JP2001166322A - Liquid crystal device and electronic equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display device excellent in display quality and an electronic equipment provided therewith, by preventing display quality from deteriorating, in the peripheral part of the display area of the liquid crystal display device using a chiral nematic liquid crystal having a bi-stable state through Frederick's transition. SOLUTION: Substrates 11, 12 are stuck with a prescribed gap via a sealing material 14, and a chiral nematic liquid crystal layer 13 is enclosed between the substrates. A color filter layer 17 is arranged on the inner surface of the substrate 12; striped transparent electrodes 11a, 12a are formed on the inner surfaces of the substrate 11 and the counter substrate 12 within the range of a display area 18; and dummy electrodes 11A, 12A are formed in the outside of the endmost arts of the transparent electrodes 11a, 12a. The color filter layer 17 is constituted of color pixels 17a and a black matrix 17b, and the black matrix 17b is formed on the color filter layer 17 within the range of dummy electrode areas 19, to form a shading film 17B.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bistable liquid crystal device using a chiral nematic liquid crystal and an electronic apparatus having the same, and more particularly, to a liquid crystal device capable of switching using the bistability and capable of simple matrix driving. The present invention relates to an apparatus and an electronic device including the same.

[0002]

2. Description of the Related Art In recent years, Japanese Patent Application Laid-Open Nos. 6-235920 and 6-230751 disclose a liquid crystal display device having a bistability using a chiral nematic liquid crystal. In this liquid crystal display device, the liquid crystal twisted at the twist angle φ in the initial state relaxes to two metastable states different from the initial state after applying a voltage exceeding the Freedericks transition, and the two metastable states It is characterized by performing bistable switching between them.

FIG. 5 is a schematic sectional view showing the structure of a simple matrix type liquid crystal display device 100 as an example of this liquid crystal display device.

As shown in FIG. 5, in a liquid crystal display device 100, a substrate 101 and an opposing substrate 102 are adhered at a predetermined interval on a peripheral portion of each substrate via a sealant 104, and the substrate 101 and the opposing substrate 102 The chiral nematic liquid crystal layer 103 is sealed between them.

On the inner surfaces of the substrate 101 and the counter substrate 102, transparent electrodes 101a and 102a are formed in stripes, respectively. Alignment films 101b and 102b for aligning liquid crystal are formed on the inner surfaces of the substrates 101 and 102 on which the transparent electrodes 101a and 102a are formed. The polarizer 10 is provided on the front and back of the liquid crystal display device 100.
5, 106 are attached.

Although not shown in the drawing, the substrate 10
A spherical spacer formed of glass, plastic, ceramic, or the like for keeping the distance (cell thickness) between the substrate 101 and the opposing substrate 102 constant.
It is located between the two.

In the initial state, the orientation films 101b and 102b are set so that the twist angle of the liquid crystal becomes φ.
When the liquid crystal molecules are aligned at the pretilt angles θ11 and θ12,
An orientation process is performed so as to be in contact with 1b and 102b.

In the liquid crystal display device 100, in the initial state, the directors of the liquid crystal molecules in contact with the alignment films 101b and 102b and the angles θ11 and θ12 between the substrates 101 and 102 may have opposite signs. It is a feature. For example, when the twist angle φ of the liquid crystal is 180 ° in the initial state, as shown in FIG. 5, the angle between the director vector of the liquid crystal molecules in contact with the alignment films 101b and 102b and the substrates 101 and 102 θ1
1, θ12 are antiparallel to each other. At this time, the rubbing process is performed on the alignment films 101b and 102b in directions indicated by arrows R11 (rightward in the drawing) and directions R12 (leftward in the drawing).

The chiral nematic liquid crystal of the liquid crystal display device 100 has two metastable states different from the initial state as a relaxation state when a voltage sufficient to cause the Freedericksz transition is applied. The twist angle of the liquid crystal in the two metastable states is φ-18
It is characterized by 0 ° and φ + 180 °. For example,
When the twist angle φ of the liquid crystal in the initial state is 180 °,
The twist angle of the liquid crystal in the metastable state is 0 ° (uniform state) on one side and 360 ° on the other side. Which metastable state to transition to after the Freedericksz transition depends on the waveform and absolute value of the voltage applied thereafter, and the metastable state has the property of spontaneously relaxing to the initial state.

The liquid crystal display device 100 selectively switches (bistable switching) between the two metastable states generated depending on the applied voltage, and the two metastable states are controlled by the polarizing plates 105 and 106. The display is performed by utilizing the optical identification.

[0011]

In general, in an operation mode having bistability or a plurality of stable states, the orientation state used for display is often not sufficiently energetically stable, and the surface state and local shape of the substrate are not always stable. There is a problem that a plurality of alignment states coexist due to a local displacement and display quality deteriorates. In the above-described liquid crystal display device 100, the peripheral portion of the transparent electrode pattern, that is, the transparent electrode pattern at the peripheral portion of the display region is used. However, there is a problem that a specific liquid crystal behavior occurs due to the shape effect, and the display quality in this region is deteriorated.

FIG. 6 is a plan view of the liquid crystal display device 100 described above. The same components as those in FIG. 5 are denoted by the same reference numerals, and description thereof will be omitted. In FIG. 6, the substrate 10
Transparent electrodes 101a, 102a formed on 1, 102
The intersections of are pixels, and display is possible. That is, the transparent electrode pattern is formed inside the sealant 104, and the display area 107 is formed.

Assuming that the transparent electrodes 101a1 and 102a1 disposed at the end of the display area 107 in FIG. 6 are transparent electrodes 101a1 and 102a1 inside the display area 107.
In the vicinity of a1, that is, one or two sides of the periphery of the transparent electrode pattern are adjacent to the sealing material 104, and a pattern different from the vicinity of the center of the display area 107 where the transparent electrodes are adjacent on all sides is formed. The above-described problem caused by the effect occurs, and the display quality deteriorates. The present inventors have found that this problem occurs in a region of one or more transparent electrodes within a range of about 300 μm from the outer peripheral portion of the display region 107. In addition, the above problem is particularly remarkable when a driving voltage waveform is applied and φ + 180 ° is selected as a twist angle of the liquid crystal in a metastable state.
Twist angle φ of the liquid crystal at the periphery of the transparent electrode pattern
The present inventors have found that -180 ° appears in the form of a domain, lowering the voltage margin and deteriorating the display quality.
Further, this phenomenon is caused by the intersection of the transparent electrodes 101a and 102a, that is, any one side of the pixel and
The present inventor has also found that this is most remarkable when the directions of the rubbing processes performed on b and 102b match.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a liquid crystal display device which solves the above-mentioned problems, prevents display quality from being deteriorated at a peripheral portion of a display area, and has excellent display quality, and an electronic apparatus having the same. I do.

[0015]

In order to solve the above-mentioned problems, the present invention has been made by using a chiral nematic between a pair of substrates having a transparent electrode and an alignment film for aligning a liquid crystal formed on an inner surface thereof. In the initial state, the liquid crystal is sandwiched, and the chiral nematic liquid crystal has a twisted structure with a twist angle φ, and two different states from the initial state as a relaxed state after applying a voltage that causes a Freedericks transition in the initial state. In a liquid crystal device having a metastable state, at least one dummy electrode is formed on the substrate, outside the transparent electrode disposed at the end of the display area.

It is preferable that a light-shielding film covering the dummy electrode is formed between the dummy electrode and the outermost surface of the liquid crystal device.

In the liquid crystal device, an angle between a director vector of liquid crystal molecules in contact with the alignment film and the substrate surface has an opposite sign in an initial state.

The twist angle of the liquid crystal in the two metastable states is φ-180 ° on one side and φ + 18 on the other side.
0 °. According to the above-described means, by forming at least one dummy electrode outside the transparent electrode disposed at the end of the display area, the transparent electrodes are adjacent on all sides even at the peripheral part in the display area, Since the pattern becomes the same as that of the central part of the region, it is possible to prevent the specific liquid crystal behavior caused by the shape effect of the transparent electrode pattern in the display region, so that it is possible to provide a liquid crystal display device having excellent display quality. it can. Further, by forming a light-shielding film covering the dummy electrode between the dummy electrode and the outermost surface of the liquid crystal display device, the display by the dummy electrode is not recognized from the outside, so that the display is not adversely affected.

Further, by providing this liquid crystal display device on the front side of the display surface, it is possible to provide an electronic device having excellent display quality. In the electronic device including the liquid crystal display device, the light-shielding film covering the dummy electrode does not need to be formed inside the liquid crystal device, and may be formed between the dummy electrode and the outermost surface of the electronic device so as to cover the dummy electrode.

[0020]

Next, an embodiment according to the present invention will be described in detail.

First Embodiment FIGS. 1 and 2 show a simple matrix type liquid crystal display device 1 for color display according to a first embodiment of the present invention.
0 shows a schematic sectional view and a schematic plan view. 1 and 2, the same components are denoted by the same reference numerals.

As shown in FIG. 1, in a liquid crystal display device 10, a substrate (lower substrate) 11 and a counter substrate (upper substrate) 12 are provided at predetermined positions on the peripheral edge of each substrate via a sealing material 14. A liquid crystal layer 13 composed of a chiral nematic liquid crystal and adhered at an interval between the substrate 11 and the opposing substrate 12.
Is enclosed. Also, in FIG.
Is provided with a color filter layer 17 on the inner surface thereof. As shown in FIG. 1 and FIG.
A plurality of stripe-shaped transparent electrodes 11a on the inner surface of
12a and dummy electrodes 11A and 12A are formed.
Assuming that the display area is 18, the transparent electrodes 11a and 12a are formed within the range of the display area 18, and at least one dummy electrode 11A and 12A is provided outside the transparent electrodes 11a and 12a arranged at the end in the display area 18. Are formed. In the drawing, as an example, dummy electrodes 11A, 12A
Are formed two by two. The dummy electrodes 11A and 12A are electrodes irrelevant to the display, and may or may not flow a current. The dummy electrodes 11A, 12A
The number A corresponds to the number of transparent electrodes belonging to a range in which display quality deteriorates in the related art. Dummy electrodes 11A, 1
The region where 2A is formed is referred to as a dummy electrode region 19. The color filter layer 17 includes R, G, and B color pixels 17a for displaying red, green, and blue, respectively, and a light shielding layer 17b formed of a black matrix that does not transmit light formed between the color pixels. I have. In the present embodiment, in order to prevent the display by the dummy electrodes 11A and 12A from being recognized from the outside, as shown in FIG. Then, the light shielding film 17B is formed.

Further, as shown in FIG.
Alignment films 11b and 12b for aligning liquid crystals are formed on the inner surfaces of the substrates 11 and 12 on which the dummy electrodes 11A and 12A are formed. Polarizing plates 15 and 16 are attached to the front and back of the liquid crystal display device 10.

Although not shown, a spherical spacer made of glass, plastic, ceramic, or the like for keeping the distance (cell thickness) between the substrate 11 and the counter substrate 12 constant is provided on the substrate 11, It is arranged between the opposing substrates 12.

In the initial state, the alignment films 11b and 12b are set so that the liquid crystal has a twist angle φ, and the liquid crystal molecules have a pretilt angle θ1 and θ2.
Is oriented so as to be in contact with.

In the present embodiment, in the initial state, the angle θ 1 between the director vectors of the liquid crystal molecules in contact with the alignment films 11 b and 12 b and the substrates 11 and 12,
θ2 have opposite signs. For example, when the twist angle φ of the liquid crystal is 180 ° in the initial state, the angle formed between the director vectors of the liquid crystal molecules in contact with the alignment films 11b and 12b and the substrates 11 and 12, as shown in FIG. θ1 and θ2 are antiparallel to each other. At this time, the rubbing process is performed on the alignment films 11b and 12b in the directions of arrows R1 (rightward in the figure) and R2 (leftward in the figure), respectively.

The chiral nematic liquid crystal of the liquid crystal display device 10 has two metastable states different from the initial state as a relaxed state when a voltage sufficient to cause the Freedericksz transition is applied. The twist angle of the liquid crystal in the two metastable states is φ−180, respectively.
゜, φ + 180 °. For example, when the twist angle φ of the liquid crystal in the initial state is 180 °, one of the twist angles of the liquid crystal in the metastable state is 0 ° (uniform state).
And the other becomes 360 °. Which metastable state to transition to after the Freedericksz transition depends on the waveform and absolute value of the voltage applied thereafter, and the metastable state has the property of spontaneously relaxing to the initial state.

The liquid crystal display device 10 selectively switches (bistable switching) between the two metastable states that occur depending on the applied voltage, and the two metastable states are controlled by the polarizing plates 15 and 16. The display is performed using the optical identification.

The area of the liquid crystal display device 10 of the present embodiment is:
Although the drawing is larger than the conventional liquid crystal display device 100 shown in FIG. 6, the transparent electrodes 11a and 12a
And the thickness of one of the dummy electrodes 11A and 12A is several tens of μm.
m, and the dummy electrode region 19 is about 300 μm from the inside of the sealing material 14, and thus has an area equivalent to that of the conventional liquid crystal display device 100.

According to the present embodiment, the transparent electrodes 11a, 12 disposed at the outermost ends in the range of the display area 18.
a at least one dummy electrode 11A, 12A
Is formed, the transparent electrodes are adjacent to the periphery of the display area 18 on all sides and have a pattern similar to that of the central part of the display area 18. Liquid crystal behavior does not occur,
A liquid crystal display device having excellent display quality can be provided.

In this embodiment, since the light-shielding film 17B is formed in the area of the dummy electrode region 19, the display by the dummy electrodes 11A and 12A is not recognized from the outside. Will not give.

Further, by providing this liquid crystal display device on the front side of the display surface, it is possible to provide an electronic device having excellent display quality.

In this embodiment, the light-shielding film 17B is formed on the color filter layer 17. However, the present invention is not limited to this. The light-shielding film 17B may be formed so that the display by the dummy electrodes 11A and 12A is not recognized from the outside. In the liquid crystal display device 10 or an electronic device including the same, the dummy electrode 11 is provided at any position between the dummy electrode 12A and the outermost surface of the liquid crystal display device 10 or the outermost surface of the electronic device.
The light-shielding film 17B may be formed so as to cover A and 12A. Further, the liquid crystal display device 1 can be provided without providing the light shielding film 17B.
0, the dummy electrodes 11A, 12A
If a cover or the like is disposed so as to cover
B can be substituted, and the same effect can be obtained.

Second Embodiment FIG. 3 is a schematic sectional view of a simple matrix type liquid crystal display device 20 for monochrome display according to a second embodiment of the present invention.

In the liquid crystal display device 20, the same components as those of the liquid crystal display device 10 are denoted by the same reference numerals, and description thereof will be omitted.

As shown in FIG. 3, in the liquid crystal display device 20, as in the liquid crystal display device 10, the substrate 11 and the opposing substrate 12 are provided with a sealing material 14 at the periphery of each substrate.
Are attached at predetermined intervals through the substrate 11, the counter substrate 12
The chiral nematic liquid crystal layer 13 is enclosed between them. In the liquid crystal display device 20, the liquid crystal display device 1
0, the transparent electrodes 11a and 12a and the dummy electrode 11
A and 12A are formed.

In this embodiment, the dummy electrodes 11A,
In order to prevent the display by 12A from being recognized from the outside, a light shielding film 21 is formed on the outer surface of the polarizing plate 16 within the range of the dummy electrode region 19.

According to the present embodiment, at least one dummy electrode 11A, 12A is formed outside the outermost transparent electrodes 11a, 12a within the display area 18 as in the first embodiment. The display area 1
Since the transparent electrodes are adjacent to each other also in the peripheral portion of 8 and have the same pattern as the central portion of the display region 18, the specific liquid crystal behavior due to the shape effect does not occur within the display region 18. Thus, a liquid crystal display device having excellent display quality can be provided.

In this embodiment, since the light-shielding film 21 is formed within the area of the dummy electrode region 19 on the outer surface of the polarizing plate 16, the display by the dummy electrodes 11A and 12A is not recognized from the outside. Electrode 11A,
Forming 12A does not adversely affect the display.

Further, by providing this liquid crystal display device on the front side of the display surface, it is possible to provide an electronic device having excellent display quality.

In this embodiment, the light-shielding film 21 is formed on the outer surface of the polarizing plate 16. However, the present invention is not limited to this. If the light-shielding film 21 is formed so that the display by the dummy electrodes 11A and 12A is not recognized from the outside. Because it is good, the liquid crystal display device 2
0 or inside the electronic device having the same, the dummy electrodes 11A and 12A are located at any position between the dummy electrode 12A and the outermost surface of the liquid crystal display device 20 or the outermost surface of the electronic device.
A may be formed so as to cover A. Further, in an electronic device including the liquid crystal display device 20 without the light-shielding film 21, if a cover or the like is arranged so as to cover the dummy electrodes 11A and 12A, it can be used as a substitute for the light-shielding film. Can be obtained.

Next, a specific example of an electronic apparatus provided with any one of the liquid crystal display devices 10 and 20 of the first and second embodiments will be described.

FIG. 4A is a perspective view showing an example of a mobile phone. In FIG. 4A, reference numeral 200 denotes a mobile phone main body, and reference numeral 201 denotes a liquid crystal display unit including the liquid crystal display device 10 or 20 described above.

FIG. 4B is a perspective view showing an example of a portable information processing device such as a word processor or a personal computer. Fig. 4 (b)
In the figure, reference numeral 300 denotes an information processing apparatus, 301 denotes an input unit such as a keyboard, 303 denotes an information processing main body, and 302 denotes a liquid crystal display unit including the liquid crystal display device 10 or 20 described above.

FIG. 4C is a perspective view showing an example of a wristwatch-type electronic device. In FIG. 4C, reference numeral 400 denotes a watch main body, and reference numeral 401 denotes a liquid crystal display unit including the liquid crystal display device 10 or 20 described above.

Each of the electronic devices shown in FIGS. 4A to 4C has the above-described liquid crystal display device 10 or 20, and thus has excellent display quality.

[0047]

As described above, according to the present invention, by forming at least one dummy electrode outside the transparent electrode disposed at the end in the display area, the peripheral area of the display area can be formed. Since the transparent electrodes are adjacent on all sides and have the same pattern as the central part of the display area, it is possible to prevent the specific liquid crystal behavior caused by the shape effect in the display area, so that the liquid crystal display device having excellent display quality Can be provided. In addition, by providing the liquid crystal display device on the front side of the display surface, an electronic device with excellent display quality can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing the structure of a liquid crystal display device according to an embodiment of the present invention.

FIG. 2 is a schematic plan view illustrating a structure of a liquid crystal display device according to an embodiment of the present invention.

FIG. 3 is a schematic cross-sectional view illustrating a structure of a liquid crystal display device according to an embodiment of the present invention.

FIG. 4A is a diagram illustrating an example of a mobile phone including the above embodiment, FIG. 4B is a diagram illustrating an example of a portable information processing device including the above embodiment, and FIG. c) is a diagram showing an example of a wristwatch-type electronic device having the above embodiment.

FIG. 5 is a schematic sectional view showing the structure of a conventional liquid crystal display device.

FIG. 6 is a schematic plan view showing the structure of a conventional liquid crystal display device.

[Explanation of symbols]

Reference Signs List 10, 20 Liquid crystal display device 11 Substrate 12 Counter substrate 11a, 12a Transparent electrode 11A, 12A Dummy electrode 11b, 12b Alignment film 13 Liquid crystal layer 14 Sealing material 15, 16 Polarizer 17 Color filter layer 17a Color pixel 17b Light shielding layer (black matrix) 17B Light-shielding film (black matrix) 18 Display area 19 Dummy electrode area 21 Light-shielding film R1, R2 Rubbing direction θ1, θ2 Angle between liquid crystal director vector in contact with alignment film and substrate

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H088 EA03 GA02 HA02 HA04 JA28 LA06 MA04 2H092 GA05 GA61 JB52 NA04 NA29 NA30 PA03 QA18 5C006 AF59 BA11 BB12 FA22 5C080 AA10 BB05 DD05 DD09 JJ06 5C094 AA02 BA43 CA19 EC03 EA04 EB04 ED02 ED14 ED15 ED20 HA10

Claims (5)

[Claims] 1. A chiral nematic liquid crystal is sandwiched between a pair of substrates having an inner surface on which a transparent electrode and an alignment film for aligning liquid crystal are formed, and the chiral nematic liquid crystal has a twist angle of twist φ in an initial state. In a liquid crystal device having a structure and two metastable states different from the initial state as a relaxed state after applying a voltage that causes a Freedericks transition in the initial state, the liquid crystal device has an edge of a display region on the substrate. Wherein at least one dummy electrode is formed outside the transparent electrode arranged in the portion. 2. The liquid crystal device according to claim 1, wherein a light-shielding film covering the dummy electrode is formed between the dummy electrode and an outermost surface of the liquid crystal device. 3. The liquid crystal device according to claim 1, wherein an angle between a director vector of liquid crystal molecules in contact with the alignment film and the substrate surface has an opposite sign in an initial state. A liquid crystal device characterized by the above-mentioned. 4. One of claims 1 to 3
3. The liquid crystal device according to claim 1, wherein one of the twist angles of the liquid crystal in the two metastable states is φ-180 ° and the other is φ + 180 °. 5. An electronic device comprising the liquid crystal device according to claim 1, on a front surface side of a display surface, wherein the dummy electrode and an outermost surface of the electronic device are provided. An electronic device, wherein a light shielding film covering the dummy electrode is formed therebetween.