System and method for determining skin contact for personal care devices

Abstract

The present disclosure relates to systems and methods for determining skin contact for personal care devices. A system configured to perform a personal care operation on a skin of a subject is provided. The system comprises a processing unit and a personal care device. The personal care device comprises a housing having an aperture arranged on the housing such that, when the personal care device is in contact with the skin and used to perform the personal care operation on the skin, the aperture is adjacent to the skin. The personal care device further comprises an imaging unit disposed within the housing and arranged to acquire an image of the skin adjacent to the aperture with 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.

Description

Technical Field

[0001] This disclosure relates to personal care devices for performing personal care procedures on the skin of a subject, and more particularly to systems and methods for determining whether a personal care device is in contact with the skin. Background Technology

[0002] Various personal care devices are used when a part of the device comes into contact with or is appropriately close to the subject's skin. Examples of these devices include those that use various techniques such as shaving, electrolysis, plucking, laser and phototherapy (known as phototherapy or intense pulsed light, IPL), and injectable anti-androgens to remove unwanted hair. Personal care devices used to reduce hair growth and treat acne also require skin contact. Personal care devices can also be used to provide massage to subjects, provide physical therapy, apply patches to subjects (such as electrocardiogram electrodes), and for ultrasound measurements.

[0003] Light-based hair removal is a personal care procedure used to inhibit hair growth by exposing the skin to bright flashes or pulses of light, known as IPL (Intense Pulsed Light), where the light pulses are generated by a lamp or bulb. Alternatively, the flashes or pulses can be generated using a laser or one or more light-emitting diodes (LEDs). The light penetrates the skin and is absorbed at the hair follicle in addition to being absorbed elsewhere. The temperature at the hair follicle rises, subsequently raising the temperature of the surrounding tissue. If the temperature rises high enough, hair growth is inhibited. This process is called photothermolysis.

[0004] For a personal care device to successfully handle and prevent potentially harmful light pulses from being directed to other parts of the body (such as the eyes), skin contact is necessary. If skin contact is not detected, the personal care device will not emit light. Therefore, a skin contact sensor can be incorporated into the personal care device to measure parameters indicating whether the device is in contact with the skin. This parameter can be capacitance or contact pressure.

[0005] Similarly, light pulses may only be applicable to certain skin types (safe only for certain skin types), and the personal care device can be prevented from emitting light if an unsafe skin tone is detected. A skin tone sensor (e.g., an optical sensor) can be incorporated into the personal care device to measure parameters (e.g., melanin index) that indicate the skin tone the device is in contact with and will be treated.

[0006] Currently, skin contact sensors and skin color sensors are integrated into the parts of personal care devices that come into contact with the skin. However, it is generally desirable for this part of the device to be detachable and interchangeable with different attachments, each suitable for different applications or body parts. For example, in the case of light-based personal care operations, different attachments could be provided for major body parts (e.g., arms, legs, bikini bottom), bikini line, face, and armpits. Currently, all attachments require both skin contact sensors and skin color sensors.

[0007] EP 3388011A1 discloses an image sensor in a processing device, and uses the sensor in a manner that addresses privacy concerns for the user and those 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 the image sensor 30 to generate skin images. Summary of the Invention

[0008] A growing number of personal care devices include imaging units (e.g., cameras) to acquire images of the subject's area to be treated with personal care procedures and the area where the procedures have already been performed. Using imaging units embedded in personal care devices can offer potential benefits, such as guiding procedures via displacement measurement and evaluating the effectiveness of personal care procedures. To minimize the cost increase of personal care devices due to the addition of imaging units and associated processing circuitry, it is worth considering whether the imaging unit can be used to perform the functions of some existing sensors in the personal care device, thus eliminating the need for these sensors. Specifically, it would be beneficial to use the imaging unit to detect skin contact instead of requiring dedicated skin contact sensors (especially where each individual accessory of the personal care device has its own skin contact sensor component).

[0009] Therefore, the object of the present invention is to provide a system and method for determining whether a personal care device is in contact with the skin using images acquired by an imaging unit.

[0010] According to a first aspect, a system configured to perform a personal care operation on the skin of a subject is provided. The system includes a processing unit and a personal care device. The personal care device includes: a housing having an aperture disposed therein, such that the aperture is adjacent to the skin when the personal care device comes into 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 the skin adjacent to the aperture using light entering the personal care device through the aperture, wherein in a skin contact detection mode of the system, the focal plane of the imaging unit is aligned with the aperture. The processing unit is configured to receive one or more images acquired by the imaging unit in the skin contact detection mode and process the one or more images to determine whether the personal care device is in contact with the skin.

[0011] In some embodiments, the imaging unit is configured such that the 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 the 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 the skin contact detection mode of the system.

[0012] 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 hole.

[0013] In some embodiments, the aperture includes a light-transmitting cover plate aligned with the aperture.

[0014] In some embodiments, the personal care device further includes a first light source disposed within the personal care device to generate skin illumination light when the imaging unit acquires one or more images.

[0015] In some embodiments, the processing unit is configured to determine whether a 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 values ​​of parameters 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 values ​​of said parameters.

[0016] In alternative embodiments, the processing unit is configured to implement a machine learning (ML) model that receives the one or more images as input and determines whether a personal care device comes into contact with the skin based on the classification of the one or more received images. In these embodiments, the ML model may be based on any of the following: support vector machines, decision trees, random forests, artificial neural networks, deep neural networks, or convolutional neural networks.

[0017] In some embodiments, the personal care device is used to perform light-based personal care operations. In these embodiments, the personal care device further includes a second light source for generating processed light to perform the light-based personal care operations.

[0018] In some embodiments, the personal care device is configured to perform personal care procedures on the skin through a hole.

[0019] In some embodiments, the system is also configured to perform a personal care operation if the processing unit determines that the personal care device is in contact with the skin, and / or to prevent the performance of a personal care operation if the processing unit determines that the personal care device is not in contact with the skin.

[0020] In an alternative embodiment, the system is also 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.

[0021] In some embodiments, the processing unit is separate from the personal care device. In an alternative embodiment, the personal care device includes the processing unit.

[0022] According to a second aspect, a method for determining whether a personal care device is in contact with skin is provided. The method includes receiving one or more images from an imaging unit in the personal care device, wherein the imaging unit is arranged to acquire one or more images using light entering the personal care device through an aperture in the housing of the personal care device, wherein, in a skin contact detection mode, the focal plane of the imaging unit is aligned with the aperture; and, in the skin contact detection mode, processing the received one or more images using a processing unit to determine whether the personal care device is in contact with skin.

[0023] In some embodiments, the imaging unit is configured such that the 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 the 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 the skin contact detection mode of the system.

[0024] In some embodiments, the processing steps include processing only the portion of the received image that corresponds to one or more edges of the hole.

[0025] In some embodiments, the aperture includes a light-transmitting cover plate aligned with the aperture.

[0026] In some embodiments, the method further includes generating skin illumination light using a first light source disposed within the personal care device when the imaging unit is to acquire one or more images.

[0027] In some embodiments, the processing steps include determining whether a personal care device is in contact with the skin based on the focus quality and / or sharpness of the image.

[0028] In these embodiments, the processing steps may include analyzing the one or more received images to determine values ​​of parameters related to focus quality and / or sharpness, and determining whether the personal care device is in contact with the skin based on the determined values ​​of the parameters.

[0029] In alternative embodiments, the processing steps include inputting one or more received images into a machine learning (ML) model, and the ML model determining whether a personal care device comes into contact with the skin based on the classification of the one or more received images. In these embodiments, the ML model may be based on any of the following: support vector machines, decision trees, random forests, artificial neural networks, deep neural networks, or convolutional neural networks.

[0030] In some embodiments, the personal care device is used to perform light-based personal care operations. In these embodiments, the personal care device further includes a second light source for generating processed light to perform the light-based personal care operations.

[0031] In some embodiments, the personal care device is configured to perform personal care procedures on the skin through a hole.

[0032] In some embodiments, the method further includes performing a personal care operation when it is determined that the personal care device is in contact with the skin, and / or preventing the performance of a personal care operation when it is determined that the personal care device is not in contact with the skin.

[0033] In an alternative embodiment, the method further includes adjusting the power consumption of the personal care device based on determining whether the personal care device is in contact with the skin.

[0034] In some embodiments, the processing unit is separate from the personal care device. In an alternative embodiment, the personal care device includes the processing unit.

[0035] According to a third aspect, a computer program product is provided, including a computer-readable medium containing computer-readable code configured to cause, when executed by a suitable computer or processor, the computer or processor to perform the method according to the second aspect or any embodiment thereof.

[0036] The above and other aspects will become apparent and clarified with reference to the embodiments described below. Attached Figure Description

[0037] An exemplary embodiment will now be described by way of example only with reference to the following figures, wherein:

[0038] Figure 1 These are illustrations of an example personal care device according to an embodiment;

[0039] Figure 2 This is a block diagram of an example system including personal care devices and apparatuses according to various embodiments;

[0040] Figure 3 yes Figure 1 A simplified cross-sectional view of an example personal care device;

[0041] Figure 4(a) shows contact with skin. Figure 3 Another cross-sectional view of a portion of the example personal care device, Figure 4(b) is an example image acquired by the imaging unit when the personal care device comes into contact with the skin;

[0042] Figure 5(a) is Figure 3 Another cross-sectional view of the non-skin-contact portion of the example personal care device, Figure 5(b) is an example image acquired by the imaging unit when the personal care device is not in contact with the skin; and

[0043] Figure 6 This is a flowchart illustrating an example method for determining whether a personal care device comes into contact with the skin. Detailed Implementation

[0044] Figure 1 This is an illustration of an example personal care device 2 according to an embodiment, which can be used to apply energy pulses (e.g., light pulses) to a skin area. It should be understood that... Figure 1 The personal care device 2 described herein is merely an example of a personal care device 2 that can be used in this invention, and the personal care device 2 is not limited to... Figure 1 The form shown may not be limited to energy-based personal care devices. In some embodiments, the personal care device 2 is held by a user in one or both hands during use. The personal care device 2 is used on the body of a subject (e.g., a person or animal), and when the personal care device 2 comes into contact with the subject's skin, it performs some personal care procedures on the subject's body. In some embodiments, the personal care device 2 will perform some personal care procedures on the subject's skin. Some example personal care procedures include, but are not limited to, removing unwanted hair by any of shaving, electrolysis, laser, and phototherapy (known as phototherapy or intense pulsed light); dermatological (skin) treatments, including reducing hair growth, treating acne, phototherapy treatments, skin regeneration, skin tightening, or port-wine stain treatment; and pain relief.

[0045] As described herein, the personal care device 2 is operated or used by a “user” and is applied to 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 their hand and uses it themselves (e.g., on the skin of their leg). In other cases, the user and the subject are different people, e.g., the user holds the personal care device 2 in their hand and uses it on someone else.

[0046] The personal care device 2 includes a housing 4, which includes at least a handle portion 5 and a body portion 6. The handle portion 5 is shaped to allow a user to hold the personal care device 2 with one hand. The body portion 6 has a first end 8, which is positioned to contact the subject's skin when a personal care procedure is to be performed on the subject's body or skin.

[0047] exist Figure 1 In the illustrated embodiment, the personal care device 2 is used to perform personal care operations using energy or energy pulses (e.g., light or light pulses). Therefore, in Figure 1 In the first end 8, the housing 4 includes a hole 10 disposed in or on the housing 4, such that the hole 10 can be placed on or near the skin of a subject (i.e., in contact with the subject's skin). The personal care device 2 includes one or more energy sources 12 disposed within the housing 4 for generating energy pulses that are applied to the subject's skin via the hole 10 to perform personal care operations. The one or more energy sources 12 are disposed within the housing 4 such that energy pulses are provided from the one or more energy sources 12 through the hole 10. The hole 10 may be in the form of an opening at the first end 8 of the housing 4. In some embodiments, the hole 10 includes a transparent (e.g., light-transmitting) hole cover 14 through which energy pulses can pass (i.e., energy pulses can pass through the hole cover 14).

[0048] exist Figure 1 In the example embodiment shown, the hole 10 and the hole cover 14 (if present) have a generally rectangular shape, which forms a generally rectangular skin treatment area on the skin. It should be understood that the hole 10 and / or the hole cover 14 can have any other desired shape. For example, the hole 10 and / or the hole cover 14 can be square, elliptical, circular, or any other polygon.

[0049] One or more energy sources 12 can generate any suitable type of energy for performing personal care procedures, such as light, sound, radio frequency (RF) signals, microwave radiation, and plasma. In the case of energy sources 12 generating light, the energy source 12 can be configured to generate light pulses of any suitable or desired wavelength (or wavelength range) and / or intensity. For example, energy source 12 can generate visible light, infrared (IR) light, and / or ultraviolet (UV) light. Each energy source 12 can include any suitable type of light source, such as one or more light-emitting diodes (LEDs), flashlights (e.g., xenon flashlights), one or more lasers, etc. In a preferred embodiment, the personal care device 2 is used to perform phototherapy hair removal, and energy source 12 is used to provide intense light pulses. For example, energy source 12 can provide light pulses with a spectral content in the range of 560-1200 nanometers (nm) and a duration of approximately 2.5 milliseconds (ms), because these wavelengths heat the melanin in the hair and hair root through absorption, which puts the hair follicle into a dormant phase and prevents hair regrowth. In the case of an energy source 12 for generating sound, the energy source 12 can be configured to generate sound pulses at any suitable or desired wavelength (or wavelength range) and / or intensity. For example, the energy source 12 can be an ultrasonic transducer.

[0050] 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 very short duration (e.g., less than 1 second). The intensity of the energy pulse should be high enough to enable personal care procedures on the skin or body part adjacent to the orifice 10.

[0051] The illustrated personal care device 2 also includes a user controller 16, which a user can operate to activate the personal care device 2, thereby performing desired personal care procedures on the subject's body (e.g., generating energy pulses from one or more energy sources 12). The user controller 16 may be in the form of a switch, button, touchpad, etc.

[0052] Although Figure 1 Not shown, but the first end 8 can be molded as a detachable attachment for a specific body part. The detachable attachment is also referred to herein as a detachable head portion. Multiple detachable attachments can be provided, each with its own shape and hole size, and the attachment can be selected for the personal care device 2 based on the body part to be treated. For example, different attachments can be provided for the face, armpits, bikini line, and generally for the body (e.g., larger body surface areas). Each attachment has its own hole 10 and an optical diffuser 14 located in / on the hole 10.

[0053] Although Figure 1Not shown, but the personal care device 2 may include a skin color sensor located on or within the first end 8. The skin color sensor can be used to determine the skin color of the skin adjacent to or in contact with the first end 8. The skin color sensor can measure parameters indicating skin color and generate a time series including measurement signals of those parameters. Typically, the personal care device 2 uses a skin color sensor (particularly a photomask) to ensure that the light pulses have an intensity suitable for the skin type being treated, or even to prevent the generation of light pulses when the skin type is unsuitable for them (e.g., darker skin with a much higher melanin content).

[0054] A skin color sensor can be a light sensor, and the parameter measured by the light sensor can be the intensity or level of light of a specific wavelength or multiple wavelengths reflected from the skin. The measured intensity or level of reflected light at a specific wavelength can indicate skin color. The measured intensity or level of reflected light can be based on the concentration of melanin in the skin, thus the measured intensity or level can indicate melanin concentration. Melanin concentration can be obtained by measuring light reflection at wavelengths such as 660 nm (red) and 880 nm (infrared).

[0055] As described above, conventional personal care devices may include dedicated sensors for detecting when or whether the personal care device comes into contact with the skin. In the case of personal care devices, particularly photosensitive hair removal devices, skin contact sensors are used to ensure that the personal care device properly contacts the skin before generating light pulses to prevent the light pulses from being directed into the user's or subject's eyes. Typically, these dedicated sensors can detect skin contact by measuring capacitance via a corresponding pair of electrical contacts or electrodes on a first end surface; the measured capacitance indicates the presence of skin contact. Alternatively, these dedicated sensors can detect skin contact based on the intensity or level of light measured by a light sensor, or by measuring contact pressure via a pressure sensor or mechanical switch. Because these dedicated skin contact sensors are typically integrated into the skin-contacting part of the personal care device, and this part of the device is interchangeable with different accessories, skin contact sensors are required on all accessories.

[0056] Therefore, this disclosure provides a method for detecting contact between a personal care device and skin using images acquired by one or more imaging units disposed within a housing of a personal care device. This means that a separate skin contact sensor is not required on the personal care device (and not on different accessories). Thus, as further described below, one or more imaging units are disposed within the housing 4 and arranged to acquire images of skin adjacent to the aperture 10 using light entering the personal care device 2 through the aperture 10 (or, in the case of multiple imaging units, through corresponding apertures). The one or more images acquired by the imaging units are provided to a processing unit, which 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 device 2 includes a single imaging unit that acquires an image using light entering the personal care device 2 through the aperture 10. However, in other embodiments, the personal care device 2 may include multiple imaging units. These multiple imaging units may be arranged to image through corresponding portions of the aperture 10, such as corresponding portions around the edge of the aperture 10, or a corresponding aperture may be provided on the housing 4 for each imaging unit. 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 device 2 comprising a single imaging unit, these embodiments can be readily adapted to a personal care device 2 using multiple imaging units, and further details of embodiments with multiple imaging units are not described herein.

[0057] Figure 2 This is a block diagram of an example system 40 including a personal care device 2 and a device 42 for determining whether the personal care device 2 comes into contact with the skin. Figure 2 In this embodiment, device 42 is a device independent of personal care device 2; therefore, device 42 can be in the form of an electronic device, such as a smartphone, smartwatch, tablet computer, personal digital assistant (PDA), laptop computer, desktop computer, remote server, smart mirror, etc. In other embodiments, device 42 (specifically, the functionality provided by device 42) is part of personal care device 2. In other embodiments, the functionality of device 42 described below can be distributed between personal care device 2 and separate device 42.

[0058] The personal care device 2 includes an imaging unit 44 for acquiring an image of the skin adjacent to the hole 10 using light that enters the personal care device 2 through the hole 10. Figure 2Only the imaging unit 44 of the personal care device 2 is shown, and it should be understood that in practice, the personal care device 2 includes other components besides those shown, such as the energy source 12, power supply, control unit, etc. In some embodiments, as further described below, one or more light sources may be provided, which are associated with the imaging unit 44 and are used to generate light when the imaging unit 44 wants 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 should be understood that this light illuminates the skin only when the skin is in contact with or near the personal care device 2. Figure 2 The light source is not shown in the diagram. Imaging unit 44 may include any suitable components for capturing images, multiple 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.

[0059] The device 42 includes a processing unit 46, which generally controls the operation of the device 42 and enables the 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.

[0060] Therefore, the processing unit 46 can be configured to receive images directly from the imaging unit 44 in embodiments where the device 42 is part of the personal care device 2, or via another component in embodiments where the personal care device 2 is separate from the device 42. In either case, the processing unit 46 may include or contain one or more input ports or wires 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 wires for outputting signals indicating whether the personal care device 2 is in contact with the skin.

[0061] Processing unit 46 may be implemented in a variety of ways, through software and / or hardware, to perform the various functions described herein. Processing unit 46 may include one or more microprocessors or digital signal processors (DSPs) that can be programmed using software or computer program code to perform desired functions and / or control components of processing unit 46 to achieve those functions. Processing unit 46 may be implemented as a combination of dedicated hardware performing some functions (e.g., amplifiers, preamplifiers, analog-to-digital converters (ADCs) and / or digital-to-analog converters (DACs)) and processors performing other functions (e.g., one or more programmed microprocessors, controllers, DSPs, and associated circuitry). Examples of components that may be employed in various embodiments of this disclosure include, but are not limited to, conventional microprocessors, DSPs, application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), hardware for implementing neural networks, and / or so-called artificial intelligence (AI) hardware accelerators (i.e., processors or other hardware specifically designed for AI applications that can be used in conjunction with a main processor).

[0062] Processing unit 46 may include or be associated with memory unit 48. Memory unit 48 may store data, information, and / or signals (including images) for use by processing unit 46 in the operation of control device 42 and / or in performing or implementing the methods described herein. In some embodiments, memory unit 48 stores computer-readable code 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 for a smartphone, tablet, laptop, computer, or server. Memory cell 48 may include any type of non-transitory machine-readable medium, such as 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 the memory cell may be implemented as a memory chip, optical disc (e.g., compact disc (CD), digital versatile disc (DVD), or Blu-ray disc), hard disk, magnetic tape storage solution, or solid-state device, including memory stick, solid-state drive (SSD), memory card, etc.

[0063] exist Figure 2In the illustrated embodiment, since a device 42 separate from the personal care device 2 / imaging unit 44 is shown, device 42 also includes interface circuitry 50 to enable device 42 to receive images from imaging unit 44. Interface circuitry 50 in device 42 is capable of performing data connections and / or data exchange with other devices, including any one or more of imaging unit 44, personal care device 2, servers, databases, user devices, and sensors. Direct or indirect connections (e.g., via the Internet) can be established with imaging unit 44 (or any electronic device, such as processing device 2), so interface circuitry 50 can enable device 42 to connect to a network via any desired wired or wireless communication protocol, or to enable direct connection between device 42 and another device (e.g., imaging unit 44 and / or personal care device 2). For example, interface circuitry 50 can 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 wireless connectivity, interface circuitry 50 (and therefore 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 wireless connectivity, interface circuitry 50 may include mechanisms (e.g., connectors or plugs) that enable interface circuitry 50 to connect to one or more suitable antennas external to device 42 for performing transmission / reception over a transmission medium (e.g., air). Interface circuitry 50 is connected to processing unit 46.

[0064] Despite Figure 2 Although not shown, device 42 may include one or more user interface components, which include components that enable a user of device 42 to input information, data, and / or commands into device 42, and / or enable device 42 to output information or data to the user of device 42. The user interface may include any suitable input components, including but not limited to a keyboard, keypad, one or more buttons, switches or dial pads, mouse, trackpad, touchscreen, stylus, camera, microphone, etc. The user interface may also include any suitable output components, including but not limited to a display unit or display screen, one or more lamps or lamp elements, one or more speakers, vibration elements, etc. In some embodiments, the user interface components may be used to provide the user with indications regarding whether the personal care device 2 is in contact with the skin or whether it is in proper contact with the skin. This indication may be determined based on the processing results of the image by processing unit 46. In embodiments, this indication may be provided as a visual indication, an auditory indication, and / or a tactile indication.

[0065] It should be understood that the actual implementation of device 42 may include, except for Figure 2Additional components beyond those shown. For example, device 42 may also include a power source, such as a battery, or components for enabling device 42 to be connected to a main power source.

[0066] Figure 3 yes Figure 1 A simplified cross-sectional view of the example personal care device 2 shows the arrangement of the imaging unit 44 within the personal care device 2. In this embodiment, the device 42, particularly 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 device 2 through the aperture 10. A user interface component 52 connected to the processing unit 46 is also shown, and this user interface component 52 can be used to provide feedback to the user of the personal care device 2 based on the processing results of the images by the processing unit 46.

[0067] Figure 3 One or more light sources 54 are also shown, associated with the imaging unit 44 and used to generate light when the imaging unit 44 wants to acquire an image. When the aperture 10 is positioned against the skin, the imaging unit 44 may have difficulty acquiring a good image of the skin due to low light conditions. Therefore, the light sources 54 are arranged within the housing 4 such that the light generated by the light sources 54 can pass through the aperture 10 (and the aperture cover 14, if present) to illuminate any subject (including skin) near or in contact with the aperture 10. The one or more light sources 54 can be LEDs or any other suitable type of light source. The one or more light sources 54 can emit white light (or combine to provide the color of white light (e.g., RGB)), light of a specific color, light with a specific spectral content, or infrared light. Illuminating the skin with different colors of light allows the images acquired by the imaging unit 44 to include color information, which can then be used to determine skin color and skin contact. As another example, illuminating the skin with infrared light allows the skin's melanin index to be determined. Typically, these one or more light sources 54 are different from any light source 12 used to perform personal care procedures.

[0068] Figure 4(a) is Figure 3Another cross-sectional view of a portion of the example personal care device in contact with skin 55. Figure 4(a) shows a portion of the main body 6 including imaging unit 44. Two components of imaging unit 44 are also shown, namely image sensor 60 and optical focusing assembly 62, in this embodiment, optical focusing assembly 62 including a single lens 64. Image sensor 60, such as a charge-coupled device (CCD), senses incident light and outputs an image signal (to processing unit 46) including information about or representing the incident light. Optical focusing assembly 62 is located in front of image sensor 60 for focusing incident light onto image sensor 60. It should be understood that although only one lens 64 is shown in optical focusing assembly 62, a typical optical focusing assembly 62 may include more than one lens 64.

[0069] According to the technique described herein, skin contact detection is based on whether the skin image acquired by imaging unit 44 is in focus or sharp. That is, if the acquired image includes focused skin, processing unit 46 can determine that personal care device 2 is in contact with skin, and if the acquired image does not include skin, or does not include focused skin, processing unit 46 can determine that personal care device 2 is not in contact with skin (or is not in proper contact with skin). To achieve this, imaging unit 44 (specifically, optical focusing assembly 62) is configured such that, at least during the skin contact detection mode of system 40, the focal plane 66 of imaging unit 44 is aligned with aperture 10. As understood by those skilled in the art, the focal plane of lens 64, or more generally, the focal plane of optical focusing assembly 62, is a plane perpendicular to the optical axis of lens 64 / optical focusing assembly 62, which coincides with the focal point in front of lens 64 / optical focusing assembly 62. Thus, when the personal care device 2 comes into contact with the skin 55, as shown in Figure 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 focused. In Figure 4(a), various distances are labeled: image distance d... i (Distance between lens 64 and image sensor 60), object distance d o (The distance between lens 64 and aperture 10) and the focal length l of lens 64 f .

[0070] To improve the detection of personal care device 2 not contacting or not properly contacting skin 55, imaging unit 44 can be configured such that its depth of field is narrow or small. As understood by those skilled in the art, the depth of field of lens 64 / optical focusing assembly 62 is the distance between the nearest and farthest points from lens 64 / optical focusing assembly 62 when the imaged subject is focused. Depth of field is denoted by d. fThis is indicated, and shown by dashed line 68 in Figure 4(a). The depth of field 68 is preferably narrow 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., properly in terms of performing 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 can be in the range of 2-3 millimeters (mm). Therefore, if the distance between the skin 55 and the aperture 10 of the personal care device 2 is greater than 1-2 mm, the skin 55 will not be fully in focus in the acquired image.

[0071] Figure 4(b) is an example image 70 acquired by the imaging unit 44 in the personal care device 2 when the personal care device 2 comes into contact with the skin 55. Skin elements (such as various hairs on the skin) in image 70 are focused and visible.

[0072] Figure 5(a) shows the personal care device 2 of Figure 4(a) spaced a short distance from the skin 55. At least during the skin contact detection mode of the system 40, where 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. This means that when the personal care device 2 is in this position, the image of the skin 55 acquired will be out of focus. Figure 5(b) is an example image 72 of the same area of ​​the skin 55 as in Figure 4(b), acquired by the imaging unit 44 in the personal care device 2 when the personal care device 2 is spaced apart from the skin 55 as shown in Figure 5(a). In Figure 5(b), the skin elements in image 70 can be seen to be out of focus or not clearly visible.

[0073] As described above, the imaging unit 44 (particularly the optical focusing assembly 62) is configured such that the focal plane 66 of the imaging unit 44 is aligned with the aperture 10, at least during the skin contact detection mode where skin contact is to be detected. In some embodiments, the focal plane 66 of the imaging unit 44 / optical focusing assembly 62 is in a fixed position relative to the aperture 10, and in particular, the focal plane is fixed at the aperture 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).

[0074] However, in alternative embodiments, the imaging unit 44 / optical focusing assembly 62 can be configured such that when the system 40 is not operating in skin contact detection mode, the focus of the imaging unit 44 / optical focusing assembly 62 is variable or adjustable to enable the acquisition of focused images of subjects not in contact with the personal care device 2 / hole 10. This may be ideal if the images acquired by the imaging unit 44 can 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 the personal care device 2 is used on the body. In these embodiments, when skin contact is to be detected (i.e., the system 40 is operating in 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 hole 10 to enable the acquisition of focused images of the skin when the personal care device 2 is in contact with the skin.

[0075] exist Figure 1 , 3 In the embodiments shown in 4(a) and 5(a), the imaging unit 44 and the energy source 12 share the same aperture 10 and aperture cover 14 (if present). That is, the imaging unit 44 generates an image from light entering the personal care device 2 through the aperture 10, and the energy source 12 emits energy out of the personal care device 2 through the aperture 10. However, in an alternative embodiment, the personal care device 2 may be provided with a first aperture that can be used to detect contact with the skin (i.e., the imaging unit 44 can generate an image from light entering the personal care device 2 through the first aperture), and a second aperture (e.g., aperture 10) that can be used for personal care operations (i.e., energy from the energy source 12 leaves the personal care device 2 through the second aperture).

[0076] although Figure 1 , 3 The embodiments of the personal care device 2 shown in 4(a) and 5(a) are designed for performing personal care operations using energy or energy pulses (e.g., light or light pulses), but it should be understood that the personal care device 2 can be designed for performing other types of operations. For example, the personal care device 2 can be a razor or hair clipper, in which case the body portion 6 can include one or more cutting blades or foils for cutting hair when the body portion 6 comes into contact with the skin. As another example, the personal care device 2 can be an ultrasound probe for acquiring ultrasound images. In this example, the body portion 6 can include an ultrasound transducer for generating ultrasound waves and an ultrasound receiver for receiving ultrasound waves reflected from inside the body. In these alternative types of personal care devices where the personal care operation is not performed via a hole in the housing 4, the personal care device 2 has a hole 10 at the location where it comes into contact with the skin when the personal care device 2 is in place to perform the personal care operation, allowing the imaging unit to acquire an image of the skin via the hole 10. The hole 10 can include a hole cover 12 as described above.

[0077] In embodiments where the personal care device 2 does not include the orifice cover 14, the skin adjacent to the orifice 10 may "bulge" or "protrude" when the personal care device 2 comes into contact with the skin. Specifically, if the personal care device 2 is pressed against the skin, the edge of the orifice 10 will press down on the skin surface, which may cause the skin to "bulge" or "protrude" in the middle of the orifice 10 (i.e., the skin extends a short distance into the orifice 10 towards the center). In this case, since the focal plane of the imaging unit 44 is aligned with the orifice 10, the processing unit 46 is configured to process the image portion around the edge of the orifice 10 in the image, because in these portions of the image, the skin will be in focus when the personal care device 2 is in contact with the skin. Therefore, in these embodiments, when detecting whether there is skin contact, the processing unit 46 may ignore the central portion of the acquired image where the skin may have "bulged" into the orifice 10 and may be outside the depth of field 68 of the imaging unit 44.

[0078] In embodiments where the aperture 10 includes an aperture cover 14, the plane of the aperture cover 14 is preferably aligned with the plane of the aperture 10. In this way, the aperture cover 14 will prevent skin adjacent to the aperture 10 from "bulging" 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.

[0079] In embodiments where the personal care device 2 is used to perform personal care operations, skin contact is required to ensure the safety of the user and / or subject. For example, if the personal care device 2 is a phototherapy hair removal device or other light-based personal care device, the triggering or initiation of 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.

[0080] In other embodiments, skin contact detection can be used to regulate the power consumption of the personal care device 2. Specifically, if skin contact is detected, the personal care device 2 can perform a personal care operation, while if no skin contact is detected, the personal care operation cannot be performed properly, and the personal care device 2 can be disabled or placed in a low-power mode. For example, in the case where the personal care device 2 includes a mechanical cutting element or a mechanical shaving element for cutting or shaving hair, when skin contact is detected, the cutting or shaving element can be activated so that hair can be cut, but when no skin contact is detected (or when the personal care device 2 is not in contact with the skin), the cutting or shaving element can be disabled, or the cutting speed (e.g., motor speed) of the cutting or shaving element can be reduced.

[0081] As described above, when it is necessary to determine whether the personal care device 2 is in contact with the skin (e.g., at the moment before a personal care procedure is to be performed), the imaging unit 44 acquires one or more images and provides them to the processing unit 46. The processing unit 46 processes the images to determine whether the personal care device 2 is in contact with the skin. In some embodiments, particularly where skin contact detection involves safety aspects, the processing unit 46 may provide an indication of whether the personal care device 2 is in contact with the skin for each received image.

[0082] In some embodiments, processing unit 46 analyzes the entire acquired image to determine if there is skin contact; however, in other embodiments, processing unit 46 may crop the acquired image or otherwise analyze only a portion of the acquired image. For example, the latter case may be adopted, where the hole 10 does not include the hole cover 14, and the skin bulges or protrudes into the hole 10 when the personal care device 2 is pressed against the skin. Therefore, processing unit 46 may crop the acquired image or analyze only the outer portion of the image corresponding to the edge of the hole 10, where the bulge or protrusion is minimal. On the other hand, if the hole cover 14 is present, processing unit 46 may crop the acquired image or otherwise analyze only the inner portion of the image corresponding to the center of the hole 10, where the light source associated with imaging unit 44 can illuminate the skin more uniformly.

[0083] In some embodiments, 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. Image sharpness relates to the sharpness of visible feature edges in the image. For an image, if the image is out of focus / blurred and / or unclear, processing unit 46 may determine that there is no skin contact, while if the image is in focus and / or sharp, processing unit 46 may determine that there is skin contact. In these embodiments, processing unit 46 may analyze the image to determine parameter values ​​related to focus quality (e.g., a measure of the degree of image focus) and / or sharpness (and optional other image-related parameters, such as brightness, contrast, parameters related to the presence of skin features in the image, etc.), and compare these values ​​with one or more thresholds or ranges related to the presence / absence of skin contact to determine whether skin contact is present. 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 those described in “Analysis of focus measure operators for shape-from-focus”, Pattern Recognition, 46.5 (2013): 1415-1432, by Pertuz, Said, Domenec Puig and Miguel Angel Garci.

[0084] In an alternative embodiment, processing unit 46 may use or implement a trained machine learning (ML) model to analyze the image to determine whether 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 the presence of skin contact. For other types of ML models, processing unit 46 may determine parameter values ​​(and optionally other image-related parameters) related to focus / focus quality and / or sharpness, and input these parameter values ​​into the ML model. The ML model uses the input parameter values ​​to determine whether skin contact is present and outputs a signal indicating the presence of skin contact. Some types of ML models that may be used include classic machine learning models, such as those utilizing feature extraction performed by support vector machines, decision trees, random forests, etc., or artificial neural networks, such as deep neural networks or convolutional neural networks, which have multiple layers between input and output layers and identify linear or non-linear relationships between input and output layers.

[0085] In some embodiments, before deploying the ML model in the personal care device 2, the ML model is first trained, for example, using training data including skin images from a group of subjects. In this case, the training data may include multiple 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 multiple images acquired when the personal care device 2 is known to be in contact with different parts 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 controlled user testing before deploying 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 annotations for the presence / absence of skin contact for those images. Optionally, the training data may also include images of other subjects or background visible to the imaging unit 44 during use of the personal care device 2. The training data is used, for example, to train the ML model using a supervised ML method. This training method generates a deployable training classifier algorithm that outputs "skin contact present" or "skin contact absent" based on one or more input images.

[0086] In other embodiments, the ML model can be trained during an initial calibration process performed when a user or subject first uses the personal care device 2. In this case, the user can be instructed to collect training data for the ML model by having the imaging unit 44 acquire multiple images when it is known that the personal care device 2 is not in contact with the skin, and by having the imaging unit 44 acquire multiple 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 can be used; that is, the ML model can be trained prior to deployment, and a calibration process can be performed to refine the ML model for the specific skin characteristics of the subject.

[0087] Figure 6 The flowchart illustrates an example method for determining whether a personal care device 2 has come into contact with skin, according to the techniques described herein. One or more steps of this method may be performed by system 40 (e.g., processing unit 46 in device 42) in conjunction with any of the memory unit 48 and interface circuitry 50 of device 42 and / or imaging unit 44, as appropriate. Processing unit 46 may perform one or more steps in response to executing computer program code that may be stored on a computer-readable medium (e.g., memory unit 48).

[0088] although Figure 6As not shown, the initial steps of this method (when system 40 is operating in skin detection mode) may include imaging unit 44 acquiring (generating) one or more images. When acquiring one or more images, the focal plane of imaging unit 44 is aligned with the aperture 10 of personal care device 2.

[0089] In step 101, one or more images are received from imaging unit 44. When imaging unit 44 generates an image, the image can be received directly from imaging unit 44, for example, in real-time or near real-time. Alternatively, images can be received from imaging unit 44 in a separate personal care device 2 via interface circuitry 50. As described above, imaging unit 44 is arranged to acquire one or more images using light entering personal care device 2 through aperture 10. At least when system 40 is operating in skin contact detection mode, the focal plane of imaging unit 44 is aligned with aperture 10. In the case of imaging unit 44 with a non-adjustable focal plane, the focal plane of imaging unit 44 will be aligned with aperture 10 even when system 40 is not operating in skin contact detection mode. In the case of imaging unit 44 with an adjustable focal plane, the focal plane of imaging unit 44 can still be aligned with aperture 10 even when system 40 is not operating in skin contact detection mode.

[0090] In step 103, the processing unit 46 processes one or more images (when the system 40 is operating in skin contact detection mode) to determine whether the personal care device 2 is in contact with the skin.

[0091] In some embodiments of step 103, thanks to the arrangement of the focal plane of the imaging unit 44 when the system 40 operates in skin contact detection mode, the processing unit 46 can process the image to determine whether the image is in focus and / or sharp. In some embodiments, if the processing unit 46 determines that the image is out of focus or blurry, the processing unit 46 can 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 in focus and / or sharp, the processing unit 46 can determine that the personal care device 2 is in contact with the skin.

[0092] In some embodiments of step 103, a trained ML model is used to process one or more images to determine whether the personal care device 2 is in contact with the skin. The ML model may perform evaluation or classification on each image to determine whether the personal care device 2 is in contact with the skin. In some embodiments, the ML model directly receives the images and performs all necessary analysis and processing on the images to determine whether contact exists between the personal care device 2 and the skin. This is particularly true for ML models using artificial neural networks (e.g., deep neural networks). In other embodiments, such as when using a classic ML model, the images may be processed before being fed to the ML model, for example, determining the values ​​of one or more features associated with the image, and (optionally, in addition to the image) these values ​​may also be fed to the ML model to perform analysis to determine whether the personal care device 2 is in contact with the skin.

[0093] Then, despite Figure 6 Although not shown, it can output a signal indicating whether the personal care device is in contact with the skin. In some embodiments, the indication may be simply "skin contact present" or "skin contact absent".

[0094] This signal can be provided to the user interface component of device 42 or personal care device 2, and is configured to cause the user interface component to indicate whether personal care device 2 is in contact with the skin. For example, if it is determined that personal care device 2 is not in contact with the skin, the signal can cause a red light on personal care device 2 to illuminate. Similarly, if it is determined that personal care device 2 is in contact with the skin, the signal can cause a green light on personal care device 2 to illuminate. The user of personal care device 2 will be able to use these indications to determine whether a personal care operation is triggered at the current location of personal care device 2. As another example, if device 42 is in the form of a smartphone or a similar type of device, feedback on whether personal care device 2 is in contact with the skin can be provided to the user or subject via an application (software application) running on device 42. Those skilled in the art will recognize that feedback on whether personal care device 2 is in contact with the skin can be provided to the user in other ways, such as by using a display screen, a speaker, haptic feedback, etc.

[0095] Alternatively (or additionally), if the personal care device 2 can automatically trigger a light pulse when conditions are suitable (e.g., the personal care device 2 is in contact with the skin, the skin color of the skin in contact with the personal care device 2 is suitable for receiving light pulses, etc.), the signal can be provided to the control unit of the personal care device 2, and the control unit can use the signal as a reference factor in deciding whether to use energy pulses to treat the skin area of ​​the current adjacent hole 10.

[0096] Therefore, an improved system and method are provided to determine whether there is contact between the skin and a personal care device.

[0097] By studying the accompanying drawings, the disclosure, and the appended claims, those skilled in the art can understand and implement variations of the disclosed embodiments in practice with respect to the principles and techniques described herein. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite articles "a" or "an" do not exclude multiple. A single processor or other unit can perform the functions of several items described in the claims. Reference to certain measures in mutually different dependent claims does not imply that combinations of these measures cannot be advantageously used. Computer programs may be stored or distributed on suitable media, such as optical storage media or solid-state media provided 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 telecommunications systems. No reference numerals in the claims should be construed as limiting the scope.

Claims

1. A system (40) configured to perform personal care procedures on the skin of a subject, the system (40) comprising: Processing unit (46); as well as Personal care equipment (2), including: The housing (4) has a hole (10) arranged in the housing (4) such that when the personal care device (2) comes into contact with the skin and is to be used to perform a personal care operation on the skin, the hole (10) is adjacent to the skin; An imaging unit (44) is disposed within the housing (4) and is arranged to acquire an image of the skin adjacent to the hole (10); The personal care device (2) includes a first light source arranged in the housing (4) and adapted to generate light to illuminate the skin through a hole (10); The imaging unit (44) is arranged to acquire an image of the skin adjacent to the hole (10) using light passing through the hole (10) and entering the personal care device (2), wherein in the skin contact detection mode of the system (40), the focal plane (66) of the imaging unit (44) is aligned with the hole (10); and The processing unit (46) is configured to receive one or more images acquired by the imaging unit (44) in the skin contact detection mode, and to process one or more of the 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 aperture (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 3, wherein the hole (10) comprises a light-transmitting cover plate (14) aligned with the hole (10).

6. The system (40) according to any one of claims 1 to 3, wherein the processing unit (46) is configured to determine whether the personal care device (2) is in contact with the skin based on the focus quality and / or sharpness of the image.

7. The system (40) of claim 6, wherein the processing unit (46) is configured to analyze one or more of the received images to determine the values ​​of parameters 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 values ​​of the parameters.

8. The system (40) according to any one of claims 1 to 3, wherein the processing unit (46) is configured to implement a machine learning (ML) model that receives one or more of the images as input and determines whether the personal care device (2) is in contact with the skin based on the classification of the one or more of the received images.

9. The system (40) according to any one of claims 1 to 3, wherein the personal care device (2) further comprises a second light source for generating processed light to perform the light-based personal care operation.

10. The system (40) according to any one of claims 1 to 3, wherein the personal care device (2) is configured to perform personal care operations on the skin through the orifice (10).

11. The system (40) according to any one of claims 1 to 3, wherein the system (40) is further configured to: perform the personal care operation when the processing unit (46) determines that the personal care device (2) is in contact with the skin, and / or prevent the performance of the personal care operation when the processing unit (46) determines that the personal care device (2) is not in contact with the skin.

12. The system (40) according to any one of claims 1 to 3, wherein the system (40) is further configured to adjust the 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.

13. A method for determining whether a personal care device comes into contact with skin, wherein the personal care device (2) includes a housing (4) having an aperture (10) disposed therein such that when the personal care device (2) comes into contact with the skin, the aperture (10) is adjacent to the skin, the method comprising: Receive one or more images from the imaging unit in the personal care device; Light is generated by a first light source disposed within the housing (4) and passes through the hole (10) to irradiate the skin; In skin contact detection mode, the focal plane of the imaging unit is aligned with the aperture, wherein the imaging unit is arranged to acquire the one or more images using light that passes through the aperture in the housing of the personal care device and enters the personal care device; as well as In the skin contact detection mode, a processing unit is used to process one or more of the received images to determine whether the personal care device is in contact with the skin.

14. A computer program product comprising a computer-readable medium containing computer-readable code implemented therein, the computer-readable code being configured to cause the computer or processor, when executed by a suitable computer or processor, to perform the method of claim 13.

Images