JPH11174489A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display device which is arbitrarily changeable over to a wide visual field angle characteristic and a narrow visual field angle characteristic according to a use form. SOLUTION: The liquid crystal element 19 for phase difference control of the liquid crystal display device including at least a liquid crystal element 10 for display and the liquid crystal element 19 for phase difference control consists of the constitution of any among, firstly, cholesteric liquid crystals 15 or chiral nematic liquid crystals 15 which are held between substrates 11 and 18 having electrodes 12 to 17 on the inside surfaces and are subjected to planar alignment or, secondly, the nematic liquid crystals 15 which are held between the substrates 11 and 18 having electrodes the 12 to 17 on the inside surfaces, are isotropic at the time of using the liquid crystal display device and are perpendicularly aligned by voltage impression or, thirdly, the nematic liquid crystals 15 which are held between the substrates 11 and 18 having the electrodes 12 to 17 on the inside surfaces and are randomly aligned.

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 capable of arbitrarily setting a viewing angle characteristic according to a use mode.

[0002]

2. Description of the Related Art Liquid crystal display devices are thin, lightweight, and low power consumption display devices, and are widely used in image display devices such as televisions and videos, and in OA equipment such as monitors, word processors, and personal computers.

Conventionally, for example, a twisted nematic (TN) using a nematic liquid crystal as a liquid crystal display element.
Mode liquid crystal display elements have been put to practical use, but have drawbacks such as slow response and a narrow viewing angle.

In order to solve the problem of the viewing angle, an alignment division method, a pixel division method, an IPS (in-plane switching) mode, a method using a vertical alignment mode, or a method combining these methods with a film phase plate is used. As a result, a great improvement has been made, and a wide viewing angle liquid crystal display device having a viewing angle characteristic of 160 degrees vertically, horizontally, and horizontally has been developed and put into practical use.

[0005]

On the other hand, in view of the usage of the liquid crystal display element, a wide viewing angle characteristic is required when viewing the display by a large number of people or when viewing the display from various angles. In the case of personal recording using a notebook computer or a portable terminal, on the contrary, a narrow viewing angle characteristic that cannot be seen by others is required.

In response to this demand, a method of using spectacles with a polarizing plate instead of the polarizing plate on the viewer side of the liquid crystal display element,
As required, a method using a viewing angle control plate whose transmission / scattering characteristics change depending on the viewing angle has been proposed. However, there is a problem that mounting and demounting to and from the liquid crystal display device is troublesome.

In view of the above, the present invention mainly aims to provide a liquid crystal display device which can easily and arbitrarily and easily switch between a wide viewing angle characteristic and a narrow viewing angle characteristic depending on a use mode. Aim.

[0008]

In order to achieve the above object, a first liquid crystal display device of the present invention has a display liquid crystal element and a phase difference control liquid crystal element, and comprises a phase difference control liquid crystal element. However, a cholesteric liquid crystal or a chiral nematic liquid crystal having a planar orientation is sandwiched between substrates having electrodes on the inner surface.

A second liquid crystal display device of the present invention has a display liquid crystal element and a phase difference control liquid crystal element, and the phase difference control liquid crystal element is isotropic when the liquid crystal display device is used, and a voltage is applied. , A nematic liquid crystal that is vertically aligned is sandwiched between substrates having electrodes on the inner surface.

Further, a third liquid crystal display device of the present invention has a display liquid crystal element and a phase difference control liquid crystal element, wherein the phase difference control liquid crystal element has a nematic liquid crystal having random orientation on an inner surface. Is sandwiched between substrates having the same.

According to the above arrangement, the viewing angle characteristics of the entire liquid crystal display device can be easily changed by controlling the voltage applied to the phase difference controlling liquid crystal element.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a liquid crystal display according to an embodiment of the present invention will be described in detail with reference to the drawings.

(Embodiment 1) FIG. 1 is a sectional view showing a configuration concept of a liquid crystal display device according to Embodiment 1 of the present invention. In FIG. 1, the liquid crystal display device includes polarizing plates 1 and 20, and a display liquid crystal element 10 and a compensation liquid crystal element 19 disposed therebetween.

The display liquid crystal element 10 was manufactured as follows. First, an alignment film paint SE- manufactured by Nissan Chemical Industries, Ltd. is placed on two glass substrates 2 and 9 having transparent electrodes 3 and 8.
1211 is applied by spin coating, and
Cure for 1 hour at ° C. Thereafter, rubbing treatment is performed in the direction shown in FIG. 2 using a rubbing cloth made of rayon, and spacers 5 made by Sekisui Fine Chemical Co., Ltd. and Stract Bond 352A (trade name of seal resin made by Mitsui Toatsu Chemicals, Inc.) are used. Then, the substrates were stuck together so that the distance between the substrates became 3 μm, thereby producing a liquid crystal cell for display. Next, a liquid crystal MJ951152 manufactured by Merck (NI point = 91 ° C., Δn = 0.0082)
7) was injected into the above-mentioned liquid crystal cell by a vacuum injection method to obtain a display liquid crystal element 10.

The phase difference controlling liquid crystal element 19 was manufactured as follows. First, 2 having transparent electrodes 12 and 17
An alignment film paint SE-7492 manufactured by Nissan Chemical Industries is applied on the glass substrates 11 and 18 by spin coating, and cured at 180 ° C. for 1 hour in a thermostat. Then, rubbing treatment is performed in the direction shown in FIG. 2 using a rubbing cloth made of rayon, and spacers 14 manufactured by Sekisui Fine Chemical Co., Ltd. and Stract Bond 352A (trade name of seal resin manufactured by Mitsui Toatsu Chemicals, Inc.) are used. Then, the substrates were stuck together so that the distance between the substrates became 8 μm, thereby producing a liquid crystal cell for controlling a phase difference. Next, as a liquid crystal to be planar-aligned, cholesteryl nonanoate as a chiral material is added, and a liquid crystal ZLI-2411 manufactured by Merck Ltd. (NI point = 65 ° C., Δn = 0. 14
0) was injected into the above-mentioned liquid crystal cell by a vacuum injection method to obtain a liquid crystal cell 19 for controlling a phase difference.

After that, as shown in FIG. 2, the polarizers 1 and 20 are oriented at a 45 ° angle between the rubbing direction of the display liquid crystal element light source side substrate and the polarization axis direction of the polarizer 1, and the polarization of the two polarizers. The liquid crystal display device A was manufactured by bonding the liquid crystal elements 10 and 19 such that the axial directions were orthogonal to each other.

Next, the voltage-transmittance characteristic of the liquid crystal display device A of the present invention was measured at 25 ° C. while applying a 30 Hz rectangular wave according to a conventional method. The result is shown in FIG. Approximately the same voltage-transmittance characteristics were obtained both when a voltage of 10 V was applied to the phase difference controlling liquid crystal element and when no voltage was applied.

When the ratio between the transmittance when 8 V is applied to the display liquid crystal element and the transmittance when no voltage is applied is defined as a contrast ratio, and a voltage of 10 V is applied to the phase difference control liquid crystal element. And the case where no voltage was applied, the dependence of the contrast ratio on the viewing angle was measured. FIG. 4 shows the results.

In the figure, the solid line is an isocontrast curve when 10 V is applied to the phase control element, and the dashed line is an isocontrast curve when no voltage is applied to the phase difference control element. Here, the region surrounded by the curve is a region where the contrast ratio is 10: 1 or more, and represents a region without gradation inversion.

As is apparent from FIG. 4, the liquid crystal display device of the present embodiment changes the viewing angle characteristic of the liquid crystal display device from “wide viewing angle ← → narrow viewing angle” depending on the presence or absence of a voltage applied to the phase difference controlling liquid crystal element. Switching is possible, and the viewing angle characteristic can be selected according to the usage pattern.

The liquid crystal molecules in the liquid crystal element for phase difference control according to the present embodiment have a planar arrangement in which the helical axis is oriented perpendicular to the substrate surface when no voltage is applied. Since the refractive index in the direction shows the same function as that of a negative compensator having the relationship of nx = ny> nz, the phase difference of the liquid crystal element for display in which the liquid crystal molecules are oriented almost perpendicular to the substrate surface in the element. The viewing angle dependency can be compensated, the viewing angle dependency of the phase difference of the present liquid crystal display device can be greatly reduced, and a wide viewing angle can be achieved.

When a voltage is applied to the phase difference controlling liquid crystal element, the liquid crystal molecules are arranged almost perpendicular to the substrate surface, so that the characteristics of the display liquid crystal element alone are observed in front of the apparatus. When the viewing angle is inclined from the front, the phase difference of the liquid crystal element for controlling the phase difference is added to the phase difference of the liquid crystal element for display, and the viewing angle characteristic of the liquid crystal display device is greatly reduced.

In this embodiment, a chiral nematic liquid crystal is used to achieve cholesteric planar alignment. However, other cholesteric liquid crystals may be used as long as they are aligned almost perpendicular to the substrate surface by applying a voltage. Needless to say.

The display liquid crystal element has a display mode in which black display is performed in a state where liquid crystal molecules at the center of the element are arranged almost vertically, for example, a normally white twisted nematic mode, a vertical alignment type electric field induced birefringence mode, or Particularly qualified for optically compensated bend mode.

Further, it is needless to say that the same effect can be obtained when an alignment division type liquid crystal display element in which each pixel in the element is divided into a plurality of areas or an innumerable area is used as a display element. .

Embodiment 2 Hereinafter, a liquid crystal display device according to Embodiment 2 of the present invention will be described. This embodiment is a liquid crystal display device having a configuration similar to that of FIG. 1 presented in Embodiment 1 described above, and is basically different from Embodiment 1 in the liquid crystal of the phase difference control display element. . Then, the liquid crystal display device B according to the present embodiment was manufactured as follows.

The display liquid crystal element 10 was manufactured as follows. First, an alignment film paint SE-7492 manufactured by Nissan Chemical Industries is applied on two glass substrates 2 and 9 having transparent electrodes 3 and 8 by a spin coating method, and cured at 180 ° C. for 1 hour in a thermostat. Thereafter, rubbing treatment is performed in the direction shown in FIG. 5 using a rubbing cloth made of rayon, and spacers 5 made by Sekisui Fine Chemical Co., Ltd.
Using 2A (trade name of seal resin manufactured by Mitsui Toatsu Chemicals, Inc.), the substrates were bonded together so that the distance between the substrates was 5 μm, thereby producing a liquid crystal cell for display. Next, a liquid crystal ZLI-4792 (NI, manufactured by Merck & Co., Inc.) is used as a liquid crystal which shows an isotropic phase within the operating temperature range of the liquid crystal display device and in which molecules are arranged on the substrate by applying voltage.
(Point = 91 ° C., Δn = 0.094) was injected into the above-mentioned liquid crystal cell by a vacuum injection method to obtain a display liquid crystal element 10.

The phase difference controlling liquid crystal element 19 was manufactured as follows. First, 2 having transparent electrodes 12 and 17
An alignment film paint SE-7492 manufactured by Nissan Chemical Industries, Ltd. is applied onto the glass substrates 11 and 18 by spin coating, and cured at 180 ° C. for 1 hour in a thermostat. Thereafter, a rubbing treatment is performed using a rubbing cloth made of rayon in the direction shown in FIG. Then, the substrates were stuck together so that the distance between the substrates became 5 μm, thereby producing a liquid crystal cell for controlling a phase difference. Next, 4-pentyl-4′-cyanobiphenyl (NI point =
35.5 ° C., Δn = 0.184) was injected into the above-mentioned liquid crystal cell by a vacuum injection method to obtain a liquid crystal cell 19 for controlling a phase difference.

Then, as shown in FIG. 5, the polarizers 1 and 20 are aligned so that the rubbing direction of the display liquid crystal element light source side substrate and the polarization axis direction of the polarizer 1 coincide with each other. Were bonded to the liquid crystal elements 10 and 19 so that the liquid crystal display device B was orthogonally arranged.

Next, the voltage-transmittance characteristic of the liquid crystal display device B of the present invention was measured at 38 ° C. while applying a 30 Hz rectangular wave according to a conventional method. FIG. 6 shows the result. Approximately the same voltage-transmittance characteristics were obtained when a voltage of 5 V was applied to the phase difference controlling liquid crystal element and when no voltage was applied.

Now, the ratio between the transmittance when 5 V is applied to the display liquid crystal element and the transmittance when no voltage is applied is defined as the contrast ratio, and when a voltage of 5 V is applied to the phase difference control liquid crystal element. And the case where no voltage was applied, the dependence of the contrast ratio on the viewing angle was measured. FIG. 7 shows the result. In the figure, the solid line is an isocontrast curve when 5 V is applied to the phase control element, and the broken line is an isocontrast curve when no voltage is applied to the phase difference control element. Here, the region surrounded by the curve has a contrast ratio of 1
It is a region of 0: 1 or more, and represents a region without gradation inversion.

As is apparent from FIG. 7, the liquid crystal display device of the present embodiment changes the viewing angle characteristic of the liquid crystal display device from “wide viewing angle ← → narrow viewing angle” depending on the presence or absence of a voltage applied to the phase difference controlling liquid crystal element. Switching is possible, and the viewing angle characteristic can be selected according to the usage pattern.

The liquid crystal molecules in the liquid crystal element for controlling a phase difference according to the present embodiment have an NI point of 35.5 ° C. and have an isotropic phase around 40 ° C., which is the liquid crystal display element temperature during normal use. When no voltage is applied to the phase difference controlling liquid crystal element, the phase difference controlling layer has no optical function, but the orientation order as a minute cluster remains, so that the liquid crystal molecules are not applied by the voltage application. Are arranged perpendicular to the surface of the substrate and exhibit an optical function. Therefore, when the liquid crystal display device is observed from an oblique direction, not only a sufficient contrast cannot be obtained due to the phase difference of the liquid crystal element for controlling the phase difference, but also the gray scale inversion and the hue change in the halftone are remarkable, and the display is not displayed. It becomes extremely difficult to recognize.

The degree of narrowing the viewing angle can be arbitrarily changed by adjusting the refractive index anisotropy Δn of the liquid crystal material, the thickness d of the retardation control layer, and the NI point.

In this embodiment, 4-pentyl-4'-cyanobiphenyl is used as the liquid crystal material for controlling the phase difference. However, the present invention is not limited to this. And other materials are also suitable as long as the liquid crystal molecules are aligned perpendicular to the substrate surface by applying a voltage.

The same effect can be obtained by further adding a chiral material to the liquid crystal material for controlling a phase difference used in the present embodiment.

Further, in the present embodiment, a twisted nematic (TN type) liquid crystal display element is used as a display element.
A liquid crystal element including isotropic liquid crystal is used as a phase difference control element for controlling a viewing angle, but another compensating layer such as a phase plate is added for the purpose of further improving the viewing angle characteristics at a wide viewing angle. Needless to say, the same effect can be obtained.

In this embodiment, a homogeneously aligned liquid crystal element is used as a liquid crystal element for controlling a phase difference. However, the same effect was confirmed in a liquid crystal element having a twist alignment and a liquid crystal element exhibiting a random alignment.

Embodiment 3 Hereinafter, a liquid crystal display device according to Embodiment 3 of the present invention will be described. This embodiment is a liquid crystal display device having a configuration similar to that of FIG. 1 presented in Embodiment 1 described above, and is basically different from Embodiment 1 in the liquid crystal of the phase difference control display element. . Then, the liquid crystal display device C according to the present embodiment was manufactured as follows.

The display liquid crystal element 10 used was the display liquid crystal element manufactured in the first embodiment. Further, the phase difference controlling liquid crystal element 19 was manufactured as follows.

First, an alignment film paint S manufactured by Nissan Chemical Industries is placed on two glass substrates 11 and 18 having transparent electrodes 12 and 17.
E-7492 was applied by spin coating and placed in a thermostat.
Cure for 1 hour at 80 ° C. Then, Sekisui Fine Chemical Co., Ltd. spacer 14 and Structbond 3
Using 52A (trade name of sealing resin manufactured by Mitsui Toatsu Chemicals, Inc.), the substrates were bonded together so that the distance between the substrates was 5 μm, thereby producing a liquid crystal cell for phase difference control. Next, a liquid crystal material ZLI-2411 manufactured by Merck (NI point = 65 ° C., Δn = 0.14)
0) was injected into the above liquid crystal cell in an isotropic phase state by a vacuum injection method to obtain a liquid crystal cell 19 for controlling a phase difference.

Then, as shown in FIG. 8, the polarizers 1 and 20 are oriented at a 45 degree angle between the rubbing direction of the display liquid crystal element light source side substrate and the polarization axis direction of the polarizer 1 and the polarization of the two polarizers. The liquid crystal display device C was manufactured by bonding the liquid crystal elements 10 and 19 so that the axial directions were orthogonal to each other.

Next, the voltage-transmittance characteristic of the liquid crystal display device C of the present invention was measured at 25 ° C. while applying a 30 Hz rectangular wave according to a conventional method. The results were the same as those in FIG. 3, and almost the same voltage-transmittance characteristics were obtained when a voltage of 10 V was applied to the phase difference controlling liquid crystal element and when no voltage was applied.

Now, the ratio of the transmittance when 5 V is applied to the display liquid crystal element to the transmittance when no voltage is applied is defined as a contrast ratio, and when a voltage of 10 V is applied to the phase difference control liquid crystal element. And the case where no voltage was applied, the dependence of the contrast ratio on the viewing angle was measured. FIG. 9 shows the result.
In the figure, the solid line is an isocontrast curve when 10 V is applied to the phase control element, and the broken line is an isocontrast curve when no voltage is applied to the phase difference control element. Here, the region surrounded by the curve is a region where the contrast ratio is 10: 1 or more, and represents a region without gradation inversion.

As is clear from FIG. 9, the liquid crystal display device of the present embodiment changes the viewing angle characteristic of the liquid crystal display device from “wide viewing angle ← → narrow viewing angle” depending on the presence or absence of a voltage applied to the phase difference controlling liquid crystal element. It is possible to switch. In addition, it was confirmed that the viewing angle characteristics of the liquid crystal display device can be controlled by controlling the voltage applied to the phase difference controlling liquid crystal element.

In the liquid crystal element substrate for phase difference control according to the present embodiment, no alignment treatment is performed, so that the liquid crystal molecules in the element are almost randomly oriented, and the phase difference control layer has no optical function. Although not provided, the liquid crystal molecules are arranged perpendicular to the substrate surface by applying a voltage, and exhibit an optical function.

As the liquid crystal material for controlling the phase difference, a material in which liquid crystal molecules are arranged perpendicular to the substrate surface by applying a voltage is suitable, and is not limited to the liquid crystal material used in the present embodiment.

The same effect can be obtained by adding a chiral material to the liquid crystal material for controlling phase difference used in the present embodiment.

The liquid crystal display device of the present invention has been described above. In the above embodiment, an embodiment using a transmissive display device has been described. However, the present invention can be applied to a reflective display device. Needless to say, the present invention can be applied to an active matrix type liquid crystal display device such as a TFT or MIM.

[0050]

As described above, according to the present invention, it is possible to arbitrarily switch between the wide viewing angle characteristic and the narrow viewing angle characteristic depending on the use mode of the liquid crystal display device. Both confidentiality can be achieved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically showing a liquid crystal display device according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating an arrangement direction of each optical element of the liquid crystal display device according to the first embodiment of the present invention.

FIG. 3 is a diagram showing a voltage-transmittance characteristic of the liquid crystal display device according to the first embodiment of the present invention.

FIG. 4 is a diagram showing viewing angle characteristics of the liquid crystal display device according to Embodiment 1 of the present invention.

FIG. 5 is a diagram showing an arrangement direction of each optical element of the liquid crystal display device according to the second embodiment of the present invention.

FIG. 6 is a diagram showing voltage-transmittance characteristics of a liquid crystal display device according to a second embodiment of the present invention.

FIG. 7 is a view showing viewing angle characteristics of a liquid crystal display device according to Embodiment 2 of the present invention.

FIG. 8 is a diagram showing an arrangement direction of each optical element of a liquid crystal display device according to a third embodiment of the present invention.

FIG. 9 is a diagram showing viewing angle characteristics of a liquid crystal display device according to Embodiment 3 of the present invention.

[Explanation of symbols]

 1,20 polarizing plate 2,9,11,18 glass substrate 3,8,12,17 transparent electrode 4,7,13,16 alignment film 5,14 spacer 6,15 liquid crystal layer 10 display liquid crystal element 19 phase difference control Liquid crystal element

Claims (8)

[Claims] 1. A liquid crystal display device having a display liquid crystal element and a phase difference control liquid crystal element, wherein the phase difference control liquid crystal element has a planar cholesteric liquid crystal or a chiral nematic liquid crystal on its inner surface. A liquid crystal display device sandwiched between substrates having: 2. A liquid crystal display device having a display liquid crystal element and a phase difference control liquid crystal element, wherein the phase difference control liquid crystal element is isotropic when the liquid crystal display device is used, and is vertically aligned by applying a voltage. A liquid crystal display device, wherein a nematic liquid crystal is sandwiched between substrates having electrodes on an inner surface thereof. 3. A liquid crystal display device having a display liquid crystal element and a phase difference control liquid crystal element, wherein the phase difference control liquid crystal element is formed of a nematic liquid crystal having a random alignment between substrates having electrodes on an inner surface thereof. A liquid crystal display device characterized by being sandwiched between them. 4. The liquid crystal display device according to claim 1, wherein a viewing angle characteristic of the liquid crystal display device is controlled by controlling a voltage applied to the phase difference controlling liquid crystal element. 5. The liquid crystal display device according to claim 1, wherein the liquid crystal in the display liquid crystal element is substantially vertically aligned at least at one of the substrate interfaces without applying a voltage. . 6. The liquid crystal display device according to claim 1, wherein the liquid crystal in the display liquid crystal element has a liquid crystal substantially vertically aligned at a central portion of the element when a voltage is applied. 7. The liquid crystal display device according to claim 1, wherein the display liquid crystal element is a twisted nematic liquid crystal element. 8. The liquid crystal display device according to claim 1, wherein the liquid crystal display device has a compensation layer.