JPH0743477B2 - Color liquid crystal display device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a color liquid crystal display device capable of full-color display, and more particularly to a cell structure.

<Prior Art> Conventionally, various systems have been proposed as a color display device using a liquid crystal. Among them, on the inner surface of the liquid crystal cell,
A color liquid crystal display device in which a color filter layer having a fine pattern of red, green, and blue is formed has a characteristic that full color display is possible with a relatively simple cell structure.
As such a color liquid crystal display system, two systems have been proposed so far.

First, the first method, the gelatin as shown in FIG. 5, a relief pattern consisting of glue or casein, by the technique of photolithography, red, green, the color filter 1 ₁ stained to blue color, 1 _2, 1 ₃ , a twisted nematic liquid crystal and two neutral polarizers 3 ₁ and 3 ₂ are combined. In the figure, 4 ₁ and 4 ₂ are glass substrates, and A ₁ and A ₂ represent the polarization directions of the neutral polarizers 3 ₁ and 3 ₂ . Further, the transparent electrode and the liquid crystal molecular alignment film are omitted.

In this method, the two neutral polarizers 3 ₁ and 3 ₂ are normally set so that the polarization directions are parallel to each other. When the voltage is off, black is displayed, and when the voltage is on, the liquid crystal molecules of the pixel are in the electric field. And the color of the color filter is observed. Red-green,
By appropriately selecting the voltage applied to each of the blue picture elements independently, it is possible to display any color other than black. However, with this method, in the case of monochromatic display of red, green, and blue, only 1/3 of the whole display can be contributed to the display, and only a dark display is obtained. Actually, it is possible to perform bright display with excellent contrast by placing a light source on the back side, but considering the advantages of liquid crystal display such as low power consumption and thinning, it is possible to place a light source on the back side. The restriction that it cannot be used if it is not placed is not very desirable.

Next, as a second method, as shown in FIG. 6, there is a method of combining the neutral polarizer 6 with the color polarizers 5 ₁ , 5 ₂ , 5 _{3 in} which dichroic dyes are aligned in one direction. . (This method is, JP 58-7177, the 58-17420 Patent, it has already been proposed at the same 58-17421 No. or the like.) In addition, in the figure, 8 _1, 8
₂ is a glass substrate, B and C are each an absorption axis direction of the polarization direction and the color polarizer 5 _1, 5 _2, 5 ₃ neutral polarizer 6. Further, the transparent electrode and the liquid crystal molecular alignment film are omitted.

Similar to the first method, this method has two problems that black display cannot be performed in addition to the problem that only 1/3 of the whole can be displayed in the case of monochromatic display of red, green and blue.
When there is no electric field, the polarization direction of linearly polarized light is 5 ₁ , 5
_To match the absorption axis directions of ₂ , 5 ₃ respectively, red,
Observed as green and blue colors. Next, when applying an electric field,
Linearly polarized light is not absorbed by the color polarizer 5 _1, 5 _2, 5 _3, it is observed as a colorless. In this method, since an arbitrary color is displayed in white or colorless, the whole becomes bright, but on the other hand, there is a problem that the display contrast is poor.

In order to solve the above problems, when a single color display is performed by stacking liquid crystal layers using color polarizers in two layers, 2/3 of the picture elements or 3/3 of the picture elements Cell structures that contribute to display have been proposed.

<Problems to be Solved by the Invention> As shown in FIG. 7, the cell structure of the liquid crystal display device of the type in which monochromatic display is performed by 3/3 picture elements has first and second layers stacked in two stages. the liquid crystal layer 9, 10, patterned color polarizer 12i of two layers in the respective complementary colors on the glass substrate 11 and 16 ₂ constituting the liquid crystal layers, 13i and 14i, the 15i for each picture element It is composed of

In order to pattern the color polarizer, it is necessary to selectively dye each color of red, green, blue or cyan, magenta, and yellow by a photo process, so that the process is still complicated. Color liquid crystal displays remain a problem.

The present invention has been made in view of the above points, and an object of the present invention is to provide a color liquid crystal display device which has a bright display and can simplify the manufacturing process of a color polarizer.

<Means for Solving Problems> The present invention provides a stacking relationship that is selectively set to rotate a polarization direction of incident polarized light by 90 ° by applying or not applying a voltage or to transmit the incident polarized light as it is. Forming two color polarizers having different absorption characteristics from each other and the absorption axis directions thereof orthogonal to each other with respect to the arranged first and second liquid crystal layers, in each of the first and second liquid crystal layers, The polarization direction arranged on one side of the first liquid crystal layer is orthogonal or parallel to the absorption axis direction of the color polarizer 1.
In a color liquid crystal display device composed of a sheet of neutral polarizer, the first-layer color polarizer and the second-layer color polarizer that are laminated and formed on the first and second liquid crystal layers have complementary color relationships, Each of the color polarizers of the first layer or the second layer has two colors, and the first and second picture elements of the first liquid crystal layer are different from the first to third picture elements adjacent to each other. The first and second picture elements corresponding to each other in the second liquid crystal layer have different color combinations.
The third picture element of the liquid crystal layer and the first picture element of the second liquid crystal layer have the same color combination, and the first and second picture elements of the first liquid crystal layer and the second picture element of the second liquid crystal layer It is composed of a combination of colors different from the element and the third picture element.

<Embodiment> The embodiment will be described in detail based on the present invention.

FIG. 1 is a sectional view showing a cell structure of an embodiment of the present invention. Polyvinyl alcohol (hereinafter referred to as PV) uniaxially stretched on one glass substrate 11 constituting the first liquid crystal layer 9 of the liquid crystal cell.
A film is attached and dyed in a predetermined pattern with red and green dichroic dyes, and red and green color polarizers
Form 19,20. In this embodiment, two picture elements of which one group is three picture elements are the red color polarizer 19 and the remaining one picture element is the green color polarizer 20.

Further, a uniaxially stretched PVA film is attached onto the first layer color polarizer. In this case, it is necessary to attach the first layer and the second layer so that the stretching directions are orthogonal to each other.
Next, the second layer of PVA film is dyed into a predetermined pattern in the same manner as the first layer by using cyan and magenta dichroic dyes, and 2
The color polarizers 22 and 23 of the layer are formed. However, in this case, the PVA film of the second layer is dyed so that the colors of the color polarizer of the first layer and the color polarizer of the second layer have a complementary color relationship with each other.

Then stain second PVA film pasting predetermined pattern and uniaxially stretching the other on the glass substrate 16 _{and second} liquid crystal layer 10. First, the PVA film of the first layer is dyed in a predetermined pattern using dichroic dyes of green and blue to form green and blue color polarizers 20 and 21. Here, the blue color polarizer 21 is a picture element, and the two picture elements are formed corresponding to the red and green picture elements in the first liquid crystal layer 9. Further, a uniaxially stretched PVA film is attached onto the color polarizer of the first layer. Then, the second layer of PVA film is dyed in a predetermined pattern in the same manner as the first layer using magenta and yellow dichroic dyes to form second layer color polarizers 23 and 24.

After forming a transparent conductive film on each of the color polarizers of the first and second liquid crystal layers by a method such as low temperature sputtering, the transparent electrode is etched into a predetermined pattern and the transparent electrode 25 ₁ ,
25 ₂ , 25 ₃ , 28 ₁ , 28 ₂ , 28 ₃ are formed. Further, after forming the transparent electrodes, the liquid crystal molecular alignment films 27 ₁ and 30 ₁ are formed respectively.
The other substrate facing the color polarizer in the first and second liquid crystal layers 9 and 10 is a transparent electrode 26, 29 on the glass substrate,
Liquid crystal molecular alignment films 27 ₂ and 31 ₂ are formed.

After the above substrates are bonded and sealed, a twisted nematic liquid crystal is injected.

When the glass substrates 11, 16 ₁ and 16 ₂ of the first and second liquid crystal layers are laminated, they are laminated so that their display picture elements are the same, and one is placed outside the laminated liquid crystal layer and on the incident light side. A neutral polarizer 18 is provided. In the figure, D is the polarization direction of the neutral polarizer, E ₁ and E ₂ are the absorption axis directions of the color polarizers of the first and second layers of the first liquid crystal layer 9, and E ₃ and E ₄ are It is the absorption axis direction of the color polarizers of the first and second layers of the second liquid crystal layer 10. The polarization direction of the neutral polarizer 18 is orthogonal or parallel to the absorption axis direction of each color polarizer.

The operating principle of this embodiment will be described below. FIG. 2 shows the case of black display. The linearly polarized light that has passed through the neutral polarizer 18 does not rotate in the polarization direction because the liquid crystal molecules of the first liquid crystal layer 9 are vertically aligned, and the first layer color polarizers 19, 2
At 0 it is colored red and green. Also in the second liquid crystal layer 10, since the liquid crystal molecules are vertically aligned, they are absorbed by the green and blue color polarizers 20 and 21 of the first layer, so that all the picture elements are observed as black.

Next, the case where red is displayed in all picture elements will be described. Regarding the picture elements on the left side of FIG. 3, since the liquid crystal molecules are vertically aligned in the first liquid crystal layer 9, the color polarizer 19 of the first layer is colored red and enters the second liquid crystal layer 10 as it is. Since the liquid crystal molecules are twisted by 90 °, the polarization direction is also twisted by 90 ° and is absorbed by the magenta color polarizer 23 in the second layer, but the red light passes through as it is. Since liquid crystal molecules are vertically aligned in the first liquid crystal layer 9 with respect to the central picture element, the second liquid crystal layer 10 is colored as red by the color polarizer 19 of the first layer.
Then, the liquid crystal molecules are twisted 90 °, and the polarization direction is also twisted 90 ° accordingly. Then, the red light is absorbed by the yellow color polarizer 24 of the second layer, but passes through as it is. With respect to the picture element on the right side, the liquid crystal molecules are twisted by 90 ° in the first liquid crystal layer 9 and the polarization direction is also twisted by 90 °, which is absorbed by the second-layer magenta color polarizer 23, and enters the second liquid crystal layer 10 as it is. Since the liquid crystal molecules are vertically aligned in the second liquid crystal layer, only the red light is absorbed by the yellow color polarizer 24 in the second layer. As described above, red display can be performed over all picture elements by switching the alignment state of liquid crystal molecules and selecting one of the stacked color polarizers. The same applies to other green and blue monochromatic displays.

Next, the case of displaying red, green, and blue of each of the three picture elements will be described. As shown in FIG. 4, with respect to the picture element on the left side, the first liquid crystal layer 9 is colored red, and the second liquid crystal layer 10 transmits the components other than green with the magenta color polarizer. pass. First about the central picture element
In the second liquid crystal layer, cyan is colored, and in the second liquid crystal layer, only yellow light is absorbed by the yellow color polarizer 24 and passes through.
Regarding the picture element on the right side, the second color polarizer 23 of the first liquid crystal layer is colored magenta, and only the blue light passes through the first color polarizer 21 of the second liquid crystal layer. If these picture elements are made fine enough, they will be observed as white by additive color mixing. The arrows in FIGS. 2 to 4 indicate the paths of light, and are colored in each color by a color polarizer with a black circle in the middle.

<Effects of the Invention> In the conventional methods, in order to perform full-color display, it is necessary to pattern each pixel into red, green, blue or cyan, magenta, and yellow. Specifically, photoresist coating and exposure are performed. The development process and the dyeing process with a dichroic dye must be performed for each color, and the process is very complicated. According to the present invention, since the color polarizer of the first layer or the second layer is composed of two colors, the process can be simplified. In the case of single color display, the display pixel
It can contribute to display up to 3/3, and because it can display black, it can realize a color liquid crystal display with a bright display and excellent display contrast.

[Brief description of drawings]

FIG. 1 is a sectional view showing a cell structure of an embodiment of the present invention, and FIG.
FIGS. 4 to 4 are diagrams for explaining the operation of the embodiment, FIG. 2 shows a black display, FIG. 3 shows a red single color display, and FIG. 4 shows a white display state. FIG. 5 shows a cell structure sectional view of a conventional color liquid crystal display device using a color filter, and FIGS. 6 and 7 show cell structure sectional views of a conventional color liquid crystal display device using a color polarizer. 17 is a liquid crystal molecule, 11, 16 ₁ and 16 ₂ are glass substrates, 22, 23 and 24 are cyan, magenta and yellow color polarizers, 19, 20 and 21 are red, green and blue color polarizers, Indicates red, green, and blue colored light.

Claims (1)

[Claims] 1. A polarization direction of incident polarized light is changed by applying a voltage.
The first is arranged in a stacking relationship that is selectively set to rotate 90 ° or to transmit incident polarized light as it is.
And the second liquid crystal layer, and two color polarizers having different absorption characteristics and mutually orthogonal absorption axis directions from each other.
And a second liquid crystal layer, which is laminated and formed on one side of the first liquid crystal layer, and the polarization direction is orthogonal or parallel to the absorption axis direction of the color polarizer. In a color liquid crystal display device including a child, the color polarizer of the first layer and the color polarizer of the second layer, which are laminated and formed on the first and second liquid crystal layers, have a complementary color relationship with each other. Alternatively, the color polarizer of the second layer has two colors, and the first and second picture elements of the first liquid crystal layer have the same color combination with respect to the adjacent first to third picture elements. The corresponding first picture element and second picture element of the second liquid crystal layer are composed of different color combinations, and further, the third picture element of the first liquid crystal layer and the first picture element of the second liquid crystal layer are First and second picture elements of the first liquid crystal layer and second picture elements of the second liquid crystal layer, which are composed of the same color combination Beauty color liquid crystal display device which is a combination of different color than the third picture element.