WO2012093630A1

WO2012093630A1 - Liquid crystal display device

Info

Publication number: WO2012093630A1
Application number: PCT/JP2011/080368
Authority: WO
Inventors: 壮寿吉田; 下敷領　文一
Original assignee: シャープ株式会社
Priority date: 2011-01-07
Filing date: 2011-12-28
Publication date: 2012-07-12

Abstract

A liquid crystal display device (100) according to the present invention is provided with a plurality of color display pixels including color display pixels (D₁, D₂). Each of the plurality of color display pixels has a plurality of pixels including pixels (R, G, B) and each of the plurality of pixels has sub pixels (a, b). When each of a pixel (R₁) of the color display pixel (D₁) and a pixel (R₂) of the color display pixel (D₂) displays at least in a certain middle gradation, the voltage difference ΔV₁ between the effective voltage of the sub pixel (R_1a) and the effective voltage of the sub pixel (R_1b) in the pixel (R₁) of the color display pixel (D₁) is different from the voltage difference ΔV₂ between the effective voltage of the sub pixel (R_2a) and the effective voltage of the sub pixel (R_2b) in the pixel (R₂) of the color display pixel (D₂).

Description

Liquid crystal display

The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device having a multi-pixel structure.

The liquid crystal display device is a flat display device having excellent features such as high definition, thinness, light weight and low power consumption. In recent years, the display performance has been improved, the production capacity has been improved, and the price competitiveness with respect to other display devices has been improved. As a result, the market scale is expanding rapidly. In a conventional twisted nematic mode (TN mode) liquid crystal display device, the major axis of liquid crystal molecules having positive dielectric anisotropy is substantially parallel to the substrate surface, and the liquid crystal layer The alignment treatment is performed so that the substrate is twisted approximately 90 degrees between the upper and lower substrates along the thickness direction. When a voltage is applied to the liquid crystal layer, the liquid crystal molecules rise in parallel with the electric field, and the twist alignment (twist alignment) is eliminated. In a TN mode liquid crystal display device, the amount of transmitted light is controlled by utilizing a change in optical rotation accompanying a change in the orientation of liquid crystal molecules due to a voltage.

Such a TN mode liquid crystal display device has a wide production margin and excellent productivity, but has a problem in display performance, particularly viewing angle characteristics. Specifically, when the display surface of a TN mode liquid crystal display device is observed from an oblique direction, the contrast ratio of the display is significantly reduced, and a plurality of gradations from black to white are clearly observed when observed from the front. When the image is observed from an oblique direction, the problem is that the luminance difference between gradations becomes extremely unclear. Furthermore, the phenomenon that the gradation characteristics of the display are reversed and a darker portion when observed from the front is observed brighter when observed from an oblique direction (so-called gradation inversion phenomenon) is also a problem.

In recent years, liquid crystal display devices with improved viewing angle characteristics in TN mode liquid crystal display devices include in-plane switching mode (IPS mode), multi-domain vertical aligned mode (MVA mode), and axially symmetric alignment mode (ASM). Mode) and the like have been developed. In these novel mode (wide viewing angle mode) liquid crystal display devices, the above-mentioned specific problems related to viewing angle characteristics, that is, a significant reduction in display contrast ratio when the display surface is observed obliquely, and Problems such as display gradation inversion have been solved.

However, under the circumstances where the display quality of liquid crystal display devices is improving, the problem of viewing angle characteristics is that the γ characteristics during frontal observation and the γ characteristics during oblique observation differ, that is, the dependence of γ characteristics on the viewing angle. Sexual problems are newly emerging. Here, the γ characteristic is the gradation dependence of display luminance. When the γ characteristic is different between the front direction and the oblique direction, the gradation display state differs depending on the observation direction. This is particularly problematic when displaying images such as photographs or when displaying TV broadcasts.

As a method for improving the viewing angle dependency of the γ characteristic, two or more subpixels are provided in one pixel, and the luminance of one subpixel is different from the other in the intermediate luminance display. Methods for improving the viewing angle dependency are known (see, for example, Patent Documents 1 and 2). Note that a structure in which each pixel has two or more sub-pixels is also called a multi-pixel structure.

FIG. 23 shows a schematic diagram of a liquid crystal display device 900 disclosed in Patent Document 1. In the liquid crystal display device 900, the

subpixel electrodes

914a and 914b are connected to the common source line S via the

corresponding TFTs

916a and 916b, and form capacitive coupling with the corresponding auxiliary capacitance lines CCSa and CCSb. In the liquid crystal display device 900, when the voltages of the auxiliary capacitance lines CCSa and CCSb that form capacitive coupling with the

subpixel electrodes

914a and 914b change in different modes, the potentials of the

subpixel electrodes

914a and 914b change to change each subpixel. As a result, the viewing angle characteristic is improved. In the liquid crystal display device 900, since the source signal is supplied from the common source line S to the

sub-pixel electrodes

914a and 914b in the same pixel, a decrease in the aperture ratio is suppressed.

Patent Document 2 mentions a color balance shift in a multi-pixel structure. In the liquid crystal display device of Patent Document 2, the voltage difference between the effective voltages of the two subpixels of the blue pixel and / or the cyan pixel is made smaller than the voltage difference of the effective voltages of the two subpixels of the other pixels. Suppresses yellow shift in viewing angle.

JP 2004-62146 A International Publication No. 2008/018552

The suppression effect of whitening can be adjusted by changing the amplitude of the CS signal. In general, as the amplitude of the CS signal is larger, the whitening suppression effect can be increased. However, if the amplitude of the CS signal is increased too much, the display quality from an oblique direction may deteriorate.

The present invention has been made in view of the above problems, and an object thereof is to provide a liquid crystal display device having improved display quality in an oblique direction.

A liquid crystal display device according to an embodiment of the present invention is a liquid crystal display device including a plurality of color display pixels including a first color display pixel and a second color display pixel, and each of the plurality of color display pixels is a first color display pixel. A plurality of pixels including a pixel, a second pixel, and a third pixel; each of the plurality of pixels includes a first subpixel and a second subpixel; and each of the plurality of color display pixels In each of the plurality of pixels, each of the first subpixel and the second subpixel is formed by a counter electrode, a liquid crystal layer, and a subpixel electrode facing the counter electrode via the liquid crystal layer. Liquid crystal capacitance, an auxiliary capacitance electrode electrically connected to the sub-pixel electrode, an insulating layer, and an auxiliary capacitance counter electrode facing the auxiliary capacitance electrode through the insulating layer And the first color of the first color display pixel and the first pixel of the second color display pixel each perform display with at least some intermediate gradation. The voltage difference between the effective voltage of the first sub-pixel and the effective voltage of the second sub-pixel in the first pixel of the display pixel is the effective voltage of the first sub-pixel in the first pixel of the second color display pixel. It is different from the voltage difference between the voltage and the effective voltage of the second subpixel.

In one embodiment, in each of the plurality of pixels of the plurality of color display pixels, the capacitance value of the auxiliary capacitance of the first subpixel is approximately equal to the capacitance value of the auxiliary capacitance of the second subpixel. equal.

In one embodiment, in each of the plurality of pixels of the plurality of color display pixels, the amplitude of the auxiliary capacitance signal supplied to the auxiliary capacitance counter electrode corresponding to the first subpixel is the second subpixel. Is substantially equal to the amplitude of the auxiliary capacitance signal supplied to the auxiliary capacitance counter electrode.

In one embodiment, when each of the first pixel of the first color display pixel and the first pixel of the second color display pixel performs display with at least some intermediate gradation, the first color display pixel of the first color display pixel Write voltages to the subpixel electrodes corresponding to the first subpixel and the second subpixel in the first pixel are the first subpixel and the second subpixel in the first pixel of the second color display pixel. This is different from the write voltage to the subpixel electrode corresponding to.

In one embodiment, the amplitude of the auxiliary capacitance signal supplied to the auxiliary capacitance counter electrode corresponding to the first subpixel and the second subpixel in the first pixel of the first color display pixel is the second color. The amplitude of the auxiliary capacitance signal supplied to the auxiliary capacitance counter electrode corresponding to the first subpixel and the second subpixel in the first pixel of the display pixel is different.

In one embodiment, the capacitance value of the auxiliary capacitance of the first subpixel and the second subpixel in the first pixel of the first color display pixel is equal to the capacity value of the first pixel of the second color display pixel. The capacitance values of the auxiliary capacitors of one subpixel and the second subpixel are substantially equal.

In one embodiment, the capacitance value of the auxiliary capacitance of the first subpixel and the second subpixel in the first pixel of the first color display pixel is equal to the capacity value of the first pixel of the second color display pixel. It differs from the capacitance value of the auxiliary capacitance of one subpixel and the second subpixel.

In one embodiment, the amplitude of the auxiliary capacitance signal supplied to the auxiliary capacitance counter electrode corresponding to the first subpixel and the second subpixel in the first pixel of the first color display pixel is the second color. The amplitude of the auxiliary capacitance signal supplied to the auxiliary capacitance counter electrode corresponding to the first subpixel and the second subpixel in the first pixel of the display pixel is substantially equal.

In one embodiment, the capacitance value of the auxiliary capacitance of the first subpixel and the second subpixel in the first pixel of the first color display pixel is equal to the capacity value of the first pixel of the second color display pixel. Unlike the capacitance values of the auxiliary capacitances of one subpixel and the second subpixel, the auxiliary capacitance counter electrode corresponding to the first subpixel and the second subpixel in the first pixel of the first color display pixel is supplied. The amplitude of the auxiliary capacitance signal is different from the amplitude of the auxiliary capacitance signal supplied to the auxiliary capacitance counter electrode corresponding to the first subpixel and the second subpixel in the first pixel of the second color display pixel. .

In one embodiment, when each of the plurality of pixels of the first color display pixel performs display at the at least certain intermediate gradation, the first subpixel in each of the plurality of pixels of the first color display pixel. And the voltage difference between the effective voltage of the second subpixel and the effective voltage of the second subpixel are substantially equal to each other.

In one embodiment, when each of the plurality of pixels of the first color display pixel performs display at the at least certain intermediate gradation, the first subpixel in each of the plurality of pixels of the first color display pixel. The average effective voltages of the second subpixels are substantially equal to each other.

In one embodiment, the amplitudes of the auxiliary capacitance signals supplied to the auxiliary capacitance counter electrodes corresponding to the first subpixel and the second subpixel in each of the plurality of pixels of the first color display pixel are substantially equal to each other. .

In one embodiment, the capacitance values of the auxiliary capacitors of the first subpixel and the second subpixel in each of the plurality of pixels of the first color display pixel are substantially equal to each other.

In one embodiment, when each of the first pixel and the third pixel of the first color display pixel performs display at the intermediate gray level, the first pixel in the first pixel of the first color display pixel. The voltage difference between the effective voltage of one subpixel and the effective voltage of the second subpixel is the effective voltage of the first subpixel and the effective voltage of the second subpixel in the third pixel of the first color display pixel. And the voltage difference is different.

In one embodiment, the amplitude of the auxiliary capacitance signal supplied to the auxiliary capacitance counter electrode corresponding to the first subpixel and the second subpixel in the first pixel of the first color display pixel is the first color. The amplitude of the auxiliary capacitance signal supplied to the auxiliary capacitance counter electrode corresponding to the first subpixel and the second subpixel in the third pixel of the display pixel is different.

In one embodiment, the capacitance value of the auxiliary capacitance of the first sub-pixel and the second sub-pixel in the first pixel of the first color display pixel is equal to the capacity value of the third pixel of the first color display pixel. This is different from the capacitance value of the auxiliary capacitance of one subpixel and the second subpixel.

In one embodiment, the first pixel, the second pixel, and the third pixel are a red pixel, a green pixel, and a blue pixel, respectively.

In one embodiment, the plurality of color display pixels are arranged in a matrix of a plurality of rows and a plurality of columns, and the second color display pixels are arranged in a row direction or a column direction with respect to the first color display pixels. Adjacent.

The liquid crystal display device according to the embodiment of the present invention can improve the display quality in the oblique direction.

(A) is a schematic diagram of 1st Embodiment of the liquid crystal display device by this invention, (b) is a schematic diagram of four color display pixels in the liquid crystal display device of this embodiment. FIG. 4 is an equivalent circuit diagram of one pixel in the liquid crystal display device of the present embodiment. It is a signal waveform diagram in the liquid crystal display device of this embodiment. It is a schematic diagram which shows the voltage difference of the effective voltage of four color display pixels and the sub pixel in each pixel in the liquid crystal display device of this embodiment. (A) is a schematic diagram of the liquid crystal display device of a comparative example, (b) is a schematic diagram of four color display pixels in the liquid crystal display device of the comparative example. It is a graph which shows the viewing angle characteristic from the diagonal direction in the liquid crystal display device of a comparative example. It is a graph which shows the viewing angle characteristic from the diagonal direction in the liquid crystal display device of this embodiment. It is a graph which shows the viewing angle characteristic from the diagonal direction in the liquid crystal display device of this embodiment. It is an equivalent circuit diagram of four color display pixels in the liquid crystal display device of the present embodiment. It is an equivalent circuit diagram of four color display pixels in the liquid crystal display device of the present embodiment. It is an equivalent circuit diagram of four color display pixels in the liquid crystal display device of the present embodiment. It is a schematic diagram which shows the voltage difference of the effective voltage of four color display pixels and the sub pixel in each pixel in the liquid crystal display device of this embodiment. It is a schematic diagram which shows the voltage difference of the effective voltage of four color display pixels and the sub pixel in each pixel in the liquid crystal display device of this embodiment. It is a schematic diagram which shows the voltage difference of the effective voltage of four color display pixels and the sub pixel in each pixel in the liquid crystal display device of this embodiment. It is a schematic diagram which shows the effective voltage difference of four color display pixels and each pixel in 2nd Embodiment of the liquid crystal display device by this invention. It is a schematic diagram which shows the full width of four color display pixels in the liquid crystal display device of a comparative example, and the CS signal corresponding to the auxiliary capacity of each pixel. FIG. 16A is a graph showing changes in chromaticity u ′ with respect to gradation changes in the liquid crystal display device shown in FIG. 16, and FIG. 16B is a graph showing changes in chromaticity v ′ with changes in gradation. It is a schematic diagram which shows the full width of four color display pixels in the liquid crystal display device of a comparative example, and the CS signal corresponding to the auxiliary capacity of each pixel. 18A is a graph showing changes in chromaticity u ′ with respect to gradation changes in the liquid crystal display device shown in FIG. 18, and FIG. 18B is a graph showing changes in chromaticity v ′ with changes in gradation. It is a schematic diagram which shows the full width of four color display pixels in the liquid crystal display device of this embodiment, and the CS signal corresponding to the auxiliary capacity of each pixel. 20A is a graph showing changes in chromaticity u ′ with respect to gradation changes in the liquid crystal display device shown in FIG. 20, and FIG. 20B is a graph showing changes in chromaticity v ′ with changes in gradation. It is a schematic diagram which shows ratio of the capacitance value of four color display pixels and the auxiliary capacitance of each pixel in the liquid crystal display device of this embodiment. It is a schematic diagram of the pixel in the conventional liquid crystal display device.

Hereinafter, embodiments of a liquid crystal display device according to the present invention will be described with reference to the drawings. However, the present invention is not limited to the following embodiments.

(Embodiment 1)
Hereinafter, a liquid crystal display device 100 according to a first embodiment of the present invention will be described with reference to the drawings. FIG. 1A shows a schematic diagram of a liquid crystal display device 100 of the present embodiment. The liquid crystal display device 100 includes a rear substrate 10, a front substrate 20, and a liquid crystal layer 30 provided between the rear substrate 10 and the front substrate 20. The back substrate 10 has an insulating substrate 12 and pixel electrodes 14. The front substrate 20 has an insulating substrate 22 and a counter electrode 24. Although not shown here, typically, the back substrate 10 includes a source line, an insulating layer, a gate line, a switching element (typically, a thin film transistor (TFT)) and an alignment film. The front substrate 20 is provided with a color filter layer, an alignment film, and the like. A polarizing plate is provided outside the rear substrate 10 and the front substrate 20.

For example, the liquid crystal display device 100 is in a VA (Vertical Alignment) mode. Specifically, the liquid crystal display device 100 may be in an MVA (Multi-domain Vertical Alignment) mode, a PVA (Patterned Vertical Alignment) mode, or a CPA (Continuous Pinweal Alignment) mode, or an RTN (Welte Current). It may be a mode. For example, the RTN mode may specifically be a UV ² A (Ultraviolet-induced multi-domain Vertical Alignment) mode. In this case, the liquid crystal layer 30 is a vertical alignment type liquid crystal layer, and the alignment film is a vertical alignment film. Here, the “vertical alignment type liquid crystal layer” refers to a liquid crystal layer in which a liquid crystal molecular axis (also referred to as “axis orientation”) is aligned at an angle of about 85 ° or more with respect to the surface of the vertical alignment film. Typically, display is performed in a normally black mode by combining the liquid crystal layer 30 and a polarizing plate arranged in crossed Nicols. Alternatively, the liquid crystal display device 100 may be in a TN (Twisted Nematic) mode.

Further, the liquid crystal display device 100 may be a transmissive type or a reflective type. Alternatively, the liquid crystal display device 100 may be a transmission / reflection type. In the case of the transmissive type or the transmissive / reflective type, the liquid crystal display device 100 further includes a backlight.

The liquid crystal display device 100 is provided with a plurality of color display pixels. The color display pixel functions as a display unit of an arbitrary color. The color display pixel has three or more pixels. For example, when red, green, and blue are used as primary colors, the color display pixel has a red pixel, a green pixel, and a blue pixel. Each pixel is defined by a pixel electrode 14. The counter electrode 24 is typically provided so as to oppose all the pixel electrodes 14, but may be provided by being divided into a plurality of blocks.

FIG. 1B shows a schematic diagram of four color display pixels D in the liquid crystal display device 100. In the liquid crystal display device 100, a plurality of color display pixels are arranged in a matrix of a plurality of rows and a plurality of columns. FIG. 1B shows four color display pixels D ₁ to D ₄ . . The color display pixels D ₁ and D ₂ are adjacent in the row direction (x direction), and the color display pixels D ₃ and D ₄ are adjacent in the row direction. The color display pixels D ₁ and D ₃ are adjacent to each other in the column direction (y direction), and the color display pixels D ₂ and D ₄ are adjacent to each other in the column direction.

Each color display pixel D has a plurality of pixels. Here, the plurality of pixels include a red pixel R, a green pixel G, and a blue pixel B. In this specification, the red pixel, the green pixel, and the blue pixel of the color display pixel D ₁ may be referred to as a red pixel R ₁ , a green pixel G _1, and a blue pixel B ₁ . Similarly, in each of the color display pixels D ₂ , D ₃ , and D ₄ , red pixels are red pixels R ₂ , R ₃ , R ₄ , green pixels are green pixels G ₂ , G ₃ , G ₄ , and blue pixels are blue pixels. B ₂ , B ₃ , and B ₄ may be indicated respectively.

Each pixel R, G, B has a sub-pixel a and a sub-pixel b. Here, the sub-pixel a and the sub-pixel b have substantially the same area, and the sub-pixel a and the sub-pixel b exhibit different luminances at least in a certain intermediate gradation. In this specification, the subpixels a and b may be referred to as a first subpixel and a second subpixel, respectively. In this specification, may indicate red pixel R _1, green pixel G ₁ and blue pixel sub-pixel a respective subpixels R _1a of B _1, and G _1a and B _1a, the red pixels R _1, green pixel G ₁ And the sub-pixel b of the blue pixel B ₁ may be denoted as sub-pixels R _1b , G _1b and B _1b , respectively. Similarly, the red pixel _{_{_{R 2, R 3, R 4}}} , a green pixel G _2, G _3, G ₄ and the blue pixel B _2, B _3, sub-pixel a respective subpixels R _2a of B _4, R _3a, R _4a , _G2a , _G3a , _G4a , _B2a , _B3a , _B4a, and these subpixels b are subpixels _R2b , _R3b , _R4b , _G2b , _G3b , _G4b , B, respectively. _2b , B _3b , B _4b may be indicated.

FIG. 2 shows an equivalent circuit of one pixel of the liquid crystal display device 100. Here, the liquid crystal layers 30 corresponding to the sub-pixels a and b are represented as

liquid crystal layers

30a and 30b. The pixel electrode 14 is separated into

subpixel electrodes

14a and 14b, while the counter electrode 24 is typically common to both subpixels a and b.

The liquid crystal capacitor CLa of the subpixel a is formed by the subpixel electrode 14a, the counter electrode 24, and the liquid crystal layer 30a, and the liquid crystal capacitor CLb of the subpixel b is formed of the subpixel electrode 14b, the counter electrode 24, and the liquid crystal layer. 30b. Here, the capacitance values of the liquid crystal capacitors CLa and CLb are expressed as CL (V). CL (V) depends on the effective voltage V applied to the

liquid crystal layers

30a and 30b.

The auxiliary capacitor CSa of the subpixel a is formed by an auxiliary capacitor electrode, an auxiliary capacitor counter electrode, and an insulating layer, and the auxiliary capacitor CSb of the subpixel b is formed of an auxiliary capacitor electrode, an auxiliary capacitor counter electrode, and an insulating layer. Formed by. Here, the capacitance values of the auxiliary capacitors CSa and CSb are the same value, and this value is represented as CCS.

In the subpixel a, one electrode of each of the liquid crystal capacitor CLa and the auxiliary capacitor CSa is connected to the drain of the TFT 16a functioning as a switching element of the subpixel a, and the other electrode of the liquid crystal capacitor CLa is connected to the counter electrode 24. The other electrode of the auxiliary capacitor CSa is connected to the auxiliary capacitor line (CS line) CCSa. In the sub-pixel b, one electrode of each of the liquid crystal capacitor CLb and the auxiliary capacitor CSb is connected to the drain of the TFT 16b functioning as a switching element of the sub-pixel b, and the other electrode of the liquid crystal capacitor CLb is the counter electrode 24. The other electrode of the auxiliary capacitor CSb is connected to an auxiliary capacitor line (CS line) CCSb. The gates of the

TFTs

16 a and 16 b are both connected to the gate line G, and the sources are both connected to the source line S.

Note that the thicknesses of the

liquid crystal layers

30a and 30b of the sub-pixels a and b of the red pixel R, the green pixel G, and the blue pixel B are substantially constant unless otherwise specified. However, the present invention is not limited to this.

FIG. 3 schematically shows changes in each voltage for driving the liquid crystal display device 100 of the present embodiment within a certain vertical scanning period. In FIG. 3, Vs indicates the voltage of the source line S, Vcsa indicates the voltage of the CS line CCSa, Vcsb indicates the voltage of the CS line CCSb, Vg indicates the voltage of the gate line G, and VLa indicates the subpixel electrode 14a. VLb indicates the voltage of the sub-pixel electrode 14b. Further, the broken line in the figure indicates the voltage COMMON (Vc) of the counter electrode 24. The voltage Vcsa of the CS wiring CCSa periodically changes in the range from Vc−Vad to Vc + Vad, and the voltage Vcsb of the CS wiring CCSb also periodically changes in the range of Vc−Vad to Vc + Vad. The amplitude of the voltage Vcsb of the CS wiring CCSb is equal to the voltage Vcsa of the CS wiring CCSa, and the phase of the voltage Vcsb of the CS wiring CCSb is 180 degrees different from the voltage Vcsa of the CS wiring CCSa.

Hereinafter, the operation of the equivalent circuit shown in FIG. 2 will be described with reference to FIG.

At time T1, the voltage Vg of the gate line G changes from VgL to VgH, so that the

TFTs

16a and 16b are simultaneously turned on (on state), and the source line S is connected to the

subpixel electrodes

14a and 14b of the subpixels a and b. The voltage Vs is transmitted, and the liquid crystal capacitors CLa and CLb of the sub-pixels a and b are charged. Similarly, the auxiliary capacitors CSa and CSb of the respective sub-pixels are charged from the source line S. Note that the voltage Vs of the source line S at this time is also referred to as a write voltage.

Next, when the voltage Vg of the gate line G changes from VgH to VgL at time T2, the

TFTs

16a and 16b are simultaneously turned off (off state), and the liquid crystal capacitors CLa and CLb of the sub-pixels a and b, the auxiliary The capacitors CSa and CSb are both electrically insulated from the source line S. Immediately after this, due to the pull-in phenomenon due to the influence of the parasitic capacitance etc. of the

TFTs

16a and 16b, the voltages VLa and VLb of the

sub-pixel electrodes

14a and 14b are lowered by substantially the same voltage Vd,
VLa = Vs−Vd
VLb = Vs−Vd
It becomes. At this time, the voltages Vcsa and Vcsb of the respective CS lines CCSa and CCSb are Vcsa = Vc−Vad
Vcsb = Vc + Vad
It is.

At time T3, the voltage Vcsa of the CS wiring CCSa connected to the auxiliary capacitor CSa increases by 2 × Vad from Vc−Vad to Vc + Vad, and the voltage Vcsb of the CS wiring CCSb connected to the auxiliary capacitor CSb increases from Vc + Vad to Vc−. Decrease to Vad by 2 × Vad. With the voltage change of the CS wirings CCSa and CCSb, the voltages VLa and VLb of the

subpixel electrodes

14a and 14b are respectively
VLa = Vs−Vd + 2 × K × Vad
VLb = Vs−Vd−2 × K × Vad
To change. However, K = CCS / (CL (V) + CCS).

At time T4, the voltage Vcsa of the CS line CCSa changes from Vc + Vad to Vc−Vad, and the voltage Vcsb of the CS line CCSb changes from Vc−Vad to Vc + Vad by 2 × Vad, thereby causing the

subpixel electrodes

14a and 14b to change. The voltages VLa and VLb are
VLa = Vs−Vd + 2 × K × Vad
VLb = Vs−Vd−2 × K × Vad
From
VLa = Vs−Vd
VLb = Vs−Vd
To change.

At time T5, the voltage Vcsa of the CS wiring CCSa changes from Vc−Vad to Vc + Vad, the voltage Vcsb of the CS wiring CCSb changes from Vc + Vad to Vc−Vad by 2 × Vad, and the voltages VLa of the

subpixel electrodes

14a and 14b are changed. VLb is also
VLa = Vs−Vd
VLb = Vs−Vd
From
VLa = Vs−Vd + 2 × K × Vad
VLb = Vs−Vd−2 × K × Vad
To change.

Vcsa, Vcsb, VLa, and VLb alternately repeat the changes in T4 and T5 at intervals of an integral multiple of the horizontal scanning time 1H. Whether the repetition interval of T4 and T5 is set to 1 time, 1 time, 2 times, 3 times, or more than 1H depends on the driving method (polarity inversion method, etc.) of the liquid crystal display device and the display state ( It may be set as appropriate in consideration of flickering, display roughness, and the like. This repetition is continued until the pixel is next rewritten, that is, until a time equivalent to T1 is reached. Therefore, the average voltages VLa and VLb of the

subpixel electrodes

14a and 14b are respectively
VLa = Vs−Vd + K × Vad
VLb = Vs−Vd−K × Vad
It becomes.

Therefore, the effective voltages V1 and V2 applied to the

liquid crystal layers

30a and 30b of the subpixels a and b are opposite to the difference between the voltage of the subpixel electrode 14a and the voltage of the counter electrode 24, and the voltage of the subpixel electrode 14b, respectively. Difference from the voltage of the electrode 24, ie
V1 = VLa-Vcom
V2 = VLb-Vcom
That is,
V1 = Vs−Vd + K × Vad−Vcom
V2 = Vs−Vd−K × Vad−Vcom
It becomes. Accordingly, the effective voltage difference ΔV (= V1−V2) applied to the

liquid crystal layers

30a and 30b of the sub-pixels a and b is ΔV = 2 × K × Vad (where K = CCS / (CL (V ) + CCS)), and different voltages can be applied to the

liquid crystal layers

30a and 30b. In addition, when the amount of potential change from the maximum value to the minimum value of the potential of the CS signal is expressed as ΔVad (= 2 × Vad), it is expressed as ΔV = K × ΔVad. This ΔVad is also called the peak-to-peak or full width of the CS signal. Typically, the smaller the value of the voltage V1, the larger the value of ΔV. The value of ΔV changes depending on V1 or V2 because the capacitance value CL (V) of the liquid crystal capacitance changes depending on the voltage. As described above, the voltages of the sub-pixels a and b in one pixel can be made different.

In the liquid crystal display device 100 of this embodiment, the voltage difference between the effective voltage of the sub-pixel a and the effective voltage of the sub-pixel b is varied according to the color display pixel D, thereby further improving the viewing angle characteristics. ing.

FIG. 4 shows the voltage difference between the effective voltage of the sub-pixel a and the effective voltage of the sub-pixel b in the color display pixels D ₁ to D ₄ and each pixel in the liquid crystal display device 100 of the present embodiment. Here, the colors displayed by the four color display pixels D ₁ to D _{4 in} the input signal are equal to each other. Further, in each of the color display pixels D ₁ to D ₄ , the red pixel R, the green pixel G, and the blue pixel B exhibit the same intermediate gradation, and for example, the color display pixels D ₁ to D ₄ exhibit an achromatic color. In order to avoid an excessively complicated description, it is assumed here that the same source signal voltage is applied to each source line according to the polarity.

Here, in the red pixel R ₁ of the color display pixel D ₁ , the voltage difference between the effective voltage of the sub-pixel R _{1a and} the effective voltage of the sub-pixel R _1b is ΔV ₁ . Further, the voltage difference between the effective voltage of the sub-pixel G _{1a and} the effective voltage of the sub-pixel G _{1b in} the green pixel G ₁ is also ΔV ₁ , and the effective voltage of the sub-pixel B _{1a and} the effective voltage of the sub-pixel B _{1b in} the blue pixel B ₁ The voltage difference from the effective voltage is also ΔV ₁ .

In contrast, in the red pixel R ₂ of the color display pixel D ₂ , the voltage difference between the effective voltage of the sub-pixel R _{2a and} the effective voltage of the sub-pixel R _2b is ΔV ₂ , and ΔV ₂ is different from ΔV ₁ . Further, the voltage difference between the effective voltage of the sub-pixel G _{2a and} the effective voltage of the sub-pixel G _{2b in} the green pixel G ₂ is also ΔV ₂ , and the effective voltage of the sub-pixel B _{2a and} the effective voltage of the sub-pixel B _{2b in} the blue pixel B ₂ . The voltage difference from the effective voltage is also ΔV ₂ .

For each of the red pixel R ₃ , the green pixel G ₃ , and the blue pixel B ₃ of the color display pixel D ₃ , the voltage difference between the effective voltage of the sub-pixel a and the effective voltage of the sub-pixel b is ΔV _2. For each of the red pixel R ₄ , the green pixel G ₄ , and the blue pixel B ₄ of the display pixel D ₄ , the voltage difference between the effective voltage of the sub-pixel a and the effective voltage of the sub-pixel b is ΔV ₁ . In FIG. 4, the color display pixel D in which the voltage difference between the effective voltages of the sub-pixels a and b is ΔV ₁ is diagonally adjacent, and the voltage difference between the effective voltages of the sub-pixels a and b is ΔV _2. The color display pixels D are adjacent obliquely. Thus, the difference in effective voltage difference ΔV between the sub-pixels a and b in the adjacent color display pixels D improves the viewing angle characteristics effectively.

For example, the sub-pixels a, the voltage difference [Delta] V ₁ of b in the color display pixel D ₁ is represented as _{_{_{ΔV 1 = K 1 × ΔVad 1}}} . Here, K ₁ is expressed as K ₁ = CCS ₁ / (CL (V) + CCS ₁ ). DerutaVad ₁ is a potential change of color display pixels each pixel R ₁ in D _1, G _1, sub-pixel B ₁ a, b of the auxiliary capacitor CSa, CS signals corresponding to CSb (full width), CCS ₁ is subpixel a in the color display pixel D _1, b of the auxiliary capacitor CSa, a capacitance value of CSb.

Similarly, sub-pixel a, the voltage difference [Delta] V ₂ of b in the color display pixel D ₂ is represented as _{_{_{ΔV 2 = K 2 × ΔVad 2}}} . Here, K ₂ is expressed as K ₂ = CCS ₂ / (CL (V) + CCS ₂ ), and ΔVad ₂ is the sub-pixel a, b of each pixel R ₂ , G ₂ , B _{2 in} the color display pixel D ₂ . The CS signal potential change amount corresponding to the auxiliary capacitors CSa and CSb, and CCS ₂ is the capacitance value of the auxiliary capacitors CSa and CSb of the sub-pixels a and b in the color display pixel D ₂ .

From the above
ΔV ₁ = K ₁ × ΔVad ₁
ΔV ₂ = K ₂ × ΔVad ₂
It is expressed.

Details will be described later, each pixel of the color display pixel D _1, D ₂ R, subpixel a G and B, b of the auxiliary capacitance CSa, by varying the capacitance values CCS _1, CCS ₂ of CSb, color display Depending on the pixel D, the voltage difference ΔV between the effective voltages of the sub-pixels a and b can be made different. Specifically, the overlapping area of the auxiliary capacitance electrodes and auxiliary capacitance counter electrodes forming the auxiliary capacitances CSa and CSb of the sub-pixels a and b of the red pixel R, the green pixel G, and the blue pixel B is defined in the color display pixel D. It may be different depending on the situation. Alternatively, the values of K ₁ and K ₂ may be made different by making the liquid crystal capacitance CL different by changing the gap (thickness) of the liquid crystal layer according to the color display pixel D. Alternatively, in the color display pixels D ₁ and D ₂ , the auxiliary capacitance signals (CS signals) supplied to the auxiliary capacitance counter electrodes of the auxiliary capacitances CSa and CSb of the subpixels a and b of the red pixel R, green pixel G, and blue pixel B, respectively. ) Amplitudes Vad ₁ and Vad ₂ (or potential change amounts ΔVad ₁ and ΔVad ₂ ) may be made different according to the color display pixels D ₁ and D ₂ . Alternatively, each pixel in the color display pixel D _1, D ₂ R, subpixel a G and B, b of the auxiliary capacitance CSa, K ₁ and K represented by the capacitance value CCS _1, CCS ₂ and the liquid crystal capacitance CL of CSb _{In addition} to making the value of ₂ different, the amplitudes Vad ₁ and Vad ₂ (or potential change amounts ΔVad ₁ and ΔVad ₂ ) of the auxiliary capacitance signal (CS signal) may be made different.

Thus, by making the voltage difference between the effective voltages of the sub-pixels in the pixels displaying the same color at least two types, the diagonal γ characteristics of the pixels displaying this color can be changed not only in the sub-pixel unit but also in the pixel unit. The viewing angle characteristics can be improved.

As in a typical liquid crystal display device, in the liquid crystal display device 100, the magnitude relationship between the potentials of the pixel electrode 14 and the counter electrode 24 among the voltages applied to the liquid crystal layer 30 is inverted at regular intervals, and the liquid crystal display device 100 is liquid crystal. The direction of the electric field applied to the layer 30 (the direction of the electric lines of force) is set so as to be reversed at regular intervals. The direction of the electric field is also called polarity. For example, when focusing on a certain pixel, after writing is performed so that the potential of the pixel electrode 14 is higher than that of the counter electrode 24 in a certain vertical scanning period, the potential of the counter electrode 24 is changed in another vertical scanning period. Writing is performed so as to be higher than the pixel electrode 14. Typically, the pixel writing polarity is inverted every vertical scanning period.

Further, when paying attention to the polarities of a plurality of pixels in a specific vertical scanning period, pixels having one polarity are arranged in a checkered pattern, and pixels having the other polarity are also arranged in a checkered pattern. Further, when paying attention to the brightness of subpixels in a specific vertical scanning period, if a subpixel brighter than the other pixel in the same pixel is called a bright subpixel, the bright subpixels are arranged in a checkered pattern. Note that the brightness of the sub-pixels may be inverted within the same pixel.

Hereinafter, advantages of the liquid crystal display device 100 of the present embodiment compared to the liquid crystal display device 800 of the comparative example will be described. First, a liquid crystal display device 800 of a comparative example will be described.

FIG. 5A shows a schematic diagram of the liquid crystal display device 800. The liquid crystal display device 800 includes a rear substrate 810, a front substrate 820, and a liquid crystal layer 830 provided between the rear substrate 810 and the front substrate 820. The back substrate 810 includes an insulating substrate 812 and pixel electrodes 814. The front substrate 820 includes an insulating substrate 822 and a counter electrode 824.

FIG. 5B shows a schematic diagram of _four color display pixels D ₁ to D ₄ in the liquid crystal display device 800. Again, the colors displayed by the four color display pixels D ₁ to D _{4 in} the input signal are equal to each other. In each of the color display pixels D ₁ to D ₄ , the red pixel R, the green pixel G, and the blue pixel B exhibit the same intermediate gradation, and the color display pixels D ₁ to D ₄ exhibit an achromatic color.

In the liquid crystal display device 800, the voltage difference between the effective voltage of the sub-pixel R _{1a and} the effective voltage of the sub-pixel R _1b in the red pixel R ₁ of the color display pixel D ₁ is ΔVc. Further, the voltage difference between the effective voltage of the sub-pixel G _{1a and} the effective voltage of the sub-pixel G _{1b in} the green pixel G ₁ is also ΔVc, and the effective voltage of the sub-pixel B _{1a and} the effective voltage of the sub-pixel B _{1b in} the blue pixel B ₁ . The voltage difference from the voltage is also ΔVc. Similarly, in each of the red pixels R, green pixels G, and blue pixels B of the color display pixels D ₂ , D ₃ , and D ₄ , the voltage difference between the effective voltage of the subpixel a and the effective voltage of the subpixel b is also ΔVc. As described above, when the voltage difference ΔVc between the effective voltages of the sub-pixels a and b is constant in the color display pixels D ₁ to D ₄ , the viewing angle characteristics are not sufficiently improved.

FIG. 6 shows a graph showing the viewing angle characteristics of the liquid crystal display device 800. Here, the amplitude (full width) of the CS signal is changed, and the full width of the CS signal is one of 0V, 2.0V, 3.0V, and 4.0V.

Here, the number of gradations of each pixel is 255. In FIG. 6, the horizontal axis (x-axis) indicates the front normalized luminance of γ = 2.2 corresponding to the gradations 0 to 255. In general, the liquid crystal display device is set to show a curve of γ = 2.2 when observed from the front. In the liquid crystal display device 800, gradations 0 to 255 are proportional to the front normalized luminance. is doing.

In FIG. 6, the vertical axis (y-axis) indicates 45 ° viewing angle normalized luminance of γ = 2.2 corresponding to gradations 0 to 255. In FIG. 6, an ideal case where 45 ° viewing angle normalized luminance is equal to front normalized luminance and changes when γ = 2.2 is indicated as γ = 2.2. Here, the liquid crystal display device 800 is in the 4DRTN mode.

When the total width of the CS signal is 0V, that is, when the effective voltages of the sub-pixels a and b in each pixel are equal, as shown in FIG. The difference between the luminance and the front normalized luminance is considerably large, and the 45 ° viewing angle normalized luminance is considerably larger than the front normalized luminance. Thus, since the normalized luminance in the oblique direction is relatively higher than the normalized luminance in the front direction, the display viewed from the oblique direction looks whitish. Such a phenomenon is also called whitening.

When the full width of the CS signal is 2.0 V, the difference between the 45 ° viewing angle normalized luminance and the front normalized luminance becomes small. In particular, the 45 ° viewing angle normalized luminance is close to the front normalized luminance over the gradations 20 to 160, thereby suppressing whitening.

When the total width of the CS signal is 3.0 V, the difference between the 45 ° viewing angle normalized luminance and the front normalized luminance is smaller than that when the total width is 2.0 V, and in particular, 45 degrees over gradations 100 to 160. The viewing angle normalized luminance is closer to the front normalized luminance. In addition, when the total width of the CS signal is 4.0 V, the difference between the 45 ° viewing angle normalized luminance and the front normalized luminance is further reduced as compared with the case where the total width is 3.0 V, and the 45 tones in the gradations 130 to 160 are 45. The degree viewing angle normalized luminance is closer to the front normalized luminance. Thus, as the full width of the CS signal increases, the 45 ° viewing angle normalized luminance tends to approach the front normalized luminance, thereby suppressing whitening.

Up to this point, attention has been paid to the difference between the front normalized luminance and the 45 ° viewing angle normalized luminance. Here, the 45 ° viewing angle normalized luminance change with respect to the gradation change (that is, the gradation change from the 45 ° viewing angle direction). ) Focus on itself. Although the variation of the change rate of 45 degree viewing angle normalized luminance with respect to the gradation change when the CS signal full width is 2.0V is relatively small, the 45 degree viewing angle with respect to the gradation change when the CS signal full width is 3.0V. The variation of the change rate of the normalized luminance is larger than that when the full width of the CS signal is 2.0V. In addition, the variation in the change rate of the 45-degree viewing angle normalized luminance with respect to the gradation change when the full width of the CS signal is 4.0V is larger than that when the full width of the CS signal is 3.0V. As described above, in the liquid crystal display device 800, when the full width of the CS signal is larger than a certain value, the change rate of the normalized luminance in the oblique direction with respect to the gradation change may fluctuate greatly, and the display quality may be deteriorated. On the other hand, in the liquid crystal display device 100 of this embodiment, the fluctuation | variation of the change rate of the normalization brightness | luminance of the diagonal direction is suppressed, and the fall of display quality is suppressed.

FIG. 7 shows a graph showing the viewing angle characteristics of the liquid crystal display device 100. In FIG. 7, the horizontal axis (x-axis) indicates the front normalized luminance of γ = 2.2 corresponding to the gradations 0 to 255. In the liquid crystal display device 100 as well, gradations 0 to 255 are proportional to the front normalized luminance. In FIG. 7, the vertical axis (y-axis) indicates 45 ° viewing angle normalized luminance of γ = 2.2 corresponding to gradations 0 to 255. Further, the liquid crystal display device 100 is in the 4DRTN mode.

Here, in the liquid crystal display device 100, the auxiliary capacitors CSa and CSb of the sub-pixels a and b of the pixels R, G, and B in each color display pixel D are substantially constant, but depending on the color display pixel D, the pixels R, G The widths of the CS signals corresponding to the auxiliary capacitors CSa and CSb of the B subpixels a and b are different. Here, there are two types of CS signal full width, one full width is 2.0V, and the other full width is 4.0V. For reference, FIG. 7 shows a case where the full width of the CS signal in the liquid crystal display device 800 of the comparative example described above with reference to FIG. 6 is set to any one of 0V, 2.0V, 3.0V, and 4.0V. The 45-degree viewing angle normalized luminance change is also shown.

As can be understood from FIG. 7, in the liquid crystal display device 100, the difference between the 45 ° viewing angle normalized luminance and the front normalized luminance is small compared to the case where the entire width of the CS signal in the liquid crystal display device 800 is 0V. The 45-degree viewing angle normalized luminance is close to the front normalized luminance in the keys 100 to 160. Similarly, in the liquid crystal display device 100, the difference between the 45 ° viewing angle normalized luminance and the front normalized luminance is small compared to the case where the entire width of the CS signal in the liquid crystal display device 800 is 2.0V, and the gradations 100 to 160 are small. Over 45 degrees, the viewing angle normalized luminance approaches the front normalized luminance.

In the liquid crystal display device 100, the difference between the 45 ° viewing angle normalized luminance and the front normalized luminance is slightly larger than that in the liquid crystal display device 800 when the full width of the CS signal is 3.0V or 4.0V. In the liquid crystal display device 100 of the present embodiment, the variation in the change rate of the 45-degree viewing angle normalized luminance with respect to the gradation change over the gradations 100 to 160 is smaller than when the full width of the CS signal is 3.0V or 4.0V. This makes it possible to smoothly change the 45-degree viewing angle normalized luminance with respect to the gradation change. As described above, the display quality in the oblique direction can be further improved by providing the color display pixels D having different voltage differences ΔV of the effective voltages of the sub-pixels a and b.

In addition, with reference to FIG. 7, although the viewing angle characteristic from the direction of 45 degrees diagonally was demonstrated, the same tendency is shown also in another angle.

FIG. 8 is a graph showing the viewing angle characteristics of the liquid crystal display device 100. In FIG. 8, the horizontal axis (x-axis) indicates the front normalized luminance of γ = 2.2 corresponding to the gradations 0 to 255. As described above, also in the liquid crystal display device 100, the gradations 0 to 255 are proportional to the front normalized luminance. In FIG. 8, the vertical axis (y-axis) indicates 60 ° viewing angle normalized luminance of γ = 2.2 corresponding to gradations 0 to 255.

Also here, in the liquid crystal display device 100, the auxiliary capacitors CSa and CSb of the sub-pixels a and b of the pixels R, G and B in each color display pixel D are constant, but the pixels R, G, and B according to the color display pixel D are constant. The full widths of the CS signals corresponding to the auxiliary capacitors CSa and CSb of the B subpixels a and b are different. There are two types of CS signal full width. One full width is 2.0V and the other full width is 4.0V. Also here, the liquid crystal display device 100 is in the 4DRTN mode. For reference, in FIG. 8, the full width of the CS signal in the liquid crystal display device 800 of the comparative example described above with reference to FIG. 6 is changed to 2.0 V, 3.0 V, and 4.0 V (that is, CS It also shows the change in 60 ° viewing angle normalized luminance when the signal amplitude is changed at 1.0V, 1.5V, and 2.0V.

As in FIG. 7, in FIG. 8, in the liquid crystal display device 800, when the full width of the CS signal is 3.0V, it is 60 degrees over the gradations 100 to 170, compared with the case where the full width of the CS signal is 2.0V. The viewing angle normalized luminance is closer to the front normalized luminance. Further, when the full width of the CS signal is 4.0 V, the 60-degree viewing angle normalized luminance is closer to the front normalized luminance over the gradations 130 to 170, compared to the case where the full width of the CS signal is 3.0 V. Thus, as the full width of the CS signal increases, the 60 ° viewing angle normalized luminance tends to approach the front normalized luminance, and whitening can be suppressed.

However, paying attention to the change in 60-degree viewing angle normalized luminance itself, when the entire width of the CS signal becomes larger than a certain value, the change rate of the 60-degree viewing angle normalized brightness with respect to the gradation change greatly varies. The variation in the rate of change of the 60 ° viewing angle normalized luminance with respect to the gradation change when the full width of the CS signal is 3.0V is larger than that when the full width of the CS signal is 2.0V. Further, the variation in the change rate of the 60 ° viewing angle normalized luminance with respect to the gradation change when the full width of the CS signal is 4.0V is larger than that when the full width of the CS signal is 3.0V.

On the other hand, in the liquid crystal display device 100 of the present embodiment, the voltage difference ΔV of the effective voltages of the sub-pixels a and b is varied according to the color display pixel D. For this reason, the variation in the change rate of the 60-degree viewing angle normalized luminance with respect to the gradation change over the gradations 100 to 170 is smaller than that of the liquid crystal display device 800 in which the full width of the CS signal is 3.0V, 4.0V. As described above, in the liquid crystal display device 100, the change in the change rate of the 60-degree viewing angle normalized luminance is suppressed, and the change in the normalized luminance in the oblique direction with respect to the gradation change can be smoothed.

7 and 8 show the results when the full width of one of the two full widths is 2.0 V and the full width of the other is 4.0 V in the liquid crystal display device 100 of the present embodiment. Yes. 7 and 8 show results when the full width of the CS signal is 3.0 V, which is the average of 2.0 V and 4.0 V, in the liquid crystal display device 800 of the comparative example. As understood from the comparison of these results, even if the entire width of the CS signal is an average value of the two values, the sub-pixels a and b of all the color display pixels D as in the liquid crystal display device 800 of the comparative example are used. If the effective voltage difference ΔV is constant, the display quality in the oblique direction is not sufficiently improved. On the other hand, in the liquid crystal display device 100, the voltage difference ΔV between the effective voltages of the sub-pixels a and b differs depending on the color display pixel D, thereby improving the display quality in the oblique direction.

Although not shown in FIGS. 7 and 8, when the full width of the CS signal is 1.0 V, the viewing angle characteristics from the oblique direction are slightly improved as compared with the case where the full width is zero. When the total width is less than 1.0 V, there is almost no improvement effect. In addition, when the entire width of the CS signal exceeds 5.0 V, the variation in the change rate of the normalized luminance in the oblique direction is further increased, and the display quality is greatly deteriorated. For this reason, it is preferable that the amplitudes Vad ₁ and Vad ₂ are different from each other and that 1/5 <Vad ₂ / Vad ₁ <5. If the amplitude Vad ₂ is larger than the amplitude Vad ₁ , it is preferable that 1 <Vad ₂ / Vad ₁ <5. Since the amplitude is proportional to the potential variation (full width) DerutaVad, potential variation DerutaVad _1, Similarly for DerutaVad _2, the potential variation ΔVad _1, ΔVad ₂ are different from each other, _{and, 1/5 <ΔVad 2 /} ΔVad 1 <5 is preferred. If the potential change amount ΔVad ₂ is larger than the potential change amount ΔVad ₁ , it is preferable that 1 <ΔVad ₂ / ΔVad ₁ <5.

When attention is paid to the voltage differences ΔV ₁ and ΔV ₂ of the effective voltages of the sub-pixels a and b in the color display pixels D ₁ and D ₂ , ΔV ₁ and ΔV ₂ are different from each other and 1/5 <ΔV ₂ / ΔV ₁ < 5 is preferable. Also, if [Delta] V ₂ is greater than [Delta] V _1, 1 <is preferably ΔV ₂ / ΔV ₁ <5.

Here, each of the sub-pixel a color display pixel D _1, D _2, b of the auxiliary capacitance CSa, the capacitance value of CSb CCS _1, CCS ₂ is equal Accordingly, equal K _1, K _2, In addition, although the potential change amounts ΔVad ₁ and ΔVad ₂ are different, the present invention is not limited to this. The potential changes ΔVad ₁ and ΔVad ₂ may be equal, and K ₁ and K ₂ may be different. Also in this case, K ₁ and K ₂ are preferably different from each other and 1/5 <K ₂ / K ₁ <5. Also, when K ₂ is greater than K _1, 1 <it is preferably K ₂ / K ₁ <5.

In the above description, when the red, green, and blue gradations in the input signal are the same (for example, when an achromatic color is indicated in the input signal), the source signal voltages corresponding to the different colors are substantially equal. The invention is not limited to this. For example, by adjusting white balance, the source signal voltages corresponding to different colors may be different even if the gradations of red, green, and blue in the input signal are equal.

As described above, in the liquid crystal display device 100 of the present embodiment, the voltage difference between the auxiliary capacitors of the sub-pixels of the pixels corresponding to the same color (for example, red) of the different color display pixels D is different. Even in the case of color, the front luminance may change, and the γ characteristic in the front direction may change. In this case, even if the gradation of the same color (for example, red) in the input signal is the same, the writing voltage (source signal voltage) to the pixel of this color corresponding to the different color display pixel D is made different, so that the front direction By adjusting the luminance, the gamma characteristic in the front direction can be adjusted.

Focusing on the red pixels R ₁ and R ₂ of the color display pixels D ₁ and D ₂ shown in FIG. 4, for example, even when the gradations of the same color (for example, red) in the input signal are equal, the red pixels R ₁ and R ₂ In order to adjust the front luminance of the red pixel R ₂ to be substantially equal to each other, the source signal voltages when writing to the red pixels R ₁ and R ₂ may be made different from each other. In this case, the average effective voltage of the sub-pixel R _1a and the sub-pixel R _1b of the red pixel R ₁ is different from the average effective voltage of the sub-pixel R _2a and the sub-pixel R _2b of the red pixel R ₂ .

Further, as described above, the auxiliary capacitors CSa and CSb of the sub-pixels a and b may be different depending on the color display pixel D. However, the luminance in the front direction may change due to the difference between the auxiliary capacitors CSa and CSb.

As described above, when the voltage Vg of the gate signal changes from VgH to VgL, the voltages of the

subpixel electrodes

14a and 14b decrease by Vd. The value of the pull-in voltage Vd is the parasitic capacitance Cgd between the gate electrodes and the drain electrodes of the

TFTs

16a and 16b, and all the capacitances connected to the drains of the

TFTs

16a and 16b (liquid crystal capacitances CLa and CLb, auxiliary capacitances CSa and CSb, and others). The parasitic capacitance). Generally, since Cgd, CLa, CLb and CSa, CSb are the main capacities, the pull-in voltage Vd is expressed as Vd = Cgd × Vg / (CLa + CSa) or Vd = Cgd × Vg / (CLb + CSb). .

In order to realize a desired voltage difference ΔV according to the color display pixel D, if the auxiliary capacitors CSa and CSb are made different as described above, the value of the pull-in voltage Vd also differs depending on the color display pixel D. Become. When the value of the pull-in voltage Vd varies depending on the color display pixel D, the average value (DC level) of the voltage applied to the liquid crystal layer 30 varies, and the counter electrode 24 is common to all the color display pixels D. In the typical configuration provided in FIG. 3, the DC voltage component applied to the liquid crystal layer 30 for all the color display pixels D cannot be sufficiently reduced even when the counter voltage is adjusted, and the display quality and reliability are improved. There may be a problem of lowering. In this case, the luminance in the front direction can be matched by changing the source signal voltage with respect to the gradation level of the input signal by signal processing. Alternatively, reliability can be improved by changing the Cgd of the

TFTs

16a and 16b according to the color display pixel D and optimizing the counter voltage.

As described above, in the liquid crystal display device 100 of the present embodiment, the γ characteristics from the diagonal direction of the pixels can be varied and the γ characteristics from the front can be adjusted. For this reason, even if the vertical scanning period is relatively long, that is, even if the writing frequency is low, it is possible to suppress the deterioration of display quality.

Hereinafter, an example of the liquid crystal display device 100 of this embodiment will be described in detail with reference to FIGS. 9 to 11.

FIG. 9 shows an equivalent circuit of the liquid crystal display device 100 of the present embodiment. In this specification, the gate wirings G in the n-th row, the (n + 1) th row,... May be referred to as gate wirings G _n , G _{n + 1} ,. The auxiliary capacitor CSa of the sub-pixel a of the n-th row pixel corresponds to the CS line CCSa1 or CCSa2, and the auxiliary capacitor CSb of the sub-pixel b of the n-th row pixel corresponds to the CS line CCSb1 or CCSb2. The auxiliary capacitance CSa of the sub-pixel a of the pixel in the (n + 1) th row corresponds to the CS wiring CCSb1 or CCSb2, and the auxiliary capacitance CSb of the sub-pixel b of the pixel in the (n + 1) th row corresponds to the CS wiring CCSc1 or CCSc2. Yes.

Here, in each of the color display pixels D, the capacitance values CCS of the auxiliary capacitors CSa and CSb are substantially equal to each other. For example, approximately equal auxiliary capacitance CSa the color display pixel D _1, the capacitance value CCS ₁ of CSb auxiliary capacitance CSa the color display pixel D _2, the capacitance value CCS ₂ of CSb.

The amplitude of the CS signal supplied to the CS wiring CCSa1 is substantially equal to the amplitude of the CS signal supplied to the CS wiring CCSb1, and the amplitude of the CS signal supplied to the CS wiring CCSa2 is supplied to the CS wiring CCSb2. It is almost equal to the amplitude of the CS signal. Note that the amplitude of the CS signal supplied to the CS wiring CCSa1 is different from the CS signal supplied to the CS wiring CCSa2. However, the phase of the CS signal supplied to the CS wiring CCSa1 may be equal to the phase of the CS signal supplied to the CS wiring CCSa2. Similarly, the amplitude of the CS signal supplied to the CS wiring CCSb1 is different from the CS signal supplied to the CS wiring CCSb2, and the amplitude of the CS signal supplied to the CS wiring CCSc1 is different from the CS signal supplied to the CS wiring CCSc2. .

Here, attention is paid to the red pixel R ₁ of the color display pixel D ₁ . In the sub-pixel R _1a , one electrode of each of the liquid crystal capacitor CLa and the auxiliary capacitor CSa is connected to the drain of the TFT 16 a that functions as a switching element of the sub-pixel a, and the other electrode of the liquid crystal capacitor CLa is connected to the counter electrode 24. The other electrode of the auxiliary capacitor CSa is connected to the CS wiring CCSa1. In the subpixel R _1b , one electrode of each of the liquid crystal capacitor CLb and the auxiliary capacitor CSb is connected to the drain of the TFT 16b that functions as a switching element of the subpixel b, and the other electrode of the liquid crystal capacitor CLb is the counter electrode. 24, and the other electrode of the auxiliary capacitor CSb is connected to the CS wiring CCSb1. The gates of the

TFTs

16a and 16b are both connected to the gate line Gn, and the sources of the

TFTs

16a and 16b are both connected to the source line S. The green pixel G ₁ and the blue pixel B _{1 of} the color display pixel D ₁ have the same configuration as the red pixel R ₁ .

Next, attention is paid to the red pixel R ₂ of the color display pixel D ₂ . In the sub-pixel R _2a , one electrode of each of the liquid crystal capacitor CLa and the auxiliary capacitor CSa is connected to the drain of the TFT 16a functioning as a switching element of the sub-pixel a, and the other electrode of the liquid crystal capacitor CLa is connected to the counter electrode 24. The other electrode of the auxiliary capacitor CSa is connected to the CS wiring CCSa2. In the subpixel R _2b , one electrode of each of the liquid crystal capacitor CLb and the auxiliary capacitor CSb is connected to the drain of the TFT 16b functioning as a switching element of the subpixel b, and the other electrode of the liquid crystal capacitor CLb is the counter electrode. 24, and the other electrode of the auxiliary capacitor CSb is connected to the CS wiring CCSb2. The gates of the

TFTs

16a and 16b are both connected to the gate line Gn, and the sources of the

TFTs

16a and 16b are both connected to the source line S. The green pixel G ₂ and the blue pixel B _{2 of} the color display pixel D ₂ have the same configuration as the red pixel R ₂ .

Although redundant description is omitted to avoid redundancy, the auxiliary capacitance of the sub-pixel a of the pixels R ₃ , G ₃ , and B ₃ of the color display pixel D ₃ corresponds to the CS wiring CCSb 2, and the sub-pixel b The auxiliary capacitance corresponds to the CS wiring CCSc2. Similarly, the auxiliary capacitance of the sub-pixel a of the pixels R ₄ , G ₄ , and B ₄ of the color display pixel D ₄ corresponds to the CS wiring CCSb1, and the auxiliary capacitance of the sub-pixel b corresponds to the CS wiring CCSc1. .

In FIG. 9, different CS signals correspond to different color display pixels D corresponding to the same gate line Gn, but the present invention is not limited to this.

FIG. 10 shows another equivalent circuit of the liquid crystal display device 100. In the liquid crystal display device 100, the auxiliary capacitors CSa and CSb of the sub-pixels a and b have different capacitance values depending on the color display pixel D. For example, the sub-pixel a in the color display pixel D _1, b of the auxiliary capacitance CSa, the electrostatic capacitance value CCS ₁ of CSb, vice pixels a in the color display pixel D _2, b of the auxiliary capacitance CSa, the capacitance value of CSb Different from CCS ₂ . For example, the overlapping area between the auxiliary capacitance electrode and the auxiliary capacitance counter electrode in the sub-pixels a and b of the color display pixel D _{1 is} the difference between the auxiliary capacitance electrode and the auxiliary capacitance counter-electrode in the sub-pixels a and b of the color display pixel D ₂ . It is different from the overlapping area.

Here, the auxiliary capacitance of the sub-pixel a of the color display pixel D adjacent in the row direction corresponds to the same CS signal, and the auxiliary capacitance of the sub-pixel b of the color display pixel D adjacent in the row direction is different. To the same CS signal. For example, the auxiliary capacitance of the sub-pixel a of the color display pixels D ₁ and D ₂ corresponds to the CS signal corresponding to the CS wiring CCSa, and the auxiliary capacitance of the sub-pixel b of the color display pixels D ₁ and D ₂ is the CS wiring. It corresponds to the CS signal corresponding to CCSb.

Here, attention is paid to the red pixel R ₁ of the color display pixel D ₁ . In the sub-pixel R _1a , one electrode of each of the liquid crystal capacitor CLa and the auxiliary capacitor CSa is connected to the drain of the TFT 16 a that functions as a switching element of the sub-pixel a, and the other electrode of the liquid crystal capacitor CLa is connected to the counter electrode 24. The other electrode of the auxiliary capacitor CSa is connected to the CS wiring CCSa. In the subpixel R _1b , one electrode of each of the liquid crystal capacitor CLb and the auxiliary capacitor CSb is connected to the drain of the TFT 16b that functions as a switching element of the subpixel b, and the other electrode of the liquid crystal capacitor CLb is the counter electrode. 24, and the other electrode of the auxiliary capacitor CSb is connected to the CS wiring CCSb. The gates of the

TFTs

16a and 16b are both connected to the gate line Gn, and the sources of the

TFTs

Next, attention is paid to the red pixel R ₂ of the color display pixel D ₂ . In the sub-pixel R _2a , one electrode of each of the liquid crystal capacitor CLa and the auxiliary capacitor CSa is connected to the drain of the TFT 16a functioning as a switching element of the sub-pixel a, and the other electrode of the liquid crystal capacitor CLa is connected to the counter electrode 24. The other electrode of the auxiliary capacitor CSa is connected to the CS wiring CCSa. In the subpixel R _2b , one electrode of each of the liquid crystal capacitor CLb and the auxiliary capacitor CSb is connected to the drain of the TFT 16b functioning as a switching element of the subpixel b, and the other electrode of the liquid crystal capacitor CLb is the counter electrode. 24, and the other electrode of the auxiliary capacitor CSb is connected to the CS wiring CCSb. The gates of the

TFTs

16a and 16b are both connected to the gate line Gn, and the sources of the

TFTs

In the liquid crystal display device 100 shown in FIG. 10, the capacitance value of the auxiliary capacitor CSa of the sub-pixel a of the color display pixel D ₁ is different from the capacitance value of the auxiliary capacitor CSa of the sub-pixel a of the color display pixel D _2. Even if the CS signal corresponding to the auxiliary capacitor CSa of the sub-pixel a of the display pixels D ₁ and D ₂ is the same signal, the effective of the sub-pixel a in the pixels R ₁ , G ₁ and B ₁ of the color display pixel D ₁ The voltage can be made different from the effective voltage of the sub-pixel a in the pixels R ₂ , G ₂ , and B ₂ of the color display pixel D ₂ . Similarly, the capacitance value of the auxiliary capacitance CSb subpixels b of the color display pixels D ₁ is different from the capacitance of the auxiliary capacitor CSb subpixels b of color display pixel D _2, the color display pixel D _1, D ₂ Even if the CS signal corresponding to the auxiliary capacitor CSb of the sub-pixel b is the same signal, the effective voltage of the sub-pixel b in the pixels R ₁ , G ₁ , B ₁ of the color display pixel D ₁ is set to the color display pixel D ₂ . The effective voltage of the sub-pixel b in the pixels R ₂ , G ₂ , and B ₂ can be made different. For this reason, the viewing angle characteristics of the liquid crystal display device 100 are further improved. In this case, the average of the effective voltage and the effective voltage of the sub-pixel b of the sub-pixel a in each of the color pixels R ₁ display pixel D _{_{_1,}} G _1, B ₁ is a color display pixel D ₂ of the pixel R ₂ , G ₂ and B ₂ are approximately equal to the average of the effective voltage of the subpixel a and the effective voltage of the subpixel b.

Although redundant description is omitted to avoid redundancy, the auxiliary capacitance of the sub-pixel a of the pixels R ₃ , G ₃ , and B ₃ of the color display pixel D ₃ corresponds to the CS wiring CCSb, and the auxiliary capacitance of the sub-pixel b The capacitance corresponds to the CS wiring CCSc. Similarly, the auxiliary capacitance of the sub-pixel a of the pixels R ₄ , G ₄ , and B ₄ of the color display pixel D ₄ corresponds to the CS wiring CCSb, and the auxiliary capacitance of the sub-pixel b corresponds to the CS wiring CCSc. . As described above, the auxiliary capacitances of the adjacent sub-pixels among the color display pixels D adjacent in the column direction correspond to the same CS wiring, thereby reducing the number of CS wirings and increasing the aperture ratio. be able to.

In the liquid crystal display device shown in FIG. 10, one CS wiring corresponds to the sub-pixel b of one pixel and the sub-pixel a of the other pixel of two pixels adjacent in the column direction. Is not limited to this.

FIG. 11 shows still another equivalent circuit of the liquid crystal display device 100. The liquid crystal display device 100 shown in FIG. 11 has the same configuration as that of the liquid crystal display device shown in FIG.

Also in the liquid crystal display device 100, the capacitance values of the sub-pixels a and b differ depending on the color display pixel D. For example, the pixels R ₁ of the color display pixel D _{_{_1,}} G _1, B ₁ sub-pixels in a, b of the auxiliary capacitance CSa, the electrostatic capacitance value CCS ₁ of CSb, the pixels R ₂ of the color display pixels D _2, G ₂ , B ₂ is different from the capacitance values CCS ₂ of the auxiliary capacitors CSa and CSb of the sub-pixels a and b. The overlapping area of the auxiliary capacitance electrode and the auxiliary capacitance counter electrode in the sub-pixels a and b of the color display pixel D ₁ is the overlapping area of the auxiliary capacitance electrode and the auxiliary capacitance counter-electrode in the sub pixels a and b of the color display pixel D _2. Is different.

Here, the auxiliary capacitance of the sub-pixel a of the color display pixel D adjacent in the row direction corresponds to the same CS signal, and the auxiliary capacitance of the sub-pixel b of the color display pixel D adjacent in the row direction is different. Supports CS signals. For example, the auxiliary capacitance of the sub-pixel a of the color display pixels D ₁ and D ₂ corresponds to the CS signal corresponding to the CS wiring CCSa, and the auxiliary capacitance of the sub-pixel b of the color display pixels D ₁ and D ₂ is the CS wiring. It corresponds to the CS signal corresponding to CCSb.

TFTs

16a and 16b are both connected to the gate line Gn, and the sources of the

TFTs

Next, attention is paid to the red pixel R ₂ of the color display pixel D ₂ . In the sub-pixel R _2a , one electrode of each of the liquid crystal capacitor CLa and the auxiliary capacitor CSa is connected to the drain of the TFT 16a functioning as a switching element of the sub-pixel a, and the other electrode of the liquid crystal capacitor CLa is connected to the counter electrode 24. The other electrode of the auxiliary capacitor CSa is connected to the CS wiring CCSa1. In the subpixel R _2b , one electrode of each of the liquid crystal capacitor CLb and the auxiliary capacitor CSb is connected to the drain of the TFT 16b functioning as a switching element of the subpixel b, and the other electrode of the liquid crystal capacitor CLb is the counter electrode. 24, and the other electrode of the auxiliary capacitor CSb is connected to the CS wiring CCSb1. The gates of the

TFTs

16a and 16b are both connected to the gate line Gn, and the sources of the

TFTs

Although the redundant description is omitted to avoid redundancy, the auxiliary capacitance of the sub-pixel a of the pixels R ₃ , G ₃ , and B ₃ of the color display pixel D ₃ corresponds to the CS wiring CCSb 2, and the auxiliary capacitance of the sub-pixel b The capacitance corresponds to the CS wiring CCSc2. Similarly, the auxiliary capacitance of the sub-pixel a of the pixels R ₄ , G ₄ , and B ₄ of the color display pixel D ₄ corresponds to the CS wiring CCSb2, and the auxiliary capacitance of the sub-pixel b corresponds to the CS wiring CCSc2. .

In the liquid crystal display device 100 shown in FIG. 11, the capacitance value of the auxiliary capacitor CSa of the sub-pixel a of the color display pixel D ₁ is different from the capacitance value of the auxiliary capacitor CSa of the sub-pixel a of the color display pixel D _2. Even if the CS signal corresponding to the auxiliary capacitor CSa of the sub-pixel a of the display pixels D ₁ and D ₂ is the same signal, the effective of the sub-pixel a in the pixels R ₁ , G ₁ and B ₁ of the color display pixel D ₁ The voltage can be made different from the effective voltage of the sub-pixel a in the pixels R ₂ , G ₂ , and B ₂ of the color display pixel D ₂ . Similarly, the capacitance value of the auxiliary capacitance CSb subpixels b of the color display pixels D ₁ is different from the capacitance of the auxiliary capacitor CSb subpixels b of color display pixel D _2, the color display pixel D _1, D ₂ Even if the CS signal corresponding to the auxiliary capacitor CSb of the sub-pixel b is the same signal, the effective voltage of the sub-pixel b in the pixels R ₁ , G ₁ , B ₁ of the color display pixel D ₁ is set to the color display pixel D ₂ . The effective voltage of the sub-pixel b in the pixels R ₂ , G ₂ , and B ₂ can be made different. For this reason, the viewing angle characteristics of the liquid crystal display device 100 are further improved.

In the above description, the color display pixels D ₁ and D ₄ having the voltage difference ΔV ₁ are arranged obliquely, and the color display pixels D ₂ and D ₃ having the voltage difference ΔV ₂ are arranged obliquely. Is not limited to this. The color display pixels D having different voltage differences between the effective voltages of the sub-pixels a and b may be arbitrarily arranged.

However, the parasitic capacitance corresponding to each source line is preferably substantially constant. For example, as shown in FIG. 12, even if the color display pixels D having the voltage difference ΔV ₁ are arranged in the row direction in a certain row, and the color display pixels D having the voltage difference ΔV ₂ are arranged in the row direction in adjacent rows. Good. In this case, when viewed in the column direction, the color display pixels D having the voltage difference ΔV _{1 and} the color display pixels D having the voltage difference ΔV ₂ are alternately arranged. By arranging the color display pixels D in this way, the parasitic capacitance corresponding to each source line can be made substantially constant, and signal delay due to a specific source line can be suppressed.

In the liquid crystal display device 100 shown in FIG. 12, the parasitic capacitance corresponding to the source line is substantially constant, but the present invention is not limited to this. The capacitance corresponding to each CS wiring may be substantially constant. For example, as shown in FIG. 13, color display pixels D having a voltage difference ΔV ₁ are arranged in a column in a certain column, and color display pixels D having a voltage difference ΔV ₂ are arranged in a column direction in an adjacent column. Also good. In this case, when viewed in the row direction, the color display pixel D having the voltage difference ΔV _{1 and} the color display pixel D having the voltage difference ΔV ₂ are alternately arranged. By arranging the color display pixels D in this way, the parasitic capacitance corresponding to each CS wiring can be made substantially constant, and a signal delay due to a specific CS wiring can be suppressed.

In the liquid crystal display device 100 shown in FIGS. 12 and 13, the capacitance corresponding to the source line or the CS wiring is set to be substantially constant, but the present invention is not limited to this. The capacitance corresponding to each of the source line and the CS wiring may be substantially constant. For example, as shown in FIG. 14, the color display pixels D having the voltage difference ΔV ₁ may be arranged in a checkered pattern, and the color display pixels D having the voltage difference ΔV ₂ may be arranged in a checkered pattern. In this case, when viewed in the row direction, the color display pixel D having the voltage difference ΔV _{1 and} the color display pixel D having the voltage difference ΔV ₂ are alternately arranged, and the color display having the voltage difference ΔV _{1 is} also viewed in the column direction. Pixels D and color display pixels D having a voltage difference ΔV ₂ are alternately arranged. By arranging the color display pixels D in this manner, the parasitic capacitances corresponding to the source line and the CS wiring can be made substantially constant.

In the above description, there are two types of color display pixels D having different voltage differences ΔV between the effective voltages of the sub-pixels a and b, but the present invention is not limited to this. There may be three or more types of color display pixels D having different voltage differences ΔV. For example, three or more color display pixels D having different capacitance values CCS of the auxiliary capacitors CSa and CSb of the sub-pixels a and b may be provided.

In the above description, there are two types of full width of the CS signal (for example, two types of full width of 2.0 V and 4.0 V in the description with reference to FIGS. 7 and 8). There may be three or more types of full widths. Note that the full width of the CS signal is larger than a value that can suppress whitening to some extent even when one type of full width CS signal is used (the full width is 2.0 V in the description with reference to FIGS. 7 and 8 above). It is preferably a value. Of course, two or more types of color display pixels D having different capacitance values CCS of the auxiliary capacitors CSa and CSb of the sub-pixels a and b may be provided, and two or more types of the full width of the CS signal may be provided.

In the above description, the color display pixels D having different voltage differences ΔV are arranged adjacent to any of the row direction, the column direction, and the diagonal direction for each of the color display pixels D. The invention is not limited to this. For a specific color display pixel D, the voltage difference ΔV between the color display pixels D adjacent in any of the row direction, the column direction, and the diagonal direction may be substantially equal. That is, the color display pixels D having different voltage differences ΔV may be arranged apart from each other.

(Embodiment 2)
Hereinafter, a liquid crystal display device according to a second embodiment of the present invention will be described. FIG. 15 shows a schematic diagram of a liquid crystal display device 100A of the present embodiment. The liquid crystal display device 100A of the present embodiment is the same as that described above except that the voltage difference ΔV between the effective voltages of the sub-pixels a and b in the pixels R, G, and B in the same color display pixel D is not constant. The configuration is the same as that of 100, and redundant description is omitted to avoid redundancy.

FIG. 15 shows the voltage difference ΔV between the effective voltage of the sub-pixel a and the effective voltage of the sub-pixel b in the four color display pixels D ₁ to D ₄ and each pixel in the liquid crystal display device 100A of the present embodiment. Here, in the input signal, the colors displayed by the four color display pixels D ₁ to D ₄ are equal to each other, and in each of the color display pixels D ₁ to D ₄ , the red pixel R, the green pixel G, and the blue pixel B are Equal halftones are shown, and the color display pixels D ₁ to D ₄ show achromatic colors.

In the red pixel R ₁ of the color display pixel D ₁ , the voltage difference between the effective voltage of the sub-pixel R _{1a and} the effective voltage of the sub-pixel R _1b is ΔV _R1 . In the green pixel G ₁ , the voltage difference between the effective voltage of the sub-pixel G _{1a and} the effective voltage of the sub-pixel G _1b is ΔV _G1 , and in the blue pixel B ₁ , the effective voltage of the sub-pixel B _1a and the sub-pixel B _1b The voltage difference from the effective voltage is ΔV _B1 . In the liquid crystal display device 100A, the voltage differences ΔV _R1 , ΔV _G1 , ΔV _B1 in the color display pixel D ₁ are not constant.

For example, each pixel of R ₁ in the color display pixel D _1, G ₁ and B ₁ of the auxiliary capacitance CSa, respectively CCS _R a capacitance value of CCS CSb, CCS _G, When referred to as CCS _B, capacitance values CCS _R, CCS _G By making CCS _B different, the voltage differences ΔV _R1 , ΔV _G1 and ΔV _B1 of the effective voltages of the sub-pixels a and b can be made different according to the pixels R ₁ , G ₁ and B ₁ . Specifically, the overlapping area of the auxiliary capacitance electrodes forming the auxiliary capacitances CSa and CSb of the sub-pixels a and b and the auxiliary capacitance counter electrode may be made different according to the pixels R ₁ , G ₁ and B ₁ .

Alternatively, in the color display pixel D ₁ , the amplitude Vad of the auxiliary capacitance signal (CS signal) supplied to the auxiliary capacitance counter electrodes of the auxiliary capacitances CSa and CSb of the sub-pixels a and b of the pixels R ₁ , G ₁ and B ₁ is set. If they are referred to as Vad _R , Vad _G , and Vad _B , respectively, the amplitudes Vad _R , Vad _G , and Vad _B may be made different depending on the pixels R ₁ , G _1, and B ₁ . Thus, the viewing angle in the oblique direction can be further improved by making the voltage difference between the effective voltages of the sub-pixels a and b of the pixels R ₁ , G ₁ and B ₁ in the color display pixel D ₁ different. it can.

Also in the liquid crystal display device 100A, the voltage difference ΔV _R2 between the effective voltage of the sub-pixel R _{2a and} the effective voltage of the sub-pixel R _2b in the red pixel R ₂ of the color display pixel D ₂ is different from ΔV _R1 . Further, the voltage difference ΔV _G2 between the effective voltage of the sub-pixel G _{2a and} the effective voltage of the sub-pixel G _2b in the green pixel G ₂ is different from ΔV _G1 . Similarly, the voltage difference ΔV _B2 between the effective voltage of the sub-pixel B _{2a and} the effective voltage of the sub-pixel B _2b in the blue pixel B ₂ is different from ΔV _B1 . In the liquid crystal display device 100A, the voltage differences ΔV _R2 , ΔV _G2 , and ΔV _B2 are not constant.

For example, the voltage difference ΔV _B1 is preferably smaller than the voltage differences ΔV _R1 and ΔV _G1 . As described in Patent Document 2, the voltage difference ΔV _B1 of the blue pixel B is smaller than the voltage differences ΔV _R1 and ΔV _{G1 of} the red pixel R and the green pixel G, thereby causing a color balance shift due to an oblique viewing angle. Can be suppressed. The voltage difference [Delta] V _R1 may be larger or smaller than the voltage difference [Delta] V _G1. Alternatively, the voltage difference [Delta] V _R1 may be substantially equal to the voltage difference [Delta] V _G1.

Similarly, the voltage difference ΔV _B2 is preferably smaller than the voltage differences ΔV _R2 and ΔV _G2 . The voltage difference [Delta] V _R2 may be larger or smaller than the voltage difference [Delta] V _G2. Alternatively, the voltage difference [Delta] V _R2 may be substantially equal to the voltage difference [Delta] V _G2.

The ratio of the voltage differences ΔV _R1 , ΔV _G1 and ΔV _B1 is preferably substantially equal to the ratio of the voltage differences ΔV _R2 , ΔV _G2 and ΔV _B2 . In this case, it is possible to easily suppress the chromaticity change from the oblique direction in each color display pixel D.

Hereinafter, advantages of the liquid crystal display device 100A compared to the liquid

crystal display devices

800A and 800B of the comparative example will be described.

FIG. 16 is a schematic diagram of four color display pixels in the liquid crystal display device 800A of the comparative example. The liquid crystal display device 800A subpixel a in the color display pixel D ₁ of the, b of the auxiliary capacitance CSa, capacitance CCS of CSb is substantially constant. In the liquid crystal display device 800A, the amplitudes Vad _R , Vad _G , and Vad _B of the CS voltage in the color display pixel D ₁ are not constant. For example, the full widths ΔVad _R and ΔVad _G are 2.0V, and ΔVad _B is 1.6V.

In the liquid crystal display device 800A, the color display pixels D ₂ to D ₄ have the same configuration as the color display pixel D ₁ . The capacitance values CCS of the auxiliary capacitors CSa and CSb of the sub-pixels a and b are almost constant. Further, the amplitude Vad of the CS voltage in each of the color display pixels D ₂ to D ₄ is not constant. For example, in each of the color display pixels D ₂ to D ₄ , the full widths ΔVad _R and ΔVad _G are 2.0V, and the full width ΔVad _B is 1.6V.

Here, the colors displayed by the four color display pixels D ₁ to D _{4 in} the input signal are equal to each other. In each of the color display pixels D ₁ to D ₄ , the red pixel R, the green pixel G, and the blue pixel B exhibit the same intermediate gradation, and the color display pixels D ₁ to D ₄ exhibit an achromatic color.

FIG. 17A shows a change in chromaticity u ′ with respect to a gradation change in the liquid crystal display device 800A, and FIG. 17B shows a change in chromaticity v ′ with respect to a gradation change. FIGS. 17A and 17B show the chromaticities u ′ and v ′ when viewed from the right at 45 ° with respect to the normal direction of the main surface of the liquid crystal display device 800A. Here, the liquid crystal display device 800A is in the 4DRTN mode.

FIGS. 17A and 17B show the results of changing the full width ΔVad _{B of the} CS signal to 1.4V, 1.6V, and 2.0V, respectively. As described above, ΔVad _R and ΔVad _G are 2.0V, and the ratio (X) of the total width ΔVad _B (1.4V, 1.6V and 2.0V) to ΔVad _R and ΔVad _G (2.0V) is , 0.7, 0.8, and 1.0, respectively.

When the total width ΔVad _B is substantially equal to the total widths ΔVad _R and ΔVad _G (that is, when X = 1.0), in particular, the chromaticity v ′ near the gradation 120 becomes larger than the other gradations, and the achromatic color. Despite being displayed, it appears to shift to yellow. When the amplitude Vad _B is decreased, the chromaticities u ′ and v ′ are decreased near the gradation 120, thereby suppressing the shift to yellow. From FIG. 17A and FIG. 17B, when the full widths ΔVad _R and ΔVad _G are 2.0V, and the full width ΔVad _{B is set} to 1.6V, each variation of chromaticity u ′ and v ′ is suppressed. It is understood that it can be done.

FIG. 18 is a schematic diagram of four color display pixels in the liquid crystal display device 800B of the comparative example. The liquid crystal display device 800B subpixel a in the color display pixel D ₁ of the, b of the auxiliary capacitance CSa, capacitance CCS of CSb is substantially constant. In the liquid crystal display device 800B, the amplitudes Vad _R , Vad _G , and Vad _B in the color display pixel D ₁ are not constant. For example, the full widths ΔVad _R and ΔVad _G are 4.0V, and the full width ΔVad _B is 3.2V.

In the liquid crystal display device 800B, the color display pixels D ₂ to D ₄ have the same configuration as the color display pixel D ₁ . In each of the color display pixels D ₂ to D ₄ , the capacitance values CCS of the auxiliary capacitors CSa and CSb of the sub-pixels a and b are substantially constant. Further, the amplitude Vad of the CS voltage in each of the color display pixels D ₂ to D ₄ is not constant. For example, in each of the color display pixels D ₂ to D ₄ , ΔVad _R and ΔVad _G are 4.0V, and ΔVad _B is 3.2V.

FIG. 19A shows a change in chromaticity u ′ with respect to a gradation change in the liquid crystal display device 800B, and FIG. 19B shows a change in chromaticity v ′ with respect to a gradation change. FIGS. 19A and 19B show chromaticities u ′ and v ′ when viewed from the right at 45 ° with respect to the normal direction of the main surface of the liquid crystal display device 800B. Here, the liquid crystal display device 800B is in the 4DRTN mode.

Here, the result of changing the full width ΔVad _B to 2.8V, 3.2V and 4.0V is shown. As described above, ΔVad _R and ΔVad _G are 4.0V, and the ratio (X) of ΔVad _B (2.8V, 3.2V and 4.0V) to ΔVad _R and ΔVad _G (4.0V). Are 0.7, 0.8, and 1.0, respectively.

When the full width ΔVad _B is equal to the full widths ΔVad _R and ΔVad _G (that is, when X = 1.0), in particular, the chromaticities u ′ and v ′ near the gradation 160 are larger than those of the other gradations. The color appears to shift despite the display of an achromatic color. When the total width ΔVad _B is reduced, the chromaticities u ′ and v ′ decrease in the vicinity of the gradation 160, thereby suppressing the shift to yellow. From FIGS. 19A and 19B, it is understood that when the full widths ΔVad _R and ΔVad _G are 4.0 V, changes in chromaticity u ′ and v ′ can be suppressed when ΔVad _B is 3.2 V. Is done.

FIG. 20 shows the amplitude of the CS signal corresponding to the four color display pixels and the auxiliary capacitance of each pixel in the liquid crystal display device 100A of the present embodiment. Subpixel a in the color display pixel D ₁ of the liquid crystal display device 100A, b of the auxiliary capacitance CSa, capacitance CCS of CSb is substantially constant.

In the liquid crystal display device 100A, the amplitudes Vad _R1 , Vad _G1 , and Vad _B1 of the CS voltage in the color display pixel D ₁ are not constant. For example, ΔVad _R1 and ΔVad _G1 are 2.0V and ΔVad _B1 is 1.6V, as in the liquid crystal display device 800A of the comparative example described above with reference to FIGS.

In the liquid crystal display device 100A, the amplitudes Vad _R2 , Vad _G2 , and Vad _B2 are not constant. For example, ΔVad _R2 and ΔVad _G2 are 4.0 V and ΔVad _B2 is 3.2 V, as in the liquid crystal display device 800B of the comparative example described above with reference to FIGS.

Note that it is substantially the same, respectively, in the liquid crystal display device 100A each pixel R in the color display pixel D ₃ and D _4, G, B is also a color display pixel D ₁ and D _2. The capacitance values CCS of the auxiliary capacitors CSa and CSb of the sub-pixels a and b are almost constant. Further, the amplitude Vad of the CS voltage in each of the color display pixels D ₃ and D ₄ is not constant. For example, ΔVad _R3 and ΔVad _G3 are 2.0V, ΔVad _B3 is 1.6V, ΔVad _R4 and ΔVad _G4 are 4.0V, and ΔVad _B4 is 3.2V. If the ratio of Vad _B to the amplitudes Vad _R and Vad _G of the CS signal in the same color display pixel D is X, X = 0.80.

FIG. 21A shows a change in chromaticity u ′ with respect to a gradation change in the liquid crystal display device 100A, and FIG. 21B shows a change in chromaticity v ′ with respect to a gradation change. FIGS. 21A and 21B show chromaticities u ′ and v ′ when viewed from the right at 45 ° with respect to the normal direction of the main surface of the liquid crystal display device 100A.

Here, for reference, changes in chromaticity u ′ and v ′ in the liquid crystal display device 800 of the comparative example described with reference to FIG. 5 are also shown. In the liquid crystal display device 800 of the comparative example, in each color display pixel D, the capacitance values CCS of the auxiliary capacitors CSa and CSb of the sub-pixels a and b are substantially constant, and the amplitudes Vad _R , Vad _G , Vad _B is constant.

For reference, changes in chromaticity u ′ and v ′ of the liquid crystal display device 100 of Embodiment 1 in which the amplitude Vad _B is equal to the amplitudes Vad _R and Vad _G in each of the color display pixels D are also shown. . In the liquid crystal display device 100 of the first embodiment, in each of the color display pixels D, the capacitance values CCS of the auxiliary capacitors CSa and CSb of the sub-pixels a and b are substantially constant. Although the amplitudes Vad _R , Vad _G , and Vad _B of the CS signal are different depending on the color display pixel D, the amplitudes Vad _R , Vad _G , and Vad _B of the CS signal in the same color display pixel D are constant.

In the liquid crystal display device 100A, the amplitude Vad _B is smaller than the amplitudes Vad _R and Vad _G in each color display pixel D, whereby the voltage difference ΔV _B is changed from the voltage differences ΔV _R and ΔV _G in each color display pixel D. Therefore, yellow shift can be improved. Note that the preferable ratio X varies depending on the liquid crystal capacitors CLa and CLb and the auxiliary capacitors CSa and CSb of the sub-pixels a and b, and may be set as appropriate.

Here, the capacitance values of the auxiliary capacitors CSa and CSb are substantially equal in each color display pixel D, and the amplitudes Vad _R , Vad _G , and Vad of the CS signals of the pixels R, G, and B in the color display pixel D are used. _{Although B} was changed, the present invention is not limited to this. For example, the amplitude Vad _R , Vad _G , Vad _B of the CS signal is made substantially equal in each color display pixel D, and the capacitance values CCS _R of the auxiliary capacitors CSa, CSb of the pixels R, G, B of the color display pixel D are set. , CCS _G and CCS _B may be different.

FIG. 22 shows the ratio of the capacitance values of the four color display pixels and the auxiliary capacitance of each pixel in the liquid crystal display device 100A of the present embodiment. Here, the amplitude of the CS voltage in each of the color display pixels D is substantially constant.

In the liquid crystal display device 100A, the capacitance values CCS _R1 , CCS _G1 , and CCS _B1 of the auxiliary capacitors CSa and CSb of the color display pixel D in the color display pixel D ₁ are not constant, Accordingly, K _R1 , K _G1 , and K _B1 are not constant. For example, K _R1 , K _G1 , and K _B1 are 1.0, 1.0, and 0.8, respectively.

The capacitance values CCS _R2 , CCS _G2 , and CCS _B2 of the auxiliary capacitors CSa and CSb of the pixels R, G, and B of the color display pixel D ₂ in the color display pixel D ₂ are the capacitance values CCS _R1 , CCS _G1 , and CCS _B1 , respectively. Accordingly, K _R2 , K _G2 and K _B2 are different from K _R1 , K _G1 and K _B1 . Note that the capacitance values CCS _R2 , CCS _G2 , and CCS _B2 are not constant, and accordingly, K _R2 , K _G2 , and K _B2 are not constant. For example, K _R2 , K _G2 , and K _B2 are 2.0, 2.0, and 1.6, respectively.

The pixels R, G, and B in the color display pixels D ₃ and D ₄ are substantially the same as the color display pixels D ₁ and D ₂ , respectively. For example, the ratio of K _R3 and K _G3 is 1.0, K _B3 is 0.8, K _R4 and K _G4 are 2.0, and K _B4 is 1.6. Again, K _R of the same color display pixel D, when the ratio of K _B and X for K _G, which is X = 0.80. Thus, the viewing angle characteristics can be further improved by making the capacitance values CCS _R , CCS _G , and CCS _B of the auxiliary capacitors CSa and CSb in the color display pixel D different. Of course, both the amplitudes Vad _R , Vad _G , Vad _B and the capacitance values of the auxiliary capacitors CSa, CSb may be changed in accordance with the color display pixel D.

Incidentally, in the above description, in each color display pixel D, the voltage difference [Delta] V _B red pixel R of the blue pixel B, the voltage difference [Delta] V _R of the green pixel G, has been different from the [Delta] V _G, the present invention is limited to Not. The voltage difference ΔV of another pixel may be different from the voltage difference ΔV of another pixel.

Further, in the above description, the red pixel R in each color display pixel D, the voltage difference [Delta] V _R of the green pixel G, and [Delta] V _G was equal to one another, the present invention is not limited thereto. Red pixel R, the voltage difference [Delta] V _R of the green pixel G, [Delta] V _G may be different.

In the above description, the areas of the sub-pixels a and b in the same pixel are almost equal, but the present invention is not limited to this. The areas of the sub-pixels a and b in the same pixel may be different.

In the above description, one pixel has two sub-pixels that can have different luminances, but the present invention is not limited to this. One pixel may have three or more subpixels that can have different luminances.

In the above description, the color display pixel has three pixels of a red pixel, a green pixel, and a blue pixel, but the present invention is not limited to this. The color display pixel may have four or more pixels. For example, the color display pixel may have a yellow pixel in addition to a red pixel, a green pixel, and a blue pixel. Alternatively, the color display pixel may include a yellow pixel and a cyan pixel in addition to a red pixel, a green pixel, and a blue pixel.

According to the embodiment of the present invention, the display quality in the oblique direction of the liquid crystal display device can be improved.

DESCRIPTION OF SYMBOLS 10 Back substrate 14 Pixel electrode 20 Front substrate 24 Counter electrode 30 Liquid crystal layer 100 Liquid crystal display device

Claims

A liquid crystal display device comprising a plurality of color display pixels including a first color display pixel and a second color display pixel,
Each of the plurality of color display pixels has a plurality of pixels including a first pixel, a second pixel, and a third pixel;
Each of the plurality of pixels has a first subpixel and a second subpixel,
In each of the plurality of pixels of each of the plurality of color display pixels, each of the first subpixel and the second subpixel is:
A liquid crystal capacitor formed by a counter electrode, a liquid crystal layer, and a sub-pixel electrode facing the counter electrode through the liquid crystal layer;
And an auxiliary capacitance formed by an auxiliary capacitance electrode electrically connected to the subpixel electrode, an insulating layer, and an auxiliary capacitance counter electrode facing the auxiliary capacitance electrode via the insulating layer. ,
In the case where each of the first pixel of the first color display pixel and the first pixel of the second color display pixel performs display with at least some intermediate gradation, the first pixel of the first color display pixel in the first pixel The voltage difference between the effective voltage of the first subpixel and the effective voltage of the second subpixel is the effective voltage of the first subpixel and the effective voltage of the second subpixel in the first pixel of the second color display pixel. A liquid crystal display device that differs from the voltage difference from the voltage.
2. In each of the plurality of pixels of the plurality of color display pixels, a capacitance value of the auxiliary capacitance of the first subpixel is substantially equal to a capacitance value of the auxiliary capacitance of the second subpixel. A liquid crystal display device according to 1.
In each of the plurality of pixels of the plurality of color display pixels, the amplitude of the auxiliary capacitance signal supplied to the auxiliary capacitance counter electrode corresponding to the first subpixel is an auxiliary capacitance corresponding to the second subpixel. The liquid crystal display device according to claim 1, wherein the liquid crystal display device has substantially the same amplitude as the auxiliary capacitance signal supplied to the counter electrode.
In the case where each of the first pixel of the first color display pixel and the first pixel of the second color display pixel performs display with at least some intermediate gradation, the first pixel of the first color display pixel in the first pixel Write voltages to the subpixel electrodes corresponding to the first subpixel and the second subpixel are subpixels corresponding to the first subpixel and the second subpixel in the first pixel of the second color display pixel. The liquid crystal display device according to claim 1, wherein the liquid crystal display device is different from a writing voltage to the electrode.
The amplitude of the auxiliary capacitance signal supplied to the auxiliary capacitance counter electrode corresponding to the first subpixel and the second subpixel in the first pixel of the first color display pixel is the second color display pixel. 5. The liquid crystal display device according to claim 1, wherein an amplitude of an auxiliary capacitance signal supplied to an auxiliary capacitance counter electrode corresponding to the first subpixel and the second subpixel in one pixel is different.
The capacitance values of the auxiliary capacitances of the first subpixel and the second subpixel in the first pixel of the first color display pixel are the first subpixel and the subpixel in the first pixel of the second color display pixel. The liquid crystal display device according to claim 5, wherein the liquid crystal display device is substantially equal to the capacitance value of the auxiliary capacitance of the second subpixel.
The capacitance values of the auxiliary capacitances of the first subpixel and the second subpixel in the first pixel of the first color display pixel are the first subpixel and the subpixel in the first pixel of the second color display pixel. The liquid crystal display device according to claim 1, wherein the liquid crystal display device is different from a capacitance value of an auxiliary capacitor of the second subpixel.
The amplitude of the auxiliary capacitance signal supplied to the auxiliary capacitance counter electrode corresponding to the first subpixel and the second subpixel in the first pixel of the first color display pixel is the second color display pixel. The liquid crystal display device according to claim 7, wherein an amplitude of an auxiliary capacitance signal supplied to an auxiliary capacitance counter electrode corresponding to the first subpixel and the second subpixel in one pixel is substantially equal.
The capacitance values of the auxiliary capacitances of the first subpixel and the second subpixel in the first pixel of the first color display pixel are the first subpixel and the subpixel in the first pixel of the second color display pixel. Unlike the capacitance value of the auxiliary capacitance of the second subpixel,
The amplitude of the auxiliary capacitance signal supplied to the auxiliary capacitance counter electrode corresponding to the first subpixel and the second subpixel in the first pixel of the first color display pixel is the second color display pixel. 5. The liquid crystal display device according to claim 1, wherein an amplitude of an auxiliary capacitance signal supplied to an auxiliary capacitance counter electrode corresponding to the first subpixel and the second subpixel in one pixel is different.
When each of the plurality of pixels of the first color display pixel performs display at the at least some intermediate gradation, the effective voltage of the first sub-pixel in each of the plurality of pixels of the first color display pixel and the The liquid crystal display device according to claim 1, wherein a voltage difference with an effective voltage of the second subpixel is substantially equal to each other.
When each of the plurality of pixels of the first color display pixel performs display at the at least certain intermediate gradation, the first subpixel and the second subpixel in each of the plurality of pixels of the first color display pixel. The liquid crystal display device according to claim 10, wherein averages of effective voltages of the pixels are substantially equal to each other.
The auxiliary capacitance signals supplied to the auxiliary capacitance counter electrodes corresponding to the first subpixel and the second subpixel in each of the plurality of pixels of the first color display pixel have substantially the same amplitude. The liquid crystal display device according to any one of 11.
The liquid crystal display device according to claim 1, wherein capacitance values of auxiliary capacitances of the first subpixel and the second subpixel in each of the plurality of pixels of the first color display pixel are substantially equal to each other. .
When each of the first pixel and the third pixel of the first color display pixel performs display at the intermediate gray level, the effective of the first sub-pixel in the first pixel of the first color display pixel. The voltage difference between the voltage and the effective voltage of the second subpixel is the voltage difference between the effective voltage of the first subpixel and the effective voltage of the second subpixel in the third pixel of the first color display pixel. The liquid crystal display device according to claim 1, which are different from each other.
The amplitude of the auxiliary capacitance signal supplied to the auxiliary capacitance counter electrode corresponding to the first subpixel and the second subpixel in the first pixel of the first color display pixel is the first color display pixel of the first color display pixel. The liquid crystal display device according to claim 1, wherein an amplitude of an auxiliary capacitance signal supplied to an auxiliary capacitance counter electrode corresponding to the first subpixel and the second subpixel in three pixels is different. .
The capacitance values of the auxiliary capacitances of the first subpixel and the second subpixel in the first pixel of the first color display pixel are the first subpixel and the subpixel of the third pixel of the first color display pixel. The liquid crystal display device according to claim 1, wherein the liquid crystal display device is different from a capacitance value of an auxiliary capacitor of the second subpixel.
The liquid crystal display device according to claim 1, wherein the first pixel, the second pixel, and the third pixel are a red pixel, a green pixel, and a blue pixel, respectively.
The plurality of color display pixels are arranged in a matrix of a plurality of rows and a plurality of columns,
The liquid crystal display device according to claim 1, wherein the second color display pixel is adjacent to the first color display pixel in a row direction or a column direction.