JP4528531B2 - Liquid crystal display - Google Patents

Description

  The present invention relates to a liquid crystal display device including a plurality of columnar spacers, liquid crystal layers having different thicknesses in one pixel, and a pattern for changing the thickness of the liquid crystal layer formed in a frame portion, and more particularly to an array side substrate. Concerning structure.

  In recent years, as the application of liquid crystal display devices to mobile computers, mobile phones, and the like has further progressed, low power consumption of liquid crystal display devices has become an important requirement for these devices. In order to ensure the visibility of the screen displayed on such a conventional liquid crystal display device, for example, a light source is disposed behind the liquid crystal screen, and light from the light source (backlight) is transmitted through the liquid crystal screen. This ensures good visibility. However, a liquid crystal display device using a backlight is satisfactory in terms of visibility, but on the other hand, it consumes power to turn on the backlight.

  In contrast, the development of reflective liquid crystal display devices that display images by reflecting ambient light incident from outside without using a backlight, and reflective and transmissive liquid crystal display devices that have both transmission and reflection functions have been developed. It is being advanced. In particular, the reflection / transmission type liquid crystal display device has been widely used as a display for a mobile phone because it has good visibility even in a dark place or a bright place.

  In such a reflection-transmission type liquid crystal display device, it is required to obtain optimum optical characteristics both in reflection display and in transmission display. In the reflection-transmission type liquid crystal display device, the length (history) of the path through which light transmitted through the reflection part and the transmission part passes through the liquid crystal layer is different. Length) is different. Therefore, a transflective liquid crystal display device has been developed that has a configuration in which an optimal cell gap is set between the reflective part and the transmissive part by providing a concave pattern in the interlayer insulating film under the transparent electrode to increase the cell gap of the transmissive part. Has been. The transflective liquid crystal display device having such a configuration is called a “multi-gap transflective liquid crystal display device”.

  On the other hand, the liquid crystal display device is provided with various spacers for keeping the thickness of the liquid crystal layer constant. Of these various spacers, the columnar spacers integrally formed on the array substrate by photolithography do not overlap the display area of each pixel for a large number of pixels constituting the display area of the liquid crystal display device. Thus, since it is arranged near the intersection of the scanning line and the signal line, a good display quality can be obtained.

Further, the resin that becomes such a columnar spacer is formed through steps of resin resist coating, exposure, development, and peeling on the transparent insulating film. In this resist coating, the unevenness of the coated surface greatly affects the coating film thickness. In the display area of the above-described multi-gap transflective liquid crystal display device, the level of the resin resist film becomes thinner than the frame portion having a flat coating surface due to the presence of the concave pattern on the coating surface to form a multi-gap. This has caused a cell gap unevenness between the display area and the frame portion. In order to prevent this, a concave pattern is formed also in the frame portion having no pixel electrode, so that the area density of the display area and the frame portion of the liquid crystal display device is configured to be equal. (See Patent Document 1)
JP 2004-20946 A

  However, in the conventional technique, a driving circuit and wiring for supplying a signal to the display area are formed in the frame portion, and the upper portion is covered with a transparent insulating film layer to protect the driving circuit and wiring. The interlayer insulating film has a two-layer structure, and a hole pattern is formed in the upper layer film to form a concave pattern for forming a multi-gap. Conventionally, a concave pattern is also provided on the drive circuit and wiring. For this reason, when there is a minute crack in the lower layer of the insulating film between the layers protecting the drive circuit and the wiring, an etchant (etching solution) enters the crack in the etching process, and the drive circuit and Corresponding to the wiring, corrosion due to a chemical reaction caused by this occurred in the drive circuit and wiring.

  An object of the present invention is to provide a liquid crystal display device in a multi-gap transflective liquid crystal display device, in which the frame portion driving circuit and wiring caused by the concave pattern are not corroded and the manufacturing yield is improved.

  According to the first aspect of the present invention, a plurality of signal lines and a plurality of scanning lines arranged in a matrix, a switching element arranged at each intersection of the signal lines and the scanning lines, the signal lines and the scanning lines And a transparent insulating film layer disposed so as to cover the switching element, and a display region having a plurality of pixel electrodes electrically connected to each of the switching elements through through holes formed in the transparent insulating film layer An array substrate formed around the display region and having a drive circuit for supplying a signal to the display region and a frame portion having wiring; a counter substrate on which a counter electrode facing the pixel electrode is formed; A liquid crystal layer filled between the two substrates, and the pixel electrode includes a reflective pixel electrode that reflects external light and displays an image, and a transmissive pixel electrode that transmits backlight and displays an image. In order to make the thickness of the liquid crystal layer different between the reflective pixel electrode and the transmissive pixel electrode, a concave pattern is formed in the transparent insulating film layer under the transmissive pixel electrode, In the liquid crystal display device in which the concave pattern having the same area density as that of the display area is formed, the concave pattern of the frame portion is arranged avoiding the drive circuit and the wiring.

  In the present invention according to claim 1, the transparent insulating film in which the concave pattern is formed by disposing the concave pattern of the frame portion at a position avoiding the driving circuit and the wiring. Even if a crack occurs, the etching solution is prevented from reaching the drive circuit and wiring.

According to a second aspect of the present invention, in the first aspect of the present invention, the concave pattern of the frame portion is arranged such that the bottom of the concave pattern is located between the wirings in plan view .

The present invention according to claim 2 is characterized in that the concave pattern of the frame portion is arranged such that the bottom of the concave pattern is located between the wirings in a plan view .

According to a third aspect of the present invention, in the first or second aspect, in the concave pattern of the frame portion, the transparent insulating film layer is interposed between the concave pattern and the wiring .

In the present invention according to claim 3, the concave pattern of the frame portion is characterized in that the transparent insulating film layer is interposed between the concave pattern and the wiring .

  According to the present invention, in a multi-gap transflective liquid crystal display device, it is possible to provide a liquid crystal display device in which the manufacturing yield is improved by eliminating the corrosion of the drive circuit and wiring of the frame portion due to the concave pattern.

<First Embodiment>
Embodiments of a liquid crystal display device according to the present invention will be described below with reference to the drawings.

  As shown in the perspective view of FIG. 1, the liquid crystal display device of the present invention includes a liquid crystal display panel 10 and a backlight unit 30. The liquid crystal display panel 10 is disposed between the array substrate 100 as a first substrate, a counter substrate 200 as a second substrate disposed opposite to the array substrate 100, and the array substrate 100 and the counter substrate 200. Liquid crystal composition.

  In such a liquid crystal display panel 10, a display region 102 for displaying an image is formed in a region surrounded by a sealant 106 that bonds the array substrate 100 and the counter substrate 200, and includes a plurality of pixels. A frame portion 104 having various wiring patterns drawn out from the display region 102 is formed on the entire periphery of the edge portion of the display region 102.

  FIG. 2 is a schematic cross-sectional view of a portion indicated by A-A ′ in FIG. 1 for explaining the first embodiment. As shown in FIG. 2, the liquid crystal display panel 10 includes an array substrate 100, a counter substrate 200, and a backlight 30. The array substrate 100 has a transparent insulating substrate 14 such as a glass substrate.

  In the display area 102, a plurality of signal lines 34 and a plurality of scanning lines (not shown) are arranged in a matrix on the transparent insulating substrate 14, and a switching element (not shown) is arranged for each matrix in the matrix. . For example, a thin film transistor (TFT) is used as the switch element.

  Further, a drive circuit and a wiring pattern 32 are arranged in the frame portion 104.

  An upper organic insulating film 16 and a lower interlayer insulating film 33 are formed so as to cover these signal lines 34 and wiring patterns 32. In addition to the multi-gap concave pattern, the organic insulating film 16 is provided with a concave / convex pattern for improving viewing angle characteristics during reflective display.

  Further, the multi-gap hole 19 is opened in the organic insulating film 16 to a depth reaching the lower interlayer insulating film 33 as a concave pattern for making a difference in the thickness of the liquid crystal layer. A pixel electrode is formed on the surface of the organic insulating film 16. The pixel electrode includes a transmissive pixel electrode 17 that transmits light from the backlight 30 and displays an image, and a reflective pixel electrode 18 that reflects external light and displays an image.

  The transmissive pixel electrode 17 is formed on the multi-gap hole 19 of the organic insulating film 16. The reflective pixel electrode 18 is formed on the organic insulating film 16 provided with the uneven pattern. The multi-gap hole 19 in the frame portion 104 is arranged avoiding the drive circuit and the wiring pattern 32. An alignment film (not shown) is formed on the surfaces of the transmissive pixel electrode 17 and the reflective pixel electrode 18.

  On the other hand, the counter substrate 200 has an insulating substrate 21 such as a glass substrate like the array substrate 100, and a red colored layer 22R, a green colored layer 22G, and a blue colored layer 22B are formed on the surface of the display region 102, A light shield 35 is formed on the surface of the frame portion 104. Further, a counter electrode 23 is formed so as to cover the red colored layer 22R, the green colored layer 22G, the blue colored layer 22B, and the light shielding body 35. An alignment film (not shown) is formed on the surface of the counter electrode.

  Further, in order to keep the distance between the array substrate 100 and the counter substrate 200 constant, columnar spacers 25 are disposed between the two substrates. The columnar spacer 25 is formed using the flat portion 36 on the organic insulating film 16 as a base so that the display area 102 and the frame portion 104 have the same height.

  The array substrate 100 and the counter substrate 200 configured as described above are disposed to face each other at a predetermined interval, and are further bonded together by a sealing material 31 formed so as to surround the periphery of both substrates. A liquid crystal layer 13 is further injected between the two substrates to fill the inside. In addition, films 26 and 27 made of a polarizing plate and a retardation plate are attached to the outside of the array substrate 100 and the counter substrate 200, respectively.

  According to the above configuration, since the multi-gap hole 19 of the frame portion 104 is arranged avoiding the drive circuit and the wiring pattern 32, even if a crack occurs in the interlayer insulating film 33, the drive circuit and the wiring The etchant does not touch the pattern 32 and corrosion does not occur.

<Second Embodiment>
FIG. 3 shows a schematic cross-sectional view when the second embodiment of the present invention is applied to FIG. 1 already shown. In the second embodiment shown in FIG. 3, since the width of the drive circuit of the frame portion 104 and the wiring pattern 40 is relatively large, the multi-gap holes 41 having the same area density are formed in the display region 102 and the frame portion 104. In this case, the multi-gap hole 41 is inevitably formed on the drive circuit or the wiring pattern 40.

  In this case, the protective pattern 42 is formed on the multi-gap hole 41 in the same layer as the transmissive pixel electrode 17. The rest is the same as the first embodiment. With such a configuration, the protective pattern 42 closes the crack generated in the interlayer insulating film 33, so that the etchant does not penetrate into the multi-gap hole 19 of the frame portion 104, and therefore the wiring pattern 40 is not corroded. Here, for the sake of explanation, an example in which the protective pattern 42 on the multi-gap hole 41 is formed by the transmissive pixel electrode 17 has been shown. However, the present invention is not limited to this. You may form both with the reflective pixel electrode 18. FIG. Further, not only the wide wiring pattern 40 but also the wiring pattern 32 shown in the first embodiment, for example, is similarly effective when arranged under the multi-gap hole 19.

<Third Embodiment>
FIG. 4 is a cross-sectional view for explaining the third embodiment of the present invention. FIG. 4 shows a state in which the organic insulating film 16 is left blocked in the multi-gap hole 19 portion of the frame portion 104 in the cross-sectional view shown in FIG. This structure can be realized by removing the unnecessary portion of the organic insulating film 16 by a half-etching process when the multi-gap hole 19 is formed in each of the frame portion 104 and the display region 102. According to this half-etching process, a multi-gap hole applied to the frame portion 104 can be obtained by reducing the etching time only to a portion corresponding to the frame portion 104 (about half) while being the same as the normal etching step. 19 can be blocked by the organic insulating film 16.

  In this manner, the multi-gap hole 19 under the frame portion 104 is closed by the organic insulating film 16, so that the etchant does not penetrate. Even if a minute crack is generated in the interlayer insulating film 33, it is blocked by the organic insulating film 16, so that it is possible to prevent the etchant from permeating into the crack and reaching the underlying wiring pattern 32 to be corroded. . The same effect can be obtained even when the wide wiring pattern 40 shown in the second embodiment is disposed below the multi-gap hole 19.

<Fourth embodiment>
FIG. 5 shows the structure of the display area 102 and the frame portion 104 of the liquid crystal display device according to the fourth embodiment to which the present invention is applied. A drive circuit and a wiring pattern 32 (not shown) are arranged on the frame portion 104. An upper organic insulating film 16 and a lower interlayer insulating film 33 are formed so as to cover these wiring patterns 32 and the like. Apart from the multi-gap concave pattern, the surface of the organic insulating film 16 is provided with a concave-convex pattern for improving the viewing angle characteristics during reflective display. In the organic insulating film 16, the multi-gap hole 19 is opened to a depth reaching the lower interlayer insulating film 33 as a concave pattern for making a difference in the thickness of the liquid crystal layer 13.

  On the organic insulating film 16, columnar spacers 25 are arranged to keep a constant interval between which the liquid crystal layer 13 is sandwiched. The columnar spacer 25 is formed using the flat portion 36 of the organic insulating film 16 as a base. A multi-gap hole 19 similar to that of the display region 102 is disposed on the organic insulating film 16 in the frame portion 104. However, the multi-gap hole 19 is filled with the columnar spacer 25 in the completed cross-sectional structure of the frame portion 104. This is a feature of this embodiment.

  In the structure according to the fourth embodiment, since the multi-gap hole 19 of the frame portion 104 is completely filled with the columnar spacer 50, even if a minute crack is generated in the interlayer insulating film 33, the columnar spacer 50 Since it is blocked, the etchant does not soak into the crack, and the drive circuit and the wiring pattern 32 disposed below the etchant are not corroded, so that a high yield can be obtained. Further, the same effect can be obtained when the wide wiring pattern 40 shown in the second embodiment is disposed under the multi-gap hole 19.

The external appearance top view for demonstrating the liquid crystal display device by the 1st-4th embodiment which concerns on this invention is shown. FIG. 1 is a schematic sectional view for explaining the structure of the liquid crystal display device according to the first embodiment of the present invention. In order to explain the structure of the liquid crystal display device according to the second embodiment of the present invention, a schematic sectional view is shown. In order to explain the structure of the liquid crystal display device according to the third embodiment of the present invention, a schematic sectional view is shown. A schematic cross-sectional view is shown to explain the structure of a liquid crystal display device according to a fourth embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Liquid crystal display panel 13 Liquid crystal layer 16 Organic insulating film 17 Transparent pixel electrode 18 Reflective pixel electrode 19 Multigap hole 25, 50 Columnar spacer 30 Backlight unit 32 Wiring pattern 33 Interlayer insulating film 100 Array substrate 102 Display area 104 Frame part 200 Opposite substrate

Claims (3)

A plurality of signal lines and a plurality of scanning lines arranged in a matrix, switching elements arranged at intersections of the signal lines and the scanning lines, and arranged to cover the signal lines, the scanning lines, and the switching elements. A transparent insulating film layer, a display region having a plurality of pixel electrodes electrically connected to each of the switching elements through through holes formed in the transparent insulating film layer, and a periphery of the display region. An array substrate on which a driving circuit for supplying a signal to the display area and a frame portion having wiring are formed;
A counter substrate on which a counter electrode facing the pixel electrode is formed;
A liquid crystal layer filled between the two substrates,
The pixel electrode includes a reflective pixel electrode that reflects external light and displays an image, and a transmissive pixel electrode that transmits backlight and displays an image.
In order to make the thickness of the liquid crystal layer different between the reflective pixel electrode and the transmissive pixel electrode, a concave pattern is formed in the transparent insulating film layer under the transmissive pixel electrode,
In the liquid crystal display device in which the concave pattern having an area density equivalent to the display area is formed in the frame portion,
2. A liquid crystal display device according to claim 1, wherein the concave pattern of the frame portion is arranged avoiding the drive circuit and the wiring. The concave pattern of the frame portion is
The liquid crystal display device according to claim 1, wherein the bottom of the concave pattern is disposed between the wirings in a plan view. The concave pattern of the frame portion is
The liquid crystal display device according to claim 1, wherein the transparent insulating film layer is interposed between the concave pattern and the wiring.

Images