JP2000347155A - Optical display - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide an optical display device which reduces the influence of multiple interference, has little luminance change and glare over a wide range of viewing angles, and is particularly suitable for a stereoscopic display device, a liquid crystal shutter and the like. SOLUTION: In an optical display device including a liquid crystal element including a liquid crystal layer sandwiched between a pair of substrates with transparent electrodes, a polarizing plate provided on the surface of the substrate, and a light source, a normal line of the liquid crystal element is provided. The angle (θ) of the light emitting direction with respect to
In the case of 60 °, when each light transmittance measured at each measurement interval Δθ is T (θ), and the average value is _Tave , the interference degree represented by the following equation (1) I) is 0
It is set to a value within the range of 0.09. (Equation 1)

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an optical display device. More specifically, the present invention relates to an optical display device suitable for a stereoscopic display device, a color liquid crystal shutter, and the like, in which occurrence of multiple interference is reduced.

[0002]

2. Description of the Related Art In recent years, a liquid crystal shutter is installed in front of a cathode ray tube, the liquid crystal shutter is driven at a high speed in accordance with the frame frequency of the cathode ray tube, and the image of the cathode ray tube is switched in a time-division manner so that stereoscopic display is realized. A device has been proposed. Such a stereoscopic display device is disclosed in, for example, Japanese Patent Publication No. 5-78017 and Japanese Patent Application Laid-Open No. 61-22 / 1986.
No. 7498. In addition, for example, Japanese Patent Publication No. 4-49928 discloses a first to third color polarizers having at least two orthogonal color selection polarization axes,
A color filter (color liquid crystal shutter) having first and second variable retardation plates for giving retardation only to a specific color and control means for the variable retardation plate is disclosed.

Further, as a prior art relating to a liquid crystal display element, Japanese Patent Application Laid-Open No. Hei 2-13926 discloses an invention relating to a liquid crystal device using a ferroelectric liquid crystal. The thickness of the electrode is 840 ° or less, 1320 to 1680 °, 1960 to 2470 °, or 3180 to 3850 °, and the thickness of the ferroelectric liquid crystal is 5 μm or less. A phosphor light source equipped with a kind of phosphor is used.

Japanese Patent Application Laid-Open No. 61-174511 discloses an invention relating to a liquid crystal display device having an insulating film. In order to reduce reflected light, the thickness of a transparent electrode is reduced by about 5 mm.
500 / (2 · refractive index of transparent electrode) Å
The thickness of the insulating film is about 5500 / (2 · refractive index of the insulating film) Å
And

Further, Japanese Patent Application Laid-Open No. 59-60469 discloses an invention relating to a liquid crystal display device having a reflectance adjusting layer. The refractive index of the liquid crystal layer and the refractive index of the transparent electrode layer are set to an intermediate value.
Å800 °, and the thickness of the transparent electrode layer is from 1300 to 140
0 °.

[0006] Japanese Patent Application Laid-Open No. 10-123522 discloses an invention relating to a substrate for a liquid crystal display element. In order to provide an alignment film with an antireflection function, the thickness (D) of the alignment film and the reflection factor are determined. The wavelength (λ) intended to be prevented is related to the refractive index (n) of the alignment film, and the thickness (D) of the alignment film is set to a value of 1000 ° or less.

Japanese Patent Application Laid-Open No. 9-015657 discloses an invention relating to a liquid crystal optical shutter. The purpose of the invention is to reduce reflection caused by thin film interference and obtain a liquid crystal shutter having a high transmittance. It has two liquid crystal panels that turn on and off light transmission of a specific wavelength determined by Δnd, and the thickness of the insulating film present on each panel is different so that the reflectance at the specific wavelength is minimized. It is characterized by.

Japanese Patent Application Laid-Open No. HEI 7-168173 discloses an invention relating to a liquid crystal display device. In order to prevent the occurrence of interference fringes due to non-uniform cell thickness, a back light source is disclosed. It is characterized in that the transparent electrode and the insulating film are formed with a film thickness having a low reflectance with respect to one specific bright line, and the half-width is widened for bright lines other than the specific bright line of the back light source.

Japanese Patent Application Laid-Open No. Hei 6-289379 discloses an invention relating to a method for manufacturing a liquid crystal display element.
For the purpose of preventing the transparent electrode pattern from being seen on the screen, the refractive index of the insulating layer mainly made of metal alkoxide is set to a value in the range of 1.6 to 1.7.

Further, Japanese Patent Application Laid-Open No. 6-194639 discloses an invention relating to a liquid crystal display panel. The purpose of the invention is to prevent the occurrence of interference fringes due to a difference in thickness between an insulating film and a liquid crystal layer. It is characterized in that the refractive index difference between adjacent insulating films, liquid crystal layers or substrates is set to a value of 0.2 or less.

[0011]

However, the three-dimensional display device disclosed in Japanese Patent Publication No. Hei 5-78017 and Japanese Patent Laid-Open Publication No. Sho 61-227498, or Japanese Patent Publication No. Hei 4-4.
In the color filter disclosed in JP-A-9928,
Light from a cathode ray tube as a light source causes multiple interference inside a liquid crystal element in a liquid crystal shutter, so that there is a problem that a viewing angle becomes narrow. That is, the liquid crystal element is composed of a liquid crystal layer sandwiched between a pair of substrates with transparent electrodes, and usually has an alignment film formed on the inner surface of the transparent substrate. Therefore, since there is an interface having a different refractive index, light incident on the liquid crystal element causes multiple interference inside the liquid crystal element, and as the viewing angle is increased, a phenomenon occurs in which the light transmittance and the luminance rapidly change. Will be.

In addition, the influence of multiple interference of light in a three-dimensional display device and a color liquid crystal shutter also affects the wavelength of light, and when light of a broad wavelength is used, a so-called "glare feeling" is noticeable. There is a property that there is no.
However, in order to improve the color purity and the like, when a light with a narrow wavelength range, particularly a narrow green wavelength is used, a sudden change in luminance or color occurs, which is recognized as a glare, The effect of multiple interference of light is severe. On the other hand, the multiple interference of light in a three-dimensional display device and a color liquid crystal shutter also affects the thickness of the liquid crystal element (liquid crystal cell thickness). There is a property that the change hardly occurs. This is because when a nematic liquid crystal is used, since the thickness of the liquid crystal element is usually 5 μm or more, even if multiple interference occurs, many peaks of the interference spectrum appear. However, it has been proposed to use a ferroelectric liquid crystal or an antiferroelectric liquid crystal in applications requiring high-speed response, for example, in a three-dimensional display device or a color liquid crystal shutter. In this case, the thickness of the liquid crystal element is increased. Is usually 3 μm or less, the number of peaks in the interference spectrum is small, and a sense of glare tends to occur.

A liquid crystal device using a ferroelectric liquid crystal disclosed in Japanese Patent Application Laid-Open No. Hei 2-13926 is capable of reducing the occurrence of multiple interference by adjusting the thickness of the transparent electrode and the thickness of the ferroelectric liquid crystal. Attempts to curb it were inadequate. In this regard, the relationship between the thickness of the liquid crystal layer (ferroelectric liquid crystal) and the degree of interference shown in FIG. 4 or the relationship between the thickness of the transparent electrode (ITO) and the degree of interference shown in FIG. It can be easily understood that merely adjusting the film thickness of the ferroelectric liquid crystal and the thickness of the ferroelectric liquid crystal is insufficient to obtain a low value of interference, that is, to suppress the occurrence of multiple interference.
Further, the liquid crystal device using the ferroelectric liquid crystal disclosed in the patent publication has a structural problem that a special phosphor light source must be used.

The liquid crystal display device having an insulating film disclosed in Japanese Patent Application Laid-Open No. 61-174511 can be obtained by adjusting the thickness of the transparent electrode and the thickness of the insulating film. The liquid crystal display device having a reflectance adjusting layer disclosed in Japanese Patent Application Laid-Open Publication No. H10-15095, by adjusting the refractive index of the reflectance adjusting layer, the liquid crystal layer and the transparent electrode layer, and the thickness of the reflectance adjusting layer and the transparent electrode layer. Each attempts to reduce the reflected light, but is insufficient. In this regard, the relationship between the thickness of the transparent electrode (ITO) and the degree of interference shown in FIG. 5 or the relationship between the thickness of the insulating film and the degree of interference shown in FIGS. It will be easily understood that a low value of the interference degree cannot be obtained only by adjusting the thickness and the thickness of the insulating film.

Further, JP-A-10-123522, JP-A-9-015657, and JP-A-7-168
No. 173, JP-A-6-289379, and JP-A-6-194639 disclose that the optical path length changes when the viewing angle is changed, and that multiple interference occurs. Therefore, when the viewing angle is greatly changed, there is a problem that a rapid change in color or luminance cannot be suppressed.

More specifically, JP-A-10-12352
In the liquid crystal display substrate disclosed in Japanese Patent Application Publication No. 2 (1993) -209, the thickness of the alignment film must be strictly controlled to a specified value or less, and it is difficult to form the alignment film uniformly, or The problem was that the orientation was low. Further, the liquid crystal display device disclosed in JP-A-9-015657 is
It is necessary to prepare two liquid crystal panels and strictly control and vary the thickness of the insulating film present in each liquid crystal panel, and it is difficult to uniformly form the insulating film in each liquid crystal panel. Was.

Further, in the liquid crystal display device disclosed in Japanese Patent Application Laid-Open No. 7-168173, it is necessary to change the thickness of the transparent electrode or the insulating film for each specific bright line of light, and the type of the light source is excessively limited. There was a problem that was. Further, in the method of manufacturing a liquid crystal display device disclosed in JP-A-6-289379, it is necessary to strictly control the refractive index of the insulating layer to a value within a predetermined range. In addition, there was a problem that the viewing angle was narrow. Further, in the liquid crystal display panel disclosed in Japanese Patent Application Laid-Open No. 6-194639, it is necessary to strictly control the refractive index difference between an adjacent insulating film, a liquid crystal layer, and a substrate within a predetermined range.
It is not easy to manufacture the liquid crystal display panel, and furthermore, there is a problem that the viewing angle is narrow.

As described above, the occurrence of multiple interference in a liquid crystal display device or the like is caused by the refractive index of the transparent electrode, the thickness of the transparent electrode, the refractive index of the liquid crystal layer, the thickness of the liquid crystal layer, the thickness of the insulating film, The refractive index of the insulating film and the like are complicatedly affected, and simply adjusting the respective values cannot suppress the occurrence of multiple interference. Then, the inventors of the present invention diligently studied the above problem, and as a result, introduced a concept of the interference degree (I) for the liquid crystal display device, and this interference degree (I) (hereinafter sometimes simply referred to as interference degree). ), The optical display device is configured to limit the value within a predetermined range.
It has been found that the influence of multiple interference can be reduced. Accordingly, it is an object of the present invention to provide an optical display device which has a small change in luminance and a sense of glare over a wide viewing angle, and is particularly suitable for a stereoscopic display device, a color liquid crystal shutter, and the like.

[0019]

According to the present invention, there is provided a liquid crystal device comprising a liquid crystal layer sandwiched between a pair of substrates with a transparent electrode;
An optical display device including a light source, wherein an angle (θ) of a light emitting direction with respect to a normal to a display surface of the liquid crystal element is 0 to 60 °.
In the case of, when each light transmittance measured at each measurement interval Δθ is T (θ), and the average value is T _ave , the interference degree (I) represented by the following equation (1) is obtained. From 0 to 0.
The value is set to a value within the range of 09.

[0020]

(Equation 2)

According to this structure, it is possible to provide an optical display device in which the influence of the multiple interference is reduced and the luminance change and the glare are small in a wide viewing angle.

In constructing the optical display device of the present invention, the maximum peak wavelength (λ) of light is set to 500 to 600.
Preferably, the value is in the range of nm. With this configuration, the control is performed with reference to the green light that most affects the interference (I) represented by Expression (1).
The effect of multiple interference can be further reduced. In addition,
According to the optical display device of the present invention, there is a characteristic that the influence can be reduced even under the condition of a narrow wavelength of a green system in which multiple interference is likely to occur.

Further, in configuring the optical display device of the present invention, an insulating film is provided on the surface of the transparent electrode, and the thickness (t1) of the insulating film is set to 0.2 to the maximum peak wavelength (λ) of light.
It is preferably 0.27 times. With this configuration, multiple interference caused by the insulating film can be effectively reduced.

In configuring the optical display device of the present invention, the refractive index (n1) of the insulating film is determined by the sum of the refractive index (n2) of the transparent electrode and the refractive index (n3) of the liquid crystal layer. It is preferable to set the value in the range of 1/3 to 2/3 of (n2 + n3). With such a configuration, there is a feature that multiple interference caused by each of the transparent electrode, the insulating film, and the liquid crystal layer can be effectively reduced.

In configuring the optical display device of the present invention, it is preferable that the distance between the pair of substrates with transparent electrodes is set to a value of 3 μm or less. With this configuration,
A thin optical display device can be provided. In addition,
According to the optical display device of the present invention, there is a feature that the influence can be reduced even under such a thin condition that multiple interference is likely to occur.

In constituting the optical display device of the present invention, it is preferable to use a ferroelectric liquid crystal or an antiferroelectric liquid crystal for the liquid crystal layer. With this configuration, it is possible to provide a high-speed response optical display device. In addition, according to the optical display device of the present invention, there is a feature that the influence can be reduced even when a liquid crystal material in which multiple interference easily occurs is used.

In constituting the optical display device of the present invention, a color liquid crystal comprising a neutral polarizing plate, a plurality of variable retardation plates for giving different retardations according to signal voltages, and a plurality of color polarizing plates. It is preferable to include a shutter. With this configuration, multiple interference of light on the variable retardation plate can be effectively prevented, and a clear color image can be recognized.

Further, in constituting the optical display device of the present invention, the light source is a scanning type video output means for displaying a left-eye image and a right-eye image in a time-division manner and alternately displaying the same for each frame period. And the polarizing plate are liquid crystal optical switch means for switching the polarization state in synchronization with the switching of the left eye image and the right eye image, and further transmit the transmitted light for the left eye image transmitted through the liquid crystal optical switch means with the left eye. It is preferable to include eyeglass means capable of selectively visually recognizing the transmitted light for the right eye image with the right eye. With this configuration, while effectively preventing multiple interference caused by the light of the left-eye image and the right-eye image emitted from the scanning video output unit,
A clear stereoscopic image can be recognized.

[0029]

Embodiments of the present invention will be described below with reference to the drawings. It should be noted that the drawings to be referred to show the size of each component so that the present invention can be understood,
It merely shows the shape and arrangement.
Therefore, the present invention is not limited only to the illustrated example. In the drawings, hatching representing a cross section may be omitted.

[First Embodiment] In a first embodiment, as shown in FIG. 9, a light source 80, a first polarizing plate 68, a first transparent substrate 64, and a first transparent electrode 62 are provided. , A first insulating film 60, a liquid crystal layer 58, a second insulating film 56,
Optical display device 50 in which a transparent electrode 54, a second transparent substrate 52, and a second polarizing plate 70 are sequentially laminated.
It is.

(1) Light Source Light sources include a backlight used in a liquid crystal display, a three-wavelength fluorescent tube, a CRT, an EL display, and a PD.
P and the like. These light sources can be appropriately selected depending on the purpose of use. For example, when information is displayed using a dot matrix liquid crystal element, it is preferable to use a light source that emits light simultaneously in a plane. In the case of a three-dimensional display device using a liquid crystal shutter, a light source capable of sequentially switching and displaying a left-eye image and a right-eye image is preferable.
T, EL display, PDP and the like.

(2) Liquid crystal element In the first embodiment, the first transparent substrate 6 shown in FIG.
4, a first transparent electrode 62, a first insulating film 60, a liquid crystal layer 58, a second insulating film 56, and a second transparent electrode 54.
And the second transparent substrate 52, the liquid crystal element 6
No. 6. However, although not shown, the liquid crystal element 66 preferably includes a color filter, an alignment film, a flattening film, a TFT layer, and the like.

Transparent Substrate As the types of the first and second transparent substrates, substrates made of known materials such as glass and plastic used for liquid crystal elements can be used. More specifically, examples of the glass include soda glass and quartz glass. In addition, plastics include polyether sulfone (PES), polycarbonate (PC), polyarylate (PAr), polyethylene terephthalate (PET),
Polyester (PE) and the like can be mentioned. Also, the thickness of these transparent substrates is not particularly limited, but is preferably, for example, a value in the range of 50 μm to 10 mm, and more preferably 80 μm to 2 m.
It is a value within the range of m.

Transparent Electrodes The types of the first and second transparent electrodes are not particularly limited. For example, ITO, ATO, ZnO
And the like. Also, the thickness of these transparent electrodes is determined in consideration of the interference (I) as shown in FIG.
The value is preferably in the range of 1 to 0.30 μm.
The reason for this is that when the thickness of the transparent electrode is less than 0.01 μm, the resistance value increases, and when switching is performed at high speed, heat is easily generated. On the other hand, the thickness of the transparent electrode is 0.30 μm. Exceeds, the light transmittance decreases,
Alternatively, it may take time to form a film, or it may be difficult to adjust the degree of interference. Therefore,
The value is more preferably in the range of 0.02 to 0.25 μm, and even more preferably in the range of 0.03 to 0.20 μm. However, as described above, for example, when the interference degree shown in FIG. 5 is taken into consideration, in the case of the samples 15 to 20 in Table 2, the thickness of the transparent electrode is finally set to 0.1.
It must be 03 ± 0.001 μm, 0.15 ± 0.001 μm, or 0.23 ± 0.001 μm.

Insulating film Further, for the purpose of preventing a short circuit between the transparent electrodes facing each other or stabilizing the orientation of the liquid crystal,
It is preferable to form first and second insulating films (including an alignment film) on the first and second transparent electrodes, respectively. As such an insulating film material, a polyimide resin, an acrylic resin, a silicone resin, an epoxy resin, a polyethersulfone resin, a polycarbonate resin, a polyarylate resin, a polyester resin, or the like alone or A combination of two or more types is exemplified. Among these, in particular, the silicone resin has excellent adhesion to the transparent electrode, has high transparency, and further has a high refractive index by using an additive such as an alkoxysilane compound or an alkoxytitanium compound, or silica particles. This is preferable because the value can be changed widely, and as a result, the adjustment of the interference degree becomes easy.

The thickness of these insulating films is as follows.
Although it is specifically determined in consideration of the degree of interference as shown in FIGS. 6 and 7, for example, it is preferably a value in the range of 0.01 to 0.5 μm. The reason for this is that when the thickness of the insulating film is less than 0.01 μm, the electrical insulation and mechanical strength may be significantly reduced, while
If the thickness of the insulating film exceeds 0.5 μm, the light transmittance may decrease, or it may be difficult to adjust the degree of interference. Therefore, the thickness of the insulating film is set to 0.04 to
More preferably, the value is in the range of 0.20 μm,
More preferably, the value is in the range of 0.05 to 0.15 μm. However, as described above, FIGS.
When the thickness of the insulating film is determined in consideration of the degree of interference shown in Table 3,
In the case of Samples 21 to 60 in Table 7, the thickness of the insulating film is set to a value in the range of 0.06 to 0.15 μm, and in the case of Samples 61 to 100 in Tables 8 to 12, The thickness of the film will be in the range of 0.1 to 0.18 μm.

Liquid Crystal Layer The type of liquid crystal constituting the liquid crystal layer can be appropriately selected from nematic liquid crystal, ferroelectric liquid crystal, antiferroelectric liquid crystal, and the like. For example, as the ferroelectric liquid crystal, (meth) acrylate main chain polymer liquid crystal, chloroacrylate main chain polymer liquid crystal, siloxane main chain polymer liquid crystal, oxirane main chain polymer liquid crystal, siloxane-olefin main chain Introduces ring substituents such as polymer liquid crystals, Schiff base ferroelectric low molecular liquid crystals, azo and azoxy ferroelectric low molecular liquid crystals, biphenyl and aromatic ester ferroelectric low molecular liquid crystals, halogens, cyano groups, etc. One or a combination of two or more of such ferroelectric low-molecular liquid crystals and ferroelectric low-molecular liquid crystals having a heterocyclic ring. Also,
A ferroelectric liquid crystal obtained by adding a chiral dopant to a phenylpyridine-based base liquid crystal is preferable because the helical pitch can be easily adjusted. Examples of such a phenylpyridine-based base liquid crystal and chiral dopant are shown below.

[0038]

Embedded image

[0039]

Embedded image

As the antiferroelectric liquid crystal, a polymer liquid crystal represented by the following formula can be exemplified.

[0041]

Embedded image

However, more preferably, the above-mentioned ferroelectric liquid crystal or antiferroelectric liquid crystal is used for the liquid crystal layer, and the thickness is 3 μm or less. Generally, when the thickness of the liquid crystal layer exceeds 3 μm, interference of visible light hardly occurs. However, in the liquid crystal display device of the first embodiment, the influence can be effectively prevented even if the liquid crystal material in which multiple interference is easily generated is used and the thickness is reduced. Further, by using a ferroelectric liquid crystal or an antiferroelectric liquid crystal, a liquid crystal display device which can respond at high speed can be provided.

(3) Polarizing Plate The first and second polarizing plates may be appropriately selected from among commercially available neutral polarizing plates and color polarizing plates according to the desired display color and used. it can. In addition, it is preferable that these polarizing plates are bonded to the outer surface of the transparent substrate sandwiching the liquid crystal layer with an adhesive made of acrylic resin or the like. Thereby, multiple interference at the interface between the polarizing plate and the transparent substrate can be prevented, and so-called Newton's ring can be effectively prevented.

The method of arranging the polarizing plate can be variously changed according to the purpose and use of the liquid crystal display device. For example, in the liquid crystal display device 50 shown in FIG.
When a backlight that emits light uniformly in a plane is used and a dot matrix liquid crystal element is used as the liquid crystal element 66,
A first polarizing plate 68 is provided on the outer surface 63 of the first transparent substrate 64, and a second polarizing plate 68 is provided on the outer surface 71 of the second transparent substrate 52.
It is preferable to arrange the respective polarizing plates 70. In this case, although not shown, the first and second polarizing plates 68, 7
0 and the first and second transparent substrates 64 and 52, a color filter for color display and a phase difference plate for compensating display colors are provided for each dot (not shown). It is more preferable to arrange them.

Further, as shown in FIG.
However, in the case of the liquid crystal shutter 1 for stereoscopic display which is used by being arranged on the front of the CRT 10, it is preferable to arrange the polarizing plate 12 on only one side of the liquid crystal element 14. In that case,
It is preferable to attach still another polarizing plate 24, 26 to the glasses worn by the observer. The liquid crystal shutter 1 shown in FIG. 10 will be described in further detail in a second embodiment described later.

Further, as shown in FIG. 12, a neutral polarizer 91, a plurality of liquid crystal elements 96 and 97, and color polarizers 92 to 95 are combined to change the color transmitted per time and display the color. A liquid crystal shutter may be configured. The color liquid crystal shutter shown in FIG. 12 will be described in further detail in a third embodiment described later.

(4) Interference The first embodiment is characterized in that the interference (I) defined by the above equation (1) is set to a value within the range of 0 to 0.09. This interference degree will be described with reference to FIGS. 1 to 3 and FIG.

First, FIG. 1 is a diagram showing the relationship between the degree of interference (-) defined by the equation (1) and the luminance (nit).
2 and 3 are diagrams showing the relationship between the viewing angle (°) and the light transmittance (relative value) or luminance (nit), respectively. FIG. 11 is a diagram illustrating a method for measuring the light transmittance. FIG.

In FIG. 1, the abscissa indicates the degree of interference (-) defined by the equation (1), and the ordinate indicates the luminance (nit). The viewing angles are 30, 35, and 40 °.
Shows these relationships. The luminance was measured at these viewing angles as shown in FIGS.
As can be understood from FIG. 2, multiple interference occurs near the viewing angle of 30 to 40 °, and the value of the light transmittance greatly changes.

The viewing angle corresponds to the angle (θ: 0 to 60 °) of the light emission direction when the light transmittance is measured by a photometer. As shown in FIG. Liquid crystal element 6
6 is a value defined by a measurement angle with respect to a normal 82 on the display surface 71 of FIG. For example, at point A in FIG.
The angle (θ) of the light emission direction because it is on the normal line 82
Is 0 °, and if it is point C, it is 60 ° with respect to the normal 82.
Since the position is shifted, the angle (θ) of the light emission direction is 60.
°. Then, when the viewing angle, that is, the angle (θ) of the light emitting direction is in the range of 0 to 60 °, the position S at the measurement interval of Δθ and equidistant from the point D in FIG.
(For example, 60 cm), each light transmittance T (θ) is measured by a spectral transmittance meter, and the average value T _ave and the interference degree (I) can be calculated from the measured values.

In calculating the interference (I) defined by the equation (1), the value of Δθ, which is the value of the measurement interval, is multiplied. This is because the values of) vary. However, since the value of the degree of interference (I) becomes more uniform, the measurement interval of Δθ is set to a value within 3 °, and more preferably to a value within 1 °. The reason why the angle (θ) in the emission direction of light for measuring the light transmittance T (θ) is set to 0 to 60 ° is 60 °.
When the viewing angle exceeds, the optical path length of the light transmitted through the liquid crystal element becomes longer, so that the transmittance becomes smaller, and even if multiple interference occurs, there is little glare. Further, the light used for measuring the light transmittance T (θ) has a maximum peak wavelength of 500 to 600 nm.
It is more preferable to use light in the range described above, and it is even more preferable to use the light having a predetermined wavelength extracted by a spectroscope. The reason is that the maximum peak wavelength is 500-600.
The light in the nm range is a green light, and the light having a wavelength in this range has a property that the human eye has high sensitivity. This is because by setting the degree (I), a clearer image with higher luminance can be obtained as a result.

FIG. 8 shows the relationship between the wavelength (nm) and the visibility (-). As is easily understood from FIG. 8, the luminosity plots a parabola having a peak at a wavelength of about 555 nm, and has a wavelength of about 700 nm and a wavelength of about 40 nm.
At about 0 nm, the value of the visibility decreases to zero. However, when the wavelength exceeds 600 nm or when the wavelength is less than 500 nm, the value of the visibility becomes 0.5 or less. Therefore, if the interference degree is defined as (I) in such a range, the sense of glare is substantially not a problem, and the meaning of preventing multiple interference is reduced.

Then, as shown in FIG.
The smaller the value of the degree of interference (I) defined by is, the higher the value of the brightness tends to be obtained, and the smaller the value of the degree of interference (I), the more the brightness at the viewing angles of 30, 35 and 40 ° Are also small. Therefore, if the degree of interference (I) is 0.09 or less, the viewing angles 30 and 3
65 (nit) at both 5 and 40 °
The above high luminance value can be obtained. That is, in the first embodiment, by setting the interference degree (I) defined by the equation (1) to a value within the range of 0 to 0.09,
More preferably, the value is in the range of 0 to 0.08, and even more preferably, the value is in the range of 0 to 0.07. Obtainable.

In order to adjust the degree of interference (I) to a value within the above-mentioned range, the type of the transparent electrode and the type of the transparent electrode are measured while appropriately measuring the value of the degree of interference (I). Electrode refractive index, transparent electrode thickness, liquid crystal layer type, liquid crystal layer refractive index, liquid crystal layer thickness, insulating film type, insulating film thickness,
It may be adjusted by combining the refractive index of the insulating film and the like. However, considering the required performance of the liquid crystal element such as the required liquid crystal display area, response time, and contrast performance, the type of the transparent electrode, the refractive index of the transparent electrode, the thickness of the transparent electrode, the type of the liquid crystal layer, the refraction of the liquid crystal layer, The ratio, the thickness of the liquid crystal layer, and the like may be practically limited. Then, the interference degree (I)
In order to effectively adjust the value to a value within a predetermined range, it is more preferable to provide an insulating film and optimize the type of the insulating film, the refractive index of the insulating film, and the thickness of the insulating film.

For example, when the insulating film is made of a silicone-based material, the refractive index of the insulating film and the thickness of the insulating film can be easily adjusted, and as a result, the value of the degree of interference (I) can be easily adjusted. . Further, by setting the thickness (t1) of the insulating film to a value of 0.2 to 0.27 times the maximum peak wavelength (λ) of light, the value of the degree of interference (I) can be more easily adjusted. Become. For example, when the maximum peak wavelength (λ) of light is 540 nm, the thickness (t1) of the insulating film is preferably set to a value in the range of 108 to 146 nm. Further, the refractive index (n1) of the insulating film is set to be 1/3 to 2/2 of the total value (n2 + n3) of the refractive index (n2) of the transparent electrode and the refractive index (n3) of the liquid crystal layer.
By setting the value to 3, more preferably 2/5 to 3 /
By setting the value to 5, the allowable width of the thickness of the liquid crystal layer is widened, and the adjustment of the value of the degree of interference (I) is further facilitated.

Here, the relationship between the thickness of the insulating film, the refractive index, and the degree of interference will be described in detail with reference to FIGS. 6 and 7. FIG. FIG. 6 corresponds to samples 21 to 60 in Tables 3 to 7, and FIG.
This corresponds to 1 to 100. Each of the insulating films is made of a silicone-based material, and the refractive index of the insulating film is 1.48 by changing the addition amount of the alkoxy titanium compound.
~ 1.70. For example, sample 21
６０60, the refractive index of the insulating film is set to a value of 1.6 or more, and the thickness of the insulating film is set to 0.05〜0.15.
By setting the value in the range of μm, the value of the degree of interference (I) can be set to 0.09 or less. Sample 6
In the case of 1 to 100, the refractive index of the insulating film is set to a value of 1.6 or more and the thickness of the insulating film is set to 0.08 to 0.
By setting the value within the range of 18 μm, the interference degree (I)
Can be 0.09 or less.

[Second Embodiment] In a second embodiment, as shown in FIG. 10, a scanning type video output means 10 for displaying a left-eye image and a right-eye image in a time-division manner and alternately displaying each frame period. , A polarizing plate 12 and liquid crystal optical switch means 14 for switching the polarization state in synchronization with switching between the left-eye image and the right-eye image are sequentially provided.
The transmitted light for the left eye image transmitted through the polarizing plate 12 and the liquid crystal element 14 is transmitted to the left eye and the right eye image using spectacles (may be referred to as polarized spectacles 24 and 26) provided with the light source 4 and the light source 26. It is a three-dimensional display device 1 in which transmitted light for use can be selectively visually recognized by the right eye. The liquid crystal optical switch means 14
Can have the same configuration as the crystal element in the first embodiment.

(1) Scanning Video Output Means The scanning video output means 10 shown in FIG. 10 corresponds to the light source shown in FIG. 9, but the type thereof is not particularly limited. PDPs, ELs, LEDs, projectors, and the like. However, since the left-eye image and the right-eye image are alternately displayed, high-speed switching of the images is possible, and the scanning-type video output unit uses, for example, a frame frequency of 100 Hz or more so as to obtain a clear stereoscopic image. Certain CRTs are more preferred.

(2) Liquid crystal optical switch means The liquid crystal optical switch means 14 (sometimes referred to as a liquid crystal shutter) shown in FIG.
The polarization state of the liquid crystal is switched by changing the value of the applied voltage and the like (on / off) in synchronization with the display timing of the left-eye image and the right-eye image in, and the left-eye image and the right-eye image are transmitted respectively. Alternatively, it is made non-transmissible. Note that the same type and configuration of the liquid crystal used for the liquid crystal optical switch means 14 as in the first embodiment can be used.

(3) Polarized Glasses Polarized glasses 24 and 26 shown in FIG. 10 are composed of, for example, a left-eye filter and a right-eye filter as λ / 4 plates having mutually different polarization characteristics. The left-eye filter has a polarization axis that matches (parallel) the polarization of the left-eye image, and the right-eye filter has a polarization axis that matches (parallel) the polarization of the right-eye image. are doing. Therefore, it is possible to selectively visually recognize the transmitted light for the left eye image transmitted through the polarizing plate 12 and the liquid crystal optical switch means 14 with the left eye and the transmitted light for the right eye image with the right eye.

The polarizing glasses 24 and 26 may be constructed not only with glasses but also with goggles and helmets incorporating a filter for the left eye and a filter for the right eye having different polarization characteristics from each other. In addition, a polarization switching mechanism (not shown)
Between the scanning type video output means 10 and the liquid crystal optical switch means 14, or between the liquid crystal optical switch means 14 and the polarizing glasses 2
It is also preferable that one of the left-eye image and the right-eye image be linearly polarized light and the other be circularly polarized light (elliptically polarized light). In that case, polarized glasses 2
The polarization axes of the left-eye filter and the right-eye filter of Nos. 4 and 26 are set in the orthogonal direction with respect to the linearly polarized light, and the elliptically polarized light is set in front of the left-eye filter and the right-eye filter. It is preferable to provide a phase difference plate for compensating the above. By configuring the polarizing glasses 24 and 26 in this manner, while one of the left eye image and the right eye image is linearly polarized light, the other is circularly polarized light (elliptically polarized light). Can be improved.

[Third Embodiment] A third embodiment relates to a field sequential color display device.
It includes the color liquid crystal shutter shown in FIG. This color liquid crystal shutter includes a neutral polarizing plate 91,
A first liquid crystal element (which may be referred to as a variable retardation plate) 97 that provides different retardations according to signal voltages, and first and second liquid crystals that correspond to different emission colors.
Color polarizers 92 and 93, and a second liquid crystal cell 96 that provides further different retardation according to the signal voltage;
Further, it comprises third and fourth color polarizers 94 and 95 corresponding to different emission colors.

Although not shown, a field-sequential color display device is constituted by providing an image display, a synchronizing circuit, or a control circuit as a light source. Therefore, the white light emitted from the light source in the predetermined frame period is divided into the first and second light whose polarization state is controlled by the operation of the synchronization circuit and the control circuit.
Are transmitted light or non-transmitted light in the liquid crystal element, and the transmitted light passes through a plurality of color polarizers to make a color image visible. Hereinafter, the main part of the color display device will be mainly described.

(1) Neutral Polarizing Plate A neutral polarizing plate is defined as a polarizing plate that extracts a linearly polarized light portion from white light in a visible light region emitted from a light source. For example, a triacetyl cellulose (TAC) film, A polyvinyl alcohol film impregnated with iodine or a dichroic dye may be formed on a polyester film, or a dichroic dye may be dispersed in a polyester film and then stretched. Further, in order to improve visibility and durability, it is also preferable to perform an anti-glare treatment or an anti-reflection treatment on the surface of the neutral polarizing plate.

(2) Liquid Crystal Element A liquid crystal element has a function as a variable retardation plate, and is defined as an element that takes a different polarization state according to a signal voltage and retards transmitted light. This liquid crystal element can be composed of, for example, as shown in FIG. 12, a pair of transparent substrates with transparent electrodes 31, 32, 33, 34, respectively, and liquid crystal materials 41, 42 sandwiched therebetween. The type of liquid crystal used is not particularly limited. For example, at least one selected from the group consisting of a ferroelectric liquid crystal, a chiral smectic A liquid crystal exhibiting an electric field-induced tilt, and an antiferroelectric liquid crystal. It is preferably a liquid crystal. Compounds obtained by adding a non-liquid crystalline polymer to these liquid crystals are also preferable.

(3) Color Polarizing Plate The color polarizing plate can have basically the same configuration as the above-described neutral polarizing plate. However, depending on the type of dichroic dye to be added, a yellow polarizing plate or a blue polarizing plate is used. , A red polarizing plate, a cyan polarizing plate, a violet polarizing plate, a green polarizing plate, and the like. The arrangement of the color polarizer is not particularly limited as long as the transmitted light of the liquid crystal element is incident thereon and the light can be polarized in a predetermined direction. As described above, the first to fourth color polarizing plates (yellow, blue,
Red, cyan), and when a neutral polarizer and first and second liquid crystal elements are also arranged, neutral polarizer / first liquid crystal element / first color polarizer (yellow) / second color Polarizing plate (blue) / second
Liquid crystal element / third color polarizing plate (red) / fourth color polarizing plate (cyan). Although not shown, when the first to third color polarizers (blue, red, and green) are used, and the neutral polarizer and the first to third liquid crystal elements are also arranged, the neutral polarizer / second 1st liquid crystal element / 1st
It is preferable to sequentially arrange the following color polarizer (blue) / second liquid crystal element / second color polarizer (red) / third liquid crystal element / third color polarizer (green).

[0067]

Embodiments of the present invention will be described below in more detail. However, needless to say, the scope of the present invention is not limited to the description of the examples.

Example 1 (1) Preparation of Liquid Crystal Element An amino group-containing siloxane oligomer was placed in a mixing vessel.
The glycidyl group-containing siloxane oligomer and the trialkoxysilane compound were each used in a weight ratio of 1: 1: 1. Then, oxalic acid was added as a catalyst for the condensation reaction in an amount of 0.1 to 100 parts by weight of the trialkoxysilane compound.
The solution was added in an amount of 01 parts by weight, and ethanol was further added to prepare an insulating film solution. On the other hand, a polyethersulfone (PES) substrate having a thickness of 0.1 mm (FST manufactured by Sumitomo Bakelite) was used as the substrate, and ITO having a refractive index of 1.90 was formed on the surface of the substrate so as to have a thickness of 0.03 μm. Vapor deposition was performed to prepare a substrate with a transparent electrode.

Next, a solution for an insulating film was coated on the substrate with a transparent electrode using a gravure coater. This is 120
Heat treatment was performed at 30 ° C. for 30 minutes to form an insulating film having a thickness of 0.12 μm on the transparent electrode. In addition, three substrates with the transparent electrodes on which the insulating films were formed were prepared, and one of them was used to measure the refractive index of only the insulating films. Specifically, using an ellipsometer:
A value of 48 was obtained.

Next, a substrate with a transparent electrode on which two insulating films are formed is opposed to each other with a predetermined gap provided, and liquid crystal is injected into the gap to form a liquid crystal layer having a thickness of 1.9 μm. The liquid crystal device of Sample 1 was used. The liquid crystal used was a ferroelectric polymer liquid crystal A (manufactured by Idemitsu Kosan Co., Ltd.), a ferroelectric low molecular liquid crystal B (manufactured by Idemitsu Kosan Co., Ltd.), and a low molecular liquid crystal having the following structural formulas. C (Midori Chemical Co., Ltd.)
And low-molecular liquid crystal D (manufactured by Midori Kagaku Co., Ltd.) were prepared by mixing at a weight ratio of 5: 3: 1: 1. Then, when the refractive index of the liquid crystal was measured using an ellipsometer, the ordinary refractive index (n _o) is 1.45, the extraordinary refractive index (n _e) is a value of 1.55 was obtained, respectively.
Also, simply the term refractive index of the liquid crystal, means the average value between the ordinary refractive index (n _o) and extraordinary refractive index (n _e).
Therefore, the refractive index in the case of this liquid crystal is 1.50.

[0071]

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(2) Measurement of Degree of Interference Under the condition of a temperature of 25 ° C., light emitted from a white light source having a beam diameter of 2 mm was introduced into a spectroscope (manufactured by JASCO Corporation), and a wavelength of 5
40 nm light was split. The split light having a wavelength of 540 nm was incident on Sample 1, and the transmitted light intensity was measured using a photomultiplier tube (manufactured by Hamamatsu Photonics KK). And
The light transmittance of the sample 1 was calculated from the ratio of the transmitted light intensity in a state where the sample 1 was not installed (this intensity is set to 1) and the transmitted light intensity in a state where the sample 1 was installed. Further, as an angle (θ) of the light emission direction with respect to the normal line of the liquid crystal element, Δθ is 1 ° within a range of 0 ° to 60 °.
The light transmittance of sample 1 is changed to T by sequentially changing the angle.
(Θ) was measured. Next, the obtained light transmittance T (θ)
Was further calculated from the data of (1). Table 1 shows the obtained results such as the degree of interference (I).

[Examples 2 to 9 and Comparative Examples 1 to 5] Samples 2 to 14 of liquid crystal elements were prepared in the same manner as in Example 1 except that the thickness of the liquid crystal layer and the like were changed as shown in Table 1. And the degree of interference (I) were measured. The obtained results such as the degree of interference (I) are shown in Table 1 and FIG. In Table 1, the examples are represented by EX and the comparative examples are represented by CE, and the unit of each film thickness is μm.
The value of each refractive index, the value of T _ave , and the value of the degree of interference (I) are dimensionless (−). Hereinafter, the same applies.

Examples 10 to 12 and Comparative Examples 6 to 8 Example 1 was repeated except that the thickness of the transparent electrode was changed as shown in Table 1.
Samples 15 to 20 of the liquid crystal element were prepared in the same manner as in the above, and the interference (I) was measured. The results of the obtained interference degree (I) and the like are shown in Table 2 and FIG.

[Examples 13 to 49, Comparative examples 9 to 51] Samples 21 to 100 of liquid crystal elements were manufactured in the same manner as in Example 1 except that the thickness of the insulating film and the like were changed as shown in Table 1. ,
The degree of interference (I) was measured. The obtained results such as the degree of interference (I) are shown in Tables 3 to 12 and FIGS.

[0079]

[Table 1]

[0080]

[Table 2]

[0081]

[Table 3]

[0082]

[Table 4]

[0083]

[Table 5]

[0084]

[Table 6]

[0085]

[Table 7]

[0086]

[Table 8]

[0087]

[Table 9]

[0088]

[Table 10]

[0089]

[Table 11]

[0090]

[Table 12]

Example 50 A liquid crystal device having the same structure as in Example 1 was manufactured. Next, a neutral polarizing plate LLC2-9218 (Sunlitz Co., Ltd.) having a size of 300 mm in length and 400 mm in width is provided on the light emitting surface side of a color CRT (scanning image output means) having a maximum wavelength peak at 540 nm.
) And the liquid crystal element (optical switch means) were sequentially arranged to form a three-dimensional image display device. Further, the image signal source input to the color CRT and the signal source to the liquid crystal element were connected by a synchronous circuit. Therefore, the color C
In RT, the left-eye image and the right-eye image are time-divided and alternately displayed for each frame period, and the polarization state of the liquid crystal element can be switched in synchronization with the switching of the left-eye image and the right-eye image. Configured. Also,
The polarization characteristics of a left-eye filter and a right-eye filter having different polarization characteristics were prepared, but the polarization axes of the left-eye filter and the right-eye filter were changed to the left-eye image and the right-eye image, respectively. Were arranged so as to coincide with the polarized light.

Next, on a CRT, on a black background,
A white circle 1 having a diameter of 2 cm as the left-eye image and a white circle 2 having a diameter of 2 cm as the right-eye image are obtained by setting the distance between the centers of the circles to 5
cm, and alternately displayed at a cycle of 120 Hz (frame period 8.33 ms), and a predetermined voltage was alternately switched and applied between the electrodes of the liquid crystal element in synchronization with the display. As a result, a wide viewing angle (0 to 60)
°), a stereoscopic image was obtained with high luminance, and no so-called glare was observed.

Example 51 Two sets of liquid crystal elements (first and second liquid crystal elements) configured in the same manner as in Example 1 were produced. Next, a black and white CRT having a maximum wavelength peak at 540 nm and a neutral polarizer SKN-18243
(Polatechno, hereinafter the same), a first liquid crystal element,
Yellow polarizing plate Y1-18288 and cyan polarizing plate B2
-18265, a second liquid crystal element, and a red polarizer R-
18255 and a blue polarizing plate V2-18288 were sequentially arranged to produce a field sequential color display. When the display operation of the color display was confirmed, a color image was obtained with high luminance at a wide viewing angle (0 to 60 °), and no so-called glare was observed. At the center of the light emitting surface of the color display, only a 2 cm square area is displayed in green, and the light emission luminance is measured with a luminance meter CS-10.
0 (manufactured by Minolta Co., Ltd.) was measured at 60 cm from the light emitting surface. The results are shown in FIG. Viewing angle 0
In the range of ６０60 °, as the viewing angle increases, the luminance gradually decreases, but tends to change almost continuously.

[Comparative Example 52] A field sequential type color display was manufactured in the same manner as in Example 51 except that the liquid crystal element manufactured in Comparative Example 1 was used instead of the liquid crystal element manufactured in Example 1. . Then, when the display operation of the color display was confirmed, a so-called glare was observed, particularly in a green display. Further, in the same manner as in Example 51, the light emission luminance was measured using a luminance meter CS-100. Fig. 3 shows the results.
Shown in Also in Comparative Example 52, in the range of the viewing angle of 0 to 60 °, as the viewing angle increases, the brightness tends to gradually decrease, but the viewing angle at which the brightness changes greatly suddenly,
For example, it was confirmed that there was a viewing angle region of 30 to 40 °. Further, it was confirmed that the value of the light emission luminance itself of Comparative Example 52 was smaller than that of Example 51.

[0095]

According to the optical display device of the present invention, by controlling the degree of interference (I) represented by the equation (1) to a value within a predetermined range, the influence of multiple interference in a wide range of viewing angles can be obtained. Thus, it is possible to provide an optical display device suitable for a stereoscopic display device, a liquid crystal shutter, and the like, in which brightness change and glare are small.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a relationship between an interference degree and luminance.

FIG. 2 is a diagram illustrating a relationship between a viewing angle and light transmittance.

FIG. 3 is a diagram illustrating a relationship between a viewing angle and luminance.

FIG. 4 is a diagram showing the relationship between the thickness of a liquid crystal and the degree of interference.

FIG. 5 is a diagram showing the relationship between the thickness of ITO and the degree of interference.

FIG. 6 is a diagram illustrating a relationship between the thickness of an insulating film and the degree of interference (part 1).

FIG. 7 is a diagram illustrating a relationship between the thickness of an insulating film and the degree of interference (part 2).

FIG. 8 is a diagram illustrating a relationship between wavelength and visibility.

FIG. 9 is a sectional view of an optical display device.

FIG. 10 is a diagram illustrating a stereoscopic display device.

FIG. 11 is a diagram provided for explaining a method of measuring light transmittance.

FIG. 12 is a diagram showing a field sequential type color display.

[Explanation of symbols]

 Reference Signs List 1 stereoscopic display device 10 scanning image output means 12, 68, 70 polarizing plate 14 liquid crystal optical switch means (liquid crystal element) 16 retardation plate 24, 26 polarizing glasses (polarizing plate) 50 optical display device 52, 64 transparent substrate 54 , 62 Transparent electrodes 56, 60 Insulating film 58 Liquid crystal layer 66 Liquid crystal element 80 Light source 91 Neutral polarizer 92-95 Color polarizer 96, 97 Liquid crystal element

Continued on the front page F term (reference) 2H088 EA05 EA07 EA40 HA12 HA19 JA17 JA20 KA05 KA07 MA01 MA04 MA07 5C094 AA03 AA13 BA43 BA49 CA24 ED00 ED14 HA10 JA08 JA09 JA11 5G435 AA01 BB12 CC11 DD11 GG01 GG14

Claims (8)

[Claims] 1. An optical display device comprising: a liquid crystal element comprising a liquid crystal layer sandwiched between a pair of substrates with transparent electrodes; a polarizing plate provided on the surface of the substrate; and a light source. Angle of light emission direction with respect to normal (θ)
Is 0 to 60 °, each light transmittance measured at each measurement interval Δθ is T (θ), and the average value is T (θ).
An optical display device wherein, when _ave is set, the interference degree (I) represented by the following equation (1) is set to a value within a range of 0 to 0.09. (Equation 1) 2. The optical display device according to claim 1, wherein the maximum wavelength peak (λ) of the light is 500 to 600 n.
An optical display device having a value within the range of m. 3. The optical display device according to claim 1, wherein an insulating film is provided on a surface of the transparent electrode, and a thickness (t1) of the insulating film is set to a maximum wavelength peak (λ) of the light.
An optical display device characterized in that the value is 0.2 to 0.27 times of the above. 4. The optical display device according to claim 3, wherein a refractive index (n1) of the insulating film is a sum of a refractive index (n2) of the transparent electrode and a refractive index (n3) of the liquid crystal layer. An optical display device characterized in that the value is in the range of 1/3 to 2/3 of the value (n2 + n3). 5. The optical display device according to claim 1, wherein a distance between said pair of transparent electrode-equipped substrates is 3 μm or less. . 6. The optical display device according to claim 1, wherein a ferroelectric liquid crystal or an antiferroelectric liquid crystal is used for the liquid crystal layer. Display device. 7. The optical display device according to claim 1, wherein the optical display device includes a neutral polarizing plate, a plurality of variable retardation plates that provide different retardations according to a signal voltage, and a plurality of color polarizing plates. An optical display device comprising: a color liquid crystal shutter constituted by: 8. The optical display device according to claim 1, wherein the light source is a scanning type that time-divides a left-eye image and a right-eye image and alternately displays the left-eye image and the right-eye image for each frame period. Video output means, the liquid crystal element and the polarizing plate are liquid crystal optical switch means for switching the polarization state in synchronization with switching between the left eye image and the right eye image, and further transmitted through the liquid crystal optical switch means An optical display device, comprising: spectacle means capable of selectively recognizing transmitted light for a left eye image with a left eye and transmitted light for a right eye image with a right eye.