JP2002207225A - Liquid crystal display element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display element in which a liquid crystal layer containing a liquid crystal composition showing a cholesteric phase at room temperature is held between a pair of substrates and to provide a liquid crystal display element which is produced by stacking a plurality of liquid crystal display elements, which can be driven at a low-voltage, which is bright with good contrast and a wide temperature range for the capability of practical use. SOLUTION: In the liquid crystal display elements R, G, B having liquid crystal layers 10r, 10g, 10b containing liquid crystal compositions 6r, 6g, 6b, respectively and showing a cholesteric phase at room temperature each held between a pair of electrode substrates 11, 12, the liquid crystal composition is a chiral nematic liquid crystal composition containing a mixture of a chiral material and a nematic liquid crystal and contains the chiral material by 7 to 40 wt.% of the whole liquid crystal composition. The nematic liquid crystal component shows 0.13 to 0.23 refractive index anisotropy and 0.50 to 1.10 V electro-optical threshold voltage (V10%) and 1.15 to 1.80 V electro-optical saturation voltage (V90%) measured by the measurement method specified by JIS C7072.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a liquid crystal display device.

[0002]

2. Description of the Related Art A liquid crystal display element basically comprises a pair of substrates having transparent electrodes and a liquid crystal layer sandwiched between the substrates. By applying a predetermined drive voltage to the liquid crystal layer, the arrangement of liquid crystal molecules in the liquid crystal layer is controlled, and external light incident on the liquid crystal display element is modulated to display a target image. Further, in a liquid crystal display device, a space holding material may be disposed between the pair of substrates in order to maintain a space between the pair of substrates.

Various types of liquid crystal display devices have been proposed. In recent years, a liquid crystal display using a chiral nematic liquid crystal that exhibits a cholesteric phase at room temperature by adding a chiral material to the nematic liquid crystal has been proposed. Various devices have been studied.

[0004] Such a liquid crystal display device is sometimes used as a reflection type liquid crystal display device characterized by low power consumption utilizing selective reflection of chiral nematic liquid crystal. In this reflective liquid crystal display element, display is performed by switching the liquid crystal between a planar state (a colored state by selectively reflecting visible light of a specific wavelength) and a focal conic state (a transparent state) by applying a high or low pulse voltage. These states are maintained even after the application of the pulse voltage is stopped. Such retention of planar and focal conic states is generally referred to as bistability or memory.

As one method for realizing full-color display using the liquid crystal display element, a laminated liquid crystal layer including an R liquid crystal layer for displaying red, a G liquid crystal layer for displaying green, and a B liquid crystal layer for displaying blue is used. A case where a liquid crystal display element is employed can be given.

In a conventional reflection type liquid crystal display device using a chiral nematic liquid crystal, it is necessary to apply a driving voltage of at least about 60 V in order to drive it, and a lower voltage driving is possible. A liquid crystal display device is desired. In particular, in order to use a general-purpose inexpensive driving IC as a driving IC for driving the liquid crystal display element, it is necessary to provide a liquid crystal display element that can be driven at about 40 V or less.

To drive a liquid crystal display device at a low voltage,
For example, the thickness of the liquid crystal layer may be reduced.

[0008]

However, in a reflection type liquid crystal display device using a chiral nematic liquid crystal, when the thickness of the liquid crystal layer is reduced in order to drive at a low voltage, the light reflectance in image display is satisfactory. It was not as high as possible, and it was difficult to obtain sufficient contrast between the planar state and the focal conic state.

Further, in this type of liquid crystal display device, it has been required that the usable temperature range be extended to such an extent that it can be actually used.

Accordingly, the present invention provides a liquid crystal display device in which a liquid crystal layer containing a liquid crystal composition exhibiting a cholesteric phase at room temperature is sandwiched between a pair of substrates, which can be driven at a low voltage and has a large light reflectance. It is an object of the present invention to provide a liquid crystal display device having a high contrast, a high contrast, and a wide practicable temperature range.

The present invention also provides a multi-layer liquid crystal display device which is low in voltage drive, is bright, has good contrast, and has a wide practical temperature range, in which a plurality of liquid crystal display devices including at least one such liquid crystal display device are laminated. The task is to provide

[0012]

Means for Solving the Problems The inventor of the present invention has conducted intensive studies to solve the above-mentioned problems, and found the following.

That is, in a liquid crystal display device in which a liquid crystal layer containing a liquid crystal composition exhibiting a cholesteric phase at room temperature (or ordinary temperature) is sandwiched between a pair of substrates with electrodes, a mixture of a chiral material and a nematic liquid crystal is used as the liquid crystal composition. And the chiral material is contained in an amount of 7% by weight to 4% by weight based on the entire liquid crystal composition.
Using a chiral nematic liquid crystal composition containing 0% by weight, with respect to the nematic liquid crystal component, the refractive index anisotropy was set to 0.13 to 0.23, and electro-optical measurement was performed by a measurement method specified in JIS C7072. Threshold voltage (V
10%) is set to 0.50 V to 1.10 V, and JIS C7
When the electro-optical saturation voltage (V90%) measured by the measurement method specified in 072 is 1.15 V to 1.80 V,
Good properties such as good color purity and light reflectance are obtained, and the contrast is improved. In addition, the usable temperature range is wide and the driving voltage is low.

The present invention is based on this finding,
In order to solve the above problem, a liquid crystal display in which a liquid crystal layer containing a liquid crystal composition exhibiting a cholesteric phase at room temperature (or room temperature) is sandwiched between a pair of substrates with electrodes (usually at least one pair of substrates with electrodes). In the device, the liquid crystal composition includes a mixture of a chiral material and a nematic liquid crystal, and the chiral material is contained in an amount of 7% to 40% by weight based on the entire liquid crystal composition.
A chiral nematic liquid crystal composition containing
The nematic liquid crystal component has a refractive index anisotropy of 0.13 to 0.13.
0.23, the electro-optical threshold voltage (V10%) measured by the measurement method specified in JIS C7072 is 0.50
V to 1.10 V, the electro-optical saturation voltage (V90%) measured by the measurement method specified in JIS C7072 is 1.1.
Provided is a liquid crystal display device having a voltage of 5 V to 1.80 V.

The liquid crystal display device according to the present invention can be used as a reflection type liquid crystal display device utilizing selective reflection of a liquid crystal exhibiting a cholesteric phase at room temperature (or ordinary temperature).

When the liquid crystal display element of the present invention is used as a reflection type liquid crystal display element, display is performed by switching the liquid crystal between a planar state (colored state) and a focal conic state (transparent state) by applying a high or low voltage.

According to the liquid crystal display device of the present invention, the liquid crystal composition contains a mixture of a chiral material and a nematic liquid crystal, and the chiral material is contained in an amount of 7% by weight to the entire liquid crystal composition.
It is a chiral nematic liquid crystal composition containing 40% by weight. The nematic liquid crystal component has a refractive index anisotropy of 0.13 to 0.23 and an electro-optical threshold voltage (V10%) measured by a measurement method specified in JIS C7072.
Is 0.50 V to 1.10 V, and an electro-optical saturation voltage (V90) measured by a measurement method specified in JIS C7072.
%) Is 1.15 V to 1.80 V, it is possible to drive at a low voltage, obtain a large light reflectance, and obtain a high contrast. Further, the practicable temperature range is wide.

In the liquid crystal display device according to the present invention, the chiral nematic liquid crystal composition has a specific resistance of a nematic liquid crystal component contained therein of 5 × 10 ¹⁰ (Ω · c).
m) to about 5 × 10 ¹² (Ω · cm), the driving voltage applied to the liquid crystal display element is reduced. If the specific resistance is too high, the driving voltage tends to increase. On the other hand, if it is too low, the stability of repeated display is likely to be reduced, or crosstalk, image defects, and image noise are likely to occur.

The refractive index anisotropy of the nematic liquid crystal component is from 0.13 to 0.23. If the refractive index anisotropy is too low, the color purity of reflected light tends to deteriorate, and the light reflectance tends to decrease. Conversely, if it is too high, the viewing angle dependency tends to increase.

The electro-optical threshold voltage (V 10%) and the electro-optical saturation voltage (V 9
0%) are 0.50 V to 1.10 V and 1.15 respectively.
However, if at least one of them is too high, the driving voltage applied to the liquid crystal display element tends to be high. Conversely, if at least one of them is too low, crosstalk, image defects, and image noise will occur. Is more likely to occur.

Although the liquid crystal display device according to the present invention can be driven at a low voltage, its voltage value can be, for example, about 40 V or less. In this case, a general-purpose and inexpensive driving IC can be used as the driving IC for driving the liquid crystal display element.

In the liquid crystal display device according to the present invention, a space holding material may be provided between the pair of substrates in order to maintain a space between the substrates. Examples of the space holding material include a spacer and a columnar structure. The spacer and the columnar structure will be described in detail in an embodiment of the invention described later.

Examples of the chiral material added to the chiral nematic liquid crystal composition include those represented by the following chemical structural formulas (E ₁ ).
This is shown in (E ₆ ). However, it is not limited to this.

[0024]

Embedded image

In any case, the chiral nematic liquid crystal composition exhibits a cholesteric phase having a selective reflection wavelength in a visible wavelength range at room temperature (or ordinary temperature). For example, as a chiral nematic liquid crystal composition, (a) a chiral nematic liquid crystal composition exhibiting a cholesteric phase having a selective reflection wavelength in a red wavelength region at room temperature (or ordinary temperature);
A chiral nematic liquid crystal composition exhibiting a cholesteric phase having a selective reflection wavelength in a green wavelength region at room temperature (or ordinary temperature), and (c) a chiral nematic liquid crystal exhibiting a cholesteric phase having a selective reflection wavelength in a blue wavelength region at room temperature (or ordinary temperature). Compositions may be mentioned.

In the chiral nematic liquid crystal composition having the selective reflection wavelength in the red wavelength region (a), the content of the chiral material to the whole liquid crystal composition can be, for example, about 7% by weight to 25% by weight. . The refractive index anisotropy of the nematic liquid crystal component contained in the chiral nematic liquid crystal composition is not limited to this, but is preferably about 0.16 to 0.20.

In the chiral nematic liquid crystal composition (b) in which the selective reflection wavelength is in the green wavelength region, the content of the chiral material with respect to the entire liquid crystal composition can be, for example, about 10% by weight to 30% by weight. . In addition, the refractive index anisotropy of the nematic liquid crystal component contained in the chiral nematic liquid crystal composition is not limited thereto, but is preferably about 0.13 to 0.18.

In the chiral nematic liquid crystal composition having the selective reflection wavelength in the blue wavelength region (c), the content of the chiral material with respect to the entire liquid crystal composition can be, for example, about 15% by weight to 40% by weight. . The refractive index anisotropy of the nematic liquid crystal component contained in the chiral nematic liquid crystal composition is not limited to this, but is preferably about 0.13 to 0.20.

The present invention also relates to a multi-layer liquid crystal display device comprising a plurality of liquid crystal layers each sandwiched between a pair of substrates, wherein at least one of the plurality of liquid crystal layers has the liquid crystal layer. In addition to a pair of substrates sandwiching a liquid crystal layer, the present invention also provides a multilayer liquid crystal display device constituting the above liquid crystal display device.

In the multi-layer liquid crystal display device, two or more colors can be displayed by using a plurality of liquid crystal display devices that display different colors. Note that full-color display can be performed by employing at least three liquid crystal display elements, a liquid crystal display element that performs blue display, a liquid crystal display element that performs green display, and a liquid crystal display element that performs red display.

In any case, as the multi-layer liquid crystal display device, at least one of the liquid crystal display devices according to the present invention is used.
One example is a multi-layer liquid crystal display element in which a plurality of liquid crystal display elements are included (all may be the same). In this case, adjacent liquid crystal display elements may have a common substrate between them.

When a full-color display is performed using the liquid crystal display device of the present invention, three liquid crystal display devices each containing the above chiral nematic liquid crystal compositions (a) to (c), for example, when the selective reflection wavelength is room temperature A liquid crystal display element containing a chiral nematic liquid crystal composition containing a chiral material in an amount of 7% to 25% by weight in a red wavelength region at (or room temperature), and a green wavelength region at a selective reflection wavelength of room temperature (or room temperature). A liquid crystal display device comprising a chiral nematic liquid crystal composition containing 10% to 30% by weight of a chiral material, a selective reflection wavelength in a blue wavelength range at room temperature (or room temperature), and a chiral material of 15% by weight. % Of the liquid crystal display element containing a chiral nematic liquid crystal composition containing from 40% to 40% by weight, a low-voltage driving is possible and a good liquid crystal display element is obtained. It is possible to achieve a color display quality.

In any case, a dye may be added to the liquid crystal composition to absorb an extra scattering component on the shorter wavelength side than the selective reflection wavelength to improve the contrast in image display. In this case, as the dye to be added, conventionally known various dyes can be used, and a dye having good compatibility with the liquid crystal is suitably used. For example, an azo compound, a quinone compound, an anthraquinone compound, or a dichroic dye can be used, and a plurality of these dyes may be used. The addition amount is desirably, for example, about 3% by weight or less based on the total amount of the nematic liquid crystal and the chiral material. If the addition amount is too large, the selective reflection amount of the liquid crystal tends to decrease, and conversely, the contrast may decrease.

In addition, a color filter can be employed instead of adding a dye to the liquid crystal composition. In this case, for example, a liquid crystal display element can be provided with a filter layer. As a material that can be used for the filter layer, for example, a colorless transparent substance to which a dye is added, or a material that is essentially colored without adding a dye may be used. For example, the filter layer may be a thin film made of a specific substance having the same function as a dye. The same effect can be obtained by replacing the transparent substrate itself for forming the liquid crystal display element with the above filter layer material.

In any case, at least one of the pair of substrates may be a substrate made of a resin material.

[0036]

Embodiments of the present invention will be described below with reference to the drawings.

The liquid crystal display device according to the present invention can be formed, for example, in the following structure.

FIG. 1 is a schematic sectional view of an example of the liquid crystal display device according to the present invention. FIG. 2 shows an example of a multi-layer liquid crystal display element according to the present invention. The liquid crystal display element performs blue display, the liquid crystal display element performs green display, and the liquid crystal display element performs red display. It is a schematic sectional drawing of the laminated liquid crystal display element laminated in this order. In addition, in the liquid crystal display device of FIGS. 1 and 2, portions having basically the same configuration and operation are denoted by the same reference numerals.

In the liquid crystal display device shown in FIG. 1, a liquid crystal layer 10 containing a liquid crystal composition 6 exhibiting a cholesteric phase at room temperature is sandwiched between a pair of substrates 1 and 2 with electrodes. Both substrates 1, 2
A resin structure 4 and a spacer 5 serving as a space holding material for holding the space between the two substrates are arranged between them.

Each of the liquid crystal display elements B, G, and R in the multi-layer liquid crystal display element shown in FIG.
Liquid crystal layers 10b, 10g, and 10r for performing blue display, green display, and red display including b, 6g, and 6r are sandwiched, respectively. A resin structure 4 and a spacer 5 are disposed between the substrates 1 and 2 sandwiching the liquid crystal layers 10b, 10g, and 10r, respectively, as a space holding material for maintaining an interval between the substrates.

In the liquid crystal display device shown in FIGS. 1 and 2,
The substrates 1 and 2 are a pair of substrates at least one of which has a light transmitting property. Here, each of the substrates 1 and 2 is a transparent substrate having a light-transmitting property. On each surface of the transparent substrates 1 and 2, there are provided a plurality of strip-shaped transparent electrodes 11 and 12 which are parallel to each other. I have. These electrodes 11, 12
Are facing each other so as to cross each other. It is preferable that an insulating thin film is coated on the electrode. Here, an insulating film 7 is coated on the electrodes 11 and 12, respectively, and an alignment stabilizing film 8 is formed on the insulating film 7.
Are provided respectively.

A visible light absorbing layer is provided on the outer surface (back surface) of the substrate on the side opposite to the side where light is incident, if necessary. In the example of FIG. 1, the outer surface (back surface) of the substrate 2 is
In the example, the outer surface (back surface) of the substrate 2 in the liquid crystal display element R
Is provided with a visible light absorbing layer 3.

S is a sealing material, and the liquid crystal compositions 6 and 6
b, 6g, and 6r are provided between the substrates 1 and 2.

Reference numeral 25 denotes a pulse power source,
A predetermined pulse-like voltage is applied to 12. (Substrate) The substrates 1 and 2 have a light-transmitting property as described above, but a glass substrate can be exemplified as the light-transmitting substrate. In addition to this glass substrate, for example, polycarbonate (PC), polyether sulfone (PE)
A flexible substrate such as S), polyarylate (PAr), or polyethylene terephthalate (PET) can be used. (Electrode) As an electrode, for example, Indium Tin
Oxide (ITO: indium tin oxide), Ind
transparent conductive film such as ium zinc oxide (IZO: indium zinc oxide), metal electrode such as aluminum or silicon, or amorphous silicon or BSO
(Bismuth Silicon Oxide) or the like can be used.

In the liquid crystal display device shown in FIGS. 1 and 2, a plurality of strip-shaped transparent electrodes 11 and 12 parallel to each other are formed on the surfaces of the transparent substrates 1 and 2 as described above.
These electrodes 11 and 12 face each other so as to cross each other.

In order to form the electrodes in this manner, for example, an ITO film may be vapor-deposited on a transparent substrate by masking using a sputtering method or the like, or an ITO film may be entirely formed and then patterned by photolithography.

Including the liquid crystal display device shown in FIGS. 1 and 2,
In the liquid crystal display element of the present invention, an insulating thin film having a function of preventing a short circuit between electrodes or improving the reliability of the liquid crystal display element as a gas barrier layer may be formed. Also,
An alignment stabilizing film can be provided on the substrate as needed. As described above, the insulating films 7 are coated on the electrodes 11 and 12, respectively, and the alignment stabilizing films 8 are provided on the insulating films 7, respectively. (Insulating Thin Film) Examples of the insulating thin film include an inorganic film made of an inorganic material such as silicon oxide, titanium oxide, zirconium oxide and alkoxide thereof, and an organic film made of an organic material such as a polyimide resin, an acrylic resin, and a urethane resin. . The insulating thin film can be formed using these materials by a known method such as an evaporation method, a spin coating method, and a roll coating method. Further, if a dye is added to the above-mentioned material, it functions as a color filter. Further, the insulating thin film can be formed using the same material as the polymer resin used for the resin structure. (Orientation stabilizing film) As the orientation stabilizing film, polyimide resin, polyamideimide resin, polyetherimide resin,
Examples thereof include an organic film made of an organic material such as a polyvinyl butyral resin and an acrylic resin, and an inorganic film made of an inorganic material such as silicon oxide and aluminum oxide. It is not necessary to perform a rubbing treatment or the like on the alignment stabilizing film formed using these materials. Further, the orientation stabilizing film may be used also as the insulating thin film. (Spacer) Including the liquid crystal display device shown in FIG. 1 and FIG.
In the liquid crystal display element of the present invention, a spacer may be provided between the pair of substrates as a space holding member for uniformly holding a gap between the substrates. 1 and 2, the spacer 5 is arranged between the substrates 1 and 2 as described above.

As the spacer, a sphere made of resin or inorganic oxide can be exemplified. Further, a fixed spacer having a surface coated with a thermoplastic resin can also be suitably used. Note that both the spacer and the resin structure may be provided as in the liquid crystal display device of FIGS. 1 and 2, but only the spacer may be used as the space holding member instead of the resin structure. This state is shown in FIGS. 3 and 4, the illustration of the pulse power supply 25 is omitted. (Liquid crystal composition) Each of the liquid crystal compositions 6r, 6g, and 6b contained in the liquid crystal layers 10r, 10g, and 10b is a mixture of a chiral material and a nematic liquid crystal. It is a chiral nematic liquid crystal composition contained. The nematic liquid crystal component has a refractive index anisotropy of 0.13 to 0.23, J
The electro-optical threshold voltage (V10%) measured by the measurement method specified in IS C7072 is 0.50 V or more.
1.10 V, the electro-optical saturation voltage (V90%) measured by the measurement method specified in JIS C7072 is 1.15 V to 1.80 V in all cases.

More specifically, the liquid crystal composition 6r in the liquid crystal layer 10r (red layer) is a mixture of a chiral material and a nematic liquid crystal.
It is a chiral nematic liquid crystal composition containing 0.1% by weight.

The liquid crystal composition 6 g in the liquid crystal layer 10 g (green layer) is a chiral nematic liquid crystal composition in which a chiral material and a nematic liquid crystal are mixed and the chiral material is contained in an amount of 10 to 30% by weight. .

The liquid crystal composition 6b in the liquid crystal layer 10b (blue layer) is a chiral nematic liquid crystal composition containing a mixture of a chiral material and a nematic liquid crystal and containing 15 to 40% by weight of the chiral material. .

The content of the chiral material in each of the liquid crystal compositions 6r, 6g and 6b is a value when the total amount of the nematic liquid crystal component and the chiral material is 100% by weight.

The specific resistance of the nematic liquid crystal components contained in each of the chiral nematic liquid crystal compositions 6r, 6g, and 6b is 5 × 10 ¹⁰ (Ω · cm) to 5 × 10 ¹² here.
(Ω · cm). (Resin Structure) The liquid crystal display element of the present invention, including the liquid crystal display element shown in FIGS. 1 and 2, is supported by a structure as a space holding member between a pair of substrates in order to impart strong self-holding properties. It may be. 1 and 2, a resin structure 4 is provided between substrates 1 and 2. FIG. 6 shows an example of an arrangement state of the resin structure 4.

First, the structure of the resin structure will be described. Examples of the resin structure include, for example, a columnar body, a square columnar body, an elliptical columnar body, a trapezoidal columnar body, a conical columnar body, and the like, which are arranged at predetermined intervals in a predetermined pattern such as a lattice arrangement (see FIG. 6). Columnar structures can be mentioned.
Further, stripe-shaped ones arranged at predetermined intervals may be used. This columnar structure is not a random arrangement, but can maintain the gap between the substrates appropriately, such as an equidistant arrangement, an arrangement in which the interval is gradually changed, an arrangement in which a predetermined arrangement pattern is repeated at a constant cycle, and an image. It is preferable that the array is designed so as not to disturb the display. When the ratio of the area occupied by the columnar structure to the display region of the liquid crystal display element is 1% to 40%, practically satisfactory characteristics can be obtained as a liquid crystal display element while maintaining appropriate strength.

As the material of the columnar structure, various resin materials such as a thermoplastic resin material, a thermosetting resin material, and a photocurable resin material can be used.

The columnar structure can be formed by a method of directly arranging a resin material by screen printing or the like, or a method of forming the resin material by a photolithography process using a mask after applying the resin material.

In order to form a liquid crystal display element, a liquid crystal composition may be injected between substrates sandwiching the columnar structure by a vacuum injection method or the like. Alternatively, the liquid crystal composition may be dropped when the substrates are bonded, and the liquid crystal composition may be sealed at the same time as the substrates are bonded.

Further, in order to improve the accuracy of the gap control between the substrates, when forming the columnar structure, a spacer material having a size smaller than the height of the columnar structure, for example, glass fiber, ball-shaped glass or ceramic powder, or If spherical particles made of an organic material are arranged so that the gap does not change by heating or pressing, the gap accuracy can be further improved, and voltage unevenness and display unevenness can be reduced accordingly. (Seal material) As a material of the seal material, a material used for the above-mentioned resin structure, for example, a photocurable resin material, a thermoplastic resin material, a thermosetting resin material, or the like can be used. This sealing material is formed, for example, by discharging a resin from the tip of a nozzle onto the substrate, such as a dispenser method or an inkjet method, on a peripheral portion of the substrate, by a printing method using a screen plate, a metal mask, or the like. After being formed on a substrate or a roller, it can be formed by various conventionally known methods such as a transfer method of transferring onto a substrate.

In the multilayer liquid crystal display device of the present invention, including the multilayer liquid crystal display device shown in FIGS. 2 and 4, adjacent liquid crystal display devices may have a common substrate between them. FIG. 5 shows a state in which the substrates 1 and 2 between the adjacent liquid crystal display elements B and G and between the liquid crystal display elements G and R in the multilayer liquid crystal display element of FIG. Note that the pulse power supply 25 is not shown in FIG.

In the liquid crystal display device shown in FIGS.
By applying a predetermined voltage from 5, the liquid crystal 6 switches between a planar state (colored state) and a focal conic state (transparent state, black display state) to perform display.

In the multi-layer liquid crystal display device shown in FIGS. 2, 4 and 5, by applying a predetermined voltage from the power supply 25, the liquid crystal 6r, 6g, 6b has a planar state (colored state) and a focal conic state (colored state). (Transparent state). In the multi-layer liquid crystal display element, when all of the liquid crystals 6r, 6g, and 6b are in a colored state, white display is obtained, and when all of the liquid crystals are in a decolored state, black display is performed.

According to the liquid crystal display device described above, each of the liquid crystal compositions 6r, 6g, 6b, and 6 is a mixture of a chiral material and a nematic liquid crystal.
It is a chiral nematic liquid crystal composition containing 40% by weight. The nematic liquid crystal component has a refractive index anisotropy of 0.13 to 0.23, and an electro-optical threshold voltage (V) measured by a measurement method specified in JIS C7072.
10%) are all 0.50V to 1.10V, JIS
Each of the electro-optical saturation voltages (V90%) measured by the measuring method specified in C7072 is 1.15 V to 1.80 V.
Therefore, it is possible to drive at a low voltage, obtain a large light reflectance, and obtain a high contrast. Further, the practicable temperature range is wide.

As a chiral nematic liquid crystal composition,
The specific resistance of the nematic liquid crystal component contained therein is 5 × 1
The drive voltage to be applied to the liquid crystal display element is reduced because the one of 0 ¹⁰ (Ω · cm) to 5 × 10 ¹² (Ω · cm) is used. If the specific resistance is too high, the driving voltage tends to increase. Conversely, if it is too low, the display stability tends to decrease,
Alternatively, crosstalk, image defects, and image noise are likely to occur.

The nematic liquid crystal component has a refractive index anisotropy of 0.13 to 0.23. If the refractive index anisotropy is too low, the color purity of reflected light tends to deteriorate, and the light reflectance tends to decrease. Conversely, if it is too high, the viewing angle dependency tends to increase.

The electro-optical threshold voltage (V10%) of the nematic liquid crystal component and the electro-optical saturation voltage (V90)
%) Are 0.50 V to 1.10 V and 1.15 V, respectively.
However, if at least one of them is too high, the driving voltage applied to the liquid crystal display element tends to be high. Conversely, if at least one of them is too low, crosstalk, image defects, and image noise will occur. It is easy to occur.

Next, an experiment for evaluating the performance of the liquid crystal display device according to the present invention was conducted.
However, the present invention is not limited to those experimental examples.

In each of the following experimental examples, the refractive index anisotropy of the nematic liquid crystal component was measured at 25 ° C. using an Abbe refractometer.

The measured values of the threshold voltage and the saturation voltage were determined by JI
According to the measurement method defined in SC7072, a sandwich glass cell having a cell gap of 8 μm was used at 25 ° C.
, The relative luminance of white background black display is 0%, the relative luminance of black background white display is 100%, and the voltage at a relative luminance of 10% is a threshold voltage (V10%).
The voltage at a relative luminance of 90% was determined as a saturation voltage (V90%).

The measured value of the specific resistance was measured by using an LCR meter.
It was determined by applying a voltage of 5 V and 10 V.

The reflectance was measured by a reflection type spectrophotometer CM-3.
Luminous reflectance (Y value) using 700d (Minolta)
Was measured. The smaller the Y value, the more transparent. The contrast is given by (Y value in high reflectance state / Y value in low reflectance state). In the liquid crystal display element in each of the experimental examples described below, the liquid crystal display element enters a high reflectance state when the liquid crystal display element is in the planar state, and has a low reflectance state when the liquid crystal display element is in the focal conic state. (Experimental example 1) Nematic liquid crystal A (refractive index anisotropy Δn
0.195, threshold voltage (V10%) 1.05V, saturation voltage (V90%) 1.45V, specific resistance 1.2 × 10 ¹¹
Ω · cm), 33.3% by weight of a chiral material a (helical twist power (HTP): 10, the same applies to the chiral material a used in the following experiments) was mixed, and a chiral material having a selective reflection wavelength of 480 nm was mixed. A nematic liquid crystal composition a1 was prepared. The helical twist power (HTP) is shown as a value of a selective reflection wavelength of a liquid crystal composition obtained by adding 1% by weight of a chiral material to a nematic liquid crystal. The same applies to the following experimental examples and comparative experimental examples.

Each of ITO (indium tin oxide,
Two film substrates made of polycarbonate (PC) provided with a transparent electrode having a film thickness of 1400 ° and a sheet resistance of 80Ω / □ are prepared, and a 2000 mm thick oxidized film is formed on the ITO transparent electrode provided on one of the PC film substrates. silicon,
After forming an inorganic insulating film made of titanium oxide and zirconium oxide (manufactured by Catalyst Kasei Co., Ltd.), a thickness of 800 mm is formed thereon.
Was formed, and a 5 μm-diameter spacer (manufactured by Sekisui Fine Chemical Co., Ltd.) was sprayed thereon. Also, IT on another PC film substrate
On the O transparent electrode, an insulating film and an alignment film were formed in the same manner as on the one PC film substrate, and this was used as a counter substrate.

Subsequently, a sealing material (manufactured by Mitsui Chemicals, Inc.) was screen-printed on the periphery of the one substrate to form a wall having a predetermined height.

Then, after applying the liquid crystal composition a1 in an amount calculated from the height of the sealing material and the area of the portion surrounded by the sealing material on the one substrate, the two substrates are placed so that the electrode forming surfaces face each other. And heated while applying pressure from both sides of the substrate pair. Pressing and heating are performed, for example, by placing one substrate (11 in the figure) on a flat plate (91 in the figure) using a bonding apparatus shown in FIG. 9 and placing it on the other substrate (1 in the figure).
2) is superimposed, and is relatively passed between the roller 92 and the flat plate 91 while being heated and pressed by a heating / pressing roller (92 in the figure) from the end.
In FIG. 9, reference numerals 24 and 5 denote a seal wall and a spacer, respectively. Thus, both substrates are bonded together, and 150
Heating at 1 ° C. for 1 hour produced a liquid crystal cell (liquid crystal display element) A1.

Next, nematic liquid crystal B (refractive index anisotropy Δn 0.175, threshold voltage (V10%) 1.04
V, saturation voltage (V90%) 1.50 V, specific resistance 3.2 ×
25.4% by weight of chiral material b (helical twist power (HTP): 9, the same applies to chiral material b used in the following experiments) with respect to 10 ¹¹ Ω · cm).
A chiral nematic liquid crystal composition b1 having a selective reflection wavelength of 555 nm was prepared.

Two film substrates made of polycarbonate (PC) each provided with an ITO (film thickness: 1400 面, sheet resistance: 80 Ω / □) transparent electrode were prepared, and an ITO transparent electrode provided on one of the PC film substrates was prepared. To
After forming an inorganic insulating film (manufactured by Catalyst Chemicals Co., Ltd.) made of silicon oxide, titanium oxide and zirconium oxide having a thickness of 2,000 mm, a polyimide-based orientation film (manufactured by JSR) having a thickness of 800 mm is formed thereon. A 5 μm diameter spacer (manufactured by Sekisui Fine Chemical Co., Ltd.) was sprayed. Further, an insulating film and an orientation film were formed on the ITO transparent electrode on another PC film substrate in the same manner as on the one PC film substrate, and this was used as a counter substrate.

Subsequently, a sealing material (manufactured by Mitsui Chemicals, Inc.) was screen-printed on the periphery of the one substrate to form a wall having a predetermined height.

Then, the liquid crystal composition b1 is applied on the one substrate in an amount calculated from the height of the sealing material and the area of the portion surrounded by the sealing material, and the two substrates are bonded using the same bonding apparatus. The substrates were bonded together and heated at 150 ° C. for 1 hour to produce a liquid crystal cell (liquid crystal display element) B1.

Next, nematic liquid crystal C (refractive index anisotropy Δn 0.187, threshold voltage (V10%) 0.91
V, saturation voltage (V90%) 1.35 V, specific resistance 6.5 ×
18.6% by weight of a chiral material c (helical twist power (HTP): 12, the same applies to the chiral material c used in the following experiments) with respect to 10 ¹⁰ Ω · cm), and a selective reflection wavelength of 670 nm was obtained. The indicated chiral nematic liquid crystal composition c1 was prepared.

Two film substrates made of polycarbonate (PC) each provided with an ITO (film thickness: 1400 面, sheet resistance: 80 Ω / □) transparent electrode were prepared, and an ITO transparent electrode provided on one of the PC film substrates was prepared. To
After forming an inorganic insulating film (manufactured by Catalyst Chemicals Co., Ltd.) made of silicon oxide, titanium oxide and zirconium oxide having a thickness of 2,000 mm, a polyimide-based orientation film (manufactured by JSR) having a thickness of 800 mm is formed thereon. A 9 μm diameter spacer (manufactured by Sekisui Fine Chemical Co., Ltd.) was sprayed. Further, an insulating film and an orientation film were formed on the ITO transparent electrode on another PC film substrate in the same manner as on the one PC film substrate, and this was used as a counter substrate.

Subsequently, a sealing material (manufactured by Mitsui Chemicals, Inc.) was screen-printed on the periphery of the one substrate to form a wall having a predetermined height.

Thereafter, the liquid crystal composition c1 in an amount calculated from the height of the sealing material and the area of the portion surrounded by the sealing material is applied onto the one substrate, and the two substrates are bonded using the same bonding apparatus. The substrates were bonded together and heated at 150 ° C. for 1 hour to produce a liquid crystal cell (liquid crystal display element) C1.

The three types of liquid crystal cells A1, B1, C1
Were stacked in this order with the cell C1 facing down, and this was used as a multilayer liquid crystal display element. A black light-absorbing film was provided on the back surface of the multi-layer liquid crystal display element (the outer surface (back surface) of the liquid crystal cell C1).

When each cell was driven at a predetermined voltage in order to simultaneously bring the cells into a colored state and a decolored state, the Y value at the time of coloring observed from the liquid crystal cell A1 was 31.5, and the Y value at the time of black display was 5 0.0, and the contrast was 6.3: 1. Thus, a liquid crystal display device having good color / decoloration display characteristics and high contrast was obtained.

The driving voltage of the liquid crystal composition a1 was 35 V / 25 V in the colored state / decolored state, and the driving voltage was 32 V in the colored state / decolored state of the liquid crystal composition b1.
/ 20V, and the liquid crystal composition c1 was 38V / 27V in the colored state / decolored state, respectively. The driving voltage was measured using a pulse voltage of 5 msec. The same applies to the following experimental examples and comparative experimental examples. (Experimental example 2) Nematic liquid crystal D (refractive index anisotropy Δn
0.183, threshold voltage (V10%) 1.02V, saturation voltage (V90%) 1.54V, specific resistance 9.8 × 10 ¹⁰
(Ω · cm), 28.7% by weight of the chiral material a was mixed to prepare a chiral nematic liquid crystal composition d1 having a selective reflection wavelength of 480 nm.

Each of ITO (indium tin oxide,
Two film substrates made of polycarbonate (PC) provided with a transparent electrode having a film thickness of 1400 ° and a sheet resistance of 80Ω / □ are prepared, and a 2000 mm thick oxidized film is formed on the ITO transparent electrode provided on one of the PC film substrates. silicon,
After forming an inorganic insulating film made of titanium oxide and zirconium oxide (manufactured by Catalyst Kasei Co., Ltd.), a thickness of 800 mm is formed thereon.
Was formed, and a 5 μm-diameter spacer (manufactured by Sekisui Fine Chemical Co., Ltd.) was sprayed thereon. Also, IT on another PC film substrate
On the O transparent electrode, an insulating film and an alignment film were formed in the same manner as on the one PC film substrate, and this was used as a counter substrate.

Subsequently, a sealing material (manufactured by Mitsui Chemicals, Inc.) was screen-printed on the peripheral portion of the one substrate to form a wall having a predetermined height.

After that, the liquid crystal composition d1 was applied on the one substrate in an amount calculated from the height of the sealant and the area of the portion surrounded by the sealant, and then used for bonding the element of Experimental Example 1. The two substrates were bonded together using the same bonding apparatus as above, and heated at 150 ° C. for 1 hour to produce a liquid crystal cell (liquid crystal display element) D1.

Next, nematic liquid crystal F (refractive index anisotropy Δn 0.170, threshold voltage (V10%) 1.10)
V, saturation voltage (V90%) 1.55 V, specific resistance 4 × 10
¹¹ Ω · cm), 23.4% by weight of chiral material b
The mixture was mixed to prepare a chiral nematic liquid crystal composition f1 having a selective reflection wavelength of 555 nm.

Two film substrates each made of polycarbonate (PC) provided with an ITO (film thickness 1400 Å, sheet resistance 80 Ω / □) transparent electrode were prepared, and an ITO transparent electrode provided on one PC film substrate was prepared. To
After forming an inorganic insulating film (manufactured by Catalyst Chemicals Co., Ltd.) made of silicon oxide, titanium oxide and zirconium oxide having a thickness of 2,000 mm, a polyimide-based orientation film (manufactured by JSR) having a thickness of 800 mm is formed thereon. A 5 μm diameter spacer (manufactured by Sekisui Fine Chemical Co., Ltd.) was sprayed. Further, an insulating film and an orientation film were formed on the ITO transparent electrode on another PC film substrate in the same manner as on the one PC film substrate, and this was used as a counter substrate.

Subsequently, a sealing material (manufactured by Mitsui Chemicals, Inc.) was screen-printed on the peripheral portion of the one substrate to form a wall having a predetermined height.

Thereafter, the liquid crystal composition f1 in an amount calculated from the height of the sealing material and the area of the portion surrounded by the sealing material is applied onto the one substrate, and the two substrates are bonded using the same bonding apparatus. The substrates were bonded and heated at 150 ° C. for 1 hour to produce a liquid crystal cell (liquid crystal display element) F1.

Next, nematic liquid crystal G (refractive index anisotropy Δn 0.194, threshold voltage (V10%) 0.93
V, saturation voltage (V90%) 1.41 V, specific resistance 8.4 ×
The chiral material c was mixed at 12.1% by weight with respect to 10 ¹⁰ Ω · cm) to prepare a chiral nematic liquid crystal composition g1 having a selective reflection wavelength of 670 nm.

Two film substrates made of polycarbonate (PC) each provided with an ITO (film thickness: 1400 Å, sheet resistance: 80 Ω / □) transparent electrode were prepared, and an ITO transparent electrode provided on one of the PC film substrates was prepared. To
After forming an inorganic insulating film (manufactured by Catalyst Chemicals Co., Ltd.) made of silicon oxide, titanium oxide and zirconium oxide having a thickness of 2,000 mm, a polyimide-based orientation film (manufactured by JSR) having a thickness of 800 mm is formed thereon. An 8 μm diameter spacer (manufactured by Sekisui Fine Chemical Co., Ltd.) was sprayed. Further, an insulating film and an orientation film were formed on the ITO transparent electrode on another PC film substrate in the same manner as on the one PC film substrate, and this was used as a counter substrate.

Subsequently, a sealing material (manufactured by Mitsui Chemicals, Inc.) was screen-printed on the periphery of the one substrate to form a wall having a predetermined height.

Thereafter, the liquid crystal composition g1 in an amount calculated from the height of the sealing material and the area of the portion surrounded by the sealing material is applied onto the one substrate, and the two substrates are bonded using the same bonding apparatus. The substrates were bonded together and heated at 150 ° C. for 1 hour to produce a liquid crystal cell (liquid crystal display element) G1.

These three types of liquid crystal cells D1, F1, G1
Were stacked in this order with the cell G1 facing down, and this was used as a multilayer liquid crystal display element. A black light-absorbing film was provided on the back surface of the multi-layer liquid crystal display element (the outer surface (back surface) of the liquid crystal cell G1).

When the cells were simultaneously driven at a predetermined voltage to bring them into a colored state and a decolored state, the Y value at the time of coloring observed from the liquid crystal cell D1 was 30.7, and the Y value at the time of black display was 5 .1, the contrast was 6.0: 1, and the liquid crystal display device was excellent in both coloration and decoloration display characteristics and high in contrast.

The driving voltage of the liquid crystal composition d1 was 33 V / 22 V in the colored state / decolored state, and the driving voltage of the liquid crystal composition f1 was 32 V in the colored state / decolorized state.
/ 20 V, and the liquid crystal composition g1 was 36 V / 25 V in the colored state / decolored state, respectively. (Experimental example 3) Nematic liquid crystal H (refractive index anisotropy Δn)
0.177, threshold voltage (V10%) 0.98V, saturation voltage (V90%) 1.40V, specific resistance 7.5 × 10 ¹⁰
(Ω · cm), 26.9% by weight of the chiral material a was mixed to prepare a chiral nematic liquid crystal composition h1 having a selective reflection wavelength of 485 nm.

Each of ITO (indium tin oxide,
Two film substrates made of polycarbonate (PC) provided with a transparent electrode having a film thickness of 1400 ° and a sheet resistance of 80Ω / □ are prepared, and a 2000 mm thick oxidized film is formed on the ITO transparent electrode provided on one of the PC film substrates. silicon,
After forming an inorganic insulating film made of titanium oxide and zirconium oxide (manufactured by Catalyst Kasei Co., Ltd.), a thickness of 800 mm is formed thereon.
Was formed, and a 5 μm-diameter spacer (manufactured by Sekisui Fine Chemical Co., Ltd.) was sprayed thereon. Also, IT on another PC film substrate
On the O transparent electrode, an insulating film and an alignment film were formed in the same manner as on the one PC film substrate, and this was used as a counter substrate.

Subsequently, a sealing material (manufactured by Mitsui Chemicals, Inc.) was screen-printed on the periphery of the one substrate to form a wall having a predetermined height.

Thereafter, the liquid crystal composition h1 was applied in an amount calculated from the height of the sealing material and the area of the portion surrounded by the sealing material on the one substrate, and then applied to the device of Experimental Example 1. The two substrates were bonded together using the same bonding apparatus as above, and heated at 150 ° C. for 1 hour to produce a liquid crystal cell (liquid crystal display element) H1.

Next, the nematic liquid crystal I (refractive index anisotropy Δn 0.180, threshold voltage (V10%) 1.06
V, saturation voltage (V90%) 1.45 V, specific resistance 3.7 ×
Chiral material d (helical twist power (HTP): 22, the same applies to chiral material d used in the following experiments) and chiral material e (helical twist power (10 ¹¹ Ω · cm)). HTP): 11) was mixed at 7% by weight to prepare a chiral nematic liquid crystal composition i1 having a selective reflection wavelength of 555 nm.

Two film substrates made of polycarbonate (PC) each provided with an ITO (film thickness 1400 Å, sheet resistance 80 Ω / □) transparent electrode were prepared, and an ITO transparent electrode provided on one of the PC film substrates was prepared. To
After forming an inorganic insulating film (manufactured by Catalyst Chemicals Co., Ltd.) made of silicon oxide, titanium oxide and zirconium oxide having a thickness of 2,000 mm, a polyimide-based orientation film (manufactured by JSR) having a thickness of 800 mm is formed thereon. A 5 μm diameter spacer (manufactured by Sekisui Fine Chemical Co., Ltd.) was sprayed. Further, an insulating film and an orientation film were formed on the ITO transparent electrode on another PC film substrate in the same manner as on the one PC film substrate, and this was used as a counter substrate.

Subsequently, a sealing material (manufactured by Mitsui Chemicals, Inc.) was screen-printed on the periphery of the one substrate to form a wall having a predetermined height.

Thereafter, the liquid crystal composition i1 in an amount calculated from the height of the sealing material and the area of the portion surrounded by the sealing material is applied to the one substrate, and the two substrates are bonded using the same bonding apparatus. The substrates were bonded together and heated at 150 ° C. for 1 hour to produce a liquid crystal cell (liquid crystal display element) I1.

Next, a nematic liquid crystal J (refractive index anisotropy Δn 0.20, threshold voltage (V10%) 0.89 V,
Saturation voltage (V90%) 1.39V, specific resistance 6.4 × 10
¹⁰ Ω · cm), 13.5% by weight of chiral material c
And 6% by weight of a chiral material d, and a selective reflection wavelength of 67
A chiral nematic liquid crystal composition j1 exhibiting 5 nm was prepared.

Two film substrates made of polycarbonate (PC) each having an ITO (film thickness 1400 Å, sheet resistance 80 Ω / □) transparent electrode were prepared, and an ITO transparent electrode provided on one of the PC film substrates was prepared. To
After forming an inorganic insulating film made of silicon oxide, titanium oxide and zirconium oxide having a thickness of 2000 mm (manufactured by Kasei Kasei Co., Ltd.), a polyimide-based orientation film having a thickness of 800 mm (manufactured by JSR Corporation) is formed thereon. A 7 μm diameter spacer (manufactured by Sekisui Fine Chemical Co., Ltd.) was sprayed. Further, an insulating film and an orientation film were formed on the ITO transparent electrode on another PC film substrate in the same manner as on the one PC film substrate, and this was used as a counter substrate.

Subsequently, a sealing material (manufactured by Mitsui Chemicals, Inc.) was screen-printed on the periphery of the one substrate to form a wall having a predetermined height.

Thereafter, the liquid crystal composition j1 is applied on the one substrate in an amount calculated from the height of the sealing material and the area of the portion surrounded by the sealing material, and the two substrates are bonded using the same bonding apparatus. The substrates were bonded and heated at 150 ° C. for 1 hour to produce a liquid crystal cell (liquid crystal display element) J1.

These three types of liquid crystal cells H1, I1, J1
Were stacked in this order with the cell J1 facing down, and this was used as a multilayer liquid crystal display element. A black light-absorbing film was provided on the back surface of this multilayer liquid crystal display element (the outer surface (back surface) of the liquid crystal cell J1).

When each cell was driven at a predetermined voltage in order to simultaneously bring the colored state and the decolored state, the Y value at the time of coloring observed from the liquid crystal cell H1 was 30.3, and the Y value at the time of black display was 4 0.8, and the contrast was 6.3: 1, and a liquid crystal display device having good color / decoloration display characteristics and high contrast was obtained.

The driving voltage of the liquid crystal composition h1 was 35 V / 20 V in the colored state / decolored state, and the driving voltage of the liquid crystal composition i1 was 38 V in the colored state / decolorized state.
/ 24V, and the liquid crystal composition j1 was 39V / 25V in the colored state / decolored state, respectively. (Experimental example 4) Nematic liquid crystal K (refractive index anisotropy Δn)
0.22, threshold voltage (V10%) 1.08V, saturation voltage (V90%) 1.75V, specific resistance 2.4 × 10 ¹¹ Ω
· Cm), 29.5% by weight of the chiral material a was mixed to prepare a chiral nematic liquid crystal composition k1 having a selective reflection wavelength of 470 nm.

Each of ITO (indium tin oxide,
Two film substrates made of polycarbonate (PC) provided with a transparent electrode having a film thickness of 1400 ° and a sheet resistance of 80Ω / □ are prepared, and a 2000 mm thick oxidized film is formed on the ITO transparent electrode provided on one of the PC film substrates. silicon,
After forming an inorganic insulating film made of titanium oxide and zirconium oxide (manufactured by Catalyst Kasei Co., Ltd.), a thickness of 800 mm is formed thereon.
Was formed, and a 4 μm-diameter spacer (manufactured by Sekisui Fine Chemical Co., Ltd.) was sprayed thereon. Also, IT on another PC film substrate
On the O transparent electrode, an insulating film and an alignment film were formed in the same manner as on the one PC film substrate, and this was used as a counter substrate.

Subsequently, a sealing material (manufactured by Mitsui Chemicals, Inc.) was screen-printed on the periphery of the one substrate to form a wall having a predetermined height.

Thereafter, an amount of the liquid crystal composition k1 calculated from the height of the sealing material and the area of the portion surrounded by the sealing material was applied onto the one substrate, and then used for bonding the element of Experimental Example 1. The two substrates were bonded together using the same bonding apparatus as above, and heated at 150 ° C. for 1 hour to produce a liquid crystal cell (liquid crystal display element) K1.

Next, nematic liquid crystal L (refractive index anisotropy Δn 0.165, threshold voltage (V10%) 1.01
V, saturation voltage (V90%) 1.47 V, specific resistance 7.8 ×
10 ¹¹ Ω · cm) and 25.3% by weight of a chiral material b were mixed to prepare a chiral nematic liquid crystal composition 11 having a selective reflection wavelength of 560 nm.

Two film substrates each made of polycarbonate (PC) provided with an ITO (film thickness 1400 Å, sheet resistance 80 Ω / □) transparent electrode were prepared, and an ITO transparent electrode provided on one PC film substrate was prepared. To
After forming an inorganic insulating film (manufactured by Catalyst Chemicals Co., Ltd.) made of silicon oxide, titanium oxide and zirconium oxide having a thickness of 2,000 mm, a polyimide-based orientation film (manufactured by JSR) having a thickness of 800 mm is formed thereon. A 5 μm diameter spacer (manufactured by Sekisui Fine Chemical Co., Ltd.) was sprayed. Further, an insulating film and an orientation film were formed on the ITO transparent electrode on another PC film substrate in the same manner as on the one PC film substrate, and this was used as a counter substrate.

Subsequently, a sealing material (manufactured by Mitsui Chemicals, Inc.) was screen-printed on the periphery of the one substrate to form a wall having a predetermined height.

Then, the liquid crystal composition 11 was applied on the one substrate in an amount calculated from the height of the sealing material and the area of the portion surrounded by the sealing material, and the two substrates were bonded using the same bonding apparatus. The substrates were bonded together and heated at 150 ° C. for 1 hour to produce a liquid crystal cell (liquid crystal display element) L1.

Next, a nematic liquid crystal M (refractive index anisotropy Δn 0.21, threshold voltage (V10%) 0.97 V,
Saturation voltage (V90%) 1.48 V, specific resistance 2.6 × 10
Against ^{11 Ω} · cm), a chiral agent c 18.6 wt%
The mixture was mixed to prepare a chiral nematic liquid crystal composition m1 having a selective reflection wavelength of 670 nm.

Two film substrates made of polycarbonate (PC) each having an ITO (film thickness: 1400 面, sheet resistance: 80 Ω / □) transparent electrode were prepared, and an ITO transparent electrode provided on one PC film substrate was prepared. To
After forming an inorganic insulating film (manufactured by Catalyst Chemicals Co., Ltd.) made of silicon oxide, titanium oxide and zirconium oxide having a thickness of 2,000 mm, a polyimide-based orientation film (manufactured by JSR) having a thickness of 800 mm is formed thereon. A 7 μm diameter spacer (manufactured by Sekisui Fine Chemical Co., Ltd.) was sprayed. Further, an insulating film and an orientation film were formed on the ITO transparent electrode on another PC film substrate in the same manner as on the one PC film substrate, and this was used as a counter substrate.

Subsequently, a sealing material (manufactured by Mitsui Chemicals, Inc.) was screen-printed on the periphery of the one substrate to form a wall having a predetermined height.

Thereafter, the liquid crystal composition m1 in an amount calculated from the height of the sealing material and the area of the portion surrounded by the sealing material is applied onto the one substrate, and the two substrates are bonded using the same bonding apparatus. The substrates were bonded and heated at 150 ° C. for 1 hour to produce a liquid crystal cell (liquid crystal display element) M1.

These three types of liquid crystal cells K1, L1, M1
Were stacked in this order with the cell M1 facing down, and this was used as a multilayer liquid crystal display element. A black light-absorbing film was provided on the back surface of this multilayer liquid crystal display element (the outer surface (back surface) of the liquid crystal cell M1).

When each cell was driven at a predetermined voltage to simultaneously bring the colored state and the decolored state, the Y value at the time of coloring observed from the liquid crystal cell K1 was 29.8, and the Y value at the time of black display was 5 1.1, the contrast was 5.8: 1, and the liquid crystal display device was excellent in both coloration and decoloration display characteristics and high in contrast.

The driving voltage of the liquid crystal composition k1 was 38 V / 20 V in the colored state / decolorized state, and the driving voltage of the liquid crystal composition 11 was 35 V in the colored state / decolorized state.
/ 18 V, and the liquid crystal composition m1 was 38 V / 24 V in the colored state / decolored state, respectively. (Experimental example 5) Nematic liquid crystal N (refractive index anisotropy Δn)
0.205, threshold voltage (V10%) 0.54V, saturation voltage (V90%) 1.15V, specific resistance 5 × 10 ¹⁰ Ω ·
cm), 38% by weight of a chiral material a was mixed to prepare a chiral nematic liquid crystal composition n1 having a selective reflection wavelength of 470 nm.

Each of ITO (indium tin oxide,
Two film substrates made of polycarbonate (PC) provided with a transparent electrode having a film thickness of 1400 ° and a sheet resistance of 80Ω / □ are prepared, and a 2000 mm thick oxidized film is formed on the ITO transparent electrode provided on one of the PC film substrates. silicon,
After forming an inorganic insulating film made of titanium oxide and zirconium oxide (manufactured by Catalyst Kasei Co., Ltd.), a thickness of 800 mm is formed thereon.
Was formed, and a 4 μm-diameter spacer (manufactured by Sekisui Fine Chemical Co., Ltd.) was sprayed thereon. Also, IT on another PC film substrate
On the O transparent electrode, an insulating film and an alignment film were formed in the same manner as on the one PC film substrate, and this was used as a counter substrate.

Subsequently, a sealing material (manufactured by Mitsui Chemicals, Inc.) was screen-printed on the peripheral portion of the one substrate to form a wall having a predetermined height.

Thereafter, the liquid crystal composition n1 was applied on the one substrate in an amount calculated from the height of the sealing material and the area of the portion surrounded by the sealing material. The two substrates were bonded together using the same bonding apparatus as above, and heated at 150 ° C. for 1 hour to produce a liquid crystal cell (liquid crystal display element) N1.

Next, nematic liquid crystal O (refractive index anisotropy Δn 0.163, threshold voltage (V10%) 0.78
V, saturation voltage (V90%) 1.27 V, specific resistance 4.3 ×
10 ¹¹ Ω · cm), 10% by weight of chiral material b
And 17% by weight of chiral material d, and selectively reflected wavelength 5
A chiral nematic liquid crystal composition o1 exhibiting 60 nm was prepared.

Two film substrates made of polycarbonate (PC) each having an ITO (film thickness: 1400 Å, sheet resistance: 80Ω / □) transparent electrode were prepared. To
After forming an inorganic insulating film (manufactured by Catalyst Chemicals Co., Ltd.) made of silicon oxide, titanium oxide and zirconium oxide having a thickness of 2,000 mm, a polyimide-based orientation film (manufactured by JSR) having a thickness of 800 mm is formed thereon. A 5 μm diameter spacer (manufactured by Sekisui Fine Chemical Co., Ltd.) was sprayed. Further, an insulating film and an orientation film were formed on the ITO transparent electrode on another PC film substrate in the same manner as on the one PC film substrate, and this was used as a counter substrate.

Subsequently, a sealing material (manufactured by Mitsui Chemicals, Inc.) was screen-printed on the periphery of the one substrate to form a wall having a predetermined height.

Thereafter, the liquid crystal composition o1 was applied on the one substrate in an amount calculated from the height of the sealing material and the area of the portion surrounded by the sealing material, and the two substrates were bonded using the same bonding apparatus. The substrates were bonded and heated at 150 ° C. for 1 hour to produce a liquid crystal cell (liquid crystal display element) O1.

Next, the nematic liquid crystal P (refractive index anisotropy Δn 0.225, threshold voltage (V10%) 1.07
V, saturation voltage (V90%) 1.65 V, specific resistance 4.1 ×
With respect to 10 ¹² Ω · cm), 7.3% by weight of a chiral material f (helical twist power (HTP): 5) was mixed.
A chiral chiral nematic liquid crystal composition p1 exhibiting a selective reflection wavelength of 670 nm was prepared.

Two film substrates made of polycarbonate (PC) each having an ITO (film thickness 1400 Å, sheet resistance 80 Ω / □) transparent electrode were prepared, and an ITO transparent electrode provided on one PC film substrate was prepared. To
After forming an inorganic insulating film (manufactured by Catalyst Chemicals Co., Ltd.) made of silicon oxide, titanium oxide and zirconium oxide having a thickness of 2,000 mm, a polyimide-based orientation film (manufactured by JSR) having a thickness of 800 mm is formed thereon. A 7 μm diameter spacer (manufactured by Sekisui Fine Chemical Co., Ltd.) was sprayed. Further, an insulating film and an orientation film were formed on the ITO transparent electrode on another PC film substrate in the same manner as on the one PC film substrate, and this was used as a counter substrate.

Subsequently, a sealing material (manufactured by Mitsui Chemicals, Inc.) was screen-printed on the periphery of the one substrate to form a wall having a predetermined height.

Thereafter, the liquid crystal composition p1 in an amount calculated from the height of the sealing material and the area of the portion surrounded by the sealing material is applied to the one substrate, and the two substrates are bonded using the same bonding apparatus. The substrates were bonded and heated at 150 ° C. for 1 hour to produce a liquid crystal cell (liquid crystal display element) P1.

These three types of liquid crystal cells N1, O1, P1
Were stacked in this order with the cell P1 facing down, and this was used as a multilayer liquid crystal display element. A black light-absorbing film was provided on the back surface of the multi-layer liquid crystal display element (the outer surface (back surface) of the liquid crystal cell P1).

When the cells were simultaneously driven at a predetermined voltage to bring the cells into a colored state and a decolored state, the Y value at the time of coloring observed from the liquid crystal cell N1 was 31.6, and the Y value at the time of black display was 5 .4, and the contrast was 5.9: 1, and the liquid crystal display device had good coloration / decoloration display characteristics and high contrast.

The driving voltage of the liquid crystal composition n1 was 36 V / 18 V in the colored state / decolored state, and the driving voltage of the liquid crystal composition o1 was 34 V in the colored state / decolorized state.
/ 15V, and the liquid crystal composition p1 was 37V / 20V in the colored state / decolored state, respectively. (Experimental example 6) Nematic liquid crystal Q (refractive index anisotropy Δn
0.171, threshold voltage (V10%) 0.98 V, saturation voltage (V90%) 1.45 V, specific resistance 1.3 × 10 ¹¹
(Ω · cm), 25.4% by weight of the chiral material b was mixed to prepare a chiral nematic liquid crystal composition q1 having a selective reflection wavelength of 555 nm.

Each of ITO (indium tin oxide,
Prepare two glass substrates provided with a transparent electrode having a thickness of 1400 ° and a sheet resistance of 80Ω / □, and form a polyimide alignment film having a thickness of 800 ° on an ITO transparent electrode provided on one of the glass substrates. A 5 μm diameter spacer (manufactured by Sekisui Fine Chemical Co., Ltd.) was sprayed thereon. Also, an alignment film is formed on the ITO transparent electrode on another glass substrate in the same manner as on the one glass substrate.
This was used as a counter substrate.

Subsequently, a seal material (manufactured by Sekisui Chemical Co., Ltd.) was screen-printed on the peripheral portion of the one substrate, and then both substrates were bonded together and thermally cured at 150 ° C. for 1 hour.

Thereafter, the liquid crystal composition q1 was obtained by a vacuum injection method.
, A sealing material Photolec (manufactured by Sekisui Chemical Co., Ltd.) was applied to the liquid crystal injection port, and the liquid crystal was sealed by irradiating ultraviolet rays to produce a liquid crystal cell (liquid crystal display element) Q1.

A black light absorbing film was provided on the back surface of the liquid crystal cell.

When the cell was driven at a predetermined voltage to bring the cell into a colored state and a decolored state, the Y value in the colored state was 21.
5. When displaying black, the Y value is 1.3, and the contrast is 16.
The ratio was 5: 1, and the liquid crystal display device had good coloration / decoloration display characteristics and high contrast.

The driving voltage was 33 V / 16 V in the colored state / decolored state, respectively. (Experimental example 7) Nematic liquid crystal R (refractive index anisotropy Δn)
0.185, threshold voltage (V10%) 0.95V, saturation voltage (V90%) 1.39V, specific resistance 4.5 × 10 ¹¹
Ω · cm), 32.5% by weight of chiral material g (helical twist power (HTP): 10, the same applies to chiral material g used in the following experiments) and 2.9% by weight of chiral material a. % To prepare a chiral nematic liquid crystal composition r1 exhibiting a selective reflection wavelength of 480 nm.

Each of ITO (indium tin oxide,
Prepare two glass substrates provided with a transparent electrode having a thickness of 1400 ° and a sheet resistance of 80Ω / □, and form a polyimide-based alignment film having a thickness of 800 ° on an ITO transparent electrode provided on one of the glass substrates. A 5 μm diameter spacer (manufactured by Sekisui Fine Chemical Co., Ltd.) was sprayed thereon. Also, an alignment film is formed on the ITO transparent electrode on another glass substrate in the same manner as on the one glass substrate,
This was used as a counter substrate.

Subsequently, after a seal material (manufactured by Sekisui Chemical Co., Ltd.) was screen-printed on the periphery of the one substrate, the two substrates were bonded together and thermally cured at 150 ° C. for 1 hour.

Thereafter, the liquid crystal composition r1 was obtained by a vacuum injection method.
, A sealing material Photolec (manufactured by Sekisui Chemical Co., Ltd.) was applied to the liquid crystal injection port, and the liquid crystal was sealed by irradiating ultraviolet rays to produce a liquid crystal cell (liquid crystal display element) R1.

A black light absorbing film was provided on the back surface of the liquid crystal cell.

When the cell was driven at a predetermined voltage to bring the cell into a colored state and a decolored state, the Y value at the time of coloring was 14.
6. When displaying black, the Y value is 1.5, and the contrast is 9.
The ratio was 7: 1, and the liquid crystal display device had good color / decoloration display characteristics and high contrast.

The driving voltage was 32 V / 15 V in the colored state / decolored state, respectively. (Comparative Experimental Example 1) Nematic liquid crystal S (refractive index anisotropy Δ
n0.142, threshold voltage (V10%) 1.20V,
Saturation voltage (V90%) 2.03V, specific resistance 6 × 10 ¹² Ω
・ Cm), 32% by weight of chiral material a is mixed,
A chiral nematic liquid crystal composition s1 having a selective reflection wavelength of 480 nm was prepared.

Each of ITO (indium tin oxide,
Prepare two glass substrates provided with a transparent electrode having a thickness of 1400 ° and a sheet resistance of 80Ω / □, and form a polyimide-based alignment film having a thickness of 800 ° on an ITO transparent electrode provided on one of the glass substrates. A 5 μm diameter spacer (manufactured by Sekisui Fine Chemical Co., Ltd.) was sprayed thereon. Also, an alignment film is formed on the ITO transparent electrode on another glass substrate in the same manner as on the one glass substrate.
This was used as a counter substrate.

Subsequently, after a seal material (manufactured by Sekisui Chemical Co., Ltd.) was screen-printed on the peripheral portion of the one substrate, the two substrates were bonded together and thermally cured at 150 ° C. for 1 hour.

Thereafter, the liquid crystal composition s1 was formed by a vacuum injection method.
, A sealing material Photolec (manufactured by Sekisui Chemical Co., Ltd.) was applied to the liquid crystal injection port, and the liquid crystal was sealed by irradiating ultraviolet rays to produce a liquid crystal cell (liquid crystal display element) S1.

A black light absorbing film was provided on the back surface of the liquid crystal cell.

When the cell was driven at a predetermined voltage to bring the cell into a colored state and a decolored state, the Y value at the time of coloring was 9.3.
When displaying black, the Y value is 1.8 and the contrast is 5.2: 1.
And the driving voltage is 6 in each of the colored state and the decolored state.
0 V / 34 V.

The refractive index anisotropy of the nematic liquid crystal is low.
Because of the high threshold voltage, a liquid crystal display element with poor color / decoloration display characteristics and low contrast was obtained. Further, the driving voltage was increased. (Comparative Experimental Example 2) Nematic liquid crystal T (refractive index anisotropy Δ
n0.185, threshold voltage (V10%) 1.25 V,
Saturation voltage (V90%) 2.14 V, specific resistance 1.1 × 10
¹³ Ω · cm), 34% by weight of chiral material a was mixed to prepare a chiral nematic liquid crystal composition t1 having a selective reflection wavelength of 480 nm.

Each of ITO (indium tin oxide,
Prepare two glass substrates provided with a transparent electrode having a thickness of 1400 ° and a sheet resistance of 80Ω / □, and form a polyimide-based alignment film having a thickness of 800 ° on an ITO transparent electrode provided on one of the glass substrates. A 5 μm diameter spacer (manufactured by Sekisui Fine Chemical Co., Ltd.) was sprayed thereon. Also, an alignment film is formed on the ITO transparent electrode on another glass substrate in the same manner as on the one glass substrate.
This was used as a counter substrate.

Subsequently, a seal material (manufactured by Sekisui Chemical Co., Ltd.) was screen-printed on the peripheral portion of one of the substrates, and then both substrates were bonded together and thermally cured at 150 ° C. for 1 hour.

Thereafter, the liquid crystal composition t1 was obtained by a vacuum injection method.
Was injected, a sealing material Photolec (manufactured by Sekisui Chemical Co., Ltd.) was applied to the liquid crystal injection port, and the liquid crystal was sealed by irradiating ultraviolet rays to produce a liquid crystal cell (liquid crystal display element) T1.

A black light absorbing film was provided on the back surface of the liquid crystal cell.

When the cell was driven at a predetermined voltage to bring the cell into a colored state and a decolored state, the Y value at the time of coloring was 13.
2. When displaying black, the Y value is 1.6, and the contrast is 8.
The drive voltage was 70 V / 36 V in the colored state / decolored state, respectively.

Since the threshold voltage of the nematic liquid crystal was high, a liquid crystal display device having a high driving voltage was obtained. (Comparative Experimental Example 3) Nematic liquid crystal U (refractive index anisotropy Δ
n0.168, threshold voltage (V10%) 1.05V,
Saturation voltage (V90%) 1.66V, specific resistance 4 × 10 ¹¹ Ω
・ Cm), 51% by weight of chiral material g is mixed,
A chiral nematic liquid crystal composition u1 having a selective reflection wavelength of 470 nm was prepared.

Each of ITO (indium tin oxide,
Prepare two glass substrates provided with a transparent electrode having a thickness of 1400 ° and a sheet resistance of 80Ω / □, and form a polyimide alignment film having a thickness of 800 ° on an ITO transparent electrode provided on one of the glass substrates. A 5 μm diameter spacer (manufactured by Sekisui Fine Chemical Co., Ltd.) was sprayed thereon. Also, an alignment film is formed on the ITO transparent electrode on another glass substrate in the same manner as on the one glass substrate.
This was used as a counter substrate.

Subsequently, a sealing material (manufactured by Sekisui Chemical Co., Ltd.) was screen-printed on the peripheral portion of one of the substrates, and then both substrates were bonded together and thermally cured at 150 ° C. for 1 hour.

Thereafter, the liquid crystal composition u1 was prepared by a vacuum injection method.
, A sealing material Photolec (manufactured by Sekisui Chemical Co., Ltd.) was applied to the liquid crystal injection port, and the liquid crystal was sealed by irradiating ultraviolet rays to produce a liquid crystal cell (liquid crystal display element) U1.

A black light absorbing film was provided on the back surface of the liquid crystal cell.

When the cell was driven at a predetermined voltage to bring the cell into a colored state and a decolored state, the Y value at the time of coloring was 12.
5. When displaying black, the Y value is 1.9, and the contrast is 6.
6: 1, and the drive voltage was 55 V / 30 V in the colored state / decolored state, respectively.

Since the content of the chiral material was large, a liquid crystal display device having a low contrast and a high driving voltage was obtained. (Comparative Experimental Example 4) Nematic liquid crystal V (refractive index anisotropy Δ
n0.140, threshold voltage (V10%) 1.21 V,
Saturation voltage (V90%) 2.16 V, specific resistance 5.2 × 10
¹² Ω · cm), 34% by weight of chiral material a was mixed to prepare a chiral nematic liquid crystal composition v1 having a selective reflection wavelength of 480 nm.

Each of ITO (indium tin oxide,
Two film substrates made of polycarbonate (PC) provided with a transparent electrode having a film thickness of 1400 ° and a sheet resistance of 80Ω / □ are prepared, and a 2000 mm thick oxidized film is formed on the ITO transparent electrode provided on one of the PC film substrates. silicon,
After forming an inorganic insulating film made of titanium oxide and zirconium oxide (manufactured by Catalyst Kasei Co., Ltd.), a thickness of 800 mm is formed thereon.
Was formed, and a 5 μm-diameter spacer (manufactured by Sekisui Fine Chemical Co., Ltd.) was sprayed thereon. Also, IT on another PC film substrate
On the O transparent electrode, an insulating film and an alignment film were formed in the same manner as on the one PC film substrate, and this was used as a counter substrate.

Subsequently, a sealing material (manufactured by Mitsui Chemicals, Inc.) was screen-printed on the periphery of the one substrate to form a wall having a predetermined height.

Thereafter, an amount of the liquid crystal composition v1 calculated from the height of the sealing material and the area of the portion surrounded by the sealing material was applied onto the one substrate, and then applied to the device of Experimental Example 1. The two substrates were bonded together using the same bonding apparatus as above, and heated at 150 ° C. for 1 hour to produce a liquid crystal cell (liquid crystal display element) V1.

Next, the nematic liquid crystal W (refractive index anisotropy Δn 0.145, threshold voltage (V10%) 1.07
V, saturation voltage (V90%) 1.48 V, specific resistance 6.8 ×
26% by weight of chiral material b with respect to 10 ¹¹ Ω · cm)
After mixing, a chiral nematic liquid crystal composition w1 having a selective reflection wavelength of 550 nm was prepared.

[0175] Two film substrates made of polycarbonate (PC) each provided with an ITO (film thickness 1400 Å, sheet resistance 80 Ω / □) transparent electrode were prepared, and an ITO transparent electrode provided on one PC film substrate was prepared. To
After forming an inorganic insulating film (manufactured by Catalyst Chemicals Co., Ltd.) made of silicon oxide, titanium oxide and zirconium oxide having a thickness of 2,000 mm, a polyimide-based orientation film (manufactured by JSR) having a thickness of 800 mm is formed thereon. A 5 μm diameter spacer (manufactured by Sekisui Fine Chemical Co., Ltd.) was sprayed. Further, an insulating film and an orientation film were formed on the ITO transparent electrode on another PC film substrate in the same manner as on the one PC film substrate, and this was used as a counter substrate.

Subsequently, a sealing material (manufactured by Mitsui Chemicals, Inc.) was screen-printed on the periphery of the one substrate to form a wall having a predetermined height.

Thereafter, an amount of the liquid crystal composition w1 calculated from the height of the sealing material and the area of the portion surrounded by the sealing material is applied onto the one substrate, and the two substrates are bonded using the same bonding apparatus. The substrates were bonded together and heated at 150 ° C. for 1 hour, thereby producing a liquid crystal cell (liquid crystal display element) W1.

Next, nematic liquid crystal X (refractive index anisotropy Δn 0.167, threshold voltage (V10%) 1.31)
V, saturation voltage (V90%) 2.15 V, specific resistance 6.5 ×
The chiral material c was mixed at 19.5% by weight with respect to 10 ¹² Ω · cm) to prepare a chiral nematic liquid crystal composition x1 having a selective reflection wavelength of 670 nm.

[0179] Two film substrates made of polycarbonate (PC) each provided with an ITO (film thickness 1400 Å, sheet resistance 80Ω / □) transparent electrode were prepared, and an ITO transparent electrode provided on one of the PC film substrates was prepared. To
After forming an inorganic insulating film (manufactured by Catalyst Chemicals Co., Ltd.) made of silicon oxide, titanium oxide and zirconium oxide having a thickness of 2,000 mm, a polyimide-based orientation film (manufactured by JSR) having a thickness of 800 mm is formed thereon. A 9 μm diameter spacer (manufactured by Sekisui Fine Chemical Co., Ltd.) was sprayed. Further, an insulating film and an orientation film were formed on the ITO transparent electrode on another PC film substrate in the same manner as on the one PC film substrate, and this was used as a counter substrate.

Subsequently, a sealing material (manufactured by Mitsui Chemicals, Inc.) was screen-printed on the periphery of the one substrate to form a wall having a predetermined height.

After that, the liquid crystal composition x1 in an amount calculated from the height of the sealing material and the area of the portion surrounded by the sealing material was applied onto the one substrate, and the two substrates were bonded using the same bonding apparatus. The substrates were bonded and heated at 150 ° C. for 1 hour to produce a liquid crystal cell (liquid crystal display element) X1.

These three types of liquid crystal cells V1, W1, X1
Were stacked in this order with the cell X1 facing down, and this was used as a multilayer liquid crystal display element. A black light-absorbing film was provided on the back surface of the multi-layer liquid crystal display element (the outer surface (back surface) of the liquid crystal cell X1).

When the cells were simultaneously driven at a predetermined voltage to bring the cells into the colored state and the decolored state, the Y value observed from the liquid crystal cell V1 at the time of coloring was 26.1, and the Y value at the time of black display was 6 .5, the contrast was 4.0: 1, and the liquid crystal display device with low contrast and poor color / erasing display characteristics was obtained.

The driving voltage of the liquid crystal composition v1 was 55 V / 32 V in the colored state / decolored state, and the driving voltage was 40 V in the colored state / decolored state of the liquid crystal composition w1.
/ 25 V, and the liquid crystal composition x1 was 65 V / 40 V in the colored state / decolored state, respectively, and a liquid crystal display device having a high driving voltage was obtained.

As described above, all of the liquid crystal display devices of Experimental Examples 1 to 7 were able to be driven at a low voltage, and were good in both coloration and decoloration display characteristics and high in contrast. On the other hand, the driving voltages of the liquid crystal display elements of Comparative Experimental Examples 1 to 4 were all high. Further, the single-layer liquid crystal display element for performing blue display in Comparative Experimental Examples 1 to 3 is different from the single-layer liquid crystal display element for performing blue display in Experimental Example 7 in the multilayer liquid crystal display element in Comparative Experimental Example 4. Was lower in contrast than the multilayer liquid crystal display devices of Experimental Examples 1 to 5.

[0186]

As described above, according to the present invention, a liquid crystal display device in which a liquid crystal layer containing a liquid crystal composition exhibiting a cholesteric phase at room temperature is sandwiched between a pair of substrates, can be driven at a low voltage, and It is possible to provide a liquid crystal display element which can obtain a large light reflectance, has a high contrast, and has a wide practical temperature range.

Further, according to the present invention, a multi-layer liquid crystal display which can be driven at a low voltage, is bright, has good contrast, and has a wide practical temperature range, in which a plurality of liquid crystal display elements including at least one such liquid crystal display element are stacked. An element can be provided.

[Brief description of the drawings]

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

FIG. 2 is another example of a liquid crystal display element according to the present invention, in which a liquid crystal display element for performing blue display, a liquid crystal display element for performing green display, and a liquid crystal display element for performing red display are arranged in this order. It is a schematic sectional drawing of the laminated | stacked liquid crystal display element laminated.

FIG. 3 shows a state where only spacers are used as space holding members in the liquid crystal display element shown in FIG.

FIG. 4 is a diagram showing a state in which only a spacer is used as a space holding member in the liquid crystal display element shown in FIG.

FIG. 5 is a view showing a state in which a substrate between the adjacent liquid crystal display elements is shared in the multilayer liquid crystal display element of FIG. 4;

FIG. 6 is a view showing an example of an arrangement state of a resin structure provided in the liquid crystal display element according to the present invention.

FIG. 7 is a view showing an example of a bonding apparatus for bonding a pair of substrates to manufacture a liquid crystal display device according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 2 A pair of board | substrates 3 Light absorption layer 4 Resin structure 5 Spacer 6, 6b, 6g, 6r Liquid crystal composition 7 Insulating film 8 Alignment stabilization film 10, 10b, 10g, 10r Liquid crystal layer 11, 12 Transparent electrode 25 pulse Power supply 91 Flat plate 92 Heating / pressing roller B, G, R Liquid crystal display element S Sealing material

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Noboru Ueda 2-3-113 Azuchicho, Chuo-ku, Osaka-shi, Osaka Inside Osaka International Building Minolta Co., Ltd. 2-13-13 Azuchicho Osaka International Building Minolta Co., Ltd. F-term (reference) 2H088 GA02 GA03 GA17 KA24 MA02 2H089 HA31 QA16 RA03 4H027 BA02 BD05 BD07 BD14 BE01 BE02 BE03

Claims (7)

[Claims] 1. A liquid crystal display device having a liquid crystal layer containing a liquid crystal composition exhibiting a cholesteric phase at room temperature between a pair of substrates with electrodes, wherein the liquid crystal composition contains a mixture of a chiral material and a nematic liquid crystal. A chiral nematic liquid crystal composition containing the material in an amount of 7% by weight to 40% by weight with respect to the entire liquid crystal composition, wherein the nematic liquid crystal component has a refractive index anisotropy of 0.13 to 0.23 according to JIS C7072. Electro-optical threshold voltage (V10
%) Is 0.50 V to 1.10 V, and an electro-optical saturation voltage (V9) measured by a measurement method specified in JIS C7072.
(0%) is 1.15 V to 1.80 V. 2. The liquid crystal according to claim 1, wherein said chiral nematic liquid crystal composition has a selective reflection wavelength in a red wavelength range at room temperature and contains a chiral material in an amount of 7 to 25% by weight based on the whole liquid crystal composition. Display element. 3. The liquid crystal according to claim 1, wherein the chiral nematic liquid crystal composition has a selective reflection wavelength in a green wavelength region at room temperature, and contains 10% to 30% by weight of a chiral material based on the whole liquid crystal composition. Display element. 4. The liquid crystal according to claim 1, wherein said chiral nematic liquid crystal composition has a selective reflection wavelength in a blue wavelength range at room temperature, and contains 15 to 40% by weight of a chiral material based on the whole liquid crystal composition. Display element. 5. The nematic liquid crystal component has a specific resistance of 5 ×.
^{10 10 (Ω · cm) ~5} × 10 12 (Ω · cm) liquid crystal display device according to any one of claims 1 to 4. 6. The liquid crystal display device according to claim 1, wherein at least one of said pair of substrates is a substrate made of a resin material. 7. A multilayer liquid crystal display device comprising a plurality of liquid crystal layers sandwiched between a pair of substrates, wherein at least one of the plurality of liquid crystal layers sandwiches the liquid crystal layer. A multilayer liquid crystal display device comprising the liquid crystal display device according to claim 1 together with a pair of substrates to be formed.