JPH08320407A - Lens sheet, diffusion panel and transmission type screen - Google Patents

Abstract

PURPOSE: To provide a bright and sharp image with little reflection of external light by forming an anti-reflection film of thickness different from an optical interference theory on a lens sheet member provided with a definite or indefinite shape. CONSTITUTION: An anti-reflection film 5 is provided on the front surface of a lenticular lens 4 with a prescribed thickness. The anti-reflection film 5 is composed of by applying a member having refractive index lower than that of a material composing a lenticular lens sheet 7, e.g. a resin member made of polymer on the surface so that the film thickness becomes 2λ/4n-5λ/4n. Consequently, a lens sheet for a transmission type screen or a diffusion panel exhibits the anti-reflection effect larger than before. Namely, the anti-reflection effect is larger compared with the film thickness based on the optical interference theory, the performance of high transmissivity is obtained and they are easily and cheaply worked/produced by means of a conventional device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens sheet provided with an antireflection coating having a predetermined film thickness and a diffusing panel for a liquid crystal device. More specifically, the present invention relates to a lenticular lens sheet which constitutes a transmission screen of a projection television receiver. Fresnel lens sheet, diffuser panel, etc.

[0002]

2. Description of the Related Art Conventionally, transmission type screens and liquid crystal panels
If the anti-reflection coating has a predetermined thickness, a transmission screen
High refractive index with a lower refractive index than that of the base material for LCDs and LCD panels
Implemented based on the theory of optical interference (λ / 4n) using a child material
Was. Figure 8 shows the basic theory of anti-reflection film by optical interference.
Show. Let the refractive index of the flat substrate 107 be n ₂, Bending of thin film 106
Folding factor is n, and incident light medium (air in most cases)
The refractive index of n₁Is defined. Vertically incident light 100 is air 1
Reflection of the thin film 106 that occurs at the interface between 05 and the thin film 106
Intensity 103 of light reflected from the upper surface by 101 and thin film 106
Lower surface reflection 10 of the thin film 106 occurring at the interface of the surface substrate 107
The intensity 104 of the light reflected from the bottom surface due to 2 completely cancels each other out.
Includes the intensity 103 of the upper surface reflected light and the intensity 10 of the lower surface reflected light.
The intensities of 4 must be equal. For this each
The indices of refraction at the interface are equal. That is, n₁/ N =
n / n₂(N²= N₁× n₂) Must be satisfied
There is. From this relational expression, the refractive index n of the antireflection film is
Air n that can be regarded as ordinary refractive index 1₁And substrate refractive index n₂Between
Value of, (n²= 1 × n₂That is n²= N₂Next),
Refractive index n of plate₂Is the square root of. In addition, the incident light 10
Part of 0 is reflected on the upper and lower surfaces of the antireflection film.
However, both reflections are in a medium with a lower refractive index than the adjacent medium.
Occurs. Therefore, in the interference effect that the two reflected light beams cancel each other out,
To make the relative phase shift 180 degrees,
The total phase difference between the two light beams is 1/4 wavelength
The optical thinness of the film when it corresponds to 2 times, that is, 180 °
It suffices if the film has a film thickness of 1/4 wavelength (Equation 1).
Yes. Film thickness (d) = (λ × 1) / (4 × n) (Equation 1) From these, the simplest antireflection film is the substrate refraction.
Has a refractive index equal to the square root of the index, and its optical thin film
Single layer film having a value equal to 1/4 of the wavelength of light when used
Becomes However, as an existing thin film material, substrate refraction
Since no material has an index of refraction equal to the square root of the index,
Also selects and uses a material having a refractive index close to the theoretical value.
According to the light interference theory (λ / 4n)
Examples of the conventional examples are Japanese Patent Laid-Open No. 5-265095 and Japanese Patent Laid-Open No.
Japanese Patent Application Laid-Open No. 5-289176 and Japanese Patent Application Laid-Open No. 5-289179
The proposal is known. In all of these examples, optical interference
When the film thickness of the film is formed based on the theoretical film thickness (λ / 4n)
Of. For example, in JP-A-5-265095,
Film of low refractive index resin film formed on the surface of lens sheet
The center of thickness should be 12 so that the relation of (Equation 1) above is satisfied.
It is limited to the range of 5 nm to 150 nm.

Further, in JP-A-5-289176 and JP-A-5-289179, the film thickness of the low refractive index resin film formed on the surface of the lens sheet is the theoretical film thickness of optical interference (λ / 4).
It is based on n).

[0004]

However, the Fresnel lens sheet and the lenticular lens sheet constituting the above-mentioned conventional transmission screen have a plurality of lenses arranged on the surface thereof.

For example, in the case of the lenticular lens shown in FIG. 1, it is only the central portion of the lenticular lens that the strongest vertically incident light vertically passes through the antireflection coating on the surface of the lenticular lens. Becomes

The film thickness (λ
/ 4n) when the antireflection film is formed, the light beam that actually transmits the film thickness d based on the optical interference theory is only the central part of the lenticular lens, and the other lenticular lens surface is different from the optical interference theory. The light is transmitted through the thicknesses d1 and d2.

As a result, it has been found that the amount of transmitted light having a film thickness according to the theory of light interference is extremely small and a sufficient antireflection effect cannot be obtained.

Also, in the case of the Fresnel lens shown in FIG. 6, similarly to the reflection of light on the plane plate, the vertically incident light ray does not become the transmitted light of the film thickness d according to the light interference theory, which is different from the light interference theory. The amount of transmitted light having a film thickness d3 becomes very large.

As a result, the film thickness (λ / 4n) according to the light interference theory on the plane plate is not established, the effect of the low reflection resin coating is different from the light interference theory, and a sufficient antireflection effect cannot be obtained. was there.

In view of the above problems, it is an object of the present invention to provide a lens sheet for a transmissive screen, a diffusion panel, or the like, which has a coating size excellent in antireflection effect and is not based on the theory of light interference.

[0011]

In order to solve the above problems, the present invention solves the above problems by forming a low refractive index member such as a high refractive index member on the surface of a Fresnel lens sheet or a lenticular lens sheet having a plurality of lenses or an uneven diffusion panel. A resin member made of molecules is arranged to have a predetermined thickness.

The thickness of the antireflection coating applied to the lens sheet member is different from that of the theory of light interference.

[0013]

With the above-mentioned structure, the present invention can exert an antireflection effect which has not been obtained in the past in a lens sheet for a transmission type screen or a diffusion panel. That is, the antireflection effect is greater than the film thickness dimension based on the light interference theory, and the performance with high transmittance can be obtained. Further, it can be easily and inexpensively processed and produced by the conventional device.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A lens sheet according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view of the essential parts of a lenticular lens sheet according to an embodiment of the present invention. In FIG. 1, an antireflection coating 5 is provided on the surface of the lenticular lens 4 to have a predetermined film thickness.
The antireflection coating is a member having a refractive index lower than that of the material forming the lenticular lens sheet 7, for example, a resin member made of a polymer and having a film thickness of 1.2λ / 4n to 5λ / 4n.
It is applied so that

FIG. 2 is a measured reflectance curve obtained by actually measuring reflectance in the visible light region having different thicknesses by forming an antireflection coating of low refractive index resin on the lenticular lens sheet of FIG. 1 with various thicknesses. Indicates. FIG. 3 shows the reflectance curve 55 of FIG.
The reflectance effect curve which shows the difference of the reflectance with the film thickness of an antireflection coating in the wavelength of 0 nm is shown. FIG. 4 shows reflectance curves in the visible light region when the low refractive index resin is used and various thicknesses are formed according to theoretical calculation. FIG. 5 shows measured reflectance curves in the visible light region when the antireflection coating of the low refractive index resin is formed in various thicknesses on the flat substrate.
FIG. 6 shows a cross-sectional view of the essential parts of an antireflection coating of the present invention in which a Fresnel lens sheet is formed of a low refractive index resin with an optimum film thickness.

As shown in FIG. 1, when the antireflection coating 5 is formed on the surface of the lenticular lens 4, the vertically incident light 1 becomes transmitted light 2 and reflected light 3. At this time, the reflected light 3 uses a member having a refractive index lower than that of the lenticular lens sheet due to the antireflection coating 5, and becomes a very low reflected light due to the optical interference effect. Conventionally, the optimum film thickness dimension of the antireflection coating due to the light interference effect has been set to the film thickness (λ / 4n) according to the light interference theory in the plane plate.

However, in the lenticular lens sheet, the film thickness (λ / 4n) according to the theory of light interference is not always the optimum film thickness. The optimum film thickness of the antireflection thin film when the surface has a regular or irregular shape will be described below. In FIG. 1, on the surface of the lenticular lens 4,
For example, when an antireflection thin film is formed with a film thickness (λ / 4n) according to the theory of light interference, an incident light ray A incident on the central portion of the lenticular lens of the vertically incident light 1 and an incident light ray E incident on the flat portion of the black stripe 6 Only the transmitted light is transmitted through the theoretical optical interference film thickness d that matches the theory. The incident light of B and C incident on the lens-shaped portion does not become the transmitted light that transmits the film thickness according to the theory of optical interference, but actually transmits the film diagonally.

As a result, the film thickness d1, which is different from the optical interference theory,
The light is transmitted through the area of d2, and the maximum antireflection effect cannot be obtained.

The present invention obtains an optimum antireflection effect by forming an antireflection film having a film thickness dimension different from the theory of optical interference. The film thickness dimension will be described below. FIG. 4 shows reflectance curves in the visible light region when the antireflection coating of the low refractive index resin used in the present invention is formed into various film thickness dimensions by a theoretical calculation formula. The plane substrate reflectance curve F0 of the acrylic resin is in the visible wavelength region (400 nm to 700 n
The reflectance curve of about 3.9% is almost uniform in m).
Further, the thickness of the antireflection coating is 0.05 μm (F1)
~ 0.07 μm (F2) ~ 0.1 μm (F) ~ 0.12
5 μm (F3) to 0.15 μm (F4) to 0.21 μm
When changed from (F5) to 0.25 μm (F6), the theoretical calculated film thickness of 0.1 μm (F) shows the lowest reflectance in the entire visible wavelength region. FIG. 5 shows the reflectance characteristics when the low-refractive index resin in the constitution of the present invention is formed on a flat substrate with various film thickness dimensions.

That is, the reflectance curve G0 of the flat substrate of acrylic resin, the film thickness formed on the flat substrate hereinafter is 0.05 μm.
(G1) to 0.07 μm (G2) to 0.125 μm (G
3) to 0.15 μm (G4) to 0.21 μm (G5)
It is 0.25 μm (G6), which is a reflectance curve almost similar to the theory. The optimum theoretical film thickness λ / 4n is 0.550 ÷
(4 × 1.34 = 0.1026 μm, and F,
This is indicated by G in FIG.

However, in the case of a lenticular lens sheet having a regular or irregular lenticular lens on the surface, the film thickness (λ / 4n) according to the theory of optical interference as described above.
Is not the optimum film thickness. In a lenticular lens with a reflectance of χ0, the thickness of the antireflection coating is 0.05μ
m (χ1) to 0.07 μm (χ2) to 0.1 μm (χ)
~ 0.125 µm (χ3) ~ 0.15 µm (χ4) ~
FIG. 2 shows the reflectance characteristics when changing from 0.21 μm (χ5) to 0.25 μm (χ6). The optimum film thickness dimension in the measured value is 1. of the optimum film thickness dimension in the optical interference theory.
It became 2 to 3 times. FIG. 3 shows the reflectance characteristic of the central wavelength of 550 nm in the visible wavelength region, and the antireflection effect curve y does not show a large change when approaching the predetermined film thickness.

Various lens performances (lens condensing characteristics,
As a result of measuring and evaluating light diffusion characteristics, other brightness unevenness, color unevenness, color change, etc., it was found that the lens performance did not deteriorate when the film thickness dimension of the antireflection coating in the present invention was 2 μm or less. That is, the effective film thickness dimension of the antireflection coating in the present invention is about 20 times the film thickness dimension in the theory of optical interference. However, it goes without saying that the optimum film thickness dimension also depends on the manufacturing cost and quality stability.

In the case of this embodiment, the desired film thickness dimension range was set to 0.12 μm to 0.50 μm. However, the present invention is an example in which the lenticular lens sheet material uses an acrylic resin (refractive index 1.49) and an antireflection coating material (refractive index 1.34), and the substrate material is a polycarbonate resin (refractive index 1.59). And MS resin (refractive index 1.53 to 1.5
7) In addition, when the material (refractive index) of the antireflection film is different from the material of different refractive index, the range of the optimum film thickness dimension by various combinations is important. Therefore, in the present invention, the desirable film thickness dimension range is 1.2λ / 4n to
It is set to 5λ / 4n.

Even in a Fresnel lens sheet or a diffusion panel, an antireflection coating is used in the range of 1.2λ / 4n to 5λ / 4n.
It is effective to apply in the range of the film thickness dimension. The reason for this is that, as shown in FIG. 6, even in the Fresnel lens sheet, there is a large amount of obliquely transmitted light 11. As a result, reflection occurs at a film thickness d3 different from the optical interference theory, and the optical interference theory film thickness does not hold. The same applies to the diffusion panel.

Next, the transmissive screen according to the embodiment of the present invention will be described. FIG. 7 shows a cross-sectional view of the essential parts of a transmissive screen according to an embodiment of the present invention. In this case, the transmissive screen is composed of two lenticular lens sheets and Fresnel lens sheets. Further, an antireflection coating 27 is provided on the surfaces of the incident light side lens 24, the outgoing light side lens 25 and the black stripe 23 so as to have a predetermined film thickness.

In this case, the thickness of the antireflection coating 27 is 1.2 λ / 4n to 5λ / 4n. The application method may be any method such as dipping method, spraying method,
A vapor deposition method or the like may be used. The dipping method was used in the examples of the present invention.

Further, as a member constituting the antireflection coating, "CYTOP (refractive index n = 1.3) manufactured by Asahi Glass Co., Ltd.
4) ”(trade name) is used. The film thickness dimension depends on the concentration of Cytop and the pulling rate from the dip tank.
In the embodiment of the present invention, the film thickness is 1.2λ / 4.
0.12 μm to 0.5 μm in the range of n to 5λ / 4n
0.2 μm ± 0.05 μ
formed to m.

Generally, in a transmissive screen, C
An incident light ray 28 from RT enters the Fresnel lens sheet 21, becomes a parallel light ray by the Fresnel lens 26, and enters the incident side lens 24 of the lenticular lens sheet 22 and is condensed near the surface of the emitting side lens 25. The emitted light ray 29 reaches the observer. At this time, the entrance side lens 24 and the exit side lens 25 of the lenticular lens sheet 22
A reflected ray 32 occurs at the surface of the. In order to reduce the reflected light, the antireflection coating 27 is provided with the lenticular lens sheet 2
It is formed on the surfaces of the second incident side lens 24 and the outgoing side lens 25. While the reflectance of the lenticular lens sheet 22 at a visible wavelength of 550 nm is 4.5% (point χ0 in FIG. 3, no antireflection coating), an antireflection coating is formed with a film thickness dimension based on the conventional theory of optical interference. If you do 3.6
% (Χ in FIG. 3), the reflectance of the dimension of the antireflection coating based on the constitution of the present invention is 3.1% (χ5 in FIG. 3) which is lower.

That is, the characteristic is about 16% as compared with the conventional method.
(3.6 / 3.1) is improved, and the light transmittance is increased.
As a result, when the incident light ray 28 of the CRT becomes the outgoing light ray 29, it is improved by about 16%, and the brightness of the screen performance is improved.

Further, when the incident light ray 30 of the external light is incident, the reflected light ray 31 of the external light is generated, but the effect of the antireflection coating of the present invention is the same in the reflection of the external light.
That is, the contrast of external light was improved by 16% in the screen performance.

In this embodiment, an example of forming the antireflection coating of the present invention on the lenticular lens sheet has been described, but the antireflection coating of the present invention may be formed on the Fresnel lens sheet. Of course, the antireflection coating may be formed on both the lenticular lens sheet and the Fresnel lens sheet. When the antireflection coating is formed on both of them, the screen characteristics can be further improved.

Furthermore, in addition to the lenticular lens sheet and the Fresnel lens sheet, a transmissive screen having a diffusion panel on the front surface of the lenticular lens sheet may also be used. The combination of the configurations in which the antireflection coating is provided on each lens sheet may be arbitrarily implemented.

In this embodiment, an example in which the screen of the projection type television receiver using a fixed lens is used is described. However, the structure of the present invention has an irregular lens group or an uneven surface. It goes without saying that it is also effective when

[0034]

As described above, by forming an antireflection coating on a lens sheet member having a regular shape or an irregular shape or a diffusion panel having unevenness to have a film thickness different from the optical interference theory, An antireflection effect with better performance can be obtained than in the case of an antireflection coating formed with a film thickness based on the theory of light interference.

As a result, when it is used for a screen of a projection television receiver, a liquid crystal panel, other filters, a diffusion plate, etc., a clear image with little brightness and external light reflection can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part of a lenticular lens sheet according to an embodiment of the present invention.

FIG. 2 is a characteristic diagram showing the relationship between the film thickness and the reflectance of the antireflection coating in the constitution of the present invention.

FIG. 3 is a curve diagram of an antireflection effect at a visible wavelength of 550 nm in the constitution of the present invention.

FIG. 4 is a reflectance curve diagram of theoretical values when an antireflection coating film is formed on a flat plate.

FIG. 5 is a reflectance curve diagram of actual measurement values when an antireflection film thickness is formed on a flat plate.

FIG. 6 is a cross-sectional view of essential parts of a Fresnel lens sheet according to an embodiment of the present invention.

FIG. 7 is a cross-sectional view of a main part of a transmissive screen according to an embodiment of the present invention.

FIG. 8 is a sectional view of an essential part for explaining the behavior of light rays when an antireflection coating based on the theory of light interference is formed on a flat plate.

[Explanation of symbols]

1 Vertical Incident Light 2 Transmitted Light 3 Reflected Light 4 Lenticular Lens 5 Anti-Reflection Coating 6 Black Stripe 7 Lenticular Lens Sheet 10 Vertical Incident Light 11 Transmitted Light 21 Fresnel Lens Sheet 22 Lenticular Lens Sheet 23 Black Stripe 24 Incident Side Lens 25 Outgoing Side Lens 26 Fresnel lens 27 Antireflection coating 28 Incident light from CRT 29 Emission light 30 External light incident light 31 External light reflected light 32 CRT light incident light reflected light 100 Normal incident light 101 Thin film top surface reflection 102 Thin film bottom surface Reflection 103 Intensity of light reflected from upper surface of thin film 104 Intensity of light reflected from lower surface of thin film 105 Incident light side medium (usually air) 106 Thin film 107 Flat substrate d Optical interference theory film thickness d1 Film thickness different from optical interference theory d2 Optical interference theory Different film thickness d3 Interference theory and different thicknesses χ0 thickness was formed on the reflectance χ1 lenticular lens of the optical interference theory thickness 0.1μm was formed on the measured reflectance χ lenticular lens of the lenticular lens 0.05μ
m reflectance χ2 film thickness formed on lenticular lens 0.07μ
m reflectance χ3 film thickness 0.125 formed on lenticular lens
μm reflectance χ4 Film thickness 0.15μ formed on lenticular lens
m reflectance χ5 film thickness 0.21μ formed on lenticular lens
m reflectance χ6 film thickness formed on lenticular lens 0.25μ
m reflectance χ7 film thickness 0.30μ formed on lenticular lens
Reflectivity of m y Antireflection effect curve due to reflectance of 550 nm in the central portion of visible wavelength F0 Reflectance of flat substrate of acrylic resin F Theoretical calculation Reflectance of 0.1 μm film thickness F1 Theoretical calculation Reflectance of 0.05 μm film thickness F2 Theory Calculated film thickness 0.07 μm reflectance F3 Theoretical calculated film thickness 0.125 μm reflectance F4 Theoretical calculated film thickness 0.150 μm reflectance F5 Theoretical calculated film thickness 0.21 μm reflectance F6 Theoretical calculated film thickness 0.25 μm Reflectance G0 Actually measured reflectance of acrylic resin flat substrate G Theoretical film thickness 0.1 μ formed on acrylic resin flat substrate
Measured reflectance of m G1 Thickness of film formed on acrylic resin flat substrate 0.05μ
Measured reflectance of m G2 0.07μ film thickness formed on acrylic resin flat substrate
m actually measured reflectance G3 film thickness 0.125 formed on acrylic resin flat substrate
Measured reflectance of μm G4 0.15μ film thickness formed on acrylic resin flat substrate
m actually measured reflectance G5 film thickness 0.21μ formed on acrylic resin flat substrate
Measured reflectance of m G6 Film thickness formed on acrylic resin flat substrate 0.25μ
Actual reflectance of m

Claims (17)

[Claims] 1. A member having a refractive index lower than that of a material forming the sheet is arranged on the surface of a sheet having lenses or irregularities in a film thickness different from the optical interference theoretical thin film λ / 4n to prevent reflection. A lens sheet having a film formed thereon. 2. The lens sheet according to claim 1, wherein the antireflection coating is a polymer material. 3. The thickness dimension of the antireflection coating is 1.2λ / 4.
The range from n to 5λ / 4n is set.
The lens sheet described. 4. The surface of the lenticular lens sheet,
A lenticular lens sheet, characterized in that an antireflection coating is formed by arranging a member having a refractive index lower than that of the material forming the lenticular lens sheet in a film thickness dimension different from the optical interference theoretical thin film λ / 4n. 5. The lenticular lens sheet according to claim 4, wherein the antireflection coating is a polymer material. 6. The thickness dimension of the antireflection coating is 1.2λ / 4.
6. A range from n to 5λ / 4n is set.
Lenticular lens sheet described. 7. An antireflection coating is formed on the surface of a Fresnel lens sheet by arranging a member having a refractive index lower than that of the material forming the Fresnel lens sheet in a film thickness different from the theoretical thin film of optical interference λ / 4n. Fresnel lens sheet characterized by doing. 8. The Fresnel lens sheet according to claim 7, wherein the antireflection coating is made of a polymer material. 9. The thickness dimension of the antireflection coating is 1.2λ / 4.
The range from n to 5λ / 4n is set.
Fresnel lens sheet described. 10. An optical interference theory thin film λ / 4n is provided on the surface of a substrate with a member having a refractive index lower than that of a material forming the substrate.
A diffusion panel characterized in that the antireflection coating is formed by arranging it in a different film thickness dimension. 11. The diffusion panel according to claim 10, wherein the antireflection coating is made of a polymer material. 12. The film thickness dimension of the antireflection coating is 1.2λ /
The diffusion panel according to claim 11, wherein the diffusion panel has a range of 4n to 5λ / 4n. 13. A transmissive screen comprising the lenticular lens sheet according to claim 4 and a Fresnel lens sheet. 14. A transmissive screen comprising the lenticular lens sheet according to claim 4 and the Fresnel lens sheet according to claim 7. 15. A transmissive screen comprising the diffusion panel according to claim 10, a lenticular lens sheet, and a Fresnel lens sheet. 16. An optical interference theory thin film λ / 4n is provided on the surface of a substrate with a member having a refractive index lower than that of a material forming the substrate.
A light diffusion theoretical thin film λ / 4n is provided on the surface of the lenticular lens sheet having a refractive index lower than that of the material forming the lenticular lens sheet, and a diffusion panel having an antireflection coating formed in a different film thickness. A transmissive screen comprising: a lenticular lens sheet having an antireflection coating formed in a film thickness different from the above, and a Fresnel lens sheet. 17. A light interference theoretical thin film λ / 4n provided on the surface of a substrate with a member having a refractive index lower than that of a material forming the substrate.
A light diffusion theoretical thin film λ / 4n is provided on the surface of the lenticular lens sheet having a refractive index lower than that of the material forming the lenticular lens sheet, and a diffusion panel having an antireflection coating formed in a different film thickness. A lenticular lens sheet provided with an antireflection coating and having a different film thickness, and a member having a refractive index lower than that of the material forming the Fresnel lens sheet on the surface of the Fresnel lens sheet. A transmissive screen comprising: a Fresnel lens sheet having a film thickness different from 4n and having an antireflection coating formed thereon.