JP2005186078A - Laser marking device and laser marking method - Google Patents

Abstract

A laser capable of marking an image having a contrast that is inferior to that of an original image by adjusting a dot diameter when marking an image read from a scanner or the like on a material to be marked. A marking device and a laser marking method are provided.
Wavelength selection devices including a laser oscillation device that emits spherical dot-shaped laser light and a plurality of wavelength conversion devices that respectively convert wavelengths of laser light incident from the laser oscillation device to different wavelengths. Further, the present invention relates to a laser marking device including a condensing lens 59 that condenses laser light on a marking target material W. The wavelength selection devices 48a to 48c include a controller 41, and are formed so as to be able to select whether one of the wavelength switching devices 48a to 48c is arranged at the incident position of the laser light based on the wavelength information of the computer. Become.
[Selection] Figure 3

Description

  The present invention relates to a laser marking device and a laser marking method, and more particularly, to a laser marking device and a laser marking method for adjusting a density of an image to be marked by changing a dot diameter by changing a laser wavelength and a condenser lens. .

2. Description of the Related Art Conventionally, a technique for marking a two-dimensional code, a character, a logo mark, an image, or the like with a laser marking device is known.
However, when performing laser marking, only colorless and colored cells can be used to express only black and white, and it has been difficult to mark a photographic image or the like having a density of light and dark.
That is, even if a photographic image or the like is simply binarized into black and white and marking is performed, it is difficult to express a density gradation of the photographic image or the like.

  In order to solve such problems and control the density of marking, a technique for controlling the number of marking operations has been developed (for example, Patent Document 1).

JP 2003-001442 A (column 5, line 47 to column 9, line 19, FIG. 5)

Japanese Patent Application Laid-Open No. H10-228561 describes that in the laser marking, the density of the marking is controlled as follows.
That is, a laser marking control method for controlling the number of times of laser irradiation, adjusting the degree of alteration / discoloration of the material to be marked, and expressing the three shades of white gray, gray and brown by marking is described. ing.
According to this marking method, if the number of times of laser irradiation is increased, the color of the marking becomes brown, and if the number of times of laser irradiation is decreased, the color of the marking changes from gray to white-gray.

In the above conventional laser marking control method, it is possible to adjust the marking density to some extent, but because the number of times of laser irradiation increases in the dark marking part, there is a possibility of generating a damage mark such as a crack in the material to be marked. In view of durability, there is a problem in that it is difficult to mark a material to be marked such as glass that is easily broken.
Further, according to the density control based on the number of times of laser irradiation, it is difficult to finely adjust the density, and it is difficult to mark an image that requires detailed density adjustment, such as a photographic image.

An object of the present invention is to solve the above-mentioned problems, and when marking an image read from a scanner or the like on a marking target material, the dot diameter is adjusted, thereby fading the original image. It is an object of the present invention to provide a laser marking apparatus and a laser marking method capable of marking a non-image.
Another object of the present invention is to incorporate a plurality of wavelength converters into a laser marker and to take out an appropriate laser wavelength for marking a dot having a required dot diameter by automatic control, and It is to provide a laser marking method.

According to the first aspect of the present invention, there is provided a laser oscillation device that emits spherical dot-shaped laser light and a plurality of wavelengths that convert wavelengths of the laser light incident from the laser oscillation device into different wavelengths. A wavelength selection device including a conversion device; and a condensing lens that condenses the laser light on a marking target material. The wavelength selection device includes wavelength conversion device switching means, and the wavelength switching means includes the laser. This can be solved by forming whether or not one of the plurality of wavelength switching devices is arranged at the light incident position.
Since it is constituted in this way, it becomes possible to switch and use laser beams of a plurality of wavelengths with one laser marking device.
If the wavelength of the laser beam applied to the object to be marked is different, dots having different diameters are formed on the object to be marked.
For this reason, if the wavelength is switched by the wavelength converter, it is possible to mark dots having different dot diameters.
In addition, since the wavelength of the laser beam used differs depending on the type of the object to be used, it has been necessary to have a plurality of marking devices. However, according to the laser marking device of the present invention, it is not necessary to provide a plurality of laser marking devices because a single marking device can switch and use laser beams having a plurality of wavelengths.

At this time, a control means for creating marking information for marking the material to be marked is provided, and the wavelength conversion device switching means is driven and controlled in accordance with irradiation laser wavelength information as marking information created by the control means to control the laser. It is preferable that the wavelength conversion device to which light is incident is switched.
Since it is constituted in this way, it becomes possible to automatically switch the wavelength converter according to the marking information created by the control means.

  Further, the wavelength selection device is a device that switches the wavelength conversion device and converts the wavelength of the laser light into laser light of any one of the first to fourth harmonics, It is preferable that the dot diameter formed on the marking target material is controlled in a range of 1 μm or more and 70 μm or less by converting the wavelength of the laser beam with a wavelength selection device.

According to the fourth aspect of the present invention, there is provided a laser oscillation device that emits spherical dot-shaped laser light, and a plurality of collectors that condense the laser light incident from the laser oscillation device onto a marking target material. A condensing lens selection device comprising an optical lens, the condensing lens selection device comprising condensing lens switching means, wherein the condensing lens switching means comprises one of the plurality of condensing lenses. This can be solved by selectively disposing an optical lens at a position where the laser beam is incident.
Since it is comprised in this way, it becomes possible to switch and use several condensing lenses with one laser marking apparatus.
Even when laser beams having the same wavelength are used, dots having different diameters are formed on the object to be marked if the thickness of the condenser lens is different.
For this reason, if the condensing lens is switched by the condensing lens selection device, it becomes possible to mark dots having different dot diameters.

At this time, a control means for creating marking information for marking the material to be marked is provided, and the laser is controlled by driving the condensing lens switching means in accordance with irradiation laser wavelength information as marking information created by the control means. It is preferable that the condenser lens to which light is incident is switched.
If comprised in this way, it will become possible to switch a condensing lens automatically according to the marking information produced by the control means.

According to the invention according to claim 6, the above-described problem is that a laser oscillation device that emits spherical dot-shaped laser light and a plurality of wavelengths that convert wavelengths of the laser light emitted from the laser oscillation device to different wavelengths, respectively. A wavelength selection device including a wavelength conversion device, and a condensing lens selection device including a plurality of condensing lenses for condensing the laser light whose wavelength has been converted by the wavelength selection device on a marking target material, The wavelength selection device includes a wavelength conversion device switching unit, and the wavelength switching unit is formed so as to be able to select whether or not one of the plurality of wavelength switching devices is arranged at an incident position of the laser beam. The condensing lens selection device includes condensing lens switching means, and the condensing lens switching means selectively disposes one condensing lens of the plurality of condensing lenses at a position where the laser light is incident. You It is solved by.
Since it is constituted in this way, it becomes possible to switch and use laser light of a plurality of wavelengths and a plurality of condensing lenses with one laser marking device.
If the wavelength of the laser beam applied to the object to be marked is different, dots having different diameters are formed on the object to be marked.
Similarly, even when laser beams having the same wavelength are used, dots having different diameters are formed on the object to be marked if the thickness of the condenser lens is different.
For this reason, it is possible to mark dots with different dot diameters by switching the wavelength with the wavelength conversion device, and marking dots with different dot diameters by switching the condensing lens with the condensing lens selection device. It becomes possible.
Therefore, by controlling both the wavelength selection device and the condenser lens selection device in combination, it becomes possible to form dots with various diameters, and there is no need to provide a plurality of laser marking devices.

At this time, it is provided with a control means for creating marking information for marking the material to be marked, and in accordance with the irradiation laser wavelength information as the marking information created by the control means, the wavelength conversion device switching means is driven and controlled to perform laser It is preferable that the wavelength conversion device to which light is incident is switched, and the condensing lens switching unit is driven and controlled to switch the condensing lens to which the laser light is incident.
If comprised in this way, according to the marking information produced by the control means, it will become possible to switch a wavelength converter and a condensing lens automatically.

Further, at this time, the wavelength selection device is a device that switches the wavelength conversion device and converts the wavelength of the laser light into laser light of any wavelength from the first harmonic to the fourth harmonic,
The condensing lens selection device is a device for switching the plurality of condensing lenses to narrow down the laser light, wherein the wavelength selection device converts the wavelength of the laser light, and further converts the wavelength of the laser light. And the dot diameter formed on the marking target material is controlled in the range of 0.1 μm or more and 50 μm or less by narrowing down with the condensing lens selected by the condensing lens selection device. Is preferred.

Further, at this time, the control device includes time control means for controlling a laser irradiation delay time, and the dot mass irradiated to the object to be marked is changed by controlling the laser irradiation delay time by the time control means. It is suitable if it is constituted so as to be.
With this configuration, the dot mass can be changed, so that the pressure applied to the marking material can be controlled when the marking material is irradiated with laser light. Therefore, since the laser irradiation delay time can be changed according to the physical properties of the marking target material, the room for selecting the marking target material is widened.
At this time, the laser irradiation delay time is controlled in the range of 1 to 100000 μsec.

According to the invention according to claim 11, the subject is an image information acquiring step for capturing image information, an information acquiring step for acquiring at least density information and coordinate information from the captured image information, and the density A dot diameter information acquisition step for calculating dot diameter information indicating the dot diameter of a dot to be marked based on the information, and wavelength information for setting wavelength information indicating the wavelength of the laser beam to be irradiated based on the dot diameter information An acquisition step, a condensing lens information setting step for setting condensing lens information indicating which of the condensing lenses to use based on the wavelength information, the coordinate information, and the wavelength A marking information setting step for setting marking information from the information and the condenser lens information, and a plurality of wavelength converters according to the wavelength information, and changing the wavelength of the laser light. A wavelength conversion device switching step of controlling the wavelength selection device to switch the wavelength conversion device, and a condensing lens comprising a plurality of condensing lenses for condensing the laser light on the marking target material according to the condensing lens information This is solved by a laser marking method comprising: a condensing lens switching step of switching a condensing lens by controlling a selection device; and a laser marking step of irradiating a marking target material with laser light according to the coordinate information.
When configured in this manner, the wavelength selection device and the condensing lens selection device can be controlled to adjust the dot diameter of the dots to be marked, and various markings can be applied.

According to the present invention, when marking a dark image such as a photographic image by changing the dot diameter of the dot to be marked, an image having a light and shade equivalent to the original photographic image is marked on the marking target material. It becomes possible to do.
In other words, by changing the dot diameter of the marked dots, it is possible to change the dot density in a predetermined cell, so that an image having the same density as gray scale printing, which is a general printing technique, can be obtained. Marking material can be marked.
Therefore, for example, when marking an image having complex density information such as a photographic image, a clearer marking image can be obtained, and the face matching accuracy is improved. The marking method according to the present invention can be applied to required products.

In addition, unlike the prior art, it is not necessary to irradiate the laser beam many times, so that the possibility of occurrence of a crack or the like occurring at the laser irradiation position is reduced.
Furthermore, according to the present invention, since dot marking is employed instead of vector marking as the laser marking method, fracture marks such as cracks caused by the radiation pressure of the laser light are contained in the inner wall surface of the dot, Destruction marks such as cracks generated outside the laser irradiation position can be minimized.

Further, according to the present invention, a plurality of wavelength conversion devices are provided in the laser marker, and the wavelength of the laser light is converted to an appropriate wavelength by automatically switching to an appropriate wavelength conversion device according to the dot diameter of the dot to be marked. And marking.
For this reason, it is not necessary to provide a plurality of laser marking devices for each wavelength of the oscillated laser beam, and it is not necessary to manually replace the wavelength converter every time the wavelength of the laser beam is changed.
In addition, since the wavelength converter is automatically switched based on the wavelength information transmitted from the control means, it is possible to finely change the wavelength, and marking multiple dots with different dot diameters with a single marking operation Is possible.

  Furthermore, in the present invention, it is possible to mark dots having different dot diameters, and therefore, when generating a two-dimensional code, compared to when creating a two-dimensional code with dots having a single dot diameter. Thus, more information can be included in the two-dimensional code.

  Further, according to the present invention, the dot diameter data for each dot can be calculated from the density information of the read image data, and the wavelength converter can be automatically switched by setting the laser wavelength from the dot diameter data. Therefore, precise adjustment of the dot diameter is possible, and convenience is improved.

Furthermore, in the present invention, there is provided a condensing lens selection device in which a plurality of condensing lenses having different thicknesses are arranged in the laser marker so as to be switchable.
If the thickness of the condensing lens is changed, the focal position changes, so that the dot diameter to be marked can be changed. In this way, it is possible to finely adjust the dot diameter by switching the condensing lens by the condensing lens switching device.
Therefore, in the present invention, basically, it is possible to adjust the dot diameter by converting the wavelength by the wavelength converter, and further finely adjust the dot diameter by the condenser lens switching device.
Therefore, it is possible to precisely control the dot diameter to be marked, and it is possible to mark an image that is inferior to the original image when marking an image having a light and shade such as a photographic image.

Further, in the present invention, since the dot marking method is adopted, the generation of fracture marks such as cracks that damage the object to be marked is suppressed as compared with the marking by the conventional vector marking method.
That is, the direction in which the radiation pressure is generated is different between the dot marking method and the vector marking method. With the marking in the dot marking method, it is possible to contain the occurrence of fracture marks such as cracks on the inner wall surface of the dot.
Therefore, since the influence given to the to-be-marked body surface by marking decreases, durability of the to-be-marked body to which marking was given becomes high.

Furthermore, in the present invention, it is possible to adjust the laser irradiation delay time.
Since the dot mass is changed by adjusting the laser irradiation delay time, it is possible to adjust the radiation pressure.
Therefore, it is possible to mark various objects to be marked having different strengths and physical properties such as glass, metal, and resin.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The members, arrangements, configurations, and the like described below do not limit the present invention and can be variously modified within the scope of the gist of the present invention.

FIG. 1 to FIG. 15 are diagrams showing an embodiment of the present invention. FIG. 1 is an explanatory diagram showing the overall configuration of a laser marking device, FIG. 2 is an explanatory diagram showing the configuration of a data control unit, and FIG. FIG. 4 is an explanatory diagram illustrating the configuration of the wavelength selection device, FIG. 5 is an explanatory diagram illustrating the principle of the wavelength conversion device, FIG. 6 is an explanatory diagram illustrating the configuration of the condenser lens device, and FIG. 7 is a laser. FIG. 8 is an explanatory diagram showing a change in the dot diameter depending on the wavelength of the laser beam, FIG. 9 is an explanatory diagram showing a marking difference due to a difference in dot step size, and FIG. 10 is a two-dimensional code. FIG. 11 is an explanatory diagram showing the marking state of characters, FIG. 12 is an explanatory diagram showing the direction of generation of radiation pressure when the laser light is incident on the object to be marked, and FIG. From marking body FIG. 14 is an explanatory diagram showing the generation state of cracks in the dots, and FIG. 15 is an explanatory diagram showing the crack generation state in dot marking and the crack generation state in vector marking. is there.
Laser marking according to the present embodiment is performed by a dot marking method. The dot marking method is a method in which marking is performed by forming a plurality of substantially hemispherical marking marks on the surface of an object to be marked.

FIG. 1 is an explanatory diagram showing the overall configuration of the laser marking apparatus according to the present embodiment.
S shown in FIG. 1 indicates the laser marking device according to the present embodiment.
This laser marking device S is suitably used for marking a marking pattern such as characters, figures, symbols, images, etc. on an object to be marked, and mainly includes a scanner 10, a tablet 20, a computer 30, and a laser marker 40. It is a component.

The scanner 10 is a marking pattern input unit.
The scanner 10 reads analog data related to a marking pattern such as characters, figures, symbols, and images taken on a sheet of paper with an internal sensor, converts the read analog information into digital information, and outputs the digital information. .
The tablet 20 is a marking pattern input unit similar to the scanner 10.
The tablet 20 is configured so that analog information can be input by entering a marking pattern such as characters, figures, symbols, and the like on the plate-like input unit 21 using a pen 22. The input analog information is converted into digital information and output.
In addition to the scanner 10 and the tablet 20, the marking pattern input means according to the present invention may be constituted by a CCD camera, a digital camera, a video camera, a portable terminal, etc. The keyboard 32 and the mouse 33 may be provided.

The computer 30 as the control means generates a marking pattern on the object to be marked W based on the digital data output from the scanner 10 and the tablet 20, and operates a laser marker 40 to be described later using the generated marking data. Is.
The computer 30 in the present embodiment is a personal computer and includes a display unit 31, a keyboard 32, a mouse 33, and the like.
As shown in FIG. 2, the personal computer main body 34 includes a CPU 35 as a data calculation / control processing device and a storage unit 36 for storing various data. The storage unit 36 includes a ROM 36a, a RAM 36b, and a hard disk as storage devices. 36c and an input / output unit 37.

The ROM 36a stores a control program for operating the CPU 35, and the RAM 36b is used as a work area for temporarily storing data.
The hard disk 36c stores font data created in advance (for example, general font data such as Mincho and Gothic), marking pattern data related to characters, figures, symbols, and the like.
The hard disk 36c stores parameter information. The parameter information sets conditions for performing laser marking.
These conditions include laser frequency, output, number of prints, beam diameter, irradiation time, and the like. These conditions are read by the CPU 35 when performing laser marking.
The input / output unit 37 inputs and outputs information between the computer 30 and an external device. The calculation result in the CPU 35 is transmitted to the laser marker 40 via the input / output unit 37.

In the present embodiment, the computer 30 and the laser marker 40 are directly connected by a cable. However, the computer 30 and the laser marker 40 may be connected via an information communication network such as a wireless LAN or the Internet.
If comprised in this way, it will become possible to transmit the instruction | indication and data from another place or a remote place, and to control the laser marker 40. FIG.
For example, a configuration in which a computer 30 is installed in a control room and the like, a laser marker 40 is installed in a work room, a configuration in which the computer 30 is installed in the head office, and the laser marker 40 is installed in factories in various places is possible. Become.

The laser marker 40 is classified into a YAG laser, a CO ₂ laser, a YVO ₄ laser, a UV laser, a green laser, and the like depending on the type of laser that oscillates.
In the present embodiment, a configuration in which the computer 30 and the laser marker 40 are installed on a one-to-one basis is shown. However, a plurality of laser markers 40 are connected to the computer 30 and are appropriately selected according to the material to be marked. The laser marker 40 that emits a simple laser beam may be selected.

As an example of the laser marker 40, FIG. 3 shows the configuration of a YAG laser device used in this embodiment.
The laser marker 40 includes a controller 41, a YAG laser oscillator 50, a galvanometer mirror 47, and a condenser lens selection device 59 as main components.
The controller 41 is for driving and controlling each device of the laser marker 40.
The controller 41 drives and controls each device of the laser marker 40 based on information output from the computer 30.

The YAG laser transmitter 50 is a device for oscillating laser light used for marking.
The YAG laser transmitter 50 includes a Q switch element 43, a full-surface reflecting mirror 51, an internal aperture 52, a lamp house 53, an internal shutter 44, and an output mirror 54.
The Q switch element 43 is a device for obtaining pulsed laser light having an extremely high peak output (peak value).
The laser beam output from the lamp house 53 is amplified and adjusted by the internal aperture 52 while reciprocating between the total reflection mirror 51 and the output mirror 54, and is pulsed by the Q switch element 43 at a predetermined interval.

The wavelength selection device 48 is a device for switching and selecting the wavelength conversion devices 48a to 48c.
In the wavelength selection device 48, wavelength conversion devices 48a to 48c are arranged to be switchable.
Based on the wavelength information transmitted from the computer 30, the wavelength converters 48 a to 48 c are switched to those that can output an appropriate wavelength by the controller 41.

FIG. 4 is an explanatory diagram showing the mechanism of the wavelength selection device 48.
The wavelength selection device 48 includes wavelength conversion devices 48a to 48c.
The wavelength converters 48a, 48b, and 48c respectively convert the first harmonic into the second harmonic, the third harmonic, and the fourth harmonic.
In each of the wavelength conversion devices 48a to 48c, the angle formed by the wavelength conversion device 48a, the rotation shaft 48e, and the wavelength conversion device 48b and the angle formed by the wavelength conversion device 48b, the rotation shaft 48e, and the wavelength conversion device 48c are substantially perpendicular. In this way, it is fixed to the substrate 48d.
The substrate 48d is a circular plate-like body, and a rotation shaft 48e is fixed at the center, and the rotation shaft 48e can be driven to rotate by a motor (not shown).
A motor (not shown) is controlled by the controller 41.

For example, when the wavelength conversion device 48c is used to convert the wavelength, as shown in FIG. 4A, the substrate 48d is controlled to stop at a position where the laser light passes through the wavelength conversion device 48c. .
Further, when it is not necessary to convert the wavelength, the substrate 48d is controlled to stop at a position where the laser light passes through a place where the wavelength converters 48a to 48c do not exist, as shown in FIG. 4B. The
However, the configuration of the wavelength selection device 48 is not limited to this configuration.
In the present embodiment, the substrate 48d is a rotatable circular plate-like body, but may be formed in a rotatable cylindrical shape, or may be formed in a plate shape movable in the horizontal direction. .

FIG. 5 is an explanatory diagram showing the principle of the wavelength converter 48a. The wavelength conversion devices 48b and 48c also have the same principle, and the types of nonlinear crystals used are different.
The laser light before wavelength conversion incident on the wavelength conversion device 48 a is incident on the nonlinear crystal 490.
When the nonlinear crystal 490 is irradiated with strong light such as laser light, polarization occurs in proportion to the intensity of the electric field, that is, the square of the intensity of the light, or the third power of the light, and is twice or 3 times the angular frequency of the incident light. It is a substance that generates a high frequency such as double, and a nonlinear crystal 490 having a different atomic structure is used depending on the wavelength to be converted.
When the laser beam passes through the nonlinear crystal 490, a nonlinear phenomenon called wavelength conversion occurs.
As the nonlinear crystal 490, a known nonlinear crystal is used, and for example, KTP, KDP, DKDP, BBO or the like is used.
The laser light that has passed through the nonlinear crystal 490 and whose wavelength has changed is adjusted by the filter 491 and emitted from the wavelength selection device 48.

The galvanometer mirror 47 is a mirror for determining the plane coordinate position on the object to be marked W to which the laser beam is finally irradiated, and is driven and controlled by the controller 41 based on the coordinate information transmitted from the computer 30. .
A motor is used as a drive source for the carbano mirror 47.

The condenser lens selection device 59 is a device for switching the condenser lenses 59 a to 59 c based on the condenser lens information transmitted from the computer 30.
The condensing lenses 59a to 59c are lenses for condensing the laser light reflected by the galvanometer mirror 47 and forming a focal point of the laser light.
As the condenser lens, a plurality of fθ lenses 59a, 59b, and 59c having different thicknesses are disposed so as to be switchable.
In the present embodiment, the thicknesses of the fθ lenses 59a, 59b, and 59c are 10 mm, 20 mm, and 30 mm, respectively.
The fθ lens is a lens designed so that the focal point when incident on the lens at an angle θ from the optical axis is on the same plane as the plane that focuses the light passing through the optical axis.
However, the lens used as the condenser lens is not limited to the fθ lenses 59a, 59b, and 59c, and a single lens or an aspheric lens may be used.
In this case, marking may be performed while correcting the focal position using a known linear translator.

FIG. 6 is an explanatory view showing the mechanism of the condensing lens device 59.
FIG. 6 is an explanatory diagram when the condenser lens device 59 is viewed from above, and the laser light passes from the top surface to the bottom surface in FIG.
The condenser lens device 59 includes condenser lenses 59a to 59c.
Each condenser lens 59a to 59c is fixed to the substrate 59d.
The substrate 59d is a rectangular plate-like body, and is engaged with a slide groove (not shown) that guides the movement in the horizontal direction. The substrate 59d can be driven in the horizontal direction by a motor (not shown).
A motor (not shown) is controlled by the controller 41.

For example, when it is desired to collect light using the condensing lens 59a, the condensing lens 59a is controlled to stop at the laser beam passage position 59e as shown in FIG.
Further, in the state of FIG. 6A, the substrate 59d can move horizontally in the X direction, and when switching to the condenser lens 59b or the condenser lens 59c, drive control is performed in the X direction.
When it is desired to collect light using the condensing lens 59b, the substrate 59d is controlled to stop in the state shown in FIG. When switching from this state to the condensing lens 59c, the substrate 59d is driven and controlled in the X direction, and when switching to the condensing lens 59a, the substrate 59d is driven and controlled in the Y direction.
However, the configuration of the condensing lens device 59 is not limited to this configuration.
In the present embodiment, the substrate 59d is formed in a rectangular plate shape that can be driven in the horizontal direction.
You may form in the circular plate shape which can rotate.

The laser beam from the laser marker 40 configured in this way follows the following locus.
That is, the laser beam pulse-output from the YAG laser transmitter 50 passes through the external shutter 45 and enters the wavelength selection device 48.
The laser beam emitted from the wavelength selection device 48 having a changed wavelength is changed in optical path by the leveling mirror 56, narrowed by the aperture 55, and then expanded by the Galileo expander 57. Further, after the beam diameter is adjusted by the aperture 58, the beam is attenuated by the attenuator 46 and then proceeds toward the galvanometer mirror 47.
The laser beam reflected by the galvanometer mirror 47 enters the condenser lens device 59, is condensed by any one of the condenser lenses 59a to 59c, and is irradiated onto the object to be marked W.

  With reference to FIG. 7, a method for marking a marking target object W with a marking pattern set and input by a user using the laser marking device S having the above-described configuration will be described.

The process flow of the laser marking method is shown in FIG.
First, in the data generation step, bitmap data about a marking pattern to be marked on the object to be marked W is acquired (step S1).
That is, when the user inputs analog data to the scanner 10 or the tablet 20, the analog data is read by the scanner 10 or the tablet 20, converted into digital data, and output to the control unit 30. The output digital data is stored in the computer 30 in a bitmap file format.

Note that bitmap data may be obtained by writing characters or graphics on the bitmap file using the mouse 33.
Further, by inputting characters using the keyboard 32, font data and characters stored in the hard disk 36c may be read out, and bitmap data may be acquired from the font data and character data.
At this time, commercially available font data (account flow, sumo characters, calligraphy characters, etc.) data may be installed in the computer 30, and bitmap data may be acquired from these font data.
Of course, the original font created by the user's handwriting can be taken in by the scanner 10 or the tablet 20 to obtain the bitmap data.

Next, marking conditions are set (step S2).
Here, when marking characters, two-dimensional codes, logo marks, etc., the “laser parameters” are the wavelength of the laser to be irradiated, the beam diameter, the frequency of the Q switch element, the power value, the power, the dot irradiation time, the laser. Set marking conditions such as irradiation delay time and number of markings. In addition, when inputting characters, it is possible to set font size, position, character spacing, bold, italic characters, etc. as “character parameters”.
However, when marking an image having density information captured by the scanner 10, the marking condition corresponding to the laser parameter is automatically calculated and determined by the computer 30.

Then, based on the conditions set in step S2, marking data for dot marking of characters, two-dimensional codes, images, etc. is generated from the bitmap data stored in the computer 30 (step S3).
That is, the presence or absence of pattern input for each pixel is detected in the bitmap file. At this time, the presence / absence of pattern input is detected from the upper right side to the upper left side of the bitmap file. If it goes to the upper left side, it goes down one step and goes to the right side. Do. In this way, the operation is alternately performed from right to left, from top to bottom, and from left to right.
Further, the density of the marking pattern is recognized as a gray scale, and a dot diameter corresponding to the density is calculated and set for each pixel.
The dot diameter is the value of the dot diameter.

Here, it is detected whether each pixel is black or white, and if it is black, it is assumed that there is a pattern input, and the dot diameter of the dot marked on each pixel is detected. If the pixel is white, it is assumed that there was no pattern input.
Then, the two-dimensional coordinate data of the marking pattern is acquired based on the pattern-input pixels, the two-dimensional coordinate data acquired in this way is acquired, and the two-dimensional coordinate data of the dots marked for each pixel, dot Based on the diameter and each condition set in step 2, dot marking data for dot marking is formed.
However, for image data having density information captured from the scanner 10, wavelength information and condenser lens information are determined based on dot diameter information calculated from the density information, and two-dimensional coordinate information and Wavelength information and condenser lens information are set.

A photographic image or the like captured by a scanner is expressed as a set of dots having different diameters.
In the conventional printing technique, gray scale is expressed by adjusting the density of halftone dots. That is, a portion where the density of halftone dots is high is dark, and a portion where the density of halftone dots is low is light.
In this embodiment, it is possible to express a precise gray scale by adjusting the dot density by changing the dot diameter by using the dot by laser marking as a halftone dot and changing the dot diameter.
That is, the color becomes darker by increasing the diameter of dots existing in the same area, and the color becomes lighter by decreasing the dot diameter.
Therefore, it is possible to express subtle shades of color by changing the dot diameter.
The dot diameter can be adjusted by controlling the wavelength of the laser beam and the condenser lens.

Thus, by adjusting the dot diameter of the marked dots, it is possible to express an image that is inferior to the color image by marking.
Therefore, the collation of photographic images is improved, and the laser marking method according to this embodiment can be applied to products that require high image collation such as employee ID cards and various certificates.

Next, the process proceeds from the data generation process to the laser marking process.
First, in the laser marking process, it is determined at which position of the marking target W a character, figure, image, etc. is to be marked, and the marking target W is aligned in the marking region (step S4).
Then, using the laser marker 40, the marking object W is irradiated with laser light to form a marking pattern composed of an array of dots on the marking object W (step 5).
That is, the dot marking data formed by the computer 30 is transmitted to the controller 41 of the laser 40.

The controller 41 receives dot marking data.
Based on the dot marking data, the controller 41 controls the ultrasonic Q switch element 43, the internal shutter 44, the external shutter 45, the attenuator (light attenuator) 46, the wavelength selection device 48, the condensing lens device 59, and the carbano mirror 47. Control.
Thereby, the laser beam is irradiated onto the object to be marked W, and dot marking is performed according to the data for dot marking.
A marked character, figure, image, or the like is an aggregate of a plurality of dots.

An explanatory diagram showing the state of the dot diameter for each wavelength in this embodiment is shown in FIG.
FIG. 8 schematically shows a state immediately before the laser light is incident on the object to be marked W. FIG.
As shown in FIG. 8, in the dot marking method in this embodiment, laser light is irradiated in a state where spherical dots are connected.
The wavelength of the laser light is converted to a required wavelength by the wavelength selection device 48 and is irradiated onto the object to be marked W.
In this embodiment, the wavelength of the laser beam that can be applied to the object to be marked W is 1064 nm as the first harmonic, 532 nm as the second harmonic, 354 nm as the third harmonic, and 266 nm as the fourth harmonic. There are four types.

The size of the dot increases as the wavelength of the irradiated laser beam increases, and decreases as the wavelength of the irradiated laser beam decreases. That is, the diameter of the first harmonic dot 61 is the maximum, and the diameter of the dot decreases in the order of the second harmonic dot 62, the third harmonic dot 63, and the fourth harmonic dot 64.
Accordingly, if the wavelength conversion devices 49a to 49c are switched by the wavelength selection device 48, the wavelength is converted, and the dot diameter of the dots formed on the object to be marked W can be changed.
In addition, by converting the wavelength of the laser light in this way, the diameter of the dots formed on the object to be marked W can be controlled in the range of 1 μm to 70 μm.

In the present embodiment, a condensing lens selection device 59 is provided.
By further narrowing down the laser beam with the condensing lens selection device 59, the diameter of the dots formed on the object to be marked W can be controlled in the range of 0.1 μm to 50 μm.
As described above, in the condensing lens device 59, three kinds of condensing lenses 59a to 59c having thicknesses of 10 mm, 20 mm, and 30 mm are installed in a switchable manner. For this reason, it is possible to finely adjust the diameter of the dots formed on the object to be marked W by slightly changing the focal position of the laser light by switching the condenser lens.
Thus, by providing the condensing lens selection device 59, it becomes possible to perform finer dot diameter control than when the dot diameter is controlled only by the wavelength selection device 48.

An example of the marking state of the dots in this embodiment is shown in FIG.
FIG. 9 shows a simplified state in which dots having different dot diameters are marked on the object to be marked W. FIG.
In the present embodiment, it is possible to adjust the degree of dot overlap.
The marking parameter includes a field for inputting “dot overlap”.
In the marking parameter dot overlap column, “0”, “1”, “2”, and “3” can be set.

If “0” is set, the dot overlap state is ignored and marking is performed according to the set step size. The step size refers to the center distance between adjacent dots.
If “1” is set, marking is performed so that adjacent dots touch each other.
Since the two-dimensional coordinate information and the dot diameter information are set for each dot, the dot diameter of adjacent dots is calculated from the two-dimensional coordinates, and the sum of both radii a1 + a2 is set as the step size of both. Mark.
As a result, even when the dot diameters of the dots are different, marking is performed in a state where adjacent dots are in contact with each other as shown in FIG.

If “2” is set, marking is performed in a state where adjacent dots are separated.
The creation of the marking data is the same as when “1” is set. In this case, the step size between adjacent dots is obtained by adding the separation distance b3 to the sum b1 + b2 of the radii of both dots.
The separation distance b3 indicates the distance between adjacent dots.
The separation distance b3 may be set constant, or may be configured so that the user can set it as a marking parameter.
As a result, even when the dot diameters of the dots are different, as shown in FIG. 7B, marking is performed in a state where adjacent dots are separated by a certain distance.

If “3” is set, marking is performed in a state where adjacent dots overlap.
The creation of the marking data is the same as when “1” is set. In this case, the step size of adjacent dots is obtained by subtracting the approach distance c3 from the sum c1 + c2 of the radii of both dots.
The approach distance c3 indicates a distance at which adjacent dots overlap.
This approach distance may be set constant, or may be configured so that the user can set it as a marking parameter.
As a result, even when the dot diameters of the dots are different, as shown in FIG. 7C, marking is performed in a state where adjacent dots overlap each other for a certain distance.
If the difference obtained by subtracting the approach distance c3 from the sum of both dots becomes a negative number, the two-dimensional coordinates are reversed, and an error is displayed.

An example of the marking state of the two-dimensional code in this embodiment is shown in FIG.
The two-dimensional code is a code that displays data representing a light and dark pattern by a combination of white and black cells arranged in a matrix.
In the dot marking method in the present embodiment, a circular dot is laser-marked vertically and horizontally into n × n or n × m (where n and m are integers) for a unit cell that becomes a black cell. The circular dots are arranged in the cell by intermittently irradiating the laser beam while controlling the irradiation position of the laser beam.

In the dot marking method in the present embodiment, the unit cell size can be controlled. That is, if the code size is specified as a parameter, the control unit 30 can calculate the size of the unit cell and perform marking with the size of the unit cell.
Therefore, even if the amount of information stored in the two-dimensional code increases, it is not necessary to increase the code size, and it is possible to cope with it by decreasing the unit cell size.

Furthermore, in this embodiment, a dot diameter can be set as a marking parameter.
When a kind of dot diameter is set as a marking parameter, a two-dimensional code configured with the same dot diameter can be marked as shown in FIGS. 10 (a), 10 (b), and 10 (c). In this case, even if the dot marking place is the same, different information can be coded by changing the dot diameter, so the amount of information that can be expressed by the two-dimensional code can be increased.
Further, by using a small dot diameter, it becomes possible to incorporate more information into a two-dimensional code having the same code size.

Further, as shown in FIG. 10C, it is possible to mark a two-dimensional code by mixing dots having different dot diameters. In this case, a dot diameter is set for each dot coordinate, and marking is performed by converting the set dot diameter into wavelength information to produce marking information.
In this way, by marking two-dimensional code with a mixture of dots having different dot diameters, the amount of information that can be expressed by the two-dimensional code is dramatically increased.

An example of the marking state of characters in this embodiment is shown in FIG.
The computer 30 acquires the coordinates of the boundary line of the character from the bitmap data, acquires the coordinates for horizontal filling, and stores them. That is, the coordinates of the start point and end point are acquired from the top in the horizontal direction. Then, the number of dots, the dot diameter, and the dot coordinates are calculated so as to fully satisfy the area of the figure surrounded by a certain start point and end point and the next start point and end point.
In this way, by changing the dot diameter, it is possible to mark a character with less unevenness at the boundary portion.

In the present embodiment, it is possible to mark an image having a light and shade density such as a photographic image.
The photographic image is created based on the image taken from the scanner 10.
The photographic image is stored in the computer 30 in the form of a bitmap file as well as letters and numbers.
The marking of the photographic image is controlled as follows so that the image discrimination power similar to that of the photograph can be provided.

A photographic image is expressed as an aggregate of dots having different diameters.
In the conventional printing technique, gray scale is expressed by adjusting the density of halftone dots. That is, a portion where the density of halftone dots is high is dark, and a portion where the density of halftone dots is low is light.
In this embodiment, the dot by laser marking is used as a halftone dot, but it is possible to adjust the dot density by changing the dot diameter to express a gray scale.

That is, the color becomes darker by increasing the diameter of dots existing in the same area, and the color becomes lighter by decreasing the dot diameter.
The computer 30 acquires density data of the photographic image and performs gray replacement.
Further, the gray scale for each unit area is recognized, and the dot diameter and the dot coordinates corresponding to the gray scale for each unit area are calculated and set.
The dot diameter is converted into wavelength information to create marking data, and laser marking is performed according to the marking data.

In the dot marking method in the present embodiment, the influence on the object to be marked is less than that of so-called vector marking.
In laser marking, since a high-energy laser beam is irradiated onto the object to be marked, there is a high possibility that defects such as cracks and fracture marks will occur around the dots, and there are many problems in durability.
In the present embodiment, since the dot marking method is employed, there is a low possibility that defects such as cracks and fracture marks occur as will be described later.

FIG. 12 shows the generation direction of the radiation pressure when the laser beam is incident upon dot marking in this embodiment, and FIG. 13 shows the generation direction of the radiation pressure when the laser beam is emitted.
The object to be marked W absorbs part of the radiation when the radiation emitted from the laser is incident, and most of the other is emitted to the outside of the object to be marked W again.
The radiation pressure is a kind of mechanical pressure generated in the direction perpendicular to the traveling direction when the radiation is incident or emitted.
If the density of the radiation increases, the radiation pressure increases in proportion to it. Therefore, if the irradiation time and output of the laser light increase, the destruction phenomenon to the object to be marked W is activated.
As shown in FIG. 12, the radiation pressure when the laser beam is incident is generated radially outward from the center of the dot.
In addition, the radiation pressure at the time of laser light emission is generated radially outward from the center of the dot and also in a direction perpendicular to the radially generated radiation pressure.
At this time, the radiation pressure generated radially from the center of the dot is the pressure necessary for marking the dot, but the radiation pressure generated in the direction perpendicular to the radially generated radiation pressure depends on the marking method. Is a cause of forming fracture marks such as cracks.

FIG. 14 is an explanatory view conceptually showing the occurrence of cracks when glass is used as the object to be marked W. FIG.
As described above, when laser marking is performed on glass, cracks extending radially from the center and cracks extending radially from the center are generated on the inner wall surface of the dot.
In this embodiment, since the dot marking method is adopted as the laser marking method, the cracks that extend in the vertical direction with respect to the radially extended cracks are confined to the inner wall surface of the dots. Become.
Therefore, the possibility that cracks are generated in the periphery of the dot on the surface of the object to be marked W is reduced, and the durability of the product on which laser marking has been performed is improved.

FIG. 15 is an explanatory diagram comparing the occurrence of cracks between the marking by the dot marking method in the present embodiment and the marking by the vector marking method which is a conventional technique.
The vector marking method is a method of painting a figure or the like to be marked on the object to be marked W with a line.
When the vector marking method is adopted, it is difficult to contain the crack inside the figure that marks the crack, and as shown in FIG. 15 (b), a crack is generated outside the figure, particularly at the intersection where multiple lines overlap. Will occur.
Moreover, since the radiation pressure with respect to the laser radiation continuously overlaps the line, crack expansion is induced and the surface of the object to be marked W is greatly damaged.
In the dot marking method, as shown in FIG. 15A, it is possible to contain the crack inside the dot, so that the crack stays inside the dot and the possibility of extending to the outside is reduced.

Further, in the present embodiment, it is possible to change the mass of dots irradiated to the object to be marked W by changing the laser irradiation delay time of the marking parameter.
This laser irradiation delay time can be adjusted in the range of 1 to 100,000 μsec.
In this way, by adjusting the laser irradiation delay time, it is possible to change the dot mass and adjust the marking strength and radiation pressure on the object to be marked W.
Therefore, stable marking can be performed on the object to be marked W of various materials such as glass, metal, and resin having different material characteristics.

As described above, according to the present invention, the dot diameter can be adjusted by converting the wavelength of the laser beam by the wavelength selection device 48.
Furthermore, it is possible to finely adjust the dot diameter by switching to an appropriate condensing lens by the condensing lens selection device 59 and narrowing down the laser light having the converted wavelength.
As described above, according to the present invention, it is possible to perform marking on the object to be marked W while finely adjusting the dot diameter by the wavelength selection device 48 and the condenser lens selection device 59.
Therefore, the marking density occupying the unit area when marking can be adjusted, and the visual color density of the marking can be finely adjusted.

  In addition, since the dot marking method is employed in the present invention, it is possible to suppress the occurrence of fracture marks such as cracks as compared with the laser marking by the vector marking method, and to provide a highly durable marking product. It becomes possible.

  Furthermore, in the present invention, since it is possible to adjust the dot mass by changing the laser irradiation delay time, it is possible to mark various substances having different strengths and physical properties such as glass, metal, and resin. It becomes possible.

It is explanatory drawing which shows the whole structure of the laser marking apparatus which concerns on one Embodiment of this invention. It is explanatory drawing which shows the structure of the data control part which concerns on one Embodiment of this invention. It is explanatory drawing which shows the structure of the laser marker which concerns on one Embodiment of this invention. It is explanatory drawing which shows the structure of the wavelength selection apparatus which concerns on one Embodiment of this invention. It is explanatory drawing which shows the principle of the wavelength converter which concerns on one Embodiment of this invention. It is explanatory drawing which shows the structure of the condensing lens apparatus which concerns on one Embodiment of this invention. It is explanatory drawing which shows the flow of the process of the laser marking method which concerns on one Embodiment of this invention. It is explanatory drawing which shows the dot diameter change by the wavelength of the laser beam which concerns on one Embodiment of this invention. It is explanatory drawing which shows the mode of the difference in marking by the difference in the step size of the dot which concerns on one Embodiment of this invention. It is explanatory drawing which shows the variation of the two-dimensional code which concerns on one Embodiment of this invention. It is explanatory drawing which shows the marking state of the character which concerns on one Embodiment of this invention. It is explanatory drawing which shows the generation | occurrence | production direction of the radiation pressure when the laser beam which concerns on one Embodiment of this invention injects into a to-be-marked body. It is explanatory drawing which shows the generation direction of the radiation pressure at the time of the laser beam which concerns on one Embodiment of this invention being discharge | released from a to-be-marked body. It is explanatory drawing which shows the generation | occurrence | production state of the crack in the dot which concerns on one Embodiment of this invention. It is explanatory drawing which shows the crack generation state in the dot marking which concerns on one Embodiment of this invention, and the crack generation state in vector marking.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Scanner 20 Tablet 21 Input part 22 Pen 30 Computer 31 Display part 32 Keyboard 33 Mouse 36 Memory | storage part 36a ROM
36b RAM
37 Input / output unit 36c Hard disk 40 Laser marker 41 Controller 43 Q switch element 44 Internal shutter 45 External shutter 46 Attenuator 47 Galvano mirror 48 Wavelength selection device 48a to 48c Wavelength conversion device 48d Substrate 48e Rotating shaft 50 Laser oscillator 51 Total reflection mirror 52 Inside Aperture 53 Lamphouse 54 Output mirror 55 Aperture 56 Leveling mirror 57 Galileo expander 58 Aperture 59 Condensing lens selector 59a to 59c Condensing lens 59d Substrate 59e Laser beam passage position 61 First harmonic dot 62 Second harmonic dot 63 3rd harmonic dot 64 4th harmonic dot 480 Nonlinear crystal 481 Filter S Laser marking device W Marked object

Claims (11)

A wavelength selection device comprising: a laser oscillation device that emits spherical dot-shaped laser light; and a plurality of wavelength conversion devices that convert wavelengths of the laser light incident from the laser oscillation device to different wavelengths, and
A condensing lens for condensing the laser light on the marking material,
The wavelength selection device includes a wavelength conversion device switching unit, and the wavelength switching unit is formed so as to be able to select whether one of the plurality of wavelength switching devices is arranged at the incident position of the laser beam. A laser marking device characterized by comprising: Provided with a control means for creating marking information for marking the material to be marked,
2. The laser according to claim 1, wherein the wavelength conversion device to which the laser beam is incident is switched by drivingly controlling the wavelength conversion device switching means in accordance with irradiation laser wavelength information as marking information created by the control means. Marking device. The wavelength selection device is a device that switches the wavelength conversion device to convert the wavelength of the laser light into laser light of any one of the first to fourth harmonics,
2. The laser marking according to claim 1, wherein the dot diameter formed on the material to be marked is controlled in a range of 1 μm to 70 μm by converting the wavelength of the laser light with the wavelength selection device. apparatus. A laser oscillation device for emitting spherical dot-shaped laser light;
A condensing lens selection device comprising a plurality of condensing lenses for condensing the laser light incident from the laser oscillation device on the marking material;
The condensing lens selection device includes condensing lens switching means, and the condensing lens switching means selectively selects one of the plurality of condensing lenses at a position where the laser light is incident. A laser marking device characterized by being arranged. Provided with a control means for creating marking information for marking the material to be marked,
5. The condensing lens to which the laser light is incident is switched by drivingly controlling the condensing lens switching unit according to irradiation laser wavelength information as marking information created by the control unit. Laser marking device. A laser oscillation device for emitting spherical dot-shaped laser light;
A wavelength selection device comprising a plurality of wavelength conversion devices for converting the wavelengths of the laser light emitted from the laser oscillation device into different wavelengths, and
A condensing lens selection device comprising a plurality of condensing lenses for condensing the laser light whose wavelength has been converted by the wavelength selection device on a marking target material,
The wavelength selection device includes a wavelength conversion device switching unit, and the wavelength switching unit is formed so as to be able to select whether one of the plurality of wavelength switching devices is arranged at the incident position of the laser beam,
The condensing lens selection device includes condensing lens switching means, and the condensing lens switching means selectively selects one of the plurality of condensing lenses at a position where the laser light is incident. A laser marking device characterized by being arranged. Provided with a control means for creating marking information for marking the material to be marked,
According to the irradiation laser wavelength information as marking information created by the control means, the wavelength conversion device switching means is driven and controlled to switch the wavelength conversion device on which the laser light is incident, and the condensing lens switching means is driven and controlled. The laser marking device according to claim 6, wherein the condenser lens to which the laser beam is incident is switched. The wavelength selection device is a device that switches the wavelength conversion device and converts the wavelength of the laser light into laser light of any wavelength from the first harmonic to the fourth harmonic,
The condensing lens selection device is a device for switching the plurality of condensing lenses to narrow down the laser light, wherein the wavelength selection device converts the wavelength of the laser light, and further converts the wavelength of the laser light. The dot diameter formed on the marking target material is controlled in a range of 0.1 μm or more and 50 μm or less by narrowing down with the condensing lens selected by the condensing lens selection device. Item 7. The laser marking device according to Item 6. The control means includes time control means for controlling a laser irradiation delay time, and the dot mass irradiated to the object to be marked is changed by controlling the laser irradiation delay time by the time control means. The laser marking device according to claim 2, claim 5, or claim 7. The laser marking apparatus according to claim 9, wherein the laser irradiation delay time is controlled in a range of 1 to 100000 μsec. An image information acquisition process for capturing image information;
An information acquisition step of acquiring at least density information and coordinate information from the captured image information;
Based on the density information, a dot diameter information acquisition step for calculating dot diameter information indicating a dot diameter of a dot to be marked;
Based on the dot diameter information, a wavelength information acquisition step for setting wavelength information indicating the wavelength of the laser beam to be irradiated;
A condenser lens information setting step for setting condenser lens information indicating which one of the plurality of condenser lenses to use based on the wavelength information; and
Marking information setting step for setting marking information from the coordinate information, the wavelength information, and the condenser lens information,
In accordance with the wavelength information, a wavelength conversion device switching step of switching a wavelength conversion device by controlling a wavelength selection device that includes a plurality of wavelength conversion devices and converts the wavelength of the laser light;
A condenser lens switching step of switching a condenser lens by controlling a condenser lens selection device including a plurality of condenser lenses that collect the laser light on a marking target material according to the condenser lens information;
A laser marking step of irradiating a marking target material with a laser beam in accordance with the coordinate information.

Images