Patent Description:
Many types of personal care device exist that can be used to perform an energy-based treatment on a subject, for example on the hair and/or skin of the subject.

Light-based hair removal is a treatment used to inhibit the growth of hair by exposing the skin to bright flashes or pulses of light, which can be referred to as IPL (Intense Pulsed Light) where the light pulse is generated by a lamp or light bulb. Alternatively the flash or pulse can be generated using a laser or one or more light emitting diodes (LEDs). The light penetrates the skin and is absorbed - among other places - in the root of the hair. The temperature of the root of the hair will rise and subsequently the temperature of the surrounding tissue will also rise. The growth of the hair is inhibited if the temperature rise is sufficient. This process is known as photothermolysis.

A personal care device may include one or more sensors for monitoring one or more parameters before or during a personal care operation. For example, contact with skin is required for successful photoepilation treatment and to prevent a light pulse being directed into other body parts such as eyes, which can result in injury. Therefore the personal care device may include a skin contact sensor for measuring or detecting contact with the skin. Another type of sensor used in personal care devices is a skin tone sensor that measures the tone of the skin to which an energy-based treatment (e.g. photoepilation) is to be applied.

Personal care devices performing an energy-based treatment may heat up during use, especially during prolonged periods of use. Increasingly stringent safety standards (e.g. IEC <NUM>) describe maximum temperature limits for parts of personal care devices having contact with the body of a subject.

To ensure compliance with such safety standards, a temperature sensor is often provided on a part of a personal care device having contact with the body of a subject. If the temperature of a part of the device rises above a temperature limit, the device may 'time-out' to allow cooling.

<CIT> (<CIT>) discloses a device which comprises a housing <NUM>, the housing <NUM> comprising a flash lamp <NUM> and an air cavity <NUM>. The air cavity has a primary opening which is placed against the body and directs the lamp energy to the hair. In figure 5A, the housing <NUM> further includes an opening which allows the air to be pumped out of the cavity via an air pump.

Another personal care device with a cooling arrangement is known from <CIT>.

It is desirable that external components of a personal care device remain within temperature ranges that are comfortable for users. The present inventors have determined that the air contained within a personal care device's treatment cavity may be incidentally heated by the treatment energy as it passes through the treatment cavity, causing a rise in temperature and pressure of this confined air. The heated air may leave from the treatment cavity via the opening in contact with the body of the subject, the heated air thus passing across the body of the subject and heating up external surfaces of the device. This may negatively affect user experience. Improved cooling arrangements may thus be desirable. Further, it would be advantageous to perform cooling whilst the device is performing the energy-based treatment.

According to a first specific aspect, there is provided a personal care device configured to perform an energy-based treatment on a portion of a body of a subject, the personal care device comprising: a main body portion including an energy source; and a cavity having a primary opening, the cavity being configured to transmit treatment energy from the energy source to the primary opening, wherein the primary opening is configured to be placed against the body during use of the personal care device to define the portion of the body being treated by means of the treatment energy, and to define a volume of air within the cavity, wherein the cavity comprises a secondary opening arranged at a distance from the primary opening and at a distance from the body when the primary opening is placed against the body and configured to permit a flow of air via the secondary opening and, thereby, a flow of air out of the cavity whilst treatment energy is transmitted from the energy source to the primary opening, and wherein the personal care device comprises a detachable portion configured to be detachable from the main body portion of the personal care device, the detachable portion comprising the cavity, the primary opening and the secondary opening.

The secondary opening may be configured to permit a flow of air via the secondary opening into the cavity and via the primary opening out of the cavity. The secondary opening may be configured such that, during use, the cavity is in fluidic communication with an internal air flow within the personal care device via the secondary opening. The secondary opening may be configured to be permanently open. The secondary opening may be provided along an axis tilting away from a direction of propagation of treatment energy generated by the energy source. The secondary opening may be provided along an axis tilting away from a direction of propagation of treatment energy incident upon the secondary opening during use. The secondary opening may be provided along an axis passing through the primary opening of the cavity. The secondary opening may be provided along an axis configured to restrict a loss of treatment energy, generated by the energy source, from the cavity via the secondary opening.

The cavity may comprise at least one reflector wall configured to reflect and thereby direct treatment energy from the energy source towards the primary opening of the cavity. The secondary opening may be provided in the reflector wall. The cavity may comprise a plurality of secondary openings.

The secondary opening may comprise a leading edge and a trailing edge, the leading edge being configured to extend beyond the trailing edge with respect to a direction of propagation of treatment energy incident upon the secondary opening, the secondary opening thereby being configured to restrict a loss of treatment energy from the cavity via the secondary opening.

The personal care device may comprise an auxiliary reflector provided externally of the cavity and in alignment with the secondary opening, the auxiliary reflector being configured to reflect treatment energy propagating from the cavity into the secondary opening back into the cavity via the secondary opening. The personal care device may comprise a reflective surface provided within the secondary opening, the reflective surface being configured to restrict a loss of treatment energy from the cavity via the secondary opening.

The personal care device may further comprise a supporting surface surrounding the primary opening and arranged to contact and support the portion of the body during use. The supporting surface may comprise at least one groove configured to be in fluidic communication with the cavity and with ambient air when the supporting surface is in contact with the portion of the body. At least one protrusion may be provided on the supporting surface.

The personal care device may be a skin care device. The energy source may comprise a light source. The treatment energy may comprise intense pulsed light.

With reference to <FIG>, a personal care device <NUM> is configured to perform an energy-based treatment on a portion of a body of a subject. In particular, the personal care device <NUM> depicted in <FIG> is a skin care device configured to perform an intense pulsed light (IPL)-based treatment on a portion of a body of a subject, for the purposes of hair removal and/or hair growth inhibition, i.e. a photoepilator configured to perform photoepilation. However, it should be understood that the personal care device <NUM> depicted in <FIG> is merely presented as an example of a personal care device <NUM> to which the present invention may be applied. For example, the personal care device <NUM> may be configured to perform an alternative energy-based treatment, relating to heat, and/or light and/or to apply another form of treatment energy to the body, such as a dermatological treatment, including hair growth reduction, treating acne, a phototherapy treatment, skin rejuvenation, skin tightening, port-wine stain treatment; and pain relief.

As described herein, the term 'user' refers to the person controlling the device, and the term 'subject' refers to the recipient of the treatment (e.g. a person or an animal). The user of the personal care device <NUM> may be the subject, or alternatively the personal care device <NUM> may be used by a user on a subject wherein the user and the subject are not the same.

The personal care device <NUM> comprises a main body portion <NUM> having a handle <NUM> and a user control <NUM>. The handle <NUM> is shaped and sized such that the personal care device <NUM> can be grasped in one or both hands of a user. The user control <NUM> can be operated by the user (e.g. a user's digit from a hand grasping the handle <NUM>) to activate the personal care device <NUM> so that the energy-based treatment is performed on the body of the subject. The user control <NUM> may be in the form of a switch, a button, a touch pad, etc..

The personal care device <NUM> comprises a detachable portion <NUM> configured to be detachable from, and re-attachable to, the main body portion <NUM>. As will be described below, the detachable portion <NUM> is configured to interact and communicate with features of the main body portion <NUM>.

For ease of reference, components of the personal care device <NUM> may be described in relation to the orientation shown in <FIG> - the end of the personal care device <NUM>, including the detachable portion <NUM>, nearest the left hand side of the page, will be described as the 'front'; the end nearest the right hand side of the page will be described as the 'back'; the part of the device <NUM> nearest the top of the page as the 'top'; the end nearest the bottom of the page as the 'bottom'; the side of the device <NUM> into the page as 'left'; and the side of the device coming out of the page as 'right'. The top, bottom, left and right directions may be indicated in reference numerals with the letters 'T', 'B', 'L' and 'R' respectively.

<FIG> shows a front view of the detachable portion <NUM> of the personal care device <NUM>. A schematic representation of a vertical section through the detachable portion <NUM> along the line III-III is shown in <FIG>.

With reference to <FIG>, <FIG> and <FIG>, the detachable portion <NUM> comprises a housing <NUM> having a face <NUM> which is configured to be placed, in use, against a body of a subject. The face <NUM> comprises a skin tone sensor <NUM> which may be used to determine the skin tone of the portion of the body on which the personal care device <NUM> is used, such that a suitable dose of energy-based treatment may be administered to the portion of the body of the subject. The face <NUM> additionally comprises two skin contact sensors <NUM>, which may be provided on or in the face <NUM>, and configured to determine whether the face <NUM> is in contact with the body of the subject. The skin contact sensors <NUM> may measure a parameter that is indicative of whether the face <NUM> is in contact with skin, and generate respective measurement signals (referred to as 'skin contact measurement signals'). Typically a skin contact sensor <NUM> is used in a personal care device <NUM>, particularly a photoepilator, to make sure that the personal care device <NUM> is correctly in contact with skin before a light pulse is generated to avoid the light pulse being directed into the eyes of the user or subject.

The parameter can be capacitance, and so the skin contact sensors <NUM> can measure capacitance via a respective pair of electrical contacts or electrodes on the surface of the face <NUM>, with the measured capacitance being indicative of whether there is skin contact. Alternatively, the parameter can be an intensity or level of light, and so the skin contact sensors <NUM> can be light sensors that measure an intensity or level of light incident on the light sensor, with the measured intensity or level being indicative of whether there is skin contact (e.g. less/no light could indicate skin contact as the skin obscures the light sensors <NUM>, and vice versa). In other alternatives, the parameter can be a measure of contact pressure, and so the skin contact sensors <NUM> can measure contact pressure via respective pressure sensors or mechanical switches, with the measured contact pressure being indicative of whether there is skin contact.

The detachable portion <NUM> comprises an engagement portion <NUM>, which may, for example, comprise barbed flanges or tabs, configured to engage a corresponding portion (not shown) of the main body portion <NUM>. Detachment of the detachable portion <NUM> from the main body portion <NUM> may require a threshold force in order to disengage the corresponding engagement portions <NUM>.

The face <NUM> comprises a primary opening <NUM> formed where a cavity <NUM> of the detachable portion <NUM> intersects the face <NUM>. A supporting surface <NUM> is provided about the primary opening <NUM>, the supporting surface <NUM> being configured, in use, to be placed against the body of the subject being treated.

The cavity <NUM> is configured to transmit energy from an energy source <NUM> (<FIG>) to the primary opening <NUM>. For example, an energy source <NUM> may be provided outside of the cavity <NUM> and treatment energy may be transmitted into the cavity, e.g., by an energy window <NUM> (<FIG>). A reflector (not shown) may be provided about the energy source <NUM> to direct treatment energy into the cavity <NUM>. The cavity <NUM> may be configured to transmit treatment energy from an internal end <NUM> of the cavity <NUM> towards the primary opening <NUM>.

Additionally or alternatively, an energy source <NUM> may be provided within the cavity <NUM>, and the cavity <NUM> may be configured to transmit treatment energy from an energy source <NUM> disposed part way along, i.e. within, the cavity <NUM>, towards the primary opening <NUM>.

The cavity <NUM> comprises at least one reflector wall 36T, 36B, <NUM>, 36R (collectively <NUM>) configured to reflect, and thereby direct, treatment energy towards the primary opening <NUM>. The at least one reflector wall <NUM> is opaque to the treatment energy emitted by the energy source <NUM>. In the example shown in <FIG> and <FIG>, the top, bottom, left and right reflector walls 36T, 36B, <NUM>, 36R each comprise a respective reflective surface 37T, 37B, <NUM>, 37R (collectively <NUM>) within the cavity <NUM>. It will be understood by the skilled person that alternative reflector wall <NUM> configurations may be suitable, for example a reflector wall of circular cross section rather than rectangular. Additionally or alternatively, not every reflector wall <NUM> may require or comprise a reflective surface <NUM>.

A secondary opening 38T, 38B, <NUM>, 38R (collectively <NUM>) is provided in at least one of the reflectors walls <NUM>. In the example shown in <FIG> and <FIG>, a respective secondary opening 38T, 38B, <NUM>, 38R is provided in each of the top, bottom, left and right reflector walls 36T, 36B, <NUM>, 36R. The secondary opening <NUM> is arranged at a distance from the primary opening <NUM>, such that in use, the secondary opening <NUM> is provided at a distance from the body of the subject. The secondary opening <NUM> is configured to permit a flow of air via the secondary opening <NUM> and, thereby, a flow of air out of the cavity <NUM> whilst treatment energy is transmitted from the energy source <NUM> to the primary opening <NUM>. The secondary opening <NUM> may be configured to be permanently open. For example, the secondary opening <NUM> may be configured to permit a flow of air, via the secondary opening <NUM>, into the cavity <NUM> and, via the primary opening <NUM>, out of the cavity <NUM>, whilst treatment energy is transmitted from the energy source <NUM> to the primary opening <NUM>. The secondary opening <NUM> may be configured to permit a flow of air into and/or out of the cavity whilst treatment energy is not being transmitted from the energy source <NUM> to the primary opening <NUM> (e.g. immediately after the transmission of treatment energy).

Each secondary opening <NUM> may comprise a cross section of any suitable shape, including but not limited to a circle, an ellipse, a square, a rectangle, or an annulus. In the example shown in <FIG> and <FIG>, each secondary opening <NUM> has a circular cross section.

The secondary opening <NUM> may be configured to restrict a loss of treatment energy from the cavity <NUM> via the secondary opening <NUM> (e.g. for a photoepilator, to minimise a loss in optical efficiency). <FIG> shows a schematic section through a cavity <NUM> comprising a secondary opening <NUM> configured to restrict a loss of treatment energy via secondary opening <NUM>. The secondary opening <NUM> shown in <FIG> is provided along an axis <NUM> which is offset or tilted away from a direction of propagation <NUM> of treatment energy, and offset or tilted away from a direction <NUM> of treatment energy incident upon the secondary opening 38B. Additionally or alternatively, the secondary opening <NUM> may be provided along an axis <NUM> tilting away from a longitudinal axis of the cavity <NUM>; and/or provided along an axis <NUM> passing through the primary opening <NUM> (e.g. a centre point of the primary opening <NUM>).

The illustrated axis <NUM> of the secondary opening <NUM> gives rise, with respect to a direction of propagation <NUM> of treatment energy being incident upon the secondary opening <NUM>, to a leading edge <NUM> of the reflector wall <NUM> and a trailing edge 41of the reflector wall <NUM>. The leading edge <NUM> may overlap and/or extend beyond the trailing edge <NUM> with respect to a direction of propagation <NUM> of treatment energy within the cavity <NUM>. The leading edge <NUM> may be at an angle β to the reflective surface 37B of the reflector wall 36B. The trailing edge <NUM> may be at an angle α to an external surface of the reflector wall 36B. Angle α may be less than or equal to angle β. Angle α may be less than <NUM>°, preferably less than <NUM>°. The difference between angle α and angle β may be less than <NUM>°.

Additionally or alternatively, the secondary opening <NUM> may be provided along an axis <NUM> which is perpendicular to a direction of propagation <NUM> of treatment energy towards the primary opening <NUM>. The secondary opening <NUM> may be provided along an axis <NUM> which is perpendicular to a longitudinal axis of the cavity <NUM>.

The secondary opening <NUM> may comprise a reflective surface <NUM> provided on an interior surface of the secondary opening <NUM>, the reflective surface <NUM> being configured to restrict a loss of treatment energy from the cavity <NUM> via the secondary opening <NUM>.

The secondary opening <NUM> may be configured to restrict a loss of treatment energy from the cavity <NUM> by limiting the cross sectional area (or, if a plurality of secondary openings <NUM>, the total cross sectional area of the secondary openings <NUM>). For example, if the treatment energy comprises light, then a reduced diameter of the secondary opening <NUM> will reduce optical losses from the cavity.

It would be advantageous if the cross sectional area of the secondary opening <NUM> (or, if a plurality of secondary openings <NUM>, the total cross sectional area of the secondary openings <NUM>) were large enough to allow sufficient air flow, and thus sufficient cooling, of the cavity <NUM> (e.g. sufficient cooling for the cavity <NUM> to remain below certain threshold temperatures). Preferably, the total area of the secondary openings <NUM> is more than <NUM><NUM>, more preferably more than <NUM><NUM>, most preferably <NUM><NUM>.

It would be advantageous if the hydraulic diameter of the secondary opening <NUM> (or, if a plurality of secondary openings <NUM>, the total hydraulic diameter of the secondary openings <NUM>) were small enough to reduce drag of air passing through the secondary openings <NUM> to negligible levels. The hydraulic diameter of each secondary opening <NUM> is preferably less than <NUM>, more preferably less than <NUM>. Accordingly, multiple secondary openings <NUM> may be required to meet both the area requirement and hydraulic diameter requirement.

The secondary openings <NUM> may be evenly and/or uniformly distributed throughout the reflector walls <NUM>. In the example shown in <FIG> and <FIG>, one secondary opening <NUM> is provided in the centre of each reflector wall <NUM>. In alternative arrangements (not shown), multiple secondary openings <NUM> may be provided in each reflector wall <NUM> and/or at least one reflector wall <NUM> may comprise no secondary openings <NUM>.

The skilled person will be able to determine the appropriate number of secondary openings <NUM> according to the parameters of the personal care device <NUM>, including the rate of heat generation, and a balancing of the competing factors of cross sectional area, hydraulic diameter and energy loss from the cavity <NUM>.

In one example not shown, the reflector wall <NUM> may comprise a plurality of louvres or slats arranged in parallel, having secondary openings <NUM> in the form of slits provided therebetween. A reflective surface <NUM> provided on each louvre may direct treatment energy towards the primary opening <NUM>, whilst the slits therebetween permit a flow of air through the secondary openings <NUM>. A leading edge <NUM> and trailing edge <NUM> configuration may then be achieved in a similar manner to <FIG>.

<FIG> shows a schematic vertical section through the personal care device <NUM> when the detachable portion <NUM> is attached to the main body portion <NUM> by means of the engagement portion <NUM> and corresponding portion (not shown) of the main body portion <NUM>. For simplicity, the handle <NUM> and user control <NUM> of the main body portion <NUM> have been omitted from <FIG>.

The main body portion <NUM> comprises a housing <NUM> having an inlet vent <NUM> which may be configured to permit a flow of air into the main body portion <NUM>, for example as a result of a suction created by a fan (not shown) provided within the main body portion <NUM>. An outlet vent <NUM> may be provided on an opposite side of the main body portion <NUM> to the inlet vent <NUM>, such that the flow of air within the main body portion <NUM> may be directed through and/or past the components of the main body portion <NUM>, including an energy window <NUM> and an energy source <NUM>, in order to perform cooling. It will be understood that additional components (not shown) may be present within the main body portion <NUM>, for example components configured to direct the flow of air, and/or components towards which the flow of air may be directed for the purpose of cooling (e.g. a PCB).

The energy window <NUM> may be provided in the housing <NUM> at a front end of the main body portion <NUM>, such that when the detachable portion <NUM> is attached to the main body portion <NUM>, the internal end <NUM> of the cavity <NUM> may align with the energy window <NUM>. Adjacent the energy window <NUM>, an energy source <NUM> is provided within the main body portion <NUM>. The energy source <NUM> may be any energy source <NUM> suitable for performing an energy-based treatment on the body of a subject. For example, in a skin care device configured to perform photoepilation, the energy source may comprise a lamp, LED, laser or other light source, configured to emit intense pulsed light of a required frequency.

The energy window <NUM> is configured to be substantially transparent to the treatment energy emitted by the energy source <NUM>, and configured to transmit treatment energy from the energy source <NUM> provided inside the main body portion <NUM> to outside the main body portion <NUM>. In particular, the energy window <NUM> is configured to transmit treatment energy from the energy source <NUM> into the cavity <NUM> of the detachable portion <NUM> in a direction having at least a component towards the primary opening <NUM>.

The main body portion <NUM> further comprises at least one communication vent <NUM>, 60T (collectively, <NUM>) configured to permit fluidic communication between the main body portion <NUM> and an internal space <NUM> of the detachable portion <NUM>. In the example shown in <FIG>, the main body portion <NUM> comprises two communication vents <NUM>, 60T at a front end of the housing <NUM> of main body portion <NUM>, the communication vents <NUM>, 60T configured to ensure fluidic communication between the internal space <NUM> of the detachable portion <NUM> and the space within the housing <NUM> of the main body portion <NUM>.

In effect, upon attachment of the detachable portion <NUM> to the main body portion <NUM>, the primary opening <NUM> may be in (indirect) fluidic communication, via the internal space <NUM> of the detachable portion <NUM> and the communication vents <NUM> of the main body portion <NUM>, with the inlet vent <NUM> and outlet vent <NUM> of the main body portion <NUM>. A flow of air may thereby be permitted between the inlet vent <NUM> of the main body portion <NUM> and the primary opening <NUM> of the cavity <NUM>.

In use, the detachable portion <NUM> is attached to the main body portion <NUM>. The face <NUM> of the personal care device <NUM> is placed against the body of the subject, the body of the subject defining a volume of air within the cavity <NUM>, and the primary opening <NUM> defining the portion of the body of the subject being treated. The user may then trigger activation of the energy source <NUM> by means of the user control <NUM>. If the skin contact sensors <NUM> determine that the face <NUM> is in contact with the body of the subject, then the energy source <NUM> is activated with a dose of treatment energy according to the skin tone of the subject as detected by the skin tone sensor <NUM>. The energy window <NUM> transmits the treatment energy from the energy source <NUM>, provided inside the main body portion <NUM>, to the cavity <NUM>, and the reflector walls <NUM> reflect, and thereby direct, the treatment energy towards the primary opening <NUM> of the personal care device <NUM>. Administering the treatment energy to the body of the subject performs the energy-based treatment on the portion of the body of the subject defined by the primary opening <NUM>. The energy source <NUM> may be controlled by a controller to ensure a sufficient dose is administered, and/or to prevent an excessive dose being administered.

In placing the face <NUM> of the personal care device <NUM> against the body of the subject during use, an air flow into and/or out of the cavity <NUM> (e.g. via primary opening <NUM>) may ordinarily be reduced. However, the secondary openings <NUM> of the present invention permit a flow of air out of the cavity <NUM>, whilst the treatment energy is transmitted towards the primary opening <NUM>. For example, air may be permitted to flow out of the cavity <NUM> via the primary opening <NUM> and/or any one or combination of the secondary openings 38T, 38B, <NUM>, 38R. Air may enter the cavity <NUM> via one or any combination of secondary openings <NUM>. Air may enter the cavity <NUM> via primary opening <NUM>. Air may leave the cavity <NUM> via one, or any combination of, the secondary openings <NUM>. Air may leave the cavity <NUM> via primary opening <NUM>.

It will be understood by the skilled person that a number of different air flow routes may be permitted by the arrangement of the primary opening <NUM>, the secondary openings 38T, 38B, <NUM>, 38R, the communication vents <NUM>, 60T, the inlet vent <NUM> and the outlet vent <NUM>. The nature and direction of each air flow route may depend, inter alia, upon the dimensions of each opening <NUM>, <NUM> and vent <NUM>, <NUM>, <NUM>, as well as the temperature reached within the cavity <NUM>, relative pressures in different parts of the personal care device <NUM>, the internal air flow rate of the main body portion <NUM>, and the degree of reduction in air flow through the primary opening <NUM>.

In one example air flow path, air may enter the main body portion <NUM> via inlet vent <NUM>, and may pass clockwise with respect to <FIG>. Air may enter detachable portion <NUM> via communication vent 60B. Air may enter into the cavity <NUM> via the secondary opening 38B. Air may leave the cavity <NUM> via primary opening <NUM>. Air may leave the cavity <NUM> via secondary opening 38T.

In another example air flow path, air may enter the main body portion <NUM> via inlet vent <NUM>, and may pass clockwise with respect to <FIG>. Air may enter the detachable portion <NUM> via communication vent 60B. Air may enter cavity <NUM> via secondary opening 38B. Air may leave via secondary opening 38T, and may re-enter the main body portion <NUM> via communication vent 60T. Air may leave main body portion <NUM> via outlet vent <NUM>. Air flow from secondary opening 38B to secondary opening 38T may draw air into the cavity <NUM> via primary opening <NUM>, which may then leave cavity <NUM> via secondary opening 38T.

In a further example air flow path, air passing through the main body portion <NUM> from the inlet vent <NUM> to the outlet vent <NUM> may draw air into the main body portion <NUM> from the internal space of the detachable portion <NUM>, which may in turn draw air into the internal space of the detachable portion <NUM> from the cavity <NUM> via secondary openings 38T, 38B, <NUM>, 38R, which may in turn draw air into the cavity <NUM> via primary opening <NUM>. In effect, the air flow within the main body portion <NUM> may draw air into the cavity <NUM> via primary opening <NUM> as a result of fluidic communication between the cavity <NUM> and the main body portion <NUM>.

It should be understood that the above example air flow paths are not necessarily exclusive. For example, each example air flow path may occur during a typical use cycle of the personal care device <NUM>, in which the device <NUM> is placed against the body, the energy source <NUM> activated, then the personal care device <NUM> is moved away from the body, before being again placed against the body in a different location and the cycle repeated. In any case, the flow of air into and/or out of and/or through cavity <NUM> performs a cooling function in the cavity <NUM>, such that air within the cavity <NUM> is cooled and/or such that the components of the cavity and adjoining the cavity <NUM>, including the reflector walls <NUM>, the face <NUM> and supporting surface <NUM>, are cooled.

<FIG> and <FIG>, collectively <FIG>, show a schematic section through a single reflector wall 36B of a cavity <NUM>. An auxiliary reflector 36A may be provided externally to the cavity <NUM> and in alignment with the secondary opening <NUM> (e.g. in the internal space <NUM>). The auxiliary reflector 36A may restrict and/or prevent a loss of treatment energy from the cavity <NUM> via the secondary opening <NUM>. The auxiliary reflector 36A may be configured to reflect treatment energy propagating from the cavity <NUM> into the secondary opening <NUM> back into the cavity <NUM> via a secondary opening <NUM> (e.g. the same secondary opening <NUM> and/or a different secondary opening <NUM>).

As shown in <FIG>, the auxiliary reflector 36A may comprise a reflective surface 37A (e.g. a planar reflective surface) substantially parallel to the reflector wall <NUM> of the cavity <NUM>. The auxiliary reflector 36A may be configured (e.g. arranged sufficiently proximate to the secondary opening <NUM> and reflector wall <NUM>) to reflect treatment energy propagating from the cavity <NUM> into the secondary opening 38B back into the cavity <NUM> via the same secondary opening 38B through which the energy left the cavity <NUM>. The auxiliary reflector 36A may reflect the treatment energy <NUM> back into the cavity <NUM> in a direction having a component towards the primary opening <NUM>, such that the treatment energy <NUM> may continue towards the body of the subject. The auxiliary reflector 36A may be disposed on or against the housing <NUM> of the detachable portion <NUM>.

As shown in <FIG>, the auxiliary reflector 36A may comprise a parabolic reflective surface 37P, the auxiliary reflector 36A being configured to reflect treatment energy propagating from the cavity <NUM> into the secondary opening 38B back into the cavity <NUM> via the same secondary opening 38B through which the energy left the cavity <NUM>. The parabolic reflective surface 37P may be configured such that its focus is located at a centrepoint of the secondary opening 38B.

As shown in <FIG>, the auxiliary reflector 36A may comprise a planar reflective surface 37A disposed substantially parallel to the reflector wall <NUM> of the cavity <NUM>, and running the length of the plurality of secondary openings <NUM> provided in the reflector wall <NUM>. The reflector wall <NUM> may comprise a reflective surface 37E on its exterior, such that treatment energy may be reflected repeatedly between the reflective surface 37A of the auxiliary reflector 36A and the exterior reflective surface 37E of the reflector wall 36B. The auxiliary reflector may thereby be configured reflect treatment energy backing into the cavity <NUM> via a different secondary opening <NUM> from the secondary opening <NUM> through which the treatment energy left the cavity <NUM>.

In an example not shown, the reflector wall <NUM> may comprise a one-way reflector, such that treatment energy being reflected from an auxiliary reflector 36A and incident upon an exterior surface of the reflector wall <NUM> may be transmitted into the cavity <NUM>, but treatment energy incident upon the reflective surface <NUM> of the reflector wall <NUM> may be reflected so as to remain within the cavity <NUM>. The secondary opening <NUM> may comprise a reflective surface <NUM> along its interior.

<FIG> shows a front view of the detachable portion <NUM> comprising at least one surface feature <NUM> and/or conduit <NUM> configured to permit fluidic communication between the cavity <NUM> and ambient air when the supporting surface <NUM> is in contact with the body of the subject. <FIG> shows a schematic section through the detachable portion of <FIG> along the line VIII-VIII.

With reference to <FIG> and <FIG>, the supporting surface <NUM> may comprise at least one surface feature <NUM> and/or conduit <NUM> configured to permit fluidic communication between the cavity <NUM> and ambient air when the supporting surface <NUM> is in contact with the body <NUM> of the subject.

The surface feature <NUM> and/or conduit <NUM> may be of any suitable shape for permitting a flow of air through the primary opening <NUM>. For example, the surface feature <NUM> and/or conduit <NUM> may be linear, or comprise a bend or kink along its length. The surface feature <NUM> and/or conduit <NUM> may be contiguous with the supporting surface <NUM>.

The surface feature <NUM> and/or conduit <NUM> may comprise a C-shaped groove 62A or channel as shown in <FIG>, or alternatively a straight-sided groove 62B or channel as shown in <FIG>.

Additionally or alternatively, the surface feature <NUM> and/or conduit <NUM> may comprise at least one protrusion <NUM> (e.g. a plurality of bumps) as shown in <FIG>. The protrusion may be configured to ensure an imperfect contact between the supporting surface <NUM> and the body <NUM> of the user.

Additionally or alternatively further still, the surface feature <NUM> and/or conduit <NUM> may comprise at least one conduit 62D provided beneath the supporting surface <NUM>, as shown in <FIG>.

One end of each conduit surface feature <NUM> and/or conduit <NUM> may terminate within the cavity <NUM>, proximate to the primary opening <NUM>. Another end of each conduit may terminate on an exterior surface of the housing <NUM> of the detachable portion <NUM>, in communication with ambient air. In use, the supporting surface <NUM> is placed against the body <NUM> of the subject. The surface feature <NUM> and/or conduit <NUM> is configured to permit a flow of air through (e.g. into and/or out of) the primary opening <NUM> when the personal care device <NUM> is placed against the body <NUM> of the subject. In combination with the secondary openings <NUM>, the groove may permit a flow of air into and/or out of (e.g. through) the cavity <NUM> during operation of the personal care device <NUM>. For example, the groove may permit air entering the cavity <NUM> via the secondary opening <NUM> to exit the cavity <NUM> via the primary opening, whilst the personal care device is used and thus the supporting surface <NUM> is placed against the body/skin of the subject.

Preferably, a width dimension of each surface feature <NUM> and/or conduit <NUM> may be between <NUM> and <NUM>, more preferably between <NUM> and <NUM>. Preferably, a height or depth of each surface feature <NUM> and/or conduit <NUM> may be greater than <NUM>, more preferably between <NUM> and <NUM>. Nevertheless, the skilled person will be able to determine the number, shape and dimensions of the surface feature <NUM> and/or conduit <NUM> according to the parameters of the personal care device <NUM> and the nature of the application.

Variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the principles and techniques described herein, from a study of the drawings, the disclosure and the appended claims. A single processor or other unit may fulfil the functions of several items recited in the claims. A computer program may be stored or distributed on a suitable medium, such as an optical storage medium or a solid-state medium supplied together with or as part of other hardware, but may also be distributed in other forms, such as via the Internet or other wired or wireless telecommunication systems.

Claim 1:
A personal care device (<NUM>) configured to perform an energy-based treatment on a portion of a body of a subject,
the personal care device comprising:
a main body portion (<NUM>) including an energy source (<NUM>); and
a cavity (<NUM>) having a primary opening (<NUM>), the cavity being configured to transmit treatment energy from the energy source to the primary opening,
wherein the primary opening is configured to be placed against the body during use of the personal care device to define the portion of the body being treated by means of the treatment energy, and to define a volume of air within the cavity,
wherein the cavity comprises a secondary opening (<NUM>) arranged at a distance from the primary opening and at a distance from the body when the primary opening is placed against the body and configured to permit a flow of air via the secondary opening and, thereby, a flow of air out of the cavity into the main body portion whilst treatment energy is transmitted from the energy source to the primary opening,
characterized in that the personal care device (<NUM>) comprises a detachable portion (<NUM>) configured to be detachable from the main body portion (<NUM>) of the personal care device, the detachable portion comprising the cavity (<NUM>), the primary opening (<NUM>) and the secondary opening (<NUM>).