JP2012189856A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display device capable of displaying a high-quality image by preventing peeling of an alignment layer caused by rubbing processing.SOLUTION: In a driving wiring area other than a display area and at a frame part in a liquid crystal display device, an ITO film is arranged at a level difference part caused by arranging especially a metal wire, and an alignment layer is arranged on the ITO film. As a result, adhesion of the alignment layer is improved even at the level difference part in the driving wiring area and at the frame part, and peeling of the alignment layer at the level difference part caused by rubbing processing is reduced.

Description

  The present invention relates to a liquid crystal display device having an alignment film for controlling the alignment state of liquid crystal molecules.

  A liquid crystal display device is widely used as a display function for a flat-screen TV, a mobile phone, and the like. With the widespread use, the improvement in image quality such as high contrast, high brightness, and high resolution of the liquid crystal display device is remarkable.

  A liquid crystal display device has a structure in which a liquid crystal layer is sandwiched between a TFT array substrate having active elements, drive wiring, pixel electrodes, and the like and a counter substrate having a color filter for color display. The TFT array substrate has a structure in which active elements, drive wiring, pixel electrodes, etc. are laminated on a glass substrate via an insulating film, etc., and the orientation of liquid crystal molecules is controlled at the interface with the liquid crystal layer. An alignment film to be performed is installed. The counter substrate has a structure in which a light blocking layer called a black matrix, a color filter, a counter electrode, etc. are laminated on a glass substrate, and an alignment film that controls the alignment of liquid crystal molecules at the interface with the liquid crystal layer. Is installed.

  As a method for controlling the alignment of liquid crystal molecules, an alignment control function is given by performing a rubbing process that rubs the surface of the alignment film with a rubbing cloth made of cotton, rayon or the like wound around a roll.

  In addition, the alignment control function imparted by non-contact includes photo-alignment treatment, and a technique for expressing the alignment control function by irradiating polarized ultraviolet rays to an alignment film made of a compound having a photoreactive functional group is also proposed. (For example, refer to Patent Document 1).

JP-A-11-133429

  In the rubbing process in which the surface of the alignment film is rubbed with the rubbing cloth, the rubbing cloth and the alignment film come into contact with each other during the rubbing, so that the alignment film is easily peeled off. In order to control the alignment state of the liquid crystal material, the alignment film is all set in a range in contact with the liquid crystal layer by an offset printing method or an inkjet method. If the alignment film is not provided, the alignment of the liquid crystal molecules cannot be controlled, causing problems such as light leakage.

  In the display area of the liquid crystal display device, an alignment film is provided on the display ITO electrode. However, an alignment film is provided on the insulating film in the drive wiring area in the frame portion outside the display area. The adhesion between the insulating film and the alignment film is weak. In particular, the TFT array substrate has a laminated structure such as a metal wiring and thus has many steps. FIG. 2 shows a cross-sectional configuration of a driving wiring area of a conventional liquid crystal display device. As shown in the drawing, a drive wiring area 9 is a region between a sealing material 8 for bonding the substrate 1 and a counter substrate (not shown) and a display area 10 for displaying an image. In the drive wiring area 9, a metal material such as Mo or Al is patterned into a predetermined shape to form the gate wiring 3. Similarly, the gate wiring 3 is formed in the display area 10. On the gate wiring 3, a gate insulating film 2 for electrically insulating from a Data wiring (not shown) and an insulating film 4 for protecting the Data wiring are provided. In the display area 10, the display ITO electrode 7 is provided on the insulating film 4, and the alignment film 6 is provided thereon. However, in the drive wiring area 9, ITO or the like is not installed on the insulating film 4, and the alignment film 6 is installed directly on the insulating film 4.

  FIG. 3 is a cross-sectional view illustrating a rubbing process of the conventional liquid crystal display device shown in FIG. During the rubbing process, the rubbing roll 11 moves in a specific traveling direction 12 while rotating. When the rubbing roll 11 passes through the drive wiring area 9, the step portion 13 of the gate wiring 3 comes into contact with the rubbing roll 11. When the rubbing roll 11 comes into contact with the stepped portion 13, a large stress is applied, and the alignment film is easily peeled off at the stepped portion 13, and there is a problem that the peeling residue reduces display quality.

  An ITO film is arranged in the drive wiring area outside the display area of the liquid crystal display device, particularly in the stepped portion of the laminated structure by metal wiring in the same manner as the display area, and the layer structure of the stepped portion is lower than the metal wiring, insulating film, Alignment film peeling countermeasure ITO, It is set as the layer structure used as an alignment film.

  According to the present invention, it is possible to improve the adhesion of the alignment film by placing an ITO film below the alignment film even in the step portion of the drive wiring area, and even if stress is applied to the step portion by rubbing treatment or the like, the alignment film peels off. Can be reduced, and a high-quality image can be obtained.

1 is a schematic cross-sectional view showing a liquid crystal display device according to Example 1. FIG. It is typical sectional drawing which shows the conventional liquid crystal display device. It is typical sectional drawing which shows the conventional liquid crystal display device. It is a typical top view which shows a liquid crystal display device.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a cross section of a drive wiring area of the liquid crystal display device of this embodiment. As shown in FIG. 1, a metal material such as Mo or Al is patterned on the substrate 1 in a predetermined shape to form a gate wiring 3. The gate line 3 is formed in both the display area 10 and the drive line area 9. Here, a region between the sealing material 8 for joining the substrate 1 and the counter substrate (not shown) and the display area 10 for displaying an image is the drive wiring area 9. On the gate wiring 3, a gate insulating film 2 for electrically insulating from a Data wiring (not shown) and an insulating film 4 for protecting the Data wiring are provided. In the display area 10, the display ITO electrode 7 is formed on the insulating film 4, and the alignment film 6 is formed on the display ITO electrode 7.

  In the drive wiring area 9, an alignment film peeling countermeasure ITO 5 is provided on the insulating film 4 so as to cover the gate wiring 3. The alignment film peeling countermeasure ITO 5 and the display ITO electrode 7 can be arranged in the same material and in the same process. An alignment film peeling countermeasure ITO 5 is formed so as to cover the gate wiring 3 in the drive wiring area 9. Since ITO and alignment film have strong adhesion, alignment film peeling that occurs in a rubbing process or the like can be reduced.

  FIG. 4 is a plan view showing the appearance of the liquid crystal display device. As shown in the figure, in the drive wiring area 9 outside the display area 10, the alignment film peeling countermeasure ITO is provided above the gate wiring to improve the adhesion of the alignment film, thereby preventing the alignment film peeling. The alignment film peeling prevention ITO is provided between the insulating film and the alignment film.

DESCRIPTION OF SYMBOLS 1 Substrate 2 Gate insulating film 3 Gate wiring 4 Insulating film 5 Alignment film peeling prevention ITO
6 Alignment film 7 ITO electrode for display 8 Sealing material 9 Wiring area for driving 10 Display area 11 Rubbing roll 12 Advancing direction of rubbing roll 13 Stepped portion

Claims (1)

  In a liquid crystal display device including a substrate in which a gate wiring, a gate insulating film, an insulating film for protecting a data wiring, and an alignment film are sequentially stacked, a frame portion of the liquid crystal display device is generated upward by the gate wiring A liquid crystal display device, wherein an alignment film peeling prevention ITO is provided between the insulating film and the insulating film so as to cover the stepped portion.