KR100542795B1 - Portable Communication Terminal Having Body Fat Measurement - Google Patents

Abstract

The present invention is a portable communication terminal having a body fat measurement function for measuring the body fat amount more accurately by correcting the measurement error of the human resistance caused by the reduction of the ground area of the measurement terminal according to the miniaturization of the device by the DC resistance measurement value of the human body It is about.

According to the present invention, a body fat measuring device is incorporated into a portable communication terminal so that many people who are interested in a diet can easily measure body fat without any spatial, temporal, and cost constraints whenever necessary, and also reduce the size of the measuring device according to the miniaturization of the device. By correcting the measurement error caused by the reduction in the contact area of the body through the DC resistance measuring means has an effect that can accurately measure the amount of fat.

Body fat, obesity, bioelectrical impedance analysis, portable communication terminal

Description

Portable Communication Terminal Having Body Fat Measurement             

1 is a front view and a side view showing a portable communication terminal having a conventional body fat measurement device.

Figure 2 is a block diagram of a portable communication terminal having a body fat measurement function as an embodiment of the present invention.

3 is a block diagram of a component for performing body fat measurement in accordance with the present invention.

4 is a detailed view of a DC resistance measuring circuit of the circuit of FIG.

Figure 5 is an equivalent circuit diagram of a schematic human body applied to the present invention.

6 is a graph showing an AC impedance value and a DC resistance value measured according to an embodiment of the present invention.

7 is a conceptual diagram of an analog switch according to the present invention.

8 is an embodiment of a portable communication terminal having a body fat measurement function according to the present invention.

The present invention relates to a portable communication terminal having a body fat measurement function, and more particularly, by correcting a measurement error for a human body resistance caused by a reduction in the ground area of a measurement terminal according to the miniaturization of a device by measuring a DC resistance measurement value of a human body. The present invention relates to a portable communication terminal having a body fat measurement function for accurately measuring the amount of body fat in the human body.

Medically, obesity is not just about the weight and the weight of the body, but rather the amount of fat in the body is judged according to the high and low. As a method for measuring the state of obesity, various methods such as standard weight method, body mass index method, aquatic body density method, skin wrinkle thickness measurement method are disclosed, but the most reliable method is bioelectric impedance analysis method at present.

Bioelectrical impedance analysis, commonly referred to as BIA, was reported by Hoffer in 1969 to report that body water content is inversely related to the body's electrical resistance, and its reliability has been steadily studied since the 1980s by many doctors, nutritionists, and gymnasts. The accuracy is now recognized.

The main components of the body can be divided into four components: water, protein, body fat, and minerals. Protein and body moisture are the main components that form muscles, and they have a proportional relationship with each other. It is water and the remaining 27% is known to be protein. Minerals are also known to form bones and their weight is closely related to muscle mass. Therefore, the current flows through the water and not through the fat, so the body is measured by measuring the impedance, and the protein, body fat, and inorganic mass, which are the remaining components of the human body, are obtained by the correlation between the components of the human body. The amount of body fat can be determined by measuring the amount of water.

As a technique for measuring body moisture by the BIA method, conventionally, a body fat analyzer which measures a impedance by applying a weak alternating current by contacting an electrode to an external part of the body and measuring a resistance value accordingly is provided. At this time, the electrode is divided into 8-terminal method, 4-terminal method, 2 terminal method.

The eight-terminal method measures body fat with eight electrodes using current supply terminals and two voltage measurement terminals on each hand and foot, and measures body tilt at the same time by dividing the weight on both sides of the foot. There is an advantage. However, the eight-terminal measurement method using eight terminals is easy to check the distribution of body fat, but the size of the equipment is difficult to apply portable.

The four-terminal method consists of a single electrode consisting of a current supply terminal and a voltage measurement terminal, each of which attaches a total of four terminals to the hands and feet of the human body. Since the terminal and the measurement terminal are separated, there is a problem that an error due to the spacing between terminals always occurs.

Although the two-terminal method can be miniaturized by integrating the current supply stage and the voltage measurement stage, it is recognized as a desirable method for the development of a portable body fat measurement system.However, the leakage error of the current measurement voltage and the contact terminal Problems such as errors due to area reduction remain technical challenges.

1 is a portable communication terminal having a conventional body fat measuring device, which is a portable communication terminal having a body fat measuring device according to the actual measurement value as the contact area of the contact terminal 11 in contact with the human body decreases due to the miniaturization of the device. There is a big error, and there are many difficulties in practical use.

The reason for this measurement error is generally the impedance value needed to measure body fat in the human body, which is the internal impedance of the human body ignoring skin components.If the area of the contact terminal decreases due to the miniaturization of the device, the skin of the human body Since the closing area is smaller, the capacitance of the skin component is smaller, so that the value of the skin impedance is relatively increased, which greatly affects the measurement of the internal impedance value of the human body.

That is, when the area of the contact terminal 11 grounded on a part of the human body becomes narrow in order to supply a current to the human body and measure the voltage value accordingly, a sensitive response according to the skin impedance rather than the impedance of the human body in the measurement value This will cause a large error in the impedance value required for measuring the amount of fat in the body.

Therefore, the measurement of the impedance value through the use of the contact terminal 11 having a narrow ground area of the human body and the calculation of the body fat amount without correction include the impedance value of the skin component, not the pure internal impedance value. The problem of calculating arises.

In addition, the portable communication terminal having a conventional body fat analyzer has a problem that requires a new mold or a process according to the configuration change of the existing terminal by adopting a structure to newly configure the contact terminal 11 to the outside.

The present invention has been made to solve the above problems, it is possible to carry through the miniaturization of the equipment and to combine the body fat measurement device with a portable communication terminal carried by most of the modern people easily space, time, cost constraints if necessary It is an object of the present invention to provide a portable communication terminal having a body fat measurement function that can be performed without the body fat measurement.

In addition, another object of the present invention is to provide a portable communication terminal having a body fat measurement function that can measure a more accurate body fat amount through a correction means for correcting the error caused by the reduction of the contact area of the reduced measuring stage according to the miniaturization will be.

In addition, another object of the present invention is to provide a portable communication terminal having a body fat measurement function having a stable constant current source and a constant voltage source so that the power applied to the human body during the measurement is irrelevant to the human body's impedance change and harmless to the human body.

In addition, another object of the present invention is to avoid the production of a new mold by using a protruding terminal of the existing keypad without a structural change in the manufacturing process of the existing portable communication terminal, and to avoid the production of new molds and manufacturing process using the existing production facilities In this regard, there is an effect of providing a portable communication terminal having a body fat measurement function without difficulty of new equipment.

In order to achieve the above object, the present invention provides a mode selection module for selecting a communication mode and a body fat measurement mode; A conductive human ground terminal for electrical contact with the human body; A body resistance measuring unit for measuring a body resistance value; An A / D conversion circuit for converting the signal output from the human body resistance measuring unit into a digital signal; A microprocessor configured to perform a calculation required to calculate body fat mass using the converted digital signal; And a screen display unit for displaying the body fat measurement information.

The human body resistance measuring unit includes an AC impedance measuring circuit and a DC resistance measuring circuit, and an analog switch for selectively operating the AC impedance measuring circuit and the DC resistance measuring circuit under the control of the microprocessor,

The microprocessor provides a portable communication terminal having a body fat measurement function, comprising correction means for correcting an impedance value measured through the AC impedance measuring circuit with a resistance value measured through the DC resistance measuring circuit. Characterized in that.

The human body resistance measuring unit is a power supply circuit for applying power to the AC impedance measuring circuit,

And a constant current generating circuit for generating a constant current, an alternating current generating circuit for generating an AC signal of a sine wave, and a signal mixing circuit for mixing the constant current and the AC signal of the sine wave.

The human body resistance measuring unit may include a constant voltage source as a power supply circuit for applying power to the DC resistance measuring circuit.

The conductive human earth terminal is characterized by consisting of two contact electrodes by a two-point measurement method, characterized in that attached to the input of the portable communication terminal, the analog switch is characterized in that the MOS switch.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

Figure 2 is a block diagram of the configuration of a portable communication terminal having a body fat measurement function as an embodiment of the present invention.

The block diagram has a configuration of a conventional portable communication terminal and further includes a human body resistance measuring unit 29. The transmitter 22, the handset 23, and the wireless transmitter / receiver 24 have a conventional communication function. The display unit 26, the input unit 27, the memory 25 and the microprocessor 21 has a conventional communication function and at the same time is configured to perform the body fat measurement function according to the present invention, The human body resistance measuring unit 29 is a component for measuring a resistance value inside the human body required for measuring body fat. Incidentally, the A / D conversion unit 30 for converting the analog signal output from the human body resistance measuring unit 29 to a digital signal is configured, and the mode for switching to the corresponding mode between the communication function and the body fat measurement function, and setting key The selection module 28 is configured.

In the microprocessor 21 performing the communication function, the microprocessor 21 controls operation modules such as the input unit 27, the handset 22, the handset 23, and the wireless transmitter / receiver 24, and performs the body fat measurement. And to perform arithmetic processing to calculate body composition values with the measured and digitized measured values. In addition, the screen display unit 26, the memory 25 and the mode selection module 28 control the body fat measurement function at the same time as performing the communication function.

The memory 25 stores data and personal information on a communication function and a measurement history of the body resistance measuring unit 29. Therefore, by storing the data processed by the existing communication device such as phone number and schedule data, as well as by storing the personal information, the body fat is measured using the initial data stored by the user without any additional data input thereafter. Measurement becomes possible.

The screen display section 26 is configured to display a display on the communication function and a display on the body fat measurement information. In one embodiment, it is preferable to configure a liquid crystal display that allows the user to check with the naked eye.

The input unit 27 is preferably configured as a keypad and used for input of numbers and data on a telephone function and at the same time for input of personal information and the like on a body fat measurement function. It is configured to include a function for entering a command for such. In addition, in accordance with a feature of the present invention is configured to be installed on a part of the keypad is a human earth terminal connected from the body resistance measuring unit 29. The human earth terminal will be described later in detail.

The power supply (not shown) is configured to receive power from a battery mounted therein.

3 is a block diagram of a component for performing body fat measurement in accordance with the present invention.

In performing the body fat measurement function according to the present invention, the human body resistance measuring unit 29, the human body grounding terminal 36, the A / D conversion unit 30, the microprocessor 21, and the memory 25 is configured. In particular, the human body resistance measuring unit 29 includes a constant current generating circuit 31, an AC signal generating circuit 32, a signal mixing circuit 33, an analog switch 37, an AC impedance measuring circuit 34 and a DC resistance measuring circuit ( 35).

The constant current generating circuit 31, which is a constant current source, is configured to supply a current necessary for impedance measurement without an additional circuit such as current measurement, and the constant current generating circuit 31 preferably uses a DC constant current source.

In addition, the constant current generation circuit 31 generates a constant current to maintain a constant current supplied to the human body and supplies a constant current of 10 mA or less, a level harmless to the human body to have safety. Therefore, the use of a constant current source provides a constant current without excessive human body, thereby reducing the ground area of the electrode and having the advantage of maintaining accurate reliability in the measurement of impedance.

The AC signal generating circuit 32 is composed of a general sinusoidal wave generating circuit to generate a voltage of a sinusoidal wave so that the internal resistance can be measured by passing the skin resistance of the human body.

The signal mixing circuit 33 is implemented using an amplifier circuit having a low output resistance. Preferably, the signal mixing circuit 33 converts the DC constant current into an AC signal without leakage current to an AC voltage source by using a CMOS circuit, and thus the first terminal 36a. AC current is applied to the human body through). That is, the signal mixing circuit 33 mixes the constant current supplied by the constant current generating circuit 31 and the voltage of the AC waveform output from the AC signal generating circuit 32 to maintain a constant AC waveform. Produce it and apply it to the human body.

The AC waveform constant current is composed of the human body ground terminal 36 composed of a conductor to be applied to ground to the human body, the human body ground terminal 36 according to the present invention for miniaturization is the contact electrode is integrated with the current supply terminal and the voltage measuring terminal It is preferable to consist of having only two electrodes.

In addition, the AC impedance measuring circuit 34 is composed of an input buffer, the input buffer so that the AC waveform constant current generated in the signal mixing circuit 33 is applied to the human body without leakage from the human ground terminal 36. It consists of OP-AMP with large input resistance. The OP-AMP is preferably 10M ohm or more and it is preferable to use a voltage follower circuit in the circuit configuration.

Therefore, the human ground terminal 36 composed of the two electrodes is applied to the human body all the current coming from the constant current and the voltage is measured immediately at the position where the current is supplied, thereby not causing a voltage drop problem due to a position error during the measurement. It does not work.

The DC resistance measuring circuit 35 is configured to measure the resistance value of the human body in order to correct an error caused by the reduction of the contact surface of the human earth ground terminal 36, and uses a constant voltage source separate from the AC waveform constant current.

The analog switch 37 is configured to form a connection circuit that obtains each measurement value through the selective connection of the human earth terminal 36 to the AC impedance measurement circuit 34 and the DC resistance measurement circuit 35. The analog switch 37 is operated under the control of the microprocessor 21 to turn on / off the circuit of the human body resistance measuring unit 29 with the power supply unit, and the human body ground terminal 36 and the AC impedance measuring circuit ( 34) or to make a selective connection of the DC resistance measurement circuit (35).

The A / D conversion circuit 30 level shifts and amplifies a signal measured by the AC impedance measuring circuit 34 and the DC resistance measuring circuit 35 to facilitate A / D conversion using a voltage amplifier. Afterwards, the A / D converter converts an analog signal to digital to calculate and process the applied voltage value in the microprocessor 21.

The measured and converted digital signal is computed in the microprocessor 21 and stored in the memory 25.

4 is a configuration diagram of a DC resistance measurement circuit.

The DC resistance measuring circuit 35 is composed of an inverting amplifier circuit using an OP-AMP.

Referring to FIG. 4, the DC resistance measuring circuit 35 including the amplifier 43 includes a constant voltage source 41 to which a fixed voltage is supplied from a voltage source of which the cathode is grounded, and is in series with the constant voltage source 41. The fixed resistor 42 Ri is connected to the first terminal 36a and the second terminal 36b, and a part of the human body is grounded to form the human body resistance 44 Rf.

The DC resistance measuring circuit 35 uses a fixed voltage to calculate the supply voltage value according to the ancillary voltage measuring unit without using the fixed value of the constant voltage source 41 for calculation. Will yield

The calculation formula of the body resistance 44 Rf value is as follows.

The Vi and the fixed resistor 42 Ri of the constant voltage source 41 are fixed values, and the output voltage 45 V0 is measured through the DC resistance measuring circuit 35 and the A / D change circuit 30. The calculated value. The microprocessor 21 calculates the human body resistance 44 Rf by substituting the fixed value and the calculated value into the above equation. At this time, the body resistance 44 Rf value is a DC resistance value and is not an overall impedance value required for body fat measurement.

5 is a schematic equivalent circuit diagram of the human body.

Referring to FIG. 5, the body resistance 44 Rf is a skin impedance R skin component (hereinafter referred to as Rs) 51 and a C skin component (hereinafter referred to as Cs) 53 and an internal resistance R body (hereinafter referred to as Rb). 52, the AC impedance measuring circuit 34 passes the AC waveform constant current through the Cs component 53 of the skin impedance components to measure the internal resistance Rb 52, and the DC resistance measuring circuit. In the reference numeral 35, the constant voltage source 41 is used to measure Rs 51 and internal resistance Rb 52 of the skin impedance components.

In this case, in the actual measurement to which the human earth terminal 36 is small or when the skin is dry, the Rs component 51 of the skin impedance affects the calculation of the overall body fat measurement value. Among the skin impedance components measured in the circuit 35, the value of Rs (51) is negligible at the level of several hundred K ohms or the internal resistance Rb (52) is hundreds of ohms. ) Rf value is the skin impedance component Rs (51) value of both terminals.

Therefore, the human body resistance measuring unit 29 configured in the portable communication terminal according to the present invention is configured by a small human body ground terminal, the error generated sensitively according to the state of the human body ground terminal 36 is calculated by the DC resistance measuring circuit. The above error can be corrected by reflecting the skin impedance Rs 51 value.

FIG. 6 is a graph showing an AC impedance measurement value and a DC resistance measurement value according to a contact state between the human earth terminal 36 and the skin.

The graph by measuring the DC resistance and AC impedance several times with various contact states such as attaching the human earth terminal 36 to the human body wide, attaching small, sweating, dry, lightly touching or pressing with force. You get In this case, when the measured values are arranged from the low value to the high value on the x-axis according to the DC resistance and the AC impedance value, the deviation of the DC resistance and AC impedance values is shown as shown in the graph.

The DC resistance and AC impedance for the same person should be measured the same, but the DC resistance and AC impedance may vary depending on the contact surface of the human body. In particular, the DC resistance shows a greater deviation than the AC impedance. have.
Therefore, the following equation is used to get constant measured value by eliminating the variable factor according to the contact state. That is, the graph of FIG. 6 shows that the DC resistance value and the AC impedance value have a linear proportionality. Therefore, the variable factors for the contact state can be eliminated as follows.

Linear equation based on AC impedance measurement graph

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y ₁ = a ₁ × x ₁ + b ₁ ①

Linear equation based on DC resistance measurement graph

y ₂ = a ₂ × x ₂ + b ₂ ②
Where y ₁ and y ₂ are the measured AC impedance and the DC resistance, respectively, and x ₁ , x ₂ is a variable representing a contact state, a ₁ and a ₂ are slopes of each straight line, and b ₁ and b ₂ are intercepts of straight lines.
Summarizing the above ① and ② expressions with respect to x ₁ and x ₂ , respectively,
x ₁ = (y ₁ -b ₁ ) / a ₁ ③
x ₂ = (y ₂ -b ₂ ) / a ₂ ④
Since the contact state for the DC resistance value and the AC impedance value is the same, let x ₁ = x ₂ and find the relation of y ₁ and y ₂ .
y ₁ = a ₁ / a ₂ × y ₂ + b ₁ -a ₁ / a ₂ × b ₂ ,
b ₁ -a ₁ / a ₂ × b ₂ = y ₁ -a ₁ / a ₂ × y ₂
That is, y = y ₁ -k × y ₂ ⑤
It can be standardized by the impedance correction formula required to measure body fat.
Where k (= a ₁ / a ₂ ) is the value measured by the experiment, not the value that depends on the measurement object, but the value that depends on the contact state, and y (= b ₁ -a ₁ / a ₂ × b ₂ ) Is the impedance value to be measured.

As can be seen in the graph of FIG. 6, the measured value has a proportional relationship, and by correcting the DC resistance value at the AC impedance value through the above equation, the contact state of the human body contacting part of the human earth terminal 36 is reached. A stable body fat measurement is calculated regardless of the change. In the above correction formula, the k value is preferably calculated by applying a test value according to various parameters of the grounding terminal 36 such as the size and the material of the ground plane, and the grounding terminal having the same size and material. For (36), an operation is performed by substituting the same k value previously calculated into the above equation. If the ground plane is large according to the contact state, the k value is small because the skin resistance is less affected. If the ground plane is small, the k value is increased. Therefore, in general, the meaning may be small in the current large-capacity equipment of which the ground plane is largely configured, but in the configuration of the miniaturization according to the present invention, the correction by the k-value has a very large meaning.

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7 is a conceptual diagram of an analog switch according to the present invention.

The analog switch 37 is a switch operated under the control of the switch control stage 72 included in the microprocessor 21. When the body fat measurement mode is selected, power is supplied and the human body ground terminal 36 The analog value is transmitted from the input terminal 71 to the output terminal 73 as it is, and at this time, the human body ground terminal 36 is selectively connected to the AC impedance measuring circuit 34 and the DC resistance measuring circuit 35. It is preferable to apply a MOS switch, which is preferably composed of MOS, to the analog switch 37, but it is natural that the analog switch 37 can be configured with other switches.

8 is a configuration diagram of a contact terminal of a portable communication terminal having a body fat measurement function as an embodiment of the present invention.

The human body ground terminal 36 is formed by using some keys of the keypad of the input unit 27 as conductive buttons. That is, two buttons of the keypad are made of a metal material that can be electrically connected to the signal mixing circuit 33, the AC impedance measuring circuit 34, and the DC resistance measuring circuit 35. In order to implement the two-point measuring method according to the present invention, it is preferable that the two buttons 81 are separated from each other.

Therefore, the user can easily measure body fat by touching both thumbs on the conductive button 81. An example of a device that can be used as a portable communication terminal for combining body fat measurement by configuring the conductive button is an example of a mobile phone, a PDA, an electronic notebook, and the like.

Hereinafter, the operation of a portable communication terminal having a body fat measurement function according to the present invention will be described with reference to FIGS. 2 and 3.

The present invention is characterized by configuring the human body resistance measuring unit 29 in a portable communication terminal performing a communication function anytime, anywhere easy to measure the body composition.

When the body fat measurement mode is selected through the mode selection module 28 configured in the portable communication terminal, and the two parts of the human body are contacted on the conductive button 81 which is the human earth terminal 36, the microprocessor 21 is The analog switch 37 is turned on to selectively connect the AC impedance measuring circuit 34 and the DC resistance measuring circuit 35 to the human earth terminal 36 to form a closed circuit.
When the AC impedance measuring circuit 34 is connected to the human body ground terminal 36 by the analog switch 37, the signal mixing circuit 33 is connected through the conductive button 81 which is the human body ground terminal 36. In addition to supplying the AC waveform constant current generated by the AC impedance measurement circuit 34 to measure the voltage.
On the other hand, when the DC resistance measurement circuit 35 is connected to the human body ground terminal 36 by the analog switch 37, the output voltage 45 is measured by applying the constant voltage source 41 as described above.

The voltage measured by the AC impedance measuring circuit 34 and the DC resistance measuring circuit 35 is amplified and transferred to the microprocessor 21 through the A / D conversion circuit 30.
The microprocessor 21 has an alternating current impedance based on a voltage ratio measured by the alternating current impedance measuring circuit 34 and a current ratio (Z = V / I) applied through the conductive button 81 which is the human earth terminal 36. The value Z = V / I (corresponding to y ₁ in the above correction formula) is calculated, and the output voltage V _o 45 measured by the DC resistance measurement circuit 35 and the applied constant voltage V _i ( 41) and a DC resistance value (R _f = V _o / V _i × R _i ) (corresponding to y ₂ in the above correction equation) using the fixed resistance (R _i ) 42, and then k and the set k The calculation is performed using the value (determined through the experiment according to the contact state of the conductive button) to calculate an accurate impedance value for the measurement of body fat in which the error caused by the narrow human earth terminal 36 is corrected.

The corrected impedance value is again calculated by the microprocessor 21 to calculate a corresponding body fat amount, and is displayed on the screen display unit 26. Body specific emission calculation method using the impedance is a known technique, the description thereof will be omitted.

When the user completes the measurement, the mode is set again to perform a communication function through the mode selection module 28, and the switch control stage 72 configured in the microprocessor 21 according to the mode setting is connected to the analog switch 37. ) To turn off the circuit of the human body resistance measuring unit 29.

Although the structure of the human body resistance measuring unit which can be said to be a characteristic element of the present invention is described as a portable communication terminal structure having a two-terminal body fat measurement function in the present specification, it will be understood by those skilled in the art that such a configuration can be applied to four-terminal measurement. Could be.

In the detailed description according to the present invention has been described with respect to specific embodiments will be understood by those skilled in the art. Of course, various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the above-described embodiments, but should be defined not only by the claims below, but also by those equivalent to the claims.

As described above, the present invention makes it possible to carry the device through miniaturization of equipment, and to connect the measuring device to a portable communication terminal carried by most of the modern people, so that many people who are interested in diet can easily use space, time and cost constraints whenever necessary. There is an effect of providing a portable communication terminal having a body fat measurement function to perform a body fat measurement without.

In addition, the present invention has the effect of providing a portable communication terminal having a body fat measurement function capable of measuring a more accurate body fat amount by correcting the error caused by a reduction in the contact area of the reduced measurement stage according to the miniaturization.

In addition, the present invention has the effect of providing a portable communication terminal having a body fat measurement function having a stable constant current source and a constant voltage source so that power applied to the human body during the measurement is irrelevant to the human body's impedance change and harmless to the human body.

In addition, the present invention avoids the manufacture of new molds by using the protruding terminals of the existing keypad without changing the structure in the existing manufacturing process of the portable communication terminal, and avoids the manufacture of new molds and uses the existing production facilities in the new manufacturing process. It is effective to provide a portable communication terminal having a body fat measurement function without difficulty of installation.

Claims (6)

A mode selection module for selecting a communication mode and a body fat measurement mode; A conductive human ground terminal for electrical contact with the human body; A body resistance measuring unit for measuring a body resistance value; An A / D conversion circuit for converting the signal output from the human body resistance measuring unit into a digital signal; A microprocessor configured to perform a calculation required to calculate body fat mass using the converted digital signal; And a screen display unit for displaying the body fat measurement information. The human body resistance measuring unit, A power supply circuit for applying current to the human body through the human earth ground terminal; An AC impedance measuring circuit for measuring AC impedance by the voltage measured through the human earth terminal; DC resistance measuring circuit for measuring the DC resistance using a constant voltage source; And An analog switch for selectively operating the AC impedance measuring circuit and the DC resistance measuring circuit under the control of the microprocessor, The microprocessor is a portable communication terminal having a body fat measurement function, characterized in that for correcting the impedance value measured by the AC impedance measuring circuit with the resistance value measured by the DC resistance measuring circuit. The method of claim 1, wherein the power supply circuit, A constant current generating circuit for generating a constant current; An AC generating circuit for generating an AC signal of a sine wave; And And a signal mixing circuit for generating an AC waveform constant current by mixing the constant current and the AC signal of the sinusoidal wave. delete The body fat measurement function of claim 1, wherein the conductive human earth terminal is two contact electrodes using a two-point measurement method, and the two body keys separated from each other at an input of a portable communication terminal are used as conductive buttons. Portable communication terminal. delete The portable communication terminal of claim 1, wherein the analog switch is a MOS switch.

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