Liquid application device, method for applying liquid, and program

Abstract

To provide joint quality with a high image quality (quality of less joint step between images).SOLUTION: A liquid application device of sequentially moving to respective divided regions in which a liquid application region is divided into a plurality of pieces and applying liquid while connecting a plurality of images includes: an imaging device that is disposed in a position facing ends of the divided regions to image a reference position that is set to a region where the ends of the divided regions overlap one another; and an image joint measurement part for setting the reference position that is imaged by the imaging device as a reference origin of writing an image.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a liquid application device, a liquid application method, and a program. [Background technology]

[0002] Conventionally, in a self-propelled painting device that prints white lines, letters, symbols, etc. on road surfaces, a technique has been known in which, when painting (printing) a large image, the image is divided into multiple parts and then stitched together. With this technique, errors in the continuity of the image can occur as the painting device moves, making the seams conspicuous, and the estimation of the painting device's self-position significantly affects the image quality.

[0003] As a method for estimating the self-position of a painting device, for example, the following method is already known. (1) A method of estimating the current position from the direction and rotation of the tires using a speed detector (odometry) (2) Estimating self-position using GNSS (Global Navigation Satellite System) (3) A method of estimating the vehicle's position from images of the road, floor, ceiling, and scenery captured by a camera and map information.

[0004] Patent document 1 discloses a device for reproducing images etc. on a large surface, which comprises a printing system that moves relative to a support frame and an optical observation system mounted on the support frame to enable correct positioning of adjacent parts that must then be produced. Summary of the Invention [Problem to be solved by the invention]

[0005] However, with conventional technology, when stitching together images, the four corners of the area captured by one camera are extracted and used as reference points. Therefore, if the plane angle with the road surface is shifted due to distortion of the lens or tilt of the painting equipment itself due to unevenness of the road surface, the paint landing position will be shifted, resulting in distortion of the printed image of the road surface.

[0006] The present invention has been made in view of the above, and has as its object to achieve high-quality seams (quality with fewer seam gaps between images). [Means for solving the problem]

[0007] In order to solve the above-mentioned problems and achieve the object, the present invention provides a liquid application device that divides a liquid application area into multiple areas, moves sequentially to each divided area, and applies liquid by connecting multiple images, and is characterized by comprising: an imaging device that is positioned opposite the end of the divided area and captures an image of a reference position set in an area where the ends of the divided areas overlap; and an image connection measurement unit that uses the reference position captured by the imaging device as the reference origin for writing an image. [Effects of the Invention]

[0008] The present invention has the effect of realizing high-quality seams (quality with fewer seam gaps between images). [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram showing the configuration of a liquid application apparatus according to the first embodiment. [Figure 2] FIG. 2 is a block diagram showing the hardware configuration of the arithmetic unit of the liquid application device. [Figure 3] FIG. 3 is a diagram showing an example in which the liquid application device prints outside the carriage scanning range. [Figure 4] FIG. 4 is a diagram showing an example of the shape of the divided regions. [Figure 5] FIG. 5 is a diagram showing an example of a four-point reference jig plate. [Figure 6] FIG. 6 is a flowchart showing the workflow of calibration using a four-point reference jig plate. [Figure 7] FIG. 7 is a diagram showing an example of a captured image when photographing a jig. [Figure 8] FIG. 8 is a diagram showing an example of an image captured when a measuring tape is used. [Figure 9] FIG. 9 is a functional block diagram showing the functions performed by the liquid application device. [Figure 10] FIG. 10 is a flowchart showing the flow of processing for joining print areas. [Figure 11] FIG. 11 is a diagram for explaining the operation of aligning the reference point of the print area (segment 1). [Figure 12] FIG. 12 is a diagram for explaining the operation of aligning the reference point of the print area (segment 2). [Figure 13] FIG. 13 is a diagram for explaining the operation of overlapping the print areas (segments 1 and 2). [Figure 14] FIG. 14 is a diagram for explaining the problems of the conventional example. [Figure 15] FIG. 15 is a diagram showing a two-dimensional camera provided in the liquid application apparatus according to the second embodiment. [Figure 16] FIG. 16 is a diagram showing a two-dimensional camera provided in the liquid application apparatus according to the third embodiment. [Figure 17] FIG. 17 is a diagram showing a two-dimensional camera provided in the liquid application apparatus according to the fourth embodiment. [Figure 18] FIG. 18 is a diagram showing a two-dimensional camera 7 provided in the liquid application apparatus according to the fifth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a liquid application device, a liquid application method, and a program will be described in detail with reference to the accompanying drawings.

[0011] (First embodiment) FIG. 1 is a diagram showing the configuration of a liquid application device 1 according to a first embodiment. FIG. 1(a) is a side view of the liquid application device 1, and FIG. 1(b) is a plan view of the liquid application device 1 as seen from above. The liquid application device 1 shown in FIG. 1 is a liquid application device that divides a wide printing area such as a road surface or a wall surface into multiple sections and moves sequentially to each of the divided sections, and prints large shapes (patterns, symbols, lines, etc.) by dividing them into multiple segments. Note that "printing" refers to applying or spraying a liquid onto a road, wall surface, etc.

[0012] 1, liquid application apparatus 1 includes a printing unit 21 and a control unit 22. Printing unit 21 of liquid application apparatus 1 includes an ink ejection head (carriage head) 2, which is a liquid ejection head that ejects ink to perform printing. Note that although liquid application apparatus 1 of the present embodiment includes printing unit 21 and control unit 22, the system may also be configured such that printing unit 21 and control unit 22 are separate entities.

[0013] The ink ejection head (carriage head) 2 is provided with a large number of nozzles for a single color or multiple colors. Note that "ink" is a liquid that is applied or sprayed onto roads, walls, etc.

[0014] The printing unit 21 has a gantry structure in which an ink ejection head (carriage head) 2 is movable in the direction of arrow A (main scanning direction) on rails (main scanning support mechanism) 3 provided horizontally on a housing 11.

[0015] The printing unit 21 has a plurality of tires 10 and a motor 20 (see FIG. 2) mounted on the bottom of the housing 11. The printing unit 21 can move in four directions (front, back, left, and right) by controlling the rotation of the tires 10 with the motor 20. In other words, the printing unit 21 can move freely on the road surface by controlling the rotation of the tires 10 with the motor 20.

[0016] The ink ejection head (carriage head) 2 is equipped with a head movement mechanism 23 (see FIG. 2) that uses a timing belt, ball joints, pulleys, a drive motor, etc. The ink ejection head (carriage head) 2 is moved back and forth in the direction of arrow A along a rail 3 of the printing unit 21 by the head movement mechanism 23. The rail 3 is equipped with a rail movement mechanism 24 (see FIG. 2) that uses a timing belt, ball joints, pulleys, a drive motor, etc. The rail 3 is moved back and forth along the housing 11 of the printing unit 21 by the rail movement mechanism 24 in the sub-scanning direction, which is a direction perpendicular to the longitudinal direction of the rail 3 (the direction of arrow B). In other words, the ink ejection head (carriage head) 2 can move freely in the horizontal direction within the housing 11 of the liquid application device 1 in the left-right direction (main scanning direction) that is the direction of arrow A and the front-back direction (sub-scanning direction) that is the direction of arrow B.

[0017] The control unit 22 of the liquid application device 1 also includes an ink supply system 4 that supplies ink used for printing to the ink ejection head (carriage head) 2. The ink supply system 4 is connected to the ink ejection head (carriage head) 2 via a pipe 4a, which is an ink flow path. In this embodiment, the ink supply system 4 moves in conjunction with the printing unit 21, but this is not limiting and the ink supply system 4 may also move independently of the printing unit 21.

[0018] Furthermore, the control unit 22 includes a calculation device 6 that controls the driving of the head movement mechanism 23, rail movement mechanism 24, motor 20, and ink ejection head (carriage head) 2 of the printing unit 21, and estimates the self-position of the liquid application device 1 from coordinate data acquired by the GPS 9. The calculation device 6 also generates images when stitching together images, as will be described in detail later.

[0019] The control unit 22 also includes a power supply system 5 that supplies power to drive the arithmetic device 6, the head movement mechanism 23 of the printing unit 21, the rail movement mechanism 24, the motor 20, and the ink ejection head (carriage head) 2. The power supply system 5 is used externally and is preferably a large-capacity storage battery because it also supplies power to components other than the arithmetic device 6, the head movement mechanism 23 of the printing unit 21, the rail movement mechanism 24, the motor 20, and the ink ejection head (carriage head) 2.

[0020] Furthermore, the printing unit 21 is equipped with two-dimensional cameras 7 (7A, 7B, 7C, 7D) at each end (four locations) of the printing area in the housing 11, which are imaging devices for photographing the road surface and the vicinity of the painted image. The two-dimensional cameras 7 transmit the captured images to the computing device 6. The computing device 6 uses the images captured by the two-dimensional cameras 7 to estimate the movement amount and speed of the ink ejection head (carriage head) 2 and the rail 3 using techniques such as image correlation. The two-dimensional cameras 7 are powered by their own built-in batteries, but may be powered by the power supply system 5 in case of continuous operation.

[0021] The two-dimensional camera 7 for photographing the road surface extracts reference points (feature points within the image capture area of ​​the two-dimensional camera 7) on the road surface image data before the liquid application device 1 moves, and after the liquid application device 1 moves, another two-dimensional camera 7 performs template matching processing to search for the feature points before the movement. More specifically, the liquid application device 1 is moved to the image writing position (this can be done manually or by a moving device not shown), and printing is performed within the first segment area. Thereafter, the liquid application device 1 is moved to the adjacent second segment area, and the adjacent image is printed. The calculation device 6 determines and sets the reference points at this time from the images captured by the four two-dimensional cameras 7.

[0022] Furthermore, the liquid application apparatus 1 is equipped with a GPS (Global Positioning System) 9 that measures the current position on Earth. The GPS 9 transmits the acquired coordinate data to the calculation device 6. The calculation device 6 stores the coordinate data acquired by the GPS 9 as odometry information such as the accumulated movement amount of the liquid application apparatus 1. Note that the liquid application apparatus 1 may be equipped with a plurality of GPS 9, and the calculation device 6 may correct errors in the coordinate data based on differences in the coordinate data acquired by the plurality of GPS 9.

[0023] Next, the hardware configuration of the arithmetic unit 6 of the liquid application apparatus 1 will be described.

[0024] Here, Fig. 2 is a block diagram showing the hardware configuration of the arithmetic device 6 of the liquid application apparatus 1. As shown in Fig. 2, the arithmetic device 6 has a CPU (Central Processing Unit) 61, memory 62 which is a ROM (Read Only Memory) and a RAM (Random Access Memory), an input / output interface (I / F) 63, and a unit control circuit 64. These are connected to each other via a system bus.

[0025] The CPU 61 comprehensively controls the operation of the liquid application device 1. The CPU 61 controls the driving of the head movement mechanism 23, rail movement mechanism 24, motor 20, and ink ejection head (carriage head) 2 of the printing unit 21 via the unit control circuit 64, and estimates the self-position of the liquid application device 1 from coordinate data acquired by the GPS 9.

[0026] Furthermore, the CPU 61 uses the images captured by the two-dimensional camera 7 by using techniques such as image correlation to estimate the movement amount and speed of the ink ejection head (carriage head) 2 and the rail 3. The CPU 61 saves the coordinate data acquired by the GPS 9 as odometry information such as the cumulative movement amount of the liquid application device 1.

[0027] The memory 62 stores programs used to drive the CPU 61. The memory 62 is also used as a work area for the CPU 61.

[0028] The I / F 63 is an interface for connecting various external devices 30 such as a tablet terminal, a smartphone, a personal computer, a server, and a notebook PC (Personal Computer).

[0029] As described above, the liquid application device 1 is movable in four directions: front, back, left, and right. In addition, the ink ejection head (carriage head) 2 can scan within the housing 11 of the liquid application device 1 in four directions: front, back, left, and right, to perform printing.

[0030] 3 is a diagram showing an example of printing outside the carriage scanning range by the liquid application device 1. When printing an image outside the scanning range of the ink ejection head (carriage head) 2, the liquid application device 1 divides the entire image into multiple rectangular (quadrangular) segments (divided areas) as shown in Fig. 3, and completes the image by moving the liquid application device 1 and creating overlapping areas between the images of adjacent segments.

[0031] In this embodiment, the segments, which are divided regions, have been described as being rectangular, but this is not limiting. Fig. 4 shows examples of the shapes of the divided regions. Fig. 4(a) shows an example of a triangular divided region shape, Fig. 4(b) shows an example of a square (quadrilateral) divided region shape, and Fig. 4(c) shows an example of a hexagonal divided region shape. In the example shown in Fig. 4(a), two-dimensional cameras 7 are provided at three locations facing the ends of the triangle, in the example shown in Fig. 4(b), two-dimensional cameras 7 are provided at four locations facing the ends of the square (quadrilateral), and in the example shown in Fig. 4(c), two-dimensional cameras 7 are provided at six locations facing the ends of the hexagon.

[0032] As described above, in this embodiment, the segments that are the divided areas are quadrilateral (rectangle), and four two-dimensional cameras 7 are placed at the ends of the quadrilateral. This has the advantage that it is easy to create the divided areas and also easy to deal with the scanning directions (main scanning, sub-scanning) of the ink ejection head (carriage head) 2.

[0033] Here, the alignment of the two-dimensional cameras 7 themselves, that is, the setting of the distance between the two-dimensional cameras 7, will be described.

[0034] Here, Fig. 5 is a diagram showing an example of a four-point reference jig plate 200. As shown in Fig. 5, before operation, the origin of each two-dimensional camera 7 is set using the reference jig plate 200 that indicates (confirms) the mounting position of each two-dimensional camera 7. As shown in Fig. 5, the reference jig plate 200 has reference points Y at each of the four corners.

[0035] Fig. 6 is a flowchart showing the workflow of calibration using the four-point reference jig plate 200. As shown in Fig. 6, in the calibration work for the mounting position of the two-dimensional camera 7, first, the reference jig plate 200 shown in Fig. 5 is set on the coating surface below the liquid application device 1 (step S101).

[0036] Next, the liquid applicator 1 simultaneously captures images using the four two-dimensional cameras 7 of the liquid applicator 1 (step S102).

[0037] 7 is a diagram showing an example of an image captured when photographing the jig. As shown in Fig. 7, the liquid application device 1 obtains the position of the reference point Y on the photographed data photographed by each two-dimensional camera 7 (step S103).

[0038] Next, the liquid application device 1 calculates the difference between the position of the reference point Y on the photographed data captured by each two-dimensional camera 7 and the center of the two-dimensional camera 7 (step S104). More specifically, the difference is obtained from the position of the reference point Y on the photographed data captured by each two-dimensional camera 7 and the actual distance (L11, L12) between the two-dimensional cameras 7. For example, the difference between the distance between the position of the reference point Y on the photographed data captured by two-dimensional camera 7A and the position of the reference point Y on the photographed data captured by two-dimensional camera 7B and the reference distance L11 is obtained.

[0039] Next, the liquid application apparatus 1 stores the obtained difference values ​​in memory as deviation amounts (step S105). When calculating position coordinates, the liquid application apparatus 1 uses the deviation amounts to calculate distances.

[0040] As a result, by simultaneously setting the origins of the two-dimensional cameras 7 before printing, the distance between the two-dimensional cameras 7 can be corrected, and detection errors can be avoided.

[0041] In this embodiment, the origin of each two-dimensional camera 7 is set using a reference jig plate 200 that confirms the mounting position of each two-dimensional camera 7 before operation, but this is not limited to this. For example, the origin position of the two-dimensional camera 7 may be adjusted using the distance between two two-dimensional cameras 7 measured in advance. Here, FIG. 8 is a diagram showing an example of an image captured using a tape measure. As shown in FIG. 8, by measuring the distance between the images captured by the two two-dimensional cameras 7 with a tape measure M before printing and adjusting the origin, the distance between the two-dimensional cameras 7 can be corrected and detection errors can be avoided.

[0042] Furthermore, a trial piece of stitching may be performed before operation, and the stitching accuracy in the imaging area of ​​the two-dimensional camera 7 may be measured using an image. Calibration may then be performed using the stitching accuracy results. This method does not require jigs or measuring tapes, and the origin position of each two-dimensional camera 7 can be adjusted (calibrated) using the stitching accuracy from the trial piece of stitching, thereby avoiding detection errors.

[0043] Next, the characteristic functions that the liquid application device 1 exhibits during the above-mentioned printing process will be described.

[0044] 9 is a functional block diagram showing functions performed by liquid application apparatus 1. All or any part of the processing functions performed by each functional block shown in FIG. 9 may be realized by a program executed by CPU 61 of the above-mentioned arithmetic device 6, or may be realized by hardware such as wired logic.

[0045] 9, in order to divide an entire image into a plurality of segments and print them, the calculation device 6 of the liquid application device 1 includes an image processing unit 50 and an image creating unit 55. The image processing unit 50 includes an image generation calculation unit 51, a template matching calculation unit 52, and an image stitching measurement unit 53. The image creating unit 55 includes a movement control unit 56 and a head control unit 57.

[0046] The image generation calculation unit 51 generates image data for the amount that can be printed in the area of ​​segment 1.

[0047] The template matching calculation unit 52 extracts reference points (feature points within the image capture area of ​​the two-dimensional camera 7) on the road surface image data before the movement of the liquid application device 1, and then performs template matching processing to search for the feature points before the movement using another two-dimensional camera 7 after the movement of the liquid application device 1. More specifically, the liquid application device 1 is moved (this can be done manually or by a moving device not shown) to the image writing position, and printing is performed within the first segment area. Thereafter, the liquid application device 1 is moved to the adjacent second segment area, and the adjacent image is printed. The calculation unit 6 determines and sets the reference points at this time from the images captured by the four two-dimensional cameras 7.

[0048] The movement control unit 56 controls the sequential movement of the liquid application device 1 to each of the divided regions obtained by dividing the liquid application region where liquid is applied by the ink ejection head (carriage head) 2. More specifically, the movement control unit 56 controls the sequential movement of the liquid application device 1 to adjacent or partially overlapping divided regions.

[0049] The head control unit 57 controls the movement of the ink ejection head (carriage head) 2 in the XY scanning directions in each divided area to apply liquid. If there is no application data for the divided area, the head control unit 57 does not execute the liquid application operation. In this way, when the head control unit 57 does not execute the liquid application operation because there is no application data for the divided area, the movement control unit 56 controls movement to the next adjacent or partially overlapping area.

[0050] The image stitching measurement unit 53 uses four two-dimensional cameras 7 positioned above (opposite) the ends of the divided areas, which are obtained by dividing the entire image into multiple segments, to read reference positions (image writing start positions) set in areas where the ends of the divided areas overlap, and sets these as the reference origin for image writing. Here, the ends of the divided areas are the ends of the head operating range of the ink ejection head (carriage head) 2. Alternatively, the ends of the divided areas are near the optical axes of the optical systems of the two-dimensional cameras 7.

[0051] The coordinate measurement unit 52 measures the self-position coordinates (position and attitude) of the liquid application device 1 using a self-position estimation technology that combines GNSS (Global Navigation Satellite System) measurement using GPS 9 and images (surrounding image data) captured by the three-dimensional camera 7.

[0052] The following describes the process of joining print areas in the printing process in which an image is completed while the liquid application device 1 is moved.

[0053] 10 is a flowchart showing the flow of the process of joining print areas in the calculation device 6. This is a flowchart showing the flow of the joining process.

[0054] First, the movement control unit 56 moves the liquid application device 1 to the printing position (segment 1) (step S1).

[0055] Next, the image generation calculation unit 51 generates print image data (step S2).

[0056] Next, the head control unit 57 performs printing with reference to the printing reference point (step S3).

[0057] Next, the image connection measurement unit 53 acquires (acquisition 1) a road surface image using four two-dimensional cameras 7 positioned above the ends of the divided area (at positions opposite the ends) (step S4), extracts feature points from the road surface image (step S5), and calculates the feature point connection distance Lb from the feature points (step S6).

[0058] Fig. 11 is a diagram illustrating the operation of aligning the reference points in the printing area (segment 1). Fig. 11 illustrates the operation of the image stitching measurement unit 53 when stitching images together, in the case where the liquid application device 1 is placed in the first coating area (segment 1).

[0059] First, the liquid application device 1 controls the image generation calculation unit 51 to generate image data for the amount that can be printed in the area of ​​segment 1. After that, the liquid application device 1 performs printing and coating using the printing reference point O1 of segment 1 as the origin.

[0060] Next, the liquid application device 1 acquires a road surface image using the two-dimensional camera 7 placed at the end of the working area of ​​the segment 1 (acquisition 1).

[0061] Next, liquid application device 1 extracts road surface characteristic points from the acquired road surface image. In the example shown in Fig. 11, the vehicle next moves in the direction of segment 2, so extraction of road surface characteristic point X is performed within the imaging areas of two-dimensional camera 7B and two-dimensional camera 7D.

[0062] Then, the liquid application device 1 calculates the feature point connection distance Lb (Lb=La-L1), which is the distance between the feature point and the seam, based on the feature point distance La, which is the distance from the extracted road surface feature point X to the printing reference point, and the reference distance L1, which is the distance from the seam at the end of the image to the printing reference point.

[0063] Returning to FIG. 10, the movement control unit 56 moves the liquid application device 1 to the printing position (segment 2) (step S11).

[0064] Next, the image generation calculation unit 51 generates print image data (step S12).

[0065] Next, the image connection measurement unit 53 acquires (acquires 1) a road surface image using four two-dimensional cameras 7 positioned above the ends of the divided area (at positions opposite the ends) (step S13), extracts feature points from the road surface image in the connection direction (step S14), and sets the print start point at the feature point connection distance Lb calculated from the feature points (step S15).

[0066] Next, the head control unit 57 performs printing with reference to the printing reference point (step S16).

[0067] Next, the image connection measurement unit 53 acquires (acquisition 2) a road surface image using four two-dimensional cameras 7 positioned above the ends of the divided area (at positions opposite the ends) (step S17), extracts feature points from the road surface image (step S18), and calculates the feature point connection distance Lb from the feature points (step S19).

[0068] Thereafter, the movement control unit 56 moves the liquid application device 1 to the printing position (segment 3) (step S20). The process is repeated thereafter.

[0069] 12 is a diagram illustrating the operation of aligning the reference point of the printing area (segment 2). In FIG. 12, the liquid application device 1 is moved to segment 2.

[0070] First, the liquid application device 1 controls the image generation calculation unit 51 to generate image data for the amount that can be printed in the area of ​​the segment 2.

[0071] Next, the liquid application device 1 uses a two-dimensional camera 7 placed at the end of the working area of ​​the segment 2 to acquire an image of the road surface.

[0072] Next, liquid application device 1 extracts road surface characteristic points from the road surface image. In the example shown in Fig. 12, extraction of road surface characteristic points X is carried out within the imaging areas of two-dimensional camera 7A and two-dimensional camera 7C.

[0073] Next, the liquid application device 1 sets the print start point O2 for segment 2 using the extracted road surface characteristic point X and the characteristic point connection distance Lb calculated earlier.

[0074] Thereafter, the liquid application device 1 performs printing and coating, with the printing start point O2 of the segment 2 as the origin.

[0075] Next, the liquid application device 1 uses the two-dimensional camera 7 arranged at the end of the working area of ​​the segment 2 to acquire road surface images in the direction of further movement (acquisition 2).

[0076] Next, liquid application device 1 extracts feature points from the acquired road surface image. In the example shown in Fig. 12, the vehicle next moves in the direction of segment 3, so extraction of road surface feature point X is performed within the imaging areas of two-dimensional camera 7B and two-dimensional camera 7D.

[0077] Then, the liquid application device 1 calculates the feature point connection distance Lb (Lb=La-L1), which is the distance between the feature point and the seam, based on the feature point distance La, which is the distance from the extracted road surface feature point X to the printing reference point, and the reference distance L1, which is the distance from the seam at the end of the image to the printing reference point.

[0078] Thereafter, the liquid application device 1 moves to the next segment 3 and repeats the same operation flow. In this way, individual images can be generated one on top of the other, providing a large coating area.

[0079] In Figures 11 and 12, road surface characteristics are photographed with each two-dimensional camera 7 to extract road surface feature points X, but feature amounts are extracted and determined from the colors that make up the road surface, the arrangement and distribution of stones, sand, asphalt, etc., and printed painted surfaces.

[0080] Here, Figure 13 is a diagram explaining the operation of overlapping the printing areas (segments 1 and 2). Figure 13 shows the positions of the liquid application device 1 in segments 1 and 2, and the results of printing and painting. As shown in Figure 13, by aligning the road surface feature points of both segments 1 and 2, a clear printed image is generated when they are overlapped.

[0081] Fig. 14 is a diagram illustrating the problems of the conventional example. The conventional liquid application device 100 shown in Fig. 14(a) has only one two-dimensional camera 101, which captures images of the road surface and the vicinity of the painted image, at the vertex of a structure 102 made of pipes or the like arranged in a quadrangular pyramid shape.

[0082] With the conventional liquid application device 100, when stitching together images, the four corners of the area captured by one two-dimensional camera 101 are extracted and used as reference points, so reading position errors occur due to lens distortion aberration and tilt of the coating device itself due to road surface unevenness.

[0083] 14(b) is an enlarged view of the reading position error when the road surface is convex. As shown in FIG. 14(b), when the angle of view of the image capturing area of ​​the two-dimensional camera 101 is θ, the reading detection error e1 due to the road surface convexity amount δ is expressed as follows: e1=δtan(θ / 2) Furthermore, if segment 2 is set based on the reading position with this reading detection error e1, a setting position error e2 will be added.

[0084] Ultimately, the distance between the position (center of the imaging area) of the two-dimensional camera 101 in segment 1 (before movement) and the center of the two-dimensional camera 101 in segment 2 (after movement) results in an error of e1 + e2. The detection position error due to road surface unevenness increases as the camera 101 tilts away from the center of its lens.

[0085] Fig. 14(c) is a diagram illustrating a reading position error due to lens distortion. As shown in Fig. 14(c), when the edge of the print area is photographed with the camera lens of one two-dimensional camera 101, a reading position error occurs due to the distortion aberration of the camera lens of the two-dimensional camera 101. Camera lens distortion of the two-dimensional camera 101 is likely to occur at the edge of the angle of view.

[0086] In this regard, by arranging two-dimensional cameras 7 (for example, four cameras in total) above the seam reference points at the image edges as in this embodiment, all seam reference points are located near the center of the camera lens of the two-dimensional camera 7, making them less susceptible to distortion of the two-dimensional camera 7 lens and less likely to cause deviations in detected positions due to road surface irregularities. This makes it possible to detect and recognize seam reference points with high accuracy.

[0087] According to this embodiment, in large-area painting where multiple images are printed continuously on the road surface, two-dimensional cameras 7 are placed at each of the four edges of the printing area (nearly directly above the seam reference points at the image edges) to eliminate the above-mentioned adverse effects, and the liquid application device 1 detects and recognizes the seam reference points (four locations at the image edges) with high precision, and uses the seam reference points to stitch the images, thereby avoiding the above-mentioned reading position error. This achieves high-quality seam quality (quality with minimal seam gaps between images) and makes it possible to provide high-precision painting where image seams are less noticeable.

[0088] Furthermore, according to this embodiment, the size of the liquid application device 1 itself in the height direction can be reduced, which is advantageous in terms of size and weight reduction, and is also advantageous in terms of transportation to and handling on site.

[0089] In this embodiment, the segments that are divided areas are quadrangles (rectangles), and four two-dimensional cameras 7 are placed at the ends of the quadrangles, but the number of two-dimensional cameras 7 is limited by the direction in which they are connected when divided for large-area printing. For example, if the area is long and narrow like a strip, it is not necessary to place four two-dimensional cameras 7, and two two-dimensional cameras 7 may be sufficient.

[0090] Furthermore, one two-dimensional camera 101 provided in the conventional liquid application device 100 shown in FIG. 14 may be left and used to check the image printing.

[0091] (Second embodiment) Next, a second embodiment will be described.

[0092] The second embodiment differs from the first embodiment in that the two-dimensional camera 7 is provided with an automatic dustproof cover mechanism that protects the camera lens when not taking pictures. In the following description of the second embodiment, the same parts as in the first embodiment will be omitted, and only the differences from the second embodiment will be described.

[0093] 15 is a diagram showing the two-dimensional camera 7 provided in the liquid application device 1 according to the second embodiment. As shown in Fig. 15, the two-dimensional camera 7 is provided with an automatic dustproof cover mechanism 7b that protects the camera lens 7a, which is an optical system. The two-dimensional camera 7 drives the automatic dustproof cover mechanism 7b to protect the camera lens 7a when not taking pictures.

[0094] As described above, according to this embodiment, the camera lens 7a of the two-dimensional camera 7 is closer to the road surface, which prevents dust and other particles from the road surface from adhering to the camera lens 7a and causing detection errors.

[0095] (Third embodiment) Next, a third embodiment will be described.

[0096] The third embodiment differs from the first or second embodiment in that the two-dimensional camera 7 is equipped with an LED light (flash). In the following description of the third embodiment, the description of the same parts as the first or second embodiment will be omitted, and only the parts that differ from the third embodiment will be described.

[0097] 16 is a diagram showing the two-dimensional camera 7 provided in the liquid application device 1 according to the third embodiment. As shown in Fig. 16, the two-dimensional camera 7 is provided with an LED light (flash) 7c. When capturing an image, the two-dimensional camera 7 maintains constant road surface illuminance by emitting light from the LED light (flash) 7c.

[0098] As described above, according to this embodiment, the camera lens 7a of the two-dimensional camera 7 is closer to the road surface, so it is possible to avoid detection errors due to reading errors caused by shadows or the like, as the road surface becomes dark when viewed from the camera lens 7a. In addition, it is possible to flexibly respond to changes in sunlight, such as on cloudy days or in the evening.

[0099] (Fourth embodiment) Next, a fourth embodiment will be described.

[0100] The fourth embodiment differs from the first to third embodiments in that it is equipped with an automatic air blower that blows air toward the camera lens 7a of the two-dimensional camera 7. In the following explanation of the fourth embodiment, explanations of the same parts as the first to third embodiments will be omitted, and only differences from the fourth embodiment will be explained.

[0101] 17 is a diagram showing the two-dimensional camera 7 provided in the liquid application device 1 according to the fourth embodiment. As shown in Fig. 17, the two-dimensional camera 7 is provided with an automatic air blower 7d that blows air toward the camera lens 7a, which is an optical system. When capturing an image, the two-dimensional camera 7 blows air from the automatic air blower 7d toward the camera lens 7a.

[0102] As described above, according to this embodiment, the camera lens 7a of the two-dimensional camera 7 is closer to the road surface, which prevents dust and other particles from the road surface from adhering to the camera lens 7a and causing detection errors.

[0103] (Fifth embodiment) Next, a fifth embodiment will be described.

[0104] The fifth embodiment differs from the first to fourth embodiments in that the two-dimensional camera 7 is provided with an automatic air blower that blows air toward the road surface. In the following explanation of the fifth embodiment, explanations of the same parts as the first to fourth embodiments will be omitted, and only differences from the fifth embodiment will be explained.

[0105] Here, Fig. 18 is a diagram showing the two-dimensional camera 7 provided in the liquid application device 1 according to the fifth embodiment. As shown in Fig. 18, the two-dimensional camera 7 is provided with an automatic air blower 7e that blows air toward the road surface. When capturing an image, the two-dimensional camera 7 blows air from the automatic air blower 7e toward the road surface.

[0106] As described above, according to this embodiment, the camera lens 7a of the two-dimensional camera 7 is closer to the road surface, so that dust and other debris on the road surface can be blown away with compressed air, thereby avoiding detection errors caused by dust and other debris.

[0107] The programs executed by the liquid application apparatus 1 of each embodiment are provided in advance in a ROM or the like.

[0108] The program executed by the liquid application device 1 of each embodiment may be configured to be provided by being recorded in an installable or executable file format on a computer-readable recording medium such as a CD-ROM, a flexible disk (FD), a CD-R, or a DVD (Digital Versatile Disc).

[0109] Furthermore, the program executed by the liquid application apparatus 1 of each embodiment may be stored on a computer connected to a network such as the Internet and provided by being downloaded via the network. Also, the program executed by the liquid application apparatus 1 of each embodiment may be provided or distributed via a network such as the Internet.

[0110] In this application, a "liquid application device" is a device that includes a liquid ejection head or a liquid ejection unit and ejects liquid by driving the liquid ejection head. Liquid application devices include not only devices that can eject liquid onto objects to which the liquid can adhere, but also devices that eject liquid into air or liquid.

[0111] This "liquid application device" can also include means for feeding, transporting, and discharging items onto which liquid can be applied, as well as pre-processing devices and post-processing devices.

[0112] For example, examples of "liquid application devices" include image forming devices, which are devices that eject ink to form images on paper, and three-dimensional modeling devices (three-dimensional modeling devices), which eject modeling liquid onto a powder layer formed from powder in layers in order to create a three-dimensional object (a three-dimensional model).

[0113] Furthermore, the term "liquid application device" is not limited to devices that use ejected liquid to visualize meaningful images such as letters and figures. For example, it also includes devices that form patterns that have no meaning in themselves, and devices that create three-dimensional images.

[0114] The above-mentioned "object onto which a liquid can adhere" means an object onto which a liquid can adhere at least temporarily, an object onto which the liquid can adhere and stick, an object onto which the liquid can penetrate, etc. Specific examples include media such as paper, recording paper, film, and cloth, electronic circuit boards, electronic components such as piezoelectric elements, powder layers, organ models, and test cells, and unless otherwise specified, includes all objects onto which a liquid can adhere.

[0115] The material of the "substance to which a liquid can adhere" may be any material to which a liquid can adhere, even temporarily, such as paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, or ceramics.

[0116] The "liquid" is not particularly limited as long as it has a viscosity and surface tension that allows it to be ejected from a head, but it is preferably one whose viscosity is 30 mPa·s or less at room temperature and normal pressure, or upon heating or cooling. More specifically, it is a solution, suspension, emulsion, etc. containing a solvent such as water or an organic solvent, a colorant such as a dye or pigment, a functionalizing material such as a polymerizable compound, a resin, or a surfactant, a biocompatible material such as DNA, amino acids, proteins, or calcium, or an edible material such as a natural colorant. These can be used, for example, as inkjet inks, surface treatment liquids, liquids for forming components of electronic devices or light-emitting elements, or electronic circuit resist patterns, and material liquids for 3D modeling.

[0117] Furthermore, the term "liquid application device" includes, but is not limited to, a device in which a liquid ejection head and an object onto which liquid can be applied move relatively. Specific examples include a serial type device in which the liquid ejection head moves, and a line type device in which the liquid ejection head does not move.

[0118] Other examples of "liquid application devices" include treatment liquid application devices that eject treatment liquid onto paper to apply the treatment liquid to the surface of the paper for purposes such as modifying the surface of the paper, and spray granulation devices that spray a composition liquid in which raw materials are dispersed through a nozzle to granulate fine particles of the raw materials.

[0119] Finally, the above-described embodiment is presented as an example and is not intended to limit the scope of the present invention. This novel embodiment can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. Furthermore, the embodiment and modifications thereof are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims.

[0120] For example, aspects of the present invention are as follows. <1> A liquid application device that divides a liquid application area into a plurality of areas, sequentially moves to each divided area, and applies liquid to a plurality of images while connecting them together, an imaging device that is disposed at a position facing the end of the divided area and captures an image of a reference position set in an area where the end portions of the divided areas overlap; an image stitching measurement unit that sets a reference position captured by the imaging device as a reference origin for image writing; A liquid application device comprising: <2> the end of the divided region is the end of a head operation range of the liquid ejection head; Characterized by <1> The liquid application device according to claim 1. <3> an end of the divided region is near the optical axis of the optical system of the imaging device; Characterized by <1> The liquid application device according to claim 1. <4> The divided regions are rectangular, Four of the imaging devices are arranged at the ends of the rectangular divided area. Characterized by <1> Or <3> 10. The liquid application device according to claim 9, wherein <5> The distance between the imaging devices is set by simultaneously setting the origins of the imaging devices using a reference plate jig indicating the mounting position before operation. Characterized by <1> Or <4> 10. The liquid application device according to claim 9, wherein <6> The distance between the imaging devices is set by measuring the joining accuracy of a test joining print using an image before operation and adjusting the origin positions of the imaging devices. Characterized by <1> Or <4> 10. The liquid application device according to claim 9, wherein <7> The distance between the imaging devices is set by adjusting the origin positions of the imaging devices using a distance between the two imaging devices measured in advance. Characterized by <1> Or <4> 10. The liquid application device according to claim 9, wherein <8> The imaging device is provided with an automatic dust cover mechanism that protects the optical system of the imaging device when not taking pictures. Characterized by <1> Or <7> 10. The liquid application device according to claim 9, wherein <9> The imaging device is provided with a light that emits light to keep road surface illuminance constant during imaging. Characterized by <1> Or <8> 10. The liquid application device according to claim 9, wherein <10> The imaging device is provided with an automatic air blower that blows air toward the optical system of the imaging device during imaging. Characterized by <1> Or <9> 10. The liquid application device according to claim 9, wherein <11> The imaging device is provided with an automatic air blower that blows air toward the road surface during imaging. Characterized by <1> Or <10> 10. The liquid application device according to claim 9, wherein <12> A liquid application method for a liquid application device that divides a liquid application area into a plurality of divided areas, sequentially moves to each divided area, and applies liquid to a plurality of images in a joined state, an image stitching measurement step in which a reference position set in an area where the ends of the divided areas overlap is placed at a position opposite the end of the divided areas, the reference position set in the area where the ends of the divided areas overlap is read by an imaging device, and the reference position is used as a reference origin for writing an image; A liquid application method characterized by: <13> A computer that controls a liquid application device that sequentially moves to each of a plurality of divided areas obtained by dividing a liquid application area into a plurality of divided areas and applies liquid to a plurality of images in a joined state, A program for functioning as an image connection measurement unit that is positioned opposite the end of the divided area, reads the reference position set in the area where the ends of the divided area overlap with an imaging device, and sets the reference position as the reference origin for image writing. [Explanation of symbols]

[0121] 1 Liquid application device 2 Liquid ejection head 7. Imaging device 7b Automatic dust cover mechanism 7c lighting 7d Automatic air blow 7e Automatic air blower 53 Image stitching measurement section [Prior art documents] [Patent documents]

[0122]

Patent Document 1

Claims

1. A liquid application device that divides a liquid application area into a plurality of areas, sequentially moves to each divided area, and applies liquid to a plurality of images while connecting them together, an imaging device that is disposed at a position facing the end of the divided area and captures an image of a reference position set in an area where the end portions of the divided areas overlap; an image stitching measurement unit that sets a reference position captured by the imaging device as a reference origin for image writing; A liquid application device comprising:

2. the end of the divided region is the end of a head operation range of the liquid ejection head; 2. The liquid application device according to claim 1.

3. an end of the divided region is near the optical axis of the optical system of the imaging device; 2. The liquid application device according to claim 1.

4. The divided regions are rectangular, four of the imaging devices are arranged at the ends of the rectangular divided area; 4. The liquid application device according to claim 1, wherein the liquid application device is a liquid application device.

5. The distance between the imaging devices is set by simultaneously setting the origins of the imaging devices using a reference plate jig indicating the mounting position before operation.

2. The liquid application device according to claim 1.

6. The distance between the imaging devices is set by measuring the joining accuracy of a test joining print using an image before operation and adjusting the origin positions of the imaging devices.

2. The liquid application device according to claim 1.

7. The distance between the imaging devices is set by adjusting the origin positions of the imaging devices using a distance between the two imaging devices that has been measured in advance.

2. The liquid application device according to claim 1.

8. The imaging device is provided with an automatic dust cover mechanism that protects the optical system of the imaging device when not taking pictures.

2. The liquid application device according to claim 1.

9. The imaging device is provided with a light that emits light to keep road surface illuminance constant during imaging.

2. The liquid application device according to claim 1.

10. The imaging device is provided with an automatic air blower that blows air toward the optical system of the imaging device during imaging.

2. The liquid application device according to claim 1.

11. The imaging device is provided with an automatic air blower that blows air toward the road surface during imaging.

2. The liquid application device according to claim 1.

12. A liquid application method for a liquid application device that divides a liquid application area into a plurality of divided areas, sequentially moves to each divided area, and applies liquid to a plurality of images in a joined state, an image stitching measurement step in which a reference position set in an area where the ends of the divided areas overlap is placed at a position opposite the end of the divided areas, the reference position set in the area where the ends of the divided areas overlap is read by an imaging device, and the reference position is used as a reference origin for writing an image; A liquid application method characterized by:

13. A computer that controls a liquid application device that sequentially moves to each of a plurality of divided areas obtained by dividing a liquid application area into a plurality of divided areas and applies liquid to a plurality of images in a joined state, A program for functioning as an image connection measurement unit that is positioned opposite the end of the divided area, reads the reference position set in the area where the ends of the divided area overlap with an imaging device, and sets the reference position as the reference origin for image writing.

Images