JPH05215912A - Liquid crystal display element - Google Patents

Abstract

PURPOSE:To enhance visual angle characteristics by using a high polymer film which is a negative optical anisotropic body having an optical axis in the nor mal line direction of a liquid crystal cell substrate. CONSTITUTION:A pair of polarized plates 1, 5 is arranged at both sides by holding it between a liquid crystal cell 3 clamping a nematic liquid crystal which has a positive dielectric anisotropic property between a pair of substrates 6,7 and a sheet of high polymer film 2. Here the high polymer film 2 is the negative optical isotropic body having an optical axis in the normal line directions of the liquid crystal cell substrates 6, 7 and has an ellipse 31 of refractive index. Namely a refractive index nz in the normal line direction of the film surface 32 and refractive indexes nx, ny of two directions which are vertical to it and mutually orthogonally crossed, have a shape of a dis wid shape which is in a relation of nz<nx=ny. The product of (nx-nz) of the high polymer 2 and a thickness of the film is preferred to be equal to the product of the double refraction of the liquid crystal cell 3 and the cell gap, or to be less than it.

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.

[0002]

2. Description of the Related Art A liquid crystal display device of active matrix type in which a TFT or an MIM device is provided in each pixel has come to be able to produce a large display of 14 to 17 inches due to technological progress in the last few years. T
Application to V is expected. However, as the screen becomes larger, the dissatisfaction with the display performance, especially the viewing angle characteristics, is increasing. The cause is mainly in a liquid crystal display mode itself called a twisted nematic (hereinafter referred to as TN) which has been adopted in a conventional liquid crystal display element.

As shown in FIG. 14, the conventional TN type liquid crystal display device includes an upper polarizing plate 1, a liquid crystal cell 3, a lower polarizing plate 5,
The liquid crystal cell includes an upper substrate 6, a lower substrate 7, a transparent electrode 8 and a nematic liquid crystal 9. As for the relationship between the respective axes, as shown in FIG. 9, the direction of the polarization axis of the upper polarizing plate 1 (hereinafter, the polarization axis will be referred to as the transmission axis) is 11, and the direction of the liquid crystal alignment of the upper substrate 6 of the liquid crystal cell is 12. The liquid crystal alignment direction of the lower substrate 7 of the liquid crystal cell is 13, and the polarization axis direction of the lower polarizing plate 5 is 14, 11.
The angle formed by 2 is 21, the twist angle of the nematic liquid crystal 9 determined by 12 and 13 is 22, and the angle formed by 14 is 13 is 23.
Then, the angle 21 and the angle 23 are set to about 0 degree, and the angle 22 is set to about 90 degree.

At this time, the conventional TN type liquid crystal display device is shown in FIG.
The voltage transmittance characteristics shown in are shown.

[0005]

However, the conventional TN type liquid crystal display device having the above structure has a problem that the viewing angle range in which the display can be satisfactorily recognized is narrow. FIG. 15 shows the viewing angle characteristics when the conventional TN type liquid crystal display device is driven with 5 V applied to the ON state and 1 V applied to the OFF state. Here, the center of the figure is the substrate normal direction, and the six concentric circles surrounding it are the inclination angles from the normal direction in the order of 10 °, 20 °, 30 °, 40 °, 50 from the inside.
The direction of 60 degrees is shown. Also 41, 42, 4
3, 44, 45, and 46 have a contrast ratio of 1:
1, 1: 3, 1:10, 1:30, 1: 100, 1: 3
00 is an isocontrast curve. Thus, the conventional T
The characteristics of the N-type liquid crystal change greatly depending on the viewing angle.
Although it cannot be read from this figure, when viewed from above, the troublesome phenomenon of inversion occurs. The inversion phenomenon is a phenomenon in which the transmittance becomes dark and then bright again as the voltage rises, so that when a halftone is displayed, a portion to be displayed darker becomes brighter.

The present invention solves such a problem, and an object thereof is to provide a liquid crystal display device having excellent viewing angle characteristics by using a polymer film as a viewing angle compensating plate.

[0007]

A liquid crystal display device of the present invention comprises a liquid crystal cell in which a nematic liquid crystal having a positive dielectric anisotropy is sandwiched between a pair of substrates, and at least one polymer film. In a liquid crystal display device comprising a pair of polarizing plates arranged on both sides of them, the polymer film is a negative optical anisotropic body having an optical axis in the direction normal to the liquid crystal cell substrate. Characterize.

Further, a liquid crystal cell in which a nematic liquid crystal having a positive dielectric anisotropy is sandwiched between a pair of substrates, at least one polymer film, and a pair of polarized lights arranged on both sides sandwiching them. In a liquid crystal display device including a plate, the polymer film is a negative optical anisotropic body having an optical axis in a direction substantially parallel to the average direction of the liquid crystal director when an on-voltage is applied. ..

Further, the twist angle of the liquid crystal of the liquid crystal cell is about 90 degrees.

Further, the transmission axes of the polarizing plates are adjacent to each other,
Alternatively, it is characterized in that it is arranged so as to be perpendicular to the alignment treatment direction of the adjacent liquid crystal cell substrates with the polymer film interposed therebetween.

Further, the twist angle of the liquid crystal of the liquid crystal cell is about 0 degree.

Further, the liquid crystal display element is characterized by performing bright display when no voltage is applied and dark display when voltage is applied.

The pretilt angle of the liquid crystal is 5 degrees or more.

The anchoring energy between at least one substrate of the liquid crystal cell and the liquid crystal is 1 × 10 ^-4.
It is characterized in that it is J / m ² or less.

Further, when the liquid crystal cell is driven, the effective voltage at the time of turning on is set to four times or more the threshold voltage of the liquid crystal cell.

The polymer films are arranged above and below the liquid crystal cell. In addition, the sum of the values of (n _x −n _z ) × d of the polymer film is Δn of the liquid crystal cell.
It is characterized in that it is equal to or smaller than the value of xd.

Further, the wavelength dispersion value ν of Δn of the polymer film is smaller than that of the liquid crystal.

[0018]

【Example】

(Example 1) As shown in FIG. 1, the liquid crystal display element in Example 1 of the present invention comprises an upper polarizing plate 1, a polymer film 2, a liquid crystal cell 3, a lower polarizing plate 5, and an upper substrate 6 of the liquid crystal cell. ,
It is composed of a lower substrate 7, a transparent electrode 8 and a nematic liquid crystal 9. As shown in FIG. 2, the relationship between the respective axes is such that the polarization axis (absorption axis) direction of the upper polarizing plate 1 is 11, the liquid crystal alignment direction of the upper substrate 6 of the liquid crystal cell is 12, and the liquid crystal of the lower substrate 7 of the liquid crystal cell. The alignment direction is 13, and the polarization axis directions of the lower polarizing plate 5 are 14, 11
When the angle made by 12 is 21, the twist angle of the nematic liquid crystal 9 determined by 12 and 13 is 22, and the angle made by 14 is 13, the angles 21 and 23 are 90 degrees, and the angle 22 is 90 degrees. Set to.

The nematic liquid crystal 9 includes liquid crystal ZLI-4393 manufactured by Merck and chiral dopant C manufactured by BDH.
B-15 was used by adding 0.1 wt%. ZLI-43
Since the birefringence Δn of 93 is 0.0851 and the cell gap d is 4.7 μm, Δn × d is 0.40 μm. The liquid crystal uses a polyimide alignment film with a pretilt angle of 1
Homogeneous orientation was performed at a temperature of less than 100 degrees. On the other hand, the polymer film 2 is a negative optical anisotropic body made of polycarbonate and has a refractive index ellipsoid as schematically shown in FIG. That is, if the refractive index in the normal direction of the film surface 32 is n _z and the refractive indices in two directions perpendicular to this are n _x and n _y , then n
having stones-like shape having a relationship of _z <n _x = n _y. The film used here is n _x = 1.588, n _y = 1.58.
8, n _z = 1.585, film thickness d = 100 μm, and (n _x −n _z ) × d = 0.3 μm, Δn of the liquid crystal cell
It was set to be slightly smaller than xd.

FIG. 4 shows the voltage transmittance characteristics of the liquid crystal display element in Example 1 of the present invention produced as described above. White when no voltage is applied, and black when voltage is applied,
It is a so-called normally white display. The threshold voltage defined by the voltage at which the transmittance changes by 10% is 1.
It is 45 volts.

FIG. 5 shows the viewing angle characteristics when the liquid crystal cell is driven with the state of applying 7 V applied to the on state and the state of applying 1 V applied to the off state. If only 5 V is applied to obtain contrast, it is sufficient to apply 5 V, but by applying 7 V, the liquid crystal rises almost vertically to the substrate, and the viewing angle compensation by the polymer film becomes more effective. When this viewing angle characteristic is compared with the viewing angle characteristic of the conventional TN type liquid crystal shown in FIG. 15, it can be seen that the uniform contrast curve 44 of 1:30 spreads ± 20 degrees or more to the left and right. The vertical direction is not too narrow as in the conventional case, and shows well-balanced characteristics. Also, although it cannot be read from this figure, halftone reversal was less likely to occur.

(Embodiment 2) The cell structure, axial relationship, etc. of Embodiment 2 are the same as those of Embodiment 1 shown in FIGS. 1 and 2, except that the pretilt angle of liquid crystal molecules is set to 10 degrees. different. As the pretilt angle becomes higher, the threshold voltage becomes 0.
Even if the voltage applied was reduced by 3 volts and the ON applied voltage was 6 volts, a wide viewing angle equivalent to that in Example 1 could be obtained.

Conventionally, the TN type liquid crystal has a pretilt angle of 5 degrees or less. However, when a visual angle compensating plate is provided, it is advantageous to set a large pretilt angle in order to widen the visual angle.

(Embodiment 3) The cell structure, axial relationship and the like of Embodiment 3 are the same as those of Embodiment 1 shown in FIGS. 1 and 2, except that an oblique vapor deposition film of SiO is used as an alignment film. Is different.
As a result, the anchoring energies of the liquid crystal molecules and the alignment film became about 4 × 10 ⁻⁵ J / m ² . This is a very small value as compared with the value of 1 × 10 ⁻³ J / m ² or more when a normal polyimide or polyvinyl alcohol is used as the alignment film. The liquid crystal molecules in the vicinity of the substrate usually do not move unless a considerably high voltage is applied, but when the anchoring energy is about 4 × 10 ⁻⁵ J / m ² , they start to move at only a few volts. Therefore, in the first embodiment, the ON applied voltage is set to 7 volts, but in the third embodiment, the same wide viewing angle can be obtained with only 5.5 volts. As a method for reducing the anchoring energy, other known methods include using an LB film as an alignment film and directly rubbing the surface of the transparent electrode, and these also have an effect corresponding to the anchoring energy.

(Embodiment 4) The cell structure, axial relationship, etc. of Embodiment 4 are the same as those of Embodiment 1 shown in FIGS. 1 and 2, but a high refractive index ellipse having a shape as shown in FIG. 3 as a polymer film. The difference is that a shape as shown in FIG. 6 is adopted instead of the body.
It is still negative optical anisotropic body made of polycarbonate, but the relationship of n _z <n _x = n _y are the same, the optical axis is inclined 5 degrees from the normal direction of the film plane 32, when voltage is applied It is almost parallel to the average direction of the liquid crystal director of the liquid crystal cell. Since the liquid crystal of the liquid crystal cell does not completely rise at a voltage of about 4 times the threshold voltage, if the refractive index ellipsoid of the polymer film is tilted according to the liquid crystal in this way, a more complete viewing angle can be obtained. You can compensate.

The film of FIG. 3 may be tilted with respect to the liquid crystal cell substrate instead of the method of tilting the index ellipsoid 31 with respect to the film surface 32 as shown in FIG. This arrangement is difficult for a direct-view display due to space limitations, but it is an effective means for a projection display.

Example 5 As shown in FIG. 7, the liquid crystal display element in Example 5 of the present invention has an upper polarizing plate 1, a polymer film 2, a liquid crystal cell 3, a polymer film 4 and a lower polarizing plate. 5, upper substrate 6 of liquid crystal cell, lower substrate 7, transparent electrode 8,
It is composed of the nematic liquid crystal 9. Also, the relationship of each axis,
The conditions of the liquid crystal cell are the same as in the case of Example 1 shown in FIG. In Example 5, the upper and lower two polymer films were used, but both are negative optical anisotropic bodies made of polycarbonate, n _x = 1.588, n _y = 1.588, n
_z = 1.585, film thickness d = 50 μm, (n _x −n
The sum of _z ) × d is 0.3 μm.

The voltage transmittance characteristics of this liquid crystal display element are similar to those of the first embodiment shown in FIG. FIG. 8 shows the viewing angle characteristics when the liquid crystal cell is driven with the state of applying 7 V applied to the on state and the state of applying 1 V applied to the off state.
Shown in. By using the upper and lower two polymer films, the viewing angle characteristics are obtained in a wider and left-right symmetry than in Example 1 in which only one film is used.

(Example 6) The cell structure and axial relationship of Example 6 are the same as those of Example 1 shown in FIGS. 1 and 2, except that polyvinyl alcohol is used for the polymer film 2. .. Polyvinyl alcohol has a smaller wavelength dispersion of birefringence Δn than the polycarbonate used in Example 1. Here, the wavelength dispersion value ν of Δn is defined as ν≡Δn (460 nm) / Δn (590 nm) by using Δn for light having a wavelength of 460 nm and Δn for light having a wavelength of 590 nm. The ν value of polyvinyl alcohol is 1.005, and the ν value of polycarbonate is 1.095. Viewing angle characteristics when using polyvinyl alcohol
Although it is almost the same as the case of Example 1 shown in FIG. 5, it is more excellent in that the yellow coloring due to the viewing angle is reduced. The ν value of the liquid crystal ZLI-4393 is 1.085, but if a polymer having a wavelength dispersion value smaller than that of the liquid crystal is used, it is effective in reducing the coloring due to the viewing angle.

(Embodiment 7) The cell structure of Embodiment 7 is shown in FIG.
The first embodiment is similar to the first embodiment, except for the axial relationship. As shown in FIG. 9, the relationship between the axes of Example 7 is as follows: the polarization axis (absorption axis) direction of the upper polarizing plate 1 is 11, the liquid crystal alignment direction of the upper substrate 6 of the liquid crystal cell is 12, and the lower substrate 7 of the liquid crystal cell. The liquid crystal alignment direction is 13, and the polarization axis direction of the lower polarizing plate 5 is 14, 1.
When the angle formed by 1 is 12, the twist angle of the nematic liquid crystal 9 is 22, and the angle formed by 14 is 13, the angles 21 and 23 are 0 degrees, and the angle 22 is 90 degrees.
Set in degrees.

The voltage transmittance characteristic of this liquid crystal display element is similar to that of the first embodiment shown in FIG. FIG. 1 shows the viewing angle characteristics when the liquid crystal cell is driven with an applied state of 7V applied to the liquid crystal cell and an applied state of 1V applied to the liquid crystal cell.
It shows in 0. By making the axial direction of the polarizing plate parallel to the alignment treatment direction of the adjacent liquid crystal cell substrate, the viewing angle characteristics were slightly narrower than the viewing angle characteristics of Example 1 set vertically. However, a viewing angle characteristic wider than the conventional viewing angle characteristic of FIG. 15 is still obtained.

(Embodiment 8) The cell structure of Embodiment 8 is shown in FIG.
The same as Example 1 described above, except that the upper and lower polarizing plates are arranged in parallel. With such an arrangement, a so-called normally black display is displayed in which black is displayed when no voltage is applied and white when a voltage is applied. Although such an arrangement has the effect of enlarging the viewing angle, it is not as great as in the case of normally white display. This is because the viewing angle compensator used in the present invention compensates for the state where the liquid crystal has risen due to the application of a high voltage. Therefore, when a voltage is applied, black is more likely to obtain high contrast in a wider viewing angle range. ..

(Embodiment 9) The liquid crystal cell of Embodiment 9 has the same cell structure, axial relationship, etc. as that of Embodiment 1 shown in FIGS. 1 and 2 and the same voltage transmittance characteristic as that of FIG. The difference is that the state in which 5 V is applied is turned on. The viewing angle characteristics at this time are shown in FIG. 7 V was applied in the on-state of Example 1, but by lowering this voltage, the viewing angle characteristics of Example 1 were slightly narrower than the viewing angle characteristics of FIG. However, the viewing angle characteristics wider than the conventional viewing angle characteristics shown in FIG. 15 are obtained, and the viewing angle can be enlarged without applying a high voltage. Incidentally, it is set to a small value of (n _x -n _z) × d of the polymer film when the high voltage is not applied is desired.

(Embodiment 10) The cell structure and axial relationship of Embodiment 10 are the same as those of Embodiment 1 shown in FIGS. 1 and 2, but
The value of (n _x −n _z ) × d of the polymer film is 0.5 μm
Is different from that of Δn × d of the liquid crystal.
Even if this is done, the viewing angle characteristics are improved, but the effect is small. The (n _x −n _z ) × d value of the polymer film is most preferably set to be equal to or slightly smaller than the Δn × d value of the liquid crystal, and is set to be twice or more the Δn × d value of the liquid crystal. That doesn't make sense.

(Embodiment 11) In the above embodiment,
Although the TN type liquid crystal display device has been described as an example, the present invention is not limited to the TN type liquid crystal display device and can be applied to many other liquid crystal display devices using a nematic liquid crystal having a positive dielectric anisotropy. And well-known EC
B-type liquid crystal and STN-type liquid crystal also have the same effect. In Example 11, an example of ECB type liquid crystal will be given.

The cell structure of the eleventh embodiment is the same as that of the fifth embodiment shown in FIG. As shown in FIG. 12, the relationship between the axes is such that the polarization axis (absorption axis) direction of the upper polarizing plate 1 is 11, the liquid crystal alignment direction of the upper substrate 6 of the liquid crystal cell is 12, and the liquid crystal alignment direction of the lower substrate 7 of the liquid crystal cell. 13, the polarization axis direction of the lower polarizing plate 5 is 14 and the angle formed by 11 is 12, and the twist angle of the nematic liquid crystal 9 determined from 12 and 13 is 22 and 14 is 1.
If the angle formed by 3 is 23, the angles 21 and 23 are set to 45 degrees to the right and the angle 22 is set to 0 degrees.

As the nematic liquid crystal 9, a liquid crystal ZLI-4393 manufactured by Merck Co. was used without adding a chiral dopant, and was injected into a cell having a cell gap d of 3.2 μm. △
n × d becomes 0.27 μm. The two polymer films were the same as in Example 5, n _x = 1.588, n _y = 1.58.
8, n _z = 1.585 using polycarbonate film, but any film thickness d = 45μm, (n _x -
_nz ) × d = 0.24 μm.

FIG. 13 shows the viewing angle characteristics when the liquid crystal cell is driven with 15 V applied to the ON state and 1 V applied to the OFF state. EC like this
Even if the B type liquid crystal is used, a wide viewing angle characteristic equal to or higher than that of the TN type liquid crystal can be obtained. In the case of ECB-type liquid crystal, since in order to obtain a high contrast is required higher voltage than TN liquid crystal, in order to compensate for residual retardation, without equal n _x and n _y of the polymer film _{(n x -n y) × d} = small retardation or leave about 0.01 [mu] m, or when the film as little mentioned in embodiment 4 arranged inclined with respect to the cell substrate, a relatively low voltage But you can get the contrast.

[0039]

As described above, according to the present invention, a liquid crystal display device having excellent viewing angle characteristics can be provided by using a polymer film as a viewing angle compensating plate.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a liquid crystal display element in Examples 1 to 4 and 6 to 10 of the present invention.

FIG. 2 is a relationship diagram of each axis of the liquid crystal display element in Examples 1 to 6, 9 and 10 of the present invention.

FIG. 3 is a schematic view of a refractive index ellipsoid of a polymer film for performing viewing angle compensation used in Examples 1 to 3 and 5 to 11 of the present invention.

FIG. 4 is a diagram showing voltage transmittance characteristics of Examples 1, 5 to 7, 9, 10 and conventional liquid crystal display elements of the present invention.

FIG. 5 is a diagram showing viewing angle characteristics of the liquid crystal display element according to Example 1 of the present invention.

FIG. 6 is a schematic diagram of a refractive index ellipsoid of a polymer film for performing viewing angle compensation used in Example 4 of the present invention.

FIG. 7 is a cross-sectional view of a liquid crystal display element in Examples 5 and 11 of the present invention.

FIG. 8 is a diagram showing viewing angle characteristics of a liquid crystal display element according to Example 5 of the present invention.

FIG. 9 is a relationship diagram of each axis of the liquid crystal display element according to the seventh embodiment of the present invention.

FIG. 10 shows a liquid crystal display element according to Example 7 of the present invention,
It is a figure which shows a viewing angle characteristic.

FIG. 11 shows a liquid crystal display element in Example 9 of the present invention,
It is a figure which shows a viewing angle characteristic.

FIG. 12 is a relationship diagram of each axis of the liquid crystal display element in Example 11 of the present invention.

FIG. 13 is a diagram showing viewing angle characteristics of a liquid crystal display element according to Example 11 of the present invention.

FIG. 14 is a cross-sectional view of a conventional TN type liquid crystal display element.

FIG. 15 is a diagram showing viewing angle characteristics of a conventional TN type liquid crystal display element.

[Explanation of symbols]

 1 Upper Polarizing Plate 2 Polymer Film 3 Liquid Crystal Cell 4 Polymer Film 5 Lower Polarizing Plate 6 Upper Substrate of Liquid Crystal Cell 7 Lower Substrate of Liquid Crystal Cell 8 Transparent Electrode 9 Nematic Liquid Crystal with Positive Dielectric Anisotropy 11 Upper Side Polarization axis direction of the polarizing plate 1 12 Liquid crystal alignment direction of the upper substrate 6 of the liquid crystal cell 13 Liquid crystal alignment direction of the lower substrate 7 of the liquid crystal cell 14 Polarization axis direction of the lower polarizing plate 5 Angle between 11 and 12 22 Nematic liquid crystal 9 Angle of twist 23 14 angle formed with 13 31 refractive index ellipsoid of polymer film 32 film surface of polymer film 41 isocontrast curve with contrast ratio 1: 1 42 isocontrast curve with contrast ratio 1: 3 43 contrast ratio 1 : 10 equal contrast curve 44 equal contrast curve 1:30 contrast ratio 45 equal contrast curve 1: 100 contrast ratio Trust curve 46 contrast ratio of 1: 300 iso-contrast curve of

Claims (12)

[Claims] 1. A liquid crystal cell in which a nematic liquid crystal having a positive dielectric anisotropy is sandwiched between a pair of substrates, at least one polymer film, and a pair of polarized lights arranged on both sides sandwiching them. A liquid crystal display device comprising a plate, wherein the polymer film is a negative optical anisotropic body having an optical axis in a direction normal to the liquid crystal cell substrate. 2. A liquid crystal cell in which a nematic liquid crystal having a positive dielectric anisotropy is sandwiched between a pair of substrates, at least one polymer film, and a pair of polarized lights arranged on both sides sandwiching them. In a liquid crystal display device including a plate, the polymer film is a negative optical anisotropic body having an optical axis in a direction substantially parallel to the average direction of the liquid crystal director when an on-voltage is applied. Liquid crystal display device. 3. The twist angle of the liquid crystal of the liquid crystal cell is about 90.
The liquid crystal display element according to claim 1 or 2, wherein the liquid crystal display element is in degrees. 4. The polarizing plate is arranged so that the transmission axis of the polarizing plate is perpendicular to the alignment treatment direction of the liquid crystal cell substrates adjacent to each other or sandwiching the polymer film therebetween. Liquid crystal display device. 5. The liquid crystal display element according to claim 1, wherein the twist angle of the liquid crystal of the liquid crystal cell is about 0 degree. 6. The liquid crystal display element according to claim 1, wherein the liquid crystal display element performs bright display when no voltage is applied and dark display when voltage is applied. 7. The liquid crystal display device according to claim 1, wherein the pretilt angle of the liquid crystal is 5 degrees or more. 8. The anchoring energy between the liquid crystal and at least one substrate of the liquid crystal cell is 1 × 10 ⁻⁴ J /
The liquid crystal display device according to claim 1 or 2, wherein the liquid crystal display device has a size of m ² or less. 9. The liquid crystal display according to claim 1, wherein when driving the liquid crystal cell, an effective voltage when turned on is set to be four times or more a threshold voltage of the liquid crystal cell. element. 10. The polymer film is arranged above and below a liquid crystal cell, and the polymer film is arranged above and below the liquid crystal cell.
The liquid crystal display element described. 11. The polymer film of (n _x −n _z ) ×
3. The liquid crystal display device according to claim 1, wherein the sum of the values of d is equal to or smaller than the value of Δn × d of the liquid crystal cell. 12. The liquid crystal display device according to claim 1, wherein the Δn wavelength dispersion value ν of the polymer film is smaller than that of the liquid crystal.