JP2011027951A - Liquid crystal display panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase dielectrics other than a liquid crystal layer of a subpixel for view angle control in a liquid crystal display panel having the subpixel for view angle control for easing steepness of TV characteristics and bringing them close to those of a subpixel for display to achieve easy gradation display and reduction in cost. <P>SOLUTION: In the liquid crystal display panel 10A including a first substrate AR and a second substrate CF arranged face to face while putting the liquid crystal layer LC between them, the subpixel 14A for display and the subpixel 15A for view angle control are arranged adjacently to each other for each pixel. In the subpixel 15A for view angle control, a pair of electrodes 25 and 30A are formed, and a pair of alignment layers 27 and 34 putting the liquid crystal layer LC between the pair of electrodes 25 and 30A are formed. In the subpixel 15A for view angle control, a dielectric film formed of an overcoat layer 33 different from the liquid crystal layer LC and the alignment layers 27 and 34 is formed between the pair of electrodes 25 and 30A. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

The present invention relates to a liquid crystal display panel including a viewing angle control subpixel, and more particularly, a viewing angle control characteristic in which a dielectric different from a liquid crystal layer is formed between a pair of electrodes of a viewing angle control subpixel. It relates to a good liquid crystal display panel.

Liquid crystal display panels are characterized by their light weight, thinness, and low power consumption compared to CRTs (cathode ray tubes), and are therefore used in many electronic devices for display purposes. The liquid crystal display panel displays an image by changing the direction of liquid crystal molecules aligned in a predetermined direction by an electric field and changing the amount of light transmitted through the liquid crystal layer. In such a liquid crystal display panel, a reflection type in which external light is incident on the liquid crystal layer, is reflected by the reflector, is transmitted through the liquid crystal layer again, and is incident on the liquid crystal layer. There are a transmission type that transmits light and a transflective type that includes both.

As a method of applying an electric field to a liquid crystal layer of a liquid crystal display panel, a vertical electric field type and a horizontal electric field type are known. A vertical electric field type liquid crystal display panel applies a substantially vertical electric field to liquid crystal molecules by a pair of electrodes arranged with a liquid crystal layer interposed therebetween. This vertical electric field type liquid crystal display panel includes TN (Twisted Nematic) mode, VA (Vertical Alignment).
) Mode, MVA (Multi-domain Vertical Alignment) mode, and the like are known. A horizontal electric field type liquid crystal display panel is provided with a pair of electrodes insulated from each other on one inner surface side of a pair of substrates disposed with a liquid crystal layer interposed therebetween, and a substantially horizontal electric field is applied to liquid crystal molecules. To be applied. As this horizontal electric field type liquid crystal display panel, there are known an IPS (In-Plane Switching) mode in which a pair of electrodes do not overlap in a plan view and an FFS mode in which they overlap.

Of these, the IPS mode liquid crystal display panel is formed in a comb-like shape so that a pair of electrodes composed of a pixel electrode and a common electrode are engaged with each other while being electrically insulated from each other. In the meantime, a horizontal electric field is applied to the liquid crystal. The IPS mode liquid crystal display panel has an advantage that the viewing angle is wider than that of the vertical electric field type liquid crystal display panel.

In addition, the FFS mode liquid crystal display panel has a pair of electrodes each including a common electrode and a pixel electrode disposed in different layers with an insulating film interposed therebetween, and a slit-like opening is provided in the common electrode or the pixel electrode on the liquid crystal layer side. A substantially horizontal electric field passing through the slit-shaped opening is applied to the liquid crystal layer. The FFS mode liquid crystal display panel is widely used in recent years because it can obtain a wide viewing angle and improve image contrast. In this FFS mode liquid crystal display panel, a common electrode and a pixel electrode are formed on the same plane as a thin film transistor TFT (Thin Film Transistor) as a switching element, and a common electrode and a pixel electrode are both TFTs. It is known that it is arranged above the top.

Among these, the FFS mode liquid crystal display panel in which the common electrode and the pixel electrode are both disposed above the TFT is coated with an interlayer resin film on the surface of the TFT, etc., and an interelectrode insulating film is formed on the surface of the interlayer resin film. A lower electrode made of a transparent conductive material and an upper electrode having a slit-like opening are formed. Both the upper electrode and the lower electrode can be operated as either a pixel electrode or a common electrode.

As described above, the horizontal electric field type liquid crystal display panel has a wide viewing angle. However, when displaying confidential information, a narrow viewing angle is desirable in order to prevent others from seeing. Therefore, as shown in Patent Documents 1 to 3 below, a viewing angle control sub-pixel is provided adjacent to the display sub-pixel so that the viewing angle can be appropriately narrowed when necessary. Liquid crystal display panels are known. This viewing angle control sub-pixel narrows the viewing angle by applying an electric field different from that of the display sub-pixel to the liquid crystal molecules to change the orientation of the liquid crystal molecules. The liquid crystal of the display subpixel and the viewing angle control subpixel are of the same type, and the display subpixel includes a VA mode (see Patent Document 2 below), an IPS mode (see Patent Document 1 below), and FFS.
A mode (see Patent Document 3 below) or the like is possible.

JP 2007-156403 A JP 2007-178948 A JP 2007-178879 A

However, in the conventional viewing angle control sub-pixel, the dielectric disposed between the pair of electrodes to which the driving voltage is applied is only the pair of alignment films other than the liquid crystal layer. The thickness of the alignment film is about 5
Since the driving voltage applied between the pair of electrodes is mostly applied to the liquid crystal layer, the luminance characteristic with respect to the driving voltage of the viewing angle control sub-pixel, that is, T
The V curve has a steep characteristic. For this reason, the viewing angle control sub-pixel produces a large luminance change with a slight voltage change, and it is difficult to set multi-gradation viewing angle control.

In addition, since the TV curve of the viewing angle control sub-pixel is greatly different from the TV curve of the display sub-pixel, the driving voltage of the viewing angle control sub-pixel is different from that of the display sub-pixel. It could not be the same as the driving voltage. Therefore, in a liquid crystal display panel having a conventional viewing angle control subpixel, it is necessary to generate a driving voltage for the viewing angle control subpixel separately from the generation of the driving voltage for the display subpixel. Two DA conversion circuits, one for display sub-pixels and one for viewing angle control sub-pixels, are required, causing a problem of increasing the price. Further, in a liquid crystal display panel having a conventional viewing angle control subpixel, the electrode of the viewing angle control subpixel and the electrode of the display subpixel cannot be electrically connected to each other. There is a problem that the area of the frame region formed on the frame cannot be reduced.

Further, in a liquid crystal display panel having a conventional viewing angle control subpixel, the gradation table of the viewing angle control subpixel is different from the gradation table of the display subpixel. When performing gradation display, a separate gradation table is required, which increases the storage capacity.

The present invention has been made to solve the above-described problems of the prior art, and in a liquid crystal display panel having a viewing angle control subpixel, the TV characteristics of the viewing angle control subpixel are steep. The change can be relaxed to approximate the TV characteristics of the display sub-pixel, and the gradation viewing angle control can be easily performed, and the same gradation table as the display sub-pixel can be used. An object of the present invention is to provide a liquid crystal display panel.

In order to achieve the above object, a liquid crystal display panel according to the present invention has a first substrate and a second substrate that are opposed to each other with a liquid crystal layer interposed therebetween, and a display subpixel and a viewing angle control subpixel are arranged. And
The viewing angle control sub-pixel includes a pair of electrodes composed of an electrode formed on the first substrate and an electrode formed on the second substrate, and a pair of orientations sandwiching the liquid crystal layer between the pair of electrodes. A liquid crystal display panel in which a film is formed, wherein the viewing angle control sub-pixel is a vertical electric field method,
A dielectric film different from the liquid crystal layer and the alignment film is formed between the pair of electrodes.

In the liquid crystal display panel of the present invention, a dielectric film different from the liquid crystal layer and the alignment film is formed between the pair of electrodes of the vertical electric field type viewing angle control sub-pixel. Thereby, in the viewing angle control sub-pixel, the voltage applied between the pair of electrodes is divided by the newly applied dielectric film, so that the applied voltage directly applied to the liquid crystal layer is lowered. . Therefore, according to the liquid crystal display panel of the present invention, the steepness of TV characteristics is alleviated and the viewing angle can be controlled in gradation. One viewing angle control sub-pixel may be formed for each pixel.
A pixel having a viewing angle control sub-pixel and a pixel having no viewing angle control sub-pixel may be mixed.

In the liquid crystal display panel of the present invention, the viewing angle control sub-pixel has a capacitance due to the liquid crystal layer between the pair of electrodes as C1, and a capacitance due to a dielectric film other than the liquid crystal layer as C2.
When
C2 / C1 ≧ 0.5
It is preferable that the relationship is satisfied.

When such a condition is satisfied, a steep relaxation effect of the TV characteristics of the viewing angle control sub-pixels appears greatly. Note that the maximum value of C2 / C1 varies depending on the value of the voltage applied between the pair of electrodes of the viewing angle control subpixel, but the capacitance C due to the dielectric film other than the liquid crystal layer.
If 2 is too large, the voltage applied to the liquid crystal layer becomes small, and the viewing angle control effect begins to deteriorate. For example, when Vall ≦ 6V and VLc ≧ 1, C2 / C1 ≦ 5 is optimal.

In the liquid crystal display panel of the present invention, at least one of a resin film and an inorganic insulating film is formed on the display subpixel, and a dielectric film of the viewing angle control subpixel is formed on the display subpixel. Preferably, it is made of the same material as at least one of the resin film and the inorganic insulating film.

The resin film or inorganic insulating film formed on the display subpixel is the dielectric film itself.
Therefore, according to the liquid crystal display panel of the present invention, the dielectric film of the viewing angle control sub-pixel is formed at the same time as the display sub-pixel is formed without providing the dielectric film forming step of the viewing angle control sub-pixel. Will be able to.

In the liquid crystal display panel of the present invention, the display subpixel operates in an IPS mode in which a pair of electrodes for applying an electric field to liquid crystal molecules of the liquid crystal layer is formed on the first substrate. Can do.

According to the liquid crystal display panel of the present invention, since the display sub-pixel operates in the IPS mode, a wide viewing angle can be obtained, and the effect of providing the viewing-angle control sub-pixel is remarkably exhibited.

In the liquid crystal display panel of the present invention, the display subpixel operates in an FFS mode in which a pair of electrodes for applying an electric field to liquid crystal molecules of the liquid crystal layer is formed on the first substrate. The inorganic insulating film may be made of the same material as the interelectrode insulating film formed between the pair of electrodes of the display subpixel.

According to the liquid crystal display panel of the present invention, since the display sub-pixel is operated in the FFS mode, a wide viewing angle can be obtained and the effect of providing the viewing-angle control sub-pixel is remarkably exhibited. In addition, in the FFS mode liquid crystal display panel, an inorganic insulating film (also referred to as an interelectrode insulating film) made of silicon nitride or silicon oxide is formed between the upper electrode and the lower electrode.
Therefore, according to the liquid crystal display panel of the present invention, the dielectric of the viewing angle control subpixel is formed simultaneously with the formation of the inorganic insulating film of the display subpixel without providing the dielectric film forming step of the viewing angle control subpixel. A body membrane can be formed.

In the liquid crystal display panel of the present invention, the resin film may be formed of the same material as the overcoat layer that covers the color filter layer.

The overcoat layer is formed to flatten the step between the color filter layers and prevent the color filter layer from leaking impurities into the liquid crystal layer, but is the dielectric layer itself. . According to the liquid crystal display panel of the present invention, the overcoat layer of the viewing angle control subpixel is formed simultaneously with the formation of the overcoat layer of the display subpixel without providing the dielectric film forming step of the viewing angle control subpixel. A dielectric film made of can be formed.

In the liquid crystal display panel of the present invention, the resin film may be formed of the same material as the color filter layer and the overcoat layer covering the color filter layer.

Since the color filter layer is a resin film in which a pigment is mixed, both the color filter layer and the overcoat layer are dielectric films themselves. Therefore, according to the liquid crystal display panel of the present invention, without providing a dielectric film forming step for the viewing angle control subpixel, the viewing angle control is performed simultaneously with the formation of the color filter layer and the overcoat layer of the display subpixel. A dielectric film composed of the color filter layer and the overcoat layer of the sub-pixel can be formed.

In the liquid crystal display panel of the present invention, it is preferable that the viewing angle control sub-pixel has a voltage-transmittance curve similar to that of the display sub-pixel.

According to the liquid crystal display panel of the present invention, the voltage-transmittance curve of the viewing angle control sub-pixel is the same as the voltage-transmittance curve of the display sub-pixel. The control gradation can be controlled by applying substantially the same voltage as the display gradation of the display sub-pixel.

In the liquid crystal display panel of the present invention, it is preferable that the viewing angle control sub-pixels share the gradation table of the display sub-pixels.

In the liquid crystal display panel of the present invention, since the voltage-transmittance curve of the viewing angle control sub-pixel is the same as the voltage-transmittance curve of the display sub-pixel, the viewing angle control sub-pixel is the display sub-pixel. The pixel gradation table can be used in common. Therefore, according to the liquid crystal display panel of the present invention, it is not necessary to separately provide a gradation table for controlling the sub-pixel for viewing angle control, so that the area of the frame area around the display area can be reduced accordingly, Moreover, the liquid crystal display panel can be manufactured at low cost.

In the liquid crystal display panel of the present invention, an electrode formed on the second substrate side of the viewing angle control sub-pixel extends over the display sub-pixel, and the display sub-pixel includes It is good to serve as a shield electrode.

According to the liquid crystal display panel of the present invention, of the pair of electrodes of the viewing angle control subpixel, the electrode formed on the second substrate side extends over the display subpixel forming one pixel. Since this electrode operates as a shield electrode, it is possible to obtain a liquid crystal display panel in which adverse effects on the display image quality are suppressed even when static electricity is applied from the outside, such as a person's finger approaching.

It is a top view which shows the outline | summary of the array substrate of 1 pixel of 1st Embodiment. It is sectional drawing of the II-II line of FIG. It is sectional drawing of the III-III line | wire of FIG. It is sectional drawing of the IV-IV line of FIG. It is sectional drawing which shows the modification of 1st Embodiment corresponding to FIG. It is sectional drawing of 2nd Embodiment corresponding to FIG. It is a top view which shows the outline | summary of the array substrate of 1 pixel of 3rd Embodiment. It is sectional drawing of the VIII-VIII line of FIG. It is sectional drawing of the IX-IX line of FIG. It is sectional drawing of the XX line of FIG. It is a figure which shows TV curve of embodiment and a prior art example.

The best mode for carrying out the present invention will be described below with reference to the embodiments and drawings. However, the embodiments shown below are not intended to limit the present invention to those described herein. The present invention can be equally applied to various modifications without departing from the technical idea shown in the claims.

Note that the “surface” of the array substrate and the color filter substrate described here indicates a surface on which various wirings are formed or a surface facing the liquid crystal. In addition, in each drawing used for the description in this specification, each layer and each member are displayed at different scales so that each layer and each member can be recognized on the drawing. However, it is not necessarily displayed in proportion to the actual dimensions.

[First Embodiment]
The configuration of the main part of the liquid crystal display panel 10A of the first embodiment will be described with reference to FIGS. The liquid crystal display panel 10A according to the first embodiment includes a color display lateral electric field type FFS mode display area 12A and a vertical electric field type viewing angle control area 13A. As shown in FIGS.
The liquid crystal layer LC is sandwiched between the array substrate AR and the color filter substrate CF. The display area 12A operates in the FFS mode, the viewing angle control area 13A operates in the VA mode, and the liquid crystal layer LC can be used in common. The liquid crystal display panel 10A has a plurality of pixels (pixels) 11A aligned in the row direction (X-axis direction in FIG. 1) and the column direction (Y-axis direction in FIG. 1). As shown in FIG. 1, one pixel 11 </ b> A has a display area 12.
A and a viewing angle control region 13A disposed adjacent to the display region 12A. The display area 12A is, for example, a display sub-pixel 14 for three-color display of R (red), G (green), and B (blue).
The color of each pixel is determined by the color mixture of these colors. Viewing angle control region 13A
Includes one viewing angle control sub-pixel 15A.

As shown in FIG. 1, the display sub-pixel 14A and the viewing angle control sub-pixel 1 of the array substrate AR.
5A includes a scanning line 16 and a common wiring 17 made of an opaque metal such as aluminum or molybdenum that extend in the X-axis direction, and a signal line made of an opaque metal such as aluminum or molybdenum that extends in the Y-axis direction. 18 and a TFT disposed in the vicinity of the intersection of the scanning line 16 and the signal line 18. The TFT of the display sub-pixel 14A and the viewing-angle control sub-pixel 1
All the 5A TFTs have the same configuration.

The array substrate AR is based on a first transparent substrate 19 made of transparent insulating glass, quartz, plastic, or the like. On the first transparent substrate 19, scanning lines 16 and common wirings 17 are formed on the side facing the liquid crystal layer LC. A gate electrode G extends from the scanning line 16. Only the display sub-pixel 14A is partially connected to the common wiring 17 to form ITO (Indi
A lower electrode 20 made of a transparent conductive material such as um Thin Oxide) or IZO (Indium Zinc Oxide) is formed. The lower electrode 20 electrically connected to the common wiring 17 is formed in a substantially totally transparent region of the display sub-pixel 14A and operates as a common electrode. A transparent gate insulating film 21 made of silicon nitride, silicon oxide or the like is laminated so as to cover the scanning line 16, the gate electrode G, and the lower electrode 20 of the display subpixel 14A. A semiconductor layer 2 made of amorphous silicon, polycrystalline silicon, or the like is formed on the gate insulating film 21 overlapping the gate electrode G in plan view.
2 is formed. A signal line 18 is formed on the gate insulating film 21. A source electrode S extends from the signal line 18, and the source electrode S is in partial contact with the surface of the semiconductor layer 22.

Further, a drain electrode D formed simultaneously with the same material as the signal line 18 and the source electrode S is provided on the gate insulating film 21, and the drain electrode D is disposed in proximity to the source electrode S and the semiconductor layer 22. Partially touching. Adjacent scanning lines 16 of the liquid crystal display panel 10A
And a region surrounded by the signal line 18 corresponds to one sub-pixel region. And the gate electrode G
The gate insulating film 21, the semiconductor layer 22, the source electrode S, and the drain electrode D constitute a TFT serving as a switching element. Further, the signal line 18, the TFT, and the gate insulating film 21
A transparent passivation film 23 made of, for example, silicon nitride, silicon oxide, or the like is laminated so as to cover the exposed portion.

In the display sub-pixel 14A, the ITO or I is covered so as to cover the passivation film 23.
An upper electrode 24 made of a transparent conductive material such as ZO is formed so as to overlap the lower electrode 20 in plan view. In the viewing angle control subpixel 15A, the first electrode 25 for viewing angle control is the same process and the same material as the upper electrode 24 so as to cover the passivation film 23, and the first electrode 25 for viewing angle control is the subpixel 1 for viewing angle control.
It is formed in a substantially totally transparent area of 5A.

In the display sub-pixel 14A, a contact hole 26 that penetrates the passivation film 23 and reaches the drain electrode D of the TFT is formed, and the upper electrode 24 is electrically connected to the drain electrode D of the TFT. Therefore, the upper electrode 24 operates as a pixel electrode. Similarly, in the viewing angle control sub-pixel 15A, the drain electrode D of the TFT penetrates the passivation film 23.
Is formed, and the viewing angle control first electrode 25 is electrically connected to the drain electrode D of the TFT. Therefore, the viewing angle control first electrode 25 operates as a pixel electrode. And so that the surface of the upper electrode 24 and the first electrode 25 for viewing angle control may be covered,
For example, a first alignment film 27 made of polyimide is laminated. The first alignment film 27 is rubbed in the Y-axis direction of FIG.

In the display sub-pixel 14 </ b> A, a “<”-shaped slit-shaped opening 28 extending in the extending direction of the signal line 18 is formed in the upper electrode 24. Since the display sub-pixel 14A is vertically long, when the slit-shaped openings 28 are extended in the horizontal direction, the number of both ends of the slit-shaped openings 28 increases. The end of the slit-shaped opening 28 becomes an abnormal alignment region of liquid crystal molecules. Therefore, in the liquid crystal display panel 10A of the first embodiment, as shown in FIG. 1, the number of ends of the slit-shaped openings 28 is reduced by setting the extending direction of the slit-shaped openings 28 to the Y-axis direction. , Reducing the decrease in aperture ratio.

The extending direction of the "<"-shaped slit-shaped opening 28 is about +5 degrees and about-with respect to the rubbing direction.
It is tilted 5 degrees. When all the slit-shaped openings 28 are inclined clockwise or counterclockwise with respect to the rubbing direction, the liquid crystal molecules are twisted in one direction, so that the color changes depending on the viewing angle direction. This is because the apparent retardation changes depending on the direction of viewing the liquid crystal molecules. In order to reduce this, in the liquid crystal display panel 10A of the first embodiment, the extending direction of the slit-shaped opening 28 is provided with a domain inclined about +5 degrees and a domain inclined about -5 degrees with respect to the clockwise direction. Although the signal line 18 is refracted in a “<” shape together with the slit-shaped opening 28, the signal line 18 itself may be formed in a straight line without being refracted. That is, the shape of the sub-pixel may be a rectangular shape that is commonly seen.

The color filter substrate CF is based on a second transparent substrate 29 made of transparent insulating glass, quartz, plastic, or the like. On the surface of the second transparent substrate 29, ITO or I
A viewing angle control second electrode 30A made of a transparent conductive material such as ZO is formed in the entire region for one pixel 11A. The viewing angle control second electrode 30A of the viewing angle control subpixel 15A operates as a common electrode, and the viewing angle control second electrode 30A of the display subpixel 14A operates as a shield electrode. In the display sub-pixel 14A, on the viewing angle control second electrode 30A,
A light shielding layer 3 made of resin or metal having a light shielding property at a position facing the scanning line 16 and the signal line 18.
1 is formed, and light of a different color for each display sub-pixel 14A (for example, R, G, B, colorless W
) Is formed.

An overcoat layer 33 made of a transparent resin material such as a photoresist so as to cover the light shielding layer 31 and the color filter layer 32 of the display sub-pixel 14A and the viewing-angle control second electrode 30A of the viewing-angle control sub-pixel 15A. Are stacked. Display sub-pixel 14A
The overcoat layer 33 is formed so as to flatten the level difference caused by the color filter layers 32 of different colors and to block impurities flowing out from the light shielding layer 31 and the color filter layer 32 from entering the liquid crystal layer LC. Yes. The overcoat layer 33 of the viewing angle control sub-pixel 15A is formed to have a dielectric function. A second alignment film 34 made of, for example, polyimide is formed so as to cover the overcoat layer 33. The second alignment film 34 is rubbed in the direction opposite to that of the first alignment film 27.

The array substrate AR and the color filter substrate CF thus formed are opposed to each other, and a sealant (not shown) is provided around both substrates so that both substrates are bonded together, and homogeneously oriented liquid crystal is placed between both substrates. By filling, the liquid crystal display panel 11A of the liquid crystal display panel 10A according to the first embodiment is obtained. A spacer (not shown) for holding the liquid crystal layer LC at a predetermined thickness is formed on the color filter substrate CF.

With the above configuration, in the display sub-pixel 14A, when the TFT is turned on, the lower electrode 2
An electric field is generated between 0 and the upper electrode 24, and the alignment of the liquid crystal molecules in the liquid crystal layer LC changes. As a result, the light transmittance of the liquid crystal layer LC changes and an image is displayed in the FFS mode. In addition, a region where the lower electrode 20 and the upper electrode 24 face each other with the passivation film 23 therebetween forms an auxiliary capacitance, and when the TFT is turned off, an electric field between the lower electrode 20 and the upper electrode 24 is predetermined. Hold for hours. Further, in the display sub-pixel 14A, the viewing angle control second electrode 30A of the color filter substrate CF operates as a shield electrode, so that a display image is generated by static electricity applied to the liquid crystal display panel 10A from the outside by a human finger or the like. Disturbance can be suppressed.

In the viewing angle control sub-pixel 15A, when the TFT is turned on, an electric field is generated between the viewing angle control first electrode 25 of the array substrate AR and the viewing angle control second electrode 30A of the color filter substrate CF. Then, the alignment direction of the liquid crystal molecules that are homogeneously aligned in the liquid crystal layer LC changes perpendicularly to the display surface. Thereby, in the viewing angle control sub-pixel 15A, an achromatic color light leakage occurs from the left-right direction, and thus the display region 12A is difficult to visually recognize from the left-right direction.
Apparently, the viewing angle of the display area 12A is narrowed.

In a conventional liquid crystal display panel that performs viewing angle control, the TV curve of the viewing angle control sub-pixel changes abruptly as shown by B1 in FIG. 11, and is greatly different from the TV curve of the display sub-pixel. . In view of this, a preferred capacity by a dielectric between both electrodes of the viewing angle control sub-pixel was examined. Note that a curve B1 in FIG. 11 shows a TV curve in a front view, and A1, B2
And B3 indicate TV curves when viewed from an oblique direction of 40 °.

The voltage of both electrodes of the viewing angle control subpixel is Vall, the voltage of the liquid crystal layer portion is VLc, the voltage of the dielectric portion other than the liquid crystal layer is Vc, the capacitance of the liquid crystal layer is C1, the capacitance of the dielectric (capacity of the alignment film) And C2)
Vall = VLc + Vc
It becomes. Considering the voltage distribution between the capacitors connected in series here,
VLc × C1 = Vc × C2
So,
Vall = VLc × (1+ (C1 / C2))
It becomes.
Here, as a result of performing an experiment by varying Vall and VLc, Vall ≧ 3V, VLc ≦ 2V
In this case, when C2 / C1 ≧ 0.5, the steep relaxation effect of the TV characteristics of the viewing angle control sub-pixels becomes significant. An example of such a result is shown by a curve B2 in FIG. In addition,
A curve A1 in FIG. 11 is a VT curve of the display pixel.

Note that C1 / C2 does not have an upper limit, and changes depending on the value of the voltage Vall applied between the pair of electrodes of the viewing angle control subpixel, but the capacitance C2 due to the dielectric film other than the liquid crystal layer If it is too large, the VLc used for liquid crystal control becomes small, and the viewing angle control effect starts to deteriorate. For example, when Vall ≦ 6 V and VLc ≧ 1, C2 / C1 ≦ 5 is appropriate. Therefore, the upper limit of C1 / C2 is preferably C1 / C2 ≦ 5 when V ≦ 6V and VLc ≧ 1.

As shown in Patent Documents 1 to 3, in the conventional sub-pixel for controlling the viewing angle of the liquid crystal display panel, there are no dielectrics other than the liquid crystal layer and the alignment film as the dielectric between the two electrodes. Since the thickness of the alignment film is as thin as 500 to 1000 mm, C1 / C2 ≧ 0.5 is not satisfied. C1 /
In order to satisfy C2 ≧ 0.5, the thickness of the dielectric other than the liquid crystal layer needs to be 5000 mm or more.

Therefore, it is necessary to add a dielectric film different from the liquid crystal layer and the alignment film between both electrodes of the viewing angle control sub-pixel. In the first embodiment described above, as this additional dielectric film, the overcoat layer 33 of the color filter substrate CF of the display subpixel 14A extends to the viewing angle control subpixel 15A. Thus, the dielectric film can be added to the viewing angle control sub-pixel 15A without separately increasing the number of steps of manufacturing the dielectric film.

In this case, as described above, it is preferable to add a dielectric film having a thickness satisfying C1 / C2 ≧ 0.5. However, even if C1 / C2 ≧ 0.5 is not satisfied, B2 in FIG. As shown in
If the TV curve of the viewing angle control subpixel is made gentler than before, the TV curve of the viewing angle control subpixel is brought closer to the TV curve of the display subpixel. In addition, C in the first embodiment
2 is the total of the capacity of the first alignment film 27, the capacity of the overcoat layer 33, and the capacity of the second alignment film 34.

In the first embodiment, the display sub-pixel 14A and the viewing angle control sub-pixel 15A are used.
The overcoat layer 33 is formed so that no step is generated between the overcoat layer 33 and the overcoat layer 33.
Is formed to have an optimum film thickness for each of the display sub-pixel 14A and the viewing-angle control sub-pixel 15A, so that a step is generated between the display sub-pixel 14A and the viewing-angle control sub-pixel 15A. There is.

[Modification of First Embodiment]
FIG. 5 is a cross-sectional view showing a liquid crystal display panel 10A ′ according to a modification of the first embodiment. FIG. 5 corresponds to FIG. 4 in the liquid crystal display panel 10A of the first embodiment. In the liquid crystal display panel 10A of the first embodiment, only the overcoat layer 33 is added as the dielectric film of the viewing angle control sub-pixel 15A. However, since the color filter layer 32 itself is a dielectric layer, the viewing angle control is performed. For example, a colorless W color filter layer 32 and an overcoat layer 33 are formed on the sub-pixel 15A. Therefore, in FIG. 4, both the display sub-pixel 14A and the viewing-angle control sub-pixel 15A are described with the surface of the overcoat layer 33 of the color filter substrate CF being flat. Overcoat layer 3
3 may be in a state where it is depressed more than the surface of the overcoat layer 33 in the display sub-pixel 14A.

Also in the liquid crystal display panel 10A ′ of the modified example of the first embodiment, the viewing angle control sub-pixel 1
Since the configuration of the 5A color filter substrate CF is the same as that of the display sub-pixel 14A, the TV curve of the viewing angle control sub-pixel 15A is replaced with the TV curve of the display sub-pixel 14A without adding a special manufacturing process. Can be approached. In addition, C2 in the modification of 1st Embodiment
Is the sum of the capacity of the first alignment film 27, the capacity of the color filter layer 32, the capacity of the overcoat layer 33, and the capacity of the second alignment film 34.

[Second Embodiment]
Next, the liquid crystal display panel 10B of 2nd Embodiment is demonstrated using FIG. 6 corresponds to FIG. 4 in the liquid crystal display panel 10A of the first embodiment, but the liquid crystal display panel 10B of the second embodiment also corresponds to FIGS. 1 to 3 in the liquid crystal display panel 10A of the first embodiment. Since the configuration is the same, the illustration is omitted. Further, the liquid crystal display panel 10B of the second embodiment.
In the first embodiment, the same reference numerals are assigned to the same components as those of the liquid crystal display panel 10A of the first embodiment, and the reference numerals having subscripts are changed to “B”. Omitted. The main difference between the liquid crystal display panel 10B of the second embodiment and the liquid crystal display panel 10A of the first embodiment is that the viewing angle control second electrode 30A is different in the liquid crystal display panel 10A of the first embodiment. Is formed so as to cover the second transparent substrate 29, whereas in the liquid crystal display panel 10B of the second embodiment, the second electrode 30B for viewing angle control is the overcoat layer 33 of the sub-pixel 15B for viewing angle control. It is the point formed above.

As shown in FIG. 6, in the display sub-pixel 14B of the second embodiment, the light shielding layer 31 is applied to the lowermost layer of the second transparent substrate 29 of the color filter substrate CF, and light of a different color is used for each display sub-pixel 14B. A transparent color filter layer 32 is formed. The light-shielding layer 31 and the color filter layer 32 of the display sub-pixel 14B and the second transparent substrate 2 of the viewing-angle control sub-pixel 15B
An overcoat layer 33 is laminated so as to cover 9.

In the viewing angle control sub-pixel 15B, the ITO is so covered as to cover the overcoat layer 33.
The second electrode 30B for viewing angle control made of a transparent conductive material such as IZO is formed only on the subpixel 15B for viewing angle control. Then, a resin layer 35 made of a transparent resin material such as a photoresist is formed so as to cover the viewing angle control second electrode 30B. The overcoat layer 33 of the display subpixel 14B and the resin layer 35 of the viewing angle control subpixel 15B.
A second alignment film 34 is formed so as to cover the surface. The second alignment film 34 includes the first alignment film 2.
7 is rubbed in the opposite direction. The resin layer 35 is an additional dielectric film, and its thickness is designed to satisfy C1 / C2 ≧ 0.5. Note that C in the second embodiment
2 is the total of the capacity of the first alignment film 27, the capacity of the resin layer 35, and the capacity of the second alignment film 34.

Thus, when the second electrode for viewing angle control is formed on the overcoat layer, a dielectric film (resin layer of the second embodiment) is formed between the second electrode for viewing angle control and the second alignment film. 35), the TV curve of the viewing angle control sub-pixel is made gentler than before, and the T of the display sub-pixel is reduced.
It can be close to the V curve.

[Third Embodiment]
Next, a liquid crystal display panel 10C according to a third embodiment will be described with reference to FIGS. 7 to 10 in the liquid crystal display panel 10C of the third embodiment correspond to FIGS. 1 to 4 in the liquid crystal display panel 10A of the first embodiment, respectively. In the liquid crystal display panel 10C of the third embodiment, the same reference numerals are given to portions having the same configuration as the liquid crystal display panel 10A of the first embodiment, and the subscripts are given to the reference numerals having subscripts. The detailed description thereof will be omitted.

The main difference between the liquid crystal display panel 10C of the third embodiment and the liquid crystal display panel 10A of the first embodiment is that it operates as a pixel electrode of the display sub-pixel 14A of the first embodiment. In contrast to the upper electrode 24, the lower electrode 20 (see FIGS. 8 and 10) operates as a pixel electrode of the display sub-pixel 14C of the third embodiment. For this, the third
In the liquid crystal display panel 10 </ b> C of the embodiment, the interelectrode insulating film 36 between the lower electrode 20 and the upper electrode 24.
The additional dielectric film of the viewing angle control subpixel 15C can be formed in the same process as the manufacturing process.

As shown in FIG. 7, in the liquid crystal display panel 10C of the third embodiment, both the display sub-pixel 14C and the viewing angle control sub-pixel 15C of the array substrate AR have scanning lines 16 extending in the X-axis direction. , A signal line 18 extending in the Y-axis direction, and a TFT. Display sub-pixel 14C
The TFT of the viewing angle control sub-pixel 15C has the same configuration.

As shown in FIGS. 8 to 10, the array substrate AR uses the first transparent substrate 19 as a base.
Scan lines 16 are formed on the first transparent substrate 19. From the scanning line 16, the gate electrode G
Is extended. A gate insulating film 21 is laminated so as to cover the scanning line 16 and the gate electrode G. Then, the semiconductor layer 2 is formed on the gate insulating film 21 overlapping the gate electrode G in plan view.
2 is formed. A signal line 18 is formed on the gate insulating film 21. A source electrode S extends from the signal line 18, and the source electrode S is in partial contact with the surface of the semiconductor layer 22.

Further, a drain electrode D formed simultaneously with the same material as the signal line 18 and the source electrode S is provided on the gate insulating film 21, and the drain electrode D is disposed in proximity to the source electrode S and the semiconductor layer 22. Partially touching. The gate electrode G, the gate insulating film 21, the semiconductor layer 22, the source electrode S, and the drain electrode D constitute a TFT serving as a switching element. Further, a transparent passivation film 23 made of, for example, silicon nitride or silicon oxide is laminated so as to cover the exposed portions of the signal line 18, the TFT, and the gate insulating film 21. An interlayer resin film 37 made of a transparent resin material such as a photoresist and having a flat surface is formed so as to cover the passivation film 23.

In the display sub-pixel 14C, the lower electrode 20 made of a transparent conductive material such as ITO or IZO is formed so as to cover the interlayer resin film 37. In the viewing angle control sub-pixel 15C, as shown in FIGS. 7, 9, and 10, the viewing angle control first electrode 25 is formed in the same process and with the same material as the lower electrode 20 so as to cover the interlayer resin film 37. Is formed in a substantially totally transparent region of the viewing angle control sub-pixel 15C. In the display sub-pixel 14C, a contact hole 26 that reaches the drain electrode D of the TFT through the interlayer resin film 37 and the passivation film 23 is formed, and the lower electrode 20 is electrically connected to the drain electrode D of the TFT. . Therefore, the lower electrode 2
0 operates as a pixel electrode. Similarly, in the viewing angle control sub-pixel 15C, the interlayer resin film 37 is used.
A contact hole 26 that penetrates the passivation film 23 and reaches the drain electrode D of the TFT is formed, and the viewing angle control first electrode 25 is electrically connected to the drain electrode D of the TFT. Therefore, the viewing angle control first electrode 25 operates as a pixel electrode.

First viewing angle control of the lower electrode 20 of the display subpixel 14C and the viewing angle control subpixel 15C.
A transparent interelectrode insulating film 36 made of, for example, silicon nitride or silicon oxide is laminated so as to cover the electrode 25. In the display subpixel 14C, the upper electrode 24 made of a transparent conductive material such as ITO or IZO so as to cover the interelectrode insulating film 36 is adjacent to the display subpixel 1.
It is formed across 4C. As in the case of the first embodiment, a slit-like opening 28 is formed in the upper electrode 24. The upper electrode 24 is connected to a common wiring (not shown) at the periphery of the display region 12C and operates as a common electrode. A first alignment film 27 is laminated so as to cover the surfaces of the upper electrode 24 and the interelectrode insulating film 36. The first alignment film 27 is rubbed in the Y-axis direction of FIG.

The configuration of the color filter substrate CF of the third embodiment is the same as that of the color filter substrate CF of the first embodiment. Therefore, in the viewing angle control sub-pixel 15C, the first viewing angle control sub-pixel 15C is used.
Overcoat layer 3 as an additional dielectric film between electrode 25 and second electrode 30C for viewing angle control
3 is formed. Further, in the viewing angle control sub-pixel 15C, the first electrode 2 for viewing angle control.
Since the interelectrode insulating film 36 is laminated so as to cover 5, the interelectrode insulating film 36 also becomes an additional dielectric film. That is, C2 in the third embodiment is the total of the capacitance of the first alignment film 27, the capacitance of the overcoat layer 33, the capacitance of the passivation film 23, and the capacitance of the second alignment film 34.

Thus, in the FFS mode liquid crystal display panel 10C of the third embodiment, the lower electrode 20 is a pixel electrode, but in the viewing angle display subpixel 15C, the interelectrode insulating film 36 of the display subpixel 14C is formed. An additional dielectric film can be formed simultaneously with the formation. This reduces the manufacturing process. In addition, in this way, a dielectric film is also added on the array substrate AR side, so that the TV curve of the viewing angle control sub-pixel can be made gentler than before and can be brought closer to the TV curve of the display sub-pixel (FIG. 11). B3).

In the liquid crystal display panels 10A to 10C of the first to third embodiments (including the modified example of the first embodiment), the case where the display sub-pixel operates in the FFS mode has been described. However, as shown in Patent Documents 1 and 2, the IPS mode and VA
The viewing angle control can be performed on the liquid crystal display panel in the mode. In the above embodiment, one viewing angle control subpixel is always formed together with a display subpixel in one pixel. However, one viewing angle control subpixel is always included in one pixel. Since it is not necessary, in the liquid crystal display panel, one pixel has a viewing angle control sub-pixel,
There may be a case in which a pixel having no viewing angle control sub-pixel is mixed.

10A to 10C ... Liquid crystal display panels 11A to 11C ... Pixels 12A to 12C ... Display area 13A to 13C ... Viewing angle control area 14A to 14C ... Display sub-pixels 15A to 15C
... Viewing angle control sub-pixel 16 ... scanning line 17 ... common wiring 18 ... signal line 19 ... first
Transparent substrate 20 ... Lower electrode 21 ... Gate insulating film 22 ... Semiconductor layer 23 ... Passivation film 24 ... Upper electrode 25 ... First electrode for viewing angle control 26 ... Contact hole 27 ...
1st orientation film 28 ... Slit 29 ... 2nd transparent substrate 30A-30C ... 2nd for viewing angle control
Electrode 31 ... Light-shielding layer 32 ... Color filter layer 33 ... Overcoat layer 34 ... Second
Alignment film 35 ... Resin layer 36 ... Interelectrode insulating film 37 ... Interlayer resin film AR ... Array substrate C
F ... Color filter substrate D ... Drain electrode G ... Gate electrode LC ... Liquid crystal layer S ... Source electrode TFT ... Thin film transistor

Claims (9)

A first substrate and a second substrate disposed opposite to each other with a liquid crystal layer interposed therebetween, wherein a display sub-pixel and a viewing angle control sub-pixel are disposed;
The viewing angle control sub-pixel includes a pair of electrodes composed of an electrode formed on the first substrate and an electrode formed on the second substrate, and a pair of orientations sandwiching the liquid crystal layer between the pair of electrodes. A liquid crystal display panel on which a film is formed,
2. The liquid crystal display panel according to claim 1, wherein the viewing angle control sub-pixel is of a vertical electric field type, and a dielectric film different from the liquid crystal layer and the alignment film is formed between the pair of electrodes. In the viewing angle control sub-pixel, a capacitance of the liquid crystal layer between the pair of electrodes is C1,
When the capacitance of the dielectric film other than the liquid crystal layer is C2,
C2 / C1 ≧ 0.5
The liquid crystal display panel according to claim 1, wherein the relationship is satisfied. At least one of a resin film and an inorganic insulating film is formed on the display subpixel, and the dielectric film of the viewing angle control subpixel is the resin film and the inorganic insulating film formed on the display subpixel. The liquid crystal display panel according to claim 1, wherein the liquid crystal display panel is made of the same material as at least one of the above. 2. The display sub-pixel operates in an in-plane switching mode in which a pair of electrodes for applying an electric field to liquid crystal molecules of the liquid crystal layer is formed on the first substrate. LCD display panel. The display sub-pixel operates in a fringe field switching mode in which a pair of electrodes for applying an electric field to liquid crystal molecules of the liquid crystal layer is formed on the first substrate, and the inorganic insulating film is the display sub-pixel. 4. The liquid crystal display panel according to claim 3, wherein the liquid crystal display panel is made of the same material as the interelectrode insulating film formed between the pair of electrodes of the pixel. The liquid crystal display panel according to claim 3, wherein the resin film is formed of the same material as the overcoat layer covering the color filter layer. The liquid crystal display panel according to claim 1, wherein the viewing angle control subpixel has a voltage-transmittance curve similar to that of the display subpixel. 8. The liquid crystal display panel according to claim 7, wherein the viewing angle control sub-pixel commonly uses a gradation table of the display sub-pixel. An electrode formed on the second substrate side of the viewing angle control sub-pixel extends over the display sub-pixel and serves also as a shield electrode of the display sub-pixel. The liquid crystal display panel according to claim 4.

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