HUMAN TISSUE TREATMENT DEVICE WITH OPTICAL OUTPUT MEMBER UTILIZING TOTAL REFRACTION AT ITS CONTACT SURFACE FOR IMPROVED SKIN AND EYE SAFETY - Patent application

Abstract

The body tissue treatment device 1 includes a plate-shaped light output member 25 having a contact surface 27 through which collimated treatment light 21 can be transmitted to body tissue 41. An inner surface 29 of the light output member has a faceted optical structure 31. The shape of the optical structure, the refractive index value n1 of the material of the light output member, and the mean propagation direction PAV2 of the treatment light received by the optical structure are such that, in positions where the contact surface is not in contact with the body tissue, the treatment light is reflected from the light output member toward the optical structure by total internal reflection, and, in positions where the contact surface is in contact with the body tissue, the treatment light is transmitted to the body tissue. A plate-shaped light redirection member 53 with a faceted optical structure 61 can be arranged parallel to and adjacent to the light output member to redirect the treatment light emitted by the device's light source 5 in the mean propagation direction PAV2.

Description

[Technical Field]

[0001] The present invention relates to a human body tissue treatment device, which includes a housing, at least one light source disposed within the housing and configured to emit treatment light, a collimator constructed and arranged to collimate the treatment light emitted by the light source, thereby establishing collimated treatment light having a first mean propagation direction, and a plate-shaped light output member made of an optically transparent material and having a contact surface, through which the collimated treatment light can be transmitted to the human body tissue when the human body tissue is in contact with the contact surface.

[0002] The present invention further relates to a shaving unit of an electric shaver comprising a body tissue treatment device as described herein.

[0003] The invention further relates to an electric shaver comprising a shaving unit as described herein. [Background technology]

[0004] Devices for treating human tissue, such as those mentioned above in the "Technical Field" section, are generally known. Summary of the Invention [Problem to be solved by the invention]

[0005] This device can be used, for example, to treat human skin with light. This device can be used, for example, to treat acne vulgaris on human skin with blue light or a combination of blue and red light. Another example of treatment is hair removal or hair growth inhibition. By using collimated treatment light, the light intensity applied to human tissue is relatively high, resulting in effective treatment. Effective treatment is achieved, particularly when the first mean propagation direction of the collimated treatment light is transverse, particularly perpendicular, to the contact surface of the light output member. However, this poses a safety risk if the contact surface of the light output member is not covered or not completely covered by human tissue. In such cases, the collimated treatment light may reach the user's eyes, which may cause eye damage or may reach parts of the human body that should not be treated.

[0006] To avoid such safety risks, a solution is known that prevents treatment light from being emitted through portions of the contact surface of the light output member that are not covered by human tissue. In this known solution, multiple light sources are arranged along (part of) the peripheral edge of the plate-shaped light output member, and treatment light emitted by the light sources is optically coupled into the plate-shaped light output member through the peripheral edge and guided through the plate-shaped light output member by total internal reflection (TIR) ​​at the two main surfaces of the plate-shaped light output member. Only where the contact surface of the light output member is in contact with human tissue, is the treatment light coupled from the light output member to the human tissue through the contact surface. Where the contact surface is not in contact with human tissue, the treatment light is not irradiated. A disadvantage of this solution is that the incoupling of treatment light through the relatively narrow peripheral edge of the plate-shaped light output member limits the light intensity applied to the human tissue.

[0007] US 10,226,297 B2 discloses a medical instrument having first and second jaw members movable relative to one another, which cooperate to grasp tissue between the first and second jaw members. The first jaw member has a tissue-contacting surface and an optical element including a plurality of crystals made of an optically transparent material, such as sapphire, crystal glass, or fused silica. One side of each crystal forms a portion of the tissue-contacting surface of the first jaw member. The first jaw member also includes a plurality of light sources that generate light beams directed at individual crystals. Some light sources direct the light beams at the crystals at a first angle, so that when tissue is not in contact with the tissue-contacting surface of the crystal, the light beams are totally internally reflected and circulate within the crystal in a counterclockwise direction. Other light sources direct the light beams at a second angle different from the first angle, so that when tissue is not in contact with the tissue-contacting surface of the crystal, the light beams are totally internally reflected and circulate within the crystal in a clockwise direction. The light beams are transmitted to the tissue only through the crystals in contact with the tissue. Therefore, no light is emitted from the crystals that are not in contact with tissue, thereby preventing light-induced eye damage. A drawback of known medical devices is that crystals that are not in contact with tissue are heated by absorption of light that circulates within the crystal due to total internal reflection. The heated crystals may subsequently damage tissue that they come into contact with. [Means for solving the problem]

[0008] It is an object of the present invention to provide a body tissue treatment device of the type described above in the "Technical Field" section that does not suffer from the disadvantages of the prior art devices described above in the "Summary of the Invention" section. In particular, it is an object of the present invention to provide a body tissue treatment device of the type described above in the "Technical Field" section, in which the collimated treatment light is applied from the collimator to an inner main surface of the plate-shaped light output member opposite the contact surface, resulting in a relatively high intensity of treatment light applied to the body tissue, but without the safety risk of high-intensity treatment light being emitted from portions of the light output member's contact surface that are not in contact with the body tissue, and without the risk of the light output member being overheated due to absorption of the collimated treatment light.

[0009] In order to achieve the above object, the present invention provides a human body tissue treatment device, comprising: a housing; at least one light source disposed within the housing and configured to emit treatment light; a collimator constructed and arranged to collimate the treatment light emitted by the light source, thereby establishing collimated treatment light having a first mean propagation direction; and a plate-shaped light output member made of an optically transparent material and having a contact surface, through which the collimated treatment light can be transmitted to the human body tissue when the human body tissue is in contact with the contact surface; an inner surface of the plate-shaped light output member opposite to the contact surface comprises an optical structure having one or more pairs of first and second facets, the first and second facets being oriented at a first angle α1 and a second angle α2, respectively, with respect to the contact surface; the first facets are configured to receive collimated treatment light, and at a location where the collimated treatment light is incident on each respective first facet, the collimated treatment light has a second mean propagation direction; the first angle α1, the second mean propagation direction, and the refractive index value n1 of the optically transparent material of the plate-shaped light output member are such that (i) the first facet transmits the received treatment light into the plate-shaped light output member by refraction, (ii) the contact surface reflects the received treatment light by total internal reflection (TIR) ​​at a position not in contact with the human tissue, and iii) the contact surface transmits the received treatment light from the plate-shaped light output member into the human tissue by refraction at a position in contact with the human tissue; the second facet is configured to receive treatment light reflected by TIR at the contact surface; The second angle α2 and the refractive index value n1 are such that the second facet transmits the reflected treatment light to the outside of the plate-shaped light output member by refraction.

[0010] In the human tissue treatment device according to the present invention, the treatment light collimated by the collimator is received by a first facet of an optical structure provided on the inner main surface of the plate-shaped light output member, facing away from the contact surface of the plate-shaped light output member. The first facet is located on the inner main surface of the plate-shaped light output member and transmits the collimated treatment light into the plate-shaped light output member by refraction, i.e., without substantial loss of light intensity, allowing a relatively large amount of light to be received and transmitted into the plate-shaped light output member via the inner main surface of the plate-shaped light output member. When the contact surface of the plate-shaped light output member is in contact with human tissue, such as human skin, the treatment light is transmitted into the human tissue by refraction at the contact surface, i.e., without substantial loss of light intensity. When the contact surface is not in contact with human tissue, or when the contact surface is not in contact with human tissue at all, the treatment light is totally reflected at the contact surface, resulting in the treatment light not being emitted into the surroundings of the device through the contact surface and not posing a safety risk. The treatment light totally reflected at the contact surface is received by a second facet of the optical structure provided on the inner main surface of the plate-shaped light output member and emitted to the outside of the plate-shaped light output member by refraction at the second facet. Thus, absorption of the treatment light by the plate-shaped light output member and associated heating of the plate-shaped light output member are limited. Treatment light transmitted from the plate-shaped light output member through the second facet can be absorbed by other parts of the human tissue treatment device disposed within the housing, thereby limiting heating of the plate-shaped light output member.

[0011] In a preferred embodiment of the human tissue treatment device according to the present invention, the refractive index n1 of the optically transparent material of the plate-shaped light output member is in the range of 1.4 to 1.7. A refractive index n1 in the range of 1.4 to 1.7 allows a relatively large angle of incidence of the second mean propagation direction of the collimated treatment light on the contact surface of the plate-shaped light output member at the position where the collimated treatment light is received by the first facet of the optical structure of the plate-shaped light output member, so that the light source can be placed at a practical position within the housing. Suitable materials for the plate-shaped light output member that provide a refractive index n1 in the range of 1.4 to 1.7 are, for example, polymethyl methacrylate (PMMA), polycarbonate, glass, or quartz glass. Even higher values ​​of the above-mentioned angle of incidence can be achieved by using a material with a refractive index n1 > 1.7, such as sapphire.

[0012] In a preferred embodiment of the human tissue treatment device according to the present invention, the first mean propagation direction is different from the second mean propagation direction, and the treatment device comprises a light redirecting member disposed between the collimator and the plate-shaped light output member and configured to redirect the collimated treatment light from the first mean propagation direction to the second mean propagation direction. The use of the light redirecting member allows the first mean propagation direction of the treatment light collimated by the collimator to be different from the second mean propagation direction of the collimated treatment light at the location where the collimated treatment light is received by the first facet of the optical structure of the plate-shaped light output member. This allows the light source and the collimator to be positioned and oriented in a practical manner within the housing relative to the plate-shaped light output member. For example, the light source and the collimator can be centrally disposed below the plate-shaped light output member, oriented such that the mean emission direction of the light source and the first mean propagation direction of the treatment light collimated by the collimator are perpendicular to the contact surface of the plate-shaped light output member.

[0013] In a further embodiment of the device for treating human tissue according to the invention, the light redirecting member comprises a plate-shaped carrier made of an optically transparent material and arranged parallel to and adjacent to an inner surface of the plate-shaped light output member; a first main surface of the plate-shaped carrier facing away from the plate-shaped light output member is flat, extends parallel to the contact surface, and is configured to receive collimated treatment light having a first mean propagation direction and transmit the received collimated treatment light through the plate-shaped carrier; a second main surface of the plate-shaped carrier facing the plate-shaped light output member is oriented at a third angle α3 with respect to the first main surface, and comprises an optical structure having one or more third facets configured to receive the collimated treatment light transmitted by the first main surface; The third angle α3, the first mean propagation direction, and the refractive index value n2 of the optically transparent material of the plate-shaped carrier are such that the third facet transmits and redirects the received collimated treatment light from the plate-shaped carrier into the second mean propagation direction by refraction.

[0014] In this further embodiment, the plate-shaped carrier provides a practical and compact structure of the light redirecting member, which, together with the plate-shaped light output member arranged parallel to and adjacent to the plate-shaped carrier, provides a practical and compact overall structure of the human tissue treatment device. Since the collimated treatment light is received at the first main surface of the plate-shaped carrier and transmitted and redirected by refraction at the third facet of the optical structure provided on the second main surface of the plate-shaped carrier, the light redirecting member allows the high-intensity collimated treatment light beam to be transmitted and redirected from the first mean propagation direction to the second mean propagation direction without substantial loss of light intensity.

[0015] In yet another embodiment of the human tissue treatment device according to the present invention, the optical structure of the second main surface of the light redirecting member comprises one or more pairs of a fourth facet and a respective one of the one or more third facets, the fourth facet being oriented at a fourth angle α4 relative to the first main surface of the light redirecting member, the third angle α3 being equal to the second angle α2, and the fourth angle α4 being equal to the first angle α1. In this embodiment, the optical structure of the inner main surface of the plate-shaped light output member and the optical structure of the second main surface of the plate-shaped carrier may be identical, so that the plate-shaped light output member and the plate-shaped light redirecting member may actually be identical, and the plate-shaped light redirecting member is arranged in an inverted state relative to the plate-shaped light output member. This results in a simple and compact structure of the human tissue treatment device.

[0016] In a preferred embodiment of the human tissue treatment device according to the present invention, the collimator has first and second end faces and an elongated light guide extending in a direction perpendicular to the contact surface from the first end face to the second end face; the first end face is configured to receive treatment light emitted by the light source; the second end surface is configured to transmit the collimated treatment light toward the light redirection member; The light guide is configured to collimate treatment light received at the first end face by internal reflection of the received treatment light at a circumferential surface of the light guide.

[0017] This preferred embodiment is particularly suitable for devices with a single or limited number of light sources, which are arranged at a relatively large distance below the plate-shaped light output member and oriented so that the average light emission direction of the light source extends substantially perpendicular to the contact surface of the plate-shaped light output member. In such devices, the light guide provides a practical and structurally simple embodiment of a collimator, providing a relatively high degree of collimation of the light emitted by the light source. The light guide may have a bulky light guide body made of an optically transparent material and configured to collimate the treatment light received at the first end face by TIR of the treatment light received at the circumferential surface of the light guide body. Alternatively, the light guide may have a hollow light guide channel, which is configured to collimate the treatment light received at the first end face by reflection of the treatment light on the reflective inner surface of the light guide channel.

[0018] In a further embodiment of the human tissue treatment device according to the invention, the light guide has a central axis extending perpendicular to the contact surface and is circularly symmetrical about the central axis; The light guide has a cross-sectional area perpendicular to the central axis that gradually increases from the first end face to the second end face.

[0019] In this further embodiment, when the light source is arranged centrally on the central axis of the light guide and has an average light emission direction in the direction of the central axis, the light guide provides uniform collimation of the light emitted by the light source, viewed on a cross section of the light guide, and the degree of collimation of the emitted light is relatively high. In this further embodiment, the light guide can be embodied as a compound parabolic concentrator (CPC). Preferably, in this further embodiment, the first and second facets of the optical structure of the plate-shaped light output member are annular and extend concentrically with respect to the central axis of the light guide. If the light redirection member comprises a plate-shaped carrier with an optical structure according to the embodiments as previously described herein, the third facet and (if applicable) fourth facet of the optical structure of the light redirection member are also annular and extend concentrically with respect to the central axis.

[0020] A particular embodiment of the human tissue treatment device according to the present invention comprises a plurality of light sources configured to emit treatment light, and the collimator comprises a separate collimator element for each individual light source configured and arranged to collimate the treatment light emitted by the individual light source. In this embodiment, the light sources can be arranged at a relatively short distance below the plate-shaped light output member, and despite this short distance, can provide a uniform light intensity at the contact surface when regularly distributed over the entire area of ​​the plate-shaped light output member. This embodiment is preferred when only limited space is available below the plate-shaped light output member to accommodate the light sources and collimators. This embodiment can comprise a light redirection member as previously described herein, in which case each individual light source can have an average light emission direction perpendicular to the contact surface of the plate-shaped light output member, and a first average propagation direction of light collimated by the collimator element associated with each individual light source can also be perpendicular to the contact surface. The light redirection member can comprise a plate-shaped carrier comprising an optical structure according to an embodiment as previously described herein. In an alternative embodiment, the light redirecting member may comprise a separate light redirecting element for each individual light source disposed between the plate-shaped light output member and the collimator element associated with the individual light source, wherein each of said light redirecting elements may comprise a mirror or a prism.

[0021] Another embodiment of the human tissue treatment device according to the present invention comprises a plurality of light sources configured to emit treatment light, the collimator having a separate collimator element for each individual light source constructed and arranged to collimate the treatment light emitted by the individual light source; Each individual light source and each individual collimator element associated with an individual light source is oriented obliquely with respect to the contact surface of the plate-shaped light output member, so that the first mean propagation direction and the second mean propagation direction are parallel to each other.

[0022] In this embodiment, no light redirecting member or separate light redirecting element is required for each individual light source, since the first and second mean propagation directions are parallel to each other as a result of the oblique orientation of the light sources and collimator elements. The light sources can be positioned at a relatively short distance below the plate-shaped light output member, so that only limited space is required below the plate-shaped light output member to accommodate the light sources.

[0023] In a further embodiment of the human tissue treatment device according to the invention, the collimator has a plurality of optical fibers configured to guide the treatment light emitted by the light source to the plate-shaped light output member; the optical fiber has a fiber tip portion oriented such that the treatment light emitted by the fiber tip portion has a second mean propagation direction; The optical fiber is configured to receive treatment light emitted by the light source and maintain the received treatment light at a numerical aperture in the range of 0.01 to 0.2.

[0024] In this further embodiment, the use of an optical fiber allows the light source to be placed at any suitable or desired location within the housing, which provides increased flexibility in designing the overall layout of the human tissue treatment device. In this further embodiment, the fiber tip section is oriented such that the treatment light emitted by the fiber tip section has a second mean propagation direction, so no light redirection member is required. The numerical aperture value of the treatment light received and maintained by the optical fiber, ranging from 0.01 to 0.2, ensures that the treatment light emitted by the fiber tip section is sufficiently collimated.

[0025] In yet another embodiment of the body tissue treatment device according to the present invention, it comprises a light redirecting member as previously described herein, the collimator includes a plurality of optical fibers configured to guide the treatment light emitted by the light source to the light redirection member; the optical fiber has a fiber tip portion oriented perpendicular to the contact surface of the plate-shaped light output member; The optical fiber is configured to receive treatment light emitted by the light source and maintain the received treatment light at a numerical aperture in the range of 0.01 to 0.2.

[0026] In this further embodiment, the orientation of the fiber tip portions perpendicular to the contact surface of the plate-shaped light output member results in a first mean propagation direction of the collimated treatment light being perpendicular to the contact surface.

[0027] The present invention further provides a shaving unit for an electric shaver, comprising a base member, at least one hair-cutting unit supported by the base member, and at least one human tissue treatment device according to the present invention as described herein above, wherein a contact surface of a plate-shaped light output member of the human tissue treatment device is arranged relative to the hair-cutting unit such that the contact surface and the hair-cutting unit together contact the user's skin during use of the shaving unit. Thus, the human tissue treatment device can provide additional light treatment to the user's skin during use of the shaving unit, i.e., when the hair-cutting unit and the contact surface of the human tissue treatment device contact the user's skin, while the risk of eye damage due to the collimated treatment light generated by the human tissue treatment device is prevented during the period when the shaving unit is not in contact with the skin.

[0028] A preferred embodiment of the shaving unit according to the present invention further comprises a skin support member having a skin support surface at least partially surrounding the hair-cutting unit, and the human tissue treatment device is disposed on the skin support member such that the contact surface of the plate-shaped light output member of the human tissue treatment device forms part of the skin contact surface of the skin support member. This preferred embodiment provides a practical arrangement of the human tissue treatment device in the shaving unit, wherein the contact surface of the human tissue treatment device can at least partially surround the hair-cutting unit.

[0029] The present invention further provides an electric shaver having a main body and a shaving unit according to the present invention as described herein above, wherein said main body houses an electric motor and the shaving unit is arranged on the main body, so that a hair-cutting unit of the shaving unit is drivable by the electric motor.

[0030] These and other aspects of the present invention will be apparent from and elucidated with reference to the following detailed description of embodiments of a human tissue treatment device according to the present invention. [Brief explanation of the drawings]

[0031] [Figure 1] 1A to 1C are diagrams schematically illustrating top views of first, second and third embodiments of a human tissue treatment device according to the present invention. [Figure 2] 2 is a diagram schematically showing a cross section of the first embodiment of the human tissue treatment device taken along line II-II in FIG. 1. FIG. [Figure 3] 2A to 2C are diagrams schematically illustrating cross sections of collimator elements of collimators of the first, second, and third embodiments of the human tissue treatment device of FIG. 1. [Figure 4a] 2A and 2B are diagrams schematically illustrating propagation of treatment light in the light output member of the first and second embodiments of the human tissue treatment device of FIG. 1, in a state where the light output member is in contact with human tissue. [Figure 4b] 1. FIG. 4 is a diagram schematically illustrating propagation of treatment light in the light output member of the first and second embodiments of the human tissue treatment device of FIG. 1, when the light output member is not in contact with human tissue. [Figure 5] 1. FIG. 4 is a diagram schematically illustrating a cross section of a second embodiment of the human tissue treatment device taken along line VV in FIG. [Figure 6] 2 is a schematic diagram of a light source of the second embodiment of the body tissue treatment device of FIG. 1, along with associated light redirection elements. [Figure 7] 7 is a detailed schematic top view of the third embodiment of the body tissue treatment device designated by reference numeral VII in FIG. 1; FIG. [Figure 8]8A is a schematic cross-sectional view of the light output member and the light redirection member of the third embodiment of the body tissue treatment device taken along line VIII-VIII of FIG. 7. FIG. [Figure 9] FIG. 10 is a schematic cross-sectional view of a fourth embodiment of a human tissue treatment device according to the present invention. [Figure 10] FIG. 10 is a diagram schematically illustrating a top view of the human tissue treatment device of FIG. 9. [Figure 11] FIG. 10 is a diagram schematically illustrating a fifth embodiment of the human tissue treatment device according to the present invention. [Figure 12] 1 is a diagram showing a shaving unit of an electric shaver according to the present invention, which is provided with a human tissue treatment device according to the present invention; [Figure 13] 13 is a schematic cross-sectional view of the skin support member of the shaving unit taken along line XIII-XIII of FIG. 12. [Figure 14] 13 is a diagram showing a schematic top view of the human tissue treatment device of the shaving unit of FIG. 12. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0032] The invention will now be explained in more detail with reference to the figures, in which like or similar features are designated with the same reference numerals.

[0033] 1 and 2 schematically illustrate a first embodiment of a human tissue treatment device 1 according to the present invention. The human tissue treatment device 1 includes a housing 3 in which a plurality of light sources 5 are disposed. Each light source 5 is supported by a support member 6 disposed within the housing 3. Each light source 5 is configured to emit treatment light, and may comprise, for example, an LED. As shown in FIG. 2 , in the first embodiment, a separate collimator element 7 is associated with each individual light source 5 and configured and arranged to collimate the treatment light emitted by the individual light source 5. The collimator element 7 may be, for example, of the type schematically illustrated in FIG. 3 , which includes a solid body 9 made of an optically transparent material and having a central axis 11. The solid body 9 is circularly symmetrical about the central axis 11 and has a first end surface 13 and a second end surface 17 configured to receive treatment light 15 emitted by the light source 5 associated with the collimator element 7. The shapes of the first and second end faces 13, 17 and the outer peripheral surface 19 of the solid body 9 are such that, by refraction of the treatment light 15 at the first and second end faces 13, 17 and total internal reflection (TIR) ​​of the treatment light 15 at the outer peripheral surface 19, a collimated treatment light 21 having a first mean propagation direction PAV1 is established at the second end face 17. This method of light collimation is well known to those skilled in the art and will not be described in further detail. The collimator elements 7 together form a collimator 23 of the human tissue treatment device 1, which is constructed and arranged to collimate the treatment light 15 emitted by the light source 5, thereby establishing a collimated treatment light 21 having a first mean propagation direction PAV1.

[0034] As shown in FIGS. 1 and 2 , the human tissue treatment device 1 further includes a plate-shaped light output member 25 made of an optically transparent material. The outer major surface of the plate-shaped light output member 25 constitutes a contact surface 27 of the plate-shaped light output member 25, which is configured to contact human tissue during use of the human tissue treatment device 1. The inner major surface 29 of the plate-shaped light output member 25 has an average extension parallel to the contact surface 27 and is disposed opposite the contact surface 27 to receive the collimated treatment light 21. As will be described in detail below, the collimated treatment light 21 can be transmitted to human tissue through the plate-shaped light output member 25 and the contact surface 27 when the human tissue is in contact with the contact surface 27. The human tissue may be, for example, human skin, and the treatment light may include, for example, blue light or a combination of blue and red light at an intensity suitable for treating acne vulgaris. The combination of light intensity and duration of the treatment light suitable for treatment is well known to those skilled in the art and will not be described here. Other types of treatment of human skin, such as hair removal or hair growth inhibition, or treatment of other types of human tissue, such as gum tissue, may likewise be possible with the human tissue treatment device according to the invention.

[0035] As shown in Fig. 2, the inner main surface 29 of the plate-shaped light output member 25 includes an optical structure 31 having a plurality of pairs of first facets 33 and second facets 35. When viewed in cross section in Fig. 2, each of the first facets 33 is oriented at a first angle α1 with respect to the contact surface 27, and each of the second facets 35 is oriented at a second angle α2 with respect to the contact surface 27. In the illustrated embodiment, the respective first and second facets 33, 35 are connected to each other at their respective edges 37, 39. The first facets 33 are configured to receive the collimated treatment light 21 directly from the collimator 23, i.e., only through air present between the collimator 23 and the plate-shaped light output member 25. As a result, the second average propagation direction PAV2 of the collimated treatment light 21 at a position where the collimated treatment light 21 is incident on each individual first facet 33 is parallel to the first average propagation direction PAV1 of the collimated treatment light 21 emitted by the collimator element 7. As shown in Fig. 2, in this embodiment, each individual light source 5 and each individual collimator element 7 associated with the individual light source 5 are oriented obliquely with respect to the contact surface 27 of the plate-shaped light output member 25, so that the first and second average propagation directions PAV1 and PAV2 are inclined at an incident angle β with respect to the contact surface 27. As shown in Fig. 1, in this embodiment, the edges 37 and 39 of the first and second facets 33 and 35 extend linearly and parallel to each other, and in the line of sight direction perpendicular to the contact surface 27, the second average propagation direction PAV2 extends substantially perpendicular to the edges 37 and 39 of the first and second facets 33 and 35.

[0036] According to the present invention, the first angle α1 of the first facet 33, the second mean propagation direction PAV2, i.e., the incident angle β of the collimated treatment light 21 at the first facet 33 with respect to the contact surface 27, and the refractive index value n1 of the optically transparent material of the plate-shaped light output member 25 are expressed as follows: (i) the first facet 33 transmits the collimated treatment light 21 received by the first facet 33 to the plate-shaped light output member 25 by refraction; (ii) the contact surface 27 of the plate-shaped light output member 25 reflects the collimated treatment light received by the first facet 33 by total internal reflection (TIR) ​​at a position that does not contact human tissue; and (iii) The contact surface 27 of the plate-shaped light output member 25 is configured to transmit the collimated treatment light received by the first facet 33 from the plate-shaped light output member 25 to the human tissue by refraction at the contact position with the human tissue.

[0037] Furthermore, according to the present invention, the second facet 35 is configured to receive the collimated treatment light that is totally reflected at the contact surface 27 in accordance with the above-mentioned optical effect (ii), and the second angle α2 of the second facet 35 and the refractive index value n1 of the optically transparent material of the plate-shaped light output member 25 satisfy the following relationship: (iv) The second facet 35 transmits the collimated treatment light totally reflected at the contact surface 27 to the outside of the plate-shaped light output member 25 by refraction.

[0038] The combination of the above-mentioned optical effects (i) and (iii) is schematically shown in Fig. 4a for a pair of the first facet 33 and the second facet 35 of the optical structure 31, where the contact surface 27 is in contact with the human tissue 41. In Fig. 4a, the collimated treatment light 21 incident on the first facet 33 at an incident angle β with respect to the contact surface 27 is refracted by the first facet 33 and consequently propagates within the plate-shaped light output member 25 as collimated treatment light 21'. Because the contact surface 27 is in contact with the human tissue 41, the collimated treatment light 21' is transmitted from the plate-shaped light output member 25 to the human tissue 41 due to refraction at the contact surface 27.

[0039] The combination of the above-mentioned optical effects (i), (ii) and (iv) is schematically shown in Fig. 4b for a pair of the first facet 33 and the second facet 35 of the optical structure 31, where the contact surface 27 is not in contact with human tissue. In Fig. 4b, the collimated treatment light 21 incident on the first facet 33 at an incident angle β with respect to the contact surface 27 is refracted by the first facet 33 and consequently propagates within the plate-shaped light output member 25 as collimated treatment light 21'. Since the contact surface 27 is not in contact with human tissue, the collimated treatment light 21′ is totally reflected at the contact surface 27 and, as a result, further propagates within the plate-shaped light output member 25 as collimated treatment light 21″. The collimated treatment light 21″ is received by the second facet 35, is transmitted from the plate-shaped light output member 25 due to refraction at the second facet 35, and further propagates into the air outside the plate-shaped light output member 25 as collimated treatment light 21′″.

[0040] As described hereinabove, as a result of TIR of the collimated treatment light 21′ at the contact surface 27 when the contact surface 27 is not in contact with the human tissue 41, the treatment light emitted by the light source 5 is prevented from being emitted into the environment of the human tissue treatment device 1 through the contact surface 27 when the contact surface 27 is not covered by the human tissue 41. When the contact surface 27 is partially covered by the human tissue 41, the treatment light is prevented from being emitted into the environment of the human tissue treatment device 1 through the part of the contact surface 27 that is not covered by the human tissue 41. As a result, the treatment light emitted from the light source 5 is prevented from reaching parts that should not be treated, such as, for example, the eyes of a user of the human tissue treatment device 1 or parts of the human body, particularly skin tissue. Furthermore, the collimated treatment light 21" internally reflected at the contact surface 27 is transmitted from the plate-shaped light output member 25 due to refraction at the second facet 35, thereby limiting absorption of the treatment light by the plate-shaped light output member 25 and the resulting heating of the plate-shaped light output member 25. The collimated treatment light 21''' transmitted from the plate-shaped light output member 25 via the second facet 35 can be absorbed by the housing 3 or other parts (not shown) of the human tissue treatment device 1 arranged within the housing 3, thereby limiting heating of the plate-shaped light output member 25.

[0041] The collimated treatment light 21 is received by the optical structure 31 disposed on the inner main surface 29 of the plate-shaped light output member 25 and is transmitted into the plate-shaped light output member 25 by refraction at the first facet 33 of the optical structure 31. This means that a relatively large amount of collimated treatment light can be received by the inner main surface 29 of the plate-shaped light output member 25 and transmitted to the human tissue 41 via the contact surface 27 without substantial loss of light intensity. In the first embodiment, the light sources 5 can be disposed at a relatively short distance below the plate-shaped light output member 25, thereby reducing the required volume of the human tissue treatment device 1 below the plate-shaped light output member 25. When the light sources 5 are regularly distributed over the entire area of ​​the plate-shaped light output member 25, for example, when the light sources 5 are distributed based on a regular 2D array as shown in FIG. 1 , a uniform light intensity at the contact surface 27 can be achieved despite the relatively short distance between the light sources 5 and the plate-shaped light output member 25. It should be noted that the number of light sources 5 and the number of first and second facets 33, 35 of the optical structure 31 shown in FIG. 1 are purely exemplary. A person skilled in the art would also be able to easily determine the number and distribution of light sources 5 required to obtain a desired level of uniformity of light intensity at the contact surface 27. When viewed in cross section in FIG. 2, a single light source 5 can be associated with a pair of first and second facets 33, 35. Alternatively, as shown in FIG. 2, a single light source 5 can be associated with two or more pairs of first and second facets 33, 35. In this context, a person skilled in the art would also be able to easily determine the number and dimensions of the first and second facets 33, 35, particularly as viewed in cross section in FIG. 2.

[0042] In the most preferred embodiment of the human tissue treatment device according to the present invention, the optical structure 31 of the plate-shaped light output member 25 can have multiple pairs of first facets 33 and second facets 35, but in some embodiments, particularly in embodiments in which the contact surface 27 of the plate-shaped light output member 25 has a relatively small area, the optical structure can have only one pair of first facets 33 and second facets. It will be clear to those skilled in the art that for a given area of ​​the contact surface 27, the number of pairs of first and second facets 33, 35 can be reduced by increasing the dimensions of the first and second facets 33, 35. However, the increased dimensions of the first and second facets 33, 35 result in an increased height (thickness) of the optical structure 31 perpendicular to the contact surface 27, and consequently, an increased thickness of the plate-shaped light output member 25.

[0043] Furthermore, based on the description of the optical effect of the optical structure 31 detailed above, a person skilled in the art will be able to easily determine any suitable values ​​for the first angle α1, the second angle α2, the second average propagation direction PAV2 (i.e., the incident angle β) of the collimated treatment light 21 relative to the contact surface 27 at the first facet 33, and the refractive index value n1 of the optically transparent material of the plate-shaped light output member 25, for example, based on Snell's law of optical refraction and the critical incident angle of TIR, which can be calculated using Snell's law.

[0044] The refractive index value n1 is preferably in the range of 1.4 to 1.7. For example, when n1=1.5, TIR occurs at the contact surface 27 if the incident angle β of the collimated treatment light 21′ propagating through the plate-shaped light output member 25 (see FIG. 4a) with respect to the contact surface 27 is approximately 48° or less. When the first facet 33 is oriented perpendicular to the second average propagation direction PAV2, the first angle α1 may be approximately 42° or more, and the incident angle β of the collimated treatment light 21 with respect to the contact surface 27 at the first facet 33 may be approximately 48° or less. By utilizing the effect of light refraction of the collimated treatment light 21 at the first facet 33, the angle α1 may be smaller than approximately 42°, and the incident angle β may be larger than 48°. In this case, the second average propagation direction PAV2 is generally oriented transversely to the first facet 33, but not perpendicularly. This results in a more favorable position of the light source 5 relative to the plate-shaped light output member 25 .

[0045] It is clear to those skilled in the art that, based on Snell's law, a higher refractive index n1 results in a higher incident angle β of the collimated treatment light 21 at the first facet 33 and a lower angle α1, and thus in a more suitable position of the light source 5 relative to the plate-shaped light output member 25. Suitable materials for the plate-shaped light output member 25 that provide a refractive index n1 in the range of 1.4 to 1.7 are, for example, polymethyl methacrylate (PMMA), polycarbonate, glass, or quartz glass. By using a material with a refractive index n1>1.7, such as sapphire, an even higher incident angle β of the collimated treatment light 21 at the first facet 33 can be realized.

[0046] Based on the requirement that the incident angle β of the collimated treatment light 21″ internally reflected at the contact surface 27 (see FIG. 4b ) to the second facet 35 must be greater than the critical incident angle at which TIR occurs at the second facet 35, the angle α2 of the second facet 35 can be determined in a straightforward manner. Based on Snell's law, when n1=1.5, the incident angle β should be greater than about 48°. In practice, this results in the angle α2 being relatively small, which minimizes the required thickness of the optical structure 31 viewed perpendicularly to the contact surface 27.

[0047] Furthermore, the degree of collimation of the collimated treatment light 21 by the collimator 23 can be taken into consideration when determining the first angle α1, the second angle α2, the incident angle β of the collimated treatment light 21 on the first facet 33, and the refractive index value n1. In practice, the rays of the collimated treatment light 21 are not completely parallel, that is, the collimated treatment light 21 also slightly diverges. Based on the degree of divergence of the collimated treatment light 21, the first angle α1, the second angle α2, the incident angle β of the collimated treatment light 21 on the first facet 33, and the refractive index value n1 can be determined so that the collimated treatment light 21′ propagating within the plate-shaped light output member 25 is totally reflected at the contact surface 27 when the contact surface 27 is not in contact with the human tissue 41, or at least a large portion of the collimated treatment light 21′ is internally reflected at the contact surface 27 to an extent that eye-safety is achieved.

[0048] Figures 1 and 5 show a schematic representation of a second embodiment of a human tissue treatment device 101 according to the present invention. In the cross section of Figure 5, features of the human tissue treatment device 101 that are identical and correspond to features of the first embodiment of the human tissue treatment device 1 described in detail hereinbefore are indicated by corresponding reference numerals. In the following, such identical and corresponding features will not be described in detail, but only the main different features of the human tissue treatment device 101 will be described in detail.

[0049] Similar to the first embodiment of the human tissue treatment device 1, the human tissue treatment device 101 includes a plurality of light sources 5 (e.g., LEDs) arranged on a support member 6 within a housing 3 and configured to emit treatment light. Similar to the human tissue treatment device 1, the human tissue treatment device 101 includes a collimator 23 having an individual collimator element 7 for each individual light source 5, configured and arranged to collimate the treatment light emitted by the individual light source 5. Each of the collimator elements 7 may be of the type shown in FIG. 3 and described in detail herein. Meanwhile, in the human tissue treatment device 1, the second mean propagation direction PAV2 of the collimated treatment light 21 at the first facet 33 of the optical structure 31 of the plate-shaped light output member 25 is parallel to the first mean propagation direction PAV1 of the collimated treatment light 21 emitted by the collimator elements 7, and in the human tissue treatment device 101, the first mean propagation direction PAV1 is different from the second mean propagation direction PAV2. In particular, as shown in Fig. 5, the light source 5 and the associated collimator element 7 are mounted on the support member 6 such that the first mean propagation direction PAV1 is substantially perpendicular to the contact surface 27 of the plate-shaped light output member 25. To redirect the collimated treatment light 21 emitted by the collimator element 7 from the first mean propagation direction PAV1 to the second mean propagation direction PAV2, the human tissue treatment device 101 comprises a separate light redirecting element 43 for each individual light source 5, which is arranged in an air-filled space 45 between the collimator element 7 associated with the individual light source 5 and the plate-shaped light output member 25. In the second embodiment as shown in Fig. 5, each light redirecting element 43 comprises a mirror 47, which is only schematically shown in Fig. 5 and can be attached to the associated collimator element 7 or to a suitable support structure (not shown in Fig. 5) for all mirrors 47. Alternatively, each light redirecting element 43 can comprise a prism 49. FIG. 6 shows a schematic representation of one of the light sources 5 of the body tissue treatment device 101 together with the associated collimator element 7 and the associated light redirecting prism 49 .

[0050] In the second embodiment of the human tissue treatment device 101, the light redirecting elements 43 together form a light redirecting member 51 of the human tissue treatment device 101, which is disposed between the collimator 23 and the plate-shaped light output member 25 and configured to redirect the collimated treatment light 21 emitted by the collimator 23 from a first mean propagation direction PAV1 to a second mean propagation direction PAV2. Generally, the use of the light redirecting member 51 allows the first mean propagation direction PAV1 of the collimated treatment light 21 emitted by the collimator 23 to be different from the second mean propagation direction PAV2 of the collimated treatment light 21 at the position where the collimated treatment light 21 is received by the first facet 33 of the optical structure 31 of the plate-shaped light output member 25. This allows the light source 5 to be positioned in any practical orientation on the support member 6. For example, the support member 6 may be a printed circuit board (PCB), and the light source 5 may be an LED mounted in a normal upright position on the PCB.

[0051] 1 is similar to the second embodiment of the human tissue treatment device 101 described herein above, and has a plurality of light sources 5 and associated collimator elements 7, where each light source 5 (e.g., LED) and its associated collimator element 7 is arranged on the support member 6 (e.g., PCB) such that a first average propagation direction PAV1 of the collimated treatment light 21 emitted by the collimator element 7 is substantially perpendicular to the contact surface 27 of the plate-shaped light output member 25. The main difference between the human tissue treatment device 201 according to the third embodiment and the human tissue treatment device 101 according to the second embodiment is that in the human tissue treatment device 201, the light redirecting elements 43 used in the human tissue treatment device 101 are replaced by a single light redirecting member 53 (see FIG. 8 ) common to all light sources 5. The light redirecting member 53 of the human tissue treatment device 201 comprises a plate-shaped carrier 55 made of an optically transparent material and arranged parallel to and adjacent to the inner main surface 29 of the plate-shaped light output member 25. The plate-shaped carrier 55 of the light redirecting member 53 is partially visible in Figure 7, which only schematically shows a detail of a top view of the human tissue treatment device 201 designated by reference numeral VII in Figure 1, and in Figure 8, which schematically shows a cross section of the plate-shaped light output member 25 and the plate-shaped carrier 55 of the light redirecting member 53 along line VIII-VIII in Figure 7. Although the plate-shaped carrier 55 is not completely visible in Figures 7 and 8, it should be understood that the plate-shaped carrier 55 extends along the entire area of ​​the plate-shaped light output member 25.

[0052] 8 , a first main surface 57 of the plate-shaped carrier 55 of the light redirecting member 53, facing away from the plate-shaped light output member 25, is flat and extends parallel to the contact surface 27 of the plate-shaped light output member 25. The first main surface 57 of the plate-shaped carrier 55 is configured to receive the collimated treatment light 21 emitted by the collimator element 7 (not shown) and having a first mean propagation direction PAV1, and to transmit the collimated treatment light 21 into the plate-shaped carrier 55.

[0053] A second main surface 59 of the plate-shaped carrier 55 of the light redirecting member 53, facing the plate-shaped light output member 25, comprises an optical structure 61 having a plurality of pairs of third facets 63 and fourth facets 65. When viewed in cross section in Figure 8, each of the third facets 63 is oriented at a third angle α3 relative to the first main surface 57, and each of the fourth facets 65 is oriented at a fourth angle α4 relative to the first main surface 57. In the illustrated embodiment, the respective third and fourth facets 63, 65 are connected to each other at respective edges 67, 69 of the third and fourth facets 63, 65. As shown in Figure 7, the edges 67, 69 of the third and fourth facets 63, 65 of the optical structure 61 of the light redirecting member 53 extend linearly, parallel to each other and to the edges 37, 39 of the first and second facets 33, 35 of the optical structure 31 of the plate-shaped light output member 25. Although the third and fourth facets 63, 65 are not fully visible in Figures 7 and 8, it should be understood that the third and fourth facets 63, 65 extend along the entire extension of the first and second facets 33, 35, and that each individual pair of first and second facets 33, 35 of the optical structure 31 of the plate-shaped light output member 25 is associated with an individual pair of third and fourth facets 63, 65 of the optical structure 61 of the light redirecting member 53 in a manner similar to that shown schematically in Figures 7 and 8.

[0054] 8 , the third facet 63 of the optical structure 61 of the light redirecting member 53 is configured to receive the collimated treatment light 221′ transmitted by the first main surface 57 of the plate-shaped carrier 55. In this embodiment, the third angle α3, the first mean propagation direction PAV1 of the collimated treatment light 21 incident on the first main surface 57, and the refractive index value n2 of the optically transparent material of the plate-shaped carrier 55 are such that the third facet 63, by refraction, transmits the collimated treatment light 221′ from the plate-shaped carrier 55 and redirects it into the second mean propagation direction PAV2 toward the first facet 33 of the plate-shaped light output member 25. For a given value of the first mean propagation direction PAV1 of the collimated treatment light 21 emitted by the collimator element 7, a person skilled in the art can determine, based on e.g. Snell's law of optical refraction, the third angle α3 and the optical transparency of the plate-shaped carrier 55 required to achieve any desired value of the second mean propagation direction PAV2 of the collimated treatment light 221″ at the first facet 33, i.e. the angle of incidence β of the collimated treatment light 21, as explained in detail herein with respect to the first embodiment of the device for treating human tissue 1. Any suitable value for the refractive index value n2 of the material may be determined in an easy-to-understand manner. As in the human tissue treatment device 201 of the third embodiment, when the first mean propagation direction PAV1 is perpendicular to the first main surface 57 of the plate-shaped carrier 55, the refractive index value n2 is, for example, 1.5, and the third angle α3 is about 40°, the collimated treatment light 221″ is transmitted from the plate-shaped carrier 55 by the third facet 63 into the second mean propagation direction PAV2 with an incident angle β of about 55° with respect to the contact surface 27. It is obvious to those skilled in the art that the incident angle β can be reduced by increasing the refractive index value n2 and / or the third angle α3.

[0055] The light redirecting member 53 has a compact structure, which, together with the plate-shaped light output member 25 arranged immediately adjacent to and parallel to the light redirecting member 53, results in a practical and compact overall structure of the human tissue treatment device 201. The collimated treatment light 21 emitted by the collimator element 7 is received by the first main surface 57 of the plate-shaped carrier 55 and transmitted and redirected by refraction at the third facet 63 provided on the second main surface 59 of the plate-shaped carrier 55, so that the light redirecting member 53 enables a large amount of the collimated treatment light 21 to be transmitted and redirected from the first mean propagation direction PAV1 to the second mean propagation direction PAV2 without substantial loss of light intensity.

[0056] In the third embodiment of the human tissue treatment device 201 according to the present invention, the optical structure 61 of the light redirecting member 53 has a plurality of pairs of third facets 63 and fourth facets 65, but in some embodiments, especially in embodiments in which the contact surface 27 of the plate-shaped light output member 25 has a relatively small area, the optical structure of the light redirecting member can have only one pair of third facets and fourth facets. It will be apparent to those skilled in the art that for a given area of ​​the contact surface 27, the number of pairs of third and fourth facets 63, 65 can be reduced by increasing the dimensions of the third and fourth facets 63, 65. However, the increased dimensions of the third and fourth facets 63, 65 result in an increased height (thickness) of the optical structure 61 perpendicular to the contact surface 27, and consequently, an increased thickness of the light redirecting member 53.

[0057] Preferably, as in the third embodiment schematically shown in Fig. 8, the third angle α3 of the third facet 63 of the light redirecting member 53 is equal to the second angle α2 of the second facet 35 of the plate-shaped light output member 25, and the fourth angle α4 of the fourth facet 65 of the light redirecting member 53 is equal to the first angle α1 of the first facet 33 of the plate-shaped light output member 25. As a result, the optical structure 31 on the inner main surface 29 of the plate-shaped light output member 25 and the optical structure 61 on the second main surface 59 of the light redirecting member 53 may be identical, so that in practice, the plate-shaped light output member 25 and the plate-shaped light redirecting member 53 may be identical, and the plate-shaped light redirecting member 53 is arranged in an inverted state with respect to the plate-shaped light output member 25, as shown in Fig. 8. This results in a simple and compact structure of the human tissue treatment device 201. The condition that the third angle α3 is equal to the second angle α2 and the fourth angle α4 is equal to the first angle α1 can be obtained without affecting the desired optical effect of the plate-shaped light output member 25 and the light redirecting member 53, because the fourth facet 65 does not play a dominant role in the optical function of the light redirecting member 53 (i.e., the fourth angle α4 is not important), and the range of acceptable values ​​for the second angle α2 is relatively wide in practice.

[0058] The human tissue treatment devices 1, 101, 201 according to the first, second, and third embodiments of the present invention described above each have multiple light sources 5 arranged at a relatively short distance below the plate-shaped light output member 25 to provide uniform light intensity to the contact surface 27. This results in a relatively compact structure for the human tissue treatment devices 1, 101, 201. The present invention also covers embodiments in which one or more light sources are arranged at a relatively large distance below the plate-shaped light output member to provide uniform light intensity to the contact surface of the plate-shaped light output member with a single light source or a small number of light sources. In these embodiments, for example, if the human tissue treatment device is intended to treat a relatively small area of ​​human tissue, such as an individual pimple on human skin, the size of the human tissue treatment device is not a critical design factor, or the contact surface of the plate-shaped light output member can have a relatively small area.

[0059] As shown schematically in Figures 9 and 10, a fourth embodiment of a human tissue treatment device 301 according to the present invention is an acne treatment device having an elongated housing 303 and a contact surface 327 with a circular periphery located at the upper end of the housing 303. The contact surface 327 can have a relatively small area suitable for treating a single or a relatively small number of acne breakouts simultaneously. The elongated housing 303 has a central axis 371 extending perpendicular to the contact surface 327, and the elongated housing 303 is substantially circularly symmetrical about the central axis 371. The human tissue treatment device 301 has a single light source 305 (e.g., an LED) located on the central axis 371 near the lower end of the housing 303, i.e., at a relatively large distance from the contact surface 327. The light source 305, which is only shown schematically in Figure 9, is configured to emit treatment light 321 having an average emission direction perpendicular to the contact surface 327. Alternatively, a small number of light sources (eg, LEDs) may be arranged near the bottom end of the housing 303 in a tightly packed annular arrangement around the central axis 371 .

[0060] The body tissue treatment device 301 further includes an elongated light guide 373 extending within the elongated housing 303 between the light source 305 and the contact surface 327. The light guide 373 has a central axis that coincides with the central axis 371 of the housing 303 and accordingly extends perpendicular to the contact surface 327. The light guide 373 functions as a collimator 323 of the body tissue treatment device 301 and has a first end face 375 configured to receive the treatment light 321 emitted by the light source 305 and a second end face 377 configured to emit collimated treatment light 321' toward the contact surface 327. In this embodiment, the light guide 373 includes a bulk light guide body 379 made of an optically transparent material, such as plastic, sapphire, crystal glass, or fused silica. The light guide body 379 is separated from the housing 303 by an air gap and may have a reflective coating on its circumferential surface 381. The light guide body 379 is circularly symmetric about the central axis 371 and has a cross-sectional area perpendicular to the central axis 371 that gradually increases from the first end face 375 to the second end face 377, as shown in Figure 9. As a result, the light guide 373 is configured to collimate the treatment light 321 received at the first end face 375 by total internal reflection (TIR) ​​of the received treatment light at a circumferential surface 381 of the light guide body 379 and by reflection of the received treatment light at a reflective coating (if present) on the circumferential surface 381.

[0061] Alternatively, the light guide may have a hollow light guide channel (not shown) configured to collimate the treatment light received at the first end face by reflecting the received treatment light off a reflective coating provided on the inner surface of the light guide channel.

[0062] As a result of the circularly symmetric shape of the light guide body 379, the gradually increasing cross-sectional area of ​​the light guide body 379 in the direction from the first end face 375 to the second end face 377, the central location of the light source 305 on the central axis 371, and the average emission direction of the light source 305 perpendicular to the contact surface 327, the light guide 373 provides a relatively high degree of collimation of the collimated treatment light 321′ emitted at the second end face 377. Furthermore, the degree of collimation and the light intensity of the emitted collimated treatment light 321′ are very uniform across the cross section of the second end face 377 of the light guide 373. The light guide 373 constitutes a very practical and structurally simple embodiment of the collimator 323. The first average propagation direction PAV1 of the collimated treatment light 321′ emitted by the collimator 323 is substantially perpendicular to the contact surface 327.

[0063] 9 , the human tissue treatment device 301 further includes a plate-shaped light output member 325 including a contact surface 327, and a light redirecting member 353 having a plate-shaped carrier 355 disposed directly below and parallel to the plate-shaped light output member 325. The light redirecting member 353 is configured to receive collimated treatment light 321′ emitted by the collimator 323 and having a first mean propagation direction PAV1, and redirect the collimated treatment light 321′ from the first mean propagation direction PAV1 to a second mean propagation direction PAV2 toward the plate-shaped light output member 325. In short, the configurations and optical effects of the plate-shaped light output member 325 and the light redirecting member 353 are similar to the configurations and optical effects of the plate-shaped light output member 25 and the light redirecting member 53 in the human tissue treatment device 201 of the third embodiment described in detail herein. That is, the plate-shaped light output member 325 has an optical structure 331 similar to the optical structure 31 of the plate-shaped light output member 25, and the light redirecting member 353 has an optical structure 361 similar to the optical structure 61 of the light redirecting member 53. The difference is that the plate-shaped light output member 25 and the light redirecting member 53 have rectangular peripheral edges, while the plate-shaped light output member 325 and the light redirecting member 353 have circular peripheral edges 383, 385 arranged concentrically about a central axis 371, as shown in Figure 10 . Furthermore, the first and second facets 33, 35 of the optical structure 31 of the plate-shaped light output member 25 and the third and fourth facets 63, 65 of the optical structure 61 of the light redirecting member 53 extend linearly and parallel to each other, while the corresponding first and second facets 333, 335 of the corresponding optical structure 331 of the plate-shaped light output member 325 and the corresponding third and fourth facets 363, 365 of the corresponding optical structure 361 of the light redirecting member 353 are annular and extend concentrically about the central axis 371. For simplicity, the optical structures 331 and 361 are not shown in detail in Figure 9 and will be further described below with reference to Figures 8 and 10.

[0064] 9, an air gap exists between the second end surface 377 of the light guide 373 and the first major surface 357 of the light redirecting member 353. Alternatively, the first major surface 357 of the light redirecting member 353 may be in direct optical contact with the second end surface 377 of the light guide 373.

[0065] In the top view of the human tissue treatment device 301 of FIG. 10, the annular extensions of the first, second, third and fourth facets 333, 335, 363, 365 are indicated generally by only two circular dashed lines C1, C2, while a few pairs of the first and second facets 333, 335 and their circular edges 337, 339, and portions of pairs of the third and fourth facets 363, 365 and their circular edges 367, 369 are shown in more detail in the detailed top view DTV of FIG. 10. Those skilled in the art will understand that, as a result of the annular extension of the first, second, third and fourth facets 333, 335, 363, 365 around the central axis 371, a cross section of the plate-shaped light output member 325 and the light redirecting member 353 taken along any radial line RR, as shown in Figure 10, will be similar to the cross section of the plate-shaped light output member 25 and the light redirecting member 53 of the body tissue treatment device 201, as shown schematically in Figure 8. Therefore, for a more detailed description of the shape and optical effect of the first, second, third and fourth facets 333, 335, 363, 365, reference is made to the above description of the shape and optical effect of the corresponding first, second, third and fourth facets 33, 35, 63, 65 of the body tissue treatment devices 1 and 201. Those skilled in the art will understand that the circular extension of the first, second, third and fourth facets 333, 335, 363, 365 does not fundamentally change the optical effect compared to the first, second, third and fourth facets 33, 35, 63, 65 of the human tissue treatment device 1, 201 as previously described herein. In particular, those skilled in the art will understand that in the viewing direction in FIG. 10 perpendicular to the contact surface 327, the second mean propagation direction PAV2 locally extends substantially perpendicular to the circular edges 337, 339, 367, 369 of the first, second, third and fourth facets 333, 335, 363, 365, i.e., the second mean propagation direction PAV2 locally extends in a radial plane extending through the central axis 371.

[0066] In a fifth embodiment of a human tissue treatment device 401 according to the invention, a single light source 405 is arranged at a relatively large distance from a plate-shaped light output member 425 having a contact surface 427. Treatment light emitted by the light source 405 is guided to the plate-shaped light output member 425 and distributed over the area of ​​the plate-shaped light output member 425 by a plurality of optical fibers 473. The human tissue treatment device 401 is only shown schematically in Figure 11 and will be described hereinafter only in general terms.

[0067] The human tissue treatment device 401 further comprises a light redirecting member 453. The plate-shaped light output member 425 and the light redirecting member 453 may be similar to the plate-shaped light output member 325 and the light redirecting member 353 of the human tissue treatment device 301, as described in detail above, and may be disposed accordingly within a cylindrical housing 403 of the human tissue treatment device having a central axis 471. Alternatively, the plate-shaped light output member 425 and the light redirecting member 453 may be similar to the plate-shaped light output member 25 and the light redirecting member 53 of the human tissue treatment device 201, as described in detail above. In this case, the housing 403 may have a square or rectangular cross-section perpendicular to the central axis 471. The light source 405 may be disposed in any suitable position within the housing 403, and the optical fibers 473 may be bundled into a bundle 475 extending through the housing 403 from the light source 405 to the light redirecting member 453. Alternatively, the housing 403 may constitute a treatment handpiece of the human tissue treatment device 401, and the light source 405 may be located in a base station of the human tissue treatment device 401 connected to the treatment handpiece by a flexible cable containing a bundle 475 of optical fibers 473.

[0068] Those skilled in the art will be able to readily determine the number and distribution of optical fibers 473 required to achieve the desired uniformity of the light intensity of the treatment light at the contact surface 427. In this regard, the number of optical fibers 473 shown in FIG. 11 is purely schematic and exemplary. Furthermore, the optical fibers 473 may function as collimators for the treatment light 421 emitted by the fiber tip portions 477 of the optical fibers 473 toward the light redirection member 453. For this purpose, the optical fibers 473 are preferably configured to receive the treatment light emitted by the light source 405 and maintain the received treatment light at a numerical aperture (NA) value in the range of 0.01 to 0.2. As is generally known to those skilled in the art, the numerical aperture can be limited to a value within the above range by applying a relatively low NA incoupling of the treatment light into the optical fibers 473 at the light source 405 and / or by using appropriate optical properties of the optical fibers 473, in particular the fiber core material and / or the fiber cladding material. As also known to those skilled in the art, an additional collimator element, such as a ball lens or a microlens (not shown in FIG. 11), can be placed near the fiber tip portion 477 to collimate the treatment light emitted by the fiber tip portion 477.

[0069] 11 , the fiber tip portion 477 of the optical fiber 473 is oriented perpendicular to the contact surface 427 of the plate-shaped light output member 425, such that a first mean propagation direction PAV1 of the collimated treatment light 421 emitted by the fiber tip portion 477 is perpendicular to the contact surface 427. The light redirecting member 453 is configured to redirect the collimated treatment light 421 from the first mean propagation direction PAV1 to a second mean propagation direction PAV2 (not shown in FIG. 11 ) toward the plate-shaped light output member 425 in a manner similar to the light redirecting member 353 of the human tissue treatment device 301 described in detail earlier in this document.

[0070] Alternatively, the light redirecting member 453 of the human tissue treatment device 401 according to the fifth embodiment can be omitted, and the fiber tip portion 477 of the optical fiber 473 can be oriented in an oblique direction with respect to the contact surface 427 of the plate-shaped light output member 425, so that the first mean propagation direction PAV1 of the collimated treatment light 421 emitted by the fiber tip portion 477 is parallel to the second mean propagation direction PAV2 of the collimated treatment light 421 received by the optical structure 431 of the plate-shaped light redirecting member 425. Therefore, in this alternative embodiment, the optical fiber 473 is configured to directly guide the treatment light emitted by the light source 405 to the plate-shaped light output member 425.

[0071] Each of the body tissue treatment devices 1, 101, 201, 301, and 401 according to the present invention described herein may be embodied as a so-called stand-alone device, where treatment of the body tissue with collimated treatment light provided to the contact surface 27, 327, and 427 is the only or primary treatment provided by the body tissue treatment device 1, 101, 201, 301, and 401. The body tissue treatment device according to the present invention may also be embodied as a treatment unit of a multifunctional treatment system having a main body and a plurality of different treatment units that can be selectively coupled to the main body by a user. One example is a personal care system for treating human skin, having a main body and a plurality of different personal care units that can each be selectively coupled to the main body, where the personal care units include, for example, a shaving unit, a hair trimming unit, a brushing unit, a face washing unit, and a light treatment unit embodied as the body tissue treatment device according to the present invention for the treatment of acne or other skin disorders.

[0072] The human tissue treatment device according to the present invention can also be integrated as a secondary treatment unit of a main treatment device, where the human tissue treatment device is disposed within the main treatment device and provides collimated treatment light to the human tissue in conjunction with the main treatment provided by the main treatment device. One example is a shaving unit 501 of an electric shaver according to the present invention, as shown in FIG. 12. The shaving unit 501 has a base member 502 supporting at least one hair-cutting unit 503, three hair-cutting units 503 in this example. Each hair-cutting unit 503 has a rotatable external cutting member 504 having an annular shaving area 505 with a plurality of hair entry openings (not shown in detail), and an internal cutting member (not shown) enclosed by the external cutting member 504 and rotatable within the external cutting member 504. Such hair-cutting units are well known to those skilled in the art, and will not be described in further detail below. The shaving unit 501 can be arranged on the body of the electric shaver (not shown), which, as is well known to those skilled in the art, houses an electric motor and a transmission system, through which the electric motor can rotate and drive the internal cutting member of the hair-cutting unit 503 within the external cutting member 504 in order to cut hair that has entered the external cutting member 504 through a hair entry opening in the annular shaving area 505.

[0073] Each hair-cutting unit 503 of the shaving unit 501 is at least partially surrounded by a skin support member 506. Each skin support member 506 has a skin-contacting surface 507 that is configured to contact the skin together with the external cutting member 504 of the hair-cutting unit 503 during the shaving process. In the embodiment shown in FIG. 12, each individual skin support member 506 and its skin-contacting surface 507 completely surrounds the hair-cutting unit 503 associated with the individual skin support member 506. Each individual skin support member 506 has a human tissue treatment device 511 according to the present invention disposed in a C-shaped recess 508 provided in the individual skin support member 506, as shown in FIG. 12. Notably, in this example, each human tissue treatment device 511 is embodied similarly to the third embodiment of the human tissue treatment device 201 described previously herein, with the main difference being that each human tissue treatment device 511 only has a single C-shaped array of light sources 515 (e.g., LEDs). FIG. 12 shows how, for each individual skin support member 506 , the light source 515 of the associated body tissue treatment device 511 is configured, along with an associated collimator element 517 , within a C-shaped recess 508 of the individual skin support member 506 .

[0074] 12 does not show the plate-shaped light output member 525 and the light redirecting member 553 of the human tissue treatment device 511 in order to visualize the light source 515. One plate-shaped light output member 525 and one light redirecting member 553 of the human tissue treatment device 511 are visible in FIG. 13, which schematically shows a cross section of one of the skin support members 506 extending perpendicular to the skin contact surface 507 through line XIII-XIII in FIG. 12. As shown in FIG. 13, for each individual skin support member 506, the contact surface 527 of the plate-shaped light output member 525 of the associated human tissue treatment device 511 forms part of and is flush with the skin contact surface 507 of the individual skin support member 506. Although not shown in FIG. 12, it will be apparent to those skilled in the art that each plate-shaped light output member 525 is C-shaped in order to completely cover the C-shaped recess 508 of the associated skin support member 506.

[0075] Two pairs of first and second facets 533, 535 and their edges 537, 539 of the plate-shaped light output member 525, and two pairs of third and fourth facets 563, 565 and their edges 567, 569 of the light redirecting member 553 are shown schematically in the top view of one of the body tissue treatment devices 511 of the shaving unit 501 in Figure 14. The number of facets and the distances between them in Figure 14 are purely exemplary and schematic. As shown in Figure 14, the edges 537, 539, 567, 569 of the first, second, third and fourth facets 533, 535, 563, 565, respectively, extend radially relative to the central axis 571 of the C-shaped light output member 525. Therefore, a person skilled in the art will understand that a cross section of the plate-shaped light output member 525 and the light redirecting member 553 taken along the partial circular line TT as shown in Figure 14 is similar to the cross section of the plate-shaped light output member 25 and the light redirecting member 53 of the third embodiment of the human tissue treatment device 201 as shown schematically in Figure 8. Therefore, for a more detailed description of the shape and optical effect of the first, second, third and fourth facets 533, 535, 563, 565, reference is made to the description herein above regarding the shape and optical effect of the corresponding first, second, third and fourth facets 33, 35, 63, 65 of the human tissue treatment device 1, 201. Those skilled in the art will understand that the radial extension of the first, second, third and fourth facets 533, 535, 563, 565 does not fundamentally change the optical effect compared to the first, second, third and fourth facets 33, 35, 63, 65 of the body tissue treatment device 1, 201 as previously described herein. In particular, those skilled in the art will understand that in the viewing direction in FIG. 14 perpendicular to the contact surface 527, the second mean propagation direction P AV2 extends locally substantially perpendicular to the edges 537, 539, 567, 569 of the first, second, third and fourth facets 533, 535, 563, 565, as shown schematically in FIG.

[0076] During shaving with the shaving unit 501, the contact surface 527 of the human tissue treatment device 511 disposed on the skin support member 506 of the shaving unit 501 contacts the user's skin together with the hair-cutting unit 503. As a result, the collimated treatment light 521 emitted by the collimator element 517 of the light source 515 is transmitted to the skin via the light redirecting member 553 and the plate-shaped light output member 525 of the human tissue treatment device 511 during the shaving process. The collimated treatment light 521 provides light treatment to the skin during the shaving process, where the type of treatment depends on the combination of light intensity and wavelength of the collimated treatment light 521, as known to those skilled in the art.

[0077] The scope of the present invention is not limited to the embodiments and examples described hereinabove, and several modifications and changes are possible without departing from the scope of the present invention as defined in the claims. The present invention is intended to be construed as including all such modifications and changes insofar as they fall within the scope of the claims. Although the present invention has been illustrated and described in detail in the drawings and description, such illustration and description are merely explanatory or exemplary and not restrictive. The drawings are schematic, in which details not necessary for understanding the invention may be omitted and are not necessarily drawn to scale.

[0078] Variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the figures, the description, and the claims. In the claims, the word "comprising" does not exclude other steps or elements, and the indefinite article "a" or "an" does not exclude a plurality. Any reference signs in the claims should not be construed as limiting the scope of the invention.

[0079] Elements and aspects discussed for or in connection with a particular embodiment can be combined with elements and aspects of other embodiments as appropriate, unless otherwise expressly stated. Thus, the mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

Claims

1. A human body tissue treatment device, comprising: a housing; at least one light source disposed within the housing and emitting treatment light; a collimator configured to collimate the treatment light emitted by the light source to establish collimated treatment light having a first mean propagation direction; and a plate-shaped light output member made of an optically transparent material and having a contact surface, through which the collimated treatment light can be transmitted to the human body tissue when the human body tissue is in contact with the contact surface; an inner surface of the plate-shaped light output member opposite to the contact surface includes an optical structure having one or more pairs of first and second facets, the first and second facets being oriented at a first angle α1 and a second angle α2, respectively, with respect to the contact surface; the first facets receive the collimated treatment light, and at a location where the collimated treatment light is incident on each respective first facet, the collimated treatment light has a second mean propagation direction; the first angle α1, the second mean propagation direction, and the refractive index value n1 of the optically transparent material of the plate-shaped light output member are such that (i) the first facet transmits the received treatment light into the plate-shaped light output member by refraction; (ii) the contact surface reflects the received treatment light by total internal reflection at a position not in contact with human tissue; and iii) the contact surface transmits the received treatment light from the plate-shaped light output member into human tissue by refraction at a position in contact with human tissue, the second facet receives the treatment light reflected by the contact surface by total internal reflection; the second angle α2 and the refractive index value n1 are such that the second facet transmits the reflected treatment light to the outside of the plate-shaped light output member by refraction.

2. 2. The human tissue treatment device according to claim 1, wherein the refractive index value n1 is in the range of 1.4 to 1.

7.

3. the first mean propagation direction is different from the second mean propagation direction; 3. The human tissue treatment device according to claim 1, further comprising a light redirecting member disposed between the collimator and the plate-shaped light output member, the light redirecting member redirecting the collimated treatment light from the first mean propagation direction to the second mean propagation direction.

4. the light redirecting member is made of an optically transparent material and has a plate-shaped carrier disposed adjacent to and parallel to an inner surface of the plate-shaped light output member; a first main surface of the plate-shaped carrier facing away from the plate-shaped light output member is flat and extends parallel to the contact surface, and receives the collimated treatment light having the first mean propagation direction, and transmits the received collimated treatment light through the plate-shaped carrier; a second main surface of the plate-shaped carrier facing the plate-shaped light output member is oriented at a third angle α3 with respect to the first main surface, and the second main surface of the plate-shaped carrier comprises an optical structure having one or more third facets for receiving the collimated treatment light transmitted by the first main surface; 4. The human tissue treatment device according to claim 3, wherein the third angle α3, the first mean propagation direction, and a refractive index value n2 of the optically transparent material of the plate-shaped carrier are such that the third facet transmits and redirects the received collimated treatment light from the plate-shaped carrier into the second mean propagation direction by refraction.

5. the optical structure of the second major surface of the light redirecting member includes one or more pairs of a fourth facet and a respective one of the one or more third facets; the fourth facet is oriented with respect to the first major surface of the light redirection member at a fourth angle α; and 5. The human tissue treatment device according to claim 4, wherein α3=α2 and α4=α1.

6. the collimator has first and second end faces and an elongated light guide extending in a direction perpendicular to the contact surface from the first end face to the second end face; the first end surface receives treatment light emitted by the light source; the second end surface transmits the collimated treatment light toward the light redirection member; 6. The human tissue treatment device according to claim 3, wherein the light guide collimates the treatment light received at the first end face by internal reflection of the received treatment light on a peripheral surface of the light guide.

7. the light guide has a central axis extending perpendicular to the contact surface and is circularly symmetrical with respect to the central axis; 7. The human tissue treatment device according to claim 6, wherein the light guide has a cross-sectional area perpendicular to the central axis that gradually increases from the first end face toward the second end face.

8. 8. The human tissue treatment device according to claim 6, wherein the light guide has a large light guide body made of an optically transparent material, and the treatment light received at the first end face is collimated by total reflection of the received treatment light at a peripheral surface of the light guide body.

9. 8. The apparatus for treating human tissue according to claim 7, wherein the first and second facets of the optical structure of said plate-shaped light output member are annular and extend concentrically about a central axis of said light guide.

10. 6. The human tissue treatment device according to claim 4, further comprising a plurality of light sources for emitting the treatment light, and wherein the collimator comprises a separate collimator element for each individual light source for collimating the treatment light emitted by the individual light source.

11. a plurality of light sources that emit the treatment light; the collimator has a separate collimator element for each individual light source that collimates the treatment light emitted by the individual light source; 4. The apparatus for treating human tissue according to claim 3, wherein the light redirecting member comprises a separate light redirecting element for each individual light source disposed between the plate-shaped light output member and a collimator element associated with the individual light source.

12. The apparatus of claim 11 , wherein each light redirecting element comprises a mirror or a prism.

13. a plurality of light sources that emit the treatment light; the collimator has a separate collimator element for each individual light source that collimates the treatment light emitted by the individual light source; 3. The human tissue treatment device of claim 1, wherein each individual light source and each individual collimator element associated with said individual light source are oriented obliquely with respect to a contact surface of said plate-shaped light output member, and wherein said first mean propagation direction and said second mean propagation direction are parallel to each other.

14. the collimator has a plurality of optical fibers that guide the treatment light emitted by the light source to the plate-shaped light output member, the optical fiber has a fiber tip portion oriented such that treatment light emitted by the fiber tip portion has a second mean propagation direction; 3. The human tissue treatment device according to claim 1, wherein the optical fiber receives the treatment light emitted by the light source and maintains the received treatment light at a numerical aperture in the range of 0.01 to 0.

2.

15. the collimator includes a plurality of optical fibers that guide the treatment light emitted by the light source to the light redirection member; the optical fiber has a fiber tip portion oriented perpendicular to the contact surface of the plate-shaped light output member; 6. The human tissue treatment device according to claim 3, wherein the optical fiber receives the treatment light emitted by the light source and maintains the received treatment light at a numerical aperture in the range of 0.01 to 0.

2.

16. 16. A shaving unit for an electric shaver, comprising: a base member; at least one hair-cutting unit supported by the base member; and at least one human tissue treatment device according to any one of claims 1 to 15, wherein a contact surface of a plate-shaped light output member of the human tissue treatment device is positioned relative to the hair-cutting unit so that the contact surface and the hair-cutting unit together come into contact with a user's skin during use of the shaving unit.

17. 17. The shaving unit according to claim 16, further comprising a skin support member having a skin support surface at least partially surrounding the hair-cutting unit, wherein the human tissue treatment device is disposed on the skin support member such that a contact surface of a plate-shaped light output member of the human tissue treatment device forms a part of the skin contact surface of the skin support member.

18. 18. An electric shaver having a main body and a shaving unit according to claim 16 or 17, wherein the main body houses an electric motor, the shaving unit is arranged on the main body, and a hair-cutting unit of the shaving unit is drivable by the electric motor.

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