JPH1184403A - Liquid crystal display device and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a device which enables bright color display and is relatively simple in production stages by providing the device with a first liquid crystal cell having a liquid crystal layer added with black a dyestuff and a second liquid crystal cell injected with the liquid crystals added with the dyestuffs of different colors in plural blocks so as not to be mingled between these blocks. SOLUTION: The liquid crystal display device is constituted by forming the guest-host type liquid crystal cells to a two-layered structure. The first layer is a black and white display cell 1 and the second layer is a color display cell 2. The liquid crystals added with the black dyestuffs are injected into the black and white display cell 1. The liquid crystal layer of the color display cell 2 has the plural blocks partitioned by barriers 3 at a pixel unit. The liquid crystals added with the dyestuff are injected into the respective blocks. The one cell 1 of two layers of the cells is capable of making black and white display and the other cell 2 makes color display. If the respective layers are independently subjected to driving control, the white display, the color display, the black display and the medium contrast display are made possible by the combination of the display states of the respective layers.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a liquid crystal display device and a liquid crystal display device, and more particularly to a liquid crystal display device suitable for guest-host mode color display and a method of manufacturing the same.

[0002]

2. Description of the Related Art A color display system of a liquid crystal display device uses a color filter system comprising a combination of a color filter and a liquid crystal cell for controlling light transmission on / off, a three-layer type guest-host mode, or birefringence. STN mode and the like.

[0003]

A color display system using a color filter is convenient in that almost all types of liquid crystal cells can be used. However, a color filter is expensive, and light emitted by the color filter is difficult. Since light transmitted through the cell is reduced due to the loss, it is difficult to obtain a bright white display, which is not a desirable method for a reflection type liquid crystal display device or the like.

On the other hand, in a three-layer type guest host mode color display system, a manufacturing process for obtaining a cell having a three-layer structure is complicated. Further, in order to reduce the optical path difference of transmitted light, it is desirable that the glass substrate between the layers has a small thickness, but the thinner the thickness is, the more difficult the manufacturing process of the liquid crystal cell is and the lower the pressure resistance is. is there. There is also a problem that it is difficult to obtain a clear color display (color purity is low).

Further, the birefringence mode color display system has disadvantages such as low color purity, narrow viewing angle, and poor brightness due to the use of a polarizing plate.

SUMMARY OF THE INVENTION An object of the present invention is to provide a liquid crystal display device capable of performing bright color display and having a relatively simple manufacturing process, and a method of manufacturing the same.

[0007]

In a liquid crystal display device according to one aspect of the present invention, a first liquid crystal cell and a second liquid crystal cell are arranged so as to overlap with each other. The first liquid crystal cell has a liquid crystal layer to which a black dye is added. The second liquid crystal cell has a plurality of sections separated from each other, and a liquid crystal in which a dye of a different color is added to the plurality of sections is injected so as not to mix between the sections.

Further, a liquid crystal display device according to another aspect of the present invention has first and second liquid crystal cells arranged so as to overlap with each other, and each liquid crystal cell has a plurality of partitions separated from each other. Then, liquid crystals in which dyes of different colors are added to the plurality of sections are injected so as not to mix with each other. The sections of the first and second liquid crystal cells are arranged so as to oppose each other in the light transmission direction, and the dyes of the opposing sections of the first and second liquid crystal cells have a complementary color relationship with each other.

A method of manufacturing a liquid crystal display according to another aspect of the present invention includes the following steps. A plurality of first and second empty cells are formed by stacking a plurality of substrates on which a plurality of pixel electrodes are formed. A liquid crystal to which a black dye is added is injected into the first empty cell. A plurality of sections separated from each other corresponding to the pixel electrodes are formed in the second empty cell. Liquid crystals to which different color dyes are added are injected into the plurality of sections of the second empty cell so as not to mix with each other.

A method for manufacturing a liquid crystal display according to another aspect of the present invention includes the following steps. A plurality of first and second empty cells are formed by superposing a plurality of substrates on which a plurality of pixel electrodes are formed. In each of the first and second empty cells, a plurality of sections separated from each other are formed corresponding to the pixel electrodes.
At this time, the first and second liquid crystal cells are formed so that the sections thereof are opposed to each other in the light transmission direction. Liquid crystals to which dyes of different colors are added are injected into a plurality of sections of the first and second empty cells so as not to mix with each other. Liquid crystals to which dyes of different colors which have a complementary color relationship with the dye of the first liquid crystal cell are injected into the plurality of sections of the second empty cell.

[0011]

The cell of one of the two layers can display black and white, and the cell of the other layer can be displayed in color. If the driving of each layer is controlled independently, the white state can be obtained by combining the display state of each layer. Display, color display, black display and half-tone display are also possible.

[0012] Alternatively, of the two-layer cells, one layer cell is displayed in three primary colors and the other layer cell is displayed in a complementary color relationship with the one cell, and each layer is driven independently. If controlled, white display, color display, black display, and half-tone display can be performed depending on the combination of the display states of the respective layers.

[0013]

FIG. 1 is a partially enlarged sectional view of a color liquid crystal display device according to a first embodiment of the present invention. The liquid crystal display device has a guest-host type liquid crystal cell having a two-layer structure. The first layer is a monochrome display cell 1, and the second layer is a color display cell 2. The black-and-white display cell 1 is filled with a liquid crystal to which a black dye is added. The liquid crystal layer of the color display cell 2 has a plurality of sections separated by partitions 3 in pixel units. Liquid crystal to which a dye is added is injected into each section.

Hereinafter, the structure and display operation will be described in more detail. The first guest-host type liquid crystal cell 1 includes:
A light reflecting plate 11 is provided on the surface of an insulating substrate 10 such as a glass plate.
Is formed thereon, and a transparent pixel electrode 12 of ITO or the like is formed thereon, and an alignment film 13a is further applied thereon, and an alignment process is performed as necessary. Opposing insulating substrate 1
Reference numeral 4 denotes a transparent glass plate, on which a transparent common electrode 15 is formed on its lower surface, and an alignment film 13b is further formed thereon, and an alignment process is performed as necessary.

A liquid crystal layer 16 is disposed with a gap control material (not shown) dispersed between the substrates 10 and 14. The liquid crystal layer is a guest-host liquid crystal made of a liquid crystal to which a black dye is added. A drive voltage can be applied between the common electrode 15 and the pixel electrode 12. LCD is ON
The pixels 17 and 18 in the state (light transmission state) display white.
The pixel 19 in which the liquid crystal is in the OFF state (light opaque state) displays black. The area without the pixel electrode 12 is in the OFF state.

On the other hand, the second guest-host type liquid crystal cell 2
Is placed on the upper surface of the upper substrate 14 of the first cell 1
A transparent pixel electrode 20 of O or the like is formed, and an alignment film 21 is further applied thereon, and an alignment process is performed as necessary. The opposing insulating substrate 22 is a transparent glass plate,
A transparent common electrode 23 is formed on the lower surface, and an alignment film 24 is further formed thereon, and an alignment process is performed as needed. The pixels of the first cell 1 and the pixels of the second cell 2 are positioned so as to face each other.

Further, the second guest-host type liquid crystal cell 2
Are partitioned from each other by partition walls 3 made of a polymer to form a plurality of pixel sections. Liquid crystals to which a dye is added are injected into each section. The partition walls 3 prevent the liquid crystals from being mixed between the sections. The pixel region 25 is filled with a liquid crystal to which a green dye is added. Liquid crystal to which a blue dye is added is injected into the pixel region 26.
The pixel region 27 is filled with liquid crystal to which a red dye is added.

The pixel area 17 of the first cell 1 is ON and in a white display state, and the pixel area 25 of the second cell 2 above it is ON.
In the state of the non-coloring mode, the display surface 30 becomes white. When the pixel region 18 of the first cell 1 is in the white display state when ON and the pixel region 26 of the second cell 2 above it is in the OFF state in the coloring mode, the display surface 40 turns blue. First
When the pixel region 19 of the cell 1 is OFF and the pixel region 19 is in the black display state, the reflected light does not transmit. Therefore, even in the coloring mode in which the pixel region 27 of the second cell 2 above is OFF, the display surface 50 The display becomes black.

The relationship between the display state of the pixel and the display color will be described in more detail with reference to FIG. As shown in FIG. 2A, when all three pixels of the first cell 1 are turned off and all the R, G, and B pixels of the second cell are turned off, a black display is obtained as a whole. .

As shown in FIG. 2B, all three pixels of the first cell 1 are turned off, and R, G,
If all the pixels of B are turned on, (A)
Black, that is, gray display, which is slightly lighter than the black of the above.

As shown in FIG. 2C, the R pixel of the second cell 2 is turned off (colored), the pixel of the first cell 1 below it is turned on (light transmission), and the other pixels are turned on. O for all pixels
In the FF state, a red display is obtained as a whole.

As shown in FIG. 2D, the R pixel of the second cell 2 is turned off, the pixel of the first cell 1 thereunder is turned on, and all the other pixels are turned on. As a display, a red display brighter than the red of (C) is obtained as a whole. However, the color purity is slightly reduced. The driving modes (C) and (D) are the same for the other G pixels (green) and B pixels (blue).

As shown in FIG. 2E, all three pixels of the first cell 1 are turned on, and R, G, B of the second cell are turned on.
If all the pixels are turned on, white display can be obtained as a whole.

It will be apparent to those skilled in the art that the first and second layers may be interchanged. First to display black and white
The layer is not limited to the guest-host type, and for example, a polymer dispersion type (PDLC) liquid crystal display device utilizing confusion may be used.

[0025]

Next, a method of manufacturing the liquid crystal display of FIG. 1 will be described with reference to FIG. A two-layer empty cell as shown in FIG. 3A is created, and a solvent 4 containing a polymerization initiator and a monomer is injected between the substrates of the second cell 2. The steps of forming an electrode, an alignment film or a TFT element (not shown) on each substrate, and the step of spraying a gap control agent (not shown) can be performed by a conventional technique, and thus description thereof is omitted. I do.

Further, as shown in FIG. 3B, the cell obtained in the step of FIG. 3A is overlaid with a photomask 5 and exposed to ultraviolet light. The photomask 5 has a pattern in which only the display portion of the pixel is shielded from light and light passes through the boundary portion between adjacent pixels. Irradiation of the ultraviolet rays polymerizes the monomer at the irradiated portion, thereby forming a polymer partition wall 3. The solvent remains in the region where the ultraviolet light has not been applied, but the remaining solvent is removed by evaporating by heat treatment or the like.

Next, as shown in FIG. 3B, the rooms 25, 26, 2 partitioned by the polymer wall 3 of the second cell 2 are formed.
Liquid crystals to which a desired dye is added are injected into 7, 28.
For example, liquid crystals to which a green pigment is added to the rooms 25 and 28, a blue pigment to the room 26, and a red pigment to the room 27 are individually injected. On the other hand, a liquid crystal 16 to which a black dye is added is injected between the substrates of the first cell 1.

In order to inject three color liquid crystals into each room of the second cell 2 so as not to mix with each other, the pattern of the photomask 5 when forming the polymer wall 3 is devised. For example, a pattern as shown in FIG. 4 is used.

FIG. 4A is a plan view of the pattern of the photomask 5. Reference numeral 51 denotes a portion (ultraviolet transmitting portion) corresponding to the polymer wall 3. FIG. 4B is a plan view of the second cell 2 exposed as described with reference to FIG.
Shown in 52 is a liquid crystal injection port to which a red dye is added,
Reference numeral 53 denotes a liquid crystal injection port to which a green dye is added. Red and green liquid crystals are injected from the respective injection ports. Next, FIG.
As shown in (C) to (E), the injection port 52 of the red liquid crystal is sealed, the cell is cut along the cut line 54, and the remaining liquid crystal to which the blue dye is added is injected from the injection port 55. Finally, if the injection port is completely sealed as shown in FIG.
Liquid crystals of three different colors are injected into individual rooms so that they do not mix with each other. Note that the pattern of the photomask 5 is not limited to that shown in FIG. For example, three colors of liquid crystal may be injected by sequentially injecting liquid crystal and cutting cells from one side.

FIG. 5 is an enlarged partial sectional view of a liquid crystal display device according to a second embodiment of the present invention. The structure different from the embodiment of FIG. 1 is that polymer barrier ribs 8 for partitioning similar pixels are provided in both cells of the first layer and the second layer. Although the exposure step of forming the polymer partition wall can be performed by one exposure, it is advantageous to perform the exposure from both sides to shorten the exposure time. It is obvious that the present embodiment can perform the same operation as the first embodiment.

In this case, the color of each pixel of the second cell 2 and the color of the corresponding pixel of the first cell 7 can be complementary to each other. For example, if the liquid crystal of the pixel portion 25 of the second cell 2 is green, the pixel portion 71 of the first cell 7 that is opposed is magenta, and the liquid crystal of the pixel portion 26 of the second cell 2 is blue. For example, the pixel portion 72 of the opposing first cell 7 is yellow, and if the liquid crystal of the pixel portion 27 of the second cell 2 is red, the opposing pixel portion 73 of the first cell 7 is cyan. .

In the guest-host type phase change mode without hysteresis, halftone display can be easily performed by controlling the applied voltage. The orientation may be vertical or horizontal. In the case of the bistable guest-host type phase change mode with hysteresis, halftone display cannot be performed by a single cell, but some halftone display is possible depending on the area gradation. In the bistable mode, bright display is possible.

In the phase change mode, simple matrix driving is possible. When active matrix driving is performed using a TFT or the like, a scattering mode such as a guest host mode and a polymer dispersion mode can be employed in addition to the two guest host type phase change modes.

In the manufacturing process of the liquid crystal display device of the second embodiment, the first cell forming step is the same as the second cell forming step. Therefore, the process is somewhat more complicated than in the case of the first embodiment.

As a solvent for dissolving the monomer when forming the partition wall in the above embodiment, for example, isopropyl alcohol or the like may be used, but other solvents may be used. The partition may be formed by another method.

Contrast performance is obtained by adding a chiral agent to the liquid crystal to be injected and changing the direction of alignment treatment applied to the alignment film between the electrodes in the layer to give an appropriate twist to the liquid crystal molecular state in the layer. Is advantageous. For example, a twist angle from about 90 degrees to about 390 degrees can be considered. In the case of a bistable guest-host type phase change mode using hysteresis, the twist may be further increased. Further, in the above embodiments, the reflection plate is formed in the cell, but may be arranged outside the substrate of the cell. Further, on a substrate on which a reflector is formed, a conductive reflector may be used as a pixel electrode instead of the transparent electrode.

The present invention is not limited to the embodiments described above, and it will be apparent to those skilled in the art that various modifications and improvements can be made based on the disclosure of the embodiments.

[0038]

As described above, it is possible to obtain a liquid crystal display device capable of performing bright color display and having a relatively simple manufacturing process, and a manufacturing method thereof.
For example, of the two layers of cells, one layer of cells is displayed in black and white, the other layer is displayed in color, and if each layer is independently driven and controlled, a white display, Color display, black display, and halftone display are also possible.

Alternatively, of the two-layer cells, one layer cell is displayed in color, and the other layer cell is displayed in a color complementary to the cell in one layer, and each layer is independently driven and controlled. For example, white display, color display, black display, and intermediate gradation display can be performed depending on the combination of the display state of each layer.

[Brief description of the drawings]

FIG. 1 is a partially enlarged cross-sectional view of a liquid crystal display according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram illustrating a principle of a color display operation of the liquid crystal display device according to the first embodiment.

FIG. 3 shows a manufacturing process of the liquid crystal display device according to the first embodiment.

FIG. 4 shows a step of injecting liquid crystals of three colors.

FIG. 5 is a partially enlarged cross-sectional view of a liquid crystal display according to a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 1st cell 2 2nd cell 3 Partition wall 4 Monomer solvent 5 Photomask 10 Insulating substrate 11 Reflector 12 Pixel electrode 13a, 13b Alignment film 14 Insulating substrate 15 Common electrode

Claims (14)

[Claims] 1. A first liquid crystal cell having a liquid crystal layer to which a black dye is added, and a plurality of sections arranged so as to overlap with the first liquid crystal cell and separated from each other. A liquid crystal display device comprising: a second liquid crystal cell into which liquid crystals to which dyes of different colors are added are injected so as not to mix between the sections. 2. A first liquid crystal cell having a plurality of sections separated from each other, wherein a liquid crystal in which a dye of a different color is added to the plurality of sections is injected so as not to be mixed between the sections. A second liquid crystal cell having a plurality of sections which are arranged so as to overlap with the first liquid crystal cell and are separated from each other, and in which a liquid crystal in which a dye of a different color is added is injected into the plurality of sections so as not to mix between the sections; Wherein the first and second liquid crystal cell sections are disposed so as to face each other in the light transmission direction, and the opposing dyes of the first and second liquid crystal cell sections have complementary colors to each other. The liquid crystal display device that is involved. 3. The liquid crystal display device according to claim 1, further comprising a partition partitioning said plurality of partitions. 4. The liquid crystal display device according to claim 3, wherein the material of the partition includes a polymer. 5. The liquid crystal display device according to claim 1, wherein the pigments of different colors are any of a combination of blue, red and green, or a combination of cyan, magenta and yellow. 6. The liquid crystal display device according to claim 1, wherein said first and second liquid crystal cells are guest-host type phase change liquid crystal cells. 7. The liquid crystal display device according to claim 1, wherein said first and second liquid crystal cells are bistable guest-host type phase change liquid crystal cells utilizing hysteresis. 8. The liquid crystal display device according to claim 6, wherein the sections of the first and second liquid crystal cells have electrode means capable of applying or not applying a voltage independently of each other. 9. A step of forming a first and a second two-layer empty cell by stacking a plurality of substrates on which a plurality of pixel electrodes are formed, and a step of applying a liquid crystal obtained by adding a black dye to the first empty cell. Injecting; forming, in the second empty cell, a plurality of sections that are separated from each other corresponding to the pixel electrodes; and applying a dye of a different color to the plurality of sections of the second empty cell. Injecting the added liquid crystal so as not to mix with each other. 10. A step of forming a first and a second two-layer empty cell by stacking a plurality of substrates on which a plurality of pixel electrodes are formed; and forming the first empty cell in correspondence with the pixel electrode. Forming a plurality of sections separated from each other; and forming a plurality of sections separated from each other corresponding to the pixel electrodes in the second empty cell, wherein the first and second sections are formed.
Forming the partitions so that the partitions of the liquid crystal cell are arranged to face each other in the light transmission direction; and mixing the liquid crystals obtained by adding the dyes of different colors to the plurality of partitions of the first empty cell. A step of injecting so that no liquid crystal is added to the plurality of sections of the second empty cell, and a liquid crystal in which a dye of a different color having a complementary color relationship with a dye of the section of the first liquid crystal cell is added to each other. A method of manufacturing a liquid crystal display device, comprising: 11. The method for manufacturing a liquid crystal display device according to claim 9, wherein the step of forming the plurality of sections includes the step of forming a partition partitioning each section by a photolithography process. 12. The method according to claim 11, wherein the material of the partition includes a polymer. 13. The method for manufacturing a liquid crystal display device according to claim 9, wherein the dyes of different colors are any of a combination of blue, red and green, or a combination of cyan, magenta and yellow. 14. The liquid crystal display according to claim 9, wherein the liquid crystal is injected into the first and second empty cells to form a bistable guest-host type phase change liquid crystal cell utilizing two layers of hysteresis. Device manufacturing method.