JP2000147477A - Liquid crystal display device as well as its production and drive method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display device capable of enhancing the light utilization rate within the same space and a drive method therefor. SOLUTION: This device is formed with a plurality of periodic structures where refractive indices are modulated within the same space. The respective periodic structures are the multilayered structures alternately laminated with the layers consisting of liquid crystal materials capable of controlling alignment directions by electric fields and the layers consisting of photosetting materials not capable of controlling the alignment directions by electric fields. The respective periodic structures include electrode pairs for selective reflecting and independent driving of different wavelength bands. This process for production has a stage for holding the mixture composed of the liquid crystal material and the photosetting material having optical anisotropy between substrates and aligning the mixture to the plural directions and a stage for producing the multiple and multilayered structures alternately laminated with the layers in which the photosetting materials are polymerized and the layers in which the photosetting materials are not polymerized by irradiating the substrates holding the mixture with plural beams of interference light. This drive method is a drive production method for the liquid crystal display device having the multilayered structures and independently drives the respective layers by impressing the electric field which is substantially unidirectional by changing the direction with lapse of time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a liquid crystal display device and a method of manufacturing and driving the same.

[0002]

2. Description of the Related Art Notebook computers and PDAs (Personal Dig)
The demand for portable information devices such as ital assistants) is increasing, and the demand for a display capable of color display with high display quality as well as low power consumption, thinness and light weight is increasing. To achieve this, a reflective color liquid crystal display device has been actively researched and developed. Among them, a Bragg reflection volume hologram optical element that does not use a polarizing element or a color filter has attracted attention. This Bragg reflection type element can reflect almost 100% of light having a wavelength that satisfies the Bragg condition in principle, so that a display with high brightness and high color purity is expected.

As the above-mentioned volume hologram optical element,
For example, an optical element described in JP-A-6-294952 can be used. FIG. 7 is a schematic diagram of a display element described in Japanese Patent Application Laid-Open No. 6-294952, and the operation principle of this optical element will be described with reference to FIG. When the incident light 108 is incident when no voltage is applied, Bragg reflection occurs due to the refractive index difference and the periodic interval between the liquid crystal droplet 105 and the polymer material 106, and reflects light 109 in a specific wavelength band. The light having the wavelength is transmitted 110. This state is used as the reflection state of the display element. Next, when a voltage is applied between the transparent electrode 103 and the transparent electrode 104, the liquid crystal droplet 10
5, the liquid crystal droplet 105 and the polymer material 10 change.
6, the Bragg reflection intensity decreases as the difference in refractive index decreases, and when the difference in refractive index completely disappears, all the incident light 108 is transmitted. This state is used as the transmission state of the display element.

However, in the above-mentioned optical element, the liquid crystal exhibits a random orientation in the element when no voltage is applied, so that the refractive index of the liquid crystal layer becomes smaller than the refractive index difference calculated from the anisotropy of the liquid crystal. However, there is a problem that the reflectance determined by the refractive index difference from the polymer material cannot be used to the maximum. As a solution to this, there is an optical element described in JP-A-10-123561.

As shown in FIGS. 8 and 9, the optical element disclosed in Japanese Patent Application Laid-Open No. H10-123561 includes an optically anisotropic material (21) that can be controlled by an electric field and an optically anisotropic material (22) that does not depend on voltage. ) Is a multilayer structure (20) oriented in a certain direction and alternately stacked. In this structure, the optically anisotropic material (23) controlled by an electric field by applying a voltage is reoriented in the direction of the electric field, and the optically anisotropic material (2) independent of the electric field is applied.
When the reflection state in which the orientation direction is orthogonal to that of 4) is formed, the difference in the refractive index of the optical anisotropy can be used to the maximum, so that the reflection intensity also becomes maximum, and the above problem can be solved.

[0006]

However, in the device configurations described in JP-A-6-294952 and JP-A-10-123561, monochromatic Bragg reflected light is utilized by utilizing certain incident light in the same space. However, there is a problem that the light use efficiency in the same space is low.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and has as its object to provide a plurality of periodic structures capable of selectively reflecting light of different wavelengths in the same space, and these periodic structures are independent. Equipped with a structure that can be driven
It is an object of the present invention to provide a liquid crystal display device capable of improving light use efficiency in the same space. Another object of the present invention is to provide a manufacturing method and a driving method of a liquid crystal display device having the above structure.

[0008]

According to the present invention, there is provided a liquid crystal display device having the following features (1) to (5):
(6) A method for manufacturing a liquid crystal display device shown in (11) and a method for driving a liquid crystal display device shown in (12) to (15) are provided.

(1) A plurality of periodic structures whose refractive index is modulated are formed in the same space. Each periodic structure has a layer made of a liquid crystal material whose orientation can be controlled by an electric field, and a light whose orientation can not be controlled by an electric field. A liquid crystal display device having a multilayer structure in which layers made of a curable material are alternately stacked, and having an electrode pair for selectively reflecting different wavelength bands in each periodic structure and independently driving the same.

(2) The liquid crystal display device according to (1), wherein a liquid crystal having a negative dielectric anisotropy is used as a liquid crystal material, and a liquid crystal monomer which is an optically anisotropic material is used as a photocurable material.

(3) A dual frequency liquid crystal whose dielectric anisotropy becomes positive or negative depending on the frequency of an applied voltage as a liquid crystal material, and a liquid crystal monomer which is an optically anisotropic material as a photocurable material. Liquid crystal display.

(4) The liquid crystal display device of (1) to (3), wherein two periodic structures are formed in the same space, and the orientation directions between the periodic structures are orthogonal.

(5) The liquid crystal display device according to any one of (1) to (3), wherein three periodic structures are formed in the same space, and the alignment directions between the periodic structures are different by 60 °.

(6) The method for manufacturing a liquid crystal display device according to any one of the above (1) to (5), wherein a mixture of a liquid crystal material and a photocurable material having optical anisotropy is sandwiched between substrates and oriented in a plurality of directions. And a step of irradiating the sandwiched substrate with a plurality of interference lights to produce a multilayer structure in which layers in which the photocurable material is polymerized and layers in which the photocurable material is not polymerized are alternately stacked. Device manufacturing method.

(7) Of the four light beams, two light beams are P-polarized with respect to the incident surface, and the two light beams interfere with each other, and the remaining two light beams interfere with each other.
(6) The method for manufacturing a liquid crystal display device according to (6), wherein the light beam interferes with S-polarized light.

(8) The method of manufacturing a liquid crystal display device according to (6) or (7), wherein the incident angles of the polarized lights are different.

(9) The liquid crystal display of (6), wherein two lasers oscillating different single wavelengths are used, each laser beam is split into two light beams, and the two split light beams interfere with each other to cure the photocurable material. Device manufacturing method.

(10) The method for manufacturing a liquid crystal display device according to (9), wherein the polarization of two light beams branched from one laser beam with respect to the incident surface is P-polarization, and the polarization of the remaining two light beams is S-polarization.

(11) 2 branched from one laser beam
The method of manufacturing a liquid crystal display device according to (9) or (10), wherein the crossing angle of the light flux is an angle that does not become the same as the interval between interference fringes produced by another laser.

(12) The method for driving a liquid crystal display device according to any one of (1) to (5), wherein different voltages are applied to the plurality of electrode pairs to generate an electric field substantially in one direction. How to drive the device.

(13) In the method of driving a liquid crystal display device according to any one of the above (1) to (5), different voltages are applied to a plurality of electrode pairs for a certain period of time to generate a substantially unidirectional electric field. After that, the operation of changing the value of the applied voltage and generating an electric field in a substantially one direction in a direction different from the electric field for a certain period of time is repeated, and an electric field in a plurality of directions is generated substantially as an average of the voltage application time. Of driving a liquid crystal display device to be driven.

(14) The number of electrode pairs is four (12)
Is a driving method of the liquid crystal display device according to (13).

(15) The method for driving a liquid crystal display device according to (13) or (14), wherein the plurality of qualitative directions are two directions orthogonal to each other.

The outline of a typical invention disclosed in the present invention will be briefly described below. In the liquid crystal display device of the present invention, a plurality of periodic structures with variable refractive index modulation are formed in the same space, and each periodic structure has a layer made of a liquid crystal material whose orientation can be controlled by an electric field, and It has a multilayer structure in which layers of photocurable materials having optical anisotropy that cannot be controlled are alternately stacked, and can be driven independently, and each periodic structure selectively reflects different wavelength bands. And a plurality of electrode pairs for driving independently of each other.

It is preferable that the electrode pairs use a plurality of pairs of electrodes in order to obtain a uniform electric field in one direction in the display area. In this case, as shown in FIG.
Although a pair (37, 38) may be used, the number of electrode pairs is preferably large. However, if the number is too large, the production of the display device and the like become complicated, so it is desirable to use, for example, four pairs of electrodes (39) as shown in FIG. Although the purpose is quite different, it is possible to rotate the liquid crystal in the portion surrounded by the electrodes by generating an electric field in substantially one direction by such electrodes, and to change the direction with time, O pl
us E, vol. 20, No. 10, P. 1145 (1988). That is, when different voltages are regularly applied to the four pairs of electrodes as shown in FIG. 1C, an electric field in substantially one direction can be generated by superposition of the electric fields. At this time, the cross section of the electrode may be a complete wall as shown in FIG. 1 (d) to produce a substantially uniform electrode in a direction parallel to the substrate, or as shown in FIG. 1 (e). The electrodes may be formed only on one of the substrates.
Alternatively, electrodes may be formed on the upper and lower substrates as shown in FIG. 1 (f) so that an electric field inclined with respect to the substrate is generated.

Each periodic structure in the liquid crystal display device of the present invention is composed of a layer of a liquid crystal material whose orientation can be controlled by an electric field and a layer of a photocurable material having optical anisotropy whose orientation can not be controlled by an electric field. Bragg reflection is caused by the refractive index difference, and the refractive index difference can be changed independently by the electrode pair provided for each periodic structure, and different wavelength bands can be reflected by the refractive index period of each periodic structure. it can. And since each periodic structure uses different incident light, the light use efficiency in the same space can be improved.

The method for manufacturing a liquid crystal display device according to the present invention comprises the steps of sandwiching a mixture of a liquid crystal material and a photocurable material having optical anisotropy between substrates and aligning the mixture in a plurality of directions;
Irradiating the sandwiched substrate with a plurality of interference lights to produce a multilayer structure in which a layer in which the photocurable material is periodically polymerized and a layer in which the photocurable material is not polymerized are alternately stacked. .

According to the above method, a mixture of a liquid crystal material and a photocurable material having optical anisotropy is sandwiched between substrates.
Orienting the mixture in at least multiple directions,
By irradiating the sandwiched substrate with a plurality of interference lights and alternately or simultaneously with the step of polymerizing the photocurable material, the liquid crystal material layer whose alignment direction can be controlled by an electric field and the liquid crystal material layer are aligned independently of the electric field. A photo-curable material layer is alternately laminated, a liquid crystal layer and a photo-curable material layer have almost the same alignment direction, and a multi-layered structure having a plurality of alignment directions can be manufactured.

Here, as the liquid crystal material whose orientation direction can be controlled by an electric field, a liquid crystal having a negative dielectric anisotropy or a dual-frequency liquid crystal having a positive or negative dielectric anisotropy depending on the frequency of an applied voltage is used. A liquid crystalline monomer having photosensitivity may be used as the optically anisotropic material oriented without depending on the electric field.

In the step of orienting the mixture in a plurality of directions and the step of polymerizing the photocurable material, an electric field is applied to each electrode pair to orient the mixture in the direction of the electric field. The step of polymerizing the photocurable material may be repeated a plurality of times while sequentially changing the orientation direction of the mixture using an electric field. In addition, a step of performing rubbing treatment a plurality of times, orienting the mixture in a plurality of directions, and irradiating the mixture with a plurality of interference lights having different polarization directions sequentially or simultaneously to polymerize the photocurable material may be performed. . As a light source for polymerizing the photocurable material, a laser that oscillates a single wavelength may be branched into a plurality of pieces to create interference light, or an interference light may be created using a plurality of lasers that oscillate different wavelengths. Good.

Next, the operation principle of the liquid crystal display device of the present invention will be described. As shown in FIG. 1, the extraordinary optical axes of the liquid crystal material 31 and the photocurable material 32 having optical anisotropy in the first cycle are in the same direction, and the liquid crystal material 33 in the second cycle is The extraordinary optical axis of the photocurable material having anisotropy is oriented in a direction orthogonal to the extraordinary optical axis of the first periodic structure. In order to drive each periodic structure, FIG.
In the state where no voltage is applied, the refractive index difference between the liquid crystal material and the photocurable material is the same, so that Bragg reflection does not occur, and the incident light is It becomes a transmission state in which all light is transmitted.

Here, when a voltage is applied to the four pairs of electrodes at a ratio as shown in FIG. 1C for a certain period of time, a substantially unidirectional electric field is generated in the major axis direction of the liquid crystal 31. When a liquid crystal having a negative dielectric anisotropy is used, the liquid crystal rotates so that its major axis is directed perpendicular to the electric field. At this time, in order to prevent the rotation parallel to the substrate, the second voltage is changed to the voltage of FIG. 1C for another predetermined time so that an electric field substantially unidirectional in the major axis direction of the liquid crystal 33 is generated. What is necessary is just to apply in the direction rotated 90 degrees by the ratio. Further, if the different voltage in the 90 ° direction is equal to or lower than the voltage of the Freedericksz transition of the liquid crystal 31, the liquid crystal 33
Does not rotate.

If the above voltages are alternately applied in a cycle within the response time of the liquid crystal, only the liquid crystal 31 can be rotated in the direction perpendicular to the substrate. As a result, only the liquid crystal in the first cycle responds. A difference in the refractive index occurs, satisfying the Bragg condition, and only reflected light corresponding to this period is generated.

This is because a lateral electric field as shown in FIG. 2 is applied to one electrode pair, and only the liquid crystal material oriented in the electric field direction is re-oriented in the electric field direction. Since a refractive index difference is generated between the first and second states, Bragg reflection occurs, which is equivalent to the formation of the first reflection state. At this time, since the alignment direction of the liquid crystal material in another cycle is orthogonal to the direction of the electric field, the liquid crystal material does not reorient in the direction of the electric field, and Bragg reflection from this periodic structure does not occur. When it is desired to rotate the liquid crystal 33, the second voltage may be set to a voltage higher than the Freedericksz transition, and the rotation of the liquid crystal 31 in a plane perpendicular to the substrate is not affected by this electric field. At this time, the second reflection state can be formed. The wavelength reflected here is different from the wavelength in the first reflection state because the periodic interval of the periodic structure is different. Since a plurality of periodic structures formed in the same space can be driven independently and different wavelengths can be selectively reflected, the light use efficiency in the same space can be improved.

[0035]

Embodiments of the present invention will be described below with reference to the drawings. 1A and 1B are diagrams illustrating a configuration of a liquid crystal display device according to a first embodiment of the present invention, in which FIG. 1A is a cross-sectional view schematically illustrating the configuration of the device, FIG.
(C) is a plan view showing an example of a desirable electrode structure,
(D), (e), and (f) are three types of cross-sectional views of a desirable electrode structure. In FIG. 1, 31 is a liquid crystal material in the first periodic structure, 32 is a photocurable material in the first periodic structure, 33 is a liquid crystal material in the second periodic structure, 34
Is a photocurable material in the second periodic structure; 35 and 36 are substrates sandwiching a mixture of a liquid crystal material and a photocurable material;
7 is an electrode pair for applying an electric field to the first periodic structure,
Reference numeral 8 denotes an electrode pair for applying an electric field to the second periodic structure. Reference numeral 39 denotes an electrode pair capable of generating an electric field substantially in one direction.

The electrode pair 37 of the display device according to the present embodiment.
, 38 and 39 can apply an electric field in parallel to the substrates 35 and 36, and the direction of the electric field between the electrode pair 37 and the electrode pair 38 is orthogonal to the vicinity of the center of the pixel. The electrode pair 37 is provided for driving a liquid crystal material having a first periodic structure, and the electrode pair 38 is provided for driving a liquid crystal material having a second periodic structure.

A polyimide alignment film is provided on each of the substrates 35 and 36 so that the alignment direction of the liquid crystal and the liquid crystalline monomer is perpendicular to the direction parallel to the electric field direction by the electrode pair 37. Rubbing treatment,
They are bonded at an interval of about 10 μm so as to be anti-parallel. A mixture of a liquid crystal having a negative dielectric anisotropy and a photocurable liquid crystalline monomer polymerized by light irradiation and having the same orientation as the liquid crystal is injected therein.

The injected liquid crystal and liquid crystalline monomer are oriented in two directions, that is, the direction of the electric field by the electrode pair 37 and the direction perpendicular thereto, due to the effect of the rubbing treatment. When the display device is irradiated with interference light described later, the liquid crystal monomer is polymerized in a state where the liquid crystal monomer is oriented at the antinode of the standing wave due to the interference, and the liquid crystal monomer polymerized layer and the liquid crystal monomer are not polymerized. A first periodic structure in which layers (ie, liquid crystal material layers) are alternately stacked is formed. At this time, all liquid crystal monomers are not polymerized. That is, the irradiation amount is at most １ ／ or less of the irradiation amount necessary for completing the polymerization.

After the first periodic structure is formed by the above-described operation, the interference light is applied to the display device in the same manner as described above by changing the periodic interval of the standing wave according to the incident angle of the laser or using a laser having a different wavelength. Is irradiated, the liquid crystalline monomer is polymerized in the aligned state, and a second periodic structure is formed. As a result of these operations, two periodic structures can be produced in the same space, and the orientation directions of the two periodic structures are orthogonal.

In the display device of the first embodiment, when no voltage is applied, there is no difference in the refractive index because the liquid crystal and the liquid crystalline monomer in each periodic structure are oriented.
Further, since there is no periodicity between the first and second periodic structures, reflected light due to Bragg reflection is not observed, and the structure is in a transparent state. However, when a voltage is applied to the electrode pair 37, the liquid crystal material 31 having the first periodic structure is reoriented in the direction of the electric field, and an effect of observing blue reflected light due to Bragg reflection occurs. At this time, the liquid crystal material 33 having the second periodic structure does not reorient due to the electric field since the direction of the electric field is orthogonal to the orientation direction, and does not cause Bragg reflection. When a voltage is applied to the electrode pair 38, the liquid crystal material 3 having the second periodic structure
3 is re-oriented in the direction of the electric field, and a refractive index is generated between the liquid crystal material and the liquid crystalline monomer having the second periodic structure, so that an effect of observing green reflected light due to Bragg reflection occurs.

The liquid crystal display device according to the second embodiment of the present invention comprises the two substrates 35 and 3 shown in the first embodiment.
6, a mixture of a liquid crystal and a photocurable liquid crystalline monomer is sandwiched, and an electrode pair 39 is provided. The difference from the first embodiment is that the electrode pair 39 can apply an electric field in substantially one direction over a wide range in a pixel for an arbitrary time. Another feature is that orthogonal electric fields are applied to the liquid crystal in a time-division manner.

As in the first embodiment, both substrates 35, 3
6 are provided with polyimide alignment films, respectively.
Rubbing is performed so that the orientation direction of the liquid crystal and the liquid crystalline monomer is orthogonal to the direction parallel to the direction of the arrow 40, and the substrates are bonded at an interval of about 10 μm so as to be antiparallel. A mixture of a liquid crystal having a negative dielectric anisotropy and a photocurable liquid crystalline monomer polymerized by light irradiation and having the same orientation as the liquid crystal is injected therein.

The injected liquid crystal and liquid crystalline monomer are oriented in two directions, the direction of the arrow 40 and the direction orthogonal to the direction, due to the effect of the rubbing treatment. When the display device is irradiated with interference light described later, the liquid crystal monomer is polymerized in a state where the liquid crystal monomer is oriented at the antinode of the standing wave due to the interference, and the liquid crystal monomer polymerized layer and the liquid crystal monomer are not polymerized. A first periodic structure in which layers (ie, liquid crystal material layers) are alternately stacked is formed. At this time, all liquid crystal monomers are not polymerized. That is, the irradiation amount is at most １ ／ or less of the irradiation amount necessary for completing the polymerization.

After the first periodic structure is formed by the above-described operation, the interference light is applied to the display device in the same manner as described above by changing the periodic interval of the standing wave according to the incident angle of the laser or using a laser having a different wavelength. Is irradiated, the liquid crystalline monomer is polymerized in the aligned state, and a second periodic structure is formed. As a result of these operations, two periodic structures can be produced in the same space, and the orientation directions of the two periodic structures are orthogonal.

In the display device of the second embodiment, when no voltage is applied, the liquid crystal and the liquid crystalline monomer in each periodic structure are oriented, so that there is no difference in refractive index.
Further, since there is no periodicity between the first and second periodic structures, reflected light due to Bragg reflection is not observed, and the structure is in a transparent state. However, a voltage is applied to the electrode pair 39 in a cycle faster than the response speed of the liquid crystal and for a time corresponding to a half cycle at a ratio as shown in FIG. 1C, and in the next half cycle, the second voltage is applied. When the magnitude is set to be equal to or less than the Freedericksz transition of the liquid crystal in a direction rotated by 90 ° in the ratio of FIG. 1C, the liquid crystal material 31 having the first periodic structure is re-oriented in the direction of the electric field, and the Bragg reflection occurs. The effect of observing the blue reflected light due to is produced. At this time, the liquid crystal material 33 having the second periodic structure does not reorient due to the electric field since the direction of the electric field is orthogonal to the orientation direction, and does not cause Bragg reflection. Furthermore, when the magnitude of the second voltage is equal to or larger than the Freedericksz transition, realignment of the liquid crystal material 33 occurs, and green reflected light due to Bragg reflection can be observed.

The liquid crystal display device according to the third embodiment of the present invention comprises the two substrates 35 and 3 shown in the first embodiment.
6, a mixture of a liquid crystal and a photocurable liquid crystalline monomer is sandwiched, and an electrode pair 39 is provided. The difference from the first embodiment is that a two-frequency liquid crystal whose dielectric anisotropy is positive or negative depending on the frequency of an applied voltage is used as the liquid crystal, and that no rubbing treatment is performed on both substrates 35 and 36. is there.

In the manufacture of the display device according to the third embodiment, the dielectric anisotropy of the liquid crystal is positively applied to the electrode pair 39 at a ratio as shown in FIG. An electric field of a certain frequency is applied. At this time, the injected liquid crystal and liquid crystalline monomer are oriented in the direction of the electric field, and the extraordinary optical axis of the liquid crystal is oriented in the direction of the electric field. In this state, when the display device is irradiated with interference light, which will be described later, as in the first embodiment, the first period in which the layer in which the aligned liquid crystalline monomer is polymerized and the liquid crystal material layer are alternately stacked is formed. A structure will be formed. At this time, all liquid crystal monomers are not polymerized. That is, the irradiation amount is at most １ ／ or less of the irradiation amount necessary for completing the polymerization.

After the first periodic structure is formed by the above-described operation, the electrode pair 39 is rotated by 90 ° in the same manner as described above in the ratio of FIG. When an electric field at a frequency at which the dielectric anisotropy of the liquid crystal becomes positive is applied, the extraordinary optical axis of the liquid crystal and the liquid crystalline monomer that has not yet been polymerized are oriented again in the direction of the electric field, and in that state interference light is applied to the display. Upon irradiation, a second periodic structure can be formed.
As a result of these operations, two periodic structures can be produced in the same space, and the orientation directions of the two periodic structures are orthogonal. The display device according to the third embodiment manufactured by this method has the same effect as the display device according to the first embodiment.

FIG. 3 is a schematic view illustrating a method for manufacturing a liquid crystal display device according to a fourth embodiment of the present invention. FIG.
, 41 is a display device, 42 is a laser beam, 43
Indicates a beam splitter, 44 and 45 indicate mirrors, and 46 indicates a laser.

In the fourth embodiment of the present invention, a mixture of a liquid crystal and a photocurable liquid crystalline monomer is sandwiched between substrates as shown in the first, second and third embodiments. This is the manufacture of the display device 41. A very small amount of a polymerization initiator (e.g., camphanquinone) is added to the mixture.

In the optical system shown in FIG.
The laser beam 42 from the m. argon laser 46 is split into two light beams by the beam splitter 43, and then the traveling direction of the beam is changed by mirrors 44 and 45 to be incident on the display device 41. At this time, the polarization direction of the two-beam laser beam is one of the alignment directions in which the liquid crystal and the liquid crystalline monomer are aligned by the rubbing process in the first and second embodiments, and the dielectric anisotropic direction in the third embodiment. A frequency at which the property is positive is applied to match the direction in which the liquid crystal and the liquid crystalline monomer are oriented.

As shown in FIG. 4, the polarization of the laser beam is set to P-polarized light 51 on a certain incident surface, and the P-polarized light 51 is incident from the normal direction of the display device (the crossing angle of the two light beams is 180 °) to cause interference in the display device. Then, a standing wave is generated in the polarization direction. At the antinodes of the standing wave, the photocurable liquid crystalline monomer polymerizes while maintaining the orientation, but no polymerization occurs at the nodes. That is, the ratio of the liquid crystal monomer increases in the polymerized portion, but increases in the non-polymerized portion, forming the first periodic structure. However, the irradiation dose is kept to such an extent that all the liquid crystalline monomers are not polymerized. That is, only the irradiation amount of at most １ ／ or less of the irradiation amount necessary for completing the polymerization is irradiated.

Next, as shown in FIG. 4, the crossing angle of the two laser beams is 90 °, the polarization direction is S polarization 52,
In the first embodiment, a frequency at which the dielectric anisotropy is positive is applied in the direction orthogonal to the above in the first embodiment, and in the direction perpendicular to the above in the second embodiment, the direction matches the direction in which the liquid crystal and the liquid crystalline monomer are oriented. Then, when the interference light is applied, a second periodic structure can be formed, and two periodic structures having different periodic intervals can be manufactured in the same space. By independently driving these two periodic structures, it is possible to obtain Bragg reflection of blue (the center wavelength is 488 nm) and green (the center wavelength is 514 nm).

FIG. 5 is a schematic diagram illustrating a method for manufacturing a liquid crystal display device according to a fifth embodiment of the present invention. FIG.
In the figure, 61 is a display device, 62 is a laser beam 1, 63
Is a beam splitter, 64 and 65 are mirrors, 66 is laser 1, 67 is laser 2, 68 is laser beam 2, 69
Indicates a shutter.

In the fifth embodiment of the present invention, a mixture of a liquid crystal and a photocurable liquid crystalline monomer is sandwiched between substrates as shown in the first, second and third embodiments. This is the manufacture of the display device 61. The difference from the fourth embodiment resides in that two lasers having different wavelengths are used. By using lasers of different wavelengths, the interference fringe intervals are different even if the incident angle on the display device is the same. Here, the incident angle of the laser beam is defined as the normal direction of the surface of the display device, and the polarization directions of the two laser beams are orthogonal to each other.
When one periodic structure is manufactured, one laser beam is blocked by an electronic shutter or the like, and the same operation as in the fourth embodiment of the present invention is sequentially performed, whereby the same display device can be manufactured.

FIG. 6 is a schematic diagram illustrating a method for manufacturing a display device according to a sixth embodiment of the present invention. In FIG. 6, 71 is a display device, 72 is a laser beam, 73 is a beam splitter 1, 74 and 75 are mirrors, 76 is a laser,
77 is the beam splitter 2, 78 is the beam splitter 3
Is shown.

The sixth embodiment of the present invention is the manufacture of a display device 51 in which a mixture of a liquid crystal and a photocurable liquid crystalline monomer is sandwiched between substrates as shown in the first embodiment. The difference from the fourth and fifth embodiments is that
It is to irradiate a display device with two lasers having different wavelengths at the same time. By using lasers of different wavelengths as in the fifth embodiment, the interference fringe intervals are different even if the incident angle to the display device is the same, and the incident angle of the laser beam is set to the normal direction of the display device surface, If two laser beams are simultaneously incident on the display device to produce two periodic structures with the polarization directions of both laser beams orthogonal to each other, it is possible to produce two periodic structures having different periodic intervals in the same space. it can.

FIG. 5 is a schematic diagram illustrating a method for manufacturing a liquid crystal display device according to a seventh embodiment of the present invention. In FIG. 5, 61 is a display device, 62 is a laser beam, 63 is a beam splitter, 64 and 65 are mirrors, and 66 and 67 are substrates.

The seventh embodiment of the present invention is directed to a display device 61 in which a mixture of a liquid crystal and a photocurable liquid crystalline monomer is sandwiched between substrates as described in the first and second embodiments. The manufacture of. The difference from the fourth embodiment is that the laser beam is split into four light beams, two light beams interfere with each other, and the intersection angles of the two light beam pairs are 180 ° and 90 °.
And the use of interference light having different interference fringe intervals. At this time, the polarization directions of the two light flux pairs are set to be the same, and the polarization directions between the two light fluxes are set to be orthogonal. Then, in the first and second embodiments of the present invention, when the two alignment directions orthogonal to each other and the polarization direction are made to coincide with each other and the display device is simultaneously irradiated with two interference lights, the liquid crystal monomers are respectively oriented in the alignment directions. While standing at the antinode portion of the standing wave to form a periodic structure having two different periodic intervals. The display device according to the seventh embodiment manufactured by this method can expect the same effect as the display device according to the first embodiment.

In the above embodiment, the description has been made assuming that the intersection angle of the two light beams is 180 ° or 90 °.
It is not limited to this. The direction of the layer can also be controlled by controlling the directions of the two light beams during fabrication. That is, a plurality of Bragg reflected lights can be concentrated in a certain observation direction or reflected in different directions.

In the above embodiment, two or more
Although a periodic structure having two different periodic intervals has been described as an example, the present invention is not limited to this, and it is possible to form three or more periodic structures in the same space using the above embodiment. Obviously, this makes it possible to further increase the light use efficiency in the same space. Also,
The electrode pair material for independently driving these periodic structures is not limited, and a transparent electrode typified by ITO (indium tin oxide) or a metal conductor such as aluminum can be used.

As described above, the present invention has been specifically described based on the embodiments. However, the present invention is not limited to the above-described embodiments, and can be variously modified without departing from the gist thereof.

[0063]

The effects of the present invention will be briefly described as follows. In the liquid crystal display device of the present invention, a plurality of periodic structures with variable refractive index modulation are formed in the same space, and each periodic structure has a layer made of a liquid crystal material whose orientation can be controlled by an electric field, and It has a multilayer structure in which layers of photocurable materials having optical anisotropy that cannot be controlled are alternately stacked, and can be driven independently, and each periodic structure selectively reflects different wavelength bands. And a plurality of electrode pairs for driving independently of each other. In addition, if necessary, an electric field that is substantially unidirectional with a period faster than the response speed of the liquid crystal,
Apply in a different direction. As a result, each periodic structure shows the difference in the refractive index between a layer of a liquid crystal material whose orientation can be controlled by an electric field and a layer of a photocurable material having optical anisotropy whose orientation can not be controlled by an electric field. Each wavelength can be changed independently by the electrode pair provided for each of the periodic structures, and different wavelength bands can be reflected by the refractive index period of each periodic structure, so that the light use efficiency in the same space can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a configuration of a liquid crystal display device according to the present invention.

FIG. 2 is a diagram illustrating an example of a display operation of the liquid crystal display device according to the present invention.

FIG. 3 is a diagram showing an example of an optical system in a method for manufacturing a liquid crystal display device according to the present invention.

FIG. 4 is a diagram illustrating an example of a polarization direction of a laser beam in the method for manufacturing a liquid crystal display device according to the present invention.

FIG. 5 is a diagram showing an example of an optical system when two lasers are used in the method for manufacturing a liquid crystal display device according to the present invention.

FIG. 6 is a diagram showing an example of an optical system when a laser beam of four light beams is used in the method of manufacturing a liquid crystal display device according to the present invention.

FIG. 7 is a schematic view of a conventional liquid crystal display device.

FIG. 8 is a view for explaining a multilayer structure of a conventional liquid crystal display element.

9 is a diagram showing the major axis direction of each layer when no electric field is applied and when the multilayer structure shown in FIG. 8 is applied.

[Explanation of symbols]

31: liquid crystal material in first periodic structure 32: photocurable material in first periodic structure 33: liquid crystal material in second periodic structure 34: photocurable material in second periodic structure 35: liquid crystal material and light Substrate sandwiching mixture of curable material 36 Substrate sandwiching mixture of liquid crystal material and photocurable material 37 Electrode pair for applying electric field to first periodic structure 38 Applying electric field to second periodic structure Electrode pair 39: reciprocal lattice vector of second periodic structure 41: liquid crystal display device 42: laser beam 43: beam splitter 44: mirror 45: mirror 46: laser 51: polarization direction of laser beam (P polarization) 52: Polarization direction of laser beam (S-polarized light) 53 Cross angle of two-beam laser beam 54 Cross section of liquid crystal display device 61 Liquid crystal display device 62 Laser beam 1 DESCRIPTION OF SYMBOLS 3 ... Beam splitter 64 ... Mirror 65 ... Mirror 66 ... Laser 1 67 ... Laser 2 68 ... Laser beam 2 69 ... Shutter 71 ... Liquid crystal display 72 ... Laser beam 73 ... Beam splitter 1 74 ... Mirror 75 ... Mirror 76 ... Laser 77 ... Beam splitter 2 78 Beam splitter 3 101 Transparent substrate 102 Transparent substrate 103 Transparent electrode 104 Transparent electrode 105 Liquid crystal droplet 106 Polymer material 107 Power supply 108 Incident light 109 Reflected light 110 Transmitted light Reference Signs List 20 multilayer structure 21 layer whose major axis direction is oriented in a certain direction 22 layer whose major axis direction is oriented in a parallel direction 23 layer whose major axis direction is oriented in a certain direction 24 direction in which the major axis direction is orthogonal Layer suitable for

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G09G 3/18 G09G 3/18 5C006 (72) Inventor Hiroshi Hayama 5-7-1 Shiba 5-chome, Minato-ku, Tokyo F-term in NEC Corporation (reference) 2H088 GA06 GA15 HA13 HA20 HA28 JA08 LA02 MA06 MA20 2H089 HA27 HA32 KA08 KA20 QA16 RA04 TA07 TA12 TA15 TA17 TA18 2H090 KA04 LA04 LA09 LA11 LA16 LA20 MA15 MB14 2H092 MA30 PA12 PA06 2H093 NA25 ND08 NE06 NF04 5C006 BB11 BD03 EC11 FA54

Claims (15)

[Claims] A periodic structure in which a refractive index is modulated is formed in a plurality of spaces. Each periodic structure includes a layer made of a liquid crystal material whose alignment direction can be controlled by an electric field and a photo-curing layer whose alignment direction cannot be controlled by an electric field. Characterized by a multilayer structure in which layers made of conductive materials are alternately stacked, and an electrode pair is provided for selectively reflecting different wavelength bands in each periodic structure and independently driving the same. Display device. 2. The liquid crystal display device according to claim 1, wherein a liquid crystal material having a negative dielectric anisotropy is used as a liquid crystal material, and a liquid crystalline monomer which is an optically anisotropic material is used as a photocurable material. 3. A liquid crystal material comprising a dual-frequency liquid crystal whose dielectric anisotropy becomes positive or negative depending on the frequency of an applied voltage, and a liquid crystal monomer which is an optically anisotropic material is used as a photocurable material. The liquid crystal display device according to claim 1. 4. The liquid crystal display according to claim 1, wherein two periodic structures are formed in the same space, and the orientation directions between the periodic structures are orthogonal to each other. apparatus. 5. The liquid crystal according to claim 1, wherein three periodic structures are formed in the same space, and the alignment directions between the periodic structures are different by 60 °. Display device. 6. A method for manufacturing a liquid crystal display device according to claim 1, wherein a mixture of a liquid crystal material and a photocurable material having optical anisotropy is sandwiched between substrates. And a step of irradiating the sandwiched substrate with a plurality of interference lights to produce a multi-layered structure in which a layer of a photocurable material polymerized and a layer of a non-polymerized material are alternately stacked. A method of manufacturing a liquid crystal display device. 7. The laser beam of the four light beams, two of which are incident on the incident surface.
7. The method according to claim 6, wherein the light beam is P-polarized light, the two light beams interfere with each other, and the remaining two light beams interfere with S-polarized light. 8. The method for manufacturing a liquid crystal display device according to claim 6, wherein incident angles of the respective polarized lights are different. 9. The method according to claim 1, wherein two laser beams emitting different single wavelengths are used, each laser beam is split into two light beams, and the two split light beams interfere with each other to cure the photocurable material. 7. The method for manufacturing a liquid crystal display device according to item 6. 10. The liquid crystal display device according to claim 9, wherein the polarization of two light beams branched from one laser beam with respect to the incident surface is P polarization, and the polarization of the remaining two light beams is S polarization. Manufacturing method. 11. The method according to claim 9, wherein the crossing angle of the two light beams branched from one laser beam is an angle that is not the same as the interval between interference fringes produced by another laser beam. A method for manufacturing a liquid crystal display device. 12. A method of driving a liquid crystal display device according to claim 1, wherein different voltages are applied to a plurality of electrode pairs to generate a substantially unidirectional electric field. A method for driving a liquid crystal display device. 13. The method for driving a liquid crystal display device according to claim 1, wherein different voltages are applied to a plurality of pairs of electrodes for a predetermined time, and a substantially unidirectional electric field is applied. After that, the operation of changing the value of the applied voltage and generating an electric field in a substantially one direction in a direction different from the electric field for a certain period of time is repeated, and as an average of the voltage application time, the operation is substantially performed in a plurality of directions. A method for driving a liquid crystal display device, wherein an electric field is generated. 14. The driving method for a liquid crystal display device according to claim 12, wherein the number of electrode pairs is four. 15. The driving method of a liquid crystal display device according to claim 13, wherein substantially a plurality of directions are two orthogonal directions.