KR20070044825A - 2-point body fat analysing method not using steady-alternate current source - Google Patents

Abstract

In the present invention, in the measurement of body fat through a bioelectrical impedance analysis (BIA) method, which is widely used in a body fat analyzer, the most common four-point and two-point methods in a portable body fat analyzer can be implemented more simply and at a lower cost. It is about how it can be.

The two-point measuring method using the AC constant current source can be relatively simpler and more compact than the four-point measuring method. However, while the conventional method has to produce a constant current source, in the present invention, the source signal does not necessarily need to be a constant current source, and generates a signal having a suitable size within a signal range that does not harm the human body, thereby causing an impedance and This method calculates the impedance of the human body by the difference in voltage according to the proportion of the human body's impedance. Such an invention can reduce the cost and size of the body fat analyzer, making the product cheaper and more convenient for the user to carry.

Body Fat, Impedance, BIA, 2 Point

Description

2-point Body Fat Analysing Method Not Using Steady-Alternate Current Source}

1 is a block diagram of the contents of the present invention.

Figure 2 is a schematic diagram showing an example of a portable four-point measuring device for measuring body fat using a bioelectrical impedance analysis method.

3 is a schematic configuration diagram showing an example of a portable two-point measuring device for measuring body fat using a bioelectrical impedance analysis method.

4 is a block diagram of the principle of the two-point body fat measurement method using an AC constant current source.

5 is a block diagram of the principle of the two-point body fat measurement method without using the AC constant current source expressing the principle of the present invention.

Figure 6 is an example showing the configuration of a body fat analyzer that can be implemented using an example of a modular form that can be implemented by the method of the present invention.

※ Explanation of codes for main parts of drawing

1: microprocessor

2: AC signal generator

3: internal impedance

4: Terminal 1

5: Terminal 2

6: amplifier

7: level detection unit

8: analog / digital converter

The present invention relates to a two-point body fat measurement method without using an AC constant current source among methods for measuring body fat through a bioelectrical impedance analysis (BIA) method.

Commonly used obesity measurement methods include bioelectric impedance analysis, standard weight method, body mass index method, underwater body density method, skin wrinkle thickness measurement method. Among the above methods, the bioelectrical impedance analysis method was proved by Hoffer in 1969 by a body inversely related to the body's electrical resistance, and was proved by many doctors, nutritionists, and gymnasts in the 1980s. Moreover, it is widely commercialized to improve the accuracy of the body composition analysis according to the bioelectrical impedance analysis method with the development of the technology.

Obesity is a figure expressed as the ratio of body fat to body weight. Obesity is also important because it is associated with various adult diseases such as diabetes, myocardial disorders, hypertension, arteriosclerosis, fatty liver, etc., and is an important figure that can represent a person's physical health. As dietary health increased and obesity increased, health became an important concern. Obese people want to keep their bodies healthy by dieting or exercising. Previously, they did not know their physical condition well, and lacked knowledge of which exercise or which diet method to choose. Nowadays, however, they are getting professional advice from hospitals and health clubs to fit their physical needs. Therefore, the general public often wants to know about the degree of obesity of his body. However, most of the body fat analyzers on the market are expensive and bulky, which makes it difficult for the general public to purchase and has the hassle and considerable economic burden of having to go directly to a hospital or health examination room for measurement. Therefore, those who want to manage themselves continuously hope that body fat measurement equipment will be provided inexpensively enough for the general public to use. Accordingly, there is a need for a device that can easily measure body fat, and portable and four-point and two-point measuring devices are available.

The bioelectrical impedance method is based on the fact that current flows through moisture in the human body. This means that the more muscles, the higher the water content in the human body, the higher the water content, the easier the current flows to the body, while the higher the body fat content, the greater the resistance is applied to the current flow. Since the water content in the body maintains a certain ratio with the amount of lean body mass, the impedance of the body can be obtained by measuring the current flowing along the body moisture and measuring the voltage, and the lean body mass amount can be obtained from this. Since fat contains little water, it is not a component that can be directly measured by the bioelectrical impedance method unlike fat removal. However, since the sum of body fat mass and lean body mass corresponds to body weight, it is possible to calculate the amount of body fat from the difference between the two values by measuring the weight and calculating the lean body mass by the impedance measurement of the body.

The configuration diagram of a portable body fat analyzer using a conventional impedance is shown in Figs. These methods are all divided into four-point or two-point measurement methods using an AC constant current source. Figure 2 is a four-point measuring method, there are four body contact terminals, and two terminals emit an AC constant current signal, and accordingly, a method for obtaining the body's impedance by measuring the voltage generated in the body at another two terminals. The configuration diagram. 3 is a configuration diagram of a method for obtaining an impedance of a body by measuring an voltage generated at the same terminal by sending an AC constant current signal to two terminals having two body contact terminals in a two-point measuring method.

However, the measurement method using the AC constant current source as described above requires a feedback circuit that allows a constant current to flow according to different impedances because the body impedance is different for each measurer. The existence of such a circuit is a cost increase factor of the product, which is a constraint to realize popularization and low price as a portable product.

The present invention implements the bioelectrical impedance method as a two-point measurement method using no AC constant current source. It is a key part of the present invention to obtain the impedance of a measurer even though the current flowing through the body varies depending on the impedance of each measurer by flowing a minute alternating current signal having an arbitrary voltage that is not harmful to the human body. At this time, the AC signal flowing to the body need not be a constant current source.

The measurement method allows any alternating current signal source to be supplied to the body through the resistance of a suitable internal value. 5 is a schematic diagram of this electrical analysis. The arbitrary AC signal voltage V1 determines the total impedance of the internal resistance Z1 and the body impedance Z2, that is, the current I flowing through the impedance Zt, which is the current flowing through the internal resistance Z1 and the current flowing through the body impedance Z2. Therefore, the voltage of V2 is generated according to the current I flowing through the impedance Z2 of the body. By measuring this voltage, you can find your body's impedance.

Impedance can be calculated by the formula of ohms.

V = IZ (V = voltage, I = current, Z = impedance)

Accordingly

V1 = ZtI = (Z1 + Z2) I = Z1I + Z2I = Vs + V2

Here, if the AC signal voltage V1 and the voltage V2 generated by the body impedance Z2 are read by AD conversion, the voltage Vs across the internal resistance Z1 can be known, and since Z1 is a known value, I can be obtained.

Vs = V1-V2 = Z1I

ego,

I = Vs / Z1

Thus the body's impedance

Z2 = V2 / I

Can be obtained by

After the impedance of the human body is obtained, it is calculated by multiplying a random constant as known in the art, and accordingly, the remaining proteins and minerals are calculated according to the basic composition ratio of the human body. The body fat is calculated by subtracting water, protein, and minerals from the input weight. The configuration in which these processes are performed is shown in FIG. Two parts of the body come into contact with the terminals 4 and 5 of FIG. 1, and an arbitrary signal is generated from the 2 AC signal generators of FIG. 1 under the control of the microprocessor of FIG. It is supplied to the body through 1, 4 and 5 terminals. Here, the body impedance applied to the 4 and 5 terminals of FIG. 1 is proportional to the internal impedance of the 3 internal impedance of FIG. 1 and the 4 and 5 terminals of FIG. 1 based on the signal level generated by the AC signal generator of FIG. 1. The level value is determined. The configuration thereof is shown in FIG. Thus, the level of the two AC signal generators of FIG. 1 and the level of the body measured at the four terminals of FIG. 1 are amplified while passing through the six amplifiers of FIG. 1, and the one microprocessor of FIG. Digitize for read Using this value, the microprocessor of Figure 1 calculates the impedance value and calculates the amount of other body components by the equations shown above.

Such a circuit configuration can realize a very small body fat measurement function, which can be modularized so that it can be added as an additional function to various devices including portable devices such as MP3, DMB, PMP, mobile phones, radios and digital cameras.

Conventional two-point measuring method has been relatively small compared to the method having a four-point or more measuring terminal and can realize a low cost of the product.

The present invention is implemented to measure the impedance of the body even if composed of any AC signal without the need for the AC constant current source circuit portion in the two-point measurement method. Therefore, the circuit configuration cost can be reduced and further miniaturized by the reduction of the number of parts, which makes it easier to add as an additional function to portable equipment as well as general body fat measurement equipment.

Claims (4)

A measurement method for calculating body fat without using an AC constant current source in a two-point measurement method; How to measure body fat according to internal resistance and impedance ratio of body using arbitrary AC signal without using AC constant current source as signal source to be used for measurement The method of claim 1 An A / D conversion circuit for delivering an arbitrary alternating signal and a voltage signal measured at the body impedance to a microprocessor; A microprocessor for calculating body fat based on the measured value; A serial interface or bus interface for inputting the individual's weight, height, gender, age, and outputting a calculated result; The method of claim 1 A module which can be used universally for body fat measurement by arranging necessary component elements on a printed board; Using paragraph 3 Body fat analyzer using a body fat measurement module in addition to products such as MP3, DMB, DAB, PMP, mobile phones, telephones, digital cameras, radios, desktop computers, laptops, PDAs, mice, etc .;

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