Annular height measurement and control device, method and system for ink-jet printer

Abstract

The invention discloses an annular height measurement and control device, method and system for an ink-jet printer. The device comprises induction double rings, a capacitance collector, a signal receiver, a main control unit and a servo driving device, the induction double rings are installed around a code spraying head, induction capacitance is formed by the induction double rings and a workpiece to be sprayed, and height information in the 360-degree range around a spraying head is reflected through capacitance value changes. The capacitance collector collects, shapes and amplifies capacitance signals based on a CLC parallel resonance circuit, the signal receiver extracts frequency information, then the main control unit calculates the current height of a spray head, the servo driving device is controlled by combining a preset target value to conduct real-time height adjustment on a code spraying head, and a closed-loop control process is formed. The system supports induction distance calibration, man-machine interaction setting and a PLC communication protocol, has the characteristics of non-contact distance measurement, omnibearing induction, high precision, strong adaptability and the like, and is suitable for various industrial code spraying scenes with uneven workpiece surfaces and variable sizes.

Description

Technical Field

[0001] The present invention belongs to the technical field of inkjet printer equipment, and in particular relates to a ring height measurement and control device, method and system for an inkjet printer. Background Art

[0002] In modern manufacturing, inkjet coding technology serves as a crucial tool for product identification, information labeling, quality tracking, and production process management. It is widely used in a variety of fields, including metalworking, machinery manufacturing, building materials processing, warehousing and logistics, food and beverage, and electronic information. In particular, in the processing and distribution of large or irregularly shaped workpieces, such as steel plates, profiles, and pipes, inkjet coding equipment is often tasked with marking information such as batch numbers, origins, production dates, and specifications to meet multiple requirements, including product traceability, process control, and quality assurance. To ensure legible and secure printed characters, while also ensuring they adhere effectively to the workpiece and do not interfere with subsequent processing, controlling the distance between the printhead and the surface being marked is crucial. Ideally, the printhead distance from the workpiece surface should always be maintained within a precise and stable range to achieve the optimal balance between code clarity, line width control, and ink droplet adhesion. If the printhead distance is too close, it can scratch the workpiece surface, causing equipment damage, or cause ink splashing due to excessive jet pressure. If the distance is too far, characters can become blurred, lines can break, or ink droplets can appear incomplete, seriously impacting code quality. Therefore, how to achieve automatic adjustment of the print head height in different coding environments, different shapes of workpieces, and dynamic movement processes has become an important technical issue in this field.

[0003] Traditional methods for controlling printhead height rely primarily on structural constraints or point measurement. A common approach involves using a dedicated fixture or tooling to mechanically secure the printhead at a specific height, indirectly controlling the printhead's coding distance through contact between the tooling and the workpiece being printed. While simple in structure, this approach relies heavily on the standard size and fixed shape of the workpiece. When encountering workpieces with varying sizes or significant surface variations, frequent tooling changes or re-commissioning are necessary, resulting in cumbersome operation and limited versatility. This makes it unsuitable for high-frequency, multi-category batch coding operations.

[0004] To achieve more intelligent height control, a laser ranging module has been introduced. This uses a point laser sensor to measure the height of a single point on the coding path in real time, and combines it with a motor to control the position of the printhead for dynamic adjustment. However, this technology also has significant limitations: on the one hand, laser ranging can generally only sense the height information of a certain side or angle of the printhead, and it is difficult to fully reflect the distance status in different directions around the printhead. On the other hand, because the printhead moves dynamically along the path, the data measured by the sensor has a certain lag and cannot fully and synchronously reflect the height changes of the printhead's real-time position. This is especially prone to height control errors under high-speed coding conditions.

[0005] In addition, to improve ranging accuracy and coverage, some technologies attempt to use visual recognition or laser scanning to pre-scan and model the workpiece surface, establish a complete three-dimensional height distribution map, and then have the control system dynamically adjust the height of the printhead based on the path information. Although such solutions can theoretically achieve high control accuracy, they generally have problems such as long modeling time, high system costs, and poor real-time performance. Especially in scenarios where continuous processing and rapid switching of workpiece types are required, a pre-scan operation must be performed on each workpiece before coding, which significantly increases the preparation time for each product, resulting in a decrease in the efficiency of the entire line, making it difficult to adapt to the needs of modern industrial applications with fast production cycles, diverse product varieties, and high efficiency requirements.

[0006] Overall, existing inkjet printer height control technologies suffer from poor adaptability, significant control delays, high structural rigidity, and low intelligence when faced with complex working conditions and highly variable workpiece surface features. These issues make it difficult to meet the higher demands for automation and quality stability in inkjet printing, as demanded by smart manufacturing and flexible production lines. In particular, when high-precision inkjet printing is required on complex surfaces with uneven surfaces, significant height fluctuations, variable shapes, or edges prone to collision, a new nozzle height sensing and control device and method with more responsiveness, more flexible structure, more comprehensive measurement, and greater adaptability is urgently needed to achieve highly intelligent, controllable, and high-quality output in the inkjet printing process. Summary of the Invention

[0007] To solve the above technical problems, the present invention provides a ring height measurement and control device, method and system for inkjet printers. The specific technical solution is as follows: A ring-shaped height measurement and control device for an inkjet printer includes an inductive double-ring structure installed on the inkjet printer. The inductive double-ring structure forms an inductive capacitance with the workpiece to be sprayed, and the height information of the inkjet printer is obtained by the inductive capacitance value; the inductive double-ring structure includes an inductive outer ring and an inductive inner ring that are insulated from each other. The inductive inner ring is used to obtain the inductive capacitance reflecting the height information of the inkjet printer nozzle, and the inductive outer ring is used to obtain the inductive capacitance reflecting the peripheral height information of the inkjet printer nozzle; the inductive outer ring and the inductive inner ring are both provided with an output connector for outputting the inductive capacitance information.

[0008] Furthermore, a position adjustment component is provided between the induction outer ring and the induction inner ring, and the position adjustment component includes a sliding hinge, a telescopic rod and a fixed hinge; one end of the sliding hinge is provided in a sliding groove opened along the circumference of the inner wall of the induction outer ring, or is slidably mounted on a sliding rail provided along the circumference of the inner wall of the induction outer ring, and the other end of the sliding hinge is connected to the telescopic rod; the end of the telescopic rod away from the sliding hinge is connected to the induction inner ring through a fixed hinge; at least one of the sliding hinge, telescopic rod and fixed hinge is an insulator.

[0009] Furthermore, the induction outer ring is formed by bending a metal strip, and the two ends of the metal strip are connected to each other through a sleeve ring, and the sleeve ring is provided with a locking screw, which is used to cooperate with the positioning holes opened on the metal strip to lock the two ends of the metal strip; after the locking screw is removed, the two ends of the metal strip slide relative to each other along the metal strip through the sleeve ring to adjust the size of the induction outer ring.

[0010] Preferably, the induction double-ring structure is further provided with an adhesive member for fixed connection with the inkjet printer, and the adhesive member is a strong magnetic sheet or adhesive sticker.

[0011] A method for measuring and controlling the height of an inkjet printer comprises the following steps: Install the above-mentioned ring height measurement and control device on the inkjet printer; Connecting the annular height measurement and control device to a signal processing circuit via an output connector to obtain a square wave signal containing induced capacitance information; Performing filtering and smoothing processing on the square wave signal to obtain a frequency value of the square wave signal; Calibrate the inkjet printer nozzle height and the square wave signal frequency value; The frequency value of the square wave signal is obtained in real time, and the corresponding actual value of the inkjet printer nozzle height is obtained according to the calibration relationship, and is input into the inkjet printer servo control system.

[0012] Furthermore, the signal processing circuit includes a capacitive signal acquisition circuit and a filtering and comparison circuit; the capacitive signal acquisition circuit includes a CLC parallel resonant circuit, a signal holding circuit and a shaping and enhancement circuit connected in sequence, the CLC parallel resonant circuit is used to connect to the output connector of the annular height measurement and control device, and the shaping and enhancement circuit is used to amplify and enhance the output signal of the signal holding circuit; the filtering and comparison circuit is used to perform frequency screening on the output signal of the shaping and enhancement circuit, and convert the screened signal into a square wave signal through an operational amplifier comparator.

[0013] Furthermore, when calibrating the height of the inkjet printer and the frequency value of the square wave signal, the actual height of the inkjet printer nozzle is continuously adjusted from low to high or from high to low through the inkjet printer servo control system, and the corresponding square wave signal frequency value is obtained to establish a one-to-one correspondence between the height of the inkjet printer nozzle and the frequency value of the square wave signal; for the corresponding relationship not obtained during calibration, it is determined by the difference method.

[0014] A printer height measurement and control system based on the above method includes an annular height measurement and control device installed on the printer, a signal processing circuit connected to the annular height measurement and control device, and a core processing module connected to the signal processing circuit. The core processing module is used to obtain the frequency value of the square wave signal output by the signal processing circuit, and output the actual value of the printer nozzle height to the printer servo control system based on the calibration relationship between the square wave signal frequency value and the actual value of the printer nozzle height; the printer servo control system adjusts the printer nozzle height according to the deviation between the actual value of the nozzle height and the set value.

[0015] Furthermore, it also includes a calibration module, which is used to continuously adjust the actual height of the inkjet printer nozzle from low to high or from high to low through the inkjet printer servo control system, and obtain the corresponding square wave signal frequency value, and record the one-to-one correspondence between the inkjet printer nozzle height and the square wave signal frequency value; for the corresponding relationship not obtained during calibration, it is determined by the difference method.

[0016] Furthermore, it also includes a human-computer interaction module and an alarm prompt module; the human-computer interaction module is used to set system parameters and trigger operation control instructions through a touch screen or input and output device; the alarm prompt module is used to output an alarm signal when the actual height of the inkjet printer nozzle deviates from the set range.

[0017] Compared to traditional solutions that rely on single-point distance measurement with a point laser rangefinder, this invention achieves 360° height sensing capability around the inkjet printer terminal through a ring-shaped capacitive sensing structure, effectively avoiding information distortion caused by limited installation location, single distance measurement direction, and measurement lag. The adopted inductive capacitor structure is not restricted by installation angle and direction, and can provide real-time, high-precision height feedback signals during printhead movement. This allows the printhead to maintain a stable and appropriate printing distance throughout the entire coding path, significantly improving coding quality and process stability.

[0018] In addition, compared with the existing pre-scanning pattern building control method, the present invention greatly improves the inkjet printing efficiency while ensuring control accuracy. The traditional modeling method requires a complete surface scan and mathematical modeling before each inkjet printing. Although it can achieve a high degree of restoration of the surface contour, the overall inkjet printing efficiency is significantly reduced due to the time-consuming modeling and complex data processing, which has a serious impact on the production rhythm, especially in mass production scenarios. The present invention only needs to calibrate the sensing distance of the same type of workpiece once, and then the parameters can be directly called in the subsequent inkjet printing process without repeating the scanning and modeling operations, realizing a continuous and efficient follow-up inkjet printing process, which greatly reduces the inkjet printing preparation time and system response delay.

[0019] The present invention also embodies excellent structural adaptability and convenience of system integration. The inductive double-ring structure is made of red copper, which has excellent conductivity and strong plasticity. The surface is sprayed with polyester resin material, which has good insulation, rust resistance and corrosion resistance, so that it can adapt to complex and changeable industrial use environments. The modular structural design and magnetic installation method of the device enable it to be quickly integrated into various types of inkjet printing equipment without the need for major modifications to the original structure, effectively reducing deployment costs. At the same time, the system is equipped with a complete capacitance acquisition circuit, signal receiving and shaping amplification circuit, combined with a closed-loop control system composed of FPGA and core processor, which realizes high-precision and high-robustness dynamic control while ensuring a high degree of real-time adjustment capability.

[0020] In terms of human-computer interaction, the present invention has also been optimized. Parameter setting, sensing distance calibration and inching control are performed through the touch screen interface, making user operation simple and intuitive. At the same time, it also realizes compatible communication with PLC and other automation systems based on a simple IO handshake protocol. It can be embedded as an independent module in various intelligent inkjet coding production lines, with strong scalability and low development cost.

[0021] In summary, the present invention not only improves control accuracy, response speed and system flexibility, but also takes into account process adaptability, deployment convenience and automation integration requirements, providing an efficient, reliable and industrial application-oriented comprehensive solution to solve the problems of directional limitations, low efficiency and poor versatility in the existing technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. They are used to explain the present invention together with the embodiments of the present invention and do not constitute a limitation of the present invention.

[0023] Figure 1 This is a schematic diagram of the induction double-loop structure provided by one embodiment of the present invention; Figure 2 This is a capacitance signal acquisition circuit diagram provided by an embodiment of the present invention; Figure 3 This is a physical diagram of a signal acquisition module provided by an embodiment of the present invention; Figure 4 This is a filter comparison circuit diagram provided by an embodiment of the present invention.

[0024] Wherein, each reference numeral represents: 1-Induction outer ring, 2-Mounting part, 3-Adhesive part, 4-Outer ring locking screw, 5-Sliding hinge, 6-Telescopic rod, 7-Insulating hinge, 8-Telescopic rod locking screw, 9-Mounting part screw, 10-Cable, 11-Inner ring connector, 12-Outer ring connector. DETAILED DESCRIPTION

[0025] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, other embodiments obtained by ordinary technicians in this field without making creative efforts are all within the scope of protection of the present invention.

[0026] A ring height measurement and control device for a printer, such as Figure 1 As shown, the device comprises a dual-ring induction structure consisting of an outer induction ring 1 and an inner induction ring. The outer induction ring 1 is constructed from a highly malleable copper strip, bent from a single copper strip. The two ends of the strip are connected by a sleeve ring. The sleeve ring is equipped with an outer ring locking screw 4, which engages with positioning holes in the copper strip to lock the ends. After removing the outer ring locking screw 4, the ends of the copper strip can slide relative to each other along the copper strip via the sleeve ring, allowing the size of the outer induction ring 1 to be adjusted.

[0027] In order to facilitate cooperation with the inkjet printer, a plurality of adhesive parts 3 are installed on the induction outer ring 1 through the mounting part 2. The adhesive parts 3 are made of strong magnetic sheets or strong adhesive stickers, which can be magnetically attracted or adhered to the surface of the inkjet printer.

[0028] The inductive inner ring is arranged on the inner side of the inductive outer ring 1 through multiple position adjustment components. The position adjustment components include a sliding hinge 5, a telescopic rod 6, and an insulating hinge 7. One end of the sliding hinge 5 is slidably arranged in a slide groove or on a slide rail provided on the inner wall of the inductive outer ring 1, and can slide circumferentially along the inner wall of the inductive outer ring 1; the other end of the sliding hinge 5 is connected to the telescopic rod 6, and the end of the telescopic rod 6 away from the sliding hinge 5 is connected to the inductive inner ring through the insulating hinge 7. The telescopic rod 6 includes multiple sleeves that are sleeved layer by layer to achieve telescopic adjustment. It is also equipped with a telescopic rod locking screw 8 for locking the telescopic rod after adjusting the length of the telescopic rod. The insulating hinge 7 is used to block the electrical connection between the inductive outer ring 1 and the inductive inner ring. In fact, in order to prevent the inductive outer ring 1 and the inductive inner ring from being electrically connected, it is only necessary to block the conductivity of the position adjustment component connecting the inner and outer rings. That is, at least one of the sliding hinge 5, the telescopic rod 6, and the insulating hinge 7 is an insulator.

[0029] A flexible cable 10 is connected to the inductive inner ring, and one end of the cable 10 is provided with an inner ring connector 11 for deriving the inner ring capacitance sensing signal. The cable 10 is wrapped with insulating material to prevent short circuit. Similarly, an outer ring connector 12 for deriving the outer ring capacitance sensing signal is also provided on the inductive outer ring 1. In some embodiments, to facilitate wiring or wiring, the inner ring connector 11 can also be installed on the inductive outer ring 1 simultaneously, but it is important to maintain insulation from the inductive outer ring 1. Specifically, the inner ring connector 11 and the outer ring connector 12 use SMA interfaces for connecting to the input node GC_INP of the capacitance signal collector via a high-frequency coaxial cable.

[0030] The dual-ring sensor structure is installed at the bottom of the printer. The thin sensor rings allow the printhead to be closer to the workpiece, thus supporting a wide range of adjustable heights. The inner ring accurately senses the printhead's range, while the outer ring, after adjustment to approximate the printer's external dimensions, is used for edge detection and overall collision avoidance. The sensor structure, which fuses the inner and outer rings' sensor data, supports lateral distance detection to the printhead.

[0031] The main body of the induction double ring is made of red copper, which has better conductivity than existing materials such as stainless steel on the market, can make the height feedback more sensitive, and greatly improve the stability of equipment operation. At the same time, red copper has excellent plasticity, which can reduce the difficulty of processing. In actual application, the tail handle can be manually bent and cut in any direction according to the size and installation space of different inkjet printers, which greatly improves the installation efficiency and reduces the difficulty of reprocessing due to different inkjet printer sizes and structures. It can be applied to various installation environments. The surface of the induction double ring is sprayed with polyester resin material. Compared with the pure metal rings currently on the market, the surface wear resistance, rust resistance, and ink corrosion resistance are greatly improved. It can effectively eliminate the wear and dirt problems caused by attachments such as dust and ink during use, facilitate daily cleaning and maintenance, and extend the service life of the induction double ring.

[0032] The dual induction rings are attached to the printer via magnetic or adhesive mounting hardware. The number of mounting hardware is optional. Compared to existing systems that rely solely on clamping at the end of the handle, this system offers more installation options, a smaller footprint, and superior anti-shake and anti-drift capabilities. This effectively reduces high-speed sensing noise and alarm shutdowns caused by the dual induction rings shifting during high-speed operation, significantly improving production efficiency. The mounting magnets are encased in nylon and electrically isolated from the dual induction rings, preventing interference with the sensing effect. The mounting hardware utilizes a snap-fit ​​installation method, ensuring the dual induction rings can be quickly disassembled for maintenance. Its strong wear resistance, oil resistance, and excellent dimensional stability effectively extend the life of the fixture.

[0033] By installing the annular height measuring device on the inkjet printer and connecting it to the signal processing circuit via the output interface, the induced capacitance signal reflecting the height of the printer nozzle can be obtained. In this embodiment, the signal processing circuit includes a capacitance signal acquisition circuit and a filter comparison circuit.

[0034] like Figure 2 As shown, the capacitance signal acquisition circuit includes three parts connected in sequence: a CLC parallel resonant circuit, a signal holding circuit, and a shaping enhancement circuit. Figure 3 This is a physical picture of the capacitance signal acquisition circuit. The SMA interface is on the right, connected to the induction loop through a high-frequency coaxial cable, and the power supply and output signal terminal are on the left.

[0035] (1) The inner core of the inductive dual-ring SMA interface is electrically connected to the GC_INP of the CLC parallel resonant circuit, and the grounding point PE of the equipment housing is electrically connected to GC_INN. The inductive capacitance value is usually in the range of 50-200pF, and forms a CLC resonant cavity structure with C24, C25, and L2. The transistor MMBT3904 is repeatedly charged and discharged to achieve a steady-state oscillation state. R18 and R19 divide the voltage to form the base static operating voltage. R21 is electrically connected to the emitter and PE to provide temperature negative feedback current to ensure the temperature stability of the circuit. C23 provides a very small AC impedance path based on the static operating point, providing a low-impedance flow path for the oscillating current.

[0036] (2) The signal holding circuit obtains the AC signal as input from the connection between C24 and L2 through C26. C27 and R23 are connected in parallel to the base of the second transistor MMBT3904. R22, R23, and R24 work together to provide a stable static operating point, keeping the circuit output impedance low and the input impedance high, playing the role of signal following.

[0037] (3) The shaping and enhancement circuit is the third stage of the acquisition circuit. It is a signal amplifier based on an operational amplifier. It can increase the signal amplitude and overcome the signal attenuation during long-distance transmission. The reverse input terminal of the operational amplifier is electrically connected to R25 and R26, and the positive input terminal is connected to the PE terminal through R27. The signal amplification factor is determined by the ratio of R25 and R26. The final stable AC signal is output to the GC_OUT port. Note that the positive and negative voltages of the input power rail of the operational amplifier should be equal in magnitude and opposite in sign. This ensures that the signal is not deformed within the power rail range, thereby ensuring that the receiving end can accurately extract the frequency information.

[0038] Figure 4This is a filter and comparator circuit, whose input AS_IN is connected to the output GC_OUT of the capacitor signal acquisition circuit via a coaxial cable. R132 and C183 form a pre-lowpass filter circuit, while R133 and C184, connected in series, form a damped highpass circuit. Together, these two components form a frequency selection circuit capable of reliably extracting 0.5-3MHz signals. The signal passes through a subsequent op amp comparator, converting the AC signal, which has a smooth zero-crossing, into a square wave with sharp edges, which is output to the AS_OUT port.

[0039] The input pin of the FPGA (core processing module) is electrically connected to the AS_OUT port of the filter and comparator circuit, receiving and processing the square wave signal containing capacitance information. The FPGA oversamples the square wave signal at a 250MHz clock frequency, measures the duration of each high-level pulse, and filters it using a median filter with a width of 10 and a sliding average filter with a width of 200 within a 1ms control cycle to obtain a smoothed period value. This is then converted into a frequency value. After computational processing, the resulting position information serves as the feedback signal input for the inkjet printer's highly closed-loop control system.

[0040] The execution process of the inkjet printer's highly closed-loop control system is as follows: (1) Read the frequency value converted from the capacitor acquisition signal at a sampling frequency of 1kHz (consistent with the control cycle) ; (2) According to the sensing distance calibration Scattered point relationship, interpolation calculation to obtain the original distance value ; (3) According to the electrical environment interference, the user sets the filter strength parameter, based on which the observation noise covariance matrix of the distance Kalman filter is set, and the filtered distance value is calculated. ; (4) According to the nozzle height target value set by the user , in each control cycle, calculate the nozzle height error of the current cycle ; (5) In each control cycle, an adaptive proportional-integral controller is applied , adaptively adjust the proportional control gain and the integration time constant The adaptive control law is: when the error is small, a low proportional gain and a small integral time constant are used; when the error is large, a high proportional gain and a large integral time constant are used; (6) Calculate the servo speed control value ; (7) The current servo control amount and the previous period value Compare to prevent the single cycle acceleration from exceeding the set allowable value , thereby reducing mechanical vibration and ensuring coding quality.

[0041] The speed control quantity with limited acceleration is:

[0042] in For the control cycle.

[0043] (8) It is input as a speed command to the servo driver to control the height movement of the nozzle.

[0044] (9) According to The control cycle executes (1) to (8) cyclically.

[0045] The above control system also includes human-computer interaction functions, which include parameter setting, sensing distance calibration, motor jogging, etc.

[0046] Parameter setting: Using the touch screen and interface design, you can quickly set parameters such as follow-up stiffness, filter strength, servo speed gain, and number of feedback pulses per revolution.

[0047] Sensing distance calibration: Click the "Sensing distance calibration" touch button on the screen, and the device will execute the "Sensing distance calibration process": (1) Send a speed command of 30 rpm to the servo driver to control the induction ring and the nozzle to slowly descend.

[0048] (2) Detect the change of capacitance during the descent process. The closer the induction ring is to the workpiece to be sprayed, the greater the capacitance is. Detect the capacitance-distance derivative value. .

[0049] (3) When When the capacitance value is greater than the preset threshold or becomes 0, the touch signal is triggered.

[0050] (4) Send a speed command of 0 rpm to the driver, the motor stops rotating, and the gun head stops descending.

[0051] (5) Delay for 2 seconds to wait for the workpiece and the induction ring to stabilize and no longer vibrate slightly.

[0052] (6) Send a speed command of -10 rpm to the driver, the induction ring and the nozzle rise slowly, and the command duration is 10 seconds.

[0053] (7) During the rising process, the capacitance data and encoder feedback position are collected in each sampling cycle, one by one corresponding to each other and stored in the device memory.

[0054] (8) After the rising collection is completed, the position closed-loop control is executed, and the rotating motor makes the induction double ring and the nozzle return to the initial position.

[0055] (9) The touch screen displays "Sensor distance calibration completed" and indicates whether it is successful. If successful, the follow-up coding is allowed; if failed, the follow-up coding is not allowed. Common causes of failure are electrical interference and unstable installation of the induction double ring.

[0056] Motor Jog: Used to manually adjust the printhead height. Clicking the "Forward" or "Reverse" buttons on the interface sends a constant speed command of 20rpm or -20rpm to the servo driver, controlling the motor to rotate forward or reverse at a constant speed, thereby controlling the up and down movement of the induction ring and the printhead.

[0057] This embodiment defines a simple IO handshake protocol based on two IO ports and one output port for alarm shutdown, enabling both servo printing and alarm output. This requires minimal software development, making it ideal for integration into automation equipment such as PLCs as a standalone module. The two IO ports serve as the input for the servo start signal and the output for the servo in-position signal. This device communicates with the host system (e.g., PLC) through these two ports to implement the handshake protocol and inkjet printing according to the following process.

[0058] (1) Before starting the follow-up coding, make sure that the sensing distance calibration has been performed and is successful.

[0059] (2) The user sets the parameters such as the follow-up inkjet printing height and filtering intensity.

[0060] (3) The upper system sends a follow-up start signal to this device, which is read by the core processor chip.

[0061] (4) This equipment executes the control process of the closed-loop control system, moving the nozzle and the induction double ring to a position within ±0.1mm of the specified height, and the instantaneous speed converted from the encoder feedback is less than 5rpm.

[0062] (5) This device outputs a follow-up position signal, which is received by the upper system.

[0063] (6) The upper system controls the inkjet printer and other linkage mechanisms to execute the inkjet printing actions of the upper system.

[0064] (7) After the font or pattern is sprayed, the upper system outputs an invalid signal (high level is invalid) for the start of follow-up to this device, which is read by the core processor chip.

[0065] (8) The upper system performs closed-loop control based on the encoder feedback, moving the nozzle and the induction double loop back to the initial position at the beginning of the follow-up.

[0066] In the above process, if the height is sensed to be too low or too high (deviating from the preset target value by 3mm), the device will trigger an alarm signal output, which will be received by the upper system and execute a series of safety shutdown actions required by the upper system.

[0067] The above is the main content of this embodiment. Based on the principle of capacitive sensing, this embodiment designs a ring-shaped height measurement and control device based on an inductive double-ring structure that can sense a 360° range on all sides, is easy to install, and has strong versatility. It should be noted that the inductive double-ring structure is not limited to a perfect circle. Any structure with a closed outer contour should be within the protection range, such as a rectangle, an ellipse, a triangle, etc. This embodiment designs a dedicated capacitance collector for the electrical structure of the inductive double ring, which includes a CLC parallel resonant circuit, a holding circuit, a shaping circuit, a filtering circuit, and a comparison circuit. This embodiment also designs a set of action processes based on two IO ports that can simply communicate with a PLC to realize follow-up coding. The programming is simple and it is easy to embed it as an independent module into complex automation equipment.

[0068] Unlike laser rangefinders, this method uses capacitive sensing to measure printhead height. While also a non-contact measurement method, this method offers a wider sensing range, unrestricted installation locations, and a more versatile installation method.

[0069] Through the description of the above embodiments, those skilled in the art will clearly understand that each embodiment can be implemented using software plus a general hardware platform, or of course, hardware. Based on this understanding, the essence of the above technical solution, or the portion that contributes to the relevant technology, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium (such as ROM / RAM, a magnetic disk, an optical disk, etc.), and includes a number of instructions for executing the methods described in the above embodiments or certain portions of the embodiments.

[0070] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Under the idea of ​​the present invention, the technical features in the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of different aspects of the present invention as described above. For the sake of simplicity, they are not provided in detail. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in this field should understand that they can still modify the technical solutions described in the above embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of this application.

Claims

1. A ring height measurement and control device for a printer, characterized in that: It includes an inductive double-ring structure installed on the inkjet printer, which forms an inductive capacitor with the workpiece to be sprayed, and obtains the height information of the inkjet printer through the inductive capacitance value; the inductive double-ring structure includes an inductive outer ring and an inductive inner ring that are insulated from each other, the inductive inner ring is used to obtain the inductive capacitor reflecting the height information of the inkjet printer nozzle, and the inductive outer ring is used to obtain the inductive capacitor reflecting the peripheral height information of the inkjet printer nozzle; the inductive outer ring and the inductive inner ring are both provided with an output connector for outputting the inductive capacitance information.

2. The annular height measurement and control device according to claim 1, characterized in that: A position adjustment component is provided between the induction outer ring and the induction inner ring, and the position adjustment component includes a sliding hinge, a telescopic rod and a fixed hinge; one end of the sliding hinge is provided in a sliding groove opened along the circumference of the inner wall of the induction outer ring, or is slidably mounted on a sliding rail provided along the circumference of the inner wall of the induction outer ring, and the other end of the sliding hinge is connected to the telescopic rod; the end of the telescopic rod away from the sliding hinge is connected to the induction inner ring through a fixed hinge; at least one of the sliding hinge, telescopic rod and fixed hinge is an insulator.

3. The annular height measurement and control device according to claim 1, characterized in that: The induction outer ring is formed by bending a metal strip, and the two ends of the metal strip are connected to each other through a sleeve ring, and a locking screw is provided on the sleeve ring. The locking screw is used to cooperate with the positioning holes opened on the metal strip to lock the two ends of the metal strip; after the locking screw is removed, the two ends of the metal strip slide relative to each other along the metal strip through the sleeve ring to adjust the size of the induction outer ring.

4. The annular height measurement and control device according to claim 1, characterized in that: The induction double-ring structure is further provided with an adhesive member for fixed connection with the inkjet printer, and the adhesive member is a strong magnetic sheet or adhesive sticker.

5. A method for measuring and controlling the height of a printer, characterized in that: Including steps: Installing the annular height measurement and control device according to any one of claims 1 to 4 on an inkjet printer; Connecting the annular height measurement and control device to a signal processing circuit via an output connector to obtain a square wave signal containing induced capacitance information; Performing filtering and smoothing processing on the square wave signal to obtain a frequency value of the square wave signal; Calibrate the inkjet printer nozzle height and the square wave signal frequency value; The frequency value of the square wave signal is obtained in real time, and the corresponding actual value of the inkjet printer nozzle height is obtained according to the calibration relationship, and is input into the inkjet printer servo control system.

6. The inkjet printer height measurement and control method according to claim 5, wherein: The signal processing circuit includes a capacitance signal acquisition circuit and a filtering and comparing circuit; the capacitance signal acquisition circuit includes a CLC parallel resonant circuit, a signal holding circuit and a shaping and enhancing circuit connected in sequence, the CLC parallel resonant circuit is used to connect to the output connector of the annular height measurement and control device, and the shaping and enhancing circuit is used to amplify and enhance the output signal of the signal holding circuit; the filtering and comparing circuit is used to perform frequency screening on the output signal of the shaping and enhancing circuit, and convert the screened signal into a square wave signal through an operational amplifier comparator.

7. The inkjet printer height measurement and control method according to claim 5, wherein: When calibrating the height of the inkjet printer and the frequency value of the square wave signal, the actual height of the inkjet printer nozzle is continuously adjusted from low to high or from high to low through the inkjet printer servo control system, and the corresponding square wave signal frequency value is obtained to establish a one-to-one correspondence between the height of the inkjet printer nozzle and the frequency value of the square wave signal; for the corresponding relationship not obtained during calibration, it is determined by the difference method.

8. A height measurement and control system for a printer based on the method of claim 5, characterized in that: It includes an annular height measurement and control device installed on the inkjet printer, a signal processing circuit connected to the annular height measurement and control device, and a core processing module connected to the signal processing circuit. The core processing module is used to obtain the frequency value of the square wave signal output by the signal processing circuit, and output the actual value of the inkjet printer nozzle height to the inkjet printer servo control system based on the calibration relationship between the square wave signal frequency value and the actual value of the inkjet printer nozzle height; the inkjet printer servo control system adjusts the inkjet printer nozzle height according to the deviation between the actual value of the nozzle height and the set value.

9. The inkjet printer height measurement and control system as claimed in claim 8, characterized in that: It also includes a calibration module, which is used to continuously adjust the actual height of the inkjet printer nozzle from low to high or from high to low through the inkjet printer servo control system, and obtain the corresponding square wave signal frequency value, and record the one-to-one correspondence between the inkjet printer nozzle height and the square wave signal frequency value; for the corresponding relationship not obtained during calibration, it is determined by the difference method.

10. The inkjet printer height measurement and control system as claimed in claim 8, characterized in that: It also includes a human-computer interaction module and an alarm prompt module; the human-computer interaction module is used to set system parameters and trigger operation control instructions through a touch screen or input and output devices; the alarm prompt module is used to output an alarm signal when the actual height of the inkjet printer nozzle deviates from the set range.

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