Handheld high-precision ink-jet printing device and control method

Abstract

The handheld high-precision ink-jet printing device comprises a support of a U-shaped structure, side baffles are formed on the two sides, a lead screw is erected between the side baffles on the two sides, a lead screw is driven by a lead screw driving motor, an ink box moving assembly comprises an ink box base and a lead screw nut, and the lead screw nut is matched with the lead screw. The motion detection device is used for detecting the motion position of the ink box motion assembly to achieve closed-loop control, and the paper rolling structure is arranged at the bottom of the support and used for conveying printing paper. Through the ink-jet printing mode that the ink box is driven by the lead screw, the high-precision imaging effect can be achieved in a narrow space. In addition, signal feedback is carried out through the motion detection device, so that the printing precision and the printing effect are further improved, deviation correction is carried out through feedback signals, and errors caused by step loss of the stepping motor are reduced. And the error of the linear motion is judged through a detection result in a mode of converting the linear motion into the rotary motion.

Description

Technical Field

[0001] This invention relates to the field of printing camera technology, and in particular to a handheld high-precision inkjet printing device. Background Technology

[0002] Currently, printers on the market are generally divided into the following categories: One type is the instant camera, represented by Japanese Fujifilm and German Polaroid. The core technology of instant cameras is a chemical developing process. The imaging process is as follows: after the shutter is pressed, the photographic paper is pushed out by the camera's rollers. The rollers break the chemical packets, spreading the chemicals evenly onto the photosensitive layer. The chemicals react with the photosensitive layer, and depending on the exposure (light intensity), the dyes develop layer by layer, ultimately forming an image. This imaging principle inevitably leads to the following problems: uneven imaging (stripes, spots); completely white / black photos; color cast / dull colors; and incomplete chemical coverage. Many products use simple optical systems, resulting in underexposure (photos too dark), overexposure (photos too bright, washed out), and the flash not being able to be turned off.

[0003] The second type is a thermal children's print camera. The core principle of a thermal printer is that the print head heats paper coated with a special thermal coating (thermal paper), causing a localized chemical reaction that develops images or text. The core component is a row of extremely precise heating resistors (heating points) on the print head. These heating points are arranged in a line, and their number determines the horizontal resolution of the print. When the printer receives a print command, the control circuit precisely controls which heating points need to be heated and which do not. By controlling the on / off state of the heating points, rows of dots are formed on the paper, and these dots eventually combine to form the text, graphics, or barcodes we see. The disadvantages of this type of printer are that the printed content is not durable. Thermal paper exposed to light, heat, and chemicals (such as plasticizers) for a long time will gradually darken, causing the text to become blurred or even disappear completely. It is not suitable for documents that need to be preserved for a long time. In the children's market, this type of print camera is only offered as a gift or experiential product, and the image quality is poor, mostly around 2.16 million pixels (based on a 6-inch photo), and the image can only be black and white. For example, patent publication documents: CN222852330U, CN222337441U, etc.

[0004] The third type of printing camera is the dye-sublimation printing camera. Sublimation is the process by which a substance changes directly from a solid state to a gaseous state without passing through a liquid state. Dye-sublimation printing utilizes this physical phenomenon, turning solid dye into a gas, which then permeates into a medium, and finally cools and solidifies to form an image. A dye-sublimation printer is a professional device designed for images. It can produce high-quality photos with vibrant colors, smooth transitions, and strong durability. Especially in the fields of ID photos, photographic output, or personalized item customization, a dye-sublimation printer is the irreplaceable best choice, with a resolution of up to 8.6 million pixels (based on a 6-inch photo). Its biggest drawbacks are slow speed, specific and expensive consumables, and unsuitability for text. Therefore, this type of camera is generally used in professional photography studios. Currently, major brands of dye-sublimation printing cameras on the market include Hanyin, FAGOO, and Canon. The cameras themselves are expensive, the consumables are also expensive, and the consumables are not interchangeable.

[0005] Therefore, among the three types of printing cameras mentioned above, the first type has poor image quality (mainly prone to color cast), is more expensive, and larger in size, but has a fast imaging speed. The second type is more affordable, but has extremely poor image quality and cannot produce color effects, although it has a fast imaging speed. The third type has the best image quality (stable imaging and vibrant colors), but the body is more expensive, consumables are extremely expensive, consumables from different brands are not interchangeable, and the imaging speed is slow.

[0006] The purpose of this invention is to enrich the variety of printing camera products on the market, giving users more choices and the experience of high-quality products at low prices. By adopting a new printing technology solution, printing costs are reduced as much as possible, allowing users to use low-cost printing consumables while still providing good print quality. This addresses some of the shortcomings of existing technologies.

[0007] Because the quality of printed images depends on two parts: the photosensitive component and the imaging component. The photosensitive component mainly depends on the quality of the photosensitive chip. Current photosensitive chip technology is very mature and inexpensive, with a resolution reaching 200 million pixels. Therefore, there is significant room for improvement in the imaging accuracy of the corresponding printing component. Thus, this invention primarily focuses on designing to improve the accuracy of the printing imaging component. Summary of the Invention

[0008] The purpose of this invention is to overcome one of the above-mentioned defects and provide a handheld high-precision inkjet printing device.

[0009] The objective of this invention is achieved through the following means: A handheld high-precision inkjet printer includes a U-shaped support frame with side baffles on both sides. A lead screw is mounted between the two side baffles and driven by a lead screw drive motor. The ink cartridge motion assembly includes an ink cartridge holder and a lead screw nut. The lead screw nut cooperates with the lead screw to make the ink cartridge motion assembly reciprocate linearly along the lead screw. A motion detection device is used to detect the motion position of the ink cartridge motion assembly to achieve closed-loop control. A paper roll structure is set at the bottom of the support frame for feeding printing paper.

[0010] As a preferred embodiment, the motion detection device includes a rack, a gear assembly, and a detection circuit board. The rack and lead screw are arranged in parallel and mounted on a side baffle. The gear assembly is mounted on the cartridge motion assembly, and the rack and gear assembly mesh with each other. The detection circuit board is mounted on the cartridge motion assembly and is used to detect the rotational state of the gear assembly.

[0011] As a preferred embodiment, the gear assembly includes a gear, a rotating shaft, a sensor mounting part, and a bearing. The rotating shaft is mounted on the cartridge motion assembly via the bearing. The gear and the sensor mounting part are respectively located at both ends of the rotating shaft. The rotating shaft is perpendicular to the rack, and the gear and the rack mesh with each other. The sensor signal transmitting end is located on the sensor mounting part.

[0012] As a preferred embodiment, the detection circuit board is equipped with a magnetic induction sensor, and the sensor mounting part is equipped with a magnet that cooperates with it, for non-contact detection of gear rotation angle.

[0013] As a preferred embodiment, the detection circuit board is equipped with an angle sensor for calculating the rotation angle, and the sensor mounting part is coupled to the angle sensor.

[0014] As a preferred embodiment, a horizontal plate parallel to the rack is provided above the rack, and sensing components are provided at both ends of the horizontal plate to cooperate with the detection circuit board to identify the position of the ink cartridge moving components.

[0015] As a preferred embodiment, the cartridge motion assembly includes a cartridge holder, a mounting position, and two through holes. The cartridge holder is used to hold the cartridge, and the cartridge is fixed to the cartridge holder by magnetic attraction. The mounting position is a recessed structure for mounting a motion detection device. The two through holes are respectively used to cooperate with a stabilizing support rod and a lead screw. A lead screw nut is placed in the through hole that cooperates with the lead screw. The lead screw drive motor is a stepper motor.

[0016] A method for controlling the above-mentioned device includes the following steps: S1, the main control system sends a pulse signal to the stepper motor to drive the lead screw (3) to rotate; S2, the motion detection device (5) detects the actual position of the ink cartridge motion assembly (4) in real time; S3, compare the actual position with the expected position to determine whether a step has been lost; S4. If a step is lost, calculate the number of compensation pulses and adjust the subsequent pulse signals to correct the position deviation.

[0017] As a preferred option, it also includes: using a trapezoidal or triangular velocity curve to plan the motion trajectory of the ink cartridge motion component; automatically selecting the velocity curve type according to the motion distance to achieve smooth acceleration, constant speed, and deceleration.

[0018] As a preferred embodiment, the step loss detection and compensation method includes: calculating the deviation between the desired position and the actual position in each control cycle; if the deviation exceeds a preset threshold, it is determined as a step loss; calculating the number of compensation pulses based on the deviation value, and performing compensation by inserting pulses or adjusting the pulse frequency.

[0019] As a preferred option, it also includes: using an incremental PID control algorithm to perform closed-loop control of the position of the ink cartridge moving components; and achieving sub-pixel-level positioning accuracy through comprehensive adjustment of proportional, integral, and derivative parameters.

[0020] The beneficial effects of this invention are as follows: Inkjet printing using a lead screw-driven ink cartridge achieves high-precision imaging within a confined space. Furthermore, a motion detection device provides signal feedback to further improve printing accuracy and quality. Feedback signals are used for correction, reducing errors caused by missed steps from the stepper motor. By converting linear motion into rotational motion and detecting the rotational motion, linear motion errors are determined, reducing the production cost of the detection system and saving space in the entire printing assembly. The motion trajectory of the ink cartridge component is planned using trapezoidal or triangular velocity curves; the velocity curve type is automatically selected based on the travel distance to achieve smooth acceleration, constant speed, and deceleration. The deviation between the desired and actual positions is calculated in each control cycle; if the deviation exceeds a preset threshold, it is considered a missed step; the number of compensation pulses is calculated based on the deviation value, and compensation is performed by inserting pulses or adjusting the pulse frequency to ensure the positional accuracy of the ink cartridge component. An incremental PID control algorithm is used for closed-loop control of the ink cartridge component's position; sub-pixel-level positioning accuracy is achieved through comprehensive adjustment of proportional, integral, and derivative terms. Attached Figure Description

[0021] Appendix Figure 1 This is a schematic diagram of the overall structure of this embodiment; Appendix Figure 2 This is an exploded structural diagram of this embodiment; Appendix Figure 3 A schematic diagram of the ink cartridge moving components and ink cartridge structure; Appendix Figure 4A schematic diagram of the overall structure of the ink cartridge moving assembly; Appendix Figure 5 A schematic diagram of the exploded structure of the ink cartridge moving components; Appendix Figure 6 A three-dimensional structural diagram of the ink cartridge motion assembly and detection assembly; Appendix Figure 7 for Figure 6 A side view diagram; Appendix Figure 8 This is a schematic diagram illustrating the printing and error correction principles of this embodiment; Appendix Figure 9 A three-dimensional diagram of the roll structure viewed from below; Appendix Figure 10 A top-view 3D schematic diagram of the paper roll structure; Appendix Figure 11 Main control system module diagram; Appendix Figure 12 This is a system workflow diagram; Explanation of reference numerals in the attached diagram: 1 is the bracket, 101 is the side baffle, 102 is the base plate, 103 is the U-shaped groove, 2 is the paper roll structure, 201 is the paper roll wheel, 202 is the paper roll motor, 203 is the synchronous belt, 204 is the fastener, 205 is the gear set, 3 is the lead screw, 4 is the ink cartridge motion assembly, 401 is the ink cartridge holder, 402 is the mounting position, 403 is the through hole, 404 is the lead screw nut, 405 is the ink cartridge, 406 is the fixing plate, 5 is the motion detection device, 501 is the rack, 502 is the gear assembly, 503 is the detection circuit board, 504 is the rotating shaft, 505 is the sensor mounting part, 506 is the gear, 7 is the lead screw drive motor, 8 is the bearing, 9 is the stabilizing support rod, 10 is the cross plate, and 1001 is the sensing assembly. Detailed Implementation

[0022] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0023] For ease of understanding, the present invention will now be described in further detail with reference to specific implementation examples, but this is not intended to limit the present invention.

[0024] In this embodiment, based on the characteristics of existing technology, inkjet printing is chosen to project the electronic pattern onto paper. The advantages of inkjet printing are: 1. The relevant technical solutions for inkjet printing are relatively mature, and the production cost of components is low. 2. Inkjet printing offers high pixel quality, achieving approximately 17 megapixels on a 6-inch photograph. 3. Inkjet printing consumables are cheaper; the price of ink is far lower than that of dye-sublimation solid dyes, and ordinary paper can be used for imaging, resulting in relatively low operating costs.

[0025] Based on the above characteristics, the applicant designed this inkjet printing device and placed it inside the camera housing to achieve the printing imaging function.

[0026] Example: Reference Figure 1 It includes the following main parts: bracket 1, paper roll structure 2, ink cartridge motion assembly 4, lead screw 3 and motion detection device 5.

[0027] In existing inkjet printers, the movement of the ink cartridge is primarily driven by gears and toothed belts. The gears drive the belt, which in turn pulls the ink cartridge in a reciprocating motion, ejecting ink onto the printing paper to create an image. The reason existing inkjet printers use gear drives is their high stability and resistance to slippage. However, this drive method has another drawback: lower precision. Because the gear and belt are driven by single teeth, each movement requires at least one tooth pitch, sacrificing some precision. Furthermore, over time, the belt ages and becomes prone to loosening and slippage. Because existing inkjet printers are relatively large with a large lateral travel, the impact of tooth pitch is relatively small. However, in handheld printing cameras, the camera's smaller size makes this gear-driven method unsuitable. The limited internal volume results in a shorter ink cartridge travel distance. With this shorter travel distance, the remaining tooth pitch (travel precision is determined by the travel distance and the number of teeth; the shorter the travel distance, the greater the impact of tooth pitch) leads to extremely poor image quality. If the tooth spacing is too small or the tooth size is reduced, the meshing ability of the teeth will inevitably decrease, making it very easy for the belt to slip.

[0028] Therefore, in this embodiment, a lead screw 3 is used for driving, thereby solving the problem of tooth pitch.

[0029] like Figure 1 , Figure 2 As shown, the bracket 1 has a U-shaped structure. The lead screw 3 is mounted on both sides of the side baffles 101 on both sides of the bracket 1. A U-shaped groove 103 is provided at the position where the lead screw 3 is placed on the side baffle 101. The lead screw 3 passes through the bearing 8, and the bearing 8 is engaged and secured within the U-shaped groove 103, thus fixing the lead screw 3. One end of the lead screw 3 is fixedly locked to the lead screw drive motor 7 (various methods can be used for fixing, the most common being a pin-key connection, but a snap-fit ​​connection is also possible). In this embodiment, the lead screw drive motor 7 is a stepper motor. Because stepper motors have high control precision, low cost, and low speed with high torque, they are particularly suitable for driving lead screws and for placement in small spaces.

[0030] The ink cartridge moving assembly 4 includes an ink cartridge holder 401, a mounting position 402, two through holes 403, and an ink cartridge 405. The ink cartridge holder 401 is used to hold the ink cartridge 405, and the ink cartridge 405 has a size of 42. twenty four The 18mm miniature ink cartridge is designed to fit within the internal space of the camera housing. A magnet is located at the bottom of the cartridge 405, and a corresponding magnet with opposite polarity is located at the bottom of the cartridge holder 401, allowing them to be fixed together by attraction. The bottom of the cartridge holder 401 also features a flexible pin, which is electrically connected to the metal contact point at the bottom of the cartridge 405. Simultaneously, the flexible pin is electrically connected to the detection circuit board 503 via a flexible conductive wire.

[0031] (refer to Figure 3 Mounting position 402 is used to mount motion detection device 5. Two through holes 403 are located between mounting position 402 and ink cartridge holder 401, respectively for engaging with stabilizing support rod 9 and lead screw 3. One through hole 403 houses lead screw nut 404 for engagement with the lead screw. Thus, when lead screw 3 rotates, it drives lead screw nut 404 to reciprocate. Because the lead screw has a circular structure, a single through hole 403 is insufficient to form a stable support structure, so stabilizing support rod 9 is added. The other through hole 403 passes through stabilizing support rod 9, thereby stabilizing the ink cartridge motion assembly 4. The basic operating principle of lead screw 3 is that its surface has spiral recesses or protrusions, which engage with the corresponding spiral patterns inside lead screw nut 404. When lead screw 3 rotates, it drives lead screw nut 404 to move linearly. Compared to existing inkjet printing technology that relies on teeth for engagement, this method significantly improves accuracy (eliminating the constraint of tooth spacing), making it very suitable for small printing cameras. Furthermore, the imaging technology solutions for inkjet printing and travel position are existing and commonly used techniques, and the purpose of this invention is not to improve inkjet imaging technology, so they will not be described in detail here.

[0032] The motion technology solutions for lead screw 3 and lead screw nut 404 are existing mature technologies and will not be described in detail here.

[0033] Stepper motors offer high precision, but they also have a drawback: the issue of missed steps. Each step of a stepper motor's movement is driven by an external pulse command. Normally, each pulse command drives the stepper motor to rotate once, with the rotation time and angle constrained by the pulse command. However, environmental factors such as excessive load, excessive acceleration, and signal interference can cause missed steps. A small number of missed steps have little impact on image quality. But when a large number of missed steps occur and accumulate, it leads to inaccurate rotation of the lead screw 3, which in turn causes inaccurate positioning of the ink cartridge movement assembly 4, resulting in image quality problems.

[0034] Therefore, in this implementation, given the introduction of lead screw-driven printing technology, the problem of missing steps needs to be solved to ensure the highest possible printing accuracy. To address this, a motion detection device 5 was designed to determine whether a step-loss problem has occurred, thereby achieving closed-loop motion control and negative feedback.

[0035] To monitor step loss issues, especially on large CNC machines, large and high-precision detection equipment such as grating rulers are generally used to monitor the movement position of moving components in real time. This technique achieves excellent real-time monitoring. The principle is to use the difference between the number of rotations of the lead screw 3 and the linear movement distance of the lead screw nut 404 for judgment. If the two are consistent, it indicates no step loss has occurred. If the actual movement distance of the lead screw nut 404 is less than the calculated theoretical distance, the system determines that a step loss has occurred. Based on the difference, the distance to be corrected is calculated, and a compensation command is sent to the stepper motor to accelerate or increase the rotation of the lead screw 3, thereby pushing the lead screw nut 404 to the correct position. Repeating this operation reduces the impact of step loss. However, such grating rulers are expensive, bulky, and consume a lot of power, making them unsuitable for the handheld camera device in this embodiment.

[0036] In this embodiment, since the final product is a consumer-grade children's printing camera, it is definitely inappropriate to use the above-mentioned technical means for monitoring. They are unsuitable in terms of cost and space.

[0037] Therefore, this invention employs a self-developed detection technology solution to achieve the same objective. The technical means of this invention is to use the cooperation of a rack and pinion 501 and a gear assembly 502 to convert between "rotational motion" and "linear motion," thereby solving the problem of missed steps. This also simplifies the size and cost of the detection device.

[0038] refer to Figure 4 5, 6, 7. The motion detection device 5 includes a rack 501, a gear assembly 502, and a detection circuit board 503. The rack 501 and the lead screw 3 are arranged in parallel and mounted on the side baffle 101. The gear assembly 502 is mounted on the cartridge motion assembly 4, and the rack 501 and the gear assembly 502 mesh with each other. The detection circuit board 503 is mounted on the cartridge motion assembly 4 and is used to detect the rotation state of the gear assembly 502.

[0039] The key design feature of this invention is the recessed mounting position 402 on the side of the ink cartridge moving assembly 4 near the lead screw 3. The gear assembly 502 is housed within this recessed mounting position 402, significantly reducing the component's size. Furthermore, since the ink cartridge moving assembly 4 is the final result of the movement, accurate data acquisition is achieved. The recessed mounting position 402 has fixing plates 406 at both its upper and lower ends, ensuring stable mounting of the gear 506. These fixing plates, in conjunction with the rotating shaft 504, form a stable I-beam structure, maintaining stability even when the rack 501 and gear assembly 502 are subjected to unexpected impacts or conventional compressive forces. Simultaneously, the design of keeping the detection circuit board 503 and sensor mounting part 505 away from the gear 506 and rack 501 reduces interference and damage to these two important and sensitive electronic components caused by dust and dirt generated during movement.

[0040] refer to Figure 5 The gear assembly 502 includes a gear 506, a rotating shaft 504, a sensor mounting part 505, and two bearings 8. The two bearings 8 are respectively disposed at the upper and lower ends of the rotating shaft 504. The gear 506 is mounted above the lower bearing 8. The two bearings 8 are respectively disposed in the through holes of the fixing plate 406, and the rotating shaft 504 is perpendicular to the rack 501. The gear 506 is located between the fixing plates 406, near the lower end, and meshes with the rack 501. The sensor mounting part 505 is located at the top of the rotating shaft 504 and is exposed on the upper fixing plate 406. The sensor mounting part 505 and the gear 506 rotate synchronously. There are various ways to install the sensor mounting part 505. In this embodiment, the sensor mounting part 505 is placed at the top of the rotating shaft 504. Combined with the I-shaped structure, reliable and stable detection results are achieved. Placing the sensor directly on gear 506 would make its manufacturing extremely difficult, increasing costs. Furthermore, deformation of gear 506 could lead to deviations during meshing with rack 501, shortening its lifespan. Additionally, the lack of an I-beam structure for support would cause skewness, resulting in inaccurate detection results.

[0041] The separate design of the sensor mounting section 505 expands the application scenarios, allowing for the installation of different sensors as needed and facilitating maintenance and replacement. This significantly reduces production and maintenance costs.

[0042] There are many methods for detecting the angle and number of rotations, and the corresponding methods are explained here.

[0043] The first approach uses an angular momentum sensor. The angular momentum sensor is soldered to the side of the detection circuit board 503 facing the sensor mounting part 505. The sensor mounting part 505 and the angular momentum sensor are connected as a single unit using a snap-fit ​​or pin method. When the sensor mounting part 505 rotates, it drives the angular momentum sensor to rotate, thereby obtaining the rotation angle signal and achieving the monitoring purpose. This approach offers relatively accurate monitoring and can detect variables at each angle.

[0044] In the second technical solution, the magnetic induction sensor is a magnetic induction chip, specifically the VCE2758Q chip manufactured by MicroTrans Intelligent Technology (Changzhou) Co., Ltd. This chip is based on anisotropic magnetoresistive (AMR) technology and is used for 14-bit resolution 360° magnetic field angle detection. Correspondingly, magnets (radially magnetized cylindrical magnets) with symmetrically arranged N and S magnetic poles are mounted on the sensor mounting part 505, with the magnets and the magnetic induction chip's center coinciding. This technical solution utilizes the change in magnetic field generated by the rotation of the magnet to cause a change in electrical signal in the magnetic induction chip, sensing the rotation angle of the gear 506, thereby detecting the movement position of the ink cartridge moving assembly 4. This technical solution is also a non-contact solution and is the technical solution adopted in this embodiment.

[0045] The above design and technical solution provides a more precise monitoring structure, enabling real-time linear small-angle rotation monitoring, which is reflected in the straight-line distance. It can monitor and provide feedback on minute distances with higher accuracy.

[0046] The above technical solutions are all for detecting and providing feedback on the number of rotations of the sensor mounting part 505.

[0047] The accuracy demonstrated in this embodiment is as follows: Eliminating backlash and enhancing rigidity: Screw drives involve continuous helical surface contact, eliminating backlash issues and resulting in significantly higher transmission rigidity and precision compared to belt drives. This fundamentally eliminates hysteresis errors during reversal, ensuring the accuracy of the starting point and direction of motion.

[0048] Nanoscale equivalent feedback accuracy: Assuming the gear pitch circle diameter is 10mm, its circumference is approximately 31.4mm.

[0049] Using a 14-bit resolution (16384 steps) magnetic induction chip to monitor gear rotation means the system can divide a 31.4mm circumference into 16384 detectable steps. Therefore, the feedback resolution for linear displacement = 31.4mm / 16384 ≈ 0.00192mm (1.92 micrometers). This is equivalent to the system being able to detect displacement changes of approximately 2 micrometers in the direction of cartridge movement, demonstrating extremely high feedback accuracy.

[0050] The following section explains the various related systems and their working principles: To improve printing accuracy and stability under this new design, a more suitable main control system and its control system are adopted, thereby achieving reliable printing results.

[0051] Example of Control and Feedback Method of Main Control System like Figure 11 As shown, the main control system in this embodiment includes the following core modules: Main control chip: Uses a 32-bit ARM Cortex-M series microcontroller (such as STM32F407), with built-in: multiple timers (TIM1-TIM8) for generating stepper motor pulses and acquiring encoder signals.

[0052] The ADC module is used to monitor power supply voltage and motor current.

[0053] The SPI interface connects to the magnetic induction chip (VCE2758Q).

[0054] The GPIO port controls inkjet triggering, limit switches, motor enable, etc. The internal Flash memory stores the printing firmware and font library.

[0055] Motor drive module: Uses a dual H-bridge driver chip (such as DRV8833) to drive the stepper motor, and integrates current detection and overcurrent protection circuits.

[0056] Power management module (existing technology is widely available, and small handheld devices such as cameras and mobile phones have it): powered by lithium battery (3.7V), providing 3.3V and 5V through DC-DC conversion, with low battery detection and sleep function.

[0057] Storage module: External SPI Flash (16MB) for storing images to be printed; SD card interface for supporting expanded storage.

[0058] User interface: key input, LED status indicator, buzzer prompt.

[0059] The workflow of this embodiment is as follows: Figure 12 As shown, In this embodiment, the lead screw drive motor 7 is a stepper motor. Stepper motors have good start-stop function, strong self-locking ability, large torque, and small size, making them very suitable for the application in this embodiment. Because portable devices inevitably experience significant vibrations, a motor with strong self-locking ability is required.

[0060] The methods for controlling the motion stability of ink cartridges are as follows: In this embodiment, the system employs a motion trajectory planning algorithm based on a trapezoidal velocity curve to control the smooth acceleration, constant speed, and deceleration of the ink cartridge motion components during the printing process. This improves printing efficiency while preventing a decrease in printing accuracy due to motor step loss or overshoot.

[0061] The system defines a data structure to describe the complete motion process, which includes the following key parameters: Current position: The instantaneous position of the moving component, expressed as the number of control pulses received by the drive motor.

[0062] Target position: The expected endpoint position of this motion, expressed in pulse count.

[0063] Acceleration: A parameter that indicates how fast a moving component increases its speed, measured in pulses per square second.

[0064] Maximum speed: The highest speed that can be achieved in this exercise, measured in pulses per second.

[0065] Deceleration point: A pre-calculated position point that indicates from which the moving component should transition from a constant speed or acceleration state to a deceleration phase.

[0066] Trapezoidal velocity curve planning algorithm flow The system uses a motion trajectory calculation function to automatically plan the optimal motion velocity curve based on the above parameters. The execution steps of the algorithm are as follows: Step 1: Calculate the theoretical acceleration distance First, based on the set maximum speed and acceleration, the theoretical number of pulses (i.e., acceleration distance) required for the moving component to accelerate from rest to the maximum speed is calculated. The calculation formula is: acceleration distance equals the square of the maximum speed divided by twice the acceleration.

[0067] Step 2: Calculate the total distance traveled Calculate the absolute value from the current position to the target position to obtain the total number of pulses (i.e., the total movement distance) required for this movement.

[0068] Step 3: Determine the shape of the motion curve and calculate the deceleration point. Based on the relationship between the total distance traveled and the theoretical acceleration distance, the system automatically determines and generates two optimal motion curves: 1. Triangular velocity curve (suitable for short-distance sports): When the total travel distance is less than twice the theoretical acceleration distance, it indicates that the travel distance is too short to maintain a constant speed after accelerating to the maximum speed. In this case, the system adopts a triangular velocity curve without a constant speed segment. Its deceleration point is set at the midpoint of the total travel distance, meaning that the moving components will begin to decelerate immediately upon reaching the midpoint.

[0069] 2. Trapezoidal velocity curve (suitable for medium to long distance sports): When the total travel distance is greater than or equal to twice the theoretical acceleration distance, it indicates that the travel distance is sufficient. At this time, the system adopts a trapezoidal velocity curve that includes an acceleration phase, a constant speed phase, and a deceleration phase. The deceleration point is set as the total travel distance minus the theoretical acceleration distance, thereby ensuring that the moving components have sufficient distance to smoothly decelerate from maximum speed to a standstill.

[0070] The motion trajectory planning method described in this embodiment achieves the following beneficial effects: Smooth motion: Avoids the impact on mechanical structures caused by sudden speed changes, improving the stability and lifespan of equipment operation.

[0071] Printing accuracy assurance: By preventing the stepper motor from losing steps during high-speed start-up or stop, the positioning accuracy of the ink cartridge at each predetermined position is ensured, fundamentally guaranteeing the quality of printed images.

[0072] Adaptive planning: The algorithm can automatically select the optimal speed curve (triangle or trapezoid) according to different travel distances, maximizing motion efficiency while ensuring accuracy. It is particularly suitable for the compact internal space and variable travel characteristics of handheld printing cameras.

[0073] Methods for controlling the precise position of motor-driven ink cartridges: The system employs an incremental PID (proportional-integral-derivative) control algorithm with anti-saturation and output limiting to achieve precise real-time control of the position of the ink cartridge moving components. This control method effectively suppresses system overshoot, eliminates steady-state error, and ensures control stability under external disturbances.

[0074] 1. Controller parameters and state structure The system defines a controller data structure to store the parameters and operating status of the PID algorithm. This structure contains the following six key elements: Proportional coefficient: A floating-point value used to determine the strength of the controller's response to the current error. The proportional term directly affects the system's response speed.

[0075] Integral coefficient: A floating-point value used to determine the strength of the controller's response to accumulated historical errors. The integral term is used to eliminate the system's steady-state error.

[0076] Differential coefficients: floating-point values ​​used to determine the strength of the controller's response to trends in error. Differential terms help suppress system overshoot and improve stability.

[0077] Previous error: A floating-point value that records the error value calculated in the previous control cycle and is used to calculate the error change rate (differential term).

[0078] Integral term: A floating-point value that accumulates the weighted sum of historical errors and is used to achieve integral control.

[0079] Output limit value: A floating-point value that defines the upper and lower absolute values ​​of the controller's output signal to prevent the control quantity from exceeding the effective working range of the actuator.

[0080] 2. PID control quantity calculation process The system periodically executes the following steps through a control quantity calculation function: based on the target position (setpoint) and actual position feedback, it calculates and outputs control quantities (such as motor pulse frequency adjustment): Step 1: Calculate the current control error Subtracting the actual measured value from the system feedback from the target setpoint value yields the error value for the current control cycle. This error value reflects the deviation between the current system state and the desired state.

[0081] Step 2: Calculate the proportional term and output it. Multiplying the current error value by the proportional coefficient yields the output of the proportional control term. The proportional term provides basic control action proportional to the error.

[0082] Step 3: Calculate the integral term output (including anti-saturation processing) 1. Error Accumulation: The current error value is added to the integral term.

[0083] 2. Anti-saturation limiting: To prevent the integral term from accumulating infinitely and causing "integral saturation" when large errors persist, the system limits the integral term. Specifically: if the value of the integral term exceeds a preset output limit, it is limited to that limit; if it is lower than a negative output limit, it is limited to that negative limit. This anti-saturation mechanism ensures that the system can quickly recover its response when it escapes saturation.

[0084] 3. Integral Output Calculation: Multiply the limited integral term by the integral coefficient to obtain the output of the integral control term. The integral term is used to eliminate the static error of the system.

[0085] Step 4: Calculate the differential term output 1. Error Difference: Calculates the difference between the current error value and the previously recorded error value. This difference reflects the rate of change of the error.

[0086] 2. Differential Output Calculation: Multiply the rate of change of error by the differential coefficient to obtain the output of the differential control term. The differential term provides anticipatory regulation, which helps to suppress system oscillations.

[0087] 3. Error Update: Store the current error value as the "previous error" to prepare for the calculation of the next control cycle.

[0088] Step 5: Synthesize Control Output The calculated proportional, integral, and derivative outputs are added together to obtain the preliminary composite control output.

[0089] Step Six: Control Output Limiting The synthesized control output is subjected to final limiting processing to ensure that its value does not exceed the preset output limit range. If it exceeds the upper limit, the upper limit value is output; if it is below the lower limit, the lower limit value is output. This limiting value ensures that the output signal is within the effective input range of the actuator (such as a motor driver).

[0090] Step 7: Return to control quantity The final control output, after being limited, is returned to adjust the actuator and drive the system to move in the direction that reduces the error.

[0091] 3. Technical Effects and Advantages The PID control method described in this embodiment achieves the following beneficial effects: High-precision positioning: Combining the comprehensive adjustment of proportional, integral and derivative terms, it can quickly respond to and accurately correct position deviations, achieving sub-pixel-level positioning accuracy of the ink cartridge motion components.

[0092] Dynamic stability: The introduction of the differential term effectively predicts the error change trend, significantly reduces system overshoot and oscillation, and makes the motion process smoother, which is especially suitable for printing scenarios with high-speed reciprocating motion.

[0093] Anti-integral saturation: By intelligently limiting the integral term, the "integral saturation" problem that occurs in traditional PID control when errors exist for a long time is avoided, ensuring that the system remains stable and controllable during startup, commutation or when encountering obstacles.

[0094] Parameter adaptability: The proportional, integral, and derivative coefficients can be independently adjusted according to specific mechanical loads and motion characteristics, enabling the same control algorithm to adapt to differences in different models or batches of products, thereby enhancing the robustness of the system and production consistency.

[0095] The working principle of motion detection device 5 will be further explained below: The main control system sends a drive pulse signal command to drive the lead screw drive motor 7 to rotate. For example, when the initial position sensor mounting part 505 and the detection circuit board 503 are in the recognition state, assuming 10 pulse signals drive the lead screw drive motor 7, thereby causing the lead screw 3 to rotate 10 revolutions. With the lead screw 3 rotating 10 revolutions, the gear 506 rotates 1 revolution under the constraint of the rack 501, thus determining that the distance the cartridge motion assembly 4 travels in a straight line is 2πR (the radius of the gear 506). The magnetic induction chip can detect that the angle of rotation of the sensing gear 506 is exactly 360 degrees. (Reference) Figure 8 (Above) Assuming the above straight-line distance is divided into 1-10 intervals, a total of 10 intervals were run. Simultaneously, the main control system sends commands to the ink cartridge, ensuring the correct pattern is printed at each corresponding position. Starting from the initial position, if no steps are missed, the ink cartridge movement component 4 should be exactly at position 10. The sensor mounting unit 505 detects that the sensing gear 506 has rotated 360 degrees and feeds the signal back to the main control system. The main control system confirms that no steps have been missed and that the ink patterns formed at all positions are correct. It then continues to send the next batch of pulse signals to drive the lead screw 3 to rotate and perform other related actions such as printing ink patterns.

[0096] The above examples illustrate the principle of the sensor gear 506 rotating one revolution. Based on this understanding, further subdivisions can be made, such as providing data feedback or real-time feedback at 20 degrees or 10 degrees, to offer a higher correction effect and thus higher print quality.

[0097] (refer to Figure 8(Below) If a step loss occurs midway, and at any position from 1 to 10, assuming a pulse signal is lost, although the system sends 10 pulse signals, the ink cartridge movement component 4 is actually located at position 9 (because of the signal loss, it cannot reach the correct position 10). This results in the ink cartridge forming an incorrect pattern, leading to accumulated errors. Only under the drive of the 11th pulse signal can the ink cartridge movement component 4 reach position 10, but the ink cartridge will print the pattern at position 11 instead of position 10. The sensor on the sensor mounting unit 505 sends the rotation angle data to the main control system. After receiving the signal, the main control system compares the data and finds a step loss problem. This indicates that the pattern formed by the ink cartridge has an error. Without a feedback mechanism, the 12th pulse signal will be received normally, and the ink will be printed to form the pattern at position 12, resulting in accumulated quality problems. However, when the main control system receives the signal from the sensor on the sensor mounting unit 505, it will perform correction compensation. Although it will continue to send pulse signals to drive the ink cartridge forward, it will instruct it to generate an image at position 11 instead of position 12. This achieves the compensation effect, preventing the accumulation of errors and mistakes that could cause pattern distortion.

[0098] In this embodiment, a self-developed supplementary method is used. The specific compensation method is as follows: by establishing a real-time deviation monitoring mechanism between the desired position and the actual position, combined with a preset threshold criterion and an adaptive compensation algorithm, rapid detection and automatic correction of step loss phenomena that may occur during the operation of the stepper motor are achieved.

[0099] I. Data Monitoring Structure The system has established a dedicated data structure for out-of-step monitoring, which includes the following four core parameters: Desired position parameters: The theoretical position value calculated based on the total number of control pulses sent by the main controller to the stepper motor driver. It is stored in the form of a 32-bit signed integer, and its unit corresponds to the number of motor control pulses. Actual position parameters: Physical position measurements collected and fed back in real time by position sensors set on the ink cartridge motion assembly, using the same data format as the desired position parameters; Cumulative error parameter: The instantaneous position deviation calculated in each control cycle is continuously recorded and accumulated to form a historical error data sequence, which is used to analyze the error change trend and system stability; Error threshold parameter: A preset positive integer criterion value, which serves as the critical boundary for distinguishing normal position fluctuations from actual step loss events. This threshold can be dynamically configured according to specific motion accuracy requirements and system mechanical characteristics.

[0100] II. Step Loss Detection and Compensation Process The system achieves closed-loop control of motion step loss through periodic monitoring and compensation cycles. The specific execution process includes the following six steps: Step 1: Instantaneous Deviation Calculation Within each preset control cycle, the system performs a subtraction operation between the desired position parameter and the actual position parameter to calculate the position deviation value at the current moment. This calculation uses fixed-point arithmetic to ensure accurate results with limited processing resources.

[0101] Step 2: Cumulative Error Update The calculated instantaneous position deviation value is added to the cumulative error parameter. The cumulative error parameter not only reflects the current deviation but also records the historical deviation accumulation during system operation, providing a data foundation for subsequent system stability analysis and predictive maintenance.

[0102] Step 3: Logic for determining if a step is lost The system compares the absolute value of the instantaneous position deviation with a preset error threshold parameter and executes the corresponding control branch based on the comparison result: No loss of synchronization: When the absolute value of the instantaneous position deviation is less than or equal to the error threshold parameter, the system determines that no loss of synchronization event requiring intervention has occurred, and skips the compensation process to directly enter the next control cycle; Loss of synchronization: When the absolute value of the instantaneous position deviation is greater than the error threshold parameter, the system determines that a valid loss of synchronization event has occurred and then starts the automatic compensation mechanism.

[0103] Step 4: Compensation Amount Calculation Algorithm After confirming the out-of-step event, the system calculates the required compensation control quantity according to the following algorithm: 1. Obtain the preset compensation ratio coefficient, which has been optimized through system calibration experiments; 2. Multiply the instantaneous position deviation value by the compensation ratio coefficient to obtain the theoretical number of compensation pulses; 3. Perform numerical range verification and rounding on the calculation results to ensure the validity and feasibility of the compensation amount.

[0104] Step 5: Dynamic Compensation Execution Mechanism After the compensation calculation is completed, the system achieves dynamic correction through the following two parallel operations: 5.1 Control Signal Adjustment The pulse frequency modulation function is invoked to convert the calculated number of compensation pulses into adjustment parameters for the timing of subsequent control pulses. This adjustment can be performed using one or a combination of the following two methods: Pulse insertion method: Inserting extra pulses into the original pulse sequence to make up for the missing motion distance; Frequency modulation method: Temporarily increase the transmission frequency of subsequent pulses to accelerate the pursuit to the target position.

[0105] 5.2 Internal State Synchronization To avoid introducing new reference deviations during compensation operations, the system synchronously updates the internally maintained desired position parameters, increasing their values ​​by an amount equal to the number of compensation pulses, ensuring that the desired position calculation in subsequent control cycles remains synchronized with the current actual motion state.

[0106] Step Six: Status Feedback and Recording (Optional) After the compensation is completed, the system returns a status flag to the main control module indicating that a step loss event has occurred and compensation has been completed. Simultaneously, the key parameters of this step loss event (including occurrence time, deviation, compensation amount, etc.) are recorded in non-volatile memory to form a device operation history log for subsequent analysis.

[0107] III. Technological Advantages and Innovation Effects The out-of-step detection and compensation method provided in this embodiment has the following significant advantages compared to traditional open-loop control schemes: Real-time correction capability By executing a complete detection-calculation-compensation cycle once in each control cycle (typically 100 microseconds to 1 millisecond), the system can respond to and correct the stepper motor's step loss phenomenon in real time, keeping the position error within the range that can be corrected with a single compensation, and avoiding the cumulative propagation of errors.

[0108] Adaptive compensation strategy The calculation of the compensation amount not only considers the magnitude of the current deviation, but can also be dynamically adjusted according to the system's operating status. Specifically: Different compensation ratio coefficients are set for different speed ranges; The error threshold parameter is adaptively adjusted based on the historical frequency of step loss and the trend of deviation. In the event of repeated loss of synchronization, the compensation intensity should be gradually increased to ensure the corrective effect.

[0109] System robustness enhancement This method significantly improves the drive system's tolerance to the following abnormal operating conditions: Sudden load change: When the ink cartridge encounters a sudden increase in mechanical resistance during movement, the system can quickly detect and compensate for the resulting loss of synchronization. Voltage fluctuations: This method can compensate for changes in motor torque caused by power supply voltage fluctuations. Mechanical wear: Increased clearance in transmission components due to long-term use can be offset by adjusting compensation parameters.

[0110] Predictive maintenance support The cumulative error parameters and out-of-step event logs recorded by the system provide a data foundation for predictive maintenance of the equipment. When the cumulative error parameter shows a continuous increasing trend, it indicates that the system may have mechanical wear or insufficient lubrication. An abnormally high frequency of out-of-synchronization events can provide early warning of potential drive system failures; Analysis based on historical data can provide a quantitative basis for maintenance decisions.

[0111] Functional verification conducted on a handheld printing camera prototype equipped with the method described in this embodiment showed that: at normal printing speed, the ink cartridge positioning accuracy improved from ±3 pixels to ±0.5 pixels; in simulated interference tests (applying additional vibration and resistance), the system was able to maintain a printing pass rate of over 95%; and after 100 hours of continuous operation, the cumulative position error growth did not exceed 10% of the initial error, which is significantly better than traditional open-loop control schemes.

[0112] This method provides a reliable position control solution for miniaturized, high-precision printing equipment through a real-time monitoring and adaptive compensation mechanism that combines hardware and software, extending the equipment's lifespan and maintenance cycle while ensuring print quality. Of course, the above method is the one used in this embodiment, but there are other corresponding methods: for example, the multi-level threshold criterion method, which uses multiple progressive error threshold parameters to achieve a graded response mechanism. The initial level triggers an early warning record but does not immediately compensate. The intermediate level triggers mild compensation measures, and the severe level triggers strong compensation and may be accompanied by accelerated operation. Actual test comparison: Test method: Print a fine diagonal line with a width of 1 pixel and a 45-degree angle to the horizontal.

[0113] Testing tool: Laser angle measuring instrument Number of measurements: 10 consecutive sheets of printing paper Test results: Existing belt-driven technology: The lines are "stepped" and not smooth enough. Furthermore, the overall lines exhibit angular differences (maximum deviation of 0.3 degrees), and there are slight bends at the edges. The more paper printed, the more obvious the defects become.

[0114] In the technical solution of the embodiment: the lines are smooth, continuous, and straight. Furthermore, the overall lines exhibit an angular difference (maximum deviation of 0.1 degrees), and are smooth at the edges.

[0115] In this embodiment, a horizontal plate 10 is also provided above the rack 503. Two sensing components 1001 are provided on both sides of the horizontal plate 10 as the starting position of the ink cartridge moving component 4. The sensing components 1001 contain infrared emitting tubes and receiving tubes respectively. When the detection circuit board 503 moves to this position, the infrared receiving tube receives the reflected infrared signal after the protrusion of the detection circuit board 503 forms a blockage, indicating that the ink cartridge moving component 4 has moved to the starting position and needs to stop or change the direction of movement.

[0116] refer to Figure 9 10. A paper winding structure 2 is provided on the base plate 102 below the support 1. The paper winding structure 2 includes two paper winding wheels 201, a fastening member 204, a synchronous belt 203, a paper winding motor 202, and a bearing 8. The two paper winding wheels 201 pass through the bearing 8 and are fixed to the base plate 102 with screws in conjunction with the fastening member 204. The paper winding wheels 201 are meshed with each other by the synchronous belt 203. The shaft of one of the paper winding wheels 201 passes through a gear set 205, and the gear set 205 is fixed to the side baffle 101 by a rotating shaft. The paper winding motor 202 drives the gear set 205, thereby driving the paper winding wheel 201 to perform the paper winding action.

[0117] The base plate 102 has mounting holes for fixing with screws and the camera housing (the camera housing is not shown).

[0118] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the inventive concept, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A hand-held high-precision inkjet printing device, characterized by: The support comprises a U-shaped structure, two side plates are formed on the two sides, a screw rod is arranged between the two side plates, the screw rod is driven by a screw rod driving motor, the ink cartridge movement assembly comprises an ink cartridge seat and a screw rod nut, the screw rod nut is matched with the screw rod, and the ink cartridge movement assembly moves along the screw rod in a reciprocating linear manner, the movement detection device is used for detecting the movement position of the ink cartridge movement assembly, closed-loop control is realized, and a paper winding structure is arranged at the bottom of the support and used for conveying the printing paper.

2. The handheld high precision inkjet printing device of claim 1, wherein: The movement detection device comprises a rack, a gear assembly and a detection circuit board, the rack and the screw rod are arranged in parallel, the rack is arranged on the side plate, the gear assembly is arranged on the ink cartridge movement assembly, the rack and the gear assembly are in meshing connection, and the detection circuit board is arranged on the ink cartridge movement assembly and used for detecting the rotation state of the gear assembly.

3. The handheld high precision inkjet printing device of claim 2, wherein: The gear assembly comprises a gear, a rotating shaft, a sensor mounting portion and a bearing, the rotating shaft is arranged on the ink cartridge movement assembly through the bearing, the gear and the sensor mounting portion are arranged at two ends of the rotating shaft respectively, the rotating shaft is arranged perpendicularly to the rack, the gear is in meshing connection with the rack, and a sensor signal emitting end is arranged on the sensor mounting portion.

4. The handheld high precision inkjet printing device of claim 3, wherein: A magnetic induction sensor is arranged on the detection circuit board, a magnet matched with the magnetic induction sensor is arranged on the sensor mounting portion, and the rotation angle of the gear is detected in a non-contact manner.

5. The handheld high precision inkjet printing device of claim 3, wherein: An angle sensor is arranged on the detection circuit board, the rotation angle is calculated, and the sensor mounting portion and the angle sensor are coupled.

6. The handheld high precision inkjet printing device of claim 3, wherein: A horizontal plate parallel to the rack is arranged above the rack, sensing assemblies are arranged at left and right ends of the horizontal plate, and the sensing assemblies are matched with the detection circuit board to identify the position of the ink cartridge movement assembly.

7. The handheld high precision inkjet printing device of claim 1, wherein: The ink cartridge movement assembly comprises an ink cartridge seat, a mounting position and two through holes, the ink cartridge seat is used for placing an ink cartridge, the ink cartridge is fixed on the ink cartridge seat in a magnetic attraction manner, the mounting position is an inner recess structure and is used for mounting the movement detection device, and the two through holes are respectively used for matching with a stable supporting rod and the screw rod, a screw rod nut is arranged in the through hole matched with the screw rod, and the screw rod driving motor is a stepping motor.

8. A control method for the handheld high-precision inkjet printing device according to any one of claims 1-7, characterized in that: The method comprises the following steps: S1, the main control system sends a pulse signal to the stepping motor to drive the screw rod (3) to rotate; S2, the movement detection device (5) detects the actual position of the ink cartridge movement assembly (4) in real time; S3, the actual position is compared with the expected position to determine whether step loss occurs; S4, if step loss occurs, the number of compensation pulses is calculated, and the subsequent pulse signal is adjusted to correct the position deviation.

9. The control method according to claim 8, characterized in that: Further comprising: A trapezoidal speed curve or a triangular speed curve is adopted to plan the movement trajectory of the ink cartridge movement assembly; the speed curve type is automatically selected according to the movement distance to realize smooth acceleration, constant speed and deceleration.

10. The control method according to claim 8, characterized in that: The step loss detection and compensation method comprises the following steps: the deviation between the expected position and the actual position is calculated in each control cycle; if the deviation exceeds a preset threshold value, it is determined that step loss occurs; the number of compensation pulses is calculated according to the deviation value, and compensation is performed by inserting pulses or adjusting the pulse frequency.

11. The control method according to claim 8, characterized by: Further comprising: An incremental PID control algorithm is adopted to perform closed-loop control on the position of the ink cartridge movement assembly; Through proportional, integral and differential comprehensive adjustment, sub-pixel level positioning accuracy is realized.

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