JPH05134266A - Display element and its formation - Google Patents

Abstract

PURPOSE:To easily form the high-brightness display element having the high efficiency of utilizing light by using a liquid crystal layer and a high-polymer layer as plural thin layers varying in refractive index. CONSTITUTION:A high-polymer material layer 103 and the liquid crystal layer 104 are laminated between transparent conductive films 101 and 102. The high- polymer material layer 103 consists of a photo- or thermosetting type high- polymer material having the refractive index n3. The liquid crystal layer 104 consists of a twisted nematic liquid crystal which can be varied in refractive index from n1 to n2 (n1>n2>n3). A voltage is impressed between the transparent conductive films 101 and 102 by a power source 105, by which the refractive index of the liquid crystal layer 104 is made into n1 to reflect the light mainly consisting of, for example, red and to allow the transmission of the light exclusive of this light. The refractive index of the liquid crystal layer 104 is made into n2 when the voltage is not impressed between the transparent conductive films 101 and 102. The reflectivity of the light in the wavelength band of red is then drastically decreased and the greater part of the light is transmitted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device and a method for forming the same.

[0002]

2. Description of the Related Art FIG. 6 is a schematic view showing a conventional transmissive display device. In this transmissive display device, the backlight 40
The structure in which the white light is supplied by 2 and the polarizing plate 403 is arranged on both sides of the TN type or STN type liquid crystal 401 is used as an optical shutter, and the emitted white light is colored by the color filter 4.
It is colored by 04 and a display operation is performed.

FIG. 7 is a schematic view showing a conventional reflective display device. In this reflective display device, TN type or ST
The structure in which the polarizing plates 503 are arranged on both sides of the N-type liquid crystal 501 is used as an optical shutter, and the white light emitted is colored by the color filter 504, which is similar to the transmissive display device shown in FIG. A reflective plate 502 is provided instead of the backlight, and a display operation is performed using only the reflected light.

FIG. 8 is a schematic view showing a conventional reflective color display device using a polymer dispersed liquid crystal. In this reflective color display device, a dye 603 is further added to a polymer dispersion type liquid crystal which is a mixture of a liquid crystal 601 which is a dispersoid and a polymer 602 which is a dispersion medium, and a color film 604 is formed behind the dye 603, for example, in a mosaic shape. The reflector 605 is disposed behind the color film 604.

In this reflection type color display device, in the scattering mode (state in which no voltage is applied) shown in FIG. 8A, light scattered by the difference in refractive index between the liquid crystal 601 and the polymer 602 is polymer 602. Since it is absorbed by the dye 603 contained in the liquid crystal or in the liquid crystal 601, a black color is displayed,
Further, the transmission mode shown in FIG. 8B (state in which voltage is applied)
In, the color of the rear color film 604 is developed.

However, in the transmissive display device shown in FIG. 6, since the backlight 402 has a large volume and the power consumption of this portion is large, it is difficult to make it thin and portable.

Further, in the reflection type display device shown in FIG.
Since only the reflected light is used, the amount of light is small, so it is necessary to greatly increase the light use efficiency of the optical shutter as compared with the case of a transmissive display device. However, the TN type or STN type liquid crystal 5
01 is simply used, the essential polarizing plate 5
Due to the presence of No. 03, the utilization efficiency of reflected light is reduced to at least less than half, and it is difficult to achieve high brightness.

Further, in the reflection type color display device using the polymer dispersed liquid crystal shown in FIG. 8, the light is absorbed by the dye 603 even in the transmission mode, so that the brightness is lowered.

Therefore, the inventors of the present invention have solved the above problems, made it easier to make the device thinner and lighter, and made it easier to achieve high brightness. He devised a Japanese patent application No. 2-306265).

FIG. 9 is a schematic view showing a display element described in Japanese Patent Application No. 2-306265. In this display element, a transparent film 702 having a refractive index n3 is arranged on a conductive film 701, and the refractive index n1 to n2 on the film 702 is changed by an electric field.
A transparent film 703 that is variable up to (n1 <n2 <n3), for example, a liquid crystal (including polymer ferroelectric liquid crystal) or a ferroelectric substance is arranged, and a refractive index n3 is provided on the transparent film 703 that has a variable refractive index.
Transparent film 704 is disposed, and a transparent conductive film 705 is disposed on the transparent film 704.

In this display element, as shown in FIG. 9 (a), the refractive index of the transparent film 703 whose refractive index is variable and n1 is variable by the voltage applied between the conductive film 701 and the transparent conductive film 705. Then, the refractive index as a whole is n3 / n1 / n3
And the well-known principle of interference filters (for example, optical thin film (edited by Shiro Fujiwara, Kyoritsu Shuppan, 19
1986)), light in a specific wavelength band is reflected, and other light is transmitted. Further, as shown in FIG. 9B, when the refractive index of the transparent film 703 having a variable refractive index is changed by the voltage applied between the conductive film 701 and the transparent conductive film 705 to be n2, the multilayer film The refractive index difference between the films 702 to 704 is variable and the transparent film 703 has a refractive index n.
Since it is smaller than in the case of 1, the reflectance of light in a specific wavelength band is significantly lowered, and most of the light is transmitted.

Therefore, by using this display element, it is possible to configure a device that can control reflection and transmission of light in a specific wavelength band and always transmit light in other wavelength bands.

[0013]

[Problems to be Solved by the Invention] However, Japanese Patent Application No. 2-3
In the display device described in No. 06265, in order to improve the light utilization efficiency and realize a display capable of bright display without a backlight, a thin layer having a different refractive index is used.
It is necessary to repeatedly stack the layers at a fine interval of μm or less, and for this purpose, a plurality of films made of different materials must be deposited many times, which complicates the manufacturing process.

The present invention has been made in order to solve the above-mentioned problems, and is a high-brightness color display which does not require a backlight and is easy to be made light and thin, and which does not require a polarizing plate and has high light utilization efficiency. Display element, which can create a device
An object of the present invention is to provide a method for forming a display element, which can easily form a high-brightness display element with high light utilization efficiency.

[0015]

In order to achieve this object, according to the present invention, a plurality of thin layers having different refractive indexes are laminated, and the refractive index of one or more thin films among the thin layers is changed by an electric field. In the variable display element, a liquid crystal layer and a polymer material layer are used as the plurality of thin layers having different refractive indexes.

Further, in a display element in which a plurality of thin layers having different refractive indexes are laminated, and the refractive index of one or a plurality of thin films among the thin layers is changed by an electric field, a liquid crystal is used as the plurality of thin layers having different refractive indexes. And a polymer material are used, and the ratio of the liquid crystal to the polymer material is different.

Further, in a display element in which a plurality of thin layers having different refractive indexes are laminated, and the refractive index of one or more thin films among the thin layers is changed by an electric field, a liquid crystal is used as the plurality of thin layers having different refractive indexes. And a polymer material are used, and the sizes of the liquid crystal regions in the polymer material are made different.

Further, a polymer material made of a photo- or thermosetting polymer material is mixed with liquid crystal, and a plurality of laser beams are irradiated to the mixture of the polymer material and the liquid crystal, whereby an interference pattern of the laser beam is obtained. A thin layer having a different refractive index is formed by the light intensity layer.

[0019]

In this display device and the method for forming the same, it is possible to extremely easily repeatedly stack thin layers having different refractive indexes at fine intervals.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on the embodiments shown in the drawings.

(Display Element 1) FIG. 1 is a schematic view showing a display element according to the present invention. In this display element, a light or thermosetting polymer material (for example, thermosetting polymer material: epoxy resin (e.g., thermosetting polymer material) having a refractive index n3 is formed between two transparent conductive films 101 and 102 made of, for example, an ITO film having a film thickness of 500 Å. n3 = 1.3), or a photocurable polymer material:
A polymer material layer 103 made of light track LA0208 (n3 = 1.5)) and a twisted nematic liquid crystal whose refractive index is variable from n1 to n2 (n1>n2> n3) by an electric field (for example, E-7: manufactured by Merck). n1 = 1.7
5 and n2 = 1.52). Further, 105 is a power supply for changing the refractive index of the liquid crystal layer 104.

In this display element, as shown in FIG. 1A, by applying a voltage between the transparent conductive film 101 and the transparent conductive film 102, the refractive index of the liquid crystal layer 104 becomes n.
If it is 1, the refractive index as a whole is n3 / n1 / n3 ...
It is equivalent to a multilayer structure of n3 / n1 / n3 (n1 = 1.75, n3 = 1.5), and is a well-known principle of interference filters (for example, optical thin film (edited by Shiro Fujiwara, Kyoritsu Shuppan, 1
986)), for example, the polymer material layer 10
3. If the thickness of the liquid crystal layer 104 is 1000 Å, light having a wavelength of 6500 Å mainly in red is reflected and other light is transmitted. Further, as shown in FIG. 1B, by applying no voltage between the transparent conductive film 101 and the transparent conductive film 102, the refractive index of the liquid crystal layer 104 becomes n.
2, the refractive index is n3 / n2 / n3 ... n3 / n2
/ N3 (n2 = 1.52, n3 = 1.5) has a multilayer structure, and the difference in refractive index between the polymer material layer 103 and the liquid crystal layer 104 is small. Therefore, the reflectance of light in the red wavelength band around the wavelength 6500Å is significantly reduced, and most of the light is transmitted. In this display element, the polymer material layer 10
3. When 20 or more liquid crystal layers 104 are repeatedly formed, by applying a voltage, the polymer material layer 103,
When the refractive index difference of the liquid crystal layer 104 is increased, 90% or more of red light can be reflected. When the difference in refractive index between the polymer material layer 103 and the liquid crystal layer 104 is small,
The reflection of red light is 10% or less. Therefore, a display element capable of controlling reflection and transmission of light in a specific wavelength band can be formed in this embodiment, and by this display element, lightness and thinness without using a backlight, easy portability, and no need for a polarizing plate A high-brightness color display device with high light utilization efficiency can be manufactured.

Although the case of n1> n3 is shown here as an example, it is obvious that the same display operation can be performed even when the material of n3> n1 is used.

Even when n1>n3> n2, if the value of n3 is sufficiently close to the value of n1 or n2,
Obviously, the same display operation is possible.

Further, the polymer material layer 103 and the liquid crystal layer 10
Although the film thicknesses of No. 4 are 1000 l, respectively, the invention is not limited to this, and the wavelength of reflected light can be changed by changing the film thickness.

(Display Element 2) FIG. 2 is a schematic view showing another display element according to the present invention. In this display element, light or thermosetting polymer material 203 (for example, thermosetting polymer material: epoxy resin) having a refractive index n3 is formed between two transparent conductive films 201 and 202 made of, for example, an ITO film having a film thickness of 500Å. (N3 = 1.3), or a photocurable polymer material: light rack LA0208 (n3 = 1.
5)), a small liquid crystal region, for example, a liquid crystal droplet having a diameter of about 500 Å made of twisted nematic liquid crystal (for example, E-7 manufactured by Merck & Co., Inc .: n1 = 1.75, n2 = 1.52) was formed. A multi-layer structure of a small droplet layer 205 and a large droplet layer 207 in which large liquid crystal droplets having a diameter of, for example, about 1000 Å are formed is formed. When the size of the liquid crystal droplets is different, the content ratio of the liquid crystal in the polymer material 203 is different, and therefore the refractive indices of the small droplet layer 205 and the large droplet layer 207 are also different. Therefore, a multi-layer structure having different refractive indexes is formed. When the refractive index of the liquid crystal is changed by the electric field, the large droplet layer 207 contains a large amount of the liquid crystal, and thus the large droplet layer 207 has a large change in the refractive index. On the other hand, since the small droplet layer 205 has a small amount of liquid crystal, the change in the refractive index of the small droplet layer 205 is small. For this reason,
Large droplet layer 207 and small droplet layer 205
The difference in the refractive index between and can be changed by an electric field. For example, the content of the twisted nematic liquid crystal in the large droplet layer 207 is 80%, and the content of the twisted nematic liquid crystal in the small droplet layer 205 is 2%.
When it is 0%, the large droplet layer 20 when an electric field is applied
7 has a refractive index of about 1.7, and the small droplet layer 20
The refractive index of 5 becomes about 1.55, and a difference in refractive index occurs.
Therefore, according to the well-known principle of an interference filter (see, for example, an optical thin film (edited by Shiro Fujiwara, Kyoritsu Shuppan, 1986)), for example, the small droplet layer 205 and the large droplet layer 207 each have a thickness of 1000 Å. Then, the light mainly composed of red light having a wavelength of about 6500Å is reflected and the other light is transmitted. In addition, the transparent conductive film 20
1 and the transparent conductive film 202, when the refractive index of the large droplet layer 207 is n2, the refractive index is n3 / n2 / n3 ... n3 / n2 / n3 (n2 = 1.
52, n3 = 1.5), and the difference in refractive index between the small droplet layer 205 and the large droplet layer 207 becomes small. For this reason, the reflectance of red light near the wavelength of 6500Å is significantly reduced, and most of the light is transmitted. In this display element, when 20 or more small droplet layers 205 and large droplet layers 207 are repeatedly formed, by applying a voltage, the small droplet layers 2 are formed.
05, when the difference in the refractive index of the large droplet layer 207 is increased, 80% or more of red light can be reflected. Further, when there is no difference in the refractive index between the small droplet layer 205 and the large droplet layer 207, the reflection of red light is reduced to 1
It can be 0% or less. Therefore, similarly to the above-described embodiment (display element 1), a display element capable of controlling reflection and transmission of light in a specific wavelength band can be formed in this embodiment, and the display element can be made light and thin without using a backlight, and can be carried. It is possible to produce a high-luminance color display device which is easy to realize, requires no polarizing plate, and has high light utilization efficiency.

(Method 1 for Forming Display Element) FIG. 3 is a schematic view for explaining the method for forming a display element according to the present invention. In the method of forming this display element, first, referring to FIG.
As shown in FIG. 2, for example, a twisted nematic liquid crystal (E-7 manufactured by Merck & Co.) and a light or thermosetting polymer material (for example, ICI Dispense mixture 303 with LUXTRACK LCR 208). Next, as shown in FIG. 3B, the mixture 303 is irradiated with the argon laser light 304 having a wavelength of 488 nm from two directions from the upper and lower sides. At this time, the argon laser beam 304 causes interference and a specific interval d (for example, 2500Å interval).
In this way, an interference pattern 305 in which the intensity of laser light is generated is obtained. The intensity of this light occurs at a minute interval determined by the wavelength of the light and the angle of incidence of the two lights (see, for example, holography (Takashi Ogoshi, edited by the Institute of Electronics and Communication Engineers, 1977)). At this time, if the mixture 303 contains a photo-curable polymer material, as shown in FIG.
The photo-curable polymer material is cured in a region of the interference pattern 305 where the interference light is irradiated and the light intensity is high. Further, the mixture 303 is a thermosetting polymer material (eg, epoxy resin).
, The interference pattern 3 of the mixture 303
Heat is generated in the region where the light intensity of the interference light of 05 is high and the thermosetting polymer material is cured. Therefore, the liquid crystal mainly gathers in the weak light region. As a result, the liquid crystal layer 306 containing only liquid crystal or a large amount of liquid crystal and the polymer material layer 307 containing only a polymer material or containing a large amount of polymer material are separated into fine (for example, 2500Å intervals). A multilayer structure can be produced.

When the light intensity is high and the curing speed of the light or thermosetting polymer material is high, the liquid crystal is deposited as liquid crystal droplets. The size of the liquid crystal droplet is smaller as the curing speed is higher. That is, a small liquid crystal droplet with a diameter of 100 Å is formed in a region where the light intensity is increased due to light interference (for example, an argon laser beam: a region having an intensity of about 20 mW / cm ² or more at a wavelength of 4880 Å). Become. Further, in a region where the light intensity is weak, liquid crystal droplets having a diameter of about 1000Å or more are formed. At this time, as shown in FIG. 5, a multi-layer structure of a small droplet layer 309 having small liquid crystal droplets formed therein and a large droplet layer 311 having large liquid crystal droplets formed in a region where the curing speed is relatively slow. However, since the small droplet layer 309 and the large droplet layer 311 have different liquid crystal contents, the refractive indices also differ. Therefore, a multilayer structure having different refractive indexes can be formed.

Since the refractive index of the liquid crystal layer 306 or the large droplet layer 311 changes with the application of a voltage, the difference in refractive index between the liquid crystal layer 306 and the polymer material layer 307, the small droplet layer 309, and the large droplet layer 311. By appropriately setting the refractive index difference of, it is possible to manufacture a display element capable of controlling the reflection and transmission of light in a specific wavelength band,
With this display element, a display device can be manufactured in which a polarizing plate is unnecessary and light utilization efficiency is high.

According to this method of forming a display element, regions having different refractive indexes can be repeatedly arranged at fine intervals of about wavelength intervals by a step of only irradiating laser light,
A display element having an extremely high light reflectance can be easily manufactured.

According to this method of forming a display element,
By changing the irradiation directions of the two laser beams, the direction and the interval of the interference pattern can be arbitrarily changed, so that the regions having different refractive indexes can be formed at arbitrary intervals and in any direction. Therefore, it is possible to easily manufacture display elements having reflected light and reflected intensity in various wavelength bands.

In the above embodiments, liquid crystal is used as the material whose refractive index changes, but polymer liquid crystal, ferroelectric liquid crystal, etc. whose refractive index changes with voltage may be used. Further, although an argon laser is used to obtain the interference pattern, any light source having a uniform phase from which interference light can be obtained may be used.

[0033]

As described above, according to the display element of the present invention, it is possible to make the device thin and thin without using a backlight, to easily carry it, to use a polarizing plate and to have a high brightness color with high light utilization efficiency. According to the method for forming a display element of the present invention, it is possible to fabricate a display device, and it is possible to extremely easily repeatedly stack thin layers having different refractive indexes at fine intervals. A bright display element can be easily formed. As described above, the effect of the present invention is remarkable.

[Brief description of drawings]

FIG. 1 is a schematic view showing a display device according to the present invention.

FIG. 2 is a schematic view showing another display element according to the present invention.

FIG. 3 is a schematic diagram for explaining a method of forming a display element according to the present invention.

FIG. 4 is a schematic view showing a display element formed by the method for forming a display element described in FIG.

FIG. 5 is a schematic view showing another display element formed by the method of forming a display element described in FIG.

FIG. 6 is a schematic view showing a conventional transmissive display device.

FIG. 7 is a schematic view showing a conventional reflective display device.

FIG. 8 is a schematic view showing a reflective color display device using a conventional polymer-dispersed liquid crystal.

FIG. 9 is a schematic view showing a display element described in Japanese Patent Application No. 2-306265.

[Explanation of symbols]

 103 ... Polymer Material Layer 104 ... Liquid Crystal Layer 205 ... Small Droplet Layer 207 ... Large Droplet Layer 303 ... Mixture 304 ... Argon Laser Light 305 ... Interference Pattern 306 ... Liquid Crystal Layer 307 ... Polymer Material Layer 309 ... Small Droplet Layer 311 ... Large droplet layer

Claims (4)

[Claims] 1. In a display device in which a plurality of thin layers having different refractive indexes are laminated, and a refractive index of one or more thin films among the thin layers is changed by an electric field, a liquid crystal is provided as the plurality of thin layers having different refractive indexes. A display element comprising a layer and a polymer material layer. 2. In a display device in which a plurality of thin layers having different refractive indexes are laminated, and the refractive index of one or more thin films among the thin layers is changed by an electric field, a liquid crystal is provided as the plurality of thin layers having different refractive indexes. And a polymer material, wherein the liquid crystal and the polymer material are mixed in different ratios. 3. A display device in which a plurality of thin layers having different refractive indexes are laminated, and the refractive index of one or more thin films among the thin layers is changed by an electric field, and a liquid crystal is used as the plurality of thin layers having different refractive indexes. And a polymer material, wherein the size of the liquid crystal region in the polymer material is different. 4. A light or thermosetting polymer material is mixed with a liquid crystal and liquid crystal, and a plurality of laser beams are irradiated to the mixture of the polymer material and the liquid crystal, and the interference pattern of the laser light is obtained. A method of forming a display element, comprising forming a thin layer having a different refractive index by a light intensity layer.