JPH0497124A - Color liquid crystal display device - Google Patents

Abstract

PURPOSE:To make a gradational display by forming a display electrode in two-layered structure, and applying voltages to respective electrodes individually and varying the quantity of a voltage applied to a liquid crystal layer by the display electrode. CONSTITUTION:A 2nd segment electrode 26 is laminated and arranged in the same area with a 1st segment electrode 23. The 1st and 2nd segment electrodes 23 and 26 consist of an electrode Sr for red, and electrode Sg for green, and an electrode Sb for blue. The respective electrodes Sr, Sg, and Sb are formed in areas corresponding to filters R, G, and B and the respective electrodes are connected by transparent electrodes as signal lines. The gradations of even the same color are different between a case wherein the voltage is applied to one of the 1st and 2nd segment electrodes 23 and 26 and a case wherein the voltage is applied to both the 1st and 2nd segment electrodes 23 and 26. Consequently, two kinds of gradational display can be made.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a segment type color liquid crystal display device that displays predetermined characters, figures, etc. in color.

BACKGROUND OF THE INVENTION FIG. 7 is a plan view of a conventional segment type liquid crystal display device 230. A plurality of segment electrodes 233 are arranged on the liquid crystal display device 230 so as to form the character "day". Further, a color filter colored red, for example, is provided in the area A1, a green color filter is provided in the area A2, and a blue color filter is provided in the areas A3 to A5.

FIG. 8 is a cross-sectional view of the liquid crystal display device 230.

The liquid crystal layer 237 includes a transparent glass substrate 231a,
231b, and is sealed with a sealing resin 238. A plurality of segment electrodes 233 are formed on the surface of the glass substrate 231a on the liquid crystal layer 237 side, and an alignment film 234a is further formed on the surface.

On the other hand, a plurality of common electrodes 232 are formed on the surface of the glass substrate 231b on the liquid crystal layer 237 side, and an alignment film 234b is further formed on the surface. Glass substrate 23
On the surface of 1a, 231b opposite to the liquid crystal layer 237,
Polarizing plates 235a and 235b are provided, respectively.

The aforementioned red, green, and blue color filters 236 are formed on the polarizing plate 235a in a region including the segment electrodes 8i233 by a printing method or the like.

FIG. 9 is a sectional view showing another configuration of the liquid crystal display device 230. Here, in order to eliminate color shift due to parallax in the display area, the color filter 236 is formed on the common pole 232 by an electrodeposition method, a printing method, or the like.

In such a liquid crystal display device 230, for example, a voltage is applied between the common electrode 232 and the electrode corresponding to the display area to be displayed among the segment electrodes 233 in the area A1. Light passes through the liquid crystal layer corresponding to the segment electrodes, and a red display can be performed. In other areas A2 to A5, green display and blue display can be performed using the same method.

Furthermore, in the liquid crystal display device disclosed in USP-3840695, color filters are arranged on the front and rear surfaces of the liquid crystal display element, and it is possible to display only one color in one unit area.

In general, since liquid crystals have wavelength dependence, the light-shielding properties of the liquid crystal display device 230 are not perfect and cannot block light over the entire visible wavelength range. Therefore, in the liquid crystal display device 230 described above, when performing positive display (background color is white and display color is black), light passes through the liquid crystal layer 237 even when no voltage is applied to the liquid crystal layer 237. Since the area A1 in FIG. 7 mentioned above is colored red and appears to be distinguished from other areas, there is a problem that the display quality of the liquid crystal display device 230 deteriorates. In addition, the display (
If the background color is black and the display color is white), the liquid crystal layer 237
Since the light-shielding property of the color filter 236 is not perfect, the shape of the color filter 236 can be seen through even when no voltage is applied, resulting in a problem of deterioration of display quality.

In addition, the display color of the display area is determined by the color type of the color filter during manufacturing of the liquid crystal display device, so
It is not possible to display the same display area in different colors, resulting in poor display diversity and versatility.

In order to solve the above-mentioned problems, a liquid crystal display device using a fine band-shaped color filter was developed in Japanese Patent Laid-Open No. 60-26092.
1. JP 61-239220, JP 62-0919
It is disclosed in 17.

FIG. 10 is a cross-sectional view of a segment type color liquid crystal display device 301 using a band-shaped color filter. A color filter 305 is provided over almost the entire surface of the transparent glass substrate 304a by a method such as a printing method or an electrode coloring method.
A plurality of segment electrodes 306 are formed on the display area 5 corresponding to a predetermined display area. The color filter 305 is
For example, it is formed in a band shape in a direction parallel to the paper surface of Figure 10,
For example, a plurality of three types of filters, red filters, green filters, and blue filters, are arranged in a predetermined order in a direction perpendicular to the plane of FIG. 10. The segment electrode 306 is composed of a red electrode, a green electrode, and a blue electrode corresponding to the red filter, green filter, and blue filter, respectively.

A plurality of common electrodes 308 are formed on one surface of the light-transmitting glass substrate 304b over an area including the display area corresponding to the segment electrodes 306, and an alignment film 307b is further formed on the surface. Glass substrate 304
a and 304b are arranged such that the surfaces on which the alignment films 307a and 307b are formed face each other. The rye stained nematic liquid crystal layer 30 is a glass substrate 304a3.
04b and is sealed with a sealing resin 310. Furthermore, polarizing plates 311.
312 is provided.

Here, the polarizing plates 311 and 312 are arranged so as to form crossed nicols so that light does not pass through the liquid crystal layer 309 when no voltage is applied, thereby performing a so-called normally black display. By applying a voltage to a desired electrode among the three electrodes constituting the segment electrode 306, a desired color is displayed in the display area corresponding to the segment t8i306. For example, if voltage is applied only to the red electrode, red will be displayed in the display area, and if voltage is applied to the red and green electrodes at the same time, yellow will be displayed due to the mixture of red and green light. It can be performed.

Furthermore, white display can also be performed by simultaneously applying voltage to all the electrodes: the red electrode, the green electrode, and the blue electrode.

Problems to be Solved by the Invention The color liquid crystal display device 301 described above has transparent electrodes formed corresponding to three color filters, for example, a red filter, a green filter, and a blue filter, formed within a predetermined display area. By selecting the transparent electrode to which voltage is applied, up to eight colors can be displayed.

However, each display color is only displayed in the same gradation,
The variety of display colors was limited, and the variety of display was poor.

An object of the present invention is to provide a color liquid crystal display device that can perform gradation display.

Means for Solving the Problems The present invention comprises a pair of light-transmitting substrates provided with a liquid crystal layer in between, and a plurality of light-transmitting substrates provided over almost the entire surface of one surface of the light-transmitting substrates on the liquid crystal layer side to predetermine transmitted light. a plurality of color selection members each selecting one of the different colors; and a plurality of color selection members provided on the liquid crystal layer side of the transparent substrate and formed for each of the plurality of color selection members within a predetermined display area. a display electrode having a translucent property, the display electrode having a two-layer structure,
The color liquid crystal display device is characterized in that the amount of voltage applied to the liquid crystal layer by the display electrodes is changed by applying a voltage to each electrode individually.

Function According to the present invention, normally black display with a black background can be performed by preventing light from passing through the color liquid crystal display device when no voltage is applied. Here, the display electrode is formed corresponding to a predetermined shape, and is formed corresponding to each of the plurality of color selection members.

By applying a voltage to this display electrode, light can be transmitted through the liquid crystal layer. This transmitted light is selected as one predetermined color by the color selection member, and the predetermined shape corresponding to the display electrode is displayed on the color liquid crystal display device using the predetermined color.

At this time, a voltage is applied to each display electrode formed individually corresponding to a plurality of types of color selection members, and further different colors are displayed by combining a plurality of types of colors selected by the color selection members. I can do it.

In addition, since the color selection member is provided over the entire surface of the transparent substrate, even if there is light leakage from the liquid crystal layer when no voltage is applied to the display electrodes, the color liquid crystal display device can The same color, that is, a color that is a combination of colors selected by each color selection member, is displayed over the entire surface, and only a portion is prevented from being displayed in a different color, thereby improving display quality.

In the above-described normally black display, by applying a voltage equal to or higher than a predetermined threshold voltage to the liquid crystal layer, the liquid crystal layer transmits light. It is known that increasing the amount of voltage applied to a liquid crystal layer increases the transmittance of light passing through the liquid crystal layer. In the present invention, the display electrode has a two-layer structure, and by applying a voltage to each electrode individually, the amount of voltage applied to the liquid crystal layer is changed in stages, and the transmittance of light passing through the liquid crystal layer is gradually changed. It is possible to change it to Therefore, even if the color is the same, it is possible to create brighter gradations by increasing the transmittance.
Further, by reducing the transmittance, a dark gradation can be achieved. In this way, the same color can be displayed in a plurality of gradations, the variety of display colors increases, and the diversity of display can be improved.

Embodiment FIG. 1 is a sectional view of a color liquid crystal display device 21 which is an embodiment of the present invention. The color liquid crystal display device 1m21 is
Transparent substrates 22a, 2 made of glass, plastic, etc.
2b, and a transparent electrode (first segment electrode) is provided on one surface of the transparent substrate 22a in an area corresponding to the shape to be displayed.
23 is formed. Furthermore, the first segment electrode 2
A color filter 24 is formed on the transparent substrate 22a on which the color filter 3 is formed. The color filter 24 is composed of, for example, three color filters arranged in a matrix, such as a red filter, a green filter, and a blue filter, and a black light shielding layer, and is formed by a printing method or the like on almost one surface of the transparent substrate 22a. It is formed over the entire surface.

The surface of the color filter 24 is provided with a second segment electrode 26, which will be described later, to reduce the unevenness of the surface of the color filter 24.
to prevent the deterioration of the color filter 24 during the formation of the second
An overcoat layer 25 is formed to improve the adhesion of the segment electrodes 26. After forming the overcoat layer 25, a transparent electrode (second
The segment t&) 26 is connected to the first segment t&23.
It is formed in an area corresponding to the same shape as . Furthermore, an alignment film 27a is formed on the surface.

A transparent electrode (common electrode) is provided on one surface of the transparent substrate 22b.
! f 28 or at least the first segment electrode 23
and formed in a region including the second sector electrode 26,
Furthermore, an alignment film 27b is formed on the surface.

The transparent substrates 22a and 22b are provided with alignment films 27a and 2, respectively.
The surfaces 7b formed thereon are arranged so as to face each other. Two liquid crystal layers are interposed between transparent substrates 22a and 22b,
It is sealed with a sealing material 30.

Polarizing plates 31 and 32 are arranged on the opposite surfaces of the transparent substrates 22a and 22b from the two liquid crystal layers, respectively.

For the alignment films 27a and 27b, polyimide resin (trade name: rPIQj, manufactured by Hitachi Chemical Co., Ltd.) was used.

The alignment films 27a and 27b are formed to have a layer thickness of, for example, 600 mm, and are made of nylon thread woven fabric so that the alignment direction of liquid crystal molecules is twisted by 90° between the transparent substrates 22a and 22b, forming a levorotatory liquid crystal layer, for example. Rubbed.

In order to keep the distance between the transparent substrates 22a and 22b constant,
A plastic spacer (not shown) is sandwiched between these substrates. With this spacer, the distance between the substrates is set to, for example, 5 μm. The sealing material 30 for sealing the two liquid crystal layers is, for example, epoxy resin (manufactured by Mitsui Toatsu Co., Ltd.). For the two liquid crystal layers, for example, a phenylcyclohexane mixed liquid crystal is selected. Furthermore, cholesteric nonenoate is added to this liquid crystal, giving it levorotatory properties.

Furthermore, for the orientation [27a, 27b, the transparent substrate 22a,
The orientation direction of the liquid crystal molecules is twisted by 90° between 22b,
A rubbing treatment may be performed to form a dextrorotatory liquid crystal layer. In this case, a phenylcyclohexane-based mixed liquid crystal to which CB-15 (manufactured by Merck & Co., Ltd.) is added as a dextrorotatory chiral substance is used for the two liquid crystal layers.

FIG. 2 is a plan view of the color liquid crystal display device 21. FIG. As shown in FIG. 2, for example, the first segment electrode 23 is formed in a rectangular shape, and seven of the first segment electrodes 23 formed in the rectangular shape are used to form the character "日". For example, two characters of "日" are placed side by side.

Further, the second segment electrode 26 is connected to the first segment electrode 2
They are stacked and arranged in the same area as No. 3.

FIG. 3 is an enlarged plan view of the color filter 24, and the fourth
The figure is an enlarged sectional view of the vicinity of the color filter 24. In the color liquid crystal display device 21, a color filter 24, which is a color selection member, is provided over almost the entire surface of a transparent substrate 22a. The color filter 24 is formed by arranging red, green, and blue filters in a matrix or mosaic pattern.

In FIGS. 3 and 4, red filters are designated with reference number R, green filters are designated with reference number G, and blue filters are designated with reference number B. The sizes of filters R, G, and H are so minute that they cannot be discerned with the naked eye.

As an example, length L1=330μm and width L2-80
.mu.m rectangular filters R, G, and B are used, and the spacing L3 between each filter is selected to be 30 .mu.m. therefore,
Three types of filters R, G lined up in the width direction R2 of the filter,
The area formed by B is 330 μm x 330 μm
becomes a square.

The spacing L3 between the filters is determined by the manufacturing accuracy of color filters such as photoprocessing, and is generally 15 μm to 15 μm.
It is 40 μm.

In the arrangement of the filter, for example, an R-G-B permutation is repeated in the width direction R2 of the filter, and an R-B-G permutation is repeated in the length direction R1 of the filter. Filter R
, G, and B may be square or other shapes.

In addition, between each filter R, G, B, there is a black light shielding layer B.
L is formed. The light shielding layer BL is formed of chromium (Cr), black pigment, or the like.

Figure 5 is the first segment! 8ii23 is an enlarged plan view. As mentioned above, on the transparent substrate 22a, there are rectangular color filters R, G, B in three colors of red, green, and blue.
The present invention provides a color liquid crystal display device 21 in which transparent electrodes are arranged as signal lines so that segments corresponding to color filters of the same color are sequentially connected with poles. It is.

The first sector electrode 23 includes a red chamber isr, a green electrode Sg, and a blue electrode sb. Electrodes Sr, Sg, S
b are formed in regions corresponding to the filters R and GB, respectively, and the electrodes Sr and 5g5b are respectively connected by transparent electrodes 41r, 41g and 41b as signal lines.

Using this connection method, red, yellow, green,
Seven colors, light blue (cyan), blue, white, and pink (magenta), can be displayed within a desired display area. The second segment electrode 26 also has the same configuration as the first segment electrode 23.

FIG. 6 is a block diagram showing the electrical configuration of the color liquid crystal display device 21. A backlight 43 is arranged on the opposite side of the polarizing plate 32 from the liquid crystal element. By transmitting/blocking the light using the color liquid crystal display device 21, a plurality of colors as described below are displayed on the color liquid crystal display device 21. The liquid crystal element is driven by a liquid crystal element drive circuit 45.
controlled by The liquid crystal element drive circuit 45 applies a voltage to the common electrode 28 via the signal line β1 based on the display control signal from the display control circuit 46, and applies a voltage to the selected first segment electrode 23 via the signal line group 12. A voltage is applied to the selected second segment electrode 26 via the signal line group 13. As a result, color display can be performed in the color liquid crystal display device 21.8 Also, even if the colors are the same, a voltage is applied to only one of the first and second segment electrodes 23 and 26. Since the brightness gradation is different when voltage is applied to both the first and second segment voltages 123.26, two types of gradation display can be performed. therefore,
A maximum of 27 colors can be displayed.

A case will be described in which so-called normally white display and normally black display are performed in the color liquid crystal display device 21 described above. Here, the liquid crystal molecules of the liquid crystal layer 29 are such that the molecules closest to the transparent substrate 22b are aligned in a direction perpendicular to the plane of the paper in FIG. It is assumed that the liquid crystal molecules closest to the substrate 22a are aligned in a direction parallel to the plane of the paper in FIG.

■Normally white display Normally white display means that when no voltage is applied, light passes through the liquid crystal layer 29 so that, for example, the background color is white, and the liquid crystal layer is in the area corresponding to the shape to be displayed. This is a display method in which a desired shape is displayed by applying a voltage to 29 to change the alignment state of liquid crystal molecules, thereby blocking light. Therefore, the polarizing directions of the polarizing plates 31 and 32 are set to be orthogonal Nicols, for example, the polarizing direction of the polarizing plate 32 is set perpendicular to the plane of the first drawing, and the polarizing direction of the polarizing plate 31 is set parallel to the plane of the first drawing. Arrange it so that As a result, the light that has passed through the polarizing plate 32 is twisted by 90° by the liquid crystal layer 29 and is no longer transmitted through the polarizing plate 31.

At this time, the color filter 24 is formed by fine rectangular filters R, G, and B as shown in FIG. becomes. That is, when no voltage is applied, the color liquid crystal display device 21 displays white as the background color. The liquid crystal molecules in the two liquid crystal layers to which a voltage is applied are aligned in the direction of the electric field. Therefore, the linearly polarized light in the direction perpendicular to the plane of FIG. 1, which has passed through the polarizing plate 31, passes through the two liquid crystal layers in almost the same polarized state. Here, since the polarization direction of the polarizing plate 31 is parallel to the plane of FIG. 1, the light transmitted through the liquid crystal layer 29 cannot be transmitted through the polarizing plate 31.

The liquid crystal layer 29 has voltage application (ON)/non-voltage application (OFF).
) acts as a light shutter. In Table 1 below,
The relationship between the 0N10 FF state of the segment electrode, the function of the liquid crystal layer as a light shutter, and the displayed color is shown.

In Table 1, "○" indicates the oven state of the optical shutter, and "." indicates the closed state of the optical shutter.

Table 1 - Normally black display Normally blank display means that the background color is black so that light does not pass through the two liquid crystal layers when no voltage is applied, and a voltage is applied to the liquid crystal layer 29. This is a display method that allows light to pass through and displays a desired shape. Then, the polarizing plate 3132 is arranged so that the polarization direction is parallel Nicols. That is, the polarizing plates 31 and 32 may be arranged so that the polarization directions are perpendicular to the plane of the paper in FIG.
Alternatively, they may be arranged parallel to the plane of FIG. 1. As a result, light cannot pass through the two liquid crystal layers when no voltage is applied. Therefore, black is displayed as the background color on the color liquid crystal display device 21.

The two liquid crystal layers function as optical shutters by applying/not applying voltage, as in the above-described normally white display. Table 2 below shows segment electrodes 0N10FF.
The relationship between the state, the function of the liquid crystal layer as a light shutter, and the displayed color is shown.

In Table 2, 'OJ' indicates the oven state of the optical shutter, and '.' indicates the closed state of the optical shutter.

Table 2 Regardless of whether a normally white display or a normally black display is performed, there is a case where a voltage is applied to both the first and second segment electrodes 23.26, and a case where a voltage is applied to both the first and second segment electrodes 23.26. 26, the voltage applied to the two liquid crystal layers changes.

As a result, the transmittance of light passing through the liquid crystal layer 29 can be changed, and even if the colors are the same, colors with different brightness gradations can be displayed.

As described above, according to this embodiment, in addition to the 8-color display, 27-color display can be performed by changing the brightness gradation. This improves display diversity and allows the color liquid crystal display device 21 to display rich colors.

In addition, by arranging the color filters in a matrix or mosaic pattern, when multiple types of color filters with different colors are combined to display different colors, the degree of mixing and clarity of the displayed colors when viewed visually is significantly improved. This improves display quality.

In this embodiment, although the first and second segment electrodes 2B and 26 are formed with the color filter 24 interposed in the transparent substrate 22a on which the color filter 24 is formed, the common electrode 12 on the opposite transparent substrate 22b side is
Even if 8 has a two-layer structure with an insulating film such as silicon nitride or silicon oxide interposed therebetween, gradation display can be performed in the same manner as in the above embodiment.

Further, in this embodiment, the common electrode 28 is formed larger than the first and second segment electrodes 23 and 26 formed on the transparent substrate 22a, so that electrode portions not related to display are not lit. Second segment electrode 2
Although the design is such that no matter which electrode in 3.26 a voltage is applied, a voltage higher than the threshold voltage will not be applied to any part other than the necessary part. The gradation display may be performed using the electrodes.

In this example, twisted nematic liquid crystal in which the twist angle of liquid crystal molecules is 90° is used as the two liquid crystal layers, but super twisted nematic liquid crystal in which the twist angle is 180° to 270° may also be used. .

Effects of the Invention As described above, according to the present invention, the same display area can be displayed in different colors and in different gradations, and the diversity of display can be improved.

[Brief explanation of drawings]

FIG. 1 shows a color liquid crystal display device 2 which is an embodiment of the present invention.
1, FIG. 2 is a plan view of the color liquid crystal display device 21, FIG. 3 is an enlarged plan view of the color filter 24, FIG. 4 is an enlarged sectional view of the vicinity of the color filter 24, and FIG. 5 is a plan view of the segment electrode. Enlarged plan view, Figure 6 shows color liquid crystal display device 2
7 is a plan view of a conventional liquid crystal display device 230, FIG. 8 and FIG. 9 are cross-sectional views of a conventional liquid crystal display device 230, and FIG. 10 is a conventional color liquid crystal display device 230. 3 is a cross-sectional view of a display device 301. FIG. 21... Color liquid crystal display device, 22a, 22b, transparent substrate, 23... First segment electrode, 24... Color filter, 26... Second segment electrode, 28... Common electrode, two...・Liquid crystal layer, 45...Liquid crystal element drive circuit, 46・Display control circuit

Claims (1)

[Scope of Claims] A pair of light-transmitting substrates provided with a liquid crystal layer sandwiched therebetween, and a light-transmitting substrate provided over almost the entire surface of one side of the light-transmitting substrate on the liquid crystal layer side, and having a color selected from among a plurality of colors that predetermine transmitted light. a plurality of color selection members each selecting one of the colors; and a plurality of color selection members provided on the liquid crystal layer side of the translucent substrate, each of which has a translucent property formed for each of the plurality of color selection members within a predetermined display area. a display electrode having a two-layer structure,
A color liquid crystal display device characterized in that the amount of voltage applied to the liquid crystal layer by the display electrodes is changed by applying a voltage to each electrode individually.