An annular height measuring and controlling device, method and system for a code jet

Abstract

The application discloses a kind of annular height measurement and control device, method and system for code jet instrument.The device includes inductive double ring, capacitance collector, signal receiver, main control unit and servo drive device, the inductive double ring is installed around the code jet head, and forms inductive capacitance with the workpiece to be sprayed, and the height information of 360 ° range around the code jet head is reflected by the change of capacitance value.The capacitance collector collects, shapes and amplifies the capacitance signal based on CLC parallel resonance circuit, the signal receiver extracts frequency information, and the main control unit calculates the current height of the code jet head, and combines the preset target value to control the servo drive device to adjust the height of the code jet head in real time, to form a closed-loop control process.The system supports inductive distance calibration, man-machine interactive setting and PLC communication protocol, has the characteristics of non-contact distance measurement, omnidirectional induction, high precision and strong adaptability, and is suitable for various industrial code jet scenes with uneven workpiece surface and variable size.

Description

Technical Field

[0001] This invention belongs to the field of inkjet printing equipment technology, and particularly relates to a ring height measurement and control device, method and system for inkjet printers. Background Technology

[0002] In modern manufacturing, inkjet printing technology serves as a crucial tool for product identification, information labeling, quality tracking, and production process management, and is widely applied in various fields such as metal processing, machinery manufacturing, building materials processing, warehousing and logistics, food and beverage, and electronic information. Especially in the processing and transfer of large-sized or irregularly shaped workpieces such as steel plates, profiles, and pipes, inkjet printing equipment typically undertakes the task of marking information such as product batch numbers, origin, production time, and specifications to meet multiple needs including product traceability, process control, and quality supervision. To ensure that the printed characters are clear, legible, and firmly adhered without affecting subsequent workpiece processing, controlling the distance between the printhead and the marked surface is particularly critical. Ideally, the printhead distance should always be maintained within a precise and stable range to achieve the optimal balance between printhead clarity, line width control, and ink droplet adhesion. If the printhead is too close, it may scrape against the workpiece surface, causing equipment damage, or excessive ink pressure may cause ink splattering; if the distance is too far, it will result in blurred characters, broken lines, or incomplete printing, severely affecting the quality of the inkjet printing. Therefore, how to automatically adjust the nozzle height in different coding environments, for workpieces of different shapes, and during dynamic movement has become an important technical issue in this field.

[0003] Traditional methods for controlling printhead height primarily rely on structural constraints or point-to-point measurements. A common approach involves using specialized fixtures or tooling to fix the printing machine at a certain height, indirectly controlling the printing distance of the printhead through the contact between the tooling and the workpiece. While this method is structurally simple, it is highly dependent on the standard dimensions and fixed shape of the workpiece. When encountering workpieces with varying sizes or significant surface irregularities, frequent tooling changes or readjustments are necessary, making the operation cumbersome, lacking versatility, and unsuitable for high-frequency, multi-category batch printing operations.

[0004] To achieve more intelligent height control, some solutions have introduced laser ranging modules. These modules use point laser sensors to measure the height of a single point on the coding path in real time, and combine this with motor-controlled nozzle position adjustment. However, this technology also has significant limitations: firstly, laser ranging can generally only sense the height information of a certain side or angle of the nozzle, making it difficult to comprehensively reflect the distance status in different directions around the nozzle; secondly, because the nozzle moves dynamically along the path, the data measured by the sensor has a certain lag, and cannot fully and synchronously reflect the real-time height changes of the nozzle's position, especially under high-speed coding conditions, which can easily cause height control errors.

[0005] Furthermore, to improve ranging accuracy and coverage, some technologies attempt to pre-scan and model the workpiece surface using visual recognition or laser scanning to establish a complete three-dimensional height distribution map. The control system then dynamically adjusts the nozzle height based on the path information. While these solutions can theoretically achieve high control accuracy, they generally suffer from long modeling times, high system costs, and poor real-time performance. Especially in scenarios involving continuous processing and rapid workpiece type switching, a pre-scan operation is required before each workpiece can be marked, significantly increasing the preparation time for each product and leading to a decrease in overall line efficiency. This makes it difficult to meet the demands of modern industrial applications with fast production cycles, diverse product types, and high efficiency requirements.

[0006] In summary, existing height control technologies for inkjet printing equipment generally suffer from poor adaptability, large control delays, high structural rigidity, and low levels of intelligence when facing complex working conditions and varied workpiece surface features. These issues make it difficult to meet the higher requirements of intelligent manufacturing and flexible production lines for the automation and quality stability of inkjet printing. Especially in situations requiring high-precision inkjet printing on uneven surfaces, with significant undulations, varied shapes, or edges prone to collision, there is an urgent need for a new type of printhead height sensing and control device and method that is more responsive, structurally flexible, provides more comprehensive measurements, and has stronger adaptability, in order to achieve a high degree of intelligence, controllability, and high-quality output in the inkjet printing process. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention provides a ring height measurement and control device, method, and system for inkjet printers. The specific technical solution is as follows: A ring height measurement and control device for an inkjet printer includes a dual-ring induction structure mounted on the inkjet printer. The dual-ring induction structure forms an induction capacitor with the workpiece to be printed, and the height information of the inkjet printer is obtained through the induction capacitor value. The dual-ring induction structure includes an outer induction ring and an inner induction ring that are insulated from each other. The inner induction ring is used to obtain the induction capacitor reflecting the height information of the inkjet printer nozzle, and the outer induction ring is used to obtain the induction capacitor reflecting the height information of the periphery of the inkjet printer nozzle. Both the outer induction ring and the inner induction ring are provided with output connectors for outputting the induction capacitor information.

[0008] Furthermore, a position adjustment assembly is provided between the outer sensing ring and the inner sensing ring. The position adjustment assembly includes a sliding hinge, a telescopic rod, and a fixed hinge. One end of the sliding hinge is disposed in a groove circumferentially opened on the inner wall of the outer sensing ring, or is slidably engaged on a slide rail circumferentially arranged on the inner wall of the outer sensing ring. 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 inner sensing ring through the fixed hinge. At least one of the sliding hinge, the telescopic rod, and the fixed hinge is an insulator.

[0009] Furthermore, the sensing 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. The sleeve ring is equipped with a locking screw, which is used to lock the two ends of the metal strip in conjunction with the positioning hole opened on 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, which is used to adjust the size of the sensing outer ring.

[0010] Preferably, the inductive double-ring structure is further provided with an adhesive component for fixed connection with the inkjet printer, the adhesive component being a strong magnetic sheet or adhesive tape.

[0011] A method for measuring and controlling the height of an inkjet printer, comprising the following steps: Install the aforementioned ring height measuring and control device onto the inkjet printer; The ring height measurement and control device is connected to the signal processing circuit through the output connector to obtain a square wave signal containing induced capacitance information; The square wave signal is filtered and smoothed to obtain the frequency value of the square wave signal; The height of the inkjet printer nozzle and the frequency value of the square wave signal are calibrated. The frequency value of the square wave signal is acquired in real time, and the actual value of the inkjet printer nozzle height is obtained according to the calibration relationship, and then input into the inkjet printer servo control system.

[0012] Furthermore, the signal processing circuit includes a capacitor signal acquisition circuit and a filtering and comparison circuit; the capacitor 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 ring 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 filtering on the output signal of the shaping and enhancement circuit, and convert the filtered signal into a square wave signal through an operational amplifier comparator.

[0013] Furthermore, during the calibration of the inkjet printer height and the square wave signal frequency value, the inkjet printer servo control system continuously adjusts the actual height of the inkjet printer head from low to high or from high to low, and obtains the corresponding square wave signal frequency value, establishing a one-to-one correspondence between the inkjet printer head height and the square wave signal frequency value; for correspondences not obtained during calibration, they are determined by the difference method.

[0014] A height measurement and control system for an inkjet printer based on the above method includes a ring-shaped height measurement and control device installed on the inkjet printer, a signal processing circuit connected to the ring-shaped height measurement and control device, and a core processing module connected to the signal processing circuit. The core processing module is used to acquire the frequency value of the square wave signal output by the signal processing circuit, and output the actual value of the inkjet printer head height to the inkjet printer servo control system according to the calibration relationship between the square wave signal frequency value and the actual value of the inkjet printer head height. The inkjet printer servo control system adjusts the inkjet printer head height according to the deviation between the actual value of the printhead 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 head 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 head height and the square wave signal frequency value; for the correspondence not obtained during calibration, it is determined by the difference method.

[0016] Furthermore, it also includes a human-machine interaction module and an alarm prompting module; the human-machine interaction module is used to set system parameters and trigger operation control commands through a touch screen or input / output device; the alarm prompting 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 methods that rely on point laser rangefinders for single-point ranging, this invention achieves height sensing capability across a 360° range around the printhead using a ring-shaped capacitive sensing structure. This effectively avoids information distortion problems caused by limited installation location, single ranging direction, and measurement lag. The employed capacitive sensing structure is not limited by installation angle or direction and can provide real-time, high-precision height feedback signals during printhead movement. This ensures the printhead maintains a stable and appropriate printing distance throughout the entire coding path, significantly improving coding quality and process stability.

[0018] Furthermore, compared with existing pre-scanning modeling control methods, this invention significantly improves coding efficiency while maintaining control accuracy. Traditional modeling methods require a complete surface scan and mathematical modeling before each coding operation. Although this achieves a high degree of surface contour reproduction, the time-consuming modeling and complex data processing significantly reduce overall coding efficiency, especially in mass production scenarios where it severely impacts production cycle time. In contrast, this invention only requires one sensing distance calibration for similar workpieces, allowing parameters to be directly called in subsequent coding processes without repeated scanning and modeling operations. This enables a continuous and efficient follow-up coding process, greatly reducing coding preparation time and system response latency.

[0019] This invention also demonstrates excellent structural adaptability and ease of system integration. The dual-ring induction structure is made of red copper, which has excellent conductivity and high plasticity. The surface is coated with polyester resin, providing good insulation, rust prevention, and corrosion resistance, enabling it to adapt to complex and varied industrial environments. The modular design and magnetic installation method allow for rapid integration into various types of inkjet printers without significant modifications to the existing structure, effectively reducing deployment costs. Simultaneously, the system is equipped with a complete capacitance acquisition circuit, signal receiving and shaping amplification circuit, and a closed-loop control system composed of an FPGA and a core processor. This ensures high real-time adjustment capability while achieving high-precision and robust dynamic control.

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

[0021] In summary, this invention improves control precision, response speed, and system flexibility while also taking into account process adaptability, deployment convenience, and automation integration requirements. It provides an efficient, reliable, and industrially-oriented comprehensive solution to address the limitations in direction, low efficiency, and poor versatility of existing technologies. Attached Figure Description

[0022] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof.

[0023] Figure 1 This is a schematic diagram of a dual-ring sensing structure provided in an embodiment of the present invention; Figure 2 This is a circuit diagram for acquiring capacitance signals provided in an embodiment of the present invention; Figure 3 This is a physical diagram of a signal acquisition module provided in an embodiment of the present invention; Figure 4 This is a filter comparison circuit diagram provided in an embodiment of the present invention.

[0024] The reference numerals in the attached figures are as follows: 1-Induction outer ring, 2-Mounting component, 3-Adhesive component, 4-Outer ring locking screw, 5-Sliding hinge, 6-Telescopic rod, 7-Insulating hinge, 8-Telescopic rod locking screw, 9-Mounting component screw, 10-Cable, 11-Inner ring connector, 12-Outer ring connector. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative effort are all within the scope of protection of the present invention.

[0026] A ring height measurement and control device for an inkjet printer, such as Figure 1 As shown, the device includes a double-ring sensing structure consisting of an outer sensing ring 1 and an inner sensing ring. The outer sensing ring 1 is made of highly malleable red copper, formed by bending a single strip of red copper. The two ends of this strip of red copper are connected to each other via connecting rings. The connecting rings are equipped with outer ring locking screws 4, which are used to lock the two ends of the red copper through positioning holes. After removing the outer ring locking screws 4, the two ends of the red copper can slide relative to each other along the red copper via the connecting rings, allowing adjustment of the size of the outer sensing ring 1.

[0027] To facilitate cooperation with the inkjet printer, multiple adhesive parts 3 are installed on the outer sensing ring 1 via mounting parts 2. The adhesive parts 3 are made of strong magnetic sheets or strong adhesive, which can be magnetically attracted or pasted onto the surface of the inkjet printer.

[0028] The inner sensing ring is located inside the outer sensing ring 1 via multiple position adjustment components, including a sliding hinge 5, a telescopic rod 6, and an insulating hinge 7. One end of the sliding hinge 5 is slidably positioned in a groove or on a slide rail on the inner wall of the outer sensing ring 1, allowing it to slide circumferentially along the inner wall of the outer sensing 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 inner sensing ring via the insulating hinge 7. The telescopic rod 6 includes multiple sleeves that are nested together to allow for telescopic adjustment, and is also equipped with a telescopic rod locking screw 8 for locking the telescopic rod after its length has been adjusted. The insulating hinge 7 is used to block the electrical connection between the outer sensing ring 1 and the inner sensing ring. In fact, to prevent the outer sensing ring 1 and the inner sensing ring from conducting electricity, it is only necessary to block the conductivity of the position adjustment components 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 inner sensing ring. One end of the cable 10 is provided with an inner ring connector 11 for exporting the inner ring capacitance sensing signal. The cable 10 is wrapped with insulating material to prevent short circuits. Similarly, an outer ring connector 12 for exporting the outer ring capacitance sensing signal is also provided on the outer sensing ring 1. In some embodiments, for ease of wiring or cabling, the inner ring connector 11 can also be installed simultaneously on the outer sensing ring 1, but care should be taken to maintain insulation from the outer sensing ring 1. Specifically, the inner ring connector 11 and the outer ring connector 12 use an SMA interface for connection to the input node GC_INP of the capacitance signal acquisition device via a high-frequency coaxial cable.

[0030] The aforementioned dual-ring sensing structure is installed at the bottom of the inkjet printer. The thin sensing rings allow the printhead to be closer to the material being processed, thus supporting a wide adjustable height range. The inner ring is used for precise sensing of the printhead's range, while the outer ring, after adjustment, closely matches the external dimensions of the inkjet printer, used for edge detection and overall collision avoidance. The sensing structure, which fuses the data from the inner and outer rings, supports lateral distance detection of the printhead.

[0031] The main body of the dual-ring sensor is made of red copper, which has superior conductivity compared to existing materials such as stainless steel, resulting in more sensitive height feedback and significantly improved equipment stability. Red copper also boasts excellent ductility, reducing processing difficulty. In practical applications, the tail handle can be manually bent and cut in any direction to suit different inkjet printer sizes and installation spaces, greatly improving installation efficiency and reducing the difficulty of reprocessing due to different inkjet printer sizes and structures, making it suitable for various installation environments. The surface of the dual-ring sensor is coated with polyester resin, which significantly improves surface wear resistance, rust prevention, and ink corrosion resistance compared to pure metal rings currently on the market. This effectively eliminates wear and dirt problems caused by dust, ink, and other contaminants during use, facilitating daily cleaning and maintenance and extending the service life of the dual-ring sensor.

[0032] The dual-ring induction device is magnetically or adhesively attached to the inkjet printer via mounting clips, the number of which is optional. Compared to existing devices that rely solely on clamping at the end of the handle, this method offers more installation options, a smaller size, and superior anti-vibration and anti-deviation capabilities. It effectively reduces issues such as high-noise induction and alarm shutdowns caused by the dual-ring induction device shifting during high-speed operation, significantly improving production efficiency. The magnets in the mounting clips are encased in nylon and electrically isolated from the dual-ring induction device, ensuring no interference with the sensing effect. The mounting clips use a snap-fit ​​installation method, allowing for quick disassembly and maintenance of the dual-ring induction device. High wear resistance, oil resistance, and good dimensional stability effectively increase the lifespan of the fixture.

[0033] By installing the aforementioned ring height measuring device onto the inkjet printer and connecting it to the signal processing circuit via its output interface, the induced capacitance signal reflecting the height of the printer's printhead can be obtained. In this embodiment, the signal processing circuit includes a capacitance signal acquisition circuit and a filtering and comparison circuit.

[0034] like Figure 2 As shown, the capacitor signal acquisition circuit consists of three parts connected in sequence: a CLC parallel resonant circuit, a signal holding circuit, and a shaping and enhancement circuit. Figure 3 This is a physical diagram of the capacitor signal acquisition circuit. The right side shows the SMA interface, which connects to the induction loop via a high-frequency coaxial cable. The left side shows the power supply and output signal terminals.

[0035] (1) The core of the dual-ring SMA interface is electrically connected to GC_INP of the CLC parallel resonant circuit, and the grounding point PE of the equipment casing is electrically connected to GC_INN. The value of the sensing capacitor is usually in the range of 50-200pF. It 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. R18 and R19 form the base static operating voltage by voltage division. R21 is electrically connected to the emitter and PE to provide temperature negative feedback current and 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 path for the oscillation 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. The circuit has low output impedance and high input impedance, which plays 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, which can increase the signal amplitude and overcome signal attenuation during long-distance transmission. The inverting input terminal of the op-amp is electrically connected to R25 and R26, and the non-inverting input terminal is connected to the PE terminal via R27. The signal amplification factor is determined by the ratio of R25 and R26. Finally, a stable AC signal is output to the GC_OUT port. Note that the positive and negative voltages of the op-amp's input power rail should be equal in magnitude and opposite in sign. This ensures that the signal is not distorted within the power rail range, thereby ensuring that the receiver can accurately extract frequency information.

[0038] Figure 4The input terminal AS_IN of the filter comparator circuit is connected to the output terminal GC_OUT of the capacitor signal acquisition circuit via a coaxial cable. R132 and C183 form a pre-amplifier low-pass filter circuit, and R133 and C184 are connected in series to form a damped high-pass circuit. Together, they form a frequency selection circuit that can reliably extract signals from 0.5-3MHz. The signal is then passed through a subsequent operational amplifier comparator, which converts the smooth zero-crossing AC signal into a square wave signal with steep edges, and outputs it to the AS_OUT port.

[0039] The input pins of the FPGA (core processing module) are electrically connected to the AS_OUT port of the filter comparator circuit, receiving and processing square wave signals containing capacitance information. The FPGA oversamples the square wave signal at a clock frequency of 250MHz, measures the duration of each high-level pulse, and uses a median filter with a width of 10 and a moving average filter with a width of 200 to filter and obtain a smooth period value within a 1ms control cycle. This smoothed period value is then converted into a frequency value, processed, and used to obtain the position information as the feedback signal input for the inkjet printer height closed-loop control system.

[0040] The execution flow of the inkjet printer's closed-loop control system is as follows: (1) Read the frequency value calculated from the capacitor acquisition signal at a sampling frequency of 1 kHz (consistent with the control period). ; (2) Based on the calibration of the sensing distance The original distance values ​​are obtained by interpolation based on the scattered points. ; (3) Based on the electrical environment interference, the user sets the filter strength parameters, and based on this, sets the observation noise covariance matrix of the distance Kalman filter, and calculates the filtered distance value. ; (4) Based on the user-set target value for nozzle height In each control cycle, the nozzle height error for the current cycle is calculated. ; (5) Apply an adaptive proportional-integral controller in each control cycle. Adaptive adjustment of proportional control gain and integration time constant The adaptive control law is as follows: for small errors, a low proportional gain and a small integral time constant are used; for large errors, a high proportional gain and a large integral time constant are used. (6) Calculate the servo speed control quantity ; (7) Change the current servo control quantity and the value of the previous period Comparisons are made to prevent single-cycle acceleration from exceeding the set allowable value. This reduces mechanical vibration and ensures coding quality.

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

[0042] in To control the cycle.

[0043] (8) As a servo driver that inputs speed commands, it controls the vertical movement of the nozzle.

[0044] (9) According to The control cycle is executed cyclically from (1) to (8).

[0045] The aforementioned control system also includes human-machine interaction functions, such as parameter setting, sensing distance calibration, and motor jogging.

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

[0047] Sensing distance calibration: Tap 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 sensing ring and nozzle to descend slowly.

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

[0049] (3) When When the value exceeds the preset threshold or the capacitance value becomes 0, a trigger signal is activated.

[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 sensing double ring to stabilize and stop vibrating slightly.

[0052] (6) Send a speed command of -10rpm to the driver, and the sensing ring and nozzle will rise slowly for 10s.

[0053] (7) During the rise, the capacitance data and encoder feedback position are collected in each sampling period, and stored in the device memory in a one-to-one correspondence.

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

[0055] (9) The touchscreen displays "Sensing distance calibration complete" and indicates whether it was successful. If successful, follow-up coding is allowed; if it fails, follow-up coding is not allowed. Common causes of failure include electrical interference and unstable installation of the dual sensing rings.

[0056] Motor jogging: Used for manually adjusting the nozzle height. Clicking the touch button "Forward" or "Reverse" on the interface sends a constant speed command of 20 rpm or -20 rpm 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 sensing rings and the nozzle.

[0057] This embodiment defines a simple I / O handshake protocol based on two I / O ports and one output port for alarm shutdown. It can realize follow-up coding and alarm output functions, requiring minimal software development and is very suitable for addition as an independent module to PLC and other automation equipment. One of the two I / O ports is the input follow-up start signal, and the other is the output follow-up stop signal. This device uses these two ports to implement the handshake protocol and coding action with the host system (e.g., PLC) according to the following process.

[0058] (1) Before starting the follow-up inkjet printing, ensure that the sensing distance calibration has been performed and successfully.

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

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

[0061] (4) The equipment executes the control process of the closed-loop control system. The moving nozzle and the sensing double ring reach a position of ±0.1mm near the specified height, and the instantaneous speed calculated by the encoder feedback is less than 5rpm.

[0062] (5) The device outputs a follow-up positioning signal, which is received by the host system.

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

[0064] (7) Once the font or pattern is painted, the host system outputs an invalid signal (high level invalid) to this device, which is then read by the core processor chip.

[0065] (8) The host system performs closed-loop control based on encoder feedback, and the moving nozzle and sensing loop return to the initial position at the start of the follow-up.

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

[0067] The above summarizes the main content of this embodiment. Based on the principle of capacitive sensing, this embodiment designs a ring-shaped height measurement and control device with a dual-ring induction structure that can sense a 360° range, is easy to install, and highly versatile. It should be noted that the dual-ring induction structure is not limited to a perfect circle; any structure with a closed outer contour should be included within the protection range, such as rectangles, ellipses, triangles, etc. This embodiment designs a dedicated capacitance acquisition unit for the electrical structure of the dual-ring induction system, including a CLC parallel resonant circuit, a holding circuit, a shaping circuit, a filtering circuit, and a comparison circuit. This embodiment also designs a motion flow based on two I / O ports, which can easily communicate with a PLC to achieve follow-up coding. The programming is simple, and it can be easily embedded as an independent module into complex automated equipment.

[0068] Unlike laser rangefinders, this invention measures nozzle height using capacitive sensing. While also a non-contact measurement method, this invention offers a wider sensing range, is not limited by installation location, and is more versatile in installation methods.

[0069] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented using software plus a general-purpose hardware platform, or of course, using hardware. Based on this understanding, the above technical solutions, in essence or the parts that contribute to the related 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, magnetic disk, optical disk, etc.), including several instructions for executing the methods described in the above embodiments or some parts 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, and not to limit them; under the concept of the present invention, the technical features of 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, which are not provided in detail for the sake of brevity; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A ring height measuring and control device for an inkjet printer, characterized in that, The device includes a dual-ring sensing structure mounted on an inkjet printer. The dual-ring sensing structure forms a sensing capacitor with the workpiece to be printed, and the height information of the inkjet printer is obtained through the sensing capacitor value. The dual-ring sensing structure includes an outer sensing ring and an inner sensing ring that are insulated from each other. The inner sensing ring is used to obtain the sensing capacitor reflecting the height information of the inkjet printer nozzle, and the outer sensing ring is used to obtain the sensing capacitor reflecting the height information of the periphery of the inkjet printer nozzle. Both the outer sensing ring and the inner sensing ring are provided with output connectors for outputting the sensing capacitor information.

2. The annular height measurement and control device as described in claim 1, characterized in that, A position adjustment assembly is provided between the outer sensing ring and the inner sensing ring. The position adjustment assembly includes a sliding hinge, a telescopic rod, and a fixed hinge. One end of the sliding hinge is disposed in a groove circumferentially opened on the inner wall of the outer sensing ring, or is slidably engaged on a slide rail circumferentially arranged on the inner wall of the outer sensing ring. 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 inner sensing ring through the fixed hinge. At least one of the sliding hinge, the telescopic rod, and the fixed hinge is an insulator.

3. The annular height measurement and control device as described in claim 1, characterized in that, The sensing outer ring is formed by bending a metal strip. The two ends of the metal strip are connected to each other by a sleeve ring, and the sleeve ring is equipped with a locking screw. The locking screw is used to lock the two ends of the metal strip by engaging with the positioning hole on 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, which is used to adjust the size of the sensing outer ring.

4. The annular height measurement and control device as described in claim 1, characterized in that, The inductive double-ring structure is also provided with an adhesive component for fixed connection with the inkjet printer, the adhesive component being a strong magnetic sheet or adhesive tape.

5. A method for height measurement and control of an inkjet printer, characterized in that, Including the following steps: Install the annular height measuring and control device according to any one of claims 1 to 4 onto the inkjet printer; The ring height measurement and control device is connected to the signal processing circuit through the output connector to obtain a square wave signal containing induced capacitance information; The square wave signal is filtered and smoothed to obtain the frequency value of the square wave signal; The height of the inkjet printer nozzle and the frequency value of the square wave signal are calibrated. The frequency value of the square wave signal is acquired in real time, and the actual value of the inkjet printer nozzle height is obtained according to the calibration relationship, and then input into the inkjet printer servo control system.

6. The inkjet printer height measurement and control method as described in claim 5, characterized in that, The signal processing circuit includes a capacitor signal acquisition circuit and a filtering and comparison circuit. The capacitor 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 ring height measurement and control device. 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 filtering on the output signal of the shaping and enhancement circuit, and convert the filtered signal into a square wave signal through an operational amplifier comparator.

7. The inkjet printer height measurement and control method as described in claim 5, characterized in that, When calibrating the inkjet printer height and the square wave signal frequency value, the inkjet printer servo control system continuously adjusts the actual height of the inkjet printer head from low to high or from high to low, and obtains the corresponding square wave signal frequency value, establishing a one-to-one correspondence between the inkjet printer head height and the square wave signal frequency value; for correspondences not obtained during calibration, they are determined by the difference method.

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

9. The inkjet printer height measurement and control system as described 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 head 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 head height and the square wave signal frequency value; for the correspondence not obtained during calibration, it is determined by the difference method.

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

Images