WO2003077753A1

WO2003077753A1 - Body fat measuring equipment

Info

Publication number: WO2003077753A1
Application number: PCT/KR2003/000526
Authority: WO
Inventors: Dong-Man Kim
Original assignee: Dong-Man Kim
Priority date: 2002-03-18
Filing date: 2003-03-18
Publication date: 2003-09-25
Also published as: AU2003217516A1

Abstract

The present invention relates to a body fat measuring equipment using a bioelectric impedance analysis. The present invention provides a body fat measuring equipment, using a bioelectric impedancce analysis, comprising: a current supply circuit; a voltage detection circuit; a conductive electrode plate contacted with a portion of the human body for measuring a impedance of the human body; a microprocessor for calculating body fat based on the measured impedance; an A/D converting circuit for converting a voltage signal detected by the voltage detection circuit into a digital signal and transmitting the digital signal to the microprocessor; data input means for inputting personal information of weight, tallness, sex and so on; and an image display device for display the measured results, wherein the current supply circuit comprises a constant current generating circuit for supplying a constant current to the human body, an alternating current generating circuit for generating a alternating current in a sinusoidal wave form, and a signal mixing circuit for mixing the generated constant current and alternating current and converting the constant current into an alternating current, thereby generating a signal having the sinusoidal wave form to measure the impedance of the human body; and wherein the voltage detection circuit comprises a voltage follower circuit.

Description

BODY FAT MEASURING EQUIPMENT

TECHNICAL FIELD

The present invention relates to a body fat measuring equipment using bioelectric impedance analysis (BIA).

Medically, 'fatness ' of a human body is determined with not overweight, but fat ratio of the human body.

There have been known various methods of measuring body fat ratio of the human body. The methods include a standard weigh method, a human body mass index method, a under-water the human body density method, a skin wrinkle thickness method, a moisture content in the human body, and so on. Nowadays, the most reliable method is a bioelectric impedance analysis.

BACKGROUND ART

The bioelectric impedance analysis was suggested by Hoffer, in 1998. He reported that moisture content in the human body is inversely proportional to electric resistance of the human body. Since 1980, many doctors, nutritionists, physical exercise researcher, and so on have developed the analysis. Nowadays, the reliability of the bioelectric impedance analysis has been generally accepted in the related fields.

The bioelectric impedance analysis is a technique for measuring the moisture content in the human body with electrical processes. In the analysis, a weak alternating current is applied to the human body, and then a alternating current passes through the moisture in the human body. The current flows to form a current path, of which cross sectional area is measured as a impedance.

In the bioelectric impedance analysis, the impedance between portions of outside of the human body and electrodes to be in contact with the same is measured. Therefore the bioelectric impedance analysis has some advantages of easily measuring body fat with a high accuracy while the user is easy to access them.

The human body is typically composed of moisture, proteins, fat, and minerals. Muscle of the human body is mainly composed of proteins and moisture. The proteins content are proportional to moisture content. It is noted that the muscle of a health person has about 73% of proteins and about 27% of moisture. Also, the minerals mainly constitute bone structure of the human body. It is noted that the weight of bone structure is closely associated with a quantity of muscle in the average human body.

The current can not pass through fat but through moisture, described above. Therefore, the moisture content in the human body can be evaluated by measuring the impedance. And also, proteins content, the fat content, and mineral content in the human body can be evaluated with the correlation among them. Therefore, by measuring body fat with the moisture content in the human body, all the four constituents in the human body that is, proteins, fat, minerals and moisture can be evaluated.

On the other hand, the conventional methods of measuring the human body constituents may be classified as 8-terminal, 4-terminal, and 2-terminal measurement types.

In 8-terminal measurement method, body fat can be measured with 8 terminals, which include a current supply terminal and a voltage detection terminal at each of feet and hands. The 8-terminal measurement method has an advantage that it can measure degree of inclination or deformation of the human body with different weight detection at both feet. Furthermore 8-terminal measurement method can easily evaluate the fat distribution in the human body. Nevertheless above advantages, the apparatus implemented according the 8-termial measurement method has too large size, and therefore it is a problem that the apparatus is unsuitable for a portable application.

In 4-terminal measurement method, body fat measurement can be performed by with 4 terminals which are serves as the current supply and voltage detection terminals at each of the feet and hands. The apparatus implemented according the method has complexity of the 4-terminal measurement type and is too large to be compact. Also the current supply terminal is much separated from the voltage detection terminal, there is a problem that an error due to the distance difference between the terminals may occur.

At present, to solve the above problems, 2-terminal measurement method has been studied. However, the method may not be generally used because the current supplied from the current supply terminal May 14, 2003 may disadvantageously leak to the voltage detection terminal when the current supply terminal and the voltage detection terminal are integrated in one apparatus.

On the other hand, most of the conventional body fat measuring equipments are provided with the current supply terminal and the voltage detection terminal independently. Therefore, complexites of the apparatuses are increased and their impedances between terminals are decreased, so that it is a problem that errors between the terminals may occur.

Furthermore, in the conventional body fat measuring equipment, the current supplied to inside the human body can not be maintained in a constant level and depends on variation of impedance of the human body, so that it is unsuitable for measuring body fat precisely.

Therefore, in order to solve the above problems, an object of the present invention is to provide body fat measuring equipment having a constant alternating current generating circuit which can be operated safely regardless of impedance variation of the human body.

Another object of the present invention is to provide body fat measuring equipment in which the current supply terminal is independently not required by employing a constant current circuit as a current supply source. Another object of the present invention is to provide a portable body fat measuring equipment which is small sufficient to hand-carry easily.

Another object of the present invention is to provide simply operated body fat measuring equipment which can be operated by general users without any special knowledge.

DISCLOUSRE OF INVENTION

In order to accomplish the above objects, the present invention provides a body fat measuring equipment, using a bioelectric impedance analysis, comprising: a current supply circuit; a voltage detection circuit; a conductive electrode plate contacted with a portion of the human body for measuring a impedance of the human body; a microprocessor for calculating body fat based on the measured impedance; an A/D converting circuit for converting a voltage signal detected by the voltage detection circuit into a digital signal and transmitting the digital signal to the microprocessor; data input means for inputting personal information of weight, tallness, sex and so on; and an image display device for display the measured results, wherein the current supply circuit comprises a constant current generating circuit for supplying a constant current to the human body, an alternating current generating circuit for generating a alternating current in a sinusoidal wave form, and a signal mixing circuit for mixing the generated constant current and alternating current and converting the constant current into an alternating current, thereby generating a signal having the sinusoidal wave form to measure the impedance of the human body; and wherein the voltage detection circuit comprises a voltage follower circuit.

In body fat measuring equipment according to an embodiment of the invention, the conductive electrode plate may comprise only two electrodes of which terminals are the current supply terminal for the signal mixing circuit and the terminal for the voltage detection circuit, and wherein the constant current generating circuit and the alternating current generating circuit are incorporated in the signal mixing circuit.

In body fat measuring equipment according to an embodiment of the invention, one of the electrodes may be disposed on the main body of the apparatus to be contacted with hands, and the other electrode may be connected to a cable of the apparatus to be contacted with a foot, thereby a fat distribution of whole the human body being measured with the electrodes.

In body fat measuring equipment according to an embodiment of the invention, the two electrodes may be attached to outside of a case with a hinge and a cable, thereby being contacted with both palms of the human body.

In body fat measuring equipment according to an embodiment of the invention, the two electrodes may be attached to a front of a case, thereby being contacted with both pollex of the human body. In body fat measuring equipment according to an embodiment of the invention, the signal mixing circuit may be constructed with a CMOS circuit.

In body fat measuring equipment according to an embodiment of the invention, also the conductive electrode plate comprises only two electrodes each which serve as both a current supply terminal for the signal mixing circuit in which the constant current generating circuit and the alternating current generating circuit are combined, and a terminal for the voltage detection circuit.

In body fat measuring equipment according to an embodiment of the invention, also one of the electrodes is disposed on the main body of the apparatus to be contacted with hands, and the other is connected to a cable of the apparatus to be contacted with feet, thereby a fat distribution of whole the human body can be measured with the electrodes.

In body fat measuring equipment according to an embodiment of the invention, also the two electrodes are attached to outside of a case with a hinge and a cable to be contacted with both palms of the human body. In body fat measuring equipment according to an embodiment of the invention, also the two electrodes are attached to front of a case to be contacted with both pollex of the human body.

BRIEF DESCRIPTION OF DRAWINGS

The above and other objects, advantages and features of the present invention will become apparent from the following description of preferred embodiments given in conjunction with the accompanying drawings, in which:

Fig. 1 is a circuit diagram of a body fat measuring equipment according to the present invention. Fig. 2 is a schematic perspective view of a body fat measuring equipment for a whole the human body of an embodiment according to the present invention;

Fig. 3 is views showing implementation of a body fat measuring equipment for a whole the human body of an embodiment according to the present invention in Fig. 2; Fig. 4 is a schematic perspective view of a body fat measuring equipment for upper the human body of an embodiment according to the present invention.

Fig. 5 is views showing implementation of a body fat measuring equipment for upper the human body of an embodiment according to the present invention in Fig. 4;

Fig. 6 is a schematic perspective view of a body fat measuring equipment using pollex contact as an embodiment according to the present invention.

Fig. 7 is a views showing implementation of an embodiment using pollex contact body fat measuring equipment Fig. 6 according to the present invention.

BEST MODE FOR THE PREPERRED EMBODIMENT OF THE INVENTION

Now, the preferred embodiments according to the present invention will be described in detail with reference to the appended drawings.

Fig. 1 is a circuit diagram of body fat measuring equipment according to the present invention. As shown in Fig. 1, body fat measuring equipment according to the present invention is preferably of 2-terminal measurement type. However, it is appreciated by the skilled person in the art that the present invention is able to be employed at the 4- terminal measurement type as well as the 2-terminal measurement type

The body fat measuring equipment comprises a constant current generating circuit 102, an alternate signal generating circuit 103, a signal mixing circuit 106 and voltage detection circuit 106.

The constant current generating circuit 102 employs a D.C. constant current source to measure impedance without any additional circuit for measuring the current, as described above. Also, the constant current generating circuit 102 generates a constant current Is to maintain the current supplied to the human body to be in a constant level. The constant current is about 10mA or less which is harmless to the human body. On account of the constant current source, the present invention has an advantage that over current may not be supplied to the human body, so that the area of electrode to be in contact with outside the human body can be decreased and thus the reliability of the detection can be increased.

The alternating current generating circuit 103 generates a sinusoidal wave so as to measure an internal resistance of the human body with the current passing through the skin of the human body. The alternating current generating circuit 103 can be implemented with a general sinusoidal wave generating circuit.

A signal mixing circuit 101 can be implemented with a amplify circuit in which output resistance is low and is preferably constructed with a CMOS circuit. As shown in Fig. 1, the signal mixing circuit 101 applies the current to the human body through a terminal A 104 without any current leakage towards the alternating voltage source. The signal mixing circuit 101 performs a function of preventing current from leakage as well as a function of converting the D.C. constant current into an alternating current. That is, the signal mixing circuit 101 maintains an alternating wave form in a constant level by mixing the constant current Is supplied from the constant current generating circuit 102 and the alternating wave form voltage output from the alternate signal generating circuit 103. It is preferable that a human body contact ground electrode 104, 105 constitute a measurement terminal having only tow electrodes each which serve as both the current supply electrode and the voltage detection electrode.

In the embodiment according to the present invention in which the signal mixing circuit 101, the constant current generating circuit 102 and the alternate signal generating circuit 103 are employed in the 2-terminal measurement type. However, it will be appreciated by the skilled persons in the art that the present invention can be also constructed in the 4-terminal measurement type.

In the two body contact ground electrodes 104, 105, whole current output from the constant current source is supplied to the human body, and then voltage is measured at the location which the current is supplied to the human body. Therefore, voltage drop can not caused by errors in the measuring locations.

The voltage detection circuit 106 comprises an input buffer 106. It is preferable that the input buffer 106 may employ OP-AMPs, of which input resistance is very large so that the whole current generated at the current supply terminal in the human body contact ground terminal can be applied to the human body. As described above, both the current supply terminal and the voltage detection terminal are incorporated in the human body contact ground terminal.

It is preferable that the OP-AMP in which resistance is about 10M ohm or more and a voltage follower type is employed.

In the signal amplification circuit 107 shown in Fig. 1, the signal voltage measured in the voltage detection circuit 106 is level-shifted and amplified with a voltage amplifier for an A/D conversion.

Also, the body fat measuring equipment according to the present invention includes an A/D converter and a measuring unit 109. The measuring unit 109 includes a memory, a microprocessor, input unit, and output unit.

An analog value of the measured and amplified voltage is converted into a digital value by the A/D converter.

The microprocessor calculates a human body constitution by operating the digital value.

The memory stores fonts (words), personality and measurement history. Thus, once personality is stored in the memory, thereafter the measurement can be carried out without any other independent input.

The output unit is an image display for displaying the measured result. As an example, it is preferable that body fat ration, body fat quantity and fatness are visually displayed on the liquid crystal display for user.

The input unit is means for receiving personality of user using preferably the keyboard, including a button for receiving a measurement and confirmation command. A power source apparatus (not shown) is constructed to supply via wires power from an external power source or a battery which is mounted in the apparatus in case that the apparatus is portable.

Now, the operating of body fat measuring equipment according to the present invention will be described herein after.

The principle of body fat measuring equipment according to the present invention is described as follows. The input resistance (or the input impedance) of the voltage detection device is typically very high in comparison to an impedance Z of the human body. When a constant current is applied to the human body, a voltage No is measured based on the ohm's law, that is, No = Is * Z, and current Is is substantially constant. Thus the measured voltage No is represented by No = k * Z (herein, k is constant term associated with the current and is various depending on the apparatus). Thus, the impedance of the human body Z is represented by Z = No/k.

Assuming that ideally the impedance of the skin of the human body is zero, the impedance Z is represented by Z = Ri (herein Ri is a internal resistance in the human body). Thus, the internal resistance in the human body(Ri) can be obtained with the measured voltage No.

The impedance of the skin is substantially depending on the capacitance element Cs of the skin, thereby the impedance Zc which is connected to Re in parallel is represented by Zc = l/2πfC. In consideration of the impedance Zc, the capacitance element Cs should be significantly large in order to minimize the impedance Zc. For the above reasons, the width of the terminals associated with the capacitance element Cc also should be significantly large. The more the contact aria of the terminals is increased, the more error in measuring can be decreased.

If impedance of the human body is obtained as described above, then the impedance is multiplied by any constant as known conventionally, thereby the quantity of proteins and mineral being calculated based on the basic fraction of the human body composition elements. Thus body fat can be calculated by subtracting the quantity of moisture, proteins and mineral from the input weight of user.

Fig. 2 and Fig. 3 are views showing the main structure (shown in Fig. 2) and application method (shown in Fig. 3) for measuring fatness of a whole the human body in a body fat measuring equipment of the 2 terminal measurement type according to an embodiment of the present invention. The body fat measuring equipment 21 comprises a electrode 21 for being contacted with hands of the human body, a electrode 22 for being contacted with feet, a data input unit 24 to input personality weight, tall, sex and so on, a cable 26 for connecting electrode 22 for being contacted with feet and the main structure, and an image display device 26 for showing the measured results.

In method for operating body fat measuring equipment 21, weight, tallness and sex and so on are input with the data input unit 24. Then electrode 22 disposed on one side of the apparatus 21 is contacted with one of user's hands. Then the electrode 23 disposed on the other side of the apparatus 21 is connected with one of user's feet via the cable 23 which can be extended by pulling from the apparatus 21 in order to measure the impedance of the human body. The measured result is displayed visually on the image display device 26. In that case, either of hands and either of feet are available to measure the impedance. Therefore it is also noted that the fat distribution in the human body is unbalance.

Fig. 4 and Fig. 5 are views showing the main structure (shown in Fig. 4) and application method (shown in Fig. 5) for measuring fatness of a whole the human body in a body fat measuring equipment of the 2-terminal measurement type according to an embodiment of the present invention. Fig. 4 is showing the 2 type of configuration according to the operating method of the present invention.

The body fat measuring equipment 41 comprises a electrode 42 for being contacted with left hand of the human body, a electrode 43 for being contacted with right hand of the human body, a data input unit 44 to input personality weight, tall, sex and so on, an image display device 45 for showing visually the measured results, and a cable 46 for connecting electrodes 42, 43 and the main structure.

In body fat measuring equipment 41, it is characterized that the area of the electrodes to be contacted with palm of the human body is large while body fat measuring equipment 41 is compact, thereby the error in measuring being decreased

Fig. 6 and Fig. 7 are views showing the main structure (shown in Fig. 6) and application method (shown in Fig. 7) for measuring fatness of a whole the human body in a body fat measuring equipment of the 2-terminal measurement type according to an embodiment of the present invention.

The body fat measuring equipment 61 comprises a electrode 62 for being contacted with pollex of left hand, a electrode 63 for being contacted with pollex of right hand, a data input unit 64 to input personality weight, tall, sex and so on, and an image display device 65 for showing visually the measured results.

In body fat measuring equipment 61, it is characterized that the electrodes disposed at both side of the apparatus can be contacted with both pollex of hands to facilitate the apparatus operation while body fat measuring equipment 61 can be miniaturized.

INDUSTRIAL APPLICABILITY

Having described above, it is understood by those skilled in the art that the foregoing detailed description is a specific embodiment of the disclosed apparatus and that various changes ad modifications may be made in the invention without departing from the spirit and scope thereof. Therefore the scope of the invention is defined by appended claims rather than by the description preceding them, and all changes that fall within meets and bounds of the claims, or equivalence of such meets and bounds are therefore intended to embrace by the claims. As described above, the present invention makes it possible to provide body fat measuring equipment having the circuit for generating safely an alternate constant current regardless of the impedance variation.

Also, the present invention makes it possible to provide body fat measuring equipment in which the current supply terminal is not required independently with the constant current circuit as a current supply source. Also, the present invention makes it possible to provide a portable body fat measuring equipment which is small sufficient to hand-carry easily, when body fat measuring equipment is applied to the 2-terminal measurement type.

Also, the present invention makes it possible to provide a simply operated body fat measuring equipment which can be operated by general user without any special knowledge.

Claims

CLAIMSWhat is claimed is

1. A body fat measuring equipment, using a bioelectric impedance analysis, comprising: a current supply circuit; a voltage detection circuit; a conductive electrode plate contacted with a portion of the human body for measuring an impedance of the human body; a microprocessor for calculating body fat based on the measured impedance; an A/D converting circuit for converting a voltage signal detected by the voltage detection circuit into a digital signal and transmitting the digital signal to the microprocessor; data input means for inputting personal information of weight, tallness, sex and so on; and an image display device for display the measured results, wherein the current supply circuit comprises a constant current generating circuit for supplying a constant current to the human body, an alternating current generating circuit for generating an alternating current in a sinusoidal wave form, and a signal mixing circuit for mixing the generated constant current and alternating current and converting the constant current into an alternating current, thereby generating a signal having the sinusoidal wave form to measure the impedance of the human body; and wherein the voltage detection circuit comprises a voltage follower circuit.

2. A body fat measuring equipment according to claim 1, wherein the conductive electrode plate comprises only two electrodes of which terminals are the current supply terminal for the signal mixing circuit and the terminal for the voltage detection circuit, and wherein the constant current generating circuit and the alternating current generating circuit are incorporated in the signal mixing circuit.

3. A body fat measuring equipment according to claim 2, wherein one of the electrodes is disposed on the main body of the apparatus to be contacted with hands, and the other is connected to a cable of the apparatus to be contacted with a foot, thereby a fat distribution of whole the human body being measured with the electrodes.

4. A body fat measuring equipment according to claim 2, wherein the two electrodes are attached to outside of a case with a hinge and a cable, thereby being contacted with both palms of the human body.

5. A body fat measuring equipment according to claim 2, wherein the two electrodes are attached to a front of a case, thereby being contacted with both pollex of the human body.

6. A body fat measuring equipment according to clam 1, wherein the signal mixing circuit is constructed with a CMOS circuit.