JPS62257129A - Liquid crystal display device and its manufacture - Google Patents

Abstract

PURPOSE:To perform uniform control over the thickness of a cell and to prevent air bubbles from being generated at the low temperature by providing a weir structure for making air bubbles stay inside a notch part and holding air bubbles formed of inert gas whose pressure is lower than external pressure at the weir structure part. CONSTITUTION:To weir 3 for making air bubbles stay is provided inside the notch part (injection hole) 2 and the cell thickness of a liquid crystal display device is adjusted to uniform and accurate cell thickness over the entire liquid crystal cell by scattering spacers 9 made of organic material between opposite electrode substrates 7 and 8 and then pressing the substrates against each other. Consequently, when liquid crystal contracts at low temperature, air bubbles are prevented from being generated at the liquid crystal display part 6 owing to the expansion of existent air bubbles 4. Further, those air bubbles are pressure-reduced air bubbles formed of inert gas and the pressure in the liquid crystal cell is reduced, so the cell is pushed with the external pressure and the cell thickness is held constant with high accuracy, thereby obtaining the liquid crystal display device of sharp display quality.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device that prevents the appearance of bubbles that occur at low temperatures, and a method for manufacturing the same.

[Conventional technology and problems]

Currently, liquid crystal display devices are of the twisted nematic type (hereinafter referred to as rTN Applications are expanding, mainly in the ``type''.

In addition, in recent years, as liquid crystal display devices have become larger, demands have increased for the uniformity and precision of the spacing between two electrode substrates that hold liquid crystal, so-called cell thickness. In particular, the new TN system (Japanese Patent Application Laid-Open No. 60-107020, etc.) uses interference colors due to birefringence for display, and therefore requires high cell thickness accuracy.

Conventionally, in liquid crystal display devices, spacers such as glass fibers are dispersed over the entire surface of the panel and a uniform cell thickness is formed by applying pressure. This conventional liquid crystal display device is shown in FIG.

In FIG. 1, 1 is a sealing material such as epoxy resin containing a spacer, 2 is a notch used as an injection port for injecting liquid crystal into a liquid crystal cell, and 5 is a seal for sealing the notch (injection port) 2. It is a stopper. However, in this structure, the coefficient of thermal expansion is significantly different between the glass constituting the electrode substrate, the inorganic material of the spacer, and the organic material of the liquid crystal material, so when this liquid crystal display element is placed at a low temperature, There was a problem with bubbles forming on the effective display surface. The appearance of these bubbles had the disadvantage of causing black spots on the display surface.

In order to solve this problem, for example, Japanese Patent Laid-Open No. 60-2574
No. 26 proposes the use of a spacer made of a contractible organic polymer material.

However, there are problems in that it is difficult to manufacture organic material spacers with a uniform diameter, and because the spacers are crushed during cell assembly, it is difficult to apply pressure to obtain a desired cell thickness. Also, JP-A-58-12941
No. 9 and Japanese Patent Application Laid-open No. 61-2129 proposed to prevent the appearance of bubbles by partially dispersing spacers and deforming areas other than the display area at low temperatures.

However, in this method, if the spacer is not fixed, there are problems such as a loss of effectiveness due to movement of the spacer and an inability to prevent cell thickness expansion at high temperatures. Further, in Japanese Patent Application Laid-open No. 60-212733, a plan a was proposed in which a pressure relief part having a larger cell thickness than the display part was formed in the non-display part around the cell to prevent the appearance of bubbles at low temperatures. However, this method has the disadvantage that it cannot prevent the cell thickness from expanding at high temperatures, and that an extra area must be provided for the non-display portion.

SUMMARY OF THE INVENTION An object of the present invention is to provide a liquid crystal display device that uniformly controls cell thickness, prevents bubble generation at low temperatures, and does not increase cell thickness at high temperatures, and has good cell thickness accuracy.

[Means for solving problems]

The above problem is solved by disposing a pair of electrode substrates, each having one layer of electrodes, with a spacer in between, and adhesively fixing the substrates with a sealing member, leaving a notch at the periphery. In a liquid crystal display device in which the notch is filled with gas and the notch is sealed with a sealing material, a weir structure is provided inside the notch for retaining air bubbles, and a pressure higher than external pressure is applied to the weir structure. The problem is solved by a liquid crystal display device characterized in that it retains bubbles consisting of an inert gas with a low level of inertness.

In addition, the method for manufacturing the liquid crystal display device of the present invention includes screen printing, etc., on one of the substrates to form a seal pattern including a weir structure pattern for retaining air bubbles that open toward the notch on the inside near the notch. After that, it is overlapped with another substrate on which spacers have been sprinkled and crimped.
A liquid crystal cell having a weir structure for bubble retention is created near the notch, liquid crystal is injected through the notch, and then bubbles made of inert gas are sucked in between the weir structure and the notch through the notch. This method consists of sealing the notch after the

Furthermore, the present invention will be explained in detail.

In the present invention, an inert gas (
(N, Ar, He5Ne, etc.) bubbles are allowed to stay in areas other than the display area. This bubble needs to stay at a certain position other than the display area. By the way, bubbles tend to become circular (minimum surface area) due to surface tension and move toward a wider space. For example, when the cell thickness is uniform, the bubbles 4 sandwiched between the seal members 10 shown in FIG. 2 tend to move toward a wider space. The present invention provides a sealing structure utilizing the above properties inside the notch (liquid crystal injection port) to prevent air bubbles from moving to the liquid crystal display section.

As an example of a specific seal structure having such a structure, the third example is as follows.
Figures (a) and (b) are included. In the figure, reference numeral 3 denotes a weir for retaining air bubbles located inside the notch (inlet) 2. Such a weir structure for bubble retention can be easily formed by screen printing or the like, and the manufacturing process is not particularly complicated compared to conventional methods.

In the present invention, since an inert gas is used as the staying bubbles, an adverse effect on the liquid crystal composition can be prevented. Further, the capacity of the remaining air bubbles is preferably 0.1% or more and 3% or less of the total liquid crystal cell capacity, and if it is 0.1% or less, it is difficult to prevent the cell thickness from increasing due to expansion of the liquid crystal at high temperatures in the liquid crystal display device. difficult. Moreover, if it exceeds 3%, the seal structure for bubble retention becomes thick (and the area of the non-display part increases), which is not preferable.

In the present invention, the cell thickness of the liquid crystal display device is adjusted by spreading spacers made of an inorganic material between opposing electrode substrates and then pressing them together. Therefore, the entire liquid crystal cell has a uniform thickness, and the cell thickness can be maintained with good accuracy.

In the liquid crystal display device having the bubble retention structure of the present invention in the non-display area, it is possible to prevent bubbles from being generated in the liquid crystal display area due to expansion of existing bubbles when the liquid crystal contracts at low temperatures. . In addition, they are bubbles made of inert gas under reduced pressure, and because the pressure inside the liquid crystal cell is reduced, they are pushed by external pressure, and the cell thickness is kept constant and highly accurate, making it possible to obtain a liquid crystal display device with clear display quality. I can do it.

〔Example〕

Next, embodiments of the present invention will be described in detail using the drawings.

An example of the liquid crystal display device of the present invention is shown in FIG.

3 is a weir for bubble retention provided to have a wide space toward the notch (inlet) 2; 4 is a bubble made of a reduced pressure inert gas of 0.5% volume of the liquid crystal cell that remains in a fixed position; 5
is a sealing material that seals the notch (injection port) 2 after injecting the liquid crystal and bubbles. 6 is a display section that does not contain the weir 3 and the bubbles 4.

Next, an example of a method for manufacturing a liquid crystal display device configured as described above will be explained with reference to FIG.

In FIG. 5(a), 7 is one of a pair of electrode substrates which has been oriented by diagonal thin coating with Sin, MgO, etc., rubbing method of rubbing a film of a polymeric substance, etc., as shown in the figure. The spacers 9 are uniformly distributed over the entire surface by a spray method or the like. In FIG. 5(b), a seal made of epoxy resin or the like mixed with a spacer is used on the other electrode substrate 8 that has been subjected to orientation treatment, using a pattern that includes a peripheral seal portion and a weir structure portion for bubble retention. The material is printed using a screen printing method.

Next, the two electrode substrates described above are overlapped as shown in FIG.
A cell shown in Figure (d) was obtained. Next, after injecting liquid crystal into this cell, the cell is uniformly pressurized in an inert gas, and the temperature range is 30 to 30°C below room temperature, which is lower than the N-1 transition temperature of the liquid crystal material.
The extruded liquid crystal is removed by heating to 60°C. Next, the temperature is lowered by 10 to 20° C. and the inert gas is sucked through the cutout (inlet). At this time, by pressurizing the inert gas from normal pressure, the gas can be sucked more completely. Next, the cutout (inlet) 2 is sealed with a sealing material 5 such as epoxy resin under normal pressure or reduced pressure. After solidifying the sealing material 5, the temperature was lowered to room temperature, and the liquid crystal display device shown in FIG. 4 was manufactured.

In addition, when injecting liquid crystal, if the cell is uniformly pressurized and heated, the liquid crystal is injected under an inert gas atmosphere, and the following steps are performed consecutively, the process can be shortened and the liquid crystal injection can be completed. time can be shortened.

〔Effect of the invention〕

With the liquid crystal display device of the present invention, the cell thickness can be maintained uniformly and accurately, and the generation of bubbles at low temperatures can be prevented.
A clear display can be obtained even with the new TN type liquid crystal display device.

Furthermore, the bubble retention weir structure, which is the main part of the liquid crystal display device of the present invention, can be formed by screen printing, and can be produced in the same process as in the production of conventional liquid crystal display devices.

Further, the weir structure also functions as a weir to prevent the sealing material from flowing into the liquid crystal display section.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of a conventional liquid crystal display device, Fig. 2 is an explanatory diagram of bubble movement within a uniform cell, Fig. 3 is an explanatory diagram of a weir structure for bubble retention, and Fig. 4 is an illustration of a wood FIG. 5 is an explanatory diagram showing an outline of the invention, and is an explanatory diagram of a manufacturing method of a liquid crystal display device of the present invention. l...Sealing material 6...Display part 2...Notch part (inlet) 7, 8...Oriented part 3...
Weir Electrode substrate 4...Bubble
9. Spacer 5. Sealing material 10. Sealing member Patent applicant Konishiroku Photo Industry Co., Ltd. Figure 1 Figure 2

Claims (1)

[Claims] 1) A liquid crystal is placed in a cell in which a pair of electrode substrates, each having an alignment layer, are placed facing each other with a spacer interposed therebetween, and are adhesively fixed with a sealing member, leaving a part of the periphery with a notch. In a liquid crystal display device in which the notch is filled with gas and the notch is sealed with a sealing material, the notch has a weir structure for retaining air bubbles, and a pressure higher than external pressure is applied to the weir structure. 1. A liquid crystal display device characterized by retaining bubbles made of an inert gas having a low level of inertness. 2) A pair of electrode substrates, each having an alignment layer, are arranged facing each other with a spacer in between, and a liquid crystal is filled in a cell formed by adhering and fixing with a sealing member, leaving a part of the peripheral edge with a notch, and A method of manufacturing a liquid crystal display device in which a portion of the liquid crystal display device is sealed with a sealing material, wherein one substrate includes a weir structure pattern for retaining air bubbles opened toward the notch inside near the notch. A seal pattern is printed and applied, and then it is stacked and crimped with another substrate on which spacers have been sprinkled, creating a liquid crystal cell with a weir structure for air bubble retention near the cutout, and liquid crystal is poured from the cutout. A method for manufacturing a liquid crystal display device, comprising: injecting the gas into the weir structure, and then sucking bubbles made of inert gas between the weir structure and the notch through the notch, and then sealing the notch.