JPH0467017A - liquid crystal display device - Google Patents

Abstract

PURPOSE:To obtain excellent display characteristics without the disorder of orientation, breakage, demounting, etc, even when a shock is applied by providing an elastic member which relaxes the deformation of a substrate due to an external shock at the periphery of the substrate. CONSTITUTION:Silicone gel or ether-based polyurethane is arranged as the elastic body which relieves a shock at the periphery of a liquid crystal element so as to protect the liquid crystal element against an external shock. The elastic member 19 is arranged and supported at four sides below an EL back light 13. Namely, even if an external shock is applied, the majority of the shock is absorbed by the elastic body, so the shock is not transmitted directly to the liquid crystal panel. Consequently, the excellent display characteristics are obtained without the disorder of orientation, glass breakage, demounting, etc., even after the external shock is applied. Consequently, the liquid crystal element which is reinforced against the external shock and tolerant to a shock is 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 various consumer and office automation displays such as pocket TVs and laptop computer displays, and are gradually replacing CRTs, which were conventionally used in displays. Currently, two-layer STN liquid crystals using nematic liquid crystals are currently on the market, but they have many problems in terms of response speed, two viewing angles, and display capacity. On the other hand, ferroelectric liquid crystals have excellent characteristics such as high-speed response and memory performance that are not found in Meimatic liquid crystals, and have a large display capacity.
Active research and development is underway as a next-generation high-quality display.

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 helical 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 are reversed by 26 around the layer normal Z. With these two states, bright and dark display can be performed using a polarizing plate.

FIG. 3(a) to FIG. 3(C) are diagrams of the operating principle of a ferroelectric liquid crystal. Fig. 3(a) shows the state where no voltage is 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, 6 is a liquid crystal molecule whose long axis of the molecule is tilted by 10 with respect to the layer normal, and 7 is a dipole facing toward the surface of the paper. moment,
8 is the dipole moment facing the back of the page, 9 is 2
This is the direction of the polarizing plates.

When a ferroelectric liquid crystal is sandwiched between glass substrates with transparent electrodes and its thickness is made less than a spiral pinch, when no voltage is applied, the spiral unravels as shown in Fig. 3(a), and the layer is twisted. It is divided into a region of 0 tilted liquid crystal molecules 5 and a region of 10 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(b). Furthermore, when a voltage is applied in the opposite direction to the above, the entire cell becomes a monodomain extending 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 structure of a conventional liquid crystal display element is shown in FIG.

As shown in FIG. 11, 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. In this way, conventional liquid crystal display devices
The structure was not designed to absorb shocks applied from the outside, and the shocks directly led to deformation of the board.

There have also been examples of using shock absorbing members, but they have been made of butyl rubber, silicone rubber, etc., and have not been designed to absorb shock very effectively.

Problems to be Solved by the Invention Display devices using smectic liquid crystals, which have a layered structure among liquid crystals, cannot display images because the layered structure is easily destroyed by external shocks. Moreover, once the alignment state of the liquid crystal is disrupted by an external impact, there is a serious problem in that 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 packaging due to impact, and they have the problem of being vulnerable to impact.

The present invention is intended to solve these problems, and an object of the present invention is to provide a liquid crystal baffle that can obtain good display characteristics without causing any disturbance in orientation, damage, or dismounting even when an external impact is applied. That is.

Means for Solving the Problems In order to achieve this object, the present invention provides silicone gel or ether-based polyurethane, which is placed around the liquid crystal element as an elastic body that cushions the impact, in order to protect the liquid crystal element from external impact. This is what I did.

Effect 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. As a result, even after application of an external shock, good display characteristics can be obtained without causing disorder in alignment, glass breakage, or mounting failure.

EXAMPLE Hereinafter, a liquid crystal display device according to an example of the present invention will be explained with reference to the drawings. FIG. 1 shows an example of the configuration of a liquid crystal display device according to the present invention. As shown in 2, 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 I2.
A polarizing plate 11 or a reflecting plate 11 is provided on the lower surface, and an EL light source 13 is arranged below it with a connector 14 and a support frame 15. The support stand 18 is made of acrylic resin and has a thickness of 2 mm. Incidentally, the same members as those in FIG. 11 showing the conventional example are given the same numbers and explanations thereof will be omitted.

Further, the present invention is not limited to this FL-type liquid crystal display device. 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
Technical Report, 33N0
．． 1 Pd21987). Furthermore, taking flicker into consideration, the pulse width of the 7) pulse was set to be the same as that of the selection pulse.

An organic alignment layer (not shown) was applied to the upper and lower glass substrates 12 with transparent electrodes (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 applied to 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 in G below were used.

(]) Noricone Gel 5E-1890 manufactured by Toray Dow Corning Silicone Co., Ltd. (2) Sorbothane manufactured by Nishin Kosan Co., Ltd. The S type elastic member 19 was placed under the EL backlight 13 so as to be supported on four sides. conduct a test,
The impact applied to the panel was measured. As shown in Figure 11, in the case of a conventional structure that does not include an elastic member, the orientation is disturbed by a fall from a height of 1.0CI, resulting in a needle texture as shown in Figure 9, making matrix drive impossible. Ta.

Further, the impact acceleration at that time was 30G.

As the height of the fall is further increased, the orientation becomes the sump as shown in Figure 10 after falling from a height of 3c16.

Changed to DoText. The impact acceleration at this time is 10
It was 0G. Next, similar experiments were conducted on the ferroelectric liquid crystal element of the present invention. First, when the silicone gel (1) was used, there was no distribution disorder at all when falling from 1.0C11, and the impact acceleration was 4G.

When dropped from a height of 3 cm, there was no orientation disturbance at all, and the impact acceleration was 15 G. When falling from 81, the needle texture appeared and the display looked like Nozomi Fuji. The impact acceleration at this time was 30G. Next, when using sorbothane, 1. There was no orientation disturbance when falling from Qcm. In this case, the impact acceleration was 15G. In the drop test from 3 cm, needle texture occurred and it became impossible to display. The impact acceleration at this time is 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).

The thickness of each elastic member must be at least 2 mm!
Relaxation performance was recognized. Further, in this example, only the four sides of the lower part were supported, but impact mitigation performance was observed even when supported on two sides or on the entire surface.

Other configurations are shown in FIGS. 4 to 8. FIG. 4 shows an example in which a shock absorbing material is arranged on the front surface of the panel. This structure makes the panel more resistant to impacts from the front. FIG. 5 shows an example in which impact cushioning material is arranged not only on the back side of the panel but also on the front side. With this arrangement, it is strengthened not only against impacts from the back but also from the front. FIG. 6 shows an example in which a shock absorber is placed on the back side of the panel. This arrangement strengthens the structure against impacts from the back.

FIG. 7 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. By combining the structure shown in FIG. 7 with the structures shown in FIGS. 1 and 4 to 6, 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.

Furthermore, the arrangement of the elastic members is not limited to these examples, but may be any arrangement that can alleviate external impact. FIG. 8 shows a structure when a fluorescent lamp is used as a backlight. 2
0 is a bank light 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 6 in which the EL butterfly light section is replaced with a fluorescent lamp light source.

Composite structures of each are also possible. In all of these structures, those using silicone gel are 8 times more
The impact resistance was more than doubled by using sorposeine.

A similar test was conducted using a similar structure for a device using nematic liquid crystal, but although there was no change in orientation, the drop height that caused glass breakage and peeling of the mounting side was higher than that of the conventional structure using silicone gel. The increase was more than 8 times, and the increase was more than 2 times when Sorbothane was used.

In addition, compared to silicone rubber butyl rubber, which has been conventionally used as an elastic member, Sorposein is 1.5 times more effective and silicone gel is 6 times more effective.
Noricone gel has been confirmed to be more than twice as strong.
Ether-based polyurethane is the town! As an elastic member for the purpose of mitigation, it exhibits impact mitigation performance even in a very thin shape.
It turned out to be particularly good.

Effects of the Invention As is clear from the description of the embodiments above, according to the present invention, silicone gel or ether-based polyurethane is placed on the liquid crystal element as a shock absorbing material to reduce external shock. A liquid crystal display element that is reinforced and resistant to impact can be provided.

[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 the display mode of a ferroelectric liquid crystal, Figures 4 to 8 are cross-sectional views of a liquid crystal display device with another structure of the present invention, and Figures 9 and 10 show how the alignment of liquid crystals due to impact is disturbed. The figure shown in FIG. 11 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,
19...Elastic member, 20...Fluorescent lamp backlight unit. Name of agent Patent attorney Shigetaka Awano 1 person 10--1 false destination ↓ and 11-1 1n11 and analysis 12--j ras group 1i 1 to moxibustion v1 roux 4 1C・-1! IF visit qco

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 orientation treatment, and which includes an elastic member to reduce deformation of the substrate due to external impact. A liquid crystal display device installed around the board. (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.