Automatic leveling and height adjusting device of 3D printer and control circuit of automatic leveling and height adjusting device

Abstract

The invention discloses an automatic leveling and height adjusting device for a 3D printer and a control circuit thereof.The automatic leveling and height adjusting device comprises a hot bed, springs are arranged below the four corners of the hot bed, a piezoelectric sensor is arranged below the hot bed, and the piezoelectric sensor is connected with an input channel of a main control panel; the piezoelectric sensor is provided with a vibration sensing mechanism or a pressure sensing mechanism. The invention belongs to the field of FDM 3D printing, and particularly relates to an automatic leveling and height adjusting device of a 3D printer and a control circuit of the automatic leveling and height adjusting device. A plurality of piezoelectric ceramic vibration sensing modules are arranged between a bearing base on a machine body and a printing platform, a control panel receives signals of a plurality of sensors for comprehensive analysis and comparison through vibration or pressure generated instantly when a printing nozzle touches the printing platform, and the signals are fed back to a printer mainboard to generate net bed compensation; and meanwhile, automatic height alignment of the full-breadth spray head is achieved, the mainboard controls the motor to automatically ascend and descend to compensate the height of the net bed according to detection data during printing, and the automatic leveling function is achieved.

Description

Technical Field

[0001] This invention belongs to the field of FDM 3D printing technology, specifically referring to an automatic leveling and height adjustment device and its control circuit for a 3D printer. Background Technology

[0002] In the field of 3D printing, the leveling accuracy of the printing platform is crucial to print quality, making automatic leveling and alignment devices core components. Currently, the three mainstream automatic leveling solutions all have significant shortcomings. The vibration sensor matrix-based solution uses ADXL345 accelerometers to form a matrix component, installed in the print head leveling device to detect changes in the vertical position of the platform and print head. In the control module, the DSP receives the signals and combines them with a leveling algorithm to calculate the tilt angle and compensation value, which the MCU then uses to control the print head movement. However, the sensors in this solution are susceptible to vibration interference from the machine itself and surrounding equipment, affecting detection accuracy. Furthermore, the multi-sensor matrix not only increases hardware costs, but its coordination and calibration also require additional technical and cost investment. The strain gauge-based solution assembles a sensor and a strain gauge in the print head. When the sensor deforms upon contact with the heated bed, the strain gauge converts pressure into a voltage signal. The control board determines the contact state by comparing it with a threshold value, then calculates the adjustment amount using an algorithm, driving the motor to adjust the print head's height. However, strain gauge performance is easily affected by usage time and temperature. For example, temperature changes alter its coefficient of thermal expansion, leading to inaccurate signals. The assembly of the inductor and strain gauge places high demands on the printhead structure design, increasing complexity, and assembly accuracy directly impacts performance. Signal processing is complex, requiring high-performance control boards. A pressure sensing module-based solution places pressure sensing, leveling, and signal processing modules between the support base and the printing platform. Thin-film pressure sensors detect the pressure between the four corners of the platform and the base. The microcontroller receives the signal and compares it with the set pressure, then controls a micro-stepper motor to drive the leveling nut, adjusting the screw length to achieve leveling. However, thin-film pressure sensors are affected by uneven pressure distribution and accuracy limitations; inconsistent accuracy at the four corners can lead to errors. The complex mechanical structure and the stepper motor-driven nut and screw structure are prone to seizing and step loss, affecting reliability and lifespan. Summary of the Invention

[0003] In order to overcome the shortcomings of the prior art, the present invention provides an automatic leveling and height adjustment device and its control circuit for a 3D printer, which effectively solves the problems existing in the current market for automatic leveling of heated beds and determination of the relative height of nozzles, such as the cumbersome manual leveling and reliance on experience, the large error of traditional automatic leveling, the need for manual calibration of deviations and limited adaptability.

[0004] The technical solution adopted by the present invention is as follows: The present invention proposes an automatic leveling and height adjustment device and its control circuit for a 3D printer, including a heated bed, with springs installed at the four corners of the heated bed, and piezoelectric sensors installed below the heated bed. The piezoelectric sensors are connected to the input channel of the main control board, and vibration sensing mechanism or pressure sensing mechanism is installed on the piezoelectric sensors.

[0005] Furthermore, the pressure sensing mechanism includes a mounting bolt, which is located at the four corners of the heated bed. A spring is fitted on the mounting bolt, and a heated bed base is located below the spring. The heated bed base passes through and is threadedly connected to the mounting bolt. A leveling nut is threadedly connected to the bottom of the mounting bolt. A sensor mounting support is located below the heated bed base and is connected to the piezoelectric sensor.

[0006] Furthermore, the sensor mounting bracket includes a sensor detection base and a heated bed base fixing seat. The heated bed base fixing seat is fixedly connected to the piezoelectric sensor through the piezoelectric sensor mounting position set in the middle, and the heated bed base fixing seat is threadedly connected to the mounting bolt one through the heated bed bolt through hole set at the front end. The heated bed base fixing seat is set above the leveling nut one, and the end of the heated bed base fixing seat away from the mounting bolt one is engaged with the slot above the sensor detection base.

[0007] Furthermore, the bolt positioning holes on the heated bed base and the sensor base fixing threaded holes on the sensor detection base are fixed by four sets of bolts. The heated bed base fixing through hole at the end of the sensor detection base away from the sensor base fixing threaded hole is fixed to the heated bed base by two sets of bolts. One end of the spring is connected to the heated bed, and the other end of the spring is connected to the heated bed base.

[0008] Furthermore, the vibration sensing mechanism includes two mounting bolts, which are located at the four corners below the heated bed. A spring is fitted on the two mounting bolts. The two mounting bolts pass through and are threadedly connected to the heated bed base. A sensor mounting bracket passes through and is threadedly connected to the two mounting bolts. A piezoelectric sensor is mounted above the sensor mounting bracket. The sensor mounting bracket is located above the heated bed base. A leveling nut is located below the sensor mounting bracket and is threadedly connected to the two mounting bolts.

[0009] Furthermore, the main control board includes a linked signal acquisition and processing circuit, an independent signal acquisition and processing circuit, a signal processing and output circuit, and a power switching circuit for an independent signal acquisition channel.

[0010] Furthermore, the main control board is equipped with four linked signal acquisition and processing circuits. The signal acquisition and processing circuit includes an operational amplifier. The inverting input terminal of the operational amplifier is connected to the sensor input port CN1 via GND and is connected in parallel with the pull-down resistor R3 and the filter capacitor C1.

[0011] The sensitivity adjustment resistors R1 and R2 are connected in series to VCC and the non-inverting input terminal of the operational amplifier.

[0012] The current-limiting resistor LED1 and R5 are connected in series to VCC and the output terminal of the operational amplifier. The output terminal is also connected to the pull-up resistor R4 and the filter capacitor C2.

[0013] The piezoelectric sensor port is connected to the CN1 socket. The trigger sensitivity is adjusted by the variable resistor R2. After processing by the LM358 operational amplifier, the operational amplifier outputs a high-level signal by default. When the trigger strength is greater than the adjusted sensitivity, it outputs a low-level signal and the LED1 indicator lights up.

[0014] Furthermore, the main control board has two independent signal acquisition and processing circuits, which can independently connect to two sensors and output signals independently. The signal acquisition and processing circuit includes a voltage comparator. The sensor input port CN6 is connected to the inverting input of the voltage comparator and a pull-down resistor R4 is connected in parallel with GND. The sensitivity adjustment resistors R1 and R2 are connected in series with VCC and in parallel with GND and C2 to provide an adjustable reference voltage for the non-inverting input. ZD1 is connected in parallel between the inverting input of the voltage comparator and ground. The comparator output is connected to the gate of a P-MOS transistor, a pull-up resistor R5 to VCC, and a filter capacitor C1 to GND. The drain of the P-MOS transistor is connected to GND, and the source is connected to a pull-down resistor R4 and C1 as the output. The LED is connected in series with R7 to VCC and the drain side of the P-MOS transistor. In one circuit, the comparator output can be connected to a multi-channel signal processing circuit via a DIP switch SW as a linkage signal. The sensitivity is adjusted by R1 and processed by an LM393. When the trigger strength exceeds the sensitivity, the comparator output flips to a low level, the P-MOS transistor is turned on, the LED lights up, and the output is low.

[0015] Furthermore, the signal processing and output circuit receives the output signal of the signal acquisition circuit and further processes it into a pulse signal that can be directly read by the FDM printer main control board. This circuit consists of three parts: the output signal processing of the signal acquisition circuit, a monostable trigger, and an interface with the FDM printer main control board.

[0016] The output signal processing uses a four-channel logic AND gate chip, which receives four linkage signals and controls whether an independent signal is linked via a DIP switch. After processing, the signal is output to a monostable multivibrator via a filter capacitor C1 and a resistor R1.

[0017] The monostable multivibrator includes a 555 timer chip, etc. The trigger end is connected to the logic gate output, the threshold end and the discharge end form a charging and discharging circuit with R3 and C2, the output end is connected to the N-MOS gate via R4, its drain is connected to the printer motherboard interface via R6, and its source is connected to GND. LED1 is connected in series with R5 to VCC and the output end.

[0018] The main control board interface includes a 3P port U4, etc. The signal pins are connected to the drain of the N-MOS. The power supply is connected from the printer motherboard. When the power is turned on, LED2 lights up. The logic gate output signal triggers the 555 timer chip to output a rectangular pulse, which drives the N-MOS to conduct, LED1 lights up, and the interface outputs a low-level pulse to trigger the printer to operate.

[0019] Furthermore, the main control board is equipped with a power switching circuit for an independent signal acquisition channel. The power switching circuit includes a dual-channel switch SW2, an independent power indicator LED, and a current-limiting resistor R1. The common terminal of the dual-channel switch serves as the power port for the independent signal acquisition and processing circuit. The other two sets of ports are the motherboard power supply VCC and GND and the external independent input power supply, respectively. The power supply for the independent signal acquisition and processing circuit can be switched by the switch to be directly connected to the motherboard power supply or to use other external power supplies.

[0020] The beneficial effects of this invention using the above structure are as follows: This solution proposes an automatic leveling and height alignment device and its control circuit for a 3D printer. Through single-chip microcomputer control, piezoelectric ceramic sensing, and other technologies, it achieves precise determination of the automatic leveling of the heated bed and the relative height of the nozzle, solving the drawbacks of manual leveling or traditional automatic leveling modes. Simultaneously, through modular design, it is widely compatible with various FDM printer structures and their main control boards on the market, simplifying the installation and debugging process, improving printing quality, and reducing the impact of manual adjustment errors. This method utilizes the vibration or pressure generated when the print head touches the printing platform. The control board receives signals from multiple sensors, analyzes and compares them, and feeds back to the printer's main board to generate wire bed compensation. Simultaneously, it achieves automatic height alignment of the full-width print head. During printing, the main board controls the motor to automatically raise and lower the wire bed height based on the detection data, achieving automatic leveling. Furthermore, the circuit design of this invention is a non-customized module, with high adaptability, small size, and ease of use. It can be directly adopted according to the existing printer structure and its main control board, based on the required workflow. Installation and debugging are simple, making it suitable for a wider range of scenarios, such as individual users and small businesses. The development cycle is relatively short, and the cost is low. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the pressure sensing installation method of the automatic leveling and height adjustment device and its control circuit for a 3D printer proposed in this invention.

[0022] Figure 2The above view shows the installation method of the automatic leveling and height adjustment device and its control circuit of a 3D printer proposed in this invention, which mainly uses pressure sensing and also takes vibration sensing into account.

[0023] Figure 3 This is a partial schematic diagram of the automatic leveling and height adjustment device and its control circuit for a 3D printer proposed in this invention, which is mainly based on pressure sensing and also takes vibration sensing into account.

[0024] Figure 4 This is a schematic diagram of a heated bed base for an automatic leveling and height adjustment device and its control circuit for a 3D printer proposed in this invention.

[0025] Figure 5 This is a schematic diagram of the sensor detection base of an automatic leveling and height adjustment device and its control circuit for a 3D printer proposed in this invention.

[0026] Figure 6 This is a schematic diagram of the vibration sensing installation method of an automatic leveling and height adjustment device and its control circuit for a 3D printer proposed in this invention.

[0027] Figure 7 This is a schematic diagram of the sensor mounting bracket for an automatic leveling and height adjustment device and its control circuit for a 3D printer proposed in this invention.

[0028] Figure 8 This is a schematic diagram of the signal acquisition and processing circuit for the linkage between the automatic leveling and height adjustment device and its control circuit of a 3D printer proposed in this invention.

[0029] Figure 9 This is a schematic diagram of an independent signal acquisition and processing circuit for an automatic leveling and height adjustment device and its control circuit for a 3D printer proposed in this invention.

[0030] Figure 10 This is a schematic diagram of the signal processing and output circuit of an automatic leveling and height adjustment device and its control circuit for a 3D printer proposed in this invention.

[0031] Figure 11 This is a schematic diagram of the power switching circuit for the independent signal acquisition channel of the automatic leveling and height adjustment device and its control circuit of a 3D printer proposed in this invention.

[0032] The components are as follows: 1. Heated bed; 2. Spring; 3. Heated bed base one; 4. Leveling nut one; 5. Mounting bolt one; 6. Sensor mounting bracket one; 6-1. Sensor detection base; 6-11. Sensor base fixing threaded hole; 6-12. Heated bed bottom fixing through hole; 6-2. Heated bed bottom fixing seat; 6-21. Bolt positioning hole; 6-22. Piezoelectric sensor mounting position; 6-23. Heated bed bolt through hole; 7. Piezoelectric sensor; 8. Sensor mounting bracket two; 9. Heated bed base two; 10. Leveling nut two; 11. Mounting bolt two.

[0033] 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. Detailed Implementation

[0034] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0035] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0036] Example 1:

[0037] like Figures 1-10 As shown, the present invention proposes an automatic leveling and height adjustment device and its control circuit for a 3D printer, including a heated bed 1, with springs 2 installed at the four corners of the heated bed 1, and piezoelectric sensors 7 installed below the heated bed 1. The piezoelectric sensors 7 are connected to the input channel of the main control board, and a vibration sensing mechanism or a pressure sensing mechanism is installed on the piezoelectric sensors 7.

[0038] In practical use, springs 2 located at the four corners of the heated bed 1 provide elastic support. These springs, with a stiffness of 4-6 N / mm and a compression of 5-8 mm, buffer the impact force when the printhead contacts the heated bed. The piezoelectric sensor 7 located below the heated bed can be installed using either vibration sensing or pressure sensing methods to capture minute vibrations or pressure changes at the moment the printhead touches the heated bed 1, transmitting the signal to the main control board's input channel. After analyzing and processing the signal, the main control board determines the zero relative height between the printhead and the heated bed 1, simultaneously completing automatic leveling and alignment. This integrated automatic leveling and printhead alignment function eliminates the need for additional probes or proximity switches, simplifying the structure. The high sensitivity of the piezoelectric sensor 7 ensures accurate detection, and the spring supports adapt to different heated bed flatness levels, making it widely compatible with various FDM printers; older models can be directly retrofitted.

[0039] The pressure sensing mechanism includes mounting bolts 5, which are located at the four corners of the heated bed 1. Springs 2 are fitted on the mounting bolts 5, and heated bed bases 3 are located below the springs 2. The heated bed bases 3 are threaded through and connected to the mounting bolts 5. A leveling nut 4 is threaded to the bottom of the mounting bolts 5. A sensor mounting bracket 6 is located below the heated bed base 3, and the sensor mounting bracket 6 is connected to the piezoelectric sensor 7.

[0040] In practical use, in the pressure sensing mechanism, mounting bolts 5 fix the four corners of the heated bed 1, and springs 2 are fitted onto the bolts, both supporting the heated bed and allowing for slight sinking; the bolts pass through the heated bed base 3, and the leveling nut 4 can initially adjust the height of the heated bed. The sensor mounting bracket 6 is connected to the piezoelectric sensor 7. When the nozzle touches the heated bed 1, the heated bed 1 sinks slightly, causing the sensor mounting bracket 6 to deform. The piezoelectric sensor 7 detects the pressure change and feeds it back to the main control board.

[0041] The sensor mounting bracket 6 includes a sensor detection base 6-1 and a heated bed base fixing seat 6-2. The heated bed base fixing seat 6-2 is fixedly connected to the piezoelectric sensor 7 through the piezoelectric sensor mounting position 6-22 set in the middle, and the heated bed base fixing seat 6-2 is threadedly connected to the mounting bolt 5 through the heated bed bolt through hole 6-23 set at the front end. The heated bed base fixing seat 6-2 is set above the leveling nut 4, and the end of the heated bed base fixing seat 6-2 away from the mounting bolt 5 is engaged with the slot above the sensor detection base 6-1.

[0042] In practical use, the heated bed base 6-2 of the sensor mounting bracket 6 fixes the piezoelectric sensor 7 through the piezoelectric sensor mounting position 6-22. The front heated bed bolt through hole 6-23 is nested with the mounting bolt 5, and the rear end is engaged with the slot of the sensor detection base 6-1, forming a stable force transmission path. The leveling nut 4 is located below the heated bed base 6-2 and can finely adjust the height of the heated bed 1 to match the sensor sensitivity. The engagement and bolt work together to ensure that pressure changes are transmitted to the sensor without loss, improving detection consistency. The leveling nut 4, together with the spring 2, realizes the horizontal pre-adjustment of the heated bed 1, laying the foundation for accurate detection.

[0043] The bolt positioning hole 6-21 on the heated bed base 6-2 and the sensor base fixing threaded hole 6-11 on the sensor detection base 6-1 are fixed by four sets of bolts. The heated bed base fixing through hole 6-12 at the end of the sensor detection base 6-1 away from the sensor base fixing threaded hole 6-11 is fixed to the heated bed base 3 by two sets of bolts. One end of the spring 2 is connected to the heated bed 1, and the other end of the spring 2 is connected to the heated bed base 3.

[0044] In practical use, the bolt positioning holes 6-21 of the heated bed base fixing seat 6-2 and the sensor base fixing threaded holes 6-11 of the sensor detection base 6-1 are fastened with four sets of bolts to ensure that there is no relative displacement between the two. The sensor detection base 6-1 is connected to the heated bed base 3 through the heated bed base fixing through hole 6-12. The two ends of the spring 2 are connected to the heated bed 1 and the heated bed base 3 respectively, providing continuous preload force. Multiple fixings prevent signal distortion caused by loose parts, and the spring preload force ensures that the heated bed 1 and the sensor mounting support 6 are in close contact, with uniform deformation when pressure changes, resulting in more accurate sensor detection.

[0045] Example 2:

[0046] The vibration sensing mechanism includes mounting bolt 211, which is located at the four corners of the heated bed 1. Spring 2 is sleeved on the mounting bolt 211. The mounting bolt 211 passes through and is threadedly connected to the heated bed base 29. The mounting bolt 211 passes through and is threadedly connected to the sensor mounting support 28. A piezoelectric sensor 7 is installed above the sensor mounting support 28. The sensor mounting support 28 is located above the heated bed base 29. A leveling nut 20 is located below the sensor mounting support 28 and is threadedly connected to the mounting bolt 211.

[0047] In practical use, in the vibration sensing mechanism, mounting bolt 211 passes through heated bed base 29 and sensor mounting bracket 28, and spring 2 provides preload to ensure a tight fit between the bracket and the heated bed base; leveling nut 210 adjusts the heated bed level, and piezoelectric sensor 7 is mounted above the bracket. The vibration generated when the printhead touches the heated bed 1 is transmitted to the sensor via heated bed base 29, triggering signal feedback. Leveling nut 210 is used to directly level the heated bed and ensure the overall structural stability, making it more suitable for printer types with large heated bed areas or compact overall structures.

[0048] Example 3:

[0049] The main control board includes a linked signal acquisition and processing circuit, an independent signal acquisition and processing circuit, a signal processing and output circuit, and a power switching circuit for an independent signal acquisition channel.

[0050] In practical use, the main control board's signal acquisition and processing circuit receives signals from the piezoelectric sensor, amplifies, filters, and compares them, and then converts them into standard electrical signals. The signal processing and output circuit converts the acquired signals into pulse signals that the printer's main control board can recognize. The power switching circuit for the independent signal acquisition channel adapts to different power supply requirements, ensuring circuit compatibility with various printer motherboards. The modular circuit design requires no customization, has strong adaptability, and can be directly connected to existing printer main control boards. Multi-channel signal processing supports multi-sensor collaborative work, improving detection coverage and accuracy, and simplifying the installation and debugging process.

[0051] The main control board has a total of four linked signal acquisition and processing circuits. The signal acquisition and processing circuit includes an operational amplifier. The inverting input terminal of the operational amplifier is connected to the sensor input port CN1 via GND and is connected in parallel with the pull-down resistor R3 and the filter capacitor C1.

[0052] Sensitivity adjustment resistors R1 and R2 are connected in series to VCC and the non-inverting input of the operational amplifier;

[0053] The current-limiting resistor LED1 and R5 are connected in series to VCC and the output of the operational amplifier. The output is also connected to the pull-up resistor R4 and the filter capacitor C2.

[0054] The piezoelectric sensor port is connected to the CN1 socket. The trigger sensitivity is adjusted by the variable resistor R2. After processing by the LM358 operational amplifier, the operational amplifier outputs a high-level signal by default. When the trigger strength is greater than the adjusted sensitivity, it outputs a low-level signal and the LED1 indicator lights up.

[0055] In practical use, in the four-channel linkage signal acquisition and processing circuit, the piezoelectric sensor signal is input to the operational amplifier via CN1, and the input signal is stabilized by the pull-down resistor R3 and the filter capacitor C1. The sensitivity adjustment resistors R1 and R2 set the trigger threshold, and the LM358 operational amplifier amplifies and compares the signal. The default output is high level, and when the trigger strength exceeds the threshold, the output is low level, and LED1 lights up as an indicator. The linkage circuit can process four sensor signals simultaneously, and by adjusting the sensitivity, it adapts to the vibration or pressure characteristics of different materials in the heated bed 1, ensuring the consistency of detection at each point and providing accurate data for mesh bed compensation.

[0056] The main control board has two independent signal acquisition and processing circuits, which can independently connect to two sensors and output signals independently. The signal acquisition and processing circuit includes a voltage comparator. The sensor input port CN6 is connected to the inverting input of the voltage comparator and a pull-down resistor R4 is connected in parallel with GND. The sensitivity adjustment resistors R1 and R2 are connected in series with VCC and in parallel with GND. C2 is connected in parallel with GND to provide an adjustable reference voltage for the non-inverting input. ZD1 is connected in parallel between the inverting input of the voltage comparator and ground. The comparator output is connected to the gate of the P-MOS, and a pull-up resistor R5 is connected to VCC and a filter capacitor C1 is connected to GND. The drain of the P-MOS is connected to GND, and the source is connected to a pull-down resistor R4 and C1 as the output. The LED is connected in series with R7 to VCC and the drain side of the P-MOS. The comparator output in one circuit can be connected to a multi-channel signal processing circuit as a linkage signal via a DIP switch SW. The sensitivity is adjusted by R1 and processed by LM393. When the trigger strength exceeds the sensitivity, the comparator output flips to a low level, the P-MOS is turned on, the LED lights up and outputs a low level.

[0057] In practical use, the two independent signal acquisition and processing circuits consist of two paths. The sensor signal is input to the CN6 voltage comparator, protected by the ZD1 Zener diode, and the reference voltage is adjusted by R1 to set the sensitivity. The LM393 comparator compares the input signal with the reference voltage, and upon triggering, outputs a low level, driving the P-MOS transistor to conduct, illuminating the LED, and independently outputting a low level. One path can be connected to the linkage circuit via a DIP switch. The independent circuit supports individual detection of specific areas, and the DIP switch flexibly switches between linkage / independent modes to adapt to different printing needs. The voltage comparator has a fast response speed, ensuring that the signal is triggered the instant the printhead contacts, improving high precision.

[0058] The signal processing and output circuit receives the output signal from the signal acquisition circuit and further processes it into a pulse signal that can be directly read by the FDM printer main control board. This circuit consists of three parts: the output signal processing of the signal acquisition circuit, a monostable trigger, and an interface with the FDM printer main control board.

[0059] The output signal processing uses a four-channel logic AND gate chip, which receives four linkage signals and controls whether an independent signal is linked via a DIP switch. After processing, the signal is output to a monostable multivibrator via a filter capacitor C1 and a resistor R1.

[0060] The monostable multivibrator includes a 555 timer chip, etc. The trigger terminal is connected to the logic gate output, the threshold terminal and the discharge terminal form a charging and discharging circuit with R3 and C2, the output terminal is connected to the N-MOS gate through R4, its drain is connected to the printer motherboard interface through R6, and the source is connected to GND. LED1 is connected in series with R5 to VCC and the output terminal.

[0061] The main control board interface includes a 3P port U4, etc. The signal pins are connected to the drain of the N-MOS. The power supply is connected from the printer motherboard. When the power is turned on, LED2 lights up. The logic gate output signal triggers the 555 timer chip to output a rectangular pulse, which drives the N-MOS to conduct, and LED1 lights up. The interface outputs a low-level pulse to trigger the printer to operate.

[0062] In practical use, the signal processing and output circuit integrates four linked signals using a four-channel AND gate. A DIP switch controls whether the output of one of the independent signal acquisition and processing circuits is linked or output from its independent channel. A monostable multivibrator composed of a 555 timer chip converts the logic signal into a fixed-duration rectangular pulse, driving an N-MOS transistor to conduct. This pulse is output through the 3P port U4 to the printer motherboard's Z-axis limit interface, simulating a limit signal to trigger the motherboard's action. The AND gate ensures coordinated operation of multiple sensor signals, avoiding the limited detection range of a single sensor. The fixed-duration pulse signal conforms to the printer motherboard interface trigger signal standard, ensuring compatibility without modifying the motherboard program and achieving seamless integration of automatic leveling and height alignment.

[0063] The main control board is equipped with a power switching circuit for an independent signal acquisition channel. The power switching circuit includes a dual-channel switch SW2, an independent power indicator LED and its current-limiting resistor R1. The common terminal of the dual-channel switch is used as the power port for the independent signal acquisition and processing circuit. The other two sets of ports are the motherboard power supply VCC and GND and the external independent input power supply, respectively. The power supply for the independent signal acquisition and processing circuit can be switched by the switch to be directly connected to the motherboard power supply or to use other external power supplies.

[0064] In practical use, the power switching circuit for the independent signal acquisition channel selects the power source via the SW2 switch, and the LED indicator displays the power supply status. When the printer motherboard power supply is unstable, it can be switched to an external power supply to ensure stable operation of the signal acquisition circuit. The power switching function improves circuit adaptability and solves compatibility issues caused by differences in power supply between different printer motherboards; the indicator lights provide intuitive feedback on the power supply status, facilitating troubleshooting during installation and debugging, and lowering the barrier to entry for users.

[0065] The above is the overall workflow of this invention. Simply repeat this process the next time you use it.

[0066] The actual operation process is very simple and easy. When the piezoelectric sensor 7 is installed using pressure sensing as the main method, during automatic leveling and height alignment, the printer nozzle contacts the heated bed 1 and generates a slight pressure, causing the heated bed 1 and mounting bolt 5 to move slightly downward. Because the sensor detection base 6-2 is fixed to the heated bed base 3 at the rear and nested with the mounting bolt 5 at the front, a slight deformation will occur. The highly sensitive piezoelectric sensor 7 can accurately detect the pressure change and feed it back to the main control board. After processing the signal, the main control board informs the printer motherboard that the Z-axis height of that point is zero, and the printer rises to detect the next point, finally completing the plane detection of the heated bed 1. At the same time, because the piezoelectric sensor 7 is closely attached to the heated bed base 3, it can also perform vibration sensing, with a wider detection range and sensitivity.

[0067] When the piezoelectric sensor 7 under the heated bed is installed using a vibration sensing-based method, the slight impact vibration generated when the printer nozzle contacts the surface of the heated bed 1 during automatic leveling and height alignment will be read by the piezoelectric sensor 7 installed in the sensor mounting bracket 2 and fed back to the main control board. After processing the signals collected by one or more piezoelectric sensors 7, the main control board sends a signal to the printer motherboard indicating that the Z-axis height of that point has returned to zero. The printer automatically rises to detect the next point, ultimately completing the detection of the entire heated bed 1 plane. The mounting bolt 2 11 passes through the through hole at the front of the sensor mounting bracket 2 8, and the pressure of the spring 2 ensures tight contact between it and the heated bed base 2 9 to guarantee accurate transmission of vibration signals. The leveling nut 2 10 is used to directly level the heated bed 1 and ensure the overall structural stability.

[0068] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0069] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

[0070] The present invention and its embodiments have been described above. This description is not restrictive, and the accompanying drawings are only one embodiment of the present invention; the actual structure is not limited thereto. In conclusion, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the spirit of the invention, such designs should fall within the protection scope of the present invention.

Claims

1. An automatic leveling and height adjustment device for a 3D printer and its control circuit, characterized in that: It includes a heated bed (1), with springs (2) installed at the four corners of the heated bed (1), and a piezoelectric sensor (7) installed below the heated bed (1). The piezoelectric sensor (7) is connected to the input channel of the main control board, and a vibration sensing mechanism or a pressure sensing mechanism is installed on the piezoelectric sensor (7).

2. The automatic leveling and height adjustment device and its control circuit for a 3D printer according to claim 1, characterized in that: The pressure sensing mechanism includes a mounting bolt (5), which is located at the four corners of the heated bed (1). A spring (2) is fitted on the mounting bolt (5). A heated bed base (3) is located below the spring (2). The heated bed base (3) passes through and is threadedly connected to the mounting bolt (5). A leveling nut (4) is threadedly connected to the bottom of the mounting bolt (5). A sensor mounting support (6) is located below the heated bed base (3). The sensor mounting support (6) is connected to the piezoelectric sensor (7).

3. The automatic leveling and height adjustment device and its control circuit for a 3D printer according to claim 2, characterized in that: The sensor mounting bracket (6) includes a sensor detection base (6-1) and a heated bed base fixing seat (6-2). The heated bed base fixing seat (6-2) is fixedly connected to the piezoelectric sensor (7) through the piezoelectric sensor mounting position (6-22) set in the middle. The heated bed base fixing seat (6-2) is threadedly connected to the mounting bolt (5) through the heated bed bolt through hole (6-23) set at the front end. The heated bed base fixing seat (6-2) is set above the leveling nut (4). The end of the heated bed base fixing seat (6-2) away from the mounting bolt (5) is engaged with the slot above the sensor detection base (6-1).

4. The automatic leveling and height adjustment device and its control circuit for a 3D printer according to claim 3, characterized in that: The bolt positioning hole (6-21) on the heated bed base (6-2) and the sensor base fixing thread hole (6-11) on the sensor detection base (6-1) are fixed by four sets of bolts. The heated bed base fixing through hole (6-12) at the end of the sensor detection base (6-1) away from the sensor base fixing thread hole (6-11) is fixed to the heated bed base (3) by two sets of bolts. One end of the spring (2) is connected to the heated bed (1), and the other end of the spring (2) is connected to the heated bed base (3).

5. The automatic leveling and height adjustment device and its control circuit for a 3D printer according to claim 1, characterized in that: The vibration sensing mechanism includes mounting bolt two (11), which is located at the four corners of the heated bed (1). A spring (2) is sleeved on the mounting bolt two (11). The mounting bolt two (11) passes through and is threadedly connected to the heated bed base two (9). The mounting bolt two (11) passes through and is threadedly connected to the sensor mounting support two (8). A piezoelectric sensor (7) is installed above the sensor mounting support two (8). The sensor mounting support two (8) is located above the heated bed base two (9). A leveling nut two (10) is located below the sensor mounting support two (8). The leveling nut two (10) is threadedly connected to the mounting bolt two (11).

6. The automatic leveling and height adjustment device and its control circuit for a 3D printer according to claim 1, characterized in that: The main control board includes a linked signal acquisition and processing circuit, an independent signal acquisition and processing circuit, a signal processing and output circuit, and a power switching circuit for an independent signal acquisition channel.

7. The automatic leveling and height adjustment device and its control circuit for a 3D printer according to claim 6, characterized in that: The main control board is equipped with four-channel linked signal acquisition and processing circuits. The signal acquisition and processing circuit includes an operational amplifier. The inverting input terminal of the operational amplifier is connected to the sensor input port CN1 via GND and is connected in parallel with the pull-down resistor R3 and the filter capacitor C1. The sensitivity adjustment resistors R1 and R2 are connected in series to VCC and the non-inverting input terminal of the operational amplifier. The current-limiting resistor LED1 and R5 are connected in series to VCC and the output terminal of the operational amplifier. The output terminal is also connected to the pull-up resistor R4 and the filter capacitor C2. The piezoelectric sensor port is connected to the CN1 socket. The trigger sensitivity is adjusted by the variable resistor R2. After processing by the LM358 operational amplifier, the operational amplifier outputs a high-level signal by default. When the trigger strength is greater than the adjusted sensitivity, it outputs a low-level signal and the LED1 indicator lights up.

8. The automatic leveling and height adjustment device and its control circuit for a 3D printer according to claim 6, characterized in that: The main control board has two independent signal acquisition and processing circuits, which can independently connect to two sensors and output signals independently. The signal acquisition and processing circuit includes a voltage comparator. The sensor input port CN6 is connected to the inverting input of the voltage comparator and a pull-down resistor R4 is connected in parallel with GND. The sensitivity adjustment resistors R1 and R2 are connected in series with VCC and in parallel with GND and C2 to provide an adjustable reference voltage for the non-inverting input. ZD1 is connected in parallel between the inverting input of the voltage comparator and ground. The comparator output is connected to the gate of a P-MOS transistor, a pull-up resistor R5 to VCC, and a filter capacitor C1 to GND. The drain of the P-MOS transistor is connected to GND, and the source is connected to a pull-down resistor R4 and C1 as the output. The LED is connected in series with R7 to VCC and the drain side of the P-MOS transistor. In one circuit, the comparator output can be connected to a multi-channel signal processing circuit via a DIP switch SW as a linkage signal. The sensitivity is adjusted by R1 and processed by an LM393. When the trigger strength exceeds the sensitivity, the comparator output flips to a low level, the P-MOS transistor is turned on, the LED lights up, and the output is low.

9. The automatic leveling and height adjustment device and its control circuit for a 3D printer according to claim 6, characterized in that: The signal processing and output circuit receives the output signal from the signal acquisition circuit and further processes it into a pulse signal that can be directly read by the FDM printer main control board. The circuit consists of three parts: the output signal processing of the signal acquisition circuit, a monostable trigger, and an interface with the FDM printer main control board. The output signal processing uses a four-channel logic AND gate chip, which receives four linkage signals and controls whether an independent signal is linked via a DIP switch. After processing, the signal is output to a monostable multivibrator via a filter capacitor C1 and a resistor R1. The monostable multivibrator includes a 555 timer chip, etc. The trigger end is connected to the logic gate output, the threshold end and the discharge end form a charging and discharging circuit with R3 and C2, the output end is connected to the N-MOS gate via R4, its drain is connected to the printer motherboard interface via R6, and its source is connected to GND. LED1 is connected in series with R5 to VCC and the output end. The main control board interface includes a 3P port U4, etc. The signal pins are connected to the drain of the N-MOS. The power supply is connected from the printer motherboard. When the power is turned on, LED2 lights up. The logic gate output signal triggers the 555 timer chip to output a rectangular pulse, which drives the N-MOS to conduct, LED1 lights up, and the interface outputs a low-level pulse to trigger the printer to operate.

10. The automatic leveling and alignment device and its control circuit for a 3D printer according to claim 6, characterized in that: The main control board is equipped with a power switching circuit for an independent signal acquisition channel. The power switching circuit includes a dual-channel switch SW2, an independent power indicator LED, and a current-limiting resistor R1. The common terminal of the dual-channel switch serves as the power port for the independent signal acquisition and processing circuit. The other two sets of ports are the motherboard power supply VCC and GND and an external independent power input, respectively. The power supply for the independent signal acquisition and processing circuit can be switched by the switch to be directly connected to the motherboard power supply or to use other external power supplies.

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