JPH0332047B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a reflective light receiving element. DESCRIPTION OF THE PREFERRED EMBODIMENTS A reflective liquid crystal display element, which is most commonly used as an example of the prior art, will be described below with reference to the drawings. FIG. 1 is a cross-sectional configuration diagram of a reflective liquid crystal display element, a diffuse reflector, and a miniature light bulb, and FIG. 2 is a plan view thereof. As shown in FIGS. 1 and 2, the basic configuration of the reflective liquid crystal display element 1 is as follows: A liquid crystal 1b is sealed between a pair of transparent electrode substrates 1a, and placed on the upper and lower surfaces of the liquid crystal 1b. Linear polarizing plates 1c, 1c (hereinafter abbreviated as polarizing plates 1c, 1c), and a diffuse reflection plate 2 consisting of a plastic film 2a and a reflective layer 2b are placed on the lower surface of the reflective liquid crystal display element 1 with an air layer 15 in between. A voltage is applied between the electrodes, and display is performed by the electric field effect of the liquid crystal 1b. However, since the liquid crystal 1b itself does not emit light, it usually requires external light sources such as sunlight and an indoor light, and in the case of a dark place without an external light source, a miniature light bulb 3 placed on the side of the diffuse reflection plate 2 is mainly used.
Requires an internal light source. A diffuse reflection plate 2 is required for the purpose of converting external and internal light sources into diffused light. A plastic film 2 is generally used as the diffuse reflector 2 used in such a reflective liquid crystal display element.
A matte finish with a surface roughness of 0.5 to 10 .mu.m is applied to both or one side of the substrate 2, such as a satin finish or a geometric pattern, and a reflective layer 2b made of a metal film is provided on one side. This matte treatment method includes a method in which an extrusion roll or mold is previously matted by a chemical or mechanical method to form the plastic film 2a and is transferred at the same time, and a method in which the plastic film 2a is formed and then a mechanical secondary Processing methods are common, but these have the following drawbacks. In other words, in the transfer method, even if the matte processing of the extrusion roll or mold is initially uniform and without variations, variations in the transfer may occur depending on the processing conditions for obtaining various characteristics such as the thickness and shape of the transparent body. As the number of processes increases, the matted surface of the extrusion roll or mold becomes unevenly worn, making it difficult to obtain a uniform and consistent matted surface. Further, in the secondary processing method, the mechanical matting processing conditions change due to variations in the thickness, shape, etc. of the plastic film 2a, and it is difficult to obtain a uniform matte surface without variations. Therefore, it is difficult to obtain a diffusion effect above a certain level with the above-mentioned diffuse reflector 2 having a pine surface, and especially when the light source is a miniature light bulb 3, the brightness becomes extreme as the distance from the light source increases. In many cases, the display became difficult to read. As described above, even if the light sources from the external and internal light sources are converted into diffused light using only the diffuse reflection plate 2, there is a limit to the brightness and spread of light. The present invention aims to solve these problems, and its purpose is to provide an inexpensive reflective light-receiving element that has an excellent light diffusing effect that cannot be obtained with a diffuse reflector alone. It is in. In the reflective light-receiving element of the present invention, in the reflective light-receiving element installed above with a diffuse reflector and an air layer interposed therebetween, at least one type of cellulose resin is coated on the lowermost surface of the reflective light-receiving element. It is characterized by being coated with a cured film of a mixture of seeds and a hydrolyzed organometallic compound. By applying a mixture of at least one type of cellulose resin and at least one type of hydrolyzable organometallic compound to the polarizing plate constituting the bottom surface of the element and baking it, an extremely uniform polyhedron is formed on the surface of the polarizing plate. It became possible to form a cured film with an uneven surface, and the cured film, the air layer under the cured film, and the diffuse reflector formed a light reflecting section with an excellent light guiding layer. The light diffusivity of the cured film exceeds that of the diffuse reflection plate, and the light transmittance of the polarizing plate that is reduced by coating with the cured film is 1.
The amount was so small that it could not be visually confirmed with the naked eye. Numerous experiments have revealed that a unique uneven surface can be obtained by applying a treatment solution in which cellulose resin is dissolved in an appropriate solvent to a polarizing plate and baking it at an appropriate temperature. The solvent needs to be semi-soluble and does not completely dissolve the cellulose resin, and when the treatment liquid is applied on a polarizing plate, the content of the cellulose resin in the coating layer on the polarizing plate is It is thought that variations occur in the amount, and under appropriate firing conditions, the variations are not eliminated and form a film, forming a unique uneven surface.
Although the above film exhibits excellent light diffusivity and high light transmittance, the adhesion to the polarizing plate, the hardness of the film,
Although it is inferior in abrasiveness and chemical properties, these can be improved by adding at least one hydrolyzable organometallic compound to the treatment liquid. In a solvent containing cellulose resin such as hydroxypropyl cellulose, hydroxyethyl cellulose, cellulose nitrate, cellulose acetate, etc., Si, as a metal element,
Ti, Zr, Ta, Ge, Al, Cr, Nb, Hf, V, Mo,
At least one monomer or multimer such as an alkoxy compound, an allyloxy compound, or a chelate compound containing W, Ga, In, Sn, Sb, Fe, etc. is added and thoroughly stirred to obtain a treatment solution. After applying the treatment liquid to the surface of the polarizing plate by a known method such as a spray method, a dipping method, a spinner method, or a roll coater method, the treatment solution is heated and baked at 50 to 90°C for 30 minutes to 2 hours. The hydrolyzable organometallic compound reacts with the polarizing plate, the cellulose resin, and the hydrolyzable organometallic compounds to form a cured film having an uneven surface of a strong three-dimensional compound. Therefore, the adhesion between the three-dimensional compound and the polarizing plate is good, and the hardness is as high as 3H to 6H (pencil hardness), making it excellent in abrasion resistance. It is also unaffected by heat, light, humidity, and chemicals such as alcohol. In addition, cellulose resin, if we take hydroxypropyl cellulose resin as an example, has a molecular weight of 10,000~
2,000,000 is appropriate, and the concentration is 0.1 to 20 wt/v%, although it depends on the thickness of the cured film to be obtained (the film thickness is preferably in the range of 0.5 μm to 8 μm). The amount of the hydrolyzable organometallic compound is preferably 0.5 to 2.0 times the weight of the cellulose resin added. As described above, in a reflective liquid crystal display element in which a light-scattering cured film is coated on the polarizing plate constituting the lowermost surface of the element, and a diffuse reflector is further installed via an air layer, light is diffused. The effect must satisfy the conditions described below. The first condition is that the specular reflection glossiness (JIS
Z8741) at an incident angle of 45 degrees and 60 degrees, each or one of them must be at least 10% or more with respect to the reference surface (specular gloss on a glass surface with a refractive index of 1567 is 100%), and The glossiness at the acceptance angle when shifted by +5 degrees and -5 degrees from the direction of specular reflection is 80% of the glossiness of specular reflection.
It is necessary that there be more than one. The second condition is
In Figures 1 and 2, the diffusion effect of the miniature light bulb as an internal light source is shown in Figs.
% or more, measurement value 7 needs to be 7% or more, and measurement value 8 needs to be 5% or more. In carrying out the present invention, both of the above conditions must be satisfied simultaneously. The device of the present invention as described above has sufficient brightness for display, has a sufficient tolerance for reduction in brightness due to differences in the position of the light source or viewing position, and in the case of display using an internal light source, The decrease in brightness due to differences in distance from the light is slight, and the light diffusion properties are extremely excellent. In the present invention, a reflective liquid crystal display element using a polarizing plate as a reflective light-receiving element has been described, but the present invention can be applied to all reflective light-receiving elements, including liquid crystal display elements of other types. It is. Examples will be described below. Example The following ingredients were thoroughly stirred to prepare a treatment liquid. Hydroxypropyl cellulose resin 2g SH6040 (manufactured by Toray Silicone) 5g Ta (OC ₂ H ₅ ) ₅ 3g Ti (OC ₄ H ₉ ) ₄ 0.5g Si (OCH ₃ ) ₄ 1.5g Isopropyl alcohol 100ml A polarizing plate was placed in the treatment solution. Immerse it and pull it up at a constant speed of 15cm/mm. Immediately after that, baking was performed at 80°C for 30 minutes. Micrograph of the surface of the cathode ray tube of the present invention (×
100) is shown in the reference photo. The obtained polarizing plate is used as the lower polarizing plate of a reflective liquid crystal display element, and the element is assembled so that the diffuser reflecting plate is installed below the lower polarizing plate with an air layer in between. The glossiness and diffusion effect (brightness) in miniature bulbs were measured and the results were as follows.

【table】

[Table] The structure of this reflective liquid crystal display element and a diffuse reflector was designated as A. On the other hand, for comparison, the structure of a conventional reflective liquid crystal display element was designated as B, and the glossiness and diffusion effect (brightness) in a miniature light bulb were measured, and the results were as follows.

【table】

[Table] When comparing each structure of A and B using an external light source (indoor light) and an internal light source (miniature light bulb), A
shows sufficient brightness even when the direction of the external light source changes or the position of the eye changes, and in the case of an internal light source, shows sufficient brightness even when the distance from the light source increases, and provides satisfactory contrast for display purposes. be able to. However, in case B, if the direction of the external light source or the position of the eyes shifts slightly, the brightness will drop dramatically, and as the distance from the internal light source increases, the brightness will drop to the point where the display is almost invisible. This results in an unsatisfactory contrast. As described above, according to the present invention, the lowermost surface of the reflective light-receiving element is coated with a mixture of at least one type of cellulose resin and at least one type of hydrolyzable organometallic compound. Since a cured film having an extremely uniform polyhedral uneven surface is formed on the bottom surface of the substrate, for example, a light source is placed on the sides of the reflective light-receiving element and the diffuse reflector at a position corresponding to the air layer between the two. When placed, the light from this light source is simply diffused by the diffuse reflection of the diffuse reflector, so the amount of light is small at a position far from the light source of the reflective light-receiving element, and the brightness of the display is insufficient. Compared to the conventional technology, which has a structure that deteriorates, the present invention has the advantage that in addition to the diffused light caused by the diffuse reflection of the diffuse reflector, the light rays are diffused by being diffused by the uneven surface of the cured film surface. The amount of light diffused from the film surface is increased even at a position far from the light source, which has the effect of providing a reflective light-receiving element with excellent diffusion effect (brightness). In addition, the cured film containing the hydrolyzable organometallic compound protects the polarizing plate that constitutes the reflective light-receiving element, and also has excellent adhesion to the polarizing plate, abrasion resistance, chemical resistance, etc. Therefore, the initial quality characteristics of the reflective light-receiving element can be maintained for a long period of time, and there is also the effect that a reflective light-receiving element with excellent reliability can be provided.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional configuration diagram of a reflective liquid crystal display element, a diffuse reflection plate, and a miniature light bulb, and FIG. 2 is a plan configuration diagram. 1... Reflective liquid crystal element, 2... Diffuse reflector, 3
...Miniature light bulbs, 4, 5, 6, 7, 8... Brightness measurement locations. Figure 3 shows the glossiness at the acceptance angle at an incident angle of 45°. Figure 4 shows the glossiness at the acceptance angle at an incident angle of 60°. 9, 11... Reflective liquid crystal element A, 1 of the present invention
0, 12...Conventional reflective liquid crystal element B. Figure 5 shows the relationship between measurement location and brightness using a miniature light bulb light source. 13
... Reflective liquid crystal display element A of the present invention, 14... Conventional reflective liquid crystal display element B.

Claims (1)

[Claims] 1. In a reflective light-receiving element installed above with a diffuse reflector and an air layer interposed therebetween, at least one cellulose resin and at least one hydrolyzable organometallic compound are placed on the bottom surface of the reflective light-receiving element. A reflective light-receiving element characterized by being coated with a cured film of a mixture of