JPH11295717A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to improve the brightness of a liquid crystal display device and to control a color temperature of white color independently of three primary colors. SOLUTION: Relating to a liquid crystal display device holding a liquid crystal composition between a pair of substrates, having color filters different in color phase for displaying in color on one of the substrate pair, and having switching elements for selecting picture elements on the other substrate, a picture element composing on dot for the above color display is constituted of the unit picture elements 1R, 1G, 1B, and 1W. And, the color filters R, G, B corresponding to the three primary colors corresponding to the areas of the three of these four unit picture elements on the above other substrate are arranged on the above-mentioned one substrate, and a color filter W corresponding to white is arranged in the area corresponding to another unit picture element 1W.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device capable of improving white luminance and controlling a color temperature independently of a color tone of three primary colors.

[0002]

2. Description of the Related Art A liquid crystal display device has been widely used as a display device capable of high-definition and color display for a notebook computer or a display monitor.

[0003] Conventional liquid crystal display devices include a simple matrix type using a liquid crystal panel in which a liquid crystal layer is sandwiched between a pair of substrates having parallel electrodes formed so as to intersect each other on each inner surface, and one of a pair of substrates. An active matrix type liquid crystal display device using a liquid crystal panel having a switching element for selecting a pixel unit is known.

An active matrix type liquid crystal display device is
A so-called vertical electric field type liquid crystal display device (generally, a TN type active matrix type) using a liquid crystal panel in which an electrode group for pixel selection is formed on a pair of upper and lower substrates as represented by a twisted nematic (TN) type. A liquid crystal panel in which an electrode group for pixel selection is formed only on one of a pair of upper and lower substrates,
There is a so-called in-plane switching mode liquid crystal display device (generally referred to as an IPS mode liquid crystal display device).

In the liquid crystal panel constituting the former TN mode active matrix type liquid crystal display device, the liquid crystal is twisted by 90 ° in a pair (two) of substrates, and is absorbed on the outer surfaces of the upper and lower substrates of the liquid crystal panel. Two polarizing plates are laminated with the axial direction arranged in crossed Nicols and the absorption axis on the incident side made parallel or perpendicular to the rubbing direction.

In such a TN type active matrix type liquid crystal display device, when no voltage is applied, the incident light becomes linearly polarized light on the incident side polarizing plate, and this linearly polarized light propagates along the twist of the liquid crystal layer, and the outgoing side polarized light. When the transmission axis of the plate coincides with the azimuthal angle of the linearly polarized light, all the linearly polarized light is emitted and white display is performed (a so-called normally open mode).

When a voltage is applied, the direction (director) of a unit vector indicating the average alignment direction of the liquid crystal molecular axes constituting the liquid crystal layer is oriented in a direction perpendicular to the substrate surface, and the azimuth of the incident side linearly polarized light. Since the angle does not change, it coincides with the absorption axis of the exit-side polarizing plate, so that black display is performed. (See "Basics and Applications of Liquid Crystals" published by the Industrial Research Council in 1991).

On the other hand, an electrode group for pixel selection and an electrode wiring group are formed only on one of a pair of substrates, and a voltage is applied between adjacent electrodes (between a pixel electrode and a counter electrode) on the substrate by applying a voltage. In an IPS type liquid crystal display device in which layers are switched in a direction parallel to the substrate surface, a polarizing plate is arranged so as to display black when no voltage is applied (a so-called normally closed mode).

The liquid crystal layer of this IPS mode liquid crystal display device is
In the initial state, the director of the liquid crystal layer is in a homogeneous orientation parallel to the substrate surface, and in a plane parallel to the substrate, the director of the liquid crystal layer is parallel or somewhat angled with the electrode wiring direction when no voltage is applied, and the liquid crystal layer is oriented when the voltage is applied. The direction of the director shifts in a direction perpendicular to the electrode wiring direction with the application of the voltage, and the director direction of the liquid crystal layer is 45 times smaller than the director direction when no voltage is applied.
° When tilted in the electrode wiring direction, the liquid crystal layer at the time of applying the voltage has an azimuth of 90 degrees of polarization as if it were a half-wave plate.
And the azimuth of the polarized light coincides with the transmission axis of the exit-side polarizing plate, and a white display is obtained.

This IPS mode liquid crystal display device has a feature that a change in hue and contrast is small even at a viewing angle and a wide viewing angle is achieved (Japanese Patent Laid-Open No. 5-505).
247).

In the above-mentioned full-color liquid crystal display devices, a color filter system is mainly used. In this method, a pixel corresponding to one dot of color display is divided into three, and a color filter corresponding to each of three primary colors, for example, red (R), green (G), and blue (B) is arranged in each unit pixel. This is achieved by doing so.

FIG. 23 is a plan view schematically showing each unit pixel area constituting one pixel of the conventional liquid crystal display device and the function of a reproduced color possessed by each unit pixel. FIG. FIG. 1B is a plan view showing the arrangement of a plurality of pixels.

In FIG. 23, 1 indicates one pixel, 1R indicates a red unit pixel, 1G indicates a green unit pixel, and 1B indicates a blue unit pixel.

A conventional one pixel 1 is a red unit pixel 1R,
It is composed of a green unit pixel 1G and a blue unit pixel 1B. Each unit pixel has a function of reproducing the primary color and a function of reproducing multiple colors at a rate of transmitted light of three unit pixels.

FIG. 24 is a schematic block diagram illustrating a circuit for generating red (R), green (G), and blue (B) gradation data applied to each unit pixel in a conventional liquid crystal display device.
The circuit for generating the grayscale data includes red (R), green (G), and blue (B) signals input from a video signal source such as a host computer.
Is supplied to the video signal drive circuit 404 via the controller 401 constituting the liquid crystal display device, and the video signal drive circuit 404 generates a video signal of each unit pixel as a drive signal for driving each unit pixel. It is supplied to the signal electrode.

[0016]

However, in the above-mentioned conventional liquid crystal display device, there is a problem that the luminance of white cannot be increased. That is, if the area of one pixel is 1,
The area of the unit pixel corresponding to each primary color is equal to 1/3
become. Further, for example, in a color filter formed in a pixel corresponding to red, it is ideal that all light corresponding to blue and green is absorbed and 100% of light corresponding to red is transmitted. There is only about 3 transmittance.

Therefore, the luminance of white in the conventional liquid crystal display device is 1 × (1 × () for each unit pixel when one light enters each pixel, even if the loss due to the polarizing plate and other factors are ignored. 1/3) × (2/3) = 2/9. Since white is reproduced by combining the wavelengths of light transmitted through the three primary colors of red, green and blue, this is the white value of one pixel.

As described above, the low light use efficiency caused by the color filter system itself is an obstacle to the improvement of the brightness of the liquid crystal display device, and the power consumption and the light brightness of the liquid crystal display device are further reduced. It is a problem to be solved to achieve.

In addition to this, control of white color temperature and 3
There is a problem that it is difficult to achieve color reproducibility of primary colors.
In the color filter system, white is reproduced by combining light transmitted through the three primary colors. For this reason, the white color temperature depends on the colors of the three primary color filters. However, since the color of each color filter is also used to reproduce each primary color, it cannot be unilaterally determined only from the color temperature of white.

For example, if the color temperature of white is to be raised, that is, if the color is to be moved in a bluish direction, the color of the red color filter may be lightened. However, this causes the red color reproducibility to deteriorate. As described above, the color filter method has an essential problem that it is difficult to achieve both control of the white color temperature and color reproducibility of the three primary colors. SUMMARY OF THE INVENTION It is an object of the present invention to provide a liquid crystal display device which solves the above-mentioned problems of the prior art, improves white luminance, and can control the color temperature independently of the color tone of the three primary colors.

[0021]

In order to achieve the above object, the present invention mainly employs the following two means.

First, each pixel is composed of four unit pixels, and three of the three unit pixels have three primary colors, for example, red, green,
A color filter for blue display is arranged, and the remaining one unit pixel is dedicated to white display with a transmittance of 100% without disposing a color filter.

In the case of this configuration, for example, the area of each unit pixel becomes 1/4 in even distribution, and the unit pixel (R, G, B) in which the color filter is arranged enters the color filter. Assuming that the light is 1, 1 × (1/4) × (2/3) = 1/6.

In the unit pixel dedicated to white display, three colors of red, green and blue are used.
Since there is almost no light absorption at each wavelength corresponding to the primary colors, the unit pixel dedicated to white display is 1 × (１ ／) = 1/4, and the luminance of one pixel is the total of these. /
It becomes 12.

This is 1.875 times that of the existing system 2/9, and the luminance can be improved by 87% or more.

A second solution is that a color filter for white display is arranged in the unit pixel dedicated to white display.

In this case, the brightness of the unit pixel portion (three unit pixels) in which the color filters of the three primary colors are arranged is the same as above: 1 × (1/4) × (2/3) = 1/6 The brightness of the display-only unit pixel is 1 × (1/4) × (2/3) = 1/6, assuming that the transmittance of the white color filter is ／, which is the same as the three primary colors. Is 1/6 + 1/6 = 1/3
Thus, the luminance can be improved by 50% or more as compared with 2/9 of the prior art.

Further, among these, the unit pixel portions corresponding to the three primary colors can be set independently of the setting of the white color temperature in order to improve the reproducibility of each primary color. That is, since the white unit pixel is used only for displaying white, the color tone of the color filter can be set independently of the reproducibility of the three primary colors. At this time, if the color tone of the white color filter is set such that the shorter wavelength side absorptance is higher than the longer wavelength side among the light absorptances in the wavelength region within the visible region, the white color will be in the red direction, that is, the color temperature will be lowered Can be set to

Conversely, if the short-wavelength side absorptance of the light absorptance in the wavelength region within the visible region is lower than the long-wavelength side, white is set in the blue direction, that is, the color temperature is increased. can do. As a result, it is possible to easily realize both control of the white color temperature and color reproducibility of the three primary colors.

Since the transmittance of light from the backlight does not become 100% by disposing a color filter for setting the above-mentioned color temperature also in the white unit pixel as in the latter case, one pixel Will be lower than the former case.

Based on the technical concept of each means described above, the present invention is characterized by having the following constitutions (1) to (19).

(1) A liquid crystal composition is sandwiched between a pair of substrates, one of the pair of substrates has color filters of different hues for color display, and the other has a switching element for pixel selection. In a liquid crystal display device, a pixel constituting one dot for performing the color display is constituted by four unit pixels, and corresponds to an area of three unit pixels on the other substrate among the four unit pixels. A color filter corresponding to the three primary colors is arranged on the one substrate, and a color filter corresponding to white is arranged in an area corresponding to another unit pixel.

(2) The light absorption coefficient of the color filter corresponding to white in (1) with respect to the wavelength in the visible wavelength region is made different between the long wavelength side and the short wavelength side in the visible region.

(3) In the color filter corresponding to the white color in (1), the light absorption coefficient on the long wavelength side in the visible wavelength region is made larger than the light absorption coefficient on the short wavelength side, and the color filter corresponding to the white color is used. The color temperature of white displayed by the unit pixels having the color filters is higher than the color temperature of white displayed by the three unit pixels having the three primary color filters.

(4) In the color filter corresponding to white in (1), the light absorption coefficient on the long wavelength side in the visible wavelength region is made smaller than the light absorption coefficient on the short wavelength side, and the color filter corresponding to white is used. The color temperature of white displayed by the unit pixels having the color filters is lower than the color temperature of white displayed by the three unit pixels having the three primary color filters.

(5) On one of the substrates on which the color filter is formed in (3) or (4), the light absorption coefficient for the wavelength in the visible wavelength region is different between the long wavelength side and the short wavelength side in the visible region. A transparent film was formed covering the entire surface of the color filter.

(6) In the transparent film in (5), the light absorption coefficient with respect to the wavelength in the visible wavelength range is different between the long wavelength side and the short wavelength side in the visible wavelength range.

(7) In the transparent film of (6), three unit pixels each having a color filter of the three primary colors, wherein the light absorption coefficient on the long wavelength side in the visible wavelength region is larger than the light absorption coefficient on the short wavelength side. The color temperature of white displayed by the unit pixels other than the above is higher than the color temperature of white displayed by the three unit pixels having the three primary color filters.

(8) In the transparent film of (6), three unit pixels each having a color filter of the three primary colors, wherein the light absorption coefficient on the long wavelength side in the visible wavelength region is smaller than the light absorption coefficient on the short wavelength side. The color temperature of white displayed by the unit pixels other than the above is lower than the color temperature of white displayed by the three unit pixels having the three primary color filters.

(9) Of the four unit pixels constituting each of the pixels in (1) to (8), the size of the three unit pixels forming the color filter corresponding to the three primary colors is set to the other one. Larger than the size of one unit pixel.

The generation of a video signal in the liquid crystal display device having the above configuration is performed as follows.

(10) A video signal line for supplying a video signal to the four unit pixels constituting the pixel in (1) to (9) is made independent for each of the unit pixels.

(11) Of the four unit pixels constituting the pixel in (1) to (11), a video signal supplied to a unit pixel excluding the unit pixel corresponding to the three primary colors corresponds to the three primary colors. In this case, the image data is generated by an operation based on the video signal supplied to the unit pixel.

(12) Of the four unit pixels constituting the pixel in (11), the gradation data of the video signal supplied to the unit pixels excluding the unit pixels corresponding to the three primary colors is input to the unit pixels. In addition to the normally black mode in which the gradation data becomes higher and the light transmittance of the unit pixel increases, the gradation data of the video signal supplied to the unit pixels excluding the unit pixels corresponding to the three primary colors is converted into the 3
The smallest value among the three gradation data of the video signal input to each unit pixel corresponding to the primary color was used.

(13) Among the four unit pixels constituting the pixel in (11), the gradation data of the video signal supplied to the unit pixels excluding the unit pixels corresponding to the three primary colors is input to the unit pixels. In addition to the normally white mode in which the gradation data increases and the light transmittance of the unit pixel decreases, the gradation data of the video signal supplied to the unit pixels excluding the unit pixels corresponding to the three primary colors is converted into the normal white mode. 3
The largest value among the three gradation data input to each unit pixel corresponding to the primary color was used.

(14) Among the four unit pixels constituting the pixel in (11) to (13), the gradation data of the video signal supplied to the unit pixels excluding the unit pixels corresponding to the three primary colors is The analog gradation data supplied to the unit pixels corresponding to the three primary colors is calculated by an analog circuit and calculated as analog gradation data.

(15) Among the four unit pixels constituting the pixel in (11) to (13), the gradation data of the video signal supplied to the unit pixels excluding the unit pixels corresponding to the three primary colors is The digital gradation data supplied to the unit pixels corresponding to the three primary colors is calculated by a digital circuit and calculated as digital gradation data.

(16) Calculation of gradation data of video signals supplied to the unit pixels excluding the unit pixels corresponding to the three primary colors out of the four unit pixels constituting the pixels in (11) to (13) Is performed by an arithmetic circuit built in a controller that controls the display of the liquid crystal display device.

(17) Calculation of the gradation data of the video signal supplied to the unit pixels excluding the unit pixels corresponding to the three primary colors out of the four unit pixels constituting the pixels in (11) to (13). Is performed by an arithmetic circuit built in the video signal drive circuit of the liquid crystal display device.

(18) Calculation of the gradation data of the video signal supplied to the unit pixels excluding the unit pixels corresponding to the three primary colors among the four unit pixels constituting the pixels in (11) to (13). Is performed by an arithmetic circuit formed integrally with the video signal drive circuit on the substrate on which the video signal lines are formed.

(19) Among the four unit pixels constituting the pixel in (11) to (13), the calculation of the gradation data supplied to the unit pixels excluding the unit pixels corresponding to the three primary colors is performed by a liquid crystal display. The operation is performed by an arithmetic circuit interposed between a controller for controlling display of the device and a video signal drive circuit.

With the above arrangements, the white luminance is improved,
An active matrix liquid crystal display device capable of controlling the color temperature independently of the three primary colors is obtained.

[0053]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to examples.

[First Embodiment] FIG. 1 schematically shows a unit pixel region constituting one pixel and a function of a reproduced color possessed by each unit pixel for explaining a first embodiment of the liquid crystal display device according to the present invention. (A) is a plan view of one pixel,
(B) is a plan view showing the arrangement of a plurality of pixels.

In this embodiment, as shown in FIG. 1A, pixels for reproducing only white are added in addition to red, green and blue, and four unit pixels of R, G, B and W are added. Constituted one pixel. By arranging a large number of these pixels on the display surface, an effective display area is formed as shown in FIG. Each unit pixel R, G,
B and W have the same area, each of which is 1/4 of one pixel.
As described in the section of the means for solving the problem, the white luminance can be improved as compared with the conventional pixel configuration.

FIG. 2 is a cross-sectional view taken along the line AA ′ of FIG. 1. 1A is a color filter substrate, which is one of a pair of substrates of a liquid crystal panel constituting a liquid crystal display device of a horizontal electric field type; BM denotes a black matrix which is a light shielding film, R denotes a red filter, G denotes a green filter, B denotes a blue filter, ORI denotes an alignment film, and LC denotes a liquid crystal layer.

In the first embodiment, a color filter corresponding to each color is arranged in the unit pixel of each color of R, G, and B, and no color filter is arranged in the white unit pixel W. Things. Note that a transparent alignment film ORI is formed to cover the R, G, and B regions and the W region.

According to this embodiment, since the light from the backlight is transmitted without being absorbed by the unit pixel of W,
White luminance in a horizontal electric field type liquid crystal display device can be greatly improved.

[Second Embodiment] FIG. 3 is a sectional view of a second embodiment of the present invention taken along the line AA 'of FIG. 1, and 1A shows a liquid crystal panel constituting a vertical electric field type liquid crystal display device. A color filter substrate, which is one of the pair of substrates, COM is a common electrode, and the same reference numerals as those in FIG. 2 correspond to the same functional portions.

In this embodiment, a color filter corresponding to each color is disposed in each of the R, G, and B unit pixels, and no color filter is disposed in a unit pixel corresponding to the white unit pixel W. In this embodiment, the common electrode C is further covered with a transparent conductor, for example, ITO, so as to cover the R, G, and B color filter regions and the unit pixel region of W.
An OM was formed, and an orientation film ORI was formed thereon.

According to this embodiment, it is possible to greatly improve white luminance in a vertical electric field type liquid crystal display device which requires a transparent common electrode on a color filter substrate.

The present embodiment can be similarly applied to a simple matrix type liquid crystal display device in which electrodes for selecting pixels are formed on a color filter substrate.

[Third Embodiment] FIG. 4 is a cross-sectional view of a third embodiment of the present invention, taken along the line AA 'in FIG. 1. OC is a transparent overcoat layer. Corresponds to the same functional part.

In this embodiment, a color filter corresponding to each of the R, G, and B unit pixels is provided, and a color filter corresponding to white is not provided to the unit pixel corresponding to W as in FIG. The configuration was adopted. Then, a transparent overcoat layer OC was formed to cover the area of each unit pixel.

According to the present embodiment, the color filter substrate 1A
White luminance in a horizontal electric field type liquid crystal display device having no electrode on the side can be greatly improved, and R,
The surface of each of the G and B color filters and the surface of the W unit pixel region can be flattened, and uneven gaps between a pair of substrates can be reduced.

[Fourth Embodiment] FIG. 5 is a sectional view of a fourth embodiment of the present invention taken along the line AA 'of FIG. 1, where OC indicates an overcoat layer and the same reference numerals as those in FIG. Corresponding to the part.

In this embodiment, as in the second embodiment, the present invention is applied to a liquid crystal display device having a transparent common electrode on the color filter substrate side. That is, R,
Color filters corresponding to the G and B unit pixels were arranged, and a transparent overcoat layer OC was formed to cover the R, G, and B regions and the unit pixels corresponding to white W. The common electrode COM is made of a transparent conductor, for example, ITO, and an orientation film ORI is further formed thereon.

According to this embodiment, the white luminance can be greatly improved, and the surfaces of the R, G, B color filter regions and the W unit pixel region can be flattened. Further, the gap unevenness between the pair of substrates can be reduced, and the surface of the color filter can be flattened more than in the third embodiment shown in FIG. 3 to reduce defects due to disconnection of the common electrode.

[Fifth Embodiment] In this embodiment, the light absorption coefficient of the overcoat layer OC in the visible wavelength region of the overcoat layer OC in the fourth and fifth embodiments is smaller than the light absorption coefficient of the short wavelength side. It is a big one. .

According to this embodiment, even when the color tone of each of the R, G, and B color filters is the same as that of the conventional example, the color temperature of white can be higher than that of the conventional example.

Sixth Embodiment In this embodiment, the light absorption coefficient of the overcoat layer OC in the visible wavelength region in the fourth and fifth embodiments is longer than the light absorption coefficient in the short wavelength side. It is a smaller one. .

According to this embodiment, even when the color tone of each of the R, G, and B color filters is the same as that of the conventional example, the color temperature of white can be lower than that of the conventional example.

[Seventh Embodiment] FIG. 6 is a sectional view of a seventh embodiment of the present invention taken along line AA 'of FIG.
A color filter corresponding to each of the unit pixels B and W is arranged. For the white color filter, a transparent material that absorbs less light from the backlight is used. According to the present embodiment, it is possible to improve the white luminance in the liquid crystal display device of the in-plane switching mode, and it is possible to improve the flatness of the inner surface of the color filter substrate 1A as compared with the first embodiment.

[Eighth Embodiment] FIG. 7 is a sectional view of an eighth embodiment of the present invention taken along line AA 'of FIG.
A color filter corresponding to each of B and W unit pixels is arranged, and a common electrode COM such as ITO is formed. For the white color filter, a transparent material that absorbs less light from the backlight is used.

According to the present embodiment, the flatness of the inner surface of the color filter substrate 1A can be improved as compared with the case of the second embodiment, and a transparent common electrode is required on the color filter substrate other than the horizontal electric field type. Of the common electrode in the liquid crystal display device to be performed can be reduced.

[Ninth Embodiment] FIG. 8 is a sectional view of a ninth embodiment of the present invention taken along the line AA 'in FIG.
A color filter corresponding to each of B and W unit pixels is formed, and a transparent overcoat layer OC is formed thereon.

According to this embodiment, the flatness of the inner surface of the color filter substrate in the in-plane switching mode liquid crystal display device having no electrode on the color filter substrate side can be improved. Further, the contamination of the liquid crystal layer from the color filter material is reduced by the overcoat layer OC, so that the reliability of the liquid crystal display device can be improved.

[Tenth Embodiment] FIG. 9 is a sectional view of a tenth embodiment of the present invention, taken along line AA 'of FIG. In this example, a color filter corresponding to each of the R, G, B, and W unit pixels was formed, and a transparent overcoat layer was formed so as to cover the R, G, B, and W color filters. Then, a transparent conductor such as IT
The common electrode COM is formed with O.

According to the present embodiment, it is possible to improve the brightness of a liquid crystal display device that requires a transparent common electrode or the like on a color filter substrate other than the horizontal electric field type, and it is possible to improve the flatness of the inner surface of the color filter substrate. Also, the common electrode C
It is possible to reduce the defective rate due to the disconnection of the OM. Further, the liquid crystal layer L is removed from the color filter material by the overcoat layer OC.
Since contamination to C is reduced, the reliability of the liquid crystal display device can be improved.

[Eleventh Embodiment] In this embodiment, the light absorption coefficient of the W color filter of the seventh embodiment to the tenth embodiment described with reference to FIGS. This is larger than the light absorption coefficient on the wavelength side.

According to this embodiment, R, which corresponds to the three primary colors,
Even when the color filter provided in each of the G and B unit pixels has the same color tone as the conventional example, the color temperature of the white W can be higher than in the conventional example.

[Twelfth Embodiment] In the twelfth embodiment, the light absorption coefficient on the long wavelength side in the visible wavelength region of the W color filter in the seventh to tenth embodiments described with reference to FIGS. It is smaller than the light absorption coefficient on the wavelength side.

According to this embodiment, R corresponding to the three primary colors,
Even when the color tones of the color filters provided in the G and B unit pixels are the same as in the conventional example, the color temperature of the white W can be lower than in the conventional example.

[Thirteenth Embodiment] FIG. 10 schematically shows a unit pixel area constituting one pixel and a function of a reproduced color possessed by each unit pixel for explaining a thirteenth embodiment of the liquid crystal display device according to the present invention. It is a top view. In this embodiment, the area of each of the R, G, and B unit pixels constituting one pixel is different from the area of the W unit pixel, so that the area of the W unit pixel is R,
It is smaller than the area of the G and B unit pixels.

In each of the embodiments described above, as shown in FIG. 1, since the regions of R, G, B, and W are equal, the difference between the white luminance and the luminance of the three primary colors is large. Therefore, in the present embodiment, the area of the unit pixel of W is smaller than that of each of the R, G, and B unit pixels.

According to the present embodiment, it is possible to achieve both the balance with the luminance of the R, G, and B unit pixels while realizing the effect of improving the luminance of W.

The sectional structure described with reference to FIGS. 2 to 9 can be similarly applied to the pixel structure of FIG.

FIG. 11 is a block diagram for explaining the schematic arrangement of the driving means of the liquid crystal display device according to the present invention.
Denotes a scanning signal line, 103 denotes a video signal line, 400 denotes a liquid crystal panel (also referred to as a liquid crystal display panel), 401 denotes a controller, 402 denotes a liquid crystal driving power supply circuit, 403 denotes a vertical scanning circuit, 404 denotes a video signal driving circuit, and 500 denotes a host. 1 shows a CPU of a computer. In the drawing, the reference potential is required in an active matrix type liquid crystal display device, and is not necessary when applied to a simple matrix type liquid crystal display device.

The display data and control signals are formed by the controller 401 based on the display data input to the liquid crystal display device. The liquid crystal display panel 400 has a
A large number of pixels are formed of R, G, and B unit pixels as described with reference to FIG. Controller 40
The display data output from 1 is applied to the video signal drive circuit 404 together with the control signal, and supplied to the switching element of each unit pixel via the video signal line 103. Further, the control signal is also applied to the vertical scanning circuit 403, and is applied to the scanning electrode of each pixel via the scanning signal line.

In such a pixel configuration, a configuration for supplying a signal for displaying the unit pixel W for white display among the pixels to the unit pixel of W is required.

FIG. 12 is a plan transmission diagram schematically illustrating the pixel configuration of one pixel of the TN or STN mode liquid crystal display device. On the substrate on which the color filter is formed, the common electrode COM is formed of a transparent conductive film, for example, ITO or a laminate of the transparent conductive film and a metal thin film, and is shared by the R, G, B, and W unit pixels. On the other hand, video signal lines RV, GV, BV, and WV are formed independently of the R, G, B, and W unit pixels on the opposing substrate.

The common electrode COM corresponds to the scanning signal line 102 in FIG. 11, and RV, GV, BV, and WV correspond to the video signal line 103.

If the scanning signal line is formed separately with the unit pixel of W and the unit pixels of R, G and B, the frequency of the scanning signal is doubled. At the same time, the frequency of the video signal is also doubled because it is synchronized with the frequency of the scanning signal. As a result, in order to display an image of the same resolution, it is necessary to double the frequency of both the scanning signal line and the video signal line, and the cost of each driver element is greatly increased.

In this configuration example, the scanning signal line is shared by the R, G, B, and W unit pixels in the unit pixel, and the video signal line is provided independently for each unit pixel, so that the scanning signal line and the scanning signal line are shared. The liquid crystal display device can be driven while the frequency of the video signal line remains the same as the conventional one, and a low-cost liquid crystal display device can be realized.

A block diagram of the driving relationship of this liquid crystal display device is as shown in FIG. 11, and the liquid crystal display panel includes:
As shown in FIG. 1B, the entire display area is
The pixel of (a) is formed.

FIG. 13 is a transparent plan view schematically showing an example of the configuration of a TFT type unit pixel. RV, GV, B
V and WV are video signal lines, SL is a scanning signal line, 15 is a semiconductor layer, 10 is a source electrode, 20 is a transparent conductor, for example, I
It is a pixel electrode made of TO.

On the substrate on which the color filters are formed,
The common electrode COM is entirely formed of a transparent conductive film, for example, ITO or a laminate of this and a metal thin film (not shown). A reference potential is input to the common electrode. on the other hand,
A video signal line R corresponding to the video signal line 103 in FIG. 11 is provided on the other substrate facing the substrate on which the color filter is formed.
V, GV, BV, and WV are provided independently for each unit pixel in the pixel. Also, the scanning signal line SL is
, R, G, B, and W in the pixel.
Are shared by the unit pixels.

In this configuration example, even in the so-called TFT type liquid crystal display device, the liquid crystal display element can be driven with the frequency of the scanning signal line and the video signal line being the same as in the prior art, as in the above-described embodiment. The liquid crystal display device of the present invention can be realized at low cost.

The block diagram of the driving circuit system in the liquid crystal display device of the horizontal electric field system is the same as that of FIG.

FIG. 14 is a plan transmission diagram schematically showing an example of the configuration of one pixel in the horizontal electric field system. RV, GV, BV,
WV is a video signal line, SL is a scanning signal line, 15 is a semiconductor layer, 20 is a pixel electrode, 31 is a reference electrode, and 31 is a reference signal line connected to the reference electrode. A reference potential is input to the reference signal line. On the other hand, video signal lines RV, GV, BV, and WV corresponding to the video signal line 103 in FIG. 11 are provided independently on each unit pixel in one pixel on the substrate facing the substrate on which the color filter is formed. . Also, the scanning signal line SL
Is shared by the R, G, B, and W unit pixels in the pixel, and corresponds to the scanning signal line 102 in FIG.

In this configuration example, even in the so-called horizontal electric field type liquid crystal display device, the liquid crystal display element can be driven with the frequencies of the scanning signal lines and the video signal lines being the same as in the prior art, as in the above embodiment. The liquid crystal display device of the present invention can be realized at low cost.

In the liquid crystal display device of the in-plane switching mode, the aperture ratio is reduced by the TN mode because of the presence of the comb electrodes in the pixels.
It is usually about half that of the FT liquid crystal display device, and the light use efficiency of the liquid crystal display device is usually about half. On the other hand, in the present configuration example, the light use efficiency is about twice that of the conventional example. Therefore, in the in-plane switching mode liquid crystal display device to which the present invention is applied, the light use efficiency is reduced by TN when the present invention is not applied. It can be made almost equivalent to the TFT type liquid crystal display device, and can eliminate the disadvantage of power consumption of the liquid crystal display device of the lateral electric field type with respect to the TN type TFT liquid crystal display device, and has a wide viewing angle and low power consumption. A compatible liquid crystal display device can be realized.

FIG. 15 is an explanatory diagram showing the relationship between the gradation-luminance characteristics of the liquid crystal display device according to the present invention and the gradation of display data input to a white unit pixel. Here, in a so-called normally black mode, in which the light transmittance of each unit pixel increases as the gradation input to the pixel increases, the gradation data input to the unit pixel corresponding to white corresponds to the three primary colors. Out of the three gradation data input to each unit pixel
The smallest value was set. How to set the display data to be displayed on the white W unit pixel is a decisive problem in display quality. That is, the colors reproduced by the R, G, and B gradation data are diversified. For this reason, when the white color displayed by the white W pixel loses the balance of the color reproduced by the R, G, and B gradation data, the display image is completely different from the original display data.

In the normally black mode, R,
Of the G and B gradation data, the gradation data corresponding to the smallest gradation is input to any of the R, G, and B unit pixels, that is, white for this gradation is displayed. .

Therefore, the gradation data to be input to the white W unit pixel is converted to the three-color input to each pixel corresponding to the three primary colors.
By setting the smallest value among the two pieces of gradation data, it is possible to improve the luminance while preventing the color balance from being shifted.

FIG. 16 is an explanatory diagram showing the relationship between the gradation-luminance characteristics of the liquid crystal display device according to the present invention and the display gradation inputted to the white unit pixel. In a so-called normally white mode, in which the grayscale data input to a unit pixel increases and the light transmittance of the unit pixel decreases, the grayscale data input to a pixel pixel corresponding to white is converted to the three primary colors. Of the three gradation data input to each corresponding unit pixel, the largest value was set.

In the present invention, how to set display data to be displayed on the white unit pixel W is a decisive problem in display quality. That is, the colors reproduced by the R, G, and B gradation data are diversified. For this reason, when the white color displayed by the white W unit pixel loses the balance of the color reproduced by the R, G, and B gradation data, the display image is completely different from the original gradation data. .

In the normally white mode, R,
Of the G and B display data, the data corresponding to the largest gradation is input to any of the R, G and B unit pixels, that is, white corresponding to this gradation is displayed.

Therefore, by making the gradation data inputted to the white W unit pixel the largest value among the three gradation data inputted to each unit pixel corresponding to the three primary colors,
It is possible to improve the luminance while preventing the color balance from shifting.

As for the generation of the display data, in a liquid crystal display device having an analog driver, the operation of the gradation data supplied to the white W unit pixel is calculated by an analog circuit and is derived as analog gradation data.

As a result, the A / D and D / A conversion processes are not required for calculating the white W gradation data, so that the above-described white W gradation data can be calculated with a low-cost circuit configuration, and high luminance can be obtained. Thus, a low-cost liquid crystal display device can be realized.

In a liquid crystal display device having a digital driver, the operation of gradation data supplied to a white W unit pixel is calculated by a digital circuit and is derived as a digital gradation.

This eliminates the need for the D / A and A / D conversion processes in calculating the grayscale data of white W, so that the grayscale data of white W can be calculated with a low-cost circuit configuration. A cost-effective liquid crystal display device can be realized.

FIG. 17 is a block diagram illustrating a first configuration example of a video signal system including a circuit for calculating gradation data to be supplied to a white unit pixel. In this configuration, a W gradation operation circuit 60 that calculates gradation data to be supplied to a white unit pixel is supplied to a controller 401 that inputs R, G, and B gradation data.
0 is built-in.

By providing the W gradation operation circuit 600 inside the controller 401, the number of outputs of the video signal drive circuit 404 is increased by 4/3 and the frequency of the signal transmitted to the video signal drive circuit 404 is increased by 4/3. The object of the present invention can be achieved without any change in other circuit configurations only by the configuration. Especially,
When a digital driver is used, only a memory for one unit pixel of each of R, G, and B and a comparison circuit are provided in the controller 401. Since a circuit for calculating tone data can be configured, white tone data can be generated at very low cost.

FIG. 18 is a block diagram for explaining a second configuration example of a video signal system provided with a circuit for calculating gradation data to be supplied to a white unit pixel. In this configuration, the video signal drive circuit 404 is provided with a W gradation calculation circuit 600 for calculating white W gradation data.

With this configuration, other circuits can be completely shared with the conventional example, so that the cost of parts can be reduced and the design can be simplified.

FIG. 19 is a block diagram for explaining a third configuration example of a video signal system provided with a circuit for calculating gradation data to be supplied to a white unit pixel. FIG. 20 is a block diagram illustrating a fourth configuration example of a video signal system including a calculation circuit for grayscale data to be supplied to a white unit pixel.

In the configuration shown in FIG. 19, a W gradation calculation circuit 600 for calculating white W gradation data is provided between the controller 401 and the video signal driving circuit 404.
0, a W gradation operation circuit 600 for calculating white W gradation data is provided between the controller 401 and the video signal driving circuit 404, and the W gradation operation circuit 600
Are independent of the signal paths of the R, G, B gradation data. As the controller 401 and the video signal drive circuit 404, cost reduction is realized by using general-purpose products commonly shared by other types. Therefore,
If these circuits are provided with dedicated circuits, they become custom products, and there is a problem in that the cost of parts is greatly increased. In this configuration example, the controller 401 and the video signal drive circuit 404 separately operate the W gradation operation circuit 60 for calculating the white W gradation data.
By providing 0, cost reduction can be realized.

Since the video signal drive circuit and the W gradation operation circuit are integrally formed on the substrate on which the video signal lines are formed, the video signal drive circuit 404 can be formed simultaneously with the TFT in the TFT manufacturing process. In addition, an external video signal driving circuit is not required, and cost reduction is realized. Furthermore, W
The gradation calculation circuit 600 can be formed integrally with the video signal driving circuit 404. Also, the video signal drive circuit is 4 /
Even if it is increased to 3, there is no increase in process and cost if it is formed integrally on the substrate. Therefore, in this case, the function of the present invention can be realized without increasing the cost.

It is needless to say that the above embodiments and configuration examples can be combined.

Further, the gradation data of white W is represented by R, G, B
May be calculated and determined according to a certain rule based on the grayscale data input to. In this case, the user can control the white color temperature by changing the rule.
In this case, it is desirable that the user can control the rule from outside the liquid crystal display element by a hardware or software mechanism.

In the above description, the description and illustration of the configuration of parts not directly related to the present invention are basically omitted.
That is, for example, the detailed configuration of the other substrate facing the spacer beads of the liquid crystal panel, the polarizing plate, the backlight, and the color filter substrate.

However, it goes without saying that the present invention has such a configuration in an actual configuration, and the present invention is actually configured to include the configuration having such a configuration.

FIG. 21 is an exploded perspective view showing each component of an example of the liquid crystal display device according to the present invention, which is modularized. SHD is a frame-shaped frame made of a metal plate (also referred to as a shield case or metal frame), WD is its display window, PNL is a liquid crystal panel, FMS is a surface light-shielding layer, SPS
Is a light diffusing plate, GLB is a light guide, RFS is a reflecting plate, BL is a fluorescent tube of a backlight, MCA is a lower case (backlight case), and each member is arranged vertically as shown in the figure. The module MDL is assembled by stacking.

The whole module MDL is fixed by claws and hooks provided on the frame SHD.

The backlight case MCA comprises a cold cathode fluorescent tube LP, a light diffusion plate SPS,
The cold cathode fluorescent tube LP has a shape for accommodating the light guide GLB and the reflection plate RFS, and is disposed on a side surface of the light guide GLB.
Is made uniform illumination light on the display surface by the light guide GLB, the reflection plate RFS, and the light diffusion plate SPS, and is emitted to the liquid crystal panel PNL side.

An inverter circuit board is connected to the cold cathode fluorescent tube LP, and serves as a power source for the cold cathode fluorescent tube LP.

FIG. 22 is a perspective view of a notebook personal computer as an example of an electronic apparatus on which the liquid crystal display device according to the present invention is mounted. The notebook computer (portable personal computer) includes a keyboard unit (main body unit) and a display unit connected to the keyboard unit by a hinge. The keyboard unit accommodates a keyboard and a signal generation function such as a host (host computer) and a CPU, and the display unit has a liquid crystal panel PNL, around which drive circuit boards PCB1 and PCB2, a control chip TCON and a CPU. A PCB 3 mounted with a connector CT or the like for connecting signals, an inverter power supply board serving as a backlight power supply, and the like are mounted.
This liquid crystal panel PNL has the alignment film described in each of the above embodiments.

Various circuit boards PCB1 and PCB on which the above-mentioned controller, video signal drive circuit, W gradation operation circuit and other functional circuits are mounted on the liquid crystal panel PNL.
2, the PCB 3, the inverter power supply board, and the backlight are integrated and mounted as a liquid crystal display module MDL.

[0131]

As described above, according to the present invention,
It is possible to provide a liquid crystal display device capable of improving white luminance and controlling the color temperature independently of the three primary colors.

[Brief description of the drawings]

FIG. 1 is a plan view schematically showing a unit pixel region constituting one pixel and a function of a reproduced color possessed by each unit pixel for explaining a first embodiment of a liquid crystal display device according to the present invention.

FIG. 2 is a sectional view taken along the line A-A 'of FIG.

FIG. 3 is a cross-sectional view of the second embodiment of the present invention, taken along line AA ′ of FIG.

FIG. 4 is a sectional view of a third embodiment of the present invention, taken along line AA ′ of FIG. 1;

FIG. 5 is a sectional view of the fourth embodiment of the present invention, taken along line AA ′ of FIG. 1;

FIG. 6 is a sectional view of a seventh embodiment of the present invention, taken along line AA ′ of FIG. 1;

FIG. 7 is a sectional view of the eighth embodiment of the present invention, taken along line AA ′ of FIG. 1;

FIG. 8 is a sectional view of the ninth embodiment of the present invention, taken along line AA ′ of FIG. 1;

FIG. 9 is a sectional view of the tenth embodiment of the present invention, taken along line AA ′ of FIG. 1;

FIG. 10 is a plan view schematically showing a unit pixel region constituting one pixel and a function of a reproduced color possessed by each unit pixel for explaining a thirteenth embodiment of the liquid crystal display device according to the present invention.

FIG. 11 is a block diagram illustrating a schematic configuration of a driving unit of the liquid crystal display device according to the present invention.

FIG. 12 is a plan transmission diagram schematically illustrating a pixel configuration of one pixel of a TN or STN mode liquid crystal display device.

FIG. 13 is a plan transmission diagram schematically illustrating an example of a configuration of a TFT-type unit pixel.

FIG. 14 is a plan transmission diagram schematically illustrating an example of a configuration of one pixel in a horizontal electric field method.

FIG. 15 is an explanatory diagram showing a relationship between a gradation-luminance characteristic of the liquid crystal display device according to the present invention and a gradation of display data input to a white unit pixel.

FIG. 16 is an explanatory diagram showing the relationship between the gradation-luminance characteristics of the liquid crystal display device according to the present invention and the display gradation inputted to the white unit pixel.

FIG. 17 is a block diagram illustrating a first configuration example of a video signal system including an arithmetic circuit for grayscale data supplied to a white unit pixel.

FIG. 18 is a block diagram illustrating a second configuration example of a video signal system including an arithmetic circuit for gradation data to be supplied to a white unit pixel.

FIG. 19 is a block diagram illustrating a third configuration example of a video signal system including a calculation circuit for grayscale data supplied to a white unit pixel.

FIG. 20 is a block diagram illustrating a fourth configuration example of a video signal system including an arithmetic circuit for grayscale data supplied to a white unit pixel.

FIG. 21 is an exploded perspective view showing each component of an example of the liquid crystal display device according to the present invention which is modularized.

FIG. 22 is a perspective view of a notebook personal computer as an example of an electronic device on which the liquid crystal display device according to the present invention is mounted.

FIG. 23 is a plan view schematically showing each unit pixel region forming one pixel of a conventional liquid crystal display device and a function of a reproduced color of each unit pixel.

FIG. 24 is a schematic block diagram illustrating a circuit for generating red (R), green (G), and blue (B) gradation data applied to each unit pixel in a conventional liquid crystal display device.

[Explanation of symbols]

 Reference Signs List 1 1 pixel 1R R unit pixel 1G G unit pixel 1B B unit pixel 1W W unit pixel 15 Semiconductor layer 20 Pixel electrode 31 Reference electrode 31 Reference signal line 102 connected to reference electrode, SL scanning signal line 103, RV, GV, BV , WV video signal line 400 liquid crystal display panel 401 controller 402 liquid crystal drive power supply circuit 403 vertical scanning circuit 404 video signal drive circuit 500 CPU 600 W gradation arithmetic circuit.

Claims (2)

[Claims] 1. A liquid crystal having a liquid crystal composition sandwiched between a pair of substrates, having a color filter of a different hue for color display on one of the pair of substrates, and a switching element for selecting a pixel on the other. In the display device, a pixel forming one dot for performing the color display is formed of four unit pixels, and the one corresponding to an area of three unit pixels on the other substrate among the four unit pixels. A color filter corresponding to three primary colors, and a color filter corresponding to white in an area corresponding to another unit pixel. 2. A liquid crystal having a liquid crystal composition sandwiched between a pair of substrates, having a color filter of a different hue for color display on one of the pair of substrates, and a switching element for selecting a pixel on the other. In the display device, a pixel forming one dot for performing the color display is formed of four unit pixels, and the one corresponding to an area of three unit pixels on the other substrate among the four unit pixels. A color filter corresponding to the three primary colors is disposed on the substrate, and a color filter corresponding to white is disposed in a region corresponding to another unit pixel. A liquid crystal display device wherein the light absorption coefficient is made different on the long wavelength side and the short wavelength side in the visible region.