JP4343419B2 - Liquid crystal device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention generally relates to a liquid crystal device that performs color display using liquid crystal .
[0002]
[Prior art]
Conventionally, liquid crystal devices capable of color display have been used in various fields.
(1) A micro color filter arranged on each pixel to enable color display (hereinafter referred to as “micro color filter method”),
(2) Full color display is performed by sequentially irradiating light of different colors and switching light in synchronization with the light irradiation (hereinafter referred to as “field sequential method”),
There is. Among these, the field sequential type liquid crystal device is different from the micro color filter method in which color display is performed by combining a plurality of pixels, and can display color with only one pixel and can increase the definition. The image luminance can be increased by increasing the rate. Further, since it is not necessary to provide a micro color filter for each pixel, the manufacturing yield is improved.
[0003]
Here, a field-sequential liquid crystal device will be briefly described with reference to FIGS.
[0004]
FIG. 8 is a block diagram showing an example of the structure of a conventional liquid crystal device. The liquid crystal device includes a liquid crystal panel P that switches light for each pixel, and drivers 5 and 6 that drive the liquid crystal panel P. And the like, and a backlight device B that sequentially emits light of different colors (red light, green light, and blue light) to the liquid crystal panel P, and a backlight drive unit 7 that drives the backlight device B Has been.
[0005]
When driving this liquid crystal device, as shown in FIG. 9, one frame period F ₀ is divided into _three field periods F ₁ , F ₂ , F ₃ (for example, when the frame frequency is 60 Hz). 1 frame period F ₀ is 16.7 ms, and one field period F ₁ , F ₂ , F ₃ is approximately 5.5 ms), and the backlight device B for each field period F ₁ , F ₂ , F ₃ The liquid crystal panel P is sequentially irradiated with each color light (red light, green light, and blue light) (see FIGS. 9 (a), (b), and (c)), and each field period is synchronized with the light irradiation. By switching the light for each pixel by the liquid crystal panel P for each of F ₁ , F ₂ , and F ₃ (that is, the monochrome image for R, the monochrome image for G, and the monochrome image for B are displayed in order. By different images) Are successively recognized, their images by utilizing the afterimage of the human eye (red image, green image and blue image) and by mixing with visual and is adapted to recognize as a full color image. The display of black and white images in each field period F _1, F _2, F _3, as shown in FIG. 9 (d), is accomplished by line-sequential scanning of each scan line.
[0006]
However, in the case of such a field sequential method, the liquid crystal response needs to be completed in the periods F ₁ , F ₂ , and F _{3 as} short as 1/3 of one frame period. It is necessary to use it. Hereinafter, this point will be described.
[0007]
2. Description of the Related Art Conventionally, as an LCD panel, an active matrix type in which an active element such as a transistor (for example, a thin film transistor such as a TFT) is arranged in each pixel and a nematic liquid crystal has been developed. In this active matrix type liquid crystal panel, a twisted nematic mode is widely used, and the mode is “Applied Physics Letters, Vol. 18, No. 4 (issued on Feb. 15, 1971), page 127. 128, by M. Schadt and W. Helfrich. Recently, an in-plane switching mode using a lateral voltage has been announced, and the viewing angle characteristic, which has been a drawback of the twisted nematic mode, has been improved.
[0008]
In addition, a super twisted nematic mode is used for a liquid crystal panel that is not an active matrix type.
[0009]
By the way, in any of these modes, there is a problem that the response speed of the nematic liquid crystal is as slow as several tens of milliseconds and is not suitable for the field sequential method.
[0010]
On the other hand, a bend alignment cell (π cell) was announced by Bos et al. In 1983 as a liquid crystal panel with improved response speed. In this bend alignment cell, the rubbing directions of both substrates are the same direction, and a bend alignment (see FIG. 3) is realized by applying a voltage higher than a predetermined value to a nematic liquid crystal that is a splay alignment. Is very fast, such as several milliseconds, and is suitable for a field sequential system (Japanese Patent Laid-Open No. 11-14988, OCB cell, Uchida et al.), And the light transmittance (the light reflectance when the cell is a reflection type) is It is controlled by the applied voltage.
[0011]
Note that when the applied voltage is changed, the amount of retardation changes, and the transmittance and reflectance of light change with the change of the amount of retardation. The relationship between the amount of retardation and transmittance T depends on the wavelength of light as λ. Then,
T = sin ² (πR / λ)
The relationship between the retardation amount and the reflectance T is
T = cos ² (π · 2R / λ)
It becomes. Therefore, in order to change the light transmittance from 0% to 100% in the transmissive liquid crystal panel, it is necessary to change the retardation amount to 0 to λ / 2. In the reflective liquid crystal panel, the light reflectance is changed from 0% to In order to change it to 100%, it is necessary to change the retardation amount to 0 to λ / 4. However, the relationship between the retardation amount and the applied voltage is as shown in FIG. 4, for example. In the case of such a characteristic curve, R = 0 cannot be realized because there is no intersection with the horizontal axis. Therefore, by using a phase difference correction plate made of a birefringent medium in a direction orthogonal to the orientation control direction applied to both substrates, the characteristic curve is indicated by the symbol R ₂ so that R ₂ = 0 can be realized. Yes.
[0012]
Uchida et al. Announced the use of a biaxial retardation plate as a retardation member in 1992 from the viewpoint of improving the viewing angle (OCB cell).
[0013]
[Problems to be solved by the invention]
By the way, in the bend alignment cell mentioned above, the relationship between the applied voltage V and the transmittance | permeability (or reflectance) T changes with wavelengths of irradiation light. FIG. 1 is a diagram showing the relationship between the applied voltage V and the transmittance T for red light, green light, and blue light. However, when the same voltage is applied, the phenomenon that the transmittance T varies depending on the color of light. There is. For this reason, for example, even if a constant voltage is applied to perform black display, specific light leaks, and there is a problem that the original black color cannot be displayed. Further, there is a problem that the contrast becomes low due to such light leakage. Furthermore, even if another intermediate color is to be displayed, the relationship between the voltage and the light transmittance is different for each color, so that the desired intermediate color cannot be displayed and the image quality deteriorates.
[0014]
SUMMARY An advantage of some aspects of the invention is that it provides a liquid crystal device that prevents deterioration in image quality.
[0015]
[Means for Solving the Problems]
The present invention has been made in view of these circumstances, a pair of substrates disposed with a predetermined spacing, placed a nematic liquid crystal in a bend alignment state between the pair of substrates, and the nematic liquid crystal An active matrix type liquid crystal element having a pair of electrodes arranged so as to sandwich the light source, and an illumination device that sequentially irradiates light of different colors to the liquid crystal element, and is synchronized with the irradiation of the light In a liquid crystal device that recognizes a full-color image by switching light with the liquid crystal element, the retardation amount varies depending on the wavelength of light, and the slow axis is arranged orthogonal to the slow axis of the nematic liquid crystal. and the phase difference member, the lighting device to realize the transmittance or reflectance of the target applying voltage having different according to the color of light to be irradiated to the pair of electrodes And a driving means for causing the switching of light to the liquid crystal element by a, and the drive means, the voltage applied to the pair of electrodes when the or dark state when the liquid crystal element in the bright state Is set independently for each color of light emitted by the illumination device, depending on the retardation amount of the phase difference member, in a bright state and a dark state of the liquid crystal element .
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 4.
[0018]
As shown by reference numeral 1 in FIG. 2, the liquid crystal device according to the present invention includes a liquid crystal element P that switches light for each pixel, and an illumination device B that sequentially irradiates the liquid crystal element P with light of different colors. And.
[0019]
Among these, as shown in FIG. 3, the liquid crystal element P has a pair of substrates 2a and 2b arranged in a state where a predetermined gap is provided, and a bend alignment state arranged between the pair of substrates 2a and 2b. The nematic liquid crystal 3 and a pair of electrodes 4a and 4b arranged so as to sandwich the nematic liquid crystal 3 therebetween.
[0020]
The liquid crystal element P to which the present invention is applied may be a transmissive type that switches transmitted light or a reflective type that switches reflected light. Both the substrates 2a and 2b and the electrodes 4a and 4b may be transparent, and polarizing plates (not shown) may be disposed on both sides of the liquid crystal element P, respectively. In the case of a reflective type, any one of the substrates 2a or 2b or the electrodes 4a or 4b may be transparent, only one polarizing plate may be provided, and a reflecting plate may be disposed to reflect light.
[0021]
Incidentally, the liquid crystal device 1 according to the present invention includes a phase difference member (not shown) having a slow axis orthogonal to the slow axis of the liquid crystal 3. Here, in the liquid crystal element (bend alignment cell) using the nematic liquid crystal 3 in the bend alignment state, when the voltage V applied to the pair of electrodes 4a and 4b is changed, the birefringence amount R of the liquid crystal 3 also changes. The characteristic curve indicating the relationship between the birefringence amount R and the applied voltage V does not intersect the vertical axis as illustrated by the symbol R ₁ (= R _LC ) in FIG. 4, but by providing the phase difference member, The characteristic curve is changed as indicated by the symbol R ₂ (= R _LC −R _C ) after being reduced by a certain amount R _C so as to intersect the vertical axis. Then, by providing the phase difference member as described above, when the liquid crystal element P to the transmission type, the birefringence amount _{R 2 (= R LC -R C} ) and the relationship between the transmittance T is T = sin ² {π (R _LC −R _C ) / λ}
Here, R _LC ; retardation amount R _{C of} liquid crystal 3; retardation amount λ of retardation member In the case where the wavelength of the irradiation light is set so that the liquid crystal element P is of a reflective type, the relationship between the birefringence amount R ₂ (= R _LC −R _C ) and the reflectance T is
T = cos ² {π · 2 (R _LC −R _C ) / λ}
Here, R _LC ; retardation amount R _{C of} liquid crystal 3; retardation amount λ of retardation member The wavelength of the irradiation light is set.
[0022]
In the case where the liquid crystal element P is a transmissive type,
_{π (R LC -R C) /} λ = 0 That is, _R LC _-R C = 0
In the dark state,
_{π (R LC -R C) /} λ = π / 2 or - [pi] / 2
_{That, R LC -R C = ± λ} / 2
I am trying to take a bright state. Further, when the liquid crystal element P is a reflection type, in any wavelength of light,
_{π (R LC -R C) /} λ = 0 That is, _R LC _-R C = 0
In the bright state,
π (R _LC −R _C ) / λ = π / 4 or −π / 4
_{That, R LC -R C = ± λ} / 4
I try to take a dark state.
[0023]
Incidentally, in the nematic liquid crystal 3 in the bend alignment state, as shown in FIG. 3, the liquid crystal director at the center of the liquid crystal layer is perpendicular to the substrates 2a and 2b. This can be realized by subjecting 2b to a uniaxial orientation treatment in substantially the same direction.
[0024]
The light switching as described above may be performed by connecting the driving means 5 and 6 to the electrodes 4a and 4b and applying the voltage V as shown in FIG. Is determined in consideration of not only the target light transmittance and light reflectance but also the wavelength (that is, color) of light. For example, FIG. 1 illustrates the relationship between the transmittance T and the applied voltage V using the wavelength (color) of light as a parameter. The relationship between the transmittance T and the applied voltage V is shown in FIG. It is possible to memorize every time and determine the applied voltage based on the color of the irradiated light and the target transmittance. For example, when it is desired to obtain a transmittance T of 50%, the applied voltage value may be changed to V ₁ , V ₂ , V ₃ depending on the color of light. Thereby, the target light transmittance and light reflectance can be realized regardless of the wavelength of light.
[0025]
According to the present embodiment, light of different colors is sequentially irradiated from the illumination device B to the liquid crystal element P, and light is switched for each pixel by the liquid crystal element P in synchronization with the irradiation of the light. Thus, images of different colors are sequentially recognized, and by using the afterimage phenomenon of human eyes, these images are mixed and recognized as a full color image.
[0026]
Next, the effect of this embodiment will be described.
[0027]
According to the present embodiment, since the liquid crystal 3 has a bend alignment and a very fast response speed, a high luminance display is possible even though the field sequential method has a short field period. Further, since the response speed of the liquid crystal 3 is very fast, it can be reset in a short time, and color mixing can be reduced.
[0028]
On the other hand, according to the present embodiment, color display can be performed with only one pixel, and the definition can be made higher than when color display is performed with a combination of a plurality of pixels as in the micro color filter system. Can do. In addition, the image brightness can be increased by increasing the aperture ratio. Furthermore, since it is not necessary to provide a color filter for each pixel, the manufacturing yield can be improved.
[0029]
On the other hand, according to the present embodiment, the target light transmittance and light reflectance can be realized regardless of the wavelength of light, the display color can be accurate, and the image quality can be improved. . For example, when displaying black, the light transmittance and light reflectance of each pixel are set to 0%, and the original black (original black, not bluish black or greenish black) can be displayed. In addition, when an intermediate color other than black is displayed, a color excellent in color balance can be displayed. Furthermore, there is no problem that the contrast is lowered due to light leakage.
[0030]
【Example】
Hereinafter, the present invention will be described in more detail with reference to examples.
[0031]
Example 1
In this example, an active matrix type liquid crystal panel P shown in FIG. 5 was produced.
[0032]
That is, on one substrate 2b, an a-Si TFT 10 having a silicon nitride film as a gate insulating film was formed for each pixel, and a transparent electrode 4b made of an ITO film of 1300 mm was connected to the TFT 10. Further, on the other substrate 2a (see FIG. 3), a transparent electrode 4a is formed from a 1300 mm ITO (Indium Tin Oxide) film, and a 400 mm thick TFT alignment film JALS2022 (manufactured by JSR) is used. An orientation control film (not shown) was formed. The screen size was 3 inches, the number of pixels was 800 × 600, and the distance between the substrates was 8 μm. As the nematic liquid crystal 3, a commercially available liquid crystal material KN5027 (manufactured by Chisso Corporation) was used.
[0033]
Further, the backlight device B in the present embodiment was configured by combining three devices as shown in FIG. Here, the apparatus shown in FIG. 6 is configured by connecting seven LEDs 20, a transistor 21, and a power supply 22 in series, and a waveform generator 23 is connected to the transistor 21. The seven LEDs 20 shown in the figure were irradiated with red light, another seven LEDs were irradiated with blue light, and another seven LEDs were irradiated with green light. As the RGB light source material, GaAIAs was used for R, and GaN was used for G and B. Further, the gate voltage of the transistor 21 is adjusted by the waveform generator 23 to control the current to the LED 20. Furthermore, the dominant wavelengths of the respective colors were 453 nm, 549 nm and 640 nm, respectively. In this way, by using an LED having a response time on the order of several μS as a light source, it is possible to provide a backlight light source in which RGB colors are sequentially lit within a short frame period of several ms.
[0034]
From the voltage-retardation characteristics at each RGB wavelength of the liquid crystal layer, the retardation of the liquid crystal layer at a blue wavelength of 453 nm with a bend holding voltage of 1.16 V was 712 nm. In this embodiment, a retardation plate (a retardation member) made of a polycarbonate material having a wavelength dispersion characteristic of a retardation amount of 712 nm for a blue wavelength of 453 nm, a retardation amount of 698 nm for a green wavelength of 549 nm, and a retardation amount of 678 nm for a red wavelength of 640 nm. ) Was used.
[0035]
As described above, the voltage retardation characteristics at each RGB wavelength of the liquid crystal layer, and the retardation amount at each RGB wavelength of the retardation plate,
π (R _LC −R _C ) / λ = 0
π (R _LC −R _c ) / λ = π / 2
And the voltage values for the bright state and the dark state are calculated, and the results are as follows: bright state 4.0V (blue), 8.0V (green), 13.5V (red)
Dark state 1.16V (blue), 1.43V (green), 1.6V (red)
It becomes. For the voltage retardation characteristics at each RGB wavelength used for calculation, it is preferable to use measured values at the respective RGB wavelengths in consideration of the wavelength dependence of the birefringence of the liquid crystal material.
[0036]
Here is a supplement.
[0037]
Retardation amount R _c of the phase difference member varies depending on the wavelength. In the above example, with respect to the retardation of the blue wavelength of the liquid crystal layer in the bend holding voltage, and setting the retardation amount R _c of the phase difference member. This is because the actual liquid crystal element cannot be driven at a voltage lower than the bend holding voltage, and if the values are adjusted with retardation having a longer wavelength than blue, the optimum voltage at the blue wavelength will be lower than the bend holding voltage. is there. Since the voltage calculated in the above portion is the smallest at the blue wavelength, it is necessary to match it with the bend holding voltage.
[0038]
Next, the flow of signals will be described with reference to FIG.
[0039]
The R analog signal input to the input terminal 30R is converted into a digital signal by an A / D converter (analog / digital converter) 31R, and the intensity level is converted by a level correction circuit 32R. The level correction circuit 32R includes an inverse γ correction circuit and a γ correction path, and is converted into a signal level suitable for the extreme condition of the previous transmittance at the time of γ correction. Similarly, other B signals and G signals are converted into digital signals by A / D converters (analog / digital converters) 31B and 31G, and intensity levels are converted by level correction circuits 32B and 32G. The
[0040]
By the way, these RGB digital signals are input to a P / S converter (parallel / serial converter) 33 together with a synchronizing signal V-Sync, subjected to triple speed processing, and then serially output. The display data, drive voltage, drive signal, and scan data output from the P / S converter 33 are supplied to the liquid crystal panel drivers 5 and 6 and the backlight drive unit 7, respectively.
[0041]
Thus, the R light source is turned on when the R image is displayed, the G light source is displayed when the G image is displayed, and the B light source is turned on when the B image is displayed in the same manner. To do. Therefore, a full color image can be displayed by sequentially displaying RGB images displayed by the above processing.
[0042]
Next, the effect of the present embodiment will be described.
[0043]
According to the present embodiment, a desired transmittance can be obtained for each of the three RGB colors, and a contrast of 200 or more can be obtained by suppressing light leakage at each wavelength during black display.
[0044]
According to the present embodiment, since the liquid crystal 3 has a bend alignment and a very high response speed, a high-luminance display with a maximum transmittance of about 97% is possible for any color. That is, for the liquid crystal panel manufactured as described above, the maximum transmittance when each color light was irradiated was measured. For example, a light state voltage (that is, 4.0 V) is applied in a state where blue light is irradiated, a light state voltage (that is, 8.0 V) is applied in a state where green light is irradiated, and a red light is irradiated When a light state voltage (that is, 13.5 V) was applied and the transmittance was measured, in each case, about 97% (however, the panel transmitted light intensity at 110 ° C. in which the liquid crystal layer is in an isotropic phase) Is 100%).
[0045]
Further, when the contrast ratio between the bright state and the dark state was measured, a contrast of 200 or more was obtained.
[0046]
(Comparative Example 1)
In the above embodiment, the driving voltage width of each color is changed. In this comparative example, the driving voltage width is fixed.
[0047]
In the liquid crystal panel prepared in Example 1, the voltages for taking the bright state and the dark state during the lighting period of each of the red, green, and blue LEDs were set to 8.0 V and 1.43 V, respectively. When the measurement was performed, the transmittance at each wavelength of RGB was 80%, 97%, and 90%, which was worse than that of Example 1. The contrast when displaying white was about 80.
[0048]
(Example 2)
In this example, a reflective active matrix type liquid crystal panel (liquid crystal element) was prepared by arranging a reflective plate instead of one polarizer. Although the substrate gap was halved, other configurations were the same as in Example 1.
[0049]
In this configuration, the retardation of the liquid crystal layer at a blue wavelength of 453 nm with a bend holding voltage of 1.16 V was 366 nm, based on the voltage-retardation characteristics at each wavelength of RGB of the liquid crystal layer. In this example, a retardation plate made of a polycarbonate material having wavelength dispersion characteristics such that the retardation amount is 366 nm with respect to the blue wavelength 453 nm, the retardation amount 333 nm with respect to the green wavelength 549 nm, and the retardation amount 320 nm with respect to the red wavelength 640 nm is used.
[0050]
As described above, the voltage retardation characteristics at each RGB wavelength of the liquid crystal layer, and the retardation amount at each RGB wavelength of the retardation plate,
π (R _LC −R _c ) / λ = 0
π (R _LC −R _c ) / λ = π / 4
Substituting into, and calculating the voltage values for the bright state and dark state, respectively, the bright state is 4.0V (blue), 7.8V (green), 11.5V (red)
Dark state 1.17V (blue), 1.43V (green), 1.6V (red)
It becomes.
[0051]
The panel reflected light intensity at 110 degrees Celsius in which the liquid crystal layer is in an isotropic phase with the voltage value in the bright state was set to 100%, light was incident from the normal direction of the panel, and the reflectance in total reflection was measured. However, it was about 97% at each wavelength of RGB.
[0052]
Further, when the contrast ratio between the bright state and the dark state was measured, a contrast of 100 or more was obtained during white display.
[0053]
(Comparative Example 2)
In the liquid crystal panel prepared in Example 2, the voltages for taking the bright state and the dark state during the lighting period of the red, green, and blue LEDs were set to 7.8 V and 1.43 V, respectively. When the measurement was performed, the reflectance at each wavelength of RGB was 85%, 97%, and 92%, which deteriorated. The contrast when displaying white was about 70.
[0054]
【The invention's effect】
As described above, according to the present invention, since the liquid crystal has a bend alignment and a very high response speed, a high luminance display is possible even though the field sequential method has a short field period. In addition, since the response speed of the liquid crystal is very fast, it can be reset in a short time and color mixing can be reduced.
[0055]
On the other hand, according to the present invention, color display can be performed with only one pixel, and the definition can be increased as compared with the case where color display is performed with a combination of a plurality of pixels as in the micro color filter system. . In addition, the image brightness can be increased by increasing the aperture ratio. Furthermore, since it is not necessary to provide a color filter for each pixel, the manufacturing yield can be improved.
[0056]
On the other hand, according to the present invention, the target light transmittance and light reflectance can be realized regardless of the wavelength of light, the display color becomes accurate, and the image quality can be improved. For example, when displaying black, the light transmittance and light reflectance of each pixel are set to 0%, and the original black (original black, not bluish black or greenish black) can be displayed. In addition, when an intermediate color other than black is displayed, a color excellent in color balance can be displayed. Furthermore, there is no problem that the contrast is lowered due to light leakage.
[Brief description of the drawings]
FIG. 1 is a diagram showing the relationship between transmittance T and applied voltage V using the wavelength of light as a parameter.
FIG. 2 is a block diagram for explaining a schematic structure of a liquid crystal device.
FIG. 3 is a cross-sectional view illustrating a structure of a liquid crystal panel.
FIG. 4 is a graph showing the relationship between applied voltage and birefringence amount.
FIG. 5 is a plan view showing an entire structure of a liquid crystal panel.
FIG. 6 is a block diagram for explaining a structure of a backlight device.
FIG. 7 is a block diagram for explaining the flow of signals.
FIG. 8 is a block diagram illustrating an example of the structure of a conventional liquid crystal device.
FIG. 9 is a timing chart illustrating an example of a method for driving a liquid crystal device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Liquid crystal device 2a, 2b Substrate 3 Nematic liquid crystal 4a, 4b Electrode 5, 6 Liquid crystal panel driver (driving means)
B Backlight device (lighting device)
P Liquid crystal panel (liquid crystal element)

Claims (4)

A pair of substrates disposed with a predetermined spacing, bend disposed nematic liquid crystal orientation state, and an active matrix type having a pair of electrodes disposed so as to sandwich the nematic liquid crystal between said pair of substrates A liquid crystal element and a lighting device that sequentially irradiates the liquid crystal element with light of different colors, and the light is switched by the liquid crystal element in synchronization with the irradiation of the light. In a liquid crystal device that recognizes
Retardation members having different retardation amounts depending on the wavelength of light, and arranged with the slow axis orthogonal to the slow axis of the nematic liquid crystal ,
Driving means for causing the liquid crystal element to perform light switching by applying to the pair of electrodes a voltage different according to the color of light emitted by the illuminating device so as to achieve a target transmittance or reflectance ; And comprising
The driving means sets the voltage applied to the pair of electrodes when the liquid crystal element is in a bright state and a dark state to the retardation amount of the retardation member for each color of light irradiated by the illumination device. In response, the liquid crystal element is set independently in a bright state and a dark state ,
A liquid crystal device characterized by that. The liquid crystal element has a relationship of light transmittance T, liquid crystal retardation amount R _LC , retardation amount _RC offset by the retardation member , and light wavelength λ.
^{_{T = sin 2 {π (R}} LC -R C) / λ}
Ri transmission-type Der is,
In any wavelength of light,
π (R _LC −R _C ) / λ = 0
In the dark state,
_{π (R LC -R C) /} λ = π / 2 or - [pi] / 2
Take a bright state in the
The liquid crystal device according to claim 1. In the liquid crystal element, the relationship between the reflectance T of light, the retardation amount R _{LC of the} liquid crystal, the retardation amount R _C offset by the retardation member , and the wavelength λ of the light,
T = cos ² {π · 2 (R _LC −R _C ) / λ}
Is a reflective type,
In any wavelength of light,
π (R _LC −R _C ) / λ = 0
In the bright state,
π (R _LC −R _C ) / λ = π / 4 or −π / 4
In the dark state,
The liquid crystal device according to claim 1 . The light sequentially irradiated by the lighting device is three colors of blue, green, and red,
The driving means reduces the voltage applied to the pair of electrodes when the liquid crystal element is in a bright state or a dark state when the light applied to the liquid crystal element is blue light among three colors;
The liquid crystal device according to claim 1 , wherein the liquid crystal device is a liquid crystal device.

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