JP4222051B2 - Liquid crystal display - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a reflective liquid crystal display device that performs display by controlling reflection from external light using liquid crystal.
[0002]
[Prior art]
In general, as shown in FIG. 2, for example, the liquid crystal display device is divided into an effective pixel portion 1 that is visible from the outside and a peripheral dummy pixel portion 2 that is shielded from the outside. This is because potential fluctuations occur in the signal line due to charging / discharging of the thin film transistor. By driving the dummy pixel portion 2 around the effective pixel portion 1, the potential fluctuation is made uniform. This is for improving the display image quality. Further, the dummy pixel unit 2 is provided around the effective pixel unit 1 so that the dummy pixel unit 2 absorbs external electrostatic stress and the like so that a defective pixel is not formed in the effective pixel unit 1. (For example, refer to Patent Document 1).
[0003]
Therefore, in the conventional reflective liquid crystal display device, the effective pixel portion 1 and the dummy pixel portion 2 have a difference in the panel structure as shown in FIG. That is, as shown in FIG. 3A, the panel structure in the effective pixel portion 1 includes a driving substrate 11, a counter substrate 12, and a liquid crystal layer 13 held therebetween. On the counter substrate 12 side of the liquid crystal layer 13, the counter electrode 14 made of an ITO (Indium Tin Oxide) film or the like, and each color of R (red), G (green), and B (blue) are provided. A corresponding color filter film 15 is arranged. Further, on the driving substrate 11 side of the liquid crystal layer 13, in addition to the reflective electrode 16 made of an Ag (silver) film or the like, an Al (aluminum) film 17a constituting a gate line, a signal line or the like, PS (polystyrene resin) A film 17b and a Mo (molybdenum) film 17c are stacked. On the other hand, since the panel structure in the dummy pixel portion 2 needs to be shielded, as shown in FIG. 3B, in addition to the panel structure in the effective pixel portion 1, the counter substrate 12 and the color filter A black mask film 18 is disposed between the film 15.
[0004]
[Patent Document 1]
JP-A-7-333654
[Problems to be solved by the invention]
By the way, in the conventional liquid crystal display device, as described above, the difference between the effective pixel portion 1 and the dummy pixel portion 2 is only the presence or absence of the black mask film 18, and the other portions have substantially the same panel structure. . However, the total thickness of the effective pixel portion 1 and the dummy pixel portion 2, that is, the distance between the driving substrate 11 and the counter substrate 12 is the same. Accordingly, in the dummy pixel portion 2, it is necessary to reduce the thickness of the liquid crystal layer 13 by the amount of the black mask film 18.
[0006]
However, when the liquid crystal layer 13 is thinned, the gap between the counter electrode 14 and the reflective electrode 16 is naturally narrowed. Therefore, for example, when the peeling of the reflective electrode 16 occurs, the reflective electrode 16 is easily short-circuited with the counter electrode 14. Such a short-circuit between the electrodes causes a decrease in yield at the manufacturing stage of the liquid crystal display device, and also causes a decrease in reliability after manufacturing. Therefore, the occurrence should be avoided as much as possible. However, in recent years, where the thinning of the liquid crystal display device is strongly demanded, the thickness of the reflective electrode 16 itself tends to be thin. However, the thinning of the reflective electrode 16 itself is easy to peel off the reflective electrode 16. (Easiness of turning) can be induced, and if the panel structure is not distinguished between the effective pixel portion 1 and the dummy pixel portion 2, it is weak against electrode peeling, and it cannot be said that the occurrence of a short circuit between the electrodes can be effectively avoided. .
[0007]
Accordingly, the present invention optimizes the panel structure in each of the effective pixel portion and the dummy pixel portion, thereby preventing electrode breakage in the dummy pixel portion of the liquid crystal display device and preventing the occurrence of a short circuit between the electrodes. Accordingly, it is an object to provide a liquid crystal display device that is expected to improve reliability and quality.
[0008]
[Means for Solving the Problems]
The present invention is a liquid crystal display device devised to achieve the above object. That is, a liquid crystal display device having a panel structure including a driving substrate, a counter substrate, and a liquid crystal layer held between them, and a reflective electrode disposed on the driving substrate side of the liquid crystal layer. An effective pixel portion visible from the outside, and a dummy pixel portion shielded from the outside around the effective pixel portion, and the reflective electrode in the effective pixel portion is formed of a metal film, The reflective electrode is formed of a transparent conductive film instead of the metal film .
[0009]
Since the dummy pixel portion is for equalizing potential fluctuations and absorbing external static stress, the display of the panel structure need not be considered. Therefore, there is no problem even if the reflective electrode in the effective pixel portion needs to be formed of a metal film such as an Ag film, or the reflective electrode in the dummy pixel portion is formed of a transparent conductive film. This transparent conductive film is typified by, for example, an ITO film, but is less susceptible to peeling compared to a gold continuous film such as an Ag film. Therefore, if the reflective electrode in the dummy pixel portion is formed of a transparent conductive film instead of a metal film, it is possible to effectively prevent occurrence of a short circuit between the electrodes due to electrode peeling.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a liquid crystal display device according to the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing an example of a main configuration of a liquid crystal display device according to the present invention. Here, only differences from the conventional liquid crystal display device (see FIGS. 2 and 3) will be described, and the same reference numerals are given to the same components as those of the conventional device, and the description thereof is omitted.
[0011]
The liquid crystal display device described in this embodiment is different from the conventional liquid crystal display device in the panel structure of the dummy pixel portion 2. That is, as shown in FIG. 1, the panel structure of the dummy pixel unit 2 includes a driving substrate 11, a counter substrate 12, and a liquid crystal layer 13 held therebetween, and the liquid crystal layer 13 is disposed on the counter substrate 12 side. A counter electrode 14 made of an ITO film, a color filter film 15 corresponding to each color of R, G, and B, and a black mask film 18 that shields light are arranged, and reflected to the driving substrate 11 side of the liquid crystal layer 13. The electrode 19 and the Al film 17a, the PS film 17b, and the Mo film 17c constituting the gate line, the signal line, and the like are arranged, but the reflective electrode 19 is formed of a transparent conductive film instead of an Ag film. It is different from the conventional one.
[0012]
A typical example of the transparent conductive film for forming the reflective electrode 19 is an ITO film. However, SnO ₂ (tin oxide) may be used in addition to ITO as long as it is a transparent conductive metal oxide film.
[0013]
As described above, in the liquid crystal display device described in the present embodiment, the effective pixel portion 1 that is visible from the outside in plan view and the peripheral dummy pixel portion 2 that is blocked by the black mask film 18 from the outside are provided. Although it has, the panel structure between these differs from each other. This is because the dummy pixel portion 2 is used for uniform potential fluctuation and absorption of external electrostatic stress, and therefore, it is not necessary to consider display for the panel structure. . That is, even if the reflective electrode 16 in the effective pixel portion 1 needs to be formed of, for example, an Ag film, the reflective electrode 19 in the dummy pixel portion 2 can be formed of a transparent conductive film without any problem. From this, the reflective electrode 19 in the dummy pixel portion 2 is formed not by the Ag film but by the transparent conductive film.
[0014]
It has been empirically found that the transparent conductive film forming the reflective electrode 19, that is, a metal oxide film such as ITO, is less prone to peeling than a metal film such as Ag. Therefore, if the reflective electrode 19 is formed of a transparent conductive film, the gap between the electrodes in the dummy pixel portion 2 is narrower than that of the effective pixel portion 1 by the amount of the black mask film 18, so Even if it is easy to short-circuit with the electrode 14, it is possible to prevent occurrence of a short-circuit between the electrodes due to the electrode peeling.
[0015]
This is particularly effective when dealing with thinning of the liquid crystal display device. That is, even if it is necessary to reduce the thickness of the reflective electrode 19 itself, the effective pixel portion 1 and the dummy pixel portion 2 have different panel structures, so that the reflective electrode 19 in the dummy pixel portion 2 is turned off. Therefore, the occurrence of a short circuit between electrodes due to electrode peeling can be effectively avoided.
[0016]
As described above, in the liquid crystal display device according to the present embodiment, it is possible to effectively prevent the occurrence of a short circuit between the electrodes. Therefore, the occurrence of a short circuit in the manufacturing stage is suppressed as much as possible. As a result, the yield can be improved as compared with the prior art. Further, even after manufacturing, it is possible to eliminate as much as possible the possibility of occurrence of a short circuit between electrodes over time, thereby improving the reliability of the liquid crystal display device. In addition, since the function as the dummy pixel portion 2 is sufficiently secured, it is possible to achieve uniform display of potential fluctuation, absorption of electrostatic stress from the outside, and the like, thereby realizing a good display image quality.
[0017]
Furthermore, since it is only necessary to form the reflective electrode 19 in the dummy pixel portion 2 with a transparent conductive film, a process merit is obtained in that changes in the manufacturing stage can be minimized as compared with the conventional case.
[0018]
Although the present embodiment has been described with reference to a suitable specific example for carrying out the present invention, the present invention is not limited to this and can be variously modified. That is, the materials, shapes, and the like of the series of constituent elements that constitute the liquid crystal display device described in the present embodiment are not necessarily limited to those described in the present embodiment, and the functions of the respective constituent elements are similarly ensured. You can change it as much as possible.
[0019]
【The invention's effect】
As described above, the liquid crystal display device according to the present invention is a reflection type liquid crystal display device that performs display by controlling reflection from external light using liquid crystal, and each has an effective pixel portion and a dummy pixel portion with a panel structure. Therefore, it is possible to effectively prevent the occurrence of a short circuit between the electrodes due to the electrode peeling in the dummy pixel portion. Therefore, according to the liquid crystal display device according to the present invention, it is possible to effectively prevent the occurrence of a short circuit between the electrodes.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating an example of a main configuration of a liquid crystal display device according to the present invention.
FIG. 2 is a schematic diagram showing an example of a planar structure in a conventional liquid crystal display device.
3A and 3B are cross-sectional views illustrating an example of a configuration of a main part of a conventional liquid crystal display device. FIG. 3A is a diagram illustrating a panel structure in an effective pixel portion, and FIG. 3B is a diagram illustrating a panel structure in a dummy pixel portion. is there.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Effective pixel part, 2 ... Dummy pixel part, 11 ... Substrate for drive, 12 ... Counter substrate, 13 ... Liquid crystal layer, 14 ... Counter electrode, 15 ... Color filter film, 17a ... Al film, 17b ... PS film, 17c ... Mo film, 18 ... Black mask film, 19 ... Reflective electrode

Claims (2)

A reflective liquid crystal display device having a panel structure comprising a drive substrate, a counter substrate, and a liquid crystal layer held between them, and a reflective electrode disposed on the drive substrate side of the liquid crystal layer. There,
It has an effective pixel portion that can be visually recognized from the outside, and a dummy pixel portion that is shielded from the outside around it,
The reflective electrode in the effective pixel portion is formed of a metal film,
The liquid crystal display device, wherein the reflective electrode in the dummy pixel portion is formed of a transparent conductive film instead of the metal film . The liquid crystal display device according to claim 1, wherein the metal film is an Ag film.

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