阅读说明：本技术 用于确定针对个人护理设备的皮肤接触的系统和方法 (System and method for determining skin contact for a personal care device ) 是由 S·J·范德艾尔曾 G·库伊杰曼 R·伊斯梅尔 元兆瑞 B·G·格布雷 于 2021-06-08 设计创作，主要内容包括：本公开涉及用于确定针对个人护理设备的皮肤接触的系统和方法。提供了一种被配置为在受试者的皮肤上执行个人护理操作的系统。系统包括处理单元和个人护理设备。个人护理设备包括具有孔的壳体,孔布置在壳体上,使得当个人护理设备与皮肤接触并且用于在皮肤上执行个人护理操时,孔邻近皮肤。个人护理设备还包括成像单元,该成像单元设置在壳体内,并且布置为利用穿过孔进入个人护理设备的光来获取邻近孔的皮肤的图像,其中,在系统的皮肤接触检测模式中,成像单元的焦平面与孔对齐。处理单元被配置为在皮肤接触检测模式中接收由成像单元在皮肤接触检测模式中获取的一个或多个图像,并处理该一个或多个图像以确定个人护理设备是否与皮肤接触。(The present disclosure relates to systems and methods for determining skin contact for a personal care device. A system configured to perform a personal care operation on the skin of a subject is provided. The system comprises a processing unit and a personal care device. The personal care device includes a housing having an aperture, the aperture being disposed on the housing such that the aperture is adjacent the skin when the personal care device is in contact with the skin and used to perform a personal care operation on the skin. The personal care apparatus further comprises an imaging unit arranged within the housing and arranged to acquire an image of the skin adjacent the aperture using light entering the personal care apparatus through the aperture, wherein in a skin contact detection mode of the system a focal plane of the imaging unit is aligned with the aperture. The processing unit is configured to receive, in the skin contact detection mode, one or more images acquired by the imaging unit in the skin contact detection mode and to process the one or more images to determine whether the personal care device is in contact with the skin.)

1. A system (40) configured to perform a personal care operation on the skin of a subject, the system (40) comprising:

a processing unit (46); and

personal care apparatus (2) comprising:

a housing (4) having an aperture (10) arranged in the housing (4) such that the aperture (10) is adjacent the skin when the personal care device (2) is in contact with the skin and is to be used to perform a personal care operation on the skin;

an imaging unit (44) disposed within the housing (4) and arranged to acquire images of skin adjacent the aperture (10) using light entering the personal care device (2) through the aperture (10), wherein in a skin contact detection mode of the system (40) a focal plane (66) of the imaging unit (44) is aligned with the aperture (10); and is

Wherein the processing unit (46) is configured to receive, in the skin contact detection mode, one or more images acquired by the imaging unit (44) in the skin contact detection mode, and to process the one or more images to determine whether the personal care device (2) is in contact with the skin.

2. The system (40) according to claim 1, wherein the imaging unit (44) is configured such that the focal plane (66) of the imaging unit (44) is in a fixed position relative to the bore (10).

3. The system (40) according to claim 1, wherein the imaging unit (44) is configured such that the focal plane (66) of the imaging unit (44) is variable, and the imaging unit (44) is configured to adjust the focal plane (66) to align with the aperture (10) in the skin contact detection mode of the system (40).

4. The system (40) according to any one of claims 1 to 3, wherein the processing unit (46) is configured to process only a portion of the received image corresponding to one or more edges of the hole (10).

5. The system (40) according to any one of claims 1 to 4, wherein the well (10) comprises a light thru aperture cover plate (14) aligned with the well (10).

6. The system (40) according to any one of claims 1 to 5, wherein the personal care device (2) further comprises a first light source (54) arranged within the personal care device (2) to generate skin illumination light when the imaging unit (44) is to acquire the one or more images.

7. The system (40) according to any one of claims 1 to 6, wherein the processing unit (46) is configured to determine whether the personal care device (2) is in contact with the skin based on a focus quality and/or a sharpness of the image.

8. The system (40) according to claim 7, wherein the processing unit (46) is configured to analyze the received one or more of the images to determine a value of a parameter related to focus quality and/or sharpness, and to determine whether the personal care device (2) is in contact with the skin based on the determined value of the parameter.

9. The system (40) according to any one of claims 1-7, wherein the processing unit (46) is configured to implement a machine-learned (ML) model that receives as input one or more of the images and determines whether the personal care device (2) is in contact with the skin based on a classification of the received one or more of the images.

10. The system (40) according to any one of claims 1 to 9, wherein the personal care device (2) further comprises a second light source (12) for generating processing light for performing the light-based personal care operation.

11. The system (40) according to any one of claims 1 to 10, wherein the personal care device (2) is configured such that a personal care operation is performed on the skin through the aperture (10).

12. The system (40) according to any one of claims 1-11, wherein the system (40) is further configured to: -performing the personal care operation if the processing unit (46) determines that the personal care device (2) is in contact with the skin, and/or-preventing the personal care operation from being performed if the processing unit (46) determines that the personal care device (2) is not in contact with the skin.

13. The system (40) according to any one of claims 1 to 11, wherein the system (40) is further configured to adjust power consumption of the personal care device (2) based on whether the processing unit (46) determines that the personal care device (2) is in contact with the skin.

14. A method for determining whether a personal care device is in contact with skin, the method comprising:

receiving (101) one or more images from an imaging unit in a personal care device, wherein the imaging unit is arranged to acquire the one or more images using light entering the personal care device through an aperture in a housing of the personal care device, wherein in a skin contact detection mode a focal plane of the imaging unit is aligned with the aperture; and

in the skin contact detection mode, the received one or more images are processed (103) using a processing unit to determine whether the personal care device is in contact with the skin.

15. A computer program product comprising a computer readable medium embodying computer readable code embodied in the computer readable medium, the computer readable code being configured such that, on execution by a suitable computer or processor, the computer or processor is caused to perform the method of claim 14.

Technical Field

The present disclosure relates to personal care devices for performing personal care operations on the skin of a subject, and in particular to systems and methods for determining whether a personal care device is in contact with the skin.

Background

Various personal care devices are used when a portion of the device is in contact with or in proper proximity to the skin of a subject. Examples of such devices include devices that use various techniques, such as shaving, electrolysis, plucking, laser and light therapy (known as photo-epilation or intense pulsed light, IPL) and injection of treatment antiandrogens to exfoliate unwanted hair. Personal care devices for reducing hair growth and treating acne also require contact with the skin. Personal care devices may also be used to provide massage to a subject, provide therapy, apply patches (e.g., electrocardiogram electrodes, etc.) to a subject, and for ultrasound measurements.

Light-based epilation is a personal care operation for inhibiting hair growth by exposing the skin to a bright flash of light or light pulses, which may be referred to as IPL (intense pulsed light), where the light pulses are generated by a lamp or bulb. Alternatively, the flash or pulse may be generated using a laser or one or more Light Emitting Diodes (LEDs). Light penetrates the skin and is absorbed at the hair roots, in addition to being absorbed elsewhere. The temperature of the hair roots will increase and subsequently the temperature of the surrounding tissue will also increase. If the temperature is raised sufficiently, hair growth is inhibited. This process is called photo-pyrolysis.

Contact with the skin is required for successful treatment and to prevent the introduction of light pulses to other parts of the body, such as the eyes, which can cause injury. If no skin contact is detected, the personal care apparatus may be prevented from emitting light. Thus, a skin contact sensor may be provided for the personal care device to measure a parameter indicative of whether the personal care device is in contact with the skin. The parameter may be capacitance or contact pressure.

Similarly, the light pulses may only be suitable for certain skin types (safe for certain skin types only), and the personal care device may be prevented from emitting light if unsafe skin tones are detected. A skin tone sensor (e.g., an optical sensor) may be provided for the personal care device to measure a parameter (e.g., a melanin index) indicative of the skin tone contacted and to be treated by the personal care device.

Currently, skin contact sensors and skin tone sensors are integrated into the skin contacting portion of the personal care device. However, it is often desirable that this portion of the device be removable and interchangeable with different accessories, where each accessory may be adapted for different applications or body parts. For example, in the case of light-based personal care operations, different attachments may be provided for major body parts (e.g., arms, legs, abdominal bikini), bikini lines, face, and armpits. Currently, all accessories require a skin contact sensor and a skin tone sensor.

EP 3388011a1 discloses a processing device for an image sensor and uses the sensor in a way that addresses privacy concerns of the user and people around the user. An imaging unit 27 within the device housing includes an imaging light source 28(LED or laser) that generates light (white light/UV/visible light/IR) to enable an image sensor 30 to generate an image of the skin.

Disclosure of Invention

More and more personal care devices include an imaging unit (e.g., a camera) therein to acquire images of a region of a subject where a personal care operation is to be performed and where the personal care operation has been performed. The use of an imaging unit embedded in the personal care apparatus may provide potential benefits, such as performing process guidance via displacement measurements, and evaluating the effectiveness of personal care operations. In order to minimize the increase in cost of the personal care apparatus due to the addition of the imaging unit and associated processing circuitry, it is considered whether the imaging unit is available to perform the function of some existing sensors in the personal care apparatus, so that these sensors can be omitted. In particular, it would be beneficial to use an imaging unit to detect contact with the skin instead of requiring a dedicated skin contact sensor to detect, especially in case each individual accessory of the personal care apparatus has a respective skin contact sensor component.

It is therefore an object of the present invention to provide a system and method for determining whether a personal care apparatus is in contact with the skin using images acquired by an imaging unit.

According to a first particular aspect, there is provided a system configured to perform a personal care operation on the skin of a subject. The system includes a processing unit; and a personal care appliance. The personal care appliance comprises: a housing having an aperture disposed in the housing such that the aperture is adjacent the skin when the personal care device is in contact with the skin and is to be used to perform a personal care operation on the skin; and an imaging unit disposed within the housing and arranged to acquire an image of skin adjacent the aperture using light entering the personal care device through the aperture, wherein in a skin contact detection mode of the system a focal plane of the imaging unit is aligned with the aperture. The processing unit is configured to receive, in the skin contact detection mode, one or more images acquired by the imaging unit in the skin contact detection mode and to process the one or more images to determine whether the personal care device is in contact with the skin.

In some embodiments, the imaging unit is configured such that a focal plane of the imaging unit is in a fixed position relative to the aperture. In an alternative embodiment, the imaging unit is configured such that a focal plane of the imaging unit is variable, and the imaging unit is configured to adjust the focal plane to align with the aperture in a skin contact detection mode of the system.

In some embodiments, the processing unit is configured to process only a portion of the received image corresponding to one or more edges of the aperture.

In some embodiments, the holes include a light through hole cover plate aligned with the holes.

In some embodiments, the personal care device further comprises a first light source arranged within the personal care device to generate skin illumination light when the imaging unit acquires the one or more images.

In some embodiments, the processing unit is configured to determine whether the personal care device is in contact with the skin based on the focus quality and/or sharpness of the image. In these embodiments, the processing unit may be configured to analyze the one or more received images to determine a value of a parameter related to focus quality and/or sharpness, and to determine whether the personal care device is in contact with the skin based on the determined value of said parameter.

In an alternative embodiment, the processing unit is configured to implement a Machine Learning (ML) model that receives the one or more images as input and determines whether the personal care device is in contact with the skin based on a classification of the one or more received images. In these embodiments, the ML model may be based on any of the following: a support vector machine, a decision tree, a random forest, an artificial neural network, a deep neural network, or a convolutional neural network.

In some embodiments, the personal care device is for performing light-based personal care operations. In these embodiments, the personal care device further comprises a second light source for generating treatment light for performing light-based personal care operations.

In some embodiments, the personal care device is configured such that the personal care operation is performed on the skin through the aperture.

In some embodiments, the system is further configured to perform the personal care operation if the processing unit determines that the personal care device is in contact with the skin, and/or to prevent performance of the personal care operation if the processing unit determines that the personal care device is not in contact with the skin.

In an alternative embodiment, the system is further configured to adjust the power consumption of the personal care device based on whether the processing unit determines that the personal care device is in contact with the skin.

In some embodiments, the processing unit is separate from the personal care device. In an alternative embodiment, the personal care apparatus comprises a processing unit.

According to a second aspect, a method for determining whether a personal care device is in contact with skin is provided. The method comprises receiving one or more images from an imaging unit in the personal care device, wherein the imaging unit is arranged to acquire the one or more images using light entering the personal care device through an aperture in a housing of the personal care device, wherein, in a skin contact detection mode, a focal plane of the imaging unit is aligned with the aperture; and in a skin contact detection mode, processing the received one or more images using the processing unit to determine whether the personal care device is in contact with the skin.

In some embodiments, the imaging unit is configured such that a focal plane of the imaging unit is in a fixed position relative to the aperture. In an alternative embodiment, the imaging unit is configured such that a focal plane of the imaging unit is variable, and the imaging unit is configured to adjust the focal plane to align with the aperture in a skin contact detection mode of the system.

In some embodiments, the processing step comprises processing only portions of the received image corresponding to one or more edges of the aperture.

In some embodiments, the holes include a light through hole cover plate aligned with the holes.

In some embodiments, the method further comprises generating skin illumination light using a first light source disposed within the personal care device when the imaging unit is to acquire the one or more images.

In some embodiments, the processing step comprises determining whether the personal care device is in contact with the skin based on the focus quality and/or sharpness of the image.

In these embodiments, the processing step may include analyzing the one or more received images to determine a value of a parameter related to focus quality and/or sharpness, and determining whether the personal care device is in contact with the skin based on the determined value of the parameter.

In an alternative embodiment, the processing step includes inputting the received one or more images into a Machine Learning (ML) model, and the ML model determines whether the personal care device is in contact with the skin based on a classification of the one or more received images. In these embodiments, the ML model may be based on any of the following: a support vector machine, a decision tree, a random forest, an artificial neural network, a deep neural network, or a convolutional neural network.

In some embodiments, the personal care device is for performing light-based personal care operations. In these embodiments, the personal care device further comprises a second light source for generating treatment light for performing light-based personal care operations.

In some embodiments, the personal care device is configured such that the personal care operation is performed on the skin through the aperture.

In some embodiments, the method further includes performing the personal care operation if it is determined that the personal care device is in contact with the skin, and/or preventing performance of the personal care operation if it is determined that the personal care device is not in contact with the skin.

In an alternative embodiment, the method further comprises adjusting the power consumption of the personal care device based on determining whether the personal care device is in contact with the skin.

In some embodiments, the processing unit is separate from the personal care device. In an alternative embodiment, the personal care apparatus comprises a processing unit.

According to a third aspect, there is provided a computer program product comprising a computer readable medium having computer readable code embodied therein, the computer readable code being configured such that, on execution by a suitable computer or processor, the computer or processor is caused to perform a method according to the second aspect or any embodiment thereof.

The above and other aspects will be apparent from and elucidated with reference to the embodiments described hereinafter.

Drawings

Example embodiments will now be described, by way of example only, with reference to the following drawings, in which:

fig. 1 is an illustration of an example personal care device, according to an embodiment;

fig. 2 is a block diagram of an example system including a personal care device and a device, in accordance with various embodiments;

fig. 3 is a simplified cross-sectional view of the example personal care appliance of fig. 1;

FIG. 4(a) is another cross-sectional view of a portion of the example personal care device of FIG. 3 in contact with skin, and FIG. 4(b) is an example image taken by the imaging unit when the personal care device is in contact with skin;

FIG. 5(a) is another cross-sectional view of a portion of the example personal care device of FIG. 3 that is not in contact with the skin, and FIG. 5(b) is an example image taken by the imaging unit when the personal care device is treating a portion that is not in contact with the skin; and

fig. 6 is a flow diagram illustrating an example method for determining whether a personal care device is in contact with skin.

Detailed Description

Fig. 1 is an illustration of an example personal care device 2, according to an embodiment, the personal care device 2 being operable to apply pulses of energy (e.g., light pulses) to a skin region. It should be understood that the personal care apparatus 2 in fig. 1 is merely an example of a personal care apparatus 2 with which the present invention may be used and that the personal care apparatus 2 is not limited to the form shown in fig. 1 or to energy-based personal care apparatuses. In some embodiments, the personal care device 2 is held in one or both hands by the user during use. The personal care device 2 is used on the body of a subject (e.g., a human or an animal), and some personal care operations are performed on the body of the subject when the personal care device 2 is in contact with the skin of the subject. In some embodiments, the personal care device 2 will perform some personal care operation on the subject's skin. Some example personal care operations include, but are not limited to, removal of unwanted hair by any of shaving, electrolysis, laser, and light therapy (referred to as photo-epilation or intense pulsed light); dermatological (skin) treatments including hair growth reduction, acne treatment, phototherapy treatment, skin rejuvenation, skin firming or wine stain treatment; and pain relief.

As described herein, the personal care device 2 is operated or used by a "user" and the personal care device 2 is used on the body of a "subject". In some cases, the user and the subject are the same person, i.e. the user holds the personal care device 2 in his hand for his own use (e.g. on the skin of his legs). In other cases, the user and the subject are different people, for example, the user holds the personal care device 2 in his hand and uses it on another person.

The personal care apparatus 2 comprises a housing 4, the housing 4 comprising at least a handle portion 5 and a body portion 6. The handle portion 5 is shaped such that a user can hold the personal care apparatus 2 with one hand. The body portion 6 has a first end 8, which first end 8 is placed in contact with the skin of the subject when a personal care operation is to be performed on the body or skin of the subject.

In the embodiment shown in fig. 1, the personal care apparatus 2 is used to perform personal care operations using energy or pulses of energy (e.g., light or light pulses). Thus, in fig. 1, the first end 8 includes an aperture 10 disposed in or on the housing 4 such that the aperture 10 can be placed adjacent to (i.e., in contact with) the skin of the subject. The personal care apparatus 2 comprises one or more energy sources 12 arranged within the housing 4 for generating energy pulses to be applied to the skin of a subject via the apertures 10 and to effect a personal care operation. The one or more energy sources 12 are positioned within the housing 4 such that energy pulses are provided from the one or more energy sources 12 through the aperture 10. The aperture 10 may be in the form of an opening at the first end 8 of the housing 4. In some embodiments, the well 10 includes an aperture plate 14 that is transparent (e.g., light transmissive) to the energy pulse (i.e., the energy pulse can pass through the aperture plate 14).

In the exemplary embodiment shown in fig. 1, the aperture 10 and the aperture plate 14 (if present) have a generally rectangular shape, which creates a generally rectangular skin treatment area on the skin. It should be understood that the aperture 10 and/or the aperture plate 14 may have any other desired shape. For example, the well 10 and/or well plate 14 may be square, oval, circular, or any other polygonal shape.

The one or more energy sources 12 may generate any suitable type of energy for performing personal care operations, such as light, sound, Radio Frequency (RF) signals, microwave radiation, and plasma. In the case of an energy source 12 that generates light, the energy source 12 may be configured to generate pulses of light of any suitable or desired wavelength (or range of wavelengths) and/or intensity. For example, the energy source 12 may generate visible light, Infrared (IR) light, and/or Ultraviolet (UV) light. Each energy source 12 may include any suitable type of light source, such as one or more Light Emitting Diodes (LEDs), flash lamps (e.g., xenon flash lamps), one or more lasers, and so forth. In a preferred embodiment, the personal care apparatus 2 is used for performing photo-epilation and the energy source 12 is used for providing a powerful light pulse. For example, the energy source 12 may provide light pulses in the 560-1200 nanometer (nm) spectral content for about 2.5 milliseconds (ms) because these wavelengths heat up melanin in the hair and hair root by absorption, which will place the hair follicle in a resting phase, preventing hair regrowth. In the case of an energy source 12 that generates sound, the energy source 12 may be configured to generate pulses of sound at any suitable or desired wavelength (or range of wavelengths) and/or intensity. For example, the energy source 12 may be an ultrasound transducer.

One or more energy sources 12 are configured to provide pulses of energy. That is, the energy source 12 is configured to generate energy at a high intensity for a short duration (e.g., less than 1 second). The intensity of the energy pulse should be high enough to effect a personal care operation on the skin or body part adjacent to the aperture 10.

The illustrated personal care device 2 also includes a user control 16, which user control 16 can be operated by a user to activate the personal care device 2 to perform a desired personal care operation on the subject's body (e.g., generation of energy pulses by the one or more energy sources 12). The user controls 16 may be in the form of switches, buttons, touch pads, and the like.

Although not shown in fig. 1, the first end 8 may be shaped as a detachable attachment for a specific body part. The detachable accessory is also referred to herein as a detachable head portion. A plurality of detachable attachments may be provided, each attachment having a respective shape and a respective aperture size, and the attachment may be selected for the personal care apparatus 2 based on the body part to be treated. For example, different attachments may be provided for face, armpit, bikini wire, and generally for the body (e.g., larger body surface area). Each accessory has a respective aperture 10 and an optical diffuser 14 located in/on the aperture 10.

Although not shown in fig. 1, the personal care device 2 may include a skin tone sensor located on or within the first end 8. A skin tone sensor may be used to determine the skin tone of the skin adjacent to or in contact with first end 8. The skin tone sensor may measure a parameter indicative of skin tone and generate a time series comprising a measurement signal, the measurement signal measuring the parameter. Typically, a skin color sensor, in particular an optical hair cutter, is used in the personal care apparatus 2 to ensure that the light pulses have an intensity suitable for the type of skin treated, or to prevent the light pulses from being generated even when the skin type is not suitable for the light pulses (e.g. darker skin with a much higher melanin content).

The skin color sensor may be a light sensor and the parameter measured by the light sensor may be the intensity or level of light of a particular wavelength or wavelengths reflected from the skin. The measured intensity or level of reflected light of a particular wavelength may be indicative of skin tone. The measured intensity or level of reflected light may be based on the concentration of melanin in the skin, and thus the measured intensity or level may be indicative of the melanin concentration. Melanin concentration can be obtained by measuring the reflection of light at wavelengths of, for example, 660nm (red) and 880nm (infrared).

As mentioned above, conventional personal care devices may include a dedicated sensor for detecting when or if the personal care device is in contact with the skin. In the case of a personal care device, in particular a light epilator, a skin contact sensor is used to ensure that the personal care device is correctly in contact with the skin before generating the light pulses to avoid that the light pulses are directed into the eyes of the user or subject. Typically, these dedicated sensors can detect skin contact by measuring capacitance via a corresponding pair of electrical contacts or electrodes on the first end surface, the measured capacitance indicating whether skin contact is present. Alternatively, these dedicated sensors may detect skin contact based on the intensity or level of light measured by the light sensor, or measure contact pressure via a pressure sensor or mechanical switch. Since these dedicated skin contact sensors are typically integrated into the skin contacting portion of the personal care device, and this portion of the device can be interchanged with different accessories, a skin contact sensor is required on all accessories.

Thus, the present disclosure provides a method of detecting contact between a personal care device and skin using images acquired by one or more imaging units disposed within a housing of the personal care device, which means that no separate skin contact sensor is required on the personal care device (and no separate skin contact sensor is required on different accessories). Thus, as described further below, one or more imaging units are provided within the housing 4 and arranged to acquire images of the skin adjacent the aperture 10 using light entering the personal care device 2 through the aperture 10 (or possibly through a corresponding aperture in the case of multiple imaging units). The image or images acquired by the imaging unit are provided to the processing unit, and the processing unit processes the images to determine whether the personal care device 2 is in contact with the skin. In the embodiments described below, the personal care apparatus 2 comprises a single imaging unit which acquires images using light entering the personal care apparatus 2 through the aperture 10. However, in other embodiments, the personal care apparatus 2 may comprise a plurality of imaging units. The plurality of imaging units may be arranged to image through respective portions of the aperture 10, for example around the edges of the aperture 10, or a respective aperture may be provided for each imaging unit on the housing 4. In the case of multiple imaging units, the field of view of each imaging unit may be relatively narrow to reduce overlap of image content between acquired images. Although the embodiments described below are directed to a personal care apparatus 2 comprising a single imaging unit, the embodiments may be readily adapted to a personal care apparatus 2 using multiple imaging units, and further details of the multiple imaging unit embodiments are not described herein.

Fig. 2 is a block diagram of an example system 40 that includes the personal care device 2 and an apparatus 42 for determining whether the personal care device 2 is in contact with skin. In fig. 2, the apparatus 42 is a device separate from the personal care device 2, and thus the apparatus 42 may be in the form of an electronic device, such as a smartphone, smart watch, tablet computer, Personal Digital Assistant (PDA), laptop computer, desktop computer, remote server, smart mirror, or the like. In other embodiments, the apparatus 42 (and in particular the functionality provided by the apparatus 42) is part of the personal care device 2. In other embodiments, the functions of the means 42 described below may be distributed between the personal care apparatus 2 and the individual means 42.

The personal care apparatus 2 comprises an imaging unit 44 for acquiring an image of the skin adjacent the aperture 10 using light entering the personal care apparatus 2 through the aperture 10. Fig. 2 only shows the imaging unit 44 in the personal care apparatus 2, and it should be understood that in practice the personal care apparatus 2 comprises further components, such as an energy source 12, a power supply, a control unit, etc., in addition to the components shown. In some embodiments, as described further below, one or more light sources may be provided that are associated with the imaging unit 44 and used to generate light when the imaging unit 44 is to acquire an image. The light generated by the one or more light sources is also referred to herein as "skin illumination light", although it is understood that the light illuminates the skin only when the skin is in contact with or in close proximity to the personal care device 2. The light source is also not shown in fig. 2. The imaging unit 44 may include any suitable components for capturing an image, a plurality of images, or a series of images (e.g., a video sequence), such as a charge-coupled device (CCD) and one or more lenses and/or mirrors. In some embodiments, imaging unit 44 is a camera, such as a digital camera.

Device 42 includes a processing unit 46, processing unit 46 generally controlling the operation of device 42 and enabling device 42 to perform the methods and techniques described herein. In short, the processing unit 46 receives one or more images from the imaging unit 44 and processes the images to determine whether the personal care device 2 is in contact with the skin.

Thus, the processing unit 46 may be configured to receive images directly from the imaging unit 44 in embodiments where the apparatus 42 is part of the personal care device 2, or via another component from the imaging unit 44 in embodiments where the personal care device 2 is separate from the apparatus 42. In either case, the processing unit 46 may include or include one or more input ports or conductors for receiving images (or signals carrying information representing images) from the imaging unit 44 or other suitable components. The processing unit 46 may also include or contain one or more output ports or leads for outputting signals indicating whether the personal care apparatus 2 is in contact with the skin.

The processing unit 46 may be implemented in a variety of ways, via software and/or hardware, to perform the various functions described herein. The processing unit 46 may include one or more microprocessors or Digital Signal Processors (DSPs) that may be programmed using software or computer program code to perform the required functions and/or to control the components of the processing unit 46 to implement the required functions. The processing unit 46 may be implemented as a combination of dedicated hardware for performing some functions, such as amplifiers, preamplifiers, analog-to-digital converters (ADCs), and/or digital-to-analog converters (DACs), and a processor (e.g., one or more programmed microprocessors, controllers, DSPs, and related circuitry) for performing other functions. Examples of components that may be employed in various embodiments of the present disclosure include, but are not limited to, conventional microprocessors, DSPs, Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs), hardware used to implement neural networks, and/or so-called Artificial Intelligence (AI) hardware accelerators (i.e., processors or other hardware designed specifically for AI applications that may be used with a main processor).

The processing unit 46 may include or be associated with a memory unit 48. Memory unit 48 may store data, information, and/or signals (including images) for use by processing unit 46 in controlling the operation of device 42 and/or in performing or carrying out the methods described herein. In some embodiments, memory unit 48 stores computer readable code that is executable by processing unit 46, causing processing unit 46 to perform one or more functions, including the methods described herein. In particular embodiments, the program code may be in the form of an application program for a smartphone, tablet, laptop, computer, or server. The memory unit 48 may include any type of non-transitory machine-readable medium, such as a cache or system memory, including volatile and non-volatile computer memory, such as Random Access Memory (RAM), static RAM (sram), dynamic RAM (dram), Read Only Memory (ROM), programmable ROM (prom), erasable prom (eprom), and electrically erasable prom (eeprom), and may be implemented in the form of: memory chips, optical disks (e.g., Compact Disks (CDs), Digital Versatile Disks (DVDs), or blu-ray disks), hard disks, tape storage solutions, or solid state devices including memory sticks, Solid State Drives (SSDs), memory cards, and the like.

In the embodiment shown in fig. 2, since the apparatus 42 is shown separate from the personal care device 2/imaging unit 44, the apparatus 42 further comprises an interface circuit 50 to enable the apparatus 42 to receive images from the imaging unit 44. The interface circuitry 50 in the apparatus 42 is capable of performing data connections and/or data exchanges with other devices, including any one or more of the imaging unit 44, the personal care device 2, a server, a database, user equipment, and sensors. A direct or indirect connection (e.g., over the internet) may be made with the imaging unit 44 (or any electronic device, such as the processing device 2), and thus the interface circuit 50 may enable a connection between the apparatus 42 and a network, or between the apparatus 42 and another device (e.g., the imaging unit 44 and/or the personal care device 2), via any desired wired or wireless communication protocol. For example, the interface circuit 50 may operate using WiFi, bluetooth, Zigbee, or any cellular communication protocol including, but not limited to, global system for mobile communications (GSM), Universal Mobile Telecommunications System (UMTS), Long Term Evolution (LTE), LTE advanced, etc. In the case of a wireless connection, the interface circuit 50 (and thus the device 42) may include one or more suitable antennas for performing transmission/reception over a transmission medium (e.g., air). Alternatively, in the case of a wireless connection, the interface circuit 50 may include a mechanism (e.g., a connector or plug) that enables the interface circuit 50 to connect to one or more suitable antennas external to the device 42 for performing transmission/reception over a transmission medium (e.g., air). The interface circuit 50 is connected to the processing unit 46.

Although not shown in fig. 2, device 42 may include one or more user interface components including one or more components that enable a user of device 42 to enter information, data, and/or commands into device 42, and/or enable device 42 to output information or data to a user of device 42. The user interface may include any suitable input components, including but not limited to a keyboard, a keypad, one or more buttons, switches or dials, a mouse, a track pad, a touch screen, a stylus, a camera, a microphone, and so forth. And the user interface may include any suitable output components including, but not limited to, a display unit or screen, one or more lights or light elements, one or more speakers, a vibrating element, etc. In some embodiments, the user interface components may be used to provide an indication to the user as to whether the personal care device 2 is in contact with the skin or is in proper contact with the skin. The indication may be determined based on the processing result of the image by the processing unit 46. In embodiments, the indication may be provided as a visual indication, an audible indication, and/or a tactile indication.

It should be understood that a practical implementation of the apparatus 42 may include additional components than those shown in fig. 2. For example, the device 42 may also include a power source, such as a battery, or a component for enabling the device 42 to connect to a mains power source.

Fig. 3 is a simplified cross-sectional view of the exemplary personal care apparatus 2 of fig. 1, showing the arrangement of the imaging unit 44 in the personal care apparatus 2. In this embodiment, the apparatus 42, in particular the processing unit 46, is part of the personal care device 2 and is shown connected to the imaging unit 44. The imaging unit 44 is arranged within the housing 4 such that it can acquire images using light entering the personal care apparatus 2 through the aperture 10. A user interface component 52 is also shown connected to the processing unit 46, and the user interface component 52 is operable to provide feedback to a user of the personal care device 2 based on the processing result of the image by the processing unit 46.

Fig. 3 also shows one or more light sources 54 associated with the imaging unit 44 and used to generate light when an image is to be acquired by the imaging unit 44. When the aperture 10 is positioned against the skin, it may be difficult for the imaging unit 44 to acquire a good image of the skin due to low light conditions. Thus, the light source 54 is disposed within the housing 4 such that light generated by the light source 54 can illuminate any subject (including skin) proximate to or in contact with the aperture 10 through the aperture 10 (and the aperture plate 14, if present). The one or more light sources 54 may be LEDs or any other suitable type of light source. The one or more light sources 54 may emit white light (or colors that combine to provide white light (e.g., RGB)), light of a particular color, light having a particular spectral content, or infrared light. Illuminating the skin with different colors of light may cause the images acquired by the imaging unit 44 to include color information, so these images may be used to determine skin tone and skin contact. As another example, illuminating the skin with infrared light may cause the melanin index of the skin to be determined. Typically, the one or more light sources 54 are different from any light source 12 used to perform personal care operations.

Fig. 4(a) is another cross-sectional view of a portion of the example personal care device of fig. 3 in contact with skin 55. Fig. 4(a) shows a part of the main body portion 6 including the imaging unit 44. Two components of the imaging unit 44 are also shown, namely an image sensor 60 and an optical focusing assembly 62, the optical focusing assembly 62 comprising, in this embodiment, a single lens 64. The image sensor 60, such as a Charge Coupled Device (CCD), senses incident light and outputs an image signal (to the processing unit 46) including information about or representing the incident light. An optical focusing assembly 62 is positioned in front of the image sensor 60 for focusing incident light onto the image sensor 60. It should be understood that although only one lens 64 is shown in the optical focusing assembly 62, a typical optical focusing assembly 62 may include more than one lens 64.

According to the techniques described herein, skin contact detection is based on: whether the skin image acquired by the imaging unit 44 is focused or sharp. That is, where the acquired image includes focused skin, then the processing unit 46 may determine that the personal care device 2 is in contact with the skin and that the acquired image does not include skin, or does not include focused skinIn case, the processing unit 46 may then determine that the personal care device 2 is not in contact with the skin (or is not in proper contact with the skin). To achieve this, the imaging unit 44 (in particular the optical focusing assembly 62) is configured such that at least during a skin contact detection mode of the system 40 in which skin contact is to be detected, the focal plane 66 of the imaging unit 44 is aligned with the aperture 10. As understood by those skilled in the art, the focal plane of the lens 64, or more generally, the focal plane of the optical focusing assembly 62, is a plane perpendicular to the optical axis of the lens 64/optical focusing assembly 62 that coincides with the focal point in front of the lens 64/optical focusing assembly 62. Thus, when the personal care apparatus 2 is in contact with the skin 55, as shown in fig. 4(a), the skin 55 will be located at the aperture 10 and aligned with the focal plane 66, and the skin image acquired by the imaging unit 44 will be in focus. In fig. 4(a), various distances are labeled: image distance d_i(distance between lens 64 and image sensor 60), object distance d_o(distance between lens 64 and hole 10) and focal length l of lens 64_f。

In order to improve the detection of the personal care apparatus 2 not being in contact with the skin 55 or not being in proper contact with the skin 55, the imaging unit 44 may be configured such that the depth of field of the imaging unit 44 is narrow or small. As understood by those skilled in the art, the depth of field of the lens 64/optical focusing assembly 62 is the distance between the closest point and the farthest point from the lens 64/optical focusing assembly 62 when the imaging subject is focused. Depth of field d_fShown and indicated by dashed line 68 in fig. 4 (a). The depth of field 68 is preferably narrow enough or small enough that if the personal care device 2 is close to the skin 55 but not in proper contact with the skin 55 (i.e. is correct in order to perform a personal care operation), the skin 55 will not be in focus in the image acquired by the imaging unit 44. For example, a sufficiently narrow or small depth of field may be in the range of 2-3 millimeters (mm). Thus, if the skin 55 is more than 1-2mm from the aperture 10 of the personal care device 2, the skin 55 will not be fully focused in the acquired image.

Fig. 4(b) is an example image 70 acquired by the imaging unit 44 in the personal care apparatus 2 when the personal care apparatus 2 is in contact with the skin 55. The skin elements in the image 70 (such as various hairs on the skin) are focused and visible.

Fig. 5(a) shows the personal care apparatus 2 of fig. 4(a) spaced a small distance from the skin 55. At least during a skin contact detection mode of the system 40, in which skin contact is to be detected, the focal plane 66 of the imaging unit 44 is aligned with the aperture 10 and the skin 55 is outside the depth of field 68 of the imaging unit, which means that the image of the skin 55 taken when the personal care apparatus 2 is in this position will not be in focus. Fig. 5(b) is an example image 72 of the same area of the skin 55 as fig. 4(b) taken by the imaging unit 44 in the personal care apparatus 2 when the personal care apparatus 2 is spaced apart from the skin 55 as shown in fig. 5 (a). In fig. 5(b), it can be seen that the skin elements in image 70 are unfocused, or not clearly visible.

As mentioned above, the imaging unit 44 (in particular the optical focusing assembly 62) is configured such that at least during a skin contact detection mode in which skin contact is to be detected, the focal plane 66 of the imaging unit 44 is aligned with the aperture 10. In some embodiments, the focal plane 66 of the imaging unit 44/optical focusing assembly 62 is in a fixed position relative to the bore 10, and in particular, the focal plane is fixed at the bore 10. In other words, the focal plane remains aligned with the aperture 10 even if no skin contact is detected (i.e., even if the system 40 is not operating in the skin contact detection mode).

However, in alternative embodiments, the imaging unit 44/optical focusing assembly 62 may be configured such that the focus of the imaging unit 44/optical focusing assembly 62 is variable or adjustable when the system 40 is not operating in the skin contact detection mode to enable acquisition of a focused image of a subject not in contact with the personal care device 2/aperture 10. This may be desirable in situations where the image acquired by the imaging unit 44 may be used for purposes other than skin contact detection, such as tracking the movement of the personal care device 2 relative to a body part, or identifying where on the body the personal care device 2 is used. In these embodiments, when skin contact is to be detected (i.e. the system 40 is operating in a skin contact detection mode), the focus of the imaging unit 44/optical focusing assembly 62 is adjusted such that the focal plane is aligned with the aperture 10 to enable a focused image of the skin to be acquired when the personal care apparatus 2 is in contact with the skin.

In the embodiment shown in fig. 1, 3, 4(a) and 5(a), the imaging unit 44 and the energy source 12 share the same aperture 10 and aperture plate 14 (if present). That is, the imaging unit 44 generates an image from light entering the personal care apparatus 2 via the aperture 10, and the energy source 12 emits energy out of the personal care apparatus 2 via the aperture 10. However, in alternative embodiments, the personal care device 2 may be provided with a first aperture (i.e. the imaging unit 44 may generate an image from light entering the personal care device 2 via the first aperture) which may be used for detecting contact with the skin, and a second aperture (e.g. aperture 10) which may be used for personal care operations (i.e. energy from the energy source 12 leaves the personal care device 2 through the second aperture).

Although the embodiments of the personal care device 2 shown in fig. 1, 3, 4(a) and 5(a) are directed to performing personal care operations using energy or pulses of energy, such as light or light pulses, it should be understood that the personal care device 2 may be directed to performing other types of operations. For example, the personal care device 2 may be a shaver or a hair clipper, in which case the body portion 6 may comprise one or more cutting blades or foils for cutting hair when the body portion 6 is in contact with the skin. As another example, the personal care apparatus 2 may be an ultrasound probe for acquiring ultrasound images. In this example, the body portion 6 may include an ultrasound transducer for generating ultrasound waves, and an ultrasound receiver for receiving ultrasound waves reflected back from inside the body. In these alternative types of personal care devices, where the personal care operation is not performed via an aperture in the housing 4, the personal care device 2 is provided with an aperture 10 at a location that is in contact with the skin when the personal care device 2 is in place to perform the personal care operation, so that the imaging unit can acquire an image of the skin via the aperture 10. The aperture 10 may include an aperture plate 12 as described above.

In embodiments where the personal care device 2 does not include an aperture plate 14, the skin adjacent the aperture 10 may "bulge" or "bulge" when the personal care device 2 is in contact with the skin. In particular, if the personal care device 2 is pressed against the skin, the edges of the aperture 10 will press against the skin surface, which may cause the skin to "bulge" or "bulge" in the middle of the aperture 10 (i.e. the skin extends a short distance into the aperture 10 towards the middle of the aperture 10). In this case, since the focal plane of the imaging unit 44 is aligned with the aperture 10, the processing unit 46 is configured to process the image portions around the edges of the aperture 10 in the image, since in these portions of the image the skin will be in focus in case the personal care apparatus 2 is in contact with the skin. Thus, in these embodiments, the processing unit 46 may ignore a central portion of the acquired image where the skin may have "peaked" into the hole 10 and may be located outside the depth of field 68 of the imaging unit 44 when detecting whether there is skin contact.

In embodiments where the aperture 10 includes an aperture plate 14, the plane of the aperture plate 14 is preferably aligned with the plane of the aperture 10. In this way, the aperture plate 14 will prevent the skin adjacent the aperture 10 from "doming" into the aperture 10, and the processing unit 46 can analyze any or all portions of the image acquired by the imaging unit 44 to determine whether the personal care device 2 is in contact with the skin.

In embodiments where the personal care device 2 is used to perform a personal care operation, where skin contact is required to ensure the safety of the user and/or subject, for example, where the personal care device 2 is a light epilator or other light-based personal care device, triggering or initiating the personal care operation may be prevented unless the processing unit 46 determines that the personal care device 2 is in contact with the skin.

In other embodiments, skin contact detection may be used to adjust the power consumption of the personal care device 2. In particular, if skin contact is detected, the personal care device 2 may be caused to perform a personal care operation, whereas if skin contact is not detected, the personal care operation cannot be performed properly and the personal care device 2 may be deactivated or placed in a low power mode. For example, in case the personal care device 2 comprises a mechanical cutting element or a mechanical shaving element for cutting or shaving hair, the cutting or shaving element may be activated when skin contact is detected, such that hair may be cut, but the cutting or shaving element may be deactivated when skin contact is not detected (or it is detected that the personal care device 2 is not in contact with the skin), or the cutting speed (e.g. the motor speed) of the cutting or shaving element is reduced.

As described above, when it is to be determined whether the personal care apparatus 2 is in contact with the skin (e.g., at the moment when the personal care operation is to be performed), the imaging unit 44 acquires one or more images and supplies them to the processing unit 46. The processing unit 46 processes the image to determine whether the personal care apparatus 2 is in contact with the skin. In some embodiments, in particular in case the skin contact detection involves safety aspects, the processing unit 46 may provide an indication for each received image whether the personal care device 2 is in contact with the skin or not.

In some embodiments, the processing unit 46 analyzes all of the acquired images to determine whether there is skin contact, but in other embodiments, the processing unit 46 may crop the acquired images or otherwise analyze only a portion of the acquired images. For example, the latter case may be employed, wherein the aperture 10 does not comprise an aperture plate 14, and when the personal care apparatus 2 is pressed onto the skin, the skin bulges or protrudes into the aperture 10, so the processing unit 46 may crop the acquired image, or only analyze the outer portion of the image corresponding to the edge of the aperture 10, wherein the bulge or protrusion at the edge is minimal. On the other hand, if the aperture plate 14 is present, the processing unit 46 may crop the acquired image or otherwise analyze only an interior portion of the image corresponding to the middle of the aperture 10, where the light source associated with the imaging unit 44 may more evenly illuminate the skin.

In some embodiments, the processing unit 46 may determine whether the personal care device 2 is in contact with the skin based on whether the image is in focus (i.e., based on focus quality) and/or whether the image is sharp. The sharpness of an image is related to the sharpness of the edges of the features visible in the image. For an image, the processing unit 46 may determine that there is no skin contact if the image is not in focus/blurred and/or unclear, and the processing unit 46 may determine that there is skin contact if the image is in focus and/or clear. In these embodiments, the processing unit 46 may analyze the image to determine values of parameters related to focus quality (e.g., a measure of the degree of focus of the image) and/or sharpness (and optionally other image-related parameters, such as brightness, contrast, parameters related to the presence of skin features in the image, etc.), and compare these values to one or more thresholds or ranges related to the presence/absence of skin contact to determine whether skin contact is present. The processing unit 46 may output a signal indicating whether skin contact is present. In these embodiments, the processing unit 46 may apply conventional image processing techniques, such as, for example, techniques described in Pertuz, Said, Domenec Puig, and Miguel Angel Garci, "Analysis of focus services operators for shape-from-focus", Pattern Recognition,46.5(2013): 1415-.

In alternative embodiments, the processing unit 46 may analyze the image using or implementing a trained Machine Learning (ML) model to determine if skin contact is present. Depending on the type of ML model used, the trained ML model may receive one or more images as input, analyze the images, and output a signal indicating whether skin contact is present. For other types of ML models, the processing unit 46 may determine parameter values related to focus/focus quality and/or sharpness (and optionally other image-related parameters) and input these parameter values into the ML model. The ML model determines whether there is skin contact using the input parameter values and outputs a signal indicating whether there is skin contact. Some types of ML models that may be used include classical machine learning models, such as feature extraction performed using a support vector machine, decision trees, random forests, etc., or artificial neural networks, such as deep neural networks or convolutional neural networks, that have multiple layers between input and output layers and identify linear or nonlinear relationships between input and output layers.

In some embodiments, prior to deploying the ML model in the personal care device 2, the ML model is first trained, for example using training data comprising skin images from a population of subjects. In this case, the training data may include a plurality of images acquired when the personal care device 2 is at different distances/heights from the skin of various different subjects (in which case the images will be blurred/out of focus), and a plurality of images acquired when the personal care device 2 is known to be in contact with different portions of the skin (of one or more different subjects), in which case the images will be in focus. Optionally, some or all of the training data may be acquired in a controlled user test prior to deployment of the personal care device 2, or alternatively, some or all of the training data may be acquired from users of the personal care device 2 who share their images and provide corresponding skin contact/non-skin contact annotations for those images. Optionally, the training data may also comprise images of other subjects or backgrounds visible to the imaging unit 44 during use of the personal care device 2. The training data is used to train the ML model, for example, using a supervised ML approach. The training method generates a deployable training classifier algorithm that outputs "skin contact present" or "skin contact not present" based on one or more input images.

In other embodiments, the ML model may be trained during an initial calibration process performed when the user or subject first uses the personal care device 2. In this case, the user may be instructed to collect training data for the ML model by having the imaging unit 44 acquire a plurality of images when it is known that the personal care device 2 is not in contact with the skin, and having the imaging unit 44 acquire a plurality of images when it is known that the personal care device 2 is in contact with different parts of the skin (of one or more different subjects). In a further embodiment, both methods may be used, i.e. the ML model may be trained prior to deployment and a calibration procedure is performed in order to refine the ML model for the specific skin features of the subject.

The flow chart in fig. 6 illustrates an example method for determining whether the personal care device 2 is in contact with skin according to the techniques described herein. One or more steps of the method may be performed by system 40 (e.g., processing unit 46 in device 42) in conjunction with any of memory unit 48 and interface circuit 50 of device 42 and/or imaging unit 44, as the case may be. Processing unit 46 may perform one or more steps in response to executing computer program code, which may be stored on a computer-readable medium (e.g., memory unit 48).

Although not shown in fig. 6, an initial step of the method (when the system 40 is operating in the skin detection mode) may include the imaging unit 44 acquiring (generating) one or more images. When one or more images are acquired, the focal plane of the imaging unit 44 is aligned with the aperture 10 of the personal care apparatus 2.

In step 101, one or more images are received from the imaging unit 44. The images may be received directly from the imaging unit 44, for example, in real time or near real time, as the imaging unit 44 generates the images. Alternatively, the image may be received from the imaging unit 44 in the separate personal care apparatus 2 via the interface circuit 50. As mentioned above, the imaging unit 44 is arranged to acquire one or more images using light entering the personal care apparatus 2 through the aperture 10. The focal plane of the imaging unit 44 is aligned with the aperture 10 at least when the system 40 is operating in a skin contact detection mode. In the case of an imaging unit 44 whose focal plane is not adjustable, the focal plane of the imaging unit 44 will be aligned with the aperture 10 even when the system 40 is not operating in the skin contact detection mode. In the case of an imaging unit 44 whose focal plane is adjustable, the focal plane of the imaging unit 44 may still be aligned with the aperture 10 even when the system 40 is not operating in the skin contact detection mode.

In step 103, the processing unit 46 processes the one or more images (when the system 40 is operating in the skin contact detection mode) to determine whether the personal care device 2 is in contact with the skin.

In some embodiments of step 103, the processing unit 46 may process the image to determine whether the image is in focus and/or sharp, thanks to the arrangement of the focal plane of the imaging unit 44 when the system 40 is operating in the skin contact detection mode. In some embodiments, if the processing unit 46 determines that the image is not focused or not sharp, the processing unit 46 may determine that the personal care device 2 is not in contact with the skin. In these embodiments, if the processing unit 46 determines that the image is focused and/or sharp, the processing unit 46 may determine that the personal care device 2 is in contact with the skin.

In some embodiments of step 103, the one or more images are processed using the trained ML model to determine whether the personal care device 2 is in contact with the skin. The ML model may perform an evaluation or classification of each image to determine whether the personal care device 2 is in contact with the skin. In some embodiments, the ML model receives the images directly and performs all the required analysis and processing on the images to determine if there is contact between the personal care device 2 and the skin. This is especially true for ML models that use artificial neural networks (e.g., deep neural networks). In other embodiments, such as where a classical ML model is used, processing may be performed on the image prior to providing the image to the ML model, such as determining values for one or more features related to the image, and (optionally, in addition to the image) may also provide these values to the ML model to perform analysis to determine whether the personal care device 2 is in contact with the skin.

Then, although not shown in fig. 6, a signal indicating whether the personal care device is in contact with the skin may be output. In some embodiments, the indication may be simply "skin contact present" or "skin contact not present".

The signal may be provided to the apparatus 42 or to a user interface component of the personal care device 2 and is configured such that the user interface component indicates whether the personal care device 2 is in contact with the skin. For example, if it is determined that the personal care device 2 is not in contact with the skin, the signal may cause a red light on the personal care device 2 to illuminate. Likewise, if it is determined that the personal care device 2 is in contact with the skin, the signal may cause a green light on the personal care device 2 to illuminate. The user of the personal care device 2 will be able to use these indications to determine whether or not to trigger a personal care operation at the current location of the personal care device 2. As another example, where the apparatus 42 is in the form of a smartphone or similar type of device, feedback regarding whether the personal care device 2 is in contact with the skin may be provided to the user or subject via an application (software application) executing on the apparatus 42. Those skilled in the art will appreciate that feedback to the user regarding whether the personal care device 2 is in contact with the skin may be provided in other ways, including, for example, using a display screen, speakers, tactile feedback, etc.

Alternatively (or additionally), in case the personal care device 2 is capable of automatically triggering a light pulse when conditions are suitable (e.g. the personal care device 2 is in contact with the skin, the skin tone of the skin with which the personal care device 2 is in contact is suitable for receiving the light pulse, etc.), the signal may be provided to the control unit of the personal care device 2, and the control unit may use the signal as a reference factor for deciding whether or not to treat the skin area currently adjacent to the aperture 10 with the energy pulse.

Accordingly, an improved system and method are provided that are capable of determining whether contact is made between the skin and a personal care device.

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. 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. A single processor or other unit may fulfill the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. 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. Any reference signs in the claims shall not be construed as limiting the scope.