KR20170087806A - Method for evaluating skin flexibility or smoothness through the analysis of skin friction sound - Google Patents

Abstract

In the present invention, it is possible to objectively quantify the auditory change of the skin by the cosmetics by measuring the sound (fricative) generated in the skin.
Particularly, in the present invention, skin flexibility and softness can be diagnosed by one kind of evaluation of skin rub tone, so that cost and time efficiency of product development can be improved.

Description

[0001] The present invention relates to a method for evaluating skin softness or smoothness through skin friction sound analysis,

The present invention relates to a method of evaluating the softness or softness of skin through skin friction sound analysis.

By using cosmetics, users of cosmetics are supplied with moisture, nutrition, and the like, so that visual and tactile improvement can be expected by complementing defects such as wrinkles, dullness and roughness of skin surface. Because users of cosmetics are human, evaluation of efficacy of cosmetics is based on human emotions. Therefore, the cosmetics makers are quantifying the five senses perceiving human sensibility (visual, tactile, auditory, olfactory, and tastes) as objectively quantified values when evaluating the efficacy, thereby indexing the performance of the product.

The indicators used to verify the efficacy of cosmetics are roughness (softness), elasticity, moisture and brightness of the skin. The roughness (softness) of the skin is obtained by PRIMOS, which is a device for photographing skin images, and Replica, which is a device for lifting the skin pattern, and then the roughness index of the skin is analyzed by analyzing the roughness of the skin. The skin elasticity is measured using Cutometer MPA580, a device for measuring the elastic restoration of skin. This device calculates the elasticity index by using the property that the skin returns to its original state after the generation of negative pressure on the skin. Moisture content in the stratum corneum is measured using the Corneometer CM 825, which is based on the principle that the electrical resistance varies according to the water content. In addition, skin brightness is obtained by front-side photographing, and color analysis or colorimetric measurement is performed.

When measuring the skin-improving effect (roughness, elasticity, moisture content, brightness), one result per measurement equipment is calculated. Therefore, when it is necessary to check various skin-improving effects, it is necessary to measure each of the devices individually, which may reduce the efficiency in terms of time and cost.

In addition, the method of evaluating skin change has been mostly focused on the human sense of sight or tactile sense.

However, recently, studies on the auditory approach of the skin have been proceeding from the previous studies which reported that the sound generated from the skin changes according to the skin condition. To date, only the total size of the skin friction noise has been analyzed, and no research has been conducted to determine the cause of the change in the characteristics of the skin sound and to establish the evaluation method or to calculate the quantitative index. Due to the lack of such an evaluation method or indicator of skin sound, it is difficult to verify the auditory changes of the skin that cosmetic users can feel.

Therefore, it is urgent to develop an evaluation method and an index setting method capable of simultaneously measuring various characteristics of the skin and quantifying the characteristics of the skin through the change of auditory skin sound.

In order to solve the above-mentioned problems, the present invention aims at objectifying the performance before and after the use of cosmetics as an auditory index.

Specifically, the present invention quantifies how the sound of the skin changes by measuring and analyzing the rubbing noise (rubbing noise) before and after use of the cosmetic, and confirms the relationship between the rubbing sound and the skin condition improvement such as softness or softness of the skin have.

In other words, the object of the present invention is to create a new index capable of audibly measuring the efficacy of a product, based on the result of quantitative analysis of the skin characteristic by measuring the fricative occurring after applying the skin friction.

According to an embodiment of the present invention,

Storing and amplifying the fricative sound; And

Quantifying the amplified fricatives through frequency domain analysis, and diagnosing skin softness or softness.

Conventionally, the cosmetic can be verified only by changing the visual and tactile angles of the skin. However, in the present invention, it is possible to objectively quantify the auditory change of the skin by the cosmetics by measuring the sound (fricative) generated in the skin.

Conventionally, when performing a skin test for skin softness or softness, only one characteristic result per one measuring device was confirmed. However, in the present invention, since two characteristics can be diagnosed by one evaluation of the skin fricatives, the cost and time efficiency of product development can be improved.

1 is a graph showing a magnitude response and a phase response after a high-pass filtering pre-processing process is performed.
FIG. 2 is a graph showing a spectrum averaged by writing a hanning window function having a length of 1 second to a fricative measured during a friction time.
FIG. 3 is a 1/3 octave spectrum obtained by analyzing skin fricatives before and after using cosmetics.
4 is a schematic diagram of a rubber balloon model.
FIG. 5 is a graph quantifying the fricatives collected in the embodiment as a skin flexible index through a 1/3 octave analysis.
6 is a graph showing a result of evaluating skin flexibility using a cutometer.
FIG. 7 is a graph quantifying the fricatives collected in the embodiment as skin softness index through a 1/3 octave analysis. FIG.
8 is a graph showing the results of evaluating skin roughness by measuring irregularities on the surface of the skin with Primos.

The present invention relates to a method for producing a skin rinse,

Storing and amplifying the fricative sound; And

Quantifying the amplified fricatives through frequency domain analysis, and diagnosing skin softness or softness.

Hereinafter, the state evaluation method according to the present invention will be described in more detail.

In the present invention, "skin softness" means the extent to which the skin is changed by external stimuli. In the present invention, it can be said that the skin becomes more flexible when the deformation of the skin is increased by the unit force.

In general, the skin flexibility can be measured using a cutometer. When the external stimulus is defined as the sound pressure of the cutometer, the skin flexibility can be calculated by measuring the skin change corresponding to the tension when the tension is generated by the negative pressure of the cutometer. That is, when the skin is pulled by the sound pressure of the cutometer, the skin flexibility can be measured by the degree of pulling (R _O ).

In the present invention, "skin softness" means reduction of roughness of the skin.

Generally, the skin roughness can be measured by analyzing the degree of irregularity of the skin surface using the Ra index of Primos, a 3D skin imaging device.

In the present invention, an index capable of diagnosing the skin softness and / or skin softness can be provided by analyzing the friction sound of the skin (fricative tone), and thus it is possible to quantitatively calculate the improvement of the skin condition after application of the cosmetic Evaluation method can be provided.

The skin condition evaluation method according to the present invention

Generating a fricative sound on the skin (hereinafter, the first step);

Storing and amplifying the fricative (hereinafter, referred to as a second step); And

Quantifying the amplified fricatives through frequency domain analysis, and diagnosing softness or softness of the skin (hereinafter, referred to as a third step).

The first step in the present invention is a step of generating a rubbing sound on the skin.

The fricative sound means an output of skin vibration, sound, and friction generated when the rubbing pressure (friction) is transmitted to the skin, and may be referred to as a friction noise or a rubbing noise. Since the skin fricatives are affected by the structure of the inside of the skin and the roughness of the surface, the skin fricatives are also changed when there is a change in the skin condition. In accordance with the present invention, skin condition can be diagnosed through analysis of skin fricative using this point, and the present invention has been completed.

The skin rub can occur by rubbing the skin. The skin rubbing pressure, speed and time are not particularly limited. For example, the skin rub may be performed at a pressure of 40 to 46 Pa, a rate of 0.6 s / cycle, and a time of 10 seconds. Specifically, in the present invention, rubbing can be performed at a pressure of 43.7 ± 2 Pa, a speed of 0.6 s / cycle (= 1.67 Hz), and a time of 10 seconds. It is possible to generate a rubbing sound without damaging the skin at the above pressure, speed and time, and to obtain a rubbing sound to such an extent as to analyze skin flexibility and / or softness.

Since the rubbing speed is related to the change of the fricative, the friction speed after the cosmetic application may have a large influence on the change of the sound. Therefore, the speed is set as a control variable, and the sound change according to the skin condition can be observed while the speed is kept constant.

In the present invention, skin rubbing can be performed, for example, by using a commercially available rubbing tool or by using a hand. Specifically, a hand can be used to simulate a cosmetic use form. In one embodiment, in order to reduce the change in the fricative value according to the hand condition, the performed skin rub can be performed through a tester having a hand roughness value (Ra) of 25 to 30.

The second step of the present invention is a step of storing and amplifying the fricatives generated in the first step.

The generated fricatives can be recorded using, for example, a microphone (free-field type 1/2 inch, 20-20 kHz), and the fricatives can be amplified using an amplifier commonly used in the industry have.

 Also, in the present invention, recorded fricatives can be measured at a sampling frequency of 51.2 kHz using an A / D DAQ converter, Signal Express (National Instruments).

In one embodiment, an averaging operation may be performed to minimize the randomness of the measurements, i.e., the random error that occurs when rubbing. The factors of the random error include 1) a change in the friction method (speed, pressing force), and 2) the influence of noise other than the friction sound.

In the third step of the present invention, the fricative amplified in the second step is quantified through frequency domain analysis, and skin smoothness or softness is diagnosed.

In the present invention, the frequency domain analysis can utilize octave analysis or 1/3 octave analysis. Specifically, a fricative can be analyzed using a 1/3 octave analysis.

In one embodiment, a high-pass filtering pre-processing process may be performed to obtain an octave or 1/3 octave spectrum. This is because it is difficult to secure a signal-to-noise ratio due to dark noise in a frequency band of less than 100 Hz because the cutoff frequency of the anechoic chamber is 100 Hz, and spectrum distortion occurs due to reflected waves. In addition, the pre-treatment may be performed to remove a fundamental frequency component depending on a rubbing cycle, that is, how many times rubbing occurs in one second.

The octave analysis is a method of calculating the mean square value of the sound pressure for each band, and the 1/3 octave analysis is a method of finely dividing one band into three bands. The octave analysis is used for most noise analysis.

In the present invention, it is possible to quantify the fricatives as the skin softening index (dB _L ) through the above-mentioned 1/3 octave analysis, and diagnose the skin softness.

At this time, the skin flexibility index (dB _L ) may be a sound pressure level of less than 2000 Hz, specifically 125 to 1600 Hz. At 125 to 1600 Hz, the deformation of the skin due to the unit force is increased due to the reduction of the stiffness, so that as the flexible index value increases, the skin becomes more flexible.

Particularly, in the present invention, it is possible to measure the change in flexibility after application of cosmetics by comparing before and after softening index.

Further, in the present invention, the fricatives can be quantified to the skin softness index (dB _H ) through the 1/3 octave analysis, and the skin softness can be diagnosed.

At this time, the skin softness index (dB _H ) may be a negative value of the sound pressure level at 2000 Hz or more, specifically 2000 to 20000 HZ. At 2000 to 20000 Hz, the amplitude of the vibration decreases with time as the damping increases, so that the skin becomes softer. As the index value increases, the skin becomes smoother.

In particular, in the present invention, it is possible to compare softness indexes before and after cosmetics to measure softness changes after applying cosmetics.

Hereinafter, the 1/3 octave analysis method will be described in detail.

1 is a graph illustrating a magnitude response and a phase response after a high-pass filtering pre-processing process is performed. By applying FIR Butterworth filtering on the first measured data, it is possible to prevent the distortion of spectra due to the influence of the reflected wave of the anechoic chamber. It is possible to analyze the accurate skin rub noise by removing the fundamental frequency component according to the rubbing cycle.

2 is a graph showing a spectrum obtained by averaging a hanning window function having a length of 1 second with respect to fricatives measured during a friction time. In the averaging step, the influence of noise other than rubbing method or rubbing noise can be minimized in obtaining a 1/3 octave spectrum of skin rubbing noise.

라고 할 때, 평균화된 파워스펙트럼은 하기 식으로 계산될 수 있다. In one embodiment, a fricative is measured for 10 seconds and a hanning window function of length 1 second is written to obtain an averaged spectrum, which can be calculated as a square mean value of the sound pressure per 1/3 band. The power spectrum of the skin fric- tion (s (t)) measured for 10 seconds is obtained by taking a 1-second window function

, The averaged power spectrum can be calculated by the following equation.

<Formula 1>

That is, a 1/3 octave spectrum can be obtained through the sum of the subdivided energies in the averaged spectrum.

In the present invention, FIG. 3 is a 1/3 octave spectrum obtained by analyzing skin fricatives before and after using cosmetics. At this time, the fricative can be generated by performing a pressure of 43.7 ± 2 Pa, a speed of 0.6 s / cycle (= 1.67 Hz) and rubbing for 10 seconds.

As shown in FIG. 3, an inflection point where the energy of the low frequency region and the energy of the high frequency region are reversed in the vicinity of the 2000 Hz band on the spectrum (increase in the sound pressure level in the low frequency band below 2000 Hz after use of cosmetics, And the eeppressure level is reduced in the band). In the present invention, the region of less than 2000 Hz may be referred to as a low frequency band, and the region of 2000 Hz or more may be defined as a high frequency band.

In the present invention, 2000 Hz is defined as a characteristic frequency of skin because a uniform tendency is observed in the vicinity of 2000 Hz in the 1/3 octave analysis.

In the present invention, a rubber balloon model can be introduced to calculate the skin characteristic index using a specific frequency. 4 is a schematic diagram of a rubber balloon model in the present invention. Since the skin has acoustical properties such as rubber balloon, the rubber balloon model can be easily applied to the skin.

In the present invention, stiffness tends to be reduced by cosmetics in a region lower than the 2000 Hz frequency with 2000 Hz as a divergence point, thereby giving the skin a feeling of being softened. This is because if the deformation of the skin caused by the unit force is large, the skin becomes soft. The principle of skin flexibility index (dB _L ) can be calculated.

수식으로 표현할 수 있다. |Pm|²는 m 번째 1/3 옥타브 밴드의 A가중치 파워를 의미한다. 따라서 유연함 지표는 전처리 과정의 영향으로 1/3 옥타브 밴드기준으로 중심주파수 125 Hz(m=10)부터 16 kHz(m=21)까지의 A-가중치 SPL로 정의한다.The flexibility indicator

It can be expressed as a formula. | Pm | ² denotes the A weighting power of the mth one-third octave band. Therefore, the flexibility index is defined as the A-weighted SPL from the center frequency of 125 Hz (m = 10) to 16 kHz (m = 21) on the basis of 1/3 octave band due to the influence of the preprocessing process.

That is, the flexible index (dB _L ) means the sound pressure level in the range of less than 2000 Hz, specifically 125 to 1600 Hz, and the deformation of the skin due to the unit force is increased due to the reduction of the stiffness in this region. Therefore, since the skin becomes more flexible as the softness index value increases, the softness index before and after the make-up can be calculated and compared by the method according to the present invention to diagnose volume flexibility.

On the other hand, attenuation increases with use of cosmetics in the region higher than 2000 Hz frequency. This is because the skin will repeat the expansion and contraction in a complex shape in the region higher than 2000 Hz, and consequently, the effect of damping rather than stiffness can be deduced. Accordingly, the area of the skin becomes soft and the size of the friction sound becomes small after use of the cosmetic. The skin softness index (dB _H ) can be calculated by the above principle.

로 표현할 수 있다. |Pm|²는 m 번째 1/3 옥타브 밴드의 A가중치 파워를 의미한다. 부드러움 지표는 1/3 옥타브 밴드기준으로 중심주파수 2 kHz(m=22)부터 20 kHz(m=30)까지의 A-가중치 SPL에 음(negative)의 부호를 취한 값으로 정의될수 있다. 수식에 음의 부호를 취한 이유는 지표 값의 증가와 “부드러움” 물리적 현상간의 양의 상관관계를 나타내기 위해서이다.The softness index

. | Pm | ² denotes the A weighting power of the mth one-third octave band. The smoothness index can be defined as a value obtained by subtracting a negative sign from an A-weighted SPL from a center frequency of 2 kHz (m = 22) to 20 kHz (m = 30) on a 1/3 octave band basis. The reason for taking the negative sign in the formula is to show a positive correlation between the increase in the index value and the "soft" physical phenomenon.

That is, the softness index (dB _H ) means a negative value of the sound pressure level in the region of 2000 Hz or more, specifically 2000 to 20000 Hz. In this region, the amplitude of the vibration decreases with time, Is softened. Therefore, as the softness index value increases, the skin becomes softer, so that the softness index before and after the make-up can be calculated and compared by the method according to the present invention to diagnose skin softness.

Hereinafter, embodiments of the present invention will be described in detail to facilitate understanding of the present invention. However, the embodiments according to the present invention can be modified into various other forms, and the scope of the present invention should not be construed as being limited to the following embodiments. Embodiments of the invention are provided to more fully describe the present invention to those skilled in the art.

Example

Example 1. Flexibility index change after use of cosmetics

In 9 female subjects, skin friction sound was measured before and after cosmetic use in an artificial climate room (temperature 24 ~ 25 ℃, humidity 50 ~ 60% RH).

Cosmetics was applied ㎕ 2 per 1 cm ² area of the region for measurement. All the rubs were rubbed in a stationary state without interruption by applying the same force of 43.7 ± 2 Pa at a rubbing speed of 0.6 s / cycle (= 1.67 Hz), and rubbing occurred for 10 seconds per experiment. The position of the 1/2 "microphone was located parallel to the surface of the skin and the diaphragm surface of the microphone at a position 3 cm away from the skin.

The fricatives collected by the above method were quantified as a skin flexible index through a 1/3 octave analysis.

The results are shown in Fig.

As shown above, it can be confirmed that the value of skin flexibility index is increased after application of cosmetics.

In addition, skin flexibility was evaluated using a cutometer. Specifically, a cutometer was used to measure the extent to which the skin was pulled after applying negative pressure to the skin.

The results are shown in Fig.

As shown in FIG. 6, when the cosmetic is applied to the skin, flexibility of the skin is increased, and the result is similar to the result of the fricative analysis of the present invention.

In other words, it can be confirmed that skin flexibility can be measured through analysis of skin fricative.

Example 2: Softness index change after use of cosmetics

In 9 female subjects, skin friction sound was measured before and after cosmetic use in an artificial climate room (temperature 24 ~ 25 ℃, humidity 50 ~ 60% RH).

Cosmetics was applied ㎕ 2 per 1 cm ² area of the region for measurement. All the rubs were rubbed in a stationary state without interruption by applying the same force of 43.7 ± 2 Pa at a rubbing speed of 0.6 s / cycle (= 1.67 Hz), and rubbing occurred for 10 seconds per experiment. The position of the 1/2 "microphone was located parallel to the surface of the skin and the diaphragm surface of the microphone at a position 3 cm away from the skin.

The fricatives collected by the above method were quantified as a skin softness index through a 1/3 octave analysis.

The results are shown in Fig.

As shown above, it can be confirmed that the skin softness index value increases after application of the cosmetic.

In addition, skin roughness was evaluated by measuring the irregularities of the skin surface with Primos.

The results are shown in Fig.

As shown in FIG. 8, when the cosmetic is applied to the skin, the skin roughness value is decreased and the skin is softened.

The results were similar to those of the fricative analysis of the present invention.

In other words, it can be confirmed that skin softness can be measured through analysis of skin fricative.

Claims (9)

Generating a rubbing sound on the skin;
Storing and amplifying the fricative sound; And
Quantifying the amplified fricatives through frequency domain analysis, and diagnosing skin softness or softness.
The method according to claim 1,
A method for evaluating skin condition that rubs the skin for 10 seconds at a pressure of 40 to 46 Pa and a speed of 0.6 s / cycle to generate a rubbing sound.
3. The method of claim 2,
A method of evaluating skin condition by rubbing the skin using a hand.
The method according to claim 1,
A method for evaluating skin condition performed using a microphone for storing a fricative sound.
The method according to claim 1,
Frequency domain analysis is a 1/3 octave analysis.
6. The method of claim 5,
A skin condition evaluation method that quantifies fricatives as a skin softening index (dB _L ) through a 1/3 octave analysis and diagnoses skin softness.
The method according to claim 6,
Wherein the skin flexibility index (dB _L ) is a sound pressure level at 125 to 1600 Hz.
6. The method of claim 5,
A method for evaluating skin condition that quantifies fricatives as a skin softness index (dB _H ) through a 1/3 octave analysis and diagnoses skin softness.
9. The method of claim 8,
Wherein the skin softness index (dB _H ) is a negative value of the sound pressure level at 2000 to 20000 HZ.

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