A wide-format thermal printing system, apparatus and method of dynamic calibration of a printing system

Abstract

The application discloses a wide-format thermal printing system, device and dynamic calibration method of the printing system, which comprises a main control module, a displacement calibration module and a printing execution module. The printing execution module comprises at least two head-to-tail adjacent printheads, and a joint seam is formed between the adjacent printheads. The displacement calibration module comprises a first detection module and a first compensation module. The first detection module is arranged on a stress conduction path of the printhead, is used for collecting position offset information of the two adjacent printheads and transmitting the position offset information to the main control module, and the main control module outputs offset control information to the first compensation module according to the position offset information. The first compensation module is pressed on the surface of the printhead away from the printing medium, responds to the offset control information and adjusts and calibrates the positions of the two adjacent printheads. The application can adapt to different printing media, adapt the pressure of the joint area and the single printhead area to the current medium, prevent printing density difference and improve the wide-format printing quality.

Description

Technical Field

[0001] This application relates to the field of printing technology, and in particular to a wide-format thermal printing system, apparatus, and dynamic calibration method for the printing system. Background Technology

[0002] In the field of thermal transfer printing technology, as the demand for printing width continues to increase in industries such as advertising printing, textile printing, and packaging material printing, the width limitation of a single thermal printhead has become a key factor restricting wide-format printing applications. As a result, multi-printhead splicing technology has become the mainstream implementation path for wide-format thermal transfer printing systems, widely serving various large-size printing production scenarios.

[0003] Currently, while wide-format thermal transfer printing systems on the market generally adopt multi-printhead splicing solutions, in actual operation, due to limitations in technical design, common problems still exist that affect print quality and equipment durability. From the perspective of existing industry practices, optimization directions for multi-printhead splicing vary: some solutions achieve fixed splicing of printheads through mechanical positioning structures, which has certain advantages in cost control, but struggles to guarantee continuous and accurate alignment of the spliced ​​area in the face of external interference during the printing process (such as equipment vibration and media transmission fluctuations); other solutions attempt to adjust the printhead position through motor drive to adapt to different printing conditions, but deficiencies in the feedback mechanism design result in the accuracy and dynamic adaptability of position adjustment failing to meet diverse printing needs; still other solutions rely on software algorithms to optimize print data, attempting to improve the visual effect of the spliced ​​area, but cannot fundamentally solve the physical deviations and uneven stress issues at the hardware level, ultimately potentially affecting the stability of print quality.

[0004] In addition, existing multi-printhead splicing systems still have room for improvement in terms of core functional adaptability: On the one hand, during the collaborative work of multiple printheads, the differences in signal transmission and device response characteristics can easily lead to inconsistent heating control timing, especially in high-speed printing scenarios, where such timing deviations have a more significant impact on the image quality of the spliced ​​area; on the other hand, the pressing mechanism in the printing process mostly adopts a fixed structure design, making it difficult to flexibly adjust the pressure parameters according to the actual characteristics of the printing medium. This may not only lead to differences in printing effects in different areas, but also cause additional wear and tear on the printheads with long-term use, affecting the overall lifespan of the equipment.

[0005] In summary, the existing multi-printhead splicing technology of wide-format thermal transfer printing systems is insufficient to meet the comprehensive requirements of high precision, high stability, and multi-media compatibility in wide-format printing scenarios. Therefore, there is an urgent need for a high-precision seamless splicing thermal transfer printing system that can solve the above problems in order to break through the existing technological bottlenecks. Summary of the Invention

[0006] To address the aforementioned technical problems, this application provides a wide-format thermal printing system, apparatus, and a dynamic calibration method for the printing system.

[0007] Firstly, this application provides a wide-format thermal printing system, which adopts the following technical solution:

[0008] A wide-format thermal printing system includes: a main control module, a displacement calibration module, and a printing execution module. The printing execution module includes at least two printheads that are adjacent to each other, forming a seam between them. The displacement calibration module includes a first detection module and a first compensation module. The first detection module is positioned on the force transmission path of the printheads and is used to collect position offset information of the two adjacent printheads and transmit it to the main control module. The main control module outputs offset control information to the first compensation module based on the position offset information. The first compensation module is pressed against the surface of the printheads facing away from the printing medium and adjusts the position of the two adjacent printheads in response to the offset control information. The position offset information includes a longitudinal pressure value, and the position calibration adjustment includes longitudinal position adjustment. The first detection module is used to detect the longitudinal pressure value of the two adjacent printheads, and the first compensation module is used to adjust the longitudinal position of the two adjacent printheads based on the longitudinal pressure value.

[0009] By adopting the above technical solution, this solution addresses the problem of uneven pressure distribution during multi-printhead splicing in existing wide-format thermal printing systems, which leads to blurred printed images and localized wear. It constructs a longitudinal pressure closed-loop adjustment mechanism consisting of a first detection module and a first compensation module. The first detection module captures the longitudinal pressure values ​​of adjacent printheads in real time, providing precise pressure feedback to the main control module. The first compensation module dynamically adjusts the longitudinal position of the printhead based on the feedback pressure value. This solution not only specifically addresses the problem of blurred printed images and localized wear caused by uneven pressure during multi-printhead splicing in existing wide-format thermal printing systems, but also overcomes the limitation of non-adjustable pressure in the fixed pressing mechanism of traditional systems. It can adapt to printing media of different thicknesses and hardnesses, ensuring that the pressure in the splicing area and the single printhead area is always adapted to the current media, preventing differences in printing density, media damage, and excessive localized wear of the printhead. This improves the uniformity of wide-format printed images, extends the lifespan of the printhead, and is suitable for scenarios with high printing quality requirements, such as advertising printing and textile printing.

[0010] Optionally, the first detection module is a pressure sensor, and at least one pressure sensor is provided for each printhead.

[0011] By adopting the above technical solution, the pressure sensor has high sensitivity and can accurately capture the longitudinal pressure changes of a single printhead, preventing pressure feedback deviation caused by shared detection elements. Each printhead is equipped with at least one pressure sensor, which can realize independent monitoring of the pressure status of each printhead, ensuring that the main control module can output offset control information in a targeted manner, further improving the accuracy of longitudinal position adjustment and reducing pressure interference between multiple printheads.

[0012] Optionally, the first compensation module includes a pressing assembly, which includes a first guide rail, a first drive motor, a second drive motor, and at least two linear actuators. The linear actuators are configured one-to-one with the printhead. The body of the linear actuator is fixed to the first guide rail, and the end of the telescopic rod of the linear actuator is pressed against the surface of the printhead facing away from the printing medium. The first drive motor is used to drive the first guide rail to move in a direction perpendicular to the surface of the printing medium, and the second drive motor is used to drive the telescopic rod to extend and retract.

[0013] By adopting the above technical solution, the guide rail, drive motor, and linear actuator structure of the pressing assembly achieve multi-dimensional adjustment. For example, in one embodiment, the first drive motor can be a stepper motor with an adjustment accuracy of ±0.1mm. It drives the first guide rail to move the entire linear actuator longitudinally, achieving coarse adjustment of the longitudinal position of the print head. The second drive motor is a servo motor with an adjustment accuracy of ±0.01mm. The second drive motor drives the telescopic rod to extend and retract, achieving fine adjustment of the longitudinal position of a single print head. The two work together to meet the pressure adjustment accuracy requirements of different media (such as thin PET film requiring fine adjustment, and thick cotton and linen fabric requiring a combination of coarse and fine adjustment). The linear actuator corresponds one-to-one with the print head, ensuring that the adjustment of each print head is independent and controllable. It can quickly respond to the feedback signal of the pressure sensor, dynamically correct pressure deviation, and reduce printing defects caused by pressure fluctuations in the splicing area.

[0014] Optionally, linear actuators include electric linear actuators, voice coil motors, piezoelectric ceramic actuators, or pneumatic or hydraulic cylinders with servo control.

[0015] By adopting the above technical solutions, a variety of linear actuator types are available to suit different printing scenarios. Nitrogen spring cylinders (pneumatic cylinders) have stable spring force output and are suitable for textile printing scenarios with high pressure stability requirements. Hydraulic spring cylinders (hydraulic cylinders) have high adjustment precision and are suitable for high-precision printing needs such as advertising printing, as well as batch printing scenarios such as packaging materials, taking into account both practicality and scenario compatibility.

[0016] Optionally, the displacement calibration module also includes a second detection module and a second compensation module. The second detection module is located on the bodies of two adjacent printheads and near the seam. It is used to collect the lateral offset at the seam and transmit it to the main control module. The second compensation module includes a third drive motor and a second guide rail. The main control module receives the lateral offset and controls the third drive motor to drive the second guide rail to move along the width direction of the printing medium, thereby moving the printhead to adjust the gap of the seam.

[0017] The above technical solution can specifically address the image seam problem caused by the physical gap between the multiple printheads in existing wide-format thermal transfer printing systems. The newly added second detection module and second compensation module form a closed-loop adjustment mechanism for lateral offset. This mechanism can achieve precise single-time calibration during system installation and debugging to ensure no initial gaps, and can also dynamically correct offsets in real time during printing (such as offsets caused by media tension fluctuations or printhead deformation). This effectively overcomes the shortcomings of existing static splicing that cannot adapt to dynamic printing displacement, achieving seamless splicing of wide-format thermal transfer printing images throughout the entire process, and meeting the continuous demand for splicing accuracy in advertising printing, textile printing, and other scenarios.

[0018] Optionally, the second detection module includes an optical sensor, a laser displacement sensor, a visual image sensor, or a grating ruler displacement sensor.

[0019] By adopting the above technical solutions, various types of sensors can meet different accuracy requirements. Optical sensors and laser displacement sensors have fast response speeds and are suitable for high-speed printing scenarios. Visual image sensors can directly capture images of the splicing seams, making it easy for the main control module to intuitively judge the offset status. Grating ruler displacement sensors have high accuracy and are suitable for high-end printing scenarios such as silk digital thermal transfer printing with extremely high splicing accuracy requirements, further broadening the application scope of the system.

[0020] Optionally, a signal preprocessing module is also included. The signal preprocessing module is electrically connected between the main control module and the displacement calibration module. The signal preprocessing module includes a time delay compensation module. The time delay compensation module is used to receive the position offset information of the first detection module, calculate the delay amount, generate a delay compensation signal and feed it back to the main control module to calibrate the output timing of the offset control information.

[0021] By adopting the above technical solution, the time delay compensation module can accurately calculate the delay from the acquisition of offset information to the execution of compensation by addressing the problem of calibration timing lag caused by signal transmission and execution delay in the existing system. By calibrating the control timing of the main control module through the compensation signal, it can prevent adjustment deviation caused by timing lag, ensure that the longitudinal pressure adjustment is synchronized with the printing process, and further improve the printing quality of the splicing area.

[0022] Optionally, an encoder is also included. The encoder is located at the drive shaft of the printing media transport path and is electrically connected to the signal preprocessing module. It is used to collect the transport speed signal of the printing media in real time and transmit it to the signal preprocessing module to provide a speed reference for the timing calibration of the time delay compensation module.

[0023] By adopting the above technical solution, the encoder captures the printing media delivery speed in real time, providing a dynamic speed reference for the time delay compensation module. Changes in the printing media delivery speed directly affect the relative interaction time between the print head and the media. The time delay compensation module adjusts the compensation timing based on the speed signal to prevent timing deviations caused by speed fluctuations, ensuring that longitudinal pressure adjustment and subsequent timing control can match the printing rhythm at different printing speeds, thereby improving the dynamic adaptability of the system.

[0024] Optionally, the time delay compensation module is equipped with a printing speed-timing mapping table. The time delay compensation module receives the real-time printing speed signal transmitted by the encoder, calculates the trigger time difference of the heating pulses of two adjacent printheads based on the printing speed-timing mapping table, and adjusts the heating start time of the two adjacent printheads by the trigger time difference to make the printed content in the splicing seam area aligned.

[0025] By adopting the above technical solution, the problem of stripes appearing in the splicing area due to asynchronous heating timing in the existing system is addressed. The time delay compensation module uses a preset printing speed-timing mapping table to quickly calculate the heating pulse trigger time difference of adjacent print heads at different speeds. By adjusting the heating start time, it ensures that the printed content in the splicing seam area is accurately aligned in the time dimension, eliminating image misalignment and stripes caused by asynchronous timing, and further improving the integrity and clarity of wide-format printed images.

[0026] Secondly, the printing device provided in this application adopts the following technical solution:

[0027] A printing apparatus comprising a wide-format thermal printing system as described in any one of the first aspects above.

[0028] By adopting the above technical solutions, the printing device integrates a wide-format thermal printing system with "adaptive longitudinal pressure adjustment, dynamic elimination of transverse gaps, and precise synchronization of heating timing." On the one hand, it can solve the problems of physical gaps, uneven pressure, and asynchronous timing when multiple printheads are spliced ​​in existing devices, achieving seamless, uniform, and stripe-free wide-format printed images, meeting the high-precision requirements of advertising printing, textile printing, and packaging material printing. On the other hand, the system's closed-loop adjustment mechanism can reduce local wear on the printhead, extend the printhead's lifespan, and reduce the device's maintenance and operating costs. At the same time, the adaptability design of various sensors and actuators allows the device to flexibly cope with different printing media and speed requirements.

[0029] Thirdly, this application provides a dynamic calibration method for a wide-format thermal transfer printing system, which adopts the following technical solution:

[0030] A dynamic calibration method for a wide-format thermal transfer printing system includes the following steps:

[0031] S1. Install the second detection module and calibrate its initial position. Fix the transmitter and receiver of the second detection module to the outer edge of the adjacent printheads respectively. Drive the adjacent printheads to the alignment position, record the relative position data of the second detection module and the signal parameters of the receiver, and store them as a zero offset reference. The second detection module is an optical sensor used to collect the lateral offset of the seam between adjacent printheads.

[0032] S2. Configure the closed-loop control system parameters and set the drive logic of the second compensation module. In the main control module, preset the allowable threshold for lateral offset. Configure the pulse equivalent and speed regulation parameters of the third drive motor in the second compensation module. Set the corresponding logic between the lateral offset and the motor drive amount. The second compensation module includes a third drive motor and a second guide rail. The third drive motor is used to drive the second guide rail to move the print head.

[0033] S3. Construct a timing compensation mechanism, load a time delay compensation algorithm in the preprocessing module and configure a printing speed-timing mapping table, and establish a matching benchmark between the printing media speed and the print head heating pulse timing through the encoder;

[0034] S4. Debug the first compensation module and calibrate the pressure parameters. Start the first compensation module, adjust the first guide rail to the reference height through the first drive motor, place a standard thickness medium between the print head and the pressure roller, adjust the initial position of the linear actuator, detect the pressure of the print head through the first detection module, and adjust the parameters so that the pressure deviation between the splicing seam area and the single print head is ≤5%; wherein, the first detection module is a pressure sensor, and the first compensation module includes the first drive motor, the first guide rail and the linear actuator;

[0035] S5. Perform real-time dynamic calibration. The second detection module, encoder, and first detection module respectively collect lateral offset, media delivery speed, and pressure data and feed them back to the main control module. The main control module drives the second compensation module to correct the lateral position of adjacent printheads, drives the signal preprocessing module to regulate the heating pulse timing of adjacent printheads, drives the first compensation module to adjust the longitudinal pressure of the printhead, and performs closed-loop calibration.

[0036] S6. Periodically check the calibration benchmark and update the compensation parameters. After each continuous run for a preset time or after changing the printing media, drive the print head back to the initial alignment position, compare the deviation of the current second detection module signal parameters with the zero offset benchmark, and recalibrate when the deviation exceeds the tolerance. At the same time, update the printing speed-timing mapping table parameters according to the media characteristics.

[0037] S7. Perform abnormal monitoring and adaptive closed-loop correction. When the second detection module detects that the lateral offset exceeds the threshold continuously, or the first detection module reports that the line pressure deviation continues to exceed the limit, the system automatically reduces the printing speed and triggers an alarm. It calls the backup compensation parameters to drive the first compensation module and the second compensation module to correct the deviation. After the parameters return to normal, the original speed is restored.

[0038] By adopting the above technical solution, a complete calibration system can be constructed from three dimensions: "initial benchmark calibration - real-time dynamic adjustment - media adaptation update". On the one hand, closed-loop control solves the problem of lateral offset of the splicing seam, reduces the image tortuosity caused by asynchronous heating, and eliminates the uneven printing density caused by pressure differences. On the other hand, this method does not rely on frequent manual intervention. It can establish a precise benchmark when the system starts up, respond to deviations in real time during printing (such as media tension fluctuations and slight deformation of the print head), and adapt to the characteristics of different types of media. It can effectively improve the image uniformity and splicing accuracy of wide-format thermal transfer printing, extend the service life of the print head, meet the high requirements of printing quality in advertising printing, textile printing and other scenarios, and reduce the cost and complexity of manual calibration.

[0039] In summary, this application includes at least one of the following beneficial technical effects:

[0040] 1. To address the issue of uneven pressure distribution during multi-printhead splicing in existing wide-format thermal printing systems, which leads to blurred printed images and localized wear, this solution constructs a longitudinal pressure closed-loop adjustment mechanism consisting of a first detection module and a first compensation module. The first detection module captures the longitudinal pressure values ​​of adjacent printheads in real time, providing precise pressure feedback to the main control module. The first compensation module dynamically adjusts the longitudinal position of the printheads based on the feedback pressure values. This not only specifically solves the problem of blurred printed images and localized wear caused by uneven pressure during multi-printhead splicing in existing wide-format thermal printing systems, but also overcomes the defect of the fixed pressing mechanism in traditional systems where the pressure is not adjustable. It can adapt to printing media of different thicknesses and hardnesses, ensuring that the pressure in the splicing area and the single printhead area is always adapted to the current media, preventing differences in printing density, media damage, and excessive localized wear of the printheads. This improves the uniformity of wide-format printed images, extends the service life of the printheads, and is suitable for scenarios with high printing quality requirements, such as advertising printing and textile printing.

[0041] 2. Multi-dimensional adjustment is achieved through the structure of the guide rail, drive motor and linear actuator of the pressing component. The first guide rail drives the linear actuator to move longitudinally as a whole to achieve coarse adjustment of the longitudinal position of the print head. The second drive motor drives the telescopic rod to extend and retract to achieve fine adjustment of the longitudinal position of a single print head. The linear actuator corresponds to each print head to ensure that the adjustment of each print head is independent and controllable. It can quickly respond to the feedback signal of the pressure sensor, dynamically correct pressure deviation, and reduce printing defects caused by pressure fluctuations in the splicing area.

[0042] 3. To address the issue of stripes appearing in the splicing area due to asynchronous heating timing in existing systems, the time delay compensation module uses a preset printing speed-timing mapping table to quickly calculate the heating pulse trigger time difference between adjacent printheads at different speeds. By adjusting the heating start time, it ensures that the printed content in the splicing seam area is accurately aligned in the time dimension, eliminating image misalignment and stripes caused by asynchronous timing, and further improving the integrity and clarity of wide-format printed images. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of the structure of the wide-format thermal printing system provided in the embodiments of this application;

[0044] Figure 2 This is a schematic diagram of the printing execution module and displacement calibration module of the wide-format thermal printing system provided in this application embodiment;

[0045] Figure 3 This is a schematic diagram of the printing execution module and displacement calibration module of a wide-format thermal printing system provided in another embodiment of this application;

[0046] Figure 4 This is a flowchart of a dynamic calibration method for a wide-format thermal transfer printing system provided in another embodiment of this application.

[0047] Explanation of reference numerals in the attached figures:

[0048] 10. Main control module; 20. Displacement calibration module; 21. First compensation module; 211. First guide rail; 212. First drive motor; 213. Second drive motor; 214. Linear actuator; 22. First detection module; 221. Pressure sensor; 23. Second compensation module; 231. Third drive motor; 232. Second guide rail; 24. Second detection module; 241. Optical sensor; 30. Printing execution module; 31. Print head; 40. Signal preprocessing module; 50. Encoder; 60. Printing media; 70. Pressure roller. Detailed Implementation

[0049] The following is in conjunction with the appendix Figure 1-4 This application will be described in further detail.

[0050] This application discloses a wide-format thermal printing system. (Refer to...) Figure 1In one embodiment, the wide-format thermal printing system includes a main control module 10, a displacement calibration module 20, and a printing execution module 30. The printing execution module 30 includes at least two printheads 31 connected end-to-end, with a seam formed between the adjacent printheads 31. The displacement calibration module 20 includes a first detection module 22 and a first compensation module 21. The first detection module 22 is disposed on the force transmission path of the printheads 31 and is used to collect the position offset information of the two adjacent printheads 31 and transmit it to the main control module 10. The main control module 10 outputs offset control information to the first compensation module 21 based on the position offset information. The first compensation module 21 is pressed against the surface of the printheads 31 facing away from the printing medium 60 and performs position calibration adjustment on the two adjacent printheads 31 in response to the offset control information. Wherein, the position offset information includes a longitudinal pressure value, the position calibration adjustment includes a longitudinal position adjustment, the first detection module 22 is used to detect the longitudinal pressure value of the two adjacent printheads 31, and the first compensation module 21 is used to adjust the longitudinal position of the two adjacent printheads 31 based on the longitudinal pressure value.

[0051] like Figure 1 As shown, in one embodiment, the wide-format thermal printing system includes a main control module 10, a displacement calibration module 20, a printing execution module 30, a signal preprocessing module 40, and an encoder 50. The main control module 10 employs a PLC controller. The printing execution module 30 includes at least two adjacent printheads 31, forming a printing area with the same width as the pages of the printing medium 60. A seam is formed between adjacent printheads 31. The displacement calibration module 20 includes a first compensation module 21 and a first detection module 22. The first detection module 22 is mounted on the back or side of the printhead 31 (not shown in the figure), collects the longitudinal pressure value (position offset information) of adjacent printheads 31, and transmits it to the main control module 10. Based on this, the main control module 10 outputs offset control information to the first compensation module 21, which is pressed against the surface of the printhead 31 away from the printing medium 60. The first compensation module 21 responds to adjust the longitudinal position of the adjacent printheads 31.

[0052] Understandably, by adopting the above technical solution, the problems of blurred printed images and localized wear caused by uneven pressure distribution when splicing multiple printheads 31 in existing wide-format thermal printing systems can be specifically solved. It also compensates for the core defects of traditional systems. Traditional wide-format thermal printing systems typically use a fixed pressing mechanism with non-adjustable pressure. When dealing with printing media 60 of varying thicknesses, such as advertising inkjet film as thin as 0.1mm, cotton-linen blended fabrics as thick as 5mm, and materials of varying hardness, such as soft silk with a hardness of 30 and hard packaging cardboard with a hardness of 75, either insufficient pressure results in unclear printing on thick media and poor adhesion on thin media, or excessive pressure causes deformation of soft media and wear on printheads 31 on hard media. The "longitudinal pressure closed-loop adjustment mechanism composed of the first detection module 22 and the first compensation module 21" constructed in this solution can achieve dual optimization. The first detection module 22 not only captures the longitudinal pressure values ​​of two adjacent printheads 31 in real time, but also indirectly provides feedback on the thickness and hardness characteristics of the printing media 60 (such as detecting a sudden increase in contact pressure). This often corresponds to an increase in the thickness of the printing medium 60; if the pressure distribution is uneven, it is often related to the edge area of ​​the hard printing medium 60. The main control module 10 provides precise dual feedback on pressure and medium characteristics, and the first compensation module 21 dynamically adjusts the longitudinal position of the print head 31 based on the feedback information. For example, when printing thick hard packaging cardboard, the longitudinal pressure of the printing array (multiple print heads 31) as well as the longitudinal pressure difference between two adjacent print heads 31 are increased to ensure that the ink is fully transferred. When printing thin soft silk, the longitudinal pressure is reduced to avoid damaging the fabric. Ultimately, it ensures that the pressure of the splicing area and the area of ​​a single print head 31 is always adapted to the current medium characteristics, which not only prevents the difference in printing density caused by uneven pressure, but also avoids excessive wear of the print head 31 and medium damage caused by the mismatch between the fixed pressure and the medium. This improves the uniformity of wide-format printed images and extends the service life of the print head 31. At the same time, it adapts to the printing needs of printing media 60 with different thicknesses and hardness in advertising printing, textile printing, packaging material printing and other scenarios.

[0053] Reference Figure 2 In one embodiment, the first detection module 22 is a pressure sensor 221, and each printhead 31 is provided with at least one pressure sensor 221.

[0054] Understandably, the pressure sensor 221 has high sensitivity and can accurately capture the longitudinal pressure changes of a single printhead 31, preventing pressure feedback deviation caused by shared detection elements. Each printhead 31 is equipped with at least one pressure sensor 221, which can realize independent monitoring of the pressure status of each printhead 31, ensuring that the main control module 10 can output offset control information in a targeted manner, further improving the accuracy of longitudinal position adjustment and reducing pressure interference between multiple printheads 31. Preferably, each printhead 31 is equipped with three pressure sensors 221, which are respectively positioned at the two side edges and the middle of the printhead 31 to form a multi-point detection of the longitudinal pressure of the printhead 31. These pressure sensors 221 are all located on the force transmission path of the printhead 31, such as in the direction facing the printing medium 60 or in the direction away from the printing medium 60, to collect the longitudinal pressure value of the printhead 31 in contact with the printing medium 60 in real time. In particular, by observing the pressure distribution difference between the edges and the middle, the pressure balance of the printhead 31 is accurately reflected, providing multi-dimensional data support for the main control module 10 to determine the positional deviation and output adjustment commands. In other embodiments, the number of pressure sensors 221 can be flexibly adjusted according to the size of the printhead 31 and the requirements of detection accuracy.

[0055] Reference Figure 2 In one embodiment, the first compensation module 21 includes a pressing assembly, which includes a first guide rail 211, a first drive motor 212, a second drive motor 213, and at least two linear actuators 214. Each linear actuator 214 is correspondingly positioned to a print head 31. The body of each linear actuator 214 is fixed to the first guide rail 211, and the end of the telescopic rod of the linear actuator 214 presses against the surface of the print head 31 facing away from the printing medium 60. The first drive motor 212 drives the first guide rail 211 to move in a direction perpendicular to the surface of the printing medium 60, and the second drive motor 213 drives the telescopic rod to extend and retract. A pressure roller 70 is located below the printing execution module 30. The printing medium 60 is located between the print head 31 and the pressure roller 70. During printing, the print head 31 is responsible for printing patterns or text onto the printing medium 60 via thermal transfer, while the pressure roller 70 pushes the printing medium 60 forward continuously, allowing the printing process to continue.

[0056] It is understood that the pressing assembly constitutes a floating pressing mechanism, the structure of which includes a first guide rail 211, a first drive motor 212, a second drive motor 213, and at least two linear actuators 214. The linear actuators 214 correspond one-to-one with the printheads 31, and their bodies are fixed on the first guide rail 211. The ends of the telescopic rods are pressed against the surface of the printheads 31 facing away from the medium. This structural design enables the graded adjustment of the longitudinal position of the printheads 31. The first drive motor 212 drives the first guide rail 211 to move as a whole in a direction perpendicular to the surface of the medium (vertical direction) through a transmission component (not shown in the figure), completing the coarse adjustment of the longitudinal position of the printheads 31. The second drive motor 213 drives the telescopic rods to extend and retract independently, realizing the fine adjustment of the pressure and longitudinal position of a single printhead 31, laying the structural foundation for precise control of pressure deviation.

[0057] In one embodiment, the pressure sensor 221 is a strain gauge, positioned in the direction facing the medium (i.e., the side where the print head 31 contacts the printing medium 60), directly sensing the pressing force of the print head 31 on the medium. In another embodiment, it can also be positioned on other pressure transmission paths, such as the contact point between the extension rod of the linear actuator 214 and the print head 31 (indirectly reflecting the pressure borne by the medium by detecting the thrust of the extension rod on the print head 31), or at the bearing seat of the pressure roller 70 (inferring the pressure distribution of the printing area by monitoring the reaction force on the pressure roller 70). When the splicing area passes through the pressure roller 70, these strain gauges (pressure sensors 221) transmit the real-time collected pressure signals to the main control module 10, which adjusts the drive parameters associated with the linear actuator 214 through a PID control algorithm (a closed-loop control method that calculates and dynamically corrects pressure deviations using proportional, integral, and derivative functions). Since the pressure consistency between the splicing area and the single-head area directly determines the printing density and pattern uniformity, the line pressure deviation between the splicing area and the single-head area can be strictly controlled within the range of ≤5% through real-time correction of PID control, preventing color depth breaks or pattern blurring at the splicing point due to pressure differences.

[0058] In one embodiment, the linear actuator 214 includes an electric push rod, a voice coil motor, a piezoelectric ceramic actuator, or a pneumatic or hydraulic cylinder with servo control.

[0059] Understandably, offering a variety of linear actuator 214 types can adapt to different printing scenario requirements. For example, nitrogen spring cylinders (pneumatic cylinders) have stable spring force output and are suitable for textile printing scenarios with high pressure stability requirements; hydraulic spring cylinders (hydraulic cylinders) have high adjustment precision and are suitable for high-precision printing requirements such as advertising printing. One type or multiple different types of linear actuators 214 can be used simultaneously in a printing system, taking into account both practicality and scenario compatibility.

[0060] Reference Figure 1 and Figure 3In one embodiment, the displacement calibration module 20 not only has longitudinal pressure adjustment capability, but also constructs a closed-loop adjustment mechanism for lateral offset through the second detection module 24 and the second compensation module 23. The displacement calibration module 20 also includes a second detection module 24 and a second compensation module 23. The second detection module 24 is located on the bodies of two adjacent printheads 31 and near the seam, used to collect the lateral offset at the seam and transmit it to the main control module 10. The second compensation module 23 includes a third drive motor 231 and a second guide rail 232. The main control module 10 receives the lateral offset and controls the third drive motor 231 to drive the second guide rail 232 to move along the width direction of the printing medium 60, thereby moving the printheads 31 to adjust the gap of the seam. Preferably, in one embodiment, the second detection... Module 24 consists of a set of optical sensors 241, corresponding to one seam. It consists of two sensors (transmitter and receiver), which are fixed on the outer edges of two adjacent printheads 31. For example, when printheads 31 (printhead A) and 31 (printhead B) form a seam, the transmitter optical sensor 241 is installed on the side of printhead 31 (printhead A) near the seam, and the receiver optical sensor 241 is installed on the side of printhead 31 (printhead B) near the seam. The two are completely aligned without any offset, with only an initial tiny seam (e.g., within 0.02mm) between them. The second detection module 24 is located on the bodies of two adjacent printheads 31 and near the seam. It is used to collect the lateral offset at the seam and transmit it to the main control module 10. The specific detection process includes three core steps: First, the initialization phase. Before the system starts, the two printheads 31 are made to be in a completely aligned and offset-free state. At this time, the stable detection signal (such as infrared light or laser) emitted by the transmitter is accurately aligned with the receiver to form a signal path. The main control module 10 records the relative position data (such as the lateral standard distance) of the two at this time and the signal strength / position coordinates of the receiver as the zero offset reference; Second, the printing process... During the process, the alignment data is refreshed every 50ms. If the print head 31 is laterally offset (such as print head A moving to the left, causing the splice seam to widen, or moving to the right, causing it to overlap with B), it will change the relative position of the transmitter and receiver, causing the signal received by the receiver to become weaker or stronger, or the position coordinates to shift (such as shifting to the left by 0.03mm or to the right by 0.04mm). Thirdly, the offset is calculated. The main control module 10 compares the signal data transmitted by the receiver in real time with the zero offset reference to obtain the specific offset value (such as the current coordinate shifting to the right by 0.008mm from the reference, which means that print head A has shifted to the right by 0.008mm relative to print head B).The second compensation module 23 includes a third drive motor 231 and a second guide rail 232. After receiving the lateral offset, the main control module 10 controls the third drive motor 231 to drive the second guide rail 232 to move along the width direction of the printing medium 60 (e.g., when the offset is 0.008mm, the print head A is driven to move to the left by 0.008mm), thereby driving the print head 31 to move synchronously to adjust the gap of the splicing seam and eliminate the physical gap problem caused by the offset.

[0061] Understandably, this design, combined with the lateral adjustment of the displacement calibration module 20, compensates for the shortcomings of traditional fixed pressing mechanisms, such as non-adjustable pressure and lack of dynamic offset correction. It adapts to printing media 60 of different thicknesses (e.g., advertising inkjet film as thin as 0.1mm, cotton-linen blended fabrics as thick as 5mm) and different hardnesses (e.g., soft silk with a hardness of 30, hard packaging cardboard with a hardness of 75), reducing the damage caused by differences in printing density, media damage, and excessive wear of the print head 31. On the other hand, the lateral closed-loop adjustment formed by the second detection and second compensation modules 23 can achieve single-time precise calibration of the splicing seam during system installation and debugging, ensuring no initial gaps. It can also dynamically correct the offset caused by media tension fluctuations and print head 31 deformation in real time during the printing process. This effectively overcomes the shortcomings of existing static splicing that cannot adapt to dynamic printing displacement, achieving seamless splicing of wide-format thermal transfer printing images throughout the entire process. Ultimately, it improves the uniformity of wide-format printed images, extends the life of the print head 31, and meets the continuous splicing accuracy requirements of advertising printing, textile printing, and other scenarios with high printing quality requirements.

[0062] It should be noted that in this embodiment, the drive motor (first drive motor 212, third drive motor 231) can be a stepper motor, and it can be connected to the guide rail (first guide rail 211, second guide rail 232) through a transmission component. The transmission component includes a precision ball screw with a lead of 0.5mm, which can convert the rotational motion of the drive motor into linear motion, thereby achieving high-precision displacement adjustment of the load (such as the print head 31) on the guide rail.

[0063] In one embodiment, the second detection module 24 includes an optical sensor 241, a laser displacement sensor, a visual image sensor, or a grating ruler displacement sensor.

[0064] Understandably, various types of sensors can meet different accuracy and scenario requirements: optical sensors 241 and laser displacement sensors have fast response speeds, and in high-speed printing scenarios (such as large-format advertising inkjet printing, where printing speeds can reach tens of centimeters per second or even faster), they can quickly capture and feedback minute offsets in the seams, ensuring that the printed images can still be accurately spliced ​​at high speeds; visual image sensors can directly capture image information of the seams. For example, in the field of packaging printing, when printing rigid packaging cardboard with complex patterns, the main control module 10 can intuitively judge the offset status through the image and correct it in time to ensure the integrity of the packaging pattern splicing and prevent pattern misalignment from affecting the packaging aesthetics and quality; grating ruler displacement sensors have extremely high accuracy. In high-end printing scenarios such as silk digital heat transfer printing, where splicing accuracy requirements are stringent, such as producing high-precision silk scarf heat transfer patterns, even micron-level offsets can cause pattern defects. They can accurately detect and correct offsets, ensuring perfect pattern presentation, and further broaden the application range of the printing system of this application in printing scenarios with different accuracy requirements.

[0065] It should be noted that, in one embodiment, the newly added second detection module 24 and the second compensation module 23 construct a lateral offset closed-loop adjustment mechanism. The second compensation module 23 and the first compensation module 21 are stacked to achieve independent movement of the X-axis and Z-axis. This can meet the single-time accurate detection and calibration requirements during the system installation and debugging phase. For example, when installing advertising printing equipment, the staff starts the second detection module 24 (such as optical sensor 241 with a resolution of 0.01mm) to align with the seam of adjacent printheads 31, collects the initial lateral offset in one go and transmits it to the main control module 10. The main control module 10 controls the third drive motor 231 of the second compensation module 23 to drive the second guide rail 232, causing the printhead 31 to move along the width direction of the printing medium 60 until the seam gap is reduced to the allowable range of the process (such as ≤0.02mm), ensuring that there is no physical gap in the initial splicing state of the equipment to lay the foundation for subsequent printing. In another embodiment, it can also be adapted to In real-time dynamic adjustment scenarios during the printing process, such as heat transfer printing on textile fabrics, fluctuations in the tension of the printing medium 60 (such as cotton and linen fabrics) and slight deformation of the print head 31 after prolonged operation may cause lateral displacement of the splicing seam. At this time, the second detection module 24 (such as a laser displacement sensor) will continuously monitor the lateral displacement of the splicing seam, capture the minute displacement of the print head 31 at the ±0.01mm level in real time, and feed it back to the main control module 10. The main control module 10 quickly controls the third drive motor 231 to drive the second guide rail 232 to drive the print head 31 to correct its position along the width direction, dynamically eliminating the gap of the splicing seam to prevent misalignment of patterns such as flowers and stripes on the fabric. This mechanism effectively solves the defects of existing static splicing (positioning only during installation and not adjustable during printing) that cannot adapt to dynamic printing displacement, ensuring that wide-format heat transfer printed images can achieve "seamless" splicing throughout the entire process, meeting the continuous demand for splicing accuracy in advertising printing, textile printing and other scenarios.

[0066] Reference Figure 1 In one embodiment, the system further includes a signal preprocessing module 40, which is electrically connected between the main control module 10 and the displacement calibration module 20. The signal preprocessing module 40 includes a time delay compensation module (not shown in the figure). The time delay compensation module is used to receive the position offset information of the first detection module 22, calculate the transmission and execution delay, generate a delay compensation signal, and feed it back to the main control module 10 to calibrate the output timing of the offset control information.

[0067] Understandably, the wide-format thermal printing system also includes a signal preprocessing module 40, which is electrically connected between the main control module 10 and the displacement calibration module 20. One component of this module is a time delay compensation module implemented based on an FPGA chip. Leveraging its parallel computing capabilities, the FPGA can receive position offset information (such as the longitudinal pressure value and lateral offset of adjacent printheads 31) collected by the first detection module 22 in real time, and complete the calculation of the entire link delay within nanoseconds. This includes the circuit delay of signal transmission from the pressure sensor 221 and optical sensor 241, the computational delay of command generation by the main control module 10, and the mechanical action delay of the first compensation module 21 (such as the linear actuator 214 and drive motor). Simultaneously, the timing logic unit built into the FPGA can dynamically store delay parameter models under different operating conditions, quickly generate delay compensation signals based on real-time data, and feed them back to the main control module 10. This accurately calibrates the output timing of the offset control information, ensuring complete synchronization between the control commands and the real-time position of the printing medium 60 and the dynamic state of the printhead 31.

[0068] By adopting the above technical solution, the calibration timing lag problem caused by signal transmission and execution delays in existing systems (for example, the serial calculation of traditional processors is difficult to keep up with the media movement speed during high-speed printing, resulting in the adjustment action lagging behind the actual offset) is addressed. The FPGA-based time delay compensation module, with its hardware-level parallel computing capabilities, can control the timing deviation of the entire link within microseconds. This design not only prevents "adjustment mismatch" caused by timing lag (such as local pressure overload caused by the asynchronous pressure compensation action and media position), but also ensures that the longitudinal pressure adjustment and the dynamic response of the printing process are perfectly matched. Regardless of the media moving at any speed from 0-500mm / s, the FPGA can correct the control timing in real time, so that the pressure calibration action of the print head 31 is accurately applied to the current printing area, and the pressure at the seam is always kept balanced and stable. This further improves the printing clarity and uniformity of the splicing area, providing hardware-level timing assurance for high-speed, high-precision wide-format printing.

[0069] Reference Figure 1In one embodiment, an encoder 50 is also included. The encoder 50 is located at the drive shaft of the printing medium 60 conveying path and is electrically connected to the signal preprocessing module 40. It is used to collect the conveying speed signal of the printing medium 60 in real time and transmit it to the signal preprocessing module 40 to provide a speed reference for the timing calibration of the time delay compensation module.

[0070] Understandably, encoder 50, as a real-time monitoring unit for the motion state of printing medium 60, can acquire the instantaneous conveying speed of the medium (such as dynamic changes within the range of 0-500 mm / s) in real time through mechanical linkage with the drive shaft of the conveying path of printing medium 60, and transmit this speed signal to signal preprocessing module 40 in the form of high-frequency pulses. For the time delay compensation module based on FPGA, this speed signal becomes the core benchmark for timing calibration. When the medium speed increases, the relative interaction time between print head 31 and printing medium 60 is shortened, and FPGA can synchronously compress the response window of compensation timing according to the speed signal; when the speed decreases, the timing adjustment cycle is extended accordingly, so that the calculation model of delay compensation always keeps dynamically adapted to the medium motion state.

[0071] By adopting the above technical solution, the encoder 50 captures the conveying speed of the printing medium 60 in real time, providing a dynamic speed reference for the time delay compensation module. Changes in the conveying speed of the printing medium 60 directly affect the relative interaction time between the print head 31 and the medium. The time delay compensation module adjusts the compensation timing based on the speed signal to prevent timing deviations caused by speed fluctuations, ensuring that longitudinal pressure regulation and subsequent timing control can match the printing rhythm at different printing speeds, thus improving the dynamic adaptability of the system. Especially in wide-format printing, even small fluctuations in the medium speed (such as the instantaneous deceleration of textile fabric due to tension changes, or speed fluctuations during high-speed conveying of advertising inkjet film) can cause the print head 31 to deviate from its action timing. The synergistic effect of the encoder 50 and the FPGA can control this dynamic deviation at the microsecond level, enabling pressure regulation, timing compensation, and medium movement to form a closed-loop synchronization, further ensuring the splicing printing accuracy under high-speed variable working conditions.

[0072] It should be noted that, in one embodiment, the speed of encoder 50 is related to the lateral detection sampling frequency. When the medium speed collected by encoder 50 is ≥200mm / s, the lateral detection sampling frequency is increased to 20Hz (once every 50ms); when the speed is <200mm / s, the sampling frequency is set to 10Hz (once every 100ms) to ensure the real-time performance of lateral calibration during high-speed printing.

[0073] It should be noted that, in one embodiment, the wide-width thermal printing system can form a "multi-dimensional collaborative adjustment" scheme, which combines the longitudinal position adjustment of the displacement calibration module 20 (accurately corrects the longitudinal pressure deviation of the print head 31 through the first detection module 22 and the first compensation module 21 to adapt to the pressing requirements of media with different thicknesses and hardnesses), the lateral adjustment (relying on the second detection module 24 and the second compensation module 23 to dynamically correct the lateral offset of the splicing seam and prevent pattern misalignment), and the timing calibration of the signal preprocessing module 40 (based on the FPGA time delay compensation module) and the encoder 50 (calibrating the timing of control commands based on the media delivery speed to match the printing rhythm). This entire adjustment mechanism forms a closed-loop linkage, which can not only make up for the defects of the optical sensor 241 of the traditional fixed pressing mechanism, such as "unadjustable pressure, no offset correction, and no timing adaptation", but also achieve customized adaptation for printing media 60 with different characteristics. It can effectively reduce the difference in printing density (such as uneven depth of splicing area), reduce media damage (such as indentation of soft fabric and tearing of hard paper) and excessive wear of print head 31 (such as shortened life of print head 31 due to local pressure overload), significantly improve the overall uniformity of wide-format printed images, extend the service life of print head 31, and adapt to scenarios with high printing quality requirements such as advertising printing (requiring large-format high-definition seamless) and textile printing (requiring adaptation to various fabrics and fine patterns).

[0074] In another embodiment, based on practical application needs and cost control, the system can also flexibly choose to enable only one or several adjustment methods. For example, in a simple wide-format sign printing scenario with low requirements for splicing accuracy, only the longitudinal position adjustment of the displacement calibration module 20 can be retained. The cooperation of the pressure sensor 221 and the linear actuator 214 ensures that the basic pressure of the print head 31 and the medium is properly matched, reducing equipment costs while meeting basic printing quality. In a high-speed advertising inkjet printing scenario, the timing calibration of the signal preprocessing module 40 and the encoder 50 can be enabled, combined with the lateral adjustment function, to ensure timing synchronization under high-speed printing and prevent misalignment of splicing seam patterns, balancing printing efficiency and accuracy. In high-end scenarios such as silk digital heat transfer printing, full-dimensional adjustment of longitudinal, lateral and timing can be enabled to achieve micron-level precision control through multi-module collaboration, meeting the printing quality requirements of high-end fabrics.

[0075] In one embodiment, the time delay compensation module is provided with a printing speed-timing mapping table. The time delay compensation module receives the real-time printing speed signal transmitted by the encoder 50, calculates the trigger time difference of the heating pulses of two adjacent printheads 31 based on the printing speed-timing mapping table, and adjusts the heating start time of the two adjacent printheads 31 by the trigger time difference, so that the printed content in the splicing seam area is aligned.

[0076] Print speed-timing mapping table

[0077] Understandably, the pre-stored printing speed-timing mapping table in the time delay compensation module is a model of the correspondence between speed and trigger time difference established based on a large amount of experimental data. The table covers matching parameters between different printing speeds (such as 50mm / s to 500mm / s) and the trigger time difference of heating pulses of adjacent printheads 31. When the encoder 50 transmits the real-time acquired media conveying speed signal to the time delay compensation module, the module can directly call the optimal trigger time difference parameter for the corresponding speed from the mapping table (without complex real-time calculation) to quickly determine the start interval of the heating pulses of adjacent printheads 31: for example, when printing at low speed (e.g., 100mm / s), the trigger time difference is extended to 1000μs to match the slow movement rhythm of medium-thick media such as canvas, ensuring sufficient heat transfer; when printing at high speed (e.g., 400mm / s), the trigger time difference is shortened to 250μs to adapt to the rapid movement of ultra-thin media such as thin PET film. Through compact timing control, the pattern in the splicing area is prevented from being stretched or misaligned, and the heating action of the front and rear printheads 31 is accurately matched with the media position in the time dimension.

[0078] By adopting the above technical solution, the problem of stripes appearing in the splicing area due to asynchronous heating timing in existing systems is addressed. The time delay compensation module uses a preset printing speed-timing mapping table to quickly calculate the heating pulse trigger time difference of adjacent printheads 31 at different speeds. By adjusting the heating start time, it ensures that the printed content in the splicing seam area is accurately aligned in the time dimension, eliminating image misalignment and stripes caused by asynchronous timing, and further improving the integrity and clarity of wide-format printed images. Especially when printing gradient patterns or continuous lines, this timing calibration can prevent color gradation breaks or line shifts at the splicing point, ensuring a consistent visual effect from the edge to the center of the wide-format image, meeting the high requirements for visual continuity in advertising images, textile patterns, and other applications.

[0079] It should be noted that the timing calibration of the time delay compensation module is applied synchronously to the longitudinal pressure regulation (linear actuator 214 action delay compensation) and the lateral offset regulation (motor drive delay compensation), ensuring that the adjustment actions of both are matched with the medium conveying speed, and preventing splicing deviations caused by asynchronous adjustment of multiple modules.

[0080] Reference Figure 4 In this application embodiment, a dynamic calibration method for a wide-format thermal transfer printing system is also disclosed, including:

[0081] S1: Install the second detection module 24 and calibrate its initial position. Fix the transmitter and receiver of the second detection module 24 to the outer edge of the adjacent printhead 31 respectively. Drive the adjacent printhead 31 to the fully aligned position. Record the relative position data of the second detection module 24 and the signal parameters of the receiver and store them as a zero offset reference. The second detection module 24 is an optical sensor 241, which is used to collect the lateral offset of the seam between the adjacent printheads 31.

[0082] Understandably, the optical sensors 241 are installed and their initial positions are calibrated. The transmitting and receiving ends of one set of optical sensors 241 are fixed to the outer edges of adjacent printheads 31, ensuring that they are perfectly aligned with an initial small seam gap in a no-offset state. Before system startup, the printheads 31 are driven to the fully aligned position, and the relative position data of the optical sensors 241 and the receiving end signal parameters are recorded and stored as a zero-offset reference. The relative position data serves as the "reference coordinates" for the lateral offset, used to quantify the degree of offset detected subsequently. For example, in the zero-offset state, the lateral distance between printheads 31 (printhead A) and 31 (printhead B) is recorded as 0.01mm. If the distance is subsequently detected to change to 0.03mm, the lateral offset can be directly calculated as 0.02mm, providing precise numerical basis for the main control module 10 to output drive signals (such as controlling the second compensation module 23 to move the corresponding distance). The receiving end signal parameters serve as the "reference threshold" for the optical signals, used to determine whether the printheads 31 are in an aligned state. The signal strength (such as luminous flux and voltage value) at the receiving end of the optical sensor 241 is directly related to the alignment between the transmitter and receiver. The signal parameters (such as voltage 3.5V) are at their strongest when there is zero offset. If the signal parameters subsequently drop to 2.8V (below the preset threshold), it can be quickly determined that the print head 31 has shifted laterally, triggering the calibration mechanism. Qualitative detection of offset can be achieved without relying on position data, thus improving the response speed.

[0083] S2: Configure the closed-loop control system parameters and set the drive logic of the second compensation module 23. Preset the allowable threshold for lateral offset in the main control module 10, configure the pulse equivalent and speed regulation parameters of the third drive motor 231 in the second compensation module 23, and set the corresponding logic of "lateral offset amount and motor drive amount"; wherein, the second compensation module 23 includes the third drive motor 231 and the second guide rail 232, and the third drive motor 231 is used to drive the second guide rail 232 to move the print head 31;

[0084] Understandably, closed-loop control system parameters refer to a series of core control parameters that ensure the system can achieve precise and stable compensation and adjustment based on the detected lateral offset. These parameters mainly include detection end parameters, control end parameters, execution end parameters, and compensation logic related parameters. The closed-loop control system parameters are configured, the stepper motor drive logic is set, and the allowable threshold for lateral offset (e.g., ≤0.01mm) is preset in the main control module 10. The pulse equivalent and speed adjustment parameters of the third drive motor 231 (stepper motor) of the second compensation module 23 are configured. The corresponding logic of "offset - drive amount" is set, that is, the offset value detected by the optical sensor 241 and the distance moved by the stepper motor to the print head 31 form a 1:1 compensation relationship to ensure that the adjustment accuracy matches the detection accuracy.

[0085] S3: Construct a timing compensation mechanism, load a time delay compensation algorithm in the preprocessing module and configure a printing speed-timing mapping table, and establish a matching benchmark between the media speed and the heating pulse timing of the print head 31 through the encoder 50;

[0086] Understandably, the time delay compensation algorithm is loaded into the FPGA chip, a printing speed-timing mapping table is set, and the time delay compensation algorithm is embedded in the FPGA chip. The corresponding parameters of different printing speeds (such as 50-500mm / s) and the trigger time difference of heating pulses of adjacent printheads 31 are entered into the mapping table. The media delivery speed signal is collected by encoder 50 to verify the algorithm's response time to calling the mapping table and ensure that the timing calibration delay is ≤10 microseconds.

[0087] S4: Debug the first compensation module 21 and calibrate the pressure parameters. Start the first compensation module 21, adjust the first guide rail 211 to the reference height through the first drive motor 212, place a standard thickness medium between the print head 31 and the pressure roller 70, adjust the initial position of the linear actuator 214, detect the pressure of the print head 31 through the first detection module 22, and adjust the parameters so that the pressure deviation between the corresponding area of ​​the splicing seam and the single print head 31 is ≤5%; wherein, the first detection module 22 is a pressure sensor 221, and the first compensation module 21 includes a pressing component, a first drive motor 212 and a linear actuator 214;

[0088] Understandably, in one embodiment, the linear actuator 214 can employ an actuation structure with elastic buffering function, such as a nitrogen spring assembly, to adjust the pressing component. Simultaneously, the linear actuator is equipped with a damper (e.g., a silicone oil-filled structure) to suppress high-frequency vibrations during printing and ensure the stability of pressure detection. At this time, the second drive motor 213 adjusts the extension and contraction (i.e., compression stroke) of the nitrogen spring through mechanical transmission, utilizing the mechanical properties of the nitrogen spring to achieve precise control of the printhead pressure. Specifically, the pressing component of the first compensation module 21 is activated, and the first drive motor... 212. Adjust the first guide rail 211 to the reference height; place a standard thickness medium (such as 0.5mm PVC film) between the print head 31 and the pressure roller 70, and adjust the output pressure of the linear actuator 214 (e.g., adjust the initial position of the nitrogen spring) to the range of 5-15N, so that the linear pressure of the single-head area detected by the strain gauge (pressure sensor 221) reaches the preset value (e.g., 10N / m); test the pressure distribution of the splicing area, and adjust the parameters by using a damper with a silicone oil-filled structure (viscosity coefficient of 200cSt) to effectively suppress pressure fluctuations and ensure that the deviation of the linear pressure between the splicing area and the single-head area is ≤5%. For example, in a preferred embodiment, a 0.5mm thick PVC standard medium is placed between the print head 31 and the pressure roller 70, the initial position of the linear actuator 214 is adjusted to 10N / m, the pressure of the splicing area is detected by the pressure sensor 221 as 9.8N / m, the pressure of the single print head 31 area is 10.2N / m, and the pressure deviation is 4%, which meets the process requirement of ≤5%.

[0089] S5: Perform real-time dynamic calibration. The second detection module 24, encoder 50 and first detection module 22 respectively collect lateral offset, media delivery speed and pressure data and feed them back to the main control module 10. The main control module 10 drives the second compensation module 23 to correct the lateral position of the adjacent printhead 31, drives the signal preprocessing module 40 to adjust the heating pulse timing of the adjacent printhead 31, drives the first compensation module 21 to adjust the longitudinal pressure of the printhead 31, and performs closed-loop calibration.

[0090] Understandably, the system starts and executes real-time closed-loop monitoring and adjustment. The second detection module 24, encoder 50, and first detection module 22 respectively collect data on lateral offset, media delivery speed, and printhead 31 pressure, which are synchronously transmitted to the main control module 10 and the FPGA chip. The main control module 10 drives the third drive motor 231 to correct the lateral position of the printhead 31 based on the lateral offset. It uses a PID control algorithm to control the step size of the second drive motor 213, thereby fine-tuning the compression of the nitrogen spring to correct the longitudinal pressure deviation. The FPGA chip uses a mapping table based on the media delivery speed to regulate the heating pulse timing, forming a detection-feedback-adjustment closed loop. In one embodiment, the system starts and refreshes the detection data of the optical sensor 241 every 50ms. The main control module 10 drives the stepper motor to dynamically correct the lateral position based on the offset. The FPGA chip uses a mapping table based on the real-time speed signal of the encoder 50 to regulate the trigger time difference of the heating pulses of adjacent printheads 31. Strain gauges continuously collect pressure data, and the main control module 10 dynamically adjusts the pressure of the nitrogen spring using a PID algorithm to maintain pressure balance.

[0091] In one embodiment, the method further includes step S6: periodically verifying the calibration benchmark and updating the compensation parameters. After each continuous operation for a preset duration or after changing the printing medium 60, the print head 31 is driven back to the initial alignment position. The deviation between the current signal parameters of the second detection module 24 and the zero offset benchmark is compared. If the deviation exceeds the tolerance, the calibration is recalibrated. At the same time, the printing speed-timing mapping table parameters are updated according to the media characteristics.

[0092] Understandably, after every 8 hours of continuous operation or after changing the type of printing media 60, a benchmark check is performed, driving the print head 31 back to its initial alignment position, comparing the deviation of the current sensor signal parameters with the zero offset benchmark, and recalibrating if the deviation exceeds 0.005mm; and updating the supplementary parameters of the printing speed-timing mapping table according to the media characteristics (such as thickness and hardness) to ensure compensation accuracy under different media.

[0093] In one embodiment, the system further includes step S7: performing anomaly monitoring and adaptive closed-loop correction. When the second detection module 24 detects that the lateral offset exceeds the threshold continuously, or the first detection module 22 reports that the line pressure deviation continues to exceed the limit, the system automatically reduces the printing speed and triggers an alarm, calls the backup compensation parameters to drive the first compensation module 21 and the second compensation module 23 to correct the deviation, and restores the original speed after the parameters return to normal.

[0094] Understandably, when the optical sensor 241 detects that the lateral offset exceeds the allowable threshold three times in a row, or the strain gauge feedback pressure deviation is continuously greater than 5%, the system automatically reduces the printing speed to 30% (no less than 50 mm / s) and triggers an audible and visual alarm. The main control module 10 calls the backup compensation parameters (such as enhancing the nitrogen spring pressure adjustment amplitude) to try to correct the deviation in the reduced speed state. After the parameters return to the normal range, the original speed is gradually restored.

[0095] Through the above dynamic calibration method, a complete calibration system can be constructed from three dimensions: "initial benchmark calibration - real-time dynamic adjustment - media adaptation update". On the one hand, the closed-loop control of the optical sensor 241 and the stepper motor solves the problem of lateral offset of the splicing seam, the timing calibration of the FPGA and encoder 50 reduces the image tortuosity caused by asynchronous heating, and the pressure adjustment of the floating pressing mechanism eliminates the uneven printing density caused by pressure difference. On the other hand, this method does not rely on frequent manual intervention. It can establish a precise benchmark when the system starts up, respond to deviations in real time during the printing process (such as media tension fluctuations and slight deformation of the print head 31), and adapt to the characteristics of different types of media. Ultimately, it effectively improves the image uniformity and splicing accuracy of wide-format thermal transfer printing, extends the service life of the print head 31, meets the high requirements for printing quality in advertising printing, textile printing and other scenarios, and reduces the cost and complexity of manual calibration.

[0096] This application also discloses a printing apparatus, which includes the wide-format thermal printing system in any of the above embodiments.

[0097] By adopting the above technical solutions, the printing device integrates a wide-format thermal printing system with "adaptive longitudinal pressure adjustment, dynamic elimination of transverse gaps, and precise synchronization of heating timing." On the one hand, it can solve the problems of physical gaps, uneven pressure, and asynchronous timing when multiple printheads 31 are spliced ​​in existing devices, achieving seamless, uniform, and stripe-free wide-format printed images, meeting the high-precision requirements of advertising printing, textile printing, and packaging material printing. On the other hand, the closed-loop adjustment mechanism of the system can reduce local wear of the printhead 31, extend the life of the printhead 31, and reduce the maintenance and operating costs of the device. At the same time, the adaptability design of various sensors and actuators allows the device to flexibly cope with different printing media 60 and speed requirements.

[0098] The above are all preferred embodiments of this application and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A wide-format thermal printing system, characterized in that, include: The system comprises a main control module (10), a displacement calibration module (20), and a printing execution module (30). The printing execution module (30) includes at least two printheads (31) connected end-to-end, with a seam formed between adjacent printheads (31). The displacement calibration module (20) includes a first detection module (22) and a first compensation module (21). The first detection module (22) is positioned on the force transmission path of the printheads (31) and is used to collect position offset information of the two adjacent printheads (31) and transmit it to the main control module (10). The main control module (10) outputs offset control information to the first compensation module (21) based on the position offset information. The first compensation module (21) is pressed against the surface of the printheads (31) facing away from the printing medium (60) and adjusts the position of the two adjacent printheads (31) in response to the offset control information. The position offset information includes a longitudinal pressure value. The position calibration adjustment... The system includes longitudinal position adjustment. The first detection module (22) is used to detect the longitudinal pressure value of two adjacent printheads (31). The first compensation module (21) is used to adjust the longitudinal position of the two adjacent printheads (31) based on the longitudinal pressure value. The displacement calibration module (20) also includes a second detection module (24) and a second compensation module (23). The second detection module (24) is set on the body of the two adjacent printheads (31) and close to the seam. It is used to collect the lateral offset at the seam and transmit it to the main control module (10). The second compensation module (23) includes a third drive motor (231) and a second guide rail (232). The main control module (10) receives the lateral offset and controls the third drive motor (231) to drive the second guide rail (232) to move along the width direction of the printing medium (60), thereby moving the printheads (31) to adjust the gap of the seam.

2. The wide-format thermal printing system according to claim 1, characterized in that, The first detection module (22) is a pressure sensor (221), and each printhead (31) is provided with at least one pressure sensor (221).

3. The wide-format thermal printing system according to claim 1, characterized in that, The first compensation module (21) includes a pressing assembly, which includes a first guide rail (211), a first drive motor (212), a second drive motor (213), and at least two linear actuators (214). The linear actuators (214) are arranged one-to-one with the print head (31). The body of the linear actuator (214) is fixed to the first guide rail (211). The end of the telescopic rod of the linear actuator (214) is pressed against the surface of the print head (31) away from the printing medium (60). The first drive motor (212) is used to drive the first guide rail (211) to move in a direction perpendicular to the surface of the printing medium (60). The second drive motor (213) is used to drive the telescopic rod of the linear actuator (214) to extend and retract.

4. The wide-format thermal printing system according to claim 1, characterized in that, The second detection module (24) includes an optical sensor (241), a laser displacement sensor, a visual image sensor, or a grating ruler displacement sensor.

5. The wide-format thermal printing system according to claim 1, characterized in that, It also includes a signal preprocessing module (40), which is electrically connected between the main control module (10) and the displacement calibration module (20). The signal preprocessing module (40) includes a time delay compensation module, which is used to receive the position offset information of the first detection module (22), calculate the delay amount, generate a delay compensation signal and feed it back to the main control module (10) to calibrate the output timing of the offset control information.

6. The wide-format thermal printing system according to claim 5, characterized in that, It also includes an encoder (50), which is located at the drive shaft of the printing medium (60) transport path and is electrically connected to the signal preprocessing module (40) for collecting the transport speed signal of the printing medium (60) and transmitting it to the signal preprocessing module (40) to provide a speed reference for the timing calibration of the time delay compensation module.

7. The wide-format thermal printing system according to claim 6, characterized in that, The time delay compensation module is equipped with a printing speed-timing mapping table. The time delay compensation module receives the printing speed signal transmitted by the encoder (50), calculates the trigger time difference of the heating pulses of two adjacent print heads (31) based on the printing speed-timing mapping table, and adjusts the heating start time of the two adjacent print heads (31) by the trigger time difference, so that the printing content of the corresponding area of ​​the splicing seam is aligned.

8. A printing apparatus, characterized in that, Includes the wide-format thermal printing system as described in any one of claims 1-7.

9. A dynamic calibration method for a wide-format thermal transfer printing system, applied to the wide-format thermal printing system as described in any one of claims 1-7, characterized in that, Including the following steps: S1. Install the second detection module (24) and calibrate the initial position. Fix the transmitter and receiver of the second detection module (24) to the outer edge of the adjacent print head (31) respectively. Drive the adjacent print head (31) to the alignment position. Record the relative position data of the second detection module (24) and the signal parameters of the receiver and store them as a zero offset reference. The second detection module (24) is an optical sensor (241) used to collect the lateral offset of the splice seam of the adjacent print head (31). S2. Configure the closed-loop control system parameters, set the drive logic of the second compensation module (23), preset the allowable threshold for lateral offset in the main control module (10), configure the pulse equivalent and speed regulation parameters of the third drive motor (231) in the second compensation module (23), and set the corresponding logic between the lateral offset and the motor drive amount; wherein, the second compensation module (23) includes the third drive motor (231) and the second guide rail (232), and the third drive motor (231) is used to drive the second guide rail (232) to move the print head (31); S3. Construct a timing compensation mechanism, load the time delay compensation algorithm in the preprocessing module and configure the printing speed-timing mapping table, and establish a matching benchmark between the speed of the printing medium (60) and the heating pulse timing of the print head (31) through the encoder (50); S4. Debug the first compensation module (21) and calibrate the pressure parameters. Start the first compensation module (21), adjust the first guide rail (211) to the reference height through the first drive motor (212), place a standard thickness medium between the print head (31) and the pressure roller (70), adjust the initial position of the linear actuator (214), detect the pressure of the print head (31) through the first detection module (22), and adjust the parameters so that the pressure deviation between the area corresponding to the splice seam and the single print head (31) is ≤5%; wherein, the first detection module (22) is a pressure sensor (221), and the first compensation module (21) includes the first drive motor (212), the first guide rail (211) and the linear actuator (214). S5. Perform real-time dynamic calibration. The second detection module (24), the encoder (50) and the first detection module (22) respectively collect the lateral offset, media delivery speed and pressure data and feed them back to the main control module (10). The main control module (10) drives the second compensation module (23) to correct the lateral position of the adjacent printhead (31), drives the signal preprocessing module (40) to regulate the heating pulse timing of the adjacent printhead (31), drives the first compensation module (21) to adjust the longitudinal pressure of the printhead (31), and performs closed-loop calibration.

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