Skin treatment device

Abstract

The present invention relates to a skin treatment device, which is particularly suitable for household use. The device includes: a housing, a light source accommodated in the housing for releasing light energy pulses, a control system for controlling the release of the light source, and an output window of the housing in the housing for transmitting the light energy pulses emitted by the light source to the outside of the housing onto a skin treatment area. One or more sensors are arranged in the housing adjacent to the housing output window for providing a plurality of sensing areas, wherein the control system is arranged to receive one or more sensor outputs from the one or more sensors and control the operation of the device based on the one or more sensor outputs. A head is arranged to releasably engage with the housing and has a shielding portion and a head window portion, wherein in the engaged configuration, the shielding portion shields a part of the output window to reduce the skin treatment area and exposes one or more of the plurality of sensing areas.

Description

Technical Field

[0001] The present invention relates to a skin treatment device, preferably to a skin treatment device for treating unwanted hair, and preferably includes an intense pulsed light (IPL) device. Background Art

[0002] Skin treatment devices are known in the art for treating, for example, cosmetic applications such as hair removal, minimizing skin blemishes or rejuvenating the skin, and dermatological treatments such as acne or rosacea. The skin is exposed to a dose of radiation from a light source, such as a flash lamp or a laser, where the radiation is directed at the skin and the energy intensity and pulse duration are controlled. In hair removal, the radiation source aims to cause heating of the hair follicle, resulting in death of the hair follicle.

[0003] The safety of skin treatment devices is of utmost importance, especially for devices designed for home use. Therefore, safety features are implemented such that the device will not emit radiation unless it is in contact with the user's skin, to minimize stray radiation from the device during operation. This is typically achieved by providing a plurality of sensors on each side adjacent to the output window in the device head (e.g., above, below, and on both sides of a rectangular output window), where each sensor must detect a surface as a requirement for emitting radiation. If a sensor does not measure a threshold, the control system of the device determines that there is no contact with the skin and prevents activation. This is to prevent activation of the device when there is not good contact with the skin and there is a risk of emitting stray radiation at potentially harmful levels.

[0004] Although the safety features of the device can limit stray radiation, they can affect its usability. For body areas with large flat surfaces, usability is good because the user can easily place the device so that all sensors are in contact with the body, allowing radiation emission and facilitating treatment. However, in more angular or bony areas of the body, it is difficult to orient the head so that all sensors are in contact with the body, thus preventing radiation emission. This leads to user frustration and reduces the efficacy of treatment due to missed difficult-to-treat body areas. Therefore, usability is reduced. Summary of the Invention

[0005] Aspects of the present invention address these problems or at least provide useful alternatives.

[0006] According to a first aspect of the present invention, there is provided a skin treatment device, comprising:

[0007] - a housing;

[0008] - a light source housed in the housing for releasing light energy pulses;

[0009] - A control system for controlling the release of a light source;

[0010] - A housing output window disposed in a housing for transmitting light energy pulses emitted by a light source to the outside of the housing onto a skin treatment area;

[0011] - One or more sensors arranged in the housing adjacent to the housing output window for providing a plurality of sensing areas, wherein the control system is arranged to receive one or more sensor outputs from the one or more sensors and to control the operation of the device based on the one or more sensor outputs;

[0012] - A head arranged to releasably engage with the housing and having a shielding portion and a head window portion, wherein in the engaged configuration, the shielding portion partially shields the housing output window to reduce the skin treatment area and exposes one or more of the plurality of sensing areas.

[0013] Accordingly, the present invention provides a simple and effective solution to the problem of how to reduce stray light radiation when treating a specific body area, such as a bone area, in a cost-effective and simple manner and still maintain usability. Thus, in the engaged configuration, the housing output window is shielded, and thus the skin treatment area is reduced. One or more sensing areas remain exposed, so that the one or more sensors are operable to provide sensor outputs to control the operation of the device. This provides a simple and effective device in which the head does not require the addition of sensors or complex electronics, but means that the device can operate safely while minimizing stray light radiation.

[0014] Controlling the operation of the device may include one or both of the following: determining whether the flash lamp can emit a pulse and determining the characteristics of the pulse (e.g., fluence).

[0015] The head preferably includes a recessed portion arranged to receive a body part of a user. It will be understood that the recessed portion has a skin contact surface. By providing the recessed portion, it is possible to receive difficult body geometries and minimize stray light. The body geometry may be, for example, a bone area, such as the skin on the tibia.

[0016] The recessed portion is preferably concave and is preferably arranged between opposite shoulders. The opposite shoulders are preferably mirror images on both sides of the housing output window. The opposite shoulders preferably extend generally parallel to each other. The shoulders preferably extend generally linearly in a direction parallel to the height of the housing output window.

[0017] The curvature of the concave portion of the concave surface is preferably at least partially defined by a radius of curvature. The radius of curvature reflects the shape of the typical body area to which the head is particularly adapted. The radius of curvature itself can depend on the body area to be treated, and different heads with dimensional parameters can be used for different body areas. As an example, the radius of curvature can have a value defined by the effective width of the shielded housing output window plus a predetermined value, where the predetermined value can be 20 - 60 mm, even more preferably 30 - 50 mm and even more preferably 40 mm. It will be understood that the entirety of the concave portion of the concave surface may not include the radius of curvature, and the radius of curvature can extend from the shoulder towards the housing output window, and the intermediate portion can be more linear, for example, or can include a smaller curvature.

[0018] There are distinct advantages associated with the concave portion, particularly where the radius of curvature of the concave portion is defined by the value of the width of the housing output window plus a predetermined value. By providing such a significant curvature relative to the width of the housing output window, stray light is minimized, and it also means that there is no need to provide any sensors that extend beyond the first and second ends of the housing output window in the width direction.

[0019] The head is advantageously rigid. Thus, under normal operation, the head, particularly the shoulder, does not deform to conform to the user's body part.

[0020] The head window portion preferably includes an opening. Thus, there is no physical window in the opening.

[0021] The housing output window is preferably defined by a width and a height, where the width is greater than the height, and the shield shields the housing output window to reduce the width of the light transmission area in the engaged configuration.

[0022] The head window portion is preferably defined by a width and a height that are respectively aligned with the width and height of the housing output window in the engaged configuration, where the width of the head window portion is less than the height of the head window portion.

[0023] The height of the head window portion is preferably greater than the height of the housing output window.

[0024] The skin treatment device preferably includes a plurality of sensors. Depending on the specific function required, the plurality of sensors can include proximity sensors (e.g., capacitive sensors) and / or optical proximity sensors. However, in any case, advantageously, the sensors can be used to determine the proximity of the surface (skin) to the sensors. If an optical proximity sensor is used, additional functions can be provided, such as the ability to use the sensor output (reflectivity) to determine skin color and thus control the energy output of the light source based on skin color.

[0025] The one or more sensors preferably include at least a first sensor and a second sensor disposed in the housing on diametrically opposite first and second sides of the housing output window, and wherein the first sensor and the second sensor remain exposed in the engaged configuration.

[0026] The first sensor and the second sensor are preferably disposed on first and second sides above and below the housing output window. The first sensor and the second sensor are preferably disposed in a recessed portion of the head, preferably such that at least a portion of the first sensor and the second sensor is located at the deepest part of the recessed portion.

[0027] In an illustrative embodiment, the shape of the housing output window is generally rectangular. A plurality of sensors are preferably disposed in the housing around the peripheral edge of the housing output window.

[0028] The plurality of sensors preferably includes a third sensor and a fourth sensor, which are disposed in the housing on diametrically opposite third and fourth sides of the housing output window.

[0029] The control system is preferably configured to deactivate one or more of these sensors when the head is in the engaged configuration. It will be understood that preferably, when the head is in the engaged configuration, the third sensor and the fourth sensor are deactivated.

[0030] The shielding preferably also shields one or more of the sensors in the engaged configuration. Thus, in the engaged configuration, the third sensor and the fourth sensor are preferably hidden by the shielding.

[0031] The one or more sensors shielded by the shielding are preferably proximity sensors (preferably capacitive sensors), and the shielding is adjacent to the one or more shielded proximity sensors. The shielding can be sufficiently close to the proximity sensors in the engaged configuration such that it is not necessary to deactivate the third sensor and the fourth sensor. Alternatively, the proximity sensors can be functional and thereby output a signal to the control system indicating the proximity of a surface. Advantageously, the control system is arranged to control the operation of the device, for example whether a light source can emit energy pulses in part based on a proximity sensor indicating a predetermined proximity to a surface, which means that in the engaged configuration, the proximity sensors output an affirmative determination of the degree of surface proximity to the control system. The one or more shielded sensors are preferably the third sensor and the fourth sensor.

[0032] The head preferably does not include any sensors. This means that the head is easy to manufacture as no complex electronics are required. This also means increased robustness of the relatively small attachment.

[0033] The head is preferably magnetically coupled to the housing.

[0034] The device preferably includes engagement sensor means for determining whether the head is in an engaged configuration. The control system can be operable to modify the operating parameters of the device based on the output of the engagement sensor means. The operating parameters can be one or more of the following: a) one or more of these sensors to be deactivated when the head is in the engaged configuration; b) the frequency of light energy pulse emission; c) the energy value of the emitted light energy pulses. The engagement sensor means can include one or more Hall effect sensors.

[0035] The device is preferably of the intense pulsed light (IPL) type.

[0036] According to another aspect of the present invention, there is provided a skin treatment device comprising:

[0037] - a housing;

[0038] - a light source housed within the housing for emitting light energy pulses;

[0039] - a control system for controlling the emission of the light source;

[0040] - the housing has a head which includes a recessed area defined between opposing shoulders for receiving a user body part, and in the recessed area there is an output window for transmitting the light energy pulses emitted by the light source to the outside of the housing onto a skin treatment area, the output window having a width and a height, the width being defined by a first end and a second end and extending in a direction between the opposing shoulders;

[0041] - one or more sensors arranged in the housing for sensing a user body part on opposite sides of the output window, wherein the one or more sensors do not extend in the width direction beyond the first end and the second end of the output window;

[0042] - the control system is arranged to receive sensor output from the one or more sensors and to control the operation of the device based on the sensor output.

[0043] Controlling the operation of the device can include one or both of the following: determining whether the flash lamp can emit a pulse and determining the characteristics of the pulse (e.g., fluence).

[0044] The head is preferably integral with the housing. This means that the head is preferably not separable from the housing.

[0045] The shape of the head is preferably the same as the shape described in relation to the first aspect of the present invention. Preferably, the recessed area is concave, and the curvature of the concave recessed area is preferably at least partially defined by a radius of curvature. It should be understood that the radius of curvature requires that in the case of a cylinder being located in the recessed area, there are multiple contact points between the contact surface of the cylinder and the recessed area.

[0046] The radius of curvature may include a value defined by the width of the output window plus a predetermined value, where the predetermined value may be 40 mm. Thus, in an illustrative embodiment, the width of the output window may be 10 mm and the radius of curvature may be 50 mm.

[0047] The one or more sensors are preferably arranged adjacent to the output window. Preferably, the first sensor and the second sensor are arranged in the housing. The first sensor and the second sensor are preferably aligned on opposite sides of the output window. The first sensor and the second sensor are preferably provided at the lowermost part of the recessed area. It will be understood that the recessed area includes the user contact surface.

[0048] The head is preferably rigid. This means that during normal operation, the head does not deflect. Description of the Drawings

[0049] Aspects of the present invention will now be described by way of example only with reference to the drawings, in which:

[0050] Figure 1a-1c A schematic view of an illustrative embodiment of the present invention is shown, in which the head is not in place;

[0051] Figure 2a-2c Schematic illustrative embodiments of the present invention are shown in perspective, plan and side views respectively, in which the head is fixed to the front end of the housing;

[0052] Figure 3 Is a schematic view of an exemplary embodiment of the present invention, which shows an exemplary curvature of the head;

[0053] Figure 4 Is a rear view of the head according to an illustrative embodiment of the present invention;

[0054] Figure 5a-5d Are schematic upper perspective, front, plan and bottom perspective views of an illustrative embodiment of the present invention. Detailed Description

[0055] Refer to Figure 1a-1c, shows a skin treatment device that can be used to treat skin diseases and conditions and is even more advantageously suitable for cosmetic purposes such as hair removal. The device includes a housing 50 and a light source 22 housed within the housing, such as a discharge lamp or a flash lamp. The flash lamp is arranged to generate high-intensity light radiation pulses. The housing 50 includes a handle 52, which means that the housing 50 can be manipulated to be properly placed on the user, and since the device is handheld, relatively small, and portable, it is particularly suitable for the home market. The housing 50 includes a skin contact element 54 that is arranged to be adjacent to or preferably located on the user's skin when no head is provided during use. The skin contact element 54 includes a light output window 56 or a transmission window or an output aperture through which the high-intensity light radiation pulses pass, typically 30 mm in width and 10 mm in height, where an optical waveguide 55 is defined between the light output aperture / transmission window / output window 56 and the light-emitting element 22. The cross-sectional area of the light output aperture / transmission window / output window 56 is actually the treatment area. The provision of the optical waveguide 55, which can be referred to as an optical duct, is to guide the light out of the light output aperture / transmission window / output window 56. Preferably includes a reflector (not shown) that defines at least a portion of the wall of the optical waveguide 55 to assist in reflecting the light through the light output aperture / transmission window / output window 56. Thus, the light-emitting element 22 is recessed relative to the light output aperture / transmission window / output window 56. The effect of providing the optical waveguide 55 is to improve safety by reducing the divergence of the light emitted from the device towards the skin.

[0056] The skin contact element 54 also includes a first sensor, a second sensor, a third sensor, and a fourth sensor 58a, 58b, 58c, 58d, which will be further described below to provide associated sensing areas. An actuator 62, such as a button, is provided for the user to release energy from a charge storage device, such as a capacitor 20, thereby causing a light radiation pulse to be emitted from the flash lamp 22.

[0057] Referring to Figure 1b , a cross-section of the housing 50 is again shown, which shows the handle 52, the light output aperture 56, and the sensors 58c, 58d. A fan 66 for cooling the control circuit 28 on the main printed circuit board is also shown. Figure 1b The lamp 22 fixed in the housing 50 is also shown. A filter 68 is provided to filter out the ultraviolet light transmitted from the lamp 22 to the skin. The treatment light pulse generated by the lamp 22 passes through the filter, through the light output window 56, and reaches the user's skin.

[0058] Particularly referring to Figure 1c , a cross-sectional view is taken along an axis that is substantially perpendicular to Figure 1b the perspective. Figure 1cShown therein are a charger circuit 26, a control circuit 28 mounted on a printed circuit board, a lamp 22, a filter 68, and a light output window 56. Also shown is a reflector 70 for reflecting light radiation pulses, and an energy storage device including a capacitor 20 is housed within a handle portion 52 of a housing 50. An opening 72 for power input is provided on the handle.

[0059] The device operates effectively by the user providing an input to an actuator 62 and then determining whether a threshold response is received from all sensors 58, and assuming that each sensor provides a threshold response, the capacitor 20 discharges through the flash lamp 22.

[0060] Sensors can take different forms depending on the device using them. For example, these sensors can include only a plurality of proximity sensors in the form of capacitive proximity / contact sensors, each having a sensing area, where the control system requires a predetermined capacitance to be measured from each sensing area to indicate contact with the user's skin. Assuming the threshold is measured, the control system activates the flash lamp to emit light energy pulses. However, one or more alternative or additional skin parameters can be sensed. For example, one or more sensors can include optical sensors commonly referred to as skin color sensors or sometimes also as proximity sensors, and can replace one or more other sensor types, such as capacitive sensors, either alternately or in series. In the presented embodiment, there are three capacitive proximity sensors and one optical proximity sensor (or "skin color sensor" 58a). The skin color sensor includes a transmitter arranged to emit sensing radiation through a sensor window onto the skin to be treated. The sensor 58a also includes a receiver arranged to receive the radiation reflected from the skin surface, such as a photodiode. The intensity of the received radiation is found to represent the skin tone, for example, light skin tones will reflect more than dark skin tones. The intensity of the received radiation can be processed by the control circuit 28 using a processor provided thereby, and compared with a set of calibrated intensity measurements to determine the sensed skin color, which is then stored in the memory of the control circuit. The energy of the treatment light pulses output to the skin can then be controlled and thus depends on the sensed skin color, thereby ensuring optimal treatment for the specific skin color to be treated.

[0061] It will be understood that a single sensor having a plurality of sensing areas adjacent to the output window 56 can be utilized. The single sensor can, for example, extend around the entire output window 56, and the sensing areas are above, below, and on both sides of the output window 56. However, it is preferred to provide a plurality of sensors in the vicinity of the output window 56.

[0062] As described above, in the illustrative embodiments, a plurality of individual sensors are disposed around the output window 56. Typically, four sensors providing four separate sensing regions are provided on opposite sides of the output window 56: a first sensor 58a above the output window 56, a second sensor 58b below the output window 56, a third sensor 58c and a fourth sensor 58d on opposite sides of the output window 56. It will be understood that in alternative embodiments, there may be a different number of sensors. For example, a single sensor may include multiple sensing regions.

[0063] Now referring Figure 2a-2c , to the schematic illustrative embodiments shown respectively in perspective, plan and side views of the present invention, wherein the head 100 is fixed to the front end of the housing 50. The head 100 is disposed at the front end of the housing 50 and may be fixed relative to the housing by one or more magnets, as Figure 4 shown.

[0064] The head 100 includes a window portion 102 and a shielding portion 104. Through the window portion 102, the output window 56 and the first sensor 58a and the second sensor 58b remain exposed, while the third sensor 58c and the fourth sensor 58d are shielded. The effective width of the output window 56 of the housing 50 is reduced and, in one illustration, may be reduced from a width of 30 mm to 10 mm. The height remains the same such that the first sensor 58a and the second sensor 58b remain exposed.

[0065] The head 100 further includes a recess 106 defined between opposing shoulders 108, and the shape of the recess is concave. This shape effectively receives small and / or highly curved user body parts (e.g., tibia, arm, finger). The curvature of the concave recess 106 is defined by a radius of curvature schematically shown in Figure 3 , where a cylinder with a radius of 50 mm is shown, and the width of the head window portion 102 thereof is 10 mm. This curvature causes a cylinder 110 with a radius of 50 mm to fall at least in part within the curvature of the radius of the head in the portion extending from the shoulders 108 towards the window portion 102. In the case where the width of the head window portion 102 is increased to 20 mm, the radius of curvature of the concave recess will be 60 mm. This determination is made to minimize stray radiation escaping from the head window portion 102.

[0066] The opposing shoulders 108 are mirror images on opposite sides of the recess 106 and generally extend longitudinally and generally parallel to the height of the output window 56. It should be understood that for the device to operate, the first sensor 58a and the second sensor 58b must receive input signals indicating proximity to the user's skin and, together with the recess 106, minimize stray light.

[0067] An optional feature is that when the head 100 is engaged with the housing 50, the control system deactivates the third sensor 58c and the fourth sensor 58d. To do this, the control system must receive an input indicating that the head 100 has been engaged. Referring to Figure 4 , the rear of the head 100 is shown. There is a pair of magnets 110 in the head 100 for achieving magnetic coupling with the housing 50. The housing 50 may include corresponding metal elements appropriately aligned with the magnets 110 to ensure a sufficiently firm coupling such that the head does not decouple during normal use. A engagement sensor device is also provided, such as one or more Hall effect sensors (not shown), which is capable of detecting the presence of the head 100 in the engaged configuration via the magnetic field from the magnets. The Hall effect sensor is then able to provide an output to the control system to indicate engagement with the head 100 and deactivate the third sensor 58c and the fourth sensor 58d, such that only threshold signals from the first sensor 58a and the second sensor 58b are required to permit the emission of a light energy dose.

[0068] The engagement sensor device may have other functions in identifying the particular head that is engaged. Multiple head sizes may be provided to treat different body regions, each body region having a different user contact surface configuration, such as a different radius of curvature. The engagement sensor device may be arranged to determine which head is engaged (e.g., by a plurality of Hall effect sensors and different magnet configurations for each head size), and control the output parameters accordingly based on this information.

[0069] In an embodiment of the invention, a single sensor may be provided, typically but not necessarily, extending around the entire periphery of the output window 56, where in the case of the head 100 being engaged, only certain sensing regions remain exposed. For example, the sensing regions above and below the output window may remain exposed, and the sensing regions on either side of the output window may be shielded. In this embodiment, when the head is attached, the threshold level of the sensor output may be modified to a lower value to compensate for the fact that the sensing regions on either side of the output window are shielded and unable to determine the proximity of the skin. This may be done automatically by the control system upon determining that the head is in the engaged position by means of the output from the engagement sensor device.

[0070] In Figure 4 the provision of the reflector shields 112 is further shown. These reflector shields 112 provide a shielding portion 104 of the head 100 and thus reduce the skin transmission window of the housing and thus reduce the skin treatment area. These shields 112 are reflective and insulating such that the head 100 does not absorb a large amount of energy and does not overheat.

[0071] The provision of the engagement sensor device can have additional beneficial uses. For example, the output from the engagement sensor device can enable the control system to modify the operating parameters of the device, where the operating parameter can be the pulse emission rate from the light source, the energy output from each pulse, and / or the operating state of the one or more sensors described above. The pulse emission rate can be modified to reduce the likelihood of overheating of the head, and thus, when the head 100 is in the engaged configuration, the control system can automatically reduce the rate. Additionally, the energy output from the light source can be modified to maintain the same flux (energy per unit area) on the skin as if the head 100 were not in place.

[0072] Now refer to Figure 5a-5d , which is a schematic perspective view of an embodiment according to a second aspect of the present invention, wherein the housing 50 includes an integral head, and the head has the same geometry of the recess 106 as in the first embodiment described above, providing a recessed area for receiving a user's body part. Figure 5a is a schematic upper perspective view of such an illustrative embodiment of the present invention, Figure 5b is a front view, Figure 5c is a plan view, Figure 5d is a bottom perspective view.

[0073] In this embodiment, the head 110 is non-removable, and the area of the light output window 56 and thus the treatment area remains unchanged. Components similar to those in the first embodiment have been denoted with the same reference numerals. The function of the device can be the same as that of the first embodiment described with respect to FIG. 1, except for the head 110.

[0074] The head 110 includes a recess 106 defined between opposing shoulders 108, and the shape of the recess is concave. This shape includes a skin contact portion 109 in the form of a rim. Thus, the recess 106 effectively receives small and / or highly curved user body parts (e.g., shin, arm, finger). The curvature of the concave skin contact portion 109 in the recess 106 is at least partially defined by the radius of curvature, and this can be shown in the same manner as Figure 3 shown. In the Figure 5a-5d illustrative embodiment, the width of the output window 56 is 30 mm, and thus the radius of curvature is advantageously 70 mm. It should be understood that, as clearly shown in the drawings, the radius of curvature does not extend the entire distance between the opposing shoulders 108. Instead, the radius of curvature extends from the shoulders 108 inwardly towards an intermediate position 112 of the skin contact portion 109, where the curvature decreases towards the intermediate position 112.

[0075] The opposing shoulders 108 are mirror images on opposite sides of the recess 106 and extend generally longitudinally and generally parallel to the height of the output window 56. It should be understood that for the device to operate, the first sensor 58a and the second sensor 58b must receive input signals indicative of proximity to the user's skin and, together with the recess 106, minimize stray light. The first sensor 58a and the second sensor 58b are provided at intermediate positions 112 of the skin contact portions 109 on opposite sides of the output window 56. These sensors do not extend in the width direction beyond the first and second ends of the output window 56. In fact, the output window 56 extends adjacent to the shoulders 108.

[0076] As Figure 5a-5d shown, due to the head shape and the sensor arrangement for body curved regions, the functionality of the device is significantly improved while ensuring safety by minimizing the emission of stray light energy. Due to the recessed region of the head, sensors do not need to be provided on the sides of the output window, and by not providing such sensors, usability is improved because only sensors above and below the output window are needed to determine the presence of skin for the device to emit energy pulses, but safety is not compromised because the curvature ensures that stray light is minimized. Additionally, since fewer sensors or sensing areas are required, the complexity of the device is reduced.

[0077] Aspects of the invention are described by way of example only, and those skilled in the art will understand that modifications and variations can be made without departing from the scope of protection provided by the appended claims.

Claims

1. A skin treatment device, characterized in that: Comprising: - A housing; - A light source housed within the housing for emitting light energy pulses; - A control system for controlling the emission of the light source; - A housing output window provided in the housing for transmitting the light energy pulses emitted by the light source to the outside of the housing onto a skin treatment area; - One or more proximity sensors for determining the proximity of the skin, the one or more proximity sensors being arranged in the housing adjacent to the housing output window for providing a plurality of sensing areas, wherein the control system is arranged to receive one or more sensor outputs from the one or more proximity sensors and control the operation of the device based on the one or more sensor outputs; - A head, the head being arranged to releasably engage with the housing and having a shielding portion and a head window portion, the head not including the proximity sensors, wherein in the engaged configuration, the shielding portion shields part of the output window to reduce the skin treatment area, shields one or more of the sensing areas, and exposes one or more of the plurality of sensing areas.

2. The skin treatment device according to claim 1, characterized in that: The head includes a recessed portion arranged to receive a body part of the user.

3. The skin treatment device according to claim 2, characterized in that: The recessed portion is concave.

4. The skin treatment device according to claim 2, characterized in that: The recessed portion is arranged between opposite shoulders.

5. The skin treatment device according to claim 3, characterized in that: The curvature of the concave portion of the concave surface is at least partially defined by a radius of curvature.

6. The skin treatment device according to claim 5, characterized in that: The radius of curvature has a value defined by the width of the shielded housing output window plus a predetermined value, wherein the predetermined value is 20 - 60 mm.

7. The skin treatment device according to claim 6, characterized in that: The predetermined value is 30 - 50 mm.

8. The skin treatment device according to claim 7, characterized in that: The predetermined value is 40 mm.

9. The skin treatment device according to claim 1, characterized in that: The head is rigid.

10. The skin treatment device according to claim 1, characterized in that: The head window portion includes an opening.

11. The skin treatment device according to claim 1, characterized in that: The housing output window is defined by a width and a height, wherein the width is greater than the height, and wherein the shielding portion shields the housing output window to reduce the width of the light transmission area in the engaged configuration.

12. The skin treatment device according to claim 11, characterized in that: The head window portion is defined by a width and a height that are respectively aligned with the width and height of the housing output window in the engaged configuration, wherein the width of the head window portion is less than the height of the head window portion.

13. The skin treatment device according to claim 11, characterized in that: The height of the head window portion is greater than the height of the housing output window.

14. The skin treatment device according to claim 1, characterized in that: The one or more proximity sensors include at least a first sensor and a second sensor, the first sensor and the second sensor being arranged in the housing on diametrically opposite first and second sides of the housing output window, and wherein the first sensor and the second sensor remain exposed in the engaged configuration.

15. The skin treatment device according to claim 14, characterized in that: The plurality of proximity sensors includes a third sensor and a fourth sensor provided in the housing on diametrically opposite third and fourth sides of the housing output window.

16. The skin treatment device according to claim 1, characterized in that: The control system is configured to deactivate one or more of the proximity sensors when the head is in the engaged configuration.

17. The skin treatment device according to claim 1, wherein: The shielding portion also shields one or more of the proximity sensors in the engaged configuration.

18. The skin treatment device according to claim 1, wherein: The head does not include any sensors.

19. The skin treatment device according to claim 1, wherein: The head is magnetically coupled to the housing.

20. The skin treatment device according to claim 1, wherein: It further includes a engagement sensor device for determining whether the head is in the engaged configuration, and wherein the control system is operable to modify the operating parameters of the device according to the output of the engagement sensor device.

21. The skin treatment device according to claim 1, wherein: The one or more proximity sensors include a capacitive proximity sensor and / or an optical proximity sensor.

22. The skin treatment device according to claim 1, wherein: The device is an intense pulsed light (IPL) device.

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