JP3184693B2 - Liquid crystal display and liquid crystal display - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device which performs color display by reflected light using cholesteric liquid crystal.

[0002]

2. Description of the Related Art A reflection type liquid crystal display device does not require a light source and consumes a small amount of power. Therefore, it can be said that a reflection type liquid crystal display device is more suitable for application to portable information equipment than a transmission type liquid crystal display device.

[0003] As such a conventional reflective liquid crystal display device, for example, Proceedings of SID, Vol.
(1986) p.223-227, a reflection type liquid crystal display device utilizing cholesteric-nematic phase transition is known.

[0004] Proceedings of SID, Vol. 27 (1986) p. 2
In the reflection-type liquid crystal display device described in 23-227, a liquid crystal composition exhibiting a cholesteric phase in the absence of an electric field is mixed with a dichroic dye having a different light absorption depending on the orientation direction, and a guest-host type. None, an electric field in a direction perpendicular to the substrate holding the liquid crystal composition (in a direction parallel to the helical axis of the cholesteric liquid crystal composition) is applied to cause a phase transition to a nematic phase, thereby causing dichroic dye molecules. By changing the orientation direction, a color different from that when no electric field was applied was displayed.

In addition, an electric field in a direction perpendicular to the substrate has been applied by charging and discharging a load approximated by a parallel plate type capacitor element sandwiching a liquid crystal composition.

As described in Japanese Patent Application Laid-Open No. 49-74438, a color display in a conventional liquid crystal display device is of a light absorption type corresponding to the three primary colors of light, red, green and blue. It has been realized by disposing a micro color filter and adding light of the light transmitted through the micro color filter.

[0007]

The Proceedings of S
According to the reflective liquid crystal display device described in ID, Vol. 27 (1986) p. 223-227, the amount of dichroic dye that can be mixed in the liquid crystal composition has an upper limit, There is a problem that it is difficult to obtain a sufficient contrast ratio because the orientation directions of the chromatic dye molecules are not completely aligned. When a polarizing plate is used to increase the contrast ratio, the polarizing plate has the function of extracting only polarized light in a certain direction from an unpolarized light and oscillating the electric field and absorbing polarized light in another direction. There is a problem that the use efficiency is reduced and the display screen is darkened.

In addition, since the long axis of the liquid crystal composition molecules rises from the surface of the substrate, there arises a problem that a domain boundary is generated at a portion where the rising direction is different and display is disturbed.

Further, when the above-mentioned micro color filter is used to realize a color display, there is a problem that the light use efficiency is inevitably reduced and the display screen becomes dark.

Further, there is a problem that power consumption is large because an electric field is applied by charging and discharging a load approximated by a parallel plate type capacitor element sandwiching a liquid crystal composition. Further, in such an application method, it is necessary to provide electrodes on both sides of the liquid crystal layer, so that there is a problem that visibility is deteriorated depending on a direction in which the display surface is viewed.

As for a liquid crystal display device using a nematic liquid crystal composition, as described in JP-B-63-21907, an electric field in a direction parallel to the substrate is generated by a pair of comb-like electrodes provided only on one side of a liquid crystal layer. A technique for changing the orientation of a nematic liquid crystal composition by applying a voltage is known.

SUMMARY OF THE INVENTION An object of the present invention is to provide a reflective type color liquid crystal display device capable of favorably displaying bright colors.

[0013]

In order to achieve the above object, the present invention comprises a pair of substrates opposed to each other at a fixed interval,
In the gap between the pair of substrates, a cholesteric liquid crystal composition whose helical axis is filled so as to be substantially perpendicular to both surfaces of the pair of substrates, and the other of at least one of the pair of substrates. And an electrode group provided on the surface on the substrate side of the substrate, both surfaces on the other substrate side of the pair of substrates,
The orientation azimuthal angle of the cholesteric liquid crystal composition molecules is treated so as to be constant with respect to the surface, and the electrode group applies an electric field in a direction parallel to the surfaces of the pair of substrates to the cholesteric liquid crystal composition. The helical pitch of the cholesteric liquid crystal composition is arranged on the surface of the other substrate side of at least one of the pair of substrates, and the helical pitch is determined by the electric field applied by the electrode group. A first liquid crystal display characterized by being controlled is provided.

Further, in such a liquid crystal display, the electrode group includes a first electrode group periodically arranged at a constant interval on the surface of the substrate, and the first electrode group and the first electrode group. Of 1
A second electrode group periodically arranged at a position shifted by / 6;
A third electrode group periodically arranged at a position 2/6 of the interval in the same direction as the second electrode with respect to the first electrode group, and a third electrode group with respect to the first electrode group. A fourth electrode group periodically arranged in the same direction as the second electrode at a position shifted by 3/6 of the distance, and a first electrode group in the same direction as the second electrode with respect to the first electrode group; A fifth electrode group periodically arranged at a position shifted by 4/6 of the interval, and a position shifted by 5/6 of the interval in the same direction as the second electrode with respect to the first electrode group. A first electrode group and the second electrode group are connected to a seventh electrode arranged at an arbitrary position; The fourth electrode group and the fifth electrode group
Are connected to an eighth electrode disposed at an arbitrary position, thereby providing a second liquid crystal display.

Further, the present invention uses two of the first or second liquid crystal display devices, and uses the two cholesteric liquid crystal compositions as a spontaneous spiral pitch p0 and an average refractive index n.
The first liquid crystal display device includes two liquid crystal displays stacked on each other, in which the product is equal to the product and the spiral twist is in the opposite direction.

In the present invention, the three cholesteric first displays are used, and the cholesteric liquid crystal composition of each liquid crystal display of each set is converted into a spontaneous spiral pitch p0 and an average refractive index n. 380 (nm) ≦ n ・ p0 ≦ 530 (nm), 480 (nm) ≦ n ・ p0 ≦ 630 (nm), 570 (nm) ≦ n ・ p0 ≦ 800 (nm), each liquid crystal display is stacked in any order so that the substrates of each liquid crystal device are parallel, and a visible light absorber is stacked on each liquid crystal display. A second liquid crystal display device provided in a lower layer is provided.

Furthermore, the amount of light incident on the liquid crystal display or the liquid crystal display device or the amount of light reflected from the liquid crystal display is reflected by a predetermined area on a plane parallel to the substrate of the plurality of liquid crystal displays. Transmission type liquid crystal display device
It is preferable to provide on the upper part. The distance d between the pair of substrates of each of the liquid crystal displays is always a spontaneous spiral pitch p0 of the cholesteric liquid crystal composition at an arbitrary point, and the cholesteric liquid crystal composition on the surface of one of the pair of substrates. For an angle difference φ between the orientation azimuth of the compound molecule and the orientation azimuth of the cholesteric liquid crystal composition molecule on the surface of the other substrate and a positive constant integer m, the following expression is given. 2π) | <1/4. Further, each of the above-described liquid crystal displays and the liquid crystal display device may further include a collimating unit disposed above the liquid crystal display, which is refracted so as to be incident on the substrate of the liquid crystal display substantially perpendicularly. desirable.

[0018]

According to the first liquid crystal display, when a voltage is applied between the electrodes, an electric field is applied to the cholesteric liquid crystal composition in a direction substantially parallel to the substrate surface. Since the electric field receives a force such that the orientation direction of the molecular long axis of the cholesteric liquid crystal composition rotates in a plane parallel to the substrate surface, the helical pitch p of the cholesteric liquid crystal composition becomes larger than the spontaneous pitch p0. Since the center wavelength λ of selective reflection of light in the direction of the helical axis of the cholesteric liquid crystal composition, the spiral pitch p of the cholesteric liquid crystal composition, and the average refractive index n, λ = n · p, As the helical pitch of the cholesteric liquid crystal composition increases, the central wavelength of selective reflection of light increases. Accordingly, the color selectively reflected is controlled by the voltage applied to the electrode group,
Color display can be realized.

Further, since the major axis of the cholesteric liquid crystal composition molecule only rotates in a plane parallel to the substrate surface due to an electric field in a direction substantially parallel to the substrate surface, it does not move up from the substrate surface. No domain boundary occurs due to the different rising directions. In particular, the distance d between a pair of opposed substrates is always | d / p0- (mπ + φ) / (2π) |
If the setting is made so as to satisfy <１ ／, a domain boundary due to a difference in the number of turns does not occur. Here, the domain boundary is a portion where the orientation vector (director) of the liquid crystal composition changes spatially discontinuously. Further, if it is provided with a parallel light converting means disposed above the liquid crystal display, which is refracted so as to be incident on the substrate of the liquid crystal display substantially perpendicularly,
Variations in visibility due to differences in viewing angles can be reduced.

According to the second liquid crystal display device,
For example, using a cholesteric liquid crystal composition in which the central wavelength of the selective reflection at the spontaneous pitch is in the blue region, the absolute value of the potential difference between the seventh electrode and the third electrode, and the absolute value of the potential difference between the eighth electrode and the 6 is always equal to the absolute value of the potential difference between the electrodes 6 and 6, and the selective reflection center wavelength becomes a value that becomes red / green.
The absolute value of the potential difference between the third electrode and the eighth electrode is always equal to the absolute value of the potential difference between the sixth electrode and the first electrode, and the selective reflection center wavelength is green / By applying an alternating voltage of a predetermined amplitude to each of the third electrode, the sixth electrode, the seventh electrode, and the eighth electrode so as to obtain a red value, the light of 3 The primary color red,
A reflection pattern in which blue and green are alternately and periodically arranged can be realized. Accordingly, a transmissive liquid crystal display device that controls the amount of light incident on the liquid crystal display device or the amount of light reflected from the liquid crystal display device for each predetermined region on a surface parallel to the substrate of the plurality of liquid crystal displays is disposed above the transmissive liquid crystal display device. , The amounts of red, blue and green light can be arbitrarily controlled to realize full-color display.

Next, according to the first liquid crystal display device,
The helical twist can reflect both clockwise polarized light and counterclockwise polarized light by the right-handed and left-handed cholesteric liquid crystal compositions, thereby improving the light use efficiency.

Further, according to the second liquid crystal display, for example, two liquid crystal displays selected from the three liquid crystal displays are sequentially selected so that the liquid crystal display devices not selected are sequentially replaced. By sequentially applying a voltage for generating the electric field to the electrodes from the power supply, it is possible to realize a reflection pattern in which the three primary colors of light, red, blue and green, are alternately and periodically reflected. Accordingly, a transmissive liquid crystal display device that controls the amount of light incident on the liquid crystal display device or the amount of light reflected from the liquid crystal display device for each predetermined region on a surface parallel to the substrate of the plurality of liquid crystal displays is disposed above the transmissive liquid crystal display device. If it prepares for, the red, blue, green,
The amount of green light can be arbitrarily controlled, and a full-color display can be realized.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the liquid crystal display according to the present invention will be described below.

[Embodiment 1] First, a first embodiment will be described.

FIG. 1a shows a cross section of the liquid crystal display device according to the first embodiment.

As shown in the figure, in the liquid crystal display device according to the first embodiment, strip-shaped metal electrodes 1 and 2 are formed on the surface of one of a pair of light-transmitting plastic substrates 3. A polyimide resin alignment film 4 is formed on a surface of a pair of substrates 3 so as to cover the electrodes 1 and 2.

The alignment film 4 is subjected to a rubbing treatment so that the molecular long axis direction of the liquid crystal composition 5 on the substrate surface is oriented substantially perpendicular to the long sides of the electrodes 1 and 2. That is, the angle difference φ between the orientation azimuths of the liquid crystal composition molecules 5 on the respective substrate surfaces of the pair of substrates 3 was set to 0. The angle difference φ was, as shown in FIG. 2, the angle difference in the molecular long axis direction on the respective substrate surfaces of the pair of substrates 3.

A pair of substrates 3 are fixed at a constant distance d = 5 (μm) by a plastic bead spacer (not shown).
The gap between the pair of substrates 3 is
The dielectric anisotropy is positive, the average refractive index n is 1.5, the spiral twist is right-handed, and the spontaneous spiral pitch p0 is 28.
The liquid crystal composition 5 having a cholesteric phase of 0 (nm) is filled. As such a liquid crystal composition, for example, a mixture of cholesteryl chloride and cyanopentyl biphenyl can be used.

The distance d between a pair of substrates is | d / p0- (mπ + φ) / (2π) | <1/4. . . An error of the interval d was set so as to satisfy (Equation 1). By doing so, the number of turns of the helix of the liquid crystal composition filled in the same electric field between the pair of substrates is the same, and the direction of the molecular long axis is substantially the same as the long side direction of the electrodes 1 and 2. It can be oriented in the same direction in one of two mutually perpendicular perpendicular directions.

Here, m is a positive constant integer, and here, m is set to 18.

Then, an AC power supply 6 capable of changing the amplitude of the output voltage was connected to the electrodes 1 and 2 via a switching element 60 for controlling the voltage applied to the electrodes 1 and 2.

In the liquid crystal display device having such a structure,
When no voltage is applied between the electrodes 1 and 2, the helical pitch of the cholesteric liquid crystal composition 5 becomes p shown in FIG. 1A. Since the molecular long axis direction of the cholesteric liquid crystal composition 5 is defined on the surface of the alignment film 4 in a direction substantially perpendicular to the long side direction of the electrodes 1 and 2, the pair of substrates 3 opposed to each other at a constant interval d is formed. The spiral pitch p of the cholesteric liquid crystal composition 5 in the state of being filled in the gap is the spontaneous pitch p.
Deviates slightly from 0.

In this state, from the properties of the cholesteric liquid crystal composition 5, the helical pitch p of the cholesteric liquid crystal composition 5 in the light L1 incident on the liquid crystal display device 8 indicates that λ = n · p. . . (Equation 2) The clockwise circularly polarized light L2 in the wavelength region centered on the central wavelength λ of the selective reflection is selectively reflected. The clockwise circularly polarized light is selectively reflected because the helical twist of the cholesteric liquid crystal composition 5 is right-handed. As described above, n represents the average refractive index of the cholesteric liquid crystal composition. Here, when no voltage was applied between the electrodes 1 and 2, the central wavelength λ of the selective reflection was 417 (nm).

Next, when the switching element 60 is turned on and a voltage is applied between the electrodes 1 and 2 from the AC power supply 6,
An electric field 7 substantially parallel to the surfaces of the pair of substrates 3 is generated, and the direction of the molecular long axis of the cholesteric liquid crystal composition 5 is applied to the applied electric field 7.
The spiral pitch of the cholesteric liquid crystal composition 5 changes from p in FIG. 1A to p ′ in FIG. 1B.

Accordingly, the clockwise circularly polarized light L2 in the wavelength region centered on the central wavelength λ of the selective reflection determined by λ = n · p ′
Is selectively reflected, and light L3, which is a combination of left-handed circularly polarized light in the same wavelength region as the selectively reflected light L2 and light other than the wavelength region of the selectively reflected light L2, is transmitted.

FIG. 3 shows a cholesteric liquid crystal composition when the amplitude of the output voltage from the AC power supply 6 is changed while the switching element 60 is turned on and a voltage is applied between the electrodes 1 and 2 from the AC power supply 6. 5 shows a relationship between the electric field 7 applied to the cholesteric liquid crystal composition 5 and the spiral pitch of the cholesteric liquid crystal composition 5.

As shown, when the applied electric field is 0, p
The spiral pitch increased stepwise as indicated by the curve 100 as the applied electric field was increased, and when the applied electric field reached the threshold value Eth, the spiral was completely melted and became infinite. Here, the electric field Em− obtained from the smoothed curve 101 created from the applied electric field-spiral pitch characteristic 100 and avoiding both ends of the step on each step.
When the liquid crystal display device 8 is driven at 1, Em-2, Em-3,..., It can operate stably outside the point where the spiral pitch becomes discontinuous. That is, in the electric fields Em-1, Em-2, Em-3,... In which the helical pitch is stable, the helical pitch operates stably outside the unstable point. The distance d between the pair of substrates 3 always satisfies the expression (1) with respect to the angle difference φ between the orientation azimuth angles and the spontaneous pitch p0 of the helix.
1, Em-2, Em-3,..., No domain boundary occurs.

When the liquid crystal display device 8 is driven by such driving, the center wavelength of the selective reflection can be changed as shown in FIG. That is, the selective reflection light L2 of the liquid crystal display device 8 was reflected at the reflectance indicated by the curve 10B1 when no voltage was applied between the electrodes 1 and 2, but the switching element 60 was turned on to switch the electrode 1 from the AC power supply 6. When the amplitude of the output voltage from the AC power supply 6 is changed while a voltage is applied between the cholesteric liquid crystal composition 5 and the helical pitch of the cholesteric liquid crystal composition 5, the curve 10 increases.
It changes so as to be reflected at the reflectances indicated by G1 and 10R1. Along with this, the color of blue, green, and red changes to be reflected and seen.

FIG. 5 shows the wavelength dependence of the transmittance of the liquid crystal display device 8. Curves 10B3, 10G3 in the figure
And 10R3 are the transmittances of the transmitted light L3 in the state where the characteristics of the selective reflection are curves 10B1, 10G1, and 10R1 in FIG. 4, respectively. Like the selective reflection light L2, the transmission light L3 also changes according to the voltage applied between the electrodes 1 and 2 from the AC power supply 6.

In the conventional method in which an electric field in a direction perpendicular to the surface of the substrate is applied to the liquid crystal composition, the long axis of the liquid crystal composition molecules rises from the surface of the substrate. Display is distorted due to domain boundaries. However, according to the first embodiment, the major axis of the liquid crystal composition molecules is in a plane parallel to the substrate surface so that the helical twist of the cholesteric liquid crystal composition can be released by an electric field in a direction substantially parallel to the substrate surface. , And since the image is created so as to satisfy the expression (1), no domain boundary is generated, and the display is favorably maintained.

As described above, according to the first embodiment, the helical pitch p of the cholesteric liquid crystal composition 5 is changed by the electric field 7 substantially parallel to the surfaces of the pair of substrates 3, and the reflection of the liquid crystal display device 8 is changed. The wavelength dependence of the light L2 and the transmitted light L3 can be controlled with extremely high reflectance and transmittance.

Therefore, by arranging the configuration shown in FIG. 1 as a single cell on a matrix, it is possible to realize a bright color liquid crystal display device capable of displaying eight colors of any combination of RGB and having improved light use efficiency. be able to.

Although a plastic substrate is used as the pair of substrates 3 in the first embodiment, any substrate having light transmittance may be used. For example, a glass substrate may be used. Further, although metal electrodes are used as the electrodes 1 and 2, any material having conductivity may be used, and a light-transmitting oxide such as ITO (indium tin oxide) may be used. Further, although the electrodes 1 and 2 are formed only on the surface of one of the pair of substrates 3, the effect is not changed even if they are formed separately on both substrates. In addition, although a polyimide resin is used as the alignment film 4, any member having a function of uniformly aligning the cholesteric liquid crystal composition 5 may be used, and for example, polyamic acid may be used. Further, the direction of the molecular long axis of the liquid crystal composition 5 on the substrate surface was oriented substantially perpendicular to the long sides of the electrodes 1 and 2 by rubbing treatment, but the orientation direction is arbitrary and the liquid crystal composition 5 is most uniform. The orientation may be set in a direction that facilitates the orientation, and the orientation treatment may be performed by a method other than the rubbing treatment. Further, the angle difference φ between the orientation azimuths of the liquid crystal composition molecules 5 on the respective substrate surfaces of the pair of substrates 3 and the distance d between the pair of substrates 3 facing each other are also arbitrary as long as the expression (1) is satisfied. The threshold value Eth may be changed to be set to an appropriate value. As the cholesteric liquid crystal composition to be used, any cholesteric liquid crystal composition can be used as long as the operating temperature range, the temperature coefficient of the helical pitch, and the like have appropriate values.

[Embodiment 2] Hereinafter, a second embodiment of the present invention will be described.

In the second embodiment, a cholesteric liquid crystal having a negative dielectric anisotropy is used instead of the cholesteric liquid crystal composition having a positive dielectric anisotropy in the liquid crystal display device according to the first embodiment. The composition 5 is filled in a gap between a pair of substrates 3.

As shown in FIG.
Is turned on to apply a voltage between the electrodes 1 and 2 from the AC power supply 6, an electric field 7 substantially parallel to the surfaces of the pair of substrates 3 is generated, and the direction of the molecular short axis of the cholesteric liquid crystal composition 5 The spiral pitch of the cholesteric liquid crystal composition 5 changes from p to p ′.
Accordingly, as in the first embodiment, as the applied electric field 7 is increased, the colors of blue, green, and red are changed so as to be reflected and viewed.

Embodiment 3 Hereinafter, a third embodiment of the present invention will be described.

The third embodiment is different from the first embodiment in that the cholesteric liquid crystal composition in which the helical twist is left-handed is replaced by the cholesteric liquid crystal composition in which the helical twist is right-handed. 5 is filled in the gap between the pair of substrates 3.

As such a liquid crystal composition, for example, there is a mixture of cholesteryl myristate and cyanopentyl biphenyl.

According to the liquid crystal display device of the third embodiment, when the switching element 60 is turned on and a voltage is applied between the electrodes 1 and 2 from the AC power supply 6, an electric field substantially parallel to the surfaces of the pair of substrates 3 is obtained. 7 is generated, and the direction of the molecular long axis of the cholesteric liquid crystal composition 5 is easily oriented in the direction of the applied electric field 7, so that the spiral pitch of the cholesteric liquid crystal composition 5 changes from p to p '. Light L1 incident on the liquid crystal display device 8
Among them, the helical twist of the cholesteric liquid crystal composition 5 is left-handed, so that the circularly polarized light L2 that is selectively reflected is the central wavelength of the selective reflection determined by (Equation 2) by the spiral pitch p of the cholesteric liquid crystal composition 5. The light L3 becomes left-handed circularly polarized light in a wavelength region centered on λ, and light L3 that is a combination of right-handed circularly polarized light in the same wavelength region as the selectively reflected light L2 and light other than the wavelength region of the selectively reflected light L2 is transmitted. .

The other points are the same as in the first embodiment.

Embodiment 4 Hereinafter, a fourth embodiment of the present invention will be described.

FIG. 7 shows a cross section of a liquid crystal display device according to the fourth embodiment.

The liquid crystal display device according to the fourth embodiment includes a liquid crystal display device 8a according to the first embodiment in which the helical twist is filled with the cholesteric liquid crystal composition 5a having a right-handed twist, and a left-handed helical twist. When the liquid crystal display device 8b according to the third embodiment filled with the cholesteric liquid crystal composition 5b is viewed from a direction perpendicular to the display surface, the pattern of the electrodes 1 and 2 of the first liquid crystal display device 8a and the second The electrodes 1 and 2 of the liquid crystal display device 8b are stacked and arranged so as to overlap each other.

By arranging the electrodes of each liquid crystal display device so as to overlap each other, the incident external light L1 is blocked by the electrodes 1 and 2 of the first liquid crystal display device 8a. 2 and the electrodes 1 and 2 of the liquid crystal display device 8b.
Not be interrupted by Therefore, the ratio at which the incident external light L1 is blocked by the strip-shaped electrodes 1 and 2 is kept low, and the light use efficiency is improved.

Now, of the external light L1 incident on the first liquid crystal display device 8a, clockwise circularly polarized light in a wavelength region centered on the central wavelength of selective reflection determined by (Equation 2) is selectively reflected,
The remaining light is transmitted. Of the remaining light, counterclockwise circularly polarized light in a wavelength region centered on the central wavelength of the selective reflection determined by (Equation 2) is selectively reflected by the second liquid crystal display device 8b, and further transmits the remaining light L3. . Second liquid crystal display device 8b
Since the traveling direction of the counterclockwise circularly polarized light selectively reflected in the step (1) is reversed, it passes through the first liquid crystal display device as it is.

Therefore, the reflected light L2 is a part of the cholesteric liquid crystal compositions 5a and 5a of the incident external light L1.
All the light in the wavelength region centered on the central wavelength of selective reflection determined by the average refractive index of b and the pitch of the helix.

Accordingly, when the central wavelengths of the selective reflection of the first and second liquid crystal display devices are changed while keeping the same, FIG.
As shown in the figure, the selective reflection light L2 is reflected at the reflectance indicated by the curve 10B2 when no voltage is applied between the electrodes 1 and 2, but when the voltage applied between the electrodes 1 and 2 is changed, the cholesteric As the spiral pitch of the liquid crystal compositions 5a and 5b increases, the curves 10G2, 10R
It changes so that it is reflected by the reflectance shown by 2. Accordingly, the color of blue, green, and red changes to reflect and appear accordingly. Further, the selectively reflected light is reflected at twice the light use efficiency as compared with the first embodiment.

FIG. 5 also shows the wavelength dependence of the transmittance of the liquid crystal display device according to the fourth embodiment. Curves 10B4, 10G4, and 10R4 in FIG. 5 are the transmittances of the transmitted light L3 when the selective reflection characteristics are curves 10B2, 10G2, and 10R2 in FIG. 5, respectively. Like the selective reflection light L2, the wavelength dependence of the transmission light L3 also changes according to the voltage applied between the electrodes 1 and 2.

As described above, according to the fourth embodiment, the wavelength dependence of the reflected light L2 and the transmitted light L3 of the liquid crystal display device is twice as high as that of the first embodiment. And the transmittance. In addition, the ratio at which the incident external light L1 is blocked by the strip-shaped electrodes 1 and 2 can be kept low. Therefore, if the configuration shown in FIG. 7 is arranged on a matrix as one cell, it is possible to display eight colors of any combination of RGB.
A bright color liquid crystal display device with improved light use efficiency can be realized.

In the present embodiment, the first liquid crystal display device is arranged above the second liquid crystal display device, but may be arranged in any order. Further, it is not always necessary to apply the same voltage to the first liquid crystal display device and the second liquid crystal display device. Further, the central wavelength of the selective reflection of each of the first liquid crystal display device and the second liquid crystal display device is changed. It is not necessary to make them match in the state where no voltage is applied or in the state where a voltage is applied, and they may be set arbitrarily according to the purpose of use.

Embodiment 5 Hereinafter, a fifth embodiment of the present invention will be described.

In the fifth embodiment, the three liquid crystal display devices 8a, 8b and 8c according to any one of the first to third embodiments, as shown in FIG. The electrodes 1 and 2 are stacked and arranged such that the long sides of the electrodes 1 and 2 face different directions. This makes it difficult for the ratio at which light is blocked by the strip-shaped electrodes 1 and 2 to change depending on the direction in which the display surface is viewed, so that the light use efficiency can be suppressed from being changed in the direction in which the display surface is viewed. Even in this case, a bright color liquid crystal display device can be realized similarly to the fourth embodiment.

The center wavelength of the selective reflection of each liquid crystal display device may be matched in a state where no voltage is applied or in a state where a voltage is applied, and may be set to be different from each other depending on the purpose of use. It may be.

[Embodiment 6] Hereinafter, a sixth embodiment of the present invention will be described.

FIG. 9 shows a cross section of a liquid crystal display device according to the sixth embodiment.

In the sixth embodiment, six liquid crystal display devices 8B
a, 8Bb, 8Ga, 8Gb, 8Ra and 8Rb are stacked and arranged, and a visible light absorber 9 made of a black plastic film is arranged at the lowermost layer. The first liquid crystal display device 8Ba and the second liquid crystal display device 8Bb have an average refractive index n of 1.5 and a spontaneous spiral pitch p0 of 2 respectively.
This is a liquid crystal display device filled with a liquid crystal composition exhibiting a cholesteric phase of 80 (nm). Further, the third liquid crystal display device 8
Ga and the fourth liquid crystal display device 8Gb are liquid crystal display devices filled with a liquid crystal composition exhibiting a cholesteric phase having a spontaneous spiral pitch p0 of 370 (nm), respectively. Each of the liquid crystal display devices 8Rb is a liquid crystal display device filled with a liquid crystal composition exhibiting a cholesteric phase having a spontaneous spiral pitch p0 of 450 (nm).

The spirals of the liquid crystal compositions of the first, third and fifth liquid crystal display devices are right-handed, and the spirals of the liquid crystal compositions of the second, fourth and sixth liquid crystal display devices are left-handed. It is. In other respects, each liquid crystal display has the same configuration as the liquid crystal display shown in the first to third embodiments.

The order of lamination of each liquid crystal display device may be arbitrary.

Now, in such a configuration, in the state where no voltage is applied, the first liquid crystal display device 8Ba and the second liquid crystal display device 8Bb each have a curve 1 in FIG.
The clockwise circularly polarized light Ba and the counterclockwise circularly polarized light Bb in the wavelength region centered on the wavelength of 417 (nm) are selectively reflected at the reflectance of 0B2, and the light is transmitted at the transmittance of the curve 10B4 in FIG.

Similarly, in the third liquid crystal display device 8Ga and the fourth liquid crystal display device 8Gb, the clockwise rotation of the wavelength region centered on the wavelength of 556 (nm) at the reflectance of the curve 10G2 in FIG. Polarized light Ga and left-handed circularly polarized light Gb are selectively reflected, and light is transmitted at the transmittance indicated by curve 10G4 in FIG.

Further, in the fifth liquid crystal display device 8Ra and the sixth liquid crystal display device 8Rb, the clockwise circularly polarized light in the wavelength region centered on the wavelength of 682 (nm) at the reflectance of the curve 10R2 in FIG. Ra and left-handed circularly polarized light Rb are selectively reflected, and light is transmitted at the transmittance indicated by curve 10R4 in FIG. Therefore, in a state where no voltage is applied, all visible light is reflected, and an extremely bright liquid crystal display device is realized.

On the other hand, a voltage is applied to the liquid crystal display devices 8Ba, 8Bb and 8Ga, 8Gb from the AC power supply 6 via the switching element 60 so that the central wavelength of selective reflection of these liquid crystal display devices is in the infrared region. Then, 682 (n
Only the clockwise circularly polarized light Ra and the counterclockwise circularly polarized light Rb in the wavelength region (red region) centered on the wavelength m) are reflected. Also, the liquid crystal display devices 8Ba, 8Bb and 8Ra, 8Rb
When a voltage is applied from the AC power supply 6 via the switching element 60 so that the central wavelength of the selective reflection of these liquid crystal display devices is in the infrared region, the wavelength region around the wavelength of 556 (nm) ( Only the right-handed circularly polarized light Ga and the left-handed circularly polarized light Gb (in the green region) are reflected. When a voltage is applied to the liquid crystal display devices 8Ra, 8Rb and 8Ga, 8Gb from the AC power source 6 via the switching element 60 so that the central wavelength of selective reflection of these liquid crystal display devices is in the infrared region, 417 clockwise circularly polarized light Ba and counterclockwise circularly polarized light B in a wavelength region (blue region) centered on the wavelength of (nm)
Only b is reflected.

Of course, it is also possible to perform reflection in a combination of these wavelength regions. Therefore, if the structure shown in FIG. 9 is made into one cell and arranged in a matrix, the RGB combination of eight colors can be obtained. A color liquid crystal display device capable of displaying can be realized.

On the other hand, 8Ba, 8Bb and 8Ga, 8G
b, a first period in which a voltage is applied from the AC power supply 6 via the switching element 60, and 8Ba, 8Bb and 8R
a, 8Rb through the switching element 60
And a third period in which a voltage is applied to the 8Ga, 8Gb and 8Ra, 8Rb from the AC power supply 6 via the switching element 60 at a cycle of 16.6 (ms), In each liquid crystal display device, the center wavelength of selective reflection is in the infrared region when voltage is applied, and all visible light is transmitted. Therefore, red is used in the first period, blue in the second period, and third period. Then, the phenomenon in which the green color is reflected is changed at high speed.

For example, as shown in FIG.
The same applies if the liquid crystal display devices 8Bb, 8Gb and 8Rb are removed and only clockwise circularly polarized light is used as reflected light. In this case, counterclockwise circularly polarized light Bb is always used.
Since Gb and Rb reach the visible light absorber 9, the light use efficiency is reduced. However, since the number of liquid crystal display devices to be used is reduced to half, the driving circuit, the driving power, and the weight are reduced by half, and the cost and power consumption are reduced. A liquid crystal display device can be provided.
Of course, only counterclockwise polarized light may be used, or different polarized light may be used for each color. The material of the visible light absorber 9 in FIGS. 9 and 10 is arbitrary, and one of a pair of substrates of the lowermost liquid crystal display device among the plurality of stacked liquid crystal display devices is formed of the visible light absorber. You may.

As described above, according to the sixth embodiment, a color display in which the three primary colors of light are alternately reflected at high speed can be realized, so that the full-color liquid crystal display can be realized by the configuration shown in FIG. Can be realized.

That is, as shown in FIG. 11, a visible light absorber 9 made of a black plastic film is laminated below a liquid crystal display device 8 in which the structure shown in FIG. Liquid crystal display device 8
A transmission-type single-color liquid crystal display device 22 using a guest-host mode polymer-dispersed liquid crystal is layered and arranged above.

The electrode pattern in the liquid crystal display device 8 is as follows:
The electrode patterns or the patterns of the light-shielding layers in the transmissive single-color liquid crystal display device 22 are stacked so as to overlap each other when viewed from a direction perpendicular to the display surface.

The row driving circuit 221 and the column driving circuit 22
2. A control circuit 100 for controlling each unit is provided.

In such a configuration, the control circuit 100 controls the liquid crystal display device 8 to alternately change the colors of red, blue, and green sequentially and to reflect the colors repeatedly and at high speed. Further, the control circuit controls the row driving circuit 221 and the column driving circuit 222 according to the RGB image data input from the outside, so that the transmission suitable for each color of the display image pattern on the transmission type monochromatic liquid crystal display device 22 is performed. The rate pattern is realized by the liquid crystal display device 8 in synchronization with the red, blue, and green reflection periods, and controls the amount of transmitted light of each color. Thus, the amount of light selectively reflected by the liquid crystal display device 8 can be arbitrarily controlled. That is, the amount of light in a specific wavelength region can be arbitrarily controlled. Accordingly, a bright full-color liquid crystal display device with improved light use efficiency can be realized.

Although the transmission-type single-color liquid crystal display device 22 uses a guest-host mode polymer dispersed liquid crystal, the transmission-type single-color liquid crystal display device 22 includes a twisted nematic liquid crystal display device and a super twisted nematic liquid crystal display device. A device, a cholesteric-nematic phase transition type guest-host mode liquid crystal display device, a dynamic scattering mode liquid crystal display device, or the like may be used. Further, a display device using an inorganic substance can be used as long as it is a transmission type single color display device.

FIG. 11 shows the case where the liquid crystal display device shown in FIG. 10 is used as the liquid crystal display device 8. However, if the liquid crystal display device shown in FIG. Can be realized.

[Embodiment 7] Hereinafter, a seventh embodiment of the present invention will be described.

In the seventh embodiment, the electrode 2 on the substrate 3 in the liquid crystal display device according to the fourth embodiment (see FIG. 7) is
It is provided as shown in FIG. Here, FIG. 12A shows a plane view of the electrode structure of the liquid crystal display device, and FIG.
3A shows a cross section along AA ′ in FIG.

As shown, in the seventh embodiment, strip-shaped first metal electrodes 11 are arranged on the surface of the light-transmitting plastic substrate 3 at a period of 600 (μm). A strip-shaped second metal electrode 12 was periodically arranged at a position 1/6 of this cycle, and both were connected to an electrode wiring 93. Next, a strip-shaped fourth metal electrode 14 periodically arranged at a position 3/6 of the period and a strip-shaped fifth metal electrode periodically arranged at a position 4/6. Electrode 1
5 were both connected to the electrode wiring 93. Then, an insulating layer 34 made of silicon oxide is formed on this surface, and the third metal electrode 13 having a strip shape is formed at a position 2/6 of the period.
Are periodically arranged, connected to the electrode wiring 92, the strip-shaped sixth metal electrode 16 is periodically arranged at the position of ／, and connected to the electrode wiring 94.

Then, as shown in FIG.
AC power supplies 61, 6
2, 63 and 64 were connected and a voltage was applied to drive the liquid crystal display. At this time, the output voltage amplitudes of the AC power supplies 61, 62, 63 and 64 are set to 15 (V) and 45 (V), respectively.
(V), 30 (V), and 0 (V), the portion between the first metal electrode 11 and the second metal electrode 12 and the fourth metal electrode 14 and the fifth metal electrode 15 In the sandwiched portion, the reflectance of the light selectively reflected is represented by a curve 10B2 in FIG.
, The blue color is seen to be reflected, and the portion sandwiched between the second metal electrode 12 and the third metal electrode 13 and the portion sandwiched between the fifth metal electrode 15 and the sixth metal electrode 16 Since the reflectivity of the selectively reflected light is represented by the curve 10R2 in FIG. 4, red appears to be reflected, and the third metal electrode 13
4 and the portion between the sixth metal electrode 16 and the first metal electrode 11, the reflectance of the light selectively reflected is represented by a curve 10G2 in FIG. As a result, green was reflected. As a result, 300
Red, green, and blue were spatially repeated with a period of (μm). However, each of the AC power supplies 61, 62, 63 and 6
No. 4 has alternating voltage with the same polarity (positive / negative).

Similarly, AC power supplies 61, 62, 63
Output voltage amplitudes of 45 (V), 15
(V), 0 (V) and 30 (V), similarly,
Red, green, and blue appear to be spatially repeated periodically.

Similarly, AC power supplies 61, 62, 63
And 64 output voltage amplitudes of 30 (V), 45
(V), 15 (V), and 0 (V), the portions sandwiched between the first metal electrode 11 and the second metal electrode 12 and the fourth metal electrode 14 and the fifth metal electrode 15 In the sandwiched portion, the reflectance of the light selectively reflected is represented by a curve 10B2 in FIG.
, The blue color is seen to be reflected, and the portion sandwiched between the second metal electrode 12 and the third metal electrode 13 and the portion sandwiched between the fifth metal electrode 15 and the sixth metal electrode 16 Since the reflectivity of the selectively reflected light is represented by a curve 10G2 in FIG. 4, green appears to be reflected, and the third metal electrode 13
The reflectance of light selectively reflected at the portion between the fourth metal electrode 14 and the portion between the sixth metal electrode 16 and the first metal electrode 11 is represented by a curve 10R2 in FIG. Therefore, the red color was reflected. Accordingly, similarly, red, blue, and green appear to be spatially and periodically repeated.

The AC power supplies 61, 62, 63 and 6
4 is 45 (V), 30 (V), 0
Even if (V) and 15 (V) are set, similarly, red, blue, and green appear to be spatially periodically repeated.

As described above, according to the liquid crystal display device shown in FIG. 11, an extremely bright reflective RGB color filter can be realized.

Accordingly, as shown in FIG. 12, if a transmission type liquid crystal display device 22 capable of displaying gradations is laminated on the liquid crystal display device shown in FIG. 12, a liquid crystal display device capable of full color display is realized. can do.

In FIG. 12, reference numeral 22 denotes a liquid crystal display device capable of displaying a transmission type gradation using a polymer-dispersed liquid crystal in a guest-host mode, 221 denotes a row driving circuit, 222 denotes a column driving circuit, and 100 denotes each part. Is shown. Reference numeral 8 denotes a liquid crystal display device in which one cell has the structure shown in FIG.
Indicate the AC power supplies 61, 62, 63, 64 shown in FIG. Each pixel specified by a row and a column of the transmissive liquid crystal display device 22 is disposed so as to overlap each region between the electrodes of the liquid crystal display device 8.

In such a configuration, the control circuit 100
Controls the row drive circuit 221 and the column drive circuit 222 in accordance with RGB image data input from the outside to realize a transmittance pattern suitable for the display image pattern of the transmission type liquid crystal display device 22 and , AC power supplies 61, 62, 63, 6
As described above, full-color display with high light use efficiency is realized by applying a voltage to the liquid crystal display device 8 as described above.

In the present embodiment, the cycle of arranging the strip-shaped electrodes is set to 600 (μm). However, this value may be set arbitrarily, and depends on the processing accuracy of the electrodes and the definition of the display device. What is necessary is just to determine it. Further, the output voltage amplitude of each AC power supply is fixed, but the value may be any value as long as the central wavelength of selective reflection of the cholesteric liquid crystal composition can be modulated. Further, although the insulating layer 34 is formed of silicon oxide, any member may be used as long as it is a member that electrically insulates each electrode. For example, silicon nitride or an organic polymer may be used.

In the present embodiment, a guest-host mode polymer-dispersed liquid crystal is used for the transmission type monochromatic liquid crystal display device 22. However, as the transmission type monochromatic liquid crystal display device 22, a twisted nematic liquid crystal display device or a super A twisted nematic liquid crystal display, a cholesteric-nematic phase transition type guest-host mode liquid crystal display, a dynamic scattering mode liquid crystal display, and the like may be used. Further, a display device using an inorganic substance can be used as long as it is a transmission type single color display device.

Embodiment 8 Hereinafter, an eighth embodiment of the present invention will be described.

As shown in FIG. 15, in the eighth embodiment, the liquid crystal display device 8 of each embodiment described above has
The visible light absorbers 9 are stacked and arranged. Further, a number of optical fibers are bundled and bonded, and an optical fiber plate 21 cut in the diameter direction of the optical fibers and processed into a flat shape is stacked and arranged above the liquid crystal display device 8. It was done. The optical fiber plate 21 has a function of converting external light L0 incident from various directions into light L1 that travels substantially parallel to the normal direction of the optical fiber plate. The light enters the display surface almost perpendicularly and is selectively reflected. Then, the reflected light enters the optical fiber plate 21 again and passes therethrough. Thereby, the ratio of the light incident on the liquid crystal display device 8 blocked by the electrodes can be minimized, the viewing angle dependency of the liquid crystal display device 8 can be improved, and the light use efficiency can be further improved. And a bright liquid crystal display device can be realized.

In this embodiment, the optical fiber plate 21 is used as means for converting external light into substantially parallel light, but substantially the same effect can be obtained by using an optical system constituted by combining a plurality of lenses. be able to. Further, the material of the visible light absorber 9 is arbitrary, and one of a pair of substrates of the lowermost liquid crystal display device among the plurality of liquid crystal display devices stacked and arranged may be formed of the visible light absorber.

As described above, according to each embodiment of the present invention, the helical pitch of the cholesteric liquid crystal composition is changed without generating a domain boundary by an electric field substantially parallel to the surface of the substrate, and the reflected light and The wavelength dependence of transmitted light can be controlled with extremely high reflectance and transmittance.
In particular, it is possible to reduce the rate at which incident external light is blocked by the electrode, and to make it difficult for the rate at which light is blocked to change depending on the direction in which the display surface is viewed. Furthermore, a display in which the three primary colors of light are alternately reflected at high speed can be realized, or
A display in which the three primary colors of light are spatially repeated periodically can be realized. Furthermore, by utilizing this, the amount of light in a specific wavelength region can be arbitrarily controlled by stacking the transmission type monochromatic display devices. Therefore, a bright color liquid crystal display device with improved light use efficiency can be realized by the present invention.

The first, second, third, fourth, fifth
In the liquid crystal display device according to the embodiment, the transmission type monochromatic liquid crystal display device 22 capable of gradation display shown in the sixth and seventh embodiments is provided.
By controlling the amount of light of the liquid crystal display device in combination in the same manner, a wider variety of colors may be displayed.

[0102]

As described above, according to the present invention, it is possible to provide a reflection type color liquid crystal display device capable of performing bright color display.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a structure of a liquid crystal display device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing an angle difference φ between alignment azimuth angles of liquid crystal composition molecules according to a first example of the present invention.

FIG. 3 is a diagram showing a relationship between an electric field applied to a cholesteric liquid crystal composition and a spiral pitch of the cholesteric liquid crystal composition.

FIG. 4 is a diagram showing the wavelength dependence of the reflectance according to the first embodiment of the present invention.

FIG. 5 is a diagram showing the wavelength dependence of the transmittance according to the first embodiment of the present invention.

FIG. 6 is a diagram illustrating a cross section of a liquid crystal display device according to a second embodiment of the present invention.

FIG. 7 is a diagram illustrating a cross section of a liquid crystal display device according to a fourth embodiment of the present invention.

FIG. 8 is a diagram showing a cross section of a liquid crystal display device according to a fifth embodiment of the present invention.

FIG. 9 is a view showing a cross section of a liquid crystal display device according to a sixth embodiment of the present invention.

FIG. 10 is a diagram showing a cross section of another liquid crystal display device according to a sixth embodiment of the present invention.

FIG. 11 is a block diagram showing a configuration of a full-color liquid crystal display device according to a sixth embodiment of the present invention.

FIG. 12 is a view showing a structure of an electrode of a liquid crystal display according to a seventh embodiment of the present invention.

FIG. 13 is a diagram illustrating a connection relationship between electrodes and a power supply of a liquid crystal display device according to a seventh embodiment of the present invention.

FIG. 14 is a block diagram showing a configuration of a full-color liquid crystal display device according to a seventh embodiment of the present invention.

FIG. 15 is a view showing a cross section of another liquid crystal display device according to a sixth embodiment of the present invention.

[Explanation of symbols]

 1, 2, 11, 12, 13, 14, 15, 16 ... electrodes 91, 92, 93, 94 ... electrode wiring 3 ... substrate 34 insulating layer 4 ... alignment film 5, 5a, 5b ... cholesteric liquid crystal composition 6, 61 , 62, 63, 64: AC power supply 60: Switching element 7: Applied electric field

──────────────────────────────────────────────────続 き Continuing on the front page (72) Katsumi Kondo, Inventor 7-1-1, Omika-cho, Hitachi City, Ibaraki Prefecture Within Hitachi Research Laboratory, Hitachi, Ltd. (56) References JP-A-59-51328 (JP, A) JP-A-3-215831 (JP, A) JP-A-5-107521 (JP, A) JP-A-62-157342 (JP, A) JP-A-56-91277 (JP, A) (58) Int.Cl. ⁷ , DB name) G02F 1/1343

Claims (5)

(57) [Claims] 1. A cholesteric liquid crystal composition in which a pair of substrates opposed to each other at a predetermined interval and a gap between the pair of substrates is filled such that a helical axis is substantially perpendicular to both surfaces of the pair of substrates. And an electrode group provided on a surface of at least one of the pair of substrates on the other substrate side, wherein both surfaces of the pair of substrates on the other substrate side are the cholesteric liquid crystal. The orientation azimuth angle of the composition molecules is treated so as to be constant with respect to the surface, and the electrode group applies an electric field in a direction parallel to the surfaces of the pair of substrates to the cholesteric liquid crystal composition. Thus, the cholesteric liquid crystal composition is disposed on the surface of at least one of the pair of substrates on the other substrate side, and the helical pitch of the cholesteric liquid crystal composition is controlled by the electric field applied by the electrode group. The liquid crystal display device, characterized in that the. 2. The liquid crystal display according to claim 1, wherein the twist of the spiral is filled with a right-handed cholesteric liquid crystal composition, and the twist of the spiral is an average of the spontaneous pitch p0 of the spiral and the right-handed cholesteric liquid crystal composition. 2. The liquid crystal display according to claim 1, wherein a product of the refractive index n is equal to that of the liquid crystal display and the helical twist is filled with a left-handed cholesteric liquid crystal composition. A liquid crystal display device, wherein the substrates are stacked in parallel. 3. The liquid crystal display according to claim 1, wherein the product of the spontaneous spiral pitch p0 of the cholesteric liquid crystal composition and the average refractive index n satisfies the relationship of 380 (nm) ≦ n · p0 ≦ 530 (nm). 2. The liquid crystal display according to claim 1, wherein the product of the spontaneous spiral pitch p0 of the cholesteric liquid crystal composition and the average refractive index n satisfies a relationship of 480 (nm) ≦ n · p0 ≦ 630 (nm). 2. The liquid crystal display according to claim 1, wherein the product of the spontaneous pitch p0 of the helix of the liquid crystal composition and the average refractive index n satisfies a relationship of 570 (nm) ≦ n · p0 ≦ 800 (nm) Wherein each of the liquid crystal displays is stacked such that the substrates of each liquid crystal device are arranged in parallel in an arbitrary order, and the visible light absorber is a lower layer of all the stacked liquid crystal display devices. A liquid crystal display device, wherein: 4. The liquid crystal display according to claim 1, wherein the electrode group comprises: a first electrode group periodically arranged at regular intervals on the surface of the substrate; and a first electrode group. A second electrode group periodically arranged at a position shifted by 1/6 of the interval; and a position shifted by 2/6 of the interval in the same direction as the second electrode with respect to the first electrode group. A third electrode group periodically arranged at a distance of 3/6 of the distance from the first electrode group in the same direction as the second electrode with respect to the first electrode group. An electrode group; a fifth electrode group periodically arranged at a position shifted by 4/6 of the distance from the first electrode group in the same direction as the second electrode; A sixth electrode group periodically arranged at a position shifted by ５ of the distance in the same direction as the second electrode with respect to the group; The second electrode group is connected to a seventh electrode arranged at an arbitrary position, and the fourth electrode group and the fifth electrode group are connected to an eighth electrode arranged at an arbitrary position. A liquid crystal display characterized by being connected. 5. The liquid crystal display according to claim 4, wherein the cholesteric liquid crystal composition has a spontaneous spiral pitch p0.
A liquid crystal display characterized by satisfying the following relationship: 380 (nm) ≦ n · p0 ≦ 530 (nm).