JP7667107B2 - Tactile evaluation method - Google Patents

Description

The present invention relates to a technology for evaluating skin texture.

One method for evaluating the sensation of the skin surface involves applying a predetermined force to the evaluation target area of the skin to which a cosmetic has been applied, and measuring the mechanical response characteristics at that time (see, for example, Patent Document 1). Non-Patent Document 1 will be described later.

JP 2019-052858 A

Y. Tanaka, D. P. Nguyen, T. Fukuda, A. Sano, Proceedings of the IEEE World Haptics Conference, pp. 146-151 (2015)

In the case of Patent Document 1, a predetermined force is applied to the area of the skin being evaluated, and the mechanical response characteristics at that time are measured, but there is still room for research into how to use and analyze the measurement results.

The present invention was made in consideration of the above problems, and relates to a technology that makes it possible to measure physical quantities generated by moving a finger, palm, or measuring tool in contact with the skin of a subject in the direction of removal, and to extract and evaluate multiple types of feature quantities from the measured physical quantities. In this specification, "skin texture evaluation" refers to the evaluation of the tactile parameters of the skin surface of a subject for non-medical purposes, and includes evaluations that can be performed by evaluators who are not experts.

The present invention relates to a tactile evaluation method that includes an acquisition step of acquiring mechanical physical quantities over time that are generated by moving a finger, palm, or a measuring tool that is in contact with a skin surface or a skin surface to which a specified agent has been applied in a direction away from the skin surface, an extraction step of extracting multiple types of feature quantities, including one or more time-related feature quantities, from the physical quantities, and an evaluation step of evaluating the tactile parameters of the skin surface or the specified agent based on the multiple types of feature quantities.

The present invention also relates to a method for evaluating an agent, which includes an acquisition step of acquiring mechanical physical quantities over time that are generated by applying a specific agent to a skin surface and moving a finger, palm or measuring tool in contact with the skin surface to which the specific agent has been applied in a direction away from the skin surface; an extraction step of extracting multiple types of feature quantities, including one or more time-related feature quantities, from the physical quantities; and an evaluation step of evaluating the tactile parameters of the specific agent based on the multiple types of feature quantities.

The present invention also relates to a tactile evaluation system that includes a contact means that is brought into contact with a skin surface or a skin surface to which a specified agent has been applied, an acquisition means that acquires over time mechanical physical quantities that are generated by moving the contact means in a direction away from the skin surface or the skin surface to which a specified agent has been applied, an extraction means that extracts multiple types of feature quantities from the physical quantities, including one or more time-related feature quantities, and an evaluation means that evaluates the tactile parameters of the skin surface or the specified agent based on the multiple types of feature quantities.

The technology provided by this invention makes it possible to quantitatively evaluate the tactile sensation of a subject's skin surface.

This is an image diagram of a finger with a sensor attached touching the surface of a subject's skin. 1 is a flowchart showing a tactile evaluation method (this method) of the present embodiment. FIG. 1 is a conceptual diagram showing the relationship between the movement of a finger in contact with the skin surface and an agent on the skin surface. 13A is a waveform signal of an acquired physical quantity, and FIG. 13B is a waveform signal obtained by extracting a time domain effective for evaluation from the waveform signal of the acquired physical quantity. 11A and 11B are diagrams illustrating feature amounts extracted in extraction example 1. 1 is a graph showing the evaluation results of Evaluation Example 1. 13 is a graph showing the evaluation results of Evaluation Example 2. 13A and 13B are diagrams illustrating feature amounts extracted in extraction example 2. 13 is a graph showing the evaluation results of Evaluation Example 3. FIG. 2 is a block diagram of a tactile evaluation system 200.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
First, an overview of this embodiment will be described.
The tactile evaluation method of this embodiment (hereinafter, sometimes referred to as the present method) includes an acquisition step, an extraction step, and an evaluation step. The acquisition step is a step of acquiring mechanical physical quantities over time that are generated by moving a finger, a palm, or a measuring tool in contact with a skin surface or a skin surface to which a specific agent has been applied in a direction away from the skin surface. The extraction step is a step of extracting multiple types of feature quantities including one or more time-related feature quantities from the acquired physical quantities. The evaluation step is a step of evaluating the tactile parameters of the skin surface or the specific agent based on the multiple types of feature quantities extracted.

The present inventors have found that, in the past technology, for example, in Patent Document 1, a specific agent was applied to the skin, a specific force was applied to the evaluation target part of the skin, the mechanical response characteristics at that time were measured, and the feel of the skin to which the specific agent was applied was evaluated based on the measured value. That is, the evaluation was performed by focusing on the measured mechanical response characteristic value itself. However, as a result of the research, the inventors came to the insight that the feel of the subject's skin surface can be objectively evaluated by using multiple types of feature quantities that can be extracted from the measured mechanical physical quantities.
Therefore, in this method, mechanical physical quantities generated by moving a finger, palm or a measuring tool in a direction away from the skin surface, which is in contact with the skin surface or a skin surface to which a specified agent has been applied, are acquired over time, multiple types of feature quantities including one or more time-related feature quantities are extracted from the acquired physical quantities, and the tactile parameters of the skin surface or the specified agent are evaluated based on the multiple types of feature quantities extracted.

This method is explained in more detail below.

The skin surface in this method is the surface of human skin or artificial skin. The skin surface includes not only bare skin, but also the surface of skin on which a specific agent described below has been applied. That is, contacting the skin surface with fingers, palms, etc. includes not only direct contact of fingers, palms, etc. with bare skin, but also indirect contact with bare skin with fingers, palms, etc. through a coating film of a specific agent applied to the skin. The position of the human skin surface, that is, the part of the body, does not matter. When evaluating the tactile sensation of a specific agent, it is preferable to evaluate a part of the skin surface that does not have unevenness, such as warts or acne scars. This is because it is difficult to evaluate whether the tactile sensation when a finger touches the skin surface is due to the specific agent or the shape of the skin surface. However, for example, when it is desired to evaluate by tactile sensation whether the unevenness is covered (whether the skin surface has become flat) by applying a specific agent to uneven skin, this is not limited to this. It is desirable to determine the skin surface to be evaluated according to the conditions to be evaluated. Moreover, the artificial skin is an artificial imitation of the surface of the skin and has properties similar to those of human skin. In this embodiment, unless otherwise specified, the skin surface refers to the surface of the skin on the human face, particularly the area near the cheek.
Examples of the specified agent include external skin preparations to be applied to the skin surface, cosmetics, and sheet-type skin care cosmetics, such as lotions, milky lotions, creams, beauty serums, massage packs, lip balms, eye care sheets, mouth sheets, pack masks, sheet-type lotions, and sheet-type makeup removers; makeup cosmetics such as foundations, makeup bases, liquid foundations, oil-based foundations, powder foundations, concealers, control colors, eye shadows, blushers, lipsticks, lip glosses, lip liners, and body décolleté products; and ultraviolet ray protective cosmetics such as sunscreen milky lotions, sunscreen gels, and sunscreen creams, but are not limited to these.
The finger 20, palm, or measuring tool that is in contact with the skin surface is fitted with a sensor 30 shown in FIG. 1, which will be described in detail later. The finger 20 that is in contact with the skin surface may be at any position on the finger 20, but the finger pad is preferred because the tactile sensation is often confirmed with the finger pad. When checking the tactile sensation of the skin surface, not only the finger but also the entire palm may be in contact with the skin surface, so the palm may be in contact with the skin surface. The measuring tool is a tool that is in contact with the skin surface in the same way as the finger. The structure of the part of the measuring tool that is in contact with the skin surface is not limited, but by forming the part with artificial skin, it is possible to measure a physical quantity that is close to that when a person touches the skin surface with a finger or palm.

The direction away from the skin surface, which is the direction in which the finger 20, palm, or measuring tool is moved, is the outward direction approximately perpendicular to the skin surface. In this method, in order to evaluate the tactile sensation of the skin surface, the inward direction approximately perpendicular to the skin surface, i.e., the pressing direction, may be included, and the force may be changed depending on the purpose. Note that in this embodiment, moving the finger 20, palm, or measuring tool only in the horizontal direction on the skin surface, i.e., moving the skin surface solely in a rubbing manner, is not included. In other words, it is preferable to move the finger 20, palm, or measuring tool outward approximately perpendicular to the skin surface, and it may be moved outward approximately perpendicularly while moving horizontally to the skin surface.
Furthermore, when touching and moving a finger 20 or the palm of the hand on the skin surface, any of the following is acceptable: touching and moving one finger, touching and moving multiple fingers at the same time and moving multiple fingers at the same time, touching multiple fingers in sequence and moving them in sequence, touching the fingers and the palm at the same time and moving them at the same time, touching the fingers and then the palm.

A mechanical physical quantity is the amount of force that is mechanically generated, and examples include the magnitude of elastic force, the amount of current, voltage value, and vibration generated due to the displacement of the skin. The tactile sensation of the skin surface evaluated in this method is the tactile sensation caused by touching the skin surface with a finger or palm, such as a sticky feeling, a refreshing feeling, or a moist feeling. Thermal sensations such as coldness or warmth are not evaluated, so the physical quantities obtained do not include physical quantities that only show thermal characteristics.

The feature amount related to time is a feature amount related to time for a physical quantity acquired over time, and is, for example, a time from the rising edge of the physical quantity to the peak at which the intensity is maximum (first time), a time from the peak to the falling edge of the physical quantity (second time), a time which is a half-width of the maximum intensity of the physical quantity (third time), a time which is a total length from the rising edge to the falling edge (fourth time), a time from the rising edge of the physical quantity to the time when the physical quantity becomes an average value (fifth time), a time calculated using one or more of the first to fifth times (calculated time), etc. In addition to the feature amount related to time, the feature amount extracted from the acquired physical quantity includes, for example, the maximum intensity of the acquired signal, etc.
Extracting a feature quantity includes not only extracting a predetermined feature quantity from the acquired physical quantity, but also performing a predetermined calculation on the extracted feature quantity. Furthermore, the "intensity" and "maximum intensity" of a physical quantity refer to the absolute value of the acquired waveform signal (physical quantity) and the peak intensity at which that absolute value is maximum. Therefore, when the value of the acquired waveform signal (physical quantity) is negative as shown in Fig. 5 described later, the maximum intensity of the waveform signal (physical quantity) refers to the bottom point of the graph in the same figure.

The tactile sensation of the skin surface refers to the sensation felt when a finger in contact with the skin surface is moved away from the skin surface, and includes, for example, a sticky sensation, a refreshing sensation, a moist sensation, a sticky sensation, a moist sensation, a dry sensation, a firm sensation, a resilience sensation, a hard/soft sensation, a sticky sensation, a chewy sensation, a plump sensation, and the like, but is not limited to these sensations as long as they are felt when a finger in contact with the skin surface is removed from the skin surface. Here, the "sticky sensation" refers to the sticky sensation of a finger sticking to the skin surface when the finger is in contact with the skin surface. The "refreshing sensation" refers to the smooth, refreshing sensation of a finger not sticking to the skin surface when the finger is in contact with the skin surface. The "moist sensation" refers to the slightly moist and smooth sensation of a finger in contact with the skin surface. The "sticky sensation" refers to the sensation of a finger sticking to the skin surface when the finger is in contact with the skin surface. "Moisturizing" refers to the feeling of moderate moisture when a finger is touched to the skin surface. "Dry" refers to the feeling of dryness when a finger is touched to the skin surface. "Firm" refers to the feeling of the skin being taut and stiff when a finger is touched to the skin surface. "Elastic" refers to the feeling of bouncing back without sinking when a finger is touched to the skin surface. "Hard" refers to the degree to which the skin deforms when a finger is touched to the skin surface. "Sticky" refers to the feeling that a finger sticks to the skin surface when a finger is touched to the skin surface. "Soft" refers to the feeling that a finger sticks to the skin surface a little and then bounces back when a finger is touched to the skin surface. "Fluffy" refers to the feeling that a finger is slightly elastic and does not stick to the skin surface when a finger is touched to the skin surface, giving a refreshing feeling.
The tactile sensation of a specific agent refers to the tactile sensation of the agent itself when the specific agent is applied to the skin surface, or the tactile sensation of the skin surface to which the agent has been applied, such as sticky sensation, refreshing sensation, moist sensation, sticky sensation, moist sensation, dry sensation, firmness sensation, elasticity sensation, sticky sensation, bouncy sensation, plumpness, etc. Each sensation is as described above.
The tactile parameters include tactile sensations (e.g., sticky, refreshing, moist, viscous, moist, dry, taut, elastic, sticky, chewy, plump) and their degrees, as well as physical properties that produce these tactile sensations and their degrees. Here, physical properties that produce tactile sensations include the adhesion and moisture content of the skin surface, the elasticity and viscoelasticity of the skin surface or internal skin tissues, etc. "Adhesiveness" refers to the stickiness of the skin surface, which is caused by a specific agent, sebum, sweat, dirt, etc. "Moisture content" refers to moisture present on the skin surface, which is caused by a specific agent, sweat, etc. Also, it refers to the amount of moisture contained in the internal skin tissues (e.g., dermis). "Elasticity" refers to the hardness of the skin and affects the internal skin tissues (e.g., collagen). "Viscoelasticity" refers to the speed at which deformation progresses when force is applied to the skin, and affects the amount of moisture contained in the internal skin tissues (e.g., stratum corneum).
Evaluating tactile parameters refers to evaluating the tactile sensation of the skin surface or evaluating the physical properties that produce that tactile sensation. Evaluation does not only mean plotting the extracted feature quantities on a single or multiple axes and quantitatively evaluating them based on the plotted positions, but also includes evaluating the extracted feature quantities by comparing them with predetermined reference values and evaluating the correlation with the sensory quantity to be evaluated using a calibration curve or the like.

<Method of measuring physical quantities>
First, a method for measuring a physical quantity generated by moving a finger 20, a palm or a measuring tool (not shown) in contact with the face surface (skin surface) in a direction away from the face surface (skin surface) will be described with reference to FIG. 1.
1, the tactile sensation of the skin surface of a subject is measured using a calculation device 10, a finger 20, and a sensor 30. The calculation device 10 includes an input device such as a keyboard and a pointing device, a calculation processing device, a storage unit, and the like.
As shown in FIG. 1, a sensor 30 is attached to a finger 20. When the finger 20, particularly the finger pad (hereinafter, the finger pad is also referred to as the finger), touches the surface of the face (skin surface) and the touched finger 20 is moved, vibrations and deformations occur in the finger skin, and the sensor 30 detects these vibrations and deformations and outputs them as electrical signals to the computing device 10. Since the vibrations and deformations occurring in the finger skin differ depending on the tactile sensation, the electrical signals outputted depending on the tactile sensation also differ. This output electrical signal corresponds to the "mechanical physical quantity" of the present invention, and the electrical signal is acquired over time. Note that the sensor 30 may be, for example, a device described in the above-mentioned Non-Patent Document 1, but is not limited thereto. The sensor 30 may be a sensor (multi-axis sensor, force sensor) capable of acquiring the mechanical physical quantity generated by touching with the finger 20, for example, the acceleration and force generated by releasing the finger 20 that has been in contact with the surface of the face. Acquiring a physical quantity over time includes not only a mode in which the sensor 30 continuously acquires analog information (electrical signal in this embodiment) indicating the physical quantity over a predetermined time, but also a mode in which the sensor 30 acquires the physical quantity as digital information multiple times at short intervals such as on the order of milliseconds or sub-milliseconds. When the sensor 30 continuously acquires the physical quantity as analog information, it is preferable that the computing device 10 samples and discretizes the analog information at predetermined short intervals such as on the order of milliseconds or sub-milliseconds.
1, a finger 20 equipped with a sensor 30 is brought into contact with the surface of the face (skin surface) and the finger 20 is moved in a direction away from the surface of the face (skin surface) to perform a tapping motion. The finger 20 may repeat the tapping motion multiple times at a predetermined cycle.
In this embodiment, the sensor 30 is attached to the finger 20, and the finger 20 is brought into contact with the face surface (skin surface) and moved in a direction away from the face surface (skin surface) to measure the generated physical quantity, but when using a measuring tool, the sensor 30 is provided on a measuring tool (not shown) instead of the finger 20 in Fig. 1, and the measuring tool is brought into contact with the face surface (skin surface) and moved in a direction away from the face surface (skin surface), thereby making it possible to measure the generated physical quantity in the same manner. When the measuring tool is brought into contact with the face surface and moved for measurement, the movement of the measuring tool may be controlled using a predetermined device (not shown) so that the movement is uniform.

<Overview of tactile evaluation method>
The tactile evaluation method will be outlined below with reference to FIG.
The process (step S100) is a process of acquiring a mechanical physical quantity.
As shown in Fig. 1, the subject's facial surface (skin surface) is touched with a finger 20 equipped with a sensor 30. The touch is preferably performed by touching the facial surface with the finger 20 and moving it in a direction away from the facial surface, that is, a tapping motion. Whether or not the finger 20 is pressed into contact with the facial surface can be determined according to the purpose of evaluation. If the finger 20 is not pressed into contact, physical quantities necessary for evaluation based on information only on the skin surface can be obtained. Alternatively, the finger 20 may be tapped multiple times in the same manner to obtain mechanical physical quantities for multiple taps.

Step (step S110) is a step of extracting multiple types of feature quantities from the mechanical physical quantities acquired in step S100. Details will be described later, but the extracted feature quantities include time-related feature quantities. Furthermore, if the finger 20 is tapped multiple times on the face surface in step S100 and multiple mechanical physical quantities are acquired, any one tap may be identified and multiple types of feature quantities may be extracted from the mechanical physical quantities of that one tap, or multiple types of feature quantities may be extracted from an average physical quantity of the multiple mechanical physical quantities. In this embodiment, multiple types of feature quantities are extracted from the mechanical physical quantities of one tap.

Step (step S120) is an evaluation step that evaluates the tactile parameters of the skin surface or the specified agent using the multiple types of feature quantities extracted in step 110. Details will be described later, but if the specified agent has not been applied to the subject's facial surface, i.e., if it is bare skin, the tactile parameters of the skin surface are evaluated, and if the subject's facial surface has a specified agent applied, the tactile parameters of the specified agent or the tactile parameters of the skin surface to which the specified agent has been applied are evaluated.

<Mechanical physical quantities>
In this embodiment, the tactile parameters of the face surface (skin surface) to which a light agent, a moist agent, and a sticky agent are applied as predetermined agents are evaluated.
As shown in FIG. 3, when the finger 20 is brought into contact with the face surface 40 to which the predetermined agent 50 has been applied (see FIG. 3-(1)), and the finger 20 is moved in a direction away from the face surface 40, a liquid bridge is formed between the face surface 40 and the finger 20 by the predetermined agent 50 attached to the finger 20, generating a liquid bridge force (see FIG. 3-(2)), and tension is applied to the skin of the finger 20. Then, the liquid bridge force reaches its maximum (see FIG. 3-(3)), and then the liquid bridge by the predetermined agent 50 is separated from the finger 20, and the tension applied to the skin of the finger 20 is released (see FIG. 3-(4)). The deformation of the skin and the change in vibration caused by the change in tension generated in the skin of the finger 20 at this time are detected by the sensor 30, and a mechanical physical quantity is obtained by outputting a signal.
In this embodiment, the tactile parameters of a facial surface to which a specified agent has been applied are evaluated; however, even in the case of bare skin to which no specified agent has been applied, the tactile parameters of the skin surface (bare skin) to which no specified agent has been applied can be evaluated by analyzing the characteristics of substances such as sebum and sweat that exist between the finger 20 and the facial surface 40.

FIG. 4(a) shows the measurement waveforms obtained when each type of agent was applied, and FIG. 4(b) shows the measurement waveform in which a time region suitable for evaluation has been extracted from the waveform in FIG. 4(a).
4(a), the horizontal axis indicates the elapsed time from when finger 20 begins to be removed from face surface 40 until it is completely removed, and the vertical axis indicates the signal strength (voltage) acquired by sensor 30. Also, the signal acquired when a refreshing type agent is applied is indicated by a thin black line, and similarly, the signal acquired when a moisturizing type agent is applied is indicated by a thin line, and the signal acquired when a sticky type agent is applied is indicated by a thick black line.
The waveform in FIG. 4(a) represents the elapsed time from when finger 20 begins to be removed from the surface of the face until it is completely removed. Depending on the way finger 20 is moved, the start and end parts of the waveform contain signal waveforms that are not suitable for evaluation. Therefore, a signal waveform in a time domain suitable for evaluation, shown in FIG. 4(b), was extracted and evaluated.
Here, by analyzing the waveforms showing the physical quantities used in the evaluation shown in Fig. 4(b), it can be seen that when a sticky type agent is applied, the maximum intensity is greater than that of other types of agents. It can be seen that the maximum intensities of the moisturizing agent and the refreshing agent are closer to each other than that of the sticky type agent. It can also be seen that the time from when the signal intensity rises to when it reaches its maximum intensity differs depending on the type of agent.
In this way, the difference between the types of agents, i.e., the difference in texture, can be evaluated simply by evaluating the maximum intensity of the acquired physical quantity, but the evaluation of the maximum intensity alone does not allow, for example, evaluation of the change over time of the physical quantity. However, since it can be seen from Fig. 4(b) that there is a relationship between the difference in texture and the change over time of the physical quantity, the texture of the skin surface or a specific agent can be quantitatively evaluated by evaluating this relationship.

<Extraction Example 1 of Multiple Types of Feature Amounts>
In this embodiment, a plurality of types of feature amounts extracted from the acquired mechanical physical amount will be described.
Fig. 5 shows only the signal waveforms acquired when a sticky agent is applied, among the signal waveforms shown in Fig. 4. The extracted feature quantities will be described using the signal waveforms when a sticky agent is applied as an example.
In extraction example 1, the following feature amounts were extracted.
(1) The time from the rising edge of the acquired signal to the peak at which the signal has maximum intensity (referred to as the first time)
(2) The time from the peak to the fall of the acquired signal strength (referred to as the second time)
(3) The time at which the half-width of the maximum intensity of the acquired signal is reached (referred to as the third time).
(4) The total time from the rising edge to the falling edge of the acquired signal strength (referred to as the fourth time)
(5) The time from when the acquired signal strength rises until the signal strength reaches its average value (referred to as the fifth time)
(6) Maximum strength of the signal to be acquired (7) Time calculated using any one of the first time to the fifth time In extraction example 1, as shown in FIG. 5, the start point of the stable range of the signal to be acquired is specified as the "rising time" and the end point is specified as the "falling time". Here, an example of a method for specifying the "rising time" and the "falling time" in extraction example 1 will be described. A high-frequency filter is applied to the signal waveform of the physical quantity to be acquired to remove high-frequency noise. The maximum strength of the signal waveform from which high-frequency noise has been removed is selected. The times on both sides (start and end points) where the signal strength is substantially zero, which include the selected maximum strength, are obtained, and one period of tapping is extracted. Here, a threshold value is set in advance for the strength. The threshold value can be, for example, 10% of the maximum strength of the signal. Then, the moment when the strength first becomes lower than the predetermined threshold by scanning backward in time (towards the left in FIG. 5) from the point where the maximum strength occurs is set as the "rising time". Also, the moment when the strength first becomes lower than the predetermined threshold by scanning forward in time (towards the right in FIG. 5) from the point where the maximum strength occurs is set as the "falling time". Each feature amount was extracted based on the "rising edge" and "falling edge" thus specified. Note that the threshold value was set to 10% of the maximum intensity, but the ratio to the maximum intensity is not limited to this value. The threshold value may be set as a fixed value instead of a ratio to the maximum intensity.
Furthermore, in Extraction Example 1, the feature amounts shown in (1) to (7) above are extracted, but are not limited to these. Examples include feature amounts of time and intensity related to the timing of change over time of the acquired signal, such as the time from when the acquired signal intensity becomes the average value until it peaks, the ratio of the first time to the second time, the ratio of the fifth time to the time from when the acquired signal intensity becomes the average value until it peaks, and the average intensity of the acquired signal.

An evaluation performed using the feature amounts extracted in Extraction Example 1 will be described.
(1) Evaluation Example 1
Among the features extracted in extraction example 1, the evaluation was performed based on the fourth time and the ratio between the third time and the fourth time. That is, the evaluation was performed using a feature related to time for all of the multiple types of features used in the evaluation of the tactile sensation. The third time and the fourth time are feature values that affect the spread of a predetermined agent applied to the face surface when the touched finger 20 is moved in a direction away from the face surface. In this embodiment, the ratio between the third time and the fourth time is calculated as (fourth time-third time)/fourth time, but this is not limited thereto, and any ratio between the third time and the fourth time can be calculated, for example, third time/fourth time.
Table 1 shows the feature amounts extracted from the signal waveforms acquired when a specific agent was applied.

FIG. 6 is a graph plotting the fourth time on the horizontal axis and the ratio between the third time and the fourth time on the vertical axis for the feature quantities in Table 1. The larger the ratio, the sharper the peak of the maximum intensity of the acquired physical quantity, and the better the type of agent spreads. As is clear from FIG. 6, it was found that the spread of the agent differs depending on the type of a given agent. In particular, the sticky type has a shorter fourth time and a larger ratio than the other types of agents. Also, for example, in the waveform of the acquired physical quantities shown in FIG. 4, it can be seen that the timing at which the agent leaves the finger 20 is close for the moist type and the sticky type, but the spread of the moist type agent is closer to the spread of the refreshing type agent.
In this way, when evaluation is performed based on multiple types of feature quantities including time-related feature quantities extracted from the acquired physical quantities, it is possible to evaluate the characteristics of the agent associated with changes over time that cannot be determined by only evaluating the acquired physical quantities, and therefore it is possible to quantitatively evaluate the tactile sensation of the skin surface or a specified agent. In the case of feature quantities related to strength, the values extracted vary depending on the way the finger 20 touches the skin surface, such as the tapping speed and tapping strength. On the other hand, when multiple types of feature quantities used to evaluate the tactile parameters are all time-related feature quantities, the values are values that exclude such variations, and therefore evaluation can be focused on the characteristics of the skin surface or agent. As a result, it is possible to quantitatively evaluate the tactile parameters of the subject's skin surface or the tactile parameters of a specified agent.

In the above-mentioned evaluation example 1, the evaluation was performed based on the fourth time and the ratio between the third time and the fourth time. That is, the evaluation was performed based on a plurality of different types of time terms, but other time terms may be used. For example, the evaluation may be performed based on the second time and the ratio between the third time and the second time. At the second time, a vibration occurs when a predetermined agent 50 attached to the finger 20 is separated from the finger 20 and the agent 50 that was spread on the skin of the finger 20 returns. The vibration generated at this time is a value that is greatly affected by the difference in agent and is not easily affected by the way the finger 20 is moved (the speed of movement), so it is a feature suitable for evaluating the tactile sensation. Therefore, the evaluation may be performed based on the second time and the ratio between the third time and the second time. Even when the evaluation is performed based on the second time and the ratio between the third time and the second time, the tactile parameter is evaluated using a plurality of types of feature amounts related to time.

(2) Evaluation Example 2
The waveforms showing the time-dependent changes in physical quantities shown in Fig. 4 were regarded as histograms (called pseudo histograms), and the skewness and kurtosis of each pseudo histogram were calculated and evaluated. The feature quantities calculated from each pseudo histogram are shown in Table 2.

Figure 7 is a graph of the kurtosis for each agent shown in Table 2. From Figure 7, it can be seen that the kurtosis of the sticky type agent is larger than that of the other types of agents, and therefore the physical quantity of the sticky type agent has a sharp peak.
In this way, by performing an evaluation based on multiple types of features including time-related features extracted from the acquired physical quantities, it is possible to evaluate the characteristics of the agent that change over time, which cannot be determined by only evaluating the acquired physical quantities, and therefore it is possible to quantitatively evaluate the tactile parameters of the skin surface or a specified agent.

<Extraction Example 2 of Multiple Types of Feature Amounts>
Fig. 8 shows only the signal waveforms acquired when a sticky agent is applied, among the signal waveforms shown in Fig. 4. The extracted feature quantities will be described using the signal waveforms when a sticky agent is applied as an example.
In extraction example 2, the following feature amounts were extracted.
(1) The time from the rising edge of the acquired signal to the peak at which the signal has maximum intensity (referred to as the first time)
(2) the maximum strength of the acquired signal; (3) the average strength of the physical quantity; and (4) the total time from the rising edge to the falling edge of the acquired signal strength (referred to as the fourth time).
(5) The time from when the acquired signal strength rises until the signal strength reaches its average value (referred to as the fifth time)
An example of a method for identifying the "rising time" and the "falling time" in the extraction example 2 will be described. A high-frequency filter is applied to the signal waveform of the physical quantity to be acquired to remove high-frequency noise. The maximum intensity in the signal waveform from which the high-frequency noise has been removed is selected. The times on both sides (start point and end point) where the signal intensity becomes zero, including the selected maximum intensity, are obtained, and one period of tapping is extracted. That is, the moment when the signal intensity crosses zero by scanning backward in time from the point where the maximum intensity occurs (towards the left in FIG. 8) is defined as the "rising time". Also, the moment when the signal intensity crosses zero by scanning forward in time from the point where the maximum intensity occurs (towards the right in FIG. 8) is defined as the "falling time". Based on the "rising time" and "falling time" thus identified, each feature amount was extracted.
The above feature quantities are only those used in the following evaluation example 3, and it goes without saying that other feature quantities may be extracted depending on the evaluation content. As in extraction example 1, one tapping cycle may be used, in which the start point of the stable range of the acquired signal is specified as the "rising time" and the end point as the "falling time". A method for specifying the "rising time" and the "falling time" may be determined according to the signal waveform of the acquired physical quantity, the evaluation content, etc. by tapping multiple times.

(3) Evaluation Example 3
Among the feature amounts extracted in Extraction Example 2, the evaluation was performed based on the difference between the first time and the fifth time and the maximum peak intensity as an absolute value of the acquired signal. In this embodiment, the values extracted in Extraction Example 2 (1) to (5) are used to plot the values calculated as follows on the horizontal axis and the maximum intensity of the acquired signal (maximum intensity as an absolute value) on the vertical axis in a graph shown in FIG.
A method for calculating the horizontal axis value in this embodiment will be described.
First, the difference between the first time and the fifth time is obtained. At this time, the sign is left as it is. That is, as is clear from FIG. 4, the difference between the first time and the fifth time is a positive value for the waveform signal of the sticky type agent and the moist type agent, and the difference between the first time and the fifth time is a negative value for the waveform signal of the refreshing type agent. Then, by dividing the difference between the first time and the fifth time by the fourth time, a standardized value that does not depend on the period specified as the analysis target is obtained. Therefore, it is possible to evaluate by a value that does not affect the touching manner (tapping timing) of the skin surface of the finger 20. It is not necessary to divide the difference between the first time and the fifth time by the fourth time, and it is sufficient if the difference between the first time and the fifth time is the value on the horizontal axis.
As is clear from Fig. 9, the vector quantity is clearly different depending on the type of agent. For the sticky agent and the moist agent, the difference between the first time and the fifth time is a positive value, so the signal intensity becomes the average value before the signal reaches the maximum intensity, and for the refreshing agent, the signal intensity becomes the average value after the signal reaches the maximum intensity. Therefore, it is difficult to evaluate the difference between the refreshing agent and the moist agent based on only the maximum intensity of the acquired physical quantity, but by including the feature quantity related to time in the evaluation items, a more objective evaluation is possible.

In this way, by extracting multiple types of features from the acquired mechanical physical quantities and evaluating the tactile parameters of the skin surface or a specified agent based on the extracted features, it is possible to quantitatively evaluate the tactile parameters of the skin surface or a specified agent.

<Evaluation method of the agent>
In the above-mentioned tactile evaluation method, multiple types of features including one or more time-related features are extracted from physical quantities acquired over time, and the tactile parameters of the skin surface or a specified agent are evaluated. The specified agent is applied to the skin surface, and the applied skin surface is tapped with a finger 20, the palm of the hand, or a measuring tool, and the same process is performed to evaluate the tactile parameters of the applied agent, that is, the method can also be used as an agent evaluation method for evaluating the agent.

<About the tactile evaluation system>
The tactile evaluation system 200 will be described with reference to FIG.
The tactile evaluation system 200 in this embodiment is composed of a contact means 110, an acquisition means 120, an extraction means 130, and an evaluation means 140. The system also includes an information processing terminal 100 capable of executing various processes, and the information processing terminal 100 is equipped with the extraction means 130 and the evaluation means 140. The information processing terminal 100 is equipped with input devices such as a keyboard and a pointing device, a processing unit, a storage unit, etc. The information processing terminal 100 is also preferably equipped with a display means 150 (display device) and a sound output means 160 (speaker), but these may be provided outside the information processing terminal 100 and connected via a network.

The contact means 110 is a finger 20, a palm, or a measuring tool that is brought into contact with the surface of the face.
The acquiring means 120 is a means for acquiring, over time, a mechanical physical quantity generated by moving the finger 20, using the sensor 30 attached to the finger 20 shown in Fig. 1. The mechanical physical quantity (electrical signal) acquired by the sensor 30 is configured so as to be acquired by the information processing terminal 100 via a network line, a medium, etc.
The extraction means 130 is a means for extracting a plurality of types of feature quantities including a feature quantity related to time from the mechanical physical quantity (electrical signal) acquired by the acquisition means 120. The plurality of types of feature quantities to be extracted are the same as those described above in the tactile evaluation method.
The evaluation means 140 is a means for evaluating the tactile parameters of the skin surface or the predetermined agent using the feature quantities extracted by the extraction means 130. If the predetermined agent has not been applied to the subject's facial surface, i.e., if the subject's facial surface is bare skin, the tactile parameters of the skin surface are evaluated, and if the subject's facial surface has been applied with the predetermined agent, the tactile parameters of the predetermined agent are evaluated. The evaluation contents are the same as those described above in the tactile evaluation method. It is preferable that the evaluation results by the evaluation means 140 are made easily comprehensible by the evaluator using the display means 150 and/or the audio output means 160.
The display means 150 is a means for displaying the evaluation results by the evaluation means 140, for example, the graphs shown in Fig. 6, Fig. 7, and Fig. 9. In addition to the graphs shown in Fig. 6, Fig. 7, and Fig. 9, the display means 150 may display characters or aspects expressing the corresponding tactile sensation (corresponding to the tactile sensation) to make it easier for the evaluator to visually grasp. In the case of characters, stickiness is represented by displaying characters expressing or evoking stickiness, such as "sticky,""sticky," or "sticky." In the case of aspects, stickiness may be represented by displaying, for example, a sticky skin image or an image of a sticky state like glue.
The sound output means 160 may output a sound representing the corresponding tactile sensation or an imagining sound (a sound corresponding to the tactile sensation) based on the evaluation result by the evaluation means 140. For example, a plurality of predetermined synthetic sounds may be prepared, and the type, output time, and output volume of the synthetic sound may be determined according to the feature amount extracted in this embodiment. Also, a predetermined sound conversion function may be stored in advance, and the feature amount extracted in this embodiment may be input to the sound conversion function, thereby outputting a synthetic sound corresponding to the feature amount.

<Modification>
The present invention is not limited to the above-described embodiment, and various modifications and improvements are possible.

In this embodiment, the tactile parameters of a facial surface to which a specific agent has been applied or the tactile parameters of the agent were evaluated. Using a similar method, the tactile parameters of a skin surface (bare skin) to which a specific agent has not been applied can also be evaluated. Substances such as sebum and sweat adhere to the skin surface (bare skin). When a finger 20 is brought into contact with the skin surface (bare skin) and moved in the direction of removal, the tactile parameters of the skin surface (bare skin) can be evaluated by analyzing the characteristics of the substances adhering to the skin surface.

In the above-mentioned evaluation example 1, the evaluation was performed based on the fourth time and the ratio between the third time and the fourth time. That is, the evaluation was performed based on a plurality of different types of time terms, but other time terms may also be used. For example, the first time and the fifth time may be extracted, and the evaluation may be performed based on the difference between the first time and the fifth time. Since the first time and the fifth time are also times that are affected by the way the specified agent spreads, as in the case of using other times, it is possible to evaluate the characteristics of the agent associated with changes over time that cannot be understood by only evaluating the acquired physical quantity, and therefore it is possible to quantitatively evaluate the tactile parameters of the skin surface or the specified agent.

In the above-mentioned evaluation example 2, the evaluation was performed using the kurtosis calculated from the pseudo histogram, but the evaluation may also be performed using the skewness calculated from the pseudo histogram. Since the position of the pseudo histogram peak is characteristic depending on the type of agent, the tactile parameters can be evaluated by evaluating the position of the pseudo histogram peak using the skewness.

The "third time" among the multiple types of feature quantities extracted in the above-mentioned extraction example 1 is set to the half-width of the maximum intensity of the signal to be acquired. In this embodiment, the half-width is set to the time length in which the signal has a value of 50% or more of the maximum intensity as shown in FIG. 5, but is not limited to this, and the half-width may be set to the time length in which the signal has a value of 25% or more, or may be set to the time length in which the signal has a value of 75% or more. In other words, the "half-width" described in this embodiment is an index indicating the extent of the spread of the peak that is the maximum intensity in the waveform showing the change over time of the acquired physical quantity, and is not limited to the time length in which the peak has an intensity of 50% or more of the maximum intensity. When setting the half-width, it is arbitrary to determine what percentage of the intensity of the peak's maximum value should be included in the peak. If this percentage is too low, the base of the peak will be excessively included, so 25% or more is preferable.

In this embodiment, the tactile parameters are evaluated by displaying a graph, displaying a display mode according to the evaluation content, and outputting a sound according to the evaluation content. However, the present invention is not limited to this. For example, a vibrator (vibration output means (not shown)) that generates a predetermined vibration may be provided, and the vibrator may be vibrated in a vibration mode according to the evaluation result. In this way, the evaluated tactile parameters can be experienced by people other than the person who actually touched the skin surface, making it easier to understand the evaluation results.

In this embodiment, when the finger 20 is brought into contact with the facial surface, the touch of the skin surface is measured without pressing the finger 20 against the facial surface. However, this is not limited to the above, and the finger 20 may be brought into contact with the facial surface in a direction substantially perpendicular to the skin surface, i.e., the direction of pressing, and it is sufficient to determine how the finger 20 is brought into contact with the facial surface depending on the content to be evaluated. By including the pressing direction, an evaluation can be performed that includes information about the inside of the skin.

In this embodiment, the tactile parameters of the skin surface were measured after the application of the specified agent, but measurements may be taken multiple times, for example, immediately after application of the specified agent, 30 minutes later, and one hour later. By taking measurements multiple times in this way and comparing the results, it is possible to understand the changes in the tactile parameters of the skin surface over time after application of the specified agent.

In this embodiment, a specific agent is applied to the surface of the face, and the tactile sensation of the skin surface is measured. However, the present invention is not limited to this. For example, a skin care agent such as a mask sheet soaked in a specific agent may be placed (attached) on the surface of the face and its tactile parameters may be measured. In this way, the tactile parameters of an agent placed (attached) on the surface of the face during use can be evaluated.
When using cotton or a sheet soaked in lotion or makeup remover, the cotton or sheet soaked in the agent may be wrapped around a finger. In this case, the finger wrapped around the cotton or sheet soaked in the agent is brought into contact with the surface of the face, a predetermined physical quantity is obtained over time, and an evaluation similar to that described above is performed, so that the tactile parameters when using the cotton or sheet soaked in the agent can be evaluated. Even if the cotton or sheet is not soaked in a predetermined agent, the tactile parameters when using the oil blotting paper or paper can be evaluated by bringing a finger wrapped around oil blotting paper, paper, or film into contact with the surface of the face, obtaining a predetermined physical quantity over time, and performing an evaluation similar to that described above. Similarly, when using a puff with face powder or foundation attached, the puff can be brought into contact with the surface of the face with a finger and a similar evaluation is performed, so that the tactile parameters when using the puff can be evaluated.
The tactile sensation when using the agent includes the state in which the agent is applied to the surface of the face, as well as the tactile sensation when, for example, the agent is taken with a finger (the agent is placed on the finger) and the finger is brought into contact with the surface of the face. The tactile parameters when applying the agent with a finger can also be evaluated by bringing the finger on which the agent is placed into contact with the surface of the face, acquiring predetermined physical quantities over time, and carrying out evaluations similar to those described above.

Reference Signs List 10 Calculation device 20 Finger 30 Sensor 40 Skin surface 50 Agent 100 Information processing terminal 110 Contact means 120 Acquisition means 130 Extraction means 140 Evaluation means 150 Display means 160 Audio output means 200 Tactile sensation evaluation system

Claims (12)

an acquisition process for acquiring mechanical physical quantities over time that are generated by contacting a finger, palm or measuring tool provided with a sensor with a skin surface or a skin surface to which a specific agent has been applied, and moving the finger, palm or measuring tool that has been contacted with the skin surface or the skin surface to which the specific agent has been applied in a direction away from the skin surface;
an extraction step of extracting a plurality of types of feature quantities including one or more feature quantities related to time from the physical quantity;
The feature amount is
A first time from a rise time of the physical quantity to a peak time having a maximum intensity,
a second time from the peak time to the fall time of the physical quantity;
a third time, which is a half-width of the maximum intensity of the physical quantity; or a fourth time, which is a total length from the rising edge to the falling edge;
Including any of the following:
The tactile evaluation method further comprises an evaluation step of evaluating the tactile parameter of the skin surface or the specified agent based on the relationship between the result of mutually calculating at least two of the first time to the fourth time, the result being statistically correlated with the tactile parameter, and the tactile parameter. The tactile evaluation method according to claim 1, characterized in that in the evaluation step, the tactile parameters of the skin surface or the specified agent are evaluated based on the ratio between the fourth time or the second time and the third time. the plurality of types of feature quantities further include a fifth time indicating a time from the rising edge of the physical quantity until the physical quantity becomes an average value,
The tactile evaluation method according to claim 1 , wherein in the evaluation step, a tactile parameter of the skin surface or the specified agent is evaluated based on a difference time between the first time and the fifth time. 3. The tactile evaluation method according to claim 1 , wherein the plurality of types of feature quantities used in the evaluation of the tactile parameters are all feature quantities related to time. The tactile evaluation method according to claim 3 , wherein the plurality of types of feature quantities used in the evaluation of the tactile parameters include a feature quantity related to the intensity of the physical quantity. the feature quantity related to the intensity of the physical quantity is the maximum intensity,
The tactile evaluation method according to claim 5 , wherein in the evaluation step, a tactile parameter of the skin surface or the specified agent is evaluated based on the difference time between the first time and the fifth time and the maximum intensity. an acquisition process for acquiring mechanical physical quantities over time that are generated by contacting a finger, palm or measuring tool provided with a sensor with a skin surface or a skin surface to which a specific agent has been applied, and moving the finger, palm or measuring tool that has been contacted with the skin surface or the skin surface to which the specific agent has been applied in a direction away from the skin surface;
an extraction step of extracting a plurality of types of feature quantities including one or more feature quantities related to time from the physical quantity;
In the extraction step, a skewness or a kurtosis of a waveform indicating a change over time in the physical quantity acquired in the acquisition step is calculated;
The tactile evaluation method further comprises an evaluation step of evaluating tactile parameters of the skin surface or the specified agent based on the skewness or the kurtosis. A prescribed agent is applied to the skin surface,
an acquisition process for acquiring mechanical physical quantities over time that are generated by bringing a finger, palm or measuring tool provided with a sensor into contact with the skin surface to which the specified agent has been applied , and moving the finger, palm or measuring tool that has been brought into contact with the skin surface to which the specified agent has been applied in a direction away from the skin surface;
an extraction step of extracting a plurality of types of feature quantities including one or more feature quantities related to time from the physical quantity;
The feature amount is
A first time from a rise time of the physical quantity to a peak time having a maximum intensity,
a second time from the peak time to the fall time of the physical quantity;
a third time, which is a half-width of the maximum intensity of the physical quantity; or a fourth time, which is a total length from the rising edge to the falling edge;
Including any of the following:
The method for evaluating the tactile sensation of an agent further includes an evaluation step of evaluating the tactile parameter of the specified agent based on the relationship between the tactile parameter and a result of calculating at least two of the first time to the fourth time, the result being statistically correlated with the tactile parameter. an acquisition means for acquiring a mechanical physical quantity generated over time by bringing a contact means having a sensor into contact with a skin surface or a skin surface to which a predetermined agent has been applied, and moving the contact means in a direction away from the skin surface or the skin surface to which the predetermined agent has been applied;
an extraction means for extracting a plurality of types of feature quantities including one or more feature quantities related to time from the physical quantity;
The feature amount is
A first time from a rise time of the physical quantity to a peak time having a maximum intensity,
a second time from the peak time to the fall time of the physical quantity;
a third time, which is a half-width of the maximum intensity of the physical quantity; or a fourth time, which is a total length from the rising edge to the falling edge;
Including any of the following:
The tactile evaluation system further comprises an evaluation means for evaluating the tactile parameter of the skin surface or the specified agent based on the relationship between the result of calculating at least two of the first time to the fourth time, the result being statistically correlated with the tactile parameter, and the tactile parameter. Further comprising an audio output means,
10. The tactile evaluation system according to claim 9, wherein the evaluation means causes the audio output means to output a sound corresponding to the tactile parameter of the evaluated skin surface or the predetermined agent . Further comprising a display means,
11. The tactile evaluation system according to claim 9, wherein the evaluation means causes the display means to display a display mode corresponding to the tactile parameters of the evaluated skin surface or the predetermined agent . Further comprising vibration output means,
12. The tactile evaluation system according to claim 9 , wherein the evaluation means causes the vibration output means to output vibrations corresponding to tactile parameters of the evaluated skin surface or the predetermined agent .

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