A planar color hot stamping method based on laser transfer

Abstract

The application provides a planar color hot stamping equipment based on laser transfer printing, which comprises a control system, a laser, an XY two-dimensional scanning galvanometer system, a feeding unit and a three-primary-color hot stamping film; the three-primary-color hot stamping film comprises a carrier substrate and a three-primary-color pigment layer coated on the carrier substrate; the carrier substrate is required to have laser transparency and non-absorption; the three-primary-color pigment layer comprises a red color region, a green color region and a blue color region, and each color region is coated with a thin planar film formed by the color coating. The application can realize pigment deposition at any position of the object to be printed through the scanning of the XY two-dimensional scanning galvanometer system, and can conveniently realize large-format color hot stamping; and through the regulation and control of process parameters such as laser pulse energy, pulse number and the like, different amounts of three-primary-color pigment jetting mixing can be realized, and the color reproduction degree is high. The application also simultaneously provides a planar color hot stamping method based on laser transfer printing.

Description

[0001] This application is a divisional application of application number 202211141053.6, filed on 2022-09-19, entitled "A planar color hot stamping device and method based on laser transfer". Technical Field

[0002] This invention belongs to the field of color hot stamping technology, specifically relating to a planar color hot stamping device and method based on laser transfer. Background Technology

[0003] Existing color hot stamping equipment often uses hot pressing and other methods to stamp color patterns or pigments onto the target substrate. However, it generally suffers from problems such as complex structure, limited stamping area, and insufficient flexibility and adaptability.

[0004] Chinese utility model patent No. 91224573.5 discloses a portable multi-functional color hot stamping machine. During color printing, different letterheads can be fixed on four letter plates as needed. Different colored inks are then rolled onto the letterheads to evenly coat them. The handwheel is rotated sequentially, and the pressure handle is pressed down to complete the color printing operation. However, this hot stamping machine requires the preparation of corresponding colored inks and letterheads for different color hot stamping needs, resulting in complex operation and high costs.

[0005] Chinese invention patent No. 200810195783.8 discloses a polyethylene plastic for color hot stamping and a hot stamping method thereof. This method uses hot stamping foil as a film carrier pigment and a mold containing text and / or patterns as a tool to transfer the pigment and text and / or patterns to the substrate surface via hot pressing. However, this hot stamping method requires pre-preparation of a hot stamping head and pigment containing the desired text and patterns, and is mainly applicable to planar substrates, resulting in drawbacks such as limited stamping area, cumbersome steps, and high cost. Summary of the Invention

[0006] To address the shortcomings of the prior art, this invention provides a planar color hot stamping device based on laser transfer, and also provides a planar color hot stamping method based on laser transfer.

[0007] This invention is achieved through the following technical solution:

[0008] A planar color hot stamping method based on laser transfer includes the following steps:

[0009] (1) Analyze the color digital image to be printed and determine the values ​​of the R, G, and B components of each pixel;

[0010] (2) Based on the value of the A color component of each pixel obtained in step (1), and the relationship between the number of laser scans and the A color brightness value under specific laser scanning parameters, calculate the N of each pixel when transferring the A color. i The corresponding number of laser scans K i Color A is one of the three primary colors: red, green, and blue.

[0011] (4) Adjust the A color area of ​​the three primary color hot stamping film to the bottom of the XY two-dimensional scanning galvanometer system so that the scanning range of the XY two-dimensional scanning galvanometer system can completely cover the A color area, and the laser beam output by the laser is focused on the thin flat film of the A color area after passing through the XY two-dimensional scanning galvanometer system.

[0012] The three-primary-color hot stamping film includes a carrier substrate and a three-primary-color pigment layer coated on the carrier substrate; the carrier substrate is required to be laser transparent and non-absorbent; the three-primary-color pigment layer includes red color areas, green color areas and blue color areas, and each color area is coated with a thin planar film formed by the color paint;

[0013] The workpiece to be printed is clamped below the A color area, and is parallel to and close to the lower surface of the A color area, with a distance of 0.05mm to 2mm.

[0014] (4) Using the specific laser scanning parameters in step (2), control the laser output beam to scan the A color area several times, so that A color paint is deposited on the surface of the workpiece during each scan. It is required that the j-th scan should scan all the laser scan times K. i Pixels ≥ j, where j ≥ 1; after all scans are completed, each pixel N i The corresponding number of laser scans is K. i This transfers a single A-color image onto the surface of the workpiece.

[0015] (5) Following the method of steps (2)-(4), transfer the single images of the other two colors to the surface of the workpiece in sequence, and finally form an RGB color image on the surface of the workpiece.

[0016] The present invention has the following beneficial effects:

[0017] 1. Existing color hot stamping equipment requires different stamping heads or hot pressing for different patterns, resulting in complex equipment structures and cumbersome processes. The planar color hot stamping equipment described in this invention uses laser pulse in-situ pigment deposition to achieve color hot stamping, requiring only a laser and a stamping film, eliminating the need for a pad printing roller. It has the advantages of simple structure, high efficiency, and low cost of consumables and equipment.

[0018] 2. The planar color hot stamping equipment of the present invention, through scanning by an XY two-dimensional scanning galvanometer system, can achieve pigment deposition at any position on the workpiece to be printed, and can easily realize large-format color hot stamping. Moreover, the laser spot diameter is small, the pulse width is narrow, and the control precision is high, which can achieve high-precision pigment deposition (below 10 micrometers); by adjusting process parameters such as laser pulse energy and pulse number, different amounts of the three primary color pigments can also be sprayed and mixed, resulting in high color reproduction.

[0019] 3. In the planar color hot stamping equipment of the present invention, the pigment film on the three primary color hot stamping film is transferred to the surface of the workpiece to be printed in the form of micro droplets or particles after being heated by laser pulse. After contacting the surface of the workpiece to be printed, it cools and solidifies, and is firmly bonded to the surface of the workpiece to be printed, and is not easy to fall off. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the planar color hot stamping equipment described in this invention. Detailed Implementation

[0021] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0022] like Figure 1 As shown, the present invention provides a planar color hot stamping device based on laser transfer, including a control system 1, a laser 2, an XY two-dimensional scanning galvanometer system 3, a feeding unit 4, and a three-primary-color hot stamping film 5.

[0023] Laser 2 is used to emit a laser beam, which can be a nanosecond, picosecond, or femtosecond laser, preferably a femtosecond laser.

[0024] The laser beam emitted from laser 2 is incident on the XY two-dimensional scanning galvanometer system 3. The XY two-dimensional scanning galvanometer system 3 collimates the laser beam before reflecting it through X and Y axis mirrors and focusing it through a focusing lens, outputting it onto the focusing working plane. Either rear-focusing or front-focusing can be used. Controlling the rotation of the X and Y axes allows the laser beam to move on the focusing working plane. The scanning range of the XY two-dimensional scanning galvanometer system 3 must completely cover one color area of ​​the three primary color hot stamping film 5.

[0025] The three-primary-color hot stamping film 5 includes a carrier substrate and a three-primary-color pigment layer coated on the carrier substrate. The carrier substrate is required to have laser transparency and non-absorption, that is, a laser transmittance greater than 90% and a laser absorption rate less than 5%. The carrier substrate can be a fused silica carrier or a polymer film, etc.

[0026] The three primary color pigment layer includes a red color region 51, a green color region 52, and a blue color region 53, each of which is coated with a thin planar film formed from that color pigment. The three color regions (red, green, and blue) are arranged along the length of the three primary color hot stamping film 5, and all three have the same length, width, and thin planar film thickness. The thickness of the thin planar film is preferably 5–20 μm.

[0027] The size of the carrier substrate can be larger than the size of the three primary color pigment layers, with gaps at both ends for mounting the three primary color hot stamping film 5 onto the feeding unit 4, and the feeding unit 4 can drive the three primary color hot stamping film 5 to translate along its length. Alternatively, the carrier substrate can be the same size as the three primary color pigment layers, in which case additional connectors are needed to mount the three primary color hot stamping film 5 onto the feeding unit 4.

[0028] The feeding unit 4 is used to clamp the three primary color hot stamping film 5 and drive the three primary color hot stamping film 5 to make a back-and-forth translational movement along its length direction, and ensure that the surface of the three primary color hot stamping film 5 always remains horizontal, and the distance of each movement of the feeding unit 4 is the width of one color area.

[0029] The installation requirements for the three primary color hot stamping film 5 are as follows: the carrier substrate faces upwards, towards the XY two-dimensional scanning galvanometer system 3; the three primary color pigment layers face downwards, towards the workpiece 7 to be printed. The red, green, and blue color areas are all required to be exposed outside the feeding unit 4, and the upper surfaces of the red, green, and blue color areas are all on the same plane as the focusing working plane.

[0030] The workpiece 7 to be printed is clamped and fixed by the clamp 6. The surface of the workpiece 7 to be printed is parallel to and very close to the lower surfaces of the red, green and blue color areas, and the distance between them is required to be within the range of 0.05mm to 2mm.

[0031] When the laser beam is incident on the three primary color hot stamping film 5, it passes through the carrier substrate and focuses on a thin planar film in a certain color area. By adjusting the applied laser energy, a forward thrust can be generated within the irradiated film volume. The absorbed laser photons cause partial ablation of the film material, thereby causing a rapid volume expansion and pressure jump, which pushes the coating on the film material away and catalytically deposits it onto the receiving surface, i.e., the surface to be printed on the workpiece 7.

[0032] This invention also provides a planar color hot stamping method based on laser transfer. The basic idea is to first decompose the RGB color image to be hot stamped into three component images: red, green, and blue. Then, using laser transfer technology, a specific color coating is deposited onto the receiving surface to form a single-color component image. Then, based on this single-color component image, a second and third color component images are superimposed and deposited to finally form an RGB color image on the receiving surface.

[0033] This method is implemented through the following steps:

[0034] (1) Analyze the color digital image to be printed and determine the values ​​of the R, G, and B components of each pixel.

[0035] (2) Based on the value of the A color component of each pixel obtained in step (1) (A color is one of the three primary colors of red, green and blue), and the relationship between the number of laser scans and the A color brightness value under specific laser scanning parameters, calculate N for each pixel when transferring A color. i The corresponding number of laser scans K i .

[0036] The relationship between the number of laser scans and the brightness value of color A under specific laser scanning parameters needs to be obtained experimentally before hot stamping. The specific method is as follows:

[0037] The A color area of ​​the three primary color hot stamping film 5 is adjusted to be below the XY two-dimensional scanning galvanometer system 3, so that the scanning range of the XY two-dimensional scanning galvanometer system 3 can completely cover the A color area of ​​the three primary color hot stamping film 5, and the laser beam is focused on the thin flat film of the A color area, and the blank test piece is clamped below the A color area.

[0038] With the laser scanning parameters adjusted, the laser is controlled to scan once along the set path, so that the A-color coating in the scanned area is deposited on the surface of the test piece. Then, the A-color image on the surface of the test piece is analyzed by image processing software to obtain the average A-color brightness value of the image.

[0039] Then, using the same laser scanning parameters and the same scanning path, the test piece was subjected to an increasing number of laser scanning experiments. The relationship between the number of laser scannings and the brightness value of color A was obtained through fitting.

[0040] (3) Adjust the A color area of ​​the three primary color hot stamping film 5 to the lower part of the XY two-dimensional scanning galvanometer system 3 so that the scanning range of the XY two-dimensional scanning galvanometer system 3 can completely cover the A color area of ​​the three primary color hot stamping film 5, and the laser beam is focused on the thin flat film of the A color area. The workpiece 7 to be printed is clamped below the A color area and is parallel to and very close to the lower surface of the A color area. The distance between them is required to be within the range of 0.05mm to 2mm.

[0041] (4) Using the specific laser scanning parameters in step (2), control the laser output beam to scan the A color area several times, so that A color paint is deposited on the surface of the workpiece 7 during each scan. It is required that the j-th scan should scan all the laser scan times K. i Pixels with values ​​greater than or equal to j, where j ≥ 1. This ensures that after all pixels are scanned, each pixel N is found to be a valid pixel.i The corresponding number of laser scans is K. i This transfers a single A-color image onto the surface of the workpiece 7.

[0042] (5) Following the method of steps (2)-(4), transfer the single images of the other two colors to the surface of the workpiece 7 in sequence, and finally form an RGB color image on the surface of the workpiece 7.

[0043] Preferably, after the three primary colors are deposited, the three primary color hot stamping film 5 can be removed, so that the laser beam can be directly incident on the surface of the workpiece 7 to scan the image once, thereby promoting the fusion of the three primary colors.

[0044] It will be apparent to those skilled in the art that the present invention can be modified in various ways, and such modifications are not considered to depart from the scope of the invention. All such modifications that are obvious to those skilled in the art are included within the scope of the claims.

Claims

1. A laser transfer-based flat color stamping method, characterized by, The method comprises the following steps: (1) analyzing a color digital image to be printed to determine the value of R, G and B components of each pixel; (2) calculating the number of laser scanning times for each pixel point in the transfer of the A color according to the value of the A color component of each pixel obtained in step (1) and the relationship between the number of laser scanning times and the A color brightness value under specific laser scanning parameters Ni corresponding number of laser scanning times Ki , and the A color is one of red, green and blue. (3) adjusting the A color area of the three-primary-color stamping film to be below the XY two-dimensional scanning galvanometer system, so that the scanning range of the XY two-dimensional scanning galvanometer system can completely cover the A color area, and the laser beam output by the laser is focused on the thin planar film of the A color area after passing through the XY two-dimensional scanning galvanometer system; The three-primary-color stamping film comprises a carrier substrate and a three-primary-color pigment layer coated on the carrier substrate; the carrier substrate is required to have laser transparency and non-absorption; the three-primary-color pigment layer comprises a red color area, a green color area and a blue color area, and each color area is coated with a thin planar film formed by the color coating; The object to be printed is clamped below the A color area and parallel to the lower surface of the A color area with a distance within the range of 0.05mm to 2mm; (4) using the specific laser scanning parameters in step (2), controlling the laser to output a laser beam, and scanning the A color region for several times so that A color paint is deposited on the surface of the printed matter each time, and all laser scanning times are scanned in the jth scanning, where j≥1; after all scanning is completed, each pixel point Ki corresponds to the jth scanning times, where j≥1; after all scanning is completed, each pixel point Ni corresponds to the jth scanning times, where j≥1; after all scanning is completed, each pixel point Ki , so as to transfer the image of a single A color to the surface of the printed matter; (5) according to the method of steps (2)-(4), sequentially transfer the single images of the other two colors to the surface of the object to be printed, and finally form an RGB color image on the surface of the object to be printed.

2. The planar color stamping method according to claim 1, wherein After the deposition of the three primary colors is completed, the three-primary-color stamping film is removed, so that the laser beam is directly incident on the surface of the object to be printed, and the image is scanned once to promote the fusion of the three primary colors.

3. The planar color stamping method according to claim 1, wherein The relationship between the number of laser scans under specific laser scanning parameters and the A color brightness value in step (2) needs to be obtained by experimental method before stamping; the specific method is as follows: Adjust the A color area of the three-primary-color stamping film to be below the XY two-dimensional scanning galvanometer system, so that the scanning range of the XY two-dimensional scanning galvanometer system can completely cover the A color area of the three-primary-color stamping film, and the laser beam is focused on the thin planar film of the A color area, and the test object with a blank surface is clamped below the A color area; Under the adjusted laser scanning parameters, control the laser to scan once according to the set path, so that the A color coating of the scanned area is deposited on the surface of the test object, and then analyze the A color image on the surface of the test object by image processing software to obtain the average A color brightness value of the image; then, using the same laser scanning parameters and the same scanning path, the test object is subjected to laser scanning experiment with increasing number of times, and the relationship between the number of laser scans and the A color brightness value is obtained by fitting.

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