Pulsed light hair removal system based on spectrum conversion and control method thereof

Abstract

The invention discloses a pulsed light hair removal system based on spectrum conversion and a control method thereof. The system comprises a pump light source module, a spectrum conversion module, an image acquisition module and a processor. The system provided by the invention has a pixel-level accurate control capability, the accuracy is greatly improved compared with the traditional IPL, and pixel-level energy self-adaption is realized, so that personalized treatment is supported. The system also supports sliding continuous irradiation, can greatly shorten the treatment time, has the advantages of high energy efficiency ratio, small invalid irradiation area, low pain feeling and the like, and can effectively reduce unnecessary thermal stimulation.

Description

Technical Field

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

[0002] There are two main types of light sources in the field of optical hair removal. The first type is intense pulsed light (IPL), which uses a xenon flash tube to generate a broad-spectrum incoherent pulsed light. Its advantages are that the broad spectrum covers multiple target chromophores, good safety, and a lower regulatory classification. Its disadvantages are that the light spot is large, it cannot accurately locate individual hair follicles, and the energy utilization rate is low. The second type is laser, which uses a semiconductor laser to generate single-wavelength coherent light. Its advantages are that the energy is concentrated and precise positioning can be achieved through a galvanometer. Its disadvantages are that the single wavelength has poor adaptability to different skin tones or hair colors, a higher regulatory classification, a longer registration period, and higher costs.

[0003] Therefore, there is a contradiction between precision and regulatory compliance in existing technologies: precise hair removal requires lasers, while low-regulatory-category IPL (Intense Pulsed Laser) cannot achieve precise targeting. Currently, there is no solution in the industry that can simultaneously achieve both precision and IPL compliance. Summary of the Invention

[0004] The purpose of this invention is to provide a pulsed light hair removal system based on spectral conversion and its control method, thereby solving the problems in the background art.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A pulsed light hair removal system based on spectral conversion, comprising:

[0007] A pump light source module, wherein the pump light source module is an array composed of multiple independently controllable laser diodes;

[0008] A spectral conversion module is located in front of the light-emitting front of the pump light source module. It is used to absorb the laser emitted by the laser diode and convert it into incoherent broadband pulsed light through spontaneous emission.

[0009] The image acquisition module is used to acquire skin images;

[0010] The processor, connected to the image acquisition module and the pump light source module respectively, is used to generate control signals to independently control the on / off state of the lasers at corresponding positions in the laser diode array based on the hair follicle positions in the skin image, so as to achieve pixel-level precise irradiation.

[0011] Furthermore, the spectral conversion module is internally equipped with an opaque isolation structure, which divides the spectral conversion module into multiple independent conversion regions corresponding one-to-one with the laser diode array, in order to suppress fluorescence lateral diffusion and maintain pixel-level spatial accuracy.

[0012] Furthermore, the opaque isolation structure can be one of the following:

[0013] Method 1: A metal mesh groove running through the entire thickness of the spectral conversion module, the mesh groove being filled with an opaque material;

[0014] Method 2: A discrete fluorescent material dot array formed on a transparent substrate by printing or photolithography, wherein the spacing of the fluorescent material dot array matches the spacing of the laser diode array;

[0015] Method 3: An optical fiber bundle consisting of multiple closely arranged optical fibers, with the core of each fiber filled with fluorescent or quantum dot materials.

[0016] Furthermore, it also includes a skin color sensor and a skin temperature sensor. The processor is connected to the skin color sensor and the skin temperature sensor respectively, and is used to automatically limit the maximum output energy density according to the Fitzpatrick skin color level determined by the skin color sensor, and to automatically reduce the energy or stop irradiation when the temperature exceeds a preset threshold according to the reading of the skin temperature sensor.

[0017] Furthermore, the spectral conversion module is a detachable and replaceable modular structure, which is installed in the treatment head by magnetic attraction or snap-fit; different modules correspond to different fluorescent material formulations and cutoff filter combinations; the module integrates an NFC tag for storing module type and usage count information.

[0018] Furthermore, the spectral conversion module is a fluorescence conversion layer or a quantum dot conversion layer. The fluorescence conversion layer contains at least two phosphors with different emission wavelengths, and the quantum dot conversion layer contains at least two semiconductor quantum dots with different particle sizes, so that the output spectrum covers the 500-1200nm range.

[0019] Furthermore, the semiconductor quantum dots in the quantum dot conversion layer are InP-based or CuInS2-based cadmium-free quantum dots.

[0020] Furthermore, the output light of the spectral conversion module is incoherent light, the spectral half-width of which is greater than 200 nm, and it is emitted in a pulsed manner.

[0021] Furthermore, the control signal is a lighting vector corresponding to the laser diode array, and each element in the lighting vector is independently set to zero or a specific energy parameter. The energy parameter is determined according to the diameter or number of hair follicles in the corresponding pixel area to achieve adaptive energy control.

[0022] Furthermore, the hair removal system also includes an inertial measurement unit for real-time detection of the motion state of the treatment head. The processor updates the control signal and adjusts the pulse emission frequency in real time based on the motion state to support a sliding continuous irradiation mode.

[0023] Furthermore, a microlens array is provided between the pump light source module and the spectral conversion module. The microlens array corresponds one-to-one with the laser diode and is used to collimate the diverging beam of each laser and project it onto the corresponding area on the spectral conversion module to reduce optical crosstalk.

[0024] Furthermore, an ultraviolet cutoff filter and a heat-conducting window are sequentially arranged behind the spectral conversion module. The ultraviolet cutoff filter is used to filter out ultraviolet light, and the heat-conducting window is used to transmit therapeutic light and conduct heat.

[0025] A pulsed light hair removal method based on spectral conversion, applied to the aforementioned pulsed light hair removal system based on spectral conversion, includes the following steps:

[0026] Acquire skin images;

[0027] Identify hair follicle coordinates from the skin image;

[0028] The hair follicle coordinates are mapped to the pixel grid of the laser diode array to generate control signals for controlling the independent on / off state of each laser.

[0029] According to the control signal, the corresponding laser is selectively driven to emit pump light pulses;

[0030] The pump light pulse excitation spectrum conversion module converts the light into incoherent broadband pulse light and outputs it to the skin surface.

[0031] Furthermore, the energy parameter in the control signal is calculated and determined based on at least one of the following factors: the diameter and number of hair follicles in the corresponding pixel area, and the user's skin color type.

[0032] Beneficial effects:

[0033] The system in this invention possesses pixel-level precision control capabilities, significantly improving accuracy compared to traditional IPL, and achieves pixel-level energy adaptation, thereby supporting personalized treatment. Furthermore, this system supports continuous sliding irradiation, which can greatly shorten treatment time, while also offering advantages such as high energy efficiency, small ineffective irradiation area, and low pain, effectively reducing unnecessary thermal stimulation. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the system structure of the present invention;

[0035] Figure 2 This is a top view of the VCSEL array and a schematic diagram of selective illumination in this invention;

[0036] Figure 3 This is a schematic diagram of the microstructure and conversion principle of the fluorescence conversion layer in this invention;

[0037] Figure 4 This is a comparison chart of the output spectra in this invention;

[0038] Figure 5 This is a flowchart of the AI ​​visual recognition and control process in this invention;

[0039] Figure 6 This is a flowchart of the control method in this invention. Detailed Implementation

[0040] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0041] Example 1

[0042] like Figure 1 As shown, the hair removal system in this embodiment includes a pump light source module, a microlens array, a spectral conversion module, an ultraviolet cutoff filter, a sapphire thermal window, an image sensor, and an embedded processor.

[0043] like Figure 2 As shown, the pump source module is an 8×8 vertical-cavity surface-emitting laser (VCSEL) array chip, totaling 64 chips, packaged on the same heat sink substrate. Each VCSEL emits at a wavelength of 808nm, with a peak pulse power of 5W, an array spacing of 1.5mm, and a total size of 12mm×12mm. Each VCSEL is equipped with an independent MOSFET driver switch, controlled individually by an embedded processor via a shift register or GPIO expander. The pulse width is determined by the high-level duration of the drive signal and can be arbitrarily set within the range of 0.1-50ms.

[0044] A microlens array is set 0.5 mm in front of the VCSEL array, corresponding one-to-one with the VCSELs, to collimate the diverging beam of each VCSEL into near-parallel light and project it onto the corresponding area on the spectral conversion module, thereby reducing optical crosstalk.

[0045] The spectral conversion module is positioned 0.5 mm in front of the VCSEL array's output light-emitting surface. In this embodiment, it is in the form of a fluorescent ceramic sheet. The fluorescent ceramic sheet is a dense ceramic sheet sintered from phosphor, with a thickness of 0.8 mm. The spectral conversion module contains an opaque isolation structure that divides it into multiple independent conversion regions corresponding one-to-one with the VCSEL array. This is used to suppress lateral fluorescence diffusion and maintain pixel-level spatial accuracy. Specifically, this embodiment uses a metal mesh groove that runs through the entire thickness of the fluorescent ceramic sheet. Each mesh groove corresponds one-to-one with a VCSEL pixel, and the groove is filled with an opaque material, such as silver paste or a black light-absorbing polymer, forming an optical barrier to ensure clear boundaries of the output light spot in each pixel region.

[0046] As an alternative to the opaque isolation structure, this embodiment also provides two other implementation methods: Method 2: Using a discrete fluorescent material dot array formed on a transparent substrate by printing or photolithography, the spacing of the fluorescent material dot array matches the spacing of the VCSEL array, and the air gap between the dots plays an isolation role; Method 3: Using an optical fiber bundle composed of multiple optical fibers arranged closely together, with the core of each optical fiber filled with fluorescent material, and the optical fiber cladding serving as a natural opaque isolation structure.

[0047] like Figure 3 As shown, the phosphor formulation is optimized for an 808nm pump wavelength, and the specific components are shown in Table 1:

[0048] Table 1

[0049]

[0050] like Figure 4 As shown, the 808nm photons emitted by the VCSEL are absorbed by the phosphors and converted into incoherent fluorescence through spontaneous emission. The emission spectra of each phosphor are superimposed to form a broadband pulse light with a full width at half maximum (FWHM) greater than 200nm, and emitted in a pulsed manner. Curve (a) is the 808nm pump spectrum, with a center wavelength of 808nm and a FWHM of approximately 3nm. Curve (b) is the output spectrum after fluorescence conversion, where the emission peak at 410 corresponds to Ce. 3+ YAG (~550nm), emission peak 411 corresponds to Eu 2+ CASN (~630nm), emission peak 412 corresponds to Nd 3 + YAG (~1064nm), when combined, covers the effective hair removal range of IPL from 500-1200nm.

[0051] The spectral conversion module features a detachable and replaceable modular structure, installed inside the treatment head via magnetic attraction or snap-fit. Different modules correspond to different fluorescent material formulations and cutoff filter combinations. For example, modules designed for darker skin tones reduce long-wavelength penetration depth and are paired with more efficient UV cutoff filters, while modules for lighter hair enhance energy density near the melanin absorption peak. Each module integrates an NFC tag that stores the module type, manufacturing date, and cumulative usage count. After installation, the processor reads the tag information via an NFC reader, automatically invokes the corresponding energy control algorithm, and prompts the user to replace the module when the usage count exceeds its rated lifespan.

[0052] A UV cutoff filter and a sapphire thermally conductive window are sequentially placed after the spectral conversion module. The UV cutoff filter is used to filter out UV fluorescence components with wavelengths less than 500nm. The sapphire thermally conductive window, with a thickness of 1-3mm, combines optical transmission and thermal conduction functions to transmit therapeutic light and conduct heat.

[0053] The image acquisition module and the light source module are installed side-by-side inside the treatment head for real-time acquisition of skin surface images. An embedded processor connects to the image acquisition module and the drive circuit, executing the following control logic: The processor runs a hair follicle detection algorithm, outputting a set of hair follicle coordinates {(x_i, y_i, d_i)} from the skin image, where d_i is the estimated diameter of the i-th hair follicle; then, the hair follicle coordinates are mapped to an 8×8 VCSEL pixel grid, generating a illumination vector L[p][q] (p, q = 1..8). Pixels without hair follicles have L[p][q] = 0, and pixels with hair follicles have L[p][q] = f(d_i), where f is an energy calculation function. The optimal pulse energy is output based on the hair follicle diameter, thereby achieving pixel-level precise irradiation.

[0054] The system also includes a skin color sensor and a skin temperature sensor, both connected to the processor. The skin color sensor detects the user's skin color in real time before or during treatment and converts it into a Fitzpatrick skin type level. The skin temperature sensor monitors the epidermal temperature of the irradiated area in real time. The processor automatically limits the maximum output energy density based on the skin color level. Simultaneously, when the temperature exceeds a preset safety threshold, the processor automatically reduces the energy of subsequent pulses or pauses irradiation until the temperature drops.

[0055] like Figure 6 As shown, the control method is as follows:

[0056] S1: The system is powered on, and the temperature sensor of the spectral conversion module confirms that the operating temperature is normal.

[0057] S2: The treatment head contacts the skin and is confirmed by the sensor.

[0058] S3: Auxiliary light source turned on, image sensor acquires skin image;

[0059] S4: The processor runs the hair follicle detection algorithm to process the image and outputs a set of hair follicle coordinates {(x_i, y_i, d_i)}, where d_i is the estimated diameter of the i-th hair follicle;

[0060] S5: Map the hair follicle coordinates to an 8×8 VCSEL pixel grid to generate the illumination vector L[p][q]:

[0061] Pixels without hair follicles: L[p][q] = 0

[0062] For pixels with hair follicles: L[p][q] = f(d_i, skin_type), where f is the energy calculation function, which takes the hair follicle thickness and skin color type as input and outputs the optimal pulse energy. The processor inputs the hair follicle coordinates, diameter d_i, and skin color level skin_type measured by the skin color sensor into the energy calculation function f. This function determines the basic energy density range based on the skin color level, and then performs fine adjustments based on the hair follicle diameter to generate the final pulse energy parameters acting on the pixel.

[0063] S6: The processor simultaneously sets the on / off state and pulse width of 64 MOSFETs through a shift register;

[0064] S7: Trigger pulse emission - All VCSELs with L[p][q]>0 synchronously emit pulse light to pump the spectral conversion module and output incoherent broadband pulse light, which irradiates the skin after passing through the ultraviolet cutoff filter and the thermal window;

[0065] S8: Acquire images after illumination and compare and evaluate the coverage effect;

[0066] S9: Record the data for this treatment, including location, energy, number of hair follicles, and temperature curve, and upload it to the APP for treatment management.

[0067] Energy Calculation: 64 VCSELs, single-pulse peak power 5W, pulse width 10ms, total pump energy E_pump = 3.2J. Fluorescence conversion efficiency η_conv is taken as 50%, and the transmittance of the fluorescent layer to 808nm T_pass is taken as 30%. Therefore, the total output energy E_total = E_pump × 50% + E_pump × 50% × 30% = 1.6J + 0.48J = 2.08J. The effective irradiation area is 1.44cm², and the output energy density F = 2.08 / 1.44 = 14.4 J / cm², which is within the effective threshold range for hair removal (10-20 J / cm²).

[0068] Example 2

[0069] The main difference between this embodiment and Embodiment 1 is that the spectral conversion module adopts a quantum dot composite thin film form.

[0070] like Figure 1 and Figure 3 As shown, the quantum dot composite film has a thickness of 0.1-0.5 mm and is made by dispersing semiconductor quantum dots of different sizes in a polymer matrix, which can be PMMA or silicone, and is laminated onto a transparent substrate. The quantum dot formulation is optimized for 808nm pumping, and the specific components are shown in Table 2.

[0071] Table 2

[0072]

[0073] The quantum dot solution boasts a conversion efficiency of 60-85%, with an optimal 75%, significantly higher than the 40-60% of the phosphor solution, meaning an approximately 50% increase in output energy density at the same laser power. Quantum dots allow for precise design of the emission wavelength by controlling particle size, offering far greater spectral customizability than phosphors. The use of InP-based and CuInS2-based cadmium-free quantum dots avoids the cadmium toxicity issues associated with CdSe quantum dots, complying with RoHS and WEEE environmental directives.

[0074] The other modules and operating methods are the same as in Example 1, and the control method is the same as in Example 1.

[0075] Example 3

[0076] This embodiment adds a six-axis inertial measurement unit (IMU) to the embedded processor, based on embodiment 1 or 2, for real-time detection of the sliding speed V and direction D of the treatment head.

[0077] Due to the extremely fast response speed of the VCSEL array (µs-level switching), this system can support a sliding continuous illumination mode. In this mode:

[0078] like Figure 5 and Figure 6 As shown, the processor continuously updates the illumination vector at a frequency of no less than 30fps to compensate for motion offset. The system automatically adjusts the pulse frequency f and single pulse energy E according to the speed V to ensure that each hair follicle receives exactly one effective irradiation (without repetition or omission). The compensation formula is: Pulse spacing = V / f ≤ pixel spacing (1.5mm). When V is too fast, the system issues a deceleration warning.

[0079] In swipe mode, users do not need to perform the tedious operation of pressing, waiting, lifting, and moving. They can simply swipe naturally like a razor to complete hair removal, reducing the whole-body hair removal time from the traditional 15-30 minutes to 3-5 minutes.

[0080] The other modules and operating methods are the same as in Embodiment 1 or 2. The control method is based on steps S1-S9 of Embodiment 1, with the addition of a sliding continuous irradiation step:

[0081] S8a: The IMU continuously monitors motion status, including velocity V and direction D;

[0082] S8b: The AI ​​model updates the lighting vector at a frequency of ≥30fps to compensate for motion offset;

[0083] S8c: The system automatically triggers a pulse sequence at a frequency of f = V / pixel_pitch;

[0084] S8d: Prompts the user to slow down when the speed exceeds the limit.

[0085] Although embodiments of the present invention have been described in the specification, these embodiments are merely illustrative and should not be construed as limiting the scope of protection of the present invention. Various omissions, substitutions, and modifications made without departing from the spirit of the present invention should be included within the scope of protection of the present invention.

Claims

1. A pulsed light hair removal system based on spectral conversion, characterized in that, include: A pump light source module, wherein the pump light source module is an array composed of multiple independently controllable laser diodes; A spectral conversion module is located in front of the light-emitting front of the pump light source module. It is used to absorb the laser emitted by the laser diode and convert it into incoherent broadband pulsed light through spontaneous emission. The image acquisition module is used to acquire skin images; The processor, connected to the image acquisition module and the pump light source module respectively, is used to generate control signals to independently control the on / off state of the lasers at corresponding positions in the laser diode array based on the hair follicle positions in the skin image, so as to achieve pixel-level precise irradiation.

2. The pulsed light hair removal system based on spectral conversion according to claim 1, characterized in that, The spectral conversion module has an opaque isolation structure inside, which divides the spectral conversion module into multiple independent conversion regions corresponding one-to-one with the laser diode array, in order to suppress fluorescence lateral diffusion and maintain pixel-level spatial accuracy.

3. The pulsed light hair removal system based on spectral conversion according to claim 2, characterized in that, The opaque isolation structure can be one of the following: Method 1: A metal mesh groove running through the entire thickness of the spectral conversion module, the mesh groove being filled with an opaque material; Method 2: A discrete fluorescent material dot array formed on a transparent substrate by printing or photolithography, wherein the spacing of the fluorescent material dot array matches the spacing of the laser diode array; Method 3: An optical fiber bundle consisting of multiple closely arranged optical fibers, with the core of each fiber filled with fluorescent or quantum dot materials.

4. The pulsed light hair removal system based on spectral conversion according to claim 1, characterized in that, It also includes a skin color sensor and a skin temperature sensor. The processor is connected to the skin color sensor and the skin temperature sensor respectively, and is used to automatically limit the maximum output energy density according to the Fitzpatrick skin color level determined by the skin color sensor, and to automatically reduce the energy or stop irradiation when the temperature exceeds a preset threshold according to the reading of the skin temperature sensor.

5. The pulsed light hair removal system based on spectral conversion according to claim 1, characterized in that, The spectral conversion module is a detachable and replaceable modular structure, which is installed in the treatment head by magnetic attraction or snap-fit. Different modules correspond to different fluorescent material formulations and cutoff filter combinations. The module integrates an NFC tag for storing module type and usage count information.

6. The pulsed light hair removal system based on spectral conversion according to claim 1, characterized in that, The spectral conversion module is a fluorescence conversion layer or a quantum dot conversion layer. The fluorescence conversion layer contains at least two phosphors with different emission wavelengths, and the quantum dot conversion layer contains at least two semiconductor quantum dots with different particle sizes, so that the output spectrum covers the 500-1200nm range.

7. The pulsed light hair removal system based on spectral conversion according to claim 6, characterized in that, The semiconductor quantum dots in the quantum dot conversion layer are InP-based or CuInS2-based cadmium-free quantum dots.

8. The pulsed light hair removal system based on spectral conversion according to claim 1, characterized in that, The output light of the spectral conversion module is incoherent light, the spectral half-width of which is greater than 200 nm, and it is emitted in a pulsed manner.

9. The pulsed light hair removal system based on spectral conversion according to claim 1, characterized in that, The control signal is a lighting vector corresponding to the laser diode array. Each element in the lighting vector is independently set to zero or a specific energy parameter. The energy parameter is determined according to the diameter or number of hair follicles in the corresponding pixel area to achieve adaptive energy control.

10. The pulsed light hair removal system based on spectral conversion according to claim 1, characterized in that, The hair removal system also includes an inertial measurement unit for real-time detection of the motion state of the treatment head. The processor updates the control signal and adjusts the pulse emission frequency in real time according to the motion state to support the sliding continuous irradiation mode.

11. The pulsed light hair removal system based on spectral conversion according to claim 1, characterized in that, A microlens array is also provided between the pump light source module and the spectral conversion module. The microlens array corresponds one-to-one with the laser diode and is used to collimate the diverging beam of each laser and project it onto the corresponding area on the spectral conversion module to reduce optical crosstalk.

12. The pulsed light hair removal system based on spectral conversion according to claim 1, characterized in that, An ultraviolet cut-off filter and a heat-conducting window are arranged sequentially behind the spectral conversion module. The ultraviolet cut-off filter is used to filter out ultraviolet light, and the heat-conducting window is used to transmit therapeutic light and conduct heat.

13. A pulsed light hair removal method based on spectral conversion, applied to the pulsed light hair removal system based on spectral conversion as described in any one of claims 1-12, characterized in that, Includes the following steps: Acquire skin images; Identify hair follicle coordinates from the skin image; The hair follicle coordinates are mapped to the pixel grid of the laser diode array to generate control signals for controlling the independent on / off state of each laser. According to the control signal, the corresponding laser is selectively driven to emit pump light pulses; The pump light pulse excitation spectrum conversion module converts the light into incoherent broadband pulse light and outputs it to the skin surface.

14. The pulsed light hair removal method based on spectral conversion according to claim 13, characterized in that, The energy parameter in the control signal is calculated and determined based on at least one of the following factors: the diameter and number of hair follicles in the corresponding pixel area, and the user's skin color type.

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