FIELD OF THE INVENTION

The present invention relates to an apparatus for treating skin by means of intense pulsed light (IPL) and methods of treating the skin using intense pulsed light and use of such an apparatus.

BACKGROUND OF THE INVENTION

Skin treatment apparatus is known in the art for treatment of, for example, cosmetic purposes such as hair depilation, minimisation of skin blemishes or skin rejuvenation, as well as dermatological treatment of skin conditions such as acne or rosacea. The skin is exposed to dosages of radiation such as from a laser source or light source where the radiation is targeted to the skin and the energy intensity and pulse duration is controlled. In hair depilation, the radiation source is targeted to cause heating of the hair root causing the hair root to die.

Apparatus for use in treating the skin using intense pulsed light (IPL) in particular is now increasingly available for non-professional use, i.e., for the consumer market. Accordingly, there is an associated risk of side effects to the skin through misuse. This may be in the form of skin irritation and pain through the effect of burning or pigment change.

GB2496895 discloses an apparatus including a light source, a control unit and a base unit. The control unit removably docks from the base and comprises a sensor which can detect skin tone. This control unit is therefore positioned on the skin and detects the skin tone and is then replaced into the base unit wherein the base unit then determines the power level of radiation to be generated by the light source. The head unit (20) is then repositioned onto the skin at the location for which the skin tone has been determined and the skin is treated with a pulse of light without the requirement for the user to select an energy level output. This means that the step of the user selecting the energy to be output from the light source is removed thus reducing the potential harmful effect of a user misusing the apparatus.

WO02/085229 also discloses a device for treating skin by means of radiation pulses such as a laser source. The aim of the invention disclosed in WO02/085229 is again to reduce undesirable side effects on the skin such as skin irritation and pain through misuse of the device. This is achieved through detecting a biophysical property of the skin such as the skin tone. The device comprises a housing (3) which is portable and can be placed on or moved over skin (7) to be treated. The housing (3) accommodates a radiation source, in particular a laser source (9) such as a laser diode. The housing is positioned on the skin and an image is recorded of the part of the skin situations directly in front of an exit opening (15). The positions of the hair root (39) of the hairs (41) are determined and the laser source (9) is manipulated in order that the hair roots (39) are successively heated in such a manner that they die. Protection against an impermissible overdose of the laser pulse, however, is achieved by using a detector (43) which detects, for example, the temperature of the skin resulting from exposure to a series of test laser pulses. The detector measures the temperature of the skin after each pulse to ensure that a maximum temperature is not exceeded. In such a manner the permissible dose of energy from a laser source is controlled.

WO02/085229 discloses a further embodiment wherein a detector is utilised which measures the scattering coefficient and/or absorption coefficient of the skin for light of a predetermined wavelength and the pulse dose is determined by means of the scattering coefficient and/or absorption coefficient of the skin.

There are problems associated with the prior art arrangements. GB2496895 determines the light energy pulse dependent upon skin tone, however, relies on a user then repositioning a treatment head onto a correct location for which the skin tone has been determined. It is unlikely that positioning of the treatment head accurately reflects the positioning of the detector thus giving the possibility of incorrect output energy. Further, there is significant time delay between sensing the skin tone and the time of the treatment. WO02/085229 overcomes the problem of inaccurate positioning of the treatment head by utilising a head which incorporates both a detector for detecting a parameter of the skin such as temperature, scattering coefficient and/or absorption and treats the skin dependent on this outcome. Whilst this is possible when utilising a laser pulse there are distinct safety issues associated with the use of laser pulses.

Referring toFIGS. 1A-1Ca prior art system is schematically presented as a block diagram showing how an IPL system functions.FIG. 1Aidentifies components in a prior art system and includes an energy storage device (20), typically comprising a capacitor, is arranged to release energy to the flashlamp (22) which in turn outputs a pulse of light energy to the skin under operation of the lamp trigger circuit (24). The energy storage device (20) is charged by a charge circuit (26) where the charge circuit (26) and lamp trigger circuit (24) are under operation of the control circuit (28). A user input (30) is provided such as a trigger which is depressed to enable the control circuit (28) to cause actuation of the lamp trigger circuit (24) causing release of charge from the energy storage device (20) to the flashlamp (22). In order to control the value of energy stored by the energy storage device (20) an input is provided to the control circuit (28) which is either from a sensor (32) arranged to measure a skin parameter such as skin tone as represented inFIG. 1Aor by a user selected input described in more detail with respect toFIG. 1B.

Represented inFIG. 1Bis a schematic representation of the change over time of the light output, the user input, the capacitor voltage and the capacitor charging. Prior to time T1a user turns the apparatus on and the output power required for treatment of the skin is determined. In most prior art systems this is determined by a user visually comparing their skin tone against a chart and manually selecting a power level. In GB2496895 this is determined by a control unit having a sensor to determine the preferred power output dependent on the skin tone thereby removing the requirement for the user to make a comparison with a known scale. At T1the control circuit (28) charges the capacitor during which time the capacitor voltage increases until T2is reached. The time between T2and T3represents the time in which the capacitor is charged until the user operates the user input (30) between T3and T4. At T4the charge on the capacitor is released to the flashlamp and the light pulse is released onto the skin as represented by the curve between T4and T5. The cycle is repeated as necessary on another area of skin.

FIG. 1Cpresents the change in light intensity over time dependent on the power output required. As such if the sensor or manual user input requires a power output of 7J/cm2then the capacitor is charged to 400V. Alternatively, if the skin tone is fair or light, then an energy output of 5J/cm2may be more appropriate and the capacitor is charged to a voltage of 338V.

The applicant has realised that there are significant limitations associated with prior art arrangements. The significant time delay associated with sensing a skin parameter such as the skin tone, subsequently charging the capacitor on the basis of the skin tone and causing energy release from the capacitor gives a significant delay to a user causing uncertainty in a user's mind as to whether the apparatus is actually operated correctly and further meaning that it is possible and likely that the apparatus has actually been moved relative to the skin before the energy pulse is discharged. This could lead to safety implications where the device was removed from the skin and was still enabled to discharge the energy. Accordingly, as described inFIG. 2, the applicant has determined that the capacitor voltage could be changed continuously or at regular time intervals on the basis of a changing measured sensor output whereby the skin tone reading is continuously or regularly being taken. This means that the effect of a user moving the apparatus before actuation of the user input would be mitigated. This would also mean that the energy stored ready for discharge by the energy storage device would be continuously adjusted, (charged or discharged) corresponding to the latest skin tone reading. This is presented inFIG. 2showing how the sensor measures different skin tone across the skin.

SUMMARY OF THE INVENTION

As presented inFIG. 2there is continuous (meaning repeating or regular) sensor measurement between the time that the apparatus is switched on at T0following which a valid sensor measurement is taken. On the basis of this sensor measurement the capacitor charging starts at T1and as shown, the capacitor voltage increases up until a voltage is achieved at T2corresponding to the sensor measurement at that time. As the sensor measurement then identifies that a lower energy output from the flashlamp is required the capacitor ceases to charge between time T2and T3and during this time residual energy left in the capacitor is released thus enabling the capacitor voltage to decrease. Between time T3and T4again the capacitor is charged due to the sensor measurement identifying that a greater energy output is required the capacitor voltage increases. The user input is then activated at T4. However, the sensor measurement is recorded at T5and the sensor measurement identifies that the required energy output should be less than would be achieved by the stored energy or the capacitor at that time. Accordingly, at T5the capacitor charging ceases and the capacitor voltage is decreased. During the time between T5and T6the user input has been actuated, however, the capacitor voltage must decrease. The problem with this is that reduction of the capacitor voltage to reflect the required output for the current sensor measurement takes significant time which may be, for example, between three to ten seconds. This is undesirable in an automated system wherein the energy output is dependent on a sensor output as again it may lead to further movement of the apparatus on the skin thereby creating further delays to further sensor measurements being recorded and again would cause difficulties for a user in knowing when the apparatus was functioning correctly.

The present invention provides an improved apparatus that can be used by an individual who is not a medical practitioner thus ensures fast, effective treatment without any of the safety implications or disadvantages identified above.

According to an aspect of the present invention there is a skin treatment apparatus comprising:a light source comprising a light emitting element for transmitting light energy to the skin and a charge storage device for discharging an energy dose to the light emitting element;at least one sensor for measuring a parameter of the skin;a control system configured to determine a treatment energy dose to be delivered, this being derived using the sensor measurement; andi) wherein the control system is arranged to terminate discharge of the charge storage device upon delivery of the treatment energy dose; and/orii) wherein the charge storage device comprises a plurality of individual charge storage elements, and the control system is arranged to control discharge of the plurality of individual charge storage elements to deliver the treatment energy dose; and/oriii) wherein the control system is arranged to enable charging of the charge storage device in a two or more stage operation, wherein in a first stage charging is to an intermediate energy level, and in a second or further stage to an energy level sufficient to deliver the treatment energy dose; and/oriv) wherein the control system is arranged to modulate discharge of the charge storage device to deliver the treatment energy dose.

The claimed invention (and the alternative aspects defined) provide an extremely beneficial system where in each aspect the technical problem of unwanted time delay associated with charging or discharging of the charge storage device in sole dependence on the current or most recently measured skin parameter such as skin tone is removed. This speed means there is little possibility of significant movement of the apparatus between sensing a skin parameter and carrying out the treatment. Furthermore, usability is significantly improved as a user will not have any uncertainty as to whether the treatment has occurred as there will be substantially zero time delay between user activation to cause treatment and delivery of the treatment energy dose.

In one aspect the apparatus is preferably a hair depilation apparatus.

In one aspect the control system is arranged to terminate discharge of the charge storage device upon delivery of the treatment energy dose and/or before discharge is complete. This is beneficial as the discharge can be terminated as necessary to deliver only the treatment energy dose. This further means that the charge storage device can be charged independently of the sensor measurement of the treatment area. Control of the energy supply to the skin is therefore effectively controlled upon release. This is rather than being controlled upon energy supplied to the charge storage device. As such, charging of the charge storage device can be completed quickly and there is no requirement to release charge from the charge storage device due to the energy stored thereon being too high. The charge storage device can be charged to a voltage that may be the same each time the apparatus is used.

It will be appreciated that the treatment energy dose may be controlled upon release from the charge storage device, so the treatment energy dose may be free discharge of the charge storage device and/or a modulated discharge that may extend the treatment time period. This means that the actual light intensity contacting the skin can be controlled, and the light output delivered over an extended time frame if required to reduce intensity for the user.

The treatment energy dose can be manipulated before discharge for example through a user input, thereby increasing or decreasing the treatment energy dose for example. However, it will be appreciated that the control system terminates discharge of the charge storage device once the treatment energy dose has been delivered where the treatment energy dose can be determined solely on the basis of the sensor measurement or to include an additional input such as a user input to provide improved efficacy for a specific user.

In one aspect the charge storage device comprises a plurality of individual charge storage elements, and the control system is arranged to control discharge of the plurality of individual charge storage elements to deliver the treatment energy dose. The control system is beneficially arranged to selectively discharge one or more of the plurality of charge storage elements to deliver the treatment energy dose. This means that one or more individual charge storage elements can be activated and preferably discharged independently of the other individual charge storage elements. For example, if two individual charge elements are provided, one charge element can be discharged independently of the other. If there are three charge element for example two charge elements can be discharged simultaneously or sequentially and the other left charged, or for example all three charge elements can be discharged again simultaneously, sequentially or a combination thereof, depending on the determined energy treatment dose. Again, this provides the benefit in that there is no delay associated with a user inputting their requirement to activate the apparatus and release the energy to the skin and this actually occurring. As such, control of the energy output to the skin is achieved through discharge of one or more individual charge storage elements. A plurality of charge storage elements may be charged, again preferably independently of the sensor measurement meaning that the output energy can be adjusted to the required treatment intensity with no time delay. It is beneficial that in order to achieve the desired energy output to the skin, two or more of the individual charge storage elements may be charged to different voltages. It will further be appreciated that the control system may be arranged to modulate discharge of energy from the plurality of charge storage elements.

In a further aspect the control system is arranged to enable charging of the charge storage device in a two or more stage operation, wherein a first stage charging is to an intermediate energy level, and a second or further stage to an energy level sufficient to deliver the treatment energy dose. The charge storage device can therefore be effectively charged to a minimum voltage between energy doses supplied to the skin and the charge storage device may effectively be ‘topped up’ dependent on the sensor measurement. In such an embodiment there may be a small time delay between a user activating the apparatus to the treatment energy dose being supplied. In such an embodiment, the control system is arranged to partially charge the charge storage device dependent on the sensor measurement.

In one aspect the control system is arranged to modulate discharge of the charge storage device to deliver the treatment energy dose. This provides a further alternative means of ensuring that the correct treatment energy dose may be delivered to the light emitting element and subsequently to the user derived using the sensor measurement. An energy modulation arrangement is beneficially provided to modulate the supply of treatment energy dose to the light emitting element. The modulation arrangement beneficially comprises an electronic switch such as a Mosfet. Pulse width modulation or pulse duration modulation may be utilised to control discharge of the charge storage device meaning that the output light from the light emitting element can be manipulated. This means that the intensity of the light hitting the user's skin may be controlled, and may be changed over time. Utilising pulsed switch modulation effectively switches the discharge of the charge storage device from an ‘off’ to an ‘on’ configuration and the longer the switch is on compared to the off period, the higher the energy supplied to the light emitting element is meaning that the intensity of the light transferred to the user is increased. This means that again it is unnecessary to charge the charge storage device after receipt of a sensor reading. Unwanted time delay associated with charging or discharging of the charge storage device where dependence on the current measured skin parameter such as skin tone is removed.

The apparatus preferably further comprises a housing arranged to accommodate the light emitting element and the sensor. This means that accuracy of the sensed skin parameter with respect to the actual area of the skin treated is maintained. The light emitting element and sensor are preferably in fixed locations relative to each other as defined by the housing.

The apparatus preferably comprises an indicator for providing information regarding the sensor measurement and/or the treatment energy dose. The indicator is preferably a display. This provides a safety check in that the user will be provided with an indication of the sensor measurement and/or treatment energy dose meaning that operation of the apparatus can be stopped if the indication is deemed severely compromised.

The control system is beneficially arranged to control charging of the charge storage device prior to and/or at the same time as determination of the treatment energy dose. This means that there is no time delay associated with making a measurement of a parameter of the skin and subsequently charging the charge storage device. The control system is beneficially configured to enable charging of the charge storage device and/or one or more individual charge storage elements to a predetermined voltage.

In operation the sensor is beneficially arranged to record multiple skin parameter measurements prior to determination of the treatment energy dose. This means that the actual or correct skin treatment area for which a sensor reading is recorded is treated in the event, for example, that the user accidently moves the apparatus.

The control system is beneficially configured to determine the treatment energy dose based on a plurality of the multiple skin parameter measurements. As such the control system may continuously determine the necessary output treatment energy dose at the exact location on which the apparatus is positioned.

The control system is beneficially configured to control supply of the treatment energy dose to the light emitting element. This controlled supply of the treatment energy dose to the light emitting element may take a variety of forms and the controlled supply may be adjusted in that the energy pulse may be modulated. There is beneficially an energy modulation arrangement configured to modulate supply of the treatment energy dose to the light emitting element. The output energy treatment may therefore be controlled in terms of shape, meaning that, for example, a square energy pulse could be output thereby controlling the light intensity, contacting the user, and/or the time period of discharge could be changed, for example increased.

A discharge control element is beneficially provided arranged to terminate the energy supplied from the charge storage device. This is beneficially activated once the treatment energy dose is reached. This provides significant benefits. The charge storage device can be charged to a voltage that allows a potentially greater energy output to be released than actually required for the treatment energy dose. This may be predetermined and can always be the same value meaning that the requirement to be dependent on the sensor output for the treatment of the skin at that moment is removed as the energy supplied from the charge storage device can be terminated through provision of a discharge control element once the predetermined energy is released. Residual charge can be left on the charge storage device. The discharge control element beneficially comprises a switch beneficially comprising an electronic switch such as a Mosfet switch. The switch is beneficially controlled by the control system.

The control system is beneficially further arranged to measure a discharge parameter, and the control system is beneficially configured to feedback information regarding the discharge parameter into determination of the treatment energy dose. This provides a benefit in that there is a feedback of a discharge parameter such as the energy output treatment dose from the light emitter meaning that the actual output energy dose can be compared to the calculated energy treatment dose and any error can be compensated. The discharge parameter could be, for example, the output current, or final voltage of the charge storage device. This improves the accuracy of the actual energy output meaning that the apparatus is effectively self-correcting.

The control system may be configured to independently control discharge of each of the individual charge storage elements in the event of provision of a plurality of individual charge storage elements.

In one embodiment the control system is configured to enable energy release from the plurality of charge storage elements sequentially. Alternatively, the control system may be configured to enable energy release from the plurality of charge storage elements substantially simultaneously.

The control system is beneficially configured to at least partially charge the charge storage device to a charge value such as voltage derived from at least one previous operational parameter (e.g. treatment energy dose) of the apparatus. This would mean that a minimum voltage to which the charge storage device could be charged between treatments may be made dependent on previous operation of the apparatus. For example, the charge storage device may be charged to a minimum voltage determined from previous measurements. The minimum voltage could, for example, correspond to the minimum skin tone measured in the last ten treatments thereby effectively reducing the additional charging required for the charge storage device to reflect the voltage required for the next treatment.

The control system is beneficially provided with a memory configured to record a plurality of treatment energy doses output to the light emitting element and further comprises a processor configured to determine the lowest treatment energy output dosage, the control system further configured to charge the charge storage device to the lowest energy output dosage.

Determination of treatment energy setting by the apparatus automatically on the basis of the sensed skin parameter removes the necessity for the user to determine skin tone (or other physical parameter) or take extra steps in the treatment process. However, it is possible that the user would like some level of control over the automatic selection. Any automatic selection of output would be pre-determined to be suitable for the majority of users. However, some users may find the treatment painful (or otherwise too intense), or ineffective, and may desire some manual control. This could be achieved at the same time as automatic selection by allowing the user to select alternative ‘ranges’ of automatic selection. The apparatus therefore further beneficially includes a user input for changing the treatment energy dose. The user input preferably comprises an override function to the determined treatment energy dose. The treatment energy dose may be increased or decreased. The change in treatment energy dose is preferably predetermined.

A user could select a ‘Gentle’ mode which reduces the treatment energy dose by a pre-determined amount e.g. the treatment energy dose could be reduced by a fixed value or percentage across the range of determined treatment energy doses. Alternatively, the maximum value of treatment energy dose may be limited.

Alternatively, a user may select an ‘Intense’ mode which increases the output of the determined treatment energy dose by a pre-determined amount e.g. the energy dose may be increased by a fixed value or percentage across the range of determined treatment energy doses.

The treatment energy dose may be changed dependent on a user selected input parameter comprising a body parameter. This may for example be body location, hair colour, hair thickness etc. The range of treatment energy dose may be changed for improved suitability to the individual user.

The user input may alter another output treatment parameter such as energy dose length or pulse shape.

When utilising the user input for changing the treatment energy dose indication is beneficially provided by the indicator, which is preferably a visual display where a bar of lights may display or display a representation of sensor measurement and/or treatment energy dose which changes if the user input is activated.

The present invention also extends to a method of treating the skin through transmission of light energy to the skin from a light emitting element comprising the steps of:measuring a parameter of the skin with at least one sensor;configuring a control system to determine a treatment energy dose to be delivered from a charge storage device to the light emitting element using the sensor measurement;discharging the treatment energy dose from the charge storage device to the light emitting element to cause light energy release therefrom, and:i) terminating discharge of the charge storage device once the treatment energy dose is delivered and/or before discharge is complete; and/orii) providing a plurality of individual charge storage elements and controlling discharge of one or more of the plurality of individual charge storage elements to deliver the treatment energy dose; and/oriii) charging the charge storage device in a two or more stage operation wherein the first stage is to an intermediate energy level and the second stage is to an energy level sufficient to deliver the treatment energy dose; and/oriv) modulating discharge of the charge storage device to deliver the treatment energy dose.

It will be appreciated that the method of treating the skin may be carried out by a non-medical practitioner and is particularly suitable for home use for the purpose of cosmetic skin treatment and in particular hair depilation.

The present invention also extends to a method of cosmetically treating the skin as hereinbefore described.

The present invention also extends to a method of cosmetic hair depilation as hereinbefore described.

It is extremely important in the present invention that when determining the skin parameters such as skin tone, a robust method of apparatus is utilised since any error could result in an adverse incident meaning the incorrect energy dosage could be applied to the skin. This may result, in the worst case, in damage to the skin through excess treatment energy dose being applied, or alternatively result in an energy dose being too low meaning that the treatment is ineffective.

According to a second aspect of the present invention there is skin treatment apparatus comprising:a light source for transmitting an energy dose to the skin;at least a first and second sensor, each sensor independently capable of measuring a skin parameter;a control system arranged to control operation of the light source in dependence on the first and second sensor measurements.

Such an apparatus provides a simple yet effective manner of determining a skin parameter such as skin tone. The result from the first and second sensors can be used together to determine a more accurate skin parameter with reduced error, thus ensuring accuracy and efficacy of the treatment energy dose.

The apparatus beneficially further comprises a housing for accommodating the light source, the housing having a transmission window for transmission of the energy dose therethrough. The housing is beneficially arranged to accommodate the first and second sensors, the housing including at least one sensor window therein. The relative positions of the transmission window and sensing window are therefore fixed. There is beneficially provided a first sensor window for the first sensor and a second sensor window for the second sensor.

The first and second sensors are beneficially disposed spaced from the transmission window. Although it is considered possible to determine a skin parameter on the exact area of the skin to be treated, this is difficult to achieve due to the optics required being complex and the measurement system having to be resistant to high energy light treatment doses. As such, the first and second sensor windows are disposed spaced from the transmission window. There are, therefore, provided at least two sensing zones each capable of independently measuring a skin parameter. The skin parameter is usually skin tone and this is achieved by transmitting sensing radiation onto the skin and receiving reflecting radiation from the skin surface. The intensity of the received radiation is representative of the tone of the skin.

The housing beneficially comprises a user contact element defining the transmission window and the first and second sensor windows, the first and second sensors being disposed adjacent the transmission window in the user contact element. The user contact element may comprise a plate. The plate may be planar or may be curved in profile. The transmission window may comprise an aperture in the user contact element. There may be a transparent window provided in the housing intermediate the skin and the light source, however, it will be appreciated that this is not essential. The transmission window may be defined by a recess provided in the housing defined by a peripheral edge of the housing.

The transmission window beneficially partially bridges the linear separation between the first and second sensor windows. The first and second sensors are therefore beneficially placed either side of the window. The remainder of the bridge may be made up of a housing portion and in particular a peripheral edge of the housing defining the transmission window and the first and second sensors. This bridge is minimised to improve accuracy in respect of representative skin parameter of the treatment area.

The control system beneficially comprises a processor configured to calculate from the first and second sensor measurement the treatment energy output.

The control system may be beneficially configured to determine a valid skin parameter reading. This may be determined by the difference between the two sensor measurements being below a predetermined threshold.

In one embodiment the processor is configured to determine a skin parameter measurement that is determined to be the safest or best treatment setting to be used. For example, the safest treatment energy setting would be on the lowest skin parameter measurement from the two sensors. Alternatively, the highest measurement, the average or another calculation could be used.

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

