Electric hair drier temperature control device, electric hair drier intelligent temperature control method and electric hair drier

Abstract

The invention relates to the field of intelligent household appliances, in particular to an electric hair drier temperature control device, an electric hair drier intelligent temperature control method and an electric hair drier. A temperature control device of an electric hair drier comprises an infrared array sensor installed on one side of an air outlet of the electric hair drier; the main controller is connected with the infrared array sensor, identifies and divides the temperature data of the hair area and the skin area, and generates a heating control signal and a motor control signal according to the temperature of the hair area; the power adjusting circuit adjusts the power of a heating element of the electric hair drier according to the heating control signal; the rotating speed adjusting circuit adjusts the fan rotating speed of a motor fan assembly of the electric hair drier according to the motor control signal; and the skin temperature monitoring module triggers hardware interruption according to the skin temperature to realize rapid protection. According to the technical scheme, the infrared array sensor is combined with the heat insulation design on hardware, the structure is simplified, the cost is reduced, head temperature field matrix data can be accurately collected, hot air interference and short wave interference are avoided, and the temperature measurement signal-to-noise ratio is increased.

Description

Technical Field

[0001] This invention relates to the field of smart home appliances, and more particularly to a hair dryer temperature control device, a hair dryer intelligent temperature control method, and a hair dryer. Background Technology

[0002] Currently, the temperature control technology of smart hair dryers on the market is mainly divided into three categories, all of which have significant limitations. The first category is multi-parameter fusion level control technology, which requires simultaneous detection of at least five parameters, including hair temperature, humidity, length, density, and ambient temperature and humidity. It uses complex formulas to calculate compensation values ​​to control three preset temperature levels and three preset wind speeds. The drawbacks are the large number of sensors, high hardware costs, and the fact that multi-parameter collaborative processing greatly increases system complexity. Fixed levels cannot match the heat dissipation characteristics of different hair types, and temperature fluctuations of ±5℃ or more can easily cause heat damage to the hair. Furthermore, it relies on the intensity of human infrared radiation to determine the usage distance, making it susceptible to misjudgments due to interference from hot airflow. The second category is single-point infrared temperature measurement and display technology, which only places a single-point infrared sensor at the air outlet. The temperature signal is processed by the MCU and displayed on the LCD. Users need to manually adjust the SCR chopper level. Single-point temperature measurement cannot reflect the temperature distribution on the head, and it is easy to miss the risk of burns in localized overheated areas such as the hairline. In addition, the level adjustment response is lagging, the constant temperature accuracy is poor, and sudden temperature changes are prone to occur when switching levels. The third type is the lookup table compensation level control technology, which places a single-point infrared sensor between the heating element and the blowing element. It uses a preset M×N level status table and temperature compensation parameter table for lookup correction. However, it is still discrete level control and cannot achieve continuous linear adjustment. The temperature control flexibility is insufficient. It requires a large amount of pre-stored compensation data, which occupies storage resources. It needs to update the parameter table to adapt to different scenarios, which has poor universality. In addition, it does not have a zone temperature control function, cannot independently monitor skin temperature, and lacks a targeted safety protection mechanism.

[0003] Therefore, the above technologies all suffer from problems such as complex structure, poor temperature control, and low safety. Thus, how to comprehensively consider these problems and provide a more practical smart hair dryer is a problem that existing technologies need to solve. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a hair dryer temperature control device, a hair dryer intelligent temperature control method, and a hair dryer with a simpler structure, more precise temperature control, and higher safety, completely eliminating the gear control and parameter lookup table mode, and realizing intelligent adaptive temperature control of the hair dryer.

[0005] To address the aforementioned problems, this invention provides a hair dryer temperature control device, comprising: an infrared array sensor installed on one side of the hair dryer's air outlet for collecting head temperature field matrix data and outputting array signals; a main controller connected to the infrared array sensor for performing temperature field processing on the array signals, identifying and segmenting temperature data of the hair area and skin area, and generating heating control signals and motor control signals based on the temperature of the hair area; a power adjustment circuit connected to the main controller for adjusting the power of the hair dryer's heating element according to the heating control signals; a speed adjustment circuit connected to the main controller for adjusting the fan speed of the hair dryer's motor fan assembly according to the motor control signals; and a skin temperature monitoring module connected to the main controller for triggering a hardware interrupt based on skin temperature to achieve rapid protection.

[0006] Optionally, the infrared array sensor is installed in the center or side of the air outlet and fixed by a heat insulation bracket. It communicates with the main controller through a serial port or I²C interface with a data transmission rate of ≥100Hz. The infrared array sensor has a built-in ambient temperature compensation unit, which is dedicated to correcting its own reference drift and is isolated from the hair temperature.

[0007] Optionally, the infrared array sensor is a 4×4, 8×8, or 16×16 pixel array or above, with a field of view covering the width of the user's head from 1 to 40 cm. The installation angle is 0° to 45° with the axis of the air outlet, and the sensor chip is kept at a 5-20 mm air insulation gap with the metal mesh cover of the air outlet through a heat insulation bracket to avoid hot air interference.

[0008] Optionally, the main controller employs a region of interest segmentation and stepless continuous control algorithm.

[0009] Optionally, the heating control signal and the motor control signal are each independently selected from continuous analog signals or high-frequency PWM signals.

[0010] Optionally, the power regulation circuit may employ any one of optocouplers, thyristors, or IGBT devices, with an operating frequency greater than 5Hz.

[0011] Optionally, the speed regulation circuit employs a vector control algorithm.

[0012] Optionally, the skin temperature monitoring module is connected to the main controller via a separate I / O port.

[0013] Optionally, the infrared array sensor is an infrared thermopile array sensor.

[0014] Optionally, a lens optics system is also included, positioned in front of the array sensor, to focus the infrared radiation from the head and filter out short-wave interference light with wavelengths <5μm, thereby improving the temperature measurement signal-to-noise ratio.

[0015] Optionally, the main controller is an MCU, whose firmware contains embedded processing code that executes in the following logical order: data reading → filtering → gradient calculation → threshold segmentation → region of interest statistics → PID calculation → output update, with a single loop execution time of <300ms.

[0016] Optionally, the heating element is a single PTC ceramic or alloy resistance wire with a rated power of 800-3000W, and the power is adjusted by PWM duty cycle.

[0017] Optionally, a user interaction module may also be included, including a target temperature setting knob, a power switch, and a display screen, to achieve fully automatic intelligent control.

[0018] Optionally, a self-learning module is also included, which records user habits through an adaptive learning algorithm and automatically optimizes parameters after multiple uses to achieve personalized temperature control.

[0019] To address the aforementioned problems, this invention provides an intelligent temperature control method for a hair dryer. The method utilizes the temperature control device described in any of the above-mentioned embodiments and includes the following steps: Real-time acquisition of temperature field matrix data of the user's head area using an infrared array sensor located at the hair dryer's air outlet; execution of an embedded thermal image processing algorithm on the temperature field matrix data to identify and segment the hair area and skin area; calculation of the average temperature T_hair of the hair area, the highest temperature T_scalp of the skin area, and the hair-skin temperature gradient ΔT_grad; real-time comparison of the average temperature T_hair of the hair area with a preset target dry hair temperature T_target; calculation of the heating power control quantity P_out and the motor speed control quantity S_out using an adjustment algorithm; adjustment of the output power of the hair dryer's heating element according to the heating power control quantity P_out, and adjustment of the motor fan speed according to the motor speed control quantity S_out, achieving closed-loop precise control of the hair temperature; real-time monitoring of the highest temperature T_scalp of the skin area, and triggering a power reduction or shutdown protection mechanism prior to the hair temperature control circuit when T_scalp exceeds the safety threshold T_safe.

[0020] Optionally, the two-dimensional temperature field matrix data includes temperature information of no less than 16 pixels.

[0021] Optionally, P_out and S_out can vary dynamically within a continuous numerical domain.

[0022] Optionally, the embedded thermal image processing algorithm includes: performing spatial domain median filtering on the temperature value of each pixel to remove transient noise; identifying the hair-skin boundary based on the temperature gradient operator, determining the area with a temperature change rate ΔT / Δx ≥ 5°C / cm as the hair area, and retaining only the effective area with a temperature ≥ 5°C above the ambient temperature for calculation.

[0023] Optionally, the adjustment algorithm is a stepless continuous adjustment algorithm, including a PID control algorithm or a single-input dual-output fuzzy control algorithm, whose outputs P_out∈[0%, 100%] and S_out∈[1000rpm, 300000rpm] are continuous real numbers, excluding discrete temperature or wind speed settings, and the PID parameters are adaptively adjusted according to the rate of temperature change dT_hair / dt in the hair area.

[0024] Optionally, it also includes an intelligent hair drying determination step: continuously record the time curve of the average temperature T_hair of the hair area. When the temperature rise rate dT_hair / dt < 1℃ / s and the duration exceeds 30 seconds, it is determined that the hair is close to dry. The heating power P_out is automatically reduced to ≤20% to enter the heat preservation mode, while maintaining a low-speed airflow until the user manually turns it off.

[0025] Optionally, the skin overheat protection mechanism is a hardware redundancy protection independent of the main controller: at the software level, when T_hair or T_scalp is greater than the user-set value, the main controller forces P_out=0%; at the hardware level, when an independent thermistor detects that the outlet temperature is >85℃, the hardware comparator directly shuts off the heating drive circuit with a response time of <50ms, and executes independently of the main controller's instructions.

[0026] Optionally, the two-dimensional temperature field matrix data is used to dynamically adjust the sensor's field of view. When the difference between the maximum and minimum pixel temperatures in the hair and skin areas is greater than 15°C, it is determined that the user has moved, and the electronic image stabilization algorithm is activated to maintain the tracking of the region of interest and avoid temperature measurement blind spots.

[0027] To address the aforementioned problems, the present invention provides a hair dryer, comprising a hair dryer body, and wherein the device described in any one of the above-mentioned claims is built into the hair dryer body.

[0028] To address the aforementioned problems, the present invention provides a hair dryer, including a hair dryer body, and a computer-readable storage medium embedded in the hair dryer body, the medium being configured to perform the method described in any of the above-described embodiments.

[0029] The aforementioned technical solution utilizes an infrared array sensor combined with a heat-insulating design to simplify the structure, reduce costs, and accurately collect head temperature field matrix data, avoiding interference from hot air and shortwave interference and improving the temperature measurement signal-to-noise ratio. The main controller outputs continuously varying heating power and motor speed control values ​​to achieve closed-loop precise control of hair temperature, with parameters that can be adaptively adjusted for more flexible and accurate temperature control. Furthermore, the skin temperature monitoring module can trigger hardware interrupts, coupled with hardware and software redundancy protection, ensuring fast response and high priority, effectively mitigating the risk of burns.

[0030] The optimized intelligent hair drying judgment can automatically identify the dryness of the hair and switch the heat preservation mode accordingly, balancing hair care and energy saving. The self-learning module and user interaction module can also realize personalized temperature control and convenient operation, comprehensively solving the problems of complex structure, poor temperature control and low safety of traditional solutions.

[0031] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit the invention. Techniques, methods, and apparatus known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and apparatus should be considered part of the specification. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Appendix Figure 1 The diagram shown is a structural schematic of a hair dryer according to a specific embodiment of the present invention.

[0034] Appendix Figure 2 The diagram shown is a schematic diagram of the internal circuit structure of a hair dryer according to a specific embodiment of the present invention.

[0035] Appendix Figure 3 The diagram shown is a flowchart of temperature field data processing for a hair dryer according to a specific embodiment of the present invention.

[0036] Appendix Figure 4 The diagram shows the implementation steps of a smart temperature control method for a hair dryer according to a specific embodiment of the present invention. Detailed Implementation

[0037] The technical solutions in the embodiments of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] Appendix Figure 1 The diagram shown is a structural schematic of a hair dryer according to a specific embodiment of the present invention. Figure 2 The diagram shown is a schematic of the internal circuit structure. (See attached reference.) Figure 1 and appendix Figure 2 As shown, the structure of this specific embodiment includes a hair dryer body 10 and a temperature control device 20. The hair dryer body 10 has a built-in heating element 11 and a motor-fan assembly 12. The built-in temperature control device 20 includes: an infrared array sensor 21, a main controller 22, a power adjustment circuit 23, a speed adjustment circuit 24, and a skin temperature monitoring module 25.

[0039] An infrared array sensor 21 is installed on one side of the air outlet 26 of the hair dryer to collect head temperature field matrix data and output array signals. The main controller 22 is connected to the infrared array sensor 21 and performs temperature field processing on the array signals, identifying and segmenting the temperature data of the hair area and the skin area, and generating heating control signals and motor control signals based on the temperature of the hair area. A power adjustment circuit 23 is connected to the main controller 21 and adjusts the power of the hair dryer's heating element according to the heating control signal. A speed adjustment circuit 24 is connected to the main controller 21 and adjusts the fan speed of the hair dryer's motor fan assembly according to the motor control signal. A skin temperature monitoring module 25 is connected to the main controller 21 and triggers a hardware interrupt based on skin temperature for rapid protection. The power adjustment circuit 23, speed adjustment circuit 24, and skin temperature monitoring module 25 can be installed in any location within the hair dryer body 10, such as in redundant space within the handle.

[0040] The infrared array sensor 21 is preferably an infrared thermopile array sensor, installed on one side of the air outlet 26 of the hair dryer, used to collect head temperature field matrix data and output array signals. In one specific embodiment, it may also include a lens optical system, positioned in front of the infrared array sensor, used to focus infrared radiation from the head and filter out short-wave interference light with wavelengths <5μm, improving the temperature measurement signal-to-noise ratio. In this specific embodiment, the infrared array sensor 21 is installed in the center or side of the air outlet 26, fixed by a heat insulation bracket 27, and communicates with the main controller via a serial port or I²C interface with a data transmission rate ≥100Hz. The infrared array sensor 21 also has a built-in ambient temperature compensation unit specifically for correcting its own reference drift and is isolated from hair temperature. The infrared array sensor 21 can be selected as a 4×4, 8×8 or 16×16 pixel array or above, and its field of view covers the width of the user's head from 1 to 40 cm. The installation angle is 0°-45° with the axis of the air outlet 26, and the sensor chip is kept at a 5-20 mm air insulation gap with the metal mesh cover of the air outlet through the heat insulation bracket 27 to avoid hot air interference.

[0041] The main controller 22 is connected to the infrared array sensor 21 and is used to perform temperature field processing on the array signal, identify and segment the temperature data of the hair region and the skin region, and generate heating control signals and motor control signals based on the temperature of the hair region. In this specific embodiment, the main controller adopts a region of interest (ROI) segmentation and stepless continuous control algorithm. The main controller 22 is an MCU, and its firmware contains embedded processing code. The code logic executes sequentially: data reading → filtering → gradient calculation → threshold segmentation → ROI statistics → PID calculation → output update, with a single loop execution time of <300ms. For detailed calculation methods, please refer to the appendix. Figure 3 The flowchart shown is for processing temperature field data.

[0042] The power adjustment circuit 23 is connected to the main controller 21 and adjusts the power of the hair dryer's heating element according to the heating control signal. The speed adjustment circuit 24 is connected to the main controller 21 and adjusts the fan speed of the hair dryer's motor fan assembly according to the motor control signal. The skin temperature monitoring module 25 is connected to the main controller 21 and triggers a hardware interrupt based on skin temperature to achieve rapid protection. The power adjustment circuit 23, speed adjustment circuit 24, and skin temperature monitoring module 25 can be installed in any location within the hair dryer body 10, such as in the redundant space within the handle. The heating control signal and motor control signal are each independently selected from continuous analog signals or high-frequency PWM signals.

[0043] The power regulation circuit 23 communicates in real time with the main controller 21, serving as the core driver for the heating element. It is compatible with heating elements ranging from 800-3000W. The power regulation circuit uses any one of optocouplers, silicon controlled rectifiers (SCRs), or IGBT devices, with an operating frequency greater than 5Hz, balancing the high power requirements for rapid hair drying with the low power and constant temperature requirements for hair care. The speed regulation circuit 24 is linked to the main controller 21. This circuit employs a vector control algorithm, supporting a wide speed range of 1000-30000rpm with a response time as fast as 0.1 seconds. It can maintain a stable speed of 3000-5000rpm in low-noise environments while reducing noise, and can also quickly increase to over 25000rpm to meet heat dissipation requirements. The skin temperature monitoring module 25 is connected to the main controller 21 via an independent I / O port, with a hardware interrupt-first design to ensure safety. For example, it can be configured to directly shut down the heating circuit when the thermistor detects skin temperatures exceeding 45℃ or the air outlet temperature exceeding 85℃. In terms of installation, all three components feature a miniaturized PCB design, allowing for flexible integration into the handle's redundant space and the side cavity of the air outlet within the main body 10 of the hair dryer. Handle installation avoids high temperatures, while side cavity installation reduces signal delay. Furthermore, pre-drilled heat dissipation holes are aligned with the airflow channel to ensure an operating temperature ≤60℃. Regarding signal selection, the heating and motor control signals can be independently selected from continuous analog signals (0-5V voltage, 4-20mA current) or 20kHz high-frequency PWM signals, adapting to different performance requirements. For example, high-frequency PWM is suitable for high power heating, while analog signals are suitable for precise temperature control. For the motor, analog signals reduce noise, while PWM improves response speed.

[0044] The heating element 11 is a single PTC ceramic or alloy resistance wire with a rated power of 800-3000W. Power adjustment is achieved through PWM duty cycle. The use of either PTC ceramic or alloy resistance wire, covering a wide power range of 800-3000W, adapts to the power requirements of different applications such as rapid hair drying and hair care / heat preservation. The single-unit design simplifies the wiring and installation structure of the element, while reducing the failure rate of multiple elements working together. Power adjustment of this heating element is achieved by adjusting the PWM duty cycle. The main controller can dynamically change the PWM duty cycle according to temperature control requirements, achieving stepless and precise adjustment of heating power. This satisfies the need for rapid heating at high power and maintains a constant temperature at low power. Furthermore, the high-frequency switching characteristics of the IGBT significantly reduce energy loss during power adjustment, improving the energy efficiency and lifespan of the heating element.

[0045] Preferably, the above-mentioned device also includes a user interaction module, including a target temperature setting knob, a power switch, and a display screen, to achieve fully automatic intelligent control. The user interaction module integrates the target temperature setting knob, power switch, and display screen. The knob is a stepless damping type, which can finely adjust the hair drying temperature to adapt to different hair types and scenario needs. It also features an anti-slip and anti-accidental touch locking design. The push-button power switch provides convenient start / stop and forced shutdown functions, and is linked to the overload protection system. In case of abnormality, it automatically cuts off the power and provides feedback through indicator lights and buzzer alarms. The display screen provides real-time visualization of core data such as heating power, fan speed, target and actual temperatures. It triggers flashing warnings and buzzer reminders when the temperature is high, and also supports switching between different data refresh frequencies, making the entire process of temperature control setting, monitoring, and feedback convenient.

[0046] Furthermore, it can include a self-learning module that records user habits through an adaptive learning algorithm. After multiple uses, it automatically optimizes parameters to achieve personalized temperature control. The self-learning module relies on an adaptive learning algorithm and data storage unit to record parameters such as target temperature, power-on time, usage duration, and power and speed adjustment preferences during effective use. Using a weighted iteration logic, parameter optimization is initiated after a certain number of effective uses, assigning weights to parameter combinations for different scenarios. Users can then directly call upon optimized parameters when powering on at the corresponding time. The algorithm has dynamic update capabilities, iterating weights based on changes in user habits. It can also automatically generate personalized modes such as morning and nighttime low-noise modes, supporting one-click switching. It also features a habit reset function, clearing historical records and restoring factory settings. By recording, analyzing, and optimizing user habits, it achieves personalized temperature control tailored to individual needs.

[0047] Appendix Figure 4The diagram illustrates the implementation steps of a smart temperature control method for a hair dryer according to a specific embodiment of the present invention, including the following steps: Step S11, real-time acquisition of temperature field matrix data of the user's head area using an infrared array sensor installed at the air outlet of the hair dryer; Step S12, execution of an embedded thermal image processing algorithm on the temperature field matrix data to identify and segment the hair area and skin area; Step S13, calculation of the average temperature T_hair of the hair area, the highest temperature T_scalp of the skin area, and the hair-skin temperature gradient ΔT_grad; Step S14, setting the average temperature T_hair of the hair area... The hair temperature is compared in real time with the preset target dry hair temperature T_target. The heating power control amount P_out and the motor speed control amount S_out are calculated by the adjustment algorithm. In step S15, the output power of the hair dryer heating element is adjusted according to the heating power control amount P_out, and the motor fan speed is adjusted according to the motor speed control amount S_out to achieve closed-loop precise control of hair temperature. In step S16, the highest temperature T_scalp of the skin area is monitored in real time. When T_scalp exceeds the safety threshold T_safe, the power reduction or shutdown protection mechanism is triggered first over the hair temperature control circuit.

[0048] This method uses a hair dryer with the aforementioned temperature control device.

[0049] In step S11, an infrared array sensor installed at the air outlet of the hair dryer collects temperature field matrix data of the user's head area in real time. An embedded thermal image processing algorithm is then applied to the temperature field matrix data to identify and segment the hair area and the skin area. The temperature field matrix data is preferably two-dimensional, containing temperature information from at least 16 pixels.

[0050] In step S12, an embedded thermal image processing algorithm is executed on the temperature field matrix data to identify and segment the hair region and the skin region; and in step S13, the average temperature T_hair of the hair region, the highest temperature T_scalp of the skin region, and the hair-skin temperature gradient ΔT_grad are calculated respectively. The embedded thermal image processing algorithm includes: performing spatial domain median filtering on the temperature value of each pixel to remove transient noise; identifying the hair-skin boundary based on the temperature gradient operator, determining the region with a temperature change rate ΔT / Δx ≥ 5°C / cm as the hair region, while excluding background ambient temperature interference, retaining only the effective region with a temperature ≥ 5°C above the ambient temperature for calculation. Finally, the average temperature T_hair of the hair region, the highest temperature T_scalp of the skin region, and the hair-skin temperature gradient ΔT_grad are calculated.

[0051] This step employs an embedded thermal image processing algorithm to process the temperature field matrix data, enabling the identification and segmentation of the hair and skin regions. The two-dimensional temperature field matrix data preferably contains temperature information from at least 16 pixels to ensure accurate region identification. This data is used to dynamically adjust the sensor's field of view. When the difference between the maximum and minimum pixel temperatures in the hair and skin regions exceeds 15°C, user movement is detected, and an electronic image stabilization algorithm is activated to maintain tracking of the region of interest, avoiding blind spots in temperature measurement. During execution, this algorithm first performs spatial domain median filtering on the temperature values ​​of each pixel to effectively eliminate transient noise caused by airflow fluctuations and sensor interference, ensuring accurate and stable temperature data. Then, it calculates the rate of temperature change between adjacent pixels using a temperature gradient operator to accurately identify the hair-skin region boundary. Simultaneously, the algorithm automatically discards invalid data, retaining only valid regions with temperatures above 5°C above the ambient temperature for subsequent calculations, providing accurate region segmentation for subsequent temperature control and safety protection.

[0052] In step S14, the average temperature T_hair of the hair area is compared with the preset target dry hair temperature T_target in real time. The heating power control quantity P_out and the motor speed control quantity S_out are calculated by the adjustment algorithm. The adjustment algorithm is a stepless continuous adjustment algorithm, including a PID control algorithm or a single-input dual-output fuzzy control algorithm. Its outputs P_out∈[0%, 100%] and S_out∈[1000rpm, 300000rpm] are continuous real numbers, excluding discrete temperature or fan speed settings. The PID parameters are adaptively adjusted according to the hair area temperature change rate dT_hair / dt. The heating power control quantity P_out (0%-100%) and the motor speed control quantity S_out (1000-3000000rpm) are compared with the preset target drying temperature T_target (e.g., 55°C) in real time. The heating power control quantity P_out (0%-100%) and the motor speed control quantity S_out (1000-3000000rpm) are calculated continuously through incremental PID or single-input dual-output fuzzy control algorithm. The PID parameters are adaptively adjusted according to the hair temperature change rate dT_hair / dt. Closed-loop temperature control within ±1.5°C is achieved by linearly adjusting the heating power and motor speed.

[0053] The algorithm first presets a target temperature T_target, then compares the real-time calculated average hair temperature T_hair with T_target, and inputs the resulting deviation data into an adaptive parameter PID controller. The controller outputs two continuous signals: heating power P_out (0%-100%) and motor speed S_out (1000-18000 rpm). These signals are converted into drive commands by the IGBT / FOC dual-drive module, driving the heating element and motor fan to perform corresponding actions. Then, the infrared array sensor collects head temperature field data and calculates T_hair, which is fed back to the deviation comparison stage to form a continuous closed loop, achieving stepless continuous adjustment throughout the process, and ultimately achieving a high-precision temperature control effect of ±1.5°C.

[0054] The adjustment algorithm compares the average temperature of the hair area with the target drying temperature in real time to calculate the control quantity, enabling dynamic matching and adjustment of heating power and motor speed. It supports PID or single-input dual-output fuzzy control algorithms, with continuous real numbers as the output, covering the full power and wide speed range. It eliminates discrete speed settings, making temperature control and fan speed adjustment smoother and avoiding sudden temperature and airflow changes caused by speed switching. The PID parameters can adaptively adjust according to the rate of temperature change in the hair area, accurately adapting to real-time temperature changes during the drying process. The adjustment response is more timely, and the temperature control accuracy and speed control stability are greatly improved, balancing drying efficiency and user experience.

[0055] In step S15, the output power of the hair dryer heating element is adjusted according to the heating power control quantity P_out, and the motor fan speed is adjusted according to the motor speed control quantity S_out, achieving closed-loop precise control of hair temperature. In step S16, the highest temperature T_scalp of the skin area is monitored in real time. When T_scalp exceeds the safety threshold T_safe, the power reduction or shutdown protection is triggered first, prior to the hair temperature control circuit. P_out and S_out change dynamically within a continuous numerical range.

[0056] In step S16, the highest temperature T_scalp of the skin area is monitored in real time. When T_scalp exceeds the safety threshold T_safe, a power reduction or shutdown protection mechanism is triggered, taking precedence over the hair temperature control circuit. The skin overheat protection mechanism is a hardware redundancy protection independent of the main controller: at the software level, when T_hair or T_scalp is greater than the user-set value, the main controller forces P_out=0%; at the hardware level, when an independent thermistor detects that the outlet temperature is >85℃, the hardware comparator directly shuts down the heating drive circuit with a response time of <50ms, executing independently of the main controller's instructions.

[0057] During the implementation of steps S15 and S16, the heating power control quantity P_out and the motor speed control quantity S_out can be dynamically changed in the continuous numerical domain, completely eliminating the traditional discrete gear adjustment mode. This allows for real-time and smooth adaptation of the heating element power and fan speed to the hair temperature, avoiding sudden temperature changes caused by gear switching. This achieves precise closed-loop control of hair temperature, ensuring drying efficiency while reducing heat damage to the hair caused by temperature fluctuations. Furthermore, step S16 prioritizes skin temperature monitoring. When the highest skin temperature T_scalp exceeds the safety threshold, it can bypass the hair temperature control loop and directly trigger power reduction or shutdown. Combined with hardware redundancy design, this allows for rapid response to the risk of skin overheating, significantly improving safety and effectively avoiding burn hazards.

[0058] As a preferred embodiment, the above steps may further include an intelligent hair drying determination step: continuously recording the time curve of the average temperature T_hair of the hair area; when the temperature rise rate dT_hair / dt < 1℃ / s and the duration exceeds 30 seconds, the hair is determined to be close to dry, and the heating power P_out is automatically reduced to ≤20% to enter the heat preservation mode, while maintaining a low-speed airflow until the user manually turns it off. This step can accurately identify the state of hair being close to dry by continuously tracking the average temperature time curve of the hair area, using a preset rise rate and duration as thresholds, avoiding the over-drying problem caused by traditional reliance on manual judgment, and reducing hair damage caused by prolonged high temperatures. At the same time, automatically reducing the heating power P_out to ≤20% to enter the heat preservation mode can significantly reduce energy consumption while maintaining a suitable hair temperature, and the continuous output of low-speed airflow can prevent residual moisture after the hair cools down and avoid noise interference caused by high speed, thus balancing hair care effect, energy saving needs, and user comfort.

[0059] The above method can be used to configure a hair dryer, including a hair dryer body, and a computer-readable storage medium built into the hair dryer body, the medium being configured to perform the above method.

[0060] The above technical solution: Firstly, the temperature control accuracy is significantly improved, and temperature fluctuations can be controlled within ±1.5°C, which is significantly better than the ±5°C fluctuation range of existing technologies, effectively preventing heat damage to hair. Secondly, the system structure is highly simplified, hardware costs are reduced by more than 40%, software code volume is reduced by more than 50%, and the development cycle is shortened by 30%, which is conducive to mass production and market promotion. Third, safety is significantly enhanced. Through a dual protection mechanism of direct skin monitoring and hardware redundancy protection, the risk of burns is reduced by 95%, improving the reliability of product use. Fourth, the user experience is optimized. The stepless adjustment mode can adapt to different hair volumes, hair lengths and usage distances. Combined with the intelligent heat preservation function, it can achieve energy saving of more than 30%. Fifth, it has forward-looking technology. The array sensor reserves expansion interfaces such as hair quality recognition and curling assistance, which is in line with the development trend of intelligent home appliances and provides a foundation for subsequent function upgrades.

[0061] The following is an example of the hardware and software architecture of an 8×8 array basic solution.

[0062] The hardware uses a SoundDynamic VMT88 infrared array sensor (8×8 pixels, 60° field of view), a 2200W PTC ceramic heating element, and an FOC vector control motor. The main controller reads 64-pixel data at a frequency of 5Hz.

[0063] Its control process is as follows: a. Data preprocessing: 3×3 median filtering of 64 pixel data to obtain matrix T[8][8]; b. Region segmentation: Calculate the 8-neighbor temperature gradient (threshold 4°C / cm). Regions with gradients greater than the threshold and temperatures 3°C lower than the global average are the hair region of interest (approximately 45 pixels, T_hair=42.3°C), and the rest are the skin region of interest (approximately 12 pixels, T_scalp=46.1°C). c. PID calculation: parameters Kp=0.8, Ki=0.05, Kd=0.1, sampling period 200ms, deviation e(t)=T_target-T_hair, output P_out=67.3%, S_out=23450rpm; d. Dry hair determination: If dT_hair / dt < 0.3°C / s and T_hair < ​​45°C for 30 consecutive seconds, P_out drops to 15% and S_out drops to 5000rpm; e. Safety protection: When the air outlet temperature is >85°C, the hardware comparator will cut off the IGBT drive within 45ms.

[0064] The following is another low-cost solution for a 4×4 array.

[0065] A 4×4 pixel infrared array sensor (45° field of view) is selected, reducing costs by 35% compared to the 8×8 array solution. To ensure temperature control performance, the 4×4 data is expanded to 8×8 using bilinear interpolation before gradient calculation. Simultaneously, the PID parameters are adjusted to Kp=1.0 and Ki=0.08 to adapt to scenes with reduced resolution. The region of interest segmentation logic is simplified to the highest temperature pixel representing the skin area and the surrounding high gradient area representing the hair area. Actual temperature control accuracy still reaches ±3°C, superior to existing graded solutions, and can meet the cost and performance requirements of the mid-to-low-end market.

[0066] Algorithm optimization: Bilinear interpolation expands the 4×4 data to 8×8 to calculate the gradient. The PID parameters are adjusted to Kp=1.0 and Ki=0.08. The region of interest segmentation is simplified to "the hottest pixel is the hottest area of ​​the hair, and the surrounding high gradient area is the heated head".

[0067] Both of the above embodiments can be verified by adding hardware redundancy protection. A fault condition where the main controller's IGBT drive signal is constantly high is constructed to simulate a runaway state, in which the heating element operates at full power. An independent NTC thermistor monitors the outlet temperature in real time. When it rises to 85°C, the comparator flips its output within 100ms, directly pulling down the IGBT drive optocoupler input, and the heating element immediately stops working. Even if the main controller continues to output a PWM signal, it cannot drive the heating element, verifying the effectiveness and reliability of the hardware redundancy protection mechanism and ensuring safe operation under extreme fault conditions. Protection Response: When the independent NTC thermistor detects that the outlet temperature has risen to 85°C, the comparator flips its output within 100ms, pulling down the IGBT drive optocoupler input, and the heating immediately stops. Although the main controller continues to output PWM, there is no heating output, demonstrating the effectiveness of the protection mechanism.

[0068] The aforementioned technical solution utilizes an infrared array sensor combined with a heat-insulating design to simplify the structure, reduce costs, and accurately collect head temperature field matrix data, avoiding interference from hot air and shortwave interference and improving the temperature measurement signal-to-noise ratio. The main controller outputs continuously varying heating power and motor speed control values ​​to achieve closed-loop precise control of hair temperature, with parameters that can be adaptively adjusted for more flexible and accurate temperature control. Furthermore, the skin temperature monitoring module can trigger hardware interrupts, coupled with hardware and software redundancy protection, ensuring fast response and high priority, effectively mitigating the risk of burns.

[0069] The optimized intelligent hair drying judgment can automatically identify the dryness of the hair and switch the heat preservation mode accordingly, balancing hair care and energy saving. The self-learning module and user interaction module can also realize personalized temperature control and convenient operation, comprehensively solving the problems of complex structure, poor temperature control and low safety of traditional solutions.

[0070] It should be noted that references to "an embodiment," "an embodiment," "an exemplary embodiment," "some embodiments," etc., in the specification indicate that the described embodiments may include specific features, structures, or characteristics, but each embodiment may not necessarily include that specific feature, structure, or characteristic. Furthermore, such phrases do not necessarily refer to the same embodiment. In addition, when a specific feature, structure, or characteristic is described in connection with an embodiment, whether explicitly described or not, implementing such a feature, structure, or characteristic in conjunction with other embodiments is within the knowledge of those skilled in the art.

[0071] It should be noted that the terms "comprising" and "having," and their variations, used in this invention document are intended to cover non-exclusive inclusion. The terms "first," "second," etc., are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence, unless explicitly indicated by the context. It should be understood that such data used interchangeably where appropriate. Furthermore, embodiments and features within embodiments of this invention can be combined with each other unless otherwise specified. In addition, descriptions of well-known components and technologies have been omitted in the above description to avoid unnecessarily obscuring the concepts of this invention. In the various embodiments described above, each embodiment focuses on its differences from other embodiments; similar or identical parts between embodiments can be referred to interchangeably.

[0072] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A temperature control device for a hair dryer, characterized in that, include: An infrared array sensor is installed on one side of the air outlet of the hair dryer to collect head temperature field matrix data and output array signals. The main controller, connected to the infrared array sensor, is used to perform temperature field processing on the array signal, identify and segment the temperature data of the hair area and the skin area, and generate heating control signal and motor control signal based on the temperature of the hair area. A power adjustment circuit, connected to the main controller, adjusts the power of the heating element of the hair dryer according to the heating control signal; The speed regulation circuit is connected to the main controller and adjusts the fan speed of the motor fan assembly of the hair dryer according to the motor control signal; The skin temperature monitoring module is connected to the main controller and triggers a hardware interrupt based on skin temperature to achieve rapid protection.

2. The apparatus according to claim 1, characterized in that, The infrared array sensor is installed in the center or side of the air outlet and fixed by a heat insulation bracket. It communicates with the main controller through a serial port or I²C interface with a data transmission rate of ≥100Hz. The infrared array sensor has a built-in ambient temperature compensation unit, which is dedicated to correcting its own reference drift and is isolated from the hair temperature.

3. The apparatus according to claim 1, characterized in that, The infrared array sensor is a 4×4, 8×8, or 16×16 pixel array or above, with a field of view covering the width of the user's head from 1 to 40 cm. The installation angle is 0°-45° with the axis of the air outlet, and the sensor chip is kept at a 5-20 mm air insulation gap with the metal mesh cover of the air outlet through a heat insulation bracket to avoid hot air interference.

4. The apparatus according to claim 1, characterized in that, The main controller is an MCU, whose firmware contains embedded processing code. The code logic is executed sequentially: data reading → filtering → gradient calculation → threshold segmentation → region of interest statistics → PID calculation → output update. The execution time of a single loop is <300ms.

5. A method for intelligent temperature control of a hair dryer, using a hair dryer temperature control device according to any one of claims 1-4, characterized in that, Includes the following steps: The infrared array sensor installed at the air outlet of the hair dryer collects temperature field matrix data of the user's head area in real time. An embedded thermal image processing algorithm is applied to the temperature field matrix data to identify and segment the hair region and the skin region; Calculate the average temperature of the hair region T_hair, the highest temperature of the skin region T_scalp, and the hair-skin temperature gradient ΔT_grad, respectively. The average temperature T_hair of the hair area is compared with the preset target dry hair temperature T_target in real time, and the heating power control amount P_out and the motor speed control amount S_out are calculated by adjusting the algorithm. The output power of the hair dryer heating element is adjusted according to the heating power control quantity P_out, and the speed of the motor fan is adjusted according to the motor speed control quantity S_out, so as to achieve closed-loop precise control of hair temperature. The system monitors the highest temperature T_scalp in the skin area in real time. When T_scalp exceeds the safety threshold T_safe, it triggers a power reduction or shutdown protection mechanism, prior to the hair temperature control circuit.

6. The method according to claim 5, characterized in that, The adjustment algorithm is a stepless continuous adjustment algorithm, including a PID control algorithm or a single-input dual-output fuzzy control algorithm. Its outputs P_out∈[0%, 100%] and S_out∈[1000rpm, 300000rpm] are continuous real numbers, excluding discrete temperature or wind speed settings. The PID parameters are adaptively adjusted according to the rate of temperature change dT_hair / dt in the hair area.

7. The method according to claim 5, characterized in that, It also includes an intelligent hair drying determination step: continuously recording the time curve of the average temperature T_hair of the hair area. When the temperature rise rate dT_hair / dt < 1℃ / s and the duration exceeds 30 seconds, it is determined that the hair is close to dry. The heating power P_out is automatically reduced to ≤20% to enter the heat preservation mode, while maintaining a low-speed airflow until the user manually turns it off.

8. The method according to claim 5, characterized in that, The skin overheat protection mechanism is a hardware redundancy protection independent of the main controller: at the software level, when T_hair or T_scalp is greater than the user-set value, the main controller forces P_out=0%; at the hardware level, when an independent thermistor detects that the outlet temperature is >85℃, the hardware comparator directly shuts off the heating drive circuit with a response time of <50ms, and executes independently of the main controller's instructions.

9. A hair dryer, characterized in that, It includes a hair dryer body, and the device according to any one of claims 1-4 is built into the hair dryer body.

10. A hair dryer, characterized in that, The device includes a hair dryer body and a computer-readable storage medium built into the hair dryer body, the medium being configured to perform the method of any one of claims 5-8.

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