WO2011155143A1

WO2011155143A1 - Liquid crystal display device

Info

Publication number: WO2011155143A1
Application number: PCT/JP2011/002949
Authority: WO
Inventors: 柴崎明; 田沼清治
Original assignee: シャープ株式会社
Priority date: 2010-06-07
Filing date: 2011-05-26
Publication date: 2011-12-15

Abstract

In a liquid crystal display device (1) which uses PSA liquid crystals, the liquid crystal capacities (C_R, C_G, C_B) of a liquid crystal layer (4), in regions (E_B, E_G, E_R) wherein a red layer (R), a green layer (G), and a blue layer (B) are each arranged, are made to be substantially constant by setting the widths (W_R, W_G, W_B) of lines of a pixel electrode (19) in the regions (E_B, E_G, E_R) wherein the red layer (R), green layer (G), and blue layer (B) are each arranged, to correspond with the liquid crystal capacity ratio. Also, in the device, the pull-in voltage during pixel charging is uniform.

Description

Liquid crystal display device

The present invention relates to a liquid crystal display device using a switching element such as a thin film transistor.

In recent years, as a display panel for mobile terminal devices such as mobile phones and portable game machines and various electronic devices such as notebook computers, it has the advantages of being thin and lightweight, being able to be driven at a low voltage, and consuming little power. Liquid crystal display devices are widely used.

In general, a liquid crystal display device includes a pair of substrates disposed opposite to each other (that is, a TFT (Thin Film Transistor) substrate and a CF (Color Filter) substrate), a liquid crystal layer provided between the pair of substrates, A pair of substrates are bonded to each other, and a sealing material provided in a frame shape is provided between the substrates to enclose liquid crystal.

The liquid crystal display device is provided in common to a plurality of pixels arranged in a matrix, and includes a pixel electrode included in each pixel and a common electrode arranged so as to face the pixel electrode with a liquid crystal layer interposed therebetween. (Or a counter electrode).

In addition, as a liquid crystal display device, various displays that form an image with pixels are widely used as information and video display means. For example, one pixel includes a red layer R, a green layer G, and a blue layer. It is generally configured by a primary color layer composed of B and performing color display using a color filter having the primary color layer.

Here, in general, in order to improve the chromaticity change based on the viewing angle characteristics, the red layer R, the green layer G are changed by changing the thicknesses of the red layer R, the green layer G, and the blue layer B constituting the color filter. In addition, there has been proposed a liquid crystal display device adopting a structure (multi-gap structure) in which the thickness (cell gap) of the liquid crystal layer corresponding to the blue layer B is made different.

However, in this multi-gap structure, since the thickness of the liquid crystal layer corresponding to each colored layer is different, a difference occurs in the capacity of the liquid crystal layer corresponding to each colored layer. Accordingly, since the pull-in voltage at the time of pixel charging differs depending on each colored layer, the optimum voltage value of the common electrode also differs for each colored layer region. Therefore, in the method of adjusting the voltages of the common electrodes of all the pixels at once, which is normally performed, there is a common electrode that is not set to an optimum voltage value, and as a result, flicker is generated in the display image. There was a problem.

Therefore, a liquid crystal display device having a multi-gap structure has been proposed that has a structure that can reduce image quality deterioration due to flicker. More specifically, when the thicknesses of the liquid crystal layers corresponding to the red layer R, the green layer G, and the blue layer B are d _R , d _G , and d _B , respectively, a relationship of d _R > d _G > d _B When the areas of the pixel electrodes corresponding to the red layer R, the green layer G, and the blue layer B are S _R , S _G , and S _B , respectively, the relationship of S _R > S _G > S _B is established. An established liquid crystal display device is disclosed. According to such a liquid crystal display device, the capacitance of the liquid crystal layer is proportional to S (area of the pixel electrode) / d (thickness of the liquid crystal layer), and each of the red layer R, the green layer G, and the blue layer B Since the S / d values are substantially the same in the arranged region, the capacitance of the liquid crystal layer corresponding to each of the red layer R, the green layer G, and the blue layer B can be made substantially constant. As a result, it is described that image quality deterioration due to flicker can be reduced (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 2003-5204

Here, in recent years, there is a request for further improving the contrast ratio and response speed in the liquid crystal display device, and further, there is a request for realizing an improvement in transmittance. Therefore, a liquid crystal display device using a PSA (Polymer-SustainedｉｎAlignment) liquid crystal has been proposed. In this PSA type liquid crystal display device, a slit for regulating the alignment of liquid crystal molecules is formed in the pixel electrode (or the counter electrode), and the liquid crystal molecules are aligned, thereby improving the contrast ratio and increasing the contrast ratio. And a high response speed.

However, in the liquid crystal display device using the PSA liquid crystal, since a slit is formed in the electrode, the liquid crystal capacitance is not proportional to the area of the electrode. Therefore, in the method of the liquid crystal display device described in Patent Document 1, The liquid crystal capacity of the liquid crystal layer corresponding to each of the red layer R, the green layer G, and the blue layer B cannot be made substantially constant. As a result, there is a problem that it is difficult to reduce image quality deterioration due to flicker.

Accordingly, the present invention has been made in view of the above-described problems, and in a liquid crystal display device using PSA liquid crystal, a liquid crystal display capable of making the same pull-in voltage during pixel charging and preventing occurrence of flicker. An object is to provide an apparatus.

In order to achieve the above object, a liquid crystal display device according to the present invention includes a first substrate having a first electrode and a plurality of coloring layers disposed opposite to the first substrate and including a red layer, a green layer, and a blue layer. A liquid crystal formed by a PSA liquid crystal provided between a first substrate and a second substrate, a second substrate having a color filter in which pixels having layers are arranged, and a second electrode provided on the color filter. and a layer, the red layer, green layer, and each _T R the thickness of the liquid crystal layer in each of which is arranged a region of the blue _layer, T G, when the _{T _B,} the relationship of _T _R> T _G> T _B In the first electrode or the second electrode, a slit for controlling the alignment of liquid crystal molecules and a line partitioned by the slit are formed, and a voltage is applied between the first electrode and the second electrode. Liquid crystal display device that drives liquid crystal molecules In the red layer, green layer, and blue layer, the liquid crystal capacity of the liquid crystal layer in the region where the reference colored layer is disposed is C _k , and the liquid crystal capacity of the liquid crystal layer in the region _where the red layer is disposed C _R , C _{G is} the liquid crystal capacity of the liquid crystal layer in the region where the green layer is disposed, C _{B is} the liquid crystal capacity of the liquid crystal layer in the region where the blue layer is disposed, and W is the line width in the region where the red layer is disposed. _{R ([mu]} m), the width of the line in the region where the green layer is disposed W _{G (μm),} width W _{B (μm)} of the lines in the region where the blue layer is arranged, if the width of the slit was 3μm In addition,
Width _{W R} of the line is, satisfies the equation (1) below,
[Equation 1]
W _R = (3 × C _R / C _k −2.37) / (1.23-C _R / C _k ) (1)
Width _{W G} of the line is, satisfies the equation (2) below,
[Equation 2]
W _G = (3 × C _G / C _k −2.37) / (1.23-C _G / C _k ) (2)
The liquid crystal display device width W _B of the line, and satisfies the equation (3) below.
[Equation 3]
W _B = (3 × C _B / C _k -2.37) / (1.23-C _B / C _k ) (3)

According to this configuration, in the liquid crystal display device using the PSA liquid crystal, the thicknesses T _R , T _G , and T _B of the liquid crystal layers in the regions where the red layer, the green layer, and the blue layer are arranged are different (that is, T even _R> _{_T} G> _T _B) case, it is possible to cancel out the thickness of the liquid crystal layer _T _R, T G, a liquid crystal capacitance _C R due to the difference of _{T _B,} C G, the difference in _{C B,} red the width of the line in the layers are arranged regions W _R, width of the line in the region where the green layer is disposed W _G, and a blue layer is the width of a line in the arrangement area by setting W _B, slit and the line It is possible to adjust the electrode area of the first electrode or the second electrode on which is formed. Therefore, the red layer, green layer, and since the liquid crystal capacitance C _R of the liquid crystal layer in the region that are each located in the blue _layer, C _G, a C _B can be made substantially constant, a liquid crystal display device using a PSA liquid crystal In FIG. 5, the pull-in voltage at the time of pixel charging can be made the same, and the occurrence of flicker can be prevented.

In the liquid crystal display device of the present invention, a first substrate having a first electrode and pixels having a plurality of colored layers made of a red layer, a green layer, and a blue layer are arranged to face the first substrate. And a second substrate having a color filter and a second electrode provided on the color filter, and a liquid crystal layer provided between the first substrate and the second substrate and formed of PSA liquid crystal. layer, a green layer, each thickness _T R of the liquid crystal layer in the region that are each located in the blue _layer, T G, when the _{T _B,} has a relation of _{_{T R = T G> T B}} , the first electrode Alternatively, the second electrode is formed with slits for controlling the alignment of liquid crystal molecules and lines partitioned by the slits, and the liquid crystal that drives the liquid crystal molecules by applying a voltage between the first electrode and the second electrode. A display device comprising a red layer, a green layer, Of the liquid crystal layer in the region where the reference colored layer is disposed, C _k , the capacity of the liquid crystal layer in the region _where the red layer is disposed, C _R , and the liquid crystal in the region where the green layer is disposed The capacitance of the layer is C _G , the capacitance of the liquid crystal layer in the region where the blue layer is arranged is C _B , the line width in the region where the red layer is arranged is W _R (μm), and the line in the region where the green layer is arranged Is W _G (μm), the line width in the region where the blue layer is arranged is W _B (μm), and the slit width is 3 μm,
Width _{W R} of the line is, satisfies the equation (1) below,
[Equation 1]
W _R = (3 × C _R / C _k −2.37) / (1.23-C _R / C _k ) (1)
Width _{W G} of the line is, satisfies the equation (2) below,
[Equation 2]
W _G = (3 × C _G / C _k −2.37) / (1.23-C _G / C _k ) (2)
The liquid crystal display device width W _B of the line, and satisfies the equation (3) below.
[Equation 3]
W _B = (3 × C _B / C _k -2.37) / (1.23-C _B / C _k ) (3)

According to this configuration, in the liquid crystal display device using the PSA liquid crystal, the thicknesses T _R , T _G , and T _B of the liquid crystal layers in the regions where the red layer, the green layer, and the blue layer are arranged are different (that is, T even _R = _{_T} G> _T _B) case, it is possible to cancel out the thickness of the liquid crystal layer _T _R, T G, a liquid crystal capacitance _C R due to the difference of _{T _B,} C G, the difference in _{C B,} red the width of the line in the layers are arranged regions W _R, width of the line in the region where the green layer is disposed W _G, and a blue layer is the width of a line in the arrangement area by setting W _B, slit and the line It is possible to adjust the electrode area of the first electrode or the second electrode on which is formed. Therefore, the red layer, green layer, and since the liquid crystal capacitance C _R of the liquid crystal layer in the region that are each located in the blue _layer, C _G, a C _B can be made substantially constant, a liquid crystal display device using a PSA liquid crystal In FIG. 5, the pull-in voltage at the time of pixel charging can be made the same, and the occurrence of flicker can be prevented.

In the liquid crystal display device of the present invention, the first electrode may be formed with a slit and a line.

Further, in the liquid crystal display device of the present invention, a configuration may be adopted in which slits and lines are formed in the second electrode.

In the liquid crystal display device of the present invention, the first electrode and the second electrode may be formed of indium tin oxide or indium zinc oxide.

According to this configuration, the first electrode and the second electrode can be formed from an inexpensive and versatile material.

According to the present invention, in the liquid crystal display device using the PSA liquid crystal, the pull-in voltage at the time of pixel charging can be made the same, and the occurrence of flicker can be prevented.

It is a top view which shows the whole structure of the liquid crystal display device which concerns on embodiment of this invention. It is sectional drawing of the liquid crystal display device which concerns on embodiment of this invention. 1 is an equivalent circuit diagram of a liquid crystal display device according to an embodiment of the present invention. It is sectional drawing which shows the whole structure of the TFT substrate which comprises the liquid crystal display device which concerns on embodiment of this invention. It is sectional drawing which shows the whole structure of the display part of the liquid crystal display device which concerns on embodiment of this invention. It is a top view for demonstrating the part corresponding to a red layer of the pixel electrode in the liquid crystal display device which concerns on embodiment of this invention. It is a top view for demonstrating the part corresponding to the green layer of the pixel electrode in the liquid crystal display device which concerns on embodiment of this invention. It is a top view for demonstrating the part corresponding to a blue layer of the pixel electrode in the liquid crystal display device which concerns on embodiment of this invention. It is a graph which shows the relationship between the thickness ratio of a liquid crystal layer at the time of using the pixel electrode in which the slit was formed, and a liquid crystal capacitance ratio. It is a graph which shows the relationship between the electrode area ratio of a pixel electrode at the time of using the pixel electrode in which the slit was formed, and a liquid crystal capacitance ratio. It is sectional drawing for demonstrating the structure used in order to calculate the relationship shown in FIG. 9, FIG. It is sectional drawing which shows the modification of the display part of the liquid crystal display device which concerns on embodiment of this invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the following embodiment.

FIG. 1 is a plan view showing an overall configuration of a liquid crystal display device according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view of the liquid crystal display device according to an embodiment of the present invention. 3 is an equivalent circuit diagram of the liquid crystal display device according to the embodiment of the present invention, and FIG. 4 is a cross-sectional view showing the entire configuration of the TFT substrate constituting the liquid crystal display device according to the embodiment of the present invention. is there. FIG. 5 is a cross-sectional view showing the overall configuration of the display unit of the liquid crystal display device according to the embodiment of the present invention.

As shown in FIGS. 1 and 2, the liquid crystal display device 1 includes a TFT substrate 2 that is a first substrate, a CF substrate 3 that is a second substrate disposed opposite to the TFT substrate 2, a TFT substrate 2, The liquid crystal layer 4 which is a display medium layer sandwiched between the CF substrates 3 and the TFT substrate 2 and the CF substrate 3 are sandwiched, and the TFT substrate 2 and the CF substrate 3 are bonded to each other and the liquid crystal In order to enclose the layer 4, a sealing material 40 provided in a frame shape is provided.

The sealing material 40 is formed so as to go around the liquid crystal layer 4, and the TFT substrate 2 and the CF substrate 3 are bonded to each other via the sealing material 40. In addition, the liquid crystal display device 1 includes a plurality of photo spacers (not shown) for regulating the thickness of the liquid crystal layer 4 (that is, the cell gap).

As shown in FIG. 1, the liquid crystal display device 1 is formed in a rectangular shape, and in the longitudinal direction X of the liquid crystal display device 1, the TFT substrate 2 protrudes from the CF substrate 3 on its upper side, and the protrusion In the region, a plurality of display wirings such as gate lines and source lines, which will be described later, are drawn out to form a terminal region T.

Further, in the liquid crystal display device 1, a display area D for displaying an image is defined in an area where the TFT substrate 2 and the CF substrate 3 overlap. Here, the display area D is configured by arranging a plurality of pixels E (see FIG. 5), which is the minimum unit of an image, in a matrix.

Further, as shown in FIG. 1, the sealing material 40 is provided in a rectangular frame shape surrounding the entire periphery of the display area D. The frame width of the sealing material 40 is not particularly limited, but can be set to 0.5 mm or more and 2.0 mm or less, for example.

As shown in FIGS. 3 and 4, the TFT substrate 2 covers an insulating substrate 6 such as a glass substrate, a plurality of gate lines 11 extending in parallel with each other on the insulating substrate 6, and the gate lines 11. And a plurality of source lines 14 extending in parallel to each other in a direction orthogonal to the gate lines 11 on the gate insulating film 12. The TFT substrate 2 includes a plurality of TFTs 5 provided at each intersection of the gate lines 11 and the source lines 14, and a first interlayer insulating film provided in order so as to cover the source lines 14 and the TFTs 5. 15 and the second interlayer insulating film 16, a plurality of pixel electrodes 19 provided in a matrix on the second interlayer insulating film 16 and connected to each of the TFTs 5, and the pixel electrodes 19. And an alignment film 9 provided so as to cover it.

As shown in FIG. 4, the TFT 5 includes a gate electrode 17 in which each gate line 11 protrudes to the side, a gate insulating film 12 provided so as to cover the gate electrode 17, and a gate on the gate insulating film 12. A semiconductor layer 13 provided in an island shape at a position overlapping with the electrode 17, and a source electrode 18 and a drain electrode 20 provided so as to face each other on the semiconductor layer 13 are provided.

Here, the source electrode 18 is a portion where each source line 14 protrudes to the side. Further, as shown in FIG. 4, the drain electrode 20 is connected to the pixel electrode 19 through a contact hole 30 formed in the first interlayer insulating film 15 and the second interlayer insulating film 16. Further, as shown in FIG. 4, the semiconductor layer 13 includes a lower intrinsic amorphous silicon layer 13 a and an upper n ⁺ amorphous silicon layer 13 b doped with phosphorus, and is exposed from the source electrode 18 and the drain electrode 20. The intrinsic amorphous silicon layer 13a that constitutes the channel region.

Further, the liquid crystal display device 1 of the present embodiment is a transmissive device, and in the display region D of the liquid crystal display device 1, a transmissive region T is defined as shown in FIG. As the liquid crystal display device 1, a transflective device in which a reflective region and a transmissive region are defined in the display region D may be used.

The pixel electrode 19 is formed of a transparent conductor such as ITO (indium tin oxide) or IZO (indium zinc oxide).

The material constituting the first interlayer insulating film 15 is not particularly limited, and examples thereof include silicon oxide (SiO ₂ ), silicon nitride (SiNx (x is a positive number)), and the like. The thickness of the first interlayer insulating film 15 is preferably 600 nm or more and 1000 nm or less. This is because when the thickness of the first interlayer insulating film 15 is less than 600 nm, it may be difficult to planarize the first interlayer insulating film 15, and when the thickness is larger than 1000 nm, This is because the etching may cause a disadvantage that it is difficult to form the contact hole 30.

As shown in FIG. 5, the CF substrate 3 includes an insulating substrate 21 such as a glass substrate, a color filter 22 provided on the insulating substrate 21, and a common electrode 24 provided so as to cover the color filter 22. A photo spacer (not shown) provided in a column shape on the common electrode 24 and an alignment film 26 provided so as to cover the common electrode 24 and the photo spacer.

The common electrode 24 is formed of a transparent conductor such as ITO (indium tin oxide) or IZO (indium zinc oxide) in the same manner as the pixel electrode 19 described above.

As shown in FIG. 5, the color filter 22 includes a plurality of types of colored layers 28 (that is, a red layer 22R, a green layer 22G, and a blue layer 22B) provided for each pixel E, and a light shielding film. And a black matrix 27. The black matrix 27 is provided between the adjacent colored layers 28 and has a role of partitioning the plurality of types of colored layers 28.

The black matrix 27 is made of a metal material such as Ta (tantalum), Cr (chromium), Mo (molybdenum), Ni (nickel), Ti (titanium), Cu (copper), Al (aluminum), or a black pigment such as carbon. Are dispersed or a resin material in which a plurality of colored layers having light transmittance are laminated. The photo spacer is made of, for example, an acrylic photosensitive resin, and is formed by a photolithography method.

The color filter 22 has a display region D in which a plurality of pixels E each having a plurality of colored layers 28 composed of a red layer R, a green layer G, and a blue layer B are two-dimensionally arranged.

Further, in the present embodiment, as shown in FIG. 5, the thickness of the liquid crystal layer 4 in the region where each of the red layer R, the green layer G, and the blue layer B is disposed (that is, the region where the red layer R is disposed). E _R, the green layer G is disposed region _{E G,} and the blue layer B are each respectively _T the thickness) of the liquid crystal layer 4 in the R of the arrangement region _{E _B,} T G, when the _{T B,} _{T R} > T _G > T _B is established.

Further, the liquid crystal layer 4 is formed of PSA (Polymer-Sustained Alignment) liquid crystal from the viewpoint of improving the contrast ratio and the response speed and improving the transmittance.

Here, the PSA liquid crystal is formed of a liquid crystal material in which a small amount of a photopolymerizable polymer (for example, biphenyl acrylate) is added to the liquid crystal, and liquid crystal molecules are formed using electrodes (pixel electrodes or common electrodes) in which slits are formed. It refers to the liquid crystal to be aligned.

From the same viewpoint, an electrode provided with a slit is used as the pixel electrode 19. More specifically, as shown in FIGS. 5 and 6, the pixel electrode 19, the portion corresponding to the red layer R (i.e., the pixel electrode 19, the portion of the area E _R to the red layer R is disposed) 19R Are formed with a plurality of slits K _R (portions where no electrode material is present) for controlling the alignment of liquid crystal molecules when a voltage is applied.

The slit _{K R} has a predetermined width _{H R,} of the pixel electrode 19, the portion 19R of the region _{E R} of the red layer R is arranged, adjacent to the slit _{K R,} the slit _{K R} A plurality of partitioned lines (portions where electrode material is present) _LR are formed. The line _{L R} has a predetermined width _{W R.}

Similarly, as shown in FIGS. 5 and 7, the pixel electrode 19, the portion corresponding to the green layer G (i.e., the pixel electrode 19, part of the region E _G the green layer G is placed) to 19G a plurality of slits K _{G (portion} where the electrode material is not present) that controls the orientation of liquid crystal molecules when a voltage is applied is formed.

The slit _{K G} has a predetermined width _{H G,} the pixel electrode 19, the portion 19G of the green layer G is disposed region _{E G} is adjacent to the slit _{K G,} the slit _{K G} compartmentalized multiple lines (partial electrode material are present) L _G is formed. The line _{L G} has a predetermined width _{W G.}

Similarly, as shown in FIGS. 5 and 8, the pixel electrode 19 corresponds to the portion corresponding to the blue layer B (that is, the portion of the pixel electrode 19 in the region EB where the blue layer B is disposed) 19 </ _b > _B. a plurality of slits K _{B (portion} where the electrode material is not present) that controls the orientation of liquid crystal molecules when a voltage is applied is formed.

The slit _{K B} has a predetermined width _{H B,} the pixel electrode 19, the portion 19B of the blue layer B is disposed region _{E B} is adjacent to the slit _{K B,} the slit _{K B} a plurality of lines which are compartments (electrode material present portion) L _B is formed. The line _{L B} has a predetermined width _{W B.}

The liquid crystal display device 1 having the above-described configuration is configured to transmit light from a backlight (not shown) incident from the TFT substrate 2 side in the transmission region T.

In the liquid crystal display device 1, one pixel E is formed for each pixel electrode 19. When a gate signal is sent from the gate line 11 and the TFT 5 is turned on in each pixel E, the source line A source signal is sent from 14, and a predetermined charge is written into the pixel electrode 19 via the source electrode 18 and the drain electrode 20. A potential difference is generated between the pixel electrode 19 and the common electrode 24, and a predetermined voltage is applied to the liquid crystal layer 4. That is, by applying a voltage between the pixel electrode 19 and the common electrode 24, the liquid crystal molecules of the liquid crystal layer 4 are driven. In the liquid crystal display device 1, according to the magnitude of the applied voltage, the liquid crystal molecules An image is displayed by adjusting the transmittance of light incident from the backlight by utilizing the change in the orientation state.

Here, in the present embodiment, first, the thicknesses T _R , T _G , T of the liquid crystal layer 4 in the regions E _R , E _G , E _{B where} the red layer R, the green layer G, and the blue layer B are respectively arranged. _{From B} , the capacity ratio of the liquid crystal layer 4 is determined. Next, based on the capacitance ratio of the liquid crystal layer 4, pixel electrodes for making the capacitance of the liquid crystal layer 4 the same in the regions E _R , E _G , and E _{B where} the red layer R, the green layer G, and the blue layer B are disposed. 19 linewidth (i.e., above the line _L _R, L G, the width of each of the _{_{_{L B W R, W G,}}} W B) is characterized in that to determine.

Hereinafter, this feature will be described in detail. FIG. 9 is a graph showing the relationship between the thickness ratio of the liquid crystal layer and the liquid crystal capacitance ratio when a pixel electrode having a slit is used, and FIG. 10 is a graph when the pixel electrode having a slit is used. It is a graph which shows the relationship between the electrode area ratio of a pixel electrode (namely, ratio of the conductor area with respect to the area of the whole electrode in a pixel electrode), and a liquid crystal capacitance ratio.

The relationship shown in FIG. 9 uses the structure 31 composed of the pixel electrode 19a, the common electrode 24a, and the liquid crystal layer 4a shown in FIG. 11, and changes the thickness T of the liquid crystal layer 4a to change the liquid crystal capacitance C. Was calculated by measuring.

Further, the relationship shown in FIG. 10 uses the structure 31 shown in FIG. 11 and changes the width W of the line L of the pixel electrode 19a to change the electrode area of the liquid crystal capacitor C and the pixel electrode 19a (that is, in the pixel electrode). The conductor area was calculated by measuring S.

The pixel electrode 19a and the common electrode 24a were made of ITO. The liquid crystal layer 4a is made of PSA liquid crystal. Further, the measurement was performed with the width H of the slit K of the pixel electrode 19a being constant (3 μm).

Table 1 shows the thickness T and the liquid crystal capacity C of the obtained liquid crystal layer 4a, the liquid crystal capacity ratio calculated from the thickness T and the liquid crystal capacity C of these liquid crystal layers 4a, and the thickness ratio of the liquid crystal layer 4a. The liquid crystal capacity ratio was calculated based on the liquid crystal capacity when the thickness T was 3.2 μm. The thickness ratio of the liquid crystal layer 4a was calculated based on the case where the thickness T was 3.2 μm.

FIG. 9 is a graph showing the reciprocal of the liquid crystal capacitance ratio shown in Table 1 and the thickness ratio of the liquid crystal layer 4a. From FIG. 9, it can be seen that there is a proportional relationship between the liquid crystal capacitance ratio and the reciprocal of the thickness ratio of the liquid crystal layer 4a.
Liquid crystal capacity ratio = 0.83 × (1 / liquid crystal layer thickness ratio) +0.17 (1)
It will be represented by

Table 2 shows the electrode area S and the liquid crystal capacitance C of the obtained pixel electrode 19a, and the liquid crystal capacitance ratio calculated from the electrode area S and the liquid crystal capacitance C of the pixel electrode 19a and the electrode area ratio of the pixel electrode. The liquid crystal capacity ratio was calculated based on the liquid crystal capacity when the width W of the line L was 3 μm. The electrode area ratio was calculated based on the electrode area when the width W of the line L was 3 μm.

FIG. 10 is a graph showing the liquid crystal capacitance ratio and the electrode area ratio shown in Table 2. From FIG. 10, it can be seen that there is a proportional relationship between the liquid crystal capacitance ratio and the electrode area ratio.
Liquid crystal capacitance ratio = 0.22 × electrode area ratio + 0.79 (2)
It will be represented by

Next, using the above formula (1), in the liquid crystal display device 1 shown in FIG. 5, the liquid crystals in the regions E _R , E _G , E _B in which the red layer R, the green layer G, and the blue layer B are arranged. The liquid crystal capacitance ratio of the liquid crystal layer 4 is determined from the thicknesses T _R , T _G , and T _B of the layer 4.

For example, each slit _K R described _above, K G, the width _H R of _{K _B,} H G, is fixed to _{H B} to 3 [mu] m, to secure the width _{W G} of the line _{L G} in 3 [mu] m. When the thicknesses T _R , T _G , and T _{B of} the liquid crystal layer 4 are T _R = 3.5 μm, T _G = 3.2 μm, and T _B = 2.9 μm, the region E _G in which the green layer G is disposed If based on the thickness _{T G} of the liquid crystal layer 4 in, to the thickness _{T G,} thickness ratio of the thickness _{T R} of the liquid crystal layer 4 in the region _{E R} of the red layer R is _disposed, T _R / T G = 3.5 /3.2≒1.09 becomes also, to the thickness _{T G,} thickness ratio of the thickness _{T B} of the liquid crystal layer 4 in the blue layer B is disposed region _{E B} _{_{is, T B / T G = 2.9}} / 3.2≈0.91.

Since the thickness _TG is the reference, the thickness ratio of the thickness _TG to the thickness _TG is _TG / _TG = 3.2 / 3.2 = 1.

Therefore, when the reference liquid crystal capacitance C _G of the liquid crystal layer 4 in the region E _G the green layer G is placed, the liquid crystal capacitance to C _G, a liquid crystal capacitance C of the liquid crystal layer 4 in the red layer R is disposed region E _R the ratio of _R is next _C R / _{C G,} the above equation _(1), the _{C R / C G = 0.83 ×} (1 / 1.09) + 0.17 ≒ 0.93.

Similarly, when the reference liquid crystal capacitance C _G of the liquid crystal layer 4 in the green layer G is disposed region E _G, with respect to the liquid crystal capacitance C _G, of the liquid crystal layer 4 in the region E _B where the blue layer B disposed The ratio of the liquid crystal capacitance C _B is C _B / _CG , and from the above formula (1), C _B / C _G = 0.83 × (1 / 0.91) + 0.17≈1.08.

Here, as described above, in the structure 31 shown in FIG. 11, since the width H of the slit K of the pixel electrode 19a is constant (3 μm), one pitch per unit length (1 μm) (the width of the line L). The area of W + width H of the slit K) is (width W of the line L + width H of the slit K) × unit length = W + 3 [μm ² ], and the electrode area of the pixel electrode 19a (that is, the area of the line L) is , W / (W + 3) [μm ² ].

In Table 2, since the electrode area ratio of the pixel electrode 19a is calculated based on the area when the width W of the line L is 3 μm (that is, 0.50), the electrode area ratio of the pixel electrode 19a is calculated. Is
Electrode area ratio = electrode area of the pixel electrode 19a / 0.50 = 2W / (W + 3) (3)
It becomes.

Then, substituting equation (3) into equation (2),
W [μm] = (3 × liquid crystal capacitance ratio−2.37) / (1.23-liquid crystal capacitance ratio) (4)
It becomes.

Accordingly, from the formula (4), the width _{W R} of the line _{L R} in the area _{E R} to the red layer R is disposed, the width _{W B} of the line _{L B} in the region _{E B} where the blue layer B disposed, respectively ,
W _R [μm] _{_{= (3 × C R / C}} G -2.37) / (1.23-C R / C G) (5)
W _B [μm] = (3 × C _B / C _G −2.37) / (1.23-C _B / C _G ) (6)
It will be represented by

Then, the above equation _(5), by substituting the _C R / C _G ≒ 0.93, it is possible to obtain a width _{W R} ≒ 1.4 [mu] m of line _{L R.} Similarly, in equation _(6), by substituting _C B / C _G ≒ 1.08, it is possible to obtain a width _{W B} ≒ 5.8 [mu] m of line _{L B.}

That is, each slit _K _R, K G, the width _H R of _{K _B,} H G, is fixed to _{H B} to 3 [mu] m, for a fixed width _{W G} of the line _{L G} in 3 [mu] m, the line _L the width of _R _{W R} and sets to 1.4μm and by setting the width _{W B} of the line _{L B} in 5.8 [mu] m, in the liquid crystal display device 1 using a PSA liquid crystal, the thickness _T R of the liquid crystal layer _4, T G, _{T B} difference is different _{_{_{(i.e., T R> T G> T}}} B) even when the thickness _T R of the liquid crystal layer _4, T G, a liquid crystal capacitor due to the difference in _{_{_{T B C R, C G,}}} C B It is possible to adjust the electrode area of the pixel electrode 19 so as to cancel out.

To a result, the red layer R, a green layer G, and a blue layer region _E B each being disposed of _B, E G, a liquid crystal capacitance _C R of the liquid crystal layer 4 in the _{E _R,} and C G, substantially constant _{C B} Therefore, in the liquid crystal display device using the PSA liquid crystal, the pull-in voltage at the time of pixel charging can be made the same, and the occurrence of flicker can be prevented.

Incidentally, as described above, but the width _{W G} of the line _{L G} is 3 [mu] m, from the formula (4), the width _{W G} of the line _{L G} in the region _{E G} the green layer G is arranged,
W _G [μm] _{_{= (3 × C G / C}} G -2.37) / (1.23-C G / C G) (7)
Next, the above expression _(7), by substituting _C G _/ C G = 1, it is possible to obtain a width _{W G} ≒ 3 [mu] m of line _{L G.}

Thus, in the present invention, among the red layer R, the green layer G, and the blue layer B, the liquid crystal layer 4 in the region where the reference colored layer (in this embodiment, the green layer G) is disposed. (in this embodiment, _{C G)} _{C k} capacity when the, according to the above equation (5) to (7), the line width can be prevented flicker _W _R, W G, be determined _{W B} it can.

Note that the above embodiment may be modified as follows.

In the above embodiment, the liquid crystal display device adopting a structure (multi-gap structure) in which the thickness of the liquid crystal layer 4 corresponding to each colored layer 28 of the red layer R, the green layer G, and the blue layer B is different as the liquid crystal display device. 1, the present invention has been described with reference to a specific color layer (in FIG. 12) among the thicknesses T _R , T _G , and T _B of the liquid crystal layer 4, as shown in FIG. can be applied to a liquid crystal display device 32 employing the structure (semi-multi-gap structure) in which only the different thickness T _B of the liquid crystal layer 4 corresponding to the blue layer B). In this case, as shown in FIG. 12, the liquid crystal layer 4 is configured such that a relationship of T _R = T _G > T _B is established between the thicknesses T _R , T _G , and T _B.

In the embodiment described above, based on the green layer G, line width W _R, W _G, it is configured to determine a W _B, based on the other coloring layers (the red layer R, the blue layer B), the line width _W _R, _W _G, may be configured to determine the _{W B.}

In the above embodiment, the slit _K R to the pixel electrode _19, K G, _{K B} and the line _L _L, L G, it is configured to provide a _{L B,} it is provided with a slit and a line to the common electrode 24 Good.

As an application example of the present invention, there is a liquid crystal display device using a switching element such as a thin film transistor.

1 Liquid crystal display device 2 TFT substrate (first substrate)
3 CF substrate (second substrate)
4 Liquid crystal layer 5 TFT (switching element)
19 Pixel electrode (first electrode)
22 Color filter 24 Common electrode (second electrode)
28 Colored layer 32 Liquid crystal display device B Blue layer E Pixel G Green layer K _R slit K _G slit K _B slit L _R line L _G line L _B line R Red layer

Claims

A first substrate having a first electrode;
A color filter arranged opposite to the first substrate and having a plurality of colored layers composed of a red layer, a green layer, and a blue layer, and a second electrode provided on the color filter. A second substrate having;
A liquid crystal layer provided between the first substrate and the second substrate and formed of PSA liquid crystal;
The red layer, the green layer, and the respective thickness T R of the liquid crystal layer in each of which is arranged a region of the blue layer, T G, when the T B, the relationship T R> T G> T B Have
In the first electrode or the second electrode, a slit for controlling the alignment of liquid crystal molecules and a line partitioned by the slit are formed, and a voltage is applied between the first electrode and the second electrode. A liquid crystal display device for driving the liquid crystal molecules,
Among the red layer, the green layer, and the blue layer, the liquid crystal capacity of the liquid crystal layer in a region where the colored layer serving as a reference is arranged is C k , and the liquid crystal layer in the region where the red layer is arranged The liquid crystal capacitance is C R , the liquid crystal capacitance of the liquid crystal layer in the region where the green layer is arranged is C G , the liquid crystal capacitance of the liquid crystal layer in the region where the blue layer is arranged is C B , and the red layer is arranged The width of the line in the region where the green layer is disposed is W R (μm), the width of the line in the region where the green layer is disposed is W G (μm), and the width of the line in the region where the blue layer is disposed is W B. (Μm), when the width of the slit is 3 μm,
Width W R of the line satisfies a formula (1) below,
[Equation 1]
W R = (3 × C R / C k −2.37) / (1.23-C R / C k ) (1)
Width W G of the line satisfies a formula (2) below,
[Equation 2]
W G = (3 × C G / C k −2.37) / (1.23-C G / C k ) (2)
The liquid crystal display device width W B of the line, and satisfies the equation (3) below.
[Equation 3]
W B = (3 × C B / C k -2.37) / (1.23-C B / C k ) (3)
A first substrate having a first electrode;
A color filter arranged opposite to the first substrate and having a plurality of colored layers composed of a red layer, a green layer, and a blue layer, and a second electrode provided on the color filter. A second substrate having;
A liquid crystal layer provided between the first substrate and the second substrate and formed of PSA liquid crystal;
When the thickness of the liquid crystal layer in the region where each of the red layer, the green layer, and the blue layer is arranged is T R , T G , and T B , there is a relationship of T R = T G > T B. And
In the first electrode or the second electrode, a slit for controlling the alignment of liquid crystal molecules and a line partitioned by the slit are formed, and a voltage is applied between the first electrode and the second electrode. A liquid crystal display device for driving the liquid crystal molecules,
Among the red layer, the green layer, and the blue layer, the capacitance of the liquid crystal layer in the region where the reference colored layer is disposed is C k , and the capacitance of the liquid crystal layer in the region where the red layer is disposed. C R , the capacitance of the liquid crystal layer in the region where the green layer is arranged, C G , the capacitance of the liquid crystal layer in the region where the blue layer is arranged, C B , and the capacitance in the region where the red layer is arranged The width of the line is W R (μm), the width of the line in the region where the green layer is arranged is W G (μm), the width of the line in the region where the blue layer is arranged is W B (μm), When the slit width is 3 μm,
Width W R of the line satisfies a formula (1) below,
[Equation 1]
W R = (3 × C R / C k −2.37) / (1.23-C R / C k ) (1)
Width W G of the line satisfies a formula (2) below,
[Equation 2]
W G = (3 × C G / C k −2.37) / (1.23-C G / C k ) (2)
The liquid crystal display device width W B of the line, and satisfies the equation (3) below.
[Equation 3]
W B = (3 × C B / C k -2.37) / (1.23-C B / C k ) (3)
The liquid crystal display device according to claim 1, wherein the slit and the line are formed in the first electrode.
3. The liquid crystal display device according to claim 1, wherein the slit and the line are formed in the second electrode.
The liquid crystal display device according to any one of claims 1 to 4, wherein the first electrode and the second electrode are formed of indium tin oxide or indium zinc oxide.