JPH0287114A - Injecting method for light crystal cell - Google Patents

Abstract

PURPOSE:To manufacture a uniform cell by applying force to the liquid crystal cell in two opposite directions perpendicular to the light crystal cell substrate during a liquid crystal injecting process. CONSTITUTION:The liquid crystal cell 1 is installed in a press jig 2 and plates 3 and 4 which have plane accuracy are applied with a force vertically by torque screws 5. At this time, the liquid crystal cell is fixed with the force of 1kg/cm<2>, and while a vacuum tank is evacuated by an external vacuum pump to 1X10<-4>(Torr), the cell is heated by a heater 6 uniformly to 150 deg.C; and liquid crystal with ferroelectricity is dripped from a dispenser 7 to cover the injection hole of the cell; then N2 is admitted to the vacuum tank at a rate of 20cc per minute to the atmospheric pressure. Thus, uniform cell thickness is obtained by applying the force which is uniform in the cell surface in the opposite directions perpendicular to the substrate to an extent where the cell does not expand so that the liquid crystal is prevented from entering the cell too much.

Description

Detailed Description of the Invention (Field of Application of the Invention) The present invention provides a method for injecting liquid crystal into a liquid crystal cell in which a spacer having adhesiveness and elasticity is interposed, using a vacuum injection method. Therefore, we propose a method to prevent the liquid crystal cell from expanding and excessively injecting liquid crystal into the cell.

(Prior Art) As a method for injecting liquid crystal into a liquid crystal cell, there is a known liquid crystal injection method using a vacuum. In particular, as a method for injecting a liquid crystal cell using a liquid crystal material exhibiting ferroelectricity, there is a patent filed by the applicant (No. 175192 of 1960). The outline is that the entire liquid crystal cell is placed in one vacuum chamber, the inside of the cell is evacuated, the injection port of the cell is filled with liquid crystal material, and the pressure inside the chamber is gradually increased to spread the liquid crystal material inside the cell. This is a method of injection.

In addition, liquid crystals generally have birefringence, and as a result, it is necessary for liquid crystal cells to have a uniform spacing between a pair of substrates that make up the cell.
It is known that serious defects such as color unevenness occur. Therefore, conventionally, in order to prevent cell thickness from shrinking or expanding, adhesive spacers and non-adhesive spacers are mixed in the cell, and the adhesive spacers are used to bond the pair of upper and lower substrates that make up the liquid crystal cell. Many structures were adopted. However, in this structure, when the liquid crystal contracts due to a temperature drop after liquid crystal injection or a phase transition, the cell thickness cannot be similarly contracted, resulting in a problem that a portion where no liquid crystal is present appears in the cell. As a countermeasure to this problem, attempts have been made to make the adhesive spacer stretchable so that the cell thickness can shrink as the liquid crystal contracts, but in this case, when injecting the liquid crystal using the vacuum injection method, the adhesive Due to the elongation of the spacer, the cell swells, resulting in the same result as when no spacer is used, and an excessive amount of liquid crystal enters the cell, resulting in a problem that a uniform cell thickness cannot be obtained.

(Structure of the Invention) In order to solve this problem, the present invention interposes only a spacer having adhesiveness and stretchability, or a spacer having adhesiveness and stretchability and a spacer without adhesiveness at the same time. When injecting liquid crystal into a liquid crystal cell using a vacuum method, in order to prevent excessive penetration of liquid crystal into the cell, the size of the cell must be such that it will not expand in the opposite directions perpendicular to the substrate, and the cell surface It is characterized by applying uniform force within the area.

The present invention will be explained below according to examples.

(Example) FIG. 1 shows an injection device for a liquid crystal cell using the present invention.

The liquid crystal cell 1 was installed inside the press jig 2, and a force was applied from the top and bottom by a torque screw 5 using a plate 3.4 having a flat surface accuracy. In this example, the liquid crystal cell is
The cell was fixed with a force of 1.5 kg/cm.Then, the vacuum chamber was raised to a pressure of 1 x 10 cm using an external vacuum pump.
The cell was evacuated until -' (Torr), and at the same time the cell was uniformly heated to 150° C. by the heater 6. Thereafter, liquid crystal exhibiting ferroelectricity was dripped from the dispenser 7 so as to block the injection port of the cell, and later, N2 was introduced into the vacuum chamber at a rate of 20 cc per minute to return the pressure to atmospheric pressure.

FIG. 2(A) shows the distribution of cell thickness after vacuum injection when no pressure is applied as a comparative example.

FIG. 2 CB) shows the distribution of cell thickness after vacuum injection using the method of applying pressure according to the present invention.

However, the points marked with x are the measurement points, and the unit of thickness is μm.

(Effect) In liquid crystal cells, non-uniform cell thickness causes color unevenness,
Furthermore, since this leads to variations in driving conditions and a deterioration in display quality, the present invention, which can produce uniform cells, was very effective.

In particular, in the case of liquid crystal cells that have adhesive and stretchable spacers interposed between them, even if the cells have a uniform thickness when they are bonded together, the cell thickness becomes uneven during the subsequent process, and it is difficult to repair the cell thickness. becomes difficult or impossible.

By using the method of the present invention, the cell thickness did not change during the liquid crystal injection process, and furthermore, no portions of the cell where no liquid crystal was present appeared, thereby preventing deterioration in display quality.

[Brief explanation of drawings]

FIG. 1 shows a schematic diagram of an injection device used in the present invention. FIG. 2(A) shows the thickness distribution of a liquid crystal cell obtained by the conventional injection method. FIG. 2(B) shows the thickness distribution of a liquid crystal cell manufactured by the injection method of the present invention. LCD cell press jig・Plate with flatness accuracy・Torque press heater dispenser rotary pump

Claims (1)

[Claims] 1. When injecting liquid crystal into a liquid crystal cell with an adhesive and stretchable spacer using a vacuum injection method,
A method for injecting a liquid crystal cell, characterized in that force directed toward the liquid crystal cell is applied at least once during the liquid crystal injecting step from two opposing directions perpendicular to the liquid crystal cell substrate.