JP2010152171A - Liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce a wiring capacity and to achieve high definition and frame reduction of a liquid crystal display device. <P>SOLUTION: The liquid crystal display device includes a liquid crystal panel 1 which includes an array substrate 2 having switching elements 12 arranged intersections between scanning lines and signal lines, pixel electrodes arranged like a matrix and driven by the switching elements and holding capacities for holding applied voltages of the pixel electrodes, and a counter substrate 3 having a counter electrode and disposed so as to face the array substrate 2 with a prescribed space therebetween and has a liquid crystal layer enclosed between the array substrate 2 and the counter substrate 3. At least a part (for example, holding capacity wiring 13 and drawn wiring 41 of a frame region) of power supply wiring and electric signal wiring on the array substrate 2 has a structure wherein an insulating color layer (blue insulating color layer 21) having a low dielectric constant is laminated on wiring. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a liquid crystal display device, and more particularly to a technique for reducing wiring capacitance.

  Since a liquid crystal display device is a flat display device having excellent characteristics such as thinness, light weight, and low power consumption, it is a mobile device such as a so-called PDA or a mobile phone, a display unit of a personal computer, and a liquid crystal television. It is used for a wide range of applications.

  The liquid crystal display device includes a liquid crystal display panel having a structure in which a liquid crystal layer is sandwiched between a pair of display panel substrates, that is, an array substrate and a counter substrate, and is selected for each pixel between the array substrate and the counter substrate. In addition, the liquid crystal layer is controlled by applying a voltage to display an image. Here, for example, in an active matrix liquid crystal display panel, thin film transistors (TFTs) are formed as switching elements using amorphous silicon or polysilicon semiconductor on an array substrate, and pixel electrodes and scanning lines connected to the switching elements. , Signal lines and the like are formed. On the other hand, a counter electrode made of indium tin oxide (ITO) or the like, a color filter, or the like is formed on the counter substrate.

  In this type of liquid crystal display device, a light shielding layer is provided in a panel frame area outside the display area of the array substrate, thereby preventing light leakage in the frame area (see, for example, Patent Document 1). ).

In the invention described in Patent Document 1, a first substrate having a pixel electrode connected to each intersection of a matrix wiring composed of a plurality of row electrodes and a plurality of column electrodes via a non-linear element, and a counter electrode are formed. In a display device in which a layer of an electric / light modulating material is sandwiched between a second substrate and the region excluding the pixel electrode, the region is covered with an insulating light shielding film. By providing the insulating light shielding film directly on the substrate having the matrix wiring, it is possible to obtain a sufficient light shielding effect while solving the problem of the interlayer short circuit.
JP-A 63-64023

  By the way, in recent liquid crystal display panels, high definition and multi-selection have been promoted, and the time for writing one pixel tends to be short. In addition, the resistance of the wiring tends to increase due to narrowing of the frame and high definition. From such a situation, for example, due to a lack of a writing period, a delay of a gate pulse or a decrease in the storage capacitor (Cs) potential occurs, and so-called vertical streak defect occurs.

  As described above, when the structure in which the light shielding layer is provided in the panel frame area outside the display area of the array substrate, the insulating light shielding is provided on the power supply line and the electric signal line drawn from the external connection terminal part (OLB terminal part). Although the films are stacked, the conventional insulating light-shielding film cannot reduce the storage capacity, for example, and cannot suppress the occurrence of the vertical stripe defect.

  The present invention has been proposed in view of such a conventional situation, and can reduce the wiring capacity, prevent occurrence of vertical stripe defects, and realize high definition and narrow frame. An object of the present invention is to provide a liquid crystal display device that can be used.

  In order to achieve the above object, a liquid crystal display device according to the present invention includes switching elements arranged at intersections of scanning lines and signal lines arranged in directions orthogonal to each other, and driven by the switching elements arranged in a matrix. An array substrate having a pixel electrode, a storage capacitor for holding a voltage applied to the pixel electrode, and a counter substrate having a counter electrode disposed to face the array substrate at a predetermined interval, A liquid crystal display device in which a liquid crystal layer is sealed between the array substrate and the counter substrate, and at least a part of the power supply wiring and electric signal wiring of the array substrate is an insulating colored layer having a low dielectric constant on the wiring It is characterized by having a laminated structure.

  An insulating light-shielding film used for shielding a frame region, a black matrix, or the like has a dielectric constant higher than that of, for example, an RGB insulating colored layer used for a color filter layer. In the liquid crystal display device of the present invention, an insulating colored layer having a low dielectric constant equivalent to that of the color filter layer is used as a light shielding film that overlaps with wiring such as Cs wiring or a light shielding film formed on the wiring in the frame region. Therefore, the wiring capacity is reduced.

  According to the liquid crystal display device of the present invention, for example, even when the wiring resistance increases due to narrowing of the frame or high definition, it is possible to reduce the wiring capacity and suppress the occurrence of vertical stripe defects and the like. . Therefore, according to the present invention, it is possible to realize a liquid crystal display device having a high definition and a narrow frame as compared with a conventional liquid crystal display device.

  Hereinafter, embodiments of a liquid crystal display device to which the present invention is applied will be described in detail with reference to the drawings.

  First, a schematic configuration of the liquid crystal display device will be described. As shown in FIG. 1, the liquid crystal display device includes a liquid crystal display panel 1 including an array substrate 2 and a counter substrate 3, and a liquid crystal layer LQ between the array substrate 2 and the counter substrate 3 is disposed on the array substrate 2. An image is displayed by driving the thin film transistor (pixel transistor) formed as a switching element.

  Here, in the display area which is a display unit, pixel electrodes are formed in a matrix corresponding to each pixel on the array substrate 2, and scanning lines are formed along the row direction of the pixel electrodes in the column direction. A signal line is formed along the line. Further, the pixel transistor is formed at the intersection of each scanning line and signal line.

  On the other hand, in the peripheral area of the array substrate 2 (the frame area of the liquid crystal display panel 1), a signal line drive circuit 4 that supplies drive signals to the signal lines arrayed on the array substrate 2 and a drive signal is supplied to the scanning lines. A driving circuit such as the scanning line driving circuit 5 is formed. These drive circuits are composed of a plurality of thin film transistors and wirings connected to these thin film transistors.

  FIG. 2 shows an example of a schematic circuit structure of the liquid crystal display device. As described above, the liquid crystal display device includes the liquid crystal display panel 1, and further includes an external control circuit 11 that controls the liquid crystal display panel 1. The liquid crystal display panel 1 has a structure in which the liquid crystal layer LQ is held between a pair of display panel substrates, that is, the array substrate 2 and the counter substrate 3, and the external control circuit 11 is connected to the liquid crystal display panel 1 in this example. Arranged on a separate circuit board.

  The array substrate 2 includes m × n pixel electrodes PE arranged in a matrix, m scanning lines Y (Y1 to Ym) formed along a row of the plurality of pixel electrodes PE, and each pixel electrode PE. Each of the n signal lines X (X1 to Xn), the signal lines X1 to Xn, and the scanning lines Y1 to Ym, which are formed along the column, are arranged at intersections (intersections) of m. A scanning line driving circuit 5 for driving the switching capacitors 12, the holding capacitors Cs and Cs wirings 13 arranged in parallel to the scanning lines Y1 to Ym and capacitively coupled to the pixel electrodes PE of the corresponding rows, and the scanning lines Y1 to Ym, respectively. And a signal line drive circuit 4 for driving the signal lines X1 to Xn, and a plurality of external connection pads OLB used for connection between the external control circuit 11 and the array substrate 2.

  The counter substrate 3 includes a single counter electrode CE that is arranged to face the m × n pixel electrodes PE and is set to the common potential Vcom. This common potential Vcom is also applied to the storage capacitor wiring 13, for example.

  The external control circuit 11 receives a digital video signal and a synchronization signal supplied from a processing circuit such as a mobile device, and generates a pixel display signal Vpix, a vertical scanning control signal YCT, and a horizontal scanning control signal XCT. The vertical scanning control signal YCT is supplied to the scanning line driving circuit 3, and the horizontal scanning control signal XCT is supplied to the signal line driving circuit 4 together with the display signal Vpix. The scanning line driving circuit 5 is controlled by the vertical scanning control signal YCT so as to sequentially supply the scanning signal to the scanning lines Y1 to Ym every vertical scanning (frame) period. The signal line driving circuit 4 performs serial-parallel conversion on the digital video signal input in one horizontal scanning period (1H) driven by the scanning signal, and further converts the display signal Vpix converted from digital to analog into the signal lines X1 to X1 in analog form. It is controlled by a horizontal scanning control signal XCT so as to be supplied to Xn.

  In this liquid crystal display device, the liquid crystal layer LQ is partitioned into m × n display pixels PX corresponding to the m × n pixel electrodes PE, and each display pixel PX includes two adjacent scanning lines Y and two. Between the two adjacent signal lines X. The display screen is constituted by these m × n display pixels PX. As shown in FIGS. 1 and 2, the scanning line driving circuit 5 and the signal line driving circuit 4 are arranged outside the m × n display pixels PX, and the plurality of external connection pads OLB are arranged on the periphery of the array substrate 2. Be placed. The signal line driving circuit 4 is disposed inside these external connection pads OLB. Each switching element 12 samples the display signal Vpix from the corresponding signal line X in response to the scanning signal from the corresponding scanning line Y and applies it to the corresponding pixel electrode PE, and the potential of the pixel electrode PE and the potential of the counter electrode CE. The light transmittance of the corresponding display pixel PX is controlled on the basis of the potential difference between them.

  The above is the basic configuration of the liquid crystal display device. In the liquid crystal display device according to the present embodiment, in a part of the wiring (power supply wiring and electric signal wiring) formed on the array substrate, insulation with a low dielectric constant is provided on the wiring. It has a structure in which a colored layer is laminated.

  For example, the wiring part of the storage capacitor wiring 13 will be described as an example. Conventionally, the outside of the pixel area is coated with an insulating black colored layer (insulating light shielding layer) including the storage capacitor wiring 13 for light shielding. In general, however, in the liquid crystal display device of this embodiment, a blue insulating colored layer is formed on the storage capacitor wiring 13 for supplying power to the storage capacitor Cs.

  3 is an enlarged view of the wiring portion of the storage capacitor wiring 13, and FIG. 4 is a cross-sectional view taken along line xx of FIG. In the liquid crystal display device of the present embodiment, a color filter layer is formed on the array substrate 2, and accordingly, a red insulating colored layer (R) and a green insulating colored layer (G) are formed in the pixel area of the array substrate 2. A stripe pattern of the blue insulating colored layer (B) is formed. Then, a blue insulating colored layer 21 is formed on the storage capacitor wiring 13 so as to be laminated, and a black insulating light shielding layer 22 is formed around the storage capacitor wiring 13.

  Here, supplementing the arrangement relationship between the blue insulating colored layer 21 and the black insulating light shielding layer 22, the blue insulating colored layer 21 covering the storage capacitor wiring 13 and the black insulating light shielding light in the arrangement diagram of FIG. The relationship of the layers 22 is not a multi-layer structure, but is composed of one layer each. That is, the black insulating light-shielding layer 22 is formed in a portion excluding the wiring portion of the storage capacitor wiring 13 to form a black frame, and the blue insulating colored layer 21 is laminated on the wiring portion of the storage capacitor wiring 13 to form a blue frame. Is configured.

  Since the storage capacitor wiring 13 is formed of a metal wiring, it has a light shielding property, and light is not transmitted even when the blue insulating colored layer 21 is formed. It is preferable to form the blue insulating colored layer 21 on the storage capacitor wiring 13 in the pixel area. However, since the wiring is thin, it is actually difficult to perform the coloring process.

As described above, the wiring capacity of the storage capacitor wiring 13 can be reduced by forming the blue insulating colored layer 21 on the storage capacitor wiring 13. Comparing the dielectric constants of the colored layers used in the color filter layer and the black insulating light-shielding layer, the color filter layer has a lower dielectric constant than the black insulating light-shielding layer in any color as described below.
Red (R) ≦ 4.3
Green (G) ≦ 4.6
Blue (B) ≤ 4.3
Black (BK) ≤ 6.0
BK ≧ G ≧ R = B

  Therefore, the wiring capacity of the storage capacitor wiring 13 can be reduced compared to the case where the black insulating light-shielding layer is formed, regardless of which of the red, green, and blue insulating colored layers is used. In the present embodiment, the reason why the blue insulating colored layer 21 is formed on the storage capacitor wiring 13 is that the most difficult material to reflect among the three primary colors is blue, which is effective in preventing unnecessary reflection. That's why. If the reflectivity is not taken into consideration, other (red or green) colorants may be used. In either case, the dielectric constant is lower than that of the black insulating light-shielding layer 22, and the same effect as that of the blue insulating colored layer 21 can be obtained.

  In this embodiment, the color filter layer is formed on the array substrate 2, but by providing the color filter layer on the array substrate 2, the blue insulating colored layer can be formed simultaneously with the color filter layer formation. This is advantageous in terms of manufacturing. A color filter layer may be provided on the counter substrate 3 side, and an insulating colored layer having the same color as one of them may be formed on the array substrate side, or a transparent transparent insulating layer having a low dielectric constant May be formed on the array substrate side as an insulating colored layer. However, when the transparent insulating layer is formed as an insulating colored layer on the array substrate side, it is necessary to consider light shielding properties.

  Furthermore, the blue insulating colored layer can be formed not only on the storage capacitor wiring 13 but also in the frame region of the array substrate 2, for example. For example, in the example shown in FIG. 5, in the frame area around the display area of the array substrate 2, the insulating light shielding layer 22 for shielding the light of the backlight is formed along the outer periphery of the display area, and on the outside thereof. A blue insulating colored layer 21 is formed.

  FIG. 5 is a plan view showing the vicinity of the frame region of the liquid crystal display panel. In order from the top in the drawing, a pixel portion (display region) 31 and a signal line driving circuit forming region 32 which is a switching circuit portion of a multi-select circuit. A lead-out wiring region 33 from which power supply lines / electrical signal lines are drawn out and an external connection pad (OLB) formation region 34 are formed. In the conventional liquid crystal display device, the signal line driving circuit formation region 32 to the lead-out wiring region 33 are generally covered with a black insulating light shielding layer. In the case of this example, the signal line drive circuit formation region 32 and the lead-out wiring region 33 close to the pixel portion 31 are covered with the black insulating light shielding layer 22, but the light away from the pixel portion 31 in the lead-out wiring region 33. The region where the film cannot be removed is covered with the blue insulating colored layer 21.

  In a liquid crystal display panel, it is normal to place a bezel on the outside, and a region closer to the bezel than a position where light is emitted obliquely from a gap between the bezel and the liquid crystal display panel is a region where light cannot escape. . Therefore, the blue insulating colored layer 21 is formed in the lead-out wiring region 33 closer to the bezel than the position, and is arranged so that the light passing through the blue insulating colored layer 21 does not leak outside. Not only the lead-out wiring region 33 near the bezel, but also the portions that are shielded from light by a module such as a light-shielding tape or bezel, as described above, have a low dielectric constant blue (red, green) insulation to reduce wiring capacitance. It is possible to form a colored layer.

  Further, as shown in FIG. 6A, the portion that is not shielded from light by the module has a blue insulating colored layer 21 and a black color on the lead-out wiring 41 that is led out from the OLB formation region such as the power supply line and the electric signal line. The insulating light shielding layers 22 can be alternately formed in stripes, or the blue insulating colored layers 21 can be formed in a checkered pattern as shown in FIG. 6B.

It is a perspective view which shows schematic structure of a liquid crystal display panel. It is a circuit diagram which shows an example of the drive circuit of an array board | substrate. It is a schematic plan view which expands and shows the pixel area vicinity. It is a schematic sectional drawing in the xx line | wire of FIG. It is a schematic plan view which shows the frame area | region vicinity of a liquid crystal display panel. (A) is a schematic plan view which shows the example which formed the blue insulating colored layer and the black insulating light shielding layer in stripe form, (b) shows the example which formed the blue insulating colored layer in checkered pattern shape. It is a schematic plan view.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Liquid crystal display panel, 2 Array substrate, 3 Opposite substrate, 4 Signal line drive circuit, 5 Scan line drive circuit, 11 External control circuit, 12 Switching element, 13 Holding capacity wiring, 21 Blue insulating colored layer, 22 Black insulating property Light-shielding layer, 31 pixel portion, 32 signal line drive circuit formation region, 33 lead-out wiring region, 34 external connection pad (OLB) formation region, 41 lead-out wiring

Claims (6)

Switching elements arranged at intersections of scanning lines and signal lines arranged in directions orthogonal to each other, pixel electrodes arranged in a matrix and driven by the switching elements, and for holding a voltage applied to the pixel electrodes An array substrate having a storage capacity;
A counter substrate having a counter electrode disposed opposite to the array substrate at a predetermined interval;
A liquid crystal display device in which a liquid crystal layer is sealed between the array substrate and the counter substrate,
At least a part of the power supply wiring and the electric signal wiring of the array substrate has a structure in which an insulating coloring layer having a low dielectric constant is laminated on the wiring.   The storage capacitor wiring for supplying power to the storage capacitor has a structure in which an insulating colored layer having a low dielectric constant is laminated on the wiring, and an insulating light-shielding layer is provided in a portion where the storage capacitor wiring is not formed. The liquid crystal display device according to claim 1, wherein the liquid crystal display device is formed.   In the frame area around the display area of the array substrate, an insulating light shielding layer for shielding light from the backlight is formed along the outer periphery of the display area, and an insulating colored layer is formed outside the insulating light shielding layer. The liquid crystal display device according to claim 1.   The insulating light-shielding layer and the insulating colored layer for shielding light from a backlight are formed in a stripe shape or a checkered pattern in a frame region around the display region of the array substrate. 1. A liquid crystal display device according to 1.   5. The liquid crystal display device according to claim 1, wherein the insulating colored layer is the same as any one of the color filter layers.   6. The liquid crystal display device according to claim 5, wherein the insulating colored layer is the same as the blue color filter layer.

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