JP3219454B2 - Ferroelectric liquid crystal display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ferroelectric liquid crystal display device, and more particularly, to a ferroelectric liquid crystal display device which is resistant to external impact and pressure.

[0002]

2. Description of the Related Art In recent years, a liquid crystal optical element using a ferroelectric liquid crystal as a liquid crystal material, controlling the orientation of the liquid crystal to a high degree, and sandwiching the liquid crystal material between two substrates provided with electrodes has been developed. It responds quickly to external stimuli such as electric fields,
Attention has been paid to its excellent properties such as excellent contrast ratio and the like, and it has been actively studied as a liquid crystal display element, a liquid crystal storage element and the like. In the ferroelectric liquid crystal described above, it is necessary that the liquid crystal molecules form a layer structure and are stably aligned in order to maintain the device function. But,
When shock or pressure is applied to the liquid crystal from the outside, the orientation of the liquid crystal molecules is disturbed. In particular, when a shock or pressure is applied, the molecular orientation is easily disturbed and the display function is impaired. In addition, the disorder of the molecular orientation of the liquid crystal in the ferroelectric low-molecular liquid crystal cannot be recovered by itself, and becomes a permanent defect.

[0003]

In view of the above circumstances, in order to prevent the alignment of liquid crystal molecules from being disturbed,
For example, JP-A-2-214821 discloses a structure in which a cushion material is provided between a support base and a liquid crystal panel to absorb impact, and JP-A-3-152513 discloses a structure in which an adhesive layer (sealing portion) is provided on a panel. It is made of silicon resin and has a structure to absorb the impact at this part. However, JP
No. 214821 has a problem that the shape of a support having a display window is complicated and processing is complicated, and there is a problem that a glass plate is used to easily break the glass and bring about a risk. Japanese Patent Application Laid-Open No. 3-152513 has a problem that when the panel is small, the adhesive layer on the outer peripheral portion can absorb the impact, but when the panel is large, the impact at the center of the panel cannot be absorbed. . Furthermore, the conventional liquid crystal display element does not have anti-glare processing on the substrate, so the display surface is easily reflected, especially when the display surface is curved, light reflection is severe, it is very difficult to read, and eyestrain is large. There was a problem of becoming.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems. The present invention aims at improving the display performance by preventing the disorder of the molecular orientation by increasing the mechanical shock resistance and improving the display performance. It is an object of the present invention to provide a ferroelectric liquid crystal display element which has been subjected to an antiglare process to prevent light reflection on a display surface. It is another object of the present invention to provide a ferroelectric liquid crystal display element having a high degree of freedom by achieving an improvement in impact resistance using a resin substrate or the like.

[0005]

In order to achieve the above object, a ferroelectric liquid crystal display device of the present invention is a liquid crystal display device in which a ferroelectric liquid crystal is sandwiched between two transparent resin substrates having a transparent conductive film. In the above, the two transparent resin substrates
mm, and a protective layer formed of an elastic member having a thickness of 1 to 5 mm made of transparent silicon rubber or fluoro rubber on the display side surface of the display side substrate. There is. Further, in the ferroelectric liquid crystal display device of the present invention, the protective layer is a ferroelectric liquid crystal display device made of silicon gel. Also,
The ferroelectric liquid crystal display device of the present invention is a ferroelectric liquid crystal display device in which a shock absorbing layer is formed between a back substrate and a support member of the two transparent resin substrates.

According to the ferroelectric liquid crystal display device having the above-described structure, even if a shock or pressure is directly applied from the display surface side of the ferroelectric liquid crystal display device, these are formed on the display substrate or the upper portion of the display substrate. The ferroelectric liquid crystal display device is not adversely affected by the protection layer. When pressure or shock is applied to the device to which the ferroelectric liquid crystal display device is attached, the shock is absorbed by a shock absorber provided between the back substrate and the support member of the device, and the ferroelectric liquid crystal display device is absorbed. Does not reach to. Therefore, there is no disturbance in the molecular orientation. Further, even if the display surface is a curved surface, light is not reflected, and the displayed contents are easy to read.

Hereinafter, the ferroelectric liquid crystal display device of the present invention will be described in detail. FIG. 1 shows a first embodiment of the present invention, in which a ferroelectric liquid crystal 1 is sandwiched between two resin substrates 2 and 3, a display substrate 2 has a thickness of 0.2 to 5 mm, and a back substrate 3 has a thickness of 0.2 to 5 mm.
The thickness is 2 mm or less.

Liquid crystal material 1 sandwiched between two substrates 2 and 3
Is not particularly limited, but it is preferable to use a ferroelectric liquid crystal material. As a ferroelectric liquid crystal state,
Ferroelectric low-molecular liquid crystal, ferroelectric polymer liquid crystal, or a mixture thereof, and the like. Here, the ferroelectric low-molecular liquid crystal includes, for example, one or more ferroelectric low-molecular liquid crystals, and a mixture of one or more ferroelectric low-molecular liquid crystals and other low-molecular liquid crystals. Ferroelectric low-molecular liquid crystals can be used. Examples of the ferroelectric polymer liquid crystal include, for example, one or more ferroelectric polymer liquid crystals, one or more ferroelectric low-molecular liquid crystals, and one or more ferroelectric polymers. Examples include a ferroelectric polymer liquid crystal composed of a liquid crystal, and a ferroelectric polymer liquid crystal composed of one or more ferroelectric low-molecular liquid crystals and one or more other polymer liquid crystals. That is, as the ferroelectric polymer liquid crystal, a ferroelectric polymer liquid crystal (a homopolymer or a copolymer or a mixture thereof), in which the polymer molecule itself exhibits ferroelectric liquid crystal properties, a ferroelectric polymer liquid crystal, and A mixture of a polymer liquid crystal and / or a normal polymer, a mixture of a ferroelectric polymer liquid crystal and a ferroelectric low-molecular liquid crystal, a ferroelectric polymer liquid crystal and a ferroelectric low-molecular liquid crystal and a polymer liquid crystal, and / or Polymer liquid crystals exhibiting all ferroelectricity, such as mixtures with ordinary polymers or mixtures of these with ordinary low-molecular liquid crystals, can be used. Among the ferroelectric polymer liquid crystals, for example, a side chain type ferroelectric polymer liquid crystal having a chiral smectic C phase is preferably used.

Examples of the ferroelectric liquid crystal compound include desyloxybenzylidene-P'-amino-2-methylbutylcinnamate (DOBAMBC) and hexyloxybenzylidene-P'-amino-2-chloropropylcinnamate (HOBACPC). And 4-o- (2-methyl)-
Butylresorcylidene-4'-octylaniline (MB
RA8) and the like. When a device is formed using these materials, the liquid crystal compound is formed of SmC * phase or SmH
* The element can be supported by a copper block or the like in which a heater is embedded, if necessary, for maintaining the temperature in a phase. In the present invention, the aforementioned SmC *, S
In addition to mH *, chiral smectic F phase, I phase, J phase,
It is also possible to use a ferroelectric liquid crystal that appears in the G phase or the K phase. In addition, the ferroelectric liquid crystal composition contains an adhesive, a viscosity reducing agent, a non-liquid crystal chiral compound, a dye, and the like, if necessary. The thickness of the liquid crystal layer is not particularly limited.
It is preferably set to μm.

The display side substrate 2 is made of a transparent polymer material such as polyethersulfone, polyarylate, aromatic polyester, polyetherimide, polyimide, polycarbonate, polyester, and epoxy resin. 0.2 to 5 mm, preferably 0.5 to 2 mm from the viewpoint of the viewing characteristics of the panel.

As the back substrate 3 opposite to the display side, a resin substrate made of a flexible film having a thickness of 0.2 mm or less is used. The resin substrate is not particularly limited as long as it is a flexible and transparent material. For example, a plastic film such as polyethylene terephthalate (PET), polyether sulfone (PES), and polycarbonate (PC) can be used. The thickness of the substrate may be 0.2 mm or less, preferably 10 μm
To 0.2 mm.

Electrodes (not shown) are provided on one surface of the substrates 2 and 3 on the liquid crystal material 1 side, but the electrodes are not particularly limited as long as they are transparent materials. For example, a transparent electrode such as an ITO film made of indium oxide or a mixture of indium oxide and tin oxide is suitable, and these are usually deposited on the above-mentioned flexible substrate.

FIG. 2 shows a second embodiment of the present invention in which the display-side substrate 2 is formed of a substrate having a high flexural rigidity. Epoxy, as a substrate material with high flexural rigidity (bending strength)
A transparent polymer material having a large flexural modulus such as polycarbonate, polyetherimide, polyimide, and polyacrylate is used. In this case, the bending strength of the substrate 2 is preferably 300 kgf / mm ² or more from the viewpoint that the amount of deformation of the substrate due to bending stress is small, and the thickness of the substrate 3 is 0.2 mm or less. Is preferred.

FIG. 3 shows one embodiment of the present invention in which a protective layer 4 made of a transparent elastic member is formed on the display side surface of the display side substrate 2. As the transparent elastic member forming the protective layer 4, a transparent sheet-like member made of silicon rubber or fluorine rubber is used. In this case, if the protective layer 4 is too thick, the transparency is reduced. When the protective layer 4 is formed, a flexible resin sheet having a thickness of 0.2 mm or less, similar to the back substrate 3, may be used as the display-side substrate 2.

FIG. 4 shows another embodiment of the present invention in which a shock absorbing layer 5 is formed between a support member 6 of a device case incorporating a ferroelectric liquid crystal display element. This embodiment is:
This is to prevent impact and pressure from being applied to the ferroelectric liquid crystal display element from the side of the device incorporating the ferroelectric liquid crystal display element. The impact absorbing layer 5 is not particularly limited, and an elastic member such as urethane foam or rubber can be used. In this case, a film-shaped substrate made of the above-mentioned flexible resin may be used as the back substrate 3 of the ferroelectric liquid crystal display element. On the other hand, the same substrate as the back substrate 3 can be used as the display substrate 2.

The display-side substrate 2 can be provided with an antiglare effect by preventing light reflection, depending on the use of the ferroelectric liquid crystal display element. For example, the surface of the substrate 2 may be roughened by sand blasting or the like to have fine undulations of about several μm, an antiglare-transparent film may be attached to the surface of the substrate 2, or fine glass beads may be used as a substrate material. To give the display-side substrate 2 an anti-glare effect. In this way, reflected light from lighting or the like can be prevented, and the display can be easily viewed. Reference Example 1 described above
Needless to say, such anti-glare processing can be performed on the display-side substrate 2 of the ferroelectric liquid crystal display element according to the first to second embodiments and the embodiments.

As described above, the ferroelectric liquid crystal display device of the present invention in which the liquid crystal material 1 and the substrates 2 and 3 are formed of resin not only has excellent impact resistance and the like, but also has the form of a ferroelectric liquid crystal display device. It can be changed in various ways, and the safety is improved by not using glass.

Next, a method for manufacturing a liquid crystal display device will be described. The liquid crystal material 1 is applied to the substrate by dissolving or heating the liquid crystal material with a solvent to increase the fluidity, and the liquid material is applied to the electrode-side surface of the substrate with electrodes by a microgravure method, a direct gravure method, or the like. A method of applying a uniform film thickness is suitable. In addition, a rock member is impregnated with a liquid crystal material having improved fluidity, and the impregnated member is pressed against the electrode-side surface of the electrode-equipped substrate and applied while being moved (described in JP-A-2-10322). Are also suitable. The application of the liquid crystal is usually performed on the back substrate 3 having flexibility.

Next, in the substrate overlapping step, another display side substrate 2 is overlapped on the formed liquid crystal layer 1 such that the liquid crystal layer 1 and the surface of the display side substrate 2 on the electrode side are in contact with each other. Match. Then, the substrate 2 to be superimposed and the liquid crystal layer 1
The upper and lower substrates 2 and 3 are overlapped so that air bubbles do not enter between them, and the liquid crystal layer 1 is sandwiched between the upper and lower substrates 2 and 3 with a uniform film thickness. At this time, it is preferable to heat the substrate 2 to be overlaid.

It is preferable that the liquid crystal material is subjected to an alignment treatment when sandwiched between substrates with electrodes or thereafter, so that the liquid crystal molecules of the liquid crystal composition are uniaxially horizontally aligned. The method of the alignment treatment is not particularly limited, and for example, a conventionally well-known rubbing method, oblique deposition method, magnetic field application method, temperature gradient method, or the like can be used. When a polymer liquid crystal composition is used, the superposed substrates are heated, and the upper and lower substrates are sheared and sheared at a temperature lower than the phase transition point between the isotropic phase and the liquid crystal phase to align the liquid crystal material. A method of aligning liquid crystal molecules (described in JP-A-2-10322) is preferred.

Next, in the ferroelectric liquid crystal display elements according to the reference examples 1 and 2 and the embodiment, the display side substrate 2 which is selected in advance according to the embodiment is used, and the display side substrate 2 and the back side substrate 3 are used. On the outside, a polarizing plate is disposed so as to be in a crossed Nicols state (not shown). At this time, the contrast when the electric field is applied is maximized. When the ferroelectric liquid crystal display element is of a guest-host type, one polarizing plate (not shown) is provided on the display side or the outside of the substrates 2 and 3 on the back side. Further, in order to provide an anti-glare effect to the ferroelectric liquid crystal display element, the surface of the display-side substrate 2 is subjected to anti-glare processing in advance. Thus, the ferroelectric liquid crystal display devices of Reference Examples 1 and 2 can be obtained,
In the case of manufacturing the ferroelectric liquid crystal display device of the embodiment, a protective layer 4 made of a transparent rubber sheet or the like is formed on the outside of the display-side substrate (polarizing plate) 2 or the back-side substrate (polarizing plate). The shock absorbing layer 5 made of an elastic member is formed between the outside of the support member 3 and the support member 6.

[0022]

EXAMPLES and REFERENCE EXAMPLES Reference Example 1 A 5.4 g pachinko ball was weighed on a display side substrate from a height of 1 m on a ferroelectric liquid crystal display element using a 1 mm thick resin substrate as the display side substrate. Let it fall naturally. Table 1 shows the orientation state at that time. Reference Example 2 A display-side substrate having a thickness of 0.2 mm and a bending strength of 350 kgf
/ Mm ² resin substrate with ferroelectric liquid crystal display element,
A pachinko ball was dropped under the same conditions as in Reference Example 1. Table 1 shows the orientation state at that time. Example 3 A pachinko ball was dropped under the same conditions as in Reference Example 1 on a ferroelectric liquid crystal display device in which a protective layer made of silicon gel having a thickness of 5 mm was formed on the display surface of a display-side substrate having a thickness of 0.2 mm. Was. Table 1 shows the orientation state at that time. Reference Example 4 A ferroelectric liquid crystal display element having a shock absorbing layer of 10 mm in thickness made of urethane foam formed between a back substrate having a thickness of 0.1 mm and a case (support member) of a liquid crystal display device has a weight of 5%. A 0.4 g pachinko ball was naturally dropped into the case from a height of 1 m. Table 1 shows the orientation state at that time. Comparative Example A pachinko ball was dropped under the same conditions as in Reference Example 1 on a ferroelectric liquid crystal display device in which a liquid crystal material was sandwiched between two substrates each having a thickness of 0.1 mm and not subjected to an impact treatment.
Table 1 shows the orientation state at this time.

[0023]

[Table 1] Panel orientation change ratio (%)  Reference Example 1 0 〃 20 Example 3 0 Reference Example 4 0 Comparative Example 40

As a result, it was found that the ferroelectric liquid crystal display elements of each of the examples and the reference examples did not suffer from deterioration of the alignment and had sufficient impact resistance.

[0025]

As described above, according to the ferroelectric liquid crystal display device of the present invention, excellent display quality can be obtained without deteriorating liquid crystal due to mechanical shock and the like, and excellent display quality can be obtained. However, the freedom of form can be maintained.

[Brief description of the drawings]

FIG. 1 is a partial sectional view of a ferroelectric liquid crystal display element according to a first embodiment of the present invention.

FIG. 2 is a partial sectional view of a ferroelectric liquid crystal display element according to a second embodiment of the present invention.

FIG. 3 is a partial sectional view of a ferroelectric liquid crystal display device according to a third embodiment of the present invention.

FIG. 4 is a partial cross-sectional view of a ferroelectric liquid crystal display device according to a fourth embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Ferroelectric liquid crystal material 2 ... Display side substrate 3 ... Backside substrate 4 ... Protective layer 5 ... Shock absorber

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-64-15717 (JP, A) JP-A-2-178625 (JP, A) JP-A-2-68521 (JP, A) JP-A-62 59922 (JP, A) JP-A-4-67013 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G02F 1/141 G02F 1/1333 500

Claims (3)

(57) [Claims] 1. A liquid crystal display device in which a ferroelectric liquid crystal is sandwiched between two transparent resin substrates having a transparent conductive film, wherein said two transparent resin substrates are formed of a flexible film substrate having a thickness of 0.2 mm or less. A ferroelectric liquid crystal display device, wherein a protective layer is formed on a display side surface of the display-side substrate with an elastic member having a thickness of 1 to 5 mm and made of silicon rubber or fluoro rubber having transparency. 2. The ferroelectric liquid crystal display device according to claim 1, wherein the protective layer is made of silicon gel. 3. The ferroelectric liquid crystal display device according to claim 1, wherein a shock absorbing layer is formed between the back substrate and the supporting member of the two transparent resin substrates.