JPH04366921A - Liquid crystal display element with diaphragm - Google Patents

Abstract

PURPOSE:To generate no domain even in ultrasonic-wave operation endurance and prevent a raindrop removing function from deteriorating. CONSTITUTION:Spacers are interposed between two substrates which have transparent electrode layers and orienting films formed on their mutually opposite surfaces and the peripheral part is sealed with a seal material to form a liquid crystal panel; and liquid crystal is injected into the liquid crystal panel and diaphragms are adhered to both the substrates to form the liquid crystal display element with the diaphragms. In this liquid crystal display element, the spacers are dispersed and oriented in the orienting films to 6500-24000 pieces/cm<2> density. Consequently, the cell gap can be held uniform even during the ultrasonic-wave endurance and the generation of a domain is nearly eliminated. Further, the upper limit of the spacer dispersion density is controlled to sufficiently secure the vibration of the substrates in ultrasonic-wave operation, so desired raindrop removing performance is obtained.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device with a diaphragm.

0002

[Prior Art] Liquid crystal display devices utilize the electro-optic effect of liquid crystals, that is, changes in the optical properties of liquid crystal molecules that occur when an electric field is applied. In addition to being used as display elements, it is also used as anti-glare mirrors in automobiles.

[0003] That is, it is possible to install a liquid crystal sealed in two electrodes on the glass front surface of a mirror, and apply a voltage between the electrodes to make the liquid crystal translucent, thereby obtaining an anti-glare effect of the mirror. It is already known as Japanese Patent Publication No. 48-35384.

On the other hand, in order to remove water droplets that adhere to outside mirrors such as door mirrors and fender mirrors,
In 1983, a device was developed in which a vibrating device using a piezoelectric element was attached to the mirror, and the vibration of the vibrating device vibrated the mirror to atomize and instantly remove water droplets adhering to the reflective surface of the mirror. No. 25658.

Furthermore, in Japanese Patent Application Laid-Open No. 61-67830, in a liquid crystal display element using a plastic substrate, since the substrate has high flexibility, the spacer moves and the cell gap cannot be maintained accurately, resulting in display unevenness. In order to solve the problem of spacers being generated, spacers are formed from an organic insulating material, and at least 10 pieces/cm2 and 60 pieces/c
A liquid crystal display element in which the particles are uniformly dispersed and fixed in an alignment film in a range of less than m2 is disclosed.

Further, Japanese Patent Laid-Open No. 58-62624 proposes a liquid crystal display element in which a spacer member is mixed into an alignment film in order to control the amount of the spacer member and disperse it uniformly.

[0007]

[Problem to be Solved by the Invention] It is desired to develop a liquid crystal mirror with a raindrop removal function that is equipped with a diaphragm for the purpose of removing raindrops that adhere to this liquid crystal anti-glare mirror.The structure of this liquid crystal mirror is shown in Fig. 4. It is assumed that it is something like this.

In FIG. 4, two transparent substrates 1a and 1b are arranged to face each other, transparent electrode layers 2a and 2b are respectively deposited on the opposing surfaces, and alignment films 3a and 3b are further applied thereon. is formed. Note that an Al vapor deposition film 7 is formed on the back surface of the transparent substrate 1b, and a protective film 8
covered by.

After the alignment films 3a and 3b have been subjected to an alignment treatment such as rubbing, glass or plastic particulate spacers 5 are interposed to control the gap between the transparent electrode layers 2a and 2b. The peripheral edges of transparent substrates 1a and 1b are adhered with sealant 4 to assemble a liquid crystal cell.

After the liquid crystal 13 is sealed in this liquid crystal cell,
A diaphragm 10 with a piezoelectric element 12 fixed thereto using an adhesive 11 for fixing the piezoelectric element is adhered to the back surface of the transparent substrate 1b using an adhesive 9 for fixing the diaphragm.

The conventional manufacturing process of this liquid crystal cell with a diaphragm after forming the transparent electrode layer is as follows. Alignment film printing → alignment film curing → rubbing → cleaning → sealant printing → cell assembly (sealant curing) → liquid crystal injection sealing → ultrasonic diaphragm adhesion. In order to prevent the spacers from moving within the liquid crystal cell due to ultrasonic operation, a method is used in which the spacers are mixed into an alignment agent solution during printing of the alignment film and fixed to the alignment film.

However, in this liquid crystal display element with a diaphragm, when the density of the spacers fixed to the alignment film is low, there are few parts to support the substrate, and the cell gap becomes uneven during durability of ultrasonic operation. domain(
color unevenness) is likely to occur. On the other hand, when the density of the spacers fixed to the alignment film is high, the vibration of the substrate of the liquid crystal display element due to ultrasonic waves becomes small, resulting in a disadvantage that the raindrop removal performance deteriorates.

The present invention has been made in order to solve the above-mentioned problems of a liquid crystal display element with a diaphragm provided with raindrop removal performance. An object of the present invention is to provide a liquid crystal display element with a diaphragm having excellent raindrop removal performance.

[0014]

[Means for Solving the Problem] Although the generation of domains can be prevented by increasing the dispersion density of spacers, the raindrop removal performance is degraded. Therefore, the inventors conducted extensive research on the relationship between the dispersion density of spacers, the number of domains generated, and raindrop removal performance. As a result, the present invention was completed based on the new finding that there is a range of spacer dispersion density in which the generation of domains can be minimized without deteriorating the raindrop removal performance.

The liquid crystal display element with a diaphragm of the present invention includes two substrates arranged opposite to each other, transparent electrode layers formed on the opposite surfaces of the substrates, and a transparent electrode layer formed on the transparent electrode layer. a liquid crystal comprising an alignment film formed on the substrate, spacers sprinkled on the alignment film, a sealing material sealing the peripheral edge of the substrate to form a liquid crystal panel, and liquid crystal injected and sealed into the liquid crystal panel. In the display element, a diaphragm having a piezoelectric element is fixed to one of the substrates, and the spacers are dispersed and fixed to the alignment film at a density of 6,500 to 24,000 pieces/cm<2>.

A glass plate or a transparent plastic plate is used as the transparent substrate. If necessary, a polarizing plate is superimposed on the outer surface when two substrates are superimposed. Furthermore, when the liquid crystal cell is used as a liquid crystal anti-glare mirror or the like, it is necessary to form a metal vapor deposited film such as aluminum on one of the transparent substrates to form a reflecting plate.

As the transparent electrode, a thin film of a metal oxide such as tin oxide or indium oxide is generally used. The transparent electrode layers can be formed on opposing surfaces of the substrate by a spray method, a vacuum evaporation method, or a high frequency sputtering method. The electrode configuration can be applied not only to segment electrodes and fixed pattern electrodes but also to matrix electrodes.

The present invention is applied to a liquid crystal cell in which an alignment film is formed by a rubbing method. Forming an alignment film using the rubbing method involves applying an aqueous solution of polyimide or polyvinyl alcohol to form a thin alignment film on the surface of the substrate, and then rubbing the surface in one direction with a cloth (rubbing) to obtain alignment. .

[0019] Furthermore, in the case of a liquid crystal cell with an ultrasonic diaphragm,
In order to prevent the spacers from moving within the liquid crystal cell due to ultrasonic operation, a method is used in which the spacers are mixed into an alignment agent solution during printing of the alignment film, and the spacers are fixed to the alignment film. The dispersion density of spacers can be adjusted by adjusting the concentration of spacers mixed into the polyimide solution.

The sealing agent seals the periphery of the liquid crystal cell, and an organic adhesive such as a thermosetting epoxy adhesive is used as the sealing agent. The liquid crystal cell assembled by heat curing the sealant after bonding the substrates is vacuum degassed before injection of the liquid crystal.

[0021]

[Operation] In the present invention, the spacer is 6500 to 24
Since they were dispersed and fixed on the alignment film at a density of 000 pieces/cm2,
The cell gap can be kept uniform even during ultrasonic operation durability, and almost no domains are observed. Also,
By regulating the upper limit of the spacer dispersion density, it is possible to ensure sufficient vibration of the substrate during ultrasonic operation, so that desired raindrop removal performance can be obtained.

In the present invention, the spacer dispersion density is set to 65
00 to 24000 pieces/cm2 is because the dispersion density is 6.
This is because if it is less than 500 pieces/cm 2 , domains may occur, and if it exceeds 24,000 pieces/cm 2 , the raindrop removal performance will deteriorate.

[0023]

[Example] Examples of the present invention will be explained together with comparative examples to clarify the effects of the present invention. FIG. 4 is a cross-sectional view of a liquid crystal cell with an ultrasonic diaphragm used in this example, and its configuration is as already described in paragraphs 0008 to 0010.

(Example 1) Two transparent substrates 1a and 1
A curved glass plate with a radius of curvature of 1800 mm and a thickness of 0.7 mm was used for b, and transparent electrode layers 2a and 2b each made of ITO (indium tin oxide) and having a thickness of 400 Å were deposited on opposing surfaces. The alignment film 3a is coated with a polyimide solution and dried and cured at 300° C. for 1 hour to a thickness of 150 mm.
It was formed as a 0 Å film.

On the other hand, the alignment film 3b was coated with a spacer-mixed polyimide solution. That is, the spacer 5 has a diameter of 7
Using polystyrene beads of μm, the spacer 5 is added to a polyimide solution at a spacer dispersion density of 1000 to 1000.
After applying the spacer mixed polyimide solution to the substrate 1b, 20
By drying and curing at 0° C. for 1 hour, the spacer 5 was fixed to the substrate 1b via the polyimide. The thickness of the alignment film 3b is 3000 Å. Incidentally, an Al vapor deposited film 7 having a thickness of 1200 Å was formed on the back surface of the transparent substrate 1b and covered with a protective film 8.

Cleaning of the alignment films 3a and 3b after the rubbing treatment was carried out by ultrasonic pure water cleaning. Next, an epoxy sealant 4 is printed on the peripheral edges of the transparent substrates 1a and 1b, and the substrates 1a and 1b are stacked and heated at 180°C for 75 minutes.
The liquid crystal cell was assembled by curing the sealing material 4 by heating for a minute.

After injecting and sealing the liquid crystal 13 into the assembled liquid crystal cell, the diaphragm 10 with the piezoelectric element 12 fixed to the back surface using the adhesive 11 for fixing the piezoelectric element is placed on the back surface of the transparent substrate 1b. 9 was used for adhesion.

The resulting liquid crystal display device with a diaphragm was evaluated for raindrop removal performance and ultrasonic operation durability. The raindrop removal performance was evaluated by inputting DC 12V to the piezoelectric element via a drive circuit. For the evaluation, water droplets were sprayed onto the surface of the substrate 1a, a voltage was applied for 5 seconds, and then the water droplets remaining on the surface were evaluated on the following five scales. Evaluation criteria: 5... No water droplets at all 4... Some water droplets remain in the corners 3... Some water droplets remain in the center 2... Large water droplets remain 1... Quite a few large water droplets remain

[0029] Regarding ultrasonic operation durability, DC
A voltage of 12 V was applied for 5 seconds through the drive circuit, and the device was operated with one cycle of stopping for 30 seconds. After 36,000 cycles, the liquid crystal mirror portion was visually observed to check for the presence or absence of domain generation. The obtained results are summarized in Figure 1.

As shown in FIG. 1, regarding the raindrop removal performance, the average spacer density in the liquid crystal cell is 1000 to 100%.
Up to 00 droplets/cm2, there were no water droplets as per evaluation standard 5, but between 10,000 and 24,000 droplets/cm2, the droplets decreased until a few water droplets remained in the center of evaluation standard 3, which is the practical limit.

[0031] Furthermore, the number of domains generated in every five samples is determined when the average spacer density in the liquid crystal cell is 6500 pieces/cm.
When it is less than 2, 1 to 5 domains have occurred. However, the average spacer density in the liquid crystal cell is 6500 pieces/cm.
When the number exceeds 2, the number of domains generated becomes 0. From the above results, the average spacer density in the liquid crystal cell is 6500~
It was found that within the range of 24,000 particles/cm2, the raindrop removal performance of the liquid crystal cell could be maintained within the practical limit and domain generation could be prevented, confirming the effectiveness of the present invention.

(Example 2) A liquid crystal cell with a diaphragm was manufactured using the same constituent materials and the same method as in Example 1. At that time, the mixing ratio of polyimide and spacer was varied between 2 and 9% by weight. The spacer density in the obtained liquid crystal cell was investigated, and the results are shown in FIG.

In order to set the spacer density in the liquid crystal cell to 6,500 to 24,000 pieces/cm2 as shown in FIG. % was found to be preferable.

(Example 3) A liquid crystal cell with a diaphragm was manufactured using the same constituent materials and the same method as in Example 1. At that time, the density and alignment state of the spacers in the liquid crystal cell were investigated by varying the number of times the substrate on the spacer fixed side was rubbed. The orientation state was evaluated based on the following criteria. Evaluation criteria: 3...Good orientation 2...Some parts are not oriented 1...The results obtained without alignment are shown in FIG.

From the results shown in FIG. 3, the appropriate number of rubbings for the substrate to which the spacers are fixed is in the range of 2 to 8 times, taking into consideration the orientation state, spacer density, and variations thereof. Preferably, the number of times is within the range of 3 to 7 times so that the variation in spacer density is relatively small and an appropriate density can be ensured.

[0036]

Effects of the Invention As described in detail above, the liquid crystal display element with a diaphragm of the present invention is provided by interposing a spacer between two substrates each having a transparent electrode layer and an alignment film formed on their opposing surfaces. In a liquid crystal display element with a diaphragm, in which a liquid crystal panel is formed by sealing the parts with a sealing material, liquid crystal is injected and sealed into the liquid crystal panel, and a diaphragm is bonded to one of the substrates, the spacer is 6,500 to 24,000. It is characterized by being dispersed and fixed on the alignment film at a density of cells/cm2, and the cell gap can be kept uniform even during durability of ultrasonic operation, and almost no domains are observed. In addition, by regulating the upper limit of spacer dispersion density,
Since sufficient vibration of the substrate can be ensured during ultrasonic operation, desired raindrop removal performance can be obtained.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the relationship between the average spacer density in a liquid crystal cell, raindrop removal performance, and the number of domains generated.

FIG. 2 is a diagram showing the relationship between spacer density in a polyimide solution and average spacer density in a liquid crystal cell.

FIG. 3 is a diagram showing the relationship between the number of times of rubbing and the average spacer density and alignment state in a liquid crystal cell.

FIG. 4 is a cross-sectional view of a liquid crystal cell with a diaphragm.

[Explanation of symbols]

1a and 1b substrate
2a and 2b transparent electrode layers 3a and 3b alignment film 4
Sealant 5 Spacer
7 Al film 10 Vibration plate
12 Piezoelectric element 13 Liquid crystal

Claims (1)

[Claims] [Claim 1] Two substrates arranged opposite to each other;
A transparent electrode layer formed on opposing surfaces of the substrate, an alignment film formed on the transparent electrode layer, spacers sprinkled on the alignment film, and a peripheral edge of the substrate are sealed. In a liquid crystal display element comprising a sealing material forming a liquid crystal panel and a liquid crystal injected and sealed into the liquid crystal panel, a diaphragm having a piezoelectric element is fixed to one of the substrates, and the spacer has a diameter of 6,500 to 24,000. pieces/cm2
A liquid crystal display element with a diaphragm, characterized in that the liquid crystal display element is dispersed and fixed on the alignment film at a density of .