JP2026017034A - Printing device and printing method - Google Patents

Abstract

Achieve both high visibility and high-speed printing without increasing the size, cost, or life of the device.
[Solution] A printing device capable of printing any pattern by irradiating a laser beam onto a surface of an object to be printed, comprising: a laser beam generating unit that oscillates laser beam; a laser beam diameter adjusting unit that adjusts the beam diameter of laser beam of a predetermined wavelength oscillated from the laser beam generating unit; a laser beam branching unit that transmits and reflects the laser beam by polarization, the laser beam diameter of which has been adjusted by the laser beam diameter adjusting unit; a laser beam scanning unit that two-dimensionally scans the laser beam that has passed through the laser beam branching unit; a laser beam irradiating unit that irradiates the object to be printed with the laser beam scanned by the laser beam scanning unit; a laser beam measuring unit that measures the light reflected from the object to be printed; and a focus control unit that controls the laser beam diameter adjusting unit using the laser beam measuring unit, and the focus control unit controls the focus position of the laser beam irradiated onto the object to be printed by the laser beam irradiating unit based on the shape of the laser beam of the reflected light measured by the laser beam measuring unit.
[Selected Figure] Figure 1

Description

The present invention relates to a printing device and a printing method.

Recently, laser markers (LMs) have become popular because they are highly minute, indestructible, and suitable for traceability. For example, Patent Document 1 describes a device that "includes a distance measurement pointer light emitter (460) that emits a pointer light toward the surface of a workpiece, an imaging unit (456) that has a light receiving axis branching from the emission axis of the laser beam and captures an image of a bright spot created on the workpiece surface when the pointer light strikes it, a memory that records distance derivation information for deriving the working distance, and working distance measurement means that calculates the working distance based on the distance derivation information in the memory and the position of the bright spot in the image captured by the imaging unit."

JP 2016-036841 A

In order to achieve high visibility and high-speed printing with a laser marker, it is necessary to increase the output of the laser that serves as the light source, but this creates problems such as larger equipment, higher costs, and a shorter lifespan. Therefore, rather than simply increasing the laser power, it is important to effectively utilize the laser power energy within a range appropriate for the object being marked, thereby minimizing these problems and achieving both high visibility and high-speed printing without print smearing.

While high visibility can be achieved by printing with energy appropriate for the object to be printed, visibility can be reduced unless the position of the laser beam spot is properly controlled by detecting its position relative to the object to be printed. To avoid this problem, focus control can be performed by measuring the position of the beam spot using a distance sensor that measures the distance to the object to be printed. However, adding a new distance sensor is not necessarily an appropriate method due to the increased size and cost of the device, as mentioned above.

Furthermore, in order to perform appropriate focus control on a variety of printing targets, including not only flat surfaces but also curved and three-dimensional shapes, there are limits to the accuracy of visibility when simply measuring the position of the laser beam spot indirectly using a distance sensor. Therefore, in order to achieve high visibility on a variety of printing targets, it is desirable to measure the position of the laser beam spot directly by measuring the shape of the beam spot. Then, by quickly performing focus control on the printing target, it becomes possible to achieve both the high visibility and high-speed printing described above.

Patent Document 1 and other prior art technologies do not address these issues, and there has been a demand for technology that can achieve both high visibility and high-speed printing without increasing the size, cost, or shortening the lifespan of the device.

The objective of the present invention is to provide a printing device and printing method that can achieve both high visibility and high-speed printing without increasing the size, cost, or lifespan of the device.

The printing device of the present invention is capable of printing any pattern by irradiating a laser beam onto the surface of a printing object. It includes a laser beam generating unit that oscillates laser beam; a laser beam diameter adjusting unit that adjusts the beam diameter of the laser beam of a predetermined wavelength emitted from the laser beam generating unit; a laser beam branching unit that transmits and reflects the laser beam by polarization, the laser beam diameter of which has been adjusted by the laser beam diameter adjusting unit; a laser beam scanning unit that two-dimensionally scans the laser beam that has passed through the laser beam branching unit; a laser beam irradiating unit that irradiates the printing object with the laser beam scanned by the laser beam scanning unit; a laser beam measuring unit that measures the light reflected from the printing object; and a focus control unit that controls the laser beam diameter adjusting unit using the laser beam measuring unit, and the focus control unit controls the focus position of the laser beam irradiated onto the printing object by the laser beam irradiating unit based on the shape of the laser beam of the reflected light measured by the laser beam measuring unit.

This invention makes it possible to achieve both high visibility and high-speed printing without increasing the size, cost, or lifespan of the device.

FIG. 2 is a diagram illustrating an example of a functional configuration of a laser marker according to a first embodiment. FIG. 2 is a diagram illustrating an example of a physical configuration of the laser marker illustrated in FIG. 1 . 10 is a flowchart showing an example of a processing procedure for marking processing in which a laser beam shape is measured and laser marking is performed in the present embodiment. FIG. 10 is a diagram illustrating an example of a functional configuration of a laser marker according to a second embodiment. FIG. 5 is a diagram illustrating an example of the physical configuration of the laser marker illustrated in FIG. 4. 10A and 10B are diagrams for explaining how a center-of-gravity position measuring sensor measures the center-of-gravity position of laser light; 10 is a flowchart showing an example of a processing procedure for marking processing in which a laser beam shape is measured and laser marking is performed in the present embodiment. 10 is a flowchart showing another example of the processing procedure of the marking process for measuring the laser beam shape and performing laser marking in the present embodiment. FIG. 10 is a diagram illustrating an example of the functional configuration of a laser marker according to a third embodiment. FIG. 10 is a diagram illustrating an example of the physical configuration of the laser marker illustrated in FIG. 9 . 10 is a flowchart showing an example of a processing procedure for marking processing in which a laser beam shape is measured and laser marking is performed in the present embodiment. 10 is a flowchart showing another example of the processing procedure of the marking process for measuring the laser beam shape and performing laser marking in the present embodiment.

Embodiments of the present invention will be described below with reference to the drawings. The examples are illustrative only and have been omitted or simplified as appropriate for clarity of explanation. The present invention can also be implemented in various other forms. Unless otherwise specified, each component may be singular or plural. The position, size, shape, range, etc. of each component shown in the drawings may not represent the actual position, size, shape, range, etc., in order to facilitate understanding of the invention. Therefore, the present invention is not necessarily limited to the position, size, shape, range, etc. disclosed in the drawings.

Furthermore, when there are multiple components with the same or similar functions, they may be described using the same reference numeral with different subscripts. Furthermore, when there is no need to distinguish between these multiple components, the subscripts may be omitted.

In the embodiments, processing performed by executing a program may be described. Here, a computer executes the program using a processor (e.g., a CPU or GPU) and performs the processing defined in the program using storage resources (e.g., memory) and interface devices (e.g., communication ports). Therefore, the entity performing the processing by executing the program may be the processor. Similarly, the entity performing the processing by executing the program may be a controller, device, system, computer, or node having a processor. The entity performing the processing by executing the program may be any computing unit, and may include a dedicated circuit that performs specific processing. Here, a dedicated circuit is, for example, an FPGA (Field Programmable Gate Array), ASIC (Application Specific Integrated Circuit), or CPLD (Complex Programmable Logic Device).

A program may be installed on a computer from a program source. The program source may be, for example, a program distribution server or a computer-readable storage medium. When the program source is a program distribution server, the program distribution server may include a processor and storage resources for storing the program to be distributed, and the processor of the program distribution server may distribute the program to be distributed to other computers. In addition, in the embodiments, two or more programs may be realized as one program, or one program may be realized as two or more programs.
Example 1
FIG. 1 is a diagram showing an example of the functional configuration of a laser marker 1000 in Example 1. The laser marker 1000 is a device capable of printing any pattern by irradiating a laser beam of a predetermined wavelength onto a surface of an object to be printed. As shown in FIG. 1, the laser marker 1000 includes a print pattern input unit 10 that accepts input of a print pattern to be printed on the object to be printed (e.g., the number "0" that constitutes part of a serial number), a print coordinate generation unit 11 that generates coordinates on the object to be printed 7 of the print pattern input by the print pattern input unit 10, a print control unit 12 that controls each unit of the laser marker 1000, a laser beam generation unit 1 that oscillates a laser beam of a predetermined wavelength, a laser beam diameter adjustment unit 2 that adjusts the beam diameter of the laser beam of the predetermined wavelength oscillated from the laser beam generation unit 1, and a laser beam output unit 3 that adjusts the beam diameter of the laser beam of the predetermined wavelength oscillated from the laser beam generation unit 1. The laser beam splitter 3 transmits and reflects the beam whose diameter has been adjusted by the diameter adjustment unit 2 using polarization; a laser beam scanning unit 4 and a laser beam scanning unit 5 which two-dimensionally scan the beam that has passed through the laser beam splitter 3; a laser beam irradiation unit 6 which irradiates the beam scanned by the laser beam scanning unit 4 and the laser beam scanning unit 5 onto an object to be printed 7; a laser beam measuring unit 8 which measures the light reflected from the object to be printed 7; and a focus control unit 9 which performs focus control such as controlling the focal position based on the laser beam shape of the reflected light obtained from the signal measured by the laser beam measuring unit 8.

2 is a diagram showing an example of the physical configuration of the laser marker 1000 shown in FIG. 1. As shown in FIG. 2, the laser marker 1000 physically includes a laser light source 1a operating as the laser light generator 1, a beam expander 2a operating as the laser beam diameter adjuster 2, a beam splitter 3a and a quarter-wave plate 3b operating as the laser beam brancher 3, an X mirror 4a and a Y mirror 4b operating as the laser beam scanner 4 and the laser beam scanner 5, driven as the galvanometer mirrors of the galvanometer scanner, an fθ lens 6a for focusing the light and operating as the laser beam irradiation unit 6, an imaging lens 8a and a line sensor 8b for measuring the shape of the laser beam and operating as the laser beam measurement unit 8, and a measurement error generation circuit 9a operating as the focus control unit 9. The X mirror 4a is scanned in the X-axis direction shown in FIG. 2, and the Y mirror 4b is scanned in the Y-axis direction shown in FIG. 2. The print pattern input unit 10, print coordinate generation unit 11, and print control unit 12 can be realized by a general computer with a processor and memory executing a program.

In FIG. 2, the laser beam L1 emitted from the laser source 1a has its laser beam diameter (e.g., spot size and divergence angle) adjusted by the beam expander 2a. The adjusted laser beam L1 is then reflected by the X mirror 4a and Y mirror 4b, which scan the laser beam L1, and enters the focusing fθ lens 6a, which focuses the laser beam. The laser beam is then focused at laser beam spot position P1 on the target object 7, which is placed at the focal position of the focusing fθ lens 6a, thereby marking the target object 7. Reflected light L2 from laser beam spot position P1 passes through the quarter-wave plate 3b and beam splitter 3a and is detected by the line sensor 8b. For example, the line sensor 8b measures a Gaussian laser beam shape F1 as the detected reflected light L2. Here, a Gaussian laser beam shape is illustrated, but other laser beam shapes, such as a top hat shape or a ring shape, may also be measured.

Then, from the measurement results, the measurement error generation circuit 9a calculates the amount of deviation from the desired laser beam shape and center of gravity position, and adjusts the divergence angle of the beam expander 2a according to this deviation. This type of control makes it possible to directly control the laser beam shape and laser beam spot position.

Typically, laser markers are designed to produce clear printing at the exact focus position. Therefore, the further the focus deviates from this position, the wider the spot becomes, the lower the energy density becomes, and the lighter the printing becomes. To avoid this problem, prior art technologies have used a newly added distance sensor to measure the distance to the object being printed, allowing for indirect adjustment of the laser light spot position. However, this method of pseudo-measuring the laser light spot position using a distance sensor does not necessarily allow for accurate adjustment of the laser light shape or laser light spot position, making it difficult to achieve high-precision focus control. According to this embodiment, by directly monitoring the laser light shape and laser light spot position without using the distance sensor described above, the laser light shape and laser light spot position can be quickly changed, achieving unprecedented high-precision focus control on the object being printed (7) and improving printing speed with good visibility.

Figure 3 is a flowchart showing an example of the marking process steps for measuring the laser beam shape and performing laser marking in this embodiment.

As shown in FIG. 3, the print pattern input unit 10 accepts a print pattern input by a user (S101). A general computer with an interface such as a touch panel can be used as the print pattern input unit 10. The print pattern input unit 10 does not necessarily have to be provided in the laser marker 1000; the laser marker 1000 may receive the print pattern from the print pattern input unit 10. Furthermore, the print pattern includes various identification information to be printed on the printing target, such as numbers such as "0" and "1" or letters such as "A" and "B," as well as various information that can be marked by a laser marker.

The print coordinate generation unit 11 generates coordinates (x, y) for printing the print pattern input in S101 (S102). As with the print pattern input unit 10, a general-purpose computer can be used as the print coordinate generation unit 11. The coordinates are, for example, information representing the positions of the lines that make up the print pattern on the plane of the print target 7.

The printing control unit 12 scans the laser light scanning unit 4 and the laser light scanning unit 5 so that the position of the coordinates (x, y) generated in S102 becomes the laser light spot position P1, and prints the printing pattern on the printing object 7 (S103).

When the print pattern is printed on the print target 7, reflected light L2 from laser light spot position P1 passes through the focusing fθ lens 6a, X mirror 4a and Y mirror 4b, quarter-wave plate 3b, and beam splitter 3a and reaches line sensor 8b. Line sensor 8b detects the reflected light L2, and the print control unit 12 measures the laser light shape from the brightness of the detected reflected light L2. The print control unit 12 then calculates the center of gravity position on line sensor 8b for the identified laser light shape and compares the calculated center of gravity position on line sensor 8b with the center of gravity position of a predetermined desired laser light shape (S104).

The print control unit 12 determines whether the calculated center of gravity position on the line sensor 8b satisfies predetermined conditions with respect to the center of gravity position of the desired laser beam shape (S105). For example, the print control unit 12 determines whether the calculated center of gravity position on the line sensor 8b is within a range of ±5% with respect to the center of gravity position of the desired laser beam shape.

If the print control unit 12 determines that the calculated center of gravity position on the line sensor 8b is within a range of ±5% of the center of gravity position of the desired laser beam shape (S105; Yes), it maintains the position of the divergence angle adjustment element of the beam expander 2a (S106) and proceeds to S108.

On the other hand, if the print control unit 12 determines that the calculated center of gravity position on the line sensor 8b is not within a range of ±5% of the center of gravity position of the desired laser beam shape (S105; No), it instructs the measurement error generation circuit 9a to change the position of the divergence angle adjustment element of the beam expander 2a. The measurement error generation circuit 9a changes the position of the divergence angle adjustment element of the beam expander 2a in accordance with the instruction (S107). Thereafter, the process returns to step S105, and the measurement error generation circuit 9a performs control to change the position of the divergence angle adjustment element so that it is within the above range.

After executing S106, the printing control unit 12 determines whether printing has been completed for all coordinates (x, y) generated in S102 (S108), and if it determines that printing has been completed for all coordinates (x, y) generated in S102 (S108; Yes), it terminates this processing.

On the other hand, if the printing control unit 12 executes S106 and determines that printing has not been performed for all of the coordinates (x, y) generated in S102 (S108; No), it returns to S103 and repeats the subsequent processing until printing has been performed for all of the coordinates (x, y).

As described above, according to the laser marker 1000 of this embodiment, focus control is performed based on the laser beam shape of the reflected light L2, so that high visibility and high-speed printing can be achieved simultaneously without increasing the size, cost, or lifespan of the device.
Example 2
In Example 1, high visibility and high-speed printing were achieved by directly controlling focus based on the laser beam shape of the reflected light obtained from the laser beam spot position. When performing laser marking, since the laser beam is invisible, the laser beam spot position and laser beam intensity must be adjusted while marking the target object. In the following, to facilitate such adjustments with precision, a spot monitor function for monitoring the laser beam spot position and laser beam intensity is further provided. By adopting this configuration, time-series data on defocus printing and printing power can be acquired, and this data can be used as command values for a beam expander to expand the spot diameter of the laser beam spot. As a result, a single laser marker can monitor the laser beam spot position and laser beam intensity for laser beams of various shapes, reducing implementation costs and enabling high-speed printing while understanding the recording status and preventing print distortion.

Figure 4 is a diagram showing an example of the functional configuration of the laser marker 2000 in Example 2. Like the laser marker 1000 in Example 1, the laser marker 2000 is a device that can print any pattern by irradiating the surface of an object to be printed with laser light of a predetermined wavelength. Below, the same components as those in the laser marker 1000 in Example 1 will be assigned the same reference numerals and their description will be omitted, and the following will mainly describe the configuration that differs from the laser marker 1000.

As shown in FIG. 4, the laser marker 2000 has the same laser light generating unit 1, laser light diameter adjusting unit 2, laser light branching unit 3, laser light scanning unit 4 and laser light scanning unit 5, laser light irradiation unit 6, and print control unit 12 as the laser marker 1000 in Example 1, but also a laser light measuring unit 80 and focus control unit 90 that are different from the laser marker 1000 in Example 1. The laser light measuring unit 80 is, for example, a sensor for measuring the laser light shape and center of gravity position of the reflected light. The focus control unit 90 is, for example, a circuit for performing focus control, such as controlling the focal position, based on the laser light shape and center of gravity position of the reflected light measured by the laser light measuring unit 80.

Figure 5 is a diagram showing an example of the physical configuration of the laser marker 2000 shown in Figure 4. As shown in Figure 5, the laser marker 2000 physically has a laser light source 1a, a beam expander 2a, a beam splitter 3a and a quarter-wave plate 3b, an X mirror 4a and a Y mirror 4b, and an fθ lens 6a for focusing, similar to the laser marker 1000 in Example 1.

The laser marker 2000 also includes an imaging lens 80a and line sensor 80b for measuring the shape of the laser beam, an imaging lens 80c and center of gravity position measurement sensor 80d for measuring the center of gravity position, and a half beam splitter 80e that splits the reflected light from the laser beam spot position, all of which function as the laser beam measurement unit 80. The laser marker 2000 also includes a measurement error generation circuit 90a that uses signals output from the line sensor 80b and center of gravity position measurement sensor 80d to adjust the laser beam spot position and the intensity of the laser beam. An OEIC (Optoelectronic Integrated Circuit) or various cameras can be used as the center of gravity position measurement sensor 80d.

In Figure 5, as in Example 1, laser light L1 adjusted by beam expander 2a is reflected by X mirror 4a and Y mirror 4b, passes through focusing fθ lens 6a, and is then marked on the printing target 7. Reflected light L2 from laser light spot position P1 passes through quarter-wave plate 3b and beam splitter 3a and is input to laser light measurement unit 80. The input reflected light L2 is split by half beam splitter 80e of laser light measurement unit 80. As in Example 1, one of the split reflected light beams passes through imaging lens 80a and is input to line sensor 80b, where the laser light shape of the reflected light L2 is measured. For example, as in Example 1, line sensor 80b measures a Gaussian laser light shape F1 as the reflected light L2.

Meanwhile, the other branched reflected light passes through the imaging lens 80c and is input to the center of gravity position measurement sensor 80d, thereby measuring the center of gravity position of the reflected light L2.

Figure 6 is a diagram illustrating how the center-of-gravity position measurement sensor 80d measures the center-of-gravity position of the laser light. Here, we will explain the case where the center-of-gravity position measurement sensor 80d is an OEIC.

As shown in Figure 6, the output signal of the OEIC that constitutes the center of gravity position measurement sensor 80d is classified into three patterns depending on the positional relationship between the beam spot and the object to be printed. For example, it can be classified into (a) a pattern in which the beam spot is formed in front of the object to be printed, (b) a pattern in which the beam spot is formed on the object to be printed, and (c) a pattern in which the beam spot is formed behind the object to be printed. In this example, in (a), a signal is output in which the difference in signal levels added in the diagonal direction is negative, in (b) the difference is zero, and in (c) the difference is positive.

In this way, the center of gravity position measurement sensor 80d can directly measure the center of gravity position of the beam spot. While an OEIC is used in this example, the same can be considered when using various cameras. In this case, the image is divided into four pseudo-regions, and the difference in signal level between the diagonal regions of each divided region is calculated to determine which of the above patterns (a) to (c) it corresponds to.

When the line sensor 80b measures the laser beam shape of the reflected light L2 and the center of gravity position measurement sensor 80d measures the center of gravity position of the laser beam, the measurement error generation circuit 90a uses these results to calculate the amount of deviation from the desired laser beam shape and center of gravity position, and adjusts the divergence angle of the beam expander 2a accordingly. This control makes it possible to quickly and accurately change the laser beam spot diameter and spot shape, enabling, for example, printing on the printing object 7 with the desired print thickness, equivalent to that of printing using multiple laser beams. As a result, printing speed can be improved with good visibility.

Figure 7 is a flowchart showing an example of the marking process steps in this embodiment, in which the laser beam shape is measured and laser marking is performed. Since steps S201 to S203 in Figure 7 are the same as steps S101 to S103 in the first embodiment, their explanation will be omitted here, and only steps S204 and onward will be described.

As shown in FIG. 7, in S203, once the print pattern is printed on the print target 7, the position of the divergence angle adjustment element of the beam expander 2a is changed depending on the amount of deviation in the center of gravity detected by the center of gravity measurement sensor 80d. For example, the print control unit 12 instructs the measurement error generation circuit 90a to adjust the position of the divergence angle adjustment element of the beam expander 2a so that the center of gravity of the beam spot becomes pattern (b) shown in FIG. 6 (i.e., the value of the OEIC output signal is ±0). The measurement error generation circuit 90a adjusts the position of the divergence angle adjustment element of the beam expander 2a in accordance with the instruction. The print control unit 12 compares the center of gravity of a predetermined desired laser beam shape with the center of gravity detected by the center of gravity measurement sensor 80d (S204).

The print control unit 12 determines whether the center of gravity position detected by the center of gravity position measurement sensor 80d satisfies predetermined conditions with respect to the center of gravity position of the desired laser beam shape (S205). For example, the print control unit 12 determines whether the center of gravity position detected by the center of gravity position measurement sensor 80d is within a range of ±5% with respect to the center of gravity position of the desired laser beam shape.

If the print control unit 12 determines that the center of gravity position detected by the center of gravity position measurement sensor 80d is within a range of ±5% of the center of gravity position of the desired laser beam shape (S205; Yes), the print control unit 12 identifies the laser beam shape from the brightness of the reflected light L2 detected by the line sensor 80b, as in Example 1. Furthermore, the print control unit 12 calculates the difference in similarity between the identified laser beam shape and the desired laser beam shape (S206).

The print control unit 12 determines whether the difference in similarity between the identified laser beam shape and the desired laser beam shape satisfies a predetermined condition (S207). For example, the print control unit 12 determines whether the difference in similarity between the two is within a range of ±5%.

If the print control unit 12 determines that the difference in similarity between the identified laser beam shape and the desired laser beam shape is within a range of ±5% (S207; Yes), it maintains the position of the divergence angle adjustment element of the beam expander 2a (S208) and proceeds to S209.

On the other hand, if the print control unit 12 determines that the difference in similarity between the identified laser beam shape and the desired laser beam shape is not within the range of ±5% (S207; No), it instructs the measurement error generation circuit 90a to change the position of the divergence angle adjustment element of the beam expander 2a. The measurement error generation circuit 90a fine-tunes the position of the divergence angle adjustment element of the beam expander 2a in accordance with the instruction (S209). After this, the process returns to step S206, and the measurement error generation circuit 90a controls the change of the position of the divergence angle adjustment element so that it is within the above range.

After executing S208, the printing control unit 12 determines whether printing has been completed for all coordinates (x, y) generated in S202 (S210), and if it determines that printing has been completed for all coordinates (x, y) generated in S202 (S210; Yes), it terminates this processing.

On the other hand, if the print control unit 12 determines that printing has not been performed for all of the coordinates (x, y) generated in S102 (S210; No), it returns to S203 and repeats the subsequent processing until printing has been performed for all of the coordinates (x, y).

As shown in FIG. 8, the process shown in FIG. 7 may skip step S209 and return to S204 to perform subsequent processes. In FIG. 8, if the print control unit 12 determines that the difference in similarity between the identified laser beam shape and the desired laser beam shape is not within ±5% (S207; No), the process returns to S204 and performs subsequent processes. With this control, if the difference in similarity between the identified laser beam shape and the desired laser beam shape is not within ±5%, the position of the divergence angle adjustment element of the beam expander 2a can be immediately changed taking into account the deviation amount of the center of gravity position, allowing for faster marking processing.

As described above, the laser marker 2000 in this embodiment performs focus control based on the beam spot of reflected light L2 and the laser light shape, making it possible to automatically adjust the laser light spot position and laser light intensity. This reduces the operational burden and enables high visibility and high-speed printing to be achieved without increasing the size, cost, or lifespan of the device.

Methods for achieving high-speed printing by increasing the printing speed of a laser marker include mechanically increasing the printing speed by increasing the speed of the galvanometer mirror through improvements to the motor, or optically increasing the printing speed by increasing the beam spot diameter of the laser beam. The former method depends on the performance of the motor, which leads to larger and more expensive equipment, so the latter method is preferable. However, even in the latter case, if the printing width is wider than the beam spot diameter, it is necessary to increase the speed of the galvanometer mirror and print multiple lines with the laser beam, which again does not solve the problems of high cost and short life mentioned above.

However, according to this embodiment, the laser beam shape and the laser beam spot position can be directly monitored by the above-mentioned spot monitor function without using a distance sensor as in the conventional technology, thereby making it possible to quickly change the laser beam shape and the laser beam spot position, and by monitoring beams shaped in accordance with the relationship between the print width and the beam spot diameter, such as not only Gaussian but also top hat and ring shapes, it is possible to achieve both high visibility and high speed printing without printing with a laser beam of multiple lines. In other words, to achieve both high visibility and high speed printing, it is necessary to increase the output of the laser beam that serves as the light source, which would result in an increase in the size, cost, and life of the device. However, by shaping the light intensity of the laser beam and changing it from a Gaussian shape to another laser beam shape, it is possible to reduce the required laser power, thereby making it possible to reduce the size and cost of the device.
Example 3
In the second embodiment, the laser beam shape F1 detected by the line sensor is detected, and the center of gravity position of the laser beam is measured, thereby making it possible to adjust the laser beam spot position and the intensity of the laser beam, and the beam is shaped not only into a Gaussian shape but also into a top hat shape, ring shape, etc., depending on the relationship between the print width and the beam spot diameter. Below, a description will be given of cases where beams of these laser beam shapes are shaped and output, and these laser beam shapes are detected and their center of gravity positions are measured.

Figure 9 is a diagram showing an example of the functional configuration of laser marker 3000 in Example 3. Like laser markers 1000 and 2000 in Examples 1 and 2, laser marker 3000 is a device that can print any pattern by irradiating the surface of an object to be printed with laser light of a predetermined wavelength. Below, the same components as those in laser markers 1000 and 2000 in Examples 1 and 2 will be assigned the same reference numerals and their description will be omitted, and the following will mainly describe the configuration that differs from laser marker 1000.

As shown in Figure 9, the laser marker 3000 has the same components as the laser markers 1000 and 2000 in Examples 1 and 2: a laser light generating unit 1, a laser light diameter adjusting unit 2, a laser light branching unit 3, a laser light scanning unit 4 and a laser light scanning unit 5, a laser light emitting unit 6, and a print control unit 12, as well as the same components as the laser marker in Example 2: a laser light measuring unit 80 and a focus control unit 90. Furthermore, in this example, the laser marker 3000 has a laser light shaping unit 13 for shaping the laser light that has passed through the laser light diameter adjusting unit 2 in which the position of the divergence angle adjustment element has been adjusted.

Figure 10 is a diagram showing an example of the physical configuration of the laser marker 3000 shown in Figure 9. As shown in Figure 10, the laser marker 3000 physically has a laser light source 1a, a beam expander 2a, a beam splitter 3a and a quarter-wave plate 3b, an X mirror 4a and a Y mirror 4b, and an fθ lens 6a for focusing, similar to the laser markers 1000 and 2000 in Examples 1 and 2. Furthermore, the laser marker 3000 has a laser beam shaping element 13a. A DOE (Diffractive Optical Element) or an ROE (Refractive Optical Element) can be used as the laser beam shaping element 13a. The laser beam shaping element 13a shapes the laser beam L1 emitted from the laser source 1a so that it has a laser beam shape such as a Gaussian shape, a top hat shape, or a ring shape. Note that the physical configuration of the laser beam measuring unit 80 and the focus control unit 90 is the same as in Example 2, and therefore a description thereof will be omitted here.

In FIG. 10, after passing through the beam splitter 3a, the laser light having the laser light shape shaped by the laser light shape shaping element 13a is detected by the line sensor 80b as the laser light shape of the reflected light L2. For example, the line sensor 80b detects the Gaussian laser light shape F1 as well as other types of laser light shapes shaped by the laser light shape shaping element 13a as the reflected light L2. In this example, in addition to the Gaussian laser light shape F1, it also detects a top-hat laser light shape F2 and a ring-shaped laser light shape F3.

Figure 11 is a flowchart showing an example of the marking process steps in this embodiment, in which the laser beam shape is measured and laser marking is performed. Since steps S301 to S305 in Figure 11 are the same as steps S201 to S205 in Figure 7, their explanation will be omitted here, and only steps S306 and beyond will be described.

As shown in FIG. 11, if the print control unit 12 determines in S305 that the center of gravity position detected by the center of gravity position measurement sensor 80d is within a range of ±5% of the center of gravity position of the desired laser beam shape (S305; Yes), it calculates the least squares error for the laser beam shape of the brightness detected by the line sensor 80b, and outputs the result of fitting the laser beam shape with a predetermined function using the minimum squares error. Furthermore, it calculates the least squares error for a predetermined desired laser beam shape, and outputs the result of fitting the laser beam shape with a predetermined function using the minimum squares error. The print control unit 12 then calculates the error in these output results (S306). The predetermined desired laser beam shape is, for example, a Gaussian, top hat, or ring laser beam shape, as shown in Example 2.

The print control unit 12 determines whether the error calculated in S305 is within a range of ±5% (S307), and if it determines that the error calculated in S305 is within a range of ±5% (S307; Yes), it maintains the position of the divergence angle adjustment element of the beam expander 2a (S308) and proceeds to S310.

On the other hand, if the print control unit 12 determines that the error calculated in S305 is not within the range of ±5% (S307; No), it instructs the measurement error generation circuit 90a to change the position of the divergence angle adjustment element of the beam expander 2a. The measurement error generation circuit 90a fine-tunes the position of the divergence angle adjustment element of the beam expander 2a in accordance with the instruction (S309). After this, the process returns to step S307, and the measurement error generation circuit 90a controls the change of the position of the divergence angle adjustment element so that it is within the above range.

After executing S308, the printing control unit 12 determines whether printing has been completed for all coordinates (x, y) generated in S302 (S310), and if it determines that printing has been completed for all coordinates (x, y) generated in S302 (S310; Yes), it terminates this processing.

On the other hand, if the print control unit 12 determines that printing has not been performed for all of the coordinates (x, y) generated in S302 (S310; No), it returns to S303 and repeats the subsequent processing until printing has been performed for all of the coordinates (x, y).

As shown in FIG. 12, the process shown in FIG. 11 may skip step S309 and return to S304 to perform subsequent processes. In FIG. 12, if the print control unit 12 determines that the error calculated in S305 is not within the ±5% range (S307; No), the process returns to S304 and performs subsequent processes. With this type of control, if the error calculated in S305 is not within the ±5% range, the position of the divergence angle adjustment element of the beam expander 2a can be immediately changed taking into account the deviation amount of the center of gravity position, allowing for faster marking processing.

As described above, the laser marker 3000 in this embodiment performs focus control based on the error between the laser beam shape of the reflected light L2, which is shaped by the laser beam shape shaping element 13a into various laser beam shapes such as Gaussian, top hat, and ring, and these predetermined desired laser beam shapes. This allows the laser beam spot position and laser beam intensity to be automatically adjusted according to each type of laser beam shape, reducing the operational burden and achieving both high visibility and high-speed printing without increasing the size, cost, or lifespan of the device.

As explained above, the laser marker 1000 according to Example 1 is a printing device (e.g., laser marker 1000) that can print any pattern by irradiating a laser beam onto the surface of a printing object (e.g., printing object 7), as explained using Figures 1-3, etc., and includes a laser beam generating unit (e.g., laser beam generating unit 1) that oscillates laser beam, a laser beam diameter adjusting unit (e.g., laser beam diameter adjusting unit 2) that adjusts the beam diameter of the laser beam of a predetermined wavelength oscillated from the laser beam generating unit, a laser beam branching unit (e.g., laser beam branching unit 3) that transmits and reflects the laser beam whose diameter has been adjusted by the laser beam diameter adjusting unit, and The laser beam scanning unit (e.g., laser beam scanning units 4 and 5) two-dimensionally scans the laser beam transmitted through the laser beam branching unit; a laser beam irradiating unit (e.g., laser beam irradiating unit 6) irradiates the object to be printed with the laser beam scanned by the laser beam scanning unit; a laser beam measuring unit (e.g., laser beam measuring unit 8) measures the light reflected from the object to be printed; and a focus control unit (e.g., focus control unit 8) controls the laser beam diameter adjustment unit using the laser beam measuring unit. The focus control unit controls the focal position of the laser beam irradiated onto the object to be printed by the laser beam irradiating unit based on the shape of the reflected laser beam measured by the laser beam measuring unit. As a result, focus control is performed based on the shape of the reflected laser beam, enabling both high visibility and high-speed printing without increasing the size, cost, or life of the device.

As described with reference to Figures 4-8 and other figures, the laser marker 2000 according to Example 2 includes a laser beam shape measurement unit that measures the shape of the laser beam using the laser beam branching unit, and a center of gravity measurement unit that measures the center of gravity of the laser beam (e.g., laser beam measurement unit 80, laser beam shape measurement imaging lens 80a, line sensor 80b, center of gravity position measurement imaging lens 80c, center of gravity position measurement sensor 80d, and half beam splitter 80e). Based on the laser beam shape measurement unit and the center of gravity position measurement unit, the focus control unit controls the divergence angle of the laser beam from the laser beam diameter adjustment unit, and the laser beam irradiation unit controls the focal position of the laser beam irradiated onto the target object. This allows focus control based on the beam spot of the reflected light and the laser beam shape, automatically adjusting the laser beam spot position and laser beam intensity. As a result, high visibility and high-speed printing can be achieved without increasing the size, cost, or lifespan of the device, while reducing the operational burden.

As described with reference to Figures 9-12 and other figures, the laser marker 3000 according to Example 3 includes a laser beam shaping unit (e.g., laser beam shaping unit 13) that shapes and adjusts the shape of the laser beam whose diameter has been adjusted by the laser beam diameter adjustment unit. The focus control unit controls the divergence angle of the laser beam from the laser beam diameter adjustment unit based on the laser beam shape measurement unit and the center of gravity position measurement unit, and the laser beam irradiation unit controls the focal position of the laser beam irradiated onto the object to be marked. This allows focus control based on the error between the laser beam shapes of the reflected light of various shaped laser beams and the predetermined desired laser beam shapes, thereby automatically adjusting the laser beam spot position and laser beam intensity according to each type of laser beam shape. As a result, high visibility and high-speed printing can be achieved without increasing the size, cost, or lifespan of the device, while reducing the operational burden.

The present invention is not limited to the above-described embodiments, and in the implementation stage, the components may be modified and embodied within the scope of the gist of the invention, or multiple components disclosed in the above-described embodiments may be combined as appropriate.

1 Laser light generating unit 2 Laser light diameter adjusting unit 3 Laser light branching unit 4 Laser light scanning unit (x)
5 Laser light scanning unit (y)
6 Laser light irradiation unit 7 Printing object 8, 80 Laser measurement unit 9, 90 Focus control unit 10 Print pattern input unit 11 Print coordinate generation unit 12 Print control unit 13 Laser light shaping unit 1a Laser light source 2a Beam expander 3a Beam splitter 3b 1/4 wavelength plate 4a X mirror 5a for laser light scanning Y mirror 6a for laser light scanning fθ lens 80a for laser light focusing Imaging lens 80b for laser light shape measurement Line sensor 80c Imaging lens 80d for center of gravity position measurement Sensor 80e for center of gravity position measurement Half beam splitter 13a Beam shaping element L1 Laser light L2 Reflected light P1 Laser light spot position

Claims (9)

A printing device capable of printing any pattern by irradiating a printing surface of a printing object with laser light,
a laser light generating unit that oscillates a laser light;
a laser beam diameter adjusting unit that adjusts the beam diameter of the laser beam having a predetermined wavelength oscillated from the laser beam generating unit;
a laser beam branching unit that transmits and reflects the laser beam whose diameter has been adjusted by the laser beam diameter adjusting unit according to polarization;
a laser beam scanning unit that two-dimensionally scans the laser beam that has passed through the laser beam branching unit;
a laser light irradiation unit that irradiates a printing target with the laser light scanned by the laser light scanning unit;
a laser light measuring unit that measures reflected light from the printing object;
a focus control unit that controls the laser beam diameter adjustment unit using the laser beam measurement unit,
the focus control unit controls a focus position of the laser light irradiated onto the printing object by the laser light irradiating unit based on the shape of the reflected laser light measured by the laser light measuring unit.
A printing device characterized by: 2. The printing device according to claim 1,
the laser beam shape measured by the laser beam measuring unit is any one of a Gaussian type, a ring type, and a top hat type;
A printing device characterized by: 2. The printing device according to claim 1,
the laser beam measuring unit includes a laser beam shape measuring unit that measures a shape of the laser beam by the laser beam branching unit, and a center of gravity position measuring unit that measures a center of gravity position of the laser beam,
a focus control unit that controls a divergence angle of the laser beam from the laser beam diameter adjustment unit based on the laser beam shape measurement unit and the center of gravity position measurement unit, and controls a focus position of the laser beam irradiated onto the printing object by the laser beam irradiation unit;
A printing device characterized by: 4. The printing device according to claim 3,
the laser beam shape measured by the laser beam measuring unit is any one of a Gaussian type, a ring type, and a top hat type;
A printing device characterized by: 3. The printing device according to claim 2,
a laser beam shaping unit that shapes and adjusts the shape of the laser beam whose diameter has been adjusted by the laser beam diameter adjusting unit;
a focus control unit that controls a divergence angle of the laser beam from the laser beam diameter adjustment unit based on the laser beam shape measurement unit and the center of gravity position measurement unit, and controls a focus position of the laser beam irradiated onto the printing object by the laser beam irradiation unit;
A printing device characterized by: 4. The printing device according to claim 3,
the laser beam shape measured by the laser beam measuring unit is any one of a Gaussian type, a ring type, and a top hat type;
A printing device characterized by: A printing method performed by a printing device capable of printing any pattern by irradiating a printing surface of a printing object with laser light, comprising:
The laser light generating unit oscillates a laser light,
a laser beam diameter adjusting unit that adjusts the beam diameter of the laser beam having a predetermined wavelength oscillated from the laser beam generating unit;
a laser beam branching unit that transmits and reflects the laser beam whose diameter has been adjusted by the laser beam diameter adjusting unit according to the polarization of the laser beam;
a laser beam scanning unit that two-dimensionally scans the laser beam that has passed through the laser beam branching unit;
a laser light irradiation unit irradiating the laser light scanned by the laser light scanning unit onto the printing object;
a laser light measuring unit that measures reflected light from the printing object;
a focus control unit that controls the laser beam diameter adjustment unit using the laser beam measurement unit;
the focus control unit controls a focus position of the laser light irradiated onto the printing object by the laser light irradiating unit based on the shape of the reflected laser light measured by the laser light measuring unit.
A printing method characterized by: 8. The printing method according to claim 7,
the laser beam measuring unit includes a laser beam shape measuring unit that measures a shape of the laser beam by the laser beam branching unit, and a center of gravity position measuring unit that measures a center of gravity position of the laser beam,
a focus control unit that controls a divergence angle of the laser beam from the laser beam diameter adjustment unit based on the laser beam shape measurement unit and the center of gravity position measurement unit, and controls a focus position of the laser beam irradiated onto the printing object by the laser beam irradiation unit;
A printing method characterized by: 9. The printing method according to claim 8,
a laser beam shaping unit that shapes and adjusts the shape of the laser beam whose diameter has been adjusted by the laser beam diameter adjusting unit;
a focus control unit that controls a divergence angle of the laser beam from the laser beam diameter adjustment unit based on the laser beam shape measurement unit and the center of gravity position measurement unit, and controls a focus position of the laser beam irradiated onto the printing object by the laser beam irradiation unit;
A printing method characterized by: