Phototherapy 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 light-based treatment operations on or to an object. [Background technology]

[0002] Hair removal techniques include shaving, electrolysis, plucking, laser and light therapy (known as photoepilation), and therapeutic antiandrogen injections. Light-based techniques are also used in other types of dermatological treatments, including hair growth reduction and acne treatment.

[0003] Light-based hair treatments inhibit hair growth by exposing the skin to bright flashes or pulses of light known as Intense Pulsed Light (IPL). Through the use of the appropriate configuration of light energy, i.e. wavelength, intensity and / or pulse time (if the light is pulsed), selective heating of the hair root and subsequent temporary or permanent damage to the hair follicle can be achieved. IPL can be produced 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 root, particularly by the melanin pigment. This results in an increase in the temperature of the hair root and subsequently in the temperature of the surrounding tissue. The heat generated damages the hair follicle and, if the temperature increase is sufficient, inhibits hair growth. This process is known as photothermolysis.

[0004] Light-based hair removal can be performed using commercially available "home" devices (consumer devices suitable for non-professional use), such as the Philips Lumea device. Home devices typically use IPL technology at relatively low fluences (e.g., up to 6.5 J / cm2) compared to commercial devices, which use fluences of over 10 J / cm2. Long-lasting hair reduction is achieved when treatments are repeated at 2- to 4-week intervals.

[0005] FIG. 1 is a schematic diagram showing some of the elements of an IPL treatment device 100. The device 100 comprises a gas discharge lamp 101 that generates an intense light pulse (also referred to herein as a flash) and an optical reflector 102 positioned to direct the light pulse towards the skin 103 of a subject. The gas discharge lamp 101 comprises a gas within a housing, e.g. 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 an electrical discharge. The voltage can be applied, for example, via an internal electrode 130 inside both ends of the glass tube. The internal electrode 130 is connected to one or more capacitors 132 (external to the glass tube) that store the electrical energy required for the voltage applied across the internal electrode 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, an 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) that is outside the glass tube. The additional external electrode (also referred to herein as the ignition electrode or "first external electrode") can be any conductive element, for example a metal element. In the example shown in FIG. 1, the reflector 102, which is a metal element, is used as the additional external electrode. As a result, an 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 that is wound around the glass tube. The metal element can be in the form of a wire or strip. In FIG. 1, the ignition voltage between the lamp 101 and the reflector 102 is generated by a plasma ignition unit 108.

[0006] The treatment device 100 can include various sensors that are 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 subject's skin area, e.g., so that less energy is used for darker skin tones. The skin contact sensor is used to ensure that the flash is only enabled when the device is properly in contact with the treatment area. These and other sensors can be built into the treatment device or provided as attachments to the device.

[0007] Imaging sensors (e.g., in cameras) are also increasingly being included in treatment devices 100 to obtain images of the area to be treated and / or the area that has been treated. In fact, future standards and regulations appear to be evolving toward including imaging sensors in the IPL optical engine. The imaging sensor can be used to image the treatment area before the IPL flash is deployed to determine if it is safe to perform the treatment on the imaged area. 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 applications of imaging sensors incorporated into treatment devices include treatment guidance via displacement measurements and evaluation of the effectiveness of the treatment. Summary of the Invention [Problem to be solved by the invention]

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

[0009] This problem is especially seen in cameras that are increasingly integrated into treatment devices. The imaging sensor of an IPL device is preferably placed close to a gas discharge lamp so that an image of the area that is / will be treated is obtained. However, placing the imaging sensor close to the gas discharge lamp results in capacitive coupling between the imaging sensor and the ignition electrode, which may prevent the imaging sensor from functioning properly. Direct discharge from the high voltage ignition electrode to the imaging sensor may also damage the imaging sensor and cause the camera to fail.

[0010] It would therefore be desirable to provide a treatment apparatus that reduces the risk of electrical damage within the apparatus due to the high voltages used to initiate plasma breakdown in a gas discharge lamp. Such a processing device would be better suited to incorporating additional sensors and elements (such as cameras) than currently available processing devices. [Means for solving the problem]

[0011] It is therefore an object of the present disclosure to provide a light-based treatment device in which imaging sensors and other types of sensors or electrical elements can be incorporated near a gas discharge lamp without compromising the functionality of the device and / or the sensors / elements.

[0012] In accordance with the disclosure herein, it is proposed to place a grounded electrode in the treatment device close enough to (but not touching) the ignition electrode to provide a path to electrical ground. Thus, a controlled high voltage discharge occurs through the grounded electrode each time an ignition voltage is applied to enable a light pulse to be generated. It has been found that this controlled discharge does not prevent the light source from emitting the light pulse.

[0013] According to a first aspect, a treatment device for performing a light-based treatment operation on or at a subject is provided. The treatment device includes a light source configured to generate light pulses, the light source including a gas, a plasma ignition unit configured to apply a first voltage between the light source and a first electrode to initiate plasma breakdown of the gas in the light source, a light exit window through which the light pulses are emitted from the treatment device, and a second electrode connected to an electrical ground. The second electrode is spaced apart from the first electrode such that the first electrode discharges through the second electrode when the first voltage is applied.

[0014] According to a second aspect, a treatment device for performing a light-based treatment operation on or at a subject is provided. The treatment device includes a light source configured to generate light pulses, the light source including a housing, a gas in the housing, and two internal electrodes in the housing. The treatment device also includes a plasma ignition unit configured to apply 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 configured to store electrical energy and apply the stored electrical energy to the two internal electrodes to generate light pulses when plasma breakdown of the gas is initiated, and a second external electrode outside the housing and connected to electrical ground. The second external electrode is spaced apart from the first external electrode such that the first voltage at the first external electrode discharges through the second external electrode when the first voltage is applied.

[0015] Thus, the present invention provides a treatment device with reduced risk of electrical damage to sensors and / or other electrical elements within the device. This is accomplished without compromising the functionality of the treatment device and / or sensors therein. The present invention can allow a sensor, such as an imaging sensor, to be placed closer to the light source so that the imaging sensor can capture an image of the area being treated with the light pulse. Alternatively or additionally, the present invention can provide greater freedom in the design of the treatment device because the sensor 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 every light pulse, preventing uncontrolled discharges that could damage nearby sensors / elements. The present disclosure also reduces the amount of time that capacitive coupling occurs between the ignition electrode and the sensor within the device.

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

[0017] [Figure 1] FIG. 2 is a schematic diagram showing some of the elements of the treatment device. [Diagram 2] FIG. 1 is an illustration of an exemplary treatment device. [Diagram 3] FIG. 1 is a schematic diagram illustrating a problem that may occur with a treatment device. [Figure 4] 1 is a schematic diagram of portions of a treatment device according to various embodiments. [Diagram 5] 1 is a schematic diagram of portions of a treatment device according to various embodiments. [Figure 6] 1 is a schematic diagram of an imaging sensor case arrangement according to various embodiments. [Figure 7] 7 is a schematic diagram of the case arrangement of FIG. 6 in a portion of a treatment device according to various embodiments. [Figure 8] 1 is a schematic diagram of portions of a treatment device according to various embodiments. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Exemplary embodiments will now be described, by way of example only, with reference to the following drawings, in which:

[0019] FIG. 2 is an illustration of an exemplary treatment device 2 that can be used to apply light pulses to an area of ​​skin. It should be understood that the treatment device 2 of FIG. 2 is presented only as one example of a handheld treatment device 2 with which the present invention can be used, and that the treatment device 2 is not limited to the form shown in FIG. 2 or to being a handheld treatment device. The treatment device 2 is for use on the body of a subject (e.g., a human or animal) and is held in one or both hands of a user during use. The treatment device 2 performs some treatment operation on hair on the subject's body using one or more light pulses when the treatment device 2 is in contact with a body part of the subject. The treatment operation can be the removal of unwanted hair by laser and / or light treatment (known as photoepilation treatment or intense pulsed light treatment).

[0020] As described herein, the treatment device 2 is operated or used by a "user" and the treatment device 2 is applied to the body of a "subject." In some cases, the user and the subject are the same person, i.e., the treatment device 2 is held in the hand and used by the user himself (e.g., applied to the skin of the leg). In other cases, the user and the subject are different people, e.g., the treatment device 2 is held in the 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 allow a user to hold the treatment device 2 in one hand. The head portion 6 resides at a head end 8 of the housing 4, and the head portion 6 is positioned to contact a subject, such that a personal care operation is performed on the subject's body or skin with the head portion 6 in contact with the body or skin.

[0022] The treatment device 2 is for performing a treatment operation using light pulses. Thus, in FIG. 2, the head portion 6 has an opening 10, also called a light exit window, which is arranged in or on the housing 4, so that the opening 10 can be arranged 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 light 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 arranged in the housing 4 such that the light pulses are provided from the one or more light sources 12 through the opening 10. The opening / light exit window 10 can be in the form of an opening in 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 semi-transparent to the light pulses (i.e. the light pulses can pass through the window).

[0023] In the exemplary embodiment shown in Figure 2, the opening 10 has a generally 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, oval, circular, or any other polygonal shape.

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

[0025] According to embodiments herein, at least one of the one or more light sources is a gas discharge lamp (e.g., a xenon flash lamp). A gas discharge lamp may have a gas in 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 is further described with reference to FIG. 3.

[0026] In some embodiments, the light source 12 generates UV, visible and / or IR light, and filters may be used to absorb some wavelengths. For example, the filters may remove UV light and visible light at the blue end of the spectrum. In some embodiments, light with wavelengths less than 560 nm may be filtered. The resulting light pulses may be emitted from the device with spectral content in the range of 560-1800 nanometers (nm). These wavelengths (especially those in the range of 560-1200 nm) heat up the melanin in the hair and hair roots upon absorption, which puts the hair follicle into 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 4-8 milliseconds (ms). The full width at half maximum (FWHM) of the light pulse is about 1.8 ms. The intensity of the light pulse should be high enough to perform a treatment operation on the skin or body part adjacent to the opening 10. For example, a home device can provide light pulses with a fluence of up to 6.5 J / cm2, while a commercial device can provide light pulses with a fluence of more than 10 J / cm2.

[0028] The described treatment device 2 also includes two skin contact sensors 14, 16 located on or within the head portion 6 that are used to determine whether the head portion 6 is in contact with the skin before the light pulse is generated to avoid directing the light pulse into the user's or subject's eyes.

[0029] The illustrated treatment device 2 includes an imaging sensor 18 disposed in the head portion 6 and positioned near the one or more light sources 12. In some embodiments, the imaging sensor 18 may be configured to acquire images of an area of ​​skin to be treated, being treated, or having been treated. For example, the imaging sensor 18 may be used to determine the condition of the skin being treated and / or whether the treatment area includes any tattoos, moles, and / or other skin features that may 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 being treated. The skin tone can be determined to ensure that the light pulses have an appropriate intensity for the type of skin being treated or to prevent light pulses from being generated if the skin type is not suitable for the light pulses (e.g., 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 at a particular wavelength or wavelengths reflected from the skin. The measured intensity or level of reflected light at a particular wavelength can be indicative of the skin tone. The measured intensity or level of reflected light can be based on the melanin concentration in the skin, and thus the measured intensity or level can be indicative of 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 may be configured to determine whether the head 6 of the device is in contact with the skin of a subject. In these embodiments, the imaging sensor 18 may be used in place of or in conjunction with the skin contact sensors 14, 16 described above.

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

[0033] The illustrated treatment device 2 also includes user controls 20 that can be operated by a user to activate the treatment device 2 such that the head 6 performs the required treatment operation on the subject's body (e.g., generation of one or more light pulses by one or more light sources 12). The user controls 20 can be in the form of a switch, a button, a touch pad, or the like.

[0034] As noted above, there are challenges associated with incorporating imaging and / or other sensors into an IPL treatment device such as those depicted in Figures 1 and 2. These challenges are explained with reference to Figure 3.

[0035] A part of the treatment device 100 depicted in FIG. 1 is shown in FIG. 3 with an imaging sensor 104 located 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 subject's skin 103 through a light exit window (not shown) and the (e.g. 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 capacitors 132 are outside the housing (glass tube) of the lamp 101 and store the electrical energy required 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 to be connected to the capacitors 132.

[0036] As explained with reference to FIG. 1, the device 100 comprises 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 beginning 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 device, the ignition voltage is in the range of 5-30 kV. Preferably, the ignition voltage is in the range of 12-17 kV. In some examples, the ignition voltage is 15 kV.

[0037] When the reflector 102 is subjected to a high voltage (e.g., when the reflector 102 serves as an external electrode for an ignition voltage), capacitive coupling occurs between the reflector 102 and any conductive elements in its vicinity. The configuration shown in Figure 3 thus results in a capacitive coupling 105 between the reflector 102 and the imaging sensor 104. The imaging sensor 104 is also at risk of being directly discharged from the reflector 102. Such capacitive coupling and / or voltage discharge (depicted in Figure 3 by the dashed arrow 105) can disrupt the proper functioning of the imaging sensor and can result in 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 light-based treatment operations in or on a subject. The treatment device includes a light source including a housing, a gas in the housing, two internal electrodes in the housing, a plasma ignition unit configured to apply 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 configured to store electrical energy and apply the stored electrical energy to the two internal electrodes to generate a light pulse when plasma breakdown of the gas is initiated, and a second external electrode outside the housing and connected to electrical ground. The second external electrode is spaced apart (i.e., not in contact) 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.

[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 in the flash lamp include xenon, argon, and krypton. In some embodiments, the flash lamp may have molecular gases and / or mixed gases.

[0040] The light source may have a housing (e.g. a glass tube) in which the gas is contained. The light source further has at least two internal electrodes (different from the first and second external electrodes already mentioned) spaced apart from one another so that the gas is present between them. The two internal electrodes are at least partially disposed within the lamp housing and connected to one or more capacitors that are external to the housing. The capacitors store the electrical energy required to apply a voltage across the internal electrodes to generate the flash. A switching device may be present to control the discharge of the one or more capacitors across the two internal electrodes.

[0041] The plasma ignition unit is configured to apply a first voltage (also referred to herein as ignition voltage) between the light source and a first external electrode (also referred to herein as ignition electrode) to initiate plasma breakdown of the gas in the light source. The first voltage may 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 the light pulse to the light exit window. In other embodiments, the first external electrode is part of a metal element (e.g., a metal wire) that is wrapped around the light source.

[0043] The first external electrode is included in the treatment device. In some embodiments, the first external electrode is located 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 (e.g., glass tube)) or may be spaced from the light source but proximal to the light source (i.e., in the vicinity of the light source). In some embodiments, "proximal" may mean spaced 0.1 mm to 2 mm from the light source. The first external electrode is completely outside / outside the housing / glass tube of the lamp 101.

[0044] Although not shown in FIG. 3, the treatment device has a light exit window through which the light pulses are emitted from the treatment device. The light exit window may be an opening, such as a hole / opening in the housing of the treatment device. Alternatively, the light exit 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 comprises a sensor. For example, the sensor may be an imaging sensor for obtaining one or more images of an area or region proximate the treatment device, such as an area of ​​skin to be treated with light pulses or an area of ​​skin that has been treated with light pulses. The imaging sensor obtains one or more images using light passing through the treatment device. Alternative types of sensors include skin contact sensors or skin tone sensors. The sensor may be for sensing one or more of skin contact, skin color, hair color, moles, tattoos, and skin conditions. In the case of an imaging sensor, the images obtained by the imaging sensor may be analyzed to determine any one or more of skin contact, skin color, hair color, moles, tattoos, and skin conditions.

[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 from the first external electrode by a distance that is less than the minimum distance between the sensor and the first external electrode. This ensures that the first voltage discharges to earth through the second external electrode and not to the sensor.

[0047] In some embodiments, the minimum distance between the second outer electrode and the first outer 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. A high voltage discharge occurs to the grounded second outer electrode every time the first (ignition) voltage is applied. This reduces the length of time of capacitive coupling to the sensor. Additionally, the high voltage discharge to the grounded second outer electrode prevents high voltage discharge to the sensor.

[0048] The inclusion of the second outer 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, a controlled discharge of this voltage is expected to impair the normal functioning of the flash lamp. In other words, if the ignition voltage discharges, there is no ignition voltage to (partially) ionize the gas in the light source (i.e., initiate plasma breakdown), and therefore, no flash is expected to be generated. However, experimental observations show that if the grounded second outer electrode is not in conductive contact with the ignition first outer electrode (i.e., there is no conductive path between the ignition first outer electrode and the grounded second outer electrode), the controlled discharge does not prevent the emission of an intense light pulse. This experimental observation shows that when the ignition first outer electrode is spaced apart from the grounded second outer electrode, the time required to initiate plasma breakdown is shorter than the time required for a controlled discharge of the ignition voltage. Therefore, the controlled discharge does not prevent plasma breakdown. Conversely, if the ignition first outer electrode is in conductive contact with the grounded second outer electrode, the ignition voltage will discharge directly to ground and no plasma breakdown will occur, thus preventing the creation of an IPL flash.

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

[0050] Specific embodiments of the present invention are shown diagrammatically in FIGS.

[0051] 4 shows a treatment device 100 comprising an imaging sensor 104 located near the lamp 101 and the reflector 102. Two internal electrodes 130 reside inside the housing of the lamp 101 (e.g., in a glass tube) and are connected to one or more capacitors 132. The capacitors 132 store the electrical energy required 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 may 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 FIG. 4 has a dual function. First, it reflects the treatment light pulses towards the subject's skin 103. Second, it serves 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 (first external electrode). As a result, the high voltage in the reflector 102 discharges through the second external electrode 106 whenever the plasma ignition unit 108 applies a first voltage (i.e., ignition voltage) between the reflector 102 and the lamp 101. It is experimentally observed that this high-voltage discharge to the grounded second external electrode 106 does not interfere with the normal functioning of the lamp 101 and thus does not interfere with the IPL emission.

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

[0055] FIG. 5 shows an alternative embodiment, in which the second external electrode 106 is a case or housing in which the imaging sensor 104 is placed, for example a metal case around a camera. In other embodiments, the second external electrode 106 can be a case in which any other type of sensor is placed. The case 106 is connected to an electrical ground 107, electrically insulated from the imaging sensor 104 contained therein, and spaced apart from the reflector 102 (first external electrode). As a result, whenever 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 in a controlled manner to ground and thus does not pass through the imaging sensor 104 (or other sensor).

[0056] A drawback of integrating the imaging sensor 104 in 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 on the reflector 102 (first external electrode) behind the flash lamp 101 to initiate a plasma channel inside the lamp 101. EMI is a disturbance generated by an external source that affects an electric circuit by electromagnetic induction, capacitive coupling, or conduction. This disturbance may degrade the performance of the imaging unit 104 or even cause it to stop functioning.

[0057] The second external electrode 106 can be a metal case or housing in which the imaging sensor 104 is placed; in principle, in this solution the imaging sensor 104 can be sufficiently shielded from EMI; however, the case or housing requires an opening to allow the imaging sensor 104 to capture an image, and substantial EMI can occur through an unshielded optical path through the opening to the imaging unit 104.

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

[0059] The conductive housing 112 is in the form of an open-ended housing, e.g., a box open at one end, through which the imaging unit 104 obtains an image. A metal-coated triangular prism 116, e.g., made of glass or optical plastic, reflects the light from the illumination ring 114 (which we will call the "illumination beam") downward to the exit side of the prism 116. A metal coating is applied to the hypotenuse surface 118 of the prism 116, where it acts as an EMI shield and a mirror for the illumination beam and the light reflected from the skin 103. A metal coating is also applied to the triangular side 120, which acts as an EMI shield. The exit face of the prism 116 is covered with a conductive (e.g., metal) nanowire grid 122, which acts as a light polarizer. The orientation of the nanowire grid 122 is preferably aligned parallel to the long axis of the aperture / 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 absorbing or reflective polarizer film to prevent excessive internal reflection from the wire grid polarizer 122 back to the imaging sensor 104. In front of the nanowire grid polarizer 122 there can be a plate of achromatic λ / 4 (i.e., quarter-wave) retarder 124 that converts linearly polarized light to circularly polarized light on emission, while the specularly reflected light is 180° out of phase and cross-polarized on return, preventing the specularly reflected light from reaching the imaging sensor 104. Light that passes through the polarizer filter is reflected by the hypotenuse 118 of the prism 116 towards the imaging sensor 104.

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

[0061] The conductive housing 112 may be a hollow cylinder of glass (or plastic) with a metal (e.g., silver / aluminum / copper) lining. In these embodiments, the glass (plastic) wall can provide mechanical support and double 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 the ignition voltage of 15 kV is applied.

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

[0063] 8 shows an alternative embodiment of the first external electrode 102, in which 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 serve as the first external electrode for the ignition voltage. Whenever the plasma ignition unit 108 applies an ignition voltage between the lamp 101 and the metal wire 102, a controlled discharge occurs to the earthed second external electrode 106, thereby protecting the imaging sensor 104.

[0064] Thus, a treatment device is provided for performing a light-based treatment operation on or against an object, where the treatment device is configured such that a risk of electrical damage to sensors and / or elements proximate a light source contained therein is reduced compared to conventional treatment devices.

[0065] Variations to the disclosed embodiments can be understood and implemented by those skilled in the art implementing the principles and techniques described herein, from a study of the figures, the disclosure, and the appended claims. In the claims, the word "comprises" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. A processor or other unit may fulfill the functions of several items recited in the claims. The mere fact that certain means are recited in mutually different dependent claims does not indicate that a combination of these means cannot be used to advantage. The computer program can 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 can 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 interpreted as limiting the scope of the invention.

Claims

1. 1. A treatment device for performing a light-based treatment operation on or to an object, the treatment device comprising: a light source for generating light pulses, the light source including a housing, a gas in the housing, and two internal electrodes within the housing; a plasma ignition unit for applying a first voltage between the light source and a first external electrode external to the housing to initiate plasma breakdown of gas in the light source; a capacitor for storing electrical energy and applying the stored electrical energy to the two inner electrodes to generate the light pulse when plasma breakdown of the gas is initiated; a second external electrode external to the housing and connected to electrical ground; the second external electrode is spaced apart 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.

2. The treatment device of claim 1 , further comprising a sensor.

3. The treatment device of claim 2 , wherein the sensor is an imaging sensor that obtains one or more images using light passing through the treatment device.

4. 4. The treatment device of claim 2 or 3, wherein the sensor is for sensing one or more of skin contact, skin color, hair color, moles, tattoos, and skin conditions.

5. The treatment device according to claim 2 , wherein the second external electrode is a case in which the sensor is disposed.

6. 6. The treatment device of claim 5, wherein the case includes a conductive housing for the sensor that provides shielding from electromagnetic interference (EMI) due to the first voltage at the first external electrode.

7. the sensor is an imaging sensor that obtains one or more images using light passing through the treatment device, the conductive housing having an open end through which the light passes; 7. The treatment device of claim 6, wherein the case further comprises a triangular prism having two triangular shaped sides, a first surface, a second surface, and a hypotenuse surface, the first surface being disposed adjacent the open end of the conductive housing, light entering the triangular prism at the second surface being reflected from the hypotenuse surface towards the first surface, the second surface being covered with a conductive nanowire grid that acts as an optical polarizer for incident light, and the hypotenuse surface and the triangular shaped sides being metal-coated to provide shielding of the imaging sensor from EMI due to the first voltage at the first external electrode.

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

9. 9. The treatment device of claim 2, wherein the sensor is disposed within the treatment device to sense one or more parameters of the subject through a light exit window through which the light pulses are emitted from the treatment device.

10. The treatment device of claim 1 , wherein the first external electrode is a metallic element.

11. The treatment device according to claim 1 , wherein the first external electrode is a reflector that guides the light pulse to the light exit window.

12. 12. The treatment device of claim 1, 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. 13. The treatment device of claim 1, wherein the first voltage is between 12 and 17 kV.

14. 14. The treatment device of claim 1, wherein the light source is a gas discharge lamp.

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

16. The treatment device according to any one of claims 1 to 15, wherein the treatment operation is intense pulsed light (IPL) photoepilation.

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