Abstract:
A portable body fat measurement device includes: a light source unit having at least two top view light sources and a guide unit perpendicularly guiding an optical signal generated in the top view light sources to determine a measurement point where body fat is measured; an optical detection unit detecting a scattered optical signal to transform into an electrical signal, the scattered optical signal being generated by a scattering of the optical signal irradiated to the measurement point; and a signal processing unit processing the electrical signal and calculating body fat information, wherein the at least two top view light sources and the optical detection unit are horizontally arranged.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of Korean Patent Application No. 10-2006-0039638, filed on May 2, 2006, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference. 
       BACKGROUND 
       [0002]    1. Field 
         [0003]    The present invention relates to a portable body fat measurement device having a top-view light source and an optical sensor module of the portable body fat measurement device, and more particularly to a portable body fat measurement device which enters a light outputted from a top view light source in a measurement point and calculates body fat information by using a scattered light scattered from the measurement point, and an optical sensor module of the portable body fat measurement device. 
         [0004]    2. Description of the Related Art 
         [0005]    Health and beauty are critical issues for people living in modern society, accordingly a well-being trend seeking a healthy and enjoyable life is currently booming. One criterion for health estimation is measuring an obesity rate. There are various methods of measuring the obesity rate, and a body fat ratio is usually one of the criteria for measuring the obesity rate. Also, the body fat ratio may be one criterion for people on a diet for beauty purposes. 
         [0006]    The methods of measuring a body fat ratio consists of a body average density measurement measuring weight in the water, a skinfold test calculating the body fat ratio by measurement thickness of fat in a specific point of a body, a body impedance analysis calculating the body fat ratio by measuring a resistance in a body by flowing a weak current in the body, a weight and waist relation table measuring the body fat ratio by using a weight and a waist size, and the like. However these methods need mostly complicated equipment and are inaccurate when measuring the body fat ratio. 
         [0007]    Currently, a body fat measurement method using a light capable of readily and accurately measuring body fat, is disclosed. A body fat measurement device using the light is based on a theory that when a light emitted from a light source is irradiated at a measurement point of a body, backward-scattering occurs in the body, and subsequently, a body fat is measured by measuring a scattered optical signal using an optical detector. The body fat measurement device using the light has a defect in that the light source is generally too large to be adopted into a portable device, and when the device is miniaturized, accuracy of the body fat measurement device may not be guaranteed since the accuracy of the body fat measurement device depends on a light irradiated dimension and an optical volume. Accordingly, there is a need for a portable body fat measurement device which readily and accurately measures thickness of body fat for a user. 
       SUMMARY 
       [0008]    Additional aspects and/or advantages will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the invention. 
         [0009]    In an aspect of the present invention, a portable body fat measurement device and an optical sensor module in the device which may be installed in a portable terminal, e.g. a mobile communication terminal, are provided in which a thickness of the optical sensor module is minimized since a top view light source type light of a surface mount is used as the optical sensor module. 
         [0010]    In an aspect of the present invention, a portable body fat measurement device and an optical sensor module in the device are provided in which a thickness of the optical sensor module is minimized and a sufficient optical volume for measuring a thickness of a body fat is enabled since the optical sensor module is configured by horizontally arranging at least two light sources and an optical detection unit. 
         [0011]    In an aspect of the present invention, a portable body fat measurement device and an optical sensor module in the device are also provided which minimize a decrease of optical power since an irradiation angle of a light outputted from a top view light source is limited via a guide unit, e.g., a prism sheet and the like, so that the light is perpendicularly irradiated in a measurement point. 
         [0012]    In an aspect of the present invention, a portable body fat measurement device and an optical sensor module in the device are provided which minimize a measurement error of a thickness of body fat, which is caused by absorption of a scattered light by hemoglobin (Hb), by outputting a message requesting a change of a measurement point when an optical detection unit receiving a scattered light backscattered from the measurement point is above a blood vessel. 
         [0013]    According to an aspect of the present invention, there is provided a portable body fat measurement device that includes: a light source unit having at least two top view light sources and a guide unit perpendicularly guiding an optical signal generated in the top view light sources for a measurement point where body fat is measured; an optical detection unit detecting a scattered optical signal to transform into an electrical signal, the scattered optical signal being generated by a scattering of the optical signal irradiated to the measurement point; and a signal processing unit processing the electrical signal and calculating body fat information, wherein the at least two top view light sources and the optical detection unit are horizontally arranged. 
         [0014]    According to another aspect of the present invention, there is provided an optical sensor module included in a body fat measurement device, wherein the module includes: a light source unit having at least two top view light sources and a guide unit perpendicularly guiding an optical signal generated in the top view light sources for a measurement point where body fat is measured; an optical detection unit detecting a scattered optical signal to transform into an electrical signal, wherein the at least two top view light source and the optical detection unit are horizontally arranged, the electrical signal is supplied to a predetermined signal processing unit, and the signal processing unit receives the electrical signal to calculate body fat information in the measurement point. 
         [0015]    In an aspect of the present invention, the mobile terminal may be one of a personal digital assistant (PDA), a portable game device, an MP3 player, a personal multimedia player (PMP), a Digital Multimedia broadcasting (DMB) terminal, or a notebook. 
         [0016]    In an aspect of the present invention, optical detection unit of the portable body fat measurement device includes an optical-electrical transducing element transforming an optical signal into an electrical signal. 
         [0017]    In an aspect of the present invention, the optical detection unit of the optical sensor module includes an optical-electrical transducing element transforming an optical signal into an electrical signal. 
         [0018]    In an aspect of the present invention, in the optical sensor module, at least one light source unit outputs an optical signal having a wavelength between approximately 600 and 800 nm. 
         [0019]    In an aspect of the present invention, in the portable body fat measurement device, at least one light source unit outputs a light having a wavelength between approximately 600 and 950 nm. 
         [0020]    In an aspect of the present invention, in the optical sensor module, at least one light source unit outputs an optical signal having a wavelength between approximately 600 and 950 nm. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]    These and/or other aspects and advantages will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which: 
           [0022]      FIG. 1  is a block diagram illustrating a configuration of a portable body fat measurement device according to an embodiment of the present invention; 
           [0023]      FIG. 2(   a ) is a diagram illustrating a top view of an optical sensor module in a portable body fat measurement device according to an embodiment of the present invention, and  FIG. 2(   b ) is a diagram illustrating a structure and a shape of the top view light sources and the guide unit in accordance with an embodiment of the present invention; 
           [0024]      FIG. 3  is a diagram illustrating a side view of an optical sensor module in a portable body fat measurement device according to an embodiment of the present invention; 
           [0025]      FIG. 4  illustrates histograms showing a volume of operation current of an optical sensor module and a volume of a scattered light scattered from a measurement point according to an embodiment of the present invention; and 
           [0026]      FIG. 5  is a diagram illustrating a decrease of absorption for each wavelength of a hemoglobin (Hb) component in blood according to an embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0027]    Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The embodiments are described below to explain the present invention by referring to the figures. 
         [0028]    A portable body fat measurement device may include one of a mobile terminal, e.g., a personal digital assistant (PDA), a portable game device, an MP3 player, a personal multimedia player (PMP), a Digital Multimedia broadcasting (DMB) terminal, and a notebook. Namely, the portable body fat measurement device may be embodied as an optical sensor module, according to an embodiment of the present invention, that is included as one configuration of the mobile terminal. Also, the portable body fat measurement device may not be installed in the mobile terminal, but rather may be designed to have an independent configuration from the mobile terminal. 
         [0029]    Also, a measurement point  114  used in the current invention includes a human body and a bioprosthetic tissue having a similar property with respect to a property of the human body. The portable body fat measurement device and the optical sensor module in the device may be used for measuring a thickness of body fat included in the human body and in the bioprosthetic tissue. 
         [0030]      FIG. 1 , numeral  100 , is a block diagram illustrating a configuration of a portable body fat measurement device according to an embodiment of the present invention. 
         [0031]    The portable body fat measurement device according to the present invention includes an optical sensor module  110 , a signal processing unit  120  and an output unit  130 . The optical sensor module  110  includes an optical volume control unit  111 , a light source unit  112  and an optical detection unit  113 . The signal processing unit  120  includes a signal amplification unit  121 , a body fat information unit  122  and an output control unit  123 . The output unit  130  includes a display unit  131  and a sound output unit  132 . 
         [0032]    The light source unit  112  of the optical sensor module  110  includes a guide unit  211  perpendicularly guiding at least two top view light sources outputting a light having a predetermined dimension and a light irradiated from the two top view light sources. 
         [0033]    The top view light sources may be one of a point light source or a surface light source, and the point light source or the surface light source includes a light emitting diode (LED). The guide unit  211  guides the light irradiated from the two top view light sources to be perpendicularly irradiated to a measurement point  114 , and the guide unit  211  may be a prism sheet. A structure and a shape of the top view light sources and the guide unit  211  will be described in detail by referring to  FIG. 2(   b ). 
         [0034]      FIG. 2(   a ) is a diagram illustrating a top-view of an optical sensor module in a portable body fat measurement device according to an embodiment of the present invention. 
         [0035]    In  FIG. 2(   a ), a top view of the optical detection unit  210  of the optical sensor module  110  and the light source unit  112  are illustrated. Depending upon the embodiment of the present invention, with respect to the light source unit  112 , at least two light source units may be utilized for measuring the thickness of body fat, and at least three light source units may be utilized for comparatively more accurate measurement. As a number of the light source units increases, a reference of a scattered light that may be used for the measurement of the body fat for the measurement point  114  increases, and therefore, accuracy of a measurement result may be improved. 
         [0036]    Examples of three light source units S 1 , S 2  and S 3  are illustrated in  FIG. 2(   a ). 
         [0037]    The at least two light source units  212  and a optical detection unit  210  are horizontally arranged, such as are illustrated in  FIG. 2(   a ), and each of the light source units S 1 , S 2 , and S 3  is horizontally arranged apart from the optical detection unit  210  by spaced distances SD 1 , SD 2  and SD 3 , respectively. 
         [0038]    The light source units S 1 , S 2 , and S 3  include a top view light source  212  and a guide unit  211 . At least one top view light source  212  may be established in each of the light source units S 1 , S 2 , and S 3 , such as are illustrated in  FIG. 2(   a ), and each of the light source units S 1 , S 2 , and S 3  are horizontally arranged with respect to the optical detection unit  210  and include at least one top view light source  212 . A number and a location of the top view light source  212  may be variously embodied by those skilled in the art. The top view light source  212  may be one of a point light source or a surface light source, both of which may include an LED. 
         [0039]    The guide unit  211  perpendicularly guides the light irradiated from the top view light sources to be irradiated toward a measurement point  114 . Since a general top-view LED has a large radiation angle, an intensity of a light which is outputted to a perpendicular direction tends to decrease. Therefore, the guide unit  211  may minimize the decrease of the light by reducing the radiation angle of the light from the top view LED and guiding the light in the measurement point  114  in a perpendicular direction. For the above operation, the guide unit  211  may include a prism sheet. Also, the guide unit  211  may include various units used in the art, including the prism sheet. 
         [0040]    As described above, the light from the top view light source  212  is perpendicularly irradiated in the measurement point  114  via the guide unit  211 . In this case, the light is irradiated via an entire top surface of the guide unit  211 , i.e., the light is irradiated in a type of a surface light, and the irradiated light is may be as large as a dimension of the top surface of the guide unit  211 . 
         [0041]    Each of the light source units S 1 , S 2 , and S 3 , including the top view light source  212  and guide unit  211 , is spaced apart from the optical detection unit  210  by a predetermined distance, i.e., the light source S 1  is spaced apart from the optical detection unit  210  by a spaced distance SD 1 , the light source S 2  is spaced apart from the optical detection unit  210  by a spaced distance SD 2 , and the light source S 3  is spaced apart from the optical detection unit  210  by a spaced distance SD 3 . The spaced distances SD 1 , SD 2 , and SD 3  may be variously established according to a threshold of the thickness of the body fat measurable in the measurement point  114 . Namely, when values of the spaced distances SD 1 , SD 2 , and SD 3  are increased, the threshold of the thickness of the body fat that is measurable in the measurement point  114  comparatively increases. 
         [0042]    Also, optical volumes outputted from each of the top view light sources  212  of each of the light source units may increase according to the spaced distances from the optical detection unit  210 . Namely, the optical volumes may increase in an order of an optical volume outputted from the top light sources  212  of the spaced distances S 1 , S 2 , and S 3 , and the optical volumes may be controlled by the optical volume control unit  111 . Wavelengths of the lights from each of the top view light sources  212  may be identical to each other. 
         [0043]    Also, the light source units  112  to be installed in a mobile terminal, including the top view light sources  212  and the guide units  211 , may have a thickness of less than approximately 1.5 mm. As described above, a slimmer light source unit may be embodied by establishing at least two top view light sources in an array type to the guide unit  211 . Accordingly, the optical sensor module  110  to be installed in the mobile terminal according to an embodiment of the present invention may be optimized, where a thickness is extremely limited due to a location of components within the mobile terminal. 
         [0044]    Also, a slimmer, but comparatively greater surface light source may be embodied by arranging each of the top view light sources  212  in an array type in the guide units  211 , regardless of thickness or a size of the mobile terminal. 
         [0045]    Again referring to  FIG. 1 , the optical volume control  111  unit controls operational current supplied to the at least two top view light sources. As described above, the operation current may be controlled by optical volumes outputted from each of the top view light sources and may increase in proportion to the spaced distances from the optical detection unit  113 . 
         [0046]    The optical detection unit  113  receives at least two scattered lights from the measurement point  114  and transforms the received lights into an electrical signal. Namely, the optical detection unit  113  receives a light, irradiated from the light source unit  112  into the measurement point  114  and scattered from the measurement point  114 , and transforms the received light into the electrical signal. For the above operation, the optical detection unit  113  may include an optical-electrical transducing element transforming an optical signal into an electrical signal. 
         [0047]    The signal processing unit  120  receives the electrical signal and calculates a thickness of body fat in the measurement point  114 . For the above operation, the signal processing unit  120  includes a signal amplification unit  121 , a body fat information unit  122 , and an output control unit  123   
         [0048]    The signal amplification unit  121  transmits the received electrical signal to the body fat information unit  122  after amplifying the electrical signal which has been transformed in the optical detection unit  113 . 
         [0049]    The body fat information unit  122  calculates the thickness of the body fat in the measurement point  114  according to the amplified electrical signal. The body fat information unit  122  may calculate the thickness of the body fat from a strength of a scattered light, irradiated from the optical detection unit  112  and absorbed or scattered at the measurement point  114 , and also calculates a body fat ratio as a percentage, or weight of the body fat via a reference lookup table. The above operation will be described below. 
         [0050]      FIG. 3  is a diagram illustrating a lateral face of an optical sensor module in a portable body fat measurement device according to an embodiment of the present invention. Each of the light source units S 1 , S 2 , and S 3   212  is horizontally arranged apart from the optical detection unit D  210  by spaced distances and supply light that is scattered by skin  213 , fat  214  and muscle  215  and inputted to the detection unit D  210 . 
         [0051]      FIG. 4  illustrates histograms showing a relative volume of operation current of an optical sensor module and a relative volume of a scattered light scattered from a measurement point  114  according to an embodiment of the present invention. 
         [0052]    As described in  FIG. 2(   a ), each of the light source units S 1 , S 2 , and S 3  is horizontally arranged apart from the optical detection unit D  210  by spaced distances SD 1 , SD 2 , and SD 3 . An optical volume control unit  111  may control the operation current supplied to each of the light source units S 1 , S 2  and S 3 , as optical volumes become greater in an order of spaced distances from the optical detection unit D, i.e., an optical volume supplied to the light source unit S 1  is greater than an optical volume supplied to the light source unit S 2 , and the optical volume supplied to the light source unit S 2  is greater than an optical volume supplied to the light source unit S 3 . 
         [0053]    In this case, as illustrated in  FIG. 4 , a volume of a scattered light, irradiated from the light source unit S 1 , scattered from the measurement point  114  and inputted to the detection unit D  210  is less than a scattered light corresponding to the light source unit S 2 , and a volume of the scattered light corresponding to the light source unit S 2  is less than a scattered light corresponding to a light source unit S 3 . 
         [0054]    Referring back to  FIG. 1 , an output control unit  123  controls the body fat information to be displayed or played via the output unit  130 . The output unit  130  may display or play the body fat information via a display unit  131  or a sound output unit  132 . 
         [0055]    In this case, when the electrical signal transformed by the signal amplification unit  121  is less than a predetermined value, the output control unit  123  controls a message requesting a user to change a measurement point  114  to be displayed and/or played via the output unit  130 . Specifically, when the body fat information calculation unit  122  is not able to calculate thickness of body fat since the electrical signal is weak, the output control unit  123  provides the user with the message requesting a change of the measurement point  114  via the output unit  130 . 
         [0056]    Referring to  FIG. 1 , when a blood vessel (not shown) is located at the measurement point  114 , the electrical signal is weak. Blood flowing through the blood vessel (not shown) includes hemoglobin (Hb). The Hb has a property that causes absorption of the scattered light irradiated to the optical detection unit  113 , i.e., since the Hb absorbs the scattered light, a volume of the scattered light irradiated to the optical detection unit  113  decreases, and in this case, the body fat may not be accurately measured. 
         [0057]    Accordingly, when a volume of the electrical signal is less than the predetermined value, the output control unit  123  may provide the user with a message requesting a change of the measurement point  114 . The message may be displayed in a display unit  131  in a type of a short message service (SMS) or played via the output unit  132  that utilizes an alerting sound or a speech message. 
         [0058]    According to another embodiment of the present invention, in order to detect a case that the scattered light is absorbed in the Hb, at least one of the at least two top view light sources side-view light sources may output a light having a wavelength of approximately 600 through 800 nms, which has a comparatively greater absorption for the Hb. 
         [0059]      FIG. 5  is a diagram illustrating a decrease of absorption for each wavelength of a Hb component in blood according to an embodiment of the present invention. 
         [0060]    As illustrated in  FIG. 5 , absorption by the Hb for a wavelength between approximately 600 and 800 nm is highest. A guide unit  421  guides light that is irradiated from the light source units S 1 , S 2  and S 3   422 . Accordingly, a case that an optical detection unit D  410  is located above a blood vessel is more accurately detected when at least one of the at least two light sources irradiates the light having the wavelength of approximately 600 through 800 nm, and subsequently a user is able to request a change of the measurement point  114 . Namely, according to an embodiment of the present invention, a plurality of light sources may irradiate a light having a wavelength between approximately 600 and 950 nm, and more specifically, at least one of the plurality of light sources may irradiate a light having a wavelength between approximately 600 and 800 nm. 
         [0061]    Accordingly to another embodiment of the present invention, a measurement error of thickness of body fat may be minimized since the portable body fat measurement device  100  is not located above the blood vessel of the user. 
         [0062]    According to the present invention, there is provided a portable body fat measurement device and an optical sensor module in the device which may be installed in a portable terminal, e.g., a mobile communication terminal, by minimizing a thickness of the optical sensor module since a top view light source type light of a surface mount is used as the optical sensor module. 
         [0063]    According to the present invention, there is provided a portable body fat measurement device and an optical sensor module in the device which minimize a thickness of the optical sensor module and enable sufficient optical volume for measuring a thickness of body fat since the optical sensor module is configured by horizontally arranging at least two light sources and an optical detection unit. 
         [0064]    According to the present invention, there is provided a portable body fat measurement device and an optical sensor module in the device which minimize a decrease of optical power since an irradiation angle of a light outputted from a top view light source is limited via a guide unit, e.g., a prism sheet and the like, so that the light is perpendicularly irradiated in a measurement point. 
         [0065]    According to the present invention, there is provided a portable body fat measurement device and an optical sensor module in the device which minimize a measurement error of a thickness of body fat which is caused by absorption of a scattered light by hemoglobin (Hb) by outputting a message requesting a change in a measurement point when an optical detection unit receiving a scattered light backscattered from the measurement point is above a blood vessel. 
         [0066]    Although a few embodiments have been shown and described, it would be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.