JPH0943587A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid the concentration of light for irradiation to a liquid crystal layer and to avert the exertion of an adverse influence on liquid crystals without attaining a high temp. by specifying the relation between the thickness of the glass substrate on a liquid crystal layer side of glass substrates constituting flat plate type microlenses and a focal length to an adequate relation. SOLUTION: This liquid crystal display device is provided with the liquid crystal layer 4 between a pair of translucent panels 2, 3. Light opaque parts 6 and pixel apertures 7 to be transmitted with light are formed on one surface side of the liquid crystal layer 4. The translucent panel 2 is constituted by joining two sheets of the glass substrates 8, 9. Many recessed parts 10 are regularly formed on the joint surface of two sheets of the glass substrates 8, 9. A high-refractive index material is packed into these recessed parts 10, by which planoconvex lenses 11 are formed. These lenses are so formed as to satisfy 0.6/t<=(1/r)(n2 -n1 )/n3 <1/t when the refractive index of the glass substrate 8 is defined as n1 , the refractive index of the high-refractive index material as n2 , the refractive index of the glass substrate 9 as n3 , the radius of curvature of the recessed parts 10 as (r) and the thickness of the glass substrate 9 as (t).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, a part of which is a flat plate type microlens formed by filling a recess formed in a glass substrate with a transparent resin having a high refractive index.

[0002]

2. Description of the Related Art A projector television (PTV) using a transmissive liquid crystal display device has been put into practical use. As shown in FIG. 4, the projector television has a schematic configuration in which the liquid crystal display device 100 is arranged between an irradiation light source and a condenser lens 101, and light transmitted through the liquid crystal display device 100 is condensed by the condenser lens 101 and the projection lens 102.
It is designed to be projected on a screen such as a wall via.
There is also a structure in which the liquid crystal display device 100 is arranged on the right side of the condenser lens 101 in FIG.

A conventional liquid crystal display device 100 holds a liquid crystal layer 105 between two transparent panels 103 and 104, and about 50 to 70% of the liquid crystal layer 105 is wiring, TFT (thin film transistor), black matrix, or the like. The remaining 50 to 30% is a pixel opening portion 105a through which the irradiation light is transmitted.

In the conventional PTV, about 50 to 70% of the parallel irradiation light is blocked from passing through the liquid crystal layer 105, so that the screen becomes dark. On the other hand, when the intensity of the irradiation light is increased to make the screen brighter, the temperature rises, which adversely affects the liquid crystal layer.

Therefore, Japanese Patent Application Laid-Open No. 3-214101,
JP-A-3-214121, JP-A-4-50817
Japanese Patent Laid-Open No. 5-346577 and the like propose proposals for eliminating the above disadvantages by using a flat plate type microlens. As shown in FIG. 5, one of the two transparent panels constituting the liquid crystal display device 100 is one of the panels 103 and two glass substrates 103a.
103b, at least one of the two glass substrates is used as a flat plate type microlens 106, and the irradiation light is focused on the pixel opening 105a.
The screen is prevented from becoming dark by passing through 05a.

[0006]

As described above, the liquid crystal display device in which the flat plate type microlens 106 is incorporated in a part thereof is designed so that the focus of the lens coincides with the pixel opening 105a. However, if the irradiation light is condensed at one point of the pixel opening, the condensed point becomes a high temperature, which adversely affects the liquid crystal layer.

If the focus of the flat plate type microlens 106 is set on the liquid crystal surface, the diameter of the projection lens is increased and the cost is increased. That is, the FNo. Of the lens is defined by (focal length in air / maximum lens diameter), and if the focus of the flat microlens is set on the liquid crystal surface, the focal length becomes shorter, so the FNo. It becomes smaller, and the FNo. Of the projection lens must be reduced corresponding to the FNo. Of the flat plate type microlens, and as a result, the aperture of the projection lens must be increased.

Of the substrates constituting the flat plate type microlens, if the thickness of the substrate on the liquid crystal layer side is increased and the focal point is set on the liquid crystal surface, the FNo. Of the flat plate type microlens increases. Irradiation light is not perfectly parallel but 3-6
There is also irradiation light that is incident while tilted. Assuming such irradiation light that is not parallel light, when the thickness of the substrate on the liquid crystal layer side is increased and the focus is set on the liquid crystal surface, the deviation of the irradiation light on the liquid crystal surface becomes large, and most of the irradiation light is The part is separated from the pixel opening, and the amount of light transmitted through the pixel opening is reduced.

Therefore, it is conceivable to shift the focus from the position of the pixel opening. However, when the focus position is shifted to the irradiation light source side (left side in FIG. 5) with respect to the pixel aperture, the spread angle θ of the light becomes large, so that the diameters of the condenser lens and the projection lens must be further increased. On the contrary, when the light is diverged toward the condenser lens side (right side in FIG. 5), the spread angle θ of the light becomes small, but if it is shifted too much, a part of the irradiation light impinges on the light opaque portion.

[0010]

According to the present invention, the refractive index of a glass substrate constituting a flat plate type microlens incorporated in a liquid crystal display device, the refractive index of a high refractive index material to be a lens, and a high refractive index material are filled. This is done by focusing on the relationship between the radius of curvature of the concave portion, the thickness of the glass substrate on the liquid crystal layer side of the glass substrates forming the flat plate type microlens, and the focal length.

That is, in a liquid crystal display device in which a liquid crystal layer is provided between a pair of translucent panels, two translucent panels on the side of the pair of translucent panels on which irradiation light enters are made of two glass plates. The substrates are bonded together, and a large number of concave portions are regularly formed on the bonding surface of one of the two glass substrates with the other glass substrate, and the concave portions are filled with a high refractive index material. In the case of a liquid crystal display device in which a plano-convex lens is used as the plano-convex lens, the refractive index of _one glass substrate on which the plano-convex lens is formed is n ₁ , the refractive index of the high-refractive-index material to be the plano-convex lens is n ₂ , and the other glass substrate is formed. If the refractive index is n ₃ , the radius of curvature of the concave portion filled with the high refractive index material is r, the thickness of the glass substrate on the liquid crystal layer side of the two glass substrates is t, and the focal length is f, then 1
/ F = represented by _{(1 / r) (n 2} -n 1) / n 3. Since the focus is located on the liquid crystal surface when f = t, f> t must be satisfied as described above. Even if f> t, the irradiation is performed if the focus position is too far from the liquid crystal surface. Part of the light falls on the opaque part of the light.
As a result of the experiment, it was found out that the efficient irradiation is up to 0.6f = t. Therefore, 0.6 / t ≦
(1 / r) (n ₂ −n ₁ ) / n ₃ <1 / t.

Further, as shown in FIG. 6, the irradiation light focused by the plano-convex lens 106 of the flat plate type micro lens is the liquid crystal layer 10.
After passing through 5, the light enters the projection lens 102 as divergent light, but the FNo. (F / n ₃ · p) of the plano-convex lens 106 is larger than the FNo. (F ₀ / p ₀ ) of the projection lens 102. In that case, the diverging light will be eclipsed by the projection lens. Here, although the condenser lens is omitted in FIG. 6, the above relationship holds even when there is a condenser lens. Further, the FNo. Of the plano-convex lens 106 is set to f / n3 · p in order to convert it to the focal length in the air, and p is the longest distance between the centers of mutually adjacent concave portions arranged densely. Say. For example, in the case as shown in FIG. 7, there are two types of center-to-center distances of the concave portions, but the longer distance is indicated.

Then, p (1 / r) (n ₂ −n ₁ ) represents the reciprocal of the FNo. Of the plano-convex lens, while the FNo. Of the projection lens is between 1.8 and 8. That is, FNo. =
A lens of 1.8 or less is difficult to manufacture, and FNo. = 8 or more means that the NA is small, and the light-collecting effect is insufficient. In summary, the plano-convex lens FNo. Is the projection lens FN.
smaller than o., the FNo. of the projection lens is between 1.8 and 8, and the reciprocal of the FNo. of the plano-convex lens is p (1 / r)
Since (n ₂ −n ₁ ), 1/8 ≦ p (1 / r) (n ₂
It is preferable that the relational expression expressed by −n ₁ ) ≦ 1 / 1.8 is satisfied.

8 to 13 show a procedure for forming a flat plate type microlens, of which FIG. 12 is shown in FIG.
FIG. 13 is a plan view of FIG. First, FIG.
As shown in FIG. 3, Cr or the like is deposited on one surface of the glass substrate to form a film, and the Cr film is patterned (opened) to serve as a mask. The glass substrate is immersed in an etchant such as hydrofluoric acid for etching. Then, the etchant enters from the hole of the mask and isotropic etching is performed to form a substantially hemispherical recess.

Here, if etching is attempted until the shape of the recess becomes close to a hemisphere, the area of the portion supporting the mask becomes small, and the Cr film is cracked and uniform spherical etching cannot be performed. Precipitation of metal fluoride, which is a product of etching, is deposited in the recesses, and the etched surface becomes rough. The etching depth without causing such a disadvantage was 60 μm or less.

Further, as shown in FIG. 9, after forming a substantially hemispherical recess by etching, the Cr film is removed, and further the products produced during the etching are removed. After this, as shown in FIG. 10, etching is performed again, and as shown in FIG. 11, the concave portion is filled with a high refractive index material to form a lens portion.
By the second etching described above, the surface of the glass substrate is uniformly etched, and as shown in FIG. 12, the supporting portion having a triangular shape in plan view disappears, and the dense state shown in FIG. 13 is obtained. The radius of curvature of the substantially hemispherical recess becomes large.

By the way, if the depth of the recess is h,
^{h = r- (r 2 -p 2} /4) is ^1/2. And because in the second etching as described above is the etching with a uniform thickness is ^{made, h = r- (r 2 -p} 2/4)
^It is preferable that ^1/2 ≦ 60 μm.

When the concave portion (lens) is a complete hemisphere, that is, when h = 0.5p, the angle of incidence on the lens surface becomes too large, reflection at the boundary surface becomes large, and spherical aberration occurs. Becomes larger, and the light condensed at the opening of the liquid crystal layer decreases. Such in order to eliminate the ^{disadvantage, h = r- (r 2 -p} 2/4) preferably set to ^1/2 ≦ ^0.45p.

The above conditions also apply when a biconvex lens is formed as a flat plate type microlens. That is, in a liquid crystal display device in which a liquid crystal layer is provided between a pair of translucent panels, one of the pair of translucent panels on the side on which the irradiation light is incident is joined to two glass substrates. In the case of a liquid crystal display device in which concave portions corresponding to each other are regularly formed on the bonding surface of these two glass substrates and these concave portions are filled with a high refractive index material to form a biconvex lens, The refractive index of the glass substrate is n1, the refractive index of the high-refractive-index material to be a biconvex lens is n2, the radius of curvature of the concave portion formed in one of the two glass substrates is r1, and the two When the radius of curvature of the concave portion formed in the other glass substrate of the glass substrates is r2 and the thickness of the glass substrate on the liquid crystal layer side of the two glass substrates is t, 1 / f
= (1 / r ₁ + 1 / r ₂ ) (n ₂ −n ₁ ) / n ₃ Therefore, for the same reason as above, 0.6 / t
≦ (1 / r ₁ + 1 / r ₂ ) (n ₂ −n ₁ ) / n ₁ <1 / t.

Also, in the case of a biconvex lens, from the relationship between the FNo. And the FNo. Of the projection lens, 1 / 8≤p (1 / r ₁ +
It is preferable that 1 / r ₂ ) (n ₂ −n ₁ ) ≦ 1 / 1.8 is satisfied.

Further, in the case of the double-convex lens, the relationship between the etching ^{_{depth, r 1 - (r 1 2}} -p 2/4) 1/2 ≦ 60μ
m and ^{_{r 2 - (r 2 2 -p}} 2/4) is preferably satisfied ^1/2 ≦ 60 [mu] m.

Furthermore, in the case of the double-convex lens, the relationship between the longest distance p between the centers of the ^{_{recess, r 1 - (r 1 2}} -p 2/4)
^1/2 ≦ ^0.45p and ^{_{r 2 - (r 2 2 -p}} 2/4) 1/2 ≦ 0.
It is preferable to satisfy the relationship of 45p.

[0023]

Embodiments of the present invention will be described below with reference to the accompanying drawings. Here, FIG. 1 shows a projector television (P) incorporating the liquid crystal display device according to the present invention.
2 is an enlarged cross-sectional view of the liquid crystal display device, and a projector television (PTV) uses the liquid crystal display device 1 according to the present invention as an irradiation light source and a condenser lens 21.
The light transmitted through the liquid crystal display device 1 is projected on the screen such as a wall through the condenser lens 21 and the projection lens 22.

The liquid crystal display device 1 comprises a pair of translucent panels 2,
The liquid crystal layer 4 is provided between the two. A transparent electrode 5 is provided on one surface side (incident side) of the liquid crystal layer 4, and a light non-transmissive portion 6 including wiring and TFTs and a pixel opening portion 7 through which light is transmitted are formed on the other surface side (emission side). Has been done.

On the other hand, the translucent panel 2 is constructed by joining two glass substrates 8 and 9 together.
A large number of concave portions 10 are regularly formed on the bonding surface of one glass substrate 8 of the other 9 and the other glass substrate 9, and the concave portions 10 are filled with a high refractive index material to form a plano-convex lens 11. There is.

Here, the materials, dimensions, characteristics (refractive index), etc. of the above-mentioned members are as follows. (Glass substrate 8) Material: Alkali-free glass (borosilicate glass) Thickness: 1.1 mm Refractive index n ₁ : 1.52 (recess 10) Longest distance between centers: 112 μm Depth: 40 μm Array: Delta array (hexagonal) Dense array) Arrangement pitch: 100 μm in X direction, 100 μm in Y direction Curvature radius r: 59.2 μm (lens 11) Material: Thermosetting resin Refractive index n ₂ : 1.66 (glass substrate 9) Material: Alkali-free glass (boro Silicate glass) Thickness: 400 μm Refractive index n ₃ : 1.52 (pixel aperture 7) Aperture size: □ 60 μm Ratio of aperture area to pixel area: 36% (transparent panel 3) Material: Alkali glass ( Corning Inc. # 7059) Thickness: 1.1 mm

In the above, the irradiation light incident on the plano-convex lens 11 is narrowed down to some extent, passes through the pixel opening 7, and is projected onto the screen such as a wall through the condenser lens 21 and the projection lens 22.

FIG. 3 is a sectional view showing another embodiment of the liquid crystal display device. In this liquid crystal display device, of the pair of translucent panels 40, 3 holding the liquid crystal layer 4, the translucent panel 3 is Same as the above, but the two glass substrates 41, 42 constituting the translucent panel 40 have concave portions 43, 44 corresponding to each other on their joint surfaces in a one-to-one manner.
4 is filled with a high refractive index material, and the glass substrates 41 and 42 are abutted and joined to each other, so that the concave portions 43 and 44 become the biconvex lens 45.

Here, the materials, dimensions, characteristics (refractive index), etc. of the above-mentioned members are as follows. (Glass substrate 41) Material: Alkali-free glass (borosilicate glass) Thickness: 1.1 mm Refractive index n ₁ : 1.52 (Glass substrate 42) Material: Alkali-free glass (borosilicate glass) Thickness: 500 μm Refractive index n ₁ : 1.52 (recess 43) Longest distance between centers: 112 μm Depth: 40 μm Radius of curvature r ₁ : 59.2 μm (recess 44) Longest distance between centers: 112 μm Depth: 40 μm Radius of curvature r ₂ : 59 .2 μm (lens 45) Material: Photocurable resin Refractive index n ₂ : 1.595

Since the liquid crystal layer and the transparent electrode are extremely thin, they are included in the thickness t of the glass substrate on the liquid crystal layer side in the description of the present invention.

Further, regarding the shape of the concave portion which becomes the lens portion of the flat plate type microlens, the contour shape is square, rectangular, regular hexagonal, hexagonal or strip-shaped (lenticular type) in the pixel opening of the liquid crystal layer in plan view. It can be selected according to the shape. In the lenticular type, the radius of curvature r is measured with reference to the cross section along the width direction of the band-shaped recess.

In the illustrated example, the resin is previously filled in the concave portions of the two glass substrates forming the flat plate type microlens, and the glass substrate is polished and laminated to have a smooth surface, and then the other glass substrate is used. Alternatively, the two glass substrates may be adhered at the same time as the filling, using a high refractive index resin as an adhesive.

[0032]

According to the present invention as described above,
The refractive index of the glass substrate that constitutes the flat plate type microlens incorporated in the liquid crystal display device, the refractive index of the high refractive index material that becomes the lens, the radius of curvature of the recess filled with the high refractive index material, and the flat plate type microlens Since the relationship between the thickness of the glass substrate on the liquid crystal layer side of the glass substrate and the focal length is made appropriate, the irradiation light is not concentrated on the liquid crystal layer and the temperature does not rise, so the liquid crystal is not affected by the liquid. Moreover, since most of the irradiation light passes through the pixel opening, the screen does not become dark.

That is, most of the irradiation light can be effectively used without shifting the focus of the flat plate type microlens from the liquid crystal surface to the side where the FNo. Further, even when the irradiation light is slightly inclined, the amount of light transmitted through the pixel opening is not reduced so much.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of a projector television incorporating a liquid crystal display device according to the present invention.

FIG. 2 is an enlarged sectional view of the liquid crystal display device.

FIG. 3 is a sectional view showing another embodiment of the liquid crystal display device.

FIG. 4 is a conceptual diagram of a conventional projector television.

FIG. 5 is a sectional view of a conventional example in which a flat plate type microlens is combined with a liquid crystal display device.

FIG. 6 is a diagram for explaining the relationship between the FNo. Of the convex lens and the FNo. Of the projection lens.

FIG. 7 is a conceptual diagram of a distance between centers of recesses.

FIG. 8 is an enlarged cross-sectional view showing a state where the Cr film is initially etched.

FIG. 9 is an enlarged sectional view showing a state after the first etching.

FIG. 10 is an enlarged cross-sectional view showing a state after the second etching.

FIG. 11 is an enlarged cross-sectional view showing a state in which a concave portion is filled with a high refractive index material.

FIG. 12 is a plan view of the state of FIG.

13 is a plan view of the state of FIG.

[Description of Reference Signs] 1 ... Liquid crystal display device, 2, 3, 30, 40 ... Translucent panel, 4 ... Liquid crystal layer, 5 ... Transparent electrode, 6 ... Light non-transmissive portion, 7 ...
Pixel aperture, 8, 9, 31, 32, 41, 42 ... Glass substrate, 10, 33, 43, 44 ... Recess, 11, 34 ... Plano-convex lens, 45 ... Bi-convex lens.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Atsunori Matsuda 3-5-11 Doshumachi, Chuo-ku, Osaka-shi, Osaka Prefecture Nippon Sheet Glass Co., Ltd. (72) Inventor Kenichi 3 Dosho-machi, Chuo-ku, Osaka-shi, Osaka Chome 5-11 Nippon Sheet Glass Co., Ltd. (72) Inventor Kenji Morio 3-5-11 Doshumachi, Chuo-ku, Osaka City, Osaka Prefecture (chome) Nippon Sheet Glass Co., Ltd. (72) Takashi Kishimoto, Dou-cho, Osaka City, Osaka Prefecture 3-5-11, Machi Within Nippon Sheet Glass Co., Ltd.

Claims (8)

[Claims] 1. A liquid crystal display device comprising a liquid crystal layer provided between a pair of translucent panels, wherein the translucent panel on the side on which the irradiation light is incident is made of two glass plates. A plurality of concave portions are regularly formed on a bonding surface of one glass substrate of the two glass substrates with the other glass substrate, and the high refractive index material is formed in the concave portions. It is filled with a plano-convex lens, and further 2
One of the glass substrates on which the plano-convex lens is formed has a refractive index of n ₁ , the high-refractive-index material serving as the plano-convex lens has a refractive index of n ₂ , and the other glass substrate has a refractive index of n ₃ . When the radius of curvature of the concave portion filled with the refractive index material is r and the thickness of the glass substrate on the liquid crystal layer side of the two glass substrates is t, these satisfy the following relational expression (1a). Characteristic liquid crystal display device. 0.6 / t ≦ (1 / r) (n ₂ −n ₁ ) / n ₃ <1 / t ... (1a) 2. The liquid crystal display device according to claim 1, wherein the recesses filled with the high refractive index material are densely arranged, and when the longest distance between the centers of adjacent recesses is p, 2. A liquid crystal display device characterized by satisfying the relational expression (2a). 1/8 ≦ p (1 / r) (n ₂ −n ₁ ) ≦ 1 / 1.8 ... (2a) 3. The liquid crystal display device according to claim 1, wherein the following relational expression (3a) is satisfied. ^{r- (r 2 -p 2/4} ) 1/2 ≦ 60μm ············· (3a) 4. The liquid crystal display device according to claim 1, wherein the following relational expression (4) is satisfied. ^{r- (r 2 -p 2/4} ) 1/2 ≦ 0.45p ············ (4a) 5. A liquid crystal display device comprising a liquid crystal layer provided between a pair of translucent panels, wherein the translucent panel on the side on which the irradiation light is incident is made of two glass plates. These two glass substrates are formed by joining substrates, and concave portions corresponding to each other are regularly formed on the joining surfaces, and these concave portions are filled with a high refractive index material to form a biconvex lens. the refractive index of the glass substrate n1, the refractive index of the high refractive index material comprising a biconvex lens n2, one of the radii of curvature of the concave portion formed on a glass substrate r ₁ of the two glass substrates, the two When the radius of curvature of the concave portion formed on the other glass substrate of the two glass substrates is r ₂ and the thickness of the glass substrate on the liquid crystal layer side of the two glass substrates is t, these are expressed by the following relational expressions. Liquid crystal table characterized by satisfying (1b) Apparatus. 0.6 / t ≦ (1 / r ₁ + 1 / r ₂ ) (n ₂ −n ₁ ) / n ₁ <1 / t ·· (1b) 6. The liquid crystal display device according to claim 5, wherein the recesses filled with the high-refractive-index material are densely arranged, and the maximum distance between the centers of adjacent recesses is p: 2. A liquid crystal display device satisfying the relational expression (2b). 1/8 ≦ p (1 / r ₁ + 1 / r ₂ ) (n ₂ −n ₁ ) ≦ 1 / 1.8 ... (2b) 7. The liquid crystal display device according to claim 5 or 6, wherein the following relational expression (3b) is satisfied. ^{_{r 1 - (r 1 2 -p}} 2/4) 1/2 ≦ 60μm and ^{_{r 2 - (r 2 2 -p}} 2/4) 1/2 ≦ 60μm ············ ( 3b) 8. The liquid crystal display device according to claim 5 or 6, wherein the following relational expression (4b) is satisfied. ^{_{r 1 - (r 1 2 -p}} 2/4) 1/2 ≦ 0.45p and ^{_{r 2 - (r 2 2 -p}} 2/4) 1/2 ≦ 0.45p ········· .. (4b)