JP2003255398A - Liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that if a liquid crystal material having lower viscosity is used to obtain high speed response, reliability is hardly secured, and if cell gap is narrowed, a liquid crystal modulation ratio (a panel transmittance) is lowered. <P>SOLUTION: A liquid crystal panel comprising a liquid crystal having 10% cyano-based material content, containing a terphenyl group and having refractive index anisotropy Δn of 0.28 and 51 mPa.s viscosity or a liquid crystal having 10% cyano-based material content, containing a PCH (Phenyl cyclohexyl) group and having refractive index anisotropy Δn of 0.27 and 45 mPa.s viscosity has 2 msec response time and 70% liquid crystal modulation ratio when the panel has 2.6 μm cell gap. 2 msec response time and 70% liquid crystal modulation ratio (when the panel has 2.6 μm cell gap) or 2.2 msec response time and 80% liquid crystal modulation ratio (when the panel has 3 μm cell gap) are in a practical range of a specification to secure reliability in any of the cyano-based liquid crystal having 10% cyano-based material content, a fluoro-based or a fluorotolan-based liquid crystal. A black color insertion ratio of ≤10% in 180 Hz driving is required for the PCH-cyano-based material and ≥15% black color insertion ratio is required for other materials. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device used in a portable television, a portable information terminal, etc., and more particularly to a field sequential color liquid crystal display device suitable for displaying moving images.

[0002]

2. Description of the Related Art A field-sequential color type liquid crystal display device is a type in which an image of three colors is sequentially displayed in one pixel without providing a color filter in each pixel, which is higher than that of a conventional driving type liquid crystal. It has advantages such as high transmittance and high resolution.

In Japanese Patent Laid-Open No. 11-14988, an OC
A field sequential color display type liquid crystal display using a B-mode liquid crystal panel is disclosed.

FIG. 4 is a conceptual diagram of a liquid crystal panel used in the field sequential color liquid crystal display disclosed in Japanese Patent Laid-Open No. 11-14988.

A phase compensation plate 403 is arranged in front of a bend alignment liquid crystal cell 401 having a cell gap of 7 μm or less, and a display panel 410 constituted by sandwiching the cell and the phase compensation plate with a crossed polarizer 405, and the display panel. This is a liquid crystal display provided with a TFT active matrix that drives each pixel by partitioning it into pixels arranged in a matrix, and a surface light source 407 that sequentially irradiates three colors of R, G, and B on the back surface of a display panel.

That is, since a color image is displayed by mixing RGB colors over time, color filter layers for three RGB colors are not required. Therefore, when trying to obtain the same resolution with the same size, the area of one pixel is tripled, and a bright panel can be obtained. On the contrary, when the pixel size is the same, the resolution can be increased three times.

However, when there is a rapidly moving scene or when the human line of sight moves rapidly (saccade), the residual color misregistration of the R, G, B signals on the retina is perceived as colored. This causes the problem of color breakage. As measures against this color break, for example, Japanese Patent Laid-Open No. 9-9
As disclosed in Japanese Patent Publication No. 0916, various methods have been proposed in which the driving method is devised. That is, R
In addition to the three primary colors of GB, the display device is configured so that a color image can be displayed by forming one frame by a frame sequential method using at least one or more intermediate color fields. One frame is R, G, B3. It is formed by fields of primary colors and intermediate colors thereof, for example, white or intermediate fields of three primary colors.

With such a configuration, the display time of each field is shortened, and the portion to which the color signal of the previous field generated due to the time shift is added is displayed whitish. Further, the color signals B and R that are slightly added to the front and rear are very inconspicuous colors. Therefore, it is possible to display with almost no color breakup.

As another method, R in one frame
There is also proposed a method of eliminating color breakup by high speed driving such as 6 × speed driving for displaying color images in the order of GBRGB.

[0010]

However, in the case of the field sequential color type liquid crystal display device as described above, the following problems remain. (1) W (white) insertion drive (RGBW) to prevent color breakup
Drive), RGB drive by W (normal drive)
It requires a liquid crystal panel that responds faster than the above. Also, R
In order to drive at a high speed such as 6x GBGB drive, a liquid crystal panel having a higher response is required. However, if the liquid crystal material is made to have a low viscosity for high-speed response, it is difficult to secure reliability. Further, if the cell gap is reduced, the modulation rate of the liquid crystal, that is, the transmittance of the panel is reduced.

(2) OCB as a high-speed response liquid crystal panel
When the mode is applied, a reverse transition state occurs in which the liquid crystal orientation changes from the bend state to the splay state. Therefore, the black voltage (that is, in the case of normally white display, a voltage of 5 to 6 V is applied for black display) is set to 1
It is necessary to insert black at a rate of some percentage of the frame (hereinafter, this insertion rate is referred to as "black insertion rate"). In order to prevent the transition to the reverse transition state, it is necessary to increase the black insertion rate, but the time during which the liquid crystal is in the on state (hereinafter referred to as the "time aperture ratio") is substantially small. Therefore, the transmittance is substantially reduced and the efficiency is reduced.

[0012]

In order to solve the above problems, the field sequential color liquid crystal display device of the present invention has the following constitution. That is, (1) a liquid crystal panel, a light source for irradiating the liquid crystal panel, and a driving means for switching the color of the light source in time sequential order and controlling the transmission or reflection state of the liquid crystal panel in synchronization therewith,
In a liquid crystal display device that performs color display by temporally additive color mixing, the liquid crystal panel is an OCB mode liquid crystal in which a phase compensating plate is arranged in front of bend alignment liquid crystal, and a phase difference Δn · d (retardation) of the liquid crystal layer. Is 600 nm or more 900
and the liquid crystal layer is made of a cyano material.

(2) The cyano material content is set to 10% or less.

(3) The cyano material is PCH (phenyl
It was configured to contain a cyclohexane group.

(4) The cyano material is a cyano material containing a terphenyl group.

(5) The thickness of the liquid crystal layer is 2.5 μm or more.3.
The configuration is 5 μm or less.

(6) The refractive index anisotropy Δn of the liquid crystal layer is 0.2.
The configuration is 4 or more.

(7) The viscosity coefficient η of the liquid crystal layer is 30 mPa ·
The configuration was s or more and 60 mPa · s or less.

(8) A liquid crystal panel, a light source for irradiating the liquid crystal panel, and a driving means for time-sequentially switching the color of the light source and controlling the transmission or reflection state of the liquid crystal panel in synchronism therewith, are added temporally. In a liquid crystal display device that performs color display with mixed colors, the liquid crystal panel is an OCB mode liquid crystal in which a phase compensation plate is provided in front of bend-aligned liquid crystal,
A black voltage for applying a voltage for black display was inserted and driven at a constant rate in one frame, and the liquid crystal layer was a cyano-based material containing a PCH (phenyl cyclohexane) group.

The driving frequency in (9) and (8) is 300.
The frequency is set to Hz or less.

(10) A liquid crystal panel, a light source for irradiating the liquid crystal panel, and a driving means for time-sequentially switching the color of the light source and controlling the transmission state or the reflection state of the liquid crystal panel in synchronization therewith, and the temporal addition In a liquid crystal display device that performs color display with mixed colors, the liquid crystal panel is an OCB mode liquid crystal in which a phase compensation plate is provided in front of bend alignment liquid crystal, and a black voltage for applying a voltage for black display is in one frame. The liquid crystal layer was made of a cyano-based material containing a terphenyl group and was inserted at a constant rate into the liquid crystal layer and driven at a driving frequency of 360 Hz or higher.

(11) A liquid crystal panel, a light source for irradiating the liquid crystal panel, and a driving means for time-sequentially switching the colors of the light source and controlling the transmission or reflection state of the liquid crystal panel in synchronization with the liquid crystal panel are provided. In a liquid crystal display device that performs color display with mixed colors, the liquid crystal panel is an OCB mode liquid crystal in which a phase compensation plate is provided in front of bend alignment liquid crystal, and a black voltage for applying a voltage for black display is in one frame. The liquid crystal layer was made of a fluoro-based material or a fluoro-tolan-based material and was driven at a driving frequency of 360 Hz or higher.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) A first embodiment of the present invention will be described with reference to the drawings.

FIG. 1A is an enlarged sectional view showing the structure of the liquid crystal display device according to the first embodiment of the present invention. Figure 1
FIG. 2B is an enlarged plan view of a pixel portion showing the configuration of the liquid crystal display device according to the first embodiment of the present invention.

In FIG. 1, 1 is a liquid crystal panel, 2 is a backlight, 3 is an array substrate, 4 is a counter substrate, 5 is a liquid crystal layer, 6 is a counter electrode, 7 is a pixel electrode, and 8 is connected to a pixel electrode 7. A video signal line for supplying a video signal, 9 is a scanning signal line,
10 is a semiconductor switch element, 11 is a first insulating layer, 12 is a second insulating layer, 13 is a black matrix layer, 14a is an alignment film formed on the inner surface of the array substrate 3, and 14b is an alignment film formed on the inner surface of the counter substrate 4. Membrane, 15 is LED light source, 15
a is a red LED, 15b is a green LED, and 15c is a blue L
ED, 16 are reflection plates, and 17 is a light guide plate.

The first embodiment is a field-sequential color drive type liquid crystal display device of OCB mode liquid crystal in which a phase compensating plate is arranged in front of bend alignment liquid crystal.
The operation will be described below with reference to FIG.

First, a conductor made of Al, Ti or the like is formed on the array substrate 3 and the scanning signal line 9 is patterned into a predetermined shape. After forming the first insulating layer 11 on the thus formed first electrode group, an a-Si layer and an n + type a-Si layer (both are not shown in the figure) are formed on a predetermined portion of the first insulating layer 11. And the semiconductor switch element 10 is formed. Furthermore, the first insulating layer 11 and the semiconductor switch element 1
A conductor made of Al, Ti, or the like is formed on a predetermined portion of 0, and a second electrode group including the video signal line 8 is patterned into a predetermined shape.

Next, the second insulating layer 12 made of SiNx or the like is formed on the array substrate 3 on which the second electrode group is formed. The second insulating layer 12 also serves as a protective film that protects the semiconductor switch element 10.

Further, the pixel electrode 7 is made of a transparent conductor I.
It is formed of a TO film.

After that, alignment films 14a and 14b made of polyimide or the like are formed on the array substrate 3 and the counter substrate 4 in order to align the arrangement of the molecules of the liquid crystal layer 5.

In the OCB mode liquid crystal display element as in the invention of the present application, the array substrate 3 and the counter substrate 4 are rubbed, but the directions are parallel to each other so that they are parallel.

The counter substrate 4 is provided so as to face the array substrate 3, and the counter electrode 6 and the black matrix layer 13 are formed in a predetermined pattern.

The array substrate 3 and the counter substrate 4 thus produced each have an initial orientation in a predetermined direction, and the peripheral portions thereof are bonded with a sealant, and then the liquid crystal layer 5 is injected and sealed. .

The semiconductor switch element 10 is turned on by a drive signal inputted from the video signal line 8 and the scanning signal line 9,
Controlled off. Then, an electric field is generated by the voltage applied between the pixel electrode 7 connected to the semiconductor switch element 10 and the counter electrode 6, and the orientation of the liquid crystal layer 5 is changed to control the brightness of each pixel. Is displayed.

In the liquid crystal display device of the present application, the liquid crystal molecules are in a splay alignment state in which the liquid crystal molecules are aligned substantially in parallel when no voltage is applied in the initial stage, and the alignment of the liquid crystal is transferred to the bend alignment state used for display. In order to carry out this transition, a relatively large transition voltage, for example, about 25 V was applied to the liquid crystal layer.

The OCB mode liquid crystal display device has a substrate and a liquid crystal, and displays by applying a voltage to the liquid crystal, and a zero voltage alignment state when no voltage is applied to the liquid crystal and a display alignment state used in the display state. However, it is a kind of liquid crystal display device that makes a transition from a zero voltage alignment state to a display alignment state by applying a transition voltage, and can realize a display with a high-speed response and a wide viewing angle.

Since the first embodiment is a field-sequential color liquid crystal display device, a color filter which is indispensable for a normal active matrix color liquid crystal display device is not necessary. Instead, the backlight 2 needs LED light sources 15a, 15b, and 15c capable of emitting red (R), green (G), and blue (B) colors. The light emitted from the LED light source 15 is reflected by the reflection plate 16 and is incident on the liquid crystal panel 1 while being repeatedly reflected by the light guide plate 17. In this manner, the LED light sources 15a, 15b, and 15c of RGB colors for irradiating the liquid crystal panel 1 are sequentially switched in time, and the light transmission state of the liquid crystal panel 1 is controlled in synchronism therewith, so that color is added in a temporally additive color mixture. Display.

With the above structure, the transmittance of the panel is remarkably improved as compared with the conventional method using a color filter, so that not only a bright liquid crystal panel can be obtained, but also an LED of high color purity is used as the light source 15. By using, N
It is possible to realize a much higher color reproducibility than the conventional method in which the TSC ratio is 100% or more.

Next, the operation and effect of the panel structure according to the first embodiment will be described.

Since the first embodiment is a field-sequential color liquid crystal display device, it is possible to display a color image without using a color filter by mixing RGB colors over time. Therefore, if the timing of driving the video signal does not follow the timing of emitting each color of RGB, the colors are not mixed properly, and an image accompanied by color misregistration is displayed or flicker occurs. In order to display each color of RGB in one frame, that is, in 16.6 msec, it is necessary to switch each color in about 5.6 msec. Further, if it is attempted to secure writing time to pixels, backlight lighting time, and the like, The liquid crystal response time τr + d (total rise time and fall time) is 3 msec.
The following is preferable.

As a method for solving this problem, JP-A-11-14988 proposes to use OCB mode liquid crystal in the liquid crystal panel. The OCB mode liquid crystal is certainly capable of high-speed response as compared with other liquid crystal modes such as TN, but even if it is intended to realize a high-speed response of 3 msec or less, the cell gap is narrowed to 2 μm or less, or It is necessary to take measures such as reducing the viscosity of the liquid crystal material.

However, in terms of practical use, it is necessary to secure not only high-speed response but also the transmittance of the panel as much as possible and reliability at the same time. we,
The conditions of the OCB liquid crystal panel structure for achieving both high-speed response, high transmittance, and reliability were examined.

First, in order to achieve both high-speed response and high transmittance, a cyano containing a PCH (phenyl cyclohexane) group capable of increasing the birefringence anisotropy Δn to 0.2 or more. The viscosity of liquid crystal materials, which are roughly classified into four types, that is, cyano type, fluor type, and fluoro tolan type containing a terphenyl group, was reduced. In addition, in order to determine only the dependency of the liquid crystal material on the transmittance, the transmittance of the light which is modulated by the liquid crystal is excluded by excluding the influence of the transmittance of the polarizing plate or the color filter (hereinafter, the liquid crystal modulation rate. I said).

In the cyano material, when the cyano content is 18%, the birefringence anisotropy Δn = 0.28 and the viscosity η
= 44 mPa · s, and the cell gap 2.
Response time τr + d = 1.5msec on 6μm panel,
A liquid crystal modulation rate of 85% was obtained. However, 60 ℃, 90%
In high temperature and high humidity test, the voltage holding ratio was 50% compared to the initial value.
After 0 hours, a decrease of 10% or more is seen, and there is a problem in reliability, so it is not suitable for practical use.

A birefringent anisotropy Δ of a liquid crystal containing a terphenyl group was used as a material whose cyano content was suppressed to 10%.
n = 0.28, viscosity η = 51 mPa · s, liquid crystal containing PCH group, birefringence anisotropy Δn = 0.27, viscosity η =
A physical property value of 45 mPa · s was obtained, and the cell gap was 2.6.
With a panel of μm, a response time τr + d = 2 msec and a liquid crystal modulation rate of 70% were obtained. Although the performance is slightly inferior to the material with a cyano content of 18%, no decrease in the voltage holding ratio is seen even after 500 hours in the high temperature and high humidity test at 60 ° C and 90%, and the reliability is high. It turned out that there was no problem in terms of. Further, even with a cyano content of 10%, 60 ° C. and 90 ° C. were obtained for each material with viscosity η = 37 mPa · s, viscosity η = 34 mPa · s, and viscosity η = 29 mPa · s.
In high temperature and high humidity test, the voltage holding ratio is 5% compared to the initial value.
After the lapse of 00 hours, a decrease of 10% or more was observed. This is due to the viscosity reducing material contained to reduce the viscosity, which means that reliability and high-speed response are in a trade-off relationship.

In the case of a fluoro material, physical properties such as birefringence anisotropy Δn = 0.25 and viscosity η = 49 mPa · s were obtained, and the response time τ was obtained in a panel with a cell gap of 2.6 μm.
r + d = 2 msec and a liquid crystal modulation rate of 70% were obtained. Although the performance is slightly inferior to the material with a cyano content of 18%, it is 5 in the high temperature and high humidity test at 60 ° C and 90%.
It was found that the voltage holding ratio did not decrease even after the lapse of 00 hours, and there was no problem in terms of reliability.

In the fluorotolan material, physical properties such as birefringence anisotropy Δn = 0.25 and viscosity η = 43 mPa · s were obtained, and a response time τr + d = 2 msec was obtained in a panel with a cell gap of 2.6 μm. A modulation rate of 70% was obtained. Although the performance is slightly inferior to the material with a cyano content of 18%, no decrease in the voltage holding ratio is seen even after 500 hours in the high temperature and high humidity test at 60 ° C and 90%, and the reliability is high. It turned out that there was no problem in terms of.

FIG. 2 summarizes the above experimental results. FIG. 2 is a graph in which the horizontal axis represents the response time and the vertical axis represents the liquid crystal modulation rate, and the performance of the sample of the simple cell using each liquid crystal material is plotted. In FIG. 2, ◯, ⊚, and ● indicate that the reliability was good, and x indicates that there was a problem in the reliability. ○ is fluoro type, ◎ is fluoro tolan type, ●
Shows the result of a cyano-based (cyano content 10%) sample.

From the above results, in any of the cyano-based materials having a cyano content of 10%, the fluoro-based materials, and the fluorotoran-based materials, in order to ensure reliability, the specifications of the area surrounded by the broken line, that is, Response time τr + d
= 2 msec, liquid crystal modulation rate 70% specification (cell gap 2.6 μm), or response time τr + d = 2.2
It was clarified that the range of specifications (cell gap 3 μm) with msec and liquid crystal modulation rate of 80% was the practical range.

Further, in the OCB mode liquid crystal panel, there is a problem that a reverse transition state occurs in which the liquid crystal alignment changes from a bend state for displaying an image normally to a splay state. Therefore, a method has been proposed in which a black voltage (that is, in the case of normally white display, a voltage of 5 to 6 V is applied for black display) is inserted at a rate of some percentage in one frame ( Hereinafter, this insertion rate will be referred to as "black insertion rate". In order to prevent the transition to the reverse transition state, it is necessary to increase the black insertion rate, but the time for which the liquid crystal is in the on state (hereinafter referred to as “time aperture ratio”) is substantially small. Therefore, the transmittance is substantially reduced and the efficiency is reduced.

Therefore, in order to maximize the utilization efficiency of the light source when implementing the field sequential color system with the OCB mode liquid crystal, in addition to the liquid crystal modulation rate, the time aperture rate including the response time and the black insertion rate is added. You must judge by total efficiency.

Therefore, the condition of the minimum black insertion rate required was clarified. As a result, the black insertion rate depends on the type of liquid crystal material,
And it became clear that it depends on the driving frequency. It is also known that the black insertion rate differs depending on the operating temperature, and that the higher the temperature, the higher the black insertion rate is required.
Therefore, for practical purposes, the minimum black insertion rate should be determined in anticipation of use at high temperatures.

FIG. 3 shows the results of obtaining the minimum black insertion rate required in a simple cell sample using each liquid crystal material when driven at each frequency at an operating temperature of 80 ° C.

The liquid crystal material used in the experiment was 60 ° C. and 90 ° C.
In the high temperature and high humidity test of%, no decrease in voltage holding ratio was observed even after 500 hours, and it is considered that there is no problem in reliability.

From the results shown in FIG. 3, a peak occurs at 100 Hz to 120 Hz in any material,
After that, the minimum black insertion rate may become smaller as the driving frequency increases.

From this result, it is shown that PCH- when driving at a triple speed of RGB, that is, when driving at 180 Hz.
Cyan-based materials require a black insertion rate of 10% or less, but PC
A black insertion rate of 15% or more is required for materials other than H-cyano materials. In addition, in order to prevent color breakup, it may be necessary to drive at 6 times the speed of RGB, that is, 360 Hz, but any material may have a black insertion rate of 15% or less, so the response time and liquid crystal modulation rate specifications The liquid crystal material may be determined mainly with respect to.

It should be noted that black insertion is not essential for OCB mode liquid crystal of the field sequential color system, and there is also a method of setting and using a white voltage that does not cause reverse transition without black insertion. In that case, it is not necessary to consider the driving frequency dependency of the black insertion rate, and it goes without saying that it is not necessary to select the type of liquid crystal material depending on the driving frequency.

As described above, the liquid crystal material, the cell gap,
By determining the optimal panel configuration for each by the combination of the refractive index anisotropy Δn and the driving method (the range of the numerical values described in the examples), the total light utilization efficiency is high and the reliability is high. An OCB mode liquid crystal of field sequential color system can be obtained.

[0060]

As described above, the liquid crystal display device according to the present invention can achieve the following operational effects. That is, (1) a high-speed response liquid crystal panel is required to prevent color breakup, but a panel with high-speed response, high transmittance, and high reliability can be obtained.

(2) In the driving method for inserting black, the liquid crystal material is selected in consideration of the dependence of the driving frequency, so that the light utilization efficiency can be increased in total.

From the above, suitable for displaying moving images at high speed,
Since it is possible to provide a highly efficient and highly reliable field sequential color liquid crystal display device, its industrial value is extremely large.

[Brief description of drawings]

FIG. 1A is an enlarged cross-sectional view showing a configuration of a liquid crystal display device according to a first embodiment of the present invention, and FIG. 1B is an enlarged plan view of a pixel portion showing a configuration of a liquid crystal display device according to a first embodiment of the present invention. Figure

FIG. 2 is a diagram in which a response time and a liquid crystal modulation rate of a sample of a simple cell using each liquid crystal material are plotted.

FIG. 3 is a diagram showing the drive frequency dependency of the minimum black insertion rate at a use temperature of 80 ° C. in a simple cell sample using each liquid crystal material.

FIG. 4 is a conceptual diagram of a liquid crystal panel used in a conventional field sequential color liquid crystal display.

[Explanation of symbols]

1 LCD panel 2 backlight 3 array substrate 4 Counter substrate 5 Liquid crystal layer 6 Counter electrode 7 pixel electrode 8 video signal lines 9 scanning signal lines 10 Semiconductor switch element 11 First insulating layer 12 Second insulating layer 13 Black matrix layer 14 Alignment film 15 LED light source 15a Red LED 15b green LED 15c blue LED 16 Reflector 17 Light guide plate 401 bend alignment liquid crystal cell 403 Phase compensator 405 Orthogonal polarizer 407 surface light source 410 display panel 411 liquid crystal 412 glass (substrate)

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yasushi Taniguchi             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. F-term (reference) 2H088 GA02 HA03 HA06 HA28 JA09                       LA00 MA06 MA10                 2H091 FA11X FA23Z FA45Z GA06                       GA11 HA09 JA10 KA02 LA15                       LA16                 2H093 NA21 NA65 ND08 ND32 NE04                       NE06

Claims (11)

[Claims] 1. A liquid crystal panel, a light source for irradiating the liquid crystal panel, and driving means for time-sequentially switching the color of the light source and controlling the transmission or reflection state of the liquid crystal panel in synchronization therewith, In the liquid crystal display device that performs color display with various additive colors, the liquid crystal panel is an OCB mode liquid crystal in which a phase compensating plate is arranged in front of bend alignment liquid crystal, and a phase difference Δn · d (retardation) of the liquid crystal layer. Is 60
A liquid crystal display device, which has a thickness of 0 nm or more and 900 nm or less, and wherein the liquid crystal layer is a cyano material. 2. The liquid crystal display device according to claim 1, wherein the content of the cyano material is 10% or less. 3. The cyano material is PCH (phenyl
The liquid crystal display device according to claim 1, further comprising a cyclohexane group. 4. The liquid crystal display device according to claim 1, wherein the cyano-based material is a cyano-based material containing a terphenyl group. 5. The thickness of the liquid crystal layer is 2.5 μm or more.
The liquid crystal display device according to claim 1, wherein the liquid crystal display device has a thickness of 5 μm or less. 6. The refractive index anisotropy Δn of the liquid crystal layer is 0.2.
The liquid crystal display device according to claim 1, wherein the liquid crystal display device has four or more. 7. The liquid crystal layer has a viscosity coefficient η of 30 mPa · s.
The liquid crystal display device according to claim 1, wherein the liquid crystal display device has a thickness of s or more and 60 mPa · s or less. 8. A liquid crystal panel, a light source for irradiating the liquid crystal panel, and driving means for time-sequentially switching the color of the light source and controlling the transmission or reflection state of the liquid crystal panel in synchronization therewith, In a liquid crystal display device that performs color display with such additive color mixture, the liquid crystal panel is an OCB mode liquid crystal in which a phase compensating plate is provided in front of bend alignment liquid crystal, and a black voltage for applying a voltage for black display is A liquid crystal display device, characterized in that the liquid crystal layer is inserted and driven in a fixed ratio in one frame, and the liquid crystal layer is a cyano-based material containing a PCH (phenyl cyclohexane) group. 9. The liquid crystal display device according to claim 8, wherein the drive frequency is 300 Hz or less. 10. A liquid crystal panel, a light source for irradiating the liquid crystal panel, and driving means for time-sequentially switching the color of the light source and controlling the transmission or reflection state of the liquid crystal panel in synchronization therewith, In a liquid crystal display device that performs color display with such additive color mixture, the liquid crystal panel is an OCB mode liquid crystal in which a phase compensating plate is provided in front of bend alignment liquid crystal, and a black voltage for applying a voltage for black display is A liquid crystal display device, wherein the liquid crystal layer is inserted at a constant rate in one frame and driven at a driving frequency of 360 Hz or higher, and the liquid crystal layer is a cyano-based material containing a terphenyl group. 11. A liquid crystal panel, a light source for irradiating the liquid crystal panel, and driving means for time-sequentially switching the color of the light source and controlling the transmission or reflection state of the liquid crystal panel in synchronization therewith, In a liquid crystal display device that performs color display with such additive color mixture, the liquid crystal panel is an OCB mode liquid crystal in which a phase compensating plate is provided in front of bend alignment liquid crystal, and a black voltage for applying a voltage for black display is A liquid crystal display device characterized in that the liquid crystal layer is inserted at a constant rate in one frame and driven at a driving frequency of 360 Hz or higher, and the liquid crystal layer is made of a fluoro-based material or a fluorotolan-based material.