JP2584165B2 - Manufacturing method of liquid crystal image display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal panel having an image display function, in particular, an active type liquid crystal image display device having a switching element for each picture element. The present invention relates to an arrangement pattern of scanning lines and a rubbing method for aligning liquid crystal.

[0002]

2. Description of the Related Art First, twist nematic (TN)
An outline of an active matrix type liquid crystal image display device using a liquid crystal material of a liquid crystal type will be described. FIG. 4 shows a main configuration diagram thereof.

A liquid crystal image display device is obtained by bonding an active substrate 1 and a counter electrode substrate 7 with a sealing material 8 and sealing liquid crystal therein. On the active substrate 1, scanning lines 2 and 3 for operating switching elements in the picture element section 9 and signal lines 4 and 4 'for transmitting image signals are formed by enclosing liquid crystal from the picture element section 9. It is wired outside a certain area. These wirings are respectively connected to a scanning line mounting terminal 5 and a signal line mounting terminal 6 for connecting a wiring (not shown) for transmitting an external electric signal. In addition, a function (not shown) for repairing the disconnection of the wiring is often provided on the scanning lines 2 and 3 and the signal lines 4 and 4 'outside the area of the picture element portion 9. In FIG. 4, the scanning line 3 is shown as a function for repairing a disconnection of the wiring, but may have a configuration corresponding to the scanning line mounting terminal 5 in some cases. The orientation of the liquid crystal is determined by the counter electrode substrate 7 and the active substrate 1.
(Rubbing) a plurality of times in a certain direction with a cloth on the side in contact with the liquid crystal. At this time, the rubbing direction a of the active substrate and the rubbing direction b of the counter electrode substrate are substantially 90 degrees.
It is rubbed to the degree angle. In this way, a liquid crystal image display device is created.

Next, a sectional structure of the picture element portion 9 will be described.
FIG. 5 shows a main cross-sectional structure. On the active substrate 1,
Scanning lines 2 and 3, dielectric 12, semiconductor 13, signal line 4,
4 ', the drain electrode 10 and the picture element electrode 11 are patterned to form a switching element. A light-shielding layer 17 on which a thin film of metal or the like for preventing malfunction of the switching element due to light is provided on the counter electrode substrate 7.
A colored layer 16 provided with an organic thin film containing one or both of a dye and a pigment for providing a color display function is provided at a position facing the pixel electrode 11. Further, on the entire surface of the counter electrode substrate 7, a counter electrode 19, which is one electrode for operating the liquid crystal 15, is provided. In order to align the liquid crystal, a polyimide-based organic thin film is formed on the entire surface of the active substrate 1 and the counter electrode substrate 7 as an alignment film 14 over the entire surface. In order to convert the operation state of the liquid crystal into the transmission intensity of light, a film-shaped polarizing plate is disposed on the entire surface of the active substrate 1 and the counter electrode substrate 7 opposite to the side in contact with the liquid crystal.

Next, driving of the liquid crystal image display device will be described. FIG. 6 shows a waveform diagram of the main drive potential of one picture element. The potential Vg20 of the scanning line and the potential Vc of the counter electrode in FIG.
The potential Vs22 of the signal line 21 corresponds to the potential applied to the scanning lines 2 and 3, the counter electrode 19, and the signal lines 4 and 4 'of FIGS. When the potential Vg20 of the scanning line becomes more positive than the potential Vc21 of the counter electrode and the potential of the electron Vs22 of the signal line, the switching element is turned on for the first time and the potential Vs22 of the signal line is changed from the signal lines 4 and 4 'of FIG.
3. The signal is transmitted to the pixel electrode 11 via the drain electrode 10 and a signal is applied to the liquid crystal 15. The signal applied to the liquid crystal is applied to the liquid crystal 1 until the next switching element is turned on.
5 is stored. Since the TN type liquid crystal is driven by an AC potential, the potential Vs22 of the signal line is equal to the potential Vs of the counter electrode.
c21 is a positive / negative AC signal (NT
In the case of the SC system, a period of 30 Hz is applied. However, in practice, the potential Vg20 of the scanning line is lower than that of the dielectric 1 in FIG.
2, the liquid crystal 15 is applied to the liquid crystal 15, and a different DC component is applied to the liquid crystal when the potential Vs22 of the signal line is positive and negative with respect to the potential Vc21 of the counter electrode. For this reason,
Even if the liquid crystal is operated at a certain drive potential, the brightness of the liquid crystal image display device flickers (flicker) at a cycle of 30 Hz. In order to prevent the flicker from being perceived by human eyes, the potential Vc21 of the counter electrode and the potential Vs2 of the signal line are reduced in order to reduce the DC component applied to the liquid crystal.
2 is adjusted by shifting the potential in parallel to the potential Vg20 of the scanning line.

With the above configuration and driving, an active matrix type liquid crystal image display device using a TN type liquid crystal material has been put to practical use.

[0007]

However, in the conventional liquid crystal image display device as described above, when an image is continuously displayed, as shown in FIG. 7, other than the picture element portion 9 near the rubbing start point of the active substrate 1, as shown in FIG. In a region where the liquid crystal is filled, a region 23 in which the voltage holding ratio of the liquid crystal is deteriorated from a certain scanning line 3 to the picture element portion 9 is generated. In this area, the holding state of the image signal applied to the liquid crystal is very bad. For example, when a liquid crystal image display device that performs a dark display when the liquid crystal is not operated displays a bright white, only this portion has a dark white display. Display reliability. This is for the following reason.

First, when rubbing is performed on the orientation of the liquid crystal, a state occurs in which the closer to the vicinity of the rubbing start point, the higher the adhesion density of extremely small foreign matter on a microscope level. The adhered foreign substance is one in which the substrate is rubbed a plurality of times with a cloth, that is, the alignment film which has been scraped off from the substrate in the living room and adhered to the cloth has adhered to the substrate again in the rubbing. FIG. 8 shows the state of the distribution of the adhesion of the foreign matter. The foreign substances 24 on the active substrate side are larger than the foreign substances 25 on the counter electrode substrate side. This is because the active substrate 1 has a more complicated uneven shape on the substrate surface than the counter electrode substrate 7, and the friction with the cloth during rubbing is increased. The foreign matter 24 of the active substrate was considerably attached to the signal line 4 ′ and the scanning line 3 other than the picture element portion 9 near the rubbing start point, but was hardly found in the picture element portion 9. This is because when rubbing, the cloth is constantly adsorbing and adhering to the substrate surface, and a constant balance is maintained under constant friction, but there is no flat pattern at the rubbing start point. When the scanning line 3 and the signal line 4 ′ approach a certain area from the surface, the friction of the rubbing sharply increases, and the alignment film adhering to the cloth in a minute amount causes the scanning line 3 and the signal near the rubbing start point. This is because it is almost deposited on the line 4 '. Since the surface irregularities of the active substrate 1 hardly change between the picture element portion 9 and the scanning lines 2 and 3 and the signal lines 4 and 4 'other than the picture element portion 9, even if the rubbing reaches the No adhesion occurs.

First, in order to prevent the image flicker from being perceived by the human eye, the direct current component applied to the liquid crystal generated by the potential of the scanning line is set so that the signal line potential and the counter electrode potential are parallel to the scanning line potential. In this case, the DC component applied to the liquid crystal is very small in the picture element portion 9 in FIG. 8, but the scanning line surrounded by the sealing material 8 other than the picture element portion 9 in FIG. The liquid crystal on 2 and 3 (this region is about 1 to 3 mm in order to secure a production margin so that the sealing material 8 when the active substrate 1 and the counter electrode substrate 7 are bonded with the sealing material 8 does not spread and enter the picture element portion 9. The cross-sectional structure of the substrate in this region is such that the counter electrode 19 and the alignment film 14 shown in FIG. The dielectric 12 and the alignment film 14 are formed The that), the second state that a large DC component from being applied occurs. This is because the structure on the scanning lines 2 and 3 is different between the picture element portion 9 and the other portions. Therefore, the potential of the counter electrode and the potential of the signal line with respect to the scanning line potential for minimizing the DC component applied to the liquid crystal. Is different.

When these first and second states interact to drive the liquid crystal image display device continuously, the scanning lines 3 are arranged near the rubbing start point of the active substrate having a large foreign substance adhesion density during rubbing, and the liquid crystal display device is driven. In the filled area,
Foreign matter attached by the DC component is ionized (the imide bond is broken by the frictional heat during rubbing and the moisture in the air in the alignment film that has re-attached by rubbing, and the carboxylic acid in the alignment film is converted into ions by the DC electric field. Easier to separate)
And then begin to diffuse into the liquid crystal. These ions increase in density with the driving time of the liquid crystal image display device, and eventually the picture element portion 9.
It spreads to the area of. The specific resistance of the liquid crystal is significantly reduced by the ions, so that the voltage holding ratio of the liquid crystal is deteriorated (the specific resistance of the liquid crystal is reduced, so that the image signal applied to the liquid crystal is not held until the next image signal is applied. However, as shown in FIG. 7, a region where the image quality of the liquid crystal image display device is poor (the region 30 where the voltage holding ratio of the liquid crystal is deteriorated) is generated near the rubbing start point of the active substrate 1 having a high ion concentration. Was.

Accordingly, the present invention prevents a large amount of foreign matter adhered by rubbing on a scanning line near the rubbing start point on the active substrate side from being ionized by a DC component and diffused into the liquid crystal, thereby preventing the voltage holding ratio of the liquid crystal from lowering. Things.

[0012]

In order to solve the above-mentioned problems, the present invention has a first aspect in which a plurality of scanning lines and signal lines are provided, and a switching element and a pixel electrode are provided for each unit pixel. A second substrate having a translucent insulating substrate and a transparent conductive counter electrode;
Liquid crystal image formed by filling liquid crystal between the translucent insulating substrate
In the method for manufacturing an image display device, a part of the scanning line of the first translucent insulating substrate is terminated in the picture element portion, and the terminated portion of the scanning line is set as a rubbing start point. Is what you do .

[0013]

The operation of this technical means is as follows. In other words, by terminating a plurality of scanning lines near the rubbing start point in the vicinity of the picture element, the adhesion of foreign matter due to rubbing spreads to the picture element portion, but the DC component due to the potential of the scanning line in the picture element portion is different from the counter electrode potential. It is almost adjusted to “0” by adjusting the signal line potential. Therefore, even if the liquid crystal image display device is continuously driven for a long time, the foreign matter adhered by rubbing is not ionized and the voltage holding ratio of the liquid crystal does not deteriorate.

[0014]

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

FIG. 1 shows an active matrix type liquid crystal image display device using a TN type liquid crystal material used in this embodiment. The liquid crystal image display device was obtained by bonding the active substrate 1 and the counter electrode substrate 7 with a sealing material 8 and enclosing a TN type liquid crystal therein. The picture element section 9 has a size of 1 inch in the diagonal direction, and the total number of the scanning lines 2 is 220 and the total number of the signal lines 4 and 4 'is 35
The total number of picture elements was 77440. Amorphous silicon was used for the semiconductor of the switching element. The transmission of the driving signal to the liquid crystal image display device is based on a polyimide-based resin thin film for transmitting an external driving signal to the scanning line mounting terminal 5 and the signal line mounting terminal 6, and is a terminal of gold-plated copper foil. A mounting method in which connection films having groups (not shown) were pressed with an adhesive was used. The orientation of the liquid crystal is determined by rubbing the surface of the active substrate 1 and the counter electrode substrate 7 with a polyimide-based organic material in a thin film shape on a surface of the active substrate 1 and the counter electrode substrate 7 in contact with the liquid crystal a plurality of times (rubbing). went. Note that the crossing angle between the rubbing direction a of the active substrate and the rubbing direction b of the counter electrode substrate was substantially 90 degrees. Further, in the present embodiment, unlike the prior art, the scanning line on the rubbing start point side of the active substrate and the counter electrode substrate is terminated at the switching element portion of the picture element portion 9. The termination state is as shown in the main plan view of one picture element in FIG.

Next, the operation of the configuration of this embodiment will be described. In the liquid crystal image display device prepared in this manner, foreign matter adhering to the rubbing of the picture element portion 9 is prevented because no scanning line is arranged in the area where the liquid crystal is filled except for the pixel portion 9 near the rubbing start point. Attached inside.
However, the foreign matter adhering to the inside of the picture element portion 9 has a small size on the order of a microscope, so that there is no practical problem. Since the DC component applied to the liquid crystal is adjusted to almost “0” by adjusting the potential of the electrode and the driving potential of the scanning line, the voltage holding ratio of the liquid crystal due to ionization by the DC component of the adhered foreign matter and diffusion to the liquid crystal. Does not cause deterioration of

As a result, a liquid crystal image display device in which the image quality does not deteriorate due to the deterioration of the voltage holding ratio of the liquid crystal even when driven continuously for a long time was obtained. (Table 1) shows the liquid crystal image display of which the image quality was deteriorated due to the deterioration of the voltage holding ratio of the liquid crystal when the conventional and the liquid crystal image display devices of this embodiment were continuously driven in a constant temperature bath at 60 ° C. The result of the incidence rate according to the driving time of an apparatus is shown.
The liquid crystal image device of the present embodiment has a
A result was obtained that the image quality did not deteriorate even after continuous driving for 00 hours.

[0018]

[Table 1]

Next, another embodiment of the present invention will be described. FIG. 3 shows another embodiment of the present invention. In this embodiment, half of the scanning lines 2 closest to the rubbing start point of the active substrate are terminated at the switching element section of the picture element section 9. In the liquid crystal image display device of this embodiment, the same result as that shown in (Table 1) was obtained from the same operation as the embodiment shown in FIG.

[0020]

As described above, according to the present invention, by terminating at least a plurality of scanning lines near the rubbing start point at the picture element portion, foreign matter due to rubbing to a region where a DC component is applied to the liquid crystal is obtained. Adhesion is prevented, and the attached foreign substances are ionized by the DC component of the scanning line potential and diffused into the liquid crystal during long-time continuous driving of the liquid crystal image display device, thereby preventing deterioration of the image quality due to deterioration of the voltage holding ratio of the liquid crystal. Things.

As an embodiment of the present invention, an active matrix type liquid crystal image display device using a TN type liquid crystal material and using amorphous silicon as a semiconductor of a switching element has been described. The effect of the active matrix type liquid crystal image device described above is not impaired.

[Brief description of the drawings]

FIG. 1 is a main configuration diagram of a liquid crystal image display device according to an embodiment of the present invention.

FIG. 2 is a main plan view of one picture element showing a termination state of a scanning line at a picture element portion.

FIG. 3 is a main configuration diagram of a liquid crystal image display device according to another embodiment of the present invention.

FIG. 4 is a main configuration diagram of a conventional liquid crystal image display device.

FIG. 5 is a main sectional view of one picture element of the liquid crystal image display device.

FIG. 6 is a waveform chart showing a driving potential of one picture element of the liquid crystal image display device.

FIG. 7 is a schematic diagram illustrating a region where a voltage holding ratio of liquid crystal is deteriorated when the liquid crystal image display device is driven for a long time.

FIG. 8 is a schematic view showing a distribution state of foreign matter adhered by rubbing.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 active substrate 2, 3 scanning line 4, 4 'signal line 7 counter electrode substrate 9 picture element portion 5a rubbing direction of active substrate 5b rubbing direction of counter electrode substrate

Continuation of the front page (72) Inventor Yasushi Yasushige 1006 Kazuma Kadoma, Kadoma City, Osaka Inside Matsushita Electric Industrial Co., Ltd. (56) References JP-A-63-116190 (JP, A)

Claims (3)

(57) [Claims] 1. A first light-transmitting insulating substrate having a plurality of scanning lines and signal lines, having a switching element and a pixel electrode for each unit pixel, and a transparent conductive counter electrode. liquid crystal formed by filling a liquid crystal between the second transparent insulating substrate having
In the image display device , a liquid is characterized in that a part of a scanning line of the first translucent insulating substrate is terminated in a pixel portion, and the terminated portion of the scanning line is set as a rubbing start point.
Of manufacturing a crystal image display device . 2. A method for manufacturing a liquid crystal is a TN type liquid crystal image display apparatus according to claim 1, wherein the liquid crystal. 3. The method for producing a liquid crystal image display apparatus according to claim 2, wherein the switching element is a thin film transistor having an amorphous silicon semiconductor layer.