Patent Description:
Cosmetic hair treatments, that is, bleaching, perming, straightening, etc. are known to slightly alter the hair surface properties, by modifying the orientation (lifting up) of the cuticular scales of the hair, thereby increasing the frictional force encountered by, for example, a hair professional when pinching the hair and sliding it between his/her fingers. In order to regain smoothness, the hair having an increased frictional force, needs to be appropriately treated according to its degree of smoothness, and for this purpose it is important to measure the frictional properties of the surface of the hair. Also, the measurement of the frictional properties is important in order to know to what extent the treated hair has recovered its smoothness. Furthermore, the measurement of the frictional properties is also useful in the laboratory for specifying frictional homogeneity or heterogeneity of the hair.

Usually, such frictional properties are roughly determined by the feel of the hair. However, if a higher measurement accuracy is required, a stick-like measuring device with a sensor unit mounted at the tip thereof is used. Measurement of the frictional properties of the hair, for example, hair growing on the scalp, using a conventional device is carried out by pressing the sensor unit of the device against the hair and moving the device downward from the top of the head at a constant speed. At that time, the sensor unit measures the load applied to the unit by the operator, i.e., the pressing force and the frictional force generated during this movement. The frictional properties of the hair, in particular, the frictional coefficient thereof, is calculated by dividing the frictional force by the pressing force.

A disadvantage of the conventional device is that it is difficult to constantly apply a constant pressing force to the hair, in other words, to control the pressing force during measurement. This is because the pressing force is exclusively applied to the hair depending on the force sensation of the operator. Furthermore, when measuring the frictional properties of the hair growing on the scalp, since the orientation of the device continuously changes during measurement, it is more difficult to constantly apply a constant pressing force to the measurement target. For this reason, it is not possible to realize high repeatability and reproducibility by using the conventional device.

Examples of prior art related to the present invention are disclosed in the following publications. <CIT> discloses a hair damage measurement system by a frequency fluctuation analysis on a hair comb. <CIT> discloses a hair damage measurement system with a microphone on a hair comb. <CIT> discloses a hair characteristic evaluation system with a piezoelectric sensor (PVDF film) on a hair comb. <CIT> discloses a hair brush having a control unit which is controlled according to friction coefficient detected by friction sensor to change output of ventilation unit and heating unit.

In view of the above, an object of the present invention is to provide a novel device for measuring the frictional properties of natural or synthetic fibers which can overcome the disadvantage of the prior art device. In particular, an object of the present invention is to provide a novel device for measuring the frictional properties of fibers which can apply a constant load to the fibers whose frictional properties are to be measured during the measurement, thereby realizing high repeatability and reproducibility.

In order to achieve this object, the present invention provides a device according to claim <NUM>.

The device according to the present invention configured as described above includes a nipping system that can constantly apply a constant pressing force (load) to the fibers whose frictional propertieptusions are to be measured. Therefore, the frictional forces arising when the device is being moved relative to the fibers sandwiched between the sensor unit and the nipping member in a direction crossing the longitudinal axis of the base member can be measured in a state in which a constant pressing force is applied to the fibers by this nipping system. Thus, the device according to the present invention is operator-independent. That is, the device according to the present invention can eliminate variations in the pressing force applied to the fibers, so that it becomes possible to measure the frictional properties of the fibers accurately and with high repeatability and reproducibility. Furthermore, in the device according to the present invention, unlike conventional fiber-pressing type devices, the frictional properties are measured only for fibers loaded in the nipping system. Therefore, the number of fibers to be measured can be freely controlled.

The term "fibers" as used herein is intended to encompass naturally-derived fibers such as hair, wool, silk, and cotton, or synthetic fibers such as nylon, polyester, polyamide, and carbon. In addition, the term "fibers" as used herein is intended to encompass woven or knitted fibers such as ropes, cables, cloth, and paper.

According to one preferred aspect of the present invention, the nipping member may be connected to the base member such that the one end of the nipping member is separated from the sensor unit by pressing the other end of the nipping member which is present on the side opposite to the one end of the nipping member. This is useful for enhancing the operability of the device.

According to the present invention, the nipping member comprises first and second protrusions on its face facing the sensor unit at the one end of the nipping member, and the first and second protrusions are arranged such that the sensor unit is located between the first protrusion and the second protrusion when the nipping member is closed to apply the pressing force on the fibers sandwiched between the sensor unit and the nipping member. In this aspect, the first and second protrusions serve as a guide for the fibers (in particular a bundle of the fibers), which serves to ensure that the fibers are certainly positioned within the measurement space between the sensor unit and the nipping member.

According to one preferred aspect of the present invention, at least one spring may be interposed between the base member and the nipping member, and the spring may function to apply a constant pressing force on the fibers sandwiched between the sensor unit and the nipping member. In a particularly preferred aspect, the spring may be interchangeable to adjust the pressing force applied to the fibers.

According to one preferred aspect of the present invention, a width of a region in the base member where the sensor unit is mounted may be larger than a width of the sensor unit. This reduces the bending of the fibers at the corners of the sensor unit, which is useful for further improving the measurement accuracy.

According to one preferred aspect of the present invention, the device may be configured to be capable of wired or wireless connection to an external equipment for storing and/or processing the data outputted from the sensor unit. For the wireless connection to the external equipment, for example, Wi-Fi® or Bluetooth® can be used.

According to one preferred aspect of the present invention, at least a part of the sensor unit and/or the nipping member coming into contact with the fibers may be formed of a material that is not susceptible to generation of electrostatic forces when the device is being moved relative to the fibers. This helps to further improve the measurement accuracy.

Non-limiting and representative embodiments of the present invention will now be explained in detail below referring to the attached drawings.

An exemplary embodiment of the present invention will now be described with reference to <FIG>. Described below is a hand-portable device for measuring the frictional properties of human hair, more specifically for estimating the frictional coefficient thereof in a state of growing from the scalp, i.e. under "vivo" conditions such as those met in hair salons. However, the exemplary embodiment of the present invention can also be used to measure the frictional properties of hair in a cut and tensioned state, i.e. under "vitro" conditions such as those met in a laboratory. Furthermore, the exemplary embodiment of the present invention can also be used to measure the frictional properties of various natural or synthetic fibers other than hair.

<FIG> shows a device <NUM> for measuring frictional properties of fibers according to one embodiment of the present invention in a state in which the device <NUM> is connected to external equipment <NUM>, that is, a data logger <NUM> for storing the data outputted from a sensor unit <NUM> (described below in more detail) of the device <NUM> and a personal computer <NUM> for processing the data. In this embodiment, the device <NUM> is configured to be wired to the external device <NUM>. However, in other embodiments, the device <NUM> may be configured to be wirelessly connected to the external device <NUM> using, for example, Wi-Fi® or Bluetooth®.

As can be seen from <FIG>, the device <NUM> generally comprises: a base member <NUM> which functions as a handle for operation; the above mentioned sensor unit <NUM> mounted on a distal end (one end) <NUM> of the base member <NUM>; and a nipping member <NUM> connected to the base member <NUM> so that its distal end (one end) <NUM> faces the sensor unit <NUM>. In this embodiment, the distal end <NUM> is a solid plate shape. Further, from a proximal end of the base member <NUM> (not denoted by a reference numeral), a signal cable <NUM> connected to the external device <NUM> extends. Hair S (see <FIG>), more specifically a bundle of hair whose frictional properties are to be measured, is sandwiched between the sensor unit <NUM> and the distal end <NUM> of the nipping member <NUM>. In this device <NUM>, the base member <NUM> and the nipping member <NUM> are formed of a neutral material (for example, a suitable plastic) which is not susceptible to generation of electrostatic forces during measurement of the frictional properties of the hair S, i.e., when the device <NUM> is being moved relative to the hair S. Furthermore, a part of the sensor unit <NUM> coming into contact with the hair S is also formed of a neutral material (for example, a suitable rubber) which is not susceptible to generation of electrostatic forces when the device <NUM> is being moved relative to the hair S.

As can be seen from <FIG>, the base member <NUM> has a longitudinal axis X and a top surface <NUM>. Furthermore, as can be seen from <FIG> showing the device <NUM> viewed from the side, the sensor unit <NUM> is mounted on the side of the top surface <NUM> of the base member <NUM> so that a part thereof protrudes from the top surface <NUM>. More specifically, at the distal end <NUM> of the base member <NUM>, a shallow recess <NUM> is formed on the side of the top surface <NUM>. The upper portion of the sensor unit <NUM> protrudes beyond the top surface <NUM> from the bottom surface of the recess <NUM>. As the sensor unit <NUM>, for example, a biaxial sensor unit available from Trinity-Lab. of Tokyo, Japan can be used.

In addition to <FIG>, as can be further seen from <FIG>, the nipping member <NUM> cooperating with the sensor unit <NUM> is pin-connected to the base member <NUM> such that its distal end <NUM> faces an upper surface <NUM> of the sensor unit <NUM>. More specifically, a pair of brackets <NUM>, <NUM> are integrally formed on the top surface <NUM> of the base member <NUM>, and these brackets <NUM>, <NUM> have through holes 130a, 140a. On the other hand, the nipping member <NUM> generally has an inverted U-shaped profile in the intermediate section, and through holes 340a, 350a are formed in the opposing side walls <NUM>, <NUM> constituting this inverted U-shaped profile. In particular, as can be seen from <FIG>, a pin <NUM>, in the assembled state of the base member <NUM> and the nipping member <NUM>, extends through the holes 130a, 140a and the holes 340a, 350a and is held so as not to come off. As a result, the base member <NUM> and the nipping member <NUM> are pin-connected as described above.

Because the device <NUM> has such a configuration, the nipping member <NUM> is rotatable with respect to the base member <NUM> about pivot axis P above the top surface <NUM> of the base member <NUM> and perpendicular to the longitudinal axis X. In other words, the nipping member <NUM> is connected to the base member <NUM> such that the distal end <NUM> of the nipping member <NUM> is separated from the sensor unit <NUM> by pressing a proximal end (other end) <NUM> of the nipping member <NUM> which is present on the side opposite to the distal end <NUM> of the nipping member <NUM>, that is, in a manner like a seesaw. The nipping member <NUM> is rotatable until a stopper <NUM> (see <FIG>) projecting from the lower surface of the proximal end <NUM> of the nipping member <NUM> abuts against a stopper receiver <NUM> on the upper surface <NUM> of the base member <NUM>.

The state where the proximal end <NUM> of the nipping member <NUM> is not pressed, that is, the closed state of the nipping member <NUM>, is as shown in <FIG>. On the other hand, the state where the nipping member <NUM> is pivoted to the final position by pressing the proximal end <NUM> of the nipping member <NUM>, that is, the open state of the nipping member <NUM>, is as shown in <FIG>. The hair S whose frictional properties are to be measured, is loaded between the sensor unit <NUM> and the nipping member <NUM> in this open state. The sensor unit <NUM> measures a frictional force generated when, as shown in <FIG>, the device <NUM> is being relatively moved with respect to the hair S sandwiched between the sensor unit <NUM> and the nipping member <NUM> in a direction perpendicular to the longitudinal axis X of the base member <NUM>, i.e., in a lateral direction. The sensor unit <NUM> then outputs the value of the measured frictional force to the external device <NUM>, as described above.

In the device <NUM> configured as described above, during the measurement of the frictional properties, the nipping member <NUM> applies a constant pressing force on the hair S sandwiched between the sensor unit <NUM> and the nipping member <NUM>. More specifically, as can be seen from <FIG> showing the structure of the connecting portion of the base member <NUM> and the nipping member <NUM> in a disassembled state, in this device <NUM>, two substantially V-shaped springs <NUM>, <NUM> are interposed between the base member <NUM> and the nipping member <NUM>, in particular the proximal end <NUM> thereof. These springs <NUM>, <NUM> each include coil sections 410a, 420a at its bend and the pin <NUM> connecting the nipping member <NUM> to the base member <NUM> passes through these coil sections 410a, 420a. The springs <NUM>, <NUM> thus arranged always apply a force pushing up the proximal end <NUM> of the nipping member <NUM> thereto. Therefore, the springs <NUM>, <NUM> function to exert a constant pressing force on the hair S sandwiched between the sensor unit <NUM> and the nipping member <NUM>.

In this embodiment, the spring rate of the springs <NUM>, <NUM> is selected such that the nipping member <NUM> exerts a pressing force of about <NUM> N on the sandwiched hair S, although is not limited thereto. In addition, the springs <NUM>, <NUM> can be replaced to adjust the pressing force applied to the sandwiched hair S.

The nipping member <NUM> comprises first and second protrusions <NUM>, <NUM> on its face facing the sensor unit <NUM> at the distal end <NUM> of the nipping member <NUM>. Both of the first and second protrusions <NUM>, <NUM> have elongated flat plate shapes and are arranged parallel to each other. The first and second protrusions <NUM>, <NUM> serve as a guide for the hair (especially a bundle of hair) that ensures that the hair S is located within the measurement space between the sensor unit <NUM> and the nipping member <NUM>. In this embodiment, the height of the first protrusion <NUM> disposed on the tip side of the nipping member <NUM> is slightly lower than the height of the rear second protrusion <NUM>.

As can be seen from <FIG> showing the portion of the base member <NUM> where the sensor unit <NUM> is provided as viewed from above, the first and second protrusions <NUM>, <NUM> are arranged such that the sensor unit <NUM> is located between the first protrusion <NUM> and the second protrusion <NUM> when the nipping member <NUM> is closed to apply the pressing force on the hair S sandwiched between the sensor unit <NUM> and the nipping member <NUM>. That is, the first and second protrusions <NUM>, <NUM> are spaced apart by a slightly greater distance than the dimension D of the sensor unit <NUM> along the longitudinal axis X of the base member <NUM>.

As can also be seen from <FIG>, in this embodiment, a width B<NUM> of a region in the base member <NUM> where the sensor unit <NUM> is mounted is larger than a width B<NUM> of the sensor unit <NUM>. As a result, on both sides of the sensor unit <NUM>, support areas 160a, 160b for reducing the bending of the hair S at the corners of the sensor unit <NUM> is formed. More specifically, these support areas 160a, 160b are present on both sides of the shallow recess <NUM> of the base member <NUM> and are indicated by shading in <FIG>.

<FIG> shows the situation in which frictional properties of the hair S are being measured using the device <NUM> configured as described above. Prior to the measurement, the bundle of hair S whose frictional properties are to be measured, is sandwiched between the sensor unit <NUM> and the distal end <NUM> of the nipping member <NUM>. The amount of hair sandwiched between the sensor unit <NUM> and the nipping member <NUM> is adjustable, but in this embodiment, for example, it is about <NUM> to <NUM> grams, preferably <NUM> gram. In this nipped state, the nipping member <NUM> applies a constant pressing force on the hair S by the action of the spring <NUM>, <NUM>. Furthermore, the bundle of hair S is guided from both sides of the sensor unit <NUM> by the first and second protrusions <NUM>, <NUM>.

After the hair S is set on the device <NUM>, it is moved by an operator, that is, manually (or automatically if necessary) in the direction of the length of the hair S, that is, in a direction Y orthogonal to the longitudinal axis X of the base member <NUM>, at a constant speed. While the device <NUM> is moving in the direction Y, the sensor unit <NUM> measures the frictional force F generated during this movement together with a constant pressing force (vertical load) W applied to the hair S by the nipping member <NUM>. It should be noted here that the pressing force W acts perpendicular to the upper surface <NUM> of the sensor unit <NUM>, while the frictional force F occurs in a direction opposite to the direction of movement Y of the device <NUM> (see <FIG>). Subsequently, the sensor unit <NUM> outputs the measured values of the constant pressing force W and the measured frictional force F to the external equipment <NUM>. In this embodiment, the frictional coefficient (the dynamic frictional coefficient) µ of the hair S is calculated by the following equation in the external equipment <NUM>: <MAT> The value of the frictional coefficient of the hair S thus obtained is subsequently stored and/or processed by the external device <NUM>. However, in an alternative embodiment, the frictional coefficient µ of the fiber to be measured may be directly output from the device <NUM> to the external device <NUM>.

Measurement of the frictional properties of hair, more specifically, a swatch of hair, was carried out under vitro conditions by different operators, that is, operator-<NUM> and operator-<NUM>, using the device described above. Three kinds of hair, that is, "natural", "slightly bleached", and "medium bleached" are objects to be measured. Measurement was performed a plurality of times, and an average value of the frictional coefficient and a standard deviation (SD) were calculated. The results are shown in <FIG>. As can be seen from <FIG>, almost irrespective of the hair quality, the standard deviation (SD) of the measured values by both operator-<NUM> and operator-<NUM> is very small. From this, it is understood that measurement using the device according to the embodiment of the present invention realizes high reproducibility.

Measurement of the frictional properties of hair was carried out on successive different dates, that is, Day-<NUM> and Day-<NUM>, using the device described above. Three kinds of hair, that is, "natural", "slightly bleached", and "medium bleached", are objects to be measured. Measurement was performed a plurality of times, and an average value of the frictional coefficient and a standard deviation (SD) were calculated. The results are shown in <FIG> together with p-value (Significant Probability). As can be seen from <FIG>, almost irrespective of the hair quality, the standard deviation SD of the measured values on both Day-<NUM> and Day-<NUM> is very small. From this, it is understood that measurement using the device according to the embodiment of the present invention realizes high repeatability.

Measurement of the frictional properties of hair was carried out using the device described above. The different model's hair, that is, "model-<NUM>", "model-<NUM>", and "model-<NUM>" are objects to be measured. Measurement was performed a plurality of times, and an average value of the frictional coefficient and a standard deviation (SD) were calculated. The results are shown in <FIG>. As can be seen from <FIG>, almost irrespective of the hair quality, the standard deviation SD of the measured values is very small. From this, it is understood that measurement using the device according to the embodiment of the present invention realizes high accuracy under the vivo conditions.

Measurement of the frictional properties of hair, more particularly a swatch of hair, was carried out under vitro conditions using the device described above. The objects to be measured are: once-washed and conditioner-applied natural hair (1sh + conditioner), once-washed natural hair (1sh), three-times-washed natural hair (3sh), five-times-washed natural hair (5sh), and <NUM>-times-washed natural hair (10wh). Measurement was performed a plurality of times, and an average value of the frictional coefficient and a standard deviation (SD) were calculated. The results are shown in <FIG>. As can be seen from <FIG>, almost irrespective of the type and frequency of treatments applied to the hair, the standard deviation SD of the measured values is very small. From this, it is understood that measurement using the device according to the embodiments of the present invention also realizes high accuracy under vitro conditions.

Measurement of the frictional properties of the fibers was carried out using the device described above. Three kinds of fibers, that is, "paper", "cotton cloth", and "vinyl sheet", are objects to be measured. Measurement was performed a plurality of times, and an average value of the frictional coefficient and a standard deviation (SD) were calculated. The results are shown in <FIG>. As can be seen from <FIG>, almost irrespective of the fiber quality, the standard deviation SD of the measured values is very small. From this, it is understood that measurement using the device according to the embodiment of the present invention realizes high accuracy on not only hair but also other fibers.

Claim 1:
A device (<NUM>) for measuring frictional properties of fibers (S), the device (<NUM>) comprising:
a base member (<NUM>) having a longitudinal axis (X) and a top surface (<NUM>);
a sensor unit (<NUM>) mounted on a side of the top surface (<NUM>) of the base member (<NUM>) at one end (<NUM>) of the base member (<NUM>); and
a nipping member (<NUM>) pivotably connected to the base member (<NUM>) about a pivot axis (P) above the top surface (<NUM>) of the base member (<NUM>) such that one end (<NUM>) of the nipping member (<NUM>) faces the sensor unit (<NUM>);
wherein
fibers (S) whose frictional properties are to be measured are sandwiched between the sensor unit (<NUM>) and the one end (<NUM>) of the nipping member (<NUM>);
the sensor unit (<NUM>) is configured such that it measures at least a frictional force generated when the device (<NUM>) is being relatively moved with respect to the fibers (S) sandwiched between the sensor unit (<NUM>) and the nipping member (<NUM>) in a direction crossing the longitudinal axis (X) of the base member (<NUM>), and outputs the measurement data; and
the nipping member (<NUM>) applies a constant pressing force on the fibers (S) sandwiched between the sensor unit (<NUM>) and the nipping member (<NUM>) during the measurement of the frictional force,
the device being characterized in that:
the nipping member (<NUM>) comprises first and second protrusions (<NUM>, <NUM>) on its face facing the sensor unit (<NUM>) at the one end (<NUM>) of the nipping member (<NUM>), and wherein the first and second protrusions (<NUM>, <NUM>) are arranged such that the sensor unit (<NUM>) is located between the first protrusion (<NUM>) and the second protrusion (<NUM>) when the nipping member (<NUM>) is closed to apply the pressing force on the fibers (S) sandwiched between the sensor unit (<NUM>) and the nipping member (<NUM>).