JPH08128921A - Surface reflectance measuring method for polarizing film product - Google Patents

Abstract

PURPOSE: To accurately detect surface reflectance of a polarizing film product without touching on the product itself and any loss of the product. CONSTITUTION: In the measuring method of surface reflectance for a polarizing film product, a polarizer is arranged so that the polarizing axis of the polarizer perpendicularly crosses to the polarizing axis of the polarizing film product on the measuring surface side, outgoing light is struck to the polarizing film product from the front surface of the polarizer and the reflecting light from the product is measured through the polarizer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring the surface reflectance of a polarizing film product used for optical parts such as liquid crystal displays.

[0002]

2. Description of the Related Art In recent years, liquid crystal displays that have been used in the fields of televisions, office automation equipment and the like have been expanding their application fields such as use as monitors for video cameras and as information terminals in automobiles. In the field of application of monitors for video cameras and in-vehicle information terminals, the reflection of external light on the surface of the display greatly affects the display quality of the display. Since the polarizing film product is mounted on the surface of the liquid crystal display, it is necessary to know the surface reflectance of the polarizing film product. In order to accurately measure the surface reflectance of a polarizing film product, it is necessary to prevent light reflection on the back side of the measurement surface. As a method of preventing this back surface reflection, a method of roughening the back surface, a method of applying black paint to the back surface, a method of combining both methods, and the like have been performed.

[0003]

In a polarizing film product, the antireflection treatment on the back surface for measuring the surface reflectance, that is, the method of roughening the back surface, the method of applying black paint on the back surface, etc. are complicated. Moreover, the product is lost because the product is soiled. The present invention provides a method of accurately detecting the surface reflectance of a polarizing film product without any modification.

[0004]

Means for Solving the Problems That is, the present invention provides a method for measuring the surface reflectance of a polarizing film product, in which a polarizing axis of the polarizer is orthogonal to the polarizing axis of the polarizing film product on the measurement surface side. The present invention provides a method for measuring the surface reflectance of a polarizing film product, which is characterized in that the light is emitted from the front surface of the polarizer and the reflected light from the polarizing film product is measured through the polarizer.

The polarizing film product of the present invention uses a polarizing film as a basic constituent material. For example, not only a single polarizing film, but also a polarizing film coated with an adhesive, a polarizing film surface with antireflection treatment, a polarizing film surface with another film, especially an antireflection film. This corresponds to a laminated product, a polarizing film laminated with a retardation film on the back surface, a polarizing film laminated to a liquid crystal display, and the like.

The polarizer of the present invention is a so-called linear polarizer that generates linearly polarized light, and is described in WA Polaris and its Applications, Chapter 3 Types of Polarizers and Their Performance Is. Among them, the polarizing film is most conveniently used, and the polarizing film having both surfaces subjected to antireflection treatment is practically excellent.

The polarizer of the present invention needs to be arranged so that the polarization axes of the product and the polarizing film product to be measured are orthogonal to each other. If the polarization axes are not orthogonal, the measurement accuracy will be low.

The two may be arranged in close contact with each other, may be simply overlapped with each other, or may be spaced to some extent. For example, if the polarizing film product to be measured is different from each leaf, it can be closely attached or can be overlapped for measurement. If the polarizing film product to be measured is a long product, a polarizer can be placed at a predetermined position and the polarizing film product can be run at a certain interval and continuously measured in the length direction.

To measure the reflectance of a polarizing film product, an apparatus having a function of emitting a predetermined amount of light from a light source and a photometer for measuring the amount of reflected light is used. In addition,
Such devices are commercially available.

When a polarizer is placed on the polarizing film product to be measured, an output light beam is applied from the front surface of the polarizer by the device, that is, light is applied to the surface of the polarizing film product through the polarizer, The reflectance is also calculated by receiving the reflected light through the polarizer and measuring the amount of light.

As an example of the reflectance measuring method of the present invention,
A polarizer is placed on a standard sample having a surface reflectance R ₀ for light of a specific wavelength, and the intensity P of the light reflected by the light of that wavelength is set.
Ask for ₁ . The standard sample is removed from the above and only the polarizer is measured in the same manner to obtain the intensity P ₂ of the reflected light from the polarizer. The polarizing film product to be measured is placed at the same position as the standard sample, and the same measurement is performed to obtain the intensity P _{3 of the} reflected light. From these P ₁ , P ₂ , P ₃ and R ₀ , the surface reflectance R _s of the polarizing film product to be measured can be obtained by the following [Equation 1].

[0012]

## EQU1 ## R _s = (P ₃ −P ₂ ) ÷ (P ₁ −P ₂ ) × R ₀

If a computer is connected to the above apparatus and P ₃ is measured with the values of P ₁ , P ₂ and R ₀ measured in advance, the calculation of the above formula is performed and the value of the surface reflectance is instantaneously calculated. Can be obtained.

[0014]

EXAMPLES The measuring methods and materials used in the examples are as follows. -Measurement of reflectance: Using the MCPD-1000 manufactured by Otsuka Electronics Co., Ltd., the reflectance spectrum in the visible light region of 400 to 700 nm was measured.・ Polarized film products to be measured: Sample 1: Non-reflective polarizing film SK manufactured by Sumitomo Chemical Co., Ltd.
1832AP1-HC-AR laminated on a glass plate. Sample 2: Sumitomo Chemical Co., Ltd. polarizing film SK1832AP
1-HC laminated on a glass plate. -Polarizer: Sumitomo Chemical Co., Ltd. polarizing film SK1832
Both sides of A have anti-reflection treatment. Standard sample: a 250 μm thick polymethylmethacrylate film having a 5 μm thick hard coat layer on the front surface and a black paint on the back face, and the surface reflectance R _{0 for} each wavelength is 400 n.
m; 4.48, 500 nm; 4.20, 600 nm; 4.12, 700 nm; 4.10).

Reference Examples 1, 2 Samples 1 and 2 were coated with black paint on the back surface and the reflectance was measured as they were. The reflectance spectrum of the measurement result is shown in FIG. This is the surface reflectance of each sample.

Comparative Examples 1 and 2 Samples 1 and 2 were directly measured for reflectance. The reflectance spectrum of the measurement result is shown in FIG. Compared with the result of FIG. 5, the reflectance value is about 1% larger. This is due to the influence of the back surface reflection of the sample, and it is understood that the surface reflectance cannot be accurately obtained by this method.

Examples 1 and 2 The distance between the light source of the reflectance measuring instrument and the standard sample was 4 mm, and a polarizer was placed at a position 1 mm away from the standard sample on the light source side to measure the intensity P _{1 of the} reflected light. Next, the standard sample was removed at the same position, and the intensity P ₂ of the reflected light of only the polarizer was measured.
Subsequently, each of the polarizing film product samples 1 and 2 to be measured was placed at the position where the standard sample was present, and the intensities P ₃ -1 and P ₃ -2 of the respective reflected lights were measured. From these values, the surface reflectances of Sample 1 and Sample 2 were obtained from the above [Equation 1]. The results are shown in Fig. 3. The results are in good agreement with the values of the surface reflectance shown in FIG. 1 of Reference Examples 1 and 2, and it can be seen that the surface reflectance can be measured by this method.

[0018]

According to the present invention, the polarizing film product has
The surface reflectance of the product can be easily and accurately measured without any loss of the product.

[Brief description of drawings]

FIG. 1 is a surface reflectance spectrum diagram of Reference Examples 1 and 2.

FIG. 2 is a surface reflectance spectrum diagram of Comparative Examples 1 and 2.

FIG. 3 is a surface reflectance spectrum diagram of Examples 1 and 2.

Claims (1)

[Claims] 1. A method for measuring the surface reflectance of a polarizing film product, wherein a polarizer is arranged on the side of the measuring surface so that its polarization axis is orthogonal to the polarization axis of the polarizing film product, and the front surface of the polarizer is measured. And a reflected light from the polarizing film product is measured through the polarizer, and a surface reflectance measuring method of the polarizing film product.