JP2000275658A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display device, capable of reducing power variation in the internal power wiring of video signal line drive circuit and scanning line drive circuits by covering the resistor value reducing technology. SOLUTION: This liquid crystal display device has a liquid crystal display device, in which switching elements are connected to plural scanning lines formed on a substrate and plural video signal line orthogonal to the scanning lines, and is provided with drive circuit which applies a scanning pulse to the switching elements via the scanning lines and applies video signals to the video signal lines on the peripheral end part of the substrate. In this case, among the multiple power lines 22 for supplying operating power to the drive circuits, plural power lines are provided side by side on the substrate, and also a conductive layer straddling over the plural power lines is laminated via a dielectric layer 24.

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 in which switching elements are formed on a plurality of scanning lines and a plurality of video signal lines orthogonal to the scanning lines, and a switching element via the scanning lines. The present invention relates to a liquid crystal display device in which a scanning line driving circuit for applying a scanning pulse and a video signal driving circuit for applying a video signal to a video signal line are formed integrally on a substrate.

[0002]

2. Description of the Related Art An active matrix type liquid crystal display device in which a switching element as an active element is arranged for each liquid crystal display element has been widely used as a graphic display for information equipment terminals and thin televisions. In particular, in recent years, in order to increase the effective screen area on a transparent thin film substrate having the same area and reduce the manufacturing cost, the scanning line driving circuit and the video signal line driving circuit are mounted on the transparent insulating substrate in the same manner as the switching elements. The development of an active matrix type liquid crystal display device with a built-in drive circuit integrally formed with a liquid crystal display device is progressing.

FIG. 4 is a plan view showing a schematic structure of this type of liquid crystal display device. In FIG. 1, a large number of display pixel electrodes 11 are arranged in a matrix in a display area of a glass substrate 1, and a pixel capacitance is formed by a liquid crystal layer 12 and a counter electrode 13 formed on an inner surface of a counter substrate (not shown). are doing. Among them, each of the display pixel electrodes 11 is connected to the video signal lines X1, X2,.
.., Xn. The gates of the thin film transistors 10 are commonly connected to scanning lines Y1, Y2,..., Yn for each row. A selection pulse is applied to the scanning lines Y1, Y2,..., Yn in the order in which the lines are arranged by the scanning line driving circuit 3, and the thin film transistor 10 conducts in synchronization with the application timing of the selection pulse, and the video signal lines X1, X2,. …, X
The display signal on n is applied to the display pixel electrode 11. On the other hand, the display signals output from the video signal line driving circuit 2 are sequentially applied to the video signal lines X1, X2,.

The video signal line driving circuit 2 has an internal power supply line 4 for supplying driving power thereto, and the scanning line driving circuit 3 similarly has an internal power supply line 5 for supplying driving power thereto. ing. A signal wiring 6 for supplying a video signal to the video signal line driving circuit 2 and a power supply wiring 7 for supplying power to the internal power supply wiring 4 are provided at a lower right end portion of the substrate 1 as shown in FIG. Input portions of a signal wiring 8 for supplying a scanning line driving signal and a power supply wiring 9 for supplying power to the internal power supply wiring 5 are provided at a lower right end of the substrate 1 as shown in the drawing.

[0005]

The active matrix type liquid crystal display device with a built-in driving circuit described above has a configuration in which a circuit is provided on substantially the entire surface of a display screen and operating power is supplied from the outside. In some cases, the length of the power supply line is increased, and the voltage of the power supply line fluctuates depending on the power consumption state in the circuit.

As a conventional method of suppressing the voltage fluctuation, there is a method of reducing the resistance value of the internal power supply wires 4 and 5. Specific methods include the following methods a, b, and c. a. A material having a small specific resistance is used as a wiring material. b. Increase the thickness of the wiring. c. Increase the width of the wiring.

[0007] Of the above three methods, the methods a and b have technical limitations, and the method c is difficult to adopt to narrow the effective screen area.

The present invention has been made in view of the above circumstances, and its object is to supplement conventional resistance reduction techniques.
It is an object of the present invention to provide a liquid crystal display device capable of suppressing a power supply fluctuation of an internal power supply wiring of a video signal line driving circuit or a scanning line driving circuit.

[0009]

In many cases, elements constituting a display screen of a liquid crystal display device with a built-in driving circuit do not operate simultaneously but sequentially operate at staggered times. Therefore, by capacitively coupling a plurality of internal power supply lines, fluctuations in the power supply voltage can be suppressed low.

Therefore, the present invention has a liquid crystal display device in which switching elements are connected to a plurality of scanning lines formed on a substrate and a plurality of video signal lines orthogonal to the scanning lines. In a liquid crystal display device in which each driving circuit that applies a scanning pulse to a switching element via a switching element and applies a video signal to a video signal line is provided at an edge of a substrate, a multi-system that supplies operating power to the driving circuit is provided. Among the power supply lines, a plurality of power supply lines are arranged in parallel on a substrate, and a conductor layer extending over the plurality of power supply lines is laminated via a dielectric layer. In this case, it is preferable to form the conductor layer by dividing it in the longitudinal direction of the power supply line.

Another aspect of the invention is a liquid crystal display device having a switching element connected to a plurality of scanning lines formed on a substrate and a plurality of video signal lines orthogonal to the scanning lines. In a liquid crystal display device in which each driving circuit that applies a scanning pulse to a switching element via a switching element and applies a video signal to a video signal line is provided at an edge of a substrate, a multi-system that supplies operating power to the driving circuit is provided. A plurality of power supply lines among the power supply lines are stacked on a substrate with a dielectric layer interposed therebetween.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on preferred embodiments shown in the drawings. FIG. 1 is a perspective view partially showing a detailed structure of an internal power supply wiring in a cross section as a first embodiment of a liquid crystal display device according to the present invention. As described above, the internal power supply line 4 that supplies drive power to the video signal line drive circuit 2 has multiple power supply lines connected to the power supply line 7, and similarly supplies drive power to the internal power supply line 5. The internal power supply wiring 5 has multiple power supply lines connected to the power supply wiring 9.

This embodiment employs silicon oxide (eg, _Si
A power supply line 22 and a power supply line 23 made of aluminum (Al) are formed substantially in parallel on an insulator layer 21 made of O ₂ ). A dielectric layer 24 made of silicon oxide or the like is formed on the surface of the insulator layer 21 including these power supply lines. Then, a conductor layer 25 made of, for example, aluminum having a planar shape over both the power supply line 22 and the power supply line 23 is formed on the surface of the dielectric layer 24.
Are formed. An insulator layer (not shown) is laminated on the surface of the conductor layer 25.

Incidentally, the width W of the power supply lines 22 and 23 is formed to be 50 to 100 μm, the thickness t ₁ is formed to be about 400 nm, and the mutual interval D is formed to be about 100 μm. The thickness T of the dielectric layer 24 laminated on the power supply lines 22 and 23
Is about 500 nm, and the thickness t ₂ of the conductor layer 25 is 400 to 5
It is laminated to a thickness of about 00 nm.

Here, the power supply line 22 and the conductor layer 25 are capacitively coupled, and the conductor layer 25 and the power supply line 23 are capacitively coupled. If the voltage polarity of the power supply line 22 is positive and the voltage polarity of the power supply line 23 is negative, the portion of the conductor layer 25 facing the power supply line 22 is negatively charged, and Is positively charged. Therefore, even if the voltage of the power supply line 22 is to change, if the voltage of the power supply line 23 is constant, the charged state of the conductor layer 25 is hard to change.
The voltage change of the power supply line 22 capacitively coupled to the power supply line 5 is suppressed.

The suppression of the voltage change is not limited to the case where the power supply line 22 and the power supply line 23 have a potential difference. Even if the potentials are the same, a similar result can be obtained because signals are applied with a time shift. . Further, even if the conductor layer 25 is formed so as to straddle two or more power supply lines, the voltage change can be similarly suppressed.

Thus, according to the first embodiment shown in FIG. 1, it is possible to suppress the fluctuation of the power supply of the internal power supply wiring of the video signal line driving circuit and the scanning line driving circuit by supplementing the resistance reduction technique. it can.

FIG. 2 is a perspective view, partially in section, showing a detailed configuration of internal power supply wiring as a second embodiment of the liquid crystal display device according to the present invention. In the figure, the same elements as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted. In this embodiment, the conductor layer 25 shown in FIG. 1 is divided into a state in which it is electrically insulated in the longitudinal direction of the power supply line 22 and the power supply line 23. Are divided into several mm and the interval S is divided into 0.2 to 0.3 mm to form conductor layers 26, 27, 28,.

In this embodiment, in addition to suppressing the fluctuation of the power supply, a power supply short circuit between the power supply lines 22 and 23 is prevented. That is, since the facing length between the power supply lines 22 and 23 and the conductor layer 25 in FIG. 1 is long, the power supply line 22 and the conductor layer 25 are short-circuited or the power supply line 23 and the conductor layer 25 are short-circuited. Power supply increases, and a power supply short-circuit easily occurs. On the other hand, as shown in FIG. 2, when the power supply lines 22 and 23 are divided in the longitudinal direction as conductor layers 26, 27, 28,. Layer 2
Even if 7 short-circuits to the power supply line 23, no power supply short-circuit occurs. If the conductor layer 26 is short-circuited to the power supply line 22 and also to the power supply line 23, the power supply is short-circuited.
The probability that a situation in which the conductor layer 26 is short-circuited to both the power supply lines 22 and 23 occurs stochastically is extremely low.
Power supply short circuit can be prevented beforehand.

FIG. 3 is a perspective view partially showing a detailed configuration of an internal power supply wiring in a cross section as a third embodiment of the liquid crystal display device according to the present invention.

In this embodiment, a power supply line 32 made of aluminum is formed on an insulator layer 31 made of silicon oxide,
A dielectric layer 34 made of silicon oxide or the like is formed on the surface of the insulator layer 31 including the power supply line 32. Further, on the surface of the dielectric layer 34, a power supply line 33 of the same material and the same dimensions as the power supply line 32 is laminated. Note that an insulator layer (not shown) is laminated on the surface of the power supply line 33.

Incidentally, the width W of the power supply lines 32 and 33 is 100 to 200 μm, the thickness t is about 400 nm, and the thickness T of the dielectric layer 34 is about 500 nm.

Here, the power supply lines 32 and 33 are capacitively coupled. Therefore, even if the voltage of one power supply line 32 tries to change, if the voltage of the power supply line 33 is constant, the charged state is hard to change. As a result, the power supply line 32 capacitively coupled to this power supply line 33 Is suppressed.

Thus, according to the third embodiment shown in FIG. 3, it is possible to suppress the fluctuation of the power supply of the internal power supply wiring of the video signal line driving circuit and the scanning line driving circuit by supplementing the resistance reduction technique. .

In the third embodiment shown in FIG. 3, two power supply lines are stacked, but the same effect as described above can be obtained by connecting more power supply lines in multiple layers.

[0026]

As is apparent from the above description, all of the present invention skillfully utilizes the characteristic that the elements constituting the drive circuit operate not sequentially at the same time but sequentially at different times. Therefore, it is possible to provide a liquid crystal display device that can suppress the fluctuation of the power supply of the internal power supply wiring of the video signal line driving circuit and the scanning line driving circuit by supplementing the conventional resistance value reduction technology.

Further, by forming the conductive layer to be capacitively coupled and divided in the longitudinal direction of the power supply line,
There is also obtained an advantage that a power supply short circuit can be prevented beforehand.

[Brief description of the drawings]

FIG. 1 is a perspective view partially showing a detailed configuration of an internal power supply wiring for forming a capacitance between power supply lines as a first embodiment of a liquid crystal display device according to the present invention.

FIG. 2 is a perspective view partially showing a detailed configuration of an internal power supply wiring obtained by dividing a conductor layer forming a capacitor between power supply lines as a second embodiment of the liquid crystal display device according to the present invention.

FIG. 3 is a perspective view partially showing a detailed configuration of an internal power supply wiring in which two power supply lines are stacked, as a third embodiment of the liquid crystal display device according to the present invention.

FIG. 4 is a plan view showing a schematic configuration of an active matrix type liquid crystal display device with a built-in drive circuit to which the present invention is applied;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Glass substrate 1 2 Video signal line drive circuit 3 Scan line drive circuit 4, 5 Internal power supply wiring 6, 8 Signal wiring 7, 9 Power supply wiring 10 Thin film transistor 11 Display pixel electrode 12 Liquid crystal layer 13 Counter electrode 21, 31 Insulator layer 22 , 23,32,33 Power line 24,26,27,28,34 Dielectric layer 25 Conductive layer

Claims (3)

[Claims] 1. A liquid crystal display device having a switching element connected to a plurality of scanning lines formed on a substrate and a plurality of video signal lines orthogonal to the scanning lines. A driving circuit for applying a scanning pulse to the switching element and applying a video signal to the video signal line provided at an edge of the substrate; A liquid crystal display, comprising a plurality of power supply lines of the system power supply lines arranged in parallel on the substrate, and a conductor layer extending over the plurality of power supply lines laminated via a dielectric layer. apparatus. 2. The liquid crystal display device according to claim 1, wherein said conductor layer is formed by being divided in a longitudinal direction of said power supply line. 3. A liquid crystal display device having a switching element connected to a plurality of scanning lines formed on a substrate and a plurality of video signal lines orthogonal to the scanning lines, wherein the liquid crystal display element is connected via the scanning lines. A driving circuit for applying a scanning pulse to the switching element and applying a video signal to the video signal line provided at an edge of the substrate; A liquid crystal display device, wherein a plurality of power supply lines among power supply lines of a system are stacked on the substrate via a dielectric layer.