JP7513969B2 - Coating film edge evaluation method and coating film edge evaluation device - Google Patents

Description

Article 30, paragraph 2 of the Patent Act applies. (1) Proceedings of the 2019 Sasebo Regional Lecture and the 20th Student Research Presentation Session, co-hosted by the Kyushu Branch and Chugoku-Shikoku Branch of the Japan Society for Precision Engineering, p. 190, published on December 14, 2019. (2) The 20th Student Research Presentation Session, co-hosted by the Kyushu Branch and Chugoku-Shikoku Branch of the Japan Society for Precision Engineering, held on December 14, 2019. (3) Proceedings of the 51st Student Member Graduation Research Presentation Session, Kyushu Student Association, Kyushu Branch of the Japan Society of Mechanical Engineers, published on March 6, 2020.

The technology disclosed in this specification relates to a coating film end evaluation method and coating film end evaluation device.

The technology of applying a coating liquid to a substrate to form a coating film is used in a variety of fields. Conventionally, the quality of the formed coating film has generally been evaluated by visual sensory evaluation by multiple evaluators. However, this type of sensory evaluation lacks objectivity and universality due to variations in evaluation criteria and judgments among evaluators.

To solve these problems, a technology has been proposed that uses an imaging device to capture an image of the light reflected from the coating being evaluated, divides the image into multiple regions, calculates the brightness of each region, and evaluates the unevenness of the paint based on the brightness difference between adjacent regions (see Patent Document 1).

JP 2012-7953 A

When forming a coating film, generally, the parts of the substrate surface where the coating liquid must not adhere are covered with a masking material, and then the coating liquid is applied. This requires a process in which the masking material is attached to the substrate before coating and then peeled off after coating, which is time-consuming and costly. To reduce this time and cost, there is a demand for coating that can be performed without masking. To achieve this, it is necessary to develop a film-forming method that results in clearly linear edges of the formed coating film, and it is important to objectively evaluate the condition of the coating film edges. However, the technology for such evaluation has not yet been established.

The coating film edge evaluation method disclosed in this specification is a method for evaluating the state of the edge of a coating film formed by applying a coating liquid to a substrate, and includes an image acquisition step of acquiring an image of the coating film, a profile generation step of processing the image acquired by the image acquisition step to generate a line profile representing the distribution of brightness along a line in a direction perpendicular to the coating film formation direction, and a region determination step of determining, based on the line profile, a coating region where the coating film is formed, a non-coating region where the coating film is not formed, and a boundary region between the coating region and the non-coating region.

The coating film edge evaluation device disclosed in this specification is a device for evaluating the state of the edge of a coating film formed by applying a coating liquid to a substrate, and includes an image acquisition unit that acquires an image of the coating film, a profile generation unit that processes the image acquired by the image acquisition unit to generate a line profile that represents the distribution of brightness along a line in a direction perpendicular to the coating film formation direction, and a region determination unit that determines, based on the line profile, a coating region where the coating film is formed, a non-coating region where the coating film is not formed, and a boundary region between the coating region and the non-coating region.

The above configuration makes it possible to quantify (quantify) the condition of the edge of the coating film, such as the width of the boundary area and offset, and to objectively evaluate the condition of the edge of the coating film.

The coating film end evaluation method and coating film end evaluation device disclosed in this specification make it possible to quantify (quantify) the condition of the coating film end, and to objectively evaluate the condition of the coating film end.

FIG. 1 is a block diagram showing a configuration of an evaluation device according to an embodiment. FIG. 2 is a schematic side view of the coating device according to the embodiment. FIG. 3 is a flowchart illustrating an operation mode of the evaluation device in the embodiment. FIG. 4 is a microscope image of a coating according to an embodiment. FIG. 5 is a graph showing an averaged line profile in an embodiment. FIG. 6 is a graph showing the deposition, non-deposition, and boundary regions determined for an averaged line profile.

[Overview of the embodiment]
The method for evaluating the ends of a coating film disclosed in this specification is a method for evaluating the condition of the ends of a coating film formed by applying a coating liquid to a substrate, and includes an image acquisition step of acquiring an image of the coating film, a profile generation step of processing the image acquired by the image acquisition step to generate a line profile representing the distribution of brightness along a line in a direction perpendicular to the film formation direction of the coating film, and a region determination step of determining, based on the line profile, a film-formed region where the coating film is formed, a non-film-formed region where the coating film is not formed, and a boundary region between the film-formed region and the non-film-formed region.

The coating film edge evaluation device disclosed in this specification is a device for evaluating the state of the edge of a coating film formed by applying a coating liquid to a substrate, and includes an image acquisition unit that acquires an image of the coating film, a profile generation unit that processes the image acquired by the image acquisition unit to generate a line profile that represents the distribution of brightness along a line in a direction perpendicular to the coating film formation direction, and a region determination unit that determines, based on the line profile, a coating region where the coating film is formed, a non-coating region where the coating film is not formed, and a boundary region between the coating region and the non-coating region.

The above configuration makes it possible to quantify (quantify) the condition of the edge of the coating film, such as the width of the boundary area and offset, and to objectively evaluate the condition of the edge of the coating film.

In the above configuration, the coating film may be formed by a spray method.

When forming a coating film by the spray method, the coating liquid tends to splash and form a relatively wide boundary area between the coating area and the non-coating area where the coating liquid is unevenly applied. In such cases, it is preferable to quantitatively evaluate the edge of the coating film using the above-mentioned evaluation method and evaluation device.

<Embodiment>
The embodiment will be described with reference to FIGS.

(Overall configuration of coating film end evaluation device 10)
The coating edge evaluation device 10 (hereinafter abbreviated as "evaluation device 10") of this embodiment is a confocal laser scanning microscope, and as shown in Fig. 1, has a general configuration including a light source device 11 that emits laser light, an illumination optical system 12 that irradiates a sample with the laser light emitted from the light source device 11, a detection optical system 13 that detects reflected light from the sample, and a processing device 14 that processes a signal acquired by the detection optical system 13. The illumination optical system 12 includes a two-axis galvano scanner (hereinafter abbreviated as "scanner") that two-dimensionally scans the laser light emitted from the light source device 11.

The processing device 14 is, for example, a personal computer, and includes a control unit 15 and a calculation unit 16. The control unit 15 controls the operations of the light source device 11, the illumination optical system 12, and the detection optical system 13. The calculation unit 16 includes an image acquisition unit 17, a profile generation unit 18, and an area determination unit 19. The image acquisition unit 17 generates a two-dimensional image by storing the scanning position of the laser light sent from the scanner and the signal sent from the detection optical system 13 when the reflected light from the scanning position is detected in association with each other. The profile generation unit 18 generates a line profile for the line L set on the obtained image. The area determination unit 19 determines the film formation area 22 where the coating film 21 is formed, the non-film formation area 23 where the coating film 21 is not formed, and the boundary area 24 between the film formation area 22 and the non-film formation area 23 based on the generated line profile.

(Film forming method)
Next, a method for forming the coating film 21 to be evaluated will be described. The coating device 30 used for the film formation is a device for forming the coating film 21 on the surface of the substrate 20 by electrostatic coating, and includes a spray nozzle 32 and a stage 33 installed inside a film formation chamber 31, and a liquid supply unit 35 and a voltage application unit 38 connected to the spray nozzle 32, as shown in FIG.

The stage 33 is a metal platform that is installed horizontally inside the film formation chamber 31. An earth wire 34 is connected to the stage 33, and the stage 33 is grounded by this earth wire 34.

The spray nozzle 32 is a nozzle used to spray the coating liquid 39 by electrostatic coating, and is installed inside the film formation chamber 31 with its spray outlet facing the stage 33. In this embodiment, an electrostatic atomizing nozzle is used as the spray nozzle 32. The spray nozzle 32 is adapted to be scanned in the horizontal direction by a driving device. The spray nozzle 32 is equipped with an internal electrode inside.

The liquid supply unit 35 includes a storage container 36 in which the coating liquid 39 is stored, and a liquid delivery pipe 37 that connects the storage container 36 to the spray nozzle 32. The coating liquid 39 stored in the liquid supply unit 35 is delivered to the spray nozzle 32 at a set flow rate by a pump.

The voltage application unit 38 is a device that applies a predetermined voltage to the internal electrode of the spray nozzle 32. The coating liquid 39 sent to the spray nozzle 32 is charged and atomized by applying a voltage to the internal electrode, and is sprayed from the tip of the spray nozzle 32.

Next, we will explain the procedure for forming a coating film 21 on a substrate 20 using the coating device 30.

First, the substrate 20 is set on the stage 33. Next, the spray nozzle 32 is scanned in a predetermined film-forming direction (Y-axis direction: the direction of the arrow in Figures 2 and 4), and the coating liquid 39 is sprayed onto the substrate 20. After spraying, the substrate 20 is subjected to processes such as drying and curing as necessary. In this way, a sample is obtained in which a coating film 21 is formed on the surface of the substrate 20. It is preferable that the combination of the substrate 20 and the coating liquid 39 is selected so that the contrast between the coating film 21 that is formed and the portion of the substrate 20 where the coating film 21 is not formed is sufficiently large.

(Operational aspects of evaluation device 10)
The process of evaluating the coating film 21 formed by the coating apparatus 30 using the evaluation apparatus 10 will be described with reference to Figs. 3 to 6.

First, the control unit 15 of the processing device 14 controls the light source device 11 and the illumination optical system 12 to irradiate the sample with laser light while performing a two-dimensional scan. The light reflected from the sample is detected by the detection optical system 13 and sent to the image acquisition unit 17. The image acquisition unit 17 generates a two-dimensional image by storing the scanning position of the laser light sent from the scanner of the illumination optical system 12 and the signal sent from the detection optical system 13 when the reflected light from that scanning position is detected in association with each other (step S1: image acquisition process).

Next, the profile generating unit 18 sets a linear line L extending in a direction perpendicular to the deposition direction on the obtained image, and generates a line profile of the luminance value for this line L (step S2: profile generating process). Here, the line profile is a graph showing the change in the luminance value (output value from the detection optical system 13) of the pixels arranged on the line L, with the horizontal axis representing the position of each pixel in the direction perpendicular to the deposition direction (position in the X-axis direction in FIG. 4) and the vertical axis representing the luminance. In this embodiment, a line profile is generated for each of the multiple lines L1, L2...Ln, and an averaged line profile is obtained by averaging these multiple line profiles. More specifically, the average value of the luminance value of pixels whose positions in the X-axis direction (X coordinate value) match for the multiple line profiles is obtained, and an averaged line profile (see FIG. 5) is drawn. This makes it possible to reduce the influence of noise. In this specification, when multiple lines are to be distinguished from each other, suffixes 1, 2, 3...n are added to the symbols of the lines, and when they are referred to collectively without distinction, suffixes are not added to the symbols.

Next, the film-formed region 22, the non-film-formed region 23, and the boundary region 24 are determined for the averaged line profile according to the preset conditions (step S3: region determination process). The film-formed region 22 is a region in which the coating film 21 is formed to a degree that is acceptable in terms of film-formed quality. The non-film-formed region 23 is a region in which little or no coating liquid 39 adheres to the substrate 20, and the coating film 21 is not formed. The boundary region 24 is a region in which the coating liquid 39 adheres unevenly, and the coating film 21 is not formed to a degree that is acceptable in terms of film-formed quality, and exists between the film-formed region 22 and the non-film-formed region 23. In this embodiment, when the maximum brightness value is set to 100% and the minimum brightness value is set to 0% in the averaged line profile, an example is shown in which the region of 10% or less is the film-formed region 22, the region of 90% or more is the non-film-formed region 23, and the intermediate region between the two is the boundary region 24 (see FIG. 6). This allows the state of the coating edge, such as the width and offset of the boundary region 24, to be quantified (quantified) and objectively evaluated. For example, if the width of the boundary region 24 is narrow and the difference in the width of the boundary region 24 on both sides of the coating region 22 is small, it can be determined that the coating has been formed better. In addition, by comparing the width and offset of the boundary region for multiple coatings formed under different coating conditions, it is possible to determine the better coating conditions.

(Action and Effect)
As described above, the method for evaluating the ends of a coating film in this embodiment is a method for evaluating the condition of the ends of a coating film 21 formed by applying a coating liquid 39 to a substrate 20, and includes an image acquisition step of acquiring an image of the coating film 21, a profile generation step of processing the image acquired by the image acquisition step to generate a line profile representing the distribution of brightness along a line L in a direction perpendicular to the film formation direction of the coating film 21, and a region determination step of determining, based on the line profile, a film formation region 22 where the coating film 21 is formed, a non-film formation region 23 where the coating film 21 is not formed, and a boundary region 24 between the film formation region 22 and the non-film formation region 23.

The coating film end evaluation device 10 of this embodiment is a device for evaluating the state of the end of the coating film 21 formed by applying the coating liquid 39 onto the substrate 20, and includes an image acquisition unit 17 for acquiring an image of the coating film 21, a profile generation unit 18 for processing the image acquired by the image acquisition unit 17 to generate a line profile representing the distribution of brightness along a line L in a direction perpendicular to the deposition direction of the coating film 21, and an area determination unit 19 for determining the coating region 22 where the coating film 21 is formed, the non-coating region 23 where the coating film 21 is not formed, and the boundary region 24 between the coating region 22 and the non-coating region 23 based on the line profile.

The above configuration makes it possible to quantify (quantify) the condition of the edge of the coating film 21, such as the width and offset of the boundary region 24, and to objectively evaluate the condition of the edge of the coating film 21.

The coating film 21 is formed by a spray method. When the coating film 21 is formed by a spray method, the coating liquid 39 tends to splash and form a relatively wide boundary region 24 between the coating region 22 and the non-coating region 23 where the coating liquid 39 is unevenly applied. In such a case, it is preferable to quantitatively evaluate the edge of the coating film 21 using the above-mentioned evaluation method and evaluation device 10.

<Other embodiments>
The technology disclosed in this specification is not limited to the embodiments described above and illustrated in the drawings, and also includes various aspects such as the following.
(1) In the above embodiment, a confocal laser scanning microscope is used as the evaluation device 10. However, devices other than a confocal laser scanning microscope may also be used as the evaluation device.
(2) In the above embodiment, the coating film 21 formed by electrostatic painting is evaluated. However, a coating film formed by a film forming method other than electrostatic painting may also be evaluated.
(3) The method of averaging the line profile is not limited to the method described in the above embodiment, and any known method can be applied. Furthermore, the deposition region, non-deposition region, and boundary region may be determined using a line profile that has not been averaged.

10... Coating film end evaluation device 15... Image acquisition unit 16... Profile generation unit 17... Region determination unit 20... Substrate 21... Coating film 22... Coating region 23... Non-coating region 24... Boundary region 39... Coating liquid L... Line

Claims (3)

A method for evaluating the condition of the edge of a coating film formed by applying a coating liquid onto a substrate, comprising the steps of:
an image acquisition step of acquiring an image of the coating film;
a profile generating step of processing the image obtained by the image acquiring step to generate a line profile representing a distribution of luminance along a line in a direction perpendicular to the film forming direction of the coating film;
and a region determining step of determining, based on the line profile, a film-formed region where the coating film is formed, a non-film-formed region where the coating film is not formed, and a boundary region between the film-formed region and the non-film-formed region ,
In the profile generation step,
The line profile is represented by a graph in which the horizontal axis represents the position of each pixel in the direction perpendicular to the film formation direction and the vertical axis represents the luminance value of each pixel for each pixel arranged on a line in a direction perpendicular to the film formation direction of the coating film, and a plurality of the lines are obtained in the film formation direction, the line profile is generated for each of the plurality of lines, and an average value of the luminance values of pixels that are positioned in the same direction in the perpendicular direction in the plurality of the line profiles is calculated to generate an averaged line profile;
In the region determining step,
In the averaged line profile, a region where the brightness value is equal to or less than a predetermined value is determined as the film-formed region, a region where the brightness value is equal to or more than the predetermined value is determined as the non-film-formed region, and an intermediate region between the two is determined as the boundary region;
A method for evaluating an edge of a coating film, comprising: evaluating a condition of the edge of the coating film based on a difference between a width of the boundary region and a width of the boundary region on both sides of the coating region .
In the region determining step,
2. The method for evaluating the end of a coating film according to claim 1, wherein, in the averaged line profile, when the maximum brightness value is 100% and the minimum brightness value is 0%, a region where the brightness value is 10% or less is determined as the film-formed region, a region where the brightness value is 90% or more is determined as the non-film-formed region, and an intermediate region between the two is determined as the boundary region.
A coating film edge evaluation device for evaluating the state of an edge of a coating film formed by applying a coating liquid onto a substrate, comprising:
an image acquisition unit for acquiring an image of the coating film;
a profile generating unit that processes the image obtained by the image acquiring unit to generate a line profile that represents a distribution of luminance along a line in a direction perpendicular to a deposition direction of the coating film;
a region determining unit that determines a film-formed region where the coating film is formed, a non-film-formed region where the coating film is not formed, and a boundary region between the film-formed region and the non-film-formed region based on the line profile ,
In the profile generation unit,
The line profile is represented by a graph in which the change in luminance value of pixels lined up on the line is plotted on the horizontal axis representing the position of each pixel in a direction perpendicular to the film formation direction and on the vertical axis representing luminance, and a plurality of the lines are lined up in the film formation direction, and the line profile is generated for each of the plurality of lines, and an average value of the luminance values of pixels in the plurality of line profiles that are positioned in the perpendicular direction is calculated to generate an averaged line profile,
In the region determination unit,
In the averaged line profile, when the maximum brightness value is 100% and the minimum brightness value is 0%, a region where the brightness value is 10% or less is determined as the film-formed region, a region where the brightness value is 90% or more is determined as the non-film-formed region, and an intermediate region between the two is determined as the boundary region;
A coating edge evaluation device that evaluates the condition of the coating edge based on a difference between a width of the boundary region and the widths of the boundary regions on both sides of the coating region .

Images