Skin condition estimating apparatus

• US 20050203435A1
• Filed: 03/07/2005
• Published: 09/15/2005
• Est. Priority Date: 03/15/2004
• Status: Abandoned Application

• Current Assignee: Tanita Corporation (Tanita)
• Original Assignee: Tanita Corporation (Tanita)
• Inventors: Nakada, Masato
• Application Number:
  US11/072,300
• Publication Number:
  US 20050203435A1
• Time in Patent Office: Days
• US Class Current: 600/547
• CPC Class Codes: A61B 5/0531 Measuring skin impedance
• CPC Class Codes: A61B 5/0537 Measuring body composition by impedance, e.g. tissue hydration or fat content
• CPC Class Codes: A61B 5/442 Evaluating skin mechanical properties, e.g. elasticity, hardness, texture, wrinkle assessment

Abstract

There is provided a skin condition estimating apparatus which allows a user to know a skin condition by more sensory characteristics. In impedance measuring means 101, a contact impedance and an internal impedance are measured. In biological equivalent model associated parameter estimating means 102, parameters associated with an equivalent model constituting a living tissue are estimated based on the measured internal impedance. In skin condition estimating means 103, a skin condition is estimated based on at least one of the measured contact impedance, the measured internal impedance, and the estimated parameters associated with an equivalent model constituting a living tissue.

Claims

1. A skin condition estimating apparatus comprising:

impedance measuring means, and

skin condition estimating means,

wherein

the impedance measuring means has electrodes to make contact with a body and passes alternating currents of multiple frequencies through the body when the body is in contact with the electrodes to measure a contact impedance and an internal impedance which occur during the energization, and

the skin condition estimating means estimates a skin condition based on at least one of the contact impedance measured by the impedance measuring means and the internal impedance measured by the impedance measuring means.

2. The apparatus of claim 1, further comprising biological equivalent model associated parameter estimating means,

wherein

the biological equivalent model associated parameter estimating means estimates parameters associated with an equivalent model constituting a living tissue based on the frequencies of the currents passed by the impedance measuring means and the measured internal impedance, and

the skin condition estimating means estimates a skin condition based on at least one of the contact impedance measured by the impedance measuring means, the internal impedance measured by the impedance measuring means and the parameters estimated by the biological equivalent model associated parameter estimating means.

3. The apparatus of claim 2, wherein the parameters associated with the equivalent model constituting the living tissue are an extracellular fluid resistance, an intracellular fluid resistance, distributed membrane capacitance, a parallel combined resistance of the extracellular fluid resistance and the intracellular fluid resistance, and an angle formed by the real part axis and a straight line which connects the real part axis with an internal impedance measured when a vector locus corresponding to the internal impedances measured by the impedance measuring means using the alternating currents of multiple frequencies is drawn on the real part axis and the imaginary part axis based on the arc law representing a vector locus of impedances dependent on frequencies.

4. The apparatus of claim 3, wherein the biological equivalent model associated parameter estimating means estimates the extracellular fluid resistance, the intracellular fluid resistance and the distributed membrane capacitance by use of the following equation:

Z_B(=R_B+j×

X_B)=Re(Ri+½

×

π

×

f×

j×

Cm)
/Re+(Ri+½

×

π

×

f×

j×

Cm)

wherein Re represents an extracellular fluid resistance, Ri represents an intracellular fluid resistance, Cm represents distributed membrane capacitance, f represents a frequency, j represents an imaginary number, π

represents a pi, and Z_B represents an internal impedance (R_B represents a resistance component and X_B represents a reactance component).

5. The apparatus of claim 3, wherein the alternating currents of multiple frequencies are an alternating current of 50 kHz and an alternating current of 6.25 kHz.

6. The apparatus of claim 4, wherein the alternating currents of multiple frequencies are an alternating current of 50 kHz and an alternating current of 6.25 kHz.

7. The apparatus of claim 5, wherein the skin condition estimating means estimates at least one characteristic selected from the group consisting of moisture (or dryness), resilience (or swelling), texture and oiliness (or gloss) as a skin condition.

8. The apparatus of claim 6, wherein the skin condition estimating means estimates at least one characteristic selected from the group consisting of moisture (or dryness), resilience (or swelling), texture and oiliness (or gloss) as a skin condition.

9. The apparatus of claim 7, wherein the skin condition estimating means estimates moisture (or dryness), resilience (or swelling), texture and oiliness (or gloss) by use of the following equations:

Fw=a _w1 ×

R _C50 <sup>−

1</sup> +a _w2 ×

Re <sup>−

1</sup> +a _w3 ×

Ri/Re+a _w4
Ft=a _t1 ×

Re <sup>−

1</sup> +a _t2 ×

R _∞

<sup>−

1</sup> +a _t3 ×

Ri <sup>−

1</sup> +a _t4 ×

φ

+a _t5
Fs=a _s1 ×

φ

+a _s2 ×

X _B50 /R _B50 +a _s3
Ff=a _f1 ×

R _B6.25 /X _B6.25 +a _f2 ×

R _C5O /X _C50 +a _f3

wherein Fw represents moisture (or dryness), Ft represents resilience (or swelling), Fs represents texture, Ff represents oiliness (or gloss), R_C50 represents the resistance component of a contact impedance with an alternating current of 50 kHz, X_C50 represents the reactance component of the contact impedance with the alternating current of 50 kHz, R_B50 represents the resistance component of an internal impedance with an alternating current of 50 kHz, X_B50 represents the reactance component of the internal impedance with the alternating current of 50 kHz, R_B6.25 represents the resistance component of an internal impedance with an alternating current of 6.25 kHz, X_B6.25 represents the reactance component of the internal impedance with the alternating current of 6.25 kHz, Re represents an extracellular fluid resistance, Ri represents an intracellular fluid resistance, R_∞

represents a parallel combined resistance of the extracellular fluid resistance and the intracellular fluid resistance, φ

represents an angle formed by the real part axis and a straight line which connects the real part axis with an internal impedance measured with an alternating current of 50 kHz when an arc corresponding to the internal impedances measured by the impedance measuring means using the alternating currents of multiple frequencies is drawn on the real part axis and the imaginary part axis based on the arc law representing the relationship of impedances dependent on frequencies, and a_w1 to a_w4, a_t1 to a_t5, a_s1 to a_s3 and a_f1 to a_f3 represent coefficients (constants).

10. The apparatus of claim 8, wherein the skin condition estimating means estimates moisture (or dryness), resilience (or swelling), texture and oiliness (or gloss) by use of the following equations:

Fw=a _w1 ×

R _C50 <sup>−

1</sup> +a _w2 ×

Re <sup>−

1</sup> +a _w3 Ri/Re+a _w4
Ft=a _t1 ×

Re <sup>−

1</sup> +a _t2 ×

R _∞

<sup>−

1</sup> +a _t3 ×

Ri <sup>−

1</sup> +a _t4 ×

φ

+a _t5
Fs=a _s1 ×

φ

+a _s2 ×

X _B50 /R _B50 +a _s3
Ff=a _f1 ×

R _B6.25 /X _B6.25 +a _f2 ×

R _C5O /X _C50 +a _f3

wherein Fw represents moisture (or dryness), Ft represents resilience (or swelling), Fs represents texture, Ff represents oiliness (or gloss), R_C50 represents the resistance component of a contact impedance with an alternating current of 50 kHz, X_C50 represents the reactance component of the contact impedance with the alternating current of 50 kHz, R_B50 represents the resistance component of an internal impedance with an alternating current of 50 kHz, X_B50 represents the reactance component of the internal impedance with the alternating current of 50 kHz, R_B6.25 represents the resistance component of an internal impedance with an alternating current of 6.25 kHz, X_B6.25 represents the reactance component of the internal impedance with the alternating current of 6.25 kHz, Re represents an extracellular fluid resistance, Ri represents an intracellular fluid resistance, R_∞

represents a parallel combined resistance of the extracellular fluid resistance and the intracellular fluid resistance, φ

represents an angle formed by the real part axis and a straight line which connects the real part axis with an internal impedance measured with an alternating current of 50 kHz when an arc corresponding to the internal impedances measured by the impedance measuring means using the alternating currents of multiple frequencies is drawn on the real part axis and the imaginary part axis based on the arc law representing the relationship of impedances dependent on frequencies, and a_w1 to a_w4, a_t1 to a_t5, a_s1 to a_s3 and a_f1 to a_f3 represent coefficients (constants).