HAIR CUTTING DEVICE AND HAIR CUTTING SYSTEM

A hair cutting device according to the present disclosure comprises an optical waveguide. The optical waveguide comprises a light irradiator for irradiating hair protruding from a skin with light to cut the hair. At least at a time of cutting the hair, a power density of light passing through the optical waveguide is more than or equal to 50 kW/cm2. This makes it easy to efficiently cut hair with light with which the light irradiator irradiates the hair. That is, it is possible to apply sufficient light energy for cutting the hair from the optical waveguide to the hair, and it is possible to cut the hair in a relatively short time. Therefore, for example, a width increases such as a thickness or hardness of hair that can be cut.

TECHNICAL FIELD

The present disclosure relates generally to a hair cutting device and a hair cutting system, and more particularly to a hair cutting device and a hair cutting system that cut hair by causing light to act on the hair.

BACKGROUND ART

PTL 1 describes a device configured to cut hair using laser light. The device described in PTL 1 includes a laser light source and a fiber optical system. The laser light source is configured to generate laser light having a wavelength selected to target a predetermined chromophore for effectively cutting hair. The fiber optical system has a proximal end, a distal end, an outer wall, and a cutting region disposed toward the distal end and extending along a part of a sidewall. The fiber optical system receives laser light from the laser light source at the proximal end and guides the laser light from the proximal end toward the distal end, and, when the cutting region comes into contact with the hair, emits light from the cutting region toward the hair.

CITATION LIST

Patent Literature

SUMMARY OF THE INVENTION

However, the configuration described in PTL 1 requires improvement in practical use of the hair cutting device using light.

The present disclosure has been made in view of the above circumstances, and an object of the present disclosure is to provide an improved hair cutting device and hair cutting system.

A hair cutting device according to one aspect of the present disclosure comprises an optical waveguide. The optical waveguide comprises a light irradiator. The light irradiator irradiates hair protruding from a skin with light to cut the hair. At least at a time of cutting the hair, a power density of light passing through the optical waveguide is more than or equal to 50 kW/cm2.

A hair cutting system according to an aspect of the present disclosure comprises the hair cutting device and a light source for generating light to be input to the optical waveguide.

According to the present disclosure, there is an advantage of providing an improved hair cutting device and hair cutting system.

DESCRIPTION OF EMBODIMENT

First Exemplary Embodiment

An outline of hair cutting device1and hair cutting system10according to the present exemplary embodiment will be described below with reference toFIGS.1A to2B. Hair cutting device1is a device that cuts hair91by causing light to act on hair91. Hair91to be cut by hair cutting device1is, for example, “facial hair” of a human, but is not limited to “facial hair” and includes various hairs protruding from skin92of a human and the like. InFIGS.1B,2A, and2B, hair91and skin92are indicated by imaginary lines (two-dot chain lines).

In short, unlike general “razors” or “scissors” that cut hair91with a physical “blade”, hair cutting device1and hair cutting system10cut hair91by applying hair91light energy instead of the “blade”. Therefore, hair cutting device1and hair cutting system10are less likely to damage skin92and the like around hair91, and are less likely to be physically deteriorated such as nicks and chips, as compared with general “razors” or “scissors”.

As illustrated inFIGS.1A and1B, hair cutting system10according to the present exemplary embodiment includes grip2and head3. Grip2includes light source21(seeFIG.1B) that generates light. Head3includes optical waveguide4and holding member5. Optical waveguide4includes light receiver43(seeFIG.1B) in grip2, and the light generated by light source21is input to light receiver43of optical waveguide4, whereby the light is transmitted in optical waveguide4. In the present exemplary embodiment, as an example, light source21is a laser light source, and light transmitted in optical waveguide4is laser light.

Here, optical waveguide4includes light irradiator40. Optical waveguide4cuts hair91by irradiating hair91with light from light irradiator40. Holding member5holds optical waveguide4in head3. Hair cutting device1cuts hair91by irradiating hair91to be cut with light from light irradiator40of optical waveguide4. Specifically, by bringing light irradiator40having a refractive index close to a refractive index of hair91to be cut into contact with hair91, hair cutting device1causes light leakage from light irradiator40to hair91, and cuts hair91with energy of the light.

In the present exemplary embodiment, a part of hair cutting system10corresponding to head3constitutes hair cutting device1. In other words, hair cutting device1according to the present exemplary embodiment includes optical waveguide4and holding member5. Head3corresponding to hair cutting device1constitutes hair cutting system10together with grip2including light source21. In other words, hair cutting system10according to the present exemplary embodiment includes hair cutting device1and light source21. Light source21generates light to be input to optical waveguide4.

In the present exemplary embodiment, hair cutting device1includes optical waveguide4, and optical waveguide4includes light irradiator40. Light irradiator40irradiates hair91protruding from skin92with light to cut hair91. Here, the refractive index of light irradiator40is smaller than the refractive index of surface921(seeFIG.2A) of skin92.

According to this configuration, since the refractive index of light irradiator40is smaller than the refractive index of surface921of skin92, options such as the material of optical waveguide4including light irradiator40increase, and hair cutting device1becomes easily achieved. Furthermore, according to this hair cutting device1, for example, when skin92is appropriately irradiated with light from light irradiator40, an action on skin92such as sterilization or activation can also be expected. As a result, there is an advantage of providing improved hair cutting device1.

In the present exemplary embodiment, hair cutting device1includes optical waveguide4, and optical waveguide4includes light irradiator40. Light irradiator40irradiates hair91protruding from skin92with light to cut hair91. Here, at least at the time of cutting hair91, the power density of the light passing through optical waveguide4is more than or equal to 50 kW/cm2.

According to this configuration, since the power density of the light passing through optical waveguide4at the time of cutting hair91is more than or equal to 50 kW/cm2, it is easy to efficiently cut hair91with the light with which light irradiator40irradiates hair91. That is, it is possible to apply sufficient light energy for cutting hair91from optical waveguide4to hair91, and it is possible to cut hair91in a relatively short time. Therefore, for example, there is an advantage of increasing a width such as a thickness or hardness of hair91that can be cut, and, as a result, of providing improved hair cutting device1.

In the present exemplary embodiment, hair cutting device1includes optical waveguide4and holding member5that holds optical waveguide4. Optical waveguide4includes light irradiator40. Light irradiator40irradiates hair91protruding from skin92with light to cut hair91. Holding member5holds optical waveguide4in such an aspect that light irradiator40is exposed from at least one face.

According to this configuration, since holding member5holds optical waveguide4in such an aspect that light irradiator40is exposed from at least one face of holding member5, even if hair91or skin92comes into contact with light irradiator40, for example, positional deviation or the like of optical waveguide4hardly occurs. That is, for example, at the time of cutting hair91, even if an external force from hair91or skin92acts on light irradiator40, optical waveguide4is less likely to be detached or damaged by the external force. As a result, there is an advantage of providing improved hair cutting device1.

Details of hair cutting device1and hair cutting system10according to the present exemplary embodiment will be described below with reference toFIGS.1A to6.

Hereinafter, as an example, three axes of an X axis, a Y axis, and a Z axis orthogonal to one another are set, and in particular, an axis along the length of light irradiator40is referred to as the “X axis” and an axis along the traveling direction of light irradiator40is referred to as the “Y axis”. The X axis, the Y axis, and the Z axis are all virtual axes, and the arrows indicating “X”, “Y”, and “Z” in the drawings are merely described for the sake of description, and are not accompanied by entities. These directions are not intended to limit directions of hair cutting device1and hair cutting system10when used.

The “hair” referred to in the present disclosure includes various hairs91protruding from skin92, i.e., various hairs extending from skin92, and includes, for example, various body hairs such as human hairs, facial hairs, eyebrows, leg hairs, nose hairs, or ear hairs. Furthermore, for example, various hairs91protruding from skin92of mammals such as dogs or cats and other animals are also included in the “hair” referred to in the present disclosure. That is, hair cutting device1according to the present exemplary embodiment is a device for cutting these hairs91. The “skin” referred to in the present disclosure also includes artificial skins and the like. In the present exemplary embodiment, as an example, a case where hair91to be cut by hair cutting device1is hair protruding from human skin92, particularly “facial hair” of an adult male will be described. That is, hair91to be cut by hair cutting device1is hair that has grown from human facial skin92. Human skin92including facial skin92is also referred to as “skin”.

The “cutting” of hair91referred to the present disclosure includes cutting hair91in general, and includes, for example, cutting hair91at the root (i.e., shaving hair), trimming hair91at an appropriate length, and cutting only the tip of hair. Therefore, the “hair cutting device” referred to in the present disclosure includes, for example, a “shaver” or a “hair shaving device”, which is a device for shaving hair91, and a “trimmer”, a “hair clipper”, or a “scissors”, which is a device for cutting the hair at an appropriate length. Furthermore, the “cutting” of hair91referred to in the present disclosure includes not only cutting hair91into two at a substantially planar cut surface, but also damaging a cut portion of hair91and breaking hair91at a cut part. In the present exemplary embodiment, as an example, a case where hair cutting device1and hair cutting system10are “shavers” suitable for cutting (i.e., shaving) hair91(facial hair) to be cut at the root will be described.

The “laser light” referred to in the present disclosure means light amplification by stimulated emission of radiation. Examples of light source21that generates laser light include a semiconductor laser (laser diode (LD)) using recombination light emission of a semiconductor. The laser light has characteristics of higher coherence, higher output (power density), higher monochromaticity (single wavelength), and higher directivity than those of light generated by a light emitting diode (LED).

The “optical waveguide” referred to in the present disclosure means an optical member that guides light along a desired path by passing the light. Specific examples of the optical waveguide include an optical fiber having a core and a cladding having refractive indices different from each other and having the core covered with the cladding. The optical fiber can guide light along a desired path by passing light into the core using total reflection of light at an interface between the core and the cladding. Here, the optical waveguide is not particularly limited to a transmission path through which a communication signal (optical signal) passes, and generally means an optical member that guides light along the desired path.

The “holding” referred to in the present disclosure means that one of two objects supports the other object such that the two objects continue to maintain a positional relationship with each other. Here, the relative positional relationship between the two objects may slightly change, and one object and the other object may not be firmly fixed together. That is, holding member5may hold optical waveguide4in an aspect where the positional relationship between optical waveguide4and holding member5slightly changes.

The “refractive index” referred to in the present disclosure is a value obtained by dividing a light velocity in vacuum by a light velocity in a medium (more precisely, a phase velocity). The refractive index is basically determined depending on substance, and for example, the refractive index of air is “1.0003” and the refractive index of water is “1.3334”. Even for the same substance, the refractive index may vary depending on the wavelength of incident light, but in the present disclosure, the refractive index is indicated for light having a wavelength of 404.7 nm (h line of mercury) unless otherwise specified.

The “power density” referred to in the present disclosure means light intensity per unit area (1 cm2). The unit of the power density is “kW/cm2” or “J/(s·cm2)”. Even when the distribution of the light intensity varies in a cross section of optical waveguide4, an average power density averaged over the entire cross section of core41is obtained by dividing the light intensity passing through optical waveguide4by the sectional area of core41of optical waveguide4. In the present disclosure, unless otherwise specified, the average power density thus obtained is referred to as “power density”.

(2.2) Overall Configuration

First, an overall configuration of hair cutting system10according to the present exemplary embodiment will be described with reference toFIGS.1A and1B.

As described above, hair cutting system10includes hair cutting device1and light source21. Hair cutting device1includes optical waveguide4and holding member5that holds optical waveguide4. Optical waveguide4includes light irradiator40, and outputs light from light irradiator40when light generated by light source21is input. Hair cutting system10cuts hair91by inputting light generated by light source21to optical waveguide4of hair cutting device1, and irradiating hair91from light irradiator40of optical waveguide4with the light.

More specifically, as the refractive index of light irradiator40, hair cutting system10adopts a value close to the refractive index of hair91to be cut. As a result, in a state where hair91is in contact with light irradiator40, light leaks from light irradiator40to hair91, and hair91is cut by energy of the light. On the other hand, in a state where hair91is not in contact with light irradiator40and only air (refractive index: 1.0) is in contact with light irradiator40, the amount of light leakage from light irradiator40can be suppressed to be small by the difference in refractive index between light irradiator40and the air.

In the present exemplary embodiment, as described above, hair cutting system10includes grip2including light source21and head3constituting hair cutting device1. As illustrated inFIGS.1A and1B, grip2includes first case20, and first case20accommodates light source21and the like. As an example, first case20is formed in a prismatic shape having a length along the Y axis. As illustrated inFIGS.1A and1B, head3includes second case30, and second case30accommodates optical waveguide4and the like. As an example, second case30is formed in a prismatic shape having a length along the X axis. In the present exemplary embodiment, one end in the longitudinal direction of first case20and a center in the longitudinal direction of second case30are coupled with each other, whereby first case20and second case30constitute a substantially T-shaped case as a whole when viewed from one side of the Z axis.

Thus, hair cutting system10having a substantially T-shaped appearance as a whole is used in the same manner as a “T-shaped razor”. That is, the user grips grip2of hair cutting system10, i.e., first case20with one hand to hold hair cutting system10when cutting (shaving) hair91(here, “facial hair”) to be cut. In this state, the user brings head3of hair cutting system10, i.e., one face of second case30in the Z axis direction into contact with skin92(of the face) of the user, and moves head3in the Y axis direction along skin92, thereby cutting hair91with light irradiator40of head3. At this time, as illustrated inFIG.1B, the user brings the face of second case30facing the negative orientation of the Z axis into contact with skin92and moves head3in the negative orientation of the Y axis, thereby cutting hair91positioned forward (i.e., in the negative orientation of the Y axis) in the traveling direction of head3.

In the present exemplary embodiment, as an example, both first case20and second case30are made of synthetic resin. First case20and second case30are coupled by an appropriate means such as adhesion, welding, bonding, or coupling using a fastening member (screw or the like).

In addition to first case20and light source21, grip2further includes control circuit6, optical system22, battery23, fan24, heat sink25, and operation unit26.

Control circuit6, optical system22, battery23, fan24, and heat sink25are all accommodated in first case20. Operation unit26is provided on one face (face facing the negative orientation of the Z axis) of first case20. Optical waveguide4included in head3is accommodated across first case20and second case30such that one end (light receiver43) of optical waveguide4is positioned in first case20of grip2.

Light source21converts electrical energy into optical energy to generate light to be input to optical waveguide4. In the present exemplary embodiment, light source21is a laser light source. That is, the light generated by light source21is laser light generated by stimulated emission. Here, light source21includes a semiconductor laser using recombination light emission of a semiconductor.

The wavelength of light generated by light source21is more than or equal to 400 nm. That is, light source21generates laser light having a peak wavelength or a dominant wavelength on the longer wavelength side than 400 nm. In the present exemplary embodiment, the wavelength of light generated by light source21is less than or equal to 700 nm. Although described in detail in the section of “(3) Action”, light having a wavelength in the range from 400 nm to 450 nm inclusive, for example, can be expected to have a sterilizing action on propionibacterium acnes and the like existing on skin92. Light having a wavelength in the range from 450 nm to 700 nm inclusive can be expected to have an activating action of skin92.

Control circuit6is a circuit that controls at least light source21. Control circuit6supplies power to light source21to cause light source21to emit light (turn on). Furthermore, control circuit6performs switching of on or off of light source21, adjustment of output (brightness, wavelength, or the like) of light source21, and the like. Control circuit6includes a printed wiring board (substrate) and a plurality of electronic components mounted on the printed wiring board. Control circuit6not only controls light source21but also fan24, operation unit26, and the like. Control circuit6will be described in detail in the section of “(2.6) Control circuit”.

Optical system22is disposed between light source21and optical waveguide4, and guides light from light source21to optical waveguide4. Optical system22includes a plurality of lenses. In the example ofFIG.1B, optical system22includes first lens221, second lens222, third lens223, and fourth lens224. However,FIG.1Bdoes not strictly illustrate the shape and arrangement of individual lenses, and merely schematically illustrates optical system22.

Battery23functions as a power supply that supplies power for driving control circuit6, light source21, fan24, and the like. In the present exemplary embodiment, as an example, battery23is a secondary battery such as a lithium ion battery (LIB) that can be charged and discharged.

Fan24is a cooling fan for cooling light source21. Specifically, fan24promotes heat dissipation of heat sink25by generating an airflow passing through heat sink25in first case20.

Heat sink25is made of a material having a relatively high thermal conductivity, for example, aluminum. Heat sink25is thermally coupled to light source21and mainly radiates heat from light source21.

Operation unit26receives a user's operation and outputs an electric signal responsive to the user's operation to control circuit6. In the present exemplary embodiment, as an example, operation unit26includes at least one mechanical switch such as a push switch or a slide switch.

Head3further includes fixing block32in addition to second case30, optical waveguide4, and holding member5.

Opening31for exposing at least light irradiator40to the outside of second case30is formed in second case30on a face that is in contact with user's skin92(i.e., a face facing the negative orientation of the Z axis). Opening31is formed in a rectangular shape having a length along the X axis. The inner space and the outer space of second case30are connected through opening31to each other.

Optical waveguide4, holding member5, and fixing block32are all accommodated in second case30. However, as described above, one end (light receiver43) of optical waveguide4is positioned in first case20of grip2. Therefore, the inner space of first case20and the inner space of second case30are continuous to each other, and optical waveguide4is accommodated across first case20and second case30. In the present exemplary embodiment, as an example, in addition to light irradiator40of optical waveguide4, holding member5and fixing block32are also exposed to the outside of second case30through opening31.

Optical waveguide4is an optical member that guides light from light source21along a desired path by passing light generated by light source21. In the present exemplary embodiment, as an example, optical waveguide4is an optical fiber. Optical waveguide4includes core41and cladding42, and core41is covered with cladding42. Furthermore, in the present exemplary embodiment, as illustrated inFIG.1B, optical waveguide4further includes light receiver43and protective sheath44. Light receiver43is accommodated in first case20and is disposed so as to oppose optical system22, thereby taking into optical waveguide4the light from light source21. Specifically, optical waveguide4is optically coupled to light source21via optical system22at light receiver43provided at the end of core41such that the light from light source21propagates through optical waveguide4(core41). Protective sheath44is a resin covering member configured to cover cladding42. That is, the optical fiber used as optical waveguide4in the present exemplary embodiment has a triple structure of core41, cladding42positioned outside core41, and protective sheath44positioned outside cladding42.

Optical waveguide4is routed in first case20and second case30such that at least light receiver43is disposed in first case20and a region extending from light receiver43is routed in second case30. Optical waveguide4has protective sheath44only in a portion from one end on light receiver43to a first intermediate part, and protective sheath44is removed and cladding42is exposed in a portion beyond the first intermediate part. Furthermore, optical waveguide4has cladding42only in a portion from the first intermediate part to a second intermediate part, and cladding42is removed and core41is exposed in a portion beyond the second intermediate part. In this manner, the region of optical waveguide4from which cladding42is removed and core41is exposed constitutes light irradiator40.

That is, in the present exemplary embodiment, optical waveguide4includes core41, and light irradiator40consists of core41. In other words, in the present exemplary embodiment, a portion (light irradiator40) of optical waveguide4for cutting hair91by irradiating hair91with light is formed only of core41. Optical waveguide4will be described in detail in the section of “(2.3) Configuration of hair cutting device”.

Holding member5is a member that holds optical waveguide4. Holding member5holds at least light irradiator40of optical waveguide4. That is, holding member5holds at least a region (light irradiator40) of optical waveguide4where cladding42is removed and core41is exposed. In the present exemplary embodiment, as an example, only light irradiator40is held by holding member5in optical waveguide4, and a region other than light irradiator40in optical waveguide4is appropriately positionally fixed with a structure other than holding member5. Holding member5is fixed to fixing block32. Holding member5is fixed to fixing block32by an appropriate means such as adhesion, welding, bonding, or coupling using a fastening member (screw or the like). As a result, optical waveguide4(light irradiator40) is indirectly fixed to fixing block32via holding member5. Holding member5will be described in detail in the section of “(2.4) Holding structure of optical waveguide”.

Fixing block32is fixed to second case30. Fixing block32is made of synthetic resin and is formed in a prismatic shape having a length along the X axis. Fixing block32is fixed to second case30by an appropriate means such as adhesion, welding, bonding, or coupling using a fastening member (screw or the like). Holding member5is fixed to fixing block32as described above. Therefore, optical waveguide4(light irradiator40) is indirectly fixed to second case30via holding member5and fixing block32.

Here, in head3, all of light irradiator40of optical waveguide4, holding member5, and fixing block32are exposed to the outside of second case30through opening31. Specifically, as illustrated inFIGS.1A and1B, fixing block32is disposed along a length (X axis) of opening31in second case30. Holding member5is fixed to a face of fixing block32facing forward (negative orientation of the Y axis) in the traveling direction of hair cutting device1. Moreover, fixing block32and holding member5are disposed close to a rear side (i.e., positive side of the Y axis) in the travelling direction of hair cutting device1so as to secure a gap on a front side in the travelling direction of hair cutting device1(head3) in a shorter direction (Y axis direction) of opening31.

Fixing block32and holding member5are disposed such that a face facing the negative orientation of the Z axis is flush with a face of second case30facing the negative orientation of the Z axis. Although described in detail in the section of “(2.4) Holding structure of optical waveguide”, optical waveguide4(light irradiator40) is fixed to a face of holding member5facing forward (negative orientation of Y axis) in the traveling direction of hair cutting device1.

Although not illustrated inFIGS.1A and1B, hair cutting system10may further include components such as a charging circuit for battery23or a display for displaying an operation state of hair cutting system10.

(2.3) Configuration of Hair Cutting Device

Next, a more detailed configuration of hair cutting device1according to the present exemplary embodiment, i.e., head3of hair cutting system10will be described with reference toFIGS.2A and2B.FIG.2Ais a schematic sectional view illustrating the configuration around optical waveguide4and holding structure5in hair cutting device1(head3).FIG.2Bis an enlarged view of the main part ofFIG.2A.

In the present exemplary embodiment, a part of hair cutting system10corresponding to head3constitutes hair cutting device1. Therefore, second case30, optical waveguide4, holding member5, and fixing block32included in head3are all components of hair cutting device1. That is, hair cutting device1according to the present exemplary embodiment further includes second case30and fixing block32in addition to optical waveguide4and holding member5. However, second case30and fixing block32are not essential components for hair cutting device1, and at least one of second case30and fixing block32can be omitted as appropriate.

As described above, optical waveguide4in hair cutting device1includes light irradiator40that irradiates hair91with light to cut hair91. In the present exemplary embodiment, optical waveguide4is an optical fiber having core41and cladding42. Cladding42covers core41over the entire circumference of core41. Here, both core41and cladding42have relatively high light transmissivity. However, the refractive index is different between core41and cladding42, and the refractive index of core41is larger than the refractive index of cladding42. With this configuration, the light incident on core41from light receiver43passes only through core41as much as possible due to total reflection or refraction at the interface between core41and cladding42, and reaches the tip end of optical waveguide4(end on the opposite side of light receiver43).

In the present exemplary embodiment, as an example, in optical waveguide4, both core41and cladding42are made of synthetic quartz. For example, core41is made of synthetic quartz, and cladding42is made of synthetic quartz to which an impurity has been added having a refractive index different from that of core41. In the present exemplary embodiment, as an example, when the fiber incidence numerical aperture (NA) is “0.1”, the refractive index of core41is “1.4698”, and the refractive index of cladding42is “1.4309”. When the fiber incidence NA is “0.2”, the refractive index of core41is “1.4698”, and the refractive index of cladding42is “1.309”. The NA and the refractive index mentioned here are merely examples, and are not intended to define a difference between the refractive index of core41and the refractive index of cladding42.

In optical waveguide4(optical fiber) having the above-described configuration, a region from the tip end opposite to light receiver43to the second intermediate part where cladding42is removed and core41is exposed constitutes light irradiator40. That is, in optical waveguide4, it is core41of the region where cladding42is removed and core41is exposed that constitutes light irradiator40that irradiates hair91with light.

However, more strictly speaking, in core41exposed by removing cladding42, a region covered with holding member5cannot leak light to hair91, and thus does not function as light irradiator40that irradiates hair91with light. In other words, in the present exemplary embodiment, light irradiator40consists of core41, and in particular, a region of core41that is exposed without being covered with cladding42is light irradiator40.FIGS.2A and2Band the like illustrate cross sections at a region of optical waveguide4where core41is exposed, and an end surface of cladding42.

In hair cutting device1according to the present exemplary embodiment, as described above, the refractive index of light irradiator40in optical waveguide4is smaller than the refractive index of surface921(seeFIG.2A) of skin92. Here, human skin92(skin) includes epidermis, dermis, and subcutaneous tissue. Surface921of skin92mentioned here means the outermost epidermis of these plurality of elements constituting skin92or the surface of the epidermis.

That is, in the present exemplary embodiment, since light irradiator40is formed of core41of optical waveguide4(optical fiber) including core41and cladding42, the refractive index of core41is set to be smaller than the refractive index of surface921of skin92. As an example, the refractive index of surface921of human skin92is assumed to be “1.4770”. Then, if the refractive index of core41, which is light irradiator40, is “1.4698” as described above, the condition that the refractive index of light irradiator40is smaller than the refractive index of surface921of skin92is satisfied.

More specifically, in the present exemplary embodiment, the refractive index of light irradiator40is less than or equal to 1.47. In short, the refractive index of light irradiator40is set in a range of less than or equal to “1.4700” so that the refractive index of light irradiator40is smaller than the refractive index of surface921of skin92. Thus, even if there is a slight variation in the refractive index of surface921of skin92, the refractive index of light irradiator40is smaller than the refractive index of surface921of skin92. That is, even when the refractive index of surface921of skin92is slightly smaller than “1.4770”, the condition that the refractive index of light irradiator40is smaller than the refractive index of surface921of skin92can be satisfied.

Furthermore, the refractive index of surface921of skin92is smaller than the refractive index of hair91. That is, when the refractive indices of the three of surface921of skin92, hair91, which is to be cut and protrudes from skin92, and light irradiator40(core41) are compared, the refractive index of hair91is the largest, the refractive index of surface921of skin92is the second largest, and the refractive index of light irradiator40is the smallest. As an example, the refractive index of human hair91(here, “facial hair”) to be cut by hair cutting device1is assumed to be “1.5432”. Then, if the refractive index of surface921of human skin92is “1.4770”, the condition that the refractive index of surface921of skin92is smaller than the refractive index of hair91is satisfied.

In short, in the present exemplary embodiment, as in the relationship of “light irradiator<skin<hair”, the refractive index of surface921of skin92is larger than that of light irradiator40(core41), and the refractive index of hair91is further larger than that of surface921of skin92. That is, the refractive index of light irradiator40is smaller than the refractive index of hair91to be cut and smaller than the refractive index of surface921of skin92.

As described above, in hair cutting device1according to the present exemplary embodiment, since the refractive index of light irradiator40is smaller than the refractive index of hair91to be cut, in a state where hair91is in contact with light irradiator40, light leaks from light irradiator40to hair91. Therefore, hair91is cut by energy of light leaking from light irradiator40to hair91. The principle (mechanism) of cutting hair91will be described in detail in the section of “(2.5) Usage example”. On the other hand, in a state where hair91is not in contact with light irradiator40and only air (refractive index: 1.0) is in contact with light irradiator40, the amount of light leakage from light irradiator40can be suppressed to be small by the difference in refractive index between light irradiator40and the air.

Furthermore, as the relationship of the refractive index, it is more preferable that the difference between the refractive index of light irradiator40and the refractive index of hair91to be cut is as small as possible. That is, while the refractive indices of the three of surface921of skin92, hair91, and light irradiator40satisfy the above-described magnitude relationship, the differences are preferably as small as possible. As a result, the refractive index of light irradiator40becomes a value close to the refractive index of hair91to be cut, and in a state where hair91is in contact with light irradiator40, light easily leaks from light irradiator40to hair91.

In the present exemplary embodiment, as an example, the refractive index of light irradiator40(core41) is “1.4698”, the refractive index of surface921of skin92is “1.4770”, and the refractive index of hair91is “1.5432”, and it can be said that the refractive index of light irradiator40and the refractive index of surface921of skin92are almost the same. Here, “the refractive indices are almost the same” means that, in a case where there are two refractive indices different from each other, both have values close to each other to such an extent that the smaller refractive index is included within the range of ±5% of the larger refractive index. In this case, for example, when the incident angle of light (angle with the normal line of surface921of skin92) is 80 degrees (incident NA is about 0.17), the reflectance (s polarized light) at the interface between an object having a refractive index of −5% of the refractive index of hair91and an object having a refractive index of that of hair91is 13.2%, the reflectance (s polarized light) at the interface between light irradiator40and hair91is 12.5%, and the reflectance (s polarized light) at the interface between skin92and hair91is 11.3%. Thus, even if the refractive index changes by −5%, the reflectance changes only by 2%. That is, in the present exemplary embodiment, since the refractive index (1.4698) of light irradiator40and the refractive index of surface921of skin92are in the range of ±5% of the refractive index (1.5432) of hair91, they can be said to be almost the same.

As described in the section of “(2.1) Definition”, the refractive index varies depending on the wavelength even for the same substance, but the above-described relationship of the refractive index is unchanged at least in the range of the wavelength of the light output from light source21. That is, at least in the range of the wavelength of the light output from light source21(e.g., in the range from 400 nm to 700 nm, inclusive), the refractive index satisfies the relationship of “light irradiator<skin<hair”.

Furthermore, since the refractive index of cladding42is smaller than the refractive index of core41, which is light irradiator40, when the above-described condition is satisfied, the refractive index of cladding42is the smallest among the refractive indices of the four of core41, cladding42, surface921of skin92, and hair91. That is, the relationship among the refractive indices of the four is “cladding<core<skin<hair”.

In hair cutting device1according to the present exemplary embodiment, as described above, at least at the time of cutting hair91, the power density of the light passing through optical waveguide4is more than or equal to 50 kW/cm2. That is, in optical waveguide4including core41and cladding42, since light passes through the inside of core41, the light intensity per unit area (1 cm2) in the cross section of core41is more than or equal to 50 kW. Here, the power density of the light passing through optical waveguide4is not necessarily more than or equal to 50 kW/cm2at all times, and only needs to be more than or equal to 50 kW/cm2at least at the time of cutting hair91(at the time of cutting hair91).

In the present exemplary embodiment, as an example, the power density of the light passing through optical waveguide4at the time of cutting hair91is from 50 kW/cm2to 300 kW/cm2, inclusive. The power density of the light passing through optical waveguide4at the time of cutting hair91is preferably more than or equal to 70 kW/cm2, at which hair91can be cut, and more preferably more than or equal to 75 kW/cm2. Furthermore, the power density of the light passing through optical waveguide4at the time of cutting hair91is more preferably more than or equal to 100 kW/cm2to cut hair91quickly (e.g., in about 0.1 s). Furthermore, the power density of the light passing through optical waveguide4at the time of cutting hair91is preferably less than or equal to 200 kW/cm2in consideration of the light output of a laser applicable as a consumer product, the fiber diameter, and the like. In the present exemplary embodiment, as an example, it is assumed that the initial value of the power density of the light passing through optical waveguide4at the time of cutting hair91is 100 kW/cm2.

Although details will be described in the section of “(2.5) Usage example” and the section of “(3) Action”, with this power density, it is easy for hair cutting device1to efficiently cut hair91with the light with which light irradiator40irradiates hair91.

In the present exemplary embodiment, the power density of the light passing through optical waveguide4is variable. That is, hair cutting device1according to the present exemplary embodiment is configured such that the power density of the light passing through optical waveguide4is not fixed to the initial value, and the power density of the light passing through optical waveguide4is changeable. Here, in particular, the power density of the light passing through optical waveguide4at the time of cutting hair91is not fixed to the initial value (100 kW/cm2) but is changeable from the initial value. The power density of the light passing through optical waveguide4at the time of cutting hair91is preferably variable in a range of more than or equal to 50 kW/cm2. The power density of the light passing through optical waveguide4may change continuously, i.e., may change stepwise (discontinuously).

In the present exemplary embodiment, the power density of the light passing through optical waveguide4is adjusted by the output from light source21. That is, hair cutting device1according to the present exemplary embodiment constitutes hair cutting system10together with light source21, and the power density of the light passing through optical waveguide4is adjusted by adjusting the output from light source21. The “adjust” as mentioned here includes both an aspect in which the power density is set to a predetermined value and an aspect in which the power density is changed as described above. In short, when the power density of the light passing through optical waveguide4is fixed to the initial value, the magnitude of the output from light source21is determined such that the power density becomes the initial value (100 kW/cm2). On the other hand, when the power density of the light passing through optical waveguide4is changed from the initial value to a desired value, the magnitude of the output from light source21is determined such that the power density becomes a desired value after the change. The configuration for determining the magnitude of the output from light source21will be described in detail in the section of “(2.6) Control circuit”.

(2.4) Holding Structure of Optical Waveguide

Next, details of the holding structure of optical waveguide4in hair cutting device1according to the present exemplary embodiment will be described with reference toFIGS.2A and2B.

As described above, hair cutting device1includes holding member5that holds optical waveguide4. Here, as illustrated inFIGS.2A and2B, holding member5holds optical waveguide4in an aspect where light irradiator40is exposed from at least one face. That is, optical waveguide4is held by holding member5in an aspect where at least light irradiator40is exposed on a face of holding member5facing forward (negative orientation of the Y axis) in the traveling direction of hair cutting device1. More specifically, entire core41constituting light irradiator40is not exposed but at least a face of core41facing forward (negative orientation of the Y axis) in the traveling direction of hair cutting device1is exposed from holding member5. A region of core41exposed from holding member5in this manner functions as light irradiator40that irradiates hair91with light to cut hair91.

Since holding member5is fixed to fixing block32of head3as described above, optical waveguide4(light irradiator40) is indirectly fixed to second case30of head3via holding member5and fixing block32.

Here, all of light irradiator40of optical waveguide4, holding member5, and fixing block32are exposed to the outside of second case30(seeFIG.1B) of head3through opening31(seeFIG.1B). Moreover, in opening31, fixing block32and holding member5are disposed biasedly on the rear side (i.e., positive side of the Y axis) in the traveling direction of hair cutting device1(head3) in the shorter direction (Y axis direction) of opening31. Therefore, as viewed from holding member5, a gap is secured between hair cutting device1and the peripheral edge of opening31on the front side (i.e., negative side of the Y axis) in the traveling direction of hair cutting device1, and hair91to be cut can be taken into opening31through the gap. In other words, as illustrated inFIG.2A, hair91to be cut can be introduced between a face of holding member5on which optical waveguide4is held such that light irradiator40is exposed, i.e., the face facing forward (negative orientation of the Y axis) in the traveling direction of hair cutting device1, and the peripheral edge of opening31.

With the above-described configuration, as illustrated inFIG.2A, hair91to be cut is introduced into second case30from opening31to a position opposing light irradiator40held by holding member5. In this state, a part of light irradiator40exposed from at least holding member5holding optional waveguide4(face facing the negative orientation of the Y axis) faces hair91to be cut. Thus, in optical waveguide4, light irradiator40can be brought into contact with hair91to be cut.

In the present exemplary embodiment, holding member5includes base51and adhesive member52. Adhesive member52bonds optical waveguide4to base51. Base51and adhesive member52are both made of a synthetic resin having light transmissivity. In particular, base51is a resin molded product molded using a mold. On the other hand, adhesive member52is a cured product obtained by curing a paste resin that is an adhesive. That is, adhesive member52is a cured product of an adhesive for joining base51with optical waveguide4.

Therefore, in order to achieve optical waveguide4in a state of being held by holding member5, adhesive member52only needs to be cured by embedding a part of optical waveguide4into adhesive member52, for example, in a state where paste adhesive member52is applied to base51. As a result, holding member5can hold optical waveguide4in an aspect where light irradiator40is exposed from one face of holding member5by exposing a part of optical waveguide4from adhesive member52while bonding optical waveguide4to base51with adhesive member52.

Base51is formed in a prismatic shape having a length along the X axis. Base51is fixed to fixing block32on a face facing forward (negative orientation of the Y axis) in the traveling direction of hair cutting device1by an appropriate means such as adhesion, welding, bonding, or coupling using a fastening member (screw or the like). In the present exemplary embodiment, the refractive index of base51is more than or equal to the refractive index of core41(light irradiator40).

As illustrated inFIG.2B, base51has four faces of opposing face511, side face512, back face513, and rear face514. The cross section orthogonal to the length (X axis) of base51has a substantially rectangular shape with these four faces as four sides. Opposing face511is a face opposing surface921of skin92at the time of cutting hair91. Side face512is a face that intersects surface921of skin92at the time of cutting hair91, and is a face adjacent to opposing face511. Back face513is a face facing the opposite side of opposing face511, and is a face adjacent to side face512. Rear face514is a face facing the opposite side to side face512and, is a face adjacent to back face513. That is, a face of base51facing the negative orientation of the Z axis is opposing face511, and a face facing the negative orientation of the Y axis is side face512. Furthermore, a face of base51facing the positive orientation of the Z axis is back face513, and a face facing the positive orientation of the Y axis is rear face514.

In the present exemplary embodiment, optical waveguide4is held on side face512of these opposing face511, side face512, back face513, and rear face514. That is, in the present exemplary embodiment, holding member5has side face512that intersects surface921of skin92at the time of cutting hair91. Optical waveguide4is held by side face512of holding member5. In particular, side face512is a face facing forward (negative orientation of the Y axis) in the traveling direction of hair cutting device1(head3) of base51. Therefore, light irradiator40of optical waveguide4is fixed to the face of holding member5facing forward (negative orientation of the Y axis) in the traveling direction of hair cutting device1.

Adhesive member52bonds optical waveguide4to base51. In the present exemplary embodiment, adhesive member52is provided on side face512of base51so that optical waveguide4is held on side face512of base51, and adhesive member52joins base51with optical waveguide4. Here, adhesive member52is disposed over the entire length in the longitudinal direction (X axis direction) of base51. Therefore, optical waveguide4is bonded to base51by adhesive member52over the entire length in the longitudinal direction of base51.

Since adhesive member52is a cured product of a paste resin as an adhesive, it is difficult to completely control the shape of adhesive member52, but it is possible to control the shape of adhesive member52to some extent by, for example, the amount of adhesive member52provided on side face512of base51. In the present exemplary embodiment, as illustrated inFIG.2B, in the cross section orthogonal to the longitudinal direction (X axis direction) of base51, the shape of adhesive member52is controlled such that a part of core41of optical waveguide4is buried in adhesive member52and a part of core41is exposed from adhesive member52. More specifically, adhesive member52crawls up along the periphery of core41due to the “wettability” of core41to a height of substantially a half (i.e., radius) of core41in the traveling direction (Y axis direction) of hair cutting device1. As a result, a half periphery of the periphery of core41of optical waveguide4is covered with adhesive member52, and the remaining half periphery is exposed from holding member5(adhesive member52) to constitute light irradiator40.

In the present exemplary embodiment, the refractive index of adhesive member52is smaller than the refractive index of light irradiator40. That is, if the refractive index of light irradiator40(core41) is “1.4698”, the refractive index of adhesive member52is smaller than “1.4698”. This can appropriately restrict the amount of light leakage from core41to adhesive member52, and can suppress a decrease in the power density of the light caused due to light leakage from core41more than necessary. In the present exemplary embodiment, since the region of optical waveguide4from which cladding42is removed and core41is exposed constitutes light irradiator40, adhesive member52comes into direct contact with light irradiator40(core41). Therefore, as an example, the refractive index of adhesive member52is equal to the refractive index of cladding42or less than or equal to the refractive index of cladding42.

As described above, the arrangement of fixing block32and holding member5with respect to second case30is determined such that the face of each of fixing block32and holding member5facing the negative orientation of the Z axis is flush with the face of second case30facing the negative orientation of the Z axis. More specifically, the face of each of fixing block32and base51of holding member5facing the negative orientation of the Z axis is flush with the surface of second case30facing the negative orientation of the Z axis. The face of base51facing the negative orientation of the Z axis is opposing face511. Therefore, in hair cutting device1(head3), in a state where the surface of second case30facing the negative orientation of the Z axis is brought into contact with skin92, fixing block32and base51of holding member5are also brought into contact with skin92.

In the present exemplary embodiment, positioner53that positions optical waveguide4is formed on side face512of base51where optical waveguide4is held. Positioner53positions optical waveguide4at least in a plane orthogonal to the length of optical waveguide4, i.e., in a Y-Z plane orthogonal to the X axis. As described above, in the present exemplary embodiment, holding member5includes positioner53that positions optical waveguide4in a plane orthogonal to the length of optical waveguide4.

Here, as illustrated inFIG.2B, positioner53includes a groove formed on side face512of base51. That is, positioner53is a groove formed on one face (side face512) of holding member5. The groove as positioner53is formed over the entire length in the longitudinal direction (X axis direction) of base51. Optical waveguide4is held on side face512of base51such that at least a part of core41exposed by removing cladding42is accommodated in the groove as positioner53. That is, at least a part of optical waveguide4is accommodated in the groove (positioner53).

Here, in the present exemplary embodiment, as an example, the groove as positioner53is a groove having a V-shaped cross section that becomes deeper toward the center in the shorter direction (width direction). As described above, by being disposed in the groove (positioner53) having a shape that becomes deeper toward the center in the shorter direction (width direction), optical waveguide4is disposed substantially at the center in the shorter direction (width direction) of the groove as positioner53due to a self-alignment effect. In particular, in the configuration in which optical waveguide4is bonded to base51by adhesive member52as described in the present exemplary embodiment, there is a possibility that optical waveguide4is displaced before adhesive member52is cured. Therefore, it is useful to exhibit the self-alignment effect.

In the present exemplary embodiment, holding member5holds optical waveguide4such that a gap is generated between light irradiator40and base51at least at a time other than the time of cutting hair91. That is, at least at a time other than the time of cutting hair91, as illustrated inFIG.2B, base51of holding member5and light irradiator40are not in contact with each other, and light irradiator40is held with a certain distance from base51. Here, in the present exemplary embodiment, as described above, the refractive index of base51is more than or equal to the refractive index of core41(light irradiator40). Therefore, if light irradiator40comes into contact with base51, light leaks to base51from the contact region of light irradiator40with base51, and the utilization efficiency of the light as hair cutting device1may be reduced. Therefore, in hair cutting device1according to the present exemplary embodiment, a decrease in light utilization efficiency is suppressed by separating light irradiator40from base51.

In particular, in the present exemplary embodiment, a region of adhesive member52interposed between base51and optical waveguide4has thickness D1more than or equal to the wavelength of the light passing through optical waveguide4. Thickness D1of the region of adhesive member52interposed between base51and optical waveguide4means the shortest distance between base51and optical waveguide4opposing each other across adhesive member52as illustrated inFIG.2B. That is, since adhesive member52for bonding optical waveguide4to base51is interposed between light irradiator40(core41) of optical waveguide4and base51, a gap is secured between light irradiator40and base51by this adhesive member52. However, when the thickness of adhesive member52interposed between base51and optical waveguide4is small (thin), light may leak to base51due to light (evanescent wave) seeping out to adhesive member52from the interface between optical waveguide4(core41) and adhesive member52. Such an evanescent wave is generated in a range of about one wavelength of light from the interface. Therefore, in the present exemplary embodiment, as illustrated inFIG.2B, thickness D1of adhesive member52interposed between base51and optical waveguide4is set to be more than or equal to the wavelength of the light passing through optical waveguide4, so that the evanescent wave is less likely to affect base51. As an example, when the wavelength of the light passing through optical waveguide4, i.e., the wavelength of the light generated by light source21is 700 nm, thickness D1of adhesive member52interposed between base51and optical waveguide4is more than or equal to 700 nm.

Furthermore, in the present exemplary embodiment, hair cutting device1has a contact surface that comes into contact with skin92at the time of cutting hair91. Optical waveguide4is held by holding member5such that height L0of light irradiator40from the contact surface is less than or equal to 100 μm. The “contact surface” referred to in the present disclosure means a face of hair cutting device1that comes into contact with skin92at the time of cutting hair91, and is basically a face positioned in the most negative direction of the Z axis in hair cutting device1. Here, hair cutting device1according to the present exemplary embodiment includes at least opposing face511of base51as a contact surface that comes into contact with skin92. Furthermore, since the face of fixing block32facing the negative orientation of the Z axis and the face of second case30facing the negative orientation of the Z axis are opposing faces511of base51, these are also included in the contact surface. Height L0of light irradiator40in the Z axis direction from the contact surface is equal to the height of light irradiator40from surface921of skin92at the time of cutting hair91. That is, in the present exemplary embodiment, as illustrated inFIG.2B, height L0of light irradiator40from opposing face511that is the contact surface is set to less than or equal to 100 μm, so that the distance (height) from surface921of skin92to light irradiator40at the time of cutting hair91becomes less than or equal to 100 μm.

However, in the present exemplary embodiment, height L0of light irradiator40from opposing face511, which is the contact surface, is more than or equal to 1 μm, and is not zero (0). In other words, in hair cutting device1, since light irradiator40has height L0from the contact surface (opposing face511) to some extent, light irradiator40can be separated from surface921of skin92at the time of cutting hair91. Thus, since light irradiator40of optical waveguide4is separated from surface921of skin92, for example, even if there is a bump such as an acne on surface921of skin92, light irradiator40is less likely to be caught by the bump.

When holding member5includes positioner53as in the present exemplary embodiment, the height of positioner53from the contact surface may be defined instead of height L0of light irradiator40from the contact surface. That is, the distance from the contact surface (opposing face511or the like) in the Z axis direction to the edge of the groove as positioner53is preferably less than or equal to 100 μm. In particular, in the present exemplary embodiment, the height of positioner53from the contact surface, i.e., the distance from the contact surface (opposing face511or the like) in the Z axis direction to the edge of the groove as positioner53is more than or equal to 1 μm.

(2.5) Usage Example

Next, a usage example of hair cutting device1and hair cutting system10according to the present exemplary embodiment will be described with reference toFIGS.3A to4B.

That is, in the present exemplary embodiment, hair cutting device1and hair cutting system10having the above-described configurations are used for cutting (here, “shaving”) hair91(here, “facial hair”). At this time, the user brings head3of hair cutting system10, i.e., the face of second case30facing the negative orientation of the Z axis into contact with skin92(of the face) of the user in a state where the user holds grip2of hair cutting system10with one hand to hold hair cutting system10. As a result, as illustrated inFIG.3A, hair91to be cut is introduced into second case30from opening31to a position opposing light irradiator40held by holding member5.

As illustrated inFIG.3A, in a state where light irradiator40is not in contact with hair91, air comes into contact with light irradiator40. Therefore, light leakage from light irradiator40hardly occurs due to a difference in refractive index between light irradiator40and air. In this state, the user moves head3(second case30) as hair cutting device1in the direction of arrow A1inFIG.3Aalong surface921of skin92.

As head3(second case30) moves, as illustrated inFIG.3B, light irradiator40comes into contact with hair91positioned forward (i.e., negative orientation of the Y axis) in the traveling direction of head3. At this time, hair91is irradiated with light from light irradiator40such that the light leaks to hair91due to a difference in refractive index between light irradiator40and hair91. That is, since the refractive index of light irradiator40is smaller than the refractive index of hair91to be cut, in a state where hair91is in contact with light irradiator40, light leaks from light irradiator40to hair91, and hair91is irradiated with light from light irradiator40.

Furthermore, in the state illustrated inFIG.3B, a part of the light with which light irradiator40irradiates hair91is scattered, so that skin92around hair91is also irradiated with the light from light irradiator40. Specifically, a part of the light which has leaked from the contact region with hair91in light irradiator40is scattered by hair91to irradiate skin92. As illustrated inFIG.3B, let the light with which mainly hair91is irradiated be first irradiation light Op1, and light with which mainly skin92is irradiated be second irradiation light Op2. That is, in a state where hair91is in contact with light irradiator40, light irradiator40irradiates hair91with first irradiation light Op1, and skin92is irradiated with second irradiation light Op2.

In particular, when hair91is irradiated with first irradiation light Op1from light irradiator40, hair91is cut by the energy of the light (first irradiation light Op1) with which light irradiator40irradiates hair91. In short, in the present exemplary embodiment, the wavelength (e.g., from 400 nm to 700 nm, inclusive) of the light output from light source21and passing through optical waveguide4includes the wavelength of the light absorbed by the chromophore (part of a molecule that provides the molecule with its color) in hair91. Therefore, first irradiation light Op1is converted into heat by being absorbed by the chromophore of hair91, and this heat breaks the bonds of the molecules of hair91, or melts or burns hair91. The chromophore that can be a target of the light (first irradiation light Op1) with which light irradiator40irradiates hair91includes, for example, a chromophore such as keratin or water.

As described above, the user can cut hair91protruding from skin92by moving head3(second case30) as hair cutting device1in the orientation of arrow A1(seeFIG.3A) along skin92. Therefore, after optical waveguide4passes, only the root of uncut hair91remains on skin92as illustrated inFIG.3C.

However, in hair cutting device1, as illustrated inFIG.3B, even if light irradiator40does not come into contact with hair91, hair91may be irradiated with light (evanescent wave) seeping out to the air side from the interface between light irradiator40and the air, for example. Therefore, not only when light irradiator40comes into contact with hair91, but also when light irradiator40and hair91come close to each other just before coming into contact, light irradiator40of hair cutting device1can sometimes cut hair91by irradiating hair91with first irradiation light Op1.

Depending on the condition of skin92, as illustrated inFIGS.4A and4B, when hair91(here, “facial hair”) is cut (here, “shaved”) using hair cutting device1and hair cutting system10, light irradiator40may come into contact with a part of skin92.FIGS.4A and4Billustrate use examples of hair cutting device1and hair cutting system10in a case where bump922such as an acne exists around hair91(around a hair root) on skin92. Bump922is a region of skin92that is raised compared to surface921of skin92around bump922.

That is, as illustrated inFIG.4A, in a state where light irradiator40is not in contact with hair91, air comes into contact with light irradiator40. Therefore, light leakage from light irradiator40hardly occurs due to a difference in refractive index between light irradiator40and air. In this state, the user moves head3(second case30) as hair cutting device1in the direction of arrow A1inFIG.4Aalong surface921of skin92.

As head3(second case30) moves, as illustrated inFIG.4B, light irradiator40comes into contact with hair91positioned forward (i.e., negative orientation of the Y axis) in the traveling direction of head3. At this time, hair91is irradiated with light (first irradiation light Op1) from light irradiator40such that the light leaks to hair91due to a difference in refractive index between light irradiator40and hair91. When hair91is irradiated with first irradiation light Op1from light irradiator40, hair91is cut by the energy of the light (first irradiation light Op1) with which light irradiator40irradiates hair91.

Furthermore, in the state illustrated inFIG.4B, light irradiator40also comes into contact with bump922around hair91on skin92. At this time, skin92is irradiated with light from light irradiator40such that the light leaks to skin92due to a difference in refractive index between light irradiator40and surface921(bump922) of skin92. That is, since the refractive index of light irradiator40is smaller than the refractive index of surface921of skin92, in a state where skin92is in contact with light irradiator40, light leaks from light irradiator40to skin92, and light irradiator40irradiates skin92with light (second irradiation light Op2). At this time, light irradiator40directly irradiates skin92with second irradiation light Op2, and bump922is mainly irradiated with second irradiation light Op2.

(2.6) Control Circuit

Next, the configuration of control circuit6of hair cutting system10according to the present exemplary embodiment will be described with reference toFIGS.5and6.

As illustrated inFIG.5, control circuit6is electrically connected to light source21, battery23, fan24, operation unit26, and the like. Control circuit6includes inputter61, mode switcher62, output adjuster63, and drive unit64.

Control circuit6includes, for example, a microcontroller having more than or equal to one processor and more than or equal to one memory. The microcontroller achieves a function as control circuit6by executing a program recorded in more than or equal to one memory with more than or equal to one processor. The program may be recorded in a memory in advance, may be provided by being recorded in a non-transitory recording medium such as a memory card, or may be provided through an electric communication line. In other words, the program is a program for causing more than or equal to one processor to function as control circuit6.

An electric signal responsive to a user's operation is input to inputter61from operation unit26. For example, when operation unit26receives an operation such as switching on or off of light source21, an electric signal responsive to this operation is input to inputter61.

Mode switcher62switches the operation mode of light source21. In the present exemplary embodiment, as the operation mode of light source21, there are two types of modes of a first mode and a second mode, both of which will be described later. Mode switcher62switches between the first mode and the second mode, for example, in accordance with the electrical signal from inputter61.

Drive unit64drives light source21by supplying power to light source21. That is, drive unit64supplies drive current I1to light source21including a semiconductor laser to cause light source21to emit light (turn on). Here, when driving light source21, as illustrated inFIG.5, drive unit64supplies rectangular wave-shaped drive current I1that alternately repeats light emission period T1and light-off period T2to light source21, thereby causing light source21to emit light. That is, drive unit64supplies drive current I1including the pulse current to light source21, and in response to this, light source21intermittently generates (blinks) light.

That is, since light source21emits light in light emission period T1of drive current I1and light source21is turned off in light-off period T2of drive current I1, light source21intermittently generates (blinks) light in accordance with the frequency of drive current I1. In short, light source21intermittently generates light by repeating light emission period T1and light-off period T2. In the present exemplary embodiment, as an example, the duty (ratio of light emission period T1to one cycle) of drive current I1is assumed to be 50%. That is, the time length of light emission period T1is equal to the time length of light-off period T2.

In the present exemplary embodiment, light source21has two types of operation modes of the first mode and the second mode.

The first mode is a mode in which the action on skin92is prioritized, and is a mode in which the time length of light emission period T1is less than or equal to 1/10000 seconds. That is, when the operation mode of light source21is the first mode, the time length of light emission period T1of light source21is less than or equal to 1/10000 seconds. In other words, in the first mode, drive unit64drives light source21with drive current I1having a frequency of more than or equal to 5 kHz. Thus, the maximum time for which light source21continuously generates light becomes less than or equal to 1/10000 seconds. In the present exemplary embodiment, as an example, the time length of light emission period T1of light source21when the operation mode of light source21is the first mode is 1/15000 seconds.

The second mode is a mode in which cutting of hair91is prioritized, and is a mode in which the time length of light emission period T1is more than or equal to 1/100 seconds. That is, when the operation mode of light source21is the second mode, the time length of light emission period T1of light source21is more than or equal to 1/100 seconds. In other words, in the second mode, drive unit64drives light source21with drive current I1having a frequency of less than or equal to 50 Hz. Thus, the minimum time for which light source21continuously generates light becomes more than or equal to 1/100 seconds. In the present exemplary embodiment, as an example, the time length of light emission period T1of light source21when the operation mode of light source21is the second mode is 1/80 seconds.

Here, control circuit6includes mode switcher62that switches between the first mode and the second mode. That is, in the present exemplary embodiment, the operation mode of light source21can be switched between the first mode in which the time length of light emission period T1is less than or equal to 1/10000 seconds and the second mode in which the time length of light emission period T1is more than or equal to 1/100 seconds.

Output adjuster63adjusts the output of light source21by controlling drive unit64. The output of light source21to be adjusted by output adjuster63includes the light intensity (brightness), the wavelength of light, and the like generated by light source21. Output adjuster63adjusts the output of light source21in accordance with an electric signal from inputter61, for example.

In particular, in the present exemplary embodiment, as described above, the power density of the light passing through optical waveguide4is adjusted by the output from light source21. Therefore, output adjuster63adjusts the power density of the light passing through optical waveguide4by adjusting the magnitude (power density) of the output of light source21. Specifically, output adjuster63adjusts the power density of the light output from light source21to optical waveguide4by changing the magnitude of drive current I1supplied from drive unit64to light source21.

Furthermore, as described above, in the case where the power density of the light passing through optical waveguide4is variable, a change in the power density is achieved by output adjuster63. That is, output adjuster63changes the power density of the light passing through optical waveguide4by changing the magnitude (power density) of the output of light source21. Output adjuster63changes the magnitude (power density) of the output of light source21in accordance with the electric signal from inputter61, for example.

Next, an operation example of hair cutting system10including control circuit6described above will be described with reference toFIG.6.FIG.6is a flowchart illustrating an operation example of hair cutting system10according to the present exemplary embodiment.

Hair cutting system10first determines whether or not the operation mode of light source21is the first mode (S1). At this time, if the operation mode is the first mode (S1: Yes), hair cutting system10sets the time length of light emission period T1to less than or equal to 1/10000 seconds and drives light source21with drive unit64(S2). On the other hand, if the operation mode is not the first mode (S1: No), hair cutting system10skips process S2and proceeds to process S3.

In process S3, hair cutting system10determines whether or not the operation mode of light source21is the second mode. At this time, if the operation mode is the second mode (S3: Yes), hair cutting system10sets the time length of light emission period T1to more than or equal to 1/100 seconds and drives light source21with drive unit64(S4). On the other hand, if the operation mode is not the second mode (S3: No), hair cutting system10skips process S4and ends the process.

Hair cutting system10repeatedly executes processes S1to S4. The flowchart illustrated inFIG.6is merely an example of the operation of hair cutting system10, and for example, the order of the processes may be appropriately changed, or the process may be appropriately added or omitted.

Next, expected actions of hair cutting device1and hair cutting system10according to the present exemplary embodiment will be described.

First, cutting of hair91, which is a basic function of hair cutting device1and hair cutting system10, is achieved by the mechanism described in the section of “(2.5) Usage example”.

Here, in the present exemplary embodiment, since first irradiation light Op1with which light irradiator40irradiates hair91has a wavelength of from 400 nm to 700 nm, inclusive, for example, first irradiation light Op1is easily absorbed by the chromophore included in hair91such as keratin and water. Furthermore, in the present exemplary embodiment, at least at the time of cutting hair91, the power density of the light passing through optical waveguide4is more than or equal to 50 kW/cm2. Therefore, first irradiation light Op1with which light irradiator40irradiates hair91can also have a power density (more than or equal to 50 kW/cm2) sufficient for cutting hair91.

In addition, in the present exemplary embodiment, as described above, when the operation mode of light source21is the second mode in which cutting of hair91is prioritized, the time length of light emission period T1of light source21becomes more than or equal to 1/100 seconds. Therefore, for example, in one light emission period T1, hair cutting device1can irradiate hair91with first irradiation light Op1having sufficient energy to cut hair91. Therefore, according to hair cutting device1and hair cutting system10of the present exemplary embodiment, hair91can be cut in a relatively short time. Therefore, according to hair cutting device1and hair cutting system10of the present exemplary embodiment, hair91is less likely to be entangled or caught, and smooth cutting of hair91is easily achieved.

Furthermore, since hair cutting device1and hair cutting system10can cut hair91in a relatively short time. Therefore, hair cutting device1is less likely to stay at one location, and the same location of skin92is less likely to be irradiated with light for a long time. Therefore, skin92is less likely to be damaged. As a result, there is an advantage of providing improved hair cutting device1and hair cutting system10.

Next, an action on skin92, which is a secondary function of hair cutting device1according to the present exemplary embodiment, will be described.

That is, since second irradiation light Op2with which light irradiator40irradiates skin92has a wavelength of from 400 nm to 700 nm, inclusive, an action on skin92such as sterilization or activation can also be expected. That is, when second irradiation light Op2with which skin92is irradiated has a wavelength in the range from 400 nm to 450 nm, inclusive, for example, it can be expected to have a sterilizing action on propionibacterium acnes and the like existing on skin92. In particular, as illustrated inFIGS.4A and4B, when bump922such as acne exists around hair91in skin92, light irradiator40directly irradiates bump922with second irradiation light Op2, and more effective sterilization action and the like can be expected.

Furthermore, in a case where second irradiation light Op2with which skin92is irradiated has a wavelength of, for example, from 450 nm to 700 nm, inclusive, an activation action of skin92can be expected. That is, when skin92is irradiated with second irradiation light Op2, skin92is activated, and an action such as so-called “skin beautifying effect”, which includes improvement of skin quality, can be expected.

Furthermore, in the present exemplary embodiment, at least at the time of cutting hair91, the power density of the light passing through optical waveguide4is more than or equal to 50 kW/cm2. Therefore, second irradiation light Op2with which light irradiator40irradiates skin92can also have the same power density (more than or equal to 50 kW/cm2) as that of the light passing through optical waveguide4. Here, in the present exemplary embodiment, height L0of light irradiator40from opposing face511, which is the contact surface, is more than or equal to 1 μm, and light irradiator40can be separated from surface921of skin92at the time of cutting hair91. Therefore, basically, skin92is irradiated with second irradiation light Op2scattered by hair91, and the power density of second irradiation light Op2with which skin92is irradiated can be appropriately suppressed to be small. On the other hand, since height L0of light irradiator40from opposing face511, which is the contact surface, is set to less than or equal to 100 μm, second irradiation light Op2can also be effectively caused to act on bump922such as acne.

In addition, in the present exemplary embodiment, as described above, when the operation mode of light source21is the first mode in which the action on skin92is prioritized, the time length of light emission period T1of light source21becomes less than or equal to 1/10000 seconds. Therefore, hair cutting device1can appropriately suppress the energy of second irradiation light Op2with which skin92is irradiated to be small in one light emission period T1, for example. Specifically, assuming that the power density of the light passing through optical waveguide4is 50 kW/cm2and that the time length of one light emission period T1is 1/10000 seconds, the energy of second irradiation light Op2per unit area is suppressed to 5 J/cm2at the maximum.

Therefore, according to hair cutting device1and hair cutting system10of the present exemplary embodiment, not only cutting of hair91but also a secondary function such as an action on skin92can be expected. Moreover, in hair cutting device1and hair cutting system10, by appropriately adjusting the energy of second irradiation light Op2with which skin92is irradiated, it is possible to expect an action such as sterilization or activation of skin92while making it difficult to damage skin92. As a result, there is an advantage of providing improved hair cutting device1and hair cutting system10.

The first exemplary embodiment is merely one of various exemplary embodiments of the present disclosure. The first exemplary embodiment can be variously changed in accordance with design and the like, as long as the object of the present disclosure can be achieved. The drawings referred to in the present disclosure are all schematic drawings, and the ratio of each of the size and the thickness of each component in the drawings does not necessarily reflect the actual dimensional ratio. Hereinafter, modifications of the first exemplary embodiment will be listed. The modifications described below can be applied in appropriate combination.

(4.1) First Modification

Hair cutting device1according to a first modification of the first exemplary embodiment will be described with reference toFIGS.7A to8D.

In the present modification, the configuration of optical waveguide4is different from that of hair cutting device1according to the first exemplary embodiment. That is, in the first exemplary embodiment, as illustrated inFIG.7A, in optical waveguide4including core41and cladding42, cladding42is removed for a predetermined length from the tip end side and core41is exposed, so that exposed core41constitutes light irradiator40. On the other hand, in the modification illustrated inFIG.7B, in optical waveguide4A, core41is exposed by removing only a part of cladding42in the circumferential direction of core41for a predetermined length from the tip end side. In the modification illustrated inFIG.7C, optical waveguide4B includes core41eccentric to cladding42, and only a part of core41in the circumferential direction is exposed from cladding42.

That is, in the modifications illustrated inFIGS.7B and7C, optical waveguides4A and4B each include cladding42that covers at least a part of core41. Light irradiator40is formed of a part of core41in the circumferential direction and includes a region exposed from cladding42. As described above, in the present modification, unlike the first exemplary embodiment in which cladding42does not exist over the entire circumference of core41in the circumferential direction, cladding42does not exist only in a part of core41in the circumferential direction. Therefore, in optical waveguides4A and4B in the present modification, a region of core41other than light irradiator40in the circumferential direction is covered with cladding42, and thus, leakage of light more than necessary from core41hardly occurs.

FIG.8Ais a schematic sectional view illustrating hair cutting device1in a case where optical waveguide4A illustrated inFIG.7Bis adopted instead of optical waveguide4on the basis of the configuration of hair cutting device1according to the first exemplary embodiment. Also in the modification illustrated inFIG.8A, similarly to hair cutting device1according to the first exemplary embodiment, holding member5holds optical waveguide4A in such an aspect where light irradiator40is exposed from at least one face. Even with such a configuration, light irradiator40of optical waveguide4A irradiates hair91with first irradiation light Op1and skin92is irradiated with second irradiation light Op2.

FIG.8Bis a schematic sectional view illustrating hair cutting device1in a case where optical waveguide4B illustrated inFIG.7Cis adopted instead of optical waveguide4on the basis of the configuration of hair cutting device1according to the first exemplary embodiment. Also in the modification illustrated inFIG.8B, similarly to hair cutting device1according to the first exemplary embodiment, holding member5holds optical waveguide4B in such an aspect where light irradiator40is exposed from at least one face. Even with such a configuration, light irradiator40of optical waveguide4B irradiates hair91with first irradiation light Op1and skin92is irradiated with second irradiation light Op2.

As illustrated inFIGS.8C and8D, a region that comes into contact with adhesive member52at least at one of base51and optical waveguides4A and4B preferably has uneven surfaces R1and R2including at least one of a plurality of recesses and a plurality of projections.FIG.8Cis a schematic view illustrating the holding structure with holding member5of optical waveguide4A inFIG.8A, andFIG.8Dis a schematic view illustrating the holding structure with holding member5of optical waveguide4B inFIG.8B. InFIGS.8C and8D, ranges (regions) in which uneven surfaces R1and R2are formed are shaded (dot-hatched). That is, the shades representing uneven surfaces R1and R2are merely provided for the sake of convenience only to represent the ranges of uneven surfaces R1and R2, and the shades are not applied to actual hair cutting device1.

In the example ofFIG.8C, the region of base51in contact with adhesive member52has uneven surface R2, and the region of optical waveguide4A in contact with adhesive member52has uneven surface R1. In the example ofFIG.8C, uneven surface R2is formed on an inner periphery of a groove formed on side face512of base51as positioner53, and uneven surface R1is formed on an outer periphery of cladding42of optical waveguide4A. More specifically, uneven surface R1is formed on the outer periphery of cladding42of optical waveguide4A, the outer periphery facing the opposite side (positive orientation of the Y axis) to light irradiator40.

Similarly, in the example ofFIG.8D, the region of base51in contact with adhesive member52has uneven surface R2, and the region of optical waveguide4B in contact with adhesive member52has uneven surface R1. In the example ofFIG.8D, uneven surface R2is formed on an inner periphery of a groove formed on side face512of base51as positioner53, and uneven surface R1is formed on an outer periphery of cladding42of optical waveguide4B. More specifically, uneven surface R1is formed on the outer periphery of cladding42of optical waveguide4A, the outer periphery facing the opposite side (positive orientation of the Y axis) to light irradiator40.

The “uneven surface” referred to in the present disclosure means a face including at least one of a plurality of recesses and a plurality of projections. That is, uneven surfaces R1and R2may include only a plurality of recesses or may include only a plurality of projections. Furthermore, uneven surfaces R1and R2may include a plurality of recesses and one project. In this case, as an example, uneven surfaces R1and R2include one shaded projection and a plurality of recesses including a shaded region surrounded by this protrusion. Similarly, as an example, uneven surfaces R1and R2may include one shaded recess and a plurality of projections including a shaded region surrounded by this recess.

Here, as an example, uneven surfaces R1and R2include a plurality of recesses and a plurality of projections. The plurality of recesses and the plurality of projections on uneven surfaces R1and R2have an significantly small size that cannot be individually identified with the naked eye, and each of uneven surfaces R1and R2includes a large number of recesses and a large number of projections. That is, the recess and the projection are finer than the entire uneven surfaces R1and R2. As a result, when a person sees uneven surfaces R1and R2, uneven surfaces R1and R2look like a rough “satin” due to the presence of the recess and the projection. Uneven surfaces R1and R2including a large number of fine recesses and projections are formed by embossing, for example.

Such uneven surfaces R1and R2are formed of a large number of recesses and projections, and have a pattern (irregularity shape) such as a satin, a wrinkle pattern (emboss), a wood grain, a rock grain, a sand grain, or a geometric pattern as a whole.

The size of such fine recesses and projections can be expressed by the surface roughness of uneven surfaces R1and R2, i.e., the shape of the recesses and projections is reflected on the roughness curve among the contour curves of uneven surfaces R1and R2. Therefore, the size of the recesses and projections on uneven surfaces R1and R2corresponds to calculated average roughness (Ra) of uneven surfaces R1and R2. Therefore, calculated average roughness (Ra) of the inner periphery (uneven surface R2) of the groove (positioner53) is larger than calculated average roughness (Ra) of a region other than the groove (positioner53) in side face512of base51. In other words, the region of base51that comes into contact with adhesive member52is a face that is rougher than the region of base51that does not come into contact with adhesive member52. Similarly, calculated average roughness (Ra) of the outer periphery (uneven surface R1) of cladding42is larger than calculated average roughness (Ra) of the outer periphery of core41. In other words, the regions of optical waveguides4A and4B that come into contact with adhesive member52are faces that are rougher than the regions of optical waveguides4A and4B that do not come into contact with adhesive member52.

Uneven surfaces R1of optical waveguides4A and4B may be achieved by a layer of an inorganic member or an organic member including at least one of a plurality of recesses and a plurality of projections formed on the outer periphery of cladding42. Alternatively, uneven surfaces R1of optical waveguides4A and4B may be achieved by a layer of an inorganic member or an organic member including at least one of a plurality of recesses and a plurality of projections formed on the outer periphery of core41.

Thus, since the region of at least one of base51and optical waveguides4A and4B that comes into contact with adhesive member52has uneven surfaces R1and R2, the adhesive power (adhesion) of adhesive member52between base51and optical waveguides4A and4B is improved by the anchor effect. As a result, it is easy to improve the durability of the holding structure of optical waveguides4A and4B with holding member5. Here, an example has been described in which the regions of both base51and optical waveguides4A and4B that come into contact with adhesive member52have uneven surfaces R1and R2, but the region of only one of base51and optical waveguides4A and4B that comes into contact with adhesive member52may have an uneven surface. Furthermore, even in an aspect other than the first modification (e.g., the first exemplary embodiment or a modification other than the first modification of the first exemplary embodiment), it is possible to adopt a configuration in which a region of at least one of base51and optical waveguide4that comes into contact with adhesive member52has an uneven surface.

As in hair cutting device1according to the first modification, when a part of light irradiator40(core41) is exposed from cladding42, adhesive member52only needs to bond cladding42with base51, and does not come into direct contact with light irradiator40(core41). Therefore, the refractive index of adhesive member52does not need to be equal to the refractive index of cladding42or equal to or less than the refractive index of cladding42, and can be appropriately set regardless of the refractive index of cladding42.

(4.2) Second Modification

Hair cutting device1according to a second modification of the first exemplary embodiment will be described with reference toFIGS.9A to9F. As illustrated inFIGS.9A to9F, the present modification is different from the first exemplary embodiment in the aspect of holding core41(light irradiator40) of optical waveguide4by holding member5.

In the examples illustrated inFIGS.9A to9C, the shape of the groove as positioner53formed on base51of holding member5is different from that of the first exemplary embodiment (V-shaped cross section). That is, in the example ofFIG.9A, the groove as positioner53is a groove having a semicircular arc (U-shaped) cross section that becomes deeper toward the center in the shorter direction (width direction). In the example ofFIG.9B, the groove as positioner53is a groove having a rectangular cross section with a uniform depth in the shorter direction (width direction). In the example ofFIG.9C, the groove as positioner53is a groove having a trapezoidal cross section that becomes deeper toward the center in the shorter direction (width direction).

In the examples illustrated inFIGS.9D to9F, holding member5holds optical waveguide4in a state where light irradiator40(core41) is in contact with base51. That is, in the example ofFIG.9D, core41is disposed in a groove having a V-shaped cross section as positioner53in a state where core41is in contact with the bottom face of positioner53(groove). In the example ofFIG.9E, positioner54is a rib protruding from both ends in the shorter direction on side face512(seeFIG.2B) of base51, and core41is disposed between a pair of ribs, which is positioner54. In the example ofFIG.9F, core41is disposed in a groove having a V-shaped cross section as positioner53so that core41fills positioner53(groove).

As clear from the example ofFIG.9F, inclusion of adhesive member52(seeFIG.2Aand the like) in holding member5is not an essential configuration of hair cutting device1. That is, even if holding member5does not have adhesive member52, holding member5can hold optical waveguide4, particularly core41as light irradiator40. That is, even when holding member5has only base51, light irradiator40of optical waveguide4can be held by holding member5(base51). In this case, light irradiator40(core41) only needs to be directly fixed to holding member5(base51). Examples of the means for directly fixing core41to base51include a means for integrally molding core41and base51by two-color molding or the like, a means for welding core41to base51, and a means for pressure-bonding core41to base51.

(4.3) Other Modifications

Hereinafter, modifications of the first exemplary embodiment other than the first modification and the second modification will be described.

A function similar to that of control circuit6of hair cutting system10according to the first exemplary embodiment may be embodied by a control method, a computer program, or a recording medium in which the computer program has been recorded. That is, the function corresponding to control circuit6may be embodied by a control method, a computer program, a recording medium in which the computer program has been recorded, or the like.

Hair cutting system10in the present disclosure includes a computer system in control circuit6and the like. The computer system mainly includes a processor and a memory as hardware. When a processor executes a program recorded in the memory of the computer system, a function as control circuit6in the present disclosure is implemented. The program may be recorded in advance in the memory of the computer system, may be provided through a telecommunication line, or may be provided by being recorded in a non-transitory recording medium readable by the computer system, such as a memory card, an optical disk, and a hard disk drive. The processor of the computer system includes one or a plurality of electronic circuits including a semiconductor integrated circuit (IC) or a large-scale integration (LSI). The integrated circuit such as the IC or LSI mentioned here is called differently depending on the degree of integration, and includes integrated circuits called a system LSI, a very large scale integration (VLSI), or an ultra large scale integration (ULSI).

Furthermore, a field-programmable gate array (FPGA) programmed after manufacturing of the LSI, or a logic device that can reconfigure a joining relationship inside the LSI or reconfigure a circuit section inside the LSI can also be adopted as the processor. The plurality of electronic circuits may be aggregated into one chip or may be provided dispersedly on a plurality of chips. The plurality of chips may be aggregated into one device or may be provided dispersedly on a plurality of devices. The computer system mentioned here includes a microcontroller having more than or equal to one processor and more than or equal to one memory. Therefore, the microcontroller also includes one or a plurality of electronic circuits including a semiconductor integrated circuit or a large-scale integrated circuit.

It is not an essential configuration for hair cutting system10that at least some functions of hair cutting system10are aggregated into one housing, and the components of hair cutting system10may be provided dispersedly in a plurality of housings. At least some of functions of control circuit6and the like in hair cutting system10may be achieved by, for example, a server or a cloud (cloud computing).

On the other hand, in the first exemplary embodiment, at least some functions of hair cutting system10dispersed in a plurality of housings (cases) may be aggregated into one housing (case). For example, hair cutting system10may include an inseparable integrated case instead of first case20and second case30. In this case, the components of hair cutting system10are accommodated into or attached to one case.

Operation unit26is not limited to a mechanical switch, and may be a touch switch, an optical or capacitance non-contact switch, a gesture sensor, or the like. Furthermore, operation unit26may be, for example, a communicator that receives an operation signal from an external terminal such as a smartphone, a voice inputter that receives a voice operation of the user, or the like.

Hair cutting device1may be combined with a shaver (including an electric shaver in which a blade is driven) that cuts hair91with a physical “blade”. In this case, hair cutting device1includes a physical “blade” in addition to light irradiator40, so that hair cutting device1can cut hair91with both the light irradiated from light irradiator40and the physical “blade”.

Optical waveguide4is not limited to an optical fiber in which core41and cladding42are made of synthetic quartz, and may be, for example, an optical fiber made of quartz (SiO2) or plastic. Examples of the plastic optical fiber include an optical fiber in which cladding42is made of a fluorine-based polymer or the like, and core41is made of a fully fluorinated polymer, polymethylmethacrylate, polycarbonate, or the like. Furthermore, optical waveguide4may be a slab waveguide, a rectangular optical waveguide, a photonic crystal fiber, or the like.

Optical waveguide4only needs to have core41as a minimum configuration, and cladding42may be appropriately omitted.

It is not an essential configuration to hair cutting device1that the refractive index of adhesive member52in holding member5is smaller than the refractive index of light irradiator40. That is, the refractive index of adhesive member52may be more than or equal to the refractive index of light irradiator40.

It is not an essential configuration to hair cutting device1that in holding member5, optical waveguide4is bonded to base51with adhesive member52over the entire length in the longitudinal direction (X axis direction) of base51. That is, holding member5may be configured to hold optical waveguide4by locally bonding optical waveguide4to base51with adhesive member52only in a part of base51in the longitudinal direction. In this case, optical waveguide4has a region bonded to base51and a region not bonded to base51. In this case, it is preferable that adhesive member52bonds optical waveguide4to base51at a plurality of places so as to suppress the deviation of optical waveguide4and the like as much as possible.

The gap between light irradiator40and base51only needs to be secured at least at a time other than the time of cutting hair91in hair cutting device1, and light irradiator40may come into contact with base51at the time of cutting hair91. For example, in the configuration in which optical waveguide4is bonded to base51with adhesive member52only at both ends in the longitudinal direction of base51, optical waveguide4is not bonded to base51at the center of base51in the longitudinal direction. In such a configuration, at the center of base51in the longitudinal direction, optical waveguide4only needs to be held in a state of floating from base51at a time other than at the time of cutting hair91with hair cutting device1. That is, at the center of base51in the longitudinal direction, optical waveguide4may be pressed against base51by receiving a reaction force from hair91at the time of cutting hair91with hair cutting device1, for example.

Light source21may generate not only light of a single wavelength but also light of a plurality of wavelengths, for example. In this case, light source21may simultaneously generate light of a plurality of wavelengths, or may sequentially generate the light while switching the frequency. In this configuration, since the light (first irradiation light Op1) with which light irradiator40irradiates hair91can target a plurality of chromophores corresponding to a plurality of wavelengths, it is possible to break bonds of a plurality of types of molecules and to improve cutting efficiency of hair91.

Hair cutting device1may include a plurality of optical waveguides4. In this case, hair cutting device1can cut hair91by irradiating hair91with light by light irradiator40of each of the plurality of optical waveguides4. Here, the plurality of optical waveguides4may pass light of the same wavelength or may pass light of a plurality of different wavelengths.

In the first exemplary embodiment, the operation mode of light source21is manually switched between the first mode and the second mode. However, the present invention is not limited to this example, and the operation mode may be automatically switched between the first mode and the second mode. As an example, when the operation mode of light source21includes a mixture mode as a third mode in addition to the first mode and the second mode, mode switcher62may be able to select the mixture mode (third mode). In the mixture mode (third mode), the first mode and the second mode are periodically and alternately switched, for example. Therefore, when the operation mode of light source21is the mixture mode (third mode), light source21alternately repeats the first mode in which the time length of light emission period T1is less than or equal to 1/10000 seconds and the second mode in which the time length of light emission period T1is more than or equal to 1/100 seconds.

Battery23is not limited to a secondary battery, and may be a primary battery. Furthermore, hair cutting system10is not limited to the battery-driven type, and may operate by receiving power supply from an external power supply such as a system power supply (commercial power supply), for example. In this case, battery23as hair cutting system10can be omitted.

The power density of the light passing through optical waveguide4may be adjusted by other than the output from light source21. For example, the power density of the light passing through optical waveguide4may be adjusted by optical system22or an optical filter included in optical waveguide4. Alternatively, the power density of the light passing through optical waveguide4may be adjusted by changing the radius of curvature of optical waveguide4. The power density of the light passing through optical waveguide4may be adjusted by exposing core41from a part of optical waveguide4and leaking a part of the light from core41.

A mirror may be disposed at an end (tip end) of optical waveguide4on the opposite side to light receiver43, and light reaching the tip end of optical waveguide4may be reflected by the mirror into optical waveguide4.

The function of acting on skin92is merely a secondary function of hair cutting device1, and can be omitted as appropriate. That is, hair cutting device1only needs to have a function of cutting hair91, which is a basic function.

Fixing block32is not limited to be made of synthetic resin, and may be made of metal, for example.

In a comparison between two values, “more than or equal to” includes both a case where the two values are equal and a case where one of the two values exceeds the other. However, the present invention is not limited to this definition, and “more than or equal to” mentioned here may be synonymous with “more than” including only a case where one of the two values exceeds the other. That is, whether or not to include the case where two values are equal to each other may be changed in any manner depending on settings of threshold values and the like. Accordingly, there is no technical difference between “more than or equal to” and “more than”. Similarly, “less than” may be synonymous with “less than or equal to”.

Second Exemplary Embodiment

As illustrated inFIGS.10A and10B, hair cutting device1A according to the present exemplary embodiment is different from hair cutting device1according to the first exemplary embodiment in the holding structure of optical waveguide4with holding member5. Hereinafter, the same configurations as those of the first exemplary embodiment are denoted by common reference numerals, and the description will be appropriately omitted. RegardingFIG.10Aand the subsequent drawings, in a sectional view of a region of optical waveguide4where core41is exposed, illustration of cladding42existing on the back side of the cross section (paper surface) is omitted.

In hair cutting device1A according to the present exemplary embodiment, as illustrated inFIG.10A, optical waveguide4(core41) is disposed biasedly on one end side (negative side of the Z axis) of base51in the Z axis direction. That is, in the present exemplary embodiment, the optical axis (central axis) of core41is disposed at a position of side face512of base51, the position being closer to the end edge on opposing face511(contact surface) as viewed from the center in the shorter direction (Z axis direction). As a result, as compared with the case where the optical axis of core41is positioned at the center of side face512of base51as in the first exemplary embodiment, optical waveguide4(core41) can be brought closer to surface921of skin92at the time of cutting hair91. Therefore, according to hair cutting device1A according to the present exemplary embodiment, hair91can be cut at a position closer to the root.

Here, as illustrated inFIG.10B, in the cross section orthogonal to the longitudinal direction (X axis direction) of base51, the shape of adhesive member52is controlled such that a part of core41of optical waveguide4is buried in adhesive member52and a part of core41is exposed from adhesive member52. More specifically, adhesive member52crawls up along the periphery of core41due to the “wettability” of core41to a height of substantially about ¾ (i.e., three times the radius) of core41in the traveling direction (Y axis direction) of hair cutting device1A. As a result, most of the periphery of core41of optical waveguide4is covered with adhesive member52, and the remaining part is exposed from holding member5(adhesive member52) to constitute light irradiator40. That is, adhesive member52covers a region other than light irradiator40in optical waveguide4.

In the present exemplary embodiment, as illustrated inFIG.10B, the face of adhesive member52facing the negative orientation of the Z axis is flush with opposing face511of base51. That is, adhesive member52formed so as to cover optical waveguide4(core41) by crawling up along the periphery of core41has a face that is flush with opposing face511, and this face functions as a contact surface that comes into contact with skin92at the time of cutting hair91. Since opposing face511is also flush with the face facing the negative orientation of the Z axis of fixing block32and second case30, the contact surface of adhesive member52is also flush with the surface facing the negative orientation of the Z axis of fixing block32and second case30.

Similarly to the first exemplary embodiment, optical waveguide4is held by holding member5such that height L1of light irradiator40from the contact surface (opposing face511or the like) becomes less than or equal to 100 μm. Furthermore, in the present exemplary embodiment, height L1of light irradiator40from opposing face511, which is the contact surface, is more than or equal to 1 μm, and is not zero (0). Here, also in the present exemplary embodiment, the height of positioner53from the contact surface may be defined instead of height L1of light irradiator40from the contact surface. In this case, the distance from the contact surface (opposing face511or the like) in the Z axis direction to the edge of the groove as positioner53is preferably less than or equal to 100 μm. In particular, in the present exemplary embodiment, the height of positioner53from the contact surface, i.e., the distance from the contact surface (opposing face511or the like) in the Z axis direction to the edge of the groove as positioner53is zero (0).

Also in hair cutting device1A according to the present exemplary embodiment described above, similarly to hair cutting device1according to the first exemplary embodiment, holding member5holds optical waveguide4in an aspect where light irradiator40is exposed from at least one face. Even with such a configuration, light irradiator40of optical waveguide4irradiates hair91with first irradiation light Op1(seeFIG.3B) and skin92is irradiated with second irradiation light Op2(seeFIG.3B).

Moreover, in the present exemplary embodiment, as compared with the first exemplary embodiment, optical waveguide4(core41) can be brought closer to surface921of skin92at the time of cutting hair91, and therefore the light from core41can be caused to more effectively act on skin92. That is, according to hair cutting device1A according to the present exemplary embodiment, when a part of the light with which light irradiator40irradiates hair91is scattered, skin92around hair91is easily irradiated with the scattered light as second irradiation light Op2.

Furthermore, in the present exemplary embodiment, the face of adhesive member52facing the negative orientation of the Z axis is flush with opposing face511and the like of base51, and functions as a contact surface that comes into contact with skin92at the time of cutting hair91. Therefore, at the time of cutting hair91, as illustrated inFIG.10A, adhesive member52comes into contact with surface921of skin92, and adhesive member52is held between core41of optical waveguide4and surface921of skin92. In other words, adhesive member52is interposed between core41of optical waveguide4and skin92.

Therefore, in hair cutting device1A, light is attenuated by adhesive member52as compared with a case where core41comes into direct contact with skin92, and the power density of the light with which core41irradiates skin92is easily adjusted appropriately. Specifically, the power density of the light with which core41irradiates skin92is adjusted by the difference in refractive index between core41and adhesive member52and the difference in refractive index between adhesive member52and surface921of skin92. In the present exemplary embodiment, since the refractive index of adhesive member52is smaller than the refractive index of core41(light irradiator40), the amount of light leakage from core41to adhesive member52can be suppressed to be relatively small. As a result, hair cutting system10using hair cutting device1A can sufficiently suppress damage to skin92even when the operation mode of light source21is the second mode in which cutting of hair91is prioritized, for example.

FIGS.11A and11Billustrate hair cutting device1A according to a modification of the second exemplary embodiment. Hair cutting device1A according to the modification is different from hair cutting device1A according to the second exemplary embodiment in that a height of light irradiator40from surface921of skin92is variable. Thus, just like a trimmer, hair cutting device1A can adjust the position of the cut surface of hair91when cutting hair91, i.e., the length of uncut hair91.

That is, in the example illustrated inFIG.11A, hair cutting device1A includes attachment33A detachably attached to second case30of head3, thereby increasing the height of light irradiator40from surface921of skin92. That is, when attachment33A is attached to the face of fixing block32and second case30facing the negative orientation of the Z axis, the height of light irradiator40from surface921of skin92increases by the thickness of attachment33A. Attachment33A includes a plurality of comb teeth331(only one comb tooth is illustrated inFIGS.11A and11B) protruding forward (negative orientation of the Y axis) in the traveling direction of hair cutting device1A. The plurality of comb teeth331are arranged side by side in the longitudinal direction (X axis direction) of light irradiator40. Hair cutting device1A can cut hair91by guiding hair91between a pair of adjacent comb teeth331among the plurality of comb teeth331.

In hair cutting device1A illustrated inFIG.11A, the contact surface that comes into contact with skin92at the time of cutting hair91is not opposing face511of base51or the like, but is a face of attachment33A facing the negative orientation of the Z axis. In this example, height L2of light irradiator40from the contact surface (face in attachment33A facing the negative orientation of the Z axis) becomes larger than height L1(seeFIG.10B) in the second exemplary embodiment.

In the example illustrated inFIG.11B, hair cutting device1A includes attachment33B detachably attached to second case30of head3, thereby increasing the height of light irradiator40from surface921of skin92. Attachment33B has a configuration common to attachment33A except that its thickness is larger than that of attachment33A. Therefore, in the example ofFIG.11B, height L3of light irradiator40from the contact surface (face of the attachment33B facing the negative orientation of the Z axis) is larger than height L2(seeFIG.11A).

In the examples illustrated inFIGS.11A and11B, attachments33A and33B are detachably attached to second case30, but the present invention is not limited to this configuration. For example, attachments33A and33B may change the height of light irradiator40from surface921of skin92by sliding with respect to second case30.

Various configurations (including modifications) described in the second exemplary embodiment can be adopted in appropriate combination with various configurations (including modifications) described in the first exemplary embodiment.

Third Exemplary Embodiment

As illustrated inFIGS.12A and12B, hair cutting device1B according to the present exemplary embodiment is different from hair cutting device1according to the first exemplary embodiment in the holding structure of optical waveguide4with holding member5. Hereinafter, the same configurations as those of the first exemplary embodiment are denoted by common reference numerals, and the description will be appropriately omitted.

In hair cutting device1B according to the present exemplary embodiment, as illustrated inFIGS.12A and12B, optical waveguide4is held on back face513of opposing face511, side face512, back face513, and rear face514of base51. That is, optical waveguide4is held not by side face512of base51as in the first exemplary embodiment but by back face513of base51. That is, in the present exemplary embodiment, holding member5has back face513facing an opposite side to opposing face511opposing surface921of skin92at the time of cutting hair91. Optical waveguide4is held by back face513of holding member5. In particular, on base51, back face513is a face along the traveling direction (Y axis direction) of hair cutting device1B, and is a face facing the positive orientation of the Z axis. Therefore, light irradiator40of optical waveguide4is fixed to the face (face facing the positive orientation of the Z axis) of holding member5along the traveling direction of hair cutting device1B.

In the present exemplary embodiment, positioner53that positions optical waveguide4is formed on back face513of base51where optical waveguide4is held. Positioner53includes a groove formed on back face513of base51. Optical waveguide4is held on back face513of base51with adhesive member52such that at least a part of core41exposed by removing cladding42is accommodated in the groove serving as positioner53.

Furthermore, in hair cutting device1B according to the present exemplary embodiment, optical waveguide4(core41) is disposed biasedly on one end side (negative side of the Y axis) of base51in the Y axis direction. That is, in the present exemplary embodiment, the optical axis (central axis) of core41is disposed at a position of back face513of base51, the position being closer to the end edge on the front (negative orientation of the Y axis) side in the traveling direction of hair cutting device1B as viewed from the center in the shorter direction (Y axis direction). As a result, in holding member5, while optical waveguide4is held on back face513of base51, light irradiator40easily comes into contact with hair91at the time of cutting hair91.

Also in the present exemplary embodiment, it is preferable that optical waveguide4is held by holding member5such that height L4of light irradiator40from the contact surface (opposing face511) in contact with skin92at the time of cutting hair91becomes less than or equal to 100 μm. However, since base51is interposed between core41and the contact surface (opposing face511), height L4of light irradiator40from opposing face511, which is the contact surface, is more than or equal to 1 μm, and is not zero (0).

Also in hair cutting device1B according to the present exemplary embodiment described above, similarly to hair cutting device1according to the first exemplary embodiment, holding member5holds optical waveguide4in an aspect where light irradiator40is exposed from at least one face. Even with such a configuration, light irradiator40of optical waveguide4irradiates hair91with first irradiation light Op1(seeFIG.3B) and skin92is irradiated with second irradiation light Op2(seeFIG.3B).

Moreover, in the present exemplary embodiment, base51is interposed between optical waveguide4(core41) and surface921of skin92. Therefore, skin92can be irradiated with the light leaking from core41to adhesive member52through base51. Here, light is attenuated by adhesive member52and base51, and the power density of the light with which core41irradiates skin92is easily adjusted appropriately. Specifically, the power density of the light with which core41irradiates skin92is adjusted by the difference in refractive index between core41and adhesive member52, the difference in refractive index between adhesive member52and base51, and the difference in refractive index between base51and surface921of skin92.

FIG.13illustrates hair cutting device1B according to a modification of the third exemplary embodiment. Hair cutting device1B according to the modification is different from hair cutting device1B according to the third exemplary embodiment in that base51is a sheet material. Here, as an example, it is assumed that the sheet material as base51is a flexible synthetic resin sheet.

In the present modification, the refractive index of the sheet material as base51is smaller than the refractive index of light irradiator40. That is, if the refractive index of light irradiator40(core41) is “1.4698”, the refractive index of the sheet material as base51is smaller than “1.4698”. Here, as an example, the refractive index of base51(sheet material) is substantially the same as the refractive index of cladding42.

Furthermore, in hair cutting device1B illustrated inFIG.13, since base51is a sheet material, a groove as positioner53(seeFIG.12B) is omitted, and optical waveguide4is bonded to one surface (one face in the thickness direction) of flat base51with adhesive member52. That is, in hair cutting device1B according to the present modification, base51is a sheet material, and optical waveguide4is held with adhesive member52on one face in the thickness direction of the sheet material.

According to the present modification, as compared with hair cutting device1B of the third exemplary embodiment, optical waveguide4(core41) can be brought closer to surface921of skin92at the time of cutting hair91. Therefore, according to hair cutting device1B of the present modification, hair91can be cut at a position closer to the root. The power density of the light with which core41irradiates skin92can be adjusted by the difference in refractive index between core41and adhesive member52, the difference in refractive index between adhesive member52and base51(sheet material), and the difference in refractive index between base51(sheet material) and surface921of skin92.

Various configurations (including modifications) described in the third exemplary embodiment can be adopted in appropriate combination with various configurations (including modifications) described in the first exemplary embodiment or the second exemplary embodiment.

Fourth Exemplary Embodiment

As illustrated inFIGS.14A and14B, hair cutting device1C according to the present exemplary embodiment is different from hair cutting device1according to the third exemplary embodiment in the shape of holding member5. Hereinafter, the same configurations as those of the third exemplary embodiment are denoted by common reference numerals, and the description will be appropriately omitted.

In the present exemplary embodiment, base51includes a plurality of protrusions55that protrude forward (negative orientation of the Y axis) in the traveling direction of hair cutting device1C. The plurality of protrusions55are arranged side by side in the longitudinal direction (X axis direction) of light irradiator40. In the present exemplary embodiment, as an example, base51and the plurality of protrusions55are a resin molded product integrally formed in an inseparable aspect. Here, faces of the plurality of protrusions55facing the negative orientation of the Z axis are flush with opposing face511(seeFIG.12B), which is a face of base51facing the negative orientation of the Z axis. Therefore, in hair cutting device1C, the contact surface that comes into contact with skin92at the time of cutting hair91is opposing face511of base51and the faces of the plurality of protrusions55facing the negative orientation of the Z axis.

Also in hair cutting device1C according to the present exemplary embodiment, similarly to the third exemplary embodiment, optical waveguide4is held on back face513(seeFIG.12B) of base51facing the positive orientation of the Z axis, which is a face along the traveling direction (Y axis direction) of hair cutting device1C. Therefore, optical waveguide4is held with adhesive member52near roots of the plurality of protrusions55on back face513of base51so as to expose light irradiator40. In other words, the plurality of protrusions55protrude from side face512(seeFIG.12B) of base51intersecting surface921of skin92at the time of cutting hair91. Light irradiator40held on base51is exposed from side face512of base51and between the pair of adjacent protrusions55.

In hair cutting device1C according to the present exemplary embodiment described above, at the time of cutting hair91, as illustrated inFIG.15, it is possible to cut hair91by guiding hair91between a pair of adjacent protrusions55among the plurality of protrusions55. That is, since light irradiator40of optical waveguide4held on base51is exposed between the pair of protrusions55, light irradiator40comes into contact with hair91guided between the pair of protrusions55, and light irradiator40irradiates hair91with first irradiation light Op1to cut hair91.

That is, in the present exemplary embodiment, holding member5has the plurality of protrusions55. The plurality of protrusions55protrude from one face (side face512) that intersects surface921of skin92at the time of cutting hair91and is a face (side face512) on which light irradiator40is exposed. Light irradiator40irradiates hair91introduced between the pair of adjacent protrusions55in the plurality of protrusions55with light. Therefore, light irradiator40does not come into contact with hair91over the entire length in the longitudinal direction, but can come into contact with hair91only with a part exposed from between the pair of adjacent protrusions55. As a result, in hair cutting device1C, the amount of light leaking from light irradiator40to hair91when light irradiator40comes into contact with hair91can be suppressed, and the loss of light passing through optical waveguide4can be suppressed to be small.

Also in hair cutting device1C according to the present exemplary embodiment, light irradiator40irradiates skin92with second irradiation light Op2(seeFIG.3B). However, a part of second irradiation light Op2is blocked by each of the plurality of protrusions55, and does not reach skin92. That is, since second irradiation light Op2from light irradiator40does not directly reach the part of skin92that becomes shadow of the plurality of protrusions55as viewed from light irradiator40, the energy of the light with which skin92is irradiated is easily adjusted to an appropriate level. In other words, since skin92is locally irradiated with second irradiation light Op2from the gap between the pair of adjacent protrusions55, the energy of the light with which skin92is irradiated can be suppressed to be small as compared with the case where a wide range of skin92is irradiated with the light.

Furthermore, as illustrated inFIGS.16A and16B, hair cutting device1C according to the present exemplary embodiment can partially press skin92with the plurality of protrusions55at the time of cutting hair91.FIGS.16A and16Bare schematic views illustrating the configuration around optical waveguide4and holding structure5when viewed from the front (negative orientation of the Y axis) in the traveling direction of hair cutting device1C at the time of cutting hair91.

That is, as illustrated inFIG.16A, when skin92on both sides of hair91to be cut is pressed by the pair of protrusions55, skin92around hair91exposed from between the pair of protrusions55is raised. Therefore, according to hair cutting device1C, hair91can be cut at a position closer to the root. Moreover, also regarding the action on skin92, as illustrated inFIG.16B, skin92raised between the pair of protrusions55approaches light irradiator40and easily comes into contact with light irradiator40, so that light irradiator40also efficiently irradiates skin92with light.

As a modification of the fourth exemplary embodiment, the shape of the plurality of protruding portions55can be changed as appropriate. For example, each of the plurality of protruding portions55is not limited to a linear shape in a plan view (as viewed from one side of the Z axis), and any shape such as a rectangular shape, a trapezoidal shape, a triangular shape, a semicircular shape, or a curved shape can be adopted.

Various configurations (including modifications) described in the fourth exemplary embodiment can be adopted in appropriate combination with various configurations (including modifications) described in the first exemplary embodiment, the second exemplary embodiment, or the third exemplary embodiment.

As described above, hair cutting device (1or1A to1C) according to the first aspect includes optical waveguide (4,4A, or4B). Optical waveguide (4,4A, or4B) includes light irradiator (40). Light irradiator (40) cuts hair (91) by irradiating hair (91) protruding from skin (92) with light. At least at the time of cutting hair (91), the power density of the light passing through optical waveguide (4,4A, or4B) is more than or equal to 50 kW/cm2.

According to this aspect, since the power density of the light passing through optical waveguide (4,4A, or4B) at the time of cutting hair (91) is more than or equal to 50 kW/cm2, it is easy to efficiently cut hair (91) with the light with which light irradiator (40) irradiates hair (91). That is, it is possible to apply sufficient light energy for cutting hair (91) from optical waveguide (4,4A, or4B) to hair (91), and it is possible to cut hair (91) in a relatively short time. Therefore, for example, there is an advantage of increasing a width such as a thickness or hardness of hair (91) that can be cut, and, as a result, of providing improved hair cutting device (1or1A to1C).

In hair cutting device (1or1A to1C) according to the second aspect, in the first aspect, the power density of the light passing through optical waveguide (4,4A, or4B) is variable.

According to this aspect, by changing the power density of the light passing through optical waveguide (4,4A, or4B), a desired action according to an application or a situation can be obtained.

Hair cutting system (10) according to the third aspect includes: hair cutting device (1or1A to1C) according to the first or second aspect; and light source (21) that generates light to be input to optical waveguide (4,4A, or4B).

According to this aspect, there is an advantage of providing improved hair cutting system (10).

In hair cutting system (10) according to the fourth aspect, in the third aspect, the power density of the light passing through optical waveguide (4,4A, or4B) is adjusted by the output from light source (21).

According to this aspect, the power density of the light passing through optical waveguide (4,4A, or4B) can be accurately adjusted by the output from light source (21).

In hair cutting system (10) according to the fifth aspect, in the third or fourth aspect, light source (21) intermittently generates light by repeating light emission period (T1) and light-off period (T2).

According to this aspect, consumption of electric energy in light source (21) can be suppressed.

In hair cutting system (10) according to the sixth aspect, in the fifth aspect, a time length of light emission period (T1) is less than or equal to 1/10000 seconds.

According to this aspect, it is possible to irradiate with light having energy suitable for an action on skin (92).

In hair cutting system (10) according to the seventh aspect, in the fifth aspect, a time length of light emission period (T1) is more than or equal to 1/100 seconds.

According to this aspect, it is possible to irradiate with light having energy suitable for cutting hair (91).

In hair cutting system (10) according to the eighth aspect, in the fifth aspect, an operation mode of light source (21) is switchable between a first mode and a second mode. In the first mode, the time length of light emission period (T1) is less than or equal to 1/10000 seconds. In the second mode, the time length of light emission period (T1) is more than or equal to 1/100 seconds.

According to this aspect, it is possible to switch between irradiation with light of energy suitable for an action on skin (92) and irradiation with light of energy suitable for cutting hair (91).

In hair cutting system (10) according to the ninth aspect, in any of the fifth to eighth aspects, a wavelength of light generated by light source (21) is more than or equal to 400 nm.

According to this aspect, it is possible to irradiate with light having a wavelength suitable for an action on skin (92).

In hair cutting system (10) according to the tenth aspect, in any of the fifth to ninth aspects, light source (21) is a laser light source.

According to this aspect, it is possible to irradiate with light having energy suitable for cutting hair (91).

The configuration according to the second aspect is not an essential configuration to hair cutting device (1or1A to1C), and can be omitted as appropriate.

The configuration according to the fourth to tenth aspects is not an essential configuration to hair cutting system (10), and can be omitted as appropriate.

The hair cutting device and the hair cutting system can be applied to cutting of various hairs of a human or an animal other than a human in various fields such as home use, beauty, medical care, or nursing care.

REFERENCE MARKS IN THE DRAWINGS

10: hair cutting system

21: light source

T1: light emission period