JPS6132816A - Rubbing treatment device for liquid-crystal display element substrate - Google Patents

Abstract

PURPOSE:To make rubbing pressure constant, uniform the orientation of liquid- crystal molecules, and to eliminate display irregularity by using an ultrasonic probe as a sensor for rubbing pressure. CONSTITUTION:A liquid-crystal display element substrate 1 is fitted on the surface plate of the rubbing treatment device with an oriented film up, the ultrasonic wave probe 4 is fitted having the surface of a piezoelectric element 9 at the same height with the surface of the oriented film, and a rubbing roll 3 is rubbed against the oriented film of the liquid-crystal display element substrate 1 and also passes over the ultrasonic probe 4. Projection nap of the rubbing roll 3 enters a detection window 8 when the roll passes over the probe to strike the surface of the piezoelectric element 9. Then, the piezoelectric element 9 generates a voltage corresponding to the striking through piezoelectric operation and the induced voltage is applied from a lead wire 10 to a rubbing pressure control circuit 6 through an external lead terminal 11. Consequently, the proper height position of the surface plate 2 is calculated and a driving source 5 is controlled to move up and down the surface plate 2, adjusting the rubbing pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a rubbing treatment apparatus for liquid crystal display element substrates.

The field of use of liquid crystal displays has expanded from calculators and digital watches to TVs and office equipment displays.

In liquid crystal displays, in order to obtain excellent display characteristics, it is desired to uniformize the alignment by controlling the rubbing pressure to a constant level.

[Conventional technology]

In a twisted nematic liquid crystal display panel, liquid crystal molecules are arranged so that their long axes are parallel to the substrate surfaces and that their long axes are shifted by 90 degrees while passing from one substrate to the other.

A method for arranging liquid crystal molecules in this way is to use polyimide, polyvinyl alcohol, 5i02, Cen2 as a substrate.
．． It is common to form a thin film (oriented Ml) of a silane coupling agent or the like, and then perform a step (rubbing) of rubbing the surface in one direction with a cloth or the like. In order to manufacture a liquid crystal display panel with uniform display quality, the pressure during this rubbing must be constant.

These conventional techniques include a method in which the distance between the rubbing roll and the surface plate is visually measured, and a semiconductor pressure sensor is set on the surface plate so that the height of the pressure measurement surface is equal to the height of the substrate. Move so that the center of the pressure sensor is directly below the rubbing roll, measure the rubbing pressure with the rubbing roll rotating, and adjust the height of the rubbing roll 3 or the surface plate so that the rubbing pressure reaches a predetermined value. This is a method of adjusting the

[Problem that the invention seeks to solve]

Conventionally, in order to obtain a liquid crystal display panel with uniform display quality, the distance between the rubbing roll and the surface plate was measured visually, and the rubbing roll was measured using a semiconductor pressure sensor.

The idea was to stabilize the pressure by adjusting the height of the surface plate. However, in the former case of visual inspection, the error is too large and the reproducibility is poor, which often causes poor alignment.

In the case of the latter pressure sensor, since the pressure of the rubbing roll is non-hydrostatic and not constant, it is difficult to accurately measure the pressure.

[Means for solving problems]

To solve the above-mentioned problem, in an apparatus for rubbing an alignment film on the surface of a liquid crystal display element substrate set on a surface plate using a rubbing roll, at least the liquid crystal display element substrate and an ultrasonic probe are placed on the surface plate. A liquid crystal display characterized in that when the ultrasonic probe rubs the alignment film of the liquid crystal display element substrate, the rubbing pressure is detected at the same time, and the rubbing pressure is always controlled to be constant. An apparatus for rubbing an element substrate is provided.

[Effect]

The ultrasonic probe provided on the surface plate detects the rubbing pressure by applying pressure when rubbing the alignment film.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an apparatus for rubbing a liquid crystal display element substrate according to the present invention. In the figure, 1 is a liquid crystal display element substrate made of glass or the like with an organic or inorganic alignment film adhered to its surface, 2 is a surface plate that can be moved up and down, and 3 is movable along the surface of surface plate 2. 4 is an ultrasonic probe; 5 is a driving source such as a solenoid valve that moves up and down a shaft 5' fixed to the surface plate 2; 6 is a driving source according to the output of the ultrasonic probe 4. This is a rubbing pressure control circuit that controls 5 and adjusts the height of the surface plate 2.

FIG. 2 is a diagram illustrating the ultrasonic probe 4.

In the figure, 7 is a surface insulating substrate made of ceramic or the like;
8 is a detection window, 9 is a piezoelectric element made of lithium tantalate, lithium niobate, etc., 10 is a lead wire, 11 is a lead terminal, 12 is an insulating member, and 13 is a metal case. - As shown in the figure, in this rubbing processing apparatus, a liquid crystal display element substrate 1 is mounted on a surface plate 2 with the alignment film facing upward, and an ultrasonic probe 4 is used to place the surface of a piezoelectric element 9 at the same height as the surface of the alignment film. The rubbing roll 3 rubs the alignment film of the liquid crystal display element substrate 1 and passes over the ultrasonic probe 4. During this passage, the protruding bristles of the rubbing roll 3 enter through the detection window 8 and hit the surface of the piezoelectric element 9. Then, the piezoelectric element 9 generates a voltage corresponding to the impact due to piezoelectric action, and the induced voltage is inputted from the lead wire 10 to the rubbing pressure control circuit 6 via the external lead terminal 11.

Thereby, the rubbing pressure control circuit 6 calculates the appropriate height position of the surface plate 2 from the input voltage, and controls the drive source 5 to move the surface plate 2 up and down to adjust the rubbing pressure.

The ultrasonic probe 4 that operates as described above (for example, ultrasonic probe rlON13361J manufactured by Nippon Denpa Kogyo) is set as shown in Fig. 1, and the distance between the rubbing roll 3 and the ultrasonic probe 4 is = The output waveform was measured when the rubbing roll 3 was in contact with the measurement surface of the ultrasonic probe 4 (the surface of the piezoelectric element 9) and was deformed. The results are shown in FIG.

Also, the type (hardness) of the rubbing roll 3, the ultrasonic probe 4
FIG. 4 shows the change in output when the distance between the two points is changed. The hardness of the rubbing roll 3 is A is the softest, and C is the softest.
is the hardest.

Looking at the results, when using the hardest rubbing roll C, a high output voltage is produced by just lightly touching the ultrasonic probe, while when using the softer rubbing roll A, the distance to the ultrasonic probe increases. Even if the length is shortened, the output voltage will only be low. As is clear from this, when an ultrasonic probe is used as a pressure sensor, the rubbing pressure can be measured with good reproducibility.

〔Effect of the invention〕

According to the present invention, since the rubbing pressure can be made constant by using an ultrasonic probe as a rubbing pressure sensor, the uniformity of the alignment of liquid crystal molecules is improved and the liquid crystal display is prevented from display unevenness. An apparatus for rubbing an element substrate can be provided.

[Brief explanation of drawings]

FIG. 1 is a diagram explaining the rubbing processing apparatus of the present invention, and FIG.
The figure is a diagram for explaining the ultrasonic probe of Fig. 1, Fig. 3 is the output waveform of the ultrasonic probe according to the present invention, and Fig. 4 is the type (hardness) of the rubbing roll, the roll and the sensor. FIG. 3 is a diagram according to the present invention showing changes in output voltage when the distance from the device to the device is changed. [Explanation of symbols] 1---------1 liquid crystal display element substrate 2-----,, --- Fixed plate 3--- =-Rubbing roll 4-------- Ultrasonic probe child 5 --- one drive source 6 --- rubbing pressure control circuit 8 ---
-11----Detection window 9-----One piezoelectric element Raw index roll 1st penalty 2nd opening 3rd figure (mm) z4th

Claims (1)

[Claims] In an apparatus for rubbing an alignment film on the surface of a liquid crystal display element substrate set on a surface plate using a rubbing roll,
At least the liquid crystal display element substrate and an ultrasonic probe are provided on the surface plate, and when the ultrasonic probe rubs the alignment film of the liquid crystal display element substrate, the rubbing pressure is detected at the same time, and the rubbing pressure is always detected. A device for rubbing a liquid crystal display element substrate, which functions to control the rubbing pressure at a constant level.