JP2813222B2 - Liquid crystal display device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and in particular, to a DAP (Deformation of Vertically Alignment) utilizing an electric field control birefringence effect.
ed Phase) liquid crystal display device.

[Conventional technology]

As a liquid crystal display element, a TN (Twisted Nematic) type liquid crystal display element is well known, but since the TN type liquid crystal display element is a black-and-white display and has a simple configuration, it is mainly used for a display section of a clock or a calculator. Widely used. However, TN
When using a liquid crystal display device as an optical shutter,
Because of optical rotation dispersion, perfect black cannot be obtained, and therefore, when a color liquid crystal display element is manufactured in combination with a color filter, there is a problem that sufficient color reproducibility cannot be obtained. Further, since the steepness of the threshold voltage characteristic of the voltage transmittance characteristic is poor, there is a problem that the time division driving characteristic is poor and it is difficult to display a large capacity.

On the other hand, as a liquid crystal display element capable of multicolor display,
2. Description of the Related Art A DAP type liquid crystal display element of a type that modulates light by changing the birefringence of a liquid crystal layer by applying a voltage by utilizing an electric field control birefringence effect of liquid crystal is known. This DAP type liquid crystal display element is a display element of a display method that has been known for a long time, has an excellent feature that a complete optical shutter effect can be obtained, and a black and white display can be made depending on a liquid crystal cell condition setting. It has the feature that multicolor display using refraction colors is also possible.

The following describes the structure and principle of the DAP type liquid crystal display element.
This will be described with reference to the drawings.

FIG. 5 is a sectional view showing a basic configuration of a DAP type liquid crystal display device. As shown in the figure, a liquid crystal layer 3 made of a liquid crystal composition having a negative dielectric anisotropy is provided between a pair of translucent substrates 11 and 21 made of glass or plastic having transparent electrodes 12 and 22. The outer periphery of the seal 1 is also used as a spacer.
The liquid crystal cells of the DAP type liquid crystal display device are formed by sealing with 4,24. The substrates 11 and 21 of this liquid crystal cell and the transparent electrode 1
Alignment films 15 and 25 are formed on the sides in contact with the liquid crystals 2 and 22 so as to vertically align the liquid crystal with respect to the substrate. Also,
Outside the liquid crystal cell, a pair of polarizing plates 16 and 2
6, a liquid crystal cell and a pair of polarizers constitute a DAP type liquid crystal display element.

In a DAP type liquid crystal display device having such a configuration, when no voltage is applied, the liquid crystal is oriented perpendicular to the substrates 11 and 21.
When the polarization axes of 16 and 26 are perpendicular to each other, a black display is obtained. When a voltage is applied to the upper and lower transparent electrodes 12 and 22,
The liquid crystal molecules are tilted with respect to the substrates 11 and 21 as shown in FIG. 6 (b), and birefringence occurs when the tilt direction is other than parallel or orthogonal to the transmission axes or absorption axes of the polarizing plates 16 and 26. Transmits light. The spectral spectrum of the transmitted light corresponds to the retardation, and white or colored display can be performed by adjusting the thickness of the liquid crystal layer 3, the birefringence of the liquid crystal, and the applied voltage.

As described above, the DAP type liquid crystal display element has a feature that a large capacity display is possible, and further, a monochrome display and a multicolor display can be performed without using a color filter depending on the setting of cell conditions. I have.

However, this DAP type liquid crystal display element has a disadvantage that the viewing angle is narrow. That is, since the above-described liquid crystal layer is optically regarded as a uniaxial crystal, the birefringence greatly changes depending on the viewing angle. For this reason, when no voltage is applied or when an effective value voltage equal to or lower than the threshold voltage is applied, light leakage occurs when black is obtained when viewed from the front, but when viewed obliquely.

Therefore, in order to improve the above-mentioned disadvantages of the DAP type liquid crystal display element, a method has been proposed in which an optically negative uniaxial polymer film is laminated as a birefringent layer on the DAP type liquid crystal cell to improve the viewing angle dependency. (JP-A-62-210423).

[Problems to be solved by the invention]

By the way, in order to obtain a uniform display in the DAP type liquid crystal display device, it is necessary to control the direction in which the liquid crystal tilts when a voltage is applied. For this reason, it is necessary to perform alignment control in which the alignment of liquid crystal molecules when no voltage is applied is tilted by θ ° from the vertical direction as shown in FIG. If the tilt angle θ ° is small, the direction in which the liquid crystal tilts when a voltage is applied becomes non-uniform, causing display unevenness due to an alignment defect called reverse tilt, which causes a problem that the contrast is reduced. Also, the pretilt angle θ
When the angle is increased, the above-mentioned alignment defect does not occur, but there is a problem that the viewing angle becomes narrow and display performance is impaired. Therefore, the preferable tilt angle θ ° is 1 ° to 3 °, and the liquid crystal molecules are tilted in the pretilt direction by applying a voltage as shown in FIG. 6 (b).

However, in the method described in the above publication, there is no pretilt, and it is certainly effective when the liquid crystal is perfectly vertically aligned, but when the liquid crystal molecules have the pretilt, or the most contrast can be obtained at the viewing position. When a voltage is applied to the liquid crystal to give a tilt angle to the liquid crystal, an appropriate compensation condition cannot be obtained, and there is a problem that a viewing angle becomes narrow and a contrast is lowered. In addition, the method described in the above publication has the following problems, and no good characteristics can be obtained.

1) In a stretched film, birefringence is likely to occur in the film plane, so that the direction in which viewing angle can be compensated is limited.

2) With the polymer described in the publication, it is necessary to perform very special molding, so that it is difficult to produce a uniform film, and the productivity is low.

The present invention has been made in order to solve the above-described problems, and has a significantly small viewing angle dependency of display characteristics, a high contrast, and a high contrast even when the viewing position is shifted from the front of the element. It is an object of the present invention to provide a DAP type liquid crystal display device having a high DAP type.

[Means and actions for solving the problem]

In order to achieve the above object, the present invention provides a liquid crystal cell including a pair of substrates having electrodes, a liquid crystal layer sealed between the substrates and vertically aligned with respect to the substrate when no voltage is applied, and a liquid crystal cell. A pair of polarizing plates sandwiched from the outside, a cholesteric liquid crystal layer provided between the polarizing plate on one side and the liquid crystal cell and having a product of a helical pitch and a refractive index of 400 nm or less, or a fixed orientation. In a liquid crystal display device composed of a cholesteric liquid crystal polymer layer and a cholesteric liquid crystal layer or a helical structure of a helical structure of the cholesteric liquid crystal polymer layer, the helical axis is tilted in the same direction as the tilt direction of liquid crystal surface molecules. Features.

Hereinafter, the configuration and operation of the liquid crystal display device according to the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a first configuration example of a liquid crystal display device according to the present invention.

As shown in FIG. 1, the liquid crystal display device of the present invention has a negative dielectric anisotropy between a pair of light-transmitting substrates 11 and 21 having transparent electrodes 12 and 22 such as glass and plastic. A liquid crystal layer 3 composed of a nematic liquid crystal composition is formed, and the liquid crystal layer 3 is formed by outer peripheral seals 14 and 24 which also serve as spacers.
Is sealed to form a liquid crystal cell 4. On the sides of the substrates 11 and 21 and the transparent electrodes 12 and 22 that are in contact with the liquid crystal, alignment films 15 and 25 are formed so that the liquid crystal is tilted and vertically aligned with respect to the substrate. A pair of polarizing plates 1 is provided outside the liquid crystal cell 4.
6, 26 are arranged so as to sandwich the liquid crystal cell.

A cholesteric liquid crystal layer 37 is provided between one side of the polarizing plates 16 and 26 and the liquid crystal cell 4, more specifically, between the upper substrate 21 of the liquid crystal cell 4 and the upper polarizing plate 26 in the drawing. Is provided, and the cholesteric liquid crystal layer 37 is a pair of substrates.
It is formed between 31,41. Reference numerals 34 and 44 are outer peripheral seals that also serve as spacers. Also, the substrate on the liquid crystal cell 4 side
31 can be omitted. The above cholesteric liquid crystal layer
In 37, the helical axis of the cholesteric helical structure is tilted in the same direction as the tilt direction of the liquid crystal molecules of the liquid crystal layer 3, as shown in FIG.

The cholesteric liquid crystal layer 37 oriented as described above is considered to be substantially isotropic with respect to light traveling in the helical axis direction, and the refractive index in the helical axis direction is smaller than the refractive index in the direction perpendicular to the helical axis. There is. Therefore, as shown in FIG. 1, by disposing the cholesteric liquid crystal layer 37 between the conventional DAP type liquid crystal cell 4 and the polarizing plate 26, the viewing angle dependence of the display characteristics of the liquid crystal display element can be significantly reduced. it can.

In order for the cholesteric liquid crystal layer used in the present invention to exhibit the above-mentioned excellent characteristics, the pitch of the cholesteric helical structure must be about the wavelength of visible light (400 to 800 nm).
m), and just like this, the product of the index of refraction and the pitch of the liquid crystal must be less than 400 nm to prevent coloring due to selective reflection (or transmission) by the helical structure. It is.

Further, the present invention is characterized in that the helical pitch of the cholesteric liquid crystal is inclined in a direction in which the liquid crystal molecules of the operation cell are inclined.

As described above, in the DAP-type liquid crystal display device, in order to obtain a uniform display, the orientation when no voltage is applied is not completely vertical orientation, but from the vertical direction as shown in FIG. 6 (a). θ ₀ (this angle is referred to as a pretilt angle). Generally this pretilt angle is 1 °
From 3 °.

In the present invention, for example, the helical axis of the cholesteric liquid crystal is tilted by the same θ ₀ as the pretilt angle of the DAP type liquid crystal cell as shown in FIG. DAP-type liquid crystal display devices provide the highest contrast when observed from the tilted direction of the liquid crystal.However, by aligning the cholesteric liquid crystal in this way, ideal compensation conditions can be obtained without any loss of contrast. Can be realized.

Further, it is possible to perform the viewing angle compensation even in the case of a pretilt angle of 3 degrees or more, which has not been conventionally adopted due to the problem of the viewing angle.

Here, FIG. 3 shows another example of how the helical axis of the cholesteric liquid crystal compensator according to the present invention is inclined.
This is to improve the viewing angle during time division driving. At the time of the time-division driving, the liquid crystal molecules of the DAP liquid crystal cell on the operation side receive a non-selection voltage even at the non-selection point, and the tilt angle of the liquid crystal becomes larger than the pretilt angle. This angle varies greatly depending on the voltage value, but is generally between 3 ° and 20 °. In this example, the tilt angle θ when a non-selection voltage is applied
By making the inclination angle of the helical axis of the cholesteric liquid crystal compensator equal to that of the cholesteric liquid crystal compensator, ideal compensation conditions can be realized without any loss of contrast.

When the viewing direction of the observer is determined with respect to the display element (for example, an instrument panel of an automobile), the helical axis is directed to the viewing direction, and the applied voltage or the pretilt angle of the DAP liquid crystal cell is adjusted. Thereby, an optimum viewing angle and a high contrast can be obtained.

Incidentally, in order to control the inclination angle of the helical axis of the cholesteric liquid crystal, a conventional method used for a nematic liquid crystal can be used. For example, a method in which a polymer film such as polyimide or polyamide is formed on a substrate and rubbed, a method of obliquely depositing SiO, a method of obliquely depositing SiO, and then treating with a vertical alignment agent can be exemplified. .
As shown in FIG. 3, by giving a tilt angle of the liquid crystal molecules of φ to the substrate interface by these methods, a tilt angle of about ψ (= ψ = 90 ° −φ) can be given to the helical axis. . The preferable range of the tilt angle varies depending on the method of use as described above, but is approximately 1 ° to 30 °.
° is preferred.

Next, FIG. 4 shows a second configuration example of the liquid crystal display device according to the present invention.

In the liquid crystal display element shown in FIG. 4, the configuration of the liquid crystal cell 4 is the same as that of the first configuration example shown in FIG. In this example, the cholesteric liquid crystal polymer 57 fixed in orientation is used as the compensator. The cholesteric liquid crystalline polymer 57 is made of a transparent substrate 51 such as glass or plastic.
It is provided between the liquid crystal cell 4 and one of the polarizing plates 16 or 26 (the upper polarizing plate 26 in the illustrated example). The substrate 51 is omitted and the substrate 21 on the liquid crystal cell 4 side is omitted.
A cholesteric liquid crystalline polymer film can also be provided directly on top. As in the first configuration example, it is also possible to sandwich a cholesteric liquid crystal polymer film between a pair of substrates. In the cholesteric liquid crystal polymer layer 57 having the alignment fixed, the helical axis of the cholesteric helical structure is tilted in the same direction as the tilt direction of the liquid crystal molecules of the liquid crystal layer 3 on the liquid crystal cell 4 side.

The alignment-fixed cholesteric liquid crystalline polymer is a polymer compound exhibiting thermotropic liquid crystallinity,
It is obtained by orienting at a temperature at which a cholesteric liquid crystal is exhibited, and then cooling to a temperature lower than the glass transition point, and the cholesteric twist alignment in the liquid crystal phase is maintained even in the solid phase. It can also be produced by distilling off the solvent from a lyotropic liquid crystalline polymer concentration solution.

This cholesteric liquid crystalline polymer optically exhibits exactly the same characteristics as the low-molecular cholesteric liquid crystal described above. Therefore, by stacking it on a liquid crystal cell of a general DAP type liquid crystal display device, the viewing angle of the display characteristics of the display device is increased. Dependencies can be reduced very effectively. Further, in the liquid crystal display element according to the present invention, the helical pitch of the cholesteric liquid crystalline polymer having the orientation fixed is inclined in the direction in which the liquid crystal molecules of the operation cell are inclined. Similarly to the above, the visual angle compensation can be performed even when the DAP liquid crystal cell 4 to be operated has a pretilt angle or when the pretilt angle is 3 degrees or more which has not been adopted due to the problem of the viewing angle. Also,
Since the viewing angle compensation at the time-division driving can be performed more completely, a liquid crystal display device having a high contrast and a wide viewing angle can be obtained. In addition, when the viewing direction of the observer is determined with respect to the liquid crystal display element (for example, an instrument panel of an automobile), an optimum viewing angle and high contrast can be obtained similarly.

In addition, in addition to these, the liquid crystal polymer 57 having the fixed orientation has a high self-holding property by itself, and thus can be formed on the single substrate 51 as in this example. The feature is that the configuration can be simplified. Also,
Since the compensator using the liquid crystalline polymer 57 with the alignment fixed is all made of solid, it is resistant to environmental changes and external forces, and has high reliability. Further, it has a feature that the performance of the compensator hardly changes in temperature.

Incidentally, in order to control the inclination angle of the helical axis of the cholesteric liquid crystalline polymer, a conventional method used for a nematic liquid crystal can be used. For example, a method in which a polymer film such as polyimide or polyamide is formed on a substrate and rubbed, a method of obliquely depositing SiO, a method of obliquely depositing SiO, and then treating with a vertical alignment agent can be exemplified. . Then, a cholesteric liquid crystalline polymer film is applied on the substrate treated by these methods, and is oriented in a liquid crystal state. Then, the orientation is fixed by the method described above. Well, the third
As in the case of the alignment treatment according to the first configuration example shown in the figure, by giving the inclination angle of the liquid crystal molecules of φ to the substrate interface by these methods, the helical axis becomes approximately ψ.
(Ψ = 90 ° −φ). The preferred range of the tilt angle varies depending on the manner of use as described above, but is preferably in the range of approximately 1 ° to 30 °.

In the liquid crystal display device of the present invention, the transmission axes of the polarizing plates 16 and 26 disposed above and below the liquid crystal cell 4
The direction of the pretilt of liquid crystal molecules on 1 and 12 (the direction of alignment of liquid crystal molecules onto the substrate) and approximately 30 ° to 60 °
It is preferable to provide them at an angle.

〔Example〕

Next, specific examples of the liquid crystal display device according to the present invention will be described.

Embodiment 1. First, an operation cell is manufactured as follows.

Two glass substrates having transparent electrodes made of ITO (Indium Tin Oxide) are prepared, and a vertical alignment agent FC805 manufactured by 3M is spin-coated on each substrate, baked, and then rubbed with a cotton cloth. After the above processing, both substrates are bonded together via a spacer such that the alignment film surfaces face each other and the rubbing directions are antiparallel. Then, a liquid crystal composition EN37 manufactured by Chisso Corporation having a negative dielectric anisotropy was injected into a gap between the two substrates to produce a driving DAP type liquid crystal cell. The thickness of the liquid crystal layer of this liquid crystal cell is 7.5 μm. The pretilt angle was θ ₀ = 2 °.

In addition, if a pair of unitary gray linear polarizing plates are arranged above and below this liquid crystal cell so that their polarization axes are orthogonal to each other and form an angle of 45 ° with the rubbing direction, a normal DAP type liquid crystal display device can be obtained. Be composed.

 Next, a compensation cell is manufactured as follows.

A PIQ manufactured by Hitachi Chemical Co., Ltd. is used as an aligning agent, which is spin-coated on a glass substrate, baked at 300 ° C., and rubbed with a cotton cloth. The same processing is performed on another substrate, and the two substrates are bonded together via a spacer such that the alignment film surfaces face each other and the rubbing directions are antiparallel. A cholesteric liquid crystal (BDH) having a product of the pitch and the refractive index at room temperature of 350 nm is provided in a gap between the two substrates.
A liquid crystal (mixed liquid crystal of TM736 and CB15 manufactured by Sharp Corporation) was injected to prepare a compensation cell. The thickness of the cholesteric liquid crystal layer of the compensation cell is 10 μm. The pretilt angle of the liquid crystal molecules was ψ = 2 °.

Next, the operation cell and the compensation cell manufactured as described above are overlapped, and a pair of neutral gray linear polarizing plates are vertically arranged so as to sandwich the two cells, the polarization axes of which are orthogonal to each other. And a rubbing direction at an angle of 45 ° to produce a liquid crystal display device.

The rubbing directions of the two cells on the adjacent substrates were antiparallel, whereby the direction of the pretilt of the operating cell and the direction of inclination of the helical axis of the cholesteric liquid crystal were matched.

The liquid crystal display device thus manufactured was black when no voltage was applied, and became colorless when a voltage of 2.8 V was applied. When the viewing angle at the time of voltage application was compared with the element without the compensation cell, the liquid crystal display element of this example had less change in color and brightness, and the liquid crystal display element of this example had excellent display performance. It was confirmed that. In addition, it was confirmed that even in the static drive of 3V and the time division drive of 1/64 duty, the display performance was excellent as compared with the element without the compensation cell.

Example 2 First, a liquid crystal cell similar to that of Example 1 was prepared as an operation cell except that the pretilt angle was 1 °.

Next, as a compensating cell, a compensating cell in which the pretilt angle of the liquid crystal molecules is ψ = 5 ° was prepared in the same manner as in Example 1 by using LQ1800 manufactured by Hitachi Chemical Co., Ltd. as an aligning agent. After stacking in the same manner as in Example 1, a pair of polarizing plates was provided, and a liquid crystal display element was manufactured.

This liquid crystal display element was subjected to 1/64 duty time division driving and compared with an element without a compensation cell under the condition that an effective value voltage of 2.5 V was applied to a non-selected point. The device showed less change in color and brightness, and it was confirmed that the liquid crystal display device of this example had excellent display performance.

Example 3 First, a liquid crystal cell similar to that of Example 1 was prepared except that the pretilt angle was 1 ° as an operation cell.

Next, as the compensating cell, a cell in which the pretilt angle of the liquid crystal molecules was ψ = 15 ° was manufactured in the same manner as in Example 1 by using an oblique deposition method of SiO for the alignment treatment. After laminating in the same manner as described above, a pair of polarizing plates was provided to produce a liquid crystal display device.

This liquid crystal display element was subjected to 1/64 duty time division driving, observed from a direction of 15 ° from the substrate normal, and the applied voltage was adjusted so that the contrast became maximum. When compared with the element without the compensation cell under these conditions, the liquid crystal display element of the present example had a wide viewing angle centered on the viewing direction, whereas in the case without the compensation cell, Sufficient contrast was not obtained in the viewing direction.

Example 4 First, a liquid crystal cell similar to that of Example 1 was prepared as an operation cell except that the pretilt angle was 1 °.

Next, LQ manufactured by Hitachi Chemical Co., Ltd. was used as an alignment film on a glass substrate.
After rubbing with cotton cloth, the liquid crystal polymer represented by the following structural formula was placed on the rubbing surface while heating the substrate to about 300 ° C. with a hot plate, and-(-O-Ph- _{Ph-OCO- (CH 2) 8} -C (O)) 0.4 - - (- O-Ph-Ph-OCO-CH 2 -CH (CH 3) - (CH 2) 2 -
C (O) _0.6 ^- (Ph is a phenylene group) The liquid crystalline polymer is applied to the substrate surface extending in the blade where the molten. Thereafter, the temperature was lowered to about 250 ° C. to obtain a cholesteric phase, and the temperature was maintained for about 30 minutes. Next, this sample was quenched to room temperature to prepare a compensator made of a liquid crystalline polymer whose orientation was fixed.

It was confirmed from the viewing angle dependence of the selective reflection spectrum that the cholesteric pitch of this compensator was about 360 nm and the helical axis of the liquid crystalline polymer was inclined from the normal of about 5 °.

Next, after the operation cell and the compensator were laminated in the same manner as in Example 1, a pair of polarizing plates was disposed above and below, thereby producing a liquid crystal display device.

This liquid crystal display element was subjected to 1/64 duty time division driving and compared with an element without a compensation cell under the condition that an effective value voltage of 2.5 V was applied to a non-selected point. The device showed less change in color and brightness, and it was confirmed that the liquid crystal display device of this example had excellent display performance.

〔The invention's effect〕

As described above, according to the present invention, a cholesteric liquid crystal layer having a helical axis inclined in the pretilt direction of a liquid crystal cell or a cholesteric liquid crystal having a fixed orientation is provided between a polarizing plate of a DAP type liquid crystal display device and a liquid crystal cell. By providing the conductive polymer layer, the viewing angle dependence of the display characteristics of the DAP type liquid crystal display device can be effectively reduced, and a liquid crystal display device having a wide viewing angle and high contrast can be provided.

Further, according to the present invention, as a result of tilting the helical axis in the direction of the pretilt of the liquid crystal cell, if the liquid crystal of the DAP type liquid crystal has a pretilt angle or if the viewing position is shifted from the front of the element, time division is performed. Even in the case of driving, a liquid crystal display device having high contrast and a wide viewing angle can be provided.

Furthermore, in the liquid crystal display device of the present invention, when a cholesteric liquid crystal polymer having a fixed orientation is used as a compensating plate, the compensating plate can be formed on a single substrate. Can be simplified. Further, since the compensator using the cholesteric liquid crystalline polymer is all solid, it is resistant to environmental changes and external forces, and has high reliability. Furthermore, it has the characteristic that the compensator performance hardly changes with temperature, and is extremely valuable industrially.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a first configuration example of a liquid crystal display device according to the present invention, and FIGS. 2 and 3 show liquid crystal layers of the liquid crystal display device and the cholesteric liquid crystal layer of the configuration shown in FIG. FIG. 4 is an explanatory view of an alignment state, FIG. 4 is a cross-sectional view showing a second configuration example of a liquid crystal display device according to the present invention, FIG. 5 is a cross-sectional view showing an example of a basic configuration of a DAP type liquid crystal display device, and FIG. FIG. 6 is an explanatory diagram of an alignment state of liquid crystal molecules of the liquid crystal display device having the configuration shown in FIG. 3: Liquid crystal layer, 4: Liquid crystal cell, 11, 21, 31, 41, 51: translucent substrate, 12, 22, transparent electrode, 15, 25: alignment film, 16, 26: polarizing plate, 37: cholesteric liquid crystal Layer, 57 ... Cholesteric liquid crystalline polymer layer.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-60-256121 (JP, A) JP-A-1-270024 (JP, A) JP-A-62-210423 (JP, A) 98417 (JP, U) (58) Field surveyed (Int. Cl. ⁶ , DB name) G02F 1/1337 G02F 1/1347

Claims (1)

(57) [Claims] 1. A liquid crystal cell having a pair of substrates having electrodes, a liquid crystal layer sealed between the substrates and vertically inclined with respect to the substrate when no voltage is applied, and disposed so as to sandwich the liquid crystal cell from outside. A cholesteric liquid crystal layer or a cholesteric liquid crystal polymer layer having a fixed orientation, wherein the product of the helical pitch and the refractive index is 400 nm or less, which is provided between the pair of polarizing plates and the polarizing plate on one side and the liquid crystal cell. Wherein the helical axis of the helical structure of the cholesteric liquid crystal layer or the cholesteric liquid crystalline polymer layer is tilted in the same direction as the tilt direction of the liquid crystal molecules.