JPH11149069A - Liquid crystal device and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide means capable of embodying a liquid crystal device of a high polymer dispersion type capable of lessening scattering directivity without increasing driving voltage. SOLUTION: This liquid crystal device is constituted by disposing a composite layer of a liquid crystal high polymer formed by dispersing high polymers (not shown in Fig.) and liquid crystal molecules 135 with each other between a pair of substrates 100a and 100b coated with alignment layers 120a, 120b not subjected to rubbing treatments. Since these alignment layers 120a, 120b are not subjected to the rubbing treatments, plural domains are formed on the substrate surfaces and the alignment directions of the liquid crystal molecules are set in the specified direction within the domains but are random between the domains. Further, the liquid crystal molecules are aligned by regulating the twist angle thereof to a prescribed value, such as 90 deg., between the substrates.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a liquid crystal device in which a liquid crystal and a polymer are mutually dispersed, and an electronic apparatus equipped with the liquid crystal device.

[0002]

2. Description of the Related Art A conventional polymer-dispersed liquid crystal device forms a liquid crystal polymer composite layer in which liquid crystal and a polymer are mutually dispersed between a pair of substrates having an alignment film coated on electrodes. Was composed. When no electric field is applied, since the liquid crystal having the refractive index anisotropy is oriented in the same direction as the polymer having the same refractive index anisotropy, the liquid crystal and the polymer are refracted in a direction perpendicular to both substrates. The rates match and the incident light can be transmitted.

On the other hand, when an electric field is applied to both electrodes, the orientation of the polymer remains unchanged, whereas the liquid crystal is
That is, since the liquid crystal and the polymer are oriented in a direction perpendicular to the two substrates, the refractive indices of the liquid crystal and the polymer are different, and the incident light is scattered. Conventional polymer-dispersed liquid crystal devices are configured to transmit and scatter in this manner.To reduce the scattering directivity of the polymer-dispersed liquid crystal device, the twist angle of the liquid crystal must be increased. Was set.

[0004]

However, if the twist angle of the liquid crystal is increased in order to reduce the scattering directivity of the polymer dispersed liquid crystal device, the driving voltage for bringing the polymer dispersed liquid crystal device into a scattering state is increased. And the driving voltage is large, which has become a problem, in conjunction with the recent demand for power saving.

On the other hand, in order to reduce the driving voltage, it is necessary to reduce the twist angle of the liquid crystal. As a result, the scattering directivity cannot be reduced.

The present invention has been made to solve such a conventional problem, and an object of the present invention is to provide a polymer-dispersed liquid crystal device capable of reducing scattering directivity without increasing driving voltage. Is to provide means capable of realizing the above.

[0007]

In order to achieve the above object, according to the first aspect of the present invention, a liquid crystal and a polymer are dispersed in each other, and the liquid crystal and the polymer are dispersed in response to application of an electric field and no application of an electric field.
A liquid crystal device configured so that the transmission state is controlled, wherein a liquid crystal polymer composite layer in which liquid crystal and a polymer are mutually dispersed is provided between a pair of substrates coated with an alignment film, and further,
The liquid crystal is characterized in that the liquid crystal is in a random alignment state on the surfaces of both substrates and is aligned with a twist angle regulated between the substrates at a predetermined value.

According to this, the liquid crystal is randomly aligned on the surface of the substrate and is aligned with the twist angle being regulated to a predetermined value between the substrates. Therefore, the liquid crystal is scattered without increasing the twist angle. Since the directivity can be reduced and the twist angle does not need to be increased, the electric field intensity for bringing the liquid crystal device into the scattering state can be reduced.

Further, the twist angle of the liquid crystal is set in a range of 30 degrees to 120 degrees. By setting the twist angle of the liquid crystal molecules in this range, the electric field intensity for setting the scattering state can be reduced.
More preferably, an optimal scattering state can be obtained by setting the twist angle of the liquid crystal to approximately 60 degrees.

Further, assuming that the cell thickness between the substrates of the liquid crystal device is d and the chiral pitch of the liquid crystal is p, 1/12 ≦
The amount of the chiral agent added to the liquid crystal is set so that d / p ≦ １ ／.

[0011] According to this, the number of domains (regions on the substrate surface where liquid crystals having aligned directions are present) is appropriately controlled, unnecessary scattering between domains is reduced, and the invention is applied to a liquid crystal device. This makes it possible to manufacture a liquid crystal device with improved contrast and the like.

Regarding the number of domains, by forming 30 to 150 domains / mm ² in the liquid crystal device, unnecessary scattering between domains is reduced, and a liquid crystal device with improved contrast is provided. be able to. More preferably, the domain formed in the liquid crystal device is 5 domains.
It is characterized by being formed from 0 to 100 pieces / mm ² .

Further, by mounting such a liquid crystal device in an electronic device, a liquid crystal device having excellent characteristics can be arranged in various portable devices and the like, and an electronic device with low power consumption can be obtained.

[0014]

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

FIG. 1 is a schematic illustration of the structure of a polymer-dispersed liquid crystal device according to an embodiment of the present invention. In addition,
Although the polymer has a particle shape and is dispersed in the liquid crystal, the dispersed state of the polymer is not shown in the figure for easy understanding.

This polymer-dispersed liquid crystal device has a polymer (not shown) between a pair of substrates 100a and 100b coated with alignment films 120a and 120b that are not subjected to rubbing.
And liquid crystal molecules 135 are mutually dispersed, and a liquid crystal polymer composite layer in which a polymer is dispersed in liquid crystal is provided.

Normally, the substrate 100a (100b) of the polymer dispersion type liquid crystal device and the alignment film 120a (120
An electrode formed on the substrate 100a (100b) is interposed between the liquid crystal device and the device b), thereby forming a polymer-dispersed liquid crystal device.

In this polymer-dispersed liquid crystal device, when no electric field is applied, the liquid crystal having the refractive index anisotropy is oriented in the same direction as the polymer having the same refractive index anisotropy. The refractive indices of the liquid crystal and the polymer in the vertical direction match, so that incident light can be transmitted.

On the other hand, when an electric field is applied to both electrodes, the orientation of the polymer remains unchanged, while the liquid crystal is
That is, since the liquid crystal and the polymer are oriented in a direction perpendicular to the two substrates, the refractive indices of the liquid crystal and the polymer are different, and the incident light is scattered. In such a liquid crystal device, display is performed by controlling the applied voltage between a voltage non-applied state and a voltage applied state. It is also possible to control the degree of scattering based on the applied voltage.

Since the rubbing treatment is not performed on the alignment films 120a and 120b of the polymer dispersion type liquid crystal device shown in FIG. 1, the liquid crystal molecules on the substrate surface are randomly arranged. Then, a plurality of domains (one of the domains is indicated by reference numeral 10 in the figure) is formed, and the alignment direction of the liquid crystal molecules is constant within the domains, but is random between the domains.

Further, between the substrates, the liquid crystal molecules are arranged at a twist angle defined by the chiral agent, and the liquid crystal molecules are aligned with the twist angle regulated to a predetermined value such as 90 °. To set the twist angle to a predetermined value,
A liquid crystal cell may be manufactured by adding a predetermined amount of a chiral agent to the liquid crystal. It should be noted that the twist angle is not limited to 90 °, but can be set to around 60 °. Since the drive voltage is increased and the power consumption is increased by increasing the twist angle, it is desirable that the twist angle be as small as possible.

As described above, the liquid crystal molecules are in a random alignment state on the substrate surface, and are aligned with the twist angle regulated to a predetermined value between the substrates. Therefore, the liquid crystal molecules can be scattered without increasing the twist angle. It is possible to reduce the performance. Further, since the twist angle does not need to be increased, when this liquid crystal cell is applied to various liquid crystal devices, it is possible to reduce the electric field intensity for bringing the liquid crystal device into a scattering state.

Next, a method of manufacturing a polymer-dispersed liquid crystal device manufactured using such a polymer-dispersed liquid crystal cell will be described.

In this polymer-dispersed liquid crystal device, a liquid crystal mixed material comprising a liquid crystal, a polymer precursor and a chiral agent is injected between a pair of substrates on which electrodes are formed, and the mixture is irradiated with ultraviolet rays. Is produced by photopolymerizing a polymer precursor to precipitate a polymer in a liquid crystal.

More specifically, a step of forming an electrode on a substrate, a step of forming an alignment film on a substrate, a step of bonding substrates, a step of injecting a liquid crystal mixed material between a pair of substrates, Irradiating the liquid crystal mixed material injected between the substrates with ultraviolet rays.
Here, a method for manufacturing the liquid crystal device will be described more specifically with reference to FIG.

First, in step 100, substrates 100a, 100a manufactured by cutting glass or the like into a desired size are manufactured.
An electrode having a predetermined pattern is formed using a patterning technique for each of b. When the liquid crystal device of the present invention is used as a reflection type, an electrode formed on one substrate is formed of a metal material. Then, it is formed of a material having reflection characteristics. Examples of the metal material include materials having high reflectance characteristics such as Cr, Al, Ag, Mg, and alloys thereof, and by using these materials, an electrode having reflection characteristics can be formed.

Next, in step 110, on both electrodes,
The alignment films 120a and 120b are formed by applying polyimide or the like. At this time, the rubbing treatment which is usually performed is performed by the alignment film 120.
a, 120b. Note that, in the present invention, an alignment film in which liquid crystal molecules are aligned in a substantially horizontal direction with respect to the temperature is used. For example, Optmer AL1254 manufactured by Japan Synthetic Rubber Co., Ltd. was used.

Next, in step 120, the substrate 100
a, 100b is subjected to a seal printing process. When forming the sealing material, an injection hole for the liquid crystal mixed material is provided.

Further, in step 130, both substrates 11
0a and 110a are assembled facing each other. The gap between substrates (or cell thickness) was set to 6 μm in this embodiment.

Then, in step 140, a liquid crystal mixed material is injected from an injection hole provided at the time of forming the sealing material.
Thereafter, the injection hole was sealed. As a liquid crystal, T
92.9% by weight of L213, 7% by weight of biphenyl-4-yl methacrylate as a polymer precursor, and 0.1% by weight of R-1011 manufactured by Merck as a chiral agent were used.

Finally, the liquid crystal mixed material is irradiated with ultraviolet rays to precipitate a polymer. Note that the amount of the chiral agent added to the liquid crystal mixed material may be determined so that the twist angle of the liquid crystal molecules between the substrates is regulated to a predetermined value and aligned. The conditions for polymerization by ultraviolet irradiation were as follows: a black light was used as a light source and irradiation was performed at an illuminance of 3 mW / cm ^{2 for} 30 minutes.

According to such a manufacturing process, a rubbing treatment is not performed on the alignment film, and a liquid crystal polymer composite layer in which a desired amount of a chiral agent is added and a liquid crystal and a polymer are mutually dispersed is formed. Since the liquid crystal is formed between the substrates 100a and 100b, the liquid crystal is in a random alignment state on the substrate surface, and the liquid crystal is aligned with the twist angle regulated to a predetermined value between the substrates.

Next, an experiment for examining the scattering directivity of the polymer-dispersed liquid crystal device thus manufactured will be described.

FIG. 3 is a schematic explanatory view of an experimental system for examining the scattering directivity of a liquid crystal device in a scattering state. In addition,
Here, each of the substrates 100a and 100b and the alignment film 12
0a and 120b, respectively, between the substrates 100a and 10b.
The electrodes 110a and 110b formed on the Ob are interposed.

In this experimental system, the liquid crystal device is configured to be rotatable around a center point as a rotation center. Assuming that the longitudinal direction of the substrate 100a (100b) passes through the center point and the direction orthogonal to the y-axis passes through the center point is the x-axis, the plane including the y-axis and perpendicular to the substrate 100a. so,
Light emitted from an LD (laser diode) 200 is collimated by a collimating lens 210 and applied to the center point, and a photomultiplier is provided so that light reflected from the center point is received in the normal direction of the substrate 100a. The angle formed between the optical path of the collimated light beam and the optical path of the light beam received by the photomultiplier 220 is set to be constant at 30 °.

Now, an electric field is applied to the liquid crystal device to make it a scattering state, and the in-plane rotation angle when the liquid crystal device is rotated in the horizontal plane with the center point as the center of rotation is θ (in-plane at an appropriate reference position). FIG. 4 shows the rotation angle θ = 0 °) and the light receiving level at the photomultiplier 220 expressed as the reflection level at the standard white plate as “100”.

As can be seen with reference to FIG. 4, the polymer-dispersed liquid crystal device according to this embodiment can secure a scattering state and reduce scattering directivity, regardless of the direction from which light enters. It becomes possible.

Next, another embodiment of the present invention will be described.

The polymer-dispersed liquid crystal device manufactured by using the polymer-dispersed liquid crystal cell described with reference to FIG. 1 has the advantage that the applied electric field strength is small and the scattering directivity is small, The off-level, which is the level of reflected light, rises, making it difficult to ensure a contrast ratio of a conventional product, for example, a contrast ratio of about 9.5 for a rubbed cell (270 ° twist). . This is because unnecessary scattering occurs between domains formed on the substrate surface.

Therefore, it has been proposed to adjust the contrast ratio by controlling the number of domains by adjusting the amount of the chiral agent added, thereby adjusting the contrast ratio. Assuming that the cell thickness is d and the chiral pitch of the liquid crystal is p, “d / p” is a parameter uniquely corresponding to the amount of the chiral agent added.

Therefore, by adjusting the amount of the chiral agent added,
FIG. 5 shows how the number of domains and the contrast ratio are examined when the parameters are changed. The left vertical axis indicates the number of domains within the area of a square of 350 (μm) per side, and the right vertical axis indicates the contrast ratio. In addition,
The cell thickness d was 5 (μm), and the electrode surface was a square having a side of 50 (mm).

The contrast is made equal to the conventional one, that is,
In order to attain “9.5” or more, the range of the parameter “d / p” may be set to 1/12 ≦ d / p ≦ １ ／, and 1/1
It was confirmed that the chiral agent should be added in such an amount that 2 ≦ d / p ≦ ｐ. In this manner, by adjusting the amount of the chiral agent added, the number of domains can be controlled to reduce unnecessary scattering between domains, and a liquid crystal device with improved contrast and the like can be manufactured.

In order to control the number of domains as described above, in step 140 of FIG. 2, when the liquid crystal mixed material is injected, an additive such that 1/12 ≦ d / p ≦ １ ／ is satisfied. An amount of chiral agent may be added to the liquid crystal, and in the remaining steps, the same processing as described above with reference to FIG. 2 may be performed.

As described above, according to the embodiment of the present invention, the liquid crystal molecules 135 correspond to the substrates 100a, 10b.
0b is in a random orientation state on the surface, and between the substrate 100a and the substrate 100b, the twist angle is regulated to a predetermined value, so that the scattering directivity is reduced without increasing the twist angle. It is not necessary to increase the twist angle, so that the driving voltage can be reduced.

An electronic apparatus to which the liquid crystal device as described in the present application is applied will be described below.

As the electronic equipment, a liquid crystal projector shown in FIG. 6, a personal computer (PC) and an engineering workstation (EWS) for multimedia shown in FIG. 7, a pager shown in FIG. 8, or a mobile phone, a word processor, a television, Viewfinder type or monitor direct view type video tape recorder, electronic organizer,
Examples include an electronic desk calculator, a car navigation device, a POS terminal, and a device equipped with a touch panel.

FIG. 6 is a schematic configuration diagram showing a main part of the projection display device. In the figure, 10 is a light source, 13 and 14 are dichroic mirrors, 15, 16 and 17 are reflection mirrors, 1
8, 19, and 20 indicate relay lenses, 22, 23, and 24 indicate liquid crystal light valves, 25 indicates a cross dichroic prism, and 26 indicates a projection lens. An aperture 28 is formed on the projection lens 26. The above-described liquid crystal device of the present invention is a liquid crystal device that controls transmission and scattering by a difference in refractive index between liquid crystal and a polymer. Therefore, in the case of the liquid crystal device of the present invention used as a light valve, it is necessary to stop the light scattered by the liquid crystal device by the stop 28 formed in the projection lens 26. With such a configuration, the liquid crystal device that controls the light transmission / scattering state as in the present application can be used as a light valve.

The light source 10 comprises a lamp 11 such as a metal halide and a reflector 12 for reflecting light from the lamp. Dichroic mirror 13 that reflects blue light and green light
Transmits red light of the white light flux from the light source 10 and reflects blue light and green light. The transmitted red light is reflected by the reflection mirror 17 and enters the red light liquid crystal light valve 22.

On the other hand, the green light of the color light reflected by the dichroic mirror 13 is reflected by the green light reflecting dichroic mirror 14 and is incident on the liquid crystal light valve 23 for green light. On the other hand, the blue light also passes through the second dichroic mirror 14. For blue light, in order to prevent light loss due to a long optical path, a light guide means 21 including a relay lens system including an incident lens 18, a relay lens 19, and an exit lens 20 is provided. The light enters the liquid crystal light valve 24 for light. The three color lights modulated by the respective light valves enter the cross dichroic prism 25. This prism has four right-angle prisms bonded together, and a dielectric multilayer film that reflects red light and a dielectric multilayer film that reflects blue light are formed in a cross shape on the inner surface. The three color lights are combined by these dielectric multilayer films to form light representing a color image. The synthesized light is projected on a screen 27 by a projection lens 26 which is a projection optical system, and an image is enlarged and displayed.

The personal computer 120 shown in FIG.
0 is a main body 1204 having a keyboard 1202;
A liquid crystal display screen 1206.

The pager 1300 shown in FIG. 8 includes a liquid crystal display substrate 1304, a light guide 1306 provided with a backlight 1306a, a circuit board 1308, and first and second shield plates 1310 and 131 in a metal frame 1302.
It has two, two elastic conductors 1314 and 1316, and a film carrier tape 1318. Two elastic conductors 1314 and 1316 and a film carrier tape 131
Reference numeral 8 denotes a connection between the liquid crystal display substrate 1304 and the circuit substrate 1308.

Here, the liquid crystal display substrate 1304 has liquid crystal sealed between two transparent substrates 1304a and 1304b, thereby forming at least a dot matrix type liquid crystal display panel. A driving circuit or a display information processing circuit in addition to the driving circuit can be formed on one of the transparent substrates (these are not shown).
Circuits not mounted on the liquid crystal display substrate 1304 are external circuits of the liquid crystal display substrate, and in the case of FIG.
08.

FIG. 9 shows the structure of the pager, and therefore requires a circuit board 1308 in addition to the liquid crystal display substrate 1304. In this case, a liquid crystal display device is used as one component for electronic equipment. When a display driving circuit or the like is mounted on a transparent substrate, the minimum unit of the liquid crystal display device is the liquid crystal display substrate 1304. Alternatively, a structure in which the liquid crystal display substrate 1304 is fixed to a metal frame 1302 serving as a housing can be used as a liquid crystal display device which is one component for electronic devices. Further, in the case of a backlight type, the liquid crystal display substrate 1 is placed in a metal frame 1302.
The liquid crystal display device can be configured by incorporating the light guide 304 and the light guide 1306 provided with the backlight 1306a. Instead, a polyimide tape 132 having a metal conductive film formed on one of two transparent substrates 1304a and 1304b constituting a liquid crystal display substrate 1304 is used.
(TCP) with IC chip 1324 mounted on
Carrier Package) 1320 can be connected to use as a liquid crystal display device, which is one component of electronic equipment.

The present invention is not limited to the above embodiment, and various modifications can be made within the scope of the present invention. For example, the present invention is not limited to being applied to the driving of the above-described various liquid crystal panels, but is also applicable to electroluminescence and plasma display devices.

FIG. 10 is an external view showing an example of electronic equipment using the liquid crystal device of the present invention as a reflection type liquid crystal device (hereinafter, also referred to as a liquid crystal panel).

FIG. 10A is a perspective view showing a mobile phone. 1000 denotes a mobile phone body, of which 100
Reference numeral 1 denotes a liquid crystal display unit using the reflection type liquid crystal panel of the present invention.

FIG. 10B is a diagram showing a wristwatch-type electronic device. 1100 is a perspective view showing the watch main body. 1
Reference numeral 101 denotes a liquid crystal display unit using the reflection type liquid crystal panel of the present invention. Since this liquid crystal panel has higher definition pixels than a conventional clock display unit, it can also display television images, and can realize a wristwatch type television.

FIG. 10C shows a portable information processing apparatus such as a word processor or a personal computer. 1200 denotes an information processing device, 1202 denotes an input unit such as a keyboard,
Reference numeral 06 denotes a display unit using the reflective liquid crystal panel of the present invention.
Reference numeral 04 denotes an information processing apparatus main body. Since each electronic device is a battery-driven electronic device, the use of a reflective liquid crystal panel without a light source lamp can extend the battery life. Further, since the peripheral circuit can be built in the panel substrate as in the present invention, the number of components can be greatly reduced, and the weight and size can be further reduced.

[0059]

As described above, according to the present invention,
The liquid crystal is randomly aligned on the surface of the substrate, and the liquid crystal is aligned with the twist angle regulated to a predetermined value between the substrates, so the scattering directivity can be reduced without increasing the twist angle. And the intensity of the electric field for bringing the liquid crystal device into the scattering state can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating the structure of a polymer-dispersed liquid crystal cell according to an embodiment of the present invention.

FIG. 2 is an explanatory view illustrating a manufacturing process of the polymer-dispersed liquid crystal device according to the embodiment of the present invention.

FIG. 3 is a schematic explanatory view of an experimental system for measuring the effect of the polymer-dispersed liquid crystal device according to the embodiment of the present invention.

FIG. 4 is an explanatory diagram showing an effect of the polymer-dispersed liquid crystal device according to the embodiment of the present invention.

FIG. 5 is an explanatory diagram of the dependence of the characteristics of the polymer-dispersed liquid crystal device according to the embodiment on the amount of chiral agent added.

FIG. 6 is a diagram illustrating an electronic apparatus equipped with the liquid crystal device of the present invention.

FIG. 7 is a diagram illustrating an electronic apparatus equipped with the liquid crystal device of the present invention.

FIG. 8 is a diagram showing an electronic apparatus equipped with the liquid crystal device of the present invention.

FIG. 9 is a diagram schematically illustrating an electronic apparatus according to the invention.

FIG. 10 is a diagram showing an electronic device equipped with the liquid crystal device of the present invention.

[Explanation of symbols]

 10 Domain 100a Substrate 100b Substrate 110a Electrode 110b Electrode 120a Alignment film 120b Alignment film 130 Liquid crystal 135 Liquid crystal molecule 140 Polymer 200 LD (Laser diode) 210 Collimating lens 220 Photomultiplier

Claims (7)

[Claims] 1. A liquid crystal device in which a liquid crystal and a polymer are mutually dispersed, and a scattering state and a transmission state are controlled according to application and non-application of an electric field. A liquid crystal polymer composite layer in which a liquid crystal and a polymer are mutually dispersed is provided between a pair of substrates, and the liquid crystal is in a random alignment state on the surfaces of both substrates and twisted between the substrates. A liquid crystal device characterized in that the angle is regulated to a predetermined value and aligned. 2. A twist angle of the liquid crystal is from 30 degrees to 120 degrees.
2. The liquid crystal device according to claim 1, wherein the liquid crystal device is set in a range of degrees. 3. The liquid crystal device according to claim 2, wherein the twist angle of the liquid crystal is set to approximately 60 degrees. 4. The liquid crystal device according to claim 1, wherein d is the cell thickness between the substrates, and p is the chiral pitch of the liquid crystal, where 1/12 ≦ d / p ≦
2. The liquid crystal device according to claim 1, wherein the amount of the chiral agent added to the liquid crystal is set to 1/3. 5. The liquid crystal device according to claim 5, wherein said liquid crystal device has 30 domains.
^2. The liquid crystal device according to claim 1, wherein the liquid crystal device is formed in a size of from 150 to 150 / mm <2>. 6. The liquid crystal device according to claim 5, wherein said liquid crystal device has 50 domains.
The liquid crystal device according to claim 5, wherein the number of the liquid crystal devices is from 100 / mm ² . 7. An electronic apparatus comprising the liquid crystal device.