JP2007010403A - Measuring technique for film thickness of antireflective layer of antireflective film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a measuring technique for the film thickness of the antireflective layer of an antireflective film capable of measuring continuously the film thickness of the antireflectve layer over the full width of a film during driving condition of a film under manufacturing of an antireflective film. <P>SOLUTION: The measuring technique for the film thickness of the antireflective layer of an antireflective film, in which the emulsion side of the antireflective layer of the antireflective film and reflected light is irradiated long-wave ultraviolet light of wavelength of 365 to 400 nm from both the emulsion side and the rear side is forced to interfere mutually, is characterized by measuring the film thickness using gray-scale optical images (optical signals) acquired from the interference. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for measuring the film thickness of a transparent antireflection layer of an antireflection film.

  As a general method for measuring the film thickness of the antireflection layer of the antireflection film, the thickness is calculated by comparing the spectral characteristics of normal thickness with the spectral characteristics using visible light. However, according to this method, although it can be grasped by points, the film thickness distribution on the entire surface of the large film cannot be obtained. If you take time, you can increase the number of measurement points and create a map, but you cannot measure the full width as if it is flowing in a line.

  The antireflection action of the antireflection film attached to the surface of the display is mainly classified into a method using a matte film and two types using thin film interference.

  The anti-reflection layer of the anti-reflection film using the interference of the thin film is an anti-reflection film set to a thickness of 540 nm × ¼ so that the green wavelength near the center value of 540 nm of visible light is mainly canceled by interference. Exists. When it is made of a material having a refractive index of about 1.36 at 540 nm × 1/4 = 135 nm, it is coated with a thickness of about 100 nm. If there is a variation in the thickness of this layer, interference does not occur correctly at 540 nm, the wavelength range causing the interference varies, and visual observation may appear uneven. Further, if there is a sudden thickness variation, a concave portion, or a convex portion, it is regarded as a point defect.

  For this reason, the thickness of the antireflection film must be fairly uniform. During the production of the antireflection film, the thickness of the antireflection layer should always be set to the full width of the film as if it were flowing in a line. Need to manage.

  The present invention has been made to solve the above-described problem, and during the production of an antireflection film, the film thickness of the antireflection layer can be continuously measured over the entire width of the film while the film is running. An object of the present invention is to provide a method for measuring the film thickness of an antireflection layer of an antireflection film.

  In order to achieve the above object, that is, in the invention according to claim 1, the film surface of the antireflection layer of the antireflection film is irradiated with ultraviolet light having a long wavelength region of 365 to 400 nm, and the film surface and the back surface of the film The thickness of the antireflection layer of the antireflection film is measured by measuring the thickness of the thin film based on the light image (light signal) of light and shade obtained by the interference between the reflected lights from Is the method.

  The present invention makes it possible to continuously measure the film thickness of the antireflection layer over the entire width of the film during the production of the web-like antireflection film. This measurement method enabled management of the uniform thickness of the antireflection layer during the production of the antireflection film.

Usually, the antireflection layer is made of a transparent resin having a thickness of 100 nm and a refractive index of about 1.35. With this configuration, as described above, the visible light incident on this layer interferes with the center at 540 nm because the length is about ¼ of the wavelength in the vicinity of green with a central value of 540 nm of visible light 400 to 750 nm. Wake up and not reflect.

  When moving away from 540 nm, for example, light of 400 nm or 750 nm is slightly reflected as much as interference cannot occur. Therefore, by changing the thickness of this layer, the spectral characteristics of the reflected light change, and the composition of the slight reflected light also changes. This is a conventional film thickness measurement method.

  In contrast to the above-described conventional film thickness measurement method, according to the film thickness measurement method of the present invention, this is the case of ultraviolet rays close to the visible light range of about 380 nm. 380 nm × 1/4 = 95 nm, 95 nm × 1.35 = 66.7 nm, that is, total interference occurs when the film thickness is 66.7 nm, and total interference occurs even at about 130 nm. When the thickness is 66.7 nm, the reflected light is the least because it is a quarter wavelength of the UV wavelength of 380 nm.

  In the case of 130 nm, since the wavelength is ½, the reflected light is doubled and becomes brightest. Therefore, if the film thickness changes between 66.7 and 130 nm, the change in the thickness centered on 100 nm is displayed as it is by using the ultraviolet light of about 380 nm.

  Hereinafter, in the method for measuring the film thickness of the antireflection layer of the antireflection film of the present invention, an embodiment using a measuring device using linear linear ultraviolet illumination light will be described in detail with reference to the drawings.

  FIG. 1 is an overall perspective view of the device A of the present invention, in which 1 is a light source device including an ultraviolet wavelength region, and 4 is light in an ultraviolet wavelength region that causes interference among the wavelength regions of light emitted from a visible light source device. The ultraviolet light transmitting optical filter 2 to be selected is a linear light whose guide end 2a is connected to the light generation position of the light source device 1 and guides visible light including the ultraviolet wavelength region emitted from the light source device 1 in a line shape. A guide 3 is a rectangular plate-shaped light guide to which the tip 2b of the linear light guide 2 is connected, 11 is a light image detection means such as a CCD camera, and 12 is an ultraviolet wavelength of 360 nm or more and less than 400 nm. An imaging lens unit having a high transmittance of about 60 to 70% on the long wavelength side in the ultraviolet region (for example, a high transmittance lens using optical glass BK7), B is the object to be inspected, and S is the width of the object to be inspected B Illuminated in the W direction It is a straight line-shaped ultraviolet illumination light width d.

  The rectangular plate-shaped light guide 3 is fixedly arranged parallel to the width W direction of the inspection object B with its lower end directed toward the inspection object B.

  Visible light including the ultraviolet wavelength region emitted from the light source device 1 passes through the ultraviolet light transmission optical filter 4 that selects light in the ultraviolet wavelength region, and only the light L1 in the ultraviolet wavelength region causing interference of the linear light guide. Is incident on the base end portion 2a of the line-shaped light guide 2 connected to the light source device 1, and is guided along the line-shaped light guide 2 from the base end portion 2a to the tip end portion 2b of the guide 2 in a line shape. .

The front end portion 2b of the line-shaped light guide 2 is connected to and attached to the upper end portion of a rectangular plate-shaped light guide 3 fixedly arranged in parallel to the width W direction of the object B to be inspected. The light L1 is irradiated into the plate-shaped light guide 3 from the front end portion 2b of the line-shaped light guide 2, and passes through the guide 3 to be inspected as linear linear ultraviolet illumination light L1 having an illumination width d from the lower end portion. The surface of the body B is irradiated. In the device of the present invention, one or a plurality of light source devices 1 can be arranged, and one or a plurality of line light guides 2 can be connected to each light source device 1. In addition, one or a plurality of light guides 3 can be connected to the upper end of the plate-shaped light guide 3.

  The light source device 1 including the ultraviolet wavelength region shown in FIG. 1 is a lamp house type light source device that emits visible light including a large amount of ultraviolet wavelength region using a mercury discharge lamp, and the light emitted from this lamp is visible from the ultraviolet light region. It emits light of various wavelengths up to the light range, and actually, light of various wavelengths from 200 nm to 700 nm is emitted.

  Among various wavelengths from 200 nm to near 700 nm, the wavelength in the visible light region is about 400 nm to 700 nm, but the wavelength in the ultraviolet region is about 200 nm to less than 400 nm, and the wavelength in the ultraviolet region. In particular, ultraviolet light having a wavelength of about 300 nm to less than 400 nm or about 360 nm to less than 400 nm is emitted most strongly.

  In the case of the illumination inspection by the linear line-shaped ultraviolet illumination light L using the light source by the light source device 1 including the ultraviolet wavelength region as in the device of the present invention, first, a camera (for example, a linear CCD camera) as the optical image detection means 11 is used. Sensitivity is higher in the visible light range than in the ultraviolet light range unless a dedicated camera for ultraviolet light is used, so even if something on the object to be inspected is detected as an optical image by ultraviolet light, the camera sensitivity is higher. The high visible light erases all the light image of the object to be inspected by ultraviolet light or makes it difficult to discriminate it as an image.

  Therefore, it is necessary to cut all visible light having a wavelength of 400 nm or more from the light source light by the visible light source device 1 including the ultraviolet wavelength region so that only the ultraviolet light is obtained. Even in the case of ultraviolet light, ultraviolet light having a short wavelength of 350 nm or less deteriorates multi-component glass fibers or lenses generally used for light guides such as the line light guide 2 and the plate light guide 3. There is a phenomenon to bring about, so unless you use quartz fibers or lenses, you also need to cut them. This is not the case with quartz.

  Therefore, in the device of the present invention, the filter 4 that transmits the light L1 having a wavelength of 350 nm to less than 400 nm is mounted in the lamp house of the visible light source device 1 including the ultraviolet wavelength region.

  From the visible light source device 1, a line-shaped light guide 2 and a plate-shaped light guide 3 are connected in this order. As L1, an optical image by reflected light L2 reflected by the surface of the inspection object B (for example, the continuously moving sheet B or the stationary sheet B) illuminated by the illumination light L1 is detected as an optical image. The image is picked up by the optical image detecting means 11 such as a linear CCD camera (line CCD camera) through the lens 12 of the means 11.

  According to this captured image, the normal thickness portion is displayed in about 128 gradations, and the thicker portion is displayed in a whitish and thin portion dark.

  According to the method for measuring the film thickness of the antireflection layer of the antireflection film, the film thickness of the antireflection layer can be continuously measured over the entire width of the film during the production of the web-shaped antireflection film. it can. This measurement method enables management of the uniform thickness of the antireflection layer during the production of the antireflection film.

It is explanatory drawing explaining an example of the method of measuring the film thickness of the antireflection layer of the antireflection film of this invention.

Explanation of symbols

A ... inspection device B ... inspected object 1 ... visible light source device 2 including ultraviolet light ... line light guide 2a ... guide base end 2b ... tip 3 ... plate light guide 4 ... optical filter 11 ... optical image detection means 12. Optical lens part

Claims (1)

  The film surface of the antireflection layer of the antireflection film is irradiated with ultraviolet light having a long wavelength region of 365 to 400 nm, and the reflected light from the film surface and the back surface of the film are caused to interfere with each other, and the light and shade obtained by the interference A method for measuring the film thickness of an antireflection layer of an antireflection film, wherein the film thickness of the thin film is measured by an image (optical signal).

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