Optical treatment device

Abstract

A treatment device 2,100 for performing a light-based treatment operation on or against a target is provided, comprising: a light source 12,101 configured to generate light pulses, the light source 12,101 including a housing, a gas in the housing, and two internal electrodes 130 within the housing; a plasma ignition unit 108 configured to apply a first voltage between the light source 12,101 and a first external electrode 102 outside the housing to initiate plasma breakdown of the gas in the light source 12,101; a capacitor 132 configured to store electrical energy and apply the stored electrical energy to the two internal electrodes 130 to generate a light pulse when plasma breakdown of the gas is initiated; and a second external electrode 106 outside the housing and connected to electrical earth, the second external electrode 106 being spaced apart from the first external electrode 102 such that when the first voltage is applied the first voltage at the first external electrode 102 discharges through the second external electrode 106.

Description

Technical Field

[0001] The present disclosure relates to a treatment device for performing a light-based treatment operation on or with respect to a subject.

Background Art

[0002] Techniques for removing unwanted hair include shaving, electrolysis, epilation, laser and light therapy (known as photoepilation), and therapeutic androgen injections. Light-based techniques are also used for other types of dermatological treatments, including hair growth reduction and acne treatment.

[0003] Light-based hair treatment inhibits hair growth by exposing the skin to bright flashes or pulses of light known as intense pulsed light (IPL). Through the use of an appropriate configuration of light energy, namely wavelength, intensity and / or pulse duration (if the light is pulsed), selective heating of the hair follicles and subsequent temporary or permanent damage to the hair follicles can be achieved. IPL can be generated by a high-intensity light source such as a gas discharge lamp (e.g., a xenon flash lamp). The light penetrates the skin and is absorbed at the hair follicles, particularly by the melanin pigment. This causes the temperature of the hair follicles to rise, subsequently causing the temperature of the surrounding tissue to rise. The heat generated damages the hair follicles and inhibits hair growth if the temperature rise is sufficient. This process is known as photothermolysis.

[0004] Light-based hair removal can be performed using commercially available "home use" devices (consumer devices suitable for use by non-experts), such as the Lumea device from Philips. Home use devices typically use IPL technology at a relatively low fluence (e.g., up to 6.5 J / cm2) compared to professional devices that use a fluence exceeding 10 J / cm2. Long-lasting hair reduction is achieved when the treatment is repeated at intervals of two to four weeks.

[0005] Figure 1 is a schematic diagram showing a part of the elements of the IPL treatment device 100. The device 100 has a gas discharge lamp 101 that generates intense light pulses (also called flashes in this document), and a light reflector 102 positioned to direct the light pulses towards the target skin 103. The gas discharge lamp 101 has a gas inside a housing, for example, a glass tube. The gas is typically a noble gas such as xenon or argon, or a mixture of such gases. The flash is generated by applying a voltage across the gas to cause a discharge. The voltage can be applied, for example, via internal electrodes 130 inside both ends of the glass tube. The internal electrodes 130 are connected to one or more capacitors 132 (outside the glass tube) that store the electrical energy required for the voltage applied across the internal electrodes 130. In most cases, an ignition voltage (known as a trigger) is first required to (partially) ionize the gas inside the lamp before the main electrical pulse initiates the main discharge that generates the flash. The partial ionization of the gas is called plasma breakdown. In some cases, the ignition voltage can be applied between an electrode of the lamp (typically one of the two internal electrodes 130) and an additional external electrode (known as an external trigger) outside the glass tube. The additional external electrode (also called the ignition electrode or "first external electrode" in this document) can be any conductive element, for example, a metal element. In the example shown in Figure 1, the reflector 102, which is a metal element, is used as the additional external electrode. As a result, the ignition voltage is applied between the electrode of the lamp 101 and the reflector 102. In another example, the additional external electrode can be a metal element wound around the glass tube. The metal element can be in the form of a wire or a strip. In Figure 1, the ignition voltage between the lamp 101 and the reflector 102 is generated by a plasma ignition unit 108.

[0006] Treatment device 100 can include various sensors (not shown in FIG. 1). For example, standard devices currently on the market typically include a skin contact sensor and a skin color or skin tone sensor. These sensors are included, in part, for safety purposes. The skin color / tone sensor is used to adjust the pulse energy based on the color / tone of the area of the subject's skin. For example, as a result, less energy is used for darker skin tones. The skin contact sensor is used to ensure that the flash is activated only when the device is in correct contact with the treatment area. These and other sensors can be incorporated into the treatment device or provided as an attachment to the device.

[0007] In order to obtain an image of the area to be treated and / or the treated area, imaging sensors (e.g., within a camera) are increasingly being included in treatment device 100. In fact, future standards and regulations appear to be evolving in the direction of including imaging sensors in IPL optical engines. The imaging sensor can be used to image the treatment area prior to the deployment of the IPL flash in order to determine whether it is safe to perform the treatment on the area imaged. This includes detecting the skin tone of the area, the condition of the skin, and the presence or absence of any tattoos, moles, and / or other skin features that may affect the suitability and / or safety of the light-based treatment. Other potential uses of the imaging sensor incorporated into the treatment device include treatment guidance via displacement measurement and evaluation of the effectiveness of the treatment.

Summary of the Invention

Problems to be Solved by the Invention

[0008] The high ignition voltage used to initiate plasma breakdown in an IPL treatment device can pose a risk to sensors and / or metal elements incorporated into the device near the gas discharge lamp. The magnitude of the voltage required to ionize the gas in the gas discharge lamp is determined by the type of gas and the gas pressure. The typical ignition voltage of an IPL device is in the range of 12 - 17 kV. At these voltages, nearby sensors / elements are prone to capacitive coupling with the ignition electrode (i.e., an additional external electrode outside the glass tube), and there is a risk of direct voltage discharge from the ignition electrode to the sensors / elements.

[0009] This problem is particularly evident with cameras increasingly incorporated into treatment devices. The imaging sensor of an IPL device is preferably placed near the gas discharge lamp so that an image of the area to be treated / can be treated is obtained. However, placing the imaging sensor near the gas discharge lamp results in capacitive coupling between the imaging sensor and the ignition electrode, which can interfere with the normal function of the imaging sensor. Direct discharge from the high-voltage ignition electrode to the imaging sensor can also damage the imaging sensor, leading to camera failure.

[0010] Therefore, it is desirable to provide a treatment device that reduces the risk of electrical damage within the device due to the high voltage used to initiate plasma breakdown in the gas discharge lamp. Such a treatment device would be more suitable for incorporating additional sensors and elements (such as cameras) than currently available treatment devices.

Means for Solving the Problem

[0011] Accordingly, an object of the present disclosure is to provide an optical-based treatment device in which an imaging sensor and other types of sensors or electrical elements can be incorporated near the gas discharge lamp without impairing the function of the device and / or the sensors / elements.

[0012] According to the disclosure of this book, it is proposed to place an earthed electrode within the treatment device close enough (but not in contact) to the ignition electrode to provide a path to earth. Thus, each time an ignition voltage is applied to enable the generation of an optical pulse, a controlled high-voltage discharge occurs through the earthed electrode. This controlled discharge has been found not to prevent the light source from emitting an optical pulse.

[0013] According to a first aspect, there is provided a treatment device for performing an optical-based treatment operation on or to a target. The treatment device comprises a light source configured to generate optical pulses, the light source comprising a gas, a plasma ignition unit configured to apply a first voltage between the light source and a first electrode to initiate a plasma breakdown of the gas within the light source, an optical output window through which the optical pulses are emitted from the treatment device, and a second electrode connected to earth. The second electrode is spaced apart from the first electrode such that when the first voltage is applied, the first electrode discharges through the second electrode.

[0014] According to a second aspect, there is provided a treatment device for performing an optical-based treatment operation on or to a target. The treatment device comprises a light source configured to generate optical pulses, the light source comprising a housing, a gas within the housing, and two internal electrodes within the housing. The treatment device also comprises a plasma ignition unit configured to apply a first voltage between the light source and a first external electrode outside the housing to initiate a plasma breakdown of the gas within the light source, a capacitor configured to store electrical energy and apply the stored electrical energy to the two internal electrodes to generate an optical pulse when the plasma breakdown of the gas is initiated, and a second external electrode outside the housing and connected to earth. The second external electrode is spaced from the first external electrode such that when the first voltage is applied, the first voltage at the first external electrode discharges through the second external electrode.

[0015] Accordingly, the present invention provides a treatment device in which the risk of electrical damage to sensors and / or other electrical elements within the device is reduced. This is achieved without impairing the function of the treatment device and / or the sensors therein. The present invention can enable sensors such as imaging sensors to be placed close to the light source, such that the imaging sensors can acquire images of the area being treated with light pulses. Alternatively or additionally, the present invention can provide greater freedom in the design of the treatment device, because the sensors and / or electrical elements can be placed closer to the light source than in conventional treatment devices. The grounded electrode provides a controlled (and predictable) discharge during all light pulses, preventing uncontrolled discharges that could damage nearby sensors / elements. The present disclosure also shortens the length of time during which capacitive coupling occurs between the ignition electrode and the sensors within the device.

[0016] These and other aspects will become apparent from and will be elucidated with reference to the embodiments described hereinafter.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Modes for Carrying Out the Invention

[0018] The following exemplary embodiments will be described with reference to the following drawings, which are merely illustrative.

[0019] FIG. 2 is an explanatory diagram of an exemplary treatment device 2 that can be used to apply light pulses to a skin area. It should be understood that the treatment device 2 in FIG. 2 is merely presented as an example of a hand-held treatment device 2 that can be used in the present invention, and the treatment device 2 is not limited to the form shown in FIG. 2, nor is it limited to being a hand-held treatment device. The treatment device 2 is for use on the body of a subject (e.g., a person or an animal) and is held by one or both hands of the user during use. The treatment device 2 performs some treatment operation on the hair on the subject's body using one or more light pulses when the treatment device 2 is in contact with the subject's body part. The treatment operation can be the removal of unwanted hair by laser and / or light treatment (known as laser hair removal treatment or intense pulsed light treatment).

[0020] As described in this document, the treatment device 2 is operated or used by a "user", and the treatment device 2 is used on the body of a "subject". In some cases, the user and the subject are the same person, that is, the treatment device 2 is held by hand and used by the user himself / herself (e.g., used on the skin of the leg). In other cases, the user and the subject are different people. For example, the treatment device 2 is held by hand and used by the user on another person.

[0021] The exemplary treatment device 2 has a housing 4 including at least a handle portion 5 and a head portion 6. The handle portion 5 is shaped to enable the user to hold the treatment device 2 with one hand. The head portion 6 is at the head end 8 of the housing 4 such that a personal care operation is performed on the subject's body or skin at the position where the head portion 6 is in contact with the body or skin, and the head portion 6 is arranged to contact the subject.

[0022] The treatment device 2 is for performing a treatment operation using optical pulses. Thus, in FIG. 2, the head portion 6 has an opening 10, also referred to as a light emission window, which is disposed within or on the housing 4, such that the opening 10 can be disposed adjacent to or on (i.e., in contact with) the skin of the subject. The treatment device 2 includes one or more light sources 12 for generating optical pulses that are applied to the skin of the subject through the opening 10 and result in a treatment operation. The one or more light sources 12 are disposed within the housing 4 such that optical pulses are provided from the one or more light sources 12 through the opening 10. The opening / light emission window 10 can be in the form of an opening at the head end 8 of the housing 4, or it can be in the form of a window (including a waveguide) that is transparent or translucent to the optical pulses (i.e., the optical pulses can pass through the window).

[0023] In the exemplary embodiment shown in FIG. 2, the opening 10 generally has a rectangular shape, which results in a generally rectangular-shaped skin treatment area on the skin. It should be understood that the opening 10 can have any other desired shape. For example, the opening 10 can be square, elliptical, circular, or any other polygonal shape.

[0024] The one or more light sources 12 can generate optical pulses of any suitable or desired wavelength (or range of wavelengths) and / or intensity. For example, the light source 12 can generate visible light, infrared (IR) light, and / or ultraviolet (UV) light. Each light source 12 can have any type of light source to which a high voltage is applied to enable the generation of optical pulses, such as a gas discharge lamp.

[0025] According to the embodiments of this book, at least one of the one or more light sources is a gas discharge lamp (e.g., a xenon flash lamp). The gas discharge lamp can have gas inside a housing (e.g., a glass tube), where the gas is typically a noble gas such as xenon or argon, or a mixture of such gases. In these embodiments, the treatment device 2 also includes a plasma ignition unit for providing a high voltage to initiate plasma breakdown of the gas in the light source. This process will be further described with reference to FIG. 3.

[0026] In some embodiments, the light source 12 generates UV light, visible light, and / or IR light, and filters can be used to absorb some wavelengths. For example, the filter can remove UV light and visible light at the blue end of the spectrum. In some embodiments, light with wavelengths less than 560 nm can be filtered. The resulting light pulse can be emitted from the device with spectral components in the range of 560 to 1800 nanometers (nm). These wavelengths (especially those in the range of 560 to 1200 nm) heat the melanin in the hair and hair follicles by absorption, which puts the hair follicles in the telogen phase and prevents hair growth.

[0027] The one or more light sources 12 are configured to provide pulsed light. That is, the light source 12 is configured to generate light at a high intensity for a short period of time (e.g., less than 1 second). In some examples, the light pulse can have a duration of 4 to 8 milliseconds (ms). The full width at half maximum (FWHM) of the light pulse is about 1.8 ms. The intensity of the light pulse must be high enough to perform a treatment operation on the skin or body part adjacent to the aperture 10. For example, a home device can provide a light pulse with a fluence up to 6.5 J / cm2, while a commercial device can provide a light pulse with a fluence exceeding 10 J / cm2.

[0028] The treatment device 2 described is also used to determine whether the head portion 6 is in contact with the skin before a light pulse is generated, in order to avoid the light pulse being directed towards the eyes of the user or the subject, and includes two skin contact sensors 14, 16 disposed on or within the head portion 6.

[0029] The treatment device 2 described includes an imaging sensor 18 disposed in the head portion 6 and near one or more light sources 12. In some embodiments, the imaging sensor 18 can be configured to acquire an image of the area of skin to be treated, being treated, or that has been treated. For example, the imaging sensor 18 can be used to determine the condition of the skin to be treated and / or to determine whether the treatment area includes any tattoos, moles, and / or other skin features that can affect the suitability and / or safety of a light-based treatment.

[0030] Alternatively or additionally, the imaging sensor 18 may be configured to determine the skin tone of the skin to be treated. The skin tone can be determined in order to ensure that the light pulse has an intensity suitable for the type of skin being treated, or to prevent the light pulse from being generated if the skin type is not suitable for the light pulse (e.g., very dark skin with a much higher melanin content). The imaging sensor 18 can determine the skin tone by measuring the intensity or level of light of a specific wavelength or wavelengths reflected from the skin. The measured intensity or level of the reflected light at a specific wavelength can indicate the skin tone. The measured intensity or level of the reflected light can be based on the melanin concentration in the skin, and thus the measured intensity or level can indicate the melanin concentration. The melanin concentration can be obtained, for example, from measurements of light reflection at wavelengths of 660 nm (red) and 880 nm (infrared).

[0031] In some embodiments, the imaging sensor 18 can be configured to determine whether the head portion 6 of the device is in contact with the subject's skin. In these embodiments, the imaging sensor 18 can be used instead of or in combination with the skin contact sensors 14, 16 described above.

[0032] The imaging sensor 18 can be, for example, the imaging sensor 104 described with reference to any one of FIGS. 4 to 6.

[0033] The treatment device 2 to be described also includes a user control unit 20 that can be operated by a user to operate the treatment device 2. As a result, the head unit 6 performs a treatment operation required on the target body (for example, generation of one or more light pulses by one or more light sources 12). The user control unit 20 can be in the form of a switch, a button, a touch pad, or the like.

[0034] As described above, there are problems associated with incorporating an imaging sensor and / or other sensors into an IPL treatment device as depicted in FIGS. 1 and 2. These problems are described with reference to FIG. 3.

[0035] A part of the treatment device 100 depicted in FIG. 1 is shown in FIG. 3 together with an imaging sensor 104 disposed near the lamp 101 and the reflector 102. The reflector 102 has an opening. As a result, the imaging sensor 104 can obtain an image of the target skin 103 through a light emission window (not shown) and the (for example, glass) housing of the lamp 101. In this example, the lamp 101 is a gas discharge lamp such as a xenon flash lamp. Inside the housing of the lamp 101, there are two internal electrodes 130 that can be connected to one or more capacitors 132. The capacitor 132 is outside the housing (glass tube) of the lamp 101 and stores the electrical energy necessary to apply a voltage across the internal electrodes 130 to generate a flash. In practice, at least a part of each internal electrode 130 is inside the glass tube, and they can extend to the outside of the glass tube and be connected to the capacitor 132.

[0036] As described with reference to FIG. 1, the apparatus 100 has a plasma ignition unit 108, which is configured to apply an ignition voltage between the reflector 102 and an electrode of the lamp 101, for example one of the two internal electrodes 130 (forming an open circuit), at the start of every flash. The ignition voltage must be high enough to form a plasma, i.e., to ionize the gas atoms and / or molecules in the gas discharge lamp 101. For a typical IPL apparatus, the ignition voltage ranges from 5 to 30 kV. Preferably, the ignition voltage ranges from 12 to 17 kV. In some examples, the ignition voltage is 15 kV.

[0037] When the reflector 102 is placed under high voltage (e.g., when the reflector 102 functions as an external electrode for the ignition voltage), capacitive coupling occurs between the reflector 102 and any conductive element in its vicinity. Thus, the configuration shown in FIG. 3 results in a capacitive coupling 105 between the reflector 102 and the imaging sensor 104. The imaging sensor 104 is also at risk of receiving a direct discharge from the reflector 102. Such capacitive coupling and / or voltage discharge (depicted by the dashed arrow 105 in FIG. 3) can interfere with the normal functioning of the imaging sensor and can lead to short-term or long-term damage to the imaging sensor involved.

[0038] To address these and other problems, a treatment device is provided for performing a light-based treatment operation on or to a target. The treatment device includes a light source including a housing, a gas within the housing, two internal electrodes within the housing, a plasma ignition unit configured to apply a first voltage between the light source and a first external electrode external to the housing to initiate a plasma breakdown of the gas within the light source, a capacitor configured to store electrical energy and apply the stored electrical energy to the two internal electrodes to generate a light pulse when the plasma breakdown of the gas is initiated, and a second external electrode external to the housing and connected to electrical ground. The second external electrode is spaced apart from (i.e., not in contact with) the first external electrode such that when the first voltage is applied, the first voltage at the first external electrode discharges through the second external electrode.

[0039] The treatment device may be an intense pulsed light (IPL) device for performing IPL photoepilation. The light source may be a gas discharge lamp such as a flash lamp. Examples of gases used for flash lamps include xenon, argon, and krypton. In some embodiments, the flash lamp may have a molecular gas and / or a mixed gas.

[0040] The light source may have a housing (e.g., a glass tube) that houses the gas. The light source further has at least two internal electrodes (different from the first and second external electrodes described above) that are spaced apart from each other such that there is gas between these electrodes. The two internal electrodes are at least partially disposed within the lamp housing and are connected to one or more capacitors external to the housing. The capacitor stores the electrical energy necessary to apply a voltage between the internal electrodes to generate a flash. A switching device may be present to control the discharge of one or more capacitors across the two internal electrodes.

[0041] The plasma ignition unit is configured to apply a first voltage (also referred to as the ignition voltage in this document) between a light source and a first external electrode (also referred to as the ignition electrode in this document) to initiate plasma breakdown of the gas within the light source. The first voltage can be between one of the internal electrodes 130 of the lamp 101 and the first external electrode. Preferably, the internal electrode 130 used here is a negative electrode. In some embodiments, the first voltage is between 5 and 30 kV. Preferably, the first voltage is between 12 and 17 kV.

[0042] The first external electrode can be any suitable conductive element. For example, in some embodiments, the first electrode is part of a reflector that is also used to direct light pulses to the light-emitting window. In other embodiments, the first external electrode is part of a metal element (such as a metal wire) wound around the light source.

[0043] The first external electrode is included in the treatment device. In some embodiments, the first external electrode is disposed outside the light source for external triggering of the light source. In these embodiments, the first external electrode may be in contact with the light source (e.g., in contact with the housing (such as a glass tube)), or may be spaced from the light source but disposed proximal to the light source (i.e., in the vicinity of the light source). In some embodiments, "proximal" may mean spaced between 0.1 mm and 2 mm from the light source. The first external electrode is outside the complete outer side / exterior of the housing / glass tube of the lamp 101.

[0044] Although not shown in FIG. 3, the treatment device has a light-emitting window through which light pulses are emitted from the treatment device. The light-emitting window may be an opening, such as a hole / aperture in the housing of the treatment device. Alternatively, the light-emitting window may be a translucent or transparent material (such as glass or plastic) through which light passes.

[0045] In some embodiments, the treatment device further includes a sensor. For example, the sensor can be an imaging sensor for obtaining one or more images of an area or region in the vicinity of the treatment device, such as an area of skin being treated with an optical pulse or an area of skin that has been treated with an optical pulse. The imaging sensor obtains one or more images using light passing through the treatment device. Alternative types of sensors include a skin contact sensor or a skin tone sensor. The sensor can be for sensing one or more of skin contact, skin color, hair color, freckles, tattoos, and skin condition. In the case of the imaging sensor, the image obtained by the imaging sensor can be analyzed to determine any one or more of skin contact, skin color, hair color, freckles, tattoos, and skin condition.

[0046] In embodiments where a sensor is present within the treatment device, at least a portion of the second external electrode is closer to the first external electrode than any portion of the sensor. In other words, at least a portion of the second external electrode is spaced apart from the first external electrode by a distance less than the minimum distance between the sensor and the first external electrode. This ensures that the first voltage discharges to ground through the second external electrode rather than through the sensor.

[0047] In some embodiments, the minimum distance between the second external electrode and the first external electrode is equal to or less than the air breakdown distance of the first voltage at atmospheric pressure. This positioning reduces the risk of electrical damage to the sensor. Each time the first (ignition) voltage is applied, a high-voltage discharge occurs to the grounded second external electrode. This reduces the duration of capacitive coupling to the sensor. Further, the high-voltage discharge to the grounded second external electrode prevents a high-voltage discharge to the sensor.

[0048] The inclusion of the second external electrode provides a controlled voltage discharge each time a flash is generated. An ignition voltage (e.g., about 15 kV) is required to initiate plasma breakdown in the flash lamp. Therefore, this controlled discharge of the voltage is expected to impair the normal function of the flash lamp. In other words, when the ignition voltage discharges, there is no ignition voltage to (partially) ionize the gas in the light source (i.e., to initiate plasma breakdown), and thus it is expected that no flash will be generated. However, experimental observations show that when the grounded second external electrode is not in conductive contact with the ignition first external electrode (i.e., when there is no conductive path between the ignition first external electrode and the grounded second external electrode), the controlled discharge does not prevent the emission of a strong light pulse. This experimental observation shows that when the ignition first external electrode is separated from the grounded second external electrode, the time required to initiate plasma breakdown is shorter than the time required for the controlled discharge of the ignition voltage. Therefore, the controlled discharge does not prevent plasma breakdown. Conversely, when the ignition first external electrode is in conductive contact with the grounded second external electrode, the ignition voltage discharges directly to ground and no plasma breakdown occurs, thus preventing the generation of an IPL flash.

[0049] As disclosed herein, the inclusion of a grounded second external electrode spaced from the first external electrode provides a path for current to flow to ground in a controlled manner. This controlled discharge prevents any imaging sensor or any other element within the device from becoming part of the high voltage discharge path, and thus protects such elements from electrical damage. The grounded second external electrode also reduces the duration of any capacitive coupling between (i) the ignition first external electrode within the lamp and (ii) the imaging sensor or other sensor / element. Thus, a sensor (such as an imaging sensor) and / or other elements can be included in the treatment device in a manner that reduces the risk of electrical damage to the sensor / element without impairing the function of the treatment device.

[0050] Specific embodiments of the present invention are schematically illustrated in FIGS. 4, 5, 6, 7 and 8.

[0051] Figure 4 shows a treatment device 100 including an imaging sensor 104 disposed near a lamp 101 and a reflector 102. Two internal electrodes 130 are present inside the housing of the lamp 101 (e.g., inside a glass tube) and are connected to one or more capacitors 132. The capacitor 132 stores the electrical energy necessary to apply a voltage across the internal electrodes 130 to generate treatment light pulses.

[0052] The imaging sensor is configured to obtain one or more images using light passing through the treatment device. The obtained images can be, for example, images of the skin 103 before and / or after treatment. It should be understood that the present invention is equally applicable to other sensors or elements instead of, or in addition to, the imaging sensor 104.

[0053] The reflector 102 in Figure 4 has a dual function. First, it reflects treatment light pulses towards the target skin 103. Second, it functions as a high-voltage first external electrode for the ignition voltage used to initiate plasma breakdown in the lamp 101. The treatment device 100 also has a second external electrode 106 connected to an electrical ground 107. The second external electrode 106 is spaced apart from the reflector 102 (the first external electrode). As a result, each time the plasma ignition unit 108 applies a first voltage (i.e., the ignition voltage) between the reflector 102 and the lamp 101, a high voltage in the reflector 102 discharges through the second external electrode 106. It has been experimentally observed that this high-voltage discharge to the grounded second external electrode 106 does not interfere with the normal function of the lamp 101 and thus does not interfere with IPL emission.

[0054] The minimum distance between the second external electrode 106 and the reflector 102 (the first external electrode) is equal to or less than the air insulation breakdown distance of the first voltage at atmospheric pressure. This ensures that a high-voltage discharge to the second external electrode 106 occurs each time the ignition voltage is applied.

[0055] FIG. 5 shows an alternative embodiment, where the second external electrode 106 is the case or housing in which the imaging sensor 104 is disposed, such as a metal case around a camera. In other embodiments, the second external electrode 106 can be the case in which any other type of sensor is disposed. The case 106 is connected to the electrical ground 107, electrically insulated from the imaging sensor 104 contained therein, and spaced apart from the reflector 102 (the first external electrode). As a result, each time a first voltage (i.e., ignition voltage) is applied between the reflector 102 and the lamp 101, the reflector 102 discharges through the second external electrode 106. The current flows to the ground in a controlled manner and thus does not pass through the imaging sensor 104 (or other sensor).

[0056] A disadvantage of integrating the imaging sensor 104 into the path of the treatment light in the treatment device 100 is the possibility of electromagnetic interference (EMI) due to the ignition of the lamp 101. For example, a high voltage (e.g., 15 kV) may be used for the reflector 102 (the first external electrode) behind the flash lamp 101 to initiate the plasma channel inside the lamp 101. EMI is a disturbance generated by an external source that affects an electrical circuit by electromagnetic induction, electrostatic coupling, or conduction. This disturbance may degrade the performance of the imaging unit 104 or even stop its function.

[0057] The second external electrode 106 can be the metal case or housing in which the imaging sensor 104 is disposed. In principle, in this solution, the imaging sensor 104 can be sufficiently shielded from EMI. However, the case or housing requires an opening to enable the imaging sensor 104 to acquire an image, and substantial EMI may occur through the unshielded optical path leading to the imaging unit 104 through the opening.

[0058] An exemplary embodiment of the case arrangement 110 of the imaging sensor 104 for improving the EMI shield is shown in FIG. 6. The case arrangement 110 has an imaging sensor 104 housed in a conductive housing 112 that functions as a second external electrode 106. In this illustrated embodiment, the imaging sensor 104 has an LED light illumination ring 114 used to generate light for illuminating the skin 103 to be imaged. The illumination ring 114 can be composed of a finite number, for example, three or four LEDs. In other embodiments of the case arrangement 112, the illumination ring 114 can be omitted or arranged in another part of the treatment device 100.

[0059] The conductive housing 112 is in the form of an open-ended housing, for example, a box with one end open, through which the imaging unit 104 obtains an image. A metal-coated triangular prism 116 made of, for example, glass or optical plastic reflects the light from the illumination ring 114 (referred to as the "illumination beam") downward to the exit side of the prism 116. The metal coating is applied to the hypotenuse surface 118 of the prism 116, where it functions as an EMI shield and as a mirror for the illumination beam and the light reflected from the skin 103. The metal coating is also applied to the triangular side surface 120, which functions as an EMI shield. The exit surface of the prism 116 is covered with a conductive (e.g., metal) nanowire grid 122 that functions as a light polarizer. The direction of the nanowire grid 122 is preferably aligned parallel to the major axis of the opening / light exit window 10 of the treatment device 100 to ensure the best angular performance in that direction. Optionally, the light from the illumination ring 114 is pre-polarized by an absorption or reflection polarizer film to prevent excessive internal reflection returning from the wire grid polarizer 122 to the imaging sensor 104. In front of the nanowire grid polarizer 122, there can be a plate of an achromatic λ / 4 (i.e., 1 / 4 wavelength) retarder 124 that converts linearly polarized light to circularly polarized light during emission. On the other hand, the specularly reflected light has its 180° phase reversed and becomes cross-polarized when returning, preventing the specularly reflected light from entering the imaging sensor 104. The light passing through the polarizer filter is reflected by the hypotenuse surface 118 of the prism 116 towards the imaging sensor 104.

[0060] Optionally, the conductive housing 112 is configured to have a high external reflectivity. This promotes the reflection of the treatment light pulse when the treatment light pulse hits the housing 112 around the imaging sensor 104, thereby resulting in a minimum loss of light power at the aperture / light exit window 10.

[0061] The conductive housing 112 may be a hollow cylinder of glass (or plastic) with a lining of metal (e.g., silver / aluminum / copper). In these embodiments, the glass (plastic) wall can serve as a mechanical support and also as an electrical insulator between the Faraday cage formed by the conductive housing 112 and the reflector 102 behind the flash lamp 101 to which a firing voltage of 15 kV is applied.

[0062] FIG. 7 is a schematic view of the case arrangement 110 of FIG. 6 in a portion of the treatment device 100 according to various embodiments. The case arrangement 110 and the imaging sensor 104 are shown within an optical cavity within the treatment device 100, formed by the shape of the reflector 102 and bounded by the aperture / light exit window 10. The lamp 101 is also shown in FIG. 7. Thus, the case arrangement 110 is configured such that the plane of the nanowire grid polarizer 122 is parallel to the plane of the aperture / light exit window 10.

[0063] FIG. 8 shows an alternative embodiment of the first external electrode 102, where the first external electrode is a metal wire 102 wound around the lamp 101. Thus, the metal wire 102 (or a similar type of metal element such as a strip) can function as the first external electrode for the firing voltage. Each time the plasma ignition unit 108 applies a firing voltage between the lamp 101 and the metal wire 102, a controlled discharge occurs with respect to the grounded second external electrode 106, thereby protecting the imaging sensor 104.

[0064] Accordingly, there is provided a treatment device for performing a light-based treatment operation on or with respect to a subject, wherein the treatment device is configured such that the risk of electrical damage to sensors and / or elements in the vicinity of a light source included therein is reduced as compared to conventional treatment devices.

[0065] Variations to the disclosed embodiments can be understood and effected by those skilled in the art in light of the drawings, disclosure, and appended claims, in practicing the principles and techniques described herein. 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 advantageously used. 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 communication systems. Any reference signs in the claims should not be construed as limiting the scope of the invention.

Claims

Claim 1 A treatment device for performing a light-based treatment operation on or against a target, wherein the treatment device comprises: A light source for generating light pulses, the light source including a housing, a gas in the housing, and two internal electrodes in the housing; A plasma ignition unit for applying a first voltage between the light source and a first external electrode outside the housing to initiate plasma breakdown of the gas in the light source; A capacitor for storing electrical energy and applying the stored electrical energy to the two internal electrodes to generate the light pulses when plasma breakdown of the gas is initiated; A second external electrode outside the housing and connected to electrical ground; The treatment device, wherein the second external electrode is spaced from the first external electrode, and when the first voltage is applied, the first voltage at the first external electrode discharges through the second external electrode. Claim 2 The treatment device according to claim 1, further comprising a sensor. Claim 3 The treatment device according to claim 2, wherein the sensor is an imaging sensor for obtaining one or more images using light passing through the treatment device. Claim 4 The treatment device according to claim 2 or 3, wherein the sensor is for sensing one or more of skin contact, skin color, hair color, moles, tattoos, and skin condition. Claim 5 The treatment device according to claim 2 or 3, wherein the second external electrode is a case in which the sensor is disposed. Claim 6 The treatment device according to claim 5, wherein the case has a conductive housing for the sensor that provides shielding from electromagnetic interference EMI due to the first voltage at the first external electrode. Claim 7 The treatment device according to claim 5, wherein the sensor is an imaging sensor for obtaining one or more images using light passing through the treatment device, and the conductive housing has an open end through which the light passes. The case further includes a triangular prism having two triangular side surfaces, a first surface, a second surface, and a hypotenuse surface, the first surface being disposed adjacent to the open end of the conductive housing, light entering the triangular prism at the second surface being reflected from the hypotenuse surface toward the first surface, the second surface being covered with a conductive nanowire grid that acts as a light polarizer for incident light, and the hypotenuse surface and the triangular side surfaces being metal-coated to provide shielding of the imaging sensor from EMI by the first voltage at the first external electrode, the treatment device according to claim 6.

8. The treatment device according to claim 2 or 3, wherein at least a part of the second external electrode is closer to the first external electrode than any part of the sensor.

9. The treatment device according to claim 2 or 3, wherein the sensor is disposed within the treatment device such that the light pulse senses one or more parameters of the object through a light exit window from which the light pulse is emitted from the treatment device.

10. The treatment device according to any one of claims 1 to 3, wherein the first external electrode is a metal element.

11. The treatment device according to any one of claims 1 to 3, wherein the first external electrode is a reflector that guides the light pulse to the light exit window.

12. The treatment device according to any one of claims 1 to 3, wherein a minimum distance between the second external electrode and the first external electrode is equal to or less than an air breakdown distance of the first voltage at atmospheric pressure.

13. The treatment device according to any one of claims 1 to 3, wherein the first voltage is between 12 and 17 kV.

14. The treatment device according to any one of claims 1 to 3, wherein the light source is a gas discharge lamp.

15. The treatment device according to claim 14, wherein the gas discharge lamp is a flash lamp.

16. The treatment device according to any one of claims 1 to 3, wherein the treatment operation is intense pulsed light IPL photoepilation.

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