JPH0455827A - Color liquid crystal display device - Google Patents

Abstract

PURPOSE:To diversify displaying by making optical compensation by the positional relations between the twist directions of the liquid crystal molecules of respective liquid crystal layers and the orientation directions of liquid crystal molecules in extreme proximity to each other. CONSTITUTION:The twist directions of the liquid crystal molecules of two color liquid crystal element parts 23, 24 are set as to be reversed from each other. The orientation direction of the liquid crystal molecules nearest the transparent substrate 22 of the liquid crystal layer 30 and the orientation direction of the liquid crystal molecules nearest the transparent substrate 22 of the liquid crystal layer 36 are so disposed as to interest orthogonally with each other. Further, polarizing plates 38, 39 are so disposed as to be crossed nicols. The optical compensation is made by positional relations between the twist directions of the liquid crystal molecules of the respective liquid crystal layers and the orientation directions of the liquid crystal molecules in extreme layers and the orientation directions of the liquid crystal molecules in extreme proximity to each other. The display of two kinds of display images with different colors is executed in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a color liquid crystal display device capable of displaying 2N type display images by having a two-layer liquid crystal layer structure.

Conventional technology JP-A-60-260921, JP-A-61-239220
, Japanese Patent Laid-Open No. 61-091917 discloses a segment type color liquid crystal display device in which a stripe-shaped color filter is formed over almost the entire surface of the display screen.

In this color liquid crystal display device, it is possible to select either normally white display or normally black display by changing the arrangement of the polarizing plate, but in the case of normally black display, the incident light is The optical rotation dispersion phenomenon inside the liquid crystal layer causes elliptically polarized light, which causes leakage light that passes through the liquid crystal layer even when no voltage is applied, reducing the contrast of the display screen.

A two-layer liquid crystal display device has been developed as a solution to the above-mentioned decrease in contrast (Japanese Patent Publication No. 6B-535
28, Japanese Patent Publication No. 63-234225).

The two-layer liquid crystal display device disclosed herein is constructed by stacking two liquid crystal elements in which liquid crystal molecules are aligned in a twisted nematic manner.One liquid crystal display element is a display liquid crystal element, and the other liquid crystal element is a display liquid crystal element. The element is a compensating liquid crystal element for returning the elliptically polarized light to linearly polarized light.

FIG. 11 is a sectional view of a conventional two-layer liquid crystal display device 1. As shown in FIG. The liquid crystal display device 1 includes a display liquid crystal element 2 and a compensation liquid crystal element 3. The display liquid crystal element 2 includes a pair of transparent substrates 4a and 4b made of glass, acrylic, or the like.
A color filter 5 is provided on one surface of the transparent substrate 4a.
is provided over almost the entire surface, and the color filter 5
A plurality of segment electrodes 6 having translucency are formed thereon. Furthermore, an alignment film 7a is formed on the segment electrodes 6 and the color filter. The color filter 5 consists of, for example, band-shaped three-color filters extending parallel to the plane of FIG. 11, such as a red filter, a green filter, and a blue filter.

On one surface of the transparent substrate 4b, a plurality of common electrical conductors having translucent properties are arranged. On the transparent substrate 4b on which the fK8 and the common electrode 8 are formed, an orientation M 7 b is formed. The transparent substrates 4a and 4b are arranged so that the surfaces on which the orientations 1117a and 7b are formed face each other, and the twisted nematic liquid crystal 9 is interposed between the transparent substrates 4a and 4b and sealed with a sealing resin 10.

The compensation liquid crystal element 3 has transparent substrates 11a and llb made of glass, acrylic, etc.
Alignment films 12a and 12'b are formed on one surface of the substrate, respectively. The transparent substrates 11a, 11b have an orientation M12a, 1
The twisted nematic ink liquid crystal 13 is placed on the transparent substrate 11a, and the twisted nematic ink liquid crystal 13 is arranged so that the surfaces on which 2b are formed face each other.
, llb, and are sealed with a sealing resin 14.

The display liquid crystal element 2 and the compensation liquid crystal element 3 are connected to a transparent substrate 4.
a and a transparent substrate 11b are stacked so as to overlap, a polarizing plate 15 is arranged on the surface of the transparent substrate 4b opposite to the liquid crystal layer 9, and a polarizing plate 15 is arranged on the surface of the transparent substrate 11a opposite to the liquid crystal layer 13. A polarizing plate 16 is arranged.

The liquid crystal layers 9 and 13 are arranged so that the orientation directions of the liquid crystal molecules closest to each other are perpendicular to each other, and the twist directions of the liquid crystal molecules in the respective liquid crystal layers are opposite to each other. The polarizing plates 15 and 16 are arranged so as to form crossed Nicols.

Problems to be Solved by the Invention In the above-mentioned segment type color liquid crystal display device, since it is a segment display, predetermined colors and display images (shape)
It could only be displayed as , and there was a lack of diversity in display.

In order to improve the diversity of this display, the color display liquid crystal device 2 shown in FIG. By forming them into different shapes, two types of display images can be displayed on one color liquid crystal display device. However, in such a liquid crystal display device, moire fringes occur because two color filter layers are laminated. Moire fringes are rough patterns created by overlapping two regular patterns.

In addition, the color filter layer 5 is formed by band-shaped three-color filters (red filter, green filter, and blue filter) with widths that cannot be discerned with the naked eye, and the segment electrodes 6
Although it is possible to display one display image in different colors by forming them in correspondence with each filter, when displaying a combination of multiple colors, the mixing degree and There is a problem that the clarity of colors decreases and the display quality deteriorates.

An object of the present invention is to provide a color liquid crystal display device in which display diversity and display quality in color display are improved.

Means for Solving the Problems The present invention includes: a first light-transmitting substrate; and one of a plurality of colors provided over the entire surface of one surface of the first light-transmitting substrate to predetermine transmitted light. a plurality of color selection members each selecting one color; a second light-transmitting substrate disposed on one surface side of the first light-transmitting substrate; and a second light-transmitting substrate interposed between the first and second light-transmitting substrates. a first liquid crystal layer formed within a predetermined display area on the first liquid crystal layer side and formed in a range corresponding to the plurality of color selection members selected in accordance with a predetermined color to be displayed in the display area; a third transparent substrate disposed on the other surface side of the first transparent substrate; and a second liquid crystal layer interposed between the first and third transparent substrates. , a second transparent electrode provided within a predetermined display area on the second liquid crystal layer side and formed in a range corresponding to the plurality of color selection members selected in accordance with a predetermined color to be displayed in the display area; A color liquid crystal display device comprising:

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, corresponding to the predetermined shape of the first transparent electrode,
And formed corresponding to the color selection member of the desired color, this first transparent! Light can be transmitted through the first liquid crystal layer by applying a voltage to the poles. This transmitted light is selected as one predetermined color by the color selection member, and thereby the shape and predetermined color corresponding to the first transparent electrode are displayed on the liquid crystal display device.

Further, by forming the second transparent electrode in a shape different from the predetermined shape and corresponding to the desired color selection member, the liquid crystal display device can have a shape different from the predetermined shape as in the case of the first transparent electrode. Different shapes are displayed.

At this time, further different colors can be displayed by forming the first and second transparent electrodes individually corresponding to multiple types of color selection members and combining multiple types of colors selected by the color selection members. can.

Furthermore, the transmitted light becomes elliptically polarized light by passing through the first liquid crystal layer corresponding to the first transparent electrode to which no voltage is applied and the first liquid crystal layer corresponding to the area where the first transparent electrode is not formed. , when transmitting through the second liquid crystal layer, the liquid crystal molecules are oriented in the opposite direction to the liquid crystal molecules in the first liquid crystal layer, so the light is rotated in the opposite direction. Since the extraordinary light component and the normal light component of the polarized light incident on the liquid crystal layer are arranged so that the closest liquid crystal molecules are orthogonal to each other, the elliptically polarized light is canceled out and returned to linearly polarized light by exchanging each other.

Therefore, the light transmitted through the area where the first transparent electrode is not formed and the area corresponding to the first transparent electrode to which no voltage is applied is completely compensated by the second liquid crystal layer.
Light leakage can be prevented. As a result, it is possible to display complete black without coloring, and it is possible to improve the contrast in so-called normally black mode in which the background color is black.

In this way, a plurality of different display images (shapes) can be displayed in different colors, and display diversity can be obtained.

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 21 has two twisted nematic mode liquid crystal display element parts, a first color display element part 23 and a second color display element part 24, each including a transparent substrate 22. The transparent substrate 22 is made of, for example, PES (polyether sulfone), PET (polyether terephthalate), polyarylate, or polycarbonate, and has a thickness of, for example, 0.1 mm.

The first color display element section 23 has the transparent substrate 22 and a transparent substrate 25 made of glass, acrylic, etc., and a color filter layer 26 is provided on one surface of the transparent substrate 22 over almost the entire surface. A plurality of light-transmitting segment electrodes 27 are formed on the color filter layer 26, and an alignment film 28a is further formed on the color filter layer 26 on which the segment electrodes 27 are formed. Transparent substrate 2
5, at least the segment electrode 27
A light-transmitting common electrode 29 is formed over a region including the substrate, and an alignment film 28b is further formed on the common electrode 29. The transparent substrates 22, 25 are arranged such that the surfaces on which the oriented WAs 28a, 28b are formed face each other. The twisted nematic liquid crystal layer 30 is interposed between the transparent substrates 22 and 25 and sealed with a sealant 31.

The alignment films 28a and 28b are made of polyimide resin, for example. The alignment films 28a and 28b are formed to have a layer thickness of, for example, 600 mm, and are rubbed with a nylon thread fabric so that the alignment direction of liquid crystal molecules is twisted 90 degrees between the transparent substrates 2225, forming a levorotatory liquid crystal layer. has been done.

In order to maintain a constant distance between the transparent substrates 22 and 25, a plastic spacer (not shown) is inserted between these substrates. With this spacer, the distance between the substrates is set to, for example, 5 μm. The sealing material 31 for sealing the liquid crystal layer 30 is, for example, epoxy resin. For the liquid crystal layer 30, for example, a phenylschiffhexane mixed liquid crystal is selected. Furthermore, cholesteric nonenate is added to this liquid crystal, giving it levorotatory properties.

The second color display element section 24 has the transparent substrate 22 and a transparent substrate 32 made of glass, acrylic, etc., and the other surface of the transparent substrate 22 corresponds to a predetermined shape to be displayed in the display area. A plurality of light-transmitting segment electrodes 33 are formed over the range, and an alignment film 34a is formed on the other surface of the transparent substrate 22 on which the segment electrodes fi 33 are formed. A common electrode 35 having a light-transmitting property is formed on one surface of the transparent substrate 32 over an area including at least the segment electrode 33,
On the transparent substrate 32 on which the common electrode 35 is formed, there is an orientation M.
34b is formed. The transparent substrate 22.32 has an orientation M3
The surfaces 4a and 34b formed thereon are arranged so as to face each other. The twisted nematic liquid crystal layer 36 is interposed between the transparent substrates 22 and 32 and sealed with a sealant 37.

The alignment films 34a and 34b are made of polyimide resin or the like, and are rubbed so that the alignment directions of the liquid crystals are twisted by 90 degrees between the transparent substrates 22 and 32 to form a dextrorotatory liquid crystal layer. .

The liquid crystal layer 36 uses a phenylcyclohexane mixed liquid crystal as in the first color display element section 23 described above.
-15 (manufactured by Merck & Co.) is added. Transparent substrate 22
．． In order to keep the distance between the substrates 32 constant, a plastic spacer was sandwiched between these substrates, as in the case of the first color display element section 23 described above, and the substrates were overlapped.

The spacing between the transparent substrates 22, 32 is chosen to be, for example, 5 μm.

A polarizing plate 3839 is arranged on the surface of the transparent substrate 25.32 opposite to the surface facing the transparent substrate 22.9 segment electrodes 27.33 and common electrodes 29.35
is formed of ITO. The sheet resistance value of ITO is 20~
A medium resistance value of 50Ω/portion is generally used, but a low resistance value or a resistance value of 100Ω/portion or more may also be used.

FIG. 2 is a plan view of the color liquid crystal display bag w21. In this embodiment, a case where numbers and a level meter are displayed on the color liquid crystal display device 21 will be described. Above the display area of the color liquid crystal display device 21, seven segment electrodes 27 formed in, for example, a rectangular shape are arranged to form the characters "1 day", and such characters "day" are arranged, for example, to form the characters "2 days". They are lined up.

Below the display screen of the color liquid crystal display device 21, for example, six segment electrodes 33 formed in a band shape are arranged in parallel.

FIG. 3 is an enlarged plan view showing the structure of the color filter layer 26, and FIG. 4 is a sectional view showing the structure of the color filter layer 26. The color filter layer 26 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 each of the filters R, G, and B are so small that they cannot be discerned with the naked eye.

- As an example, length LL = 330 μm and width L2 = 80
A1m rectangular filters R, G, and B are used, and the interval L3 between the filters is selected to be 30 μm. therefore,
Three types of filters R, G lined up in the filter width direction A2,
The area formed by B is 3308m x 330μm
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.

The filter arrangement is R-(,
-B permutation is repeated, and in the length direction A1 of the filter, R
-The BG permutation is repeated. The shapes of the filters R, G, and B may be square or other shapes.

Moreover, between each filter R, G, and B, a black light shielding layer 40 is provided.
is formed. The light shielding layer 40 is made of chromium (Cr), black pigment, or the like.

In this embodiment, the color filter layer 26 is formed by filters R, G, and H of three colors, red, green, and blue, but the color filter layer 26 is formed after selecting two desired colors from the three colors. Furthermore, the filters are not limited to the three colors of red, green, and blue, but may be filters of yellow, magenta, cyan, or the like. In this case as well, a two-color filter may be used as described above. Furthermore, the color filter layer 26 may be formed using filters of four or more colors.

FIG. 5 is an enlarged plan view of the segment electrode 27. The segment electrode 27 includes an electrode Sr for red color and a pole Sr for green color.
g, and a blue electrode sb. Electrode Sr, Sg
, Sb are formed in the respective areas corresponding to the filters R, G, H in the display area, and each type aisr, Sg, Sb
are transparent electrodes 41r, 41g, 41b as signal lines
are connected to each other by. In this way, by sequentially connecting the electrodes Sr, Sg, and Sb corresponding to filters of the same color and arbitrarily selecting the electrode to which voltage is applied,
Seven colors, red, yellow, green, light blue (cyan), blue, white, and pink (magenta), can be displayed within the target display area. The segment electrode 33 also
It has the same configuration as the segment electrode 27.

FIG. 6 shows the polarizing plate 38 in the color liquid crystal display device 21.
．． 39 and the orientation direction of liquid crystal molecules in twisted nematic liquid crystal layers 30 and 36. FIG. FIG. 6(1) shows absorption axes R1 of three polarizing plates. FIG. 6(2) shows the second color display element section 24.
The orientation direction and twist direction of liquid crystal molecules in the liquid crystal layer 36 are shown. The alignment direction of the liquid crystal molecules closest to the transparent substrate 32 is indicated by an arrow R2, and this alignment direction R2 is parallel to the absorption axes R1 of the three polarizing plates. Further, the alignment direction of the liquid crystal molecules closest to the transparent substrate 32 is indicated by an arrow R3, and therefore the liquid crystal molecules of the liquid crystal layer 36 are oriented 90° to the right.
It's twisted.

FIG. 6(3) shows the liquid crystal layer 3 of the second color display element section 23.
The orientation direction and twist direction of the liquid crystal molecules of 0 are shown.

The orientation direction of the liquid crystal molecules closest to the transparent substrate 22 is indicated by the arrow R.
4, and the alignment direction of the liquid crystal molecules closest to the transparent substrate 25 is indicated by an arrow R5. Therefore, the liquid crystal molecules of the liquid crystal layer 39 are twisted 90 degrees to the left. FIG. 6(4) shows an absorption axis R6 of the polarizing plate 38, and this absorption axis R6 is parallel to the alignment direction R5 of the liquid crystal molecules closest to the transparent substrate 25.

As shown in FIG. 6, the twist angles of the liquid crystal molecules in the liquid crystal layer 30 of the first color display element section 23 and the liquid crystal layer 36 of the second color display element section 24 are both 90 degrees. Furthermore, the liquid crystal molecules in the liquid crystal layer 30 are oriented levorototally, and the liquid crystal molecules in the liquid crystal layer 36 are oriented dextrorotally. That is, in the two liquid crystal element sections 23 and 24, the twist directions of the liquid crystal molecules are set to be opposite to each other. Furthermore, the liquid crystal layer 30
The alignment direction of the liquid crystal molecules closest to the transparent substrate 22 of the liquid crystal layer 36 and the alignment direction of the liquid crystal molecules closest to the transparent substrate 22 of the liquid crystal layer 36 are arranged to be orthogonal to each other. Further, the polarizing plates 38 and 39 are arranged in crossed Nicols.

In a two-layer liquid crystal display device, optical compensation can be performed depending on the twist direction of the liquid crystal molecules in each liquid crystal layer and the positional relationship between the orientation directions of the liquid crystal molecules closest to each other.

Table 1 below shows the positional relationship between the twist direction and the alignment direction, and the effects associated therewith.

Table 1 In this example, in order to give priority to optical compensation,
A state is used in which the twist directions of the liquid crystal molecules are opposite, and the alignment directions of the liquid crystal molecules closest to each other are perpendicular to each other.

FIG. 7 is a block diagram showing the electrical complement of the color liquid crystal display device t21. A backlight 43 is disposed on the opposite side of the polarizing plate 35 from the first color display element section 23, and the light from the backlight 43 is transmitted/blocked by the first and second color display element sections 23.24. ,
A display screen as described later is displayed on the color liquid crystal display device 21. The first color display element section 23 is controlled by a first color display element drive circuit 45. The first color display element drive circuit 45 applies a voltage to the two common electrodes via the signal line 11 based on the display control signal from the display control circuit 47, and applies a voltage to the selected segment via the signal line group 12. A voltage is applied to the I-electrode 27. The second color display element section 2 4 is driven by a second color display element drive circuit 46 . The second color display element drive circuit 46 applies a voltage to the common electrode 35 via the signal line 13 based on the display control signal from the display control circuit 47, and applies a voltage to the signal line ! ! A voltage is applied to the selected segment electrode 33 via ¥14.

FIG. 8 is a timing chart for explaining the driving state of the color liquid crystal display device 21, and FIG. 9 is a diagram showing a display example of the color liquid crystal display device 21. FIG. 8(1) shows the driving state of the first color display element section 23,
A high level indicates when voltage is applied, and a low level indicates when no voltage is applied.

FIG. 8(2) shows the driving state of the second color display element section 24, where a high level represents when voltage is applied, and a low level represents when no voltage is applied.

In period TI, display is performed only by the first color display element section 23, so as shown in FIG. 9(1), "
Only the characters ``日'' are displayed. During the period T2, since the display is performed only in the second color display element section 24,
As shown in FIG. 9(2), only the level meter is displayed.

During period T3, the first and second color display element sections 23.
24, the two characters "day" and the level meter are displayed, as shown in FIG. 9(3).

(The following is a margin) Table 1 Table 1 shows the first and second color display element portions 23.2.
4 shows the correspondence between the drive states and display colors. The segment electrodes 27.33 are composed of a red electrode Sr, a green electrode Sg, and a blue electrode sb, which correspond to the three color filters R, G, and B, respectively, as shown in FIG. 5 described above. The liquid crystal layer corresponding to each electrode Sr, Sg, and Sb functions as a light shutter. "○" indicates when voltage is applied, "・
” indicates when no voltage is applied.

Therefore, by applying voltages to desired electric currents fisr, sg, and Sb, a seven-color display can be performed. In this case, the display colors of the normal display and the normal display 41 to 41 are different even if they are in the same driving state. In other words, even if the normally black display and normally white display are in the same driving state,
The display colors have a mutually complementary relationship.

FIG. 10 is a diagram showing viewing angle characteristics of the color liquid crystal display device 21. FIG. 10 shows viewing angle characteristics when the color liquid crystal display device 21 performs normally black display. In FIG. 10 (1), the solid line 110 is surrounded by J.
The contrast ratio CO is a region of 10 or more, and FIG. 10 (1) shows the viewing angle characteristics when display is performed by the second color display element section 24.

FIG. 10 (2) shows the viewing angle characteristics when display is performed by the first color display element section 23, and the area surrounded by the solid line 111 is an area where the contrast l-ratio Co is 10 or more. .

As described above, according to this embodiment, the color liquid crystal device 21
Since it has a two-layer structure, two types of display images can be displayed, and display diversity is realized.

Transparent substrate 22 used in color liquid crystal display device 21
has a thickness of 0.1 mm, and because it is thin, there is no misalignment due to parallax between the filter layer 26 and the electrode in the first and second color display element parts 23 and 24, and the color filter layer is even thicker. Therefore, clear color display can be performed without the occurrence of moiré fringes.

In addition, since the color filter layer 26 is composed of fine square filters R, G, and B arranged in a matrix, when different types of filters are combined to display different colors, it is possible to The degree of mixing and the clarity of displayed colors are improved, allowing beautiful colors to be displayed. 2, and the display quality is greatly improved.

Note that in this embodiment, the color filter layer 26 is formed on the transparent substrate 2.
2 and segment electric f! Although the segment electrodes 27 are formed between the segment electrodes 27, they may be formed on the transparent substrate 22 on which the segment electrodes 27 are formed.

Effects of the Invention As described above, according to the present invention, two types of display images can be displayed, the display diversity and versatility of the color liquid crystal display device are improved, and the range of use of the color liquid crystal display device is expanded. Expanded.

[Brief explanation of the drawing]

FIG. 1 shows a color liquid crystal display device 2 which is an embodiment of the present invention.
1 is a sectional view showing the configuration of 1, and FIG. 2 is a color liquid crystal display device 2.
1 is a plan view, FIG. 3 is an enlarged plan view showing the structure of the color filter layer 2.6, FIG. 4 is a sectional view showing the structure of the color filter layer 26, and FIG. 5 is a structure 2 of the segment electrode 27. A plan view, FIG. 6 is a diagram for explaining the orientation direction of liquid crystal molecules in the liquid crystal layer and the polarization direction of the polarizing plates 35 and 36 in the color liquid crystal display device 21, and FIG. 7 is an electrical configuration of the color liquid crystal display device 21. 8 is a timing chart for explaining the driving state of the color liquid crystal display device 21, FIG. 9 is a diagram showing a display example of the color liquid crystal display device 21, and FIG. 10 is a diagram showing the color liquid crystal display device 21. FIG. 11 is a cross-sectional view showing the configuration of a conventional color liquid crystal display device 1. FIG. 21... Color liquid crystal display device, 22. 25. 32 Transparent substrate, 23... First color display element section, 24... Second color display element section, 26... Color filter layer, 27.
33...Segment electrode, 29.35...Common electrode, 30.36...Liquid crystal layer, R...Red filter,
G... Green filter, B... Blue filter, Sr.
...Electrode for red color, Sg...Electrode for green color, sb...Electrode for blue color Patent attorney Keiichi Saikyo Figure 4 Figure 4

Claims (1)

[Scope of Claims] A first light-transmitting substrate; provided over the entire surface of one surface of the first light-transmitting substrate, each of which is provided in one of a plurality of predetermined colors for transmitting light; a plurality of color selection members to select; a second transparent substrate disposed on one surface side of the first transparent substrate; and a first liquid crystal layer interposed between the first and second transparent substrates. and a first transparent member provided within a predetermined display area on the first liquid crystal layer side and formed in a range corresponding to the plurality of color selection members selected in accordance with a predetermined color to be displayed in the display area. an electrode; a third transparent substrate disposed on the other surface side of the first transparent substrate; a second liquid crystal layer interposed between the first and third transparent substrates; and a second liquid crystal layer. a second transparent electrode provided in a predetermined display area on the side and formed in a range corresponding to the plurality of color selection members selected in accordance with a predetermined color to be displayed in the display area. Features a color liquid crystal display device.