JPS6132817A - Liquid crystal display panel and its manufacture - Google Patents

Abstract

PURPOSE:To produce a small pretilt angle and to attain uniform orientation by laminating an inorg. orienting film of an inorg. orienting agent on an org. orienting film of an org. orienting agent. CONSTITUTION:Each glass substrate 1 having an electrically conductive transparent film 2 of 400Angstrom thickness is spin-coated with polyimide as an org. orienting agent, and the polyimide is dried, cured, and rubbed with polyester cloth to form an org. orienting film 3. This film 3 is spin-coated with a silane coupling agent as an inorg. orienting agent 4, and the coupling agent is dried and cured. A liq. crystal is sealed in the gap between such glass substrates 1 to obtain a liq. crystal display panel. Molecules of the liq. crystal are oriented in the rubbing direction of the polyimide, and the pretilt angle can be reduced to about 0.5 deg.. Thus, a small tilt angle can be produced without deteriorating uniformity in orientation, and a liq. crystal panel having high contrast and enabling high duty drive by acceleration can be provided.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a liquid crystal display panel in which an organic alignment film and an inorganic alignment film are laminated.

The field of use for liquid crystals has expanded from calculators and digital watches to display devices for office automation equipment and televisions. As with other display panels, these liquid crystal display panels are also required to have a high-speed display switching response.

[Conventional technology]

This article describes nematic liquid crystals and alignment processing. Manetic liquid crystal has the property that the molecular axes of all liquid crystal molecules are aligned in the same direction, and when it is held in a gap between smooth substrates, it is oriented parallel to or perpendicular to the substrate surface depending on the surface condition of the substrate.

Nematic liquid crystal can be horizontally aligned by providing a special thin film (alignment film) on the surface of the substrate. Furthermore, by rubbing the alignment film surface in a certain direction with a special cloth or the like (rubbing), multiple micro grooves are formed along the certain direction, thereby aligning the molecular axes of all liquid crystal molecules in the rubbing direction. can be matched.

Even in the case of horizontal alignment, the liquid crystal molecular axes are not completely parallel to the substrate surface but are oriented at a minute angle relative to the substrate surface. (This angle is called the pretilt angle.) The liquid crystal molecules are also aligned according to this angle.

The uniformity of these alignments and the size of the pretilt angle are closely related to the display characteristics of the liquid crystal display panel. The more the molecular axes of liquid crystal molecules are aligned in the rubbing direction, the higher the contrast.
The smaller the pretilt angle is, the steeper the electro-optical change is, and the number of time-division drive divisions can be increased.

Conventionally, the alignment material has been polyimide, an organic alignment agent that is relatively soft and has a large pretilt angle.

Polyvinyl alcohol or an inorganic alignment agent that is relatively hard and has a small pretilt angle S 1021CeOn, WOs
, a silane coupling agent, and a titanium coupling agent were used as a single layer film.

[Problem that the invention seeks to solve]

In a liquid crystal display panel, good display characteristics cannot be obtained unless alignment is made uniform and the pretilt angle is made small.

Conventionally, an organic alignment film made of an organic alignment agent and an inorganic alignment film made of an inorganic alignment agent were used individually. Therefore, in the former case, as shown in FIG. 3, since the material is relatively soft, it is easy to rub and the uniformity of orientation is good, but the angle of the slope of the groove a increases due to rubbing, and the pretilt angle increases accordingly. In the latter case, as shown in FIG. 4, the pretilt angle is sufficiently small because it is relatively hard, but the uniformity of alignment is insufficient and the contrast may deteriorate.

In order to reduce the pretilt angle using only an organic alignment film, it is possible to perform rubbing while controlling the pressure appropriately, but this control is extremely difficult, so it has not been possible to reduce the pretilt angle.

In this way, it has not been possible to satisfy both the uniformity of orientation and the small pretilt angle.

[Means for solving problems]

In order to solve the above problem, in a liquid crystal display panel in which liquid crystal is sealed between two mutually facing insulating substrates, each of which has a transparent electrode and an alignment film laminated on their opposing surfaces, the alignment film is made of an organic alignment agent. and an inorganic alignment film made of an inorganic alignment agent are laminated with the inorganic alignment film as an upper layer, and the surface of the organic alignment film is subjected to a rubbing treatment, and its production. provide a method.

[Effect]

By laminating an organic alignment film made of an organic alignment agent and an inorganic alignment film made of an inorganic alignment agent with the inorganic alignment film as an upper layer, a low pretilt angle can be created and the alignment can be made uniform. Can be done.

〔Example〕

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

FIG. 1 shows a side view of the liquid crystal display panel of the present invention. In the figure, 1 is a substrate (glass) 2 is a transparent conductive film, 3 is an organic alignment agent such as polyimide, and 4 is an inorganic alignment agent such as a silane coupling agent.

400 people in advance transparent conductive 1! j! Polyimide (Nitto Denko Department, JR-100) was spin-coded as an organic alignment film 3 on the glass substrate 1 on which 2 was formed, at 300 Orpm for 60 seconds, and dried and cured at 300°C for 10 minutes.
Rub with polyester cloth. A silane coupling agent (Shin-Etsu Chemical Co., Ltd., Shin-Etsu Chemical Co., Ltd.,
Spin code KBMI 03) at 300 Orpm for 30 seconds and dry cure at 150° C. for 5 minutes. The thickness of the organic alignment film and inorganic alignment film is 500 to 100, respectively.
Approximately 0 people.

When a liquid crystal display panel was formed using the glass substrate subjected to the above alignment treatment and liquid crystal was sealed, the alignment direction of the liquid crystal molecules coincided with the rubbing direction of the polyimide, even though the silane coupling agent was not rubbed.

Moreover, the pretilt angle is 3° or more when using only an organic alignment film.
While the angle was 4°, when an organic alignment film and an inorganic alignment film were laminated, the angle could be reduced to about 0.5°.

〔Effect of the invention〕

According to the present invention, it is possible to realize a low tilt angle without impairing alignment uniformity, and therefore it is possible to provide a liquid crystal display panel with high contrast and high duty ratio driving at high speed.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the main parts of the present invention in detail, Fig. 2 is a diagram showing the entire liquid crystal display panel of the present invention, and Figs. 3 and 4 show conventional organic alignment agents and inorganic alignment agents, respectively. FIG. 2 is a diagram of main parts of a liquid crystal display panel used alone. In the figure, 1 is a glass substrate, and 2 is a transparent conductive film. 3 is an alignment film made of an organic alignment agent such as polyimide. 4 is an alignment film made of an inorganic alignment agent such as a silane coupling agent, 5 is a liquid crystal, 6 is a polarizing plate, and 7 is a reflecting plate. 1. 2nd Bi% 3. Judgment 4th

Claims (3)

[Claims] (1) In a liquid crystal display panel in which liquid crystal is sealed between two mutually opposing insulating substrates on which transparent electrodes and an alignment film are laminated on their respective opposing surfaces, the alignment film is an organic alignment film made of an organic alignment agent. A liquid crystal display panel characterized in that an inorganic alignment film consisting of a film and an inorganic alignment agent is laminated with the inorganic alignment film as an upper layer, and the surface of the organic alignment film is subjected to a rubbing treatment. (2) The organic alignment film is made of polyimide or polyvinyl alcohol, and the inorganic alignment film is made of one of SiO_2, CeO_2, WO_3, a silane coupling agent, and a titanium coupling agent. LCD display panel. (3) In a liquid crystal display panel in which liquid crystal is sealed between two mutually opposing insulating substrates on which transparent electrodes and an alignment film are laminated on their respective opposing surfaces, the alignment film is an organic alignment film made of an organic alignment agent. Having an inorganic alignment film consisting of a film and an inorganic alignment agent, applying a rubbing treatment to the surface after depositing the organic alignment film, and then depositing the inorganic alignment film in a laminated manner on the surface of the organic alignment film. A method for manufacturing a liquid crystal display panel characterized by: