JP7633014B2 - Distortion correction processing device, distortion correction method, and program - Google Patents

Description

The present invention relates to a distortion correction processing device, a distortion correction method, and a program.

In inkjet devices that print on an object by ejecting ink from an inkjet head, laser processing devices that drill holes in an object by irradiating a laser beam onto the object, and laser annealing devices that irradiate a laser beam onto a semiconductor substrate (object) to anneal it, alignment marks on the object are detected to position the object. At this time, the position of the alignment mark is detected by performing image processing on the image showing the alignment mark.

In order to detect the position of the alignment mark with high accuracy, it is preferable to correct the distortion of the lens (for example, see Patent Document 1 below). In the distortion correction method disclosed in Patent Document 1, a five-dimensional polynomial correction equation is set as a function that converts the distance from the origin of the image plane to the distorted image (image height) to the distance before distortion. This polynomial equation is used to correct the distance after distortion to the distance before distortion.

JP 2001-133223 A

When the optical axis of the imaging device is tilted relative to the surface of the object to be measured, the amount of distortion to be corrected changes depending on the circumferential position around the origin of the image plane. However, in the correction method disclosed in Patent Document 1, distortion is corrected only based on the distance from the origin of the image plane, so distortion cannot be corrected with high precision when the optical axis of the imaging device is tilted.

The object of the present invention is to provide a distortion correction processing device, a distortion correction method, and a program that can perform distortion correction with high accuracy even when the optical axis of the imaging device is oblique to the surface of the object to be measured.

According to one aspect of the present invention,
a storage unit in which, when an xy Cartesian coordinate system is defined on an image plane of an imaging device, distortion correction information is stored which indicates, for each of a plurality of sections divided by a plurality of boundaries extending radially from a reference point on the image plane, an x-coordinate correction factor for correcting an x-coordinate on the image plane, a y-coordinate correction factor for correcting a y -coordinate on the image plane, and a relationship with a distance from the reference point;
There is provided a distortion aberration correction processing device that includes a processing unit that selects at least one section from the plurality of sections based on the coordinates of the correction target section within the image plane, determines an x-coordinate correction rate and a y-coordinate correction rate based on the distortion aberration correction information for the selected section and the distance from the reference point to the correction target section, and corrects the coordinates of the correction target section based on the determined x-coordinate correction rate and y-coordinate correction rate .

According to another aspect of the invention,
an image of a measurement object is captured using an image capture device for which distortion aberration correction information indicating a relationship between an x- coordinate correction factor for correcting an x-coordinate in an image and a y-coordinate correction factor for correcting a y-coordinate in an image, and a distance from a reference point, for each of a plurality of sections divided by a plurality of boundaries extending radially from a reference point in the image plane of the image capture device, is known when an x-y orthogonal coordinate system is defined on an image plane of the image capture device;
determining a correction target location for correcting coordinates within the image plane;
selecting at least one section from the plurality of sections based on a position of the correction target portion within the image plane;
determining an x-coordinate correction rate and a y-coordinate correction rate based on the distortion aberration correction information for the selected section and the distance from the reference point to the correction target location;
A distortion correction method is provided in which the coordinates of the correction target portion are corrected based on the determined x-coordinate correction rate and y-coordinate correction rate .

According to yet another aspect of the present invention,
a step of acquiring an image of a measurement object captured using an imaging device for which distortion aberration correction information indicating a relationship between an x- coordinate correction factor for correcting an x-coordinate in an image and a y-coordinate correction factor for correcting a y-coordinate in an image, and a distance from a reference point, for each of a plurality of sections divided by a plurality of boundaries extending radially from a reference point in an image plane of an imaging device, when an x-y Cartesian coordinate system is defined on an image plane of the imaging device, is known;
A step of determining a correction target portion to be corrected from an image captured by the imaging device;
selecting at least one section from the plurality of sections based on coordinates of the correction target area in the image plane;
determining an x-coordinate correction rate and a y-coordinate correction rate based on the distortion aberration correction information for the selected section and a distance from the reference point to the correction target location;
and a procedure for correcting the coordinates of the correction target portion based on the determined x-coordinate correction rate and y-coordinate correction rate .

By dividing the image plane into multiple sections and correcting distortion using distortion correction information set for each section, it is possible to perform distortion correction with high precision even when the optical axis of the imaging device is tilted relative to the surface of the object being measured.

FIG. 1 is a block diagram of a distortion correction processing device according to an embodiment. FIG. 2 is a diagram showing the contents of the distortion aberration correction information. FIG. 3 is a graph for explaining a method of correcting the coordinates of the correction target portion in the image plane. FIG. 4 is a flowchart showing a procedure for correcting the coordinates of the correction target area in the image plane. FIG. 5A is a diagram showing the distribution of images of multiple marks arranged in a matrix, captured using a telecentric lens, and FIG. 5B is a diagram showing the corrected coordinates of the marks calculated from the coordinates of the mark images using the method of this embodiment. 6A and 6B are diagrams showing images of a mark in the image plane when it is assumed that there is no distortion and when it is assumed that there is distortion when the optical axis of the imaging device is perpendicular to the surface of the object to be measured, and FIG. 6C is a graph plotting the relationship between the coordinate correction factor _Dx in the x-direction for the diagonal direction of the image plane and the distance r from the center point of the image plane. 7A and 7B are diagrams showing images of a mark in the image plane when it is assumed that there is no distortion and when it is assumed that there is distortion, respectively, when the optical axis of the imaging device can be inclined with respect to the surface of the object to be measured. FIG. 7C is a graph plotting the relationship between the coordinate correction factor D _x in the x direction for the diagonal directions of the image plane and the distance r from the center point of the image plane, without distinguishing between the four diagonal directions of the image plane. FIG. 7D is a graph plotting the relationship between the coordinate correction factor D _x in the x direction for the diagonal directions of the image plane and the distance r from the center point of the image plane, distinguishing between each of the sections Q1 to Q4. FIG. 8A is a schematic front view of an inkjet drawing device according to another embodiment, and FIG. 8B is a diagram showing the positional relationship in a plan view of a movable table, an ink ejection unit, and an imaging device. FIG. 9 is a flow chart showing a procedure for performing drawing using the inkjet drawing device.

A distortion correction processing device according to one embodiment will be described with reference to FIGS.
1 is a block diagram of a distortion aberration correction processing device 10 according to an embodiment. The distortion aberration correction processing device 10 according to this embodiment includes an input/output interface unit 11, a processing unit 12, and a storage unit 13. The processing unit 12 is, for example, a computer. The storage unit 13 stores a program 14 executed by the computer. The storage unit 13 further stores distortion aberration correction information 15. The contents of the distortion aberration correction information 15 will be described later with reference to FIG. 2. The storage unit 13 is, for example, an auxiliary storage device such as a hard disk drive (HDD) or a solid state drive (SSD).

The processing unit 12 acquires image data from the imaging device 40 via the input/output interface unit 11. The processing unit 12 performs image analysis to detect the coordinates of the image of the alignment mark in the image. The coordinates of this image are affected by lens distortion aberration and deviate from the actual coordinates indicating the actual position of the alignment mark. The processing unit 12 corrects the coordinates of the image using distortion aberration correction information 15 stored in the memory unit 13 to reduce the error with the actual coordinates of the alignment mark. The corrected coordinates are then passed to the control device 50 via the input/output interface unit 11. The control device 50 performs various processes based on the corrected coordinates of the alignment mark. The processing unit 12 and the control device 50 may be realized by a common computer. In this case, the processing unit 12 passes the corrected coordinates of the alignment mark to the control device 50 without going through the input/output interface unit 11.

Figure 2 is a diagram showing the contents of the distortion aberration correction information 15. An xy Cartesian coordinate system with a reference point O as the origin is defined on the image plane 41 of the imaging device 40 (Figure 1). Object points within the field of view of the imaging device 40 are transferred to the image plane 41. The image plane 41 is, for example, a square or rectangle, and the reference point O is the center of the square or rectangle. The x-axis and y-axis are defined to be parallel to one of the sides of the image plane 41.

The image surface 41 is divided into a number of sections Q1 to Q4 by a number of boundary lines BL extending radially from a reference point O. In this embodiment, the line segments connecting the reference point O and the midpoints of each side of the image surface 41 are used as the boundary lines BL. The four boundary lines BL correspond to the positive and negative parts of the x-axis and the positive and negative parts of the y-axis, and the sections Q1 to Q4 correspond to the first to fourth quadrants of the xy coordinate system, respectively.

Due to the influence of lens distortion aberration, etc., the position of image point _P1 corresponding to a certain observation point shifts from the position of image point _P0 when it is assumed that the lens has no aberration. Distortion aberration correction information 15 is information for correcting the coordinates of image point _P1 to obtain the coordinates of image point _P0 when there is no aberration, and includes a coordinate correction rate _Dx in the x direction and a coordinate correction rate _Dy in the y direction.

Next, a method for obtaining the distortion aberration correction information 15 for section Q1 will be described. An object to be observed, on which multiple marks with known positions are formed, is imaged by the imaging device 40 (Fig. 1) to obtain an image. The multiple marks are, for example, lattice points of a lattice pattern. The object to be observed is moved until the image of the mark serving as the reference point of the object to be observed coincides with reference point O on the image plane 41. For example, the image of the mark is analyzed to detect the position of the image of the mark, and the object to be observed is moved based on the detection result, thereby making it possible to match the image of the mark serving as the reference point with reference point O on the image plane 41. This procedure may be repeated multiple times to increase the accuracy of the match between the two.

By analyzing the obtained image, multiple image points located on the diagonal line of section Q1 with reference point O at one end are extracted from the image points of the multiple marks. One of the extracted multiple image points is denoted as _P1 . The image point without aberration corresponding to image point _P1 is denoted as _P0 . The coordinates of image point P1 are obtained by performing image analysis. The coordinates of image point _P0 without aberration corresponding to image point _P1 are denoted as ( _x0 , _y0 ), and the coordinates of image point _P1 are denoted as ( _x1 , _y1 ). _The coordinate correction rate _Dx in the x direction and the coordinate correction rate _Dy in the y direction are defined by the following equations.

The coordinate correction rate D _x in the x direction is the ratio of the amount of displacement x 1 -x ₀ in the x direction from the image point P ₀ when there is no aberration to the actual image point P ₁ to the length x ₀ in the x direction from the reference point O to the image point P ₀ when there is no aberration. The coordinate correction rate Dy in the y direction is the ratio of the amount of displacement y _{1 -y 0} in the y direction from the image point P ₀ when there is no aberration to the length y ₀ in the y direction from the reference point _O to the image point P ₀ when there is no aberration. Generally, the distortion aberration of a lens is small at the center of the image surface and large at the periphery. For this reason, the coordinate correction rates D _x and D _y depend on the distance r from the reference point O.

Measurement results for a plurality of image points _P1 on a diagonal line are plotted on a graph with the horizontal axis representing the distance r from the reference point O _to the actual image point P1 and the vertical axis representing the coordinate correction rate _Dx in the x direction. An approximation curve that approximates the distribution of the plurality of plotted points is determined. As a result, as shown in FIG. 2, the coordinate correction rate _Dx in the x direction for the section Q1 is defined as a function of the distance r. Similarly, the coordinate correction rate _Dy in the y direction is also defined as a function of the distance r. As a result, the distortion aberration correction information 15 for the section Q1 is obtained. In the graph of the distortion aberration correction information 15 for the section Q1 shown in FIG. 2, an example of the coordinate correction rate _Dx in the x direction and the coordinate correction rate _Dy in the y direction are respectively indicated by a thick solid line and a thin solid line.

In a similar manner, distortion correction information 15 can be obtained for the other sections Q2 to Q4. The obtained distortion correction information 15 is stored in the storage unit 13 (FIG. 1). If the distortion does not depend on the radial direction centered on the reference point O, the coordinate correction factors D _x and D _y will be approximately the same among the sections Q1 to Q4. However, in reality, the coordinate correction factors D _x and D _y vary among the sections Q1 to Q4 due to various factors. One factor that may cause the variation is, for example, the inclination of the optical axis of the imaging device 40 with respect to the surface of the observed object.

Next, a method of correcting the coordinates of a certain location in the image plane 41 (hereinafter referred to as a correction target location) to the coordinates when no aberration occurs will be described with reference to FIGS.
Fig. 3 is a graph for explaining a method of correcting the coordinates of the correction target portion Pt on the image plane 41. Fig. 4 is a flowchart showing a procedure for correcting the coordinates of the correction target portion Pt on the image plane 41.

First, the correction target location Pt in the image plane 41 is determined. The correction target location Pt corresponds to, for example, the center point of the image of the alignment mark. Based on the position of the correction target location Pt, two sections are selected from the four sections Q1 to Q4 (step S1). For example, of the boundary lines BL that separate the four sections Q1 to Q4, two sections on either side of the boundary line BL that forms the smallest angle with the direction from the reference point O toward the correction target location Pt are selected. In FIG. 3, the positive part of the y-axis corresponds to the boundary line BL that satisfies this condition. The two sections Q1 and Q2 on either side of the positive part of the y-axis are selected.

Next, based on the distortion aberration correction information 15 (FIGS. 1 and 2) for the two selected sections Q1 and Q2, the coordinate correction rates _Dx and Dy of the sections Q1 and Q2 corresponding to the distance r from the reference point O to the correction target point _Pt are weighted-averaged to obtain the coordinate correction rates _Dxt (r) and _Dyt (r) at the position of the correction target point Pt (step S2). For example, the weighted average is calculated based on the angle between the direction from the reference point O toward the geometric center of the two selected sections Q1 and Q2 (corresponding to the diagonal direction of the sections Q1 and Q2) and the direction from the reference point O toward the correction target point Pt.

ここで、Ｄ_ｘ１（ｒ）、Ｄ_ｙ１（ｒ）は、それぞれ区画Ｑ１について求められたｘ方向及びｙ方向の座標補正率であり、Ｄ_ｘ２（ｒ）、Ｄ_ｙ２（ｒ）は、それぞれ区画Ｑ２について求められたｘ方向及びｙ方向の座標補正率である。 When the angles between the direction from the reference point O toward the geometric centers of the two selected sections Q1 and Q2 and the direction from the reference point O toward the correction target location Pt are denoted as _θ1 and _θ2 , respectively, the coordinate correction rates _Dxt (r) and _Dyt (r) at the correction target location Pt are expressed by the following equations.

Here, D _x1 (r) and D _y1 (r) are the coordinate correction rates in the x and y directions, respectively, obtained for section Q1, and D _x2 (r) and D _y2 (r) are the coordinate correction rates in the x and y directions, respectively, obtained for section Q2.

Next, the coordinates of the correction target point Pt in the image plane are corrected based on the weighted average coordinate correction rates D _xt and D _yt in the correction target point Pt (step S3). For example, when the coordinates of the correction target point Pt are expressed as (x ₁ , y ₁ ) and the corrected coordinates are expressed as (x ₀ , y ₀ ), the corrected coordinates are calculated using the following formula:

Next, the excellent effects of this embodiment will be described with reference to FIGS. 5A and 5B.
Fig. 5A is a diagram showing the distribution of images of a plurality of marks arranged in a matrix, captured using a telecentric lens. Note that Fig. 5A shows the amount of deviation between the image of the marks when there is no aberration and the actual image, enlarged by 100 times. Fig. 5A shows that barrel distortion occurs.

Figure 5B shows the coordinates of the corrected mark image calculated from the coordinates of the actual mark image using the method of this embodiment. Figure 5B also shows the deviation from the mark image without aberration to the image after coordinate correction, enlarged 100 times. As shown in Figure 5B, it can be seen that the distortion aberration is corrected and a distribution close to the original matrix arrangement is obtained.

In this way, by using the method according to the above embodiment, the lens distortion aberration can be corrected and the coordinates of the mark image can be brought closer to the coordinates without aberration.

Next, with reference to Figures 6A to 6C and Figures 7A to 7D, we will explain why distortion aberration can be corrected with high precision even when the optical axis of the imaging device 40 (Figure 1) is tilted with respect to the surface of the object to be measured.

Figures 6A and 6B are diagrams showing the image of the mark in the image plane 41 when it is assumed that there is no distortion and when there is distortion, respectively, when the optical axis of the imaging device 40 is perpendicular to the surface of the object to be measured. The horizontal and vertical axes of Figures 6A and 6B represent the position in the x and y directions, respectively. Multiple marks are placed at the lattice points of the lattice pattern. In Figures 6A and 6B, the image of the mark is indicated by a filled-in circle symbol.

If it is assumed that there is no distortion, the positions of the images of the multiple marks coincide with the lattice points of a square lattice, as shown in Figure 6A. If it is assumed that there is distortion, the positions of the images of the marks deviate from the lattice points, as shown in Figure 6B. In Figure 6B, it is assumed that barrel distortion, which is significantly larger than the distortion of a typical lens, occurs.

6C is a graph plotting the relationship between the x-direction coordinate correction factor _Dx for the diagonal directions of the image plane and the distance r from the center point of the image plane without distinguishing between the four diagonal directions. Since distortion has low dependency on the direction of rotation about the center point of the image plane, the multiple measurement points plotted in the four diagonal directions can be accurately approximated by a single approximation curve.

Figures 7A and 7B are diagrams showing the image of a mark in the image plane 41 when it is assumed that there is no distortion and when there is distortion, respectively, when the optical axis of the imaging device 40 is tilted with respect to the surface of the object to be measured. The horizontal and vertical axes of Figures 7A and 7B represent positions in the x and y directions, respectively. Multiple marks are placed at the lattice points of the lattice pattern. In Figures 7A and 7B, the image of the mark is indicated by a filled-in circle symbol.

Because the optical axis of the imaging device 40 is tilted, as shown in FIG. 7A, the position of the mark image is shifted from the lattice point even if it is assumed that there is no distortion. Because there is no distortion, the image of a straight line on the measurement object will also be a straight line within the image plane. For example, if the perimeter of an area in which multiple marks are distributed is a square, the perimeter of the area in which the mark images are distributed within the image plane 41 will be a trapezoid.

If we assume that the same distortion aberration as that shown in Figure 6B occurs in the distribution of the mark images shown in Figure 7A, the area in which the mark images are distributed when it is assumed that there is distortion will have a shape that resembles a combination of a trapezoid and a barrel shape, as shown in Figure 7B.

Fig. 7C is a graph plotting the relationship between the coordinate correction factor _Dx in the x direction for the diagonal directions of the image plane 41 and the distance r from the center point of the image plane 41, without distinguishing between the four diagonal directions of the image plane 41. Since the magnitude and direction of the distortion aberration differ between the diagonal directions, the plotted measurement points are distributed over a wider range in the vertical axis direction than in the case shown in Fig. 6C. Even if one approximation curve is set for this distribution, there is a large error between the coordinate correction factor calculated from the approximation curve and the coordinate correction factor at each measurement point.

7D is a graph plotting the relationship between the coordinate correction factor _Dx in the x direction in the diagonal direction of the image plane 41 and the distance r from the center point of the image plane, with each of the sections Q1 to Q4 being distinguished from the others. The square symbols, triangle symbols, and circle symbols in the graph are plotted for the measurement points located on the diagonal lines of the sections Q2, Q3, and Q4, respectively. Note that for the section Q1 as well, the coordinate correction factor is calculated for a plurality of measurement points, but the measurement points are not shown in FIG. 7D.

The thin dashed line, thin solid line, thick dashed line, and thick solid line in the graph of Figure 7D are approximation curves that approximate the distribution of the measurement points of the coordinate correction rate in the x direction for sections Q1 to Q4. When focusing on one section, the error between the coordinate correction rate obtained from the approximation curve and the coordinate correction rate at multiple measurement points is small.

When the optical axis of the imaging device 40 is tilted with respect to the surface of the object to be measured, if the coordinates of the correction target area are corrected based on one approximation curve shown in FIG. 7C, the error between the corrected coordinates and the aberration-free coordinates will be large depending on the position of the correction target area. In response to this, in this embodiment, in step S1 (FIG. 4), two approximation curves that more accurately reflect the coordinate correction rate at the correction target area are selected from the four approximation curves shown in FIG. 7D.

Furthermore, in step S2 (FIG. 4), the coordinate correction rates obtained from the two approximation curves are weighted and averaged according to the degree to which the coordinate correction rate at the location to be corrected is reflected. Therefore, even if the optical axis of the imaging device 40 is tilted with respect to the surface of the object to be measured, the coordinates can be corrected using a coordinate correction rate that is close to the actual coordinate correction rate at the location to be corrected. This makes it possible to improve the accuracy of the coordinate correction.

Next, a modification of the above embodiment will be described.
In the above embodiment, the image surface 41 (FIG. 2) is divided into four sections Q1 to Q4, but the number of sections is not limited to four. The number of sections may be two or more. For example, in the example shown in FIG. 7D, the approximation curves of the sections Q1 and Q4 are mutually approximate, and the approximation curves of the sections Q2 and Q3 are mutually approximate. Therefore, even if the sections Q1 and Q4 are combined into one section, and the sections Q2 and Q3 are combined into one section, the coordinate correction accuracy can be maintained at a relatively high level.

In the above embodiment, the coordinate correction factors are calculated for a plurality of image points _P1 (FIG. 2) on the diagonal line of each of the four sections Q1 to Q4, and one approximation curve is set based on the coordinate correction factors. The plurality of image points _P1 on which the approximation curve is set may not be limited to those on the diagonal line, but may be set by taking into consideration the coordinate correction factors of other image points _P1 within the section.

For example, the coordinate correction ratio may be calculated for a plurality of image points _P1 in an area sandwiched between two radial directions extending from a reference point O into one section. In this case, in order to set one approximation curve that strongly reflects the coordinate correction ratios at the plurality of image points _P1 in the section, it is preferable to set the two radial directions so that the area sandwiched between the two radial directions includes the geometric center of the section.

In the above embodiment, when selecting two sections in step S1 (FIG. 4), two sections on both sides of the boundary line BL that, among the four boundary lines BL, forms the smallest angle with the direction from the reference point O toward the correction target point Pt are selected. Alternatively, two sections that closely approximate the coordinate correction rate at the correction target point Pt with high accuracy may be selected.

For example, in the example shown in FIG. 7D, the approximation curve for section Q1 and the approximation curve for section Q4 show similar trends with respect to changes in distance r. This means that when the correction target location Pt is located in section Q1 or section Q4, the coordinate correction rate at the correction target location Pt is approximated with high precision in section Q1 and section Q4. Therefore, when the correction target location Pt is located in section Q1 or section Q4, section Q1 and section Q4 may be selected as the two sections in step S1 (FIG. 4). For the same reason, when the correction target location Pt is located in section Q2 or section Q3, section Q2 and section Q3 may be selected as the two sections in step S1 (FIG. 4).

In the above embodiment, two sections are selected in step S1 (FIG. 4), but one section may be selected. For example, when the angle _θ1 (FIG. 3) is 0° or sufficiently small, only section Q1 may be selected. Whether one section or two sections are selected may be determined based on the magnitude of the angle _θ1 .

Next, an inkjet drawing device according to another embodiment will be described with reference to Figures 8A, 8B, and 9. The inkjet drawing device according to this embodiment is equipped with the distortion aberration correction device according to the embodiment shown in Figures 1 to 4.

Figure 8A is a schematic front view of the inkjet drawing device 20. A movable table 25 is supported on a base 22 by a moving mechanism 24. An xyz Cartesian coordinate system is defined in which the x-axis and y-axis are oriented horizontally and the z-axis is oriented vertically downward. The moving mechanism 24 is controlled by a control device 50 to move the movable table 25 in two directions, the x-direction and the y-direction. As the moving mechanism 24, for example, an XY stage including an X-direction moving mechanism 24X and a Y-direction moving mechanism 24Y can be used.

A substrate 80, which is the drawing target, is held on the upper surface of the movable table 25. The substrate 80 is fixed to the movable table 25, for example, by a vacuum chuck. An ink ejection unit 30 and an imaging device 40 are supported above the movable table 25, for example, by a gate-shaped support member 23.

The imaging device 40 captures an image of the top surface of the substrate 80. More specifically, it captures an image of a region of the top surface of the substrate 80 that is within the field of view of the imaging device 40. The image obtained by the imaging device 40 is input to the distortion aberration correction processing device 10.

The control device 50 receives position information of the substrate 80 from the distortion aberration correction processing device 10. Based on this position information, the control device 50 controls the movement mechanism 24 and the ink ejection unit 30 to cause ink to land at a predetermined position on the surface of the substrate 80. This forms an ink film of a predetermined shape on the surface of the substrate 80.

Figure 8B is a diagram showing the positional relationship of the movable table 25, the ink ejection unit 30, and the imaging device 40 in a plan view. A substrate 80 is held on the upper surface of the movable table 25. The ink ejection unit 30 and the imaging device 40 are supported above the substrate 80. A plurality of nozzles 32 are provided on the surface of the ink ejection unit 30 facing the substrate 80. The control device 50 controls the movement mechanism 24 to move the movable table 25 in the x and y directions, and also controls the ejection of ink from each nozzle 32 of the ink ejection unit 30.

Alignment marks 81 are formed at each of the four corners of the substrate 80. The control device 50 operates the movement mechanism 24 to position each of the alignment marks 81 within the field of view of the imaging device 40, allowing the imaging device 40 to capture an image of the alignment marks 81.

Figure 9 is a flow chart showing the procedure for drawing with the inkjet drawing device. First, the control device 50 operates the moving mechanism 24 to move one alignment mark 81 into the field of view of the imaging device 40 (step S11). After that, the imaging device 40 captures an image of the alignment mark 81 (step S12). The captured image data is input to the distortion aberration correction processing device 10. The distortion aberration correction processing device 10 analyzes the image of the alignment mark 81 to detect the coordinates of the image of the alignment mark 81 in the image plane (step S13). A known algorithm such as pattern matching can be used to detect the coordinates of the image of the alignment mark 81.

The distortion aberration correction processing device 10 corrects the coordinates of the image of the alignment mark 81 by executing the procedure according to the embodiment shown in FIG. 4 (step S14). The procedures from step S11 to step S14 are repeated until the coordinates of all alignment marks 81 have been corrected (step S15).

When the coordinate correction for all alignment marks 81 is completed, the distortion aberration correction processing device 10 passes the corrected coordinates of the images of the alignment marks 81 to the control device 50 (Figures 8A and 8B) (step S16). The control device 50 executes the drawing process based on the corrected coordinates of the images of the alignment marks 81 (step S17).

Next, the excellent effects of this embodiment will be described.
1 to 4, the inkjet drawing apparatus according to this embodiment is capable of measuring with high accuracy the position of the alignment mark 81. In particular, even if the optical axis of the imaging device 40 is inclined with respect to the surface of the substrate 80, a decrease in the measurement accuracy of the position of the alignment mark 81 can be suppressed.

Next, a modified example of the embodiment shown in Figures 8A to 9 will be described. In the embodiment shown in Figures 8A to 9, the distortion aberration correction processing device 10 according to the embodiment shown in Figures 1 to 4 is mounted on an inkjet drawing device, but the distortion aberration correction processing device 10 according to the embodiment shown in Figures 1 to 4 can also be mounted on other devices. For example, it can also be mounted on a laser processing device that irradiates a laser beam on an object to perform hole drilling, or a laser annealing device that irradiates a laser beam on a semiconductor substrate, which is an object, to perform annealing.

The above-described embodiments are merely examples, and it goes without saying that partial substitution or combination of the configurations shown in different embodiments is possible. Similar effects due to similar configurations in multiple embodiments will not be mentioned one by one. Furthermore, the present invention is not limited to the above-described embodiments. For example, it will be obvious to those skilled in the art that various modifications, improvements, combinations, etc. are possible.

REFERENCE SIGNS LIST 10 Distortion aberration correction processing device 11 Input/output interface unit 12 Processing unit 13 Storage unit 14 Program 15 Distortion aberration correction information 20 Inkjet drawing device 22 Base 23 Support member 24 Movement mechanism 24X X-direction movement mechanism 24Y Y-direction movement mechanism 25 Movable table 30 Ink ejection unit 32 Nozzle 40 Imaging device 41 Image surface of imaging device 50 Control device 80 Substrate 81 Alignment mark

Claims (5)

a storage unit in which, when an xy Cartesian coordinate system is defined on an image plane of an imaging device, distortion correction information is stored which indicates, for each of a plurality of sections divided by a plurality of boundaries extending radially from a reference point on the image plane, an x-coordinate correction factor for correcting an x-coordinate on the image plane, a y-coordinate correction factor for correcting a y -coordinate on the image plane, and a relationship with a distance from the reference point;
a processing unit that selects at least one section from the plurality of sections based on coordinates of a correction target section on the image plane, determines an x-coordinate correction rate and a y-coordinate correction rate based on the distortion aberration correction information for the selected section and a distance from the reference point to the correction target section, and corrects the coordinates of the correction target section based on the determined x-coordinate correction rate and y-coordinate correction rate. the shape of the image surface is square or rectangular;
the reference point is located at the center of the image plane;
2. The distortion aberration correction processing device according to claim 1, wherein the plurality of boundary lines are four line segments connecting the center of the image plane to the midpoints of the four sides. The processing unit, in the process of correcting the coordinates of the correction target portion,
selecting two sections on both sides of a boundary line that forms a smallest angle with a direction from the reference point toward the correction target portion from among the plurality of boundary lines;
3. The distortion aberration correction processing device according to claim 1, further comprising: a weighted average of x-coordinate correction rates and y-coordinate correction rates of the distortion aberration correction information for the two selected sections based on an angle between a direction from the reference point toward a geometric center of each of the two selected sections and a direction from the reference point toward the correction target location ; and a correction unit for correcting the coordinates of the correction target location based on the weighted average of the x-coordinate correction rate and the y-coordinate correction rate . an image of a measurement object is captured using an image capture device for which distortion aberration correction information indicating a relationship between an x- coordinate correction factor for correcting an x-coordinate in an image and a y-coordinate correction factor for correcting a y-coordinate in an image, and a distance from a reference point, for each of a plurality of sections divided by a plurality of boundaries extending radially from a reference point in the image plane of the image capture device, is known when an x-y orthogonal coordinate system is defined on an image plane of the image capture device;
determining a correction target location for correcting coordinates within the image plane;
selecting at least one section from the plurality of sections based on a position of the correction target portion within the image plane;
determining an x-coordinate correction rate and a y-coordinate correction rate based on the distortion aberration correction information for the selected section and the distance from the reference point to the correction target location;
The distortion aberration correcting method corrects the coordinates of the correction target portion based on the determined x-coordinate correction rate and y-coordinate correction rate . a step of acquiring an image of a measurement object captured using an imaging device for which distortion aberration correction information indicating a relationship between an x- coordinate correction factor for correcting an x-coordinate in an image and a y-coordinate correction factor for correcting a y-coordinate in an image, and a distance from a reference point, for each of a plurality of sections divided by a plurality of boundaries extending radially from a reference point in an image plane of an imaging device, when an x-y Cartesian coordinate system is defined on an image plane of the imaging device, is known;
A step of determining a correction target portion to be corrected from an image captured by the imaging device;
selecting at least one section from the plurality of sections based on coordinates of the correction target area in the image plane;
determining an x-coordinate correction rate and a y-coordinate correction rate based on the distortion aberration correction information for the selected section and a distance from the reference point to the correction target location;
and a step of correcting the coordinates of the correction target portion based on the determined x-coordinate correction rate and y-coordinate correction rate .

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