A heating control method for a printer fixing unit

Abstract

The application relates to the technical field of printer fixing unit temperature control, in particular to a heating control method of a printer fixing unit, which comprises the following steps: for each heating control period, obtaining a current temperature value and a target temperature value of the fixing unit, and determining a heating duty cycle by using a PID control algorithm based on a temperature difference value between the current temperature value and the target temperature value, wherein proportional, integral and differential coefficients of the PID control algorithm are updated based on the temperature difference value of the corresponding heating control period; determining a corresponding Duty order based on the heating duty cycle; determining a total number of half-wave periods that need to be heated in the current heating control period based on the Duty order; and performing heating control on the fixing unit based on the total number of half-wave periods that need to be heated. The application can perform fine-grained heating control on the fixing unit, so that rapid response and stable control of temperature can be realized in each heating period.

Description

Technical Field

[0001] This application relates to the field of temperature control technology for printer fuser units, and in particular to a heating control method for printer fuser units. Background Technology

[0002] In modern printing equipment, temperature control of the fusing unit has a significant impact on print quality and equipment reliability. Current technologies primarily rely on two methods for fusing unit temperature control: constant temperature control and pulse width modulation (PWM) control.

[0003] Thermostatic control uses a temperature sensor to collect the temperature of the fusing unit in real time and maintains a constant temperature by adjusting the power of the heating element. This method can maintain the temperature within a predetermined range under different printing speeds and environmental conditions, thus ensuring print quality. However, thermostatic control has a slow response time when rapid temperature adjustment is required, and may consume additional energy when the printer is idle or under low load, reducing energy efficiency.

[0004] PWM control achieves precise control of heating power by adjusting the pulse width of the heating element, thereby regulating the temperature of the fixing unit. This method responds quickly in scenarios with rapidly changing temperatures and helps improve energy efficiency. However, relying solely on PWM control is prone to temperature overshoot, leading to large temperature fluctuations and insufficient temperature control stability. Furthermore, high-frequency pulse control may cause electrical problems such as electromagnetic interference and DC bias, affecting equipment safety and reliability.

[0005] Therefore, existing technologies present a clear contradiction between rapid response, temperature control stability, and energy efficiency. Slow temperature control response and high energy consumption, coupled with the tendency of PWM control to overshoot and cause electrical interference, all fail to simultaneously meet the requirements for high precision, high stability, and rapid response in temperature control. Summary of the Invention

[0006] (a) Technical problems to be solved

[0007] In view of the above-mentioned shortcomings and deficiencies of the prior art, this application provides the field of temperature control technology for printer fuser units, which solves the technical problems of slow constant temperature control response, high energy consumption, and PWM control being prone to overshoot and causing electrical interference in the prior art, all of which cannot simultaneously meet the temperature control requirements of high precision, high stability and fast response.

[0008] (II) Technical Solution

[0009] To achieve the above objectives, the main technical solutions adopted in this application include:

[0010] This application provides a heating control method for a printer fuser unit, including:

[0011] For each heating control cycle, the current temperature and target temperature of the fixing unit are obtained. Based on the temperature difference between the current and target temperatures, a PID control algorithm is used to determine the heating duty cycle. The proportional, integral, and derivative coefficients of the PID control algorithm are updated based on the temperature difference of the corresponding heating control cycle. The corresponding duty cycle is determined based on the heating duty cycle. The total number of half-wave cycles that need to be heated in the current heating control cycle is determined based on the duty cycle. The heating control of the fixing unit is then performed based on the total number of half-wave cycles that need to be heated.

[0012] Preferably, in some embodiments of this application, determining the corresponding duty order based on the heating duty cycle includes: determining a pre-divided duty cycle interval to which the heating duty cycle belongs based on the heating duty cycle; determining the corresponding duty class according to the pre-divided duty cycle interval to which the heating duty cycle belongs, and using the duty class as the duty order corresponding to the heating duty cycle.

[0013] Preferably, in some embodiments of this application, the heating control cycle is the time length of N half-wave cycles with an AC voltage of 220V, where N is greater than or equal to 2.

[0014] Preferably, in some embodiments of this application, the duty cycle interval (0%, 100%) is pre-divided into N duty cycle intervals, and the length of each duty cycle interval is 100% / N; each duty cycle interval corresponds to a unique first duty level, and 0% corresponds to a second duty level; each duty level corresponds to a specific number of heating half-wave cycles.

[0015] Preferably, in some embodiments of this application, the total number of half-wave cycles that need to be heated within the current heating control cycle is the number of heating half-wave cycles corresponding to the Duty order corresponding to the heating duty cycle.

[0016] Preferably, in some embodiments of this application, the number of heating half-wave cycles corresponding to each Duty level corresponds to a first distribution method and a second distribution method within the current heating control cycle; the first distribution method is: the first half-wave cycle that needs to be heated is located in the second half-wave cycle among N half-wave cycles within the current heating control cycle, and the remaining half-wave cycles that need to be heated are distributed after the second half-wave cycle within the current heating control cycle according to a preset rule; the second distribution method is: the first half-wave cycle that needs to be heated is located in the first half-wave cycle among N half-wave cycles within the current heating control cycle, and the remaining half-wave cycles that need to be heated are distributed after the first half-wave cycle within the current heating control cycle according to a preset rule.

[0017] Preferably, in some embodiments of this application, heating control of the fixing unit is performed based on the total number of half-wave periods that need to be heated, including: when the first half-wave period in the previous heating control cycle is a half-wave period that needs to be heated, the fixing unit is heated according to the half-wave periods that need to be heated distributed in a first distribution manner in the current heating control cycle; when the second half-wave period in the previous heating control cycle is a half-wave period that needs to be heated, the fixing unit is heated according to the half-wave periods that need to be heated distributed in a second distribution manner in the current heating control cycle.

[0018] Preferably, in some embodiments of this application, during the heating of the fixing unit in the current heating control cycle, where the half-wave cycles to be heated are distributed in a first distribution or a second distribution, for each half-wave cycle within the current heating control cycle, if the half-wave cycle belongs to the half-wave cycle to be heated, then the solenoid valve is controlled to open at the beginning of the half-wave cycle to heat the fixing unit; if the half-wave cycle does not belong to the half-wave cycle to be heated, then the solenoid valve is controlled to close at the beginning of the half-wave cycle to stop heating the fixing unit.

[0019] Preferably, in some embodiments of this application, N is 14.

[0020] Preferably, in some embodiments of this application, the current temperature value is the average of the initial temperature values ​​of the fixing unit obtained in the most recent n samplings, including this sampling, wherein the time interval between two adjacent samplings is 2ms.

[0021] (III) Beneficial Effects

[0022] The heating control method for the printer fuser unit provided in this application achieves precise calculation of the heating duty cycle by dynamically updating the proportional, integral, and derivative coefficients of the PID control algorithm based on the temperature difference between the current and target temperatures within the heating control cycle. Furthermore, by mapping the heating duty cycle to a duty order and determining the total number of half-wave cycles requiring heating within the current control cycle based on the duty order, fine-grained heating control of the fuser unit is achieved, resulting in rapid temperature response and stable control within each heating cycle. This method effectively reduces the slow response and high energy consumption problems of traditional constant temperature control, while avoiding temperature overshoot and instability caused by simple PWM control. In addition, by distributing the heating power according to half-wave cycles and executing precise switching control, electrical interference and DC bias problems can be reduced, ensuring the stability and reliability of the heating process. Attached Figure Description

[0023] Figure 1 This is a schematic flowchart of a heating control method for a printer fuser unit according to an embodiment of this application;

[0024] Figure 2 This is a schematic diagram of a second distribution of the heating half-wave period in 14 AC voltage half-wave periods when the Duty order corresponds to 4 heating half-wave periods according to one embodiment of this application.

[0025] Figure 3 This is a schematic diagram of the first distribution of the heating half-wave period in 14 AC voltage half-wave periods when the Duty order corresponds to 4 heating half-wave periods according to one embodiment of this application. Detailed Implementation

[0026] To better explain and facilitate understanding of this application, the following detailed description of the application is provided in conjunction with the accompanying drawings and specific embodiments.

[0027] In existing technologies, temperature control for printer fuser units can be mainly categorized into two types:

[0028] The first type is a temperature regulation scheme based on constant temperature control. This scheme uses a temperature sensor to collect the temperature of the fixing unit in real time and maintains a constant temperature by adjusting the power of the heating element. This method can maintain the temperature within a preset range under different printing speeds and environmental conditions, thus ensuring print quality. However, this scheme is highly dependent on the temperature control response speed. When the printer needs to heat up or cool down quickly, the constant temperature control often reacts slowly, making it difficult to achieve rapid adjustment. At the same time, maintaining a constant temperature can easily lead to additional energy consumption and reduced energy efficiency when the printer is idle or under low load.

[0029] The second type is a temperature control scheme based on pulse width modulation (PWM) control. This scheme achieves precise control of heating power by adjusting the pulse width of the heating element, thereby regulating the temperature of the fixing unit. Theoretically, this method can improve the temperature control response speed and power regulation accuracy, but it suffers from temperature overshoot, leading to unstable temperature control. In addition, high-frequency pulse control is prone to causing electrical problems such as electromagnetic interference and DC bias, affecting the safety and reliability of the equipment. Furthermore, in actual printing, temperature fluctuations directly affect print quality.

[0030] To address this, the printer fuser unit heating control method provided in this application dynamically updates the proportional, integral, and derivative coefficients of the PID control algorithm based on the temperature difference between the current and target temperatures within each heating control cycle, achieving precise calculation of the heating duty cycle. Furthermore, it maps the heating duty cycle to a duty order and determines the total number of half-wave cycles requiring heating within the current control cycle based on the duty order, thereby enabling refined heating control of the fuser unit. During the control process, this method dynamically selects the distribution mode of the heating half-waves based on the half-wave distribution of the previous cycle and achieves half-wave level heating control through switching solenoid valves, effectively solving problems such as slow response and high energy consumption in constant temperature control, as well as temperature overshoot and electrical interference in PWM control. In this way, even under conditions of high-speed printing, frequent start-stop, or power adjustment, temperature regulation and power distribution can be independently completed within each heating control cycle, ensuring rapid response, stability, and high efficiency of the fuser unit temperature, thereby improving print quality and overall equipment reliability.

[0031] To better understand the above technical solutions, exemplary embodiments of this application will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of this application are shown in the drawings, it should be understood that this application can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this application can be understood more clearly and thoroughly, and that the scope of this application can be fully conveyed to those skilled in the art.

[0032] Figure 1 This is a schematic flowchart illustrating a heating control method for a printer fusing unit according to an embodiment of this application. Figure 1 As shown, the heating control method for the printer's fusing unit includes:

[0033] For each heating control cycle, the current temperature and target temperature of the fixing unit are acquired, and based on the temperature difference between the current and target temperatures, a PID control algorithm is used to determine the heating duty cycle.

[0034] The proportional coefficient, integral coefficient, and derivative coefficient of the PID control algorithm are updated based on the temperature difference in the corresponding heating control cycle. For example, assuming the target temperature of the fixing unit is 180°C, and the currently acquired temperature is 170°C, the temperature difference is 10°C. The PID control algorithm calculates the heating duty cycle based on this temperature difference to control the heating element to output appropriate power, so that the temperature quickly approaches the target value. If the temperature rises to 175°C in the next cycle, the temperature difference decreases to 5°C, and the PID algorithm automatically reduces the heating duty cycle to achieve a smooth temperature rise and avoid overshoot. In this application, the proportional coefficient (K) of the PID control algorithm... p ), integral coefficient (K) i) and differential coefficients (K d The proportional gain (K) is not fixed, but dynamically adjusted based on the temperature difference during the current heating control cycle. For example, when the temperature difference is large (e.g., 10°C), the proportional gain K is increased. p This allows for rapid heating in response to temperature differences, shortening the heating time; as the temperature difference gradually decreases (e.g., 2°C), the proportionality coefficient K is reduced. p Increase the integral coefficient K i Differential coefficient K d This dynamic update method is used to suppress temperature fluctuations, thereby achieving smooth control. If slight temperature fluctuations occur, the derivative action can suppress overshoot in advance, making temperature control more stable. This dynamic update method can adjust the heating intensity for different temperature differences, achieving a balance between rapid response and smooth control. In the embodiments of this application, by acquiring the difference between the temperature value and the target temperature value in real time and using the PID algorithm to calculate the duty cycle, the heating power can be quickly adjusted in each control cycle, solving the problem of slow response in constant temperature control. Furthermore, by dynamically adjusting the PID parameters, the proportional, integral, and derivative actions change with the temperature difference, adaptively controlling the heating output, avoiding temperature overshoot and fluctuations caused by simple PWM control, and improving temperature control stability.

[0035] Specifically, in this embodiment, the heating control cycle is the length of N half-wave cycles with an AC voltage of 220V, where N is greater than or equal to 2. Assuming the AC grid frequency is 50Hz, a complete AC cycle is 20ms, and each half-wave cycle is 10ms. If N=14 is chosen, the total time of one heating control cycle is 14×10ms. Within this control cycle, the heating duty cycle calculated by the PID algorithm is mapped to a specific duty order, thereby determining the number of half-wave cycles to be heated in this cycle. For example, if the PID calculates a heating duty cycle of 50%, the corresponding duty order might be 7. Therefore, 7 half-wave cycles are selected from these 14 half-wave cycles for heating, with the distribution dynamically adjusted based on the state of the previous cycle.

[0036] In another specific embodiment of this application, when the printer is in a high-load, high-speed printing state, the N value can be increased to cover more half-wave cycles in each control cycle, ensuring smooth heating distribution and fine control. When the printer is in a low-load or small-scale temperature adjustment state, the N value can be decreased to shorten the control cycle and achieve a faster temperature control response. For example, if the ambient temperature is low and the initial temperature difference is large, N=20 can be selected to extend the control cycle and make the PID duty cycle allocation more precise; if the printing speed is slow or the temperature difference is small, N=8 can be selected for more agile control.

[0037] In this embodiment, by dividing the heating control cycle into multiple half-wave cycles, the heating output can be precisely controlled at the micro level, enabling the PID calculation results to quickly match the actual heating behavior, thereby achieving a smooth temperature rise or fall. In addition, N half-wave cycles constitute a control cycle, providing a clear time unit basis for subsequent duty order mapping and half-wave cycle distribution strategies (first distribution method and second distribution method).

[0038] Determining the corresponding Duty level based on the heating duty cycle; in some embodiments of this application, determining the corresponding Duty level based on the heating duty cycle includes: determining a pre-divided duty cycle interval to which the heating duty cycle belongs; determining the corresponding Duty class according to the pre-divided duty cycle interval to which the heating duty cycle belongs, and using the Duty class as the Duty level corresponding to the heating duty cycle.

[0039] In detail, in this embodiment, the heating duty cycle output by the PID control algorithm is a continuous value, such as any decimal between 0% and 100%. To facilitate mapping it to actual heating control behavior, the duty cycle is divided into multiple intervals, each interval corresponding to a "Duty level," thereby achieving discretization and execution of heating control. For example, assuming the current heating control cycle contains N=14 half-wave cycles, the duty cycle range (0%, 100%) can be divided into 14 intervals, each interval having a length of 100%÷N≈7.14%. 0% corresponds to a Duty level of 0. Therefore, if the PID output duty cycle is 12%, it falls into the second interval, corresponding to a Duty level of 2; if the PID output duty cycle is 47%, it falls into the seventh interval, corresponding to a Duty level of 7; if the PID output duty cycle is 88%, it falls into... The thirteenth interval corresponds to a duty cycle of 13. In other words, through this quantization mapping, a continuous "heat power demand" is transformed into a specific "number of heating half-waves." For example, a duty cycle of 2 corresponds to 2 heating half-wave cycles in this control cycle; a duty cycle of 7 corresponds to 7 heating half-wave cycles in this control cycle; and a duty cycle of 13 corresponds to 13 heating half-wave cycles in this control cycle. This method effectively transforms temperature control from an abstract duty cycle into physical-level control (the number of conducting half-wave cycles), thereby achieving a closed-loop temperature control.

[0040] In this embodiment, since the duty cycle output by the PID control algorithm is a continuous floating-point number, while the actual fixing heating action depends on the discrete behavior of whether the AC half-wave is on (heating only occurs after on), it is necessary to discretize the continuous signal. By partitioning the duty cycle and mapping it to a fixed duty order, frequent heating switching caused by floating-point calculation errors or small jitters can be avoided, thereby ensuring the stability of the control signal at the electrical level. This method can prevent power relays, solid-state relays, or solenoid valves from overheating or failing under high-frequency jitter. For example, when the PID output fluctuates slightly between 49.9% and 50.2%, since both are in the same range, the corresponding duty order remains unchanged (e.g., order = 7), and the state will not frequently switch due to small deviations, thus achieving smoother heating control. Secondly, this application achieves precise control of heat distribution through the correspondence between the duty order and the total number of heating half-wave cycles, thereby significantly improving the temperature control accuracy of the fixing unit. Each duty order corresponds to a fixed number of heating half-wave cycles, allowing the amount of heat energy released in each control cycle to be accurately calculated. Furthermore, the duty cycle division method in this application ensures the continuity and smoothness of the heating response. The duty cycle division covers the output range of 0% to 100%, and achieves a natural transition from low power to high power in a continuously increasing manner. When the temperature difference in the fixing unit is detected to gradually decrease, the PID output duty cycle decreases accordingly, automatically falling back to a lower duty cycle, and the heating power decreases step by step. This method avoids overshoot and undershoot phenomena, making the fixing temperature change curve smooth and stable. The paper can be uniformly heated when passing through the fixing unit, preventing quality problems such as local scorching or poor fixing.

[0041] Furthermore, in another embodiment of this application, the Duty order mapping strategy is linked to the number of half-wave cycles (N value) within the control cycle, and can adaptively adjust according to changes in printing speed and ambient temperature. In high-speed printing or low-temperature environments, the N value is automatically increased to improve Duty order resolution and achieve smoother, more refined power regulation; in low-speed or constant-temperature conditions, the N value is decreased to improve response speed, achieving an optimal balance between temperature control accuracy and dynamic response. This dynamic adjustment mechanism enhances the adaptability and robustness of the control algorithm to different operating conditions.

[0042] The duty cycle range (0%, 100%) is pre-divided into N duty cycle intervals, each with a length of 100% / N. Each duty cycle interval corresponds to a unique first duty level, and 0% corresponds to a second duty level. Each duty level corresponds to a specific number of heating half-wave cycles. In this embodiment, the duty cycle range (0%, 100%) is uniformly divided into N intervals, with 0% corresponding to a single duty level and each duty level corresponding to a fixed number of conduction half-wave cycles. This division mechanism mathematically ensures a linear proportional relationship between the output heat power and the duty cycle, thereby creating a direct correspondence between the temperature rise rate and the PID output.

[0043] The total number of half-wave cycles that need to be heated within the current heating control cycle is determined based on the Duty order.

[0044] Specifically, the total number of half-wave cycles that need to be heated within the current heating control cycle is the number of heating half-wave cycles corresponding to the Duty order of the heating duty cycle.

[0045] The number of heating half-wave cycles corresponding to each Duty level corresponds to the first distribution and the second distribution within the current heating control cycle;

[0046] The first distribution method is as follows: the first half-wave period that needs to be heated is located in the second half-wave period among the N half-wave periods in the current heating control period, and the remaining half-wave periods that need to be heated are distributed after the second half-wave period in the current heating control period according to the preset rules.

[0047] The second distribution method is as follows: the first half-wave period that needs to be heated is located in the first half-wave period among the N half-wave periods in the current heating control period, and the remaining half-wave periods that need to be heated are distributed after the first half-wave period in the current heating control period according to the preset rules.

[0048] For example, suppose the heating control cycle contains N=10 AC voltage half-wave cycles. In this case, a duty order can be obtained through the aforementioned steps. For example, if the duty order is 6, then 6 heating half-wave cycles should be conducted within this control cycle. Based on this, to avoid overlapping conduction phases and excessive heat concentration in consecutive cycles, this embodiment employs two distribution methods to arrange the positions of these 6 conduction cycles within the current N half-wave cycles: The first distribution method is: the first conduction cycle is located in the second half-wave cycle, and the remaining 5 conduction half-wave cycles are evenly distributed after the second half-wave cycle according to a preset interval rule (e.g., "interrupting after one non-conducting half-wave cycle" or "equally spaced distribution"). For example, when N=10 and the duty order is 6, the conduction half-wave cycle sequence can be (2, 3, 5, 6, 8, 9), forming a more evenly distributed conduction pattern. The second distribution method: The first conduction cycle is located in the first half-wave cycle, and the remaining five conduction half-wave cycles are also distributed after the first half-wave cycle according to the preset interval rule. For example, when N=10 and Duty order=6, the conduction half-wave cycle sequence can be (1, 2, 4, 5, 7, 8). The distribution method is automatically switched according to the starting conduction position of the previous control cycle (the first or second half-wave cycle), thereby ensuring that the conduction sequences between adjacent control cycles are staggered and avoiding overlapping heating phases in consecutive cycles.

[0049] By alternating between the first and second distribution methods in different control cycles, the heating half-wave cycles are staggered within the phase sequence of the alternating current, effectively avoiding heat concentration caused by overlapping conduction phases within continuous cycles. This staggered distribution avoids temperature overshoot and localized overheating of the fixing drum caused by localized heating concentration, ensuring more uniform heat release in each control cycle and a more balanced temperature distribution on the drum surface. It also reduces the impact of thermal inertia on control accuracy, resulting in a smoother response to PID output changes. Furthermore, because the heating half-wave cycles are dispersed and evenly spaced in each control cycle, the repetitive conduction stress on the solenoid valves or solid-state relays that conduct heating during the half-wave cycles is significantly reduced. Compared to traditional continuous conduction control strategies, this application effectively reduces the instantaneous inrush current and heat generation of the conducting devices (solenoid valves or solid-state relays) through staggered distribution, extending the lifespan of the conducting devices and reducing power grid harmonic interference.

[0050] Heating control of the fixing unit is performed based on the total number of half-wave cycles that need to be heated.

[0051] Specifically, in this embodiment, the heating control of the fixing unit is based on the total number of half-wave periods that need to be heated, including:

[0052] When the first half-wave period in the previous heating control cycle is the half-wave period that needs to be heated, the fixing unit is heated according to the half-wave periods that need to be heated distributed in the first distribution method in the current heating control cycle.

[0053] When the second half-wave period in the previous heating control cycle is the half-wave period that needs to be heated, the fixing unit is heated according to the half-wave period that needs to be heated distributed in the second distribution method in the current heating control cycle.

[0054] In the embodiments of this application, the distribution mode of the current cycle is dynamically selected based on the conduction state of the previous heating control cycle, enabling a smooth transition of power output between heating cycles. Specifically, if each control cycle starts conduction from the same half-wave position, it will cause significant current peaks in the load at the power supply end during periodic changes, resulting in grid inrush and current fluctuations. This application's implementation determines the conduction position of the starting half-wave of the previous cycle (i.e., the half-wave cycle requiring heating) and automatically switches between a first distribution mode and a second distribution mode, causing the conduction start points of adjacent cycles (the start points of the half-wave cycle requiring heating) to alternate in time, thereby achieving a balanced load distribution during different half-wave cycles and avoiding the superposition of conduction peaks. In this way, the output power can achieve a smooth transition during the cycle, significantly reducing grid inrush current, improving power supply stability, and reducing power supply ripple, thus improving reliability. Furthermore, this application's solution can also effectively improve the temperature field uniformity of the fixing unit. When continuous heating half-waves are concentrated at a fixed position, localized high-temperature zones can easily form on the surface of the fixing roller or heating film, resulting in a "hot spot" phenomenon, causing localized overheating or paper burn marks. This application's embodiment alternately switches the distribution phase of the heating half-waves between adjacent control cycles, making the heating waveform uniformly distributed in the time dimension, creating an "odd-even cycle staggered heating" effect. This method achieves uniform heat diffusion on a macroscopic level, avoids localized heat accumulation, significantly improves the temperature distribution stability of the fixing unit, reduces localized thermal stress, and thus makes the paper fixing quality more stable.

[0055] Assume the heating control cycle contains N=14 AC voltage half-wave cycles. Then, through the aforementioned steps, a duty order can be obtained. The duty order corresponds to a heating control cycle that requires heating for 4 heating half-wave cycles. The distribution of these 4 heating half-wave cycles across the 14 AC voltage half-wave cycles can be a second distribution pattern (e.g., ...). Figure 2 (as shown) or the first distribution method (such as) Figure 3 (As shown). Among them, Figure 2 and Figure 3 The half-wave period of the shaded area represents the half-wave period that needs to be heated.

[0056] Preferably, in some embodiments of this application, during the heating of the fixing unit in the current heating control cycle, where the half-wave cycles to be heated are distributed in a first distribution or a second distribution, for each half-wave cycle within the current heating control cycle, if the half-wave cycle belongs to the half-wave cycle to be heated, then the solenoid valve is controlled to open at the beginning of the half-wave cycle to heat the fixing unit; if the half-wave cycle does not belong to the half-wave cycle to be heated, then the solenoid valve is controlled to close at the beginning of the half-wave cycle to stop heating the fixing unit.

[0057] For example, in the current heating control cycle, assuming N=10, meaning the control cycle includes 10 half-wave cycles. When the duty order corresponding to the heating duty cycle calculated by the PID control algorithm is 4, if the duty order of 4 corresponds to a total of 4 heating half-wave cycles that need to be activated in the current heating control cycle, then if the first half-wave cycle in the previous control cycle was a heating half-wave cycle, then the first distribution method is adopted in the current control cycle, that is, starting from the second half-wave cycle, 4 heating half-wave cycles are evenly distributed according to a preset rule. At this time, a judgment is made at the beginning of each half-wave cycle: if the half-wave cycle is marked as a heating half-wave cycle, then an activation signal is immediately output to control the solenoid valve to open, connecting the heating circuit to the power supply; if the half-wave cycle does not belong to a heating half-wave cycle, then the solenoid valve is controlled to close at the beginning of the half-wave, disconnecting the heating circuit. Through this precise half-wave level switching control, the time-division activation and deactivation of the solenoid valve in each heating control cycle is realized.

[0058] By using this on / off control based on half-wave cycles, the output power can be precisely adjusted without changing the control cycle length, resulting in a more sensitive heating response and smoother control of the fixing unit. Secondly, it avoids the current surges and electromagnetic interference caused by frequent high-frequency switching of the solenoid valve. Because the timing of each on / off cycle is strictly aligned with the starting point of the AC half-wave, the current waveform continuity is better, suppressing the generation of high-order harmonics and surge currents, significantly improving power supply stability. Thirdly, it improves the dynamic uniformity of the temperature field in the fixing unit. By alternating between the first and second distribution methods, the starting positions of the heating half-waves in adjacent control cycles are staggered along the time axis, resulting in more uniform heat diffusion in space and time, avoiding temperature differences on the fixing roller surface caused by localized heat accumulation.

[0059] In a specific embodiment of this application, the current temperature value is the average of the initial temperature values ​​of the fixing unit acquired the most recently (n times) including the current sample, where the time interval between two adjacent samples is 2ms. Specifically, in order to obtain a temperature input value reflecting the true thermal state of the fixing unit at the beginning of each heating control cycle, this embodiment adopts a moving average sampling mechanism. Specifically, the control module periodically collects the initial temperature value of the fixing unit from the temperature sensor at a sampling interval of 2ms, and stores the results of the most recently (n times) samples in a temperature cache queue. When a new heating control cycle begins, before performing PID calculation, the most recently (n times) temperature values ​​T1, T2, ..., T3, including the current sample, are first retrieved from the cache. n Calculate the average:

[0060] ;

[0061] and the average temperature value T avg The current temperature value is input to the PID controller as part of the control cycle to determine the heating duty cycle. For example, in one specific implementation, the sampling interval is set to 2ms, and n is 8, meaning that temperature change data within the most recent 16ms is retained. Assuming that a temperature T8 = 178.6°C is collected at the beginning of the current cycle, it is averaged with the previously collected T1~T7 (time span approximately 14ms) to obtain the current temperature value T. avg ≈178.2°C, thus ensuring a stable and accurate temperature input at the beginning of the control cycle.

[0062] In the technical solution of this application, by setting the current temperature value as the average of the initial temperature values ​​of the fixing unit in the most recent n samplings, including this sampling, and using 2ms as the time interval between two adjacent samplings, a stable and reliable temperature input can be obtained immediately at the start of the control cycle. This allows the current temperature value to be determined without waiting for a new multi-sampling process at the start of the control cycle, thus achieving instantaneous temperature determination at the start of the cycle, effectively shortening the response delay and improving control efficiency. Furthermore, it can smooth the fluctuations of the temperature sensor during high-speed sampling, suppress the influence of single sampling errors and short-term noise, and weaken the periodic temperature fluctuations caused by the AC half-wave conduction characteristics. Therefore, the temperature measurement signal exhibits better continuity and stability in the time dimension, providing a smoother input basis for the PID algorithm. Simultaneously, the smooth temperature input makes the changes in the proportional, integral, and derivative terms of the PID controller more gradual, thereby avoiding PID output oscillations or integral accumulation errors caused by instantaneous temperature changes, and optimizing the continuity of duty cycle calculation. In addition, due to the strong thermal inertia characteristics of the fixing roller and heating film themselves, the short-term average temperature reflects the true trend of overall thermal changes more accurately than single-point temperature measurements. By using the sliding average temperature as the PID input, the overall thermal dynamics can be described more accurately, thereby improving the matching degree of the heating control algorithm with the thermal inertia response characteristics of the fixing unit, making the temperature regulation more stable and gentle.

[0063] In this specific implementation, N is 14. That is, each complete heating control cycle corresponds to the time range of 14 AC half-wave signals. Since the pre-divided duty cycle interval length is 100% / N, when N=14, the duty cycle interval is approximately 7.14%, meaning that 15 duty cycles (0% corresponds to one duty cycle) can correspond to different heating half-wave numbers, thus achieving finer power control granularity. Compared to when N is smaller (such as 8 or 10), which only yields coarser power adjustment steps, the interval division of N=14 makes the mapping from duty cycle to the number of heating half-waves smoother. The PID control output can achieve power adjustment within a smaller range of variation, reducing the dispersion of heat output.

[0064] In other embodiments of this application, the proportional coefficient, integral coefficient, and derivative coefficient of the PID control algorithm are updated based on the temperature difference of the corresponding heating control cycle, specifically using the following formula:

[0065] ;

[0066] in, This represents the temperature difference during the current heating control cycle. This indicates the temperature difference change between adjacent heating control cycles; The preset maximum temperature difference (e.g., 30℃); The maximum allowable rate of temperature change (unit: °C / s) is preset. , , These are the basic proportional coefficient, basic integral coefficient, and basic derivative coefficient of the PID control algorithm; , , These are the preset adjustment sensitivity factors; among which, The value range is 0.4 to 0.8; The value range is 0.15 to 0.35; The value range is 0.05~0.2. When the temperature difference... Approaching or exceeding the preset maximum value Or the change in temperature Approaching the maximum allowable rate of change At that time, adjust the sensitivity factor Acting on the proportionality coefficient K p , making K p >K p0 This amplifies the control output, allowing the fixing unit to quickly approach the target temperature and shorten the heating response delay. When the temperature difference... When gradually reduced to near zero, adjust the sensitivity factor. Acting on the integral coefficient K i , making K i A moderate increase is made to compensate for small deviations, ensuring that the temperature accurately approximates the target temperature value, while preventing overshoot caused by excessive accumulation of the integral term. When the rate of change of temperature difference... When it is large, adjust the sensitivity factor. Acting on the differential coefficient K d , making K d >K d0 It enhances the differential suppression effect, responds promptly to rapid temperature changes, effectively reduces temperature oscillations caused by periodic fluctuations in half-wave heating, and achieves smooth temperature control.

[0067] This application achieves dynamic adjustment during the heating, isothermal, and fine-tuning stages by acquiring the temperature difference between the current and target temperatures of the fixing unit within each heating control cycle and adaptively updating the proportional, integral, and derivative coefficients using a PID control algorithm based on this temperature difference. This allows for rapid heating when the temperature difference is large and smooth adjustment when approaching the target temperature, significantly reducing overshoot and oscillation. Simultaneously, the heating duty cycle is mapped to a duty order, and the total number of half-wave cycles requiring heating within the current cycle is determined based on the duty order. Combined with the first or second half-wave distribution and precise control of the solenoid valve, the heating process is continuous and smooth, fully utilizing the thermal inertia of the fixing unit to improve temperature control accuracy and fixing quality. Furthermore, this application's embodiments achieve real-time temperature control and stable output in high-speed printing environments through historical sampling average temperature calculation and rapid PID parameter updates within the cycle, improving energy efficiency and equipment reliability while ensuring print quality.

[0068] In the description of this application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0069] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0070] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first and second features are in direct contact, or that they are in indirect contact through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0071] In the description of this specification, the terms "one embodiment," "some embodiments," "embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0072] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make modifications, alterations, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A heating control method for a printer fuser unit, characterized in that, include: For each heating control cycle, the current temperature value and target temperature value of the fixing unit are obtained, and the heating duty cycle is determined by a PID control algorithm based on the temperature difference between the current temperature value and the target temperature value. The proportional coefficient, integral coefficient and derivative coefficient of the PID control algorithm are updated based on the temperature difference of the corresponding heating control cycle. The current temperature value is the average of the initial temperature values ​​of the fixing unit acquired in the most recent n samplings, including this sampling, where the time interval between two adjacent samplings is 2ms; The corresponding Duty order is determined based on the heating duty cycle. The total number of half-wave cycles that need to be heated within the current heating control cycle is determined based on the Duty order. Heating control of the fixing unit is performed based on the total number of half-wave cycles that need to be heated. Determining the corresponding duty order based on the heating duty cycle includes: determining a pre-defined duty cycle interval to which the heating duty cycle belongs; determining the corresponding duty class according to the pre-defined duty cycle interval to which the heating duty cycle belongs, and using the duty class as the duty order corresponding to the heating duty cycle. The heating control cycle is the time length of N half-wave cycles with an AC voltage of 220V, where N is greater than or equal to 2; Wherein, the total number of half-wave cycles that need to be heated within the current heating control cycle is the number of heating half-wave cycles corresponding to the Duty order corresponding to the heating duty cycle. The number of heating half-wave cycles corresponding to each Duty level corresponds to the first distribution and the second distribution within the current heating control cycle; The first distribution method is as follows: the first half-wave period that needs to be heated is located in the second half-wave period among the N half-wave periods in the current heating control period, and the remaining half-wave periods that need to be heated are distributed after the second half-wave period in the current heating control period according to the preset rules. The second distribution method is as follows: the first half-wave period that needs to be heated is located in the first half-wave period among the N half-wave periods in the current heating control period, and the remaining half-wave periods that need to be heated are distributed after the first half-wave period in the current heating control period according to the preset rules. Heating control of the fixing unit is performed based on the total number of half-wave periods requiring heating, including: When the first half-wave period in the previous heating control cycle is the half-wave period that needs to be heated, the fixing unit is heated according to the half-wave periods that need to be heated distributed in the first distribution method in the current heating control cycle. When the second half-wave period in the previous heating control cycle is the half-wave period that needs to be heated, the fixing unit is heated according to the half-wave period that needs to be heated distributed in the second distribution method in the current heating control cycle. During the heating of the fixing unit in the current heating control cycle, which is distributed in the first or second distribution mode, if the half-wave period to be heated is a half-wave period to be heated, the solenoid valve is opened at the beginning of the half-wave period to heat the fixing unit; if the half-wave period is not a half-wave period to be heated, the solenoid valve is closed at the beginning of the half-wave period to stop heating the fixing unit.

2. The heating control method for the printer fusing unit according to claim 1, characterized in that, in, The duty cycle interval (0%, 100%) is pre-divided into N duty cycle intervals, each with a length of 100% / N; each duty cycle interval corresponds to a unique first duty level, and 0% corresponds to a second duty level; each duty level corresponds to a specific number of heating half-wave cycles.

3. The heating control method for the printer fusing unit according to claim 2, characterized in that, in, N is 14.

4. The heating control method for the printer fusing unit according to claim 3, characterized in that, The current temperature value is the average of the initial temperature values ​​of the fixing unit acquired in the most recent n samplings, including this sampling. The time interval between two adjacent samplings is 2ms.

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