JPH03288801A - Optical element, its production, and display element using the same - Google Patents

Abstract

PURPOSE:To obtain an optical element increasing the aperture rate of picture elements and consisting of the array of fine optical elements constituting a bright screen by forming a low melting point (MP) glass layer on a transparent glass substrate with a high MP and executing the hot press molding of the whole layers by plural press molding metal molds coated with a chemically stabilized thin film. CONSTITUTION:The plane press molding metal mold, the high MP transparent glass substrate 3 on which the MP glass layer 4 is formed and the press molding metal mold forming concave microlens shapes on its surface are successively set up from the uppermost layer and the hot press molding of these layers is executed in a molding machine held at atmosphere in which nitrogen gas is allowed to flow in the rate of 20 liters/min. When the layers are gradually cooled down to 300 deg.C together with the cooling of the press molding metals after the press molding, the fine optical element forming the glass layer 4 and a convex lens array 7 on the substrate 3 is obtained. The radius of curvature of the array 7 is determined so that light is focused on the position of a transparent electrode 9 constituting a picture element. Since light on an aperture part or light in the vicinity of the aperture part are concentrated into the aperture part of each picture element, the aperture rate of the picture element is practically increased and a display having a bright screen and high picture quality can be obtained.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention is applicable to liquid crystal displays, plasma displays,
The present invention relates to an optical element comprising an array of microscopic optical elements used in a display element such as an electroluminescent display, a method for manufacturing the same, and a display element using the same.

Conventional technology In recent years, CRT (CATHOD RAY TUBE)
Various thin display elements have been proposed as an alternative to cathode ray tubes (e.g., cathode ray tubes).As a thin display element capable of color display with a large display capacity, an active matrix type display element in which a thin film transistor (TPT) is formed in each pixel has been proposed. Liquid crystal displays are attracting particular attention.

In such a display element, light from a light source is transmitted through the aperture of each pixel, so the light transmittance depends on the aperture ratio of the pixel. In a liquid crystal display with positive phase accuracy, when very small pixels are formed at high density, there is a limit to reducing the size of TPT, and the TPT that occupies a pixel
The area of will be relatively large. In other words, the aperture through which light passes becomes smaller (decreased aperture ratio),
The amount of transmitted light decreases. Due to the decrease in the amount of transmitted light, the screen becomes dark and the display image quality deteriorates.

As a method to solve this problem, a method has been considered in which the light that was previously absorbed by the wiring and the light shielding body that are essential to the TPT type formation is effectively utilized by condensing it into the aperture of the pixel using a lens. For example, Japanese Patent Application Laid-Open No. 165624/1983 describes that spherical microlenses are formed by subjecting the glass substrate itself to conventional mechanical processing. Furthermore, Japanese Patent Laid-Open No. 1-189685 describes that microlenses are formed on an optically polished glass substrate by press-molding a thermally deformable resin.

Problems to be Solved by the Invention However, in the case of JP-A-60-165624,
For example, a 3-inch ultra-high-density liquid crystal display requires approximately 1 million microlenses, and it is difficult to process such a large number of microlenses, approximately 1 million microlenses. It is extremely difficult and nearly impossible to mass-produce such microlenses. On the other hand, in the case of JP-A-1-189685, the material of the microlens portion is a resin which is an organic compound. -Resins, which are organic compounds for boat fishing, have a coefficient of thermal expansion nearly an order of magnitude higher than glass substrates, and are more susceptible to expansion and contraction due to temperature changes. Therefore, when using a microlens formed on a glass substrate for a long period of time, the precise position between the pixel and the microlens may shift, the radius of curvature of the lens may change, or the microlens may peel off from the glass substrate. happens.

The present invention solves the above-mentioned problems, and is an optical element comprising an array of microscopic optical elements without fear of thermal deformation or peeling, used in display elements such as liquid crystal displays and electroluminescent displays with bright screens, and a method for manufacturing the same. The present invention also aims to provide a display element using the same.

Means for Solving the Problems In order to achieve the above object, the present invention uses a press molding die in which a low melting point glass layer is formed on a high melting point transparent glass substrate and is coated with a chemically stable thin film. An optical element is manufactured by forming an array of desired microscopic optical elements made of low melting point glass on a high melting point transparent glass substrate by hot press bottom shaping, and then each pixel in a display element holding a display material is manufactured. Correspondingly, the optical element obtained by the above manufacturing method is arranged.

Operation According to the above-described configuration, the present invention condenses light at and near the aperture onto the aperture of each pixel by a micro optical element array made of low-melting glass formed on a transparent glass substrate. Therefore, the aperture ratio of the pixels is substantially increased, making it possible to provide a bright screen and a display with high display image quality. In addition, by hot forming with a press molding die processed into the shape of the desired micro optical element array,
High-precision micro optical element arrays and display elements can be manufactured with extremely high mass productivity.

EXAMPLES Hereinafter, examples of the present invention will be described with reference to FIGS. 1 to 4.

Example 1゜As shown in Fig. 1, 50 +++ m of cemented carbide (WC-57iC-8Co) was used as the base material l of the press molding die.
It was cut into a flat plate of x 40 g x 10++ nn square, and was lapped and polished using ultrafine diamond powder to give a mirror surface with a surface roughness (RMS) of about 3 nm. The base material 1 has a mirror surface, and the radius of curvature is 40011.
Approximately 800,000 concave microlens shapes were formed in a lattice pattern with a pitch of 40 μm using an indentation device using highly accurate numerical control of a hemispherical diamond indenter. On top of this, platinum-iridium-osmium alloy (Pt-1r-
A thin film 2 of Os) was coated to prepare a mold for press molding.

In Figure 2, 3 is a high melting point transparent glass substrate with a polished surface (#7059.40 x 30 m manufactured by Corning).
X1.1), and 4 is a low melting point glass layer. Silica (S10□) 30% by weight, barium oxide (B
ad) Sputtering a barium borosilicate glass target consisting of 50% by weight, 15% by weight of boric acid (BzOi), and the balance being trace components to form a low melting point glass layer 4 with a thickness of 10 μm on a high melting point transparent glass substrate 3. Coated. 5 is a base material of a flat press molding die, and 6 is a thin film of platinum-iridium-osmium alloy on the base material 5, which was produced in the same manner as the press molding die described above.

As shown in FIG. 2, from above, a flat press mold, a high melting point transparent glass substrate 3 formed with a low melting point glass layer 4,
A press molding die with a concave microlens mold was set in this order, and hot press molding was carried out in a molding machine maintained in an atmosphere in which nitrogen gas was flowing at 20 liters per minute. Press molding conditions are mold temperature 560°C, press pressure 30kg.
/cd, press time was 2 minutes. After press molding, the micro optical element is slowly cooled together with the press mold to 300'C to form a low melting point glass layer 4 and a convex lens array 7 on a transparent glass substrate 3 as shown in FIG. I got it.

As shown in FIG. 4, a thin film transistor (TPT) 8 made of amorphous silicon and a transparent electrode 9 made of ITO constituting a pixel are formed on the opposite surface of a transparent glass substrate 3 on which a convex lens array 7 of a micro optical element is formed. Then, a polarizing plate 10 was attached to the surface facing the convex lens array 7. A transparent common electrode 12 made of TTO is provided on one entire surface of a flat transparent glass substrate ti, and a color filter 13 is provided on the common electrode 12 at a position corresponding to the transparent electrode 9 constituting the pixel. A polarizing plate 14 was attached to the surface. The transparent glass substrates 3 and 11 having such a structure were fixed with an adhesive (not shown), and a liquid crystal material 15 was injected into the gap therebetween. In such a display element, incident light 1
6 are incident in parallel, if the voltage applied between the common electrode 12 and the transparent electrode 9 constituting the pixel is on, the polarized wave passes through the liquid crystal material 15 without changing, and the applied When the applied voltage is off, the plane of polarization of light passing through the liquid crystal material 15 is rotated by 90 degrees and cannot pass through the liquid crystal material 15.

The radius of curvature of the convex lens array 7 is determined so as to focus at the position of the transparent electrode 9 constituting the pixel, and the incident light 16 that has passed through the convex lens array 7 is directed to the transparent electrode 9 which is the aperture.
The light is focused on the common electrode 2 and the transparent glass substrate 11.
Transparent. As is clear from FIG. 4, when the incident light 16 is incident in parallel, almost all of the light is transmitted through the transparent electrode 9 constituting the pixel, which is the aperture, without being blocked by the thin film transistor 8, and is displayed. Contributed effectively. Therefore, the aperture ratio of the pixels is substantially increased, making it possible to create a display with a bright screen and high display image quality.

Example 2゜Austenitic steel JS as base material 1 of press molding die
tJs3]6) 50ao x 40mm x 10m
It was cut into n-square plates, lapped and polished using ultrafine diamond powder to give a mirror surface with a surface roughness (RMS) of about 3 ns+. As shown in Fig. 1, about 80 concave microlens shapes are injected into the mirror-surfaced base material 1 in a lattice pattern at a pitch of 40 μm using a highly precisely numerically controlled indentation device using a hemispherical diamond indenter with a radius of curvature of 400 μm. There were 10,000 forms of power. On top of this, a thin film 2 of rhodium-gold-tungsten alloy (Rh-Au-W) was applied by sputtering.
was coated to make a press molding mold.

In Figure 2, 3 is a transparent glass substrate with a polished surface (
4 is a low melting point glass layer, 8 weight percent zirconia (ZrOz), 30 weight percent lanthanum oxide (1,az Oa), boric acid (BzC)+). A lanthanum glass containing 42% by weight, 10% by weight of calcium oxide (Cab), and the balance being trace components was used. A slurry liquid of ultrafine particles of lanthanum-based glass was uniformly applied to the entire surface of the transparent glass substrate 3 to a thickness of about 20 μm using a blade coater.

After drying this, it is placed at the bottom of a pit in an 800°C electric furnace in the air.
A low melting point glass layer 4 was coated on a transparent glass substrate 3. 5 is a base material of a flat press mold, and 6 is a rhodium-gold-tungsten alloy (Rh-
Au-W) thin film, and was produced in the same manner as the press molding die described above.

As shown in Fig. 2, from above, the base material of a flat press mold, a transparent glass substrate 3 formed with a low melting point glass layer 4, and a press mold formed with a concave microlens mold are shown. lol
The bottom of the press was hot pressed in a molding machine maintained in an atmosphere containing 2.0 liters of nitrogen gas for 7 minutes and 1 liter of hydrogen gas for 7 minutes. The press molding conditions were a mold temperature of 680''C, a press pressure of 10 kg/cd, and a press time of 2 minutes.

After press molding, it was slowly cooled to 400'C together with the press mold to obtain an optical element in which a convex lens array 7 was formed on a transparent glass substrate 3 as shown in FIG.

As shown in FIG. 4, 'FrIWIj!' made of amorphous silicon is placed on the opposite side of the transparent glass substrate 3 on which the convex lens array 7 of the micro optical element is formed. Transistor (TPT
) 8 and a transparent electrode 9 made of ITO constituting a pixel, and a polarizing plate 1 is placed on the convex surface and -7 side.
I pasted 0. A common electrode 12 made of ITO is provided on one entire surface of a flat transparent glass substrate 11, a color filter 13 is provided on the common electrode 12 at a position corresponding to the transparent electrode 9 constituting the pixel, and a color filter 13 is provided on the other surface of the common electrode 12. A polarizing plate 14 was attached. Transparent glass substrates 3 and 1 having such a structure
1 was fixed with an adhesive (not shown), and a liquid crystal material 15 was injected and filled into the gap. In such a display element, when the incident light 16 is incident in parallel and the voltage applied between the common electrode 12 and the transparent electrode 9 constituting the pixel is on, the light passing through the liquid crystal material 15 is polarized. The wavefront passes through unchanged, and when the applied voltage is off, the plane of polarization of the light passing through the liquid crystal material 15 is rotated by 90 degrees and cannot pass through the liquid crystal material 15.

The radius of curvature of the convex lens array 7 is determined so as to focus at the position of the transparent electrode 9 constituting the pixel, and the incident light 16 that has passed through the convex lens array 7 is directed to the transparent electrode 9 which is the aperture.
The light is focused on the common electrode 12 and the transparent glass substrate 11.
Transparent. As is clear from FIG. 4, when the incident light 16 is incident in parallel, almost all of the light is transmitted through the transparent electrode 9 constituting the pixel, which is the aperture, without being blocked by the thin film transistor 8, and is displayed. Contributed effectively. Therefore, in effect, the aperture ratio of the pixel was increased (thus, a bright screen and a display with high display image quality could be obtained).

Example 3 Cerment (T i
c-10Mo-9N i) 50+s x 40m
It was cut into a flat plate of x 10wm square, and was then ramped and polished using ultrafine diamond powder to give a mirror surface with a surface roughness (RMS) of about 2nm. As shown in Fig. 1, about 80 concave microlens shapes are injected into the mirror-surfaced base material 1 in a lattice pattern at a pitch of 40 μm using a highly precisely numerically controlled indentation device using a hemispherical diamond indenter with a radius of curvature of 400 μm. There were 10,000 forms of power. On top of this, platinum-tantalum-rhenium alloy (P t -Ta
-Re) was coated with a thin film 2 to prepare a press molding mold.

The thin film coated on the press-molding die is preferably made of noble metals such as tungsten, tantalum, rhenium, and hafnira, which do not react or fuse with low-melting glass, or alloys thereof.

The atmosphere in which the low melting point glass and these thin films do not react or fuse together is an inert gas such as nitrogen, argon, helium, etc., and these inert gases contain hydrogen, carbon oxide, carbon oxide such as carbon dioxide, Hydrocarbons such as methane, ethane, ethylene, and toluene, halogenated hydrocarbons such as trichloroethylene and trichlorotrifluoroethane, alcohols such as ethylene glycol and glycerin, and fluorocarbons such as F-113 and F-11 are appropriately mixed. It is desirable that the atmosphere be a non-oxidizing atmosphere.

These atmospheres or press molding conditions (temperature, time, and pressure) are appropriately selected depending on conditions such as the low melting point glass composition, the thin film composition coated on the press molding die, or the optical shape of the micro optical element array.

In Figure 2, 3 is a transparent glass substrate with a polished surface (
Alkali-free glass, Asahi Glass AN, 40×30oo×1
．． 1m), 4 is a low melting point glass layer, and silica (
SiO2) 52% by weight, potassium oxide (K2O
) 6% by weight, lead oxide (Pb(1) 35% by weight, sodium oxide (Na2(1) 5% by weight, the balance being trace components. S i (OCH, ) n , P b (Oi C=
H? ) A uniform G shape was applied over the entire surface of the transparent glass substrate 3 to a thickness of about 5 μm using a sol-gel method using a metal alkoxide such as 2. After drying this, the transparent glass substrate 3 was coated with a low melting point glass layer 4 by being bottomed in an electric furnace at 750° C. in the air. 5 is a base material of a flat press molding die, and 6 is a platinum-cuntal-rhenium alloy (
It was a pt-Ta-Re)l film, and was produced in the same manner as the press molding die described above.

As shown in Fig. 2, from above, the base material of the flat press mold, the transparent glass substrate 3 formed with the low melting point glass layer 4, and the press mold formed with the concave microlens mold are arranged in this order. The material was then hot press-molded in a molding machine maintained in an atmosphere containing a mixture of 20 liters/min of helium gas and 2 liters/min of carbon dioxide gas. Press molding conditions are mold temperature 520"C, press pressure 20kg/c11T
, the press time was 1 minute. After press molding, the convex lens array 7 is formed on the transparent glass substrate 3 by slowly cooling it to 350° C. together with the press molding die, as shown in FIG.
We have obtained an optical element with an impressive shape.

As shown in Figure 4, micro optical element array 〇 convex lens array 7
A thin film transistor (TPT) 8 made of amorphous silicon and a transparent electrode 9 made of TTO constituting a pixel are formed on the opposite side of the transparent glass substrate 3, and a polarizing plate 10 is formed on the side facing the convex lens array 7. I pasted it. ITO is applied to one entire surface of the flat transparent glass substrate 11.
A color filter 13 is provided at a position corresponding to the transparent electrode 9 constituting the pixel.
A polarizing plate 14 was attached to the other surface.

The transparent glass substrates 3 and 11 having such a structure were fixed with an adhesive (not shown), and a liquid crystal material 15 was injected into the gap therebetween. In such a display element, when the incident light I6 is incident in parallel, if the voltage applied across the common electrode 12 and the transparent electrode 9 constituting the pixel is on, the light passing through the liquid crystal material 15 is The plane of polarization passes through unchanged,
When the applied voltage is off, the plane of polarization of light passing through the liquid crystal material 15 is rotated by 90 degrees and cannot pass through the liquid crystal material 15.

The radius of curvature of the convex lens array 7 is determined so as to focus at the position of the transparent electrode 9 constituting the pixel, and the incident light 16 that has passed through the convex lens array 7 is directed to the transparent electrode 9 which is the aperture.
The light is then focused on the common electrode 12, the transparent glass substrate Fi,
Transmit ll. As is clear from Fig. 4, the incident light 1
When the light beams 6 were incident in parallel, almost all of the light was not blocked by the thin film transistor 8 and was transmitted through the transparent electrode 9 constituting the pixel, which is the aperture, contributing effectively to the display. Therefore, the aperture ratio of the pixels is substantially increased, making it possible to create a display with a bright screen and high display image quality.

For comparison, a display element having a structure similar to the conventional one as shown in FIG. 5 was fabricated.

In FIG. 5, the convex lens array 7 is made of resin material, and other than that, the structure is the same as in FIG. 4. When incident light 16 enters a display element having such a configuration in parallel, the radius of curvature of the lens changes due to temperature changes, and the lens focuses at a position shifted from the pixel, and in extreme cases, As shown by the dotted line, light reached the non-aperture and did not contribute to the display. Further, after using it for about one month, the convex lens array 7 made of a resin material peeled off from the transparent glass substrate 3.

In addition, in the optical element of the present invention, its manufacturing method, and display element using the same, press molding conditions (temperature, time, pressure, and atmosphere), low melting point glass material and its manufacturing method, press bottom shape and molded matrix The material and the composition of the thin film covering it, the shape of the micro optical element array and its manufacturing method, the display principle of the display element, the element configuration, etc. are not limited to the present example.

Effects of the Invention As is clear from the above examples, the optical element of the present invention, the method for manufacturing the same, and the display element using the same can be realized by a micro optical element array made of low melting glass formed on a transparent glass substrate. The aperture and light near the aperture are focused on the aperture of each pixel. Therefore, the aperture ratio of the pixel is substantially increased, and a bright screen and display with high display quality can be obtained. In addition, such display elements are resistant to thermal deformation and peeling from the substrate, and are made into highly accurate micro-optical elements by being hot-formed in a press-molding die processed into the desired shape of the micro-optical element array. Optical elements and display elements consisting of arrays can be manufactured with extremely high mass productivity.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a press molding die in an embodiment of the present invention, FIG. 2 is a sectional view showing a state of press molding of a micro optical element array, and FIG. 3 is a sectional view showing a micro optical element array. FIG. 4 is a sectional view showing a display element array, and FIG. 5 is a sectional view showing the configuration of a comparative example display element using a conventional micro optical element array. ■・・・・・Base material for press molding mold, 2・・・・−
・Thin film, 3...High melting point transparent glass substrate, 4-
.--Low melting point glass layer, 5.--.Base material for press mold, 6-..thin film, 7.--Convex lens (micro optical element) array 8. ... Thin film transistor, 9...Transparent electrode, 10...Polarizing plate, 11...-Transparent glass substrate, 12...
Common electrode, 13...Color filter, 14.
...Polarizing plate, 15...Liquid crystal material, 16.
...Incoming light.

Claims (5)

[Claims] (1) An optical element in which a low melting point glass layer and micro optical elements formed in an array of low melting point glass are provided on a high melting point transparent glass substrate. (2) A method for producing an optical element, in which a high melting point transparent glass substrate with a low melting point glass layer formed on its surface is hot press-molded using a press molding die processed into the shape of a desired microscopic optical element array. (3) The method for manufacturing an optical element according to claim (2), wherein the press molding die is coated with a chemically stable thin film. (4) The method for manufacturing an optical element according to claim (3), wherein the thin film is made of a noble metal, tungsten, tantalum, rhenium, or hafnium, or an alloy thereof. (5) In a display element comprising at least a display material constituting a pixel and a high melting point transparent glass substrate holding the display material, a low melting point glass layer and a low melting point glass layer on the high melting point transparent glass substrate and corresponding to each pixel are provided. A display element using an optical element formed by forming a micro optical element array made of low melting point glass.