JP2545175Y2 - Liquid crystal display - Google Patents

Description

The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device, in which a plurality of display pixels are formed of individual pixel electrodes, and the pixel electrodes are commonly connected in one direction at each edge. The present invention relates to a matrix type liquid crystal display device having a signal line.

Prior Art A typical prior art is shown in FIG. The liquid crystal display device 1 is a matrix type liquid crystal display device. A plurality of pixel electrodes 3 are formed in a matrix pattern on a transparent substrate 2 made of a material such as glass. A plurality of signal lines 4 are formed along one arrangement direction of the pixel electrodes 3. The plurality of pixel electrodes 3 arranged along the one arrangement direction are connected in parallel to the same signal line 4, and a signal voltage is supplied from the signal line 4.

A transparent electrode 6 extending in parallel with a direction intersecting with the signal line 4 is formed in a pattern on a surface of the transparent substrate 5 facing the transparent substrate 2 and facing the transparent substrate 2.

The space between the transparent substrates 2 and 5 is filled with, for example, a twisted nematic (hereinafter referred to as “TN”) type liquid crystal.
In such a case, polarizing plates 7 and 8 are disposed on the surface of the transparent substrate 2 on the side opposite to the transparent substrate 5 and on the surface of the transparent substrate 5 on the side opposite to the side on which the transparent electrode 6 is formed. Is established.

A scanning pulse is sequentially and cyclically applied to the plurality of transparent electrodes 6. A signal voltage corresponding to a video signal to be displayed is applied to the plurality of signal lines 4 in parallel. As a result, each display pixel becomes translucent or light-blocking, and an image is displayed.

As a material of the signal line 4, tantalum, titanium, Alternatively, chrome or the like is used.

However, these materials have relatively high specific resistance,
Good display characteristics cannot be obtained in the liquid crystal display device 1. From the end 4 a of each signal line 4, the capacitance of the pixel electrode 3, the capacitance of the signal line 4, or when an active element is provided in connection with each pixel electrode 3, the capacitance of the active element can be charged. The charge time constant depends on the electric resistance of the signal line 4. Therefore, when the signal line 4 is formed using a material having a relatively high specific resistance as described above, good display quality cannot be obtained, for example, when driving a large matrix liquid crystal display device. . That is,
As the size of the liquid crystal display device increases, for example, the width and pitch of the signal lines 4 are kept unchanged, and the length of the signal lines 4 and the number of pixel electrodes 3 borne by each signal line 4 increase. Width, length of signal line 4, length and width of pixel electrode 3,
In any case where the length and width of the active element are all large, the charging time constant for each capacitance component increases. Since the charging time constant increases with the resistance component of the signal line 4, in the multiplex driving as described above, the display pixels near and far from the end 4a to which the signal voltage of the signal line 4 is supplied are connected. Between the display characteristics.

In order to solve such a problem, in another prior art, as shown in FIG. 5, a signal line 4 is formed of a lower signal line 41 made of a metal material having a low electric resistance and a metal line having a high corrosion resistance and weather resistance. And an upper signal line 42 made of a material.

Problems to be Solved by the Invention In forming such a pattern of the signal line 4, a metal thin film made of the material of the lower signal line 41 is formed over the entire surface of the transparent substrate 2 facing the liquid crystal layer. A metal thin film made of the material of the upper signal line 42 is formed continuously on the thin film, and thereafter, patterning is performed by, for example, etching. As a result, the lower signal line 41 has an exposed portion, which is insufficient in corrosion resistance and weather resistance.

An object of the present invention is to form a signal line having a low electric resistance on a substrate without impairing the corrosion resistance and weather resistance of the signal line, thereby obtaining good display characteristics, and its large size. An object of the present invention is to provide a liquid crystal display device that is particularly advantageous for shaping.

Means for Solving the Problems In the present invention, a liquid crystal is filled between two opposing substrates,
On the inner surface of one of the substrates, a plurality of pixel electrodes arranged in a matrix and a plurality of signal lines arranged in the arrangement gap of the pixel electrodes and commonly connecting the pixel electrodes along the row direction are provided. On the inner surface of the other substrate, a plurality of electrodes facing the pixel electrodes and arranged in parallel along the column direction are patterned, and a drive is selectively supplied to the electrodes and the pixel electrodes. In a liquid crystal display device in which the liquid crystal is displayed and driven in pixel units by a voltage, a drive voltage supplied from the periphery of the one substrate to an end of the signal line is transmitted to the pixel electrode via the signal line. The signal line is composed of a coating layer made of a metal material having high corrosion resistance and weather resistance and a core wire made of a metal material having a lower electric resistance than the coating layer, and the coating layer is formed along the surface of the core wire. Core wire surface The covering layer and the cross section of the core wire are both formed into a square shape, and the thickness of the coating layer located on both sides of the core wire is caused by exposure and development of a photoresist deposited after the formation of the core wire. It is characterized in that the gap substantially corresponds to a gap generated between the photoresist and the core wire due to overdeveloping.

In the present invention, a signal line for supplying a signal to a pixel electrode for driving a liquid crystal display device is provided with a film thickness adjusted by utilizing over-development caused by exposure and development of a photoresist. It comprises a coating layer made of a relatively high metal material and a core wire made of a metal material having lower electric resistance than the coating layer, and the exposed portion is entirely covered by the coating layer. As a result, the signal line with low electrical resistance
It is formed on at least one substrate of the liquid crystal display device without deteriorating the corrosion resistance and weather resistance and without lowering the aperture ratio of the pixel region. As a result, good display characteristics can be realized in the liquid crystal display device, and even when the size of the liquid crystal display device is increased, uniform display characteristics can be obtained over the entire display area.

Embodiment FIG. 1 is a perspective view showing a basic configuration of a liquid crystal display device 11 according to an embodiment of the present invention. For example, a plurality of pixel electrodes 13 are formed in a matrix on one surface of a transparent substrate 12 made of a material such as glass. A plurality of signal lines 14 for supplying a signal voltage corresponding to a video signal to each pixel electrode 13 are formed in a pattern along one arrangement direction of the plurality of pixel electrodes 13.

The transparent substrate 15 is disposed so as to face the surface of the transparent substrate 12 on which the pixel electrodes 13 and the like are formed. On a surface of the transparent substrate 15 facing the transparent substrate 12, a plurality of transparent electrodes 16 extending in a direction intersecting the plurality of signal lines 14 are formed in a pattern. The space between the transparent substrates 12 and 15 is filled with, for example, a twisted nematic (hereinafter, referred to as “TN”) type liquid crystal (not shown). In this case, polarizing plates 17 and 18 are provided on the surfaces of the transparent substrates 12 and 15 opposite to the liquid crystal layer.

An alignment film (not shown) is formed on the transparent substrates 12 and 15 so as to cover the surfaces facing the respective liquid crystal layers, and alignment processing is performed, for example, at an angle of 90 degrees with each other. Thereby, the liquid crystal molecules constituting the liquid crystal layer are:
A 90-degree twist alignment is formed between the alignment films. In such a case, for example, the polarizing plates 17 and 18 are arranged such that the directions of the respective polarization axes are parallel or perpendicular to each other.

A scanning pulse is sequentially and cyclically applied to the plurality of transparent electrodes 16. From one end 14a of each of the plurality of signal lines 14, a signal voltage based on a video signal corresponding to the transparent electrode 16 to which the scanning pulse is applied is applied in parallel. Thus, in the liquid crystal display device 11, each transparent electrode 16
Are time-divisionally driven for each of the plurality of pixel electrodes 13 corresponding to. Display driving is performed by a so-called multiplex method to display an image.

As will be described in detail later in the manufacturing process of FIG. 2, the signal line 14 includes a core wire 141 made of, for example, aluminum, gold, silver, or an alloy containing these, and
And a coating layer 142 made of titanium, tantalum, chromium, or an alloy containing them. Aluminum, gold, silver or alloys containing them have sufficiently low electric resistance, and titanium, tantalum, chromium or alloys containing these have good resistance to etching solutions such as acids and alkalis. In addition, resistance to changes in temperature and humidity and aging, that is, weather resistance is good. Therefore, the signal line 14 configured as described above is formed with a relatively low electric resistance, and is not eroded or changed in properties during the manufacturing process of the liquid crystal display device.

FIG. 2 is a sectional view showing a step of patterning the signal line 14. A core wire 141 made of, for example, aluminum is pattern-formed on one surface of the transparent substrate 12. In such a state, the negative photoresist 20 is applied to the entire surface of the transparent substrate 12 on the side where the core wire 141 is patterned. Such a state is shown in FIG. 2 (1). From this state, the back side of the transparent substrate 12, that is, the core wire
Light is irradiated in the direction of arrow 21 shown in FIG. 2A from the side opposite to the side on which the pattern 141 is formed.

Next, the exposed negative photoresist 20 is developed. At this time, the developing time or the developer concentration is increased more than usual. Is adjusted so that the resist removal width 22 (see FIG. 2 (2)) is larger than the width 23 of the core wire 141. The state after the development is shown in FIG.

From such a state, the metal material film 24 made of the material of the coating layer 142 is applied to cover the entire exposed surface on the side where the core wire 141 and the negative photoresist 20 of the transparent substrate 12 are formed. Such a state is shown in FIG. 2 (3).

The cover layer 142 is patterned by a so-called lift-off method of peeling the negative photoresist 20 from this state. Such a state is shown in FIG. 2 (4).

FIG. 3 shows another method for patterning the signal line 14 on the transparent substrate 12. That is, in a state where the core wire 141 is patterned on the transparent substrate 12, covering the surface of the transparent substrate 12 on the side where the core wire 141 is formed,
A negative photoresist 20 is applied, and in such a state, light is irradiated in the direction of arrow 25 from the back side of the transparent substrate 12, that is, the side opposite to the side on which the core wire 141 is patterned. At this time, the light scattering plate 26 is arranged on the side of the transparent substrate 12 opposite to the core wire 141. As a result, the exposure amount in the vicinity of the core wire 141 can be relatively reduced, so that it is not necessary to perform the above-described overdevelopment in the subsequent development process.

As described above, in the present embodiment, the signal line 14 includes the core 141 made of a metal material having a relatively low electrical resistance, and the core 141
And a coating layer 142 made of a metal material having high corrosion resistance and high weather resistance. As a result, the signal line 14 having a low electric resistance can be configured without impairing the corrosion resistance and the weather resistance,
Therefore, the charging time constant of the capacitance related to the signal line 14 can be reduced.

Thus, the display characteristics of the liquid crystal display device 11 are significantly improved. Further, since the signal line 14 has a low electric resistance, good display characteristics can be obtained even when the liquid crystal display device 11 is relatively large.

Effect of the Invention As described above, according to the present invention, the signal line is configured to have a low electric resistance without deteriorating the corrosion resistance and the weather resistance, and therefore, the display characteristics of the liquid crystal display device are significantly improved. can do. Further, since the signal lines are configured to have a low electric resistance, the display characteristics do not deteriorate without the disadvantage that the signal lines lower the aperture ratio of the display screen as the size of the liquid crystal display device increases. .

That is, the present invention is characterized in that the core wire, which is a low-resistance metal material, is entirely coated with a coating layer having excellent corrosion resistance and weather resistance. Therefore, since the entire surface of the core wire portion can be protected, remarkable corrosion resistance and weather resistance can be obtained in the step after the formation of the metal wiring in the production of the liquid crystal display device.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a basic structure of a liquid crystal display device 11 according to an embodiment of the present invention, and FIG.
FIG. 3 is a cross-sectional view showing a process for forming the signal line 14, FIG. 3 is a cross-sectional view showing another process for forming the signal line 14, and FIG. 4 is a perspective view showing a basic configuration of a typical prior art liquid crystal display device 1. Figure, fifth
The figure is an enlarged perspective view showing a configuration of a signal line 4 used in another prior art. 11: liquid crystal display device, 12, 15, transparent substrate, 13: pixel electrode, 1
4 ... Signal line, 16 ... Transparent electrode, 20 ... Negative photoresist, 141 ... Core wire, 142 ... Coating layer

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-55-138259 (JP, A) JP-A-60-9167 (JP, A) JP-B-51-3194 (JP, B1)

Claims (1)

(57) [Scope of request for utility model registration] A liquid crystal is filled between two opposing substrates,
On the inner surface of one of the substrates, a plurality of pixel electrodes arranged in a matrix and a plurality of signal lines arranged in the arrangement gap of the pixel electrodes and commonly connecting the pixel electrodes along the row direction are provided. On the inner surface of the other substrate, a plurality of electrodes facing the pixel electrodes and arranged in parallel along the column direction are patterned, and a drive is selectively supplied to the electrodes and the pixel electrodes. In a liquid crystal display device in which the liquid crystal is displayed and driven in a pixel unit by a voltage, a driving voltage supplied from the periphery of the one substrate to an end of the signal line is transmitted to the pixel electrode via the signal line. The signal line is composed of a coating layer made of a metal material having high corrosion resistance and weather resistance, and a core wire made of a metal material having a lower electric resistance than the coating layer, and the coating layer is formed along the surface of the core wire. Core table The coating layer and the cross section of the core wire are both formed into a square shape, and the thickness of the coating layer located on both sides of the core wire is determined by exposure and development of a photoresist deposited after the formation of the core wire. A liquid crystal display device substantially corresponding to a generated gap between the photoresist and the core wire caused by overdeveloping.