JP2005014089A - Laser marking method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for marking a plane figure projected on the surface of a workpiece having not only a flat surface but also a curved surface or projected on the inside of a transparent workpiece at high speed without deformation, by taking into consideration the shape of a plotting surface in the workpiece. <P>SOLUTION: In a laser marking method, a prescribed figure is plotted by scanning a laser beam emitted from a laser light source, while forming an image on a scanning surface through the control of a galvano-mirror and the control of operation of an image forming means based on the data of the figure. The method is characterized in that, on the basis of corrected data calculated from the shape of the workpiece, the galvano-mirror and the image forming means are controlled so that the plane figure is plotted as the figure projected on the surface or the inside of the workpiece. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention scans a laser beam using a galvanometer mirror and marks a pattern on the surface of a metal, glass, resin, or the like, or inside a transparent material such as glass or resin, that is, a laser for drawing a figure. The present invention relates to a laser marking method using a marking device. In particular, the present invention relates to a laser marking method using a laser marking apparatus that draws a figure on a workpiece using laser light condensed by a condenser lens that is an imaging means.

  The laser marking method is known from Patent Document 1, Patent Document 2, and the like.

  For example, Patent Document 1 discloses a laser marking device using a galvano mirror and a laser scanning position correction processing method. However, the correction processing method described in Patent Document 1 is a method for correcting pincushion distortion and barrel distortion generated by using a general galvanometer mirror, or the amount of pattern rotation, in other words, in a plane. This is a scanning position correction processing method. The marking position is different from the original marking position due to surface irregularities when the workpiece to be marked has a curved shape, or the influence of refraction when marking inside the transparent material. There is no disclosure of a method for correcting misalignment. Further, the correction processing method described in Patent Document 1 does not disclose a correction method for the deviation of the laser focusing position in the optical axis direction.

  In a laser marking apparatus using a galvanometer mirror according to the prior art, the laser beam is scanned radially from the center of the mirror, so that it is incident on the shape of the workpiece surface and the transparent material as in Patent Document 1, for example. If refraction and the like are not taken into consideration, there is a problem that the marked pattern is distorted reflecting the unevenness and refraction of the workpiece. Further, since the light condensing position is not corrected, there is a problem in that the surface unevenness is deviated from the laser beam processable region and a portion that is not marked is generated.

  Patent Document 2 discloses a method for correcting the condensing position of laser light in a laser marking apparatus that combines a stage that can move in two directions of X and Y directions orthogonal to the galvanometer mirror. However, the marking device described in Patent Document 2 is a method in which one galvanometer mirror fixed to a movable stage moves in the plane and scans the laser beam, and the correction amount of the condensing position is: This method is required for the amount of movement of the galvanometer mirror in the X direction and the amount of movement in the Y direction, and does not disclose a method for correcting the condensing position according to the shape of the surface of the workpiece.

In the correction method described in Patent Document 2, when the shape of the workpiece surface is not taken into consideration, the laser marking device of Patent Document 2 is a pattern that is marked to irradiate laser light from a predetermined direction on the workpiece surface. However, there is a problem in that the surface unevenness deviates from the laser beam processable region, and a portion that is not marked is generated. Furthermore, since the scanning of the laser beam is not performed by rotating the galvanometer mirror but by the parallel movement of the galvanometer mirror itself, it is difficult to increase the marking speed as much as the scanning method using the rotation of the galvanometer mirror. there were.
Japanese Patent Laid-Open No. 2002-321072 Japanese Unexamined Patent Publication No. 2000-202655

  In the conventional laser marking apparatus, when the above correction method is performed and a plane figure is drawn along the surface of the curved workpiece, the laser beam is scanned radially from the center of the X mirror. Due to the influence of the surface curvature of the workpiece, the coordinates of the points processed on the workpiece surface do not match the coordinates of the original graphic data. Since they do not match, there is a problem that the figure to be marked is not projected onto the surface of the workpiece and is distorted due to the influence of the surface curvature of the surface of the workpiece.

  Furthermore, when the surface curvature of the workpiece increases, there is a problem that a part that is not marked out of the laser beam processable region is generated.

  Furthermore, when a plane figure is to be drawn inside a transparent workpiece, when the laser beam is scanned radially from the center of the mirror, the laser beam is refracted when entering the transparent material. The angle of refraction increases as the drawing position moves away from the origin and the incident angle increases, and the locus of the laser beam condensing position does not become flat. Since the figure does not become a flat surface, the figure to be marked is not projected inside the workpiece, but has a problem that it is distorted according to the distance from the origin.

  In addition to the conventional control method described above, the present invention takes into account the shape of the drawing surface on the workpiece, so that not only a conventional plane but also a newly projected plane on the surface of the workpiece An object of the present invention is to provide a laser marking method for drawing a figure or a planar figure projected on the inside of a transparent workpiece at high speed without distortion.

  The laser marking method of the present invention is a conventional laser marking method in which a method for creating data for controlling a mirror and a condenser lens is analyzed, and the data is corrected by the laser marking method of the present invention. Thus, not only a plane but also a new curved surface can be drawn on the workpiece.

  The laser marking method of the present invention comprises a pair of galvanometers that scan laser light emitted from a light source means two-dimensionally in two orthogonal directions and an imaging means that forms an image on a target surface, and a planar figure to be drawn When drawing the point on the workpiece onto which the data is projected, the coordinates on the reference plane through which the laser beam passes are obtained, and using these coordinates, the swing angle and the focusing position of the X mirror and the Y mirror are corrected. Correction data is calculated.

  In the laser marking method of the present invention, for the control of the X mirror and Y mirror of the galvanometer, a signal corresponding to the calculated required swing angle is transmitted to the drive device for the X mirror and Y mirror, so that the imaging means For example, with respect to a condensing lens, the shift of the focal position is obtained, in other words, correction data is obtained, the correction data is converted into a signal, transmitted to the driving device, and the condensing lens is moved. .

  That is, the present invention scans a laser beam emitted from a laser light source while forming an image on a surface to be scanned by controlling operations of a galvano mirror and an image forming unit based on drawing data to be drawn. In the laser marking method for drawing, the operation of the galvanometer mirror and the imaging means for drawing a plane figure as a figure projected on the surface of the workpiece by correction data calculated from the shape of the drawing surface of the workpiece It is a laser marking method characterized by controlling.

  Further, according to the present invention, the correction data is calculated based on a value obtained by comparing a reference plane determined from an optical system and a shape of a surface to be scanned for drawing a figure. It is a marking method.

  Furthermore, the present invention controls the operation of the galvanometer mirror and the imaging means to draw a plane figure inside the transparent workpiece by using correction data calculated based on the refractive index of the workpiece. This is a characteristic laser marking method.

  By using the laser marking method of the present invention, in addition to the laser marking method in the conventional laser marking apparatus, that is, the control method, the shape of the drawing surface on the workpiece is taken into consideration, so that not only the flat surface as in the past. A plane figure newly projected on the surface of a curved workpiece or a plane figure projected inside a transparent workpiece can be drawn at high speed without distortion.

  With the laser marking method of the present invention, in a laser drawing apparatus that scans laser light using two orthogonal galvanometer mirrors and a condensing lens that can move along the optical axis, if only a flat surface is used as in the prior art. First, a newly projected figure of a plane figure on the surface of a curved workpiece or a transparent workpiece is drawn at high speed without distortion.

  First, a conventional laser marking method forming the basis of the present invention will be described.

  FIG. 6 is an explanatory diagram for explaining a locus of a laser focusing position in planar drawing using a conventional laser marking method in which only planar drawing is performed. FIG. 6 is a diagram for explaining the conventional laser marking method, and is an explanatory diagram for explaining that the locus of the laser condensing position when the condensing lens is not moved is a curved surface.

  As shown in FIG. 6, in a laser marker using two galvanometer mirrors and an automatic condenser lens for a plane, an X mirror 2 for scanning the laser light emitted from the laser light source 1 in the X direction and the Y direction A Y mirror 3 for scanning is arranged, and the laser beam is based on graphic data about the rotation axis of the X mirror 2 in the X direction and around the rotation axis of the Y mirror 3 in the Y direction. Scanning is performed to form a pattern on the reference plane 6. The locus of the laser condensing position when the beam is scanned has a center on the galvanometer mirror side regardless of the change in the optical path length from the X mirror 2 to the reference plane 6 due to the arrangement of the condensing lens 4 and the objective lens 5. Since the convex curved surface 7 has the center O of the reference plane 6 as a vertex, the laser condensing position is linked with the movement of the X mirror 2 and the Y mirror 3 based on the graphic data drawn using CAD data or the like. By adjusting the position of the condenser lens 4, the trajectory is controlled so as to change from the curved surface 7 to the reference plane 6. Based on the data of the optical system, the control device calculates the swing angle of the X mirror 2 and the Y mirror 3 for drawing a plane figure and the deviation of the condensing position, and further the condensing lens 4 from the deviation of the condensing position. And the X mirror 2, the Y mirror 3 and the condenser lens 4 are controlled. In drawing, the swing angle of the X mirror 2 and the Y mirror 3 and the amount of movement of the condenser lens 4 are sequentially calculated and drawn, and the swing angle and the condenser lens of the X mirror 2 and Y mirror 3 created in advance are drawn. In some cases, the movement amount of 4 is sequentially called and drawn.

  FIG. 7 is an explanatory diagram of a method for controlling the operation of the galvanometer mirror and the image forming means in a conventional laser marking apparatus capable of only plane drawing. FIG. 7 is an explanatory diagram for explaining the deviation of the mirror swing angle and the condensing position, that is, calculation of correction data in the conventional laser marking method.

  Next, a general calculation method of correction data relating to the swing angle of the galvanometer mirror for drawing a plane figure will be described. The case where the surface of the workpiece is the reference plane 6, the laser beam is incident perpendicularly to the reference plane 6, and the condensing position thereof coincides with the center O of the reference plane 6, X mirror 2, Y mirror 3 The reference position of the condenser lens 4 is considered. A coordinate system for displaying graphic data is an orthogonal coordinate system (X, Y, Z) with the center O of the reference plane 6 as the origin. However, since all the Z coordinates of the points on the reference plane 6 are 0, they may be omitted here. If the centers of the X mirror 2 and the Y mirror 3 are A and B, respectively, the center distance between the X mirror 2 and the Y mirror 3 is AB, and the center distance between the Y mirror 3 and the reference plane 6 is BO. If the deflection angles of the laser beam due to the rotation of the X mirror 2 and the Y mirror 3 are θx and θy, respectively, the deflection of the laser beam due to the rotation of the X mirror 2 and the Y mirror 3 for drawing the point P on the reference plane 6. The angle is expressed by the following formula 1 and formula 2. As correction data, the swing angle of the X mirror 2 is θx, and the swing angle of the Y mirror is θy.

  Further, the displacement of the condensing position of the laser to be corrected by moving the condenser lens 4 from the point P ′ on the curved surface 7 to the point P on the reference plane 6 in order to draw a plane figure, PP ′ is a number. Equation 3 is obtained.

  Next, a marking method using the laser marking device of the present invention will be described.

  An apparatus for drawing a plane figure projected on a work surface by the marking method of the present invention is a collection mounted on a linear translator (not shown) in which the laser light emitted from the laser oscillator 1 can move along the optical axis. It is configured to pass through the optical lens 4 and the objective lens 5, pass through the X mirror 2 and the Y mirror 3 for scanning, and be condensed on the processing surface to be processed. The correction data as the swing angle and condensing position of the X mirror 2 and the Y mirror 3 necessary for drawing the figure is the coordinates of the given plane figure, in other words, the optical data of the drawing apparatus for the figure data to be drawn. It is calculated based on the system and the shape of the surface to be processed on which the plane figure is projected.

  Next, in addition to the calculation method described above, a plane figure projected onto the surface of the curved workpiece by taking into account the shape of the drawing surface of the workpiece, or a plane figure projected inside the transparent workpiece In the laser marking method of the present invention for marking an image at a high speed without distortion, the deflection of the X mirror and the Y mirror with respect to the graphic data to be drawn when drawing a figure obtained by projecting a plane figure onto the surface of a curved workpiece A method of calculating the deviation between the corner and the light converging position, that is, the correction data will be described.

  FIG. 1 is a diagram for explaining a calculation method of a swing angle of a galvanometer mirror and a moving amount of a condensing lens when drawing a plane figure projected on the surface of a curved workpiece. It is the front view seen along the Y direction of the taken orthogonal coordinate system.

  FIG. 2 is a diagram for explaining a method of calculating correction data as a swing angle of a galvanometer mirror and a moving amount of a condensing lens when drawing a plane figure projected on a curved workpiece surface. It is the side view seen along the X direction of the system.

  If the coordinate of the plane graphic data to be drawn is (x, y) and the distance from the reference plane 6 of the point Q on the workpiece whose position is projected in the Z direction is z, the machining surface that is the graphic data drawing point The point on 8 is Q (x, y, z), and the point where the laser beam for drawing the point Q intersects the reference plane 6 is P (X, Y, 0). When the X and Y coordinates of the point P are displayed using the coordinates of the point Q on the workpiece, they are expressed by the following equations (4) and (5). Note that a is a distance between the centers of the X mirror 2 and the Y mirror 3, and is a distance corresponding to AB in a conventional marking apparatus for drawing on a plane. b is a distance between the centers of the Y mirror 3 and the reference plane 6 and is a distance corresponding to BO in a conventional marking device for drawing on a plane.

  By using these coordinates, the deflection angles θx and θy of the laser beam by the X mirror 2 and the Y mirror 3 for drawing the point Q on the workpiece can be obtained in the case of a laser marking apparatus capable of performing only conventional plane drawing. It is considered in the same way, and is expressed by the formulas 6 and 7.

  Further, the deviation QP ′ of the condensing position of the laser beam can be considered in the same manner, and is obtained by the equation (8).

  The swing angle of the X mirror 2 and the Y mirror 3 necessary for drawing a figure is ½ of the laser beam swing angles θx and θy, and the amount of movement of the condensing lens corresponds to the shift of the condensing position. The amount of displacement of the condenser lens is processed by the control device.

  Next, a method for calculating correction data as a deviation of the swing angle and the condensing position of the X mirror and the Y mirror with respect to the graphic data in the case of drawing a planar graphic in the transparent workpiece in the laser marking method of the present invention. Show.

  FIG. 3 is a diagram for explaining a calculation method of the swing angle of the galvanometer mirror and the amount of movement of the condenser lens when drawing a plane figure inside the transparent workpiece, and is taken at the center of the reference plane. It is the front view seen along the Y direction of a rectangular coordinate system.

  FIG. 4 is a diagram for explaining a calculation method of the swing angle of the galvanometer mirror and the amount of movement of the condenser lens when drawing a plane figure inside the transparent workpiece, and is taken at the center of the reference plane. It is the front view seen along the X direction of a rectangular coordinate system.

  As shown in FIGS. 3 and 4, the transparent plate is arranged so that the surface thereof coincides with the reference plane 6.

  When the coordinates of a certain plane graphic data are (x, y) and the position is projected on the plane 9 located at a depth z in the Z direction from the surface of the workpiece, the point on the plane 9 is Q (x, y, z). When the laser beam for processing the point Q is refracted at the point P (X, Y, 0) on the reference plane 6 which is the surface of the transparent workpiece and passes through the point Q, the optical path of the laser beam is processed. In order to follow Snell's law upon incidence on the object, the refractive index of the transparent workpiece is n.

  FIG. 5 is an explanatory diagram for explaining the relationship between the coordinates of the points inside the transparent workpiece and the coordinates of the points on the reference plane 6.

  As shown in FIG. 5, the relationship represented by Equation 9 is established.

Further, when the formula 9 is displayed using the coordinates of the point P on the reference plane 6 and the point Q on the plane 9 on which the figure is projected, the relationship represented by the formula 10 is established.

  Further, on the laser light incident surface, the relationship represented by the equation (11) is established for the coordinates of the point P on the reference plane 6 and the point Q on the plane 9 on which the figure is projected.

  Accordingly, the coordinates X and Y of the point P on the reference plane 6 satisfying the equations 10 and 11 are obtained, and the point Q on the projection plane inside the transparent workpiece is drawn by using these coordinates. Therefore, the deflection angles θx and θy of the laser beam by the X mirror 2 and the Y mirror 3 can be considered in the same manner as in the case of a conventional laser marking apparatus capable of only plane drawing, and are obtained by the equations of Equations 6 and 7.

  The correction amount QP ′ of the laser beam condensing position is the same as that of the prior art except that the condensing position is increased by the refractive index n in the transparent workpiece compared to the air. Since it can be considered in the same manner as in the case of a laser marking apparatus that can perform only planar drawing, it is calculated by the formula (12).

  The swing angle of the X mirror 2 and the Y mirror 3 necessary for drawing a figure is ½ of the laser beam swing angles θx and θy, and the amount of movement of the condensing lens corresponds to the shift of the condensing position. The amount of movement of the condenser lens is processed by the control device.

  Further, when drawing a plane figure inside the workpiece having a flat projection surface, the drawing is performed by controlling the operation of the galvanometer mirror and the imaging means based on the correction data calculated based on the refractive index. When drawing a planar figure projected inside the workpiece, it is calculated by adding the refractive index of the workpiece to the correction data calculated from the shape of the projection surface of the workpiece relative to the figure data to be drawn. It is preferable to perform drawing by controlling the operation of the galvanometer mirror and the image forming means based on the correction data, that is, the deviation of the swing angle and condensing position of the X mirror and Y mirror.

Example 1
Using a laser marking device consisting of a UV pulse laser, a galvanometer mirror that combines two mirrors, an X mirror and a Y mirror, and imaging means, curved glass is projected into a shape based on the graphic data drawn by CAD processing. Draw on the surface. The UV pulse laser drawing conditions were a pulse energy of 90 μJ, a repetition frequency of 25 kHz, and a scanning speed of 65 mm / s. The curved glass was a part of a spherical surface having a radius of 2000 mm, and a figure was drawn on the surface in a range of 200 × 200 mm. The layout of the optical system was such that the distance between the center of the X mirror and the Y mirror was 30 mm, and the distance from the center of the Y mirror to the apex of the spherical glass was 270 mm. As a condensing lens for condensing laser light, a plano-convex lens having a condensing distance of 500 mm is used, and this lens is attached to a linear translator that can move along the optical axis in order to adjust the condensing position. .

    The difference between the reference plane in the x direction, −100 mm to 100 mm, the y direction, and −100 mm to 100 mm and the z direction of the glass shape is the value shown in Table 1. The deviations of the X coordinate, Y coordinate, and condensing position were calculated as shown in Table 2, Table 3, and Table 4, respectively. Table 1 shows the difference (mm) between the reference plane and the curved surface in the z direction. Table 2 shows X coordinates corrected based on the coordinates (x, y) of the graphic data to be drawn. Table 3 shows the Y coordinate corrected based on the coordinates (x, y), and was corrected by the above equation (5). Table 4 shows the condensing position corrected based on the coordinates (x, y), and was corrected by the above-described equation (8).

    The coordinates (x, y) of the figure to be drawn sent from the CAD are compared with the deviations of the X coordinate, the Y coordinate, and the condensing position in Tables 2 to 4 calculated in advance using the equations (4) and (5). With respect to the data between the indicated coordinates, while performing linear interpolation, the X mirror swing angle to be the X coordinate shown in Table 2, the Y mirror swing angle to be the Y coordinate shown in Table 3, and Table 4 The amount of movement of the condensing lens was controlled so that the converging position shown in FIG. That is, the control of the swing angle of the X mirror and Y mirror for drawing graphic data consisting of the coordinate group of (x, y) does not use the x and y data sent from the CAD as it is, and coordinates (x, y By substituting the corrected coordinates (X, Y) calculated from y) into the equations (6) and (7) and calculating and controlling the deflection angles θx and θy of the laser beam, a plane figure is projected onto the spherical glass without distortion. It was drawn as a figure.

Example 2
As in Example 1, using a laser marking device comprising a UV pulse laser, a galvano mirror that combines two mirrors, an X mirror and a Y mirror, and an imaging means, a figure based on data to be drawn processed by CAD is used. Draw inside the flat glass. A flat glass with a thickness of 15 mm and a size of 100 × 100 mm was drawn, and a plane figure was drawn at a position 5 mm from the surface. The UV pulse laser irradiation conditions and the optical system layout were the same as in Example 1.

    The refractive index of the glass was used as 1.52, and the deviation of the X coordinate, the y coordinate, and the condensing position was calculated as shown in Table 5, Table 6, and Table 7, respectively, in the irradiation range. Table 5 shows X coordinates corrected based on coordinates (x, y) as graphic data to be drawn, and Table 6 shows Y coordinates corrected based on coordinates (x, y). The coordinates were obtained as values satisfying the above equations (10) and (11) at the same time. Table 7 shows the deviation of the condensing position corrected based on the coordinates (x, y), and was corrected by the above equation (12).

    The coordinates (x, y) as graphic data to be drawn sent from the CAD are compared with the deviations of the X, Y, and condensing positions calculated in advance in Tables 5 to 7, and the coordinates shown in the table are compared. The data is collected by linear interpolation, with the X mirror swing angle as shown in Table 5, the Y mirror swing angle as shown in Table 6, and the converging position deviation in Table 7. The position of the optical lens was controlled. That is, the control amount for drawing the graphic data composed of the coordinate group of (x, y) does not use the x and y data sent from the CAD as it is, and the X coordinate calculated from the coordinates (x, y), By substituting the Y coordinate into the equations (6) and (7) and calculating and controlling the deflection angles θx and θy of the laser beam, a figure projected without distortion on the inside of the flat glass was drawn.

It is a figure for demonstrating the calculation method of the swing angle of a galvanometer mirror and the movement amount of a condensing lens at the time of drawing the plane figure projected on the curved surface of the workpiece, and is the orthogonal coordinate system taken at the center of the reference plane It is the front view seen along the Y direction. It is a figure for demonstrating the calculation method of the swing angle of a galvanometer mirror and the movement amount of a condensing lens at the time of drawing the plane figure projected on the curved surface of a workpiece, and it looked along the X direction of the same coordinate system It is a side view. It is a figure for demonstrating the calculation method of the swing angle of a galvanometer mirror at the time of drawing a plane figure inside a transparent work piece, and the amount of movement of a condensing lens, and is an orthogonal coordinate system taken at the center of a reference plane. It is the front view seen along the Y direction. It is a figure for demonstrating the calculation method of the swing angle of a galvanometer mirror at the time of drawing a plane figure inside a transparent work piece, and the amount of movement of a condensing lens, and is an orthogonal coordinate system taken at the center of a reference plane. It is the front view seen along the X direction. It is a figure for demonstrating the relationship between the coordinate of the point in the inside of a transparent workpiece, and the coordinate of the point on a reference plane. It is a figure for demonstrating the locus | trajectory of a laser beam condensing position. It is explanatory drawing of the control method of the operation | movement of the galvanometer mirror and the image formation means in the laser marking apparatus which can perform only conventional plane drawing.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Laser oscillator 2 X mirror 3 Y mirror 4 Condensing lens 5 Objective lens 6 Reference plane 7 The locus | trajectory of the laser condensing position when a condensing lens is fixed to the origin 8 The surface 9 of a curved workpiece 9 Transparent workpiece A plane located at a certain depth of an object

Claims (3)

A laser marking method for drawing a predetermined figure by scanning a laser beam emitted from a laser light source while forming an image on a surface to be scanned by controlling operations of a galvanometer mirror and an imaging means based on drawing data to be drawn The operation of the galvanometer mirror and the imaging means is controlled in order to draw a plane figure as a figure projected on the surface of the work piece by correction data calculated from the shape of the drawing surface of the work piece Laser marking method. 2. The correction data according to claim 1, wherein the correction data is calculated based on a value obtained by comparing a reference plane determined by the optical system and a shape of a surface to be scanned for drawing a figure. Laser marking method. A laser marking method, comprising: controlling operations of a galvanometer mirror and an imaging means to draw a plane figure inside a transparent workpiece by correction data calculated from a refractive index of the workpiece.

Images