JPS62116204A - Method and apparatus for measuring contact area - Google Patents

Abstract

PURPOSE:To enable highly accurate quantification and the judgement of the increase and decrease in a contact surface due to a change with time, by quantifying the reflected light from the specimen mount surface of a triangle prism and quantifying a contact area on the basis of the measured value thereof. CONSTITUTION:The light emitted from a light source 2 is incident on an equilateral right-angled prism 1 from the surface B thereof toward the direction (specimen) of the surface A thereof and this incident light (a) is reflected from the surface A to obtain reflected light (b) which is, i turn, taken out from the surface C of the prism 1. When the light (a) is reflected from the surface A, at a contact part where the order of the gap between the surface of the pressure-sensitive adhesive of a pressure- sensitive adhesive tape 4 and the surface A came to about a function of the wavelength of incident light, the contact state of the surface A and the tape 4 is reflected to the reflected light (b) as the magnitude of reflectivity by the tunnel effect acting between the prism 1 and the pressur-sensitive adhesive. Next, reflected light (c) is received and measured by an optical sensor 3 and the light absorbing ratio on the surface A is calculated from the measured value and a measured value obtained when the incident light (a) is totally reflected fro the surface A without adhering the tape 4 to the surface A to quantify a contact area.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention provides a novel contact area measuring method with excellent fixing accuracy, which can be preferably applied to determining the effective bonding area of an adhesive to an adherend. This is related to the device.

The effective adhesive area of conventional adhesives or adhesive products such as adhesive tapes to adherends is an important factor in evaluating their adhesive performance. Therefore, it is necessary to know how much effective adhesive area an adhesive or adhesive product can have under specific adhesive conditions such as temperature and pressure force.

Conventionally, the contact area measurement method for adhesive tape, etc., involves attaching the adhesive layer of adhesive tape to a transparent plate made of a slide glass, taking a photograph, and binarizing it into dark and white areas. A method of quantifying by determining the area ratio was known. In other words, at the contact area between the transparent plate and the adhesive layer, the incident light passes through and the reflected light decreases, resulting in a dark area, while at the non-contact area, most of the incident light is reflected, resulting in a white area, so the brightness and darkness of the area is different. This is a method of quantifying by determining the distribution area of .

Problems to be Solved by the Invention However, in the conventional method, it is difficult to distinguish when the difference between brightness and darkness is small or when the contact area is minute, and there has been a problem that the quantitative accuracy is poor.

Another problem was that it was not possible to know the contact level, such as a gap in the contact portion, which is related to adhesive strength and the like.

Means for Solving the Problems The present invention overcomes the above-mentioned problems, and includes quantifying the reflected light from the sample mounting surface of the triangular prism and quantifying the contact area based on the measured value. As a principle.

That is, in the present invention, a specimen is brought into contact with a first surface constituting a triangle of a triangular prism, a light beam is made incident on the specimen from the second surface, and the reflected light is extracted from the third surface. A contact area measuring method characterized by quantifying light and quantifying the contact area of a specimen based on the value, a triangular prism, and three constituting triangles of the triangular prism.
at least one light source for making a light beam incident from one of the surfaces, and a light receiver for detecting the reflected light reflected from one of the remaining two surfaces of the triangular prism and emitted from the last remaining surface. The present invention provides a contact area measuring device characterized by comprising a device.

A specimen is placed on one of the three surfaces (surface A) that makes up the triangle of a triangular prism, and a light beam is made incident on one of the remaining two surfaces (surface B), and the reflection from the surface on which the specimen is attached is measured. By extracting the light from the remaining surface (C surface), it is possible to prevent the reflected light from the C surface from being mixed with the light reflected from the B surface, which is the light incident surface.As a result, the state of the A surface can be accurately (reflected) The reflected light can be extracted from the C-plane, and even minute differences in the reflected light due to the A-plane can be determined.

Further, the reflectance on the A surface differs between the contact portion and the non-contact portion due to the tunnel effect and the like, and even in the contact portion, it differs depending on the wavelength of the incident light.

As a result, it becomes possible to determine the contact level by changing the wavelength of the incident light.

EXAMPLE The method of the present invention will be explained below based on the illustrated example of the apparatus of the present invention.

In the figure, ■ is an isosceles right angle prism, and 2 is a lens 2a.
The reference numeral 3 designates a light source constituting a collimator, a light sensor 3 as a light receiver, and an adhesive tape 4 as a specimen consisting of a pressure-sensitive adhesive layer 4a and a support base material 4b.

The adhesive tape 4 is pressed under predetermined bonding conditions to the face (side A) of the right-angled apex of the three faces forming the triangle of the isosceles rectangular prism 1 via the pressure-sensitive adhesive layer 4a. There is. The light source 2 is arranged so that a light beam can be incident on the specimen from one of the remaining two surfaces (surface B) of the three surfaces forming the triangle of the isosceles right-angle prism 1. The optical sensor 3 is arranged so as to be able to receive reflected light extracted from the remaining one surface (C surface) of the three triangular surfaces of the isosceles right angle prism l.

Quantification of the contact area using the above device is performed as follows.

That is, first, the light beam emitted from the light source 2 is made incident on the isosceles rectangular prism 1 from the B side toward the A side (specimen).
The reflected light of this incident light a on the A plane is taken out from the C plane.

When incident light a is reflected on surface A, the prism and pressure sensitive A tunnel effect occurs due to the small difference in refractive index of the adhesive layer, and a portion of the incident light is transmitted to the adhesive tape side, reducing its reflectance. As a result, the state of contact between the A side and the adhesive tape changes the reflectance and is reflected in the reflected light.

Next, the reflected light taken out from surface 0 is measured by the optical sensor 3, and the measured value and the value obtained when the incident light a is reflected on the entire surface of surface A without attaching adhesive tape 4 to surface A. The contact area is quantified by determining the light absorption rate on the A side from the measured values.

The contact level can be determined by performing the above-mentioned quantitative operation of the reflected light by changing the wavelength of the incident light, and examining the change in light absorption rate due to the difference in wavelength or the change in the quantified contact area. . In other words, the larger the light absorption rate for light rays on the short wavelength side, or the larger the contact area quantified when using light rays on the short wavelength side, the smaller the gap between side A and the surface of the pressure-sensitive adhesive layer becomes. This means that there are many, so this makes it possible to make a determination.

In addition, when making the incident light a enter from 8 surfaces, it is important to make it incident so that the angle of incidence on the A surface is equal to or greater than the critical angle, so that total reflection occurs in the non-contact parts, in terms of quantitative accuracy. preferable. Incidentally, the critical angle at the interface between the isosceles rectangular prism and air in the example is about 40 degrees.

In the above-mentioned embodiment, the total reflection condition is satisfied in the ordinary atmospheric inspection, and the normal incidence and 0
Although an isosceles rectangular prism is used to enable light reflected from a surface to be taken out at a vertical angle, the present invention is not limited to this, and any triangular prism may be used regardless of its form. be able to.

Further, the surface of the triangular prism that contacts the specimen may be smooth, or may be arbitrarily roughened or uneven. The surface that comes into contact with the specimen, that is, the surface with which the specimen is attached, is roughened to a predetermined surface roughness in advance, and this is used for inspection to determine the contact area depending on the surface roughness of the specimen attachment surface or the surface roughness of the specimen. As a result, it is possible to estimate with high reliability the contact area corresponding to the surface roughness of the actual adherend.

Although light sources are necessary in the device of the present invention, there is no limitation on the number of light sources, and they may be singular or plural, and in the case of multiple light sources, they may be used in combination with those that emit light rays of different wavelengths. There may be.

On the other hand, the light receiver can be used without any restrictions as long as it is capable of quantifying the amount of light. Generally, a light sensor such as a photoconductive element or a photodiode is used.

The method of the present invention can be used not only for quantifying the contact area of adhesive products such as adhesives and adhesive tapes, but also for determining the surface smoothness of glass plates, films, etc. using the contact area as a criterion. be able to.

Furthermore, it is also possible to perform image analysis of reflected light by combining the apparatus of the present invention with an image analysis system, and with this, it is possible to know the shape of the contact portion and the distribution state of its contact level.

Effects of the Invention According to the present invention, since the contact area is quantified based on the degree of reflection of light rays on the adherend surface using an optical method using a triangular prism, the quantification can be performed with high accuracy. It is possible to detect subtle increases and decreases in the contact area due to changes over time, and it is also possible to determine the contact level at the contact portion.

[Brief explanation of drawings]

The figure is a schematic diagram representing an embodiment of the device of the present invention. 1: Isosceles right angle prism 2: Light source 3: Optical sensor 4; Adhesive tape A side: Sample attachment side 8th surface: light incidence surface Surface 0: Reflected light extraction surface a. Incident light double reflected light

Claims (1)

[Claims] 1. A specimen is brought into contact with the first surface forming a triangle of a triangular prism, a light beam is made incident on the specimen from the second surface, and the reflected light is extracted from the third surface. A contact area measuring method characterized by quantifying reflected light and quantifying the contact area of a specimen based on the value. 2. The method according to claim 1, wherein the triangular prism is an isosceles right angle prism. 3. The method according to claim 2, wherein the first surface faces a right apex angle. 4. The method according to claim 1, wherein the first surface that is brought into contact with the specimen is a rough surface. 5. The method according to claim 1, wherein the specimen is an adhesive layer such as a pressure-sensitive adhesive layer. Method. 6. A triangular prism, at least one light source for allowing a ray to enter from one of the three surfaces forming the triangle of the triangular prism, and a light beam reflected by one of the remaining two surfaces of the triangular prism. A contact area measuring device comprising: a light receiver for detecting reflected light emitted from the last remaining surface. 7. The device according to claim 6, wherein the triangular prism has a rough reflecting surface for incident light.