Strong pulsed light skin or hair care device

Abstract

An intense pulsed light IPL skin or hair care device in which an illumination pattern is applied to the skin and return light from the skin is detected. The return light is analyzed to determine skin properties, and the light source is controlled in accordance with the skin properties.

Description

Technical Field

[0001] The present invention relates to intense pulsed light (IPL) hair or skin treatment devices. Background Art

[0002] It is well known that phototherapy is used for hair removal and reducing hair growth.

[0003] Consumer home-use light hair removal devices are available on the market, such as the Lumea(TM) from Philips(TM). Compared with professional devices for permanent light hair removal that use a fluence of over 10 J / cm 2 , home-use devices typically take the form of hand-held devices that use intense pulsed light (IPL) technology from, for example, a xenon flash lamp with a relatively low fluence (e.g., 6.5 J / cm 2 ).

[0004] Light is absorbed by the hair roots and hair follicles present in the skin. Due to the relatively high energy density of the light, the hair roots and hair follicles are significantly heated. By using an appropriate configuration of light energy, i.e., wavelength, intensity, and pulse duration, selective heating of the hair roots and desired temporary or permanent damage to the hair follicles can be achieved.

[0005] IPL technology uses a flash lamp to deliver intense, visible, broad-spectrum light pulses, generally in the visible spectral range of 400 nm to 1200 nm. For example, a cut-off filter is used to selectively filter out shorter wavelengths, especially potentially harmful ultraviolet light. The resulting light has a spectral range targeted at specific structures and chromophores, especially melanin in hair. IPL has some similarities with laser treatment in that they both use light to heat and destroy the target. Different from a laser that uses single-wavelength light and usually only matches one chromophore and thus only treats one condition, IPL uses a broad spectrum.

[0006] The assessment of skin properties is a desirable feature of intense pulsed light (IPL) devices, such as hair removal devices. Achieving high-precision and high-reliability measurements of skin properties (such as scattering and absorption coefficients) enables subsequent features, such as treatment personalization and device positioning for body areas.

[0007] Therefore, there is a need for an IPL device capable of determining skin properties.

[0008] US2021 / 322098 discloses an IPL device with a skin property sensor, such as for skin temperature measurement, or for example, optical measurement of scattering or reflection, or acoustic measurement, or electrical property measurement.

[0009] US2022 / 047333 discloses another IPL device that has an imaging unit and a displacement sensor for determining the position and / or orientation of the device relative to the body.

[0010] US2021 / 220667 discloses a skin light treatment device in which the reflection of illumination light is measured in order to monitor optical tissue properties and then a treatment plan is determined using treatment light.

[0011] US2016 / 374758 discloses an IPL device with a sensor for measuring skin parameters such as hue or color. The sensing is based on optical reflection measurement, for example.

[0012] EP3842002 discloses an IPL device having a sensor capable of providing user feedback. The sensor provides position and movement information so that it can be determined which areas have been treated. The device also has a skin contact sensor and a skin tone sensor, such as an optical sensor.

[0013] GB2583683 discloses another IPL device having a sensor for skin tone or color sensing.

[0014] US2005 / 045189 discloses an IPL device in which a marker film with a pigment is used to indicate that an area has been irradiated. Skin tone measurement and infrared or ultraviolet sensing of the degree of sun exposure are also mentioned. SUMMARY OF THE INVENTION

[0015] The present invention is defined by the claims.

[0016] According to an example of one aspect of the present invention, there is provided an intense pulsed light (IPL) skin or hair care device, comprising:

[0017] a light source for delivering IPL light for a skin or hair care function;

[0018] an optical system for outputting from the light source a lighting pattern applied to the skin, wherein the lighting pattern includes an initial pattern with spatial variations, the initial pattern including irradiated and non-irradiated areas of the skin;

[0019] a light sensor for detecting return light from the skin; and

[0020] a controller for controlling the light source to adjust the personal care function,

[0021] wherein the controller is configured to:

[0022] analyze the output of the light sensor to determine skin properties by comparing the spatial profile of the reflected return light with the initial pattern, thereby performing a reflected spatial profile measurement; and

[0023] Control a light source according to skin properties to adjust personal care functions.

[0024] The present invention utilizes the light source of an IPL device for Reflective Spatial Profile Measurement (RSPM). The returned light is, for example, not directly reflected light but light scattered within the skin tissue. The device is, for example, a photoepilator device.

[0025] The illumination pattern creates a highly predictable illumination pattern on the skin. The skin properties, such as scattering and absorption coefficients, are determined by irradiating the skin with a known spatially varying pattern, thereby obtaining the irradiated and non-irradiated regions of the skin.

[0026] The radiation that enters the skin and propagates within the skin before reflection causes light reflection from the non-irradiated regions of the skin. The higher the scattering within the skin tissue, the more light is reflected from the non-irradiated regions of the skin. Thus, compared to the known initial pattern, the spatial profile of the reflected radiation contains information about the scattering and absorption coefficients of the skin, which can be determined via inverse analysis. Such known analysis techniques have actually been used to determine the absorption and scattering coefficients of different skin regions of an individual, thereby discovering measurable differences between different skin regions and between individuals of different genders and ages.

[0027] The pattern is, for example, generated by independently addressing the light source elements of an array of light sources in an on or off state, thus creating a highly precise and well-defined spatial pattern of light that varies predictably in one or more dimensions. These illumination patterns are applied directly to the skin.

[0028] The light that enters the skin is scattered and reflected and is detected by a light sensor, which is, for example, positioned near the output of the IPL device in the form of one or more light sensor strips. The light sensor strip(s) is positioned along (at least) the dimension in which the emitted spatial light pattern varies, such that the spatial variations of the reflected light can be detected. These spatial variations can be evaluated by known methods to determine the skin properties.

[0029] The skin properties can then be used to calculate factors such as the possible body location of the IPL device, and thus adjust the properties of the output light during subsequent IPL therapy, or decide to completely block the therapy mode.

[0030] Skin properties, for example, include one or more of the following:

[0031] Scattering coefficient;

[0032] Absorption coefficient;

[0033] Skin albedo;

[0034] Skin extinction coefficient.

[0035] The light source preferably comprises an array of semiconductor light sources.

[0036] The light source may further comprise a filter which is used to filter the light directly emitted by the light source to prevent it from reaching the light sensor. This solves the problem of effectively shielding the light sensor from the light directly emitted by the light source, such that they only detect the light that has propagated to / through the skin.

[0037] The controller is configured, for example, to determine the angle between the device and the skin based on the output of the light sensor. The application angle of the light source can be controlled, or the angle can be determined and taken into account, so as to know the expected pattern of the light irradiated on the skin.

[0038] The controller is configured, for example, to operate the light source at a first intensity and analyze the corresponding output of the light sensor to determine the skin properties; and to control the light source at a second intensity greater than the first intensity to provide a personal care function.

[0039] Therefore, the same light source is used in different modes with different intensities to perform skin analysis functions and skin or hair treatment functions.

[0040] The controller is configured, for example, to:

[0041] if skin is detected, control the light source to emit IPL pulses according to the skin properties, and if no skin is detected, inhibit the IPL pulses; or

[0042] if a first skin area is detected, control the light source to emit IPL pulses according to the skin properties, and if a second skin area is detected, inhibit the IPL pulses.

[0043] Therefore, high-intensity IPL light can be delivered only to the skin. For some skin areas, such as the eyelid skin, it can also be inhibited.

[0044] The controller is configured, for example, to control the light source according to the skin properties by selecting the wavelength, intensity, irradiation area size and / or irradiation shape of the IPL light. Therefore, various properties of the IPL treatment light can be adapted.

[0045] The present invention also provides a computer-implemented method for determining skin properties, the method comprising:

[0046] Controlling a light source of an intense pulsed light (IPL) skin or hair care device to deliver an illumination pattern to the skin, wherein the illumination pattern comprises an initial pattern with spatial variations, the initial pattern comprising an irradiated area and a non-irradiated area of the skin;

[0047] Detecting the light returning from the skin;

[0048] Analyze the detected return light to determine skin properties by comparing the spatial profile of the reflected return light with an initial pattern, thereby performing reflected spatial profile measurement; and

[0049] Provide a control signal for the light source based on the skin properties, the control signal being for setting the characteristics of the IPL light for skin or hair care functions.

[0050] The method uses a light source to determine skin properties and then determines a suitable control for the light source for IPL treatment.

[0051] Skin properties include, for example, one or more of the following:

[0052] Scattering coefficient;

[0053] Absorption coefficient;

[0054] Absorption coefficient;

[0055] Skin albedo;

[0056] Skin extinction coefficient.

[0057] The method may include determining the angle between the device and the skin based on the detected return light. This can be used to achieve a correct interpretation of the return light.

[0058] The method may include: operating the light source at a first intensity and analyzing the corresponding light sensor output to determine skin properties; and providing a control signal for the light source to operate the light source at a second intensity greater than the first intensity to provide a personal care function.

[0059] Thus, different light intensities are used for skin analysis and skin treatment.

[0060] The method may include:

[0061] If skin is detected, provide a control signal to control the light source to emit IPL pulses, and if skin is not detected, inhibit the IPL pulses; or

[0062] If a first skin area is detected, provide a control signal to emit IPL pulses, and if a second skin area is detected, inhibit the IPL pulses.

[0063] The present invention also provides a computer program including computer program code, which is adapted to implement the method defined above when the program runs on a computer.

[0064] With reference to the embodiments (one or more) described below, these and other aspects of the present invention will become apparent and be elucidated. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] For a better understanding of the present invention and to more clearly show how to implement the present invention, reference will now be made, by way of example only, to the accompanying drawings, in which:

[0066] Figure 1 shows an intense pulsed light (IPL) skin or hair care device;

[0067] Figure 2 shows, in cross-section, the configuration of a light source and a light sensor;

[0068] Figure 3 shows the most basic example of a light source and a sensor;

[0069] Figure 4 shows an example having two light sensor strips;

[0070] Figure 5 shows an example having more 1D light sensor strips forming a 2D lattice pattern;

[0071] Figure 6 shows a first polarization-based filtering device;

[0072] Figure 7 shows a second barrier-based filtering device;

[0073] Figure 8 shows Figure 2 a light source and shows how to process the illumination pattern;

[0074] Figure 9 shows how to use device angle determination;

[0075] Figure 10 shows a sequence of light source patterns in the form of columns of illuminated light source elements, and this Figure 10 shows the signal received at the light sensor; and

[0076] Figure 11 shows a control method. DETAILED DESCRIPTION

[0077] The present invention will be described with reference to the accompanying drawings.

[0078] It should be understood that the detailed description and specific examples, while indicating exemplary embodiments of the apparatus, systems and methods, are intended for illustrative purposes only and are not intended to limit the scope of the present invention. These and other features, aspects and advantages of the apparatus, systems and methods of the present invention will become better understood from the following description, the appended claims and the drawings. It should be understood that the drawings are merely schematic and are not drawn to scale. It should also be understood that in all the drawings, the same reference numerals are used to indicate the same or similar parts.

[0079] The present invention provides an intense pulsed light (IPL) skin or hair care device, in which an illumination pattern is applied to the skin and the return light from the skin is detected. The return light is analyzed to determine skin properties, and the light source is controlled based on the skin properties.

[0080] Figure 1 An intense pulsed light (IPL) skin or hair care device 100 is shown. The device includes a light source 102 for delivering IPL light for skin or hair care functions, and a light sensor 104 for detecting the return light from the skin 120. The light source 102 generates an illumination pattern. The device is, for example, a handheld hair removal device.

[0081] Optionally, an optical system 106 is provided for delivering the illumination pattern from the light source 102 to be applied to the skin.

[0082] The light source 102 includes, for example, a 2D array of semiconductor light source elements, such as LEDs, semiconductor lasers, or VCSELs. The light source elements are individually addressable. The addressing pattern of the array creates the illumination pattern. The light source array is capable of producing at least two intensities of light: an intensity sufficient to provide intense pulsed light therapy; and a lesser amount of intensity, but still sufficient to promote enough light into the skin to scatter and reflect at a substantial intensity.

[0083] The light source elements are independently addressable such that any single light source element can be in an off or on state, and that state is independent of the state of any other light source element in the light source array.

[0084] Thus, a given arrangement of on and off states on the light source array generates an output pattern of spatial light. The emitted spatial light pattern can be described as light intensity values as a function of the two spatial dimensions of the light source array. The light source elements are arranged in a known spatial relationship with each other such that knowing which light source elements are currently in their on and off states is sufficient to know the emitted spatial light pattern.

[0085] The light sensor 104 includes, for example, a set of linear light sensor strips such that a single strip sensor is capable of determining the variation of light intensity along its single dimension. For example, each 1D light sensor can be a CCD- or CMOS-based light sensor, consisting of a linear array of photosensitive pixels.

[0086] A controller 110 controls the light source 102 to adjust the personal care function and also switches between a low-intensity skin analysis mode and a high-intensity treatment mode.

[0087] As described below, the controller has software modules that include a skin property module 110a for determining skin properties, a body position module 110b, and a device angle module 100c for determining the angle between the device 100 and the skin 120.

[0088] The controller performs an analysis of the output of the optical sensor to at least determine skin properties (and optionally angle and position information), and then controls the light source based on the skin properties during a subsequent processing stage.

[0089] The device performs reflectance spatial profiling using the light source of the IPL device in this way. The illumination pattern creates an illumination pattern that causes an illuminated area of the skin to be opposite to a non-illuminated area. The return light is not only the directly reflected light, but also the light that is internally scattered within the skin tissue (path 122). The radiation that enters the skin and propagates along this path 122 before reflection causes light reflection from the non-illuminated area of the skin. The higher the scattering within the skin tissue, the more light is reflected from the non-illuminated area of the skin. Therefore, compared with the known initial pattern, the spatial profile of the reflected radiation contains information about the scattering and absorption coefficients of the skin, which can be determined via inverse analysis.

[0090] Figure 2 A cross-section of the structure is shown. The Figure 2 It is shown that the device has a layered structure, where the light source 102 and the optical sensor are separate layers of the device.

[0091] Figure 3 The most basic examples of the light source and the optical sensor are shown. A single 2D optical sensor bar 200 is positioned such that it bisects the light source array 202 along one axis and extends along the entire array in the direction of the orthogonal axis. Figure 3 The first illumination pattern (all light sources off) on the left and the second illumination pattern (alternate rows of light sources on) on the right are shown. Thus, the optical sensor can detect the spatial variation of light along one dimension (column direction) of the light source array.

[0092] Figure 4 An example with two optical sensor bars 200a, 200b is shown. The first one is as Figure 2 shown, and the second one is perpendicular to it within the plane of the light source array. Thus, when combined, the two optical sensor bars can detect the spatial variation of light in two dimensions of the light source array.

[0093] Figure 5 An example with more 1D optical sensor bars forming a 2D lattice pattern is shown, where there are many optical sensors on both axes, evenly distributed along the length of each axis. Thus, the combined optical sensors are able to detect the spatial variation of light over the entire surface of the light source array with a resolution limited by the size of the gaps in the lattice.

[0094] Since the light sensor is positioned between the light source array and the output to the skin, the lattice of the light sensor can be configured such that the gaps are aligned with the respective light sources in the light source array to ensure sufficient illumination. Each 1D light sensor outputs a set of one-dimensional intensity and position data for each pixel along its length. This forms a 1D reflected spatial profile.

[0095] A device in the form of a filter can be provided to interrupt the direct path of light from the light source to the light sensor. The filter ensures that as much as possible only the light that reaches the skin and is reflected is detected by the light sensor, rather than light directly from the light source.

[0096] There are a variety of potential systems for the filter, which include polarization-based systems and barrier systems.

[0097] A first example is shown in Figure 6 where a linear polarization filter 300 is placed over the output of the light source element such that all output light has linear polarization. The linear polarizer 300 is, for example, a linear polarization filter that encapsulates the light sensor(s). A cross-polarization filter 302 is provided over the light sensor. Thus, light emitted directly by the light source is filtered before entering the light sensor, but light that has scattered in the skin and thus lost its polarization is allowed to pass through to be detected at the light sensor.

[0098] Figure 7 A second example is shown in

[0099] where a physical barrier 400 is provided around the light sensor. The barrier is optically opaque and conforms to the skin such that when pressure is applied between the device and the skin, any path of light that does not return from the skin is blocked.

[0099] There can be additional optical components between the light source array and the skin, such as Figure 1 the component 106 shown in

[0100] This can include optical elements built directly into the light source component, as well as external components such as collimating lenses. Then, for a given emitted spatial light pattern that is the input to the optical component, an optical model can be used to describe the output spatial pattern. Such optical models can be determined experimentally or can be obtained by simulating the effect of the optical component on the given emitted spatial light pattern.

[0100] As described above, the light source can be used in a light therapy mode or a skin sensing mode.

[0101] In the therapy mode, settings such as pulse duration, duty cycle, intensity, and (if available) wavelength can be controlled. These settings can be applied equally to the entire light source array, or they can be for each light source element separately. For example, non-uniform intensities may be required across the light source array.

[0102] The controller generates, for example, a binary value indicating whether a therapy pulse can be initiated or whether a therapy pulse should be inhibited.

[0103] In the sensing mode, the controller can send specific predefined settings to the light source array to create a sequence of emitted spatial light patterns, such as a set of binary switch values for all light sources in the array. The spatial light pattern can be time-varying.

[0104] Skin parameters determined in the sensing mode include, for example, one or more of the following:

[0105] Skin albedo, ω;

[0106] Skin extinction coefficient, β;

[0107] Skin absorption coefficient, μa;

[0108] Skin scattering coefficient, μs.

[0109] When using a 2D sensor array, the skin properties can also be calculated as a function of 2D spatial coordinates across the light source array region.

[0110] These calculations are performed by Figure 1 the skin property module 110a.

[0111] The body position module 110b determines the possible body positioning of the device based on the determined skin properties. It can consist of a machine learning algorithm trained on the skin properties to output a device position prediction, such as one of a limited set of body parts on which the model has been trained (e.g., "knee", "leg", "forearm", etc.).

[0112] The limited set can also consist of only two categories: "safe for IPL" or "unsafe for IPL", where the algorithm has been trained on a specific set of allowed or disallowed body parts.

[0113] The device angle module 110c determines the possible angle between the output plane of the device and the skin.

[0114] Figure 8 Shows Figure 2 the light source, and shows how the illumination pattern is processed.

[0115] The left figure 400 shows the sensed light with respect to an opaque surface, the middle figure 402 shows the sensed light with respect to the skin, and the right figure 404 shows the sensed light with respect to any object. The difference in the sensed signals can be used to determine whether an IPL pulse should be allowed (step 410) and to classify the skin (step 412).

[0116] Figure 9Illustrates how to use device angle determination. The Figure 9 Schematically shows that the illumination pattern provided to the skin depends on the device angle. It can be performed as a calibration step before the main sensing method. The goal is to determine the angle of the IPL device to the skin such that the difference in the illuminated skin area due to this angle can be taken into account in the main set of skin property calculations.

[0117] Before starting the skin property test, the controller relays a specific set of spatial light pattern instructions to the light source array. In one example, these instructions detail the following sequence of spatial light patterns:

[0118] (i) The first spatial light pattern illuminates only an entire column of the light source array.

[0119] (ii) The second spatial light pattern illuminates only the next entire column of the light source array.

[0120] (iii) This process is repeated until the end of the array is reached in one dimension and then repeated in the other dimension. For example, for a 6×10 light source array, this will result in a total of 16 spatial light source patterns.

[0121] After each output spatial light source pattern is emitted, the reflected light is detected by the light sensor and output as a 1D reflected spatial profile. The 1D reflected spatial profile takes the form of, for example, a single steep peak with a specific amplitude and width.

[0122] Figure 10 Illustrates the sequence of light source patterns in the form of illuminated columns of light source elements as described above, and the Figure 10 Illustrates the signal received at the light sensor. The light sensor signal has a peak at the position corresponding to the position of the illuminated column of light source elements.

[0123] The device angle algorithm sequentially receives all the 1D reflected spatial profiles and uses them to calculate a device angle prediction. This method relies on the fact that when the IPL device is at an angle, equal-sized illuminated columns will create different areas of the illuminated skin and corresponding lower intensities depending on their position on the device. Thus, the farther a given column is from the skin, the larger the illuminated area and the lower the intensity. The greater the angle between the IPL device and the skin, the greater the difference in the illuminated area and intensity between consecutive columns.

[0124] Therefore, for each 1D reflected spatial profile, the device angle algorithm calculates the amplitude and width of the peak. The algorithm then calculates the average change in amplitude and peak width between each consecutive 1D reflected spatial profile. Thus, a function that correlates the change in amplitude and peak width with the device angle is applied. This function can be determined experimentally or by simulation.

[0125] The device angle prediction is relayed to the controller, which can block the therapy mode based on the magnitude of the device angle prediction.

[0126] The device angle prediction can also be used by the skin property algorithm, which can then equalize the wavelengths of the 1D reflection space profile or apply a scale factor based on the device angle prediction to the 1D reflection space profile to adjust the amplitude accordingly.

[0127] Figure 11 A control method is shown.

[0128] In step 500, the user of the IPL device places the device against their skin.

[0129] In step 502, the controller initiates a sensing mode, for example, before allowing the therapy mode to occur. The controller can switch the IPL device from the therapy mode to the sensing mode at regular intervals during the normal use of the device. In the sensing mode, the intensity of the emitted light is kept below an acceptable minimum.

[0130] In step 504, the controller relays an instruction to generate a spatial light pattern to the light source array. The spatial light pattern is generated in step 506. It can be constant or vary over time.

[0131] In step 508, if the optical component 106 is present, the illumination pattern is modified by the optical component 106.

[0132] In all cases, in step 510, the final illumination pattern irradiates the skin. Some of the light is scattered by the skin before being reflected back to the light sensor of the device.

[0133] The controller can relay a single or multiple instructions to be followed. For example, the controller can first relay a spatial light pattern suitable for calculating the device angle prediction and subsequently relay a spatial light pattern suitable for determining the skin properties. The relayed spatial light pattern will depend, for example, on the number of available light sensors. The spatial light pattern varies spatially along the axis of at least one light sensor.

[0134] In the case where there is only one light sensor, the spatial light pattern can be a set of bright and dark columns, alternating along the same axis as the light sensor. The scattered light impinges on the light sensor and is detected as a voltage variation along its length. The 1D reflection space profile is relayed to the analysis algorithm. For example, when the output spatial light pattern is a set of alternating bright and dark "columns" as described above, the 1D reflection space profile is detected as a sine curve of voltage / light intensity, where the wavelength is twice the initial column width and the amplitude depends on the albedo and extinction coefficient of the skin. The average intensity depends on the albedo.

[0135] In the presence of two optical sensors, two spatial light patterns can be relayed, the first being a single light source as described above, and the second being alternating columns of light and dark orthogonal to the first pattern, i.e., the variation occurs in the other dimension. These spatial light patterns can be relayed to be output one after another in quick succession. The scattered light impinges on the two optical sensors and is detected as a voltage variation along its length. Two 1D reflected spatial profiles (one for each optical sensor) are relayed to an analysis algorithm. Each individual 1D reflected spatial profile describes the intensity variation in one dimension.

[0136] Instead of continuously providing an illumination line, a "checkerboard" output spatial light pattern can be created, having spatial variations of light and dark in both dimensions. In this case, the 1D reflected spatial profiles from the two optical sensors can be recorded simultaneously. The checkerboard pattern can result in all the 1D reflected spatial profiles being recorded at once.

[0137] In all cases, the reflected light is received in step 512 such that 1D reflected profiles are generated by the optical sensors.

[0138] In the case of using a polarization-based filter, the light scattered in the skin will lose its polarization and thus will not be completely blocked by the filter. In the case of using a filter in the form of a physically opaque barrier, some of the light traveling via the skin path bypasses the barrier and impinges on the optical sensor(s), while the direct path is blocked.

[0139] Once the 1D reflected spatial profiles have been recorded, known inverse analysis methods can be used to determine the skin properties of the skin area that has been tested. The skin properties are determined in step 514. For example, for each 1D reflected spatial profile:

[0140] (i) The skin albedo ω is estimated by evaluating the average intensity value of the 1D reflected spatial profile. In particular, the average intensity is used as an input to a function created based on experimental data, and for a given average intensity input, the function outputs a predicted skin albedo value.

[0141] (ii) The skin extinction coefficient β is estimated using the estimated skin albedo and the amplitude of the 1D reflected spatial profile. In particular, the amplitude and the skin albedo can be used as inputs to a function created based on experimental data, and for a given amplitude and skin albedo, the function outputs a predicted skin extinction coefficient.

[0142] (iii) The skin absorption coefficient μa and the skin scattering coefficient μs are calculated by solving the following equations for μa and μs:

[0143] β = μa + μs

[0144] ω = μs / β

[0145] Then, the skin properties determined for each 1D reflection space profile can be relayed to other algorithms to perform subsequent functions.

[0146] When multiple 1D reflection space profiles have been recorded and thus multiple sets of skin properties have been calculated, there are various options for how to process this data. In the simplest case, the values of all skin properties can be averaged across the light sensors, thereby creating a single set of skin properties to output. Prior to averaging, outliers in the skin property data can be detected and removed.

[0147] In other cases, these sets of skin properties can be relayed individually to subsequent algorithms, where the identification information (e.g., which light sensor they came from) is retained.

[0148] In step 516, the body position algorithm determines the body position. For example, it can receive a set of averaged skin properties and process these properties to output a body position prediction with a confidence value. The body position prediction and its confidence value are relayed to the controller, and based on the body position prediction and the confidence value, the controller can then determine whether it is safe to switch the IPL device from the sensing mode to the therapy mode based on the body position prediction. The controller can, for example, adjust the therapy settings based on the body position prediction in step 518, or allow or disallow therapy. If the confidence value is too low, the controller can maintain the device in the therapy mode and complete the main process again.

[0149] The present invention enables a semiconductor array-based IPL device to perform skin property testing, which was previously only possible under controlled laboratory conditions. Once determined, the skin properties can be used to control useful functions in the IPL device, such as obtaining a prediction of the position of the IPL device on the body, adjusting the light property settings for different skin types, or allowing or disallowing all treatment pulses based on the body position.

[0150] The illumination pattern used according to the present invention includes a spatially varying initial light pattern that includes an illuminated region of the skin and a non-illuminated region of the skin. In particular, an array of illuminated and non-illuminated regions can be used that forms a checkerboard pattern of multiple rows or columns of illuminated and non-illuminated regions. Generally, the illumination pattern has at least two illuminated regions and at least two non-illuminated regions, and preferably, has multiple illuminated regions and multiple non-illuminated regions. These illuminated and non-illuminated regions form, for example, a regular array.

[0151] From a study of the drawings, the disclosure, and the appended claims, those skilled in the art can understand and implement variations of the disclosed embodiments when practicing the claimed invention. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality.

[0152] The functions performed by a processor can be performed by a single processor or multiple separate processing units, which together can be considered to constitute a "processor". In some cases, such processing units can be remote from each other and communicate with each other in a wired or wireless manner.

[0153] The fact that certain measures are only cited in mutually different dependent claims does not indicate that a combination of these measures cannot be used advantageously.

[0154] A computer program can be stored / distributed on a suitable medium, such as an optical storage medium or a solid-state medium provided together with or as part of other hardware, but can also be distributed in other forms, such as via the Internet or other wired or wireless telecommunication systems.

[0155] If the term "adapted to" is used in a claim or the specification, it should be noted that the term "adapted to" is intended to be equivalent to the term "configured to". If the term "means" is used in a claim or the specification, then note that the term "means" is intended to be equivalent to the term "system", and vice versa.

[0156] Any reference signs in the claims shall not be construed as limiting the scope.

Claims

1. A intense pulsed light (IPL) skin or hair care device, comprising: A light source (102) for delivering IPL light for skin or hair care functions; An optical system for outputting from the light source a generated illumination pattern applied to the skin, wherein the illumination pattern includes a spatially varying initial pattern that includes illuminated and non-illuminated regions of the skin; A light sensor (104) for detecting the return light from the skin; and A controller (110) for controlling the light source to adjust a personal care function, wherein the controller is configured to: Analyze the output of the light sensor to determine skin properties by comparing the spatial profile of the reflected return light with the initial pattern, thereby performing a reflected spatial profile measurement; and Control the light source according to the skin properties to adjust the personal care function.

2. The device according to claim 1, wherein the skin properties include one or more of the following: Scattering coefficient; Absorption coefficient; Skin albedo; Skin extinction coefficient.

3. The device according to claim 1 or 2, wherein the light source (102) includes a semiconductor light source array.

4. The device according to any one of claims 1 to 3, wherein the light source (102) includes filters (302, 400) for filtering the light directly emitted by the light source from the light sensor.

5. The device according to any one of claims 1 to 4, wherein the controller is configured to determine the angle between the device and the skin according to the output of the light sensor.

6. The device according to any one of claims 1 to 5, wherein the controller is configured to: Operate the light source at a first intensity and analyze the corresponding output of the light sensor to determine skin properties; and Control the light source at a second intensity greater than the first intensity to provide the personal care function.

7. The device according to any one of claims 1 to 6, wherein the controller is configured to: If skin is detected, control the light source by emitting IPL pulses according to the skin properties, and if no skin is detected, inhibit IPL pulses; or If a first skin region is detected, control the light source by emitting IPL pulses according to the skin properties, and if a second skin region is detected, inhibit IPL pulses.

8. The device according to any one of claims 1 to 7, wherein the controller is configured to control the light source by selecting the wavelength, intensity, illumination area size, and / or illumination shape of the IPL light according to the skin properties.

9. A computer-implemented method for determining skin properties, comprising: (506) Controlling a light source of an intense pulsed light (IPL) skin or hair care device to deliver an illumination pattern to the skin, wherein the illumination pattern includes a spatially varying initial pattern that includes illuminated and non-illuminated regions of the skin; (512) Detecting the return light from the skin; (514) Analyze the detected return light to determine skin properties by comparing the spatial profile of the reflected return light with the initial pattern, thereby performing reflected spatial profile measurement; and (518) Provide a control signal for the light source according to the skin properties, the control signal being used to set the characteristics of the IPL light for skin or hair care functions.

10. The method according to claim 9, wherein the skin properties include one or more of the following: Scattering coefficient; Absorption coefficient.

11. The method according to claim 9 or 10, including determining the angle between the device and the skin according to the detected return light.

12. The method according to any one of claims 9 to 11, including: Operating the light source at a first intensity and analyzing the corresponding output of the light sensor to determine skin properties; and Providing a control signal for the light source to cause the light source to operate at a second intensity greater than the first intensity to provide the personal care function.

13. The method according to any one of claims 9 to 12, including: If skin is detected, providing a control signal to control the light source to emit IPL pulses, and if no skin is detected, suppressing the IPL pulses; or If a first skin area is detected, providing a control signal to emit IPL pulses, and if a second skin area is detected, suppressing the IPL pulses.

14. A computer program, including computer program code, which is adapted to implement the method according to any one of claims 9 to 13 when the program runs on a computer.

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