JPH09146078A - Liquid crystal element, manufacture of liquid crystal element, and liquid crystal device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the quantity of deflection when a shock is applied, reduce the shift in the surface direction between both substrates, and reduce the force acting on an adhesive, etc. SOLUTION: When a shock load is placed on the liquid crystal device 30, the upper and lower substrates 31a and 31b deflect. Here, since the upper substrate 31a is formed thicker than the lower substrate 31b, the deflection quantity is less than before when the overall thickness of both the substrates 31a and 31b is the same as before. Consequently, deterioration in picture quality and the generation of an orientation defect can be suppressed. Further, the shift in the surface direction between the reverse surface of the upper substrate 31a and the top surface of the lower substrate 31b is less than before. The layer structure of liquid crystal 21 can be prevented from being disordered and a picture quality defect and picture quality deterioration can be prevented. Since the upper substrate 31a is formed thicker than the lower substrate 31b, the lower substrate 31b is formed thinner than before on condition that, for example, the overall thickness of both the substrates 31a and 31b is the same as before, and consequently the force operating on the adhesive 11 is reduced to hold a cell gap uniform.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generally relates to a liquid crystal element for displaying various information by using liquid crystal and a liquid crystal device using the same.

[0002]

2. Description of the Related Art Conventionally, as a liquid crystal device for displaying various information using liquid crystal, an active matrix type device in which a transistor is arranged in each pixel as represented by a TFT liquid crystal, or no transistor is used. There is a simple matrix type, both of which are used in various fields. 1 and 2 show an example thereof.

As shown in FIG. 1, the liquid crystal device 1 is provided with a cell fixing plate (supporting member) 2 having an opening 2a formed therein. The cell fixing plate 2 has an adhesive 3 such as a silicone resin.
The liquid crystal element P ₁ is supported via the.

As shown in detail in FIG. 2, the liquid crystal element P ₁ is provided with a pair of upper and lower electrode substrates 5a and 5b arranged in parallel, and these electrode substrates 5a and 5b are the first and the first electrode substrates. And transparent substrates 6a and 6b as the second substrate (hereinafter, the upper glass substrate 6a is referred to as "upper substrate 6").
a "and the lower glass substrate 6b is referred to as a" lower substrate 6b ". These substrates 6a and 6b are made of the same glass material and set to the same plate thickness (for example, 1.0 mm thickness). A large number of stripe-shaped transparent electrodes 7a, ..., 7b, ... Are formed on the surfaces of the upper and lower substrates 6a, 6b, and these transparent electrodes 7a ,.
.. are arranged in a matrix to form a large number of pixels. The transparent electrodes 7a, ..., 7b, ... Are connected to a peripheral circuit (not shown) so that an appropriate voltage is applied. The transparent electrodes 7a, ..., 7b, ... Are covered with insulating films 9a, 9b.

On the other hand, spacers 10, ... Are arranged between the electrode substrates 5a, 5b so that the substrate gap is constant. Further, a large number of fine particle-shaped inter-substrate adhesives 11, ... Are arranged in this substrate gap, and both electrode substrates 5a, 5b are adhesively fixed. Furthermore, this substrate gap (hereinafter referred to as "cell gap")
Is closed by the sealing material 15 arranged at the edge thereof (see FIG. 3), and the ferroelectric liquid crystal 12 is injected into the gap. On the other hand, polarizing plates 13a and 13b are attached to the outer surfaces of the upper and lower substrates 5a and 5b, respectively.

In some cases, a backlight device is arranged below the liquid crystal element P _{1. In} that case, as shown in FIG. 4, the backlight device is provided between the chassis 16 and the cell fixing plate 2. A liquid crystal element P ₁ is arranged so as to be sandwiched. In the figure, reference numeral 17 is an elastic member.

In such a liquid crystal device, it is important to prevent external impacts and vibrations from being transmitted to the liquid crystal element P ₁ during transportation and use, and to prevent the liquid crystal element P ₁ from being deformed. A method in which a space adjacent to the liquid crystal element P ₁ is a substantially closed space and the deformation of the liquid crystal element P ₁ is suppressed by the air damper effect of the space is proposed in Japanese Patent Publication No. 6-36132.

When a voltage is applied to each of the transparent electrodes 7a, ..., 7b, ... From the peripheral circuits described above, the liquid crystal 12 of each pixel is switched, and a pixel through which light passes and a pixel through which light does not pass. It is configured to display various images in combination.

[0009]

By the way, the above-mentioned liquid crystal element P ₁ is deformed as shown in FIG. 3 due to various forces caused by shock or vibration during transportation or during use of the apparatus, resulting in poor image quality or deterioration of image quality. There was a problem that is caused. And
One of the problems in the case where the liquid crystal element P ₁ is deformed in this way is that a plane deviation occurs between the lower surface of the upper substrate 6a and the upper surface of the lower substrate 6b, which destroys the layer structure of the liquid crystal 12. There was a problem. The deviation will be described below.

Now, when there is no adhesive between the substrates, the substrate 6
When a and 6b bend as shown in the figure, the upper side expands and the lower side contracts with the neutral planes A and A as boundaries. The amount of expansion and contraction is
The larger the distance from the neutral planes A, A, the larger the substrate 6a, 6
It becomes maximum on the upper and lower surfaces of b. The illustrated arrow B,
As shown in C, the lower surface of the upper substrate 6a extends and the lower substrate 6b
The upper surface of the shrinks and there is a gap between the two surfaces. Temporarily, substrate 6
When the support span of a and 6b is 300 mm and the maximum deflection is 2 mm, the amount of expansion of the lower surface of the upper substrate 6a and the amount of contraction of the upper surface of the lower substrate 6b are about 30 μm, resulting in a deviation of about 60 μm in total. .

Further, the lower substrate 6b tries to move in the direction indicated by the arrow D in the drawing, but since it is attached to the upper substrate 6a via the inter-substrate adhesive 11 or the like, the lower substrate 6b A tensile force acts between the substrate 6b and the inter-substrate adhesive 11, between the substrate adhesive 11, and between the inter-substrate adhesive 11 and the upper substrate 6a. Therefore, the adhesive 1
1 may be peeled from the upper and lower substrates 6a and 6b, or the adhesive 11 may be stretched to increase the cell gap amount. Then, when the cell gap amount changes, the alignment state of the liquid crystal 12 is disturbed, and there is a portion where the liquid crystal 12 is not switched, which causes a problem of deterioration of image quality and defects.

Particularly, in the liquid crystal element using the ferroelectric liquid crystal, the cell gap amount is about 1 μm, and the STN and T
It is considerably thinner than FT liquid crystal. Therefore, it is very important to control the accuracy of the cell gap amount, and as described above, even if the cell gap is slightly changed by the impact or the like, the image quality is easily deteriorated. There is also a problem that the disordered alignment state cannot be easily restored.

Further, since the upper substrate 6a is coupled (supported) to the cell fixing plate 2, when the upper substrate 6a and the lower substrate 6b try to separate from or approach each other, the lower substrate 6b is liable to move by its own weight. The generated force acts on the inter-substrate adhesive 11 and the like. Assuming that the weight of the lower substrate 6b is 500 g,
If the impact acceleration of G acts, the inter-substrate adhesive 11
A tensile force (or compressive force) of 25 kgf will be applied to the above.

As a method for solving such a problem, there is a method of increasing the dispersion density of the adhesive agent 11. However, if the density is made higher than a predetermined value, the image quality deteriorates, which is not preferable. was there.

Therefore, the present invention provides a liquid crystal element that reduces the amount of deformation of the liquid crystal element when an impact load is applied to prevent deterioration of image quality and the occurrence of alignment defects, and a liquid crystal device using the same. It is intended.

[0016]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and is a transparent first arrangement arranged in parallel.
And a second substrate, and a liquid crystal element sandwiching the liquid crystal between these substrates, and driving the liquid crystal by a peripheral drive circuit to display an image, wherein the first substrate and the second substrate are provided.
It is characterized in that the board thicknesses of the substrates are different. In this case, the first substrate and the second substrate may be formed of the same material. Further, both the first substrate and the second substrate may be made of glass.

On the other hand, the second substrate is thinner than the first substrate, the first substrate and the second substrate are made of different materials, and the second substrate is the first substrate. 1
It may be lighter than the substrate. In this case, the first substrate is made of glass, and the second substrate
The substrate may be made of a resin lighter than the first substrate.

Further, a fine particle adhesive may be dispersed between the first and second substrates to bond the two substrates together. Further, the liquid crystal may be a ferroelectric liquid crystal.

On the other hand, the present invention is a method for manufacturing a liquid crystal element having a constant total thickness, which is formed by sandwiching liquid crystal between a pair of substrates, wherein substrates having different thicknesses are used as the pair of substrates. , Is characterized.

On the other hand, a liquid crystal device according to the present invention comprises any one of the above-mentioned liquid crystal elements and a supporting member for supporting the liquid crystal elements, and has a plate thickness of the first or second substrate. A thick substrate is supported by the support member.

Based on the above configuration, when an external force in a predetermined direction acts on the liquid crystal device, the liquid crystal element bends. Here, since the thickness of the first substrate and the thickness of the second substrate are different without changing the thickness of the liquid crystal element, the weight of the liquid crystal element itself does not change, and the same G value as when dropped is obtained. When it is applied to the liquid crystal element, the amount of bending becomes smaller than in the conventional case. Further, when the thicker one is used as the first substrate and the first substrate is supported by the supporting member, the adhesive disposed between the substrates has a tensile force corresponding to the weight of the second substrate. Thus, a peeling force corresponding to the weight of the second substrate acts between the adhesive and the substrate.
However, since the second substrate is formed thinner than the first substrate and the total thickness of the liquid crystal element is not changed, the self-weight of the second substrate becomes smaller than the conventional one, and as a result, the adhesion The force acting on the agent or the like becomes smaller than before. Further, when an external force in a predetermined direction acts on the liquid crystal device, the first
The first substrate and the second substrate are bent, and the inner surfaces of both substrates are displaced in the surface direction. However, since the plate thicknesses of the first substrate and the second substrate are different, The bending can be made smaller than that of the conventional one, and the amount of the deviation is reduced.

[0022]

Embodiments of the present invention will be described below with reference to the drawings. The same parts as those shown in FIGS. 1 and 2 are designated by the same reference numerals and the description thereof will be omitted.

First, a first embodiment of the present invention will be described with reference to FIG.

The liquid crystal device 30 according to this embodiment has the liquid crystal element P _2, the liquid crystal element P _2, as in the above conventional example, a pair of glass substrates 31a arranged in parallel,
31b (hereinafter, the upper glass substrate 31a is referred to as “upper substrate 31
a "and the lower glass substrate 31b is referred to as a" lower substrate 31b ". In the present embodiment, the upper substrate (first substrate) 31a is replaced with the lower substrate 31b (second substrate). ), Specifically, the upper substrate 31.
The thickness of a is 1.5 times (1.5 mm) that of the conventional type (about 1.0 mm), and the thickness of the lower substrate 31b is 0.5 mm compared to the conventional type (about 1.0 mm). Is thin. Therefore, the thickness of the liquid crystal element P ₂ according to the present embodiment is
It is the same as the thickness of the liquid crystal element P ₁ shown in the conventional example.

The cell fixing plate 2, the spacer 10, the inter-substrate adhesive 11, the encapsulating material 15, the ferroelectric liquid crystal 12, the polarizing plates 13a and 13b, etc. are the same as the conventional ones. That is, the upper substrate 31 a is bonded to the cell fixing plate 2 via the adhesive 3. In addition, the upper and lower substrates 31
Striped transparent electrodes, an insulating film, and the like are formed on the surfaces of a and 31b (not shown). Then, these transparent electrodes are connected to a peripheral circuit (not shown), and a voltage is appropriately applied. Furthermore, both substrates 31
Spacers 10, ... And inter-substrate adhesive 11, ... Are placed in the gaps a, 31b, and both substrates 31a, 31b are bonded so as to have a predetermined gap. Further, the cell gap is closed by a sealing material 15 arranged at the edge thereof, and the liquid crystal 12 is injected into the cell gap. Further, polarizing plates 13a and 13b are attached to the outer surfaces of the upper and lower substrates 31a and 31b, respectively.

When manufacturing this liquid crystal element P ₂ , transparent electrodes in stripes, insulating films, etc. are formed on the surfaces of upper and lower substrates 31a, 31b having different plate thicknesses, and these substrates 31a, 31b are attached. In addition, the liquid crystal 12 is further injected into the gap between the substrates to sandwich the liquid crystal 12 between the substrates. Thereby, the liquid crystal element P ₂ having a constant total thickness is manufactured.

Next, the operation of this embodiment will be described.

When an impact load acts on the liquid crystal device 30 in the downward direction, the upper and lower substrates 31a and 31b are bent as shown in FIG. 3, but the amount of the bending is smaller than that of the conventional one.

Here, the reason why the amount of flexure of the upper and lower substrates 31a and 31b becomes small will be described by a calculation formula.

Generally, the maximum bending amount δ of a rectangular member whose four sides are supported is given by the following equation.

[0031]

(Equation 1) δ = αWa ⁴ / Et ³ where α: side length ratio coefficient, W: load, E: Young's modulus,
a: side length, t: plate thickness Now, when the present invention and the conventional example are compared, since the shape and material of the glass substrate do not change, αa ⁴ / E becomes a constant, and if this is K, the glass is The maximum deflection amount δ of the substrate is
From the above formula,

[0032]

(Equation 2) (Equation 2) δ = KW / t ³ .

Since the total thickness of the liquid crystal element does not change,
The weight is the same, and the load W with respect to the G value applied to the liquid crystal element due to a certain impact is also the same, so that W can be treated as a constant.

Based on the equation 2, assuming that the deformation amounts of the two substrates when the two substrates are superposed are the same, if the plate thicknesses of the respective substrates are t ₁ and t ₂ , the maximum deflection is Quantity δ
Is

[0035]

[Formula 3] (Formula 3) δ = KW / (t ₁ ³ + t ₂ ³ )

Here, a comparison between the conventional example and the present invention will be made according to Equation 3. If the total thickness of the liquid crystal element is 4t,
In the conventional example,

[0037]

[Equation 4] (Equation 4) t ₁ = t ₂ = 2t (= 1.0 mm), and in the present invention,

[0038]

[Equation 5] (Equation 5) t ₁ = 3t (= 1.5 mm) t ₂ = t (= 0.5 mm).

Then, the maximum deflection amount δ _J in the conventional liquid crystal element is obtained by substituting equation 4 into equation 3,

[0040]

(Equation 6) δ _J = KW / 16t ^{3 Further} , the maximum amount of deflection δ _H in the liquid crystal element of the present invention is obtained by substituting Equation 5 into Equation 3,

[0041]

(Formula 7) (Formula 7) δ _H = KW / 16t ³ . That is, in the present invention, the amount of deformation can be reduced to about 57% as compared with the conventional example.

Further, when the plate thickness ratio when the plate thicknesses are different from each other is expressed as x (x = t ₂ / t ₁ ) based on the equation 3, the maximum deflection amount is expressed as x, and when x is a parameter, x = 1, that is, when the plate thicknesses of the upper and lower substrates are the same, the amount of bending becomes maximum, and under the condition that the total thickness of the liquid crystal elements is the same, it is possible to reduce the amount of bending by changing the plate thickness. .

Further, the deviation between the upper substrate and the lower substrate is caused by the liquid crystal element being bent and deformed, and the deviation amount increases in proportion to the bending amount. The displacement of the substrate can be suppressed.

By connecting the thicker substrate to the supporting member, the weight of the other substrate becomes lighter than the conventional one, and the peeling force can be reduced.

Next, the effect of this embodiment will be described.

According to this embodiment, the deflection amount y of the substrates 31a and 31b can be reduced without increasing the weight and the total thickness of the liquid crystal element P ₂ , and as a result, the deterioration of the image quality and the occurrence of alignment defects are prevented. It can be suppressed, and the impact resistance of the liquid crystal element can be enhanced.

Further, according to the present embodiment, the tensile force acting on the inter-substrate adhesive 11 and the peeling force acting between the upper and lower substrates 31a and 31b and the inter-substrate adhesive 11 are reduced. It is possible to reduce the risk that the adhesive 11 is peeled off from the upper and lower substrates 31a and 31b, or the adhesive 11 extends and the cell gap amount expands. Therefore, the alignment state of the liquid crystal 12 is not disturbed, and the deterioration of image quality and the occurrence of defects can be prevented. This effect is particularly effective in the ferroelectric liquid crystal device.

Further, since the tensile force and the peeling force are reduced as described above, it is not necessary to increase the dispersion density of the adhesive 11, and it is possible to prevent the deterioration of the image quality from this point as well.

Further, according to the present embodiment, since the amount of displacement in the plane direction can be reduced, it is possible to prevent the layer structure of the liquid crystal 12 from being disturbed even when a shock or the like is caused, and to prevent a defective image quality or a deteriorated image quality. it can.

In the above-described embodiment, the upper and lower substrates 31a and 31b are made of the same material (glass) and the lower substrate 31b is thin and light. However, it is not limited to this, and the upper substrate is not limited thereto. 31a may be made of glass, and the lower substrate 31b may be made of a resin lighter than glass. That is, since the lower substrate 31b is light, the tensile force and the peeling force acting on the inter-substrate adhesive 11 and the like are small, and the same effect as that of the above-described embodiment is obtained.

Further, in the above-described embodiment, the liquid crystal element P ₂ is supported by the cell fixing plate 2 in a suspended state, but it is not limited to this, and as shown in FIG. 6, the backlight chassis 16 is used. The elastic member 17 may be interposed between the cell fixing plate 2 and the cell fixing plate 2.

[0052]

As described above, according to the present invention,
When an external force in a predetermined direction acts on the liquid crystal device, the first substrate and the second substrate bend. Here, since the first substrate is formed thicker than the second substrate, for example, when the total thickness of the first substrate and the second substrate is the same as the conventional one, the amount of deflection is Less than before. As a result, it is possible to suppress the deterioration of image quality and the occurrence of alignment defects.

This effect can be obtained even if the first substrate and the second substrate are made of the same material, for example, glass. In addition, such an effect is obtained by the first substrate and the second substrate.
Can be obtained when the second substrate is made of a different material and the second substrate is lighter than the first substrate, for example,
This is obtained when the first substrate is made of glass and the second substrate is made of a resin lighter than the first substrate.

When the first substrate is supported by a supporting member, the adhesive disposed between the substrates may have the second component.
A tensile force according to the own weight of the substrate acts, and a peeling force according to the own weight of the second substrate acts between the adhesive and the substrate. However, since the first substrate is formed thicker than the second substrate, for example, the first substrate and the second substrate are
If the total thickness of the substrate and the
The weight of the substrate becomes smaller than before, and as a result, the force acting on the adhesive or the like becomes smaller than before. Therefore, it is possible to reduce the risk that the adhesive may be peeled off from the substrate or the adhesive may be expanded and the cell gap amount may be expanded. Therefore, the disorder of the alignment state of the liquid crystal can be reduced, and the deterioration of the image quality and the generation of defects can be suppressed. Further, since the tensile force and the peeling force are reduced as described above, it is not necessary to increase the dispersion density of the adhesive, and also from this point, the deterioration of the image quality can be prevented.

Furthermore, when an external force in a predetermined direction is applied to the liquid crystal device, the first substrate and the second substrate are bent and the inner surfaces of both substrates are displaced in the plane direction. Since it is formed thicker than the second substrate, for example, when the total thickness of the first substrate and the second substrate is the same as the conventional one, the deviation amount is small. As a result, the disorder of the layer structure of the liquid crystal can be reduced, and the image quality defect and the image quality deterioration can be prevented.

[Brief description of the drawings]

FIG. 1 is a sectional view for explaining a schematic structure of a conventional liquid crystal device.

FIG. 2 is a detailed cross-sectional view for explaining the structure of a liquid crystal element.

FIG. 3 is a diagram for explaining a conventional problem.

FIG. 4 is a cross-sectional view for explaining another conventional example relating to a support structure for a liquid crystal element.

FIG. 5 is a cross-sectional view for explaining the structure of a liquid crystal element according to the present invention.

FIG. 6 is a cross-sectional view for explaining another example of the support structure of the liquid crystal element.

[Explanation of symbols]

2 Cell Fixing Plate (Supporting Member) 10 Spacer 11 Adhesive between Substrates 12 Ferroelectric Liquid Crystal 13a, 13b Polarizing Plate 15 Encapsulating Material 30 Liquid Crystal Device 31a Glass Substrate (First Substrate) 31b Glass Substrate (Second Substrate) P ₂ liquid crystal element

Claims (9)

[Claims] 1. A liquid crystal element for displaying images by transparent first and second substrates arranged in parallel and liquid crystal sandwiched between these substrates and driving the liquid crystal by a peripheral drive circuit. A liquid crystal element, characterized in that the first substrate and the second substrate are different in plate thickness. 2. The liquid crystal device according to claim 1, wherein the first substrate and the second substrate are formed of the same material. 3. The liquid crystal device according to claim 2, wherein both the first substrate and the second substrate are made of glass. 4. The second substrate is thinner than the first substrate, the first substrate and the second substrate are made of different materials, and the second substrate is the first substrate. 2. The liquid crystal device according to claim 1, wherein the liquid crystal device is lighter than the first substrate. 5. The liquid crystal according to claim 4, wherein the first substrate is made of glass, and the second substrate is made of a resin lighter than the first substrate. element. 6. The liquid crystal device according to claim 1, wherein an adhesive in the form of fine particles is dispersed between the first and second substrates to bond the two substrates together. 7. The liquid crystal device according to claim 1, wherein the liquid crystal is a ferroelectric liquid crystal. 8. A method of manufacturing a liquid crystal element having a constant total thickness, which is formed by sandwiching a liquid crystal between a pair of substrates, wherein substrates having different thicknesses are used as the pair of substrates, respectively. A method for manufacturing a liquid crystal element. 9. A substrate provided with the liquid crystal element according to claim 1 and a support member for supporting the liquid crystal element, and having a thick plate thickness of the first or second substrate. Is supported by the support member.