Pad printing method and system of cosmetic pupil VU line printing machine

Abstract

The invention provides a transfer printing method and system for a cosmetic contact lens VU line printing machine, and the method comprises the steps: cleaning a flat steel plate, directly printing a pattern matched with a to-be-printed area of a cosmetic contact lens on the surface of the steel plate in an ink-jet manner, recognizing the center position of the ink-jet pattern through an optical focusing device, and locking the coordinate, and controlling the rubber head to adsorb the ink and then transferring the ink to the surface of the cosmetic contact lens, and finally performing surface curing treatment on the cosmetic contact lens. The system comprises a plurality of function modules which cooperatively execute the method. The ink jet mode is adopted to replace a traditional laser etching machining steel plate, precise positioning is achieved through optical focusing, various pattern transfer printing of cosmetic contact lenses is adapted, and technical management and control of the whole transfer printing process are improved.

Description

Technical Field

[0001] This invention relates to the field of colored contact lens processing technology, specifically to a pad printing method and system for a colored contact lens VU printing machine. Background Technology

[0002] In the production of colored contact lenses, pad printing is the core process for printing patterns on the lens surface. Currently, the industry generally uses traditional pad printing technology to print patterns on contact lenses. This process requires first laser-engraving a steel plate to form pre-set patterned grooves on the surface. Then, ink is applied to the steel plate surface through an ink cup, filling the laser-engraved grooves. Finally, a glue head adheres to the steel plate surface, absorbs the ink from the grooves, and transfers it to the colored contact lens surface, completing the pad printing process. The core of this traditional process relies on the precision of the laser engraving on the steel plate. To ensure the subsequent ink absorption and transfer effect, strict control must be exercised over the flatness of the steel plate, the depth of the laser-engraved pattern, and the regularity of the outline. In particular, the positional accuracy of the laser-engraved pattern is extremely important, ensuring that the pattern position precisely corresponds to the glue head and the area to be printed on the colored contact lens.

[0003] Traditional laser-engraved steel plate pad printing technology has many shortcomings. The laser engraving process is complex, requiring specialized equipment and skilled operators, resulting in long processing times and significantly increasing processing costs. During laser engraving, the positional accuracy and contour precision of the pattern are easily affected by equipment precision and operator skill; deviations are irreparable and necessitate scrapping, further increasing production costs. Furthermore, for complex patterns, traditional laser engraving struggles to accurately reproduce details, often resulting in blurred edges and lost details. The lack of precise positioning methods leads to insufficient alignment between the printing head and the laser-engraved pattern, causing unstable printing dimensions and affecting the quality of contact lens products. In addition, the traditional process relies on manual control at each stage, resulting in low efficiency and difficulty adapting to the pad printing needs of mass-produced contact lenses with various patterns, failing to meet the industry's requirements for efficient, precise, and low-cost production. Summary of the Invention

[0004] To address the aforementioned technical shortcomings, the purpose of this invention is to provide a pad printing method and system for a VU printing machine for colored contact lenses, adaptable to pad printing of various colored contact lens patterns, and improving the technical control of the entire pad printing process.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A pad printing method for a colored contact lens VU printing machine includes the following steps:

[0007] S1. Prepare a flat steel plate and clean its surface;

[0008] S2. Printing patterns directly onto the surface of a flat steel plate using inkjet printing to form an inkjet pattern that matches the area to be printed on the contact lens.

[0009] S3. Focus and locate the inkjet pattern on the surface of the steel plate using an optical focusing device, identify the center position of the inkjet pattern and lock the coordinates.

[0010] S4. Control the glue head to move above the locked center position, adjust the distance between the glue head and the steel plate surface, so that the glue head is completely attached to the inkjet pattern and absorbs the ink in the pattern.

[0011] S5. Move the ink-adsorbing adhesive head to the designated position of the contact lens to be transferred, adjust the adhesive head pressure and contact time, and transfer the ink to the surface of the contact lens;

[0012] S6. Perform surface curing treatment on the transferred contact lenses to complete the contact lens transfer printing operation.

[0013] Preferably, in step S2, the pattern is directly printed on the flat steel plate surface using inkjet printing. The specific steps are as follows: using UV inkjet printing, selecting UV ink specifically for contact lens printing, and accurately spraying the ink onto the flat steel plate surface through the inkjet printhead according to the preset pattern trajectory and fixed spray pressure, controlling the ink droplet diameter to be consistent, forming an inkjet pattern with uniform thickness and regular edges, and controlling the pattern thickness within the preset range to ensure matching with the adhesive head's adsorption characteristics.

[0014] Preferably, in step S3, the inkjet pattern on the steel plate surface is focused and positioned by an optical focusing device. The specific steps are as follows: the optical focusing device emits high-frequency detection light, which is perpendicularly irradiated onto the inkjet pattern area on the steel plate surface. The light reflected from the pattern is received and high-definition imaging is performed. The image recognition algorithm is used to extract the contour and calculate the center point of the image to accurately identify the center position of the inkjet pattern. At the same time, the X-axis and Y-axis coordinate parameters of the center position are locked and transmitted to the control unit.

[0015] Preferably, in step S4, adjusting the distance between the inkjet head and the steel plate surface involves the following steps: After receiving the coordinate parameters transmitted by the optical focusing and positioning module, the control unit drives the inkjet head to move along the Z-axis. Based on the preset thickness parameters of the inkjet pattern, the distance between the inkjet head and the steel plate surface is adjusted to a preset fixed value. During the adjustment process, the distance between the inkjet head and the steel plate is detected in real time to ensure that the inkjet head is fully attached to the inkjet pattern without squeezing or damaging the pattern structure, thus ensuring the integrity of ink adsorption.

[0016] Preferably, in step S6, the transferred contact lens is subjected to surface curing treatment. The specific steps are as follows: the transferred contact lens is transferred to the curing station, and a UV curing lamp is used to irradiate the ink on the surface of the contact lens in a directional manner. The irradiation power, irradiation distance and irradiation time of the UV curing lamp are controlled to make the ink cure quickly. During the curing process, the position of the contact lens is kept fixed to avoid ink dripping or smudging, and to ensure that the cured ink is tightly bonded to the surface of the contact lens, without peeling or fading.

[0017] Preferably, in step S1, a flat steel plate is prepared and its surface is cleaned. The specific steps are as follows: Select a steel plate whose surface flatness meets the preset standard, first use a dust-free wiping cloth dipped in special cleaning agent to wipe the surface of the steel plate in the same direction to remove dust, oil and impurities from the surface, then send the steel plate into the drying station and dry it with constant temperature hot air. After drying, check the dryness of the steel plate surface to ensure that the steel plate surface is dry without cleaning agent residue, scratches and stains.

[0018] Preferably, in step S4, the control of the printing head to move above the locked center position is specifically achieved by: driving the printing head to move through a servo drive mechanism; the servo drive mechanism receives coordinate parameters transmitted by the control unit and precisely controls the printing head to move along the X and Y axes; during the movement, the printing head position is calibrated in real time to ensure that the center of the printing head is precisely aligned with the center of the inkjet pattern, and the alignment error is controlled within a preset range to ensure the accuracy of subsequent ink adsorption and transfer.

[0019] A pad printing system for a UV inkjet printing machine for colored contact lenses includes a steel plate pretreatment module, an inkjet printing module, an optical focusing and positioning module, a printing head transfer module, a colored contact lens positioning module, a curing module, and a control system module. The steel plate pretreatment module includes a cleaning unit and a drying unit. The cleaning unit wipes and cleans the flat steel plate, and the drying unit dries the cleaned steel plate at a constant temperature. The inkjet printing module includes a UV inkjet printhead, an ink supply unit, and a movement drive unit, used to print patterns on the steel plate surface according to preset parameters. The optical focusing and positioning module includes a light emission... The unit, imaging unit, and coordinate calculation unit are used to focus, center identify, and lock coordinates of the inkjet pattern; the ink transfer module includes an ink head, servo drive unit, and pressure adjustment unit, used to absorb ink and transfer it to the contact lens; the contact lens positioning module is used to fix the contact lens to be printed and accurately position the printing area; the curing module includes a UV curing lamp and a station transfer unit, used to cure the ink on the transferred contact lens; the control system module is electrically connected to each module, used to receive feedback signals from each module and send control commands to achieve precise and coordinated control of the entire pad printing process.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] By cleaning and drying the flat steel plate, impurities and residues on the surface are removed, ensuring the steel plate surface meets the requirements for inkjet printing. This provides a foundation for the subsequent forming quality of inkjet patterns, preventing impurities from affecting the adhesion between the pattern and the steel plate, while ensuring neat pattern edges and adapting to the precise printing of complex patterns. Inkjet printing directly onto the surface of the flat steel plate replaces traditional laser engraving processes. This eliminates the need for complex laser engraving, simplifying the steel plate processing steps and reducing the equipment and manpower required. It can accurately reproduce various pattern details, especially suitable for printing complex patterns, without worrying about the loss of pattern details.

[0022] An optical focusing device focuses, images, and identifies the center of the inkjet pattern, precisely locking the center coordinates of the pattern. This provides a precise basis for aligning the printing head with the pattern, ensuring accurate adhesion and avoiding instability in printing size caused by alignment deviations. It also improves alignment efficiency, eliminating the need for manual alignment and enhancing precise control over the printing process. During the printing head transfer process, the spacing, pressure, and contact time are adjusted to ensure the printing head completely absorbs the ink within the inkjet pattern, especially ensuring the integrity of ink absorption in complex pattern details. This also ensures complete and clear ink transfer to the contact lens surface, preventing issues such as blurry transfer or missed prints.

[0023] Surface curing of the transferred contact lenses allows the ink to solidify quickly, ensuring a tight bond between the ink and the lens surface. This prevents ink dripping and smudging, guaranteeing the stability of the printed pattern and preventing ink peeling and fading in subsequent processes, thus improving product quality. The system's functional modules work collaboratively and are electrically connected to the control system module, achieving automated control of the entire transfer printing process. This minimizes manual intervention, improves efficiency, ensures smooth transitions between steps, and precisely executes each step of the transfer printing method. It adapts to the transfer printing needs of various patterned contact lenses in mass production, further refining the accuracy and stability of the transfer printing process and meeting industry production requirements. Attached Figure Description

[0024] Figure 1 This is a flowchart of the method of the present invention;

[0025] Figure 2 This is a structural block diagram of the system of the present invention. Detailed Implementation

[0026] The invention will now be further described with reference to the accompanying drawings.

[0027] like Figure 1 As shown, a pad printing method for a colored contact lens VU printing machine includes the following steps:

[0028] S1. Prepare a flat steel plate and clean its surface. The specific steps for preparing a flat steel plate and cleaning its surface are as follows: Select a steel plate whose surface flatness meets the preset standard. First, use a dust-free wiping cloth dipped in special cleaning agent to wipe the surface of the steel plate in the same direction to remove dust, oil and impurities. Then, send the steel plate into the drying station and dry it with constant temperature hot air. After drying, check the dryness of the steel plate surface to ensure that the steel plate surface is dry without cleaning agent residue, scratches and stains.

[0029] S2. Printing patterns directly onto the surface of a flat steel plate using inkjet printing to form an inkjet pattern that matches the area to be printed on the contact lens; The specific steps for printing patterns directly onto the surface of a flat steel plate using inkjet printing are as follows: Using UV inkjet printing, select UV ink specifically for contact lens pad printing, and accurately spray the ink onto the surface of the flat steel plate through the inkjet printhead according to the preset pattern trajectory and fixed spray pressure, controlling the ink droplet diameter to be consistent, forming an inkjet pattern with uniform thickness and regular edges, and controlling the pattern thickness within the preset range to ensure that it matches the adsorption characteristics of the adhesive head;

[0030] S3. Focus and locate the inkjet pattern on the steel plate surface using an optical focusing device, identify the center position of the inkjet pattern and lock the coordinates; The specific steps for focusing and locating the inkjet pattern on the steel plate surface using an optical focusing device are as follows: The optical focusing device emits high-frequency detection light, which is perpendicularly irradiated onto the inkjet pattern area on the steel plate surface. The light reflected from the pattern is received and high-definition imaging is performed. The image recognition algorithm is used to extract the contour and calculate the center point of the image, accurately identify the center position of the inkjet pattern, and lock the X-axis and Y-axis coordinate parameters of the center position and transmit them to the control unit;

[0031] S4. Control the inkjet head to move above the locked center position, and adjust the distance between the inkjet head and the steel plate surface to ensure that the inkjet head is completely in contact with the inkjet pattern and absorbs the ink within the pattern. The specific steps for controlling the inkjet head to move above the locked center position are as follows: The servo drive mechanism moves the inkjet head. The servo drive mechanism receives coordinate parameters transmitted from the control unit and precisely controls the movement of the inkjet head along the X and Y axes. During the movement, the position of the inkjet head is calibrated in real time to ensure that the center of the inkjet head is precisely aligned with the center of the inkjet pattern. The alignment error is controlled within a preset range to ensure the accuracy of subsequent ink absorption and transfer. The specific steps for adjusting the distance between the inkjet head and the steel plate surface are as follows: After receiving coordinate parameters transmitted from the optical focusing and positioning module, the control unit drives the inkjet head to move along the Z axis. According to the preset thickness parameters of the inkjet pattern, the distance between the inkjet head and the steel plate surface is adjusted to a preset fixed value. During the adjustment process, the distance between the inkjet head and the steel plate is detected in real time to ensure that the inkjet head is completely in contact with the inkjet pattern without squeezing or damaging the pattern structure, ensuring the integrity of ink absorption.

[0032] S5. Move the ink-adsorbing adhesive head to the designated position of the contact lens to be transferred, adjust the adhesive head pressure and contact time, and transfer the ink to the surface of the contact lens;

[0033] S6. Perform surface curing treatment on the transferred contact lenses to complete the contact lens transfer printing operation; the specific steps for surface curing treatment on the transferred contact lenses are as follows: transfer the transferred contact lenses to the curing station, use a UV curing lamp to irradiate the ink on the surface of the contact lenses in a directional manner, control the irradiation power, irradiation distance and irradiation time of the UV curing lamp to make the ink cure quickly and form a shape, keep the position of the contact lenses fixed during the curing process to avoid ink dripping and smudging, and ensure that the ink is tightly bonded to the surface of the contact lenses after curing, without peeling or fading.

[0034] like Figure 2 As shown, a pad printing system for a UV inkjet printing machine for colored contact lenses includes a steel plate pretreatment module, an inkjet printing module, an optical focusing and positioning module, a printing head transfer module, a colored contact lens positioning module, a curing module, and a control system module. The steel plate pretreatment module includes a cleaning unit and a drying unit. The cleaning unit wipes and cleans the flat steel plate, and the drying unit dries the cleaned steel plate at a constant temperature. The inkjet printing module includes a UV inkjet printhead, an ink supply unit, and a motion drive unit, used to print patterns on the steel plate surface according to preset parameters. The optical focusing and positioning module includes a light source... The inkjet unit, imaging unit, and coordinate calculation unit are used to focus, center identify, and lock the coordinates of the inkjet pattern; the ink transfer module includes an inkjet head, servo drive unit, and pressure adjustment unit, used to absorb ink and transfer it to the contact lens; the contact lens positioning module is used to fix the contact lens to be printed and accurately position the printing area; the curing module includes a UV curing lamp and a station transfer unit, used to cure the ink on the transferred contact lens; the control system module is electrically connected to each module, used to receive feedback signals from each module and send control commands to achieve precise and coordinated control of the entire pad printing process.

[0035] Example 1

[0036] This embodiment is applied to the conventional pattern pad printing of colored contact lenses. The pad printing system of the aforementioned colored contact lens VU printing machine is used to perform the corresponding pad printing method. The specific process is as follows: The flat steel plate to be used is processed by the steel plate pretreatment module. The cleaning unit uses a special cleaning agent and a dust-free wiping method to wipe the surface of the steel plate to remove impurities and oil stains attached to the surface. Then the cleaned steel plate is sent to the drying unit for drying to ensure that there is no residue and no moisture on the surface of the steel plate.

[0037] After the steel plate pretreatment is completed, the control system module sends instructions to the inkjet printing module. The ink supply unit of the inkjet printing module provides UV ink for contact lens printing. The moving drive unit drives the UV inkjet printhead to spray ink onto the flat steel plate surface at a fixed spray pressure according to the preset contact lens pattern trajectory, forming an inkjet pattern with regular edges and uniform thickness.

[0038] After inkjet printing is completed, the optical focusing and positioning module starts working. The light emitting unit emits detection light that shines vertically onto the inkjet pattern area on the steel plate surface. The imaging unit receives the light reflected from the pattern and performs high-definition imaging. The coordinate calculation unit uses an image recognition algorithm to extract the contour and calculate the center point of the image, accurately identify the center position of the inkjet pattern and lock the coordinate parameters, and then transmits the coordinate parameters to the control system module.

[0039] Based on the received coordinate parameters, the control system module controls the servo drive mechanism of the inkjet transfer module to move the inkjet head precisely above the center of the inkjet pattern. Then, the inkjet head is driven to adjust the distance between itself and the steel plate surface along the Z-axis, so that the inkjet head completely adheres to the inkjet pattern and absorbs the ink within the pattern. After absorption is completed, the servo drive mechanism moves the inkjet head to the contact lens positioning module.

[0040] The contact lens positioning module has fixed the contact lens to be printed and accurately positioned the area to be printed. The control system module adjusts the pressure adjustment unit of the glue head transfer module, sets the appropriate glue head pressure and contact time, controls the glue head to contact the area to be printed on the contact lens, and completely transfers the absorbed ink to the surface of the contact lens.

[0041] After the transfer is completed, the transfer unit moves the transferred contact lens to the curing station. The UV curing lamp of the curing module irradiates the ink on the surface of the contact lens in a directional manner, so that the ink can be cured and formed quickly. After curing, the contact lens is taken out, completing a single contact lens transfer printing operation. The above steps can be repeated to achieve batch transfer printing.

[0042] Example 2

[0043] This embodiment is applied to the pad printing of complex patterns on colored contact lenses. The pad printing system of the aforementioned colored contact lens VU printing press is used to perform the corresponding pad printing method. The specific process is as follows: the flat steel plate is pre-treated by the steel plate pre-treatment module, the cleaning unit wipes the surface of the steel plate in the same direction to remove dust, oil and fine impurities, and the drying unit uses constant temperature hot air to dry the cleaned steel plate. After drying, the surface condition of the steel plate is inspected to ensure that it meets the requirements of inkjet printing.

[0044] After the preprocessing is qualified, the control system module sends control commands to the inkjet printing module. The inkjet printing module continuously supplies special UV ink by the ink supply unit according to the preset complex pattern parameters. The movement drive unit drives the UV inkjet printhead to move precisely and spray ink point by point according to the pattern trajectory to ensure that every detail of the complex pattern can be fully presented and form an inkjet pattern on the steel plate surface that matches the area to be printed on the contact lens.

[0045] After inkjet printing is complete, the optical focusing and positioning module begins focusing and positioning. The light emitting unit continuously emits high-frequency detection light to perform a comprehensive scan of the inkjet pattern. The imaging unit captures high-definition images of each area of ​​the pattern. The coordinate calculation unit performs detailed analysis of the images, accurately extracts the pattern outline and calculates the center position. After locking the coordinate parameters, the data is transmitted to the control system module in real time to ensure positioning accuracy.

[0046] The control system module controls the printing head transfer module to work according to the coordinate parameters. The servo drive mechanism drives the printing head to move precisely above the center of the inkjet pattern. The distance between the printing head and the steel plate surface is slowly adjusted so that the printing head is evenly attached to the entire inkjet pattern and fully absorbs the ink in the pattern, avoiding incomplete ink absorption in the details of complex patterns.

[0047] After the ink is absorbed, the servo drive mechanism moves the printing head to the contact lens positioning module. The contact lens positioning module has fixed the contact lens to be printed and positioned the area to be printed. The control system module adjusts the pressure and contact time of the printing head to ensure that complex patterns can be completely and clearly transferred to the surface of the contact lens. The status of the printing head is monitored in real time during the transfer process to ensure the transfer effect.

[0048] After the transfer is completed, the station transfer unit smoothly transfers the contact lens to the curing station. The UV curing lamp evenly irradiates the ink on the surface of the contact lens, allowing the ink to cure quickly. During the curing process, the position of the contact lens is kept fixed to avoid ink smudging or dripping. After curing, the complex pattern transfer of the contact lens is completed. The entire process is coordinated and controlled by the control system module, which ensures that the transfer process is stable and orderly.

Claims

1. A pad printing method for a colored contact lens VU printing machine, characterized in that, Includes the following steps: S1. Prepare a flat steel plate and clean its surface; S2. Printing patterns directly onto the surface of a flat steel plate using inkjet printing to form an inkjet pattern that matches the area to be printed on the contact lens. S3. Focus and locate the inkjet pattern on the surface of the steel plate using an optical focusing device, identify the center position of the inkjet pattern and lock the coordinates. S4. Control the glue head to move above the locked center position, adjust the distance between the glue head and the steel plate surface, so that the glue head is completely attached to the inkjet pattern and absorbs the ink in the pattern. S5. Move the ink-adsorbing adhesive head to the designated position of the contact lens to be transferred, adjust the adhesive head pressure and contact time, and transfer the ink to the surface of the contact lens; S6. Perform surface curing treatment on the transferred contact lenses to complete the contact lens transfer printing operation.

2. The pad printing method of a VU contact lens printing machine as described in claim 1, characterized in that, In step S2, the pattern is directly printed on the flat steel plate surface using inkjet printing. The specific steps are as follows: UV inkjet printing is used, and special UV ink for contact lens printing is selected. The ink is precisely sprayed onto the flat steel plate surface through the inkjet printhead according to the preset pattern trajectory and fixed spray pressure. The diameter of the ink droplets is controlled to be consistent, forming an inkjet pattern with uniform thickness and regular edges. The pattern thickness is controlled within the preset range to ensure that it matches the adsorption characteristics of the adhesive head.

3. The pad printing method for a colored contact lens VU printing machine as described in claim 1, characterized in that, In step S3, the inkjet pattern on the steel plate surface is focused and positioned by an optical focusing device. The specific steps are as follows: the optical focusing device emits high-frequency detection light, which is perpendicularly irradiated onto the inkjet pattern area on the steel plate surface. The light reflected from the pattern is received and high-definition imaging is performed. The image recognition algorithm is used to extract the contour and calculate the center point of the image to accurately identify the center position of the inkjet pattern. At the same time, the X-axis and Y-axis coordinate parameters of the center position are locked and transmitted to the control unit.

4. The pad printing method of a colored contact lens VU printing machine as described in claim 1, characterized in that, In step S4, the distance between the inkjet head and the steel plate surface is adjusted. The specific steps are as follows: After receiving the coordinate parameters transmitted by the optical focusing and positioning module, the control unit drives the inkjet head to move along the Z-axis. According to the preset thickness parameters of the inkjet pattern, the distance between the inkjet head and the steel plate surface is adjusted to a preset fixed value. During the adjustment process, the distance between the inkjet head and the steel plate is detected in real time to ensure that the inkjet head is completely in contact with the inkjet pattern without squeezing or damaging the pattern structure, thus ensuring the integrity of ink adsorption.

5. The pad printing method of a VU contact lens printing machine as described in claim 1, characterized in that, In step S6, the transferred contact lenses undergo surface curing treatment. The specific steps are as follows: the transferred contact lenses are transferred to the curing station, and a UV curing lamp is used to irradiate the ink on the surface of the contact lenses in a directional manner. The irradiation power, irradiation distance and irradiation time of the UV curing lamp are controlled to make the ink cure quickly. During the curing process, the position of the contact lenses is kept fixed to avoid ink dripping or smudging, and to ensure that the cured ink is tightly bonded to the surface of the contact lenses, without peeling or fading.

6. The pad printing method of a colored contact lens VU printing machine as described in claim 1, characterized in that, In step S1, a flat steel plate is prepared and its surface is cleaned. The specific steps are as follows: Select a steel plate whose surface flatness meets the preset standard. First, use a dust-free wiping cloth dipped in special cleaning agent to wipe the surface of the steel plate in the same direction to remove dust, oil and impurities. Then, send the steel plate to the drying station and dry it with constant temperature hot air. After drying, check the dryness of the steel plate surface to ensure that the steel plate surface is dry without cleaning agent residue, scratches and stains.

7. The pad printing method of a colored contact lens VU printing machine as described in claim 1, characterized in that, In step S4, the glue head is moved to the locked center position. The specific steps are as follows: the glue head is moved by the servo drive mechanism. The servo drive mechanism receives the coordinate parameters transmitted by the control unit and accurately controls the glue head to move along the X-axis and Y-axis. During the movement, the glue head position is calibrated in real time to ensure that the center of the glue head is accurately aligned with the center of the inkjet pattern. The alignment error is controlled within the preset range to ensure the accuracy of subsequent ink adsorption and transfer.

8. A pad printing system for a colored contact lens VU printing machine, used to implement the method of any one of claims 1 to 7, characterized in that, It includes a steel plate pretreatment module, an inkjet printing module, an optical focusing and positioning module, a glue transfer module, a contact lens positioning module, a curing module, and a control system module; The steel plate pretreatment module includes a cleaning unit and a drying unit. The cleaning unit wipes and cleans the flat steel plate, while the drying unit dries the cleaned steel plate at a constant temperature. The inkjet printing module includes a UV inkjet printhead, an ink supply unit, and a movement drive unit, used to print patterns on the steel plate surface according to preset parameters. The optical focusing and positioning module includes a light emitting unit, an imaging unit, and a coordinate calculation unit, used to complete the focusing, center recognition, and coordinate locking of the inkjet pattern. The ink transfer module includes an inkjet printhead, a servo drive unit, and a pressure adjustment unit, used to absorb ink and complete the transfer to the contact lens. The contact lens positioning module is used to fix the contact lens to be transferred and accurately position the area to be printed. The curing module includes a UV curing lamp and a station transfer unit, used to cure the ink on the transferred contact lens. The control system module is electrically connected to each module, used to receive feedback signals from each module and send control commands to achieve precise and coordinated control of the entire transfer printing process.

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