weight measuring units. 
         [0014]    Preferably, the comparative determination unit divides the four weight measuring units into two pairs, and determines that the heels of the measured person are positioned on the side of the two electrode members corresponding to the weight measuring units indicating the larger measured values in the respective pairs. 
         [0015]    Preferably, the weight measuring unit is a load cell. 
         [0016]    Preferably, the casing is formed of positioning members for positioning the positions of the foot of the measured person on the upper surface thereof outside the plurality of electrode members. 
         [0017]    Preferably, the electrode members have the same shape in plan view. 
         [0018]    According to the embodiment of the invention, the biometric apparatus includes the plurality of weight measuring units provided on the casing for allowing the measured person to get on the upper surface thereof, the comparative determination unit for comparing the measured values measured by the weight measuring units respectively and determining the orientation of the body of the measured person on the casing on the basis of the result of comparison, and the biometric data acquiring unit for acquiring the biometric data of the measured person on the basis of the result of determination by the comparative determination unit. Accordingly, there is provided a biometric apparatus which is able to determine the orientation of the measured person irrespective of the orientation of the measured person on the biometric apparatus or irrespective of the orientation of arrangement of the biometric apparatus and hence flow an electric current constantly through the same route and measure the voltage generated in the route, thereby providing accurate and reliable biometric data. Furthermore, since the shapes of the electrode members and the casing which have been designed to lead the measured person to get on in the right orientation are not limited any longer, the biometric apparatus may range in design. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]      FIG. 1  is an exploded perspective view sowing a configuration of a biometric apparatus according to an embodiment of the invention: 
           [0020]      FIG. 2  is a block diagram showing a control system relating to the weight measurement and the acquisition of a biometric data of the biometric apparatus according to the embodiment of the invention; and 
           [0021]      FIG. 3  is a flowchart showing a flow of the weight measurement and the acquisition of the biometric data using the biometric apparatus according to the embodiment of the invention. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0022]    Referring now to the drawings, an embodiment in which the invention is applied to a biometric apparatus  10  having four electrode panels  31 ,  32 ,  33 ,  34  on a cover member  20  and four load cells  61 ,  62 ,  63  and  64  will be described in detail.  FIG. 1  is an exploded perspective view showing a configuration of the biometric apparatus  10  according to the embodiment and  FIG. 2  is a block diagram showing a control system relating to the weight measurement and the acquisition of a biometric data of the biometric apparatus  10 . The invention may be applied to configuration other than that shown in the embodiment. 
         [0023]    As shown in  FIG. 1  and  FIG. 2 , the biometric apparatus  10  includes the cover member  20  and a bottom plate member  50  which constitute a casing, an electrode member  30  as a biometric data acquiring unit, a load cell  60  as a weight measuring unit, and a control circuit  12  as a comparative determination unit, and is adapted to be able to carry out the acquisition of the biometric data using the electrode member  30  and the weight measurement by the load cell  60  simultaneously. The biometric apparatus  10  is configured by placing a frame member  40  having the load cell  60  fixed thereto on the bottom plate member  50  and placing the cover member  20  holding the electrode member  30  thereon on the frame member  40 . The configuration of the each member will be described in detail. 
         [0024]    The cover member  20  is a substantially square plate-shaped member formed by molding with resin (for example, ABS resin (acrylonitril/butadiene/styrene copolymer)), and holds the electrode member  30  on an upper surface  20   a  thereof. The structure for holding the electrode member  30  may be selected as needed. For example, the electrode member  30  may be held by forming recesses (not shown) on the upper surface  20   a  of the cover member  20  for accommodating the electrode member  30  and fitting the electrode member  30  therein so as to be flush with the upper surface  20   a  (see  FIG. 1 ). In the embodiment, a display  21  and an operating unit  22  ( FIG. 2 ) are provided separately from the cover member  20 . However, these members may be provided integrally with the cover member  20 . 
         [0025]    As shown in  FIG. 2 , the display  21  and the operating unit  22  are connected to the control circuit  12 . A memory (for example, RAM (Random Access Memory))  14  is connected to the control circuit  12 , so that the measured person of the biometric apparatus  10  is able to enter his/her own personal data (for example, the height, the sex and the age) by operating the operating unit  22  and store the data in the memory  14 . The operating unit  22  is adapted to be able to read out the data from the memory  14  and display the data on the display  21 , to select one of measurement mode stored in the memory  14  in advance, and to display the results of measurement in sequence. 
         [0026]    The load cells  61 ,  62 ,  63  and  64  are connected to the control circuit  12  as the comparative determination unit via A/D converting circuits  81 ,  82 ,  83  and  84  and amplifiers  71 ,  72 ,  73  and  74  as amplifier circuits, respectively. The electrode panels  31 ,  32 ,  33  and  34  are also connected to the control circuit  12  via a current generating circuit  13  and a voltage detecting circuit  15 , and a selector (selector circuit)  16  as a changeover unit. 
         [0027]    The current generating circuit  13  is adapted to generate a constant current to be supplied from the electrode members set as the conducting electrodes to the toes of the measured person. The voltage detecting circuit  15  is adapted to acquire a potential (voltage) between both feet of the measured person generated by the electric current supplied from the current generating circuit  13  via the electrode members set as the measuring electrodes and detect the amount of voltage. The selector  16  is adapted to supply the electric current supplied from the current generating circuit  13  to the electrode members set as the conducting electrodes on the basis of the results of determination by the control circuit  12  as the comparative determination unit and connect the two electrode members set as the measuring electrodes to the voltage detecting circuit  15  for detecting the potential. 
         [0028]    The control circuit  12 , the current generating circuit  13 , the memory  14 , the voltage detecting circuit  15 , the amplifiers  71 ,  72 ,  73  and  74  and the A/D converting circuits  81 ,  82 ,  83  and  84  may be arranged at desired positions of the biometric apparatus  10 , for example, on the lower surface of the cover member  20  or the upper surface of the frame member  40 , although not shown in the drawings except for  FIG. 2 . 
         [0029]    The electrode member  30  includes four metallic electrode panels  31 ,  32 ,  33  and  34 . The four metallic electrode panels  31 ,  32 ,  33  and  34  preferably have the same shape and the same feature so as to be capable of applying an electric current to a living body (measured person) coming into contact therewith, or detecting the voltage. The electrode panels  31 ,  32 ,  33  and  34  are arranged at four corners of a substantially square planar shape of the cover member  20 . When the measured person places his/her toes and heels of both feet on the four electrode panels  31 ,  32 ,  33  and  34 , the measurement of the weight is started, and then acquisition of the biometric data is carried out. 
         [0030]    The cover member  20  is provided with projections  23 ,  24 ,  25  and  26  as positioning members on the plane of the upper surface  20   a  so as to project upward along two sides outside the electrode panels  31 ,  32 ,  33  and  34 , respectively. With the provision of the projections  23 ,  24 ,  25  and  26 , the correct placement of the toes and the heels of the measured person on the electrode panels  31 ,  32 ,  33  and  34  is ensured, whereby constant acquisition of the reliable and correct biometric data is ensured. The projections  23 ,  24 ,  25  and  26  may be arranged in an arbitrary shape, at arbitrary positions, and by an arbitrary number as long as they project upward at the electrode panels  31 ,  32 ,  33  and  34 . 
         [0031]    The frame member  40  is a plate-shaped member having a shape corresponding to the cover member  20 , and is formed of a high-strength material such as metal (aluminum, for example). Mounting recesses  41 ,  42 ,  43  and  44  as recesses for accommodating the load cell  60  are formed at four corners of the upper surface (the surface on the side of the cover member  20 ) of the frame member  40 , respectively. The mounting recesses  41 ,  42 ,  43  and  44  may be formed in the arbitrary shape at arbitrary positions of the frame member  40  corresponding to the configuration of the load cell  60 . The frame member  40  may be formed of a material other than the metal (ABS resin, for example) as long as sufficient strength is ensured in terms of the specification of the biometric apparatus  10 . 
         [0032]    The bottom plate member  50  is a plate-shaped metal (aluminum, for example) member provided with a flat shape corresponding to the cover member  20 , and constitutes the casing of the biometric apparatus  10  in association with the cover member  20 . The casing may be of a configuration other than the configuration composed of the cover member  20  and the bottom plate member  50  as the biometric apparatus  10  in the embodiment. 
         [0033]    The load cell  60  as the weight measuring unit includes load cells  61 ,  62 ,  63  and  64  to be accommodated in the mounting recesses  41 ,  42 ,  43  and  44  of the frame member  40 , which all have the same shape and feature. The load cells  61 ,  62 ,  63  and  64  are formed by providing strain measuring members  61   b ,  62   b ,  63   b  and  64   b  as strain gauges on metallic distortable members  61   a ,  62   a ,  63   a  and  64   a  which is distorted by being applied with a load respectively, and are arranged so as to be oriented toward the center of the planar shape of the frame member  40 , respectively. The load cells  61 ,  62 ,  63  and  64  are accommodated and fixed to the inside the mounting recesses  41 ,  42 ,  43  and  44  of the frame member  40  by screws  51 ,  52 ,  53  and  54 , respectively to constitute flexure beams. The strain measuring members  61   b ,  62   b ,  63   b  and  64   b  each includes, for example, a pair of strain gauges, which constitute a part of Wheatstone bridge, for understanding the expansion and contraction of the each strain measuring member of the load cells  61 ,  62 ,  63  and  64  caused by the weight of the measured person to be the change in value of electric resistance, whereby the weight of the measured person is calculated. The calculation is carried out by the control circuit  12 . 
         [0034]    Referring now to  FIG. 3 , a flow of the weight measurement and acquisition of the biometric data by the biometric apparatus  10  will be described.  FIG. 3  is a flowchart showing the flow of the weight measurement and the acquisition of the biometric data using the biometric apparatus  10 . 
         [0035]    The biometric apparatus  10  is activated when the measured person gets on the cover member  20  or operates the operating unit  22  (Step S 1 ), and the weight measurement starts when the measured person places his/her toes and heels of both feet on the electrode panels  31 ,  32 ,  33  and  34  (Step S 2 ). 
         [0036]    In the weight measurement, the values of resistance corresponding to the expansion or contraction of the strain measuring members of the load cells  61 ,  62 ,  63  and  64  caused on the basis of the loads applied thereto by the measured person getting on the cover member  20  are converted into voltage values via the Wheatstone bridge circuits, and the voltage values, after having amplified by the amplifiers  71 ,  72 ,  73  and  74  respectively, are digitized by the A/D converting circuits  81 ,  82 ,  83  and  84 , and are entered to the control circuit  12 , respectively. The control circuit  12  calculates the entered voltage values as the load values applied to the load cells  61 ,  62 ,  63  and  64  using a calculation program stored in advance in the memory  14 , respectively, and stores in the memory  14  in one-to-one correspondence with the load cells. The control circuit  12  calculates the weight of the measured person from the load values using the calculation program stored in advance in the memory  14 . 
         [0037]    On the other hand, the control circuit  12  compares the load values corresponding to the load cells  61 ,  62 ,  63  and  64  stored in the memory  14 , and determines the orientation of the measured person on the cover member  20  (Step S 3  to S 5 ). This determination is done by determining the side applied with a larger load from among the four sides of the plane of the cover member  20  as the portion where the heels of the measured person are placed. In other words, it is generally considered that when a person stands upright in a natural posture, the load (the weight) is applied more to the heels than to the toes. Therefore, it is determined that the heels of the measured person are placed on the two adjacent load cells (electrode panels) showing a larger value from among the load cells  61 ,  62 ,  63  and  64  (electrode panels  31 ,  32 ,  33  and  34 ), and the toes are placed on the remaining two adjacent load cells (electrode panels). For example, the comparison of the load values and the determination of the orientation of the measured person are carried out as follows. 
         [0038]    Firstly, the load values applied to the load cell  61  and the load cell  63  corresponding to the electrode panel  31  and the electrode panel  33  arranged at corners at opposite angles of the plane of the cover member  20  are compared (Step S 3 ). When the both load cells are the same (Yes in Step S 4 ), the weight measurement is carried out again to store new load values in the memory  14  (Step S 2 ). 
         [0039]    When the load values are not the same (No in Step S 4 ), the electrode panel corresponding to the larger load value is stored in the memory  14 , and then the load values at the load cell  62  and the load cell  64  corresponding to the electrode panel  32  and the electrode panel  34  arranged at different corners at opposite angles of the plane of the cover member  20  are compared (Step S 5 ). When the both load values are the same (YES in Step S 6 ), the weight measurement is carried out again to store new load values in the memory  14  (Step S 2 ). 
         [0040]    When the both load values are not the same (NO in Step S 6 ), the electrode panel corresponding to the larger load value is stored in the memory  14 . With the operation shown above, a pair of the electrode panels corresponding to a pair of the load cells showing the larger load values are stored in the memory  14 , and the control circuit  12  determines that the heels of the measured person are placed on the pair of stored adjacent electrode panels and the toes are placed on the remaining pair of adjacent electrode panels. Furthermore, when the electrode panels corresponding to the heels and the toes of the measured person, the arrangement of the both feet of the measured person on the cover member  20  is specified and hence the orientation of the body (the orientation of the feet) of the measured person is specified. The control circuit  12  sets the two electrode panels corresponding to the toes of the measured person as the conducting electrodes for applying the electric current and the two electrode panels corresponding to the heels as the measuring electrodes for detecting the voltage, respectively, and outputs the result of setting to the selector  16  (Step S 7 ). It is also possible to set the electrode panels on the toe side of the measured person as the measuring electrodes and the electrode panels on the heel side as the conducting electrodes. 
         [0041]    The selector  16  applies alternating current outputted from the current generating circuit  13  to the two electrode panels set as the conducting electrodes from among the electrode panels  31 ,  32 ,  33  and  34  (Step S 8 ), and starts measurement of the voltage value (potential difference) between the two electrode panels set as the measuring electrodes (Step S 9 ). 
         [0042]    The measurement of the voltage value is carried out by the voltage detecting circuit  15  connected to the measuring electrodes via the selector  16 . The measured voltage value is stored in the memory  14 , and the control circuit  12  calculates the bioimpedance (bioelectric impedance) between both feet of the measured person from the current value supplied from the conducting electrodes and the measured voltage value according to the program stored in the memory  14  in advance. The control circuit  12  is also able to calculate, for example, the percent body fat, the percent body moisture, the muscle mass, the basal metabolic rate, the bone mass, and the offal fat level as the biometric data from the weight calculated using the load cell  60  and the bioimpedance calculated using the electrode member  30  according to the program stored in the memory  14  in advance (Step S 10 ). The calculated weight and the biometric data are displayed on the display  21  and the entire measurement process is ended (Step S 11 ). 
         [0043]    Modifications will be described below. In the flow of biometric data acquisition described above, the load values at the load cells at the corners at opposite angles are compared, the electrode panels corresponding to the load cells which show the larger load values are determined to be under the heels of the measured person, and then these electrode panels are set as the conducting electrodes. However, it is also possible to employ a comparative determination method instead, which includes steps of comparing the load values of all the load cells and setting the electrode panels corresponding to the load cells showing the larger two load values as the conducting electrodes. 
         [0044]    Alternatively, it is also possible to employ two electrode panels instead of the four electrode panels  31 ,  32 ,  33  and  34  described above. In this case, both of these two electrode panels are provided with functions of the conducting panel and the measuring panel, so that when conducting from one electrode panel to the other electrode panel in a state in which the left foot of the measured person is placed on one of these electrode panels and the right foot of the measured person on the other electrode panel, the bioelectric impedance is obtained on the basis of the result of measurement of the voltage between the both electrode panels. In this configuration, when the toe and the heel of the same foot is placed on the both electrode panels, the current route via the legs (lower body half) of the measured person is not formed, and hence the accurate bioimpedance cannot be calculated. Therefore, the invention is applied to this configuration, so that whether the measured person is on the electrode panels in the orientation which enables measurement of the bioimpedance or not can be determined. The invention is also applicable to the biometric apparatus provided with a height measuring apparatus of a type which measures the height of the measured person by bringing a measuring terminal which is movable in the vertical direction into contact with the parietal region of the measured person, and the case in which two electrode panels are provided as in the case shown above is preferable in that determination of the orientation of the measured person between the posture with his/her front side toward the height measuring apparatus and the posture with his/her back toward the height measuring apparatus is easily made. 
         [0045]    It is preferable to arrange the load cells one each at four corners of the frame member  40  as described above from the view point of determining the orientation of the measured person accurately. However, determination of the orientation of the measured person on the cover member  20  is achieved with at least two load cells with a simple and cost effective configuration. 
         [0046]    It is also possible to configure the electrode panels in a mode other than the four metallic electrode panels. For example, it is also possible to provide a plurality of reference resistances having known different values of resistance in the control circuit  12  in series or in parallel to the body of the measured person, acquire the potential generated because of the respective reference resistances in association with the potential generated between the feet, and calculate the bioimpedance of the measured person on the basis of the ratio between the respective acquired potentials and the values of resistance of the reference resistances. In this case, a configuration with the two metallic electrode panels is applicable. In this configuration, even when the current value supplied to the body is unknown, the bioimpedance data can be obtained. 
         [0047]    In the embodiment shown above, the current generating circuit  13  and the voltage detecting circuit  15  are selectively connected to the conducting electrodes and the measuring electrodes using the selector  16 . Alternatively, it is also possible to arrange, for example, a rotatable electrode switching member in a plane parallel to the cover member  20  in the casing, and connect the current generating circuit  13  to the electrode panel to be set as the conducting electrode and the voltage detecting circuit  15  to the electrode panel to be set as the measuring electrode, respectively. 
         [0048]    In the embodiment shown above, a set of the current generating circuit  13  and the voltage detecting circuit  15  is selectively connected to the four electrode panels using the selector  16 . Alternatively, it is also possible to connect the set of the current generating circuit and the voltage detecting circuit to each of the four electrode panels and instruct which one of the current generating circuit and the voltage detecting circuit for the respective electrode panels are to be used according to the results of determination by the control circuit  12 .