JPH0467013A - liquid crystal display device - Google Patents

Abstract

PURPOSE:To eliminate the influence of a liquid crystal display function even when an external shock or stress is applied to a liquid crystal panel by using silicone gel or ether-based polyurethane as an elastic body which relaxes the external shock and providing a protection cover. CONSTITUTION:The protection cover 20 is fixed on a polarizing plate 10 across an elastic member 19 by a support frame. In this case, even if an external shock is applied to a liquid crystal element, the majority of the shock is absorbed by the elastic body, so the shock is not transmitted directly to a liquid crystal panel. Further, the protection cover 20 is provided even for external stress application, so no external force is transmitted directly to the liquid crystal panel and the device is reinforced for the external stress. Consequently, excellent display characteristics are obtained.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a liquid crystal display device.

BACKGROUND OF THE INVENTION In recent years, liquid crystal displays have come to be used in a variety of consumer and office automation displays such as blurry TVs and lamp-top computer displays, and are gradually replacing CRTs, which were conventionally used in displays. Currently, two-layer STN liquid crystals using nematic liquid crystals are the mainstream on the market, but they have many problems in terms of response speed, two viewing angles, and display capacity. Ferroelectric liquid crystals, on the other hand, have excellent characteristics such as high-speed response and memory performance that nematic liquid crystals do not have, and are being actively researched and developed as next-generation displays with large display capacity and high quality. There is.

Figure 2 shows a schematic diagram of a ferroelectric liquid crystal. The ferroelectric liquid crystal 1 is a liquid crystal having a layer structure 4, which is usually called a smectic liquid crystal, and the liquid crystal molecules have a structure tilted by an inclination angle θ with respect to the layer direction Z.

As shown in Figure 2, ferroelectric liquid crystal molecules can move freely on a cone 3 (conical shape) tilted θ with respect to the layer normal direction, and the long axis direction of the molecules differs from layer to layer. and
The structure as a whole has a twisted structure.

Furthermore, ferroelectric liquid crystal molecules are composed of optically active liquid crystal molecules that are not racemic, and have spontaneous polarization 3 in a direction perpendicular to the long axis of the molecule. Therefore, depending on the direction in which the electric field is applied, the molecules undergo a 2θ inversion with the layer normal Z as an axis, and these two states can be used to display brightness and darkness using a polarizing plate.

FIG. 3(a) to FIG. 3(C) are diagrams of the operating principle of a ferroelectric liquid crystal. Figure 3(a) shows the state with no voltage applied;
FIG. 3(b) is a diagram showing the principle of operation when a voltage is applied from the back to the front of the paper, and FIG. 3(C) is a diagram showing the principle of operation when a voltage is applied in the opposite direction. 5 is a liquid crystal molecule whose long axis of the molecule is tilted by +θ with respect to the layer normal Z, 6 is a liquid crystal molecule whose long axis of the molecule is tilted by 10 degrees with respect to the layer normal, and 7 is a dipole facing toward the surface of the paper. The child moment, 8 is the dipole moment facing toward the back of the paper, and 9 is the direction of the two polarizing plates.

When a ferroelectric liquid crystal is sandwiched between glass substrates with transparent electrodes and the thickness is made less than the helical pitch, when no voltage is applied, the helix unravels as shown in Figure 3(a), and the layer is It is divided into a region of tilted liquid crystal molecules 5 and a region of -θ tilted liquid crystal molecules 6. By applying a voltage between the upper and lower electrodes from the back to the front of the paper, the entire cell becomes a monodomain tilted by +θ as shown in FIG. 3 [1)). Furthermore, when a voltage is applied in the opposite direction to the above, the entire cell becomes a monodomain tilted by 1θ, as shown in FIG. 3(C).

Therefore, if birefringence or dichroism is utilized due to the electro-optic effect, brightness and darkness can be represented by two states extended by +-θ.

The configuration of a conventional ferroelectric liquid crystal display element is shown in FIG.
As shown in FIG. 12, liquid crystal is filled between the upper and lower glass substrates 12, and a polarizing plate 10 is placed on the top surface of the glass substrate 12, and a polarizing plate 11 is placed on the bottom surface of the glass substrate 12 in the case of a transmissive type, and the polarizing plate 11 in the case of a reflective type. A reflector 11 is provided, and an EL backlight 13 is provided below it.
are arranged by the connector 14 and the support frame 15.

Further, the circuit board 16 is fixed to a support stand 18 with screws 17. As described above, conventional ferroelectric liquid crystal display devices are not configured to absorb shocks applied from the outside, and the shocks directly lead to deformation of the substrate. There were also examples of using impact members, but they were made of butyl rubber, noricone rubber, etc., and were not designed to absorb impact very effectively.

Problems to be Solved by the Invention Display devices using smectic liquid crystals, which have a layered structure among liquid crystals, are unable to display because the layered structure of the liquid crystal easily collapses due to the application of stress from external shocks and external forces. . Furthermore, there is a serious problem in that once the alignment state of the ferroelectric liquid crystal is disrupted by the application of stress from an external impact or external force, it cannot be recovered unless the temperature is raised to a temperature higher than the nematic phase. On the other hand, display devices using nematic liquid crystals do not have such serious problems, but they do suffer from problems such as glass breakage and peeling of the mounting due to impact, and they have a common problem of being vulnerable to impact and stress. was.

The present invention solves these problems, and aims to provide a liquid crystal display device whose liquid crystal display function is not affected even if shock or stress is applied to the liquid crystal panel from the outside.

Means for Solving the Problems In order to achieve the above object, the present invention uses silicone gel or ether-based polyurethane as an elastic body to relieve external stress in order to protect the liquid crystal element from external impact. A protective cover is provided for this purpose.

Operation With this configuration, even if an external impact is applied to the liquid crystal element of the present invention, most of it is absorbed by the elastic body, so that the impact is not directly transmitted to the liquid crystal panel. Furthermore, since a protective cover is provided to prevent external stress from being applied, external force is not directly transmitted to the liquid crystal panel, and the liquid crystal panel is strengthened against external stress.

As a result, even after external impact or external stress is applied, good display characteristics can be obtained without causing disorder in the alignment of the liquid crystal, glass breakage, or dislodgement of the penetration.

Example Below is a liquid crystal display word of an example of the present invention! will be explained using drawings. FIG. 1 shows an example of the configuration of a liquid crystal display device according to the present invention. As shown in the figure, liquid crystal is filled between the upper and lower glass substrates 12, and a polarizing plate 10 is placed on the upper surface of the glass substrate 12.
A polarizing plate 11 or a reflecting plate 11 is provided on the lower surface, and an EL backlight 13 is arranged below it with a connector 14 and a support frame 15. Furthermore, a protective cover 20 is fixed onto the polarizing plate 10 via an elastic member 19 by a support frame. The support stand 18 is made of acrylic resin and has a thickness of 2 mm. Incidentally, the same members as those in FIG. 12 showing the conventional example are given the same numbers and explanations thereof will be omitted.

Further, the present invention is not limited to a liquid crystal display device having this structure. The module may have any configuration, support method, etc. In the following examples, the matrix waveform used in the matrix drive test measurement was the waveform of the 4-pulse method proposed by Wakita et al. (National T
electrical report vol, 33Nct
lPd21987). Furthermore, taking flicker into consideration, the pulse width of the reset pulse was made the same as that of the selection pulse.

An organic alignment film was coated on the upper and lower glass substrates 12 of the transparent electrode material (not shown), and after curing, the surfaces were subjected to a rubbing treatment to create a rubbing cell with a thickness of 2 μm. A ferroelectric liquid crystal composition was injected into this cell to create a ferroelectric liquid crystal panel.

Using this ferroelectric liquid crystal panel, a ferroelectric liquid crystal display element as shown in FIG. 1 was fabricated. Two types of elastic members 19 shown below were used.

(1) Noricone Gel 5E-1890 manufactured by Toray Dow Corning Silicone Co., Ltd. (2) Sorbothane S type manufactured by Ohdo Kosan Co., Ltd. Also, the protective cover 20 placed on the front of the panel is an acrylic resin plate or glass plate with a thickness of 2 mm or more. there was. The elastic member 19 is arranged to support the periphery of the protective cover 20 on four sides. With this configuration, a panel drop test was conducted to measure the impact that caused the panel to break. As shown in Figure 12, in the case of a conventional structure that does not include an elastic member, a fall from a height of 1.0 C11 disrupts the orientation, resulting in a needle texture as shown in Figure 10, making matrix drive impossible. became. Further, the impact acceleration at that time was 30G. As the height is further increased, the orientation changes to a sanded texture as shown in FIG. 11 due to a fall from the height of 3C11.

The impact acceleration at this time was 100G. Next, similar experiments were conducted on the ferroelectric liquid crystal element of the present invention. First, when silicone gel (No. 11) was used, there was no alignment film tearing at all when dropped from 1.0 cm, and the impact acceleration was 4G.

When dropped from a height of 3 cm, there was no alignment film tearing at all, and the impact acceleration was 15 (. Next, when sorbothane was used, there was no alignment film tearing when dropping from 1.0C11.Also, in this case, the impact acceleration was 15G.When dropping from 31, the needle texture was displayed. It became impossible.The impact acceleration at this time was 50
It was G.

As described above, it can be seen that by using the elastic member, the strength against impact is increased by 8 times in the case of silicone gel (1) and 2 times in the case of sorbothane in (2).

Impact-reducing performance was observed when the thickness of each elastic member was 2 mm or more. In addition, in the configuration of this example, only the four sides of the upper part were supported, but impact mitigation performance was observed even when supported on two sides or on the entire surface.

Next, we examined the effect of applying external force. In the conventional state without a protective cover as shown in Figure 12, distribution disturbances occurred simply by applying a static load of approximately 300 g to the center of the panel, but with the configuration as shown in Figure 1 with a protective cover. , no orientation disturbance occurred up to a load of I kg.

By configuring the protective cover and the shock absorbing material in this way, the protective cover is strengthened against external impact and external force.

Other configurations are shown in FIGS. 4 to 9. Figure 4 shows an example in which an impact material is placed between the protective cover and the panel. With this configuration, it is further strengthened against the application of external force. Figure 5 shows not only the back of the panel but also the This is an example in which the shock absorbing material is placed on the front of the protective cover.This arrangement strengthens the impact not only from the back but also from the front.Figure 6 shows the structure of the protective cover and panel. This is a case where shock absorbing material is placed between the panels and on the back of the panel. With this structure, it is strengthened against impact and external force applied from the front and back of the panel. Figure 7 shows a case where shock absorbing material is placed on the back side of the panel. This is an example of arranging.

This arrangement strengthens the structure against impacts from the back. FIG. 8 shows an example in which a shock absorbing material is placed on the back side of the circuit board. With this structure, the deflection of the circuit board when receiving an impact from the back side can be alleviated, so that the impact can be effectively absorbed. In addition,
By combining this structure and the structures shown in FIGS. 1 to 7 in a complex manner, it is possible to significantly strengthen the structure against impact.

Further, although these structures employ a method of fixing to a circuit board, the structure is not limited to this structure, and if the mounting form changes (for example, TAB method or COG method), the structure will be different.

Further, the arrangement of the elastic members is not limited to these examples, and may be arranged as long as it alleviates external impact. FIG. 9 shows a structure when a fluorescent lamp is used as a backlight. 2
1 is a Hanokrite unit. In the case of using a fluorescent lamp, it is of course possible to use the structure shown in FIGS. 1 and 4 to 9 in which the EL backlight section is replaced with a fluorescent lamp light source.

Further, a composite structure of FIG. 9, FIG. 1, and FIGS. 4 to 9 is also possible. In all of these structures, the impact resistance was enhanced by more than 8 times in those using silicone gel, and by more than 2 times in those using sorposein.

A similar test was conducted with a similar structure using a nematic liquid crystal, but no change in orientation occurred, but
Compared to conventional structures, the fall impact that causes glass breakage and mounting peeling is more than 8 times greater with silicone gel structures.
It more than doubled when Sorbothane was used.

In addition, compared to elastomers such as noricone rubber and butyl rubber, which are conventionally used as elastic members,
When comparing similar structures, it has been confirmed that Sorbothane is 1.5 times stronger and Soricone gel is more than 6 times stronger. Silicone gel and ether-based polyurethane can be used as elastic members for the purpose of impact mitigation in a very thin shape. It was found that it exhibited particularly excellent relaxation performance.

Effects of the Invention As is clear from the description of the embodiments, according to the present invention, a liquid crystal element is provided with a shock absorbing material such as Noricone gel or ether-based polyurethane to alleviate external forces, and a protective cover to further alleviate external forces. This arrangement makes it possible to provide a liquid crystal display element that is strengthened against external impact and force, and is resistant to impact and external stress.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a liquid crystal display device according to an embodiment of the present invention, FIG. 2 is a perspective view showing the principle of orientation of ferroelectric liquid crystal molecules, and FIG.
The figure shows a display mode of a ferroelectric liquid crystal, Figures 4 to 9 are cross-sectional views of a liquid crystal display device having another structure according to the present invention, and Figures 10 and 11 show disordered alignment of liquid crystal due to impact. FIG. 12 is a sectional view of a conventional liquid crystal display device. 10...Polarizing plate, 11...Polarizing plate or reflecting plate, 12...Glass substrate, 13...
・Backlight, 14... Connector, 15...
...Support frame, 16...Circuit board, 1
9...Elastic member, 20...Protective cover, 2
1...Fluorescent backlight unit. Agent's name Patent attorney Shigetaka Awano Written by 1 Figure Io-iNo1 5) En-A4txsr=+tn#K If-1'Usu base 5 +3---1\゛・Recla 7 ni +4--- ]Netsuri+5-m-Support Room+g---N 1WL Suq-41 Miri [nl se11'l posted

Claims (11)

[Claims] (1) A liquid crystal display device that has a voltage application means and a liquid crystal layer sandwiched between two substrates whose surfaces have been subjected to alignment treatment, and the substrates are surrounded by a structure that prevents deformation of the substrate due to external impact. A liquid crystal display device equipped with an elastic member that relieves external forces and a protective cover on the front of the panel that relieves external forces. (2) Claim 1 in which silicone gel is used as the elastic member.
The liquid crystal display device described. (3) The liquid crystal display device according to claim 1, wherein ether polyurethane is used as the elastic member. (4) The liquid crystal display device according to any one of claims 1 to 3, wherein the elastic member has a thickness of 2 mm to 40 mm. (5) The liquid crystal display device according to any one of claims 1 to 3, wherein the elastic member is disposed at least on the back surface of the panel. (6) The liquid crystal display device according to any one of claims 1 to 3, wherein the elastic member is disposed between the panel and the protective cover. (7) The liquid crystal display device according to any one of claims 1 to 3, wherein the elastic member is arranged between the panel and the protective cover and on the back surface of the panel. (8) The liquid crystal display device according to any one of claims 1 to 7, wherein the alignment treatment of the liquid crystal is performed by rubbing an organic film. (9) The liquid crystal display device according to any one of claims 1 to 8, wherein the alignment treatment of the liquid crystal is performed by oblique evaporation of SiO. (10) The liquid crystal display device according to any one of claims 1 to 9, wherein the liquid crystal layer is a smectic liquid crystal having a layered structure. (11) The liquid crystal display device according to any one of claims 1 to 10, wherein the liquid crystal layer is a liquid crystal exhibiting a chiral smectic C phase.