A method and system for thermal printhead power monitoring based on electrical variable measurements

Abstract

The present application relates to the technical field of thermal printhead control, in particular to a thermal printhead power monitoring method and system based on electric variable measurement; the system injects a mixed signal of direct current heating and alternating current detection, and processes the response signal by using double-path separation and quadrature lock-in amplification technology; the core is to solve the in-phase component to accurately determine the instantaneous resistance, and calculate the real instantaneous power and total energy in combination with the direct current; the system adjusts the subsequent heating pulse through a hierarchical correction strategy according to the deviation of the real total energy and the target reference energy; the present application realizes high-speed, high signal-to-noise ratio accurate measurement of the instantaneous resistance during the microsecond pulse.

Description

Technical Field

[0001] This invention relates to the field of thermal printhead control technology, specifically to a method and system for monitoring the power of a thermal printhead based on electrical variable measurement. Background Technology

[0002] In extreme operating conditions, such as extremely low ambient temperatures of -40°C, the resistance of a thermal printhead (TPH) exhibits a strong correlation with its temperature, known as the TCR effect. During the application of microsecond-level electrical pulses, the resistance changes drastically with temperature. The applied electrical power causes a temperature rise, which in turn causes a rise in resistance. However, under constant voltage drive, the increase in resistance, in turn, leads to a decrease in actual power consumption. This is a high-speed nonlinear coupling process. However, traditional power monitoring methods typically assume that the resistance is constant during a pulse or calculate the average power through slow voltage and current sampling. When the rate of change of the TPH resistance, i.e., the load characteristic, is on the same microsecond timescale as the sampling rate of the measurement system, this method based on the static resistance assumption can lead to dynamic load feedback to the measurement reference, causing serious measurement failures.

[0003] This measurement failure leads to the inability to accurately control the true total pulse energy, resulting in problems such as insufficient energy causing blurry printing or excessive energy causing the print head to burn out. This seriously affects the consistency and reliability of the printing quality of the equipment under unattended operating conditions. Therefore, how to accurately measure and control the dynamic changes in instantaneous power and true total energy during microsecond-level pulses has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a method and system for monitoring the power of a thermal printhead based on electrical variable measurement. Specifically, the technical solution of this invention is as follows:

[0005] A method for monitoring the power of a thermal printhead based on electrical variable measurement includes:

[0006] A mixed voltage signal is injected into the thermal printhead, which includes a DC heating pulse and an AC detection signal.

[0007] The response signal of the thermal printhead is collected, and the DC heating current and AC detection response signal are obtained through dual-path separation processing.

[0008] Based on the AC detection response signal, the in-phase component is calculated through quadrature lock-in amplification.

[0009] Obtain the preset system calibration coefficients;

[0010] The instantaneous resistance of the thermal printhead is determined by combining the in-phase component with the system calibration coefficient.

[0011] Calculate the actual instantaneous power based on the DC heating current and instantaneous resistance;

[0012] The true instantaneous power is integrated to determine the true total pulse energy;

[0013] Obtain the preset target reference energy;

[0014] Calculate the energy deviation between the actual total pulse energy and the target reference energy;

[0015] Based on the energy deviation, a preset graded correction strategy is used to adjust the DC heating pulse amplitude or pulse width of the subsequent heating pulse by multiplying the energy deviation by a preset correction ratio gain coefficient.

[0016] Preferably, the dual-path separation process includes:

[0017] DC heating current is obtained from the response signal through a preset low-pass filter;

[0018] The AC detection response signal is obtained from the response signal through a preset bandpass filter.

[0019] Preferably, the energy amplitude of the AC detection signal is preset to be insufficient to produce a thermal effect on the thermal printhead;

[0020] The detection frequency of the AC detection signal is preset to ensure that the AC detection signal is not affected by thermal inertia.

[0021] Preferably, the preset system calibration coefficients are determined through the following steps:

[0022] Disconnect the DC heating pulse;

[0023] Apply a preset precision resistor;

[0024] Measure the in-phase component output value corresponding to the precision resistor;

[0025] The system calibration coefficients were determined by linear regression fitting.

[0026] Preferred, preset target reference energies are stored in a lookup table;

[0027] The target reference energy is preset based on the printing media, printing type, and ambient temperature.

[0028] Preferred, pre-defined hierarchical correction strategies include:

[0029] If the absolute value of the energy deviation is less than or equal to a preset energy threshold, it is determined to be a normal correction.

[0030] Routine corrections include fine-tuning the pulse width.

[0031] Preferably, the preset hierarchical correction strategy also includes:

[0032] If the absolute value of the energy deviation is greater than a preset energy threshold, it is determined to be a serious deviation.

[0033] Significant deviations, including adjustments to the DC heating pulse amplitude and pulse width;

[0034] Serious deviations also include output status warnings.

[0035] A thermal printhead power monitoring system based on electrical variable measurement includes:

[0036] The signal injection module is used to inject a mixed voltage signal into the thermal printhead, which includes a DC heating pulse and an AC detection signal.

[0037] The signal separation module is used to acquire the response signal of the thermal printhead and obtain the DC heating current and AC detection response signal through dual-path separation processing;

[0038] The calculation module is used to calculate the in-phase component based on the AC detection response signal through quadrature phase-locked loop amplification.

[0039] The coefficient acquisition module is used to acquire preset system calibration coefficients;

[0040] The resistance determination module is used to determine the instantaneous resistance of the thermal printhead by combining the in-phase component with the system calibration coefficient.

[0041] The power calculation module is used to calculate the actual instantaneous power based on the DC heating current and instantaneous resistance.

[0042] The energy integration module is used to integrate the actual instantaneous power to determine the actual total pulse energy.

[0043] The benchmark acquisition module is used to acquire the preset target reference energy;

[0044] The deviation calculation module is used to calculate the energy deviation between the actual total pulse energy and the target reference energy;

[0045] The closed-loop correction module is used to adjust the DC heating pulse amplitude or pulse width of the subsequent heating pulse by multiplying the energy deviation by a preset correction ratio gain coefficient according to the energy deviation and through a preset graded correction strategy.

[0046] Preferably, the signal separation module includes:

[0047] The low-pass filter unit is used to obtain the DC heating current from the response signal through a preset low-pass filter;

[0048] The bandpass filter unit is used to obtain the AC detection response signal from the response signal through a preset bandpass filter.

[0049] Compared with the prior art, the present invention has the following beneficial effects:

[0050] 1. This invention achieves high-speed, high signal-to-noise ratio precise measurement of the instantaneous resistance of the thermal printhead during microsecond-level pulses by injecting a mixed signal of DC heating and AC detection, and by employing dual-path separation and orthogonal lock-in amplification technology;

[0051] 2. This invention combines real-time calculated instantaneous resistance and DC heating current to calculate the true instantaneous power and integrate it, thereby accurately obtaining the true total energy applied by a single pulse, solving the problem of power measurement failure caused by the static resistance assumption in traditional methods;

[0052] 3. This invention constructs a closed-loop correction system with the actual total pulse energy as the target by comparing the measured actual pulse total energy with the preset target reference energy, calculating the energy deviation, and adjusting the subsequent heating pulse accordingly, thus ensuring the accurate application of energy;

[0053] 4. This invention employs a graded correction strategy, which can intelligently select to fine-tune the pulse width or forcefully adjust the pulse amplitude and width according to the severity of the energy deviation, and combines it with a lookup table that can adapt to ambient temperature and printing media; this enables the system to converge quickly and stably under extreme conditions such as extremely cold start or heat accumulation, ensuring the consistency of printing quality and operational reliability of unattended equipment under all operating conditions. Attached Figure Description

[0054] The present invention will be further explained below with reference to the accompanying drawings and embodiments:

[0055] Figure 1 This is a flowchart of the method of the present invention;

[0056] Figure 2 This is a structural diagram of the system of the present invention. Detailed Implementation

[0057] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0058] Example 1:

[0059] Please see Figure 1 A method for monitoring the power of a thermal printhead based on electrical variable measurement, comprising:

[0060] A mixed voltage signal is injected into the thermal printhead, which includes a DC heating pulse and an AC detection signal.

[0061] The response signal of the thermal printhead is collected, and the DC heating current and AC detection response signal are obtained through dual-path separation processing.

[0062] Based on the AC detection response signal, the in-phase component is calculated through quadrature lock-in amplification.

[0063] Obtain the preset system calibration coefficients;

[0064] The instantaneous resistance of the thermal printhead is determined by combining the in-phase component with the system calibration coefficient.

[0065] Calculate the actual instantaneous power based on the DC heating current and instantaneous resistance;

[0066] The true instantaneous power is integrated to determine the true total pulse energy;

[0067] Obtain the preset target reference energy;

[0068] Calculate the energy deviation between the actual total pulse energy and the target reference energy;

[0069] Based on the energy deviation, a preset graded correction strategy is used to adjust the DC heating pulse amplitude or pulse width of the subsequent heating pulse by multiplying the energy deviation by a preset correction ratio gain coefficient.

[0070] This embodiment provides a method for monitoring the power of a thermal printhead TPH based on electrical variable measurement;

[0071] The technical background of this invention lies in the fact that, under extreme service conditions, such as extremely low ambient temperatures of -40°C, the heating point resistance of a thermal printhead decreases during operation. With its own temperature It exhibits a strong correlation, i.e., the TCR effect; during the application of the μs-level electrical pulse Strobe, the resistance value... With temperature Drastic changes; applied electrical power lead to rise, The rise led to Rise, and The rise, driven by constant voltage, in turn leads to an increase in the actual power consumed. The descent is a high-speed, nonlinear coupling process.

[0072] Traditional methods typically assume resistance The power is constant during a pulse period, or the average power is calculated by slow V and I sampling. This can lead to dynamic load backlash against the measurement reference when the TPH resistance, i.e., the load characteristic changes at a rate in the μs range, is on the same time scale as the measurement system sampling rate in the μs or ns range, resulting in serious measurement failure.

[0073] The objective of this invention is to accurately measure the transient resistance that dynamically changes during a μs pulse through an active detection and dual-path decoupling method. And combined with real DC heating current Thus, the true instantaneous power can be calculated. and the total energy of the real pulse Ultimately achieve High-precision closed-loop control;

[0074] In this embodiment, the method includes the following steps:

[0075] S1: Inject mixed voltage signal

[0076] This method injects a hybrid voltage signal into the thermal printhead. The hybrid voltage signal is a composite signal whose purpose is to use the signal superposition principle to couple the DC component used for heating and the AC component used for measurement into the same signal, so as to achieve synchronous heating and nanosecond-level instantaneous impedance measurement. The hybrid voltage signal includes a DC heating pulse and an AC detection signal.

[0077] To synchronize heating and measurement, this embodiment constructs a DC-AC hybrid injection voltage model:

[0078] ;

[0079] in, The total voltage signal V injected into TPH, The amplitude V of the DC heating pulse is the main power source for TPH heating, and its amplitude and pulse width are... It determines the total energy; The amplitude can be dynamically adjusted by subsequent closed-loop correction control, see S10; The amplitude V of the AC detection signal is used only as a measurement probe. Its energy is preset to be extremely low, insufficient to produce a thermal effect on the TPH, thereby ensuring that the measurement behavior will not interfere with the heating process of the measured object. The AC detection signal frequency is set to Hz, and the detection frequency is preset to be much higher than the thermal time constant of TPH. For example, the thermal inertia of TPH is on the order of μs, and can be set. The frequency is 10MHz to ensure that the AC detection signal only reflects the instantaneous resistance. And unaffected by thermal inertia;

[0080] S2: Dual-path separation processing

[0081] After injecting the mixed voltage signal, the system acquires the response signal of the thermal printhead, such as the total current flowing through the TPH. The system processes this response signal through dual-path separation. The purpose of dual-path separation is to decouple the DC component carrying power and the AC component carrying instantaneous impedance information in the signal to achieve independent measurement with high bandwidth and high signal-to-noise ratio. This processing is used to obtain the DC heating current. and exchange detection response signals;

[0082] S3: Quadrature lock-in amplification processing

[0083] Based on the acquired AC detection response signal, the system performs quadrature lock-in amplification processing on it; quadrature lock-in amplification is a high-precision signal extraction technique whose purpose is to use a lock-in amplifier to amplify only the detection frequency. The characteristic of being sensitive to in-phase components, from Extracting transient resistance with an extremely high signal-to-noise ratio amidst strong background interference such as pulse and thermal noise. Strictly corresponding signal components; due to the TPH at the detection frequency The lower part is mainly resistive, and its instantaneous resistance The change will be linearly modulated The in-phase component of the signal; therefore, this process ultimately calculates the in-phase component. ;In-phase component It is a DC voltage signal whose amplitude is instantaneously on the order of nanoseconds, reflecting the instantaneous resistance of the TPH. The real changes;

[0084] S4 & S5: Determine instantaneous resistance

[0085] To convert in-phase components Converting to the physical quantity resistance, the system obtains the preset system calibration coefficient. System calibration coefficients It is a key adjustable parameter that characterizes the lock-in amplifier system from voltage V to The conversion factor for the resistance Ω, its unit is Ω. ;

[0086] The system incorporates in-phase components With system calibration coefficients The instantaneous resistance of the thermal printhead is determined by using an instantaneous resistance calculation model. ;

[0087] ;

[0088] in, This is the instantaneous resistance Ω calculated in real time; it is a time-varying resistance. The value that changes dynamically within a μs pulse accurately reflects the TCR effect; For system calibration coefficients The method for obtaining this coefficient is detailed in the embodiments; The in-phase component V of the lock-in amplifier output also varies with time. Dynamically changing;

[0089] S6: Calculate the actual instantaneous power

[0090] The system obtains instantaneous resistance From S5 and DC heating current From S2, the actual instantaneous power is calculated based on the DC heating current and instantaneous resistance. This step is the core of this methodology; it logically connects the two previously independent measurement paths, namely the DC path. and communication paths The calculation model, based on the real instantaneous power P-true, is derived from Joule's law. This avoids the difficulty of synchronously sampling instantaneous V and I;

[0091] ;

[0092] in, The actual instantaneous power is W; The DC heating current A is calculated for path A in S2. The instantaneous resistance Ω of path B in S5 is calculated for the AC path.

[0093] S7: Determine the true total pulse energy

[0094] Print quality, such as dot density, does not depend on instantaneous power. It depends on the total energy applied during a pulse. Therefore, the system provides accurate data on the actual instantaneous power. Integral processing is performed to determine the true total pulse energy. This calculation is performed using the E-pulse total energy calculation model, accumulating the instantaneous power value into the final physical quantity required for closed-loop control. ;

[0095] ;

[0096] in, This is the true total pulse energy J, which is the first time this invention has been able to accurately calibrate the true total energy value of a μs-level dynamic load TPH. The pulse width, i.e. the upper limit of the integration time, is set by the controller or used as a parameter to be adjusted; The actual instantaneous power function W is derived from S6;

[0097] S8 & S9: Calculate Energy Deviation

[0098] In order to perform closed-loop control, the system acquires a preset target reference energy. Target reference energy This refers to the ideal energy value (J) required to ensure specific print quality, such as sharpness. The specific settings are detailed in the embodiments;

[0099] The system calculates the total energy of the actual pulse. Energy from S7 and the target reference energy energy deviation This is the energy deviation calculation model for the closed-loop system error signal, which logically calculates the final output of the measurement system S1-S7. Input to control system S10 Connected;

[0100] ;

[0101] in, Let J be the energy deviation, and let J be the energy deviation. This will serve as the basis for decision-making in the subsequent graded correction strategy S10; The target reference energy is J; The true total pulse energy is J;

[0102] S10: Closed-loop correction

[0103] The system is based on energy deviation From S9, through a preset graded correction strategy, the amplitude of the DC heating pulse of the subsequent heating pulse is adjusted by multiplying the energy deviation by a preset correction ratio gain coefficient. or pulse width The graded correction strategy is a nonlinear control method designed to adjust the control based on deviations. Depending on the severity, different corrective actions of varying degrees may be taken, such as fine-tuning. Or emergency adjustment To achieve rapid convergence and system stability; The signal is then fed back to the control system for reverse adjustment and correction of S1. Model Components and S7 In the model The upper limit, thus forming a complete system based on To create a negative feedback loop for monitoring targets;

[0104] This embodiment employs an active detection method combining DC and AC signals, utilizing a high-frequency AC signal amplified via a lock-in amplifier to rapidly calculate the instantaneous resistance, which varies on the order of μs. The heating current was measured using a DC signal. ;pass Synthesize the instantaneous power and integrate to obtain the true total energy. Ultimately, the goal of Closed-loop control;

[0105] The core advantage lies in the fact that this invention solves the technical problem that the TPH resistor changes rapidly due to the TCR effect in extreme environments such as -40°C, which causes the traditional power measurement based on the static resistance assumption to fail severely. It is the first to achieve high-precision, high signal-to-noise ratio real-time monitoring and closed-loop correction of the true total energy of the μs-level heating pulse, ensuring the consistency of printing quality under extreme temperature differences and mixed printing rates, such as unattended equipment, and preventing equipment failure caused by insufficient energy blurring or excessive energy burnout.

[0106] Example 2:

[0107] Dual-path separation processing includes:

[0108] DC heating current is obtained from the response signal through a preset low-pass filter;

[0109] The AC detection response signal is obtained from the response signal through a preset bandpass filter.

[0110] This embodiment is a specific implementation of the dual-path separation process S2 in Embodiment 1;

[0111] In this embodiment, the dual-path separation process includes:

[0112] The DC heating current is obtained from the response signal through a preset low-pass filter; the purpose of the low-pass filter is to filter out high frequencies. Alternating current is detected for both AC signals and noise; only the high-energy DC heating current used for heating is retained. The component enables accurate measurement of the DC path path A;

[0113] An AC detection response signal is obtained from the response signal through a preset bandpass filter; the center frequency of the bandpass filter is preset to [value missing]. For example, 10MHz, its purpose is to filter out low frequencies. DC heating pulses and broadband noise will only affect the load. The weak AC detection response signal of the information is extracted through path B and sent to the subsequent quadrature lock-in amplifier S3;

[0114] By combining high-pass and low-pass / band-pass filters, this embodiment physically decouples the DC power path and the AC measurement path; this allows the system to simultaneously measure the high-energy DC component. To perform precise measurements, and to detect weak AC signals that reflect instantaneous resistance. Narrowband lock-in amplification was used to resolve the technical contradiction between high bandwidth measurement and high signal-to-noise ratio.

[0115] Example 3:

[0116] The energy amplitude of the AC detection signal is preset to be insufficient to produce a thermal effect on the thermal printhead;

[0117] The detection frequency of the AC detection signal is preset to ensure that the AC detection signal is not affected by thermal inertia.

[0118] This embodiment is a concretization of the parameter constraints of the AC detection signal S1 in Embodiment 1. These two constraints are the physical premises for the success of this method.

[0119] The energy amplitude of the AC detection signal is preset to be insufficient to produce a thermal effect on the thermal printhead;

[0120] Energy amplitude It was set to be extremely low to ensure its energy percentage was relatively low. Negligible; the technical motivation behind this design is to ensure that the signal serves solely as a measurement probe, and its injection does not affect the instantaneous temperature of the TPH. This generates interference; this ensures The instantaneous resistance measured is entirely due to the real thermal effect driven by Vd, rather than the measurement distortion introduced by the measurement signal Va itself;

[0121] The detection frequency of the AC detection signal is preset to ensure that the AC detection signal is not affected by thermal inertia;

[0122] Detection frequency The thermal time constant, or thermal inertia, is set much higher than TPH, typically on the order of μs, for example... The chosen frequency was 10MHz; the technical motivation for this high-frequency detection was the physical temperature of the TPH. and resistance Unable to follow ultra-high frequency fluctuations of 10MHz, therefore the AC detection signal... Only by Modulated by the current value, rather than by The rate of change of this factor affects the lock-in amplifier's instantaneous solution at any nanosecond level; this ensures that the lock-in amplifier can solve instantaneously at any nanosecond level. All of them are against A precise snapshot of the corresponding actual resistance value;

[0123] Through the Amplitude and By precisely constraining the frequency, this embodiment ensures zero interference between the AC probe and the DC heating process of the measured object, achieving high-fidelity instantaneous resistance measurement, which is crucial for subsequent accurate calculations. and The physical premise.

[0124] Example 4:

[0125] The preset system calibration coefficients are determined through the following steps:

[0126] Disconnect the DC heating pulse;

[0127] Apply a preset precision resistor;

[0128] Measure the in-phase component output value corresponding to the precision resistor;

[0129] The system calibration coefficients were determined by linear regression fitting.

[0130] This embodiment uses the preset system calibration coefficients from Embodiment 1. The method for obtaining S4 is specified, and this step is performed before the system leaves the factory or during the maintenance cycle;

[0131] Preset system calibration coefficients Determined through the following steps:

[0132] Disconnecting the DC heating pulse is intended to stop the heating process. The signal is applied to ensure that the TPH is in a cold, unheated state or at a specific reference temperature. ;

[0133] Apply a series of standard resistors with known resistance values ,For example It is used to replace TPH loads;

[0134] Measurements are applied to each At that time, the corresponding in-phase component of the lock-in amplifier output ,correspond At this time, the system only sends... injection AC detection signal;

[0135] The system is based on the acquired multiple sets of data points Through the and Perform linear regression fitting to determine System calibration coefficients in the model ;

[0136] This embodiment provides a precise and reproducible calibration method for determining the calibration of a lock-in amplifier system from... To physical resistance Conversion coefficient This eliminates measurement errors caused by differences in electronic components, temperature drift, and other factors, ensuring accuracy. The absolute accuracy of this core solution formula S5.

[0137] Example 5:

[0138] The preset target reference energy is stored in a lookup table;

[0139] The target reference energy is preset based on the printing media, printing type, and ambient temperature.

[0140] This embodiment uses the target reference energy preset in Embodiment 1. The specific basis for S8's design;

[0141] The preset target reference energy is stored in a lookup table; a lookup table (LUT) is an efficient data access structure; the system controller queries this LUT before executing the print task to obtain the target reference energy. ;

[0142] The target reference energy is preset based on the printing media, the type of printing data, and the ambient temperature; target reference energy It is a key set of adjustable parameters whose values ​​are based on the energy required to ensure optimal print quality such as sharpness and contrast;

[0143] Printing media: Thermal paper of different thicknesses or materials, each requiring different amounts of energy to develop color. different;

[0144] Print data types: High print rates, such as data digest QR codes, can lead to TPH heat buildup, requiring... Lower; low printing rates result in heat loss from sensor readings, requiring... High;

[0145] Ambient temperature: This is a critical factor; when starting at -40°C, the TPH is in an extremely low cold-state resistance, requiring extremely high startup energy. High value; at 5°C or higher, The value decreases accordingly;

[0146] The value is the optimal value set based on experience after conducting a large number of print quality tests under different combinations of the above operating conditions, such as printing QR codes in a -40°C environmental chamber.

[0147] By establishing a multi-dimensional The lookup table in this embodiment enables the target of closed-loop control. It can dynamically adapt to complex service conditions, including media, data, and temperature; this ensures that the S10 control system is always pursuing the correct energy target, which is a prerequisite for achieving consistent print quality under all operating conditions.

[0148] Example 6:

[0149] The preset hierarchical correction strategy includes:

[0150] If the absolute value of the energy deviation is less than or equal to a preset energy threshold, it is determined to be a normal correction.

[0151] Routine corrections include fine-tuning the pulse width.

[0152] This embodiment is a concretization of the first-level conventional correction of the preset hierarchical correction strategy S10 in Embodiment 1;

[0153] The preset hierarchical correction strategy includes:

[0154] If the absolute value of the energy deviation is less than or equal to a preset energy threshold, it is determined to be a normal correction; the preset energy threshold... ,For example The 10% is a tolerance window, set empirically after printing quality tests in extreme environments such as -40°C.

[0155] The logic is: Right now near This situation is judged as a routine correction, and the system considers it to be normal heat accumulation or environmental fluctuations.

[0156] Routine corrections include fine-tuning the pulse width;

[0157] Strategy: The control strategy is to fine-tune the pulse width. That is, the upper limit of the integral in S7; for example, if If the energy is insufficient, slightly increase the energy of the next pulse. ;if If there is a slight excess of energy, the decrease will be slight. Specifically, this fine-tuning can be achieved through proportional control, for example, the pulse width of the next heating pulse. Based on the current pulse width and energy deviation To determine: ;in, This is the preset standard correction proportional gain coefficient, and its unit is, for example, . The coefficient value was calibrated experimentally to ensure that the system converges stably within the normal correction interval;

[0158] By defining a regular correction range, this embodiment achieves smooth adjustment of normal system fluctuations; only adjusting It is a gentle control method that avoids problems caused by minor deviations. Frequent adjustments The potential for system oscillations due to amplitude increases the stability of closed-loop control.

[0159] Example 7:

[0160] The preset graded correction strategy also includes:

[0161] If the absolute value of the energy deviation is greater than a preset energy threshold, it is determined to be a serious deviation.

[0162] Significant deviations, including adjustments to the DC heating pulse amplitude and pulse width;

[0163] Serious deviations also include output status warnings.

[0164] This embodiment further defines the preset graded correction strategy by adding a definition of a second-level severe deviation based on embodiment 6.

[0165] The preset graded correction strategy also includes:

[0166] If the absolute value of the energy deviation is greater than a preset energy threshold, it is determined to be a serious deviation.

[0167] The logic is: This situation is considered a serious deviation.

[0168] Scenario: This usually corresponds to two extreme working conditions: 1) Severe energy shortage, for example, TPH fails to start at an extremely cold state of -40°C; or 2) There is a serious energy surplus, for example, due to the accumulation of heat caused by continuous printing of QR codes;

[0169] Significant deviations, including adjustments to the DC heating pulse amplitude and pulse width;

[0170] Strategy: At this point, only minor adjustments are needed. This is no longer sufficient to quickly correct the deviation; the control strategy has been upgraded to a powerful correction: simultaneously adjusting the amplitude of the DC heating pulse. For example, improving during cold start and pulse width For example, significant adjustments Specifically, this adjustment can employ a more aggressive multivariate proportional control strategy, such as adjusting the amplitude of the next heating pulse. and pulse width It can be determined as follows: and ;in, and To correct the proportional gain coefficient for the preset severe deviation; to ensure unit ( )consistency, The unit should be preset as These coefficient values ​​were calibrated experimentally; these coefficient values ​​were typically set to be greater than the conventional gain in Example 6. ,or It has a significant amplitude to achieve rapid and powerful correction of severe deviations;

[0171] Serious deviations also include output status warnings;

[0172] Strategy: When a serious deviation is detected, the system simultaneously outputs a status warning signal to the main control system, such as the central control room of an unattended site, indicating unstable printing energy.

[0173] This embodiment achieves nonlinear control by introducing a second-order correction for severe deviations; it enables the system to withstand drastic changes in operating conditions such as -40°C cold start or sudden increases in heat by adjusting... and It quickly and powerfully corrects energy deviations to prevent printing failures; at the same time, the status warning function enhances the autonomous diagnosis and maintenance capabilities of unattended equipment.

[0174] Example 8:

[0175] Please see Figure 2 A thermal printhead power monitoring system based on electrical variable measurement includes:

[0176] The signal injection module is used to inject a mixed voltage signal into the thermal printhead, which includes a DC heating pulse and an AC detection signal.

[0177] The signal separation module is used to acquire the response signal of the thermal printhead and obtain the DC heating current and AC detection response signal through dual-path separation processing;

[0178] The calculation module is used to calculate the in-phase component based on the AC detection response signal through quadrature phase-locked loop amplification.

[0179] The coefficient acquisition module is used to acquire preset system calibration coefficients;

[0180] The resistance determination module is used to determine the instantaneous resistance of the thermal printhead by combining the in-phase component with the system calibration coefficient.

[0181] The power calculation module is used to calculate the actual instantaneous power based on the DC heating current and instantaneous resistance.

[0182] The energy integration module is used to integrate the actual instantaneous power to determine the actual total pulse energy.

[0183] The benchmark acquisition module is used to acquire the preset target reference energy;

[0184] The deviation calculation module is used to calculate the energy deviation between the actual total pulse energy and the target reference energy;

[0185] The closed-loop correction module is used to adjust the DC heating pulse amplitude or pulse width of the subsequent heating pulse by multiplying the energy deviation by a preset correction ratio gain coefficient according to the energy deviation and through a preset graded correction strategy.

[0186] This embodiment provides a thermal printhead power monitoring system based on electrical variable measurement. This system is used to execute the method of Embodiment 1. Each module of this system is set up to implement the corresponding method steps in Embodiment 1.

[0187] A thermal printhead power monitoring system based on electrical variable measurement includes:

[0188] The signal injection module is designed to generate and inject a mixed voltage signal into the thermal printhead. In this embodiment, it is a signal generator that mixes voltage signals including DC heating pulses and AC detection signals. This corresponds to S1;

[0189] The signal separation module aims to decouple the power and measurement signals; it is used to acquire the response signal of the thermal printhead and obtain the DC heating current through dual-path separation processing. And the AC detection response signal; this corresponds to S2;

[0190] The calculation module aims to extract instantaneous resistance information; it is used to calculate the in-phase component based on the AC detection response signal through quadrature lock-in amplification, for example, by incorporating a lock-in amplifier chip. This corresponds to S3;

[0191] The coefficient acquisition module aims to provide a calibration benchmark; it is used to acquire preset system calibration coefficients. In this embodiment, it is a memory unit used to store the data obtained after calibration using the method of embodiment 4. Value; This corresponds to S4;

[0192] The resistance determination module is designed to calculate instantaneous resistance; it is used to incorporate in-phase components. With system calibration coefficients According to the formula Determine the instantaneous resistance of the thermal printhead. This corresponds to S5;

[0193] The power calculation module aims to synthesize actual power; it is used to calculate power based on DC heating current. and instantaneous resistance According to the formula Calculate the true instantaneous power This corresponds to S6;

[0194] The energy integration module aims to accumulate total energy; it is used to calculate the actual instantaneous power. Perform integration according to the formula. Determine the true total pulse energy This corresponds to S7;

[0195] The reference acquisition module aims to provide control targets; it is used to acquire preset target reference energy. In this embodiment, it is a lookup table (LUT) reading unit that reads the operating medium, data, and temperature according to embodiment 5. This corresponds to S8;

[0196] The deviation calculation module is designed to calculate control error; it is used to calculate the total energy of the actual pulse. With the target reference energy energy deviation This corresponds to S9;

[0197] The closed-loop correction module is designed to perform feedback control; it is used to adjust for energy deviation. By using a preset graded correction strategy, such as in Examples 6 and 7, the amplitude of the DC heating pulse of the subsequent heating pulse is adjusted. or pulse width This module is a controller such as an MCU or FPGA that receives... As input, and output and The adjustment signal is fed back to the signal injection module and the energy integration module; this corresponds to S10;

[0198] The system in this embodiment, through the coordinated operation of its various modules, constitutes a complete control loop of active detection, dual-path separation, phase-locked loop calculation, energy integration, and closed-loop correction. This system can monitor and control the actual total energy applied by the TPH during μs-level pulses in real time and with high precision in extreme environments such as -40°C. Overcoming dynamic load The measurement challenges caused by drastic changes ensured the printing quality and reliability of the unattended equipment under all operating conditions.

[0199] Example 9:

[0200] The signal separation module includes:

[0201] The low-pass filter unit is used to obtain the DC heating current from the response signal through a preset low-pass filter;

[0202] The bandpass filter unit is used to obtain the AC detection response signal from the response signal through a preset bandpass filter.

[0203] This embodiment is a specific embodiment of the hardware configuration of the signal separation module in Embodiment 8;

[0204] According to Embodiment 8, a thermal printhead power monitoring system based on electrical variable measurement includes a signal separation module, which specifically comprises:

[0205] The purpose of the low-pass filter unit is to extract the DC power component; it is used to obtain the DC heating current from the response signal by passing it through a preset low-pass filter circuit, such as an RC low-pass filter or an active low-pass filter. ;

[0206] The purpose of a bandpass filter unit is to extract AC measurement signals; it is used to pass the signals through a preset bandpass filter circuit, for example, one with a center frequency precisely set. An LC or active bandpass filter is used to obtain the AC detection response signal from the response signal and transmit it to the solution module, i.e., the lock-in amplifier.

[0207] These two units work together to physically split the hybrid response signal into two parts, thus realizing the method of Example 2;

[0208] Through the physical implementation of low-pass and band-pass filtering units, the signal separation module can effectively separate high-energy DC signals and weak high-frequency AC signals, sending them to their respective optimal processing links: DC measurement vs. lock-in amplification. This ensures that the lock-in amplifier in the decoding module will not be affected by high-energy signals. The pulse is saturated, and the power calculation module will not be saturated. High-frequency noise interference greatly improves the overall system, especially and The measurement signal-to-noise ratio and accuracy.

[0209] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method of thermal printhead power monitoring based on electrical variable measurements, characterized by, The method comprises the following steps: injecting a mixed voltage signal into the thermal print head, the mixed voltage signal comprising a direct current heating pulse and an alternating current detection signal; acquiring a response signal of the thermal print head and obtaining a direct current heating current and an alternating current detection response signal through double-path separation processing; based on the alternating current detection response signal, calculating an in-phase component through quadrature phase detection processing; obtaining a preset system calibration coefficient; combining the in-phase component and the system calibration coefficient to determine an instantaneous resistance of the thermal print head; based on the direct current heating current and the instantaneous resistance, calculating a real instantaneous power; integrating the real instantaneous power to determine a real total pulse energy; obtaining a preset target reference energy; calculating an energy deviation between the real total pulse energy and the target reference energy; according to the energy deviation, adjusting a direct current heating pulse amplitude or a pulse width of a subsequent heating pulse through a preset hierarchical correction strategy by multiplying the energy deviation by a preset correction proportional gain coefficient.

2. A method of power monitoring of a thermal printhead based on measurement of an electrical variable as claimed in claim 1, characterized in that, The double-path separation processing comprises the following steps: obtaining the direct current heating current from the response signal through a preset low-pass filter; obtaining the alternating current detection response signal from the response signal through a preset band-pass filter.

3. A method of power monitoring of a thermal printhead based on measurement of an electrical variable as claimed in claim 1, wherein, The energy amplitude of the alternating current detection signal is preset to be insufficient to cause a thermal effect on the thermal print head; the detection frequency of the alternating current detection signal is preset to ensure that the alternating current detection signal is not affected by thermal inertia.

4. The method of claim 1, wherein the method further comprises: The preset system calibration coefficient is determined through the following steps: turning off the direct current heating pulse; applying a preset precision resistor; measuring an in-phase component output value corresponding to the precision resistor; determining the system calibration coefficient through linear regression fitting processing.

5. A method for power monitoring of a thermal printhead based on measurement of an electrical variable as claimed in claim 1, wherein, The preset target reference energy is stored in a lookup table; the target reference energy is preset according to the printing medium, the printing data type, and the environmental temperature.

6. A method of power monitoring of a thermal printhead based on measurement of an electrical variable as claimed in claim 1, wherein, The preset hierarchical correction strategy comprises the following steps: in response to an absolute value of the energy deviation being less than or equal to a preset energy threshold, determining a regular correction; the regular correction comprises fine-tuning the pulse width.

7. A method of power monitoring of a thermal printhead based on measurement of an electrical variable as claimed in claim 6, characterized in that, The preset hierarchical correction strategy further comprises the following steps: in response to the absolute value of the energy deviation being greater than the preset energy threshold, determining a severe deviation; the severe deviation comprises adjusting the direct current heating pulse amplitude and the pulse width; the severe deviation further comprises outputting a state warning.

8. A thermal printhead power monitoring system based on electrical variable measurements, characterized by, The method comprises the following steps: a signal injection module for injecting a mixed voltage signal into the thermal print head, the mixed voltage signal comprising a direct current heating pulse and an alternating current detection signal; a signal separation module for acquiring a response signal of the thermal print head and obtaining a direct current heating current and an alternating current detection response signal through double-path separation processing; a calculation module for calculating an in-phase component based on the alternating current detection response signal through quadrature phase detection processing; a coefficient acquisition module for obtaining a preset system calibration coefficient; a resistance determination module for combining the in-phase component and the system calibration coefficient to determine an instantaneous resistance of the thermal print head; a power calculation module for calculating a real instantaneous power based on the direct current heating current and the instantaneous resistance; an energy integration module for integrating the real instantaneous power to determine a real total pulse energy; a reference acquisition module for obtaining a preset target reference energy; a deviation calculation module for calculating an energy deviation between the real total pulse energy and the target reference energy; The closed-loop correction module is configured to adjust the direct current heating pulse amplitude or pulse width of the subsequent heating pulse by multiplying the energy deviation by a preset correction proportional gain coefficient according to the energy deviation through a preset hierarchical correction strategy.

9. A thermal printhead power monitoring system based on measurement of an electrical variable as claimed in claim 8, wherein, The signal separation module comprises: A low-pass filter unit is configured to obtain the direct current heating current from the response signal through a preset low-pass filter. A band-pass filter unit is configured to obtain the alternating current detection response signal from the response signal through a preset band-pass filter.

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