JP2002162648A - Liquid crystal device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal device provided with a liquid crystal element having uniform switching characteristics and high contrast. SOLUTION: The liquid crystal element 70 is provided with a pair of substrates 81a and 81b sandwiching a liquid crystal 85 and disposed opposite to each other so that the directions of uniaxial alignment treatment of the substrates are parallel and opposite to each other, the liquid crystal 85 showing a chiral smectic phase having >=4.pretilt angle on at least one substrate and polarizing plates 87a and 87b provided on at least the one substrate side. Such external voltage that the product Ps×Erms of the spontaneous polarization value (Ps) that the liquid crystal 85 has and the effective value electric field (Erms) applied to the liquid crystal 85 satisfies the relational formula Ps×Erms>15 [(nC/cm2)×(V/um)], is applied to the liquid crystal element 70 for a prescribed period or longer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal device used for a light valve used in a flat panel display, a projection display, a printer, etc., and more particularly to a device having a liquid crystal element using a liquid crystal exhibiting a chiral smectic phase. .

[0002]

2. Description of the Related Art Conventionally, a TFT (Thin Film T)
Typical liquid crystal modes of a nematic liquid crystal display element widely used as a display element using an active element such as a ransistor are, for example, "M. Schadt" and "W. Helfrich", by W. Helfrich. Applied Phys
sics Letters Vol. 18, No. 4 (1971
Published on February 15, 2008) ", pages 127 to 128.
e) mode is widely used.

On the other hand, recently, in-plane switching (In-Plane Switch) using a lateral electric field has been proposed.
hing) mode and vertical alignment (Vertical A)
A liquid crystal display using a (ligent) mode has been announced, and the viewing angle characteristic, which has been a drawback of the conventional liquid crystal display, has been improved.

As described above, there are several liquid crystal modes for use in a TFT display element using such a nematic liquid crystal. In any of these modes, the response speed of the liquid crystal is several tens of milliseconds or more. Therefore, further improvement in response speed is required.

In order to improve the response speed of such a conventional nematic liquid crystal element, several liquid crystal modes using a liquid crystal exhibiting a chiral smectic phase have been proposed in recent years. For example, "short pitch type ferroelectric liquid crystal", "polymer stable type ferroelectric liquid crystal", "thresholdless antiferroelectric liquid crystal" and the like have been proposed,
Although not yet in practical use, it has been reported that any of them can achieve high-speed response of sub-millisecond or less.

On the other hand, we have invented and proposed an element described in Japanese Patent Application No. 10-177145 (hereinafter referred to as a prior application element). Here, this prior application element shows, for example, an isotropic liquid phase (ISO.)-Cholesteric phase (Ch) -chiral smectic C phase or an isotropic liquid phase (ISO.)-Chiral smectic C phase from the high temperature side. Focusing on the phase series material, monostabilization is performed at a position inside the edge of the virtual cone.

[0007] For example, during the Ch-SmC * phase transition or the I-phase-SmC * phase transition, a positive or negative DC voltage is applied between a pair of substrates to uniform the layer direction in one direction. As a result, a high-speed response and gradation control can be performed, and a high-brightness liquid crystal element excellent in moving image quality can be realized with high mass productivity.

Since the spontaneous application element can reduce the spontaneous polarization value as compared with the above-mentioned various smectic liquid crystal modes, it is an element having good matching with an active element such as a TFT.

As described above, a chiral smectic liquid crystal, in particular, a liquid crystal device using a prior-art element has been realized in the sense that the problem relating to the response speed of a TFT liquid crystal display using a nematic liquid crystal can be solved. Expected. As described above, the smectic liquid crystal element of the prior application, which has a gradation display capability for a next-generation display or the like such as a high-speed response performance, is expected.

[0010]

However, in the above-mentioned prior application element which is an example of such a conventional liquid crystal element, the C1 alignment appears in a part of the C2 aligned liquid crystal panel in the alignment control. Sometimes. On the other hand, Japanese Patent Application No. 10-177145 recommends the use of a low pretilt alignment film in order to reduce the difference in characteristics between the C2 orientation and the C1 orientation. In any case, even if a slight pretilt exists, a difference in characteristics between the C2 orientation and the C1 orientation is unavoidable, causing in-plane variations in the voltage-transmittance characteristics.

On the other hand, when a rubbed cell is used in a low pretilt angle alignment film in order to avoid such in-plane variation, and the alignment control force of the cell is set within a predetermined range, Japanese Patent Application Publication No. A stripe texture as described in 84639 is observed. When such an orientation is realized, in-plane variation based on the difference between the C1 orientation and the C2 orientation as described above does not occur, so that uniform switching characteristics can be easily obtained over the entire panel. it can.

However, in the case of such an alignment state, slight light leakage occurs even in a black state (in a state where no voltage is applied), so that it is conceivable that the contrast is not essentially large enough.

Further, in the liquid crystal device of Japanese Patent Application No. 11-84639, molecular inversion by so-called micro-domain switching is performed as a response to a voltage.
Note that the microdomain has a shape having anisotropy such as a rectangular shape or an elliptical shape. If the minor axis at this time is 10 μm or less, the microdomains are not visually recognized individually, but are continuously visible. It is visually recognized as gradation.

Here, the micro domain does not cause a serious problem when the liquid crystal element is used in a direct-view type liquid crystal monitor, but the liquid crystal element such as a projector, a view finder, or a head mounted display using an enlarged projection system is used. When used in a device, the micro domain is naturally enlarged and displayed, so image quality degradation,
In particular, it was a cause of a feeling of roughness. In addition, even in the direct-view type liquid crystal monitor, in the current trend of high definition, if the pixel pitch becomes less than 100 μm, the situation that the gradation display capability within one pixel cannot be guaranteed depending on the domain distribution may occur. Maybe.

The present invention has been made in view of such circumstances, and has as its object to provide a liquid crystal device having a liquid crystal element having uniform switching characteristics and high contrast.

[0016]

According to the present invention, a liquid crystal exhibiting a chiral smectic phase is sandwiched, an electrode for applying a voltage to the liquid crystal is provided, and a uniaxial alignment treatment for aligning the liquid crystal is performed. A liquid crystal device including a liquid crystal element including a pair of substrates and a polarizing plate provided on at least one substrate side, wherein the pair of substrates of the liquid crystal element has uniaxial alignment directions parallel and opposite. The liquid crystal has a pretilt angle of at least one substrate of 4 ° or more, and the liquid crystal element has a spontaneous polarization value (Ps) of the liquid crystal and an effective voltage applied to the liquid crystal. Ps · Erms with the value electric field (Erms)
Ps · Erms> 15 [(nC / cm ² ) · (V / u
m)] is applied for a predetermined time or more.

Further, in the present invention, the phase transition series of the liquid crystal is isotropic liquid phase (ISO.)-Cholesteric phase (Ch) -chiral smectic C phase or isotropic liquid phase (ISO.)-Chiral from the high temperature side. It is a smectic C phase.

The present invention is also characterized in that, when the external voltage is applied, the applied external voltage has a waveform that changes with time.

Further, the present invention is characterized in that the application of the external voltage is performed during a start-up period from immediately after the power is turned on until an image is displayed.

Further, the present invention is characterized in that the application of the external voltage is performed during a screen saver period.

Further, the present invention is characterized in that the application of the external voltage is periodically performed at a predetermined timing.

The present invention is characterized in that the external light source is substantially turned off during the application of the external voltage.

Further, according to the present invention, the liquid crystal shows a first state in which the average molecular axis of the liquid crystal is monostable when no voltage is applied, and the average molecular axis of the liquid crystal is applied when a voltage of the first polarity is applied. Is tilted to one side from the monostable position at an angle corresponding to the magnitude of the applied voltage, and when a voltage of a second polarity opposite to the first polarity is applied, the average molecular axis of the liquid crystal is Is tilted from the monostable position to the side opposite to the case where the first polarity voltage is applied, and the average of the liquid crystal when the first polarity voltage is applied and when the second polarity voltage is applied. The tilt angle of the maximum tilt state of the molecular axis with respect to the mono-stabilized position in the first state is β1,
When β2, β1> β2.

In the present invention, the tilt angles β1, β
2 is characterized in that β1 ≧ 5 × β2.

Further, the present invention is characterized in that it has a driving circuit for driving the liquid crystal element, and a backlight light source.

Further, the present invention is characterized in that it has a driving circuit for driving the liquid crystal element and a reflector.

Further, the present invention is characterized in that the drive circuit has an active element provided on the substrate and performing an active matrix drive.

Further, as in the present invention, a pair of substrates which sandwich a liquid crystal and are opposed to each other so that the directions of the uniaxial orientation treatment are parallel and opposite to each other, and at least one substrate which exhibits a chiral smectic phase and Is applied to a liquid crystal element having a liquid crystal having a pretilt angle of 4 ° or more and a polarizing plate provided on at least one of the substrates, and an effective value electric field applied to the liquid crystal. The product Ps · Erms with (Erms) is Ps · Erms> 15 [(nC / cm ² ) · (V / u
m)] is applied for a predetermined time or more.

[0029]

Embodiments of the present invention will be described below.

FIG. 1 is a sectional view showing the structure of a liquid crystal device having a liquid crystal element according to an embodiment of the present invention. In FIG. 1, reference numeral 70 denotes a liquid crystal device, and 80 denotes a pair of liquid crystal devices whose polarization axes are orthogonal to each other. It is a liquid crystal element sandwiched between polarizing plates 87a and 87b. The liquid crystal element 80 is formed on a substrate 8 made of a pair of highly transparent materials such as glass and plastic.
A liquid crystal 85, preferably a liquid crystal exhibiting a chiral smectic phase, is sandwiched between 1a and 81b.

Here, the substrates 81a and 81b are respectively provided with In ₂ O ₃ and ITO for applying a voltage to the liquid crystal 85.
The electrodes 82a and 82b made of a material such as the like are provided. For example, as will be described later, dot-shaped transparent electrodes are arranged in a matrix on one substrate, and a TFT or MIM (Metal-Insulator-Meta
1) and the like, and an opposing electrode having a predetermined pattern is formed on one surface of the other substrate to form an active matrix structure.

On the electrodes 82a, 82b, insulating films 83a, 83b made of a material such as SiO ₂ , TiO ₂ , Ta ₂ O ₅ having a function of preventing short-circuiting are provided as necessary. Provided respectively, and further provided with an insulating film 83.
On the a and 83b, alignment control films 84a and 84b which are in contact with the liquid crystal 85 and function to control the alignment state thereof are provided.

Here, the orientation control films 84a and 84b are subjected to a uniaxial orientation treatment. The alignment control films 84a and 84b are, for example, those obtained by subjecting the surface of a film obtained by applying a solution to an organic material such as polyimide, polyimide amide, polyamide, or polyvinyl alcohol to a rubbing treatment,
Alternatively, it is formed of an obliquely deposited film of an inorganic material obtained by depositing an oxide or a nitride such as SiO at a predetermined angle from an oblique direction with respect to the substrate.

Furthermore, the orientation control films 84a and 84b may be selected depending on the selection of the material and the conditions of the treatment (uniaxial orientation treatment or the like), etc., depending on the pretilt angle of the molecules of the liquid crystal 85 (the film near the interface of the liquid crystal molecules. Angle to the plane) is adjusted.

When the orientation control films 84a and 84b are both uniaxially oriented films, the uniaxial orientation direction (especially the rubbing direction) of each film is parallel or anti-parallel depending on the liquid crystal material used. Alternatively, it can be set to cross in the range of 45 ° or less.

The substrates 81a and 81b face each other with a spacer 86 interposed therebetween. The spacer 86 determines the distance (cell gap) between the substrates 81a and 81b, and silica beads or the like are used.

The optimum range and upper limit of the cell gap determined by the spacers 86 are different depending on the liquid crystal material. However, the uniform uniaxial orientation and the average molecular axis of the liquid crystal molecules when no voltage is applied are determined. In order to develop an alignment state that is substantially the same as the average direction axis of the alignment processing axis, it is preferable to set the range of 0.3 to 10 μm. Further, it is preferable that the value of the cell thickness is appropriately adjusted and set so that the retardation amount when no voltage is applied is a desired amount.

In addition to the spacer 86, in order to improve the adhesiveness between the substrates 81a and 81b and to improve the impact resistance of the liquid crystal 85 exhibiting a chiral smectic phase, adhesive particles made of a resin material such as an epoxy resin are used. They can also be distributed (not shown).

On the other hand, in such a liquid crystal element 80, when a liquid crystal exhibiting a chiral smectic phase is used as the liquid crystal 85, the composition of the material is adjusted, and further, the processing of the liquid crystal material and the element configuration, for example, the alignment control film 84a , 84
By appropriately setting the material of b, processing conditions, and the like, when no voltage is applied, the liquid crystal shows an alignment state in which the average molecular axis of the liquid crystal (liquid crystal molecules) is monostable, and when driving, one polarity (first Of the average molecular axis, the tilt angle changes continuously according to the magnitude of the applied voltage, and the voltage of the other polarity (second polarity) is applied. Sometimes, the average molecular axis of the liquid crystal exhibits characteristics such that it tilts at an angle corresponding to the magnitude of the applied voltage.

Further, in the present embodiment, the maximum tilt angle β1 by applying the voltage of the first polarity is larger than the maximum tilt angle β2 by applying the voltage of the second polarity, that is, β1 ≧ 5 × The characteristic that becomes β2 is shown.

As the liquid crystal material exhibiting such a chiral smectic phase, the characteristics of the above-mentioned prior application element (physical property cone angle Θ inherent to the liquid crystal material, the layer spacing d of the smectic layer, and the characteristics of the inclination angle δ) ), A biphenyl skeleton or a phenylcyclohexane ester skeleton,
A composition prepared by appropriately selecting a hydrocarbon-based liquid crystal material having a phenylpyrimidine skeleton or the like, a naphthalene-based liquid crystal material, or a polyfluorine-based liquid crystal material is used.

Further, these liquid crystal materials are disclosed in Japanese Patent Application No.
No. 177145, the phase transition series is isotropic liquid phase (ISO.)-Cholesteric phase (Ch) -chiral smectic C phase (Sm).
C *) or an isotropic liquid phase (ISO.)-Chiral smectic C phase (SmC *).

In the liquid crystal element 80 using such a liquid crystal, a transition between the pair of substrates occurs during the transition to the SmC * phase.
By applying either positive or negative DC voltage, it is aligned in only one of the two layer directions, that is, the deviation direction between the average uniaxial orientation processing axis and the normal direction of the smectic layer is constant, and no voltage is applied. In the added state, the liquid crystal molecule is stabilized inside the virtual cone edge, and its memory property is lost.
The orientation state of the mC * phase is obtained.

Further, the liquid crystal material has a phase transition series in which the isotropic liquid phase (ISO) -cholesteric phase (C
h) -Chiral smectic C phase or isotropic liquid phase (ISO) -chiral smectic C phase is preferred. Hereinafter, specific examples of preferable compounds constituting the liquid crystal composition used in the present invention are shown in (1) to (4).

[0045]

Embedded image R1, R2: a linear or branched alkyl group which may have a substituent having 1 to 20 carbon atoms X1, X2: single bond, O, COO, OOC Y1, Y2, Y3, Y4: H or F n: 0 or 1

[0046]

Embedded image R1, R2: a linear or branched alkyl group which may have a substituent having 1 to 20 carbon atoms X1, X2: single bond, O, COO, OOC Y1, Y2, Y3, Y4: H or F

[0047]

Embedded image R1, R2: a linear or branched alkyl group which may have a substituent having 1 to 20 carbon atoms X1, X2: single bond, O, COO, OOC Y1, Y2, Y3, Y4: H or F

[0048]

Embedded image R1, R2: a linear or branched alkyl group which may have a substituent having 1 to 20 carbon atoms X1, X2: single bond, O, COO, OOC Y1, Y2, Y3, Y4: H or F

The liquid crystal device 7 according to the present embodiment
At 0, a drive circuit for supplying a gradation signal to the liquid crystal element 80 shown in FIG. 1 is provided, and a continuous tilt angle from the monostable position of the average molecular axis of the liquid crystal by applying a voltage as described above. And a characteristic in which the amount of light emitted from the liquid crystal element 80 continuously changes is used to perform gradation display.

For example, by using an active matrix substrate provided with a TFT or the like as described above as one substrate of the liquid crystal element 80 and performing active matrix driving by amplitude modulation with a drive circuit, analog gray scale display is possible. .

Next, a gray scale display using such an active matrix substrate will be described with reference to FIGS.

FIG. 2 is a diagram schematically showing the structure of one substrate (active matrix substrate) of the liquid crystal element 80. As shown in FIG.
0, horizontal gate lines G1 and G2 corresponding to the scanning lines connected to the scanning signal driver 91 as the driving means.
, G5 and a vertical source line S1, corresponding to an information signal line connected to an information signal driver 92 as a driving means.
, S5 are provided so as to be orthogonal to each other while being insulated from each other.

Further, these gate lines G1, G2,.
, S5, and source lines S1, S2,..., S5.
FT) 94 and a pixel electrode 95 are provided (only the area of 5 × 5 pixels is shown in the figure for simplicity). As a switching element, an MIM element can be used in addition to a TFT.

The gate lines G1, G2,.
The source lines S1, S2,..., S5 are connected to the source electrode (not shown) of the TFT 94, and the pixel electrode 15 is connected to the drain electrode (not shown) of the TFT 94. Have been.

Then, in the substrate having such a configuration,
The gate lines G1, G2,.
5 are, for example, line-sequentially scanned and supplied with a gate voltage, and information corresponding to information to be written to each pixel from the information signal driver 92 in synchronization with the scanning selection of the gate lines G1, G2,. The signal voltage is applied to the source lines S1, S2
.., S5, and each pixel electrode 1
5 is applied.

On the other hand, FIG. 3 is a diagram showing an example of a sectional structure of each pixel portion (for one bit) in the panel configuration as shown in FIG. 2. In the structure shown in FIG. Active matrix substrate 20 provided
And a counter substrate 40 having a common electrode 32, a liquid crystal layer 49 having spontaneous polarization is interposed therebetween, and a liquid crystal capacitor (C1
c) 31 is constituted. In this active matrix substrate 20, an amorphous S
iTFT is used.

Here, the TFT 94 is formed on the substrate 21 made of glass or the like, and the gate lines G1 and G1 shown in FIG.
An a-Si layer 24 is provided on a gate electrode 22 connected to G2... G5 via an insulating film (gate insulating film) 23 made of a material such as silicon nitride (SiNx). A source electrode 27 and a drain electrode 28 are provided above each other with n ⁺ a-Si layers 25 and 26 interposed therebetween.

The source electrode 27 is connected to the source lines S1, S2,..., S5 shown in FIG.
It is connected to a pixel electrode 95 made of a transparent conductive film such as a TO film. The channel protection film 29 covers the a-Si layer 24 of the TFT 94. Furthermore, this TFT
Reference numeral 94 denotes an ON state in which a gate pulse is applied to the gate electrode 22 during a period in which the corresponding gate line is selected for scanning.

On the other hand, in the active matrix substrate 20, the insulating film 23 (the film provided continuously with the insulating film on the gate electrode 22) is formed by the pixel electrode 95 and the storage capacitor electrode 30 provided on the glass substrate 21 side. ), The storage capacitor (CS) 32 is provided in parallel with the liquid crystal layer 49. When the area of the storage capacitor electrode 30 is large, the aperture ratio is reduced. Therefore, the storage capacitor electrode 30 is formed of a transparent conductive film such as an ITO film.

The T of the active matrix substrate 20
On the FT 94 and the pixel electrode 95, there is provided an alignment film 43 a which has been subjected to a uniaxial alignment process such as a rubbing process for controlling the alignment state of the liquid crystal 49.
0 on the glass substrate 41 having the same thickness as the common electrode 4 on the entire surface.
2 and an alignment film 43b. In the panel configuration shown in FIGS. 2 and 3, a polycrystalline Si (p-Si) TFT is used as the active matrix substrate 20.
Can be used.

Next, an active matrix drive utilizing the characteristics of the liquid crystal device having the above structure will be described with reference to FIGS. FIG. 4 shows an equivalent circuit of a pixel portion of the panel shown in FIG. FIG. 5 is a diagram showing an applied voltage and an optical response for driving the liquid crystal element.

In the active matrix driving according to the present embodiment, for example, a period (one frame) for displaying certain information in one pixel is divided into a plurality of fields (for example, 1F and 2F shown in FIG. 5). In two fields, an output light amount according to predetermined information is obtained on average.

Hereinafter, an example in which the liquid crystal layer 49 is divided into two fields in a case where the transmission light intensity is sufficient when a voltage of one polarity is applied and the transmission light intensity is smaller when the polarity is opposite, will be described. .

Here, FIG. 5A shows a voltage applied to one gate line which is a scanning line connected to the pixel when focusing on one pixel. In the liquid crystal element having the above structure, as described above, the gate lines G1, G
, G5 are selected, for example, line-sequentially, a predetermined gate voltage Vg is applied to one gate line during the selection period Ton, a voltage Vg is applied to the gate electrode 22, and a TFT 94 is selected.
Is turned on.

In a non-selection period Toff corresponding to a period in which another gate line is selected, no voltage is applied to the gate electrode 22 and the TFT 12 is in a high resistance state (OFF state). The same gate line is selected and the gate voltage Vg is applied to the gate electrode 22.

FIG. 5B shows the voltage Vs applied to the information signal line (source line) of the pixel. And FIG.
As shown in (a), when a gate voltage is applied to the gate electrode 22 in the selection period Ton in each field, the source lines S1 and S serving as information lines connected to the pixel are synchronized with the application of the gate voltage.
A predetermined source voltage (information signal voltage) Vs (a reference potential is a potential Vc of the common electrode 42) is applied to the source electrode 27 from S2, S5.

Here, in the first field (1F) constituting one frame, optical information to be obtained in the pixel based on information written in the pixel, for example, voltage-transmittance characteristics according to the liquid crystal used. A positive source voltage (information signal voltage) of level Vx according to the state or display information (transmittance) is applied.

At this time, since the TFT 94 is in the ON state, the voltage Vx applied to the source electrode 27 is applied to the pixel electrode 95 via the drain electrode 28, and the liquid crystal capacitance (C1c) 31 and the storage capacitance (Cs) 32 is charged, and the potential of the pixel electrode becomes the information signal voltage Vx.

Subsequently, during the non-selection period Toff of the gate line to which the pixel belongs, the TFT 94 has a high resistance (OFF state).
During this non-selection period, the liquid crystal cell (liquid crystal capacitor C
1c) 31 and the storage capacitor (Cs) 32 in the selection period To
n while maintaining the state where the charge charged at
x is retained. As a result, the voltage Vx is applied to the liquid crystal layer 49 in the pixel throughout the first field 1F, and an optical state (transmitted light amount) corresponding to this voltage value is obtained in the liquid crystal portion of the pixel.

On the other hand, at this time, if the response speed of the liquid crystal is slower than the gate-on period, the liquid crystal cell (liquid crystal capacitor C1c) 31
Then, the charging of the storage capacitor (Cs) 32 is completed, and switching is started in the non-selection period in which the gate is turned off. In such a case, the charged electric charge is canceled by the reversal of the spontaneous polarization, and the voltage value Vpix applied to the liquid crystal layer 49 takes a value of Vx ′ smaller than Vx as shown in FIG.

Next, in the selection period Ton of the second field (2F), the source voltage (-Vx) having the polarity opposite to that of the first field 1F and having substantially the same voltage value Vx.
Is applied to the source electrode 27. At this time, the TFT 94 is in the ON state, the voltage −Vx is applied to the pixel electrode 95, and the liquid crystal capacitance (C 1 c) 31 and the storage capacitance (Cs) 32
And the potential of the pixel electrode is changed to the information signal voltage −Vx.
become.

Subsequently, during the non-selection period Toff, TF
Since T94 has a high resistance (OFF state), during this non-selection period, the liquid crystal cell (liquid crystal capacitance C1c) 31 and the storage capacitance (Cs) 32 maintain the state where the charges charged during the selection period Ton are accumulated. Then, the voltage -Vx is maintained.

Then, the voltage -Vx is applied to the liquid crystal layer 49 in the pixel throughout the second field 2F, and the pixel obtains an optical state (light emission amount) corresponding to the voltage value. At this time, similarly, when the response speed of the liquid crystal is lower than the gate-on period, the liquid crystal cell (liquid crystal capacitance C1
c) The charging of 31 and the storage capacitor (Cs) 32 is completed, and switching is started during the non-selection period in which the gate is turned off.

In such a case, the charged electric charge is canceled by the reversal of the spontaneous polarization, and the voltage value Vpix applied to the liquid crystal layer 49 is smaller than -Vx as shown in FIG.
Take the value VX '.

On the other hand, as shown in (d), in the first field 1F, a gradation display state (light emission amount) according to Vx is obtained, and in the second field 2F, a gradation display state according to -Vx '. However, in practice, only a slight change in the amount of transmitted light is obtained, and the amount of transmitted light is smaller than Tx and becomes Ty close to the 0 level.

In such active matrix driving, when a liquid crystal exhibiting a chiral smectic phase is used, gradation display based on good high-speed response can be performed, and at the same time, a certain level of gradation display can be performed with one pixel. Is divided into a first field 1F for obtaining a high transmitted light amount and a second field 2F for obtaining a low transmitted light amount, and is continuously performed.
The time aperture ratio becomes 50% or less, and the moving image high-speed response characteristic perceived by human eyes is also improved. Further, in the second field 2F, the transmitted light amount does not become completely zero due to the slight switching operation of the liquid crystal molecules, so that the brightness perceived by human eyes during the entire frame period is secured.

Further, the first and second fields 1F, 2F
Since the voltage at the same level is inverted and applied to the liquid crystal layer 49, the voltage actually applied to the liquid crystal layer 49 is converted into an alternating current, thereby preventing the deterioration of the liquid crystal.

As described above, in the above-described active matrix driving, T is applied to the entire frame composed of two fields.
Since the transmitted light amount obtained by averaging x and Ty is obtained, the transmitted light amount of the information signal voltage Vs is increased by a predetermined level according to the image information (gradation information) to be actually obtained by the pixel in the frame. By selecting and applying a voltage value capable of obtaining a gray level, it is possible to display a gray scale state with a higher level of transmitted light than a desired gray scale state in the first field 1F.

The gray scale display by the active matrix drive is performed by using a light-transmitting substrate 81a as shown in FIG.
81b and a pair of polarizing plates, not only a transmissive liquid crystal element of a type that modulates light incident from one substrate side by a backlight (not shown) and emits the light to the other side, but also at least one substrate A reflective liquid crystal element having a polarizing plate provided thereon, that is, a reflective plate is provided on one of the substrates 81a and 81b, or a reflective material is used as one of the substrates themselves or a member provided on the substrate. The present invention can also be applied to an element of a type that modulates reflected light and emits light to the same side as the incident side.

The present invention can also be applied to a color liquid crystal element in which at least one of R, G and B color filters is provided on one of the substrates 81a and 81b. Furthermore, as a light source,
By sequentially switching the R, G, and B light sources, a method of performing full-color display using color mixture by time division can be used.

By the way, as described above, in the prior-art element of the prior art, the C1 and C2 orientations or the orientation showing a stripe texture have been used.
1. C2 orientation makes it difficult to avoid unevenness in switching characteristics in the panel plane, and orientation exhibiting a striped texture essentially realizes a sufficiently high contrast although switching characteristic unevenness in the panel plane is not observed. The alignment state was difficult.

Therefore, in the present invention, a liquid crystal element uses a substrate having a slightly higher pretilt angle as compared with the prior application element in which at least one of the substrates has a pretilt angle of 4 ° or more, and a pair of substrates is anti-parallel, that is, A pair of substrates are combined so that the rubbing directions are parallel and opposite to each other. In use, the spontaneous polarization value of the liquid crystal is Ps, and the effective value electric field applied to the liquid crystal element is Es.
rms, at least a predetermined time (1 second or more) Ps · Erms> 15 [(nC / cm ² ) · (V / u
m)] is applied.

Then, the pair of substrates is combined in an anti-parallel manner, and at least a predetermined time Ps
Erms> 15 [(nC / cm ² ) · (V / um)]
By applying the external voltage, it is possible to achieve both the non-uniformity of the switching characteristics in the panel surface and the high contrast ratio.

The pretilt angle in the present invention is
When the liquid crystal material used has a Ch phase, the pretilt angle at the lower limit temperature of the Ch phase is used, and when the liquid crystal material has no Ch phase, the pretilt angle at the upper limit temperature of the SmC * phase is used. This is because the value of the pretilt angle that affects the layer inclination angle when the layer structure is formed for the first time in the temperature lowering process is most important.

In the case where the measurement at the above temperature is difficult,
If it is confirmed that the temperature dependency of the pretilt angle is not or extremely small, the measurement may be performed at any other temperature. Alternatively, a liquid crystal material having a similar composition ratio is prepared, and the Ch phase or SmA of the liquid crystal is prepared.
It is also possible to substitute the pretilt angle in the phase.

The pretilt angle is determined by the crystal rotation method Opn. J. Appl. Phys, Vo.
119 (1980) No. 10. Short Note
s2013). Here, two substrates are bonded to each other in the cell for measurement in the crystal rotation method such that the inclination of the liquid crystal at the interface between the upper and lower substrates is parallel and in the same direction (rubbing axes are parallel and opposite directions: anti-parallel). Produced.

In the measurement procedure in the crystal rotation method, the liquid crystal cell is rotated on a plane perpendicular to the upper and lower substrates and including the alignment processing axis (rubbing axis), and has a light-supplying surface that forms an angle of 450 with the rotation axis. A helium-neon laser beam is irradiated from a direction perpendicular to the rotation axis, and the transmitted light intensity is measured by a photodiode through a polarizing plate having a transmission axis parallel to the incident polarization plane on the opposite side.

Then, the pretilt angle α can be obtained by performing a simulation by fitting the spectrum of the transmitted light intensity generated by the interference with a theoretical curve, equations (1) and (2).

[0089]

(Equation 1) N ₀ : ordinary light refractive index N _e : extraordinary light refractive index φ: rotation angle of liquid crystal panel T (φ): transmitted light intensity d: cell thickness λ: wavelength of incident light

[0090]

(Equation 2)

Next, a layer structure forming model when a substrate having a high pretilt angle is used and antiparallel rubbing conditions are used will be described in comparison with a conventional example.

It is considered that the bookshelf structure is formed in the cell structure using the conventional low pretilt substrate immediately after the phase transition to the smectic phase (immediately after the layer is formed). Thereafter, as the temperature goes down, the layer interval decreases, and the layer changes to a structure inclined from the normal direction of the substrate. At this time, in the case of a chevron structure, C1 or C2 orientation is formed.

On the other hand, in the prior application element described in Japanese Patent Application No. 11-84639, a stripe texture is formed by appropriately adjusting the alignment regulating force.
The layer structure has an oblique bookshelf structure.
Also in this case, although a bookshelf structure is probably formed immediately after the Ch-SmC * phase transition, if the orientation control force is within a predetermined range, the layer interval decreases in the temperature lowering process and the layer becomes a substrate. When changing from a normal direction to an inclined structure, it is thought that an oblique bookshelf structure is formed instead of a chevron. At this time, it is considered that a subtle non-uniformity of the layer structure generated in the process of changing the layer tilt angle is observed as a stripe texture.

On the other hand, like the liquid crystal element of the present invention,
In the case of a layer structure model using a substrate with a slightly higher pretilt angle and antiparallel rubbing conditions, the layer is already in an oblique book form immediately after the phase transition to the smectic phase (immediately after the layer is formed). It can be easily inferred that a shelf structure is formed.

That is, since the oblique bookshelf structure is formed from the initial stage of the phase transition, it is considered that the layer structure is less likely to cause nonuniformity in the first place as compared with the oblique bookshelf structure in the prior application. It is considered that the stripe texture is hardly generated.

However, when a liquid crystal element is actually manufactured, a stripe texture may be naturally observed depending on the type of liquid crystal material. Therefore, for such a liquid crystal element, as an external electric field, Ps · Erms> 15 [(nC / cm ² ) · V / u
m)], it was found that the stripe texture disappeared when an external voltage of at least 1 second was applied. This is presumably because the layer structure that was once disturbed in the temperature decreasing process was restored again by applying an external voltage, and a uniform layer structure was obtained.

The external voltage application processing (strong electric field processing) is performed, for example, in a liquid crystal device using the liquid crystal element, during a startup period from immediately after the power is turned on until an image is actually displayed, or a fixed time after the power is turned on. Stable element characteristics can be obtained by appropriately setting the drive waveform to be performed during a so-called screen saver period after a lapse of time or both.

If the external light source is turned on during this external voltage application processing, the image being processed (for example, an image in which the entire screen is displayed in white) is forcibly displayed, and the user is inconvenienced. Because there is a risk of pleasure,
Preferably, the external light source is substantially turned off during the processing period.

That is, for example, even if a uniform layer structure is obtained, the temperature cycle between high and low temperatures is repeated.
There is a possibility that the layer structure is disturbed due to the change in the layer interval as described above and a striped texture is generated. Even after receiving the history, it can be restored to a uniform layer structure again.

At this time, when the pretilt angle was as low as less than 4 °, such a restoring effect could not be obtained even by an external electric field. In other words, it is considered important to make a configuration in which unevenness of the layer structure is unlikely to occur in the first place.

Thus, for a cell having a pretilt angle of 4 ° or more in anti-parallel, Ps · Ems> 15
By applying an external voltage of [(nC / cm ² ) · (V / um)] for at least a predetermined time (1 second), alignment defects can be eliminated. It has switching characteristics without generation without generation and can achieve both high contrast ratio. Note that such an external voltage application process is performed under the control of a control device provided in the liquid crystal device.

Next, examples of this embodiment and comparative examples will be described.

First, a comparative example will be described.

(Preparation of Liquid Crystal Composition) A liquid crystal composition LC-1 was prepared by mixing the following liquid crystal compounds. The numerical values described in the structural formula are weight ratios at the time of mixing.

[0105]

Embedded image

Physical parameters of the liquid crystal composition LC-1
Is shown below. Phase transition temperature (° C.): ISO (86.3) Ch (6
1.2) SmC * (− 7.2) Cry spontaneous polarization (30 ° C.): Ps = 2.9 nC / cm²  Cone angle (30 ° C.): Θ = 23.3 ° (1000 Hz,
± 12.5 V, Cellgap = 1.4 μm) δ (30 ° C.): 21.6 ° Spiral pitch in SmC * phase (30 ° C.): 20 μm or more

(Preparation of Liquid Crystal Cell) 700
A pair of glass substrates having a thickness of 1.1 mm on which the ITO film was formed was prepared. Then, a commercially available TFT alignment film SE7992 (manufactured by Nissan Chemical Industries, Ltd.) is applied on the transparent electrode of this substrate by a spin coating method, followed by pre-drying at 80 ° C. for 5 minutes, and then heating at 200 ° C. for 1 hour. Firing,
A polyimide film having a thickness of 50 ° was formed.

Next, the polyimide film on the substrate was subjected to a rubbing treatment with a nylon cloth as a uniaxial orientation treatment. Here, the rubbing treatment conditions are as follows:
Using a rubbing roll in which nylon (NF-77 / manufactured by Teijin) is bonded to a 0 m roll, the pushing amount is 0.3 m.
m, feed speed 10 cm / sec, rotation speed 1000 rpm
m and the number of times of feeding was 4.

Next, silica beads having an average particle size of 1.5 μm were scattered as spacers on one of the substrates, and the rubbing directions of the substrates were opposed to each other so as to be antiparallel to each other. A cell with a gap (an empty cell A of a single pixel) was formed.

(Preparation of Cell for Evaluation of Pretilt Angle) A substrate prepared under the same conditions as the above empty cell was prepared, and an average particle size of 9 was prepared.
μm silica beads were scattered, and the rubbing directions of the substrates were opposed to each other so as to be antiparallel (anti-parallel) to form cells with uniform cell gaps (empty cells of a single pixel). The above LC-1 was injected into this empty cell,
The temperature was raised to (Ch phase), and the pretilt angle was measured by the crystal rotation method described above. As a result, the pretilt angle was 2.0 °.

The liquid crystal composition LC-1 was injected into the empty cell A of the single pixel produced by the above process at the temperature of the Ch phase, and the liquid crystal was cooled to a temperature showing a chiral smectic liquid crystal phase. , Before and after the Ch-SmC * phase transition, a cooling process was performed by applying an offset voltage (DC voltage) of -5 V to produce Sample A. For the sample A, the following items were evaluated.

1. Orientation State The orientation state of the liquid crystal of Sample A was observed with a polarizing microscope. As a result, it was found that at room temperature (30 ° C.), a striped texture was formed on the entire surface of the cell in the state where no voltage was applied. The angle formed between the average longitudinal direction of the stripe texture and the direction of the uniaxial orientation treatment was about 3 °. In addition, a more detailed observation of each stripe texture revealed that the darkest axis was slightly different in each stripe region, and the darkest axis distribution had a width of about 4 °. I understood that. The layer normal direction was uniform in one direction over the entire surface of the cell.

[0113] 2. Optical response by rectangular wave application For sample A, the cell was placed in a polarizing microscope equipped with a photomultiplier under crossed Nicols such that the polarization axis was in a dark field with no voltage applied, and 60 Hz (± 5 V).
And the optical level was measured while changing the voltage by applying the rectangular wave voltage.

As a result, when a voltage having a positive polarity is applied, a plurality of micro regions in which molecules are inverted to a white state appear. Thereafter, when the applied voltage is gradually increased, the area of these micro regions gradually increases. It was observed that it increased. Further, it was confirmed that the optical response did not depend on the previous state and a stable halftone state was obtained.

Further, about a negative voltage, an optical response of about 1/10 was observed when a positive voltage having the same absolute value was applied, and the average value of the optical response for the positive and negative voltages was the same as the previous state. It was confirmed that a stable halftone could be obtained without depending on.

Further, at 10 to 50 ° C., a square wave ± 5
As a result of measuring the contrast when V was applied, the lowest value was 90 at 10 ° C.

S. Changes due to strong electric field treatment Maximum ± 18 V at 30 ° C for sample A, 1H
A triangular wave of z was applied for 10 seconds. The external electric field at this time is Ps · Erms = 17.4 [(nC / cm ² ) · (V /
um)]. As a result, no particular change in the orientation was observed as compared to before the voltage application.

Next, examples will be described.

(Preparation of Liquid Crystal Cell) 700
A pair of glass substrates having a thickness of 1.1 mm on which the ITO film was formed was prepared. Then, a commercially available TFT alignment film JALS2022 (manufactured by Nippon Synthetic Rubber Co., Ltd.) is applied on the transparent electrode of this substrate by a spin coating method.
After pre-drying for 200 minutes, the film was heated and baked at 200 ° C. for 1 hour to form a polyimide film having a thickness of 150 °.

Next, the polyimide film on the substrate was subjected to a rubbing treatment with a nylon cloth as a uniaxial orientation treatment. Here, the rubbing treatment conditions are as follows:
Using a rubbing roll with nylon (NF-77 / manufactured by Teijin) bonded to a 0 cm roll, the pushing amount is 0.3 m
m, feed speed 10 cm / sec, rotation speed 1000 rpm
m and the number of times of feeding was 4.

Next, silica beads having an average particle size of 1.5 μm were scattered as spacers on one of the substrates, and the rubbing directions of the substrates were opposed to each other so as to be antiparallel to each other. A cell with a cell gap (empty cell B of a single pixel) was obtained.

(Preparation of Cell for Evaluation of Pretilt Angle) A substrate prepared under the same conditions as the above empty cell was prepared, and an average particle diameter of 9 was prepared.
μm silica beads were scattered, and the substrates were rubbed so that the rubbing directions of the substrates were antiparallel to each other (anti-parallel) to obtain cells having a uniform cell gap (empty cells of a single pixel).

Next, the LC-1 was injected into the empty cell, the temperature was raised to 62 ° C. (Ch phase), and the pretilt angle was measured by the crystal rotation method. As a result, the pretilt angle was 7.0 °.

Further, the liquid crystal composition LC-1 is injected into the empty cell B of the single pixel produced by the above process at the temperature of the Ch phase, and the liquid crystal is cooled to a temperature showing a chiral smectic liquid crystal phase. Before and after the Ch-SmC * phase transition, a cooling process was performed by applying an offset voltage (DC voltage) of -5 V to produce a sample B of a liquid crystal element. For the sample B, the following items were evaluated.

[0125] 1. Alignment State The polarization state of the liquid crystal of Sample B was observed under a polarizing microscope. As a result, at room temperature (30 ° C.), no voltage was applied, and over an area of about 50% of the entire cell area,
It was found that a striped texture similar to that of the comparative example was formed. The angle formed between the average longitudinal direction of the stripe texture and the direction of the uniaxial orientation treatment was about 3 °.

Further, when a more detailed observation was performed on each stripe texture, the darkest axis was slightly different in each stripe region.
It was found that the distribution of the darkest axis exists with a width of about 4 °. The layer normal direction was uniform in one direction over the entire surface of the cell.

[0127] 2. Optical response by rectangular wave application For sample B, the cell was placed in a polarizing microscope equipped with a photomultiplier under crossed Nicols such that the polarization axis was in a dark field with no voltage applied, and 60 Hz (± 5 V).
And the optical level was measured while changing the voltage by applying the rectangular wave voltage.

As a result, as a switching state of the stripe texture portion, when a positive voltage is applied, a plurality of minute regions in which molecules are inverted to a white state appear, and thereafter the applied voltage is gradually increased. It was observed that the area of these micro regions gradually increased.

Further, it has been confirmed that the optical response does not depend on the previous state and a stable halftone state can be obtained. In addition, an optical response of about 1/10 of the case of applying a positive voltage having the same voltage absolute value to a negative voltage was confirmed,
It has been confirmed that the average value of the optical response to the positive and negative voltages does not depend on the previous state and a stable halftone can be obtained.

On the other hand, the orientation state of the other portions where the stripe texture is not generated is extremely uniform, and the switching state is so-called domainless switching without the appearance of minute regions as described above. It could be confirmed.

Further, the negative voltage is 1/10 of the case of applying the positive voltage having the same absolute value of the voltage as described above.
It was confirmed that the average value of the optical response to the positive and negative voltages did not depend on the previous state, and that a stable halftone was obtained.

As a result of measuring the contrast when a rectangular wave ± 5 V was applied at 10 to 50 ° C., the lowest value was 1
120 at 0 ° C. was a good result as compared with Comparative Example (90).

3. Change due to strong electric field treatment.
Hz triangular wave was applied for 10 seconds. The external electric field at this time is Ps · Ems = 17.4 [(nC / cm ² ) · (V /
um)].

As a result, the stripe texture generated immediately after the temperature dropped completely disappeared, and the whole surface was extremely uniform and the switching state was changed to a so-called domainless switching without the appearance of minute regions. The situation was confirmed.

In this orientation state, 10 to 50
As a result of measuring the contrast when a rectangular wave of ± 5 V was applied at ° C, the lowest value was 200 at 10 ° C, which was a better result than before (120) the electric field was applied.

In addition, regarding this electric field application treatment, a maximum of ± 12 V and 1 Hz triangular wave at 30 ° C. (the external electric field at this time is Ps · Erms = 11.6 [(nC / cm ² ) ·
V / um)]. ) Was applied for 10 seconds, no particular change in orientation was observed, and the characteristics were the same as before the voltage application treatment.

Regarding the applied waveform, the triangular wave and the sine wave, which are waveforms in which the external voltage waveform changes with time, had the same effect. Required voltage value was slightly higher.

[0138] 4. Changes due to temperature history ± 18 V at 30 ° C. for sample B, 1
Hz element for 10 seconds
A heat cycle from + 60 ° C to -5 ° C was performed 5 times.
As a result, as before the voltage application process, the room temperature (30
° C), 50% of the entire cell area without voltage application
A stripe-shaped texture similar to that of the comparative example was formed over a small area, and the effect of the voltage application process disappeared.

Next, a triangular wave of 1 Hz at a maximum of ± 18 V was again applied to the liquid crystal element at 30 ° C. for 10 seconds. As a result, it was confirmed that the stripe texture completely disappeared again, and the entire surface was extremely uniform as described above, and the state of switching was changed to a so-called domain-less switching without the appearance of minute regions.

As described above, it is effective that the voltage application processing according to the present embodiment is performed periodically, and that the use in combination with the driving waveform is effective for the temperature history.

[0141]

As described above in detail, according to the present invention, a pair of substrates arranged opposite to each other so that the directions of the uniaxial orientation treatment are parallel and opposite to each other, exhibit a chiral smectic phase and at least one of them. The liquid crystal device having a liquid crystal having a pretilt angle of 4 ° or more of the substrate and a polarizing plate provided on at least one of the substrates has a spontaneous polarization value (Ps) of the liquid crystal and an effective value applied to the liquid crystal. The product Ps · Erms with the value electric field (Erms) is: Ps · Erms> 15 [(nC / cm ² ) · (V / u
m)], a liquid crystal device provided with a liquid crystal element having uniform switching characteristics and high contrast can be provided by applying the external voltage for a predetermined time or longer.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a structure of a liquid crystal device including a liquid crystal element according to an embodiment of the present invention.

FIG. 2 is a diagram schematically showing a configuration of one substrate of the liquid crystal element.

FIG. 3 is a diagram showing a cross-sectional structure of a pixel portion of the one substrate.

FIG. 4 is an equivalent circuit diagram of the pixel portion.

FIG. 5 is a diagram showing drive signals and optical characteristics applied to the pixel portion.

[Explanation of symbols]

 Reference Signs List 20 active matrix substrate 40 counter substrate 43a, 43b alignment film 49 liquid crystal layer 70 liquid crystal device 80 liquid crystal element 81a, 81b substrate 85 liquid crystal 87a, 87b polarizing plate 82a, 82b electrode 84a, 84b alignment control film 94 TFT 95 pixel electrode

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G09G 3/34 G09G 3/36 3/36 G02F 1/137 510 F-term (Reference) 2H088 EA02 FA10 GA03 GA04 HA06 HA08 HA18 JA16 KA02 KA07 KA14 KA21 KA28 LA07 MA02 MA11 2H090 HB08Y JB13 KA13 LA04 LA09 MA02 MA07 MA10 MB01 2H093 NA15 NA16 NA21 NA53 NB01 NC34 NC49 NC59 ND04 ND06 ND32 NE06 NF16 NH02 NH12 NH18 AF12 BC12 FA18 BC12 A FA25 GA02 5C080 AA10 BB05 CC10 DD05 DD08 DD30 EE28 FF07 JJ02 JJ03 JJ04 JJ06

Claims (12)

[Claims] 1. A pair of substrates having an electrode for applying a voltage to the liquid crystal while holding a liquid crystal exhibiting a chiral smectic phase and having been subjected to a uniaxial alignment treatment for aligning the liquid crystal, and at least one of the substrates. A liquid crystal device comprising a liquid crystal element having a polarizing plate provided on a substrate side, wherein a pair of substrates of the liquid crystal element are opposed to each other such that the directions of the uniaxial alignment treatment are parallel and opposite. The liquid crystal has a pretilt angle of at least one substrate of 4 ° or more, and the liquid crystal element has a spontaneous polarization value (Ps) of the liquid crystal and an effective electric field (Erm) applied to the liquid crystal.
s) and the product Ps · Erms is Ps · Erms> 15 [(nC / cm ² ) · (V / u
m)], wherein the external voltage is applied for a predetermined time or more. 2. The phase transition series of the liquid crystal from the high temperature side isotropic liquid phase (ISO.)-Cholesteric phase (Ch) -chiral smectic C phase or isotropic liquid phase (IS
O. 2. The liquid crystal device according to claim 1, wherein the liquid crystal device is a chiral smectic C phase. 3. The liquid crystal device according to claim 1, wherein, when the external voltage is applied, the applied external voltage has a waveform that changes with time. 4. The method according to claim 1, wherein the application of the external voltage is performed during a start-up period from immediately after power-on until an image is displayed.
A liquid crystal device according to the item. 5. The method according to claim 1, wherein the application of the external voltage is performed during a screen saver period.
The liquid crystal device according to any one of claims 1 to 4. 6. The method according to claim 1, wherein the application of the external voltage is performed periodically at a predetermined timing.
6. The liquid crystal device according to claim 1. 7. The liquid crystal device according to claim 1, wherein the external light source is substantially turned off while the external voltage is being applied. 8. The liquid crystal shows a first state in which, when no voltage is applied, the average molecular axis of the liquid crystal is monostable, and when a voltage of the first polarity is applied, the average molecular axis of the liquid crystal becomes an applied voltage. Tilted to one side from the mono-stabilized position at an angle corresponding to the magnitude of the liquid crystal, and when a voltage of a second polarity having a polarity opposite to the first polarity is applied, the average molecular axis of the liquid crystal is changed to the single molecular. While tilting to the opposite side from when the first polarity voltage is applied from the stabilized position, the average molecular axis of the liquid crystal when the first polarity voltage is applied and the second polarity voltage is applied. 2. The method according to claim 1, wherein β1> β2 when the tilt angles of the maximum tilt state with respect to the mono-stabilized position in the first state are β1 and β2, respectively. Liquid crystal devices. 9. The tilt angles β1 and β2 satisfy β1 ≧ β.
9. The liquid crystal device according to claim 8, wherein the value is 5 × β2. 10. The liquid crystal device according to claim 1, further comprising: a driving circuit for driving the liquid crystal element; and a backlight light source.
A liquid crystal device according to the item. 11. The liquid crystal device according to claim 1, further comprising: a driving circuit for driving the liquid crystal element; and a reflector.
A liquid crystal device according to the item. 12. The driving circuit according to claim 10, wherein the driving circuit includes an active element that is provided on the substrate and performs active matrix driving.
The liquid crystal device according to the above.