JPH08160444A - Liquid crystal display device - Google Patents

Abstract

PURPOSE: To reduce wiring resistances of connection lines connecting scanning and signal electrodes of a liquid crystal panel to driving parts impressing driving voltages on these electrodes and variations of them. CONSTITUTION: In a liquid crystal display device having plural scanning electrodes 4, plural signal electrodes 5, voltage driving parts 15 for scanning electrodes impressing driving voltages on plural scanning electrodes 4 and voltage driving parts 12 for signal electrodes impressing driving voltages on plural signal electrodes 5 in a liquid crystal panel 1, leader lines 13 for scanning electrodes in which auxiliary material lines 14 for scanning electrodes consisting of material whose specific resistance is much smaller than that of connection lines are formed in the inside of the connection lines connecting plural scanning electrodes 4 and respective electrodes of voltage driving parts 15 and consisting of the same material as that of scanning electrodes and leading lines for signal electrodes 10 in which auxiliary lines 11 for signal electrodes consisting of material whose specific resistance is much smaller than that of connection lines are formed in the inside of the connection lines connecting plural signal electrodes and respective electrodes of voltage driving parts 12 for signal electrodes and consisting of the same material as that of signal electrodes are provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device for connecting a scanning and signal electrodes of a liquid crystal panel and a driving section for applying a driving voltage to them, and more particularly, the present invention relates to a wiring resistance of a connecting line which causes a display failure. Also, the present invention relates to a liquid crystal display device capable of reducing the variation.

[0002]

2. Description of the Related Art FIG. 8 is a plan view showing a conventional liquid crystal display device, FIG. 9 (a) is a sectional view taken along a sectional line X1-X1 in FIG. 8, and FIG. 9 (b) is a sectional line. 9 is a sectional view taken along line X2-X2 in FIG. 8. FIG. As shown in FIGS. 8 and 9, in a conventional liquid crystal display device, a scanning panel 1 is provided with a scanning electrode transparent substrate 2 and a signal electrode transparent substrate 3. On the inner surface of the scanning electrode transparent substrate 2, a scanning electrode 4 is formed in which a plurality of transparent electrode lines made of indium oxide are arranged. On the inner surface of the signal electrode transparent substrate 3,
A signal electrode 5 is formed by arranging similar transparent electrode lines. On the inner surfaces of the scanning electrode 4 and the signal electrode 5, alignment films 6 and 7 of a polymer film subjected to alignment treatment for aligning liquid crystal molecules in parallel with the substrate are arranged. Further, a ferroelectric liquid crystal is injected between both substrates 2 and 3 corresponding to the display area. A seal portion 9 that surrounds the display area is provided around the display area. Further, the scanning electrode voltage driving unit 15 shown in FIG. 9 and the signal electrode voltage driving unit 12 shown in FIG. 8 are provided. In order to electrically connect the scan electrodes 4 to the scan electrode voltage driving unit 15, scan electrode lead lines 13 made of indium oxide are formed in the non-display area of the scan electrode transparent substrate 2. Regarding the signal electrode 5 as well, in order to electrically connect the signal electrode 5 to the signal electrode voltage driving unit 12, a signal electrode lead wire 10 made of indium oxide is formed in the non-display area of the signal electrode transparent substrate 3. There is.

In the liquid crystal display device having such a structure, a portion where each scanning electrode 4 and the signal electrode 5 intersect constitutes one display pixel, and the pixels are arranged in a matrix. Each pixel is turned on by applying a voltage to the corresponding scanning electrode 4 and signal electrode 5, and is turned off when no voltage is applied to both pixels.

[0004]

FIG. 10 is a diagram for explaining the wiring lengths of the lead lines 13 for scanning electrodes and the lead lines 10 for signal electrodes. As shown in the figure, each scanning electrode 4 of the liquid crystal panel 1 and each electrode 4 ′ of the scanning electrode voltage driving unit 15
Are arranged so as to face each other and the width between the scanning electrodes 4 is smaller than the width between the electrodes 4 ′, so that the scanning electrode lead-out line 13 connecting between the scanning electrodes 4 and the electrodes 4 ′ is partially If it sees, it consists of a straight part and a bent part to this, and each has a different length. Similarly, the signal electrodes 5 of the liquid crystal panel 1 and the electrodes 5 ′ of the signal electrode voltage driver 12 are arranged so as to face each other, and the width between the signal electrodes 5 is smaller than the width between the electrodes 5 ′. Each of the signal electrode lead wires 10 connecting the signal electrode 5 and the electrode 5 ′ is, when viewed partially, composed of a straight line portion and a bent portion corresponding to the straight line portion, and have different lengths. Therefore, the wiring resistance value of each electrode of the scanning electrode lead wire 13 and the signal electrode lead wire 10 is relatively large, and the difference (variation) between the respective wiring resistance values is also large. As a result, here, the increase in voltage drop due to the wiring resistance itself,
In addition, there is a problem that the display quality is deteriorated due to the variation in the voltage drop between the lines due to the variation in the wiring resistance. Furthermore, there is a problem that a difference (variation) in the applied voltage occurs between the electrodes due to a difference (variation) in the resistance value of each lead wire. As a result, the top and bottom of the screen,
Contrast unevenness appears in the left-right direction, leading to deterioration in display quality.

[0005]

In order to solve the above problems, the present invention provides a liquid crystal display device having the following constitution. That is, a plurality of scan electrodes, a plurality of signal electrodes on a liquid crystal panel, a scan electrode voltage driver for applying a drive voltage to the plurality of scan electrodes, and a drive voltage for a signal electrode on the plurality of signal electrodes. A liquid crystal display device having
Inside the connection line that connects each of the plurality of scan electrodes and each electrode of the scan electrode voltage driving unit and is made of the same material as the scan electrode, a scan made of a material having a resistance much smaller than the specific resistance of the connection line. This connection is made inside the connecting line made of the same material as the signal electrode, which connects the scanning electrode lead line formed with the electrode auxiliary line and each of the plurality of signal electrodes and each electrode of the signal electrode voltage driving unit. There is provided a signal electrode lead wire formed with a signal electrode auxiliary wire made of a material having a much smaller specific resistance than the wire.

In this case, the scanning electrode lead-out line and the signal electrode leading-out line use indium oxide as their connecting line and aluminum as the scanning electrode auxiliary line and the signal electrode auxiliary line. May be.
Further, the resistance values of the scanning electrode lead lines and the signal electrode lead lines are adjusted by changing the wiring width, wiring length, and film thickness of the scanning electrode auxiliary line and the signal electrode auxiliary line. May be.

[0007]

According to the liquid crystal display device of the present invention, each of the plurality of scan electrodes and each electrode of the scan electrode voltage driving unit is connected to the inside of a connection line made of the same material as the scan electrode. Even if each resistance value is very small and there is a difference (variation) in each wiring length, the scanning electrode lead wire formed with the scanning electrode auxiliary line made of a material much smaller than the specific resistance of the line, The difference (variation) in each resistance value is considerably reduced. Furthermore, each of the plurality of signal electrodes and each electrode of the signal electrode voltage driving unit is connected to the inside of a connecting wire made of the same material as the signal electrode, and made of a material having a resistance much smaller than the specific resistance of the connecting wire. The resistance value of the signal electrode lead-out line formed with the signal electrode auxiliary line is extremely small, and even if there is a difference (variation) in each wiring length, the difference (variation) in each resistance value is significantly reduced. . Therefore, since the voltage drop due to the wiring resistance itself can be reduced, the generated voltage of each voltage driving unit can be applied to all the electrodes as it is. Furthermore, since the variation in voltage drop is reduced, it is possible to prevent a difference in applied voltage between electrodes. As a result, there is no unevenness in contrast in the vertical and horizontal directions of the screen, and the display quality can be improved. Further, since the wiring resistance value can be reduced, the output voltage and the output current of the scan electrode voltage drive unit and the signal electrode voltage drive unit are reduced,
The scan electrode voltage driver and the signal electrode voltage driver can be downsized. In this case, the scan electrode lead line and the signal electrode lead line use indium oxide as their connecting line, aluminum as the scan electrode auxiliary line and signal electrode auxiliary line, and the scan electrode lead line. The resistance value of the lead wire and the lead wire for the signal electrode is the wiring width of the scan electrode auxiliary line, the signal electrode auxiliary line,
By changing and adjusting the wiring length and the film thickness, the variation in the resistance value can be reduced to about 4% as compared with the previous one.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a plan view showing a liquid crystal display device according to the present invention, and FIG. 2 (a) is a cross-sectional view of the liquid crystal display device according to an embodiment of the present invention as seen from a section line X3-X3 in FIG.
FIG. 2B shows a liquid crystal display device according to an embodiment of the present invention.
FIG. 9 is a cross-sectional view taken along section line X4-X4 of FIG. 1 and 2
As shown in FIG. 3, the scanning panel 1 of the liquid crystal display device is provided with the transparent substrate 2 for scanning electrodes and the transparent substrate 3 for signal electrodes. On the inner surface of the scanning electrode transparent substrate 2, a scanning electrode 4 having a plurality of indium oxide transparent electrode lines arranged therein is formed. On the inner surface of the transparent substrate 3 for signal electrodes, the signal electrodes 5 in which similar transparent electrode lines are arranged are formed. On the inner surfaces of the scanning electrode 4 and the signal electrode 5, polymer alignment films 6 and 7 which are subjected to alignment treatment for aligning liquid crystal molecules in parallel with the substrate are arranged. Further, the ferroelectric liquid crystal 8 is injected between the substrates 2 and 3 corresponding to the display area. Further, a seal portion 9 that surrounds the periphery of the display area is provided. Further, the scanning electrode voltage driving unit 15 of FIG. 3 and the signal electrode voltage driving unit 12 of FIG. 5 are provided. In order to electrically connect the scan electrodes 4 and the scan electrode voltage driver 15, in the non-display area of the scan electrode transparent substrate 2, the scan electrode auxiliary lines 14 made of aluminum and the scan electrode drawers made of indium oxide are formed. Line 13 is formed. Regarding the signal electrode 5 as well, in order to electrically connect the signal electrode 5 and the signal electrode voltage driving unit 12, in the non-display area of the signal electrode transparent substrate 3, the signal electrode auxiliary line 11 made of aluminum and indium oxide are formed. The lead wire 10 for the signal electrode is formed.

FIG. 3 shows the lead-out line 1 for the scanning electrode of FIG.
FIG. 3 is a cross-sectional view of the portion of FIG. 3 taken along line X6-X6 and X5-X5 of the signal electrode lead wire 10 of FIG. 2B. As shown in FIG. 3, a scan electrode auxiliary line 14 made of aluminum is formed in a non-display area on the inner surface of the scan electrode transparent substrate 2, and a scan electrode lead line made of indium oxide is formed thereon. The line 13 is arranged.
At this time, as shown in FIG. 3, the scan electrode lead-out line 13 is formed so as to completely cover the scan electrode auxiliary line 14. Similarly for the signal electrode lead-out line 10, as shown in FIG. 4, a signal electrode auxiliary line 11 made of aluminum is formed in a non-display area on the inner surface of the signal electrode transparent substrate 3, and is formed thereon. A lead wire 10 for a signal electrode made of indium oxide is arranged in the. At this time, as shown in FIG. 4, the signal electrode lead wire 10 is formed so as to completely cover the signal electrode auxiliary wire 11.

In the liquid crystal display device having such a structure,
A portion where each scanning electrode 4 and the signal electrode 5 intersect constitutes one display pixel, and the pixel is arranged in a matrix.
Then, each pixel is turned on by applying a voltage to the corresponding scanning electrode 4 and signal electrode 5,
When there is no voltage applied to both, it turns off. In the present embodiment, the scan electrode voltage driver 15 and each scan electrode 4 are provided.
To substantially reduce the resistance value of the wiring resistance of the scanning electrode lead wire 13 and the wiring resistance of the signal electrode voltage driving section 12 and the signal electrode lead wire 10 reaching the signal electrodes 5 and its variation. , The inside of the scanning electrode lead wire 13 made of indium oxide has a specific resistance of 3 × 10 ⁻⁶ Ω.
A scan electrode auxiliary line 14 made of aluminum is formed. Similarly, a signal electrode auxiliary line 11 made of aluminum is formed inside the signal electrode lead line 10 made of indium oxide. Specific resistance is 3 × 10 ^-6 Ω
The wiring resistance of the lead wire 13 for the scanning electrode and the lead wire 10 for the signal electrode, which is made of only indium oxide and has a conventional specific resistance of 3 × 10 ⁻⁴ Ω · cm, by forming the auxiliary line made of aluminum of cm. On the other hand, its resistance value can be reduced and its variation can be reduced.
This change in resistance value may be set as follows.

FIG. 4 is a diagram showing the resistance value of each scan electrode lead line 13 and the resistance value of each scan electrode auxiliary line 14.
The wiring resistance of the scanning electrode lead wire 13 made of indium oxide is R0, the wiring resistance of the scanning electrode auxiliary line 14 made of aluminum is r0, and the resistance value of each scanning electrode lead wire 13 is shown in FIG. As shown, R1, R2,
If the resistance values of R3, ..., Rn-1, Rn and the scanning electrode auxiliary line 14 are similarly r1, r2, r3, ..., rn-1, rn, then R1 >> r1, R2 >> r2, R3 >> r3, ..., Rn-1 >> rn-1, R
n >> rn Furthermore, the wiring resistance r0 of the scan electrode auxiliary line 14 made of aluminum may be set so that r1≈r2≈r3≈, ..., ≈rn−1≈rn, and thereby,
The combined resistance Rn 'of the scanning electrode lead-out line 13 is Rn' = (Rn * r0) / (Rn + r0), and from Rn >> r0, Rn'≈r0. As described above, since the combined resistance Rn ′ of the lead-out lines 13 for each scanning electrode becomes as small as r0, it is possible to simultaneously reduce the variation in the resistance value of each wiring, for example, as follows.

FIG. 5 is a diagram for explaining the wiring resistance of the lead lines 13 for various scanning electrodes. As shown in this figure (a), a lead wire 13 ″ for a scanning electrode, which is made of indium oxide and has a wiring length of 1 cm, a wiring width of 0.015 cm, and a film thickness of 1500 Å.
Has a wiring resistance value of 1.3 kΩ. Next, this figure (b)
, The wiring length is 1.5 cm and the wiring width is 0.015c.
The wiring resistance value of the lead wire 13 ″ for scanning electrode made of indium oxide having a thickness of m and a film thickness of 1500 Å is 2.0 kΩ. The difference between the wiring resistance values of the two is 700 ohms.
As shown in FIGS. 7C and 7D, the scanning electrode auxiliary line 14 is made of aluminum and has a wiring width of 0.011 cm and a film thickness of 500 Å (the wiring length is the same as each lead wire length).
When the wiring resistance value is 1.3 kΩ, the combined resistance value of the scan electrode lead wire 13 having a wiring resistance value of 1.3 kΩ is 51 Ω, and the other combined resistance value of the scan electrode lead wire 13 having a wiring resistance value of 2 kΩ is 77 Ω. And the difference in the wiring resistance between the two is 2
With 6Ω, the resistance variation is about 4% (26 /
It can be reduced to 700≈0.037).
The same applies to the signal electrode lead wire 10.

According to this embodiment, the wiring resistance values of the scan electrode lead-out lines 13 and the signal electrode lead-out lines 10 and their variations are substantially reduced, so that the scan electrode voltage driver 15 and the scan electrodes 4 are provided. Variations in the potential difference between the signal electrodes, the potential difference between the signal electrode voltage driving unit 12 and the signal electrode 5, and the potential difference between the lines are reduced. As a result, there is no difference in the contrast between the lines, and the contrast becomes equal in the vertical and horizontal directions, and the display quality can be remarkably improved. That is, it is possible to reduce the liquid crystal display defect, which is a conventional problem, particularly the luminance difference between the liquid crystal lines.

Further, since the wiring resistance values can be reduced, the output voltage and output current of the scan electrode voltage drive section 15 and the signal electrode voltage drive section 12 are reduced, and the scan electrode voltage drive section 15 and the signal are reduced. The electrode voltage drive unit 12 can be downsized. The present invention is not limited to the above embodiment. Lead wire for scan electrode 1 which is the gist of the present invention
3 (including the scanning electrode auxiliary line 14) and the signal electrode lead-out line 10 (including the signal electrode auxiliary line 11) and the resistance value of each lead-out line deviate from the difference. Various changes and improvements can be made within the range not to be performed, for example, as follows.

FIG. 6 shows the lead-out line 1 for the scanning electrode of FIG. 2 (a).
3 is a cross-sectional view of a modified example of the signal electrode lead-out wire 10 of FIG. 2B, taken along the line 3 of FIG. 3B, taken along section lines X6-X6 and X5-X5, respectively. First, as shown in FIG. 3, each scanning electrode auxiliary line 14 and each signal electrode auxiliary line 11 are formed on the inner surface of each transparent substrate 2 and 3, and each scanning electrode lead-out line 1 is formed thereon.
3, the lead lines 10 for the signal electrodes are arranged. As shown in FIG. 6, the auxiliary lines 14 for the scan electrodes, the auxiliary lines 11 for the signal electrodes are connected to the lead lines 13 for the scan electrodes, and the auxiliary lines for the signal electrodes. It can be changed so as to be arranged at the center of the leader line 10. Although aluminum is used for the scanning electrode auxiliary line 14 and the signal electrode auxiliary line 11, a conductive material having a lower resistivity than indium oxide may be used. Furthermore, since the resistance value of each scanning electrode auxiliary line 14 and each signal electrode auxiliary line 11 is changed, the wiring width, wiring length, and film thickness can be changed.

[0016]

As described above, according to the present invention, the plurality of scan electrodes and the respective electrodes of the scan electrode voltage driving unit are connected to each other by connecting the scan electrodes to the inside of the connection line made of the same material. Since the resistance value of each scanning electrode lead-out line formed with a scanning electrode auxiliary line made of a material much smaller than the specific resistance of the connection line is very small, there is a difference in each wiring length (variation).
Even if there is, the difference (variation) in each resistance value is eliminated. The same applies to the signal electrode lead wire. Therefore,
Compared with the conventional method, the variation in voltage drop is reduced, and it is possible to prevent the difference (variation) in applied voltage between each electrode. As a result, there is no unevenness in the contrast in the vertical and horizontal directions of the screen, and the display quality is improved. Can be improved. In this case, the scanning electrode lead line and the signal electrode lead line are
Indium oxide is used as the connecting line, aluminum is used as the scan electrode auxiliary line and the signal electrode auxiliary line, and the resistance values of the scan electrode lead line and the signal electrode lead line are as follows. Adjustment is performed by changing the wiring width, wiring length, and film thickness of the wires and the auxiliary lines for signal electrodes.
The variation in resistance value can be reduced to about 4% as compared with the previous one.

[Brief description of drawings]

FIG. 1 is a plan view showing a liquid crystal display device according to the present invention.

FIG. 2 is a cross-sectional view of the liquid crystal display device according to the embodiment of the present invention, as seen from section plane lines X3-X3 and X4-X4 in FIG.

FIG. 3 is a cross-sectional view of the portion of the scanning electrode lead wire 13 of FIG. 2A and the portion of the signal electrode lead wire 10 of FIG. 2B as seen from cutting plane lines X6-X6 and X5-X5, respectively. Is.

FIG. 4 is a diagram showing a resistance value of each scan electrode lead line 13 and a resistance value of each scan electrode auxiliary line 14;

FIG. 5 is a diagram for explaining the wiring resistance of various scanning electrode lead wires 13.

FIG. 6 is a portion of the scanning electrode lead wire 13 of FIG.
It is sectional drawing which looked at the modification of the lead wire 10 for signal electrodes of FIG.2 (b) from cutting plane line X6-X6, X5-X5, respectively.

FIG. 7 is a plan view showing a conventional liquid crystal display device.

8 is a sectional view taken along the sectional lines X1-X1 and X2-X2 in FIG. 7.

FIG. 9 is a diagram for explaining the wiring lengths of the lead lines 13 for scanning electrodes and the lead lines 10 for signal electrodes.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Liquid crystal panel 4 ... Scan electrode 5 ... Signal electrode 10 ... Signal electrode lead-out line 11 ... Signal electrode auxiliary line 12 ... Signal electrode voltage driver 13 ... Scan electrode lead-out line 14 ... Scan electrode auxiliary line

Claims (3)

[Claims] 1. A liquid crystal panel having a plurality of scan electrodes, a plurality of signal electrodes, a scan electrode voltage driver for applying a drive voltage to the plurality of scan electrodes, and a drive voltage for the signal electrodes to the plurality of signal electrodes. In a liquid crystal display device having a voltage driving unit, each of the plurality of scanning electrodes and each electrode of the voltage driving unit for scanning electrodes is connected to the inside of a connecting line made of the same material as the scanning electrode. The same as the signal electrode by connecting each of the plurality of signal electrodes and each electrode of the signal electrode voltage driving unit with each of the plurality of signal electrodes and each of the plurality of signal electrodes, which is formed of an auxiliary line for a scanning electrode, which is made of a material extremely smaller than a specific resistance. A liquid crystal display device, comprising: a connecting wire made of a material, and a lead wire for a signal electrode in which an auxiliary wire for a signal electrode made of a material having a material resistance much smaller than that of the connecting wire is formed. 2. The scanning electrode lead-out line and the signal electrode leading-out line use indium oxide as their connecting line, and aluminum as the scanning electrode auxiliary line and the signal electrode auxiliary line. And claim 1
The liquid crystal display device according to item 1. 3. The resistance values of the scanning electrode lead lines and the signal electrode lead lines are adjusted by changing the wiring widths, wiring lengths, and film thicknesses of the scanning electrode auxiliary lines and the signal electrode auxiliary lines. The liquid crystal display device according to claim 1, wherein: