JP3260084B2 - Color liquid crystal display - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color liquid crystal display, and more particularly to a so-called backlight type liquid crystal display.

[0002]

2. Description of the Related Art In a so-called backlight type color liquid crystal display device, a backlight unit is disposed on the back of a liquid crystal display panel having a pair of transparent substrates disposed as an envelope with a liquid crystal layer interposed therebetween. It is configured.

The liquid crystal display panel has a display portion in which a large number of pixels capable of independently controlling the degree of light transmission are arranged in a matrix on the surface of the liquid crystal layer on the liquid crystal layer side. The display unit is configured so that light emitted from the backlight unit can be incident on the display unit.

[0004]

However, one of the advantages of the color liquid crystal display device constructed as described above is low power consumption. In particular, there is a demand for compatibility of color uniformity.

Therefore, the inventors of the present application have found that when the liquid crystal display panel is observed from a wide viewing direction, that is, an angle greatly deviated from the normal direction to the liquid crystal display panel, the color of the display surface is changed. Focusing on the fact that the backlight unit will change, we have studied how to achieve both low power consumption of the backlight unit and high image quality, especially uniform color.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a color liquid crystal display device which achieves both a reduction in power consumption and an improvement in image quality, in particular, color uniformity.

[0007]

SUMMARY OF THE INVENTION Among the inventions disclosed in the present application, the outline of a representative one will be briefly described.
It is as follows.

Means 1. In a color liquid crystal display device including at least a liquid crystal display panel having color filters corresponding to the three primary colors and a backlight unit disposed on the back of the liquid crystal display panel, a viewing angle range in which a color shift is equal to or less than an allowable level is obtained. When the luminance of light emitted from the backlight unit has any observation direction in which a half-width angle indicating an angle at which the luminance is halved with respect to the front luminance is small, and the viewing angle range is displayed at the maximum luminance. Color C.I. I. E. FIG. The absolute value of the deviation from the value in the normal direction of the liquid crystal display panel at the 1931 xy chromaticity coordinates is 0.0314 or less for the red primary color and y for the green primary color.
The coordinate is 0.0273 or less, and the x-coordinate is 0.1 in the blue primary color.
The angle range is set to 0177 or less.

Means 2. In a color liquid crystal display device including at least a liquid crystal display panel having color filters corresponding to three primary colors and a backlight unit disposed on the back of the liquid crystal display panel, light emitted from the backlight unit to the liquid crystal display panel The direction in which the luminance of the liquid crystal display panel is 50% of the luminance measured in the normal direction of the liquid crystal display panel is represented by an angle measured with respect to the normal, and this is defined as a half-luminance angle. For the green, blue primary colors, and white point, the chromaticity shift when observed from the normal direction is represented by C.I. I. E. FIG. 1931 Coordinate values based on xy chromaticity coordinates, (xr, yr), (xg, yg), (xb, y
b), (xw, yw), and the chromaticity shift when the red, green, and blue primary colors displayed on the liquid crystal display panel are observed from an arbitrary direction shifted by a certain angle from the normal direction is represented by C.I. I. E. FIG. 1
931 xy The chromaticity coordinate is represented by a coordinate value. The chromaticity coordinate value is shifted with respect to the red primary color by the x coordinate shift Δx.
The deviation of the r and y coordinates is assumed to be Δyr, and for the green primary color, x
When the coordinate shift is Δxg, the y coordinate shift is Δyg, and for the blue primary color, the x coordinate shift is Δxb, and the y coordinate shift is Δyb,

[0010]

(Equation 1)

[0011]

(Equation 2)

[0012]

(Equation 3)

When the range of the viewing angle from the normal direction that satisfies the above condition is defined as the same-color viewing angle range, the same-color viewing angle range> luminance half-value angle is satisfied.

Means 3. In a color liquid crystal display device including at least a liquid crystal display panel provided with color filters corresponding to three primary colors, and a backlight unit disposed on the back of the liquid crystal display panel, the liquid crystal display panel includes:
A display electrode and a reference electrode are provided in each pixel region on the liquid crystal side of the substrate disposed in contact with the liquid crystal layer, and an electric field substantially parallel to the substrate is generated in the liquid crystal layer by a voltage applied to these electrodes. The display electrode modulates the light transmitted through the liquid crystal layer, wherein the display electrode is a video signal from a video signal line via a switching element that is turned on by the supply of a scan signal from the scan signal line. Is supplied, and the reference electrode is configured to supply a reference signal from a reference signal line, and measures the luminance of light emitted from the backlight unit to the liquid crystal display panel in the normal direction of the liquid crystal display panel. The direction at which 50% of the obtained luminance is obtained is represented by an angle measured with respect to the normal, and this is defined as a luminance half-value angle,
For each primary color displayed on the liquid crystal display panel, the chromaticity deviation when observed from an arbitrary direction deviated from the normal direction by a certain angle with respect to the chromaticity when observed from the normal direction is represented by C.I. I. E. FIG. 1931 xy chromaticity coordinates, and the chromaticity coordinate value shift is 0.0314 for the red primary color, 0.0273 for the green primary color, and 0.0273 for the green primary color. When the range of the observation angle from the normal direction in which the deviation of the x coordinate does not exceed 0.0177 for the blue primary color is defined as the same-color viewing angle range, the same-color viewing angle range> luminance half-value angle is satisfied. It is assumed that.

In the color liquid crystal display device thus configured, when the liquid crystal display panel is observed from an angle deviated from the normal direction, a change in the color of the display surface from the backlight unit to an allowable angle range. The angle of light emission is limited.

In this case, the angle range in which the color change of the display surface is permissible when observed from an angle shifted from the normal direction of the liquid crystal display panel is a characteristic of the liquid crystal display panel itself. Is defined as the same color viewing angle range, and the half-width angle of light emission from the backlight unit in at least one observation direction is set smaller than this angle range.

This eliminates the need to radiate unnecessary light from the backlight unit, thereby reducing power consumption.

Further, in the angle range in which light is emitted from the backlight unit, the color becomes uniform, so that high image quality can be realized at the same time.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG . FIG. 1 is a side view showing one embodiment of the liquid crystal display device according to the present invention.

In FIG. 1, first, the liquid crystal display panel 10
There is 0. The liquid crystal display panel 100 includes, as an envelope, a pair of transparent substrates disposed with a liquid crystal layer interposed therebetween, and forms a display unit on the surface on the liquid crystal layer side. In this display section, a large number of pixels capable of independently controlling the degree of light transmission are arranged in a matrix in the liquid crystal layer.

Further, each pixel is provided with a color filter corresponding to one of the three primary colors.

The liquid crystal display panel 100 is of a so-called horizontal electric field type, which can recognize a clear image even when observed from a large viewing angle with respect to the normal of the display surface, and has a so-called wide angle visual field. It is known as excellent. The detailed configuration of the liquid crystal display panel 100 will be described later.

On the back of the liquid crystal display panel 100, a backlight unit 103 is arranged. The backlight unit 103 of the present embodiment includes the cold cathode ray tube 1
03B, a reflection plate 103C, and a light guide plate 103A, and a diffusion plate 102, a corrugated sheet 101 on the light guide plate 103A.
Are sequentially laminated.

With such a configuration, the light from the cold cathode ray tube 103B is guided into the light guide plate 103A, and is diffused from the surface facing the liquid crystal display panel 100 to the diffuser plate 10A.
2. Radiated through the corrugated sheet 101 and transmitted through the liquid crystal display panel 100.

In the color display by the liquid crystal display panel, even if the same color is displayed in the same place, a color difference occurs depending on the angle at which the same is viewed. On the other hand, even if two display colors should be displayed in the same color, it is actually acceptable if there is a color difference of a certain amount or less between these display colors.

Therefore, by defining an allowable color difference for a certain color, a viewing angle range in which substantially the same display color can be obtained for that color is determined. The herein this range of viewing angles, indicated by theta ₂ called the same color viewing angle range.

The display colors in this specification are evaluated not only by the primary color filters provided in the liquid crystal display panel but also by the effects of the spectral characteristics of the cold cathode ray tube and the like of the backlight.

In the backlight unit 103,
Can be determined angle theta ₁ which shows a half-value width of the emitted light amount. In this embodiment, in particular, the half-width θ ₁ of the backlight unit 103 is configured to be smaller than the same-color observation angle range θ _{2 of the} liquid crystal display panel 100.

Here, the angle θ ₁ indicating the half-value width of the light emitted from the backlight unit 103 is defined as a value indicating the angle at which the luminance of the light emitted from the backlight unit 103 is reduced by half with respect to the front luminance. I do.

First, the difference between the display colors is most noticeable visually when the respective colors of red, green, and blue are displayed (ie, display 3) in a state where the maximum luminance is given.
It has been confirmed that the color shift is (primary color). For this reason, the degree of color misregistration due to a change in the viewing angle direction when each of the red, green, and blue colors is displayed at the maximum luminance (display of three primary colors) can be used as a guide for judging color uniformity.

FIG. 2 shows a so-called C.I. I. E. FIG. 1931 shows a 1931 chromaticity diagram, in which chromaticity coordinates in a display that gives the maximum luminance of each of red, green, blue, and white in the normal direction of the liquid crystal display panel 100, that is, three primary colors for display and The chromaticity coordinates of the white point are represented by R ′,
G ', B', and W 'are shown. And R ',
An area surrounded by a triangle connecting points indicating G ′ and B ′
The range of colors that can be reproduced by the liquid crystal display device in the normal direction of the liquid crystal display panel.

In the color liquid crystal display device, the coordinates of the three primary colors R ', G', and B 'fluctuate depending on the direction of the visual angle. The range of colors will be reduced. For example, as shown in FIG. 2, when the color changes to R ″, G ″, and B ″, the range of colors that the liquid crystal display device can reproduce in the viewing angle direction is within a region surrounded by a triangle connecting them. At this time, the colors of R ′, G ′, and B ′ cannot be reproduced, and the range of colors that can be displayed is significantly reduced.

From this, it can be seen that the evaluation of the degree of variation in the viewing angle direction of R ', G', B 'toward W' can correspond to the evaluation of the color uniformity range of the color liquid crystal display device. .

FIG. 3 corresponds to FIG. 2 and shows three primary colors R ′,
The X and Y coordinates of G ′, B ′ and white are shown. In the table, Δx and Δy are the x and y coordinates of R ′, G ′ and B ′, and the x and y coordinates of W ′. And the absolute value of the difference from. Therefore, R ', G', B 'and W'
Can be represented by √ (Δx ² + Δy ² ).

As apparent from FIG. 2, R ',
When the G 'and B' colors are shifted in the W 'direction, the range of reproducible colors is significantly reduced, so that R' and G '
Are changes in the x coordinate and the y coordinate, that is, Δx, Δ
With y, the degree of variation of each color of red, green, and blue is red,
R ', G',
It can be evaluated based on the amount of deviation from B ′ to W ′.

There is no unified rule for judging the amount of color shift due to a change in the viewing angle direction of the liquid crystal display panel. This is because its quantitative definition is difficult. However, regarding the variation of the luminance for each gradation depending on the viewing angle direction, the measurement method is a non-inverted viewing angle measurement method using EIAJED-
2522 (method for measuring a matrix-type liquid crystal display module). Here, regardless of the actual number of displayable gradations of the liquid crystal display module, the non-inverted viewing angle is the angle range in which the magnitude relationship of the luminance of each gradation when all the gradations are divided into eight is not reversed.

Therefore, in this embodiment, the color shift is determined as follows.

First, the reference of colors in the liquid crystal display panel is three primary colors of red, green and blue. Therefore, this 3
The color shift was determined. This is because all the display colors are realized by the combination of these three colors, and therefore, by judging the color shift of these three colors, substantially all the color shifts are determined.

Next, when judging a color shift, the level at which the luminance is maximized for the display primary colors and the level at which the luminance is minimal for the other two primary colors are set. That is,
Each color of red, green, and blue was determined as a color shift when displayed at a level giving the maximum luminance. Because
It is practically effective to determine the color shift under this condition in that the color shift at this time is most noticeable visually and the color shift at this time leads to a decrease in the color reproduction range. Because.

The chromaticity coordinates (xr, yr), (xg, yr) of R ', G', B 'in the normal direction of each color of red, green, and blue under the above conditions.
yg), (xb, yb) and the chromaticity coordinates (xw, yw) of the color (ie, white) W ′ at the level that gives the minimum luminance of each color are respectively

[0041]

(Equation 4)

[0042]

(Equation 5)

[0043]

(Equation 6)

Can be shown. Then, the distance is divided into eight for each color in accordance with the method for measuring the non-inverted viewing angle described above. At this time, in the present embodiment, simply dividing into eight equal parts,
The value equally divided was set as the allowable deviation amount ΔC. If the color shift of each of the three primary colors due to a change in the visual direction is equal to or less than this amount, it is determined that the colors are uniform. This determination method is referred to as “criterion 1”.

The results of experimentally examining the viewing angle characteristics of the color of the liquid crystal display panel 100 applied in the present embodiment based on such settings will be described with reference to FIGS. 3, 4, 5, and 6. FIG.

FIG. 3 shows the x and y coordinates of each of W ', R', G ', and B', and the permissible shift amount ΔC of each of the red, green, and blue colors as the criterion 1 in FIG.

In place of the permissible color shift amount based on the criterion 1, the range of reproducible colors is remarkably reduced when R 'is shifted in the x direction and G' is shifted in the y direction. Change only in x coordinate, G 'is change only in y coordinate, B' is x, y
Although the coordinates have the same effect, it is also possible to determine a color change by providing an allowable value for a change in the x-coordinate in order to determine strictly. Therefore, this determination method is used as a criterion 2 in FIG.
It was shown to.

The same color viewing angle range θ ₂ of the liquid crystal display panel 100 is determined by the C.I. I.
E. FIG. The absolute value of the displacement of the 1931 xy chromaticity coordinate with respect to the value in the normal direction of the liquid crystal display panel is as follows.
3 or less, the value is set as a value in an angle range where the x coordinate is 0.0177 or less in blue.

FIGS. 4 to 6 show the color uniform ranges of red, green, and blue based on ΔC based on the criterion 2.

FIG. 4 shows viewing angle characteristics in red display, FIG. 5 shows viewing angle characteristics in green display, and FIG. 6 shows viewing angle characteristics in blue display. Here, θ and φ representing the viewing angles used in the respective figures are defined as angles in the circumferential direction with respect to the liquid crystal display panel surface and angles with respect to the normal direction, respectively, as shown in FIG.

As shown in FIGS. 4, 5 and 6, respectively,
Red, green, and blue colors are displayed, and φ is 4 in almost all azimuthal directions.
It is clear that color shift does not occur up to a range exceeding 0 °. This means that, in the liquid crystal display panel of this embodiment, the same color viewing angle range θ ₂ is 80 ° (40 ° × 2). In addition, it turns out that the vertical direction is 100 ° or more (50 ° × 2 or more).

Next, the configuration of one embodiment of the so-called in-plane switching mode liquid crystal display panel 100 applied to this embodiment will be described below.

First, the outline of a so-called in-plane switching type liquid crystal display substrate to which the present invention is applied will be described.

As shown in FIG. 13, the liquid crystal display panel 10
And one of the transparent substrates 1A among the transparent substrates arranged to face each other via the liquid crystal of the liquid crystal display panel 100.
The scanning signal line 2 and the reference signal line 4 which extend in the x direction (row direction) and are juxtaposed in the y direction (column direction) are formed on the surface on the liquid crystal side.

In this case, the reference signal line 4, the scanning signal line 2 relatively separated from the reference signal line 4 from above the transparent substrate 1A, and the reference signal close to the scanning signal line 2 are shown in FIG. .., The scanning signal lines 2 relatively spaced apart from the reference signal line 4, and so on.

A video signal line 3 which is insulated from the scanning signal line 2 and the reference signal line 4 and extends in the y direction and is arranged in the x direction is formed.

Here, a rectangular area having a relatively large area surrounded by each of the scanning signal line 2, the reference signal line 4, and the video signal line 3 is an area formed as a unit pixel. Are arranged in a matrix to form a display surface. The detailed configuration of each unit pixel will be described later.

The liquid crystal display panel 100 is provided with a vertical scanning circuit 5 and a video signal driving circuit 6 as external circuits, and the vertical scanning circuit 5 sequentially supplies a scanning signal (voltage) to each of the scanning signal lines 2. The video signal drive circuit 6 supplies a video signal (voltage) to the video signal line 3 in accordance with the timing.

The vertical scanning circuit 5 and the video signal driving circuit 6 are supplied with power from a liquid crystal driving power supply circuit 7 and transmit image information from the CPU 8 to the controller 9.
Thus, the display data and the control signal are divided and input.

The voltage applied to the reference signal line 4 is also supplied from the liquid crystal drive power supply circuit 7.

Hereinafter, an embodiment of each unit pixel in the liquid crystal display panel 100 thus configured will be described.

FIG. 8 is a plan view showing one embodiment of the unit pixel in the liquid crystal display device 100. FIG. In the following description, a coordinate system is used in which the z direction is the normal direction of the substrate, the x direction is the horizontal direction, and the y direction is the vertical direction. 9 is a cross-sectional view taken along line IX-IX of FIG. 8, FIG. 10 is a cross-sectional view taken along line XX, and FIG. 11 is a cross-sectional view taken along line XI-XI.

Referring to FIG. 8, a reference signal line 4 extending in the x direction and a scanning signal line 2 separated from and parallel to reference signal line 4 are formed on the main surface of transparent substrate 1A (see FIG. 13). ing.

Here, three reference electrodes 14 are integrally formed on the reference signal line 4. That is, two of the reference electrodes 14 are in the y-direction side of a pixel region formed by a pair of video signal lines 3 described later, that is, in the (-) y direction in proximity to the respective video signal lines 3. It is formed to extend to the vicinity of the scanning signal line 2, and the other one is formed between them.

On the surface of the transparent substrate 1A on which the scanning signal lines 2, the reference signal lines 4, and the reference electrodes 14 are formed, the insulating film 15 made of, for example, a silicon nitride film covers the scanning signal lines 2 and the like. (See FIGS. 9, 10, and 11). The insulating film 15 is used for the scanning signal line 2 and the reference signal line 4 for a video signal line 3 described later.
As a gate insulating film for a region where the thin film transistor TFT is formed, and as a dielectric film for a region where the storage capacitor Cstg is formed.

First, the semiconductor layer 16 is formed on the surface of the insulating film 15 in the region where the thin film transistor TFT is formed.
Are formed. The semiconductor layer 16 is made of, for example, amorphous Si, and is formed on the scanning signal line 2 via the insulator layer 15 so as to overlap a portion close to the video signal line 3. Thus, a part of the scanning signal line 2 also serves as a gate electrode of the thin film transistor TFT.

Then, on the surface of the insulating film 15 thus formed, as shown in FIG. 8, the video signal lines 3 extending in the y direction and juxtaposed in the x direction are formed. .

The video signal line 3 is integrally provided with a drain electrode 3A extending to a part of the surface of the semiconductor layer 16 of the thin film transistor TFT.

Further, a display electrode 18 is formed on the surface of the insulating film 15 in the pixel region. This display electrode 1
Reference numeral 8 is formed so as to run between the reference electrodes 14. That is, one end of the display electrode 18 also serves as the source electrode 18A of the thin film transistor TFT, extends in the (+) y direction as it is, further extends in the x direction along the reference signal line 4, and then (-) y It has a U-shape extending in the direction and having the other end.

In this case, the portion of the display electrode 18 that overlaps with the reference signal line 4 constitutes a storage capacitor Cstg made of the insulating film 15 as a dielectric film between the display electrode 18 and the reference signal line 4. The storage capacitor Cstg has an effect of storing video information on the display electrode 18 for a long time when the thin film transistor TFT is turned off, for example.

The surface of the semiconductor layer 16 at the interface with the drain electrode 3A and the source electrode 18A of the thin-film transistor TFT is doped with phosphorus (P) to form a high concentration layer. Ohmic contact is planned. In this case, the semiconductor layer 16
The high-concentration layer is formed on the entire surface of the surface, and after forming each of the electrodes, the high-concentration layer other than the electrode formation region is etched using the electrodes as a mask to have the above-described configuration. Can be.

Then, as described above, the thin film transistor TF
T, video signal line 3, display electrode 18, and storage capacitor Cs
A protective film 19 (see FIGS. 9, 10 and 11) made of, for example, a silicon nitride film is formed on the upper surface of the insulating film 15 on which the tg is formed, and an alignment film 20 is formed on the upper surface of the protective film 19.
Are formed to constitute the lower substrate of the liquid crystal display panel 100. Note that a polarizing plate 21 is disposed on a surface of the lower substrate opposite to the liquid crystal layer side.

As shown in FIG. 9, a light-shielding film 22 is formed on a portion of the transparent substrate 1B serving as the upper substrate on the liquid crystal side, at a portion corresponding to a boundary portion of each pixel region. The light shielding film 22 has a function of preventing the thin film transistor TFT from being directly irradiated with light and a function of improving display contrast. The light-shielding film 22 is formed in a region shown by a broken line in FIG. 8, and an opening formed in the region constitutes a substantial pixel region.

Further, a color filter 23 for obtaining the three primary colors of display is formed by covering the opening of the light-shielding film 22. The color filter 23 has different color characteristics from those in the adjacent pixel region and also has a light-shielding property. It has a boundary on the film 22. Further, a flat film 24 made of a resin film or the like is formed on the surface on which the color filter 23 is formed as described above.
On the surface of No. 4, an alignment film 25 is formed. A polarizing plate 26 is disposed on the surface of the upper substrate opposite to the liquid crystal layer.

Here, the relationship between the alignment film 20 formed on the transparent substrate 1A side and the polarizing plate 21 and the alignment film 25 formed on the transparent substrate 1B side and the polarizing plate 26 will be described with reference to FIG.

The orientation films 20 and 2 correspond to the direction 207 of the electric field applied between the display electrode 18 and the reference electrode 14.
5, the angle of the rubbing direction 208 is φLC. The angle of the polarization axis 209 of one of the polarizing plates 21 is φP. The polarization axis of the other polarizing plate 26 is φ
It is orthogonal to P. Further, φLC = φP.
The liquid crystal layer LC has a positive dielectric anisotropy Δε of 7.3 (1 kHz) and a refractive index anisotropy Δn of 0.0.
A 73 (589 nm, 20 ° C.) nematic liquid crystal composition is used.

The alignment films 20 and 25 having such a relationship
The structure of the polarizers 21 and 26 and the like is what is called a normally black mode. By generating an electric field E parallel to the transparent substrate 1A in the liquid crystal layer LC, light is transmitted to the liquid crystal layer LC. It is supposed to. However, in this embodiment, the present invention is not limited to such a normally black mode, and it goes without saying that a normally white mode in which light transmitted through the liquid crystal layer LC when no electric field is applied may be the maximum. Absent.

The liquid crystal display panel constructed in the normally black mode in this way is known to be able to achieve a so-called contrast ratio of about 140.

Here, the structure of the backlight unit of this embodiment will be described in detail with reference to an exploded perspective view of FIG.

In this embodiment, a corrugated sheet having a prism-shaped outer surface on the liquid crystal display panel side was used as the corrugated sheet 101 in the backlight. In this embodiment, the vertex angle θ ₄ of the prism portion is 100 °.

The corrugated sheet 101 is arranged such that the vertices of the prism extending linearly extend parallel to the left and right sides of the panel.

Light can be collected by using a corrugated sheet having a prism-shaped outer surface on the liquid crystal display panel side as used in this embodiment. That is, the fact that the half width can be reduced is disclosed in Japanese Patent Application Laid-Open No. 4-67016 and the like, and is a technique currently used in most of backlight units for liquid crystal display panels for portable use.

Thus, in this embodiment, the light in the left-right direction of the light emitted from the backlight unit can be condensed, and the half-width θ ₁ can be reduced to 70 ° or less. In this embodiment, the in-plane switching mode liquid crystal display device used as the liquid crystal display panel 100 has the same color viewing angle range of 80 as described above.
° or more, the half width θ ₁ of the emitted light of the backlight unit can be made smaller than the same color viewing angle range θ ₂ at least in the left-right direction of the liquid crystal display panel.

According to the color liquid crystal display device of the embodiment described above, when the liquid crystal display panel 100 is observed from an angle shifted from the normal direction, the backlight unit 103 is set within a range where the color of the display surface does not change. This limits the angle of light emission from the light source.

In this case, the viewing angle range in which the color of the display surface does not change when observed from an angle shifted from the normal direction of the liquid crystal display panel 100 is a characteristic of the liquid crystal display panel 100 itself. The range is defined as the same color viewing angle range, and the backlight unit 1
The angle of light emission from the light emitting element 03 is set small.

Thus, the backlight unit 10
Since there is no need to emit unnecessary light from 3,
The power consumption can be reduced.

In this embodiment, the corrugated sheet 101 is
Although the vertices of the prism extending linearly are arranged so as to extend in parallel with the left and right sides of the panel, it goes without saying that the same effect can be obtained if they are arranged in other directions.

The backlight unit 103 used in this embodiment has a configuration in which the light guide plate 103A has a wedge shape and a cold cathode ray tube 103B is arranged on the widened end face, as shown in FIG. In the case where the light guide plate 103A has a flat plate shape and the cold cathode ray tubes 103 are arranged on one or a plurality of end faces thereof, or when a plurality of cold cathode ray tubes are arranged immediately below the diffusion plate 102 as shown in FIG. It goes without saying that it is included. Needless to say, other linear or planar light sources may be used instead of the cold cathode ray tubes.

Further, in this embodiment, the liquid crystal display panel 10
A horizontal electric field type liquid crystal display panel which is already known to obtain a wide viewing angle characteristic was used as 0, but in at least one direction (horizontal and vertical directions) and at least one of the three primary colors, It goes without saying that all liquid crystal display panels having a configuration satisfying θ ₂ > θ ₁ between the angles θ ₁ and θ ₂ are included in the category of the present embodiment.

Embodiment 2 FIG . FIG. 21 is a schematic diagram of the present embodiment. The difference between this embodiment and the first embodiment is that a diffusion plate 102B having the same properties as the diffusion plate 102 is newly provided between the liquid crystal display panel 100 and the corrugated sheet 101 shown in the first embodiment.

As a result, a corrugated sheet was obtained in Example 1
When the same sheet is used, the half width is 70% in Example 1.
Spread to 80 ° for °. In this case, the liquid crystal display panel 100 of the first embodiment satisfies the theta _2> theta ₁ because it has the same color viewing angle theta ₂ of 80 ° or more in all directions, it is possible to achieve the same effects as in Example 1.

Further, in this embodiment, the newly provided diffusion sheet makes the spectral characteristics of the light incident on the liquid crystal display panel smooth, so that the visual luminance fluctuation becomes smooth,
In addition to the effects of the first embodiment, visually natural display can be realized.

Embodiment 3 FIG . FIG. 22 shows a schematic diagram of this embodiment. The difference between this embodiment and the first embodiment is that two corrugated sheets 101 shown in the first embodiment are provided. Each of the two corrugated sheets was disposed such that the extending directions of the linearly extending vertices of the respective prisms were orthogonal to each other.

In this case, the light in the vertical direction can be collected together with the light in the horizontal direction of the liquid crystal display panel, and the power consumption can be further reduced as compared with the first embodiment. .

Embodiment 4 FIG . The schematic diagram of this embodiment is the same as FIG. In the present embodiment, the vertex angle θ ₄ of the corrugated sheet of the third embodiment was set to 90 °. Thus, the half-width theta ₁ can be 60 ° or less, it was possible to further improve the front luminance.

Embodiment 5 FIG . In this embodiment, among the corrugated sheets of the third embodiment, the corrugated sheet for condensing light in the left-right direction has a vertical angle of 100 °, and the corrugated sheet for condensing light in the vertical direction has a vertex angle of 90 °. The light collection rate of the light in the vertical direction
The light collection rate of the light in the left-right direction was improved.

Since the liquid crystal display device is mainly used on a desk, the viewing angle required in the vertical direction is smaller than the viewing angle required in the horizontal direction. Therefore, by improving the light-collecting rate in the vertical direction from the light-collecting rate in the left-right direction, low power consumption can be realized without impairing the practical image quality. In the present embodiment, it is possible to further reduce the power consumption while achieving the same image quality as that of the third embodiment.

Embodiment 6 FIG . In this embodiment, the liquid crystal display device shown in the first embodiment is particularly configured as a notebook PC. FIG. 14 is an external view showing a configuration of a liquid crystal display device of a notebook PC. The liquid crystal display device 200 of a notebook PC usually has a liquid crystal display panel 201 and a keyboard 202 integrally attached thereto. For this reason, the size of the liquid crystal display panel is almost limited to a diagonal length of 14 inches. The operator observes the liquid crystal display panel at a distance of about 30 cm or more from the liquid crystal display panel.

In this case, as long as the operator observes the liquid crystal display panel from the front, the operator can always recognize the normal display of colors in the entire area of the panel surface.

That is, as shown in FIG. 15, when observing the liquid crystal display panel 201, there is a difference in the viewing angle between the center and the periphery of the panel. Here, in the figure, when the distance from the observer's eye to the center of the panel is d, the maximum visual angle difference is θ ₃ . It goes without saying that this maximum difference in viewing angle varies depending on the distance from the observer's eye to the center of the panel.

On the other hand, FIG. 16 is a graph showing the result of calculating the relationship between the distance from the observer's eye to the panel and the viewing angle difference for each size of the liquid crystal display panel.

Therefore, in the configuration of the sixth embodiment,
It is clear that the maximum value of the viewing angle difference is about 30 °.

Therefore, the same color viewing angle range θ ₂ of the liquid crystal display panel used in this embodiment is larger than twice (30 ° × 2) the maximum value of the viewing angle difference.
As long as the operator observes the liquid crystal display panel from the front, the operator can always recognize the normal display of colors in the entire area of the panel.

It goes without saying that the liquid crystal display device having such a configuration can exert a great effect by being used in a field dealing with color itself, for example, in the fields of the printing industry and the clothing industry.

Embodiment 7 FIG . In this embodiment, the liquid crystal display device shown in the first embodiment is configured as a desk monitor. FIG. 17 is a diagram showing a configuration of a liquid crystal display device 300 as a desk monitor. In the liquid crystal display device 300 as a desk monitor, a keyboard is usually attached separately, so that the size of the liquid crystal display panel is up to 18 inches, and the operator of the keyboard is required to operate the liquid crystal display panel with respect to the liquid crystal display panel. Therefore, the liquid crystal display panel is observed at a distance of about 40 cm or more.

The liquid crystal display device 300 thus configured
It has been found that the same color viewing angle range θ ₂ of the liquid crystal display panel is 80 °, and as apparent from FIG. 16, when the liquid crystal display panel is smaller than the 18-inch size, As long as the liquid crystal display panel is observed from the front, normal display of colors can always be recognized in the entire area of the panel surface.

As in the case of the sixth embodiment, a great effect can be exerted by using in a field dealing with color itself, for example, a field of the printing industry, a clothing industry and the like.

Embodiment 8 FIG . In this embodiment, the liquid crystal display device shown in the first embodiment is directly configured as a desk monitor. As apparent from FIG. 16, even if the liquid crystal display panel reaches a size of 26 inches, as long as the operator observes the liquid crystal display panel from the front, a normal display of colors is always displayed over the entire area of the panel surface. Be able to recognize.

Embodiment 9 FIG . In this embodiment, in the liquid crystal display device shown in the first embodiment, in particular, a 6-bit driver is incorporated in the video signal driving circuit 6 (see FIG. 13).
The display is capable of displaying 60,000 multicolors.

Such multi-color display can be achieved with the premise of a liquid crystal display device capable of expanding a fixed color region, and has a great effect as a liquid crystal display device for multimedia. What you get.

Embodiment 10 FIG . FIG. 23 shows a diagram corresponding to FIG. 18 in the first embodiment. In the present embodiment, the corrugated sheet 101
The point is that a sheet having a sinusoidal outer surface is used instead of the corrugated sheet having the prismatic outer surface of the first embodiment.

[0112] Even when a sheet having a corrugated shape is used, the same effect as when a sheet having a prism-shaped outermost surface is used can be obtained, for example, as described in US Pat. No. 5,394,255. Etc.

As a result, the luminance change of the light radiated from the backlight within the angle range of θ ₁ becomes more continuous than in the case of the first embodiment, and it is possible to improve the sense of visual in-plane uniformity of luminance. it can.

Further, in the present embodiment, since the sheet having a sinusoidal shape itself has the same effect as the diffusion plate, even if the scattering plate 102B shown in FIG. 2, and the scattering plate 102B becomes unnecessary, so that light absorption by the sheet can be eliminated.

[0115]

As is apparent from the above description,
According to the color liquid crystal display device of the present invention, a device with low power consumption can be obtained.

[Brief description of the drawings]

FIG. 1 is a side view showing an embodiment of a color liquid crystal display device according to the present invention.

FIG. 2 shows a color liquid crystal display device according to the present invention. I.
E. FIG. It is a figure demonstrated on a 1931 xy chromaticity diagram.

FIG. 3 is an explanatory diagram showing chromaticity coordinates of three primary colors of white, red, green and blue of the color liquid crystal display device according to the present invention.

FIG. 4 is an explanatory diagram showing a color (red) uniform region in a liquid crystal display panel of a color liquid crystal display device according to the present invention.

FIG. 5 is an explanatory diagram showing a color (green) uniform region in a liquid crystal display panel of a color liquid crystal display device according to the present invention.

FIG. 6 is an explanatory diagram showing a color (blue) uniform region in a liquid crystal display panel of a color liquid crystal display device according to the present invention.

FIG. 7 is a diagram for explaining the definition of the viewing angle shown in FIGS. 4 to 6;

FIG. 8 is a plan view showing a configuration of one embodiment of a liquid crystal display panel applied to a color liquid crystal display device according to the present invention.

9 is a sectional view taken along line IX-IX in FIG.

FIG. 10 is a sectional view taken along line XX of FIG. 8;

11 is a sectional view taken along line XI-XI in FIG.

FIG. 12 is a plan view showing one embodiment of a relationship between an alignment direction and a polarization axis formed on a liquid crystal display panel applied to a color liquid crystal display device according to the present invention.

FIG. 13 is a configuration diagram showing one embodiment of a liquid crystal display panel and a driving circuit thereof in a color liquid crystal display device according to the present invention.

FIG. 14 is an external view showing another embodiment of the color liquid crystal display device according to the present invention.

FIG. 15 is a diagram for explaining effects of the liquid crystal display device shown in FIG.

16 is a diagram for describing an effect of the liquid crystal display device shown in FIG.

FIG. 17 is an external view showing another embodiment of the color liquid crystal display device according to the present invention.

FIG. 18 is an exploded perspective view showing another embodiment of the color liquid crystal display device according to the present invention.

FIG. 19 is a sectional view showing another embodiment of the color liquid crystal display device according to the present invention.

FIG. 20 is a sectional view showing another embodiment of the color liquid crystal display device according to the present invention.

FIG. 21 is an exploded perspective view showing another embodiment of the color liquid crystal display device according to the present invention.

FIG. 22 is an exploded perspective view showing another embodiment of the color liquid crystal display device according to the present invention.

FIG. 23 is an exploded perspective view showing another embodiment of the color liquid crystal display device according to the present invention.

[Explanation of symbols]

100: liquid crystal display panel, 103: backlight unit, θ _1: half width indicating the angle at which the luminance of light emitted from the backlight unit is halved from the front luminance, θ _2: liquid crystal display panel Constant tone angle range.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kazuhiro Ogawa 3300 Hayano Mobara-shi, Chiba Pref.Electronic Device Division (72) Inventor Keiichiro Ashizawa 3300 Hayano Mobara-shi Chiba Pref. Within the Device Division (72) Inventor Kiyohe Kinukawa 3300 Hayano, Mobara-shi, Chiba Pref. Electronic Device Division, Hitachi, Ltd. (56) References JP-A-6-59255 (JP, A) JP-A-6-194648 (JP) , A) JP-A-7-77690 (JP, A) JP-A-5-33129 (JP, U) JP-A-7-29532 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB Name) G02F 1/1335

Claims (17)

(57) [Claims] 1. A color filter corresponding to three primary colors is provided.
A liquid crystal display device comprising at least a liquid crystal display panel and a backlight unit disposed on the back of the liquid crystal display panel, wherein the liquid crystal display panel includes a diffusion plate from the backlight unit.
The emitted light is transmitted and emitted from the backlight unit to the liquid crystal display panel
The luminance of light is 5 times the luminance measured in the normal direction of the liquid crystal display panel.
The direction of 0% is represented by the angle measured with respect to the normal, and
This is defined as a luminance half-value angle, and each primary color displayed on the liquid crystal display panel is observed from an arbitrary direction shifted from the normal direction by a certain angle corresponding to the chromaticity when observed from the normal direction. The chromaticity deviation caused by C.I. I. E. FIG. It is represented by coordinate values based on 1931 xy chromaticity coordinates, and the deviation of each chromaticity coordinate is 0.0314 in x coordinate for the red primary color and 0.0314 for the green primary color
0.0273 in y-coordinate and x-coordinate for blue primary color
Observation angle from the normal direction not exceeding 0.0177
If the range is defined as the same color viewing angle range, the same color viewing angle range
Is a wide viewing angle characteristic exceeding 40 °, and the same color viewing angle range
A color liquid crystal display device characterized by satisfying the half-luminance angle . 2. A color filter corresponding to three primary colors is provided.
A liquid crystal display device comprising at least a liquid crystal display panel, and a backlight unit disposed on the back of the liquid crystal display panel, wherein the liquid crystal display panel includes a diffusion plate from the backlight unit.
The emitted light is transmitted and emitted from the backlight unit to the liquid crystal display panel
The luminance of light is 5 times the luminance measured in the normal direction of the liquid crystal display panel.
The direction of 0% is represented by the angle measured with respect to the normal, and
This is defined as the luminance half-value angle, and the red, green, blue primary colors and white color displayed on the LCD panel
For the point, the chromaticity when observed from the normal direction is
C. I. E. FIG. 1931 xy chromaticity coordinates,
(Xr, yr), (xg, yg), (xb, yb),
(Xw, yw) and, red, which is displayed on the liquid crystal display panel, green, normal line how the blue primary color
Color when viewed from any direction deviated from the direction by a certain angle
Degree of the degree is C. I. E. FIG. 1931 by xy chromaticity coordinates
The deviation of the chromaticity coordinate value is represented by the coordinate value. For the red primary color, the deviation of the x coordinate is Δxr, and the deviation of the y coordinate is
This is Δyr, and for the green primary color, the deviation of the x coordinate is Δ
The deviation of the xg and y coordinates is Δyg, and for the blue primary color,
Assuming that the deviation of the x coordinate is Δxb and the deviation of the y coordinate is Δyb
, (Equation 2) (Equation 3) Viewing the range of the viewing angle from the normal direction that satisfies
When defined as an angle range, the same color viewing angle range exceeds 40 °.
Wide viewing angle characteristics, and the same color viewing angle range> the luminance
A color liquid crystal display device satisfying a half-value angle . 3. A color filter corresponding to three primary colors is provided.
A liquid crystal display device comprising at least a liquid crystal display panel, and a backlight unit disposed on the back of the liquid crystal display panel, wherein the liquid crystal display panel includes a diffusion plate from the backlight unit.
The transmitted light is transmitted, and the liquid crystal display panel is
A display electrode and a reference electrode are provided in each pixel area on the crystal side surface.
And the voltage applied to these electrodes causes
An electric field substantially parallel to the substrate is generated,
Modulates light transmitted through the liquid crystal layer,
The display electrode is turned off by the supply of the scanning signal from the scanning signal line.
From the video signal line via the switching element
An image signal is supplied and the reference electrode
A reference signal is supplied from the power line, and emitted from the backlight unit to the liquid crystal display panel
The luminance of light is 5 times the luminance measured in the normal direction of the liquid crystal display panel.
The direction of 0% is represented by the angle measured with respect to the normal, and
Les defined as half-luminance angle, for each primary color to be displayed on the liquid crystal display panel, for the chromaticity of when observed from the normal direction, when viewed from any direction shifted an angle from the normal line direction Of the chromaticity of C.I. I. E. FIG. Expressed in the coordinate value by 1931 xy chromaticity coordinates, the deviation of the chromaticity coordinate values, the deviation of the x-coordinate for the red primary is 0.0314, the deviation of the y-coordinate for the green primary color 0.0273, For the blue primary color, the normal direction in which the deviation of the x coordinate does not exceed 0.0177
If the range of viewing angles from different directions is defined as the same color viewing angle range
If, color liquid crystal display device characterized by satisfying the same color viewing angle> the half-luminance angle. 4. The liquid crystal display panel has a panel diagonal size.
Is 26 inches or less and the same color viewing angle range is 40
° or more.
Color liquid crystal display device. 5. A liquid crystal display panel and a backlight unit
Between, a corrugated sheet with light condensing properties is interposed
The color liquid crystal display device according to claim 1, wherein: 6. Between a liquid crystal display panel and a backlight.
The outermost surface where the interposed corrugated sheet is placed on the panel side
It is a corrugated sheet having a prism shape and
The apex angle of the rhythmic shaped part is 100 ° or less.
The color liquid crystal display device according to claim 1, wherein 7. Between a liquid crystal display panel and a backlight
Interposed corrugated sheet, left and right of color LCD
Wave-shaped sheet for collecting light in the vertical direction and light for the vertical direction
Waves that have a corrugated sheet that converges light in the horizontal direction
The wave shape system that condenses light in the vertical direction from the light condensing rate of the mold sheet
The color liquid crystal display device according to claim 1, wherein the light collection rate of the sheet is higher . 8. A liquid crystal display panel, according to claim 2, characterized in that the panel diagonal size is set to at least 40 ° the same color viewing angle range in the panel entire circumferential direction below 26 inches
A color liquid crystal display device as described in the above. 9. The color liquid crystal display device according to claim 2 , wherein a corrugated sheet having a light condensing property is interposed between the liquid crystal display panel and the backlight unit. 10. The corrugated sheet interposed between the liquid crystal display panel and the backlight is a corrugated sheet having a prism-shaped outermost surface disposed on the panel side, and
3. The color liquid crystal display device according to claim 2, wherein the apex angle of the prism-shaped portion is 100 [deg.] Or less. 11. A corrugated sheet interposed between a liquid crystal display panel and a backlight, a corrugated sheet for condensing light in a horizontal direction of a color liquid crystal display device, and a corrugated sheet for condensing light in a vertical direction. 3. The light-collecting rate of the corrugated sheet for condensing light in the vertical direction is higher than that of the corrugated sheet for condensing light in the left-right direction.
A color liquid crystal display device as described in the above. 12. Between a liquid crystal display panel and a corrugated sheet,
3. The color liquid crystal display device according to claim 2 , wherein a sheet having a light diffusing property is arranged . 13. A liquid crystal display panel having a panel diagonal size of 26 inches or less and a viewing angle range of the same color of 4 on the entire periphery of the panel.
4. The color liquid crystal display device according to claim 3 , wherein the angle is set to 0 [deg.] Or more. 14. The color liquid crystal display device according to claim 3 , wherein a corrugated sheet having a light condensing property is interposed between the liquid crystal display panel and the backlight unit. 15. The corrugated sheet interposed between the liquid crystal display panel and the backlight is a corrugated sheet having a prism-shaped outermost surface disposed on the panel side, and
4. The color liquid crystal display device according to claim 3, wherein the apex angle of the prism-shaped portion is 100 [deg.] Or less. 16. A corrugated sheet interposed between the liquid crystal display panel and the backlight, a corrugated sheet for condensing light in the left-right direction of the color liquid crystal display device, and a corrugated sheet for condensing light in the up-down direction. claim a seat, and from the light collection efficiency of the lateral direction of the light corrugated sheet for focusing, and wherein the higher towards the light collection efficiency of the corrugated sheet for condensing the vertical light 3
A color liquid crystal display device as described in the above. 17. Between a liquid crystal display panel and a corrugated sheet,
The color liquid crystal display device according to claim 3 , wherein a sheet having a light diffusing property is arranged.