JP2016200439A - Coating film unevenness measurement method and coating film unevenness measurement device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image measurement method capable of performing the inspection of coating unevenness generated due to delicate drying conditions perceivable at last by human eyes which has been difficult in the past and an image measurement device.SOLUTION: A coating film inspection device includes: a transparent substrate 4 having a periodic electrode pattern 3 formed on the surface; an electric power supply 13 for applying a voltage to the electrode pattern; a light source 1 for irradiating light on a coating film 5 coated on the transparent substrate; and an image detector 12 provided with a collimate lens 2 using light from the light source as substantially parallel light and detecting an image of diffraction light generated from the coating film by light irradiation. The coating film is coated on the transparent substrate 4 formed with the periodic electrode pattern on the surface, and the voltage is applied to the electrode pattern 3, and zeroth order diffraction light close to the diffraction angle in which light intensity of a first side lobe becomes zero is detected from among the diffraction light generated when light is irradiated on the coating film 5.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method and an apparatus for measuring coating film unevenness that occur in a coating film during a drying process of a coating film in which a coating material such as ink or a polymer resin solution is applied to a substrate.

  In the process of forming a coating film with a paint such as an ink or a polymer resin solution such as an optical film, a gas barrier film, or a liquid crystal-related color filter, the product may be defective due to uneven appearance. Optical films and color filters cause defects in optical characteristics, and gas barrier films cause poor barrier performance.

  In order to suppress the occurrence of such unevenness, measure at which stage unevenness occurs in each paint and each coating and drying condition, and identify and apply the optimal paint and coating and drying conditions so that unevenness does not occur It is effective. However, the coating film is usually as thin as about 1 μm to several hundred μm, and it is colored or transparent, and the illumination conditions and the angle at which the coating film is visually observed or taken with a camera etc. vary depending on unevenness. Often difficult to observe.

  As a method for inspecting the unevenness of the coating film, a method of measuring the image by emphasizing the unevenness of the coating film by changing the illumination method or the like is often used. In this method, unevenness is picked up by slightly changing the illumination method and angle, but it is difficult to image unevenness due to slight changes in reflected light and transmitted light with high sensitivity (Patent Document 1).

  Further, in the process of applying a coating film in a liquid state and drying, it is difficult to measure with emphasis on unevenness when it is desired to change the paint and drying conditions to obtain a condition that does not cause unevenness. Also, when it is desired to confirm in which drying stage the unevenness occurs, it is difficult to measure the unevenness image because the properties of the coating film change and the optical conditions also differ.

JP-A-10-142101

  The present invention has been made in order to solve the above-mentioned problems, and image measurement capable of inspecting minute coating film unevenness caused by drying conditions, which has been difficult in the past and can be finally detected by the human eye. It is to provide a method and an image measuring device.

  As means for solving the above problems, the invention according to claim 1 is characterized in that a coating film is formed on a transparent substrate having a periodic electrode pattern formed on the surface, and a voltage is applied to the electrode pattern. In this coating film unevenness measuring method, the first side lobe is irradiated with substantially parallel light, and zero-order diffracted light close to the diffraction angle at which the light intensity becomes zero is detected.

  The invention according to claim 2 is characterized in that diffracted light is image-detected at a diffraction angle at which the diffracted light intensity is lower than the peak intensity in the side lobe of the diffracted light. Is the method.

The invention according to claim 3 is the coating film unevenness measuring method according to claim 1 or 2, wherein the light irradiation is performed with substantially parallel light of multiple wavelengths.

The invention according to claim 4 is a transparent substrate having a periodic electrode pattern formed on the surface,
A power source for applying a voltage to the electrode pattern;
An image that includes a light source for irradiating the coated film on the transparent substrate with light and a collimator lens that makes light from the light source substantially parallel light, and detects an image of diffracted light generated from the film by light irradiation. A detector;
A coating film inspection apparatus comprising:
Of the diffracted light generated when the coating film is applied on a transparent substrate having a periodic electrode pattern formed on the surface, a voltage is applied to the electrode pattern, and the coating film is irradiated with light, the first A coating film unevenness measuring apparatus that detects zero-order diffracted light close to a diffraction angle at which the light intensity of a side lobe becomes zero.

  Further, the invention according to claim 5 is characterized in that the diffracted light image is detected at a diffraction angle at which the diffracted light intensity is lower than the peak intensity in the side lobe of the diffracted light. Device.

  The invention according to claim 6 is the coating film unevenness measuring apparatus according to claim 4 or claim 5, wherein the light irradiation is performed with substantially parallel light of multiple wavelengths.

  According to the apparatus of the present invention, unevenness of the coating film during drying can be deformed along a periodic electrode pattern by applying an electric field to the substrate, and the unevenness can be emphasized as a change in diffracted light. It is possible to detect with high sensitivity minute coating unevenness that occurs due to drying conditions that can be finally detected. Moreover, not only unevenness due to the difference in the thickness of the coating film but also the difference in the dry state of the coating film that varies depending on the location can be measured in the process.

It is a section conceptual diagram showing the composition of the coating-film nonuniformity measuring device of the present invention. It is explanatory drawing explaining Embodiment 1 of this invention. It is explanatory drawing explaining Embodiment 2 of this invention. It is explanatory drawing explaining Embodiment 3 of this invention. It is explanatory drawing explaining Embodiment 4 of this invention. It is a conceptual diagram of the pattern of the electrode used for embodiment of this invention.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. FIG. 1 shows the configuration of a coating film unevenness measuring apparatus according to the present invention, a transparent substrate 4 having a periodic electrode pattern 3 formed on the surface, a power supply 13 for applying a voltage to the electrode pattern 3, and a transparent substrate. 4 includes a light source 1 for irradiating the coating film 5 applied on the light 4, a collimating lens 2 that makes light from the light source substantially parallel light, and an image detector 12 that detects an image of diffracted light generated from the coating film 5. As the transparent substrate 4, a quartz glass base material that transmits visible light or the like is used.

  After the coating film 4 on the transparent substrate 4 having the periodic electrode pattern 3 formed on the surface is formed, a voltage is applied to the electrode pattern, and the collimating lens 2 irradiates light that has become substantially parallel light. As the light source 1, halogen light, metal halide light, LED light, xenon light, or the like is used.

The periodic structure 6 of the electrode pattern 3 is an opening that transmits light, and the transparent substrate 4 has a structure that does not transmit light in portions other than the periodic structure 6. In the transparent substrate 4 having the periodic structure 6, when considered in a one-dimensional direction, diffracted light is generated by the relationship between the width 7 of the periodic structure and the interval 8 of the periodic structure. FIG. 6 shows a pattern of the interdigital electrode used in the embodiment of the present invention.

  The distance 10 from the light source 1 to the irradiation position of the coating film 5 and the distance 10 from the light source 1 to the coating film 5 and the vertical line to the irradiation position are obtained by dividing the distance 10 by the distance 9, that is, from the light source 1 to the irradiation position. The direction cosine p is taken. The diffraction angle 11 is obtained by subtracting the inverse cosine of the direction cosine p from 90 degrees.

<Embodiment 1>
FIG. 2 is an explanatory diagram for explaining Embodiment 1 of the present invention. When light of a specific wavelength is irradiated from the light source device 1 with the direction cosine p, the image detector 12 has the periodic structure 6 and the coating film 5 formed thereon. Diffracted light generated by the transmitted light is detected. The relationship between the direction cosine p and the light intensity of the diffracted light detected by the image detector 12 is shown.

  Suppose that the width 7 of the periodic structure is s, the interval 8 of the periodic structure is d, and the number of the periodic structures in the irradiation area is N. The intensity of the diffracted light detected by the image detector 12 is the square of sin (Nx) / sin (x) in which a sharp intensity appears for each period obtained by dividing the wavelength λ by d as shown in FIG. As shown in FIG. 2B, the characteristic term 16 is expressed by the product of the squared characteristic term 17 of sinc (x) in which the intensity becomes zero for each period obtained by dividing the wavelength λ by s.

  That is, the light intensity 18 detected by the image detector 12 shows a sharp light intensity with a period of λ / d at a certain wavelength λ with respect to the direction cosine p as shown in FIG. It increases / decreases by the square of the sinc function that becomes zero in the period of.

  Here, if the interval 8 of the periodic structure is relatively large, in the light intensity 18, diffraction of each order generated at an interval of λ / d approaches the direction cosine p. Therefore, it becomes difficult for the image detector 12 to detect only the diffracted light of each order. In each order of the diffracted light, since the angle at the direction cosine p where the change in the dimension has the greatest influence on the change in the light intensity is limited, a component that does not change much in the light intensity due to the change in the dimension is detected. Sensitivity will decrease.

  Here, as indicated by the term 17, the light intensity 18 increases or decreases in the component of the term 16 with the square of sinc (x) as an envelope with respect to the direction cosine p. Since the width s of the periodic structure is necessarily smaller than the interval d of the periodic structure, the period that increases or decreases with the square of sinc (x) with respect to the direction cosine p is the peak interval of the light intensity 18 with respect to the direction cosine p. Greater than / d.

  When a voltage is applied from the power source 13 to the opposing electrode patterns 3 that are alternately applied and grounded, lines of electric force 15 are generated between the electrode patterns. When the electric lines of force 15 pass through the coating film 5, Maxwell stress acts because the dielectric constant of the coating film 5 is different from that of air, and the coating film 5 is deformed by an electric field.

  In the case where the intensity of light transmitted when the width 7 of the periodic structure is s changes as the coating film 5 is deformed, and the width 7 is equivalent to the intensity of light when the width 7 is equivalently s ′, FIG. As shown in (d), the light intensity 19 with respect to the direction cosine p in the case of s becomes a characteristic of the light intensity 20 in s ′. It is assumed that the light intensity in the range of the angle of view 21 is detected using the image detector 12. At this time, the direction cosine p where the light intensity becomes zero changes in the square characteristic of sinc (x). Therefore, the image detector 12 detects diffracted light close to the diffraction angle where the diffraction angle is greater than 0 and the envelope is 0 for the first time, and the image processing device 14 obtains the portion where the light intensity change occurs in the image, The deformation of the coating film 5 can be detected as a change in light intensity.

  The magnitude of the deformation of the coating film 5 varies depending on the thickness of the film and the difference in the dry state, and the diffracted light shows a slight change in shape as a change in the light intensity. The difference can be detected as an uneven image. If there is no difference between images when voltage is applied and when voltage is not applied, it is possible to confirm the dry state as the coating film is dry. Thus, the unevenness of the coating film during drying can be detected by applying a voltage.

  Although unevenness of the periodic circuit pattern is also visible, the unevenness of the coating film can be detected by using a circuit pattern with high dimensional accuracy and detecting the unevenness caused by the difference between the voltage ON and OFF.

<Embodiment 2>
A second embodiment of the present invention described in claim 2 will be described with reference to FIGS. When the width 7 of the periodic structure is s, the light intensity 22 with respect to the direction cosine p is, when the coating film 5 is deformed by application of the voltage of the power supply 13 and the width 7 of the periodic structure is equivalently s ′, The light intensity is 23. Here, the light intensity is detected by the image detector 12 at the field angle 24 or the field angle 25 at which the diffracted light intensity decreases in the side lobe of the diffracted light. Thereby, in the case where the width 7 of the periodic structure is s and in the portion where the coating film is deformed and the width 7 of the periodic structure is equivalently s ′, a difference in light intensity between the two occurs, so that the periodic structure Defects can be detected as a light intensity distribution.

<Embodiment 3>
A case where the light source is used under the same conditions as in the first embodiment except that light of multiple wavelengths is used will be described with reference to FIGS. The substrate 4 is irradiated with multi-wavelength light from the light source 1 as substantially parallel light by the collimator lens 2. When the width 7 of the periodic structure 6 is s, when the wavelength is λ, the light intensity is 26 with respect to the direction cosine p, and when the wavelength is λ ′, the light intensity is 27 with respect to the direction cosine p. Here, when the coating film 3 is deformed by application of the voltage of the power source 13 and the width 7 of the periodic structure 6 is equivalently s ′, the light intensities at the wavelengths λ and λ ′ are the light intensity 28 and the light intensity, respectively. 29.

  In multi-wavelength light, diffracted light is detected using the image detector 12 at an angle of view 30 that is close to the diffraction angle at which the light intensity of the first side lobe becomes zero at all wavelengths. By obtaining a portion where the intensity of light changes, the coating film 5 is deformed by application of the voltage of the power source 13 and the film thickness and drying of the coating film 5 when the width 7 of the periodic structure is equivalently s ′. Unevenness in the difference in state can be detected as a change in light intensity.

  When the diffracted light is detected using the image detector 12 at an angle of view close to the diffraction angle at which the light intensity of the first side lobe is zero at all wavelengths, the light source is multi-wavelength. At the diffraction angle at which the intensity is zero, the sensitivity to the dimensional change of the periodic structure is poor, and even when the angle is too far from the diffraction angle at which the intensity is zero, the ratio of the light intensity that does not change due to the dimensional change increases.

  In addition, it is difficult to set the angle of view for single-wavelength substantially parallel light. Therefore, when the number of wavelengths is increased, the sensitivity is increased at any wavelength, so that the dimensional change can be easily detected with a high sensitivity by setting the angle of view.

  As described above, the substrate 4 is shown as an example in which the illumination light from the light source 1 passes through the periodic structure 6. In the substrate 4, when the periodic structure 6 reflects light and the portion other than the periodic structure 6 does not reflect light, the same effect can be realized by irradiating the substrate 4 with the light source 1 from the same direction as the image detector 14. .

<Embodiment 4>
A case where the light source used is the same as that of the second embodiment except that the light source is multi-wavelength light will be described with reference to FIGS. The substrate 4 is irradiated with multi-wavelength light from the light source 1 as substantially parallel light by the collimator lens 2. When the width 7 of the periodic structure 6 is s, when the wavelength is λ, the light intensity is 31 with respect to the direction cosine p, and when the wavelength is λ ′, the light intensity is 32 with respect to the direction cosine p. Here, when the coating film 3 is deformed by application of the voltage of the power source 13 and the width 7 of the periodic structure 6 becomes s ′, the light intensities at the wavelength λ and the wavelength λ ′ are the light intensity 33 and the light intensity 34, respectively. It becomes a characteristic.

  Here, the light intensity is detected by the image detector 8 at the angle of view 35 or the angle of view 36 where the diffracted light intensity decreases in the side lobes of the diffracted light of multiple wavelengths. As a result, unevenness in the difference in film thickness and dry state of the coating film 5 when the coating film 5 is deformed and the width 7 of the periodic structure 6 is equivalently s ′ by application of the voltage of the power source 13 It can be detected as a change.

  From the above, by the coating film unevenness measuring method and measuring apparatus of the present invention, in the drying process of the coating film in which a coating material such as ink or polymer resin solution is applied to the substrate, the periodic electrode pattern formed on the substrate is formed. An electric field is generated by applying a voltage, and the unevenness in the drying process of the coating film can be detected from the diffracted light of the coating film deformed by the electric field.

DESCRIPTION OF SYMBOLS 1 ... Light source 2 ... Collimating lens 3 ... Electrode pattern 4 ... Transparent substrate 5 ... Coating film 6 ... Periodic structure 7 ... Periodic structure width 8 ... Periodic structure Interval 9 ... Distance 10 ... Distance 11 ... Diffraction angle 12 ... Image detector 13 ... Power source 14 ... Image processing device 15 ... Field of electric force 16 ... Section 17 Item 18: Light intensity 19: Light intensity 20: Light intensity 21 ... Angle of view 22 ... Light intensity 23 ... Light intensity 24 ... Angle of view 25 ... Angle of view Angle 26 ... Light intensity 27 ... Light intensity 28 ... Light intensity 29 ... Light intensity 30 ... Angle of view 31 ... Light intensity 32 ... Light intensity 33 ... Light intensity 34 ... Light intensity 35 ... Field angle 36 ... Field angle

Claims (6)

  A coating film is formed on a transparent substrate having a periodic electrode pattern formed on the surface, a voltage is applied to the electrode pattern, and substantially parallel light is irradiated. A method for measuring coating film unevenness, comprising detecting zero-order diffracted light close to a diffraction angle at which the light intensity becomes zero.   2. The method for measuring coating film unevenness according to claim 1, wherein the diffracted light is image-detected at a diffraction angle at which the diffracted light intensity is lower than the peak intensity in the side lobe of the diffracted light.   The coating film unevenness measuring method according to claim 1, wherein the light irradiation is performed with multi-wavelength substantially parallel light. A transparent substrate having a periodic electrode pattern formed on the surface;
A power source for applying a voltage to the electrode pattern;
An image that includes a light source for irradiating the coated film on the transparent substrate with light and a collimator lens that makes light from the light source substantially parallel light, and detects an image of diffracted light generated from the film by light irradiation. A detector;
A coating film inspection apparatus comprising:
Of the diffracted light generated when the coating film is applied on a transparent substrate having a periodic electrode pattern formed on the surface, a voltage is applied to the electrode pattern, and the coating film is irradiated with light, the first A coating film unevenness measuring apparatus for detecting zero-order diffracted light close to a diffraction angle at which the light intensity of a side lobe becomes zero.   5. The coating film unevenness measuring apparatus according to claim 4, wherein an image of the diffracted light is detected at a diffraction angle at which the diffracted light intensity is lower than the peak intensity in the side lobe of the diffracted light.   6. The coating film unevenness measuring apparatus according to claim 4 or 5, wherein the light irradiation is performed with substantially parallel light having multiple wavelengths.

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