JPH07253574A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To realize means for improving the brightness of a liquid crystal screen with good productivity at a low cost by installing a microlens array between a light source for illumination and a liquid crystal layer and focusing the illumination light to the light transparent regions of the liquid crystal layer. CONSTITUTION:The microlens array 160 is produced by transferring the shape of a prototype for microlens array transfer to transparent plastics, glass, etc. The respective microlenses are so formed as to act as convex lenses. The incident light from a back light etc., on the liquid crystal layer 100 is, therefore, converged for each of respective pixels and the greater part thereof transmits the effective regions 190 of the liquid crystal layer 100. Consequently, the brightness of the liquid crystal screen is improved. The light from angle of a wider range is converged by the microlenses as compared with the case the microlens array 160 is not used. The converted light transmits the liquid crystal screen and is then diverged at wider angles. The visual field angle is thus improved.

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 which is a flat display used for display of information processing terminal equipment such as a computer or display for television.

[0002]

2. Description of the Related Art In recent years, conventional CRTs (Cathode-
As a display that replaces the Ray Tube display, a lightweight, flat-type liquid crystal display has been put into practical use and widely used. One weakness of liquid crystal displays is that the screen is dark compared to CRT displays. By the way, in the pixel of the liquid crystal display, there is a region where the electronic circuit for display control is formed,
This area does not transmit light. As a method of improving the brightness of the screen of a liquid crystal display, it has been proposed to collect light from a backlight or the like in a light transmitting area of each pixel so that light does not reach an opaque area. ing. If such a method can be used, the brightness of the liquid crystal screen can be greatly improved. However, it has not been put into practical use because there is no effective means for focusing the light for each pixel of the liquid crystal display.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to develop a technique for producing a microlens array by a shape transfer technique using transparent plastic, glass, etc., and for each pixel of a liquid crystal display by this microlens array. An object of the present invention is to provide a practical means for improving the brightness of a liquid crystal screen in a liquid crystal display device by making it possible to focus the illumination light.

[0004]

A liquid crystal display according to the present invention.
The spray device includes a liquid crystal layer and a pair of transparent members sandwiching the liquid crystal layer.
Including a bright substrate as a component, composed of multiple pixels,
The liquid crystal layer is illuminated with light from a light source, and liquid crystal is irradiated from the side of transmitted light.
A liquid crystal display device for viewing a crystal screen, the light source
Between the liquid crystal layer and the liquid crystal layer by the shape processing by ion processing.
Microlens array produced by transferring the prototype formed by
Is installed and one microlens or multiple microlenses are installed.
A microlens group of lenses corresponds to each of the pixels
It is characterized by being installed like. here,
The one microlens corresponding to each of the pixels or
Is the shape and size of the lens action area of the minute lens group.
So that it approximately matches the shape and size of the pixel
It is preferably made. Or micro lens
・ The array acts as a lens smaller than the size of the pixel
It consists of a micro lens with a region.
Position on the micro lens array (X, Y) coordinates
The position of the adjacent microlenses is represented by (X₁, Y₁),
(X₂, Y₂), Then X₁≠ X₂, Or Y₁≠
Y₂, Or (X ₁, Y₁) ≠ (X₂, Y₂)connection of
So that the microlens is
It may be arranged in a leh.

[0005]

The operation of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is a schematic cross-sectional view of a liquid crystal display device according to the present invention. 100 is a liquid crystal layer, 110 is a region where light is blocked due to a liquid crystal control circuit, and 120 is 1
A pair of transparent electrodes, 130 and 140 are a pair of transparent substrates, 15
0 is incident light, 155 is outgoing light, 160 is a minute lens array, 170 is one minute lens on the minute lens array 160, and 180 is a range of one pixel. Light blocking area 1
A region 190 between 10 is an effective region of a pixel through which light is transmitted. The microlens array 160 is according to the present invention, and is produced by transferring the shape of the microlens array array master to transparent plastic, glass, or the like.

FIGS. 2A and 2B are typical examples of the microlens array 160, which are a plan view and a sectional view thereof. FIG. 2 (a) is for a monochrome display, and FIG. 2 (b) is for a color display. In FIG. 2A, 180 indicates the spread of one pixel, and 170 indicates one microlens. In this case, one pixel corresponds to one pixel. Figure 2
In (b), 180 indicates the spread of one pixel, and 1
Reference numerals 80B, 180R, and 180G indicate the spread of pixels for each primary color, and 170B, 170R, and 170G indicate one microlens. In this case, one microlens corresponds to one primary color pixel, and one pixel 180
Corresponds to a lens group consisting of a plurality of minute lenses.

As shown in FIG. 1, each minute lens is manufactured so as to act as a convex lens. For this reason,
Light that enters the liquid crystal layer from a backlight or the like is focused on each pixel and most of the light passes through the effective region 190 of the liquid crystal layer. As a result, the brightness of the liquid crystal screen is improved. In addition, compared with the case where no microlens array is used, the microlenses focus light from a wider range of angles and diverge at a wider angle after passing through the liquid crystal screen. Is also effective in improving.

[0008]

【Example】

(Embodiment 1) First, a method for producing a microlens / array transfer master for transferring to transparent plastic or glass will be described. A process for producing a microlens / array transfer prototype is shown in FIGS. 3 (a) to 3 (d). Fig. 3 (a)
In the above, 300 is a substrate having a flat surface, and a quartz glass substrate is used in this embodiment. A metal plate or a ceramic plate can be used as the substrate 300. Board 300
The resist 310 is applied to the resist 310, and the resist 310 has a dimension w
A square or rectangular pattern 320 of × h is formed. A square pattern is used because it can be easily formed, and each pattern may be a circle. This process is L
It is carried out by using a well-known technique such as photolithography and electron beam lithography in SI manufacturing. In the manufacturing process below, the case where the pattern 320 is a square will be described. Next, a liquid containing HF as a main component or C
The substrate 300 is etched by using a gas containing F4 as a main component to form a hole having a depth d in the substrate 300 in the pattern 320 portion. Then, the resist 310 is removed. The state is shown in FIG. 3 (b). 330 is a hole formed in the surface of the substrate 300. Next, the surface of the substrate 300 is removed by using ion processing for removing the material by ion irradiation. Here, in this embodiment, an RF sputtering apparatus is used as the ion processing apparatus and Ar ions are used as the ions. As the ion processing of the substrate 300 progresses, a spherical surface is formed in the portion of the hole 330. This is shown in FIG. 3 (c). Here, when the radius of curvature of the formed spherical surface is R, the initial radius of curvature is R ₀ , and the amount of ion processing is t, the relationship of R = R ₀ + k · t (1) is established. Here, k is a constant determined by the substance, and in quartz glass, k = 7. If the substrate 300 was chemically etched or plus etching, the etching of the substrate 300 proceeds substantially isotropic, R ₀
The relation of = d almost holds. From the equation (1), the curvature R can be controlled by the processing amount t. The holes formed by etching do not have to be spherical, and even if they are not spherical, they become spherical during ion irradiation. FIG. 3 (d) is FIG. 3 (c).
The state of the substrate 300 further ion-processed from the state is shown. In FIG. 3 (d), the spherical surfaces formed from the holes collide with each other, and the regions forming the minute lenses are all spherical surfaces. A quartz glass substrate as shown in FIG. 3 (c) or (d) is used as a prototype for microlens array transfer. Here, as the pattern 320,
When a rectangular or elongated pattern is formed, a shape is formed on the quartz glass substrate such that the end in the longitudinal direction of the pattern is spherical and the other part is cylindrical.

The technique of transferring the shape from the prototype produced by the above method to plastic or the like is a well-known technique, which is carried out, for example, in the production of music records, the production of magneto-optical discs and the like. Therefore, the description of the step of manufacturing the microlens array from plastic or glass from the microlens array transfer master by the transfer technique is omitted. The following examples are intended for a 10-inch type liquid crystal display device. In Examples 2 to 6, the transparent substrates 130 and 140 are glass substrates having a refractive index of 1.5 and a thickness of 0.7 mm, and are manufactured by a transfer technique. The microlens array has a thickness of 0.5 mm and its material has a refractive index of 1.
The case of allyl diglycol polycarbonate of No. 5 will be described.

(Embodiment 2) A case where a 10-inch monochrome liquid crystal display is targeted will be described. First,
A prototype is prepared by the method shown in Example 1. 640 pixels on the surface of the quartz glass substrate at positions corresponding to each pixel at intervals corresponding to a pixel pitch of 300 μm × 330 μm
Form holes of 400 or more. About this hole, the opening (w × h) is about 50 μm × 50 μm, and the depth (d) is about 7
0 μm. Next, Ar gas pressure; 1 Pa, power;
This quartz glass is ion-processed at 800 W by an RF sputtering device. As a result, each hole formed on the quartz glass surface in the ion processing time of about 28 hours becomes a spherical surface having a radius of curvature of about 0.4 mm. As a result, a quartz glass substrate as shown in FIG. 3 (d) is obtained and used as a prototype.

Next, the shape of this prototype is transferred to allyldiglycol polycarbonate to prepare a microlens array in which one surface is flat and microlenses are formed on the other surface. The microlens array is assembled so that the pixels and the microlenses are in one-to-one correspondence, and a liquid crystal display device having a structure as shown in FIG. 1 is manufactured. The micro lens is
It acts as a convex lens with a focal length of about 1.2 mm. This focal length is approximately equal to the sum of the thickness of the transparent substrate and the microlens array. In addition, it is manufactured so that the shape and size of the lens action area of one microlens substantially coincide with the pixel. Therefore, the irradiation light can be efficiently focused on the effective area of each pixel, and the liquid crystal display according to the present invention can reduce the brightness of the liquid crystal screen as compared with the conventional liquid crystal display that does not use such a minute lens. Can be greatly improved.

(Embodiment 3) A case where a 10-inch color liquid crystal display is targeted will be described. The number of pixels of this display is 640 × 400, and the number of pixels is 30
0 μm × 330 μm, and the pixel region for one primary color is 100 μm × 330 μm. First, a prototype is produced by the method shown in Example 1. The opening (w × h) is about 3 μm × 23 for one pixel on the surface of the quartz glass substrate.
Pitch groove 0μm, depth (d) about 3μm; 100μ
3 pixels are arranged by m, and the pixel pitch is set by grouping these 3 grooves;
Number of pixels at intervals corresponding to 300 μm × 330 μm; 64
Form 0 × 400 or more. Next, Ar gas pressure; 1P
a, power: 800 W, this quartz glass is ion-processed by an RF sputtering device. As a result, each groove formed on the quartz glass surface in the ion processing time of about 28 hours has a shape in which a cylindrical surface and a spherical surface having a radius of curvature of about 0.4 mm are combined. This quartz glass substrate is used as a prototype. Next, this prototype is transferred to allyldiglycol polycarbonate to produce a microlens array in which one surface is flat and microlenses are formed on the other surface. Using this microlens array, a liquid crystal display device having a structure as shown in FIG. 1 is manufactured.

The microlenses formed in the microlens array are convex lenses having a combination of a cylindrical lens and a spherical lens, and have a focal length of about 1.2 mm. This focal length is approximately equal to the sum of the thickness of the microlens array and the transparent substrate. Further, it is manufactured so that the shape and size of the lens action area of one microlens are substantially the same as the pixels corresponding to the primary colors. Therefore, the irradiation light can be efficiently focused on the effective area of the area for each primary color in each pixel, and in contrast to the conventional liquid crystal display that does not use such a minute lens, the liquid crystal display according to the present invention is The brightness of the screen can be greatly improved. Here, the microlens array produced in this manner can be applied to the 10-inch monochrome liquid crystal display of Example 2, and substantially the same effect can be obtained.

(Embodiment 4) For the 10-inch type color liquid crystal display of Embodiment 3, a case of using a microlens array consisting of microlenses different in shape from the case of Embodiment 3 will be explained about the fabrication of the prototype. To do.
The other points are the same as those in the third embodiment, and therefore the description thereof will be omitted.
First, a prototype is produced by the method shown in Example 1. On the surface of the quartz glass substrate, an opening (w ×
h) is about 3 μm × 3 μm, and the depth (d) is about 3 μm in pitch; 100 μm × 110 μm is formed in 3 × 3, and this 3 × 3 hole is set as one set, and the set of holes is the pixel pitch; Three
Number of pixels at intervals corresponding to 00 μm × 330 μm; 640
× 400 or more is formed. Next, Ar gas pressure; 1 Pa,
This quartz glass is ion-processed by a RF sputtering device with a power of 800 W. As a result, each hole formed on the quartz glass surface in the ion processing time of about 28 hours becomes a spherical surface having a radius of curvature of about 0.4 mm. This quartz glass substrate is used as a prototype. Here, the microlens array manufactured in this manner can be applied to the 10-inch monochrome liquid crystal display of Example 2, and substantially the same effect can be obtained. In the case of the microlens arrays of Examples 2 to 4, the shape and size of the lens action area of the microlens (Example 2) or the microlens group (Examples 3 to 4) corresponding to each pixel is the same as that of each pixel. It closely matches the shape and size.

(Embodiment 5) A prototype of a 10-inch color liquid crystal display of Embodiment 3 in which a microlens array consisting of microlenses having different shapes from those of Embodiments 3 and 4 is used. Will be described. The other points are the same as those in the third embodiment, and therefore the description thereof will be omitted. First, a prototype is produced by the method shown in Example 1. Formed on the surface of the quartz glass substrate are grooves of width (w): about 3 μm, length (h): 132 mm or more, depth (d): about 3 μm, pitch: 100 μm or more, 640 or more pixels in the X direction. To do. Next, Ar gas pressure; 1 Pa, power; 8
This quartz glass is ion-processed with an RF sputtering device at 00W. As a result, each groove formed on the quartz glass surface in the ion processing time of about 28 hours becomes a cylindrical surface having a radius of curvature of about 0.4 mm. This quartz glass substrate is used as a prototype. Here, a micro lens
The array can be applied to the 10-inch monochrome liquid crystal display of the second embodiment, and the same effect as that of the second embodiment can be obtained.

(Embodiment 6) A method for arranging a microlens / microlens on a 10-inch type color liquid crystal display is described below. An example different from the cases of 2 to 5 will be described. First, a prototype is produced by the method shown in Example 1. A hole having an opening (w × h) of about 1 μm × 1 μm and a depth (d) of about 0.4 μm is formed on the surface of the quartz glass substrate. The arrangement of the holes on the surface of the quartz glass substrate at this time is shown in FIG. As shown in FIG. 4, the coordinates of the hole are represented by (X, Y). The distance between the holes is 33.3 μm in the X direction and 66 μm in the Y direction. However, in reality, the distance between the holes in the X direction is (33.3 μm, 33.3 μm
m, 33.4 μm). If one row of holes in the X direction is set as a set and the X coordinate of a set of holes is used as a reference, the X coordinate of the set of holes immediately above is +6.6.
Each hole is formed at such a position that it is translated by 6 μm in the direction, and the X coordinate of the set of holes immediately below is translated by −6.66 μm in the direction. The area in which this hole is formed is approximately 196 mm × 136 mm. Next, Ar gas pressure;
This quartz glass is ion-processed by an RF sputtering device at 1 Pa and power of 800 W. As a result, each hole formed on the quartz glass surface in the ion processing time of about 28 hours becomes a spherical surface having a radius of curvature of about 0.4 mm. This quartz glass substrate is used as a prototype. Next, an allyldiglycol polycarbonate is transferred to the shape of this prototype to produce a microlens array. Using the microlens array thus produced, a liquid crystal display device having the structure shown in FIG. 1 is assembled.

Each microlens of the microlens array acts as a convex lens with a focal length of about 1.2 mm. In the case of this embodiment, most of the illumination light cannot pass through the effective area of each pixel. However, the small lenses around the light opaque area of the liquid crystal guide the light to the light permeable area,
The brightness of the liquid crystal screen can be increased by 10% or more as compared with the conventional case. Moreover, in the microlens array, since the positions of the microlenses are slightly displaced, it is not necessary to strictly align the microlens array with each liquid crystal pixel. That is, regarding the area for each primary color of each pixel, the number and positional relationship of the minute lenses corresponding to a certain area are almost the same from the viewpoint of light utilization efficiency. In the case of this embodiment, the lens action area of each microlens is set smaller than each pixel.

In this embodiment, the microlenses are slightly displaced in the X direction, but the microlenses may be displaced only in the Y direction or in both the X and Y directions.
It is also possible to prepare a prototype for array transfer. Similar effects can be obtained in those cases as well. Further, although the color liquid crystal display is shown as a target, it is obvious that the microlens array of this embodiment can be applied to a monochrome liquid crystal display.

(Embodiment 7) In Embodiments 2 to 6, the transparent substrate and the microlens array are manufactured separately. Example 7 describes a case where a minute lens array is formed on the transparent substrate itself. If the transparent substrate is made of plastic, the microlens array can be formed on the transparent substrate itself. For that purpose, in the production of the microlens arrays shown in Examples 2 to 6, a plastic suitable for the transparent substrate should be selected and the plastic should have a thickness suitable for the transparent substrate. The plastic substrate with the minute lens array thus produced is used as a substrate on the illumination light source side among the transparent substrates for sandwiching the liquid crystal layer. The other details are the same as those in the other embodiments, and therefore will be omitted. When the transfer master is made of metal, it can be transferred to glass. In the case of one transfer method, the metal mold is heated and the glass plate is pressed there. Even in this case, the lens array can be formed on the transparent substrate itself.

In the above embodiments of the present invention, the 10-inch type liquid crystal display is shown. In addition, the case where the focal length is 1.2 mm and three types of shapes are produced for the minute lens is shown. However, by first selecting the depth of the holes and grooves to be formed in the quartz glass substrate, the shape and arrangement of the holes and grooves, and the ion processing conditions, a microlens having a different size, shape, focal length, etc. from the example was constructed. Microlens arrays can be produced. Therefore, the present invention can be applied to liquid crystal displays other than the liquid crystal screens and pixels shown in the embodiments. The case where the focal length of the microlens is made to approximately match the sum of the thickness of the microlens array and the thickness of the transparent substrate was shown, but by controlling the radius of curvature of the concave surface formed on the quartz glass substrate by the ion processing time, Microlenses with focal lengths other than 1.2 mm can be made. Depending on the configuration of the liquid crystal display, it may be better to set the focal position of the microlens before and after the liquid crystal layer, and such a case can also be dealt with by the present invention.

Further, although the ion processing is performed by the RF sputtering apparatus, any apparatus may be used as long as the ions are incident on the surface to be processed substantially perpendicularly. A quartz glass substrate is used as a substrate for forming a microlens / array transfer prototype by ion processing, but glass substrates other than quartz glass, metal substrates such as aluminum, iron, and copper, ceramic substrates such as alumina and zirconia, etc. Since the concave spherical surface shape can be manufactured by the same method, the above substrate can be used as a prototype manufacturing substrate. Further, although the microlens / array is made of allyldiglycol polycarbonate, various plastics have been commercialized for optical parts, and plastics other than allyldiglycol polycarbonate can be used for microlens / array. It is also possible to transfer the glass by injection molding or pressing. In the embodiment of the present invention, the microlens array is superposed on the transparent substrate, but the microlens array, the polarizing plate and the transparent substrate may be arranged in this order.

[0022]

As described above, according to the present invention, in the liquid crystal display device, the minute lens array is installed between the light source for illumination and the liquid crystal layer, and the illumination light is focused on the light transmitting region of the liquid crystal layer. Therefore, the brightness of the liquid crystal screen can be significantly improved, and since the microlens array is produced by a transfer method from a prototype, a means for improving the brightness of the liquid crystal screen is provided. It can be realized with high productivity and at low cost.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a liquid crystal display device according to the present invention.

2A and 2B are a plan view and a cross-sectional view of a typical example of a microlens array.

[FIG. 3] Manufacturing process of a master for microlens array transfer.

FIG. 4 is an arrangement of holes on a quartz glass substrate in Example 6.

[Explanation of symbols]

 100 ... Liquid crystal layer 110 ... Light blocking region 120 ... Transparent electrodes 130, 140 ... Transparent substrate 150 ... Incident light 155 ... Emission light 160 ... Microlens array 170 ...・ Microlens 180 ・ ・ ・ 1 pixel range 300 ・ ・ ・ Substrate 310 ・ ・ ・ Photoresist 320 ・ ・ ・ Pattern

Claims (3)

[Claims] 1. A liquid crystal layer and a pair of transparent substrates sandwiching the liquid crystal layer are included as constituent parts and are composed of a plurality of pixels. The liquid crystal layer is illuminated with light from a light source, and a liquid crystal screen is displayed from the side of transmitted light. In a liquid crystal display device to be viewed, a microlens array made by transferring a prototype formed by ion processing is installed between the light source and the liquid crystal layer, and one microlens or a plurality of microlenses is provided. A liquid crystal display device, wherein a microlens group including microlenses is installed so as to correspond to each of the pixels. 2. The liquid crystal display device according to claim 1, wherein the microlens array has a shape and size of a lens action area of the one microlens or the microlens group corresponding to each of the pixels. A liquid crystal display device, characterized in that the liquid crystal display device is manufactured so as to substantially match the shape and size of the pixel. 3. The liquid crystal display device according to claim 1,
And the microlens array is smaller than the size of the pixel.
Consists of a micro lens with a small lens working area
The position of this microlens on the microlens array
Position is represented by (X, Y) coordinates, and the position of the adjacent micro lens is
(X₁, Y₁), (X₂, Y₂), Then X₁≠
X₂, Or Y₁≠ Y₂, Or (X₁, Y₁) ≠
(X₂, Y ₂) The microlens so that the relationship
Are arranged in the microlens array
Liquid crystal display device.