JPH10170906A - Reflection-type liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to execute a good black display, which is low in reflectivity and is colorless, by using two sheets of phase plates and specifying the relation between each of the optical axes of these phase plates, the product of refractive index anisotropy and thickness, and the absorption axis of a polarizing plate. SOLUTION: This liquid crystal display device is constituted by successively laminating the polarizing plate 4, the phase plate 2, the phase plate 1, STN liquid crystals 3 and a reflection plate 5 from an external light incident side. The liquid crystal molecules in an liquid crystal layer has a twisted structure of 220 to 260 deg. in twist angle θ. The product Δnd of the refractive index anisotropy of Δn of the liquid crystals and the thickness d of the liquid crystal layer 3 is 0.5 to 0.8μm. The conditions, such as -105 deg.<ϕ1 -ϕ0 <-10 deg., -85 deg.<ϕ2 -ϕ1 <-20 deg., -50 deg.<γ-ϕ2 <-80 deg., 0.02μm<Δnd1 <0.18μm, 0.32μm<Δnd2 <0.42μm are satisfied when the orientation direction of the liquid crystal molecules on the substrate surface on a first refractive film side is defined as ϕ0 , the direction of the absorption axis of the polarizing plate 4 as γ, the directions of the optical axes of the two double refractive films as ϕ1 , ϕ2 , and the Δnd of the two double refractive films as Δnd1 and Δnd2 .

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, and more particularly to a reflection type liquid crystal display device which can be driven in a time-division manner and realizes a bright display without using a backlight.

[0002]

2. Description of the Related Art At present, STN (Super Twisted Nemti) is used.
c) A reflective liquid crystal display device using -LCD is commercially available. However, this method has a problem that the reflectance is low and a shadow appears on the display.

In the STN-LCD, a glass substrate having a thickness of about 1 mm is interposed between the reflection plate and the liquid crystal. On the other hand, since the size of the pixel is about 300 × 100 μm, light that is obliquely incident on the liquid crystal panel passes through different pixels when it is incident and after it is reflected. Therefore, when the liquid crystal display device is viewed obliquely, it looks as if the shadow of the display object is reflected on the reflector.

As a countermeasure, a reflective STN-LCD (single polarizing plate type STN-LC) capable of displaying with a single polarizing plate is used.
D) The method using (Proposal for Liquid Crystal Symposium in 1994, p.
pp. 206-207).

A conventional STN-LCD requires two polarizing plates for absorbing light other than a predetermined linearly polarized light, whereas a single polarizing plate type STN-LCD can display a single sheet. Can be improved.

Further, in the conventional STN-LCD, it was necessary to provide a reflection plate outside the polarizing plate attached to the liquid crystal panel. However, in the single polarizing plate type STN-LCD, the polarizing plate on the reflection plate side was omitted. Therefore, it is possible to solve the above-mentioned shadow problem by providing a reflection plate in the liquid crystal panel.

This method comprises a single polarizing plate, an STN liquid crystal cell incorporating a reflecting plate, and a birefringent film (phase plate) provided between the polarizing plate and the liquid crystal cell. The phase plate is optimized to realize a monochrome display.

[0008]

The above prior art has a problem that good black display cannot be realized. In order to realize good black display, it is necessary to realize a sufficiently low reflectance in the visible wavelength range of 400 to 700 nm.

However, in the single-polarizer type STN-LCD using one phase plate as in the prior art, a low reflectance is realized only for a specific wavelength, and a low reflectance is realized over all wavelength ranges. I can't. Usually, the phase plate is optimized so that a low reflectance can be realized for a green wavelength having high visibility, but a low reflectance is not necessarily realized for other wavelengths. As a result, the color became bluish black or brown, and good black display could not be realized.

An object of the present invention is to solve the above-mentioned problems of the prior art and to provide a reflection type liquid crystal display device which realizes a good black display which is low in reflectance and achromatic.

[0011]

In order to solve the above-mentioned problems, two phase plates are used, the optical axis of the phase plate, the product of the refractive index anisotropy Δn and the thickness d (Δnd), and the polarizing plate are used. The relationship with the absorption axis was determined.

That is, a liquid crystal cell in which a liquid crystal layer is inserted between a pair of substrates having a reflector and an electrode, a first birefringent film, a second birefringent film, and a polarizing plate are arranged in this order. The liquid crystal molecules in the liquid crystal layer have a twist structure in which the twist angle θ is from 220 ° to 260 ° from the substrate on the reflection plate side to the opposite substrate, and the refractive index anisotropy Δn of the liquid crystal and the thickness d of the liquid crystal layer Is 0.5 to 0.8 μm, the orientation direction of liquid crystal molecules on the substrate surface on the first birefringent film side is φ ₀ , the direction of the absorption axis of the polarizing plate is γ, , The direction of the optical axis of the second birefringent film is φ ₁ ,
φ ₂ and Δnd of the _first and _second birefringent films are Δnd ₁ and Δnd ₂ , respectively, and (I) −105 °
<Φ ₁ −φ ₀ <−10 °, −85 ° <φ ₂ −φ ₁ <−20
°, 50 ° <γ-φ ₂ <80 °, 0.02 μm <Δnd ₁
<0.18 μm, 0.32 μm <Δnd ₂ <0.42 μm,
Or (II) −10 ° <φ ₁ −φ ₀ <40 °, −75 °
<Φ ₂ −φ ₁ <−55 °, 10 ° <γ−φ ₂ <30 °, 0.1 °
12 μm <Δnd ₁ <0.24 μm, 0.32 μm <Δn
d ₂ <0.42 μm or (III) −105 ° <φ ₁ −
φ ₀ <−50 °, 55 ° <φ ₂ −φ ₁ <80 °, −60 °
<Γ-φ ₂ <-20 °, 0.32 μm <Δnd ₁ <0.46
μm, 0.32 μm <Δnd ₂ <0.42 μm, or
(IV) 25 ° <φ ₁ −φ ₀ <75 °, 60 ° <φ ₂ −φ ₁ <
80 °, 5 ° <γ−φ ₂ <55 °, 0.32 μm <Δnd
₁ <0.42 μm, 0.32 μm <Δnd ₂ <0.42 μ
m or (V) 5 ° <φ ₁ −φ ₀ <90 °, -75 °
<Φ ₂ −φ ₁ <−10 °, −75 ° <γ−φ ₂ <−10
°, 0.04 μm <Δnd ₁ <0.22 μm, 0.04 μm
<Δnd ₂ <0.22 μm or (VI) 60 ° <φ ₁
−φ ₀ <90 °, 55 ° <φ ₂ −φ ₁ <80 °, −35 °
<Γ−φ ₂ <−10 °, 0.32 μm <Δnd ₁ <0.42
μm, and 0.12 μm <Δnd ₂ <0.22 μm.

[0013] Further, there is provided a reflection type liquid crystal display device in which the liquid crystal cell has a color filter and the reflection plate is provided inside the liquid crystal cell.

In the above, when circularly polarized light is incident on the liquid crystal cell from the reflector in a state where a voltage for dark display is applied between the electrodes, when the light is incident on the polarizer, at least red, The optical axis, Δnd, of the phase plate is specified so that the light becomes substantially linearly polarized light with respect to the wavelengths of green and blue, and its polarization direction substantially matches the absorption axis of the polarizing plate.

[0015] This makes it possible to realize an achromatic black display with a low reflectance at the time of dark display and a reflective liquid crystal display device having a high reflectance and producing no shadow. The details of the operation and effect will be described later.

[0016]

Embodiments of the present invention will be described below with reference to the drawings.

Embodiment 1 FIG. 1 shows the structure of an embodiment of the reflection type liquid crystal display device of the present invention. The polarizing plate 4, the phase plate 2, the phase plate 1, the STN liquid crystal 3, and the reflection plate 5 are sequentially laminated from the side where external light is incident. Although illustration is omitted in FIG. 1, a voltage application unit for driving and displaying the STN liquid crystal 3 is provided.

FIG. 2 shows an optical angle of each optical member of the liquid crystal display device of FIG. The absorption axis 14 of the polarizing plate 4, the optical axis 11 of the phase plate 1, the optical axis 12 of the phase plate 2, and the orientation direction 10 of the liquid crystal molecules on the phase plate side of the STN liquid crystal 3 are denoted by γ,
Defined by φ ₁ , φ ₂ , φ ₀ .

The liquid crystal molecules of the STN liquid crystal 3 have a twisted structure from the reflection plate 5 side to the phase plate 1 side, and the alignment direction 10 of the liquid crystal molecules on the phase plate 1 side and the liquid crystal molecules on the reflection plate 5 side. The angle formed with the orientation direction 13 is defined by the twist angle θ.

In the present embodiment, the phase plate 1 is
The case where liquid crystal molecules are twisted and aligned counterclockwise toward the side will be described as an example.

The angle of each element is defined counterclockwise with respect to the x direction. Further, φ ₀ = (θ / 2) + 90 °.

Next, conditions for the liquid crystal display device of the present embodiment to realize a sufficiently low reflectance for red, green, and blue wavelengths at the time of dark display and the operation at that time will be described.

After external light incident from the polarizing plate 4 side passes through the polarizing plate 4, the phase plate 2, the phase plate 1, and the STN liquid crystal 3,
It is known that the reflectance of this element becomes 0 if the light is circularly polarized on the reflection plate 5, that is, at the point A in FIG. In this case, conversely, when circularly polarized light is incident from the point A toward the STN liquid crystal 3, the polarization direction at the point D is changed to the polarization plate 4.
Becomes linearly polarized light parallel to the absorption axis.

Therefore, when circularly polarized light is incident from the point A in a state where a voltage for dark display is applied to the STN liquid crystal 3, the polarization state at the point D changes with respect to the red, green, and blue wavelengths. If the phase plates 1 and 2 and the polarizing plate 4 are selected so that they become substantially the same linearly polarized light and the direction of polarization becomes substantially parallel to the absorption axis of the polarizing plate 4, the wavelengths of red, green and blue can be obtained. A sufficiently low reflectance can be realized.

When the elliptically polarized light passes through the phase plates 1 and 2, a phase difference occurs between a component parallel to the optical axis of the phase plate and a component perpendicular thereto, but the absolute values of both components do not change. Therefore, assuming a rectangle whose long side or short side is parallel to the optical axis of the phase plate, and inscribes an ellipse representing elliptically polarized light before passing through the phase plate, elliptically polarized light after passing through the phase plate is also You will be inscribed in the rectangle. At this time, if the phase difference generated by the phase plate is selected, linearly polarized light can be obtained. However, since this linearly polarized light is also inscribed in the rectangle, the polarization direction is the diagonal direction of the rectangle.

FIG. 3 is a diagram showing elliptically polarized light having red, green, and blue wavelengths at point C in FIG. In the above description, to obtain the same linearly polarized light, red, green, and blue elliptically polarized light are obtained at the point C, and the same linearly polarized light is obtained at the point D regardless of the red, green, and blue wavelengths. As shown in FIG. 3, the red, green, and blue elliptically polarized lights at point C need to be inscribed in the same rectangle.

The polarization state immediately after transmission of the STN liquid crystal, that is,
At point B, this condition is generally not satisfied. Therefore,
With a single phase plate, the same linearly polarized light cannot be obtained regardless of the difference in wavelength.

Therefore, in the present embodiment, the phase plate 1 is selected so as to satisfy the above condition at the point C. Δ of phase plate 1
nd is the absolute value Ex of the component parallel to the optical axis of the phase plate 1 of the complex electric field vector representing the elliptically polarized light at the point B, the absolute value Ey of the vertical component, the phase difference δ ₀ between the parallel component and the vertical component, optical axes phi ₁ of the phase plate 1, the optical axis phi ₂ of the phase plate 2 and the absorption axis of the polarizing plate gamma, using a wavelength of light lambda, it is determined by the following formula (1).

[0029]

(Equation 1)

Next, the polarized light at point C after passing through the phase plate 1 passes through the phase plate 2 and at point D at least with respect to the wavelengths of red, green, and blue, the polarization direction of the polarizing plate 4. The phase plate 2 is selected so as to have the same linearly polarized light parallel to the absorption axis.

The Δnd of the phase plate 2 is expressed by the following equation using the phase difference δ ₁ between the component parallel to and perpendicular to the optical axis of the phase plate 2 of the complex electric field vector representing the polarization state at the point C, and the wavelength λ of light. Determined in [2].

[0032]

(Equation 2)

For each of the red, green, and blue wavelengths, Δnd of the phase plate 1 is calculated by the above equation [1], and Δnd of the phase plate 2 is calculated by the equation [2].
If nd are determined independently, any γ, φ ₁ , φ ₂
Of the red, green, and blue wavelengths for the combination of
It is possible.

However, Δnd of red, green and blue wavelengths
There is a certain relationship between them that depends on the material. For example, in the case of a polycarbonate film, the red wavelength Δn
d is about 0.97 times the green wavelength Δnd and the blue wavelength Δn
d is about 1.07 times Δnd of the green wavelength. Therefore,
Generally, the reflectance cannot be set to 0 for all the red, green, and blue wavelengths.

Therefore, in the present embodiment, the value of Δnd of the phase plate is determined from the equations [1] and [2] for the green wavelength having high visibility, and the optical member (material) satisfying this is determined. Are used, the conditions of γ, φ ₁ , φ ₂ , Δnd ₁ , and Δnd ₂ at which the red and blue reflectances can be sufficiently reduced are determined.

Since the object of the present invention is to achieve a good black display at the time of dark display which cannot be realized by a single phase plate, a sufficiently low reflectivity can be obtained by a single phase plate. It was defined as a reflectance lower than the reflectance.

[0037] Figure 4, the reflectance of the reflectance R _R and blue dark display red can be realized by a single phase plate average value of _{R B} (R R + R
_B ) / 2 (%) and Δnd of the STN liquid crystal.

The twist angle of the STN liquid crystal 3 is 220 °, 2
40 ° and 260 ° are shown. The value of Δnd of the phase plate is selected so that the polarization after transmission through the STN liquid crystal becomes linear polarization after transmission through the phase plate with respect to the green wavelength, and the direction of the absorption axis of the polarization plate is changed to the polarization direction of the linear polarization. Matched.

In this case, the value of (R _R + R _B ) / 2 depends on the optical axis of the phase plate, and is obtained when the optical axis is changed.
The minimum value of (R _R + R _B ) / 2 was plotted.

Here, the reflectivity was defined as the reflected light in the vertical direction when the light was vertically incident on the element. In this condition,
Δnd = 0.58 in a 240 ° twisted STN liquid crystal cell
In the case of μm, the reflectance of dark display becomes minimum. Therefore, this reflectance was defined as a reference reflectance, and a condition that the red and blue reflectances were lower than the reference reflectance was determined.

In this embodiment, when the reflectance of red and blue becomes lower than the reference reflectance, φ ₁ , φ ₂ , γ, Δnd ₁ ,
The combinations of Δnd ₂ can be classified into the following six cases I to VI. The STN liquid crystal cell was studied by changing the twist angle from 220 ° to 260 ° and Δnd from 0.5 to 0.8 μm.

FIG. 5 is a diagram showing the relationship among φ ₁ , φ ₂ , and γ of case I. FIG. 6 is a diagram showing the relationship between Δnd ₁ and Δnd ₂ .

As parameters, the optical axis 11 of the phase plate 1
Makes an angle φ with the orientation direction 10 of the liquid crystal molecules on the phase plate side.
₁₋ φ ₀ , the optical axis 12 of the phase plate 2 is
Reference reflection angle phi ₂ -.phi _1, the absorption axis 14 of the polarizing plate 4 is plotted by taking the angle gamma-phi ₂ to the optical axis 12 of the phase plate 2, red, blue reflectance of relative The conditions for lowering the rate are as follows, as shown in FIGS.

[0044]

(I) −105 ° <φ ₁ −φ ₀ <−10 ° −85 ° <φ ₂ −φ ₁ <−20 ° 50 ° <γ−φ ₂ <80 ° 0.02 μm <Δnd ₁ < 0.18 μm 0.32 μm <Δnd ₂ <0.42 μm Similarly, φ ₁ , φ ₂ , γ, Δnd ₁ , Δnd of cases II to VI
The relationship of ₂ is shown in FIGS.

[0045]

(II) −10 ° <φ ₁ −φ ₀ <40 ° −75 ° <φ ₂ −φ ₁ <−55 ° 10 ° <γ−φ ₂ <30 ° 0.12 μm <Δnd ₁ <0 .24 μm 0.32 μm <Δnd ₂ <0.42 μm (III) −105 ° <φ ₁ −φ ₀ <−50 ° 55 ° <φ ₂ −φ ₁ <80 ° −60 ° <γ−φ ₂ <−20 ° 0.32 μm <Δnd ₁ <0.46 μm 0.32 μm <Δnd ₂ <0.42 μm (IV) 25 ° <φ ₁ −φ ₀ <75 ° 60 ° <φ ₂ −φ ₁ <80 ° 5 ° <γ −φ ₂ <55 ° 0.32 μm <Δnd ₁ <0.42 μm 0.32 μm <Δnd ₂ <0.42 μm (V) 5 ° <φ ₁ −φ ₀ <90 ° −75 ° <φ ₂ −φ ₁ < −10 ° −75 ° <γ−φ ₂ <−10 ° 0.04 μm <Δnd ₁ <0.22 μm 0.04 μm <Δnd ₂ <0.22 μm (VI) 60 ° <φ ₁ −φ ₀ <90 ° 55 _{° <φ 2 -φ 1 <80} ° -35 ° <γ-φ 2 <-1 _{° 0.32μm <Δnd 1 <0.42μm 0.12μm} <Δnd 2 < As described above _{0.22μm, φ 1, φ 2,} γ, Δnd 1, the [Delta] nd _2, any of the above Case I through Vl By setting these conditions, it is possible to realize a reflective liquid crystal display device having sufficiently low red, green, and blue reflectances in dark display.

Hereinafter, the reflectance-applied voltage characteristics and the reflectance-wavelength characteristics will be described with reference to typical examples of cases I to VI.

Reflectivity of case I, II, III, IV, V, VI
Applied voltage characteristics are shown in FIGS.
FIG. 18, FIG. 20, and FIG.
2, 24, 26 and 28.

In the reflectance-wavelength characteristics, the characteristics at the time of bright display and dark display when the liquid crystal display device is driven at 1/240 duty are shown. In each case, the twist angles θ and Δnd of the STN liquid crystal 3, the optical axes φ ₁ and Δnd _{1 of} the phase plate ₁ ,
Table 1 shows the optical axes φ ₂ and Δnd _{2 of the} phase plate 2 and the absorption axis γ of the polarizing plate 4.

[0049]

[Table 1]

17 to 28, the broken lines show the characteristics when (R _R + R _B ) / 2 becomes the lowest when one phase plate is used, and are shown for comparison with the present embodiment.

When one or two phase plates are used, Δnd of the phase plate is selected so that the reflectivity becomes 0 with respect to the green wavelength. Therefore, in the vicinity of the green wavelength of 0.55 μm, In both cases, the dark display has a sufficiently low reflectance. However, the red and blue wavelengths around 0.62 μm and 0.45 μm
It can be seen that in the vicinity of μm, the reflectivity is suppressed to a lower value than in the case where only one phase plate is used.

As described above, the twist angle θ is 220 ° or more.
In the reflection type liquid crystal display device having the configuration shown in FIG. 1 using an STN liquid crystal having 260 ° and Δnd of 0.5 to 0.8 μm,
The optical axes φ ₁ , Δnd _{1 of} the phase plate ₁ , the optical axes φ ₂ , Δnd _{2 of the} phase plate 2, and the absorption axis γ of the polarizing plate 4 are set in any range of cases I to VI shown in FIGS. By setting, it is possible to realize a favorable dark display with a lower reflectance and achromatic color than when only one phase plate is used.

In the present embodiment, γ is set to
Although the description is made with the absorption axis defined as, the same effect can be obtained as the transmission axis.

Embodiment 2 Next, an example in which color filters are combined will be described with reference to FIG.

The liquid crystal display device shown in FIG.
2, reflector 5, transparent insulator 82, transparent electrode 62, STN
Liquid crystal 3, transparent electrode 61, flattening layer 81, color filter 90, glass substrate 71, phase plate 1, phase plate 2, polarizing plate 4
Are sequentially laminated.

The color filter 90 and the reflecting plate 5 are provided on the STN liquid crystal 3 side (inside) on the glass substrates 71 and 72 facing each other, but the color filter 90 is provided on the reflecting plate 5 on the substrate 72. The same effect can be obtained.

Further, the same effect can be obtained by using the transparent electrode 62 instead of the reflector 5 as a member reflecting light such as aluminum.

The twist angle θ of the STN liquid crystal 3 of this embodiment is in the range of 220 ° to 260 °, and Δnd is in the range of 0.5 to 0.8 μm. The optical axes φ ₁ and Δnd _{1 of} the phase plate ₁ , the optical axes φ ₂ and Δnd _{2 of the} phase plate 2, and the absorption axis γ of the polarizing plate 4 are shown in FIGS.
It is set in any of the ranges of case I to VI shown in FIG.

The reflection plate 5 is formed by depositing aluminum or the like on a glass substrate 72 by vapor deposition or the like. Further, the surface is provided with a diffusivity so as not to be a mirror surface. This diffusibility imparting means can be achieved by, for example, roughening the surface of the glass substrate 72 before vapor deposition.

Between the color filter 90 and the reflection plate 5,
The transparent insulator 82, the transparent electrode 62, the STN liquid crystal 3, the transparent electrode 61, and the flattening layer 81 are interposed, all of which are several μm larger than a normal pixel size (about 300 × 100 μm).
Therefore, the problem of shadow as described in the related art does not occur.

Further, the optical axes φ ₁ , Δnd ₁ ,
The optical axes φ ₂ and Δnd _{2 of the} phase plate 2 and the absorption axis γ of the polarizing plate 4
Is set to one of the ranges of cases I to VI shown in FIGS. 5 to 16, so that the reflectance in dark display is reduced not only for the green wavelength but also for the red and blue wavelengths. be able to.

In the present embodiment, for example, when displaying green, the leakage light from the red and blue pixels can be suppressed sufficiently low, so that color display with high color purity is possible. On the other hand, in the related art, since the reflectance cannot be sufficiently low at the time of dark display with respect to the wavelengths of red and blue, the leakage light from the red and blue pixels is mixed with the green light, resulting in poor color purity. turn into.

As described above, the present invention is very effective in a color display having a high color purity, particularly in a reflection type color liquid crystal display device in which color filters are combined.

[0064]

According to the present invention, in a reflection type liquid crystal display device having a high reflectance and no shadow, a good black display with low reflectance at the time of dark display and achromatic color is realized. be able to.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view illustrating a configuration of a liquid crystal display device according to an example of the present invention.

FIG. 2 is a view showing optical angles of respective optical members of the liquid crystal display device of FIG.

FIG. 3 is a diagram showing elliptically polarized light having red, green, and blue wavelengths at point C in FIG. 1;

FIG. 4 is a diagram showing the relationship between the reflectance of red and blue for dark display and the Δnd of the phase plate, which can be realized by a single phase plate.

FIG. 5 is a diagram showing a relationship among φ ₁ , φ ₂ , and γ of case I according to the embodiment of the present invention.

FIG. 6 shows φ ₁ , φ ₂ , and Δn of case I according to the embodiment of the present invention.
d _1, is a diagram showing the relationship between [Delta] nd _2.

FIG. 7 is a diagram showing the relationship among φ ₁ , φ ₂ , and γ in case II of the example of the present invention.

FIG. 8 shows φ ₁ , φ ₂ , Δn of case II according to the embodiment of the present invention.
d _1, is a diagram showing the relationship between [Delta] nd _2.

FIG. 9 is a diagram showing the relationship among φ ₁ , φ ₂ , and γ in case III of the example of the present invention.

FIG. 10 shows φ ₁ , φ ₂ , and Δn of case III of the embodiment of the present invention.
d _1, is a diagram showing the relationship between [Delta] nd _2.

FIG. 11 is a diagram showing the relationship among φ ₁ , φ ₂ , and γ in case IV of the example of the present invention.

FIG. 12 shows φ ₁ , φ ₂ , and Δn of case IV of the embodiment of the present invention.
d _1, is a diagram showing the relationship between [Delta] nd _2.

FIG. 13 is a diagram showing a relationship among φ ₁ , φ ₂ , and γ of case V according to the embodiment of the present invention.

FIG. 14 shows φ ₁ , φ ₂ , and Δn of case V according to the embodiment of the present invention.
d _1, is a diagram showing the relationship between [Delta] nd _2.

FIG. 15 is a diagram showing the relationship among φ ₁ , φ ₂ , and γ in case VI of the example of the present invention.

FIG. 16 shows φ ₁ , φ ₂ , and Δn of case VI of the embodiment of the present invention.
d _1, is a diagram showing the relationship between [Delta] nd _2.

FIG. 17 is a diagram showing a reflectance-applied voltage characteristic of case I of the example of the present invention.

FIG. 18 is a diagram showing a reflectance-wavelength characteristic of case I of the example of the present invention.

FIG. 19 is a diagram showing a reflectance-applied voltage characteristic of case II of the example of the present invention.

FIG. 20 is a diagram showing the reflectance-wavelength characteristics of case II of the example of the present invention.

FIG. 21 is a diagram showing the reflectance-applied voltage characteristic of case III of the example of the present invention.

FIG. 22 is a diagram showing the reflectance-wavelength characteristics of case III of the example of the present invention.

FIG. 23 is a diagram showing the reflectance-applied voltage characteristics of case IV of the example of the present invention.

FIG. 24 is a diagram showing the reflectance-wavelength characteristics of case IV of the example of the present invention.

FIG. 25 is a diagram showing a reflectance-applied voltage characteristic of case V according to the example of the present invention.

FIG. 26 is a diagram showing a reflectance-wavelength characteristic of case V of the example of the present invention.

FIG. 27 is a diagram showing the reflectance-applied voltage characteristics of case VI of the example of the present invention.

FIG. 28 is a diagram showing a reflectance-wavelength characteristic of case VI of the example of the present invention.

FIG. 29 is a schematic cross-sectional view illustrating a configuration of a color liquid crystal display element according to an example of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Phase plate, 2 ... Phase plate, 3 ... STN liquid crystal, 4 ... Polarizing plate, 5 ... Reflection plate, 10 ... Orientation direction of STN liquid crystal molecule on the phase plate side, 11 ... Direction of optical axis of phase plate 1, 12 ... the direction of the optical axis of the phase plate 2, 13 ... the orientation direction of the STN liquid crystal molecules on the polarizing plate side, 14 ... the absorption axis of the polarizing plate, 61, 62 ... transparent electrodes, 71, 72 ... the glass substrate, 81 ... the flattening film , 82 ...
Transparent insulating film, 90 ... color filter.

Claims (3)

[Claims] 1. A liquid crystal cell in which a liquid crystal layer is inserted between a pair of substrates having a reflector and an electrode, a first birefringent film, a second birefringent film, and a polarizing plate are arranged in this order.
The liquid crystal molecules in the liquid crystal layer have a twist structure in which the twist angle θ is from 220 ° to 260 ° from the substrate on the reflection plate side to the opposite substrate, and the refractive index anisotropy Δn of the liquid crystal and the thickness of the liquid crystal layer The product Δnd with d is 0.5 to 0.8 μm, the orientation direction of liquid crystal molecules on the substrate surface on the first birefringent film side is φ ₀ , the direction of the absorption axis of the polarizing plate is γ, The directions of the optical axes of the first and second birefringent films are φ ₁ and φ ₂ , and Δnd of the first and second birefringent films is Δnd.
₁ and Δnd ₂ , (I) −105 ° <φ ₁ −φ ₀ <−
10 °, −85 ° <φ ₂ −φ ₁ <−20 °, 50 ° <γ−
φ ₂ <80 °, 0.02 μm <Δnd ₁ <0.18 μm,
0.32 μm <Δnd ₂ <0.42 μm, or (II)
−10 ° <φ ₁ −φ ₀ <40 °, −75 ° <φ ₂ −φ ₁ <−
55 °, 10 ° <γ−φ ₂ <30 °, 0.12 μm <Δn
d ₁ <0.24 μm, 0.32 μm <Δnd ₂ <0.42 μ
m or (III) −105 ° <φ ₁ −φ ₀ <−50
°, 55 ° <φ ₂ -φ ₁ <80 °, -60 ° <γ-φ ₂ <
−20 °, 0.32 μm <Δnd ₁ <0.46 μm, 0.3
2 μm <Δnd ₂ <0.42 μm or (IV) 25 °
<Φ ₁ −φ ₀ <75 °, 60 ° <φ ₂ −φ ₁ <80 °, 5 °
<Γ-φ ₂ <55 °, 0.32 μm <Δnd ₁ <0.42 μ
m, 0.32 μm <Δnd ₂ <0.42 μm, or
(V) 5 ° <φ ₁ −φ ₀ <90 °, −75 ° <φ ₂ −φ ₁ <
−10 °, −75 ° <γ−φ ₂ <−10 °, 0.04 μm
<Δnd ₁ <0.22 μm, 0.04 μm <Δnd ₂ <0.2
22 μm, or (VI) 60 ° <φ ₁ −φ ₀ <90 °,
55 ° <φ ₂ −φ ₁ <80 °, −35 ° <γ−φ ₂ <−1
0 °, 0.32 μm <Δnd ₁ <0.42 μm, 0.12 μ
A reflection type liquid crystal display device characterized by satisfying one of the following conditions: m <Δnd ₂ <0.22 μm. 2. The liquid crystal cell has a color filter,
2. The reflection type liquid crystal display device according to claim 1, wherein the reflection plate is provided inside a liquid crystal cell. 3. The reflection type liquid crystal display device according to claim 2, wherein a color filter is provided on the reflection plate.