JPH08278510A - Matrix type liquid crystal display device - Google Patents

Abstract

PURPOSE: To obviate the occurrence chipping in metallic light shielding films,and to obtain high reliability even in a high-temp. and high-humidity environment by forming patterns for thickness compensation of a thickness approximately equal to the thickness of signal wirings at the ends of substrates. CONSTITUTION: Gate lines 34 are formed to extend from one end side of the lower substrate 33 connected to the driving circuit elements of TFTs 36 to pixel electrodes 37 on the other end side. The patterns 56 for thickness compensation are formed at the other ends of the lower substrate 33 in order to suppress a change in the thickness of sealing materials 49 occurring in a difference as to whether the gate lines 34 are formed or not between the other end side of the lower substrate 33 formed with the injection ports of the sealing materials 49 and the one end side facing driving circuit elements. The patterns 56 for thickness compensation are formed at approximately the same thickness as the thickness of the gate lines 34 by the same stage as for the gate lines 34. As a result, the upper substrate 32 and the lower substrate 33 are held parallel with each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a matrix type liquid crystal display device which is preferably implemented in an in-vehicle image display device or the like and used in a bad environment of high temperature and high humidity.

[0002]

2. Description of the Related Art FIG. 4 is a sectional view of a part of a typical prior art liquid crystal display device 1, and FIG. 5 is a plan view showing a state in which an upper substrate 2 is removed. In addition, in FIG.
The cross section of is indicated by reference numeral AA.

This liquid crystal display device 1 has a thin film transistor (TFT).
(m Transistor) is an active matrix type liquid crystal display device using an active element. Therefore, on the lower substrate 3, a plurality of gate lines 4 and source lines 5 are electrically insulated from each other and arranged orthogonally.
At each intersection of the gate line 4 and the source line 5,
The TFT 6 is formed and each gate line 4
Pixel electrodes 7 to which a drive voltage is applied by the corresponding TFTs 6 are individually formed in a region surrounded by the source line 5 and the pixel electrodes 7 are arranged in a matrix.

The upper substrate 2 and the lower substrate 3 are made of a transparent material such as glass and are arranged in parallel with each other. An analyzer 8 is attached to the surface of the upper substrate 2 opposite to the lower substrate 3, and a polarizer 9 is similarly attached to the surface of the lower substrate 3 opposite to the upper substrate 2. There is.
The analyzer 8 and the polarizer 9 have their polarization planes 90 ° to each other.
They are arranged so that they are offset from each other, that is, they are orthogonal to each other.

A metal light-shielding film 10, a color filter 11, a transparent conductive film 12, and an alignment film 13 are laminated in this order on the surface of the upper substrate 2 on the lower substrate 3 side. . On the other hand, on the surface of the lower substrate 3 on the upper substrate 2 side, the protective film 14, the gate line 4, the insulating film 15, the gate insulating film 16, the TFT 6, the source line 5, and the pixel. The electrode 7, the protective film 17, and the alignment film 18 are laminated in this order.

The upper substrate 2 and the lower substrate 3 are hermetically joined to each other at their outer peripheral edge portions by a sealing material 19. Further, between the upper substrate 2 and the lower substrate 3, the upper substrate 2
Further, spacers 20 for keeping the interval constant are scattered over the entire surface of the lower substrate 3. The sealing material 19 has an injection port 21 formed therein.
After the liquid crystal 22 is injected from the injection port 21, the injection port 21 is
It is sealed by 3.

A drive circuit element 24 for outputting a scanning signal to the gate line 4 is connected to one end of the lower substrate 3 in the gate line 4 direction. A voltage corresponding to the video signal level is derived from the source line 5 at one end or both ends of the lower substrate 3 in the source line 5 direction. Therefore, the voltage of the level corresponding to the image to be displayed is applied to the corresponding pixel electrode 7 via the TFT 6 selected by the gate line 4 and the source line 5. The alignment direction of the liquid crystal 22 changes according to the voltage, and the light from the backlight light source arranged on the lower substrate 3 side has its transmittance changed and is emitted from the upper substrate 2 side. It becomes possible to display.

[0008]

As described above, in the matrix type liquid crystal display device 1, the gate line 4 is formed from one end of the lower substrate 3 connected to the drive circuit element 24 toward the other end. ing. On the other hand, when the liquid crystal display device 1 is used in a bad environment of high temperature and high humidity such as a vehicle interior, water may enter the panel from the sealing material 23 having the weakest moisture resistance.

When the moisture penetrates in this way, the penetrated moisture causes an electrochemical reaction due to the voltage applied between the transparent electrode 12 of the upper substrate 2 and the gate line 4 to form the metal light-shielding film 10. The metal atoms that have been formed are eluted as cations in the liquid crystal 22. Therefore,
It is said that the metal light-shielding film 10 shown by the two-dot chain line and the diagonal line in FIG. 5 has a defect near the injection port 21 and causes a stain or unevenness in the display image, or a defect such as a disconnection in the gate line 4. There's a problem.

In order to solve such a problem, for example, as shown in Japanese Utility Model Application Laid-Open No. 61-38616, the electrode of a specific portion is removed to make use of the gate line 4.
It is conceivable that the pixel is formed up to the other end side pixel of the lower substrate 3, that is, the end side pixel, and the portion further extending to the other end of the lower substrate 3 is deleted. However, in the case of such a configuration, the seal material 19 formed by printing is formed on one end side of the lower substrate 3 on which the gate line 4 is formed and on the other end side on which the gate line 4 is not formed. There is a problem in that the thickness is different and the display quality is degraded such as the occurrence of interference fringes.

Therefore, as shown in the liquid crystal display device 30 of FIG. 6, it is necessary to apply the protective film 29, which increases the manufacturing cost and reduces the yield. If such measures are not taken, the usable environment of the liquid crystal display device 1 is limited, and it becomes difficult to apply the liquid crystal display device 1 to a wide range of applications.

An object of the present invention is to provide a matrix type liquid crystal display device which can obtain high reliability without causing a defect in the metal light shielding film even in a bad environment of high temperature and high humidity. is there.

[0013]

According to another aspect of the present invention, there is provided a matrix type liquid crystal display device comprising a pair of front and rear substrates parallel to each other, and pixel electrodes arranged in a matrix on the substrate.
A drive circuit element mounted on one end of the substrate and for driving the pixel electrode, and a signal formed on the substrate from the one end to the pixel electrode on the other end side so as to be connected to the drive circuit element. In the wiring and the board on the front side,
A metal light-shielding film formed so as to open at least a region corresponding to the pixel electrode, and a sealing material that hermetically joins the outer peripheral edge portions of the substrate and forms a liquid crystal injection port on the other end side. A sealing material that seals the injection port, and a thickness that is formed in the same step as the signal wiring and is separated from the signal wiring at the other end of the substrate, and has a thickness approximately equal to the thickness of the signal wiring. And a compensation pattern.

In the matrix type liquid crystal display device according to a second aspect of the present invention, in the thickness compensating pattern, the signal wiring extending to the other end of the substrate is divided near the pixel electrode on the other end side. It is formed.

[0015]

According to the first aspect of the present invention, the outer peripheral edge portions of the pair of front and rear substrates which are parallel to each other are airtightly joined by the sealing material, and the injection port formed in the sealing material in the space thus formed. After the liquid crystal is injected from, the injection port is sealed with a sealing material, and the pixel electrodes are arranged in a matrix on the substrate, and the pixel electrodes are connected to one end of the substrate by a driving circuit element. In a matrix type liquid crystal display device in which a driving voltage is applied via a signal wiring, the signal wiring is formed from one end of a substrate on which a driving circuit element is mounted to a pixel electrode on the other end side, and In order to compensate for the difference in thickness between the one end side and the other end side of the substrate of the sealing material, the seal member should be separated from the signal wiring and in the same step as the signal wiring, at the other end of the substrate. About the thickness of the signal wiring Correct form the thickness compensation pattern thickness.

Therefore, even if moisture enters from the inlet, no signal wiring to which a voltage is applied is formed in the vicinity of the inlet, and at least the front side substrate is formed by the electrochemical reaction of the moisture. It is possible to prevent the occurrence of a defect in which the metal light-shielding film formed so as to open the region corresponding to the pixel electrode is lost, and it is possible to improve reliability.

With this, it is not necessary to form a protective film or the like for preventing the defects in relation to the metal light-shielding film, so that the cost can be reduced and the yield can be improved. In addition, the environment in which the liquid crystal display device can be used is widened, and the liquid crystal display device can be used for a wide range of purposes.

According to the invention of claim 2, the thickness compensating pattern is formed by extending the signal wiring, that is, the signal wiring formed up to the pixel electrode on the other end side of the substrate is further formed on the substrate. It is formed so as to be divided in the vicinity of the pixel electrode when extending toward the other end. Therefore, it is possible to prevent the metal light-shielding film from being damaged by simply using the conventional signal wiring forming process and devising the patterning of the signal wiring.

[0019]

EXAMPLE An example of the present invention will be described below with reference to FIGS.

FIG. 1 shows a liquid crystal display device 3 according to an embodiment of the present invention.
1 is a sectional view of a part of FIG. 1, and FIG.
1 is a plan view with the upper substrate 32 of FIG. 1 removed, and FIG. 3 is a perspective view of FIG. 2. In FIG. 2, the cross section of FIG. 1 is indicated by reference numeral BB.

The liquid crystal display device 31 includes the upper substrate 3
Gate lines 34 and source lines 35 are electrically insulated from each other and orthogonally arranged on a lower substrate 33 facing 2 and TFTs 36 are formed at respective intersections of the gate lines 34 and source lines 35. This is a TFT active matrix type liquid crystal display device. Further, on the lower substrate 33, a TFT 36 corresponding to the substantially rectangular region surrounded by the gate line 34 and the source line 35 is provided.
The pixel electrode 37 to which the drive voltage is applied is formed.

On the surface opposite to the lower substrate 33 of the upper substrate 32, a film-shaped analyzer 38 is attached, and similarly, on the surface of the lower substrate 33 opposite to the upper substrate 32. Has a polarizer 39 attached. The analyzer 38 and the polarizer 39 have their polarization planes shifted from each other by 90 °,
That is, they are arranged orthogonally.

On the surface of the lower substrate 33 side of the upper substrate 32, a metal light shielding film 40, a color filter 41, a transparent conductive film 42, and an alignment film 43 are laminated in this order. Further, on the surface of the lower substrate 33 on the upper substrate 32 side, the protective film 44, the gate line 34, and the insulating film 4 are formed.
5, a gate insulating film 46, the TFT 36, the source line 35 and the pixel electrode 37, a protective film 47,
The alignment film 48 is laminated in this order.

The alignment films 43 and 48 define the alignment directions of the liquid crystals in parallel with the polarization planes of the analyzer 38 and the polarizer 39, respectively. Therefore,
The orientation of the cloth for rubbing the alignment film 43 formed on the upper substrate 32 and the orientation of rotation of the cloth for rubbing the orientation film 48 formed on the lower substrate 33 are set to 9
The upper substrate 32 and the lower substrate 33 are loaded into a processing machine to be subjected to a rubbing process so that a shift of 0 ° occurs.

The outer peripheral edges of the upper substrate 32 and the lower substrate 33 are airtightly joined by a seal material 49, and the spacers 50 scattered between the two substrates cover the entire surfaces of the substrates 32, 33. Are held parallel to each other.

An injection port 51 is formed in the sealing material 49, and after the liquid crystal 52 is injected into the injection port 51,
It is hermetically sealed by the sealing material 53. The liquid crystal 52
Corresponds to the analyzer 38 and the polarizer 39,
It is a TN liquid crystal material in which a twisted liquid crystal material is added as a chiral material to a nematic liquid crystal material, and the alignment direction of liquid crystal molecules is twisted by 90 ° on the alignment film 43 side and the alignment film 48 side. It has a different structure.

A drive circuit element 54 for outputting a scanning signal for ON / OFF driving the TFT 36 to the gate line 34 is connected to one end portion in the direction of the gate line 34 on the outer peripheral edge of the lower substrate 33. It On the contrary,
A driving circuit element 55 for deriving a voltage to be applied to the pixel electrode 37 via the source line 35 at one end or both ends in the source line 35 direction of the lower substrate 34 in accordance with the video signal level. Are connected.

Therefore, via the TFT 36 selected by the gate line 34 and the source line 35,
A voltage of a level corresponding to the image to be displayed is applied to the corresponding pixel electrode 37. The alignment direction of the liquid crystal 52 changes according to the voltage, and the light from the backlight light source arranged on the lower substrate 33 side has its transmittance changed and is emitted from the upper substrate 32 side. It becomes possible to display.

The liquid crystal display device 31 constructed as described above
In the present invention, the gate line 34 is formed to extend from one end side of the lower substrate 33 connected to the drive circuit element 54 to the pixel electrode 37 on the other end side, that is, near the pixel on the end side. There is. Therefore, in the sealing material 49 formed by thick film printing or the like, the gate line 34 is formed on the other end side of the lower substrate 33 where the injection port 51 is formed and on the one end side facing the drive circuit element 54. A thickness compensating pattern 56 is formed on the other end of the lower substrate 33 in order to suppress the change in the thickness of the sealing material 49 due to the difference in whether or not the lower substrate 33 is formed. This makes it possible to hold the upper substrate 32 and the lower substrate 33 in parallel with each other.

The manufacturing process of the liquid crystal display device 31 as described above will be described in detail below. First, on the upper substrate 32 side, a metal light-shielding film 40 is uniformly laminated and formed by sputtering on the surface which becomes the lower substrate 33 side, and after patterning is performed using a photolithography technique according to a desired pattern, The pixel electrode 3 that has been subjected to etching treatment
The portion corresponding to 7 corresponding to the opening is removed and cleaning is performed. In FIG. 2, the portion of the metal light-shielding film 40 remaining after the etching process is shown by the alternate long and two short dashes line and the diagonal line.

Next, a photoresist colored red by the pigment dispersion method is applied to one surface, patterned by the photolithography technique, and washed. Similarly, the photoresists colored in blue and green are also patterned to form the color filter 41.

Subsequently, a transparent conductive film 42 to be a common electrode is formed by sputtering, followed by cleaning and baking, and then an alignment film 43 is formed on the transparent conductive film 42 by a printing method, followed by baking. Then, the rubbing process is performed to form grooves for aligning liquid crystal molecules, and the grooves are washed.

Further, after the sealing material 49 is formed by the thick film printing method, it is fired. A granular spacer is mixed in the material of the sealing material 49 in order to make the film thickness of the sealing material 49 uniform. Then, the spacer 5
0 is sprinkled to complete the upper substrate 32.

On the other hand, the upper substrate 3 of the lower substrate 33
First, the protective film 44 is uniformly formed on the surface on the second side by sputtering. Next, the gate line 34
The thin metal film formed by sputtering is patterned by photolithography, etching and cleaning. At this time, in the present invention, at the same time, the thickness compensation pattern 56 is formed. Subsequently, the patterned gate line 34 and the thickness compensation pattern 56 are formed.
By anodizing the gate lines 34
And the insulating film 45 is formed on the thickness compensation pattern 56.

When the gate line 34 and the thickness compensating pattern 56 are completed, the gate insulating film 46 is formed by a series of steps of sputtering, photolithography, etching and cleaning. On top of that, the semiconductor layer 61
An amorphous silicon layer to be formed is formed by a plasma CVD method, and is patterned by performing photolithography, etching and cleaning. Then, the source line 35 and the drain electrode 62 are sputtered,
Patterned by photolithography, etching and cleaning. In this way, the TFT 36 is completed.

Further, a protective film 47 is formed on the plasma CV.
It is formed by the steps of D, photolithography, etching and cleaning. Further, after the alignment film 48 is formed and baked by the printing method, the rubbing process and the cleaning are further performed to complete the lower substrate 33. The lower substrate 33 and the upper substrate 32 are combined with each other and subjected to heat and pressure treatment, and the sealing material 49 is hardened and bonded, and then cut into a panel of a desired size.

After the liquid crystal 52 is injected from the injection port 51 into each of the divided panels, the sealing material 53 made of an ultraviolet curable resin is permeated into the injection port 51 and is irradiated with ultraviolet rays to seal the sealing. The liquid crystal 52 is sealed in the panel by hardening the stopper 53. Subsequently, the analyzer 38 is attached on the upper substrate 32, and the polarizer 39 is attached on the lower substrate 33. Then, the drive circuit elements 54, 5 are formed on the lower substrate 33.
5 is mounted, or the film substrate on which the drive circuit elements 54 and 55 are mounted is connected to the lower substrate 33, whereby the liquid crystal display device 31 is completed.

In the liquid crystal display device 31 according to the present invention configured as described above, even if water enters through the injection port 51 having weak moisture resistance, there is no electrode to which a voltage is applied near the injection port 51. Therefore, it is possible to prevent the loss of the metal light-shielding film 40 due to the electrochemical reaction as described in the section of the related art, and it is possible to improve the reliability.

As for the thickness of the sealing material 49, by forming the thickness compensating pattern 56, the other end side of the lower substrate 33 on which the thickness compensating pattern 56 is formed and the gate line 34 are formed. It can be made equal to the one end. Therefore, the upper substrate 32 and the lower substrate 33
The gap between the liquid crystal cells, that is, the gap between the liquid crystal cells can be kept constant, and the metal light-shielding film 40 is deficient as described above without deteriorating the display quality such as the generation of interference fringes due to the change in the cell gap. Can be prevented. Furthermore, the thickness compensating pattern 56 can be formed in the same step as the gate line 34 by changing the mask used when the gate line 34 is formed, and the cost is not increased. .

Therefore, the metal light-shielding film 40 is not subjected to any special processing such as providing a protective film.
The loss of 0 can be prevented, and the cost can be reduced and the yield can be improved. Further, the liquid crystal display device 31 can be used in a bad environment of high temperature and high humidity, and the use of the liquid crystal display device 31 can be expanded to a wide range.

Although the above-described embodiment is a TFT active matrix type liquid crystal display device, as another embodiment of the present invention, a MIM (Metal Insulator Metal) is provided.
It may be a matrix type liquid crystal display device having other structure such as a liquid crystal display device of the type. Although the thickness compensating pattern 56 is formed as an extension of the gate line 34 in the above-described embodiment, it is formed in another pattern such as a dot having the same thickness as the gate line 34 as another embodiment of the present invention. May be done. Furthermore, the drive circuit element 55
Is provided only on one end side of the lower substrate 33 in the source line 35 direction and the injection port is formed on the other end side, the source line 35 is similarly divided to form a thickness compensation pattern. May be.

[0042]

As described above, in the matrix type liquid crystal display device according to the first aspect of the present invention, the signal wiring extending from one end of the substrate is formed up to the pixel electrode on the other end, which corresponds to this. A thickness compensating pattern having a thickness substantially equal to the thickness of the signal wiring is formed on the other end of the substrate in the same step as the signal wiring.

Therefore, a change in the thickness of the sealing material that causes deterioration of the display quality is suppressed, and an inlet having weak moisture resistance is formed on the other end side of the sealing material, and moisture enters from the inlet. However, there is no electrode to which a drive voltage is applied on the other end side, and it is possible to prevent the metal light-shielding film from being damaged due to the electrochemical reaction of the moisture, thereby improving the reliability.

As a result, no special treatment such as covering the metal light-shielding film with a protective film is required, and the cost can be reduced and the yield can be improved. In addition, the liquid crystal display device can be used for a wide range of purposes.

In the matrix type liquid crystal display device according to the second aspect of the present invention, the thickness compensating pattern is formed by dividing the signal wiring extending to the other end of the substrate as described above.

Therefore, the defect of the metal light-shielding film as described above can be prevented only by changing the mask used for processing the signal wiring.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view of a liquid crystal display device according to an embodiment of the present invention.

FIG. 2 is a plan view of the liquid crystal display device shown in FIG. 1 with an upper substrate removed.

FIG. 3 is a perspective view of FIG. 2;

FIG. 4 is a cross-sectional view of a portion of a typical prior art liquid crystal display device.

5 is a plan view of the liquid crystal display device shown in FIG. 4 with an upper substrate removed.

6 is a cross-sectional view showing a part of another conventional liquid crystal display device for overcoming the problems occurring in the liquid crystal display device shown in FIG.

[Explanation of symbols]

 31 liquid crystal display device 32 upper substrate 33 lower substrate 34 gate line (signal wiring) 35 source line 36 TFT 37 pixel electrode 40 metal light-shielding film 49 sealing material 51 injection port 52 liquid crystal 53 sealing material 54 driving circuit element 55 driving circuit element 56 Thickness compensation pattern

Claims (2)

[Claims] 1. A pair of front and rear substrates parallel to each other, pixel electrodes arranged in a matrix on the substrate, a drive circuit element attached to one end of the substrate for driving the pixel electrode, and the substrate. Above, to connect to the drive circuit element,
Signal wiring formed from the one end to the pixel electrode on the other end side, a metal light-shielding film formed on the front side substrate so as to open at least a region corresponding to the pixel electrode, and an outer peripheral edge of the substrate A sealing material that airtightly joins the parts, and a liquid crystal injection port is formed on the other end side, a sealing material that seals the injection port, and the other end of the substrate separated from the signal wiring. A matrix type liquid crystal display device comprising: a thickness compensation pattern formed in the same step as the signal wiring and having a thickness substantially equal to the thickness of the signal wiring. 2. The thickness compensating pattern is formed by dividing a signal wiring extending to the other end of the substrate in the vicinity of the pixel electrode on the other end side. Matrix type liquid crystal display device.