JP2005114499A - Inspection device for die coat bead and its inspection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inspection device for a die coat bead and its inspection method for imaging a cross section shape of the bead by high-speed photography and determining the quality and usability of a coating film from an image obtained by imaging a cross section of the bead, in continuous precise coating to a web by a tie head. <P>SOLUTION: This inspection device for a die coat bead is used for observing the cross section shape of a bead 5 in a die coat. The inspection device for a die coat bead comprises a lighting part for lighting by parallel light 25 from one end of a side face of the bead 5, a high-speed camera 32 for imaging the cross section shape of the bead 5 from the other end, an image processing part 41 for processing an image obtained by imaging the cross section shape of the bead 5, and a determination part 51 for determining the cross section shape of the bead 5. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a die coat bead inspection apparatus and method for inspecting a cross-sectional shape of a bead portion in a die coat using a camera and illumination and inspecting the shape of the bead portion.

  Conventionally, the need for coating in the printing field has increased in the direction of improving the coating accuracy of inks, emulsions, and the like. For example, a continuous coating method such as a wet die coating method has been put into practical use.

  The wet die coating method is often used for the purpose of forming a uniform coating film on a continuous film or paper, and is a method in which coating is continuously performed on an object to be coated called a web.

  In the precision coating method as described above, in order to obtain a uniform coating film, if the cross-sectional shape of the bead formed in the minute gap between the web and the die is stable, the resulting coating film is also stable. I know that In general, setting parameters of a coating apparatus and finding coating conditions are often determined based on experience and the completed state of coating. For example, when there is a reaction such as mixing or compounding of the coating liquid, the viscosity of the coating liquid such as ink or emulsion changes depending on its chemical characteristics. Further, in order to improve the flatness of the coating film, viscosity adjustment such as increasing the initial fluidity immediately after coating is performed. In such a case, it is a general method to perform coating while setting parameters such as coating speed and drying conditions, and adjusting the coating conditions while checking the completion of the coating.

  As an apparatus for inspecting the cross-sectional shape of the bead part in the die coat, there is an inspection apparatus that illuminates the bead part obliquely and takes an image by the illumination (see, for example, Patent Document 1).

The above prior art documents are shown below.
JP 2003-247949 A

  However, in the above-described inspection apparatus, checking the cross-sectional shape of the bead portion has a problem that the distance between the die and the web is very fine and cannot be observed by a normal method.

  Moreover, when carrying out precision coating continuously on a web, the conveyance speed of a web will be about 1 m / sec from a slow thing, about 10 m / sec at a fast thing, and the size of a bead part is about 1 mm or less, and it is normal. At an imaging speed of about 30 frames / second, such as a camera, even if the shape of the bead portion is imaged and observed, the shape of the bead changes faster and it is not known whether the bead shape is stable. There is.

  In addition, there is a problem that a space for observing the bead portion is not provided in the coating apparatus.

In this way, when precision coating is performed continuously on the web, it is possible to judge whether the coating is good or not only in the completed state of the coating film, and what state the bead part shape is. There is a problem that it is not known whether the quality of the film can be judged or not.

  The present invention solves the problems of the prior art, and the problem is that, in continuous precision coating on the web by a die head, the cross-sectional shape of the bead is captured with a high-speed photograph, and the bead An object of the present invention is to provide a die coat bead inspection apparatus capable of determining whether a coating film is good or bad from a cross-sectional image, and a die coat bead inspection method using the same.

  In order to achieve the above object in the present invention, in the invention of claim 1, a die coat bead inspection device for inspecting a cross-sectional shape of a bead portion in a die coat, from one end of a side surface of the bead portion. An illumination unit that illuminates, a camera unit that captures the cross-sectional shape of the bead unit from the other end, an image processing unit that processes a captured image of the cross-sectional shape of the bead unit, and the quality of the cross-sectional shape of the bead unit are determined. This is a die coat bead inspection device characterized by comprising a determination unit.

  According to a second aspect of the present invention, there is provided the die coat bead inspection device according to the first aspect, wherein the illumination section outputs parallel light.

  According to a third aspect of the present invention, there is provided the die coat bead inspection apparatus according to the first or second aspect, wherein the camera section has a parallel optical lens system and has a high-speed photographing means. Is.

  According to a fourth aspect of the present invention, the image processing unit obtains a brightness center value and a variance value for each pixel at the same position over a plurality of frames within a certain period of time, and each of the center value image and the variance is obtained. 4. The die coat bead inspection apparatus according to claim 1, further comprising preframe image processing means for generating a value image.

  According to a fifth aspect of the present invention, the determination unit compares the center value determination means for comparing the center value image with a reference center value image prepared in advance, and compares the dispersion value image with a reference dispersion value image prepared in advance. 5. The die coat bead inspection device according to claim 1, further comprising a dispersion value determination unit for determining.

  Furthermore, the invention of claim 6 is a die coat bead inspection method for observing the cross-sectional shape of the bead portion in the die coat, wherein illumination is performed from one end of the side surface of the bead portion, and the cross section of the bead portion from the other end. The die coat bead inspection method is characterized in that the shape is imaged and the quality of the cross-sectional shape of the bead portion is determined based on a captured image of the cross-sectional shape of the bead portion.

  Since this invention is the above structure, there exist the following effects.

That is, according to the present invention, the illumination part of the parallel light illumination that illuminates from one end in the transverse direction of the bead part so as to see the sectional shape of the bead part in the die coat, and the sectional shape of the bead from the other end are imaged. A parallel optical lens and a camera unit having high-speed imaging means, an image processing unit that processes a captured image of the cross-sectional shape of the bead unit, and a determination unit that determines the quality of the cross-sectional shape of the bead unit, The image processing unit obtains a central value and a variance value of brightness for each pixel at the same position over a plurality of frames within a certain period of time, and generates a central value image and a variance value image respectively. And the determination unit includes a center value determination unit for comparing and determining a center value image and a reference center value image prepared in advance, and a dispersion value for comparing and determining a dispersion value image and a reference dispersion value image prepared in advance. By providing a die coat bead inspection device including a fixing means, even if the distance between the die and the web is fine, the bead shape can be stabilized more quickly even if the coating device does not have a space for inspecting the bead portion. Can be inspected.

  Therefore, the present invention exhibits an excellent practical effect as an apparatus and an inspection method for inspecting the shape of a die coat bead in the field of coating ink on a web with a die head.

  The best mode for carrying out the present invention will be described below in detail with reference to the drawings.

  The die coat bead inspection apparatus of the present invention is, for example, a die head (1) for applying ink to a continuously conveyed web (3), as shown in the schematic view shown in the side cross section of FIG. The backup roll (2) to be installed is set to have a gap of 1 mm or less in the case of precise coating, and the web (3) is conveyed in the rotation direction (P) of the backup roll (2). It has become.

  Further, the ink protrudes from the long and narrow slit (1a) of the die head (1) and has a shape like a bead (5). When this bead (5) is in a stable state, the shapes of the upstream leading bead (5a) and the downstream trailing bead (5b) are stable, and the shape thereof hardly changes over time. The coating film (4) has a constant thickness.

  As shown in the front view of FIG. 2, the entire configuration of the die coat bead inspection device of the present invention is such that the web (3) is wound around the backup roll (2) and the rotation direction (P ), The ink is protruded from the slit of the die head (1), the bead (5) is formed, and coating is performed so that the coating film (4) is stabilized. In the present invention, illumination is performed from the right end of the die head (1) so as to transmit the entire bead (5), and parallel light (25) is irradiated to image the cross section of the bead (5). The parallel light (25) has a plurality of light sources incident on the integrating sphere (21) so as to prevent the effective use of light flux and light and darkness due to light interference, and a pinhole (22) opened in the integrating sphere. A collimating lens (24) is used as a point light source for collimation. In the case of the present invention, for example, a plurality of metahalide light sources (11a) and light beams from the metahalide light sources (11b) are incident on the integrating sphere (21) by the light guide (12a) and the light guide (12b). A shielding plate (13a) and a shielding plate (13b) are provided so that the incident light (14a) and the incident light (14b) to the integrating sphere (21) do not directly enter the pinhole (22). Further, the integrating sphere (21) is made of stainless steel, and can be accommodated in a limited space on the practical machine of the coater by being downsized to about 10 cm in diameter. Further, as the integrating sphere (21), a press-formed product of stainless steel having a thickness of about 3 mm and a half sphere was used.

  In the case of this example, the pinhole (22) can obtain desired brightness and parallel light at about 0.5 mm to 1.2 mm. As the collimator lens (24), parallel light (25) can be easily obtained by using an objective lens of a microscope, and the entire bead (5) is transmitted through the silhouette transmitted light (26) of the bead (5). Is imaged with a telecentric lens (31) and a high-speed camera (32).

At this time, the telecentric lens (31) is used to take an image of the bead (5) located at the back of the end face of the die head (1) and the backup roll (2). The high-speed camera (32) uses a high-speed camera of about 1000 frames / second to 8000 frames / second based on the conveyance speed, the size of the bead (5), and the speed of shape change. By extracting the characteristics of the shape of the bead (5) and comparing the stable shape of the bead (5) as a basic value, it becomes possible to inspect the state of the coating film.

  In the present example, the image processing unit (41) calculates, for example, the center value and the variance value for each pixel of the captured images of a plurality of frames, and sets the center value image and the variance value image, respectively. The determination unit (51) that compares the dispersion value image with the reference center value image and the reference dispersion value image determines whether the bead (5) is good or bad. The reference center value image and the reference dispersion value image can be created by selecting and storing the bead (5) in a stable state in the reference image portion (61).

  The shape of the bead (5) in the general application is, for example, as shown in the schematic diagram represented by the side cross section of FIG. 3 (A), for example, the ink protrudes from the long and narrow slit of the die head (1). It becomes a shape like this. The bead (5) has an upstream leading bead (5a) and a downstream trailing bead (5b). In the case of stable application, the bead (5) has a constant thickness applied to the continuously conveyed web (3). It becomes a film (4).

  In FIG. 3B, the shape of the bead (5) is thicker as indicated by the broken line, moves to the upstream side to become a leading bead (5a1), and similarly the trailing bead (5b1) also has a thicker downstream side. 3C shows that the bead (5) has a thin shape as indicated by the broken line, moves downstream, and becomes a leading bead (5a2). It shows a state that it becomes like a thin trailing bead (5b2) and the coating film is also thinned.

  As shown in FIG. 4A, the state of the coating film (4) due to the thickening and thinning of the bead (5) is such that the entire bead (5) is periodically thickened or thinned in the entire slit width direction. When it repeats, a mode that the horizontal stripe unevenness (4a) generate | occur | produces in the coating film (4) is shown.

  Further, as shown in FIG. 4 (B), the state of the coating film (4) due to the thickening and thinning of some of the beads is such that the vertical smoothing line (4) in the coating film (4) in the conveying direction (Q) of the web (3). 4b) is shown.

  As described above, it is possible to know from the observation of the present invention that the coating film (4) changes due to the change in the cross-sectional shape of the bead (5).

  FIG. 5A schematically shows the imaging range (100) imaged by the high-speed camera (32), which is located near the lower end of the die head (1), the upper surface of the backup roll (2), and the web (3). Take an image as follows.

  FIG. 5B schematically shows the silhouette transmitted light (26). In the imaging range, the lower end of the die head (1) and the web (3) near the upper surface of the backup roll (2) are silhouettes. It is a silhouette image (101) showing a state of being displayed as (shadow) and black (dark). Ink is projected into the gap between the lower end of the die head (1) and the web (3) to form a bead (5).

  FIG. 6 schematically shows the arrangement of pixels when image processing is performed on the silhouette image (101). The upper left pixel is (1.1) the upper right pixel is (200.1), and the lower left pixel is (1.60), the lower right pixel is (200.60), the horizontal direction is 200 pixels, and the vertical direction is 60 pixels. The high-speed camera of this embodiment has a configuration of 200 pixels in the horizontal direction and 60 pixels in the vertical direction when the imaging speed is 5000 frames / second or more.

  FIG. 7A shows silhouette images captured at 5000 frames / second for six frames from a) to f) sequentially, and shows an image in which the shape of the bead (5) is stable. . Further, a) of FIG. 7B shows the central value (average value) of the brightness of the pixels at the same position in the four images of a), b), c), and d) of FIG. It is a result of calculation processing and imaging. Further, b) in FIG. 7B calculates the central value (average value) of the brightness of the pixels at the same position in the four images of b), c), d), and e) in FIG. Processed and imaged. Further, c) in FIG. 7B shows the central value (average value) of the brightness of the pixels at the same position in the four images of c), d), e), and f) in FIG. It is a result of calculation processing and imaging.

  Furthermore, a) in FIG. 7C calculates the variance value of the brightness of the pixels at the same position in the four images in FIG. 7A a), b), c) and d). It is an image. Further, b) in FIG. 7C calculates the variance value of the brightness of the pixels at the same position in the four images b), c), d), and e) in FIG. It has become. C) in FIG. 7C is obtained by calculating the brightness variance values of the pixels at the same position in the four images of c), d), e), and f) in FIG. Is.

  The center value image in FIG. 7B is similar because the bead (5) is stable. In addition, since the variance value image in FIG. 7C has little change in brightness, the lower end of the die head (1), the upper surface of the backup roll (2), and the web (3) are bright as shown by the broken lines. Further, since the bead (5) is stable, the change is similarly reduced and the bead portion becomes a bright image. If the variance value image has a change in brightness, it will be a bright image, and if the change in brightness is large, only the changed part will be displayed dark so that there is no change in the center value image. However, you can see that the bead part has changed.

  Also, captured images when the bead portion changes are shown from a) to h) in FIG. The center value images for each of these four frames are shown from a) to f) in FIG. The dispersion value images for every four frames are shown from a) to f) in FIG.

  FIG. 9A shows a reference center value image when a center value image and a variance value image of a captured image when the bead state is stable are stored and used as a reference image for determination processing. . Similarly, the reference dispersion value image is shown in FIG.

  FIG. 8A shows the captured image, a) (bead thickness = middle), b) (bead thickness = thick), c) (bead thickness = middle), d) (bead thickness = thin). The center value image of 4 frames is a) (bead thickness = medium) in FIG. 8B, and the variance value image is a) in FIG. 8C.

  Further, when compared with FIG. 9A showing the reference center value image (referred to as bead thickness = medium), the determination result is “= (equal, same)” as shown in FIG. Judgment is made. Next, the dispersion value image is compared with “= thin” as shown in FIG. 8C and a dispersion value reference dispersion value image FIG. ) Is determined as “≠ (not equal, not the same)” as in a).

  In this way, b) to f) in FIG. 8 (B) showing the center value image and b) to b) in FIG. 8 (B) showing the dispersion value image are sequentially obtained, and FIG. 9 showing the reference center value image. (A) Compared with FIG. 9B showing the dispersion value reference dispersion value image, the center value determination result, from b) to f) in FIG. 10A, and the dispersion value determination result in FIG. 10B. From b) to f) can be obtained.

It is explanatory drawing which represented the outline | summary of the die-coat bead shape of this invention with the sectional side view. It is explanatory drawing which represented typically one Example of the die coat bead inspection apparatus of this invention. It is explanatory drawing which represented the change outline | summary of the die-coat bead shape of this invention with the sectional side view. (A) is explanatory drawing which represented the horizontal stripe unevenness of the general die coat typically, (B) is explanatory drawing which represented the vertical stripe unevenness of the general die coat typically. (A) is explanatory drawing which represented the imaging range shape of the die-coat bead part of this invention with the sectional side view, (B) is explanatory drawing which represented the captured image of the die-coated bead part of this invention with the sectional side view It is. It is explanatory drawing which represented typically one Example of the image processing range of the captured image of the die coat bead inspection apparatus of this invention. (A) is explanatory drawing which represented typically the picked-up image for several frames when the bead shape of the die coat bead inspection apparatus of this invention is stable, (B) is the die coat bead inspection of this invention It is explanatory drawing which represented typically one Example of the center value image processing of an apparatus, (C) is explanatory drawing which represented typically one Example of the dispersion value image processing of the die coat bead inspection apparatus of this invention It is. (A) is explanatory drawing which represented typically the picked-up image for several frames when the bead shape of the die coat bead inspection apparatus of this invention is not stable, (B) is the die coat bead inspection of this invention It is explanatory drawing which represented typically one Example of the center value image processing of an apparatus, (C) is explanatory drawing which represented typically one Example of the dispersion value image processing of the die coat bead inspection apparatus of this invention It is. (A) is explanatory drawing which represented typically one Example of the reference | standard center value image of the die coat bead inspection apparatus of this invention, (B) is a reference | standard dispersion | distribution value image of the die coat bead inspection apparatus of this invention. It is explanatory drawing which represented one Example typically. (A) is explanatory drawing which represented the die coat bead shape center value determination processing result of this invention typically, (B) is the die coat bead shape dispersion value judgment processing result of this invention typically represented. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Die head 1a ... Slit 2 ... Backup roll 3 ... Web 4 ... Paint film 4a ... Horizontal stripe uneven coat 4b ... Vertical stripe stripe coat 5 ... Bead 5a, 5a1, 5a2 Reading Beads 5b, 5b1, 5b2 ... Trailing beads 10 ... Visual direction arrows 11a and 11b ... Metahalide light sources 12a and 12b ... Light guides 13a and 13b ... Shield plates 14a and 14b ... Incident light 22 ... Pinholes 23 ... Point light source 24 ... Collimator lens 25 ... Parallel light 26 ... Silhouette transmitted light 31 ... Telecentric lens 32 ... High-speed camera 41 ... Image processing part 51 ... Judgment part 61 ... Standard image part 100 Imaging range 101 Silhouette image 51 Trigger

Claims (6)

  A die coat bead inspection device for inspecting a cross-sectional shape of a bead part in a die coat, an illumination part that illuminates from one end of a side surface of the bead part, and a camera part that images a cross-sectional shape of the bead part from the other end A die coat bead inspection apparatus comprising: an image processing unit that processes a captured image of a cross-sectional shape of the bead portion; and a determination unit that determines whether the cross-sectional shape of the bead portion is good or bad.   2. The die coat bead inspection device according to claim 1, wherein the illumination unit outputs parallel light.   3. The die coat bead inspection apparatus according to claim 1, wherein the camera unit has a parallel optical lens system and high-speed photographing means.   The image processing unit obtains a center value and a variance value of brightness for each pixel at the same position over a plurality of frames within a certain period of time, and generates a center value image and a variance value image respectively. 4. The die coat bead inspection device according to claim 1, further comprising means.   The determination unit includes a center value determination unit that compares and determines a center value image and a reference center value image prepared in advance, and a dispersion value determination unit that compares and determines a dispersion value image and a reference dispersion value image prepared in advance. The die coat bead inspection device according to any one of claims 1 to 4.   A die coating bead inspection method for observing a cross-sectional shape of a bead portion in a die coat, wherein illumination is performed from one end of a side surface of the bead portion, a cross-sectional shape of the bead portion is imaged from the other end, and a cross-section of the bead portion A method of inspecting a die coat bead, wherein the quality of a cross-sectional shape of the bead portion is determined based on a captured image of the shape.