A pulsed light hair removal device and method based on spectral conversion

Abstract

This invention provides a pulsed light hair removal device and method based on spectral conversion. The pulsed light hair removal device based on spectral conversion includes: a solid-state light-emitting device, a spectral conversion layer, and a skin contact window; the solid-state light-emitting device emits narrow-spectrum pump light; the spectral conversion layer is disposed on one side of the solid-state light-emitting device and is used to absorb the light field and convert it into incoherent broadband pulsed light; the skin contact window is disposed on the light-emitting side of the spectral conversion layer and is used to guide the incoherent broadband pulsed light to the skin surface. This invention provides a pulsed light hair removal device based on spectral conversion. By adopting an architecture combining a solid-state light-emitting device and a spectral conversion layer, the high electro-optical conversion efficiency of the solid-state light-emitting device replaces the inefficient xenon flash lamp, significantly improving the overall electro-optical conversion efficiency of the device compared to traditional xenon lamps. This significantly increases the number of flashes with the same battery capacity, solving the problem of short battery life in traditional hair removal devices.

Description

Technical Field

[0001] This invention relates to the field of photoelectric beauty technology, and in particular to a pulsed light hair removal device and method based on spectral conversion. Background Technology

[0002] With the rapid development of photoelectric medical aesthetics technology, Intense Pulsed Light (IPL) hair removal devices have become the mainstream equipment in the home and professional hair removal market. These devices emit broadband pulsed light and destroy hair follicle tissue based on the principle of selective photothermolysis to achieve non-invasive hair removal. Due to the huge and continuous growth in demand for hair removal, consumers and medical institutions have put forward higher requirements for the performance indicators of hair removal devices, including higher energy conversion efficiency to extend battery life, longer device lifespan to reduce maintenance costs, smaller device size to improve portability, and more precise spectral control to ensure treatment safety. However, the traditional xenon flash lamp technology, as the core light source component, has reached a bottleneck, and its inherent physical characteristics limit the further improvement of hair removal device performance.

[0003] Existing technologies primarily utilize xenon flash lamps as intense pulsed light sources. The core structure of this approach includes a high-voltage energy storage capacitor, a trigger circuit, and a sealed glass lamp filled with xenon gas. Its working principle involves using a high-voltage electric field to excite xenon atoms, causing ionization and emitting a continuous spectrum covering a wavelength range of 200nm to 2500nm. This spectrum is then filtered to extract the effective therapeutic wavelength range of 500nm to 1200nm. While this technology offers advantages such as high output power and a continuous spectrum, it suffers from six inherent drawbacks that cannot be overcome through engineering optimization: Firstly, the electro-optical conversion efficiency is extremely low, reaching only 15% to 30%, with over 70% of the input electrical energy converted into waste heat. This results in a massive cooling system, severely limiting the equipment's performance. First, the battery life of portable products is limited. Second, the lifespan is limited. During repeated high-voltage discharges, the electrodes of the xenon lamp tube will ablate, and the lamp tube wall will blacken due to deposits, resulting in light output attenuation. Typically, the output power drops by more than 20% after 300,000 flashes, requiring frequent replacement of consumables. Third, the size is large. The xenon lamp tube itself is large and requires a large-capacity energy storage capacitor and a high-voltage reflection cavity. The light source module accounts for more than 60% of the total volume of the treatment head, hindering the miniaturization design of the product. Fourth, the spectral composition is uncontrollable. The full spectrum emitted by the xenon lamp contains a large amount of harmful ultraviolet rays and ineffective far-infrared rays. These ineffective wavelengths are blocked by the filter and are converted into heat, further increasing the heat dissipation burden. Fifth, there is high voltage. Safety concerns include the need for high-voltage capacitor discharge (300V to 450V) to drive xenon lamps, increasing circuit complexity and the difficulty of safety certification; and noise issues, with noticeable popping sounds accompanying the high-voltage discharge process, reducing the user experience. Furthermore, attempts have emerged to use solid-state light-emitting devices (LD) arrays directly as the light source for hair removal, such as the 808nm semiconductor laser hair removal devices widely used in cinemas. This solution utilizes the high electro-optical conversion efficiency (typically over 50%) and long lifespan of solid-state light-emitting devices, arranging multiple laser diode strips into an array to directly emit monochromatic light at a wavelength of 808nm to irradiate the skin. While this technology solves the problems of low efficiency and short lifespan of xenon lamps, its output light is coherent. While intense pulsed light (IPL) hair removal uses light with a single wavelength, the absorption characteristics of melanin in hair follicles vary depending on the wavelength. Broad-spectrum light can more comprehensively cover hair follicles at different growth stages, while single-wavelength lasers mainly target specific melanin absorption peaks, resulting in a relatively narrow treatment window. Furthermore, as a coherent light source, lasers cannot achieve the same uniformity as IPL, easily creating hot spots and increasing the risk of burns. More importantly, under current regulations and industry standards, IPL and lasers are classified as different categories of medical devices with different registration approval pathways and clinical evaluation standards. Directly using laser light sources cannot directly replace existing IPL hair removal devices and cannot meet the market demand for broad-spectrum intense pulsed light treatment.

[0004] Therefore, existing traditional xenon flash lamp light sources have inherent physical defects such as low efficiency, short lifespan, large size, and uncontrollable spectrum. Directly using solid-state light-emitting device arrays, on the other hand, faces problems such as changes in spectral characteristics, poor light spot uniformity, and differences in compliance categories.

[0005] Therefore, it is necessary to provide a pulsed light hair removal device and method based on spectral conversion to solve the above-mentioned technical problems. Summary of the Invention

[0006] This invention provides a pulsed light hair removal device and method based on spectral conversion, which solves the inherent physical defects of traditional xenon flash lamp light sources in the prior art, such as low efficiency, short lifespan, large size, and uncontrollable spectrum. Directly using solid-state light-emitting device arrays also faces problems such as changes in spectral characteristics, poor light spot uniformity, and differences in compliance categories.

[0007] To solve the above-mentioned technical problems, the present invention provides a pulsed light hair removal device based on spectral conversion, comprising: a solid-state light-emitting device, a beam shaping optical component, a spectral conversion layer, a skin contact window, a spectral sensor, and a skin sensor; The solid-state light-emitting device is used to emit narrow-spectrum pump light; The beam-shaping optical component is disposed on the light-emitting path of the solid-state light-emitting device and is used to shape the narrow-spectrum pump light into a uniformly distributed planar light field. The spectral conversion layer is disposed on the light output path of the beam shaping optical component, and is used to absorb the uniformly distributed planar light field and convert it into incoherent broadband pulse light. The skin contact window is located on the light-emitting side of the spectral conversion layer and is used to guide the incoherent broadband pulsed light to the skin surface; The pump light incident surface of the spectral conversion layer is provided with a dichroic film layer. The dichroic film layer has high transmittance of the wavelength of the narrow-spectrum pump light and high reflectance of the wavelength of the incoherent broadband pulse light, and is used to reflect the fluorescence emitted towards the pump light incident surface back to the spectral conversion layer and out from the light emitting surface.

[0008] Preferably, the solid-state light-emitting device is a laser diode bar, and the beam-shaping optical component includes, in sequence along the optical path propagation direction, a fast-axis collimating microlens, a slow-axis collimating microlens array, and a microlens array homogenizer. The fast-axis collimating microlens is disposed in front of the emitting face of the laser diode bar to compress the divergence angle in the fast-axis direction. The slow-axis collimating microlens array corresponds one-to-one with the emitting area of ​​the laser diode bar to compress the divergence angle in the slow-axis direction. The microlens array homogenizer includes two microlens arrays and one Fourier lens to divide and superimpose the collimated beam into a uniform rectangular light field.

[0009] Preferably, the spectral conversion layer is divided into N independent conversion regions, where N is an integer greater than or equal to 2.

[0010] Preferably, the thickness of the spectral conversion layer is gradient-distributed, with the thickness of the edge region being greater than that of the center region, and the edge thickness being greater than the center thickness, in order to compensate for the edge attenuation of the pump light field to achieve uniformity of the output light spot.

[0011] Preferably, the spectral conversion layer is a detachable and replaceable modular structure, which is installed by either magnetic positioning or snap-fit ​​connection; the modular structure integrates a storage unit for storing module type parameters, production date parameters, and usage count values.

[0012] Preferably, the spectral sensor is positioned next to the skin contact window to collect the spectral distribution data of the incoherent broadband pulsed light in real time.

[0013] Preferably, the spectral conversion layer is any one of the following: a fluorescent ceramic sheet containing at least two phosphor components, a composite film containing at least two InP-based cadmium-free quantum dots of different particle sizes, and a rare-earth ion-doped fluorescent glass.

[0014] Preferably, the skin sensor includes at least one of a skin color sensor, a skin contact sensor, a conversion layer temperature sensor, and a skin temperature sensor; the skin color sensor is used to detect skin reflectivity to determine skin color level; the skin contact sensor is used to detect the adhesion state between the skin contact window and the skin; the conversion layer temperature sensor is used to monitor the temperature of the spectral conversion layer; and the skin temperature sensor is used to monitor the skin surface temperature of the treatment area.

[0015] Preferably, the driving circuit of the solid-state light-emitting device is configured to support multiple pulse emission modes, including: a single-pulse rectangular mode and a multi-pulse train mode. The single-pulse rectangular mode outputs a single pulse with a pulse width of 1-100ms. The multi-pulse train mode divides the total energy into multiple sub-pulses, with the interval between adjacent sub-pulses being greater than the skin thermal relaxation time. The power incremental mode linearly increases the pulse power from low to high. The high-frequency low-energy sliding mode emits a pulse sequence with an energy density of 2-3J / cm2 at a frequency of 10-15Hz.

[0016] A pulsed light hair removal method based on spectral conversion, used in the pulsed light hair removal device based on fluorescence conversion or quantum dot conversion, includes the following steps: S1: The solid-state light-emitting device emits narrow-spectrum pump pulse light; S2: The beam-shaping optical component shapes the narrow-spectrum pump pulse light into a uniformly distributed planar light field and illuminates the spectral conversion layer; S3: The spectral conversion layer absorbs the uniformly distributed planar light field and converts it into incoherent broadband pulsed light; S4: The incoherent broadband pulsed light passes through the dichroic film layer and the skin contact window to uniformly irradiate the treatment area over a large area. The dichroic film layer is disposed on the pump light incident surface of the spectral conversion layer, and the dichroic film layer reflects the fluorescence emitted towards the incident surface back to the spectral conversion layer and is emitted from the light emitting surface.

[0017] Compared with related technologies, the pulsed light hair removal device based on spectral conversion provided by the present invention has the following beneficial effects: This invention provides a pulsed light hair removal device based on spectral conversion. By employing a solid-state light-emitting device combined with a spectral conversion layer, the high electro-optical conversion efficiency of the solid-state light-emitting device replaces the inefficient xenon flash lamp, significantly improving the overall electro-optical conversion efficiency compared to traditional xenon lamps. The conversion efficiency of fluorescent ceramics is 60-80%, quantum dot conversion efficiency is 40-60%, and the overall system electro-optical efficiency is 25-40% (vs. xenon lamp 15-30%). This significantly increases the number of flashes with the same battery capacity, solving the problem of short battery life in traditional hair removal devices. Furthermore, by setting a dichroic film layer, the light originally emitted in the direction away from the skin is diverted... Fluorescent light is reflected back to the conversion layer and recycled, improving the overall light extraction efficiency of the spectral conversion layer and effectively solving the problem of lateral emission light loss. This significantly improves energy utilization, thereby reducing the power requirements of the pump light source while ensuring the same treatment energy density. Since solid-state light-emitting devices have a lifespan of hundreds of millions of pulses, far exceeding that of xenon lamps, and the spectral conversion layer uses solid materials such as fluorescent ceramics or quantum dot films, there are no electrode ablation or lamp blackening issues, achieving almost no need to replace consumables throughout the entire lifespan, greatly reducing user maintenance costs and lowering the barrier to entry. A four-step beam homogenization process using fast-axis collimation, slow-axis collimation, and microlens array homogenization is employed. The shaping system transforms the linear beam of the laser diode bar into a highly uniform planar light field, eliminating the inherent "hot spot" effect of lasers and ensuring uniform energy distribution of the output spot. This avoids the risk of skin burns caused by excessive local energy, guaranteeing the safety of hair removal treatment. By dividing the spectral conversion layer into multiple independent regions and employing a time-division multiplexing and alternating excitation strategy, the system cleverly solves the problem of heat accumulation under high-power pumping. This design allows each region sufficient heat dissipation intervals, achieving stable operation without the need for high-power fans or TEC coolers. This makes the device smaller than traditional xenon lamp hair removal devices, greatly improving performance. This enhances the product's portability and user experience; it supports multiple programmable pulse modes such as multi-pulse trains, power increments, and high-frequency sliding, enabling the SHR (Super Hair Removal) mode, which was previously unattainable for home-use devices. It utilizes the difference in epidermal thermal relaxation time for selective photothermal action, significantly reducing pain while ensuring hair removal effectiveness, thus bringing salon-grade treatment capabilities to home-use devices; by integrating a spectral sensor and a closed-loop control algorithm, it can monitor and compensate for spectral drift caused by material aging in real time, ensuring the stability and safety of the output spectrum throughout the device's lifespan, overcoming the defect of uncontrollable attenuation of the spectrum of traditional xenon lamps over time. Attached Figure Description

[0018] Figure 1 A schematic diagram of a pulsed light hair removal device based on spectral conversion provided by the present invention; Figure 2 for Figure 1 A cross-sectional schematic diagram of the beam-shaping optical assembly shown; Figure 3 A schematic diagram of the overall optical path structure of a pulsed light hair removal device based on spectral conversion provided by the present invention; Figure 4 A schematic diagram of a four-step beam shaping optical system for a pulsed light hair removal device based on spectral conversion provided by the present invention; Figure 5 A schematic diagram of multi-region alternating excitation thermal management of a pulsed light hair removal device based on spectral conversion provided by the present invention; Figure 6 A schematic diagram comparing the structures of a traditional xenon lamp IPL and a laser-pumped IPL in a pulsed light hair removal device based on spectral conversion provided by the present invention. Figure 7 A schematic diagram showing the energy density calculation comparison of various pump configurations in a pulsed light hair removal device based on spectral conversion provided by the present invention; Figure 8 This is a schematic flowchart of a pulsed light hair removal device method based on spectral conversion provided by the present invention.

[0019] The following are the labels in the diagram: 1. Solid-state light-emitting device; 2. Beam-shaping optical component; 21. Fast-axis collimating microlens; 22. Slow-axis collimating microlens array; 23. Microlens array homogenizer; 3. Spectral conversion layer; 4. Skin contact window; 5. Dichroic film layer; 6. Spectral sensor. Detailed Implementation

[0020] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0021] Please refer to the following: Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 , Figure 7 and Figure 8 ,in, Figure 1 A schematic diagram of a pulsed light hair removal device based on spectral conversion provided by the present invention; Figure 2 for Figure 1 A cross-sectional schematic diagram of the beam-shaping optical assembly shown; Figure 3 A schematic diagram of the overall optical path structure of a pulsed light hair removal device based on spectral conversion provided by the present invention; Figure 4 A schematic diagram of a four-step beam shaping optical system for a pulsed light hair removal device based on spectral conversion provided by the present invention; Figure 5 A schematic diagram of multi-region alternating excitation thermal management of a pulsed light hair removal device based on spectral conversion provided by the present invention; Figure 6A schematic diagram comparing the structures of a traditional xenon lamp IPL and a laser-pumped IPL in a pulsed light hair removal device based on spectral conversion provided by the present invention. Figure 7 A schematic diagram showing the energy density calculation comparison of various pump configurations in a pulsed light hair removal device based on spectral conversion provided by the present invention; Figure 8 This is a schematic flowchart of a pulsed light hair removal device method based on spectral conversion provided by the present invention.

[0022] A pulsed light hair removal device based on spectral conversion includes: a solid-state light-emitting device 1, a beam shaping optical component 2, a spectral conversion layer 3, a skin contact window 4, a spectral sensor 6, and a skin sensor; The solid-state light-emitting device 1 is used to emit narrow-spectrum pump light; The beam shaping optical component 2 is disposed on the light output path of the solid-state light-emitting device 1 and is used to shape the narrow-spectrum pump light into a uniformly distributed planar light field. The spectral conversion layer 3 is disposed on the light output path of the beam shaping optical component 2, and is used to absorb the uniformly distributed planar light field and convert it into incoherent broadband pulse light. The skin contact window 4 is disposed on the light-emitting side of the spectral conversion layer 3 and is used to guide the incoherent broadband pulsed light to the skin surface. The pump light incident surface of the spectral conversion layer 3 is provided with a dichroic film layer 5. The dichroic film layer 5 has high transmittance of the wavelength of the narrow-spectrum pump light and high reflectance of the wavelength of the incoherent broadband pulse light, and is used to reflect the fluorescence emitted towards the pump light incident surface back to the spectral conversion layer 3 and emitted from the light emitting surface.

[0023] The solid-state light-emitting device 1 is a laser diode bar. The beam-shaping optical component 2 includes, in sequence along the optical path propagation direction, a fast-axis collimating microlens 21, a slow-axis collimating microlens array 22, and a microlens array homogenizer 23. The fast-axis collimating microlens 21 is disposed in front of the emitting face of the laser diode bar to compress the divergence angle in the fast axis direction. The slow-axis collimating microlens array 22 corresponds one-to-one with the emitting area of ​​the laser diode bar to compress the divergence angle in the slow axis direction. The microlens array homogenizer 23 includes two microlens arrays and one Fourier lens to divide and superimpose the collimated beam into a uniform rectangular light field.

[0024] The spectral conversion layer 3 is divided into N independent conversion regions, where N is an integer greater than or equal to 2.

[0025] Each independent conversion area can be driven independently by the control circuit. Based on the skin image recognition results, the area containing hair follicles is selectively activated, while the area where no hair follicles are detected is not activated, thereby achieving precise regional irradiation and reducing ineffective irradiation of non-target skin.

[0026] The thickness of the spectral conversion layer 3 is gradient-distributed, with the thickness of the edge region being greater than that of the center region, and the edge thickness being greater than the center thickness. This is used to compensate for the edge attenuation of the pump light field to achieve uniformity of the output light spot.

[0027] The spectral conversion layer 3 is a detachable and replaceable modular structure. The modular structure can be installed by either magnetic positioning or snap-fit ​​connection. The modular structure integrates a storage unit for storing module type parameters, production date parameters, and usage count values.

[0028] The spectral sensor 6 is disposed next to the skin contact window 4 and is used to collect the spectral distribution data of the incoherent broadband pulse light in real time.

[0029] The spectral conversion layer 3 is any one of the following: a fluorescent ceramic sheet containing at least two phosphor components, a composite film containing at least two InP-based cadmium-free quantum dots of different particle sizes, and a rare earth ion-doped fluorescent glass.

[0030] The skin sensor includes at least one of a skin color sensor, a skin contact sensor, a conversion layer temperature sensor, and a skin temperature sensor; The skin color sensor is used to detect skin reflectivity to determine skin color level; the skin contact sensor is used to detect the adhesion state between the skin contact window 4 and the skin; the conversion layer temperature sensor is used to monitor the temperature of the spectral conversion layer 3; and the skin temperature sensor is used to monitor the skin surface temperature of the treatment area.

[0031] The driving circuit of the solid-state light-emitting device 1 is configured to support multiple pulse emission modes, including: a single-pulse rectangular mode and a multi-pulse train mode. The single-pulse rectangular mode outputs a single pulse with a pulse width of 1-100ms. The multi-pulse train mode divides the total energy into multiple sub-pulses, with the interval between adjacent sub-pulses being greater than the skin thermal relaxation time. The power incremental mode linearly increases the pulse power from low to high. The high-frequency low-energy sliding mode emits a pulse sequence with an energy density of 2-3J / cm² at a frequency of 10-15Hz, while LD Bar+ quantum dots can reach 22J / cm² (cinema-grade).

[0032] The pulsed light hair removal device based on fluorescence conversion or quantum dot conversion is connected to the control circuit. The control circuit is electrically connected to the solid-state light-emitting device 1 and is configured to drive the solid-state light-emitting device 1 corresponding to each independent conversion region in turn in a time-division multiplexing manner, so that the heat dissipation time between two adjacent excitations of any independent conversion region is not less than twice the single excitation time.

[0033] The spectral sensor 6 is controlled by a control unit, which is configured to receive spectral distribution data, compare the measured spectral distribution with a preset target spectral distribution, and adjust the driving power of the solid-state light-emitting device according to the comparison result.

[0034] The control circuit of the skin sensor is configured to: limit the maximum energy density according to the skin color level, prohibit the emission of pump light when the skin is not in contact with the skin, and reduce the power or stop the emission when the temperature exceeds a preset threshold.

[0035] Solid-state light-emitting device 1 serves as a pump source, emitting narrow-spectrum pump light. It features high electro-optical conversion efficiency, long lifespan, small size, and fast response speed. It can also be other solid-state light sources such as VCSEL arrays, high-power LEDs, and superluminescent diodes (SLEDs). Beam-shaping optical component 2 is positioned in the output light path of solid-state light-emitting device 1. Its function is to shape the narrow-spectrum pump light emitted by solid-state light-emitting device 1, which has a large divergence angle and uneven brightness distribution, into a uniformly distributed planar light field. This ensures consistent irradiance at each point in the subsequent spectral conversion layer 3. The spectral conversion layer 3 is positioned in the output light path of beam-shaping optical component 2. Its function is to absorb the shaped uniform pump light and utilize the spontaneous emission effect of fluorescent or quantum dot materials. The light is converted into incoherent broadband pulsed light, the physical properties of which are completely consistent with the intense pulsed light emitted by a traditional xenon lamp. The skin contact window 4 is set on the light-emitting side of the spectral conversion layer 3 to guide the converted incoherent broadband pulsed light to the skin surface for treatment. The pump light incident surface of the spectral conversion layer 3 is provided with a dichroic film layer 5. The dichroic film layer 5 has high transmittance for the wavelength of the narrow-spectrum pump light emitted by the solid-state light-emitting device 1, allowing the pump light to enter the conversion layer efficiently; at the same time, it has high reflectance for the wavelength of the incoherent broadband pulsed light generated by the spectral conversion layer 3, which can reflect the fluorescence originally emitted away from the skin (i.e., the incident surface direction) back to the conversion layer, so that it is finally emitted from the light-emitting surface, thereby significantly improving the overall light extraction efficiency of the light source.

[0036] The solid-state light-emitting device 1 is a laser diode bar. Laser diode bars have the characteristics of linear light-emitting area and high power density, making them suitable as pump sources for large-area intense pulsed light sources. The fast-axis collimating microlens 21 is placed at a very close distance in front of the light-emitting area of ​​the laser diode bar to compress the large divergence angle in the fast-axis direction to a very small angle. The slow-axis collimating microlens array 22 corresponds one-to-one with the emission area of ​​the laser diode bar to compress the divergence angle in the slow-axis direction. The microlens array homogenizer 23 includes two microlens arrays and one Fourier lens. Through the principle of beam splitting and superposition, it shapes the collimated beam into a rectangular light field with a uniformity greater than 95%, eliminating the "hot spot" effect caused by the uneven light emission of the laser diode bar and ensuring the safety and comfort of hair removal treatment.

[0037] The spectral conversion layer 3 is designed as a detachable and replaceable modular structure. This modular structure is installed in the device by magnetic positioning or snap-fit ​​connection, and users can replace it themselves without tools. The modular structure integrates a storage unit, such as an NFC tag or EEPROM, to store module type parameters (such as hair removal, skin rejuvenation, redness reduction, etc.), production date parameters, and usage count values. After reading these parameters, the device's main control system automatically loads the corresponding drive parameters and safety limits, realizing the functional expansion of "one machine for multiple uses".

[0038] To ensure the stability of the output spectrum throughout the device's lifespan, a closed-loop spectral control mechanism is introduced, including a spectral sensor 6 and a control unit. The spectral sensor 6 is located next to the skin contact window 4 and is used to collect spectral distribution data of incoherent broadband pulsed light in real time. The control unit is configured to receive the spectral distribution data, compare the measured spectral distribution with the preset target spectral distribution, and adaptively adjust the driving power of the solid-state light-emitting device 1 according to the comparison results. When a decrease in intensity of a specific wavelength band is detected, compensation is made by increasing the pump power, thereby overcoming the spectral drift problem caused by lamp tube aging in traditional xenon lamp light sources and ensuring the consistency of treatment effects.

[0039] The preferred material for the spectral conversion layer is at least one of a fluorescent ceramic sheet, a quantum dot composite film, or a rare-earth ion-doped fluorescent glass. The fluorescent ceramic sheet contains Ce3+:YAG phosphor components, which have the advantages of good thermal conductivity and strong resistance to light decay. The quantum dot composite film contains InP-based cadmium-free quantum dot components, which have the advantages of a wide spectral tunability range and high conversion efficiency. All of these materials can withstand high-power laser pumping and efficiently convert the pump light into the required broadband light.

[0040] A skin color sensor is used to detect skin reflectivity to determine the Fitzpatrick skin color level, preventing users with dark skin from being burned by excessive energy; a skin contact sensor is used to detect the adhesion between the skin contact window 4 and the skin, ensuring that light is only emitted when fully in contact, avoiding light leakage that could harm the eyes; a conversion layer temperature sensor and a skin temperature sensor are used to monitor the temperature of the light source module and the skin surface, respectively. Once the temperature exceeds the safety threshold, the emission will stop immediately. The control circuit executes the corresponding safety interlock logic based on the feedback signals from the above sensors, ensuring user safety in all aspects.

[0041] Leveraging the fast response speed of the solid-state light-emitting device 1, the pulse waveform is fully programmable. The driving circuit of the solid-state light-emitting device 1 is configured to support multiple pulse emission modes, including single-pulse rectangular mode, multi-pulse train mode, power incremental mode, and high-frequency low-energy sliding mode. Among them, the multi-pulse train mode divides the total energy into multiple sub-pulses, and the interval between sub-pulses is designed to be greater than the epidermal thermal relaxation time but less than the hair follicle thermal relaxation time. Utilizing the principle of selective photothermolysis, while ensuring the hair follicle destruction effect, it allows the epidermis to cool during the pulse interval, significantly reducing pain. The high-frequency low-energy sliding mode (SHR mode) supports emission at a frequency of 10-15Hz. When used with the treatment head to slide on the skin, it achieves fast and painless hair removal, bringing the functions previously only available in professional equipment to home-use models.

[0042] In a preferred embodiment of the present invention, the solid-state light-emitting device 1 is a laser diode bar. A laser diode bar is a semiconductor device that integrates multiple laser emitting units on a single substrate. Its standard size is typically 10mm × 1mm, and it has extremely high power density. The laser diode bar contains 19 to 49 independent emitting regions, each with a light-emitting width of approximately 100-200μm, and the spacing between the emitting regions is approximately 200-500μm. For electrical connection, the laser diode bar is mounted on a copper heat sink via gold wire bonding or sintering. The heat sink is further connected to the device's heat dissipation system via thermally conductive silicone grease or heat pipes to quickly dissipate waste heat generated during operation. The driving end of the laser diode bar is electrically connected to the driving circuit in the control circuit via wires. The driving circuit is designed in a constant current pulse driving mode and can provide a peak current of 40A. The reason for choosing a laser diode bar instead of a single edge-emitting laser is that the pulse current is adjustable from 1ms to 100ms, up to 120A. The bar structure provides higher power density within a single linear length, is easier to shape into a linear spot by subsequent optical systems, and then convert it into a planar spot. It is also more cost-effective than a single laser array. The center emission wavelength of the laser diode bar is preferably 808nm±5nm, and the pump wavelength can be selected as 450nm (blue light pumping YAG), 808nm (near-infrared pumping), or 940nm (InGaAs pumping), covering more technical routes. This wavelength is located in the band where solid-state light-emitting devices are most efficient and can be efficiently absorbed by commercially available fluorescent materials (such as Ce3+:YAG).

[0043] Since the light emission characteristics of the laser diode bar are linear light sources, and it has a large divergence angle (about 30° to 40° half-angle) in the fast axis direction (perpendicular to the junction plane) and a small divergence angle (about 5° to 10° half-angle) in the slow axis direction (parallel to the junction plane), if it directly irradiates the spectral conversion layer 3, it will cause the light intensity distribution on the conversion layer to be extremely uneven, with overheating at the center and insufficient energy at the edges. Therefore, a four-step beam shaping system was designed. The beam shaping optical component 2 includes, in sequence along the optical path propagation direction, a fast axis collimating microlens 21, a slow axis collimating microlens array 22, and a microlens array homogenizer 23.

[0044] The fast-axis collimating microlens 21 is positioned at an extremely close distance of 0.3 mm to 0.8 mm in front of the light-emitting line of the laser diode bar. This lens is typically a cylindrical microlens made of high-refractive-index glass (such as H-ZLaF92), with a focal length of 0.5 mm to 1 mm and a numerical aperture (NA) greater than 0.6, to match the fast-axis divergence angle of the laser diode bar. The function of the fast-axis collimating microlens 22 is to compress the large divergence angle in the fast-axis direction to nearly parallel light of 0.3° to 0.5°. During the packaging stage, its position is adjusted by an active alignment process to make its generatrix parallel to the light-emitting line of the laser diode bar, and then cured with UV adhesive.

[0045] The slow-axis collimating microlens array 23 is located behind the fast-axis collimating microlens 21. This component consists of multiple independent cylindrical microlenses or an integrated lens array plate. Each cylindrical microlens unit corresponds to one emission region of the laser diode bar. The function of the slow-axis collimating microlens array 22 is to compress the divergence angle of each emission region in the slow axis direction to 0.5° to 1°. Through the two-stage collimation of the fast and slow axes, the diverging beam emitted by the laser diode bar is shaped into a nearly parallel linear beam. However, at this time, the light intensity distribution of the beam on the cross section still exhibits a Gaussian distribution characteristic of being bright in the middle and dark at the edges, and the dark stripes between the emission regions are retained.

[0046] The microlens array homogenizer 23 is located behind the slow-axis collimating microlens array 22 and is a key component for achieving uniform surface illumination. The microlens array homogenizer 23 includes a first microlens array, a second microlens array, and a Fourier lens. The first and second microlens arrays are arranged parallel to each other and spaced apart. The second microlens array is located on the focal plane of the first microlens array, and the Fourier lens is located behind the second microlens array. Its focal plane is the final target illumination surface (i.e., the incident surface of the spectral conversion layer 30). The collimated linear beam first enters the first microlens array, which consists of multiple rectangular aperture sub-lenses. Each sub-lens focuses the beam incident upon it into a spot. The sub-lenses of the second microlens array correspond one-to-one with the sub-lenses of the first microlens array and have the same aperture. Their function is to focus the beam focused by the first microlens array. Collimation is performed to convert the light beams into parallel beams with different tilt angles. Fourier lenses converge these parallel beams with different tilt angles onto their focal plane. According to the Fourier optical principle, the light intensity distribution on the focal plane is the Fourier transform of the incident light field angular spectrum. Since the first microlens array divides the beam into N×M sub-beams, these sub-beams superimpose on the focal plane after passing through the Fourier lens. According to statistical principles, the superposition of a large number of random phase sub-beams will lead to a more uniform light intensity distribution. By precisely designing the shape of the sub-lenses of the microlens array (such as rectangles) and the focal length of the Fourier lens, a rectangular uniform light spot with a size of 10mm×20mm and a uniformity greater than 95% can be formed on the surface of the spectral conversion layer 3. The design parameters of the microlens array homogenizer 23 must meet the optical parameter product (BPP) matching principle to ensure the highest light energy utilization.

[0047] The geometry of the spectral conversion layer 3 is designed to match the size of the beam spot after beam shaping, for example, a rectangular sheet of 10mm × 20mm with a thickness ranging from 0.3mm to 1.0mm. To optimize light extraction efficiency, the spectral conversion layer 3 has a special film structure. A dichroic film layer 5 is deposited on the pump light incident surface of the spectral conversion layer 3 (i.e., the surface facing the solid-state light-emitting device 1). The optical properties of the dichroic film layer 5 are designed as follows: it has a high transmittance of more than 95% for pump light with a wavelength of 808nm, allowing the pump light to enter the interior of the conversion layer without loss; at the same time, it has a high reflectance of more than 80% for fluorescence in the 500nm to 700nm band. Since the fluorescence generated by the excited fluorescent material is emitted into the entire space at a solid angle of 4π, approximately 50% of the fluorescence is emitted into the solid angle of 4π. The fluorescence is emitted in the direction away from the skin (i.e., the direction of the incident surface). Without the dichroic film layer 5, this part of the light would be lost. The dichroic film layer 5 reflects this back-emitted fluorescence back into the conversion layer, so that it is finally emitted from the light-emitting surface after multiple scatterings, thereby improving the light extraction efficiency by 30% to 40%. An anti-reflection film is coated on the light-emitting surface (i.e. the surface facing the skin) of the spectral conversion layer 3. The anti-reflection film is a MgF2 single-layer film or a SiO2 / TiO2 multilayer dielectric film, which is used to reduce the total internal reflection loss of fluorescence at the light-emitting interface and further improve the light extraction efficiency.

[0048] To address the heat accumulation problem of the spectral conversion layer 3 under high-power pumping, this invention proposes a multi-region alternating excitation thermal management strategy. The spectral conversion layer 3 is physically divided into N independent conversion regions (preferably N=4), labeled as region A, region B, region C, and region D. Each independent conversion region corresponds to a set of independent solid-state light-emitting devices 1 and beam-shaping optical components 2. The control circuit is configured to control the emission timing of each group of lasers in a time-division multiplexing (TDM) manner. The specific timing sequence is as follows: In the first time slot (e.g., 0-10ms), the control circuit only drives the laser corresponding to region A to emit, and region A outputs strong pulsed light. At this time, regions B, C, and D are in a heat dissipation state; in the second time slot (… (10-20ms), the control circuit only drives the laser corresponding to region B to emit, while region A stops working and begins to dissipate heat; and so on. Through this time-division multiplexing strategy, the heat dissipation time interval between two adjacent excitations of any independent conversion region is not less than 3 times the single excitation time, thereby effectively suppressing the heat accumulation effect. For example, if the single pulse width is 10ms and 4-region time-division operation is adopted, each region has a 30ms heat dissipation interval. Thermal simulation results show that under the same average power output, this strategy can reduce the peak temperature of the conversion layer by about 40%, so that the system only needs to rely on the aluminum substrate and natural convection heat dissipation to meet the requirements, without the need for TEC coolers or fans, significantly reducing the size of the device and reducing noise.

[0049] To compensate for the natural attenuation of the pump light field edge energy, the spectral conversion layer 3 adopts a thickness gradient compensation design. The thickness of the spectral conversion layer 3 is distributed in a gradient from the center to the edge, with the edge region being about 5% to 15% thicker than the center region. Since the light field after being shaped by the microlens array homogenizer 23 usually has a slightly lower energy density at the edge than at the center (about 5%-10%), by increasing the material thickness of the edge region, it can absorb more pump light and generate more fluorescence, thereby compensating for the non-uniformity of the pump light field and ultimately achieving an output spot uniformity greater than 97%.

[0050] Regarding the skin contact window 4, it is made of sapphire material. Sapphire has extremely high hardness (Mohs hardness 9), is wear-resistant, and has extremely high light transmittance in the visible to near-infrared band (transmittance >95%). The thickness of the sapphire window is set to 1.0mm to 2.0mm to ensure sufficient mechanical strength and facilitate heat conduction. The outer side of the sapphire window (the side in contact with the skin) is usually coated with an anti-reflection film to reduce interface reflection loss. In practical applications, the sapphire window also has a contact cooling function. It is connected to the heat sink inside the device through thermally conductive adhesive, which can quickly remove heat from the skin surface and reduce pain during treatment.

[0051] Regarding the control circuit and sensing components, the control circuit includes a microcontroller (MCU), a laser drive circuit, a signal acquisition circuit, and a power management circuit; the sensing components include a skin color sensor, a skin contact sensor, a conversion layer temperature sensor, and a skin temperature sensor; the skin color sensor is located beside the skin contact window 4 and uses RGB... The combination of LEDs and photodiodes detects the intensity of reflected light on the skin surface, calculates skin reflectivity, and then determines the user's Fitzpatrick skin tone level (I-VI). The MCU automatically sets the maximum allowable energy density based on the skin tone level. For example, for users with dark skin tones of IV-VI, the energy density is limited to no more than 3J / cm2 to prevent burns. The skin contact sensor is a capacitive sensor located inside the treatment head shell to detect whether the treatment head is in close contact with the skin. The MCU only unlocks the laser emission function when a skin contact signal is detected to prevent light leakage from harming the eyes. The conversion layer temperature sensor uses a miniature NTC thermistor, installed close to the side of the spectral conversion layer 30, to monitor the conversion layer temperature in real time. If the temperature exceeds a safety threshold (e.g., 80°C), the MCU automatically reduces the laser power or stops emission. The skin temperature sensor uses a non-contact infrared thermometer chip (e.g., MLX90614), located inside the sapphire window, to measure the skin surface temperature through the sapphire. If the skin temperature exceeds 42°C, the MCU pauses treatment and prompts for cooling. The collaborative work of multiple sensors constitutes a comprehensive safety interlock protection mechanism.

[0052] This invention also provides a modular and replaceable design, with the spectral conversion layer 3 encapsulated as an independent modular structure. This modular structure includes a fluorescent ceramic sheet or quantum dot film, a cutoff filter, and an NFC tag. The modular structure is detachably installed inside the treatment head via a magnetic positioning component and a spring-loaded clamping component. The magnetic positioning component ensures precise and repeatable positioning of the module, while the spring-loaded clamping component ensures tight contact between the module and the heat dissipation substrate and optical system. The NFC tag stores module type parameters (such as "standard hair removal module" or "skin rejuvenation module"), production date parameters, and the number of pulses used. When the user replaces the module, the device automatically reads the NFC information and loads the corresponding drive parameters, achieving "one device, multiple uses."

[0053] In another embodiment, a galvanometer scanning method can be used instead of a microlens array homogenizer to achieve beam orientation.

[0054] The working principle of the pulsed light hair removal device based on spectral conversion provided by this invention is as follows: When in operation, after the user starts the device and selects the treatment mode, the device first performs a self-test. The MCU reads the data from the temperature sensor of the conversion layer to confirm that the temperature of the spectral conversion layer 3 is normal; it reads the NFC tag information to confirm that the module type matches. Then, the user places the treatment head against the skin. The skin contact sensor detects the contact signal and unlocks the emission function. The skin color sensor emits a light beam and receives the skin reflection signal. The MCU calculates the skin color level and sets the energy density limit.

[0055] Subsequently, the user presses the launch button, and the MCU controls the drive circuit to output a current pulse. The current pulse flows through the laser diode bar, exciting it to emit an 808nm pulsed laser. After being collimated by the fast-axis collimating microlens 21 and the slow-axis collimating microlens array 22, the laser beam becomes a nearly parallel line beam. This beam enters the microlens array homogenizer 23, is divided and superimposed, and finally forms a uniform rectangular spot on the incident surface of the spectral conversion layer 3.

[0056] The fluorescent material in the spectral conversion layer 3 absorbs the 808nm pump light energy, and the electrons transition to the excited state. Then, through spontaneous emission, they transition back to the ground state and emit incoherent broadband fluorescence with a wavelength range of 500nm to 1200nm. The dichroic film layer 5 reflects the back-emitted fluorescence back to the conversion layer, so that it is finally emitted from the light-emitting surface. After the emitted broadband light passes through the cutoff filter to remove the residual 808nm laser and unwanted short-wavelength light, it passes through the sapphire skin contact window 4 and irradiates the skin surface.

[0057] During the emission process, the spectral sensor 6 collects the spectral distribution data of the output light in real time. If a decrease in intensity is detected in a specific band (indicating aging of the fluorescent material), the MCU automatically increases the driving current to compensate for the energy. At the same time, the skin temperature sensor monitors the skin surface temperature in real time. Once the temperature exceeds the limit, the emission stops immediately. If a multi-region rotation excitation mode is adopted, the MCU drives the lasers corresponding to regions A, B, C, and D in sequence according to a preset timing to achieve thermal management. After the treatment is completed, the MCU updates the pulse count value in the NFC tag.

[0058] Compared with related technologies, the pulsed light hair removal device based on spectral conversion provided by the present invention has the following beneficial effects: This invention provides a pulsed light hair removal device based on spectral conversion. By employing a solid-state light-emitting device 1 combined with a spectral conversion layer, the high electro-optical conversion efficiency of the solid-state light-emitting device 1 replaces the inefficient xenon flash lamp, significantly improving the overall electro-optical conversion efficiency compared to traditional xenon lamps. This results in a significantly increased number of flashes with the same battery capacity, solving the problem of short battery life in traditional hair removal devices. Furthermore, by setting a dichroic film layer 5, fluorescence originally emitted away from the skin is reflected back to the conversion layer and recycled, improving the overall light extraction efficiency of the spectral conversion layer 3 and effectively solving the problem of light loss due to lateral emission. The problem of energy loss is significantly improved, thus reducing the power requirements of the pump light source while ensuring the same treatment energy density. Because solid-state light-emitting devices have a lifespan of hundreds of millions of pulses, far exceeding that of xenon lamps, and because the spectral conversion layer 3 uses solid materials such as fluorescent ceramics or quantum dot films, there are no electrode ablation or lamp blackening issues, achieving almost no need to replace consumables throughout the entire lifespan, significantly reducing user maintenance costs and lowering the barrier to entry. Through a four-step beam shaping system employing fast-axis collimation, slow-axis collimation, and microlens array homogenization, the linear beam of the laser diode bar is transformed into a beam with excellent uniformity. The planar light field eliminates the inherent "hot spot" effect of lasers, ensuring uniform energy distribution of the output spot and avoiding the risk of skin burns caused by excessive local energy, thus guaranteeing the safety of hair removal treatment. By dividing the spectral conversion layer 3 into multiple independent regions and adopting a time-division multiplexing and alternating excitation strategy, the problem of heat accumulation under high-power pumping is cleverly solved. This design allows each region to have sufficient heat dissipation intervals, achieving stable operation without the need for high-power fans or TEC coolers. This makes the device smaller than traditional xenon lamp hair removal devices, greatly improving the product's portability and user experience. It supports multiple programmable pulse modes such as multi-pulse train, power increment, and high-frequency sliding, realizing the SHR (Super Hair Removal) mode that was previously impossible for home devices. It utilizes the difference in epidermal thermal relaxation time for selective photothermal action, significantly reducing pain while ensuring hair removal effect, and bringing the treatment capabilities of the clinic to home devices. By integrating a spectral sensor 6 and a closed-loop control algorithm, it can monitor and compensate for spectral drift caused by material aging in real time, ensuring the stability and safety of the output spectrum throughout the device's entire life cycle, and overcoming the defect of uncontrollable decay of the spectrum of traditional xenon lamps over time.

[0059] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A pulsed light hair removal device based on spectral conversion, characterized in that include: Solid-state light-emitting devices, spectral conversion layers, and skin contact windows; The solid-state light-emitting device is used to emit narrow-spectrum pump light; The spectral conversion layer is disposed on one side of the solid-state light-emitting device and is used to absorb the light field and convert it into incoherent broadband pulsed light; The skin contact window is located on the light-emitting side of the spectral conversion layer and is used to guide incoherent broadband pulsed light to the skin surface.

2. The pulsed light hair removal device based on spectral conversion according to claim 1, characterized in that, The solid-state light-emitting device is provided with a beam-shaping optical component in the light output path. The solid-state light-emitting device includes, but is not limited to, any one of a laser diode, a vertical-cavity surface-emitting laser, a laser diode bar, a high-power LED, and a superluminescent diode.

3. The pulsed light hair removal device based on spectral conversion according to claim 1, characterized in that, The vertical cavity surface-emitting laser array serves as the pump source.

4. The pulsed light hair removal device based on spectral conversion according to claim 1, characterized in that, The pump light incident surface of the spectral conversion layer is provided with a dichroic film layer. The dichroic film layer has high transmission of the wavelength of the narrow-spectrum pump light and high reflection of the wavelength of the incoherent broadband pulse light. It is used to reflect the fluorescence emitted towards the pump light incident surface back to the spectral conversion layer and out of the light emitting surface, and to shape the narrow-spectrum pump light into a uniformly distributed planar light field.

5. The pulsed light hair removal device based on spectral conversion according to claim 1, characterized in that, The beam-shaping optical component includes, in sequence along the optical path propagation direction, a fast-axis collimating microlens, a slow-axis collimating microlens array, and a microlens array homogenizer. The fast-axis collimating microlens is positioned in front of the emitting area of ​​the solid-state light-emitting device to compress the divergence angle in the fast-axis direction. The slow-axis collimating microlens array corresponds one-to-one with the emitting area of ​​the solid-state light-emitting device to compress the divergence angle in the slow-axis direction. The microlens array homogenizer includes two microlens arrays and one Fourier lens to divide and superimpose the collimated beam into a uniform rectangular light field.

6. The pulsed light hair removal device based on spectral conversion according to claim 1, characterized in that, The spectral conversion layer is divided into N independent conversion regions, where N is an integer greater than or equal to 2.

7. The pulsed light hair removal device based on spectral conversion according to claim 1, characterized in that, The thickness of the spectral conversion layer is gradient-distributed, with the thickness of the edge region being greater than that of the center region, and the edge thickness being greater than the center thickness. This is used to compensate for the edge attenuation of the pump light field to achieve uniformity of the output light spot.

8. The pulsed light hair removal device based on spectral conversion according to claim 1, characterized in that, The spectral conversion layer is a detachable and replaceable modular structure, which can be installed by either magnetic positioning or snap-fit ​​connection. The modular structure integrates a storage unit for storing module type parameters, production date parameters, and usage count values.

9. A pulsed light hair removal device based on spectral conversion according to claim 1, characterized in that, A spectral sensor is provided next to the skin contact window to collect the spectral distribution data of the incoherent broadband pulsed light in real time, and a skin sensor is provided on the other side of the skin contact window.

10. A pulsed light hair removal device based on spectral conversion according to claim 1, characterized in that, The spectral conversion layer is any one of the following: a fluorescent ceramic sheet containing at least two phosphor components, a composite film containing at least two InP-based cadmium-free quantum dots of different particle sizes, and a rare-earth ion-doped fluorescent glass.

11. A pulsed light hair removal device based on spectral conversion according to claim 8, characterized in that, The skin sensor includes at least one of a skin color sensor, a skin contact sensor, a conversion layer temperature sensor, and a skin temperature sensor; the skin color sensor is used to detect skin reflectivity to determine skin color level; the skin contact sensor is used to detect the adhesion state between the skin contact window and the skin; the conversion layer temperature sensor is used to monitor the temperature of the spectral conversion layer; and the skin temperature sensor is used to monitor the skin surface temperature of the treatment area.

12. The pulsed light hair removal device based on spectral conversion according to claim 1, characterized in that, The driving circuit of the solid-state light-emitting device is configured to support multiple pulse emission modes, including: a single-pulse rectangular mode and a multi-pulse train mode. The single-pulse rectangular mode outputs a single pulse with a pulse width of 1-100ms. The multi-pulse train mode divides the total energy into multiple sub-pulses, with the interval between adjacent sub-pulses being greater than the skin thermal relaxation time. The power incremental mode increases the pulse power linearly from low to high. The high-frequency low-energy sliding mode emits a pulse sequence with an energy density of 2-3J / cm2 at a frequency of 10-15Hz.

13. A pulsed light hair removal method based on spectral conversion, used in the pulsed light hair removal device based on fluorescence conversion or quantum dot conversion as described in any one of claims 1-11, characterized in that, Includes the following steps: S1: The solid-state light-emitting device emits narrow-spectrum pump pulse light; S2: The spectral conversion layer absorbs the light field and converts it into incoherent broadband pulsed light; S3: The incoherent broadband pulsed light passes through the dichroic film layer and the skin contact window to uniformly irradiate the treatment area over a large area.

14. The pulsed light hair removal method based on spectral conversion according to claim 13, characterized in that, The dichroic film layer is disposed on the pump light incident surface of the spectral conversion layer. The dichroic film layer reflects the fluorescence emitted towards the incident surface back to the spectral conversion layer and is emitted from the light emitting surface.

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